CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRARY = w l ^ - f- cJ = o c\\ - //a ^^^ s vw CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA iRSITY OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LI ERSITY OF CALIFORNIA IfD LIBRARY OF THE UNIVERSITY OF CALIFORNIA 6 L! EfiSITY OF CALIFORNIA l/fb LIBRARY OF THE UNIVERSITY OF CALIFORNIA DICTIONARY OF CHEMISTRY, IN WHICH THE PRINCIPLES OF THE SCIENCE ARE INVESTIGATED ANEW, AND ITS APPLICATIONS TO THE PHENOMENA OF NATURE, MEDICINE, MINERALOGY, AGRICULTURE, AND MANUFACTURES, DETAILED. v .< By ANDREW URE, M. D. F. R. S. , i PROFESSOR OK THE ANDERSONIAN INSTITUTION, MEMBER OP THE GEOLOGICAL AND ASTRONOMICAL SOCIETY OF LONDON, &C. &C. &C. tttttrotmctorg CONTAINING INSTRUCTIONS FOR CONVERTING THE ALPHABETICAL ARRANGEMENT INTO A SYSTEMATIC ORDER OF STUDY. WI7SHSIT THIRD EDITION, \& WITH NUMEROUS ADDITIONS AND / ; LONDON: PRINTED FOR THOMAS TEGG, 73, CHEAPSIDE ; T. HURST AND CO. ST. PAUL'S CHURCHYARD; s. HIGHLEY, AND T. AND G. UNDERWOOD, FLEET-STREET ; SIMPKIN AND MARSHALL, STATIONERS^ COURT : ALSO R. GRIFFIN AND CO. GLASGOW ; AND J. GUMMING, DUBLIN. 1828. 4k LONDON t PRINTED BY THOMAS DAV1SON ? WHlTEFRIARS. TO (A / THE IlIGHT HONOURABLE I &s&<$ THE EARL OF GLASGOW, BARON ROSS OP HAWKHEAD, &C. &C. &C. LORD-LIEUTENANT OF AYRSHIRE. MY WHEN I inscribe this volume to your Lordship, it is neither to offer the incense of adulation, which your virtues do not need, and your understanding would disdain j nor to solicit the patronage of exalted rank to a work, which in this age and nation must seek support in scientific value alone. The present dedication is merely an act of gratitude, as pure on my part, as your Lordship's condescension and kindness to me have been generous and unvarying. At my outset in life, your Lordship's distinguished favour cherished those studious pursuits, which have since formed my chief pleasure and business ; and to your Lordship's hospitality I owe the elegant retirement, in which many of the following pages were written. Happy would it have been for their readers, could I have transfused into them a portion of that grace of diction, and elevation of sentiment, which I have so often been permitted to admire in your Lordship's family. I have the honour to be, My LORD, Your Lordship's most obedient GLASGOW, November 7 , 1820. And very faithful Servant, ANDREW URE. 17 5 ADVERTISEMENT TO THE THIRD EDITION. THE very indulgent reception and rapid sale of the two preceding editions of this Dictionary merit my deepest gratitude. This I have now endeavoured to evince by the thorough revision bestowed in preparing the present one for the press. Whatever obsolete or useless details remained in it, I have been sedulous to expunge, and replace by matter equally interesting and new. Hence there seems to be no good reason for retaining the name of Nicholson in the title-page, as the portion of the work which can be truly traced to his pen has become nearly evanescent. On almost all occasions I have directly drawn the statement of facts, and the theoretic views, from the fountain-head of physical truth, the original memoirs of the great chemists who render our own times the golden age of corpuscular science. The delight with which the sagacity of genius there displayed ever inspires me, may have sometimes prompted terms of admiration beyond the comprehension, and sympathy, of the plodding pioneer of chemistry. The praise is however " of true desert," and flows from no motives of adulation. A few happy rhymes or musical periods, though conveying sentiments both trite and trivial, will enamour the hearts and kindle the fancies of the million ; while the optical revela- tions of Newton, and the electro-chemical magic of Davy, are either ne- glected altogether, or scanned with frigid tranquillity. As those alone can mount the steeps of science who are animated with the ardent love of truth, so none can rightly appreciate their discoveries and conquests unless in- spired with a kindred spirit. It must, however, be confessed that the listlessness with which chemical systems are frequently perused, is not entirely the fault of the reader. Too many of these books are dry compilations of names, qualities, and numbers, iii methodical complexity, containing no intelligible exemplar of VI ADVERTISEMENT. chemical inquiry j nay, hardly a trace of the genius of discovery, or of the toilsome career which it has run. The unhoped for, and in too many respects unmerited, success of this Dictionary may possibly be attributed to the models of inventive research, which I was careful to transfer into its pages from the master-memoirs of the modern school. He who can contemplate these without emotion need never hope to emulate the achieve- ments or renown of their authors. The same plan has been pursued with regard to the new additions just made to this work ; as the reader will perceive on consulting the articles Fluoric acid; Ferrocyanic acid, with the Ferroprussiates ; Sulp/w-naph- thalic acid ; Sulphovinic ; Titanic, &c. : as also Boron ; Brome, with its compounds ; Cyanogen ; Hydrogen ; Indigo ; Light ; Meteorite ; Mor- phia; Nickel; Nitrogen; Oil gas; Oil of Wine ; Phosphuretted Hydro- gen ; Silicium ; Sulphurets ; Titanium, and many others. The two tables now introduced under EQUIVALENTS (CHEMICAL) will furnish valuable aids to the chemical student, affording him a key to the writings of Berzelius, which he might otherwise find unintelligible, as also to those of our chemists who adopt hydrogen for their atomic unity. My own predilections, indeed, are in favour of this scale ; but the oxygen one was so interwoven with the former editions of the Dictionary that I did not deem it expedient to eradicate what many of our most eminent philosophers, with Dr. Wollaston at their head, still prefer. By this means too the three prevailing atomic systems are laid before my readers. Some may imagine that I might have imitated other modern compilers, and have saved myself the labour of canvassing the weights of many of the atoms, by adopting the numbers given by Dr. Thomson in his recent pub- lication on the First Principles of Chemistry. I have examined this work with attention. It displays the characteristic industry and ingenuity of the author. But the never failing concurrence, even to the second or third decimal place, of his experimental numbers, with the multiple numbers of hydrogen a general fact which he seeks to establish appears to me a precision in practice far beyond the present reach of human hands. Dr. Prout's proposition of the atomic weights of chemical bodies, being all multiples of that of hydrogen, by a whole number, is a very probable idea j but we must beware of suffering our hypothetical notions to influence our appreciation of experimental results. I humbly apprehend that Dr. Thom- son, under the power of this illusion, has vitiated many of the most important subjects of our science; of which, unexceptionable and very striking evidence will be found under the articles ACID (FLUORIC) and PHOSPHURETTED HYDROGEN. Many of the numbers adopted by him ADVERTISEMENT. Vli coincide with those Reducible from the prior researches of British and foreign chemists. A few he has no doubt rectified in the course of his numerous trials of saline decompositions. I have admitted some of these into my general table of SALTS. The more extensive the range which we take among the original me- moirs of the eminent chemists of this and the immediately preceding age, the more defects we shall observe in our modern compilations. The best of these, indeed, can be regarded merely as brief summaries ; and the most curiously methodical as a collection of facts and reasonings broken down into fragments, fitted to a tesselated system, certainly not very like the system of nature. Hence, the former collections, though valuable in many respects, will never quench the ardent thirst of knowledge ; while the latter can hardly fail to perplex the common mind. Moreover, in many fields of chemical literature the English language is entirely barren. Is it to be believed, that in a country where the iron trade, if not its staple, is the basis of all its manufactures, there should not exist any separate treatise on iron, its ores, and steel ? The Germans possess about fifteen respectable works on these subjects. There is no English book on metallurgy, a busi- ness in an immense British capital is engaged. The experienced chemical manufacturer laughs, as he well may, at most of our essayists on the che- mical arts, the processes prescribed by whom, if pursued in practice, would soon involve their dupes in bankruptcy. Let those who think this censure too severe seek for answers in our books to the following questions on the primary chemical art, the forma- tion of sulphuric acid : What is the just quantity of sulphur to be burned daily, relative to the capacity of the leaden chamber ? Whether is the continuous or intermitting combustion most pro- ductive ? What is the proper temperature to be maintained in the chamber ? What are the operation and effect of introducing steam ? At what stage of the combustion, and to what extent, ought it to be admitted ? To what degree of density is it advantageous to carry the acid in the chamber ? Whether should the sulphur and nitre be mixed prior to combustion, or the sulphur be set on fire by itself, the nitre being placed in a pot over its flame ? Similar questions, of equal importance, may be put on many 'other che- mical arts, of which satisfactory explanations will be vainly sought for in Vlll ADVERTISEMENT. books. These, indeed, present but a slight examination of the principles of the processes, if any at all, and seldom or never calculate proportions or results. As far as relates to the arts, they are, it must be confessed, here- ditary transcriptions. To supply such desiderata in our chemical literature is an undertaking peculiarly arduous, of which the entire accomplishment cannot be expected from a single mind. Yet diligence may do much ; and will not be dis- appointed of its reward, though much should remain undone. Under this conviction, I have for many years been collecting materials for such a body of chemical knowledge, and having matured my plans, I am now preparing it for the press. Though comprehensive, it will not be cumbersome ; for it will be so subdivided as to furnish students with a copious elementary text-book ; manufacturers with explicit rules for conducting their respec- tive arts ; practical chemists with an ample tableau raisonne of the methods and resources of analytical science ; and, finally, general readers with de- velopments of natural phenomena, presenting simplified modes of exa- mining the productions of nature, and of readily ascertaining the con- stituents of earthy minerals, mineral waters, ores, and soils. Glasgow, October 30, 1827- INTRODUCTION. IN this Introduction I shall present a GENERAL VIEW of the objects of chemistry, along with a scheme for converting the alphabetical arrangement adopted in this volume into a systematic order of study. THE forms of matter are numberless, and subject to incessant change. Amid all this variety, which perplexes the common mind, the eye of science discerns a few unchangeable primary bodies, by whose reciprocal actions and combinations this marvellous diversity and rotation of existence are produced and maintained. These bodies, having resisted every attempt to resolve them into simpler forms of matter, are called undecompounded, and must be regarded in the present state of our knowledge as experimental elements. It is possible that the elements of nature are very dissimilar ; it is probable that they are altogether unknown; and that they are so recondite, as for ever to elude the sagacity of human research. The primary substances which can be subjected to measurement and weight are fifty.two in number. To these, some chemists add the imponderable elements, light, heat, elec- tricity, and magnetism. But their separate identity is not clearly ascertained. Of the fifty-two ponderable principles, four, possibly five, require a distinct collocation from the marked peculiarity of their powers and properties. These are named Chlorine. Oxygen, Iodine, Fluorine, and Bromine. These bodies display a pre-eminent activity of combination, an intense affinity for most of the other forty-seven bodies, which they corrode, penetrate, and dissolve ; or, by uniting with them, so impair their cohesive force, that they become friable, brittle, or soluble in water, however dense, refractory, and insoluble they previously were. Such changes, for example, are operated on platinum, gold, silver, and iron, by the agency of chlorine, oxygen, or iodine. But the characteristic feature of these archeal elements is this, that when a compound consisting of one of them, and one of the other forty-seven more passive elements, is exposed to voltaic electrization, the former is uniformly evolved at the positive or vitreo-electric pole, while the latter appears at the negative or resino-electric pole. The singular strength of their attractions for the other simple forms of matter is also manifested by the production of heat and light, or the phenomenon of combustion, at the instant of their mutual combination. But this phenomenon is not characteristic ; for it is neither peculiar nor necessary to their action, and, therefore, cannot be made the basis of a logical arrangement. Combustion is vividly displayed in cases where none of these primary dissolvents is concerned. Thus certain metals combine with others with such vehemence as to elicit light and heat ; and many of them, by their union with sulphur, even in vacuo, exhibit intense combustion. Potassium bums distinctly in cyanogen (car- buretted azote), and splendidly in sulphuretted hydrogen. For other examples to the same purpose, see COMBUSTIBLE and COMBUSTION. b x INTRODUCTION. And again, the phenomenon of flame does not necessarily accompany any of the actions of oxygen, chlorine, and iodine. Its production may be regulated at the pleasure of the chemist, and occurs merely when the mutual combination is rapidly effected. Thus chlorine or oxygen will unite with hydrogen, either silently and darkly, or with fiery explosion, as the operator shall direct. Since, therefore, the quality of exciting or sustaining combustion is not peculiar to these electro-positive elements ; since it is not indispensable to their action on other substances, but adventitious and occasional, we perceive the inaccuracy of that classification which sets these three or four bodies apart under the denomination of supporters of combtistion ; as if combustion could not be supported without them, and as if the support of combustion was their indefeisible attribute, the essential concomitant of their action. On the contrary, every change which they can produce, by their union with other elementary matter, may be effected without the phenomenon of combustion. See section 5th of article COM- BUSTION. The other forty-seven elementary bodies have, with the exception of azote (the solitary incombustible), been grouped under the generic name of combustibles. But in reality combustion is independent of the agency of all these bodies, and therefore combustion may be produced without any combustible. Can this absurdity form a basis of chemical classi- fication ? The decomposition of euchlorine, as well as of the chloride and iodide of azote, is accompanied with a tremendous energy of heat and light ; yet no combustible is present. The same examples are fatal to the theoretical part of Black's celebrated doctrine of latent heat. His facts are, however, invaluable, and not to be controverted, though the hypo- thetical thread used to connect them be finally severed. To the term combustibk is naturally attached the idea of the body so named affording the heat and light. Of this position, it has been often remarked, that we have no evidence whatever. We know, on the other hand, that oxygen, the incombustible, could yield, from its latent stores, in Black's language, both the light and heat displayed in combustion ; for mere mechanical condensation of that gas, in a syringe, causes their disengagement. A similar condensation of the combustible hydrogen occasions, I believe, the evolution of no light. From all these facts it is plain, that the above distinction is unphilosophical, and must be abandoned. In truth, every insulated or simple body has such an appetency to combine with, or is solicited with such attractive energy by, other forms of matter, whether the actuating forces be electo-attractive or electrical, that the motion of the particles con- stituting the change, if sufficiently rapid, may always produce the phenomenon of com- bustion. Of the forty-seven electro-negative elements, forty-one are metallic, and six non-metallic. The latter group may be arranged into three pairs : Irf, The gaseous bodies, HYDROGEN and AZOTE ; 2d, The fixed and infusible solids, CARBON and BORON. 3<7, The fusible and volatile solids, SULPHUR and PHOSPHORUS. The forty-one metallic bodies are distinguishable by their habitudes with oxygen, into two great divisions, the BASIFIABLE and ACIUIFIABLE metals. The former are thirty- four in number, the latter seven. Of the thirty-four metals, which yield by their union with oxygen salifiable bases, three are convertible into alkalis, nine into earths, and twenty-two into ordinary metallic oxides. Some of the latter, however, by a maximum dose of oxygen, seem to graduate into the acidifiable group, or at least cease to form salifiable bases. We shall now delineate a general chart of Chemistry, enumerating its various leading objects in a somewhat tabular form, and pointing out their most important relations, so that the readers of this Dictionary may have it in their power to study its contents in a systematic order. INTRODUCTION. xi CHEMISTRY is the science which treats of the specific differences in the nature of bodies, and the per- manent changes of constitution to which their mutual actions give rise. This diversity in the nature of bodies is derived either from the AGGREGATION or COM- POSITION of their integrant particles. The state of aggregation seems to depend on die relation between the cohesive attraction of these integrant particles, and the antagonizing force of heat Hence, the three general forms of solid, liquid, and gaseous, under one or other of which every species of material being may be classed. For instruction on these general forms of matter, the student ought to read, 1st, The early part of the article ATTRACTION; 2d, CRYSTALLIZATION; 3d, That part of CALORIC entitled, ' Of the change of state produced in bodies by caloric, independent of change of composition." He may then peruse the introductory part of the article GAS, and BALANCE, and LABORATORY. He will now be sufficiently prepared for the study of the rest of the article CALORIC, as well as that of its correlative subjects, TEMPERATURE, THERMOMETER, EVAPORATION, CONGELATION, CRYOPHORUS, DEW, and CLI- MATE. The order now prescribed will be found convenient In the articles CALORIC, there are a few discussions which the beginner may perhaps find somewhat difficult. These he may pass over at the first reading, and resume their consideration in the sequel. After Caloric he may peruse LIGHT, and the first three sections of ELECTRICITY. The article COMBUSTION will be most advantageously examined, after he has become acquainted with some of the diversities of COMPOSITION ; viz. with the four electro-positive dissolvents, oxygen, chlorine, bromine and iodine ; and the six non-metallic electro-negative elements, hydrogen, azote, carbon, boron, sulphur, and phosphorus. Let him begin with oxygen, and then peruse, for the sake of connexion, hydrogen and -water. Should he wish to know how the specific gravity of gaseous matter is ascertained, he may consult the fourth section of the article GAS. The next subject to which he should direct his attention is CHLORINE ; on which he will meet with ample details in the present Work. This article will bear a second perusal. It describes a series of the most splendid efforts ever made by the sagacity of man, to unfold the chemical mysteries of nature. In connexion with it he may read the articles CHLOROUS and CHLORIC OXIDES, or the protoxide and deutoxide of Chlorine. Let him next study the copious article Iodine from beginning to end. Carbon, boron, sulphur, phosphorus, and azote, must now come under review. Related closely with the first, he will study the carbonous oxide, carburetted and subcarburetted hydrogen. What is known of the element boron will be speedily learned ; and he may then enter on the examination of sulphur, sulphuretted hydrogen, and carburet of sulphur. Phosphorus and pliosphurctted hydrogen, with nitrogen or azote, and its oxides and chlorid.es, will form the conclusion of the first division of chemical study, which relates to the elements of most general interest and activity. The general articles Combustible, Combustion, and Safe-Lamp may now be read with advantage ; as well as the remainder of the article Attraction, which treats of affinity. Since in the present work the alkaline and earthy salts are annexed to their respective acids, it will be proper, before commencing the study of the latter, to become acquainted with the alkaline and earthy bases. The order of reading may therefore be the following : first, The general article alkali, then potash and potassium, soda and sodium, lithia and ammonia. Next, the general article earth; afterwards calcium and lime, barium and barytes, strontia, magnesia, alumina, silica, glucina, zirconia, and yttria. Let him now peruse the general articles acid and salt; and then the non-metallic oxygen acids, with their subjoined salts, in the following order: sulphuric, sulphurous; hyposulphurous, and hyposulphuric ; phospJwric, phosphorous, and hypophosphorotis ; xii INTRODUCTION. carbonic and chlorocarbonous ; boracic ; and lastly, the nitric and nitrous. The others may be studied conveniently with the hydrogen group. The order of perusing them may be, the muriatic (hydrochloric of M. Gay Lussac), chloric, and perchloric ; the hydriodic, iodic, and cl iriodic ; \h& fluoric, fluoboric, and fluosilicic ; the prussic (hydrocyanic* of M. Gay Lus^ac), ferroprussic, chloroprussic, and sulphur oprussic. The hydrosulphitrous and hydrotelhirous are discussed in this Dictionary, under the names of sulphitretted Jiydrogen, and telluretted hydrogen. These compound bodies possess acid powers, as well perhaps as arsenuretted hydrogen. It would be advisable to peruse the article cyanogen either before or immediately after prussic acid. As to the vegetable and animal acids, they may be read either in their alphabetical order, or in any other which the student or his teacher shall think fit. The metallic acids fall naturally under metallic chemistry ; on the study of which I have nothing to add to the remarks contained in the general article METAL. Along with each metal in its alphabetical place, its native state, or ores, may be studied. See ORES. The chemistry of organized matter may be methodically examined by perusing, first of all, the article vegetable kingdom, with the various products of vegetation there enumerated ; and then the article animal kingdom, with the subordinate animal products and adipocere. The article analysis may be now consulted ; then mineral WATERS ; equivalents (che- mical), and analysis of ores. The mineralogical department should be commenced with the general articles mineralogy and crystallography ; after which the different species and varieties may be examined under their respective titles. The enumeration of the genera of M. Mobs, given in the first article, will guide the student to a considerable extent in their methodical consideration. Belonging to mineralogy, are the subjects blowpipe, geology, with its subordinate rocks, ores, and meteorite. The medical student may read with advantage the articles acid (arsenioiis), antimony, bile, blood, calculus (urinary), the sequel of copper, digestion, gall-stones, galvanism, in- testinal concretion, lead, mercury, poisons, respiration, urine, - ' P^^mM&i C (i EMU i' A.I, A 1\K\ U ATI PLA ;*. v ABS IABRAZITE, ZEAGONITE, or GTS- MONDINE. A mineral which occurs in semi-globular masses, and in octohedral crys- tals with a square base. Colour grayish-white, sometimes with a tinge of blue. Yields to the nail, but occasionally hard enough to scratch glass. Brittle. Fracture conchoidal. Trans- lucent or transparent. Constituents: silica 41.4; lime 48.6; alumina 2.5; magnesia 1.5 ; oxide of iron 2.5. Reduced by acids to a jelly, without effervescence. Loses its lustre, and becomes friable before the blowpipe. It is found in the cavities of volcanic rocks, with calcareous spar, at Capo di Bove near Rome. Phillips' Mineralogy. ABSORBENT. An epithet introduced into chemistry by the physicians, to designate such earthy substances as seemed to check diarrhoea, by the mere absorption of the re- dundant liquids. In this sense it is obsolete and unfounded. The faculty of withdrawing moisture from the air is not confined to sub- stances which unite with water in every pro- portion, as the strong acids, dry alkalis, alka- line earths, and deliquescent salts, but is pos- sessed by insoluble and apparently inert bodies, in various degrees of force. Hence the term Absorbent merits a place in chemical nomen- clature. The substance whose absorbent power is to be examined, after thorough desiccation before a fire, is immediately transferred into a phial, furnished with a well ground stopper. When it is cooled, a portion of it is put into a large wide-mouthed bottle, where it is close- ly confined for some time. A delicate hygro- meter being then introduced, indicates on its scale the dryness produced in the enclosed air, which should have been previously brought to the point of extreme humidity, by suspending ABS a moistened rag within the bottle. The fol- lowing table exhibits the results of experi- ments made by Professor Leslie : Alumina causes a dryness of 84 degrees. Carbonate of magnesia, . 75 Carbonate of lime, ' "' \ k 70 Silica, . . v 1 . 40 Carbonate of barytes, . 32 Carbonate of strontites, . 23 Pipeclay, ... 85 Greenstone, or trap hi powder, 80 Shelly sea sand, . . 70 Clay indurated by torrefaction, 35 Clay strongly ignited, . 8 Greenstone ignited, . 23 Quartz do. . . 19 Decomposed greenstone, 86 Greenstone resolved into soil, 92 Garden mould, . . 95 The more a soil is comminuted by labour and vegetation, the greater is its absorbent power. This ingenious philosopher infers, that the fertility of soils depends chiefly on their dis- position to imbibe moisture; and illustrates this idea by recent and by disintegrated lava. May not the finely divided state most pene- trable by the delicate fibres of plants derive its superior power of acting on atmospherical vapour from the augmentation of its surface, or the multiplication of the points of contact ? In similar circumstances 100 gr. of the following organic substances absorb the fol- lowing quantities of moisture : Ivory 7 gT- boxwood 14, down 16, wool 18, beech 28. Charcoal, and other porous solids of a fibrous texture, have the faculty of absorbing gases in a remarkable degree ; for an account of M. de Saussure's excellent experiments on ACI ACI which subject, see the article Gas in this Dic- tionary. Leslie on Heat and Moisture. ABSORPTION. The passage of a gas, or vapour, into a liquid or solid substance ; or of a liquid into the pores of a solid. ACANTICONE. See PISTACITE. ACERATES. The acer campestre, or common maple, yields a milky sweetish sap, containing a salt with basis of lime, possessed, according to Scherer, of peculiar properties. It is white, semitransparent, not altered by the air, and soluble in nearly 100 parts of cold, or 50 of boiling water. ACERIC ACID. See ACID (AcERic). ACESCENT. Substances which become sour spontaneously, as vegetable and animal juices, or infusions. The suddenness with which this change is effected during a thunder storm, even in corked bottles, has not been accounted for. In morbid states of the sto- mach, also, it proceeds with astonishing ra- pidity. It is counteracted by bitters, antacids, and purgatives. ACETATES. Salts formed by the com- bination of acetic acid with alkalis, earths, and metallic oxides. See ACID (ACETIC). ACETIC ACID. See ACID (ACETIC). ACETOJMETER. An instrument for estimating the strength of vinegars. It is described under ACID (AcETic). ACETOUS. Of or belonging to vinegar. See ACID (ACETIC). ACHMIT. A mineral first distinguished by Bergmeister Strom. It has a brownish black or reddish brown colour, is spotted, grayish-green in the fracture, externafiy of a glassy lustre, and in the transverse fracture glimmering. Translucent in small fragments. It has four cleavages, two of which are parallel to the sides of an oblique four-sided prism, and the other two, less obvious, are parallel to the truncations of the acute lateral edges. The fracture is small grained. Specific gra- vity 5.24. Hardness such as to scratch glass. It is likewise crystallized hi oblique four-sided prisms, with truncated lateral edges, and very sharp four-sided terminal faces, the edges of which correspond with the lateral edges of the oblique prism. The sides are channelled in the direction of their length. According to Berzelius this mineral contains silica 55.25, peroxide of iron 31.25, protoxide of manga- nese 1.08, lime 0-72, soda 10.40, oxide of titanium a trace. He considers it as a bisili- cate of soda, combined with a bisilicate of iron. ACHROMATIC. Telescopes formed of a combination of lenses, which in a great measure correct the optical aberration arising from the various colours of light, are called achromatic telescopes. ACIDS. The most important class of chemical compounds. In the generalization of facts presented by Lavoisier and the asso- ciated French chemists, it was the leading doctrine that acids resulted from the union of a peculiar combustible base called the radical, with a common principle technically called oxygen, or the acidifier. This general posi- tion was founded chiefly on the phenomena exhibited in the formation and decomposition of sulphuric, carbonic, phosphoric, and nitric acids ; and was extended, by a plausible ana- logy to other acids whose radicals were un- known. " I have already shown," says Lavoisier, " that phosphorus is changed by combustion into an extremely light, white, flaky matter. Its properties are likewise entirely altered by this transformation ; from being insoluble in water, it becomes not only soluble, but so greedy of moisture as to attract the humidity of the air with astonishing rapidity. By this means it is converted into a liquid, consider- ably more dense, and of more specific gravity than water. In the state of phosphorus before combustion, it had scarcely any sensible taste ; by its union with oxygen, it acquires an ex- tremely sharp and sour taste ; in a word, from one of the class of combustible bodies, it is changed into an incombustible substance, and becomes one of those bodies called acids. " This property of a combustible substance, to be converted into an acid by the addition of oxygen, we shall presently find belongs to a great number of bodies. Wherefore strict logic requires that we should adopt a com- mon term for indicating all these operations which produce analogous results. This is the true way to simplify the study of science, as it would be quite impossible to bear all its spe- cific details in the memory if they were not classically arranged. For this reason we shall distinguish the conversion of phosphorus into an acid by its union with oxygen, and in ge- neral every combination of oxygen with a com- bustible substance, by the term oxygenation ; from this I shall adopt the verb to oxygenate ; and of consequence shall say, that in oxyge- nating phosphorus, we convert it into an acid. " Sulphur also, in burning, absorbs oxygen gas ; the resulting acid is considerably heavier than the sulphur burnt; its weight is equal to the sum of the weights of the sulphur which has been burnt, and of the oxygen ab- sorbed ; and, lastly, this acid is weighty, in- combustible, and miscible with water in all proportions. " I might multiply these experiments, and show, by a numerous succession of facts, that all acids are formed by the combustion of certain substances ; but I am prevented from doing so in this place by the plan which I have laid down, of proceeding only from facts already ascertained to such as are unknown, and of drawing my examples only from cir- cumstances already explained. In the mean time, however, the examples above cited may suffice for giving a clear and accurate con- ception of the manner in which acids are ACI 6 ACI formed. By these it may be clearly seen that oxygen is an element common to them all, and which constitutes or produces their aci- dity ; and that they differ from each other according to the several natures of the oxy- genated or acidified substances. We must, therefore, in every acid carefully distinguish between the acidifiable base, which M. de Morveau calls the radical, and " the acidifying principle or oxygen." Elements, p. 115. " Although we have not yet been able either to compose or to decompound this acid of sea salt, we cannot have the smallest doubt that it, like all other acids, is composed by the union of oxygen with an acidifiable base. We have, therefore, called this unknown sub- stance the muriatic base, or muriatic radical." P. 122. 5th Edition. Berthollet's sound discrimination led him to maintain that Lavoisier had given too much latitude to the idea of oxygen being the uni- versal acidifying principle. " In fact,'' says he, "it is carrying the limits of analogy too far to infer, that all acidity, even that of the muriatic, fluoric, and boracid acids, arises from oxygen, because it gives acidity to a great number of substances. Sulphuretted hydrogen, which really possesses the proper- ties of an acid, proves directly that acidity is not in all cases owing to oxygen. There is no better foundation for concluding that hydrogen is the principle of alkalinity not only in the alkalis, properly so called, but also in magnesia, lime, strontian^nd barytes, because ammonia appears to owe its alkalinity to hydrogen. " These considerations prove that oxygen may be regarded as the most usual principle of acidity, but that this species of affinity for the alkalis may belong to substances which do not contain oxygen; that we must not, therefore, always infer, from the acidity of a substance, that it contains oxygen, although this may be an inducement to suspect its ex- istence in it: still less should we conclude, because a substance contains oxygen, that it must have acid properties; on the contrary, the acidity of an oxygenated substance shows that the oxygen has only experienced an in- complete saturation in it, since its properties remain predominant." Amid the just views which pervade the early part of this quotation from Berthollet, it is curious to remark the solecism with which it terminates. For after maintaining that acidity may exist independent of oxygen, and that the presence of oxygen does not ne- cessarily constitute acidity, he concludes by considering acidity as the attribute of unsatu- rated oxygen. This unwarrantable generalization of the French chemists concerning oxygen, which had succeeded StahPs equally unwarrantable generalization of a common principle of com- bustibility in all combustible bodies, was first experimentally combated by Sir H. Davy, in a series of admirable dissertations published in the Philosophical Transactions. His first train of experiments was instituted with the view of operating by voltaic electricity on muriatic and other acids freed from water. Substances which are now known by the names of chlorides of phosphorus and tin, but which he then supposed to contain dry muriatic acid, led him to imagine that intimately combined water was the real acidifying principle, since acid properties were immediately developed in the above substances by the addition of that fluid, though previously they exhibited no acid powers. In July 1810, however, he advanced those celebrated views concerning acidification, which, in the opinion of the best judges, dis- play an unrivalled power of scientific research. The conclusions to which these led him were incompatible with the general hypothesis of Lavoisier. He demonstrated that oxymuri- atic acid is, as far as our knowledge extends, a simple substance, which may be classed in the same order of natural bodies as oxygen gas, being determined like oxygen to the positive surface in voltaic combinations, and like oxygen combining with inflammable sub- stances, producing heat and light. The com- binations of oxymuriatic acid with inflam- mable bodies were shown to be analogous to oxides and acids in their properties and powers of combination, but to differ from them in being for the most part decomposable by water : and finally, that oxymuriatic acid has a stronger attraction for most inflammable bodies than oxygen. His preceding decom- position of the alkalis and earths having evinced the absurdity of that nomenclature which gives to the general and essential con- stituent of alkaline nature, the term oxygen or acidifier ; his new discovery of the simplicity of oxymuriatic acid showed the theoretical sys- tem of chemical language to be equally vicious in another respect. Hence this philosopher most judiciously discarded the appellation oxymuriatic acid, and introduced in its place the name chlorine, which merely indicates an obvious and permanent character of the sub- stance, its greenish-yellow colour. The more recent investigations of chemists on fluoric, hydriodic, and hydrocyanic acids, have brought powerful analogies in support of the chloridic theory, by showing that hydrogen alone can convert certain undecompounded bases into acids well characterized, without the aid of oxygen. Dr. Murray indeed endeavoured to revive and new-model the early opinion of Sir H. Davy, concerning the necessity of the pre- sence of water, or its elements, to ' the consti- tution of acids. He conceived that many acids are ternary compounds of a radical with oxy- gen and hydrogen; but that the two latter ingredients do not necessarily exist in them in the state of water. Oil of vitriol, for instance, in this view, instead of consisting of 81.5 real B 2 AC I ACI acid, and lfi.5 water in 100 parts, may be regarded as a compound of 32.6 sulphur -(- 65.2 oxygen, -f- 2.2 hydrogen. When it is saturated with an alkaline base, and exposed to heat, the hydrogen unites to its equivalent quantity of oxygen, to form water, which evaporates, and the remaining oxygen and the sulphur combine with the base. But when the acid is made to act on a metal, the oxygen partly unites to it, and hydrogen alone escapes. " Nitric acid, in its highest state of con- centration, is not a definite compound of real acid, with about a fourth of its weight of water, but a ternary compound of nitrogen, oxygen, and hydrogen. Phosphoric acid is a, triple compound of phosphorus, oxygen, and hydrogen; and phosphorous acid is the proper binary compound of phosphorus and oxygen. The oxalic, tartaric, and other vege- table acids, are admitted to be ternary com- pounds of carbon, oxygen, and hydrogen ; and are therefore in strict conformity to the doc- trine now illustrated. " A relation of the elements of bodies to acidity is thus discovered different from what has hitherto been proposed. When a series of compounds exist, which have certain com- mon characteristic properties, and when these compounds all contain a common element, we conclude, with justice, that these proper- ties are derived more peculiarly from the ac- tion of this element. On this ground Lavoi- sier inferred, by an ample induction, that oxygen is a principle of acidity. Berthollet brought into view the conclusion, that it is not exclusively so, from the examples of prus- sic acid and sulphuretted hydrogen. In the latter, acidity appeared to be produced by the action of hydrogen. The discovery by Gay Lussac, of the compound radical cyanogen, and its conversion into prussic acid by the addition of hydrogen, confirmed this conclu- sion ; and the discovery of the relations of iodine still further established it. And now, if the preceding views are just, the system must be still further modified. While each of these conclusions is just to a certain ex- tent, each of them requires to be limited in some of the cases to which they are applied ; and while acidity is sometimes exclusively connected with oxygen, sometimes with hy- drogen, the principle must also be admitted, that it is more frequently the result of their combined operation. u There appears even sufficient reason to infer, that, from the united action of these elements, a higher degree of acidity is ac- quired than from the action of either alone. Sulphur affords a striking example of this. With hydrogen it forms a weak acid. With oxygen it also forms an acid, which, though of superior energy, still does not display much power. With hydrogen and oxygen it seems to receive the acidifying influence of both, and its acidity is proportionally ex- alted. " Nitrogen, with hydrogen, forms a com- pound altogether destitute of acidity, and possessed even of qualities the reverse. With oxygen, in two definite proportions, it forms oxides ; and it is doubtful if, in any propor- tion, it can establish with oxygen an insulated acid. But with oxygen and hydrogen in union it forms nitric acid, a compound more per- manent, and of energetic action." It is needless to give at more detail Dr. Murray's speculations, which, supposing them plausible in a theoretical point of view, seem barren in practice. It is sufficiently singular, that, in an attempt to avoid the transforma- tions, which, on his notion of the chloridic theory, a little moisture operates on common salt, instantly changing it from chlorine and sodium into muriatic acid and soda, Dr. Murray should have actually multiplied, with one hand, the very difficulties which he had laboured, with the other, to remove. He thinks it doubtful if nitrogen and oxy- gen can alone form an insulated acid. Hy- drogen he conceives essential to its energetic action. What, we may ask then, exists in dry nitre, which contains no hydrogen ? Is it nitric acid, or merely two of its elements, in want of a little water to furnish the re- quisite hydrogen ? The same questions may be asked relative to the sulphate of potash. Since he conceives hydrogen necessary to communicate full force to sulphuric and ni- tric acids, the moment they lose their water they should lose their saturating power, and become incapable of retaining caustic potash in a neutral state. Out of this dilemma he may indeed try to escape, by saying, that moisture or hydrogen is equally essential to alkaline strength, and that therefore the same desiccation or de-hydrogenation which impairs the acid power, impairs also that of its alka- line antagonist. The result must evidently be, that in a saline hydrate or solution, we have the reciprocal attractions of a strong acid and alkali, while, in a dry salt, the attractive forces are those of relatively feeble bodies. On this hypothesis, the difference ought -to be great between dry and moistened sulphate of potash. Carbonic acid he admits to be desti- tute of hydrogen ; yet its saturating power is very conspicuous in neutralizing dry lime. Again, oxalic acid, by the last analysis of Berzelius, as well as my own, contains no hydrogen. It differs from the carbonic only in the proportion of its two constituents. And ox- alic acid is appealed to by Dr. Murray as a proof of the superior acidity bestowed by hydrogen. On what grounds he decides carbonic to be a feebler acid than oxalic, it is difficult to see. By Berthollet's test of acidity, the former is more energetic than the latter in the proportion of 100 to about 58 ; for these numbers are inversely as the quantity of each ACI 5 ACI requisite to saturate a given base. If he be inclined to reject this rule, and appeal to the decomposition of the carbonates by oxalic acid, as a criterion of relative acid power, let us adduce his own commentary on the sta- tical affinities of Berthollet, where he ascribes such changes, not to a superior attraction in the decomposing substance, but to the elastic tendency of that which is evolved. Ammonia separates magnesia from its muriatic solution at common temperatures ; at the boiling heat of water, magnesia separates ammonia. Car- bonate of ammonia, at temperatures under 230, precipitates carbonate of lime from the muriate; at higher temperatures, the inverse decomposition takes place with the same in- gredients. If the oxalic be a more energetic acid than the carbonic, or rank higher in the scale of acidity, then, on adding to a given weight of liquid muriate of lime a mixture of oxalate and carbonate of ammonia, each in equivalent quantity to the calcareous salt, oxalate of lime ought alone to be separated. It will be found, on the contrary, by the test of acetic acid, that as much carbonate of lime will precipitate as is sufficient to unsettle these speculations. Finally, dry nitre, and dry sulphate of potash, are placed, by this supposition, in as mysterious a predicament as dry muriate of soda in the chloridic theory. Deprived of hydrogen, their acid and alkali are enfeebled or totally changed. With a little water, both instantly recruit their powers. In a word, the solid sulphuric acid of Nordhausen, and the dry potash of potassium, are alone suf- ficient to subvert this whole hypothesis of hy- drogenation. We shall introduce, under the head of alkali, some analogous speculations by Dr. Murray on the influence of the elements of water on that class of bodies. Edin. Phil. Trans, vol. viii. part 2d. After these observations on the nature of acidity, we shall now state the general proper- ties of the acids. 1. The taste of these bodies is for the most part sour, as their name denotes ; and in the stronger species it is acrid and corrosive. 2. They generally combine with water in every proportion, with a condensation of vo- lume and evolution of heat. 3. With a few exceptions they are vola- tilized or decomposed at a moderate heat. 4. They usually change the purple colours of vegetables to a bright red. 5. They unite in definite proportions with the alkalis, earths, and metallic oxides, and form the important class of salts. This may be reckoned their characteristic and indis- pensable property. The powers of the dif- ferent acids were originally estimated by their relative causticity and sourness, afterwards by the scale of their attractive force towards any particular base, and next by the quantity of the base which they could respectively neutralize. But Berthollet proposed the converse of this last criterion as the measure of their powers. " The power witl? which they can exercise their acidity," he estimates " by the quantity of each of the acids which is required to produce the same effect, viz. to saturate a given quantity of the same alkali." It is therefore the capacity for saturation of each acid, which, in ascertaining its acidity, according to him, gives the comparative force of the affinity to which it is owing. Hence he infers, that the affinity of the different acids for an alkaline base, is in the inverse ratio of the ponderable quantity of each of them which is necessary to neutralize an equal quantity of the same alkaline base. An acid is, therefore, in this view, the more powerful, when an equal weight can saturate a greater quantity of an alkali. Hence, all those sub- stances which can saturate the alkalis, and cause their properties to disappear, ought to be classed among the acids ; in like manner, among the alkalis should be placed all those which, by their union, can saturate acidity. And the capacity for saturation being the measure of this property, it should be em- ployed to form a scale of the comparative power of alkalis as well as that of acids. However plausible, a priori, the opinion of this illustrious philosopher may be, that the smaller the quantity of an acid or alkali re- quired to saturate a given quantity of its an- tagonist principle, the higher should it rank in the scale of power and affinity, it will not, however, accord with chemical phenomena. 100 parts of nitric acid are saturated by about 364 f niagnesia, and 52^ of lime. Hence, by Berthollet's rule, the powers of these earths ought to be inversely as their quantities, viz. and ; yet the very opposite effect ooi oz takes place, for lime separates magnesia from nitric acid. And in the present example, the difference of effect cannot be imputed to the difference of force with which the substances tend to assume the solid state. We have therefore at present no single acidifying principle, nor absolute criterion of the scale of power among the different acids ; nor is the want of this of great importance. Experiment furnishes us with the order of de- composition of one acido-alkaline compound by another acid, whether alone, or aided by temperature ; and this is all which practical chemistry seems to require. Before entering on the particular acids, we shall here describe the general process by which M. Thenard has lately succeeded in communicating to many of them apparently a surcharge of oxygen, and thus producing a supposed new class of bodies, the oxygenized acids, which are, in reality, combinations of the ordinary acids with oxygenized water, or with the deutoxide of hydrogen. The ACI G ACI first notice of these new compounds ap- peared in the Ann. de Chimie et Physique, viii. 306, for July 1818 ; since which time several additional communications of a very interesting nature have been made by the same celebrated chemist. He has likewise formed a compound of water with oxygen, in which the proportion of the latter principle is doubled, or 616 times its volume is added. The methods of oxygenizing the liquid acids and water agree in this, that deutoxide of barium is formed first of all, from which the above liquids, by a subsequent process, derive their oxygen. He prescribes the following precautions, without which success will be only partial : 1. Nitrate of barytes should first be ob- tained perfectly pure, and above all, free from iron and manganese. The most certain means of procuring it is to dissolve the ni- trate in water, to add to the solution a small excess of barytes water, to filter and crys- tallize. 2. The pure nitrate is to be decom- posed by heat. This ought not to be done in a common earthenware retort, because it contains too much of the oxides of iron and manganese, but in a perfectly white porcelain retort. Four or five pounds of nitrate of barytes may be decomposed at once, and the process will require about three hours. The barytes thus procured will contain a consider- able quantity of silex and alumina ; but it will have only very minute traces of manga- nese and iron, a circumstance of essential importance. 3. The barytes divided by a knife into pieces as large as the end of the thumb, should then be placed in a luted tube of glass. This tube should be long, and large enough to contain from 2^ to 3-J Ibs. It is to be surrounded with fire, and heated to dull redness, and then a current of dry oxygen gas is to be passed through it How- ever rapid the current, the gas is completely absorbed ; so that when it passes by the small tube, which ought to terminate the larger one, it may be concluded that the deutoxide of barium is completed. It is, however, right to continue the current for seven or eight minutes more. Then the tube being nearly cold, the deutoxide, which is of a light grey colour, is taken out, and pre- served in stoppered bottles. When this is moistened it falls to powder, without much increase of temperature. If in this state it be mixed with seven or eight times its weight of water, and a dilute acid be poured in, it dissolves gradually by agitation, without the evolution of any gas. The solution is neutral, or has no action on turnsole or turmeric. When we add to this solution the requisite quantity of sulphuric acid, a copious preci- pitate of barytes falls, and the filtered liquor is merely water, holding in solution the oxy- genized acid, or deutoxide of hydrogen, com- bined with the acid itself. The class of acids has been distributed into three orders, according as they are derived from the mineral, the vegetable, or the animal kingdom. But a more specific distribution is now requisite. They have also been ar- ranged into those which have a single, and those which have a compound basis or radical. But this arrangement is not only vague, but liable in other respects to considerable objec- tions. The chief advantage of a classification is to give general views to beginners in the study, by grouping together such substances as have analogous properties or composition. These objects, it is hoped, will be tolerably well attained by the following divisions and subdivisions. Division 1st, Acids from inorganic nature, or which are procurable without having re- course to animal or vegetable products. Division 2d, Acids elaborated by means of organization. The first group is subdivided into three families : 1st, Oxygen acids ; 2d, Hydrogen acids ; 3d, Acids destitute of both these sup- posed acidifiere. Family 1st Oxygen acids. Section 1st, Non-metallic. 1. Boracic. 12. lodic. 2. Bromic. 13. lodo-Sulphuric. 3. Carbonic. 14. Hypophosphorous. 4. Chloric. 15. Phosphorous. 5. Perchloric? 16. Phosphatic. 6. Chloro-Carbonic. 17- Phosphoric. 7- lodous. 18. Hyposulphurous. 8. Nitrous. 19. Sulphurous. 9. Hyponitric. 20. Hyposulphuric. 10. Nitric. 21. Sulphuric. 11. Hyponitrous. 22. Cyanic. Section 2d, Oxygen acids. Metallic. 1. Arsenic. 6. Columbic. 2. Arsenious. 7 Molybdic. 3. Antimonious. 8. Molybdous. 4. Antimonic. 9. Titanic. 5. Chromic. 10. Tungstic. Family 2d. Hydrogen acids. 1. Fluoric. 7- Hydroselenic. 2. Hydriodic. 8. Hydroprussic, or 3. Hydrochloric, or Hydrocyanic. Muriatic. 9. Hydrosulphurous. 4. Ferroprussic. 10. Hydrotellurous. 5. Fluo-titanic. 11. Hydroxantbic. 6. Hydro-bromic. 12. Sulphuroprussic. Family 3d. Acids without oxygen or hydrogen. 1. Chloriodic. 3. Fluoboric. 2. Chloroprussic, or 4. Fluosilicic. Chlorocyanic. Division 2d. Acids of organic origin. 1. Abietic. 3. Acetic. 2. Aceric. 4. Amniotic. ACI ACI 5. Benzoic. 32. Melassic? 6. Boletie. 33. MeUitic. 7. Butyric. 34. Moroxylic. 8. Camphoric. 35. Mucic. 9. Capric, Caproic. 36. Nanceic ? 10. Caseic. 37. Nitro-leucic. 11. Cevadic. 38. Nitro-saccharic. 12. Cholesteric. 39. Okie. 13. Citric. 40. Oxalic. 14. Croconic. 41. Pectic. 15. Delphinic. 42. Phocenic. 16. Ellagic? 43. Pinic. 17. Formic. 44. Purpuric. 18. Fulminic. 45. Pyrocitric. 19. Fungic. 46. Pyrolithic. 20. Gallic. 47. Pyromalic. 21. Hydroxanthic. 48. Pyrotartaric. 22. Igasuric. 49. Rosacic. 23. Kinic. 50. Saclactic. 24. Laccic. 51. Sebacic? 25. Lactic. 52. Suberic. 26. Lampic. 53. Succinic. 27. Lithic or Uric. 54. Sulpho- 28. Malic. naphthalic. 29. Meconic. 55. Sulphovinic ? 30. Menispermic ? 56. Tartaric. 31. Margaric. The acids of this last division are all decompos- able at a red heat, and afford generally carbon, hydrogen, oxygen, and in some few cases also nitrogen. The mellitic is found like amber in wood coal, and, like it, is undoubtedly of organic origin. We shall treat of them all in alphabetical order, only joining those acids to- gether which graduate, so to speak, into each other, as hyposulphurous, sulphurous, hypo- sulphuric, and sulphuric. ACID (AB1ETIC). A substance, crys- tallizing in square plates, soluble in alcohol, and capable of forming salts with the alkalis, extracted from the resin of the Pinus Abies by M. Baup of Lausanne. ACID (ACERIC). A peculiar acid said to exist in the juice of the maple. It is decom- posed by heat, like the other vegetable acids. ACID (ACETIC). The same acid which, in a very dilute and somewhat impure state, is called vinegar. This acid is found combined with potash in the juices of a great many plants ; particu- larly the sambucus nigra, phoenix dactflife- ra, galium verum, and rhus typhinus. Sweat, urine, and even fresh milk contain it. It is frequently generated hi the stomachs of dys- peptic patients. Almost all dry vegetable substances, and some animal, subjected in close vessels to a red heat, yield it copiously. It is the result likewise of a spontaneous fer- mentation, to which liquid vegetable, and ani- mal matters are liable. Strong acids, as the sulphuric and nitric, develop the acetic by their action on vegetables. It was long sup- posed on the authority of Boerhaave, that the fermentation which forms vinegar is uni- formly preceded by the vinous. This is a mistake. Cabbages sour in water, making sour crout; starch, in starch-makers' sour waters ; and dough itself, without any pre- vious production of wine. The varieties of acetic acids known in com- merce are four: 1st, Wine vinegar; 2d, Malt vinegar ; 3d, Sugar vinegar ; 4th, Wood vinegar. We shall describe first the mode of making these commercial articles, and then that of extracting the absolute acetic acid of the chemist, either from these vinegars, or directly from chemical compounds, of which it is a constituent The following is the plan of making .vine- gar at present practised in Paris. The wine destined for vinegar is mixed in a large tun with a quantity of wine lees, and the whole being transferred into cloth-sacks, placed within a large iron-bound vat, the liquid matter is extruded through the sacks by super- incumbent pressure. What passes through is put into large casks, set upright, having a small aperture in their top. In these it is exposed to the heat of the sun in summer, or to that of a stove in winter. Fermentation supervenes in a few days. If the heat should then rise too high, it is lowered by cool air, and the addition of fresh wine. In the skil- ful regulation of the fermentative temperature consists the art of making good wine vinegar. In summer, the process is generally completed in a fortnight : in winter, double the time is requisite. The vinegar is then run off into barrels, which contain several chips of birch- wood. In about a fortnight it is found to be clarified, and is then fit for the market. It must be kept in close casks. The manufacturers at Orleans prefer wine of a year old for making vinegar. But if by age the wine has lost its extractive mat- ter, it 'does not readily undergo the acetous fermentation. lu this case, acetification, as the French term the process, may be deter- mined, by adding slips of vines, bunches of grapes, or green woods. It has been asserted, that alcohol, added to fermentable liquor, does not increase the product of vinegar. But this is a mistake. Stahl observed long ago, that if we moisten roses or lilies with alcohol, and place them in vessels in which they are stirred from time to time, vinegar will be formed. He also informs us, if after abstracting the citric acid from lemon juice by crabs' eyes (carbonate of lime), we add a little alcohol to the supernatant liquid, and place the mixture in a proper temperature, vinegar will be formed. Chaptal says, that two pounds of weak spirits, sp. gr. 0.985, mixed with 300 grains of beer yeast, and a little starch water pro- duced extremely strong vinegar. The acid was developed on the 5th day. The same quantity of starch and yeast, without the spirit, fermented more slowly, and yielded a weaker vinegar. A slight motion is found ACI ACI to favour the formation of vinegar, and to endanger its decomposition after it is made. Chaptal ascribes to agitation the operation of thunder ; though it is well known, that when the atmosphere is highly electrified, beer is apt to become suddenly sour, without the concussion of a thunder-storm. In cellars exposed to the vibrations occasioned by the rattling of carriages, vinegar does not keep well. The lees, which had been deposited by means of isinglass and repose, are thus jum- bled into the liquor, and make the fermenta- tion recommence. Almost all the vinegar of the north of France being prepared at Orleans, the manu- facture of that place has acquired such cele- brity, as to render their process worthy of a separate consideration. The Orleans casks contain nearly 400 pints of wine. Those which have been al- ready used are preferred. They are placed in three rows, one over another, and in the top have an aperture of two inches diameter, kept always open. The wine for acetification is kept in adjoining casks, containing beech shavings, to which the lees adhere. The wine thus clarified is drawn off to make vine- gar. One hundred pints of good vinegar, boiling hot, are first poured into each cask, and left there for eight days. Ten pints of wine are mixed in, every eight days, till the vessels are full. The vinegar is allowed to remain in this state fifteen days, before it is exposed to sale. The used casks, called mothers, are never emptied more than half, but are successively filled again, to acetify new portions of wine. In order to judge if the mother works, the vinegar makers plunge a spatula into the li- quid ; and according to the quantity of froth which the spatula shows, they add more or less wine. In summer, the atmospheric heat is sufficient. In winter, stoves heated to about 75 Fahr. maintain the requisite temperature in the manufactory. In some country districts, the people keep in a place where the temperature is mild and equable, a vinegar cask, into which they pour such wine as they wish to acetify ; and it is always preserved full, by replacing the vine- gar drawn off, by new wine. To establish this household manufacture, it is only neces- sary to buy at first a small cask of good vinegar. At Gand a vinegar from beer is made, in which the following proportions of grain are found to be most advantageous : 1880 Paris Ibs. malted barley. 700 . wheat. 500 buck wheat. These grains are ground, mixed, and boiled, along with twenty-seven casks-full of river water, for three hours. Eighteen casks of good beer for vinegar are obtained. By a subsequent decoction, more fermentable liquid is extracted, which is mixed with the former. The whole brewing yields 3000 English quarts. In this country, vinegar is usually made from malt. By mashing with hot water, 100 gallons of wort are extracted in less than two hours from 1 boll of malt. When the liquor has fallen to the temperature of 75 Fahr. 4 gallons of the barm of beer are added. After thirty-six hours it is racked off into casks, which are laid on their sides, and exposed, with their bung-holes loosely covered, to the influence of the sun in sum- mer; but in winter they are arranged in a stove-room. In three months this vinegar is ready for the manufacture of sugar of lead. To make vinegar for domestic use, however, the process is somewhat different. The above liquor is racked off into casks placed upright, having a false cover pierced with holes fixed at about a foot from their bottom. On this a considerable quantity of rape, or the refuse from the makers of British wine, or otherwise a quantity of low priced raisins, is laid. The liquor is turned into another barrel every twenty -four hours, in which time it has begun to grow warm. Sometimes, indeed, the vine- gar is fully fermented, as above, without the rape, which is added towards the end, to com- municate flavour. Two large casks are in this case worked together, as is described long ago by Boerhaave, as follows : " Take two large wooden vats, or hogsheads, and in each of these place a wooden grate or hurdle, at the distance of a foot from the bot- tom. Set the vessel upright, and on the grate place a moderately close layer of green twigs, or fresh cuttings of the vine. Then fill up the vessel with the footstalks of grapes, com- monly called the rape, to the top of the vessel, which must be left quite open. " Having thus prepared the two vessels, pour into them the wine to be converted into vinegar, so as to fill one of them quite up, and the other but half full. Leave them thus for twenty-four hours, and then fill up the half filled vessel with liquor from that which is quite full, and which will now in its turn only be left half full. Four-and-twenty hours afterwards repeat the same operation, and thus go on, keeping the vessels alternately full and half full during twenty-four hours till the vinegar be made. On the second or third day there will arise in the half filled vessel, a fermentative motion, accompanied with a sensible heat, which will gradually in- crease from day to day. On the contrary, the fermenting motion is almost imperceptible in the full vessel ; and as the two vessels are alternately full and half full, the fermentation is by this means in some measure interrupted, and is only renewed every other day in each vessel. " When this motion appears to have' entirely ceased, even in the half filled vessel, it is a sign ACI 9 ACI that the fermentation is finished ; and therefore the vinegar is then to be put into casks close stopped, and kept in a cool place. " A greater or less degree of warmth ac- celerates or checks this, as well as the spiritu- ous fermentation. In France it is finished in about fifteen days, during the summer; but if the heat of the air be very great, and exceed the twenty-fifth degree of Reaumur's thermometer (885 Fahr.), the half filled vessel must be filled up every twelve hours ; because, if the fermentation be not so checked in that time, it will become violent, and the liquor will be so heated, that many of the spirituous parts, on which the strength of the vinegar depends, will be dissipated, so that nothing will remain after the fermentation but a vapid liquor, sour indeed, but effete. The better to prevent the dissipation of the spi- rituous parts, it is a proper and usual pre- caution to close the mouth of the half filled vessel, in which the liquor ferments, with a cover made of oak wood. As to the full vessel, it is always left open, that the ah- may act freely on the liquor it contains ; for it is not liable to the same inconveniences, because it ferments very slowly." Good vinegar may be made from a weak syrup, consisting of 18 oz. of sugar to every gallon of water. The yeast and rape are to be here used as above described. Whenever the vinegar (from the taste and flavour) is considered to be complete, it ought to be decanted into tight barrels or bottles, and well secured from access of air. A momen- tary ebullition before it is bottled is found favourable to its preservation. In a large manufactory of malt vinegar, a considerable revenue is derived from the sale of yeast to the bakers. Vinegar obtained by the preceding methods has more or less of a brown colour, and a peculiar but rather grateful smell. By distil- lation in glass vessels the colouring matter, which resides in a mucilage, is separated, but the fragrant odour is generally replaced by an empyreumatic one. The best French wine vinegars, and also some from malt, contain a little alcohol, which comes over early with the watery part, and renders the first product of distillation scarcely denser, sometimes even less dense, than water. It is accordingly rejected. Towards the end of the distillation the empyreuma increases. Hence only the intermediate portions are retained as distilled vinegar. Its specific gravity varies from 1.005 to 1.015, while that of common vinegar of equal strength varies from 1.010 to 1.025. A crude vinegar has been long prepared for the calico printers, by subjecting wood in iron retorts to a strong red heat. The following arrangement of apparatus has been found to answer well. A series of cast-iron cylinders, about 4 feet diameter, and 6 feet long, arc built horizontally in brick- work, so that the flame of one furnace may play round about two cylinders. Both ends project a little from the brick, work. One of them has a disc of cast-iron well fitted and firmly bolted to it, from the centre of which disc an iron tube about 6 inches diameter proceeds, and enters at a right angle the main tube of refrigeration. The diameter of this tube may be from 9 to 14 inches, according to the number of cylinders. The other end of the cylinder is called the mouth of the retort. This is closed by a disc of iron, smeared round its edge with clay-lute, and secured in its place by wedges. The charge of wood for such a cylinder is about 8 cwt. The hard woods, oak, ash, birch, and beech, are alone used. Fir does not answer. The heat is kept up during the day-time, and the fur- nace is allowed to cool during the night. Next morning the door is opened, the char- coal removed, and a new charge of wood is introduced. The average product of crude vinegar called pyrolignous acid is 35 gallons. It is much contaminated with tar ; is of a deep brown colour; and has a sp. gr. of 1.025. Its total weight is therefore about 300 Ibs. But the residuary charcoal is found to weigh no more than one-fifth of the wood employed. Hence nearly one-half of the ponderable matter of the wood is dissipated in incondensable gases. Count Rumford states, that the charcoal is equal in weight to more than four-tenths of the wood from which it is made. The Count's error seems to have arisen from the slight heat of an oven to which his wood was exposed in a glass cylinder. The result now given is the expe- rience of an eminent manufacturing chemist at Glasgow. The crude pyrolignous acid is rectified by a second distillation in a copper still, in the body of which about 20 gallons of viscid tarry matter are left from every 100. It has now become a transparent brown vi- negar, having a considerable empyreumatic smell, and a sp. gr. of 1.013. Its acid powers are superior to those of the best house- hold vinegar, in the proportion of 3 to 2. By redistillation, saturation with quicklime, evaporation of the liquid acetate to dryness, and gentle torrefaction, the empyreumatic matter is so completely dissipated, that on decomposing the calcareous salt by sulphuric acid, a pure, perfectly colourless, and grateful vinegar rises in distillation. Its strength will be proportional to the concentration of the de- composing acid. The acetic acid of the chemist may be prepared in the following modes: 1st, Two parts of fused acetate of potash with one of the strongest oil of vitriol yield, by slow dis- tillation from a glass retort into a refriger- ated receiver, concentrated acetic acid. A small portion of sulphurous acid, which con- taminates it, may be removed by redistilla- tion, from a little acetate of lead. 2d, Or ACI ACI 4 parts of good sugar of lead, with 1 part of sulphuric acid treated in the same way, afford a slightly weaker acetic acid. 3d, Gently calcined sulphate of iron, or green vitriol, mixed with sugar of lead in the proportion of 1 of the former to 2J of the latter, and carefully distilled from a porcelain retort into a cooled receiver, may be also cdnsidered a good economical process. Or without dis- tillation, if 100 parts of well dried acetate of lime be cautiously added to 60 parts of strong sulphuric acid, diluted with 5 parts of water, and digested for 24 hours, and strained, a good acetic acid, sufficiently strong for every ordinary purpose, will be obtained. The distillation of acetate of copper or of leader se, has also been employed for ob- taining strong acid. Here, however, the product is mixed with a portion of the fra- grant pyro-acetic spirit, which it is trouble- some to get rid of. Undoubtedly the best process for the strong acid is that first de- scribed., and the cheapest the second or third. When of the utmost possible strength its sp. gravity is 1.062. At the temperature of 50 F. it assumes the solid form, crystalliz- ing in oblong rhomboidal plates. It has an extremely pungent odour, affecting the nos- trils arid eyes even painfully, when its vapour is incautiously snuffed up. Its taste is emi- nently acid and acrid. It excoriates and in- flames the skin. The purified wood vinegar, which is used for pitekles and culinary purposes, has com- monly a specific gravity of about 1.009; when it is equivalent in acid strength to good wine or malt vinegar of 1.014. It contains about -3 of its weight of absolute acetic acid, and of water. An excise duty of 4d. is levied on every gallon of vinegar of the above strength. This, however, is not estimated directly by its sp. gr. but by the sp. gr. which results from its saturation with quicklime. The decimal number of the sp. gv. of the calcareous acetate is nearly double that of the pure wood vinegar. Thus 1.009 ia vinegar, becomes 1.018 in liquid acetate. But the vinegar of fermentation =. 1.014 will become only 1.023 in acetate, from which, if 0.005 be subtracted for mucilage or ex- tractive, the remainder will agree with the den- sity of the acetate from wood. A glass hy- drometer of Fahrenheit's construction is used for finding the specific gravities. It consists of a globe about 3 inches diameter, having a little ballast ball drawn out beneath, and a stem above of about 3 inches long, contain- ing a slip of paper with a transverse line in the middle, and surmounted with a little cup for receiving weights or poises. The experi- ments on which this instrument, called an Acetometer, is constructed, have been detailed in the sixth volume of the Journal of Science. They do not differ essentially from those of Mollerat. The following points were deter- mined by this chemist. The acid of sp. gr. 1.063 requires 2 times its weight of crys- tallized subcarbonate of soda for saturation, whence M. Thenard regards it as a com- pound of 1 1 of water, and 89 of real acid in the 100 parts. Combined with water in the proportion of 100 to 112.2, it does not change its density, but it then remains liquid several degrees below the freezing point of water. By diluting it with a smaller quan- tity of water, its sp. gr. augments, a circum- stance peculiar to this acid. It is 1.079, or at its maximum, when the water forms one- third of the weight of the acid. Ann. de Chimie, torn. 66. The following table is given by Messrs. Taylor, as the basis of their acetometer : Revenue proof acid, called by the manu- facturer No. 24. sp. gr. 1.0085 contains real acid in 100, 5 1.0170 .... 10 1.0257 . - - 15 1.0320 . - - 20 1.0470 - 30 1.0580 - - - 40 An acetic acid of very considerable strength may also be prepared by saturating perfectly dry charcoal with common vinegar, and then distilling. The water easily comes off, and is separated at first; but a stronger heat is required to expel the acid. Or by exposing vinegar to very cold air, or to freezing mix- tures, its water separates in the state of ice, the interstices of which are occupied by a strong acetic acid, which may be procured by draining. The acetic acid or radical vinegar of the apothecaries, in which they dissolve a little camphor, or fragrant essential oil, has a specific gravity of about 1.070. It contains fully 1 part of water to 2 of the crystallized acid. The pungent smelling salt consists of sulphate of potash moistened with that acid. Acetic acid acts on tin, iron, zinc, copper, and nickel ; and it combines readily with the oxides of many other metals, by mixing a so- lution of their sulphates with that of an acetate of lead. This acid, as it exists in the acetates of barytes and of lead, has been analyzed by MM. Gay Lussac and Thenard, and also by Berzelius. Gay Lussac found 50.224 carbon, 5.629 hydrogen, and 44.147 oxygen ; or, in other terms, 50.224 carbon, 46.911 of water, or its elementary constituents, and 2.863 oxygen in excess. Berzelius, 46.83 carb. 6.33 hydr. and 46.82 oxygen in the hundred parts. Their methods are described under VE- GETABLE (ANALYSIS). By saturating known weights of bases with acetic acid, and ascertaining the quantity of acetates obtained after cautious evaporation to dryness, Ber- zelius obtained with lime (3.56) 6.5 for the prime equivalent of acetic acid, and with yel- ACI II ACI low oxide of lead 6.432. Recent researches, which will be published in a detailed form, induce me to fix the prime of acetic acid at 7.0. Acetic acid dissolves resins, gum resins, camphor, and essential oils. Its odour is employed in medicine to relieve nervous headache, fainting fits, or sickness occasioned by crowded rooms. In a slightly dilute state, its application has been found to check he- morrhagy from the nostrils. Its anticon- tagious powers are now little trusted to. It is very largely used in calico printing. Mo- derately rectified pyrolignous acid has been recommended for the preservation of animal food ; but the empyreumatic taint it com- municates to bodies immersed in it, is not quite removed by their subsequent ebullition in water. See ACID (PYROLIGNOUS.) Acetic acid and common vinegar are some- times fraudulently mixed with sulphuric acid to give them strength. This adulteration may be detected by the addition of a little chalk, short of their saturation. With pure vinegar the calcareous base forms a limpid solution, but with sulphuric acid a white insoluble gypsum. Muriate of barytes is a still nicer test. British fermented vinegars are allowed by law to contain a little sulphuric acid, but the quantity is frequently exceeded. Copper is discovered in vinegars by supersaturating them with ammonia, when a fine blue colour is produced; and lead by sulphate of soda, hydrosulphurets, and sulphuretted hydrogen. None of these should produce any change on genuine vinegar. See LEAD. Acetic acid dissolves deutoxide of barium without effervescence. By precipitating the barytes with sulphuric acid, there remains an oxygenized acid, which, being saturated with potash, and heated, allows a great quantity of oxygen gas to escape. There is disengaged at the same time a notable quantity of carbo- nic acid gas. This shows that the oxygen, when assisted by heat, unites in part with the carbon, and doubtless likewise with the hy- drogen of the acid. It is in fact acetic deut- oxide of hydrogen. Salts consisting of the several bases, united in definite proportions to acetic acid, are called acetates. They are characterized by the pun- gent smell of vinegar, which they exhale on the affusion of sulphuric acid ; and by their yielding on distillation in a moderate red heat a very light, odorous, and combustible liquid called pyro-acetic (SPIRIT) ; which see. They are all soluble in water ; many of them so much so as to be uncrystallizable. About 30 different acetates have been formed, of which only a very few have been applied to the uses of life. The acetic acid unites with all the alkalis and most of the earths, and with these bases it forms compounds, some of which are crys- tallizable. The salts it forms are distin- guished by their great solubility; their de- composition by fire, which carbonizes them; the spontaneous alteration of their solution; and their decomposition by a great number of acids, which extricate from them the acetic acid in a concentrated state. It unites likewise with most of the metallic oxides. With barytes, the saline mass, by spon- taneous evaporation, crystallizes in fine trans- parent prismatic needles, of a bitterish acid taste, which do not deliquesce when exposed to the air, but rather effloresce. With potash this acid unites, and forms a deliquescent salt scarcely crystallizable, called formerly foliated earth of tartar, and regene- rated tartar. The solution of this salt, even in closely stopped vessels, is spontaneously de- composed. With soda it forms a crystallizable salt, which does not deliquesce. The salt formed by dissolving chalk or other calcareous earth in distilled vinegar, has a sharp bitter taste, and appears in the form of silky crystals. The acetate of strontian has a sweet taste, is very soluble, and is easily decomposed by a strong heat. The salt formed by uniting vinegar with ammonia, anciently called spirit of Minde- rerus, is generally in a liquid state, and is commonly believed not to be crystallizable. It nevertheless may be reduced into the form of small needle-shaped crystals, when this liquor is evaporated to the consistence of a syrup. With magnesia the acetic acid forms a vis- cid saline mass, which does not shoot into crystals, but remains deliquescent, has a taste sweetish at first, and afterwards bitter, and is soluble in spirit of wine. Glucine is readily dissolved by acetic acid. This solution, as Vauquelin informs us, does not crystallize ; but is reduced by evaporation to a gummy substance, which slowly becomes dry and brittle ; retaining a kind of ductility for a long time. It has a saccharine and pretty strongly astringent taste, in which that of vinegar however is distinguishable. Yttria dissolves readily in acetic acid, and the solution yields by evaporation crystals of acetate of y ttria. These have commonly the form of thick six-sided plates, and are not altered by exposure to the air. Acetate of alumina is commonly made by adding gradually to a boiling solution of alum in water a solution of acetate of lead, till no further precipitate ensues. The sulphate of lead having subsided, decant the supernatant liquor, evaporate, and the acetate of alumina may be obtained in small needle-shaped crys- tals, having a strong styptic and acetous taste. This salt is of great use in dyeing and calico- printing. SeeAujMisrA. Acetate of zircone may be formed by pour- ing acetic acid on newly precipated zircone. It has an astringent taste. It does not crys- ACI ACI tallize ; but when evaporated to dryness, forms a powder, which does not attract moisture from the air. It is very soluble both in water and alcohol ; and is not so easily decomposed by heat as nitrate of zircone. Concerning the action of vinegar on alcohol, see ETHER. M. Vauquelin has found that acetic acid may be combined with volatile oils. See OILS (VOLATILE.) See SPIRIT (PYRO-ACETIC). Vinegar dissolves the true gums, and partly the gum resins, by means of digestion. See SALT, for a tabular view of the con- stitution of the ACETATES. ACID (AMNIOTIC). On evaporating the liquor amnii of the cow to one- fourth, Vauquelin and Buniva found, that crystals form in it by cooling. These crystals when washed with a little water, are white and shining, slightly acid to the taste, redden lit- mus paper, and are a little more soluble in hot than cold water. With the alkalis this acid forms very soluble salts, but it does not de- compose the carbonate without the assistance of heat. Dr. Prout could not find this acid in the amniotic liquor of the cow, though he sought for it with much pains. Hence its existence is questionable. ACIDS (ANTIMONIC AND ANTI- MONIOUS). See ANTIMONY. ACID (ARSENIC). We are indebted to the illustrious Scheele for the discovery of this acid, though Macquer had before noticed its combinations. It may be obtained by various methods. If six parts of nitric acid be poured on one of the concrete arsenious acid, or white arsenic of the shops, in the pneumato-chemical apparatus, and heat be applied, nitrous gas will be evolved, and a white concrete substance, differing in its properties from the arsenious acid, will remain in the retort. This is the arsenic acid. It may equally be procured by means of aqueous chlorine, or by heating concentrated nitric acid with twice its weight of the solution of the arsenious acid in muri- atic acid. The concrete acid should be exposed to a dull red heat for a few minutes. In either case an acid is obtained, that does not crys- tallize, but attracts the moisture of the air, lias a sharp caustic taste, reddens blue vegetable colours, is fixed in the fire, and of the specific gravity of 3.391. If the arsenic acid be exposed to a red heat in a glass retort, it melts and becomes transparent, but assumes a milky hue on cooling. If the heat be increased, so that the retort begins to melt, the acid boils, and sublimes into the neck of the retort. If a covered crucible be used instead of a glass retort, and a violent heat applied, the acid boils strongly, and in a quarter of an hour begins to emit fumes. These, on being re- ceived in a glass bell, are found to be arsenious acid ; and a small quantity of a transparent- glass, difficult to fuse, will be found lining the sides of the crucible. This is arseniate of alumina. Combustible substances decompose this acid, and eliminate metallic arsenic. If pure arsenic acid be diluted with a small quantity of water, and hydrogen gas, as it is evolved by the action of sulphuric acid on iron, be received into this transparent solu- tion, the liquor grows turbid, and a blackish precipitate is formed, which being well washed with distilled water, exhibits all the pheno- mena of arsenic. Sometimes, too, a blackish- grey oxide of arsenic is found in this process. If sulphuretted hydrogen gas be employed instead of simple hydrogen gas, water and a sulphuret of arsenic are obtained. With phosphorus, phosphoric acid is ob- tained, and a phosphuret of arsenic, which sublimes. According to Lagrange, two parts of water are sufficient to dissolve one of arsenic acid. It cannot be crystallized by any means; but on evaporation, assumes a thick honey-like consistence. Arsenic acid combines with the earthy and alkaline bases, and forms salts very different from those furnished by the arsenious acid. All these arseniates are decomposable by charcoal, which separates arsenic from them by means of heat. Berzelius, from the result of accurate expe- riments on the arseniates of lead and barytes, infers the prime equivalent of arsenic acid to be 14.4569, oxygen being 1.0. On this supposition, . Berzelius's insoluble salts will consist of two primes of base and one of acid ; and the acid itself will be a com- pound of 5 of oxygen = 5, + 9.5 of the me- tallic base 14.5 ; for direct experiments have shown it to consist of 100 metal, and about 53 oxygen. But 153 : 100 : : 14.5 : 9.5 nearly. While Proust and Berzelius concur in as- signing the proportion of 53 oxygen to 100 metal in this acid, Thenard states its com- position at 56.25 to 100, and Dr. Thomson at 61.4 to 100. By the latter authority, its prime equivalent becomes 4.75 metal + 3 oxygen = 7-75; and that of arsenious acid 4.75 + 2 6.75. All its salts, with the exception of those of potash, soda, and ammonia, are insoluble in water ; but except arseniate of bismuth, and one or two more, very soluble in an excess of arsenic acid. Hence, after barytes or oxide of lead has been precipitated by this acid, its farther addition redissolves the pre- cipitate. This is a useful criterion of the acid, joined to its reduction to the metallic state by charcoal, and the other characters already detailed. Sulphuric acid decomposes the arseniates at a low temperature, but the sulphates are decomposed by arsenic acid at a ACT 13 ACI red heat, owing to the greater fixity of the latter. Phosphoric, nitric, muriatic, and fluoric acids, dissolve, and probably convert into subsalts all the arseniates. The whole of them, as well as arsenic acid itself when decomposed at a red heat by charcoal, yield the characteristic garlic smell of the metallic vapour. Nitrate of silver gives a pulverulent brick-coloured precipitate, with arsenic acid. The acid itself does not disturb the transpa- rency of a solution of sulphate of copper ; but a neutral arseniate gives with it a bluish- green precipitate ; with sulphate of cobalt a dirty red ; and with sulphate of nickel, an apple-green precipitate. These precipitates redissolve, on adding a small quantity of the acid which previously held them in solution, Orfila says, that arsenic acid gives, with acetate of copper, a bluish-white precipitate, but that it exercises no action either on the muriate or acetate of cobalt; but with the ammonia-muriate it gives a rose-coloured pre- cipitate, Arsenic acid ought to be accounted a more violent poison than even the arsenious. According to Mr. Brodie it is absorbed, and occasions death by acting on the brain and the heart. Arsenic acid saturated with potash does not crystallize. The bin-arseniate of potash is fabricated on the great scale in Saxony, by fusing toge- ther equal parts of nitre and arsenious acid; dissolving the melted mass, and crystallizing the salt. The crystals are large. By the analysis of M. Berzelius, they consist of arsenic acid 63.87, potash 26.16, water 9.97. Ann. de Chim. et de Phys. xix. 366. By Dr. Thomson their composition is, arse- nic acid 68.5, potash 26.5, water 5. Mit- scherlich's statement is in accordance with Berzelius's equivalent number. With lime water this acid forms a precipi- tate of arseniate of lime, soluble in an excess of its acid, though insoluble alone. If arsenic acid be saturated with magnesia, a thick substance is formed near the point of saturation. Arseniate of barytes is insoluble, and un- crystallizable, but soluble in an excess of the acid. It consists, by Berzelius, of 57 barytes -{- 43 arsenic acid. The bin-arseniate of barytes crystallizes. It is made by dissolving the neutral salt in arsenic acid. It contains twice the quantity of acid which exists in the former. With soda in sufficient quantity to saturate it, arsenic acid forms a salt crystallizable like the acidulous arseniate of potash. To form the neutral arseniate, carbonate of soda should be added to the acid, till the mixture be de- cidedly alkaline. This salt crystallizes from the concentrated solution. It is much more soluble in hot than in cold water. Pelletier says, that the crystals are hexaedral prisms terminated by planes perpendicular to their axis. 1 00 parts of arseniate of soda are composed, by the experiments of Berzelius, of arsenic acid 29.29, soda 15.88, water 54.84. The triple salt, called arseniate of potash and soda, easily crystallizes. It consists, according to the same chemist, of arseniate of potash, 30.24 Arseniate of soda, 26.65 Water, 44.11 The bin-arseniate of soda is obtained by add- ing arsenic acid to the solution of the neutral salt, till the mixture no longer gives a preci- pitate with muriate of barytes. It is very soluble in water. It consists of Arsenic acid, 63.16 Soda, 17.13 Water, 19.71 Combined with ammonia, arsenic acid forms a salt affording rhomboidal crystals analogous to those of the nitrate of soda. To form this salt, we must add ammonia to the concentrated solution of the acid, till a precipitate fall. On heating the solution, the precipitate is dissolved. If we set the liquid aside, taking care that too much of the ammonia does not exhale, there is formed, after some time, large and beautiful crystals of the neutral salt. The crystals which some- times fall during the cooling of this solution are a sub-arseniate. The neutral arseniate of ammonia decomposes in the air. It consists of Arsenic acid, 65.28 Ammonia, 19.44 Water, 15.28 Mitscherlich. Bin-arseniate of ammonia is formed by adding arsenic acid to ammonia till litmus paper be strongly reddened by the solution, and till it no longer precipitates muriate of barytes. We then obtain by evaporation crystals which do not change on exposure to the air. It consists, according to Berzelius, of arsenic acid 72-30, ammonia 10.77, water 16.93, in 100 parts. The arseniate of soda and ammonia is formed by mixing the two separate arseniates ; and the compound salt gives crystals with brilliant faces. If we redissolve the crystals, and then recrystallize, we should add a little ammonia, otherwise the salt will be acidulous from the escape of some ammonia. Arsenic acid saturated with alumina forms a thick solution. By the assistance of a strong fire, as Four- croy asserts, arsenic acid decomposes the alkaline and earthy sulphates, even that of barytes. Lagrange, however, denies that it acts on any of the neutral salts, except the sulphate of potash and soda, the nitrate of potash, and the muriates of soda and ammonia, and this by means of heat. It does not act on the phosphates. Arsenic acid does not act on gold or pla- tina: neither does it on mercury or silver without the aid of a strong heat; but it oxidizes copper, iron, lead, tin, zinc, bismuth, ACI ACI antimony, cobalt, nickel, manganese, and arsenic. This acid is not used in the arts, at least directly, though indirectly it forms a part of some compositions used in dyeing. It is like- wise one of the mineralizing acids combined by nature with some of the metallic oxides. See SALTS (TABLE OF). ACID (ARSENIOUS). Fourcroy was the first who distinguished by this name the white arsenic of the shops, which Scheele had proved to be a compound of the metal arsenic with oxygen. This acid, which is one of the most virulent poisons known, frequently occurs in a native state, if not very abundantly ; and it is ob- tained in roasting several ores, particularly those of cobalt. In the chimneys of the fur- naces where this operation is conducted, it generally condenses in thick semitransparent masses ; though sometimes it assumes the form of a powder, or of little needles, in which state it was formerly called flowers of arsenic. The arsenious acid reddens the most sen- sible blue vegetable colours, though it turns the syrup of violets green- On exposure to the air it becomes opaque, and covered with a slight efflorescence. Thrown on incan- descent coals, it evaporates in white fumes, with a strong smell of garlic. In close vessels it is volatilized ; and, if the heat be strong, vitrified. The result of this vitrification is a transparent glass, capable of crystallizing in tetraedra, the angles of which are truncated. It is easily altered by hydrogen and carbon, which deprive it of its oxygen at a red heat, and reduce the metal, the one forming water, the other carbonic acid, with the oxygen taken from it ; as it is by phosphorus, and by sulphur, which are in part converted into acids by its oxygen, and in part form an arsenical phosphuret or sulphuret with the arsenic reduced to the metallic state. Hence Margraaf and Pelletier, who particularly ex- amined the phosphurets of metals, have as- serted they might be formed with arsenious acid. Its specific gravity is 3.7. It is soluble in thirteen times its weight of boiling water, but requires eighty times its weight of cold. The solution crystallizes and the acid assumes the form of regular tetrae- dons according to Fourcroy ; but according to Lagrange, of octaedrons, .and these fre- quently varying in figure by different laws of decrement. It crystallizes much better by slow evaporation than by simple cooling. The solution is very acrid, reddens blue colours, unites with the earthy bases, and de- composes the alkaline sulphurets. Arsenious acid is also soluble in oils, spirits, and alco- hol ; the last taking up from 1 to 2 per cent. It is composed by Berzelius of 9.5 of metal -f- 3 oxygen ; and its prime equivalent is therefore 12.5. But Dr. Thomson considers it, as a compound of 4.75 metal -f- 2 oxygen = 6.75. Dr. Wollaston first observed, that when a mixture of it with quicklime is heated in a glass tube, at a certain temperature, ignition suddenly pervades the mass, and metallic arsenic sublimes. As arseniate of lime is found at the bottoin of the tube, we perceive that a portion of the arsenious acid is robbed of its oxygen, to complete the acidification of the rest. The action of the other acids upon the arse- nious is very different from that which they exert on the metal arsenic. By boiling, sul- phuric acid dissolves a small portion of it, which is precipitated as the solution cools. The nitric acid does not dissolve it, but by the help of heat converts it into arsenic acid. Neither the phosphoric nor the carbonic acid acts upon it; yet it enters into a vitreous combination with the phosphoric and boracic acids. The muriatic acid dissolves it by means of heat, and forms with it a volatile compound, which water precipitates ; and aqueous chlo- rine acidifies it completely, so as to convert it into arsenic acid. The arsenious acid combines with the earthy and alkaline bases. The earthy arseniates possess little solubility ; and hence the solu- tions of barytes, strontian, and lime, form precipitates with that of arsenious acid. With the fixed alkalis the arsenious acid forms viscid arsenites, which do not crystal- lize, and which are decomposable by fire, the arsenious acid being volatilized by the heat. With ammonia it forms a salt capable of crystallization. Neither the earthy nor alkaline arsenites have yet been much examined. The nitrates act on the arsenious acid in a very remarkable manner. On treating the nitrates and arsenious acid together, the ni- trous acid, or nitrous vapour, is extricated in a state very difficult to be confined, as Kunc- kel long ago observed : part of its oxygen is absorbed by the arsenious acid; it is thus converted into arsenic acid, and an arseniate is left in the retort. The same phenomena take place on detonating nitrates with arse- nious acid; for it is still sufficiently com- bustible to produce a detonation, in which no sparks are seen, it is true, but with commo- tion and effervescence; and a true arseniate remains at the bottom of the crucible. It was in this way chemists formerly prepared their fixed arsenic, which was the acidulous arseniate of potash. The nitrate of ammonia exhibits different phenomena in its decom- position by arsenious acid, and requires con- siderable precaution. Pelletier, having mixed equal quantities, introduced the mixture into a large retort of coated glass, placed in a re- verberatory furnace, with a globular receiver. He began with a very slight fire ; for the de- composition is so rapid, and the nitrous va- pours issue with such force, that a portion of ACI 15 ACI the arsenious acid is carried off undecomposed, unless you proceed very gently. If due care be taken that the decomposition proceeds more slowly, nitrous acid first conies over; if the fire be continued, or increased, ammonia is next evolved; and lastly, if the fire be urged, a portion of oxide of arsenic sublimes in the form of a white powder, and a vitreous mass remains in the retort, which powerfully attacks and corrodes it. This is arsenic acid. The chlorate of potash, too, by completely oxid- izing the arsenious acid, converts it into arsenic acid, which, by the assistance of heat, is ca- pable of decomposing the muriate of potash that remains. Arsenious acid is used in numerous in- stances in the arts, under the name of white arsenic, 01 of arsenic simply. In many cases it is reduced, and acts in its metallic state. Many attempts have been made to intro- duce it into medicine ; but as it is known to be one of the most violent poisons, it is pro- bable that the fear of its bad effects may de- prive society of the advantages it might afford in this way. An arsenite of potash was ex- tensively used by the late Dr. Fowler of York, who published a treatise on it, in intermittent and remittent fevers. He found it extremely efficacious in periodical headach, and as a tonic in nervous and other disorders. Exter- nally it has been employed as a caustic to ex- tirpate cancer, combined with sulphur, with bole, with antimony, and with the leaves of crowfoot ; but it always gives great pain, and is not unattended with danger. It has been more lately used as an alterative with advantage in chronic rheumatism. The symptoms which show the system to be arse- nifled are thickness, redness, and stiffness of the palpebrce, soreness of the gums, ptyalism, itching over the surface of the body, restless- ness, cough, pain at stomach, and headach. When the latter symptoms supervene, the ad- ministration of the medicine ought to be im- mediately suspended. It has also been recom- mended against chincough ; and has been used in considerable doses with success, to counter- act the poison of venomous serpents. Since it acts on the animal economy as a deadly poison in quantities so minute as to be insensible to the taste when diffused in water or other vehicles, it has been often given with criminal intentions and fatal effects. It be- comes therefore a matter of the utmost im- portance to present a systematic view of the phenomena characteristic of the poison, its operation, and consequences. 1st, It is a dense substance, subsiding speedily after agitation in water. I find its sp. gr. to vary from 3.728 to 3-730, which is a little higher than the number given above : 72 parts dissolve in 1000 of boiling water, of which 30 remain^in it after it cools. Cold water dissolves, however, only Q or $ of the preceding quantity. This water makes the syrup of violets green, and reddens litmus paper. Lime water gives a fine white preci- pitate with it of arsenite of lime, soluble in an excess of the arsenious solution ; sulphu- retted hydrogen gas, and hydrosulphuretted water, precipitate a golden yellow sulphuret of arsenic. By this means 100 1 000 of arseni- ous acid may be detected in water. This sul. phuret dried on a filter, and heated in a glass tube with a bit of caustic potash, is decom- posed in a few minutes, and converted into sulphuret of potash, which remains at the bottom, and metallic arsenic of a bright steel lustre, which sublimes, coating the sides of the tube. The hydrosulphurets of alkalis do not affect the arsenious solution, unless a drop or two of nitric or muriatic acid be poured in, when the characteristic golden yellow precipi- tate falls. Nitrate of silver is decomposed by the arsenious acid, and a very peculiar yellow arsenite of silver precipitates ; which, however, is apt to be redissolved by nitric acid, and therefore a very minute addition of ammonia is requisite. Even this, however, also, if in much excess, redissolves the silver precipitate. As the nitrate of silver is justly regarded as one of the best precipitant tests of arsenic, the mode of using it has been a subject of much discussion. This excellent test was first proposed by Mr. Hume of Long Acre, in May 1809. Phil. Mag. xxxiii. 401 The presence of muriate of soda indeed, in the arsenical solution, obstructs, to a certain degree, the operation of this reagent. But that salt is almost always present in the prl- mce vice, and is an usual ingredient in soups, and other vehicles of the poison. If, after the water of ammonia has been added, (by plunging the end of a glass rod dipped in it into the supposed poisonous liquid), we dip another rod into a solution of pure nitrate of silver, and transfer it into the arsenious so- lution, either a fine yellow cloud will be formed, or at first merely a white curdy pre- cipitate. But at the second or third immer- sion of the nitrate rod, a central spot of yel- low will be perceived surrounded with the white muriate of silver. At the next im- mersion this yellow cloud on the surface will become very conspicuous. Sulphate of soda does not interfere in the least with the silver test The ammoniaco-sulphate, or rather ammo- niaco- acetate of copper, added in a somewhat dilute state to an arseniou's solution, gives a fine grass-green and very characteristic precU pitate. This green arsenite of copper, well washed, being acted on by an excess of sul- phuretted hydrogen water, changes its colour, and becomes of a brownish-red. Ferro-prus- siate of potash changes it into a blood-red. Nitrate of silver converts lit into the yellow arsenite of silver. Lastly, if the precipitate be dried on a filter, and placed on a bit of burning coal, it will ACI 16 ACI diffuse a garlic odour. The cupreous test will detect n 0*660 of the weight of the arsenic in water. The voltaic battery, made to act by two wires on a little arsenious solution placed on a bit of window-glass, developes metallic arsenic at the negative pole ; and if this wire be copper, it will be whitened like tombac. We may here remark, however, that the most elegant mode of using all these preci- pitation reagents is upon a plane of glass ; a mode practised by Dr. Wollaston in general chemical research, to an extent, and with a success, which would be incredible in other hands than his. Concentrate by heat in a capsule the suspected poisonous solution, having previously filtered it if necessary. Indeed, if it be very much disguised with animal or vegetable matters, it is better first of all to evaporate to dryness, and by a few drops of nitric acid to dissipate the organic products. The clear liquid being now placed in the middle of the bit of glass, lines are to be drawn out from it in different directions. To one of these a particle of weak ammoniacal water being applied, the weak nitrate of silver may then be brushed over it with a hair pencil. By placing the glass in different lights, either over white paper or obliquely before the eye, the slightest change of tint will be perceived. The ammoniaco-acetate should be applied to another filament of the drop, deut-acetate of iron to a third, weak ammoniaco-acetate of co- balt to a fourth, sulphuretted water to a fifth, lime water to a sixth, a drop of violet-syrup to a seventh, and the two galvanic wires at the opposite edges of the whole. Thus with one single drop of solution many exact experi- ments may be made. But the chief, the decisive trial or expert- mentum crucls remains, which is to take a little of the dry matter, mix it with a small pinch of dry black flux, put it into a narrow glass tube sealed at one end, and after cleansing its sides with a feather, urge its bottom with a blowpipe till it be distinctly red-hot for a mi- nute. Then garlic fumes will be smelt, and the steel-lustred coating of metallic arsenic will be seen in the tube about one-fourth of an inch above its bottom. Cut the tube across at that point by means of a fine file, detach the scale of arsenic with the point of a penknife; put a fragment of it into the bottom of a small wine-glass along with a few drops of ammo- niaco-acetate of copper, and triturate them well together for a few minutes with a round-headed glass rod. The mazarine blue colour will soon be transmuted into a lively grass green, while the metallic scale will vanish. Thus we di- stinguish perfectly between a particle of me- tallic arsenic and one of animalized charcoal. Another particle of the scale may be placed between two smooth and bright surfaces of copper, with a touch of fine oil ; and whilst they are firmly pressed together, exposed to a red heat The tombac alloy will appear as a white stain. A third particle may be placed on a bit of heated metal, and held a little under the nostrils, when the garlic odour will be recognized. No danger can be apprehended, as the fragment need not exceed the tenth of a grain. It is to be observed, that one or two of the precipitation tests may be equivocal from ad- mixtures of various substances. Thus tinc- ture of ginger gives with the cupreous re-agent a green precipitate ; and the writer of this ar- ticle was at first led to suspect from that ap- pearance, that an empirical tincture, put into his hands for examination, did contain arsenic. But a careful analysis satisfied him of its ge- nuineness. Tea covers arsenic from the cu- preous test Such poisoned tea becomes by its addition of an obscure olive or violet red, but yields scarcely any precipitate. Sulphuretted hydrogen, however, throws down a fine yellow sulphuret of arsenic. To remove the colouring matter of a vege- table or animal kind Mr. Phillips has very properly recommended to mix the poisoned liquid with well washed animal charcoal (bone- black) and thereafter to filter, before applying the tests, 100 grains of black mixed with 500 of port wine, containing 1 grain of arsenious acid, became so de-coloured, as to admit of the application of tests. A good way of obviating all these sources of fallacy is to evaporate carefully to dryness, and expose the residue to heat in a glass tube. The arsenic sublimes, and may be afterwards operated on without ambiguity. M. Orfila has gone into ample details on the modifica- tions produced by wine, coffee, tea, broth, &c. on arsenical tests, of which a good tabular abstract is given in Mr. Thomson's London Dispensatory. But it is evident that the dif- ferences in these menstrua, as also in beers, are so great as to render precipitations and changes of colour by reagents very unsatis- factory witnesses in a case of life and death. Hence the method of evaporation above de- scribed should never be neglected. Should the arsenic be combined with oil, the mixture ought to be boiled with water, and the oil then separated by the capillary action of wick- threads. If with resinous substances, these may be removed by oil of turpentine, not by alcohol (as directed by Dr. Black), which is a good solvent of arsenious acid. It may more- over be observed, that both tea and coffee should be freed from their tannin by gelatin, which does not act on the arsenic, previous to the use of reagents for the poison. When one part of arsenious acid in watery solution is added to ten parts of milk, the sulphuretted hydrogen present in the latter, occasions the white colour to pass into a canary yellow ; the cupreous test gives it a slight green tint, and the nitrate of silver produces no visible change, though even more arsenic be added j but the ACI 17 ACI hydrosulphurets throw down a golden yellow, with the aid of a few drops of an acid. The liquid contained in the stomach of a rabbit poi- soned with a solution of 3 grains of arsenious acid, afforded a white precipitate with nitrate of silver, greyish white with lime water, green with the ammoniaco-sulphate, and deep yellow with sulphuretted hydrogen water. The preceding copious description of the habitudes of arsenious acid in different cir- cumstances is equally applicable to the solu- ble arsenites. Their poisonous operation, as well as that of the arsenic acid, has been satisfactorily referred by Mr. Brodie to the suspension of the functions of the heart and brain, occasioned by the absorption of these substances into the circulation, and their con- sequent determination to the nervous system and the alimentary canal. This proposition was established by numerous experiments on rabbits and dogs. Wounds were inflicted, and arsenic being applied to them, it was found that in a short time death supervened, with the same symptoms of inflammation of the stomach and bowels as if the poison had been swallowed. He divides the morbid affections into three classes : 1st, Those depending on the nervous system, as palsy at first of the posterior ex- tremities, and then of the rest of the body, convulsions, dilatation of the pupils, and ge- neral insensibility : 2d, Those which indicate disturbance in the organs of circulation : for example, the feeble, slow, and intermitting pulse, weak contractions of the heart im- mediately after death, and the impossibility of prolonging them, as may be done in sudden deaths from other causes, by artificial re- spiration : 3d, Lastly, Those which depend on lesion of the alimentary canal, as the pains of the abdomen, nauseas, and vomitings, in those animals which were suffered to vomit. At one time it is the nervous' system that is most remarkably affected, and at another the organs of circulation. Hence inflammation of the stomach and intestines ought not to be considered as the immediate cause of death, in the greater number of cases of poisoning by arsenic. However, should an animal not sink under the first violence of the poison, if the inflammation has had time to be de- veloped, there is no doubt that it may destroy life. Mr. Earle states, that a woman who had taken arsenic resisted the alarming sym- ptoms which at first appeared, but died on the fourth day. On opening her body the mu- cous membrane of the stomach and intestines was ulcerated to a great extent. Authentic cases of poison are recorded, where no trace of inflammation was perceptible in the primae vice. The effects of arsenic have been graphically represented by Dr. Black : " The symptoms produced by a dangerous dose of arsenic begin to appear in a quarter of an hour, or not much longer, after it is taken. First sickness, and great distress at stomach, soon followed by thirst, and burning heat in the bowels. Then come on violent vomiting, and severe colic pains, and excessive and painful purging. This brings on faintings with cold sweats, and other signs of great debility. To this succeed painful cramps, and contractions of the legs and thighs, and extreme weakness, and death." Similar results have followed the incautious sprinkling of schirrous ulcers with powdered arsenic, or the application of arsenical pastes. The following more minute specification of sym- ptoms is given by Orfila : " An austere taste in the mouth ; frequent ptyalism ; continual spitting j constriction of the pharynx and oeso- phagus ; teeth set on edge ; hiccups ; nausea ; vomiting of brown or bloody matter; anxiety; frequent fainting fits ; burning heat at the precordia ; inflammation of the lips, tongue, palate, throat, stomach ; acute pain of sto- mach, rendering the mildest drinks intoler- able ; black stools of an indescribable fcetor ; pulse frequent, oppressed, and irregular, some- times slow and unequal; palpitation of the heart; syncope; unextinguishable thirst; burning sensation over the whole body, re- sembling a consuming fire ; at times an icy coldness; difficult respiration; cold sweats; scanty urine, of a red or bloody appearance ; altered expression of countenance ; a livid circle round the eyelids ; swelling and itching of the whole body, which becomes covered with livid spots, or with a miliary eruption ; prostration of strength ; loss of feeling, espe- cially in the feet and hands ; delirium, con- vulsions, sometimes accompanied with an in- supportable priapism ; loss of the hair ; sepa- ration of the epidermis ; horrible convulsions ; and death." It is uncommon to observe all these fright- ful symptoms combined in one individual ; sometimes they are altogether wanting, as is shown by the following case, related by M. Chaussier : a robust man of middle age swal- lowed arsenious acid in large fragments, and died without experiencing other symptoms than slight syncopes. On opening his sto- mach, it was found to contain the arsenious acid in the very same state in which he had swallowed it. There was no appearance what- ever of erosion or inflammation in the intes- tinal canal. Etmuller mentions a young girl's being poisened by arsenic, and whose stomach and bowels were sound to all appearance, though the arsenic was found in them. In general, however, inflammation does extend along the whole canal, from the mouth to the rectum. The stomach and duodenum present frequently gangrenous points, eschars, perforations of all their coats; the villous coat in particular, by this and all other cor- rosive poisons, is commonly detached, as if it were scraped off or reduced into a paste of a reddish-brown colour. From these considera- AC I 18 AC I tions we may conclude, that from the existence or non-existence of intestinal lesions, from the extent or seat of the symptoms alone, the phy- sician should not venture to pronounce defini- tively on the fact of poisoning. The result of Mr. Brodie's experiments on brutes teaches, that the inflammations of the intestines and stomach are more severe when the poison has been applied to an external wound, than when it has been thrown into the stomach itself. The best remedies against this poison in the stomach are copious draughts of bland liquids of a mucilaginous consistence, to inviscate the powder, so as to procure its complete ejection by vomiting. Sulphuretted hydrogen condensed in water is the only direct antidote to its virulence ; Orfila having found, that when dogs were made to swallow that liquid, after getting a poisonous dose of arsenic, they recovered, though their aesophagus was tied to prevent vomiting ; but when the same dose of poison was administered in the same cir- cumstances, without the sulphuretted water, that it proved fatal. When the viscera are to be subjected after death to chemical investigation, a ligature ought to be thrown round the aasophagus and the beginning of the colon, and the interme- diate stomach and intestines removed. Their liquid contents should be emptied into a basin ; and thereafter a portion of hot water introduced into the stomach, and worked tho- roughly up and down this viscus, as well as the intestines. After filtration, a portion of the liquid should be concentrated by evaporation in a porcelain capsule, and then submitted to the proper reagents above described. We may also endeavour to extract from the stomach by digestion in boiling water, with a little ammonia, the arsenical impregnation, which has been sometimes known to adhere in mi- nute particles with wonderful obstinacy. This precaution ought therefore to be attended to. The heat will dissipate the excess of ammonia in the above operation ; whereas by adding potash or soda, as prescribed by the German chemists, we introduce animal matter in al- kaline solution, which complicates the investi- gation. The matters rejected from the patient's bowels before death should not be neglected. These, generally speaking, are best treated by cautious evaporation to dryness : but we must beware of heating the residuum to 400, since at that temperature, and perhaps a little under it, the arsenious acid itself sub- limes. Vinegar, hydroguretted alkaline sulphurets, and oils, are of no use as counterpoisons. Indeed, when the arsenic exists in substance in the stomach, even sulphuretted hydrogen water is of no avail, however effectually it neutralize an arsenious solution. Syrups, lin- seed tea, decoction of mallows, or tragacanth, and warm milk, should be administered as copiously as possible, and vomiting provoked by tickling the fauces with a feather. Clys- ters of a similar nature may be also employed. Many persons have escaped death by having taken the poison mixed with rich soups ; and it is well known, that when it is prescribed as a medicine, it acts most beneficially when given soon after a meal. These facts have led to the prescription of butter and oils ; the use of which is, however, not advisable, as they screen the arsenical particles from more proper menstrua, and even appear to aggravate its virulence. Morgagni, in his great work on the seats and causes of disease, states, that at an Italian feast the dessert was purposely sprinkled over with arsenic instead of flour. Those of the guests who had previously ate and drank little, speedily perished ; those who had their stomachs well filled, were saved by vomiting. He also mentions the case of three children who ate a vegetable soup poisoned with arsenic. One of them, who took only two spoons-full, had no vomiting, and died ; the other two, who had eaten the rest, vo- mited, and got well. Should the poisoned patient be incapable of vomiting, a tube of caoutchouc, capable of being attached to a syringe, may be had recourse to. The tube first serves to introduce the drink, and to withdraw it after a few instants. The following tests of arsenic and corrosive sublimate have been lately proposed by Brug- nateili : take the starch of wheat boiled in water until it is of a proper consistence, and recently prepared ; to this add a sufficient quantity of iodine to make it of a blue colour ; it is afterwards to be diluted with pure water until it becomes of a beautiful azure. If to this, some drops of a watery solution of arsenic be added, the colour changes to a reddish hue, and finally vanishes. The solution of corrosive sublimate poured into iodine and starch, produces almost the same change as arsenic ; but if to the fluid acted on by the arsenic we add some drops of sulphuric acid, the original blue colour is restored with more than its original brilliancy, while it does not restore the colour to the corrosive sublimate mixture. See SALT. ACID (BENZOIC). The usual method of obtaining this acid affords a very elegant and pleasing example of the chemical process of sub- limation. For this purpose a thin stratum of powdered benzoin is spread over the bottom of a glazed earthen pot, to which a tall conical paper covering is fitted : gentle heat is then to be applied to the bottom of the pot, which fuses the benzoin, and fills the apartment with a fra- grant smell, arising from a portion of essential oil and acid of benzoin, which are dissipated into the air ; at the same time the acid itself rises very suddenly in the paper head, which may be occasionally inspected at the top, ACI 19 ACI though with some little care, because the fumes will excite coughing. This acid sublimate is condensed in the form of long needles, or straight filaments of a white co- lour, crossing each other in all directions. When the white acid ceases to rise, the cover may be changed, a new one applied, and the heat raised : more flowers of a yellowish colour will then rise, which require a second sub- limation to deprive them of the empyreumatic oil they contain. The sublimation of the acid of benzoin may be conveniently performed by substituting an inverted earthen pan instead of the paper cone. In this case the two pans should be made to fit, by grinding on a stone with sand, and they must be luted together with paper dipped in paste. This method seems pre- ferable to the other, where the presence of the operator is required elsewhere ; but the paper head can be more easily inspected and changed. The heat applied must be very gentle, and the vessels ought not to be separated till they have become cool. The quantity of acid obtained in these methods differs according to the management, and probably also from difference of purity, and in other respects, of the balsam itself. It usually amounts to no more than about one- eighth part of the whole weight. Indeed Scheele says, not more than a tenth or twelfth. The whole acid of benzoin is obtained with greater certainty in the humid process of Scheele : this consists in boiling the powdered balsam with lime water, and afterwards sepa- rating the lime by the addition of muriatic acid. Twelve ounces of water are to be poured upon four ounces of slaked lime ; and, after the ebullition is over, eight pounds, or ninety-six ounces, more of water are to be added : a pound of finely-powdered benzoin being then put into a tin vessel, six ounces of the lime water are to be added, and mixed well with the powder; and afterwards the rest of the lime water in the same gradual manner, because the benzoin would coagulate into a mass, if the whole were added at once. This mixture must be gently boiled for half an hour with constant agitation, and afterwards suffered to cool and subside during an hour. The supernatant liquor must be decanted, and the residuum boiled with eight pounds more of lime water; after which the same process is to be once more repeated : the re- maining powder must be edulcorated on the filter by affusions of hot water. Lastly, all the decoctions, being mixed together, must be evaporated to two pounds, and strained into a glass vessel. This fluid consists of the acid of benzoin combined with lime. After it is become cold, a quantity of muriatic acid must be added, with constant stirring, until the fluid tastes a little sourish. During this time the last-mentioned acid unites with the lime, and forms a soluble salt, which remains suspended, while the less soluble acid of benzoin, being disengaged, falls to the bottom in powder. By repeated affusions of cold water upon the filter, it may be deprived of the muriate of lime and muriatic acid with which it may hap- pen to be mixed. If it be required to have a shining appearance, it may be dissolved in a small quantity of boiling water, from which it will separate in silky filaments by cooling. By this process the benzoic acid may be pro- cured from other substances, in which it exists. Mr. Hatchell has shown, that, by digesting benzoin in hot sulphuric acid, very beautiful crystals are sublimed. This is perhaps the best process for extracting the acid. If we concentrate the urine of horses or cows, and pour muriatic acid into it, a copious precipitate of benzoic acid takes place. This is the cheapest source of it. The acid of benzoin is so inflammable, that it burns with a clear yellow flame with- out the assistance of a wick. The sublimed flowers in their purest state, as white as or- dinary writing paper, were fused into a clear transparent yellowish fluid, at the two hun- dred-and-thirtieth degree of Fahrenheit's thermometer, and at the same time began to rise in sublimation. It is probable that a heat somewhat greater than this may be required to separate it from the resin. It is strongly disposed to take the crystalline form in cooling. The concentrated sulphuric and nitric acids dissolve this concrete acid, and it is again separated without alteration, by adding water. Other acids dissolve it by the assistance of heat, from which it separates by cooling, unchanged. It is plentifully solu- ble in ardent spirit, from which it may like- wise be separated by diluting the spirit with water. It readily dissolves in oils, and ir* melted tallow. If it be added in a small proportion to this last fluid, part of the tal- low congeals before the rest, in the form of white opaque clouds. If the quantity of acid be more considerable, it separates in part by cooling, in the form of needles or feathers. In the destructive distillation of tallow, benzoic acid is said to be formed. At the temperature of boiling water, oil of turpentine dissolves about its own weight of benzoic acid, but the solution becomes concrete on cooling. Pure benzoic acid is in the form of a light powder, evidently crystallized in fine needles, the figure of which is difficult to be deter- mined from their smallness. It has a white and shining appearance ; but when contami- nated by a portion of volatile oil, is yellow or brownish. It is not brittle, as might be expected from its appearance, but has rather a kind of ductility and elasticity, and, on rubbing in a mortar, becomes a sort of paste. Its taste is acrid, hot, acidulous, and bitter. c 2 ACI 20 ACI It reddens the infusion of litmus, but not syrup of violets. It has a peculiar aromatic smell, but not strong unless heated. This, however, appears not to belong to the acid ; for Mr. Giese informs us, that on dissolving the benzoic acid in as little alcohol as possible, filtering the solution, and precipitating by water, the acid will be obtained pure, and void of smell, the odorous oil remaining dissolved in the spirit. Its specific gravity is 0.667. It is not perceptibly altered by the air, and has been kept in an open vessel twenty years with- out losing any of its weight. None of the combustible substances have any effect on it ; but it may be refined by mixing it with char- coal powder and subliming, being thus ren- dered much whiter and better crystallized. It is not very soluble in water. Wenzel and Lichtenstein say four hundred parts of cold water dissolve but one, though the same quan- tity of boiling water dissolves twenty parts, nineteen of which separate on cooling. Berzelius states the composition of benzoic acid to be carbon 74.41, oxygen 20.43, and hydrogen 5.16 in 100. From the benzoate of lead, he deduces the prime equivalent to be 14.893. By my experiments, its components are carbon 66.74, oxygen 28.32, and hydrogen 4.94; and by saturation with ammonia its prime equivalent appeared to be 14.5, to oxygen 1. The benzoic acid unites without much difficulty with the earthy and alkaline bases. The benzoate of barytes is soluble and crystallizes. That of lime is very soluble in water, though much less in cold than in hot, and crystallizes on cooling. The benzoate of magnesia is soluble, crystallizable, and a little deliquescent. That of alumina is very soluble, crystallizes in dendrites, is deliquescent, and has an acerb and bitter taste. The benzoate of potash crystallizes on cooling in little com- pacted needles. The benzoate of soda is very crystallizable, very soluble, and not deliques- cent like that of potash, but it is decomposable by the same means. It is sometimes found native in the urine of graminivorous qua- drupeds, but by no means so abundantly as that of lime. The benzoate of ammonia is volatile, and decomposable by all the acids and all the bases. The solutions of all the tenzoates, when drying on the sides of a vessel wetted with them, form dendritical crystal- lizations. Trommsdorf found in his experiments, that benzoic acid united readily with metallic oxides. The benzoates are all decomposable by heat, which, when it is slowly applied, first separates a portion of the acid in a vapour, that condenses in crystals. The soluble ben- zoates are decomposed by the powerful acids, which separate their acid in a crystalline form. The benzoate of ammonia has been proposed by Berzelius as a reagent for precipitating red oxide of iron from perfectly neutral solu- tions. See SALTS (TABLE of.) ACID (BOLETIC). An acid extracted from the expressed juice of the boletus pseudo igniarius by M. Braconnot This juice, con- centrated to a syrup by a very gentle heat, was acted on by strong alcohol. What re- mained was dissolved in water. When ni- trate of lead was dropped into this solution, a white precipitate fell, which, after being well washed with water, was decomposed by a current of sulphuretted hydrogen gas. Two different acids were found in the liquid after filtration and evaporation. One in perma- nent crystals was BOLETIC acid; the other was a small proportion of phosphoric acid. The former was purified by solution in alcohol, and subsequent evaporation. It consists of irregular four-sided prisms, of a white colour, and permanent in the air. Its taste resembles cream of tartar; at the temperature of 68 it dissolves in 180 times its weight of water, and in 45 of alcohol. Ve- getable blues are reddened by it. Red oxide of iron, and the oxides of silver and mercury, are precipitated by it from their solutions in nitric acid ; but lime and barytes waters are not affected. It sublimes when heated, in white vapours, and is condensed in a white powder. Ann. de Chimie, Ixxx. ACID (BORACIC). The salt composed of this acid and soda had long been used both in medicine and the arts under the name of borax, when Homberg first obtained the acid separate in 1702, by distilling a mixture of borax and sulphate of iron, Lemery the younger soon after discovered that it could be obtained from borax equally by means of the nitric or muriatic acid ; Geoffroy detected soda in borax ; and at length Baron proved by a number of experiments, that borax is a com- pound of soda and a peculiar acid. To procure the acid, dissolve borax in hot water, and filter the solution ; then add sul- phuric acid by little and little, till the liquid has a sensibly acid taste. Lay it aside to cool, and a great number of small shining laminated crystals will form. These are the boracic acid. They are to be washed with cold water, and drained upon paper. Boracic acid thus procured is in the form of thin irregular hexagonal scales, of a silvery whiteness, having some resemblance to sper- maceti, and the same kind of greasy feel. It has a sourish taste at first, then makes a bit- terish cooling impression, and at last leaves an agreeable sweetness. Pressed between the teeth, it is not brittle but ductile. It has no smell ; but, when sulphuric acid is poured on it, a transient odour of musk is produced. Its specific gravity in the form of scales is 1.479; after it has been fused, 1-803. It is not altered by light. Exposed to the fire, it swells up, from losing its water of crystal- lization, and in this state is called calcined ACI ACI boracic acid. It melts a little before it is red- hot, without perceptibly losing any water, but it does not flow freely till it is red, and then less than the borate of soda. After this fusion it is a hard transparent glass, becoming a little opaque on exposure to the air, without abstracting moisture from it, and unaltered in its properties, for on being dissolved in boiling water it crystallizes as before. This glass is used in the composition of false gems. Boiling water scarcely dissolves one-fiftieth part, and cold water much less. When this solution is distilled in close vessels, part of the acid rises with the water, and crystallizes in the receiver. It is more soluble in alcohol, and alcohol containing it burns with a green flame, as does paper dipped in a solution of boracic acid. Crystallized boracic acid is a compound of 57 parts of acid and 43 of water. The honour of discovering the radical of loracic acid is divided between Sir H. Davy and MM. Gay Lussac and Thenard. The first, on applying his powerful voltaic battery to it, obtained a chocolate-coloured body in small quantity; but the two latter chemists, by acting on it and potassium in equal quantities, at a low red heat, formed boron and sub-borate of potash. For a small experiment, a glass tube will serve, but on a greater scale a copper tube is to be preferred. The potassium and boracic acid, perfectly dry, should be intimately mixed before exposing them to heat. On withdraw- ing the tube from the fire, allowing it to cool, and removing the cork which loosely closed its mouth, we then pour successive portions of water into it, till we detach or dissolve the whole matter. The water ought to be heated each time. The whole collected liquids are allowed to settle; when, after washing the precipitate till the liquid ceases to affect syrup of violets, we dry the boron in a capsule, and then put it into a phial out of contact of air. Boron is solid, tasteless, inodorous, and of a greenish-brown colour. Its specific gravity is somewhat greater than water. The prime equivalent of boracic acid has been inferred from the borate of ammonia, to be about 2.7 or 2.8; oxygen being 1.0; and it probably consists of 2.0 of oxygen -\- 0.8 of boron. But by MM. Gay Lussac and The- nard, the proportions would be 2 of boron to 1 of oxygen. The boracic acid has a more powerful at- traction for lime than for any other of the bases, though it does not readily form borate of lime by adding a solution of it to lime water, or decomposing by lime water the so- luble alkaline borates. In either case an in- sipid white powder, nearly insoluble, which is the borate of lime, is however precipitated. The borate of barytes is likewise an insoluble, tasteless, white powder. Bergman has observed, that magnesia, thrown by little and little into a solution of boracic acid, dissolved slowly, and (he liquof on evaporation afforded granulated crystals without any regular form : that these crystals were fusible in the fire without being decom- posed ; but that alcohol was sufficient to se- parate the boracic acid from the magnesia. If however some of the soluble magnesian salts be decomposed by alkaline borates in a state of solution, an insipid and insoluble borate of magnesia is thrown down. It is probable, therefore, that Bergman's salt was a borate of magnesia dissolved in an excess of boracic acid ; which acid being taken up by the alcohol, the true borate of magnesia was precipitated in a white powder, and mistaken by him for magnesia. One of the best known combinations of this acid is the native magnesio-borate of Kalk- berg, near Lunenburg. See BORACITE. The borate of potash is but little known. With soda the boracic acid forms a salt of considerable use in the arts, and long known by the name of borax. According to M. Arfwredson, borax consists in the dry or calcined state of acid 68.9, soda 31.1 in 100. It was analyzed by mixing it with three or four tunes its weight of finely powdered fluor spar, free from silica, and a sufficient quantity of sulphuric acid. On eva- porating the mixture, and exposing it to a red heat, all the boracic acid was expelled as fluo- boric acid gas, and from the resulting sulphate of soda the quantity of this alkaline base was inferred. Gmelin found borax to contain in the crys- tallized state 46.6 per cent, of water ; and in the dry state he regards it as a compound of two parts by weight of acid and one of base. Borax, therefore, instead of being called, as heretofore, the sub-borate of soda, should be viewed as a bi-borate. From M. Arfwredson's analysis the prime equivalent of boracic acid would seem to be 4.4, and from M. Gmelin's 4. Dr. Thomson makes it only 3. More recently M. Soubeirons finds borax to consist of acid 67.584, base 32.416; whence the equivalent of boracic acid comes out 4.175. Borate of ammonia forms in small rhom- boidal crystals, easily decomposed by fire ; or in scales, of a pungent urinous taste, which lose the crystalline form, and grow brown on exposure to the air. The boracic acid unites with silex by fu- sion, and forms with it a solid and permanent vitreous compound. The boracic acid has been found in a dis- engaged state in several lakes of hot mineral waters near Monte Rotondo, Berchiaio, and Castellonuovo in Tuscany, in the proportion of nearly nine grains in a hundred of water, by M. HoefFer. M. Mascagni also found it adhering to schistus, on the borders of lakes, of an obscure white, yellow, or greenish co- lour, and crystallized in the form of needles* ACI ACI He has likewise found it in combination with ammonia. See SALT. ACID (BROMIC). When brome is agi- tated with a sufficiently concentrated solution of potash, two very different compounds are formed. Hydrobromate of potash remains dissolved in the liquid. A white powder pre- cipitates to the bottom of the vessel, of a crys- talline aspect, which fuses on red-hot coals like nitre, and is transformed by heat into bromide of potassium, with the disengagement of oxygen. This crystalline powder is bro- mate of potash. It is scarcely soluble in al- kohol, but in boiling water it dissolves pretty copiously, from which solution, by cooling, there fall down needles grouped together. When crystallized by evaporation, the bro- mate is deposited in crystalline plates, with little lustre. It deflagrates on ignited char- coal; and when mixed in powder with sub- limed sulphur, it detonates on being struck by a hammer. The solution of this salt yields a precipitate with nitrate of silver. This white and pul- verulent precipitate, blackening with difficulty on contact with light, is thereby distinguished from bromide of silver, which is yellowish, curdy, and easily affected by the sunbeams. The salts of lead, which produce an abun- dant crystalline precipitate, with hydrobromate of potash, have no effect on the bromate. Bromate of barytes forms acicular crystals, soluble in boiling water, scarcely so in cold water, and melting with a green flame on burning coals. On pouring dilute sulphuric acid into the solution of bromate of barytes, so as to preci- pitate the whole of the base, a dilute solution of bromic acid is obtained. The bromate of barytes is best obtained for this purpose by combining chlorine with bromc, and by placing this compound in contact with a solution of that earth. By slow evaporation the greater part of the water may be removed. It then acquires a syrupy consistence. If the temperature be raised higher with the view of expelling the water completely, one portion of the acid eva- porates, and the other is decomposed into oxygen and brome. The same change seems to ensue when the concentration is pushed too far by the action of a surface of sulphuric acid in vacuo. Water thus appears to be necessary to the constitution of bromic acid. This acid first reddens litmus paper, and soon thereafter deprives it of colour. It has scarcely any smell. Its taste is very acid, but not at all corrosive. The hydracids, as also those which are not saturated with oxygen, act with great energy on bromic acid. The sulphurous, muriatic, hydriodic, and hydrobromic acids decompose it, as well as sulphuretted hydrogen. From hydriodic acid, compounds of brome with chlorine and iodine, result. Bromic acid appears to be composed, in 100 parts, of 64.69 brome, 35.31 oxygen. If it contain, like the chloric acid, 5 atoms of oxygen, the atomic weight of brome would thus be 9.1 ; but other experiments seem to make it 9.5 ; whence the acid should consist of 65.52 brome, +34.48 oxygen. ACID (BUTYRIC). We owe the dis- covery of this acid to M. Chevreul. Butter, he says, is composed of two fat bodies, analo- gous to those of hog's lard, of a colouring principle, and a remarkable odorous one, to which it owes the properties that distinguish it from the fats, properly so called. This principle, which he has called butyric acid, forms well characterized salts with barytes, strontian, lime, the oxides of copper, lead, &c.; 100 parts of it neutralize a quantity of base which contains about 10 of oxygen. M. Chevreul has not explained his method of separating this acid from the other consti- tuents of butter. See Journ. de Pharmacis, iii. 80. ACID (CAMPHORIC). One part of camphor being introduced into a glass retort, four parts of nitric acid sp. gr. 1.33 are to be poured on it, a receiver adapted to the retort, and all the joints well luted. The retort is then to be placed on a sand-heat, and gradu- ally heated. During the process a consider- able quantity of nitrous gas, and of carbonic acid gas, is evolved ; and part of the camphor is volatilized, while another part seizes the oxygen of the nitric acid. When no more vapours are extricated, the vessels are to be separated, and the sublimed camphor added to the acid that remains in the retort. A like quantity of nitric acid is again to be poured on this, and the distillation repeated. This operation must be reiterated till the camphor is completely acidified. Twenty parts of nitric acid are sufficient to acidify one of camphor. When the whole of the camphor is acidified, it crystallizes in the remaining liquor. The whole is then to be poured out upon a filter, and washed with distilled water, to carry ofF the nitric acid it may have retained. The most certain indication of the acidification of the camphor is its crystallizing on the cooling of the liquor remaining in the retort. To purify this acid it must be dissolved in hot distilled water, and the solution, after being filtered, evaporated nearly to half, or till a slight pellicle forms; when the cam- phoric acid will be obtained in crystals on cooling. Camphoric acid has a slightly acid, bitter taste, and reddens infusion of litmus. It crystallizes; and the crystals upon the whole resemble those of muriate of ammonia. It effloresces on exposure to the atmosphere ; is not very soluble in cold water ; when placed on burning coals, it gives out a thick aromatic smoke, and is entirely dissipated ; and with a ACI ACI gentle heat melts, and is sublimed. It is so- luble in alcohol, and is not precipitated from it by water ; a property that distinguishes it from the benzoic acid. It unites easily with the earths and alkalis. See SALTS (TABLE OF). ACID (CAPRIC). An acid obtained by Chevreul from the soap, made with the butter of cow's milk, and so named because it has a smell like that of a goat. At 5 Fahr. it exists in the form of crystals. At 65 F. its sp. gr. is 0.910, 100 parts water dissolve only 0.12, but with alcohol, it combines in all pro- portions. ACID (CAPROIC). An acid similar to the preceding, and obtained from the same source. Its prime equivalent in the crystalline state seems to be about 11. ACID (CARBONIC). This acid, being a compound of carbon and oxygen, may be formed by burning charcoal ; but as it exists in great abundance ready formed, it is not ne- cessary to have recourse to this expedient. All that is necessary is to pour sulphuric or mu- riatic acid, diluted with five or six times its weight of water, on common chalk, which is a compound of carbonic acid and lime. An effervescence ensues ; carbonic acid is evolved in the state of gas, and may be received in the usual manner. Carbonic acid abounds in great quantities in nature, and appears to be produced in a variety of circumstances. It composes y^% of the weight of limestone, marble, calcareous spar, and other natural specimens of calcareous earth, from which it may be extricated either by the simple application of heat, or by the superior affinity of some other acid ; most acids having a stronger action on bodies than this. Water, under the common pressure of the at- mosphere, and at a low temperature, absorbs somewhat more than its bulk of fixed air, and then appears acidulous. If the pressure be greater, the absorption is augmented. It is to be observed, likewise, that more gas than the water will absorb, should be present. Heated water absorbs less ; and if water impregnated with this acid be exposed on a brisk fire, the rapid escape of the aerial bubbles affords an appearance as if the water were at the point of boiling, when the heat is not greater than the hand can bear. Congelation separates it readily and completely from water ; but no degree of cold has yet brought this acid to a state of Huidity. Carbonic acid gas is much denser than common air, and for this reason occupies the lower parts of such mines or caverns as con- tain materials which afford it by decomposi- tion. The miners call it choke-damp. The Grotto del Cano, in the kingdom of Naples, has been famous for ages on account of the effects of a stratum of fixed air which covers its bottom. It is a cave or hole in the side of a mountain, near the lake Agnano, measuring not more than eighteen feet from its entrance to the inner extremity ; where if a dog or other animal that holds down its head be thrust, it is immediately killed by inhaling this noxious fluid. Carbonic acid gas is emitted in large quan- tities by bodies in the state of the vinous fer- mentation, (see FERMENTATION); and on account of its great weight, it occupies the apparently empty space or upper part of the vessels in which the fermenting process is going on. A variety of striking experiments may be made in this stratum of elastic fluid. Lighted paper, or a candle dipped into it, is immediately extinguished ; and the smoke re- maining in the carbonic acid gas renders its sur- face visible, which may be thrown into waves by agitation like water. If a dish of water be immersed in this gas, and briskly agitated, it soon becomes impregnated, and obtains the pungent taste of Pyrmont water. In con- sequence of the weight of the carbonic acid gas, it may be lifted out in a pitcher, or bottle, which, if well corked, may be used to convey it to great distances, or it may be drawn out of a vessel by a cock like a liquid. The ef- fects produced by pouring this invisible fluid from one vessel to another, have a very sin- gular appearance : if a candle or small animal be placed in a deep vessel, the former becomes extinct, and the latter expires in a few seconds, after the carbonic acid gas is poured upon them, though the eye is incapable of distin- guishing any thing that is poured. If, how- ever, it be poured into a vessel full of air, in the sunshine, its density, being so much greater than that of the air, renders it slightly visible by the undulations and streaks it forms in this fluid, as it descends through it. Carbonic acid reddens infusion of litmus ; but the redness vanishes by exposure to the air, as the acid flies off. It has a peculiar sharp taste, which may be perceived over vats in which wine or beer is fermenting, as also in sparkling Champaign, and the brisker kinds of cider. Light passing through it is refracted by it, but does not effect any sensible alteration in it, though it appears, from experiment, that it favours the separation of its principles by other substances. It will not unite with an overdose of oxygen, of which it contains 72.72 parts in 100, the other 27-28 being pure carbon. It not only destroys life, but the heart and muscles of animals killed by it lose all their irritability, so as to be insensible to the stimulus of galvanism. Carbonic acid is dilated by heat, but not otherwise altered by it. It is not acted upon by oxygen. Charcoal absorbs it, but gives it out again unchanged, at ordinary temper- atures ; but when this gaseous acid is made to traverse charcoal ignited in a tube, it is converted into carbonic oxide. Phosphorus is insoluble in carbonic acid gas j but is capable ACI ACI of decomposing it by compound affinity, when assisted by sufficient heat ; and Priestley and Cruickshank have shown, that iron, zinc, and several other metals, are capable of producing the same effect. The inflammable air of marshes is frequently carburetted hydrogen intimately mixed with carbonic acid gas, and the sulphuretted hydrogen gas obtained from mineral waters is very often mixed with it. Carbonic acid appears from various experi- ments of Ingenhousz to be of considerable utility in promoting vegetation. It is pro- bably decomposed by the organs of plants, its base furnishing part at least of the carbon that is so abundant in the vegetable kingdom, and its oxygen contributing to replenish the at- mosphere with that necessary support of life, which is continually diminished by the re- spiration of animals and other causes. The most exact experiments on the neutral carbonates concur to prove, that the prime equivalent of carbonic acid is 2-75 ; and that it consists of one prime of carbon 0-75 + 2.0 oxygen. This proportion is most exactly deduced from a comparison of the specific gravities of carbonic acid gas and oxygen ; for it is well ascertained that the latter, by its combination with charcoal, and conversion into the former, does not change its volume. Now, 100 cubic inches of oxygen weigh 33.8 gr. and 100 cubic inches of carbonic acid 46.5, showing the weight of combined charcoal in that quan- tity to be 12.7. But the oxide of carbon con- tains only half the quantity of oxygen which carbonic acid does ; and we hence infer, that the oxide of carbon consists of one prime of oxygen united to one of carbon. This a priori judgment is confirmed by the weight 2.75 de- duced from the carbonates, as the prime equi- valent of carbonic acid. Therefore we have this proportion : If 33.8 represent two primes of oxygen or 2; 12.7 will represent one of carbon; 33.8: 2: : 12.7: 0.751, being, as above, the prime equivalent or first combining proportion of carbon. If the specific gravity of atmospheric air be called 1.0000, that of carbonic acid will be 1.5277. We have seen that water absorbs about its volume of this acid gas, and thereby acquires a specific gravity of 1.0015. On freezing it, the gas is as completely expelled as by boiling. By artificial pressure with forcing pumps, water may be made to absorb two or three times its bulk of carbonic acid. When there is also added a little potash or soda, it be- comes aerated or carbonated alkaline water, a pleasant beverage, and a not inactive remedy in several complaints, particularly dyspepsia, hiccup, and disorders of the kidneys. Alcohol condenses twice its volume of carbonic acid. The most beautiful analytical experiment with carbonic acid is the combustion of potassium in it, the formation of potash, and the depo- sition of charcoal. Nothing shows the power of chemical research in a more favourable light than the extraction of an invisible gas from Parian marble or crystallized spar, and its resolution by such an experiment into oxygen and carbon. From the proportions above stated, 5 gr. of potassium should be used for 3 cubic inches of gas. If less be employed, the whole gas will not be decom- posed, but a part will be absorbed by the pot- ash. From the above quantities, 3-8ths of a grain of charcoal will be obtained. If a por- celain tube, containing a coil of fine iron wire, be ignited in a furnace, and if carbonic acid be passed backwards and forwards by means of a full and empty bladder, attached to the ends of the tube, the gas will be converted into carbonic oxide, and the iron will be oxidized. Carbonic acid gas may be rendered liquid by great pressure. Take a strong glass syphon, and seal the end of its shorter leg. By means of a long glass funnel, nearly fill that leg with strong sulphuric acid : obstruct the bended part with a bit of platinum foil, and introduce over this small pieces of carbonate of ammo- nia till the tube be nearly filled : now seal strongly by fusion the open end of the tube ; then make the sulphuric acid to run over on the carbonate, and leave the tube inclined in such a position as that all the acid may drain out of the shorter leg. Great care must mean- while be taken of the eyes, for the tube is very apt to explode. When the clean-drained end is afterwards placed in a mixture of ice and salt, carbonic acid in the liquid state will distil over. Carbonic acid is a limpid, colourless body, extremely fluid, which floats upon the other contents of the tube, so that the hazardous process of distillation is hardly necessary, though this goes on rapidly at the difference of temperature between 32 and 0. Its re- fractive power is much less than that of water. Its vapour exerts a pressure of 30 atmospheres at a temperature of 32. As this liquid acid remains in contact with concentrated sulphuric acid, it may be inferred to be free from water. For this most interesting discovery, and other analogous ones on other gases, we are indebted to Mr. Faraday. Ph. Tr. 1823. In point of affinity for the earths and alkalis, carbonic acid stands apparently low in the scale. The carbonates are characterised by effer- vescing with almost all the acids, even the acetic, when they evolve their gaseous acid, which, passed into lime water by a tube, de- prives it of its taste, and converts it into chalk and pure water. The carbonate of larytcs was, by Dr. Wi- thering, first found native at Alston Moor in Cumberland, in 1783. From this circum- stance it has been termed Witherite by Werner. It may be prepared by exposing a solution of pure barytes to the atmosphere, when it will be covered with a pellicle of this salt by ab- ACI ACI sorbing carbonic acid ; or carbonic acid may be received into this solution, in which it will immediately form a copious precipitate ; or a solution of nitrate or muriate of barytes may be precipitated by a solution of the carbonate of potash, soda, or ammonia. The precipitate, in either of these cases, being well washed, will be found to be very pure carbonate of barytes. The carbonate of barytes is soluble only in 4304 times its weight of cold water, and 2304 of boiling water, and this requires a long time ; but water saturated with carbonic acid dis- solves l-830th. It is not altered by exposure to the air, but is decomposed by the applica- tion of a very violent heat, either in a black lead crucible, or when formed into a paste with charcoal powder. Sulphuric acid, in a con- centrated state, or diluted with three or four parts of water, does not separate the carbonic acid with effervescence, unless assisted by heat. Muriatic acid does not act upon it likewise, unless diluted with water, or assisted by heat And nitric acid does not act upon it at all, un- less diluted. It has no sensible taste, yet it is extremely poisonous. As this salt has lately been found, in large quantities, near Murton in Cumberland, and some other places in the vicinity, it might probably be introduced into manufactures with advantage, as for extracting the bases of se- veral salts. It is composed of 2.75 parts of acid, and 9.75 of barytes. Its prime equivalent is there- fore the sum of these numbers = 12.5. Carbonate of strontian was first pointed out as distinct from the preceding species by Dr. Crawford, in 1790. Sec HEAVY SPAU. It consists of 6.5 strontites +2.75 carbonic acid = 9.25. Carbonate of lime exists in great abundance in nature. It has scarcely any taste ; is insolu- ble in pure water, but water saturated with car- bonic acid takes up 1-1 500th, though as the acid flies off this is precipitated. It suffers little or no alteration on exposure to the air. When heated it decrepitates, its water flies off, and lastly its acid ; but this requires a pretty strong heat. By this process it is burned into lime. It is composed of 3.5 lime + 2.75 carbonic acid = 6.25 ; or in 100 parts, of 56. lime and 44. acid. See CALCAREOUS SPAR and LIME- STOXE. The carbonate or sub-carbonate of potash was long known by the name of vegetable alkali. As water at the usual temperature of the air dissolves rather more than its weight of this salt, we have thus a ready mode of detecting its adulterations in general ; and as it is often of consequence in manufactures, to know how much alkali a particular specimen contains, this may be ascertained by the quantity of sul- phuric acid it will saturate. This salt is deliquescent. It consists of 6 potash -f 2-75 carbonic acid = 8.75. The U-carlonate of potash crystallizes, ac- cording to Fourcroy, in square prisms, the apices of which are quadrangular pyramids. According to Pelletier they are tetraedral rhoTn- boidal prisms, with diedral summits. The complete crystal has eight faces, two hexagons, two rectangles, and four rhombs. It has an urinous but not caustic taste, changes the sy- rup of violets green : boiling water dissolves five-sixths of its weight, and cold water one- fourth ; alcohol, even when hot, will not dis- solve more than l-1200th. Its specific gravity is 2.012. When it is very pure and well crystallized it effloresces on exposure to a dry atmosphere, though it was formerly considered as deliques- cent. It was thought that the common salt of tartar of the shops was a compound of this car- bonate and pure potash ; the latter of which, being very deliquescent, attracts the moisture of the air till the whole is dissolved. From its smooth feel, and the manner in which it was prepared, the old chemists called that solution oil of tartar per deliquium. The bi- carbonate of potash melts with a gentle heat, loses its water of crystallization, amounting to T ^, and gives out one-half of its carbonic acid. To obtain the bi carbonate we must saturate the common carbonate with car- bonic acid, which is best done by passing the acid in the state of gas through a solution of the salt in twice its weight of water. The bi-carbonate, usually called super-car- bonate by the apothecaries, consists of 2 primes of carbonic acid = 5.500, 1 of potash = 6, and one of water = 1.125, in all 12.625. The carbonate of soda has likewise been long known, and distinguished from the pre- ceding by the name of mineral alkali. In com- merce it is usually called barilla, or soda ; in which state, however, it always contains a mixture of earthy bodies, and usually common salt. It may be purified by dissolving it in a small portion of water, filtering the solution, evaporating at a low heat, and skimming oft the crystals of muriate of soda as they form on its surface. When these cease to form, the so- lution may be suffered to cool, and the car- bonate of soda will crystallize. It is found abundantly in nature. In Egypt, where it is collected from the surface of the earth, particularly after the desiccation of tem- porary lakes, it has been known from time im- memorial by the name of nitrum^ natron, or natrum. A carbonate of soda exported from Tripoli, which is called Trona from the name of the place where it is found, and analyzed by Klaproth, contained of soda 37 parts, carbonic acid 38, water of crystallization 22.5, sulphate of soda 2. This does not effloresce. It crystallizes in irregular or rhomboidal de- caedrons, formed by two quadrangular pyra- mids, truncated very near their bases. Fre- quently it exhibits only rhomboidal lamina?. Its specific gravity is 1.3591. Its taste is ACI ACI urinous, and slightly acrid, without being caustic. It changes blue vegetable colours to a green. It is soluble in less than its weight of boiling water, and twice its weight of cold. It is one of the most efflorescent salts known, falling completely to powder in no long time. On the application of heat it is soon rendered fluid from the great quantity of its water of crystallization ; but is dried by a continuance of the heat, and then melts. It is somewhat more fusible than the carbonate of potash, pro- motes the fusion of earths in a greater degreej and forms a glass of better quality. Like that, it is very tenacious of a certain portion of its carbonic acid. It consists in its dry state of 4 soda, + 2.75 acid, = 6.75. But the crystals contain 10 prime pro- portions of water. They are composed of 22 soda, + 15.3 carbonic acid, -{- 62-7 water in 100 parts, or of 1 prime of soda = 4,1 of carb. acid =2.75, and 10 of water == 11.25, in whole 18. The bi-carbonate of soda may be prepared by saturating the solution of the preceding salt with carbonic acid gas, and then evaporating with a very gentle heat to dryness, when a white irregular saline mass is obtained. The salt is not crystallizable. Its constituents are 4 soda, +5.50 carb. acid, +1 .125 water, = 10.625 ; or in 100 parts 37-4 soda, + 52 acid, -f- 10.6 water. The intermediate native com- pound, the African trona, consists, according to Mr. R. Phillips, of 3 primes carbonic acid, + 2 soda, -f4 water; or in 100 parts, 38 soda, -f 40 acid, -f 22 water. See the article CARBONATE. The carbonate of magnesia, in a state of im- perfect saturation with the acid, has been used in medicine for some time under the simple name of magnesia. It is prepared by pre- cipitation from the sulphate of magnesia by means of carbonate of potash. Two parts of sulphate of magnesia and one of carbonate of potash, each dissolved in its own weight of boiling water, are filtered and mixed together hot; the sulphate of potash is separated by copious washing with water ; and the carbon- ate of magnesia is then left to drain, and after- wards spread thin on paper, and carried to the drying stove. When once dried it will be in friable white cakes, or a fine powder. Another mode of preparing it in the great will be found under the article MAGNESIA. The pulverulent carbonate of magnesia of the apothecary has a somewhat uncertain com- position as to the proportion of acid, earth, and water. But there exists in nature a car- bonated magnesia in the true equivalent pro- portions of 2.75 acid to 2.5 base. See MAG-' NESITE and DOLOMITE. Carbonate of ammonia, when very pure, is in a crystalline form, but seldom very regular. Its crystals are so small, that it is difficult to determine their figure. The crystals commonly produced by sublimation are little bundles of needles, or very slender prisms, so arranged as to represent herborizations, fern leaves, or feathers. The taste and smell of this salt are the same with those of pure ammonia, but much Weaker. It turns the colour of violets green, and that of turmeric brown. It is soluble in rather more than thrice its weight of cold water, and in its own weight of hot water ; but a boiling heat volatilizes it. When pure, and thoroughly saturated, it is not perceptibly alter- able in the air ; but when it has an excess of ammonia, it softens and grows moist. It can- not be doubted, however, that it is soluble in air ; for if left in an open vessel, it gradually diminishes in weight, and its peculiar smell is diffused to a certain distance. Heat readily sublimes, but does not decompose it. It has been prepared by the destructive dis- tillation of animal substances, and some others, in large iron pots, with a fire increased by de- grees to a strong red heat, the aqueous liquor that first comes over being removed, that the salt might not be dissolved in it Thus we had the salt of hartshorn- Thus, however, it was much contaminated by a fetid animal oil, from which it required to be subsequently purified, and is much better fabricated by mixing one part of muriate of ammonia and two of car- bonate of lime, both as dry as possible, and subliming in an earthen retort. Sir H. Davy has shown that its component parts vary, according to die manner of pre- paring it. The lower the temperature at which it is formed, the greater the proportion of acid and water. Thus, if formed at the tempera- ture of 300, it contains more than fifty per cent, of alkali ; if at 60, not more than twenty per cent. There are indeed two or three definite com- pounds of carbonic acid and ammonia. The 1st is the solid sub-carbonate of the shops. It consists of 55 carbonic acid, 30 ammonia, and 15 water; or probably of 3 primes carbonic acid, 2 ammonia, and 2 water; in all 14.75 for its equivalent. 2d, M. Gay Lussac has shown, that when 100 volumes of ammoniacal gas are mixed with 50 of carbonic acid, the two gases precipitate in a solid salt, which must consist by weight of 56 acid + 43f alkali, being in the ratio of a prime equivalent of each. 3d, When the pungent sub-carbonate is exposed in powder to the air, it becomes scentless by the evaporation of a definite por- tion of its ammonia. It is then a compound of about 55 or 56 carbonic acid, 21.5 ammo- nia, and 22.5 water. It may be represented by 2 primes of acid, 1 of ammonia, and 2 of water, 9-875. Another compound, it has been supposed, may be prepared by passing carbonic acid through a solution of the sub- carbonate till it be saturated. This, however, may be supposed to yield the same product as the last salt. M. G. Lussac infers the neutral carbonate to consist of equal volumes of the two gases, though they will not directly com- ACI ACI bine in these proportions. This would give 18.1 to 46.5 ; the very proportions in the scent- less salt. For 46.5 : 18.1 : : 55 : 21-42. The first is well known as a stimulant usually put into smelling-bottles, frequently with the addition of some odoriferous oil. The carbonate ofglucine has been examined by Vauquelin, and is, among the salts of that earth, that of which he has most accurately ascertained the properties. It is in a white, dull, clotty powder, never dry, but greasy, and soft to the feel. It is not sweet like the other salts of glucine, but insipid. It is very light, insoluble in water, perfectly unalterable by the air, but very readily decomposed by fire. Vauquelin has found, that carbonate of zircone may be formed by evaporating mu- riate of zircone, redissolving it in water, and precipitating by the alkaline carbonate. He also adds, that it very readily combines so as to form a triple salt, with either of the three alkaline carbonates. See SALT. ACID (CASEIC). The name given by Proust to an acid found in cheeses, to which he ascribes their flavour. ACID (CETIC). The name given by M. Chevreul to a supposed peculiar principle of spermaceti, which he has lately found to be the substance he has called Margarine combined with a fatty matter. ACID (CEVADIC). By the action of potash on the fat matter of the cevadilla*, there is obtained, in the same way as the delphinic, the cevadic acid ; only as this is solid, it must be separated from the cevadate of barytes, by heating this in a retort with phosphoric acid. MM. Pelletier and Caventou discovered it. It is in the form of needles, or crystalline con- cretions, of a fine white colour. Its odour is analogous to that of butyric acid. 20 C. of heat are sufficient to melt it. At a temperature not much higher, it sublimes in crystalline needles. It is soluble in water, alcohol, ether ; and unites to the bases, forming salts of little smell. The cevadate of ammonia gives a white precipitate with the salts of peroxide of iron. Ann. de Chim. et de Phys. xiv. ACID (CHLORIC) ; after ACID (Mu- KIATIC). ACID (CHLORIODIC). See ACID (HYDRIODIC). ACID (CHLOROCARBONIC). See CHLORINE, and CHLOROCARBONOUS ACID. ACID(CHLOROCYANIC). See ACID (Pnussic). * Cevadilla, petite orge (hordeolum), a plant, according to Haller, belonging to the class of delphinium and aconite. It comes from Senegal. There is another called Ceva- lilla Americana, which is corrosive. ACID (CHOLESTERIC). When we, treat with nitric acid the fat matter of the human biliary calculi, which M. Chevreul proposed to call Cholesterine, there is formed, according to MM. Pelletier and Caventou, a peculiar acid, which they call the Cholesteric. To obtain it, they cause the cholesterine to be heated with its weight of concentrated nitric acid, by which it is speedily attacked and dis- solved. . There is disengaged at the same time much oxide of azote ; and the liquor, on cool- ing, and especially on the addition of water, lets fall a yellow matter, which is the cho- lesteric acid impure, or impregnated with nitric acid. It may be purified by repeated washings in boiling water. However, after having washed it, it is better to effect its fusion in the midst of hot water ; to add to it a small quantity of carbonate of lead ; to let the whole boil for some hours, decanting and renewing the water from time to time ; then to put the remaining dried mass in contact with alcohol, and to evaporate the alcoholic solution. The residuum now obtained is the purest possible cholesteric acid. This acid has an orange-yellow colour when it is in mass ; but it appears in white needles, (whose form it is difficult to determine), when we dissolve it in alcohol, and leave it to spon. taneous evaporation. Its taste is very feeble, and slightly styptic ; its taste resembles that of butter; and its specific gravity is inter- mediate between that of alcohol and water. It fuses at 58 C. and is not decomposed till the temperature be raised much above that of boiling water. It then affords oil, water, car- bonic acid, and carburetted hydrogen, but no trace of ammonia. It is very soluble in alco- hol, sulphuric and acetic ether, in the volatile oils of lavender, rosemary, turpentine, berga- mot, &c. It is, on the other hand, insoluble in the fixed oils of olives, sweet almonds, and castor oil. It is equally so in the vegetable acids, and almost entirely insoluble in water, which takes up merely enough to make it redden litmus. Both in the cold, and with heat, nitric acid dissolves without altering it. Concentrated sulphuric acid acting on it for considerable time, only carbonizes it. It appears that the cholesteric acid is capable of uniting with the greater part of the salifiable bases. All the resulting salts are coloured, some yellow, others orange, and others red. The cholesterates of potash, soda, ammonia, and probably of morphia, are very soluble and deliquescent; almost all the others are inso- luble, or nearly so. There is none of them which cannot be decomposed by all the mineral acids, except the carbonic, and by the greater part of the vegetable acids ; so that on pouring one of these acids into a solution of the cho- lesterate, the cholesteric acid is instantly se- parated in flocks. The soluble cholesterates form precipitates in all the metallic solutions, ACI ACI whose base has the property of forming an in. soluble or slightly soluble salt with cholesteric acid. MM. Pelletier and Caventou found the cho- lesterate of barytes to consist of 100 of acid, and 56.259 base ; whence the prime equivalent of the former appears to be about 17-35. Yet they observed, on the other hand, that on treating the cholesterate of lead with sulphuric acid, they obtained as much sulphate of lead as of cholesterate. From this experiment, the equivalent of the dry acid would seem to be 5 ; hence we may imagine, that when the cholesteric acid unites to the oxide of lead, and in general to all the oxides which have a slight affinity for oxygen, there takes place something similar to what happens in the re- action of oxide of lead and oxalic acid. Jowrn. de Pharm. iii. 292. ACID (CHROMIC). This acid was at first extracted from the red lead ore of Siberia, by treating this ore with carbonate of potash, and separating the alkali by means of a more powerful acid. In this state it is impure, forming a red or orange -coloured powder, of a peculiar rough metallic taste. If this powder be exposed to the action of light and heat, it loses its acidity, and is converted into green oxide of chrome, giving out pure oxygen gas. To obtain pure chromic acid, we must distil fluor spar, chromate of lead (the yellow pig- ment), and sulphuric acid (anhydrous ?) in a leaden retort, when a gaseous mixture of chromic and fluoric acids is evolved, that is readily absorbable by water. This mixed gas affords a thick orange smoke, and on coming in contact with air deposits small red crystals of chromic acid. Ammoniacal gas introduced into this gas, contained in glass jars lined with resin, burns with explosion. Crystals of chro- mic acid are also decomposed in ammoniacal gas with a flash of light, and become protoxide of chromium. Water, by absorbing this mixed gas, acquires an orange tint; from which, by evaporation, pure chromic acid is obtained, the fluoric being volatilized. If the gas be received in a deep and moistened pla- tinum vessel, it descends, saturates the water, and is then entirely absorbed by the fluoric acid, which is at length dissipated, the vessel becoming filled with a red snow, consisting of chromic acid. This crystalline matter, when heated to redness in a platinum dish, fuses, explodes with a flash, and resolves itself into protoxide and oxygen. The crystals obtained from the water do not present this pheno- menon. The chromic acid is soluble in water, and crystallizes, by cooling and evaporation, in longish prisms of a ruby red. Its taste is acrid and styptic. Its specific gravity is not exactly known; but it always exceeds that of water. It powerfully reddens the tincture of turnsole. Its action on combustible substances is little known. If it be strongly heated with charcoal, it grows black, and passes to the metallic state without melting. Of the acids, the action of the muriatic on it is the most remarkable. If this be distilled with the chromic acid, by a gentle heat, it is readily converted into chlorine. It likewise imparts to it by mixture the property of dis- solving gold ; in which the chromic resembles the nitric acid. This is owing to the weak adhesion of its oxygen, and it is the only one of the metallic acids that possesses this pro- perty. The extraction of chromic acid from Chrome ore is performed by igniting it with its own weight of nitre in a crucible. The residue is lixiviated with water, which being then filtered, contains the chromate of potash. On pouring into this a little nitric acid and muriate of barytes, an instantaneous precipitate of the chromate of barytes takes place. After having procured a certain quantity of this salt, it must be put in its moist state into a capsule, and dissolved in the smallest possible quantity of weak nitric acid. The barytes is to be then precipitated by very dilute sulphuric acid, taking care not to add an excess of it. When the liquid is found by trial to contain neither sulphuric acid nor barytes, it must be filtered. It now consists of water, with nitric and chromic acids. The whole is to be eva- porated to dryness, conducting the heat at the end so as not to endanger the decomposition of the chromic acid, which will remain in the capsule under the form of a reddish matter. It must be kept in a glass phial well corked. Chromic acid, heated with a powerful acid, becomes chromic oxide ; while the latter, heated with the hydrate of an alkali, becomes chromic acid. As the solution of the oxide is green, and that of the acid yellow, these transmutations become very remarkable to the eye. From Berzelius's experiments on the combinations of the chromic acid with barytes, and oxide of lead, its prime equivalent seems to be 6.5 j consisting of 3.5 chromium, and 3.0 oxygen. See CHROMIUM. It readily unites with alkalis, and is the only acid that has the property of colouring its salts, whence the name of chromic has been given it. Chromate of potash is obtained from the ferriferous chrome ore, by igniting it with nitre, as described above. By careful eva- poration it may be obtained in crystals, the usual form of which is four-sided prisms ter- minated by dihedral summits, or oblique four- sided prisms, terminated by four-sided pyra- mids. Their colour is bright yellow. Their taste is cooling and disagreeable. Water at 60 dissolves about half its weight of this salt, and boiling water much more. It is insoluble in alcohol. Its specific gravity is 2.G. Heat ACI ACI causes the salt to assume a transient red tint, which passes into yellow on cooling. It con- tains no water of crystallization. Its consti- tuents are chromic acid 6.5, potash 6 = 12.5. Bichromate of potash is easily formed, by adding to a saturated solution of the yellow chromate some dilute nitric acid. On heating the mixture, the orange precipitate, which ensues on the addition of the nitric acid, is dissolved, and by slow cooling, fine crystals of bichromate may be obtained. Their form is that of square tables with bevelled edges, or flat four-sided prisms. They are permanent in the air. Their taste is metallic and bitter. Water at 60 dissolves about one- tenth of this salt ; but boiling water dissolves nearly half its weight It is not soluble in alcohol. Its sp. gr. is 1.98. It is anhydrous. It consists of chromic acid 13, potash 6 19. The chromate of barytes is very little so- luble. If the chromic acid be mixed with filings of tin and the muriatic acid, it becomes at first yellowish brown, and afterwards assumes a bluish-green colour, which preserves the same shade after desiccation. Ether alone gives it the same dark colour. With a solution of nitrate of mercury, it gives a precipitate of a dark cinnabar colour. With a solution of nitrate of silver it gives a precipitate, which, the moment it is formed, appears of a beau- tiful carmine colour, but becomes purple by exposure to the light. With nitrate of copper it gives a chesnut- red precipitate. With the solution of sul- phate of zinc, muriate of bismuth, muriate of antimony, nitrate of nickel, and muriate of platina, it produces yellowish precipitates, when the solutions do not contain an excess of acid. With muriate of gold it produces a greenish precipitate. When melted with borax, or glass, or acid of phosphorus, it communicates to it a beau- tiful emerald-green colour. If paper be impregnated with it, and ex- posed to the sun a few days, it acquires a green colour, which remains permanent in the dark. A slip of iron, or tin, put into its solution, imparts to it the same colour. The aqueous solution of tannin produces a flocculent precipitate of a brown fawn colour. See SALT. ACID (CITRIC). To procure this acid, boiling lemon-juice is to be saturated with powdered chalk, the weight of which is to be noted, and the powder must be stirred up from the bottom, or the vessel shaken from time to time. The neutral saline compound falls to the bottom, while the mucilage remains suspended in the wa- tery fluid, which must be decanted off; the remaining precipitate must then be washed with warm water until it comes off clear. To the powder thus edulcorated, a quantity of sulphuric acid, equal the chalk in weight, and diluted with ten parts of water, must be added, and the mixture boiled a few minutes. Th sulphuric acid combines with the earth, and forms sulphate of lime, which remains when the cold liquor is filtered, while the disengaged acid of lemons remains dissolved in the fluid. This last must be evaporated to the consist- ence of a thin syrup, which yields the pure citric acid in little needle-like crystals. It h necessary that the sulphuric acid should be rather in excess, because the presence of a small quantity of lime will prevent the crys- tallization. To have it perfectly pure, it must be re- peatedly crystallized, and thus it forms very large and accurately defined crystals in rhom- boidal prisms, the sides of which are inclined in angles of 60 and 120, terminated at each end by tetraedral summits, which intercept the solid angles. Its taste is extremely sharp, so as to appear caustic. It is among the vegetable acids the one which most powerfully resists decom- position by fire. In a dry and warm air it seems to efflo- resce; but it absorbs moisture when the air is damp, and at length loses its crystalline form. A hundred parts of this acid are so- luble in seventy-five of water at 60, according to Vauquelin. Though it is less alterable than most other solutions of vegetable acids, it will undergo decomposition when long kept. The crystals of citric acid, according to Ber- zelius, contain 79 per cent, of real acid. The rest is water. The same chemist found, from citrate of lead that the prime equivalent of the crystals was 9.5, while that of the real acid was 7'368 ; and its constituents were oxygen 54.831, carbon 41.369, hydrogen 3.800. My own experiments on citric acid led me to con- clude that its prime equivalent in the crystal- line state was 8.375 ; and that it consisted of oxygen 59.7, carbon 35.8, and hydrogen 4.5. Two atoms of oxygen and two of hydrogen separate when citric acid is combined with oxide of lead in what is called the dry citrate of this metal. The prime equivalent of the acid in this state becomes 6.125. Vauquelin found that 36 parts of crystallized citric acid took for saturation 6 1 of bicarbonate of potash. Hence, the prime equivalent of such acid is 7-45 ; between which, and the number given by Berzelius, mine is nearly the mean. Vau- quelin 's result differs widely from the atomic weight adopted by the Swedish chemist. If a solution of barytes be added gradually to a solution of citric acid, a flocculent preci- pitate is formed, soluble by agitation, till the whole of the acid is saturated. This salt at first falls down in powder, and then collects in silky tufts, and a kind of very beautiful and shining silvery bushes. It requires a large quantity of water to dissolve it. ACI ACI The citrate of lime has been mentioned already, in treating of the mode of purifying the acid. The citrate of potash is very soluble and de- liquescent. The citrate of soda has a dull saline taste ; dissolves in less than twice its weight of water ; crystallizes in six-sided prisms with flat summits ; effloresces slightly, but does not fall to powder; boils up, swells, and is re- duced to a coal on the fire. Citrate of ammonia is very soluble; does not crystallize unless its solution be greatly concentrated ; and forms elongated prisms. Citrate of magnesia does not crystallize. The affinities of the citric acid are arranged by Vauquelin in the following order : barytes, lime, potash, soda, strontian, magnesia, am- monia, alumina. The citric acid is found in many fruits united with the malic acid ; which see, for the process of separating them in this case. Citric acid being more costly than tartaric, may be occasionally adulterated with it. This fraud is discovered, by adding slowly to the acid dissolved in water a solution of car- bonate of potash, which will give a white pulverulent precipitate of tartar, if the citric be contaminated with the tartaric acid. When one part of citric acid is dissolved in 19 of water, the solution may be used as a substi- tute for lemon-juice. If before solution the crystals be triturated with a little sugar and a few drops of the oil of lemons, the resem- blance to the native juice will be complete. It is an antidote against sea scurvy ; but the admixture of mucilage and other vegetable matter in the recent fruit of the lemon, has been supposed to render it preferable to the pure acid of the chemist. See SALT. ACID (COLUMBIC). The experiments of Mr. Hatchett have proved, that a peculiar mineral from Massachusetts, deposited in the British Museum, consisted of one part of oxide of iron, and somewhat more than three parts of a white-coloured substance, possessing the properties of an acid. Its basis was me- tallic. Hence he named this Columbium, and the acid the Columbic. Dr. Wollaston, by very exact analytical comparisons, proved, that the acid of Mr. Hatchett was the oxide of the metal lately discovered in Sweden by Mr. Ekeberg, in the mineral yttrotantalite, and thence called tantalum. Dr. Wollaston's method of separating the acid from the mi- neral is peculiarly elegant. One part of tan- talite, five parts of carbonate of potash, and two parts of borax, are fused together in a platina crucible. The mass, after being soft- ened in water, is acted on by muriatic acid. The iron and manganese dissolve, while the columbic acid remains at the bottom. It is in the form of a white powder, which is in- soluble in nitric and sulphuric acids, but par- tially in muriatic. It forms with barytes an insoluble salt, of which the proportions, ac- cording to Berzelius, are 24.4 acid, and 9J5 barytes. By oxidizing a portion of the revived tantalum or columbium, Berzelius concludes the composition of the acid to be 100 metal and 5.485 oxygen. ACID (CROCONIC). When potas- sium is prepared from calcined tartar by Brunner's method, a gas is evolved which deposits a greyish-brown substance on cold bodies. This substance, with a little water, is separated into two parts ; one very soluble, yielding a brownish-yellow liquid, which spon- taneously concentrated, furnishes an acicular orange- coloured salt. This salt, purified by repeated crystallization, has been called by M. Gmelin croconate of potash, because it con- tains a yellow acid, which yields many com- binations of the same colour. Croconate of potash is neutral, inodorous, having a weak taste like that of nitre. Its primitive form is a rhomboid of 106 and 74. Croconic acid is obtained by treating this salt with absolute alcohol, to which a little sul- phuric acid has been added; sulphate of potash is formed and the CROCONIC ACID is dissolved. It crystallizes in grains or needles ; is transparent, of a fine yellow colour, inodor- ous, of a rough acid taste, and reddens litmus. M. Gmelin thinks that this acid is a hydracid like the prussic- Hydrocroconic acid consists of carbon 23.23, hydrogen 0.77, oxygen 24.81, water 13.98, which in the salt of potash are united with 37.21 of that alkali. ACID (CYANIC). See ACID (PRUS- sic). ACID (DELPHINIC). The name given by M. Chevreul to a substance which he has extracted from the oil of the dolphin. It re- sembles a volatile oil ; has a light lemon colour, and a strong aromatic odour, analo- gous to that of rancid butter. Its taste is pungent, and its vapour has a sweetened taste of ether. Its density at 14 C. is 0.941. It is slightly soluble in water, and very soluble in alcohol. The latter solution strongly red- dens litmus. 100 parts of delphinic acid neu- tralize a quantity of base which contains 9 of oxygen, whence its prime equivalent appears to be 11.11. Annales de Chim. et de Phys. vii. ACID (ELLAGIC). The deposit which forms in infusion of nut-galls left to itself is not composed solely of gallic acid and a matter which colours it. It contains besides a little gallate and sulphate of lime, and a new acid, which was pointed out for the first time by M. Chevreul in 1815, an acid on which M. Braconnot made observations in 1818, and which he proposed to call acid Magic, from the word galle reversed. Pobably this acid does not exist ready formed in nut-galls. It is insoluble ; and carrying down with it the greater part of the gallic acid, forms the yel- ACI 31 ACI lowish crystalline deposit. But boiling water removes the gallic acid from the ellagic; whence the means of separating them from one another Ann. de Chim. et de Phys. ix. 181. ACID (FLUORIC). The powder of crys- tallized fluor spar is to be put into a silver or leaden alembic, and its own weight of sul- phuric acid poured over it. Adapt to the alembic a silver or leaden tube terminating in a receiver of the same metal, surrounded by ice. On applying a moderate heat to the alembic, the fluoric acid will rise in vapours, which will condense in the receiver into an in- tensely active liquid, first procured by M. Gay Lussac ; and since examined by Sir H. Davy. It has the appearance of sulphuric acid, but is much more volatile, and sends off white fumes when exposed to air. Its specific gra- vity is only 1.0609. It must be examined with great caution, for when applied to the skin it instantly disorganises it, and produces very painful wounds. When potassium is in- troduced into it, it acts with intense energy, and produces hydrogen gas and a neutral salt ; when lime is made to act upon it, there is a violent heat excited, water is formed, and the same substance as fluor spar is produced. With water in a certain proportion, its density increases to 1.25. When it is dropped into water, a hissing noise is produced with much heat, and an acid fluid not disagreeable to the taste is formed if the water be in sufficient quantity. It instantly corrodes and dissolves glass. In order to insure the absolute purity of the acid, the first portions that come over may be set apart as possibly containing some silicated fluoric acid, if any silica was present in the spar. Considerable difference of opinion prevails concerning the prime equivalent of this acid, as it exists in its dry combinations. Sir H. Davy states, that 100 fluor spar yield 175.2 sulphate of lime ; whence we deduce the prime equivalent of fluoric acid to be 1.35, to lime 3.5, and oxygen 1.00. Berzelius, in his last series of experiments, gives from fluate of lime 1.357, for the equivalent of fluoric acid. Of all the fluates which he analyzed, that of lime was the only one which he succeeded in freeing perfectly from the last portions of si- lica ; and hence he regards the above result as quite satisfactory. In three experiments, in which he saturated carbonate of lime with pure fluoric acid, evaporated to dryness and ignited, he obtained from 100 parts of such fluate, on decomposing it by sulphuric acid, 174.9, 175, and 175.12 of ignited sulphate of lime. An- nales de Chim. et de Phys. 1824. This ac- cordance between Sir H. Davy's result with the native fluate, and that of Berzelius with the artificial, seems decisive. Berzelius observes that fluate of lime can be prepared only by saturating the recently pre- cipitated moist carbonate with pure fluoric acid. The fluate is thus obtained as granular as the carbonate, and may be washed ; whereas, if prepared by double decomposition, we obtain a jelly which does not change even by evapo- ration, and which cannot be washed. Dr. Thomson, in his elaborate work on the first principles of Chemistry, assigns 1.25 as the prime equivalent of fluoric acid. He deduced this number from the quantity of chloride of calcium, and of chloride of barium, to which a certain weight of fluate of soda was found to be equivalent in the way of double decomposition. But his fluate of soda was prepared in a very questionable manner ; by adding carbonate of soda in small quantities to a solution of carbonate of ammonia, previ- ously saturated with silicated fluoric gas; evaporating the whole to dryness ; redissolv- ing and evaporating till the fluate of soda crystallized in transparent crusts. As a fluo- silicate of ammonia exists, possibly some of this may have been formed, of which some silica might remain associated with his soda. Nor does his fluate of soda correspond in cha- racter to the description of this salt directly formed by Berzelius, by saturating carbonate of soda with pure fluoric acid. By spontaneous evaporation, fluate of soda is obtained in trans- parent cubes, or regular octahedrons ; by heat, in groups of small cubical grains. It contains no water of crystallization, and is more difficult of fusion by heat than glass. At the tempera- ture of 00 F. 100 parts of water dissolve only 4.8 parts of it; and at the boiling point only 4.3. Dr. Thomson says, that he dissolved 5.25 grains of his salt (white crusts, freed by ignition from their water of crystallization} in a little water. From the mode of preparing his primary salt, from its appearance, and from the defect in the process of double de- composition for forming pure fluate of lime, Dr. Thomson's atomic number seems entitled to little confidence. Fluoric acid may either be regarded as a compound of oxygen with an unknown base to be called fluor; or of hydrogen with an electro-negative element to be called fluorine. If fluor spar consist of lime associated with an oxygen acid, then this will contain one prime proportion of oxygen = 1, combined with one prime of fluor = 0.357- Were this latter number 0.375, to which it approaches, it would equal the weight of three atoms of hy- drogen. But if fluor spar be truly a fluoride of calcium, then, from its prime equivalent 4.857, we deduct the prime equivalent of cal- cium 2.5, and the remainder 2.357 will be the prime of fluorine, a number nearly 19 times that of hydrogen. From the remarkable property possessed by fluoric acid, of dissolving silica, it has been employed for etching on. glass, both in the gaseous state and combined with water. The glass is previously coated with white bees' wax.; ACI AC! on which the figures are traced with a sharp point. With the view of separating its hydrogen, Sir H. Davy applied the power of the great voltaic batteries of the Royal Institution to the liquid fluoric acid. " In this case, gas ap- peared to be produced from both the negative and positive surfaces ; but it was probably only the undecompounded acid rendered gase- ous, which was evolved at the positive surface ; for during the operation the fluid became very hot, and speedily diminished." "In the course of these investigations I made several attempts to detach hydrogen from the liquid fluoric acid, by the agency of oxygen and chlorine. It was not decomposed when passed through a platina tube heated red-hot with chlorine, nor by being distilled from salts con- taining abundance of oxygen, or those contain- ing abundance of chlorine." The marvellous activity of fluoric acid may he inferred from the following remarks of Sir H. Davy, from which also may be estimated in some measure the prodigious difficulty at- tending refined investigations on this extraor- dinary substance. " I undertook the experiment of electrizing pure liquid fluoric acid with considerable in- terest, as it seemed to offer the most probable method of ascertaining its real nature ; but considerable difficulties occurred in executing the process. The liquid fluoric acid imme- diately destroys glass, and all animal and vegetable substances; it acts on all bodies containing metallic oxides; and I know of no substances which are not rapidly dissolved or decomposed by it, except metals, charcoal, phosphorus, sulphur, and certain combinations of chlorine. I attempted to make tubes of sulphur, of muriates of lead, and of copper containing metallic wires, by which it might be electrized, but without success. I succeeded, however, in boring a piece of horn silver in such a manner that I was able to cement a platina wire into it by means of a spirit lamp ; and by inverting this in a tray of platina, filled with liquid fluoric acid, I contrived to submit the fluid to the agency of electricity in such a manner, that, in successive experiments, it was possible to collect any elastic fluid that might be produced. Operating in this way with a very weak voltaic power, and keeping the ap- paratus cool by a freezing mixture, I ascer- tained that the platina wire at the positive pole rapidly corroded, and became covered with a chocolate powder; gaseous matter separated at the negative pole, which I could never ob- tain in sufficient quantities to analyze with accuracy, but it inflamed like hydrogen. No other inflammable matter was produced when the acid was pure." We beg to refer the reader to the Philosophical Transactions for 1813 and 1814; or the 42d and 43d vols. of Tillcch's Magazine, where he will see philoso- phical sagacity and experimental skill in their utmost variety and vigour, struggling with the most mysterious and intractable powers of matter. The salts formed by fluoric acid and several bases have been lately examined by M. Ber- zelius with his accustomed precision. Superfluate of potash. This acid fluate is obtained by mixing with the acid a quantity of potash, insufficient to saturate it. On con- centrating the solution, a little of the re- dundant acid flies off, but the greater part remains and crystallizes with the alkali. This salt when heated fuses and leaves 74.9 per cent, of neutral fluate, while fumes of fluoric acid are volatilized. Berzelius regards the above acid salt, as composed of an atom of fluate of potash, and an atom of hydrated fluoric acid. Fluate of potash is prepared by saturating imperfectly fluoric acid with carbonate of pot- ash, evaporating and heating so as to expel the excess of acid. It has a sharp saline taste, is very alkaline, and deliquesces in the air. It crystallizes very difficultly in water, and then forms cubes or rectangular prisms, with stair- like scales, similar to common salt. Acid Jluate of soda. This salt is little soluble in cold water. By a slow spontaneous evaporation it affords rhomboidal crystals, having a sharp taste, and distinctly acid. Heat separates the fluoric acid in a concentrated state, without changing the form of the crys- tals, and 68.1 per cent, of neutral fluate remain. Berzelius considers this salt to be a compound of an atom of fluate of soda, and an atom of hydrated fluoric acid. Neutral Jluate of soda. This salt may be obtained directly from fluoric acid and car- bonate of soda, or by decomposing 100 parts of the double fluate of soda and silica, by 112 parts of dried carbonate of soda. When the salt is pure, and left to spontaneous evapora- tion, it affords transparent cubes of regular octohedrons, which often present a pearly lustre. Octohedrons are always obtained when the solution contains some carbonate of soda, but on the contrary, groups of small cubic grains when the evaporation is produced by elevation of temperature. The fluates of potash and soda are isomorphous with the muriates of the same bases. Fluate of soda melts with more difficulty than glass. 100 parts of water at 60 F. dissolve 4.8 of it; and at the boiling point only 4.3. Acid Jluate of ammonia, forms small gra- nular crystals, which deliquesce. Neutral Jluate of ammonia, is more volatile than sal ammoniac. It is easily obtained by heating one part of dry sal ammoniac with a little more than two parts of fluate of soda in a crucible of platinum with its lid turned up- wards. Into this lid a little cold water is put, while the bottom of the crucible is heated with a spirit of wine lamp. The fluate of ammonia thus sublimes perfectly pure in a mass of small ACI ACI prismatic crystals. It fuses before subliming, and acts on glass even in its dry state, and at ordinary temperatures. The earthy fluates are best prepared by digesting their recently precipitated moist car- bonates in an excess of fluoric acid. That of barytes is slightly soluble in water, and rea- dily in muriatic acid. ACID (FLUO-SILICIC). If instead of being distilled in metallic vessels, the mixture of fluor spar and oil of vitriol be distilled in glass vessels, little of the corrosive liquid will be obtained ; but the glass will be acted upon, and a peculiar gaseous substance will be pro- duced, which must be collected over mercury. The best mode of procuring this gaseous body is to mix the fluor spar with pounded glass or quartz ; and in this case, the glass retort may be preserved from corrosion, and the gas ob- tained in greater quantities. This gas, which is called silicated fluoric gas, is possessed of very extraordinary properties. It is very heavy; 100 cubic inches of it weigh 110.77 gr. and hence its sp. gr. is to that of air, as 3.632 is to 1.000. It is about 48 times denser than hydrogen. When brought into contact with water, it instantly deposits a white gelatinous substance, which is hydrate of silica ; it produces white fumes when suffered to pass into the atmosphere. It is not affected by any of the common com- bustible bodies; but when potassium is strongly heated in it, it takes fire and burns with a deep red light ; the gas is absorbed, and a fawn-coloured substance is formed, which yields alkali to water with slight effervescence, and contains a combustible body. The wash- ings afford potash, and a salt, from which the strong acid fluid previously described, may be separated by sulphuric acid. The gas formed by the action of liquid sulphuric acid on a mixture containing silica and fluor spar, the silicated fluoric gas or fluo- silicic acid, may be regarded as a compound of fluoric acid and silica. It affords, when decomposed by solution of ammonia, 61.4 per cent, of silica ; and hence was at first sup- posed by Sir H. Davy to consist of two prime proportions of acid i= 2.652, and one of silica = 4.066, the sum of which numbers might represent its equivalent = 6.718. One volume of it condenses two volumes of ammonia, and they form together a peculiar saline substance which is decomposed by water. The com- position of this salt is easily reconciled to the numbers given as representing silica and fluoric acid, on the supposition that it contains one prime of ammonia to one of the fluosilicic gas; for 200 cubic inches of ammonia weigh 36.2 gr. and 100 of the acid gas 1 10.77. Now " 36.2 : 2.125 : : 110-77 : 652.125. Dr. John Davy obtained, by exposing that gas to the action of watb, -^^ of its weight of silica; and from the action of water of ammonia he separated -^L of its weight. Hence 100 cubic inches consist by weight of 68 silica and 42 of unknown fluoric matter, the gas which holds the silica in solution. Sir H. Davy, however, latterly, conceives that this gas is a compound of the bases of silica, or silicon, with fluorine, the supposed basis of fluoric acid. , Berzelius, in his late elaborate researches on the fluoric combinations (Annales de CJtim. et de Phys. 27- p. 289) says that the silicated fluoric acid should be regarded as nothing else than fluate of silica, for it is only with the neutral fluates that it can unite without suf- fering decomposition ; and that when a portion of silica has been separated from it, it can be replaced only by an alkali, an oxide, or water. When he put silicated fluoric gas in contact with carbonate of potash or soda, reduced to a very fine powder, there was no more of it ab- sorbed than what might be ascribed to mois- ture contained in the carbonate, and the salt, after exposure to the gas for several days, had absorbed but an extremely small portion of it. The same result is observed with pure lime and the bicarbonate of potash. But the gas is very easily absorbed when exposed, even without moisture, to a finely pulverized fluate, either -with an alkaline, earthy, or metallic base. At the end of a few hours, the fluate is com- pletely saturated with the gas ; showing that the portion of fluoric acid and silica absorbed, has no need of any new base for its saturation. This simple fact shows that the pretended fluo- silicates, instead of being combinations of a fluate with a silicate, are rather combinations of fluate of silica with fluates of the other bases. M. Berzelius infers from his experiments that fluate of silica is formed of 100 parts fluoric acid and 144.5 silica. Water separates one third of this silica. ACID (FLUO-BORIC). If, instead of glass or silica, the fluor spar be mixed with dry vitreous boracic acid, and distilled in a glass vessel with sulphuric acid, the proportions be- ing one part boraCic acid, two fluor spar, and twelve oil of vitriol, the gaseous substance formed is of a different kind, and is called the fluoboric gas. 100 cubic inches of it weigh 73.5 gr. according to Sir H. Davy, which makes its density be to that of air as 2.41 is to 1.00 ; but Dr. John Davy states its density to that of air as 2.371 to 1.000. It is colourless; its smell is pungent, and resembles that of mu- riatic acid ; it cannot be breathed without suf- focation ; it extinguishes combustion ; and red- dens strongly the tincture of turnsole. It ha* no manner of action on glass, but a very pow- erful one on vegetable and animal matter : it attacks them with as much force as concen- trated sulphuric acid, and appears to operate on these bodies by the production of water ; for while it carbonizes them, or evolves carbon, they may be touched without any risk of burn- ing. Exposed to a high temperature, it is not decomposed ; it is condensed by cold without D ACI ACI changing its form. When it is put in contact with oxygen, or air, either at a high or low temperature, it experiences no change, except seizing, at ordinary temperatures, the moisture which these gases contain. It becomes in con- sequence a liquid which emits extremely dense vapours. It operates in the same way with all the gases which contain hygrometric water. However little they may contain, it occasions in them very perceptible vapours. It may hence be employed with advantage to show whether or not a gas contains moisture. No combustible body, simple or compound, attacks fluoboric gas, if we except the alkaline metals. Potassium and sodium, with the aid of heat, burn in this gas, almost as brilliantly as in oxygen. Boron and fluate of potash are the products of this decomposition. It might hence be inferred, that the metal seizes the oxygen of the boracic acid, sets the boron at liberty, and is itself oxidized and combined with the fluoric acid. According to Sir H. Davy's views, the fluoboric gas being a com- pound of fluorine and boron, the potassium unites to the former, giving rise to the fluoride of potassium, while the boron remains disen- Fluoboric gas is very soluble in water. Dr. John Davy says, water can combine with 700 times its own volume, or twice its weight at the ordinary temperature and pressure of the air. The liquid has a specific gravity of 1 .770. If a bottle containing this gas be uncorked un- der water, the liquid will rush in and fill it with explosive violence. Water saturated with this gas is limpid, fuming, and very caustic. By heat about one-fifth of the absorbed gas may be expelled ; but it is impossible to abstract more. It then resembles concentrated sulphuric acid, and boils at a temperature considerably above 212. It afterwards condenses altogether, in striae, although it contains still a very large quantity of gas. It unites with the bases, forming salts, called fluoborates, none of which has been applied to any use. The most im- portant will be stated under the article SALT. The 2d part of the Phil. Transactions for 1812, contains an excellent paper by Dr. John Davy on fluosilicic and fluoboric gases, and the combinations of the latter with ammoniacal gas. When united in equal volumes, a pul- verulent salt is formed ; a second volume of ammonia, however, gives a liquid compound ; and a third of ammonia, which is the limit of combination, affords still a liquid; both of them curious on many accounts. " They are," says he, " the first salts that have been ob- served liquid at the common temperature of the atmosphere. And they are additional facts in support of the doctrine of definite pro- portions, and of the relation of volumes." ACID (FLUO-TANTALIC). This acid is prepared in a similar way to the following ; and forms, with the bases, salts called Jtuo- tantalates. ACID (FLUO-TITANIC). When fluo- ric acid is poured on titanic acid, the latter becomes warm, even after having been previ- ously ignited, and dissolves completely with the aid of heat. Evaporated at a gentle heat to the consistence of syrup, the solution affords crystals, which do not re-dissolve completely in water, but which are decomposed into two peculiar combinations, of which one is acidu- lous and soluble, and the other with excess of base is insoluble. The solution of the former, namely of the fluo-titanic acid, in water, is analogous to the liquid fluosilicic acid ; it contains fluo-titanic acid, and fluoric acid combined with water. The water may be re- placed by other bases, and in this way may be formed a series of salts which M. Berzelius calls fluo-titanatcs. The Jtuo-tHanate of pot- ash crystallizes in brilliant scales like boracic acid, which re-dissolve in water without de- composition. It consists in 100 parts of pot- ash 38.7, titanic acid 35, and fluoric acid 26.3. ACIDS (FERROPRUSSIC and FER- RURETTED CHYAZIC). See ACID (PRUSSIC). ACID (FORMIC). To procure pure formic acid, G-hlen saturates the expressed liquor of ants with subcarbonate of potash, pours into the compound sulphated peroxide of iron, filters, evaporates to the consistence of syrup, and distils in a glass retort, with a suf- ficient quantity of sulphuric acid. The pro- duct which passes into the receiver is very sour, and without any perceptible odour of sulphur- ous acid. He then puts it in contact with car- bonate of copper, evaporates the solution, and procures fine blue crystals, which he considers as formiate of copper. From this he extracts the pure and the most concentrated acid pos- sible, by decomposing the salt with two-thirds of its weight of sulphuric acid, aided by heat, distilling it into a receiver, and rectifying by a second distillation. From 13 ounces of formi- ate thus treated, he obtained more than six ounces and a half of pure formic acid. This acid has a very sour taste, and con- tinues liquid even at very low temperatures. Its specific gravity is 1.1168 at 68, which is much denser than acetic acid ever is. Berze- lius finds, that the formiate of lead consists of 4.696 acid, and 14 oxide of lead ; and that the ultimate constituents of the dry acid are hydro- gen 2.84 -f carbon 32.40 -f oxygen 64.76 = 100. M. Dobereiner has recently succeeded (See Gilbert's Annales, xi. 1070 m forming this acid artificially. When a mixture of tartaric acid, or of cream of tartar, black oxide of man- ganese, and water, is heated, a tumultuous action ensues, carbonic acid is evolved, and a liquid acid distils over, which, on superficial examination, was mistaken for acetic acid, but which now proves to be formic acid. This acid, mixed with concentrated sulphuric acid, is at common temperatures converted into ACI 35 ACI water and carbonic oxide ; nitrate of silver or of mercury converts it, when gently heated, into carbonic acid, the oxides being at the same time reduced to the metallic state. With barytes, oxide of lead, and oxide of copper, it produces compounds, having all the properties of the genuine formiates of these metals. If a portion of sulphuric acid be employed in the above process, the tartaric acid is resolved en- tirely into carbonic acid, water, and formic acid ; and the product of the latter is much increased. The best proportions are, two parts tartaric acid, five peroxide of manganese, and five sulphuric acid diluted with about twice its weight of water. M. Dobereiner finds that when formic acid is decomposed by sulphuric acid, it is resolved into 23.3 water, and 7^-7 carbonic oxide in 100 parts; or of one volume of vapour of water, and two volumes carbonic oxide gas ; or two atoms carbon, three oxygen, and one hydrogen. ACID (FULMINIC). Put 6.5 parts of nitric acid, sp. gravity 1.36 or 1.38, into a pint matrass, and a piece of coin, containing nearly 35 parts of pure silver. Pour the resulting solution into about 927 parts of strong alkohol, and heat to ebullition. On the appearance of turbidness, remove from the fire, and add by degrees an equal quantity of alkohol to the solution, in order to moderate the ebullition, and to cool it. Filter it when cold, and wash away the whole free acid. The fulminate of silver is now pure and white as snow. Dry it in a steam heat for 2 or 3 hours, after which it will be found to equal in weight the silver em- ployed. A slight blow between hard bodies explodes it. It may be analyzed by rubbing it with the finger with 40 times its weight of peroxide of copper, and igniting the mixture tube. 100 parts of it, analyzed in this way, afforded 77.528 of oxide of silver. The acid, associated with this oxide, is the cyanic. Hence the ultimate constituents are in 100 parts: silver, 72.187; oxygen, 5.341; cyanogen, 17-16; oxygen (combined with the silver), 5,312. It consists, therefore, of 1 atom oxide of silver, 14-75 ; 2 atoms cy- anogen, 6.5 ; 2 oxygen, 2 = 23.25. To prepare alkaline fulminates, chlorides should be used. Thus to obtain the double fulminate of silver and potash, decompose the fulminate of silver by chloride of potassium ; being careful to add no more of the chloride than is sufficient to precipitate rather less than half the silver. The solution will contain the double fulminate. Liebeg Sf Gay Lussac, Annales de Chim. et Phys. xxv. 285. ACID (FUNGIC). The expressed juice of the boletus juglandis, boletus pseudoignia- rius, the phallus impudicus, merulius cantha- rellus, or the peziza nigra, being boiled to coagulate the albumen, then filtered, evapo- rated to the consistence of an extract, and acted on by pure alcohol, leaves a substance which has been called by Braconnot Fungic Acid. He dissolved that residue in water, added solution of acetate of lead, whence re- sulted fungate of fenrf, which he decomposed at a gentle heat by dilute sulphuric acid. The evolved fungic acid being saturated with ammonia, yielded a crystallized fungate of ammonia, which he purified by repeated so- lution and crystallization. From this salt by acetate of lead, and thereafter sulphuric acid as above detailed, he procured the pure fungic acid. It is a colourless, uncrystallizable, and deli- quescent mass, of a very sour taste. The fun- gates of potash and soda are uncrystallizable ; that of ammonia forms regular six-sided prisms ; that of lime is moderately soluble, and is not affected by the air ; that of barytes is soluble in 15 times its weight of water, and crystallizes with difficulty ; that of magnesia appears in soluble granular crystals. This acid precipitates from the acetate of lead a white flocculent fungate, which is soluble in distilled vinegar. When insulated, it does not affect solution of nitrate of silver; but the fungates decompose this salt. ACID (GALLIC). This acid is found in different regetable substances possessing astringent properties, but most abundantly in the excrescenses termed galls or nut-galls, whence it derives its name. It may be ob- tained by macerating galls in water, filtering, and suffering the liquor to stand exposed to the air. It will grow mouldy, be covered with a thick glutinous pellicle, abundance of glutinous flocks will fall down, and, in the course of two or three months, the sides of the vessel will appear covered with small yellow- ish crystals, abundance of which will likewise be found on the under surface of the super- natant pellicle. These crystals may be puri- fied by solution in alcohol, and evaporation to dry ness. M. Deyeux recommends to put the powder- ed galls into a glass retort, and apply heat slowly and cautiously ; when the acid will rise and be condensed in the neck of the retort. This process requires great care, as, if the heat be carried so far as to disengage the oil, the crystals will be dissolved immediately. The crystals thus obtained are pretty large, laminated, and brilliant. M. Baruel, of the School of Medicine at Paris, finds that he can obtain pure gallic acid by pouring solution of white of egg into the infusion of nut-galls, till this ceases to be disturbed; then to evaporate the clarified liquid to dryness, to heat the residuum with alcohol, to filter the new liquid, and concen- trate it to the proper degree for the formation of gallic acid. The gallic acid placed on a red-hot iron burns with flame, and emits an aromatic smell, not unlike that of benzoic acid. It is soluble in 20 parts of cold water, and in 3 parts at a boiling heat. It is more soluble in D2 ACI 36 ACI alcohol, which takes up an equal weight if heated, and one-fourth of its weight cold. It has an acido-astringent taste, and reddens tincture of litmus. It does not attract hu- midity from the air. From the gallate of lead, Berzelius infers the equivalent of this acid to be 8.00. Its ultimate constituents are, hydrogen 5.00 + carbon 56.64 + oxygen 38.36 100. This acid, in its combinations with the salifiable bases, presents some remarkable phe- nomena. If we pour its aqueous solution by slow degrees into lime, barytes, or strontites water, there will first be formed a greenish- white precipitate. As the quantity of acid is increased, the precipitate changes to a violet hue, and eventually disappears. The liquid has then acquired a reddish tint. Among the salts, those only of black oxide and red oxide of iron are decomposed by the pure gallic acid. It forms a blue precipitate with the first, and a brown with the second. But when this acid is united with tannin, it de- composes almost all the salts of the permanent metals. Concentrated sulphuric acid decomposes and carbonizes it ; and the nitric acid converts it into malic and oxalic acids. United with barytes, strontites, lime, and magnesia, it forms salts of a dull yellow colour, which are little soluble, but more so if their base be in excess. With alkalis it forms salts that are not very soluble in gene- ral. Its most distinguishing characteristic is its great affinity for metallic oxides, so as, when combined with tannin, to take them from powerful acids. The more readily the me- tallic oxides part with their oxygen, the more they are alterable by the gallic acid. To a solution of gold, it imparts a green hue ; and a brown precipitate is formed, which readily passes to the metallic state, and covers the solution with a shining golden pellicle. With nitric solution of silver, it produces a similar effect. Mercury it precipitates of an orange- yellow ; copper, brown ; bismuth, of a lemon colour; lead, white; iron, black. Platina, zinc, tin, cobalt, and manganese, are not pre- cipitated by it. On dissolving gallic acid in ammonia, and placing the solution in contact with oxygen, M. Dobereiner found that it absorbed sufficient to convert all the hydrogen of the gallic acid into water. In this way the acid is converted into ulmin, which is composed of 2 atoms carbon -f- 1 hydrogen -|- 2 oxygen. 100 parts of gallic acid absorb 38 of oxygen, within 24 hours. The solution meanwhile becomes brown coloured and opaque. The gallic acid is of extensive use in the art of dyeing, as it constitutes one of the principal ingredients in all the shades of black, and is employed to fix or improve several other colours. It is well known as an ingre- dient in ink. See GALLS, DYEING, INK, and SALT. ACID (HYDRIODIC). This acid resembles the muriatic in being gaseous in it insulated state. If four parts of iodine be mixed with one of phosphorus, in a small glass retort, applying a gentle heat, and add- ing a few drops of water from time to time, a gas comes over, which must be received in the mercurial bath. Its specific gravity is 4.4 ; 100 cubic inches, therefore, weigh 134.2 grains. It is elastic and invisible, but has a smell somewhat similar to that of muriatic acid. Mercury after some time decomposes it, seizing its iodine, and leaving its hydrogen, equal to one-half of the original bulk, at liberty. Chlorine, on the other hand, unites to its hydrogen, and precipitates the iodine. From these experiments, it evidently consists of vapour of iodine and hydrogen, which com- bine in equal volumes, without change of their primitive bulk. Its composition by weight is therefore 8.61 of iodine -f- 0.0694 hydrogen, which is the relation of their gasiform densi- ties; and if 8.61 be divided by 0.0694, it will give the prime of iodine 124 times greater than hydrogen; and as the prime of oxygen is eight times more than that of hydrogen, on dividing 124 by 8, we have 15.5 for the prime equivalent of iodine; to which, if we add 0.125, the sum 15.625 represents the equiva- lent of hydriodic acid. The number deduced for iodine, from the relation of iodine to hy- drogen in volume, approaches very nearly to 15.621, which was obtained in the other ex- periments of M. Gay Lussac. Hydriodic acid is partly decomposed at a red heat, and the decomposition is complete if it be mixed with oxygen. Water is formed, and iodine sepa- rated. M. Gay Lussac, in his admirable memoir on iodine and its combinations, published in the Ann. de Chimie, vol. xci. says, that the specific gravity he there gives for hydriodic gas, viz. 4.443, must be a little too great, for traces of moisture were seen in the inside of the bottle. In fact, if we take 15.621 as the prime of iodine to oxygen, whose specific gravity is 1.1111; and multiply one-half of this number by 15.621, as he does, we shall have a product of 8.6696, to which adding 0.0694 for the density of hydrogen, we get the sum 8-7390, one-half of which is ob- viously the density of the hydriodic gas = 4.3695. When the prime of iodine is taken at 15.5, then the density of the gas comes out 4.3. We can easily obtain an aqueous hydriodic acid very economically, by passing sulphuretted hydrogen gas through a mixture of water and iodine in a Woolfe's bottle. On heating the liquid obtained, the excess of sulphur flies off, and leaves liquid hydriodic acid. At tempe- ratures below 262, it parts with its water; and becomes of a density = 1.7. At 262 the ACI 37 ACI add distils over. When exposed to the air, it is speedily decomposed, and iodine is evolved. Concentrated sulphuric and nitric acids also decompose it. When poured into a saline solution of lead, it throws down a fine orange precipitate. With solution of peroxide of mer- cury, it gives a red precipitate ; and with that of silver, a white precipitate insoluble in am- monia. Hydriodic acid may also be formed, by passing hydrogen over iodine at an elevated temperature. The compounds of hydriodic acid with the salifiable bases may be easily formed, either by direct combination, or by acting on the basis in water, with iodine. The latter mode is most economical. Upon a determinate quan- tity of iodine, pour solution of potash or soda, till the liquid ceases to be coloured. Evapo- rate to dryness, and digest the dry salt in alcohol of the specific gravity 0.810, or 0.820. As the iodate is not soluble in this liquid, while the hydriodate is very soluble, the two salts easily separate from each other. After having washed the iodate two or three times with alcohol, dissolve it in water, and neutral- ize it with acetic acid. Evaporate to dryness, and digest the dry salt in alcohol, to remove the acetate. After two or three washings, the iodate is pure. As for the alcohol containing the hydriodate, distil it off, and then complete the neutralization of the potash, by means of a little hydriodic acid separately obtained. Sulphurous and muriatic acids, as well as sulphuretted hydrogen, produce no change on the hydriodates, at the usual temperature of the air. Chlorine, nitric acid, and concentrated sul- phuric, instantly decompose them, and separate the iodine. With solution of silver, they give a white precipitate insoluble in ammonia; with the pernitrate of mercury, a greenish-yellow pre- cipitate ; with corrosive sublimate, a precipi- tate of a fine orange-red, very soluble in an excess of hydriodate ; and with nitrate of lead, a precipitate of an orange-yellow colour. They dissolve iodine, and acquire a deep reddish- brown colour. Hydriodate of potash, or, in the dry state, iodide of potassium, yields crystals like sea- salt, which melt and sublime at a red heat. This salt is not changed by being heated in contact with air. 100 parts of water at G4, dissolve 143 of it. It consists of 15.5 iodine, and 5 potassium. Hydriodate of soda, called in the dry state iodide of sodium, may be obtained in pretty large flat rhomboidal prisms. These prisms unite together with larger ones, terminated in echellon, and striated longways, like those of sulphate of soda. This is a true hydriodate, for it contains much water of crystallization. It consists, when dry, of 15.5 iodine -f- 3 so- dium. Hydriodate of larytct crystallizes in fine prisms, similar to muriate of strontites. In its dry state it consists of 15.5 iodine -f- 8.75 barium. The hydriodates~of lime and strontites are very soluble ; and die first exceedingly deli- quescent. Hydriodate of ammonia results from the combination of equal volumes of ammoniacal and hydriodic gases ; though it is usually prepared by saturating the liquid acid with ammonia. It is nearly as volatile as sal am- moniac ; but it is more soluble and more deliquescent. It crystallizes in cubes. From this compound we may infer the prime of hydriodic acid, from the specific gravity of the hydriodic gas; or having the prime, we may determine the sp. gr. If we call 15.625 its equivalent, then we have this proportion : As a prime of ammonia, to a prime of hy- driodic acid, so is the density of ammoniacal, to that of hydriodic gas. 2. 125: 15.625:: 0.59: 4.3. This would make 100 cubic inches weigh exactly 132 grains. Hydriodate of magnesia is formed by uniting its constituents together; it is deliquescent, and crystallizes with difficulty. It is decom- posed by a strong heat. Hydriodate of zinc is easily obtained, by putting iodine into water with an excess of zinc, and favouring their action by heat. When dried it becomes an iodide. All the hydriodates have the property of dissolving abundance of iodine ; and thence they acquire a deep reddish-brown colour. They part with it on boiling, or when exposed to the air after being dried. See SALT. ACID (HYDROBROMIC). Put bro- mine and phosphorus in contact, and moisten them with a few drops of water. A gaseous matter is evolved, which may be collected over mercury, and which is hydrobromic acid. It is colourless. Taste acid. It diffuses in the air white vapours, denser than those of mu- riatic acid in the same circumstances, and which excite coughing. This gas is not de- composed by traversing an ignited tube, either alone, or mixed with oxygen. It is instantly decomposed by chlorine, which, seizing the hydrogen, produces immediately abundant ruddy vapours, and a deposit of bromine in small drops. Tin and potassium also decom- pose hydrobromic acid, and one half of its volume of hydrogen remains. This gaseous acid combines readily with water. The solu- tion is colourless when rightly prepared ; but excess of bromine gives it a deep ruddy hue. Iron, zinc, and tin dissolve in the liquid acid, with disengagement of hydrogen. Bromine has for hydrogen a weaker affinity than chlo- rine has, but a stronger than iodine. As the prime equivalent of bromine is in- ferred from the bromide of potassium to be about 9.5, that of hydrobromic acid should be 9.625, or 77 times the weight of the prime of ACI ACI hydrogen. Balard, Annales de Chim. ct Phys. xxxii. 347. ACID (IODIC). When barytes water is made to act on iodine, a soluble hydriodate, and an insoluble iodate of barytes, are formed. On the latter, well washed, pour sulphuric acid equivalent to the barytes present, diluted with twice its weight of water, and heat the mixture. The iodic acid quickly abandons a portion of its base, and combines with the water ; but though even less than the equi- valent proportion of sulphuric acid has been used, a little of it will be found mixed with the liquid acid. If we endeavour to separate this portion, by adding barytes water, the two acids precipitate together. The above economical process is that of M. Gay Lussac ; but Sir H. Davy, who is the discoverer of this acid in a solid state, invented one which yields a purer acid. Into a long glass tube, bent like the letter L inverted (rj), shut at one end, put 100 grains of chlorate of potash, and pour over it 400 grains of muriatic acid, specific gravity 1.105. Put 40 grains of iodine into a thin long-necked receiver. Into the open end of the bent tube put some muriate of lime, and then connect it with the receiver. Apply a gentle heat to the sealed end of the former. Protoxide of chlorine is evolved, which, as it comes in contact with the iodine, produces combustion, and two new compounds, a compound of iodine and oxygen, and one of iodine and chlorine. The latter is easily se- parable by heat, while the former remains in a state of purity. The iodic acid of Sir H. Davy is a white semitransparent solid. It has a strong acido- astringent taste, but no smell. Its density is considerably greater than that of sulphuric acid, in which it rapidly sinks. It melts, and is decomposed into iodine and oxygen, at a temperature of about 620. A grain of iodic acid gives out 176.1 grain measures of oxygen gas. It would appear from this, that iodic acid consists of 15.5 iodine, to 5 oxygen. This agrees with the determination of M. Gay Lussac, obtained from much greater quan- tities ; and must therefore excite admiration at the precision of result derived by Sir H. from the very minute proportions which he used. 17C.1 grain measures are equal to 0.7 of a cubic inch ; which, calling 100 cubic inches 33.88, will weigh 0-237 of a grain, leaving 0.7C3 for iodine. And 0-763 : 0.237 : : 15.5 : 5-0. Icdic acid deliquesces in the air, and is, of course, very soluble in water. It first reddens and then destroys the blues of vegetable in- fusions. It blanches other vegetable colours. By concentration of the liquid acid of Gay Lussac, it acquires the consistence of syrup. When the temperature of inspissated iodic acid is raised to about 392, it is resolved into iodine and oxygen. Here we see the influence pf water is exactly the reverse of what M. Gay Lussac assigns to it; for, instead of giving fixity like a base to the acid, it favours its decomposition. The dry acid may be raised to upwards of 600 without being decomposed. Sulphurous acid, and sulphuretted hydrogen, immediately separate iodine from it. Sulphuric and nitric acids have no action on it. With solution of silver, it gives a white precipitate, very soluble in ammonia. It combines with all the bases, and produces all the iodates which we can obtain by making the alkaline bases act upon iodine in water. It likewise forms with ammonia a salt, which fulminates when heated. Between the acid prepared by M. Gay Lussac, and that of Sir H. Davy, there is one important difference. The latter being dissolved, may, by evaporation of the water, pass not only to the inspissated syrupy state, but can be made to assume a pasty consistence; and finally, by a stronger heat, yields the solid substance unaltered. When a mixture of it, with charcoal, sulphur, resin, sugar, or the combustible metals, in a finely divided state, is heated, detonations are produced ; and its solution rapidly corrodes all the metals to which Sir H. Davy exposed it, both gold and platinum, but much more intensely the first of these metals. It appears to form combinations with all the fluid or solid acids which it does not de- compose. When sulphuric acid is dropped into a concentrated solution of it in hot water, a solid substance is precipitated, which consists of the acid and the compound : for, on evapo- rating the solution by a gentle heat, nothing rises but water. On increasing the heat in an experiment of this kind, the solid substance formed fused; and on cooling the mixture, rhomboidal crystals formed of a pale yellow colour, which were very fusible, and which did not change at the heat at which the com- pound of oxygen and iodine decomposes, but sublimed unaltered. When urged by a much stronger heat, it partially sublimed, and par- tially decomposed, affording oxygen, iodine, and sulphuric acid. With hydro- phosphoric, the compound pre- sents phenomena precisely similar, and they form together a solid, yellow, crystalline com- bination. With hydro-nitric acid, it yields white crystals in rhomboidal plates, which, at a lower heat than the preceding acid compounds, are resolved into hydro-nitric acid, oxygen, and iodine. By liquid muriatic acid, the substance is immediately decomposed, and the compound of chlorine and iodine is formed. All these acid compounds redden vegetable blues, taste sour, and dissolve gold and pla- tinum. From these curious researches Sir H. Davy infers, that M. Gay Lussac's iodic acid is a sulpho- iodic acid, and probably a definite compound. However minute the quantity of sulphuric acid made to act on the iodide of barium may be, a part of it is always ACI 39 ACI employed to form the compound acid ; and the residual fluid contains both the compound acid and a certain quantity of the original salt. In treating of hydriodic acid, we have al- ready described the method of forming the iodates, a class of salts distinguished chiefly by their property of deflagrating when heated with combustibles. See SALT. ACID (IODOUS). Equal parts of chlo- rate of potash and iodine are to be triturated together in a glass or porcelain mortar, until they form a fine pulverulent yellow mass, in which the metallic aspect of the iodine has en- tirely disappeared. This mixture is to be put into a retort, the neck being preserved clean, and a receiver is to be attached with a tube passing to the pneumatic trough. Heat is then to be applied ; and for this purpose a spirit lamp will be sufficient ; at first a few violet vapours rise, but as soon as the chlorate begins to lose oxygen, dense yellow fumes will appear, which will be condensed in the neck of the re- tort into a yellow liquid, and run in drops into the receiver ; oxygen gas will at the same time come over.* When the vapour ceases to rise, the process is finished, and the-iodous acid obtained will have the following properties. Its colour is yellow ; taste acid and astrin- gent, leaving a burning sensation on the tongue. It is of an oily consistency, and flows with dif- ficulty. It is denser than water. Its odour somewhat resembles that of enchlorine. It reddens vegetable blues, but does not destroy them. At 112 F. it volatilizes rapidly in dense fumes. It dissolves iodine, and assumes a deep colour. Sementim, Bib. Univ.xxv. 119. ACID (CHLORIODIC). The discovery of this interesting compound constitutes an- other of Sir H. Davy's contributions to the advancement of science. In a communication from Florence to the Royal Society, in March 1 814, he gives a curious detail of its preparation and properties. He formed it, by admitting chlorine in excess to known quantities of iodine, in vessels exhausted of air, and repeat- edly heating the sublimate. Operating in this way, he found that iodine absorbs less than one-third of its weight of chlorine. Chloriodic acid is a very volatile substance, and in consequence of its action upon mercury, he was not able to determine the elastic force of its vapour. In the most considerable ex- periment which he made to determine propor- tions, 20 grains caused the disappearance of 9.6 cubical inches of chlorine. These weigh 7-296 grains. And 20 : 7-296 : : 15.5 : 5.6, a number not very far from 4.5, the prime equivalent of chlorine; and in the delicate circumstances of the experiment, an approx- imation not to be disparaged. Indeed, the first result in close vessels, giving less than one-third of the weight of chlorine absorbed, comes sufficiently near 4.5, which is just a little less than one-third of 10.5, the prime equivalent of iodine. The chloriodic acid formed by the sublima- tion of iodine in a great excess of chlorine is of a bright yellow colour ; when fused it be- comes of a deep orange, and when rendered elastic, it forms a deep orange-coloured gas. It is capable of combining with much iodine when they are heated together ; its colour be- comes, in consequence, deeper, and the chlo- riodic acid and the iodine rise together in the elastic state. The solution of the chloriodic acid in water likewise dissolves large quan- tities of iodine, so that it is possible to obtain a fluid containing very different proportions of iodine and chlorine. When two bodies so similar in their cha- racters, and in the compounds they form, as iodine and chlorine, act upon substances at the same tima, it is difficult, Sir H. observes, to form a judgment of the different parts that they play in the new chemical arrangement produced. It appears most probable, that the acid property of the chloriodic compound de- pends upon the combination of the two bodies ; and its action upon solutions of the alkalis and the earths may be easily explained, when it is considered that chlorine has a greater tendency than iodine to form double compounds with the metals, and that iodine has a greater ten- dency than chlorine to form triple compounds with oxygen and the metals. A triple compound of this kind with so- dium may exist in sea water, and would be separated with the first crystals that are formed by its evaporation. Hence, it may exist in common salt. Sir H. Davy ascertained, by feeding birds with bread soaked with water, holding some of it in solution, that it is not poisonous like iodine itself. ACID (HYDROCYANIC). See ACID (PRUSSIC). ACID (HYDROSELENIC). The best process which we can employ for procuring this acid, according to M. Ber/elius, consists in treating the seleniuret of iron with the liquid muriatic acid : (Ann. de Chim. ct de Phys, ix. 243.) The acid gas evolved must be col- lected over mercury. As in this case a little of another gas, condensible neither by water nor alkaline solutions, appears, the best sub- stance for obtaining absolutely pure hydrose- lenic acid would be seleniuret of potassium. Seleniuretted hydrogen gas is colourless. It reddens litmus. Its density has not been de- termined by experiment. Its smell resembles, at first, that of sulphuretted hydrogen gas ; but the sensation soon changes, and another suc- ceeds, which is at once pungent, astringent, and painful. The eyes become almost in- stantly red and inflamed, and the sense of smelling entirely disappears. A bubble of the size of a little pea is sufficient to produce these effects. Of all the bodies derived from the inorganic kingdom, seleniuretted hydrogen is that which exercises the strongest action on the animal economy. ^jTater dissolves this ACI ACI gas ; but in what proportions is not known. This solution disturbs almost all the metallic solutions, producing black or brown preci- pitates, which assume, on rubbing with po- lished haematites, a metallic lustre. * Zinc, man- ganese, and cerium, form exceptions. They yield flesh-coloured precipitates, which appear to be hydro-seleniurets of the oxides, whilst the others, for the most part, are merely me- tallic seleniurets. ACID (HYDROXANTHIC). If a cer- tain quantity of sulphuret of carbon be poured into an alcoholic solution of one of the alkalis, a neutral liquid is obtained, in consequence of the formation of a new acid, which neutralizes the alkali. If potash has been used, the salt may be obtained either by refrigeration, eva- poration, or precipitation by sulphuric ether. It contains no carbonic acid, or sulphuretted hydrogen, but an acid which is in the same relation to sulphuret of carbon, that hydro- cyanic acid is to cyanogen. Its compounds have been called hydroxanthates. The acid may be obtained by pouring a mixture of four parts of sulphuric acid and three of water on the salt of potash, and in a few seconds adding abundance of water. The acid collects at the bottom of the water as a transparent slightly coloured oil ; it must be quickly washed with water until free from sulphuric acid. This acid reddens litmus paper powerfully. Its odour differs from that of sulphuret of carbon. Its taste is acid and astringent. It bums readily, giving out sulphurous fumes. Dr. Zelse of Copenhagen, Journal of Science, xv. 304. ACID (HYPONITROUS). See ACID (NITRIC). ACID (HYPOPHOSPHORIC). See ACID (PHOSPHORIC). ACID (HYPOPHOSPHOROUS). See ACID (PHOSPHOROUS). ACID(HYPOSULPHURIC). See ACID (SULPHURIC). ACID (HYPOSULPHUROUS). See ACID (SULPHUROUS). ACID (IGASURIC). MM. Pelletier and Caventou, in their elegant researches on the fata Sancti Ignatii, et mix vomica, having observed ihat these substances contained a new vegetable base (strychnine) in combination with an acid, sought to separate the latter, in order to determine its nature. It appeared to them to, be new, and they called it igasuric acid, frorr the Malay name by which the natives designate in the Indies the f aba Sancti Ignatii. This bean, according to these chemists, is com- posed of igasurate of strychnine, a little wax, a concrete oil, a yellow colouring matter, gum, starch, bassorine, and vegetable fibre. To extract the acid, the rasped bean must be heated in ether, in a digester, with a valve ot* safety. Thus the concrete oil, and a little igasurate of strychnine, are dissolved out. When the powder is no longer acted on by the ether, they subject it, at several times, to the action of boiling alcohol, which carries off the oil which had escaped the ether, as also wax, which is deposited on cooling, some igasurate of strychnine, and colouring matter. All the alcoholic decoctions are united, filtered, and evaporated. The brownish-yellow resi- duum is diffused in water ; magnesia is now added, and the whole is boiled together for some minutes. By this means, the igasurate is decomposed, and from this decomposition there results free strychnine, and a sub-iga- surate of magnesia, very little soluble in water. Washing with cold water removes almost com- pletely the colouring matter, and boiling al- cohol then separates the strychnine, which falls down as the liquid cools. Finally, to procure igasuric acid from the sub-igasurate of mag- nesia, which remains united to a small quan- tity of colouring matter, we must dissolve the magnesian salt in a great body of boiling dis- tilled water ; concentrate the liquor, and add to it acetate of lead, which immediately throws down the acid in the state of an igasurate of lead. This compound is then decomposed, by transmitting a current of sulphuretted hydro- gen through it, diffused in 8 or 10 times its weight of boiling water. This acid, evaporated to the consistence of syrup, and left to itself, concretes in hard and granular crystals. It is very soluble in water, and in alcohol. Its taste is acid and very styptic. It combines with the alkaline and earthy bases, forming salts soluble in water and alcohol. Its combination with barytes is very soluble, and crystallizes with difficulty, and mushroom-like. Its combination with ammonia, when perfectly neutral, does not form a precipitate with the salts of silver, mer- cury, and iron ; but it comports itself with the salts of copper in a peculiar manner, and which seems to characterize the acid of stryclmos (for the same acid is found in mix vomica, and in snake-wood, oois de couleuvre] : this effect consists in the decomposition of the salts of copper, by its ammoniacal compound. These salts pass immediately to a green colour, and gradually deposit a greenish-white salt, of very sparing solubility in water. The acid of stryclmos seems thus to resemble meconic acid; but it differs essentially from it, by its action with salts of iron, which immediately assume a very deep red colour with the meconic acid ; an effect not produced by the acid ofstrychnos. The authors, after all, do not positively affirm this acid to be new and peculiar. Ann. de Chim. et de Phys. x. 142. ACID (IODO-SULPHURIC). When we pour sulphuric acid, drop by drop, into a concentrated and hot aqueous solution of iodic acid, there immediately results a precipitate of iodo-sulphuric acid, possessed of peculiar pro- perties. Exposed gradually to the action of a gentle heat, the iodo-sulphuric acid melts, and crystallizes on cooling into rhomboids of a pale ACI 4,1 ACI yellow colour. When strongly heated, it sub- limes, and is partially decomposed ; the latter portion being converted into oxygen, iodine, and sulphuric acid. Phosphoric and nitric acids exhibit similar phenomena. These compound acids act with great energy on the metals. They dissolve gold and platinum. ACID (HYDROTHIONIC). Some of the German chemists distinguished sulphu- retted hydrogen by this name, on account of its properties resembling those of an acid. ACID (IODIC). Seep. 38. ACID (IODOUS). Seep. 39. ACID (KINIC). A peculiar acid ex- tracted by M. Vauquelin from cinchona. Let a watery extract from hot infusions of the bark in powder be made. Alcohol removes the re- sinous part of this extract, and leaves a viscid residue, of a brown colour, which has hardly any bitter taste, and which consists of kinate of lime and a mucilaginous matter. This re- sidue is dissolved in water, the liquor is filtered and left to spontaneous evaporation in a warm place. It becomes thick like syrup, and then deposits by degrees crystalline plates, some- times hexaedral, sometimes rhomboidal, some- times square, and always coloured slightly of a reddish-brown. These plates of kinate of lime must be purified by a second crystalliza- tion. They are then dissolved in 10 or 12 times their weight of water, and very dilute aqueous oxalic acid is poured into the solution, till no more precipitate is formed. By filtra- tion, the oxalate of lime is separated, and the kinic acid being concentrated by spontaneous evaporation, yields regular crystals. It is de- composed by heat. While it forms a soluble salt with lime, it does not precipitate lead or silver from their solutions. These are cha- racters sufficiently distinctive. The kinates are scarcely known ; that of lime constitutes 7 per cent, of cinchona. ACID (KRAMERIC). A peculiar sub- stance which M. Peschier, of Geneva, thought he had found in the root of the Krameria tri- andria. ACID (LACCIC) of Dr. John. This chemist made a watery extract of pow- dered stick lac, and evaporated it to dryness. He digested alcohol on this extract, and eva- porated the alcoholic extract to dryness. He then digested this mass in ether, and evapo- rated the ethereal solution ; when he obtained a syrupy mass of a light yellow colour, which was again dissolved in alcohol. .On adding water to this solution a little resin felL A pe- culiar acid united to potash and lime remains in the solution, which is obtained free, by forming with acetate of lead an insoluble lac- cate, and decomposing this with the equivalent quantity of sulphuric acid. Laccic acid crys- tallizes; it has a wine-yellow colour, a sour taste, and is soluble, as we have seen, in water, alcohol, and ether. It precipitates lead and mercury white ; but it does fcot affect lime, barytes, or silver, in their solutions. It throws down the salts of iron white. With lime, soda, and potash, it forms deliquescent salts, soluble in alcohol. ACID (LACTIC). The extract which is obtained when dried whey is digested with alcohol contains un combined lactic acid, lac- tate of potash, muriate of potash, and a proper animal matter. As the elimination of the acid affords an instructive example of che- mical research, we shall present it at some detail from the 2d volume of Berzelius's Animal Chemistry. He mixed the above alcoholic solution with another portion of alcohol, to which ^ of con- centrated sulphuric acid had been added, and continued to add fresh portions of this mixture as long as any saline precipitate was formed, and until the fluid had acquired a decidedly acid taste. Some sulphate of potash was pre- cipitated, and there remained in the alcohol, muriatic acid, lactic acid, sulphuric acid, and a minute portion of phosphoric acid, detached from some bone earth which had been held in solution. The acid liquor was filtered, and afterwards digested with carbonate of lead, which with the lactic acid affords a salt soluble in alcohol. As soon as the mixture had ac- quired a sweetish taste, the three mineral acids had fallen down in combination with the lead, and the lactic acid remained behind, imperfectly saturated by a portion of it, from which it was detached by means of sulphuretted hydrogen, and then evaporated to the consistence of a thick varnish, of a dark brown colour, and sharp acid taste, but altogether without smell. In order to free it from the animal matter which might remain combined with it, he boiled it with a mixture of a large quantity of fresh lime and water, so that the animal sub- stances were precipitated and destroyed by the lime. The lime became yellow-brown, and the solution almost colourless, while the mass emitted a smell of soap lees, which disappeared as the boiling was continued. The fluid thus obtained was filtered, and evaporated, until a great part of the superfluous lime held in so- lution was precipitated. A small portion of it was then decomposed by oxalic acid, and carbonate of silver was dissolved in the un- combined lactic acid, until it was fully sa- turated. With the assistance of the lactate of silver thus obtained, a further quantity of muriatic acid was separated from the lactate of lime, whjch was then decomposed by pure oxalic acid, free from nitric acid, taking care to leave it in such a state that neither the oxalic acid nor lime water afforded a pre- cipitate. It was then evaporated to dryness, and dissolved again in alcohol, a small portion of oxalate of lime, before retained in union with the acid, now remaining undissolved. The alcohol was evaporated until the mass was no ACI ACI longer fluid while warm ; it became a brown clear transparent acid, which was the lactic acid, free from all substances that we have hitherto had reason to think likely to con- taminate it. The lactic acid, thus purified, has a brown- yellow colour, and a sharp sour taste, which is much weakened by diluting it with water. It is without smell in the cold, but emits, when heated, a sharp sour smell, not unlike that of sublimed oxalic acid. It cannot be made to crystallize, and does not exhibit the slightest appearance of a saline substance, but dries into a thick and smooth varnish, which slowly attracts moisture from the air. It is very easily soluble in alcohol. Heated in a gold spoon over the flame of a candle, it first boils, and then its pungent acid smell becomes very manifest, but extremely distinct from that of the acetic acid ; afterwards it is charred, and has an empyreumatic, but by no means an animal smeJl. A porous charcoal is left be- hind, which does not readily burn to ashes. When distilled, it gives an empyreumatic oil, water, empyreumatic vinegar, carbonic acid, and inflammable gases. With alkalis, earths, and metallic oxides, it affords peculiar salts : and these are distinguished by being soluble in alcohol, and in general by not having the least disposition to crystallize, but drying into a mass like gum, which slowly becomes moist in the air. Lactate of potash is obtained, when the lac- tate of lime, purified as has been mentioned, is mixed with a warm solution of carbonate of potash. It forms, in drying, a gummy, light yellow-brown, transparent mass, which cannot easily be made hard. If it is mixed with con- centrated sulphuric acid, no smell of acetic acid is perceived ; but if the mixture is heated, it acquires a disagreeable pungent smell, which is observable in all animal substances mixed with the sulphuric acid. The extract which is obtained directly from milk, contains this salt ; but this affords, when mixed with sul- phuric acid, a sharp acid smell, not unlike that of the acetic acid. This, however, depends not on acetic but on muriatic acid, which in its concentrated state introduces this modification into the smell of almost all organic bodies. The pure lactate of potash is easily soluble in al- cohol ; that which contains an excess of potash, or is still contaminated with the animal matter soluble in alcohol, which is destroyed by the treatment with lime, is slowly soluble, and re- quires about 14 parts of warm alcohol for its solution. It is dissolved in boiling alcohol more abundantly than in cold, and separates from it, while it is cooling, in the form of hard drops. The lactate of soda resembles that of pot- ash, and can only be distinguished from it by analysis. Lactate of ammonia. If concentrated lactic acid is saturated with caustic ammonia in ex- cess, the mixture acquires a strong volatile smell, not unlike that of the acetate or formiate of ammonia, which, however, soon ceases. The salt which is left has sometimes a slight ten- dency to shoot into crystals. It affords a gummy mass, which in the air acquires an excess of acidity. When heated, a great part of the alkali is expelled, and a very acid salt remains, which deliquesces in the air. The lactate ofbarytes may be obtained in the same way as that of lime ; but it then con- tains an excess of the base When evaporated, it affords a gummy mass, soluble in alcohol. A portion remains undissolved, which is a sub- salt, is doughy, and has a browner colour. That which is dissolved in the alcohol affords by evaporation an almost colourless gummy mass, which hardens into a stiffbut not a brittle varnish. It does not show the least tendency to crystallize. The salt, which is less soluble in alcohol, may be further purified from the animal matter adhering to it, by adding to it more barytes, and then becomes more soluble. The lactate of lime is obtained in the man- ner above described. It affords a gummy mass, which is also divided by alcohol into two por- tions. The larger portion is soluble, and gives a shining varnish, inclining to a light yellow colour, which, when slowly dried, cracks all over, and becomes opaque. This is pure lac- tate of lime. That which is insoluble in alcohol is a powder, with excess of the base ; received on a filter, it becomes smooth in the air like gum, or like malate of lime. By boiling with more lime, and by the precipitation of the su- perfluous base upon exposure to the air, it becomes pure and soluble in alcohol. Lactate of magnesia, evaporated to the con- sistence of a thin syrup, and left in a warm place, shoots into small granular crystals. When hastily evaporated to dryness. it affords a gum- my mass. With regard to alcohol, its pro- perties resemble those of the two preceding salts. Ammoniaco-magnesian lactate is obtained by mixing the preceding salt with caustic am- monia, as long as any precipitation continues. By spontaneous evaporation this salt shoots into needle-shaped prisms, which are little coloured, and do not change in the air. Ber- zelius has once seen these crystals form in the alcoholic extract of milk boiled to dryness ; but this is by no means a common occurrence. The lactate of silver is procured by dissolving the carbonate in the lactic acid. The solution is of a light yellow, somewhat inclining to green, and has an unpleasant taste of verdigris. When evaporated in a flat vessel, it dries into a very transparent greenish-yellow varnish, which has externally an unusual splendour like that of a looking-glass. If the evaporation is conducted in a deeper vessel, and with a stronger heat, a part ot' the salt is decomposed, and remains brown from the reduction of the silver. If this salt is dissolved in water, no ACI ACI inconsiderable portion of the silver is reduced and deposited, even when the salt has been transparent ; and the concentrated solution has a fine greenish-yellow colour, which by dilution becomes yellow. If we dissolve the oxide of silver in an impure acid, the salt becomes brown, and more silver is revived during the evaporation. The lactate of the protoxide of mercury is obtained when the lactic acid is saturated with black oxidated mercury. It has a light yellow colour, which disappears by means of repeated solution and evaporation. The salt exhibits acid properties, deliquesces in the air, and is partially dissolved in alcohol, but is at the same time decomposed, and deposits carbonate of mercury, while the mixture acquires a slight smell of ether. The lactic acid dissolves also the red oxide of mercury, and gives with it a red gummy deliquescent salt. If it is left ex- posed to a warm and moist atmosphere, it deposits, after the expiration of some weeks, a light semicrys^alline powder, which he has not examined, but which probably must be acetate of mercury. The lactate of lead may be obtained in se- veral different degrees of saturation. If the lactic acid is digested with the carbonate of lead, it becomes browner than before, but can- not be fully saturated with the oxide ; and we obtain an acid salt, which does not crystallize, but dries into a syrup-like brown mass, with a sweet austere taste. When a solution of lactic acid in alcohol is digested with finely powdered litharge until the solution becomes sweet, and is then slowly evaporated to the consistence of honey, the neutral lactate of lead crystallizes in small greyish grains, which may be rinsed with alcohol, to wash off the viscid mass that ad- heres to them, and will then appear as a grey granular salt, which when dry is light and silvery. This silver-grained salt does not change in the air ; treated with sulphuretted hydrogen it af- fords pure lactic acid. If the lactic acid is digested with a greater portion of levigated li- tharge than is required for its saturation, the fluid acquires first a browner colour, and as the digestion is continued the colour becomes more and more pale, and the oxide swells into a bulky powder, of a colour somewhat lighter than before. If the fluid is evaporated, and water is then poured on the dry mass, a very small portion of it only is dissolved ; the so- lution is not coloured, and when it is exposed to the air, a pellicle of carbonate of lead is separated from it. If the dried salt of lead be boiled with water, and the solution be filtered while hot, a great part of that which had been dissolved will be precipitated while it cools, in the form of a white, or light yellow powder, which is a sub- lactate of lead. This salt is of a light flame colour ; when dried, it remains mealy, and soft to the touch, and it is de- composed by the weakest acids, while the acid salt is dissolved in water, exhibiting a sweet taste and a brown colour. When moistened with water, it undergoes this change from the operation of the carbonic acid diffused in the air. If this salt is warmed and then set on fire at one point, it burns like tinder, and leaves the lead in great measure reduced. A hundred parts of this salt, dissolved in nitric acid, and precipitated with carbonate of potash, gave exactly 100 parts of carbonate of lead ; con- sequently its component parts, determined from those of the carbonate, must be 83 of the oxide of lead, and 1 7 of the lactic acid. At the same time we cannot wholly depend on this pro- portion, and it certainly makes the quantity of lead somewhat too great. The relation of the lactic acid to lead affords one of the best me- thods of recognizing it, and Berzelius always principally employed it in extracting this acid from animal fluids; it gives the clearest di- stinction between the lactic acid and the acetic. The lactate of iron is of a red-brown colour, does not crystallize, and is not soluble in al- cohol. The lactate of zinc crystallizes. Both these metals are dissolved by the lactic acid, with an extrication of hydrogen gas. The lac- tate of copper, according to its different degrees of saturation, varies from blue to green and dark blue. It does not crystallize. It is only necessary to compare the descrip- tions of these salts with what we know of the salts which are formed with the same bases by other acids, for example, the acetic, the malic, and others, in order to be completely convinced that the lactic acid must be a peculiar acid, perfectly distinct from all others. Its prune equivalent may be called 5.8. The nanceic acid of Braconnot resembles the lactic in many respects. ACID (LITHIC). Lithate of potash is obtained by digesting human urinary calculi in caustic lixivium; and Fourcroy recommends the precipitation of the lithic acid from this so- lution by acetic acid, as a good process for ob- taining the acid pure, in small, white, shining, and almost pulverulent needles. It has the form of white shining plates, which are denser than water. Has no taste nor smelL It dissolves in about 1400 parts of boiling water. It reddens the infusion of lit- mus. When dissolved in nitric acid, and eva- porated to dryness, it leaves a pink sediment. The dry acid is not acted on nor dissolved by the alkaline carbonates, or sub-carbonates. It de- composes soap when assisted by heat ; as it does also the alkaline sulphurets and hydrosulphu- rets. No acid acts on it, except those that oc- casion its decomposition. It dissolves in hot solutions of potash and soda, and likewise in ammonia, but less readily. The lithates may be formed, either by mutually saturating the two constituents, or we may dissolve the acid in an excess of base, and we may then pre- cipitate by carbonate of ammonia. The li- thates are all tasteless, and resemble in appear- ACI ACI ance lithic acid itself. They are not altered by exposure to the atmosphere. They are very sparingly soluble in water. They are decomposed by a red heat, which destroys the acid. The lithic acid is precipitated from these salts by all the acids, except the prussic and carbonic. They are decomposed by the ni- trates, muriates, and acetates of barytes, stron- tites, lime, magnesia, and alumina. They are precipitated by all the metallic solutions, ex- cept that of gold. When lithic acid is exposed to heat, the products are carburetted hydrogen, and carbonic acid, prussic acid, carbonate of ammonia, a sublimate, consisting of ammonia combined with a peculiar acid, which has the following properties : Its colour is yellow, and it has a cooling bitter taste. It dissolves readily in water, and in alkaline solutions, from which it is not precipitated by acids. It dissolves also sparing- ly in alcohol. It is volatile, and when sublimed a second time, becomes much whiter. The watery solution reddens vegetable blues, but a very small quantity of ammonia destroys this property. It does not cause effervescence with alkaline carbonates. By evaporation it yields permanent crystals, but ill defined, from ad- hering animal matter. These redden vegetable blues. Potash, when added to these crystals, disengages ammonia. When dissolved in nitric acid, they do not leave a red stain, as happens with uric acid ; nor does their solution in water decompose the earthy salts, as happens with alkaline lithates (or urates). Neither has it any action on the salts of copper, iron, gold, platinum, tin, or mercury. With nitrates of silver, and mercury, and acetate of lead, it forms a white precipitate, soluble in an excess of nitric acid. Muriatic acid occasions no precipitate in the solution of these crystals in water. These properties show, that the acid of the sublimate is different from the uric, and from every other known acid. Dr. Austin found, that by repeated distillations lithic acid was resolved into ammonia, nitrogen, and prussic acid. See ACID (PYROLITHIC). When lithic acid is projected into a flask with chlorine, there is formed, in a little time, muriate of ammonia, oxalate of ammonia, carbonic acid, muriatic acid, and malic acid ; the same results are obtained by passing chlorine through water, holding this acid in suspension. M. Gay Lussac mixed lithic acid with 20 times its weight of oxide of copper, put the mixture into a glass tube, and covered it with a quantity of copper filings. The copper filings being first heated to a dull red, heat was applied to the mixture. The gas which came over, was composed of 0.69 carbonic acid, and 0.31 nitrogen. He conceives, that the bulk of the carbonic acid would have been exactly double that of the nitrogen, had it not been for the formation of a little carbonate of ammonia. Hence, uric acid contains two prune equivalents of carbon, and one of nitro- gen. This is the same proportion as exists in cyanogen. Probably, a prime equivalent of oxygen is present. Dr. Prout, in the eighth vol. of the Med. Chir. Trans, describes the result of an analysis of lithic acid, effected also by ignited oxide of copper, but so conducted as to determine the product of oxygen and hydrogen. Four grains of lithic acid yielded, water 1.05, carbonic acid 11.0 c. inches, nitro- gen 5.5 do. Hence, it consisted of Hydrogen 2.857 or 1 prime = 0.125 Carbon 34.286 2 - 1.500 Oxygen 22.857 1 1.000 Nitrogen 40.00 1 = 1-750 100.000 4.375 Mr. Berard has published an analysis of lithic acid since Dr. Prout, in which he also employed oxide of copper. The following are the results : Carbon 33.61 ) f 1 Carbon Oxygen 18.89 ( which ap- J 1 Oxygen Hydrogen 8.34 f proach to j 4 Hydrogen Nitrogen 39.16 ) O Nitrogen 100.00 Here we find the nitrogen and carbon nearly in the same quantity as by Dr. Prout ; but there is much more hydrogen and less oxygen. By urate of barytes, we have the prime equivalent of uric acid equal to 15.67 ; and by urate of potash it appears to be 14.0. It is needless to try to accommodate an ar- rangement of prime equivalents to these dis- crepancies. The lowest number would require, on the Daltonian plan, an association of more than twenty atoms, the grouping of which is rather a sport of fancy than an exercise of reason. For what benefit could accrue to chemical science by stating, that if we consider the atom of lithic acid to be 16.75, then it would probably consist of 7 atoms Carbon =: 5.25 31.4 3 Oxygen = 3.00 17-90 12 Hydrogen = 1.500 8.90 4 Nitrogen = 7-00 41.80 26 16.75 100.0 ACID (MALIC). The acid of apples; the same with that which is extracted from the fruit of the mountain ash. See ACID (SoiiBic). ACID (MARGARIC). When we im- merse soap made of pork-grease and potash, in a large quantity of water, one part is dis- solved, while another part is precipitated in the form of several brilliant pellets. These are separated, dried, washed in a large quan- tity of water, and then dried on a filter. They are now dissolved in boiling alcohol, sp. gr. 0.820, from which, as it cools, the pearly sub- stance falls down pure. On acting on this with dilute muriatic acid, a substance of a peculiar kind, which M. Chevreul, the dis- AGI ACI coverer, calls margarine, or margaric acid, is separated. It must be well washed with water, dissolved in boiling alcohol, from which it is recovered in the same crystalline pearly form, when the solution cools. Margaric acid is pearly white, and taste-^ less. Its smell is feeble, and a little similar to that of melted wax. Its specific gravity is inferior to water. It melts at 134 F. into a very limpid, colourless liquid, which crystal- lizes, on cooling, into brilliant needles of the finest white. It is insoluble in water, but very soluble in alcohol, sp. gr. 0.800. Cold margaric acid has no action on the colour of litmus ; but when heated so as to soften with- out melting, the blue was reddened. It com- bines with the salifiable bases, and forms neutral compounds. 100 parts of it unite to a quantity of base containing three parts of oxygen, supposing that 100 of potash contain 17 of oxygen. Two orders of margarates are formed, the margarates and the supermarga- rates, the former being converted into the latter, by pouring a large quantity of water on them. Other fats besides that of the hog yield this substance. Acid. Margarate of potash consists of 100 Supermargarate Margarate of soda - Barytes / -*<" Strontites - Lime - Base. 17-77 8.88 12.72 28.93 20.23 11.06 Potash. 100 8.85 100 100 100 100 100 100 100 100 100 8.68 8.78 8.60 8.77 Supermargarate of Human fat Sheep fat Ox fat Jaguar fat Goose fat If we compare the above numbers, we shall find 35 to be the prime equivalent of margaric acid. That of man is obtained under three dif- ferent forms. \st) In very fine long needles, disposed in flat stars. 2d, In very fine and very short needles, forming waved figures, like those of the margaric acid of carcasses. 3d, In very large brilliant crystals disposed in stars, similar to the margaric acid of the hog. The margaric acids of man and the hog re- semble each other ; as do those of the ox and the sheep ; and of the goose and the jaguar. The compounds with the bases are real soaps. The solution in alcohol affords the transparent soap of this country. Annales de Chimie et de Phys. several volumes. ACID (MECONIC). This acid is a con- stituent of opium. It was discovered by M. Sertuerner, who procured it in the following way: After precipitating the morphia, from a solution of opium, by ammonia, he added to the residual fluid a solution of the muriate of barytes. A precipitate is in this way formed, which is supposed to be a quadruple compound, of barytes, morphia, extract, and the meconic acid. The extract is removed by alcohol, and the barytes by sulphuric acid; when the meconic acid is left, merely in com- bination with a portion of the morphia ; and from this it is purified by successive solutions and evaporations. The acid, when sublimed, forms long colourless needles ; it has a strong affinity for the oxide of iron, so as to take it from the muriatic solution, and form with it a cherry-red precipitate. It forms a crystalliza- ble salt with lime, which is not decomposed by sulphuric acid ; and what is curious, it seems to possess no particular power over the human body, when received into the stomach. The essential salt of opium, obtained in M. De- rosne's original experiments, was probably the meconiate of morphia. Mr. Robiquet has made a useful modifica- tion of the process for extracting meconic acid. He treats the opium with magnesia, to sepa- rate the morphia, while meconiate of magnesia is also formed. The magnesia is removed by adding muriate of barytes, and the barytes is afterwards separated by dilute sulphuric acid. A larger proportion of moconic acid is thus obtained. Mr. Robiquet denies that meconic acid pre- cipitates iron from the muriate ; but, accord- ing to M. Vogel, its power of reddening solu- tions of iron is so great, as to render it a more delicate test of this metal, than even the ferro- prussiate of potash. To obtain pure meconic acid from the me- coniate of barytes, M. Choulaut triturated it in a mortar, with its own weight of glassy bo- racic acid. This mixture being put into a small glass flask, which was surrounded with sand in a sand pot, in the usual manner, and the red heat being gradually raised, the me- conic acid sublimed in the state of fine white scales or plates. It has a strong sour taste, which leaves behind it an impression of bitter- ness. It dissolves readily in water, alcohol, and ether. It reddens the greater number of vegetable blues, and changes the solutions of iron to a cherry-red colour. When these solu- tions are heated, the iron is precipitated in the state of protoxide. The meconiates examined by Choulant, are the following : 1**, Meconiate of potash. It crystallizes in four-sided tables, is soluble in twice its weight of water, and is composed of Meconic acid, 27 2.7 Potash, 60 6.0 Water, 13 100 It is destroyed by heat. 2<2, Meconiate of soda. It crystallizes in soft prisms, is soluble in five times its weight of water, and seems to effloresce. It is de- stroyed by heat It consists of ACI 46 ACI Acid, Soda, Water, 32 40 28 100 3.2 4.0 3d, Meconiate of ammonia. It crystallizes in star-form needles, which, when sublimed, lose their water of crystallization, and assume the shape of scales. The crystals are soluble in l their weight of water, and are composed of Acid, 40 2.03 Ammonia, 42 2.13 Water, 18 100 If two parts of sal ammoniac be triturated with three parts of meconiate of barytes, and heat be applied to the mixture, meconiate of ammonia sublimes, and muriate of barytes remains. 4R- URE. Specific jrtavity. Liq. Acid a 100. Dry acid in 100. Specific Gravity. Liq. Acid mlOO. Dry acid in 100. Spscific Gravity. Liq Acid in 1 00. Dry acid iti 100. Specific- Gravity. Liq. Acul nlOO. Dryaeii in 100. 1.5000 100 79.700 1.4189 75 59.775 1.2947 50 39.850 1.1403 25 19.925 1.4980 99 78.903 1.4147 74 58.978 1.2887 49 39.053 1.1345 24 19.128 1.4960 98 78.106 1.4107 73 58.181 1.2826 48 38.256 1.1286 23 18.331 1.4940 97 77-309 1.4065 72 57.384 1.2765 47 37.459 1.1227 22 17-534 1.4910 96 76.512 1.4023 71 56.587 .2705 46 36.662 1.1168 21 16.737 1.4880 95 75.715 1.3978 70 55-790 .2644 45 35.865 1.1109 20 15.940 1.4850 94 74.918 1.3945 69 54.993 .2583 44 35.068 1.1051 19 15.143 1.4820 93 74.121 1.3882 68 54.196 .2523 43 34.271 1.0993 18 14.346 1.4790 92 73.324 1.3833 67 53.399 .2462 42 33.474 1.0935 17 13.549 1.4760 91 72.527 1.3783 66 52.602 .2402 41 32.677 1.0878 16 12.752 1.4730 90 71-730 1.3732 65 51.805 .2341 40 31.880 1.0821 15 11.955 1.4700 89 70.933 1.3681 64 51.068 .2277 39 31.083 1.0764 14 11.158 1.4670 88 70.136 1.3630 63 50.211 .2212 38 30.286 1.0708 13 10.361 1.4640 87 69.339 1.3579 62 49.414 .2148 37 29.489 1.0651 12 9.564 1.4600 86 68.542 1.3529 61 48.617 .2084 36 28.692 1.0595 11 8.767 1.4570 85 67.745 1.3477 60 47.820 .2019 35 27.895 1.0540 10 7.970 1.4530 84 66.948 1.3427 59 47-023 .1958 34 27.098 1.0485 9 7.173 1.4500 83 66.155 1.3376 58 46.226 .1895 33 26.301 1.0430 8 6.376 1.4460 82 65.354 1.3323 57 45.429 .1833 32 25.504 1.0375 7 5.579 1.4424 81 64.557 1.3270 56 44.632 .1770 31 24.707 1.0320 6 4.782 1.4385 80 63.760 1.3216 55 43.835 .1709 30 23.900 1.0267 5 3.985 1.4346 79 62.963 1.3163 54 43.038 .1648 29 23.113 1.0212 4 3.188 1.4306 78 62.166 1.3110 53 42.241 .1587 28 22.316 1.0159 3 2.391 1.4269 77 61.369 1.3056 52 41.444 .1526 27 21.519 1.0106 2 1.594 1.4228 76 60.572 1.3001 51 40.647 1.1465 26 20.722 1.0053 1 0.797 AC I 59 ACI The column of dry acid shows the weight which any salifiable base would gain, by unit- ing with 100 parts of the liquid acid of the corresponding specific gravity. But it may be proper here to observe, that Sir H. Davy, in extending his views relative to the constitution of the dry muriates, to the nitrates, has sug- gested, that the latter when dry may be con- sidered as consisting, not of a dry nitric acid combined with the salifiable oxide, but of the oxygen and nitrogen of the nitric acid with the metal itself in triple union. A view of his reasoning will be found under the article SALT. He regards liquid nitric acid at its utmost density as a compound of 1 prime of hydrogen, 1 of nitrogen, and 6 of oxygen. The strongest acid that Mr. Kirwan could procure at 60 was 1.5543 ; but Rouelle pro- fesses to have obtained it of 1.583. Nitric acid should be of the specific gravity of 1.5, or a little more, and colourless. That of Mr. Kirwan seems to have con- sisted of one prime of real acid and one of water, when the suitable corrections are made ; but no common chemical use requires it of such a strength. The atomical relationships of Acid and Water were thus presented by me in a tabular form in the Journal of Science, for January, 1819, p. 248. Liquid Acid of 1.5. Sp. Grav. Atoms of dry Acid. Atoms of Water. 100 .5000 100 152 98 .4960 100 168 96 .4910 100 183 94 .4850 100 200 92 .4790 100 216 90 .4730 100 236 86 .4600 100 275 84 .4530 100 294 83 nearly. . 100 300 83 .4500 100 305 *n .3340 100 700 47 .2765 100 1000 The following table of boiling points has been given by Mr. Dalton. Acid of sp. gr. 1.50 boils at 210 1.45 1.42 1.40 1.35 1.30 1.20 1.15 240 248 247 242 236 226 219 At 1.42 specific gravity it distils unaltered. Stronger acid than that becomes weaker, and weaker acid stronger, by boiling. When the strong acid is cooled down to CO it con- cretes, by slight agitation, into a mass of the consistence of butter. This acid is eminently corrosive, and hence its old name of aquafortis. Its taste is sour and acrid. It is a deadly poison when introduced into the stomach in a concentrated state ; but when greatly diluted, it may be swallowed without inconvenience. It is often contami- nated, through negligence or fraud in the ma- nufacturer, with sulphuric and muriatic acids. Nitrate of lead detects both, or nitrate of barytes may be employed to determine the quantity of sulphuric acid, and nitrate of silver that of the muriatic. The latter proceeds from the crude nitre usually containing a quantity of common salt. When it is passed through a red-hot por- celain tube, it is resolved into oxygen and nitrogen, in the proportion above stated. It retains its oxygen with little force, so that it is decomposed by all combustible bodies. Brought into contact with hydrogen gas at a high tem- perature, a violent detonation ensues ; so that this must not be done without great caution. It inflames essential oils, as those of turpentine and cloves, when suddenly poured on them; but, to perform this experiment with safety, the acid must be poured out of a bottle tied to the end of a long stick, otherwise the operator's face and eyes will be endangered. If it be poured on perfectly dry charcoal powder, it ex- cites combustion, with the emission of copious fumes. By boiling it with sulphur it is decom- posed, and its oxygen, uniting with the sulphur, forms sulphuric acid. Proust has ascertained, that acid having the specific gravity 1 .48, has no more action on tin than on sand, while acid somewhat stronger or weaker acts furiously on the metal. Now, acid of 1.485, by my table, consists of one prime of real acid united with two of water, constituting, it would thus appear, a peculiarly powerful combination. Acid which takes up y^y of its weight of marble, freezes, according to Mr. Cavendish, at 2. When it can dissolve -^j^, it requires to be cooled to 41. 6 before congelation ; and when so much diluted as to take up only -5%^-, it congeals at 40.3. The first has a specific gravity of 1.330 nearly, and consists of 1 prime of dry acid + 7 of water ; the second has a spe- cific gravity of 1.420, and contains exactly one prime of dry acid -(- four of water ; while the third has a specific gravity of 1.215, consisting of one prime of acid -}- 14 of water. We perceive, that the liquid acid of 1.420, com- posed of 4 primes of water -f- one of dry acid, possesses the greatest power of resisting the influence of temperature to change its state. It requires the maximum heat to boil it, when it distils unchanged ; and the maximum cold to effect its congelation. The colour of the acid is affected by the quantity of nitric oxide it holds, and Sir H. Davy has given us the following table of pro- portions answering to its different hues. ACI 60 ACI COLOUR. Pale yellow, Bright yellow, Dark orange, Light olive, Dark olive, Bright green, Blue green, REAL ACID. 90.5 88.94 86.84 86.0 854 848 84.6 But these colours are not exact indications i of the state of the acid, for an addition of water will change the colour into one lower in the scale, so that a considerable portion of water will change the dark orange to a blue-green. Nitric acid is of considerable use in the arts. It is employed for etching on copper ; as a solvent of tin to form with that metal a mordant for some of the finest dyes ; in metallurgy and assaying ; in various chemical processes, on account of the facility with which it parts with oxygen and dissolves metals ; in medicine as a tonic, as also in form of vapour to destroy contagion. For the purposes of the arts it is commonly used in a diluted state, and conta- minated with the sulphuric and muriatic acids, by the name of aquafortis. Two kinds are found hi the shops, one called double aqua- fortis, which is about half the strength of nitric acid ; the other simply aquafortis, which is half the strength of the double. A compound made by mixing two parts of the nitric acid with one of muriatic, known formerly by the name of aqua rcgia, and now by that of nitro-muriatic acid^ has the pro- perty of dissolving gold and platina. On mix- ing the two acids, heat is given out, an effer- vescence takes place, and the mixture acquires an orange colour. This is likewise made by adding gradually to an ounce of powdered muriate of ammonia four ounces of double aquafortis, and keeping the mixture in a sand heat till the salt is dissolved ; taking care to avoid the fumes, as the vessel must be left open ; or by distilling nitric acid with an equal weight, or rather more, of common salt. On this subject we are indebted to Sir H. Davy for some excellent observations, pub- lished by him in the first volume of the Jour- nal of Science. If strong nitrous acid, satu- rated with nitrous gas, be mixed with a satu- rated solution of muriatic acid gas, no other effect is produced than might be expected from the action of nitrous acid of the same strength on an equal quantity of water ; and the mixed acid so formed has no power of action on gold or platina. Again, if muriatic acid gas, and nitrous gas, in equal volumes, be mixed toge- ther over mercury, and half a volume of oxy- gen be added, the immediate condensation will be no more than might be expected from the formation of nitrous acid gas. And when this is decomposed, or absorbed by the mercury, the muriatic acid gas is found unaltered, mixed with a certain portion of nitrous gas. NITRIC OXIDE. 1.2 2.96 5.56 6.45 7-1 7-76 8. WATEK, 8.3 8.10 7-6 7-55 7-5 7-44 7-4 It appears then that nitrous acid, and mu- riatic acid gas, have no chemical action on each other. If colourless nitric acid and mu- riatic acid of commerce be mixed together, the mixture immediately becomes yellow, and gains the power of dissolving gold and plati- num. If it be gently heated, pure chlorine arises from it, and the colour becomes deeper. If the heat be longer continued, chlorine still rises, but mixed with nitrous acid gas. When the process has been very long continued till the colour becomes very deep, no more chlo- rine can be procured, and it loses its power of acting upon platinum and gold. It is now nitrous and muriatic acids. It appears then from these observations, which have been very often repeated, that nitro-muriatic acid owes its peculiar properties to a mutual decomposi- tion of the nitric and muriatic acids ; and that water, chlorine, and nitrous acid gas, are the results. Though nitrous gas and chlorine have no action on each other when perfectly dry, yet if water be present there is an immediate decomposition, and nitrous acid and muriatic acid are formed. 118 parts of strong liquid nitric acid being decomposed in this case, yield 67 of chlorine. Aqua reg'ta does not oxidize gold and platina. It merely causes their combination with chlorine. A bath made of nitro-muriatic acid, diluted so much as to taste no sourer than vinegar, or of such a strength as to prick the skin a little, after being exposed to it for twenty minutes or half an hour, has been introduced by Dr.. Scott of Bombay as a remedy in chronic siphy- lis, a variety of ulcers and diseases of the skin, chronic hepatitis, bilious dispositions, general debility, and languor. He considers every trial as quite inconclusive where a ptyalism, some affection of the gums, or some very evi- dent constitutional effect, has not arisen from it. The internal use of the same acid has been recommended to be conjoined witli that of the partial or general bath. With the different bases the nitric acid forms nitrates. The nitrate of barytes, when perfectly pure, is in regular octaedral crystals, though it is sometimes obtained in small shining scales. It may be prepared by uniting bary- tes directly with nitric acid, or by decomposing the carbonate or sulphuret of barytes with this acid. Exposed to heat it decrepitates, and at length gives out its acid, which is decom- posed ; but if the heat be urged too far, the ACI 61 ACI barytcs is apt to vitrify with the earth of the crucible. It is soluble in 12 parts of cold, and 3 or 4 of boiling water. It is said to exist in some mineral waters. It consists of G-75 acid -j- 9.75 base. The nitrate of potash is the salt well known by the name of nitre or saltpetre- It is found ready formed in the East Indies, in Spain, in the kingdom of Naples, and elsewhere, in considerable quantities ; but nitrate of lime is still more abundant. Far the greater part of the nitrate made use of is produced by a com- bination of circumstances which tend to com- pose and condense nitric acid. This acid ap- pears to be produced in all situations, where animal matters are completely decomposed with access of air, and of proper substances with which it can readily combine. Grounds frequently trodden by cattle, and impregnated with then: excrements, or the walls of inha- bited places, where putrid animal vapours abound, such as slaughter-houses, drains, or the like, afford nitre by long exposure to the air. Artificial nitre beds are made by an at- tention to the circumstances in which this salt is produced by nature. Dry ditches are dug, and covered with sheds, open at the sides, to keep off the rain : these are filled with animal substances such as dung, or other excre- ments, with the remains of vegetables, and old mortar, or other loose calcareous earth; this substance being found to be the best and most convenient receptacle for the acid to com- bine with. Occasional watering, and turning up from time to time, are necessary to accele- rate the process, and increase the surfaces to which the air may apply ; but too much moist- ure is hurtful. When a certain portion of nitrate is formed, the process appears to go on more quickly ; but a certain quantity stops it altogether, and after this cessation the mate- rials will- go on to furnish more, if what is formed be extracted by lixiviation. After a succession of many months, more or less, ac- cording to the management of the operation, in which the action of a regular current of fresh air is of the greatest importance, nitre is found in the mass. If the beds contained much ve- getable matter, a considerable portion of the nitrous salt will be common saltpetre ; but if otherwise, the acid will, for the most pan, be combined with the calcareous earth. To extract the saltpetre from the mass of earthy matter, a number of large casks are prepared, with a cock at the bottom of each, and a quantity of straw within, to prevent its being stopped up. Into these the matter is put, together with wood-ashes, either strewed at top, or added during the filling. Boiling water is then poured on, and suffered to stand for some time ; after which it is drawn off, and other water added in the same manner, as long as any saline matter can be thus extracted. The weak brine is heated, and passed through other tubs, until it becomes of considerable strength. It is then carried to the boiler, and contains nitre and other salts ; the chief of which is common culinary salt, and sometimes muriate of magnesia. It is the property of nitre to be much more soluble in hot than cold water ; but common salt is very nearly as soluble in cold as in hot water. Whenever, therefore, the evaporation is carried by boiling; to a certain point, much of the common salt will fall to the bottom, for want of water to hold it in solution, though the nitre will re- main suspended by virtue of the heat. The common salt thus separated is taken out with a perforated ladle, and a small quantity of the fluid is cooled, from time to tune, that its con- centration may be known by the nitre which crystallizes in it. When the fluid is suf- ficiently evaporated, it is taken out and cooled, and great part of the nitre separates in crystals ; while the remaining common salt continues dissolved, because equally soluble in cold and in hot water. Subsequent evaporation of the residue will separate more nitre in the same manner. By the suggestion of Lavoisier, a much simpler plan was adopted ; reducing the crude nitre to powder, and washing it twice with water. This nitre, which is called nitre of the first boiling, contains some common salt ; from which it may be purified by solution in a small quantity of water, and subsequent evaporation ; for the crystals thus obtained are much less contaminated with common salt than before ; because the proportion of water is so much larger, with respect to the small quantity contained by the nitre, that very little of it will crystallize. For nice purposes, the solution and crystallization of nitre are re- peated four times. The crystals of nitre are usually of the form of six-sided flattened prisms, with diedral summits. Its taste is penetrating ; but the cold produced by placing the salt to dissolve in the mouth, is such as to predominate over the real taste at first. Seven parts of water dissolve two of nitre, at the temperature of sixty degrees ; but boiling water dissolves its own weight. 100 parts of alco- hol, at a heat of 176, dissolve only 2.9. Its constituents are nitric acid 6.75+P tasn 6. On being exposed to a gentle heat nitre fuses; and in this state being poured into moulds, so as to form little round cakes, or balls, it is called sal prunella, or crystal mi- neral. This salt powerfully promotes the com- bustion of inflammable substances. Two or three parts mixed with one of charcoal, and set on fire, burn rapidly ; azote and carbonic acid gas are given out, and a small portion of the latter is retained by the alkaline residuum, which was formerly called clyssus of nitre. Three parts of nitre, two of subcarbonate of potash, and one of sulphur, mixed together in a warm mortar, form the fulminating powder ; a small quantity of which, laid on a fire shovel* ACI ACI and held over the fire till it begins to melt, ex- plodes with a loud sharp noise. Mixed with sulphur and charcoal it forms gunpowder. See GUNPOWDER. Three parts of nitre, one of sulphur, and one of fine saw-dust, well mixed, constitute what is called the powder of fusion. If a bit of base copper be folded up and covered with this powder in a walnut-shell, and the powder be set on fire with a lighted paper, it will de- tonate rapidly, and fuse the metal into a glo- bule of sulphuret without burning the shell. Silex, alumina, and barytes, decompose this salt in a high temperature by uniting with its base. The alumina will effect this even after it has been made into pottery. The uses of nitre are various. Beside those already indicated, it enters into the composi- tion of fluxes, and is extensively employed in metallurgy; it serves to promote the com- bustion of sulphur in fabricating its acid ; it is used in the art of dyeing ; it is added to com- mon salt for preserving meat, to which it gives a red hue ; it is an ingredient in some frigori- fic mixtures ; and it is prescribed in medicine, as cooling, febrifuge, and diuretic ; and some have recommended it mixed with vinegar as a very powerful remedy for the sea scurvy. Nitrate of soda, formerly called cubic or quadrangular nitre^ approaches in its proper- ties to the nitrate of potash ; but differs from it in being somewhat more soluble in cold water, though less in hot, which takes up lit- tle more than its own weight ; in being inclined to attract moisture from the atmosphere ; and in crystallizing in rhombs, or rhomboidal prisms. It may be prepared by saturating soda with the nitric acid ; by precipitating nitric solutions of the metals, or of the earths, except barytes, by soda; by lixiviating and crystallizing the residuum of common salt dis- tilled with three-fourths its weight of nitric acid; or by saturating the mother waters of nitre with soda instead of potash. This salt has been considered as useless ; but professor Proust says, that five parts of it, with one of charcoal and one of sulphur, will burn three times as long as common powder, so as to form an economical composition for fire- works. It consists of 6.75 acid + 4. soda. Nitrate of strontian may be obtained in the same manner as that of barytes, with which it agrees in the shape of its crystals, and most of its properties. It is much more soluble, how- ever, requiring but four or five parts of water according to Vauquelin, and only an equal weight according to Mr. Henry. Boiling water dissolves nearly twice as much as cold. Applied to the wick of a candle, or added to burning alcohol, it gives a deep red colour to the flame. On this account it is useful in the art of pyrotechny. It consists of 6.75 acid -|- 6.5 strontites. Nitrate of lime, the calcareous nitre of older writers, abounds in the mortar of old buildings, particularly those that have been much exposed to animal effluvia, or processes in which azote is set free. Hence, it abounds in nitre beds, as was observed when treating of the nitrate of potash. It may also be prepared artificially, by pouring dilute nitric acid on carbonate of lime. If the solution be boiled down to a syrupy consistence, and exposed in a cool place, it crystallizes in long prisms, resembling bundles of needles diverging from a centre. These are soluble, according tc Henry, in an equal weight of boiling water, and twice their weight of cold ; soon deliquesce on exposure to the air, and are decomposed at a red heat. Fourcroy says, that cold water dissolves four times its weight, and that its own water of crystallization is sufficient to dissolve it at a boiling heat. It is likewise soluble in less than its weight of alcohol. By evaporating the aqueous solution to dryness, continuing the heat till the nitrate fuses, keeping it in this state five or ten minutes, and then pouring it into an iron pot previously heated, we obtain Bald-win's phosphorus. This, which is per- haps more properly nitrate of lime, being broken to pieces, and kept in a phial closely stopped, will emit a beautiful white light in the dark, after having been exposed some time to the rays of the sun. At present no use is made of this salt, except for drying some of the gases by attracting their moisture ; but it might be employed instead of the nitrate of potash for manufacturing aquafortis. The nitrate of ammonia possesses the pro- perty of exploding and being totally decom- posed, at the temperature of 600 ; whence it acquired the name ofnitrumjlammans. The readiest mode of preparing it is by adding carbonate of ammonia to dilute nitric acid till saturation takes place. If this solution be evaporated in a heat between 70 and 100, and the evaporation not carried too far, it crystallizes in hexaedral prisms terminating in very acute pyramids : if the heat rise to 212, it will afford, on cooling, long fibrous silky crystals : if the evaporation be carried so far as for the salt to concrete immediately on a glass rod by cooling, it will form a compact mass. According to Sir H. Davy, these differ but little from each other, except in the water they contain, their component parts being as follows : contains 5 f add 18.4 f 12.1 I9.3water-! 8.2 19.8 ( 5.7 All these are completely deliquescent, but they differ a little in solubility. Alcohol at 17(5 dissolves nearly 90.9 of its own weight. When dried as much as possible without decomposition, it consists of 6.75 acid -f- 2.125 ammonia -f- 1.125 water. - The chief use of this salt is for affording nitrous oxide on being decomposed by heaU See NITROGEN (OXIDE of). ACI Nitrate of magnesia, magnesian nitre, crys- tallizes in four-sided rhomboidal prisms, with oblique or truncated summits, and sometimes in bundles of small needles. Its taste is bitter, and very similar to that of nitrate of lime, but less pungent. It is fusible, and decomposable by heat, giving out first a little oxygen gas, then nitrous oxide, and lastly nitric acid. It deliquesces slowly. It is soluble in an equal weight of cold water, and in but little more of hot. so that it is scarcely crystallizable but by spontaneous evaporation. The two preceding species are capable of combining into a triple salt, an ammoniaco- magnesian nitrate, either by uniting the two in solution, or by a partial decomposition of either by means of the base of the other. This is slightly inflammable when suddenly heated; and by a lower heat is decomposed, giving out oxygen, azote, more water than it contained, nitrous oxide, and nitric acid. The residuum is pure magnesia. It is disposed to attract moisture from the air, but is much less deli- quescent than either of the salts that compose it, and requires eleven parts of water at 60 to dissolve it. Boiling water takes up more, so that it will crystallize by cooling. It consists of 78 parts of nitrate of magnesia, and 22 of nitrate of ammonia. From the activity of the nitric acid as a solvent of earths in analyzation, the nitrate of glucine is better known than any other of the salts of this new earth. Its form is either pulverulent, or a tenacious or ductile mass. Its taste is at first saccharine, and afterwards astringent. It grows soft by exposure to heat, soon melts, its acid is decomposed into oxygen and azote, and its base alone is left behind. It is very soluble and very deliquescent. Nitrate, or rather supernitrate, of alumina crystallizes, though with difficulty, in thin, soft, pliable flakes. It is of an austere and acid taste, and reddens blue vegetable colours. It may be formed by dissolving in diluted nitric acid, with the assistance of heat, fresh precipitated alumina, well washed but not dried. It is deliquescent, and soluble in a very small portion of water. Alcohol dissolves its own weight. It is easily decomposed by heat. Nitrate of zircone was first discovered by Klaproth, and has since been examined by Guyton-Morveau and Vauquelin. Its crystals are small, capillary, silky needles. Its taste is astringent. It is easily decomposed by fire, very soluble in water, and deliquescent. It may be prepared by dissolving zircone in strong nitric acid ; but, like the preceding species, the acid is always in excess. Nitrate of yttria may be prepared in a similar manner. Its taste is sweetish and astringent. It is scarcely to be obtained in crystals ; and if it be evaporated by too strong a heat, the salt becomes soft like honey, and on cooling concretes into a stony mass. See SALT. 63 ACI ACID (NITROUS). This acid is obtained by exposing nitrate of lead to heat in a glass retort. Pure nitrous acid comes over in the form of an orange-coloured liquid. It is so V volatile as to boil at the temperature of 82. Its specific gravity is 1.450. When mixed with water it is decomposed, and nitrous gas is disengaged, occasioning effervescence. It is composed of one volume of oxygen united with two of nitrous gas. It therefore consists ulti- mately, by weight, of 1.75 nitrogen + 4 oxygen ; by measure, of 2 oxygen -f- 1 nitro- gen. The various coloured acids of nitre are not nitrous acids, but nitric acid impregnated with nitrous gas, the deutoxide of nitrogen or azote. (See the preceding table of Sir H. Davy, concerning the coloured acid). ACID (HYPONITROUS). It appears, from the experiments of M. Gay Lussac, that there exists a third acid, formed of 100 azote and 150 oxygen. When into a test tube filled with mercury, we pass up from 500 to 600 volumes of deutoxide of azote, a little alkaline water, and 100 parts of oxygen gas, we obtain an absorption of 500, proceeding from the con- densation of the 100 parts of oxygen with 400 of deutoxide of azote. Now these 400 parts are composed of 200 azote and 200 oxygen ; consequently the new acid is composed of azote and oxygen, in the ratio of 100 to 150, as we have said above. It is the same acid, according to M. Gay Lussac, which is produced on leaving for a long time a strong solution of potash in contact with deutoxide of azote. At the end of three months he found that 100 parts of deutoxide of azote were reduced to 25 of protoxide of azote, and that crystals of Tiyponitrite (pernitrite) were formed. Hyponitrous acid (called pernitrous by the French chemists), cannot be insulated. As soon as we lay hold, by an acid, of the potash with which it is associated, it is transformed into deutoxide of azote, which is disengaged, and into nitrous or nitric acid which remains in solution. ACID (NITRO-LEUCIC). Lencine is capable of uniting to nitric acid, and forming a compound, which M. Braconnot has called the nitro-leucic acid. When we dissolve leu- cine in nitric acid, and evaporate the solution to a certain point, it passes into a crystalline mass, without any disengagement of nitrous vapour, or of any gaseous matter : If we press this mass between blotting paper, and redis- solve it in water, we shall obtain from this, by concentration, fine, divergent, and nearly colourless needles. These constitute the new acid. It unites to the bases forming salts, which fuse on red-hot coals. The nitro-leu- cates of lime and magnesia are unalterable in the air. ACID (NITRO-SACCHARIC). When we heat the sugar of gelatine with nitric acid, it dissolves without any apparent disengage- ment of gas, and if we evaporate this solution ACI 64 ACI to a proper degree, it forms, on cooling, a crystalline mass. On pressing this mass be- tween the folds of blotting paper, and recry. stallizing them, we obtain beautiful prisms, colourless, transparent, and slightly striated. These crystals are very different from those which serve to produce them; constitute, according to M. Braconnot, a true acid, which results from the combination of the nitric acid itself, witli the sweet matter of which the first crystals are formed. M. Thenard conceives it is the nitrous acid which is present. Nitro-saccharic acid has a taste similar to that of the tartaric ; only it is a little sweetish. Exposed to the fire in a capsule, it froths much, and is decomposed with the diffusion of a pungent smell. Thrown on burning coals it acts like saltpetre. It produces no change in saline solutions. Finally, it combines with the bases, and gives birth to salts which pos- sess peculiar properties. For example, the salt which it forms with lime is not deliquescent, and is very little soluble in strong alcohol. That which it produces with the oxide of lead detonates to a certain degree by the action of heat. Ann. de Chimie et de Phys. xiii. 1 1 3. ACID (NITRIC, OXYGENIZED). In our general remarks on acidity, we have de- scribed M. Thenard's newly discovered method of oxygenizing the liquid acids. The first that he examined was the combination of nitric acid and oxygen. When the peroxide of barium, prepared by saturating barytes with oxygen, is moistened, it falls to powder, without much increase of temperature. If in this state it be mixed with seven or eight times its weight of water, and dilute nitric acid be gradually poured upon it, it dissolves gradually by agi- tation, without the evolution of any gas. The solution is neutral, or has no action on turn- sole or turmeric. When we add to this solution the requisite quantity of sulphuric acid, a copious precipitate of sulphate of barytes falls, and the filtered liquor is merely water, holding in solution oxygenized nitric acid. This acid is liquid and colourless: it strongly reddens turnsole, and resembles in all its properties nitric acid. When heated it immediately begins to dis- charge oxygen ; but its decomposition is never complete, unless it be kept boiling for some time. The only method which M. Thenard found successful for concentrating it, was to place it in a capsule, under the receiver cf an air-pump, along with another capsule full of lime, and to exhaust the receiver. By this means he obtained an acid sufficiently concen- trated to give out 1 1 times its bulk of oxygen gas. This acid combines very well with barytes, potash, soda, ammonia, and neutralizes them. When crystallization commences in the liquid, by even a spontaneous evaporation, these salts are instantly decomposed. The exhausted re- ceiver also decomposes them. The oxygenized nitrates, when changed into common nitrates, do not change the state of their neutralization. Strong solution of potash poured into their solutions decomposes them. Oxygenized nitric acid does not act on gold ; but it dissolves all the metals which the com- mon acid acts on, and when it is not too concen- trated, it dissolves them without effervescence. Deutoxide or peroxide of barium contains just double the proportion of oxygen that its prot- oxide does. But M. Thenard says, that the barytes obtained from the nitrate by ignition contains always a little of the peroxide. When oxygenized nitric acid is poured upon oxide of silver, a strong effervescence takes place, owing to the disengagement of oxygen. One portion of the oxide of silver is dissolved, the other is reduced at first, and then dissolves likewise, provided the quantity of acid be sufficient. The solution being completed, if we add potash to it, by little and little, a new effervescence takes place, and a dark violet precipitate falls ; at least this is always the colour of the first deposit. It is insoluble in ammonia, and, according to all appearance, is a protoxide of silver. As soon as we plunge a tube containing oxide of silver into a solution of oxygenized nitrate of potash, a violent effervescence takes place, the oxide is reduced, the silver preci- pitates, the whole oxygen of the oxygenized nitrate is disengaged at the same time with that of the oxide; and the solution, which contains merely common nitrate of potash, remains neutral, if it was so at first. But the most unaccountable phenomenon is the following: If silver, in a state of extreme division (fine filings), be put into the oxy- genized nitrate, or oxygenized muriate of potash, the whole oxygen is immediately dis- engaged. The silver itself is not attacked, and the salt remains neutral as before. Iron, zinc, copper, bismuth, lead, and platinum, likewise possess this property of separating the oxygen of the oxygenized nitrate. Iron and zinc are oxidized, and at the same time occasion the evolution of oxygen. The other metals are not sensibly oxidized. They were all employed in the state of filings. Gold scarcely acts. The peroxides of manganese and of lead decompose these oxynitrates. A very small quantity of these oxides, in powder, is sufficient to drive off the whole oxygen from the saline solution. The effervescence is lively. The peroxide of manganese undergoes no al- teration. Though nitric acid itself has no action on the peroxides of lead and manganese, th^ oxygenized acid dissolves both of them with the greatest facility. The solution is accom- panied by a great disengagement of oxygen gas. The effect of silver, he thinks, may pro- bably be ascribed to voltaic electricity. The remarks appended to our account of M. Thenard's oxygenized muriatic acid are AC I 65 ACI vqually applicable to the nitric ; but the phe- nomena are too curious to be omitted in a work of the present kind. ACID (OLEIC). When potash and hog's lard are saponified, the margarate of the alkali separates in the form of a pearly-looking solid, while the fluid fat remains in solution, com- bined with the potash. When the alkali is separated by tartaric acid, the oily principle of fat is obtained, which M. Chevreul purifies by saponifying it again and again, recovering it two or three times ; by which means the whole of the margarine is separated. As this oil has the property of saturating bases and forming neutral compounds, he has called it oleic acid. In his sixth memoir, he gives the following table of results: 100 Oleic acid of human fat Saturate Barytes Strontian Lead 2G.OO 19.41 82.48 100 Oleic acid of sheep fat 26.77 19.38 81.81 100 Oleic acid of ox fat 28.93 19.41 81.81 100 Oleic acid of goose fat 26.77 19.38 81.34 100 Oleic acid of hog fat 27.00 29.38 81.80 Oleic acid is an oily fluid without taste and smell. Its specific gravity is 0.914. It is generally soluble in its own weight of boiling alcohol, of the specific gravity of 0.7952; but some of the varieties are still more soluble. 100 of the oleic acid saturate 16.58 of potash, 10.11 of soda, 7.52 of magnesia, 14. 83 of zinc, and 13.93 peroxide of copper. M. Chevreul's experiments have finally induced him to adopt the quantities of 100 acid to 27 barytes, as the most correct ; whence calling barytes 9-75, we have the equivalent prime of oleic acid = 36.0. ACID (OXALIC). This acid may be obtained from sugar in the following way : To six ounces of nitric acid in a stoppered re- tort, add, by degrees, one ounce of lump sugar coarsely powdered. A gentle heat may be applied during the solution, and nitric oxide will be evolved in abundance. When the whole of the sugar is dissolved, distil off a part of the acid, till what remains in the retort has a syrupy consistence, and this will form regu- lar crystals, amounting to 58 parts from 100 of sugar. These crystals must be dissolved in water, recrystallized, and dried on blotting paper. A variety of other substances afford the oxalic acid when treated by distillation with the nitric. Bergman procured it from honey, gum-arabic, alcohol, and the calculous con- cretions in the kidneys and bladders of ani- mals. Scheele and Hermbstadt from sugar of milk. Scheele from a sweet matter contained in fat oils, and also from the uncrystallizable part of the juice of lemons. Hermbstadt from the acid of cherries, and the acid of tartar. Goettling from beech wood. Kohl from the residuum in the distillation of ardent spirits. Westrumb not only from the crystallized acids of currants, cherries, citrons, raspberries, but also from the saccharine matters of these fruits, and from the uncrystallizable parts of the acid juices. Hoffmann from the juice of the bar- berry ; and Berthollet from silk, hair, tendons, wool; also from other animal substances, especially from the coagulum of blood, whites of eggs, and likewise from the amylaceous and glutinous parts of flour. M. Berthollet ob- serves, that the quantity of the oxalic acid obtained by treating wool with nitric acid was very considerable, being above half the weight of the wool employed. He mentions a differ- ence which he observed between animal and vegetable substances thus treated with nitric acid, namely, that the former yielded, beside ammonia, a large quantity of an oil which the nitric acid could not decompose ; whereas the oily parts of vegetables were totally destroyed by the action of this acid : and he remarks, that in this instance the glutinous part of flour resembled animal substances, whereas the amylaceous part of the flour retained its vege- table properties. He further remarks, that the quantity of oxalic acid furnished by vege- table matters thus treated its proportionable to their nutritive quality, and particularly that, from cotton, he could not obtain any sensible quantity. Deyeux, having cut with scissars the hairs of the chick pea, found they gave out an acid liquor, which, on examination, proved to be an aqueous solution of pure oxalic acid. Proust and other chemists had before observed, that the shoes of persons walking through a field of chick peas were corroded. Braconnot has lately shown, that the crust- aceous lichens, such as pertusaria communis, urceolaria scruposa, isidium corallinum, pa- tellaria tartarca, ventosa rnbra, hematomma, bceomices ericetorum, squamaria lentigera, placodium radiosum, ochroleucum, psora Can- dida, contain nearly one half their weight of oxalate of lime, a substance which is to these plants what carbonate of lime is to corallines, and phosphate of lime to animal bones. Hum- boldt says, these are the lichens by which the earth void of vegetation in the north of Peru begins to be covered ; by their means vegeta- tion seems to commence on the barren surface of rocks. By the successive action of solution of carbonate of soda, aided by a boiling heat, the oxalate of lime in these plants is converted into a carbonate, while oxalate of soda remains dissolved. Oxalic acid crystallizes in quadrilateral prisms, the sides of which are alternately broad and narrow, and summits diedral ; or, if crystallized rapidly, in small irregular needles. They are efflorescent in dry air, but attract a little humidity if it be damp ; are soluble in ACI 66 ACI one part of hot and two of cold water ; and are decomposable by a red heat, leaving By pouring a solution of the preceding salt into alcohol, a sesquiphosphate is obtained, in the form of a light white powder, containing J times as much acid as the subphosphate. The phosphate of strontian differs from the preceding in being soluble in an excess of its acid. Phosphate of lime is very abundant in the native state. See APATITE. It likewise con- stitutes the chief part of the bones of all ani- mals. Phosphate of lime is very difficult to fuse, but in a glasshouse furnace it softens, and acquires the semitransparency and grain of porcelain. It is insoluble in water, but when well calcined, forms a kind of paste with it, as in making cupels. Besides this use of it, it is employed for polishing gems and metals, for absorbing grease from cloth, linen, or paper, and for preparing phosphorus. In medicine it has been strongly recommended against the rickets by Dr. Bonhomme of Avignon, either alone or combined with phosphate of soda. The burnt hartshorn of the shops is a phos- phate of lime. An acidulous phosphate of lime is found in human urine, and may be crystallized in small silky filaments, or shining scales, which unite together into something like the consistence of honey, and have a perceptibly acid taste. It may b2 prepared by partially decomposing the calcareous phosphate of bones by the sulphuric, ACI 70 ACI nitric, or muriatic acid, or by dissolving that phosphate in phosphoric acid. It is soluble in water, and crystallizable. Exposed to the action of heat, it softens, liquefies, swells up, becomes dry, and may be fused into a trans- parent glass, which is insipid, insoluble, and unalterable in the air. In these characters it differs from the glacial acid of phosphorus. It is partly decomposable by charcoal, so as to afford phosphorus. By pouring phosphate of soda into muriate of lime, Berzelius obtained a phosphate of lime consisting of acid 100, lime 84.53. The exact proportions are, Phosphoric acid =9 = 100 Lime 3. 5x2 = 7= 78 nearly. The phosphate of potash is very deliques- cent, and not crystallizable, but condensing into a kind of jelly. Like the preceding spe- cies, it first undergoes the aqueous fusion, swells, dries, and may be fused into a glass ; but this glass deliquesces. It has a sweetish saline taste. The phosphate of soda is now commonly prepared by adding to the acidulous phosphate of lime as much carbonate of soda in solution as will fully saturate the acid. The carbonate of lime which precipitates, being separated by filtration, the liquid is duly eva- porated so as to crystallize the phosphate of soda ; but if there be not a slight excess of alkali, the crystals will not be large and regu- lar. The crystals are rhomboidal prisms of different shapes ; efflorescent ; soluble in three parts of cold and IA of hot water. They are capable of being fused into an opaque white glass, which may be again dissolved and crys- tallized. It may be converted into an acidu- lous phosphate by an addition of acid, or by either of the strong acids, which partially, but not wholly, decompose it. As its taste is simply saline, without any thing disagreeable, it is much used as a purgative, chiefly in broth, in which it is not distinguishable from com- mon salt. For this elegant addition to our pharmaceutical preparations, we are indebted to Dr. Pearson. In assays with the blowpipe \ it is of great utility ; and it has been used in- stead of borax for soldering. In crystals, this salt is composed, according to Berzelius, of phosphoric acid 20.33, soda 17.67, water 62.00 ; and in the dry state, of acid 53.48, soda 46.52. If it be represented by 1 atom of acid = 9 -f- 2 atoms soda = 8, then 100 of the dry salt will consist of acid 53, base 47 ; and in the crystallized state, of Water 24 atoms 27 61.4 Acid 1 9 20.4 Soda 2 8 18.2 100.0 which presents a good accordance with the ex- perimental results of the accurate Berzelius. The phosphate of ammonia crystallizes in prisms with four regular sides, terminating in pyramids, and sometimes in bundles of small needles. Its taste is cool, saline pungent, and urinous. On the fire it comports itself like the preceding species, except that the whole of its base may be driven off by a continuance of the heat, leaving only the acid behind. It is but little more soluble in hot water than in cold, which takes up a fourth of its weight. It is pretty abundant in human urine. It is an excellent flux both for assays and the blow- pipe, and in the fabrication of coloured glass and artificial gems- Phosphate of magnesia crystallizes in irre- gular hexaedral prisms, obliquely truncated ; but is commonly pulverulent, as it effloresces very quickly. It requires fifty parts of water to dissolve it. Its taste is cool and sweetish. This salt too is found in urine. Fourcroy and Vauquelin have discovered it likewise in small quantity in the bones of various animals, though not in those of man. The best way of preparirj; it is by mixing equal parts of the solutions of phosphate of soda and sulphate of magnesia, and leaving them some time at rest, when the phosphate of magnesia will crystal- lize, and leave the sulphate of soda dissolved. An ammoniaco-magnesian phosphate has been discovered in an intestinal calculus of a horse by Fourcroy, and since by Bartholdi, and likewise by the former in some human urinary calculi. See CALCULUS. Notwithstanding the solubility of the phosphate of ammonia, this triple salt is far less soluble than the phos- phate of magnesia. It is partially decompo- sable into phosphorus by charcoal, in conse- quence of its ammonia. The phosphate of glucine has been examined by Vauquelin, who informs us, that it is a white powder, or mucilaginous mass, without any perceptible taste ; fusible, but not decom- posable by heat ; unalterable in the air, and insoluble unless in an excess of its acid. It has been observed, that the phosphoric acid, aided by heat, acts upon silex ; and we may add, that it enters into many artificial gems in the state of a saliceous phosphate. See SALT. ACID (PINIC). In the colophony of France (rosin), derived in all probability from the pinus maritima or pinaster, M. Baup has found a substance which crystallizes in trian- gular plates, soluble in about four parts of alcohol, but insoluble in water. It reacts like an acid, and neutralizes alkaline matter. He calls it Pinic acid. Annaks de Chim. et de Phys. xxxi. ACID (PRUSSIC). This acid and its combinations have been lately investigated by MM. Gay Lussac and Vauquelin in France, and Mr. Porrett in England, who have hap- pily succeeded in removing the veil which con- tinued to hang over this department of che- mistry. To a quantity of powdered prussian blue ACI 71 ACI xfiftused in boiling water, let red oxide of mer- cury be added in successive portions till the blue colour is destroyed. Filter the liquid, and concentrate by evaporation till a pellicle appears. On cooling, crystals of prussiate or cyanide of mercury will be formed. Dry these, and put them into a tubulated glass retort, to the beak of which is adapted a horizontal tube about two feet long, and fully half an inch wide at its middle part. The first third part of the tube next the retort is filled with small pieces of white marble, the two other thirds with fused muriate of lime. To the end of this tube is adapted a small receiver, which should be artificially refrigerated. Pour on the crys- tals muriatic acid, in rather less quantity than is sufficient to saturate the oxide of mercury which formed them. Apply a very gentle heat to the retort. Prussic acid, named" hydrocy- anic by M. Gay Lusae, will be evolved in vapour, and will condense in the tube. What- ever muriatic acid may pass over with it, will be abstracted by the marble, while the water will be absorbed by the muriate of lime. By means of a moderate heat applied to the tube, the prussic acid may be made to pass succes- sively along ; and after being left some time in contact with the muriate of lime, it may be finally driven into the receiver. As the car- bonic acid evolved from marble by the muriatic is apt to carry off some of the prussic acid, care should be taken to conduct the heat so as to prevent the distillation of this mineral acid. Prussic acid thus obtained has the following properties. It is a colourless liquid, possess- ing a strong odour ; and the exhalation, if in- cautiously snuffed up the nostrils, may pro- duce sickness or fainting. Its taste is cooling at first, then hot, asthenic in a high degree, and a true poison. Its specific gravity at 44^, is 0.7058 ; at 64 it is 0.6969. It boils at 81^, and congeals at about 3. It then crys- tallizes regularly, and affects sometimes the fibrous form of nitrate of ammonia. The cold which it produces, when reduced into vapour, even at the temperature of 68, is sufficient to congeal it. This phenomenon is easily pro- duced by putting a small drop at the end of a slip of paper or a glass tube. Though repeat- edly rectified on pounded marble, it retains the property of feebly reddening paper tinged blue with litmus. The red colour disappears as the acid evaporates. The specific gravity of its vapour, experi- mentally compared to that of air, is 0.9476. By calculation from its constituents, its true specific gravity comes out 0.9360, which dif- fers from the preceding number by only one- hundredth part. This small density of prus- sic acid, compared with its great volatility, furnishes a new proof that the density of va- pours does not depend upon the boiling point of the liquids that furnish them, but upon their peculiar constitution. M. Gay Lussac analyzed this acid by in- troducing its vapour at the temperature of 86 into a jar, two-thirds filled with oxygen, over warm mercury. When the temperature of the mercury was reduced to that of the ambient air, a determinate volume of the gaseous mix- ture was taken and washed in a solution of potash, which abstracts the prussic acid, and leaves the oxygen. This gaseous mixture may, after this inspection, be employed with- out any chance that the prussic acid will con- dense, provided the temperature be not too low ; but during M. Gay Luss?,c's experiments it was never under Tl%. A known volume was introduced into a Volta's eudiometer, with platina wires, and an electric spark was passed across the gaseous mixture. The combustion is lively, and of a bluish-white colour. A white prussic vapour is seen, and a diminution of volume takes place, which is ascertained by measuring the residue in a graduated tube. This being washed with a solution of potash or barytes, suffers a new diminution from the absorption of the carbonic acid gas formed. Lastly, the gas which the alkali has left is analyzed over water by hydrogen, and it is ascertained to be a mixture of nitrogen and oxygen, because this last gas was employed in excess. The following are the results, referred to prussic acid vapour. Vapour - - - - 100 Diminution after combustion - 78.5 Carbonic acid gas produced - 101.0 Nitrogen - - - - 46.0 Hydrogen - 55.0 During the combustion a quantity of oxy- gen disappears, equal to about 1^ of the va- pour employed. The carbonic acid produced represents one volume ; and the other fourth is supposed to be employed in forming water ; for it is impossible to doubt that hydrogen enters into the composition of prussic acid. From the laws of chemical proportions, M. Gay Lussac concludes that prussic acid vapour contains just as much carbon as will form its own bulk of carbonic acid, half a volume of nitrogen, and half a volume of hydrogen. This result is evident for the carbon ; and though, instead of 50 of nitrogen and hydrogen, which ought to be the numbers according to the sup- position, he obtained 46 for the first, and 55 for the second, he ascribes the discrepancy to a portion of the nitrogen having combined with the oxygen to form nitric acid. The density of carbonic acid gas being, ac- cording to M. Gay Lussac, 1.5196, and that of oxygen 1.1036, the density of the vapour of carbon is 1.5196 1.1036 =0.4160. Hence 1 volume carbon - - =0.4160 Half a volume of hydrogen = 0.0366 Half a volume of nitrogen = 0.4845 Sum 0.9371 Thus, according to the analytical statement, AC I ACI the density of prussic vapour is 0.9371, and by direct experiment it was found to be 0.9476. It may therefore be inferred from this near co- incidence, that prussic acid vapour contains one volume of the vapour of carbon, half a volume of nitrogen, and half a volume of hydrogen, condensed into one volume, and that no other substance enters into its composition. M. Gay Lussac confirmed the above deter- mination, analyzing prussic acid by passing its vapour through an ignited porcelain tube con- taining a coil of fine iron wire, which facilitates the decomposition of this vapour, as it does with ammonia. No trace of oxygen could be found in prussic acid. And again, by trans- mitting the acid in vapour over ignited per- oxide of copper in a porcelain tube, he came to the same conclusion with regard to its con- stituents. They are, One volume of (he vapour of carbon, Half a volume of hydrogen, Half a volume of nitrogen, condensed into one volume ; or in weight, Carbon Nitrogen Hydrogen 44.39 51.71 3.90 100.00 This acid, when compared with the other animal products, is distinguished by the great quantity of nitrogen it contains, by its small quantity of hydrogen, and especially by the absence of oxygen. When this strong acid is kept in well-closed vessels, even though no air be present, it is sometimes decomposed in less than an hour. It has been occasionally kept 15 days without alteration ; but it is seldom that it can be kept longer, without exhibiting signs of decompo- sition. It begins by assuming a reddish-brown colour, which becomes deeper and deeper, and it gradually deposits a considerable carbon- aceous matter, which gives a deep colour to both water and acids, and emits a strong smell of ammonia. If the bottle containing the prussic acid be not hermetically sealed, no- thing remains but a dry charry mass, which gives no colour to water. Thus a prussiate of ammonia is formed at the expense of a part of the acid, and an azoturet of carbon. When potassium is heated in prussic acid vapour mixed with hydrogen or nitrogen, theie is ab- soiption without inflammation, and the metal is converted into a grey spongy substance, which melts, and assumes a yellow colour. Supposing the quantity of potassium em- ployed capable of disengaging from water a volume of hydrogen equal to 50 parts, we find after the action of the potassium, 1. That the gaseous mixture has experienced a diminution of volume amounting to 50 parts : 2. On treating this mixture with potash, and analyzing the residue by oxygen, that 50 part* of hydrogen have been produced: 3. And con- sequently that the potassium has absorbed 100 parts of prussic vapour ; for there is a dimi- nution of 50 parts, which would obviously have been twice as great had not 50 parts of hydrogen been disengaged. The yellow mat- ter is prussiate of potash ; properly a prusside of potassium, analogous in its formation to the chloride and iodide, when muriatic and hy- driodic gases are made to act on potassium. The base of prussic acid thus divested of its acidifying hydrogen, might be called, agree- ably to the same chemical analogy, prussine. M. Gay Lussac styles it cyanogen, because it is the principle which generates blue ; or lite- rally the blue-maker. Like muriatic and hydriodic acids, this one contains half its volume of hydrogen. The only difference is, that the former have, in the present state of our knowledge, simple radicals, chlorine and iodine, while that of the latter is a compound of one volume vapour of carbon, and half a volume of nitrogen. This radical forms true cyanides with metals. . The cyanide of potassium gives a very al- kaline solution in water, even when a great excess of hydrocyanic vapour has been present at its formation. In this respect it differs from the chlorides and iodides of that metal, which are perfectly neutral. Knowing the composi- tion of prussic acid, and that potassium sepa- rates from it as much hydrogen as from water, it is easy to find its proportional number or equivalent to oxygen. We must take such a quantity of prussic acid that its hydrogen may saturate 10 of oxygen. Thus we find the prime equivalent of this acid to be 33.846 ; and sub- tracting the weight of hydrogen, there remains 32.52 for the equivalent of cyanogen or prus- sine. But if we reduce the numbers repre- senting the volumes to the prime equivalents adopted in this Dictionary, viz. 0.75 for car- bon, 0.125 for hydrogen, and 1.75 for nitro- gen, we shall have the relation of volumes slightly modified. Since the fundamental com- bining ratio of oxygen to hydrogen in bulk is ^ to 1, we must multiply the prime equivalent by half the specific gravity of oxygen, and we obtain the following numbers : 1 volume car. = 0-75 X 0.5555 = 0.41663 | volume hyd. = 0.125 X 0.5555 = 0.03471 i volume nitr. = L ? 5 x ' 5555 = 0.48610 2 Sum = 0.93744 Or, as is obvious by the above calculation, we may take 2 primes of carbon, 1 of hydro- gen, and J of nitrogen, which directly added together will give the same results, since by AC I ACI tso doing we merely take away the common multiplier 0.5555. Thus we have 2 primes carbon :,$ -& 1 prime hydrogen 1 prime nitrogen 1.500 0.125 1.750 3.375 Which reduced to proportions per cent, give of Carbon ' 5 - - 44.444 Hydrogen - - 3.737 Nitrogen - * > - 51.818 100.000 Barytes, potash, and soda, combine with cyanogen, forming true cyanides of these al- kaline oxydes ; analogous to what are vulgarly called oxymuriates of lime, potash, and soda. The red oxide of mercury acts so powerfully on prussic acid vapour, when assisted by heat, that the compound which ought to result is destroyed by the heat disengaged. The same thing happens when a little of the concentrated acid is poured upon the oxide. A great ele- vation of temperature takes place, which would occasion a dangerous explosion if the experi- ment were made upon considerable quantities. When the acid is diluted, the oxide dissolves rapidly, with a considerable heat, and without the disengagement of any gas. The substance formerly called prussiate of mercury is gene- rated, which when moist may, like the mu- riates, still retain that name ; but when dry is a cyanide of the metal. When the cold oxide is placed in contact with the acid, dilated into a gaseous form by hydrogen, its vapour is absorbed in a few mi- nutes. The hydrogen is unchanged. When a considerable quantity of vapour has thus been absorbed, the oxide adheres to the side of the tube, and on applying heat, water is obtained. The hydrogen of the acid has here united with the oxygen of the oxide to form the water, while their two radicals combine. Red oxide of mercury becomes an excellent reagent for detecting prussic acid. By exposing the dry cyanide of mercury to heat in a retort, the radical cyanogen is ob- tained. See CYANOGEN. On subjecting hydrocyanic, or prussic acid, to the action of a battery of 20 pairs of plates, much hydrogen is disengaged at the negative .pole; and cyanogen at the positive, which re- mains dissolved in the acid. This compound should be regarded as a hypoprussic or prus- sous acid. Since potash by heat separates the hydrogen of the prussic acid, we see that in ex- posing a mixture of potash and animal matters to a high temperature, a true cyanide of potash is obtained, formerly called the prussian or phlogisticated -alkali. When cyanide of po- tassium is dissolved in water, hydrocyanate of potash is produced, which is decomposed by the acids without generating ammonia or car- bonic acid; but when cyanide of potash dis- solves in water, no change takes place ; and neither ammonia, carbonic acid, nor hydro- cyanic vapour is given out, unless an acid be added. These are the characters which di- stinguish a metallic cyanide from the cyanide of an oxide. From the experiments of M. Magendie it appears, that the pure hydrocyanic acid is the most violent of all poisons. When a rod dipped into it is brought in contact with the tongue of an animal, death ensues before the rod can be withdrawn. If a bird be held a moment over the mouth of a phial containing this acid, it dies. In the Annales de Chimie for 1814 we find this notice : M. B., professor of chemistry, left by accident on a table a flask containing alcohol impregnated with prussic acid; the servant, enticed by the agreeable flavour of the liquid, swallowed a small glass of it. In two minutes she dropped down dead, as if struck with apoplexy. The body was not examined. " Scharinger, a professor at Vienna," says Orfila, " prepared six or seven months ago a pure and concentrated prussic acid ; he spread a certain quantity of it on his naked arm, and died a little tune thereafter." Dr. Magendie has, however, ventured to introduce its employment into medicine. He found it beneficial against phthisis and chro- nic catarrhs. His formula is the follow- ing: Mix one part of the pure prussic or hy- drocyanic acid of M. Gay Lussac with 8^ of water by weight. To this mixture he gives the name of medicinal prussic acid. Of this he takes 1 gros. or 59 gr. Troy. Distilled water, 1 lb. or 7560 grs. Pure sugar, l oz or 708f gr. And mixing the ingredients well together, he administers a table-spoonful every morning and evening. The simplest, and perhaps most economical, process which I know for obtaining hydro- cyanic acid of moderate strength, for most chemical, and all medical purposes, is to dis- solve ferroprussiate of potash in water, and to add to the solution, contained in a retort, as much sulphuric acid as there was salt em- ployed. Distilling with a gentle heat, hydro- cyanic acid is obtained. If it be tinged blue with a little iron, this may be separated either by filtration or redistillation. Another mode which I have found to afford an acid which keeps well, is to transmit a current of sulphu- retted hydrogen gas through a solution of prussiate of mercury, till the whole metal be separated in the state of sulphuret. This subsides and leaves liquid hydrocyanic acid mixed with some sulphuretted hydrogen, which may be removed by agitation with car- bonate of lead. This is merely a modification of Vauquelin's original process, in which sul- phuretted hydrogen gas was made to act on ACI ACI the solid cyanide of mercury contained in a glass tube. Hydrocyanic acid is formed in a great many chemical operations ; as for instance, by trans- mitting ammoniacal gas over ignited charcoal contained in a tube ; as also by heating in a glass tube closed at one end, a mixture of oxalate of ammonia, and oxalate of manga- nese. Formiate of ammonia decomposed in a glass retort, is converted into hydrocyanic acid and water, One ten-thousandth part of prussic acid may be detected in water, by the addition of a few drops of solution of sulphate of iron. This test, although delicate, is surpassed by another, in which copper is used, and which will detect -j^.-fos of hydrocyanic acid in water. We must render the liquid containing the hydrocyanic acid, slightly alkaline with potash ; add a few drops of sulphate of cop- per, and afterwards sufficient muriatic acid to redissolve the excess of oxide of copper. The liquid will appear more or less milky, ac- cording to the quantity of hydrocyanic acid present. A cat was poisoned by twelve drops of hy- drocyanic acid, in sixty drops of water : the animal died one minute after having swallowed the poison. At the moment of its death, a vapour came from its throat smelling strongly of the acid, and a paper moistened with alkali, when held to it, was afterwards rendered blue by persulphate of iron. The animal was re- tained at the temperature of 50 F. for 18 hours, and then opened. The odour of prus- sic acid was readily perceived in* the brain, spinal marrow, and thoracic organs. It was but slightly perceptible in the stomach, which contained nothing but mucus ; but on cutting the organ in pieces, it was developed. The Stomach was cut into pieces under water, and distilled with the water. When about an eighth of the liquid had passed over, it was mixed with potash and persulphate of iron, and soon gave a feeble blue tint, leaving no doubt of the presence of hydrocyanic acid. The test by copper gave it still more sensibly. The copper tested prussic acid also in the in- testines ; but the persulphate of iron did not. Having been consulted by physicians and apothecaries concerning the strength of the dilute prussic or hydrocyanic acid employed in medicine, I instituted a series of experi- ments, to determine the relation between its specific gravity and quantity of real acid. The acid which I prepared with this view had a specific gravity = 0.957. The following table comprehends their results. Quantity of above Liquid Acid. Sp. Gravity. 50.0 0.9840 44.4 0.9870 40.0 0.9890 36.4 0.9900 33.3 0.9914 30.8 0.9923 28.6 0.9930 25.0 0.9940 22.2 0.9945 20.0 0.9952 18.2 0.9958 16.6 0.9964 15.4 0.9967 14.3 0.9970 13.3 0.1)973 12.5 0.9974 11.8 0.9975 10.5 0.9978 10.0 0.9979 Quantity of above Liquid Acid. 100.0 66.6 57-0 Sp. Gravity. 0.9570 0.9768 0.9815 Real Acid per cent. 16 10.6 9.1 Real Acid per cent. 8.0 7.3 6.4 5.8 5.3 5.0 4.6 4.0 3.6 3.2 3.0 2.7 2.5 2.3 2.1 2.0 1.77 1.68 1.60 From the preceding table it is obvious, that for acid of specific gravity 0.996 or 0-997, such as is usually prescribed in medicine, the density is a criterion of greater nicety than can be conveniently used by the majority of prac- titioners. In fact, the liquid at 0.996 contains about double the quantity of real acid, which it does at 0.998. It is therefore desirable to have another test of the strength of this power- ful and dangerous medicine, which shall be easier in use, and more delicate in its indica- tions. Such a test is afforded by the red oxide of mercury, the common red precipitate of the shops. The prime equivalent of prussic acid is exactly one-eighth of that of the mercurial peroxide. But as the prussiate of mercury consists of two primes of acid to one of base, or is, in its dry crystalline state, a bicyanide, we have the relation of one to four in the for- mation of that salt, when we act on the pe- roxide with cold prussic acid. Hence we derive the following simple rule of analysis. To 100 grains, or any other convenient quan- tity of the acid, contained in a small phial, add in succession small quantities of the per- oxide of mercury in fine powder, till it ceases to be dissolved on agitation. The weight of the red precipitate taken up being divided by four, gives a quotient representing the quan- tity of real prussic acid present. By weighing out beforehand, on a piece of paper, or a watch-glass, forty or fifty grains of the per- oxide, the residual weight of it shows at once the quantity expended. The operation may be always completed in five minutes, for the red precipitate dissolves as rapidly in the dilute prussic acid, with the aid of slight agitation, as sugar dissolves in water. Should the presence of muriatic acid be suspected, then the specific gravity of the liquid being compared with the numbers in the above table, and with the weight of perox- ide dissolved, will show how far the suspicion ACI 75 ACI is well founded. Thus, if 100 grains of acid, specific gravity 0.996, dissolve more than 12 grains of the red precipitate, _ we may be sure that the liquid has been contaminated with muriatic acid. Nitrate of silver, in common cases so valuable a reagent for mu- riatic acid, is unfortunately of little use here; for it gives with prussic acid a flocculent white precipitate, soluble in water of ammonia, and insoluble in nitric acid, which may be easily mistaken by common observers for the chlo- ride of that metal. But the difference in the volatility of prussiate and muriate of ammo- nia may be had recourse to with advantage; the former exhaling at a very gentle heat, the latter requiring a subliming temperature of about 300 Fahrenheit. After adding am- monia in slight excess to the prussic acid, if we evaporate to dryness at a heat of 212, we may infer from the residuary sal ammoniac the quantity of muriatic acid present. The preceding table is the result of experi- ments which I made some time ago at Glas- gow. I have lately verified its accuracy by experiments made at the Apothecaries' Hall, London, on their pure prussic acid. 100 grains of the bicyanide of mercury require for their conversion into bichloride (corrosive sublimate), 28.56 grains of chlorine, a quan- tity to be found in 100 grains of muriatic acid, specific gravity 1.1452. And as 100 grains of the bicyanide afford 20.6 of real prussic acid, they will furnish, by careful dis- tillation on a water bath, a quantity of liquid acid, equivalent to 700 grains of the medicinal strength 0.996. By consulting my table of muriatic acid, published in this Dictionary, the quantity of it at any density, necessary for decomposing the above cyanide, will be im- mediately found ; bearing in mind, that 31.5 = the prime equivalent of the salt, corresponds to 9 of chlorine. Scheele found that prussic acid occasioned precipitates with only the following three metallic solutions ; nitrates of silver, and mercury, and carbonate of silver. The first is white, the second black, the third green, becoming blue. The hydrocyanates are all alkaline, even when a great excess of acid is employed in their formation ; and they are decomposed by the weakest acids. The hydrocyanate of ammonia crystallizes in cubes, in small prisms crossing each other, or in feathery Crystals, like the leaves of a fern. Its volatility is such, that at the tem- perature of 7H it is capable of bearing a pressure of 17-72 inches of mercury; and at 97 its elasticity is equal to that of the atmo- sphere. Unfortunately this salt is charred and decomposed with extreme facility. Its great volatility prevented M. Gay Lussac from de- termining the proportion of its constituents. Hydrocyanic acid converts iron or its oxide into prussian blue without the help either of alkalis or acids. Cyanogen acts on iron and water as iodine does on water and a base ; and a CYANIC acid is formed, which dissolves a part of the iron, but also and at the same time hydrocyanic acid, which changes another part of the iron into prussian blue. According to M. Vauquelin, very complex changes take place when gaseous cyanogen is combined with water, which leave the nature of cyanic acid involved in some obscurity. The water is decomposed; part of its hydrogen combines with one part of the cyanogen, and forms hydrocyanic acid ; another part unites with the nitrogen of the cyanogen, and forms ammonia ; and the oxygen of the water forms carbonic acid, with one part of the carbon of the cyanogen. Hydrocyanate, carbonate, and cyan ate of ammonia, are also found in the liquid ; and there still remain some carbon and nitrogen, which produce a brown deposit. Four and a half parts of water absorb one of gaseous cyanogen, which communicate to it a sharp taste and smell, but no colour. The solution in the course of some days, however, becomes yellow, and afterwards brown, in consequence of the intestine changes related above. Hydrocyanic acid is separated from potash by carbonic acid ; but when oxide of iron is added to the potash, M. Gay Lussac conceives that a triple compound, united by a much more energetic affinity, results, constituting what is usually called prussiate of potash, or prussiate of potash and iron. In illustration of this view, he prepared a hydrocyanate of potash and silver, which was quite neutral, and which crystallized in hexagonal plates. The solution of these crystals precipitates salts of iron and copper, white. Muriate of am- monia does not render it turbid ; but muriatic acid, by disengaging hydrocyanic acid, preci- pitates chloride of silver. Sulphuretted hy- drogen produces in it an analogous change. This compound, says M. Gay Lussac, is evidently the triple hydrocyanate of potash and silver; and its formation ought to be analogous to that of the other triple hydro- cyanates. " And as we cannot doubt," adds he, " that hydrocyanate of potash and silver is in reality, from the mode of its formation, a compound of cyanide of silver and hydrocy- anate of potash, I conceive that the hydro- cyanate of potash and iron is likewise a com- pound of neutral hydrocyanate of potash, and subcyanide of iron, which I believe to be combined with hydrocyanic acid in the white precipitate. We may obtain it perfectly neutral, and then it does not decompose alum; but the hydrocyanate of potash, which is always alkaline, produces in it a light and flocculent precipitate of alumina. To the same excess of alkali we must ascribe the ochry colour of the precipitates which hydrocyanate of potash forms with the persalts of iron. Thus the remarkable fact, which ought to fix ACI ACI the attention of chemists, and which appears to me to overturn the theory of Mr. Porrett, is, that hydrocyanate of potash cannot become neutral except when combined with the cya- nides." ACID (CYANIC). Cyanate of potash may be procured in large quantity by heating to dull redness a very finely pulverized mix- ture of about equal parts of ferroprussiate of potash (well dried) and peroxide of manganese. If the heat be too great, we shall obtain little salt, because the deutoxide formed appears to change into protoxide at the expense of the cyanate. The mass is to be boded with al- cohol of moderate strength (0.840 sp. gr.), and on cooling, the salt separates in small plates, resembling chlorate of potash. It is insoluble in pure alcohol. Cyanate of potash acted on by muriatic acid gas is converted into chloride of potassium, and much sal ammoniac is developed. Cyanate of potash by simple boiling in water becomes carbonate of potash. By both modes of ana- lysis it seems to consist of potash 57-95, acid 42.05; whence the prime equivalent of the acid would seem to be 4. 45: 100 of cyanate of silver contain 77-353 of oxide ; a statement according nearly with the above equivalent. The cyanates acted on by aqueous acids, give out their carbon of composition in the form of carbonic acid. In this way, the acid constituent of cyanate of silver was analyzed, and found to contain, carbon 35.334, azote 41.317, and oxygen 23.349; or cyanogen 76.471, oxygen 23.529. In fact, 2 atoms of carbon =1.5 + 1, azote = 1.75 + 1, oxygen = 1. give a sum == 4.25; which converted to per cent, proportions are, carbon 35.3, azote 41.7, oxygen 23.53 = 100. Hence this acid has the same composition as the fulminic acid, though its properties are very different. F. W older, Annalcs de Chini. et de Phys, xxvii. 196. ACID (CHLOROCYANIC, or CHLO- ROPRUSSiC). M. Berthollet discovered, that when hydrocyanic acid is mixed with chlorine, it acquires new properties. Its odour is much increased. It no longer forms prus- sian blue with solutions of iron, but a green precipitate, which becomes blue by the addi- tion of sulphurous acid. Hydrocyanic acid thus altered had acquired the name of oxy- prussic, because it was supposed to have ac- quired oxygen. M. Gay Lussac subjected it to a minute examination, and found that it was a compound of equal volumes of chlorine and cyanogen, whence he proposed to distinguish it by the name of chlorocyanic acid. To pre- pare this compound, he passed a current of chlorine into solution of hydrocyanic acid, till it destroyed the colour of sulphate of indigo ; and by agitating the liquid with mercury, he deprived it of the excess of chlorine. By dis- tillation, afterwards, in a moderate heat, an elastic fluid is disengaged, which possesses the properties formerly assigned to oxyprmsic acid* This, however, is not pure chlorocyanic acid f but a mixture of it with carbonic acid, in pro- portions which vary so much, as to make it difficult to determine them. When hydrocyanic acid is supersaturated with chlorine, and the excess of this last is re- moved by mercury, the liquid contains chloro- cyanic and muriatic acids. Having put mer- cury into a glass jar until it was 3-4ths full, he filled it completely with that acid liquid, and inverted the jar in a vessel of mercury. On exhausting the receiver of an air-pump containing this vessel, the mercury sunk in the jar, in consequence of the elastic fluid dis- engaged. By degrees the liquid itself was en- tirely expelled, and swam on the mercury on the outside. On admitting the ah*, the liquid could not enter the tube, but only the mercury, and the whole elastic fluid condensed, except a small bubble. Hence it was concluded that chlorocyanic acid was not a permanent gas, and that, in order to remain gaseous under the pressure of the air, it must be mixed with another gaseous substance. The mixture of chlorocyanic and carbonic acids, has the following properties. It is co- lourless. Its smell is very strong. A very small quantity of it irritates the pituitory membrane, and occasions tears. It reddens litmus, is not inflammable, and does not de- tonate when mixed with twice its bulk of oxy- gen or hydrogen. Its density, determined by calculation, is 2. 1 1 ] . Its aqueous solution does not precipitate nitrate of silver, nor barytes water. The alkalis absorb it rapidly, but an excess of them is necessary to destroy its odour. If we then add an acid, a strong effervescence of carbonic acid is produced, and the odour of chlorocyanic acid is no longer perceived. If we add an excess of lime to the acid solution, ammonia is disengaged in abundance. To ob- tain the green precipitate from solution of iron, we must begin by mixing chlorocyanic acid with that solution. We then add a little pot- ash, and at last a little acid. If we add the alkali before the iron, we obtain no green pre- cipitate. M. Gay Lussac deduces for the composition of chlorocyanic acid 1 volume of carbon + a volume of azote + \ a volume of chlorine^ and when decomposed by the successive action of an alkali and an acid, it produces 1 volume of muriatic acid gas + 1 volume of carbonic acid + 1 volume of ammonia. The above three elements separately constituting two volumes, are condensed, by forming chloro- carbonic acid into one volume. And since one volume of chlorine, and one volume of cyanogen, produce two volumes of chloro- cyanic acid, the density of this last ought to be the half of the sum of the densities of its two constituents. Density of chlorine is 2.421, density of cyanogen 1.H01, half sum = 2.1 1 1, as stated above : Or the proportions by weight ACI ACI will be 3.25 = a prime equivalent of cyano- gen -f 4.5 = a prime of chlorine, giving the equivalent of chlorocyanic acid = 7-75. Chlorocyanic acid exhibits with potassium almost the same phenomena as cyanogen. The inflammation is equally slow, and the gas di- minishes as much in volume. ACID (FERROPRUSSIC). Into a so- lution of the amber-coloured crystals, usually called prussiate of potash, pour hydrosulphu- ret of barytes, as long as any precipitate falls. Throw the whole on a filter, and wash the pre- cipitate with cold water. Dry it ; and having dissolved 100 parts in cold water, add gradually 30 of concentrated sulphuric acid ; agitate the mixture, and set it aside to repose. The super- natant liquid is the ferroprussic acid of Mr. Porrett. It has a pale lemon-yellow colour, but no smell. Heat and light decompose it. Hydro- cyanic acid is then formed, and white ierro- prussiate of iron, which soon becomes blue. Its affinity for the bases enables it to displace acetic acid, without heat, from the acetates, and to form ferroprussiates. When a saline solution contains a base with which the ferroprussic acid forms an insoluble compound, then, agreeably to Berthollet's principle, it is capable of supplanting its acid. When ferroprussiate of soda is exposed to vol- taic electricity, the acid is evolved at the posi- tive pole, with its constituent iron. Mr. Por- rett considers this acid " as a compound of 4 atoms carbon = 30.00 1 atom azote = 17.50 1 atom iron = 17.50 1 atom hydrogen = 1.25 66.25" This sum represents the weight of its prime equivalent. Ferroprussiate of potash, and of barytes, will each, therefore, according to him, consist of an atom of acid -{- an atom of base -j- two atoms of water. Berzelius has shown that when sulphuretted hydrogen gas is transmitted over effloresced ferruginous prussiate of potash, heated in a glass tube by a spirit lamp, no hydrocyanic acid or water is produced ; and that therefore the iron present in the salt is in the metallic state. On igniting dry ferroprussiate of pot- ash along with peroxide of copper in a glass tube, the same chemist found that the gaseous products consisted of carbonic acid and azote in the proportion of three volumes of the former to two volumes of the latter. The same result was obtained from ferroprussiate of barytes. But as the potash and barytes of the above salts retain a portion of the carbonic acid, Ber- zelius next analyzed in the same way ferro- prussiate of lead : he found that the gas col- lected towards the end of the operation, which was quite free from atmospheric air, was a mixture of two parts of carbonic acid, and one part of azote by volume. Hence the carbon and azote in these salts exist in the same pro- portions as in cyanogen ; no water was pro- duced. He finally concludes, that the dry ferroprussiates are composed of one atom of cyanide of iron and two atoms of cyanide of the other metal, potassium, barium, or lead; ac- cording as it is a ferroprussiate of potash, ba- rytes, or lead, that is in question. Berzelius considers the ferroprussic or ferruretted chyazic acid of Mr. Porrett as a super-hydrocyanate of iron in an impure state. To obtain it pure he adopted the following method : he decom- posed well-washed ferroprussiate of lead, under water, by a current of sulphuretted hydrogen gas, removing the excess of sulphuretted hy- drogen with a small quantity of ferroprussiate of lead. The filtered fluid remained limpid and colourless in vacuo, leaving eventually a milk-white substance, which had no appear- ance of crystallization. This white matter has the following properties. It dissolves in water, to which it imparts an acid and agree- able flavour, but which is rather astringent. In contact with the air it deposits prussian blue, and assumes a greenish colour. It is inodorous, unless it has begun to decompose. When boiled, the liquid gives outjiydrocyanic acid, and deposits a powder which becomes blue in contact with the air. It is necessary to boil it for some time to decompose it en- tirely. If cold water be saturated with dry super-hydrocyanate, and the solution be suf- fered to remain, it gives small transparent co- lourless crystals, which appear to contain water of crystallization. The crystals are apparently quadrilateral prisms in groups composed of concentric rays. Berzelius supposes these to be hydrocyanate, in which water replaces the second base that existed with the protoxide of iron. The white substance obtained by eva- poration in vacuo does not appear to contain any water, or rather appears to be the super- hydrocyanate of protoxide of iron, without water of crystallization : for if it be distilled in a small and proper apparatus, it gives at first hydrocyanic acid; afterwards carbonate of am- monia and prussiate of ammonia. The pro- duction of ammonia in this experiment proves that what remains after the hydrocyanic acid, which is first evolved, is a hydrocyanate, and not a cyanide, because in the latter case it could only have given hydrocyanic acid and azotic gas. This substance may be kept with- out alteration in well closed vessels; but in the air it gradually decomposes, becomes at first greenish, afterwards blue, and finishes by being entirely converted into prussian blue. On the relations of prussic acid and iron, the following observations by M. Vauquelin are curious. Hydrocyanic acid diluted with water, when placed in contact with iron in a glass vessel standing over mercury, quickly produces prussian blue, while, at the same time, hydrogen gas is given out. The great- est part of the prussian blue formed in that ACI 78 ACI operation, remains in solution in the liquid. It appears only when the liquid comes in con- tact with the air. This shows us that prussian blue, at a minimum of oxidizement, is soluble in hydrocyanic acid. Dry hydrocyanic acid placed in contact with iron filings, undergoes no change in its colour nor smell ; but the iron, which becomes agglutinated together at the bottom of the vessel, assumes a brown colour. After some days, the hydrocyanic acid being separated from the iron, and put in a small capsule under a glass jar, evaporated without leaving any residue. Therefore it had dissolved no iron. Hydrocyanic acid dissolved in water, placed in contact with hydrate of iron, obtained by means of potash, and washed with boiling water, furnished prussian blue im- mediately, without the addition of any acid. Scheele has made mention of this fact. When hydrocyanic acid is in excess on the oxide of iron, the liquor which floats over the prussian blue assumes, after some time, a beautiful purple colour. The liquor, when evaporated, leaves upon the edge of the dish circles of blue, and others of a purple colour, and like- wise crystals of this last colour. When water is poured upon these substances, the purple- coloured body alone dissolves, and gives the liquid a fine purple colour. The substance which remains undissolved is prussian blue, which has been held in solution in the hydro- cyanic acid. Some drops of chlorine let fall into this liquid change it to blue, and a greater quantity destroys its colour entirely. It is remarkable that potash poured into the liquid thus deprived of its colour, occasions no pre- cipitate whatever. Chemists will not fail to remark, from these experiments, that hydrocyanic acid does not form prussian blue directly with iron; but that, on the addition of water, (circumstances remaining the same,) prussian blue is pro- duced. They will remark, likewise, that cya- nogen united to water dissolves iron. This is confirmed by ths inky taste which it acquires, by the disappearance of its colour, and by the residue which it leaves when evaporated ; yet prussian blue is not formed. These experi- ments seem to show that prussian blue is a hydrocyanate, and not a cyanide. The ammonia, and hydrocyanic acid, dis- engaged during the whole duration of the combustion of prussian blue, give a new sup- port to the opinion, that this substance is a hydrocyanate of iron ; and likewise the results which are furnished by the decomposition of prussian blue by heat in a retort, show clearly that it contains both oxygen and hydrogen, which are most abundant towards the end, long after any particles of adhering water must have been dissipated. Such compounds we shall call ferroprus- siates. M. Vauquelin and M. Thenard style them ferruginous prussiates. Ferroprussiatc of potash. Into an egg- shaped iron pot, brought to moderate ignitiony project a mixture of good pearl-ash and dry^ animal matters, of which hoofs and horns are best, in the proportion of two parts of the for- mer to five of the latter. Stir them well with a flat iron paddle. The mixture, as it calcines, will gradually assume a pasty form, during which transition it must be tossed about with much manual labour and dexterity. When the conversion into a chemical compound is seen to be completed by the cessation of the fetid animal vapours, remove the pasty mass with an iron ladle. If this be thrown, while hot, into water, some of the prussic acid will be converted into ammonia, and of course the usual product di- minished. Allow it to cool, dissolve it in water, clarify the solution by filtration or sub- sidence, evaporate, and, on cooling, yellow crystals of the ferroprussiate of potash will form. Separate these, redissolve them in hot water, and by allowing the solution to cool very slowly, larger and very regular crystals may be had. This salt is now manufactured in several parts of Great Britain, on the large scale ; and therefore the experimental chemist need not incur the trouble and nuisance of its prepara- tion. Nothing can exceed in beauty, purity, and perfection, the crystals of it prepared at Campsie, by Mr. Mackintosh. An extemporaneous ferroprussiate of potash may at any time be made, by acting on prus- sian blue with pure carbonate of potash, pre- pared from the ignited bicarbonate or bitartrate. The blue should be previously digested at a moderate heat, for an hour or two, in its own weight of sulphuric acid diluted with five times its weight of water ; then filtered, and thoroughly edulcorated by hot water, from the sulphuric acid. Of this purified prussian blue, add successive portions to the alkaline solution, as long as its colour is destroyed, or while it continues to change from blue to brown. Filter the liquid, saturate the slight alkaline excess with acetic acid, concentrate by evaporation, and allow it slowly to cool. Quadrangular bevelled crystals of the ferroprussiate of potash will form. This salt is transparent, and of a beautiful lemon or topaz-yellow. Its specific gravity is 1.830. It has a saline, cooling, but not unpleasant taste. In large crystals it pos- sesses a certain kind of toughness, and, in thin scales of elasticity. The inclination of the bevelled side to the plane of the crystal is about 135. It loses about 13 per cent, of water, when moderately heated; and then appears of a white colour, as happens to the green copperas ; but it does not melt like this salt. The crystals retain their figure till the heat verges on ignition. At a red heat it blackens, but, from the mode of its formation, we see that even that temperature is compatible with the existence of the acid, provided it be not too long continued. Water at 60 dis- AC I 79 ACI solves nearly one-third of its weight of the crystals ; and at the boiling point, almost its own weight. It is not soluble in alcohol; and hence, chemical compilers, with needless scrupulosity, have assigned to that liquid the hereditary sinecure of screening the salt from the imaginary danger of atmospherical action. It is not altered by the air. Exposed in a re- tort to a strong red heat, it yields prussic acid, ammonia, carbonic acid, and a coaly residue consisting of charcoal, metallic iron, and pot- ash. When dilute sulphuric or muriatic acid is boiled on it, prussic acid is evolved, and a very abundant white precipitate of proto- prussiate of iron and potash falls, which after- wards, treated with liquid chlorine, yields a prussian blue, equivalent to fully one-third of the salt employed. Neither sulphuretted hy- drogen, the hydrosulphurets, nor infusion of galls, produce any change on this salt. Red oxide of mercury acts powerfully on its solu- tion at a moderate heat. Prussiate of mercury is formed, which remains in solution ; while peroxide of iron and metallic mercury pre- cipitate. Thus we see that a portion of the mercurial oxide is reduced, to carry the iron to the maximum of oxidizement. The solution of ferroprussiate of potash is not affected by alkalis ; but it is decomposed by almost all the salts of the permanent metals. The following table presents a view of the colours of the metallic precipitates thus obtained. Solutions of Manganese, Protoxide of iron, Deutoxide of iron, Tritoxide of iron, Tin, Zinc, Antimony, Uranium, Cerium, Cobalt, Titanium, Bismuth, Protoxide of copper, Deutoxide of copper, Nickel, Lead, Deutoxide of mercury, Silver, Palladium, Rhodium, Platinum, and Gold, Give a White precipitate. Copious white. Copious clear blue. Copious dark blue. White. White. White. Blood-coloured. White. Grass-green. Green. White. White. Crimson-brown. Apple-green. White. White. White, passing to blue, in the air. Olive. None. If some of these precipitates, for example those of manganese or copper, be digested in a solution of potash, we obtain a ferroprussiate of potash and iron exactly similar to what is formed by the action of the alkaline solution on prussian blue. Those precipitates, there- fore, contain a quantity of iron. The researches of Berzelius have shown that dry ferroprussiate of potash is truly a compound of one atom of cyanide of iron, with two atoms of cyanide of potassium. Its composition may therefore be stated as follows : With water of cryst n . Iron = 3.50 15.05 13.15 2 atoms Potassium^: 10.00 43.00 37.56 Water 12.67 23.25 100.00 In its crystallized state it contains three atoms of water, which makes its prime equi- valent in that case 23. 25 + 3.375 = 26.625. To convert this weight into ferroprussiate of lead, two atoms of nitrate of lead will be re- quired 41.5 ; so that one atom of nitrate of lead = 20.75, will be equivalent to -- = 13.3125 of crystals of ferroprussiate of potash. These 13.3125 parts of salt, by the action of nitrate of lead, afford 12.75 parts of nitre, which contain six of potash. Ferroprussiate of soda may be prepared from prussian blue and pure soda, by a simi- lar process to that prescribed for the preceding salt. It crystallizes in four-sided prisms, ter- minated by dihedral summits. They are yellow, transparent, have a bitter taste, and effloresce, losing in a warm atmosphere 37 per cent. At 55 they are soluble in 4 parts of water, and in a much less quantity of boil- ing water. As the solution cools, crystals separate. Their specific gravity is 1.458. They are said by Dr. John to be soluble in alcohol. Its constituents are as follows : , , S Iron = 3.50 11.48 latom < Cyanogen^ 3.25 J 3197 9 atom* * Cyanogen 6.50 \ 2 atoms ^ Sodium _ ROQ Jg 67 10 atoms water 11.25 36.88 30.50 100.00 Ferroprussiate of lime may be easily formed from prussian blue and lime water. Its so- lution yields crystalline grains by evapora- tion. It consists of : Iron 3.50 1 1.86 Cyanogen 9.75 33.05 Calcium 5.00 16.96 Water 11.25 38.13 29.50 100.00 The preceding results, as also those of Berzelius on the ferrocyanide of lead being ap- parently discordant with those which I have stated in my paper, on the ultimate analysis of organic compounds (Phil. Trans. 1822), that a few words of explanation seem requisite. I found that an atom of nitrate of lead = ACI 80 ACI 20.75, was, by the method of double decom- position, equivalent to 13.125 of crystallized ferrocyanide of potassium ; whence I inferred that this was its atomic weight. According toBerzelius 20-75 parts of nitrate of lead, are equivalent to 13.3175 of the crystallized ferro- cyanide of potassium. This difference, though small, would excite my surprise, considering the pains that I took, did not Berzelius show that ferroprussiate of lead is apt to carry down in its precipitation, a portion of nitrate of that metal, to which circumstance I ascribe the above discrepancy. By my experiments, 13.3175 grains of the crystallized ferroprussiate of potash afford 5.9 of potash, a result not wide of the truth. From 21 grains of ferrocyanide of lead, I obtained 2.625 grains of peroxide of iron, = 1.8375 of metallic iron, while, by Berzelius, the quantity of iron present is 1.87, a difference onlyin the second place of decimals. But, with regard to my products of igneous decomposition by peroxide of copper, I am satisfied that a portion of the azote combined with the oxygen of the peroxide, into a liquid compound, whence the gaseous analysis was vitiated. 20-75 parts of nitrate of lead, con- taining 14 of oxide, or 13 of metal, should yield by Berzelius 19.625 of ferrocyanide of lead ; but I obtained 21, no doubt, in con- sequence of some nitrate falling down along with it From 13.125 grains of ferroprussiate of pot- ash I obtained 1.69 of water, which is 12.87 per cent. Berzelius obtained from 12.4 to 12.9, his calculated atomic proportion being 12.67. Had it occurred to me to double the above product 1.69, then the number 3.38, being as nearly as possible 3 atoms of water = 3.375, would have unravelled all the in- tricacy, and have satisfied me that the com- plex constitution assigned by Berzelius was the true one, since it gave the fewest integer atoms of the constituents. Ferroprussiate of barytes may be formed in the same way as the preceding species. Its crystals are rhomboidal prisms, of a yellow colour, and soluble in 2000 parts of cold water and 100 of boiling water. According to Berzelius ferroprussiate of barytes consists of Iron 3.500 . . 9.62 Cyanogen 9.750 . . 26.80 Barium 17-500 . . 48.11 Water 5.625 . . 15.47 36.375 100.00 Ferroprussiate of strontian and magnesia have also been made. Ferroprussiate of lead is formed by pouring neutral nitrate of lead into a solution of ferro- prussiate of potash, taking care that the latter be in excess, in order to prevent the precipita- tion of nitrate of lead, which mixes with all the insoluble salts with base of oxide of lead, if there be an excess of nitrate of lead in the liquid from which they are deposited. The liquid remains perfectly neutral. The pre- cipitate is white with a cast of yellow. Its composition is as follows : Iron 3.50 . . 8.92 Cyanogen 9-75 . . 24.84 Lead 26.00 . . 66.24 39.25 100.00 In its state of ordinary dryness it contains 3 atoms of water. Ferroprussiate of iron. We have already described the method of making the ferro- prussiate of potash, which is the first step in the manufacture of this beautiful pigment. This is usually made by mixing together one part of the ferroprussiate of potash, one part of copperas, and four parts of alum, each pre- viously dissolved in water. Prussian blue, mixed with more or less alumina, precipitates. It is afterwards dried on chalk stones, in a stove. Pure prussian blue is best prepared by dropping a solution of ferroprussiate of iron into a solution of red muriate of iron, to which a slight excess of acid is previously added. The precipitate must be thoroughly washed and dried. It retains hygrometric moisture so strongly, that sulphuric acid in vacuo does not detach it. Berzelius found that a portion of very dry prussian blue, when lighted at the edge, con- tinued to burn by itself like amadou, giving a vapour which condensed on a funnel inverted over it ; it was carbonate of ammonia. One hundred parts of such prussian blue left a re- sidium of 60.14 parts of red oxide of iron, containing no potash. When a solution of protoxide of iron is pre- cipitated by prussiate of iron and potash, a white insoluble compound is formed which contains potash, and which, by absorbing oxy- gen, becomes blue. But it is well known that a salt with base of protoxide, which, ab- sorbs oxygen without there being an increase of acid, combines with an excess of base. Prussian blue, therefore, which is prepared by oxidation of the white precipitate, cannot be a neutral compound. Prussian blue thus prepared, has properties which it does not pos- sess when differently prepared. It is soluble in pure water, but not in water which contains a certain quantity of any neutral salt. Thus there are evidently two blue combinations : The one composed of 3 atoms of hydrocyanate of protoxide, and 4 atoms of hydrocyanate of deutoxide, in which the acid and oxygen of the second part is double that of the first ; and another apparently composed of 1 atom of hydrocyanate of protoxide, and 2 atoms of hy- drocyanate of deutoxide. Ferroprussiate of ammonia is best prepared by acting on fcrroprussiateoflcad with caustic ACT 81 ACI ammonia. The solution being evaporated in vacua, a pulverulent salt is obtained. It is a hydrocyanate of protoxide of iron, combined with hydrocyanate of ammonia. Pure prussian blue is a mass of an ex- tremely deep blue colour, insipid, inodorous, and considerably denser than water. Neither water nor alcohol has any action on it Boil- ing solutions of potash, soda, lime, barytes, and strontites, decompose it ; forming on one hand soluble feroprussiates with these bases, and on the other a residue of brown peroxide of iron, and a yellowish-brown sub-ferroprus- siate of iron. This last, by means of sulphuric, nitric, or muriatic acids, is brought back to the state of a ferroprussiate, by abstracting the excess of iron oxide. Aqueous chlorine changes the blue to a green in a few minutes, if the blue be recently precipitated. Aqueous sulphuretted hydrogen reduces the blue ferro- prussiate to the white protofcrroprussiate. Its igneous decomposition in a retort was executed by M. Vauquelin with minute at- tention. He regards it as a hydrocyanate or mere prussiate of iron ; but the changes he describes are very complex. The general re- sults of M. Vauquelin's analysis were hydro- cyanic acid, hydrocyanate of ammonia, an oil soluble in potash, crystalline needles, which contained no hydrocyanic acid, but were merely carbonate of ammonia ; and finally, a ferreous residue slightly attracted by the mag- net, and containing a little undecomposed prus- sian blue. Proust, in the Annales de Chimie, vol. Ix. states, that 100 parts of prussian blue, with- out alum, yield 0.55 of red oxide of iron by combustion ; and by nitric acid, 0.54. 100 of prussiate of potash and iron, he further says, afford, after digestion with sulphuric or nitric acid, 35 parts of prussian blue. ACID (SULPHUROPRUSSIC); the sulphuretted chyazic acid of Mr. Porrett. Dissolve in water one part of sulphuret of potash, and boil it for a considerable time with three or four parts of powdered prussian blue added at intervals. Sulphuret of iron is formed, and a colourless liquid containing the new acid combined with potash, mixed with hyposulphate and sulphate of potash. Render this liquid sensibly sour, by the ad- dition of sulphuric acid. Continue the boiling for a little, and when it cools, add a little per- oxide of manganese in fine powder, which will give the liquid a fine crimson colour. To the filtered liquid add a solution contain- ing persulphate of copper, and protosulphate of iron, in the proportion of two of the former salt to three of the latter, until the crimson colour disappears. Sulphuroprussiate of cop- per falls. Boil this with a solution of potash, which will separate the copper. Distil the liquid mixed with sulphuric acid in a glass retort, and the peculiar acid will come over. By saturation with carbonate of barytes, and tlien throwing down this by the equivalent quantity of sulphuric acid, the sulphuroprussic acid is obtained pure. It is a transparent and colourless liquid, possessing a strong odour, somewhat resem- bling acetic acid. Its specific gravity is only 1.02*2. It dissolves a little sulphur at a boil- ing heat. It then blackens nitrate of silver ; but the pure acid throws down the silver white. By repeated distillations sulphur is separated and the acid is decomposed. Mr. Porrett, in the Annals of Phil, for May 1819, states the composition of this acid, as it exists in the sulphuretted chyazate of copper, to be 2 atoms sulphur, = 4.000 2 carbon, = 1.508 1 azote, = 1.754 1 hydrogen, =0.132 7-394 This is evidently an atom of the hydrocy- anic acid of M. Gay Lussac, combined with 2 of sulphur. If to the above we add 9 for an atom of protoxide of copper, we have 16.394 for the prime equivalent of the me- tallic salt. When cyanogen and sulphuretted hydrogen were mixed together by M. Gay Lussac in his researches on the prussic prin- ciple, he found them to condense into yellow acicular crystals. Mr. Porrett has since re- marked, that these crystals are not formed when the two gases are quite dry, but that they are quickly produced if a drop of water is passed up into the mixture. He does not think their solution in water corresponds to liquid sulphuretted chyazic acid ; it does not change the colour of litmus ; it has no effect on solutions of iron ; it contains neither prussic nor sulphuretted chyazic acid ; yet this acid is formed in it when it is mixed first with an alkali and then with an acid. The same treatment does not form any prussic acid. M. Gay Lussac states, that the yellow needles obtained from the joint action of cy- anogen and sulphuretted hydrogen, are " com- posed of one volume of cyanogen, and 1^ vo- lume of sulphuretted hydrogen." The Sulphuroprussiate of the red oxide of iron is a deliquescent salt, of a beautiful crim- son colour. It may be obtained in a solid form by an atmosphere artificially dried. Grotthus and Vogel, by fusing sulphur with ferroprussiate of potash, dissolving, filtering, and drying, obtained a substance which Ber- zelius has shown to be a sulphocyanide of po- tassium. Though he was not able to separate the sulphocyanogen, or sulphuret of cyanogen from the base, so as to have it in a separate state, yet he deduced its composition from experiments as being one atom of cyanogen, 3.25 -f- two atoms of sulphur, 4 =: 7-25. AC I ACI The sulphocyanide of potassium is com- posed of potassium one atom, 5 -}- sulpho- cyanogen one atom, 7-25 1 2.25. Sulphuretted hydrocyanic acid consists of one atom of hydrogen, 0.125 -j- one atom of sulphocyanogen 7.25 = 7-375. On substi- tuting selenium for sulphur, a selenio-cya- nide of potassium was formed, perfectly ana- logous to the sulphocyanide. Professor Zeise of Copenhagen describes (Ann. de Ch. et Phys. xxvi.) a new acid, and a new class of salts, produced by mixing in a wide-mouthed flask 16 measures of sulphu- ret of carbon with 45 measures of alcohol, and 100 measures of alcohol saturated with ammoniacal gas, at a temperature of 53 F. Two sets of crystals form. The first are finished in an hour or two, and have a feathery aspect. He considers them to be hydroxan- thate of ammonia. The formation of the second set of crystals takes 30 or 40 hours. These are distinctly grouped in stars, have considerable lustre, and a prismatic form. They are hydrosulphuretted hydrosulphocy- anate of ammonia. The flask or phial should be well closed with a ground stopper during the formation of these crystals, which are usually of a bright yellow colour. The salts of peroxide of copper produce, in the solution of that salt in water, a yellow flocculent pre- cipitate. This seems to be a compound of ordinary hydrosulphocyanic acid with bisul- phuret of copper. On dissolving 1 part of hydrosulphuretted hydrosulphocyanate of am- monia in about 180 of water, adding sul- phuric or muriatic acids diluted with 16 parts of water, till there be an acid excess, and then dropping into this mixture, in successive small portions, a solution of red oxide of iron in sulphuric or muriatic acid, the liquid be- comes a little dark and muddy, but it soon brightens up, with the formation in great abundance of crystalline white scales, which rapidly settle to the bottom. These crystals are to be taken out, and dried by pressure between folds of filtering paper. This matter contains no iron ; but is a peculiar compound of sulphur, carbon, azote, and hydrogen, to which M. Zeise gives the name of crystalline hydrosulphuret of cyanogen, composed pro- bably of 1 atom of azote, 2 of carbon, 4 of sulphur, and 2 of hydrogen. Hydrosulphu- retted hydrosulphocyanate of ammonia is re- presented as containing 1 atom ammonia, 2.125, 1 hydrosulphocyanic acid, 7-375, and 1 sul- phuretted hydrogen 2.125 = 11.625. ACID (PURPURIC). The excrements of the serpent Boa Constrictor consist of pure lithic acid. Dr. Prout found that on digest- ing this substance thus obtained, or from uri- nary calculi, in dilute nitric acid, an effer- vescence takes place, and the lithic acid is dissolved, forming a beautiful purple liquid. The excess of nitric acid being neutralized with ammonia, and the whole concentrated by slow evaporation, the colour of the solution becomes of a deeper purple ; and dark red granular crystals, sometimes of a greenish hue externally, soon begin to separate in abund- ance. These crystals are a compound of am- monia with the acid principle in question. The ammonia was displaced by digesting the salt in a solution of caustic potash, till the red colour entirely disappeared. This alkaline solution was then gradually dropped into di- lute sulphuric acid, which, uniting with the potash, left the acid principle in a state of purity. This acid principle is likewise produced from lithic acid by chlorine, and also, but with more difficulty, by iodine. Dr. Prout, the discoverer of this new acid, has, at the suggestion of Dr. Wollaston, called it pur- puric acid, because its saline compounds have for the most part a red or purple colour. This acid, as obtained by the preceding process, usually exists in the form of a very fine powder, of a slightly yellowish or cream colour ; and when examined with a magnifier, especially under water, appears to possess a pearly lustre. It has no smell, nor taste. Its spec. grav. is considerably above water. It is scarcely soluble in water. One-tenth of a grain, boiled for a considerable time in 1000 grains of water, was not entirely dissolved. The water, however, assumed a purple tint, probably, Dr. Prout thinks, from the forma- tion of a little purpurate of ammonia. Pur- puric acid is insoluble in alcohol and ether. The mineral acids dissolve it only when they are concentrated. It does not affect litmus paper. By igniting it in contact with oxide of copper, he determined its composition to be, 2 atoms hydrogen, 0.250 4.54 2 carbon, 1.500 - 27-27 2 oxygen, 2.000 - 36.36 1 azote, 1.750 - 31.81 5.50 99.98 Purpuric acid combines with the alkalis, al- kaline earths, and metallic oxides. It is ca- pable of expelling carbonic acid from the al- kaline carbonates by the assistance of heat, and does not combine with any other acid. These are circumstances sufficient, as Dr. Wollaston observed, to distinguish it from an oxide, and to establish its character as an acid. Purpurate of ammonia crystallizes in qua- drangular prisms, of a deep garnet-red colour. It is soluble in 1500 parts of water at 60, and in much less at the boiling temperature. The solution is of a beautiful deep carmine, or rose- red colour. It has a slightly sweetish taste, but no smell. Purpurate of potash is much more soluble ; that of soda is less ; that of lime is nearly insoluble: those of strontian and lime are slightly soluble. All the solu- tions have the characteristic colour. Purpurate ACl 8! of magnesia is very soluble ; and in solution, of a very beautiful colour. A solution of acetate of zinc produces with purpurate of ammonia a solution and precipitate of a beau- tiful gold-yellow colour ; and a most brilliant iridescent pellicle, in which green and yellow predominate, forms on the surface of the so- lution. Dr. Prout conceives the salts to be anhydrous, or void of water, and composed of two atoms of acid and one of base. The pur- puric acid and its compounds probably con- stitute the bases of many animal and vegetable colours. The well known pink sediment which generally appears in the urine of those labouring under febrile affections appears to owe its colour chiefly to the purpurate of am- monia, and perhaps occasionally to the pur- purate of soda. The solution of lithic acid in nitric acid stains the skin of a permanent colour, which becomes of a deep purple on exposure to the sun. These apparently sound experimental deductions of Dr. Prout have been called in question by M. Vauquelin ; but Dr. Prout ascribes M. Vauquelin's failure in attempt- ing to procure purpuric acid, to his having operated on an impure lithic acid. I think entire confidence may be put in Dr. Prout's experiments. He says that it is difficult to obtain purpuric acid from the lithic acid of urinary concretions Phil. Trans, for 1818, and Annals of Phil. vol. xiv. ACID (PYROCITRIC.) When citric acid is put to distil in a retort, it begins at first by melting ; the water of crystallization sepa- rates almost entirely from it by a continuance of the fusion, then it assumes a yellowish tint, which gradually deepens. At the same time there is disengaged a white vapour which goes over, to be condensed in the receiver. Towards the end of the calcination a brownish vapour is seen to form, and there remains in the bot- tom of the retort a light very brilliant char- coal. The product contained in the receiver con- sists of two different liquids. One, of an amber-yellow colour, and an oily aspect, oc- cupies the lower part ; another, colourless and liquid like water, of a very decided acid taste, floats above. After separating them from one another, we perceive that the first has a very strong bituminous odour, and an acid and acrid taste ; that it reddens powerfully the tincture of litmus, but that it may be deprived almost entirely of that acidity by agitation with water, in which it divides itself into globules, which soon fall to the bottom of the vessel, and are not long in uniting into one mass, in the man- ner of oils heavier than water. In this state it possesses some of the pro- perties of these substances ; it is soluble in alcohol, ether, and the caustic alkalis. How- ever, it does not long continue thus; it be- comes acid, and sometimes even it is observed to deposit, at the end of some days, white I ACI crystals, which have a very strong acidity ; if we then agitate it anew with water, it dissolves in a great measure^ and abandons a yellow or brownish pitchy matter, of a very obvious empyreumatic smell, and which has much analogy with the oil obtained in the distillation of other vegetable matters. The same effect takes place when we keep it under water ; it diminishes gradually in volume, the water ac- quires a sour taste, and a thick oil remains at the bottom of the vessel. This liquid may be regarded as a combina- tion (of little permanence indeed) of the pe- culiar acid with the oil formed in similar circum stances. As to the liquid and colourless portion which floated over this oil, it was ascertained to contain no citric acid carried over, nor acetic acid; first, because on saturating it with carbonate of lime, a soluble calcareous salt was obtained ; and, secondly, because this salt, treated with sulphuric acid, evolved no odour of acetic acid. From this calcareous salt the lime was se- parated by oxalic acid ; or the salt itself was decomposed with acetate of lead, and the pre- cipitate treated with sulphuretted hydrogen. By these two processes, this new acid was separated in a state of purity. Properties of the pyrocitric acid. This acid is white, inodorous, of a strongly acid taste. It is difficult to make it crystallize in a regular manner, but it is usually presented in a white mass, formed by the interlacement of very fine small needles. Projected on a hot body it melts, is converted into white very pungent vapours, and leaves some traces of carbon. When heated in a retort, it affords an oily-looking acid, and yellowish liquid, and is partially decomposed. It is very soluble in water and in alcohol ; water at the tem- perature of 10 C. (50 F.) dissolves one-third of its weight. The watery solution has a strongly acid taste, it does not precipitate lime or barytes water, nor the greater part of metallic solutions, with the exception of ace- tate of lead and protonitrate of mercury. With the oxides it forms salts possessing properties different from the citrates. The pyrocitrate of potash crystallizes in small needles, which are white, and unalter- able in the air. It dissolves in about 4 parts of water. Its solution gives no precipitate with the nitrate of silver, or of barytes ; whilst that of the citrate of barytes forms precipitates with these salts. The pyrocitrate of lime directly formed, ex- hibits a white crystalline mass, composed of needles, opposed to each other, in a ramifica- tion form. This salt has a sharp taste. It dissolves in 25 parts of water at 50 Fahr. It contains 30 per cent, of water of crystalli- zation ; and is composed, in its dry state, of Pyrocitric acid, 34 Lime, 66 ACI ACI The solution of the pyrocitric acid saturated With barytes water lets fall, at the end of some hours, a very white crystalline powder, which is pyrocitrate of barytes. This salt is soluble in 150 parts of cold water, and in 50 of boiling water. Two grammes of this salt de- composed by sulphuric acid, furnished 1.7 of sulphate of barytes, which gives for its com- position, Pyrocitric acid, 43.9 Barytes, 56.1 The pyrocitrate of lead is easily obtained by pouring pyrocitrate of potash into a solu- tion of acetate of lead. The pyrocitrate of lead presents itself under the form of a white gelatinous semitransparent mass, which be- comes dry in the air, shrinking like gelatinous alumina, to which, in its physical characters, it has much analogy. It contains 8 per cent. of water, and is formed of Pyrocitric acid, 33.4 Protoxide of lead, 66.6 Knowing the composition of pyrocitrate of lead, it was employed, by ignition with oxide of copper, to determine that of the acid itself, which is stated as being Carbon, 47.5 Oxygen, 43.5 Hydrogen, 9.0 100.0 The proportion of the elements of this acid is very different then from that which MM. Gay Lussac, Thenard, and Berzelius have found for citric acid. But what is remark- able, says M. Lassaigne, its capacity for satu- ration is nearly the same as that of citric acid, as we may see by casting our eyes on the analyses of the pyrocitrates of lime, barytes, and lead, which we have given, and which we have convinced ourselves of by frequent veri- fication. Nevertheless, in the combination of this new acid, the ratio of the oxygen of the oxide to the oxygen of the acid is in a dif- ferent proportion from that admitted for the neutral citrates : we observe that in the pyro- citrates the oxygen of the base is to that of the acid as 1 to 3.07 ; whilst in the citrates it is as 1 to 4.91 6. The author seems here to have miscalculated strangely. Taking his analysis of pyrocitrate of lime and of pyrocitric acid, we have 34 acid, which contain 14.6 of oxygen, 66 lime, - 18.6 of oxygen ; so that the oxygen of the base is to that of the acid as 1 to 0-785, instead of 1 to 3.07. In fact, the pyrocitrate of lime result makes the atom of acid, referred to Dr. Wollaston's scale, to be 18.3; that for pyrocitrate of ba- rytes makes it 76.5, and that for pyrocitrate of lead, 70. The only supposition we can form is, that the numbers for the calcareous salt are inverted in the Journal de Pharmacie , and that they ought to be, Pyrocitric acid, 66 Lime, 34 In this case the atom comes out 69.0; a tolerable accordance with the above. Were the equivalent of the acid 66.25, then it might consist of Carbon, 4 atoms = 30.00 45.27 Oxygen, 3 - = 30.00 45.27 Hydrogen, 5 - =6.25 9.46 66.25 100.00 ACID (PYROLIGNOUS). In the de- structive distillation of any kind of wood, an acid is obtained, which was formerly called acid spirit of -wood, and since, pyrolignous acid. Fourcroy and Vauquelin showed that this acid was merely the acetic, contaminated with empyreumatic oil and bitumen. See ACETIC ACID. Under acetic acid will be found a full ac- count of the production and purification of pyrolignous acid. M. Monge discovered, about five years ago, that this acid has the property of preventing the decomposition of animal substances. But I have lately learned that Mr. William Diusdale, of Field' Cottage,, Colchester, three years prior to the date of M. Monge's discovery, did propose to the Lords Commissioners of the Admiralty, to apply a pyrolignous acid, (prepared out of the contact of iron vessels, which blacken it), to the purpose of preserving animal food, wherever their ships might go. As this application may in many cases afford valuable anti-scorbutic articles of food, and thence be eminently conducive to- the health of seamen, it is to be hoped that their lordships will, ere long, carry into, effect Mr. Dinsdale's ingenious plan, as far as shall be deemed necessary. It is sufficient to. plunge meat for a few moments into this acid, even slightly empyreumatic, to preserve it as a as you please. " Putrefaction," it is j " not only stops, but retrogrades." To the empyreumatic oil a part of this effect has been ascribed ; and hence has been accounted for, the agency of smoke in the preservation of tongues, hams, herrings, &c. Dr. Jorg of Leipsic has entirely recovered several ana- tomical preparations from incipient corrup- tion by pouring this acid over them. With the empyreumatic oil or tar he has smeared pieces of flesh already advanced in decay, and notwithstanding that the weather was hot, they soon became dry and sound. To the above statements Mr. Ravnsay of Glasgow, an eminent manufacturer of pyrolignous acid, and well known for the purity of his vinegar from wood, has recently added the following facts in the 5th number of the Edinburgh. Philosophical Journal. If fish be simply dipped in redistilled pyrolignous acid, of the specific gravity 1.012, and afterwards dried in ACI 85 ACI the shade, they preserve perfectly well. On boil- ing herrings treated in this manner, they were very agreeable to the taste, and had nothing of the disagreeable empyreuma which those of his earlier experiments had, which were steeped for three hours in the acid. A num- ber of very fine haddocks were cleaned, split, and slightly sprinkled with salt for six hours. After being drained, they were dipped for about three seconds in pyrolignous acid, then hung up in the shade for six days. On being broiled, the fish were of an uncommonly fine flavour, and delicately white. Beef treated in the same way had the same flavour as Ham- burgh beef, and kept as well. Mr. Ramsay has since found, that his perfectly purified vinegar, specific gravity 1.034, being applied by a cloth or sponge to the surface of fresh meat, makes it keep sweet and sound for se- veral days longer in summer than it otherwise would. Immersion for a minute in his purified common vinegar, specific gravity 1.009, pro- tects beef and fish from all taint in summer, provided they be hung up and dried in the shade. When, by frequent use, the pyrolignous acid has become impure, it may be clarified by beating up twenty gallons of it with a dozen of eggs in the usual manner, and heating the mixture in an iron boiler. Before boiling, the eggs coagulate, and bring the impurities to the surface of the boiler, which are of course to be carefully skimmed off. The acid must be immediately withdrawn from the boiler, as it acts on iron. ACID (PYROLITHIC). When uric acid concretions are distilled in a retort, silvery white plates sublime. These are pyrolithate of ammonia. When their solution is poured into that of subacetate of lead, a pyrolithate of lead falls, which, after proper washing, is to be shaken with water, and decomposed by sulphuretted hydrogen gas. The superna- tant liquid is now a solution of pyrolithic acid, which yields small acicular crystals by evaporation. By heat, these melt and su- blime in white needles. They are soluble in four parts of cold water, and the solution reddens vegetable blues. Boiling alcohol dissolves the acid, but on cooling it deposits it, in small white grains. Nitric acid dis- solves without changing it. Hence, pyro- lithic is a different acid from the lithic, which, by nitric acid, is convertible into purpurate of ammonia. The pyrolithate of lime crys- tallizes in stalactites, which have a bitter and slightly acrid taste. It consists of 91.4 acid + 8.6 lime. Pyrolithate of barytes is a nearly insoluble powder. The salts of potash, soda, and ammonia, are soluble, and the former two crystallizable. At a red heat, and by passing it over ignited oxide of copper, it is decomposed, into oxygen 44.32, carbon 28.29, azote 1(5.84, hydrogen 10. ACID (PYROMALIC). When malic or sorbic acid, for they are the same, is dis- tilled in a retort, an acid sublimate, in white needles, appears i* the neck of the retort, and an acid liquid distils into the icceiver. This liquid, by evaporation, affords crystals, con- stituting a peculiar acid, to which the above name has been given. They are permanent in the air, melt at 118 Fahr., and on cooling form a pearl- coloured mass of diverging needles. When thrown on red-hot coals, they completely evaporate in an acrid, cough-exciting smoke. Exposed to a strong heat in a retort, they are partly sublimed in needles, and are partly de- composed. They are very soluble in strong alcohol, and in double their weight of water, at the ordinary temperature. The solution reddens vegetable blues, and yields white flocculent precipitates with acetate of lead and nitrate of mercury ; but produces no pre- cipitate with lime water. By mixing it with barytes water, a white powder falls, which is redissolved by dilution with water, after which, by gentle evaporation, the pyromalate of barytes may be obtained in silvery plates. These consist of 100 acid, and 185.142 barytes, or in prime equivalents, of 5.25 + 9-75. Pyromalate of potash may be obtained in feather-formed crystals, which deliquesce. Pyromalate of lead forms first a white floccu- lent precipitate, soon passing into a semi- transparent jelly, which, by dilution and fil- tration from the water, yields brilliant pearly- looking needles. The white crystals, that sublime in the original distillation, are con- sidered by M. Lassaigne as a peculiar acid. ACID (PYROMUCIC). This acid, dis- covered in 1818 by M. Houton Labillardiere, is one of the products of the distillation of mucic acid. When we wish to procure it, the operation must be performed in a glass retort furnished with a receiver. The acid is formed in the brown liquid, which is pro- duced along with it, and which contains water, acetic acid, and empyreumatic oil; a very small quantity of the pyromucic acid remaining attached to the vault of the retort, under the form of crystals. These crystals being coloured are added to the brown li- quor, which is then diluted with 3 or 4 times its quantity of water, in order to throw down a certain portion of oil. The whole is next filtered, and evaporated to a suitable degree. A great deal of acetic acid is volatilized, and then the new acid crystallizes. On decant- ing the mother waters, and concentrating them farther, they yield crystals anew ; but as these are small and yellowish, it is neces- sary to make them undergo a second distilla- tion to render them susceptible of being per- fectly purified by crystallization. 150 parts of mucic acid furnish about 60 of brown liquor, from which we can obtain 8 to 10 of pure pyromucic acid. This acid is white, inodorous, of a strongly ACI 86 ACI acid taste, and a decided action on litmus. Exposed to heat in a retort it melts at the temperature of 266 F., then volatilizes, and condenses into a liquid, which passes on cool- ing into a crystalline mass, covered with very fine needles. It leaves very slight traces of residuum in the bottom of the retort. On burning coals, it instantly diffuses white pungent vapours. Air has no action on it. Water at 60 dissolves Jg- of its weight. Boiling water dissolves it much more abundantly, and on cooling abandons a portion of it, in small elongated plates, which cross in every direction. Subacetate of lead is the only salt of whose oxide it throws down a portion. It consists in 100 parts of Carbon, Oxygen, Hydrogen, 52.118 45.806 2.111 This acid unites readily to the salifiable bases, and forms, With potash, a salt very soluble in water and alcohol, deliquescent, and which, evapo- rated to a pellicle, congeals into a granular mass; With soda, a salt less deliquescent and less soluble in water and alcohol than the pre- ceding ; but which crystallizes with difficulty ; With larytes, strontlan, and lime, salts soluble in water, and a little more so in hot than in cold, insoluble in alcohol, and easily obtained in crystals, which are permanent in the air ; With ammonia, a salt soluble in water, which, by evaporation of the liquid, loses a portion of its base, becomes acid, and then crystallizes with facility ; With protoxide of lead, a neutral soluble salt, which possesses remarkable properties. This salt is obtained by putting liquid pyro- mucic acid in contact with moist carbonate of lead. When we evaporate the solution, the salt collects at the surface in transparent liquid globules, of a brownish colour, and an oily aspect; which a little after they are removed assume the softness and toughness of pitch, and finally become solid, opaque, and whitish. This property belongs also to suc- cinate of lead. The alkaline pyromucates occasion scarcely any turbidity in the solutions of the metallic salts, if we except those of the peroxide of iron, of the peroxide of mercury, the sub- acetate of lead, and the protonitrate of tin. The deposit formed in the salts of iron is a yellow similar to that of turbeth mineral. In all the salts in the neutral state, the quantity of oxygen in the oxide is to the quantity in the acid as 1 to 13, which num- ber therefore represents the equivalent weight of pyromucic acid. Annales de Chim. et de /*. ix. 365. >> ACID (PYROTARTARIC). Into a coated glass retort introduce tartar, or rather tartaric acid, till it is half full, and fit to it a tubulated receiver. Apply heat, which is to be gradually raised to redness. Pyrotartaric acid of a brown colour, from impurity, is found in the liquid products. We must filter these through paper previously wetted, to se- parate the oily matter. Saturate the liquid with carbonate of potash ; evaporate to dry- ness; redissolve, and filter through clean moistened paper. By repeating this process of evaporation, solution, and filtration, several times, we succeed in separating all the oil. The dry salt is then to be treated in a glass retort, at a moderate heat, with dilute sul- phuric acid. There passes over into the re- ceiver, first of all a liquor containing evi- dently acetic acid ; but towards the end of the distillation, there is condensed, in the vault of the retort, a white and foliated sublimate, which is the pyrotartaric acid, per- fectly pure. It has a very sour taste, and reddens powerfully the tincture of'turnsole. Heated in an open vessel, the acid rises in a white smoke, without leaving the charcoaly resi- duum which is left in a retort. It is very soluble in water, from which it is separated in crystals by spontaneous evaporation. The bases combine with it, forming pyrotaitrates, of which those of potash, soda, ammonia, barytes, strontites, and lime, are very soluble. That of potash is deliquescent, soluble in al- cohol, capable of crystallizing in plates, like the acetate of potash. This pyrotartrate precipitates both acetate of lead and nitrate of mercury, whilst the acid itself precipitates only the latter. Rose is the discoverer of this acid, which was formerly confounded with the acetic. ACID (ROSASIC). There is deposited from the urine of persons labouring under intermittent and nervous fevers, a sediment of a rose colour, occasionally in reddish crys- tals. This was first discovered to be a pecu- liar acid by M. Proust, and afterwards ex- amined by M. Vauquelin. This acid is solid, of a lively cinnabar hue, without smell, with a faint taste, but reddening litmus very sen- sibly. On burning coal it is decomposed into a pungent vapour, which has not the odour of burning animal matter. It is very soluble in water, and it even softens in the air. It is soluble in alcohol. It forms solu- ble salts with potash, soda, ammonia, barytes, strontites, and lime. It gives a slight rose- coloured precipitate with acetate of lead. It also combines with lithic acid, forming so in- timate a union, that the lithic acid in preci- pitating from urine carries the other, though a deliquescent substance, down along with it. It is obtained pure by acting on the sedi- ment of urine with alcohol. See ACID (PuR- FURIC.) AC I 87 ACI ACID (SACLACTIC). See ACID (Mu- cic). ACID (SEBACIC). Subject to a con- siderable heat 7 or 8 pounds of hog's lard, in a stoneware retort capable of holding double the quantity, and connect its beak by an adopter with a cooled receiver. The con- densible products are chiefly fat, altered by the fire, mixed with a little acetic and sebacic acids. Treat this product with boiling water several times, agitating the liquor, allowing it to cool, and decanting each time. Pour at last into the watery liquid, solution of acetate of lead in excess. A white flocculent preci- pitate of sebate of lead will instantly fall, which must be collected on a filter, washed and dried. Put the sebate of lead into a phial, and pour upon it its own weight of sulphuric acid, diluted with five or six times its weight of water. Expose this phial to a heat of about 212. The sulphuric acid combines with the oxide of lead, and sets the sebacic acid at liberty. Filter the whole while hot. As the liquid cools, the sebacic acid crystallizes, which must be washed, to free it completely from the adhering sulphuric acid. Let it be then dried at a gentle heat. The sebacic acid is inodorous ; its taste is slight, but it perceptibly reddens litmus pa- per ; its specific gravity is above that of water, and its crystals are small white needles of little coherence. Exposed to heat, it melts like fat, is decomposed, and partially evapo- rated. The air has no effect vipon it. It is much more soluble in hot than in cold water ; hence boiling water saturated with it assumes a nearly solid consistence on cooling. Alco- hol dissolves it abundantly at the ordinary temperature. With the alkalis it forms soluble neutral salts ; but if we pour into their concentrated solutions, sulphuric, nitric, or muriatic acids, the sebacic is immediately deposited in large quantity. It affords precipitates with the acetates and nitrates of lead, mercury, and silver. Such is the account given by M. Thenard of this acid, in the 3d volume of his Traite de Chimie, published in 1815. Berzelius, in 1816, published an elaborate dissertation, to prove that M. Thenard' s new sebacic acid was only the benzoic, contaminated by the fat, from which, however, it may be freed, and brought to the state of common benzoic acid. M. Thenard takes no notice of M. Berzelius whatever, but concludes his account by stating, that it has been known only for twelve or thir- teen years, and that it must not be confounded with the acid formerly called sebacic, which possesses a strong disgusting odour, and was merely acetic or muriatic acid; or fat which had been changed in some way or other; ac- cording to the process used in the preparation. ACID (SELENIC). See SELENIUM. ACID (SILICATED FLUORIC). See ACID (FLUORIC). ACID (SORBIC). The acid of apples called malic, may be obtained most conve- niently and in greatest purity from the berries of the mountain ash, called sorbus or pyrus aucuparia, and hence the present name, sorbic acid. This was supposed to be a new and peculiar acid by Mr. Donovan and M. Vau- quelin, who wrote good dissertations upon it. But it now appears that the sorbic and pure malic acids are identical. Bruise the ripe berries in a mortar, and then squeeze them in a linen bag. They yield nearly half their weight of juice, of the specific gravity of 1.077- This viscid juice, by remaining for about a fortnight in a warm temperature, experiences the vinous ferment- ation, and would yield a portion of alcohol. By this change, it has become bright, clear, and passes easily through the filter, while the sorbic acid itself is not altered. Mix the clear juice with filtered solution of acetate of lead. Separate the precipitate on a filter, and wash it with cold water. A large quantity of boiling water is then to be poured upon the filter, and allowed to drain into glass jars. At the end of some hours, the solution deposits crystals of great lustre and beauty. Wash these with cold water, dissolve them in boiling water, filter, and crystallize. Collect the new crystals, and boil them for half an hour in 2.3 times their weight of sulphuric acid, specific gravity 1.090, supplying water as fast as it evaporates, and stirring the mixture diligently with a glass rod. The clear liquor is to be decanted into a tall narrow glass jar, and while still hot, a stream of sulphuretted hy- drogen is to be passed through it. When the lead has been all thrown down in a sulphuret, the liquid is to be filtered, and then boiled in an open vessel to dissipate the adhering sul- phuretted hydrogen. It is now a solution of sorbic acid. When it is evaporated to the consistence of a syrup, it forms mammelated masses of a crystalline structure. It still contains a con- siderable quantity of water, and deliquesces when exposed to the air. Its solution is trans- parent, colourless, void of smell, but power- fully acid to the taste. Lime and barytes waters are not precipitated by solution of the sorbic acid, although the sorbate of lime is nearly insoluble. One of the most charac- teristic properties of this acid is the precipitate which it gives with the acetate of lead, which is at first white and flocculent, but afterwards assumes a brilliant crystalline, appearance. With potash, soda, and ammonia, it forms crystallizable salts containing an excess of acid. That of potash is deliquescent. Sorbate of barytes consists, according to M. Vauquelin, of 47 sorbic acid, and 53 barytes in 100. Sorbate of lime well dried, appeared to be ACI 88 ACI composed of G7 acid -f 33 lime = 100. Sorbate of lead, which in solution, like most of the other sorbates, retains an acidulous taste, consists in the dried- state of 33 acid -f- 67 oxide of lead in 100. The ordinary sor- bate contains 12.5 per cent, of water. M. Vauquelin says that Mr. Donovan was mis- taken in supposing that he had obtained super and subsorbates of lead. There is only one salt with this base, according to M. Vau- quelin. It is nearly insoluble in cold water ; but a little more so in boiling water: as it cools it crystallizes in the beautiful white, brilliant, and shining needles, of which we have already spoken. A remarkable pheno- menon occurs, when sorbate of lead is boiled in water. Whilst one part of the salt saturates the water, the other part, for want of a suffi- cient quantity of fluid to dissolve it, is par- tially melted, and is at first kept on the surface by the force of ebullition, but after some time falls to the bottom, and as it cools becomes strongly fixed to the vessel. To procure sorbic acid, M. Braconnot sa- turates with chalk the juice of the scarcely ripe berries, evaporates to the consistence of a syrup, removing the froth ; and a granular sorbate falls, which he decomposes by car- bonate of soda. The sorbate of soda is freed from colouring matter by a little lime, strained, freed from lime by carbonic acid gas, and decomposed by subacetate of lead, and treated as above. M. Vauquelin analyzed the acid, in the dry sorbates of copper and lead. The following are its constituents : Hydrogen, 16.8 Carbon, ' 28.3 Oxygen, 54.9 100.0 M. Vauquelin' s analysis of the sorbate of lead gives 70 for the prime equivalent of this acid ; the sorbate of lime gives 7-230 ; and the sorbate of barytes 8.6- If we take that of lime for the standard, as it was the only one quite neutral, we shall have the following re- lation of prime equivalents : Theory. Experiment. 4 of oxygen = 4.00 53.3 54.9 3 of carbon = 2.25 30.0 28.3 10 of hydrogen = 1.25 16-7 16.8 7.50 100.0 100.0 Th^ approximation of these sets of propor- tions illustrates and confirms the accuracy of M. Vauquelin's researches. The calcareous salt having been procured in a neutral state, by the addition of carbonate of potash to its acidulous solution, it might readily be mixed with as much carbonate of lime as would diminish the apparent equiva- lent of acid from 7'50 to 7.230 ; especially as the barytic compound gives no less than 8.6. Had the composition of the sorbate of lime been 67-7 and 32.3, instead of 67 and 33, the prime equivalent of the acid would come out 7-5, as its ultimate analysis indicates. As the pure sorbic acid appears to be with- out odour, without colour, and of an agreeable taste, it might be substituted for the tartaric and citric, in medicine and the arts. The same acid may be got from apples, in a similar way. ACID (STIBIC). See ACID (ANTI- MONIC). ACID (STIBIOUS). See ACID (A- TIMONIOUS). ACID (SUBERIC). M. Chevreul ob- tained the suberic acid by mere digestion of the nitric acid on grated cork, without distil- lation, and purified it by washing with cold water. 12 parts of cork may be made to yield one of acid. When pure, it is white and pulverulent, having a feeble taste, and little action on litmus. It is soluble in 80 parts of water at 55^ F. and in 38 parts at 140. It is much more soluble in alcohol, from which water throws down a portion of the suberic acid. It occasions a white precipitate when poured into acetate of lead, nitrates of lead, mercMry, and silver, muriate of tin, and pro- tosulphate of iron. It affords no precipitate with solutions of copper or zinc. The sube- rates of potash, soda, and ammonia, are very soluble. The two latter may be readily crys- tallized. Those of barytes, lime, magnesia, and alumina, are of sparing solubility. ACID (SUCCINIC). It has long been known that amber, when exposed to distilla- tion, affords a crystallized substance, which sublimes into the upper part of the vessel. M. Julin, of Abo, states, that by mixing with coarsely powdered amber ^ part of sul- phuric acid, diluted with an equal weight of water, the succinic acid will be produced in about twice the quantity got in the old way. Several processes have been proposed for purifying this acid : that of Richter appears to be the best. The acid being dissolved in hot water, and filtered, is to be saturated with potash or soda, and boiled with charcoal, which absorbs the oily matter. The solution being filtered, nitrate of lead is added ; whence results an insoluble succinate of lead, from which, by digestion in the equivalent quantity of sulphuric acid, pure succinic acid is sepa- rated. Nitrate or muriate of barytes will show whether any sulphuric acid remains mixed with the succinic solution ; and if so, it may be withdrawn by digesting the liquid with a little more succinate of lead. Pure succinic acid may be obtained by evaporation, in white transparent prismatic crystals. Their taste is somewhat sharp, and they redden powerfully tincture of turnsole. Heat melts and partially decomposes succinic acid. Air has no effect ACI ACI upon it. It is soluble in both water and alcohol, and much more so when they are heated. Its prime equivalent, by Berzelius, is 6.2G ; and it is composed of 4.51 hydrogen, 47.6 carbon, 47-888 oxygen, in 100, or 2 + 4+3 primes. With barytes and lime the succinic acid forms salts but little soluble ; and with mag- nesia it unites into a thick gummy substance. The succinates of potash and ammonia are cry s- tallizable and deliquescent ; that of soda does not attract moisture. The succinate of ammonia is useful in analysis to separate oxide of iron. ACID (SULPHOVINIC). The name given by Vogel to an acid, or class of acids, which may be obtained by digesting alcohol and sulphuric acid together with heat. ACID (SULPHURIC). Sulphuric acid was formerly obtained in this country by dis- tillation from sulphate of iron, as it still is in many parts abroad. The fluid that is thus obtained is the German sulphuric acid, of which Bernhardt got sixty-four pounds from six hundred weight of vitriol ; and on the other hand, when no water had been pre- viously poured into the receiver, fifty-two pounds only of a dry concrete acid. This acid was formerly called glacial oil of vitriol. It was shown by Vogel, that when this fuming acid is put into a glass retort, and distilled by a moderate heat into a receiver cooled with ice, the fuming portion comes over first, and may be obtained in a solid state by stopping the distillation in time. This constitutes absolute sulphuric acid, or acid entirely void of water. It is in silky filaments, tough, difficult to cut, and somewhat like asbestos. Exposed to the air, it fumes strongly, and gradually evaporates. It does not act on the skin so rapidly as concentrated oil of vitriol. Up to 66 it continues solid, but at temperatures above this it becomes a colourless vapour, which whitens on contact with air. Dropped into water in small quan- tities, it excites a hissing noise, as if it were red-hot iron ; in larger quantities it produces a species of explosion. It is convertible into ordinary sulphuric acid, by the addition of water. It dissolves sulphur, and assumes a blue, green, or brown colour, according to the proportion of sulphur dissolved. The specific gravity of the black fuming sulphuric acid, prepared in large quantities from copperas, at Nordhausen, is 1.896. The ordinary liquid acid of Nordhausen is brown, of variable density, and boils at 100 or 120 F. One part of it evaporates in dense fumes, and the remainder is found to be com- mon oil of vitriol. The above solid anhydrous acid has a specific gravity of 1.9? at 68 F.; at 77-0 it remains fluid, and is less viscid than oil of vitriol. There is a little sulphurous acid present in that of Nordhausen, but it is acci- dental, and not essential to its constitution. The anhydrous acid makes a red solution of indigo. In the Journal of Science, xix. 62, I published the result of some experiments which I made to determine the nature of the solid acid. The brown liquid acid had a specific gravity of 1.842. When distilled from a retort into a globe surrounded with ice, a white solid sublimate was received. When this sublimate was exposed to the air, it emitted copiou spumes of sulphuric (not sul- phurous) acid. It burned holes in paper with the rapidity of a red hot iron. By dropping a bit of it into a poised phial containing water, and stoppering instantly, to prevent the ejec- tion of liquid by the explosive ebullition that ensues, I got a dilute acid containing a known portion of the solid acid, from the specific gravity of whifh, as well as its saturating power, I determined the constitution of the solid acid to be the anhydrous sulphuric; or a compound of two by weight of sulphur and three of oxygen. M. Gmelin states in the Annales de Chimie et de Physique, for June 1826, that on distilling sulphuric acid, if we change the receiver at the instant when it is filled with opaque vapours, cover the new receiver with ice, we shall obtain anhydrous sulphuric acid, which is deposited in c-rystals on the inside of the vessel, and a less dense liquid acid which remains in the retort. He supposes that during the distillation, the sul- phuric acid is divided into two portions, one of which gives up its water to the other. The sulphuric acid made in Great Britain is produced by the combustion of sulphur. A mixture of nine parts of sulphur with one of nitre is placed in a proper vessel, enclosed within a chamber of considerable size, lined on all sides with lead, and covered at bottom with a shallow stratum of water. The mixture being set on fire will burn for a considerable time by virtue of the supply of oxygen which nitre gives out when heated, and the water imbibing the sulphurous vapours becomes gradually more and more acid after repeated combustions, and the acid is afterward con- centrated. Such was the account usually given of this operation, till MM. Clement and Desormes showed, in a very interesting memoir, its total inadequacy to account for the result 100 parts of nitre, judiciously managed, will pro- duce, with the requisite quantity of sulphur, 2000 parts of concentrated sulphuric acid. Now these contain 1200 parts of oxygen, while the hundred parts of nitre contain only 39 of oxygen ; being not ^th part of what is afterwards found in the resulting sulphuric acid. But after the combustion of the sul- phur, the nitre is converted into sulphate and bisulphate of potash, which mingled residuary salts contain nearly as much oxygen as the nitre originally did. Hence the origin of the 1200 parts of the oxygen in the sulphuric acid is still to be sought for. The following in- genious theory was first given by MM. Cle- ment and Desormes. The burning sulphur or sulphurous acid, taking from the nitre a ACI 90 ACI portion of its oxygen, forms sulphuric acid, which unites with the potash, and displaces a little nitrous and nitric acids in vapour. These vapours are decomposed by the sulphurous acid, into nitrous gas, or deutoxide of azote. This gas, naturally little denser than air, and now expanded by the heat, suddenly rises to the roof of the chamber; and might be ex- pected to escape at the aperture there, which manufacturers were always obliged to leave open, otherwise they found the acidification would not proceed. But the instant that ni- trous gas comes in contact with atmospherical oxygen, nitrous acid vapour is formed, which being a very heavy aeriform body, immediately precipitates on the sulphurous flame, and con- verts it into sulphuric acid; while itself re- suming the state of nitrous gas, reascends for a new charge of oxygen, again to redescend, and transfer it to the flaming sulphur. Thus we see, that a small volume of nitrous vapour, by its alternate metamorphoses into the states of oxide and acid, and its consequent inter- changes, may be capable of acidifying a great quantity of sulphur. This beautiful theory received a modifica- tion from Sir H. Davy. He found that nitrous gas had no action on sulphurous gas, to con- vert it into sulphuric acid, unless water be present. With a small proportion of water, 4 volumes of sulphurous acid gas, and 3 of nitrous gas, are condensed into a crystalline solid, which is instantly decomposed by abun- dance of water : oil of vitriol is formed, and nitrous gas given off", which with contact of air becomes nitrous acid gas, as above described. The process continues, according to the same principle of combination and decomposition, till the water at the bottom of the chamber is become strongly acid. It is first concentrated in large leaden pans, and afterwards in glass retorts heated in a sand bath. Platinum alembics, placed within pots of cast-iron of a corresponding shape and capacity, have been lately substituted in many manufactories for glass, and have been found to save fuel, and quicken the process of concentration. Dr. Henry describes a peculiar substance produced during very cold weather, in the leaden pipe, by which the foul air of a sul- phuric acid chamber was carried away. It was a solid resembling borax. It became soft and pasty in a warm room, and gradually a thick liquid of sp. gr. 1.831 floated over the solid part. The crystalline part, Dr. Henry considers as probably the same compound as MM. Clement and Desormes obtained by mingling sulphurous acid, nitrous gas, atmo- spheric air, and aqueous vapour ; and he thinks its constitution is probably 5 atoms sulphuric acid - 25.00 1 atom hyponitrous acid - - 4.75 5 atoms water - 5.625 35.375 Ann. of Phil xi, 368. The proper mode of burning the sulphur with the nitre, so as to produce the greatest quantity of oil of vitriol, is a problem, con- cerning which chemists hold a variety of opi- nions. M.Thenard describes the following as the best. Near one of the sides of the leaden chamber, and about a foot above its bottom, an iron plate, furnished with an upright border, is placed horizontally over a furnace, whose chimney passes across, under the bottom of the chamber, without having any connexion with it. On this plate, which is enclosed in a little chamber, the mixture of sulphur and nitre is laid. The whole being shut up, and the bottom of the large chamber covered with water, a gentle fire is kindled in the furnace. The sulphur soon takes fire, and gives birth to the products described. When the combustion is finished, which is seen through a little pane adapted to the trap-door of the chamber, this is opened, the sulphate of potash is withdrawn, and is replaced by a mixture of sulphur and nitre. The air in the great chamber is mean- while renewed by opening its lateral door, and a valve in its opposite side. Then, after closing these openings, the furnace is lighted anew. Successive mixtures are thus burned till the acid acquires a specific gravity of about 1.390, taking care never to put at once on the plate more sulphur than the air of the chamber can acidify. The acid is then withdrawn by stop- cocks, and concentrated. The following details are extracted from a paper on sulphuric acid, which I published in the 4th volume of the Journal of Science and the Arts. The best commercial sulphuric acid that I have been able to meet with contains from one-half to three quarters of a part in the hundred of solid saline matter, foreign to its nature. These fractional parts consist of sul- phate of potash and lead, in the proportion of four of the former to one of the latter. It is, I believe, difficult to manufacture it directly by the usual methods, of a purer quality. The ordinary acid sold in the shops contains often three or four per cent, of saline matter. Even more is occasionally introduced, by the em- ployment of nitre, to remove the brown colour given to the acid by carbonaceous matter. The amount of these adulterations, whether acci- dental or fraudulent, may be readily determined by evaporating in a small capsule of porcelain, or rather platinum, a definite weight of the acid. The platinum cup placed on the red cinders of a common fire will give an exact result in five minutes. If more than five grains of matter remain from five hundred of acid, we may pronounce it sophisticated. Distillation is the mode by which pure oil of vitriol is obtained. This process is described in chemical treatises as both difficult and hazardous ; but since adopting the following plan, I have found it perfectly safe and con- venient. I take a plain glass retort, capable of holding from two to four quarts of water, ACI 91 ACI and put into it about a pint measure of the sulphuric acid (and a few fragments of glass), connecting the retort with a large globular receiver, by means of a glass tubs four feet long, and from one to two inches in diameter. The tube fits very loosely at both ends. The retort is placed over a charcoal fire, and the flame is made to play gently on its bottom. When the acid begins to boil smartly, sudden explosions of dense vapour rush forth from time to time, which would infallibly break small vessels. Here, however, these expan- sions are safely permitted, by the large capacity of the retort and receiver, as well as by the easy communication with the air at both ends of the adopter tube. Should the retort, indeed, be exposed to a great intensity of flame, the vapour will no doubt be generated with in- coercible rapidity, and break the apparatus. But this accident can proceed only from gross imprudence. It resembles, in suddenness, the explosion of gunpowder, and illustrates ad- mirably Dr. Black's observation, that, but for the great latent heat of steam, a mass of water, powerfully heated, would explode on reaching the boiling temperature. I have ascertained, that tha specific caloric of the vapour of sul- phuric acid is very small, and hence the danger to which rash operators may be exposed during its distillation. Hence, also, it is unnecessary to surround the receiver with cold water, as when alcohol and most other liquids are distilled. Indeed the application of cold to the bottom of the receiver generally causes it, in the present operation, to crack. By the above method, I have made the concentrated oil of vitriol flow over in a continuous slender stream, without the globe becoming sensibly hot. I have frequently boiled the distilled acid till only one-half remained in the retort ; yet at the temperature of 60 Fahrenheit, I have never found the specific gravity of acid so con- centrated, to exceed 1.8455. It is, I believe, more exactly 1.8452. The number 1.850, which it has been the fashion to assign for the density of pure oil of vitriol, is undoubtedly very erroneous, and ought to be corrected. Genuine commercial acid should never sur- pass 1.8475 ; when it is denser, we may infer sophistication, or negligence, in the manufac- ture. The progressive increase of its density, with saline contamination, will be shown by the following experiments: To 4100 grains of genuine commercial acid (but concentrated to only 1.8350) 40 grains of dry sulphate of potash were added. When the solution was completed, the specific gravity at 60 had be- come 1.8417- We see that at these densities the addition of 0.01 of salt increases the spe- cific gravity by about 0.0067. To the above 4140 grains other 80 grains of sulphate were added, and the specific gravity, after solution, was found to be 1.8520. We perceive that somewhat more salt is now required to produce a proportional increase of density ; 0.01 of the former changing the latter by only 0.0055. Five hundred grains of this acid being eva- porated in a platinum capsule left 16^ grains, whence the composition was Sulphate of potash, with a little sulphate of lead, - ,:-* 3.30 Water of dilution, - < . . 5.3 Oil of vitriol of 1.8485, ?' .r 91.4 100.0 Thus, acid of 1.8526, which in commerce would have been accounted very strong, con- tained little more than 91 per cent, of genuine acid. Into the last acid more sulphate of potash was introduced, and solution being favoured by digestion in a moderate heat, the specific gravity became, at 60, 1.9120. Of this com- pound, 300 grains, evaporated in the platinum capsule, left 41 grains of gently ignited saline matter. We have, therefore, nearly 14 per cent. On the specific gravity in this interval, an increase of 0.0054 was effected by 0.01 of sulphate. This liquid was composed of saline matter, - - ,- '. 14. Water of dilution, - - 4.7 Oil of vitriol of 1.8485, - - 81.3 100.0 The general proportion between the density and impurity may be stated at 0.0055 of the former, to 001 of the latter. If from genuine oil of vitriol, containing -f of a per cent, of saline matter, a considerable quantity of acid be distilled off", what remains in the retort will be found very dense. At the specific gravity 1.865, such acid contains 3^ of solid salt in the 100 parts. The rest is pure concentrated acid. From such heavy acid, at the end of a few days, some minute crystals will be deposited, after which its specific gra- vity becomes 1.860, and its transparency is perfect. It contains about 2i per cent, of saline matter. Hence if the chemist employ for his researches an acid, which, though originally pretty genuine, has been exposed to long ebul- lition, he will fall into great errors. From the last experiments it appears, that concentrated oil of vitriol can take up only a little saline matter in comparison with that which is some- what dilute. It is also evident, that those who trust to specific gravity alone, for ascertaining the value of oil of vitriol, are liable to great impositions. The saline impregnation exercises an im- portant influence on all the densities at subse- quent degrees of dilution. Thus, the heavy impure concentrated acid, specific gravity 1.8650, being added to water in the proportion of one part to ten, by weight gave, after twenty- four hours, a compound whose specific gravity was 1.064- But the most concentrated genuine acid, as well as distilled acid, by the same de- gree of dilution, namely 1 -j- 10, acquires the ACI ACI specific gravity of only 1.0602, while that of 1.852, containing, as stated above, 3 per cent, of sulphate of potash combined with acid of 1*835, gives, on a similar dilution, 1.058. This difference, though very obvious to good instruments, is inappreciable by ordinary com- mercial apparatus. Hence this mode of ascer- taining the value of an acid, recommended by Mr. Dalton, is inadequate to detect a deterio- ration of even 8 or 9 per cent Had a little more salt been present in the acid, the specific gravity of the dilute, in this case, would have equalled that of the genuine. On my acide- meter one per cent of deterioration could not fail to be detected, even by those ignorant of science. The quantity of oxide, or rather sulphate of lead, which sulphuric acid can take up, is much more limited than is commonly ima- gined. To the concentrated oil of vitriol I added much carbonate of lead, and after diges- tion by a gentle heat, in a close vessel, for twenty-four hours, with occasional agitation, its specific gravity, when taken at 60, was scarcely greater than before the experiment. It contained about 0.005 of sulphate of lead. The quantity of water present in 100 parts of concentrated and pure oil of vitriol, seems to be pretty exactly 18.4G. In the experiments executed to determine the relation between the density of diluted oil of vitriol, and its acid strength, I employed a series of phials, numbered with a diamond. Into each phial, recently boiled acid, and pure water, were mixed in the successive proportions of 99 + 1 ; 98 + 2 ; 97+3, &c. through the whole range of digits down to 1 acid + 99 water. The phials were occasionally agitated during 24 hours, after which the specific gra- vity was taken. The acid was genuine and well concentrated. Its specific gravity was 1.8485. Some of the phials were kept with their acid contents for a week or two, but no further change in the density took place. The strongest possible distilled acid was employed for a few points, and gave the same results as the other. Of the three well-known modes of ascer- taining the specific gravity of a liquid, namely, that by Fahrenheit's hydrometer ; by weighing a vessel of known capacity filled with it ; and by poising a glass ball, suspended by a fine platina wire from the arm of a delicate balance I decidedly prefer the last. The corrosive- ness, viscidity, and weight of oil of vitriol, render the first two methods ineligible; whereas, by a ball floating in a liquid, of which the specific gravity does not differ much from its own, the balance, little loaded, retains its whole sensibility, and will give the most accurate consistency of results. In taking the specific gravity of concen- trated or slightly diluted acid, the temperature must be minutely regulated, because, from the small specific heat of the acid, it is easily af- fected, and because it greatly influences the density. On removing the thermometer, it will speedily rise in the air to 75 or 80, though the temperature of the apartment be only 60. Afterwards it will slowly fall to perhaps 60 or 62. If this thermometer, hav- ing its bulb covered with a film of dilute acid, (from absorption of atmospheric moisture) be plunged into a strong acid, it will instantly rise 1 0, or more, above the real temperature of the liquid. This source of embarrassment and occasional error is obviated by wiping the bulb after every immersion. An elevation of temperature, equal to 10 Fahr. diminishes the density of oil of vitriol by 0.005 ; 1000 parts being heated from 60 to 212, become 1.043 in volume, as I ascertained by very careful ex- periments. The specific gravity, which was 1,848, becomes only 1.772, being the number corresponding to a dilution of 14 per cent of water. The viscidity of oil of vitriol, which below 50 is such as to render it difficult to determine the specific gravity by a floating ball, diminishes very rapidly as the tempera- ture rises, evincing that it is a modification of cohesive attraction. The following table of densities, correspond- ing to degrees of dilution, was the result, in each point, of a particular experiment, and was, moreover, verified in a number of its- terms, by the further dilution of an acid, pre- viously combined with a known proportion of water. The balance was accurate and sen- sible. ACI ACI TABLE of the quantity of Oil of Vitriol and Dry Sulphuric Acid in 100 parts of Dilute, at different Densities, by DR. URE. Liquid. Sp. Gr. Dry. Liquid. Sp. Gr. Dry. Liquid Sp. Gr. Dry. 100 .8485 81.54 66 .5503 53.82 32 2334 26.09 99 .8475 80.72 65 .5390 53.00 31 .2260 25.28 98 .8460 79.9<> 64 .5280 52.18 30 .2184 24-46 97 .8439 79-09 63 .5170 51.37 29 .2108 23.65 96 .8410 78.28 62 .5066 50.55 28 .2032 22.83 95 .8376 77.46 61 .4960 49.74 27 .1956 22.01 94 .8336 76.65 60 .4860 48.92 26 .1876 21.20 93 .8290 75.83 59 .4760 48.11 25 .1792 20.38 92 .8233 75.02 58 .4660 47.29 24 .1706 19.57 91 .8179 74.20 57 .4560 46.48 23 .1626 18.75 90 .8115 73.39 56 .4460 45.66 22 .1549 17.94 89 .8043 72.57 55 .4360 44.85 21 .1480 17.12 88 .7962 71.75 54 .4265 44.03 20 .1410 16.31 87 .7870 70.94 53 .4170 43-22 19 .1330 15.49 86 .7774 70.12 52 .4073 42.40 18 .1246 14.68 85 .7673 69.31 51 .3977 41.58 17 .1165 13.86 84 .7570 68.49 50 .3884 40-77 16 .1090 13.05 83 .7465 67.68 49 .3788 39.95 15 .1019 12.23 82 .7360 66.86 48 .3697 39.14 14 .0953 10.41 81 .7245 66.05 47 .3612 38.32 13 .0887 11.60 80 .7120 65.23 46 .3530 37.51 12 .0809 9.78 79 .6993 64.42 45 .3440 36-69 11 .0743 8.97 78 6870 63.60 44 .3345 35-88 10 .0682 8.15 77 .6750 62.78 43 .3255 35.06 9 .0614 7.34 76 .6630 61.97 42 .3165 34.25 8 .0544 6.52 75 .6520 61-15 41 .3080 33.43 7 .0477 5.71 74 .6415 60.34 40 .2999 32.61 6 .0405 4.89 73 .6321 59-52 39 .2913 3 1 -80 5 1.0336 4.08 ' 72 .t>204 58.71 38 .2826 30.98 4 1.0268 3.26 71 .6090 57.89 37 .2740 30. 1 7 3 1-0206 2.446 70 5975 57.08 36 .2654 29.35 '2 1-0140 1.63 69 .5868 56.26 35 .2572 28.54 1 1.0074 0.8154 68 .5760 55.45 34 1.2490 27.72 67 .5648 54.63 33 1 .2409 26.91 In order to compare the densities of the preceding dilute acid, with those of distilled and again concentrated acid, I mixed one part of the latter with nine of pure water, and after agitation, and a proper interval, to ensure thorough combination, I found its specific gravity as above, 1.0682: greater density in- dicates saline contamination. Dilute acid having a specific gravity n: 1.6321, has suffered the greatest condensation ; 100 parts in bulk have become 92.14. If either more or less acid exist in the compound, the volume will be increased. What reason can be assigned for the maximum condensa- tion occurring at this particular term of dilu- tion ? The above dilute acid consists of 73 per cent, of oil of vitriol, and 27 of water. But 73 of the former contains, by this Table, 59.52 of dry acid, and 13.48 of water. Hence 100 of the dilute acid consist of 59.52 of dry acid, -f 13.48 X 3 = 40,44 of water = 99.96 ; or it is a compound of one atom of dry acid, with three atoms of water. Dry sulphuric acid consists of three atoms of oxygen, united to one of sulphur. Here each atom of oxygen is associated with one of water, forming a sym- metrical arrangement. We may therefore infer, that the least deviation from the above definite proportions must impair the balance of the attractive forces, whence they will act less efficaciously, and therefore produce less con- densation. The very minute and patient examination which I was induced to bestow on the table of specific gravities, disclosed to me the general law pervading the whole, and consequently the means of inferring at once the density from the degree of dilution, as also of solving the inverse proposition. If we take the specific gravity, correspond- ing to ten per cent, of oil of vitriol, or 1.0682 as the root ; then the specific gravities at the successive terms of 20, 30, 40, &c. will be the successive powers of that root. The terms of dilution are like logarithms, a series of num- bers in arithmetical progression, corresponding ACI 94 ACI to another series, namely, the specific gravities in geometrical progression. The simplest logarithmic formula which I have been able to contrive is the following. 2a Log. S = ^ where S is the specific gravity, /oo and a the per centage of acid. And a Log. S X 350. In common language the two rules may be stated thus. Problem 1st, To find the proportion of oil of vitriol in dilute acid of a given specific gra- vity. Multiply the logarithm of the specific gravity by 350, the product is directly the per centage of acid. If the dry acid be sought, we must multiply the logarithm of the specific gravity by 285, and the product will be the answer. Problem 2d, To find the specific gravity corresponding to a given proportion of acid. Multiply the quantity of acid by 2, and divide by 700; the quotient is the logarithm of the specific gravity. Table of distilled sulphuric acid for the higher points, below which it agrees with the former table. Liquid Acid in 100. Sp. Gr. Dry Acid. 100 1.84(5 81.63 95 1 .834 77.55 90 1.807 73.47 85 1.764 6.9.39 80 1.708 65.30 75 1.650 61.22 Sulphuric acid strongly attracts water, which it takes from the atmosphere very rapidly, and in larger quantities, if suffered to remain in an open vessel, imbibing one-third of its weight in twenty-four hours, and more than six times its weight in a twelvemonth. If four parts by weight be mixed with one of water at 50, they produce an instantaneous heat of 300 F. ; and four parts raise one of ice to 212 : on the contrary, four parts of ice, mixed with one of acid, sink the thermometer to 4 below 0. It requires a great degree of cold to freeze it ; and if diluted with half a part or more of water, unless the dilution be carried very far, it becomes more and more difficult to congeal ; yet at the specific gravity of l.Tfy or a few hundredths above or below this, it may be frozen by surrounding it with melting snow. Its congelation forms regular prismatic crystals with six sides. Its boiling point, according to Bergman, is 540; according to Dalton, 590". Sulphuric acid consists of three prime equi- valents of oxygen, one of sulphur, and one of water ; and by weight, therefore, of 3.0 oxy- gen + 2.0 sulphur + 1.125 water = 6.125, which represents the prime equivalent of the concentrated liquid acid ; while 3 -j- 2 5, will be that of the dry acid. Pure sulphuric acid is without smell and colour, and of an oily consistence. Its action on litmus is so strong, that a single drop of acid will give to an immense quantity of water the power of reddening. It is a most violent caustic ; and has sometimes been administered with the most criminal purposes. The person who unfortunately swallows it, speedily dies in dreadful agonies and convulsions Chalk, or common carbonate of magnesia, is the best antidote for this, as well as for the strong nitric and muriatic acids. When transmitted through an ignited por- celain tube of one-fifth of an inch diameter, it is resolved into two parts of sulphurous acid gas, and one of oxygen gas, with water. Vol- taic electricity causes an evolution of sulphur at the negative pole ; whilst a sulphate of the metallic wire is formed at the positive. Sul- phuric acid has no action on oxygen gas or air. It merely abstracts their aqueous vapour. If the oxygenized muriatic acid of M. Thenard be put in contact with the sulphate of silver, there is immediately formed insoluble chloride of silver, and oxygenized sulphuric acid. To obtain sulphuric acid in the highest degree of oxygenation, it is merely necessary to pour barytes water into the above oxygen- ized acid, so as to precipitate only a part of it, leaving the rest in union with the whole of the oxygen. Oxygenized sulphuric acid partially reduces the oxide of silver, occasioning a strong effervescence. See ACID. All the simple combustibles decompose sul- phuric acid, with the assistance of heat. About 400 Fahr. sulphur converts sulphuric into sulphurous acid. Several metals at an ele- vated temperature decompose this acid, with evolution of sulphurous acid gas, oxidizement of the metal, and combination of the oxide with the undecomposed portion of the acid. Sulphuric acid is of very extensive use in the art of chemistry, as well as in metallurgy, bleaching, and some of the processes for dye- ing; in medicine it is given as a tonic and stimulant, and is sometimes used externally as a caustic. The combinations of this acid with the various bases are called sulphates, and most of them have long been known by various names. With barytes it is found native and nearly pure in various forms. See HEAVY SPAR. It may be artificially formed by dropping a solution of an alkaline sulphate into the solution of muriate or nitrate of barytes. It forms a white powder which suffers no change by the action of the air, and is therefore sometimes used in water-colour painting. It consists, according to Dr. Wollastan, of 5 parts of dry acid, and 9-75 of barytes. It requires 43,000 parts of water to dissolve it at Sulphate of strontian has a considerable re- semblance to that of barytes in its properties. ACI 95 ACI It is found native in considerable quantities at Aust Passage and other places in the neigh- bourhood of Bristol. It requires 3840 parts of boiling water to dissolve it. Its composition is 5 acid -f- 6.5 base. The sulphate of potash, formerly vitriolated tartar, crystallizes in hexaedral prisms, termi- nated by hexagonal pyramids, but susceptible of variations. Its crystallization by quick cooling is confused. Its taste is bitter, acrid, and a little saline. It is soluble in 5 parts of boiling water, and 16 parts at 60. In the fire it decrepitates, and is fusible by a strong heat. It is decomposable by charcoal at a high temperature. It may be prepared by direct mixture of its component parts ; but the usual and cheapest mode is to ignite the acidulous sulphate left after distilling nitric acid. The sal polychrcst of old dispensatories, made by de- flagrating sulphur and nitre in a crucible, was a compound of the sulphate and sulphite of potash. The acidulous sulphate is sometimes employed as a flux, and likewise in the manu- facture of alum. In medicine the neutral salt is sometimes used as a mild cathartic. It consists of 5 acid -f- C base ; but there is a compound of the same constituents, in the proportion of 10 acid + 6 potash, called the bi-sulphate. The sulphate of soda is the well known Glauber's salt. It is commonly prepared from the residuum left after distilling muriatic acid, the superfluous acid of which may be expelled by ignition ; and is likewise obtained in the manufacture of the muriate of ammonia. (See AMMONIA.) It exists in large quantities under the surface of the earth in some coun- tries, as Persia, Bohemia, and Switzerland ; is found mixed with other substances in mineral springs and sea water ; and sometimes efflor- esces on Avails. Sulphate of soda is bitter and saline to the taste. It is soluble in 2.85 parts of cold water, and 0.8 at a boiling heat; it crystallizes in hexagonal prisms bevelled at the extremities, sometimes grooved longi- tudinally, and of very large size, when the quantity is great : these effloresce completely into a white powder if exposed to a dry air, or even if kept wrapped up in paper in a dry place ; yet they retain sufficient water of crys- tallization to undergo the aqueous fusion on exposure to heat, but by urging the fire, melt Barytes and strontian take its acid from it entirely, and potash partially ; the nitric and muriatic acids, though they have a weaker affinity for its base, combine with a part of it when digested on it Heated with charcoal its acid is decomposed. As a purgative its use is very general ; and it has been employed to furnish soda. Pajot des Charmes has made some experiments on it in fabricating glass ; with sand alone it would not succeed, but equal parts of carbonate of lime, sand, and dried sulphate of soda, produced a clear, solid, pale yellow glass. It is composed of 5 acid -}- 4 base -f 11.25 water in crystals ; when dry, the former two primes are its constituents. Sulphate of soda and sulphate of ammonia form together a triple salt Sulphate of lime, selcnite, gypsum, plaster of Paris, or sometimes alabaster, form ex- tensive strata in various mountains. (See GYPSUM.) It requires 500 parts of cold water, and 450 of hot, to dissolve it When calcined, it de- crepitates, becomes very friable and white, and heats a little with water, with which it forms a solid mass. In this process it loses its water of crystallization. The calcined sulphate is much employed for making casts of anatomical and ornamental figures ; as one of the bases of stucco ; as a fine cement for making close and strong joints between stone, and joining rims or tops of metal to glass ; for making moulds for the Staffordshire potteries; for cornices, mouldings, and other ornaments in building. For these purposes, and for being wrought into columns, chimney-pieces, and various ornaments, about eight hundred tons are raised annually in Derbyshire, where it is called alabaster. In America it is laid on grass land as a manure. Ordinary crystallized gypsum consists of 5 sulphuric acid + 3.5 lime + 2.25 water ; the anhydrous variety wants of course the last in- gredient Sulphate of magnesia is commonly known by the name of Epsom salt, as it was fur- nished in considerable quantity by the mineral water at that place, mixed, however, with a considerable portion of sulphate of soda. It is afforded, however, in greater abundance and more pure from the bittern left after the ex- traction of salt from sea water. It has like- wise been found efflorescing on brick walls, both old and recently erected, and in small quantity in the ashes of coals. The capillary salt of Idria, found in silvery crystals mixed with the aluminous schist in the mines of that place, and hitherto considered as a feathery alum, has been ascertained by Klaproth to consist of sulphate of magnesia, mixed with a small portion of sulphate of iron. When pure it crystallizes in small quadrangular prisms, terminated by quadrangular pyramids or diedral summits. Its taste is cool and bitter. It is very soluble, requiring only an equal weight of cold water, and three-fourths its weight of hot It effloresces in the air, though but slowly. If it attract moisture, it contains muriate of magnesia or of lime. Ex- posed to heat, it dissolves in its own water of crystallization, and dries, but is not decom- posed, nor fused, but with extreme difficulty. It consists, according to Bergman, of 33 acid, 19 magnesia, 48 water. A very pure sulphate is said to be prepared in the neighbourhood of Genoa, by roasting a pyrites found there ; ex- posing it to the air in a covered place for six ACI 96 ACI months, watering it occasionally, and then lixiviating. Sulphate of magnesia is one of our most valuable purgatives ; for which purpose only it is used, and for furnishing the carbonate of magnesia. It is composed of 5 acid + 2.5 magnesia 4- 7.875 water, in the state of crystals. Sulphate of ammonia crystallizes in slen- der, flattened, hexaedral prisms, terminated by hexagonal pyramids ; it attracts a little moisture from very damp air, particularly if the acid be in excess ; it dissolves in two parts of cold and one of boiling water. It is not used, though Glauber, who called it his secret ammoniacal salt, vaunted its excellence in assaying. It consists of 5 acid + 2.125 ammonia -f- 1.125 water in its most desiccated state ; and in its crystalline state of 5 acid + 2.125 am- monia 4- 3.375 water. If sulphate of ammonia and sulphate of magnesia be added together in solution, they combine into a triple salt of an octaedral figure, but varying much ; less soluble than either of its component parts ; unalterable in the air; undergoing on the fire the watery fusion ; after which it is decomposed, part of the ammonia flying off, and the remainder subliming with an excess of acid. It con- tains, according to Fourcroy, 6'8 sulphate of magnesia, and 32 sulphate of ammonia. Sulphate of glucina crystallizes with diffi- culty, its solution readily acquiring and re- taining a syrupy consistence; its taste is sweet, and slightly astringent ; it is not alter- able in the air ; a strong heat expels its acid, and leaves the earth pure ; heated with char- coal it forms a sulphuret; infusion of galls forms a yellowish-white precipitate with its solution. Yttria is readily dissolved by sulphuric acid; and as the solution goes on, the sul- phate crystallizes in small brilliant grains, which have a sweetish taste, but less so than sulphate of glucina, and are of a light ame- thyst-red colour. They require 30 parts of cold water to dissolve them, and give up their acid when exposed to a high temperature. They are decomposed by oxalic acid, prussiate of potash, infusion of galls, and phosphate of soda. Sulphate of alumina in its pure state is but recently known, and it was first attentively examined by Vauquelin. It may be made by dissolving pure alumina in pure sulphuric acid, heating them for some time, evaporating the solution to dryness, drying the residuum with a pretty strong heat, redissolving it, and crystallizing. Its crystals are soft, foliaceous, shining, and pearly ; but these are not easily obtained without cautious evaporation and re- frigeration. They have an astringent taste ; are little alterable in the air ; are pretty solu- ble, particularly in hot water ; give out their acid on exposure to a high temperature; are decomposable by combustible substances, though not readily ; and do not form a pyro- phorus like alum. If the evaporation and desiccation directed above be omitted, the alumina will remain supersaturated with acid, as may be known by its taste, and by its reddening vegetable blue. This is still more difficult to crystal- lize than the neutral salt, and frequently thickens into a gelatinous mass. A compound of acidulous sulphate of alumina with potash or ammonia has long been known by the name of ALUM. See ALUMINA. If this acidulous sulphate or alum be dis- solved in water, and boiled with pure alu- mina, the alumina will become saturated with its base, and fall down an insipid white pow- der. This salt is completely insoluble, and is not deprived of its acid by heat but at a very high temperature. It may be decomposed by long boiling with the alkaline or earth bases ; and several acids convert it into common alum, but slowly. Sulphate of zircon may be prepared by adding sulphuric acid to the earth recently precipitated, and not yet dry. It is some- times in small needles, but commonly pul- verulent ; very friable ; insipid ; insoluble in water, unless it contain some acid ; and easily decomposed by heat. ACID (SULPHUROUS). This acid is formed by the ordinary combustion of sul- phur in the open air : but it can be obtained most purely and conveniently by digesting mercury in sulphuric acid, with heat, in a re- tort. The metal becomes oxidized, and sul- phurous acid gas is disengaged with effer- vescence. M. Berthier has recently shown that sulphurous acid gas may be obtained very pure and abundantly, by heating a mix- ture of twelve or fourteen parts of sublimed sulphur and a hundred parts of peroxide of manganese in a glass retort. The residue in the retort is not a sulphuret of manganese, but a protoxide of that metal, mixed with a little sulphate, and sometimes a little sul- phur. Ann. de Chim. ct dc Phys. xxiv. 275. The gas may be collected over quicksilver, or received into water, which at the tempera- ture of 61 will absorb 33 times its bulk, or nearly an eleventh of its weight. Water thus saturated is intensely acid to the taste, and has the smell of sulphur burn- ing slowly. It destroys most vegetable co- lours, but the blues are reddened by it pre- vious to their being discharged. A pleasing instance of its effect on colours may be ex- hibited by holding a red rose over the blue flame of a common match, by which the colour will be discharged wherever the sul- phurous acid comes into contact with it, so as to render it beautifully variegated, or entirely ACI 97 ACI white. If it be then dipped into water, the redness after a time will be restored. The specific gravity of sulphurous acid gas, as given by MM. Thcnard and Gay Lussac, is 2-2553, but by Sir H. Davy is 2.2295, and hence 100 cubic inches weigh 68 grains ; but its spr. gr. most probably should be estimated at 2.222, and the weight of 100 cubic inches will become 67.777* Its constituents by vo- lume are one of oxygen, and one of vapour of sulphur ; each having a sp. gr. of 1.111, con- densed so that both volumes occupy only one. Or in popular language, sulphurous acid may be said to be a solution of sulphur in oxygen, which doubles the weight of this gas, without augmenting its bulk. It obviously, therefore, consists by weight of equal quantities of the two constituents. Its equivalent will either be 2 oxygen + 2 sulphur n 4.0 ; or 1 oxy- gen + 1 sulphur = 2. Now the analysis of sulphite of barytes by Berzelius gives 209-22 base to 86.53 acid ; which being reduced, presents for the prime equivalent of sulphu- rous acid, the number 4. Hydrogen and carbon readily decompose sulphurous acid at a red heat, and even under it. Mr. Higgins discovered, that liquid sulphurous acid dis- solves iron, without the evolution of any gas. The peroxides of lead and manganese furnish oxygen to convert it into sulphuric acid, which forms a sulphate, with the resulting metallic protoxide. Sulphurous acid is used in bleaching, par- ticularly for silks. It likewise discharges vegetable stains and iron-moulds from linen. In combination with the salifiable bases, it forms sulphites which differ from the sul- phates in their properties. The alkaline sul- phites are more soluble than the sulphates, the earthy less. They are converted into sulphates by an addition of oxygen, which they acquire even by exposure to the air. The sulphite of lime is the slowest to undergo this change. A strong heat either expels their acid entirely, or converts them into sul- phates. They have all a sharp, disagreeable, sulphurous taste. The best mode of obtaining them is by receiving the sulphurous acid gas into water, holding the base, or its carbonate, in solution, or diffused in it in fine powder. None of them has yet been applied to any use. By putting sulphuric acid and mercury into the sealed end of a glass tube recurved, then sealing the other end, and applying heat to the former, Mr. Faraday obtained a liquid sulphurous acid. (Ph. Tr. 1823.) Mr. Bussy (Ann. de Chim. for May, 1824) says that he liquefied the same gas, by transmitting it through fused chloride of calcium into a flask surrounded with a mixture of ice and salt. It remains in a liquid state in the air at the temperature of F. It is a colourless transparent, and very volatile liquid, of a spe- cific gravity = 1.45. It boils at 14 F. but in consequence of the cold produced by the evaporation of the portion that flies off, the residue remains liquid. It causes a feeling cf intense cold when dropped on the hand. By evaporation of the acid in vacua, M. Bussy froze alcohol, sp. gr. 0.850. ACID (IIYPOSULPHUKOUS). In the 85th volume of the Annales de Chimie, M. Gay Lussac describes permanent crystal- lizable salts having lime and strontites for their base, combined with an acid of sulphur, in which the proportion of oxygen is less than in sulphurous acid ; but this acid he does not seem to have examined in a separate state. Those salts were procured by exposing so- lutions of the sulphurets of the earths to the air, when sulphur and carbonate of lime precipitated. When the filtered liquid is then evaporated, and cooled, colourless crystals form. The calcareous are prismatic needles, and those with strontites are rhomboidal. He called these new compounds sulphuretted sul- phites. Those of potash and soda he also formed, by heating their sulphites with sul- phur ; when a quantity of sulphurous acid was disengaged, and neutral salts were formed. M. Gay Lussac farther informs us, that boil- ing a solution of a sulphite with sulphur, de- termines the formation of the sulphuretted sulphite, or hyposulphite ; and that iron, zinc, and manganese, treated with liquid sulphur- ous acid, yield sulphuretted sulphites ; from which it follows, that a portion of the sul- phurous acid is decomposed by the metal, and that the resulting oxide combines with the other portion of the sulphurous acid and the liberated sulphur. The hyposulphites are more permanent than the sulphites ; they do not readily pass by the action of the air into the state of sulphate; and though decom- posable at a high heat, they resist the action of fire longer than the sulphites. They are decomposed in solution by the sulphuric, mu- riatic, fluoric, phosphoric, and arsenic acids ; sulphurous acid is evolved, sulphur is pre- cipitated, and a new salt is formed. Such is the account given of these by M. Gay Lussac, and copied into the second volume of the Traite de Chimie of M. Thenard, published in 1814. No additional information was communi cated to the world on this subject till January 1819, when an ingenious paper on the hypo- sulphites appeared in the Edinburgh Philo- sophical Journal, followed soon by two others in the same periodical work, by Mr. Herschel. In order to obtain hyposulphurous acid, Mr. Herschel mixed a dilute solution of hy- posulphite of strontites with a slight excess of dilute sulphuric acid, and after agitation poured the mixture on three filters. The first was received into a solution of carbonate of potash, from which it expelled carbonic acid gas. The second portion being received suc- cessively into nitrates of silver and mercury, precipitated the metals copiously in the state ACI 98 ACI of su.lphurets, but produced no effect on solu- tions of copper, iron, or zinc. The third, being tasted, was acid, astringent, and bitter. When fresh filtered, it was clear ; but it be- came milky on standing, depositing sulphur, and colouring sulphurous acid. A moderate exposure to air, or a gentle heat, caused its entire decomposition. The habitudes of oxide of silver in union with this acid, are very peculiar. Hyposul- phite of soda being poured on newly preci- pitated oxide of silver, hyposulphite of silver was formed, and caustic soda eliminated ; the only -instance, says Mr. Herschel, yet known, of the direct displacement of a fixed alkali by a metallic oxide, via humida. On the other hand, hyposulphurous acid newly disengaged from the hyposulphite of barytes, by dilute sulphuric acid, readily dissolved, and decom- posed muriate of silver, forming a sweet solu- tion, from which alcohol separated the metal in the state of hyposulphite. " Thus the affinity between this acid and base, unassisted ly any double decomposition, is such as to form an exception to all the ordinary rules of chemical union." This acid has a remark- able tendency to form double salts with the oxides of silver and alkaline bases. The hy- posulphite of silver and soda has an intensely sweet taste. When hyposulphite of ammonia is poured on muriate of silver, it dissolves it ; and if into the saturated solution alcohol be poured, a white salt is precipitated, which must be forcibly squeezed between blotting paper, and dried in vacua. It is very soluble in water. Its sweetness is unmixed with any other flavour, and so intense as to cause pain in the throat. One grain of the salt commu- nicates a perceptible sv/eetness to 32,000 grains of water. If the alcoholic liquid be evaporated, thin lengthened hexangular plates are sometimes formed, which are not altered by keeping, and consist of the same principles. The best way of obtaining the alkaline hy- posulphites, is to pass a current of sulphurous acid gas through a lixivium, formed by boil- ing a watery solution of alkali, or alkaline earth, along with sulphur. The whole of the sulphurous acid is converted into the hypo- sulphite, and pure sulphur, unmixed with any sulphite, is precipitated, while the hyposulphite remains in solution. Mr. Herschel, from his experiments on the hyposulphite of lime, has deduced the prime equivalent of hyposulphurous acid to be 59.25. He found that 100 parts of crystallized hypo- sulphite of lime were equivalent to 121-77 hyposulphite of lead, and yielded of carbonate of lime, by carbonate of ammonia, a quantity equivalent to 21.75 gr. of lime. Therefore the theory of equivalent ratios gives us this rule: As 21.75 gr. lime are to its prime equiva- lent 3.5, so are 121.77 gr- of hyposulphite of lead, to its prime equivalent. In numbers 21.75 : 3.5 : : 121.77 : 19.6. From this number, if we deduct the prime of the oxide of lead = 14, the remainder 5.6 will be the double prime of hyposulphurous acid. Now this number does not materially differ from 6. Hence we see that the hyposulphites, for their neutral condition, require of this feeble acid 2 prime proportions. One prime proportion of it is obviously made up of 1 prime of sulphur n 2, -j- 1 oxygen = 1 ; and the acid equi- valent is 3. The crystallized hyposulphite of lime is composed of 6. acid -(-3.5 lime -j- G-75 water, being 6 prunes of the last consti- tuent It ought to be stated, that when a solution of a hyposulphite is boiled down to a certain degree of concentration, it begins to be rapidly decomposed, with the deposition of sulphur and sulphite of lime. To obtain the salt in crystals, the solution must be evaporated at a temperature not exceeding 140 Fahr. If it be then filtered while hot, it will yield, on cooling, large and exceedingly beautiful crys- tals, which assume a great variety of compli- cated forms. They are soluble in nearly their own weight of water at 37 Fahr. and the tem- perature of the solution falls to 31. The spe- cific gravity of their saturated solution at 60 is 1.300; and when it is 1.114, the liquid contains one-fifth of its weight. The crystals are permanent in the air. Hyposulphites of potash and soda yield de- liquescent crystals of a bitter taste, and both of them dissolve muriate of silver. The am- moniacal salt is not easily procured in regular crystals. Its taste is pungent and disagreeable. The barytic hyposulphite is insoluble; the strontitic is soluble and crystallizable. Like the other hyposulphites, it dissolves silver; and while its own taste is purely bitter, it pro- duces a sweet compound with muriate of silver, which alcohol throws down in a syrupy form. Hyposulphite of magnesia is a bitter tasted, soluble, crystallizable, and non-deliquescent salt. All the hyposulphites burn with a sul- phurous flame. The sweetness of liquid hy- posulphite of soda, combined with muriate of silver, surpasses honey in intensity, diffusing itself over the whole mouth and fauces with- out any disagreeable or metallic flavour. A coil of zinc wire speedily separates the silver in a metallic state, thus affording a ready ana- lysis of muriate of silver. Muriate of lead is also soluble in the hyposulphites, but less rea- dily. ACID (HYPOSULPHURIC). MM. Gay Lussac and Welther have recently an. nounced the discovery of a new acid combina- tion of sulphur and oxygen, intermediate be- tween sulphurous and sulphuric acids, to which they have given the name of hyposulphuric acid. It is obtained by passing a current of sulphurous acid gas over the black oxide of manganese. A combination takes place ; the excess of the oxide of manganese is separated ACI 99 ACI by dissolving the hyposulphate of manganese in water. Caustic barytes precipitates the manganese, and forms with the new acid a very soluble salt, which, freed from excess of barytes by a current of carbonic acid, crystal- lizes regularly, like the nitrate or muriate of barytes. Hyposulphate of barytes being thus obtained, sulphuric acid is cautiously added to the solution, which throws down the bary- tes, and leaves the hyposulphuric acid in the water. This acid bears considerable concen- tration under the receiver of the air-pump. It consists of five parts of oxygen to four of sul- phur. The greater number of the hyposul- phates, both earthy and metallic, are soluble, and crystallize ; those of barytes and lime are unalterable in the air. Suberic acid and cMo- rine do not decompose the barytic salt. The barytic salt in crystals consists of barytes 9.75 -f hyposulphuric acid 9.00 + water 2.25 = 20.95. The following table exhibits the composition of the different acid compounds of sulphur and oxygen : Hyposulphurous acid, 20 sul. -f- 10 oxygen Sulphurous acid, 10 -}~ 10 Hyposulphuric acid, 8 -f- 10 Sulphuric acid, 6| +10 Or if we prefer to consider the quantity of sulphur in each acid as = 2, the oxygen com- bines with it in the following proportions : 1; 2; 2.5; 3. Hyposulphuric acid is distinguished by the following properties: 1st, It is decomposed by heat into sulphur- ous and sulphuric acids. 2d, It forms soluble salts with barytes, stron- tites, lime, lead, and silver. 3d, The hyposulphates are all soluble. 4th, They yield sulphurous acid when their solutions are mixed with acids, only if the mixture becomes hot of itself, or be artificially heated. 5th, They disengage a great deal of sul- phurous acid at a high temperature, and are converted into neutral sulphates. Before quitting the acids of sulphur, it de- serves to be mentioned, that Dr. Gules, of Paris, has, by means of a chest or case, called Boe'te Fumigatoire, applied the vapour of burn- ing sulphur, or sulphurous acid gas, mixed with air, to the surface of the body, as an air bath, with great advantage, in many chronic diseases of the skin, the joints, the glands, and the lymphatic system See SALT. ACID (SULPHO-NAPHTHALIC). Mr. Faraday communicated a paper, in 1826, to the Royal Society, to show that during the mutual action of sulphuric acid and naphtha- line, a compound of that acid with hydro-carbon is formed, differing from all known substances, and which possessing acid properties, and combining with salifiable bases to produce a peculiar class of salts, has been distinguished as the sulpho-naphthalic acid. Let two parts of naphthaline and one part of concentrated sulphuric acid be introduced into a flask, raise the temperature till the naphthaline melts, and agitate. Combination is effected, and, after cooling, two substances are found, both in the solid state. The lighter is naphthaline, con- taining a little of the peculiar acid. The lower and heavier is also crystalline, but softer than the upper. It is red, of an acid bitter taste, absorbs moisture from die air, and con- sists principally of the hydrated peculiar acid, containing some uncombined naphthaline. It is distinguished as the impure solid acid. On rubbing this with native carbonate of barytes in a mortar, a soluble barytic salt was ob- tained. To the solution of this salt, sulphuric acid was carefully added just in quantity suf- ficient to precipitate the barytes; and after filtration a pure aqueous solution of the new acid was obtained. This solution is bitter, acid, neut tes or lead from evaporated in vacua, it affords a white, solid", crystalline acid, deliquescing in the air. It melts at 212 Fahr. and crystallizes on cool- ing. Its salts are soluble in water and alcohol. That of barytes is composed of an atom of barytes, 2 of sulphuric acid, 20 of charcoal, and 8 of hydrogen. Its saturating power is equal to one half that of its sulphuric acid. ACID (SULPHOVINIC). Salts called sulphovinates were fiist noticed about the year 1800 by M. Dabit, and afterwards treated of by M. Vogel ; but their nature was never ascertained till Mr. Hennel mads his investi- gations lately on the subject. The sulpho- vinates are readily prepared by mixing equal weights of sulphuric acid and alcohol ; allow- ing the mixture to remain for half an hour, then adding carbonate of lead equal in weight to that of the sulphuric acid first used, and, filtering, little else than sulphovinic acid is left in solution. This combined with bases furnishes salts, which may be rendered pure by crystallization. Sulphovinic acid, accord- ing to Mr. Hennel, consists of two atoms of sulphuric acid, four of hydrogen, and four of carbon; and this compound acid combines with one atom of potash to form sulphovinate of potash. The vegetable part of the acid is therefore olefiant gas. Oil of wine and sulpho- vinic acid seem to be identical. Phil. Trans. 1826. Part 3. See OIL OF WINE. ACID (TARTARIC). The casks in which some kinds of wine are kept become in- crusted with a hard substance, tinged with the colouring matter of the wine, and otherwise impure, which has long been known by the name of argal, or tartar, and distinguished into red and white, according to its colour. This being purified was termed cream, or crys- tals of tartar. It was afterwards discovered, that it consisted of a peculiar acid combined with potash ; and the supposition that it was H 2 ACI 100 ACI formed during the fermentation of the wine was disproved by Boerhaave, Neuman, and others, who showed that it existed ready formed in the juice of the grape. It has likewise been found in other fruits, particularly before they are too ripe; and in the tamarind, sumac, balm, carduus benedictus, and the roots of restharrow, germander, and sage. The separa- tion of tartaric acid from this acidulous salt is the first discovery of Scheele that is known. He saturated the superfluous acid, by adding chalk to a solution of die supertartrate hi boiling water as long as any effervescence ensued, and expelled the acid from the precipitated tartrate of lime by means of the sulphuric. Or four parts of tartar may be boiled in twenty or twenty-four of water, and one part of sulphu- ric acid added gradually. By continuing the boiling, the sulphate of potash will fall down. When the liquor is reduced to one-half, it is to be filtered ; and if any more sulphate be deposited by continuing the boiling, the filter- ing must be repeated. When no more is thrown down, the liquor is to be evaporated to the con- sistence of a syrup ; and thus crystals of im- pure tartaric acid, equal to half the weight of the tartar employed, will be obtained. Tartaric acid may be procured by careful evaporation in large crystals, which, when in- sulated, are found to be hexaedral prisms, with faces parallel, two and two. The four angles which are most obtuse are equal to one another, measuring each 129; the two re- maining ones are also equal, and measure 102. The prism is terminated by a three-sided py- ramid, the inclinations of whose faces are 102.5, 122, and 125. The prisms are sometimes much compressed in a direction parallel to the axis. This takes place when the acid has been very slowly crystallized by evaporating a so- lution of it. Its taste is very acid and agree- able, so that it may supply the place of lemon- juice. It is very soluble in water. Burnt in an open fire, it leaves a coaly residuum ; in close vessels it gives out carbonic acid and car- buretted hydrogen gas. By distilling nitric acid off the crystals, they may be converted into oxalic acid, and the nitric acid passes to the state of nitrous. To extract the whole acid from tartar, M. Thenard recommends, after saturating the re- dundant acid with chalk, to add muriate of lime to the supernatant neutral tartrate, by which means it is completely decomposed. The insoluble tartrate of lime being washed with abundance of water, is then to be treated with three-fifths of its weight of strong sul- phuric acid, diluted previously with five parts of water. But Fourcroy's process, as im- proved by Vauquelin, seems cheaper. Tartar is treated with quicklime and boiling water in the proportion, by the theory of equivalents, of 100 of tartar to 30 of dry lime, or 40 of the slaked. A caustic magma is obtained, which must be evaporated to dryness, and gently heated. On digesting this in water, a solution of caustic potash is obtained, while tartrate of lime remains ; from which the acid may be separated by the equivalent quantity of oil of vitriol. According to Berzelius, tartaric acid is a compound of 3.807 hydrogen -f- 35.980 car- bon + 00.213 oxygen = 100 ; to which result he shows that of M. Gay Lussac and Thenard to correspond, when allowance is made for a certain portion of water, which they had omit- ted to estimate. The analysis of tartrate of lead, gives 8 384 for the acid prime equiva- lent ; and it may be made up of 3 hydrogen = 0.375 4.48 4 carbon = 3.000 35.82 5 oxygen = 5.000 59-70 8.375 100.00 The crystallized acid is a compound of 8.375 acid -f 1.125 water = 9.5; or in 100 parts 88.15 acid + 11.85 water. The prime equivalent of tartaric acid in crystals is, by my results, 9.25 ; and it seems made up of carbon 4 atoms 3 + hydrogen 2 atoms = 0.25 -f- oxygen 6=6; or of car- bon 4 atoms, oxygen 4 atoms, and water 2. These atoms of water enter into dry tartrate of lead j and hence the crystals of acid con- tain no water unessential to their constitution. Phil. Trans. 1822. Mr. Rose has shown, that tartaric acid has a peculiar influence in several cases of chemical analysis. When a solution of red oxide of iron is mixed with tartaric acid, the oxide can be precipitated neither by caustic alkalis, nor by their carbonates or succmates ; but tincture of galls, triple prussiate of potash, and alkaline hydrosulphurets, show the presence of iron in such a solution. The same thing is true of the oxides of titanium, manganese, cerium, yttrium, cobalt, and nickel, as well as with alumina and magnesia. Solution of proto- sulphate of iron with tartaric acid is merely rendered intensely green by ammonia, and changes after long standing in the air to a yellow coloured solution, which contains iron. The oxide of lead likewise is not separable by alkalis when its solution has been treated with so much nitric acid that no tartrate of lead can precipitate. Oxides of tin and cop- per fall under the same head. Lastly, oxide of antimony, when its solution in an acid is mixed with the tartaric, resists both alkalis and the most copious dilution with water. Thus, oxide of bismuth may be separated from oxide of antimony ; for the former re- sists the influence of tartaric acid. Muriate of platinum, the oxides of silver, zinc, and uranium, are not altered by tartaric acid. Gilbert's Ann. Ixxiii. 74. The tartrates in their decomposition by fire comport themselves like all the other vege- table salts, except that those with excess of acid yield the smell of caromel when heated, AC I 101 ACI and afford a certain quantity of the pyrotartaric acid. All the soluble neutral tartrates form, withtartaric acid, bitartrates of sparing solubi- lity ; while all the insoluble tartrates may be dis- solved in an excess of their acid. Hence, by pouring gradually an excess of acid into ba- rytes, strontites, and lime waters, the pre- cipitates formed at first cannot fail to disap- pear; while those obtained by an excess of the same acid, added to concentrated solutions of potash, soda, or ammonia, and the neutral tartrates of these bases as well as of magnesia and copper, must be permanent. The first are always flocculent ; the second always crys- talline ; that of copper alone, is in a greenish- white powder. It likewise follows, that the greater number of acids ought to disturb the solutions of the alkaline neutral tartrates, be- cause they transform these salts into bitartrates ; and on the contrary they ought to affect the solution of the neutral insoluble tartrates, which indeed always happens, unless the acid cannot dissolve the base of the tartrate. The order of apparent affinities of tartaric acid are, lime, barytes, strontites, potash, soda, ammonia, and magnesia. The tartrates of potash, soda, and ammo- nia, are not only susceptible of combining to- gether, but also with the other tartrates, so as to form double or triple salts. We may thus easily conceive why the tartrates of potash, soda, and ammonia, do not disturb the so- lutions of iron and manganese; and on the other hand, disturb the solutions of the salts of barytes, strontites, lime, and lead. In the first case, double salts are formed, however small a quantity of tartrate shall have been employed ; in the second, no double salt is formed, unless the tartrate be added in very great excess. The tartrates of lime and barytes are white, pulverulent, and insoluble. Tartrate of strontian, formed by the double decomposition of muriate of strontian and tar- trate of potash, according to Vanquelin, is soluble, crystallizable, and consists of 52-88 strontian and 47-12 acid. That of magnesia forms a gelatinous or gummy mass. Tartrate of potash, formerly called soluble tartar, because much more so than the super- tartrate, crystallizes in oblong squares, bevelled at the extremities. It has a bitterish taste, and is decomposed by heat, as its solution is even by standing some time. It is used as a mild purgative. The supertartrate of potash, already men- tioned at the beginning of this article, is much used as a cooling and gently opening medicine, as well as in several chemical and pharma- ceutical preparations. Mixed with an equal weight of nitre, and projected into a red-hot crucible, it detonates, and forms the white flux ; treated in the same way with half its weight of nitre, it forms the black Jinx ; and simply mixed with nitre in various proportions, it is called raw flux. It is likewise used in dyeing, in hat-making, in gilding, and in other arts. The blanching of the crude tartar is aided by boiling its solution with ^ of pipe clay. According to the analysis of Berzelius, it consists of 70.45 acid + 24.8 potash -f- 4.75 water = 100; or 2 primes acid, = 16.75 70.30 1 potash, = 5.95 24.95 1 water, = 1.125 4. 75 23.825 100.00 CO parts of water dissolve 4 of bitartrate at a boiling heat ; and only 1 at 60 Fahr. It is quite insoluble in alcohol. It becomes very soluble in water, by adding to it one-fifth of its weight of borax ; or even by the addition of boracic acid. It appears by Berzelius, that neutral tartrate of potash, dried in the sun, differs from the bitartrate, in containing no water of crystallization. He states it to be a compound of 58.69 acid + 41.31 potash = 100 ; which afford 155.7 tartrate of lead. Now, 8.375 : 5.95 : : 58.5 : 41.5; which are the equivalent proportions. On considering the great solvent property cf cream of tartar., and that it is even capable of dissolving various oxides, which are insoluble in tartaric acid, as the protoxide of antimony, M. Gay Lussac has recommended it as a use- ful agent in chemical analysis. He thinks that in many cases it acts the part of a single acid. According to this view, tartar emetic would be a compound of the cream-tartar acid, and protoxide of antimony. Cream of tartar generally contains from 3 to 5 per cent of tar- trate of lime, which are in a great measure separated when 8 parts of tartar are boiled with 1 of borax for a few minutes in a suffi- cient quantity of water. The soluble cream of tartar which is obtained by this process is deliquescent ; it dissolves in its own weight of boiling water, at 54.5, and in half its weight of boiling water. Its solution is very imper- fectly decomposed by the sulphuric, nitric, and muriatic acids. 4 parts of tartar and 1 of bo- racic acid form a permanent saline compound, very soluble in water. Alum also increases the solubility of tartar. By saturating the superfluous acid in this supertartrate with soda, a triple salt is formed, which crystallizes in larger regular prisms of eight nearly equal sides, of a bitter taste, efflo- rescent, and soluble in about five parts of water. It consists, according to Vauquelin, of 54 parts tartrate of potash and 46 tartrate of soda ; and was once in much repute as a purgative by the name of Rochelle Salt or sel de Feig- nette. The tartrate of soda is much less soluble than this triple salt, and crystallizes in slender needles or thin plates. The taitrate of ammonia is a very soluble, ACI 102 ACO bitter salt, and crystallizes easily. Its solution is spontaneously decomposable. This too forms, with tartrate of potash, a triple salt, the solution of which yields, by cooling, fine pyramidal or prismatic efflores- cent crystals. Though both the neutral salts that compose it arc bitter, this is not, but has a cooling taste. See SALT. M. Fabroni says, that sulphuric acid being mixed with three parts of boiling water and cream of tartar in excess, gives a fluid which, after being evaporated, cooled, and allowed to deposit undecomposed tartar, sulphate of pot- ash, &c. will not furnish any other deposit, and resembles oil in its appearance. When further evaporated to the consistence of syrup, and again cooled, it solidifies in a mass com- posed of imperfect prismatic crystals, which when dry have something the appearance of camphor. It dissolves rapidly in water, but in alcohol yields its tartaric acid, while acid sulphate of potash is left. On analysis it gave 72 tartaric acid, and 28 sulphate of potash. Glor. de Fisica, vi. 452. ACID (TITANIC). By fusing powdered rutilite with thrice its weight of carbonate of potash, dissolving the compound in muriatic acid, precipitating by caustic ammonia, digest, ing the precipitate for a certain time with hy- drosulphuret of ammonia, and then digesting the solid matter left in weak muriatic acid, Mr. Rose obtains a perfectly white oxide of titanium, which is not attacked by acids, but which becomes red by touching moistened litmus. As it acts with alkalis precisely as an acid, Mr. Rose calls it titanic acid, It is said to consist of titanium 66-05 oxygen 33.95 ; whence if, like the other metallic acids, this be supposed to contain 3 atoms of oxygen, the atomic weight of the metal will be 5,83, or possibly C. Acid titanate of potash consists of, titanic acid . . 32.33 potash . . . 17.77 Acid titanate of soda, titanic acid . . 83.15 } lnn soda .... 16.85 $ 10U * Sulpho-titanic acid consists of, titanic acid . . 76.67] ;. sulphuric acid . 7.67 V 100. water . . . . 15.66 ( Oxalo-titanic acid of; titanic' acid 74.1 ; oxalic acid 10.4; water 15.5. Sulphuret of titanium consists of titanium 49.17; sulphur 50. 83. Protochloride of titanium consists of tita- nium 6 ; chlorine 3.6. Perchloride of titanium consists of titanium 6.66; chlorine 7.94. Annaks de Chim. xxiii. 353. Annals of Phil. N. S. ix. 18. ACID (TUNGSTOUS). What has been thus called appears to be an oxide of TUNG- STEN. ACID (TUNGSTIC) has been found only in two minerals ; one of which, formerly called tungsten, is a tungstate of lime, and is very rare ; the other more common, is composed of tungstic acid, oxide of iron, and a little oxide of manganese. The acid is separated from the latter in the following way. The wolfram cleared from its siliceous gangue, and pul- verised, is heated in a matrass with five or six times its weight of muriatic acid, for half an hour. The oxides of iron and manganese be- ing thus dissolved, we obtain the tungstic acid under the form of a yellow powder. After washing it repeatedly with water, it is then digested in an excess of liquid ammonia, heated, which dissolves it completely. The liquor is filtered and evaporated to dryness in a capsule. The dry residue being ignited, the ammonia flies off, and pure tungstic acid re- mains. If the whole of the wolfram has not been decomposed in this operation, it must be subjected to the muriatic acid again. It is tasteless, and does not affect vegetable colours. The tungstates of the alkalis and magnesia are soluble and crystallizable ; the other earthy ones are insoluble, as well as those of the metallic oxides. The acid is composed of 100 parts metallic tungsten, and 25 or 26.4 oxygen. ACID (URIC). The same with LITHIC ACID ; which see. ACID (ZOONIC). In the liquid pro- cured by distillation from animal substances, which had been supposed to contain only car- bonate of ammonia and an oil, Berthollet ima- gined he had discovered a peculiar acid, to which he gave the name of zoonic. Thenard, however, has demonstrated that it is merely acetic acid combined with animal matter. ACIDIFIABLE. Capable of being con- verted into an acid by an acidifying principle. (See ACID.) Substances possessing this pro- perty are called radicals, or acidljiaUe bases. ACIDIFYING PRINCIPLE. See re- marks on this subject, in the general article ACID. ACIDIMETRY. The measurement of the strength of acids. This is effected by sa- turating a given weight of them with an alka- line base ; the quantity of which requisite for the purpose is the measure of their power. ACIDULE. A term applied by the French chemists to those salts in which the base is combined with such an excess of acid, that they manifestly exhibit acid properties ; such as the supertartrate of potash. ACONITA. A poisonous vegetable prin- ciple, probably alkaline, supposed to exist in the aconiium napclhis, or wolfsbane. In some British journals it is stated that Mr. Brandes had procured this alkaline principle. But I observe in his translation of my Dictionary into the German language, that he refers the point to the researches of M. Peschier of Geneva, who has not hitherto made it di- ACT 103 ADI stinctly out. Bucholz analyzed the herb aco- nite, and found the following constituents in 20 ounces: oz. dr. gr. Water and volatile matter . . 16 6 Fibrous matter . . *-. ; ,.-v 130 Green resin 1 50 Vegetable albumen (FJfanzenei- weiss) 3 55 Extractive with various acetates and muriates 4 60 iummy matter 6 tfalate and citrate of lime , . I 56 20 2 30 The distilled water of aconite, though smell- ing rank of the plant, is not poisonous. The noxious principle is therefore not volatile. The details of the analysis have not reached this country. ACROSPIRE. The plumula is that part of the embryon of a plant destined to become the stem, and which bears the cotylidons. Ac- cording to Grew, the acrospire is the plumula of barley developed by germination. It is sometimes named plantula. ACTINOLITE. Strahlsleln of Werner. Amphibole Actinote hexaedi e of Hauy. There are three varieties of this mineral ; the crys- tallized, the asbestous, and the glassy. 1st, Crystallized actinolite. Colour leek- green, and green of darker shades. It crys- tallizes in long oblique hexaedral prisms, with irregular terminations. Crystals fre- quently striated lengthwise, sometimes acicu- lar. Its lustre is shining. It is translucent. Occasionally it is found in silky fibres. Its sp. gr. varies from 3.0 to 3.3. Fracture usually radiated ; sometimes it is foliated with an in- distinct twofold cleavage. It scratches glass. 2d, Asbestous actinolite. Colours green, verging on grey and brown, and smalt-blue. Massive and in elastic capillary crystals, which are grouped in wedge-shaped, radiated, or pro- miscuous masses. Internal lustre pearly. Melts before the blowpipe into a dark glass. Fracture intermediate between fibrous and narrow ra- diated. Fragments wedge-shaped. Opaque. Soft. Tough but sectile. Sp. gr. 2.7 to 2.9. 3d, Glassy actinolite. Colours, mountain- green, and emerald-green. In thin six-sided needle r form crystals. Has cross rents. Sp. gr. from 3.0 to 3.2. The composition of actinolite is very differently stated by different analysts. Laugier's results with glassy ac- tinolite are the following, and they approximate to those of Vauquelin on asbestous actinolite; silica 50, lime 9.75, magnesia 19.25, oxide of iron 11, alumina 0.75, oxide of manganese 0.5, oxide of chromium 3, potash 0.5, moisture 5, loss 0.25. 28.2 of alumina and 3.84 of tung- stic acid were found in 100 parts of asbestous actinolite from Cornwall. Actinolite is found chiefly in primitive dis- tricts, with a magnesian basis. It accompanies talc, and some micaceous rocks. Its principal localities are Zillerthal, in the Tyrol, Mont St. Gothard, near Saltzburg, in Saxony ; in Nor- way, and in Piedmont. In Great Britain, it is found in Cornwall and Wales ; and in Glen Elg, the isles of Lewis and Sky. It is never found in secondary mountains. ADAMANT. See DIAMOND. ADHESION. See COHESION. ADHESIVE SLATE. See SLATE. ADI POCERE. The attention of chemists has been much excited by the spontaneous con- version of animal matter into a substance considerably resembling spermaceti. The fact has long been well known, and is said to have been mentioned in the works of Lord Bacon, though I have not seen the passage. On the occasion of the removal of a very great number of human bodies from the ancient burying- place des Innocens at Paris, facts of this nature were observed in the most striking manner. Fourcroy maybe called the scientiiic discoverer of this peculiar matter, as well as the sapo- naceous ammoniacal substance contained in bodies abandoned to spontaneous destruction in large masses. This chemist read a memoir on the subject in the year 1789 to the Royal Academy of Sciences, from which I shall ab- stract the general contents. At the time of clearing the before men- tioned burying-place, certain philosophers were specially charged to direct the precautions re- quisite for securing the health of the workmen. A new and singular objvct of research pre- sented itself, which had been necessarily unknown to preceding chemists. It was im- possible to foretell what might be the contents of a soil overloaded for successive ages with bodies resigned to the putrefactive process. This spot differed from common burying- grounds, where each individual object is sur- rounded by a portion of the soil. It was the buryirsg-ground of a large district, wherein successive generations of the inhabitants had been deposited for upwards of three centuries. It could not be foreseen that the entire de- composition might be retarded for more than forty years ; neither was there any reason to suspect that any remarkable difference would arise from the singularity of situation. The remains of the human bodies immersed in this mass of putrescence were found in three different states, according to the time they had been buried, the place they occupied, and their relative situations with regard to each other. The most ancient were simply portions of bones, irregularly dispersed in the soil, which had been frequently disturbed. A second state, in certain bodies which had always been insulated, exhibited the skin, the muscles, tendons, and aponeuroses, dry, brktle, hard, more or less grey, and similar to what are called mummies in certain caverns where this change has been observed, as in the catacombs at Rome, and the vault of the Cordeliers at Tholouse. ADI 104 ADI The third and most singular state of these soft parts was observed in the bodies which filled the common graves or repositories. By this appellation are understood cavities of thirty feet in depth, and twenty on each side, which were dug in the burying-ground of the Inno- cents, and were appropriated to contain the bodies of the poor ; which were placed hi very close rows, each in its proper wooden bier. The necessity for disposing a great number, obliged the men charged with this employment to arrange them so near each other, that these cavities might be considered when filled as an entire mass of human bodies separated only by two planks of about half an inch thick. Each cavity contained between one thousand and fifteen hundred. When one common grave of this magnitude was filled, a covering of about one foot deep of earth was laid upon it, and another excavation of the same sort was made at some distance. Each grave remained open about three years, which was the time re- quired to fill it. According to the urgency of circumstances, the graves were again made on the same spot after an interval of time, not less than fifteen years, nor more than thirty. Ex- perience had taught the workmen, that this time was not sufficient for the entire destruction of the bodies, and had shown them the pro- gressive changes which form the object of M. Fourcroy's memoir. The first of these large graves opened in the presence of this chemist had been closed for fifteen years. The coffins were in good pre- servation, but a little settled, and the wood (I suppose deal) had a yellow tinge. When the covers of several were taken off, the bodies were observed at the bottom, leaving a con- siderable distance between their surface and the cover, and flattened as if they had suffered a strong compression. The linen which had covered them was slightly adherent to the bodies ; and, with the form of the different regions, exhibited, on removing the linen, nothing but irregular masses of a soft ductile matter of a grey- white colour. These masses environed the bones on all sides, which had no solidity, but broke by any sudden pressure. The appearance of this matter, its obvious composition and its softness, resembled com- mon white cheese ; and the resemblance was more striking from the print which the threads of the linen had made upon its surface. This white substance yielded to the touch, and became soft when rubbed for a time between the fingers. No very offensive smell was emitted from these bodies. The novelty and singularity of the spectacle, and the example of the grave- diggers, dispelled every idea either of disgust or apprehension. These men asserted that they never found this matter, by them called gras (fat), in bodies interred alone; but that the accumulated bodies of the common graves pnjy were subject to this change. On a very attentive examination of a number of bodies passed to this state, M. Fourcroy remarked that the conversion appeared in different stages of advancement, so that, in various bodies, the fibrous texture and colour, more or less red, were discernible within the fatty matter ; that the masses covering the bones were entirely of the same nature, offering indistinctly in all the regions a grey substance, for the most part soft and ductile, sometimes dry, always easy to be separated in porous fragments, penetrated with cavities, and no longer exhibiting any traces of membranes, muscles, tendons, vessels, or nerves. On the first inspection of these white masses, it might have been concluded that they were simply the cellular tissue, the compartments and vesicles of which they very well represented. By examining this substance in the different regions of the body, it was found that the skin is particularly disposed to this remarkable alteration. It was afterwards perceived that the ligaments and tendons no longer existed, or at least had lost their tenacity ; so that the bones were entirely unsupported, and left to the action of their own weight. Whence their relative places were preserved in a certain de- gree by mere juxtaposition; the least effort being sufficient to separate them. The grave- diggers availed themselves of this circumstance in the removal of the bodies. For they rolled them up from head to feet, and by that means separated from each other the extremities of the bones, which had formerly been articulated. In all those bodies which were changed into the fatty matter, the abdominal cavity had disappeared. The teguments and muscles of this, region being converted into the white matter, like the other soft parts, had subsided upon the vertebral column, and were so flat- tened as to leave no place for the viscera ; and accordingly there was scarcely ever any trace observed in the almost obliterated cavity. This observation was for a long time matter of astonishment to the investigators. In vain did they seek, in the greater number of bodies, the place and substance of the stomach, the intestines, the bladder, and even the liver, the spleen, the kidneys, and the matrix in females. All these viscera were confounded together, and for the most part no traces cf them were left. Sometimes only certain irregular masses were found, of the same nature as the white matter, of different bulks, from that of a nut to two or three inches in diameter, in the regions of the liver or of the spleen. The thorax likewise offered an assemblage of facts no less singular and interesting. The external part of this cavity was flattened and compressed like the rest of the organs; the ribs, spontaneously luxated in their articula- tions with the vertebra, were settled upon the dorsal column ; their arched part left only a small space on each side between them and the vertebra. The pleura, the mediastineB, ADI 105 ADI the large vessels, the aspera arteria, and even the lungs and the heart, were no longer dis- tinguishable ; but for the most part had en- tirely disappeared, and in their place nothing was seen but some parcels of the fatty sub- stance. In this case, the matter which was the product of decomposition of the viscera, charged with blood and various humours, differs from that of the surface of the body, and the long bones, in the red or brown colour possessed by the former. Sometimes the observers found in the thorax a mass irre- gularly rounded, of the same nature as the latter, which appeared to them to have arisen from the fat and fibrous substance of the heart. They supposed that this mass, not constantly found in all the subjects, owed its existence to a superabundance of fat in this viscus, where it was found. For the general observation presented itself, that, in similar circumstances, the fat parts undergo this conversion more evi- dently than the others, and afford a larger quantity of the white matter. The external region in females exhibited the glandular and adipose mass of the breasts converted into the fatty matter, very white and very homogeneous. The head was, as has already been re- marked, environed with the fatty matter ; the face was no longer distinguishable in the greatest number of subjects ; the mouth dis- organized, exhibited neither tongue nor pa- late ; and the jaws, luxated and more or less displaced, were environed with irregular layers of the white matter. Some pieces of the same matter usually occupied the place of the parts situated in the mouth ; the cartilages of the nose participated in the general alteration of the skin ; the orbits, instead of eyes, contained white masses ; the ears were equally disor- ganized; and the hairy scalp, having under- gone a similar alteration to that of the other organs, still retained the hair. M. Fourcroy remarks incidentally, that the hair appears to resist every alteration much longer than any other part of the body. The cranium con- stantly contained the brain contracted in bulk ; blackish at the surface^ and absolutely changed like the other organs. In a great number of subjects which were examined, this viscus was never found wanting, and it was always in the above-mentioned state; which proves that the substance of the brain is greatly disposed to be converted into the fat matter. Such was the state of the bodies found in the burial-ground des Innocens. Its modifi- cations were also various. Its consistence in bodies lately changed, that is to say, from three to five years, was soft and very ductile, containing a great quantity of water. In other subjects converted into this matter for a long time, such as those which occupied the cavities which had been closed thirty or forty years, this matter is drier, more brittle, and in , denser flakes. In several which were depo- sited in dry earth, various portions of the fatty matter had become semitransparent The aspect, the granulated texture, and brittleness of this dried matter, bore a considerable re- semblance to wax. The period of the formation of this sub- stance had likewise an influence on its pro- perties. In general, all that had been formed for a long time was white, uniform, and contained no foreign substance, or fibrous remain:; ; such, in particular, was that afforded by the skin of the extremities. On the con- trary, in bodies recently changed, the fatty matter was neither so uniform nor so pure as in the former ; but it was still found to con- tain portions of muscles, tendons, and liga- ments, the texture of which, though already altered and changed in its colour, was still distinguishable. Accordingly, as the conver- sion was more or less advanced, these fibrous remains were more or less penetrated with the fatty matter, interposed as it were between the interstices of the fibres. This observation shows, that it is not merely the fat which is thus changed, as was natural enough to think at first sight. Other facts confirm this asser- tion. The skin, as has been remarked, be- comes easily converted into very pure white matter, as does likewise the brain, neither of which has been considered by anatomists to be fat. It is true, nevsrtheless, that the unc- tuous parts, and bodies charged with fat, appear more easily and speedily to pass to the state under consideration. This was seen in the marrow, which occupied the cavities of the longer bones. And again, it is not to be sup- posed but that the greater part of these bodies had been emaciated by the illness which ter- minated their lives ; notwithstanding which, they were all absolutely turned into this fatty substance. An experiment made by M. Poulletier de la Salle, and Fourcroy likewise, evinced that a conversion does not take place in the fat alone. M. Poulletier had suspended in his laboratory a small piece of the human liver, to observe what would arise to it by the con- tact of the air. It partly putrefied, without, however, emitting any very noisome smell. Larvae of the dermestes and bruchus attacked and penetrated it in various directions : at last it became dry, and after more than ten years' suspension, it was converted into a white friable substance resembling dried agaric, which might have been taken for an earthy substance. In this state it had no perceptible smell. M. Poulletier was desirous of knowing the state of this animal matter, and experiment soon convinced him and M. F. that it was very far from being in the state of an earth. It melted by heat, and exhaled in the form of vapour, which had the smell of a very fetid fat ; spirit of wine separated a concrescible oil, which appeared to possess all the properties of spermaceti. Each of the three alkalis con- ADI 106 ADI verted it into soap; and, in a word, it ex- hibited all the properties of the fatly matter of the burial-ground of the Innocents exposed for several months to the air. Here then was a glandular organ, which in the midst of the atmosphere had undergone a change similar to that of the bodies in the burying-place ; and this fact sufficiently shows, that an animal substance, which is very far from being of the nature of grease, may be totally converted into this fatty substance. Among the modifications of this remark- able substance in the burying-ground before mentioned, it was observed that the dry, friable, and brittle matter, was most com- monly found near the surface of the earth, and the soft ductile matter at a greater depth. M. Fourcroy remarks, that this dry matter did not differ from the other merely in containing less water, but likewise by the volatilization of one of its principles. The grave-diggers assert, that near three years are required to convert a body into this fatty substance. But Dr. Gibbes of Oxford found, that lean beef secured in a running stream was converted into this fatty matter at the end of a month. He judges from facts, that running water is most favourable to this process. He took three lean pieces of mutton, and poured on each a quantity of the three common mineral acids. At the end of three days, each was much changed: that in the nitric acid was very soft, and converted into the fatty matter ; that in the muriatic acid was not in that time so much altered ; the sul- phuric acid had turned the other black. M. Lavoisier thinks that this process may here- after prove of great use in society. It is not easy to point out what animal substance, or what situation, might be the best adapted for an undertaking of this kind. M. L. points out fecal matters; but I have not heard of any conversion having taken place in these animal remains, similar to that of the foregoing. The result of M. Fourcroy's inquiries into the ordinary changes of bodies recently de- posited in the earth, was not very extensive. The grave-diggers informed him, that those bodies interred do not perceptibly change colour for the first seven or eight days ; that the putrid process disengages elastic fluid, which inflates the abdomen, and at length bursts it; that this event instantly causes vertigo, faintness, and nausea in svfch persons as unfortunately are within a certain distance of the scene where it takes place; but that when the object of Its action is nearer, a sud- den privation of sense, and frequently death, is the consequence. These men are taught by experience, that no immediate danger is to be feared from the disgusting business they are engaged in, excepting at this period, which they regard with the utmost terror. They re- sisted every inducement and persuasion which these philosophers made use of, to prevail on them to assist their researches into the nature of this active and pernicious vapour. M. Four- croy takes occasion from these facts, as well as from the pallid and unwholesome appear- ance of the grave-diggers, to reprobate burials in great towns or their vicinity. Such bodies as are interred alone, in the midst of a great quantity of humid earth, are totally destroyed by passing through the suc- cessive degrees of the ordinary putrefaction ; and this destruction is more speedy, the warmer the temperature. But if these insulated bodies be dry and emaciated ; if the plac'j of deposi- tion be likewise dry, and the locality and other circumstances such, that the earth, so far from receiving moisture from the atmosphere, be- comes still more effectually parched by the solar rays ; the animal juices are volatilized and absorbed, the solids contract and harden, and a peculiar species of mummy is produced. But every circumstance is very different in the common burying-grounds. Heaped together almost in contact, the influence of external bodies affects them scarcely at all, and they become abandoned to a peculiar disorganization, which destroys their texture, and produces the new and most permanent state of combination here described. From various observations, which I do not here extract, it was found, that this fatty matter was capable of enduring in these burying-places for thirty or forty years, and is at length corroded and carried off by the aqueous putrid humidity which there abounds. Among other interesting facts afforded by the chemical examination of this substance, are the following from experiments by M. Fourcroy. 1. This substance is fused at a less degree of heat than that of boiling water, and may be purified by pressure through a cloth, which disengages a portion of fibrous and bony mat- ter. 2. The process of destructive distillation by a very graduated heat was begun, but not completed on account of its tediousness, and the little promise of advantage it afforded. The products which came over were water charged with volatile alkali, a fat oil, concrete volatile alkali, and no elastic fluid during the time the operation was continued. 3. Frag- ments of the fatty matter exposed to the air during the hot and dry summer of 1786 be- came dry, brittle, and almost pulverulent at the surface. On a careful examination, certain portions were observed to be semitransparent, and more brittle than the rest. These pos- sessed all the apparent properties of wax, and did not afford volatile alkali by distillation. 4. With water this fatty matter exhibited all the appearances of soap, and afforded a strong lather. The dried substance did not form the saponaceous combination with the same facility or perfection as that which was recent. About two-thirds of this dried matter separated from the water by cooling, and proved to be the semitransparent substance resembling wax. ADI 107 ADI This was taken from the surface of the soapy liquor, which being then passed through the filter, left a white soft shining matter, which was fusible and combustible. 5. Attempts were made to ascertain the quantity of volatile alkali in this substance, by the application of lime, and of the fixed alkalis, but without success: for it was difficult to collect and appreciate the first portions which escaped, and likewise to disengage the last portions. The caustic volatile alkali, with the assistance of a gentle heat, dissolved the fatty matter, and the solution became perfectly clear and transparent at the boiling temperature of the mixture, which was at 185 F. 6. Sulphuric acid, of the specific gravity of 2.0, was poured upon six times its weight of the fatty matter, and mixed by agitation. Heat was produced, and a gas or effluvium of the most insupportable putrescence was emitted, which infected the air of an extensive laboratory for several days. M. Fourcroy says, that the smell cannot be described, but that it is one of the most horrid and repulsive that can be imagined. It did not, however, produce any indisposition either in himself or his assistants. By dilution with water, and the ordinary processes of evaporation and cooling, properly repeated, the sulphates of ammonia and of lime were obtained. A substance was separated from the liquor, which appeared to be the waxy matter, somewhat altered by the action of the acid. 7. The nitrous and muriatic acids were also applied, and afforded phenomena worthy of remark, but which for the sake of conciseness are here omitted. 8. Alcohol does not act on this matter at the ordinary temperature of the air. But by boiling it dissolves one-third of its own weight, which is almost totally separable by cooling as low as 55. The alcohol, after this process, affords by evaporation a portion of that waxy matter which is separable by acids, and is therefore the only portion soluble in cold alcohol. The quantity of fatty matter operated on was 4 ounces, or 2304 grains, of which the boiling spirit took up the whole ex- cept 26 grains, which proved to be a mixture of 20 grains of ammoniacal soap, and G or 8 grains of the phosphates of soda and of lime. From this experiment, which was three times repeated with similar results, it appears that alcohol is well suited to afford an analysis of the fatty matter. It does not dissolve the neutral salts; when cold, it dissolves that portion of concrete animal oil from which the volatile alkali had flown off; and when heated, it dissolves the whole of the truly saponaceous matter, which is afterwards completely separated by cooling. And accordingly it was found, that a thin plate of the fatty matter, which had lost nearly the whole of its volatile alkali, by exposure to the air for three years, was almost totally dissolved by the cold alcohol. The concrete oily or waxy substance obtained in these experiments constitutes the leading ob- ject of research, as being the peculiar substance with which the other well known matters are combined. It separates spontaneously by the action of the air, as well as by that of acids. These last separate it in a state of greater purity, the less disposed the acid may be to operate in the way of combustion. It is re- quisite, therefore, for this purpose, that the fatty matter should be previously diffused in 12 times its weight of hot water; and the muriatic or acetous acid is preferable to the sulphuric or the nitrous. The colour of the waxy matter is greyish ; and though exposure to the air, and also the action of the oxygenated muriatic acid did produce an apparent white- ness, it nevertheless disappeared by subsequent fusion. No method was discovered by which it could be permanently bleached. The nature of this wax or fat is different from that of any other known substance of the like kind. When slowly cooled after fusion, its texture appears crystalline or shivery, like spermaceti ; but a speedy cooling gives it a semitransparency resembling wax. Upon the whole, nevertheless, it seems to approach more nearly to the former than to the latter of these bodies. It has less smell than spermaceti, and melts at 127 F. ; Dr. Bostock says 92". Spermaceti requires G more of heat to fuse it (according to Dr. Bostock 20). The sper- maceti did not so speedily become brittle by cooling as the adipocere. One ounce of alcohol of the strength between 39 and 40 degrees of Baume's aerometer, dissolved when boiling hot 12 gros of this substance, but the same quantity in like circumstances dissolved only 30 or 36 grains of spermaceti. The separation of these matters was also remarkably different, the spermaceti being more speedily deposited, and in a much more regular and crystalline form. Ammonia dissolves with singular facility, and even in the cold, this concrete oil separated from the fatty matter ; and by heat it forms a transparent solution, which is a true soap. But no excess of ammonia can produce such an effect with spermaceti. M. Fourcroy concludes his memoir with some speculations on the change to which animal substances in peculiar circumstances are subject. In the modern chemistry, soft animal matters are considered as a composition of the oxides of hydrogen and carbonated azote, more complicated than those of vegetable mat- ters, and therefore more incessantly tending to alteration. If then the carbon be conceived to unite with the oxygen, either of the water which is present, or of the other animal mat- ters, and thus escape in large quantities in the form of carbonic acid gas, we shall perceive the reason why this conversion is attended with so great a loss of weight, namely, about nine-tenths of the whole. The azote, a prin^ ciple so abundant in animal matters, will form ammonia by combining with the hydrogen ; part of this will escape in the vaporous form, ADI 108 ADI and the rest will remain fixed in the fatty matter. The residue of the animal matters de- prived of a great part of their carbon, of their oxygen, and the whole of their azote, will consist of a much greater proportion of hy- drogen, together with carbon and a minute quantity of oxygen. This, according to the theory of M. Fourcroy, constitutes the waxy matter, or adipocere, which, in combina- tion with ammonia, forms the animal soap, into which the dead bodies are thus con- verted. Muscular fibre, macerated in dilute nitric acid, and afterwards well washed in warm water, affords pure adipocere, of a light yellow colour, nearly of the consistence of tallow, of a homogeneous texture, and of course free from ammonia. This is the mode in which it is now commonly procured for chemical experiment This curious substance has been more re- cently examined by Chevreul. He found it composed of a small quantity of ammonia, potash, and lime, united to much margarine, and to a very little of another fatty matter different from that. Weak muriatic acid seizes the three alkaline bases. On treating the residue with a solution of potash, the mar- garine is precipitated in the form of a pearly substance, while the other fat remains dissolved. Fourcroy being of opinion that the fatty mat- ter of animal carcases, the substance of biliary calculi, and spermaceti, were nearly identical, gave them the same name of adipocere ; but it appears from the researches of M. Chevreul that these substances are very different from each other. In the Philosophical Transactions for 1813 there is a very interesting paper on the above subject by Sir E. Home and Mr. Brande. He adduces many curious facts to prove that adipocere is formed by an incipient and incom- plete putrefaction. Mary Howard, aged 44, died on the 12th May 1790, and was buried in a grave ten feet deep at the east end of Shoreditch church-yard, ten feet to the east of the great common sewer, which runs from north to south, and has always a current of water in it, the usual level of which is eight feet below the level of the ground, and two feet above the level of the coffins in the graves. In August 1811 the body was taken up, with some others buried near it, for the purpose of building a vault, and the flesh in all of them was converted into adipocere or spermaceti. At the full and new moon the tide raises water into the graves, which at other times are dry. To explain the extraordinary quantities of fat or adipocere formed by animals of a certain intestinal construction, Sir E. observes, that the current of water which passes through their colon, while the loculated lateral parts are full of solid matter, places the solid contents in somewhat similar circumstances to dead bodies in the banks of a common sewer. The circumstance of ambergris, which con- tains CO per cent, of fat, being found in im- mense quantities in the lower intestines of the spermaceti whales, and never higher up than seven feet from the anus, is an undeniable proof of fat being formed in the intestines; and as ambergris is only met with in whales out of health, it is most probably collected there from the absorbents, under the influence of disease, not acting so as to take it into the constituuon. In the human colon, solid masses of fat are sometimes met with in a diseased state of that canal, and are called scylala. A description and analysis by me of a mass of ambergris, extracted in Perthshire from the rectum of a living woman, were published in a London Medical Journal in September 1817' There is a case communicated by Dr. Babing- ton, of fat formed in the intestines of a girl four and a half years old, and passing off by stool. Mr. Brande found, on the suggestion of Sir E. Home, that muscle digested in bile, is convertible into fat, at the temperature of about 100. If the substance, however, pass rapidly into putrefaction, no fat is formed. Faeces voided by a gouty gentleman after six days constipation, yielded, on infusion in water, a fatty film. This process of forming fat in the lower intestines by means of biie, throws considerable light upon the nourishment de- rived from clysters, a fact well ascertained, but which could not be explained. It also accounts for the wasting of the body which so invariably attends all complaints of the lower bowels. It accounts too for all the varieties in the turns of the colon, which we meet with in so great a degree in different animals. This property of the bile explains likewise the formation of fatty concretions in the gall bladder so commonly met with, and which, from these experiments, appear to be produced by the action of the bile on the mucus secreted in the gall bladder; and it enables us to understand how want of the gall bladder in children, from mal-for- mation, is attended with excessive leanness, notwithstanding a great appetite, and leads to an early death. Fat thus appears to be formed in the intestines, and from thence re- ceived into the circulation, and deposited in almost every part of the body. And as there appears to be no direct channels by which any superabundance of it can be thrown out of the body, whenever its supply exceeds the con- sumption, its accumulation becomes a disease, and often a very distressing one. See BILIARY CONCRETIONS, MARGARINE, and INTES- TINAL CONCRETIONS. ADIT, in mining, is a subterraneous pass- age slightly inclined, about six feet high, and two or three feet wide, begun at the bottom of a neighbouring valley, and continued up to the vein, for the purpose of carrying out the minerals and drawing off the water. If the mine require draining by a steam-engine from a greater depth, the water need be raised AEIl 109 AGA only to the level of the adit. There is a good account of the Cornish adits, by Mr. W. Philips. Trans. Geol. Soc. vol. ii.; and of adits in general, article Galerie, Brogniart's Mineralogy, vol. ii. ADOPTER, a vessel with two necks placed between a retort and a receiver, and serving to increase the length of the neck of the former. See LABORATORY. ADULARIA. See FELSPAR. AERATED ALKALINE WATER. See ACID (CARBONIC). AERIAL ACID. See ACID (CARBO- NIC). AEROLITE, or METEORIC STONE. See METEORITE. AEROMETER. The name given by Dr. M. Hall to an ingenious instrument of his invention for making the necessary cor- rections in pneumatic experiments, to ascer- tain the mean bulk of the gases. It consists of a bulb of glass 4^- cubic inches capacity, blown at the end of a long tube whose capa- city is one cubic inch. This tube is inserted into another tube of nearly equal length, sup- ported on a sole. The first tube is sustained at any height within the second by means or a spring. Five cubic inches of atmospheric air, at a medium pressure and temperature, are to be introduced into the bulb and tube, of the latter of which it will occupy one-half; the other half of this tube, and part of the tube into which it is inserted, are to be occu- pied by the fluid of the pneumatic trough, whether water or mercury. The point of the tube at which the air and fluid meet is to be marked by the figure 5, denoting 5 cubic inches. The upper and lower halves of the tube are each divided into 5 parts, represent- ing tenths of a cubic inch. The external tube has a scale of inches attached. Journal of Science, vol. v. See GAS and APPENDIX. AEROSTATION, a name commonly, but not very correctly, given to the art of raising heavy bodies into the atmosphere, by the buoyancy of heated air, or gases of small specific gravity, enclosed in a bag, which, from being usually of a spheroidal form, is called a balloon. Of all the possible shapes, the globular admits the greatest capacity under the least surface. Hence, of two bags of the same capacity, if one be spherical, and the other of any other shape, the former will con- tain the least quantity of cloth, or the least surface. The spheroidal form is therefore best fitted for aerostation. Varnished lute- string or muslin are employed for the en- velopes. The following table shows the re- lation betwixt the diameters, surfaces, and capacities of spheres : Diameters. Surfaces. Capacities. 1 3.141 0.623 2 12.567 4.188 3 28.274 14.137 Diameters. Surfaces. Capacities. 4 5 10 15 20 25 30 40 50.265 78.54 314.159 706.9 1256.6 1963.5 2827. 5026. 33.51 65.45 523.6 1767.1 4189. 8181. 14137. 33510. Having ascertained by experiment the weight of a square foot of the varnished cloth, we find, by inspection in the above table, a multiplier whence we readily compute the to- tal weight of the balloon. A cubic foot of atmospheric air weighs 527 g* and a cubic foot of hydrogen about 40. But as the gas employed to fill balloons is never pure, we must estimate its weight at something more. And perhaps, taking every thing into account, we shall find it a convenient and sufficiently precise rule for aerostation, to copsider every cubic foot of included gas, to have by itself a buoyancy of fully one ounce avoirdupois. Hence a balloon of 10 feet diameter will have an ascensional force of fully 524 oz. or 331bs. minus the weight of the 314 superficial feet of cloth ; and one of 30 feet diameter, a buoy- ancy of fully 14137 oz., or nearly 890 Ibs. minus the weight of the 2827 feet of cloth. On this calculation no allowance need be made for the seams of the balloon. See the article VARNISH. jETITES, or EAGLE STONE, is a name that has been given to a kind of hollo wgeodes of oxide of iron, often mixed with a larger or smaller quantity of silex and alumina, con- taining in their cavity some concretions, which rattle on shaking the stone. It is of a dull pale colour, composed of concentric layers of various magnitudes, of an oval or polygonal form, and often polished. Eagles were said to carry them to their nests, whence their name ; and superstition formerly ascribed won- derful virtues to them. AFFINITY (CHEMICAL). See AT- TRACTION (CHEMICAL). AGALMATOLITE. See BILDSTEIN. AGARICUS; The mushroom, a genus of the order Fungi. Mushrooms appear to approach nearer to the nature of animal matter than any other productions of the vegetable kingdom, as, beside hydrogen, oxygen, and carbon, they contain a considerable portion of nitrogen, and yield ammonia by distillation. Prof. Proust has likewise discovered in them the benzoic acid, and phosphate of lime. A few of the species are eaten in this country, but many are recorded to have pro- duced poisonous effects. Perhaps it is of im- portance, that they should be fresh, thoroughly dressed, and not of a coriaceous texture. Our ketchup is made by sprinkling mushrooms with salt, and letting them stand till great AGA 110 AGA part is resolved into a brown liquor, which is then boiled up with spices. In pharmacy two species of boletus have formerly been used under the name of aga- ric. The B. pint laricis, or male agaric of the shops, was given as a purgative, either in substance, or in an extract made with vinegar, wine, or an alkaline solution: and the B. igniarius, spunk, or touchwood, called female agaric, was applied externally as a styptic, even after amputations. For this purpose the soft inner substance was taken, and beaten with a hammer to render it still softer. That of the oak was preferred. The mushrooms, remarkable for the quick- ness of their growth and decay, as well as for the foetor attending their spontaneous decom- position, were unaccountably neglected by analytical chemists, though capable of reward- ing their trouble, as is evinced by the recent investigations and discoveries of MM. Vau- quelin and Braconnot. The insoluble fun- gous portion of the mushroom, though it re- sembles woody fibre in some respects, yet being less soluble than it in alkalis, and yielding a nutritive food, is evidently a peculiar product, to which accordingly the name of fungin has been given. Two new vegetable acids, the boletic and fungic, were also fruits of these researches. 1. Agaricus campestris, an ordinary article of food, analyzed by Vauquelin, gave the following constituents: 1. Adipocere. On expressing the juice of the agaric, and sub- jecting the remainder to the action of boiling alcohol, a fatty matter is extracted, which falls down in white flakes as the alcohol cools. It has a dirty white colour, a fatty feel like spermaceti, and, exposed to heat, soon melts, and then exhales the odour of grease ; 2. An oily matter ; 3. Vegetable albumen ; 4. The sugar of mushrooms; 5. An animal matter soluble in water and alcohol : on being heated it evolves the odour of roasting meat, like os- mazome ; 6. An animal matter not soluble in alcohol ; 7- Fungin ; 8. Acetate of potash. 2. Agaricus volvaceus afforded Braconnot fungin, gelatin, vegetable albumen, much phosphate of potash, some acetate of potash, sugar of mushrooms, a brown oil, adipocere, wax, a very fugaceous deleterious matter, un- combined acid, supposed to be the acetic, benzoic acid, muriate of potash, and a deal of water ; in all 14 ingredients. 3. Agaricus acris, or piperatus, was found by Braconnot, after a minute analysis, to contain nearly the same ingredients as the preceding, without the wax and benzoic acid, but with more adipocere. 4. Agaricus stypticus. From twenty parts of this Braconnot obtained of resin and adi- pocere 1.8, fungin 16.7, of an unknown ge- latinous substance, a potash salt, and a fuga- ceous acrid principle, 1.5. 5. Agaricut bulbosu*, was examined by Vauquelin, who found the following consti- tuents ; an animal matter insoluble in alco- hol, osmazome, a soft fatty matter of a yellow colour and acrid taste, an acid salt, (not a phosphate). The insoluble substance of the agaric yielded an acid by distillation. In OrSla's Toxicology several instances are de- tailed of the fatal effects of this species of mushroom on the human body. Dogs were killed within 24 hours by small quantities of it in substance, and also by its watery and alcoholic infusions ; but water distilled from it was not injurious. It is curious that the animals experienced little inconvenience after swallowing it, during the first ten hours; stupor, cholera, convulsions, and painful cramps are the usual symptoms of the poison in men. The best remedy is an emetic. 6. Agaricus iheogolus. In this Vauquelin found sugar of mushrooms, osmazome, a bitter acrid fatty matter, an animal matter not soluble in alcohol, a salt containing a vegetable acid. 7. Agaricus muscarius. Vauquelin's ana- lysis of this species is as follows : The two animal matters of the last agaric, a fatty matter, sulphate, phosphate, and muriate of potash, a volatile acid from the insoluble matter. The following account from Orfila of the effects of this species on the animal economy is interesting. Several French sol- diers ate, at two leagues from Polosck in Russia, mushrooms of the above kind. Four of them, of a robust constitution, who con- ceived themselves proof against the conse- quences under which their feebler companions were beginning to suffer, refused obstinately to take an emetic. In the evening the follow- ing symptoms appeared : Anxiety, sense of suffocation, ardent thirst, intense griping pains, a small and irregular pulse, universal cold sweats, changed expression of countenance, violet tint of the nose and lips, general tremb- ling, fetid stools. These symptoms becoming worse, they were carried to the hospital. Cold- ness and livid colour of the limbs, a dreadful delirium, and acute pains, accompanied them to the last moment. One of them sunk a few hours after his admission into the hospital ; the three others had the same fate in the course of the night. On opening their dead bodies, the stomach and intestines displayed large spots of inflammation and gangrene; and putrefaction seemed advancing very rapidly. AGARICUS MINERALIS, the mountain milk, or mountain meal of the Germans, is one of the purest of the native carbonates of lime, found chiefly in the clefts of rocks, and at the bottom of some lakes, in a loose or semi-indurated form. It has been used in- ternally in haemorrhages, strangury, gravel, and dysenteries ; and externally as an appli- cation to old ulcers, and weak and watery eyes. M. Fabroni calls by the name of mineral agaric, or fossil meal, a stone of a loose con- AGA 111 AGR sistence found in Tuscany in considerable abundance, of which bricks may be made, either with or without the addition of a twen- tieth part of argil, so light as to float in water; and which he supposes the ancients used for makiag their floating bricks. This, however, is very different from the preceding, not being even of the calcareous genus, since it appears, on analysis, to consist of silex 55 parts, magnesia 15, water 14, argil 12, lime 3, iron It Kirwan calls it argillo-murite. AGATE. A mineral, whose basis is cal- cedony, blended with variable proportions of jasper, amethyst, quartz, opal, heliotrope, and cornelian. Ribbon agate, consists of alternate and parallel layers of calcedony with jasper, or quartz, or amethyst. The most beautiful comes from Siberia and Saxony. It occurs in porphyry and gneiss. Brecciutcd agate; a base of amethyst, containing fragments of ribbon agate, constitute this beautiful variety. It is of Saxon origin Fortification agate, is found in nodules of various imitative shapes, imbedded in amygdaloid. This occurs at Oberstein on the Rhine, and in Scotland. On cutting it across, and polishing it, the interior zig-zag parallel lines bear a considerable re- semblance to the plan of a modern fortifi- cation. In the very centre, quartz and ame- thyst are seen in a splintery mass, surrounded by the jasper and calcedony. Mocha stone. Translucent calcedony, containing dark out- lines of arborization, like vegetable filaments, is called Mocha stone, from the place in Arabia where it is chiefly found. These cu- rious appearances were ascribed to deposits of iron or manganese, but more lately they have been thought to arise from mineralized plants of the cryptogamous class. Moss agate, is a calcedony with variously coloured ramifica- tions of a vegetable form, occasionally tra- versed with irregular veins of red jasper. Dr. M'Culloch has recently detected, what Dau- benton merely conjectured, in mocha and moss agates, aquatic conferva?, unaltered both in colour and form, and also coated with iron oxide. JVfosses and lichens have also been observed, along with chlorite, in vegetations. An onyx agate set in a ring, belonging to the Earl of Powis, contains the chrysalis of a moth. Agate is found in most countries, chiefly in trap rocks, and serpentine. Hollow nodules of agate, called geodes, present inte- riorly crystals of quartz, colourless or ame- thystine, having occasionally scattered crystals of stilbite, chabasie, and capillary mesotype. These geodes are very common. Bitumen has been found by M. Patrin in the inside of some of them, among the hills of Dauria, on the right bank of the Chilca. The small geodes of volcanic districts contain water oc- casionally in their cavities. These are chiefly found in insulated blocks of a lava having an earthy fracture. When they are cracked, the liquid escapes by evaporation : it is easily re- stored by plunging them for a little in hot water. Agates are artificially coloured by im- mersion in metallic solutions. Agates were more in demand formerly than at present. They were cut into cups and plates for boxes ; and also into cutlass and sabre handles. They are still cut and polished on a considerable scale and at a moderate price, at Oberstein. The surface to be polished is first coarsely ground by large millstones of a hard reddish sandstone, moved by water. The polish is afterwards given on a wheel of soft wood, moistened and imbued with a fine powder of a hard red tripoli found in the neighbourhood. M. Faujas thinks that this tripoli is produced by the decomposition of the porphyrated rock that serves as a gangue to the agates. The ancients employed agates for making cameos. (See CALCEDONY.) Agate mortars are valu- ed by analytical chemists, for reducing hard minerals to an impalpable powder. For some interesting optical properties of agates, see LIGHT. The oriental agate is almost transparent, and of a vitreous appearance. The occidental is of various colours, and often veined with quartz or jasper. It is mostly found in small pieces covered with a crust, and often running in veins through rocks like flint and petro- silex, from which it does not seem to differ greatly. Agates are most prized, when the internal figure nearly resembles some animal or plant. AGGREGATE. When bodies of the same kind are united, the only consequence is, that one larger body is produced. In this case, the united mass is called an aggregate, and does not differ in its chemical properties from the bodies from which it was originally made. Elementary writers call the smallest parts into which an aggregate can be divided without destroying its chemical properties, integrant parts. Thus the integrant parts of common salt are the smallest parts which can be con- ceived to remain without change; and be- yond these, any further subdivision cannot be made without developing the component parts, namely, the alkali and the acid ; which are still further resolvable into their constituent principles. AGRICULTURE, considered as a de. partment of chemistry, is a subject of vast importance, but hitherto much neglected. When we consider that every change in the arrangements of matter connected with the growth and nourishment of plants ; the com- parative values of their produce as food ; the composition and constitution of soils j and the manner in which lands are enriched by ma- nure, or rendered fertile by the different pro- cesses of cultivation, we shall not hesitate to assign to chemical agriculture a high place among the studies of man. If land be un- productive, and a system of ameliorating it is to be attempted, the sure method of attaining AIR AIR this object is by determining the causes of its sterility, which must necessarily depend upon some defect in the constitution of the soil, which may be easily discovered by chemical analysis. Some lands of good apparent tex- ture are yet eminently barren ; and common observation and common practice afford no means of ascertaining the cause, or of re- moving the effect. The application of che- mical tests in such cases is obvious ; for the soil must contain some noxious principle which may be easily discovered, and probably easily destroyed. Are any of the salts of iron present ? They may be decomposed by lime. Is there an excess of siliceous sand ? The system of improvement must depend on the application of clay and calcareous matter. Is there a defect of calcareous matter ? The remedy is obvious. Is an excess of vegetable matter indicated ? It may be removed by liming, paring, and burning. Is there a defi- ciency of vegetable matter ? It is to be sup- plied by manure. Peat earth is a manure; but there are some varieties of peats which contain so large a quantity of ferruginous matter as to be absolutely poisonous to plants. There has been no question on which more difference of opinion has existed, than that of the state in which manure ought to be ploughed into land ; whether recent, or when it has gone through the process of fermenta- tion. But whoever will refer to the simplest principles of chemistry, cannot entertain a doubt on the subject. As soon as dung be- gins to decompose, it throws off its volatile parts, which are the most valuable and most efficient. Dung which has fermented so as to become a mere soft cohesive mass, has generally lost from one-third to one-half of its most useful constituent elements. See the articles ANALYSIS, MANURE, SOILS, VE- GETATION, and Sir H. Davy's Agricult. Chem. AIR was, till lately, used as the generic name for such invisible and exceedingly rare fluids as possess a very high degree of elas- ticity, and are not condensable into the liquid state by any degree of cold hitherto produced ; but as this term is commonly employed to signify that compound of aeriform fluids which constitutes our atmosphere, it has been deemed advisable to restrict it to this signification, and to employ as the generic term the word GAS, (which see), for the different kinds of air, except what relates to our atmospheric compound. AIR (ATMOSPHERICAL or COM- MON). The immense mass of permanently elastic fluid which surrounds the globe we in- habit, must consist of a general assemblage of every kind of air which can be formed by the various bodies that compose its surface. Most of these, however, are absorbed by wa- ter ; a number of them are decomposed by combination with each other; and some of them are seldom disengaged in considerable quantities by the processes of nature. Hence it is that the lower atmosphere consists chiefly of oxygen and nitrogen, together with mois- ture and the occasional vapours or exhalations of bodies. The upper atmosphere seems to be composed of a large proportion of hydro- gen, a fluid of so much less specific gravity than any other, that it must naturally ascend to the highest place, where, being occasionally set on fire by electricity, it appears to be the cause of the aurora borealis and fire balls. It may easily be understood, that this will only happen on the confines of the respective masses of common atmospherical air, and of the in- flammable air ; that the combustion will ex- tend progressively, though rapidly, in flash- ings from the place where it commences ; and that when by any means a stream of inflam- mable air, in its progress toward the upper atmosphere, is set on fire at one end, its igni- tion may be much more rapid than what hap- pens higher up, where oxygen is wanting, and at the same time more definite in its figure and progression, so as to form the appearance of a fire ball. To the above speculations, it may probably be objected, that the air on the summit of Mont Blanc, and that brought down from still greater heights by M. Gay Lussac, in an aerostatic machine, gave, on analysis, no product of hydrogen. But the lowest esti- mate of the height of luminous meteors, is prodigiously greater than the highest eleva- tions to which man has reached. See COM- BUSTION. That the air of the atmosphere is so trans- parent as to be invisible, except by the blue colour it reflects when in very large masses, as is seen in the sky or region above us, or in viewing extensive landscapes ; that it is without smell, except that of electricity, which it sometimes very manifestly exhibits; alto- gether without taste, and impalpable; not condensable by any degree of cold into the dense fluid state, though easily changing its dimensions with its temperature ; that it gra- vitates and is highly elastic ; are among the numerous observations and discoveries which do honour to the sagacity of the philosophers of the seventeenth century. They likewise knew that this fluid is indispensably necessary to combustion ; but no one, except the great, though neglected, John Mayow, appears to have formed any proper notion of its manner of acting in that process. The air of the atmosphere, like other fluids, appears to be capable of holding bodies in solution. It takes up water in considerable quantities, with a dimunition of its own spe- cific gravity; from which circumstance, as well as from the consideration that water rises very plentifully in the vaporous state in vacua, it seems probable, that the air sus- pends vapour, not so much by a real solution., AIR 113 AIR as by keeping its particles asunder, and pre- venting their condensation. Water likewise dissolves or absorbs air. Mere heating or cooling does not affect the chemical properties of atmospherical air j but actual combustion, or any process of the same nature, combines its oxygen, and leaves its nitrogen separate. Whenever a process of this kind is carried on in a vessel containing at- mospherical air, which is enclosed either by inverting the vessel over mercury, or by stop- ping its aperture in a proper manner, it is found that the process ceases after a certain time ; and that the remaining air (if a com- bustible body capable of solidifying the oxygen, such as phosphorus, have been employed), has lost about a fifth part of its volume, and is of such a nature as to be incapable of main- taining any combustion for a second time, or of supporting the life of animals. From these experiments it is clear, that one of the follow- ing deductions must be true : 1. The com- bustible body has emitted some principle, which, by combining with the air, has ren- dered it unfit for the purpose of further com- bustion ; or, 2. It has absorbed part of the air which was fit for that purpose, and has left a residue of a different nature ; or, 3. Both events have happened ; namely, that the pure part of the air has been absorbed, and a prin- ciple has been emitted, which has changed the original properties of the remainder. The facts must clear up these theories. The first induction cannot be true, because the re- sidual ah- is not only of less bulk, but of less specific gravity, than before. The air cannot therefore have received so much as it has lost. The second is the doctrine of the philosophers who deny the existence of phlogiston, or a principle of inflammability ; and the third must be adopted by those who maintain that such a principle escapes from bodies during combustion. This residue was called phlo- gisticated air, in consequence of such an opinion. In the opinion that inflammable air is the phlogiston, it is not necessary to reject the second inference, that the air has been no otherwise changed than by the mere subtrac- tion of one of its principles : for the pure or vital part of the air may unite with inflam- mable air supposed to exist in a fixed state in the combustible body ; and if the product of this union still continues fixed, it is evident, that the residue of the air, after combustion, will be the same as it would have been if the vital part had been absorbed by any other fixed body. Or, if the vital air be absorbed, while inflammable air or phlogiston is dis- engaged, and unites with the aeriform residue, this residue will not be heavier than before, unless the inflammable air it has gained ex- ceeds in weight the vital air it has lost ; and if the inflammable air falls short of that weight, the residue will be lighter. These theories it was necessary to mention ; but it has been sufficiently proved by various experiments, that combustible bodies take oxygen from the atmosphere, and leave nitro- gen.; and that when these two fluids are again mixed in due proportions, they compose a mixture not differing from atmospherical air. The respiration of animals produces the same effect on atmospherical air as combustion does, and their constant heat appears to be an effect of the same nature. When an animal is included in a limited quantity of atmospherical air, it dies as soon as the oxygen is consumed ; and no other air will maintain animal life but oxygen, or a mixture which tontains it. Pure oxygen maintains the life of animals much longer than atmospherical air, bulk for bulk. It is to be particularly observed, however, that, in many cases of combustion, the oxygen of the air, in combining with the combustible body, produces a compound, not solid or liquid, but aeriform. The residual air will therefore be a mixture of the nitrogen of the atmosphere with the consumed oxygen, con- verted into another gas. Thus, in burning charcoal, the carbonic acid gas generated, mixes with the residual nitrogen, and makes up exactly, when the effect of heat ceases, the bulk of the original air. The breathing of animals, in like manner, changes the oxygen into carbonic acid gas, without altering the atmospherical volume. There are many provisions in nature by which the proportion of oxygen in the atmo- sphere, which is continually consumed in respiration and combustion, is again restored to that fluid. In fact there appears, as far as an estimate can be formed of the great and general operations of nature, to be at least as gieat an emission of oxygen, as is sufficient to keep the general mass of the atmosphere at the same degree of purity. Thus in volcanic erup- tions there seems to be at kast as much oxygen emitted or extricated by fire from various mi- nerals, as is sufficient to maintain the com- bustion, and perhaps even to meliorate the atmosphere. And in the bodies of plants and animals, which appear in a great measure to derive their sustenance and augmentation from the atmosphere and its contents, it is found that a large proportion of nitrogen exists. Most plants emit oxygen in the sunshine, from which it is highly probable that they imbibe and decompose the air of the atmosphere, re- taining carbon, and emitting the vital part. Lastly, if to this we add the decomposition of water, there will be numerous occasions in which this fluid will supply us with disengaged oxygen; while, by a very rational suppo- sition, its hydrogen may be considered as having entered into the bodies of plants, for the formation of oils, sugars, mucilages, && from which it may be again extricated. To determine the respirability or purity of air, it is evident that recourse must be had to AIR 114 AIR its comparative efficacy in maintaining com- bustion, or some other equivalent process. This subject will be considered under the article EUDIOMETER. From the latest and most accurate expe- riments, the proportion of oxygen in atmo- spheric air is by measure about 21 per cent. ; and it appears to be very nearly the sama whether it be in this country or on the coast of Guinea, on low plains or lofty mountains, or even at the height of 7250 yards above the level of the sea, as ascertained by Gay Lussac in his aerial voyage in September 1 805. The remainder of the air is nitrogen, with a small portion of aqueous vapour, amounting to about 1 per cent, in the driest weather, and a still less portion of carbonic acid, not exceeding a thousandth part of the whole. As oxygen and nitrogen differ in specific gravity in the proportion of 135 to 121, ac- cording to Kirwan, and of 13!) to 120 accord- ing to Davy, it has been presumed, that the oxygen would be more abundant in the lower regions, and the nitrogen in the higher, if they constituted a mere mechanical mixture, which appears contrary to the fact. On the other hand, it has been urged, that they cannot be in the state of chemical combination, because they both retain their distinct properties un- altered, and no change of temperature or density takes place on their union. But per- haps it may be said, that, as they have no repugnance to mix with each other, as oil and water have, the continual agitation to which the atmosphere is exposed, may be sufficient to prevent two fluids, differing not more than oxygen and nitrogen in gravity, from separ- ating by subsidence, though simply mixed. On the contrary, it may be argued, that to say chemical combination cannot take place without producing new properties, which did riot exist before in the component parts, is merely beg- ging the question ; for though this generally appears to be the case, and often in a very striking manner, yet combination does not always produce a change of properties, as ap- pears in M. Biot's experiments with various substances, of which we may instance water, the refraction of which is precisely the mean of that of the oxygen and hydrogen, which are indisputably combined in it. To get rid of the difficulty, Mr. Dalton of Manchester framed an ingenious hypothesis, that the particles of different gases neither attract nor repel each other ; so that one gas expands by the repulsion of its own particles, without any more interruption from the pre- sence of another gas, than if it were in a vacuum. This would account for the state of atmospheric air, it is true ; but it does not agree with certain facts. In the case of the carbonic acid gas in the Grotto del Cano, and over the surface of brewers' vats, why does not this gas expand itself freely upward, if the superincumbent gases do not press upon it ? Mr. Dalton himself, too, instances as an argu- ment for his hypothesis, that oxygen and hydrogen gases, when mixed by agitation, do not separate on standing. But why should either oxygen or hydrogen require agitation, to diffuse it through a vacuum, in which, ac- cording to Mr. Dalton, it is placed ? The theory of Berthollet appears consistent with all the facts, and sufficient to account for the phenomenon. If two bodies be capable of chemical combination, their particles must have a mutual attraction for each other. This attraction, however, may be so opposed by concomitant circumstances, that it may be diminished in any degree. Thus we know, that the affinity of aggregation may occasion a body to combine slowly with a substance for which it has a powerful affinity, or even entirely prevent its combining with it; the presence of a third substance may equally prevent the combination ; and so may the absence of a certain quantity of caloric. But in all these cases the attraction of the particles must subsist, though diminished or coun- teracted by opposing circumstances. Now we know that oxygen and nitrogen are capable of combination ; their particles, therefore, must attract each other ; but in the circumstances in which they are placed in our atmosphere, that attraction is prevented from exerting it- self to such a degree as to form them into a chemical compound, though it operates with sufficient force to prevent their separating by their difference of specific gravity. Thus the state of the atmosphere is accounted for, and every difficulty obviated, without any new hypothesis. The exact specific gravity of atmospherical air, compared to that of water, is a very nice and important problem. By reducing to 60 Fahr. and to 30 inches of the barometer, the results obtained with great care by MM. Biot and Arago, the specific gravity of atmo- spherical air appears to be 0.001220, water being represented by 1.000000. This relation expressed fractionally is ^i^-, or water is 820 times denser than atmospherical air. Mr. Rice, in the 77th and 78th numbers of the Annals of Philosophy, deduces from Sir George Shuckburgh's experiments 0.00120855 for the specific gravity of air. This number gives water to air as 827.437 to 1. If with Mr. Rice we take the cubic inch of water = 252.525 gr. then 100 cubic inches of air by Biot's experiments will weigh 30.808 grains, and by Mr. Rice's estimate 30.519. He con- siders with Dr. Prout the asmosphere to be a compound of 4 volumes of nitrogen, and 1 of oxygen ; the specific gravity of the first being to that of the second as 1.1111 to 0.9722. Hence 0.8 vol. nitr. sp. gr. 0.001166=0.000933 0.2 oxy. 0.001340 = 0.000268 0.001201 ALA 115 ALB The numbers are transposed in the Annals of Philosophy by some mistake. MM. Biot and Arago found the specific gravity of oxygen to be . v 1.10359 and that of nitrogen, , . . 0.96913 air being reckoned, . . . 1.00000 Or compared to water as unity, Nitrogen is 0.001182338 Oxygen, 0.001346379 And 0.8 nitrogen =0.00094587 0.2 oxygen =0.00026927 0.00121514 And 0.79 nitrogen =0.000934 0.21 oxygen =0.000283 0.001217 A number which approaches very nearly to the result of experiment. Many analogies, it must be confessed, favour Dr. Prout's pro- portions ; but the greater number of experi- ments OH the composition and density of the atmosphere agree with Biot's results. Nothing can decide these fundamental chemical pro- portions except a new, elaborate, and most minutely accurate series of experiments. We shall then know whether the atmosphere con- tains in volume 20 or 21 per cent, of oxygen. See METEOROLOGY and GAS. ALALITE. SeeDiopsiDE. ALABASTER. Among the stones which are known by the name of marble, and have been distinguished by a considerable variety of denominations by statuaries and others, whose attention is more directed to their ex- ternal character and appearance than their component parts, alabasters are those which have a greater or less degree of imperfect transparency, a granular texture, are softer, take a duller polish than marble, and are usually of a whiter colour. Some stones, how- ever, of a veined and coloured appearance, have been considered as alabasters, from their possessing the first mentioned criterion ; and some transparent and yellow sparry stones have also received this appellation. Chemists are at present agreed in applying this name only to such opaque, consistent, and semitransparent stones, as are composed of lime united with the sulphuric acid. But the term is much more frequent among masons and statuaries than chemists. Chemists in general confound the alabasters among the selenites, gypsums, or plaster of Paris, more especially when they allude only to the com- ponent parts, without having occasion to con- sider the external appearance, in which only these several compounds differ from each other. As the semi-opaque appearance and gra- nular texture arise merely from a disturbed or successive crystallization, which would else have formed transparent spars, it is accord- ingly found, that the calcareous stalactites, or drop-stones, formed by the transition of water through the roofs of caverns in a calcareous soil, do not differ in appearance from the alabaster, most of which is also formed in this manner. But the calcareous stalactites here spoken of consist of calcareous earth and car- bonic acid ; while the alabaster of the chemists is formed of the same earth and sulphuric acid, as has already been remarked. ALBIN. A mineral discovered at Mo- naberg, near Aussig, in Bohemia ; and being of an opaque white colour, has been called, by Werner, Albln. Aggregated crystalline laminae constitute massive albin. Small crystals of it in right prisms, whose summits consist of four quadrangular planes, are found sprinkled over mammelated masses in cavities. See ZEOLITE. ALBITE. A mineral in crystals, fre- quently, or, almost always, met under the form of hemitropes. These hemitropes are formed when two crystals are so joined to each other, that the upper plane of the one is ap- plied upon the inferior plane of the other. See CLEAVELANDITE, which is the name now given to this mineral. ALBUM GRJGCUM. Innumerable are the instances of fanciful speculation and absurd credulity in the invention and application of subjects in the more ancient materia medica. The white and solid excrement of dogs, which subsist chiefly on bones, was received as a remedy in the medical art, under the name of Album Graecum. It consists, for the most part, of the earth of bones or lime, in com- bination with phosphoric acid. ALBUMEN. This substance, which de- rives its name from the Latin for the white of an egg, in which it exists abundantly, and in its purest natural state, is one of the chief constituent principles of all the animal solids. Beside the white of egg, it abounds in the serum of blood, the vitreous and crystalline humours of the eye, and the fluid of dropsy. Fourcroy claims to himself the honour of hav- ing discovered it in the green feculae of plants in general, particularly in those of the cruciform order, in very young ones, and in the fresh shoots of trees, though Rouelle appears to have detected it there long before. Vau- quelin says it exists also in the mineral water of Plombieres. M. Seguin has found it in remarkable quan- tity in such vegetables as ferment without yeast, and afford a vinous liquor ; and from a series of experiments he infers, that albumen is the true principle of fermentation, and that its action is more powerful in proportion to its solubility, three different degrees of which he found it to possess. The chief characteristic of albumen is its coagulability by the action of heat. If the white of an egg be exposed to a heat of about 134 F. white fibres begin to appear in, it, and at 160 it coagulates into a solid mass. In a heat not exceeding 212 it dries, shrinks, and i 2 ALB 116 A'LC assumes the appearance of horn. It is soluble in cold water before it has been coagulated, but not after ; and when diluted with a very large portion, it does not coagulate easily. Pure alkalis dissolve it, even after coagulation. It is precipitated by muriate of mercury, nitro- rmuiate of tin, acetate of lead, nitrate of silver, muriate of gold, infusion of galls, and tannin. The acids and metallic oxides coagulate albu- men. On the addition of concentrated sul- phuric acid, it becomes black, and exhales a nauseous smell. Strong muriatic acid gives a violet tinge to the coagulum, and at length becomes saturated with ammonia. Nitric acid, at 70 F. disengages from it abundance of azotic gas ; and if the heat be increased, prussic acid is formed, after which carbonic acid and carburetted hydrogen are evolved, and the residue consists of water containing a little oxalic acid, and covered with a lemon- coloured fat oil. If dry potash or soda be triturated with albumen, either liquid or solid, ammoniacal gas is evolved, and the calcination of the residuum yields an alkaline prussiate. On exposure to the atmosphere in a moist state, albumen passes at once to the state of putrefaction. Solid albumen may be obtained by agitat- ing white of egg with ten or twelve times its weight of alcohol. This seizes the water which held the albumen in solution ; and this sub- stance is precipitated under the form of white flocks or filaments, which cohesive attraction renders insoluble, and which consequently may be freely washed with water. Albumen thus obtained is like fibrine, solid, white, insipid, inodorous, denser than water, and without action on vegetable colours. It dissolves in potash and soda more easily than fibrine ; but in acetic acid and ammonia with more diffi- culty. When these two animal principles are separately dissolved in potash, muriatic acid added to the albuminous does not disturb the solution, but it produces a cloud in the other. Fourcroy and several other chemists have ascribed the characteristic coagulation of al- bumen by heat to its oxygenation. But co- hesive attraction is the real cause of the phe- nomenon. In proportion as the temperature rises, the particles of water and albumen recede from each other, their affinity diminishes, and then the albumen precipitates. However, by uniting albumen with a large quantity of water, we diminish its coagulating property to such a degree, that heat renders the solution merely opalescent. A new-laid egg yields a soft coagulum by boiling ; but when, by keep- ing, a portion of the water has transuded so as to leave a void space within the shell, the con- centrated albumen affords a firm coagulum. An analogous phenomenon is exhibited by ace- tate of alumina, a solution of which, being heated, gives a precipitate in flakes, which re- dissolve as the caloric which separated the particles of acid and base escapes, or as the temperature falls. A solution containing ^ of dry albumen forms by heat a solid coa- gulum ; but when it contains only J-^, it gives a glairy liquid. One thousandth part, how- ever, on applying heat, occasions opalescence. Putrid white of egg, and the pus of ulcers, have a similar smell. According to Dr. Bos- tock, a drop of a saturated solution of cor- rosive sublimate let fall into water containing 5^Vo f albumen, occasions a milkiness and curdy precipitate. On adding a slight excess of the mercurial solution to the albuminous liquid, and applying heat, the precipitate which falls, being dried, contains in every 7 parts, 5 of albumen. Hence that salt is the most de- licate test of this animal product. The yellow pitchy precipitate occasioned by tannin is brit- tle when dried, and not liable to putrefaction. But tannin, or infusion of galls, is a much nicer test of gelatin than of albumen. The cohesive attraction of coagulated al- bumen makes it resist putrefaction. In this state it may be kept for weeks under water without suffering change. By long digestion in weak nitric acid, albumen seems convertible into gelatin. By the analysis of Gay Lussac and Thenard, 1 00 parts of albumen are formed of 52.883 carbon, 23.872 oxygen, 7.540 hy- drogen, 15.705 nitrogen ; or in other terms, of 52.883 carbon, 27-127 oxygen and hydro- gen, in the proportions for constituting water, 15.705 nitrogen, and 4.285 hydrogen in ex- cess. The negative pole of a voltaic pile in high activity coagulates albumen ; but if the pile be feeble, coagulation goes on only at the positive surface. Albumen, in such a state of concentration as it exists in serum of blood, can dissolve some metallic oxides, particularly the protoxide of iron. Orfila has found white of egg to be the best antidote to the poisonous effects of corrosive sublimate on the human stomach. As albumen occasions precipitates with the solutions of almost every metallic salt, probably it may act beneficially against other species of mineral poison. From its coagulability albumen is of great use in clarifying liquids. See CLARIFICA- TION. It is likewise remarkable for the property of rendering leather supple, for which purpose a solution of whites of eggs in water is used by leather-dressers; and hence Dr. Lobb, of Yeovil, in Somersetshire, was induced to em- ploy this solution in cases of contraction and rigidity of the tendons, and derived from it apparent success. Whites of eggs beaten in a basin with a lump of alum, till they coagulate, form the alum curd of Riverius, or alum cataplasm of the London Pharmacopoeia, used to remove inflammations of the eyes. ALBURNUM. The interior white bark of trees. ALCARRAZAS. A species of porous, pottery made in Spain, for the purpose of ALC 117 ALC cooling water by its transudation and copious evaporation from the sides of the vessel. M. l)arcet gives the following as the analysis of the clay which is employed for the purpose : ()0 calcareous earth, mixed with alumina and a little peroxide of iron, and 36 of siliceous earth, mixed with a little alumina. In work- ing up the earths with water, a quantity of salt is added, and dried in it. The pieces are only half baked. ALCHEMY. A title of dignity, given in the dark ages, by the adepts, to the mystical art by which they professed to find the philo- sopher's stone, that was to transmute base metals into gold, and prepare the elixir of life. Though avarice, fraud, and folly were their motives, yet their experimental researches were instrumental in promoting the progress of che- mical discovery. Hence, in particular, metallic pharmacy derived its origin. ALCOHOL. This term is applied in strictness only to the pure spirit obtainable by distillation and subsequent rectification from all liquids that have undergone vinous fer- mentation, and from none but such as are susceptible of it But it is commonly used to signify this spirit more or less ivnperfectly freed from water, in the state in which it is usually met with in the shops, and in which, as it was first obtained from the juice of the grape, it was long distinguished by the name of spirit of wine. At present it is extracted chiefly from grain or melasses in Europe, and from the juice of the sugar-cane in the West Indies; and in the diluted state in which it commonly occurs in trade, constitutes the basis of the several spirituous liquors called brandy, rum, gin, whisky, and cordials, however va- riously denominated or disguised. As we are not able to compound alcohol im- mediately from its ultimate constituents, we have recourse to the process of fermentation, by which its principles are first extricated from the substances in which they were combined, and then united into a new compound ; to dis- tillation, by which this new compound, the alcohol, is separated in a state of dilution with water, and contaminated with essential oil ; and to rectification, by which it is ultimately freed from these. It appears to be essential to the fermentation of alcohol, that the fermenting fluid should contain saccharine matter, which is indispens- able to that species of fermentation called vi- nous. In France, where a great deal of wine is made, particularly at the commencement of the vintage, that is too weak to be a saleable commodity, it is a common practice to subject this wine to distillation, in order to draw off the spirit ; and as the essential oil that rises in this process is of a more pleasant flavour than that of malt or melasses, the French brandies are preferred to any other ; though even in the flavour of the^e there is a difference, according to the wine from which they are produced. In the West Indies a spirit is obtained from the juice of the sugar-cane, which is highly im- pregnated with its essential oil, and well known by the name of rum. The distillers in this country use grain, or melasses, whence they distinguish the products by the name of malt spirits and melasses spirits. It is said that a very good spirit may be extracted from the husks of gooseberries or currants, fifter wine has been made from them. As the process of malting developes the sac- charine principle of grain, it would appear to render it fitter for the purpose ; though it is the common practice to use about six parts of raw grain with one of malt. For this two reasons may be assigned : by using raw grain the expense of malting is saved, as well as the duty on malt ; and the process of malting re- quires some nicety of attention, since, if it be carried too far, part of the saccharine matter is lost, and if it be stopped too soon, this mat- ter will not be wholly developed. Besides, if the malt be dried too quickly, or by an un- equal heat, the spirit it yields will be less in quantity, and more unpleasant .in flavour. Another object of economical consideration is, what grain will afford the most spirit in pro- portion to its price, as well as the best in qua- lity. Barley appears to produce less spirit than wheat ; and if three parts of raw wheat be mixed with one of malted barley, the pro- duce is said to be particularly fine. This is the practice of the distillers in Holland for producing a spirit of the finest quality; but in England they are expressly prohibited from using more than one part of wheat to two of other grain. Rye, however, affords still more spirit than wheat. The practice with the distillers in Scotland is to use one part of malted with from four to nine parts of unmalted grain. This mixture yields an equal quantity of spirit, and at a much cheaper rate than when the former pro- portions are taken. Whatever be the grain employed, it must be coarsely ground, and then mixed carefully with a little cold water, to prevent its run- ning into lumps; water about 140 F. may then be added, till it is sufficiently mashed ; and to the drained off wort, yeast is added. The wort is then to be allowed to ferment in a covered vessel, to which, however, the air can have access. Attention must be paid to the temperature : for if it exceed 87 F. the fermentation will be too rapid ; if it be below 60, the fermentation will cease. The mean between these will generally be found most favourable. In this country it is the more common practice to mash the grain as for brewing malt liquors, and boil the wort. But in whichever way it be prepared, or if the wash (so the liquor intended for distillation is called) be made from melasses and water, due atten- tion must be paid to the fermentation, that it be continued till the liquor grows fin:;, and ALC 118 ALC ^pungent to the taste, which will generally be about the third day, but not so long as to per- mit the acetous fermentation to commence. In this state the wash is to be committed to the still, of which, including the head, it should occupy at least three-fourths ; and distilled with a gentle heat as long as any spirit comes over, which will be till about half the wash is con- sumed. The more slowly the distillation is conducted, the less will the product be con- taminated with essential oil, and the less dan- ger will there be of empyreuma. A great saving of time and fuel, however, may be obtained by making the still very broad and shallow, and contriving a free exit for the steam. This has been carried to such a pitch in Scotland, that a still measuring 43 gallons, and containing 16 gallons of wash, has been charged and worked no less than four hundred and eighty times in the space of twenty-four hours. This would be incredible, were it not established by unquestionable evidence. See LABORATORY, article STILL. The above wonderful rapidity of distillation has now ceased since the excise duties have been levied on the quantity of spirit produced, and not, as formerly, by the size of the still. Hence, too, the spirit is probably improved in flavour. The first product, technically termed low wine, is again to be subjected to distillation, the latter portions of what comes over, called feints, being set apart to be put into the wash- still at some future operation. Thus a large portion of the watery part is left behind. This second product, termed raw spirit, being dis- tilled again, is called rectified spirit. It is calculated, that a hundred gallons of malt or corn wash will not produce above twenty of spirit, containing 60 parts of alcohol to 50 of water : the same of cyder wash, 1 5 gallons ; and of melasses wash, 22 gallons. The most r* ituous wines of France, those of Langue- , Guienne, and Rousillon, yield, according to Chaptal, from 20 to 25 gallons of excellent brandy from J 00 ; but those of Burgundy and Champagne much less. Brisk wines contain- ing much carbonic acid, from the fermentation having been stopped at an early period, yield the least spirit. The spirit thus obtained ought to be colour- less, and free from any disagreeable flavour ; and in this state it is fittest for pharmaceutical purposes, or the extraction of tinctures. But for ordinary sale something more is required. The brandy of France, which is most in esteem here, though perfectly colourless when first made, and often preserved so for use in that country, by being kept in glass or stone bottles, is put into new oak casks for exportation, whence it soon acquires an amber colour, a peculiar flavour, and something like an unc- tuosity of consistence. As it is not only prized for these qualities, but they are commonly deemed essential to it, the English distiller imitates by design these accidental qualities. The most obvious and natural method of doing this would be by impregnating a pure spirit with the extractive, resinous, and colouring matter of oak shavings ; but other modes have been contrived. The dulcified spirit of nitre, as it is called, is commonly used to give the flavour ; and catechu, or burnt sugar, to im- part the desired colour. A French writer has recommended three ounces and a half of finely powdered charcoal, and four ounces and a half of ground rice, to be digested for a fortnight in a quart of malt spirit. The finest gin is said to be made in Holland, from a spirit drawn from wheat mixed with a third or fourth part of malted barley, and twice rectified over juniper berries ; but in general rye meal is used instead of wheat. They pay so much regard to the water employed, that many send vessels to fetch it on purpose from the Meuse ; but all use the softest and clearest river water they can get In England it is the common practice to add oil of turpentine, in the proportion of two ounces to ten gallons of raw spirit, with three handfuls of bay salt, and drawn off till the feints begin to rise. But corn or melasses spirit is flavoured like- wise by a variety of aromatics, with or without sugar, to please different palates ; all of which are included under the general technical term of compounds or cordials. Other articles have been employed, though not generally, for the fabrication of spirit, as carrots and potatos; and we are lately in- formed by Professor Proust, that from the fruit of the carob tree he has obtained good brandy in the proportion of a pint from five pounds of the dried fruit. To obtain pure alcohol, different processes have been recommended ; but the purest rec- tified spirit obtained as above described, being that which is least contaminated with foreign matter, should be employed. Rouelle recom- mends to draw off half the spirit in a water bath ; to rectify this twice more, drawing off two-thirds each time; to add water to this alcohol, which will turn it milky by separating the essential oil remaining in it ; to distil the spirit from this water ; and finally rectify it by one more distillation. Baume sets apart the first running, when about a fourth is come over, and continues the distillation till he has drawn off about as much more, or till the liquor runs off milky. The last running he puts into the still again, and mixes the first half of what comes over with the preceding first product. This process is again repeated, and all the first products being mixed together, are distilled afresh. When about half the liquor is come over, this is to be set apart as pure alcohol. Alcohol in this state, however, is not so pure as when, to use the language of the old chemists, it has been dep, f ilegmated, or still further freed from water, by means of some alkaline salt. Boerhaave recommended, for this purpose, the muriate of soda, deprived of ALC 119 ALC its water of crystallization by heat, and added hot to the spirit But the subcarbonate of potash is preferable. About a third of the weight of the alcohol should be added to it in a glass vessel, well shaken, and then suffered to subside. The salt will be moistened by the water absorbed from the alcohol ; which being decanted, more of the salt is to be added, and this is to be continued till the salt falls dry to the bottom of the vessel. The alcohol in this state will be reddened by a portion of the pure potash, which it will hold in solution, from which it must be freed by distillation in a water bath. Dry muriate of lime may be sub- stituted advantageously for the alkali. By enclosing dilute alcohol in a bladder, the water exudes, and the spirit is concentrated. Soemmering says, that if we put alcohol of a moderate strength into an ox's bladder, or a calf's, coated . with isinglass, and suspend it over a sand bath, in a few days the alcohol will lose one-fourth of its bulk, and be found quite free from water, or become absolute al- cohol. Gior. di Fisica, vii. 239. As alcohol is much lighter than water, its specific gravity is adopted as the test of its purity. Fourcroy considers it as rectified to the highest point when its specific gravity is 829, that of water being 1000 ; and perhaps this is nearly as far as it can be carriecl by the process of Rouelle or Baume simply. M. Bories found the first measure that came over from twenty of spirit at 83G to be 820, at the tem- perature of 71 F. Sir Charles Blagden, by the addition of alkali, brought it to 813, at 60 F. Chaussier professes to have reduced it to 798 ; but he gives 998.35 as the specific gravity of water. Lowitz asserts that he has obtained it at 791, by adding as much alkali as nearly to absorb the spirit ; but the temperature is not indicated. In the shops it is about 835 or 840 : according to the London College it should be 815. It is by no means an easy undertaking to de- termine the strength or relative value of spirits, even with sufficient accuracy for commercial purposes. The following requisites must be obtained before this can be well done : the spe- cific gravity of a certain number of mixtures of alcohol and water must be taken so near each other, as that the intermediate specific gravities may not perceptibly differ from those deduced from the supposition of a mere mix- ture of the fluids ; the expansions or variations of specific gravity in these mixtures must be determined at different temperatures ; some easy method must be contrived of determining the presence and quantity of saccharine or ole- aginous matter which the spirit may hold in solution, and the effect of such solution on the specific gravity ; and lastly, the specific gra- vity of the fluid must be ascertained by a pro- per floating instrument with a graduated stem, or set of weights ; or, which may be more con- venient, with both. The strength of brandies in commerce is judged by the phial, or by burning. The phial proof consists In agitating the spirit in a bottle, and observing the form and magnitude of the bubbles that collect round the edge of the li- quor, technically termed the bead, which are larger the stronger the spirit. These probably depend on the solution of resinous matter from the cask, which is taken up in greater quan- tities, the stronger the spirit. It is not diffi- cult, however, to produce this appearance by various simple additions to weak spirit. The proof by burning is also fallacious ; because the magnitude of the flame, and quantity of residue, in the same spirit, vary greatly with the form of the vessel it is burned'in. If the vessel be kept cool, or suffered to become hot, if it be deeper or shallower, the results will not be the same in each case. It does not follow, however, but that manufacturers and others, may in many instances receive considerable in- formation from these signs, in circumstances exactly alike, and in the course of operations wherein it would be inconvenient to recur con- tinually to experiments of specific gravity. The importance of this object, as well for the purposes of revenue as of commerce, in- duced the British government to employ Dr. Blagden, now Sir Charles, to institute a very minute and accurate series of experiments. These may be considered as fundamental re- sults; for which reason, I shall give a sum- mary of them in this place, from the Philo- sophical Transactions for 1790. The first object to which the experiments were directed, was to ascertain the quantity and law resulting from the mutual penetration of water and spirit. All bodies in general expand by heat ; but the quantity of this expansion, as well as the law of its progression, is probably not the same in any two substances. In water and spirit they are remarkably different. The whole expansion of pure spirit from 30 to 100 of Fahrenheit's thermometer is not less than l-25th of its whole bulk at 30; where- as that of water, in the same interval, is only 1-145 of its bulk. The laws of their expan- v sion are still more different than the quantities. If the expansion of quicksilver be, as usual, taken for the standard, (our thermometers be- ing constructed with that fluid), the expansion of spirit is, indeed, progressively increasing with respect to that standard, but not much so within the abovementioned interval ; while water kept from freezing to 30, which may easily be done, will absolutely contract as it is heated for ten or more degrees, that is to 40 or 42 of the thermometer, and will then begin to expand as its heat is augmented, at first slowly, and afterward gradually more rapidly, so as to observe upon the whole a very in- creasing progression. Now, mixtures of these two substances will, as may be supposed, ap- proach to the less or the greater of these pro- gressions, according as they are compounded of more spirit or more water, while their total ALC 120 ALC expansion will be greater, according as more spirit enters into their composition ; but the exact quantity of the expansion, as well as law of the progression, in all of them, can be de- termined only by trials. These were, there- fore, the two other principal objects to be as- certained by experiment. The person engaged to make these experi- ments was Dr. Dollfuss, an ingenious Swiss gentleman then in London, who had distin- guished himself by several publications on chemical subjects. As he could not conve- niently get the quantity of spirit he wanted lighter than 825, at 60 F., he fixed upon this strength as the standard for alcohol. These experiments of Dr. Dollfuss were re- peated by Mr. Gilpin, clerk of the Royal So- ciety ; and as the deductions in this account will be taken chiefly from that last set of ex- periments, it is proper here to describe mi- nutely the method observed by Mr. Gilpin in his operation. This naturally resolves itself into two parts : the way of making the mix- tures, and the way of ascertaining their specific gravity. 1. The mixtures are made by weight, as the only accurate method of fixing the proportions- In fluids of such very unequal expansions by heat as water and alcohol, if measures had been employed, increasing or decreasing in re- gular propoitions to each other, the proportions of the masses would have been sensibly irre- gular: now the v latter was the object in view, namely, to determine the real quantity of spirit in any given mixture, abstracting the consi- deration of its temperature. Besides, if the proportions had been taken by measure, a dif- ferent mixture should have been made at every different degree of heat. But the principal con- sideration was, that with a very nice balance, such as was employed on this occasion, quan- tities can be determined to much greater ex- actness by weight than by any practicable way of measurement. The proportions were there- fore always taken by weight. A phial being provided of such a size as that it should be nearly full with the mixture, was made per- fectly clean and dry, and being counterpoised, as much of the pure spirit as appeared neces- sary was poured into it. The weight of this spirit was then ascertained, and the weight of distilled water required to make a mixture of the intended proportions was calculated. This quantity of water was then added, with all the necessary care, the last portions being put in by means of a well-known instrument, which is composed of a small dish terminating in a tube drawn to a fine point : the top of the dish being covered with the thumb, the liquor in it is prevented from running out through the tube by the pressure of the atmosphere, but in- stantly begins to issue by drops, or a very small stream, upon raising the thumb. Water be- ing thus introduced into the phial, till it ex- actly counterpoised the weight, which having been previously computed, was put into the opposite scale, the phial was shaken, and then well stopped with its glass stopple, over which leather was tied very tight to prevent evapora- tion. No mixture was used till it had re- mained in the phial at least a month, for the full penetration to have taken place ; and it was always well shaken before it was poured out to have its specific gravity tried. 2. There are two common methods of taking the specific gravity of fluids ; one by finding the weight which a solid body loses by being immersed in them ; the other, by filling a con- venient vessel with them, and ascertaining the increase of weight it acquires. In both cases a standard must have been previously taken, which is usually distilled water ; namely, in the first method, by finding the weight lost by the solid body in the water ; and in the second method, the weight of the vessel filled with water. The latter was preferred, for the fol- lowing reasons: When a ball of glass, which is the properest kind of solid body, is weighed in any spiritu- ous or watery fluid, the adhesion of the fluid occasions some inaccuracy, and renders the balance comparatively sluggish. To what degree this effect proceeds is uncertain ; but from some experiments made by Mr. Gilpin with that view, it appears to be very sensible. Moreover, in this method a large surface must be exposed to the air during the operation of weighing, which, especially in the higher tem- peratures, would give occasion to such an evaporation as to alter essentially the strength of the mixture. It seemed also as if the tem- perature of the fluid under trial could be de- termined more exactly in the method of filling a vessel, than in the other: for the fluid cannot well be stirred while the ball to be weighed remains immersed in it ; and as some time must necessarily be spent in the weigh- ing, the change of heat which takes place during that period will be unequal through the mass, and may occasion a sensible error. It is true, on the other hand, that in the method of filling a vessel, the temperature could not be ascertained with the utmost pre- cision, because the neck of the vessel employed, containing about ten grains, was filled up to the mark with spirit not exactly of the same temperature, as will be explained presently: but this error, it is supposed, would by no means equal the other, and the utmost quan- tity of it may be estimated very nearly. Finally, it was much easier to bring the fluid to any given temperature when it was in a vessel to be weighed, than when it was to have a solid body weighed in it; because in the former case the quantity was smaller, and the vessel containing it more manageable, being readily heated with the hand or warm water, and cooled with cold water: and the very circumstance, that so much of the fluid was not required, proved a material conve- nience. The particular disadvantage in the method of weighing in a vessel, is the diffi- ALC 121 ALC CAilty of filling it with extreme accuracy ; but when the vessel is judiciously and neatly marked, the error of filling will, with due care, be exceedingly minute- By several repeti- tions of the same experiments, Mr. Gilpin seemed to bring it within the l-15000th part of the whole weight. The above-mentioned considerations in- duced Dr. Blagden, as well as the gentlemen employed in the experiments, to give the preference to weighing the fluid itself; and that was accordingly the method practised both by Dr. Dollfuss and Mr. Gilpin in their operations. The vessel chosen as most convenient for the purpose was a hollow glass ball, termi- nating in a neck of small bore. That which Dr. Dollfuss used held 5800 grains of dis- tilled water; but as the balance was so ex- tremely accurate, it was thought expedient, upon Mr. Gilpin's repetition of the experi- ments, to use one of only 2965 grains capacity, as admitting the heat of any fluid contained in it to be more nicely determined. The ball of this vessel, which may be called the weighing bottle, measured about 2.8 inches in diameter, and was spherical, except a slight flattening on the part opposite to the neck, which served as a bottom for it to stand upon. Its neck was formed of a portion of a barometer tube, .25 of an inch in bore, and about 1^ inch long; it was perfectly cylindrical, and, on its out- side, very near the middle of its length, a fine circle or ring was cut round it with a diamond, as the mark to which it was to be filled with the liquor. This mark was made by fixing the bottle in a lathe, and turning it round with great care, in contact with the diamond. The glass of this bottle was not very thick ; it weighed 91 G grains, and with its silver cap 936. When the specific gravity of any liquor was to be taken by means of this bottle, the liquor was first brought nearly to the required tem- perature, and the bottle was filled with it up to the beginning of the neck only, that there might be room for shaking it. A very fine and sensible thermometer was then passed through the neck of the bottle into the con- tained liquor, which showed whether it was above or below the intended temperature. In the former case the bottle was brought into colder air, or even plunged for a moment into cold water; the thermometer in the mean time being frequently put into the contained liquor, till it was found to sink to the right point In like manner, when the liquor was too cold, the bottle was brought into warmer air, im- mersed in warm water, or more commonly held between the hands, till upon repeated trials with the thermometer the just tempe- rature was found. It will be understood, that during the course of this heating or cooling, the bottle was very frequently shaken between each immersion of the thermometer ; and the top of the neck was kept covered, cither with the finger, or a silver cap made on purpose, as constantly as possible. Hot water was used to raise the temperature only in heats of 80 and upwards, inferior heats being obtained by applying the hands to the bottle: when the hot water was employed, the ball of the bottle was plunged into it, and again quickly lifted out, with the necessary shaking inter- posed, as often as was necessary for commu- nicating the required heat to the liquor ; but care was taken to wipe the bottle dry after each immersion, before it was shaken, lest any adhering moisture might by accident get into it. The liquor having by these means been brought to the desired temperature, the next operation was to fill up the bottle exactly to the mark upon the neck, which was done with some of the same liquor, by means of a glass funnel with a very small bore. Mr. Gilpin endeavoured to get that portion of the liquor which was employed for this purpose, pretty nearly to the temperature of the liquor con- tained in the bottle ; but as the whole quan- tity to be added never exceeded ten grains, a difference of ten degrees in the heat of that small quantity, which is more than it ever amounted to, would have occasioned an error of only l-30th of a degree in the temperature of the mass. Enough of the liquor was put in to fill the neck rather above the mark, and the superfluous quantity was then absorbed to great nicety, by bringing into contact with it the fine point of a small roll of blotting paper. As the surface of the liquor in the neck would be always concave, the bottom or centre of this concavity was the part made to coincide with the mark round the glass ; and in viewing it, care was taken that the near and opposite sides of the mark should appear exactly in the same line, by which means all parallax was avoided. A silver cap, which fitted tight, was then put upon the neck to prevent evaporation ; and the whole apparatus was in that state laid in the scale of the balance, to be weighed with all the exactness possible. The spirit employed by Mr. Gilpin was furnished to him by Dr. Dollfuss, under whose inspection it had been rectified from rum sup- plied by government. Its specific gravity, at 60 degrees of heat, was .82514. It was first weighed pure, in the above-mentioned bottle, at every five degrees of heat from 30 to 100 inclusively. Then mixtures were formed of it and distilled water, in every proportion, from l-20th of the water to equal parts of water and spirit ; the quantity of water added being successively augmented, in the proportion of five grains to one hundred of the spirit ; and these mixtures were also weighed in the bottle, like the pure spirit, at every five degrees of heat. The numbers hence resulting are de- livered in the following table ; where the first column shows the degrees of heat ; the second gives the weight of the pure spirit contained in the bottle at those different degrees ; the third gives the weight of a mixture in the propor- ALC ALC tions of 100 parts by weight of that spirit to 5 of water, and so on successively till the water is to the spirit as 100 to 5. They are the mean of three several experiments at least, as Mr. Gilpin always filled and weighed the bottle over again that number of times, if not oftener. The heat was taken at the even degree, as shown by the thermometer, without any allowance in the first instance, because the coincidence of the mercury with a Division can be perceived more accurately than any fraction can be estimated ; and the errors of the ther- mometers, if any, it was supposed would be less upon the grand divisions of 5 degrees than in any others. It must be observed, that Mr. Gilpin used the same mixture throughout all the different temperatures, heating it up from 30 to 100; hence some small error in its strength may have been occasioned in the higher degrees, by more spirit evaporating than water : but this, it is believed, must have been trifling, and greater inconvenience would pro- bably have resulted from interposing a fresh mixture. The precise specific gravity of the pure spirit employed was .82514; but to avoid an inconvenient fraction, it is taken, in construct- ing the table of specific gravities, as .825 only, a proportional deduction being made from all the other numbers. Thus the following table gives the true specific gravity, at the different degrees of heat, of a pure rectified spirit, the specific gravity of which at CO is .825, to- gether with the specific gravities of different mixtures of it with water, at those different temperatures. Real Specific Gravities at the different Temperatures. Heat. The pure spirit. 100 Drains of spirit to 5 gr. of water. 100 grains of spirit to 10 gr. of water. 100 grains of spirit to 15 gr. of water. 100 grains of spirit to 20 gr. of water. 100 grains of spirit to 25 gr. Of water. 100 grains of spirit to 30 gr. of water. 100 grains of spirit to 35 gr. of water. 100 grains of spirit to 40 gr. of water. 100 grains of spirit to 45 gr. of water. 100 Drains of snirit to 00 gr. of water. 30 .83896 .84995 .85957 .86825 .87585 .88282 '.88921 .89511 .90054 .90558 91023 35 83672 84769 85729 86587 87357 88059 88701 89294 89839 90345 90811 40 83445 84539 85507 86361 i 87184 87838 88481 89073 89617 90127 90596 45 83214 84310 85277 86131 ! 86905 87613 1 88255 88849 89396 89909 90380 50 82977 84076 85042 85902 86676 87384 88030 88626 89174 89684 90160 55 82736 83834 84802 85664 86441 37150 87796 88393 88945 ; 89458 89933 60 82500 83599 84568 85430 86208 86918 87569 88169 88720 89232 89707 G5 82262 83362 84334 85193 85976 86686 87337 87938 88490 89006 89479 70 82023 83124 84092 84951 85736 86451 87105 87705 88254 88773 89252 75 81780 82878 ! 83851 84710 85496 86212 86864 87466 88018 ! 88538 89018 80 81530 82631 I 83603 84467 85248 85966 86622 87228 87776 88301 88781 85 81291 82396 83371 84243 85036 85757 86411 87021 87590 88120 88609 90 81044 82150 83126 84001 84797 85518 86172 86787 87360 87889 88376 95 80794 81900 82877 83753 84550 85272 85928 86542 87114 07654 80146 100 80548 81657 82639 83513 84038 85031 85688 86302 86879 87421 87915 Heat. 100 grains of spirit to 55 gr. of water. 100 Drains of spirit to 60 gr. of water. 100 Drains of spirit to 65 gr. Of water. 100 Drains of spirit to 70 gr. of water. 100 grains of spirit to 75 gr. of water. 100 grains of spirit to 80 gr. of water. 100 grains of spirit to 85 gr. of water. 100 grains of spirit to 90 gr. of water. 100 Drains of spirit to 95 gr. of water. 100 Drains of spirit to 100 gr.of water. 30 .91449 .91847 .92217 .92563 .92889 93191 .93474 .93741 .93991 .94222 35 91241 91640 92009 92355 92680 92986 93274 93541 93790 94025 40 91026 91428 91799 92151 92476 92783 93072 93341 93592 93827 45 90812 91211 91584 91937 92264 92570 92859 93131 93382 93621 50 90596 90997 91370 91723 92051 92358 92647 92919 93177 93419 55 90367 90768 91144 91502 91837 92145 92436 92707 92963 93208 60 90144 90549 90927 91287 91622 91933 92225 92499 92758 93002 65 89920 90328 90707 91066 91400 91715 92010 92283 92546 92794 70 89695 90104 90484 90847 91181 91493 91793 92069 92333 92580 75 89464 89872 90252 90617 90952 91270 91569 91849 92111 92364 80 89225 89639 90021 90385 90723 91046 91340 91622 91891 92142 85 89043 89460 89843 90209 90558 90882 91186 91465 91729 91969 90 88817 89230 89617 89988 90342 90668 90967 91248 91511 91751 95 88588 89003 89390 89763 90119 90443 90747 91029 91290 91531 100 88357 88769 89158 89536 89889 90215 90522 90805 91066 91310 ALC ALC 95 { 90 85 80 75 70 65 CO 55 50 Heat. grains of spirit to grains of spirit to grains of! grains of spirit to | spirit to grains of spirit to grains of spirit to grains of spirit to grains of spirit to grains of spirit to grains of spirit to lOOgr. of lOOgr.of lOOgr.of lOOgr.of lOOgr.of lOOgr.of lOOfcr.of lOOgr.of lOOgr.of lOOgr. of water. waier. water. water. water. water. water. water. water. water. 30 .94447 .04675 .94920 .95173 .95429 95681 .95944 .96209 .96470 .96719 35 94249 94484 94734 94988 95246 95502 95772 96048 96315 96579 40 94058 94295 94547 94802 95060 95328 95602 95879 96159 96434 45 93860 94096 94348 94605 94871 95143 95423 95705 95993 96280 50 93658 93897 94149 94414 94683 94958 95243 95534 95831 96126 55 93452 93696 93948 94213 94486 94767 95057 95357 95662 95966 60 93247 93493 93749 94018 94296 94579 94876 95181 95493 95804 65 93040 93285 93546 93822 94099 94388 94689 95000 95318 95635 70 92828 93076 93337 93616 93898 94193 94500 94813 95139 95469 75 92613 92865 93132 93413 93695 93989 94301 94623 94957 95292 80 92393 92646 92917 93201 93488 93785 94102 94431 94768 95111 45 40 35 30 25 20 15 10 5 grains of grains of grains of grains of grains of grains of grains of grains of grains of Heat. spirit to spirit to spirit to spirit to spirit to spirit to spirit to spirit to spirit to iOOgr. of 100 gr. of lOOgi.of lOOgr.of iOOgr.of loo gr. ot 100 gr. of lOOgr.of lOOgr.of water. water. water. water. water. water. water. water. water. 30 .96967 .97200 .97418 .97635 .97860 .98108 .98412 .98804 .99334 35 96840 97086 97319 97556 97801 98076 98397 98804 99344 40 96706 96967 97220 97472 97737 98033 98373 98795 99345 45 96563 96840 97110 97384 97666 97980 98338 98774 99338 50 96420 96708 96995 97284 97589 97920 98293 98745 99316 55 96272 96575 96877 97181 97500 97847 98239 98702 99284 60 96122 96437 96752 97074 97410 97771 98176 98654 99244 65 95962 96288 96620 96959 97309 97688 98106 98594 99194 70 95802 96143 96484 96836 97203 97596 98028 98527 99134 75 95638 95987 96344 98708 97086 97495 97943 98454 99066 80 95467 95826 96192 96568 96963 97385 97845 98367 98991 From this table, when the specific gravity of any spirituous liquor is ascertained, it will be easy to find the quantity of rectified spirit of the above-mentioned standard, contained in any given quantity of it, either by weight or measure. Dr. Blagden concludes this part of the re- port with observing, that as the experiments were made with pure spirit and water, if any extraneous substances are contained in the liquor to be tried, the specific gravity in the tables will not give exactly the proportions of water and spirit in it. The substances likely to be found in spirituous liquors, where no fraud is suspected, are essential oils, some- times empyreumatic, mucilaginous, or ex- tractive matter, and perhaps some saccharine matter. The effect of these, in the course of trade, seems to be hardly such as would be worth the cognizance of the excise, nor could it easily be reduced to certain rules. Essential and empyreumatic oils are nearly of the same specific gravity as spirit, in general rather lighter, and therefore, notwithstanding the mutual penetration, will probably make little change in the specific gravity of any spirituous liquor in which they are dissolved. The other substances are all heavier than spirit ; the spe- cific gravity of common gum being 1.482, and of sugar 1.606, according to the tables of M. Brisson. The effect of them therefore will be to make spirituous liquors appear less strong than they really are. An idea was once en- tertained of endeavouring to determine this matter with some precision ; and accordingly Dr. Dollfuss evaporated 1000 grains of brandy, and the same quantity of rum, to dryness ; the former left a residuum of 40 grains, the latter only of 8^ grains. The 40 grains of residuum from the brandy, dissolved again in a mixture of 100 of spirit, with 50 of water, increased its specific gravity .00041 ; hence the effect of this extraneous matter upon the specific gravity of the brandy containing it, would be to increase the fifth decimal by six nearly, equal to what would indicate in the above mentioned mix- ture about one -seventh of a grain of water more than the truth, to 100 of spirit ; a quan- tity much too minute for the consideration of government. The strength of spirits is determined, ac- cording to the existing laws, by Sikes's hydro- meter ; but as many dealers use Dicas's, I shall describe it here, and the former under DISTILLATION. It consists of a light copper ball, terminat- ing below with a ballast bottom, and above with a thin stem, divkled into ten parts. The ALC 124 ALC upper extremity of the stem is pointed, to re- ceive the little brass poises, or discs, having each a hole in its centre. These poises are numbered 0, 10, 20, 30, &c. up to 350, which is the lightest of the series. The intermediate units are given by the subdivisions on the stem. A graduated ivory scale, with a sliding rule and thermometer, accompanies the hydrometer, to make the correction for temperature. The first thing in using this instrument is to plunge the thermometer into a glass cylinder contain- ing the spirits to be tried. The sliding rule has then the degree of temperature indicated, moved opposite to zero. The hydrometer is now placed in the liquid, and such a poise is put on as to submerge a portion of the stem. The weight, added to the number on the stem, gives a sum, opposite to which on the scale we find a quantity by which the particular spirit may exceed or fall short of proof. Thus, if it mark 20 under proof, it signifies that every 100 gallons of that spirit would require to have 20 gallons of water abstracted from it to bring it up to proof. If it mark 10 over proof, we learn that every 100 gallons contain too little water by 10 gallons. When the ther- mometric degree of 60 is put opposite to zero, then the weights and value of the spirits have the following relations on the scale. 102.5 denotes 20 under proof 122,0 10 143.5 Proof 167. 10 over proof 193. denotes 20 over proof 221. 30 251. 40 284.5 50 322.5 60 350.5 Alcohol. There is, besides, an upper line on the scale, which exhibits the relation of spirit to water reckoned unity. Thus, above 10 per cent, over proof in the second line, we find in the upper line 8. From which we learn, that 8 of that spirit by bulk, will take 1 of water to bring it down to proof. At GO Fahr. I find that 10 over proof on Dicas corresponds to specific gravity - - 0.9085 3f over proof to 0.9160 Proof - - 0.9218 Now, by Gilpin's tables, this indicates a compound of 100 grains of alcohol 0.825, and 85 grains of water. But by Lowitz's table in Crell's Annals, the above specific gravity cor- responds to 48 alcohol of 0.791 at the tem- perature of 68, united to 52 of water, and cooled down to 60. Equal weights of that strong alcohol and water, give, at 60, a spe- cific gravity of 9175. By the act of par- liament of 1 762, the specific gravity of proof was fixed at 0.916. It is at present to water as 12 to 13, or = 0.923. See DISTILLA- TION. For the following table of the quantity of absolute alcohol, in spirits of different den- sities, we are indebted to Lowitz. 100 parts Specific gravity. 100 parts. Specific gravity. 100 parts. Specific gravity. Ale. Wat. At 68. At fcO". Ale. Wat. At 68. At 60*. Ale. Wat. At 68. At 60. 100 0.791 0.796 73 27 0.861 0.865 46 54 0.923 0.926 99 1 0-794 0.798 72 28 0.863 0.867 45 55 0.925 0.928 98 2 0.797 0.801 71 29 0.866 0.870 44 56 0.927 0.930 97 3 0.800 0.804 70 30 0.868 0.872 43 57 0.930 0.933 96 4 0.803 0.807 69 31 0.870 0.874 42 58 0.932 0.935 95 5 0.805 0.809 68 32 0.872 0.878 41 59 0.934 0.937 94 6 0.808 0.812 67 33 0.875 0.879 40 60 0.936 0.939 93 7 0.811 0.815 66 34 0.877 0.881 39 61 0.938 0.941 92 8 0.813 0.817 65 35 0.880 0.883 i 38 62 0.940 0.943 91 9 0.816 0.820 64 36 0.882 0.886 37 63 0.942 0.945 90 10 0.818 0.822 63 37 0.885 0.889 36 64 0.944 0.947 89 11 0.821 0.825 62 38 0.887 0.891 35 65 0.946 0.949 88 12 0.823 0.827 61 39 0.889 0.893 34 66 0.948 0.951 87 13 0.826 0.830 60 40 0.892 0.896 33 67 0.950 0.953 86 14 0.828 0.832 59 41 0.894 0.898 32 68 0.952 0.955 85 15 0.831 0.835 58 42 0.896 0-900 31 69 0.954 0.957 84 16 0.834 0.838 57 43 0.899 0.902 30 70 0.956 0.958 83 17 0.836 0.840 56 44 0.901 0.904 29 71 0.957 0.960 82 18 0.839 0.843 55 45 0.903 0.906 28 72 0.959 0.962 81 '19 0.842 0.846 54 46 0.905 0.908 27 73 0.961 0.963 80 20 0.844 0.848 53 47 0.907 0-910 26 74 0.963 0.965 79 21 0.847 0.851 52 48 0.909 0.912 25 75 0.965 0.967 78 22 0.849 0.853 51 49 0.912 0.915 24 76 0.966 0.968 77 23 0.851 0.855 50 50 0.914 0.917 23 77 0.968 0.970 76 24 0.853 0.857 49 51 0.917 0.920 22 78 0.970 0.972 75 25 i 0.856 0.860 48 52 0.919 0.922 21 79 0.971 0.973 74 26 1 0.859 0.863 47 53 0.921 0.924 20 80 0.973 0.974 ALC 125 ALC 100 parts. Specific gravity. 100 parts. Specific gravity. 100 parts. Specific gravity. Ale. Wat. At 68. At 60". Ale. Wat. At G8- At 60. Ale. Wat. At 68. At 60. 10 81 0.974 0.975 12 88 0.985 0.986 5 95 0.994 18 82 0.976 0.977 11 89 0.986 0.987 4 96 0.99o 17 83 0.977 0.978 10 90 0.98? 0.988 3 97 0.997 16 84 0.978 0.979 9 91 0.988 0.989 2 98 0-998 15 85 0.980 0.981 8 92 0.989 0.990 1 99 0.999 14 80 0.981 0.982 7 93 0.991 0.991 100 1.000 13 87 0-983 0.984 6 94 0.992 0.992 The most remarkable characteristic property of alcohol is its solubility or combination in all proportions with water, a property possessed by no other combustible substance, except the acetic spirit obtained by distilling the dry ace- tates. When it is burned in a chimney which communicates with the worm-pipe of a dis- tilling apparatus, the product, which is con- densed, is found to consist of water, which exceeds the spirit in weight about one-eighth part ; or more accurately, 100 parts of alco- hol, by combustion, yield 136 of water. If alcohol be burned in close vessels with vital air, the product is found to be water and car- bonic acid. Whence it is inferred that alcohol consists of hydrogen, united either to carbonic acid, or its acidifiable base ; and that the oxygen uniting on the one part with the hy- drogen, forms water ; and on the other with the base of the carbonic acid, forms that acid. The most exact experiments on this subject are those recently made by M. de Saussure. The alcohol he used had, at 62.8, a specific gravity of 0.8302 ; and by Richter's propor- tions, it consists of 13.8 water, and 86.2 of absolute alcohol. The vapour of alcohol was made to traverse a narrow porcelain tube ig- nited, from which the products passed along a glass tube about six feet in length, refrige- rated by ice. A little charcoal was deposited in the porcelain, and a trace of oil in the glass tube. The resulting gas being analyzed in an exploding eudiometer, with oxygen, was found to resolve itself into carbonic acid and water. Three volumes of oxygen disappeared for every two volumes of carbonic acid pro- duced ; a proportion which obtains in the analysis by oxygenation of olefiant gas. Now, as nothing resulted but a combustible gas of this peculiar constitution, and condensed wa- ter equal to ^%%% of the original weight of the alcohol, we may conclude that vapour of water and olefiant gas are the sole constituents of alcohol. Subtracting the 13.8 per cent, of water in the alcohol at the beginning of the experiment, the absolute alcohol of Richter will consist of 13-7 hydrogen, 51 98 carbon, and 34.32 oxygen. Hence M. Gay Lussac infers, that alcohol, in vapour, is composed of one volume olefiant gas, and one volume of the vapour of water, condensed by chemical affinity into one volume. The sp. gr. of olefiant gas is Of aqueous vapour is 0.97804 0.62500 Sum = 1.60304 And alcoholic vapour is = 1.6133 These numbers approach nearly to those which would result from two prime equiva- lents of olefiant gas, combined with one of water ; or ultimately, three of hydrogen, two of carbon, and one of oxygen. The analytical experiments on alcohol were among the most satisfactory of any which I made on vegetable products (see ANALYSIS VEGETABLE); for in repeated verifications the results agreed within one or at most two- hundredths of a grain. Alcohol, specific gra- vity 0.812, afforded me in 100 parts, 47-85 car- bon, 12.24 hydrogen, and 39.91 oxygen ; or referring the last two to the composition of water, 44.9 of it, with 7-25 oxygen in excess. Such alcohol would therefore seem to consist nearly of Carbon 3 atoms Hydrogen 6 Oxygen 2 . . 2.250 0.625 2.000 46.15 12.82 40.03 4.875 100.00 Or of 3 atoms of olefiant gas = 2.625 2 water = 2.250; and in volumes, 3 volumes olefiant gas = 0.9722 X 3 = 2.9166 4 aqueous vapour = 0.625 X 4 =2.5000. Thus alcohol 0.812, by the above analysis which I believe merits confidence, differs from M. Gay Lussac's view of absolute alcohol deduced from the experiments of M. de Saus- sure, in containing an additional volume of aqueous vapour. At the sp. gr. 0.814 alcohol would have exactly this atomic constitution. If the condensation be equal to the whole 3 volumes of olefiant gas, that is if the 7 vo- lumes of constituent gases become 4 of alcohol vapour, we shall have the specific gravity at this strength = 1.3722 ; the additional vo- lume of aqueous vapour producing necessarily this abatement in the density. A considerable number of the uses of this fluid as a menstruum will pass under our ob- servation in the various articles of this work. The mutual action between alcohol and acids produces a light, volatile, and inflammable- substance, called ether. See ETHER. Pure ALC 126 ALC alkalis unite with spirit of wine, and form al- kaline tinctures. Few of the neutral salts unite with this fluid, except such as contain ammonia. The carbonated fixed alkalis are not soluble in it. From the strong attraction which exists between alcohol and water, it unites with this last in saline solutions, and in most cases precipitates the salt. This is a pleasing experiment, which never fails to sur- prise those who are unacquainted with che- mical effects. If, for example, a saturated solution of nitre in water be taken, and an equal quantity of strong spirit of wine be poured upon it, the mixture will constitute a weaker spirit, which is incapable of holding the nitre in solution ; it therefore falls to the bottom instantly, in the form of minute crys- tals. The degrees of solubility of many neutral salts in alcohol have been ascertained by ex- periments made by Macquer, of which an ac- count is published in the Memoirs of the Turin Academy. The alcohol he employed was carefully freed from superabundant water by repeated rectifications, without addition of any intermediate substance.' The salts em- ployed in his experiments were previously de- prived of their water of crystallization by a careful drying. He poured into a matrass, upon each of the salts thus prepared, half an ounce of his alcohol, and set the matrass in a sand bath. When the spirit began to boil, he filtrated it while it was hot, and left it to cool, that he might observe the crystallizations which took place. He then evaporated the spirit, and weighed the saline residuums. He repeated these experiments a second time, with this difference, that instead of evapo- rating the spirit in which the salt had been digested, he set fire to it in order to examine the phenomena which its flame might exhibit The principal results of his experiments are subjoined. Quantity Salts soluble in of grains. 200 grains of spirit. 4 Nitrate of potash 5 Muriate of potash Sulphate of soda 15 Nitrate of soda Muriate of soda Sulphate of ammonia 108 Nitrate of ammonia 24 Muriate of ammonia 288 Nitrate of lime 288 Muriate of lime 84 Nitrate of silver 204 Muriate of mercury 4 Nitrate of iron 36 Muriate of iron 48 Nitrate of copper 43 Muriate of copper Peculiar phenomena of the flame. C Flame larger, higher, more ardent, yellow, and luminous. Large, ardent, yellow, and luminous. Considerably red. Yellow, luminous, detonating. Larger, more ardent, and reddish. None. Whiter, more luminous. None. 5 Larger, more luminous, red, and decrepi- { tating. Like that of the calcareous nitre. None. Large, yellow, luminous, and decrepitating. Red and decrepitating. More white, luminous, and sparkling. More white, luminous, and green, much smoke. The saline residuum became black and burnt. Fine green, white, and red figurations. Macquer accompanies the relation of his experiments with many judicious reflections, not easily capable of abridgment. The alcohol he employed in the above ex- periments had a specific gravity of 0.840. In analytical researches, alcohol affords frequently a valuable agent for separating salts from each other. We shall therefore introduce the fol- lowing additional table, derived chiefly from the experiments of Wenzel: 100 parts of alcohol dissolve of Nitrate of Cobalt, at Copper, Alumina, Lime, Magnesia, Muriate of Zinc, Alumina, 54.5 54.5 540.5 180.5 54.5 54.5 100 parts 100 100 125 290 100 100 Muriate of Magnesia, at 180.5- 547 parts. Iron, 180.5 100 Copper, 180.5 100 Acetate of Lead, 154 .5 100 At the boiling point, 100 parts of alcohol dissolve of muriate of lime 100 parts Nitrate of ammonia, 89 Corrosive sublimate, 88-8 Succinic acid, 74.0 Acetate of soda, 46.5 Nitrate of silver, 41.7 Refined sugar, 24.6 Boracic acid, 20.0 Nitrate of soda, 9.6 Acetate of copper, 7-5 Muriate of ammonia, 7- 1 Superarseniate of potash, 3.75 Oxalate of potash, 2.92 Nitrate of potash, . 2.08 ALC 127 ALC Muriate of potash, . . 2.08 Arseniate of soda, . .... 1.58 Arsenious acid, . . 1.25 Tartrate of potash, . . 0.42 It appears from the experiments of Kirwan, that dried muriate of magnesia dissolves more abundantly in strong than in weak alcohol. 100 parts of specific gravity 0.900, dissolve 21.25; of 0.848, 23.75; of 0.834, 36.25; and of 0.817, 50 parts. The same holds to a more limited extent with acetate of lime, 2.4 grains being soluble in 100 of the first alcohol, and 4.88. in 100 of the last. The other salts which he tried dissolved more sparingly in the stronger than in the weaker alcohol. The temperature of the spirit was generally 60. All deliquescent salts are soluble in alcohol. Alcohol holding the strontitic salts in solution, gives a flame of a rich purple. The cupreous salts and boracic acid give a green ; the solu- ble calcareous, a reddish ; the barytic, a yel- lowish. For the effect of other salts on the colour of the flame, see a preceding table. The alcohol of 0.825 has been subjected to a cold of 91 without congealing. But Mr. Hutton has given, in the Edinburgh En- cyclopaedia, article Cold, an account of his having succeeded in solidifying it by a cold of 110. The alcohol he employed had a density of 0.798 at 60^. His process has been kept secret. See ACID (SULPHUROUS) for a mode of freezing alcohol by the evaporation of that acid in its liquefied state. The boiling point of alcohol of 0. 825 is 1 76 Q . Alcohol of 0.810 boils at 173.5. For the force of its vapour at different temperatures, and its spe- cific heat, see CALORIC, and the Tables of Vapour at the end of the volume. When potassium and sodium are put in contact with the strongest alcohol, hydrogen is evolved. When chlorine is made to pass through alcohol hi a Woolfe's apparatus, there is a mutual action. Water, an oily- looking substance, muriatic acid, a little car- bonic acid, and carbonaceous matter, are the products. This oily substance does not red- den turnsole, though its analysis by heat shows it to contain muriatic acid. It is white, denser than water, has a cooling taste ana- logous to mint, and a peculiar, but not ethe- reous odour. It is very soluble in alcohol, but scarcely in water. The strongest alkalis hardly operate on it. It was at one time maintained, that alcohol did not exist in wines, but was generated and evolved by the heat of distillation. On this subject M. Gay Lussac made some decisive experiments. He agitated wine with litharge in fine powder, till the liquid became as limpid as water, and then saturated it with subcar- bonate of potash. The alcohol immediately separated and floated on the top. He distilled another portion of wine in vacua, at 59 Fahr. a temperature considerably below that of fer- mentation. Alcohol came over. Mr. Brande proved the same position by saturating wine with subacetate of lead, and adding potash. MM. Adam and Duportal have substituted for the redistillations used in converting wine or beer into alcohol, a single process of great elegance. From the capital of the still a tube is led into a large copper recipient. This is joined by a second tube to a second recipient, and so on through a series of four vessels, ar- ranged like a Woolfe's apparatus. The last vessel communicates with the worm of the first refrigeratory. This, the body of the still, and the two recipients nearest it, are charged with the wine or fermented liquor. When ebulli- tion takes place in the still, the vapour issuing from it communicates soon the boiling tempe- rature to the liquor in the two recipients, From these the volatilized alcohol will rise and pass into the third vessel, which is empty. After communicating a certain heat to it, a portion of the finer or less condensable spirit will pass into the fourth, and thence, in a little, into the worm of the first refrigeratory. The wine round the worm will likewise ac- quire heat, but more slowly. The vapour that in that event may pass uncondensed through the first worm, is conducted into a second, sur- rounded with cold water. Whenever the still is worked off it is replenished by a stopcock from the nearest recipient, which, in its turn, is filled from the second, and the second from the first worm tub. It is evident, from this arrangement, that by keeping the 3d and 4th recipients at a certain temperature, we may cause alcohol, of any degree of lightness, to form directly at the remote extremity of the apparatus. The utmost economy of fuel and time is also secured, and a better flavoured spirit is obtained. The arriere gout of bad spirit can scarcely be destroyed by infusion with charcoal and redistillation. In this mode of operating, the taste and smell are excellent, from the first. Several stills on the above principle have been constructed at Glasgow for the West India distillers, and have been found extremely advantageous. The excise laws do not permit their employment in the home trade. A very ingenious still on the above princi- ples has been recently invented by Mr. J. J. Saintmarc. It has the aspect of a copper tower, containing 9 or 10 stories, each apart- ment being divided from the one below by a horizontal partition or floor, pierced with open- ings or vertical pipes, admirably fitted for transferring to the highest stage, a very fine concentrated spirit in an uninterrupted opera- tion. The lowest floor alone is exposed to the naked fire, and the upper ones have their contents heated by the steam which it causes to ascend. The apparatus has an appearance of complica- tion, but I should think it quite simple and satisfactory in its performance. It has been made the su '^ci of a patent If Bnlpfair. ' i sublimation meet with the \ ALC 128 ALG I vapour of alcohol, a very small portion com- bines with it, which communicates a hydro- sulphurous smell to the fluid. The increased surface of the two substances appears to favour the combination. It had been supposed, that this was the only way in which they could be united ; but 31. Favre has lately asserted, that having digested two drams of flowers of sul- phur in an ounce of alcohol, over a gentle fire, not sufficient to make it boil, for twelve hours, he obtained a solution that gave twenty-three grains of precipitate. A similar mixture left to stand for a month in a place exposed to the solar rays, afforded sixteen grains of precipi- tate ; and another, from which the light was excluded, gave thirteen grains. If alcohol be boiled with one-fourth of its weight of sul- phur for an hour, and filtered hot, a small quantity of minute crystals will be deposited on cooling; and the clear fluid will assume an opaline hue on being diluted with an equal quantity of water, in which state it will pass die filter, nor will any sediment be deposited for several hours. The alcohol used in the last-mentioned experiment did v not exceed .840. Phosphorus is sparingly soluble hi alcohol, but in greater quantity by heat than in cold. The addition of water to this solution affords an opaque milky fluid, which gradually be- comes clear by the subsidence of the phos- phorus. Earths seem to have scarcely any action upon alcohol. Quicklime, however, produces some alteration in this fluid, by changing its flavour, and rendering it of a yellow colour. A small portion is probably taken up. Soaps are dissolved with great facility in alcohol, with which they combine more rea- dily than with water. None of the metals, or their oxides, are acted upon by this fluid. Resins, essential oils, camphor, bitumen, and various other substances, are dissolved with great facility in alcohol, from which they may be precipitated by the addition of water. From its property of dissolving resins, it becomes the menstruum of one class of varnishes. See VARNISH. Camphor is not only extremely soluble in alcohol, but assists the solution of resins in it. Fixed oils, when rendered drying by metallic oxides, are soluble in it, x as well as when com- bined with alkalis. Wax, spermaceti, biliary calculi, urea, and all the animal substances of a resinous nature, are soluble in alcohol ; but it curdles milk, coagulates albumen, and hardens the muscular fibre and coagulum of the blood. The uses of alcohol are various. As a solvent of resinous substances and essential oils, it is employed both in pharmacy and by the perfumer. When diluted with an equal quantity of water, constituting what is called proof spirit, it is used for extracting tinctures from vegetable and other substances, the al- cohol dissolving the resinous parts, asd the water the gummy. From giving a steady heat without smoke when burnt in a lamp, it was formerly much employed to keep water boiling on the tea-table. In thermometers, for measuring great degrees of cold, it is pre- ferable to mercury. It is in common use for preserving many anatomical preparations, and certain subjects of natural history ; but to some it is injurious, themolluscae for instance, the calcareous covering of which it in time corrodes. It is of considerable use too in chemical analysis, as appears under the dif- ferent articles to which it is applicable. From the great expansive power of alcohol, it has been made a question, whether it might not be applied with advantage in the working of steam-engines. From a series of experi- ments made by Betancourt, it appears, that the steam of alcohol has, in all cases of equal temperature, more than double the force of that of water ; and that the steam of alcohol at 174 F. is equal to that of water at 212 : thus there is a considerable diminution of the consumption of fuel, and where this is so ex- pensive as to be an object of great importance, by contriving the machinery so as to prevent the alcohol from being lost, it may possibly at some future time be used with advantage, if some other fluid of great expansive power, and inferior price, be not found more econo- mical. In my experiments on vapours, I found that the latent heat of that of alcohol is less than one half that of water ; for which reason the former would serve well for impelling the pistons of steam engines, were it not to act on the metals, which has been surmised. It was observed at the beginning of this article, that alcohol might be decomposed by transmission through a red-hot tube : it is also decomposable by the strong acids, and thus affords that remarkable product, ETHER, and OLEUM VINT.. ALE. See BEER. ALEMBIC, or STILL. This part of chemical apparatus, used for distilling or se- parating volatile products, by first raising them by heat, and then condensing them into the liquid state by cold, is of extensive use in a variety of operations. It is described under the article LABORATORY. ALEMBROTH SALT. Corrosive mu- riate of mercury is rendered much more soluble in water, by the addition of muriate of am- monia. From this solution crystals are sepa- rated by cooling, which were called sal-alem- broth by the earlier chemists, and appear to consist of ammonia, muriatic acid, and mer- cury. ALGAROTH (POWDER OF). Among the numerous preparations which the alche- mical researches into the nature of antimony have afforded, the powder of algaroth is one. When butter of antimony is thrown into ALK 129 ALK water, the greater part of the metallic oxide falls down in the form of a white powder, which is the powder of algaroth. It is vio- lently purgative and emetic in small doses of three or four grains. See ANTIMONY. ALKAHEST. The pretended universal solvent, or menstruum, of the ancient chemists. Kunckel has very well shown the absurdity of searching for a universal solvent, by asking, " If it dissolve all substances, in what vessels can it be contained ?" ALKALESCENT. Any substance in which alkaline properties are beginning to be developed, or to predominate, is termed alka- lescent. The only alkali usually observed to be produced by spontaneous decomposition is ammonia; and from their tendency to pro- duce this, some species of vegetables, particu- larly the cruciform, are styled alkalescent, as are some animal substances. See FERMEN- TATION (PUTHID). ALKALI. A term derived from kali, the Arabic name of a plant, from the ashes of which one species of alkaline substance can be extracted. Alkalis may be defined, those bodies which combine with acids, so as to neutralize or impair their activity, and produce salts. Acidity and alkalinity are therefore two correlative terms of one species of com- bination. When Lavoisier introduced oxy- gen as the acidifying principle, Morveau pro- posed hydrogen as the alkalifying principle, from its being a constituent of volatile alkali or ammonia. But the splendid discovery by Sir H. Davy, of the metallic bases of potash and soda, and of their conversion into alkalis, by combination with oxygen, has banished for ever that hypothetical conceit. It is the mode in which the constituents are combined, rather than the nature of the constituents themselves, which gives rise to the acid or alkaline condition. Some metals combined with oxygen in one proportion, produce a body possessed of alkaline properties, in another proportion of acid properties. And on the other hand, ammonia and prussic acid prove that both the alkaline and acid conditions can exist independent of oxygen. These observa- tions, by generalizing our notions of acids and alkalis, have rendered the definitions of them very imperfect. The difficulty of tracing a limit between the acids and alkalis is still in- creased, when we find a body sometimes per- forming the functions of an acid, sometimes of an alkali. Nor can we diminish this dif- ficulty by having recourse to the beautiful law discovered by Sir H. Davy, that oxygen and acids go to the positive pole, and hydrogen, alkalis, and inflammable bases to the negative pole. We cannot in fact give the name of acid to all the bodies which go to the first of these poles, and that of alkali to those that go to the second ; and if we wish to define the alkalis by bringing into view their electric energy, it would be necessary to compare them with the electric energy which is opposite to them. Thus we are always reduced to define alkalinity by the property which it has of satu- rating acidity, because alkalinity and acidity are two correlative and inseparable terms. M . Gay Lussac conceives the alkalinity which the me- tallic oxides enjoy, to be the result of two op- posite properties, the alkalifying property of the metal, and the acidifying of oxygen, modified both by the combination and by theproportions. The alkalis may be arranged into three classes : I st, Those which consist of a me- tallic basis combined with oxygen. These are three in number, potash, soda, and lithia. 2d, That which contains no oxygen, viz. am- monia. 3d, Those containing oxygen, hy- drogen, and carbon. In this class we have aconita, brucia, datura, delphia, hyosciama, morphia, strychnia,quinia, cinchonina, and per- haps some other truly vegetable alkali?. These are called by the German chemists, alkaloids. See VEGETABLE KINGDOM. The order of vegetable alkalis may be as numerous as that of vegetable acids. The earths, lime, barytes, and strontites, were enrolled among the alkalis by Fourcroy, but they have been kept apart by other systematic writers, and are called al- kaline earths. Besides neutralizing acidity, and thereby giving birth to salts, the first four alkalis have the following properties : 1st, They change the purple colour of many vegetables to a green, the reds to a purple, and the yellows to a brown. If the purple have been reddened by acid, alkalis restore the purple. 2d, They possess this power on vegetable colours after being saturated with carbonic acid, by which criterion they are distinguish- able from the alkaline earths. 3d, They have an acrid and urinous taste. 4th, They are powerful solvents or corro- sives of animal matter ; with which, as well as with fat oils in general, they combine, so as to produce neutrality. 5th, They are decomposed, or volatilized, at a strong red heat. th. They combine with water in every pro- portion, and also largely with alcohol. 'Jth, They continue to be soluble in water when neutralized with carbonic acid ; while the alkaline earths thus become insoluble. It is needless to detail at length Dr. Mur- ray's speculations on alkalinity. They seem to flow from a partial view of chemical phe- nomena. According to him, either oxygen or hydrogen may generate alkalinity, but the combination of both principles is necessary to give this condition its utmost energy. " Thus the class of alkalis will exhibit the same rela- tions as the class of acids. Some are com- pounds of a base with oxygen ; such are the greater number of the metallic oxides, and ALK 130 ALL probably of the earths. Ammonia is a com- pound of a base with hydrogen. Potash, soda, barytes, strontites, and probably lime, are com- pounds of bases with oxygen and hydrogen ; and these last, like the analogous order among the acids, possess the highest power." Now, surely, perfectly dry and caustic barytes, lime, and strontites, as well as the dry potash and soda obtained by Gay Lussac and Thenard, are not inferior in alkaline power to the same bodies after they are slacked or combined with water. 100 parts of lime destitute of hydrogen, that is, pure oxide of calcium, neutralize 78 parts of carbonic acid. But 132 parts of Dr. Murray's strongest lime, that is the hydrate, are required to produce the same alkaline ef- fect. If we ignite nitrate of barytes, we obtain, as is well known, a perfectly dry barytes, or protoxide of barium ; but if we ignite crys- tallized barytes, we obtain the same alkaline earth combined with a prime equivalent of water. These two different states of barytes were demonstrated by M. Berthollet in an ex- cellent paper published in the 2d volume of the Memoires D'Arcueil, so far back as 1809. " The first barytes" (that from crystallized barytes), says he, " presents all the characters of a combination ; it is engaged with a sub- stance which diminishes its action on other bodies, which renders it more fusible, and which gives it by fusion the appearance of glass. This substance is nothing else but water ; but in fact, by adding a little water to the second barytes (that from ignited nitrate), and by urging it at the fire, we give it the properties of the first." Page 47. 100 parts of barytes void of hydrogen, or dry barytes, neutralize 28 of dry carbonic acid. Whereas 1 1 If parts of the hydrate, or what Dr. Murray has styled the most energetic, are required to produce the same effect. In fact, it is not hydrogen which combines with the pure barytic earth, but hydrogen and oxygen in the state of water. The proof of this is, that when carbonic acid and that hydrate unite, the exact quantity of water is disengaged. The protoxide of barium, or pure barytes, has never been com- bined with hydrogen by any chemist ALKALI (MINERAL or FOSSIL). An old name of SODA. ALKALI (PHLOGISTICATED, or PRUSSIAN). When a fixed alkali is ignited with bullock's blood, or other animal sub- stances, and lixiviated, it is found to be in a great measure saturated with the prussic acid : from tfie theories formerly adopted respecting this combination, it was distinguished by the name of phlogisticated alkali. See ACID (PRUSSIC). ALKALI (VOLATILE). See AM- MONIA. ALKALIMETER. The name first given by M. Descroizilles to an instrument or mea- sure of his graduation, for determining the quantity of alkali in commercial potash and soda, by the quantity of dilute sulphuric acid of a known strength which a certain weight of them could neutralize. ALKANET. The alkanet plant is a kind of bugloss, which is a native of the warmer parts of Europe, and cultivated in some of our gardens. The greatest quantities are raised in Germany and France, particularly about Montpelier, whence we are chiefly supplied with the roots. These are of a superior quality to such as are raised in England. This root imparts an elegant deep red colour to pure alcohol, to oils, to wax, and to all unctuous substances. The aqueous tincture is of a dull brownish colour ; as is likewise the spirituous tincture when inspissated to the consistence of an extract. The principal use of alkanet root is, that of colouring oils, unguents, and lip- salves. Wax tinged with it, and applied on warm marble, stains it of a flesh colour, which sinks deep into the stone; as the spirituous tincture gives it a deep red stain. As the colour of this root is confined to the bark, and the small roots have more bark in proportion to their bulk than the great ones, these also afford most colour. ALLAG1TE. A carbo-silicate of man- ganese. ALLANITE. A mineral first recognized as a distinct species by Mr. Allen, of Edin- burgh, to whose accurate knowledge and splendid collection, the science of mineralogy has been so much indebted in Scotland. Its analysis and description, by Dr. Thomson, were published in the Cth volume of the Edin- burgh Phil. Trans. M. Giesecke found it in a granite rock in West Greenland. It is mas- sive and of a brownish-black colour. External lustre, dull ; internal, shining and resinous fracture small conchoidal opaque greenish- grey streak scratches glass and hornblende brittle spec. grav. 3.5 to 4.0. Froths and melts imperfectly before the blowpipe into a black scoria. It consists in 100 parts, of silica 35-4, oxide of cerium 33.9, oxide of iron 25.4, lime 9.2, alumina 4.1, and moisture 4.0. It has been also found crystallized in four, six, or eight-sided prisms. It closely resembles gadolinite, but may be distinguished from the thin fragments of the latter, being translucent on the edges, and of a fine green colour, whereas those of the former are commonly opaque and of a yellowish-brown. The ores of cerium analyzed by Berzelius, under the name of cerin, approach very closely in their compo- sition to allanite. ALLOCHROITE. A massive opaque mineral of a greyish, yellowish, or reddish colour. Quartz scratches it, but it strikes fire with steel. It has externally a glistening, and internally a glimmering lustre. Its fracture is uneven, and its fragments are translucent on the edges : sp. gr. 3.5 to 3.6. ALL 131 ALL It melts before the blowpipe into a black opaque enamel. Vauquelin's analysis is the following : Silica 35, lime 30.5, oxide of iron 17, alumina 8, carbonate of lime 6, oxide of manganese 3.5. M. Brogniart says it is abso- lutely infusible without addition, and that it requires a flux, as phosphate of soda or am- monia. With these it passes through a beautiful gradation of colours . It is covered at first with a species of enamel, which becomes on cooling reddish-yellow, then greenish, and lastly of a dirty yellowish-white. He represents it as pretty difficult to break. It was found by M. Dandrada in the iron mine of Virums, near Drammen in Norway. It is accompanied by carbonate of lime, protoxide of iron, and some- times brown garnets. ALLOPHANE. A mineral of a blue, and sometimes a green or brown colour, which oc- curs massive, or in imitative shapes. Lustre vitreous; fracture imperfectly conchoidal; transparent or translucent on the edges. Moderately hard, but very brittle. Sp. gr. 1.89. Composition, silica 21.92, alumina 32.2, lime 0.73, sulphate of lime 0.52, carbo- nate of copper 3.06, hydrate of iron 0.27, water 41.3. Stromeyer. It gelatinizes in acids. It is found in a bed of iron-shot limestone in greywacke slate, in the forest of Thuringia. It was called Riemannite. ALLAY, or ALLOY. Where any pre- cious metal is mixed with another of less value, the assayers call the latter the alloy, and do not in general consider it in any other point of view than as debasing or diminishing the value of the precious metal. Philosophical chemists have availed themelves of this term to distinguish all metallic compounds in general. Thus brass is called an alloy of copper and zinc ; bell-metal an alloy of copper and tin. Every alloy is distinguished by the metal which predominates in its composition, or which gives it its value. Thus English jew- ellery trinkets are ranked under alloys of gold, though most of them deserve to be placed under the head of copper. When mercury is one of the component metals, the alloy is called amalgam. Thus we have an amalgam of gold, silver, tin, &c. Since there are about 30 dif- derent permanent metals, independent of those evanescent ones that constitute the bases of the alkalis and earths, there ought to be about 870 different species of binary alloy. But only 132 species have been hitherto made and examined. Some metals have so little affinity for others, that as yet no compound of them has been effected, whatever pains have been taken. Most of these obstacles to alloying, arise from the difference in fusibility and volatility. Yet a few metals whose melting point is nearly the same, refuse to unite. It is obvious that two bodies will not combine, unless their affinity or reciprocal attraction be stronger than the co- hesive attraction of their individual particles. To overcome this cohesion of the solid bodies, and render affinity predominant, they must be penetrated by caloric. If one be very difficult of fusion, and the other very volatile, they will not unite unless the reciprocal attraction be exceedingly strong. But if their degree of fusibility be almost the same, they are easily placed in the circumstances most favourable for making an alloy. If we are therefore far from knowing all the binary alloys which are possible, we are still further removed from knowing all the triple, quadruple, &c., which may exist. It must be confessed, moreover, that this department of chemistry has been imperfectly cultivated. Besides, alloys are not, as far as we know, definitely regulated like oxides in the propor- tions of their component parts. 100 parts of mercury will combine with 4 or 8 parts of oxygen, to form two distinct oxides, the black and the red ; but with no greater, less, or intermediate proportions. But 100 parts of mercury will unite with I, 2, 3, or with any quantity up to 100 or 1000, of tin or lead. The alloys have the closest relations in their physical properties with the metals. They are all solid at the temperature of the atmosphere, except some amalgams : they possess metallic lustre, even when reduced to a coarse powder; are completely opaque, and more or less dense, according to the metals which compose them ; are excellent conductors of electricity ; cry- stallize more or less perfectly ; some are brit- tle, others ductile and malleable ; some have a peculiar odour; several are very sonorous and elastic. When an alloy consists of metals differently fusible, it is usually malleable while cold, but brittle while hot j as is exemplified in brass. The density of an alloy is sometimes greater, sometimes less than the mean density of its components, showing that, at the instant of their union, a diminution or augmentation of volume takes place. The relation between the expansion of the separate metals and that of their alloys has been investigated only in a very few cases. Alloys containing a volatile metal are decomposed, in whole or in part, at a strong heat. This happens with those of arsenic, mercury, tellurium, and zinc. Those that consist of two differently fusible metals may often be decomposed by exposing them to a temperature capable of melting only one of them. This operation is called eliquation. It is practised on the great scale to extract silver from copper. The argentiferous copper is melted with 3| times its weight of lead : and the triple alloy is exposed to a sufficient heat. The lead carries off the silver in its fusion, and leaves the copper under the form of a spongy lump. The silver is afterwards recovered from the lead by another operation. Some alloys oxidize more readily by heat and air, than when the metals are separately treated. Thus 3 of lead, and 1 of tin, at a dull red, burn visibly, and are almost instantly K2 ALL ALL oxidized. Each by itself, in the same circum- stances, would oxidize slowly, and without the disengagement of light has been given in some respectable works, for comparing the specific gravity that should re- sult from given quantities of two metals of The formation of an alloy must be regulated known densities alloyed together, supposing by the nature of the particular metals, to which therefore we refer. The degree of affinity between metals may be in some measure estimated by the greater or less facility with which, when of different degrees of fusibility or volatility, they unite, or with which they can after union be separated no chemical penetration or expansion of volume to take place. Thus it has been taught, that if gold and copper be united in equal weights, the computed or mathematical specific gravity of the alloy is the arithmetical mean of the two specific gravities. This error was pointed out by me in a paper published in the 7th by heat. The greater or less tendency to number of the Journal of Science and the separate into different proportional alloys, by Arts ; and the correct rule was at the same long continued fusion, may also give some information on this subject. Mr. Hatchett remarked, in his admirable researches on metallic alloys, that gold made standard with the usual precautions by silver, copper, lead, antimony, &c. and then cast into vertical bars, was by no means an uniform compound ; but that the top of the bar, corresponding to the metal at the bottom of the crucible, contained time given. The details belong to the article Specific Gravity ; but the rule merits a place here . The specific gravity of the alloy is found by dividing the sum of the weights by the sum of the volumes, compared to water, reckoned unity. Or in another form, the rule may be stated thus : Multiply the sum of the weights into the product of the two specific gravities for a numerator, and multiply each the larger proportion of gold. Hence, for specific gravity into the weight of the other thorough combination, two red-hot crucibles body, and add the two products together for a should be employed ; and the liquefied metals J : ** ""- >- - * should be alternately poured from the one into the other. And to prevent unnecessary oxi- denominator. The quotient obtained by divid- ing the numerator by the denominator, is the true computed mean specific gravity ; and that dizement by exposure to air, the crucibles found by experiment, being compared with it, should contain, besides the metal, a mixture of common salt and pounded charcoal. The melted alloy should also be occasionally stirred up with a rod of pottery. The most direct evidence of a chemical will show whether expansion or condensation of volume has attended the chemical combina- tion. Gold having a specific gravity of 19.36, and copper of 8.87, being alloyed in equal weights, give on the fallacious rule change having taken place in the two metals of the aritmetical mean of the densities, by combination, is when the alloy melts at a much lower temperature than the fusing points of its components. Iron, which is nearly in- fusible, when alloyed with gold acquires almost the fusibility of this metal. Tin and lead form solder, an alloy more fusible than either of its components ; but the triple compound of tin, lead, and bismuth, is most remarkable on this account. The analogy is here strong, with the increase of solubility which salts acquire 19-36 + 8.87 = 14.11 ; whereas the rightly calculated mean specific gravity is only 12.16. It is evident, that by comparing the former number with chemical experiment, we should be led to infer a prodigious condensation of volume beyond. what really occurs. A circumstance was observed by Mr. Hatchett to influence the density of metals, which a by mixture, as is exemplified in the uncrys- P riori mi g ht be thought unimportant. When a bar of gold was cast in a vertical position, the density of the metal at the lower end of the bar was greater than that of the top, in the pro- portion of 17.364 to 17.035. Are we to infer that melted metal is a compressible fluid, or rather, that particles passing into the solid state under pressure, exert their cohesive at- traction with adventitious strength ? Under the title metal, a tabular view of metallic combinations will be found, and under that of tallizable residue of saline solutions, or mother waters, as they are called. Sometimes two metals will not directly unite, which yet, by the intervention of a third, are made to com- bine. This happens with mercury and iron, as has been shown by Messrs. Aikin, who effected this difficult amalgamation by previ- ously uniting the iron to tin or zinc. The tenacity of alloys is generally, though not always, interior to the mean of the sepa- rate metals. One part of lead will destroy the the particular metal, the requisite information compactness and tenacity of a thousand of gold. about its all ys. 1 --"-- ALLUVIAL FORMATIONS, in geo- logy, are recent deposits in valleys or in plains, of the detritus of the neighbouring mountains. Gravel, loam, clay, sand, brown coal, wood coal, bog iron ore, and calc tuff, compose the alluvial deposits. The gravel and sand some- times contain gold and tin, if the ores exist Brass made with a small proportion of zinc, is more ductile than copper itself; but when one-third of zinc enters into its composition, it becomes brittle. In common cases, the specific gravity affords a good criterion whereby to judge of the pro- portion in an alloy, consisting of two metals of different densities. But a very fallacious rule in the adjoining mountains. Petrified wood ALO 133 ALU and animal skeletons are found in the alluvial clays and sand. ALMANDINE. Precious garnet. ALMONDS. Almonds consist chiefly of an oil of the nature of fat oils, together with farinaceous matter. The oil is so plentiful, and so loosely combined or mixed with the other principles, that it is obtained by simple pressure, and part of it may be squeezed out with the fingers. Five pounds and a half have yielded one pound six ounces of oil by cold expression, and three quarters of a pound more on heating them. There are two kinds of almonds, the sweet and bitter. The bitter almonds yield an oil as tasteless as that of the other, all the bitter matter remaining in the cake after the expression. Great part of the bitter matter dissolves by digestion, both in watery and spirituous liquors ; and part arises with both in distillation. R ember obtained from them l-3d of watery extract, and 3-32ds of spirituous. Bitter almonds are poisonous to birds, and to some animals. A water dis- tilled from them, when made of a certain de- gree of strength, has been found from experi- ment to be poisonous to brutes ; and there are instances of cordial spirits impregnated with them being poisonous to men. It seems, in- deed, that the vegetable principle of bitterness in almonds and the kernels of other fruits, is destructive to animal life, when separated by distillation from the oil and farinaceous matter. The distilled water from laurel leaves appears to be of this nature, and its poisonous effects are well known. See ACID (Paussic). Sweet almonds are made into an emulsion by trituration with water, which on standing ^eparates a thick cream floating on the top. The emulsion may be curdled by heat, or the addition of alcohol or acids. The whey con- tains gum, extractive matter, and sugar, ac- cording to Professor Proust ; and the curd, when washed and dried, yields oil by expres- sion, and afterward by distillation the same products as cheese. The whey is a good di- luent. Prussic or hydrocyanic acid is the deleteri- ous ingredient in bitter almonds. The best remedy, after emetics, is a combination of sul- phate of iron with bicarbonate of potash. ALOES. This is a bitter juice, extracted from the leaves of a plant of the same name. Three sorts of aloes are distinguished in the shops by the names of aloe soccotrina, aloe hepatica, and aloe caballina. The first deno- mination, which is applied to the purest kind, is taken from the island of Zocotora ; the se- cond, or next in quality, is called hepatica, from its liver colour ; and the third, caballina, from the use of this species being confined to horses. These kinds of aloes are said to differ only in purity, though, from the difference of their flavours, it is probable that they may be obtained in some instances from different spe- cies of the same plant. It is certain, however, that the different kinds are all prepared at Morviedro in Spain, from the same leaves of the common aloe. Deep incisions are made in the leaves, from which the juice is suffered to flow ; and this, after decantation from its sedi- ment, and inspissation in the sun, is exposed to sale in leathern bags by the name of socco- trine aloes. An additional quantity of juice is obtained by pressure from the leaves ; and this, when decanted from its sediment and dried, is the hepatic aloes. And lastly, a portion of juice is obtained by strong pressure of the leaves, and is mixed with the dregs of the two preceding kinds to form the caballine aloes. The first kind is said to contain much less resin. The principal characters of good aloes are these : it must be glossy, not very black, but brown ; when rubbed or cut, of a yellow colour; compact, but easy to break; easily soluble; of an unpleasant peculiar smell, which cannot be described, and an extremely bitter taste. Aloes appears to be an intimate combination of gummy resinous matter, so well blended together, that watery or spirituous solvents, separately applied, dissolve the greater part of both. It is not determined whether there be any difference in the medical properties of these solutions. Both are purgative, as is likewise the aloes in substance ; and, if used too freely, are apt to prove heating, and produce hemor- rhoidal complaints. Braconnot imagines he has detected in aloes a peculiar principle, similar to the bitter resi- nous, which Vauquelin has found in many febrifuge barks. The recent juice of the leaves absorbs oxygen, and becomes a fine reddish- purple pigment. ALUDEL. The process of sublimation differs from distillation in the nature of its product, which, instead of becoming condensed in a fluid, assumes the solid state, and the form of the receivers may of course be very different The receivers for sublimates are of the nature of chimnies, in which the elastic products are condensed, and adhere to their internal surface. It is evident that the head of an alembic will serve very well to receive and condense such sublimates as are not very volatile. The earlier chemists, whose notions of simplicity were not always the most perfect, thought proper to use a number of similar heads, one above the other, communicating in succession by means of a perforation in the superior part of each, which received the neck of the capital immediately above it These heads differing in no respect from the usual heads of alembics, excepting in their having no nose or beak, and in the other circum- stances here mentioned, were called aludels. They are seldom now to be seen in chemical laboratories, because the operations of this art may be performed with greater simplicity ALU 134 ALU of instruments, provided attention be paid to the heat and other circumstances. ALUM. See ALUMINA, Sulphate of. ALUM-EARTH. A massive mineral, of a blackish-brown colour, a dull lustre, an earthy and somewhat slaty fracture, sectile, and rather soft. By Klaproth's analysis it contains, charcoal 19.6*5, silica 40, alumina 16, oxide of iron 6.4, sulphur 2-84, sulphates of lime and potash each 1.5, sulphate of iron 1.8, magnesia and muriate of potash 0.5, and water 10.75. ALUM-SLATE. 1. Common. This mi- neral occurs both massive and in insulated balls of a greyish-black colour, dull lustre, straight slaty fracture, tabular fragments, streak coloured like itself. Though soft, it is not very brittle. Effloresces, acquiring the taste of alum. 2. Glossy Alum-slate. A massive mineral of a bluish-black colour. The rents display a variety of lively purple tints. It has a semi- metallic lustre in the fracture, which is straight, slaty, or undulating. There is a soft variety of it, approaching in appearance to slate clay. By exposure to air its thickness is prodigiously augmented by the formation of a saline efflor- escence, which separates its thinnest plates. These afterwards exfoliate in brittle sections, causing entire disintegration. A L UM INA. One of the primitive earths, which, as constituting the plastic principle of all clays, loams, and boles, was called argil or the argillaceous earth, but now, as being ob- tained in greatest purity from alum, is styled alumina. It was deemed elementary matter till Sir H. Davy's celebrated electro-chemical researches led to the belief of its being, like barytes and lime, a metallic oxide. The purest native alumina is found in the oriental gems, the sapphire and ruby. They consist of nothing but this earth, and a small portion of colouring matter. The native porcelain clays or kaolins, however white and soft, can never be regarded as pure alumina- They usually contain fully half their weight of silica, and frequently other earths. To obtain pure alumina we dissolve alum in 20 times its weight of water, and add to it a little of the solution of carbonate of soda, to throw down any iron which may be present. We then drop the supernatant liquid into a quantity of the water of ammonia, taking care not to add so much of the aluminous solution as will saturate the ammonia. The volatile alkali unites with the sulphuric acid of the alum, and the earthy basis of the latter is sepa- rated in a white spongy precipitate. This must be thrown on a niter, washed, or edul- corated, as the old chemists expressed it, by repeated affusions of water, and then dried. Or if an alum, made with ammonia instead of potash, as is the case with some French alums, can be got, simple ignition dissipates its acid and alkaline constituents, leaving pure alumina. Alumina prepared by the first process is white, pulverulent, soft to the touch, adheres to the tongue, forms a smooth paste without grittiness in the mouth, insipid, inodorous, produces no change in vegetable colours, inso- luble in water, but mixes with it readily in every proportion, and retains a small quantity with considerable force; is infusible in the strongest heat of a furnace, experiencing merely a condensation of volume and conse- quent hardness, but is in small quantities melted by the oxyhydrogen blowpipe. Its specific gravity is 2.000, in the state of powder, but by ignition it is augmented. Every analogy leads to the belief that alu- mina contains a peculiar metal, which may be called aluminum. The first evidences ob- tained of this position are presented in Sir H. Davy's researches. Iron negatively electrified by a very high power being fused in contact with pure alumina, formed a globule whiter than pure iron, which effervesced slowly in water, becoming covered with a white powder. The solution of this in muriatic acid, decom- posed by an alkali, afforded alumina and oxide of iron. By passing potassium in vapour through alumina heated to whiteness, the greatest part of the potassium became con- verted into potash, which formed a coherent mass with that part of the alumina not decom- pounded ; and in this mass there were numer- ous grey particles, having the metallic lustre, and which became white when heated in the air, and which slowly effervesced in water. In a similar experiment made by the same illus- trious chemist, a strong red heat only being applied to the alumina, a mass was obtained, which took fire spontaneously by exposure to air, and which effervesced violently in water. This mass was probably an alloy of aluminum and potassium. The conversion of potas- sium into its oxide, dry potash, by alumina, proves the presence of oxygen in the latter. When regarded as an oxide, Sir H. Davy estimates its oxygen and basis to be to one another as 15 to 33 ; or as 10 to 22. The prime equivalent of alumina would thus appear to be 1.0 -f 2.2 3.2. But Berzelius's analysis of sulphate of alu- mina seems to indicate 2.136 as the quantity of the earth which combines with 5 of the acid. Hence aluminum will come to be represented by 2.136 1 = 1.136. W^e shall presently show that his analysis, both of alum and sul- phate of alumina, may be reconciled nearly to Sir H. Davy's equivalent prime == 3.2. That of aluminum will become of course 2.2. Alumina which has lost its plasticity by ignition, recovers it by being dissolved in an acid or alkaline menstruum, and then preci- pitated. In this state it is culled a hydrate, for when dried in a steam heat it retains much ALU 155 ALU water ; and therefore resembles in composition wavellite, a beautiful mineral, consisting al- most entirely of alumina, with about 28 per cent, of water. Alumina is widely diffused in nature. It is a constituent of every soil, and of almost every rock. It is the basis of porcelain, pottery, bricks, and crucibles. Its affinity for vegetable colouring matter is made use of in the preparation of lakes, and in the arts of dyeing and calico printing. Native combinations of alumina constitute the ful- ler's earth, ochres, boles, pipe- clays, &c. ALUMINA (SALTS of). These salts have the following general characters : 1. Most of them are very soluble in water, and their solutions have a sweetish acerb taste. 2. Ammonia throws down their earthy base, even though they have been previously acidu- lated with muriatic acid. 3. At a strong red heat they give out a por- tion of their acid. 4. Phosphate of ammonia gives a white precipitate. 5. Hydriodate of potash produces a floccu- lent precipitate of a white colour, passing into a permanent yellow. 6. They are not affected by oxalate of am- monia, tartaric acid, ferroprussiate of potash, or tincture of galls ; by the first two tests they are distinguishable from yttria, and by the last two from that earth and glucina. 7. If bisulphate of potash be added to a solution of an aluminous salt, moderately concentrated, octahedral crystals of alum will form. Acetate of Alumina. By digesting strong acetic acid on newly precipitated alumina, this saline combination can be directly formed. Vinegar of ordinary strength scarcely acts on the earth. But the salt is seldom made in this way. It is prepared in large quantities for the calico printers, by decomposing alum with acetate of lead ; or more economically with aqueous acetate of lime, having a specific gravity of about 1.050 ; a gallon of which, equivalent to nearly half a pound avoirdupoise of dry acetic acid, is employed for every 2f Ib. of alum. A sulphate of lime is formed by complex affinity, which precipitates, and an acetate of alumina floats above. The above proportion of alum is much beyond the equi- valent quantity ; and the specific gravity of the liquid is consequently raised by the excess of salt. It is usually 1.080. By careful evaporation capillary crystals are formed, which readily deliquesce. M. Gay Lussac made some curious observations on the solu- tions of this salt. Even when made with cold saturated solutions of alum and acetate of lead, and consequently but little concentrated, it becomes turbid when heated to 122 Fahr. ; and at a boiling heat a precipitate falls of about one-half of the whole salt. On cooling it is redissolved. This decomposition by heat, which would be prejudicial to the calico printer, is prevented by the excess of alum which is properly used in actual practice. M. Gay Lussac thinks this phenomenon has con- siderable analogy with the coagulation of albu- men by heat ; the particles of the water, and of the solid matter, being carried by the heat out of their sphere of activity, separate. It is probably a subacetate which falls down, as well as that which is obtained by drying the crystals. Wenzel's analysis of acetate of alumina gives 73.81 acid to 26.19 base in 100 parts. If we suppose it to consist, like the sulphate, of three primes of acid to two of alumina, we shall have for its equivalent proportions, 20 of dry acid + 6.4 earth or 75.8 -f 24.2 100. As alum contains, in round numbers, about l-9th of earthy base, 8 oz. of real acetic acid present in the gallon of the redistilled pyrolignous, would require about 2i Ibs. of alum for exact decompo- sition. The excess employed is found to be useful. The affinity between the constituents of this salt is very feeble. Hence the attraction of cotton fibre for alumina, aided by a moderate heat, is sufficient to decompose it. The following salts of alumina are inso- luble in water : Arseniate, borate, phosphate, tungstate, mellate, saclactate, lithate, malate, camphorate. The oxalate is uncrystallizable. It consists of 56 acid and water, and 44 alu- mina. The tartrate does not crystallize. But the tartrate of potash and alumina is remark- able, according to Thenard, for yielding no precipitate, either by alkalis or alkaline car- bonates. The supergallate crystallizes. There seems to be no dry carbonate. A supernitrate exists very difficult to crystallize. Its specific gravity is 1.645. A moderate heat drives off the acid. The muriate is easily made by di- rting muriatic acid on gelatinous alumina, is colourless, astringent, deliquescent, un- crystallizable, reddens turnsole, and forms a gelatinous mass by evaporation. Alcohol dis- solves at 60 half its weight of this salt A dull red heat separates the acid from the alumina. Its composition is, according to Bucholz, 29.8 acid, 30.0 base, 40.2 water, in 100 parts. Sulphate of alumina exists under several modifications. The simple sulphate is easily made, by digesting sulphuric acid on pure clay. The salt thus formed crystallizes in thin soft plates, having a pearly lustre. It has an astringent taste, and is so soluble in water as to crystallize with difficulty. When moderately heated the water escapes, and, at a higher temperature, the acid. Berzelius has chosen this salt for the purpose of determining the equivalent of alumina. He considers the dry sulphate as a compound of 100 parts of sulphuric acid with 42-722 earth. This makes the equivalent 21.361, oxygen being reckoned 10, if we consider it a compound of a prime ALU 136 ALU proportion of each. But if we regard it as consisting of 3 of acid and 2 of base, we shall have 32.0 for the prime equivalent of alumina. The reason for assigning this number will appear in treating of the next salt. ALUM. This important salt has been the object of innumerable researches both with regard to its fabrication and composition. It is produced, but in a very small quantity, in the native state; and this is mixed with heterogeneous matters. It effloresces in va- rious forms upon ores during calcination, but it seldom occurs crystallized. The greater part of this salt is factitious, being extracted from various minerals called alum ores, such as, 1. Sulphurated clay. This constitutes the purest of all aluminous ores, namely, that of la Tolfa, near Civita Vecchia, in Italy. It is white, compact, and as hard as indurated clay, whence it is called petra aluminaris. It is tasteless and mealy; one hundred parts of this ore contain above forty of sulphur and fifty of clay, a small quantity of potash, and a little iron. Bergman says it contains forty- three of sulphur in one hundred, thirty -five of clay, and twenty-two of siliceous earth. This ore is first torrefied to acidify the sulphur, li which then acts on the clay, and forms the alum. 2. The pyritaceous clay, which is found at Schwemsal, in Saxony, at the depth of ten or twelve feet. It is a black and hard, but brittle substance, consisting of clay, pyrites, and bitumen. It is exposed to the air for two years ; by which means the pyrites is decom- posed, and the alum is formed. The alum ores of Hesse and Liege are of this kind ; but they are first torrefied, which is said to be a disadvantageous method. 3. The schistus aluminaris contains a vari- able proportion of petroleum and pyrites inti- mately mixed with it. When the last are in a very large quantity, this ore is rejected as containing too much iron. Professor Berg- man very properly suggested, that by adding a proportion of clay, this ore may turn out advantageously for producing alum. But if the petrol be considerable, it must be torrefied. The mines of Becket in Normandy, and those of Whitby in Yorkshire, are of this 4. Volcanic aluminous ore. Such is that of Solfaterra, near Naples. It is in the form of a white saline earth, after it has effloresced in the air ; or else it is in a stony form. 5. Bituminous alum ore is called shale, and is in the form of a schistus, impregnated with so much oily matter, or bitumen, as to be inflammable. It is found in Sweden, and also in the coal mines at Whitehaven, and elsewhere. Chaptal has fabricated alum on a large scale from its component parts. For this purpose he constructed a chamber 91 feet long, 48 wide, and 31 high in the middle. The walls are of common masonry, lined with a pretty thick coating of plaster. The floor is paved with bricks, bedded in a mixture of raw and burnt clay ; and this pavement is covered with another, the joints of which overlap those of the first, and instead of mortar the bricks are joined with a cement of equal parts of pitch, turpentine, and wax, which, after having been boiled till it ceases to swell, is used hot The roof is of v/ood, but the beams are very close together, and grooved lengthwise, the inter- mediate space being filled up by planks iitted into the grooves, so that the whole is put to- gether without a nail. Lastly, the whole of the inside is covered with three or four succes- sive coatings of the cement above-mentioned, the first being laid on as hot as possible ; and the outside of the wooden roof was varnished in the same manner. The purest and whitest clay being made into a paste with water, and formed into balls half a foot in diameter, these are calcined in a furnace, broken to pieces, and a stratum of the fragments laid on the floor. A due proportion of sulphur is then ignited in. the chamber, in the same manner as for the fabrication of sulphuric acid; and the frag- ments of burnt clay, imbibing this as it forms* begin after a few days to crack and open, and exhibit an efflorescence of sulphate of alumina. When the earth has completely effloresced, it is taken out of the chamber, exposed for some time in an open shed, that it may be the more, intimately penetrated by the acid, and is then lixiviated and crystallized in the usual manner. The cement answers the purpose of lead on this- occasion very effectually, and, according to M. Chaptal, costs no more than lead would at three farthings a pound. Curaudau has lately recommended a process, for making alum without evaporation. One hundred parts of clay and five of muriate of soda are kneaded into a paste with water, and formed into loaves. With these a reverbera- tory furnace is filled, and a brisk fire is kept up for two hours. Being powdered, and put into a sound cask, one-fourth of their weight of sulphuric acid is poured over them by de- grees, stirring the mixture well at each ad- dition. As soon as the muriatic gas is dis- sipated, a quantity of water equal to the acid is added, and the mixture stirred as before. When the heat is abated, a little more water is poured in ; and this is repeated till eight or ten times as much water as there was acid is added. When the whole has settled, the clear liquor is drawn off into leaden vessels, and a quantity of water equal to this liquor is poured on the sediment. The two liquors being mixed, a solution of potash is added to them, the alkali in which is equal to one-fourth of the weight of the sulphuric acid. Sulphate of potash may be used ; but twice as much of this as of the alkali is necessary. After a cer- tain time the liquor by cooling affords crystals of alum equal to three times the weight of the ALU 137 ALU acid used. It is refined by dissolving it in the smallest possible quantity of boiling water. The residue may be washed with more water, to be employed in lixiviating a fresh portion of the ingredients. As the mother water still contains alum, with sulphate of iron very much oxided, it is well adapted to the fabrication of prussian blue. This mode of making alum is parti- cularly advantageous to the manufacturers of prussian blue, as they may calcine their clay at the same time with their animal matters without additional expense : they will have no need in this case to add potash ; and the pre- sence of iron, instead of being injurious, will be very useful. If they wished to make alum for sale, they might use the solution of sul- phate of potash arising from the washing of their prussian blue, instead of water, to dis- solve the combination of alumina and sulphu- ric acid. The residuums of distillers of aquafortis are applicable to the same purposes, as they contain the alumina and potash requisite, and only require to be reduced to powder, sprin- kled with sulphuric acid, and lixiviated with water, in the manner directed above. The mother waters of these alums are also useful in the fabrication of prussian blue. As the residuum of aquafortis contains an over-pro- portion of acid, it will be found of advan- tage to add an eighth of its weight of clay cal- cined as above. The most extensive alum manufactory in Great Britain is at Hurlett, near Paisley, on the estate of the Earl of Glasgow. The next in magnitude is at Whitby : of whose state and processes an instructive account was pub- lished by Mr. Winter in the 25th volume of Nicholson's Journal. The stratum of alu- minous schistus is about 29 miles in width, and it is covered by strata of alluvial soil, sandstone, ironstone, shell, and clay. The alum schist is generally found disposed in horizontal laminae. The upper part of the rock is the most abundant in sulphur; so that a cubic yard taken from the top of the stratum is 5 times more valuable than the same bulk 100 feet below. If a quantity of the schistus be laid in a heap, and moistened with sea-water, it will take fire spontaneously, and will continue to burn till the whole inflammable matter be consumed. Its colour is bluish-grey. Its sp. gravity is 2.48. It imparts a bituminous principle to alcohol. Fused with an alkali, muriatic acid precipitates a large proportion of silex. The expense of digging and removing to a distance of 200 yards one cubic yard of the schistose rock, is about sixpence-halfpenny. A man can earn from 2*. 6d. to 3*. a-day. The rock, broken into small pieces, is laid on a horizontal bed of fuel, composed of brush- wood, &c. When about 4 feet in height of the rock is piled on, fire is set to the bottom, and fresh rock continually poured upon the pile. This is continued uutil the calcined heap be raised to the height of 90 or 100 feet. Its horizontal area has also been progressively extended at the same time, till it forms a great bed nearly 200 feet square, having about 100,000 yards of solid measurement. The rapidity of the combustion is allayed by plas- tering up the crevices with small schist moist- ened. Notwithstanding of this precaution, a great deal of sulphuric or sulphurous acid is dissipated. 130 tons of calcined schist pro- duce on an average 1 ton of alum. This re- sult has been deduced from an average of 150,000 tons. The calcined mineral is digested in water contained in pits that usually contain about 60 cubic yards. The liquid is drawn off into cisterns, and afterwards pumped up again upon fresh calcined mine. This is repeated until the specific gravity becomes 1.15. The half -exhausted schist is then covered with water to take up the whole soluble matter. The strong liquor is drawn off into settling cisterns, where the sulphate of lime, iron, and earth are deposited. At some works the liquid is boiled, which aids its purification. It is then run into leaden pans 10 feet long, 4 feet 9 inches wide, 2 feet 2 inches deep at the one end, and 2 feet 8 inches at the other. This slope makes them be easily emptied. Here the liquor is concentrated at a boiling heat. Every morning the pans are emptied into a settling cistern, and a solution of muriate of potash, either pretty pure from the manufac- turer, or crude and compound from the soap- boiler, is added. The quantity of muriate necessary is determined by a previous experi- ment in a basin, and is regulated for the work- men by the hydrometer. By this addition the pan liquor, which had acquired a specific gra- vity of 1.4 or 1.5, is reduced to 1.35. After being allowed to settle for two hours, it is run off into the coolers to be crystallized. At a greater sp. gravity than 1.35, the liquor, in- stead of crystallizing, would, when it cools, present us with a solid magma, resembling grease. Urine is occasionally added, to bring it down to the proper density. After standing 4 days the mother waters are drained off, to be pumped into the pans on the succeeding day. The crystals of alum are washed in a tub, and drained. They are then put into a lead pan, with as much water as will make a saturated solution at the boiling point. Whenever this is effected, the solution is run off into casks. At the end of 10 or 16 days, the casks are unhooped and taken asun- der. The alum is found exteriorly in a solid cake, but in the interior cavity, in large pyra- midal 'crystals, consisting of octahedrons, in- serted successively into one another. This last ALU 138 ALU process is called roching. Mr. Winter says, that 22 tons of muriate of potash will produce 100 tons of alum, to which 31 tons of the black ashes of the soap-boiler, or 73 of kelp, are equivalent. Where much iron exists in the alum ore, the alkaline muriate, by its decomposition, gives birth to an uncrystal- lizable muriate of iron. The alum manufac- tured in the preceding mode is a sulphate of alumina and potash. There is another alum which exactly resembles it. This is a sulphate of alumina and ammonia. Both crystallize in regular octaedrons, formed by two four-sided pyramids joined base to base. Alum has an astringent sweetish taste. Its sp. gravity is about 1.71. It reddens the vegetable blues. It is soluble in 16 parts of water at 60, and in fths of its weight at 212. It effloresces superficially on exposure to air, but the interior remains long unchanged. Its water of crystallization is sufficient at a gentle heat to fuse it. If the heat be increased it froths up, and loses fully 45 per cent, of its weight in water. The spongy residue is called burnt or calcined alum, and is used by sur- geons as a mild escharotic, A violent heat separates a great portion of its acid. Alum was thus analyzed by Berzelius : 1st, 20 parts (grammes) of pure alum lost by the heat of a spirit lamp 9 parts, which gives 45 per cent of water. The dry salt was dissolved in water, and its acid precipitated by muriate of barytes ; the sulphate of which, obtained after ignition, weighed 20 parts ; indicating in 100 parts 34.3 of dry sulphuric acid. 2d, Ten parts of alum were dissolved in water, and di- gested with an excess of ammonia. Alumina, well washed and burnt, equivalent to 10.67 per cent, was obtained. In another experi- ment, 10.86 per cent, resulted. 3d, Ten parts of alum dissolved in water, were digested with carbonate of strontites, till the earth was com- pletely separated. The sulphate of potash, after ignition, weighed 1.815, corresponding to 0.981 potash, or in 100 parts to 9.81. Alum, therefore, consists of Sulphuric acid 34.33 Alumina 10.86 Potash 9.81 Water 45.00 100.00 or, Sulphate of alumina 36.85 Sulphate of potash 18.15 Water 45.00 100.00 Thenard's analysis, Ann. de Chimie, vol. 59. or Nicholson's Journal, vol. 18. coincides perfectly with that of Berzelius in the product of sulphate of barytes. From 400 parts of alum, he obtained 490 of the ignited barytic salt ; but the alumina was in greater propor- tion, equal to 12.54 per cent, and the sulphate of potash less, or 15.7 in 100 parts. Vauquelin, in his last analysis, found 48.58 water ; and by Thenard's statement there are indicated 34.23 dry acid, 7-14 potash, 12.54 alumina, 46.09 water, 100.00 If we rectify Vauquelin's erroneous esti- mate of the sulphate of barytes, his analysis will also coincide with the above. Alum, therefore, differs from the simple sulphate of alumina previously described, which consisted of 3 prime equivalents of acid and 2 of earth, merely by its assumption of a prime of sul- phate of potash. It is probable that all the aluminous salts have a similar constitution. It is to be observed, however, that the number 34.36 resulting from the theoretic proportions, is, according to Gilbert's remarks on the essay of Berzelius, the just representation of the dry acid in 100 of sulphate of barytes, by another analysis, which makes the prime of barytes 9.57- Should ammonia be suspected in alum, it may be detected, and its quantity estimated by mixing quick lime with the saline solu- tion, and exposing the mixture to heat in a retort, connected with a Woolfe's apparatus. The water of ammonia being afterwards satu- rated with an acid, and evaporated to a dry salt, will indicate the quantity of pure ammo- nia in the alum. A variety of alum, contain- ing both potash and ammonia, may also be found. This will occur where urine has been used, as well as muriate of potash, in its fabri- cation. If any of these sulphates of alu- mina and potash be acted on in a watery solu- tion, by a gelatinous alumina, a neutral triple salt is formed, which precipitates in a nearly insoluble state. When alum in powder is mixed with flour or sugar, and calcined, it forms the pyropho- rus of Homberg. Mr. Winter first mentioned, that another variety of alum can be made with soda, in- stead of potash. This salt, which crystallizes in octahedrons, has been also made with pure muriate of soda, and bisulphate of alumina, at the laboratory of Hurlett, by Mr. W. Wil- son. It is extremely difficult to form, and ef- floresces like the sulphate of soda. On the subject of soda-alum, I published a short paper in the Journal of Science for July 1822. The form and taste of this salt are exactly the same as those of common alum ; but it is less hard, being easily crushed between the fingers, to which it imparts an appearance of moisture. Its specific gravity is 1.6. 100 parts of water at 60 F. dissolve 110 of it; forming a solution, whose sp. gravity is 1.296. In this respect, potash-alum is very different. ALU ISO AMB For 100 parts of water dissolve only from 8 to y parts, forming a saturated solution, whose sp. gr. is no more than 1.0465. Its consti- tuents are by my analysis, Sulphuric acid, 34.00 4 primes, 33.96 Alumina, Soda, Water, 10.75 6.48 49.00 100.5 3 I 25 10.82 6.79 48.43 100.00 helps the separation of its butter. If added in a very small quantity to turbid water, in a few minutes it renders it perfectly lim- pid, without any bad taste or quality ; while the sulphuric acid imparts to it a very sensible acidity, and does not precipitate so soon, or so well, the opaque earthy mixtures that render it turbid, as I have often tried. It is used in making pyrophorus, in tanning, and many other manufactories, particularly in the art of Or it consists of 3 primes sulphate of alumina dyeing, in which it is of the greatest and most 1 sulphate of soda. To each of the former, 5 primes of water may be assigned, and to the latter 10, as in Glauber's salt. The only injurious contamination of alum is sulphate of iron. It is detected by ferro- prussiate of potash. To get rid of it cheaply, JV1. Thenard recommended dissolving the alum in boiling water, and agitating the solution with rods as it cools. The salt is thus reduced to a fine granular powder, which being washed two or three times with cold water, and drained, yields a perfectly pure alum. For a very ad- vantageous mode of concentrating alum li- quors, as well as those of other salts, on the great scale, see EVAPORATION". Mr. Phillips describes in the 4th volume of the Annals of Philosophy, N. S. a new sul- phate of alumina, which he obtained by put- ting moist alumina into dilute sulphuric acid, and adding more occasionally, until it remained in excess ; being now filtered, a clear dense solution was obtained, which, when dropped into water, instantly let fall a precipitate, al- most as abundant as that from muriate of an- timony. It also began to precipitate imme- diately, even of itself, though no tendency of this kind was observed, as long as the excess of alumina remained mixed with it. The de- important use, by cleansing and opening the pores on the surface of the substance to be dyed, rendering it fit for receiving the colour- ing particles, (by which the alum is generally decomposed), and at the same time making the colour fixed. Crayons generally consist of the earth of alum, finely powdered, and tinged for the purpose. In medicine it is employed as an astringent. ALUMINITE. A mineral of a snow- white colour, dull, opaque, and having a fine earthy fracture. It has a glistening streak. It is found in kidney-shaped pieces, which are soft to the touch, and adhere slightly to the tongue. Sp. gravity, 1.67. It consists of sulphuric acid, 1 9.25 Alumina, 32.50 Water, 47-00 Silica, lime, and oxide of iron, 1.25 100.00 The above alum ore is found chiefly in the alluvial strata round Halle in Saxony. AMADOU. It is a variety of the loletus igniarius, found on old ash and other trees. It is boiled in water to extract its soluble parts, then dried and beat with a mallet to loosen its texture. It has now the appear- position went on for several months ; but the ance of very spongy doe-skin leather. It is clear part was always precipitable by water Another property of this sulphate of alumina, is that if heated to 160 or 170 Fahr. it be- lastly impregnated with a solution of nitre, and dried, when it is called spunk, or German tinder ; a substance much used on the conti- comes opaque and thick ; but upon cooling, in nent for lighting fires, either from the collision / i ., i _ _i . TtT "nun -^.fl'-A. J _i.__i *. xV. * n **AA^-v\ stswirl^itc-o a few days'it becomes clear again. Mr. Phil- of flint and steel, or from the sudden condensa- lips considers the number 27 as representing tion of air in the atmospheric pyrophorus. AMALGAM. This name is applied to the combinations of mercury with other me- tallic substances. See MERCURY. AMBER is a hard, brittle, tasteless sub- stance, sometimes perfectly transparent, but the atom of alumina to hydrogen = 1 ; and the above salt as consisting of 2 atoms sul- phuric acid = 40 X 2 rr 80 + 3 atoms alu- mina = 27 X 3 81 ; or on the oxygen scale of 2 X 5 = 10 acid + 3.375 X 3 =: 10. 125 alumina. Alum is used in large quantities in many mostly semitransparent or opaque, and of a glossy surface : it is found of all colours, but manufactories. When added to tallow, it ren- chiefly yellow or orange, and often contains ders it harder. Printers* cushions, and the blocks used in the calico manufactory, are rubbed with burned alum to remove any greasi- ness, which might prevent the ink or colour from sticking. Wood sufficiently soaked in a solution of alum does not easily take fire ; and the same is true of paper impregnated with it, which is fitter to keep gunpowder, as it also excludes moisture. Paper impregnated with leaves or insects ; its specific gravity is from 1.065 to 1.100; its fracture is even, smooth, and glossy ; it is capable of a fine polish, and becomes electric by friction ; when rubbed or heated, it gives a peculiar agreeable smell, particularly when it melts, that is at 550 of Fahrenheit, but it then loses its transparency ; projected on burning coals, it burns with a whitish flame, and a whitish-yellow smoke, alum is useful in whitening silver, and silver- but gives very little soot, and leaves brownish ing brass without heat. Alum mixed in milk ashes ; it is insoluble in water and alcohol, AMB 140 AMB though the latter, when highly rectified, ex- tracts a reddish colour from it ; but it is solu- ble in the sulphuric acid, which then acquires a reddish-purple colour, and is precipitable from it by water. No other acid dissolves it, nor is it soluble in essential or expressed oils, without some decomposition and long diges- tion ; but pure alkali dissolves it. By distil- lation it affords a small quantity of water, with a little acetic acid, an oil, and a peculiar acid. See ACID (SucciNic). The oil rises at first colourless ; but, as the heat increases, becomes brown, thick, and empyreumatic. The oil may be rectified by successive distil- lations, or it may be obtained very light and limpid at once, if it be put into a glass alem- bic with water, as the elder Rouelle directs, and distilled at a heat not greater than 212 Fahr. It requires to be kept in stone bottles, however, to retain this state ; for in glass ves- sels it becomes brown by the action of light Amber is met with plentifully in regular mines in some parts of Prussia. The upper surface is composed of sand, under which is a stratum of loam, and under this a bed of wood, partly entire, but chiefly mouldered or changed into a bituminous snbstance. Under the wood is a stratum of sulphuric or rather aluminous mineral, in which the amber is found. Strong sulphurous exhalations are often perceived in the pits. Detached pieces are also found occasionally on the sea-coast in various countries. It has been found in gravel beds near London. In the Royal Cabinet at Berlin there is a mass of 1 8 Ibs. weight, supposed to be the largest ever found. Jussieu asserts, that the delicate in- sects in amber, which prove the tranquillity of its formation, are not European. M. Hauy has pointed out the following distinctions be- tween mellite and copal, the bodies which most closely resemble amber. Mellite is infusible by heat. A bit of copal heated at the end of a knife takes fire, melting into drops, which flatten as they fall ; whereas amber burns with spitting and frothing ; and when its liquefied particles drop, they rebound from the plane which receives them. The origin of amber is at present involved in perfect obscurity, though the rapid progress of vegetable chemistry pro- mises soon to throw light on it. Various frauds are practised with this substance. Neu- mann states as the common practices of work- men the two following : The one consists in surrounding the amber with sand in an iron pot, and cementing it with a gradual fire for forty hours, some small pieces placed near the sides of the vessel being occasionally taken out for judging of the effect of the operation : the second method, which he says is that most generally practised, is by digesting and boil- ing the amber about twenty hours with rape- seed oil, by which it is rendered both clear and hard. Werner has divided it into two sub-species, the white and the yellow ; but there is little advantage in the distinction. Its ultimate con- stituents are carbon, hydrogen, and oxygen. Although my experiments on the ultimate analysis of amber were conducted carefully with re-trituration and re-ignition, no good atomic configuration of it occurred to me. It yielded in 100 parts, 70. G8 carbon, 11. C2 hy- drogen, and 17'77 oxygen; or of the elements of water 20 + hydrogen in excess 9.4, inde- pendently of the carbon. Phil Trans. 1822. In the second volume of the Edinburgh Philosophical Journal, Dr. Brewster has given an account of some optical properties of am- ber, from which he considers it established beyond a doubt that amber is an indurated ve- getable juice; and that the traces of a regular structure, indicated by its action upon pola- rized light, are not the effect of the ordinary laws of crystallization by which mellite has been formed, but are produced by the same causes which influence the mechanical condi- tion of gum arabic, and other gums, which are known to be formed by the successive de- position and induration of vegetable fluids. Amber is also used in varnishes. See VARNISH and OIL of AMBER. AMBERGRIS is found in the sea, near the coasts of various tropical countries ; and has also been taken out of the intestines of the physeter macrocephalus, the spermaceti whale. As it has not been found in any whales but such as are dead or sick, its production is generally supposed to be owing to disease, though some have a little too peremptorily affirmed it to be the cause of the morbid affec- tion. As no large piece has ever been found without a greater or less quantity of the beaks of the sepia octopodia, the common food of the spermaceti whale, interspersed throughout its substance, there can be little doubt of its ori- ginating in the intestines of the whale ; for if it were occasionally swallowed by it only, and then caused disease, it must much more fre- quently be found without these, when it is met with floating in the sea, or thrown upon the shore. Ambergris is found of various sizes, gene- rally in small fragments, but sometimes so large as to weigh near two hundred pounds. When taken from the whale it is not so hard as it becomes afterward on exposure to the air. Its specific gravity ranges from 780 to 926. If good, it adheres like wax to the edge of a knife with which it is scraped, retains the impression of the teeth or nails, and emits a fat odoriferous liquid on being penetrated with a hot needle. It is generally brittle ; but, on rubbing it with the nail, it becomes smooth like hard soap. Its colour is either white, black, ash-coloured, yellow, or blackish; or it is variegated, namely, grey with black specks, or grey with yellow specks. Its smell is peculiar, and not easy to be counterfeited. At 144 it melts, and at 212 is volatilized in AME 141 AMM the form of a white vapour. But, on a red- hot coal, it burns, and is entirely dissipated. Water has no action on it; acids, except nitric, act feebly on it ; alkalis combine with it, and form a soap ; ether and the volatile oils dissolve it ; so do the fixed oils, and also ammonia,-when assisted by heat ; alcohol dis- solves a portion of it, and is of great use in analyzing it, by separating its constituent parts. According to Bouillon la Grange, who has given the latest analyses of it, 3820 parts of ambergris consist of adipocere 2016 parts, a resinous substance 11 67, benzoic acid 425, and coal 212. But Bucholz could find no benzoic acid in it. I examined two different specimens with considerable attention. The one yielded benzoic acid, the other, equally genuine to all appearance, afforded none. See ADIPOCERE and INTESTINAL CONCRE- TION. An alcoholic solution of ambergris, added in minute quantity to lavender water, tooth powder, hair powder, wash balls, &c. com- municates its peculiar fragrance. Its retail price being in London so high as a guinea per oz. leads to many adulterations. These con- sist of various mixtures of benzoin, labdanum, meal, &c. scented with musk. The greasy appearance and smell which heated ambergris exhibits, afford good criteria* joined to its solubility in hot ether and alcohol. It has occasionally been employed in me- dicine, but its use is now confined to the perfumer. Dr. Swediaur took thirty grains of it without perceiving any sensible effect. AMBLYGONITE. A greenish- coloured mineral of different pale shades, marked on the surface with reddish and yellowish-brown spots. It occurs massive and crystallized in oblique four-sided prisms. Lustre vitreous ; cleavage parallel with the sides of an oblique four-sided prism of 106 10' and 77 50'; fracture uneven ; fragments rhomboidal ; trans- lucent ; hardness, as felspar ; brittle ; sp. gr. 3.0. Intumesces with the blowpipe, and fuses with a reddish-yellow phosphorescence into a white enamel. It occurs in granite, along with green topaz and tourmaline, near Pinig in Saxony. It seems to be a species of spodumene. AMBREINE. By digesting ambergris in hot alcohol, sp. gr. 0.827, the peculiar sub- stance called ambreine by Pelletier and Ca- venton is obtained. The alcohol, on cooling, deposits the ambreine in very bulky and irregular crystals, which still retain a very considerable portion of alcohol. Thus ob- tained, it has the following properties : It is of a brilliant white colour, has an agreeable odour, of which it is deprived by repeated solutions and crystallizations. It is destitute of taste, and does not act on vegetable blues. It is insoluble in water, but dissolves readily in alcohol and ether ; and in much greater quantity in these liquids, when hot, than when cold. It melts at the temperature of 86, softening at 77<>. It is partly volatilized and decomposed into a white smoke when heated above 212. It does not seem capable of combining with an alkali, or of being saponi- fied. When heated with nitric acid, it becomes green and then yellow, while nitrous gas is exhaled. By this absorption of oxygen, it is converted into an acid, which has been called ambreic acid. This acid is yellowish white, has a peculiar smell, reddens vegetable blues, does not melt at 212, and evolves no ammonia when decomposed at higher temperatures. It is soluble in alcohol and ether ; but slightly so in water. Ambreate of potash gives yellow precipitates with muriate of lime, muriate of barytes, sulphate of copper, sulphate of iron, nitrate of silver, acetate of lead, corrosive sublimate, muriate of tin, and muriate of gold. Journ. de Pharm. v. 49. AMETHYST. The amethyst is a gem of a violet colour, and great brilliancy, said to be as hard as the ruby or sapphire, from which it only differs in colour. This is called the oriental amethyst, and is very rare. When it inclines to the purple or rosy colour, it is more esteemed than when it is nearer to the blue. These amethysts have the same figure, hardness, specific gravity, and other qualities, as the best sapphires or rubies, and come from the same places, particularly from Persia, Arabia, Armenia, and the West Indies. The occidental amethysts are merely coloured crys- tasl or quartz. See QUARTZ and SAPPHIRE. AMIANTHOIDE. A mineral, in long capillary filaments, of an olive green colour, flexible and elastic. Lustre, brilliant silky. It is composed of silica 47 ; lime 11 ; mag- nesia 7 ; oxide of iron 20 ; manganese 10. Vauquelln. It is found at Oisans in France. Phillips' s Mineralogy. AMIANTHUS, mountain flax. See ASBESTUS. AMIATITE. FIORITE, or PEARL- SINTER. AMIDINE. This is a substance produced, according to M. de Saussure, when we aban- don the paste of starch to itself, at the ordinary temperature, with or without the contact of air. See STARCH. AMMONIA, called also volatile alkali. We shall first consider this substance in its purely scientific relations, and then detail its manufacture on the great scale, and its uses in the arts. There is a saline body, formerly brought from Egypt, where it was separated from soot by sublimation, but which is now made abundantly in Europe, called sal am- moniac. From this salt pure ammonia can be readily obtained by the following process : Mix unslaked quicklime with its own weight of sal ammoniac, each in fine powder, and introduce them into a glass retort. Join to the beak of the retort, by a collar of caoutchouc, fa neck of an India rubber bottle answers AMM 142 AMM Well), a glass tube about 18 inches long, con- taining pieces of ignited muriate of lime. This tube should lie in a horizontal position, and its free end, previously bent obliquely by the blowpipe, should dip into dry mercury in a pneumatic trough. A slip of porous paper, as an additional precaution, may be tied round the tube, and kept moist with ether. If a gentle heat from a charcoal chauffer or lamp be now applied to the bottom of the retort, a gaseous body will bubble up through the mercury. Fill a little glass tube, sealed at one end, with the gas, and transfer it, closely stopped at the other end, into a basin contain- ing water. If the water rise instantly and fill the whole tube, the gas is pure, and may be received for examination. Ammonia is a transparent, colourless, and consequently invisible gas, possessed of elas- ticity, and the other mechanical properties of the atmospherical air. Its specific gravity is an important datum in chemical researches, and has been rather differently stated. Yet, as no aeriform body is more easily obtained in a pure state than ammonia, this diversity among accurate experimentalists, shows the nicety of this statical operation. MM. Biot and Arago make it rr 0.59669 by experiment, and by calculation from its elementary gases, they make it = 0.59438. Kirwan says, that 100 cubic inches weigh 18.16 gr. at 30 inches of bar. and 61 F. which compared to air reckoned 30.519, gives 0.59540. Sir H. Davy determines its density to be m 0.590, with which estimate the theoretic calculations of Dr. Prout, in the 6th volume of the Annals of Philosophy, agree. This gas has an exceedingly pungent smell, well known by the old name of spirits of hartshorn. An animal plunged into it speedily dies. It extinguishes combustion, but being itself to a certain degree combustible, the flame of a taper immersed in it, is enlarged before going out. By exposing this gas to a very low temperature M. Bussy succeeded in liquifying it. See ACID (SULPHUROUS). It has a very acrid taste. Water condenses it very rapidly. The following valuable table of its aqueous combinations has been given by Sir H. Davy. Sp. Gr. 0.8750 0-8875 0.9000 0.9054 0.9166 0.9255 0.9326 0.9385 0.9435 0.9476 0.9513 0.9545 0.9573 0.9597 0.9619 0.9692 Water is capable of dissolving easily about one- third of its weight of ammoniacal gas, or 460 times its bulk. Hence, when placed in contact with a tube filled with this gas, water rushes into it with explosive velocity. Pro- bably the quantity of ammonia stated in the above table is too high by about one per cent. The following table of the quantity of am- monia in 100 parts, by weight, of its aqueous combinations at successive densities, was pub- lished by me in the Philosophical Magazine for March 1821. Ammonia. Water. 32.50 67.50 29.25 70.75 26.00 74.00 25.37 74.63 22.07 77-93 19.54 80.46 17-52 82.48 15.88 84.12 14.53 85.47 13.46 86.54 12.40 87.60 11.56 88.44 10.82 89.18 10.17 89.83 9.60 90.40 9.50 90.50 Water of 0.900. Ammo- nia in 100. Water in 100. Sp. gr. by expe- riment. Mean specific gravity. Equivalent primes. 100 26.500 73.500 0.9000 95 25.175 74.825 0.9045 0.90452 wat. amm. 90 23.850 76.150 0.9090 0.90909 24 + 76, 6 to 1 85 22.525 77.475 0.9133 0.91370 80 21.200 78.800 0.917710.91838 21.25 + 78.75, 7 to 1 75 19.875 80.125 0.9227 0.92308 70 18.550 81.450 0.9275 0.92780 19.1+80.9, 8tol 65 17.225 82.775. 0.9320 0.93264 17.35 + 82.65, 9 to 1 60 15.900 84.100 0.936310.93750 15.9+84.1 lOtol 55 14.575 85.425 0.9410 0.94241 14.66+85.34, 11 to 1 50 13.250 86.750 0.9455 0.94737 13.60 + 86.40, 12 to 1 45 11.925 88.075 0.9510 0.95238 11.9+88.1, 14tol 40 10.600 89.400 0.9564 0.95744 11.2 + 88.8, 15tol 35 9.275 90-725 0.9614 0.96256 30 7-950 92-050 0.966210.96774 8.63+91.37, 20tol 25 6.625 93.375 0.9716 0.97297 7 + 93, 25 to 1 20 5.300 94.700 0.9768 0.97826 6 + 94, 30 to 1 15 3.975 196.025 0.9828 10.98360 4.5+95.5 40tol 10 2.650 197-350 0.98870.9890 3+97, CJOtol 5 1.325 198.675 0.994510.99447 AMM 143 AMM The remarkable expanslveness which am- monia carries into its first condensation with water, continues in the subsequent dilutions of its aqueous combinations. This curious property is not peculiar to pure ammon;r,, but belongs, as I have found, to some of its salts. Thus sal ammoniac, by its union with water, causes an enlargement of the total volume of the compound, beyond the volume of the con- stituents of the solution. Or the specific gra- vity of the saturated solution is less than the mean sp. gravity of the salt and water. I know of no salts with which this phenomenon occurs, except the ammoniacal. Near the two extremities of the table, the experimental and computed specific gravities agree; the reciprocal affinity thus balancing the peculiar expansiveness communicated by the ammonia, which becomes conspicuous in the intermediate proportions of water and gas. This fact is in unison with the general laws of chemical combination. Since 73.5 grains of distilled water exist in 1 00 water of ammonia, specific gravity 0.900, which occupy the volume of 1.111, one part of water in bulk will be converted into almost exactly one and a half of such water of am- monia. 100 grains of this water contain 147-2 cubic inches of gas. Hence 1 grain of water holds condensed in such aqueous ammonia 2 cubic inches of the gas, or one volume of dis- tilled water is united to 505 volumes of gas. It is a remarkable coincidence, that one volume of water, when converted into aqueous muriatic acid, specific gravity 1.200, or into aqueous ammonia, sp. grav. 0.900, expands in either case into a volume and a half. If from 998 we deduct the specific gravity of water of ammonia, expressed in three in- tegers, the remainder, divided by 4, will give a quotient representing the quantity of real alkali present. This rule is exact for all such liquid ammonia as is commonly used in che- mical researches and in medicine, viz. be- tween sp. gravities 930 and 980, water being 1000. Liquid ammonia, as the aqueous compound is termed, may therefore like spirits be very accurately valued by its specific gravity. But it differs remarkably from alcoholic mixtures in this respect, that the strongest ammoniacal liquor, when it is diluted with water, suffers little condensation of volume. The specific gravity of the dilute, is not far from that of its components. Hence having one point accu- rately, we can compute all below it, by paying attention to the rule given under SPECIFIC GRAVITY. To procure aqueous ammonia, we may use either a common still and refri- geratory or a Woolfe's apparatus. The latter should be preferred. Into a retort we put a mixture of two parts of slaked lime, and one part of pulverized sal ammoniac, and having connected the beak of the retort with the Woolfe's apparatus, containing pure water, we then disengage the ammonia, by the appli- cation of heat. When gas ceases to be evolved, the addition of a little hot water will renew its disengagement, and ensure complete decom r position of the salt. Since sal ammoniac con- tains nearly % its weight of ammonia, ten pounds of it should yield by economical treat- ment 30 pounds of liquid, whose specific gra- vity is 0.950, which is as strong as the ordi- nary purposes of chemistry and medicine re- quire ; and it will form twice that quantity, or 60 pounds of the common water of ammonia sold by apothecaries, which has rarely a smaller density than 0.978 or 0.980. There is no temptation to make it with the ammoniacal carbonate ; but if this salt be accidentally pre- sent, it is instantly detected by its causing a milkiness hi lime water. Ammoniacal gas, perfectly dry when mixed with oxygen, explodes with the electric spark, and is converted into water and nitrogen, as has been shown in an ingenious paper by Dr. Henry. But the simplest, and perhaps most accurate mode of resolving ammonia into its elementary constituents, is that first practised by M. Berthollet, the celebrated discoverer of its composition. This consists in making the pure gas traverse very slowly an ignited por- celain tube of a small diameter. The process, as lately repeated by M. Gay Lussac, yielded from 100 cubic inches of ammonia, 200 cubic inches of constituent gases ; of which, by sub- sequent analysis, 50 were found to be nitro- gen, and 1 50 hydrogen. Hence we see, that the reciprocal affinity of the ammoniacal ele- ments had effected a condensation equal to one- half of the volume of the free gases. It ap- pears by the most recent determinations, that the specific gravity of hydrogen is 0.0694, compared to air as unity, and that of nitro- gen 0.9722. Three volumes of the former will therefore weigh 0.2082, and one of the latter, 0.9722 ; the sum of which numbers, 1.1804, divided by 2, ought to coincide with the experimental density of ammonia. Now, it is 0.5902, being an exact correspondence. And the ratio of the two weights, reduced to 100 parts, will be 82.36 nitrogen to 17-64 hydrogen. To reduce ammonia to the system of equivalents, or to find its saturating ratio on that scale where oxygen represents unity, we have this proportion ; 9722 : 1.75 : : 1.1804 : 2.125; so that 2.125 may be called its prime equivalent. We shall find this num- ber deduced from analysis, confirmed by the synthesis of all the ammoniacal salts. Dr. Prout, in an able memoir on the rela- tion between the specific gravities of gaseous bodies, and the weights of their atoms, pub- lished in the 6th vol. of the Annals of Philo- sophy, makes the theoretical weight of the atom of ammonia to be only 1.9375, considering it as a compound of 1 atom of azote, and l atoms of hydrogen. This statement appears to be a logical inference from Mr. Dalton's AMM 144 AMM hypotliesis of atomical combination. For water, the great groundwork of his atomic structure, is represented as a compound of one atom of oxygen with one atom of hydro- gen ; and this atomical unit of hydrogen con- sists of two volumes of the gas. Hence three volumes of the gas must represent an atom and a half. But an atom is, by its very de- finition, indivisible. Dr. Prout, in the 38th number of the Annals, restores the true pro- portions of 3 atoms hydrogen + 1 azote. Our doctrine of equivalent primes, resting on the basis of experimental induction, claims no knowledge of the atomical constitution of bodies. The alkaline nature of ammonia is demon- strated, not only by its neutralizing acidity, and changing the vegetable reds to purple or green, but also by its being attracted to the negative pole of a voltaic arrangement. When a pretty strong electric power is applied to am- monia in its liquid or solid combinations, sim- ple decomposition is effected ; but in contact with mercury, very mysterious phenomena oc- cur. If a globule of mercury be surrounded with a little water of ammonia, or placed in a little cavity in a piece of sal ammoniac, and then subjected to the voltaic power by two wires, the negative touching the mercury, and the positive the ammoniacal compound, the globule is instantly covered with a circulating him, a white smoke rises from it, and its volume enlarges, whilst it shoots out ramifica- tions of a semi-solid consistence over the salt. The amalgam has the consistence of soft but- ter, and may be cut with a knife. Whenever the electrization is suspended, the crab-like fibres retract towards the central mass, which soon, by the constant formation of white saline films, resumes its pristine globular shape and size. The enlargement of volume seems to amount occasionally to ten times that of the mercury, when a small globule is employed. Sir H. Davy, Berzelius, and MM. Gay Lus- sac, and Thenard, have studied this singular phenomenon with great care. They produced the very same substance by putting an amal- gam of mercury and potassium into the moist- ened cupel of sal ammoniac. It becomes five or six times larger, assumes the consistence of butter, whilst it retains its metallic lustre. What takes place in these experiments ? In the second case, the substance of metallic aspect which we obtain is an ammoniacal hydruret of mercury and potassium. There is formed, besides, muriate of potash. Consequently a portion of the potassium of the amalgam de- composes the water, becomes potash, which itself decomposes the muriate of ammonia. Thence result hydrogen and ammonia, which, in the nascent state, unite to the undecomposed amalgam. In the first experiment, the sub- stance which, as in the second, presents the metallic aspect, is only an ammoniacal hy- druret of mercury ; its formation is accompa- nied by the perceptible evolution of a certain quantity of chlorine at the positive pole. It is obvious, therefore, that the salt is decom- posed by the electricity. The hydrogen of the iriuriatic acid, and the Ammonia, both combine with the mercury. These hydrurets possess the following properties : Their sp. gravity is in general below 3.0 ; exposed for some time to the temperature of 32 F. they assume considerable hardness, and crystallize in cubes, which are often as beautiful and large as those of bismuth. Ether and alcohol instantly destroy these amalgams, exciting a brisk effervescence with them, and reproducing the pure mercurial globule. These amalgams are slightly per- manent in the air, if undisturbed ; but the least agitation is fatal to their existence. MM. Gay Lussac and Thenard found, by immer- sion in water, that mercury, in passing to the state of a hydruret, absorbed 3 times its volume of hydrogen. The ammoniacal hy- druret of mercury and potassium may exist by itself; but as soon as we attempt to sepa- rate or oxidize the potassium, its other consti- tuent principles also separate. Hence this hydruret is speedily decomposed by the air, by oxygen gas, and in general by all bodies that act upon potassium. It is even affected by mercury, so that in treating it with this metal, we may easily determine the iclative quantity of ammonia and hydrogen which it contains. We need only for this purpose take up the interior parts of the hydruret with a little iron spoon, fill up with it a little glass tube, already nearly full of mercury ; and closing this with a very dry stopper, invert it in mercury equally dry. The hydruret will rise to the upper part of the tube, will be de- composed, especially by a slight agitation, and will give out hydrogen and ammonia in the ratio of 1 to 2.5. The mere ammoniacal hydrurets contain but a very small quantity of hydrogen and ammonia. By supposing that, in the ammo- niacal hydruret of mercury, the hydrogen is to the ammonia in the same proportion as in the ammoniacal hydruret of mercury and pot- assium, it will appear that the first is formed, in volume, of 1 of mercury, 3.47 hydrogen, and 8-67 ammoniacal gas, at the mean pres- sure and temperature of 30. and 60 ; or in freight, of about 1800 parts of mercury, with 1 part of hydrogen, and 1 of ammonia. Ammonia is not affected by a cherry-red heat. According to Guyton de Morveau, it becomes a liquid at about 40 0, or at the freezing point of mercury ; but it is un- certain whether the appearances he observed may not have been owing to hygrometric water, as happens with chlorine gas. The ammoniacal liquid loses its pungent smell as its temperature sinks, till at 50 it gelati- nizes, if suddenly coole:l ; but if slowly cooled, it crystallizes. AMM AMM Oxygen, by means of electricity, or a mere red heat, resolves ammonia into water and nitrogen. When there is a considerable ex- cess of oxygen, it acidifies a portion of the nitrogen into nitrous acid, whence many falla- cies in analysis have arisen. Chlorine and ammonia exercise so powerful an action on each other, that when mixed suddenly, a sheet of white flame pervades them. The simplest way of making this fine experiment, is to in- vert a matrass, with a wide mouth and conical neck, over another with a taper neck, contain- ing a mixture of sal ammoniac and lime, heated by a lamp. As soon as the upper ves- sel seems to be full of ammonia, by the over- flow of the pungent gas, it is to be cautiously lifted up, and inserted, in a perpendicular di- rection, into a wide-mouthed glass decanter or flask, filled with chlorine. On seizing the two vessels thus joined with the two hands covered with gloves, and suddenly inverting them, like a sand-glass, the- heavy chlorine and light ammonia, rushing in opposite directions, unite with the evolution of flame. As one volume of ammonia contains, in a condensed state, one and a half of hydrogen, which requires for its saturation just one and a half of chlo- rine, this quantity should resolve the mixture into muriatic acid and nitrogen, and thereby give a ready analysis of the alkaline gas. If the proportion of chlorine be less, sal ammo- niac and nitrogen are the results. The same thing happens on mixing the aqueous solu- tions of ammonia and chlorine. But if large bubbles of chlorine be let up in ammoniacal water of moderate strength, luminous streaks are seen in the dark to pervade the liquid, and the same reciprocal change of the ingre- dients is effected. MM. Gay Lussac and Thenard state that when three parts of ammoniacal gas and one of chlorine are mixed together, they condense into sal ammoniac, and azote equal to l-10tli the whole volume is given out. This result is at variance with their own theory of volumes. Three of ammoniacal gas consist of 4 hy- drogen, and 1^ nitrogen in a condensed state; 1 of chlorine seizes 1 of hydrogen, to form 2 of muriatic acid gas, which precipitate with 2 of ammonia, in a pulverulent muriate. But the third volume of ammonia had parted with 1 volume of its hydrogen to the chlorine, and another half-volume of hydrogen will unite with 0.166 of a volume of nitrogen, to form /\ f*f* 0.33 of redundant ammonia, while 0.33 of a volume of nitrogen is left unemployed. Hence 2-3ds of a volume, or 1-Cth of the ori- ginal bulk of the mixed gases, ought to remain ; consisting of equal parts of ammonia and ni- trogen, instead of 1-1 Oth of azote, as the French chemists state. Iodine has an analogous action on ammo- nia ; seizing a portion of its hydrogen to form hydriodic acid, whence hydriodate of ammonia results ; while another portion of iodine unites with the liberated nitrogen, to form the explo- sive pulverulent iodide. Cyanogen and ammoniacal gas begin to act upon each other whenever they come into con- tact, but some hours are requisite to render the effect complete. They unite in the proportion nearly of 1 to l, forming a compound which gives a dark orange brown colour to water, but dissolves in only a very small quantity of water. The solution does not produce prussian blue with the salts of iron. By transmitting ammoniacal gas through charcoal ignited in a tube, prussic or hydro- cyanic acid is formed. The action of the alkaline metals on gase- ous ammonia is very curious. When potas- sium is fused in that gas, a very fusible olive- green substance, consisting of potassium, nitrogen, and ammonia, is formed ; and a volume of hydrogen remains, exactly equal to what would result from the action on water of the quantity of potassium employed. Hence, according to M. Thenard, the ammonia is divided into two portions. One is decomposed, so that its nitrogen combines with the potas- sium, and its hydrogen remains free, whilst the other is absorbed in whole or in part by the nitroguret of potassium. Sodium acts in the same manner. The olive substance is opaque, and it is only when in plates of ex- treme thinness that it appears semitransparent ; it has nothing of the metallic appearance ; it is heavier than water ; and on minute inspec- tion seems imperfectly crystallized. When it is exposed to a heat progressively increased, it melts, disengages ammonia, and hydrogen, and nitrogen, in the proportions constituting ammonia ; then it becomes solid, still pre- serving its green colour, and is converted into a nitroguret of potassium or sodium. Exposed to the air at the ordinary temperature, it attracts only its humidity, but not its oxygen, and is slowly transformed into ammoniacal gas, and potash or soda. It burns vividly when projected into a hot crucible, or when heated in a vessel containing oxygen. Water and acids produce also sudden decomposition, with the extrication of heat. Alkalis or alka- line salts are produced. Alcohol likewise de- composes it with similar results. The pre- ceding description of the compound of ammonia with potassium, as prepared by MM. Gay Lussac and Thenard, was controverted by Sir H. Davy. The experiments of this accurate chemist led to the conclusion, that the presence of moisture had modified their results. In pro- portion as more precautions are taken to keep every thing absolutely dry, so in proportion is less ammonia regenerated. He seldom obtained as much as l-10th of the quantity absorbed; AMM 146 AMM and he never could procure hydrogen and ni- trogen in the proportions constituting ammo- nia; there was always an excess of nitrogen. The following experiment was conducted with the utmost nicety. 3| gr. of potassium were heated in 12 cubic inches of ammoniacal gas ; 75 were absorbed, and 3.2 of hydrogen evolved. On distilling the olive-coloured solid in a tube of platina, 9 cubical inches of gas were given off, and half a cubical inch remained in the tube and adapters. Of the 9 cubical inches, one-fifth of a cubical inch only was ammonia ; 10 measures of the permanent gas mixed with 7-5 of oxygen, and acted upon by the electri- cal spark, left a residuum of 7-5. He infers that the results of the analysis of ammonia, by electricity and potassium, are the same. On the whole we may legitimately infer, that there is something yet unexplained in these phenomena. The potassium separates from ammonia as much hydrogen as an equal weight of it would from water. If two volumes of hydrogen be thus detached from the alka- line gas, the remaining volume, with the volume of nitrogen, will be left to combine with the potassium, forming a triple compound, somewhat analogous to the cyanides, a com- pound capable of condensing ammonia. For an account of a singular combination of am- monia, by which its volatility seems destroyed, see CHLORINE, When ammoniacal gas is transmitted over ignited wires of iron, copper, platina, &c. it is decomposed completely, and though the me- tals are not increased in weight, they have be- come extremely brittle. Iron, at the same temperature, decomposes the ammonia, with double the rapidity that platinum does. At a high temperature, the protoxide of nitrogen decomposes ammonia. Of the ordinary metals, zinc is the only one which liquid ammonia oxidizes and then dissolves. But it acts on many of the metallic oxides. At a high temperature the gas deoxi- dizes all those which are reducible by hydrogen. The oxides soluble in liquid ammonia are, the oxide of zinc, the protoxide and peroxide of copper, the oxide of silver, the third and fourth oxides of antimony, the oxide of tellurium, the protoxides of nickel, cobalt, and iron, the peroxide of tin, mercury, gold, and platinum. The first five are very soluble, the rest less so. These combinations can be obtained by eva- poration, in the dry state, only with copper, antimony, mercury, gold, platinum, and sil- ver ; the four last of which are very remarkable for their detonating property. See the parti- cular metals. All the acids are susceptible of combining wit^h ammonia, and they almost all form with it rteutral compounds. M. Gay Lussac made the important discovery, that whenever the acid is gaseous, its combination with ammo. niacal gas takes place in a simple ratio of de- terminate volumes, whether a neutral or a subsalt be formed. AMMONIACAL SALTS have the fol- lowing general characters 1st, When treated with a caustic fixed al- kali or earth, they exhale the peculiar smell of ammonia. 2d, They are generally soluble in water, and crystallizable. 3d, They are all decomposed at a moderate red heat ; and if the acid be fixed, as the phos- phoric or boracic, the ammonia comes away pure. 4/i, When they are dropped into a solu- tion of muriate of platina, a yellow precipitate falls. 1. Acetate. This saline compound was formerly called the spirit of Mindererus, who introduced it into medicine as a febrifuge sudorific. By saturating a pretty strong acetic acid with subcarbonate of ammonia, enclosing the liquid under the receiver of an air-pump, along with a saucerful of sulphuric acid, and exhausting the air, the salt will concrete in acicular crystals, which are nearly neutral. It may also be made very conveniently, by mixing hot saturated solutions of acetate of lead, and sulphate of ammonia, taking 100 of the first salt in its ordinary state to 34.4 of the second, well dried at a heat of 212. Or even muriate of ammonia will answer in the proportion of 27.9 to 100 of the acetate. Acetate of ammo- nia has a cooling sweetish taste. It is delique- scent, and volatile at all temperatures ; but it sublimes in the solid state at 250. It consists of 75f of dry acetic acid, and 24 ammonia. When intended for medicine, it should always be prepared from pure acetic acid, and subcar- bonate of ammonia. Arseniate of ammonia may be formed by saturating the arsenic acid with ammonia, and evaporating the liquid. Crystals of a rhomboidal prismatic form are obtained. A binarseniate may also be made by using an ex- cess of acid. At a red heat, the ammonia of both salts is decomposed, and the acid is reduced to the metallic state. Under the respective acids, an account of several ammoniacal salts will be found. As the muriate, however, con- stitutes an extensive manufacture, we shall enter here into some additional details con- cerning its production. Sal ammoniac was originally fabricated in Egypt. The dung of camels and other animals constitutes the chief fuel used in that country. The soot is carefully collected. Globular glass vessels, about a foot in diameter, are rilled within a few inches of their mouth with it, and are then arranged in an oblong furnace, where they are exposed to a heat gradually increased. The upper part of the glass bal- loon stands out of the furnace, and is kept relatively cool by the air. On the 3d day the operation is completed, at which time they AMM 147 AMY plunge an iron rod occasionally into the mouths of the globes, to prevent them from closing up, and thus endanger the bursting of the glass. The fire is allowed to go out; and on breaking the cooled globes, their upper part is found to be lined with sal ammoniac in hemispherical lumps, about 2^ inches thick, of a greyish-white colour, semitransparent, and possessed of a degree of elasticity. 26 pounds of soot yield 6 of sal ammoniac. The ordinary mode of manufacturing sal ammoniac in Eu- rope, is by combining with muriatic acid the ammonia resulting from the igneous decom- position of animal matters in close vessels. Cylinders of cast iron, fitted up as we have described under ACETIC ACID, are charged with bones, horns, parings of hides, and other animal matters ; and being exposed to a full red heat, an immense quantity of an impure liquid carbonate of ammonia distils over. Mr. Minish contrived a cheap method of converting this liquid into sal ammoniac. He digested it with pulverized gypsum, or simply made it percolate through a stratum of bruised gypsum ; whence resulted a liquid sulphate of ammonia, and an insoluble carbonate of lime. The liquid, evaporated to dryness, was mixed with muriute of soda, put into large glass balloons, and de- composed by a subliming heat. Sal ammoniac was found above in its characteristic cake, while sulphate of soda remained below. M. Leblanc of St. Denis, near Paris, in- vented another method of much ingenuity, which is described by a commission of eminent French chemists in the 19th volume of the Annales de Chimie, and in the Journal de Physique for the year 1794. He used tight brick kilns, instead of iron cylinders, for hold- ing the materials to be decomposed. Into one he put a mixture of common salt and oil of vitriol ; into another, animal matters. Heat extricated from the first muriatic acid gas, and from the second ammonia ; which bodies being conducted by their respective flues into a third chamber lined with lead, and containing a stratum of water on its bottom, entered into combination, and precipitated in solid sal am- moniac on the roof and sides, or in liquid at the bottom. In the 20th volume of the Annales, a plan for employing bittern or muriate of magnesia to furnish the acid ingredient is described. An ingenious process on the same principles was some time ago commenced at Borrowstouness in Scotland, by Mr. Astley. He imbued in a stove-room, heated by brick flues, parings of skins, hoins, and other animal matters, with the muriate of magnesia, or mother water of the sea-salt works. The matters thus impregnated and dried were subjected in a close kiln to a red heat, when the sal ammoniac vapour sub- limed, and was condensed either in a solid form, into an adjoining chamber or chimney, or else into a stratum of water on its bottom. Muriate of magnesia at a red heat evolves muriatic acid gas ; an evolution probably aided in the present case by the affinity of ammonia. From coal soot likewise a considerable quantity of ammonia, in the state of carbo- nate and sulphate, may be obtained, either by sublimation or lixiviation with water. These ammoniacal products can afterwards be readily converted into the muriate, as above described. M. Leblanc used a kettle or eolipile for pro- jecting steam into the leaden chamber, to pro- mote the combination. It is evident, that the exact neutralization essential to sal ammoniac might not be hit at first in these operations ; but it could be afterwards affected by the separate addition of a portion of alkaline or acid gas. As the mother waters of the Cheshire salt- works contain only 3^ per cent, of muriate of magnesia, they are not suitable, like those of sea-salt works, for the above manufacture. See SALT. AMMONIAC (GUM). This is a gum resin, which consists, according to Braconnot, of 70 resin, 18.4 gum, 4.4 glutinous matter, 6 water, and 1.2 loss in 100 parts. It forms a milky solution with water; is partially soluble in alcohol ; entirely in ether, nitric acid, and alkalies. Sp. gr. 1.200. It has rather a heavy smell, and a bitter-sweet taste. It is in small agglutinated pieces of a yellowish-white colour. It is used in medicine as an expectorant and antispasmodic. AMMONITES. These petrifactions, which have likewise been distinguished by the name of cornua ammonis, and are called snake-stones by the vulgar, consist chiefly ef lime-stone. They are found of all sizes, from the breadth of half an inch to more than two feet in dia- meter ; some of them rounded, others greatly compressed, and lodged in different strata of stones and clays. They appear to owe their origin to shells of the nautilus kind. AMOMUM. See PIMENTO. AM PE LITE. The aluminous ampelite, is the alum slate, and the graphic, the graphic slate. AMPHIBOLE. See HORNBLENDE and ACTYNOLITE. AMPHIBOLITES. In geology, trap rocks, the basis of which is amphibole or horn- blende. AMPHIGENE. See VESUVIAN. AMYGDALOID. A compound mineral, consisting of spheroidal particles or vesicles of lithomarge, green earth, calc spar, steatite, imbedded in a basis of fine-grained green stone, or wacke, containing sometimes also crystals of hornblende, AMYLINE or AMYDINE. Saussure exposed a solution of starch in twelve times its weight of water to the air in a shallow capsule for two years. It had then become a grey liquid, covered with mould, free from smell, and without action on vegetable blue colours. L 2 ANA 148 ANA The starch had lost nearly one-fourth of its weight, and the remainder was converted into the following substances. 1, Sugar, amounting to one half of the starch ; 2, gum, or a sub- stance analogous to it, obtained by roasting starch ; 3, amyline ; 4, starchy lignine ; 5, lignine mixed with charcoal. Amyline is in- termediate between gum and starch. It is soluble in boiling water,, and the solution affords by evaporation a pale semi-transparent brittle substance, insoluble in alkohol, but soluble in ten times its weight of cold water, and to any extent in water at 144. The solution becomes a white paste, with subacetate of lead. With iodine it becomes blue. It is precipitated by barytes water, but not by lime water, potash, soda, or galls. Phil. Trans. 1819. ANACARDIUM, cashew nut, or mark- ing nut At one extremity of the fruit of the cashew tree is a flattish kidney-shaped nut, between the rind of which and the thin outer shell is a small quantity of a red, thickish, inflammable, and very caustic liquor. This liquor forms an useful marking ink, as any thing written on linen or cotton with it is of a brown colour, which gradually grows blacker, and is very durable. ANALCIME. Cubic zeolite. This mi- neral is generally found in aggregated or cubic crystals, whose solid angles are replaced by three planes. External lustre between vitreous and pearly ; fracture, flat conchoidal ; colours, white, grey, or reddish; translucent. From its becoming feebly electrical by heat it has got the name analcime. Its sp. gr. is less than 2.6. It consists of 58 silica, 18 alumina, 2 lime, 10 soda, 8A water, and 3 loss in 100 parts. It is found in granite, gneiss, trap rocks and lavas, at Calton Hill Edinburgh, at Talisker in Sky, in Dumbartonshire, in the Hartz, Bohemia, and at the Ferroe Islands. The variety found at Somma has been called sarco- lite, from its flesh colour. ANALYSIS. Chemical analysis consists of a great variety of operations, performed for the purpose of separating the component parts of bodies. In these operations the most extensive knowledge of such properties of bodies as are already discovered must be applied, in order to produce simplicity of effect, and cer- tainty in the results. Chemical analysis can- not be executed with success, by one who is not in possession of a considerable number of simple substances in a state of great purity, which, from their effects, are called reagents. The word analysis is applied by chemists to denote that series of operations by which the component parts of bodies are determined, whether they be merely separated, or exhibited apart from each other ; or whether these di- stinctive properties be exhibited by causing them to enter into new combinations. The forming of new combinations is called synthe sis; and, in the chemical examination of bodies, analysis or separation can scarcely ever be effected, without synthesis taking place at the same time. As most of the improvements in the science of chemistry consist in bringing the art of analysis nearer to perfection, it is not easy to give any other rule to the learner than the general one of consulting and remarking the processes of the best chemists, such as Scheele, Bergman, Klaproth, Kirwan, Vauquelin, and Berzelius. The bodies which present them- selves more frequently for examination than others are minerals and mineral waters. In the examination of the former, it was the habit of the earlier chemists to avail themselves of the action of fire, with very few humid pro- cesses, which are such as might be performed in the usual temperature of the atmosphere. Modern chemists have improved the process by fire, by a very extensive use of the blowpipe (see BLOWPIPE); and have succeeded in determining the component parts of minerals to great accuracy in the humid way. For the method of analyzing mineral waters, see WATERS (MINERAL); and for the analysis of metallic ores, see ORES. Several authors have written on the exami- nation of earths and stones. The first step in the examination of consist- ent earths or stones is somewhat different from that of such as are pulverulent. Their specific gravity should first be examined ; also their hardness, whether they will strike fire with steel, or can be scratched by the nail, or only by crystal, or stones of still greater hardness : also their texture, perviousness to light, and whether they be manifestly homogeneous or compound species, &c. 2d, In some cases, we should try whether they imbibe water, or whether water can ex- tract any thing from them by ebullition or digestion. 3d, Whether they be soluble in, or effervesce with acids, before or after pulverization; or whether decomposable by boiling in a strong solution of potash, &c., as gypsums and pon- derous spars are. 4th, Whether they detonate with nitre. 5th, Whether they yield the fluor acid by distillation with sulphuric acid, or ammonia by distilling them with potash. 6th, Whether they be fusible per se with a blowpipe, and how they are affecied by soda, borax, and microcosmic salt; and whether they decrepitate when gradually heated. 7th, Stones that melt per se with the blow- pipe are certainly compound, and contain at least three species of earth, of which the cal- careous is probably one ; and if they give fire with steel, the siliceous is probably another. The general process prescribed by the celebrated Vauquelin, in the 30th volume of the Ann ales de Chimie, is the clearest which has yet been offered to the chemical student. ANA 149 ANA If the mineral be very hard, it is to be ignited in a covered crucible of platinum, and then plunged into cold water, to render it brittle and easily pulverizable. The weight should be noted before and after this operation, in order to see if any volatile matter has been emitted. For the purpose of reducing stones to an impalpable powder, little mortars of highly hardened steel are now made, consisting of a cylindrical case and pestle. A mortar of agate is also used for subsequent levigation. About ten grains of the mineral should be treated at once ; and after the whole 100 grains have been reduced in succession to an impal- pable powder, they should be weighed, to find what increase may have been derived from the substance of the agate. This addition may be regarded as silica. Of the primary earths, only four are usually met with in minerals, viz. silica, alumina, magnesia, and lime, associated with some me- tallic oxides, which are commonly iron, man- ganese, nickel, copper, and chromium. If neither acid nor alkali be expected to be present, the mineral is mixed in a silver cru- cible, with thrice its weight of pure potash and z\ little water. Heat is gradually applied to the covered crucible, and is finally raised to redness; at which temperature it ought to be maintained for an hour. If the mass, on in- spection, be a perfect glass, silica may be re- garded as the chief constituent of the stone ; but if the vitrification be very imperfect, and the bulk much increased, alumina may be supposed to predominate. A brownish or dull green colour indicates the presence of iron ; a bright grass-green, which is imparted to water, that of manganese ; and from a greenish- yellow, chromium may be expected. The crucible, still a little hot, being first wiped, is put into a capsule of porcelain or platinum ; when warm distilled water is poured upon the alkaline earthy mass, to detach it from the crucible. Having transferred the whole of it into the capsule, muriatic acid is poured on, and a gentle heat applied, if necessary, to ac- complish its solution. If the liquid be of an orange-red colour, we infer the presence of iron ; if of a golden-yellow, that of chromium ; and if of a purplish-red, that of manganese. The solution is next to be evaporated to dry- ness, on a sand bath, or over a lamp, taking care so to regulate the heat that no particles be thrown out. Towards the end of the eva- poration, it assumes a gelatinous consistence. At this period it must be stirred frequently with a platinum spatula or glass rod, to pro- mote the disengagement of the muriatic acid gas. After this, the heat may be raised to fully 212 F. for a few minutes. Hot water is now to be poured on in considerable abund- ance, which dissolves every thing except the silica. By filtration, this earth is separated from the liquid ; and being edulcorated with hot water, it is then dried, ignited, and weighed. It constitutes a fine white powder, insoluble in acids, and feeling gritty between the teeth. If it be coloured, a little dilute muriatic acid must be digested on it, to remove the adhering metallic particles, which must be added to the first solution. This must now be reduced by evaporation to the bulk of half a pint. Car- bonate of potash being then added, till it in- dicates alkaline excess, the liquid must be made to boil for a little. A copious precipi- tation of the earth and oxides is thus produced. The whole is thrown on a filter, and after it is so drained as to assume a semi-solid con- sistence, it is removed by a platinum blade, and boiled in a capsule for some time, with solution of pure potash. Alumina and glu- cina are thus dissolved, while the other earths and the metallic oxides remain. This alkalino-earthy solution, separated from the rest by filtration, is to be treated with an excess of muriatic acid; after which carbonate of ammonia being added also in excess, the alumina is thrown down while the glucina con- tinues dissolved. The first earth separated by filtration, washed, dried, and ignited, gives the quantity of alumina. The nature of this may be further demonstrated, by treating it with dilute sulphuric acid, and sulphate of potash, both in equivalent quantities, when the whole will be converted into alum. (See ALUM). The filtered liquid will deposit its glucina, on dissipating the ammonia, by ebul- lition. It is to be separated by filtration, to be washed, ignited, and weighed. The matter undissolved by the digestion of the liquid potash may consist of lime, mag- nesia, and metallic oxides. Dilute sulphuric acid must be digested on it for some time. The solution is to be evaporated to dryness, and heated to expel the excess of acid. The saline solid matter being now diffused in a moderate quantity of water, the sulphate of magnesia will be dissolved, and, along with the metallic sulphates, may be separated from the sulphate of lime by the filter. The latter being washed with a little water, dried, ignited, and weighed, gives, by the scale of equivalents, the quantity of lime in the mineral. The magnesian and metallic solution being diluted with a large quantity of water is to be treated with bicarbonate of potash, which will precipi- tate the nickel, iron, and chromium, but retain the magnesia and manganese, by the excess of carbonic acid. Hydrosulphuret of potash will throw down the manganese, from the mag- nesian solution. The addition of pure potash, aided by gentle ebullition, will then precipitate the magnesia. The oxide of manganese may be freed from the sulphuretted hydrogen, by ustulation. The mingled metallic oxides must be di- gested with abundance of nitric acid, to acidify the chromium. The liquid is next treated with potash, which forms a soluble chromate, while it throws down the iron and nickel. The ANA 150 ANA chromic acid may be separated from the potash by muriatic acid, and digestion with heat, washed, dried till it become a green oxide, and weighed. The nickel is separated from the iron, by treating their solution in muriatic acid, with water of ammonia. The latter oxide which falls may be separated by the filter, dried and weighed. By evaporating the liquid, and exposing the dry residue to a moderate heat the ammoniacal salt will sub- lime, and leave the oxide of nickel behind. The whole separate weights must now be col- lected in one amount, and if they constitute a sum within two per cent, of the primitive weight, the analysis may be regarded as giving a satisfactory account of the composition of the mineral. But if the deficiency be con- siderable, then some volatile ingredient, or some alkali or alkaline salt, may be suspected. A portion of the mineral broken into small fragments, is to be ignited in a porcelain re- tort, to which a refrigerated receiver is fitted. The water or other volatile and condensable matter, if any be present, will thus be ob- tained. But if no loss of weight be sustained by ignition, alkali, or a volatile acid, may be looked for. The latter is usually the fluoric. It may be expelled by digestion with sulphuric acid. It is exactly characterized by its pro- perty of corroding glass. Beside this general method, some others may be used in particular cases. Thus, to discover a small proportion of alumina or magnesia in a solution of a large quantity of lime, pure ammonia may be ap- plied, which will precipitate the alumina or magnesia (if any be), but not the lime. Dis- tilled vinegar applied to the precipitate will discover whether it be alumina or magnesia. 2dly, A minute portion of lime or barytes, in a solution of alumina or magnesia, may be discovered by the sulphuric acid, which pre- cipitates the lime and barytes: the solution should be dilute, else the alumina also would be precipitated. If there be not an excess of acid, the oxalic acid is still a nicer test of lime : 100 grains of gypsum contain about 33 of lime ; 1 00 grains of sulphate of barytes con- tain 66 of barytes; 100 grains of oxalate of lime contain 43.8 of lime. The insolubility of sulphate of barytes in 500 times its weight of boiling water sufficiently distinguishes it. From these data the quantities are easily in- vestigated. 3<%, A minute proportion of alumina in a large quantity of magnesia may be discovered, either by precipitating the whole, and treating it with distilled vinegar; or by heating the solution nearly to ebullition, and adding more carbonate of magnesia, until the solution is perfectly neutral, which it never is when alu- mina is contained in it, as this requires an ex- cess of acid to keep it in solution. By these means the alumina is precipitated in the state of embryon alum, which contains about half its weight of alumina, (or, for greater exact- ness, it may be decomposed by boiling it in volatile alkali). After the precipitation the solution should be largely diluted, as the sul- phate of magnesia, which remained in solution while hot, would precipitate when cold, and mix with the embryon alum. 4thly, A minute portion of magnesia in a large quantity of alumina is best separated by precipitating the whole, and treating the pre- cipitate with distilled vinegar. Lastly, Lime and barytes are separated by precipitating both with the sulphuric acid, and evaporating the solution to a small com- pass, pouring off the liquor, and treating the dried precipitate with 500 times its weight of boiling water; what remains undissolved is sulphate of barytes. The inconveniences of employing much heat are obvious, and Mr. Lowitz informs us that they may be avoided without the least disadvantage. Over the flame of a spirit lamp, that will hold an ounce and half, and is placed in a cylindrical tin furnace, four inches high and three in diameter, with air-holes, and a cover perforated to hold the crucible, he boils the stone prepared as directed above, stirring it frequently. His crucible, which, as well as the spatula, is of very fine silver, holds two ounces and a half, or three ounces. As soon as the matter is boiled dry, he pours in as much hot water as he used at first ; and this he repeats two or three times more, if the re- fractoriness of the fossil require it. Large tough bubbles arising during the boiling are in general a sign that the process will be at- tended with success. Even the sapphire, though the most refractory of all Mr. Lowitz tried, was not more so in this than in the dry way. Sir H. Davy observes, that boracic acid is very useful in analyzing stones that contain a fixed alkali ; as its attraction for the different earths at the heat of ignition is considerable, and the compounds it forms with them are easily decomposed by the mineral acids, dis- solved in water. His process is as follows : Let 100 grains of the stone to be examined be reduced to a fine powder, mixed with 200 grains of boracic acid, and fused for about half an hour at a strong red heat in a crucible of platina or silver. Digest the fused mass in an ounce and half of nitric acid, diluted with seven or eight times the quantity of water, till the whole is decomposed ; and then eva- porate the solution till it is reduced to an ounce and half, or two ounces. If the stone contained silex, it will separate in this process, and must be collected on a filter, and edulco- rated with distilled water, to separate the saline matter. The fluid, mixed with all the water that has been passed through the filter, being evaporated till reduced to about half a pint, is to be saturated with carbonate of am- monia, and boiled with an excess of this salt, ANA 151 ANA till all that will precipitate has fallen down. The earths and metallic oxides being sepa- rated by filtration, mix nitric acid with the clear fluid till it has a strongly sour taste, and then evaporate till the boracic acid remains free. Filter the fluid, evaporate it to dryness, and expose it to a heat of 450 F. when the nitrate of ammonia will be decomposed, and the nitrate of potash or soda will remain in the vessel. The earths and metallic oxides, that remained on the filter, may be distinguished by the common processes. The alumina may be separated by solution of potash, the lime by sulphuric acid, the oxide of iron by succinate of ammonia, the manganese by hydrosulphuret of potash, and the magnesia by pure soda. Lately carbonate or nitrate of barytes, and carbonate with nitrate of lead, have been in- troduced into mineral analysis with great ad- vantage, for the fluxing of stones that may contain alkaline matter. See the English Translation of M. Thenard's volume on analysis. M. Berzelius has more recently employed fluoric acid in a very ingenious manner for the analysis of siliceous minerals. In extracting lithia, for example, from triphane or spodu- mene, he mixes the mineral in powder, with twice its weight of pulverized fluor spar, and with sulphuric acid ; he then heats the mix- ture so that the fluoric acid shall carry off the silica in the form of fluo-silicic acid gas, and he afterwards separates the sulphate of lithia from the residuary matter by solution. Under the head of mineral analysis, nothing is of so much general importance as the exa- mination of soils, with a view to the improve- ment of such as are less productive, by sup- plying the ingredients they want in due proportions to increase their fertility. To Lord Dundonald and Mr. Kirwan we are much indebted for their labours in this field of inquiry ; but Sir H. Davy, assisted by the labours of these gentlemen, the facts and ob- servations of Mr. Young, and his own skill in chemistry, having given at large, in a man- ner best adapted for the use of the practical farmer, an account of the methods to be pur- sued for this purpose, we shall here copy them. The substances found in soils are certain mixtures or combinations of some of the primitive earths, animal and vegetable matter in a decomposing state, certain saline com- pounds, and the oxide of iron. These bodies always retain water, and exist in very different proportions in different lands, and the end of analytical experiments is the detection of their quantities and mode of union. The earths commonly found in soils are principally silex, or the earth of flints ; alu- mina, or the pure matter of clay; lime, or calcareous earth ; and magnesia : for the cha- racters of which see the articles. Silex com- poses a considerable part of hard gravelly soils, hard sandy soils, and hard stony lands. Alumina abounds most in clayey soils, and clayey loams ; but even in the smallest par- ticles of these soils it is generally united with silex and oxide of iron. Lime always exists in soils in a state of combination, and chiefly with carbonic acid, when it is called carbonate of lime. This carbonate in its hardest state is marble; in its softest, chalk. Lime united with sulphuric acid is sulphate of lime, or gypsum ; with phosphoric acid, phosphate of lime, or the earth of bones. Carbonate of lime, mixed with other substances, composes chalky soils and marles, and is found hi soft sandy soils. Magnesia is rarely found in soils ; when it is, it is combined with carbonic acid, or with silex and alumina. Animal decomposing matter exists in different states, contains much carbonaceous substance, volatile alkali, inflammable aeriform products, and carbonic acid. It is found chiefly in lands lately manured. Vegetable decomposing mat- ter usually contains still more carbonaceous substance, and differs from the preceding, principally in not producing volatile alkali. It forms a great proportion of all peats, abounds in rich mould, and is found in larger or smaller quantities in all lands. The saline compounds are few, and in small quantity: they ara chiefly muriate of soda, or common salt, sulphate of magnesia, muriate and sul- phate of potash, nitrate of lime, and the mild alkalis. Oxida of iron, which is the same with the rust produced by exposing iron to air and water, is found in all soils, but most abundantly in red and yellow clays, and red and yellow siliceous sands. The instalments requisite for the analysis of soils are few. A pair of scales capable of holding a quarter of a pound of common soil, and turning with a single grain when loaded : a set of weights from a quarter of a pound troy to a grain : a wire sieve, coarse enough to let a peppercorn pass through: an Argand lamp and stand : a few glass bottles, Hessian crucibles, and china or queen's ware evapo- rating basins : a Wedgwood pestle and mortar : some filters made of half a sheet of blotting paper, folded so as to contain a pint of liquid, and greased at the edges : a bone knife ; and an apparatus for collecting and measuring aeriform fluids. The reagents necessary are muriatic acid, sulphuric acid, pure volatile alkali dissolved in water, solution of prussiate of potash, soap lye, and solutions of carbonate of ammonia, muriate of ammonia, neutral carbonate of pot- ash, and nitrate of ammonia. 1. When the general nature of the soil of a field is to be ascertained, specimens of it should be taken from different places, two or three inches below the surface, and examined as to the similarity of their properties. It some- times happens, that on plains the whole of the upper stratum of the land is of the same kind, and in this case one analysis will be sufficient ANA 152 ANA But in valleys, and near the beds of rivers, there are very great differences, and it now and then occurs, that one part of a field is cal- careous, and another part siliceous ; and in this and analagous cases, the portions different from each other should he analyzed separately. Soils when collected, if they cannot be ex- amined immediately, should be preserved in phials quite rilled with them, and closed with ground glass stopples. The most convenient quantity for a perfect analysis is from two hundred grains to four hundred. It should be collected in dry weather, and exposed to the air till it feels dry. Its specific gravity may be ascertained, by introducing into a phial, which will contain a known quantity of water, equal bulks of water and of the soil ; which may easily be done, by pouring in water till the phial is half full, and then add- ing the soil till the fluid rises to the mouth. The difference between the weight of the water, and that of the soil, will give the re- sult. Thus if the bottle will contain four hundred grains of water, and gains two hun- dred grains when half filled with water and half with soil, the specific gravity of the soil will be 2 ; that is, it will be twice as heavy as water : and if it gained one hundred and sixty-five grains, its specific gravity would be 1825, water being 1000. It is of importance that the specific gravity of a soil should be known, as it affords an indication of the quan- tity of animal and vegetable matter it contains, these substances being always most abundant in the lighter soils. The other physical pro- perties of soils should likewise be examined before the analysis is made, as they denote, to a certain extent, their composition, and serve as guides in directing the experiments. Thus siliceous soils are generally rough to the touch, and scratch glass when rubbed upon it : alu- minous soils adhere strongly to the tongue, and emit a strong earthy smell when breathed upon ; and calcareous soils are soft, and much less adhesive than aluminous soils. 2. Soils, when as dry as they can be made by exposure to the air, still retain a consi- derable quantity of water, which adheres with great obstinacy to them, and cannot be driven off without considerable heat : and the first process of analysis is to free them from as much of this water as possible, without affect- ing their composition in other respects. This may be done by heating the soil for ten or twelve minutes in a china basin over an Argand lamp, at a temperature equal to 300 F. ; and if a thermometer be not used, the proper degree of heat may easily be ascer- tained by keeping a piece of wood in the basin in contact with its bottom ; or as long as the colour of the wood remains unaltered, the heat is not too high ; but as soon as it begins to be charred, the process must be stopped. In several experiments, in which Sir H Davy collected the water that came over at this degree of heat, he found it pure, without any sensible quantity of other volatile matter being produced. The loss of weight in this process must be carefully noted ; and if it amount to 50 grains in 400 of the soil, this may be considered as in the greatest decree absorbent and retentive of water, and will generally be found to contain a large propor- tion of aluminous earth : if the loss be not more than 10 or 20 grains, the land may be considered as slightly absorbent and retentive, and the siliceous earth as most abundant. 3. None of the loose stones, gravel, or large vegetable fibres, should be separated from the soil, till the water is thus expelled ; for these bodies are often highly absorbent and reten- tive, and consequently influence the fertility of the land. But after the soil has been heated as above, these should be separated by the sieve, after the soil has been gently bruised in a mortar. The weights of the vegetable fibres or wood, and of the gravel and stones, should be separately noted down, and the nature of the latter ascertained : if they be calcareous, they will effervesce with acids; if siliceous, they will scratch glass; if aluminous, they will be soft, easily scratched with a knife, and incapable of effervescing with acids. 4. Most soils, besides stones and gravel, contain larger or smaller proportions of sand of different degrees of fineness ; and the next operation necessary is to separate this sand from the parts more minutely divided, such as clay, loam, marl, and vegetable and animal matter. This may be done sufficiently by mixing the soil well with water; as the coarse sand will generally fall to the bottom in the space of a minute, and the finer in two or three ; so that by pouring the water off after one, two, or three minutes, the sand will be for the most part separated from the other substances ; which, with the water containing them, must be poured into a filter. After the water has passed through, what remains on the filter must be dried and weighed ; as must also the sand ; and their respective quantities must be noted down. The water must be preserved, as it will contain the saline matter, and the soluble animal or vegetable matter, if any existed in the soil. 5. A minute analysis of the sand thus se- parated is seldom or never necessary, and its nature may be detected in the same way as that of the stones and gravel. It is always siliceous sand, or calcareous sand, or both together. If it consist wholly of carbonate of lime, it will dissolve rapidly in muriatic acid with effervescence ; but if it consists partly of this and partly of siliceous matter, a residuum will be left after the acid has ceased to act on it, the acid being added till the mixture has a sour taste, and has ceased to effervesce. This residuum is the siliceous part ; which being washed, dried, and heated strongly in a cru- cible, the difference of its weight from that of ANA 153 ANA the whole, will indicate the quantity of the calcareous sand. 6. The finely divided matter of the soil is usually very compound in its nature ; it sometimes contains all the four primitive earths of soils, as well as animal and vege- table matter ; and to ascertain the proportions of these with tolerable accuracy is the most difficult part of the subject. The first process to be performed in this part of the analysis is the exposure of the tine matter of the soil to the action of muriatic acid. This acid, di- luted with double its bulk of water, should be poured upon the earthy matter in an evaporat- ing basin, in a quantity equal to twice the weight of the earthy matter. The mixture should be often stirred, and suffered to remain for an hour, or an hour and half, before it is examined. If any carbonate of lime, or of magnesia, exist in the soil, they will have been dissolved in this time by the acid, which sometimes takes up likewise a little oxide of iron, but very seldom any alumina. The fluid should be passed through a filter; the solid matter collected, washed with distilled or rain water, dried at a moderate heat, and weighed. Its loss will denote the quantity of solid mat- ter taken up. The washings must be added to the solution ; which, if not sour to the taste, must be made so by the addition of fresh acid ; and a little solution of prussiate of potash must be mixed with the liquor. If a blue precipitate occur, it denotes the presence of oxide of iron, and the solution of the prussiate must be dropped in, till no further effect is produced. To ascertain i^s quantity, it must be collected on a filter in the same manner as the other solid precipitates, and heated red : the result will be oxide of iron. Into the fluid freed from oxide of iron, a solution of car- bonate of potash must be poured, till all effer- vescence ceases in it, and till its taste and smell indicate a considerable excess of alkaline salt. The precipitate that falls down is carbonate of lime, which must be collected on a filter, dried at a heat below that of redness, and afterward weighed. The remaining fluid must be boiled for a quarter of an hour, when the magnesia, if there be any, will be precipitated combined with carbonic acid, and its quantity must be ascertained in the same manner as that of the carbonate of lime. If any minute proportion of alumina should, from peculiar circum- stances, be dissolved by the acid, it will be found in the precipitate with the carbonate of lime, and it may be separated from it by boiling for a few minutes with soap lye suffi- cient to cover the solid matter : for this lye dissolves alumina, without acting upon car- bonate of lime. Should the finely divided soil be sufficiently calcareous to effervesce very strongly with acids, a simple method of ascer- taining the quantity of carbonate of lime, suffi- ciently accurate in all common cases, may be adopted. As carbonate of lime in all its states contains a determinate quantity of acid, which is about 44 parts in a hundred by weight, the quantity of this acid given out during the effervescence occasioned by its solution in a stronger acid will indicate the quantity of carbonate of lime present. Thus, if you weigh separately one part of the matter of the soil, and two parts of the acid diluted with an equal quantity of water, and mix the acid slowly in small portions with the soil, till it ceases to occasion any effervescence, by weigh- ing the mixture, and the acid that remains, you will find the quantity of carbonic acid lost ; and for every four grains and half so lost, you will estimate ten grains of carbonate of lime. You may also collect the carbonic acid in the pneumatic apparatus for the analysis of soils^ described in the article JL*A- BORATORY ; and allow for every ounce measure of the carbonic acid, two grains of carbonate of lime. 7- The quantity of insoluble animal and vegetable matter may next be ascertained with sufficient precision, by heating it to a strong red heat in a crucible over a common fire, till no blackness remains in the mass, stirring it frequently meanwhile with a metallic wire. The loss of weight will ascertain the quantity of animal and vegetable matter there was, but not the proportions of each. If the smell emitted, during this process, resemble that of burnt feathers, it is a certain indication of the presence of some animal matter ; and a copious blue flame almost always denotes a consider- able proportion of vegetable matter. Nitrate of ammonia, in the proportion of twenty grains to a hundred of the residuum of the soil, will greatly accelerate this process, if the operator be in haste ; and not affect the result, as it will be decomposed and evaporate. 8. What remains after this decomposition of the vegetable and animal matter consists generally of minute particles of earthy matter, which are usually a mixture of alumina and silex with oxide of iron. To separate these, boil them two or three hours in sulphuric acid diluted with four times its weight of wa- ter, allowing a hundred and twenty grains of acid for every hundred grains of the residuum. If any thing remain undissolved by this acid, it may be considered as silex, and be separated, washed, dried, and weighed in the usual manner. Carbonate of ammonia b^ing added to the solution in quantity more than sufficient to saturate the acid, the alumina will be precipitated ; and the oxide of iron, if any, may be separated from the remaining liquid by boiling it. It scarcely ever happens that any magnesia or lime escapes solution in the muriatic acid ; but if it should, it will be found in the sulphuric acid ; from which it may be separated as directed above for the muriatic. This method of analysis is suffi- ANA 154 ANA ciently precise for all common purposes ; but if very great accuracy be an object, the resi- duum after the incineration must be treated with potash, and in the manner in which stones are analyzed, as given in the first part of this article. 9. If the soil contained any salts, or soluble vegetable or animal matter, they will be found in the water used for separating the sand. This water must be evaporated to dryness at a heat below boiling. If the solid matter left be of a brown colour, and inflammable, it may be considered as partly vegetable extract. If its smell, when exposed to heat, be strong and fetid, it contains animal, mucilaginous, or ge- latinous matter. If it be white and trans- parent, it may be considered as principally saline. Nitrate of potash or of lime is indicated in this saline matter by its sparkling when thrown on burning coals : sulphate of mag- nesia may be detected by its bitter taste ; and sulphate of potash produces no alteration in a solution of carbonate of ammonia, but pre- cipitates a solution of muriate of barytes. 10. If sulphate or phosphate of lime be suspected in the soil, a particular process is requisite to detect it. A given weight of the entire soil, as four hundred grains for instance, must be mixed with one-third as much pow- dered charcoal, and kept at a red heat in a crucible for half an hour. The mixture must then be boiled a quarter of an hoar in half a pint of water, and the solution, being filtered, exposed some days to the open air. If any notable quantity of sulphate of lime, or gyp- sum, existed in the soil, a white precipitate will gradually form in the fluid, and the weight of it will indicate the proportion. Phosphate of lime, if any be present, may be separated from the soil after the process for gypsum. Muriatic acid must be digested upon the soil in quantity more than sufficient to saturate the soluble earths. The solution must be evaporated, and water poured upon the solid matter. This fluid will dissolve the compounds of earths with the muriatic acid, and leave the phosphate of lime untouched. 11. When the examination of a soil is com- pleted, the products should be classed, and their quantities added together ; and if they nearly equal the original quantity of soil, the analysis may be considered as accurate. It must however be observed, that when phos- phate or sulphate of lime is discovered by the independent process, No. 10, just mentioned, a correction must be made for the general pro- ress by subtracting a sum equal to their weight from the quantity of carbonate of lime obtained by precipitation from the muriatic acid. In arranging the products, the form should be in the order of the experiments by which they are obtained. Thus 400 grains of a good siliceous sandy soil maybe supposed to contain grains. Of water of absorption, . . .18 Of loose stones and gravel, principally siliceous, 42 Of undecompounded vegetable fibres, . 10 Of fine siliceous sand, ... . 200 Of minutely divided matter, separated by filtration, and consisting of Carbonate of lime, . . .25 Carbonate of magnesia, . . 4 Matter destructible by heat, prin- cipally vegetable, . .10 Silex, 40 Alumina, . . . .32 Oxide of iron, ... 4 Soluble matter, principally sul- phate of potash and vegetable extract, .... 5 Gypsum, .... 3 Phosphate of lime, ... 2 125 Amount of all the products, Loss, .... 395 5 400 In this instance the loss is supposed small ; but in general, in actual experiments, it will be found much greater, in consequence of the difficulty of collecting the whole quantities of the different precipitates ; and when it is within thirty for four hundred grains, there is no rea- son to suspect any want of due precision in the processes. 12. When the experimenter is become ac- quainted with the use of the different instru- ments, the properties of the reagents, and the relations between the external and chemical qualities of soils, he will seldom find it neces- sary to perform, in any one case, all the processes that have been described. When his soil, for instance, contains no notable pro- portion of calcareous matter, the action of the muriatic acid, No. 6. may be omitted : in examining peat soils, he will principally have to attend to the operation by fire and air, No. 7- ; and in the analysis of chalks and loams, he will often be able to omit the expe- riment with sulphuric acid, No. 8. In the first trials that are made by persons unacquainted with chemistry, they must not expect much precision of result. Many dif- ficulties will be met with ; but in overcoming them the most useful kind of practical know- ledge will be obtained ; and nothing is so in- structive in experimental science as the detec- tion of mistakes. The correct analyst ought to be well grounded in general chemical in- formation ; but perhaps there is no better mode of gaining it than that of attempting original investigations. In pursuing his ex- periments, he will be continually obliged to learn from books the history of the substances ANA 165 ANA he Is employing or acting upon ; and his theo- retical ideas will be more valuable in being connected with practical operation, and ac- quired for the purpose of discovery. The analysis of vegetables requires various manipulations, and peculiar attention, as their principles are extremely liable to be altered by the processes to which they are subjected. It was long before this analysis was brought to any degree of perfection. Some of the immediate materials of vege- tables are separated to our hands by Nature in a state of greater or less purity, as the gums, resins, and balsams, that exude from plants. The expressed juices contain various matters, that may be separated by the appropriate re- agents. Maceration, infusion, and decoction in water, take up certain parts soluble in this menstruum ; and alcohol will extract others that water will not dissolve. The mode of separating and distinguishing these materials will easily be collected from their characters, as given under the head VEGETABLE KING- DOM, and under the different articles them- selves. As the ultimate constituents of all vegetable substances are carbon, hydrogen, and oxygen, with occasionally azote, the problem of their final analysis resolves into a method of ascer- taining the proportion of these elementary bodies. MM. Gay Lussac and Thenard con- trived a very elegant apparatus for vegetable and animal analysis, in which the matter in a dried state was mixed with chlorate of potash, and formed into minute pellets. These pellets being projected through the intervention of a stop-cock of peculiar structure into an ignited glass tube, were instantly resolved into carbonic acid and water. The former product was re- ceived over mercury, and estimated by its con- densation with potash ; the latter was inter- cepted by ignited muriate of lime, and was measured by the increase of weight which it communicates to this substance. By previous trials, the quantity of oxygen which a given weight of the chlorate of potash yielded by ignition was known ; and hence the carbon, hydrogen, and oxygen, derived from the or- ganic substance, as well as the residual azote, of the gaseous products. M. Berzelius modified the above apparatus, and employed the organic product in combi- nation with a base, generally oxide of lead. He mixed a certain weight of this neutral com- pound with a known quantity of pure chlorate of potash, and triturated the whole with a large quantity of muriate of soda, for the pur- pose of moderating the subsequent combustion. This mingled dry powder is put into a glass tube about half an inch diameter, and eight or ten inches long, which is partially enclosed in a fold of tin-plate, hooped with iron wire. One end of the tube is hermetically sealed beforehand, the other is now drawn to a pretty fine point by the blowpipe. This termination is inserted into a glass globe about an inch diameter, which joins it to a long tube con- taining dry muriate of lime in its middle, and dipping at its other extremity into the mercury of a pneumatic trough. The first tube, with its protecting tin case, being exposed gradually to ignition, the enclosed materials are resolved into carbonic acid, water, and asote, which come over, and are estimated as above de- scribed. M. Gay Lussac has more recently employed peroxide of copper to mix with the organic substance to be analyzed; because while it yields its oxygen to hydrogen and carbon, it is not acted on by azote ; and thus the errors resulting from the formation of nitric acid with the chlorate of potash are avoided. Berzelius has afforded satisfactory evidence by his analyses, that the simple apparatus which he employed is adequate to every purpose of chemical research. Dr. Prout has described, in the Annals of Philosophy for March 1820, a very neat form of apparatus for completing analysis of organic substances with the heat of a lamp. Hydrogen having the power in minute quantities of modifying the constitu- tion of the organic bodies, requires to be esti- mated with corresponding minuteness. Mr. Porrett has very ingeniously suggested, that its quantity may be more accurately determined by the proportion of oxide of copper that is revived, than by the product of water. Dilute sulphuric acid being digested on the residual cupreous powder will instantly dissolve the oxide, and leave the reduced metal; whose weight will indicate, by the scale of equivalents, the hydrogen expended in its reduction. One of hydrogen corresponds to 9 of water, and to 32 of copper. From my experiments, I find that this pro- posal of Mr. Porrett will not suit in practice, for much of the peroxide of copper is occa- sionally reduced merely to the state of prot- oxide. Under the different vegetable and animal products, we shall take care to state their ultimate constituents by the most correct and recent analysis. The peculiar substances which water, alcohol, ether, and other solvents, can separate from an organic body, may be called the immediate products of the vegetable or animal kingdom ; while the carbon, hydrogen, oxygen, and azote, discoverable by igneous analysis, are the ultimate constituent elements. To the former class belong sugar, gum, starch, oils, resins, gelatin, urea, organic acids, and alkalies, &c. which see. The following account of my mode of exe- cuting the ultimate analysis of organic pro- ducts is extracted from a paper which the Royal Society did me the honour to insert in their Transactions for 1822. The improvements lately introduced into the analysis of vegetable and animal com- pounds, with the investigation of the equi- valent ratios, in which their constituent ele- ANA 156 ANA ments, carbon, hydrogen, oxygen, and azote are associated, have thrown an unexpected light into this formerly obscure province of chemical science. While the substitution by M. Gay Lussac, of black oxide of copper for the chlorate of potash, has given peculiar fa- cility and elegance to animal analysis, it may be doubted whether, in those cases where the main object of inquiry is the proportion of carbon, it has not, frequently, led to fallacious results. As the quantity of this element is in- ferred from the volume of carbonic acid evolved in the decomposition of the organic matters, such of their particles as happen not to be in immediate contact with the cupreous oxide, will remain unconverted into carbonic acid; and thus the proportion of carbon will come to be underrated ; an accident which cannot occur with chlorate of potash, since the carbonaceous matter is here plunged in an ignited atmo- sphere of oxygen. It is probably to this cause that we must refer the discrepant results in the analysis of pure sugar, between MM. Gay Lussac, Thenard, and Bcrzelius, on the one hand, and Dr. Prout, on the other ; the former gentlemen assigning about 43 parts in the hundred of carbon, while the latter states the carbon at only 40. The objects of the present paper are, first, to indicate, and endeavour to remove several sources of fallacy attending the method with peroxide of copper ; and next, to exhibit the results of its application to a considerable series of vegetable and animal compounds. Peroxide of copper, prepared by igniting the pure nitrate of this metal, is, like yellow oxide of lead, and many other metallic oxides, readily absorbent of a small portion of hu- midity ftom the air, the quantity of which de- pends, in some measure, on the length of time during which it has suffered ignition. If ex- posed to a red heat, merely till the vapours of nitric acid are expelled, 100 grains of the oxide will absorb, in the ordinary state of the atmosphere, from one-tenth to two-tenths of a grain of moisture in the space of an hour or two ; and about one-half of the above quan- tity in a very few minutes. The French che- mists, who have operated most with this agent, seem to be well aware of this circumstance, for they direct the peroxide to be used immedi- ately after ignition, and to be triturated with the organic matter in a hot mortar of agate or glass. Yet this precaution will not entirely prevent the fallacy arising from the hygrome- tric action ; for I find that peroxide thus treated does absorb, during the long trituration es- sential to the process, a certain quantity of moisture, which, if not taken into account, will produce serious errors in the analytical results. It is better therefore to leave the powdered peroxide intended for research ex- posed for such time to the air as to bring it to hygrometric repose, then to put it up in a phial, and by igniting one hundred grains of it in a proper glass tube, sealed at one end, and loosely closed with a glass plug at the other, to determine the proportion of moisture which it contains. This, then, indicates the constant quantity to be deducted from the loss of weight which the peroxide suffers hi the course of the experiment. The mortar should be perfectly dry, but not warm. Experimenters have been at great pains to bring the various organic objects of research to a state of thorough desiccation before mixing them with the peroxide of copper ; but this practice introduces a similar fallacy to that above described. We ought, therefore, after having made them as dry as possible by the joint agencies of heat, and an absorbent sur- face of sulphuric acid in vacuo, to expose them to the air till they also come into hygrometric repose, noting the quantity of moisture which they imbibe, that it may be afterwards allowed for. The plan which I adopt for the purpose of desiccation seems to answer very well. Having put the pulverulent animal or vege- table matter into short phials, furnished with ground glass stoppers, I place the open phials in a large quantity of sand, heated to 212 F. in a porcelain capsule, and set this over a sur- face of sulphuric acid in an exhausted receiver. After an hour or more the receiver is removed, and the phials instantly stopped. The loss of weight shows the total moisture which each of them has parted with ; while the subsequent increase of their weight, after leaving them unstopped for some time in the open air, indi- cates the amount of hygrometric absorption. This is consequently the quantity to be de- ducted in calculating experimental results. Many chemists, particularly in this coun- try, have employed the heat of a spirit-lamp, instead of that produced by the combustion of charcoal, for igniting the tube in which the mixed materials are placed. I have compared very carefully both methods of heating, and find that for many bodies, such as coal and resin, which abound in carbon, the flame of the lamp is insufficient ; while its application being confined at once to a small portion of the tube, that uniform ignition of the whole, desirable towards the close of the experiment, cannot be obtained. I was hence led to contrive a pe- culiar form of furnace, in which, with a hand- ful of charcoal, reduced to bits about the size of small filberts, an experiment may be com- pleted without anxiety or trouble, in the space of half an hour. Since I have operated with this instrument, the results on the same body have been much more consistent than those previously obtained with the lamp ; and it is so convenient, that I have sometimes finished eight experiments in a day. Fig. 1. (Plate VI.) represents the whole apparatus, as when in action. Fig. 2. is a horizontal section of the furnace, in which we perceive a semi-cylinder of thin sheet-iron, about eight inches long and 3 wide, perforated ANA 157 ANA with holes, and resting on the edge of a hollow prism of tin-plate, represented more distinctly in fig. 3. where n shows a slit, through which the sealed end of the glass tube may be made to project, on occasion, i is a handle attached to the semi-cylinder, by which it may be slid backwards or forwards, and removed at the end of the process, d is a sheath of platinum foil, which serves, by aid of a wire laid across, to support the middle of the tube, when it is softened by ignition. At g, the plates whirh close the ends of the semi-cylinder and tin- plate prism, rise up a few inches to screen the pneumatic apparatus from the heat. A third occasional screen of tin-plate is hung on at /. All these are furnished with slits for the pass- age of the glass tube. This is made of crown glass, and is generally about 9 or ] inches long, and 3-10ths of internal diameter. It is connected with the mercurial cistern by a nar- row tube and caoutchouc collar. This tube has a syphon form, and rises about an inch within the graduated receiver at e. By this arrangement, should the collar be not abso- lutely air-tight, the pressure of the column of mercury causes the atmospheric air to enter at the crevice, and bubbles of it will be seen rising up without the application of heat At the end of the operation, the point of the tube e is always left above the surface of the mer- cury, the quantity of organic matter employed being such as to produce from G to 7 cubic inches of gaseous product, the volume of the graduated receiver being 7 cubic inches. As the tubes with which I operate have all the same capacity, viz. half a cubic inch ; and as the bulk of materials is the same in all the experiments, one experiment on the analysis of sugar or resin gives the volume of atmo- spheric air due to the apparatus ; which volume is a constant quantity in the same circum- stances of ignition. And since the whole ap- paratus is always allowed to cool to the atmo- spheric temperature, the volume of residual gas in the tubes comes to be exactly known, being equal, very nearly, to the primitive volume of atmospheric air left after the absorption of the carbonic acid in the sugar or resin experi- ment*. Thus this quantity, hitherto ill appre- ciated or neglected in many experiments, though it is of very great consequence, may be accurately found. At A\ fig. 2. a little tin- plate screen is shown. It is perforated for the passage of the tube, and may be slid along, and left at any part of the semi-cylindric cage, so as to preserve from the influence of the heat any requisite portion of the sealed end of the tube. At fig. 4. is seen the shape of the little * If a be the capacity of the graduated re- ceiver, and 6 the spare capacity of the tubes, then the above volume is 6 a+b bulb, into which I introduce the proper weight of ether, alcohol, naphtha, or other volatile liquids, which are destined for analysis. After weighing it exactly, it is immediately slid down to the bottom of the tube, and covered with 150 or 200 grains of peroxide of copper. The bulb has a capacity equal to 3 grain measures of water, and its capillary point is sometimes closed with an inappreciably small quantity of bees-wax, to prevent the exhalation of the liquid, till the peroxide be ignited. b is a cover to the furnace, with an oblong orifice at its top. It serves for a chimney, and may be applied or removed by means of its handle, according as we wish to increase or diminish the heat, cc are tin cases enclosing corks, through which the iron wires are passed, that support the whole furnace at any conve- nient height and angle of inclination. The tightness of the apparatus at the end of the process is proved by the rising of the mercury in the graduated receiver, by about one tenth of an inch, as the tube becomes refrigerated. My mode of operating with the peroxide of copper is the following : I triturate very carefully in a dry glass mortar, from 1 to 2 grains of the matter to be analyzed, with from 100 to 140 grains of the oxide. I then transfer it, by means of a platinum-foil tray and small glass funnel, into the glass tube, clearing out the mortar with a metallic brush. Over that mixture I put 20 or 30 grains of the peroxide itself, and next, 50 or 60 grains of clean copper filings. The remaining part of the tube is loosely closed with 10 or 12 grains of amianthus, by whose capillary attraction the moisture evolved in the experiment is rapidly withdrawn from the hot part of the tube, and the risk of its frac- ture thus completely obviated. The amian- thus serves moreover as a plug, to prevent the projection of any minute particles of filings, or of oxide, when the filings are not present. The tube is now weighed in a very delicate balance, and its weight is written down. A little cork, channelled at its side, is next put into the tube, to prevent the chance of mercury being forced backwards into it, by any acci- dental cooling or condensation. The collar of caoutchouc is finally tied on, and the tube is placed, as is shown in fig. 2. but without the plate &, which is employed merely in the case of analyzing volatile liquids. A few fragments of ignited charcoal are now placed under the tube, at the end of the furnace next to the cis- tern, and the remaining space in the semi- cylinder is tilled up with bits of cold charcoal. The top, J, may then be put in its place, when the operation will proceed spontaneously, the progressive advance of the ignition from one end to the other being proportioned to the ex- pansion of glass, so that the tube very seldom cracks in the process. Indeed I have often used the same tube for a dozen experiments, in the ANA 158 ANA course of which it became converted into vitrite, or Reaumur's porcelain. Since the evolved gas is saturated with moisture, I reduce it to the volume of dry gas, by help of the following table, computed by the well known formula from my table of the elastic force of steam, which the Royal Society did me the honour to publish in their Trans- actions for the year 1818. Tempera- ture. Multiplier. Tempera- ture. Multiplier. Tempera- ture. Multiplier. 53 F. 54 55 56 57 58 59 0.9870 0.9864 0.9858 0.9852 0.9846 0.9839 0.9833 60 F. 61 62 63 64 65 66 0.9827 98.20 98.13 98.06 97-99 97-93 97-86 67<> F. 68 69 70 71 72 73 97.79 97.72 97-65 0.9758 0.9751 0.9743 0-9735 In certain cases, where the quantity of hy- drogen is small, or where, as in the example of indigo, its presence has been denied, I employ pulverulent protochloride of mercury (calomel) instead of peroxide of copper. The organic compound being intimately mixed with that powder, and gently heated, the muriatic acid gas obtained demonstrates the presence, though half of its volume will not give the total quantity, of hydrogen ; for a proportion of this elementary body continues associated with oxygen in the state of water. Dry oxalate of lead, treated in this way, yields not the slight- est trace of muriatic acid ; for, on passing the disengaged gas through a dilute solution of nitrate of silver, no precipitation or even cloud of chloride is produced. But 5 grains of in- digo, prepared from the deoxidized solution of the dyer's vat, and freed from its lime and resin by the successive application of dilute muriatic acid and alcohol, gave 5 cubic inches of muriatic acid gas when heated along with 150 grains of calomel. Here we have a quan- tity of gas equivalent to 2^ cubic inches of hydrogen. By means of peroxide of copper, however, nearly 4 times the above quantity of hydrogen may be obtained from the same weight of indigo. I shall now give in detail one example of the mode of computing the relation of the constituents from the experimental results, and shall then state the other analyses in a tabular form, subjoining a few remarks on the habitudes of some peculiar bodies. 1.4 grains of sulphuric ether, specific gra- vity 0.70, being slowly passed in vapour from the glass bulb through 200 grains of ignited peroxide of copper, yielded 6.8 cubic inches of carbonic acid gas at 66 F. which are equiva- lent to 6.57128 of dry gas at 60. This number being multiplied by 0.127 = the carbon in 1 cubic inch of the gas, the product 0.8345256, is the carbon in 1.4 grains of ether ; and 0.8345256 X | = 2.2254 = the oxygen equivalent to the carbonic acid. The tube was found to have lost 4.78 grains in weight, 0.1 of which was due to the hygrometric moist- ure in the oxide, and 1.4 to the ether. The remainder, 3.28, is the quantity of oxygen abstracted from the oxide by the combustible elements of the ether. But of these 3.28 grains, 2.2254 went to the formation of the carbonic acid, leaving 1.0546 of oxygen, equi- valent to 0.1318 of hydrogen. Hence, 1.4 ether, by this experiment, which is taken as the most satisfactory of a great number, seem to consist of Carbon, 0.8345 Hydrogen, 0.1318 Water, 0.4337 1.4000 And in 1 grain we shall have, Carbon, 0.5960 3 atoms 2.25 Hydrogen, 0.1330 4 atoms 0.50 Oxygen, 0.2710 1 atom 1.00 60.00 13.33 26.66 3.75 100.0 X 0.9722 = 2.9168 X 0.625 = 1.25 1.0000 Or, 3 vols olef. gas = 3 2 vap. of water 2 4.1666 The proportion of the constituents of sul- phuric ether, deduced by M. Gay Lussac from the experiments of M. Th. de Saussure, are 2 volumes olefiant gas -{- 1 volume vapour of water, which 3 volumes are condensed into 1 of vapour of ether, having a specific gravity = 2.58. The ether which I used had been first distilled off dry carbonate of potash, and then digested on dry muriate of lime, from which it was simply decanted, according to the injunction of M. de Saussure. Whether my ether contained more alcoholic matter than that employed by the Genevese philosopher, or whether the difference of result is to be ascribed to the difference in the mode of ana- lysis, must be decided by future researches. By analogous modes of reduction, the re- suits were deduced from my experiments. 1 ANH 159 ANI ought here to state, than in many cases the materials, after being ignited in the tube, and then cooled, were again triturated in the mor- tar, and subjected to a second ignition. Thus, none of the carbon could escape conversion into carbonic acid. I was seldom content with one experiment on a body : frequently six or eight were made. ANATASE. Octohedrite, oxide of tita- nium, rutile, and titane rutile. This mineral shows a variety of colours by reflected light, from indigo-blue to reddish-brown. By trans- mitted light it appears greenish-yellow. It is found usually in small crystals, octohedrons, with isosceles triangular faces. Structure la- mellar ; it is semitransparent, or opaque, fragments splendent, adamantine, scratches glass, brittle, sp. gr. 3.85. It is a pure oxide of titanium. It has been found only in Dau- phiny and Norway ; and is a very rare mineral. It occurs in granite, gneiss, mica slate, and transition lime-stone. ANDALUSITE. A massive mineral, of a flesh and sometimes rose-red colour. It is, however, occasionally crystallized in rectangu- lar four-sided prisms, verging on rhomboids. The structure of the prisms is lamellar, with joints parallel to their sides. Translucent, scratches quartz ; is easily broken ; sp. gr. 3.165. Infusible by the blowpipe ; in which respect it differs from felspar, though called felspath apyre by Hauy. It is composed of 52 alumina, 32 silica, 8 potash, 2 oxide of iron, and 6 loss. Vauq. It belongs to pri- mitive countries, and was first found in Anda- lusia in Spain. It is found in mica slate in Aberdeenshire, and in the Isle of Unst ; Dart- moor in Devonshire ; in mica slate at Killiney, near Dublin, and at Douce Mountain, county Wicklow. ANDREOLITE. See HARMOTOME. ANHYDRITE. Anhydrous gypsum. There are six varieties of it. 1. Compact has various shades, of white, blue, and red ; massive and kidney-shaped ; dull aspect ; splintery or conchoidal fracture ; translucent on the edges : is scratched by fluor, but scratches calc spar; somewhat tough; specific gravity 2.850. It is dry sulphate of lime, with a trace of sea salt. It is found in the salt mines of Austria and Salzburg, and at the foot of the Harz mountains. 2. Granular, the scaly of Jameson, is found in massive con- cretions, of which the structure is confusedly foliated. White or bluish colour, of a pearly lustre ; composition as above, with one per cent, of sea salt. It occurs in the salt mines of Halle; sp. gr. 2.957. 3. Fibrous. Massive; glimmering, pearly lustre ; fracture in delicate parallel fibres ; scarcely translucent ; easily broken. Found at Halle, Ischel, and near Brunswick. 4. Radiated. Blue sometimes spotted with red; radiated, splendent frac- ture; partly splintery ; translucent; not hard; p. gr. 2,940. 5. Sparry, or cube spar. Milk- white colour, passing sometimes into greyish and reddish- white ; short four-sided prisms, having two of the opposite sides much broader than the other two ; and occasionally the lateral edges are truncated, whence results an eight- sided prism ; lustre splendent, pearly. Foli- ated fracture. Threefold rectangular cleavage. Cubical fragments. Translucent. Scratches calc spar. Brittle. Sp. gr. 2.9. This is the muriacite of some writers. It is doubly re- fracting. It is said to contain 1 per cent, of sea salt. It is found at Bex in Switzerland, and Halle in the Tyrol. 6. Siliciferous, or vulpinite. Massive concretions of a laminated structure, translucent on the edges, splendent and brittle. Greyish- white, veined with bluish- grey. Sp. gr. 2.88. It contains eight per cent, silex. The rest is sulphate of lime. It is called by statuaries, Marmo bardiglio di Ber- gamo, and takes a fine polish. It derives its name from Vulpino in Italy, where it accom- panies lime. ANHYDROUS. Destitute of water. ANIL, or NIL. This plant, from the leaves of which indigo is prepared, grows in America. ANIMAL KINGDOM. Animal bodies may be considered as peculiar apparatus for carrying on a determinate series of chemical operations. Vegetables seem capable of ope- rating with fluids only, and at the temperature of the atmosphere, as we have just noticed. But most animals have a provision for me- chanically dividing solids by mastication, which answers the same purpose as grinding, pounding, or levigation does in our experi- ments ; that is to say, it enlarges the quantity of surface to be acted upon by solvents. The process carried on in the stomach appears to be of the same kind as that which we distin- guish by the name of digestion ; and the bowels, whatever other uses they may serve, evidently form an apparatus for filtering or conveying off the fluids ; while the more solid parts of the aliments, which are probably of such a nature as not to be rendered fluid, but by an alteration which would perhaps destroy the texture of the machine itself, are rejected as useless. When this filtered fluid passes into the circulatory vessels, through which it is driven with considerable velocity by the mechanical action of the heart, it is subjected not only to all those changes which the chemi- cal action of its parts is capable of producing, but is likewise exposed to the air of the atmo- sphere in the lungs, into which that elastic fluid is admitted by the act of respiration. Here it undergoes a change of the same nature as happens to other combustible bodies when they combine with its vital part, or oxygen. This vital part becomes condensed, and com- bines with the blood, at the same time that it gives out a large quantity of heat, in conse- quence of its own capacity for heat being diminished. A small portion of azote like- ANI 160 ANI wise is absorbed, and carbonic acid is given out. Some curious experiments of Spallan- zani show, that the lungs are not the sole organs by which these changes are effected. Worms, insects, shells of land and sea animals, egg shells, fishes, dead animals, and parts of animals, even after they have become putrid, are capable of absorbing oxygen from the air, and giving out carbonic acid. They deprive atmospheric air of its oxygen as completely as phosphorus. Shells, however, lose this pro- perty when their organization is destroyed by age. Amphibia, deprived of their lungs, lived much longer in the open air, than others in air destitute of oxygen. It is remarkable, that a larva, weighing a few grains, would consume almost as much oxygen in a given time as one of the amphibia a thousand times its bulk. Fishes, alive and dead, animals, and parts of animals, confined under water in jars, absorbed the oxygen of the atmospheric air over the water. Muscles, tendons, bones, brain, fat, and blood, all absorbed oxygen in different proportions, but the blood did not absorb most ; and bile appeared not to absorb any. It would lead us too far from our purpose, if we were to attempt an explanation of the little we know respecting the manner in which the secretions or combinations that produce the various animal and vegetable substances are effected, or the uses of those substances in the economy of plants and animals. Most of them are very different from any of the pro- ducts of the mineral kingdom. We shall therefore only add, that these organized beings are so contrived, that their existence continues, and all their functions are performed, as long as the vessels are supplied with food or mate- rials to occupy the place of such as are car- ried off by evaporation from the surface or otherwise, and as long as no great change is made, either by violence or disease, in those vessels, or the fluids they contain. But as soon as the entire process is interrupted in any very considerable degree, the chemical arrange- ments become altered, the temperature in land animals is changed, the minute vessels are acted upon and destroyed, life ceases, and the admirable structure, being no longer suffi- ciently perfect, loses its figure, and returns, by new combinations and decompositions, to the general mass of unorganized matter, with a rapidity which is usually greater the more elaborate its construction. The parts of vegetable or animal substances may be obtained, for chemical examination, either by simple pressure, which empties the vessels of their contents ; by digestion in water, or in other fluids, which dissolve certain parts, and often change their nature ; by destructive distillation, in which the application of a strong heat alters the combination of the parts, and causes the new products to pass over into the receiver in the order of their volatility; by spontaneous decomposition or fermentation, wherein the component parts take a new ar- rangement, and form compounds which did not for the most part exist in the organized substance; or, lastly, the judicious chemist will avail himself of all these several methods singly, or in combination. He will, accord- ing to circumstances, separate the parts of an animal or vegetable substance by pressure, assisted by heat ; or by digestion or bailing in various fluids added in the retort which con- tains the substance under examination. He will attend particularly to the products which pass over, whether they be permanently elas- tic, or subject to condensation in the tempera- tures we are able to produce. In some cases, he will suffer the spontaneous decomposition to precede the application of chemical me- thods ; and in others he will attentively mark the changes which the products of his opera- tions undergo in the course of time, whether in closed vessels, or exposed to the open air. Thus it is that, in surveying the ample field of nature, the philosophical chemist possesses numerous means of making discoveries, if applied with judgment and sagacity ; though the progress of discovery, so far from bringing us nearer the end of our pursuit, appears con- tinually to open new scenes, and, by enlarging our powers of investigation, never fails to point out additional objects of inquiry. Animal and vegetable substances approach each other by insensible gradations ; so that there is no simple product of the one which may not be found in greater or less quantity in the other. The most general distinctive character of animal substances is that of afford- ing volatile alkali by destructive distillation. Some plants, however, afford it likewise. Neither contain it ready formed ; but it ap- pears to be produced by the combination of hydrogen and azote, during the changes pro- duced either by fire, or by the putrefactive process. See AMMONIA. Our knowledge of the products of the ani- mal kingdom, by the help of chemical analysis, is not yet sufficiently matured to enable us to arrange them according to the nature of thefc component parts; which appear to consist chiefly of hydrogen, oxygen, carbon, and azote ; and with these sulphur, phosphorus, lime, magnesia, and soda, are frequently com- bined in variable proportions. The following are the peculiar chemical products of animal organization. Gelatin, albumen, fibrin, caseous matter, colouring matter of blood, mucus, urea, picromel, os- mazome, sugar of milk, and sugar of diabetes. The compound animal products are the vari- ous solids and fluids, whether healthy or mor- bid, that are found in the animal body ; such as muscle, skin, bone, blood, urine, bile, mor- bid concretions, brain, &c. When animal substances are left exposed to the air, or immersed in water or other fluids, ANN 161 ANT they suffer a spontaneous change, which is more or less rapid according to circumstances. The spontaneous change of organized bodies is distinguished by the name of fermentation. In vegetable bodies there are distinct stages or periods of this process, which have been divided into the vinous, acetous, and putre- factive fermentations. Animal substances are susceptible only of the two latter, during which, as in all other spontaneous changes, the combinations of chemical principles be- come in general more and more simple. There is no doubt but much instruction might be obtained from accurate observations of the putrefactive processes in all their several va- rieties and situations ; but the loathsomeness and danger attending on such inquiries have hitherto greatly retarded our progress in this department of chemical science. See FER- MENTATION (PUTREFACTIVE). ANIME, improperly called gum anime, is a resinous substance imported from New Spain and the Brazils. There are two kinds, di stinguished by the names of oriental and occi- dental. The former is dry, and of an uncer- tain colour, some specimens being greenish, some reddish, and some of the brown colour of myrrh. The latter is in yellowish- white, transparent, somewhat unctuous tears, and partly in larger masses, brittle, of a light pleasant taste, easily melting in the fire, and burning with an agreeable smell. Like resins, it is totally soluble in alcohol, and also in oil. Water takes up about l-16th of the weight of this resin by decoction. The spirit, drawn off by distillation, has a considerable degree of the taste and flavour of the anime ; the dis- tilled water discovers on its surface some small portion of essential oil. This resin is used by perfumers, and also in certain plasters, wherein it has been sup- posed to be of service in nervous affections of the head and other parts; but there are no reasons to think that, for medical purposes, it differs from common resins. ANNEAL. We know too little of the arrangement of particles to determine what it is that constitutes or produces brittleness in any substance. In a considerable number of instances of bodies which are capable of un- dergoing ignition, it is found that sudden cooling renders them hard and brittle. This is a real inconvenience in glass, and also in steel, when this metallic substance is required to be soft and flexible. The inconveniencies are avoided by cooling them very gradually, and this process is called annealing. Glass vessels, or other articles, are carried into an oven or apartment near the great furnace, called the leer, where they are permitted to cool, in a greater or less time, according to their thickness and bulk. The annealing of steel, or other metallic bodies, consists simply in heating them, and suffering them to cool again, either upon the hearth of the furnace, or in any other situation where the heat is moderate, or at least the temperature is not very cold. ANNOTTO. The pellicles of the seeds of the Mxa orellana, a liliaceous shrub, from 15 to 20 feet high in good ground, afford the red masses brought into Europe under the name of Annotto, Orlean, and Roucou. The annotto commonly met with among us is moderately hard, of a brown colour on the outside, and a dull red within. It is diffi- cultly acted upon by water, and tinges the liquor only of a pale brownish-yellcw colour. In rectified spirit of wine it very readily dis- solves, and communicates a high orange or yellowish-red. Hence it is used as an ingre- dient in varnishes, for giving more or less of an orange cast to the simple yellows. Sulphuric ether is the best solvent of an- notto. Potash and soda, either caustic or carbonated, dissolve annotto in great quanti- ties ; from which solutions it is thrown down by acids in small flocks. The alkaline solu- tions are of a deep red colour. Chlorine de- colours the alcoholic solution of annotto ; the liquor becoming speedily white and milky. If strong sulphuric acid be poured on annotto in powder, the red colour passes immediately to a very fine indigo blue; but this tint is not permanent : it changes to green, and finally to violet, in the course of 24 hours thereafter. This property of becoming blue belongs also to saffron. Nitric acid, slightly heated on annotto, sets it on fire; and a finely divided charcoal remains. Annotto is soluble both in essential oils, as oil of turpentine, and in fixed oils. Bcussingault Ann. de Chim. et de Phyt. xxviii. 440. Beside its use in dyeing, it is employed for colouring cheese. ANORTHITE. The primitive form of this mineral is a doubly oblique prism. The lustre of the cleavages is pearly, and that of the conchoidal fracture vitreous. The crystals of anorthite are clear and transparent, but small. Sp. grav. 2-763. Strong muriatic acid entirely decomposes it. It consists of silica, 44.49; alumina, 34.46; oxide of iron, 0-74; lime, 15.68; magnesia, 5.26. Rose. The name anorthite, signifying without right an- gles, distinguishes it from felspar, two of whose cleavages are at right angles to each other. ANTHOPHYLLITE. A massive mine- ral of a brownish colour ; sometimes also crys- tallized, in thin flat six-sided prisms, streaked lengthwise. It has a false metallic lustre, glistening and pearly. In crystals, transparent. Massive, only translucent on the edges. It does not scratch glass, but fluate of lime. Specific gravity 3.2. Somewhat hard, but exceedingly brittle. Infusible alone before the blowpipe, but with borax it gives a grass- green transparent bead. It consists of 66 silica, 13.3 alumina, 14 magnesia, 3.33 lime, ANT 162 ANT 6 oxide of iron, 3 oxide of manganese, 1.43 water, and 2.94 loss in 100. It is found at Konigsber /-v o x^* C*^ I* CO CJ ! IT" tf a Vj ^ ci 8 " o vS" *f5 ci !l CO ? c * > ^d* sf x "~ s o 5* g* 50 1 to 15f p I I ? o ^ ^ I I" * I. ft 3 r 1 w O H o H HH O ill 1 5 P If I* ! O x-v 3 *- O ^ g C5 ATT 187 ATT TABLES OF SIMPLE ELECTIVE ATTRACTIONS, FROM BERGMANN. I.WATER AND COMBUSTIBLE SUBSTANCES. IN THE HUMID WAY. WATER. SULPHUR. SALINE SULPHURETS. ALCOHOL. ETHER. Potash Soda Oxygen Molybdic oxide Oxygen Oxide of gold Water Ether Alcohol Volatile oils Ammonia and acid silver Volatile oils Water Diliquescent salts Alcohol Oxide of lead tin mercury arsenic Ammonia Fixed alkali Sulphur Carbonate of am- silver antimony Alkaline sulphu- monia mercury bismuth rets Ether Sulphuric acid Von-deliquescent salts arsenic antimony iron Potash C J copper tin lead nickel Sulphur Muriates Phosphoric acid boda Barytes ^tronticin. cobalt manganese FAT OILS. VOLATILE OILS. Lime iron Other metallic Barytes ? Ether Magnesia oxides Strontian ? Alcohol Phosphorus Carbon Lime Fat oils Fat oils Water Metallic oxides Fixed alkalis Ammonia Alcohol Ether Sulphur Ether Ether Volatile oils Phosphorus hydrogen Fixed alkalis Ammonia Sulphur Tfcl * . IN THE DRY WAY. Phosphorus SULPHURETTED HYDRO GENT* Oxygen Manganese Potash Iron Barytes Soda Copper Potash tron Tin Soda Copper Lead Lime Tin Silver Ammonia Lead Gold Magnesia Silver Antimony Zircon Cobalt Cobalt Nickel Nickel Bismuth Bismuth Antimony Mercury . Mercury Arsenic i Arsenic Carbon ? Uranium ? Molybdena Tellurium ATT 188 ATT TABLE OF SIMPLE ELECTIVE ATTRACTIONS. II. OXYGEN AND METALS. IN THE HUMID WAY. O Y Vf^TTXT OXIDE OF OXIDE or OXIDE or OXIDE OF OXIDE OF V-A. JL LJ.CJ.N GOLD. SILVER. PLATINA. MERCURY. LEAD. Zinc Acids, gallic Acids, gallic Acids, gallic Acids, gallic Acids, gallic Iron muriatic muriatic muriatic muriatic sulphuric Tin nitric oxalic nitric oxalic mucic Antimony sulphuric sulphuric sulphuric succinic oxalic Arsenic arsenic mucic arsenic phospho- arsenic Lead fluoric phospho- fluoric ric tartaric Bismuth Copper tartaric phospho- ric sulphur- tartaric phospho- sulphuric mucic phospho- ric Platinum ric ous ric tartaric muriatic Mercury f Palladium acetic sebacic nitric arsenic oxalic citric citric malic sulphur- ous J Rhodium ^ Iridium prussic Fixed alkalis fluoric tartaric acetic succinic sulphur- ous suberic nitric V. Osmium Ammonia citric prussic nitric fluoric Silver Sulphuretted succinic carbonic fluoric citric Gold hydrogen acetic Ammonia acetic malic prussic benzoic succinic carbonic boracic acetic Ammonia prussic benzoic carbonic boracic Ammonia prussic carbonic IT 1 11 T IN THE DRY WAY. Fixed alkalis Fat oils Ammonia GOLD. SILVER. PLATINA. MERCURY. LEAD. Titanium \lercury Lead Arsenic Gold Gold Manganese Copper Copper Gold Silver Silver \rr' Zinc Silver Mercury Copper Platina Copper Iron Lead Bismuth Tin Lead Mercury Tin Bismuth Tin Bismuth Tin Bismuth Uranium Tin Gold Zinc Zinc Tin Molybdena Antimony Antimony Antimony Bismuth Antimony Tungsten [ron [ron Nickel Copper Platina Cobalt Platina Manganese Cobalt Antimony Arsenic [Antimony Zinc Zinc Manganese Arsenic Zinc Nickel Nickel Arsenic Iron [ron Nickel Arsenic Arsenic Nickel Lead Alkaline sul- Iron Chromium Cobalt Platina Silver phurets Alkaline sul- Bismuth Lead Manganese Alkaline sul- Alkaline sul- phurets Mercury Alkaline sul- Sulphur phurets Sulphur Copper Tellurium phurets phurets Platinum - Mercury Silver Gold Hydrogen Carbon Boron Phosphor u s The column under oxygen is divided into two parts. The first exhibits the order in which the metals precipitate one another from acid solutions; the Sulphur Azote second, according to Vauquelin, shows the affinities of the metals for oxygen, represented by the difficulty with which their oxides are decomposed by heat. It is different from Bergmahn's column. (Chlorine -* ATT ATT TABLE OF SIMPLE ELECTIVE ATTRACTIONS. METALS (CONTINUED.) IN THE HUMID WAY. OXIDE or OXIDE OF OXIDE OF OXIDE OF OXIDE OF OXIDE OF COPPER. IRON. TIN. BISMUTH. NICKEL. ARSENIC. Acids, gallic Acids, gallic Acids, gallic Acids, oxalic Acids, oxalic Acids, gallic oxalic oxalic tartaric arsenic muriatic muriatic tartaric tartaric muriatic tartaric sulphuric oxalic muriatic campho- sulphuric phospho- tartaric sulphuric sulphuric ric oxalic ric nitric nitric mucic sulphuric arsenic sulphuric sebacic sebacic nitric mucic phospho- muriatic phospho- tartaric arsenic muriatic ric nitric ric phospho- phospho- nitric nitric fluoric fluoric ric ric phospho- succinic mucic mucic fluoric succinic ric fluoric succinic succinic mucic fluoric arsenic mucic citric citric succinic citric fluoric citric acetic acetic citric acetic succinic acetic arsenic prussic arsenic boracic citric boracic boracic carbonic acetic prussic acetic prussic prussic Ammonia prussic carbonic boracic Potash carbonic Fixed alkalis Potash prussic Soda Ammonia Ammonia Soda carbonic Ammonia Fat oils Ammonia Water Compound salts Fat oils IN THE DRY WAY. COPPER. IRON. j TIN. BISMUTH. NICKEL. ARSENIC. Gold Nickel Zinc L/ead fron Nickel Silver Cobalt j Mercury Silver Cobalt Cobalt [ron Manganese Copper Gold Arsenic Copper Arsenic Arsenic Antimony Mercury Copper [ron Manganese Copper Gold Antimony Gold Silver Zinc Gold Silver Tin Tin Tin Antimony Silver Lead Copper Antimony Lead Platina Tin Iron Platina Platina Gold Tin Antimony 'Manganese Nickel Bismuth Platina Lead Platina iNickel Iron Lead Zinc Nickel Bismuth Arsenic Zinc Silver Antimony Bismuth Lead Platina Alkaline sul- Zinc Alkaline sul- Cobalt Alkaline sul- 1 Bismuth phurets Alkaline sul- phurets Mercury phurets Cobalt Sulphur phurets Sulphur Alkaline sul- Sulphur Alkaline sul- Sulphur phurets Sulphur phurets Sulphur ATT ATT ! TABLE OF SIMPLE ELECTIVE ATTRACTIONS. METALS (CONCLUDED.) IN THE HUMID WAY. OXIDE OF OXIDE OF OXIDE OF OXIDE OF OXIDE OF OXIDE OF COBALT. ZINC. ANTIMONY. MANGANESE. TELLURIUM. TITANIUM. Acids, oxalic Acids, gallic Acids, gallic Acids, oxalic Acids, nitric Acids, sulphu- muriatic oxalic muriatic tartaric nitro-mu- ric sulphuric sulphuric benzoic citric riatic nitric tartaric muriatic oxalic fluoric sulphuric muriatic nitric mucic sulphuric phospho- Sulphur prussic phospho- nitric : nitric ric Alkalis ric tartaric tartaric nitric Mercury fluoric phospho- mucic sulphuric mucic ric phospho- muriatic succinic citric ric arsenic " citric succinic citric acetic OXIDE OF acetic fluoric arsenic succinic fliisv*.*;* prussic carbonic URANIUM. arsenic boracic acetic nuonc arsenic Acids, sulphu- prussic boracic acetic ric carbonic prussic boracic nitro-mu- Ammonia carbonic prussic riatic Fixed alkalis carbonic muriatic Ammonia Sulphur nitric Fixed alkalis phospho- Ammonia ric acetic gallic IN THE DRY WAY. prussic carbonic COBALT. ZINC. ANTIMONY. MANGANESE. TELLURIUM. Sulphur [ron Copper Iron Copper Mercury Nickel Antimony Copper Iron Sulphur Arsenic Tin Tin Gold Copper Mercury Lead ; Silver Gold Silver Nickel JTin Platina Gold Silver Alkaline sul- Tin Cobalt Bismuth phurets Antimony Arsenic Zinc Zinc Platina Gold Alkaline sul- Bismuth Platina phurets Lead Mercury Sulphur Nickel Arsenic Iron Cobalt Alkaline sul- phurets Sulphur 1 ATT 191 ATT SCHEME of DOUBLE AFFINITIES in the Humid Way. r "Sulphuric fNitric ji acid acid Sulphate Nitr ate of of < 50 lii ne < * Magnesia Fluoric Sulphuric ^Magnesia acid l_Lime 54 acid Sulphate of lime , j Acetate of potash r Muriatic") ^ A _^ i ' ; 1 " acid fPotash 26 Acetic Arseni- < ous < acid ., 3xygen-) | Oxy- Oxygen Vgenated guj > muriatic JJ2 acid irsemcj acid huret )tash "\ ( _ J [_Sulphur Arsenic acid Sulphate of lime Muriate of potash "Lime 54 Sulphuric r2 MuriatiTS acid acid Sulphuret of lime of p ^Sulphur . _ ft I otash^ 62 + 23_85> 1 Sulphu- ?1 \jcic acid 86 LimeJ Muriate of lime ~" Sulphate of lime Nitre fPotash 58 Nitric"| acid "Potash 62 Sulphu-" ric acid Sulphate of potash Nitrate Mui Vlead ofp 1 Sulphuric Oxide of l_ acid lead _ o^hJ 32 + 54=86 Muriatic?? acid 85 Limej Sulphate *of lime Sulphate of lead Nitrate of ammonia Nitrate of soda Sulphate of am- monia fAmmo- 38 Nitric"! nia acid ! Nitrate < 46 ^ofmer- cury Sulphuric Oxide of | 1 acid mercury J fSoda Nitric" acid imon J salt * :,, Muriatic ^ acid Silver J Nitrate > of silver i J V .. i ^ Sulnhate of mercurv Muriate of silver AUR 192 AXI AUGITE. Pyroxene of HaUy. This mineral is for the most part crystallized in small six or eight-sided prisms, with dihedral summits. It is found also in grains. Its colours are green, brown, and black. Inter- nal lustre shining. Uneven fracture. Trans- lucent. Easily broken. It scratches glass. Sp. gr. 3.3. Melts into a black enamel. Its composition, according to Klaproth, is 48 si- lica, 24 lime, 12 oxide of iron, 8.75 magnesia, 5 alumina, 1 manganese. It is met with among volcanic rocks, but is supposed to have existed prior to the eruption and ejection of the lava. Large crystals of it are also found in basalt, of a finer green, and more brilliant than those found in lavas. It occurs with olivin in the basalt of Teesdale ; in the trap rocks round Edinburgh ; and in several of the Hebrides. Sahlite and coccolite are considered to be varieties of augite. AURUM FULMINANS. See FULMI- NATING. AURUM GRAPHICUM. See ORES of GOLD. AURUM MUSIVUM, or MOSAICUM. A combination of tin and sulphur, which is thus made: Melt twelve ounces of tin, and add to it three ounces of mercury ; triturate this amalgam with seven ounces of sulphur, and three of muriate of ammonia. Put the powder into a matrass, bedded rather deep in sand, and keep it for several hours in a gentle heat ; which is afterward to be raised, and continued for several hours longer. If the heat have been moderate, and not continued too long, the golden-coloured scaly porous mass, called aurum musivum, will be found at the bottom of the vessel ; but if it have been too strong, the aurum musivum fuses to a black mass of a striated texture. This process is thus explained: As the heat increases, the tin, by stronger affinity, seizes and combines with the muriatic acid of the muriate of am- monia; while the alkali of that salt, com- bining with a portion of the sulphur, flies off in the form of a sulphuret. The combination of tin and muriatic acid sublimes ; and is found adhering to the sides of the matrass. The mercury, which served to divide the tin, combines with part of the sulphur, and forms cinnabar, which also sublimes; and the re- maining sulphur, with the remaining tin, forms the aurum musivum which occupies the lower part of the vessel. It must be admitted, how- ever, that this explanation does not indicate the reasons why such an indirect and com- plicated process should be required to form a simple combination of tin and sulphur. It does not appear that the proportions of the materials require to be strictly attended to. The process of the Marquis de Bullion, as described by Chaptal in his Elements of Che- mistry, consists in amalgamating eight ounces of tin with eight ounces of mercury, and mixing this with six ounces of sulphur and four of muriate of ammonia. This mixture is to be exposed for three hours on a sand heat sufficient to render the bottom of the matrass obscurely red-hot. But Chaptal himself found that if the matrass containing the mixture were exposed to a naked fire, and violently heated, the mixture took fire, and a sublimate was formed in the neck of the matrass, con- sisting of the most beautiful aurum musivum in large hexagonal plates. Aurum musivum has no taste, though some specimens exhibit a sulphureous smell. It is not soluble in water, acids, or alkaline solu- tions. But in the dry way it forms a yellow sulphuret, soluble in water. It deflagrates with nitre. Bergman mentions a native aurum musivum from Siberia, containing tin, sulphur, and a small proportion of copper. Aurum musivum is used as a pigment for giving a golden colour to small statue or plaster figures. It is likewise said to be mixed with melted glass to imitate lapis lazuli. Mosaic gold is composed of 100 tin -f- 56-25 sulphur, by Dr. John Davy ; and of 100 tin + 52.3 sulphur, by Professor Ber- zelius; the mean of which, or 100 + 54-2 is probably correct. It will then consist of 1 prime of tin 7-375 + 2 sulphur = 4-0. AVANTUR1NE. A variety of quartz rock containing mica spangles. The most beautiful comes from Spain, but Dr. M'Cul- loch found specimens at Glen Fernat in Scot- land, which, when polished, were equal in beauty to any of the foreign. The most usual colour of the base of avanturine is brown, or reddish-brown, enclosing golden-coloured spangles. AUTOMALITE. This mineral occurs in regular octohedrons, and tetrahedrons. It scratches glass. Sp. gr. 4.26 4.69. It is nearly opaque, the .light transmitted being of a dark bluish-green colour. It is composed of alumina 42 ; silica 4 ; oxide of zinc 28 ; oxide of iron 5 ; sulphur 17 Vauquelin. It is found in a talcose rock at Fahlun in Sweden, and is sometimes called Fahlunite. Philipi Mineralogy. AXE-STONE. A subspecies of jade, from which it differs in not being of so light a green, and in having a somewhat slaty tex- ture. The natives of New Zealand work it into hatchets. It is found in Corsica, Swit- zerland, Saxony, and on the banks of the river Amazon, whence it has been called Amazo- nian stone. Its constituents are silica 50.5, magnesia 31, alumina 10, oxide of iron 5.5, water 2-75, oxide of chromium 0.05. AXINITE, or THUMERSTONE. This mineral is sometimes massive, but most usually crystallized. The crystals resemble an axe in the form and sharpness of their edges ; being flat rhomboidal parallelepipeds, with two of the opposite edges wanting, and a small face instead of each. They are translucent, and BAL 193 BAL of a violet colour, whence called violet schorl. They become electric by heat The usual colour is clove-brown. Lustre splendent. Hard, but yields to the file, and easily broken. Sp. gr. 3.25. It froths like zeolite before the blowpipe, melting into a black enamel, or a dark green glass. According to Vauquelin's analysis, it contains 44 silica, 18 alumina, 19 lime, 14 oxide of iron, and 4 oxide of man- ganese. It is found in beds at Thum in Sax- ony ; in Killas at Botallack near the Land's- end, Cornwall ; and at Trewellard in that neighbourhood. AZOTANE, chloride of azote. See NI- TROGEN. AZOTE. See GAS (NITROGEN). AZURE-STONE, or LAPIS LAZULI. This massive mineral is of a fine azure-blue colour. Lustre glistening. Fine grained uneven fracture. Scratches glass, but scarcely strikes fire with steel. Opaque, or translu- cent on the very edges. Easily broken. Sp. grav. 2.85. In a very strong heat it intu- mesces, and melts into a yellowish black mass. After calcination it forms a jelly with acids. It consists of 46 silica, 28 lime, 14.5 alumina, 3 oxide of iron, 6.5 sulphate of lime, and 2 water, according to Klaproth. But by a later and most interesting research of MAI. Cle- ment and Desormes, lapis lazuli appears to be composed of 34 silica, 33 alumina, 3 sulphur, and 22 soda. (Ann. de Chimie, torn. 57.) In this analysis, however, a loss of eight per cent, was experienced. These distinguished chemists consider the above ingredients essen- tial, and the 2.4 of lime and 1.5 of iron, which they have occasionally met with, as accidental. It is from azure stone that the beautiful and unchangeable blue colour ultramarine is pre- pared. The finest specimens are brought from China, Persia, and Great Bucharia. They are made red-hot in the fire, and thrown into water to render them easily pulverizable. They are then reduced to a fine powder, and intimately combined with a varnish, formed of resin, wax, and boiled linseed oil. This pasty mixture is put into a linen cloth, and repeatedly kneaded with hot water : the first water, which is usually dirty, is thrown away ; the second gives a blue of the first quality ; and the third yields one of less value. The process is founded on the property which the colouring matter of azure-stone has of adhering less firmly to the resinous cement than the foreign matter with which it is associated. When azure stone has its colour altered by a moderate heat, it is reckoned bad. MM. Clement and Desormes consider the extraction of ultramarine as a species of saponification. AZURITE, or PRISMATIC AZURE SPAR, the LAZULITE of Werner and Hatty. This mineral is often found in oblique quadrangular crystals of a fine blue colour. It is translucent only on the edges, brittle, and nearly as hard as quartz. When massive, it is either in grains, or bits like a hazel nut. It occurs imbedded in mica slate. Its lustre is vitreous. Its constituents are 66 alumina, 18 magnesia, 10 silica, 2.5 oxide of iron, 2 lime. It occurs in Vorau in Stiria, in a gangue of quartz ; but the finest specimens come from the bishopric of Salzburg. BABINGTONITE. A new mineral, in small brilliant crystals, associated with cleavlandite, flesh-coloured felspar, and green amphibole, on a specimen from Arendal. M. Levy in Annals of Phil. vii. 275. BAIKALITE. See TREMOLITE As- BESTIFORM. BALANCE. The beginning and end of every exact chemical process consists in weigh- ing. With imperfect instruments this opera- tion will be tedious and inaccurate; but with a good balance, the result will be satisfactory; and much time, which is so precious in ex- perimental researches, will be saved. The balance is a lever, the axis of motion of which is formed with an edge like that of a knife; and the two dishes at its extremities are hung upon edges of the same kirfd. These edges are first made sharp, and then rounded with a fine hone, or a piece of buff leather. The excellence of the instrument depends, in a great measure, on the regular form of this rounded part. When the lever is considered as a mere line, the two outer edges are called points of suspension, and the inner the ful- crum. The points of suspension are supposed to be at equal distances from the fulcrum, and to be pressed with equal weights when loaded. 1. If the fulcrum be placed in the centre of gravity of the beam, and the three edges lie all in the same right line, the balance will have no tendency to one position more than another, but will rest in any position it may be placed in, whether the scales be on or off, empty or loaded. 2. If the centre of gravity of the beam, when level, be immediately above the fulcrum, it will overset by the smallest action ; that is, the end which is lowest will descend : and it will do this with more swiftness, the higher the centre of gravity, and the less the points of suspension are loaded. 3. But if the centre of gravity of the beam be immediately below the fulcrum, the beam will not rest in any position but when level; HAL BAL and, if disturbed from this position, and then left at liberty, it will vibrate, and at last come to rest on the level. Its vibrations will be quicker, and its horizontal tendency stronger, the lower the centre of gravity, and the less the weights upon the points of suspension. 4. If the fulcrum be below the line joining he points of suspension, and these be loaded, the beam will overset, unless prevented by the weight of the beam tending to produce a hori- zontal position, as in 3. In this last case, small weights will equilibrate, as in 3. ; a certain exact weight will rest in any position of the beam, as in 1. ; and all greater weights will cause the beam to overset, as in 2. Many scales are often made this way, and will overset with any considerable load. 5. If the fulcrum be above the line joining the points of suspension, the beam will come to the horizontal position, unless prevented by its own weight, as in 2. If the centre of gravity of the beam be nearly in the fulcrum, all the vibrations of the loaded beam will be made in times nearly equal, -unless the weights be very small, when they will be slower. The vibrations of balances are quicker, and the horizontal tendency stronger, the higher the fulcrum. 6. If the arms of a balance be unequal, the weights in equipoise will be unequal in the same proportion. It is a severe check upon a workman to keep the arms equal, while he is making the other adjustments in a strong and inflexible beam. 7- The equality of the arms of a balance is of use, in scientific pursuits, chiefly in making weights by bisection. A balance with unequal arms will weigh as accurately as another of the same workmanship with equal arms, pro- vided the standard weight itself be first coun- terpoised, then taken out of the scale, and the thing to be weighed be put into the scale and adjusted against the counterpoise; or when proportional quantities only are considered, as in chemical and in other philosophical experi- ments, the bodies and products under exami- nation may be weighed against the weights, taking care always to put the weights into the same scale. For then, though the bodies may not be really equal to the weights, yet their proportions among each other may be the same as if they had been accurately so. 8. But though the equality of the arms may be well dispensed with, yet it is indispensably necessary that their relative lengths, whatever they may be, should continue invariable. For this purpose, it is necessary, either that the three edges be all truly parallel, or that the points of suspension and support should be always in the same part of the edge. This last requisite is the most easily obtained. The balances made in London are usually constructed in such a manner, that the bearing parts form notches in the other parts of the edges ; so that the scales being set to vibrate, all the parts naturally fall into the same bear- ing. The balances made in the country have the fulcrum edge straight, and confined to one constant bearing by two side plates. But the points of suspension are referred to notches in the edges, like the London balances. The balances here mentioned, which come from the country, are enclosed in a small iron japanned box ; and are to be met with at Birmingham and Sheffield warehouses, though less, fre- quently than some years ago; because a pocket contrivance for weighing guineas and half-guineas has got possession of the market. They are, in general, well made and adjusted, turn with the twentieth of a grain when empty, and will sensibly show the tenth of a grain, with an ounce in each scale. Their price is from five shillings to half a guinea ; but those which are under seven shillings have not their edges hardened, and consequently are not durable. This may be ascertained by the purchaser, by passing the point of a penknife across the small piece which goes through one of the end boxes : if it makes any mark or impression, the part is soft 9. If a beam be adjusted so as to have no tendency to any one position, as in 1. and the scales be equally loaded ; then, if a small weight be added in one of the scales, that balance will turn, and the points of suspension will move with an accelerated motion, similar to that of falling bodies, but as much slower, in proportion, very nearly, as the added weight is less than the whole weight borne by the fulcrum. 10. The stronger the tendency to a hori- zontal position in any balance, or the quicker its vibrations, 3. 5. the greater additional weight will be required to cause it to turn, or incline to any given angle. No balance, therefore, can turn so quick as the motion deduced in 9. Such a balance as is there described, if it were to turn with the ten- thousandth part of the weight, would move at quickest ten thousand times slower than falling bodies ; that is, the dish containing the weight, instead of falling through sixteen feet in a second of time, would fall through only two hundred parts of an inch, and it would require four seconds to move through one-third part of an inch ; consequently all accurate weighing must be slow. If the indices of two balances be of equal lengths, that index which is con- nected with the shorter balance will move proportionally quicker than the other. Long beams are the most in request, because they are thought to have less friction : this is doubtful; but the quicker angular motion, greater strength, and less weight of a short balance, are certainly advantages. 11. Very delicate balances are not only useful in n,ice experiments, but are likewise much more expeditious than others in common weighing. If a pair of scales with a certain BAL 195 BAL load be barely sensible to one-tenth of a grain, it will require a considerable time to ascertain the weight to that degree of accuracy, because the turn must be observed several times over, and is very small. But if no greater accuracy were required, and scales were used which would turn with the hundredth of a grain, a tenth of a grain, more or less, would make so great a difference in the turn, that it would be seen immediately. 12. If a balance be found to turn with a certain addition, and is not moved by any smaller weight, a greater sensibility may be given to that balance, by producing a tremu- lous motion in its parts. Thus, if the edge of a blunt saw, a file, or other similar instru- ment, be drawn along any part of the case or support of a balance, it will produce a jarring, which will diminish the friction on the moving parts so much, that the turn will be evident with one-third or one-fourth of the addition that would else have been required. In this way, a beam which would barely turn by the addition of one-tenth of a grain, will turn with one- thirtieth or fortieth of a grain. 13. A balance, the horizontal tendency of which depends only on its own weight, as in 3. will turn with the same addition, what- ever may be the load; except so far as a greater load will produce a greater friction. 14. But a balance, the horizontal tendency of which depends only on the elevation of the fulcrum, as in 5. will be less sensible the greater the load ; and the addition requisite to produce an equal turn will be in proportion to the load itself. 15. In order to regulate the horizontal ten- dency in some beams, the fulcrum is placed below the points of suspension, as in 4. and a sliding weight is put upon the cock or index, by means of which the centre of gravity may be raised or depressed. This is an useful con- trivance. 16. Weights are made by a subdivision of a standard weight. If the weight be continu- ally halved, it will produce the common pile, which is the smallest number for weighing between its extremes, without placing any weight in the scale with the body under exa- mination. Granulated lead is a very conve- nient substance to be used in this operation of halving, which, however, is very tedious. The readiest way to subdivide small weights con- sists in weighing a certain quantity of small wire, and afterward cutting it into such parts, by measure, as are desired : 01 the wire may be wrapped close round two pins, and then cut asunder with a knife. By this means it will be divided into a great number of equal lengths, or small rings. The wire ought to be so thin, as that one of these rings may barely produce a sensible effect on the beam. If any quan- tity (as, for example, a grain) of these rings be weighed, and the number then reckoned, the grain may be subdivided in any propor- tion, by dividing that number, and making the weights equal to as many of the rings as the quotient of the division denotes. Then, if 750 of the rings amounted to a grain, and it were required to divide the grain decimally, downwards, 9-10ths would be equal to 675 rings, 8-10ths would be equal to 600 rings, 7-10ths to 525 rings, &c. Small weights may be made of thin leaf brass. Jewellers' foil is a good material for weights below l-10th of a grain, as low as to 1-1 00th of a grain; and all lower quantities may be either estimated by the position of the index, or shown by actually counting the rings of wire, the value of which has been determined. 17- In philosophical experiments, it will be found very convenient to admit no more than one dimension of weight. The grain is of that magnitude as to deserve the preference. With regard.to the number of weights the che- mists ought to be provided with, writers have differed according to their habits and views. Mathematicians have computed the least pos- sible number, with which all weights within certain limits might be ascertained; but their determination is of little use. Because, with so small a number, it must often happen, that the scales will be heavily loaded with weights on each side, put in with a view only to deter- mine the difference between them. It is not the least possible number of weights which it is necessary an operator should buy to effect his purpose, that we ought to inquire after, but the most convenient number for ascertaining his inquiries with accuracy and expedition. The error of adjustment is the least possible, when only one weight is in the scale; that is, a single weight of five grains is twice as likely to be true, as two weights, one of three, and the other of two grams, put into the dish to supply the place of the single five ; because each of these last has its own probability of error in adjustment. But since it is as inconsistent with convenience to provide a single weight, as it would be to have a single character for every number ; and as we have nine characters, which we use in rotation, to express higher values according to their position, it will be found very serviceable to make the set of weights correspond with our numerical system. This directs us to the set of weights as follows: 1000 grains, 900 g. 800 g. 700 g. 600 g. 500 g. 400 g. 300 g. 200 g. 1 00 g. 90 g. 80 g. 70 g. 60 g. 50 g. 40 g. 30 g. 20 g. 10 g. 9g. 8g. 7g. 6g. 5g. 4g. 3g. 2g. lg. T %g. -&g. T^g- T*Tg- fVg- T*og' T 3 og' Afr Tog- TT)g' l-fog- T&og' TTTog- TS^g- Wf, g< T*ff g' To g- T*o g- With these the philo- sopher will always have the same number of weights in his scales as there are figures in the number expressing the weights in grains. Thus 742.5 grains will be weighed by the weights 700, 40, 2, and 5-lOths. A balance (made by Ramsden, and turning on points instead of edges) in the possession o2 BAL 19G BAL of Dr. George Fordyce, is mentioned in the seventy-fifth volume of the Philosophical Transactions. With a load of four or five ounces, a difference of one division in the in- dex was made by ^ a 1 ^ 11 - This is ga 4 6 oo' P art of the weight, and consequently this beam will ascertain such weights to five places of figures, beside an estimate figure. The Royal Society's balance, which was lately made by Ramsden, turns on steel edges, upon planes of polished crystal. It is said to ascertain a weight to the seven-millionth part, and it may be used in general practice to de- termine weights to five places and better. From this account of balances, the student may form a proper estimate of the value of those tables of specific gravities, which are carried to five, six, and even seven places of figures, and likewise of the theoretical deduc- tions in chemistry, that depend on a supposed accuracy in weighing, which practice does not authorise. In general, where weights are given to five places of figures, the last figure is an es- timate, or guess figure ; and where they are carried farther, it may be taken for granted, that the author deceives either intentionally, or from want of skill in reducing his weights to fractional expressions, or otherwise. The most exact standard weights were pro- cured, by means of the ambassadors of France, resident in various places ; and these were com- pared by Mons. Tillet with the standard mark in the pile preserved in the Cour de Monnoies de Paris. His experiments were made with an exact balance made to weigh one marc, and sensible to one quarter of a grain. Now, as the marc contains 18432 quarter grains, it fol- lows that this balance was a good one, and would exhibit proportions to four places, and a guess figure. The results are contained in the following table, extracted from Mons. Til- let's excellent paper in the Memoirs of the Royal Academy of Sciences for the year 1767- I have added the two last columns, which show the number of French and English grains contained in the compound quantities against which they stand. The English grains are computed to one-tenth of a grain, although the accuracy of weighing came no nearer than about two-tenths. The weights of the kilogramme, gramme, de- cigramme, and centigramme, which are now frequently occurring in the French chemical writers, are added at the bottom of this table according to their respective values. Table of the Weights of different Countries. Place and Denomination of Weights. Berlin. The marc of 16 loths, . ^ Berne- Goldsmiths' weight of 8 ounces, Berne. Pound of JG ounces for merchan- dise, The common pound varies very consider- ably in other towns of the canton. Berne. Apothecaries' weight of 8 ounces, Bonn, ' ; Brussels. The marc, or original troyes weight, Cologn. The marc of 16 loths, Constantinople. The cheki, or 100 drachms, Copenhagen. Goldsmiths' weight commonly supposed equal to the marc of Cologn, Copenhagen. Merchants' weight of lf> loths, Dantzic weight ; commonly supposed equal to the marc of Cologn, Florence. The pound (anciently used by the Romans), Genoa. The peso sotile, Genoa. The peso grosso, ... Hamburgh weight; commonly supposed equal to the Cologn marc, Hamburgh. Another weight, Liege. The Brussels marc used ; but the weight proved, . . . Lisbon. The marc, or half pound, . London. The pound troy, . . . London. The pound avoirdupois, . Lucca. The pound, . ... Madrid. The marc royal of Castile, Marc. oz. gros. grains. F- grains. E. grains, 7 5 16 4408 3616.3 1 4 4648 3813.2 2 1 * 6 9834 8067-7 7 51 26 4454 3654. _ 7 5 2 6 4398f 3608.6 1 _ 21 4629 3797-6 7 5 11 4403 3612.2 1 2 3 28 6004 4925.6 7 6* 2f 44i% 3641.2 1 1 4702i 3857-9 7 5 3* 4395 3606. 1 3 1 20 6392 5 44. 1 2 2-S- 30 5970 4897-7 1 2 3 5 5981 4906.7 __ 7 5 7| 4399| 3609.4 7 7 23 4559 3740.2 1 __ __ 24 4632 3800-1 1 7 4 3 34 1 4318 7021 3542.4 5760- 1 6 el 6 8538 7004-5 1 3 23 63594- 5217. 7 4 8* 4328 3550-7 197 BAL Place and Denomination of Weights. Malta. The pound, . Manheim. (The Cologn marc,) Milan. The marc, .... Milan. The libra grossa, Munich. (The Cologn marc,) Naples. The pound of 12 ounces, . Ratisbon. The weight for gold of 128 crowns, ..... Ratisbon. The weight for ducats: of 64 ducats, . Ratisbon. The marc of 8 ounces, . . Ratisbon. The pound of 16 ounces, - .., Rome. The pound of 12 ounces, . t {Stockholm. The pound of 2 marcs, Stuttgard. (The Cologn marc,) Turin. The marc of b ounces, At Turin they have also a pound of 1 2 of the above ounces. But, in their apo- thecaries' pound of 12 ounces, the ounce is one-sixth lighter. Warsaw. The pound, . . . : , ., Venice. The libra grossa of 12 ounces, . Venice. The peso sottile of 12 ounces, In the bounds dependent on Venice, the pound differs considerably in each. Vienna. The marc of commerce, . ,; -^ Vienna. The marc of money, . .* England. The grain, .... France. The grain, . . . ..;.-.. The kilogramme, ...i. .,,, .,. , The gramme, The decigramme, The centigramme, . . , ,-*, ; See TABLE of WEIGHTS and MEASURES in the Appendix. BAL Mar oz. gros grain F. grains E grains. 1 2 2A 21 5961 4890.4 7 5 10 4402 3611.5 7 5 33^ 4425 3660.2 3 7 14364 11784. 7 5 11 4403 3612.3 1 2 3* 27 6039 ..4954.3 1 6 24 8088 6635.3 7 2 32 4208 3452.3 1 24 4632 3800.1 2 2 4^ 6 10698 8776.5 1 3 14 6386 5239. 1 5 7 8 8000 6563.1 7 5 llf 44031 3612.6 22^ 4630J 3799. 1 5 2 12 7644 6271. 1 7 4jz 25* 8989| 7374.5 1 1 6* 24 5676 4656.5 1 1 1 16 5272 4325. 1 1 1 26 5282 1433.3 - 0.82039 [ t 1. 1.21895 4 5 35 8827.15 5445.5 18.827 15.445 _ _ -I 1.8827 1.5445 .18827 .15445 The commissioners appointed by the Bri- tish Government for considering the subject of weights and measures, gave in their first report on the 24th June, 1819. The follow, ing is the substance of it. " 1. With respect to the actual magnitude of the standards of length, the commissioners are of opinion, that there is no sufficient rea- son for altering those generally employed, as there is no practical advantage in having a quantity commensurable to any original quan- tity existing, or which may be imagined to exist, in nature, except as affording some little encouragement to its common adoption by neighbouring nations. " 2. The subdivisions of weights and mea- sures at present employed in this country appear to be far more convenient for practical purposes than the decimal scale. The power of expressing a third, a fourth, and a sixth of a foot in inches, without a fraction, is a pe- culiar advantage in the duodecimal scale ; and for the operation of weighing and of mea- suring capacities, the continual division by two renders it practicable to make up any given quantity with the smallest possible num- ber of weights and measures, and is far prefer- able in this respect to any decimal scale. The commissioners therefore recommend, that all the multiples and subdivisions of the standard to be adopted should retain the same relative proportions to each other as are at present in general use. " 3. That the standard yard should be that employed by General Roy in the measure- ment of a base on Hounslow Heath, as a foundation of the great trigonometrical survey. " 4- That in case this standard should be lost or impaired, it shall be declared that the length of a pendulum, vibrating seconds of mean solar time in London, on the level of the sea, and in a vacuum, is 39.1372 inches of the standard scale, and that the length of the French metre, as the 10-millionth part of the quadrantal arc of the meridian, has been found equal to 39-3694 inches. " 5. That 10 ounces troy, or 4800 grains, should be declared equal to the weight of 1 9 cubic inches of distilled water, at the tempe- rature of 50, and that one pound avoirdupois must contain 7000 of these grains. " 6. That the standard ale and corn gal- BAL 198 BAR ton, in his examination before the committee ; and they have been adopted in the national system : " There is one standard of capacity that would be particularly advantageous, because it would bear simple proportions to the mea- sures now in use, so that one of the great inconveniencies arising from change of the standard would be obviated, by the facility of making many necessary computations without reference to tables. If the gallon measure be defined to be Ion should contain exactly ten pounds avoir- dupois of distilled water at 62 Fahr. being nearly equal to 277-3 cubic inches, and agree- ing with the standard pint in the Exchequer, which is found to contain exactly 20 ounces of water. The customary ale gallon contains 282 cubic inches, and the Winchester corn gallon 269, or according to other statutes 272-J cubic inches ; so that no inconvenience can possibly be felt from the introduction of a new gallon of 277.3 inches. The commissioners have not decided upon the propriety of abo- lishing entirely the use of the wine gallon." that which contains lOlbs. of water at 56^ The following simple relations of weight F. ; then, since the cubic foot of water weighs and measure were suggested by Dr. Wollas- 1000 oz. at 56, % pint = 18 oz. =. Y^ Pint = 20 oz. = 34.56 cubic foot = 17.28 inches. Bushel = 80 Ib. = 2211.84 inches. And the simple proportions above alluded to will be found as follows : The gallon of 10 Ib. Also, The pint of 1^ Ib. Bushel of 80 Ib. A cylinder of 18f in diarn. Ditto 18f " The following mode of defining the standards of length, weight, and capacity, is submitted to the committee on weights and measures, as the most distinct answer to their inquiries: r\ A f *r i, f sucn i that a pendulum of 39.13 inches, vibrates seconds in One yard ties, ^ London. Avoir, $ ne ^g d ' f } i* such, that one cubic foot of water at 56, weighs 1000 oz. " lr y J "7Rft"ramsf \ is SUCh ' that 7 grains = * P und ( avoirdu P is )- Cubic Inches. - 276.48 X i = 282.01 = 276.48 X * 230.40 = 34.56 x 3 = 103.68 = 2211.84 X ff 2150.40 X 8 = 2208.93 X 8.0105 282 beer gallon. 231 wine gallon. 103 4 Stirlg. jug. 2 150.42 Winch, bush. Approximate bush. 221.184 new bush. ~ c . . $ may be such as to contain 10 pounds of distilled water at the le gallon, oJ 8 pints, ^ temperature of 56 i Fahr . with g[eSLt convenience." The cubic inch of distilled water at 62, weighed in air under the common circum- stances with brass weights, is equal to 252.456 English grains ; and the cubic decimeter, or actual standard chiliogramme is equal to 15433 English grains. See APPENDIX, TABLE ix. Captain Kater has lately made a small cor- rection on his first determination of the length of the pendulum vibrating seconds in the lati- tude of London. Instead of 39.13860 inches, as given in the Phil. Trans, for 1818, he has made it 39-13929 inches of Sir Geo. Shuck- burgh's standard scale. Mr. Watts, in the 5th number of the Edinburgh Philosophical Journal, makes it = 39-138666 of the above scale, or = 39.1372405 of General Roy's scale, at Captain Rater's temperature of 62 Fahr. and 0-9941 of a metre. BALAS, or BALAIS RUBY. See BALLOON. Receivers of a spherical form are called balloons. BALLOON. See AEROSTATICS. BALSAMS, are vegetable juices, either liquid, or which spontaneously become con- crete, consisting of a substance of a resinous nature, combined with benzoic acid, or which are capable of affording benzoic acid, by being heated alone, or with water. They are inso- luble in water, but readily dissolve in alcohol and ether. The liquid balsams are copaiva, opo-balsam, Peru, styrax, Tolu ; the concrete are benzoin, dragon's blood, and storax ; which see. BALSAM OF SULPHUR. A solution of sulphur in oil. BALDWIN'S PHOSPHORUS. Ig- nited nitrate of lime. BARIUM. The metallic basis of the earth barytes has been called barium by its discoverer, Sir H. Davy. Take pure barytes, BAR 199 BAR make it into a paste with water, and put this on a plate of platinum. Make a cavity in the middle of the barytes, into which a globule of mercury is to be placed. Touch the globule with the negative wire, and the platinum with the positive wire of a voltaic battery of about 100 pairs of plates in good action. In a short time an amalgam will be formed, consisting of mercury and barium. This amalgam must be introduced into a little bent tube, made of glass free from lead, sealed at one end, which being filled with the vapour of naphtha, is then to be hermetically sealed at the other end. Heat must be applied to the recurved end of the tube, where the amalgam lies. The mer- cury will distil over, while the barium will remain. This metal is of a dark grey colour, with a lustre inferior to that of cast-iron. It is fu- sible at a red heat. Its density is superior to that of sulphuric acid ; for though surrounded with globules of gas, it sinks immediately in that liquid. When exposed to air, it instantly becomes covered with a crust of barytes ; and when gently heated in air, burns with a deep red light It effervesces violently in water, converting this liquid into a solution of barytes. Sir H. Davy thinks it probable that barium may be procured by chemical as well as elec- trical decomposition. When chloride of ba- rium, or even the dry earth, ignited to white- ness, is exposed to the vapour of potassium, a dark grey substance is found diffused through the barytes or the chloride, not volatile, which effervesces copiously in water, and possesses a metallic appearance, which disappears in the air. The potassium, by bebg thus transmitted, is converted into potash. From indirect ex- periments Sir H. Davy was inclined to con- sider barytes as composed of 89.7 barium + 10.3 oxygen - 100. This would make the prime equivalent of barium 8.7, and that of barytes 9.7, compared to that of oxygen 1.0; a determination nearly exact. Dr. Clarke of Cambridge, by exposing dry nitrate of barytes on charcoal, to the intense heat of the con* densed hydroxygen flame, observed metallic- looking globules in the midst of the boiling fluid, and the charcoal was found to be studded over with innumerable globules of the most brilliant lustre and whiteness. On letting these globules fall from the charcoal into water, hydrogen was evolved in a continued stream. When the globules are plunged in naphtha, they retain their brilliancy but for a few days. Barium combines with oxygen in two pro- portions, forming, 1st, barytes, and 2d, the deutoxide of barium. Pure barytes is best obtained by igniting, in a covered crucible, the pure crystallized nitrate of barytes. It is procured in the state of hydrate, by adding caustic potash or soda to a solution of the muriate or nitrate. And barytes, slightly coloured with charcoal, may be obtained by strongly igniting the carbonate and charcoal mixed together in fine powder Barytes obtained from the ignited nitrate is of a whitish-grey colour; more caustic than stron- tites, or perhaps even lime. It renders the syrup of violets green, and the infusion of turmeric red. Its specific gravity by Four- croy is 4. When water in small quantity is poured on the dry earth, it slakes like quick- lime, but perhaps with evolution of more heat. When swallowed it acts as a violent poison. It is destitute of smell. When pure barytes is exposed, in a porce- lain tube, at a heat verging on ignition, to a stream of dry oxygen gas, it absorbs the gas rapidly, and passes to the state of deutoxide of barium. But when it is calcined in contact with atmospheric air, we obtain at first this deutoxide and carbonate of barytes ; the for- mer of which passes very slowly into the latter, by absorption of carbonic acid from the atmosphere. The deutoxide of barium is of a greenish- grey colour, it is caustic, renders the syrup of violets green, and is not decomposable by heat or light. The voltaic pile reduces it. Ex- posed at a moderate heat to carbonic acid, it absorbs it, emitting oxygen, and becoming carbonate of barytes. The deutoxide is pro- bably decomposed by sulphuretted hydrogen at ordinary temperatures. Aided by heat, almost all combustible bodies, as well as many metals, decompose it. The action of hydrogen is accompanied with remarkable phenomena. At about 392 F. the absorption of this gas commences ; but at a heat approaching to redness it is exceedingly rapid, attended with luminous jets proceeding from the surface of the deutoxide. Although much water be formed, none of it appears on the sides of the vessel. It is all retained in combination with the protoxide, which in consequence becomes a hydrate, and thus acquires the property of fusing easily. By heating a certain quantity of barytes with an excess of oxygen in a small curved tube standing over mercury, M. The- nard ascertained, that in the deutoxide the quantity of the oxygen is the double of that in the protoxide. Hence the former will con- sist of 8.75 barium -j- 2 oxygen r= 10-75 for its prime equivalent. From the facility with which the protoxide passes into the deutoxide, we may conceive that the former may fre- quently contain a proportion of the latter, to which cause may be ascribed in some degree the discrepancies among chemists, in estimating the equivalent of barytes. Water at 50 F. dissolves one-twentieth of its weight of barytes, and at 212 about one- half of its weight; though M. Thenard, in a table, has stated it at only one-tenth. As the solution cools, hexagonal prisms, terminated at each extremity with a four-sided pyramid, form. These crystals are often attached to one another, so as to imitate the leaves of fern. Sometimes they are deposited in cubes. They contain about 53 per cent, of water, or 20 BAR 200 BAR prime proportions. The supernatant liquid is barytes water, it is colourless, acrid, and caus- tic. It acts powerfully on the vegetable purples and yellows. Exposed to the air, it attracts carbonic acid, and the dissolved ba- rytes is converted into carbonate, which falls down in insoluble crusts. It appears from the experiments of M. Bcrthollet, that heat alone cannot deprive the crystallized hydrate of its water. After exposure to a red heat, when it fuses like potash, a proportion of water remains in combination. This quantity is a prime equivalent =. 1.125, to 9-75 of barytes. The ignited hydrate is a solid of a whitish- grey colour, caustic, and very dense. It fuses at a heat a little under a cherry-red ; is fixed in the fire ; attracts, but slowly, carbonic acid from the atmosphere. It yields carburetted hydrogen and carbonate of barytes when heated along with charcoal, provided this be not in excess. Sulphur combines with barium, when barytes and sulphur are heated together in a crucible. The same compound is more economically obtained by igniting a mixture of sulphate of barytes and charcoal in fine powder. This sulphuret is of a reddish-yellow colour, and when dry without smell. When this sub- stance is put into hot water, a powerful action is manifested. The water is decomposed, and two new products are formed, namely, hydro- sulphuret, and hydroguretted sulphuret of barytes. The first crystallizes as the liquid cools, the second remains dissolved. The hy- drosulphuret is a compound of 9.75 of bavytes with 2.125 sulphuretted hydrogen. Its crys- tals should be quickly separated by filtration, and dried by pressure between the folds of porous paper. They are white scales, have a silky lustre, are soluble in water, and yield a solution having a greenish tinge. Its taste is acrid, sulphurous, and when mixed with the hydroguretted sulphuret, eminently corro- sive. It rapidly attracts oxygen from the at- mosphere, and is converted into the sulphate of barytes. The hydroguretted sulphuret is a compound of 9.75 barytes with 4.125 bisul- phuretted hydrogen: but contaminated with sulphite and hyposulphite in unknown pro- portions. The dry sulphuret consists pro- bably of 2 sulphur + 8.15 barium. The readiest way of obtaining barytes water is to boil the solution of the sulphuret with deutox- ide of copper, which seizes the sulphur, while the hydrogen flies off, and the barytes remains dissolved. Phosphuret of barytes may be easily formed by exposing the constituents together to heat in a glass tube. Their reciprocal action is so intense as to cause ignition. Like phosphuret of lime, it decomposes water, and causes the disengagement of phosphuretted hydrogen gas, which spontaneously inflames with contact of air. When sulphur is made to act on the deutoxidc of barytes, sulphuric acid is formed, which unites to a portion of the earth into & sulphate. The salts of barytes are white, and more or less transparent. All the soluble sulphates cause in the soluble salts of barytes a preci- pitate insoluble in nitric acid. They are all poisonous except the sulphate ; and hence the proper counter-poison is dilute sulphuric acid for the carbonate, and sulphate of soda for the soluble salts of barytes. An account has been given of the most useful of these salts under the respective acids. What remains of any consequence will be found in the table of SALTS. For some interesting facts on the decomposition of the sulphate and carbonate, see ATTRAC- TION. When the object is merely to procure barytes or the sulphuret, form the powdered carbonate or sulphate into a paste with lamp black and coal tar, and subject to strong ignition in a covered crucible. As barytes and strontites are occasionally associated, it be- comes an important problem to separate these two earths, which M. Berzelius operates on the following principle. Fluate of silica and barytes precipitates in crystals almost insoluble. The fluate of silica and strontites is very soluble in excess of the fluo-silicic acid. The mixture of the two earths is to be dissolved in muriatic or acetic acid, then solution of fluo-silicic acid is to be poured in, the br.rytes will precipitate, and its weight is to be determined by that of the precipitate. A very small quantity of sulphuric acid being added to the solution throws down from it the small quantity of barytes that may remain, without acting on the strontites. The liquid is to be filtered, eva- porated to dryness, and the residuum decom- posed by sulphuric acid. The fluate of silica and barytes is made by dissolving barytes in aqueous fluo-silicic acid, till the neutral point be attained. 100 parts of the dry salt afford, by ignition, 62.25 of fluate of barytes ; while 37.75 of silicated fluoric acid flies off; 100 parts of the same salt decomposed by sulphuric acid afford 82.933 of sulphate of barytes. Hence, M. Berzelius states its composition at 3 atoms of fluate of barytes, and 2 atoms of fluate of silica. Ann. de, Chlm. et de Phys. xxvii. 295. See SALT. BARBADOES TAR. SeePETROLiUM. BARILLA, or BARILLOR. The term given in commerce to the impure soda im- ported from Spain and the Levant. It is made by burning to ashes different plants that grow on the sea-shore, chiefly of the genus salsola, and is brought to us in hard porous masses, of a speckled brown colour. Kelp, a still more impure alkali made in this country by burning various sea weeds, is sometimes called British barilla. BAROLITE. Carbonate of barytes. B ARRAS. The resinous incrustation on the wounds made in fir trees. It is also called galipot. BARYSTRONTIANITE, or STROM- BAS 201 BAS NITE. A mineral found in masses of a greyish white colour externally, yellowish white and weakly shining internally. Translucent on the edges ; brittle and soft, sp. grav. 3.703. Effervesces with acids, but does not melt before the blowpipe. It is composed of car- bonate of strontian 68.6 ; sulphate of barytes 27.5 ; carbonate of lime 2. 6 ; oxide of h on 0.1; loss 1.2. Dr. Trulll. It is found in veins, or rather nests, accompanied by galena, at Stromness in Orkney. BARYTE. See HEAVY SPAR. BARYTES. See BARIUM. BARYTO-CALCITE. A mineral found in Cumberland, of a slightly yellowish brown tinge, translucent, with a waxy lustre, and sp. grav. 3.66. It contains cavities which are lined with crystals in oblique rhombic prisms. The external surface is coated with sulphate of barytes. It consists, by Mr. Children's analysis, of about 2 parts, by weight, of carbonate of barytes, and 1 of carbonate of lime, which is a prune equivalent of each. Brooke, Ann. of Phil N. S. viii. 114. BASALT. Occurs in amorphous masses, columnar, amygdaloidal, and vesicular. Its colours are greyish-black, ash-grey, and raven- black. Massive. Dull lustre. Granular structure. Fracture uneven or conchoidal. Concretions ; columnar, globular, or tabular. It is opaque, yields to the knife, but not easily frangible. Streak light ash-grey. Sp. gravity 3. Melts into a black glass. It is found in beds and veins in granite and mica slate, the old red sandstone, limestone, and coal formations. It is distributed over the whole world; but nowhere is met with in greater variety than in Scotland. The German basalt is supposed to be a watery deposit ; and that of France to be of volcanic origin. The most remarkable is the columnar ba- saltes, which forms immense masses, composed of columns thirty, forty, or more feet in height, and of enormous thickness. Nay, those at Fan-head are two hundred and fifty feet high. These constitute some of the most astonishing scenes in nature, for the immensity and regu- larity of their parts. The coast of Antrim in Ireland, for the space of three miles in length, exhibits a very magnificent variety of columnar cliffs : and the Giant's Causeway consists of a point of that coast formed of similar columns, and projecting into the sea upon a descent for several hundred feet. These columns are, for the most part, hexagonal, and fit very accu- rately together ; but most frequently not ad- herent to each other, though water cannot penetrate between them. And the basaltic appearances on the Hebrides Islands on the coast of Scotland, as described by Sir Joseph Banks, who visited them in 1772, are upon a scale very striking for their vastness and variety. An extensive field of inquiry is here offered to the geological philosopher, in his attempts to ascertain the alterations to which the globe has been subjected. The inquiries of the chemist equally co-operate in these researches, and tend likewise to show to what useful pur- poses this and other substances may be applied. Bergmann found that the component parts of various specimens of basal tes were, at a me- dium, 52 parts silex, 15 alumina, 8 carbonate of lime, and 25 iron. The differences seem, however, to be considerable ; for Faujas de St. Fond gives these proportions: 46 silex, 30 alumina, 10 lime, 6 magnesia, and 8 iron. The amorphous basaltes, known by the name of rowley rag, the ferrilite of Kirwan, of the spe- cific gravity of 2.748, afforded Dr. Withering 47.5 of silex, 32.5 of alumina, and 20 of iron, at a very low degree of oxidation probably. Dr. Kennedy, in his analysis of the basaltes of Staffa, gives the following as its component parts : silex 48, alumina 16, oxide of iron 16, lime 9, soda 4, muriatic acid 1, water and volatile parts 5. Klaproth gives for the analysis of the prismatic basaltes of Hasenberg : silex 44.5, alumina 16-75, oxide of iron 20, lime 9.5, magnesia 2.25, oxide of manganese 0.12, soda 2.60, water 2. On a subsequent analysis, with a view to detect the existence of muriatic acid, he found slight indications of it, but it was in an extremely minute proportion. Sir James Hall and Mr. Gregory Watt have both proved, by well conducted experiments, that basalt, when fused into a perfect glass, will resume the stony structure by slow cool- ing; and hence have endeavoured to show, that the earthy structure affords no argument against the igneous formation of basalt in the terrestrial globe. Basaltes, when calcined and pulverized, is said to be a good substitute for puzzolana in the composition of mortar, giving it the pro- perty of hardening under water. Wine bottles have likewise been manufactured with it ; but there appears to be some nicety requisite hi the management to ensure success. BASALTIC HORNBLENDE. Itusually occurs in opaque six-sided single crystals, which sometimes act on the magnetic needle. It is imbedded in basalt or wacke. Colour velvet- black. Lustre vitreous. Scratches glass. Sp. gr. 3.25. Fuses with difficulty into a black glass. It consists of 47 silica, 26 alumina, 8 lime, 2 magnesia, 15 iron, and 0.5 water. It is found in the basalt of Arthur's Seat, in that of Fifeshire, and in the Isles of Mull, Canna, Eigg, and Sky. It is found also in the basaltic and floetz trap rocks of England, Ireland, Saxony, Bohemia, Silesia, Bavaria, Hungary, Spain, Italy, and France. BASANITE, See FLINTY SLATE. BASE or BASIS. A chemical term usually applied to alkalis, earths, and metallic oxides, in their relations to the acids and salts. It is sometimes also applied to the particular con- stituents of an acid or oxide, on the supposition that the substance combined with the oxygen, BDE 202 BEE &c. is the basis of the compound to which it owes its particular qualities. This notion seems unphilosophieal, as these qualities depend as much on the state of combination as on the nature of the constituent. BASSORINE. This substance is extracted from the gum resins which contain it, by treating them successively with water, alcohol, and ether. Bassorine being insoluble in these liquids, remains mixed merely with the woody particles, from which it is easy to separate it, by repeated washings and decantations ; be- cause one of its characteristic properties is to swell extremely in the water and to become very buoyant. This substance swells up in cold as well as boiling water, without any of its parts dissolving. It is soluble however almost completely by the aid of heat, in water sharpened with nitric or muriatic acid. If after concentrating with a gentle heat the nitric solution, we add highly rectified alcohol, there results a white precipitate, flocculent and bulky, which, washed with much alcohol and dried, does not form, at the utmost, the tenth of the quantity of bassorine employed, and which presents all the properties of gum-arabic. Vau- qnelin, Bulletin de Pharmacie, iii. 56. BATH. The heat communicated from bodies in combustion must necessarily vary according to circumstances ; and this variation not only influences the results of operations, but in many instances endangers the vessels, especially if they be made of glass. Among the several methods of obviating this incon- venience, one of the most usual consists in interposing a quantity of sand, or other matter, between the fire and the vessel intended to be heated. The sand bath and the water bath are most commonly used ; the latter of which was called Balneum Mariae by the elder chemist?. A bath of steam may, in some instances, be found preferable to the water bath. Some chemists have proposed baths of melted lead, of tin, and of other fusible substances. These may perhaps be found advantageous in a few peculiar operations, in which the intelli- gent operator must indeed be left to his own sagacity. A considerably greater heat may be given to the water bath by dissolving various salts in it. Thus a saturated solution of common salt boils at 2250.3. or 13.3 Fahr. above the boiling point of water. By using solution of muriate of lime, a bath of any tempe- rature from 212 to 252 may be conveniently obtained. BDELLIUM. A gum resin, supposed to be of African origin. The best bdellium is of a yellowish-brown, or dark-brown colour, ac- cording to its age ; unctuous to the touch, brittle, but soon softening, and growing tough betwixt the fingers; in some degree transparent, not unlike myrrh ; of a bitterish taste, and a moderately strong smell. It does not easily take flame, and, when set on fire, soon goes out. In burning it sputters a little, owing to its aqueous humidity. Its sp. grav. is 1.371. Alcohol dissolves about three-fifths of bdel- lium, leaving a mixture of gum and cerasin. Its constituents, according to Pelletier, are 59 resin, 9.2 gum, 30.6 cerasin, 1.2 volatile oil and loss. BEAN. The seed of the vinafaba, a small esculent bean, which becomes black as it ripens, has been analyzed by Einholf. He found 3840 parts to consist of 600 volatile matter, 386 skins, 610 fibrous starchy matter, 1312 starch, 417 vegeto-animal matter, 31 albumen, 136* extractive, soluble in alcohol, 177 gummy matter, 37 earthy phosphate, 133^ loss. Fourcroy and Vauquelin found its incinerated ashes to contain the phosphates of lime, mag- nesia, potash, and iron, with uncombined potash. They found no sugar in this bean. Kidney beans, the seeds of the pliaseolm vul- garis, yielded to Einholf 288 skins, 425 fibrous starchy matter, 1 380 starch, 799 vegeto-animal matter, not quite free from starch, 131 ex- tractive, 52 albumen, with some vegeto-animal matter, 744 mucilage, and 21 loss in 3840. BEE. The venom of the bee, according to Fontana, bears a close resemblance to that of the viper. It is contained in a small vesicle, and has a hot and acrid taste, like that of the scorpion. BEER is the wine of grain. Malt is usually made of barley. The grain is steeped for two or three days in water, until it swells, becomes somewhat tender, and tinges the water of a bright reddish-brown colour. The water being then drained away, the barley is spread about two feet thick upon a floor, where it heats spontaneously, and begins to grow, by first shooting out the radicle. In this state the germination is stopped by spreading it thinner, and turning it over for two days; after which it is again made into a heap, and suffered to become sensibly hot, which usually happens in little more than a day. Lastly, it is conveyed to the kiln, where, by a gradual and low heat, it is rendered dry and crisp. This is malt ; and its qualities differ accord- ing as it is more or less soaked, drained, ger- minated, dried, and baked. In this, as in other manufactories, the intelligent operators often make a mystery of their processes from views of profit ; and others pretend to peculiar secrets who really possess none. Indian corn, and probably all large grain, requires to be suffered to grow into the blade, as well as root, before it is fit to be made into malt. For this purpose it is buried about two or three inches deep in the ground, and covered with loose earth ; and in ten or twelve days it springs up. In this state it is taken up and washed, or fanned, to clear it from its dirt ; and then dried in the kiln for use. Barley, by being converted into malt, be- comes one-fifth lighter, or 20 per cent. ; 12 of which are owing to kiln drying, 1.5 are BEE 203 BEE carried off by the steep. water, 3 dissipated on the floor, 3 lost in cleaning the roots, and 0-5 waste or loss. The degree of heat to which the malt is exposed in this process, gradually changes its colour from very pale to actual blackness, as it simply dries it, or converts it to charcoal. The colour of the malt not only affects the colour of the liquor brewed from it, but, in consequence of the chemical operation, of the heat applied, on the principles that are de- veloped in the grain during the process of malting, materially alters the quality of the beer, especially with regard to the properties of becoming fit for drinking and growing fine. Beer is made from malt previously ground, or cut to pieces by a mill. This is placed in a tun, or tub with a false bottom ; hot water is poured upon it, and the whole stirred about with a proper instrument. The temperature of the water in this operation, called Mashing, must not be equal to boiling ; for, in that case, the malt would be converted into a paste, from which the impregnated water could not be separated. This is called Setting. After the infusion has remained for some time upon the malt, it is drawn off, and is then distinguished by the name of Sweet Wort. By one or more subsequent infusions of water, a quantity of weaker wort is made, which is either added to the foregoing, or kept apart, according to the intention of the operator. The wort is then boiled with hops, which give it an aromatic bitter taste, and are supposed to render it less liable to be spoiled in keeping ; after which it is cooled in shallow vessels, and suffered to ferment, with the addition of a proper quan- tity of yeast. The fermented liquor is beer ; and differs greatly in its quality, according to the nature of the grain, the malting, the mash- ing, the quantity and kind of the hops and the yeast, the purity or admixtures of the water made use of, the temperature and vicis- situdes of the weather, &c. Beside the various qualities of malt liquors of a similar kind, there are certain leading features by which they are distinguished, and classed under different names, and to produce which, different modes of management must be pursued. The principal distinctions are into beer, properly so called ; ale ; table or small beer ; and porter, which is commonly termed beer in London. Beer is a strong, fine, and thin liquor ; the greater part of the mucilage having been separated by boiling the wort longer than for ale, and carrying the fer- mentation farther, so as to convert the saccha- rine matter into alcohol. Ale is of a more sirupy consistence, and sweeter taste ; more of the mucilage being retained in it, and the fer- mentation not having been carried so far as to decompose all the sugar. Small beer, as its name implies, is a weaker liquor ; and is made cither by adding a large portion of water to the malt, or by mashing with a fresh quantity of water what is left after the beer or ale wort is drawn off. Porter was probably made ori- ginally from very high dried malt ; but it is said, that its peculiar flavour cannot be im- parted by malt and hops alone. Mr Brande obtained the following quan- tities of alcohol from 100 parts of different species of beers. Burton ale, 8- 88, Edinburgh ale, 6.2, Dorchester ale, 5.56; the average being = 6.87. Brown stout, 6.8, London porter (average) 4.2, London small beer (ave- rage) 1.28. As long ago as the reign of Queen Anne, brewers were forbid to mix sugar, honey, Guinea pepper, essentiabina, cocculus indicus, or any other unwholesome ingredient, in beer, under a certain penalty ; from which we may infer, that such at least was the practice of some ; and writers, who profess to discuss the secrets of the trade, mention most of these, and some other articles, as essentially necessary. The essentia bina is sugar boiled down to a dark colour, and empyreumatic flavour. Broom tops, wormwood, and other bitter plants, were formerly used to render beer fit for keeping, before hops were introduced into this country ; but are now prohibited to be used in beer made for sale. By the present law of this country, nothing is allowed to enter into the composition of beer, except malt and hops. Quassia and wormwood are often fraudulently introduced ; both of which are easily discoverable by their nauseous bitter taste. They form a beer which does not preserve so well as hop beer. Sul- phate of iron, alum, and salt, are often added by the publicans, under the name of leer- heading^ to impart a frothing property to beer, when it is poured out of one vessel into another. Molasses and extract of gentian root are added with the same view. Capsicum, grains of paradise, ginger root, coriander seed, and orange peel, are also employed to give pun- gency and flavour to weak or bad beer. The following is a list of some of the unlawful sub- stances seized at different breweries, and brewers' druggists' laboratories, in London, as copied from the minutes of the committee of the House of Commons. Cocculus indicus multum (an extract of the cocculus), colouring, honey, hartshorn shavings, Spanish juice, orange powder, ginger, grains of paradise, quassia, liquorice, caraway seeds, copperas, capsicum, mixed drugs. Sulphuric acid is very frequently added to bring beer forward, or make it hard, giving new beer instantly the taste of what is 18 months old. According to Mr. Accum, the present entire beer of the London brewer is composed of all the waste and spoiled beer of the publicans, the bottoms of butts, the leavings of the pots, the drippings of the machines for drawing the beer, the remnants of beer that lay in the leaden pipes of the brewery, with a portion of brown stout, bottling beer, and mild beer. He says that BEN 204 BER opium, tobacco, nux vomica, and extract of poppies, have been likewise used to adulterate beer. For an account of the poisonous qua- lities of the cocculusindicus, see PICROTOXIA ; and for those of nux vomica, see STRYCHNIA. By evaporating a portion of beer to dryness, and igniting the residuum with chlorate of potash, the iron of the copperas will be pro- cured in an insoluble oxide. Muriate of ba- rytes will throw down an abundant precipitate from beer contaminated with sulphuric acid or copperas ; which precipitate may be col- lected, dried, and ignited. It will be insoluble in nitric acid. Beer appears to have been of ancient use, as Tacitus mentions it among the Germans, and has been usually supposed to have been peculiar to the northern nations : but the ancient Egyptians, whose country was not adapted to the culture of the grape, had also contrived this substitute for wine; and Mr. Park has found the art of making malt, and brewing from it very good beer, among the negroes in the interior parts of Africa. BEET. The root of the beet affords a considerable quantity of sugar, and has lately been cultivated for the purpose of extracting it to some extent in Germany. See SUGAR. It is likewise said, that if beet roots be dried in the same manner as malt, after the greater part of their juice is pressed out, very good beer may be made from them. BELLADONNA, the plant called in English Deadly Nightshade, from which the alkaline matter ATROPIA is extracted. M. Runge. says, that the narcotic principle of belladonna is destroyed, or so changed, by alkaline solutions, as to lose its distinguishing property of causing dilatation of the pupil. This takes place when the solutions are weak or even with lime water ; so that this principle cannot be obtained by the usual process through the intervention of alkalis. Magnesia exerts no action of this kind ; and it should be used as a hydrate uncalcined. It should be thrown down from sulphate of magnesia by potash not in sufficient quantity to decompose the whole salt, the mixture added to the aqueous infusion of belladonna, and the whole evapo- rated by a brisk fire to dryness ; the residuum when dried and pulverized, is to be treated with highly rectified alcohol. The clear yellow solution being evaporated spontaneously, yields a crystalline mass, which slightly blues red- dened litmus paper, dissolves- in water, and produces extreme dilatation of the pupil. Its salts have also the sameeffect. Ann. de Chimie, xxvii. 32. BELLMETAL. See COPPER. BELLMETAL ORE. See ORES or TIN. BEN (OIL OF). This is obtained from the ben nut by simple pressure. It is re- markable for its not growing rancid in keeping, or at lea^t not until it has stood for a number of years ; and on this account it is used in extracting the aromatic principle of such odo- riferous flowers as yield little or no essential oil in distillation. BENZOIC ACID. See ACID (BEN- ZOIC). BENZOIN, or BENJAMIN. The tree which produces benzoin is a native of the East Indies, particularly of the island Siam and Sumatra*. The juice exudes from inci- sions, in the form of a thick white balsam. If collected as soon as it has grown somewhat solid, it proves internally white like almond, and hence it is called Benzoe Amygdaloides : if suffered to lie long exposed to the sun and air, it changes more and more to a brownish, and at last to a quite reddish-brown colour. This resin is moderately hard and brittle, and yields an agreeable smell when rubbed or warmed. When chewed, it impresses a slight sweetness on the palate. It is totally soluble in alcohol; from which, like other resins, it may be precipitated by the addition of water. Its specific gravity is 1.092. The white opaque fluid thus obtained has been called Lac Virginale ; and is still sold, with other fragrant additions, by perfumers, as a cosmetic. Boiling water separates the peculiar acid of benzoin. The products Mr. Brande obtained by dis- tillation were, from 100 grains, benzoic acid 9 grains, acidulated water 5.5, butyraceous and empyreumatic oil 60, brittle coal 22, and a mixture of carburetted hydrogen and carbo- nic acid gas, computed at 3.5. On treating the empyreumatic oil with water, however, 5 grains more of acid were extracted, making 14 in the whole. From 1500 grains of benzoin, Bucholz ob- tained 1250 of resin, 187 benzoic acid, 25 of a substance similar to balsam of Peru, 8 of an aromatic substance soluble in water and alcohol, and 30 of woody fibres and impuri- ties. Ether, sulphuric, and acetic acids, dissolve benzoin ; so do solutions of potash and soda. Nitric acid acts violently on it, and a portion of artificial tannin is formed. Ammonia dis- solves it sparingly. BERGMANNITE. A massive mineral of a greenish, greyish- white, or reddish colour. Lustre intermediate between pearly and re- sinous. Fracture fibrous, passing into fine grained, uneven. Slightly translucent on the edges. Scratches felspar. Fuses into a trans- parent glass, or a semitransparent enamel. It is found at Frederickswarn in Norway, in quartz and in felspar. BERYL. This precious mineral is most commonly green, of various shades, passing * Consult the Philosophical Transactions, vol. Ixxvii. p. 307- for a botanical description and drawing of the tree, by Dryander. BEZ 205 BIL into honey-yellow, and sky-blue. It is crys- tallized in hexahedral prisms deeply striated longitudinally, or in 6 or 12 sided prisms, terminated by a 6 sided pyramid, whose sum- mit is replaced. It is harder than the eme- rald, but more readily yields to cleavage. Its sp. grav. is 2.7. Its lustre is vitreous. It is transparent, and sometimes only translucent. It consists by Vauquelin of 68 silica, 15 alu- mina, 14 glucina, 1 oxide of iron, 2 lime. Bsrzelius found in it a trace of oxide of tanta- lum. It occurs in veins traversing granite in Daouria ; in the Altaic chain in Siberia ; near Limoges in France ; in Saxony ; Brazil ; at Kinlock Raimoch, and Cairngorm, Aberdeen- shire, Scotland; above Dundrum, in the county of Dublin, and near Cronebane, county of Wicklow, in Ireland. It differs from eme- rald in hardness and colour. It has been called aqua marine, and greenish-yellow eme- rald. It is electric by friction, and not by heat. BEUDANTITE. A new mineral occur- ring in small crystals closely aggregated, being slightly obtuse rhombohedrons with the sum- mits truncated. Colour black; lustre resi- nous ; in thin fragments translucent, and of a deep brown colour. Primitive form, an ob- tuse rhomboid of 92 30'. Hardness greater than that of fluate of lime. Powder greenish- grey. It comes from Hohrhausen on the Rhine. The only substances that Dr. Wol- laston could detect in it were oxide of lead and oxide of iron. Annals of Phil. xi. 196. BEZOAR. This name, which is derived from a Persian word implying an antidote to poison, was given to a concretion found in the stomach of an animal of the goat kind, which was once very highly valued for this imaginary quality, and has thence been extended to all concretions found in animals. These are of eight kinds, according to Four- croy, Vauquelin, and Berthollet. 1. Super- phosphate of lime, which forms concretions in the intestines of many mammalia. 2. Phos- phate of magnesia, semitransparent and yel- lowish, and of sp. grav. 2.160. 3. Phosphate of ammonia and magnesia. A concretion of a grey or brown colour, composed of radiations from a centre. It is found in the intestines of herbiverous animals, the elephant, horse, &c. 4. Biliary, colour reddish-brown, found fre- quently in the intestines and gall bladder of oxen, and used by painters for an orange-yel- low pigment. It is inspissated bile. 5. Re- sinous. The oriental bezoars, procured from unknown animals, belong to this class of con- cretions. They consist of concentric layers, are fusible, combustible, smooth, soft, and finely polished. They are composed of bile and resin. 6. Fungous, consisting of pieces of the boletus igniarius, swallowed by the ani- mal. 7. Hairy. 8. Ligniform. Three be- zoars sent to Bonaparte by the king of Persia were found by Berthollet to be nothing but woody fibre agglomerated. BIHYDROGURET OF CARBON. See CARBURETTED HYDROGEN. BIHYDROGURET OF PHOSPHO- RUS. See PHOSPHURETTED HYDRO- GEX. BILDSTEIN, AGALMATOLITE, or FIGURESTONE. A massive mineral, with sometimes an imperfectly slaty structure. Co- lour grey, brown, flesh-red, and sometimes spotted, or with blue veins. It is translucent on the edges, unctuous to the touch, and yields to the nail. Sp. grav. 2,8. It is composed of 56 silica, 29 alumina, 7 potash, 2 lime, 1 oxide of iron, and 5 water, by Vauquelin. Klaproth found in a specimen from China, 54.5 silica, 34 alumina, 6.25 potash, 0-75 oxide of iron, and 4 water. It fuses into a transparent glass. M. Brogniart calls it stea- tite pagodite from its coming from China cut into grotesque figures. It wants the magnesia, which is a constant ingredient of steatites. It is found at Naygag in Transylvania,- and Gly- derbach in Wales. BILE. A bitter liquid, of a yellowish or greenish-yellow colour, more or less viscid, of a sp. gravity greater than that of water, com- mon to a great number of animals, the peculiar secretion of their liver. It is the prevailing opinion of physiologists, that the bile is sepa- rated from the venous, and not, like the other secretions, from the arterial blood. The veins which receive the blood distributed to the ab- dominal viscera, unite into a large trunk called the -vena porta, which divides into two branches, that penetrate into the liver, and divi'le into innumerable ramifications. The last of these terminate partly in the biliary ducts, and partly in the hepatic veins, which restore to the circulation the blood not needed for the formation of bile. This liquid passes directly into the duodenum by the ductus cho- ledocus, when the animal has no gall bladder; but when it has one, as more frequently hap- pens, the bile flows back into it by the cystic duct, and remaining there for a longer or shorter time, experiences remarkable altera- tions. Its principal use seems to be, to pro- mote the duodenal digestion, in concert with the pancreatic juice. Boerhaave, by an extravagant error, regarded the bile as one of the most putrescible fluids ; and hence originated many hypothetical and absurd theories on diseases and their treat- ment. We shall follow the arrangement of M. Thenard, in a subject which owes to him its chief illustration. Ox bile is usually of a greenish-yellow colour, rarely a deep green. By its colour it changes the blue of turnsole and violet to a reddish-yellow. At once very bitter, and slightly sweet, its taste is scarcely supportable. Its smell, though feeble, is easy to recognize, BIL 206 BIS and approaches somewhat to the nauseous odour of certain fatty matters when they are heated. Its specific gravity varies very little. It is about 1.026 at 43 F. It is sometimes limpid, and at others disturbed with a yellow matter, from which it may be easily separated by water : its consistence varies from that of a thin mucilage, to viscidity. Cadet regarded it as a kind of soap. This opinion was first refuted by M. Thenard. According to this able chemist, 800 parts of ox bile are com- posed of 700 water, 15 resinous matter, 69 picromel, about 4 of a yellow matter, 4 of soda, 2 phosphate of soda, 3.5 muriates of soda and potash, 0.8 sulphate of soda, 1.2 phos- phate of lime, and a trace of oxide of iron. "When distilled to dryness, it leaves from l-8th to l-9th of solid matter, which, urged with a higher heat, is resolved into the usual igneous products of animal analysis ; only with more oil and less carbonate of ammonia. Exposed for some time in an open vessel, the bile gradually corrupts, and lets fall a small quantity of a yellowish matter ; then its mucilage decomposes. Thus the putrefactive process is very inactive, and the odour it ex- hales is not insupportable, but in some cases has been thought to resemble that of musk. Water and alcohol combine in all proportions with bile. When a very little, acid is poured into bile, it becomes slightly turbid, and red- dens litmus ; when more is added, the precipi- tate augments, particularly if sulphuric acid be employed. It is formed of a yellow animal matter, with very little resin. Potash and soda increase the thinness and transparency of bile. Acetate of lead precipitates the yel- low matter, and the sulphuric and phosphoric acids of the bile. The solution of the suba- cetate precipitates not only these bodies, but also the picromel and the muriatic acid, all combined with the oxide of lead. The acetic acid remains in the liquid united to the soda. The greater number of fatty substances are capable of being dissolved by bile. This pro- perty, which made it be considered a soap, is owing to the soda, and to the triple compound of soda, resin, and picromel. Scourers some- times prefer it to soap, for cleansing woollen. The bile of the calf, the dog, and the sheep, are similar to that of the ox. The bile of the sow contains no picromel. It is merely a soda- resinous soap. Human bile is peculiar. It varies in colour, sometimes being green, gene- rally yellowish-brown, occasionally almost colourless. Its taste is not very bitter. In the gall bladder it is seldom limpid, contain- ing often, like that of the ox, a certain quan- tity of yellow matter in suspension. At times this is in such quantity, as to render the bile somewhat grumous. Filtered and boiled, it becomes very turbid, and diffuses the odour of white of egg. When evaporated to dryness, there results a brown extract, equal in weight to 1-1 Uh of the bile. By calcination we ob- tain the same salts as from ox bile. All the acids decompose human bile, and occasion an abundant precipitate of albumen and resin, which are easily separable by alco- hol. One part of nitric acid, sp. grav. 1.210, saturates 100 of bile. On pouring into it a solution of sugar of lead, it is changed into a liquid of a light-yellow colour, in which no picromel can be fouud, and which contains only acetate of soda and some traces of animal matter. Human bile appears hence to be formed, by Thenard, in 1100 parts; of 1000 water ; from 2 to 1 yellow insoluble matter ; 42 albumen ; 41 resin ; 5.6 soda ; and 45 phos- phates of soda and lime, sulphate of soda, mu- riate of soda, and oxide of iron. But by Ber- zelius, its constituents are in 1000 parts ; 908.4 water; 80 picromel ; 3 albumen; 4.1 soda; 0.1 phosphate of lime; 3.4 common salt ; and 1 phosphate of soda, with some phosphate of lime. BIRDLIME. The best birdlime is made of the middle bark of the holly, boiled seven or eight hours in water, till it is soft and tender; then laid in heaps in pits in the ground and covered with stones, the water being previously drained from it ; and in this state left for two or three weeks to ferment, till it is reduced to a kind of mucilage. This being taken from the pit is pounded in a mor- tar to a paste, washed in river water, and kneaded, till it is freed from extraneous mat- ters. In this state it is left four or five days in earthen vessels, to ferment and purify it- self, when it is fit for use. It may likewise be obtained from the mistle- toe, the viburnum lantana, young shoots of elder, and other vegetable substances. It is sometimes adulterated with turpentine, oil, vinegar, and other matters. Good birdlime is of a greenish colour, and sour flavour; gluey, stringy, and tenacious; and in smell resembling linseed oil. By ex- posure to the air it becomes dry and brittle, so that it may be powdered ; but its viscidity is restored by wetting it. It reddens tincture of litmus. Exposed to a gentle heat it lique- fies slightly, swells in bubbles, becomes gru- mous, emits a smell resembling that of animal oils, grows brown, but recovers its properties on cooling, if not heated too much. With a greater heat it burns, giving out a brisk flame and much smoke. The residuum contains sulphate and muriate of potash, carbonate of lime and alumina, with a small portion of iron. BISMUTH is a metal of a yellowish or reddish-white colour, little subject to change in the air. It is somewhat harder than lead, and is scarcely, if at all malleable ; being easily broken, and even reduced to powder, by the hammer. The internal face, or place of fracture, exhibits large shining plates, dis- posed in a variety of positions ; thin pieces BIS 207 BIS are considerably sonorous. At a temperature of 480 Fahrenheit, it melts, and its surface becomes covered with a greenish-grey or brown oxide. A stronger heat ignites it, and causes it to burn with a small blue flame; at the same time that a yellowish oxide, known by the name of flowers of bismuth, is driven up. This oxide appears to rise in consequence of the combustion ; for it is very fixed, and runs into a greenish glass when exposed to heat alone. This oxide consists of 100 metal + 11.275 oxygen, whence its prime equivalent will be 9.87, and that of the metal itself 8.87- The specific gravity of the metal is 9-85. Bismuth urged by a strong heat in a closed vessel, sublimes entire, and crystallizes very distinctly when gradually cooled. Sulphuric acid has a slight action upon bis- muth, when it is concentrated and boiling. Sulphurous acid gas is exhaled, and part of the bismuth is converted into a white oxide. A small portion combines with the sulphuric acid, and affords a deliquescent salt in the form of small needles. Nitric acid dissolves bismuth with the great- est rapidity and violence; at the same time that much heat is extricated, and a large quantity of nitric oxide escapes. The so- lution, when saturated, affords crystals as it cools ; the salt detonates weakly, and leaves a yellow oxide behind, which effloresces in the air. Upon dissolving this salt in water, it renders that fluid of a milky white, and lets fall an oxide of the same colour. The nitric solution of bismuth exhibits the same property when diluted with water, most of the metal falling down in the form of a white oxide, called magistery of bismuth. This precipitation of the nitric solution, by the addition of water, is the criterion by which bismuth is distinguished from most other metals. The magistery> or oxide, is a very white and subtile powder ; when prepared by the addition of a large quantity of water, it is used as a paint for the complexion, and is thought gradually to impair the skin. The liberal use of any paint for the skin seems indeed likely to do this ; but there is reason to suspect, from the resemblance between the general properties of lead and bismuth, that the oxide of this metal may be attended with effects similar to those which the oxides of lead are known to produce. If a small por- tion of muriatic acid be mixed with the nitric, and the precipitated oxide be washed with but a small quantity of cold water, it will appear in minute scales of a pearly lustre, consti- tuting the pearl powder of perfumers. These paints are liable to be turned black by sul- phuretted hydrogen gas. Muriatic acid does not readily act upon bis- muth. When bismuth is exposed to chlorine gas it takes fire, and is converted into a chloride, which, formerly prepared by heating the metal with corrosive sublimate, was called butter of bismuth. The chloride is of a greyish- white colour, a granular texture, and is opaque. It is fixed at a red heat. According to Dr. John Davy, it is composed of 33.6 chlorine, + 66.4 bismuth, 100; or in equivalent numbers, of 4-5 chlorine, + 8.87 bismuth, = 13.37. When iodine and bismuth are heated toge- ther, they readily form an iodide of an orange- yellow colour, insoluble in water, but easily dissolved in potash ley. Alkalis likewise precipitate its oxide ; but not of so beautiful a white colour as that afforded by the affusion of pure water. The gallic acid precipitates bismuth of a greenish-yellow, as ferroprussiate of potash does of a yellowish colour. There appears to be two sulphurets, the first a compound of 100 bismuth to 22.34 sulphur ; the second of 100 to 46.5 : the second is a bisulphuret. This metal unites with most metallic sub- stances, and renders them in general more fusible. When calcined with the imperfect metals, its glass dissolves them, and produces the same effect as lead in cupellation; in which process it is even said to be preferable to lead. Bismuth is used in the composition of pew- ter, in the fabrication of printers' types, and in various other metallic mixtures. With an equal weight of lead, it forms a brilliant white alloy, much harder than lead, and more mal- leable than bismuth, though not ductile ; and if the proportion of lead be increased, it is ren- dered still more malleable. Eight parts of bismuth, five of lead, and three of tin, con- stitute the fusible metal, sometimes called Newton's, from its discoverer, which melts at the heat of boiling water, and may be fused over a candle in a piece of stiff paper without burning the paper. One part of bismuth, with five of lead, and three of tin, forms pewterer's solder. It forms the basis of a sympathetic ink. The oxide of bismuth precipitated by potash from nitric acid has been recommended in spasmodic disorders of the stomach, and given in doses of four grains, four times a-day. A writer in the Jena Journal says he has known the dose carried gradually to one scruple without injury. Bismuth is easily separable, in the dry way, from its ores, on account of its great fusibility. It is usual, in the processes at large, to throw the bismuth ore into a fire of wood ; beneath which a hole is made in the ground to receive the metal, and defend it from oxidation. The same process may be imitated in the small way, in the examination of the ores of this metal ; nothing more being necessary, than to expose it to a moderate heat in a crucible, with a quantity of reducing flux ; taking care, BIT 208 BLA at the same time, to perform the operation as speedily as possible, that the bismuth may be neither oxidized nor volatilized. See SALT. BISTRE. A brown pigment, consisting of the finer parts of wood soot, separated from the grosser by washing. The soot of the beech is said to make the best. BISULPHATE. See SULPHATE, under ACID (SULPHURIC). BITTER PRINCIPLE, of which there are several varieties. When nitric acid is digested on silk, indigo, or white willow, a substance of a deep yellow colour, and an intensely bitter taste, is formed. It dyes a permanent yellow. It crystallizes in oblong plates, and saturates alkalis, like an acid, producing crystallizable salts. That with potash is in yellow prisms. They are bitter, permanent in the air, and less soluble than the insulated bitter principle. On hot charcoal they deflagrate. When struck smartly on an anvil, they detonate with much violence, and with emission of a purple light. Ammonia deepens the colour of the bitter principle solu- tion, and forms a salt in yellow spiculae. It unites also with the alkaline earths and metal- lic oxides. M. Chevreul considers it a com- pound of nitric acid, with a peculiar substance of an oily nature. Quassia, cocculus indicus, daphne Alpina, coffee, squills, colocynth, and bryony, as well as many other medicinal plants, yield bitter principles, peculiarly modified. BITTERN. The mother water which re- mains after the crystallization of common salt in sea water, or the water of salt springs. It abounds with sulphate and muriate of mag- nesia, to which its bitterness is owing. See WATER (SEA). BITTERSPAR, or RHOMBSPAR. This mineral crystallizes in rhomboids, which were confounded with those of calcareous spar, till Dr. Wollaston applied his admirable re- flective goniometer, and proved the peculiarity of the angles in bitterspar, which are 106 15' and 73 45'. Its colour is greyish or yellow, with a somewhat pearly lustre. It is brittle, semitransparent, splendent, and harder than calcareous spar. Fracture straight, foliated, with a threefold cleavage. Its sp. gr. is 2.88. It consists of from 68 to 73 carbonate of lime, 25 carbonate of magnesia, and 2 oxide of man- ganese. It is usually embedded in serpentine, chlorite, or steatite ; and is found in the Tyrol, Sabiburg, and Dauphiny. In Scotland, on the borders of Loch Lomond in chlorite slate, and near Newton Stewart, in Galloway ; as also in the Isle of Man. It bears the same relation to dolomite and magnesian limestone, that cal- careous spar does to common limestone.* BITUMEN. This term includes a con- siderable range of inflammable mineral sub- stances, burning with flame in the open air. They are of different consistency, from a thin fluid to a solid ; but the solids are for the most part liquefiable at a moderate heat. The fluid are, 1. Naphtha ; a fine, white, thin, fragrant, colourless oil, which issues out of white, yel- low, or black clays in Persia and Media. This is highly inflammable, and is decomposed by distillation. It dissolves resins, and the essen- tial oils of thyme and lavender ; but is not it- self soluble either in alcohol or ether. It is the lightest of all the dense fluids, its specific gravity being 0-708. 2. Petroleum, which is a yellow, reddish, brown, greenish, or black- ish oil, found dropping from rocks, or issuing from the earth, in the duchy of Mcdena, and in various other parts of Europe and Asia. This likewise is insoluble in alcohol, and seems to consist of naphtha, thickened by ex- posure to the atmosphere. It contains a por- tion of the succinic acid. 3. Barbadoes tar, which is a viscid, brown, or black inflamma- ble substance, insoluble in alcohol, and con- taining the succinic acid. This appears to be the mineral oil in its third state of alteration. The solid are, 1. Asphaltum, mineral pitch, of which there are three varieties ; the cohe- sive ; the semi -compact, maltha ; the compact, or asphaltum. These are smooth, more or less hard or brittle, inflammable substances, which melt easily, and burn without leaving any or but little ashes, if they be pure. They are slightly and partially acted on by alcohol and ether. 2. Mineral tallow, which is a white substance of the consistence of tallow, and as greasy, although more brittle. It was found in the sea on the coasts of Finland, in the year 1736 ; and is also met with in some rocky parts of Persia. It is near one-fifth lighter than tallow ; burns with a blue flame, and a smell of grease, leaving a black viscid matter behind, which is more difficultly con- sumed. 3. Elastic bitumen, .or mineral caout- chouc, of which there are two varieties. Be- side these, there are other bituminous sub- stances, as jet and amber, which approach the harder bitumens in their nature ; and all the varieties of pit-coal, and the bituminous schis- tus, or shale, which contain more or less of bitumen in their composition. See the differ- ent kinds of bitumen and bituminous sub- stances, in then- respective places in the order of the alphabet. BITUMINOUS LIMESTONE is of a lamellar structure, susceptible of polishing, emits an unpleasant smell when rubbed, and has a brown or black colour. Heat converts it into quicklime. It contains 8.8 alumina; 0.6 silica; 0.6 bitumen; and 89.75 carbonate of lime. It is found near Bristol, and in Galway, in Ireland. The Dalmatian is so charged with bitumen, that it may be cut like soap, and is used for building houses. When the walls are reared, fire is applied to them, and they burn white. BLACK CHALK. This mineral has a bluish-black colour ; a slaty texture ; soils the BLE 209 BLE lingers, and is meagre to the touch. It con- tains about G4 silica, 11 alumina, 11 carbon, with a little iron and water. It is found in primitive mountains, and also sometimes near coal formations. It occurs in Caernarvonshire, and in the island of Isla. BLACK JACK. The miners distinguish blende, or mock lead, by this name. It is an ore of zinc. BLACK LEAD. See PLUMBAGO. BLACK WADD. One of the ores of manganese. BLEACHING. The chemical art by which the various articles used for clothing are deprived of their natural dark colour and rendered white. The colouring principle of silk is undoubt- edly resinous. Hence M. Baume proposed the following process, as the best mode of bleaching it. On six pounds of yellow raw silk, disposed in an earthen pot, 48 pounds of alcohol, sp. gr. 0.867, mixed with I2oz. mu- riatic acid, sp. gr. 1.100, are to be poured. After a day's digestion, the liquid passes from a fine green colour to a dusky brown. The silk is then to be drained, and washed with alcohol. A second infusion with the above acidulated alcohol is then made, for four or six days, after which the silk is drained and washed with alcohol. The spirit may be recovered by saturating the mingled acid with alkali or Mine, and distilling. M. Baume says, that silk may thus be made to rival or surpass in whiteness and lustre the finest specimens from Nankin. But the or- dinary method of bleaching silk is the follow- ing: The silk, being still raw, is put into a bag of thin linen, and thrown into a vessel of boiling river water, in which has been dis- solved good Genoa or Toulon soap. After the silk has boiled two or three hours in that water, the bag being frequently turned, it is taken out to be beaten, and is then washed in cold water. When it has been thus tho- roughly washed and beaten, they wring it slightly, and put it for the second time into the boiling vessel, filled with cold water, mixed with soap and a little indigo; which gives it that bluish cast commonly observed in white silk. When the silk is taken out of this second water, they wring it hard with a wooden peg, to press out all the water and soap; after which they shake it, to untwist it, and sepa- rate the threads. Then they suspend it in a kind of stove constructed for that purpose, where they burn sulphur; the vapour of which gives the last degree of whiteness to the silk. The method of bleaching woollen stuffs. There are three ways of doing this. The first is with water and soap ; the second with the vapour of sulphur ; and the third with chalk, indigo, and the vapour of sulphur. Jikaching with toap and water.- After the stuffs are taken out of the fuller's mill, they are put into soap and water, a little warm, in which they are again worked by the strength of the arms over a wooden bench : this finishes giving them the whitening which the fuller's mill had only begun. When they have been suffi- ciently worked with the hands, they are washed in clear water and put to dry. This method of bleaching woollen stuffs is called the Natural Method. Bleaching with sulphur They begin with washing and cleansing the stuffs thoroughly in river water ; then they put them to dry upon poles or perches. When they are half dry, they stretch them out in a very close stove, in which they burn sulphur ; the vapour of which diffusing itself, adheres by degrees to the whole stuff, and gives it a fine whitening: this is commonly called Bleaching by the Flower, or Bleaching of Paris, because they use this me- thod in that city more than any where else. The colouring matter of linen and cotton is also probably resinous; at least the experi- ments of Mr.Kirwan on alkaline lixivia satu- rated with the dark colouring matter, lead -to that conclusion. By neutralizing the alkali with dilute muriatic acid, a precipitate re- sembling lac was obtained, soluble in alcohol, in solutions of alkalis, and alkaline sul- phurets. The first step towards freeing vegetable yarn or cloth from their native colour is fermenta- tion. The raw goods are put into a large wooden tub, with a quantity of used alkaline lixivium, in an acescent state, heated to about the hundredth degree of Fahr. It would be better to use some uncoloured fermentable matter, such as soured bran or potatoe paste, along with clean warm water. In a short time an intestine motion arises, air bubbles escape, and the goods swell, raising up the loaded board which is used to press them into the liquor. At the end of from 18 to 48 hours, according to the quality of the stuffs, the fer- mentation ceases, when the goods are to be immediately withdrawn and washed. Much advantage may be derived by the skilful bleacher, from conducting the acetous ferment- ation completely to a close, without incurring the risk of injuring the fibre by the putrefactive fermentation. The goods are next exposed to the action of hot alkaline lixivia, by bucking or boiling, or both. The former operation consists in pour- ing boiling hot ley on the cloth placed in a tub ; after a short time drawing off the cooled liquid below, and replacing it above by hot lixivium. The most convenient arrangement of apparatus is the following: Into the mouth of an egg- shaped iron boiler, the bottom of a large tub is fixed air-tight. The tub is furnished with a false bottom pierced with holes, a few inches above the real bottom. In the latter, a valve is placed, opening downwards, but which may be readily closed by the upward pressure of p BLE 210 BLE steam. From the side of the iron boiler, a little above its bottom, a pipe issues, which, turning at right angles upwards, rises parallel to the outside of the bucking tub, to a foot or two above its summit The vertical part of this pipe forms the cylinder of a sucking pump, and has a piston and rod adapted to it. At a few inches above the level of the mouth of the tub, the vertical pipe sends offa lateral branch, which terminates in a bent down nozzle, over a hole in the centre of the lid of the tub. Under the nozzle, and immediately within the lid, is a metallic circular disc. The boiler being charged with lixivium, and the tub with the washed goods, a moderate fire is kindled. At the same time, the pump is set a-going either by the hand of a workman, or by ma- chinery. Thus the lixivium, in its progres- sively heating state, is made to circulate con- tinually down through the stuffs. But when it finally attains the boiling temperature, the piston rod and piston are removed, and the pressure of the included steam alone forces the liquid up the vertical pipe, and along the hori- zontal one in an uninterrupted stream. The valve at the bottom of the tub, yielding to the accumulated weight of the liquid, opens from time to time, and replaces the lixivium in the boiler. This ingenious self-acting apparatus was in- vented by Mr. John Laurie of Glasgow, and a representation of it accompanies Mr. Ramsay's excellent article, Bleaching, in the Edinburgh Encyclopaedia. By its means, labour is spared, the negligence of servants is guarded against, and fully one-fourth of alkali saved. It is of great consequence to heat the liquid very slowly at first. Hasty boiling is incom- patible with good bleaching. When the ley seems to be impregnated with colouring mat- ter, the fire is lowered, and the liquid drawn off by a stop-cock; at the same time that water, at first hot and then cold, is run in at top, to separate all the dark-coloured lixivium. The goods are then taken out and well washed, either by the hand with the wash stocks, or by the rotary wooden wheel with hollow com- partments, called the dash wheel. The strength of the alkaline lixivium is varied by different bleachers. A solution of potash, ren- dered caustic by lime, of the specific gravity 1.014, or containing a little more than 1 per cent, of pure potash, is used by many bleachers. The Irish bleachers use barilla lixivium chiefly, and of inferior ajkaline power. The routine of operations may &e conveniently presented in a tabular form. \^ A parcel of gootts consists of 360 pieces of those linens which are called Britannias. Each piece is 35 yards long, weighing on an average 10 pounds. Hence the weight of the whole is 3600 pounds avoirdupois. These linens are first washed, and then subjected to the acetous fermentation, as above described. They then undergo the following operations : 1. Bucked with 60 Ibs. pearl ashes, washed and exposed on the field. 2. Ditto with 80 Ibs. ditto ditto. 3. Ditto 90 potashes ditto. 4. Ditto 80 ditto ditto. 5. Ditto 80 ditto ditto. 6. Ditto 50 ditto ditto. 7. Ditto 70 ditto ditto. 8. Ditto 70 ditto ditto. 9. Soured one night in dilute sulphuric acid. 10. Bucked with 50 Ibs. pearl ashes, wash- ed and exposed. 11. Immersed in the oxymuriate of potash for 12 hours. 12. Boiled with 30 Ibs. pearl ashes, washed and exposed. 13. Ditto 30 ditto ditto. 14. Soured and washed. The linens are then taken to the rubbing board, and well rubbed with a strong lather of black soap, after which they are well washed in pure spring water. At this period they are carefully examined, and those which are fully bleached are laid aside to be blued and made up for the market. Those which are not fully- white, are returned to be boiled and steeped in the oxymuriate of potash, and soured until they are fully white. By the above process, 690 Ibs. of commercial alkali are used in bleach- ing 360 pieces of linen, each measuring 35 yards. Hence, the expenditure of alkali would be a little under 2 Ibs. a-piece, were it not that some part of the above linens may not be tho- roughly whitened. It will, therefore, be a fair average to allow 2 Ibs. for each piece of such goods. On the above process we may remark, that many enlightened bleachers have found it ad- vantageous to apply the souring at a more early period, as well as the oxymuriatie solution. According to Dr. Stephenson, in his elaborate paper on the linen and hempen manufactures, published by the Belfast Literary Society, 10 naggins, or quarter pints of oil of vitriol, are sufficient to make 200 gallons of souring. This gives the proportion, by measure, of 640 water to 1 of acid. Mr. Parkes, in describing the bleaching of calicoes in his Chemical Essays, says, that throughout Lancashire, one measure of sulphuric acid is used with 46 of water, or one pound of the acid to 25 pounds of water ; and he states, that a scientific calico printer in Scotland makes his sours to have the specific gravity 1.0254 at 110 of Fahrenheit ; which dilute acid contains at least l-25th of oil of vitriol. Five or six hours' immersion is employed. In a note Mr. Parkes adds, that in bleach- ing common goods, and such as are not de- signed for the best printing, the specific gravity of the sours is varied from 1.0146 to 1.0238, if taken at the atmospheric temperature. Most bleachers use the strongest alkaline lixiviums at first, and the weaker afterwards. As to BLE 211 BLE the strength of the oxymuriatic steeps, as the bleacher terms them, it is difficult to give cer- tain data, from the variableness of the chlorides of potash and lime. Mr. Parkes, in giving the process of the Scotch bleacher, says, that after the calicoes have been singed, steeped, and squeezed, they are boiled four successive times, for 10 or 12 hours each, in a solution of caustic potash of a specific gravity from 1.0127 to 1.0156, and washed thoroughly between each boiling. " They are then immersed in a solution of the oxymuriate of potash, originally of the strength of 1.0625, and afterwards reduced with 24 /times its measure of water. In this prepara- tion they are suffered to remain 12 hours." Dr. Stephenson says, that, for coarse linens, the steep is made by dissolving 1 Ib. of oxy- muriate of lime in 3 gallons of water, and afterwards diluting with 25 additional gallons. The ordinary specific gravity of the oxymuriate of lime steeps, by Mr. Ramsay, is 1.005. But from these data little can be learned ; because oxymuriate of lime is always more or less mixed with common muriate of lime, or chloride of calcium, a little of which has a great effect on the hydrometric indications. The period of immersion is 10 or 12 hours. Many bleachers employ gentle and long con- tinued boiling without bucking. The opera- tion of souring was long ago effected by butter- milk, but it is more safely and advantageously performed by the dilute sulphuric acid uni- formly combined with the water by much agi- tation. Mr. Tennent's ingenious mode of uniting chlorine with pulverulent lime, was one of the greatest improvements in practical bleaching. When this chloride is well prepared and pro- perly applied, it will not injure the most deli- cate muslin. Magnesia has been suggested as a substitute for lime ; but the high price of this alkaline earth must be a bar to its general em- ployment. The muriate of lime solution result- ing from the action of unbleached cloth on that of the oxymuriate, if too strong, or too long applied, would weaken the texture of cloth, as Sir H. Davy has shown. But the bleacher is on his guard against this accident ; and the pro- cess of souring, which follows most commonly the oxymuriatic steep, thoroughly removes the adhering particles of lime. Mr. Parkes informs us, that calicoes for madder work, or resist work, or for the fine pale blue dipping, cannot without injury be bleached with oxymuriate of lime. They re- quire, he says, oxymuriate of potash. 1 be- lieve this to be a mistake. Test liquors made by dissolving indigo in sulphuric acid, and then diluting the sulphate with water, or with infu- sion of cochineal, are employed to measure the blanching power of the oxymuriatic or chloridic solutions. But they are all more or less uncer- tain, from the changeableness of these colour- ing matters. I have met with indigo of appa- rently excellent quality, of which four parts were required to saturate the same weight of oxymuriate of lime, as was saturated by three parts of another indigo. Such coloured liquors, however, though they give no absolute mea- sure of chlorine, afford useful means of com- parison to the bleacher. Some writers have recommended lime and sulphuret of lime as detergent substances in- stead of alkali; but I believe no practical bleacher of respectability would trust to them alone. Lime should always be employed, how- ever, to make the alkalis caustic ; in which state their detergent powers are greatly in- creased. The coarser kinds of muslin are bleached by steeping, washing, and then boiling them in a weak solution of pot and pearl ashes. They are next washed, and afterwards boiled in soap alone, and then soured in very dilute sulphuric acid. After being washed from the sour, they are boiled with soap, washed, and immersed in the solution of chloride of lime or potash. The boiling in soap, and immersion in the oxymu- riate, is repeated, until the muslin is of a pure white colour. It is finally soured and washed in pure spring water. The same series of ope- rations is used in bleaching fine muslins, only soap is used in the boilings commonly to the exclusion of pearl ash. Fast coloured cottons are bleached in the following way : After the starch or dressing is well removed by cold water, they are gently boiled with soap, washed, and immersed in a moderately strong solution of oxymuriate of potash or lime. This process is repeated till tne white parts of the cloth are sufficiently pure. They are then soured in dilute sulphuric acid. If these ope- rations be well conducted, the colours, instead of being impaired, will be greatly improved, having acquired a delicacy of tint which no other process can impart. After immersing cloth or yarn in alkaline ley, if it be exposed to the action of steam heated to 222, in a strong vessel, it will be in a great measure bleached. This operation is admirably adapted to the cleansing of hospital linen. The following is the practice followed by a very skilful bleacher of muslins near Glas- gow. " In fermenting muslin goods, we surround them with our spent leys from the temperature of 100 to 150* F., according to the weather, and allow them to ferment for 36 hours. In boiling 112 Ibs. = 112 pieces of yard-wide muslin, we use 6 or 7 Ibs. of ashes and 2 Ibs. of soft soap, with 360 gallons of water, and allow them to boil for 6 hours ; then wash them and boil them again, with 5 Ibs. of ashes, and 2 Ibs. of soft soap, and allow them to boil 3 hours ; then wash them with water, and im- merse them into the solution of oxymuriate of lime, at 5 on the test tube, and allow them to remain from 6 to 1 2 hours ; next wash them, P2 BLE BLO and immerse them into diluted sulphuric acid at the specific gravity of 3 on Twaddle's hydrometer 1.0175, and allow them, to re- main an hour. They are now well washed, and boiled with 2 Ibs. of ashes, and 21bs. of soap, for half an hour ; afterwards washed and immersed into the oxymuriate of lime as before, at the strength of 3 on the test tube, which is stronger than the former, and allow- ed to remain for 6 hours. They are again washed and immersed into diluted sulphuric acid at the specific gravity of 3 on Twaddle's hydrometer =. 1.015. If the goods be strong, they will require another boil, steep, and sour. At any rate, the sulphuric acid is well washed out before they receive the finishing operation with starch. ' ' With regard to the lime, which some use instead of alkali, immediately after fermenting, the same weight of it is employed as of ashes. The goods are allowed to boil in it for 15 minutes, but not longer, otherwise the lime will injure the fabric." The alkali may be recovered from the brown lixivia, by evaporating them to dryness and gentle ignition of the residuum. But, in most situations the expense of fuel would exceed the value of the recovered alkali. A simpler mode is to boil the foul lixivium with quick- lime, and a little pipe-clay and bullock's blood. After skimming, and subsidence, a tolerably pure ley is obtained. Under the head of Chlorine, we have de- scribed the preparation of this article ; and the chief circumstance respecting it to be no- ticed here is the apparatus, which must be on an extensive scale, and adapted to the purpose of immersing and agitating the goods to be bleached. The process of distillation may be performed in a large leaden alembic, gg, Plate I. fig. 1 supported by an iron trevet f, in an iron boiler e. This is heated by a fur- nace Z>, of which a is the ashhole, c the place for introducing the fuel j d is the handle of a stopper of burnt clay, for regulating the draught To the top of the alembic is fitted a leaden cover i, which is luted on, and has three perforations; one for the curved glass or leaden funnel ft, through which the sul- phuric acid is to be poured in ; one in the centre for the agitator 7", made of iron coated witfi lead ; and the third for the leaden tube Z, three inches in diameter internally, through which the gas is conveyed into the tubulated leaden receiver m. To prevent the agitator from reaching to the bottom of the alembic, it is furnished with a conical leaden collar, adapted to a conical projection round the hole in the centre of the cover, to which it becomes so closely fitted by means of its rotary mo- tion, as to prevent the escape of the gas. The tube I passing through the aperture m. to the bottom of the intermediate receiver nearly, which is two-thirds full of water, deposits there the little sulphuric acid that may arise j while the chlorine gas passes through the tub sorbed by the 3 charcoal. No action on caustic strontita. =. parts, fuses into a clear glass, becomes milky on cooling: in strong heat, bub- bles, and absorbed by the charcoal. ) No sensible quantity 5 dissolved. f Fuse readily with ef- fervescence into a ^ clear glass, which becomes opaque I byFl. I Like Baryta. Clear glass : opaque byFl. Fuses with effer- vescence ; with more carbonate clear glass; crystallizes on cool- ing. As with borax, but foam and in- tumesce; end in a clear glass. Ditto. Fuses in large quan- tity ; clear glass. Fuses with effer- vescence. Carbonutc . ... Carbonate BLO 220 BLO ASSAY. E SODA. r EATED WITH FLUX BORAX. is> SALT OF PHOSPHORUS. No action. Like lime. Fuses readily ; clear glass ; saturated wit magnesia, opaque on cooling. Alumina . . . . . . . Swells up; forms a infusible compoum No action. Fuses slowly ; perma nently clear glass. Clctir ijrlciss with Permanently clear glass. Glucina large proportion o ^\s witii oor&x* the assay ; opaqu Yttria Lite Glucipa byFl. L/lKC (jrlUClflci4 . Like Glucina. Similar to Glucins Like Olucins LrfiJcc O Jiicinfl^ but uis- solves more difficultly. Silica Fuses with brisk effer Fuses veryslowly; per Very small portion dis- Vlolybdic Acid vescence ; clear glass P. W. effervesces; clea manently clear glass P. W. clear glass ii solves ; clear flass. P. W. and in O. F. glass ; becomes O.F. greenish glass while milky on cooling. hot ; colourless, cole C. fuses, absorbed ant C. and in R. F. glass in R. F. becomes reduced. becomes dirty brown, opaque ; dull blue but not opaque. while hot ; clear an< fine greenon cooling. 3. same phenomena. P W. dark yellow P. W. and O. F. clear ) F vellowisli xide of Tellurium. . . . J .W. colourless glass; '. W. clear colour- 'he same. white on cooling. less glass ; white on 2. reduced. cooling. C. becomes grey and opaque. Oxide of Columbium. . ombines with effer- Colourless, clear glass, ?uses easily ; glass vescence, but not becomes opaque by permanently clear. fused or reduced. Fl. Oxide of Titanium i'uses into a clear dark J . W. fuses easily; 3.F. clear colourless yellow glass ; white glass, colourless; be- glass. or grey-white on comes milk-white l.F. and on C. glass. cooling, and crys- by Fl. yellowish hot ; on tallizes with evolu- tion of great heat. 1. F. glass assumes a dark amethyst co- cooling, first red, then very fine bluish . not reducible. lour,but transparent. violet. BLO 221 BLO ASSAY. H SODA. EATED WITH FLUXE BORAX. S> SALT OP PHOSPHORUS. [n large quantity, on C. and R. F. glass, dull yellow ; when cold, deep blue. Oxides of Uranium .... C. brown yellow ; not P. W. dark yellow P.W. and O.F. clear fused. glass ; in R. F. be- yellow glass ; cold, comes dirty green. straw-yellow, slight- ly green. C. and R.F. fine green Oxides of Cerium .... C. not fused, soda ab- O.F. fine red, or deep glass. O. F. fine red glass ; sorbed ; white or orange yellow glass ; colourless when cold, grey-white protox- ide remains on the colour flies on cool- ing ; cold, yellowish and quite limpid. surface. tint. Enamel white by Fl. In R. F. loses its colour. Oxide of Manganese.. ?.F. fuses, green glass, clear ; cold, bluish O. F. clear, amethyst colour, glass ; colour The same, but colour not so deep. In fu- green. flies in R. F. sion in O. F. boils, C. not reduced. and gives ofFgas ; in R.F. fuses quietly. C. not fused, but re- duced with flame ; O.F. fuses easily, clear glass becomes milky Nearly the same- white fumes, which byFl. _ j f , .,.,.. cover the charcoal Oxide of Cadmium .... P.W. not fused. P.W. yellowish glass, Dissolves in large C. reduced, sublimes, colour flies on cool- quantity, clear glass; and leaves a circular ing ; on C. .glass on cooling, milk yellowish mark. bubbles, Cadmium white. reduced, sublimes and leaves yellow oxide. C. absorbed and re- O.F. duU red glass, be- Similar to borax. duced ; not fused. comes clear and yel- lowish or colourless by cooling. C. and R. F. bottle- green glass, or bluish green. Oxide of Cobalt P. W. pale red, by Fuses readily, deep The same, the colour transmitted light ; blue glass. appears violet by Oxide of Nickel grey, cold. C. absorbed and re- 0. F. orange yellow ; candle light. As with borax, but the duced ; not fused. or reddish glass ; be- colour flies almost comes yellow, or nearly colourless, on wholly on cooling. cooling. Bismuth Oxide of Bismuth . . . O. F. colourless glass. R. F. partly reduced, O. F. yellowish -brown glass, hot; colour- muddy greyish glass. less, but not quite clear, cold. R. F. clear and co- lourless glass, hot ; . T. , ;'" opaque and greyish ' >_ black, cold. Oxides of Tin.., P.W. effervesces, tu- Fuses with great diffi- As with borax. mified, infusible culty ; permanently mass. C. readily reduced. clear glass. BLO BLO ASSAY. Hi SODA. ATED WITH FLUXE5 BOHAX. 5. SALT OF PHOSPHORUS. Oxide of Lead P.W. clear glass ; be- comes yellowish and opaque on cooling. C. instantly reduced. P.W. fine green glass, hot ; on cooling, co- lourless and opaque. C. absorbed and re- duced. ?.\V. clear glass ; yel- Clear colourless glass. O. F. similar to borax. R. F. glass, usually red, opaque, and like an enamel. O. F. yellowish glass viewed by transmit- ted light by day, by candlelight reddish. R. F. greyish. Oxide of Copper low, hot; on cooling, colourless. D. flows over the sur- face and reduces. O.F. fine green glass, which in R.F. be- comes colourless, hot ; but cinnabar- red, and opaque when solid. O.F. glass becomes milky, or opaline, on cooling. R.F. greyish. Mercury Oxide of Silver Gold Platina Iridium Rhodium Palladium ASSAY. WITH OTHER REAGENTS. REMARKS. Alkalis, Baryta Hydrate. . Carbonate. Strontita. . . . Hydrate . Carbonate . Lime Carbonate. Magnesia. . . Alumina Glucina Yttria Zirconia Silica .., Molybdic Acid N. C. a globule of different shades of red; colour flies on cooling. N. C. exhibit a black, or greyish- black colour ; do not fuse. N. C. black or dark grey mass, infusible. N. C. flesh colour when quite cold. N. C. fine blue glass, heat when cold. N. C. black or dark grey mass. The alkalis are not readily dis- tinguishable by the blowpipe. Lithla leaves a dull yellow stain, when heated to redness on platina foil. Ammonia may be known by heating the assay with soda; it gives off a pun- gent vapour, which turns the yellow colour of moistened tur- meric paper brown. with strong The blue colour is only distinctly seen by daylight. N. C. blue glass when perfectly fused. The part not perfectly fused with nitrate of cobalt has a reddish- blue disagreeable colour. In the inclined glass tube, fuses, gives off vapour, which con- denses partly on the tube as a white powder, partly on the assay in brilliant pale yellow crystals. BLO BLO \mgstic Acid , ASSAY. )xide of Chrome ntimony Oxide of Antimony} Antimonious Acid. > Antimonic Acid . . j Oxide of Tellurium . . . Oxide of Columbium Oxide of Titanium . . Oxides of Uranium Oxides of Cerium Oxide of Manganese . Oxide of Zinc Oxide of Cadmium Oxide of Iron .... Oxide of Cobalt . . . , gxide of Nickel ^Bismuth Oxide of Bismuth Oxides of Tin Dxide of Lead Oxide of Copper Mercury Oxide of Silver Gold Platina Iridium Rhodium Palladium . . WITH OTHF.H REAGENTS. C. black or greyish black. Vith subcarbonate of potassa black glass when cold. REMARKS. tungstic acid contain iron, the glass with salt of phosphorus is blood-red in R. F. Tin makes it green or blue. ntimony does not sublime at the fusing point of glass. On charcoal when red, ignition continues spontaneously. In tube open at both ends, it gives off white fumes. The oxide and acids of anti- mony behave alike with th fluxes. [etallic tellurium heated in : glass matrass, first gives off vapour, and then a grey metal lie sublimate of tellurium. In a tube open at both ends, emit! abundant fumes which con dense in a white fusible pow der. or the rest of the phenomena see the original work. very minute portion of manga nese gives a green glass wit soda. The reduction of iron from th peroxide to protoxide is facil tated by tin. 'n a glass matrass does not sub lime at the fusing point o glass. In an open tube scarce' gives off any fumes ; the meta becomes covered with a du brown fused oxide, of a sligl yellowish tint, when cold. A.11 the compounds of mercu are volatile ; mixed with tin iron filings, and heated in glass tube, metallic mercur distils over. C These metals have no action o the fluxes, which can OR serve to detect the foreig ^ metals theymay be combine I with. They are best ex mined by cupellation wi lead. BLO BLO Under the mineral species and calculus, their habitudes with the blowpipe are given. Dr. Robert Hare, Professor of Natural Phi- losophy in the University of Philadelphia, published, in the first volume of Brace's Mineralogical Journal, an account of very in- tense degrees of heat, which he had produced and directed on different bodies, by a jet of flame, consisting of hydrogen and oxygen gases, in the proportion requisite for forming water. The gases were discharged from sepa- rate gasometers, and were brought in contact only at a common orifice or nozzle of small diameter, in which their two tubes terminated. In the first number of the Journal of Science and Arts, is a description of a blowpipe con- trived by Mr. Brooke, and executed by Mr. Newmann, consisting of a strong iron box, with a blowpipe nozzle and stop-cock, for re- gulating the emission of air, which had been previously condensed into the box, by means of a syringe screwed into its top. John George Children, Esq. first proposed to Sir H. Davy the application of Newmann's apparatus to the mixture of oxygen and hy- drogen, immediately after Sir H. had disco- vered that the explosion from oxygen and hy- drogen would not communicate through very small apertures ; and he first tried the experi- ment himself with a fine glass capillary tube. The flame was not visible at the end of this tube, being overpowered by the brilliant star of the glass ignited at the aperture. Dr. Clarke, after being informed by Sir H. Davy that there would be no danger of explo- sion in burning the compressed gases, by suf- fering them to pass through a fine thermometer tube l-80th of an inch diameter, and three inches in length ; commenced a series of ex- periments, which were attended with most important and striking results. By the sug- gestion of Professor Gumming, there has been enclosed in the iron box a small cylinder of safety, about half filled with oil, and stuffed at top with fine wire gauze. The condensed gases must pass from the large chamber into this small one, up through the oil, and then across the gauze, before they can reach the stop-cock and blowpipe nozzle. By this means, the dangerous explosions, which had occurred so frequently as would have deterred a less intrepid experimenter than Dr. Clarke, are now obviated. It is still, however, a prudent precaution, to place a wooden screen between the box and the operator. The box is about five inches long, four broad, and three deep. The syringe is joined to the top of the box by a stop-cock. Near the upper end of the sy- ringe, a screw nozzle is fixed in it at right angles, to which the stop- cock of a bladder containing the mixed gases may be attached. When we wish to inject the gases, it is proper to draw the piston to the top, before opening the lower stop-cock, lest the flame of the jet should be sucked backward, and cause explo- sion. It is likewise necessary to see that no little explosion has dislodged "the oil from the safety cylinder. A bubbling noise is heard when the oil is present. A slight excess of hydrogen is found to be advantageous. Platinum is not only fused the instant it is brought in contact with the flame of the ignited gases, but the melted metal runs down in drops. Dr. Clarke has finally fused the astonishing quantity of half an ounce at once, by this jet of flame. In small quantities, it burns like iron wire. Palladium melted like lead. Pure lime becomes a wax-yellow vitri- fication. A lambent purple flame always ac- companies its fusion. The fusion of magnesia is also attended with combustion. Strontites fused with a flame of an intense amethystine colour, and after some minutes there appeared a small oblong mass of shining metal in its centre. Silex instantly melted into a deep orange-coloured glass, which was partly vola- tilized. Alumina melted with great rapidity into globules of a yellowish transparent glass. In these experiments, supports of charcoal, platinum, or plumbago, were used with the same effect. The alkalis were fused and vola- tilized the instant they came in contact with the flame, with an evident appearance of com- bustion. The following refractory native compounds were fused. Rock crystal, white quartz, noble opal, flint, calcedony, Egyptian jasper, zircon, spinelle, sapphire, topaz, cymophane, pycnite, andalusite, wavellite, rubellite, hyper- stene, cyanite, talc, serpentine, hyalite, lazulite, gadolinite, leucite, apatite, Peruvian emerald, Siberian beryl, potstone, hydrate of magnesia, subsulphate of alumina, pagodite of China, Iceland spar, common chalk, Arragonite, diamond. Gold exposed on pipe-clay to the flame was surrounded with a halo of a lively rose colour, and soon volatilized. Stout iron wire was rapidly burned. Plumbago was fused into a magnetic bead. Red oxide of titanium fused, with partial combustion. Red ferriferous cop- per blende, oxides of platinum, grey oxide of manganese, crystallized oxide of manganese, wolfram, sulphuret of molybdenum, siliceo- calcareous titanium, black oxide of cobalt, pechblende, siliciferous oxide of cerium, chro- mate of iron, and ore of iridium, were all, ex- cept the second last, reduced to the metallic state, with peculiar, and for the most part, splendid phenomena. Jade, mica, amianthus, asbestus, melt like wax before this potent flame. But the two most surprising of Dr. Clarke's experiments were the fusion of the meteoric stone from L'Aigle, and its conversion into iron ; and the reduction of barium, from the earth barytes and its salts. Some nitrate of barytes, put into a cavity, at the end of a stick of charcoal, was exposed to the ignited gas. It fused with vehement ebullition, and BLO 225 BOL metallic globules were clearly discernible in the midst of the boiling fluid, suddenly form- ing, and as suddenly disappearing. On check- ing the flame, the cavity of the charcoal was studded over with innumerable globules of a metal of the most brilliant lustre and white- ness, resembling the purest platinum after fusion. Some globules were detached and dropped into naphtha, where they retained for some time their metallic aspect. Their specific gravity was 4.00. Dr. Clarke fused together a bead of barium and one of platinum, each weighing one grain. The bronze-coloured alloy weighed two grains, proving a real combination. The alloy of barium and iron is black and brittle. Barium is infusible before the blowpipe per sc ; but with borax it dissolves like barytes, with a chrysolite-green colour, and disclosing metallic lustre to the file. The alloy of barium and copper is of a vermilion colour. When silex is mixed into a paste with lamp-oil, and ex- posed on a cavity of charcoal to the flame, it runs readily into beads of various colours. If these be heated in contact with iron, an alloy of silicum and iron is obtained, which dis- closes a metallic surface to the file. Magne- sium and iron may be alloyed in the same way. By using from two to three volumes of hydrogen to one of oxygen, and directing the flame on pure barytes, supported on pincers of slate, Dr. Clarke apparently revived barium in larger quantities, so as to exhibit its quali- ties for some time. It gradually, however, passes again into pure barytes. Muriate of rs&^um, placed in a charcoal crucible, yielded tM|f*:ietal rhodium, brilliant like platinum. It isf'inalleable on the anvil. Oxide of ura- nium, from Cornwall, was also reduced to the metallic state. It is now generally believed, that Dr. Clarke had been mistaken, with regard to the reduction of barytes to the metallic vState ; and that the globules which he formed, owed their lustre and polish to the fusion which the earth had undergone. We shall conclude this article by the fol- lowing experiment of Dr. Clarke's : If you take two pieces of tin-foil and platinum-foil of equal dimensions, and roll them together, and place the roll upon charcoal, and direct the flame of a candle cautiously towards the edges of the roll, at about a red heat, the two metals will combine with a sort of explosive force, scattering their melted particles off the char- coal, and emitting light and heat in a very surprising manner. Then there will remain upon the charcoal a film of glass, which, by further urging the flame towards it, will melt into a highly transparent globule of a sapphire- blue colour. Also if the platinum and tin be placed beside each other, as soon as the pla- tinum becomes heated, you will observe a beautiful play of blue light upon the surface of the tin, becoming highly iridescent before it melts. BLUE (PRUSSIAN). A combination of oxide of iron with cyanogen. See ACID (PRUSSIC), and IRON. BLUE (SAXON). The best Saxon blue colour may be given by the following compo- sition : Mix one ounce of the best powdered indigo with four ounces of sulphuric acid, in a glass bottle or matrass, and digest it for one hour with the heat of boiling water, shaking the mixture at different times : then add twelve ounces of water to it, and stir the whale well, and when grown cold filter it. Mr. Poerner adds one ounce of good dry potash at the end of twenty-four hours, and lets this stand as much longer, before he dilutes it with water. The cloth should be prepared with alum and tartar. BOG ORES. Sse ORES OF IRO* . BOLE. A massive mineral, having a per- fectly conchoidal fracture, a glimmering in- ternal lustre, and a shining streak. Its colours are yellow-red, and brownish black, when it is called mountain soap. It is translucent or opaque. Soft, so as to be easily cut, and to yield to the nail. It adheres to the tongue, has a greasy feel, and falls to pieces in water. Sp. grav. 1.4 to 2. It may be polished. If it be immersed in water after it is dried, it falls asunder with a crackling noise. It occurs in wacke and basalt, in Silesia, Hessia, and Sienna in Italy, and also in the cliffs of the Giant's Causeway, Ireland. The black va- riety is found in the trap rocks of the Isle of Sky. BOLOGNIAN STONE. Lemery re- ports, that an Italian shoemaker, named Vin- cenzo Casciarolo, first discovered the phosphoric property of the Bolognian stone. It is the ponderous spar, or native sulphate of barytes. If it be first heated to ignition, then finely powdered, and made into a paste with muci- lage ; and this paste, divided into pieces a quarter of an inch thick, and dried in a mo- derate heat, be exposed to the heat of a wind furnace, by placing them loose in the midst of the charcoal ; a pyrophorus will be obtained, which, after a few minutes' exposure to the sun's rays, will give light enough in the dark to render the figures on the dial-plate of a watch visible. BOLETICACID. See ACID (BOLKTIC). BOLETUS. A genus of mushroom, of which several species have been subjected to chemical examination by MM. Braconnot and Bouillon La Grange. 1. Boletus juglandis, in 1260 parts, yielded 1118.3 water, 95.68 fungin, 18 animal matter insoluble in alcohol, 12 osmazome, 7.2 vege- table albumen, 6 fungate of potash, 1.2 adi- pocere, 1.12 oily matter, 0.5 sugar of mush- rooms, and a trace of phosphate of potash. 2. Boletus laricis, used on the continent in Q BON 226 BON medicine under the name of ttfffiric. It is in white, light, friable pieces, of which the outside is like dark-coloured leather. Its taste, at first sweetish, soon passes into bitterness and acrimony. Its infusion in water is yellowish, sweet tasted, and reddens vegetable blues. It contains muriate of potash, sulphate of lime, and sulphate of potash. Water boiled on agaric, becomes gelatinous on cooling ; and if the water be dissipated by evaporation, ammonia is ex- haled by the addition of lime. Resin of a yellow colour, with a bitter- sour taste, may be extracted from it by alcohol. It yields ben- zoic acid, by Scheele's process. The strong acids act with energy on agaric, and the nitric evolves oxalic acid. Fixed alkalis convert it into a red jelly, which emits an ammoniacal smell. 3. Boletus igniarius is found in most coun- tries, and particularly in the Highlands of Scotland, on the trunks of old ash and other trees. The French and Germans prepare it abundantly for making tinder, by boiling in water, drying, beating it, and steeping it in a solution of nitre, and again drying it. In France it is called amadou* in this country German tinder. It has been recommended in surgery, for stopping haemorrhage from wounds. It imparts to water a deep brown colour, and an astringent taste. The liquid consists of lime, muriate of potash, and a brown extractive matter. When the latter is evapo- rated to dryness, and burned, it leaves a good deal of potash. Phosphates of lime and mag- nesia, with some iron, are found in the inso- luble matter. Alkalis convert it with, some difficulty into a soapy liquid, exhaling am- monia. No benzoic acid, and little animal matter, are found in this boletus. 4. Boletus pseudo-igniariuS) yielded to Braconnot, water, fungin, a sweetish muci- lage, boletate of potash, a yellow fatty matter, vegetable albumen, a little phosphate of pot- ash, acetate of potash, and fungic acid com- bined with a base. 5. Boletus viscidus was found by Braconnot to be composed, in a great measure, of an animal mucus, which becomes cohesive by heat. BONE. The bones of men and quad- rupeds owe their great firmness and solidity to a considerable portion of the phosphate of lime which they contain. When these are rasped small, and boiled in water, they afford gelatinous matter, and a portion of fat or oil, which occupied their interstices. Calcined human bones, according to Ber- zelius, are composed, in 100 parts, of 81.9 phosphate of lime, 3 fluate of lime, 10 lime, 1.1 phosphate of magnesia, 2 soda, and 2 car- bonic acid. 100 parts of bones by calcination are reduced to 63. Fourcroy and Vauquelin found the following to be the composition of 100 parts of ox bones : 51 solid gelatin, 37-7 phosphate of lime, 10 carbonate of lime, and 1.3 phosphate of magnesia; but Berzel.ius gives the following as their constituents : 33.3 cartilage, 55.35 phosphate of lime, 3 fluate of lime, 3.85 carbonate of lime, 2.05 phos- phate cf magnesia, and 2.45 soda, with a little common salt. About l-30th of phosphate of magnesia was obtained from the calcined bones of fowls, by Fourcroy and Vauquelin. When the enamel of teeth, rasped down, is dissolved in muriatic acid, it leaves no albumen, like the other bones. Fourcroy and Vauquelin state its components to be 27-1 gelatin and water, 72-9 phosphate of lime. Messrs. Hatchett and Pepys rate its composition at 78 phos- phate of lime, 6 carbonate of lime, and 16 water and loss. Berzelius, on the other hand, found only 2 per cent, of combustible matter in teeth. The teeth of adults, by Mr. Pepys, consist of 64 phosphate of lime, 6 carbonate of time, 20 cartilage, and 10 water or loss. The fossil bones from Gibraltar, are composed of phosphate of lime and carbonate, like burnt bones. Much difference of opinion exists with regard to the existence of fluoric acid in the teeth of animals, some of the most eminent chemists taking opposite sides of the question. It appears that bones buried for many cen- turies still retain their albumen, with very little diminution of its quantity. Fourcroy and Vauquelin discovered phos- phate of magnesia in all the bones they exa- mined, except human bones. The bones of the horse and sheep afford about l-36th of phosphate of magnesia ; those of fish nearly the same quantity as those of the ox. They account for this by observing, that phosphate of magnesia is found in the urine of man, but not in that of animals, though both equally take in a portion of magnesia with their food. The experiments of Mr. Hatchett show, that the membranous or cartilaginous sub- stance, which retains the earthy salts within its interstices, and appears to determine the shape of the bone, is albumen. Mr. Hatchett observes, that the enamel of teeth is analogous to the porcellanous shells, while mother-of- pearl approaches in its nature to true bone. A curious phenomenon with respect to bones, is the circumstance of their acquiring a red tinge, when madder is given to animals with their food. The bones of young pigeons will thus be tinged of a rose colour in twenty-four hours, and of a deep scarlet in three days ; but the bones of adult animals will be a fort- night in acquiring a rose colour. The bones most remote from the heart are the longest in acquiring this tinge. Mr. Gibson informs us, that extract of logwood too, in considerable quantity, will tinge the bones of young pigeons purple. On desisting from the use of this food, however, the colouring matter is again taken up into the circulation, and carried off, the bones regaining their natural hue in a short time. It was said by Du Hamel, that the bones would become coloured and colour. BOR 227 BOR less in concentric layers, if an animal were fed alternately one week with madder, and one week without; and hence he inferred, that the bones were formed in the same manner as the woody parts of trees. But he was mis- taken in the fact; and indeed had it been true, with the inference he naturally draws from it, the bones of animals must have been out of all proportion larger than they are at present. Bones are of extensive use in the arts. In their natural state, or dyed of various colours, they are made into handles of knives and forks, and numerous articles of turnery. We have already noticed the manufacture of volatile alkali from bones, the coal of which forms bone-black ; or, if they be afterwards calcined to whiteness in the open air, they constitute the bone ashes of which cupels are made, and which, finely levigated, are used for cleaning articles of paste, and some other trinkets, by the name of burnt hartshorn. The shavings of hartshorn, which is a species of bone, afford an elegant jelly ; and the shavings of other bones, of which those of the calf are the best, are often employed in their stead. On this principle, Mr. Proust has recom- mended an economical use of bones, particu- larly with a view to improve the subsistence of the soldier. He first chops them into small pieces, throws them into a kettle of boiling water, and lets them boil about a quarter of an hour. When this has stood till it is cold, a quantity of fat, excellent for culinary pur- poses when fresh, and at any time fit for making candles, may be taken off the liquor. This in some instances amounted to an eighth, and in others even to a fourth, of the weight of the bones. After this the bones may be ground, and boiled in eight or ten times their weight of water, of which that already used may form a part, tijl about half is wasted, when a very nutritious jelly will be obtained. The boiler should not be of copper, as this metal is easily dissolved by the jelly ; and the cover should fit very tight, so that the heat may be greater than that of boiling water, but not equal to that of Papin's digester, which would give it an empyreuma. The bones of meat that have been boiled are nearly as pro- ductive as fresh bones ; but Dr. Young found those of meat that had been roasted afforded no jelly, at least by simmering, or gentle boiling. BORACIC ACID. See ACID (Bo- RACIC). This acid has been found native on the edges of hot springs, near Sapo in the ter- ritory of Florence ; also attached to specimens from the Lipari Islands, and from Monte Rotondo, to the west of Sienna. It is in small pearly scales, and also massive, fusing at the flame of a candle into a glassy globule. It consists, by Klaproth's analysis, of 86 boracic acid, 11 ferruginous sulphate of manganese, and 3 sulphate of lime. BORACITE. Borate of magnesia. It is found in cubic crystals, whose fracture is un- even, or imperfectly conchoidal. Shining greasy lustre; translucent: so hard as to strike fire with steel ; of a yellowish, greyish, or greenish-white. Sp. grav. 2-56. It be- comes electric by heat; and the diagonally opposite solid angles are in opposite electrical states. It fuses into a yellow enamel, after emitting a greenish light. Vauquelin's analysis gives, 83-4 boracic acid, and 16.6 magnesia. It occurs in gyp- sum in the Kalkberg in the duchy of Bruns- wick, and at Segeberg, near Kiel in Holstein. BORATE. Salts composed with Boracic Acid. BORAX. The origin of borax was for a long time unknown in Europe. Mr. Grill Abrahamson, however, sent some to Sweden in the year 1772, in a crystalline form, as dug out of the earth in Thibet, where it is called Pounnxa, Mypoun, and Houipoun ; it is said to have been also found in Saxony, in some coal pits. It does not appear that borax was known to the ancients, their chrysocolla being a very different substance, composed of the rust of copper, triturated with urine. The word borax is found for the first time in the works of Geber. Borax is not only found in the East, but likewise in South America. Mr. Anthony Carera, a physician established at Potosi, in- forms us, that this salt is abundantly obtained at the mines of Requintipa, and those in the neighbourhood of Escapa, where it is used by the natives in the fusion of copper ores. The purification of borax by the Venetians and the Hollanders, was for a long time kept secret. Chaptal finds, after trying all the processes in the large way, that the simplest method consists in boiling the borax strongly, and for a long time, with water. This solu- tion being filtered, affords by evaporation crystals, which are somewhat foul, but may be purified by repeating the operation. Purified borax is white, transparent, rather greasy in its fracture, affecting the form of six-sided prisms, terminating in three-sided or six-sided pyramids. Its taste is styptic; it converts syrup of violets to a green; and when exposed to heat, it swells up, boils, loses its water of crystallization, and becomes converted into a porous, white, opaque mass, commonly called Calcined Borax. A stronger heat brings it into a state of quiet fusion ; but the glassy substance thus afforded, which is transparent, and of a greenish-yellow colour, is soluble in water, and effloresces in the air. It requires about eighteen times its weight of water to dissolve it at the temperature of sixty degrees of Fahrenheit ; but water at the boil- ing heat dissolves three times this quantity. Its component parts, according to Kirwan, are, boracic acid 34, soda 17? water 47. For Q2 BOH 228 BOK an account of the neutral borate of soda, and other compounds of this acid, see ACID (Bo- HACIC). Borax is used as an excellent flux in doci- mastic operations. It enters into the compo- sition of reducing fluxes, and is of the greatest use in analysis by the blowpipe. It may be applied with advantage in glass manufactories ; for when the fusion turns out bad, a small quantity of borax re-establishes it. It is more especially used in soldering; it assists the fusion of the solder, causes it to flow, and keeps the surface of the metals in a soft or clean state, which facilitates the operation. *It is scarcely of any use in medicine. Its acid, called sedative salt, is used by some physicians; and its name sufficiently indicates its supposed effects. Mixed with shell lac, in the pro- portion of one part to five, it renders the lac soluble by digestion in water, heated near boiling. BORON. The combustible basis of bo- racic acid. The easiest and most economical method of preparing boron, is to decompose an alkaline borofluate by potassium. For this purpose, borofluate of potash is formed by mixing fluate of potash with a solution of borate of potash. The borofluate falls in a gelatinous precipitate, which by desiccation assumes the form of a fine mealy white coloured powder. Its taste is weakly bitter, but not at all acid, nor does it redden litmus paper. It is an- hydrous. 100 parts of water dissolve only 1.42 of this salt; but boiling water dissolves it in considerably larger quantity. It is slightly soluble also in boiling alcohol. When ignited it fuses, and gives off fluoboric acid gas ; but for complete decomposition it requires a much longer continued, and more violent heat than the corresponding salt of silica (fluo-silicate of potash). The borofluate is soluble in boiling hot solutions of the alkalis and their carbon- ates, and as the liquid cools it crystallizes again unaltered. As boracic acid, even by protracted fusion, cannot be completely de- prived of water, and as it absorbs an additional quantity during pulverization, a rather violent detonation is thereby caused during the re- duction of boracic acid by potassium ; so that a portion of the mixture is in general pro- jected from the crucible. On the contrary, when the borofluate of potash has been suf- ficiently dried, the sound at the instant of re- duction is scarcely audible, and for every atom of potassium expended we obtain the corre- sponding quantity of boron. The boron must be well washed with a solution of sal am- moniac, and finally with alcohol, because when pure water is employed for this purpose, a considerable quantity passes in the dissolved state through the filter. Snlphnret of lor on. Boron is capable of forming a sulphuret, but, contrary to what has been hitherto supposed, no combination takes place between the two substances, except in a temperature greatly exceeding the boiling point of sulphur. It takes fire and burns when strongly ignited in the vapour of sul- phur. The sulphuret is a white opaque mass. When put into water it is rapidly converted into sulphuretted hydrogen gas and boracic acid ; the liquid becomes at the same time more or less milky, in consequence of the pre- cipitation of sulphur. Berzelius is led to think, that boron is capable of combining in several distinct proportions with sulphur. Chloride of boron. Sir II. Davy ascertained, that boron even without the application of heat takes fire spontaneously in chlorine gas, and undergoes brilliant combustion. If it be how- ever very pure, and previously ignited in vacua, no combination takes place with chlorine till heat be applied. The product of the com- bustion is a new gas, which, in contact with the atmospheric air, smokes as strongly as fluoboric acid gas. It must be collected over mercury, which absorbs the excess of chlorine. This gas is colourless, and in consequence of the formation of muriatic acid at the expense of the atmospheric humidity, it has a strong suffocating odour. It is rapidly, but not in- stantaneously, absorbed by water, and when the proportion of the water is small, a quantity of boracic acid is deposited upon its surface. Alcohol also dissolves it, and acquires the same odour of ether as when it has absorbed muriatic acid gas. Chloride of boron, when mixed with ammoniacal gas, condenses and forms a salt, which may be sublimed unal- tered, but which is less volatile than sal am- moniac. If the salt be moistened previously to sublimation, there remains a quantity of boracic acid. 1 volume of the gas condenses l volume of ammoniacal gas. Chloride of boron is composed of Chlorine 90.743 Boron 9.257 Fluoric acid, unless aided by nitric acid, nei- ther oxidates nor dissolves boron. When boron is ignited with an alkaline carbonate, it detonates at the expense of the carbonic acid ; and when it is ignited with the hydrate of a fixed alkali, hydrogen gas is dis- engaged with effervescence, and boracic acid is formed. In the properties now brought under review, boron possesses so close a resemblance to sili- ciurn, that the two substances may be asso- ciated with one another, in the same manner as arsenic has been associated with phospho- rus, and selenium with sulphur. The affinities of boron are, however, stronger, and, in the lower temperatures, more active than those of silicium. Thus it detonates with nitre in a low red heat, with such energy that the ex- plosion may be compared almost to that of gunpowder. Berzelins, Annals of Phil. N. S. x. 129. M. Dumas states, that a mixture of borax BOV BRA earthy. Its colour is pearl and yellowish- , with sometimes reddish -while concentric and charcoal being put into contact with dry chlorine at a red heat, yields abundance of the chloride of boron. He took advantage of it in the analysis of boracic acid ; for when it decomposes water ic gives muriatic and boracic acids. But its most important property is that of forming a solid hydrate, susceptible of being reduced by hydrogen and the heat of a spirit lamp ; it becomes muriatic acid and boron, and in this way the latter substance may be obtained in large quantities. Ann. de Chim. xxxi. 433. BOTANY-BAY RESIN exudes spon- taneously from the trunk of the acarois rcsi- liifera of New Holland, and also from the wounded bark. It soon solidifies by the sun, into pieces of a yellow colour of various sizes. It pulverizes easily without caking ; nor does it adhere to the teeth when chewed. It has a slightly sweet astringent taste- It melts at a moderate heat. When kindled, it emits a white fragrant smoke. It is insoluble in water, but imparts to it the flavour of storax. Out of nine parts, six are soluble in water, and astrin- gent to the taste ; and two parts are woody fibre. BOTTLE GLASS. See GLASS. BOTRYOLITE is a mineral which occurs in mamillary concretions, formed of concentric layers; and also in botroidal masses, white and grey stripes. It has a rough and dull surface, and a pearly lustre internally. Fracture delicate, stellular, fibrous. Translucent on the edges. Brittle, but moderately hard. Sp. gr. 2.85. It is composed of 3o silica, 39.5 boracic acid, 13.5 lime, 1 oxide of iron, 0.5 water. It froths and fuses before the blowpipe into a white glass. It is found in a bed of gneiss near Arendahl, in Norway. It is regarded by some as a variety of datholite. BOULDER STONES. Rolled blocks of granite ; often found in valleys at a great dis- tance from the granite mountains, even where lakes and mountains of another structure in- tervene. See the Introduction to Cowjbearc and Phillip* s Geology of England and Wales,, pp. 29 and 30. See also D^Auluisson, Traiti de Geognosie, i. 231. and Annalcs de Chim. ei de Phys. torn. vii. and x. BOURNONITE. An antimonial sul- phuret of lead. BOVEY COAL. This is of a brown or brownish-black colour, and lamellar texture ; the laminae are frequently flexible when first dug, though generally they harden when ex- posed to the air. It consists of wood pene- trated with petroleum or bitumen, and fre- quently contains pyrites, alum, and vitriol: its ashes afford a small quantity of fixed al- kali, according to the German chemists ; but according to Mr. Mills, they contain none. By distillation it yields an ill-smelling liquor, jnixed with volatile alkali and oil, part of which is soluble in alcohol, and part insoluble, being of a mineral nature. It is found in England, France, Italy, Swit- zerland, Germany, Iceland, &c. BOYLE'S FUMING LIQUOR. Hydro, guretted sulphuret of ammonia. BRAIN OF ANIMALS. The brain has long been known to anatomists ; but it is only of late years that chemists have paid it any attention. It is a soft white substance, of a pulpy saponaceous feel, and little or no smell. Exposed to a gentle heat, it loses moisture, shrinks to about a fourth of its original bulk, and becomes a tenacious mass of a greenish- brown colour. When completely dried, it be- comes solid, and friable like old cheese. Ex-- posed to a strong heat, it gives out ammonia, swells up, melts into a black pitchy mass, takes fire, burns with much flame and a thick pungent smoke, and leaves a coal difficult of incineration. In its natural state, or moderately dried, it readily forms an emulsion by trituration with water, and is not separated by filtration. This solution lathers like soap-suds, but does not turn vegetable blue colours green. Heat throws down the dissolved brain in a flocculent form, and leaves an alkaline phosphate in solution. Acids separate a white coagulum from it ; and form salts with bases of lime, soda, and am- monia. Alcohol too coagulates it. Caustic fixed alkalis act very powerfully on brain even cold, evolving much ammonia and caloric. With heat they unite with it into a saponaceous substance. The action of alcohol on brain is most re- markable. When Fourcroy treated it four times in succession with twice its weight of well rectified alcohol, boiling it a quarter of an hour each time, in a long-necked matrass with a grooved stopple, the three first portions of alcohol, decanted boiling, deposited by cool- ing brilliant laminae of a yellowish-white co- lour, diminishing in quantity each time. The fourth deposited very little. The cerebral matter had lost 5-8ths of its weight; and by the spontaneous deposition, and the subsequent evaporation of the alcohol, half of this was re- covered in ncedly crystals, large scales, or gra- nulated matter. The other half was lost by volatilization. This crystallized substance, of a fatty appearance, was agglutinated into a paste under the finger; but did not melt at the heat of boiling water, being merely soft- ened. At a higher temperature it suddenly acquired a blackish-yellow colour, and exhaled during fusion an empyreumatic and ammo- niacal smell. This shows that it is not ana- logous to spermaceti, or to adipocere; but it seems more to resemble the fat lamellated crystals contained in some biliary calculi, which, however, do not soften at a heat of 234 F. or become ammoniacal and empyreu- matic at this temperature, as the crystalline cerebral oil does. 1 BRA 230 BRE A portion of this concrete oil, separated from the alcohol by evaporation in the sun, formed a granulated pellicle on its surface, of a consistence resembling that of soft soap. It was of a yellower colour than the former, and had a marked smell of animal extract, and a perceptible saline taste. It was diffusible in water, gave it a milky appearance, reddened litmus paper, and did not become really oily or fusible after the manner of an oil, till it had given out ammonia, and deposited carbon, by the action of fire or caustic alkalis. A similar action cf alcohol on the brain, nerves, and spinal marrow, is observed after long maceration in it cold, when they are kept as anatomical preparations. Vauquelin analyzed the brain, and found the following constituents in 100 parts: 80 water, 4.53 white fatty matter, 0.7 reddish fatty matter, 7 albumen, 1.12 osmazome, 1.5 phosphorus, 5.15 acids, salts, and sulphur. The medulla oblongata and nerves have the same chemical composition. The spontaneous change that brain under, goes in certain situations, has already been noticed under the article ADIPOCERE. BRANDY. This well known fluid h the spirit distilled from wine. The greatest quan- tities are made in Languedoc, where this ma- nufacture, upon the whole so pernicious to so- ciety, first commenced. It is obtained by dis- tillation in the usual method by a still, which contains five or six quintals of wine, and has a capital and worm tube applied. Its peculiar flavour depends, no doubt, on the nature of the volatile principles, or essential oil, which come over along with it, and likewise, in some measure, upon the management of the fire, the wood of the cask in which it is kept, &c. It is said, that our rectifiers imitate the flavour of brandy, by adding a small proportion of nitrous ether to the spirit of malt or molasses. See ALCOHOL. BRASS. A yellow-coloured compound metal, consisting of copper combined with about one-half of its weight of zinc. The best brass is made by cementation of calamine, or the ore of zinc, with granulated copper. See COPPER. BRASSICA RUBRA. The red cabbage affords a very excellent test both for acids and alkalis ; in which it is superior to litmus, being naturally blue, turning green with alkalis, and red with acids. The minced leaves may be dried before the fire till they become quite crisp, when they ought to be put into a bottle, and corked up. Hot water, poured on a little of the dried leaves, affords an extemporaneous test liquor for acids and alkalis. The purple petals of violets may be preserved in the same way; as well as those of the pink coloured lychnis, and scarlet rose. BRAZIL WOOD. The tree that affords this wood, the cacsalpina crista, is of the growth of the Brazils in South America, and also of the Isle of France, Japan, and elsewhere. It is chiefly used in the process of dyeing. The wood is considerably hard, is capable of a good polish, and is so heavy that it sinks in water. Its colour is pale when newly cut, but it be- comes deeper by exposure to the air. The various specimens differ in the intensity of their colour; but the heaviest is reckoned the most valuable. It has a sweetish taste when chewed, and is distinguished from red sanders, or sandal, by its property of giving out its colour 'with water, which this last does not. If the brazil wood be boiled in water for a sufficient time, it communicates a fine red colour to that fluid. The residue is very dark coloured, and gives out a considerable portion of colouring matter to a solution of alkali. Alcohol extracts the colour from brazil wood, as does likewise the volatile alkali ; and both these are deeper than the aqueous solution. The spirituous tincture, according to Dufay, stains warm marble of a purplish-red, which on increasing the heat becomes violet ; and if the stained marble be covered with wax, and considerably heated, it changes through all the shades of brown, and at last becomes fixed of a chocolate colour. The colours imparted to cloth by brazil wood are of little permanence. A very mi- nute portion of alkali, or even soap, darkens it into purple. Hence paper stained with it may be used as a test of saturation with the salts. Alum added to 'the decoction of this wood occasions a fine crimson-red precipitate, or lake, which is increased in quantity by the addition of alkali to the liquor. The crimson- red colour is also precipitated by muriate of tin : but it is darkened by the salts of iron. Acids change it to yellow, from which, how- ever, solution of tin restores it to its natural hue. The extract of brazil wood reddens litmus paper, by depriving it of the alkali which darkens it. BREAD. When flour is kneaded together with water, it forms a tough paste, containing these principles very little altered, and not easily digested by the stomach. The action of heat produces a considerable change in the gluten, and probably in the starch, rendering the compound more easy to masticate, as well as to digest. Hence the first approaches to- wards the making of bread consisted in parch- ing the corn, either for immediate use as food, or previous to its trituration into meal ; or else in baking the flour into unleavened bread or boiling it into masses more or less consist- ent; of all which we have sufficient indica- tions in the histories of the earlier nations, as well as in the various practices of the moderns. It appears likewise from the Scriptures, that the practice of making leavened bread is of very considerable antiquity ; but the addi- BRE BRE lion of yeast, or the vinous ferment, now so generally used, seems to be of modern date. Unleavened bread, in the form of small cakes, or biscuit, is made for the use of ship- ping in large quantities; but most of the bread used on shore is made to undergo, pre- vious to baking, a kind of fermentation, which appears to be of the same nature as the fer- mentation of saccharine substances : but is checked and modified by so many circum- stances, as to render it not a little difficult to speak with certainty and precision respecting it. When dough or paste is left to undergo a spontaneous decomposition in an open vessel, the various parts of the mass are differently affected, according to the humidity, the thick- ness or thinness of the part, the vicinity or remoteness of fire, and other circumstances less easily investigated. The saccharine part is disposed to become converted into alcohol, the mucilage has a tendency to become sour and mouldy, while the gluten in all proba- bility verges toward the putrid state. An entire change in the chemical attractions of the several component parts must then take place in a progressive manner, not altogether the same in the internal and more humid parts as in the external parts, which not only be- come dry by simple evaporation, but are acted upon by the surrounding air. The outside may therefore become mouldy or putrid, while the inner part may be only advanced to an acid state. Occasional admixture of the mass would of course not only produce some change in the rapidity of this alteration, but likewise render it more uniform throughout the whole. The effect of this commencing fermentation is found to be, that the mass is rendered more digest- ible and light ; by which last expression it is understood that it is rendered much more porous by the disengagement of elastic fluid, that separates its parts from each other, and greatly increases its bulk. The operation of baking puts a stop to this process, by evapo- rating great part of the moisture which is re- quisite to favour the chemical attraction, and probably also by still farther changing the nature of the component parts. It is then bread. Bread made according to the preceding me- thod will not possess the uniformity which is requisite, because some parts may be mouldy, while others are not yet sufficiently changed from the state of dough. The same means are used in this case as have been found effec- tual in promoting the uniform fermentation of large masses. This consists in the use of a leaven or ferment, which is a small portion of some matter of the same kind, but in a more advanced stage of the fermentation. After the leaven has been well incorporated by kneading into fresh dough, it not only brings on the fer- mentation with greater speed, but causes it to take place in the whole of the mass at the same time ; and as scon as the dough has by this means acquired a due increase of bulk from the carbonic acid, which endeavours to escape, it is judged to be sufficiently fermented, and ready for the oven. The fermentation by means of leaven or sour dough is thought to be of the acetous kind, because it is generally so managed, that the bread has a sour flavour and taste. But it has not been ascertained that this acidity proceeds frcm true vinegar. Bread raised by leaven is usually made of a mixture of wheat and rye, not very accurately cleared of the bran. It is distinguished by the name of rye bread ; and the mixture of these two kinds of grain is called bread-corn, or meslin, in many parts of (he kingdom, where it is raised on one and the same piece of ground, and passes through all the processes of reaping, thresh- ing, grinding, &c. in this mixed state. Yeast or barm is used as the ferment for the finer kinds of bread. This is the mucila- ginous froth which rises to the surface of beer in its first stage of fermentation. When it is mixed with dough, it produces a much more speedy and effectual fermentation than that obtained by leaven, and the* bread is accord- ingly much lighter, aud scarcely ever sour. The fermentation by yeast seems to be almost certainly of the vinous or spirituous kind. Bread is much more uniformly miscible with water than dough ; and on this circum- stance its good qualities most probably do in a great measure depend. A very great number of processes are used by cooks, confectioners, and others, to make cakes, puddings, and other kinds of bread, in which different qualities are required. Some cakes are rendered brittle, or as it is called short, by an admixture of sugar or of starch. Another kind cf brittleness is given by the ad- dition of butter or fat. White of egg, gum- water, isinglass, and other adhesive substances, are used, when it is intended that the effect of fermentation shall expand the dough into an ex- ceedingly porous mass. Dr. Percival has re- commended the addition of salep, or the nu- tritious powder of the orchis root. He says, that an ounce of salep, dissolved in a quart of water, and mixed with two pounds of flour, two ounces of yeast, and eighty grains of salt, produced a remarkably good loaf, weighing three pounds two ounces ; while a loaf made of an equal quantity of the other ingredients, without the salep, weighed but two pounds twelve ounces. If the salep be in too large quantity, however, its peculiar taste will be distinguishable in the bread. The farina of potatoes likewise, mixed with wheaten flour, makes very good bread. The reflect ing che- mist will receive considerable information on this subject from an attentive inspection of the receipts to be met with in treatises of cooking and confectionery. BRE 232 BRE Mr. Accum, in his late Treatise on Culi- nary Poisons, states, that the inferior kind of flour which the London bakers generally use for making loaves, requires the addition of alum to give them the white appearance of bread made from fine flour. "The bakers' flour is very often made of the worst kinds of damaged foreign wheat, and other cereal grains mixed with them in grinding the wheat into flour. In this capital, no fewer than six distinct kinds of wheaten flour are brought into the market. They are called fine flour, seconds, middlings, fine middlings, coarse middlings, and twenty- penny flour. Common garden beans and pease are also frequently ground up among the Lon- don bread flour. " The smallest quantity of alum that can be employed with effect to produce a white, light, and porous bread from an inferior kind of flour, I have my own baker's authority to state, is from three to four ounces to a sack of flour weighing 240 pounds." - " The following account of making a sack or five bushels of flour into bread, is taken from Dr. P. Maikham's Considerations on the In- gredients used in the Adulteration of Flour and Bread, p. 21. Five bushels flour, Eight ounces of alum, Fourlbs. salt, Half a gallon of yeast mixed, with about Three gallons of water. " Another substance employed by frau- dulent bakers is subcarbonate of ammonia. With this salt they realize the important con- sideration of producing light and porous bread from spoiled, or what is technically called sour flour. This salt, which becomes wholly con- verted into a gaseous substance during the ope- ration of baking, causes the dough to swell up into air bubbles, which carry before them the stiff dough, and thus it renders the dough po- rous ; the salt itself is at the same time totally volatilized during the operation of baking." " Potatoes are likewise largely, and perhaps constantly used by fraudulent bakers, as a cheap ingredient, to enhance their profit." " There are instances of convictions on record, of bakers having used gypsum, chalk, and pipe-clay, in the manufacture of bread. " Mr. E. Davy, Prof, of Chemistry at the Cork Institution, has made experiments, show- ing that from twenty to forty grains of common carbonate of magnesia, well mixed with a pound of the worst new seconds flour, mate- rially improved the quality of the bread baked with it. The habitual and daily introduction of a portion of alum into the human stomach, how- ever small, must be prejudicial to the exercise of its functions, and particularly in persons of a bilious and costive habit. And besides, as the best sweet flour never stands in need of alum, the presence of this salt indicates an inferior and highly acescent food ; which can- not fail to aggravate dyspepsia, and which may generate a calculous diathesis in the urinary or- gans. Every precaution of science and law ought therefore to be employed to detect and stop such deleterious adulterations, Brrad may be ana- lyzed for alum by crumbling it down when some- what stale in distilled water, squeezing the pasty mass through a piece of cloth, and then passing the liquid through a paper filter. A limpid infusion will thus be obtained. It is difficult to procure it clear if we use new bread or hot water. A dilute solution of muriate of barytes dropped into the filtered infusion, will indicate, by a white cloud, more or less heavy, the presence and quantity of alum. I find that genuine bread gives no precipitate by this treatment. The earthy adulterations are easily discovered by incinerating the bread at a red heat in a shallow earth vessel, and treating the residuary ashes with a little nitrate of ammo- nia. The earths themselves will then remain, characterized by their whiteness and insolu- bility. Under Process of Baking, in the Supple- ment to the Encyclopedia Britannica. we have the following statement : " An ounce of alum is then dissolved over the fire in a tin-pot, and the solution poured into a large tub, called by the bakers the seasoning-tub. Four pounds and a half of salt are likewise put into the tub and a pailful of hot water." Note on this pass- age. " In London, where the goodness of bread is estimated entirely by its whiteness, it is usual with those bakers who employ flour of an inferior quality, to add as much alum as common salt to the dough. Or, in other words the quantity of salt added is diminished one- half, and the deficiency supplied by an equal weight of alum. This improves the look of the bread very much, rendering it much whiter and firmer." In a passage which we shall presently quote, our author represents the bakers of London joined in a conspiracy to supply the citizens with bad bread. We may hence infer, that the full allowance he assigns of 2^ pounds of alum for every 2^ pounds of salt, will be adopted in converting a sack of flour into loaves. But as a sack of flour weighs 280 pounds, and furnishes on an average 80 quar- tern loaves, we have 2\ pounds divided by 80, 15750 grains or 197 grams, for the quan, tity present by this writer in a London quartern loaf. Yet in the very same page (39th of volume 2d) we have the following passage : " Alum is not added by all bakers. The writer of this article has been assured by seve- ral bakers of respectability, both in Edinburgh and Glasgow, on whose testimony he relies, and who made excellent bread, that they never employed any alum. The reason for adding BRE 233 BUI it given by the London bakers is, that it ren- ders the bread whiter, and enables them to separate readily the loaves from each other. This addition has been alleged by medical men, and is considered by the community at large, as injurious to the health, by occasion- ing constipation. But if we consider the small quantity of this salt added by the baker, not quite 5-j grains to a quartern loaf, we will not readily admit these allegations. Suppose an individual to eat the seventh part of a quar- tern loaf a-day, he would only swallow eight- tenths of a grain of alum, or in reality not quite so much as half a grain, for one-half of this salt consists of water. It seems absurd to suppose that half a grain of alum, swallowed at different times during the course of a day, should occasion constipation.-' Is it not more absurd to state 2$ pounds, or 86 ounces, as the alum adulteration of a sack of flour by the London bakers, and within a few periods to reduce the adulteration to one ounce ? That this voluntary abstraction of |f of the alum, and substitution of superior and more expensive flour, is not expected by him from the London bakers, is sufficiently evident from the following story. It would appear that one of his friends had invented a new yeast for fer- menting dough, by mixing a quart of beer barm with a paste made of ten pounds of flour and two gallons of boiling water, and keeping this mixture warm for six or eight hours. " Yeast made in this way," says he, " an- swers the purposes of the baker much better than brewers' yeast, because it is clearer, and free from the hop mixture, which sometimes injures the yeast of the brewer. Some years ago the bakers of London, sensible of the su- periority of this artificial yeast, invited a com- pany of manufacturers from Glasgow to esta- blish a manufactory of it in London, and pro- mised to use no other. About 5000/. accord- ingly were laid out on buildings and materials, and the manufactory was begun on a consider- able scale. The ale brewers, finding their yeast, for which they had drawn a good price, lie heavy on their hands, invited all the jour- neymen bakers to their cellars, gave them their full of ale, and promised to regale them in that manner every day, provided they would force their masters to take all their yeast from the ale brewers. The journeymen accordingly de- clared in a lody, that they would work no more for their masters unless they gave up taking any more yeast from the new manu- factory. The masters were obliged to comply ; the new manufactory was stopped ; and the inhabitants of London 'were obliged to continue to eat worse bread, because it was the interest of the ale brewers to sell the yeast. Such is the in fluence of journey vnen bakers in the me- tropolis of England !" This doleful diatribe seems rather extra- vagant ; for surely beer-yeast can derive no- thing noxious, to a porter-drinking psople> from a slight impregnation of hops ; while it must form probably a more energetic ferment than the fermented paste of the new company, which at any rate could be prepared in six or eight hours by any baker who found it to an- swer his purpose of making a pleasant eating bread. But it is a very serious thing for a lady or gentleman of sedentary habits, or in- firm constitution, to have their digestive pro- cess daily vitiated by damaged flour, whitened with 197 grains of alum per quartern loaf. Acidity of stomach, indigestion, flatulence, headachs, palpitation, costiveness, and urinary calculus, may be the probable consequences of the habitual introduction of so much acidulous and acescent matter. I have made many experiments on bread, and have found the proportion of almn very variable. Its quantity seems to be propor- tional to the badness of the flour ; and hence when the best flour is used, no alum need be introduced. That alum is not necessary for giving bread its utmost beauty, sponginess, and agreeableness of taste, is undoubted ; since the bread baked at a very extensive establish- ment in Glasgow, in which about 20 tons of flour were regularly converted into loaves in the course of a week, unites every quality of appearance, with an absolute freedom from that acido-astringent drug Six pounds of salt are used for every sack of 'flour ; which from its good quality generally affords 83 or 84 quartern loaves of the legal weight, of four pounds five ounces and a half each. The loaves lose nine ounces in the oven. For an account of the constituents of wheat fl-jur, see WHEAT. BRECCIA. An Italian term, frequently used by our mineralogical writers to denote such compound stones as are composed of agglutinated fragments of considerable size. When the agglutinated parts are rounded, the stone is called pudding-stone. Breccias are denominated according to the nature of their component parts. Thus we have calcareous breccias, or marbles ; and siliceous breccias, which are still more minutely classed, accord- ing to their varieties. BREWING. See BKER, ALCOHOL, and FERMENTATION. BRICK. Among the numerous branches of the general art of fashioning argillaceous earths into useful forms, and afterward harden- ing them by fire, the art of making bricks and tiles is by no means one of the least useful. Common clay is scarcely ever found in a state approaching to purity on the surface of the earth. It usually contains a large pro- portion of siliceous earth. Bergmann exa- mined several clays in the neighbourhood of Upsal, and made bricks which he baked with various degrees of heat, suffered them to cool, immersed them in water for a considerable time, and then exposed them to the open air for three years. They were formed of clay Bill 234 BRO and sand. The hardest were those into the composition of which a fourth part of sand had entered. Those which had been exposed for the shortest time to the fire were almost totally destroyed, and crumbled down by the action of the air. Such as had been more thoroughly burned, suffered less damage ; and in those which had been formed of clay alone, and were half vitrified by the heat, no change whatever was produced. On the whole he observes, that the propor- tion of sand to be used to any clay, in making bricks, must be greater the more such clay is found to contract in burning; but that the best clays are those which need no sand. Bricks should be well burned ; but no vitrification is necessary, when they can be rendered hard enough by the mere action of the heat. When a vitreous crust might be deemed necessary, he recommends the projection of a due quan- tity of salt into the furnace, which would pro- duce the effect in the same manner as is seen in the fabrication of the English pottery called stoneware. A kind of bricks called Jlre-lricJts are made from slate-clay, which are very hard, heavy, and contain a large proportion of sand. These are chiefly used in the construction of furnaces for steam-engines, or other large works, and in lining the ovens of glass-houses, as they will stand any degree of heat. Indeed they should always be employed where fires of any intensity are required. BRICKS (FLOATING). Bricks, that swim on water, were manufactured by the an- cients ; and Fabbroni discovered some years since a substance, at Castel del Piano, near Santa Fiora, between Tuscany and the States of the Church, from which similar bricks might be made. It constitutes a brown earthy bed, mixed with the remains of plants. Haviy calls it talc pulverulent silicifere, and Bro- chant considers it as a variety of meerschaum. The Germans name it bcrgmchl (mountain meal), and the Italians latte di luna, (moon milk). By Klaproth's analysis, it consists of 70 silica, 5 alumina, 3 oxide of iron, 12 water, and 1 loss, in 100 parts. It agrees nearly in composition with Kieselguhr. BRILLIANT. Diamond, cut in such a way as to reflect light most vividly, is called a brilliant. BRIMSTONE. See SULPHUR. BRIONIA ALBA. A root used in me- dicine. By the analysis of Vauquelin, it is found to consist in a great measure of starch, with a bitter principle, soluble hi water and alcohol, some gum, a vegeto-animal matter, precipitable by infusion of galls, some woody fibre, a little sugar, and supermalate and phos- phate of lime. It has cathartic powers ; but is now seldom prescribed by physicians. BRITISH GUM. When starch is ex- posed to a temperature between 600 and 700 it swells, and exhales a peculiar smell ; it be- comes of a brown colour, and in that state 13 employed by calico printers. It is soluble in cold water, and does not form a blue compound with iodine. Vauquelin found it to differ from gum in affording oxalic instead of mucous acid, when treated with nitric acid. Brandos Ma- nual, iii. 34. BROCATELLO. A calcareous stone or marble, composed of fragments of four colours, white, grey, yellow, and red. BROCHANTITE. A new mineral from the Bank mines of Ekaterinburg. Crystals in thin rectangular tables, of an emerald green colour, transparent; hardness as green car- bonate of copper on which they lie. Annals of Phil. viii. 241. BROME or BROMINE. A new ele- mentary body of the electro-negative class, so called from the Greek name jBfttyuug, faztor, because it possesses a very offensive smell. After passing for some time a current of chlorine through the mother water of salt works, a quantity of ether must be poured on the surface of the liquid, so as entirely to fill up the flask into which it has been put. These two liquids are to be thoroughly intermixed by strong agitation, and then left at rest for a few instants, to allow them to separate from each other. The ether is now seen floating in a stratum of a fine hyacinthine red ; while the mother water of the salt springs, deprived of colour, presents no more the lively and irri- tating odour of brome, but the soothing smell of the ether held in solution. The ethereous solution of brome loses even- tually its hue and disagreeable odour, on agi- tation with some alkaline substance, for ex- ample, with caustic potash. This absorbs the brome, and by agitating successively the mo- ther water of salt works, rendered yellow by ether, and the coloured ether with potash, it is possible to combine with a small quantity of this alkali, the whole brome, afforded from a very large body of water. The potash losing by degrees its alkaline qualities, is changed into a saline matter, so- luble in water, and which crystallizes in cubes by the evaporation of the liquid. From these cubic crystals brome is extracted. The pulverized crystals, mixed with pure peroxide of manganese, being put into a retort, sulphuric acid, diluted with half its weight of water, is poured in. Ruddy vapours imme- diately rise, which condense into drops of brome. These may be collected by plunging the neck of the retort to the bottom of a small receiver containing cold water. The brome which comes over in vapour is dissolved in this liquid ; but that which is condensed on the neck of the retort, under the form of little drops, falls to the bottom of the vessel from its great specific gravity. Whatever may be the affinity of water for this body, the layer of liquid which surrounds it, is soon saturated, and then enclosing the BRO 235 BRO brome on all sides, screens it from the solvent notion of the upper strata. Finally, to pro- cure it in a state of great purity, it is merely necessary to separate it, to free it from the water that it may retain, and to distil it from chloride of calcium. Brome appears under the form of a blackish- red liquid, when viewed in mass and by re- flected light, but of a hyacinthine red when a thin film of it is interposed between the light and the eye. Its very unpleasant smell reminds one of that of the oxides of chlorine, though it is far more intense. Its taste is peculiarly strong. It attacks organic substances, as wood, cork, &c., and particularly the skin, which it tinges yellow and corrodes. This hue disappears after some time ; but if the contact of the brome has continued somewhat long, the colour wears off only with the epidermis. It acts with energy on the animal functions. A drop let fall into the beak of a bird was sufficient to kill it. The specific gravity, taken on a minute quantity, was found to be 2.966- Brome does not congeal at a temperature of 0F. It is volatile. When a drop of it is put into a vessel, this is immediately filled with the peculiar deep ruddy vapours, very similar to the fumes of nitrous acid. It boils at 1 1 6.6 F. But it suffers no change of nature on being transmitted through an ignited tube. Brome is a non-conductor of voltaic elec- tricity ; for when a column of it, 3 or 4 lines long, is interposed in the circuit for decom- posing water, the electrical action ceases. Nor does electricity appear capable of de- composing brome ; for it neither suffers dimi- nution of volume, nor disengages any gas, when exposed to the action of that power. The vapours of brome cannot support com- bustion. A lighted taper plunged into them, is soon extinguished ; but before going out, it burns for some instants with a flame which is green at the base, and reddish towards the top, just as happens with chlorine gas. Brome is soluble in water, alcohol, and par- ticularly in ether. Sulphuric acid floats above brome, but dissolves a very minute portion of it. Oil of olives acts in a slow manner. It does not redden tincture of litmus, but it speedily deprives it of colour, nearly as chlo- rine would do. The sulphuric solution of in- digo is equally decoloured. Brome unites with hydrogen to form hydro- bromic acid. See ACID (HYDROBROMIC). The action of brome on the metals, presents the most striking points of resemblance be- tween it and chlorine. Antimony and tin burn when brought in contact with brome. Potas- sium, on uniting with it, disengages so much heat and light, that a detonation ensues suffi- ciently violent to break the vessel and project the materials. The bromides thus directly formed, for in- stance that of potassium, seem to be identical in their appearance and properties, with those obtained by treating the metallic oxides with hydrobromic acid, either in the dry way, or by evaporating their liquid combinations. The hydro-bromates are easily recognized by the faculty which they possess of becoming yellow, and evolving brome, when any body strongly attractive of hydrogen acts on them, such as chlorine, or the chloric and nitric acids ; whence the use of the first substance in the extraction of brome. All the bromides, indeed, are de- composed by chlorine with the disengagements of brome. Bromide of potassium crystallizes in cubes, or sometimes in long rectangular parallele- pipeds. It has a sharp taste. Exposed to the action of caloric it decrepitates, and undergoes igneous fusion, without undergoing any other change. Chlorine decomposes it at an elevated tem- perature, Brome is disengaged, and chloride of potassium remains. Iodine has no action on it, even at an elevated temperature. On the other hand, brome made to pass over fused iodide of potassium, disengages violet vapours in abundance. Boric acid does not decompose at a red heat, unless steam be transmitted over the ignited mixture. In this case, hydro-bromic acid is evolved. Solution of this salt in water does dissolve no more brome than simple water. Sulphuric acid decomposes it, with the dis- engagement of hydro-bromic acid and brome. Bromide ttf potassium, decomposed by sul- phuric acid, leaves sulphate of potash ; whence the composition of the bromide seems to be, in 100 parts, Brome . . 65.56 Potassium . . 34.44; whence the prime equivalent of brome comes out 9.5 to oxygen 1. This is nearly the half sum of the atomic weights of chlorine and iodine. Hydrobromate of ammonia^ is formed by the union of equal volumes of hydrobromic acid and ammonia. It may also be formed in the liquid way from hydrobromic acid, or by putting brome into water of ammonia. The results of this action are the emission of heat without light, the disengagement of azote, and the formation of hydrobromate of ammonia. Nothing corresponding to chloride of azote seems to be produced. Hydrobromate of ammonia is solid, white, becoming yellow in moist air, and thus ac- quires the faculty of reddening the blue of litmus paper. It crystallizes in long prism s, on which other smaller ones are implanted at right angles. It is volatilized by heat. BHO 236 BRO Hydrobr ornate of larytes. This salt is formed by agitating the ethereous solution of brome with hydrate of barytes, or by the direct union of barytes and hydrobromic acid. Hydrobromate of barytes fuses on exposure to heat. It is very soluble in water, as well as in alcohol. Its crystals grouped under an opaque mam- melated form, have no resemblance to the transparent scales of muriate of barytes. Hydrobromate of magnesia is an uncrystal- lizable, deliquescent salt, decomposed like the muriate by exposure to a high heat. Bromide of lead. When into a solution of a salt of lead some drops of a hydrobromate, dissolved in water, are poured, a white preci- pitate ensues of a crystalline aspect, like chlo- ride of lead. This precipitate on being strongly heated fuses into a red liquid, which exhales thin white vapours. It afterwards concretes on cooling into a fine yellow mass, like mineral yellow. The pulverulent bromide of lead is decomposable by the nitric and sulphuric acids, with disengagement of brome in the first case, and of brome with hydrobromic acid in the second. After it has acquired a stony hard- ness by fusion, it is no longer acted on by nitric acid, but yields only to boiling sulphuric acid. Dentobromide of tin. Tin dissolves in liquid hydrobromic acid with disengagement of hy- drogen. The resulting hydrobromate, evaporated to dryness, is transformed into a protobromide, very different from the combination obtained by the direct action of brome on tin, which is obviously a bi-bromide. Tin burns in contact with brome, and is converted into a solid compound, white, of a crystalline appearance, very fusible, and easily volatilized. This bromide diffuses in moist air slight traces of white vapours. It dissolves in water without producing heat, and is con- verted into the acid deuto-bromate. Placed in hot sulphuric acid it melts, and remains at the bottom of the liquid, in the form of drops of oil, without suffering any visible change. Nitric acid, on the other hand, produces in a few seconds a brisk evolution of brome. The deutebromide of tin, corresponding to the fuming liquor of Libavius, possesses few of the properties of this compound. Bromides of mercury. Mercury combines in several proportions with brome. A solution of an alkaline hydrobromate, acting on the protonitrate of mercury, determines the form- ation of a white precipitate, similar to calomel, and which appears to be a proto- bromide of this metal. Brome attacks mercury power- fully. The combination takes place with a disengagement of heat, without light. A white matter results, sublimablc by heat, so- luble in water, alcohol, and especially in ether, precipitable in a red or yellow form by alkalis, and presenting thus many analogies with cor- rosive sublimate. It is characterized, how- ever, by the faculty of affording mcldy va- pours of brome, when treated with nitric, and still more so with sulphuric acid, on account of the higher heat to which the latter may be subjected. Bromide of silver. The nitrate of silver produces with the soluble hydrobromates, a curdy precipitate of bromide of silver. This compound, of a pale canary-yellow hue when dried in the shade, blackens when moist in the light, but less easily than chlo- ride of silver. Like it, it is insoluble in water, soluble in water of ammonia, and insoluble in nitric acid, which products no effect on it, even at its boiling heat; but boiling sulphuric acid disengages from it some vapours of brome. Bromide of silver fuses by heat into a red- dish liquid, which concretes by cooling into a substance of a yellow colour, and a horny appearance. Hydrogen in the gaseous state can also effect its decomposition. Metallic silver and hydrobromic acid result. The bro- mide of silver was analyzed on this principle. A quantity exactly weighed was introduced into a mixture of pure zinc granulated, and dilute sulphuric acid. The silver was revived, and its weight was taken after the whole zinc had been completely dissolved away. The mean of two experiments, which differed little from each other, gave for the composition of this body, in 100 parts, Silver . . . 58.9 Brome fj-yv*- > 4* ; #** 41.1 This makes the prime equivalent very nearly 9.0 to silver 1 3.75, which approaches very nearly to 10, the half sum of chlorine and iodine. Bromide of gold. Brome, and its aqueous solution, dissolve lamina: of gold. A yellow bromide is thus procured, which gives a violet stain to animal substances, and is decomposed by heat into brome and metallic gold. Platinum dissolves in bromo-nitric acid, though it is not acted on by brome at ordi- nary temperatures, and thereby forms a com- bination of a yellow colour, decomposable by heat, and which precipitates with the salts of potash and ammonia in a yellow powder, slightly soluble. BromC) when transmitted in vapour over potash, soda, barytes, and lime, at a red heat, occasions a lively incandescence. Oxygen gas is evolved, and there is found in the interior of the glass tube bromides of potassium, sodium, &c. Oxide of zinc in the same circumstances does not act on brome. Ignited sulphate of potash resists the action of brome ; but the alkaline carbonates are completely decom- posable by this new body, with the disengage- ment of carbonic acid and oxygen. Brome seems, in the liquid way, capable of forming BRO 237 BRO bromides of oxides, as of potash, &c. analogous to the chlorides of the same bases. When brome is put either by itself, or in its ethereous solution, into concentrated alkaline or earthy solutions, there is formed not only cubic crys- tals of the hydrobromates, but crystalline needles of bromates. It would appear, there- fore, that brome exercises on the metals a less energetic action than chlorine, but one superior to iodine. The iodides are decomposed by brome, and the bromides in their turn by chlo- rine. Iodine, which decomposes readily pot- ash and soda at an elevated temperature, does not act on barytes, with which it merely unites, forming an iodide of the earth. Brome, on the contrary, effects the decomposition of this base, and even of lime, but cannot act efficaciously on magnesia, which yields, however, to chlo- rine. Brome combines with chlorine at ordinary temperatures. This compound may be pro- cured by passing a current of chlorine gas through brome, and condensing the vapours disengaged by means of a freezing mixture. Chloride of brome appears under the form of a reddish-yellow liquid, much less deep than brome itself; of a brisk, penetrating odour, strongly exciting tears. Its taste is excessively disagreeable. It is fluid, and very volatile. Its vapours, of a dark yellow, similar to the colour of oxides of chlorine, have no resem- blance to the ruddy hue of the vapours of brome. It determines the combustion of metals, with which it probably forms chlorides and bromides. It is soluble in water, producing a liquid possessing the peculiar colour and odour of the compound, and which rapidly blanches litmus paper without reddening it. The alkalis con- vert this chloride into hydrochl orates and hy- drobromates. Bromide of Iodine. Iodine seems suscepti- ble of forming with brome two different com- pounds. When these two bodies are made to act on each other in certain proportions, a solid compound results, which produces, by heat, reddish - brown vapours, that condense into small crystals of the same colour, in form re- sembling leaves of fern. A new addition of brome transforms these crystals into a liquid compound, of an appearance similar to hydri- odic acid strongly charged with iodine. Liquid bromide of iodine is miscible with water, to which it communicates the faculty of decolour- ing, without reddening, litmus paper. Alkalis poured into this solution give birth to hydro- bromates and (hydr)iodates, as analogy indi- cates. Bromide of Phosphorus. Phosphorus and brome put in contact in a flask filled with car- bonic acid act suddenly on each other, with the production of heat and light. The resulting compound is divided into two portions; one solid, which sublimes into crystals in the upper part of the vessel ; the other liquid remains below. This latter compound appears to con- tain less brome than the crystalline solid, for by adding more brome to the former it assumes this state. The protobromide of phosphorus remains liquid even at a temperature of 10 Fahr. It feebly reddens litmus paper, an effect probably due to the materials not having been perfectly- dry. It passes readily into vapour, diffusing in the air pungent vapours. Like the proto-chloride, it can dissolve an excess of phosphorus, and thus acquire the pro- perty of setting fire to combustible bodies put in contact with it. It reacts on water with great energy, producing much heat, with a disengagement of hydrobromic acid, which may be received in a gaseous state when only a few drops of water have been used, but which remains dissolved in this liquid when more of it has been added. This acid solution sub- jected to evaporation leaves a residuum, which burns slightly when dried, and is thus con- verted into phosphoric acid. The deuto-bromidc of phosphorus is solid, and of a yellow colour. At a slightly elevated temperature it resolves itself into a red liquid, affording, by heat, vapours of the same hue. When the fused deuto-bromide is cooled, or when its vapours are condensed, in the first case, rhomboidal crystals are formed, and in the second, needles implanted on one another. Metals decompose it, producing bromides, and probably phosphurets. It diffuses in the air dense, pungent vapours. It effects the decomposition of water on the evolution of heat, and the production of hydro- bromic and phosphoric acids. When chlorine is made to act on either of these bromides of phosphorus, ruddy vapours of brome are exhaled, and chloride of phosphorus remains. Iodine cannot decompose these com- binations. On the contrary, violet vapours, and some bromide, are obtained when brome acts on the iodide of phosphorus. Bromide of Sulphur is obtained by pouring brome on sublimed sulphur. A liquid com- pound results of an oily appearance, of a red- dish tint, deeper thaa that of chloride of sul- phur, capable of diffusing like it, on contact with air, white vapours of a similar smell. Bromide of sulphur affects but feebly litmus paper ; but with water it strongly reddens it. Water in the cold acts slowly on bromide of sulphur ; but at the boiling temperature it produces a feeble detonation. Hydrobromic and sulphuric acids are formed along with sul- phuretted hydrogen ; whereas, in the same cir- cumstances, chloride of sulphur would have produced, without any explosion, muriatic, sulphurous, and sulphuric acids. Bromide of sulphur is decomposed . by chlorine, with dis- engagement of brome, and production of chlo- ride of sulphur. Hydro-carburet of Brome. Although car- BRO 238 BRO bon and brome have not apparently any ten- dency to combine, yet, on pouring a drop of brome into a flask filled with olefiant gas, it is instantly converted into a substance of an oily aspect heavier than water, colourless, and which presents no longer the lively odour of brome, but an ethereous smell more agreeable than that of the hydrocarburet of chlorine (chloric ether). The hydro-carburet of brome is volatile, and is decomposed in traversing an ignited glass tube. In this experiment a deposit of charcoal falls, and hydrobromic acid escapes. It burns on contact of a lighted taper, pro. ducing very acid vapours and dense smoke, consisting of finely divided charcoal. Bromide of carbon dees not seem to form when the above hydro-carburet of brome is exposed to the sunbeams. By distilling the mother water of salt springs, yellowed by chlorine, a similar hydro-carburet of brome is obtained, mixed with brome, which may be separated by the action of water. It happens occasionally that the whole brome is thus converted into hydro-carburet. This transformation is probably occasioned by the action of brome on a small quantity of organic matter which the springs contain, and which gives to the residuum of their evaporation the faculty of becoming black when strongly heated. The great affinity which brome has for hy- drogen enables us to anticipate its mode of action on organic bodies. It decomposes the greater part of them, with the production of hydrobromic acid, and the occasional precipi- tation of carbon. Brome dissolves readily in acetic acid, on which it acts but slowly. It is very soluble in alcohol and ether. The coloured solutions which these two liquids form lose their tint at the end of a few days, when hydrobromic acid is found combined with the liquid. The jixed oils have little effect on brome ; but on pouring a few drops of this substance into a volatile oil, that of turpentine or anise- seed, for instance, heat is occasioned, white vapours of hydrobromic acid exhale, and the essential oil is converted into a resinous sub- stance, of a yellowish colour, and tarry con- sistence, similar to turpentine. Camphor dissolves in brome, forming a crys- talline compound. Brome is present in sea- water in very minute quantity. The mother water of salt springs (salines') even contains very little of it, though the concentration has been carried very far. It exists there probably in the state of hydro- bromate of magnesia. Marine vegetables and animals alse contain brome. The incinerated plants of the Mediterranean afford a yellow tint when the product of then: lixiviation is treated with chlorine. Notable quantities of brome may be extracted from the mother waters of kelp that afford iodine. The best method of obtaining the brome from this com- pound matter, is to precipitate the iodine by a salt of copper, to separate by filtration the in- soluble iodide of this metal, to evaporate the liquid, and to treat the residuum with sulphuric acid and manganese Balard, Annales de Chirn. et Phys. xxxii. 337. M. Serullas has furnished some additional facts on Brome, in a memoir read to the Academy of Sciences on the 15th January, 1827. Solidification of Brome. By plunging a tube containing some of it into a freezing mix- ture at 4 Fahr. the brome became instantly solid, and very hard, and it broke by a blow. He formed a hydro-carburet of brome, by pro- jecting on it, in excess, a small quantity of hydriodide of carbon. The decomposition is instantaneous, with heat and a hissing noise. One part of brome is substituted for the iodine, combining with the carburetted hydrogen, fur- nishing an additional example of the displace- ment of iodine by brome. The hydrocarburet of brome, after washing with potash water, is colourless, very volatile, denser than water, of a penetrating ethereous smell, and a taste ex- cessively saccharine, which it communicates to water poured over it, in which it is slightly soluble. Hydro- carburet of brome remains solid at a temperature of about 42 Fahr. It is then hard, and breaks like camphor. Hydrobromic ether may be obtained nearly in the same way as hydriodic ether is prepared by M. Serullas, viz. by acting on alcohol with phosphuret of iodine, to which a little iodine is successively added, by distilling off the alcohol and separating the ether which it holds in solu- tion, by cold water. Annales de Chim. et de Phys. xxv. 323. Hydrobromic ether is colourless and trans- parent after long repose, denser than water, of a strong ethereous odour, a pungent taste, and very volatile. It does not change its co- lour, like hydriodic ether, by being kept under water. Cyanide of brome was formed by putting two parts of cyanide of mercury into the sealed end of a glass tube, plunging this in iced water, and adding 1 part of brome. A lively action takes place with heat, and the cyanide crystal- lizes in long needles in the upper part of the tube. These may be distilled over into a cooled receiver-tube. It resembles very closely the cyanide of iodine, but is more volatile. It is also very poisonous, even in its vapour. BRONZE. A mixed metal, consisting chiefly of copper, with a small proportion of tin, and sometimes other metals. It is used for casting statues, cannon, bells, and other articles, in all which the proportions of the ingredients vary. BRONZITE. This massive mineral has a pseudo-metallic lustre, frequently resembling bronze. Its colour is intermediate between yellowish-brown and pinchbeck-brown. Lus- BRU BRU tre shining ; structure lamellar with joints, parallel to the lateral planes of a rhomboidal prism ; the fragments are streaked on the sur- face. It is opaque in mass, but transparent in thin plates. White streak ; somewhat hard, but easily broken. Sp. gr. 3.2. It is com- posed of 60 silica, 27.5 magnesia, 10.5 oxide of iron, and 0.5 water. It is found in large masses in beds of serpentine, near Kranbat, in Upper Stiria ; and in a syenitic rock in Glen Tilt, in Perthshire. BROOKITE. In examining some well defined crystals from Snowdon, which had been classed by some with rutile, by others with sphene, M. Levy found a substance which cer- tainly differs from both, its form being de- rivable from a right rhombic prism, while the primitive form of rutile is a square prism, and that of sphene an oblique rhombic prism. See figures of it in Annals of Phil. ix. 140. BROWN SPAR. Pearl Spar, or Sidero- calcite. It occurs massive, and in obtuse rhomboids with curvilinear faces. Its colours are white, red, and brown, or even pearl-grey and black. It is found crystallized in flat and acute double three sided pyramids, in oblique six-sided pyramids, in lenses and rhombs. It is harder than calcareous spar, but yields to the knife. Its external lustre is shining, and internal pearly. Sp. gr. 2.88. Translucent, crystals semitransparent ; it is easily broken into rhomboidal fragments. It effervesces slowly with acids. It is composed of 49.19 carbonate of lime, 44.39 carbonate of mag- nesia, 3.4 oxide of iron, and 1.5 manganese, by Hisinger's analysis. Klaproth found 32 carbonate of magnesia, 7-5 carbonate of iron, 2 carbonate of manganese, and 51.5 carbonate of lime. There is a variety of this mineral of a fibrous texture, flesh-red colour, and massive. BRUCIA, or BRUCINE. A new vege- table alkali, lately extracted from the bark of the false angustura, or Brucia antidyscnterica, by MM. Pelletier and Caventou. After being treated with sulphuric ether, to get rid of a fatty matter, it was subjected to the action of alcohol. The dry residuum, from the eva- porated alcoholic solution, was treated with Goulard's extract, or solution of subacetate of lead, to throw down the colouring matter, and the excess of lead was separated by a current of sulphuretted hydrogen. The nearly colour- less alkaline liquid was saturated with oxalic acid, and evaporated to dryness. The saline mass being freed from its remaining colouring particles by absolute alcohol, was then decom- posed by lime or magnesia, when the brucia was disengaged. It was dissolved in boiling alcohol, and obtained in crystals, by the slow evaporation of the liquid. These crystals, when obtained by very slow evaporation, are oblique prisms, the bases of which are paral- lelograms. When deposited from a saturated solution in boiling water, by cooling, it is in bulky plates, somewhat similar to boracic acid in appearance. It is soluble in 500 times its weight of boiling water, and in 850 of cold. Its solubility is much increased by the colour- ing matter of the bark- Its taste is exceedingly bitter, acrid, and durable in the mouth. When administered in doses of a few grains, it is poisonous, acting on animals like strychnia, but much less violently. It is not affected by the air. The dry crystals fuse at a temperature a little above that of boiling water, and assume the appearance of wax. At a strong heat it is resolved into car- bon, hydrogen, and oxygen ; without any trace of azote. It combines with the acids, and forms both neutral and super-salts. Sulphate of brucia crystallizes in long slender needles, which appear to be four-sided prisms, termi- M nated by pyramids of extreme fineness. It is very soluble in water, and moderately in alco- hol. Its taste is very bitter. It is decomposed by potash, soda, ammonia, barytes, strontites, lime, magnesia, morphia, and strychnia. The bisulphate crystallizes more readily than the neutral sulphate. The latter is said to be composed of Sulphuric acid, 8.84 5 Brucia, 91.16 51.582 Muriate of brucia forms in four-sided prisms, terminated at each end by an oblique face. It is permanent in the air, and very soluble in water. It is decomposed by sulphuric acid. Concentrated nitric acid destroys the alkaline bases of both these salts. The muriate con. sists of Acid, 5.953 4.625 Brucia, 94.046 72.5 Phosphate of brucia is a crystallizable, solu- ble, and slightly efflorescent salt. The nitrate forms a gummy-looking mass ; the binitrate crystallizes in acicular four-sided prisms. An excess of nitric acid decomposes the brucia into a matter of a fine red colour. Acetate and oxalate of brucia both crystallize. Brucia is insoluble in sulphuric ether, the fixed oils, and very slightly in the volatile oils. Wlren ad- ministered internally, it produces tetanus, and acts upon the nerves without affecting the brain, or the intellectual faculties. Its intensity is to that of strychnia, as 1 to 12. From the dis- crepancies in the prime number for brucia, de- duced from the above analyses, we see that its true equivalent remains to be determined. See Journal de Pharmacie, Dec. 1819. BRUCITE, or CONDR9DITE. This mineral occurs massive and in small grains, crossed by nearly parallel refts. Colour, wine, or wax-yellow; translucent; scratches glass with ease, and yields to the knife with diffi- culty. Sp. gr. 3.22, 3.55. By rubbing, it becomes negatively electric. It consists of magnesia 54, silica 38, oxide of iron 5.1, alumina 1.5, potash 0.86, manganese a trace. Count d? Ohsson . In the North Ameri can spe- cimen, fluoric acid has been found to the BUT 240 BYS amount of 4 per cent. It is found at Pargas, in Finland, and at Sparta, in New Jersey- BRUNSWICK GREEN. This is an ammoniaco-muriate of copper, much used for paper-hangings, and on the continent in oil painting. See COPPER. BUCHOLZITE. This mineral is amor- phous, spotted with white and black. Lustre glistening. Texture fibrous. It scratches glass, but is scratched by quartz. Its constituents are, silica 46, alumina 50, potash 1.5, oxide of iron, 2.5. Brandes. It is found in the Tyrol. BUCKLANDITE. This mineral has hi- therto been ranked with the pyroxenes, to which it has a great resemblance in form and external characters. Colour of the crystals, ^^ brown, nearly black, and opaque. They easily scratch glass, and seem harder than pyroxene. The forms of the crystals may be derived from an oblique rhombic prism Mr. Levy in An- nals of Philosophy, A". S. vii. 134. BUNTKUPFERERZ. Purple copper ore. BUTTER. The oily inflammable part of I ' milk, which is prepared in many countries as an article of food. The common mode of pre- serving it is by the addition of salt, which will keep it good a considerable time, if in sufficient quantity. Mr. Eaton informs us, in his Survey of the Turkish Empire, that most of the butter used at Constantinople is brought from the Crimea and Kirban, and that it is kept sweet, by melting it while fresh over a very slow fire, and removing the scum as it rises. He adds, that by melting butter in the Tartarian manner, and then salting it in ours, he kept it good and fine-tasted for two years ; and that this melt- ing, if carefully done, injures neither the taste nor colour. Thenard, too, recommends the Tartarian method. He directs the melting to be done on a water-bath, or at a heat not ex- ceeding 180 Fahr. ; and to be continued till all the caseous matter has subsided to the bot- tom, and tiie butter is transparent. It is then to be>decanted, or strained through a cloth, and cooled in a mixture of pounded ice and salt, or at least in cold spring water, otherwise it will become lumpy by crystallizing, and likewise not resist the action of the air so well. Kept in a close vessel, and in a cool place, it will thus remain six months or more, nearly as good as at first, particularly after the top is taken oft'. If beaten up with one-sixth of its weight of the cheesy matter when used, it will in some degree resemble fresh butter in appear- ance. The taste of rancid butter, he adds, may be much corrected by melting and cooling in this manner. Dr. Anderson has recommended another mode of curing butter, which is as follows : Take one part of sugar, one of nitre, and two of the best Spanish great salt, and rub them together into a fine powder. This composi- tion is to be mixed thoroughly with the butter, as soon as it is completely freed from the milk, in the proportion of one ounce to sixteen ; and the butter thus prepared is to be pressed tight into the vessel prepared for it, so as to leave no vacuities. This butter does not taste well, till it has stood at least a fortnight ; it then has a rich marrow flavour, that no other butter ever acquires ; and with proper care may be kept for years in this climate, or carried to the East Indies, if packed so as not to melt. In the interior parts of Africa, Mr. Park in- forms us, there is a tree much resembling the American oak, producing a nut in appearance somewhat like an olive. The kernel of this nut, by boiling in water, affords a kind of butter, which is whiter, firmer, and of a richer flavour, than any he ever tasted made from cows' milk, and will keep without salt the whole year. The natives call it shea toulou, or tree butter. Large quantities of it are made every season. BUTTER OF ANTIMONY. See Ay- TIAIONY. BUTTER OF CACAO. An oily con- crete white matter, of a firmer consistence than suet, obtained from the cacao nut, of which chocolate is made. The method of separating it consists in bruising the cacao and boiling it in water. The greater part of the super- abundant and uncombined oil contained in the nut is by this means liquefied, and rises to the surface, where it swims, and is left to congeal, that it may be the more easily taken off. It is generally mixed with small pieces of the nut, from which it may be purified, by keeping it in fusion without water in a pretty deep vessel, until the several matters have arranged them- selves according to their specific gravities. By this treatment it becomes very pure and white. Butter of cacao is without smell, and has a very mild taste, when fresh ; and in all its ge- neral properties and habitudes it resembles fat oils, among which it must therefore be classed. It is used as an ingredient in pomatums. BUTTER or TIN. See TIN. BYSSOLITE. A massive mineral, in short and somewhat stiff filaments, of an olive- green colour, implanted perpendicularly like moss, on the surface of certain stones. It has been found at the foot of Mont Blanc, and also near Oisans on gneiss. CAD 241 CAD CABBAGE (RED). See BRASSICA RUBRA. CACAO (BUTTER OF). SeeBuTTER. CACHOLONG. A variety of quartz. It is opaque, dull on the surface, internally of a pearly lustre, brittle, with a flat con- choidal fracture, and harder than opal. Its colour is milk-white, yellowish, or greyish- white. It is not fusible before the blowpipe. Its sp. grav. is about 2.2. It is found in de- tached masses on the river Cach in Bucharia, in the trap rocks of Iceland, in Greenland, and the Feroe Islands. According to Brog- niart, cacholongs are found also at Champigny near Paris, in the cavities of a calcareous breccia, some of which are hard and have a shining fracture, while others are tender, light, adhere to the tongue, and resemble chalk. CADMIUM. A new metal first discovered by M. Strom eyer, in the autumn of 1817, in some carbonate of zinc which he was examining in Hanover. It has been since found in the Derbyshire silicates of zinc. The following is Dr. Wollaston's process for procuring cadmium. It is distinguished by the usual elegance and precision of the analytical methods of this philosopher. From the solution of the salt of zinc supposed to contain cadmium, precipitate all the other metallic impurities by iron; filter and im- merse a cylinder of zinc into the clear solution. If cadmium be present, it will be thrown down in the metallic state, and when redissolved in muriatic acid, will exhibit its peculiar cha- racter on the application of the proper tests. M. Stromeyer's process consists in dissolving the substance which contains cadmium in sul- phuric acid, and passing through the acidulous solution a current of sulphuretted hydrogen gas. He washes this precipitate, dissolves it in concentrated muriatic acid, and expels the excess of acid by evaporation. The residue is then dissolved in water, and precipitated by carbonate of ammonia, of which an excess is added, to redissolve the zinc and the copper that may have been precipitated by the sul- phuretted hydrogen gas. The carbonate of cadmium being well washed, is heated, to drive off the carbonic acid, and the remaining oxide is reduced by mixing it with lamp- black, and exposing it to a moderate red heat in a glass or earthen retort. The colour of cadmium is a fine white, with a slight shade of bluish-grey, approaching much to that of tin ; which metal it resembles in lustre and susceptibility of polish. Its texture is compact, and its fracture hackly. It crystallizes easily in octohedrons, and pre- sents on its surface, when cooling, the appear- ance of leaves of fern. It is flexible, and yields readily to the knife. It is harder and more tenacious than tin ; and, like it, stains paper, or the fingers. It is ductile and mal- leable, but when long hammered, it scales off in different places. Its sp. grav. before ham. mering, is 8.6040; and when Hammered, it is 8-6944. It melts, and is volatilized under a red heat. Its vapour, which has no smell, may be condensed in drops like mercury, which, on congealing, present distinct traces of crystallization. Cadmium is as little altered by exposure to the air as tin. When heated in the open air, it burns like that metal, passing into a smoke, which falls and forms a very fixed oxide, of a brownish- yellow colour. Nitric acid readily dissolves it cold; dilute sulphuric, muriatic, and even acetic acids, act feebly on it with the disengagement of hydrogen. The solutions are colourless, and are not precipitated by water. Cadmium forms a single oxide, in which 100 parts of the metal are combined with 14-352 of oxygen. The prime equivalent of cadmium deduced from this compound seems to be very nearly 7, and that of the oxide 8. This oxide varies in its appearance according to circumstances from a brownish -yellow to a dark brown, and even a blackish colour. With charcoal it is reduced with rapidity below a red heat. It gives a transparent colourless glass bead with borax. It is insoluble in water, but in some circumstances forms a white hydrate, which speedily attracts carbonic acid from the air, and gives out its water when ex- posed to heat. The fixed alkalis do not dissolve the oxide of cadmium in a sensible degree ; but liquid ammonia readily dissolves it. On evaporating the solution, the oxide falls in a dense gelati- nous hydrate. With the acids it forms salts, which are almost all colourless, have a sharp metallic taste, are generally soluble in water, and possess the following characters : 1. The fixed alkalis precipitate the oxide in the state of a white hydrate. When added in excess, they do not redissolve the precipitate, as is the case with the oxide of zinc. 2. Ammonia likewise precipitates the oxide white, and doubtless in the state of hydrate ; but an excess of the alkali immediately re- dissolves the precipitate. 3. The alkaline carbonates produce a white precipitate, which is an anhydrous carbonate. Zinc in the same circumstances gives a hydrous carbonate. The precipitate formed by the carbonate of ammonia is not soluble in an ex- cess of this solution. Zinc exhibits quite dif- ferent properties. CAD CAD 4. Phosphate of soda exhibits a white pul- verulent precipitate. The precipitate formed by the same salt in solutions of zinc, is in fine crystalline plates. 5. Sulphuretted hydrogen gas, and the hy- drosulphurets, precipitate cadmium yellow or orange. This precipitate resembles orpiment a little in colour, with which it might be con- founded without sufficient attention. But it may be distinguished by being more pulveru- lent, and precipitating more rapidly. It differs particularly in its easy solubility in muriatic acid, and in its fixity. 6. Ferroprussiate of potash precipitates so- lutions of cadmium white. 7. Nutgalls do not occasion any change. 8. Zinc precipitates cadmium in the me- tallic state in the form of dendritical leaves, which attach themselves to the zinc. The carbonate consists, by Stromeyer, of Acid, 100.00 25.4 2.750 Oxide 292.88 74.6 8-054 The sulphate crystallizes in large rectangular transparent prisms, similar to sulphate of zinc, :wid very soluble in water. It effloresces in the air. At a strong red heat it gives out a portion of its acid, and becomes a subsulphate, which crystallizes in plates that dissolve with difficulty in water. The neutral sulphate con- sists of, Acid, 100.00 38.3 5.000 Oxide, 161.12 61-7 8.056 100 parts of the salt take 34.26 of water of crystallization. Nitrate of cadmium crystal- lizes in prisms or needles, usually grouped in rays. It is deliquescent. Its constituents are, Acid, 100.00 46 6-75000 Oxide, 117-58 54 7-93665 100 parts of the dry salt take 28.31 water of crystallization. The muriate of cadmium crystallizes in small rectangular prisms, per- fectly transparent, which effloresce easily when heated, and which are very soluble. It melts tinder a red heat, loses its water of crystalliza- tion, and on cooling assumes the form of a foliated mass, which is transparent, and has a lustre slightly metallic and pearly. In the air it speedily loses its transparency, and falls down in a white powder. 100 parts of fused chloride are composed of, Cadmium, 61.39 7.076 Chlorine, 58.61 4.450 Phosphate of cadmium is pulverulent, . in- soluble in water, and melts, when heated to redness, into a transparent vitreous body. It is composed of, Acid, 100 3.54 Oxide, 225.49 8.00 Borate of cadmium is scarcely soluble in water. It consists of, Acid, 27.88 3.079 Oxide, 72.12 8.000 Acetate of cadmium crystallizes in small prisms, usually disposed in stars, which are not altered by exposure to air, and are very soluble in water. The tartrate crystallizes in small scarcely soluble needles. The oxalate is insoluble. The citrate forms a crystalline powder, very little soluble. 100 parts of cadmium unite with 28.172 of sulphur, to form a sulphuret of a yellow colour, with a shade of orange. It is very fixed in the fire. It melts at a white red heat, and on cooling, crystallizes in micaceous plates of the finest leiron-yellow colour. The sulphuret dissolves even cold in concentrated muriatic acid, with the disengagement of sulphuretted hydrogen gas ; but the dilute acid has little effect on it, even with the assistance of heat. It is best formed by heating together a mix- ture of sulphur with the oxide, or by precipi- tating a salt of cadmium with sulphuretted hydrogen. It promises to be useful in painting. Phosphuret of cadmium, made by fusing the ingredients together, has a grey colour, and a lustre feebly metallic. Muriatic acid decomposes it, evolving phosphuretted hydro- gen gas. Iodine unites with cadmium, both in the moist and dry way. We obtain an iodide in large and beautiful hexahedral tables. These crystals are colourless, transparent, and not altered by exposure to air. Their lustre is pearly, approaching to metallic. It melts with extreme facility, and assumes, on cooling, the original form. At a high temperature, it is resolved into cadmium and iodine. Water and alcohol dissolve it with facility. It is composed of Cadmium, 100.00 7.000 Iodine, 227-43 15.9 Cadmium unites easily with most of the metals, when heated along with them out of contact of air. Most of its alloys are brittle and colourless. That of copper and cadmium is white, with a slight tinge of yellow. Its texture is composed of very fine plates, yi^ of cadmium communicates a good deal of brittleness to copper. At a strong heat the cadmium flies off. Tutty usually contains oxide of cadmium. The alloy consists of, Copper, 100 Cadmium, 84.2 The alloy of cobalt and cadmium has a good deal of resemblance to arsenical cobalt. Its colour is almost silver-white. 100 parts of platinum combine with 117.3 of cadmium. Cadmium and mercury readily unite cold, into a fine silver-white amalgam, of a granular texture, which may be crystallized in octo- hedrons. Its specific gravity is greater than that of mercury. It fuses at 167 F. It con- sists of, Mercury, 100 Cadmium, 27.78 Dr. Clarke found in 100 gr. of the fibrous silicate of zinc, of Derbyshire, about 6-10ths of a grain of sulphuret of cadmium ; a result which agrees with the experiments of Dr. Wollaston and Mr. Children. CAP 243 CAL Mr. W. Herapath states, that he has ob- tained cadmium in abundance from the zinc works near Bristol. Zinc is obtained by putting calamine with small coal into a cruci- ble, which being closed at top, has a tube proceeding through its bottom into a vault below. Beneath the tube is a vessel of water. A short tube is at hand to connect, at a proper time, with the long one, so as almost to reach the water. The workmen do not complete the connexion till the " brown blaze" is over, and the "blue blaze" begun. This brown flame is owing to cadmium, the oxide of which attaches itself to the roof of the vault, in greatest quantity, just over the orifice. It is mixed with soot, sulphuret of cadmium, and oxide of zinc. Some portions contain from 1 2 to 20 per cent, of cadmium. The metal is obtained by dissolving this substance in muriatic acid, filtering, evaporating to dryness, redissolving and filtering, then precipitating by a plate of zinc. The cadmium thrown down is to be mixed with a little lamp-black or wax, put into a black or green glass tube, and placed in the red heat of a common fire, until the cadmium has sublimed into the cool part of the tube ; then the residuum is to be shaken out, which is easily done without loss of cad- mium. A little wax introduced into the tube, and a gentle heat applied, the metal melts, and by agitation forms a button. Mr. Herapath thinks, that if the zinc smelter were to insert his tube earlier, and condense the first few pounds of metal sepa- rate, he would be able to collect abundance of cadmium, so as to afford it cheaply for the purposes of art. Ann. of Phil. iii. 435. CAFEIN. By adding muriate of tin to an infusion of unroasted coffee, M. Chenevix obtained a precipitate, which he washed and decomposed by sulphuretted hydrogen. The supernatant liquid contained a peculiar bitter principle, which occasioned a green precipitate in concentrated solutions of iron. When the liquid was evaporated to dryness, it was yellow and transparent, like horn. It did not attract moisture from the air, but was soluble in water and alcohol. The solution had a plea- sant bitter taste, and assumed with alkalis a garnet-red colour. It is almost as delicate a test of iron as infusion of galls is ; yet gelatine occasions no precipitate with it. M. Robiquet, while searching for quinina in coffee, discovered a crystallizable principle in it, in the year 1821- It is white, crystal- line, volatile, and slightly soluble. Its com- position is very remarkable, for according to MM. Dumas and Pelletier, it consists of Carbon 46.51 Nitrogen 21.54 Hydrogen 4.81 Oxygen 27.14 100.00 The quantity of nitrogen in it surpasses that not only in vegetable, but in most animal sub- stances; and must excite doubts as to the accuracy of the analysis. Ann. de Chim. xxiv. 183. CAJEPUT OIL. The volatile oil ob- tained from the leaves of the cajeput tree, Cajeputa officinarum, the Melaleuca Leuca- dendron of Linnaeus. The tree which fur- nishes the cajeput oil is frequent on the moun- tains of Amboyna, and other Molucca islands. It is obtained by distillation from the dried leaves of the smaller of two varieties. It is prepared in great quantities, especially in the island of Banda, and sent to Holland in cop- per flasks. As it comes to us, it is of a green colour, very limpid, lighter than water, of a strong smell resembling camphor, and a strong pungent taste, like that of cardamoms. It burns entirely away, without leaving any resi- duum. It is often adulterated with other essential oils, coloured with the resin of mil- foiL In the genuine oil, the green colour depends on the presence of copper ; for when rectified it is colourless. CALAMINE. A native carbonate of zinc. CALAMITE. A mineral which occurs in rhombic prisms of a light green colour, translucent, striated longitudinally, and yield- ing to mechanical division readily, parallel to the sides of a rhombic prism. It is soft ; re- sembling tremolite in the form of its crystal. It is found in serpentine with magnetic iron and calcareous spar, near Normark, in Sweden. Phillips' s Mineralogy. CALCAREOUS EARTH. See LIME. CALCAREOUS SPAR. Crystallized carbonate of lime. It occurs crystallized in more than 600 different forms, all having for then* primitive form an obtuse rhomboid, with angles of 74 55' and 105 5'. It occurs also massive, and in imitative shapes. Werner has given a comprehensive idea of the varieties of the crystals, by referring all the forms to the six-sided pyramid, the six-sided prism, and the three-sided prism, with their truncations. The colours of calc-spar are grey, yellow, red, green, and rarely blue. Vitreous lustre. Fo- liated fracture, with a threefold cleavage. Fragments rhomboidal. Transparent, or translucent. The transparent crystals refract double. It is less hard than fluor spar, and is easily broken. Sp. gr. 2.7 It consists of 43.6 carbonic acid, and 56.4 lime. It effer- vesces powerfully with acids. Some varieties are phosphorescent on hot coals. It is found in veins in all rocks, from granite to alluvial strata, and sometimes in strata between the beds of calcareous mountains. The rarest and most beautiful crystals are found in Derby- shire ; but it exists in every part of the world. CALCEDONY. A mineral so called from Calcedon in Asia Minor, where it was found in ancient times. There are several sub-species: common calcedony, heliotrope, R2 CAL 244 CAL ehrysoprase, plasma, onyx, sard, and sar- donyx. Common calcedony occurs in various shades of white, grey, yellow, brown, green, and blue. The blackish-brown appears, on look- ing through the mineral, to become a blood- red. It is found in nodules; botroidal sta- lactitical, bearing organic impressions, in veins, and also massive. Its fracture is even, some- times flat conchoidal, or fine splintery. Semi- transparent, harder and tougher than flint. Sp. grav. 2.6. It is not fusible. It may be regarded as pure silica, with a minute portion of water. Very fine stalactitical specimens have been found in Trevascus mine in Corn- wall. It occurs in the toadstone of Derby- shire, in the trap rocks of Fifeshire, of the Pentland-hills, Mull, Rum, Sky, and others of the Scottish Hebrides; likewise in Iceland, and the Ferro Islands. See the sub-species, under their respective titles. CALC SINTER. Stalactitical carbonate of lime. It is found in pendulous conical rods or tubes, mamellated, massive, and in many imitative shapes. Fracture lamellar, or diver- gent fibrous. Lustre silky or pearly. Colours white, of various shades, yellow, brown, rarely green, passing into blue or red. Translucent semihard very brittle. Large stalactites are found in the grotto of Antiparos, the wood- man's cave in the Hartz, the cave of Auxelle in France, in the cave of Castleton in Derby- shire, and Macalister cave in Sky. They are continually forming by the infiltration of car- bonated lime water, through the crevices of the roofs of caverns. Solid masses of stalac- tite have been called oriental alabaster. The irregular masses on the bottoms of caves have been called stalagmites. CALCHANTUM. Pliny's term for cop- peras. CALCINATION. The fixed residues of such matters as have undergone combustion are called cinders in common language, and calces, or now more commonly oxides, by chemists ; and the operation, when considered with regard to these residues, is termed calci- nation. In this general way it has likewise been applied to bodies not really combustible, but only deprived of some of their principles by heat. Thus we hear of the calcination of chalk, to convert it into lime, by driving off its carbonic acid and water : of gypsum or plaster stone, of alum, of borax, and other saline bodies, by which they are deprived of their water of crystallization ; of bones, which lose their volatile parts by this treatment ; and of various other bodies. See COMBUSTION and OXIDATION. CALCIUM. The metallic basis of lime. Sir H. Davy, the discoverer of this metal, procured it by the process which he used for obtaining barium ; which see. It was in such small quantities, that little could be said con- cerning its nature. It appeared brighter and whiter than either barium or strontium ; and burned when gently heated, producing dry lime. There is only one known combination of calcium and oxygen, which is the important substance called lime. The nature of this substance is proved by the phenomena of the combustion of calcium; the metal changing into the earth with the absorption of oxygen gas. When the amalgam of calcium is thrown into water, hydrogen gas is disengaged, and the water becomes a solution of lime. From the quantity of hydrogen evolved, compared with the quantity of lime formed in experi- ments of this kind, M. Berzelius endeavoured to ascertain the proportion of oxygen in lime. The nature of lime may also be proved by analysis. When potassium in vapour is sent through the earth ignited to whiteness, the potassium was found by Sir H. Davy to be- come potash, while a dark grey substance of metallic splendour, which is calcium, either wholly or partially deprived of oxygen, is found imbedded in the potash, for it effervesces violently, and forms a solution of lime by the action of water. Lime is usually obtained fore hemical pur- poses, from marble of the whitest kind, or from calcareous spar, by long exposure to a strong red heat. It is a soft white substance, of specific gravity 2.3. It requires an intense degree of heat for its fusion ; and has not hitherto been volatilized. Its taste is caustic, astringent and alkaline. It is soluble in 450 parts of water, according to Sir H. Davy ; and in 760 parts, according to other chemists. The solubility is not increased by heat. If a little water only be sprinkled on new burnt lime, it is rapidly absorbed, with the evolution of much heat and vapour. This constitutes the phenomenon called slaking. The heat proceeds, according to Dr. Black's explana- tion, from the consolidation of the liquid water into the lime, forming a hydrate, as slaked lime is now called. It is a compound of 3.5 parts of lime, with 1.125 of water; or very nearly 3 to 1. This water may be ex- pelled by a red heat, and therefore does not adhere to lime with the same energy as it does to barytes and strontites. Lime water is astringent and somewhat acrid to the taste. It renders vegetable blues green ; the yellows brown; and restores to reddened litmus its usual purple. When lime water stands ex- posed to the ah*, it gradually attracts carbonic acid, and becomes an insoluble carbonate, while the water remains pure. ' If lime water be placed in a capsule under an exhausted re- ceiver, which also encloses a saucer filled with concentrated sulphuric acid, the water will be gradually withdrawn from the lime, which will concrete into small six-sided prismatic crystals. Berzelius attempted to determine the prime equivalent of calcium, from the proportion in CAL 245 CAL which it combines with oxygen to form lime ; but his results can be regarded only as approx- imations, in consequence of the difficulties of the experiment. The prime equivalent of lime, or oxide of calcium, can be determined very exactly. 100 parts of carbonate of lime, consist of 44 carbonic acid + 56 lime ; whence the prime equivalent proportions are, 2-75 acid -(-3.5 base. If a piece of phosphorus be put into the sealed end of a glass tube, the middle part of which is filled with bits of lime about the size of peas ; and after the latter is ignited, if the former be driven through it in vapour, by heating the end of the tube, a compound of a dark brown colour, called phosphuret of lime, will be formed. This probably consists of 1.5 phosphorus -f- 2. 5 calcium ; but it has not been exactly analyzed. When thrown into water, phosphuretted hydrogen gas is disengaged in small bubbles, which explode hi succession as they burst. Sulphuret of lime is formed by fusing the constituents mixed together in a covered cru- cible. The mass is reddish coloured and very acrid. It deliquesces on exposure to air, and becomes of a greenish yellow hue. When it is put into water, a hydroguretted sulphuret of lime is immediately formed. The same liquid compound may be directly made, by boiling a mixture of sulphur and lime in water. It acts corrosively on animal bodies, and is a powerful reagent in precipitating metals from their solutions. Solid sulphuret of lime probably consists of 2 sulphur -|- 2.5 calcium. When lime is heated strongly in contact with chlorine, oxygen is expelled, and the chlorine is absorbed. For every two parts in volume of chlorine that disappear, one of oxygen is obtained. When liquid muriate of lime is evaporated to dryness, and ignited, it forms the same substance, or chloride of lime. It is a semitransparent crystalline substance ; fusible at a strong red heat; a nonconductor of electricity ; has a very bitter taste ; rapidly absorbs water from the atmosphere; and is extremely soluble in water. See ACID (Mu- RIATIC). It consists of 2.5 calcium -]- 4.5 chlorine = 7-0. Chlorine combines also with oxide of calcium or lime, forming the very important substance used in bleaching, under the name of oxymuriate of lime ; but which is more correctly called chloride of lime. See LIME, (CHLORIDE of). Under LIME, some observations will be found on the uses of this substance. If the liquid hydriodate of lime be evapo- rated to dryness, and gently heated, an iodide of calcium remains. It has not been applied to any use. CALCTUFF. An alluvial formation of carbonate of lime, probably deposited from calcareous springs. It has a yellowish-grey colour ; a dull lustre internally ^ a fine grained earthy fracture ; is opaque, and usually marked with impressions of vegetable matter. Its specific gravity is nearly the same with that of water. It is soft, and easily cut or broken. CALCULUS, or STONE. This name is generally given to all hard concretions, not bony, formed in the bodies of animals. Of these, the most important, as giving rise to one of the most painful diseases incident to human nature, is the urinary calculus, or stone in the bladder. Different substances occasionally enter into the composition of this calculus, but the most usual is the lithic acid. If we except Scheele's original observations concerning the uric or lithic acid, all the dis- coveries relating to urinary concretions are due to Dr. Wollaston ; discoveries so curious and important, as alone are sufficient to entitle him to the admiration and gratitude of mankind. They have been fully verified by the subse- quent researches of MM. Fourcroy, Vauquelin, and Brande, Drs. Henry, Marcet, and Prout. Dr. Marcet, in his late valuable essay on the chemical history and medical treatment of cal- culous disorders, arranges the concretions into nine species. 1. The lithic acid calculus. 2. The ammonia-magnesian phosphate cal- culus. 3. The bone earth calculus, or phosphate of lime. 4. The fusible calculus, a mixture of the 2d and 3d species. 5. The mulberry calculus, or oxalate of lime. 6. The cystic calculus ; cystic oxyde of Dr. Wollaston. 7. The alternating calculus, composed of alternate layers of different species. 8. The compound calculus, whose ingre- dients are so intimately mixed, as to be separa- ble only by chemical analysis. 9. Calculus from the prostate gland, which, by Dr. Wollaston's researches, is proved to be phosphate of lime, not distinctly stratified, and tinged by the secretion of the prostate gland. To the above Dr. Marcet has added two new sub-species. The first seems to have some resemblance to the cystic oxide, but it possesses also some marks of distinction. It forms a bright lemon-yellow residuum on evaporating its nitric acid solution, and is composed of laminae. But the cystic oxide is not laminated, and it leaves a white residuum from the nitric acid solution. Though they are both soluble in acids as well as alkalis, yet the oxide is more so in acids than the new calculus, which has been called by Dr. Marcet, from its yellow residuum, xanthic oxide. Dr. Marcet's other new calculus was found to possess the pro- perties of the fibrine of the blood, of which it seems to be a deposite. He terms iifibrinous calculus. Species 1. Uric acid calculi. Dr. Henry says, in his instructive paper on urinary and CAL 246 CAL other morbid concretions, read before the Me- dical Society of London, March 2, 1819, that it has never yet occurred to him to examine calculi composed of this acid in a state of ab- solute purity. They contain about 9-10ths of the pure acid, along with urea, and an animal matter which is not gelatine, but of an albu- minous nature. This must not, however, be regarded as a cement. The calculus is aggre- gated by the cohesive attraction of the lithic acid itself. The colour of lithic acid calculi is yellowish or reddish-brown, resembling the appearance of wood. They have commonly a smooth polished surface, a lamellar or radiated structure, and consist of fine particles well com- pacted. Their sp. gravity varies from 1.3 to 1.8. They dissolve in alkaline lixivia, without evolving an ammoniacal odour, and exhale the smell of horn before the blowpipe. The relative frequency of lithic acid calculi will be seen from the following statement. Of 150 examined by Mr. Brande, 16 were composed wholly of this acid, and almost all contained more or less of it. Fourcroy and Vauquelin found it in the greater number of 500 which they analyzed. All those examined by Scheele consisted of it alone ; and 300 analyzed by Dr. Pearson, contained it in greater or smaller proportion. According to Dr. Henry's expe- rience, it constitutes 1 urinary concretions out of 26, exclusive of the alternating calculi. And Mr. Brande lately states, that out of 58 cases of kidney calculi, 51 were lithic acid, 6 oxalic, and 1 cystic. Species 2. Ammonia-magnesian phosphate. This calculus is white like chalk, is friable between the fingers, is often covered with dog- tooth crystals, and contains semi-crystalline layers. It is insoluble in alkalis, but soluble in nitric, muriatic, and acetic acids. According to Dr. Henry, the earthy phosphates, com- prehending the 2d and 3d species, were to the whole number of concretions, in the ratio of 10 to 85. Mr. Brande justly observes, in the 16th number of his Journal, that the urine has at all times a tendency to deposit the triple phosphate upon any body over which it passes. Hence drains by which urine is carried off, are often incrusted with its regular crystals ; and in cases where extraneous bodies have got into the bladder, they have often in a very short time become considerably enlarged by deposi- tion of the same substance. When this calculus, or those incrusted with its semi-crystalline particles, are strongly heated before the blow- pipe, ammonia is evolved, and an imperfect fusion takes place. When a little of the calcareous phosphate is present, however, the concretion readily fuses. Calculi composed entirely of the ammonia-magnesian phosphate are very rare. Mr. Brande has seen only two. They were crystallized upon the surface, and their fracture was somewhat foliated. In its pure state, it is even rare as an incrustation. The powder of the ammonia-phosphate cal- culus has a brilliant white colour, a faint sweetish taste, and is somewhat soluble in water. Fourcroy and Vauquelin suppose the above deposites to result from incipient putre- faction of urine in the bladder. It is certain that the triple phosphate is copiously preci- pitated from urine in such circumstances out of the body. Species 3. The bone earth calculus. Its surface, according to Dr. Wollaston, is gene- rally pale brown, smooth, and when sawed through it appears of a laminated texture, easily separable into concentric crusts. Some- times, also, each lamina is striated in a di- rection perpendicular to the surface, as from an assemblage of crystalline needles. It is difficult to fuse this calculus by the blowpipe, but it dissolves readily in dilute muriatic acid, fretn which it is precipitable by ammonia. This species, as described by Fourcroy and Vau- quelin, was white, without lustre, friable, staining the hands, paper, and cloth. It had much of a chalky appearance, and broke under the forceps, and was intimately mixed with a gelatinous matter, which is left in a mem- branous form, when the earthy salt is withdrawn by dilute muriatic acid. Dr. Henry says that he has never been able to recognize a calculus of pure phosphate of lime, in any of the col- lections which he has examined ; nor did he ever find the preceding species in a pure state, though a calculus in Mr. White's collection contained more than 90 per cent, of ammonia- magnesian phosphate. Species 4. The fusible calculus. This is a very friable concretion, of a white colour, resembling chalk in appearance and texture ; it often breaks into layers, and exhibits glittering appearance internally, from inter- mixture of the crystals of triple phosphate. Sp. grav. from 1.14 to 1.47. Soluble in dilute muriatic and nitric acids, but not in alkaline lixivia. The nucleus is generally lithic acid. In 4 instances only out of 187, did Dr. Henry find the calculus composed throughout of the earthy phosphates. The analysis of fusible calculus is easily performed by distilled vinegar, which at a gentle heat dissolves the ammonia- magnesian phosphate, but not the phosphate of lime ; the latter may be taken up by dilute muriatic acid. The lithic acid present will remain, and may be recognized by its solu- bility in the water of pure potash or soda. Or the lithic acid may, in the first instance, be removed by the alkali, which expels the am- monia, and leaves the phosphate of magnesia and lime. Species 5. The mulberry calculus. Its surface is rough and tuberculated ; colour deep reddish-brown. Sometimes it is pale brown, of a crystalline texture, and covered with flat octahedral crystals. This calculus has com- monly the density and hardness of ivory, a sp. grav. from 1.4 to 1.98, and exhales the odour of semen when sawed. A moderate red heat CAL 247 CAL converts it into carbonate of lime. It does not dissolve in alkaline lixivia, but slowly and with difficulty in acids. When the oxalate of lime is voided directly after leaving the kidney, it is of a greyish-brown colour, composed of small cohering spherules, sometimes with a polished surface resembling hempseed. They are easily recognized by their insolubility in muriatic acid, and their swelling up and passing into pure lime before the blowpipe. Mulberry calculi contain always an admixture of other substances besides oxalate of lime. These are, uric acid, phosphate of lime, and animal mat- ter in dark fiocculi. The colouring matter of these calculi is probably effused blood. Dr. Henry rates the frequency of this species at 1 in 17 of the whole which he has compared ; and out of 187 calculi, he found that 17 were formed round nuclei of oxalate of lime. Species 6. The cystic-oxide calculus. It resembles a little the triple phosphate, or more exactly magnesian limestone. It is somewhat tough when cut, and has a peculiar greasy lustre. Its usual colour is pale brown, bor- dering on straw-yellow; and its texture is irregularly crystalline. It unites in solution with acids and alkalis, crystallizing with both. Alcohol precipitates it from nitric acid. It does not become red with nitric acid ; and it has no effect upon vegetable blues. Neither water, alcohol, nor ether dissolves it. It is decom- posed by heat into carbonate of ammonia and oil. leaving a minute residuum of phosphate of lime. This concretion is of very rare occur- rence. Dr. Henry states its frequency to the whole as 1 to 985. In two which he ex- amined, the nucleus was the same substance with the rest of the concretion ; and in a third, the nucleus of an uric acid calculus was a small spherule of cystic oxide. Hence, as Dr. Marcet has remarked, this oxide appears to be in reality the production of the kidneys, and not, as its name would import, to be generated in the bladder. It might be called with pro- priety renal oxide, if its eminent discoverer should think fit. Species 7. The alternating calculus. The surface of this calculus is usually white like chalk, and friable or semicrystalline, according as the exterior coat is the calcareous or ammo- nia-magnesian phosphate. They are frequently of a large size, and contain a nucleus of lithic acid. Sometimes the two phosphates form alternate layers round the nucleus. The above are the most common alternating calculi ; next are those of oxalate of lime with phosphates ; then oxalate of lime with lithic acid ; and, lastly, those in which the three substances alternate. The alternating, taken all together, occur in 10 out of 25, in Dr. Henry's list ; the lithic acid with phosphates, as 10 to 48 ; the oxalate of lime with phosphates, as 10 to 1 16 ; the oxalate of lime with lithic acid, as 10 to 170 ; the oxalate of lime with lithic acid and phosphates, as 10 to 265. Species 8. The compound calculus Tint consists of a mixture of lithic ncid with the phosphates in variable proportions, and is con- sequently variable in its appearance. Some, times the alternating layers are so thin as to be undistinguishable by the eye, when their nature can be determined only by chemical analysis. This species, in Dr. Henry's list, forms 1 in 235. About l-40th of the calculi examined by Fourcroy and Vauquelin were compound. Species 9. has been already described. In almost all calculi, a central nucleus may be discovered, sufficiently small to have de- scended through the ureters into the bladder. The disease of stone is to be considered, therefore, essentially and originally as be- longing to the kidneys. Its increase in the bladder may be occasioned, either by expo- sure to urine that contains an excess of the same ingredient as that composing the nucleus, in which case it will be uniformly constituted throughout ; or if the morbid nucleus deposite should cease, the concretion will then acquire a coating of the earthy phosphates. It be- comes, therefore, highly important to ascer- tain the nature of the most predominant nucleus. Out of 187 calculi examined by Dr. Henry, 17 were formed round nuclei of oxalate of lime ; 3 round nuclei of cystic oxide ; 4 round nuclei of the earthy phosphates ; 2 round extraneous substances ; and in 3 the nucleus was replaced by a small cavity, oc- casioned probably by the shrinking of some animal matter, round which the ingredients of the calculi (fusible) had been deposited. Kau has shown by experiment, that pus may form the nucleus of an urinary concretion. The remaining 158 calculi of Dr. Henry's list, had central nuclei composed chiefly of lithic acid. It appears, also, that in a very great majority of the cases referred to by him, the disposition to secrete an excess of lithic acid has been the essential cause of the origin of stone. Hence it becomes a matter of great importance to inquire, what are the circum- stances which contribute to its excessive pro- duction, and to ascertain by what plan of diet and medicine this morbid action of the kidneys may best be obviated or removed. A calculus in Mr. White's collection had for its nucleus a fragment of a bougie, that had slipped into the bladder. It belonged to the fusible spe- cies, consisting of, 20 phosphate of lime 60 ammonia-magnesian phosphate 10 lithic acid 10 animal matter 100 In some instances, though these are compara- tively very few, a morbid secretion of the earthy phosphates in excess, is the cause of the formation of stone. Dr. Henry relates the case of a gentleman, who, during paroxysms CAL CAL of gravel, preceded by severe sickness and vo- miting, voided urine as opaque as milk, which deposited a g^eat quantity of an impalpable powder, consisting of the calcareous and triple phosphate in nearly equal proportions. The weight of the body was rapidly reduced from 188 to 100 pounds, apparently by the ab- straction of the earth of his bones ; for there was no emaciation of the muscles correspond- ing to the above diminution. The first rational views on the treatment of calculous disorders, were given by Dr. Wollas- ton. These have been followed up lately by some very judicious observations of Mr. Brande in the 12th, 15th, and 16th numbers of his Journal ; and also by Dr. Marcet, in his ex- cellent treatise already referred to. Of the many substances contained in human urine, there are rarely more than three which constitute gravel ; viz. calcareous phosphate, ammonia-magnesian phosphate, and lithic acid. The former two form a white sediment ; the latter, a red or brown. The urine is always an acidulous secretion. Since by this excess of acid, the earthy salts, or white matter, are held in so- lution, whatever disorder of the system, or im- propriety of food and medicine, diminishes that acid excess, favours the formation of white deposite. The internal use of acids was shown by Dr. Wollaston to be the appropriate reme- dy in this case. White gravel is frequently symptomatic of disordered digestion, arising from excess in eating or drinking ; and it is often produced by too farinaceous a diet. It is also occasioned by the indiscreet use of magnesia, soda water, or alkaline medicines in general. Medical prac- titioners, as well as their patients, ignorant of chemistry, have often committed fatal mistakes, by considering the white gravel, passed on the administration of alkaline medicines, as the dis- solution of the calculus itself; and have hence pushed a practice, which has rapidly increased the size of the stone. Magnesia, in many cases, acts more injuriously than alkali, in precipi- tating insoluble phosphate from the urine. The acids of urine, which, by their excess, hold the earths in solution, are the phosphoric, lithic, and carbonic. Mr. Brande has uniformly ob- tained the latter acid, by placing urine under an exhausted receiver ; and he has formed car- bonate of barytes, by dropping barytes water into urine recently voided. The appearance of white sand does not seem deserving of much attention, where it is merely occasional, following indigestion brought on by an accidental excess. But if it invariably fol- lows meals, and if it be observed in the urine, not as a mere deposite, but at the time the last drops are voided, it becomes a matter of import- ance, as the forerunner of other and serious forms of the disorder. It has been sometimes viewed as the effect of irritable bladder, where it was in reality the cause. Acids are the pro- per remedy, and unless some peculiar tonic ef- fect be sought for in sulphuric acid, the vege- table acids ought to be preferred Tartar, or its acid, may be prescribed with advantage, but the best medicine is citric acid, in daily doses of from 5 to 30 grains. Persons return- ing from warm climates, with dyspeptic and hepatic disorders, often void this white gravel, for which they have recourse to empirical sol- vents, for the most part alkaline, and are deep- ly injured. They ought to adopt an acidulous diet, abstaining from soda water, alkalis, malt liquor, madeira and port ; to eat salads, with acid fruits ; and if habit requires it, a glass of cider, champagne or claret, but the less of these fermented liquors the better. An effervescing draught is often very beneficial, made by dis- solving 30 grains of bicarbonate of potash, and 20 of citric acid, in separate tea-cups of water, mixing the solution in a large tumbler, and drinking the whole during the effervescence. This dose may be repeated 3 or 4 times a-day. The carbonic acid of the above medicine enters the circulation, and passing offby the bladder, is useful in retaining, particularly, the triple phosphate in solution, as was first pointed out by Dr. Wollaston. The bowels should be kept regular by medicine and moderate exercise. The febrile affections of children are frequently attended by an apparently formidable deposite of white sand in the urine. A dose of calomel will generally carry off both the fever and the sand. Air, exercise, bark, bitters, mineral to- nics, are in like manner often successful in removing the urinary complaints of grown up persons. In considering the red gravel, it is necessary to distinguish between those cases in which the sand is actually voided, and those in which it is deposited, after some hours, from originally limpid urine. In the first, the sabulous ap- pearance is an alarming indication of a ten- dency to form calculi ; in the second, it is often merely a fleeting symptom of indigestion. Should it frequently recur, however, it is not to be disregarded. Bicarbonate of potash or soda is the proper remedy for the red sand, or lithic acid deposite. The alkali may often be beneficially combined with opium. Ammonia, or its crystallized car- bonate, may be resorted to with advantage, where symptoms of in digestion are brought on by the other alkalis ; and particularly in red gravel connected with gout, in which the joints and kidneys are affected by turns. Where potash and soda have been so long employed as to disagree with the stomach, to create nau- sea, flatulency, a sense of weight, pain, and other symptoms of indigestion, magnesia may be prescribed with the best effects. The ten- dency which it has to accumulate in dangerous quantities in the intestines, and to form a white sediment in urine, calls on the practitioner to look minutely after its administration. It should be occasionally alternated with other laxative medicines. Magnesia dissolved in car- CAL 249 CAL bonic acid, as Mr. Scheweppe used to prepare it many years ago, by the direction of Mr. Brande, is an elegant form of exhibiting this remedy. Care must be had not to push the alka- line medicines too far, lest they give rise to the deposition of earthy phosphates in the urine. Cases occur in which the sabulous deposite consists of a mixture of lithic acid with the phosphates. The sediment of urine in inflam- matory disorders is sometimes of this nature ; and of those persons who habitually indulge in excess of wine ; as also of those who, labour- ing under hepatic affections, secrete much albu- men in their urine. Purges, tonics, and nitric acid, which is the solvent of both the above sa- bulous matters, are the appropriate remedies. The best diet for .patients labouring under the lithic deposite, is a vegetable. Dr. Wollaston's fine observation, that the excrement of birds fed solely upon animal matter, is in a great mea- sure lithic acid, and the curious fact since as- certained, that the excrement of the boa con- strictor, fed also entirely on animals, is pure li- thic acid, concur in giving force to the above di- etetic prescription. A week's abstinence from animal food has been known to relieve a fit of lithic acid gravel, where the alkalis were of little avail. But we must not carry the vege- table system so far as to produce flatulency and indigestion. Such are the principal circumstances connect- ed with the disease of gravel in its incipient or sabulous state. The calculi formed in the kid- neys are, as we have said above, either lithic, oxalic, or cystic ; and very rarely indeed of the phosphate species. An aqueous regimen, mo- derate exercise on horseback when not accom- panied with much irritation, cold bathing, and mild aperients, along with the appropriate che- mical medicines, must be prescribed in kidney cases. These are particularly requisite imme- diately after acute pain in the region of the ureter, and inflammatory symptoms have led to the belief that a nucleus has descended into the bladder. Purges, diuretics, and diluents, ought to be liberally enjoined. A large quan. tity of mucus streaked with blood, or of a pu- rulent aspect, and haemorrhagy, are frequent symptoms of the passage of the stone into the bladder. When a stone has once lodged in the blad- der, and increased there to such a size as no longer to be capable of passing through the urethra, it is generally allowed by all who have candidly considered the subject, and who are qualified by experience to be judges, that the stone can never again be dissolved ; and al- though it is possible that it may become so loosened in its texture as to be voided piece- meal, or gradually to crumble away, the event is so rare as to be barely probable. By examining collections of calculi we learn, that in by far the greater number of cases, a nucleus of lithic acid is enveloped in a crust of the phosphates. Our endeavours must therefore be directed towards reducing the excess of lithic acid in the urine to its natural standard ; or, on the other hand, to lessen the tendency to the deposition of the phosphates. The urine must be submitted to chemical ex-> amination, and a suitable course of diet and medicines prescribed. But the chemical re- medies must be regulated nicely, so as to hit the happy equilibrium, in which no deposite will be formed. Here is a powerful call on physicians and surgeons to make themselves thoroughly versant hi chemical science ; for they will otherwise commit the most danger- ous blunders in calculous complaints. "The idea of dissolving a calculus of uric acid in the bladder, by the internal use of the caustic alkalis," says Mr. Brande, " appears too absurd to merit serious refutation." In respect to the phosphates, it seems possible, by keeping up an unusual acidity in the urine, so far to soften a crust of the calculus as to make it crumble down, or admit of being abraded by the sound ; but this is the utmost that can be looked for ; and the lithic nucleus will still remain. " These considerations," adds Mr. Brande, " independent of more urgent reasons, show the futility of attempting the solution of a stone of the bladder by the injection of acid and alkaline solutions. In respect to the al- kalis, if sufficiently strong to act upon the uric crust of the calculus, they would certainly in- jure the coats of the bladder ; they would otherwise become inactive by combination with the acids of the urine, and they would form a dangerous precipitate from the same cause." " It therefore appears to me, that Fourcroy and others, who have advised the plan of in- jection, have thought little of all these obstacles to success, and have regarded the bladder as a lifeless receptacle, into which, as into an India rubber bottle, almost any solvent might be injected with impunity." Journal of Science^ vol. viii. p. 210. It does not appear that the peculiarities of water in different districts have any influence upon the production of calculous disorders. Dr. Wollaston's discovery of the analogy be- tween urinary and gouty concretions has led to the trial in gravel of the mnum colchici, the specific for gout. By a note to Mr. Brande's dissertation we learn that benefit has been de- rived from it in a case of red gravel. Dr. Henry confirms the above precepts in the following decided language. " These cases, and others of the same kind, which I think it unnecessary to mention, tend to dis- courage all attempts to dissolve a stone sup- posed to consist of uric acid, after it has attained considerable size in the bladder ; all that can be effected under such circumstances by alkaline medicines appears, as Mr. Brande has remarked, to be the precipitating upon it a coating of the earthy phosphates from the CAL 250 CAL urine ; a sort of concretion which, as has been observed by various practical writers, increases much more rapidly than that consisting of uric acid only. The same unfavourable infer- ence may be drawn also from the dissections of those persons in whom a stone was supposed to be dissolved by alkaline medicines ; for in these instances it has been found either en- cysted, or placed out of the reach of the sound by an enlargement of the prostate gland. The urinary calculus of a dog, examined by Dr. Pearson, was found to consist principally of the phosphates of lime and ammonia, with animal matter. Several taken from horses were of a similar composition. One of a rab- bit consisted chiefly of carbonate of lime and animal matter, with perhaps a little phospho- ric acid. A quantity of sabulous matter, neither crystallized nor concrete, is sometimes found in the bladder of the horse : in one in- stance there were nearly 45 pounds. These appear to consist of carbonate of lime and ani- mal matter. A calculus of a cat gave Fourcroy three parts of carbonate and one of the phos- phate of lime. That of a pig, according to PBerthollet, was phosphate of lime. The renal calculus in man appears to be of the same nature as the urinary. In that of the horse, Fourcroy found three parts of carbonate and one of phosphate of lime. Dr. Pearson, in one instance, carbonate of lime and animal matter ; in two others, phosphates of lime and ammonia, with animal matter. Arthritic calculi, or those formed in the joints of gouty persons, were once supposed to be carbonate of lime, whence they were called chalkstones; afterward it was supposed that they were phosphate of lime ; but Dr. Wol- laston has shown that they are lithate of soda. The calculi found sometimes in the pinea], prostate, salivary, and bronchial glands, in the pancreas, in the corpora cavernosa penis, and between the muscles, as well as the tartar, as it is called, that incrusts the teeth, appear to be phosphate of lime. Dr. Crompton, how- ever, examined a calculus taken from the lungs of a deceased soldier, which consisted of lime 45, carbonic acid 37, albumen and water 18. It was very hard, irregularly spheroidal, and measured about 6^ inches in circumference. For the biliary calculi, see GALL. Those called lezoars have been already noticed under that article. It has been observed, that the lithic acid, which constitutes the chief part of most human urinary calculi, and abounds in the arthritic, has been found in no phytivorous animal ; and hence has been deduced a practical inference, that abstinence from animal food would pre- vent their formation. But we are inclined to think this conclusion too hasty. The cat is carnivorous ; but it appeared above, that the calculus of that animal is equally destitute of lithic acid. If, therefore, we would form any deduction with respect to regimen, we must look for something used by man, exclusively of all other animals; and this is obviously found in fermented liquors, but apparently in nothing else: and this practical inference is sanctioned by the most respectable medical authorities. The following valuable criteria, of the dif- ferent kinds of urinary calculi, have been given by M. Berzelius in his treatise on the use of the blowpipe. 1. We may recognize calculi formed of uric acid, from their being carbonized and smoking with an animal odour, when heated by themselves on charcoal or platinum-foil. They dwindle away at the blowpipe flame. Towards-the end, they burn with an increase of light ; and leave a small quantity of white very alkaline ashes. To distinguish these concretions from other substances, which comport themselves in the above manner, we must try a portion of the calculus by the humid way. Thus a tenth of a grain of this calculus being put on a thin plate of glass or platinum, along with a drop of nitric acid, we must heat it at the flame of the lamp. The uric acid dissolves with effer- vescence. The matter, when dried with pre- caution to prevent it from charring, is obtained in a fine red colour. If the calculus contains but little uric acid, the substance sometimes blackens by this process. We must theii take a new portion of the concretion, and after hav- ing dissolved it in nitric acid, remove it from the heat : the solution, when nearly dry, is to be allowed to cool and become dry. We then expose it, sticking to its support, to the warm vapour of caustic ammonia. (From water of ammonia heated in a tea-spoon). This ammo- niacal vapour develops a beautiful red colour in it. We may also moisten the dried matter with a little weak water of ammonia. If the concretions are a mixture of uric acid, and earthy phosphate, they carbonize and con- sume like the above, but their residuum is more bulky ; it is not alkaline, nor soluble in water. They exhibit, with nitric acid and am- monia, the fine red colour of uric acid. Their ashes contain phosphate of lime, or of lime and magnesia. 2. The calculi ofurate of soda are hardly met with except in the concretions round the articulations of gouty patients. When heated alone upon charcoal, they blacken, exhaling an empyreumatic animal odour ; they are with difficulty reduced into ashes, which are strongly alkaline, and are capable of vitrifying silica. When there are earthy salts (phosphates) in these concretions, they afford a whitish or opaque grey glass. 3. The calculi of nrate of ammonia com- port themselves at the blowpipe like those of uric acid. A drop of caustic potash makes them exhale, at a moderate heat, much ammo- nia. We must not confound this odour with the slight ammoniaco-lixivial smell, which pot- CAL 251 CAL ash disengages from the greater part of animal substances. Urate of soda is likewise found in these calculi. 4. Calculi of phosphate of lime. They blacken, with the exhalation of an ernpyreu- matic animal odour, without melting of them- selves at the blowpipe, but whiten into an evident calcareous phosphate. With soda they swell up without vitrifying. Dissolved in boracic acid, and fused along with a little iron, they yield a bead of phosphuret of iron. 5. Calculi of ammoniaco-magnesian phos- phate, heated alone on a plate of platinum, exhale the empyreumatic animal odour, at the same time blackening, swelling up, and becoming finally greyish-white. A kind of greyish-white enamel is in this manner ob- tained. With borax they melt into a glass, which is transparent, or which becomes of a milky- white on cooling. Soda in small quan- tity causes them to fuse into a frothy white slag ; a larger quantity of soda makes them infusible. They yield, with iron and boracic acid, a bead of phosphuret of iron : with ni- trate of cobalt, a glass of a deep red or brown. If salts of lime exist in these concretions, the mixture of them is less fusible. 6. Calculi of oxalate of lime, exposed to the blowpipe, exhale at first the urinous smell; they become first of a dull colour at the flame, and afterwards their colour brightens. What remains after a moderate ignition, effervesces with nitric acid. After a smart jet of the flame, there remains quicklime on the charcoal, which reacts like an alkali on the colour of litmus, wild mallow flower, or cabbage, and slakes with water. But this does not happen when the residuum consists of calcareous phos- phate. 7: The siliceous calculus, heated alone, leaves sub-coriaceous or infusible ashes. Treated with a little soda, these dissolve with effervescence, but slowly, leaving a bead of glass of a grey colour, or of little transparency. 8. Lastly, the cystic oxide calculi afford nearly the same results as uric acid at the blowpipe. They readily take fire, burning with a bluish-green flame, without melting, with the disengagement of a lively and very peculiar acid odour, which has some affinity to that of cyanogen. Their ashes, which are not alkaline, redissolve by a jet of the flame, into a greyish- white mass. They do not yield a red colour in their treatment with nitric acid, like the uric acid concretions. CALICO PRINTING ; the art of dyeing cloth (chiefly cotton and linen) topically ; that is, impressing figures, in one or more colours, on certain parts of the cloth, while the rest of the surface is left in its original state. See DYEING. CALOMEL. Chloride of mercury ; fre- quently called mild muriate of mercury ; and sometimes, but less properly, submuriate of mercury. See MERCURY. ON CALORIC. CALORIC. The agent to which the phenomena of heat and combustion are as- cribed. This is hypothetically regarded as a fluid, of inappreciable tenuity, whose particles are endowed with indefinite idio-repulsive powers, and which, by their distribution in various proportions among the particles of ponderable matter, modify cohesive attrac- tion, giving birth to the three general forms of gaseous, liquid, and solid. Many eminent philosophers, however, have doubted the separate entity of a calorific matter, and have adduced evidence to show that the phenomena might be rather referred to a vi- bratory or intestine motion of the particles of common matter. The most distinguished ad- vocate of this opinion in modern times is Sir H. Davy, the usual justness and profundity of whose views entitle them to deference. The following sketch of his ideas on this intricate subject, though it graduates perhaps into the poetry of science, cannot fail to increase our admiration of his genius, and to inculcate moderation on the partisans of the opposite doctrine. "Calorific repulsion has been accounted for, by supposing a subtile fluid capable of com- bining with bodies, and of separating their parts from each other, which has been named the matter of heat or caloric. " Many of the phenomena admit of a happy explanation on this idea, such as the cold pro- duced during the conversion of solids into fluids or gases, and the increase of temperature connected with the condensation of gases and fluids." In the former case we say the matter of heat is absorbed or combined, in the latter it is extruded or disengaged from combination. " But there are other facts which are not so easily reconciled to the opinion. Such are the production of heat by friction and percussion ; and some of the chemical changes which have been just referred to." These are, the violent heat produced in the explosion of gunpowder, where a large quantity of aeriform matter is disengaged ; and the fire which appears in the decomposition of the euchlorine gas, or pro- toxide of chlorine, though the resulting gases occupy a greater volume. " When the temperature of bodies is raised by friction, there seems to be no diminution of their capacities, using the word in its com- mon sense; and in many chemical changes, connected with an increase of temperature, there appears to be likewise an increase of capacity. A piece of iron made red-hot by hammering, cannot be strongly heated a second time by the same means, unless it has been previously introduced into a fire. This fact has been explained by supposing that the fluid of heat has been pressed out of it, by the per- cussion, which is recovered in the fire; but CAL 252 CAL this is a very rude mechanical idea : the ar- rangements of its parts are altered by hammer- ing in this way, and it is rendered brittle. By a moderate degree of friction, as would appear from Rumford's experiments, the same piece of metal may be kept hot for any length of time ; so that if heat be pressed out, the quantity must be inexhaustible. When any body is cooled, it occupies a smaller volume than before; it is evident therefore that its parts must have approached to each other : when the body is expanded by heat, it is equally evident that its parts must have se- parated from each other. The immediate cause of the phenomena of heat, then, is mo- tion, and the laws of its communication are precisely the same as the laws of the commu- nication of motion." " Since all matter may be made to fill a smaller volume by cooling, it is evident that the particles of matter must have space between them ; and since every body can communicate the power of expansion to a body of a lower temperature, that is, can give an expansive motion to its particles, it is a probable inference that its own particles are possessed of motion ; but as there is no change in the position of its parts as long as its temperature is uniform, the motion, if it exist, must be a vibratory or undulatory mo- tion, or a motion of the particles round their axes, or a motion of particles round each other. "It seems possible to account for all the phenomena of heat, if it be supposed that in solids the particles are in a constant state of vibratory motion, the particles of the hottest bodies moving with the greatest velocity, and through the greatest space ; that in liquids and elastic fluids, besides the vibratory motion, which must be conceived greatest in the last, the particles have a motion round their own axes, with different velocities, the particles of elastic fluids moving with the greatest, quickness; and that in ethereal substances," the particles move round their own axes, and separate from each other, penetrating in right lines through space. Temperature may be conceived to depend upon the velocities of the vibrations ; increase of capacity, on the motion being performed in greater space ; and the diminution of temperature, during the con- version of solids into fluids or gases, may be explained on the idea of the loss of vibratory motion, in consequence of the revolution of particles round their axes, at the moment when the body becomes liquid or aeriform ; or from the loss of rapidity of vibration, in consequence of the motion of the particles through greater space. " If a specific fluid of heat be admitted, it must be supposed liable to most of the af- fections which the particles of common matter are assumed to possess, to account for the phenomena ; such as losing its motion when combining with bodies, producing motion when transmitted from one body to another, and gaining projectile motion when passing into free space ; so that many hypotheses must be adopted to account for its agency, which renders this view of the subject less simple than the other. Very delicate experiments have been made, which show that bodies, when heated, do not increase in weight. This, as far as it goes, is an evidence against a subtile elastic fluid producing the calorific expansion ; but it cannot be considered as decisive, on ac- count of the imperfection of our instruments. A cubical inch of inflammable air requires a good balance to ascertain that it has any sen- sible weight, and a substance bearing the same relation to this, that this bears to platinum, could not perhaps be weighed by any method in our possession." It has been supposed, on the other hand, that the observations of Sir Wm. Herschel on the calorific rays which accompany those of light in the solar beam, afford decisive evi- dence of the materiality of caloric, or at least place the proof of its existence and that of light on the same foundation. That celebrated astronomer discovered, that when similar ther- mometers were placed in the different parts of the solar beam, decomposed by the prism into the primitive colours, they indicated different temperatures. He estimates the power of heating in the red rays, to be to that of the green rays, as 55 to 26, and to that of the violet rays as 55 to 16. And in a space beyond the red rays, where there is no visible light, the in- crease of temperature is greatest of all. Thus, a thermometer in the full red ray rose 7 Fahr. in ten minutes; beyond the confines of the coloured beam entirely, it rose in an equal time 9. These experiments were repeated by Sir H. Englefield with similar results. M. Berard, however, came to a somewhat different con- clusion. To render his experiments more certain, and their effects more sensible, this ingenious philosopher availed himself of the Jieliostat, an instrument by which the sunbeam can be steadily directed to one spot during the whole of its diurnal period. He decomposed by a prism the sunbeam, reflected from the mirror of the heliostat, and placed a sensible thermometer in each of the seven coloured rays. The calorific faculty was found to in- crease progressively from the violet to the red portion of the spectrum, in which the max- imum heat existed, and not beyond it, in the unilluminated space. The greatest rise in the thermometer took place while its bulb was still en tirely covered by the last red rays ; and it was observed progressively to sink as the bulb entered into the dark. Finally, on placing the bulb quite out of the visible spectrum, where Herschel fixed the maximum of heat, the elevation of its temperature above the ambient air was found, by M. Berard, to be only one-fifth of what it was in the extreme red ray. He afterwards made similar experi- CAL 253 CAL raents on the double spectrum produced by Island crystal, and also on polarized light, and he found in both cases that the calorific prin- ciple accompanied the luminous molecules ; and that in the positions where light ceased to be reflected, heat also disappeared. Newton has shown, that the different re- frangibility of the rays of light may be ex- plained by supposing them composed of par- ticles differing in size, the largest being at the red, and the smallest at the violet extremity of the spectrum. The same great man has put the query, Whether light and common matter are not convertible into each other ? and adopt- ing the idea, that the phenomena of sensible heat depend upon vibrations of the particles of bo- dies, supposes that a certain intensity of vi- brations may send off particles into free space ; and that particles in rapid motion in right lines, in losing their own motion, may com- municate a vibratory motion to the particles of terrestrial bodies. In this way we can rea- dily conceive how the red rays should impinge most forcibly, and therefore excite the greatest degree of heat. Enough has now been said to show how little room there is to pronounce dogmatic de- cisions on the abstract nature of heat. If the essence of the cause be still involved in mys- tery, many of its properties and effects have been ascertained, and skilfully applied to the cultivation of science and the uses of life. We shall consider them in the following order : ' 1. Of the measure of temperature. 2. Of the distribution of heat. 3. Of the general habitudes of heat with the different forms of matter. It will be convenient to make use of the popular language, and to speak of heat as ex- isting in bodies in greater or smaller quantities, without meaning thereby to decide on the ques- tion of its nature. 1. Of the measure of temperature. If a rod or ring of metal of considerable size, which is fitted to an oblong or circular guage in its ordinary state, be moderately heated, it will be found, on applying it to the cool guage, to have enlarged its dimen- sions. It is thus that coachmakers enlarge their strong iron rims, so as to make them embrace and firmly bind, by their retraction when cooled, the wooden frame work of their wheels. Ample experience has proved, that bodies, by being progressively heated, progressively ncrease in bulk. On this principle are con- structed the various instruments for measuring temperature. If the body selected for indi- cating, by its increase of bulk, the increase of heat, suffered equal expansions by equal in- crements of the calorific power, then the in- strument would be perfect, and we should have a just thermometer, or pyrometer. But it is very doubtful whether any substance, solid or liquid, preserves this equable relation between its increase of volume and increase of heat. The following quotation from a paper which the Royal Society did me the honour to publish in their Transac- tions for 1818, conveys my notions on this subject : "I think it indeed highly probable, that every species of matter, both solid and liquid, follows an increasing rate in its enlargement by caloric. Each portion that enters into a body must weaken the antagonist force, co- hesion, and must therefore render more effi- cacious the operation of the next portion that is introduced. Let 1000 represent the co- hesive attraction at the commencement, then, after receiving one increment of caloric, it will become 1000 1 = 999. Since the next unit of that divellent agent will have to com- bat only this diminished cohesive force, it will produce an effect greater than the first, in the proportion of 1000 to 999, and so on in con- tinued progression. That the increasing ratio is, however, greatly less than Mr. Dalton maintains, may, I think, be clearly demon- strated." P. 34. The chief object of the second chapter of that memoir, is the measure of temperature. The experiments, on which the reasoning of that part is founded, were made in the years 1812 and 1813, in the presence of many philosophical friends and pupils. By means of two admirable micrometer microscopes of Mr. Troughton's construction, attached to a peculiar pyrometer, I found that between the temperatures of melting ice, and the 540th degree Fahr., the apparent elongations of rods of pure copper and iron corresponded pari passu with the indications of two mercurial thermometers of singular nicety, made by Mr. Crighton, of Glasgow, compared with a very fine one of Mr. Troughton's. I consider the above results, and others contained in that same paper, as decisive against Mr. Dalton's hypothetical graduation of thermometers. They were obtained and detailed in public lectures many years before the elaborate researches of MM. Petit and Dulong on the same subject appeared ; and indeed the paper itself passed through Dr. Thomson's hands to London, many months before the excellent dissertation of the French philosophers was published. The researches of MM. Dulong and Petit are contained in the 7th volume of the Annales de Chimie et de Physique. They commence with some historical details, in which they observe, " that Mr. Dalton, considering this question from a point of view much more ele- vated, has endeavoured to establish general laws applicable to the measurement of all tem- peratures. These laws, it must be acknow- ledged, form an imposing whole by their re- gularity and simplicity. Unfortunately, this skilful philosopher proceeded with too much rapidity to generalize his very ingenious no- CAL 254 CAL tions, but which depended on uncertain data. The consequence is, that there is scarcely one of his assertions but what is contradicted by the result of the researches which we are now going to make known." M. Gay Lussac had previously shown, that between the limits of freezing and boiling water, a mercurial and an air thermometer did not present any sensible discordance. The following table of MM. Dulong and Petit gives the results from nearly the freezing to the boiling point of mercury. TABLE of Comparison of the Mercurial and Air Thermometer. Temperature indicated by the mercurial. Corresponding vols. of the same mass of air. Temperature indicated byan air ther- corrected for the dilatation of glass. Centigr. Fahr. Centigr. Fahr. -36o 100 150 200 250 300 Boiling, 360 32.80 +32 212 302 392 482 572 680 0.8650 1.0000 1.3750 1.5576 1.7389 1.9189 2.0976 2.3125 36.000 .00 100.00 148.70 197-05 245.05 292.70 350-00 32.8 +32.0 212.0 299.66 386.69 475.09 558.86 662.00 The well known uniformity in the principal physical properties of all the gases, and par- ticularly the perfect identity in the laws of their dilatation, render it very probable, that in this class of bodies the disturbing causes, to which I have adverted in my paper, have not the same influence as in solids and liquids ; and that consequently the changes in volume produced by the action of heat upon air and gases, are more immediately dependent upon the force which produces them. It is there- fore very probable, that the greatest number of the phenomena relating to heat will present themselves under a more simple form, if we measure the temperatures by an air thermo- meter. I coincide with these remarks of the French chemists, and think they were justified by such considerations to employ the scale of an air thermometer in their subsequent researches, which form the second part of their memoir on the laws of the communication of heat. The boiling point of mercury, according to MM. Dulorg and Petit, measured by a true thermometer, is 662 of Fahr. degrees. Now by Mr. Crighton's thermometer the boiling point is 656, a difference of only 6 in that prodigious range. Hence we see, as I pointed out in my paper, that there is a compensation produced between the unequable expansions of mercury and glass, and the lessening mass of mercury remaining in the bulb as the tem- peratures rise, whereby his thermometer be- comes a true measurer of the increments of sensible caloric. From all the experiments which have been made with care, we are safe in assuming the apparent expansion of mer- cury in glass to be l-63d pare of its volume on an average for every 1 80 Fahr. between 32 and 662, or through an interval of 7 times 90 degrees. Hence the apparent ex- pansion in glass for the whole is, -j^g- =: T *g- = ; 35 Fahr. Were the whole body of the thermometer, stem and bulb, immersed in boiling mercury, it would therefore indicate 35 more than it does when the bulb alone is immersed, or it would mark nearly 691 by Crighton. But the abstraction made of these 35, in conse- quence of the bulb alone being immersed in the heated liquids, brings back the common mercurial scale, when well executed, nearly to the absolute and just scale of an air ther- mometer, corrected for the expansions of the containing glass. The real temperature of boiling mercury by Dulong and Petit is 662 F. ; the apparent temperature, measured by mercury in glass, both heated to the boiling point of the former, is 680. But the latter is a false indication, and Mr. Crighton's compensated number 656 is very near the truth. We may therefore consider a well made mercurial thermometer as a sufficiently just measurer of temperature. For its construction and graduation, see THERMOMETER. 2. Of the distribution of heat. This head naturally divides into two parts ; first, the modes of distribution, or the laws of cooling, and the communication of heat among aeriform, liquid, and solid substances ; and, secondly, the specific heats of different bodies at the same and at different temperatures. The first views relative to the laws of the communication of heat are to be found in the Opusculaof Newton. This great philosopher assumes a priori, that a heated body exposed to a constant cooling cause, such as the uni- form action of a current of air, ought to lose at each instant a quantity of heat proportional to the excess of its temperature above that of the ambient air; and that consequently its CAL 255 CAL losses of heat in equal and successive portions of time, ought to form a decreasing geome- trical progression. Though Martin, in his Essays on Heat, pointed out long ago the in- accuracy of the preceding law, which indeed could not fail to strike any person, as it struck me forcibly the moment that I watched the progressive cooling of a sphere of oil which had been heated to the 500th degree, yet the proposition has been passed from one systema- tist to another without contradiction. Erxleben proved, by very accurate observa- tions, that the deviation of the supposed law increases more and more as we consider greater differences of temperatures; and concludes, that we should fall into very great errors if we extended the law much beyond the tempera- ture at which it has been verified. Yet Mr. Leslie since, in his ingenious researches on heat, has made this law the basis of several determinations, which from that very cause are regarded as inaccurate by Dulong and Petit. These gentlemen have investigated the true law in an able manner. When a body cools in vacua, its heat is entirely dissipated by radiation. When it is placed in air, or in any other fluid, its cool- ing becomes more rapid, the heat carried off by the fluid being irf that case added to that which is dissipated by radiation. It is natu- ral therefore to distinguish these two effects ; and as they are subject in all probability to different laws, they ought to be separately studied. MM. Dulong and Petit employed in this research mercurial thermometers, whose bulbs were from 0.8 of an inch to 2.6; the latter containing about three Ibs. of mercury. They found by preliminary trials, that the ratio of cooling was not affected by the size of the bulb, and that it held also in comparisons of mercury, with water, with absolute alcohol, and with sulphuric acid, through a range of temperature from 60 to 30 of the centigrade scale ; so that the ratio of the velocity of cool- ing between 60 and 50, and 40 and 30, was sensibly the same. On cooling water in a tin plate, and in a glass sphere, . they found the law of cooling to be more rapid in the former, at temperatures under the boiling point ; but by a very remarkable casualty, the contrary effect takes place in bodies heated to high tem- peratures, when the law of cooling in tin plates becomes least rapid. Hence, generally, that which cools by a most rapid law at the lower part of the scale, becomes the least rapid at high temperatures. " Mr. Leslie obtained such inaccurate re- sults respecting this question, because he did not make experiments on the cooling of bodies raised to high temperatures," say MM. Dulong and Petit, who terminate their preliminary re- searches by experiments on the cooling of water in three tin-plate vessels of the same capacity, the first of which was a sphere, the second and third cylinders ; from which we learn that the law of cooling is not affected by the difference of shape. The researches on cooling in a vacuum were made with an exhausted balloon; and a compensation was calculated for the mi- nute quantity of residuary gas. The fol- lowing series was obtained when the balloon was surrounded with ice. The degrees are centigrade. Excess of the therm, above the balloon. 240 220 200 180 160 140 120 100 80 Corresponding velocities of cooling. 10.69 8.81 7.40 6.10 489 3.88 3.02 2.30 1-74 The first column contains the excesses of temperature above the walls of the balloon; that is to say, the temperatures themselves, since the balloon was at 0. The second co- lumn contains the corresponding velocities of cooling, calculated and corrected. These ve- locities are the numbers of degrees that the thermometer would sink in a minute. The first series shows clearly the inaccuracy of the geometrical law of Richmann ; for according to that law, the velocity of cooling at 200 should be double of that at 100 ; whereas we find it as 7-4 to 2.3, or more than triple ; and in like manner, when we compare the loss of heat at 240 and at 80, we find the first about 6 times greater than the last ; while, according to the law of Richmann, it ought to be merely triple. From the above and some analogous experiments, the following law has been de- duced : When a body cools in vacuo, sur- rounded l>y a medium whose temperature is constant, the velocity of cooling for excess of temperature in arithmetical progression, in- creases as the terms of a geometrical pro- gression, diminished ly a certain quantity. Or, expressed in algebraic language, the fol- lowing equation contains the law of cooling in 9 t -vacuo: V=.m.a (a 1). 9 is the temperature of the substance sur- rounding the vacuum ; and t that of the heated body above the former. The ratio a of this progression is easily found for the thermome- ter, whose cooling is recorded above ; for when 9 augments by 20, t remaining ihe same, the velocity of cooling is then multiplied 1.165, which number is the mean of all the ratios ex- perimentally determined. We have then 20 a ,/ 1.165 = 1.0077. It only remains, in order to verify the ac- curacy of this law, to compare it with the different series, contained in the table in- CAL 256 CAL sorted above. In that case, in which the sur- rounding medium was 0, it is necessary to make m = 2.037, for m - and n is log. a an intermediate number; we have then V t = 2.037 (a - 1). Excesses of temp. Values of Values of V or value of t. V observed. calculated. 240 10.69 10.68 220 8.81 8.89 200 7.40 7.34 180 6.10 6.03 160 4.89 4.87 140 3.88 3.89 120 3.02 3.05 100 2,30 2.33 80 1.74 1.72 The laws of cooling in vacua being known, nothing is more simple than to separate from the total cooling of a body surrounded with air, or with any other gas, the portion of the effect due to the contact of the fluid. For this, it is obviously sufficient to subtract from the real velocities of cooling, those velocities which would take place if the body caeteris parilus were placed in vacua. This subtraction may be easily accomplished now that we have a formula, which represents this velocity with great precision, and for all possible cases. From numerous experimental comparisons the following law was deduced : The velocity of cooling of a body, owing to the sole contact of a gas, depends for the same excess of tem- perature, on the density and temperature of the fluid; but this dependence is such, that the velocity of cooling remains the same, if the density and the temperature of the gas change in such a way that the elasticity remains con- stant. If we call P the cooling power of air under the pressure p, this power will become P (1,366) under a pressure 2p; P (1.366) 2 under a pressure 4 p ; and under a pressure n n p' p 2 , it will be P (1.366). Hence -j- = fS_\ 0.45 P ' p/ x -j/ \ way for hydrogen, I _ ) P \ V / We shall find in the same 0.38 P For carbonic acid, the exponent will be 0.517, and for olefiant gas 0.501, while for air, as we see, it is 0.45. These last three numbers differing little from 0.5 or -^, we may say that in the aeriform bodies to which they belong, the cooling power is nearly as the square root of the elasticity. " If we com- pare the law which we have thus announced," say MM. Dulong and Petit, " with the ap- proximations of Leslie and Dalton, we shall be able to judge of the errors into which they have been led by the inaccurate suppositions which serve as the basis of all their calcula- tions, and by the little precision attainable by the methods which they have followed." But for these discussions, we must refer to the me- moir itself. The influence of the nature of the surface of bodies in the distribution of heat, was first accurately examined by Mr. Leslie. This branch of the subject is usually called the ra- diation of caloric. To measure the amount of this influence with precision, he contrived a peculiar instrument, called a differential ther- mometer. It consists of a glass tube, bent into the form of the letter U, terminated at each end with a bulb. The bore is about the size of that of large thermometers, and the bulbs have a diameter of i of an inch and upwards. Before hermetically closing the instrument, a small portion of sulphuric acid tinged with carmine is introduced. The adjustment of this liquid, so as to make it stand at the top of one of the stems, immediately below the bulb, re- quires dexterity in the operator. To this stem a scale divided ir.to 100 parts is attached, and the instrument is then fixed upright by a little cement on a wooden sole. If the finger, or any body wanner than the ambient air, be ap- plied to one of these bulbs, the air within will be heated, and will of course expand, and issu- ing in part from the bulb, depress before it the tinged liquor. The amount of this depression observed upon the scale, will denote the dif- ference of temperature of the two balls. But if the instrument be merely carried without touching either ball, from a warmer to a cooler, or from a cooler to a warmer air, or medium of any kind, it will not be affected ; because the equality of contraction or expansion in the enclosed air of both bulbs, will maintain the equilibrium of the liquid in the stem. Being thus independent of the fluctuations of the surrounding medium, it is well adapted to measure the calorific emanations of different surfaces, successively converged, by a concave reflector, upon one of its bulbs. Dr. Howard has described, in the IGth number of the Jour- nal of Science, a differential thermometer of his contrivance, which he conceives to possess some advantages. Its form is an imitation of Mr. Leslie's; but it contains merely tinged alcohol, or ether, the air being expelled by ebullition previous to the hermetical closure of the instrument. The vapour of ether, or of spirit in vacua, affords, he finds, a test of supe- rior delicacy to air. He makes the two legs of different lengths ; since it is in some cases very convenient to have the one bulb standing quite aloof from the other. In Mr. Leslie's, when they are on the same level, their distance asunder varies from of an inch to 1 or up- wards, according to the size of the instrument. The general length of the legs of the syphon is about 5 or 6 inches. His reflecting mirrors, of about 14 inches diameter, consisted of planished tin-platr, CAL 257 CAL hammered into a parabolical form by the guidance of a curvilinear gauge. A hollow tin vessel, 6 inches cube, was the usual source of calorific emanation in his experiments. He coated one of its sides with lamp-black, an- other with paper, a third with glass, and a fourth was left bare. Having then filled it with hot water, and set it in the line of the axis, and 4 or 6 feet in front of one of the mirrors, in whose focus the bulb of a differen- tial thermometer stood, he noted the depres- sion of the coloured liquid produced on pre- senting the different sides of the cube towards the mirror in succession. The following table gives a general view of the results, with these, and other coatings : Lamp-black, . Water by estimate, Writing paper, Rosin, Sealing wax, Crown glass, China ink, Ice, Red lead, Plumbago, Isinglass, Tarnished lead Mercury, Clean lead, Iron polished. Tin-plate, Gold, Silver, Copper, 100 100+ 98 90 95 90 88 85 80 75 75 45 20 + 19 15 12 12 Similar results were obtained by Leslie and Rumford in a simpler form. Vessels of similar shapes and capacities, but of different materials, were filled with hot liquids, and their rates of refrigeration noted. A blackened tin globe cooled a certain number of degrees in 81 mi- nutes ; while a bright one took nearly double the time, or 156 minutes ; a naked brass cy- linder in 55 minutes cooled ten degrees, while its fellow, cased in linen, was 36^ minutes in cooling the same quantity. If rapid motions be excited in the air, the difference of cooling between bright and dark metallic surfaces be- comes less manifest. Mr. Leslie estimates the diminution of effect from a radiating surface to be directly as its distance, so that double the distance gives one-half, and treble one-third of the primitive heating impression on thermome- ters and other bodies. Some of his experi- ments do not seem in accordance with this simple law. One would have expected cer- tainly, that, like light, electricity, and other qualities emanating from a centre, its diminu- tion of intensity would have been as the square of the distance; and particularly as Mr. Leslie found the usual analogy of the sine of inclina- tion to hold, in presenting the faces of the cube to the plane of the mirror under different an- gles of obliquity. Some practical lessons flow from the pre- ceding results. Since bright metals project heat most feebly, vessels which are intended to retain their heat, as tea and coffee-pots, should be made of bright and polished metals. Steam pipes intended to convey heat to a distant apartment, should be likewise bright in their course, but darkened when they reach their destination. By coating the bulb of his thermometer with different substances, Mr. Leslie inge- niously discovered the power of different sur- faces to absorb heat ; and he found this to fol- low the same order as the radiating or project- ing quality. The same film of silver leaf which obstructs the egress of heat from a body to those surrounding it, prevents it from receiving their calorific emanations in return. On this principle we can understand how a metallic mirror, placed before a fire, should scorch sub- stances in its focus, while itself remains cold ; and, on the other hand, how a mirror of dark- ened or even of silvered glass, should become intolerably hot to the touch while it throws little heat before it. From this absorbent faculty it comes that a thin pane of glass in- tercepts almost the whole heat of a blazing fire, while the light is scarcely diminished across it. By degrees indeed, itself becoming heated, constitutes a new focus of emanation, but still the energy of the fire is greatly inter- rupted. Hence also we see why the thinnest sheet of bright tin-foil is a perfect fire screen ; so impervious indeed to heat, that with a masque coated with it, our face may encounter without inconvenience the blaze of a glass- house furnace. Since absorption of heat goes hand in hand with radiation in the above table, we perceive that the inverse of absorption, that is reflec- tion, must be possessed in inverse powers by the different substances composing the list. Thus bright metals reflect most heat, and so on upwards in succession. Mr. Leslie is anxious to prove that elastic fluids, by their pulsatory undulations, are the media of the projection or radiation of heat ; and that therefore liquids, as well as a perfect vacuum, should obstruct the operation of this faculty. The laws of the cooling of bodies in vaCuo^ experimentally established by MM. Dulong and Petit, are fatal to Mr. Leslie's hypothesis, which indeed was not tenable against the numerous objections which had previously assailed it. The following beautiful experiment of Sir H. Davy seems alone to settle the question. He had an apparatus made, by which platina wire could be heated in any elastic medium or in vacua ; and by which the effects of radiation could be dis- tinctly exhibited by two mirrors, the heat being excited by a voltaic battery. In several experiments, in which the same powers were employed to produce the ignition, it was found that the temperature of a thermometer rose nearly three times as much in the focus of s CAL 258 CAL radiation, when the air in the receiver was ex- hausted to y^, as when it was in its natural state of condensation. The cooling power, by contact of the rarefied air, was much less than that of the air in its common state, for the glow of the platina was more intense in the first case than in the last ; and this circumstance perhaps renders the experiment not altogether decisive ; but the results seem favourable to the idea, that the terrestrial radiation of heat is not dependent upon any motions or affections of the atmosphere. The plane of the two mirrors was placed parallel to the horizon, the ignited body being in the focus of the upper, and the thermometer in that of the under mirror. It is evident that a diminished density of the elastic medium, amounting to -%-$, should, on Mr. Leslie's views, have occasioned a greatly diminished temperature in the inferior focus, and not a threefold increase, as happened; making every allowance for the diminished intensity of glow resulting from the cooling power of atmospheric air. The experiments with screens of glass, paper, &c. which Mr. Leslie adduced in support of his undulatory hypothesis, have been since confronted with the experiments on screens of Dr. Delaroche, who, by varying them, obtained results incom- patible with Mr. Leslie's views, and favourable to those on the intimate connexion between light and heat, with which our account of heat was prefaced. He shows that invisible radiant heat, in some circumstances, passes directly through glass, in a quantity so much greater relative to the whole radiation, as the tempe- rature of the source of heat is more elevated. The following table shows the ratio between the rays passing through clear glass, and the rays acting on the thermometer, when no screen was interposed, at successive temperatures. Temperature of the hot body in the focus. Rays transmit- ted through the glass screen. 655 10 800 10 1760 10 Argand's lamp without its chimney, 10 Ditto, with glass chim- ney, 10 Total Rays. 263 139 75 34 29 18 He next shows that the calorific rays which have already passed through a screen of glass, experience, in passing through a second glass screen of a similar nature, a much smaller di- minution of their intensity than they did in passing through the first screen ; and that the rays emitted by a hot body differ from each other in their faculty to pass through glass : that a thick glass, though as much as, or more permeable to light, than a thin glass of worse quality, allows a much smaller quantity of radiant heat to pass, the difference being so much the less the higher the temperature of the radiating source. This curious fact, that radiating heat becomes more and more capable of penetrating glass, as the temperature in- creases, till at a certain temperature the rays become luminous, leads to the notion that heat is nothing else than a modification of light, or that the two substances are capable of passing into each other. Dr. Delaroche's last pro- position is, that the quantity of heat which a hot body yields in a given time by radiation to a cold body situated at a distance, increases cteteris par'ibus in a greater ratio than the ex- cess of temperature of the first body above the second. For some additional facts on radiation, see LIGHT, to which subject, indeed, the whole discussion probably belongs. Even ice at 32, which appears so cold to the organs of touch, would become a focus of heat if transported into a chamber where the tem- perature of the air was at F. ; and a mass of melting ice placed before the mirror, would affect the bulb of the thermometer, just as the cube of heated water did. A mixture of snow and salt at 0, would in like manner become a warm body when carried into an atmosphere at 40. In all this, as well as in our sensa- tions, we see nothing absolute, nothing but mere differences. We are thus led to consider all bodies as projecting heat at every tempe- rature, but with unequal intensities, according to their nature, their surfaces, and their tem- perature. The constancy or steadiness of the temperature of a body will consist in the equality of the quantities of radiating caloric which it emits and receives in an equal time ; and the equality of temperature between several bodies which influence one another by their mutual radiation, will consist in the perfect compensation of the momentary interchanges effected among one and all. Such is the in- genious principle of a moveable equilibrium, proposed by Professor Prevost ; a principle whose application, directed with discretion, and combined with the properties peculiar to differ- ent surfaces, explains all the phenomena which we observe in the distribution of ra- diating caloric. Thus, when we put a ball of snow in the focus of one concave mirror, and a thermometer in that of an opposite mirror placed at some distance, we perceive the tem- perature instantly to fall, as if there were a real radiation of frigorific particles, according to the ancient notion. The true explanation is derived from the abstraction of that return of heat which the thermoscope mirror had pre- viously derived from the one now influenced by the snow, and now participating in its inferior radiating tension. Thus, also, a black body placed in the focus of one mirror, would di- minish the light in the focus of the other; and, as Sir H. Davy happily remarks, the eye is, to the rays producing light, a tneasnrc, similar to that which the thermometer is to rays producing heat. CAL 259 CAL This interchange of heat is finely exempli- fied in the relation which subsists between any portion of the sky and the temperature of the subjacent surface of the earth. In the year 1788, Mr. Six of Canterbury mentioned, in a paper transmitted to the Royal Society, that on clear and dewy nights he always found the mercury lower in a thermometer laid upon the ground, in a meadow in his neighbour- hood, than it was in a similar thermometer suspended in the air 6 feet above the former ; and that upon onenightthe difference amounted to 5 of Fahrenheit's scale. And Dr. Wells, in autumn 1811, on laying a thermometer upon grass wet with dew, and suspending a second in the air two feet above the surface, found in an hour afterwards, that the former stood 8 lower than the latter. He at first regarded this coldness of the surface to be the effect of the evaporation of the moisture, but sub- sequent observations and experiments con- vinced him, that the cold was not the effect but the cause of deposition of dew. Under a cloudless sky, the earth projects its heat without return, into empty space ; but a ca- nopy of cloud is a concave mirror, which re- stores the equilibrium by counter-radiation. See DEW. On this principle Dr. Wollaston suggested the construction of a pretty instrument, which Professor Leslie has called an /Ethrioscope, whose function it is, to denote the clearness and coolness of the sky. It consists of a po- lished metallic cup, of an oblong spheroidal shape, very like a silver porter-cup, standing upright, with the bulb of a differential ther- mometer placed in its axis, and the stem lying parallel to the stalk of the cup. The other ball is gilt, and turned outwards and upwards, so as to rest against the side of the vessel. The best form of the cup is an ellipsoid, whose eccentricity is equal to half the transverse axis, and the focus consequently placed at the third part of the whole height of the cavity; while the diameter of the thermoscope ball should be nearly the third part of the orifice of the cup. A lid of the same thin metal un- polished, is fitted to the mouth of the cup, and removed only when an observation is to be made. The scale attached to the stem of the thermoscope, may extend to 60 or 70 millesimal degrees above the zero, and about 15 degrees below it. This instrument, exposed to the open air in clear weather, will at all times, both during the day and the night, " indicate an impression of cold shot downward from the higher regions," in the figurative language of Mr. Leslie. Yet the effect varies exceedingly. It is greatest while the sky has the pure azure hue ; it di- minishes fast as the atmosphere becomes loaded with spreading clouds ; and it is almost extin- guished when low fogs settle on the surface. The liquid in the stem falls and rises with every passing cloud. Dr. Howard's modifi- cation of the thermoscope would answer well here. The diffusion of heat among the particles of fluids themselves, depends upon their specific gravity and specific heat conjunctly, and there- fore must vary for each particular substance. The mobility of the particles in a fluid, and their reciprocal independence on one another, permit them to change their places whenever they are expanded or contracted by alternations of temperature ; and hence the immediate and inevitable effect of communicating heat to the under stratum of a fluid mass, or of abstracting it from the upper stratum, is to determine a series of intestine movements. The colder particles, by their superior density, descend in a perpetual current, and force upwards those rarefied by the heat. When, however, the upper stratum primarily acquires an elevated temperature, it seems to have little power of imparting heat to the subjacent strata of fluid particles. Water may be kept long in ebul- lition at the surface of a vessel, v/hile the bottom remains ice cold, provided we take measures to prevent the heat passing down- wards through the sides of the vessel itself. Count Rumfbrd became so strongly persuaded of the impossibility of communicating heat downwards through fluid particles, that he re- garded them as utterly destitute of the faculty of transmitting that power from one to another, and capable of acquiring heat only in individual rotation, and directly from a foreign source. The proposition thus absolutely announced is absurd, for we know that by intermixture, and many other modes, fluid particles impart heat to each other ; and experiments have been in- stituted, which prove the actual descent of heat through fluids by communication from one stratum to another. But unquestionably this communication is amazingly difficult and slow. We are hence led to conceive, that it is an actual contact of particles, which in the solid condition facilitates the transmission of heat so speedily from point to point through their mass. This contact of certain poles in the molecules, is perfectly consistent with void spaces, in which these molecules may slide over each other in every direction ; by which movements or condensations heat may be excited. The fluid condition reverts or averts the touching and cohering poles, whence mobility results. This statement may be viewed either as a re- presentation of facts, or an hypothesis to aid conception. Since the diffusion of heat -through a fluid mass is accomplished almost solely by the in- testine currents, whatever obstructs these must obstruct the change of temperature. Hence fluids intermingled with porous matter, such as silk, wool, cotton, downs, fur, hair, starch, mucilage, &c. are more slowly cooled than in their pure and limpid state. Hence apple- tarts and pottages retain their heat very long, in comparison of the same bulk of water s2 ' CAL 260 CAL heated to the same degree, and exposed in similar covered vessels to die cool air. Of the conducting power of gaseous bodies, we have already taken a view. I know of no experiments which have satisfactorily deter- mined in numbers the relative conducting power of liquids. Mercury for a liquid pos- sesses a high conducting faculty, due to its density and metallic nature, and small specific heat. The transmission of heat through solids was made the subject of some pleasing popular ex- periments by Dr. Ingenhausz. He took a number of metallic rods of the same length and thickness, and having coated one of the ends of them for a few inches with bees' wax, he plunged their other ends into a heated liquid. The heat travelled onwards along the matter of each rod, and soon became mani- fest by the softening of the wax. The follow- ing is the order in which the wax melted ; and according to that experiment, therefore, the order of conducting power relative to heat. 1. Silver. 2. Gold. Platinum, "^ Iron, f much inferior to Steel, 4 the others. Lead, In my repetition of the experiment, I found silver by much the best conductor, next cop- per, then brass, iron, tin, much the same, then cast iron, next zinc, and last of all, lead. Dense stones follow metals in conducting power, then bricks, pottery, and at a long interval, glass. A rod of this singular body may be held in the fingers for a long time, at a distance of an inch from where it is ignited and fused by the blowpipe. It is owing to the inferior conducting power of stone, pottery, glass, and cast iron, that the sudden application of heat so readily cracks them. The part acted on by the caloric ex- pands, while the adjacent parts, retaining their pristine form and volume, do not accommodate themselves to the change; whence a fissure must necessarily ensue. Woods and bones are better conductors than glass ; but the pro- gress of heat in them at elevated temperatures, may be aided by the vaporization of their juices. Charcoal and saw-dust rank very low in conducting power. Hence the former is admirably fitted for arresting the dispersion of heat in metal furnaces. If the sides of these be formed of double plates, with an interval between them of an inch filled with pounded charcoal, an intense heat may exist within, while the outside is scarcely affected. Morveau has rated the conducting power of charcoal to that of fine sand, as 2 to 3, a difference much too small. Spongy organic substances, silk, wool, cotton, &c. are still worse conductors than any of the above substances ; and the finer the fibres, the less conducting power they possess. The theory of clothing depends on this principle. The heat generated by the animal powers, is accumulated round the body by the imperfect conductors of which clothing is composed. To discover the exact law of the distribu- tion of heat in solids, let us take a prismatic bar of iron, three feet long, and with a drill form three cavities in one of its sides, at 10, 20, and 30 inches from its end, each cavity capable of receiving a little mercury, and the small bulb of a delicate thermometer. Cut a hole fitting exactly the prismatic bar, in the middle of a sheet of tin-plate, which is then to be fixed to the bar, to screen it and the thermometers from the focus of heat. Im- merse the extremity of the bar obliquely into oil or mercury heated to any known degree, and place the thermometers in their cavities surrounded with a little mercury. Or the bar may be kept horizontal, if an inch or two at its end be incurvated, at right angles to its length. Call the thermometers A, B, C. Were there no dissipation of the heat, each thermometer would continue to mount till it attained the temperature of the source of heat. But, in actual experiments, projection and aerial currents modify that result, making the thermometers rise more slowly, and prevent- ing them from ever reaching the temperature of the end of the bar. Their state becomes indeed stationary whenever the excess of tem- perature, each instant communicated by the preceding section of the bar, merely compen- sates what they lose by the contact of the succeeding section of the bar, and the other outlets of heat. The three thermometers now indicate three steady temperatures, but in diminishing progression. In forming an equa- tion from the experimental results, M. La- place has shown, that the difficulties of the calculation can be removed only by admitting, that a determinate point is influenced not only by those points which touch it, but by others at a small distance before and behind it. Then the laws of homogeneity, to which differentials are subject, are re-established, and all the rules of the differential calculus are observed. Now, in order that the calorific influence may thus extend to a distance in the interior of the bar, there must operate through the very sub- stance of the solid,- elements a true radiation, analogous to that observed in air, but whose sensible influence is bounded to distances in- comparably smaller. This result is in no respect improbable. In fact, Newton has taught us, that all bodies, even the most opaque, become transparent when rendered sufficiently thin ; and the most exact researches on radiating caloric prove, that it does not emanate solely from the external surface of bodies, but also from material particles situated within this surface, becoming no doubt insen- CAL 261 CAL sible at a very slight depth, which probably varies in the same body with its temperature. MM. Biot, Fourier, and Poisson, three of the most eminent mathematicians and philo- sophers of the age, have distinguished them- selves in this abtruse investigation. The fol- lowing is the formula of M. Biot, when one end of the bar is maintained at a constant temperature, and the other is so remote as to make the influence of the source insensible. Let y represent, in degrees of the thermo- meter, the temperature of the air by which the bar is surrounded; let the temperature of the focus be y -f- Y ; then the integral becomes, log. y rr log. Y - / x is the distance from the hot end of the bar, a and b are two coefficients, supposed constant for the whole length of the bar, which serve to accommodate the formula to every possible case, and which must be assigned in each case, agreeably to two observations. M is the mo- dulus of the ordinary logc\rithmic tables, or the number 2.302585. M. Biot presents several tables of observations, in which some- times 8, and sometimes 14 thermometers, were applied all at once to successive points of the bar; and then he computes by the above formula what ought to be the tempera- ture of these successive points, having given the temperature of the source ; and vice versa, what should be the temperature of the source, from the indications of the thermometers. A perfect accordance is shown to exist between fact and theory. Whence we may regard the view opened up by the latter, as a true repre- sentation of the condition of the bar. With regard to the application of this theorem, to discover, for example, the temperature of a furnace, by thrusting the end of a thermoscopic iron bar into it, we must regret its insuffi- ciency. M. Biot himself, after showing its exact coincidence at all temperatures, up to that of melting lead, declares that it ought not to apply at high heats. But I see no diffi- culty in making a very useful instrument of this kind, by experiment, to give very valuable pyrometrical indications. The end of the bar which is to be exposed to the heat, being coated with fire-clay, or sheathed with pla- tinum, should be inserted a few inches into the flame, and drops of oil being put into three successive cavities of the bar, we should mea- sure the temperatures of the oil, when they have become stationary, and note the time elapsed to produce this effect A pyroscope of this kind could not fail to give useful information " to the practical chemist, as well as to manufacturers of glass, pottery, steel, &c. 2. Ofspecificheat.Ifvfe take equal weights, or equal bulks, of a scries of substances ; for example, a pound or a pint of water, oil, al- cohol, mercury, and having heated each, sepa- rately in a thin vessel, to the same tempera- ture, say to 80 or 100 Fahr. from an atmo- spherical temperature of 60, then in the sub- sequent cooling of these four bodies to their former state, they will communicate to sur- rounding media very different quantities of heat. And conversely, the quantity of heat requisite to raise the temperature ef equal masses of different bodies an equal number of therrnometric degrees, is different, but specific for each body. There is another point of view in which specific heats of bodies may be consi- dered relative to their change of form, from gaseous to liquid, and from liquid to solid. Thus the steam of water at 2 12, in becoming a liquid, does not change its thermometric temperature 212, yet it communicates, by this change, a vast quantity of heat to sur- rounding bodies ; and, in like manner, liquid water at 32, in becoming the solid called ice, does not change its temperature as measured by a thermometer, yet it imparts much heat to surrounding matter. We therefore divide the study of specific heats into two branches : 1. The specific heats of bodies while they re- tain the same state ; and 2. The specific heats, connected with, or developed by, change of state. The first has been commonly called the capacities of bodies for caloric ; the Second, the latent heat of bodies. The latter we shall consider after change of state. 1. Of the specific heats of bodies, while they experience no change of state. Three distinct experimental modes have been employed to determine the specific heats of bodies : in the whole of which modes, that of water has been adopted for the standard of comparison or unity. 1. In the Jirst mode, a given weight or bulk of the body to be ex- amined, being heated to a certain point, is suddenly mixed with a given weight or bulk of another body, at a different temperature ; and the resulting temperature of the mixture shows the relation between their specific heats. Hence, if the second body be water, or any other substance whose relation to water is as- certained, the relative heat of the first to that of water will be known. It is an essential precaution in using this mode, to avoid all such chemical action as happens in mixing water with alcohol or acids. Let us take oil for an example. If a pound of it, at 90 Fahr. be mixed with a pound of water at 60, the resulting temperature will not be the mean 75, but only 70. And conversely, if we mix a pound of water heated to 90, with a pound of oil at 60, the temperature of the mixture will be 80. We see here, that the water in the first case acquired 10, while the oil lost 20 ; and in the second case, that the water lost 10, while the oil gained 20. Hence we say, that the specific heat of water is double to that of oil, or that the same quan- tity or intensity of heat which will change the temperature of oil 20, will change that of CAL 262 CAL water only 10 ; and therefore, if the specific heat, or capacity for heat, of water be called 1.000, that of oil will be 0.500. When the experiment has been, from particular circum- stances, made with unequal weights, the ob- vious arithmetical reduction, for the difference, must be made. This is the original method of Black, Irvine, and Crawford. The second mode is in some respects a mo- dification of the first. The heated mass of the matter to be investigated, is so surrounded by a large quantity of the standard substance at an inferior temperature, that the whole heat evolved by the first, in cooling, is received by the second. We may refer to this mode, 1st, Wilcke's practice of suspending a lump of heated metal in the centre of a mass of cold water contained in a tin vessel : 2d, The plan of Lavoisier and Laplace, in which a heated mass of matter was placed by means of their elegant CALORIMETER, in the centre of a shell of ice ; and the specific heat was inferred from the quantity of ice that was liquefied : And 3d, The method of Berard and Delaroche, in which gaseous matter, heated to a known temperature, was made to traverse, slowly and uniformly, the convolutions of a spiral pipe, fixed in a cylinder of cool water, till this water rose to a stationary temperature ; when, *' reckoning from this point, the excess of the temperature of the cylinder above that of the ambient air, becomes proportional to the quan- tity of heat given out by the current of gas that passed through the cylinder." Each gas was definitely heated, by being passed through a straight narrow tube, placed in the axis of a large tube, filled with the steam of boiling water. The specific heats were then compared to water by two methods. The first consists in subjecting the cylinder, which they call the calorimeter, to the action of a current of water perfectly regular, and so slow, that it will hardly produce a greater effect than the current of the different gases. The second method consists in determining, by calculation, the real quantity of heat which the calorimeter, come to its stationary temperature, can lose in a given time ; for since, after it reaches this point, it does not become hotter, though the source of heat continues to be applied to it, it is evident that it loses as much heat as it receives. MM. Berard and Delaroche em- ployed these two methods in succession. From the singular ingenuity of their apparatus, and precision of their observations, we may regard their determinations as deserving a degree of confidence to which the previous results, on the specific heat of the gases, are not at all entitled. They have completely overturned the hypothetical structures of Black, Lavoisier, and Crawford, on the heat developed in com- bustion and respiration, while they give great countenance to the profound views of Sir H. Davy. See COMBUSTION, and APPENDIX. The third method of determining the spe cific heats of bodies, is by raising a given mass to a certain temperature, suspending it in a uniform cool medium, till it descends through a certain number of thermometric degrees, and carefully noting by a watch the time elapsed. It is evident, that if the bodies be invested with the same coating, for instance, glass or burnished metals; if they be sus- pended in the same medium, with the same excess of temperature; and if their interior constitution relative to the conduction of heat be also the same, then their specific heats will be directly as the times of cooling. I have tried this method, and find that it readily gives, in common cases, good approximations. Some of my results were published in the Annals of Phil, for October 1817, on water, sulphuric acid, spermaceti oil, and oil of tur- pentine. "A thin glass globe, capable of holding 1800 grains of water, was successively filled with this liquid, and with the others ; and being in each case heated to the same degree, was suspended, with a delicate ther- mometer immersed in it, in a large room of uniform temperature. The comparative times of cooling, through an equal range of the thermometrie scale, were carefully noted by a watch in each case." The difference of mo- bility in the liquid particles may be regarded as very trifling, at temperatures from 100 to 200. At inferior temperatures, under 80 for example, oil of vitriol, as well as sperma- ceti oil, becoming viscid, would introduce erroneous results. Another mode has been lately practised with the utmost scientific refinement by MM. Dulong and Petit. Their experiments were made on metals reduced to fine filings, strongly pressed into a cylindrical vessel of silver, very thin, very small, and the axis of which was occupied by the reservoir of the thermometer. This cylinder, containing about 460 grains of the substance, heated about 12 F. above the ambient medium, was suspended in the centre of a vessel blackened interiorly, surrounded with melting ice, and exhausted of air, to prolong the period of refrigeration, which lasted generally 15 minutes. Their results have disclosed a beautiful and unforeseen re- lation, between the specific heats and primitive combining ratios or atoms of the metals; namely, that the atoms of all simple oodles have exactly the same capacity for heat. Hence the specific heat of a simple substance, multiplied into the weight of its atom or prime equivalent, ought to give always the same product. The law of specific heats being thus estab- lished for elementary bodies, it became very important to examine, under the same point of view, the specific heats of compound bodies. Their process applying indifferently to all substances, whatever be their conductibility or state of aggregation, they had it in their power to subject to experiment a great many bodies. CAL 263 CAL whose proportions may be considered as fixed ; but when they endeavoured to mount from these determinations to that of the specific heat of each compound atom, by a method analogous to that employed for the simple bodies, they found themselves stopped by the number of equally probable suppositions among which they had to choose. " If the method," say they, " of fixing the weights of the atoms of simple bodies has not yet been subjected to any certain rule, that of the atoms of compound bodies has been, a fortiori, de- duced from suppositions purely arbitrary." They satisfy themselves by saying, in the mean time, that abstracting every particular supposition, the observations which they have hitherto made tend to establish this remark- able law. that there always exists a very simple ratio between the capacity for heat of the compound atoms, and that of the elementary atoms. We shall insert here tabular views of the specific heats determined by the recent re- searches of these French chemists, reserving, for the end of the volume, the usual more ex- tended, but less accurate tables of specific heat. MM. Petit and Dulong justly remark, that " the attempts hitherto made to discover some laws in the specific heats of bodies have been entirely unsuccessful. We shall not be surprised at this, if we attend to the great inaccuracy of some of the measurements ; for if we except those of Lavoisier and Laplace (unfortunately very few), and those by La- roche and Berard for elastic fluids, we are forced to admit, that the greatest part of the others are extremely inaccurate, as our own experiments have informed us, and as might indeed be concluded from the great discordance in the results obtained for the same bodies by different experimenters." From this censure we must except the recent results of MM. Clement and Desormes on gases, which I believe may be regarded as entitled to equal confidence with those of Berard and Delaroche. TABLE I. Of the specific Heats of Gases, by MM. BERARD and DELAROCHE. for atmospheric air. The experimenters have taken 0.2669 as the mean, to which all the above results are referred, as follows : TABLE II. Equal volumes. Equal weights. Sp. gravity. Air, Hydrogen, Carbonic acid, Oxygen, Azote, Oxide of azote, Olefiant gas, Carbonic oxide, 1.0000 0.9033 1.2583 0.9765 1.0000 1.3503 1.5530 1.0340 1.0000 12.3401 0.8280 0.8848 1.0318 0.8878 1.5763 1.0805 1.0000 0.0732 1.5196 1.1036 0.9691 1-5209 0.9885 0.9569 Water, Air, Hydrogen gas, Carbonic acid, Oxygen, Azote, Oxide of Azote, Olefiant gas, Carbonic oxide, Aqueous vapour, 1.0000 0.2669 3.2936 0.2210 0.2361 0.2754 0.2369 0.4207 0.2884 0.8470 4 To reduce the above numbers to the stan- dard of water, three different methods were employed; from which the three numbers, 0.2198, 0.2697, and 0.2813, were obtained The following are the results given by MM. Clement and Desormes, for equal volumes at temperatures from to 60 centigrade, or 32<>tol40<>Fahr. TABLE III. Inches Clement & Delaroche I iarom. Desormes. & Berard. Atmospheric air at 39.6 1.215 1.2396 Ditto 29.84 1.000 1.0000 Ditto 14.92 O.C93 Ditto 7-44 0.540 Ditto 3.74 0.368 Do. charged with ) ether, j 29.84 1.000 Azote, 29.84 1.000 1.0000 Oxygen, 29.84 1.000 0.974 Hydrogen, 29.84 0.664 , 0.9033 Carbonic acid, 29.84 1.500 1.2583 The relative specific heat of air to water is, by MM. Clement and Desormes, 0.250 to 1.000, or exactly one-fourth. The last table, which is extracted from the Journal de Phy- sique, gives the specific heat of oxygen by Delaroche and Berard, a little different from their own number, Table I. from the Annales de Chimie, vol. 85. The most remarkable re- sult given by MM. Clement and Desormes regards carbonic acid, which being reduced to the standard of weights, gives a specific heat compared to air of about 0.987 to 1.000, while oxygen is only 0.9000. The former tables of Crawford and Dalton give the sp. heat of oxygen 2.65, and of carbonic acid 0.586, com- pared to air 1.000. And upon these very erroneous numbers, they reared their hypo- thetical fabric of latent heat, combustion, and animal temperature. We shall refer to the above table in treating of combustion. We see from the experiments on air, at different densities, that its specific heat dimi. nishes in a much lower rate than its specific gravity. When air is expanded to a quadru- ple volume, its specific heat becomes 0.540, and when expanded to eight times the vo- CAL 264 CAL lume, its specific heat is 0.368. The densi- ties in the geometrical progression 1, ^, ^, >, correspond nearly to the specific heats in the arithmetical series 5, 4, 3, 2. Hence also the specific heat of atmospherical air, and of pro- bably all gases, considered in the ratio of its weight or mass, diminishes as the density in- creases. On the principle of the increase of specific heat, relative to its mass, has been ex- plained the long observed phenomenon of the intense cold which prevails on the tops of mountains, and generally in the upper regions of the atmosphere ; and also that of the pro- digious evolution of heat when air is forcibly condensed. According to M. Gay Lussac, a condensation of volume amounting to four- fifths, is sufficient to ignite tinder. If a sy- ringe of glass be used, a vivid flash of light is seen to accompany the condensation. TABLE IV Of Specific Heats of some Solids, determined ly DULONG and PETIT. Specific heats, that of water being 100. Weight of the atoms, oxygen be- ing 1. Product of these two num- bers. Bismuth, 0-0288 13-300 0-3830 Lead, 0-0293 12-950 0-3794 Gold, 0-0298 12-430 0-3704 Platinum, 0-0314 11-160 0-3740 Tin, 0-0514 7-350 0-3779 Silver, 0-0557 6-750 0-3759 Zinc, 0-0927 4-030 0-3736 Tellurium, 0-0912 4-030 0-3675 Copper, 0-0949 3-957 0-3755 Nickel, 0-1035 3-690 0-3819 Iron, 0-1100 3-392 0-3731 Cobalt, 0-1498 2-460 0-3685 Sulphur, 0-1880 2-011 0-3780 The above products, which express the capa- cities of the different atoms, approach so near to equality, that the slight differences must be owing to slight errors, either in the measure- ment of the capacities, or in the chemical ana- lyses, especially if we consider, that, in certain cases, these errors, derived from these two sources, may be on the same side, and conse- quently be found multiplied in the result. Kach atom of these simple bodies seems, there- fore, as was formerly stated, to have the same capacity for heat. An important question now occurs, whether the relative capacities for heat of different solid and liquid bodies be uniform at different tem- peratures, or whether it vary with the temper- ature ? This question may be perhaps more clearly expressed thus: Whether a body, in cooling a certain thermometric range at a high temperature, gives out the same quantity of heat that it does in cooling through the same range at a lower temperature ? No means seem better adapted for solving this problem, than to measure the refrigeration produced, by the same weights of ice, on uniform weights of water, at different temperatures. Mr. Dalton found in this way, that " 176.5 expresses the number of degrees of temperature, such as are found between 200 and 212 of the old or common scale, entering into ice of 32 to con- vert it into water of 32 ; 150 of the same scale, between 122 and 130, suffice for the same effect ; and between 45 and 50, 128 are adequate to the conversion of the same ice into water. These three resulting numbers (128, 150, 176.5) are nearly as 5, 6, 1. Hence it follows, that as much heat is neces- sary to raise water 5 in the lower part of the old scale, as is required to raise it 7 in the higher, and 6 in the middle." See Ms New System of Chemical Philos. vol. i. p. 53. Mr. Dalton, instead of adopting the obvious conclusion that the capacity of water for heat, is greater at lower than it is at higher temper- atures, and that therefore a smaller number of degrees at the former, should melt as much ice as a greater number at the latter, ascribes the deviation denoted by these numbers, 5, 6, and 7, to the gross errors of the ordinary thermo- metric graduation, which he considers so ex- cessive, as not only to equal, but greatly to overbalance the really increased specific heat or capacity of water ; which, viewed in itself, he conceives would have exhibited opposite experimental results. That our o/rf, and, ac- cording to his notions, obsolete thermometric scale, has no such prodigious deviation from truth, is, I believe, now fully admitted by chemical philosophers ; and therefore the only legitimate inference from these very experi- ments of Mr. Dalton, is the decreasing capa- city of water, with the increase of its tempera- ture. It deserves to be remarked, that my experiments on the relative times of cooling a globe of glass, successively filled with water, oil of vitriol, common oil, and oil of turpen- tine, give exactly the same results as Mr. Dal- ton had derived from mixtures of two ounces of ice with 60 of water, at different tempera- tures. This concurrence is the more satis- factory, since, when my paper on the specific heats of the above bodies, published in the Annals of Philosophy for October 1817, was written, I had no recollection of Mr. Dalton's experiments. TABLE V. Of Capacities for Heat. Mean capacity between and 100. Mean capacity be- tween and 3000. Mercury, 0-0330 Zinc, 0-0927 Antimony, 0-0507 Silver, 0-0557 Copper, 0-0949 Platinum, 0-0355 Glass, 0.1770 0-0350 0-1015 0-0549 0-0611 01013 0-0355 0-1900 CAL 265 CAL The capacity of iron was determined at the four following intervals : From to lOOo, the capacity is 0-10.08 to 200 0-1150 to 300 0-1218 to 350 0-1255 If we estimate the temperatures, as some philosophers have proposed, by the ratios of the quantities of heat which the same body gives out in cooling to a determinate tempera- ture, in order that this calculation be exact it would be necessary that the body in cooling, for example, from 300 to 0, should give out three times as much heat as in cooling from 100 to 0. But it will give out more than three times as much, because the capacities are increasing. We should therefore find too high a temperature. We exhibit in the following table the temperatures that would be deduced by employing the different metals contained in the preceding table. We must suppose that they have been all placed in the same liquid bath at 300, measured by an air thermo- meter. - Iron, Mercury, Zinc, Antimony, Silver, Copper, Platinum, Glass, 332-2 318-2 328-5 324-8 329-3 320-0 317-9 322-1 Experiments have been instituted, and the- orems constructed, for determining ths absolute quantity of heat in bodies, and the point of the total privation of that power, or of absolute cold, on the thermometric scale. The general principle on which most of the inquirers have proceeded is due to the ingenuity of Dr. Irvine. Supposing, for example, the capacity of iea to be to that of water as 8 to 10, at the temperature of 32, we know that in order to liquefy a cer- tain weight of ice, as much heat is required as would heat ths same weight of water to 140 Fahr. Hence, 140 represent two-tenths or one-finh of the whole heat of fluid water; and therefore the whole heat will be 5 X 140 = 700 below 32. It is needless to present any algebraic equations on a principle which is probably erroneous, and which has certainly produced in experiment most discordant re- sults. Mr. Dalton has given a general view of them in his section on the zero of tempera- ture. If we estimate the capacity of ice to that of water as 9 to 10, then the zero wiD come out . . .v; . 1400 Gadolin, from the heat evolved in~"| 2936 mixing sulphuric acid and water in | 1710 different proportions, and comparing ! 1510 the capacity of the compound with f 2637 those of its components, deduced the | 3230 opposite numbers, J 1740 Mr. Dalton from sulphuric acid and wa- ter, 6400 Ditto ditto ditto 4150 Ditto ditto ditto 6000 He thinks these to be no nearer approxima- tions to the truth than Gadoliu's. From the heat evolved in slaking" 1 ! lime, compared to the specific heats of I the compound, and its constituents, >- 4260 lime and water, Mr. Dalton gives as j the zero, "': T J From nitric acid and lime, Mr. Dalton finds .... 11000 From the combustion of hydrogen, 5400 From Lavoisier and Laplace's experiments on slaked lime, 3428 From their experiments on sulphuric acid and water, ' * ! -, 7262 Ditto ditto ditto 2598 Ditto from nitric acid and lime, + 23837 Dr. Irvine placed it below 30, = 900 Dr. Crawford ditto ditto, = 1500 The above result of Lavoisier and Laplace on nitric acid and lime, shows the theorem in a very absurd point of view, for it places the zero of cold above melting platina. MM. Cle- ment and Desormes have been lately searching after the absolute zero, and are convinced that it is at 266.66 below the zero of the centigrade scale, or 448 Fahr. This is a more con- ceivable result. But MM. Dulong and Petit have been led by their investigation to fix the absolute zero at infinity. " This opinion," say they, " rejected by a great many philo- sophers because it leads to the notion that the quantity of heat in bodies is infinite, supposing their capacity constant, becomes probable, now that we know that the specific heats diminish as the temperatures sink. In fact, the law of this diminution may be such, that the integral low, value." They further infer, that the quantity of heat developed at the instant of the combination of bodies has no relation to the capacity of the elements ; and that in the greatest number of cases, this loss of heat is not followed by any diminution in the capacity of the compounds formed. This consequence of their researches, if correct, is fatal to the theorem of Irvine, and to all the inferences that have beei\ drawn from it. 3. Of the general habitudes of heat, with the different for ms of matter. The effects of heat are either transient and physical, or permanent and chemical, inducing a durable change in the constitution of bodies. The second mode of operation we shall treat of under COMBUSTION. The first falls to be discussed here ; and divides itself naturally into the two heads, of changes in the volume of bodies while they retain their form, and changes in the state of bodies. 1st, The successive increments of volume which bodies receive with successive incre- of heat, taken to a temperature in finitely ma}' notwithstanding have a finite val CAL 266 CAL ments of temperature, have been the subjects of innumerable researches. The expansion of fluids is so much greater than that of solids by the same elevation of their temperature, that it becomes an easy task to ascertain within certain limits the augmentation of vo- lume which liquids and gases suffer through a moderate thermometric range. We have only to enclose them in a glass vessel of a proper form, and expose it to heat. But to determine their expansions with final accuracy, and free the results from the errors arising from the unequable expansion of the recipient, is a problem of no small difficulty. It seems, however, after many vain attempts by pre- ceding experimenters, to have been finally solved by MM. Dulong and Petit. The ex- pansion of solids had been previously mea- sured with considerable accuracy by several philosophers, particularly by Smeaton, Roy, Ramsden, and Troughton, in this country, and Lavoisier and Laplace in France. The method devised by General Roy, and exe- cuted by him in conjunction with Ramsden, deserves the preference. The metallic or other rod, the subject of experiment, was placed horizontally in a rectangular trough of water, which could be conveniently heated. At any aliquot distance on the rod, two micrometer microscopes were attached at right angles to it, so that each being adjusted at first to two im- moveable points, exterior to the heating ap- paratus, when the rod was elongated by heat, the displacement of the microscopes could be determined to a very minute quantity, to the twenty or thirty thousandth of an inch, by the micrometrical mechanism. The apparatus of Lavoisier and Laplace was on Smeaton's plan, a series of levers ; but differed in this respect, that the last lever gave a vertical motion to a telescope of six feet focal length, whose quantity of displacement was determined by a scale in its field of view from 100 to 200 yards distant. This addition of a micrometrical telescope was ingenious ; but the whole mechanism is liable to many objections, from which that of Ramsden was free. Still when managed by such hands and heads as those of Lavoisier and Laplace, we must re- gard its results with veneration. MM. Dulong and Petit have measured the dilatations of some solids as well as mercury, on plans which merit equal praise for their originality and phi- losophical precision. They commenced with mercury. Their method with it is founded on this incontestable law of hydrostatics, that when two columns of a liquid communicate by means of a lateral tube, the vertical heights of these two columns are precisely the inverse of their densities. In the axis of two upright copper cylinders, vertical tubes of glass were fixed, joined together at bottom by a horizontal glass tube resting on a levelled iron bar. One of the cylinders was charged with ice, the other with oil, to be warmed at pleasure by a subjacent stove. The rectangular inverted glass syphon was filled nearly to the top with mer- cury, and the height at which the liquid stood in each leg was determined with nicety by a telescopic micrometer, revolving in a horizontal plane on a vertical rod. The telescope had a spirit level attached to it, and could be moved up or down a very minute quantity by a fine screw. The temperature of the oil, the me- dium of heat, was measured by both an air and a mercurial thermometer, whose bulbs oc- cupied nearly the whole vertical extent of the cylinder. The elongation of the heated co- lumn of mercury could be rigorously known by directing the eye through the micrometer, first to its surface, and next to that in the ice- cold leg. Having by a series of careful trials ascertained the expansions of mercury through different thermometric ranges, they then de- termined the expansion of glass from the ap- parent expansions of mercury within it. They filled a thermometer with well boiled mercury, and plunging it into ice, waited till the liquid became stationary, and then cut across the stem at the point where the mercury stood. After weighing it exactly, they immersed it for some time in boiling water. On with- drawing, wiping, and weighing it, they learned the quantity of mercury expelled, which being compared with the whole weight of the mer- cury in it at the temperature of melting ice, gave the dilatation of volume. This is pre- cisely the plan employed long ago by Mr. Crighton, as well as myself, and which gave the quantity l-63d, employed in my paper, for the apparent dilatation of mercury in glass. Their next project was to measure the dila- tation of other solids; and this they accom- plished with much ingenuity, by enclosing a cylinder of the solid, iron for example, in a glass tube, which was filled up with mercury, after its point had been drawn out to a capil- lary point The mercury having been pre- viously boiled in it, to expel all air and mois- ture, the tube was exposed to different tem- peratures. By determining the weight of the mercury which was driven out, it was easy to deduce the dilatation of the iron ; for the vo- lume driven out obviously represents the sum of the dilatations of the mercury and the metal, diminished by the dilatation of the glass. To make the calculation, it is necessary to know the volumes of these three bodies at the tem- perature of freezing water; but that of the iron is obtained by dividing its weight by its density at 32. We deduce in the same man- ner the volume of the glass from the quantity of mercury which fills it at that temperature. That of the mercury is obviously the difference of the first two. The process just pointed out may be applied likewise to other metals, taking the precaution merely to oxidize their surface in order to hinder amalgamation. In the years 1812 and 1813 I made many experiments with a micrometrical apparatus of CAL 267 CAL a peculiar construction, for measuring the dila- tation of solids. I was particularly perplexed with the rods of zinc, which after innumerable trials I finally found to elongate permanently by being alternately heated and cooled. It would seem that the plates composing this metal, in sliding over each other by the ex- pansive force of heat, present such an adhesive friction as to prevent their entire retraction. It would be desirable to know the limit of this effect, and to see what other metals are subject to the same change. I hope to be able erelong to finish these pyrometrical researches. I shall now present a copious table of dila- tations, newly compiled from the best expe- riments. TABLE I. Linear Dilatation of Solids ly Heat. Dimensions which a bar takes at 212, whose length at 32 is 1.000000. Dilatation in Vulgar Fractions. Glass tube, Smeaton . . . 1.00083333 do. Roy, . -> . - 1-00077615 do. Deluc'smean, - - 1-00082800 rrnr do. do. Dulong and Petit, - 1-00086130 Lavoisier and Laplace, 1-00081166 TT&1S Plate glass, do. do. 1.000890890 -1*42 do. crown glass, do. do. 1-00087572 TTT* do. do. do. do. 1-00089760 'lO^g do. do. do. do. 1-00091751 do. rod, Roy, . *' V' 1-00080787 Deal, Platina, Borda, . . 1-00085655 do. Dulong and Petit, 1 -00088420 TrVr do. Troughton, . 1-00099180 do. and glass, Berthoud, . 1-00110000 Palladium, Wollaston, V 1-00100000 Antimony, Smeaton, . 1.00108300 Cast iron prism, Roy, . . 1.00110940 Cast iron, Lavoisier, by Dr. Young, 1-00111111 Steel, Troughton, V- 1.00118990 Steel rod, Roy, . 1-00114470 Blustered steel, Phil. Trans. 1795. 428 1-00112500 do. Smeaton, . 1-00115000 Steel not tempered, Lavoisier and Laplace, -00107875 5%r do. do. do. do. do. .00107956 Uafe do. tempered yellow, do. do. -00136900 do. do. do. do. do. -00138600 do. do. do. at a higher heat, do. do. -00123956 1T5T Steel, Troughton, . . -00118980 Hard steel, Smeaton, . . . -00122500 Annealed steel, Muschenbroek, . . -00122000 Tempered steel, do. . . -00137000 Iron, Borda, . - "* . -00115600 do. Smeaton, . - -00125800 Soft iron, forged, Lavoisier and Laplace, -00122045 Round iron, wire-drawn, do. do. -00123504 Iron wire, Troughton, . . -00144010 Iron, Dulong and Petit, . -00118203 845 Bismuth, Smeaton, . . -00139200 Annealed gold, Muschenbroek, . -00146000 Gold, Ellicot, by comparison, -00150000 do. procured by parting, do. Paris standard, unannealed, Lavoisier and Laplace, -00146606 do. do. -00155155 rf* wfe do. do. annealed, do. do. -00151361 Copper, Muschenbroek, . . -0019100 Lavoisier and Laplace, -00172244 S8 r do. do. do. -00171222 Tsf5 do. Troughton, . . 1-00191880 do. Dulong and Petit, . 1.00171821 582 Brass, Borda, . . 1-00178300 do. Lavoisier and Laplace, 1-00186671 do. do. do. 1-00188971 Brass scale, supposed from Hamburg, Roy, - . . 1-00185640 CAL 268 CAL Cast brass, English plate-brass, in rod, do. do. in a trough form, Brass, Brass wire, Copper 8, tin 1, Silver, do. do. do. of cupel, do. Paris standard, Silver, Brass 16, tin 1, Speculum metal, Spelter solder ; brass 2, zinc 1 , Malacca tin, Tin from Falmouth, Fine pewter, Grain tin, Tin, Soft solder ; lead 2, tin 1, Zinc 8, tin 1, a little hammered, Lead, do. Zinc, Zinc, hammered out inch per foot, Glass, from 32, to 212, do. from 212, to 392, do. from 392<>, to 572, The last two measurements by an air thermometer. 12, whose length at 32S is 1.000000. Di'at in V; Smeaton, . 1-00187500 Frac- Roy, . 1.00189280 do. 1-00189490 Troughton, 1-00191880 Smeaton, 1-00193000 Muschenbroek, 1-00216000 Smeaton, 1-00181700 Herbert, 1-00189000 Ellicot, by comparison, 1-0021000 Muschenbroek, 1-00212000 Lavoisier and Laplace, do. do. 1-00190974 1-00190868 Troughton, 1-0020826 524 Smeaton, 1-00190800 do. . . 1.00193300 do. . . 1-00205800 Lavoisier and Laplace. 1-00193765 r^r do. do. 1-00217298 3*2 Smeaton, 1-00228300 do. ... 1-00248300 Muschenbroek, 1-00284000 Smeaton, 1-00250800 do. 1-00269200 Lavoisier and Laplace, Smeaton, 1.00284836 1-00286700 sir do. 1.00294200 do. 1-00301100 D along and Petit, 1.00086130 nVr do. do. 1-00091827 ToW do. do. 1-000101114 -strr To obtain the expansion in volume, mul- tiply the above decimal quantities by three, or divide the denominators of the vulgar fractions by three ; the quotient in either case is the di- latation sought We see that a condensed metal, one whose particles have been forcibly approximated by the wire-drawing process, expands more, as might be expected, than metals in a looser state of aggregation. The result for pewter, I con- ceive, must be inaccurate. Lead ought to communicate to tin, surely, a greater expan- sive property. Borda's measure of platina is important. It was observed with the tules which served for ineasuring the base of the tri- gonometrical survey in France. The observa- tions in the table on tempered steel, are, I be- lieve, by that eminent artist, Fortin, though they are included in the table which M. Biot published, under the title of Lavoisier and La- place. The amount of the dilatation of metals be- comes very useful to determine, in certain cases, the change of dimension to which astronomical instruments are liable. Thus, in measuring a base for the grand operation of the meridian of France, Borda sought to elude the uncertainties arising from expansion of the measuring rods, by combining metallic bars, so that they indicated, of themselves, their va- nations of temperature and of length. A rule of platina, twelve feet long, was attached by one of its extremities to a rule of copper somewhat shorter, which rested freely on its surface, when placed in a horizontal position. Towards the loose end of the copper rule, there was traced on the platina rule very exact linear divisions, the parts of which were mil- lionths of the total length of this rule. The end of the copper rule carried a vernier, whose coincidences with the platina graduations were observed with a microscope. Now, the dila- tations of the platina and copper being unequal for equal changes of temperature, we may conceive that the vernier of the copper rule would incessantly correspond to variable di- visions, according as the temperatures varied. Borda made use of these changes to know at every instant the common temperature of these two bars, and the ratio of the absolute dilata- tions of then: two metals. The value of the vernier divisions had been previously ascer- tained, by plunging the compound bar into water of different temperatures, contained in an oblong wooden trough. It was therefore sufficient to read the indications of this me- tallic thermometer, in order to learn the true temperature of the bars in the atmosphere ; and, of course, the compensation to be made in the meter rods or chains, to bring them to the true length at the standard temperature. An exact acquaintance with the dilatation CAL 269 CAL of metals, is also necessary for regulating the length of the pendulum in astronomical clocks. When the ball or bob of a seconds pendulum is let down -j^ of an inch, the clock will go ten seconds slower in 24 hours ; and therefore Vo * of an inch will make it lose one second per day. Now, as the effective length of the seconds pendulum is 39-13929 inches, we know from the previous table of expansion, that a change of 30 degrees of temperature by Fahrenheit's scale, will alter its length about SoW P 31 "^ which is equivalent to nearly 0-0078, or ^ of an inch, corresponding to about eight seconds of error in the day. The first, the most simple, and most perfect in- vention for obviating these variations, is due to Graham. The bob of his compensation pendulum consisted of a glass cylinder, about six inches long, holding ten or twelve pounds of mercury. In proportion as the iron or steel rod to which this was suspended, dilated by heat, the mercury also expanded, and raised thereby the centre of oscillation, just as much as the lengthening of the rod had depressed it M. Biot, with his usual accuracy, has shown, that if the suspending rod were of glass, the length of the cylinder of mercury would require to be 1-1 Oth the total length of the pendulum, namely, about four inches; but the expansion of iron being greater in the ratio, pretty nearly of three to two, we have hence the length of the cylinder in the latter case, equal to about six inches. The late very ingenious Mr. Gavin Lowe prescribed, along with a steel rod, a glass cylinder two inches diameter inside, containing 6-*$ vertical inches of mercury, weighing ten pounds. From ac- curate calculation he found, that if such a pendulum should go perfectly true when the thermometer is at 30, but that at 90 it should go one second slower in 24 hours, it would be remedied by pouring in ten ounces more quicksilver ; or, by taking out that quantity, if it went one second faster in 24 hours, when at 90 than at 30 Fahr. ; and for l-10th of a second of deviation in 24 hours, the compensation is the addition or abstraction of one ounce of mercury. See a useful paper on this subject, by Mr. Firminger, in the Philosophical Magazine for August 1819. The balance wheel of a watch varies, in the time of its oscillations, by its expansions and contractions with variations of temperature. The invention of Arnold furnished awheel or interrupted ring, composed of concentric laminae of two metals, which, obviating the above defect by their difference of dilatation, has, under the name of compensation balance, incalculably improved the accuracy of marine chronometers. We shall describe under THER- MOMETER, an elegant instrument constructed on similar principles, by the celebrated M. Breguet. See other applications, infra. TABLE II. Dilatation oftJie volume of LIQUIDS by leing heated from 32<> to 212". Mercury, Dalton, do. Lord Charles Cavendish, do. Deluc, . ... do. General Roy, do. Shuckburgh, do. Lavoisier and Laplace, do. Haelestroem, do. Dulong and Petit, do. do. from 212, to 392 do. do. from 392, to 572 do. do. in glass, from 32, to 212, do. do. do. from 212, to 392, ' . do. do. do. from 392, to 572, * Water, Kirwan, from 39, its maximum density, Muriatic acid, (sp. gr. 1-137), Dalton, Nitric acid, (sp. gr. 1-40), do. Sul phuric acid, (sp. gr. 1-85), do. ^. Alcohol, . ' : fc . do. . x* Water, . .. . do. Water saturated with common salt, do. .* Sulphuric ether, ; .. . do. , Fixed oils, . . . do. - . . Oil of turpentine, . . do. ,.- . The quantities given by Mr. Dalton are probably too great, as is certainly the case with mercury ; his experiments being perhaps modified by his hypo- thetical notions. Water saturated with common salt, Robison, 0-020000 A 0-018870 $ 0-018000 4 0.017000 T& 0-01851 4 0-01810 TTS.TS 0-0181800 3 0-0180180 TJ-7TT 0-0184331 Trf** 0-0188700 s 0-015432 ^F 0-015680 TTS-Ta 0-0158280 S3*TJT 0-04332 23 l .-<57 0-0600 iV 0-1100 * 0-0600 iV 0-1100 i 0-0460 A 0-0500 A 0-0700 T 1 * 0-0800 *** 0-0700 ft 0-05198 & CAL 270 CAL Dr. Young, in his valuable Catalogue Rai- tonnec. Natural Philosophy, vol. ii. p. 391, gives the following table of the expansions of water, constructed from a collation of experi- ments by Gilpin, Kirwan, and Achard. He says, that the degrees of Fahrenheit's ther- mometer, reckoning either way from 39 being called/, the expansion of water is nearly ex- pressed by 22/ 2 (1 002/) in 10 millionths ; and the diminution of the spec, gravity by 0000022/* -00000000472/3. This equa- tion, as well as the table, are very important for the reduction of specific gravities of bodies, taken by weighing them in water. Sp. grav. Dimin. of sp. gr. Expansion. 30o 0-99980 0-00020 32 0-99988 0-00012 34 0-99994 0-00006 39 1-00000 0-00000 44 0-99994 0-00000 48 0-99982 0-00018 49 0-99978 0-00022 54 0-9995 1 0-00049 59 0-99914 0-00086 60 0-99906 0-00094 Sp. grav. Dimin. sp. gr. Expansion. . 64 0-99867 0-00133 69 0-99812 0-00188 74 0-99749 0-00251 (77) 0-99701 Achard 0-00299 79 0-99680 Gilpin 0-00320 0-00321 (82) 0-99612 Kirwan 0-00388 0-00389 90 0-99511 Gilpin 0-00489 0-00491 100 0-99313 0-00687 0-00692 102 0-99246 Kirwan 0-00754 0-00760 122 0-98757 0-01243 0-01258 0-98872 Deluc 0-01128 142 0-98199 K. 0-01801 0-01833 162 0-97583 0-02417 0-02481 167 0-97480 Deluc 0-02520 182 0-96900 K. 0-03100 0-03198 202 0-96145 003855 0-04005 212 0-95848 0-04152 0-04333 Deluc introduced into a series of ther- mometer glasses the following liquids, and noted their comparative indications by expan- sion at different degrees of heat, measured on Reaumur's thermometer, of which 80 is the boiling point of water, and the melting point of ice. TABLE of Thernwmetric Indications ly DELUC. Mercury. Olive Oil. Es. Oil of Chamomile. Oil of Thyme- Alcohol. Brine. Water. R. Cent. Fahr. 80 100 212 80 80 80 80 80 80 75 93| 2004 74.6 74.7 74.3 73.8 74.1 71 70 87.5 189x 69.4 69.5 68.8 67-8 68.4 62 65 81. 178J 64.4 64.3 63.5 61.9 62.6 53.5 60 75. 167 59.3 59.1 58.3 56.2 57.1 45.8 55 68f 155| 54.2 53.9 53.3 50.7 51.7 38.5 50 62J 14 4 49.2 48.8 48.3 45.3 46.6 32. 45 56} 1 33 | 44.0 43.6 43.4 40.2 41.2 26.1 40 50 122 39.2 38.6 38.4 35.1 36.3 20.5 35 43| 1104 34.2 33.6 33.5 30.3 31.3 15.9 30 99 29.3 28.7 28.6 25.6 26.5 11.2 25 314; ggi 24.3 23.8 23.8 21.0 21.9 7-3 20 25 77* 19.3 18.9 19.0 16.5 17.3 4.1 15 184 14.4 14.1 14.2 12.2 12.8 1.6 10 T*S 54 9.5 9.3 9.4 7.9 8.4 0.2 5 i 43! 4.7 4.6 4.7 3.9 4.2 0.4 32 4 0.0 0.0 0.0 0.0 0.0 0.0 5 64 -3.9 4.1 10 12| 2 9i -7-7 8.1 As I consider these results of Deluc valu- able, hi so far as they enable us to compare directly the expansions in glass of these dif- ferent thermometric liquids, I have added the two columns marked Cent, and Fahr. to give at once the reductions to the centigrade and Fahrenheit graduation. The alcohol was of such strength that its flame kindled gun- powder, and it was found that the results were not much changed by a small difference in the strength of the spirit. The brine was water saturated with common salt. M. Biot, in the first volume of his elaborate Traite de Physique, has investigated several empyrical formulas, to represent the laws of dilatation of the different fluids. They are too complex for a work of this nature. He shows that for all liquids whose dilatations have been hitherto observed, the general march of this dilatation may be represented at every temperature by an expression of this form, *t = at + Zrt + c/3, in which t denotes the temperature in degrees of the mercurial ther-, CAL 271 CAL mometer; a b e constant coefficients, which depend on the nature of the liquid ; and t the true dilatation for the volume 1.0 from the temperature of melting ice. We shall content ourselves with giving one example, from which we may judge of the great geometrical re- sources of this philosopher. For olive oil the formula becomes D T = 0.95067 T + 0.00075 T* 0.000001667 T\ The following table gives its results com- pared with experiment. Of the mercurial. Calculated. Observed. 80 80 80 70 69.64 69.41 60 59.37 59.3 50- 49.2 49.2 40 39.12 39.2 30 29.15 29.3 20 19.30 19.3 10 9.58 9.5 0.0 0. M. Gay Lussac has lately endeavoured to discover some law which should correspond with the rate of dilatation of different liquids by heat. For this purpose, instead of com- paring the dilatations of different liquids, above or below a temperature uniform for all, he set out from a point variable with regard to temperature, but uniform as to the cohesion of the particles of the bodies ; namely, from the point at which each liquid boils under a given pressure. Among those which he ex- amined, he found two which dilate equally from that point, viz. alcohol and sulphuret of carbon, of which the former boils at 173.14, the latter at 1 15.9 Fahr. The other liquids did not present, in this respect, the same re- semblance. Another analogy of the above two liquids is, that the same volume of each gives, at its boiling point, under the same atmospheric pressure, the same volume of vapour ; or, in other words, that the densities of their vapours are to each other as those of the liquids at their respective boiling temperatures. The following table shows the results of this dis- tinguished chemist. TABLE of tlie Contractions of 1000 parts in volume, by cooling. Water. Alcohol. Sulphuret of Carb. Ether. Contract by expt. Ditto calculated. Contract by expt. Ditto calculated. Contract by expt. Ditto calculated. Contract by expt Ditto calculated. Boiling, 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 3.34 3.35 5.55 5.56 6.14 6.07 8.15 8.16 10 6.61 6.65 11.43 11.24 12.01 12.08 16.17 16.01 15 10.50 9.89 17-51 17.00 17-98 17.99 24.16 23.60 20 13.15 13.03 24.34 23.41 23.80 23.80 31.83 30.92 25 16.06 16.06 29.15 28.60 29.65 29.50 39.14 38.08 30 18.85 18.95 34.74 34.37 35.06 35.05 46.42 45.04 35 21.52 21.67 40.28 40.05 40.48 40.43 52.06 51.86 40 24.10 24.20 45.68 45.66 45.77 45.67 58.77 58.77 45 26.50 26.52 50.85 51.11 51.08 50.70 65.48 65.20 50 28.56 28.61 56.02 56.37 56.28 55.52 72.01 71.79 55 30.60 30.43 61.01 61.43 61.14 60.12 78.38 78.36 60 32.42 31.96 65.96 66.23 66.21 64.48 65 34.02 33.19 10.74 70.75 -70 35.47 34.09 75.48 74.93 -75 36.70 34.63 80.11 78.75 Their respective boiling points are : Water, - 100 Cent = 212 F. Alcohol, - 78.41 173 Sulphuret of carb. 46.60 126 Sulphuric ether, 35.66 96 The experiments were made in thermometer vessels hermetically sealed. Alcohol, at 78.41 cent, produces 488.3 its vol. of vapour. Sulphuret of carbon, at 46.60 cent, pro- duces 491.1 its vol. of vapour. Ether, at 35.66 cent, produces 285.9 its vol. of vapour. Water, at 100.00 cent, produces 1633.1 its vol. of vapour. In solid metals, the expansion seems to be greater, the less their tenacity and density, though to this general position we have striking exceptions in antimony and bismuth, provided they were accurately measured by Smeaton's apparatus, of which, however, I have reason to doubt. The least flexure in the expanding rods, will evidently make the expansions come out too small. If metallic dilatability vary with some unknown function of density and tenacity, as is probable a priori, we would expect their rate of expansion to increase with the temperature. This view coincides with the following results of MM. Dulong and Petit CAL 272 CAL Temperatures by - Expansions in dilatation of air. bulk of Iron. Cop. Plat. to 100 cent, give ^ ^ ^ to 300, mean quantity, ^ T ~^ r -^ Tripling these denominators, we have the linear expansions, fractionally expressed thus : to 100 cent. 0" to 300 mean, Iron. Cop. Plat. tt& TS&S TTST FST T3T TcnSS To multiply inductive generalizations, that is, to group together facts which have some important qualities common to them all, is the main scope and business of philosophy. But to imagine phenomena, or to twist real pheno- mena into the shape suited to a preconceived constitution of things, was the vice of the Pe- ripatetic schools, which Bacon so admirably exposed ; of which in our times and studies, according to MM. Dulong and Petit, many of our speculations on the laws of heat afford a striking example. Mr. Dalton has the merit of having first proved that the expansions of all aeriform bodies, when insulated from liquids, are uni- form by the same increase of temperature ; a fact of great importance to practical chemistry, which was fully verified by the independent and equally original researches of M. Gay Lussac on the subject, with a more refined and exact apparatus. Both of these philosophers demonstrated, that 100 in volume at 32 Fahr. or cent, become 1.375 at 212 Fahr. or 100 cent. Hence the increment of bulk for each degree F. is Qjf^s = 0.002083 = ^ ; and for the centigrade scale it is J: = 0.00375 2&B"*' Thus 48 P arts in volume at 32 F. become at 60 F. 480 + 28 = 508 ; and at 120 F. they become 480 + 88 = 568. Hence the volumes of any dry gas at these two temperatures will be to each other in the ratio of f . For example, 25 cubic inches at 120 F. will become 25 X f 22 - 36 at CO . Or calling the volume at 32 unity 1.00000, it will become 1.05833 at 60, and 1.18333 at 120. But 25 multiplied by the fraction i.-^|^|| = 22.36 as before. 1 have constructed a new table, to save much of this arithmetical operation, which will be found in the APPENDIX. Vapours, when heated out of contact of their respective liquids, obey the same law as gases; a discovery due to M. Gay Lussac. We shall now treat of the anomaly present- ed by water in its dilatations by change of tem- perature, and then conclude this part of the subject with some practical applications of the preceding facts. The Florentine academicians, and after them Dr. Croune, observed, that on cooling in ice and salt the bulb of a thermometric glass vessel filled with water, the liquid progressively sunk in the stem, till a certain point, after which the further progress of refrigeration was accompa- nied by an ascent of the liquid, indicating ex- pansion of the water. This curious phenome- non was first accurately studied by M. Deluc, who placed the apparent term of greatest den- sity at 40 Fahr., and considered the expansion of water from that point, to vary with equal amount, by an equal change of temperature, whether of increase or decrease. Having omitted to make the requisite correction for the effect of the expansion of the glass in which the water was contained, it was found after- wards by Sir Charles Blagden and Mr. Gilpin, who introduced this correction, that the real term of greatest density was 39 F. The following Talk gives their experimental results. Sp. gravity. Bulk of water. Temperature. Bulk of water. Sp. gravity. 1.00000 39 1.00000 .00000 .00000 38 40 .00000 1.00000 0.99999 .00001 37 41 .00001 0.99999 '.99998 .00002 36 42 .00002 0.99998 .99996 .U0004 35 43 .00004 0.99996 0.99994 .OOOC6 34 44 1.00006 0.99994 0.99991 1.00008 33 45 1.00009 0.99991 0.99988 1.00012 32 46 1.00012 0.99988 By weighing a cylinder of copper and of the co-Triplication introduced into the ques- glass in water at different temperatures, the tion by the expansion of solids, is very philo- maximum density comes out 40 F. Finally, sophically removed. He shows that water Dr. Hope in 1804 published a set of experi- exposed in tall cylindrical vessels, to a freez- ments in the Edin. Philos. Trans, in which ing atmosphere, precipitates to the bottom its CAL 273 CAL colder particles, till the temperature of the mass sinks to 39.5 F., after which the colder particles are found at the surface. He varied the form of the experiment by applying a zone of ice round the top, middle, and bottom of the cylinders ; and in each case, delicate ther- mometers placed at the surface and bottom of the water, indicated that the temperature 39.5, coincided with the maximum density. We may therefore regard the point of 40, adopted by the French in settling their stan- dard of weights and measures, as sufficiently exact. The force with which solids and liquids expand or contract by heat and cold, is so prodigiously great as to overcome the strongest obstacles. Some years ago it was observed at the Conservatoire dcs arts et metiers at Paris, that the two side walls of a gallery were re- ceding from each other, being pressed out- wards by the weight of the roof and floors. Several holes were made in each of the walls, opposite to one another, and at equal dis- tances, through which strong iron bars were introduced so as to traverse the chamber. Their ends outside of the wall were furnished with thick iron discs, firmly screwed on. These were sufficient to retain the walls in their actual position. But to bring them nearer together would have surpassed every effort of human strength. All the alternate bars of the series were now heated at once by lamps, in consequence of which they were elongated. The exterior discs being thus freed from contact of the walls, permitted them to be advanced farther, on the screwed ends of the bars. On removing the lamps, the bars cooled, contracted, and drew in the opposite walls. The other bars became in consequence loose at their extremities, and permitted their end plates to be further screwed on. The first series of bars being again heated, the above process was repeated in each of its steps. By a succession of these experi- ments they restored the walls to the perpendi- cular position ; and could easily have reversed their curvature inwards, if they had chosen. The gallery still exists with its bars, to attest the ingenuity of its preserver M. Molard. 2d, Of the change of state produced in lodies ly caloric, independent of change of composition. The three forms of matter, the solid, liquid, and gaseous, seem immediately referable to the power of heat, modifying, balancing, or subduing cohesive attraction. In the article Blowpipe we have shown, that every solid may be liquefied, and many of them, as well as all liquids, may be vaporized at a certain elevation of temperature. And conversely, almost every known liquid may be solidified by the reduction of its temperature. If we have not hitherto been able to convert the air and all other elastic fluids into liquids or solids, it is probably owing to the limited power we possess over thermometric depres- sion. But we know, that many gases may be liquefied by mechanical approximation of their elastic particles, as also by cold, which must convince us that their gaseity is inti- mately dependent on the operation of that re- pulsive power. Sulphuric ether, always a liquid in our cli- mate, if exposed to the rigours of a Siberian winter, would become a solid, and, transported to the torrid zone, would form a permanent gas. The same transitions are familiar to us with regard to water, only its vaporizing point, being much higher, leads us at first to suppose steam an unnatural condition. But by general- izing our ideas, we learn that there is really no state of bodies which can be called more natural than another. Solidity, liquidity, the state of vapours and gases, are only accidents connected with a particular level of tempera- ture. If we pass the easily condensed vapour of nitric acid through a red-hot glass tube, we shall convert it into gases which are inconden- sable by any degree of cold which we can com- mand. The particles which formed the liquid can no longer join together to reproduce it, be- cause their distances are changed, and with these have also changed the reciprocal attrac- tions which united them. Were our planet removed much further from the sun, liquids and gases would solidify ; were it brought nearer that luminary, the bodies which appear to us, the most solid, would be reduced into thin invisible air. We see then that the principle of heat, whatever it may be, whether matter or quality, separates the parti- cles of bodies when its energy augments, and suffers them to approach when its power is en- feebled. By extending this view, it has been drawn into a general conclusion, that this prin- ciple was itself the force which maintains the particles of bodies in equilibria against the effort of their reciprocal attraction, which tends continually to bring them together. But al- though this conclusion be extremely probable, we must remember that it is hypothetical, and goes further than the facts. We see that the force which balances attraction in bodies may be favoured or opposed by the principle of heat, but this does not necessarily prove that these forces are of the same nature. The instant of equilibrium which separates the solid from the liquid state, deserves consi- deration. Whatever may be the cause and law of the attractions which the particles exercise on one another, the effect which results ought to be modified by their forms. When all the other qualities are equal, a particle which may be cylindrical, for example, will not exercise the same attraction as a sphere, on a point placed at an equal distance from its centre of gravity. Thus, in the law of celestial gravi- tation, the attraction of an ellipsoid on an ex- terior point will be stronger in the direction of its smaller than in that of its larger axis, at the same distance from its surface. Now, T CAL 274 CAL whatever be the law of attractions which holds together the particles of bodies, similar differ, ences must exist. These particles must be attracted more strongly by certain sides than by others. Thence must result differences in the manner of their arrangement, when they are sufficiently approximated for their attrac- tions to overcome the repulsive power. This explains td us in a very probable manner, the regular crystallization which most solid bodies assume, when they concrete undisturbed. We may easily conceive how the different substance of the particles, as well as their different forms, may produce in crystals all the varieties which we observe. The system of the world presents magnifi- cent effects of this attraction dependent on figure. Such are the phenomena of nutation and the precession of the equinoxes, produced by the attractions of the sun and moon on the flattened spheroid of the earth. These sublime phenomena would not have existed had the earth been a sphere : they are connected with its oblateness and rotation, in a manner which may be mathematically deduced, and subjected to calculation. But the investigation shows, that this part of the attraction dependent on figure, decreases more rapidly than the principal force. The latter diminishes as the square of the distance ; the part dependent on figure diminishes as the cube of the distance. Thus also, in the attrac- tions which hold the parts of bodies united, we ought to expect an analogous difference to oc- cur. Hence the force of crystallization may be subdued, before the principal attractive force is overcome. When the particles are brought to this distance, they will be indifferent to all the positions which they can assume round their centre of gravity ; this will constitute the liquid condition. Suppose now that the temperature falling, the particles approach slowly to each other, and tend to solidify anew ; then the forces dependent on their figure will come again into play, and in proportion as they in- crease, the particles solicited by these forces will take movements round their centres of gravity. They will turn towards each other their faces of greatest attraction, to arrive finally at the positions which their crystalliza- tion demands. Now, according to the figure of the particles, we may conceive that these movements may react on their centre of gra- vity, and cause them to approach or recede gradually from each other, till they finally give to their assemblage the volume due to the solid state; a volume which in certain cases may be greater, and in others smaller, than that which they occupied as liquids. These mechanical considerations thus explain, in the most probable and satisfactory manner, the dilatations and contractions of an irregular kind, which certain liquids, such as water and mercury, experience on approaching the term of their congelation. Having given these ge- neral views, we may now content ourselves with stating the facts as much as possible in a tabular form. TABLE of the Concreting or Congealing Temperatiires of various Liquids by FAH- RENHEIT'S Scale. Sulphuric ether, . ..,.*. 46 Liquid ammonia, . . 46 Nitric acid, sp. gr. 1.424 45.5 Sulphuric acid, sp. gr. 1.6415 45 Mercury . . . . 39 Nitric acid, sp. gr. . 1.047 30.1 Sulphuric acid, . 1.8064 26 Nitric acid, , .. .. 1.3880 18.1 Do. Do. . 1.2583 17-7 Do. Do. . 1.3290 2.4 Brandy, _ ,.",.,' 7-0 Sulphuric acid, ^ .., 1.8376 + 1 Pure prussic acid, . . 4 to 5 Common salt, 25 + water 75 4 Do. 22.2 + do. 77-3 7-2 Sal ammoniac, 20 + do. 80 8 C. Salt, 20 -j- do. 80 9.5 Do. 16.1 4- do. 83.9 13.5 Oil of turpentine, . ,, , 14 Strong wines, . . ^ , 20 Rochelle salt, 50 -f water 50 21 C. Salt, 10 + do. 90 21.5 Oil of bergamot, ... 23 Blood, . .... . . 25 C. Salt, 6.25 + water 93.75 25.5 Eps. salts, 41.6 -f do. 58.4 25.5 Nitre, 12.5 + do. 87-5 26 C. Salt, 4,16 + do. 95.84 27.5 Copperas, 41.6 + do. 58.4 28 Vinegar . -. ^ . ..,,.,., , 28 Sul.of zinc, 53.3 + do. 46-7 28.6 Milk, ... 30 Water, ,;,-. ; . .,/ , ,,...."; 32 Olive oil, . r .,,. ^,. fJv 36 Sulphur and phosphorus, equal parts, 40 Sulphuric acid, sp. gr. 1.741 42 Do. Do. 1.780 46 Oil of anise, . . . 50 Concentrated acetic acid, ... 50 Tallow, Dr. Thomson, '. _...* v 92 Phosphorus, . . .'-. 108 Stearin from hog's lard, , ; , v , 109 Spermaceti, . ... jXj' . 112 Tallow, Nicholson, . . 127 Margaric acid, . . . 134 Potassium, , , " . '' . 136-4 Yellow wax, ... . 142 Do. Do. . . SrSp 149 White wax, ,.X . 155 Sodium, . 194 Sulphur, Dr. Thomson, ','.. 218 Do. Dr. Hope, . . 234 Tin, , .. . . 442 Bismuth, , . . 476 Lead, . . . 612 Zinc, by Sir H. Davy, .* 680 Do. Brogniart, , . V. 698 Antimony, . . ^ . 809 ? CAL 375 CAL See PYROMETER for higher heats. The solidifying temperature of the bodies above tallow, in the table, is usually called their freezing or congealing point; and of fcallow and the bodies below it, the fusing or melting point. Now, though these tempera- tures be stated, opposite to some of the articles, to fractions of a thermometric degree, it must be observed, that various circumstances modify the concreting point of the liquids, through several degrees ; but the liquefying points of the same bodies, when once solidified, are uni- form and fixed to the preceding tempera- tures. The preliminary remarks which we offered on the forces concerned in the transition from liquidity to solidity, will in some measure ex- plain these variations ; and we shall now illus- trate them by some instructive examples. If we fill a narrow-mouthed matrass with newly distilled water, and expose it very gra- dually to a temperature considerably below 32, the liquid water will be observed, by the thermometer left in it, to have sunk 1 or 1 1 degrees below its usual point of congelation. M. Gay Lussac, by covering the surface of the water with oil, has caused it to cool 21^ degrees Fahr. below the ordinary freezing tem- perature. Its volume at the same time ex- panded as much as if it had been heated 21^ degrees above 32. According to Sir Charles Blagden, to whom the first of these two ob- servations belongs, its dilatation may amount to l-7th of the total enlargement which it re- ceives by solidifying. Absolute repose of the liquid particles is not necessary to ensure the above phenomenon, for Sir Charles stirred water at 21 without causing it to freeze, but the least vibration of their mass, or the appli- cation of icy spiculae, by the atmosphere, or the hand, determines an instantaneous con- gelation. We may remark here, that the dilatation of the water increasing as it cools, but to a less extent than when it concretes, is a proof that its constituent particles, in obedience to the cooling process, turn their poles more and more towards the position of the maximum attraction, which constitutes their solid state. But this position may be determined instan- taneously by the ready formed aqueous solid, the particles of which presenting themselves to those of the liquid, by their sides of greatest attraction, will compel them to turn into similar positions. Then the particles of the liquid first reverted will act on their neighbours like the exterior crystal, and thus from point to point the movement will be propagated through the whole mass, till all be congealed. The vibra- tory movement acts by throwing the particles into positions favourable for their mutual at- traction. The very same phenomena occur with sa- line solutions. If a hot saturated solution of Glauber's salt be cooled to 50 under a film of oil, it will remain liquid, and will bear to be moved about in the hand without any change ; but if the phial containing it be placed on a vibrating table, crystallization will instantly take place. In a paper on saline crystallization which I published in the 9th number of the Journal of Science, I gave the following illustration of the above phenomena. " The effect of mechanical disturbance in de- termining crystaltoation, is illustrated by the symmetrical disposition of particles of dust and iron, by electricity and magnetism. Strew these upon a plane, and present magnetic and elec-- tric forces at a certain distance from it, no effect will be produced. Communicate to the plane a vibrating movement; the particles at the instant of being liberated from the friction of the surface, will arrange themselves according to the laws of their respective magnetic or electric attractions. The water of solution in counteracting solidity, not only removes the particles to distances beyond the sphere of mutual attraction, but probably also inverts their attracting poles." Perhaps the term avert would be more appropriate to liquidity, to denote an obliquity of direction in the at- tracting poles ; and revert might be applied to gaseity, when a repulsive state succeeds to the feebly attractive powers of liquid particles. The above table presents some interesting particulars relative to the acids. I have ex- pressed their strengths, by specific gravity, from my tables of the acids, instead of by the quantity of marble which 1000 grains of them could dissolve, in the original statement of Mr. Cavendish. Under the heads of ACID (Ni- TRIC) and EQUIVALENT, some observations will be found on these peculiarities with re- gard to congelation. We see that common salt possesses the greatest efficacy in coun- teracting the congelation of water ; and next to it, vsal ammoniac. Mr. Crighton, of Glas- gow, whose accuracy of observation is well known, has remarked, that when a mass of melted bismuth cools in the air, its tempera-- ture falls regularly to 468, from which term it however instantly springs up to 476, at which point it remains till the whole be con- solidated. Tin in like manner sinks and then rises 4 degrees ; while melted lead, in cooling, becomes stationary whenever it descends to 612. We shall presently find the probable cause of these curious phenomena. Water, all crystallizable solutions, and the metals, bismuth, and antimony, expand in volume, at the instant of solidification. The greatest obstacles cannot resist the exertion of this expansive force. Thus glass bottles, trunks of trees, iron and lead pipes, even mountain rocks, are burst by the dilatation of the water in their cavities, when it is converted into ice. In the same way our pavements are raised in winter. Major Williams, of Quebec, burst bombs, which were filled with water and plugged up, by exposirg them to a freezing T 2 CAL 276 CAL cold. The beneficial operation of this cause is exemplified in the comminution or loosen- ing the texture of dense clay soils, by the winter's frost, whereby the delicate fibres of plants can easily penetrate them. There is an important circumstance occurs in the preceding experiments on the sudden congelation of a body kept liquid below its usual congealing temperature, to which we must now advert. The mass, at the moment its crystallization commences, rises in tempe- rature to the term marked in the preceding table, whatever number of degrees it may have previously sunk below it. Suppose a globe of water suspended in an atmosphere at 21 F. ; the liquid will cool and remain stationary at this temperature, till vibration of the vessel, or contact of a spicula of ice, determines its concretion, when it instantly becomes 11 de- grees hotter than the surrounding medium. We owe the explanation of this fact, and its extension to many analogous chemical phe- nomena, to the sagacity of Dr. Black. His truly philosophical mind was particularly struck by the slowness with which a mass of ice liquefies when placed in a genial atmo- sphere. A lump of ice at 22 freely suspended in a room heated to 50, which will rise to 32 in 5 minutes, will take 14 times 5, or 70 mi- nutes, to melt into water, whose temperature will be only 32. Dr. Black suspended in an apartment two glass globules of the same size alongside of each other, one of which was filled with ice at 32, the other with water at 33. In half an hour the water had risen to 40 ; but it took 10| hours to liquefy the ice and heat the resulting water to 40. Both these experiments concur therefore in showing that the fusion of ice is accompanied with the expenditure of 140 degrees of calorific energy, which have no effect on the thermometer. For the first experiment tells us that 10 degrees of heat entered the ice in the space of 5 minutes, and yet 14 times that period passed in its liquefaction. The second experiment shows that 7 degrees of heat entered the globes in half an hour ; but 21 half hours were required for the fusion of the ice, and for heating of its water to 40. If from the product of 7 into 21 =147, we subtract the 7 degrees which the water was above 33, we have 140 as before. But the most simple and decisive experiment is to mingle a pound of ice in small frag- ments with a pound of water at 172. Its liquefaction is instantly accomplished, but the temperature of the mixture is only 32. Therefore 140 of heat seem to have disap- peared. Had we mixed a pound of ice-cold water with a pound of water at 172, the re- sulting temperature would have been 102, proving that the 70 which had left the hotter portion, were manifestly transferred to that which was cooler. The converse of the pre- ceding experiments may also be demonstrated ; for on suspending a flask of water, at 35 for example, in an atmosphere at 20, if it cool to 32 in 3 minutes, it will take 140minutesHo be converted into ice of 32 ; because the heat emanating at the rate of 1 per minute, it will require that time for 140 to escape. The latter experiment, however, from the inferior conducting power of ice, and the uncertainty when all is frozen, is not susceptible of the precision which the one immediately preced- ing admits. The tenth of 140 is obviously 14; and hence we may infer, that when a certain quantity of water, cooled to 22, or 10 below 32, is suddenly caused to congeal, 1-1 4th of the weight will become solid. We can now understand how the thaw which supervenes after an intense frost, should sa slowly melt the wreaths of snow and beds of ice, a phenomenon observable in these lati- tudes from the origin of time, but whose explanation was reserved for Dr. Black. In- deed, had the transition of water from its solid into its liquid state not been accompanied by this great change in its relation to heat, every thaw would have occasioned a frightful inun- dation, and a single night's frost would have solidified our rivers and lakes. Neither animal nor vegetable life could frave subsisted under such sudden and violent transitions. Mr. Cavendish, who had discovered the above fact, before he knew of its being inculcated by Dr. Black in his lectures, states the quantity of heat which ice seems to absorb in its fusion to be 1 50 ; Lavoisier and Laplace make it 1 35 ; a number probably correct, from the pairs they took in constructing, on this basis, their calorimeter. The fixity of the melting points of bodies exposed to a strong heat need no longer surprise H'S; because till the whole mass be melted, the heat incessantly intro- duced is wholly expended in constituting liquidity, without increasing the temperature. We can also comprehend how a liquid metal, a saline solution, or water, should in the career of refrigeration sink below the term of its congelation, and suddenly remount to it. Those substances, in which the attractive force that reverts the poles into the solid arrange- ment acts most slowly or feebly, will most readily permit this depression of temperature, before liquidity begins to cease. Thus bis- muth, a brittle metal, takes 8 of cooling below its melting point, to determine its solidification ; tin takes 4 ; but lead passes so readily into the solid arrangement that its cooling is at once arrested at its fusing tem- perature. In illustration of this statement, we may remark, that the particles of bismuth and tin lose their cohesive attraction in a great measure long before they are heated to the melting point ; though lead continues rela- tively cohesive till it begins to melt. Tin may be easily pulverized at a moderate eleva- tion of temperature, and bismuth in its cold state. The instant, however, that these two metals, when melted, begin to congeal, they CAL 277 CAL nse to the proper fusing temperature, because ihe caloric of liquidity is then disengaged. Drs. Irvine, father and son, to both of whom the science of heat is deeply indebted, investigated the proportion of caloric disen- gaged by several other bodies in their passage from the liquid to the solid state, and obtained the following results : 27-14 5-6 Caloric of liquidity. Sulphur, 14368 Spermaceti, 1 45- Lead, 162- Bees' wax, 175- Zinc, 493- 48-3 Tin, 500- 33- Bismuth, 550- 23-25 The quantities in the second column are the degrees by which the temperatures of each of the bodies, in its solid state, would have been raised by the heat disengaged during its concretion. An exception must be made for wax and spermaceti ; which are supposed to be in the fluid state, when indicating the ubove elevation. Dr. Black imagined that the new relation to heat which solids acquire by liquefaction, was derived from the absorp- tion, and intimate combination, of a portion of that fluid, which thus employing all its re- pulsive energies in subduing the stubborn force of cohesion, ceased to have any ther- mometric tension, or to be perceptible to our senses. He termed this supposed quantity of caloric, their latent heat ; a term very conve- nient and proper, while we regard it simply as expressing the relation which the calorific agent bears to the same body in its fluid and solid states. To the presence of a certain portion of latent or combined heat in solids, Dr. Black ascribed their peculiar degrees of soft- ness, toughness, malleability. Thus we know that the condensation of a metal by the ham- mer, or under the die, never fails to render it brittle, while, at the same time, heat is disen- gaged. B^rthollet subjected equal pieces of copper and silver to repeated strokes of a fly press. The elevation of their temperature, which was considerable by the first blow, di- minished greatly at each succeeding one, and became insensible whenever the condensation of volume ceased. The copper suffered greatest condensation, and evolved most heat. Here the analogy of a sponge, yielding its water to pressure, has been employed to illustrate the materiality of heat supposed deducible from these experiments. But the phenomenon may be referred to the intestine actions between the ultimate particles which must accompany the violent dislocation of their attracting poles. The cohesiveness of the metal is greatly im- paired. The enlarged capacity for heat, to use the popular expression, which solids acquire in .liquefying, enables us to understand and apply the process of artificial cooling, by what are called freezing mixtures. When two solids, such as ice and salt, by their reciprocal affinity give birth to a liquid, then a very great de- mand for heat is made on the surrounding bodies, or they are powerfully stripped of their heat, and their temperature sinks of course. Pulverulent snow and salt mixed at 32, will produce a depression of the ther- mometer plunged into them of about 38. The more rapid the liquefaction, the greater the cold. Hence the paradoxical experiment of setting a pan on the fire containing the above freezing mixture with a small vessel of water plunged into it. In a few seconds the water will be found to be frozen. The solu- tion of all crystallized salts is attended with a depression of temperature, which increases generally with the solubility of the salt. The Table of Freezing Mixtures in the APPENDIX, presents a copious choice of such means of refrigeration. Equal parts of sal ammoniac and nitre, in powder, form the most convenient mixture for procuring mo- derate refrigeration ; because the water of solution being afterwards removed by evapo- ration, the pulverized salts are equally effica- cious as at first. Under the articles CLIMATE, CONGELATION, TEMPERATURE, THER- MOMETER, and WATER, some additional facts will be found on the present subject. But the diminution of temperature by liquefaction is not confined to saline bodies. When a solid amalgam of bismuth, and a solid amalgam of lead, are mixed together, they become fluid, and the thermometer sinks during the time of their action. According to Dobereiner, if 118 grains of tin filings, 207 of lead filings, and 284 grains of pulverized bismuth (the constituents of his fusible metal), be incorporated in a dish of ca- lendered paper, with 161 -6 grains of mercury, the temperature instantly sinks from 65 to 14 .He thinks that it would sink even so low as the freezing point of mercury, were the experiment performed in a temperature some- what under 32. In like manner, when 816 grains of amal- gam of lead (404 mercury + 412 lead) were mixed in a temperature of 68, with 688 grains of the amalgam of bismuth (404 mer- cury -}- 284 bismuth), the temperature sud- denly fell to 30, and by the addition of 808 grains of mercury (also at 68), it became as low as 17, the total depression being therefore 51. Ann. of Phil N. S. ix. 389. The equilibrium between the attractive and repulsive forces, which constitutes the liquid condition of bodies, is totally subverted by a definite elevation of temperature, %vhen the external compressing forces do not vary. The transition from the liquid state into that of elastic fluidity, is usually accompanied with certain explosive movements, tenned ebulli- tion. The peculiar temperature at which different liquids undergo this change is there- fore called their boiling point ; and the resulting elastic fluid is termed a vapour, to distinguish CAL 278 CAL it from a gas, a substance permanently elastic, and not condensible as vapours are, by mo- derate degrees of refrigeration. It is evident that when the attractive forces, however feeble in a liquid, are supplanted by strong repulsive powers, the distances between the particles must be greatly enlarged. Thus a cubic inch of water at 40 becomes a cubic inch and l-25th on the verge of 212, and at 212 it is converted into 1694 cubic inches of steam. The existence of this steam indicates a balance between its elastic force and the pressure of the atmosphere. If the latter be increased beyond its average quantity by natural or artificial means, then the elasticity of the steam will be partially overcome, and a portion of it will return to the liquid condition. And conversely, if the pressure of the air be less than its mean quantity, liquids will assume elastic fluidity by a less intensity of calorific repulsion, or at a lower thermometric tension. Professor Robison performed a set of ingenious experiments, which appear to prove, that when the atmospheric pressure is wholly withdrawn, that is, in vacua, liquids become elastic fluids 124 below their usual boiling points. Hence water in vacua will boil and distil over at 212 124 :=88 Fahr. This principle was long ago employed by the celebrated Watt in his researches on the steam-engine, and has been recently applied in a very ingenious way by Mr. Tritton in his patent still, (Phil. Mag. vol. 51.), and Mr. Barry, in his eva- porator for vegetable extracts, (Med. Chir. Trans, vol. 10.) See ALCOHOL, DISTIL- LATION, EXTRACT. On the same principle of the boiling vary- ing with the atmospheric pressure, the Rev. Mr. Wollaston has constructed his beautiful thermometric barometer for measuring heights. He finds that a difference of 1 in the boiling point of water is occasioned by a difference of 0-589 of an inch on the barometer. This corresponds to nearly 520 feet of difference of elevation. By using the judicious directions which he has given, the elevation of a place may thus be rigorously determined, and with great convenience. The whole apparatus, weighing 20 ounces, packs in a cylindrical tin case, 2 inches diameter, and 10 inches long. When a vessel containing water is placed over a flame, a hissing sound or simmering is soon perceived. This is ascribed to the vibra- tions occasioned by the successive vaporization and condensation of the particles in immediate contact with the bottom of the vessel. The sound becomes louder as the liquid is heated, and terminates in ebullition. The temperature becomes now of a sudden stationary when the vessel is open, however rapidly it rose before, and whatever force of fire be applied. Dr. Black set a tin cup full of water at 50, on a red hot iron plate. In four minutes k reached the boiling point, and in twenty minutes it >-*was all boiled off. From 50 to 212, the elevation is 162 ; which interval, divided by 4, gives 40^ of heat, which entered the tin cup per minute. Hence 20 minutes, or 5 times 4 multiplied into 40^=810, will represent the quantity of heat that passed into the boiling water to convert it into a vapour. But the temperature of this is still only 212. Hence, according to Black, these 810 have been ex- pended solely in giving elastic tension, or, according to Irvine, in supplying the vastly increased capacity of the aeriform state ; and therefore they may be denominated latent heat, being insensible to the thermometer. The more exact experiments of Mr. Watt have shown, that whatever period be assigned for the heating of a mass of water from 50 to 212, 6 times this period is requisite with a uniform heat for its total vaporization. But 6 X 162=972^the latent heat of steam; a result which accords with my experiments made in a different way, as will be presently shown. Every attentive operator must have observed the greater explosive violence and apparent difficulty of the ebullition of water exposed to a similar heat in glass, than in me- tallic vessels. M. Gay Lussac has studied this subject with his characteristic sagacity. He discovered that water boiling in a glass vessel has a temperature of 214.2, and in a tin vessel contiguous to it, of only 212. A few particles of pounded glass thrown into the for- mer vessel, reduced the thermometer plunged in it to 212.6, and iron filings to 212. When the flame is withdrawn for a few seconds from under a glass vessel of boiling water, the ebul- lition will recommence on throwing in a pinch of iron filings. Professors Munche and Gmelin of Heidel- berg have extended these researches, and given the curious results as to the boiling points, expressed in the following table : Substance of the .vessels. Ther. touching bottom. Do. J inch below sur- face of the water. Silver, 211-775 211- 55 Platina, 211-775 210-875 Copper, 212-900 212-225 Tinned iron, 213- 24 211- 66 Marble, 212- 10 211- 66 Lead, 212- 45 21L775 Tin, 212- 7 211-775 Porcelain, 212- 1 211-900 White glass, 212- 7 212- 00 Green glass, 213- 8 213- 35 Ditto, 212- 7 212- 00 Delft ware, 213. 8 212- 7 Common earthen ware, 213- 8 212- 45 It is difficult to reconcile these variations to the results of M. Gay Lussac. " The vapour formed at the surface of a liquid," he remarks, " may be in equilibria with the atmospheric pressure ; while the interior portion may ac- quire a greater degree of heat than that of the real boiling point, provided the fluid be en- CAL 279 CAL closed in a vessel, and heated at the bottom. In this case, the adhesion of the fluid to the vessel may be considered as analogous in its action to viscidity, in raising the temperature of ebullition. On this principle we explain the sudden starts which sometimes take place in the boiling of fluids. This frequently occurs to a great degree in distilling sulphuric acid, by which the vessels are not unfrequently broken when they are of glass. This evil may be effectually obviated by putting into the retort some small pieces of platina wire, when the sudden disengagement of gas will be pre- vented, and consequently the vessels not be liable to be broken." Annalcs de Chimie, March 1818. See my remarks on this sub- ject under the DISTILLATION of SULPHU- RIC ACID, extracted from the Journal of Science, October 1817- If we throw a piece of paper, a crust of bread, or a powder, into a liquid slightly impregnated with carbonic acid, its evolution will be determined. See some curious observations by M. Thenard under our articles OXYGENIZED NITRIC ACID, or OXYGENIZED WATER. In a similar manner, the asperities of the surface of a glass or other vessel, act like points in elec- tricity in throwing off" gas or vapour present in the liquid which it contains. In all the examples of the preceding table, the temperature is greater at the bottom than near the surface of the liquid ; and the specific differences must be ascribed to the attractive force of the vessel to water, and its conduction of heat. We must thus try to explain why tinned iron gives a temperature to boiling water in contact with it, 1-67 degrees higher than silver and platina. Between water, and iron, tin, or lead, there are reciprocal relations at elevated temperatures, which do not appa- rently exist with regard to silver and platina. M. Clement informed me in 1 82 1 , that when steam, at 212, was made to act on sugar, or a saline powder, as that of nitre or common salt, a temperature was produced considerably greater than the steam, and, generally speak- ing, equal to that of a boiling hot saturated solution of the particular salt. This curious subject has been recently investigated by Mr. Farraday. The simplest way of recognising the above phenomenon is, to hold in the steam issuing from the spout of a tea-kettle, a thermometer bulb, covered with a little pow- dered sal ammoniac, or nitre. The temperature indicated is from 230 to 240. The following are the temperatures produced in this way, by some substances. The first column denotes the temperatures obtained in the above me- thod ; the second, those obtained by tying the bulb up with the substance in a piece of flannel, or lint, and plunging it into an atmo- sphere of steam : Sugar, 216 223 Muriate of ammonia, 230 227 Citric acid, 230 228 Nitric acid, 232 230 Nitrate of magnesia, 236 236 Nitrate of ammonia, 236 240 Acetate of potash, 244 258 Subcarbonate of potash, 258 262 Potash, 300 and upwards. M. Gay Lussac has remarked, that the tem- perature of vapour is that of the hot solution from which it rises. Journal of Science, xiv. 439. The following is a tabular view of the boiling points by Fahrenheit's scale of the most important liquids, under a mean baro- metrical pressure of thirty inches : Boiling points. Ether, sp. gr. 0-7365 at 48". G. Lussac, 100 Sulphate of magnesia, Tartrate of potash, Taitaric acid, 218 214 236 230 226 221 Carburet of sulphur, do. 113 Alcohol, sp. gr. 0-813 Ure, 173-5 Nitric acid, 1-500 Dalton, 210 Water, 212 Saturated sol. of Glaub. salt, Biot, 213-t Do. do. sugar of lead, do. 215f Do. sea salt, do. 224| Muriate of lime 1 -j- water 2 Ure, 230 Do. 35-5 + do. 64-5 do. 235 Do. 40-5 + do. 59-5 do. 240 Muriatic acid, 1-094 Dalton, 232 Do. 1-127 do. 222 Do. -047 do. 222 Nitric acid, -45 do. 240 Do. -42 do. 248 Do. -40 do. 247 Do. -35 do. 242 Do. -30 do. 236 Do. -16 do. 220 Rectified petroleum, >.. Ure, 306 Oil of Turpentine, . do. 316 Sulph. acid, sp. gr. 1-30 -j- Dalton, 240 Do. 1-408 do. 260 Do. 1-520 do. 290 Do. 1-650 do. 350 Do. 1-670 do. 360 Do. 1-699 do. 374 Do. 1-730 do. 391 Do. 1-780 do. 435 Do. 1-810 do. 473 Do. 1-819 do. 487 Do. 1-827 do. 501 Do. 1-833 do. 515 Do. 1-842 do. 545 Do. 1-847 do. 575 Do. 1-848 do. 590 Do. 1-849 do. 605 Do. 1-850 do. 620 Do. 1-848 Ure, 600 Phosphorus, 554 570 Linseed oil, . . . 640 Mercury, (Dulong, 662), . 656 These liquids emit vapours, which, at their CAL 280 CAL respective boiling points, balance a pressure of the atmosphere equivalent to thirty vertical inches of mercury. But at inferior tempera- tures they yield vapours of inferior elastic power. It is thus that the vapour of quick- silver rises into the vacuum of the barometer tube ; as is seen particularly in warm climates, by the mercurial dew on the glass at its sum- mit. Hence aqueous moisture adhering to the mercury, causes it to fall below the true ba- rometer level, by a quantity proportional to the temperature. The determination of the elastic force of vapours, in contact with their respective liquids, at different temperatures, has been the subject of many experiments. The method of measuring their elasticities, described in my paper on HEAT, seems con- venient, and susceptible of precision. A glass tube about -| of an inch internal diameter, and 6 feet long, is sealed at one end, and bent with a round curvature in the mid- dle, into the form of a syphon, with its two legs parallel, and about 2^ inches asunder. A rectangular piece of cork is adapted to the interval between the legs, and fixed firmly by twine, about 6 inches from the ends of the syphon. Dry mercury is now introduced, so as to fill the sealed leg, and the bottom of the curvature. On suspending this syphon ba- rometer in a vertical direction, by the cork, the level of the mercury will take a position in each of the legs, corresponding to the pres- sure of the atmosphere. The difference is of course the true height of the barometer at the time, which may be measured by the applica- tion of a separate scale of inches and tenths. Fix rings of fine platinum wire round the tube at the two levels of the mercury. Introduce now into the tube a few drops of distilled water, recently boiled, and pass them up through the mercury. The vapour rising from the water will depress the level of the mercury in the sealed leg, and raise it in the open leg, by a quantity equal in each to one- half of the real depression. To measure distinctly this difference of level with minute accuracy, would be difficult ; but the total depression, which is the quantity sought, may be readily found, by pouring mercury in a slender stream into the open leg, till the surface of the mercury in the sealed leg becomes once more a tangent to the platina ring, which is shown by a delicate film of light, as in the mountain barometer. The vertical column of mercury above the lower initial level being measured, it represents precisely the elastic force of the vapour, since that altitude of mercury was required to overcome the elasticity of the vapour. The whole object now is to apply a regulated heat to the upper portion of the sealed leg, from an inch below the mer- curial level to its summit. This is easily ac- complished, by passing it through a perforated cork into an inverted phial, 5 inches diameter and 7 long, whose bottom has been previously cracked off by a hot iron. Or a phial may be made on purpose. When the tapering elastic cork is now strongly pressed into the mouth of the bottle, it renders it perfectly water-tight. By inclining the syphon, we remove a little of the mercury, so that when reverted, the level in the lower leg may nearly coincide with the ring. Having then suspended it in the ver- tical position from a high frame, or the roof of an apartment, we introduce water at 32 into the cylindrical glass vessel. When its central tube, against the side of which the bulb of a delicate thermometer rests, acquires the temperature of the surrounding medium, mer- cury is slowly added to the open leg, till the primitive level is restored at the upper platina ring. The column of mercury above the ring in the open leg, is equivalent to the force of aqueous vapour at 32. The effect of lower temperatures may be examined, by putting saline freezing mixtures in the cylinder. To procure measures of elastic force at higher temperatures, two feeble Argand flames are made to send up heated air on theopposite shoul- ders of the cylinder. By adjusting the flames and agitating the liquid, very uniform tempera- tures may be given to the tube in the axis. At every 5 or 10 of elevation, we make a measure- ment, by pouring mercury into the open leg, till the primitive level is restored in the other. For temperatures above 212, I em ploy the same plan of apparatus, slightly modified. The sealed leg of the syphon has a length of 6 or 7 inches, while the open leg is 10 or 12 feet long, secured in the groove of a graduated wooden prism. The initial level becomes 212 when the mercury in each leg is in a horizontal plane, and the heat is now communicated through the medium of oil. If the bending of the tube be made to an angle of about 35 from parallelism of the legs, a tubulated glo- bular receiver becomes a convenient vessel for holding the oil. The tapering cork through which the sealed end of the syphon is passed, being thrust into the tapering mouth of the receiver, remains perfectly tight at all higher temperatures, being progressively swelled with the heat. One who has not made such trials may be disposed to cavil at the probable tight- ness of such a contrivance ; but I who have used it in experiments for many months to- gether, know that only extreme awkwardness in the operator can occasion the dropping out of oil heated up to even 320 of Fahrenheit. The tubulure of the receiver admits the ther- mometer. The Tables of Vapour, in the Ap- pendix, exhibit the results of some carefully conducted experiments. See VAPOUR. In my attempts to find some ratio which would connect the above elasticities of aqueous vapour with the temperatures, the following rule occurred to me : " The elastic force at 21 2 = 30 being di- vided by 1.23, will give the force for 10 below; this quotient divided by 1.24, will give that 10 lower, and so on progressively. To obtain the forces above 212, we have CAL 281 CAL merely to multiply 30 by the ratio 1-23 for the force at 222; this product by 1.22 for that at 232<>, this last product by 1.21 for the force at 242, and thus for each successive interval of 10 above the boiling point." The following modification of the same rule gives more accurate results. c< Let r the mean ratio between that of 210 and the given tem- perature ; n the number of terms (each of 10) distant from 210; F = the elastic force of steam in inches of mercury. Then Log. of F =. Log. 28.9 rt n Log. r ; the positive sign being used above, the negative below 210." 1 have investigated also simple ratios, which express the connexion between the temperature and elasticity of the vapours cf alcohol, ether, petroleum, and oil of turpentine, for which I must refer to the paper itself. Mr. W. Creighton of Soho communicated, in March 1819, to the Philosophical Maga- zine, the following ingenious formula for aqueous vapour. Let the degrees of Fahren- heit -f- 85 D, and the corresponding force of steam in inches of mercury 0.09 = I. Then Log. D 2.22679 X 6 = Log. I. EXAMPLE. 212 + 85 = 297 Log. = 2.47276 2.22679 constant number. Log. 1.47582=29.91=1 +0.09 Inches 30.00 D He then gives a satisfactory tabular view of the near correspondences between the results of his formula, and my experiments. By determining experimentally the volume of vapour which a given volume of liquid can produce at 212, M. Gay Lussac has happily solved the very difficult problem of the spe- cific gravity of vapours. He took a spherule of thin glass, with a short capillary stem, and of a known weight. He filled it with the pe- culiar liquid, hermetically sealed the orifice, and weighed it. Deducting from its whole weight the known weight of the spherule, he knew the weight, and from its sp. gravity the bulk of the liquid. He filled a tall graduated glass receiver, capable of holding about three pints, with mercury, inverted it in a basin, and let up the spherule. The receiver was now surrounded by a bottomless cylinder, which rested at its lower edge in the mercury of the basin. The interval between the two cylinders was filled with water. Heat was applied by means of a convenient bath, till the water and the included mercury assumed the temperature of 212. The expansible liquid had ere this burst the spherule, expanded into vapour, and depressed the mercury. The height of the quicksilver column in the gra- duated cylinder above the level of the basin, being observed, it was easy to calculate the volume of the incumbent vapour. The quan- tity of liquid used was always so small, that the whole of it was converted into vapour. The following exhibits the specific gravities as determined by the above method : Vapour of water, - 0.62349 Hydroprussic acid, 0.94760 Absolute alcohol, 1.6050 Sulphuric ether, 2.5860 Hydriodic ether, 5-4749 Oil of turpentine, 5.0130 Carburet of sulphur, 2.6447 Muriatic ether, 2.2190 Spec. Grav. Air at 2l2o, = i Boiling point, Fahr. Thenard, 212 79-7 173 96 148 316 116 52 The above specific gravities are estimated under a barometric pressure of 29.92 inches. M. Gay Lussac has remarked, that when a liquid combination of alcohol and water, or alcohol and ether, is converted into vapour at 212o Fahr. or 100 Cent., the volume is ex- actly the sum of what their separate volumes would have produced ; so that the condensa- tion by chemical action in the liquid state, ceases to operate in the gaseous. An equal volume of carburet of sulphur and absolute alcohol, at their respective boiling points of 173 and 126, is said to yield each an equal quantity of vapour of the same density. A more explicit statement has been promised, and is perhaps required on this curious subject. It appears, that a volume of water at 40 forms 1694 volumes of steam at 212. The subsequent increase of the volume of steam, and of other vapours, out of the contact of their respective liquids, we formerly stated to be in the ratio of the expansion of gases, forming an addition to their volume of 3-8ths for every 180 Fahrenheit. We can now infer, both from this expansion of one measure into 1694, and from the table of the elastic forces of steam, the explosive violence of this agent at still higher temperatures, and the danger to be apprehended from the introduction of water into the close moulds in which melted metal is to be poured. Hence, also, the formidable accidents which have happened, from a little CAL CAL water falling into heated oils. The little glass spherules, called candle bombs, exhibit the force of steam in a very striking manner ; but the risk of particles of glass being driven into the eye, should cause their employment to be confined to prudent experimenters. Mr. Watt estimated the volumes of steam resulting from a volume of water at 1800; and in round numbers at 1728 ; numbers differing little from the above determination of M. Gay Lussac. Desaguliers' estimate of 14000 was therefore extravagant. M. le Baron Cagniard de la Tour has lately described several curious facts concern- ing the production of vapours in close vessels. It had been hitherto imagined that when a liquid is confined in a Papin's digester, the internal pressure augmenting with the pressure eventually prevents the further transition of the liquid into the aeriform condition. It oc- curred to him that there was necessarily a limit to the dilatation of a volatile fluid, beyond which it would become vapour, notwithstand- ing the pressure, if the capacity of the vessel would permit the liquid matter to extend to its maximum of dilatation. To ascertain this point, a certain quantity of alcohol, sp. gr. 0.837, and a sphere of silex, were put into a small digester, made out of the thick end of a musket barrel, the liquid occupying the third of the capacity. Having observed the sound produced by the sphere, when rolled about in the cold apparatus, it was gradually heated till a point was reached when the ball seemed to bound from end to end of the digester, as if no liquid had been present. This effect, easily distinguished by holding the end of the handle to the ear, ceased on cooling the apparatus, and was re- produced on re-heating it. The same experiment made with water succeeded only imperfectly, because the high temperature required interfered with the light- ness of the instrument. But sulphuric ether and naphtha presented the same results as al- cohol. That the phenomena might be observed with more facility, the liquids were introduced into small tubes of glass, and hermetically sealed. A handle of glass was attached to each tube. A tube was two fifths filled with alcohol, and then slowly and carefully heated ; as the liquid dilated its mobility increased, and when its volume was nearly doubled, it completely disappeared, and became a vapour so transparent, that the tube appeared quite empty. On leaving it to cool for a moment, a very thick cloud formed in its interior, and the liquid returned to its first state. A second tube, nearly half occupied by the same fluid, gave a similar result ; but a third, containing rather more than half, burst. Similar experiments made with naphtha, sp. gr. 0.807, n d with ether, gave similar results. Ether required less space than naphtha, and naphtha less than alcohol, to become va- pour ; appearing to indicate that the more a body is already dilated, the less additional volume does it require, before it attains its maximum of expansion. In all the above experiments the air had been expelled from the tubes ; but, repeated with others in which the air was left, the re- sults were similar, and the phenomena more readily observed, from the absence of ebulli- tion. A last trial was made with water in a tube of glass, about one third of its capacity being occupied by the fluid. This tube lost its transparency, and broke a few instants after. It appears that by a high temperature, water is able to decompose glass, by separating the alkali ; leading to the supposition that other interesting chemical results may be obtained, by multiplying the applications of this process of decomposition. On carefully watching the tubes in which air had been left, it was remarked that those in which the fluid had not space for the max- imum of dilatation preceding the conversion into vapour, did not always break as soon as the liquid appeared to fill the whole space ; and that the explosion was the more tardy, as the excess of liquid above that required to fill the space, was less. May not then the in- ference be drawn, that liquids but little com- pressible at low temperatures, become much more so at high temperatures ? Alcohol, naphtha, and sulphuric ether, sub- mitted to heat with pressure, are converted into vapour in a space a little more than double that of each liquid. An augmentation of pressure, occasioned by the presence of air, causes no obstacle to the evaporation of the liquid in the same space, but only renders the dilatation of the liquid more regular and observable. Water, though susceptible of being reduced into very compressed vapour, has not yet been submitted to perfect experiments, because of the imperfect closing of the digester at high temperatures, and also because of its action on glass tubes. M. Cagniard de la Tour bent a tube into a syphon, placed ether in one leg, and separated it from the other leg containing air, by mer- cury ; both legs being then sealed, the appa- ratus was heated, and when the ether became vapour, the diminution in the bulk of the air was marked. In three repetitions of the ex- periment 528 parts became 14. Ether is therefore susceptible of being converted into vapour in a space less than twice its original volume, and in this state it exercises a pressure of between 37 and 38 atmospheres. When alcohol, sp. gr. 0.837, was used, 476 parts of air became 4 ; and from an ob- servation of the volume, it was ascertained that alcohol may be reduced into vapour, in a space rather less than thrice its original vo- CAL 283 CAL iume, and that then it exerts a pressure of 1 19 atmospheres. The temperature at which these effects took place was ascertained, by repeating the experi- ments in an oil bath. The ether required a temperature of 320 F. ; alcohol, that of 405F. A small quantity of carbonate of soda added to the water, prevented, to a certain degree, its altering the transparency of the glass tubes. Hence he was enabled to ascertain that at a temperature not far from that of melting zinc, water could be converted into vapour, in a space nearly four times its original volume. Annales de Chimie, xxi. 178. It has been already mentioned, that the caloric of fluidity in steam surpasses that of an equal weight of boiling water by about 972. This quantity, or the latent heat of steam, as it is called, is most conveniently determined, by transmitting a certain weight of it into a given weight of water, at a known temperature, and from the observed elevation of temperature in the liquid deducing the heat evolved during condensation. Dr. Black, Mr. Watt, La- voisier, Count Rumford, Clement, and De- sormes, as well as myself, have published ob- servations on the subject. " In this research I employed a very simple apparatus ; and with proper management, I believe, it is capable of giving the absolute quantities of latent heat in different vapours, as exactly as more refined and complicated mechanisms. At any rate, it will afford comparative results with great precision. It consisted of a glass retort of very small dimensions, with a short neck, inserted into a globular receiver of very thin glass, and about three inches in diameter. The globe was surrounded with a certain quan- tity of water at a known temperature, con- tained in a glass basin. 200 grains of the liquid, whose vapour was to be examined, were introduced into the retort, and rapidly distilled into the globe by the heat of an Argand lamp; The temperature of the air was 45, that of the water in the basin from 42 to 43, and the rise of temperature oc- casioned by the condensation of the vapour never exceeded that of the atmosphere by four degrees. By these means, as the com- munication of heat is very slow between bodies which differ little in temperature, I found that the air could exercise no perceptible influence on the water in the basin during the experi- ment, which was always completed in five or six minutes. A thermometer of great delicacy was continually moved through the water ; and its indications were read off, by the aid of a lens, to small fractions of a degree. " In all the early experiments of Dr. Black on the latent heat of common steam, the neglect of the above precautions introduced material errors into the estimate. Hence that distin- guished philosopher found the latent heat of steam to be no more than 800 or 810. Mr. Watt afterwards determined it more nearly at from 900 to 970, Lavoisier and Laplace have made it 1000, and Count Rumford 1040. " From the smallness of the retort in my mode of proceeding, the shortness of the neck, and its thorough insertion into the globe, we prevent condensation by the air in transitu ; while the surface of the globe, and the mass of water being great, relative to the quantity of vapour employed, the heat is entirely trans- ferred to the refrigeratory, where it is allowed . to remain without apparent diminution for a few minutes. " In numerous repetitions of the same ex- periment the accordances were excellent. The following table contains the mean results. The water in the basin weighed in each case 32340 grs., and 200 grs. of each liquid was distilled over. The globe was held steadily in the centre of the globe by a slender ring fixed round the neck." For the arithmetical re- ductions I must refer to the paper itself. But I have found since, that a compensation was due for the glass basin itself, which I omitted by accident to introduce into the arithmetical reductions. This would have raised the latent heat of water to very nearly 1000, and that of the other vapours in a proportional degree. I now give the original table along with a cor- rected column: Talk of Latent Heat of Vapours. Vapour of water, at its boiling point Alcohol, sp. gr. 825 Ether, boiling point 112 Petroleum Oil of turpentine Corrected Column. 967 442 302.4 177-8 177.8 Nitric acid, sp. gr. 1.494, boiling point 165 532. Liquid ammonia, sp. gr. 0.978 . 837.3 Vinegar, sp. gr. 1.007 875.0 1000 457 312.9 183.8 183.8 550. 865-9 903 " Aqueous vapour of an elastic force ba- of water unity, or 1.00 ; then the specific gra- lancing the atmospheric pressure, has a spe- vity of the vapour of pure ether is 4.00, while cific gravity compared to air, by the accurate the specific gravity of the vapour of absolute experiments of M. Gay Lussac, of 10 to 16. alcohol is 2.60. But the vapour of ether, For facility of comparison, let us call the steam whose boiling point is not 100, but 1 12, like CAL 284 CAL the above ether, contains some alcoliol ; hence we must accordingly diminish a little the specific gravity number of its vapour. It will then be- come, instead of 4.00, 3.55. Alcohol of 0.825 sp, gr. contains much water ; sp. gr. of its va- pour, 2.30. That of water, as before unity, 1.00. The interstitial spaces in these vapours will therefore be inversely as these numbers, or sis for ether ^o for alcohol, ^ for water. Hence, -^ of latent heat existing in ethereal vapour, will occupy a proportional space, be equally condensed, or possess the same tension with ^ in alcoholic, and -^ in aqueous vapour. A small modification will no doubt be introduced by the difference of the thermo- metric tensions, or sensible heats, under the same elastic force. Common steam, for ex- ample, may be considered as deriving its total elastic energy from the latent heat multiplied into the specific gravity -f the thermometric tension. " Hence, the elastic force of the vapours of water, ether, and alcohol, are as follows : E w = 970 X 1.00 -f 212" = 1182 E e = 302 X 3.55 -f- 112" = 1184 E al = 440 X 2.30 + 175 = 1185 Three equations, which yield, according to my general proposition, equal quantities. When the elastic forces of vapours are doubled, or when they sustain a double pressure, their in- terstices are proportionably diminished. We may consider them now, as in the condition of vapours possessed of greater specific gravities. Hence the second portion of heat introduced to give double the elastic force, need not be equal to the first, in order to produce the double tension. "This view accords with the experiments of Mr. Watt, alluded to in the beginning of the memoir. He found, that the latent heat of steam is less when it is produced under a greater pressure, or in a more dense state; and greater when it is produced under a less pressure, or in a less dense state. Berthollet thinks this fact so unaccountable, that he has been willing to discard it altogether. Whether the view I have just opened, of the relation subsisting between the elastic force, density, and latent heat of different vapours, harmonize with chemical phenomena in general, I leave others to determine. It certainly agrees with that unaccountable fact. Whatever be the fate of the general law now respectfully offered, the statement of Mr. Watt may be implicitly received under the sanction of his acknow- ledged sagacity and candour." lire's Re- searches on Heat, pp. 54 and 55. M. Clement inserted a pipe connected with a steam boiler capable of bearing high pres- sure into a given quantity of water at a certain temperature, contained in a bucket. He now turned the stop-cock on the pipe, and allowed a certain quantity of steam at 212 F. to enter. He then noted the increase of temperature which the water had received. He repeated the experiment ; only the steam in the boiler and that which issued through the pipe, had been heated till its elasticity was double of that at 212 U . As soon as the water in the bucket indicated, by its increase of volume, that the same quantity of steam had been condensed as in the first experiment, he shut the stop-cock and measured the temperature of the bucket. He found it to be the same as before. A third experiment with steam having an elastic force equal to three atmospheres, was next subjected to examination ; and he found the same result. Hence he inferred that equal weights of steam, incumbent over water, at whatsoever temperature, contain the same quantity of heat ; or, in popular language, that the total heat of steam is a constant quantity : for, in proportion as the sensible heat augments, the latent or specific heat di- minishes. On this proposition he has founded a luminous theory of steam engines, which, we hope, he will soon present to the world in his promised Traite de Clialcur. As it is the vastly greater relation to heat which steam possesses above water, that makes the boiling point of that liquid so perfectly stationary in open vessels, over the strongest fires, we may imagine that other vapours which have a smaller latent heat, may not be capable, by their formation, of keeping the ebullition of their respective liquids at a uni- form temperature. I observed this variation of the boiling point actually to happen with oil of turpentine, petroleum, and sulphuric acid. When these liquids are heated briskly in apothecaries' phials, they rise 20 or 30 de- grees above the ordinary point at which they boil in hemispherical capsules. Hence, also, their vapours being generated with little heat, are apt to rise with explosive violence. Oil of turpentine varies, moreover, in its boiling point, according to its freshness and limpidity. It is needless, therefore, to raise an argument on a couple of degrees of difference. But, in Dr. Murray's, and all our other chemical sys- tems published prior to 1817, 560 was as- signed as the boiling point of this volatile oil. Mr. Daltgn's must be excepted, for he says, " several authors have it, that oil of turpentine boils at 560. I do not know how the mis- take originated, but it boils below 212, like the rest of the essential oils." From the above quotation, it may be in- ferred, that the conversion at all temperatures, however low, of any liquid or solid whatever, into a vapour, is uniformly accompanied with the abstraction of heat from surrounding bo- dies, or in popular language, the production of cold ; and that the degree of refrigeration will be proportional to the capacity of the vapour for heat, and the rapidity of its form- ation. The application of this principle lo CAL 285 CAL the uses of life, first suggested by Drs. Cullen and Black, has been improved and extended by Mr. Leslie. We shall describe his methods under CONGELATION'. It appears, moreover, probable, that the permanent gases have the same superior re- lation to heat with the vapours. Hence, their transition to the liquid or solid states ought to be attended with the evolution of heat. Ac- cordingly, in the combustion of hydrogen, phosphorus, and metals, gaseous matter is co- piously fixed ; to which cause Black and La- voisier ascribed the whole of the heat and light evolved. We shall see, however, in the article COMBUSTION, many difficulties to the adop- tion of this plausible hypothesis. The best illustration of the common nolion as to the latent heat of gases, is afforded by the con- densed air tinder-tube ; in which mechanical compression appears to extrude from cold air, its latent stores of both heat and light. A glass tube, eight inches long, and a half inch wide, of uniform calibre, shut at one end, and fitted with a short piston, is best adapted for the exhibition of this pleasing experiment. When the object, however, is merely to kindle agaric tinder, a brass tube 3-8ths wide and 4j inches long will suffice. A dexterous con- densation of air into l-5th of the volume, produces the heat of ignition. Under the head of specific heat, it has been shown to diminish in a gas more rapidly than the diminution of its volume ; and therefore heat will be disengaged by its condensation, whether we regard the phenomenon as the ex- pulsion of a fluid, or intense actions excited among the particles by their violent approxi- mation. The converse of the above pheno- menon is exhibited on a great scale, in the Schemnitz mines of Hungary. The hydraulic machine for draining them consists essentially of two strong air-tight copper cylinders, 96 feet vertically distant from each other, and connected by a pipe. The uppermost, which is at the mouth of the pit, can be charged with water by the pressure of a reservoir, elevated 13G feet above it. The air suddenly dislodged by this vast hydrostatic pressure, is condensed through the pipe, on the surface of the water standing in the lower cylinder, which it -forces up a rising water-pipe to the surface, and then takes its place. When the stop- cocks are turned to recharge the lower cylin- der with water, the imprisoned air expanding to its natural volume, absorbs the heat so powerfully, as to convert the drops of water that issue with it into hail and snow. M. Gay Lussac has lately proposed a miniature imitation of this machine for artificial refri- geration. He exposes the small body to be cooled to a stream of air escaping by a small orifice, from a box in which it had been strongly condensed. In the autumn of 1816, I per- formed an analogous experiment in the house of M. Breguet, in Paris. This celebrated artist having presented me with one of his ele- gant metallic thermometers, I immediately proposed to determine, by means of it, the heat first abstracted, and subsequently disen- gaged in the exhaustion of air, and its re- admission into the receiver of an air-pump. MM. Breguet politely favoured me with their assistance, and the use of their excellent air- pump. Having enclosed in the receiver their thermometer, and a delicate one by Crighton, which I happened to have with me, we found, on rapidly exhausting the receiver, that M. Breguet's thermometer indicated a refrigera- tion of 50 F. while Crighton's sunk only 7. After the two had arrived at the same tem- perature, the air was rapidly admitted into the receiver. M. Breguet's thermometer now rose 50, while Crighton's mounted 7 as be- fore. See THERMOMETER. Dr. Darwin has ingeniously explained the production of snow on the tops of the highest mountains, by the precipitation of vapour from the rarefied air which ascends from plains and valleys. " The Andes," says Sir H. Davy, u placed almost under the line, rise in the midst of burning sands ; about the middle height is a pleasant and mild climate; the summits are covered with unchanging snows ; and these ranges of temperature are always distinct : the hot winds from below, if they ascend, become cooled in consequence of ex- pansion ; and the cold air, if by any force of the blast it is driven downwards, is condensed, and rendered warmer as it descends." Evaporation and rarefaction, the grand means employed by nature to temper the ex- cessive heats of the torrid zone, operate very powerfully among mountains and seas. But the level sands are devoured by unmitigated heat. In milder climates, the fervours of the solstitial sun are assuaged by the vapours co- piously raised from every river and field, while the wintry cold is moderated by the conden- sation of atmospheric vapours in the form of snow. The equilibrium of animal temperature is maintained by the copious discharge of va- pour from the lungs and the skin. The sup- pression of this exhalation is a common cause of many formidable diseases. Among these, fever takes the lead. The ardour of the body in this case of suppressed perspiration, some- times exceeds the standard of health by six or seven degrees. The direct and natural means of allaying this morbid temperature were first systematically enjoined by Dr. Currie of Li- verpool. He showed, that the dashing or affusion of cold water on the skin of a fever patient, has most sanitary effects, when the heat is steadily above 98, and when there is no sensation of chilliness, and no moisture on the surface. Topical refrigeration is elegantly procured, by applying a piece of muslin or tissue paper to any part of the skin, and moist- ening it with ether, carburet of sulphur, or CAL CAL alcohol. By pouring a succession of drops of ether on the surface of a thin glass tube con- taining water, a cylinder of ice may be formed at midsummer. The most convenient plan which the chemist can employ, to free a gas from vapour, is to pass it slowly through a long tortuous tube wrapt in porous paper wetted with ether. On the other hand, when he wishes to ex- pose his vessels to a regulated heat, he makes hot vapour be condensed on their cold surface. The heat thus disengaged from the vapour, passes into the vessel, and speedily raises it to a temperature which he can adjust with the nicest precision. A vapour bath ought there- fore to be provided for every laboratory. That which I got constructed a few years ago for the Institution, is so simple and efficacious as to merit a description. A square tin box, about 18 inches long, 12 broad, and 6 deep, has its bottom hollowed a little by the ham- mer towards its centre, in which a round hole is cut of five or six inches diameter. Into this, a tin tube three or four inches long is soldered. This tube is made to fit tightly into the mouth of a common tea-kettle, which has a folding handle. The top of the box has a number of circular holes cut into it, of differ- ent diameters, into which evaporating capsules of platina, glass, or porcelain, are placed. When the kettle, filled with water, and with its nozzle corked, is set on a stove, the vapour, playing on the bottoms of the capsules, heats them to any required temperature ; and being itself continually condensed, it runs back into the kettle to be raised again, in ceaseless co- hobation. With a shade above, to screen the vapour chest from soot, the kettle may be placed over a common fire. The orifices not in use are closed with tin lids. In drying precipitates, I cork up the tube of the glass funnel, and place it, with its filter, directly into the proper sized opening. For drying red cabbage, violet petals, &c. a tin tray is provided, which fits close on the top of the box, within the rim which goes about it. The round orifices are left open when this tray is applied. Such a form of apparatus is well adapted to inspissate the pasty mass from which lozenges and troches are to be made. But the most splendid trophy erected to the science of caloric, is the steam-engine of Watt. This illustrious philosopher, from a mistake of his friend Dr. Robison, has been hitherto deprived of a part of his claims to the admiration and gratitude of mankind. The fundamental researches on the constitution of steam, which formed the solid basis of his gigantic superstructure, though they coincided perfectly with Dr. Black's results, were not drawn from them. In some conversations with which this great ornament and benefactor of his country honoured me a short period be- fore his death, he described, with delightful naivete, the simple, but decisive experiments, by which he discovered the latent heat of steam* His means and his leisure not then permitting an expensive and complex apparatus, he used apothecaries' phials. With these, he ascer- tained the two main facts, first, that a cubic inch of water would form about a cubic foot of ordinary steam, or 1728 inches; and that the condensation of that quantity of steam would heat six cubic inches of water from the atmospheric temperature to the boiling point. Hence he saw that six times the difference of temperature, or fully 900 of heat, had been employed in giving elasticity to steam ; which must be all abstracted before a complete va- cuum could be procured under the piston of the steam-engine. These practical determina- tions he afterwards found to agree pretty nearly with the observations of Dr. Black. Though Mr. Watt was then known to the Doctor, he was not on those terms of intimacy with him which he afterwards ca.ne to be, nor was he a member of his class. Mr. Watt's three capital improvements, which seem to have nearly exhausted the re- sources of science and art, were the following ; 1. The separate condensing chest, immersed in a body of cold water, and connected merely by a slender pipe with the great cylinder, in which the impelling piston moved. On open- ing a valve or stop-cock of communication, the elastic steam which had floated the pon- derous piston, rushed into the distant chest with magical velocity, leaving an almost per- fect vacuum in the cylinder, into which the piston was forced by atmospheric pressure. What had appeared impossible to all previous engineers was thus accomplished. A vacuum was formed without cooling the cylinder itself. Thus it remained boiling hot, ready the next instant to receive and maintain the elastic steam. 2. His second grand improvement con- sisted in closing the cylinder at top, making the piston rod slide through a stuffing box in the lid, and causing the steam to give the im- pulsive pressure, instead of the atmosphere. Henceforth the waste of heat was greatly di- minished. 3. The final improvement was the double impulse, whereby the power of his en- gines, which was before so great, was in a moment more than doubled. The counter- weight required in the single stroke engine, to depress the pump-end of the working beam, was now laid aside. He thus freed the ma- chine from a dead weight or drag of many hundred pounds, which had hung upon it from its birth, about seventy years before. The application of steam to heat apartments, is another valuable fruit of these studies. Safety, cleanliness, and comfort, thus com- bine in giving a genial warmth for every pur- pose of private accommodation, or public ma- nufacture. It has been ascertained, that one cubic foot of boiler will heat about two thou- sand feet of space in a cotton mill whose ave- rage 'heat is from 70 to 8d Fahr. And if CAL 287 CAM we allow 25 cubic feet of a boiler for a horse's power in a steam-engine supplied by it, such a boiler would be adequate to the warming of fifty thousand cubic feet of space. It has been also ascertained, that one square foot of surface of steam pipe, is adequate to the warm- ing of two hundred cubic feet of space. This quantity is adapted to a well-finished ordinary brick or stone building. The safety valve on the boiler should be loaded with 2 pounds for an area of a square inch, as is the rule for Mr. Watt's engines. Cast iron pipes are pre- ferable to all others for the diffusion of heat. Freedom of expansion must be allowed, which in cast iron may be taken at about a tenth of an inch for every ten feet in length. The pipes should be distributed within a few inches of the floor. Steam is now used extensively for drying muslin and calicoes. Large cylinders are filled with it, which, diffusing in the apart- ment a temperature of 100 or 130, rapidly dry the suspended cloth. Occasionally the cloth is made to glide in a serpentine manner closely round a series of steam cylinders, ar- ranged in parallel rows. It is thus safely and thoroughly dried in the course of a minute. Experience has shown, that bright dyed yarns, like scarlet, dried in a common stove heat of 128, have their colour darkened, and acquire a harsh feel ; while similar hanks, laid on a steam pipe heated up to 165, retain the shade and lustre they possessed in the wetted state. The people who work in steam drying-rooms are healthy; those who were formerly em- ployed in the stove-heated apartments, be- came soon sickly and emaciated. These in- jurious effects must be ascribed to the action of cast iron at a high temperature on the at- mosphere. The heating by steam of large quantities of water or other liquids, either for baths or manufactures, may be effected in two ways : that is, the steam pipe may be plunged with an open end into the water cistern ; or the steam may be diffused around the liquid in the interval between the wooden vessel and an interior metallic case. The second mode is of universal applicability. Since a gallon of water in the form of steam will heat 6 gallons at 50, up to the boiling point, or 162; 1 gallon of the former will be adequate to heat 18 gallons of the latter up to 100, making a liberal allowance for waste in the conducting pipe. Cooking of food for man and cattle is like- wise another useful application of steam ; " for," says Dr. Black, " it is the most effec- tual carrier of heat that can be conceived, and will deposit it only on such bodies as are colder than boiling water." Hence in a range of pots, whenever the first has reached the boil- ing point, but no sooner, the steam will go onwards to the second, then to the third, and thus in succession. Inspection of the last will therefore satisfy us of the condition of ths preceding vessels. Distillation has been lately practised, by surrounding the still with a strong metallic case, and filling the interstice with steam heated up to 260* or 280. But notwithstanding of safety valves, and every ordinary attention, dangerous ex- plosions have happened. Distillation in vacuo, by the heat of external steam of ordinary strength, would be a safe and elegant process. The old, and probably very exact experiments of Mr. Watt on this subject, do not lead us, however, to expect any saving of fuel, merely by the vacuum distillation. " The unex- pected result of these experiments is, that there is no advantage to be expected in the manufacture of ardent spirits by distillation in vacua. For we find, that the latent heat of the steam is at least as much increased as the sensible heat is diminished." Dr. Black's Lectures, vol. i. p. 190. By advantage is evidently meant saving of fuel. But in preparing spirits, ethers, vine- gars, and essential oils, there would undoubt- edly be a great advantage relative to flavour. Every risk of empyreuma is removed. Chambers filled with steam heated to about 125 Fahr. have been introduced with advan- tage into medicine, under the name of vapour baths. Dry air has also been used. It can be tolerated at a much greater heat than moist air; see TEMPERATURE. A large cradle, containing saw-dust heated with steam, should be kept in readiness at the houses erected by the Humane Society for the recovery of drowned persons ; or a steam chamber might be attached to them for this purpose, as well as general medicinal uses. I have thus completed what I conceive to belong directly to caloric in a chemical dic- tionary. Under alcohol, attraction, blowpipe, climate, combustion, congelation, digester, dis- tillation, electricity, g^s, light, pyrometer, thermometer, water, some interesting correla- tive facts will be found. CALORIMETER. An instrument con* trived by Lavoisier and Laplace, to measure the heat given out by a body in cooling, from the quantity of ice it melts. It consists of three vessels, one placed within the other, so as to leave two cavities between them ; and a frame of iron network, to be suspended in the middle of the inner vessel. This network is to hold the heated body. The two exterior concentric interstices are filled with bruised ice. The outermost serves to screen from the atmosphere the ice in the middle space, by the fusion of which the heat given out by the central hot body is measured. The water runs off through the bottom, which terminates in the shape of a funnel, with a stop-cock. CALP. An argillo-ferruginous limestone. CAMELEON MINERAL. When pure potash and black oxide of manganese are fused together in a crucible, a compound is formed, CAM 288 CAM Whose solution in water, at first green, passes spontaneously through the whole series of co- loured rays to the red. From this latter tint, the solution may be made to retrograde in colour to the original green, by the addition of potash ; or it may be rendered altogether colourless, by adding either sulphurous acid or chlorine to the solution, in which case there may or may not be a precipitate, according to circumstances. MM. Chevillot and Edouard have lately read some interesting memoirs on this substance, before the Academy of Sciences. They found, that when potash and the green oxide of manganese were heated in close ves- sels, containing azote, no cameleon is formed. The same result followed with the brown ox- ide, and ultimately with the black. They therefore ascribe the phenomena to the absorp- tion of oxygen, which is greatest when the oxide of manganese equals the potash in weight. They regard it as a manganesiate of potash, though they have hitherto failed in their attempts to separate this supposed te- troxide, or manganesic acid. When acids are poured upon the green cameleon, or an alkali upon the red, they are equally changed from one colour to the other; even boiling and agitation are sufficient to disengage the excess of potash in the green cameleon, and to change it into red. Many acids also, when used in excess, decompose the cameleon entirely, by taking the potash from it, disengaging the oxygen, and precipitating the manganese in the state of black oxide. Sugar, gums, and several other substances, capable of taking away the oxygen, also decompose the came- leon, and an exposure to the air likewise pro- duces the same effect. Soda, barytes, and strontites, also afford peculiar cameleons. The red potash cameleon is perfectly neutral. Phosphorus brought in contact with it, pro- duces a detonation ; and it sets some other combustibles on fire. Exposed alone to heat, it is resolved into oxygen, black oxide of man- ganese, and green cameleon, or submangane- siate of potash. CAMPEACHY WOOD. See LOG- WOOD. CAMPHOR. There are two kinds grow in the East, the one produced in the islands of Sumatra and Borneo, and the other pro- duced in Japan and China. Camphor is extracted from the roots, wood, and leaves of two species of laurus, the roots affording by far the greatest abundance. The method consists in distilling with water in large iron pots, serving as the body of a still, with earthen heads adapted, stuffed with straw, and provided with receivers. Most of the camphor becomes condensed in the solid form among the straw, and part comes over with the water. The sublimation of camphor is performed in low flat-bottomed glass vessels placed in sand ; and the camphor becomes concrete in a pure state against the upper part, whence it it afterwards separated with a knife, after break- ing the glass. Lewis asserts, that no addition is requisite in the purification of camphor; but that the chief point consists in managing the fire, so that the upper part of the vessel may be hot enough to bake the sublimate together into a kind of cake. Chaptal says, the Hollanders mix an ounce of quicklime with every pound of camphor previous to the distillation. Purified camphor is a white concrete crys- talline substance, not brittle, but easily crum- bled, having a peculiar consistence resembling that of spermaceti, but harder. It has a strong lively smell, and an acrid taste ; is so volatile as totally to exhale when left exposed in a warm air ; is light enough to swim on water ; and is very inflammable, burning with a very white flame and smoke, without any resi- due. The roots of zedoary, thyme, rosemary, sage, the inula hellenium, the anemony, the pasque flower or pulsatilla, and other vege- tables, afford camphor by distillation. It is observable, that all these plants afford a much larger quantity of camphor, when the sap has been suffered to pass to the concrete state by several months' drying. Thyme and pepper- mint, slowly dried, afford much camphor ; and Mr. Achard has observed, that a smell of camphor is disengaged when volatile oil of fennel is treated with acids. Mr. Kind, a German chemist, endeavouring to incorporate muriatic acid gas with oil of turpentine, by putting this oil into the vessels in which the gas was received when extricated, found the oil change first yellow, then brown, and lastly, to be almost wholly coagulated into a crystalline mass, which comported itself in every respect like camphor. Troms- dorff and Boullay confirm this. A small quantity of camphor may be obtained from oil of turpentine by simple distillation at a very gentle heat. Other essential oils, how- ever, afford more. By evaporation in shallow vessels, at a heat not exceeding 57- F., Mr. Proust obtained from oil of lavender .25, of sage .21, of marjoram .1014. of rosemary .0625. He conducted the operation on a pretty large scale. Camphor is not soluble in water in any perceptible degree, though it communicates its smell to that fluid, and may be burned as it floats on its surface. It is said, however, that a surgeon at Madrid has effected its solu- tion in water by means of the carbonic acid. Camphor may be powdered by moistening it with alcohol, and triturating it till dry. It may be formed into an emulsion by previous grinding with near three times its weight of almonds, and afterwards gradually adding the water. Yolk of egg and mucilages are also effectual for this purpose ; but sugar does not answer wclL CAM 289 CAN It has been observed by Romieu, that small pieces of camphor floating on water have a rotatory motion. Alcohol, ethers, and oils, dissolve cam- phor. The addition of water to the spirituous or acid solutions of camphor, instantly sepa- rates it. Mr. Hatchett has particularly examined the action of sulphuric acid on camphor. A hundred grains of camphor were digested in an ounce of concentrated sulphuric acid for two days. A gentle heat was then applied, and the digestion continued for two days longer. Six ounces of water were then added, and the whole distilled to dryness. Three grains of an essential oil, having a mixed odour of lavender and peppermint, came over with the water. The residuum being treated twice with two ounces of alcohol each time, fifty-three grains of a compact coal in small fragments remained undissolved. The alcohol, being evaporated in a water bath, yielded forty-nine grains of a blackish-brown sub- stance, which was bitter, astringent, had the smell of caromel, and formed a dark brown solution with water. This solution threw down very dark brown precipitates, with sul- phate of iron, acetate of lead, muriate of tin, and nitrate of lime. It precipitated gold in the metallic state. Isinglass threw down the whole of what was dissolved in a nearly black precipitate. When nitric acid is distilled repeatedly in large quantities from camphor, it converts it into a peculiar acid. See ACID (CAMPHO- RIC). Camphor melts at 288, and boils at the temperature of 400. By my analysis cam- phor is composed, in 100 parts, of 77-38 car- bon, 11.14 hydrogen, and 11.48 oxygen. It is therefore nearly represented by Carbon Hydrogen Oxygen 10 atoms 7-5 9 1.125 1 1. 78.02 11.58 1040 9.G25 100.00 or, 9 atoms olefiant gas -J- 1 atom carbonic acid. As an internal medicine, camphor has been frequently employed in doses from 5 to 20 grams, with much advantage, to procure sleep in mania, and to counteract gangrene. Though a manifest stimulant, when externally applied, it appears from the reports of Cullen and others, rather to diminish the animal tempera- ture and the frequency of the pulse. In large doses it acts as a poison, an effect best coun- teracted by opium. It is administered to al- leviate the irritating effects of cantharides, mezereon, the saline preparations of mercury and drastic purgatives. It lessens the nau- seating tendency of squill, and prevents it from irritating the bladder. It is employed externally as a discutient. Its effluvia are very offensive to insects, on which account it is much used to defend subjects of natural history from their ravages. CANCER (MATTER OF). This mor- bid secretion was found by Dr. Crawford to give a green colour to syrup of violets, and, treated with sulphuric acid, to emit a gas re- sembling sulphuretted hydrogen, which he sup- poses to have existed in combination with am- monia in the ulcer. Hence the action of viru- lent pus on metallic salts. He likewise ob- served, that its odour was destroyed by aque- ous chlorine, which he therefore recommends for washing cancerous sores. CANDLES. Cylinders of tallow or wax, containing in their axis a spongy cord of cot- ton or hemp. A few years ago I made a set of experiments on the relative intensities of light, and duration of different candles, the re* suit of which is contained in the following table* Number in a Pound. Duration of a Candle. Weight in grains. Consumption per hour, grains. Proportion of light. Economycf Light. Candles equal one argand. 10 mould, 5 h. 9m. 682 132 12* 68 5.7 10 dipped, 8 mould, 4 36 6 31 672 856 150 132 13 10 59| 5.25 6.6 6 do. 7 2| 1160 163 14 66 5.0 4 do. 9 36 1787 186 20^ 80 3.5 Argand oil flame. 512 69.4 100 A Scotch mutchkin or 1- 8th of a gallon of good seal oil, weighs 6010 gr. or 13 and 1-lOthoz. avoirdupois, and lasts in a bright argand lamp 11 hours 44 minutes. The weight of oil it consumes per hour is equal to four times the weight of tallow in candles 8 to the pound, and 3 f times the weight of tallow in candles 6 to the pound. But its light be- ing equal to that of 5 of the latter candles, it appears from the above table, that 2 pounds weight of oil, value 9d. in an argand, are equi- valent in illuminating power to 3 pounds of CAN 290 CAO tallow candles, which cost about two shillings. The larger the flame in the above candles, the greater the economy of light. CANNEL COAL. See COAL. CANNON METAL. See CorrEn. CANTHARIDES. Insects vulgarly called Spanish flies : lytta vesicatoria is the name adopted from Gmelin, by the London college. This insect is two-thirds of an inch in length, one-fourth in breadth, oblong, and of a gold shining colour, with soft elytera or wing sheaths, marked with three longitudinal raised stripes, and covering brown membranous wings. An insect of a square form, with black feet, but possessed of no vesicating property, is sometimes mixed with the cantharides. They have a heavy disagreeable odour, and acrid taste. If the inspissated watery decoction of these insects be treated with pure alcohol, a solution of a resinous matter is obtained, which being separated by gentle evaporation to dryness, and submitted for some time to the action of sul- phuric ether, forms a yellow solution. By spontaneous evaporation, crystalline plates are deposited, which may be freed from some ad- hering colouring matter by alcohol. Their appearance is like spermaceti. They are so- luble in boiling alcohol, but precipitate as it cccls. They do not dissolve in water. Accord- ing to M. Robiquet, who first discovered them, these plates form the true blistering principle. They might be called VESICATORIN. Be- sides the above peculiar body, cantharides contain, according to M. Robiquet, a green bland oil, insoluble in water, soluble in alco- hol ; a black matter, soluble in water, insolu- ble in alcohol, without blistering properties ; a yellow viscid matter, mild, soluble in water and alcohol ; the crystalline plates ; a fatty bland matter ; phosphates of lime and mag- nesia ; a little acetic acid, and much lithic or uric acid. The blistering fly taken into the stomach in doses of a few grains, acts as a poi- son, occasioning horrible satyriasis, delirium, convulsions, and death. Some frightful cases are related by Orfila, vol. i. part 2d. Oils, milk, syrups, frictions on the spine, with vo- latile liniment and laudanum, and draughts containing musk, opium, and camphoretted emulsion, are the best antidotes. Cantharides consist, by my analysis, of 48.64 carbon + 5.09 hydrogen + 36.29 oxy- gen + 9-08 a~ote = 100. Their constitution approximates to Carbon 11 atoms Hydrogen 10 Oxygen 7 Azote 1 19.75 100.0 CAOUTCHOUC. This substance, which has been improperly termed elastic gum^ and vulgarly, from its common application to rub out pencil marks on paper, India rubber, is obtained from the milky juice of different plants in hot countries. The chief of these are the Jutroplia elastlca^ and Urceola elas- tica. The juice is applied hi successive coatings on a mould of clay, and dried by the fire or in the sun ; and when of a sufficient thickness, the mould is crushed, and the pieces shaken out. Acids separate the caoutchouc from the thinner part of the juice at once by coagulating it. The juice of old plants yields nearly two- thirds of its weight ; that of younger plants less. Its colour, when fresh, is yellowish-white, but it grows darker by exposure to the air. The elasticity of this substance is its most remarkable property : when warmed, as by immersion in hot water, slips of it may be drawn out to seven or eight times their ori- ginal length, and will return to their former di- mensions nearly. Cold renders it stiffand rigid, but warmth restores its original elasticity. Exposed to the fire it softens, swells up, and burns with a bright flame. In Cayenne it is used to give light as a candle. Its solvents are ether, volatile oils, and petroleum. The ether, however, requires to be washed with water re- peatedly, and in this state it dissolves it com- pletely. Pelletier recommends to boil the ca- outchouc in water for an hour ; then to cut it into slender threads ; to boil it again about an hour ; and then to put it into rectified sulphu- ric ether in a vessel close stopped. In this way he says it will be totally dissolved in a few days, without heat, except the impurities, which will fall to the bottom if ether enough be em- ployed. Berniard says, the nitrous ether dis- solves it better than the sulphuric. If this so- lution be spread on any substance, the ether evaporates very quickly, and leaves a coating of caoutchouc unaltered in its properties. Naphtha, or petroleum, rectified into a colour- less liquid, dissolves it, and likewise leaves it unchanged by evaporation. Oil of turpentine softens it, and forms a pasty mass, that may be spread as a varnish, but is very long in dry- ing. A solution of caoutchouc in five times its weight of oil of turpentine, and this solution dissolved in eight times its weight of drying linseed oil by boiling, is said to form the var- nish of air-balloons. Alkalis act upon it so as in time to destroy its elasticity. Sulphuric acid is decomposed by it ; sulphurous acid be- ing evolved, and the caoutchouc converted into charcoal. Nitric acid acts upon it with heat ; nitrous gas being given out, and oxalic acid crystallizing from the residuum. On distilla- tion it gives out ammonia, and carburetted hy- drogen. By my analysis, Caoutchouc is composed in 1QO parts of 90.00 carbon, 9.11 hydrogen, and 0.88 oxygen. It probably consists there- fore of CAO 291 CAR Carbon 3 atoms Hydrogen 2 2.25 0.25 !M 10 " . 2.50 100 or it is a sesqui-carburetted hydrogen. The oxygen deduced from experiment is in such small quantity, as to leave a doubt whether it be essential to this body, or imbibed in minute quantity from the atmosphere during its con- solidation. Mr. Faraday has lately written an ingeni- ous memoir on Caoutchouc. He obtained it from Mexico in the fluid state, nearly as it exudes from the tree. The only alteration was a slight film of solid caoutchouc on the surface of the cork which closed the bottle. The fluid was a pale-yellow, thick, cream- looking substance, of uniform consistency. It had a disagreeable acescent odour, something resembling that of putrescent milk ; its sp. gr. was 1.01174. When exposed to the air in thin films it soon dried, losing weight, and leaving caoutchouc of the usual appearance and colour ; and very tough and elastic. 202.4 gr. of the liquid dried in a Wedgewood basin, at 100 F., became in a few days 94.4 grains, and the solid piece formed being then removed from the capsule, and exposed on all sides to the air until quite dry, became 01 grains. Hence 100 parts of juice left nearly 45 of solid matter. Heat immediately coagulates the juice, the caoutchouc separating in its solid form from the aqueous matter. Alcohol has a similar effect. The juice mixes freely with water, but after some time a creamy portion rises to the top, while a clear watery solution of the matters associated with caoutchouc in the juice remains below. In this way liquid caoutchouc may be purified by washing. When this is thrown on a filter, the water passes through and leaves coagulated caout- chouc. This pure transparent substance has when dry a sp. gravity of 0.925. It is a non- conductor of electricity. It is not dissolved when boiled in solution of potash. " It yields no ammonia by destructive distillation, nor any compounds of oxygen, and my experi- ments agree with those of Dr. Ure, in indi- cating carbon and hydrogen as its only ele- ments. I have not however been able to verify his proportions, which are 90 carbon, 9-11 hydrogen, or by theory nearly 3 pro- portionals of carbon to 2 of hydrogen, and have never obtained quite so much as 7 carbon to I hydrogen by weight." This difference in Mr. Faraday's results, I would ascribe to a difference in the nature of the caoutchouc; I for it is certain that by my mode of ultimate : analysis I can never have an error of carbon in excess. Mr. Faraday's mean results are 8 ; atoms of -carbon -(- 1 of hydrogen, nearly. i Journal of Science, xxi. 19. Caoutchouc may be formed into various ar- ticles without undergoing the process of solu- tion. If it be cut into an uniform slip of a pro- per thickness, and wound spirally round a glass or metal rod, so that the edges shall be in close contact, and in this state be boiled for some time, the edges will adhere so as to form a tube. Pieces of it may be readily joined by touching the edges with the solution in ether ; but this is not absolutely necessary, for, if they be mere- ly softened by heat, and then pressed together, they will unite very firmly. If linseed oil be rendered very drying by digesting it upon an oxide of lead, and after- ward applied with a small brush on any sur- face, and dried by the sun or in the smoke, it will afford a pellicle of considerable firmness, transparent, burning like caoutchouc, and wonderfully elastic. A pound of this oil, spread upon a stone, and exposed to the air for six or seven months, acquired almost all the properties of caoutchouc : it was used to make catheters and bougies, to varnish bal- loons, and for other purposes. Of the mineral caoutchouc there are several varieties : 1. Of a blackish-brown inclining to olive, soft, exceedingly compressible, unctuous, with a slightly aromatic smell. It burns with a bright flame, leaving a black oily residuum, which does not become dry. 2. Black, dry, and cracked on the surface, but, when cut into, of a yellowish-white. A fluid resem- bling pyrolignic acid exudes from it when recently cut. It is pellucid on the edges, and nearly of a hyacinthine red colour. 3. Simi- lar to the preceding, but of a somewhat firmer texture, and ligneous appearance, from having acquired consistency in repeated layers. 4. Resembling the first variety, but of a darker colour, and adhering to grey calcareous spar, with some grains of galasna. 5. Of a liver- brown colour, having the aspect of the vege- table caoutchouc, but passing by gradual transition into a brittle bitumen, of vitreous lustre, and a yellowish colour. 6. Dull red- dish-brown, of a spongy or cork-like texture, containing blackish-grey nuclei of impure caoutchouc. Many more varieties are enu- merated. One specimen of this caoutchouc has been found in a petrified marine shell enclosed in a rock, and another enclosed in crystallized fluor spar. The mineral caoutchouc resists the action of solvents still more than the vegetable. The rectified oil of petroleum affects it most, par- ticularly when by partial burning it is resolved into a pitchy viscous substance. A hundred grains of a specimen analyzed in the dry way by Klaproth afforded carburetted hydrogen gas 38 cubic inches, carbonic acid gas 4, bitu- minous oil 73 grains, acidulous phlegm 1.5, charcoal 6.25, lime 2, silex 1.5, oxide of iron .75, sulphate of lime .5, alumina .25. CAPUT MORTUUM. The inert resi- duum of a distillation, or sublimation. The term is nearly obsolete. CARAT. See ASSAV and DIAMOND. u2 CAR 292 CAR CARBON. When vegetable matter, par- ticularly the more solid, as wood, is exposed to heat in close vessels, the volatile parts fly off, and leave behind a black porous substance, which is charcoal. If this be suffered to un- dergo combustion in contact with oxygen, or with atmospheric air, much the greater part of it will combine with the oxygen, and escape in the form of gas ; leaving about a two-hun- dredth part, which consists chiefly of different saline and metallic substances. This pure inflammable part of the charcoal is what is commonly called carbon: and if the gas be received into proper vessels, the carbon will be found to have been converted by the oxy- gen into an acid, called the carbonic. See ACID (CARBONIC). From the circumstance that inflammable substances refract light in a ratio greater than that of their densities, Newton inferred that the diamond was inflammable. The quantity of the inflammable part of charcoal requisite to form a hundred parts of carbonic acid, was calculated by Lavoisier to be twenty- eight parts. From a careful experiment of Mr. Tennant, 27-6 parts of diamond, and 72.4 of oxygen, formed 100 of carbonic acid ; and hence he inferred the identity of diamond and the inflammable part of chaicoal. Diamonds had been frequently consumed in the open air with burning-glasses ; but Lavoisier first consumed them in oxygen gas, and discovered carbonic acid to be the only result. Sir George Mackenzie showed, that a red heat, inferior to what melts silver, is suf- ficient to burn diamonds. They first enlarge somewhat in volume, and then waste with a feeble flame. M. Guyton Mctveau was the first who dropped diamonds into melted nitre, and observed the formation of carbonic acid. From a number of experiments which M. Biot has made on the refraction of different substances, he has been led to form a different opinion. According to him, if the elements of which a substance is composed be known, their proportions may be calculated with the greatest accuracy from their refractive powers. Thus he finds, that the diamond cannot be pure carbon, but requires at least one-fourth of hydrogen, which has the greatest refractive power of any substance, to make its refraction commensurate to its density. In 1809, Messrs. Allen and Pepys made some accurate researches on the combustion of various species of carbon in oxygen, by means of an elegant apparatus of their own con- trivance. A platina tube traversing a fur- nace, and containing a given weight of the carbonaceous substance, was connected at the ends with two mercurial gasometers, one of which was filled with oxygen gas, and the other was empty. The same weight of dia- mond, carbon, and plumbago, yielded very nearly the same volume of carbonic acid. Sir H. Davy was the first to show that the diamond was capable of supporting its own combustion in oxygen, without the continued application of extraneous heat ; and he thus obviated one of the apparent anomalies of this body, com- pared with charcoal. This phenomenon, by his method, can now be easily exhibited. If the diamond, supported in a perforated cup, be fixed at the end of a jet, so that a stream of hydrogen can be thrown on it, it is easy, by inflaming the jet, to ignite the gem, and whilst in that state to introduce it into a globe or flask containing oxygen. On turning off the hydro- gen, the diamond enters into combustion, and will go on burning till nearly consumed. The loss of weight, and corresponding production of carbonic acid, were thus beautifully shown. A neat form of apparatus for this purpose, is delineated by Mr. Faraday, in the 9th volume of the Journal of Science. Sir H . Davy found, that diamonds gave a volume of pure carbonic acid, equal to the oxygen consumed ; charcoal and plumbago afforded a minute portion of hydrogen. See DIAMOND. Well -burned charcoal is a conductor of electricity, though wood simply deprived of its moisture by baking is a non-conductor ; but it is a very bad conductor of caloric, a property of considerable use on many occasions, as in lining crucibles. It is insoluble in water, and hence the utility of charring the surface of wood exposed to that liquid, in order to preserve it, a circumstance not unknown to the ancients. This prepara- tion of timber has been proposed as an effec- tual preventive of what is commonly called the dry-rot. It has an attraction, however, for a certain portion of water, which it retains very forcibly. Heated red-hot, or nearly so, it de- composes water ; forming with its oxygen car- bonic acid, or carbonic oxide, according to the quantity present ; and with the hydrogen a gaseous carburet, called carburetted hydrogen, or heavy inflammable air. Charcoal is infusible by any heat. If ex- posed to a very high temperature in close ves- sels, it loses little or nothing of its weight, but shrinks, becomes more compact, and acquires a deeper black colour. Recently prepared charcoal has a remarkable property of absorbing different gases, and con- densing them in its pores without any alter- ation of their properties or its own. The following are the latest results of M. Theodore de Saussure with boxwood charcoal, the most powerful species : Gaseous ammonia, Ditto muriatic acid, Ditto sulphurous acid, Sulphuretted hydrogen, Nitrous oxide, Carbonic oxide, Olefiant gas, Carbonic oxide, Oxygen, 90 vols. 85 65 55 40 35 35 942 9-25 CAR 293 CAK Azote, 7-5vols. Light gas from moist charcoal, 50 Hydrogen, 1-75 Very light charcoal, such as that of cork, absorbs scarcely any air; while the pit-coal of Rastiberg, sp. gr. 1-326, absorbs 10 times its volume. The absorption was always com- pleted in 24 hours. This curious faculty, which is common to all porous bodies, resem- bles the action of capillary tubes on liquids. When a piece of charcoal, charged with one gas, is transferred into another, it absorbs some of it, and parts with a portion of that first con- densed. In the experiments of Messrs. Allen and Pepys, charcoal was found to imbibe from the atmosphere in a day about l-8th of its weight of water. For a general view of ab- sorption, see GAS. When oxygen is condensed by charcoal, carbonic acid is observed to form at the end of several months. But the most remarkable property displayed by charcoals impregnated with gas, is that with sulphuretted hydrogen, when exposed to the air or oxygen gas. The sulphuretted hydrogen is speedily destroyed, and water and sulphur result, with the disen- gagement of considerable heat. Hydrogen alone has no such effects. When charcoal was exposed by Sir H. Davy to intense ignition in vacua, and in condensed azote, by means of Mr. Children's magnificent voltaic battery, it slowly volatilized, and gave out a little hydro- gen. The remaining part was always much harder than before ; and in one case so hard as to scratch glass, while its lustre was increased. This fine experiment may be regarded as a near approach to the production of diamond. Charcoal has a powerful affinity for oxygen, whence its use in disoxygenating metallic oxides, and restoring their base to its original metallic state, or reviving the metal. Thus too it decomposes several of the acids, as the phosphoric and sulphuric, from which it ab- stracts their oxygen, and leaves the phosphorus and sulphur free. Carbon is capable of combining with sul- phur, and with hydrogen. With iron it forms steel ; and it unites with copper into a car- buret, as observed by Dr. Priestley. A singular and important property of char- coal is that of destroying the smell, colour, and taste of various substances : for the first accurate experiments on which we are chiefly indebted to Mr. Lowitz of Petersburgh, though it had been long before recommended to cor- rect the fetor of foul ulcers, and as an anti- septic. On this account it is certainly the best dentifrice. Water that has become putrid by long keeping in wooden casks, is rendered sweet by filtering through charcoal powder, or by agitation with it : particularly if a few drops of sulphuric acid be added. Common vinegar boiled with charcoal powder becomes perfectly limpid. Saline solutions, that are tinged yel- low or brown, are rendered colourless in the same way, so as to afford perfectly white cry- stals. The impure carbonate of ammonia ob- tained from bones, is deprived both of its colour and fetid smell by sublimation with an equal weight of charcoal powder. Malt spirit is freed from its disagreeable flavour by distil- lation from charcoal ; but if too much be used, part of the spirit is decomposed. Simple maceration, for eight or ten days, in the pro- portion of about 1 -1 50th of the weight of the spirit, improves the flavour much. It is neces- sary that the charcoal be well burned, brought to a red heat before it is used, and used as soon as may be, or at least be carefully excluded from the air. The proper proportion too should be ascertained by experiment on a small scale. The charcoal may be used repeatedly, by exposing it for some time to a red heat be- fore it is again employed. Charcoal is used on particular occasions as fuel, on account of its giving a strong and steady heat without smoke. It is employed to convert iron into steel by cementation. It enters into the composition of gunpowder. In its finer states, as in ivory black, lamp black, &c. it forms the basis of black paints, Indian ink, and printers' ink. The purest carbon for chemical purposes is obtained by strongly igniting lamp black in a t covered crucible. This yields, like the dia- mond, unmixed carbonic acid by combustion in oxygen. Carbon unites with all the common simple combustibles, and with azote, forming.a series of most important compounds. With sulphur it forms a curious limpid liquid called carburet of sulphur, or sulphuret of carbon. With phosphorus 1 it forms a species of compound, whose properties are imperfectly ascertained. It unites with hydrogen in two definite propor- tions, constituting subcarburetted and carbu- ' retted hydrogen gases. With azote it forms prussic gas, the cyanogen of M. Gay Lussac. Steel and plumbago are two different com- pounds of carbon with iron. In black chalk we find this combustible intimately associated with silica and alumina. The primitive com- bining proportion, or prime equivalent of car- bon, is 0.75 on the oxygen scale. CARBON (MINERAL), is of a greyish- black colour. It is charcoal, with various pro- portions of earth and iron, without bitumen. It has a silky lustre, and the fibrous texture of wood. It is found in small quantities, stratified with brown coal, slate coal, and pitch coal. CARBON (Chlorides of). For the know- ledge of this interesting class of compounds, we are indebted to Mr. Faraday. If chlorine and olefiant gas be mixed in equal volumes, they are condensed into an oily looking liquid, sometimes called chloric ether. (See CARBURETTED HYDROGEN.) If some of this be put into a retort with chlorine, it CAR 294 CAR becomes yellow ; but on exposure to the sun- beams, heat is produced, and the colour of the gas and liquid disappears in a few seconds. On opening the retort under mercury, there is no absorption. It is found to be now full of muriatic acid gas. If we expel this, introduce more chlorine, and again expose to the sun light, the colour which had been regenerated again disappears, while a few moist crystals form round the edge of the fluid. Chlorine being a third time introduced, and subjected to the same influence, more hydrogen is with- drawn from the liquid, and a crystalline sub- limate lines the retort. By proceeding in this way, till the chlorine exerts no farther action, the fluid entirely vanishes, and leaves in its stead the crystalline matter and muriatic acid. Mr. Faraday Bext added at once to a por- tion of olefiant gas eight or nine times its bulk of chlorine, and exposed the mixture to sunshine. At first the fluid formed ; but it speedily disappeared ; the retort became lined with crystals, and the colour of the chlorine grew paler. These crystals are a chloride of carbon. As water does not interfere with the action of the substances, Mr. Faraday admitted a little of it, which condensed the muriatic acid gas, and allowed a new volume of chlorine to be introduced into the retort to de-hydrogenate the chloric ether, by the aid of light. In order to insulate the substance, the residuary chlo- rine and muriatic acid gas were blown out of the vessel with a pair of bellows ; and the con- densed muriatic acid gas, and other soluble matters, were washed away with water. The crystalline substance is to be now washed from the retort into another jar. A little alcohol will remove the last adhering portions. This being poured into the water, wilL throw down the chloride to the bottom of the vessel. It ought to be next dried by pressure between the folds of porous paper. It is then to be sublimed in a glass tube, by the heat of a spirit lamp. The pure substance will rise first along with a little water ; but the last portions will be partially decom posed, muriatic acid being evolved, while charcoal remains. The sublimed matter is to be dissolved in alcohol, and the solution is to be poured into a weak potash ley, by which the chloride is thrown down, and the muriatic acid neutralized and separated. Water will now wash away the muriatic acid and muriate, leaving the sub- stance pure. Collect it on a filter, and dry it, first between the folds of blotting paper, and lastly, over sulphuric acid, in the exhausted receiver. It will now appear as a white pulverulent substance; and, if perfectly pure, will not afford the slightest trace of carbon, or muriatic acid, when sublimed in a tube. Its solution in ether should not affect solution of nitrate of silver. If it does, it must be resublimed, washed, and dried. For the formation of this substance, the direct rays of the sun are not absolutely neces* sary. The light of day, acting for a few hours, will determine its production. It will form even in the dark, at the end of a few days. The solid thus obtained is the perchloride. It is transparent and colourless. Jt has scarcely any taste. Its odour is aromatic, approaching to that of camphor. Its specific gravity is as nearly as possible 2. In refractive power, it equals flint glass (1.5767). It is very fusible, easily breaking down under pressure; and, when scratched, has much of the feel and ap- pearance of white sugar. It does not conduct electricity. The crystals obtained by sublimation, as well as from solutions of the substance in alco- hol and ether, are dendritical, prismatic, or in plates. The varieties of form, which are very interesting, are easily ascertained, and result from a primitive octohedron. It volatilizes slowly at common tempera- tures, and passes, in the manner of camphor, towards the light. If heated, it rises more rapidly, forming fine crystals. When the temperature is raised to 320 F. it fuses ; and to 360 it boils. When condensed from these rapid sublimations, it forms a transparent and scarcely visible crust; which, soon after it cools, becomes white and nearly opaque. If the heat be raised still higher, as when the substance is passed through a red-hot tube, it is decomposed, chlorine is evolved, and another chloride of carbon, which condenses into a liquid, is obtained. This shall be described presently. It is not readily combustible. When held in the flame of a spirit lamp, it burns with a red flame, emitting much smoke and acid fumes ; but on removal from the lamp, its combustion ceases. When it is heated to red- ness in pure oxygen, it sometimes burns with a brilliant light. It is insoluble in water, but soluble in al- cohol, and copiously with the aid of heat It is still more soluble in ether. The hot ethere- ous solution deposits, on cooling, very beauti- ful crystals. It is soluble also in the volatile oils ; from which it may be obtained in crys- tals by evaporation. Fixed oils likewise dis- solve it. Solutions of the acids and alkalis do not act with any energy on this chloride. When oxygen, mixed with its vapour, is passed through a red-hot tube, there is de- composition ; and mixtures of chlorine, car- bonic oxide, carbonic acid, and phosgene gases are obtained. Chlorine produces no change on this sub- stance. When iodine is heated with it at moderate temperatures, the two substances unite with fusion, and there is no further ac- tion. When heated more strongly in vapour of iodine, the iodine separates chlorine, re- ducing the perchloride to the fluid protochlo- ride of carbon, while chloriodine is formed- CAR CAR This dissolves, and if no excess of iodine be present, the whole remains fluid at common temperatures. When water is added, it gene- rally liberates a little iodine ; and on heating the solution so as to expel all free iodine, and testing by nitrate of silver, chloride and iodide of silver are obtained. When a mixture of hydrogen and vapour of the perchloride is transmitted through a red-hot tube, the latter is decomposed with the production of muriatic acid gas and char- coal. Sulphur and phosphorus unite to it by fusion. If phosphorus be heated in the vapour of this chloride, it abstracts chlorine, whence result protochloride of phosphorus and carbon. If heated more highly, it inflames. Most of the metals decompose it at high temperatures. Potassium burns brilliantly in the vapour ; when a chloride of potassium is formed, and charcoal deposited. Iron, zinc, tin, copper, and mercury, act on it at a red heat, forming chlorides of these metals, with deposition of the charcoal. The peroxides of mercury, copper, lead, and tin, heated with the perchloride, produce chlorides of the re- spective metals and carbonic acid; and the protoxides of zinc, lead, &c. produce also chlo- rides ; but the gaseous product is a mixture of carbonic acid and carbonic oxide. Phosgene gas is occasionally formed on passing the perchloride over heated oxide of zinc. When the vapour of the chloride is passed over red-hot lime, barytes, or strontites, a very vivid combustion is produced. The oxygen and the chlorine change places. The com- bustion is due to the formation of the earthy chlorides, and carbonic acid ; the last being absorbed by the undecomposed portions of the earths. Carbon is also deposited. No car- bonic oxide is obtained. When the substance is passed over ignited magnesia, there is no action on the earth ; but the perchloride of car- bon is converted by the heat into a protochlo- ride. In these experiments with ihs oxides, no trace of water could be perceived. The most perfect demonstration of the new body containing no hydrogen, is evident from this, that when the fluid compound of chlorine and olefiant gas is acted on by chlorine and the sunbeams in close vessels, there is no change of volume, though the whole of the chlorine dis- appears ; its place being occupied by muriatic acid gas. Hence, as muriatic acid gas is known to consist of equal volumes of chlorine and hydrogen, combined without change of bulk, it is evident that half of the chlorine intro- duced into the vessel is fixed in the elements of the liquid, and has liberated an equal volume of hydrogen ; and as, when the chlo- ride is perfectly formed, it condenses no mu- riatic acid gas, a method, apparently free from all fallacy, is thus afforded of ascertaining its nature. By a train of well -conducted experiments, Mr. Faraday ascertained, that 1 volume of olefiant gas requires 5 volumes of chlorine for its conversion into muriatic acid and chloride of carbon ; that 4 volumes of muriatic acid gas are formed ; that 3 volumes of chlorine combine with the 2 volumes of carbon in the olefiant gas to form the solid crystalline chlo- ride ; and that when chlorine acts on the fluid compound of chlorine and olefiant gas, for every volume of chlorine that combines, an equal volume of hydrogen is separated. He verified these proportions by analysis, transmitting the substance in vapour slowly over metals and metallic oxides, (chiefly per- oxide of copper.) The composition of the perchloride of car- bon is, 3 prime proportions of chlorine, 2 carbon. Mr. Faraday's numbers are 100.5 -f 1 1.4. According to the numbers adopted in this work, thay are 13.5 + 1.5, or in 100 parts, 90 chlorine + 10 carbon. 2. Protochloride of carbon. By heating some of the perchloride in a glass tube, over a spirit lamp, the substance at first sublimes ; but as the vapour becomes heated below, it is gradually converted into protochloride, while chlorine is disengaged. To obtain it pure, he passes some of the perchloride to the sealed end of a tube, and fifis the space above it for 10 or 12 inches with fragments of rock-crys- tal. The part of the tube beyond this is bent zigzag 2 or 3 times, so that the angles may form receivers for the new bodv. These angles being plunged in cool water, he heats the tube and rock-crystal to bright redness; after which the perchloride is slowly sublimed by a spirit lamp ; and on passing into the hot part of the tube is decomposed. A fluid passes over, which is condensed in the angles of the tube, and chlorine is separated ; part of the gas escapes, but the greater portion is retained in solution by the fluid, and renders it yellow. Having proceeded thus far, we may then separate the bent portion of the tube from that within the furnace, by the skilful use of the blowpipe, which will seal the end of the tube. This now forms a retort ; in which we may chase the fluid by heat, from one end to another, four or five times ; whereby the excess of chlorine will be expelled, and the chloride obtained limpid and colourless. The small proportion of perchloride which still remains, is separable by another distilla- tion in vacuo, at a heat little above that of the atmosphere ; the protochloride being the more volatile body, and evaporating speedily in the air without leaving any residuum. The pure protochloride is a highly limpid fluid, and perfectly colourless. Its specific gravity is 1.5526. It is a non-conductor of electricity. By Dr. Wollaston's determination its refractive power is 1.4875, being very nearly that of camphor. It is not combustible, except when held in a flame, as of a spirit lamp ; and then it burns with a bright yellow light, much smoke, and fumes of muriatic CAR 296 CAR acid. It does not become solid at the zero of Fahrenheit's scale. When its temperature is raised under the surface of water to between 160 and 170 F. it is converted into vapour, and remains in that state until the temperature is lowered. It is insoluble in water ; but it dissolves readily, in alcohol and ether, the fixed and volatile oils. It is not soluble in alkaline or acid solutions. At a high temperature oxygen decomposes it, forming carbonic oxide or acid, with dis- engagement of chlorine. Chlorine converts it into the perchloride. With iodine it forms a brilliant red solu- tion. When hydrogen and the vapour of the pro- tochloiide are passed through a red-hot tube, there is a complete decomposition. Muriatic acid gas is formed, and charcoal is deposited. The mixed vapour and the gas burn witli flame as they arrive in the hot part of the tube. Sulphur and phosphorus dissolve in it; and the latter decomposes it at a red heat. Its action on metals and metallic oxides is very similar to that of the perchloride. By an analysis conducted in the same way as that of the perchloride, Mr. Faraday ascertained that this liquid chloride is composed of 1 prime proportion of chlorine, and 1 of carbon, or by weight, Chlorine, - 4.5 Carbon, '"^" 0-75 3. Sitbchloride of carbon. This compound was brought to England, and given to Mr. Richard Phillips and Mr. Faraday by M. Julin of Abo, in Finland, having been formed during the distillation of green vitriol and nitre for the production of nitric acid. It is a solid crystalline body, fusible and volatile by heat without decomposition, and condens- ing into crystals. It is insoluble in water; but soluble in alcohol, ether, and essential oils. It sinks in water. It burns with a red flame, giving off much smoke, and fumes of muriatic acid gas. Acids do not act on it. When its vapour is highly heated in a tube, decom- position takes place, chlorine is given off, and charcoal deposited. Potassium burnt with it forms chloride of potassium, and liberates charcoal. Its vapour, detonated with oxygen over mercury, formed carbonic acid and chlo- ride of mercury ; passed over hot oxide of copper, it formed a chloride of copper and carbonic acid ; and over hot liuie, it occasioned ignition, and produced chloride of calcium, and carbonic acid. It is formed of 1 prime proportion of chlorine, and 2 of carbon. In numbers, of chlorine, 4.5 75 carbon, 1.5 25 100 All attempts to form it by other means have failed. We are also indebted to Mr. Faraday foe a triple compound of iodine, carbon, and hydrogen. When iodine and olefiant gas are exposed together in a retort to the sunbeams, there are formed, after some time, colourless crystals, and a partial vacuum is produced. The re- siduary elastic fluid is olefiant gas. The free iodine is removed by a solution of potash, when the new compound is obtained pure. It is a solid, white, crystalline body, with a sweet taste, and aromatic smell. It sinks readily in sulphuric acid of 1.85. It is friable; and is a non-conductor of electricity. When heated, it first fuses, and then sublimes without any change. Its vapour condenses into crystals, which are either prisms or plates. On becoming solid after fusion, it also crystallizes in plates. The crystals are transparent. At a high heat it is decomposed, and iodine evolved. It is not readily combustible. It is insoluble in water, and in alkaline and acid solutions ; but it is soluble in alcohol and ether ; from which solutions it may be obtained by evapo- ration in crystals. CARBONATES. Compounds of car- bonic acid with the salifiable bases. They are composed either of one prime of the acid and one of the base, or of two of the acid and one of the base. The former set of compounds is called carbonates, the latter bicarbonates. See CARBONIC ACID. As the system of chemical equivalents, or atomic theory of chemical combination, de- rives some of its fundamental or prime pro- portions from the constitution of the carbonates, their analysis requires peculiar precautions. In the Annals of Philosophy for October, 1817, I gave a description of a new instrument for accomplishing this purpose with the mi- nutest precision. The usual mode of analysis is to put a given weight of the carbonate in a phial, and add to it a certain quantity of a liquid acid, which will dissolve the base, and disengage the carbonic acid. I found, with every care I could take in this method, that variable and uncertain quantities of the liquid acid were apt to be carried off in vapour with the car- bonic gas, while a portion of this gaseous acid was generally retained in the saline liquid. Hence, in the analysis of crystallized carbonate of lime, the most uniform of all compounds, we have the following discordant results, which are of importance in the doctrine of equiva- lents: Mr. Kirwan makes it consist of 45 acid 4- 55 lime, MM. Aiken, 44 4- 56 Dr. Marcet, 43.9 + 56.1 Dr. Wollaston, 43.7 + 56.3 M. Vauquelin, 43.5 -f 56.5 M. Thenard, 43.28 4- 56.72 Dr. Thomson, 43.137 +56.863 If we deduce the equivalent of lime from the analysis of Dr. Marcet, so well known CAR 297 CAR for his philosophical accuracy, we shall have, These are introduced into the empty tube, and lime = 35.1 to carbonic acid 27-5. made to slide gently along into the spheroid. I adduced the following experiments, se- The instrument is then held in nearly a ho- lected from among many others, as capable of rizontal position with the left hand, the top of throwing light on the cause of these variations: the spheroid resting against the breast, with a small funnel bent at its point, inserted into Into a small pear-shaped vessel of glass with a long neck, and furnished with a hollow spherical stopper, drawn out, above and below, into a tube almost capillary, some dilute mu- riatic acid was put. The whole being poised in a delicate balance, 100 grains of calc spar in rhomboidal fragments were introduced, and the stopper was quickly inserted. A little while after the solution was completed, the diminution of weight, indicating the loss of carbonic acid, was found to be 42.2 grains. Withdrawing the stopper, inclining the vessel to one side for a few minutes, to allow the dense gas to flow out, the diminution became 43.3. Finally, on heating the body of the vessel to about 70, while the hollow stopper was kept cool, small bubbles of gas escaped from the liquid, and the loss of weight was found to be 43.65, at which point it was sta- tionary. This is a tedious process." The instrument which I subsequently employed is quick in its operation, and still more accurate in its results. It consists of a glass tube of the same strength and diameter with that usually employed for barometers, having a strong egg-shaped bulb, about 2 inches long, and 1-| wide, blown at one of its ends, while the other is open and recurved like a syphon. The straight part of the tube, between the ball and bend, is about 7 inches long. The ca- pacity, exclusive of the curved part, is a little more than 5 cubic inches. It is accurately graduated into cubic inches and hundredth parts, by the successive additions of equal weights of quicksilver, from a measure ther- mometric tube. Seven troy ounces and 66 grains of quicksilver occupy the bulk of one cubic inch. Four and a half such portions being introduced will fill the ball, and the beginning of the stem. The point in the tube, which is a tangent to the surface of the mer- cury, is marked with a file or a diamond. Then 34^ grains, equal in volume to l-100th of a cubic inch, being drawn up into the ther- mo'metric tube, rest at a certain height, which is also marked. The same measure of mer- cury is successively introduced and marked off, till the tube is filled. " In the instrument thus finished, 1 -200th of a cubic inch occupies on the stem about 1-14 of an inch, a space very distinguishable. The weight of carbonic acid equivalent to that number, is less than l-400th of a grain. The mode of using it is perfectly simple and com- modious, and the analytical result is com- monly obtained in a few minutes.'' For example, fivB grains of calcareous spar in three or four rhomboids were weighed with great care in a balance by Creighton, which turns with -jTnftnny of the weight in the scales. the orifice of the tube. Quicksilver is now poured in till it be filled, which in this position is accomplished in a few seconds. Should any particles of air be entangled among the mer- cury, they are discharged by inverting the in- strument, having closed the orifice with the finger. On reverting it, and tapping the ball with the finger, the fragments of spar rise to the top. Three or four hundredth parts of a cubic inch of mercury being displaced from the mouth of the tube, that bulk of dilute muriatic acid is poured in ; then pressing the forefinger on the orifice, and inclining the instrument forwards, the acid is made to rise through the quicksilver. This, as it is dis- placed by the cooled carbonic acid, falls into a stone- ware or glass basin, within which tne instrument stands in a wooden frame. When the solution is completed, the apparent volume of gas is noted, the mercury in the two legs of the syphon is brought to a level, or the differ- ence of height above the mercury in the basin is observed, as also the temperature of the apartment, and the height of the barometer. Then the ordinary corrections being made, we have the exact volume of carbonic acid con- tained in five grains of calc spar. In very nu- merous experiments, which I have made in very different circumstances of atmospherical pressure and temperature, the results have not varied one-hundredth of a cubic inch, on five grains, care being had to screen the instrument from the radiation of the sun or a fire. As there is absolutely no action exercised on mercury by dilute muriatic acid at ordi- nary temperatures; as no perceptible differ- ence is made in the bulk of air, by introducing to it over the mercury a little of the acid by itself; and as we can expel every atom of car- bonic acid from the muriate of lime, or other saline solution, by gently heating that point of the tube which contains it, it is evident that the total volume of gaseous product must be accurately determined. When a series of ex- periments is to be performed in 'a short space of time, I wash the quicksilver with water, dry it with a sponge first, and then with warm muslin. The tube is also washed out and drained. According to my experiments with the above instrument, 5 grains of calcareous spar yield 4.7 cubic inches of carbonic acid, equivalent to 43.616 per cent. The difference between this number and Dr. Wollaston's is inconsiderable. Among other results which I obtained from the use of the above instrument, it enabled me to ascertain the true composition of the sub- limed carbonate of ammonia, which chemists had previously mistaken. I showed in the CAR 298 CAR Annals of Philosophy for September, 1817, that this salt contained 54.5 of carbonic acid, 30.5 ammonia, and 15 water, in 100 parts; numbers which, being translated into the Ian- guage of equivalents, approach to the follow- ing proportions : Carbonic acid, 3 primes, 8.25 55.80 Ammonia, 2 4.26 28.86 Water, 2 2.25 15.25 14.76 100.00 As this volatile salt possesses the curious property of passing readily from one system of definite proportions to another, absolute accordance between experiment and theory cannot be expected. The other salt gave for its constituents, 54.5 carbonic acid -f- 22.8 ammonia + 22.75 water = 100. Now, if these numbers be referred to Dr. Wollaston's oxygen scale, we shall have, Theory. Expt. 2 primes carbonic acid, 5.50 55.66 54.50 1 ammonia, 2.13 21-56 22.80 2 water, 2.25 22.78 22.75 These near approximations to the equiva- lent ratios, in compounds of a variable nature, do not seem to have attracted notice at the time. In the 14th Number of the Journal of Science, Mr. Phillips, whose attention to mi- nute accuracy is well known, has published an ingenious paper on the subject, which be- gins with the folio wing hand some acknowledg- ment of my labours : " During some late re- searches, my attention being directed to the composition of the carbonates of ammonia, I began, and had nearly completed an examina- tion of them, before I observed that they had been recently analyzed by Dr. Ure ; and I consider his results to be so nearly accurate, that I should have suppressed mine, if I had not noticed some circumstances respecting the compounds in question, which have, I believe, hitherto escaped observation." Mr. Phillips's communication is valuable. It presents a luminous systematic view of the carbonates of ammonia and soda. The indications of the above analytical in- strument are so minute, as to enable us, by the help of the old and well-known theorem for computing the proportions of two metals from the specific gravity of an alloy, to de- duce the proportions of the bases from the volume of gas disengaged by a given weight of a mixed carbonate. A chemical problem of this nature was practically solved by me, in presence of two distinguished Professors of the University of Dublin, in May 1816. But such an application is more curious than use- ful, since a slight variation in the quantity of gas, as well as accidental admixtures of other substances, are apt to occasion considerable errors. It determines, however, the nature and value of a limestone with sufficient prac- tical precision. As 100 grains of magnc- sian limestone yield 99 cubic inches of gas, a convenient rule for it is formed when we say, that 10 grains will yield 10 cubic inches. In the same way, marles and common lime- stones may be examined, by subjecting a cer- tain number of grains, in a graduated syphon tube, to the action of a little muriatic acid over mercury. From the bulk of evolved gas, ex- pressed in cubic inches and tenths, deduct l-20th, the remainder will express the propor- tion of real limestone present in the grains employed. CARBONATE OF BARYTES. See WlTHERITE. CARBONATE OF LIME. See CAL- CAREOUS SPAR. CARBONATE OF STRONTIAN. See STRONTIAK and HEAVY SPAR. CARBONIC ACID. See ACID (CAR- BONIC). CARBONIC OXIDE. A gaseous com- pound of one prime equivalent of carbon, and one of oxygen, consisting by weight of 0.75 of the former, and 1.00 of the latter. Hence the prime of the compound is 1-75, the same as that of azote. This gas cannot be formed by the chemist by the direct combination of its constituents ; for at the temperature requisite for effecting an union, the carbon attracts its full dose of oxygen, and thus generates carbo- nic acid. It may be procured by exposing charcoal to a long-continued heat. The last products consist chiefly of carbonic oxide. '> To obtain it pure, however, our only plan is to abstract one proportion of oxygen from carbonic acid, either in its gaseous state, or as condensed in the carbonates. Thus by intro- ducing well calcined charcoal into a tube tra- versing a furnace, as is represented Plate I. fig. 2. ; and when it is heated to redness, pass- ing over it backwards and forwards, by means of two attached mercurial gasometers or blad- ders, a slow current of carbonic acid, we con- vert the acid into an oxide more bulky than itself. Each prime of the carbon becomes now associated with only one of oxygen, in- stead of two, as before. The carbon acting here by its superior mass, is enabled to effect the thorough saturation of the oxygen. M. Dumas has proposed a new method of procuring carbonic oxide. He mixes salt of wood-sorrel (superoxalate of potash) with 5 or 6 tunes its weight of sulphuric acid, in -a retort, and causing the mixture to boil, obtains a considerable quantity of a gas, composed of equal parts of carbonic acid, and carbonic oxide. Absorbing the acid by caustic potash, or lime, he has pure carbonic oxide. This method may be successfully employed to exa- mine the salt of wood -sorrel of commerce. Supertartrate of potash treated in the same way would afford oxide of carbon, sulphurous acid, carbonic acid, and the liquid would be- come eventually black, in consequence of the evolution of charcoal. Pure superoxalate of CAR 299 CAR potash, on the contrary, never gives out sul- phurous acid ; and the sulphuric acid em- ployed remains perfectly limpid and colour- less. Jf we subject to a strong heat, in a gun barrel or retort, a mixture of any dry earthy carbonate, such as chalk, or carbonate of stron- tites, with metallic filings or charcoal, the combined acid is resolved as before into the gaseous oxide of carbon. The most conve- nient mixture is equal parts of dried chalk and iron, or zinc filings. By passing a numerous succession of electric explosions through one volume of carbonic acid, confined over mer- cury, two volumes of carbonic oxide, and one of oxygen, are formed, according to Sir H. Davy. The specific gravity of this gas is stated by Gay Lussac and Thenard, from theoretical considerations, to be 0.96782, though Mr. Cruickshank's experimental estimate was 0.95G9. As the gas is formed .by withdraw- ing from a volume of carbonic acid half a vo- lume of oxygen, while the bulk of the gas remains unchanged, we obtain its specific gra- vity by subtracting from that of carbonic acid half the specific gravity of oxygen. Hence 1.5277 0.5555 = 0.9722, differing slightly from the above, in consequence of the French chemists rating the specific gravity of the two original gases at 1.51961 and 1.10359. Hence 100 cubic inches weigh 29 grains at mean pressure and temperature. This gas burns with a dark blue flame. Sir H. Davy has shown, that though carbonic oxide in its combustion produces less heat than other inflammable gases, it may be kindled at a much lower temperature. It inflames in the atmosphere, when brought into contact with an iron wire heated to dull redness, whereas carburetted hydrogen is not inflammable by a similar wire, unless it is heated to whiteness, so as to burn with sparks. It requires, for its combustion, half its volume of oxygen gas, producing one volume of carbonic acid. It is not decomposable by any of the simple com- bustibles, except potassium and sodium. When potassium is heated in a portion of the gas, potash is formed with the precipitation of charcoal, and the disengagement of heat and light. Perhaps iron, at a high temperature, would condense the oxygen and carbon by its strong affinity for these substances. Water condenses ^ of its bulk of the gas. The above processes are those usually prescribed in our systematic works, for procuring the oxide of carbon. In some of them a portion of car- bonic acid is evolved, which may be withdrawn by washing the gaseous product with weak solution of potash, or milk of lime. We avoid the chance of this impurity by extricating the gas from a mixture of dry carbonate of barytes and iron filings, or of oxide of zinc, and pre- viously calcined charcoal. The gaseous pro- duct, from the first mixture, is pure oxide of carbon. Oxide of iron, and pure barytes, re- main in the retort Carbonic oxide, when respired, is fatal to animal life. Sir H. Davy took three inspirations of it, mixed with about one-fourth of common air; the effect was a temporary loss of sensation, which was suc- ceeded by giddiness, sickness, acute pains in different parts of the body, and extreme debi- lity. Some days elapsed before he entirely re- covered. Since then, Mr. Witter of Dublin was struck down in an apoplectic condition, by breathing this gas ; but he was speedily re- stored by the inhalation of oxygen. See an interesting account of this experiment, by Mr. Witter, in the Phil. Mag. vol. 43. When a mixture of it and chlorine is ex- posed to sunshine, a curious compound, dis- covered by Dr. John Davy, is formed, to which he gave the name of phosgene gas. I shall describe its properties in treating of chlo- rine. It has been called chlorocarbonic acid, though chlorocarbonous acid seems a more ap- propriate name. CARBUNCLE, a gem highly prized by the ancients, probably the alamandine^ a va- riety of noble garnet. CARBURET OF SULPHUR. Called also sulphuret of carbon, and alcohol of sul- phur. This interesting liquid was originally ob- tained by Lampadius in distilling a mixture of pulverized pyrites and charcoal in an earthen retort, and was considered by him as a pecu- liar compound of sulphur and hydrogen. But MM. Clement and Desormes, with the pre- cision and ingenuity which distinguish all then- researches, first ascertained its true constitution to be carburetted sulphur ; and they invented a process of great simplicity, for at once pre- paring it, and proving its nature. Thoroughly calcined charcoal is to be put into a porcelain tube, that traverses a furnace at a slight angle of inclination. To the higher end of the tube, a retort of glass, containing sulphur, is luted ; and to the lower end is attached an adopter tube, which enters into a bottle with two tubu- lures, half full of water, and surrounded with very 'cold water or ice. From the other aper- ture of the bottle, a bent tube proceeds into the pneumatic trough. When the porcelain tube is brought into a state of ignition, heat is ap- plied to the sulphur, which subliming into the tube, combines with the charcoal, forming the liquid carburet. The conclusive demonstra- tion of such an experiment was however ques- tioned by M. Berthollet, jun. and Cluzel. But MM. Berthollet, Thenard, and Vauquelin, the reporters on M. CluzeFs memoir, having made some experiments of their own upon the subject, concluded that the liquid in question was a compound of sulphur and carbon only. Finally, an excellent paper was written on the carburet by M. Berzelius and Dr. Marcet, CAR 300 CAR who confirmed the results of MM. Clement and Desormes, and added likewise several important facts. If about ten parts of well calcined charcoal in powder, mixed with fifty parts of pulverized native pyrites (bisulphuret of iron), be dis- tilled from an earthen retort, into a tubulated receiver surrounded with ice, more than one part of sulphuret of carbon may be obtained. If we employ the elegant process of M. Cle- ment, we must take care that the charcoal be perfectly calcined, otherwise no carbonate will be obtained. In their early experiments, they attached to the higher end of the porcelain tube a glass one, containing the sulphur in small pieces, and pushed these successively forwards by a wire passing air-tight through a cork, at the upper end of the tube. Besides the liquid carburet there is formed some carburetted and sulphuretted hydrogen, and a reddish-brown solid and very combustible matter, which seems to be sulphur slightly carburetted. This substance remains almost entirely in the adopter tube. The liquid car- buret occupies the bottom of the receiver bottle, and may be separated from the super- natant water, by putting the whole into a funnel, whose tube is closed with the finger, and letting the denser brown carburet flow out below, whenever the distinction of the liquid mto two strata is complete. Thus obtained, the carburet is always yellowish, containing a small excess of sulphur, which may be re- moved by distillation from a glass retort, plunged in water, at a temperature of 115. It is now transparent and colourless, of a pe- netrating, fetid smell, arid an acrid burning taste. Its specific gravity varies from 1-263 to 1-272. According to Dr. Marcet, it boils i>elbw 110; according to M. Thenard, at 113 F. ; and the tension of its vapour at 72-5 is equivalent toa column of 12-53 inches of mercury. At 53-5, according to Marcet and Berzelius, the tension is equivalent to a column of 7-4 inches, or one-fourth of the mean atmospheric pressure ; hence one-third is added to the bulk of any portion of air, with which the liquid may be mixed. A spirit of wine thermometer, having its bulb surrounded with cotton cloth or lint, if dipped in sulphuret of carbon, and suspended in the air, sinks from 6'0 to 0. If it be put into the receiver of an air-pump, and a moderate exhaustion be made, it sinks rapidly from 60 to 81. If a tube containing mercury be treated in the same way, the mercury may be readily frozen even in summer. The drier the air in the receiver, the more easily is the cold produced. Hence the presence of sulphuric acid may be of some service in removing the vapour from the air in the receiver. This carburet may be cooled to 80 with- out congealing ; a conclusive proof that com- bination changes completely the constitution of bodies, since two substances usually solid form a fluid which we cannot solidify. When a lighted body approaches the surface of the carburet, it immediately catches fire, and burns with a blue sulphurous flame. Carbonic and sulphurous acids are exhaled, and a little sulphur is deposited. A heat of about 700 inflames the vapour of the carburet. Oxygen dilated by it over mercury exploded by the electric spark, with a violent detonation. My eudiometer is peculiarly adapted to the exhi- bition of this experiment. A portion of oxygen being introduced into the sealed leg, we pour a few drops of the carburet on the surface of the mercury in the open leg, and closing this with the finger, transfer the liquid to the other by a momentary inclination of the syphon. The expansion of volume can be now most accurately measured by bringing the mercury to a level in each leg. The subsequent explosion occasions no danger, and a scarcely audible report. The result is a true analysis, if we have mixed oxygen saturated with the vapour, at ordinary pressure and temperature, with about its volume of pure oxygen ; otherwise, all the sulphur would not be oxygenated. We obtain, then, sulphurous and carbonic acids, with the excess of oxygen. The carburet of sulphur dissolves camphor. It does not unite with water ; but very readily with alcohol and ether. With chloride of azote it forms a non -detonating compound. The waters of potash, barytes, and lime, slowly decompose it, with the evolution of carbonic acid gas. It combines with ammonia and lime, forming carbo-sulphurets. The carburet, saturated with ammoniacal gas, forms a yel- low pulverulent substance, which sublimes unaltered in close vessels, but is so deliquescent that it cannot be passed from one vessel to another without absorbing moisture. When heated in that state, crystals of hydrosulphu- ret of ammonia form. The compound with lime is made by heating some quicklime in a tube, and causing the vapour of carburet to pass through it. The lime becomes incan- descent at the instant of combination. When the carburet is left for some weeks in contact with nitro-muriatic acid, it is con- verted into a substance having very much the appearance and physical properties of cam- phor ; being soluble in alcohol and oils, and insoluble in water. This substance is, accord- ing to Berzelius, a triple acid, composed of two atoms of muriatic acid, one atom of sul- phurous acid, and one atom of carbonic acid. He calls it, muriatico-sulphurous-carbonic acid. When potassium is heated in the vapour of the carburet, it burns with a reddish flame, and a black film appears on the surface. On admitting water, a greenish solution of sul- phuret of potash is obtained, containing a CAR 301 CAR mixture of charcoal. From its vapour passing through ignited muriate of silver, without oc- casioning any reduction of the metal, it is demonstrated that this carburet is destitute of hydrogen. When the compound of potash, water, and carburet of sulphur, is added to metallic solutions, precipitates of a peculiar kind, called carbo-sulphurets, are obtained. The following is a table of the colours of the precipitates : Muriate of cerium, White or yellowish- white. Sulphate of manga- nese, Greenish -grey. Sulphate of zinc, White. Peraiuriate of iron, Dark red. Submuriate of anti- mony, Orange. Muriate of tin, Pale orange, then brown. Nitrate of cobalt, Dark olive-green, at last black. Nitrate of lead, A fine scarlet. Nitrate of copper, Dark brown. Protomuriate of mer- cury, Black. Permuriate of mer- cury, Orange. Muriate of silver, Keddish-brown. Carburet of sulphur was found, by Dr. Brewster to exceed all fluid bodies in refractive power, and even the solids, flint-glass, topaz, and tourmaline. In dispersive power it ex- ceeds every fluid substance except oil of cassia, holding an intermediate place between phos- phorus and balsam of Tolu. The best method of analyzing the carburet of sulphur is to pass its vapour over ignited peroxide of iron ; though the analysis was skilfully effected by MM. Berthollet, Vau- quelin, and Thenard, by transmitting the vapour through a red-hot copper tube, or a porcelain one containing copper turnings. Both the first method, as employed by Ber- zelius, and the second, concur in showing the carburet to consist of 1 prime of carbon, 0-75 15-79 2 primes of sulphur, 4-00 84-21 4-75 100-00 Vauquelin's experimental numbers are. from 15 to 16 carbon, and from 86 to 85 sulphur ; and those of Berzelius and Marcet are 15-17 carbon, and 84-83 sulphur, in 100 parts. Of the cold produced by the evaporation of the carburet of sulphur, the following account is given by Dr. Thomson in the third volume of his Annals, being the extract of a letter which he received from Mr. J. Murray, phi- losophical lecturer:" A glass of water has remained on the table since the preceding evening, and though it might be some degrees below 32 Fahr. it indicated no disposition for congelation. A few drops of sulphuret of carbon were applied to the surface ; instantly the globules becamfe cased with a shell of icy spiculas of retiform texture. Where they were in contact with the water, plumose branches darted from the sulphuret as from a centre to the bottom of the vessel, and the whole be- came solidified. The sulphuret of carbon in the interim volatilized ; and during this period the spicules exhibited the colours of the solar spectrum in beautiful array." CARBURET TED HYDROGEN GAS. Of this compound gas, formerly called heavy inflammable air, we have two species, differing in the proportions of the constituents. The first, consisting of 1 prime equivalent of each, is carburetted hydrogen ; the second, of 1 prime of carbon, and 2 of hydrogen, is subcarbu- retted hydrogen. 1. Carburetted hydrogen, the percarburetted hydrogen of the French chemists, is, according to Mr. Brande, the only definite compound of these two elements. To prepare it, we mix, in a glass retort, 1 part of alcohol and 4 of sulphuric acid, and expose the retort to a moderate heat. The gas is usually received over water; though De Saussure states that this liquid absorbs more than l-7th of its volume of the gas. It is destructive of animal life. Its specific gravity is 0-978, according to Saussure. 100 cubic inches weigh 28-80 gr. It possesses all the mechanical properties of air. It is invisible and void of taste and smell, when it has been washed from a little ethereous vapour. The effect of heat on this gas is curious. When passed through a porcelain tube, heated to a cherry-red, it lets fall a portion of charcoal, and nearly doubles its volume. At a higher tem- perature it deposits more charcoal, and aug- ments in bulk ; till finally, at the greatest heat to which we can expose it, it lets fall almost the whole of its carbon, and assumes a volume 3^- times greater than it had at first. These remarkable results, observed with great care, have induced the illustrious Berthollet to conclude, with much plausibility, that hy- drogen and carbon combine in many successive proportions. The transmission of a series of electric sparks through this gas produces a similar effect with that of simple heat. Carburetted hydrogen burns with a splendid white flame. When mixed with three tunes its bulk of oxygen, and kindled by a taper or the electric spark, it explodes with great vio- lence, and the four volumes are converted into two volumes of carbonic acid. But two volumes of carbonic acid contain two volumes of oxygen. The remaining volume of oxygen therefore has been expended in forming water with two volumes of hydrogen. Hence the original volume of carburetted hydrogen was made up of these two volumes of hydrogen 0-1388 (0-0694 X 2) + 2 volumes of gaseous carbon = 0-8333, constituting 1 condensed volume = 0-9722. By gaseous carbon is meant the vapour of this solid, as it exists in CAR 302 CAR carbonic acid ; the density of which vapour Is found by subtracting the specific gravity of oxygen from that of carbonic acid. Hence 1-5277 Mill = 0-4166, represents the density of gaseous carbon. M. Thenard says, that if we mix the percarburetted hydrogen at once with three times its volume of oxygen, the eudiometer would be broken ; so sudden and powerful is the expansion. The eudiometer referred to is that of Volta, which costs three guineas in Paris. My eudiometer, which does not cost three shillings, bears the explosive violence of the above mixture, without any larger. (See EUDIOMETER). When it is detonated with only an equal volume of oxy- gen, it expands greatly, and the two volumes become more than three and a half. In this case only l-8th or l-10th of a volume of car- bonic acid is formed, but more than a volume and a half of carbonic oxide : a little hydrogen is consumed, but the greatest part remains untouched and mixed with the carbonic ox- ide. It may be separated by combustion with chlorine. If we refer the weights above found, from the combining volumes, to the equivalent oxygen scale, we shall have the gas consisting of 1 prime of each constituent. For 0-1388 : 0-125: : 8333 : 0-752; now 0-125 and 0-750 represent the prime equiva- lents of hydrogen and carbon. When this gas is mixed with its own bulk of chlorine, the gaseous mixture is condensed over water into a peculiar oily-looking com- pound. Hence this carburetted hydrogen was called by its discoverers, the associated Dutch chemists, olefiant gas. MM. Robiquet and Colin formed this liquid in considerable quan- tities, by making two currents of its consti- tuent gases meet in a glass globe. The olefiant gas should be in rather larger quantity than the chlorine, otherwise the liquid becomes of a green colour, and acquires acid properties. When it is washed with water, and distilled off dry muriate of lime, it may be regarded as pure. It is then a limpid colourless essence of a pleasant flavour, and a sharp, sweet, and not disagreeable taste. At 45 its specific gravity is 2-2201. Its boiling point is 152. At 49 its vapour is said to be capable of sus- taining a column of 24f inches of mercury. The specific gravity of the vapour is 3.4434, compared to atmospheric air. But that quan- tity is the sum of the densities of chlorine and olefiant gas. It will consist therefore by weight of Olefiant gas, 0-9722 (2 X 0-875) 1-75 Chlorine, 2-500 4-50 3-4722 6-25 or two primes of the first, and one of the se- cond. Its ultimate constituents are therefore 1 chlorine, 2 carbon, and 2 hydrogen. This essence burns with a green flame, from which charcoal is deposited, and muriatic acid gas flies off. Decomposition, with similar results, is effected by passing the liquid through a red-hot porcelain tube. Its constitution pro- bably resembles that of muriatic ether. Olefiant gas is elegantly analyzed by heat- ing sulphur in it over mercury. One cubic inch of it, with 2 grains of sulphur, yields 2 cubic inches of sulphuretted hydrogen, and charcoal is deposited. Now we know that the latter gas contains just its own volume of hy- drogen. 2. Subcarburetted hydrogen. This gas is supposed to be procured in a state of definite composition, from the mud of stagnant pools or ditches. We have only to fill a wide-mouthed goblet with water, and inverting it in the ditch-water, stir the bottom with a stick. Gas rises into the goblet. The fire-damp of mires is a similar gas to that of ditches. There is in both cases an admixture of carbonic acid, which lime or potash water will remove. A proportion of air is also present, the quantity of which can be ascertained by analysis. By igniting acetate of potash in a gun-barrel, an analogous spe- cies of gas is obtained. According to M. Berthollet, the sp. gr. of the carburetted hydrogen from ditch mud, exclusive of the azot3, is 0-5382. Subcarburetted hydrogen is destitute of colour, taste, and smell. It burns with a yellow flame, like that of a candle. When mixed with twice its volume of oxygen and exploded, we obtain exactly its own bulk of car- bonic acid, while water is precipitated. We can hence infer the composition of Subcarbu- retted hydrogen. For of the two volumes of oxygen, one remains gaseous in the carbonic acid, and another is condensed with two volumes of hydrogen into water. 1 volume of vapour of carbon -f- 2 volumes of hydrogen, condensed into 1 volume, compose subcarbu- retted hydrogen gas. Thus in numbers, 1 volume of gaseous carbon =0.41 66 2 do. hydrogen =0.1388 (0.125 0.5554 0.75 = 1 prime 2) = 0.25 = 2 primes 1.00 Here we see the specific gravity 0-5554 is very near the determination of Berthollet. We also perceive the compound prime to be 1 -000, the same as oxygen. Berthollet says that the carburetted hydrogen obtained by exposing olefiant gas to an intense heat contains 2 of hydrogen to 1 of carbon by weight. This proportion corresponds to 12 primes of hydrogen =1-5 And 1 do. of carbon =0-?5 CAR 303 CAR As the gas of ditches and the choke-damp of mines is evidently derived from the action of water on decaying vegetable or carbona- ceous matter, we can understand that a similar product will be obtained by passing water over ignited charcoal, or by heating moistened char- coal or vegetable matter in retorts. The gases are here, however, a somewhat complex mix- ture, as well as what we obtain by igniting pit-coal and wood in iron retorts. (See COAL GAS). The combustion of subcarburetted hydrogen with common air takes place only when they are mixed in certain proportions. If from 6 to 12 ptrts of air be mixed with one of carburetted hydrogen, we have explosive mixtures. Proportions beyond these limits will not explode. In like manner, from 1 to 2~ of oxygen must be mixed with one of the combustible gas, otherwise we have no ex- plosion. Sir H. Davy says that this gas has a disagreeable empyreumatic smell, and that water absorbs l-30th of its volume of it. See OIL GAS. CARICA PAPAYA. Papaw tree. Every part of the papaw tree, except the ripe fruit, affords a milky juice, which is used in the Isle of France as an effectual remedy for the tape- worm. In Europe, however, whither it has been sent in the concrete state, it has not answered. The most remarkable circumstance regard- ing the papaw tree, is the extraction from its juice of a matter exactly resembling the flesh or fibre of animals, and hence called vegetable fibrin ; which see. CARINTHINE. A sub-species of the mineral Augi'ce. Colour black. Occurs mas- sive and disseminated. Internally splendent. Resino-vitreous. Distinct cleavage of 124 34'. Fracture conchoidal. Greenish-black variety; translucant on the edges, velvet-black, opaque. Occurs in the Saualpe in Carinthia, in a bed in primitive rock, associated with quartz, kyanite, garnet, and zoizite. Jame- son. CARMINE. A red pigment prepared from cochineal. See LAKE. CARNELIAN is a sub-species of calce- dony. Its colours are white, yellow, brown, and red. It has a conchoidal fracture, and a specific gravity of 2.6. It is semitransparent, and has a glistening lustre. It consists of 94 silica, 3.5 alumina, and 0-75 oxide of iron. The finest specimens come from Cambay and Surat in India. It is found in the channels of torrents in Hindostan, in nodules of a blackish-olive, passing into grey. After ex- posure for some weeks to the sun, these are subjected to heat in earthen pots, whence pro- ceed the lively colours for which they are valued in jewellery. It is softer than common calcedony. CAROMEL. The smell exhaled by su- gar, at a calcining heat. CARPHOLITE. This mineral is yellow, but sometimes colourless. It occurs in mi- nute crystals, generally in a radiating form ;, also amorphous. In this state it is white. Sp. grav. 2.935. It consists of, silica 37-53 ; alumina 26.47; oxide of manganese 18.33; protoxide cf iron 6.27; water 11.36. It fuses at the blowpipe with intumescence, whitens, and then becomes a brown opaque glass. It is found at Schlackenwalde in Bo- hemia. Phillips' s Mineralogy. CARTHAMUS, SAFFLOWER, or BASTARD SAFFRON. In some of the deep reddish, yellow, or orange-coloured flowers, the yellow matter seems to be of thd(/: same kind with that of the pure yellow flowers; but the red to be of a different kind from the pure red ones. Watery menstrua take up only the yellow, and leave the red, which may afterward be extracted by alcohol, or by a weak solution of alkali. Such particularly are the saffron-coloured flowers of carthamus. These, after the yellow matter has been ex- tracted by water, are said to give a tincture to ley ; from which, on standing at rest for some time, a deep red fecula subsides, called saf- flower, and from the countries whence it is commonly brought to us, Spanish red and China lake. This pigment impregnates alco- hol with a beautiful red tincture ; but commu- nicates no colour to water. Rouge is prepared from carthamus. For this purpose the red colour is extracted by a solution of the subcarbonate of soda, and pre- cipitated by lemon juice previously depurated by standing. This precipitate is dried on earthen plates, mixed with talc, or French chalk, reduced to a powder by means of the leaves of shave-grass, triturated with it till they are both very fine, and then sifted. The fine- ness of the powder and proportion of the pre- cipitate constitute the difference between the finer and cheaper rouge. It is likewise spread very thin on saucers, and sold in this state for dyeing. Carthamus is used for dyeing silk of a poppy, cherry, rose, or bright orange-red. After the yellow matter is extracted as above, and the cakes opened, it is put into a deal trough, and sprinkled at different times with pearl ashes, or rather soda, well powdered and sifted, in the proportion of six pounds to a hundred, mixing the alkali well as it is put in. The alkali should be saturated with carbonic acid. The carthamus is then put on a cloth in a trough with a grated bottom, placed on a larger trough, and cold water poured on, till the larger trough is filled. And this is repeated, with the addition of a little more alkali toward the end, till the carthamus is exhausted and become yellow. Lemon juice is then poured into the bath, till it is turned of a fine cherry colour, and after it is well stirred, the silk is immersed in it. The silk is wrung, drained, and passed through fresh baths, washing and drying after every operation, till it is of a pro- CAS 304 CAT per colour ; when it is brightened in hot water and lemon juice. For a poppy or fire colour a slight annotto ground is first given ; but the Silk should not be alumed. For a pale car- nation a little soap should be put into the bath. All these baths must be used as soon as they are made, and cold, because heat destroys the colour of the red feculae. CARTILAGE. An elastic, semitranspa- rent, animal solid, which remains of the shape, and one-third the weight of the bones, when the calcareous salts are removed by digestion in dilute muriatic acid. It resembles coagu- lated albumen. Nitric acid converts it into gelatin. With alkalis it forms an animal soap. Cartilage is the primitive paste, into which the calcareous salts are deposited in the young animal. In the disease rickets, the earthy matter is withdrawn by morbid absorption, and the bones return into the state nearly of flexible cartilage. Hence arise the distortions characteristic of this disease. CASE-HARDENING. Steel when har- dened is brittle, and iron alone is not capable of receiving the hardness steel may be brought to possess. There is nevertheless a variety of articles in which it is desirable to possess all the hardness of steel, together with the tough- ness of iron. These requisites are united in the art of case-hardening, which does not differ from the making of steel, except in the shorter duration of the process. Tools, utensils, or ornaments intended to be polished, are first manufactured in iron and nearly finished, after which they are put into an iron box, together with vegetable or animal coals in powder, and cemented for a certain time. This treatment converts the external part into a coating of steel, which is usually very thin, because the time allowed for the cementation is much shorter than when the whole is in- tended to be made into steel. Immersion of the heated pieces into water hardens the sur- face, which is afterward polished by the usual methods. Moxon's Mechanic Exercises, p. 56. gives the following receipt: Cow's horn or hoof is to be baked or thoroughly dried, and pulverized. To this add an equal quantity of bay salt: mix them with stale chamber- ley, or white wine vinegar : cover the iron with this mixture, and bed it in the same in loam, or enclose it in an iron box : lay it then on the hearth of the forge to dry and harden : then put it into the fire, and blow till the lump have a blood-red heat, and no higher, lest the mixture be burned too much. Take the iron out, and immerse it in water to harden. CASEIC ACID. The name which Proust gave to a substance of an acid nature, which he extracted from cheese; and to which he ascribes many of the properties of this species of food. CASSAVA. An American plant, the jatropha mani/tat, contains the nutritive starch cassava, curiously associated with a deadly poisonous juice. The roots of jatropha arc squeezed in a bag. The cassava remains in it ; and the juice, which is used by the In- dians to poison their arrows, gradually lets fall some starch of an innocent and very nu- tritious quality. The whole solid matter is dried in smoke, ground, and made into bread. CASSIUS'S Purple Precipitate. See GOLD. CASTOR. A soft greyish-yellow or light- brown substance, found in four bags in the inguinal region of the beaver. In a warm air it grows by degrees hard and brittle, and of a darker colour, especially when dried in chimneys, as is usually done. According to Bouillon La Grange, it consists of a mucilage, a bitter extract, a resin, an essential oil, in which its peculiar smell appears to reside, and a flaky crystalline matter, much resembling the adipocere of biliary calculi. Castor is regarded as a powerful antispas- modic. CASTORINA. A light powder precipi- tated from alcohol which had been boiled for some time on one sixth its weight of castor. On redissolution in hot alcohol, prismatic acicular crystals were obtained; diaphonous and white. These dissolve readily in ether. When heated they fuse and appear to boil, emitting vapours which burn brilliantly in the air. They do not give ammonia in destruc- tive distillation. Bizio in the Gior. dc Fisicu, vii. 174. CATECHU. A brown astringent sub- stance, formerly known by the name of Japan earth. It is a dry extract, prepared from the wood of a species of sensitive plant, the mi- mosa catechu. It is imported into this country from Bombay and Bengal. According to Sir H. Davy, who analyzed it, that from Bombay is of uniform texture, red-brown colour, and specific gravity 1.39 : that from Bengal is more friable and less consistent, of a chocolate colour externally, but internally chocolate streaked with red-brown, and specific gravity 1.28. The catechu from either place differs little in its properties. Its taste is astringent, leaving behind a sensation of sweetness. It is almost wholly soluble in water. Two hundred grains of picked catechu from Bombay afforded 109 grains of tannin, 66 extractive matter, 13 mucilage, 10 residuum, chiefly sand and calcareous earth. The same quantity from Bengal : tannin 97 grains, ex- tractive matter 73, mucilage 16, residual mat- ter, being sand, with a small quantity of cal- careous and aluminous earths, 14. Of the latter, the darkest parts appeared to afford most tannin, the lightest most extractive mat- ter. The Hindoos prefer the lightest coloured, which has probably most sweetness, to chew with the betel-nut. Of all the astringent substances we know, catechu appears to contain the largest pro- CEL 305 CEM portion of tannin ; and Mr. Purkis found, that one pound was equivalent to seven or eight of oak bark for the purpose of tanning leather. As & medicine it has been recommended as a powerful astringent, and a tincture of it is used for this purpose; but its aqueous solu- tion is less irritating. Made into troches with gum arabic and sugar, it is an elegant prepa- ration, and in this way is said much to assist the clearness of the voice, and to be remarkably serviceable in disorders of the throat. CAT'S EYE. A mineral of a beautiful appearance, brought from Ceylon. Its colours are grey, green, brown, red, of various shades. Its internal lustre is shining, its .fracture imperfectly coachoidal, and it is translucent. From a peculiar play of light, arising from white fibres interspersed, it has derived its name. The French call the ap- pearance chatoyant. It scratches quartz, is easily broken, and resists the blowpipe. Its sp. gr. is 2.64. Its constituents are, according to Klaproth, 95 silica, 1.75 alumina, 1.5 lime, and 0.25 oxide of iron. It is valued for setting as a precious stone. CAUSTIC (LUNAR). Fused nitrate of silver. See SILVER. CAUSTICITY. All substances which have so strong a tendency to combine with the principles of organized substances as to destroy their texture, are said to be caustic. The chief of these are the concentrated acids, pure alkalis, and the metallic salts. CAUTERY (POTENTIAL). See CAUSTIC. CAWK. A term by which the miners distinguish the opaque specimens of sulphate of barytes. CELESTINE. Native sulphate of stron- tites. This mineral is so named from its occasional delicate blue colour ; though it is frequently found of other shades, as white, greyish, and yellowish white and red. It occurs both massive and crystallized. Some- times also in fibrous and stellated forms. According to Hatty, the primitive form is a right rhomboidal prism, of 104 48' and 75 12'. The reflecting goniometer makes these angles 104 and jti . The varieties of its crystals may be referred to four or six-sided prisms, terminated by two, four, or eight- sided summits. It has a shining lustre, and is either transparent, translucent, or opaque. It scratches calcareous spar, but is scratched by fluor. It is very brittle- Its sp. gr. is 3.6. Before the blowpipe it fuses into a white, opaque, and friable enamel. The three sub-species are, 1st, The com- pact found in Montmartre near Paris, of a yellowish-grey colour, in rounded pieces, of a dull lustre, opaque, and consisting, by Vau- quelin's analysis, of 01.42 sulphate of stron- tites, 8.33 carbonate of lime, and 0.25 oxide of iron. 2d, The fibrous, whose colours are indigo-blue and bluish-grey ; sometimes white. It occurs both massive and crystallized. Shining and somewhat pearly lustre. It is translucent. Sp. grav. 3.83. 3d, The foli- ated, of a milk-white colour, falling into blue. Massive and in grouped crystals, of a shining lustre and straight foliated texture. Trans- lucent. Celestine occurs most abundantly near Bristol in the red marie formation j ar.d crystallized in red sandstone, at Inverness in Scotland. Mr. Gruner Ober Berg of Hanover has lately favoured the world with an analysis o^Bfc crystallized celestine, found in the ncfghbou[H hood of that city, of rather peculiar compdT" sition. Its sp. gr. is only 3.59, and yet it contains a large proportion of sulphate of barytes : Sulphate of strontites, 73.000 Sulphate of barytes, 26.166 Ferruginous clay, 0.213 Loss, 0.621 100.000 Had the result been 75 of sulphate of stron- tites -f 25 sulphate of barytes, we should have considered the mineral as a compound of 4 primes of the first salt + 1 of the second. Now the analysis, in my opinion, cannot be confided in within these limits; for the mingled muriates of the earths were separated by di- gestion in 16 times their weight of boiling al- cohol, of a strength not named. Besides, the previous perfect conversion of the sulphates into carbonates, by merely fusing the mineral with thrice its weight of carbonate of potash, is, to say the least, problematical. Dr. Thom- son adapts M. Ober Berg's analysis to 7 atoms of sulphate of strontian, and 2 atoms of sulphate of barytes. CEMENT. Whatever is employed to unite or cement together things of the same or different kinds, may be called a cement. In this sense it includes LUTES, GLUES, and SOLDEHS of every kind, which sec; but it is more commonly employed to signify those of which the basis is an earth or earthy salt. See LIME. We shall here enumerate, chiefly from the Philosophical Magazine, some ce- ments that are used for particular purposes. Seven or eight parts of resin, and one of wax, melted together, and mixed with a small quantity of plaster of Paris, is a very good cement to uaite pieces of Derbyshire spar, or other stone. The stone should be made hot enough to melt the cement, and the pieces should be pressed together as closely as pos- sible, so as to leave as little as may be of the cement between them. This is a general rule in cementing, as the tb inner the stratum of cement interposed, the firmer it will hold. Melted brimstone used in the Name way will answer sufficiently well, if the joining be not required to be very strong. CEM 306 CEM > It sometimes happens, that jewellers, in setting precious stones, break off pieces by ac- cident ; in this case they join them so that it cannot easily be seen, with gum mastic, the stone being previously made hot enough to melt it. By the same medium cameos of white enamel, or coloured glass, are often joined to a real stone as a ground, to produce the appearance of an onyx. Mastic is likewise used to cement false backs or doublets to stones, to alter their hue. The jewellers in Turkey, who are generally Armenians, ornament watch-cases and other trinkets with gems, by glueing them on. The ^Rone is set in silver or gold, and the back of the setting made flat to correspond with the part to which it is to be applied. It is then fixed on with the following cement : Isinglass, soaked in water till it swells up and becomes soft, is dissolved in French brandy, or in rum, so as to form a strong glue. Two small bits of gum galbanum, or gum ammoniacum, are dissolved in two ounces of this by trituration ; and five or six bits of mastic, as big as pease, being dissolved in as much alcohol as will render them fluid, are to be mixed with this by means of a gentle heat. This cement is to be kept in a phial closely stopped; and when used, it is to be liquefied by immersing the phial in hot water. This cement resists moisture. A solution of shell lac in alcohol, added to a solution of isinglass in proof spirit, makes another cement that will resist moisture. So does common glue melted without water, with half its weight of resin, with the addition of a little red ochre to give it a body. This is particularly useful for cementing hones to their frames. , t ;, If clay and oxide of iron be mixed with oil, according to Mr. Gad of Stockholm, they will form a cement that will harden under water. A strong cement, insoluble in water, may be made from cheese. The cheese should be that of skimmed milk, cut into slices, throwing away the rind, and boiled till it becomes a strong glue, which, however, does not dissolve in the water. This water being poured off, it is to be washed in cold water, and then kneaded in warm water. This process is to be repeated several times. The glue is then to be put warm on a levigating stone, and kneaded with quicklime. This cement may be used cold, but it is better to warm it; and it will join marble, stone, or earthen-ware, so that the joining is scarcely to be discovered. Boiled linseed oil, litharge, red lead, and white lead, mixed together to a proper consist- ence, and applied on each side of a piece of flannel, or even linen or paper, and put between two pieces of metal before they are brought home, or close together, will make a close and durable joint, that will resist boiling water, or even a considerable pressure of steam. The proportions of the ingredients are not material ; but the more the red lead predominates, the sooner the cement will dry, and the more the white lead, the contrary. This cement answers well for joining stones of any dimensions. The following is an excellent cement for iron, as in time it unites with it into one mass. Take two ounces of muriate of ammonia, one of flowers of sulphur, and 16 of cast-iron filings or borings. Mix them well in a mortar, and keep the powder dry. When the cement is wanted for use, take one part of this mixture, twenty parts of clear iron borings or filings, grind them together in a mortar, mix them with water to a proper consistence, and apply them between the joints. Powdered quickliine mixed with bullock's blood is often used by coppersmiths, to lay over the rivets and edges of the sheets of copper in large boilers, as a security to the junctures, and also to prevent cocks from leaking. Six parts of clay, one of iron filings, and linseed oil sufficient to form a thick paste, make a good cement for stopping cracks in iron boilers. Temporary cements are wanted in cutting, grinding, or polishing optical glasses, stones, and various small articles of jewellery, which it is necessary to fix on blocks, or handles, for the purpose. Four ounces of resin, a quarter of an ounce of wax, and four ounces of whiting made previously red hot, form a good cement of this kind ; as any of the above articles may be fastened to it by heating them, and removed at pleasure in the same manner, though they adhere very firmly to it when cold. Pitch, resin, and a small quantity of tallow, thickened with brick-dust, is much used at Birmingham for these purposes. Four parts of resin, one of bees' wax and one of brick-dust, likewise make a good cement. This answers extremely well for fixing knives and forks in their hafts ; but the manufacturers of cheap articles of this kind too commonly use resin and brick-dust alone. On some occasions, in which a very tough cement is requisite, that will not crack though exposed to repeated blows, as in fast- ening to a block metallic articles that are to be cut with a hammer and punch, workmen usually mix some tow with the cement, the fibres of which hold its parts together. Mr. Singer recommends the following com- position as a good cement for electrical appa- ratus : Five pounds of resin, one of bees' wax, one of red ochre, and two table spoonfuls of plaster of Paris, all melted together. A cheaper one for cementing voltaic plates into wooden troughs is made with six pounds of resin, one pound of red ochre, half a pound of plaster of Paris, and a quarter of a pint of linseed oil. The ochre and plaster of Paris should be well dried, and added to the other ingredients, in a melted state. CER 307 CER Analysis of water cements by Sir Hum- phrey Davy. Mr. Parker's patent cement. Silex, Alumina, Oxide of Iron, ji And manganese, $ ( 'arbonate of lime, 50 grains contain 11 4.5 6.5 27.5 100 gr. 50 grains lost by heating, 102.25 Loftus. Silex, Alumina, - Oxide of iron, J And manganese, \ Carbonate of lime, Loss by heat, Mulgrave. 50 grains contain 12.75 - 2.5 5.25 27-75 1.25 100 gr. 25.5 5. 10.5 55.5 96.5 2.5 99 50 grains 100 gr. contain Silex, / p 10.5 21 Alumina, - 3J5 7-5 Oxide of iron, 1 And manganese, J Carbonate of lime, C-75 27.5 13.5 55 Loss, 1.C2 97 3.32 100.32. M. Bruyere finds that an excellent artificial water cement may be obtained by heating a mixture of three parts clay, and one part slaked lime by measure, for some hours to redness. Ann. de Mines, ix. 550. CEMENT, for buildings. See LIME. CEMENTATION. A chemical process, which consists in surrounding a body in the solid state with the powder of some other bodies, and exposing the whole for a time in a closed vessel, to a degree of heat not sufficient to fuse the contents. Thus iron is converted into steel by cementation with charcoal ; green bottle glass is converted into porcelain by cementation with sand, &c- See IRON and PORCELAIN. CERASIN. The name given by Dr. John of Berlin to those gummy substances which swell in cold water, but do not readily dissolve in it. Cerasin is soluble in boiling water, but separates in a jelly when the water cools. Water acidulated with sulphuric, nitric, or mu- riatic acid, by the aid of a gentle heat, forms a permanent solution of cerasin. Gum tragacanth is the best example of this species of vegetable product. CERATE. The compound of oil or lard with bees' wax, used by surgeons to screen ulcerated surfaces from the air. CERIN. A peculiar substance which pre- cipitates, on evaporation, from alcohol, which has been digested on grated cork. Subcrcerin would have been a fitter name. Chevreul, thj^| discoverer, describes this substance as consisfl( ing of small white needles, which sink and merely soften in boiling water. 1000 parts of boiling alcohol dissolve 2.42 of cerin, and only 2 of wax. Nitric acid converts it into oxalic acid. It is insoluble in an alcoholic solution of potash. CERIN. The name given by Dr. John to the part of common wax which dissolves in alcohoL CERIN. A variety of the mineral allanite, lately examined by Berzelius. It consists of oxide of cerium 28.19, oxide of iron 20-72, oxide of copper 087, silica 30.17, alumina 1 1.31, lime 9.12, volatile matter 0.40. CERITE. The siliciferous oxide of cerium. This rare mineral is of a rose-red or flesh-red colour, occasionally tinged with clove- brown. Its powder is reddish-grey. It is found massive and disseminated. Internal lustre resinous, but scarcely glimmering. Its fracture is fine splintery, with indeterminate fragments. It is opaque, scratches glass, gives sparks with steel, is difficult to break, scarcely yields to the knife, and gives a greyish-white streak. It is infusible before the blowpipe; but heat changes the grey colour of the powder to yellow. It consists, by Hisinger's analysis, of 18 silica, 68.59 oxide of cerium, 2 oxide of iron, 1.25 lime, 9.6 water and carbonic acid, and 0.56 loss, in 100 parts. Klaproth found 54.5 oxide of cerium, and 34.5 silica, in the hundred parts. It is found only in the cop- per mine of Bastnaes near Riddarhytta in Sweden, accompanied by the ores of copper, molybdena, and bismuth. Its sp. gr. is from 4.6 to 4.9. CERIUM. The metal whose oxide exists in the preceding mineral. To obtain the oxide of the new metal, the cerite is calcined, pulverized, and dissolved in nitromuriatic acid. The filtered solution being neutralized with pure potash, is to be precipi- tated by tartrate of potash ; and the precipitate, well washed, and afterward calcined, is oxide of cerium. The attempts to obtain the pure metal, by igniting the oxide, purified from iron by oxalic acid, in contact with tartaric acid, oil, and lamp-black, have in a great measure failed ; only white brittle carburet was obtained. x2 CER 308 CHA Cerium is susceptible of two stages of oxidation ; in the first it is white, and this by calcination becomes of a fallow-red. The white oxide exposed to the blowpipe soon becomes red, but does not melt, or even agglutinate. With a large proportion of borax it fuses into a transparent globule. The white oxide becomes yellowish in the open air, but never so red as by calcination, because it absorbs carbonic acid, which pre- vents its saturating itself with oxygen, and retains a portion of water, which diminishes colour. Alkalis do not act on it ; but caustic potash in the dry way takes part of the oxygen from the red oxide, so as to convert it into the white without altering its nature. The protoxide of cerium is composed by Hisinger of 85.17 metal -(- 14.83 oxygen, and the peroxide of 79-3 metal + 20.7. The protoxide has been supposed a binary com- pound of cerium 5 75 4- oxygen 1, and the peroxide a compound of 5.75 X 2 of cerium -\- 3 oxygen. An alloy of this metal with iron was obtained by Vauquelin. The salts of cerium are white or yellow- coloured,, have a sweet taste, yield a white precipitate with hydrosulphuret of potash, but none with sulphuretted hydrogen ; a milk- white precipitate, soluble in nitric and muriatic acids, with ferroprussiate of potash and oxalate of ammonia, none with infusion of galls, and a white one with arssniate of potash. Equal parts of sulphuric acid and red oxide, with four parts of water, unite by the assist- ance of heat into a crystalline mass ; which may be completely dissolved by adding more acid, and heating them together a long time. This solution yields, by gentle evaporation, small crystals, some of an orange, others of a lemon colour. The sulphate of cerium is so- luble in water only with an excess of acid. Its taste is acid and saccharine. The sulphuric acid combines readily with the white oxide, particularly in the state of carbonate. The solution has a saccharine taste, and readily affords white crystals. Nitric acid does not readily dissolve the red oxide without heat. With an excess of acid, white deliquescent crystals are formed, which are decomposable by heat. Their taste is at first pungent, afterward very sugary. The white oxide unites more readily with the acid. Muriatic acid dissolves the red oxide with effervescence. The solution crystallizes con- fusedly. The salt is deliquescent, soluble in an equal weight of cold water, and in three or four times its weight of alcohol. The flame of this solution, if concentrated, is yellow and sparkling ; if not, colourless ; but on agitation it emits white, red, and purple sparks. Carbonic acid readily unites with the oxide. This is best done by adding carbonate of pot- ash to the nitric and muriatic solution of the white oxide, when a light precipitate will be thrown down, which on drying assumes a shining silvery appearance, and consists of 23 acid + C5 oxide -f- 12 water. The white oxide unites directly with tar- taric acid, but requires an excess to render it soluble. See SALT. CERUMEN of the ear. It is a yellow- coloured secretion, which lines the external auditory canal, rendered viscid and concrete by exposure to air. It has a bitter taste, melts at a low heat, and evolves a slightly aromatic odour. On ignited coals, it gives out a white smoke, similar to that of burning fat, swells, emits a fetid ammoniacal odour, and is con- verted into a light coal. Alcohol dissolves of it, and on evaporation leaves a substance re- sembling the resin of bile. The f which re- main are albumen mixed with oil, which by incineration leave soda and phosphate of lime. Hence, the whole constituents are five; albu- men, an inspissated oil, a colouring matter, soda, and calcareous phosphate. CERUSE, or WHITE LEAD. See LEAD. CETINE. The name given by Chevreul to spermaceti. According to Berard, who analyzed it on M. Gay Lussac's plan, by passing its vapour through ignited peroxide of copper, cetine consists of 81 carbon, G oxygen, and 13 hydrogen, in 100 parts. CEYLANITE. This mineral, the pleo- naste of Hatty, comes from Ceylon, commonly in rounded pieces, but occasionally in crystals. The primitive form of its crystals is a regular octohedron, in which form, or with the edges truncated, it frequently occurs. Its colour is indigo-blue, passing into black, which on mi- nute inspection appears greenish. It has a, rough surface, with little external lustre, but splendent internally. The fracture is perfect flat conchoidal, with very sharp-edged frag- ments. It scarcely scratches quartz, and is softer than spinell. It is easily broken, has a sp. gr. of 3.77, and is infusible by the blow- pipe. CHABASITE. This mineral occurs in crystals, whose primitive foim is nearly a cube, since the angle at the summit is only 93. It is found in that form, and clso with 6 of its edges truncated, and the truncatures united 3 and 3 at the two opposite angles, while the other six angles are truncated. It occurs also in double six-sided pyramids, applied base to base, having the six angles at the base, and the three acute edges of each pyramid trun- cated. It is white, or with a tinge of rose co- lour, and sometimes transparent It scratches glass, fuses by the blowpipe into a white spongy mass, and has a sp. gr. of 2-72. Its constituents are 43.33 silica, 22.66 alumina, 3.34 lime, 9.34 soda and potash, water 21. It is found in scattered crystals in the fissures of some trap rocks, and in the hollows of cer- tain gcodcs, disseminated in the same rocks. CHA 309 CHA It occurs in the quarry of Alteberg near Ober- stein. CHALK. A very common species of cal- careous earth, of an opaque white colour, very soft, and without the least appearance of a polish in its fracture. Its specific gravity is from 2.4 to 2.6, according to Kirwan. It con- tains a little siliceous earth, and about two per cent, of clay. Some specimens, and perhaps most, contain a little iron, and Bergmann affirms that muriate of lime, or magnesia, is often found in it ; for which reason he directs the powder of chalk to be several times boiled in distilled water, before it is dissolved for the purpose of obtaining pure calcareous earth. CHALK (BLACK). Drawing slate. The colour of .this mineral is greyish or bluish- black. Massive. The principal fracture is glimmering and slaty, the cross fracture dull, and fine earthy. It is in opaque, tabular fragments, stains paper black, streak glisten- ing, and the same colour as the surface ; easily cut and broken ; sp. gr. 2.4 ; becomes red in the fire, and falls to pieces in water. It occurs in primitive mountains, often accompanied by alum slate. It is used in crayon drawing, whence its name. CHALK STONES. Gouty concretions, whose true nature was first discovered by Dr. Wollaston, and described by him in his ad- mirable dissertation on urinary calculi, pub- lished in the Phil. Trans, for 1797- See GOUTY CONCRETIONS. CHALK (RED). This is a clay, coloured by the oxide of iron, of which it contains from 1C to 18 parts in the hundred, according to Rinman. CHALK (SPANISH). The soap rock is frequently distinguished by this name. CHALYBEATE. Said of a mineral water impregnated with iron. CHAMELEON MINERAL. See CA- MELEON. CHARACTERS (CHEMICAL). The chemical characters were invented by the earlier chemists, probably with no other view than to save time in writing the names of substances that frequently occurred, in the same manner as we avoid repetitions by the use of pronouns. But the moderns seem to have considered them as relics of alchemistical obscurity, and have almost totally rejected their use. Very little of system appears in the ancient characters of chemists : the characters of Bergmann are chiefly grounded on the ancient characters, with additions and improvements. But the characters of Hassenfratz and Adet are sys- tematical throughout. For myself, I regard them merely as the means of mystifying che- mistry in the eyes of the uninitiated, and there- fore unworthy of the liberal spirit of the age in which we live. mere wen CHARCOAL. When vegetabk sub- stances are exposed to a strong heat in the apparatus for distillation, the fixed residue is called charcoal. For general purposes, wood is converted into charcoal by building it up in a pyramidal form, covering the pile with clay or earth, and leaving a few air-holes, which are closed as soon as the mass is well lighted ; and by this means the combustion is carried on in an imperfect manner. In the forest of Benon, near Rochelle, great attention is paid to the manufacture, so that the charcoal made there fetches 25 or 30 per cent, more than any olh The wood is that of the black oak. It is t ' from ten to fifteen years old, the trunk as we, as the branches, cut into billets about four feet long, and not split. The largest pieces, how- ever, seldom exceed six or seven inches in diameter. The end that rests on the ground is cut a little sloping, so as to touch it merely with an edge, and they are piled nearly upright, but never in more than one story. The wood is covered all over about four inches thick with dry grass or fern, before it is enclosed in the usual manner with clay ; and when the wood is charred, half a barrel of water is thrown over the pile, and earth to the thickness of five or six inches is thrown on, after which it is left four-and-twcnty hours to cool. The wood is always used in the year in which it is cut. In charring wood it has been conjectured, that a portion of it is sometimes converted into a pyrophorus, and that the explosions that happen in powder-mills are sometimes owing to this. Charcoal is made on the great scab, by igniting wood in iron cylinders, as I have de- scribed under ACID (ACETIC). When the resulting charcoal is to be used in the manu- facture of gunpowder, it is essential that the last portion of vinegar and tar be suffered to escape, and that the reabsorption of the crude vapours be prevented, by cutting off the com- munication between the interior of the cylinders and the apparatus for condensing the pyro- lignous acid, whenever the fire is withdrawn from the furnace. If this precaution be not observed, the gunpowder made with the char- coal would be of inferior quality. In the third volume of Tilloch's Magazine, we have some valuable facts on charcoal by Mr. Mushet. He justly observes, that the produce of charcoal in the small way differs from that on the large scale, in which the quantity of char depends more upon the hard- ness and compactness of the texture of wood, and the skill of the workmen in managing the pyramid of faggots, than on the absolute quan- tity of carbon it contains. The following is his table of results, reduced to 100 parts, from experiments on one pound avoirdupois of wood. CHA 310 CHE Parts in 100. Oak, Ash, Birch, Norway Pine, Mahogany, Sycamore, Holly, Scotch Pine, Beech, Elm, Walnut, American Maple, Do. Black Beech, Laburnum, Lignum Vitae, Sallow, Chesnut, Charcoal. Ashes. 76.895 22.682 0.423 81.260 17.972 0.768 80.717 17-491 1.792 80.441 19.204 0.355 73.528 25.492 0.980 79.20 19.734 1.066 78.92 19.918 1.162 83.095 16.456 0.449 79.104 19.941 0.95T) 79.655 19.574 0.761 78.521 20.663 0.816 79.331 19.901 0.768 77-512 21.445 1.033 74.234 24.586 1.180 72.643 26.857 0.500 80.371 18.497 1.132 76.304 23.280 0.416 Charcoal by Proust. Rumforu. 20. 17. 20. Black Ash. 25. Willow. 17- Heart of Oak. 19. Guaiacum. 24. 43.00 44.18 43.27 42.23 Poplar. 43.57 Lime. 43.59 MM. Clement and Desormes say, that wood contains one-half its weight of charcoal. M. Proust says, that good pit-coals afford 70, 75, or 80 per cent, of charcoal or coke ; from which only two or three parts in the hundred of ashes remain after combustion. Tillocti's Mag. vol. viii. Charcoal is black, sonorous, and brittle, and in general retains the figure of the vegetable it was obtained from. If, however, the vegetable consist for the most part of water or other fluids, these in their extrication will destroy the con- nexion of the more fixed parts. In this case the quantity of charcoal is much less than in the former. The charcoal of oily or bitumi- nous substances is of a light pulverulent form, and rises in soot. This charcoal of oils in called lamp-black. A very fine kind is ob- tained from burning alcohol. Turf or peat has been charred lately in France, it is said by a peculiar process, and, according to the account given in Sonnini's Journal, is superior to wood for this purpose. Charcoal of turf kindles slower than that of wood, but emits more flame, and burns longer. In a goldsmith's furnace it fused eleven ounces of gold in eight minutes, while wood charcoal required sixteen. The malleability of the gold, too, was preserved in the former instance, but not in the latter. Iron heated red-hot by it in a forge, was rendered more malleable. From the scarcity of wood in this country, pit-coal charred is much used instead of char- coal by the name of coke. See CARBON. CHAY, or CHAYA-ROOT. This is the root of the Oldenlandia umbellata, which grows wild on the coast of Coromandel, and is likewise cultivated there for the use of the dyers and calico-printers. It is used for the same purposes as madder with us, to which it is said to be far superior, giving the beautiful red so much admired in the Madras cottons. CHEESE. Milk consists of butter, cheese, a saccharine matter called sugar of milk, and a small quantity of common salt, together with much water. If any vegetable or mineral acid be mixed with milk, the cheese separates, and, if as- sisted by heat, coagulates into a mass. The quantity of cheese is less when a mineral acid is used. Neutral salts, and likewise all earthy and metallic salts, separate the cheese from the whey. Sugar and gum-arabic produce the same effect. Caustic alkalis will dissolve the curd by the assistance of a boiling heat, and acids occasion a precipitation again. Ve- getable acids have very little solvent power upon curd. This accounts for a greater quan- tity of curd being obtained when a vegetable acid is used. But what answers best is rennet, which is made by macerating in water a piece of the last stomach of a calf, salted and dried for this purpose. Scheele observed, that cheese has a con- siderable analogy to albumen, which it re- sembles in being coagulable by fire and acids, soluble in ammonia, and affording the same products by distillation or treatment with ni- tric acid. There are, however, certain dif- ferences between them. Rouelle observed like- wise a striking analogy between cheese and the gluten of wheat, and that found in the fecuke of green vegetables. By kneading the gluten of wheat with a little salt and a small CHE 811 CHL portion of a solution of starch, he gave it the taste, smell, and unctuosity of cheese ; so that after it had been kept a certain time, it was not to be distinguished from the celebrated Rochefort cheese, of which it had all the pun- gency. This caseous substance from gluten, as well as the cheese of milk, appears to con- tain acetate of ammonia, after it has been kept long enough to have undergone the requisite fermentation, as may be proved by examining it with sulphuric acid, and with potash. The pungency of strong cheese, too, is destroyed by alcohol. In the llth volume of Tilloch's Magazine there is an excellent account of the mode of making Cheshire cheese, taken from the Agri- cultural Report of the county. wt If the milk," says the reporter, " be set together very warm, the curd, as before observed, will be firm ; in this case, the usual mode is to take a common case-knife, and make incisions across it, to the full depth of the knife's blade, at the distance of about one inch ; and again crossways in the same manner, the incisions intersecting each other at right angles. The whey rising through these incisions is of a fine pale green colour. The cheese-maker and two assistants then proceed to break the curd : this is per- formed by their repeatedly putting their hands down into the tub ; the cheese-maker, with the skimming-dish in one hand, breaking every part of it as they catch, it, raising the curd from the bottom, and still breaking it. This part of the business is continued till the whole is broken uniformly small ; it generally takes up about 40 minutes, and the curd is then left covered over with a cloth for about half an hour to subside. If the milk has been set cool together, the curd, as before mentioned, will be much more tender, the whey will not be so green, but rather of a milky appearance." CHEMISTRY may be defined the science which investigates the composition of material substances, and the permanent changes of con- stitution which their mutual actions produce. CHENOPODIUM OLIDUM. A plant remarkable, according to MM. Chevalier and Lasseigue, for containing uncombiued am- monia, which is probably the vehicle of the. remarkably nauseous odour which it exhales, strongly resembling that of putrid fish. When the plant is bruised with water, and the liquor expressed and afterwards distilled, we procure a fluid which contains the subcarbonate of am- monia, and an oily matter, which gives the fluid a milky appearance. If the expressed juice of the chenopodium be evaporated to the consistence of an extract, it is found to be al- kaline ; there seems to be acetic acid in it. Its basis is said to be of an albuminous nature. It is stated also to contain a small quantity of the substance which the French call osmazome, a little of an aromatic resin, and a bitter mat- ter, soluble both in alcohol and water, as well as several saline bodies. The following is stated as the result of their analysis, which, however, seems somewhat complex : 1. Sub- carbonate of ammonia. 2. Albumen. 3. Os- mazome. 4. An aromatic resin. 5. A bitter matter. C. Nitrate of potash in large quan- tity. 7- Acetate and phosphate of potash. 8. Tartrate of potash. It is said that 100 parts of the dried plant produce 18 of ashes, of which 5^ are potash. CHERT. See HORNSTONE. CHIASTOLITE. A mineral crystallized in four-sided nearly rectangular prisms. On looking into the end of the prism, we percei in the axis of it a blackish prism, surrou by the other, which is of a greyish, yellowis or reddish-white colour. From each angle of the interior prism, a blackish line extends to the corresponding angle of the exterior. In each of these outer angles there is usually a small rhomboidal space, filled with the same dark substance which composes the central prism- The black matter is the same clay- slate with the rock in which the chiastolite is embedded. Fracture, foliated with double cleavage. Translucent. Scratches glass. Rubbed on sealing-wax, it imparts negative electricity. Its sp. gr. is 2.94. Before the blowpipe it is convertible into a whitish ena- mel. The only mineral with which chiastolite or made can be confounded, were it not crys- tallized, is steatite ; but the latter communi- cates positive electricity to sealing-wax. It has been found in Britanny, in the Pyrenees, in the valley of Barege, and in Galicia in Spain, near St. James of Compostella. The interior of black crystal is properly an elon- gated four-sided pyramid. CHILDRENITE. A mineral substance met with in Devonshire, supposed at first to be carbonate of iron ; but shown by Dr. Wol- laston to be a phosphate of alumina and iron. The crystals scratch glass ; colour wine-yel- low; occur in the surface of crystallized quartz, and might be mistaken for sulphate of barytes. Mr. Brooke, in Annals of Phil. vii. 316. CHLORATES. Compounds of chloric acid with the salifiable bases. See ACID (CHLORIC.) CHLORIC ACID. See ACID (CHLO- RIC.) CHLORIDES. Compounds of chlorine with different bodies. See CHLORINE and the respective substances. CHLORINE. The introduction of this term marks an era in chemical science. It originated from the masterly researches of Sir H. Davy on the oxy muriatic acid gas of the French school : a substance which, after re- sisting the most powerful means of decom- position which his sagacity could invent, or his ingenuity apply, he declared to be, according to the true logic of chemistry, an elementary body, and not a compound of muriatic acid and oxygen, as was previously imagined, and CHL 312 CHL as its name seemed to denote. He accordingly assigned to it the term chlorine, descriptive of its colour ; a name now generally used. The ehloridic theory of combustion, though more limited in its applications to the chemical phe- nomena of nature, than the antiphlogistic of Lavoisier, may justly be regarded as of equal i'Tiporiai'ce to the advancement of the science itself. When we now survey the Transactions of tho Royal Society for 1808, 1809, 1810, and loll, we feel overwhelmed with astonish- ment at the unparalleled skill, labour, and ^^agacity by which the great English chemist, Hp so short a space, prodigiously multiplied "^The objects and resources of the science, while he promulgated a new code of laws, flowing from views of elementary action, equally pro- found, original, and sublime. The importance 01 the revolution produced by his researches on chlorine will justify us in presenting a de- tailed account of the steps by which it has been effected . How entirely the glory of this great work belongs to Sir H. Davy, notwith- standing some invidious attempts in this coun- ft* try to tear the well-earned laurel from his brow, and transfer it to the French chemists, we may readily judge by the following decisive facts. The second part of the Phil. Trans, for 1809 contains researches on oxymuriatic acid, its nature and combinations, by Sir H. Davy, from which I shall make a few interesting ex- tracts. "In the Bakerian lecture for 1808," says he, " 1 have given an account of the action of potassium upon muria ic acid gas, by which more than one-third of its volume of hydro- gen is produced; and I have stated, that muriatic acid can in no instance be procured from oxymuriatic acid, or from dry muriates, unless water or its elements be present. " In the second volume of the Memoires D'Arcueil, MM. Gay Lussac and Thenard have detailed an extensive series of facts, upon muriatic acid, and oxymuriatic acid. Some of their experiments are similar to those I have detailed in the paper just referred to ; others are peculiaily their own, and of a very curious kind : their general conclusion is, that mu- riatic acid gas contains about one quarter of its weight of waier ; and that oxymuriatic acid is not decomposable by any substances but hydrogen, or such as can form triple com- binations with it. " One of the most singular facts that I have observed on this subject, and which I have before referred to, is that charcoal, even when ignited to whiteness in oxymuriatic or muriatic acid gases, by the voltaic battery, effects no change in them, if it has been previously freed from hydrogen and moisture by intense ig- nition In vacua. " This experiment, which I have several times repeated, led me to doubt of the exist- ence of oxygen in that substance, which has been supposed to contain it, above all others, in a loose and active state ; and to make a more rigorous investigation, than had hitherto been attempted for its detection." He then proceeds by experiment and rea- soning to prove the true constitution of this muriatic essence. The above paper, and his Bakerian lecture, read before the Royal So- ciety in Nov. and Dec. 1810, and published in the first part of their Transactions lor 181 1 T present the whole body of evidence for the undecompounded nature of oxymuriatic acid gas, thenceforward styled chlorine ; and they will be studied in every enlightened age and country, as a just and splendid pattern of in- ductive Baconian logic. These views were slowly and reluctantly admitted by the che- mical philosophers of Europe. The hypothe- sis of Lavoisier, that combustion was merely the combination of oxygen with a basis, had become as favourite an idol with the learned as the previous hypothesis of Stahl, that one phlogistic principle pervaded all combustible bodies, which was either evolved in heat and light, or quietly transferred to an incombusti- ble, imparting that inflammability to the new substance, which its former companion had secretly lost. Stahl's idea of combustion is the more comprehensive, and may still be true ; Lavoisier's, as a general proposition, is certainly false. In 1812 Sir H. Davy published his Elements of Chemical Philosophy, containing a system- atic account of his new doctrines concerning the combination of simple bodies. Chlorine is there placed in the same rank with oxygen, and fir, ally removed from the class of acids. In 1813, M. Thenard published the first vo- lume of his Traite de Chimie Elemcntaire Thcorique et Pratique. This distinguished chemist, the fellow-labourer of M. Gay Lussac, in those able researches on the alkalis and oxymuriatic acid, which form the distinguish- ed rivalry of the French school to the brilliant career of Sir H. Davy, states at page 584 of the above volume, the composition of oxymu- riatic acid as follows : " Composition. The oxygenated muriatic gas contains the half of its volume of oxygen gas, not including that which we may suppose in muriatic acid. It thence follows, that it is formed of 1.9183 of muriatic acid, and 0.5517 of oxygen; for the specific gravity of oxygenated muriatic gas is 2.47, and that of oxygen gas 1.1034." "M. Che- nevix first determined the proportion of its constituent principles. MM. Gay Lussac and Thenard determined it more exactly, and showed that we could not decompose the oxy- genated muriatic gas, but by putting it in con- tact with a body capable of uniting with the two elements of this gas, or with muriatic acid. They announced at the same time, that they could explain all the phenomena which it presents, by considering it as a simple or as a compound body. However, this last opinion CHL 313 CHL appeared more probable to them. M. Davy, on tbe contrary, embraced the first, admitted it exclusively, and sought to fortify it by ex- periments which are peculiar to him. P. 585. In the second volume of M. Thenard's work, published in 1814, he explains the mu- tual action of chlorine and ammonia gases, solely on the oxygenous theory. " On peut devnontrer par ce dernier procede, que le gas muriatique exigent doit contenir la moitie de son volume d'oxigene, uni a 1'acide muri- atique." P. 147- In the 4th volume, which appeared in 1816. we find the following pass- ages : fct Qteygeitttttd muriatic gas. Oxy- genated muriatic gas, in combining with the metals, gives rise to the neutral muriates. Now, 107.6 of oxide of silver, contain 7-6 of oxygen, and absorb 26.4 of muriatic acid, to pass to the state of neutral muriate. Of con- sequence, 348 of this last acid supposed dry, and 100 of oxygen, form this gas. But the sp. gr. of oxygen is 1.1034, and that of oxy- genated muriatic gas is 2.47; hence, this contains the half of its volume of oxygen. " P. 52. The force of Sir H. Davy's demonstrations, pressing for six years on the public mind of the French philosophers, now begins to trans- pire in a rote to the above passage. "We reason here," says M. Thenard, wc obviously on the hypothesis, which consists in regarding oxygenated muriatic gas as a compound body." This pressure of public opinion becomes con- spicuous at the end of the volume. Among the additions, we have the following decisive evidence of the lingering attachment to the old theory of Lavoisier and Eerthollet t4 A pretty considerable number of persons who have subscribed for this work, desiring a de- tailed explanation of the phenomena which oxygenated muriatic gas presents, on the sup- position that this gas is a simple body, we are now going to explain these phenomena, on this supposition, by considering them atten- tively. The oxygenated muriatic gas will take the name of chlorine ; its combinations with phosphorus, sulphur, azote, metals, will be called chloriires ; the muriatic acid, which results from equal parts in volume of hydro- gen and oxygenated muriatic gases, will be hydrochloric acid ; the superoxygenated mu- liatic acid will be chlorous acid ; and the hy- peroxygenated muriatic, chloric acid ; the iirst, comparable to the hydriodic acid, and tlia last to the iodic acid." In fact, therefore, we evidently see, that so far from the chloridic theory originating in France, as has been more than insinuated, it was only the researches on iodine, so admirably conducted by M. Gay Lussac, that, by their auxiliary attack on the oxygen hypothesis, eventually opened the minds of its adherents to the evidence long a^o advanced by Sir Humphrey Davy. It will be peculiarly instructive, to give a general outline of that evidence, which has been mu- tilated in some systematic works on chemistry, or frittered away into fragments. Sir H. Davy subjected oxymuriatic gas to the action of many simple combustibles, as well as metals, and from the compounds formed, endeavoured to eliminate oxygen, by the most energetic powers of affinity and vol- taic electricity, but without success, as the fol- lowing abstract will show. If oxymuriatic acid gas be introduced into a vessel exhausted of air, containing tin, and the tin be gently heated, and the gas in sufficient quantity, the tin and the gas disap- pear, and a limpid fluid, precisely the same z& Libavius's liquor, is formed : If this substance is a combination of muriatic acid and oxide of tin, oxide of tin ought to be separated from it by means of ammonia. He admitted ammo- niacal gas over mercury to a small quantity of the liquor of Libavius ; it was absorbed with great heat, and no gas was generated ; a solid result was obtained, which was of a dull white colour : some of it was heated, to ascer- tain if it contained oxide of tin ; but the whole volatilized, producing dense pungent fumes. Another experiment of the same kind, made with great care, and in which the ammonia was used in great excess, proved that the liquor of Libavius cannot be decompounded by ammonia ; but that it forms a new com- bination with this substance. He made a considerable quantity of the solid compound of oxymuriatic acid and phos- phorus by combustion, and saturated it with, ammonia, by heating it in a proper receiver filled with ammoniacal gas, on which it acted with great energy, producing much heat ; and they formed a white opaque powder. Sup- posing that this substance was composed of the dry muriates and phosphates of ammonia ; as muriate of ammonia is very volatile, and as ammonia is driven oft" from phosphoric acid by a heat below redness, he conceived that, by igniting the product obtained, he should procure phosphoric acid; he thfrefore intro- duced some of the powder into a tube of green glass, and heated it to redness, out of the con- tact of air, by a spirit lamp ; but found to his great surprise, that it was not at all volatile, nor decomposable at this degree of heat, and that it gave off no gaseous matter. The circumstance, that a substance com- posed principally of oxymuriatic acid, and ammonia, should resist decomposition or change at so high a temperature, induced him to pay particular attention to the properties of this new body. It has been said, and taken for granted by many chemists, that when oxymuriatic acid and ammonia act upon each other, water is formed : he several times made the experi- ment, and was convinced that this is not the case. He mixed together sulphuretted hydrogen in 3 high degree of purity, and oxymuriatic CHL CHL acid gas, both dried, in equal volumes. In this instance the condensation was not ^ ; sulphur, which seemed to contain a little oxy- muriatic acid, was formed on the sides of the vessel ; no vapour was deposited, and the resi- dual gas contained about ^ of muriatic acid gas, and the remainder was inflammable. When oxymuriatic acid is acted upon by nearly an equal volume of hydrogen, a com- bination takes place between them, and muri- atic acid gas results. When muriatic acid gas is acted on by mercury, or any other metal, the oxymuriatic acid is attracted from hydrogen by the stronger affinity of the metal, and an oxymuriate, exactly similar to that formed by combustion, is produced. The action of water upon those compounds which have been usually considered as mu- riates, or as dry muriates, but which are pro- perly combinations of oxymuriatic acid with inflammable bases, may be easily explained, according to these views of the subject. When water is added in certain quantities to Liba- vius's liquor, a solid crystallized mass is ob- tained from which oxide of tin and muriate of ammonia can be procured by ammonia. In this case, oxygen may be conceived to be supplied to the tin, and hydrogen to the oxy- muriatic acid. The compound formed by burning phos- phorus in oxymuriatic acid is in a similar relation to water. If that substance be added to it, it is resolved into two powerful acids ; oxygen, it may be supposed, is furnished to the phosphorus to form phosphoric acid, hy- drogen to the oxymuriatic acid to form com- mon muriatic acid gas. He caused strong explosions from an elec- trical jar to pass through oxymuriatic gas, by means of points of platina, for several hours in succession ; but it seemed not to undergo the slightest change. He electrized the oxymuriates of phospho- rus and sulphur for some hours, by the power of the voltaic apparatus of 1000 double plates. No gas separated, but a minute quantity of hydrogen, which he was inclined to attribute to the presence of moisture in the apparatus employed ; for he once obtained hydrogen from Libavius's liquor by a similar operation. But he ascertained that this was owing to the decomposition of water adhering to the mer- cury : and in some late experiments made with 2000 double plates, in which the dis- charge was from platina wires, and in which the mercury used for confining the liquor was carefully boiled, there was no production of any permanent elastic matter. Few substances, perhaps, have less claim to be considered as acid than oxymuriatic acid. As yet we have no right to say that it has been decompounded ; and as its tendency of combination is with pure inflammable mat- ters, it may possibly belong to the same class of bodies as oxygen. May it not in fact be a peculiar acidifying and dissolving principle, forming compounds with combustible bodies, analogous to acids containing oxygen or oxides, in their proper- ties and powers of combination ; but differing from them, it being for the most part decom- posable by water ? On this idea, muriatic acid may be considered as having hydrogen for its basis, and oxymuriatic acid for its acidifying principle; and the phosphoric sublimate as having phosphorus for its basis, and oxymu- riatic acid for its acidifying matter ; and Liba- vius's liquor, and the compounds of arsenic with oxymuriatic acid, may be regarded as analogous bodies. The combinations of oxy- muriatic acid with lead, silver, mercury, po- tassium, and sodium, in this view, would be considered as a class of bodies related more to oxides than acids, in their powers of attrac- tion. Bak. Lee. 1809. On the Combination of the Common Metals with Oxygen and Oxymuriatic Gas. Sir H. used in all cases small retorts of green glass, containing from three to six cu- bical inches, furnished with stop-cocks. The metallic substances were introduced, the retort exhausted and filled with the gas to be acted upon, heat was applied by means of a spirit lamp, and after cooling, the results were ex- amined, and the residual gas analyzed. All the metals that he tried, except silver, lead, nickel, cobalt, and gold, when heated, burnt in the oxymuriatic gas, and the volatile metals with flame. Arsenic, antimony, tellu- rium, and zinc, with a white flame, mercury with a red flame. Tin became ignited to whiteness, and iron and copper to redness; tungsten and manganese to dull redness ; pla- tina was scarcely acted upon at the heat of fusion of the glass. The product from mercury was corrosive sublimate. That from zinc was similar in colour to that from antimony, but was much less volatile. Silver and lead produced horn-silver and horn-lead ; and bismuth, butter of bismuth. In acting upon metallic oxides by oxymu- riatic gas, he found that those of lead, silver, tin, copper, antimony, bismuth, and tellurium, were decomposed in a heat below redness, but the oxides of the volatile metals more readily than those of the fixed ones. The oxides of cobalt and nickel were scarcely acted upon at a dull red heat. The red oxide of iron was not affected at a strong red heat, whilst the black oxide was readily decomposed at a much lower temperature ; arsenical acid underwent no change at the greatest heat that could be given it in the glass retort, whilst the white oxide readily decomposed- In cases where oxygen was given off', it was found exactly the same in quantity as that which had been absorbed by the metal. Thus CHL 315 CHL iwo grains of red oxide of mercury absorbed 9fi of a cubical inch of oxymuriatic gas, and afforded 0.45 of oxygen. Two grains of dark olive oxide from calomel decomposed by pot- ash, absorbed about -fe of oxymuriatie gas, and afforded ^L. of oxygen, and corrosive sub- limate was produced in both cases. In the decomposition of the white oxide of zinc, oxygen was expelled exactly equal to half the volume of the oxymuriatic acid ab- sorbed. In the case of the decomposition of the black oxide of iron, and the white oxide of arsenic, the changes that occurred were of a very beautiful kind; no oxygen v/as given off in cither case, but butter of arsenic and ar- senical acid formed in one instance, and the ferruginous sublimate and red oxide of iron in the other. General Conclusions and Observations, illus- trated ly Experiments. Oxymuriatic gas combines with inflamma- ble bodies, to form simple binary compounds ; and in these cases, when it acts upon oxides, it either produces the expulsion of their oxy- gen, or causes it to enter into new combina- tions. If it be said that the oxygen arises from the decomposition of the oxymuriatic gas, and not from the oxides, it may be asked, why it is always the quantity contained in the oxide ? and why in some cases, as those of the per- oxides of potassium and sodium, it bears no relation to the quantity of gas ? If there existed any acid matter in oxy- muriatic gas, combined with oxygen, it ought to be exhibited in the fluid compound of one proportion of phosphorus, and two of oxy- muriatic gas ; for this, on such an assumption, should consist of muriatic acid (on the old hypothesis, free from v/ater) and phosphorous acid ; but this substance has no effect on lit- mus paper, and does not act under common circumstances on fixed alkaline bases, such as dry lime or magnesia. Oxymuriatic gas, like oxygen, must be combined in large quantity with peculiar inflammable matter, to form acid matter. In its union with hydrogen, it in- stantly reddens the driest litmus paper, though a gaseous body. Contrary to acids, it expels oxygen from protoxides, and combines with peroxides. When potassium is burnt in oxymuriatic gas, a dry compound is obtained. If potas- sium combined with oxygen is employed, the whole of the oxygen is expelled, and the same compound formed. It is contrary to sound logic to say, that this exact quantity of oxy- gen is given off from a body not known to be compound, when we are certain of its existence in another; and all the cases are parallel. Scheele explained the bleaching powers of the oxymuriatic gas, by supposing that it de- stroyed colours by combining with phlogiston, Bcrthollet considered it as acting by supplying; oxygen. He made an experiment, which seems to prove that the pure gas is incapable of altering vegetable colours, and that its operation in bleaching depends entirely upon its property of decomposing water, and liber- ating its oxygen. He filled a glass globe, containing 'dry powdered muriate of lime, with oxymuriatic gas. He introduced some dry paper tinged with litmus that had been just heated, into another globe containing dry muriate of lime : after some time this globe was exhausted, and then connected with the globe containing the oxymuriatic gas, and by an appropriate set of stop-cocks, the paper was exposed to the action of the gas. No change of colour took place, and after two days there was scarcely a per- ceptible alteration. Some similar paper dried, introduced into gas that had not been exposed to muriate of lime, was instantly rendered white. It is generally stated in chemical books, that oxymuriatic gas is capable of being con- densed and crystallized at a low temperature. He found by several experiments that this is not the case. The solution of oxymuriatic gas in water freezes more readily than pure water, but the pure gas dried by muriate of lime undergoes no change whatever, at a tem- perature of 40 below of Fahrenheit. The mistake seems to have arisen from the expo- sure of the gas to cold in bottles containing moisture. He attempted to decompose boracic and phos- phoric acids by oxymuriatic gas, but without success ; from which it seems probable, that the attractions of boracium and phosphorus for oxygen are stronger than for oxymuriatic gas. And from the experiments already detailed, iron and arsenic are analogous in this respect, and probably some other metals. Potassium, sodium, calcium, strontium, ba- rium, zinc, mercury, tin, lead, and probably silver, antimony, and gold, seem to have a stronger attraction for oxymuriatic gas than for oxygen. " To call a body which is not known to con- tain oxygen, and which cannot contain muriatic acid, oxymuriatic acid, is contrary to the prin- ciples of that nomenclature in which it is adopted ; and an alteration of it seems neces- sary to assist the progress of discussion, and to diffuse just ideas on the subject. If the great discoverer of this substance had signified it by any simple name, it would have been proper to have recurred to it ; but dephlogisti- cated marine acid is a term which can hardly be adopted in the present advanced era of the science. "After consulting some of the most eminent, chemical philosophers in this country, it has been judged most proper to suggest a name founded upon one of its obvious and character- CHL 316 CHL istic properties its colour, and to call it chlorine or chloric gas. tfc Should it hereafter be discovered to be compound, and even to contain oxygen, this name can imply no error, and cannot neces- sarily require a change. " Most of the salts which have been called muriates, are not known to contain any mu- riatic acid, or any oxygen. Thus Libavius's liquor, though converted into a muriate by water, contains only tin and oxymuriatic gas, and horn-silver seems incapable of being converted into a true muriate." Bale. Lee. 1811. We shall now exhibit a summary view of the preparation and properties of chlorine. Mix in a mortar 3 parts of common salt and 1 of black oxide of manganese. Introduce them into a glass retort, and add 2 parts of sulphuric acid. Gas will issue, which must be collected in the water-pneumatic trough. A gentle heat will favour its extrication. In practice, the above pasty-consistenced mixture is apt to boil over into the neck. A mixture of liquid muriatic acid and manganese is there- fore more convenient for the production of chlorine. A very slight heat is adequate to its expulsion from the retort. Instead of man- ganese, red oxide of mercury, or puce-coloured oxide of lead, may be employed. This gas, as we have already remarked, is of a greenish-yellow colour, easily recognized by day-light, but scarcely distinguishable by that of candles. Its odour and taste are dis- agreeable, strong, and so characteristic, that it is impossible to mistake it for any other gas. When we breathe it, even much diluted with air, it occasions a sense of strangulation, con- striction of the thorax, and a copious discharge from the nostrils. If respired in larger quan- tity, it excites violent coughing, with spitting of blood, and would speedily destroy the indi- vidual, amid violent distress. Its specific gravity is 2-5. This is better inferred from the specific gravities of hydrogen and muriatic acid gases, than from the direct weight of chlorine, from the impossibility of confining it over mercury. One volume of hydrogen, added to one of chlorine, form two of the acid gas. Hence, if from twice the specific gravity of muriatic gas 2.5694, we subtract that of hydrogen = 0.0694, the difference 2.5 is the specific gravity of chlorine. 100 cubic inches at mean pressure and temperature weigh 75$ grains. See GAS. Sir H. Davy having suggested (Phil. Trans. 1823) to Mr. Faraday to expose the crystalline hydrate of chlorine (see infra) to heat under pressure, the following experiments were com- menced at his request. Some hydrate of chlo- rine, dried by pressure on bibulous paper, was introduced into a sealed glass tube, the upper end of which was then hermetically closed. Being placed in water at 60 no change was perceived ; but when put into water at 100 the hydrate fused, the tube became filled with a bright yellow atmosphere, and on examina- tion it was found to contain two fluid sub- stances ; the one, about three-fourths of the whole, was of a faint yellow colour, having very much the appearance of water ; the re- maining fourth was a heavy bright yellow fluid, lying at the bottom of the former, with- out any apparent tendency to mix with it. As the tube cooled, the yellow atmosphere con- densed into more of the yellow fluid, which floated in a film on the pale fluid, looking very like chloride of nitrogen. He afterwards succeeded in distilling the yellow fluid to one end of the tube, and so separated it from the remaining portion. When the tube was cut in the middle the parts flew asunder, and a powerful atmosphere of chlorine exhaled. Subsequently, by a condensing syringe, he converted chlorine dried over sulphuric acid into the same yellow liquid. Since then, M. Bussy has liquefied chlorine, by cooling the vessel containing it, with his liquid sul- phurous acid. In its perfectly dry state, the gas has no effect on dry vegetable colours. With the aid of a little moisture, it bleaches them into ti yellowish-white. Scheele first remarked this bleaching property; Berthollet applied it to the art of bleaching in France; and from him Mr. Watt introduced its use into Great Britain. If a lighted wax taper be immersed rapidly into this gas, it consumes very fast, with a dull reddish flame, and much smoke. The taper will not burn at the surface of the gas. Hence, if slowly introduced, it is apt to be extinguished. The alkaline metals, as well as copper, tin, arsenic, zinc, antimony, in fine laminae or filings, spontaneously burn in chlo- rine. Metallic chlorides result. Phosphorus also takes fire at ordinary temperatures, and is converted into a chloride. Sulphur may be melted in the gas without taking fire. It forms a liquid chloride, of a reddish colour. When dry, it is not altered by any change of tem- perature. Enclosed in a phial with a little moisture, it concretes into crystalline needles, at 40 Fahr. According to M. Thenard, water condenses at the temperature of 68 Fahr., and at 29.92 barom. IA times its volume of chlorine, and forms aqueous chlorine, formerly called liquid oxymuriatic acid. This combination is best made in the second bottle of a Woolfc's appa- ratus, the first being charged with a little water, to intercept the muriatic acid gas, while the third bottle may contain potash-water, or milk of lime, to condense the superfluous gas. M. Thenard says, that a kilogramme of salt is sufficient for saturating from 10 to 12 litres of water. These measures correspond to 2-j Ibs. avoirdupois, and to from 21 to 25 pints Eng- lish. There is an ingenious apparatus for making aqueous chlorine, described in Ber- CHL 317 CHL iliollet's Elements of Dyeing, vol. i. ; which, however, the happy substitution of slaked lime for water, by Mr. Charles Tennent of Glasgow, has superseded, for the purposes of manufac- ture. It congeals by cold at 40 Fahr. and affords crystallized plates, of a deep yellow, containing a less proportion of water than the liquid combination. Henc?, when chlorine is passed into water at temperatures under 40, the liquid finally becomes a concrete mass, which at a gentle heat liquefies with effer- vescence, from the escape of the excess of chlo- rine. The hydrate of chlorine may be obtained, well crystallized, by introducing into a clean bottle of the gas a little water, but not suffi- cient to convert the whole into hydrate, and then placing the bottle in a temperature some- what below 32 Fahr. for a few days, in a dark place. The hydrate is produced in a crust, or in dendritical crystals, but, being left to itself, will in a few days sublime from one part of the bottle to another, in the manner of camphor, forming brilliant and comparatively large crystals, which when most perfect are acute flattened octohedra. These crystals con- sist in 100 parts of 27-7 chlorine -\- 72.3 water; which accords with 10 atoms of water to 1 of chlorine. Mr. Faraday, Journal of Science, xv. 71. When steam and chlorine are passed toge- ther through a red-hot porcelain tube, they are converted into muriatic acid and oxygen. A like result is obtained by exposing aqueous chlorine to the solar rays ; with this difference, that a little chloric acid is formed. Hence, aqueous chlorine should be kept in a dark place. Aqueous chlorine attacks almost all the metals at an ordinary temperature, forming muriates or chlorides, and heat is evolved. It has the smell, taste, and colour of chlorine; and acts, like it, on vegetable and animal colours. Its taste is somewhat astringent, but not in the least degree acidulous. When we put in a perfectly dark place, at the ordinary temperature, a mixture of chlo- rine and hydrogen, it experiences no kind of alteration, even in the space of a great many days. But if, at the same low temperature, we expose the mixture to the diffuse light of day, by degrees the two gases enter into che- mical combination, and form muriatic acid gas. There is no change in the volume of the mixture, but the change of its nature may be proved, by its rapid absorbability by water, its not exploding by the lighted taper, and the disappearance of the chlorine hue. To produce the complete discoloration, we must expose the mixture finally for a few minutes to the sun- beam. If exposed at first to this intensity of light, it explodes with great violence, and in- stantly forms muriatic acid gas. The same explosive combination is produced by the elec- tric spark arid the lighted taper. M. Thenard says, a heat of 392 is sufficient to cause the explosion. The proper proportion is an equail volume of each gas. Chlorine and nitrogen combine into a remarkable detonating com- pound, by exposing the former gas to a solu- tion of an ammoniacal salt. See NITROGEN. Chlorine is the most powerful agent for de- stroying contagious miasmata. The disinfect- ing phials of Morveau evolve this gas. Dr. Brown has recently employed chlorine in solution, in cases of the scarlet fever, with the utmost success. From a tea spoonful to a table spoonful is given every two or three hours, without the addition of any other substance. The solution should be fresh made, and swal- lowed quickly to avoid coughing ; in the sore throat sometimes accompanying the fever, it is more easily swallowed than mucilaginous drinks. As the disease declines, the quantity of medicine is diminished : the whole quantity in the cases of children has never exceeded two ounces, and in adults five ounces. For its anticontagious powers, see LIME (CHLORIDE or). See CHLOROUS OXIDE. CHLORITE, is a mineral usually friable or very easy to pulverize, composed of a multi- tude of little spangles, or shining small grains, falling to powder under the pressure of the fingers. There arc four sub-species. \. Chlo- rite earth. In green, glimmering, and some- what pearly scales, with a shining green streak. It adheres to the skin, and has a greasy feel. Spec. grav. 2.6. It consists of 50 silica, 20 alumina, 1.5 lime, 5 oxide of iron, 17.5 pot- ash. This mineral is found chiefly in clay- slate, in Germany and Switzerland. At Alten- berg, in Saxony, it is intermingled with sul- phurets of iron and arsenic ; and amphibole in mass. 2. Common chlorite. A massive mi- neral of a blackish-green colour, a shining lustre, and a foliated fracture passing into earthy. Streak is lighter green; it is soft, opaque, easily cut and broken, and feels greasy. Spec. grav. 2.83. Its constituents are 26 silica, 18.5 alumina, 8 magnesia, 43 oxide of iron, and 2 muriate of potash. 3. Chlorite slate, A massive, blackish-green mineral, with re- sinous lustre, and curve slaty or scaly-foliated fracture. Double cleavage. Easily cut. Feels somewhat greasy. Spec. grav. 2.82. It occurs particularly along with clay-slate, and is found in Corsica, Fahlun in Sweden, and Norway. 4. Foliated chlorite. Colour between moun- tain and blackish-green. Massive ; but com- monly crystallized in six-sided tables, in cylin- ders terminated by two cones, and in double cones with the bases joined. Surface streaked. Lustre shining pearly ; foliated fracture, trans- lucent on the edges ; soft, sectile, and folia usually flexible. Feels rather greasy. Spec, grav. 2.82. It is found at St. Gothard, in Switzerland, and in the island of Java. Its constituents are 35 silica. 18 alumina, 29.1> magnesia, 9.7 oxide of iron, 2-7 water. CHLOROPHANE. A violet Jluor sj>ai\ found in Siberia. CHL 318 CHL CHLORIDES. Compounds of chlorine with bases. See the tespective bases. CHLORIDE OF CARBON. See CAR. BON. CHLORO-CARBONOUS ACID. The tenia chloro-carbonic which has been given to this compound is incorrect, leading to the belief of its being a compound of chlo- rine and acidified charcoal, instead of being a compound of chlorine and the protoxide of charcoal. Chlorine has no immediate action on carbonic oxide, when they are exposed to each other in common day-light over mer- cury; not even when the electric spark is passed through them. Experiments made by Dr. John Davy, in the presence of his brother Sir H. Davy, prove that they combine rapidly when exposed to the direct solar beams, and one volume of each is condensed into one vo- lume of the compound. The resulting gas possesses very curious properties, approaching to those of an acid. From the peculiar po- tency of the sunbeam in effecting this com- bination, Dr. Davy called it plwsgene gas. The constituent gases, dried ove'r muriate of lime, ought to be introduced from separate reservoirs into an exhausted globe, perfectly dry, and exposed for fifteen minutes to bright sunshine, or for twelve hours to day-light. The colour of the chlorine disappears, and on opening the stopcock belonging to the globe under mercury recently boiled, an absorption of one-half the gaseous volume is indicated. The resulting gas possesses properties perfectly distinct from those belonging to either car- bonic oxide or chlorine. It does not fume in the atmosphere. Its odour is different from that of chlorine, some- thing like that which might be imagined to result from the smell of chlorine combined with that of ammonia. It is in fact more in- tolerable and suffocating than chlorine itself, and affects the eyes hi a peculiar manner, producing a rapid flow of tears, and occasion- ing painful sensations. It reddens dry litmus paper, and condenses four volumes of ammonia into a white salt, while heat is evolved. This ammoniacal com- pound is neutral, has no odour, but a pungent saline taste ; is deliquescent, decomposable by the liquid mineral acids, dissolves without ef- fervescing in vinegar, and sublimes unaltered in muriatic, carbonic, and sulphurous acid gases. Sulphuric acid resolves it into carbonic and muriatic acids, in the proportion of two in volume of the latter, and one of the former. Tin, zinc, antimony, and arsenic, heated in chloro-carbonous acid, abstract the chlorine, and leave the carbonic oxide expanded to its original volume. Neither ignition nor ex- plosion takes place, though the action of the metals is rapid. Potassium acting on the compound gas produces a solid chloride and charcoal. White oxide of zinc, with chloro- carbonous acid, gives a metallic chloride, and carbonic acid. Neither sulphur, phos- phorus, oxygen, nor hydrogen, though aided by heat, produces any change on the acid gas. But oxygen and hydrogen together, in due proportions, explode in it ; or mere exposure to water converts it into muriatic and carbonic acid gases. From its completely neutralizing ammonia, which carbonic acid does not ; from its sepa- rating carbonic acid from the subcarbonate of this alkali, while itself it not separable by the acid gases or acetic acid, and its reddening vegetable blues, there can be no hesitation in pronouncing the chloro-carbonous compound to be an acid. Its saturating powers indeed surpass every other substance. None con- denses so large a proportion of ammonia. One measure of alcohol condenses twelve of chloro-carbonous gas without decomposing it ; and acquires the peculiar odour and power of affecting the eyes. To prepare the gas in a pure state, a good air-pump is required, perfectly tight stop-cocks, dry gases, and dry vessels. Its specific gravity may be inferred from the specific gravities of its constituents, of which it is the sum. Hence 2.5 -f- 0.0722 = 3.4722, is the specific gra- vity of chloro-carbonous gas; and 100 cubic- inches weigh 105.9 grains. It appears that when hydrogen, carbonic oxide, and chlo- rine, mixed in equal volumes, are exposed to light, muriatic and chloro-carbonous acids are formed, in equal proportions, indicating an equality of affinity. The paper in the Phil. Trans, for 1812, from which the preceding facts are taken, does honour to the school of Sir H. Davy. MM. Gay Lussac and Thenard, as well as Dr. Murray, made controversial investigations on the subject at the same time, but without success. M. Thenard has, however, recog- nized its distinct existence and properties, by the name of carlo-muriatic acid, in the 2d volume of his System, published in 1814, where he considers it as a compound of mu- riatic and carbonic acids, resulting from the mutual actions of the oxygenated muriatic add and carbonic oxide. CHLOROPAL. A mineral of which there are two varieties, theconchoidal, and the earthy. The conchoidal has a pistachio green colour, opaque, specific gravity 2. It breaks readily into parallelepipeds. It consists of silica 46 ; oxide of iron 35.3 ; magnesia 2 ; alumina 1.0; water 18; with traces of potash and manganese. It is found accompanying copal, not far from Unghwar in the comitate of the same name. CHLOROPHCEITE. A mineral of a green colour when newly broken, but soon be- coming black. It is scratched by a quill. Brittle. Sp. grav. 2.02. Not affected by the blowpipe. It is found imbedded in the umyg- daloids of the cliff of Scuirmore, in the isle of Rum, and also in Fife, in nodules generally CHL 319 CHL round, from the size of a radish seed, to that of a pea. Dr. Maccuttoch. CHLOROUS and CHLORIC OXIDES, or the protoxide and deutoxide of chlorine. Both of these interesting gaseous compounds were discovered by Sir H. Davy. 1st, The experiments which led him to the knowledge of the first were instituted in con- sequence of the difference he had observed between the properties of chlorine, prepared in different modes. The paper describing the production and properties of the chlorous oxide was published in the first part of the Phil. Trans, for 181 1. To prepare it, we put chlorate of potash into a small retort, and pour in twice as much muriatic acid as will cover it, diluted with an equal volume of water. By the ap- plication of a gentle heat, the gas is evolved. It must be collected over mercury. Its tint is much more lively, and more yellow than chlorine, and hence its illustrious discoverer named it euchlorine. Its smell is peculiar, and approaches to that of burnt sugar. It is not respirable. It is soluble in water, to which it gives a lemon colour. Water absorbs 8 or 10 times its volume of this gas. Its spe- cific gravity is to that of common air nearly as 2.40 to 1 ; for 100 cubic inches weigh, ac- cording to Sir H. Davy, between 74 and 75 grains. If the compound gas result from 4 volumes of chlorine -f- 2 of oxygen, weighing 12.1154, which undergo a condensation of one- sixth, then the specific gravity comes out 2.423, in accordance with Sir H. Davy's experiments. He found that 50 measures detonated in a glass tube over pure mercury, lost their brilliant colour, and became 60 measures, of which 40 were chlorine and 20 oxygen. This gas must be collected and examined with much prudence, and in very small quan- tities. A gentle heat, even that of the hand, will cause its explosion, with such force as to burst thin glass. From this facility of de- composition, it is not easy to ascertain the action of combustible bodies upon it. None of the metals that burn in chlorine act upon this gas at common temperatures ; but when the oxygen is separated, they then inflame in the chlorine. This may be readily exhibited, by first introducing into the protoxide a little Dutch foil, which will not be even tarnished ; but on applying a heated glass tube to the gas in the neck of the bottle, decomposition in- stantly takes place, and the foil burns with brilliancy. When already in chemical union, therefore, chlorine has a stronger attraction for oxygen than for metals ; but when insulated, its affinity for the latter is predominant. Prot- oxide of chlorine has no action on mercury, but chlorine is rapidly condensed by this metal into calomel. Thus the two gases may be completely separated. When phosphorus is introduced into the protoxide, it instantly burns, as it would do in a mixture of two vo- lumes of chlorine and one of oxygen ; and a chloride and acid of phosphorus result. Lighted taper and burning sulphur likewise instantly decompose it. When the protoxide freed from water is made to act on dry vegetable colours, it gradually destroys them, but first gives to the blues a tint of red ; from which, from its absorbability by water, and the strongly acrid taste of the solution approaching to sour, it may be considered as approximating to an acid in its nature. Since 2 volumes of chlorine weigh (2 X 2.5) 5, and 1 of oxygen 1.1111 ; we have 4.5 -f- 1 r^ 5.5 for the prime equi- valent of chlorous oxide on the oxygen scale. The proportion by weight in 100 parts is 81.65 chlorine + 18-35 oxygen. 2d, Deutoxide of Chlorine, or Chloric Oxide. " On Thursday the 4th May, a paper by Sir H. Davy was read at the Royal So- ciety, on the action of acids on hyper-oxy- muriate of potash. When sulphuric acid is poured upon this salt in a wine-glass, very little effervescence takes place, but the acid gradually acquires an orange colour, and a dense yellow vapour, of a peculiar and not disagreeable smell, floats on the surface. These phenomena led the author to believe, that the substance extricated from the salt is held ia solution by the acid. After various unsuccessful attempts to obtain this substance in a separate state, he at last succeeded by the following method : About 60 grains of the salt are triturated with a little sulphuric acid, just sufficient to convert them into a very solid paste. This is put into a retort, which is heated by means of hot water. The water must never be allowed to become bailing hot, for fear of explosion. The heat drives off the new gas, which may be received over mercury. This new gas has a much more intense colour than euchlorine. It does not act on mercury. Water absorbs more of it than of euchlorine. Its taste is astringent. It destroys vegetable blues without reddening them. When phos- phorus is introduced into it, an explosion takes place. When heat is applied, the gas explodes with more violence, and producing more light than euchlorine. When thus exploded, two measures of it are converted into nearly three measures, which consist of a mixture of one measure chlorine, and two measures oxygen. Hence, it is com- posed of one atom chlorine and four atoms oxygen." Deutoxide of chlorine has a peculiar aro- matic odour, unmixed with any smell of chlorine. A little chlorine is always ab- sorbed by the mercury during the explosion of the gas. Hence the small deficiency of the resulting measure is accounted for. At com- mon temperatures none of the simple combus- tibles which Sir H. Davy tried, decompose the gas, except phosphorus. The taste of the aqueous solution is extremely astringent and corroding, leaving for a long while a very dis- agreeable sensation. The action of liquid CHO 320 CHR nitric acid on the chlorate of potash affords the same gas, and a much larger quantity of this acid may be safely employed than of the sulphuric. But as the gas must be procured by solution of the salt, it is always mixed with about one-fifth of oxygen. Since two measures of this gas, at 212, explode and form three measures of mingled gases, of which two are oxygen and one chlo- rine ; its composition by weight is Oxygen, 2.2222 Chlorine, 2.5 4 primes, 4.00 47 1 do. 4.5 53 8.5 100 Its specific gravity is 2.361 ; and hence 100 cubic inches of it weigh about 77 grains. CHLOROPHILE. The name lately given by MM. Pelletier and Caventou to the green matter of the leaves of plants. They obtained it by pressing, and then washing in water, the substance of many leaves, and after- wards treating it with alcohol. A matter was dissolved, which, when separated by evapora- tion, and purified by washing in hot water, appeared as a deep green resinous substance. It dissolves entirely in alcohol, ether, oils, or alkalis ; it is not altered by exposure to air : it is softened by heat, but does .not melt ; it burns with flame, and leaves a bulky coal. Hot water slightly dissolves it. Acetic acid is the only acid that dissolves it in great quan- tity. If an earthy or metallic salt be mixed with the alcoholic solution, and then alkali or alkaline subcarbonate be added, the oxide or earth is thrown down in combination with much of the green substance, forming a lake. These lakes appear moderately permanent when exposed to the air. It is supposed to be a peculiar proxiaiate principle. The above learned term should be spelled with a ?/, chlorophyle, to signify the green of leaf, or leaf-green : chlorophile, with an z, has a different etymology, and a different meaning. It signifies fond of green. CHOLESTERINE. The name given by M. Chevreul to the pearly substance of human biliary calculi. It consists of 72 carbon, 6.CG oxygen, and 21.33 hydrogen, by Berard. M. Chevreul has lately extracted choleste- rine from human bile. The bile, after being diluted, filtered, and concentrated, was preci- pitated by alcohol ; the alcoholic extract was acted upon by ether, and the latter solution left to crystallize spontaneously ; a substance separated, which, when purified, was neither acid nor alkaline to vegetable colours, which like cholesterine crystallized, either when fused and cooled, or when dissolved in alcohol or ether. It required about 212 for its fusion, was not saponified by being boiled for 24 hours in solution of potash ; in contact with vsulphuric acid, it instantly became of an orange- red colour, and witli nitric acid comported it- self like cholesterine. The same substance was also obtained by him from the bile of a bear and a pig. CHOLESTERIC ACID. See ACID (CHOLESTERIC). CHROMIUM. This metal may be ex- tracted either from the native chromate of lead or of iron. The latter being cheapest and most abundant, is usually employed. The brown chromite of iron is not acted upon by nitric acid, but most readily by nitrate of potash, with the aid of a red heat. A chro- mate of potash, soluble in water, is thus formed. The iron oxide thrown out of combination may be removed from the residual part of the ore by a short digestion in dilute muriatic acid. A second fusion with \ of nitre, will give rise to a new portion of chromate of potash. Hav- ing decomposed the whole of the ore, we sa- turate the alkaline excess with nitric acid, eva- porate and crystallize. The pure crystals, dissolved in water, are to be added to a solu- tion of neutral nitrate of mercury ; whence, by complex affinity, red chromate of mercury precipitates. Moderate ignition expels the mercury from the chromate, and the remaining chromic acid may be reduced to the metallic state, by being exposed in contact of the char- coal from sugar, to a violent heat. Chromium thus procured is a porous mass of agglutinated grains. It is very brittle, and of a greyish- white, intermediate between tin and steel. It is sometimes obtained in needleform crystals, which cross each other in all direc- tions. Its sp. gravity is 5.9. It is susceptible of a feeble magnetism. It resists all the acids except nitromuriatic, which, at a boiling heat, oxidizes it and forms a muriate. M. Thenard describes only one oxide cf chromium ; but there are probably two, besides the acid already described. 1. The protoxide is green, infusible, inde- composable by heat, reducible by voltaic elec- tricity, and not acted on by oxygen or air. When heated to dull redness with the half of its weight of potassium or sodium, it forms a brown matter, which, cooled and exposed to the air, burns with flame, and is transformed into chromate of potash or soda, of a canary- yellow colour. It is this oxide which is ob- tained by calcining the chromate of mercury in a small earthen retort for about f of an hour. Tiie beak of the retort is to be surrounded with a tube of wet linen, and plunged into water, to facilitate the condensation of the mercury. The oxide, newly precipitated from acids, has a dark green colour, and is easily redissolved ; but exposure to a dull red heat ignites it, and renders it denser, insoluble, and of a light green colour. This change arises solely from the closer aggregation of the particles, for the weight is not altered. 2. The dcutoxide is procured by exposing the protonitrate to heat, till the fumes of ni- trous gas cease to issue. A brilliant brown CHR 321 powder, insoluble in acids, and scarcely solu- ble in alkalis, remains. Muriatic acid digested on it exhales chlorine, showing the increased proportion of oxygen in this oxide. 3. The tritoxide has been already described among the acids. It may be directly procured, by adding nitrate of lead to the above nitro- chromate of potash, and digesting the beautiful orange precipitate of chromate of lead with moderately strong muriatic acid, till its power of action be exhausted. The fluid produced is to be passed through a filter, and a little oxide of silver very gradually added, till the whole solution becomes of a deep red tint. This liquor, by slow evaporation, deposits small ruby-red crystals, which are the hy- drated chromic acid. The prime equivalent of chromic acid deduced from the chromates of barytes and lead by Berzelius, is 6.544, if we suppose them to be neutral salts. According to this chemist, the acid contains double the oxygen that the green oxide does. But if these chromates be regarded as subsalts, then the acid prime would be 13.088, consisting of 6 oxygen -}- 7-088 metal ; while the protoxide would consist of 3 oxygen + 7-088 metal ; and the deutoxide of an intermediate propor- tion. M. Unverdorben states that if chromate of lead be distilled with common salt, and anhy- drous sulphuric acid, a reddish gas is obtained, consisting of chromium combined with chlo- rine. Water converts it into chromic and muriatic acids. By passing the above gas through a cold tube, the chloride of chromium is entirely condensed, while the chlorine and muriatic acid evolved along with it pass off. The liquid chloride is of a fine blood red co- lour, heavier than water, very volatile, fuming in the air, and then of a colour analogous to that of nitrous acid when in vapour. It ra- pidly attacks mercury, acts on sulphur with much energy, and a hissing noise ; it deto- nates with phosphorus, even when the particles of each do not exceed the size of a pin's head. Journ. of Science, xxii. 211. CHRYSOBERYL. Cymopliane of Haiiy. This mineral is usually got in round pieces about the size of a pea, but it is found crys- tallized in eight-sided prisms, terminated by six-sided summits. Colour, asparagus green ; lustre, vitreous ; fracture, conchoidal ; it is semitransparent and brittle, but scratches quartz and beryl. Sp. gr. 3.76. It is infu- sible before the blowpipe. It has double re- fraction, and becomes electric by friction. Its primitive form is a rectangular parallelepiped. Its constituents, according to Klaproth, are 71 alumina, 18 silica, 6 lime, 1^ oxide of iron. The summits of the prisms of chrysoberyl are sometimes so cut into facettes that the solid acquires 28 faces. It is found at Brazil, Ceylon, Connecticut, and perhaps Nertschink in Siberia. This mineral has nothing to do with the chrysoberyl of Pliny, which was pro- bably a variety of beryl of a greenish-yellow colour. CHRYSOCOLLA. The Greek name for borax. CHRYSOLITE. Pcrufctf of Hatty. To- paz of the ancients, while our topaz is their chrysolite. Chrysolite is the least hard of all the gems. It is scratched by quartz and the file. Its crystals are well formed compressed prisms, of eight sides at least, terminated by a wedged form or pyramidal summit, trun- cated at the apex. Its primitive form is a right prism, with a rectangular base. It has a strong double refraction, which is observed in looking across one of the large sides of the summit and the opposite face of the prism. The lateral planes are longitudinally streaked. The colour is pistachio green, and other shades. External lustre splendent. Transparent ; frac. ture, conchoidal. Scratches felspar. Brittle. Sp. gr. 3.4. With borax, it fuses into a pale green glass. Its constituents are 39 silica, 43-5 magnesia, 19 of oxide of iron, according to Klaproth ; but Vauquelin found 38, 50-5, and 9.5. Chrysolite comes from Egypt, where it is found in alluvial strata. It has also been found in Bohemia, and in the Circle of Bun- zlau. CHRYSOPRASE. A variety of calce- dony. It is either of an apple or leek-green colour. Its fracture is even, waxy, sometimes a little splintery. Translucent, with scarcely any lustre. Softer than calcedony, and rather tough. Sp. gr. 2.5. A strong heat whitens it. It consists of 96.16 silica, 0.08 alumina, 0.83 lime, 0.08 oxide of iron, and 1 oxide of nickel, to which it probably owes its colour. It has been found hitherto only at Kosemiitz in Upper Silesia. The mountains which en- close it are composed chiefly of serpentine, potstone, talc, and other unctuous rocks that almost all contain magnesia. It is found in veins or Interrupted beds in the midst of a green earth which contains nickel. It is used in jewellery. CHUSITE. A mineral found by Saussure in the cavities of porphyries in the environs of Limbourg. It is yellowish or greenish and translucent ; its fracture is sometimes perfectly smooth, and its lustre greasy ; at other times it is granular. It is very brittle. It melts easily into a translucid enamel, enclosing air bubbles. It dissolves entirely, and without effervescence, in acids. CHYAZIC. See ACID (FERROPRUS- sic). CHYLE. By the digestive process in the stomach of animals, the food is converted into a milky flujd, called chyme, which passing into the intestine, is mixed with pancreatic juice and bile, and thereafter resolved into chyle and feculent matter. The former is taken up by the lacteal absorbent vessels of the intes- tines, which coursing along the mesenterk CIM 322 CIN web, terminate in the thoracic duct. This finally empties its contents into the vena cava. Chyle taken soon after the death of an animal, from the thoracic duct, resembles milk in appearance. It has no smell, but a slightly acido-saccharine taste; yet it blues reddened litmus paper by its unsaturated alkali. Soon after it is drawn from the duct, it sepa- rates by coagulation into a thicker and thinner matter. 1 . The former, or curd, seems inter- mediate between albumen and fibrin. Potash and soda dissolve it with a slight exhalation of ammonia. Water of ammonia forms with it a reddish solution. Dilute sulphuric acid dis- solves the coagulum ; and very weak nitric acid changes it into adipocere. By heat, it is converted into a charcoal of difficult incinera- tion, which contains common salt and phos- phate of lime, with minute traces of iron. 2. From the serous portion, heat, alcohol, and acids, precipitate a copious coagulum of albu- men. If the alcohol be hot, a little matter ana- logous to the substance of brain is subsequent- ly deposited. By evaporation and cooling, Mr. Brande obtained crystals analogous to the sugar of milk. Dr. Marcet found the chyle of graminivorous animals thinner and darker, and less charged with albumen, than that of carni- vorous. In the former, the weight of the fluid part to that of the coagulum was nearly 2 to 1 ; but a serous matter afterwards oozed out, which reduced the clot to a very small volume. CHYME. Dr. Marcet examined chyme from the stomach of a turkey. It was a ho- mogeneous, brownish opaque pulp, having the smell peculiar to poultry. It was neither acid nor alkaline, and left one-fifth of solid matter by evaporation. It contained albumen. From the incineration of 1000 parts, 12 parts of charcoal resulted, in which iron, lime, and an alkaline muriate were distinguished. See DIGESTION. CIMOLITE, or CIMOLIAN EARTH. The cimol'ta of Pliny, which was used both medicinally and for cleaning cloths by the ancients, and which has been confounded with fullers' earth and tobacco-pipe clay, has lately been brought from Argentiera, the ancient Cimolus, by Mr. Hawkins, and examined by Klaproth. It is of a light greyish- white colour, ac- quiring superficially a reddish tint by exposure to the air; massive; of an earthy, uneven, more or less slaty fracture; opaque; when shaved with a knife, smooth and of a greasy lustre ; tenacious, so as not without difficulty to be powdered or broken ; and adhering pretty firmly to the tongue. Its specific gravity is 2. It is immediately penetrated by water, and dev^lopes itself into thin laminae of a curved slaty form. Triturated with water it forms a pappy mass; and 100 grains will give three ounces of water the appearance and consistence 4f a thickish cream. If left to dry after being thus ground, it detaches itself in hard bands, somewhat flexible, and still more difficult to pulverize than before. It appeared on analysis to consist of silex 63, alumina 23, oxide of iron 1.25, water 12. Ground with water, and applied to silk and woollen, greased with oil of almods, the oil was completely discharged by a slight washing in water, after the stuffs had been hung up a day to dry, without the least injury to the beauty of the colour. Mr. Klaproth considers it as superior to our best fullers' earth ; and attributes its properties to the minutely divided state of the silex, and its intimate combina- tion with the alumina. It is still used by the natives of Argentiera for the same purposes as of old. According to Olivier the island of Argen- tiera is entirely volcanic, and the Cimolian earth is produced by a slow and gradual de- composition of the porphyries, occasioned by subterranean fires. He adds, that he collected specimens of it in all the states through which it passes. CINCHONA. The quinquina and kina of the French, is the bark of several species of cinchona, which grow in South America. Of this bark there are three varieties, the red, the yellow, and the pale. I. The red is in large, easily pulverized pieces, which furnish a reddish-brown powder, having a bitter astringent taste. The watery infusion reddens vegetable blues, from some free citric acid. It contains also muriates of ammonia and lime. The bark contains ex- tractive, resin, bitter principle, and tannin. 2. The yellow Peruvian bark was first brought to this country about the year 1790 ; and it resembles pretty closely in composition the red species, only it yields a good deal of kin ate of lime in plates. 3. The pale cinchona is that generally employed in medical practice, as a tonic and febrifuge. M. Vauquelin made infusions of all the varieties of cinchona he could procure, using the same quantities of the barks and water, and leaving the powders infused for the same time. He observed, 1. That certain infusions were precipitated abundantly by infusion of galls, by solution of glue, and tartar emetic. 2. That some were precipitated by glue, but not by the two other re-agents ; and 3. That others were, on the contrary, by nutgalls and tartar emetic, with- out being affected by glue. 4. And that there were some which yielded no precipitate by nutgalls, tannin, or emetic tartar. The cinchonas that furnished the first infusion were of excellent quality ; those that afforded tha fourth were not febrifuge ; while those that gave the second and third were febrifuge, but in a smaller degree than the first. Besides raucilage, kinate of lime, and woody fibre, he obtained in his analyses a resinous substance, which appears not to be identic in all the spe- cies of bark. It is very bitter; very soluble CIN 323 CIN in alcohol, in acids, and alkalis ; scarcely so- luble in cold water, but more soluble in hot. It is this body which gives to infusions of cinchona the property of yielding precipitates by emetic tartar, galls, gelatin ; and in it, the febrifuge virtue seems to reside. It is this substance in part which falls down on cooling decoctions of cinchona, and from concentrated infusions. A table of precipitations by glue, tannin, and tartar emetic, from infusions of different barks, has been given by M. Vau- quelin ; but as the particular species are diffi- cult to define, we shall not copy it. Analysis of the cinchona condamincea (grey bark) by MM. Pelletier and Caventou. They found it composed of, 1. cinchonina, united to kinic acid ; 2. green fatty matter ; 3. red colouring matter, slightly soluble ; 4. tannin ; 5. yellow colouring matter; 6. kinate of lime ; 7- guni ; 8. starch ; 9. lignine. CINCHONINA. A salifiable base, or vegetable alkali, discovered in cinchona con- damincea, by MM. Pelletier and Caventou. The person, however, who first recognized its existence, though he did not ascertain its alkaline nature, or study its combinations with acids, wasM. Gornis of Lisbon. Mr. Brande prescribes the following process for separating cinchonina from Peruvian bark, (cinchona lancifolia). A pound of bruised bark is boiled in about a gallon of water, to which three fluid drachms of sulphuric acid have been previously added. A similar de- coction is repeated with about half the quantity of liquid, and so on till all the soluble matter is extracted. The decoctions are then mixed together, and strained ; and powdered slaked lime is added in a proportion, somewhat greater than necessary to saturate the acid ; the precipitate that ensues (a mixture of cinchonina and sulphate of lime) is collected, dried, and boiled for some minutes in strong alcohol, which is then decanted off while still hot, and fresh portions successively added for the repetition of the same operation, until it ceases to act on the residuum, which is then merely sulphate of lime. The different alcoholic solutions are then put into a retort or still, and considerably evaporated, during which, and especially on cooling, acicular crystals of cinchonina are deposited. When the whole is thus collected, the crystals, if yellow or dis- coloured, must be again dissolved in boiling alcohol, and thus, by re-crystallization, they will be obtained colourless. Manual of Phar- macy, p. 61. The following process for extracting cin- chonina is that of M. Henry fils, which the above French chemists approve of. A kilo- gramme of bark reduced into a pretty fine powder is to be acted on twice with heat, by a dilute sulphuric acid, consisting of 50 or 60 grammes, diluted with 8 kilogrammes of water for each time. The filtered decoctions are very bitter, have a reddish colour, which assumes on cooling a yellowish tint. To discolour (blanch) these liquors, and saturate the acid, either pulverized quicklime or magnesia may be employed. The liquors, entirely deprived of colour, are to be passed through a cloth, and the precipitate which forms is to be washed with a small quantity of water, to separate the excess of lime (if this earth has been used). The deposit on the cloth, well drained and almost completely deprived of moisture for 12 hours, after having been put three successive times to digest in alcohol of 36 (0-837), will furnish, by distilling of the liquid alcohol, a brown viscid matter, becoming brittle on cooling. It is to be acted on with water sharpened with sulphuric acid, and the re- frigerated liquor will afford about 30 grammes of white crystals, entirely soluble in alcohol, scarcely soluble in cold water, but more in boiling water, particularly if this be slightly acidulated. They consist of pure sulphate of cinchonina. They ought to be brilliant, crys- tallized in parallelopideds, very hard, and of a glassy white. It should burn, withoutleaving any residuum. Other processes have been given, of which a full account will be found in the 12th volume of the Journal of Science, p. 325. From a solution of the above salt, the cinchonina may be easily obtained by the addition of any alkali. The cinchonina falls down, and may be afterwards dissolved in alcohol, and crystallized by evaporation. Its form is arhomboidal prism, of 108 and 72, terminated by a bevelment. It has but little taste, requiring 7000 parts of water for its solution ; but when dissolved in alcohol, or an acid, it has the bitter taste of bark. When heated, it -does not fuse before decomposition. According to Mr. Brande, cinchonina con- sists of Carbon 80-20 Azote 12-85 Hydrogen 6-85 99-90 By another experiment, he found its consti- tuents to be Carbon - 78-4 Azote * 14-6 Hydrogen 7-5 100-5 He could detect no trace of oxygen in it. Journal of Science, xvi. 282. MM. Dumas and Pelletier, in an elaborate memoir on the ultimate analysis of vegeta- bles, represent cinchonina as consisting of Carbon . 76.97 Azote 9-02 Hydrogen - - 622 Oxygen . - 7-97 10018 Y2 CIS 324 CLA It dissolves in only very small quantities in the oils, and in sulphuric ether. The sulphate is composed of cinchonina, 100 Sulphuric acid, 13 whence the prime equivalent would appear to be 38-5. The muriate is more soluble. It consists of Cinchonina -100 Muriatic acid 7-9 The nitrate is uncrystallizable. Gallic, oxalic, and tartaric acids, form neutral salts with cinchonina, which are soluble only with ex- cess of acid. Hence infusion of nut-galls gives, with a decoction of good cinchona, an abundant precipitate of gallate of cin- chonina. M. Baup states the composition of crys- tallized neutral sulphate of cinchonina to be 1 atom cinchonina 39 84-324 1 sulphuric acid 5 10-811 2 water 2-25 4-865 46-25 100-000 Supersulphate of cinchonina, he says, contains 2 atoms of acid, and 9 of water. The latter appears in imperfect rhomboidal octohedra ; the former in rhomboidal prisms. Ann. de Chim. et de Phys. xxvii. 323. M. Robiquet gives as the composition of a subsulphate of cinchonina of the first crys- tallization, Sulphuric acid ''.' 11-3 Cinchonina 79-0 The alkaline base found in yellow barks is called QUININA. It is extracted in exactly the same way. Red bark contains a mixture of these two alkalis. The febrifuge virtue of the sulphates is considered to be very great. See Q.UININA. CINNABAR. An ore of mercury, con- sisting of that metal united with sulphur. CINNAMON STONE. The colours of this rare mineral are blood-red, and hyacinth- red, passing into orange-yellow. It is found always in roundish pieces ; lustre splendent ; fracture imperfect conchoidal ; fragments an- gular ; transparent and semi-transparent ; scratches quartz with difficulty; somewhat brittle ; sp. gr. 3-53 ; fuses into a brownish- black enamel. Its constituents are 38-8 silica, 21 -3 alumina, 31-25 lime, and 6-5 oxide of iron. It is found in the sand of rivers in Ceylon. CIPOLIN. The Cipolin from Rome is a green marble with white zones ; it gives fire with steel, though difficultly. One hundred parts of it contain 67-8 of carbonate of lime; 25 of quartz ; 8 of schistus ; 0-2 of iron, be- side the iron contained in the schistus. The cipolin from Autun, 83 parts carbonate of lime, 12 of green mica, and one of iron. CIST 1C OXIDE. A peculiar animal product, discovered by Dr. Wollaston. It constitutes a variety of urinary CALCULUS, which see. CITRIC ACID. Acid of limes. It has been found nearly unmixed, with other acids, not only in lemons, oranges, and limes, but also in the berries of vaccinium oxycoccos^ or cranberry, vaccininm vitis idcea, or red- whortleberry, of birdcherry, nightshade, hip, in unripe grapes and tamarinds. Gooseberries, currants, "bilberries, beamberries, cherries, strawberries, cloudberries, and raspberries, contain citric acid mixed with an equal quan- tity of mallic acid. The onion yields citrate of lime. See ACID (CiTUic). CITRATES. Salts formed by CITRIC ACID, which see. CIVET is collected betwixt the anus and the organs of generation of a fierce carnivorous quadruped met with in China and the East and West Indies, called a civet-cat, but bear- ing a greater resemblance to a fox or marten than a cat. Several of these animals have been brought into Holland, and afford a considerable branch of commerce, particularly at Amsterdam. The civet is squeezed out, in summer every other day, in winter twice a-week : the quantity procured at once is from two scruples to a drachm or more. The juice thus collected is much purer and finer than that which the animal sheds against shrubs or stones in its native climates. Good civet is of a clear yellowish or brownish colour, not fluid, nor hard, but about the con- sistence of butter or honey, and uniform throughout ; of a very strong smell ; quite offensive when undiluted ; but agreeable when only a small portion of civet is mixed with a large one of other substances. Civet unites with oils, but not with alcohol. Its nature is therefore not resinous. M. Boutron-Charlard states, that in an un- exceptionably good civet, semi-fluid, unctuous, and yellow, he found free ammonia, stearine, elai'ne, mucus, resin, volatile oil, yellow co- louring substance, and salts. No benzoic acid could be detected in it. Journ. de Pharmacie for 1824, p. 537. CLARIFICATION is the process of free- ing a fluid from heterogeneous matter or fecu- lencies, though the term is seldom applied to the mere mechanical process of straining, for which see FILTRATION. Albumen, gelatine, acids, certain salts, lime, blood, and alcohol, in many cases serve to clarify fluids that cannot be freed from their impurities by simple percolation. Albumen or gelatine, dissolved in a small portion of water, is commonly used for fining vinous liquors, as it inviscates the feculent matter, and gradually subsides with it to the bottom. Albumen is particularly used for fluids, with which it will combine when cold, CLA 325 CLA as syrups ; it being coagulated by the heat, and then rising in a scum with the dregs. Heat alone clarifies some fluids, as the juices of plants, in which however the albu- men they contain is probably the agent. A couple of handfuls of marie, thrown into the press, will clarify cyder, or water-cyder. CLAY (PURE). See ALUMINA. CLAY. The clays being opaque and non- crystallized bodies, of dull fracture, afford no good principle for determining their species ; yet as they are extensively distributed in nature, and are used in many arts, they deserve particular attention. The argillaceous minerals are all sufficiently soft to be scratched by iron ; they have a dull or even earthy fracture; they exhale, when breathed on, a peculiar smell called argillaceous. The clays form with water a plastic paste, possessing considerable tenacity, which hardens with heat, so as to strike fire with steel. Maries and chalks also soften in water, but their paste is not tenacious, nor does it acquire a siliceous hardness in the fire. The affinity of the clays for moisture is manifested by their sticking to the tongue, and by the intense heat necessary to make them perfectly dry. The odour ascribed to clays breathed upon, is due to the oxide of iron mixed with them. Absolutely pure clays emit no smell. 1. Porcelain earth, the kaolin of the Chi- nese. This mineral is friable, meagre to the touch, and, when pure, forms with difficulty a paste with water. It is infusible in a porce- lain furnace. It is of a pure white, verging sometimes upon the yellow or flesh-red. Some present particles of mica, which betray their origin to be from felspar or graphic granite. It scarcely adheres to the tongue. Sp. gr. 2.2. It is found in primitive mountains, amid blocks of granite, forming interposed strata. Kaolins are sometimes preceded by beds of a micaceous rock of the texture of gneiss, but red and very friable. This re- markable disposition has been observed in the Kaolin quarries of China, in those $f Alen9on, and of Saint Yriex near Limoges. The con- stituents of kaolin are 52 silica, 47 alumina, 0.33 oxide of iron ; but some contain a nota- ble proportion of water in their recent state. The Chinese and Japanese kaolins are whiter and more unctuous to the touch than those of Europe. The Saxon has a slight tint of yellow or carnation, which disappears in the fire, and therefore is not owing to metallic impregnation. At Saint Yriex the kaolin is in a stratum and also in a vein, amid blocks of granite, or rather the felspar rock, which the Chinese call petuntze. The Cornish kaolin is very white and unctuous to the touch, and obviously is formed by the disin- tegration of the felspar of granite. 2. Potters' clay, or plastic day The clays of this variety are compact, smooth, and almost unctuous to the touch, and may be polished by the finger when they are dry. They have a great affinity for water, form a tenacious paste, and adhere strongly to the tongue. The paste of some is even slightly transparent. They acquire great solidity, but are infusible in the porcelain furnace. This property distinguishes them from common clays, employed for coarse earthen- ware. Some of them remain white, or become so in a high heat ; others turn red. Sp. gr. 2. The slaty potters' clay of Werner has a dark ash-grey colour ; principal fracture imperfectly con- choidal, cross fracture earthy ; fragments tabu- lar, rather light, and feels more greasy than common potters' clay. Vauquelin's analysis of the plastic clay of Forges-les-Eaux, em- ployed for making glass-house pots, as well as pottery, gave 16 alumina, 63 silica, 1 lime, 8 iron, and 10 water. Another potters' clay gave 33.2 and 43.5 of alumina and silica, with 3.5 lime. 3. Loam. This is an impure potters' clay mixed with mica and iron ochre. Colour yellowish-grey,, often spotted yellow and brown. Massive, with a dull glimmering lustre from scales of mica. Adheres pretty strongly to the tongue, and feels slightly greasy. Its density is infeiior to the preceding. 4. Variegated clay. Is striped or spotted with white, red, or yellow colours. Massive, with an earthy fracture, verging on slaty. Shining streak. Very soft, sometimes even friable. Feels slightly greasy, and adheres a little to the tongue. Sectile. It is found in Upper Lusatia. 5. Slate clay. Colour grey, or greyish- yellow. Massive. Dull or glimmering lustre, from interspersed mica. Slaty fracture, ap- proaching sometimes to earthy. Fragments tabular. Opaque, soft, sectile, and easily broken. Sp. gr. 2.6. Adheres to the tongue, and breaks down in water. It is found along with coal, and in the floetz trap formation. 6. Claystone. Colour grey, of various shades, sometimes red, and spotted or striped. Massive. Dull lustre, with a fine earthy frac- ture, passing into fine grained uneven, slaty, or splintery. Opaque, soft, and easily broken. Does not adhere to the tongue, and is meagre to the touch. It has been found on the top of the Pentland hills in Scotland, and in Germany. 7. Adhesive slate. Colour light greenish- grey. Internal lustre dull; fracture in the large, slaty ; in the small, fine earthy. Frag- ments slaty. Opaque. Shining streak. Sectile. Easily broken or exfoliated. Adheres strongly to the tongue, and absorbs water rapidly with the emission of air bubbles, and a crackling sound. It is found at Montmartre near Paris, between blocks of impure gypsum, in large straight plates like sheets of pasteboard. It is found also at Menilmontant, enclosing menilite. Klaproth's analysis is 62.5 silica, 8 magnesia, 0.5 alumina, 0.25 lime, 4 oxide CLE 326 CLI of iron, 22 water, and 0-75 charcoal. Its sp. gr. is 2.08. 8. Polishing slate of Werner Colour, cream-yellow, in alternate stripes. Massive. Lustre dull. Slaty fracture. Fragments ta- bular. Very soft, and adheres to the tongue. Smooth, but meagre to the touch. Sp. gr. in its dry state 0.0 ; when imbued with mois- ture 1.9. It has been found only in Bohemia. Its constituents are 79 silica, 1 alumina, 1 lime, 4 oxide of iron, and 14 water. 9. Common day may be considered to be the same as loam. Besides the above, we have the analysis of some pure clays, the re- sults or which show a very minute quantity of silica, and a large quantity of sulphuric acid. Thus, in one analyzed by Bucholz, there was 1 silica, 31 alumina, 0.5 lime, 0.5 oxide of iron, 21.5 sulphuric acid, 45 water, and 0.5 loss. Simon found 19.35 sulphuric acid in 100 parts. We must regard these clays as subsulphates of alumina. CLAY-SLATE. Argillaceous schistus, the Argillite of Kirwan. Colour, bluish-grey, and greyish-black of various shades. Massive. Internal lustre shining or pearly. Fracture foliated. Fragments tabular. Streak, green- ish-white. Opaque. Soft. Ssctile. Easily broken. Sonorous, when struck with a hard body. Sp. gr. 2-7- Its constituents are 48.6 silica, 23.5 alumina, 1.6 magnesia, 11.3 per- oxide of iron, 0-5 oxide of manganese, 4.7 potash, 0.3 carbon, O.I sulphur, 7-6 water and volatile matter. Clay-slate melts easily by the blowpipe into a shining scoria. This mineral is extensively distributed, forming a part of both primitive and transition moun- tains. The great beds of it are often cut across by thin seams of quartz or carbonate of lime, which divide them into rhomboidal masses. Good slates should not imbibe water. If they do, they soon decompose by the weather. CLAY IRON-STONE. See ORES OF IRON. CLEAVAGE OF CRYSTALS. The mechanical division of crystals, by showing the direction in which their lamina; can sepa- rate, enables us to determine the mutual inclination of these laminae : Werner called it durchgang, but he attended only to the num- ber of directions in which this mechanical division of the plates, or cleavage, could be effected. In the interior of many minerals, the direction of the cleavage may be frequently seen, without using any mechanical violence. CLEAVLANDITE. A mineral formerly ranked among felspars; but they differ in this, that die 13 or 14 per cent, of potash in felspar, is replaced by about 10 per cent, of soda in the cleavlandite, which moreover is not so hard as felspar. Mr. Levy considers the primitive form of felspar to be an oblique rhombic prism ; and that of cleavlandite a .doubly oblique prism. The crystals of the latter have a certain brilliancy which does not belong to the former. The localities of cleavlandite are very numerous; but the finest crystals come from the Tyrol and St. Gothard. The largest from Siberia, where they are met upon the same specimen with large crystals of reddish felspar and smoky quartz. The most transparent come from Dauphiny. This mineral is generally white, but is also found bluish and blue, and of a dingy red. It is sometimes regularly lami- nated, affording distinct cleavages parallel to all the planes of a doubly oblique prism, yielding by the reflective goniometer, in one direction, alternate measurements of 93 30', and 86 30'; in another of 119 30', and 60 30'; and in the third of 115 and 65. It was at first called albite and siliceous felspar. It consists of silica 70.7, alumina 19-8, soda 9, lime 0.2, oxide of manganese 0.1. Stromeyer. CLIMATE. The prevailing constitution of the atmosphere, relative to heat, wind, and moisture, peculiar to any region. This de- pends chiefly on the latitude of the place, its elevation above the level of the sea, and its insular or continental position. Springs which issue from a considerable depth, and caves about 50 feet under the surface, preserve an uniform temperature through all the vicissi- tudes of the season. This is the mean tempe- rature of that country. From a comparison of observations, Professer Mayer constructed the following empirical rule for finding the relation between the latitude and the mean temperature, in centesimal degrees, at the level of the sea. Multiply the square of the cosine of the latitude by the constant number 29, the pro- duct is the temperature. The variation of temperature for each degree of latitude is hence denoted centesimally with very great pre- cision, by half the sine of double the latitude. Mean temperatures. Height of curve of Latitude. Ce it. Fahr. congelation in feet. Oo 29 84-2 15207 5 A 28-78 83-8 15095 10 28-13 82-6 14764 15 27-06 80-7 14220 20 25-61 78-1 13478 25 23.82 74-9 12557 30 21-75 71-1 11484 35 19,46 67- 10287 40 17-01 62-6 9001 45 14-50 58-1 7671 50 11-98 53-6 6334 55 9-54 49.2 5034 60 7-25 45-0 3818 65 5-18 41-3 2722 70 3-39 38-1 1778 75 194 35-5 1016 80 0-86 33-6 457 85 0-22 32-4 117 90 0-0 32-0 00 The following table represents the results CLI 327 CLI of some interesting observations made under the direction of Mr. Ferguson of Raith, at Abbotshall in Fife, about 50 feet above the level of the sea, in latitude 56 10'. The 1816. large and strong bulbs of the thermometers were buried in the ground at various depths, while the stems rose above the surface for in- spection. 1817. 1 foot. 2 feet. 3 feet. 4 feet. 1 foot. 2 feet. 3 feet. 4 feet. January, 33 36.3 40.7 43<> 35.6 38.7 40.5 45.1 February, 33.7 36 39.0 42 37.0 40.0 41.6 42.7 March, 35 36.7 39.6 42.3 39.4 40.2 41.7 425 April, 39.7 38.4 41.4 43.8 45.0 42.4 42.6 42.6' May, 44.0 43.3 43.4 44.0 46.8 44.7 44.6 44.2 June, 51.6 50.0 47-1 45.8 51.1 49.4 476 47-8 July, 54.0 52.5 55.4 47-7 55.2 55.0 51.4 49.6 August, 50.0 52.5 50.6 49.4 53.4 53.9 52.0 50.0 September, 51.6 51.3 51.8 50.0 53.0 52.7 52.0 50.7 October, 47-0 49.3 49.7 49.6 45.7 49.4 49.4 49.8 November, 40.8 43.8 46.3 45.6 41.0 44.7 47-0 47-6 December. 35.7 40.0 43.0 46.0 37.9 40.8 44.9 46.4 Mean of whole year. 43.8 44-1 45.1 46 44.9 45.9 46.2 46.6 Had the thermometers been sunk deeper, they would undoubtedly have indicated 47-7. which is the mean temperature of the place, as is shown by a copious spring. The lake of Geneva, at the depth of 1000 feet, was found by Saussure to be 42 ; and below 160 feet from the surface there is no monthly variation of temperature. The lake of Thun, at 370 of depth, and Lucerne at 640, had both a temperature of 41, while the wa- ters at the surface indicated respectively 64 and 68i Fahr. Barlocci observed, that the Lago Sabatino, near Rome, at the depth of 490 feet, was only 44f , while the thermo- meter stood on its surface at 77- Mr. Jar- dine has made accurate observations on the temperatures of some of the Scottish lakes, by which it appears, that the temperature con- tinues uniform all the year round, about 20 fathoms under the surface. In like manner, the mine of Dannemora in Sweden, which presents an immense excavation, 200 or 300 feet deep, was observed at a period when the working was stopped, to have great blocks of ice lying at the bottom of it. The bottom of the main shaft of the silver mine of Kongs- berg in Norway, about 300 feet deep, is covered with perpetual snow. Hence, likewise, in the deep crevices of ./Etna and the Pyrenees, the snows are preserved all the year round. It is only, however, in such confined situations that the lower strata of air are thus permanently cold. In a free atmosphere, the gradation of temperature is reversed, or the upper regions are colder, in consequence of the increased capacity for heat of the air, by the diminution of the density. In the milder climates, it will be sufficiently accurate, in moderate elevations, to reckon an ascent of 540 feet for each cente- simal degree, or 100 yards for each degree on Fahrenheit's scale of diminished temperature. Dr. Francis Buchanan found a spring at Chit- long, in the lesser valley of Nepal, in Upper India, which indicated the temperature of 14-7 centesimal degrees, which is 8.1 below the standard for its parallel of latitude, 27 38'. Whence 8.1 X 540 = 4374 feet, is the ele- vation of that valley. At the height of a mile this rule would give about 33 feet too much. The decrements of temperature augment in an accelerated progression as we ascend. Ben Nevis, the highest mountain in Great Britain, stands in latitude 57, where the curve of congelation reaches to 4534 feet. But the altitude of the summit of the mountain is no more than 4380 feet ; and therefore, during two or three weeks in July, the snow disap- pears. The curve of congelation must evi- dently rise higher in summer, and sink lower in winter, producing a zone of fluctuating ice, in which the glaciers are formed. In calculating the mean temperature of countries at different distances from the equa- tor, the warmth has been referred solely to the sun. But Mr. Bald has published, in the first number of the Edinburgh Philosophical Jour- nal, some facts apparently incompatible with the idea of the interior temperature of the earth being deducible from the latitude of the place, or the mean temperature at the surface. The following table presents, at one view, the temperature of air and water, in the deepest coal-mines in Great Britain. Whitehaven Colliery, county of Cumberland. Air at the surface, 55 F. A spring at the surface, - 49 Water at the depth of 480 feet, . 60 Air at same depth, 63 Air at depth of 600 feet, 66 Difference between water at surface and at 480 feet, v .-'""* \\ CLI 328 CLI Workington Colliery, county of Cumberland. Air at the surface, 56 A spring at the surface, 48 Water 180 feet down, 50 Water 504 feet under the level of the ocean, and immediately beneath the Irish Sea, ... 60 Difference between water at surface and bottom, . " } , K 12 Teem Colliery, county of Durham. Air at pit bottom, 444 feet deep, 68 Water at same depth, 61 Difference between the mean tempe- rature of water at surface rr 49, and 444 feet down, 12 Percy Main Colliery, county of Northum- berland. Air at 'the surface, 42 Water about 900 feet deeper than the level of the sea, and under the bed of the river Tyne, v 68 Air at the same depth, 70 At this depth Leslie's hygrometer in- dicated dryness = 83. Difference between mean temperature of water at surface = 49, and at 900 feet down, ... 19 J arrow Colliery, county of Durham. Air at surface, .... 49 Water 882 feet down, 68 Air at same depth, ^ , * 70 Air at pit bottom, . 64 Difference between the mean tempera- ture of water at surface = 49, and 882 feet down, 19 The engine pit of Jarrow is the deep- est perpendicular shaft in Great Britain, being 900 feet to the foot of the pumps. Killinguorth Colliery, county of Northum- berland. Air at the surface, - 48 Air at bottom of pit, 790 feet down, 51 Air at depth of 900 feet from the surface, after having traversed a mile and a half from the bottom of the downcast pit, 70 Water at the most distant forehead or mine, at the great depth of 1200 feet from the surface, . - 74 Air pt the same depth, 77 Difference betwixt the mean tempe- rature of the water at the surface = 49, and water at the depth of 1200 feet, ... 25 Distilled water boils at this depth at 213 Do. do. at surface, M. Humboldt has stated, that the tempe- rature of the silver mine at Valenciana in New Spain is 11 above the mean temperature of Jamaica and Pondicherry, and that this tern- perature is not owing to the miners and their lights, but to local and geological causes. To the same local and geological causes we must ascribe the extraordinary elevation of tempe- rature observed by Mr. Bald. He further re- marks, that the deeper we descend, the drier we find the strata, so that the roads through the mines require to be watered, in order to prevent the horse-drivers from being annoyed by the dust. This fact is adverse to the hy- pothesis of the heat proceeding from the che- mical action of water on the strata of coal. As for the pyrites intermixed with these strata, it does not seem to be ever decomposed, while it is in situ. The perpetual circulation of air for the respiration of the miners must prevent the lights from having any considerable influence on the temperature of the mines. The meteorological observations now made and published with so much accuracy and re- gularity in various parts of the world will soon, it is hoped, make us better acquainted with the various local causes which modify climates, than we can pretend to be at present. The accomplished philosophical traveller, M. de Humboldt, published an admirable sys- tematic view of the mean temperatures of dif- ferent places, in the third volume of the Me- moirs of the Society of ArcueiL His paper is entitled, Of Isothermal Lines (lines of the same temperature), and the Distribution of Heat over the Globe. By comparing a great number of observations made between 46 and 48 N. lat, he found, that at the hour of sun- set the temperature is very nearly the mean of that at sunrise and two hours after noon. Upon the whole, however, he thinks, that the two observations of the extreme temperatures will give us more correct results. The difference which we observe in culti- vated plants depends less upon mean tempe- rature than upon direct light and the serenity of the atmosphere ; but wheat will not ripen if the mean temperature descend to 47-6. Europe may be regarded as the western part of a great continent, and subject to all those influences which make the western sides of all continents warmer than the eastern. The same difference that we observe on the two sides of the Atlantic exists on the two sides of the Pa- cific. In the north of China, the extremes of the seasons are much more felt than in the same latitudes in New California, and at the mouth of the Columbia. On the eastern side of North America, we have the same extremes as in China ; New York has the summer of Rome, and the whiter of Copenhagen ; Que- bec has the summer of Paris, and the winter of Petersburgh. And in the same way in Pekin, which has the mean temperature of Britain, the heats of summer are greater than those at Cairo, and the cold of winter as severe as that at Upsal. This analogy between the eastern coasts of Asia and of America suf- ficiently proves, that the inequalities of the CLI 329 CLI seasons depend upon the prolongation and en- largement of the continents towards the pole, and upon the frequency of N. W. winds, and not upon the proximity of any elevated tracts of country. Ireland, says Humboldt, presents one of the most remarkable examples of the combination of very mild winters with cold summers ; the mean temperature in Hungary for the month of August is 71. G ; while in Dublin it is only 60.8. In Belgium and Scotland, the winters are milder than at Milan. In the article Climate, Supplement to the Encyclopaedia Britannica, the following simple rule- is given for determining the change of temperature produced by sudden rarefaction or condensation of air. Multipty 25 by the difference between the density of air and its reciprocal, the product -will be the difference of temperature on the centigrade scale. Thus, if the density be twice, or one half 25 X (2 i) = 37 cent. = 67-5 Fahr. indicates the change of temperature by doubling the density or rarity of air. Were it condensed 30 times, then, by this formula, we have 749 for the elevation of temperature, or 25 (30 ^)- But M - Gav Lussac says, that a condensation of air into one-fifth of its volume, is sufficient to ignite tinder ; a degree of heat which he states at 300 centigrade = 572 Fahr. (Journal of Science, vol. vii. p. 177) This experimental result is incompatible with Professor Leslie's formula, which gives only 112-5 for the heat produced by a condensa- tion into one-fifth. It appears very probable, that the climates Of European countries were more severe in an- cient times than they are at present, Cassar says, that the vine could not be cultivated in Gaul, on account of its winter-cold. The rein-deer, now found only hi the zone of Lap- land, was then an inhabitant of the Pyrenees. The Tiber was frequently frozen over, and the ground about Rome covered with snow for several weeks together, which almost never happens in our times. The Rhine and the Danube, in the reign of Augustus, were gene- rally frozen over, for several months of winter. The barbarians who overran the Roman em- pire a few centuries afterwards^ transported their armies and waggons across the ice of these rivers. The improvement that is con* tinually taking place in the climate of America, proves, that the power of man extends to phe- nomena, which, from the magnitude and va- riety of their causes, seemed entirely beyond his control. At Guiana, in South America, within five degrees of the line, the inhabitants living amid immense forests, a century ago, were obliged to alleviate the severity of the cold by evening fires. Even the duration of the rainy season has been shortened by the clearing of the country, and the warmth is so increased, that a fire now would be deemed an annoyance. It thunders continually in the woodSj rarely in the Cultivated parts. Drainage of the ground, and removal of forests, however, cannot be reckoned among the sources of the increased warmth of the Italian winters. Chemical writers have omit- ted to notice an astronomical cause of the pro- gressive amelioration of the climates of the northern hemisphere. In consequence of the apogee portion of the terrestrial orbit being contained between our vernal and autumnal equinox, our summer half of the year, or the interval which elapses between the sun's cross- ing the equator in spring, and in autumn, is about seven days longer than our winter half year. Hence also, one reason for the relative coldness of the southern hemisphere. Isothermal Bands, and Distribution of Heat over the Globe. The temperatures are expressed in degrees of Fahrenheit's thermometer ; the longitudes are counted from east to west, from the first meridian of the observatory of Paris. The mean temperatures of the seasons have been calculated, so that the months of December, January, and February, form th mean tem- perature of the winter. The mark * is pre- fixed to those places, the mean temperatures of which have been determined with the most precision, generally by a mean of 8000 ob- servations. The isothermal curves having a concave summit in Europe, and two convex summits in Asia and Eastern America, the climate is denoted to which the individual places belong : CLI 330 CLI Mean temp, of coldest month. & CO 1-1 t*Tt< SO CO 1 -HO JN l^ CO 05 CO ' i TfCOCOCO . CO CO iO CO CO O5COO5 iO-^O "<*rHO'-it^O(MCOCOCOCOO5CO 3 1 _ *. - *. HIOJJ puBq oj \f uiojj puBq CLI 331 CLI ^ O (M Tj* ^ o (NO ^ O CO CO CO ^ N CO o cp oco 10 CO Irish, Queen's County, No. 39. } 9.10 10.30 87-491 86.560 3.409 3.140 1.403 1.403 1.656 ^S Stone-wood, Giant's Causeway, Oak wood, 33.37 80.00 54.697 19.500 1 1.933 / 0.500/f "1.150 mtf j / & * V ** tfY . , w . Vv y-V . o*v It was remarked long ago by Macquer, that nitre detonates with no oily or inflammable matter, until such matter is reduced to coal, and then only in proportion to the carbona- ceous matter it contains. Hence it occurred to Mr. Kirwan, that as coals appear in distil- lation to be for the most part merely com- pounds of carbon and bitumen, it should fol- low, that by the decomposition of nitre, the quantity of carbon in a given quantity of every species of coal may be discovered, and the proportion of bitumen inferred. This cele- brated chemist accordingly projected on a cer- tain portion of nitre in a state of fusion, suc- cessive fragments of various kinds of coal, till the deflagration ceased. Coal, when in fine powder, was thrown out of the crucible. The experiments seem to have been judiciously performed, and the results are therefore en- titled to as much confidence as the method permits. Lavoisier and Kirwan state, that about 13 parts of dry wood charcoal decom- pose 100 of nitre. 10(1 parts Charcoal. Bitumen. Earth.Sp.gr. Kilkenny coal, 97.3 3.7 1.526 Comp. cannel, 75.2 2 1.68 maltha 3.1 1.232 Swansey, 73.53 23.14 mixt. 3.33 1.357 71.43 23.37 do. 5.20 1.351 61.73 36.7 do. 1.57 1-268 58.00400 do. 1.271 57.0 41.3 1.7 1.257 47.62 32.52 mal. 20.0 1.426 31.0 68.0 bitumen 1.117 Leitrim, Wigan, Newcastle, Whitehaven, Slaty cannel, Asphalt, Maltha 8.0 2.07 100 parts of the best English coal give, of coak, . . 63. by Mr. Jars. 100 do. . . . 73. Hielm. 100 do. Newcastle do. 58. Dr. Watson. Mr. Kirwan says he copied the result, for Newcastle coal, from Dr. Watson. The foliated or cubical coal, and slate coal, disti are chiefly used as iVel'in. private hous caking coals, for smithy forges ; the si from its keeping open, answfcrs-best f ~ great heats in a wind furnace, as in on the great scale ; and glance coal is used for drying grain and malt. The coals of South Wales contain less volatile matter than either the English or the Scotch ; and hence, in equal weight, produce a double quantity of cast iron in smelting the ores of this metal. It is sup- posed that 3 parts of good Newcastle coals are equivalent, as fuel, to 4 parts of good Scotch coals. Werner has ascertained three distinct coal formations, without including the beds of coal found in sandstone and limestone formations. The first or oldest formation, he calls the in- dependent coal formation, because the indi- vidual depositions of which it is composed, are independent of each other, and are not con- nected. The second is that which occurs in the newest floetz-trap formation ; arid the third occurs in alluvial land. Werner observes, that a fourth formation might be added, which would comprehend peat and other similar sub- stances ; so that we would have a beautiful and uninterrupted series, from the oldest for- mation to the peat, which is daily forming under the eye. The independent formation contains exclu- sively coarse coal, foliated coal, cannel coal, slate coal, a kind of pitch coal, and slaty glance coal. The latter was first found in this forma- tion in Arran, Dumfries-shire, Ayrshire, and at Westcraigs, by Professor Jameson. The formation in the newest floetz-trap contains distinct pitch coal, columnar coal, and con- choidal glance coal. The alluvial formation contains almost exclusively earth coal and bituminous wood. The first formation, be- sides coal, contains three rocks which are peculiar to it ; these are a conglomerate, which is more or less coarse-grained ; a friable sand- stone, which is always micaceous ; and lastly, COA 336 COA slate-clay. But besides these, there occur also beds of harder sandstone, marl, limestone, porphyritic stone, bituminous shale, clay-iron- stone ; and, as discovered by Professor Jame- son, greenstone, amygdaloid, and graphite. The slate-clay is well characterized by the great variety of vegetable impressions of such plants as flourish in marshes and woods. The smaller plants and reeds occur in casts or im- pressions always laid in the direction of the strata ; but the larger arborescent plants often stand erect, and their stems are filled with the substance of the superincumbent strata, which seems to show that these stems are in their original position. The leaves and stems re- semble those of palms and ferns. The central, northern, and western coal mines of England ; the river coal districts of the Forth and the Clyde, and the Ayrshire, and in part the Dum- fries-shire coals, belong to this formation, as well as the coals in the northern and western parts of France. By far the most valuable and extensive beds of coal which have been found and wrought are in Great Britain. The general form of out great independent coal-beds is semi-cir- cular, or semi- elliptical, being the segment of a great basin. The strata have a dip or de- clination to the horizon of from 1 in 5 to 1 in 20. They are rarely vertical, and seldom per- fectly horizontal to any considerable extent. Slips and dislocations of the strata, however, derange more or less the general form of the Those who wish to understand the most improved modes of working coal mines, will be amply gratified by consulting, A Report on the Leinster Coal District, by Richard Griffith, Esq. Professor of Geology, and Mining En- gineer to the Dublin Society. The author has given a most luminous view of Mr. Buddie's ingenious system of working and ventilating, in which from 7-8ths to 9-10ths of the whole coal may be raised, instead of only ^, which was the proportion obtained in the former modes. Mr. Griffith has since published some other reports, the whole constituting an inva- luable body of mining information. COAL GAS. When coal is subjected in close vessels to a red heat, it gives out a vast quantity of gas, which being collected and purified, is capable of affording a beautiful and steady light, in its slow combustion through small orifices. Dr. Clayton seems to have been the first who performed this experiment, with the view of artificial illumination, though its application to economical purposes was unac- countably neglected for about 60 years. At length Mr. Murdoch of the Soho Foundry, instituted a series of judicious experiments on the extrication of gas from ignited coal ; and succeeded in establishing one of the most ca- pital improvements which the arts of life have ever derived fvora philosophical research and sagacity. In the year 1798, Mr. Murdoch, after se- veral trials on a small scale five years before, constructed, at the foundry of Messrs. Bolton and Watt, an apparatus upon a large scale, which during many successive nights was ap- plied to the lighting of their principal building ; and various new methods were practised of washing and purifying the gas. In the year 1805, the cotton-mill of Messrs. Philips and Lee, reckoned the most extensive in the king, dom, was partly lighted by gas under Mr. Murdoch's direction ; and the light was soon extended over the whole manufactory. In the same year, I lighted up the large lecture-room of Anderson's Institution with coal-gas, gene- rated in the laboratory; and continued the illumination every evening through that and the succeeding winter. Hence I was induced to pay particular attention to the theory and practice of its production and use. If coal be put into a cold retort and slowly exposed to heat, its bitumen is merely vola- talized in the state of condensible tar. Little gas, and that of inferior illuminating power, is produced. This distillatory temperature may be estimated at about 600 or 700 F. If the retort be previously brought to a bright cherry-red heat, then the coals, the instant after their introduction, yield a copious supply of good gas, and a moderate quantity of tarry and ammoriiacal vapour. But when the retort is heated to nearly a white incandescence, the part of the gas richest in light is attenuated into one of inferior quality, as I have shown in detailing Berthollet's experiments on CAR- BURETTED HYDROGEN. ApOUnd of good cannel coal, properly treated in a small appa- ratus, will yield 5 cubic feet of gas, equivalent in illuminating power to a mould candle six in the pound. See CANDLE. On the great scale, however, 3| cubic feet of good gas are all that should be expected from 1 pound of coal. A gas jet, which con- sumes half a cubic foot per hour, affords a steady light equal to that of the above candle. According to Mr. Murdoch's statement, presented to the Royal Society, 2500 cubic feet of gas were generated in Mr. Lee's retort from 7 cwt. = 784 Ibs. of cannel coal. This is nearly 3 cubic feet for every pound of coal, and indicates judicious management. The price of the best Wigan cannel is 13$d. per cwt. (22s. 6d. per ton) delivered at Mr. Lee's mill at Manchester ; or about 8*. for the seven hundred weight. About of the above quan- tity of good common coal, at 10s. per ton, is required for fuel to heat the retorts. Nearly of the weight of the coal remains in the retort in the form of coak, which is sold on the spot at Is. 4d. per cwt. The quantity of tar produced from each ton of cannel coal, is from 11 to 12 ale gallons. The economical statement for one year is given by Mr. Murdoch thus: COA S37 COA Cost of 1 10 tons of cannel coal, Ditto of 40 tons of common ditto, Deduct the value of 70 tons of coak, .125 20 145 93 The annual expenditure in coal, without allowing any thing for tar, is - 52 And the interest of capital, and wear and tear of apparatus, ... 350 Making the total annual expense of the gas apparatus about - - 600 That of candles to give the same light, 2000 If the comparison had been made upon an average of three hours per day, instead of two hours, (all the year round), then the cost from gas would be only *;..: . - 650 Ditto candles, - .. - 3000 The peculiar softness and clearness of this light, with its almost unvarying intensity, soon brought it into great favour with the work-people. And its being free from the inconvenience and danger resulting from the sparks and frequent snuffing of candles is a circumstance of material importance, tending to diminish the hazard of fire, and lessening the high insurance premium on cotton-mills. The cost of the attendance upon candles would be fully more than upon the gas apparatus ; and upon lamps greatly more, in such an establishment as Mr. Lee's. The preceding statements are of standard authority, far above the suspicion of empiricism or exaggeration, from which many subsequent statements by gas book compilers are by no means exempt. At the same manufactory, Dr. Henry has lately made some useful experiments on the quality of the gas disengaged from the same retort at different periods of the decomposition. I have united in the following table, the chief part of his results. He collected in a bladder the gas, itissued from an orifice in the pipe, between the retorts and the tar pit ; and pu- rified it afterwards by agitation in contact of quicklime and water. Ten cwt. or 1120 Ibs. of coal were contained in the retorts. 100 measures too measures 100 measures 1 0Oaombusti ble of impure gas of purified gas of purified gas, exclusive Hours from contain, contain, gas. of azote. 1 commence- ment. Sulph. hydr. Carb. acid. Olef. Jiner infl. jnses. Azott Cons, oxyg. Give car. ac. Take oxyg. Garb, acid. | s **S| 16 64 20 180 94 225 118 1 1 3 *l 18 77^ 210 112 220 117 a . 3 2^ 24 15 80 5 200 108 210 114 s? 5 % 13 72 15 176 94 206 108 p* 7 2 2? 9 76 15 170 83 200 98 9 2 8 77 15 150 73 176 85 lo* o 2 6 74 20 120 54 150 70 12 o* 4 76 20 82 36 103 45 -3 . 1 3 3 10 90 164 91 164 91 3| 3 2 2 9 91 168 93 168 93 *s i3 5 3 2 6 94 132 70 132 70 gO 7 1 3 5 80 15 120 64 140 -75 S 3 9 1 24 2 89 9 112 60 123 66 < 11 1 1 85 15 90 43 106 50 Dr. Henry conceives that gas to have the greatest illuminating power, which, in a given volume, consumes the largest quantity of oxy- gen ; and that hence the gas of cannel coal is one-third better than the gas from common coal. 3500 cubic feet of gas were collected from 1120 pounds of the cannel coal; and only 3000 from the same weight of the Clifton coal. From the preceding table we see also, that the gas which issues at the third hour contains, in 100 parts, of sulphuretted hydrogen and carbonic acid, each 2, of azote 4|, olefiant gas 14, and of other inflammable gases 76 parts. A cubic foot of carbonic acid weighs 800 gr. A cubic foot of sulphuretted hydrogen weighs 620. The first takes about 1026 gr. of lime for its saturation ; the second about 1070 ; and hence 1050, the quantity assigned by Dr. Henry for either, is sufficiently exact. 100 cubic feet of the above impure gas, containing 5 cubic feet of these two gases, will require at least 2100 grains of lime, or about 5 oz. avoir- dupois for their complete condensation. The proportion employed by Mr. Lee is, 5 pounds of fresh burned lime to 200 cubic feet of gas. The lime, after being slaked, is sifted and mixed with a cubic foot (7.48 wine gal- lons) of water. This quantity of cream of lime is adequate to the ordinary purification of the gas. Yet it will still slightly darken a COA 338 COA card, coated with moistened white lead. A second exposure to lime makes it absolutely pure. Measures. Oxygen. Carb. ac. 100 crude gas, consume 190 give 108 100 gas, once washed, 175 100 100 do. twice washed, 175 100 What is separated by the first washing is probably vapour of bitumen or petroleum, which would injure the pipes by its deposi- tion, more than it would profit by any in- creased quantity of light. Though we thus see that the second washing in the above ex- periment condensed none of the olefiant gas, it is prudent not to use unnecessary agitation with a large body of water. The carbonate of lead precipitated from a cold solution of the acetate, by carbonate of ammonia, washed with water, and mixed with a little of that liquid into the consistence of cream, is well adapted to the separation of sulphuretted hydrogen from coal gas. The carbonic acid may then be withdrawn from the residuary gas, by a little water of potash. We mu*$t now determine the azote present, which is easily done by firing a volume of this fas with thrica its volume of pure oxygen. Vliat remains after agitation with water of potash, is a mixture of azote and oxygen. Explode it with hjdrogen; one-third of the diminution of volume shows the oxygen ; the rest is azote. We have now to eliminate three quantities, viz. the volume of olefiant gas, that of common carburetted hydrogen, and that of carbonic oxide. Mr. Faraday has proved that chlorine acts pretty speedily on the second species of carburetted hydrogen, and therefore it cannot be employed with the view of condensing merely the first species. In contact with moisture, chlorine acts also rapidly on carbonic oxide, giving birth to mu- riatic and carbonic acids. If we be therefore deprived of all known means of chemical eli- mination, we shall find a ready and successful resource in the doctrines of specific gravity. In any mixture of two solids, two liquids, or two gases, whose specific gravities are known, it is easy to infer from the specific gravity of the compound (when the mixture is effected without change of volume) the relative weights of the two constituents. Thus if we apply to an alloy of gold and zinc the old problem of Archimedes, we shall determine exactly the proportion of each metal present, because the volume of the alloy is very nearly the sum of the volumes of its ingredients. I have long applied this problem to gaseous mixtures, and found it a very convenient means of verifica- tion on many occasions, particularly in exa- mining the nature of the residuary air in the lungs of the galvanized criminal, of which an account is given in the 1 2th Number of the Journal of Science. PROBLEM. In 100 measures of mixed gases, consisting, for example, of olrjiant gas, car- bonic oxide, and subcarbvretted hydrogen, in unknown proportions, to determine the quan- tity of each. The first step is to find the quantity of the two denser gases, which have the same specific gravity:^: 0-9720. RULE. Multiply by 100, the difference between the specific gravity of the mixture and that of the lighter gas. Divide that num- ber, by the sum of the differences of the sp. gr. of the mixture, and that of the denser and lighter gas ; the quotient is the per-ccntagc of the denser. See Gregory's Meclianics, vol. i. p. 3G4. EXAMPLE. A mixture of olefiant gas, carbonic oxide, and subcarburetted hydrogen, has a sp.gr. of 0-638. What is the proportion per cent, of the first two? Sp. gr. of subcarb. hydrogen is 0.555 ; 0-638 0.555 =:0.083.-. 100 X 0.083 = 8.3 difference 0.334 n A , - difference 0.083 Sum = - 417 And ~~:= 20 = volume of the two heavier gases; and therefore there are 80 of the lighter gas. Hence, having fired the whole with oxygen, we must allow 160 of oxygen, for saturating the 80 measures of the subcar- buretted hydrogen. Then let us suppose 35 cubic inches more oxygen to have been con- sumed. We know that the saturating power of olefiant gas, and of carbonic oxide with oxygen, is in the ratio of 3 to 0-5. Therefore, the ~ , ,, 35 (20 x 0.5) 25 quantity of olef. gas. = - 3 _ UtS - ^ = 10 measures. We see now, that a gas of sp. gr. 0.638 consists of 0-8 measures subcarb. hydrogen = 0.444 0.1 do. olefiant gas = 0.097 0.1 do. carb. oxide = 0-097 0-638 For further details, see GAS. Dr. Henry gives, at the end of his experi- ments, (Manchester Memoirs, vol. iii. second series), some hypothetical representations of the constitution of coal gases, in one of which he assigns, 2 of carburetted hydrogen, 2 of carbonic oxide, and 15 of pure hydrogen, in 1 8| mea- sures. With mixtures of three gaseous bodies, the problem of eliminating the proportion of the constituents by explosion with oxygen, becomes complex, and several hypothetical proportions may be proposed. But I can hardly imagine, that pure hydrogen should be disengaged from ignited coal. There is no violation of the doctrine of multiple pro- portions, in conceiving a compound to exist COA 339 COA in which three or more atoms of hydrogen may be united with one of carbon. Berthol- let's experiments render this view highly pro- bable. If the above hypothetical numbers were altered to 1.6; 2.4; and 15; their ac- cordance with Dr. Henry's experiments would be improved. Now, this is a considerable la- titude of adjustment. The principles laid down at the commence- ment of this article show, that the more uni- formly the coal undergoes igneous decomposi- tion, the richer is the gas. The retorts, if cylindrical, should not exceed, therefore, 12 or 14 inches diameter, and six or seven feet in length. Compressed cylinders, whose length is 44 feet, breadth 2 feet, and inside vertical diameter about 10 inches, have been found to answer well at Glasgow. The cast iron of which they are composed must be screened from the direct impulse of the fire by a case of firebrick. On the maximum quantity of gas procurable from coal, it is difficult to acquire satisfactory information at the great gas establishments. Exaggeration seems to be the prevailing foible. Mr. Accum gives the following tables, as the maximum results of his own experiments, made at the Royal Mint gas works : One chaldron = 27 cwt. of coal produces, Cubic feet of gas. Scotch cannel coal, . . 19.890 Lancashire Wigan cannel, 19-608 Yorkshire cannel, Wakefield, 18.860 Staffordshire coal, 1st variety, 9-748 By experim. aO 2d do. 10.223 Birmingham > 3d do. 10.866 gas-works, j 4th do. 9-796 Gloucestershire coal, HighDelph, 16.584 do. Low Delph, 12.852 do. Middle Delph, 12.096 Newcastle coal, Hartley, 16.120 Cowper's High Main, 15.876 Tanfield Moor, 16.920 Pontops, . 15.112 The following varieties of coal, according to Mr. Accum, contain a less quantity of bi- tumen, and a larger quantity of carbon than the preceding. They soften, swell, and cake on the fire, and are well calculated for the pro- duction of coal gas : One chaldron produces, Newcastle coal, Russel's Wall's-end, 16.876 Bewicke and Crastor's Wall's -end, 16-897 Heaton Main, 15.876 Bleyth, . 12.096 Elden Main. . 9-600 Primrose Main, 8.348 Concerning the duration of the decomposi- tion of a retort- charge of one cwt. various opinions are maintained. Mr. Peckston's experiments at the Gas-light and Coak Com- pany's works, Westminster station, seem to prove, that decided advantages attend the continuance of the process for eight hours, in preference to six, or any shorter period. The average product of gas, from one chaldron of Newcastle coals, at six hours' charges, he states at 8300 cubic feet, and at those of eight hours, at 10,000. On 76 retorts worked for a week at the latter rate, he gives a statement to prove, that there is a saving of -77- 18s. above the former rate of working. Two men, one by day, and one by night, can attend nine or ten retorts, at eight hour charges, of 100 pounds of coal each. Scotch cannel yields its gas most readily, or 1-00 Newcastle coal, -1-04 Gloucester Low Delph, v 1-08 Newcastle, Brown's Wall's-end, 1-18 Warwickshire, 1-65 Hence, the latter kinds afford good gas, long after the former are exhausted. The following table, by Mr. Peckston, ex- hibits the ratio at which the gas is evolved from Bewicke and Crastor's Wall's-end. coal, when the retorts are worked at eight hours* charges : Cubic feet. Sum. During the 1st hour are ge- nerated, 2000 2d, 1495 3495 3d, 1387 4882 4th, 1279 6161 5th, 1189 7350 6th, 991 8341 7th, 884 9225 8th, 775 10000 We have already explained the principles of purifying gas by milk of lime. But previous to its agitation with that liquid, it should be made to traverse a series of refrigeratory pipes submersed under cold water. A vast variety of apparatus, some very ingenious, but many absurd, have been contrived within these few years, for exposing gas to lime in the liquid or dry state. Mr. Accum and Mr. Peckston have been at much pains in describing several of them. The gas-holder is now generally pre- ferred of a cylindrical shape, like an immense drum, open at bottom ; and flat, or slightly conical at top. The diameter is from 33 to 45 feet in the large establishments, and the height from 18 to 24. The average capacity is from 15-000 to 20-000 cubic feet. It is suspended in a tank of water by a strong iron chain fixed to the centre of its summit, which, passing round a pulley, bears the counter- COA 340 COA weight. When totally immersed in water, the sheet -iron, of which the gas-holder is com- posed, loses hydrostatically about two-fifteenths of its weight ; or if equipoised when immersed, it becomes two-fifteenths heavier when in air. minus the buoyancy of the in eluded gas. The mean sp. gr. of well purified coal-gas by Dr. Henry's late experiments may be computed at 676, to air called 1-000 ; or in round num- bers, its density may be reckoned two-thirds of that of air. One cubic foot of air weighs 52? gr., one cubic foot of gas weighs 351 gr. ; the difference is 176 gr. Hence, 40 cubic feet have a buoyancy of one pound avoirdupois. The hydrostatic compensation is obtained by making the weight of that length of the suspending chain which is between the top of the immersed gasometer and the tangential point of the pulley-wheel, equal to one-fifteenth the weight of the gasometer in pounds, minus its capacity in cubic feet, divided by twice 40, or 80. Thus, if its weight be 4 tons, or 8960 Ibs , and its capacity 15000 cubic feet, a length of chain equal to the height of the gasometer, or to its vertical play, should weigh 597 Ibs., without allowing for buoyancy. In this case, the gasometer, when out of water, would have the buoyancy of that liquid, replaced by the passage of these 597 Ibs. to the opposite side of the wheel-pulley, so that twice that weight = 1 194 Ibs. would then be added to the con- stant counterpoise. When the gasometer again sinks, and loses its weight by the displacement of the liquid, successive links of the chain come over above it, augmenting its weight, and diminishing that of the counterpoise by a twofold operation, as in taking a weight out of one scale, and putting it in the other. But we must now introduce the correction for the buoyancy of the combustible gas. In ordinary cases we must regard it as holding a portion of petroleum vapour diffused through it, and cannot fairly estimate its sp. gravity at less than 0-760 ; whence nearly 50 cubic feet have a buoyancy of one pound over the same bulk of atmospheric air. If we divide 15000 by 50, the quotient z= 300 is the double of what must be deducted in pounds weight from the hydrostatic compensation. Thus 597 150 447, is the weight of the above portion of chain. When the gasometer attains its greatest elevation, these 447 Ibs. hang on the opposite side of the wheel, constituting an in- creased counterpoise of twice 447=894, to which, if we add the total buoyancy of the in- cluded gas =. 300 Ibs. we have the sum 1 194, equal to the total increase of the weight of the iron vessel on its suspension in air. The principles of the distribution of gas are exhibited in the following table given by Mr. Peckston. The gas-holder is worked at a pressure of one vertical inch of water, and each argand burner consumes five cubic feet per hour. s . JP Cubic feet passing per hour. Burners supplied. I 20 4 | 50 10 | 90 18 160 32 | 250 50 i 30 76 1 500 100 2 2000 400 3 4500 900 4 8000 1600 5 12500 2500 6 18000 3600 7 24500 4900 8 32000 6400 .9 40500 8100 10 50000 10000 12 72000 14400 14 98000 19-600 16 128000 25-600 18 162000 32-400 The following statement is given by Mr. Accum. An argand burner, which measures in the upper rim half an inch in diameter be- tween the holes from which the gas issues, when furnished with five apertures l-25th part of an inch diameter, consumes two cubic feet of gas in an hour, when the gas flame is one and a half inch high. The illuminating power of this burner is equal to three tallow candles eight in the pound. An argand burner three-fourths of an inch in diameter as above, and perforated with holes l-30th of an inch diameter (what number ? probably 15) consumes three cubic feet of gas in an hour, when the flame is 2| inches high, giving the light of four candles eight to the pound. And an argand burner seven-eighths of an inch diameter as above, perforated with 18 holes l-32d of an inch diameter, consumes, when the flame is three inches high, four cubic feet of gas per hour, producing the light of six tallow candles eight to the pound. Increased length of flame makes imperfect combustion, and diminished intensity of light. And if the holes be made larger than l-25th of an inch, the gas is incompletely burnt. The height of the glass chimney should never be less than five inches. The argand burner, called No. 4. when burnt in shops from sunset till nine o'clock, is charged three pounds a-year. The diameter of its circle of holes is five-eighths of an inch, and of each hole l-32d of an inch. It is drilled with 12 holes, 5-32ds of an inch from the centre of one to the centre of another. Height of this burner 1 inches. No. 6. argand burner. 15 apertures of COA 341 COB l-32d of an inch ; diameter of their circle three-fourths of an inch; height of burner two inches : charge per annum four guineas. According to Mr. Accum, one gas lamp, consuming 4 cubic feet of gas in an hour, if situated 20 feet distant from the main which supplies the gas, requires a tube not less than a quarter of an inch in the bore ; '2 lamps, 3 feet distance, require a tube three-eighths of an inch ; 3 lamps, 30 feet distance, require a tube three-eighths ; 4 lamps, at 40 feet, one- half inch bore ; 10 lamps, at 100 feet distance, require a tube three-fourths of an inch j and 20, 150 feet distant, 1^ inch bore. We have seen that the average product in London from 1 pound of coal in 8 hours, is 3^ cubic feet. In the Glasgow coal gas esta- blishment, which is conducted by engineers skilled in the principles of chemistry and me- chanics, fully 4 cubic feet of gas are extracted from every pound of coal of the splent kind in 4 hour charges, from retorts containing each 120lbs. ; which is about two-thirds of their capacity. The decomposing heat is much the same as that used in London, but the retorts are compressed cylinders, a little concave be- low. Hence in 8 hours, fully double the London quantity of gas is obtained from a retort in Glasgow. An ingenious pupil of mine, lately em- ployed by a projected gas company in Glas- gow to visit the principal factories of gas in England, made a series of accurate experi- ments on its illuminating quality in the differ- ent towns. For this purpose, he carried along with him a mould candle, six in the pound, and a single-jet gas-nozzle. By attaching this to a gas-pipe, and producing a flame of de- terminate length, (three inches), he could then, by the method of shadows, compare the flame of the gas with that of his candle, and ascertain their relative proportions of light. He found that the average illuminating power of the gas in the English establishments, was to that of the Glasgow company as four to five ; the worst being so low as three to five, and the best, as five to six. If we therefore multiply this ratio, into the double product of gas obtained in the Glasgow gas-work, we shall have the proportion of light generated here, and in London, from an equal-sized re- tort, in an equal time, as 100 to 40. This result merits entire confidence. In the sequel of the article LIGHT, in this Dictionary, instructions will be given how to calculate the relative illuminating powers of different flames. "When the tar is passed through ignited iron pipes, it yields from 10 to 15 cubic feet of gas per pound. The deposit of refractory asphal- tum, however, is very apt to obstruct the pipes; and the light afforded is perhaps of inferior quality. Hence tar is decomposed in very few establishments. The film of petroleum, which floats on the water of the gasometer tank, and that pro- cured from the tar by distillation, have been used instead of oil for street-lamps. The lamp fountain is kept on the outside of the glass lantern, and the flame is made small, to prevent an explosion of the vaporized naphtha. 1430 Ibs. of tar by boiling yield nine cwt. of good pitch. From a chaldron of Newcastle coal about 200 Ibs. of ammoniacal liquor are obtained ; a solution chiefly of the carbonate and sulphate. The strongest liquor comes from the caking coal. A gallon, or 8^- Ibs. usually requires for saturation from fifteen to sixteen ounces of oil of vitriol, sp. gr. 1-84. To obtain subcarbonate of ammonia, 125 Ibs. of calcined gypsum in fine powder are added to 108 gallons of the ammoniacal liquor. The mixture is stirred, and the cask containing it is then closed for three or four hours. Sixteen ounces of sulphuric acid are now mixed in ; and the whole allowed to remain at rest for four or six hours. The supernatant sulphate of ammonia is next evaporated till it crystallize. One hundred weight of the dry crystals is mixed with about their weight of dry chalk in powder, and sublimed from a cylindrical iron retort into a barrel -shaped receiver of lead. A charge of 120 Ibs. of the mixture is usually decomposed in the course of twenty-four hours. One hundred weight of dry sulphate of ammonia is said to produce from sixty to sixty-five pounds of solid sub- carbonate of ammonia. If the sulphate of /; ammonia, mixed with common salt, is exposed to a subliming heat, sal ammoniac is obtained. For Oil Gas, see OIL. COATING, orLORICATION. Chaptal recommends a soft mixture of marly earth, first soaked in water, and then kneaded with fresh horse-dung, as a very excellent coating. The valuable method used by Mr. Willis of Wapping to secure or repair his retorts used in the distillation of phosphorus, deserves to be mentioned here. The retorts are smeared with a solution of borax, to which some slaked lime has been added, and when dry, they are again smeared with a thin paste of slakid lime and linseed oil. This paste being made siomewhat thicker, is applied with success, during the distillation, to mend such retorts as crack by the fire. COBALT. A brittle, somewhat soft, but difficultly fusible metal, of a reddish grey colour, of little lustre, and a sp. gr. of 86. Its melting point is said to be 130 Wedge- wood. It" is generally associated in its ores with nickel, arsenic, iron, and copper; and the cobalt of commerce usually contains a proportion of these metals. To separate them, calcine with 4 parts of nitre, and wash away, with hot water, the soluble arseniate of potash. Dissolve the residuum in dilute nitric acid, and immerse a plate of iron in the solution, to precipitate the copper. Filter the liquid, and COB 342 COB evaporate to dryness. Digest the mass with water of ammonia, which will dissolve only the oxides of nickel and cobalt. Having ex- pelled the excess of alkali by a gentle heat from the clear ammoniacal solution, add cau- tiously water of potash, which will precipitate the oxide of nickel. Filter immediately, and boil the liquid, which will throw down the pure oxide of cobalt. It is reduced to the metallic state by ignition in contact with lamp-black and oil. Mr. Laugier treats the above ammoniacal solution with oxalic acid. He then redissolves the precipitated oxalates of nickel and cobalt in concentrated water of ammonia, and exposes the solution to the air. As the ammonia exhales, oxalate of nickel, mixed with ammonia, is deposited. The nickel is entirely separated from the liquid by re- peated crystallizations. There remains a com- bination of oxalate of cobalt and ammonia, which is easily reduced by charcoal to the metallic state. The small quantity of cobalt remaining in the precipitated salt of nickel, is separated by digestion in water of ammonia. Cobalt is susceptible of magnetism, but in a lower degree than steel and nickel. Oxygen combines with cobalt in two pro- portions ; forming the dark blue protoxide, and the black deutoxide. The first dissolves in acids without effervescence. It is procured by igniting gently in a retort the oxide preci- pitated by potash from the nitric 'solution. Proust says, the first oxide consists of 100 metal -f- 19.8 oxygen ; and Rothoff makes the composition of the deutoxide 100 + 36.77. If we call the first 18.5, and the second 37, then the prime equivalent of cobalt will be 5.4 ; and the two oxides will consist of Cobalt, 5.4 100 84.38 Oxygen, 1.0 18.5 15.62 Protox. TWfmr Deutox. 100.00 Cobalt, 5.4 100 73 Oxygen, 2.0 37 27 100 The precipitated oxide of cobalt, washed and gently heated in contact with air, passes into the state of black peroxide. When cobalt is heated in chlorine, it takes fire, and forms the chloride. The iodide, phosphuret, and sulphuret of this metal, have not been much examined. The salts of cobalt are interesting from the remarkable changes of colour which they can exhibit. Their solution is red in the neutral state, but green with a slight excess of acid ; the alkalis occasion a blue-coloured precipitate from the salts of pure cobalt, but reddish- brown when arsenic acid is present ; sulphu- retted hydrogen produces no precipitate, but hydrosulphurets throw down a black powder, soluble in excess of the precipitant ; tincture of galls gives a yellowish-white precipitate ; oxalic acid throws down the red oxalate. Zinc does not precipitate this metal. The sulphate is formed by boiling sulphuric acid on the metal, or by dissolving the oxide in the acid. By evaporation, the salt may be obtained in acicular rhomboidal prisms of a reddish colour. These are insoluble in alco- hol, but soluble in 24 parts of water. It consists, by the analysis of Bucholz, of Expert. Theory. Acid, 26 or 1 prime 5.0 24.4 Protoxide, 30 1 do. 6.4 31.4 Water, 44 8 do. 9. 44.2 100 20.4 See SALT. The nitrate forms prismatic red deliquescent crystals. It is decomposable by gentle ig- nition. The muriate is easily formed by dis- solving the oxide in muriatic acid. The neu- tral solution is blue when concentrated, and red when diluted ; but a slight excess of acid makes it green. According to Klaproth, a solution of the pure muriate forms a sympa- thetic ink, whose traces become blue when the paper is heated ; but if the salt be contaminated with iron, the traces become green. I find that the addition of a little nitrate of copper to the solution forms a sympathetic ink, which by heat gives a rich greenish-yellow colour. When a small quantity of muriate of soda, of magnesia, or of lime, is added to the ink, its traces disappear very speedily on removal from the fire; showing that the vivid green, blue, or yellow colour, is owing to the concentration of the saline traces by heat, and their disap- pearance, to the reabsorption of moisture. At a red heat, the greater part of the muriate sublimes in a grey- coloured chloride. The acetate forms a sympathetic ink, whose traces being heated, become of a dull blue colour. The arseniate of cobalt is found native in a fine red efflorescence, and in crystals. See ORES of Cobalt. A cream-tartrate of cobalt may be obtained in large rhomboidal crystals, by adding the tartrate of potash to cobaltic solutions, and slow evaporation. An ammo- nia-nitrate of cobalt may be formed in red cubical crystals, by adding ammonia in excess to the nitric solution, and evaporating at a very gentle heat. They have an urinous taste, and are permanent in the air. Oxide of cobalt does not appear to be capable of dissolving directly in ammonia, and a combination be- tween the two substances can take place only under the two following circumstances: 1. Either the oxide of cobalt combines with an acid, and in this state forms a double salt with the ammonia, which is also combined with the same acid; as for example, in the carbonate of oxide of cobalt and ammonia ; nitrate of oxide of cobalt and ammonia, c. ; or 2d, when the proportion of acid is insuffi- cient to saturate both the oxide of cobalt and coc 343 COF ihe ammonia. If the above ammoniacal liquid, previously saturated with oxygen, be com- mitted to a rapid spontaneous evaporation, it yields a compound of ammonia with nitric and cobaltic acids, in brown-coloured, apparently four-sided prisms, with square bases- Leopold Gmelin. Annals of Phil N. S- ix. 69- The red oxalate is soluble in an excess of oxalic acid, and hence neutral oxalate of potash is the proper reagent for precipitating cobalt. The phosphate may be formed by double de- composition. It is an insoluble purple powder, which, heated along with eight parts of gela- tinous alumina, produces a beautiful blue pigment, a substitute for ultra-marine. The colouring power of oxide of cobalt on vitri- liable mixtures is greater perhaps than that of any other metal. One grain gives a full blue to 240 grains of glass. Zaffre is a mix- ture of flint powder and an impure oxide of cobalt, prepared by calcination of the ores. Smalt and azure blue are merely cobaltic glass in fine powder. See GLASS. COB ALUS. The demon of mines, which obstructed and destroyed the miners. The church service of Germany formerly contained a form of prayer for the expulsion of the fiend- The ores of the preceding metal being at first mysterious and intractable, were nicknamed cobalt. COCCOLITE- A mineral of a green colour of various shades, which occurs mas- sive ; in loosely aggregated concretions ; and crystallized in six-sided prisms, with two op- posite acute lateral edges, and bevelled on the extremities, with the bevelled plains set on the acute lateral edges; or in four-sided prisms. The crystals are generally rounded on the angles and edges. The internal lustre is vitreous. Cleavage, double oblique an- gular. Fracture uneven. Translucent on the edges. It scratches apatite, but not felspar. Is brittle. Sp. gr. 3-3. It fuses with diffi- culty before the blowpipe. Its constituents are silica 50, lime 24, magnesia 10, alumina 1.5, oxide of iron 7, oxide of manganese 3, loss 4.5. Vauquelin. It occurs along with granular limestone, garnet, and magnetic ironstone, in beds sub- ordinate to the trap formation. It is found at Arendal in Norway, Nericke in Sweden, Barkas in Finland, the Hartz, Lower Saxony, and Spain. COCCULUS INDICUS. The fruit of the menispermum cocculus, a shrub which grows in sand amid rocks on the coasts of Malabar, and other parts of the East Indies. The fruit is blackish, and of the size of a large pea. It contains, 1st, about one-half of its weight of a concrete fixed oil ; 2d, an albu- minous vegeto-animal substance ; 3d, a pecu- liar colouring matter; 4th, one-fiftieth of picrotoxia ; 5th, one-half its weight of fibrous matter j 6th, bimalatc of lime and potash ; 1th, sulphate of potash; 8th, muriate of potash; 9th, phosphate of lime ; 10th, a little iron and silica. It is poisonous ; and is frequently employed to intoxicate or poison fishes. The deleterious ingredient is the PICROTOXIA, which see. COCHINEAL was at first supposed to be a grain, which name it still retains by way of eminence among dyers, but naturalists soon discovered that it was an insect. It is brought to us from Mexico, where the insect lives upon different species of the opuntia. Fine cochineal, which has been well dried and properly kept, ought to be of a grey colour inclining to purple- The grey is owing to a powder which covers it naturally, a part of which it still retains: the purple tinge proceeds from the colour extracted by the water in which it has been killed. Cochi- neal will keep a long time in a dry place. Hellot says, that he tried some one hundred and thirty years old, and found it produce the same effect as new. MM. Pelletier and Caventou have lately found that the very remarkable colouring matter which composes the principal part of cochineal, is mixed with a peculiar animal matter, a fat like common fat, and with dif- ferent salts. The fat having been separated by ether, and the residuum treated with boil- ing alcohol, they allowed the alcohol to cool as they gently evaporated it, and by this means they obtained the colouring matter; but still mixed with a little fat and animal matter. These were separated from it by again dissolving it in cold alcohol, which left the animal matter untouched, and by mixing the solution with ether ; and thus precipitating the colouring matter in a state of great purity, which they have called carminium. It melts at 122 Fahr. becomes puffy, and is decom- posed, but does not yield ammonia. It is very soluble in water, slightly in alcohol, and not at all in ether, unless by the intermediation of fat. Acids change it from crimson, first to bright red, and then to yellow ; alkalis, and, generally speaking, all protoxides turn it violet ; alumina takes it from water. Lake is composed of carminium and alumina. Car- mine is a triple compound of an animal matter, carminium, and an acid which enlivens the colour. The action of muriatic acid in changing the crimson colour of cochineal into a fine scarlet, is similar. Dr. John calls the red colouring matter cochenilin. He says, the insect consists of, Cochenilin, 50-0 Jelly, 10-5 Waxy fat, 10-0 Gelatinous mucus, 14.0 Shining matter/ 14.0 Salts, 1-5 100-0 COFFEE. The seeds of the cojfca ; araUca COH COH are contained in an oval kernel, enclosed in a pulpy berry, somewhat like a cherry. The ripe fruit is allowed slightly to ferment, by which the pulp is more easily detached from the seeds. These are afterwards washed, carefully dried in the sun, and freed from ad- hering membranes by winnowing. Besides the peculiar bitter principle, which we have described under the name Cafein, coffee con- tains several other vegetable products. Ac- cording to Cadet, 64 parts of raw coffee consist of 8 gum, 1 resin, 1 extractive and bitter principle, 3.5 gallic acid, 0.14 albumen, 43.5 fibrous insoluble matter, and 6.86 loss. Her- mann found in 1920 grains of Levant Coffee. Mart. Coffee. Resin, 74 68 Extractive, 320 310 Gum, 130 144 Fibrous matter, 1335 1386 61 12 1920 1920 The nature of the volatile fragrant prin- ciple developed in coffee by roasting, has not been ascertained. The Dutch in Surinam improve the flavour of their coffee by sus- pending bags of it, for two years, in a dry atmosphere. They never use new coffee. Coffee is diuretic, sedative, and a corrector of opium. It should be given as medicine in a strong infusion, and is best cold. In spasmodic asthma it has been particularly serviceable ; and it has been recommended in gangrene of the extremities arising from hard drinking. See CAFEIN. COHESION, or attraction of cohesion, is that power by which the particles of bodies are held together. The absolute cohesion of solids is measured by the force necessary to pull them asunder. Heat is excited at the same time At the iron cable manufactory of Captain Brown, a cylindrical bar of iron, 1^ inch diameter, was drawn asunder by a force of 43 tons. Before the rupture, the bar lengthened about five inches, and the section of fracture was reduced nearly three- eighths of an inch. About this part a degree of heat was generated, which, according to Mr. Barlow of Woolwich, rendered it un- pleasant, if not in a slight degree painful, to grasp tlie bar in the hand. The same thing is shown in a greater degree in wire-drawing. When the force is applied to compress the body, it becomes shorter in the direction of the force, which is called the compression ; and the area of its section at right angles to the force, expands. The cohesion, calculated from the transverse strength, is as near, or perhaps nearer, the real cohesion, than that obtained by pulling the body asunder. The cohesive force of metals is much increased by wire-drawing, rolling, and hammering them. In the eleborate tables of cohesion drawn up by Mr. Thomas Tredgold, and published in the 50th vol. of Tilloch's Magazine, the specific cohesion of plate glass (a pretty uniform body) is denoted by unity. The following table is the result of expe- riments by George Rennie, jun. Esq. pub- lished in the first part of the Phil. Transac- tions for 1818. Mr. Rennie found a cubical inch of the following bodies crushed by the following weights : Ibs. av. Elm, 1284 American pine, 1 606 White deal, .... 1928 English oak, .... 3860 Ditto of five inches long, slipped with, 2572 Ditto, of four inches, ditto, 5147 A prism of Portland stone, two inches long, 805 Ditto statuary marble, , ,. .j> . 3216 Craigleith stone, . . . 8688 Cubes of J inch. Sp. gr. Chalk, 1127 Brick of a pale red colour, 2.085 1265 Roe-stone, Gloucestershire, 1449 Red brick, mean of two trials, 2.168 1817 Yellow face baked Hammer- smith paviors, three times, 2254 Burnt ditto, mean of two trials, 3243 Stourbridge, or fine brick, 3864 Derby grit, a red friable sand- stone, . . . 2.316 7070 Derby grit from another quarry, 2.428 9776 Killaly white freestone, not stra- tified, - .- . 2.423 10264 Portland, . . - 2.428 10284 Craigleith, white freestone, 2.452 12346 Yorkshire paving, with the strata, 2.S07 1 2856 Ditto, against the strata, 2.507 12856 White statuary marble, not veined, ' 1.760 23632 Bramley-Fall sandstone, near Leeds, with strata, - 2.50613632 Ditto, against strata, 2.506 13632 Cornish granite, 2.662 14302 Dundee sandstone, or breccia, two kinds, 2.530 14918 A two inch cube of Portland, 2.423 14918 Craiglieth, with strata, 2.452 15560 Devonshire red marble, varie- gated, 16712 Compact limestone, 2.584 17354 Peterhead granite, hard close- grained, ... 18636 Black compact limestone, Li- merick, - 2.598 19924 Purbeck, . 2.599 20610 Black Brabant marble, 2.697 20742 Very hard freestone, - 2.52821254 White Italian veined marble, 2.726 21783 Aberdeen granite, blue kind, 2.625 24556 COL 345 COL Cubes of different metals of fth inch were crushed by the following weights: Ibs.av. Cast iron, .... 9773 Cast copper, 7318 Fine yellow brass, 10304 Wrought copper, 6440 Cast tin, 966 Cast lead, .... 483 Bars of different metals, six inches long, and a quarter of an inch square, were suspended by nippers, and broken by the following weights : Cast iron, horizontal, . > .. j ."::, 1166 Ditto, vertical, . . .,> i*w 1218 Cast steel, previously tilted, . . 8391 Blistered steel, reduced by the hammer, 8322 Shear steel ditto, . . . 7977 Swedish iron ditto, .:-,*< . 4504 English iron ditto, . . . 3492 Hard gun metal, mean of two trials, 2273 Wrought copper, reduced by hammer, 2112 Cast copper, . . . . 1192 Fine yellow brass, * *M.>* -- . , 1123 Ibs.av, Cast tin, 296 Cast lead, 114 For the experiments on the twist of bars we must refer to the paper. The strengths of Swedish and English iron do not bear the same proportion to each other in these experiments, that they do when we compare the trials of Count Sickingen with those made at Woolwich, of which an account was given in the Annals of Philosophy, vii. 320. From that comparison, the proportional strengths were as follows : English iron, . 348-38 Swedish iron, . 549-25 But from Mr. Rennie's experiments, the pro- portional strengths are : English iron, . 348-38 Swedish iron, . 449-34 A very material difference, which ought to be attended to. The following Table contains a view of some former experiments, on the cohesive strengths or tenacities of bodies. A wire one-tenth inch of zinc breaks with 26 pounds. Mechenbroek. Do. Do. Do. Do. Do. Do. Do. A cylinder 1 inch lead tin copper brass silver iron gold iron V* 49^ 299* 360 370 450 500 63320 Emerson. do. do. do. do. do. do. Rumford. According to Sickingen, the relative cohe- sive strengths of the metals are as follows : Gold, 150955 Silver, 190771 Platina, 262361 Copper, 304696 Soft iron, 362927 Hard iron, 559880 A wire of iron 0-078 or ~ of an inch, will just support 549-25 pounds. Emerson's num- ber for gold is excessively incorrect. In gene- ral, iron is about 4 times stronger than oak, and 6 times stronger than deal. COHOBATION. The continuous redis- tillation of the same liquid from the same materials. COLCHICUM AUTUMNALE. A me- dicinal plant, the vinous infusion of whose root has been shewn by Sir E. Home to possess specific powers of alleviating gout, similar to those of the empirical preparation called Eau Mcdicinale D Husson. The se- diment of the infusion ought to be removed by filtration, as it occasions gripes, sickness, and vomiting. COLCOTHAR. The brown-red oxide of iron, which remains after the distillation of the acid from sulphate of iron : it is used for polishing glass and other substances by artists, who call it crocus, or crocus martis. COLD. The privation of heat. Soe CA- LORIC, CONGELATION, and TEMPERA- TURE. COLOCYNTHINE. Colocynth treated with alcohol yields the bitter substance much purer than when water is used. The alcoholic solution evaporated, yields a very brittle sub- stance, of a gold yellow colour ; which when put into cold water produces a solution, while white opaque filaments remain, which ulti- mately form a soft semi-transparent yellow mass resembling some resins. This substance, containing the bitterness of the colocynth, appears to be a peculiar principle. It is very soluble in alcohol, far less so in water, but affords with it, a solution of extreme bit- terness and frothing on agitation. Vauquclin, Journ. de Pharmacie for 1824, 416. COLOPHONITE. A mineral of a black- ish or yellowish-brown, or orange-red colour ,- of a resino-adamantine lustre ; and conchoidal fracture. Its sp. gr. is 4.0. It consists of silica 35, alumina 13.5, lime 29.0, magnesia 6.5, oxide of iron 7.5, oxide of manganese 4.75, and oxide of titanium 0.5. It occurs massive, in angulo-granular concretions, and in rhomboidal dodecahedrons, whose surfaces COM 346 COM have a melted appearance. It is the resinous garnet of Haiiy and Jameson. It is found in magnetic ironstone at Arendal in Norway. It occurs also in Piedmont and Ceylon. COLOPHONY. Colophony, or black resin, is the resinous residuum after the distil- lation of the light oil, and thick dark reddish balsam, from turpentine. COLOURING MATTER. See DYE- ING. COLUMBITE. A mineral found at Had- dam in Connecticut. It occurs in small amor- phous masses, and in minute crystals, dissemi- nated in a granitic aggregate. Colour greyish- black; opaque; fracture imperfectly con- choidal. Scratches glass, but does not strike fire with steel. Powder dark brown : sp. gr. 5-9. Borax dissolves it very slowly at the blowpipe into a pale yellowish glass. The form of the crystal is a compressed rectangular prism, truncated on the lateral edges ; or a four- sided pyramid. The columbite is an ore of the Tantalum of Berzelius, or Columbium of Hatchett. See Ores of Tantalum. COLUMBIUM. If the oxide of colum- bium, described under ACID (CoLUMBic), be mixed with charcoal, and exposed to a violent heat in a charcoal crucible, the metal columbium will be obtained. It has a dark grey colour ; and when newly abraded, the lustre nearly of iron. Its sp. gr. when in ag- glutinated particles, was found by Dr. Wol- laston to be 5.GI. These metallic grains scratch glass, and are easily pulverized. Nei- ther nitric, muriatic, nor nitro-muriatic acid, produces any change in this metal, though digested on it for several days. It has been alloyed with iron and tungsten. See ACID (COLUMBIC). COMBINATION; the intimate union of the particles of different substances by che- mical attraction, so as to form a compound possessed of new and peculiar properties. See ATTRACTION, EQUIVALENT, and GAS. COMBUSTIBLE. A body which, in its rapid union with others, causes a disengage- ment of heat and light. To determine this rapidity of combination, or intensity of che- mical action, a certain elevation of temperature is necessary, which differs for every different combustible. This difference thrown into a tabular form would constitute their scale of asccndibUity, or degree of accension. Stahl adapted, and refined on the vulgar belief of the heat and light coming from the combustible itself; Lavoisier advanced the op- posite and more limited doctrine, that the heat and light proceeded from the oxygenous gas in air and other bodies, which he regarded as the true pabulum of fire. Stahl's opinion is perhaps more just than Lavoisier's ; for many combus- tibles burn together, without the presence of oxygen, or of any analogous fancied supporters ; as chlorine, and the adjuncts to oxygen, have been unphilosophically called. Sulphur, hy- drogen, carbon, and azote, arc as much entitled to be styled supporters, as oxygen and chlo- rine, for potassium burns vividly in sulphur- etted hydrogen, and in prussine, and most of the metals burn with sulphur alone. Heat and light are disengaged, with a change of properties, and reciprocal saturation of the combining bodies. All the combustible gases are certainly capable of affording heat, to the degree of incandescence, as is shown by their mechanical condensation. Sound logic would justify us in regarding oxygen, chlorine, and iodine, as in reality combustible bodies, perhaps more so than those substances vulgarly called combustible. Ex- periments with the condensing syringe, and the phenomena of the decomposition of cu- chlorine, prove that light as well as heat may be afforded by oxygen and chlorine. If the body, therefore, which emits, or can emit, light and heat in copious streams, by its action on others, be a combustible, then chlorine and oxygen merit that designation as much as charcoal and sulphur. Azote is declared by the ex- pounders of the Lavoisierian creed to be a sim- ple incombustible. Yet its mechanical con- densation proves that it can afford, from its own resources, an incandescent heat ; and with chlorine, iodine, and metallic oxides all in- combustibles on the antiphlogistic notion, it forms compounds possessed of combustible properties, in a pre-eminent and a tremendous degree of concentration. It is melancholy to reflect with what easy credulity the fictions of the Lavoisierian faith have been received and propagated by chemical compilers, sometimes sufficiently incredulous on subjects of rational belief. See the next Article. The electric polarities unquestionably show, what no person can wish to deny, that between oxygen, chlorine, iodine, on one hand, and hydrogen, charcoal, sulphur, phosphorus, and the metals, on the other, there exist striking differences. The former are attracted by the positive pole, the latter by the negative, in voltaic arrangements. But still nothing de- finitive can be inferred from this fact ; because in the actions of what are called combustibles on each other, without the presence of the other class, we have an exhibition of opposite electrical polarities. Sulphur and metallic plates, by mutual friction or mere contact, produce electrical changes, which apparently prove that sulphur should be ranked along with oxygen, chlorine, and acids, apart from combustibles, whose polarities are negative. Sulphuretted hydrogen, in its electrical relations to metals, ranks also with oxygen and acids. How vague and fallacious a rule of classifica- tion electrical polarity would afford, may be judged of from the following unquestionable facts: "Among the substances that combine chemically, all those, the electrical energies of which are well known, exhibit opposite states; thus copper and zinc, gold and quicksilver, COM 347 COM sulphur and the metals, the acid and alkaline substances, afford apposite instances. In the voltaic combination of diluted nitrous acid, zinc and copper, as is well known, the side of the zinc exposed to the acid is positive. But in combinations of zinc, water, and diluted nitric acid, the surface exposed to the acid is nega- tive ; though if the chemical action of the acid on the zinc had been the cause of the effect, it ought to be the same in both cases." On some Chemical Agencies of Electricity, lySir H. Davy. Phil. Trans. 1807- Combustibles have been arranged into sim- ple and compound. The former consist of hydrogen, carbon, boron, sulphur, phosphorus, and nitrogen, besides all the metals. The latter class comprehends the hydrurets, car- burets, sulphurets, phosphorets, metallic alloys, and organic products. When the pure oxides of iron, cobalt, or nickel are reduced by hydrogen gas, at tem- peratures but very little above that of boiling mercury, metals are obtained, which, when allowed to cool in the hydrogen gas, inflame spontaneously by exposure to the atmosphere. If the reduction has been effected at a red heat, this does not take place. When the same oxides are mixed with a little alumina, the metals obtained, as before, inflame spontaneously in the atmosphere, even though the heat used has been that of redness, and yet from the quantity of oxygen disen- gaged, it has been evident that the alumine has not been de-oxidized. When a metal thus competent to inflame in the air is heated in carbonic acid gas, it loses its peculiar property, but resumes it on being heated once more in hydrogen gas, and allowed to cool as before. The hydrogen, however, is not the cause of this inflammation ; for when oxalate of iron is heated in a vessel with a narrow neck, so that the acid may be decomposed, and the whole allowed to cool, the metallic iron-pow- der obtained inflames spontaneously in the atmosphere. No other metal but the three mentioned have presented this phenomenon. With these effects may possibly be ranged that observed by Dr. Gobel, as produced by the residuum left after igniting the tartrate of lead in close vessels. Annales des Mines, xii. 210. COMBUSTION. The disengagement of heat and light which accompanies chemical combination. It is frequently made to be sy- nonymous with inflammation, a term which might be restricted, however, to that peculiar species of combustion in which gaseous matter is burned. Ignition is the incandescence of a body, produced by extrinsic means, without change of its chemical constitution. Beccher and Stahl, feeling daily the neces- sity of fire to human existence, and astonished with the metamorphoses which this 'power seemed to cause charcoal, sulphur, and metals to undergo, came to regard combustion as/ did single phenomenon of chemistry. Under this impression Stahl framed his chemical system, the Theoria Chemicr Dogmatlccc, a title cha- racteristic of the spirit with which it was in- ^ culcated by chemical professors, as the infalli- ble code of their science for almost a century. When the discoveries of Scheele, Cavendish, and Priestley, had fully demonstrated the es- sential part which air played in many instances of combustion, the French school made a small modification of the German hypothesis. In- stead of supposing, with Stahl, that the heat and light were occasioned by the emission of a common inflammable principle from the combustible itself, Lavoisier and his associates dexterously availed themselves of Black's hy- pothesis of latent heat, and maintained, that the heat and light emanated from the oxygen- ous air, at the moment of its union or fixation with the inflammable basis. How thoroughly the chemical mind has been perverted by these conjectural notions, our systems of chemistry abundantly prove. Dr. Robison, in his preface to Black's Lec- tures, after tracing, with perhaps superfluous zeal, the expanded ideas of Lavoisier to the neglected germs of Hooke and Mayhow, says, " This doctrine concerning combustion, the great, the characteristic phenomenon of che- mical nature, has at last received almost uni- versal adoption, though not till after consider- able hesitation and opposition ; and it has made a complete revolution in chemical science." The French theory of chemistry, as it was called, or hypothesis of combustion, as it should have been named, was for some time classed in certainty with the theory of gra- vitation. It is vanishing with the phantoms of the day; but the sound logic, the pure candour, the numerical precision of inference, which characterize Lavoisier's Elements, will cause his name to be held in lasting admira- tion. It was the rival logic of Sir H. Davy, aided by his unrivalled felicity of investigation, which first recalled chemistry from the labyrinths of fancy, to the more arduous but far more pro- fitable career of reason. His researches on combustion and flame, already rich in bless- ings to mankind, would alone place him in the first rank of scientific genius. I shall give a somewhat copious account of them, since by some fatality it has happened, that in our most extensive system, where so many pages are devoted to the reveries of ancient chemists, the splendid and useful truths made known by the great chemist of England have been almost overlooked. Whenever the chemical forces which deter- mine either composition or decomposition are energetically exercised, the phenomena of com- bustion, or incandescence, with a change of properties, are displayed. The distinction, therefore, between supporters of combustion COM 348 COM and combustibles, on which some late systems are arranged, is frivolous and partial. In fact, one substance frequently acts in both capa- cities, being a supporter apparently at one time, and a combustible at another. But in both cases the heat and light depend on the same cause, and merely indicate the energy and rapidity with which reciprocal attractions are exerted. Thus, sulphuretted hydrogen is a combus- tible with oxygen and chlorine ; a supporter with potassium. Sulphur, with chlorine and oxygen, has been called a combustible basis ; with metals it acts the part of a supporter ; for incandescence and reciprocal saturation result. In like manner, potassium unites so power- fully with arsenic and tellurium as to produce the phenomena of combustion. Nor can we ascribe the appearances to extrusion of latent heat in consequence of condensation of vo- lume. The protoxide of chlorine, a body de- stitute of any combustible constituent, at the instant of decomposition evolves light and heat with explosive violence ; and its volume becomes one-6fth greater. Chloride and iodide of azote, compounds alike destitute of any in- flammable matter, according to the ordinary creed, are resolved into their respective ele- ments with tremendous force of inflammation ; and the first expands into more than 600 times its bulk. Now, by the prevailing hypothesis of latent caloric, instead of heat and light, a prodigious cold ought to accompany such an expansion. The chlorates and nitrates, in like manner, treated with charcoal, sulphur, phosphorus, or metals, deflagrate or detonate while the volume of the combining substances is greatly enlarged. The same thing may be said of the nitrogurets of gold and silver. ' In truth, the combustion of gunpowder, a pheno- menon too familiar to mankind, should have been a bar to the reception of Lavoisier's hy- pothesis of combustion. The subterfuges which have been adopted in order to reconcile them do not merit a detail. From the preceding facts, it is evident, 1st, That combustion is not necessarily dependent on the agency of oxygen ; 2d, That the evo- lution of the heat is not to be ascribed simply to a gas parting with its latent store of that ethereal fluid, on its fixation or combustion ; and, 3dly, " That no peculiar substance or form of matter is necessary for producing the effect, but that it is a general result of the ac- tions of any substances possessed of strong chemical attractions, or different electrical re- lations, and that it takes place in all cases in which an intense and violent motion can be conceived to be communicated to the corpus- cles of bodies." All chemical phenomena indeed may be justly ascribed to motions among the ultimate particles of matter, tending to change the con- stitution of die mass. It was fashionable for a while to attribute the caloric evolved in combustion, to a di- minished capacity for heat of the resulting substance. Some phenomena, inaccurately observed, gave rise to this generalization. On this subject I shall content myself with stating the conclusions to which MM. Dulong and Petit have come, in consequence of their own recent researches on the laws of heat, and those of Berard and Delaroche. 4k We may likewise," say these able chemists, " deduce from our researches another very important consequence for the general theory of chemical action, that the quantity of heat developed at the instant of the combination of bodies has no relation to the capacity of the elements ; and that, in the greatest number of cases, this loss of heat is not followed by any diminution in the capacity of the compounds formed. Thus, for example, the combination of oxy- gen and hydrogen, or of sulphur and lead, which produces so great a quantity of heat, occasions no greater alteration in the capacity of water, or of sulphuret of lead, than the combination of oxygen with copper, lead, sil- ver, or of sulphur with carbon, produces in the capacities of the oxides of these metals, or of carburet of sulphur." " We conceive, that the relations which we have pointed out be- tween the specific heats of simple bodies, and of those of their compounds, prevent the pos- sibility of supposing, that the heat developed in chemical actions owes its origin merely to the heat produced by change of state, or to that supposed to be combined with the mate- rial molecules." Annalcs de Chimic et Phy- sique, x. Mr. Dalton, in treating of the constitution of elastic fluids, lays it down as an axiom, that diminution of volume is the criterion of chemical affinity being exercised; and hence maintains, that the atmospheric air is a mere mixture. Thus, also, the extrication of heat from chemical union has been usually referred to the condensation of volume. The following examples will show the fallacy of such hypo- theses. 1. Chlorine and hydrogen mixed, ex- plode by the sunbeam, electric spark, or in- flamed taper, with the disengagement of much heat and light ; and the volume of the mix- ture, which is greatly enlarged at the instant of combination, suffers no condensation after- wards. Muriatic acid gas, having the mean density of its components, is produced. 2. When one volume of olefiant gas and one of oxygen are detonated together, three and a half gaseous volumes result, the greater part of the hydrogen remains untouched, and a vo- lume and a half of carbonic oxide is formed, with about ]-10th of carbonic acid. 3. The following experiments of M. Gay Lussac on liquid combinations are to the same purpose. 1. A saturated solution of nitrate of ammo- nia, at the temperature of 61, and of the density 1.302, was mixed with water in U>e proportion of 44.05 to 33 7'>. The tempera- COM 349 COM ture of the mixture sank 80 ; but the density at 61 was 1.159, while the mean density was only 1.151. 2. On adding water to the pre- ceding mixture, in the proportion of 33.64 to 39.28, the temperature sank 3.4, while the density continued 0.003 above the mean. Other saline solutions presented the same re- sult, though none to so great a degree. That the internal motions which accom- pany the change in the mode of combination, independent olf change of form, occasion the evolution of heat and light, is evident from the following observations of Berzelius : In the year 1811, when he was occupied with ex- amining the combinations of antimony, he dis- covered, accidentally, that several metalline antimoniates, when they begin to grow red- hot, exhibit a sudden appearance of fire, and then the temperature again sinks to that of the surrounding combustibles. He made nu- merous experimeats to elucidate the nature of this appearance, and ascertained that the weight of the salt was not altered, and that the ap- pearance took place without the presence of oxygen. Before the appearance of fire, these salts are very easily decomposed, but after- wards they are attacked neither by acids nor alkaline leys a proof that their constituents are now held together by a stronger affinity, or that they are more intimately combined. Since that time he has observed these appear- ances in many other bodies, as, for example, in green oxide of chromium, the oxides of tan- talum and rhodium. (See CHROMIUM). Mr. Edmund Davy found, that when a neutral solution of platinum was precipitated by hydrosulphuret of potash, and the preci- pitate dried in air deprived of oxygen, a black compound was obtained, which when heated out of the contact of air, gave out sulphur, and some sulphuretted hydrogen gas, while a combustion similar to that in the formation of the metallic sulphurets appeared, and com- mon sulphuret of platinum remained behind. When we heat the oxide of rhodium, obtained from the soda-muriate, water first comes over ; and on increasing the temperature, combustion takes place, oxygen gas is suddenly disengaged, and a suboxide of rhodium remains behind. The two last cases are analogous to that of the protoxide of chlorine, the euchlorine of Sir H. Davy. Gadolinite, the silicate of yttria, was first observed by Dr. WolJaston to dis- play a similar lively incandescence. The variety of this mineral with a glassy fracture, answers better than the splintery variety. It is to be heated before the blowpipe, so that the whole piece becomes equally hot At a red heat it catches fire. The colour becomes greenish-grey, and the solubility in acids is destroyed. Two small pieces of gadolinite, one of which had been heated to redness, were put in aqua regia ; the first was dissolved in a few hours ; the second was not attacked in two months. Finally, Sir H. Davy ob- served a similar phenomenon on heating hy- drate of zirconia. The verbal hypothesis of thermoxygen by Brugnatelli, with Dr. Thomson's supporters, partial supporters, and semicombustion, need not detain us a moment from the substantial facts, the noble truths, first revealed by Sir H. Davy, concerning the mysterious process of combustion. Of the researches which brought them to light it has been said, without any hyperbole, that " if Bacon were to revisit the earth, this is exactly such a case as we should choose to place before him, in order to give him, in a small compass, an idea of the ad- vancement which philosophy has made since the time when he had pointed out to her the route which she ought to pursue." The coal mines of England, alike essential to the comfort of her population and her finan- cial resources, had become infested with fire- damp, or inflammable air, to such a degree as to render the mutilation and destruction of the miners, by frequent and tremendous explo- sions, subjects of sympathy and dismay to the whole nation. By a late explosion in one of the Newcastle collieries, no less than one hun- dred and one persons perished in an instant ; and the misery heaped on their forlorn families, consisting of more than three hundred persons, is inconceivable. To subdue this gigantic power was the task which Sir H. Davy as- signed to himself ; and which, had his genius been baffled, the kingdom could scarcely hope to see achieved by another. But the stubborn forces of nature can only be conquered, as Lord Bacon justly pointed out, by examining them in the nascent state, and subjecting them to experimental interrogation, under every di- versity of circumstance and form. It was this investigation which first laid open the hither- to unseen and inaccessible sanctuary of Fire. As some attempts, however, have been made, to insinuate that Sir H. Davy stole the germ of his discoveries from the late Mr. Tennant, it may be proper to preface the account of them by the following extract from " Resolutions of a Meeting held for considering the Facts rela- ting to the Discovery of the Lamp of Safety." " Soho Square, Nov. 20. 1817- 3d. That Sir H. Davy not only disco- vered, independently of all others, and without any knowledge of the unpublished experiments of the late Mr. Tennant on Flame, the princi- ple of the non-communication of explosions through small apertures, but that he has also the sole merit of having first applied it to the very important purpose of a safety-lamp, which has evidently been imitated in the latest lamps of Mr. George Stephen son. (Signed) Joseph Banks, P. R. S. William J. Brande. Charles Hatchett. William Hyde Wollaston. Thomas Young." COM 350 COM See the whole document in Tilloch's Magazine, vol. 50. p. 387. The phenomena of combustion may be con- veniently considered under six heads : I st, The temperature necessary to inflame different bodies. 2d, The nature of flame, and the re- lation between the light and heat which com- pose it. 3d, The heat disengaged by different combustibles in burning. 4th, The causes which modify and extinguish combustion, and of the safe- lamp. 5th, Invisible combustion. 6th, Practical inferences. :$-" }st, Of the temperature necessary to in- flame different bodies. 1st, A simple experi- ment shows the successive combustibilities of the different bodies. Into a long bottle with a narrow neck, introduce a lighted taper, and let it burn till it is extinguished. Carefully stop the bottle, and introduce another lighted taper. It will be extinguished before it reaches the bottom of the neck. Then introduce a small tube, containing zinc and dilute sulphuric acid at the aperture of which the hydrogen is in- flamed. The hydrogen will be found to burn in whatever part of the bottle the tube is placed. After the hydrogen is extinguished, in- troduce lighted sulphur. This will burn for some time ; and after its extinction phospho- rus will be as luminous as in the air, and, if heated in the bottle, will produce a pale yel- low flame of considerable density. Phosphorus is said to take fire when heated to 150 and sulphur to 550. Hydrogen in- flames with chlorine at a lower temperature than with oxygen. By exposing oxygen and hydrogen, confined in glass tubes, to a very dull red (about 800 F.) they explode. When the heat was about 700 F. they combined ra- pidly with a species of silent combustion. A mixture of common air and hydrogen was in- troduced into a small copper tube, having a stopper not quite tight ; the copper tube was placed in a charcoal fire ; before it became vi- sibly red-hot an explosion took place, and the stopper was driven out. We see, therefore, that the inflaming temperature is independent of compression or rarefaction. The ratio of the combustibility of the differ- ent gaseous matters is likewise, to a certain extent, as the masses of heated matters re- quired to inflame them. Thus, an iron wire 1 -40th of an inch, heated cherry-red, will not inflame olefiant gas, but it will inflame hydro- gen gas. A wire of l-8th, heated to the same degree, will inflame olefiant gas. But a wire -gfo of an inch must be heated to whiteness to inflame hydrogen, though at a low red heat it will inflame biphosphuretted gas. Yet wire of l-40th, heated even to whiteness, will not in- flame mixtures of fire-damp. Carbonic oxide inflames in the atmosphere when brought into contact with an iron wire heated to dull red- ness ; whereas carburetted hydrogen is not in- flammable, unless the iron is heated to white- ness, to as to burn with sparks. These circumstances will explain why a mesh of wire, so much finer or smaller, is re- quired to prevent the explosion from hydrogen and oxygen from passing ; and why so coarse a texture and wire are sufficient to prevent the explosion of the fire-damp, fortunately the least combustible of all the inflammable gases known. The flame of sulphur, which kin- dles at so low a temperature, will exist under refrigerating processes, which extinguish the flame of hydrogen and all carburetted gases. Let the smallest possible flame be made by a single thread of cotton immersed in oil, and burning immediately upon the surface of the oil. It will be found to yield a flame about l-30th of an inch in diameter. Let a fine iron wire of -^^ of an inch, made into a ring of l-40th of an inch diameter, be brought over the flame. Though at such a distance, it will instantly extinguish the flame, if it be cold : but if it be held above the flame, so as to be slightly heated, the flame may be passed through it without being extinguished. That the effect depends entirely on the power of the metal to abstract the heat of flame is shown by bringing a glass capillary ring of the same diameter and size over the flame. This being a much worse conductor of heat, will not, even when cold, extinguish it. If its size, however, be made greater, and its circumfe- rence smaller, it will act like the metallic wire, and require to be heated to prevent it from extinguishing the flame. Now a flame of sulphur may be made much smaller than that of hydrogen ; one of hydrogen may be made much smaller than that of a wick fed with oil ; and that of a wick fed with oil smaller than that of carburetted hydrogen. A ring of cool wire, which instantly extinguishes the flame of carburetted hydrogen, diminishes but slightly the size of a flame of sulphur of the same dimensions. By the following simple contrivance, we may determine the relative facility of burning, among different combustibles. Prepare a se- ries of metallic globules of different sizes, by fusion at the end of iron wires, and light a series of very minute flames of different bodies all of one size. If a globule l-20th of an inch diameter be brought near an oil flame of 1 -30th in diameter, it will extinguish it, when cold, at the distance of a diameter. The size of the spherule adequate to the extinction of the par- ticular flame will be a measure of its combus- tibility. If the globule be heated, however, the distance will diminish at which it produces extinction. At a white heat, the globule, in the above instance, does not extinguish it by actual contact, though at a dull red heat it immediately produces the effect. 2d, Of the nature of flame, and of the re- lotion between the light and the heat which compose it. The flame of combustible bodies may, in all cases, be considered as the com- bustion of un explosive mixture of inflam- COM 351 COM inable gas, or vapour, with air. It cannot be regarded as a mere combustion, at the surface of contact, of the inflammable matter. This fact is proved by holding a taper, or a piece of burning phosphorus, within a large flame made by the combustion of alcohol. The ilame of the taper, or of the phosphorus, will appear in the centre of the other flame, prov- ing that there is oxygen even in its interior part. When a wire- gauze safe-lamp is made to burn in a very explosive mixture of coal gas and air, the light is feeble, and of a pale colour. Whereas the flame of a current of coal gas burnt in the atmosphere, as is well known by the phenomena of the gas lights, is extremely brilliant It becomes, therefore, a problem of some interest, " Why the com- bustion of explosive mixtures, under different circumstances, should produce such different appearances ?" In reflecting on the circum- stances of these two species of combustion, Sir H. Davy was led to imagine that the cause of the superiority of the light of the stream of coal gas, might be owing to the decomposition of a part of the gas, towards the interior of the flame, where the air was in the smallest quan- tity, and the deposition of solid charcoal, which first by its ignition, and afterwards by its combustion, increased, in a high degree, the intensity of the light. The following ex- periments shew, that this is the true solution of the problem. If we hold a piece of wire-gauze, of about 900 apertures to the square inch, over a stream of coal gas issuing from a small pipe, and if we inflame the gas above the wire-gauze left almost in contact with the orifice of the pipe, it burns with its usual bright light. On raising the wire-gauze so as to cause the gas to be mixed with more air before it inflames, the light becomes feebler, and at a certain dis- tance the flame assumes the precise character of that of an explosive mixture burning within the lamp. But though the light is so feeble in this case, the heat is greater than when the light is much more vivid. A piece of wire of platina, held in this feeble blue flame, be- comes instantly white-hot. On reversing the experiment, by inflaming a stream of coal gas, and passing a piece of wire-gauze gradually from the summit of the flame to the orifice of the pipe, the result is still more instructive. li is found that the apex of the flame, intercepted by the wire- gauze, affords no solid charcoal ; but in pass- ing it downwards, solid charcoal is given off in considerable quantities, and prevented from burning by the cooling agency of the wire- gauze. At the bottom of the flame, where the gas burned blue, in its immediate contact with the atmosphere, charcoal ceased to be deposited in visible quantities. The principle of the increase of the bril- liancy and density of flame, by the production and ignition of solid matter, appears to admit of many applications. Thus, defiant gas gives the most brilliant white light of all combustible gases, because, as we learn from Berthollet's experiments, related under carburetted hydro- gen, at a very high temperature it deposits a very large quantity of solid carbon. Phos- phorus, which rises in vapour, at common temperatures, and the vapour of which com- bines with oxygen at those temperatures, is always luminous; for each particle of acid formed must, there is every reason to believe, be white-hot. So few of these particles, how- ever, exist in a given space, that they scarcely raise the temperature of a solid body exposed to them, though, as in the rapid combustion of phosphorus, where immense numbers are ex- isting in a small space, they produce a most intense heat. The above principle readily explains the appearances of the different parts of the flames of burning bodies, and of flame urged by the blowpipe. The point of the inner blue flame, where the heat is greatest, is the point where the whole of the charcoal is burned in its gaseous combinations, without previous depo- sition. It explains also the intensity of the light of those flames in which Jived solid matter is produced in combustion, such as the flame of phosphorus and of zinc in oxygen, &c. and of potassium in chlorine, and the feebleness of the light of those flames in which gaseous and volatile matter alone is produced, such as those of hydrogen and of sulphur in oxygen, phosphorus in chlorine, &c. It offers means of increasing the light of certain burning substances, by placing in their flames even incombustible substances. Thus the intensity of the light of burning sulphur, hydrogen, carbonic oxide, &c. is wonderfully increased by throwing into them oxide of zinc r or by placing in them very fine amianthus or metallic gauze. It leads to deductions concerning the che- mical nature of bodies, and various phenomena of their decomposition. Thus ether burns with a flame which seems to indicate the pre- sence of olefiant gas in that substance. Alco- hol burns with a flame similar to that of a mixture of carbonic oxide and hydrogen. Hence the first is probably a binary compound of olefiant gas and water, and the second of carbonic oxide and hydrogen. When proto- chloride of copper is introduced into the flame of a candle or lamp, it affords a peculiar dense and brilliant red light, tinged with green and blue towards the edges, which seems to depend upon the chlorine being separated from the cop- per by the hydrogen, and the ignition and com- bustion of the solid copper and charcoal. Similar explanations may be given of the phenomena presented by the action of other combinations of chlorine on flame ; and it is probable, in many of those cases, when the co- lour of flame is changed by the introduction of COM 352 COM incombustible compounds, that the effect de- pends on the production, and subsequent igni- tion or combustion, of inflammable matter from them. Thus the rose coloured light given to flame by the compounds of strontium and cal- cium, and the yellow colour given by those of barium, and the green by those of boron, may depend upon a temporary production of these bases, by the inflammable matter of the flam Dr. Clarke's experiments on the reduction of barytes, by the hydroxygen lamp, is favourable to this idea. Nor should any supposed inade- quacy of heat in ordinary flame prevent us from adopting this conclusion. Flame, or gaseous matter, heated so highly as to be luminous, pos- sesses a temperature beyond the white heat of solid bodies, as is shown by the circumstance, that air not luminous will communicate this degree of heat. This is proved by a simple experiment. Hold a fine wire of platinum about l-20th of an inch from the exterior of the middle of the flame of a spirit-lamp, and con- ceal the flame by an opaque body . The wire will become white-hot in a space where there is no visible light. The real temperature of visible flame is perhaps as high as any we are acquainted with. Mr. Tennant used to illus- trate this position, by fusing a small filament of platinum in the flame of a common candle. These views will probably offer illustrations of electrical light The voltaic arc of flame from the great battery differs in colour and intensity, according to the substances employed in the circuit, and is infinitely more brilliant and dense with charcoal than with any other substance. May not this depend, says Sir H. Davy, upon particles of the substances sepa- rated by the electrical attractions ? And the par- ticles of charcoal, being the lightest among solid bodies (as their pi inie equivalent shows), and the least coherent, would be separated in the largest quantities. The heat of flames may be actually dimi- nished by increasing their light (at least the heat communicable to other matter), and vice versa- The flame from combustion, which produces the most intense heat amongst those which have been examined, is that of a mix- ture of oxygen and hydrogen compressed in Newmann's blowpipe apparatus. (See BLOW- PIPE). This flame is hardly visible in bright day-light, yet it instantly fuses the most re- fractory bodies ; and the light from solid bodies ignited in it is so vivid as to be painful to the eye. This application certainly originated from Sir H. Davy's discovery, that the explo- sion from oxygen and hydrogen would not com- municate through very small apertures, and he himself first tried the experiment with a fine glass capillary tube. The flame was not visi- ble at the end of this tube, being overpowered by the brilliant star of the glass, ignited at the aperture. 3. Qf the heat disengaged by different com- bustibles in the act of burning. Lavoisier, Crawford, Dalton, and Rumford, in succession, made experiments to determine the quantity of heat evolved in the combustion of various bodies. The apparatus used by the last was perfectly simple, and perhaps the most precise of the whole. The heat was conducted by flattened pipes of metal, into the heart of a body of water, and was measured by the tem- perature imparted. The following is a general table of results : Substances burned, l Ib. Oxygen consumed in Ibs. Ice melted in Ibs. Lavoisier. Crawford. Dalton. Rumford. Hydrogen, 7-5 295-6 480 320 Carburetted hydrogen, 4 85 Olefiant gas, 3-50 88 Carbonic oxide. 0-58 25 Olive oil, ' 3-00 149 89 104 94-07 Rape oil, - 3-0 124-10 Wax, . - 3.0 133 97 104 126-24 Tallow, . 3-0 96 104 111-58 Oil of turpentine, Alcohol, 2-0? 60 58 67-47 Ether, sulphuric, 3 62 107-03 Naphtha, 97-83 Phosphorus, 1-33 100 60 Charcoal, ^ . " . 2-66 96-5 69 40 Sulphur, 1-00 20 Camphor, /, 4 r 70 Caoutchouc, 42 The discrepancies in the preceding table are sufficient to show the necessity of new experi- ments on the subject. Count Rumford made a series of experiments on the heat given out COM 353 COM during the combustion of different woods. He found that one pound of wood by burning, produced as much heat as would have melted from about 34 to 54 pounds of ice. The average quantity is about 40. MM. Clement and Desormes find that woods give out heat in the ratio of their respective quantities of car- bon ; which they state to be equal to one half of their total weight. Hence, they assign 48 pounds as the quantity of ice melted, in burn, ing one of wood. In treating of acetic acid and carbon, I have already taken occasion to state, that they appear probably to overrate the proportion of carbon in woods. The preceding table is incorrectly given in several respects by our systematic writers ; Dr. Thomson, for example, states that 1 pound of hydrogen consumes only 6 pounds of oxygen, though the saturating proportion assigned by him is 8 pounds. The proportions of oxygen consumed by olive oil, phosphorus, charcoal, and sulphur, are all in like manner erroneous. In vol. i p. 184, of Dr. Black's Lectures, we have the following notes. " 100 pounds weight of the best Newcastle coal, when ap- plied by the most judiciously constructed fur- nace, will convert about l wine hogsheads of water, into steam that supports the pressure of the atmosphere." 1-| hogsheads of water weigh about 790 pounds. Hence, 1 part of coal will convert nearly 8 parts of water into steam. Count Rumford says, that the heat generated in the combustion of 1 pound of pit- coal, would make 36-^ pounds of ice-cold water boil. But we know that it requires fully 5-i- times as much heat to convert the boiling nr* ft water into steam. Therefore, = 6f , is o.o the weight of water that would be converted into steam by one pound of coal. Mr. Watt found, that it requires 8 feet sur- face of boiler to be exposed to fire to boil off one cubic foot of water per hour, and that a bushel or 84 pounds of Newcastle coal so applied, will boil off from 8 to 12 cubic feet. He rated the heat expended in boiling off a cubic foot of water, to be about six times as much as would bring it to a boiling heat from the medium temperature (55) in this climate. The mean quantity is 10 cubic feet, which weigh 625 pounds. Hence, I pound of coal burnt, is equivalent to boil off in steam nearly 7 Ibs. of water, at the temperature of 55. In situations where wood was employed for fuel to Mr. Watt's engines, he allowed three times the weight of it, that he did of New- castle coal. The cubical coal of the Glasgow coal district is reckoned to have only f the calorific power of the Newcastle coal ; and the small coal or culm requires to be used in double weight, to produce an equal heat with the larger pieces. A bushel of Newcastle coal is equivalent to a hundred weight of the Glasgow. I shall now describe the experiments recently made on this subject by Sir II. Davy, subser- vient to his researches on the nature of flame. A mercurial gas-holder, furnished with a system of stop-cocks, terminated in a strong tube of platinum, having a minute aperture. Above this was fixed a copper cup tilled with olive oil, in which a thermometer was placed. The oil was heated to 212, to prevent any differ- ence in the communication of heat, by the condensation of aqueous vapour; the pressure was the same for the different gases ; and they were consumed as nearly as possible in the same time, and the flame applied to the same point of the copper cup, the bottom of which was wiped after each experiment. The results were as follows : Rise of therm. Oxygen Ratios of from 2120 to consumed, heat. Substances. Olefiant gas, 270 Hydrogen, 238 Sulph. hydrogen, 232 Coal gas, 236 Carbonic oxide, 218 6.0 9.66 1.0 26.0 3.0 6.66 4.0 6.00 1.0 6.00 The data on which Sir H. calculates the ratios of heat are the elevations of temperature and the quantities of oxygen consumed con- jointly. We see that hydrogen produces more heat in combustion than any of its compounds, a fact accordant with Mr. Dalton's results in the former table ; only Sir H. Davy's ratio is more than double that of Mr. Dalton's, as to hydrogen, and carburetted hydrogen. On this point, however, Sir H. with his usual sagacity remarks, that it will be useless to reason upon the ratios as exact, for charcoal was deposited from both the olefiant gas and coal gas during the experiment, and much sulphur was depo- sited from the sulphuretted hydrogen. It con- firms, however, the general conclusions, and proves that hydrogen stands at the head of the scale, and carbonic oxide at the bottom. It might at first view be imagined, that, according to this scale, the flame of carbonic oxide ought to be extinguished by rarefaction at the same degree as that of carburetted hydrogen ; but it must be remembered, as has been already shown, that carbonic oxide is much more easily kindled, a more accendible gas. 4. Of the causes which modify or extinguish combustion or flame. The earlier experimenters upon the Boy lean vacuum observed, that flame ceased in highly rarefied air ; but the degree of rarefaction ne- cessary for this effect has been differently stated. On this point Sir H. Davy's investi- gations are peculiarly beautiful and instructive. When hydrogen gas, slowly produced from a proper mixture, was inflamed at a fine orifice of a glass tube, as in Priestley's philosophical candle, so as to make a jet of flame of about 1 -6th of an inch in height, and introduced under the receiver of an air-pump, containing from 200 to 300 cubical inches of air, the flame enlarged COM S54 COM as the receiver became exhausted ; and when the gauge indicated a pressure between 4 and 5 times less than that of the atmosphere, was at its maximum of size; it then gradually diminished below, but burned above, till its pressure was between 7 and 8 times less; when it became extinguished. To ascertain whether the effect depended upon the deficiency of oxygen, he used a larger jet with the same apparatus, when the flame, to his surprise, burned longer ; even when the atmosphere was rarefied 1 times ; and this in repeated trials. When the larger jet was used, the point of the glass tube became white-hot, and continued red-hot till the flame was extin- guished. It immediately occurred to him, that the heat communicated to the gas by this tube was the cause that the combustion continued longer in the last trials when the larger flame was used ; and the following experiments con- firmed the conclusion. A piece of wire of platinum was coiled round the top of the tube, so as to reach into and above the flame. The jet of gas of l-6th of an inch in height was lighted, and the exhaustion made. The wire of platinum soon became white-hot in the centre of the flame, and a small point of wire near the top fused. It continued white-hot till the pressure was 6 times less. When it was 10 times, it continued red-hot at the upper part, and as long as it was dull red, the gas, though cer- tainly extinguished below, continued to burn in contact with the hot wire ; and the com- bustion did not cease until the pressure was reduced 13 times. It appears from this result, that the flame of hydrogen is extinguished in rarefied atmo- spheres, only when the heat it produces is in- sufficient to keep up the combustion ; which appears to be when it is incapable of commu- nicating visible ignition to metal ; and as this is the temperature required for the inflamma- tion of hydrogen (see section 1st), at common pressure, it appears that its combustibility is neither diminished nor increased by rarefaction from the removal of pressure. According to this view with respect to hy- drogen, it should follow, that those amongst other combustible bodies, which require less heat for their accension, ought to burn in more rarefied ah- than those that require more heat ; and those which produce much heat in their combustion ought to burn, other circumstances being the same, in more rarefied air, than those that produce little heat. Every experiment since made confirms these conclusions. Thus olefiant gas, which approaches nearly to hydro- gen, in the temperature produced by its com- bustion, and which does not require a much higher temperature for its accension, when its flame was made by a jet of gas from a bladder connected with a small tube, furnished with a wire of platinum, under the same circum- stances as hydrogen, ceased to burn when the pressure was diminished between 10 and 11 times. And the flames of alcohol and of the wax taper, which require a greater consumption of caloric for the volatilization and decompo- sition of their combustible matter, were extin- guished when the pressure was 5 or 6 times less without the wire of platinum, and 7 or 8 times less when the wire was kept in the flame. Light carburetted hydrogen, which produces, as we have seen, less heat in combustion than any of the common combustible gases, except carbonic oxide, and which requires a higher temperature for its accension than any other, has its flame extinguished, even though the tube was furnished with the wire when the pressure was below l-4th. The flame of carbonic oxide, which, though it produces little heat in combustion, is as accendible as hydrogen, burned when the wire was used, the pressure being l-6th. The flame of sulphuretted hydrogen, the heat of which is in some measure carried off by the sulphur produced by its decomposition during its combustion in rare air, when burned in the same apparatus as the olefiant and other gases, was extinguished when the pressure was ]-7th. Sulphur, which requires a lower temperature for its accension than any common inflamma- ble substance, except phosphorus, burned with a very feeble blue flame in air rarefied 15 times ; and at this pressure the flame heated a wire of platinum to dull redness ; nor was it extinguished till the pressure was reduced to l-20th. From the preceding experimental facts we may infer, that the taper would be extinguished at a height of between 9 and 10 miles, hydrogen between 12 and 13, and sul- phur between 15 and 16. Phosphorus, as has been shown by M. Van Marum, burns hi an atmosphere rarefied 60 times. Sir H. Davy found, that phosphuretted hydrogen produced a flash of light when ad- mitted into the best vacuum that could be made by an excellent pump of Nairne's con- struction. Chlorine and hydrogen inflame at a much lower temperature than oxygen and hydrogen. Hence, the former mixture explodes when rare- fied 24 times: the latter ceases to explode when rarefied 18 times. Heat extrinsically applied carries on combustion when it would otherwise be extinguished. Camphor, in a thick metallic tube, which disperses the heat, ceases to burn in air rarefied 6 times ; in a glass tube which becomes ignited, the flame of camphor exists under a ninefold rarefaction. Contact with a red-hot iron makes naphtha glow with a lambent flame at a rarefaction of 30 times; though without foreign heat, its flame dies at an atmospheric rarefaction of 6. If the mixture of oxygen and hydrogen, ex- panded to its non-explosive tenuity, be exposed to the ignition of a glass tube, the electric spark will then cause an explosion, at least in the heated portion of the gases. COM 355 COM We shall now detail briefly the effects of rarefaction by heat on combustion and explo- sion. Under CALORIC we have shown, that air, by being heated from 32 to 212 expands 3-8ths, or 8 parts become 11. Sir H. Davy justly estimates the temperature corresponding to an increase of one volume of air at 212, into 2 volumes (which took place when the enclosing glass tube began to soften with igni- tion), at 1035 Fahr. Sir H. introduced into a small glass tube, over well boiled mercury, a mixture of two parts of hydrogen and one of oxygen, and heated the tube by a spirit-lamp, till the vo- lume of the gas was increased from 1 to 2.5. By means of a blowpipe and another lamp, he made the upper part of the tube red-hot, when an explosion instantly took place. This ex- periment refutes the notions of M. de Grott- hus, on the non-explosiveness of that mixture, when expanded by heat. He introduced into a bladder a mixture of oxygen and hydrogen, and connected this bladder with a thick glass tube of about one-sixth of an inch in diameter, and three feet long, curved so that it could be gradually heated in a charcoal furnace : two spirit-lamps were placed under the tube, where it entered the charcoal fire, and the mixture was very slowly pa&sed through. An explo- sion took place before the tube was red-hot. This fine experient shows, that expansion by heat, instead of diminishing the accendibility of gases, enables them, on the contrary, to ex- plode apparently at a lower temperature; which seems perfectly reasonable, as a part of the heat communicated by any ignited body must be lost in gradually raising the tempe- rature. M. de Grotthus has stated, that if a glowing coal be brought into contact with a mixture of oxygen and hydrogen, it only rarefies them, but does not explode them . This depends on the degree of heat communicated by the coal. If it is red in day-light, and free from ashes, it uniformly explodes the mixture. If its red- ness be barely visible in the shade, it will not explode them, but cause their slow combina- tion. The general phenomenon is wholly un- connected with rarefaction, as is shown by the following circumstance : When the heat is greatest, and before the invisible combination is completed, if an iron wire, heated to white- ness, be placed upon the coal within the ves- sel, the mixture instantly explodes. Subcarburetted hydrogen, or fire-damp, as has been shown, requires a very strong heat for its inflammation. It therefore offered a good substance for an experiment on the effect of high degrees of rarefaction, by heat, on combustion. One part of this gas, and eight of air, were mixed together, and introduced into a bladder furnished with a capillary tube. This tube was heated till it began to melt. The mixture was then passed through it into the flame of a spirit-lamp, when it took fire, and burned with its own peculiar explosive light, beyond the flame of the lamp ; and when withdrawn, though the aperture was quite white-hot, it continued to burn vividly. That the compression in one part of an ex- plosive mixture, produced by the sudden ex- pansion of another part by heat, or the electric spark, is not the cause of combustion, as has been supposed by Mr. Higgins, M. Berthollet, and others, appears to be evident from what has been stated, and is rendered still more so by the following facts : A mixture of biphos- phuretted hydrogen gas and oxygen, which explode at a heat a little above that of boiling water, was confined by mercury, and very gra- dually heated on a sand bath. When the temperature of the mercury was 242, the mixture exploded. A similar mixture was placed in a receiver communicating with a condensing syringe, and condensed over mer- cury till it occupied only one-fifth of its ori- ginal volume. No explosion took place, and no chemical change had occurred ; for when its volume was restored, it was instantly exploded by the spirit-lamp. It would appear then that the heat given out by the compression of gases, is the real cause of the combustion which it produces ; and that at certain elevations of temperature, whether in rarefied or compressed atmospheres, explosion or combustion occurs ; that is, bo- dies combine with the production of heat and light. * Since it appears that gaseous matter ac- quires a double, triple, quadruple, &c. bulk, by the successive increments of 480 F. 2 X 480, 3 X 480, &c. we may gain ap- proximations to the temperature of flame, by measuring the expansion of a gaseous mixture at the instant of explosion, provided the re- sulting compound gas occupy, after cooling, the same bulk as the sum of its constituents. Now this is the case with chlorine and hydro- gen, and with cyanogen and oxygen. The latter detonated in the proportion of one to two in a tube of about two-fifths of an inch diameter, displaced a quantity of water, which demonstrated an expansion of 15 times then- original bulk. Hence 15 X 480 = 7200 of Fahr. ; and the real temperature is probably much higher, for heat must be lost by com- munication to the tube and the water. The heat of the gaseous carbon in combustion in this gas appears more intense than that of hydrogen ; for it was found that a filament of platinum was fused by a flame of prussine (cyanogen) in the air, which was not fused by a similar flame of hydrogen. We have thus detailed the modifications produced in combustion by rarefaction, me- chanical and calorific. It remains on this head to state the effects of the mixture of dif- ferent gases, and those of different cooling ori- fices, on flame. In Sir H. Davy's first paper on the fire- A A2 COM 356 COM damp of coal mines, he mentioned that car- bonic acid had a greater influence in destroy- ing the explosive power of mixtures of fire- damp and air, than azote ; and he supposed the cause to be its greater density and capacity for heat, in consequence of which it might exert a greater cooling agency, and thus pre- vent the temperature of the mixture from be- ing raised to that degree necessary for com- bustion. He subsequently made a series of experiments with the view of determining how far this idea is correct, and for the purpose of Prevented by Of hydrogen 8 Oxygen, 9 Nitrous oxide, 1 1 Subcarburetted hydrogen, 1 Sulphuretted hydrogen, 2 Olefiant gas, \ Muriatic acid gas, 2 Chlorine, ' Silicated fluoric gas, ~ Azote, ' : ' Carbonic acid * ' " The first column of the preceding table shows, that other causes, besides density and capacity for heat, interfere with the pheno- mena. Thus nitrous oxide, which is nearly one-third denser than oxygen, and which, ac- cording to Delaroche and Berard, has a greater capacity for heat, in die ratio of 1.3503 to 0.9765 by volume, has lower powers of pre- venting explosion. Hydrogen also, which is fifteen times lighter than oxygen, and which in equal volumes has a smaller capacity for heat, certainly has a higher power of prevent- ing explosion ; and olefiant gas exceeds all other gaseous substances, in a much higher ratio than could have been expected from its density and capacity. I have deduced the third column, from Sir H. Davy's experiments, on the relative times in which a thermometer, heated to 160, when plunged into a volume of 21 cubic inches of the respective gases at 52, took to cool down to 106. Where an elastic fluid exerts a cool- ing influence on a solid surface, the effect must depend principally upon the rapidity with which its particles change their places; but where the cooling particles are mixed through- out a mass with other gaseous particles, their effect must depend principally upon the power they possess of rapidly abstracting heat from the contiguous particles ; and this will depend probably upon two causes, the simple abstract- ing power by which they become quickly heated, and their capacity for heat, which is great in proportion as their temperatures are less raised by this abstraction. The power of elastic fluids to abstract heat from solids, ap- pears from the above experiments to be in some inverse ratio to their density ; and there seems to be something in the constitution of the light gases, which enables them to carry off heat ascertaining the general phenomena of the effects of the mixture of gaseous substances upon explosion and combustion. He took given volumes of a mixture of two parts of hydrogen and one part of oxygen by measure, and diluting them with various quantities of different elastic fluids, he ascer- tained at what degree of dilution the power of inflammation by a strong spark from a Leyden phial was destroyed. He found that for one of the mixture, inflammation was Permitted with 6 7 10 . 4 A Cooling power, air I. 2.66 1-12 0.75 (the mean) 2. 18 (coal gas) 1.6 0.66 1.33 . 0.727 from solid surfaces in a different manner from that in which they would abstract it in gaseous mixtures, depending probably on the mobility of their parts. Those particles which are lightest must be conceived most capable of changing place, and would therefore cool solid surfaces most rapidly : in the cooling of gaseous mixtures, the mobility of the particles can be of little consequence. Whatever be the cause of the different cool- ing powers of the different elastic fluids in pre- venting inflammation, very simple experiments show that they operate uniformly with respect to the different species of combustion ; and that those explosive mixtures, or inflammable bodies, which require least heat for their com- bustion, require larger quantities of the dif- ferent gases to prevent the effect, and vice versa. Thus one of chlorine and one of hy- drogen still inflame when mixed with eighteen times their bulk of oxygen ; whereas a mix- ture of carburetted hydrogen and oxygen, in the proper prqportions (one and two) for com- bination, have their inflammation prevented by less than three times their volume of oxy- gen. A wax taper was instantly extinguished in air mixed with one-tenth of silicated fluoric acid, and in air mixed with one-sixth of mu- riatic acid gas; but the flame of hydrogen burned readily in those mixtures ; and in mix- tures which extinguished the flame of hydro- gen, the flame of sulphur burned. (See the beginning of section 1st). In cases, however, in which the heat re- quired for chemical union is very small, as in the instance of hydrogen and chlorine, a mix- ture which prevents inflammation will not prevent combination ; that is, the gases will combine without any flash. If two volumes of carburetted hydrogen be added to a mix- COM 357 COM tare of one of chlorine with one of hydrogen, muriatic acid is formed throughout the mix- ture, and heat produced, as was evident from the expansion when the spark passed, and the rapid contraction afterwards ; but the heat was so rapidly carried off by the quantity of car- buretted hydrogen, that no flash was visible. Experiments on combustion in condensed air, to see if the cooling power was much increased thereby, show that, as rarefaction does not diminish considerably the heat of flame in atmospherical ah", so neither does condensation considerably increase it ; a cir- cumstance of great importance in the constitu- tion of our atmosphere, which at all heights or depths, at which man can exist, still pre- serves the same relations to combustion. It may be concluded from the general law, that, at high temperatures, gases not con- cerned in combustion will have less power of preventing that operation, and likewise that steam and vapours, which require a consider- able heat for their formation, will have less effect in preventing combustion, particularly of those bodies requiring low temperatures, than gases at the usual heat 6f the atmo- sphere. Thus a very large quantity of steam is required to prevent sulphur from burning. A mixture of oxygen and hydrogen will ex- plode by the electric spark, though diluted with five times its volume of steam ; and even a mixture of air and carburetted hydrogen gas, the least explosive of all mixtures, re- quires a third of steam to prevent its explo- sion, whereas one-fifth of azote will produce that effect. These trials were made over mercury. Heat was applied to water over the mercury, and 37.5 for 100 parts =. f, was regarded as the correction for the expansion of the gases. We shall now treat of the, effects of cooling orifices on flame. The knowledge of the cool- ing power of elastic media, in preventing the explosion of the fire-damp, led the illustrious English chemist to those practical researches which terminated in his grand discovery of the wire-gauze safe-lamp. The general in- vestigation of the relation and extent of those powers, serves to elucidate the operation of wire-gauze, and other tissues or systems of apertures permeable to light and air, in inter- cepting flame, and confirms the views origin- ally given of this marvellous phenomenon. We have seen that flame is gaseous matter, heated so highly as to be luminous, and that to a degree of temperature beyond the white heat of solid bodies ; for air not luminous will communicate this degree of heat. When an attempt is made to pass tiame through a very fine mesh of wire-gauze of the common tem- perature, the gauze cools each portion of the elastic matter that passes through it, so as to reduce its temperature below that degree at which it is luminous. This diminution of temperature is proportional to the smallness of die mesh, and to the mass of the metal. The power of a metallic or other tissue to prevent explosion, will depend upon the heat required to produce the combustion, as com- pared with that acquired by the tissue. Hence, the flame of the most inflammable substances, and of those that produce most heat in com- bustion, will /pass through a metallic tissue, that will interrupt the flame of less inflamma- ble substances, or those that produce little heat in combustion. Or, the tissue being the same, and impermeable to all flames at com- mon temperatures, the flames of the most combustible substances, and of those which produce most heat, will most readily pass through it when it is heated, and each will pass through it at a different degree of tem- perature. In short, all the circumstances which apply to the effect of cooling mixtures upon flame will apply to cooling perforated surfaces. Thus, the flame of phosphuretted hydrogen, at common temperatures, will pass through a tissue sufficiently large, not to be immediately choaked up by the phosphoric acid formed, and the phosphorus deposited. If a tissue, containing above 700 apertures to the square inch, be held over the flame of phos- phorus or phosphuretted hydrogen, it does not transmit the flame till it is sufficiently heated to enable the phosphorus to pass through it in vapour. " Phosphuretted hydrogen is decom- posed by flame, and acts exactly like phos- phorus. In like manner, a tissue of 100 apertures to the square inch, made of a wire of one-sixtieth, will, at common temperatures, intercept the flame of a spirit-lamp, but not that of hydrogen. But when strongly heated, it no longer arrests the flame of alcohol. A tissue which will not interrupt the flame of hydrogen when red-hot will still intercept that of olefiant gas ; and a heated tissue, which would communicate explosion from a mixture of olefiant gas and air will stop an explosion from a mixture of fire-damp, or carburetted hy- drogen. The latter gas requires a considerable mass of heated metal to inflame it, or contact with an extensive heated surface. An iron-wire of l-20th of an inch, and eight inches long, red- hot, when held perpendicularly in a stream of coal gas, did not inflanne it ; nor did a short wire of one-sixth of an inch produce the effect, when held horizontally. But wire of the latter size, when six inches of it were red-hot, and when it was held perpendicularly in a bottle containing an explosive mixture, so that heat was communicated successively to portions of the gas, produced its explosion. The scale of gaseous accension, given in the first section, explains why so fine a mesh of wire is required to hinder the explosion from hydrogen and oxygen to pass ; and why so coarsa a texture and wire control the explosion of fire-damp. The general doctrine, indeed, of the operation of wire-gauze, cannot be better elucidated, than in its effects upon the flame of sulphur. When wire-gauze of COO or 700 COM 358 COM apertures to the square inch, is held over the flame, fumesof condensed sulphur immediately come through it, and the flame is intercepted. The fumes continue for some instants, but on the increase of the heat, they diminish ; and at the moment when they disappear, which is long before the gauze becomes, red-hot, the flame passes ; the temperature at which sulphur burns being that at which it is gaseous. Where rapid currents of explosive mixtures, however, are made to act upon wire-gauze, it is of course much more rapidly heated ; and therefore, the same mesh which arrests the flames of explosive mixtures at rest, will suffer them to pass when in rapid motion. But, by increasing the cooling surface, by diminishing the apertures in size, or increasing their depth, all flames, however rapid their motion, may be arrested. Precisely the same law applies to explosions acting in close vessels. Very minute apertures, when they are only few in number, will permit explosions to pass, which are arrested by much larger apertures when they fill a whole surface. A small aperture was drilled at the bottom of a wire-gauze lamp, in the cylindrical ring, which confines the gauze. This, though less than 1-1 8th of an inch in diameter, transmitted the llame, and fired the external atmosphere, in consequence of the whole force of the explosion of the thin stratum of the mixture included within the cylinder driving the flame through the aperture. Had the whole ring, however, been composed of such apertures separated by wires, it would have been perfectly safe. Nothing can demonstrate more decidedly, than these simple facts and observations, that the interruption of flame, by solid tissues, permeable to light and air, depends upon x no recondite or mysterious cause, but on their cooling powers, simply considered as such. When a light, included in a cage of wire- gauze, is introduced into an explosive atmo- sphere of fire-damp at rest, the maximum of heat is soon obtained : the radiating power of the wire, and the cooling effect of the atmo- sphere, more efficient from the admixture of inflammable air, prevent it from ever arriving at a temperature equal to that of dull redness. In rapid currents of explosive mixtures of fire-damp, which heat common gauze to a higher temperature, twilled gauze, in which the radiating surface is considerably greater, and the circulation of air less, preserves an equable temperature. Indeed, the heat com- municated to the wire by combustion of the fire-damp in wire-gauze lamps, is completely in the power of the manufacturer. By diminishing the apertures, and increasing the mass of metal, or the radiating surface, it may be diminished to any extent. Thick twilled gauze, made of wires l-40th, 16 to the warp, and 30 to the weft, riveted to the screw to prevent the possibility of displacement, forms a lamp cage, which, from its flexibility, can- not be broken, and from its strength cannot be crushed, except by a very violent blow. The lamp which has been found most convenient for the miner, is that composed of a cylinder of strong wire-gauze, fastened round the flame by a screw, and in which the wick is trimmed by a wire passing through a safe aperture. Such have now been used for many years, in the most dangerous mines of England, without any accident. Whatever explosive disasters have happened since may be imputed to the neglect, or gross and culpable mis- management, of that infallible protector. See LAMP. When the fire-damp is inflamed in the wire-gauze cylinders, coal dust thrown into the lamp burns with strong flashes and scintillations. The miners were at first alarmed by an effect of this kind, produced by the dust naturally raised during the working of the coals. But Sir H. Davy showed, by decisive ex- periments, that explosion could never be communicated by them to the gas of any mine. He repeatedly threw coal-dust, powdered rosin, and witch-meal, through lamps burning in more explosive mixtures than ever occur in coal mines ; and though he kept these sub- stances floating in the explosive atmosphere, and heaped them upon the top of the lamp when it was red hot, no explosion could ever be communicated. Phosphorus or sulphur are the only substances which can produce explo- sion, by being applied to the outside of the lamp ; and sulphur, to produce the effect, must be applied in large quantities, and fanned by a current of fresh air. He has even blown repeatedly fine coal dust mixed with minute quantities of the finest dust of gun- powder, through the lamp burning in explosive mixtures, without any communication of ex- plosion. The most timorous female might traverse an explosive coal mine, guided by the light of the double cylinder lamp, without . feeling the slightest apprehension. 5. We have now arrived at the most curious of all Sir H.'s discoveries relative to fire, namely, invisible combustion. On passing mixtures of hydrogen and oxygen through tubes heated below redness, steam appeared to be formed without any combustion. This led him to expose mix- tures of oxygen and hydrogen to heat, in tubes, in which they were confined by fluid fusible metal. He found, that by carefully applying a heat between the boiling point of mercury, which is not sufficient for the effect, and a heat approaching to the greatest heat that can be given without making glass luminous in darkness, the combination was effected without any violence, and without any light ; and commencing with 212, the volume of steam formed at the point of combination appeared exactly equal to that of the original gases. So that the first effect, in experiments COM 359 COM of this kind, is an expansion, afterwards a contraction, and then the restoration of the primitive volume. When this change is going on, if the heat be quickly raised to redness, an explosion takes place. With small quantities of gas, the invisible combustion is completed in less than a minute. It is probable that the slow combination without combustion, long ago observed with respect to hydrogen and chlo- rine, oxygen and metals, will happen at certain temperatures with most substances that unite by heat On trying charcoal, he found, that at a temperature which appeared to be a little above the boiling point of quicksilver, it con- verted oxygen pretty rapidly into carbonic acid, without any luminous appearance ; and at a dull red heat, the elements of olefiant gas combined in a similar manner with oxygen, slowly and without explosion. The effect of the slow combination of oxygen and hydrogen is not connected with their rarefaction by heat, for it took place when the gases were confined in a tube by fusible metal, rendered solid at its upper surface; and certainly as rapidly, and without any appearance of light. As the temperature of flame has been shown to be infinitely higher than that neces- sary for the ignition of solid bodies, it ap- peared probable, that in these silent combi- nations of gaseous bodies, when the increase of temperature may not be sufficient to render the gaseous matters themselves luminous, yet it still might be adequate to ignite solid mat- ters exposed to them. Sir II. Davy had devised several experi- ments on this subject. He had intended to expose fine wires to oxygen and olefiant gas, and to oxygen and hydrogen, during their slow combination under different circumstances, when he was accidentally led to the knowledge of the fact, and at the same time to the discovery of a new and curious series of phe- nomena. lie was making experiments on the increase of the limits of the combustibility of gaseous mixtures of coal gas and air, by increase of temperature. For this purpose, a small wire- gauze safe-lamp, with some fine wire of plati- num fixed above the flame, was introduced into a combustible mixture, containing the maximum of coal gas. When the inflamma- tion had taken place in the wire-gauze cylinder, he threw in more coal gas, expecting that the heat acquired by the mixed gas, in passing through the wire-gauze, would prevent the excess from extinguishing the flame. The flame continued for two or three seconds after the coal gas was introduced ; and when it was extinguished, that part of the wire of platinum which had been hottest, remained ignited, and continued so for many minutes. When it was removed into a dark room, it was evident that there was no flame in the tylinder. It was immediately obvious that this was the result which he had hoped to attain by other methods, and the oxygen and coal gas in contact with the hot wire combined without flame, and yet produced heat enough to pre- serve the wire ignited, and keep up their own secret combustion. The truth of this conclusion was proved by introducing a heated wire of platinum into a similar mixture. It imme- diately became ignited nearly to whiteness, as if it had been in actual combustion itself, and continued glowing for a long while. When it was extinguished, the inflammability of the mixture was found to le entirely destroyed. A temperature much below ignition only was necessary for producing this curious pheno- menon, and the wire was repeatedly taken out and cooled in the atmosphere till it ceased to be visibly red ; yet when admitted again, it instantly became rcd-hor. The same phenomena were produced with mixtures of olefiant gas and air, carbonic oxide, prussic gas, and hydrogen ; and in this last case with a rapid production of water. The degree of heat could be regulated by the thickness of the wire. When of the same thickness, the wire became more ignited in hydrogen than in mixtures of olefiant gas, and more in mixtures of olefiant gas than in those of gaseous oxide of carbon. When the wire was very fine, as l-80th of an inch in diameter, its heat increased in very combustible mixtures, so as to explode them. The same wire in less combustible mixture continued merely bright red, or dull red, ac- cording to the nature of the mixture. In mixtures not explosive by flame within certain limits, these curious phenomena took place, whether the air or the inflammable gas was in excess. The same circumstances occurred with certain inflammable vapours. Those of ether, alcohol, oil of turpentine, naphtha, and camphor, have been tried. There cannot be a better mode of illustrating the fact, than by an experiment on the vapour of ether or of alcohol, which any person may make in a minute. Let a drop of ether be thrown into a cold glass, or a drop of alcohol into a warm one ; let a few coils of wire of platinum, of the l-60th or l-70th of an inch, be heated at a hot poker or a candle, and let it be brought into the glass : In some part of the glass it will become glowing, almost white-hot, and will continue so, as long as a sufficient quantity of vapour and of air remain in the glass. When the experiment on the slow com- bustion of ether is made in the dark, a pale phosphorescent light is perceived above the wire, which is of course most distinct when the wire ceases to be ignited. This appearance is connected with the formation of a peculiar acrid volatile substance, possessed of acid pro- perties. See ACID (l/AMPicj. The above experiment has been ingeniously varied bf COM COM sticking loosely on the wick of a spirit-lamp a coil of fine platinum wire, about -yi^ of an inch in thickness. There should be about 1 spiral turns, one-half of which should surround the wick, and the other rise above it. Having lighted the lamp for an instant, on blowing it out, the wire will become brightly ignited, and will continue to glow as long as any alcohol remains. A cylinder of camphor may be sub- stituted for both wick and spirit. The ignition is very bright, and exhales an odoriferous vapour. With oil of turpentine, the lamp burns invisibly without igniting the wire ; for a dense column of vapour is perceived to ascend from the wire, diffusing a smell by many thought agreeable. By adding essential oils in small, quantities to the alcohol, various aromas may be made to perfume the air of an apartment. But the film of charcoal which in this case collects on the platina coil must be removed by ignition over another spirit flame, otherwise the effect ceases after a cer- tain time. The chemical changes in general produced by slow combustion appear worthy of investi- gation. A wire of platinum introduced under the usual circumstances into a mixture of prussic gas (cyanogen) and oxygen in excess, became ignited to whiteness, and the yellow vapours of nitrous acid were observed in the mixture. In a mixture of olefiant gas, non- explosive from the excess of inflammable gas, much carbonic oxide was formed. Platinum and palladium, metals of low conducting powers, and small capacities for heat, alone succeed in producing the above phenomena. A film of carbon or sulphur deprives even these metals of this property. Thin laminae ,of the metals, if their form admits of a free circulation of air, answer as wtll as fine wires ; and a large surface of platinum may be made red-hot in the vapour of ether, or in a com- bustible mixture of coal gas and air. Sir H. Davy made an admirable practical application of these new facts. By hanging some .coils of tine platinum wire, or a fine sheet of platinum or palladium, above the wick of the safe-lamp in the wire-gauze cylinder, he has supplied the coal-miner with light in mixtures of fire-damp no longer explosive. Should the flame be extinguished by the quantity of fire-damp, the glow of the plati- num will continue to guide him ; and by placing the lamp in different parts of the gal- lery, the relative brightness of the wire will show the state of the atmosphere in these parts. Nor can there be any danger with respect to respiration wherever the wire continues ignited ; for even this phenomenon ceases, when the foul air forms about of the volume of the atmosphere. Into a wire-gauze safe>lamp, a small cage made of fine wire of platinum, of l-70th of an inch in thickness, was introduced, and fixed by means of a thick wire of platinum, about 2 inches above the lighted wick. This apparatus was placed in a large receiver, in which, by means of a gas-holder, the air could be con- taminated to any extent with coal gas. As soon as there was a slight admixture of coal gas, the platinum became ignited. The ignition continued to increase till the flame of the wick was extinguished, and till the whole cylinder became filled with flame. It then diminished. When the quantity of coal gas was increased so as to extinguish the flame, the cage of pla- tinum, at the moment of the extinction, be- came white-hot, presenting a most brilliant light. By increasing the quantity of the coal gas still further, the ignition of the platinum became less vivid. When its light was barely sensible, small quantities^ air were admitted, and it speedily increased. By regulating the admission of coal gas and air, it again became white-hot, and soon after lighted the flame in the cylinder, which as usual, by the addition of more atmospheric air, rekindled the flame of the wick. This beautiful experiment has been very often repeated, and always with the same results. When the wire for the support of the cage, whether of platinum, silver, or copper, was very thick, it retained sufficient heat to enable the fine platinum wire to rekindle in a proper mixture, half a minute after its light had been entirely destroyed by an atmosphere of pure coal gas. The phenomenon of the ignition of the platinum takes place feebly in a mixture consisting of two of air and one of coal gas; and brilliantly in a mixture con- sisting of three of air and one of coal gas. The gieater the quantity of heat produced, the greater may be the quantity of the coal gas, so that a large tissue of wire made white-hot will burn in a more inflammable mixture (that is, containing more inflammable gas) than one made red-hot. If a mixture of three parts of air and one of fire-damp be introduced into a bottle, and inflamed at its point of contact with the atmosphere, it will not explode, but will burn like a pure inflammable substance. If a fine wire of platinum, coiled at its end, be slowly passed through the flame, it will continue ignited in the body of the mixture, and the same gaseous matter will be found to be inflammable, and to be a supporter of combustion. When a large cage of wire of platinum is introduced into a very small safe- lamp, even explosive mixtures of fire-damp are burned without flame ; and by placing any cage of platinum in the bottom of the lamp round the wick, the wire is prevented from being smoked. Care should be taken, of course, that no filament of the platinum pro- trude through the wire-gauze. It is truly wonderful, that a slender tissue of platinum, which does not cost one shilling, and which is, imperishable, should afford in the dark and dangerous recesses of a coal mine, a most bril- liant light, perfectly safe, in atmospheres in COM 361 COM which the flame of the safety-lamp is ex- tinguished ; and which glows in every mixture of carburetted hydrogen gas that is respirable. When the atmosphere becomes again explosive, the flame is relighted. It is no less surprising, that thus also we can burn any inflammable vapour, either with or without flame, at pleasure, and make a slender wire consume it, either with a white or red heat. 6. We shall conclude the subject of com- bustion with some practical inferences. The facts detailed on insensible combustion, explain why so much more heat is obtained from fuel when it is burned quickly, than slowly ; and they show that in ail cases the temperature of the acting bodies should be kept as high as possible, not only because the general increment of heat is greater, but like- wise because those combinations are prevented, which, at lower temperatures, take place with- out any considerable production of heat. Thus in the argand lamp, and in the best fire-places, the increase of effect does not depend merely upon the rapid current of air, but likewise upon the heat preserved by the arrangement of the materials of the chimney, and com- municated to the matters entering into inflam- mation. These facts likewise explain the source of the great error into which Mr. Dalton has fallen, in estimating the heat given out in the combustion of charcoal ; and they indicate methods by which temperature may be in- creased, and the limits to certain methods. Currents of flame can never raise the heat of bodies exposed to them higher than a certain degree, that is, their own temperature. But by compression, there can be no doubt, that the heat of flames from pure supporters and combustible matter may be greatly increased, probably in the ratio of their compression. In the blowpipe of oxygen and hydrogen, the maximum of temperature is close to the aper- ture from which the gases are disengaged, that is, where their density is greatest. Probably a degree of temperature far beyond any that has yet been attained may be produced by throwing the flame from compressed oxygen and hydrogen into the voltaic arc, and thus combining the two most powerful agents for increasing temperature. The nature of the light, and form, of flames, can now be clearly understood. When in flames pure gaseous matter is burnt, the light is extremely feeble. The density of a common flame is proportional to the quantity of solid charcoal first deposited, and afterwards burned. The form of the flame is conical, because the greatest heat is in the centre of the explosive mixture. In looking steadfastly at flame, the part where the combustible matter is volatilized is seen, and it appears dark, contrasted with the part in which it begins to burn ; that is, where it is so mixed with air as to become ex- plosive. The heat diminishes towards the top of the flame, because in this part the quantity of oxygen is least. When the wick increases to a considerable size, from collecting charcoal, it cools the flame by radiation, and prevents a proper quantity of ah* from mixing with its central part; in consequence, the charcoal thrown off from the top of the flame is only red-hot, and the greater part of it escapes unconsumed. The intensity of the light of flanges in the atmosphere is increased by condensation, and diminished by rarefaction, apparently in a higher ratio than their heat : more particles capable of emitting light exist in the denser atmospheres, and yet most of these particles, in becoming capable of emitting light, absorb heat, which could not be the case in the con- densation of a pure supporting medium. The facts on rarefaction of inflammable gases show, that the luminous appearances of shooting stars and meteors cannot be owing to any inflammation of elastic fluids, but must depend on the ignition of solid bodies. Dr. H alley calculated the height of a meteor at ninety miles, and the great American meteor, which threw down showers of stones, was es- timated at seventeen miles high. The velocity of motion of these bodies must in all cases be immensely great, and the heat produced by the compression of the most rarefied air, from the velocity of motion, must be probably sufficient to ignite the mass. All the phenomena may be explained, if falling stars be supposed to be small solid bodies moving round the earth in very eccentric orbits, which become ignited only when they pass with immense velocity through the upper regions of the atmosphere ; and if the meteoric bodies which throw down stones with explosions, be supposed to be similar bodies which contain either combustible or elastic matter. When the common electrical or voltaic elec- trical spark is taken in rare air, the light is considerably diminished, as well as the heat. Yet in a receiver that contained air (JO times rarer than that of the atmosphere, a piece of wire of platinum, placed by Sir H. Davy in the centre of the luminous arc produced by the great voltaic apparatus of the Royal Institu- tion, became white-hot ; and that this was not owing to the electrical conducting powers of the platinum, was proved by repeating the experiment with a filament of glass, which instantly fused in the same position. It is evident from this, that electrical heat and light may appear in atmospheres, in which the flame of combustible bodies could not exist ; and the fact is interesting from its possible application in explaining the phenomena of the Aurora Bor calls and Australis. Finally, we may establish it as an axiom, that combustion is not the great phenomenon of chemical nature , but an adventitious ac- cidental accessory to chemical combination, or CON 362 CON decomposition ; that is, to the internal motions of the particles of bodies, tending to arrange them in a new chemical constitution. Several cases of death, from spontaneous combustion of the body, are on record. The appearances resemble those which would be produced by phosphuretted hydrogen. COMPTONITE. A new mineral found in drusy cavities, in ejected masses, on Mount Vesuvius. It occurs crystallized, in oblique four-sided prisms, which are usually truncated on their lateral edges, so as to form eight- sided prisms, terminated with flat summits. The angles of the oblique prism are probably 90 51' and 88 9'. Transparent, or semi- transparent. Gelatinizes with acids. It is sometimes accompanied with acicular Arra- gonite. It was first brought to this country by Lord Compton, in 1818. CONCRETIONS (MORBID). Solid deposites, formed by disease in the soft parts, or in the cavities of animal bodies. The former are usually called ossifications, as they seem to consist of calcareous phosphate. They are named, according to the part in which they are deposited, pineal, salivary, pulmonary, pancreatic, hepatic, prostatic, gouty. Depo- sites in cavities are generally styled calculi, from their resemblance to pebbles. These are intestinal, gall-stones or biliary, renal, and urinary. See the respective articles. CONGELATION. In addition to the methods pointed out under CALORIC, for effecting artificial congelation, we shall here describe the elegant mode by the air-pump, recently introduced by Professor Leslie. The very ingenious Dr. Cullen seems to have been the first who applied the vacuum of an air-pump to quicken the evaporation of liquids, with a view to the abstraction of heat, or artificial congelation. In the year 1755, he plunged a full phial of ether into a tumbler of water, and on placing it under the receiver, and exhausting the air, the ether boiled, and the surrounding water froze. In the year 1777, Mr. Edward Nairne, a very eminent London optician, published in the Transactions of the Royal Society, " an account of souie experiments made with an air-pump." After stating, that at a certain point of rarefaction the moisture about the pump furnished an atmosphere of vapour, which affected his comparative results with the mercurial gauge and pear gauge, he says, " I now put some sulphuric acid into the receiver, as a means of trying to make the remaining contents of the receiver, when exhausted as much as possible, to consist of permanent air only, unadulterated "with va. pour." He was thus enabled by this artificial dryncss to exhibit certain electrical phenomena to great advantage. The next step which Mr. Nairne took, was to produce artificial cold by the air-pump. " Having lately received from my friend Dr. Lind," he says, " some ether prepared by the ingenious Mr. Woolfe, I was very desirous to try whether I could produce any considerable degree of cold by the evapo- ration of ether under a receiver whilst ex- hausting." Accordingly he succeeded in sinking a thermometer, whose bulb was from time to time dipped into the ether in vacua, ] 03 below 56, the temperature of the apart- ment. Mr. Nairne made no attempt to condense the vapour in vacua by chemical means, and thus to favour its renewed forma- tion from the liquid surface ; which I consider to bo the essence of Professor Leslie's capital improvement on Cullen 's plan of artificial refrigeration. After Nairne's removing the vapour of water by sulphuric acid to produce artificial dryness, there was indeed but a slight step to the production of artificial roZrf, by the very same arrangement ; but still this step does not appear to have been attempted by any person from the year 1777 to 1810, when Professor Leslie was naturally led to make it, by the train of his researches on evaporation and hygrometry. The extreme rapidity of evaporation in vacua may be inferred from Dr. Robison's position, that all liquids boil in it, at a tem- perature 120 to 125 lower than their usual boiling point in the atmosphere. Could we find a liquid or solid substance which would rapidly imbibe alcohol, ether, or sulphuret of carbon, we would probably be able to effect reductions of temperature prodigiously greater than any hitherto reached. Water, however, has no doubt one advantage, in the superior latent heat of its vapour, which must com- pensate in a considerable degree for its inferior rapidity of vaporization. In the month of June 1810, Professor Leslie having introduced a surface of sulphuric acid under the receiver of an air-pump, and also a watch-glass filled with water, he found, that after a few strokes of the pump, the water was converted into a solid cake of ice, which being left in the rarefied medium, continued to evaporate, and after the interval of about an hour totally disappeared. When the air has been rarefied 250 times, the utmost that under such circumstances can perhaps be effected, the surface of evaporation is cooled down 120 Fahrenheit in winter, and would probably, from more copious evaporation and conden- sation, sink near 200 in summer. If the air be rarefied only 50 times, a depression of 80, or even 100, will be produced. We are thus enabled by this elegant com- bination, to freeze a mass of water in the hottest weather, and to keep it frozen, till it gradually wastes away, by a continued but invisible process of evaporation. The only thing required is, that the surface of the acid should approach tolerably near to that of the water, and should have a greater extent ; for otherwise the moisture would exhale more copiously than it could be transferred ami CON 363 CON absorbed, and consequently the dryness of the rarefied medium would become reduced, and its evaporating energy essentially impaired. The acid should be poured to the depth of perhaps half an inch, in a broad flat dish, which is covered by a receiver of a form nearly hemispherical ; the water exposed to congela- tion may be contained in a shallow cup, about half the width of the dish, and having its rim supported by a narrow porcelain ring, upheld above the surface of the acid by three slender feet. It is of consequence that the water should be insulated as much as possible, or should present only a humid surface to the contact of the surrounding medium ; for the dry sides of the cup might receive, by radiation from the external air, such accessions of heat, as greatly to diminish, if not to counteract, the refrigerating effects of evaporation. This in- convenience is in a great measure obviated, by investing the cup with an outer case, at the interval of about half an inch. If both the cup and its case consist of glass, the process of congelation is viewed most completely ; yet when they are formed of a bright metal, the effect appears, on the whole, more striking. But the preferable mode, and that which pre- vents any waste of the powers of refrigeration, is to expose the water in a saucer of porous earthen ware. At the instant of congelation, a beautiful network of icy spiculae pervades the liquid mass. The disposition of the water to fill the re- ceiver with vapour, will seldom permit even a good air-pump to produce greater rarefaction than that indicated by 3-10ths of an inch of mercury, beneath the barometrical height, at the time. But every practical object may be obtained by more moderate rarefactions, and a considerable surface of acid. The process goes on more slowly, but the ice is very solid, especially if the water have been previously purged of its air by distillation, or boiling for a considerable time. If we use a receiver, with a sliding wire passing down from its top through a collar of leathers, and attach to it a disc of glass ; on applying this to the surface of the water cup, we may instantly suspend the process of congelation ; and raising the disc as suddenly, permit the advancement of the process. In exhibiting the different modifications of this system of congelation to my pupils, J have been accustomed for many years to re- commend the employment of a series of cast- iron plates, attachable by screws and stopcocks to the air-pump. Each iron disc has a re- ceiver adapted to it. Thus we may, with one air-pump, successively put any number of freezing processes hi action. A cast-iron drum of considerable dimensions being filled with steam, by heating a small quantity of water in it, will sufficiently expel the air for producing the requisite vacuum. When it is cooled by affusion of water, one of the above transferor plates being attached to the stop-cock on its upper surface, would easily enable us, without any air-pump, to effect congelation by means of sulphuric acid, in the attenuated atmosphere. Suppose the capacity of the receiver to be l-60th of the iron cylinder; an aeriform rare- faction to this degree would be effected in a moment by a turn of the stop-cock ; and on its being returned, the moisture below would be cut off, and the acid would speedily condense the small quantity of vapour which had ascended. This cheap and powerful plan was publicly recommended by me upwards of 16 years ago, when I had a glass model of it made for class illustration. The combined powers of rarefaction, vapo- rization, and absorption, are capable of effecting the congelation of quicksilver. If this metal, contained in a hollow pear-shaped piece of ice, be suspended by cross threads near a broad surface of sulphuric acid, under a receiver ; on urging the rarefaction, it will become frozen, and may be kept in the solid state for several hours. Or otherwise, having introduced mer- cury into the large bulb of a thermometer, and attached the stem to the sliding rod of the receiver, place this over the sulphuric acid and water cup on the air pump plate. After the air has been rarefied about 50 times, let the bulb be dipped repeatedly into the very cold but unfrozen water, and again drawn up about an inch. In this way it will become incrusted with successive coats of ice, to the twentieth of an inch thick. The cup of water being now withdrawn from the receiver, the pendent icicle cut away from the bulb, and the surface of the ice smoothed with a warm finger, the receiver is again to be replaced, and the bulb being let down within half an inch of the acid, the exhaustion must be pushed to the utmost. When the syphon-gauge arrives at the tenth of an inch, the icy crust opens with fissures, and the mercury having gradually descended in the tube, till it reach its point of congelation, or 39 below zero, sinks by a sudden contraction almost into the cavity of the bulb. The apparatus being now removed, and the ball speedily broken, the metal appears a solid shining mass, that will bear the stroke of a hammer. A still greater degree of cold may be produced, by applying the same process to cool the atmosphere which surrounds the receiver. When the acid has acquired one-tenth of water, its refrigerating power is diminished only one-hundredth. When the quantity of moisture is equal to one-fourth of the concen- trated acid, the power of generating cold is reduced by a twentieth ; and when the dilution is one-half, the cooling powers become one- half or probably less. Sulphuric acid is hence capable of effecting the congelation of more than twenty times its weight of water, before it has imbibed nearly its own bulk of that CON 364 COP liquid, or has lost about one-eighth of its refrigerating power. The acid should then be removed, and reconcentrated by heat. The danger of using a corrosive acid in unskilful hands may be obviated by using oatmeal, desiccated nearly to brownness before a kitchen-fire, and allowed to cool in close vessels. With a body of this, a foot in dia- meter, and an inch deep, Professor Leslie froze a pound and a quarter of water, con- tained in a hemispherical porous cup. M uriate of lime in ignited porous pieces may also be employed as an absorbent. Even mouldering trap or whinstone has been used for experi- mental illustration with success. By the joint operation of radiation and evaporation from the surface of water, the natives of India are enabled to procure a supply of ice., when the temperature of the air is many degrees above the freezing point. Not far from Calcutta, in large open plains, three or four excavations are made in the ground, about 30 feet square, and 2 feet deep, the bottom of which is covered to the thickness of nearly a foot with sugar canes, or dried stalks of Indian corn. On this bed are placed rows of small unglazed earthen pans, about an inch and a quarter deep, and somewhat porous. In the dusk of the evening, during the months of December, January, and February, they are filled with soft water, previously boiled and suffered to cool. When the weather is very fine and clear, a great part of the water be- comes frozen during the night. The pans are regularly visited at sunrise, and their contents emptied into baskets which retain the ice. These are now carried to a conservatory made by sinking a pit 14 or 15 feet deep, lined with straw under a layer of coarse blanketing. The small sheets of ice are thrown down into the cavity, and rammed into a solid mass. The mouth of the pit is then closed up with straw and blankets, and sheltered by a thatched roof. For some additional facts on this interesting subject, see the sequel of the article DEW. CONGLOMERITE. A compound mi- neral mass in which angular fragments of rocks are imbedded. The Italian term breccia has the same meaning. In pudding-stone, the imbedded fragments are round, "bearing the marks of having been polished by attrition. CONITE. An ash or greenish-grey co- loured mineral, which becomes brown on ex- posure to the air. It is massive or stalactitic, is dull internally, and has a small-grained uneven fracture. It is brittle: sp. gr. 2.85. It dissolves in nitric acid, with slight effer- vescence, and blackens without fusing before the blowpipe. Its constituents are GJ.o car- bonate of magnesia, 28 carbonate of lime, 3.5 oxide of iron, and 1 water It is found in the Meissner trap hill in Ilessia, in Saxony, and Iceland. Dr. Macculloch has given the name Conite to a pulverulent mineral, as fusible as glass into a transparent bead, which he found in Mull and Glenfarg, in the trap hills of Kilpatrick, and the Isle of Sky. COPAL, improperly called gum copal, is a hard, shining, transparent, citron-coloured, odoriferous, concrete juice of an American tree ; but which has neither the solubility in water common to gums, nor the solubility in alcohol common to resins, at least in any con- siderable degree. By these properties it re- sembles amber. It may be dissolved by di- gestion in linseed oil, rendered drying by quicklime, with a heat very little less than sufficient to boil or decompose the oil. This solution, diluted with oil of turpentine, forms a beautiful transparent varnish, which, when properly applied, and slowly dried, is very hard and very durable. This varnish is ap- plied to snuff-boxes, tea-boards, and other utensils. It preserves and gives lustre to paintings, and greatly restores the decayed colours of old pictures, by filling up the cracks, and rendering the surfaces capable of reflecting light more uniformly. Mr. Sheldrake has found, that camphor has a powerful action on copal ; for if powdered copal be triturated with a little camphor, it softens, and becomes a coherent mass; and camphor added either to alcohol or oil of tur- pentine renders it a solvent of copal. Half an ounce of camphor is sufficient for a quart of oil of turpentine, which should be of the best quality ; and the copal, about the quan- tity of a large walnut, should be broken into very small pieces, but not reduced to a fine powder. The mixture should be set on a fire so brisk as to make the mixture boil al- most immediately; and the \essel Mr. S. re- commends to be of tin or other metalj strong, shaped like a wine-bottle with a long neck, and capable of holding two quarts. The mouth should be stopped with a cork, in which a notch is cut to prevent the vessel from bursting. It. is probably owing to the quantity of camphor it contains, that oil of lavender is a solvent of copal. Camphor and alcohol dissolve copal still more readily than camphor and oil of turpentine. Lewis had observed, that solution of am- monia enabled oil of turpentine to dissolve copal ; but it requires such nice management of the fire that it seldom succeeds completely. In the 51st volume of Tilloch's Magazine, Mr. Cornelius Varley states, that a good var- nish may be made by pouring upon the purest lumps of copal, reduced to a fine mass in a mortar, colourless spirits of turpentine, to about one-third higher than the copal, and triturating the mixture' occasionally in the course of the day. Next morning it may be poured off into a bottle for use. Successive portions of oil of turpentine may thus be worked with the same copal mass. Campho- rated oil of turpentine, and oil of spike la- vender, are also recommended as separate sol- COP 365 COP vents without trituration. The latter, however, though very good for drawings or prints, will not do for varnishing pictures, as it dissolves the paint underneath, and runs down while drying. COPPER is a metal of a peculiar reddish- brown colour ; hard, sonorous, very malleable, and ductile ; of considerable tenacity, and of a specific gravity from 8.6 to 8-9. At a de- gree of heat far below ignition, the surface of a piece of polished copper becomes covered with various ranges of prismatic colours, the red of each order being nearest the end which has been most heated ; an effect which must doubtless be attributed to oxidation, the stratum of oxide being thickest where the heat is great- est, and growing gradually thinner and thinner towards the colder part. A greater degree of heat oxidizes it more rapidly, so that it con- tracts thin powdery scales on its surface, which may be easily rubbed off; the flame of the fuel becoming at the same time of a beautiful bluish-green colour. In a heat, nearly the same as is necessary to melt gold or silver, it melts, and exhibits a bluish-green flame; by a violent heat it boils, and is volatilized partly in the metallic state. Copper rusts in the air ; but the corroded part is very thin, and preserves the metal be- neath from farther corrosion. We have two oxides of copper. The black, procurable by heat, or by drying the hydrated oxide precipitated by potash from the nitrate. It consists of 8 copper -}- 2 oxygen. It is a deutoxide. The protoxide is obtained by digesting a solution of muriate of copper with copper turnings, in a close phial. The colour passes from green to dark brown, and grey crystalline grains are deposited. The solution of these yields, by potash, a precipitate of an orange colour, which is the protoxide. It con- sists of 8 copper -f- 1 oxygen. Protoxide of copper has been lately found by Mr. Mushet, in a mass of copper, which had been exposed to heat for a considerable time, in one of the melting furnaces of the mint under his super- intendence. Copper, in filings, or thin laminse, intro- duced into chlorine, unites with flame into the chloride, of which there are two varieties ; the protochloride, a fixed yellow substance, and the deutochloride, a yellowish-brown pulveru- lent sublimate. 1. The crystalline grains de- posited from the above muriatic solution are protochloride. The protochloride is conve- niently made by heating together two parts of corrosive sublimate, and one of copper filings. An amber-coloured translucent substance, first discovered by Boyle, who called it resin of copper, is obtained. It is fusible at a heat just below redness ; and in a close vessel, or a vessel with a narrow orifice, is not decom- posed or sublimed by a strong red heat. But if air be admitted, it is dissipated in dense white fumes. It is insoluble in water.' It effervesces in nitric acid. It dissolves silently in muriatic acid, from which it may be pre- cipitated by water. By slow cooling of the fused mass Dr. John Davy obtained it crys- tallized, apparently in small plates, semi- transparent, and of a light yellow colour. It consists, by the same ingenious chemist, of Chlorine, 36 or 1 prime = 4. 5 36 Copper, 64 or 1 prime 8.0 64 100 12.5 100 2. Deutochloride is best made by slowly evaporating to dryness, at a temperature not much above 400 q Fahr. the deliquescent mu- riate of copper. It is a yellow powder. JBy absorption of moisture from the air, it passes from yellow to white, and then green, repro- ducing common muriate. Heat converts it into protochloride, with the disengagement of chlorine. Dr. Davy ascertained the chemical constitution of both these compounds, by se- parating the copper with iron, and the chlorine by nitrate of silver. The deutochloride con- sists of Chlorine, 53 2 primes 9 53 Copper, 47 1 do. 8 47 100 17 100 The iodide of copper is formed by dropping aqueous hydriodate of potash into a solution of any cupreous salt. It is an insoluble dark brown powder. Phosphtiret of copper is made by project- ing phosphorus into red-hot copper. It is of a white colour, harder than iron, pretty fusible, but not ductile. Its sp. gr. is 7- 12. It crys- tallizes in four-sided prisms. Proust, its dis- coverer, says it consists of 20 phosphorus -f- 80 copper. Phosphorus +2 X 8.0 copper, form the equivalent proportions by theory. Heat burns out the phosphorus, and scorifies the copper. Sulphur et of copper is formed by mixing together eight parts of copper filings, and two of sulphur, and exposing the mixture to a gentle heat. Whenever the sulphur is raised a little above its melting temperature, com- bustion suddenly pervades the whole mass with explosive violence. Ignition, with reciprocal saturation, con- stitutes a true combustion, of which every cha- racter is here. And since the experiment succeeds perfectly well in vacuo, or in azote, we are entitled to consider sulphur as a true supporter of combustion, if this name be re- tained is chemistry ; a name indicating what no person can prove, that one of the combining bodies is a mere supporter, and the other a mere combustible. Combustion is, on the contrary, shown by this beautiful experiment to be independent of those bodies vulgarly reckoned supporters. Indeed, sulphur bears to copper the same electrical relation that oxygen and chlorine bear to this metal. Hence sulphur is at once a supporter and a com- COP 360 COP bustible, in the fullest sense ; a fact fatal to this technical distinction, since one body cannot be possessed of opposite qualities. When a disc of copper, with an insulated handle, is made to touch a disc of sulphur, powerful electrical changes ensue ; and at a higher temperature we see, that the reciprocal attractive forces, or the corpuscular movements which accompany energetic affinity, excite the phenomena of combustion. To say that one of the combining bodies contains a latent ma- gazine of heat and light, to feed the flame of the other body, is an hypothesis altogether destitute of proof, which should therefore have no place in one of the exact sciences, far less be made the ground- work of a chemical system. Sulphuret of copper consists, according to Berzelius, of very nearly 8 copper + 2 sulphur. We may regard it as containing a prime of each constituent. Sulphuric acid, when concentrated and boiling, dissolves copper. If water be added to this, it forms a blue solution of copper, which, by evaporation, affords blue crystals, that require about four times their weight of water to dissolve them. The solutions of copper in sulphuric acid are slightly caustic. Magnesia, lime, and the fixed alkalis, precipitate the metal from them in the form of oxide. Volatile alkali precipitates all the solution of copper, but redissolves the oxide, and produces a deep blue colour. There are certain mineral waters in Hungary, Sweden, Ireland, and in various parts of England, which contain sulphate of eopper, and from which it is precipitated by the addition of pieces of old iron. Nitric acid dissolves copper with great ra- pidity, and disengages a large quantity of ni- trous gas. Part of the metal falls down in the form of an oxide ; and the filtrated or de- canted solution, which is of a much deeper blue colour than the sulphuric solution, affords crystals by slow evaporation. This salt is deliquescent, very soluble in water, but most plentifully when the fluid is heated. Its so- lution, exposed to the air in shallow vessels, :-> an oxide of a green colour. Lime precipitates the metal of a pale blue, fixed al- -kalis of a bluish -white. Volatile alkali throws down bluish flocks, which are quickly redis- solved, and produce a lively blue colour in the fluid. The saline combinations of copper were formerly called sales veneris, because Venus was the mythological name of copper. They have the following general characters : 1 . They are mostly soluble in water, and their solutions have a green or blue colour, or acquire one of these colours on exposure to air. 2. Am- monia added to the solutions, produces a deep blue colour. 3. Ferroprussiate of potash gives a reddish-brown precipitate, with cupreous salts. 4. Gallic acid gives a brown precipitate. 5. Hydrosulphuret of potash gives a black precipitate. 6. A plate of iron immersed in these solutions throws down metallic copper, and very rapidly if there be a slight excess of acid. The protoxide of copper can be com- bined with the acids only by very particular management All the ordinary salts of copper have the peroxide for a base. Acetatu of copper. The joint agency of air and acetic acid is necessary to the production of the cupreous acetates. By exposing copper plates to the vapours of vinegar, the bluish- green verdigris is formed, which by solution in vinegar constitutes acetate of copper. This salt crystallizes in four-sided truncated pyra- mids. Its colour is a fine bluish-green. Its sp. gr. is 1.78. It has an austere metallic taste ; and swallowed, proves a violent poison. Boiling water dissolves one-fifth of the salt, of which it deposits the greater part on cool- ing. It is soluble also in alcohol. It efflo- resces by exposure to air. By heat, in a retort, it yields acetic acid, and pyro-acetic spirit. Sulphuretted hydrogen throws down the cop- per from solutions of this salt, in the state of sulphuret. I had occasion to analyze this salt about two years ago, and found it to consist by experiment of Exper. Theory. Acetic acid, 52.0 2 atoms 13.26 51.98 Perox. of cop. 39.6 1 do. 10.00 39.20 Water, 8.4 1 do. 2.25 8.82 100.0 25.51 100.00 More lately, I have prepared a crystallized bin-acetate, which I found to be anhydrous. Mr. Vauquelin gives for the composition of the crystallized acetate of copper, Acetic acid . 2 atoms, 12-75 51 Oxide of copper 1 1000 40 Water 3 2.26 9 100 Verdigris is a mixture of the crystallized acetate of copper and a subacetate. A portion of the latter was extracted by washing pul- verizsd verdigris rapidly, with successive small portions of cold water, to avoid decomposi- tion. This, when dried, was analyzed, for the oxide, by ignition after nitric acid ; and for the acid by converting carbonate of potash into acetate. Its constituents were found to be nearly 63.5 oxide, and 33.5 acid. When a solution of crystallized acetate is boiled for some time it is decomposed, a little acetic acid escapes, much black oxide of copper falls down, and when the decomposition ceases, which it always ultimately does, another acetate of cop- per is found in the solution. This decompo- sition takes place in close vessels, where no acetic acid is allowed to escape. One hundred parts of the crystallized acetate deposit about 14.65 of oxide, leaving in solution 25.35 parts, combined with twice its weight of acetic acid. Hence there are three combinations of acetic acid and oxide of copper containing, the first, COP 367 COP 66.5; the second, 44.44; and the third, 33.34 of oxide. If 1 part of verdigris be mixed with oOO of distilled water, and left at a tempera- ture of 60 or 70 F. it gradually becomes yellow, then brown, and in seven or eight days no green portions are to be observed. When filtered, peroxide is obtained ; 100 parts of ver- digris were found thus to leave about 23 parts of oxide of copper. It is only the subacetate of the verdigris which undergoes this change. This subacetate is insoluble in water, but de- composable in that fluid into a peroxide and an acetate. The other two salts are the neutral acetate, resolvable by boiling in water into peroxide and superacetate ; and this superace- tate. Memoir es de Museum, x. 295. The subacetate of Proust, obtained by dis- solving verdigris in water, is said to consist of acid and water, 37 Oxide, 63. The proportion of 40 acid + 60 oxide is that of 1 atom of each, to use the hypothetical term. Now Proust's experiments seem to leave uncertainty to the amount of that differ- ence. This salt should be called probably the acetate. Proust's insoluble part of verdigris will become the subacetate. This constitutes 44 per cent., and the other 56. But the pro- portions will fluctuate; and an intermixture of carbonate may be expected occasionally. Arseniate of copper presents us with many sub-species which are found native. The arse- niate may be formed artificially by digesting arsenic acid on copper, or by adding arseniate of potash to a cupreous saline solution. 1. Obtuse octahedral arseniate, consisting of two four-sided pyramids, applied base to base, of a deep sky-blue or grass green colour. Their sp. gr. is 2.88. They consist, accord- ing to Chenevix, of 14.3 acid -f- 50 brown oxide + 35-7 water. 2. Hexahedral arseniate is found in fine six-sided laminae, divisible into thin scales. Its colour is a deep emerald- green ; and its sp. gr. 2.548. It consists, by Vauquelin, of 43 acid + 39 oxide -f- 18 water. When arseniate of ammonia is poured into nitrate of copper, this variety precipitates in small blue crystals. 3. Acute octahedral arse- niate, composed of two four-sided pyramids, applied base to base, and sometimes in rhom- boidal prisms, with dihedral summits. It consists of 29 acid -j- 50 oxide + 21 water. The last ingredient is sometimes wanting. 4. Triftedral arseniate occurs also in other forms. Colour bluish-green. It consists, by Chenevix, of 30 acid -j- 54 oxide -j- 1 6 water. 5. Superarscniate. On evaporating the super- natant solution in the second variety artificially made, and adding alcohol, M. Chenevix ob- tained a precipitate in small blue rhomboidal crystals. They were composed of 40.1 acid -f 35.5 oxide + 24.4 water. The following is a general table of the composition of these arseniates : Acid. 1. 1.00 2. 1.00 3. 1.00 4. 1.00 5. 1.00 Oxide. 3.70 2.76 1.72 1.80 0.88 Water. 2.50 1.00 0.70 0.53 0.60 Arseniate of copper, called Scheele's green, is prepared, by the old prescription of mixing a solution of 2 parts of sulphate of copper in 44 of water, with a solution of 2 parts of pot- ash of commerce, and 1 of pulverized arsenious acid, also in 44 of water. Both solutions being warm, the first is to be gradually poured into the second. The grass-green insoluble precipitate is to be well washed with water. Carbonate of copper. Of this compound there are three native varieties, the green, the blue, and the anhydrous. According to Mr. R. Philips, the following is the order of their composition : 1st. 2d. 3d. Carbonic acid, 2.75 11.00 2.75 Deutox. copper, 10.00 30.00 10.00 Water, 1.125 2.25 0.00 Weights of primes, 13.875 43.25 12.75 The artificial carbonate, obtained by Proust on adding an alkaline carbonate to a solution of the nitrate of copper, is the same with the second kind. Chlorate of copper is a deflagrating deli- quescent green salt. Fluate of copper is in small blue-coloured crystals. Hydriodate of copper is a greyish-white powder. Protomnriate of copper has already been described in treating of the chlorides. Deutomuriate of copper, formed by dis- solving the deutoxide in muriatic acid, or by heating muriatic acid on copper filings, yields by evaporation crystals of a grass-green colour,, in the form of rectangular parallelopipeds. Their sp. gr. is 1.68. They are caustic, very deliquescent, and of course very soluble in water. According to Berzelius, it consists of Acid, 40.2 Deutoxide, 59.8 100.0. The ammonia-nitrate evaporated, yields a fulminating copper. Crystals of nitrate, mixed with phosphorus, and struck with a hammer, detonate. When pulverized, then slightly moistened, and suddenly wrapt up firm in tin -foil, the nitrate produces an explosive com- bustion. The nitrate seems to consist of a prime of acid -{- a prime of deutoxide, besides water of crystallization. Subnitrate of copper is the blue precipitate, occasioned by adding a little potash to the neutral nitric solution. Nitrite of copper is formed by mixing ni- trite of lead with sulphate of copper. COP 368 COP The sulphate, or blue vitriol of commerce, is a bisulphate. Its sp. gr. is 2.2. It con- sists of Acid, 31.38 2 primes, 10.0 32.0 Oxide, 32.32 1 do. 10.0 32.0 Water, 36.30 10 do. 11.25 36.0 100-00 31.25 100.0 A mixed solution of this sulphate and sal ammoniac forms an ink, whose traces are in- visible in the cold, but become yellow when heated ; and vanish again as the paper cools. A neutral sulphate of copper may be formed by saturating the excess of acid with oxide of copper. It crystallizes in four-sided pyramids, separated by quadrangular prisms. M. Proust formed a subsulphate by adding a little pure potash to a solution of the last salt. A green- coloured precipitate falls. Protosulphite of copper is formed by pass- ing a current of sulphurous acid gas through the deutoxide of copper diffused in water. It is deprived of a part of its oxygen, and com- bines with the acid. The sulphate, simul- taneously produced, dissolves in the water; while the sulphite forms small red crystals, from which merely long ebullition iu water expels the acid. Sulphite of potash and copper is made by adding the sulphite of potash to nitrate of copper. A yellow flocculent precipitate, con- sisting of minute crystals, falls. Ammonia-sulphate of copper is the salt formed by adding water of ammonia to solu- tion of the bisulphate. It consists, according to Berzelius, of 1 prime of the cupreous, and 1 of the ammoniacal sulphate, combined to- gether; or 20.0 +7.13-1- 14.625 of water. Subsulphate of ammonia and copper is formed by adding alcohol to the solution of the preceding salt, which precipitates the sub- sulphate. It is the cuprum ammoniacum of the pharmacopoeia. According to Berzelius, it consists of Acid, 32.23 or nearly 2 primes, Deutox. of copper, 34.00 1 do. Ammonia, 26.40 4 do. Water, 7.35 2 do. 100.00 Sulphate of potash and copper is formed by digesting bisulphate of potash on the deutoxide or carbonate of copper. Its crystals are green- ish-coloured, flat parallelopipedons. It seems to consist of 2 primes of sulphate of potash + 1 prime of bisulphate of copper -f- 12 of water. The following acids, antimonic, antimo- nious, boracic, chromic, molybdic, phosphoric, tungstic, form insoluble salts with deutoxide of copper. The first two are green, the third is brown, the fourth and fifth green, and the sixth white. The benzoate is in green crystals, sparingly soluble. The oxalate is also green. The binoxalates of potash and soda, with oxide of copper, give triple salts, in green needle- form crystals. There are also ammonia-ox- alates in different varieties. Tartrate of copper forms dark bluish-green crystals. Cream-tar, trate of copper is a bluish-green powder, com- monly called Brunswick green. M. Vuaflart has observed that chromate of copper, pre- pared by precipitating sulphate of copper by chromate of potash, and which is of a reddish- brown colour, is soluble in dilute water of ammonia, producing a clear solution of a beau- tiful and deep green colour. When the solu- tion is evaporated, the reddish chromate of copper appears as the ammonia flies off. The readiest way of preparing this permanent and beautiful colour, is to add solution of chromate of potash to ammoniacal sulphate of copper. Journ. de Pkarmacie for 1824, p. 007- See SALT. To obtain pure copper for experiments, we precipitate it in the metallic state, by im- mersing a plate of iron in a solution of the deutomuriate. The pulverulent copper must be washed with dilute muriatic acid. In the wet way, Brunswick or Friezland green is prepared by pouring a saturated so- lution of muriate of ammonia over copper filings or shreds in a close vessel, keeping the mixture in a warm place, and adding more of the solution from time to time, till three parts of muriate and two of copper have been used. After standing a few weeks, the pigment is to be separated from the unoxidized copper, by washing through a sieve ; and then it is to be well washed, and dried slowly in the shade. This green is almost always adulterated with ceruse. This metal combines very readily with gold, silver, and mercury. It unites imperfectly with iron in the way of fusion. Tin combines with copper, at a temperature much lower than is necessary to fuse the copper alone. On this is grounded the method of tinning copper ves- sels. For this purpose, they are first scraped or scoured ; after which they are rubbed with sal ammoniac. They are then heated, and sprinkled with powdered resin, which defends the clean surface of the copper from acquiring the slight film of oxide that would prevent the adhesion of the tin to its surface. The melted tin is then poured in, and spread about. An extremely small quantity adheres to the cop- per, which may perhaps be supposed insuffi- cient to prevent the noxious effects of the cop- per as perfectly as might be wished. When tin is melted with copper, it com- poses the compound called bronze. In this metal the specific gravity is always greater than would be deduced by computation from the quantities and specific gravities of its com- ponent parts. The uses of this hard, sonorous, and durable composition, in the fabrication of cannon, bells, statues, and other articles, are COP 369 COP well known. Bronzes and bell-metals are not usually made of copper and tin only, but have other admixtures, consisting of lead, zinc, or arsenic, according to the motives of profit, or other inducements of the artist. But the at- tention of the philosopher is more particularly directed to the mixture of copper and tin, on account of its being the substance of which the speculums of reflecting telescopes are made. See SPECULUM. The ancients made cut- ting instruments of this alloy. A dagger ana- lyzed by Mr. Hielm consisted of 83i copper, and 16| tin. Copper unites with bismuth, and forms a reddish-white alloy. With arsenic it forms a white brittle compound, called tombac. With zinc it forms the compound called brass, and distinguished by various other names, accord- ing to the proportions of the two ingredients. It is not easy to unite these two metals in con- siderable proportions by fusion, because the zinc is burnt or volatilized at a heat inferior to that which is required to melt copper ; but they unite very well in the way of cementa- tion. In the brass works, copper is granulated by pouring it through a plate of iron, per- forated with small holes and luted with clay, into a quantity of water about four feet deep, and continually renewed : to prevent the dan- gerous explosions of this metal, it is necessary to pour but a small quantity at a time. There are various methods of combining this granu- lated copper, or other small pieces of copper, with the vapour of zinc. Calamine, which is an ore of zinc, is pounded, calcined, and mixed with the divided copper, together with a por- tion of charcoal. These being exposed to the heat of a wind furnace, the zinc becomes re- vived, rises in vapour, and combines with the copper, which it converts into brass. The heat must be continued for a greater or less num- ber of hours, according to the thickness of the pieces of copper, and other circumstances ; and at the end of the process, the heat being suddenly raised, causes the brass to melt, and occupy the lower part of the crucible. The most scientific method of making brass seems to be that mentioned by Cramer. The pow- dered calamine, being mixed with an equal quantity of charcoal and a portion of clay, is to be rammed into a melting vessel, and a quantity of copper, amounting to two-thirds of the weight of calamine, must be placed on the top, and covered with charcoal. By this management the volatile zinc ascends, and converts the copper into brass, which flows into the rammed clay ; consequently, if the calamine contain lead, or any other metal, it will not enter into brass, the zinc alone being raised by the heat. A fine kind of brass, which is supposed to be made by cementation of copper plates with calamine, is hammered out into leaves in Ger- many ; and is sold very cheap in this country, under the name of Dutch gold or Dutch metal. It is about five times as thick as gold leaf; that is to say, it is about one sixty-thousandth of an inch thick. Copper unites readily with antimony, and affords a compound of a beautiful violet co- lour. It does not readily unite with manga- nese. With tungsten it forms a dark brown spongy alloy, which is somewhat ductile. See ORES OF COPPER. Verdigris, and other preparations of copper, act as virulent poisons, when introduced in very small quantities into the stomachs of animals. A few grains are sufficient for this effect. Death is commonly preceded by very decided nervous disorders, such as convulsive movements, tetanus, general insensibility, or a palsy of the lower extremities. This event happens frequently so soon, that it could not be occasioned by inflammation or erosion of the primes vice ; and indeed, where these parts are apparently sound, it is probable that the poison is absorbed, and, through the circula- tion, acts on the brain and nerves. The cu- preous preparations are no doubt very acrid, and if death do not follow their immediate impression on the sentient system, they will certainly inflame the intestinal canal. The symptoms produced by a dangerous dose of copper are exactly similar to those which are enumerated under arsenic, only the taste of copper is strongly felt. The only chemical antidote to cupreous solutions, whose opera- tion is well understood, is water strongly im- pregnated with sulphuretted hydrogen. The alkaline hydrosulphurets are acrid, and ought not to be prescribed. But we possess, in sugar, an antidote to this poison, of undoubted efficacy, though its mode of action be obscure. M. Duval introduced into the stomach of a dog, by means of a ca- outchouc tube, a solution in acetic acid, of four French drachms of oxide of copper. Some minutes afterwards, he injected into it four ounces of strong syrup. He repeated this in- jection every half-hour, and employed alto- gether 12 ounces of syrup. The animal ex- / perienced some tremblings and convulsive movements. But the last injection was fol- lowed by a perfect calm. The animal fell asleep, and awakened free from any ailment. Orfila relates several cases of individuals who had by accident or intention swallowed poisonous doses of acetate of copper, and who. recovered by getting large doses of sugar. He uniformly found, that a dose of verdigris, which would kill a dog in the course of an hour or two, might be swallowed with im- punity, provided it was mixed with a consider- able quantity of sugar. If we boil for half an hour, in a flask, an ounce of white sugar, an ounce of vrater, and 10 grains of verdigris, we obtain a green liquid, which is not affected by the nicest tests of copper, such as ferroprussiate of potash, am- monia, and the hydrosulphurets. An inso- COT 370 CRO luble green carbonate of copper remains at the bottom of the flask. Vogel states, that sugar boiled with sulphate of copper precipitates metallic copper ; and with acetate, protoxide. COPPERAS. Sulphate of iron. CORALS seem to consist of carbonate of lime and animal matter, in equal propor- tions. CORK is the bark of a tree of the oak kind, very common in Spain and the other southern parts of Europe. By the action of the nitric acid it was found to be acidified. See ACID (SUBERIC). Cork has been recently analyzed by Che- vreul by digestion, first in water and then in alcohol. By distillation there came over an aromatic principle, and a little acetic acid. The watery extract contained a yellow and a red colouring matter, an undetermined acid, gallic acid, an astringent substance, a substance containing azote, a substance soluble in water and insoluble in alcohol, gallate of iron, lime, and traces of magnesia. 20 parts of cork treated in this way left 17-15 of insoluble matter. The undissolved residue being treated a sufficient number of times with alcohol, yielded a variety of bodies, but which seem reducible to three ; namely, cerin, resin, and an oil. The ligneous portion 6*f the cork still weighed 14 parts, which are called suiter. CORK (FOSSIL). See ASBESTOS. CORROSIVE SUBLIMATE. See MERCURY. CORUNDUM. According to Professor Jameson, this mineral genus contains 3 spe- cies, viz. octahedral corundum, rhomboidal corundum, and prismatic corundum. 1. Octohcdral is subdivided into 3 sub- species, viz. automalite, ceylanite, and spinel. 2. Rhomboidal corundum contains 4 sub- species, viz. salamstone, sapphire, emery, and corundum, or adamantine spar. 3. Prismatic, or chrysoberyl. See the se- veral sub-species, under their titles hi the Dictionary. CO TTON. This vegetable fibre is soluble in strong alkaline leys. It has a strong affi- nity for some earths, particularly alumina, several metallic oxides, and tannin. Nitric acid, aided by heat, converts cotton into oxalic acid. My analysis gives for the ultimate consti- tuents of cotton, carbon, 42.11; hydrogen, 5.06; oxygen, 52.83; or nearly Carban 11 atoms 8-25 4285 Hydrogen 8 1.00 5.30 Oxygen 10 *'.. 10-00 51.85 19.25 100.00 3000 grains of clean cotton wool, in the soft fleece, formed by the cylinder cards, being carefully burned in a silver basin, yielded on an average of 6 trials, 19 grains of light grey ashes, which is a trifle under 1 per cent. One hundred parts of the ashes of cotton seem, by my researches, to be composed of 1. Soluble matter. Carbonate of potash . 44.8 Muriate of potash 9-9 Sulphate of potash 9-3 2. Insoluble matter. Phosphate of lime * c a 9-0 Carbonate of lime .10-6 Phosphate of magnesia . 8.4 Peroxide of iron ' * h 3.0 Alumina (a trace) Loss . . 5.0 100.0 Journ. of Science, xxi. 28- COUCH. -The heap of moist barley about 16 inches deep on the malt-floor. COUZERANITE. This mineral occurs in rectangular prisms. Colour from greyish black to indigo blue. Opaque, but in their portions transparent and brilliant. Scratched by apatite. Not affected by the blowpipe. It is found in limestone, in the steep defiles of Saleix, called " des Couzerans." CREAM. The oily part of milk, which rises to the surface of that liquid, mixed with a little curd and serum. When churned, butter is obtained. Heat separates the oily part, but injures its flavour. CREAM OF TARTAR. See ACID (TARTARIC). CRIC H TONITE. This mineral occurs in very small crystals, in the form of acute rhom- boids. It is perfectly black, opaque, and of a shining lustre; cross fracture, conchoidal, and very shining. It scratches fluate of lime, but is not very hard. It occurs accompanying anatase, and on rock crystal in Dauphiny. CROCUS (SAFFRON). The yellow or saffron-coloured oxides of iron and copper were formerly called crocus martis and cro- cus veneris. That of iron is still called cro- cus simply, by the workers in metal who use it. CROCUS METALLORUM. See AN- TIMONY. CROSS-STONE. Harmotome, or pyra- midal zeolite. Its colour is greyish-white, passing into smoke-grey, sometimes massive, but usually crystallized. Primitive form, a double four-sided pyramid, of 121 58' and 86 36'. Its principal secondary forms are, a broad rectangular four-sided prism, rather acutely acuminated on the extremities with 4 planes, which are set on the lateral edges ; the preceding figure, in which the edges formed by the meeting of the acuminating planes, that rest on the broader lateral planes, are truncated ; twin crystals of the first form, in- tersecting each other, in such a manner that a common axis and acumination is formed, and the broader lateral planes make four re-enter- ing angles. The crystals are not large. The CRY 371 CRY surface of the smaller lateral planes is double- plumosely streaked. Lustre glistening, be- tween vitreous and pearly. Of the cleavage, 2 folia are oblique, and 1 parallel to the axis. Fracture perfect conchoidal. Translucent and semitransparent. Harder than fiuor spar, but not so hard as apatite. Easily frangible. Sp. gr. 2.35. It fuses with intumescence and phosphorescence, into a colourless glass. Its constituents are 49 silica, 16' alumina, 18 ba- rytes, and 15 water, by Klaproth. It has hitherto been found only in mineral veins and agate balls. It occurs at Andreasburg, in the Hartz ; at Kongsberg, in Norway ; at Ober- stein ; Strontian, in Argyllshire ; and also near Old Kilpatrick, in Scotland. Jameson. CRASSAMENTUM, orCRUOR. The clot, or coagulated part of blood. CROTON ELEUTHERIA. Cascarilla bark. The following is Trommsdorf 's ana- lysis of this substance, characterized by its emitting the smell of musk when burned. Mucilage and bitter principle 864 parts, resin 688, volatile matter 72, water 48, woody fibres 3024 ; in 4696 parts. CRUCIBLES. See LABORATORY. CRUSTS, the bony coverings of crabs, lobsters, Sec. Mr. Hatchett found them to be composed of a cartilaginous substance, like coagulated albumen, carbonate of lime, and phosphate of lime. The great excess of the second above the third ingredient distinguishes them from bones ; while the quantity of the third distinguishes them from shells. Egg- shells and snail shells belong to crusts in com-' position ; but the animal matter is in smaller quantity. By Merat-Guillot, 100 parts of lobster crust consist of 60 carbonate of lime, 14 phosphate of lime, and 26 cartilaginous matter. 100 of hen's egg-shells consist of 89.6 carbonate of lime, 5.7 phosphate of lime, 4.7 animal matter. CRYOLITE. A mineral which occurs massive, disseminated, and in thick lamellar concretions. Its colours are white and yel- lowish.brown. Lustre vitreous, inclining to pearly. Cleavage fourfold, in which the folia are parallel with an equiangular four-sided pyramid. Fracture uneven. Translucent. Harder than gypsum. Easily frangible. Sp. gr. 2-95. It becomes more translucent in water. It melts in the heat of a candle. Be- fore the blowpipe, it becomes first very liquid, and then assumes a slaggy appearance. It consists, by Klaproth, of 24 alumina, 36 soda, and 40 fluoric acid and water. It is therefore a soda-fluate of alumina. If we regard it as composed of definite proportions, we may have 1 prime alumina, 3-2 26-33 1 do. soda, 3-95 32-51 2 do. acid, 2-75 22-63 2 do. water, 2-25 18-53 41-16 12-15 100-00 Vauquelin's analysis of the same mineral gives 47 acid and water, 32 soda, and 21 alumina. This curious and rare mineral has hitherto been found only in West Greenland, at the arm of the sea named Arksut, 30 leagues from the colony of Juliana Hope. It occurs in gneiss. Mr. Allan of Edinburgh had the merit of recognizing a large quantity of this mineral, in a neglected heap brought into Leith from a captured Danish vessel. It had been collected in Greenland by that indefatiga- ble mineralogist M. Gieseke. CR YO PHORUS. The frost-bearer or car- rier of cold, an elegant instrument invented by Dr. Wollaston, to demonstrate the relation between evaporation at low temperatures, and the production of cold. If 32 grains of water, says this profound philosopher, were taken at the temperature of 62 3 . and if one grain of this were converted into vapour by absorbing 960 9 , then the whole quantity would lose 960 -zrr = 30, and thus be reduced to the tem- o' perature of 32. If from the 31 grains which still remain in the state of water, four grains more were converted into vapour by absorbing 960 9 , then the remaining 27 grains must have lost ^ of 960* = 1 42, which is rather more than sufficient to convert the whole into ice. In an experiment conducted upon a small scale, the proportional quantity evaporated did not differ much from this estimate. If it be also true that water, in assuming the gaseous state, even at a low temperature, expands to 1800 times its former bulk, then in attempting to freeze the small quantity of water above mentioned, it would be requisite to have a dry vacuum with the capacity of 5 X 1800 = 9000 grains of water. But let a glass tube be taken, having its internal diameter about of an inch, with a ball at each extremity of about one inch diameter, and let the tube be bent to a right angle at the distance of half an inch from each ball. One of these balls should be somewhat less than half full of water, and the remaining cavity should be as perfect a vacuum as can readily be obtained; which is effected by making the water boil briskly in the one ball, before sealing up the capillary opening left in the other. If the empty ball be immersed in a freezing mixture of snow and salt, the water in the other ball, though at the distance of two or three feet, will be frozen solid in the course of a very few minutes. The vapour contained in the empty ball is condensed by the common operation of cold, and the vacuum produced by this condensation gives oppor- tunity for a fresh quantity to arise from the opposite ball, with proportional reduction of its temperature. CRYSTAL. When fluid substances are suffered to pass with adequate slowness to the solid state, the attractive forces frequently ar- range their ultimate particles so as to form BB 2 CRY CRY regular polyhedral figures or geometrical solids, to which the name of crystals has been given. Most of the solids which compose the mineral crust of the earth are found in the crystallized state. Thus granite consists of crystals of quartz, felspar, and mica. Even mountain masses like clay-slate have a regular tabulated form. Perfect mobility among the corpuscles is essential to crystallization. The chemist produces it either by igneous fusion, or by solution in a liquid. When the temperature is slowly lowered in the former case, or the liquid slowly abstracted by evaporation in the latter, the attractive forces resume the ascend- ency, and arrange the particles in symmetrical forms. Mere approximation of the particles, however, is not alone sufficient for crystalliza- tion. A hot saturated saline solution, when screened from all agitation, will contract by cooling into a volume much smaller that what it occupies in the solid state, without crystal- lizing. Hence the molecules must not only be brought within a certain limit of each other, for their concreting into crystals ; but they must also change the direction of their poles from the fluid collocation to their position in the solid state. This reversion of the poles may be effected, 1st, By contact of any part of the fluid with a point of a solid, of similar composition, previ- ously formed. 2d, Vibratory motions com- municated, either from the atmosphere or any other moving body, by deranging, however slightly, the fluid polar direction, will instantly determine the solid polar arrangement, when the balance had been rendered nearly even by previous removal of the interstitial fluid. On this principle we explain the regular figures which particles of dust or iron assume, when they are placed on a vibrating plane, in the neighbourhood of electrized or magnetized bodies. 3d. Negative or resinous voltaic elec- tricity instantly determines the crystalline ar- rangement, while positive voltaic electricity counteracts it. On this subject I beg to refer the reader to an experimental paper which I published in the fourth volume of the Journal of Science, p. 106. Light also favours crys- tallization, as is exemplified with camphor dissolved in spirits, which crystallizes in bright and rcdissolves in gloomy weather. It might be imagined, that the same body would always concrete in the same, or at least in a similar crystalline form. This position is true, in general, for the salts crystallized in the laboratory ; and on this uniformity of figure, one of the principal criteria between different salts depends. But even these forms are liable to many modifications, from causes apparently slight ; and in nature, we find fre- quently the same chemical substance crystal- lized in forms apparently very dissimilar. Thus, carbonate of lime assumes the form of a rhomboid, of a regular hexaheural prisin, of a solid terminated by 12 scalene angles, or of a dodecahedron with pentagonal faces, &c. Bisulphuret of iron or martial pyrites produces sometimes cubes and sometimes regular octo- hedrons, at one time dodecahedrons with pen- tagonal faces, at another icosahedrons with tri- angular faces, &c. While one and the same substance lends it- self to so many transformations, we meet with very different substances, which present abso- lutely the same form. Thus fluate of lime, muriate of soda, sulphuret of iron, sulphuret of lead, &c. crystallize in cubes, under cer- tain circumstances ; and in other cases, the same minerals, as well as sulphate of alumina and the diamond, assume the form of a re- gular octohedron. Rome de 1'Isle first referred the study of crystallization to principles conformable to ob- servation. He arranged together, as far as possible, crystals of the same nature. Among the different forms relative to each species, he chose one as the most proper, from its sim- plicity, to be regarded as the primitive form ; and by supposing it truncated in different ways, he deduced the other forms from it, and determined a gradation, a series of transitions between this same form and that of polyhe- drons, which seemed to be still farther removed from it. To the descriptions and figures which he gave of the crystalline forms, he added the results of the mechanical measurement of their principal angles, and showed that these angles w.re constant in each variety. The illustrious Bergmann, by endeavouring to penetrate to the mechanism of the struc- ture of crystals, considered the different forms relative to one and the same substance as produced by a superposition of planes, some- times constant and sometimes variable, and decreasing around one and the same pri- mitive form, fie applied this primary idea to a small number of crystalline forms, and verified it with respect to a variety of calcare- ous spar f by fractures, which enabled him to ascertain the position of the nucleus, or of the primitive form, and the successive order of the laminas covering this nucleus. Bergmann, however, stopped here, and did not trouble himself either with determining the laws of structure, or applying calculation to it. It was a simple sketch of the most prominent point of view in mineralogy, but in which we see the hand of the same master who so success- fully filled up the outlines of chemistry. In the researches which M. Haliy under- took, about the same period, on the structure of crystals, he proposed combining the form and dimensions of integrant molecules with simple and regular laws of arrangement, and sub- mitting these laws to calculation. This work- produced a mathematical theory, which he reduced to analytical formulae, representing f This is what has been called dent de cochon, but which M. Haiiy calls mctastatic. CRY 373 CRY every possible case, and the application of which to known forms leads to valuations of angles, Constantly agreeing with observation. Theory of the Structure of Crystals. Primitive forms. The idea of referring to one of the same primitive forms, all the forms which maybe assumed by a mineral substance, of which the rest may be regarded as being modifications only, has frequently suggested itself to various philosophers, who have made crystallography their study. The mechanical division of minerals, which is the only method of ascertaining their true primitive form, proves that this form is inva- riable while we operate upon the same sub- stance, however diversified or dissimilar the forms of the crystals belonging to this sub- stance may be. Two or three examples will serve to place this truth in its proper light. Take a regular hexahedral prism of carbo- nate of lime (PI. viii. figs. 1. and 2). If we try to divide it parallel to the edges, from the contours of the bases, we shall find, that three of these edges taken alternately in the upper part, for instance, the edges If, c d, b m, may be referred to this division : and in order to succeed in the same way with respect to the inferior base, we must choose not the edges, /'/', c' d', b'm', which correspond with the preceding, but the intermediate edges d' f\ V c, I' m'. The six sections will uncover an equal num- ber of trapeziums. Three of the latter are re- presented upon fig. 2. viz. the two which in- tercept the edges, If, c d, and are designated by p p o o, aakk, and that which intercepts the lower edge d'f, and which is marked by the letters n n ii. Each of these trapeziums will have a lustre and polish, from which we may easily ascer- tain, that it coincides with one of the natural joints of which the prism is the assemblage. We shall attempt in vain to divide the prism in any other direction. But if we continue the division parallel to the first sections, it will happen, that on one hand the surfaces of the bases will always become narrower, while, on the other hand, the altitudes of the lateral planes will decrease ; and at the term at which the bases have disappeared, the prism will be changed into a dodecahedron (fig. 3.) with pentagonal faces, six of which, such as ooiOe, o I k i i, &c. will be the residues of the planes of the prism ; and the six others E A I o 0, O A ' K i i, &c. will be the immediate result of the mechanical division. Beyond this same term, the extreme faces will preserve their figure and dimensions, while the lateral faces will incessantly dimi- nish in height, until the points 6, fc, of the pentagon o I k i i, coming to be confounded with the points i , and so on with the other points similarly situated, each pentagon will be reduced to a simple triangle, as we see in fig. 4.* Lastly, when new sections have obliterated these triangles, so that no vestige of the surface of the prism remains (fig. 1), we shall have the nucleus or the primitive form, which will be an obtuse rhomboid (fig. 5.), the grand angle of which E A I orE O I, is 101 32' 13"f. If we try to divide a crystal of another species, we shall have a different nucleus. For instance, a cube of fluate of lime will give a regular octohedron, which we succeed in ex- tracting by dividing the cube upon its eight solid angles, which will in the first place discover eight equilateral triangles, and we may pursue the division, always parallel to the first sections, until nothing more remains of the faces of the cube. The nucleus of the crystals of sulphate of barytes will be a straight prism with rhombous bases; that of the crystals of phosphate of lime, a regular hex- ahedral prism ; that of sulphuretted lead, a cube, &c. ; and each of these forms will be constant, relative to the entire species, in such a manner, that its angles will not undergo any appreciable variation. Having adopted the word primitive form in order to designate the nucleus of crystals, M. Hatty calls secondary forms, such varieties as differ from the primitive form. In certain species, crystallization also pro- duces this last form immediately. We may define the primitive form, a solid of a constant form, engaged symmetrically in all the crystals of one and the same species, and the faces of which follow the directions of the lamina? which form these crystals. The primitive forms hitherto observed are reduced to six, viz. the parallelopipedon, the octohedron, the tetrahedron, the regular hex- ahedral prism, the dodecahedron with rhom- bous planes all equal and similar, and the dodecahedron with triangular planes, com- posed of two straight pyramids joined base to base. * The points which are confounded, two and two, upon this figure, are each marked with the two letters which served to designate them when they were separated, as in fig. 3. f It is observed, that each trapezium, such as pp o o (fig. 2.), uncovered by the first sec- tions, is very sensibly inclined from the same quantity, as well upon the residue pp deb m of the base, as upon the residue o of'V of the adjacent plane. Setting out from this equality of inclinations, we deduce from it by calcula- tion, the value of the angles with the precision of minutes and seconds, which mechanical measurements are not capable of attaining. CRY 374 CRY Forms of integrant Molecules. The nu- cleus of a crystal is not the last term of its mechanical division. It may always be sub- divided parallel to its different faces, and sometimes in other directions also. The whole of the surrounding substance is capable of being divided by strokes parallel to those which take place with respect to the primitive form. If the nucleus be a parallelopipedon, which cannot be subdivided except by blows parallel to its faces, like that which takes place with respect to carbonated lime, it is evident that the integrant molecule will be similar to this inucleus itself. But it may happen that the parallelopipedon admits of further sections in other directions than the former. We may reduce the forms of the integrant molecules of all crystals to three, which are, the tetrahedon, or the simplest of the pyra- mids ; the tiiangular prism, or the simplest of all the prisms ; and the parallelopipedon, or the simplest among the solids, which have their faces parallel two and two. And since four planes at least are necessary for circum- scribing a space, it is evident that the three forms in question, in which the number of faces is successively four, five, and six, have still, in this respect, the greatest possible simplicity. Laws to -which the Structure is subjected. After having determined the primitive forms, and those of the integrant molecules, it remains to inquire into the laws pursued by these molecules in their arrangement, in order to produce those regular kinds of envelopes, which disguise one and the same primitive form in so many different ways. Now, observation shows, that this surround- ing matter is an assemblage of laminae, which, setting out from the primitive form, decrease in extent, both on all sides at once, and some- times in certain particular parts only. This decrement is effected by regular subtractions of one or more rows of integrant molecules ; and the theory, in determining the number of these rows by means of calculation, succeeds in representing all the known results of crys- tallization, and even anticipates future disco- veries, indicating forms which, being still hypothetical only, may one day be presented to the inquiries of the philosopher. Decrements on the Edges Let s s' (fig. 6. pi. viii.) be a dodecahedron with rhombic planes. This solid, which is one of the six primitive forms of crystals, also presents itself occasionally as a secondary form, and in this case it has, as a nucleus, sometimes a cube and sometimes an octohedron. Supposing the nucleus to be a cube : In order to extract this nucleus, it is suffi- cient successively to remove the six solid angles composed of four planes, such as s> r, tf, &c. by sections adapted to the direction of the small diagonals. These sections will display as many squares A E O I, E O O' E', I O O' I' (fig. 7.), &c. which will be the faces of the cube. Let us conceive that each of these faces is subjected to a series of decreasing laminas solely composed of cubic molecules, and that every one of these laminae exceeds the suc- ceeding one, towards its four edges, by a quantity equal to one course of these same molecules. Afterwards we shall designate the decreasing laminae which envelope the nucleus, by the name of laminae of superposition. Now, it is easy to conceive that the different series will produce six quadrangular pyramids, si- milar in some respects to the quadrangular steps of a column, which will rest on the faces of the cube. Three of these pyramids are represented in fig. 8. and have their sum- mits in s, tf, r'. Now, as there are six quadrangular pyra- mids, we shall therefore have twenty-four triangles, such as, O s 1, 1 1, &c. But be- cause the decrement is uniform from s to , and so on with the rest ; the triangles taken two and two are on a level, and form a rhomb s O 1 1. The surface of the solid will there- fore be composed of twelve equal and similar rhombs ; i. e. this solid will have the same form with that which is the subject of the problem. This structure takes place, although imperfectly, with respect to the crystals called boracic spars. The dodecahedron now under consideration is represented by fig. 8. in such a way that the progress of the decrement may be perceived by the eye. On examining the figure attentively, we shall find that it has been traced on the supposition, that the cubic nucleus has on each of its edges 17 ridges of molecules ; whence it follows, that each of its faces is composed of 289 facets of molecules, and that the whole solid is equal to 4913 molecules. On this hypothesis, there are eight laminae of super- position, the last of which is reduced to a simple cube, whose edges determine the num- bers of molecules which form the series 15, 13, 11, 9, 7, 5, 3, 1, the difference being 2, because there is one course subtracted from each extremity. Now, if instead of this coarse kind of ma- sonry, which has the advantage of speaking to the eye, we substitute in our imagination the infinitely delicate architecture of nature, we must conceive the nucleus as being composed of an incomparably greater number of imper- ceptible cubes. In this case, the number of laminae of superposition will also be be- yond comparison greater than on the pre- ceding hypothesis. By a necessary conse- quence, the furrows which form these laminas by the alternate projecting and re-entering of their edges, will not be cognizable by our CRY 375 CRY senses; and this is what takes place in the polyhedra which crystallization has produced at leisure, without being disturbed in its pro- gress. M. Ha'iiy calls decrements in breadth, those in which each lamina has only the height of a molecule ; so that their whole effect, by one two, three, &c. courses, is in the way of breadth. Decrements in height are those in which each lamina, exceeding only the follow- ing one by a single course in the direction of the breadth, may have a height double, triple, quadruple, &c. to that of a molecule : this is expressed by saying that the decrement takes place by two courses, three courses, &c. in height. The light which the theory of definite pro- portions has thrown upon chemistry, the mechanical views by which the atomic phi- losophy accounts for fixed proportions, the use which has been made of these views to repre- sent bodies composed of a determinate number of atoms, engaged M. Mitscherlich to examine the following problems : Different elements being combined with the same number of atoms of one element, or of several different elements, have they the same crystalline/orw ? Is the identity of the crystalline form deter- mined only by the number of atoms ? Is this form independent of the chemical nature of the elements. The trials which he has made, appear to him to demonstrate that certain different' elements, combined with the same number of one or of several elements, affect the same crystalline form ; and that chemical elements in general may in this respect be classed in groups. He gives the epithet isomorphous to those elements which belong to the same group, in order to express this quality of the elements by a technical term. Thus, every arseniate, he says, has a phosphate, which corresponds to it, composed according to the same proportions, combined with the same atoms of water of crystallization, and which at the same time has the same physical qua- lities. In a word, the two series of salts with the phosphorous and phosphoric, arsenious and arsenic acids, differ in no respect, except that the radical of the acid of one series is phosphorus, and of the other is arsenic. The conclusion at which he arrives, is : The same number of atoms combined in the same manner produces the same crystalline form ; and the same crystalline form is independent of the chemical nature of the atoms, being de- termined only by their number and relative position. Ann. de Chim. et Phys. xix. 350. Mr. Brooke, after urging several strong ob- jections against the theory advanced by M. Mitscherlich, says, that he is informed the author has lately abandoned it, which however there is good reason to doubt. We are indebted to Dr. Wollaston for ideas on the ultimate cause of crystalline forms, equally ingenious and profound. They were communicated to the Royal Society, and pub- lished in their transactions for the year 1813. Among the known forms of crystallized bodies, there is no one common to a greater number of substances than the regular ccto- hedron, and no one in which a corresponding difficulty has occurred with regard to deter- mining which modification of its form is to be considered as primitive ; since in all these substances the tetrahedron appears to have equal claim to be received as the original from which all then: other modifications are to be derived. The relation of these solids to each other is most distinctly exhibited to those who are not much conversant with crystallography, by assuming the tetrahedron as primitive, for this may immediately be converted into an octohedron by the removal of four smaller tetrahedrons from its solid angles. Plate ix. fig. 1. The substance which most readily admits of division by fracture into these forms, is fluor spar ; and there is no difficulty in obtaining a sufficient quantity for such experiments. But it is not, in fact, either the tetrahedron or the octohedron, which first presents itself as the ap- parent primitive form obtained by fracture. If we form a plate of uniform thickness by two successive divisions of the spar, parallel to ^ each other, we shall find the plate divisible into prismatic rods, the section of which is a rhomb of 70 32' and 109 28' nearly : and if we again split these rods transversely, we shall obtain a number of regular acute rhomboids, all similar to each other, having their super- ficial angles 60 and 120, and presentirg an appearance of primitive molecules, from which all the other modifications of such crystals might very simply be derived. And we find, moreover, that the whole mass of fluor might be divided into, and conceived to consist of, these acute rhomboids alone, which may be put together so as to fit each other without any intervening vacuity. But, since the solid thus obtained (as repre- sented fig 2.) may be again split by natural fractures at right angles to its axis (fig. 3), so that a regular tetrahedron may be detached from each extremity, while the remaining por- tion assumes the form of a regular octohedron; and since every rhomboid that can be obtained must admit of the same division into one octo- hedron and two tetrahedrons, the rhomboid can no longer be regarded as the primitive form ; and since the parts into which it is divisible are dissimilar, we are left in doubt which of them is to have precedence as primitive. In the examination of this question, whether we adopt the octohedron or the tetrahedron as the primitive form, since neither of them can fill space without leaving vacuities, there is a difficulty in conceiving any arrangement in which the particles will remain at rest : for, CRY 376 CRY whether we suppose, with the Abbe Haiiy, that the particles are tetrahedral with octohe- dral cavities, or, on the contrary, octohedral particles regularly arranged with tetrahedral cavities, in each case the mutual contact of adjacent particles is only at their edges ; and although in such an arrangement it must be admitted that there may be an equilibrium, it is evidently unstable, and ill adapted to form the basis of any permanent crystal . With respect to fluor spar, and such other substances as assume the octohedral and tetra- hedral forms, all difficulty is removed, says Dr. Wollaston, by supposing the elementary particles to be perfect spheres, which, by mu- tual attraction, have assumed that arrange- ment which brings them as near to each other as possible. The relative position of any number of equal balls in the same plane, when gently pressed together, forming equilateral triangles with each other (as represented perspectively in fig. 4.), is familiar to every one ; and it is evi- dent that, if balls so placed were cemented to- gether, and the stratum thus formed were afterwards broken, the straight lines in which they would be disposed to separate would form angles of 60 with each other. If a single ball were placed any where at rest upon the preceding stratum, it is evident that ^ it would be in contact with three of the lower balls (as in fig. 5.), and that the lines joining the centres of four balls so in contact, or the planes touching their surfaces, would include a regular tetrahedron, having all its equilateral triangles. The construction of an octohedron, by means of spheres alone, is as simple as that of the tetrahedron. For, if four balls be placed in contact on the same plane, in form of a square, then a single ball resting upon them in the centre, being in contact with each pair of balls, will present a triangular face rising from each side of the square, and the whole together will represent the superior apex of an octohedron ; so that a sixth ball similarly placed underneath the square will complete the octohedral group, % 6. "here is one observation with regard to these f-r.-r.is that will appear paradoxical, namely, triat a structure, which in this case was b?gun upon a square foundation, is really mncafly the same as that which is begun up~n the triangular basis. But if we lay the octohedral group, which consists of six balls, on one of its triangular sides, and, consequently, with an opposite triangular face uppermost, the two groups, consisting of three balls each, are then situated precisely as they would be found in two adjacent strata of the triangular arrangement. Hence, in this position, we may readily convert the octohedron into a regular tetrahedron, by addition of four more balls (fig 7- ) One placed on the top of the three that are uppermost forms the apex ; and if the triangular base, on which it rests, be enlarged hy addition of three more balls, regularly dis- posed around it, the entire group of ten balls will then be found to represent a regular tetra- hedron. For the purpose of representing the acute rhomboid, two balls must be applied at opposite sides of the smallest octohedral group, as in fig. 9. And if a greater number of balls be placed together, fig. 10. and 11. in the same form, then a complete tetrahedral group may be removed from each extremity, leaving a cen- tral octohedron, as maybe seen in fig. 11. which corresponds to fig. 3. We have seen, that, by due application of spheres to each other, all the most simple forms of one species of crystal will be pro- duced, and it is needless to pursue any other modifications of the same form, which must result from a series of decrements produced according to known laws. Since then the simplest arrangement of the most simple solid that can be imagined affords so complete a solution of one of the most dif- ficult questions in crystallography, we are naturally led to inquire what forms would probably occur from the union of other solids most nearly allied to the sphere. And it will appear, that by the supposition of elementary particles that are spheroidical, we may frame conjectures as to the origin of other angular solids well known to crystallographers. The obtuse Rhomboid. If we suppose the axis of our elementary spheroid to be its shortest dimension, a class of solids will be formed which are numerous in crystallography. It has been remarked above, that by the natural grouping of sphe- rical particles, fig. 10. one resulting solid is an acute rhomboid, similar to that of fig. 2. having certain determinate angles, and its greatest dimension in the direction of its axis. Now, if other particles having the same rela- tive arrangement be supposed to have the form of oblate spheroids, the resulting solid, fig. 12. will still be a regular rhomboid ; but the mea- sures of its angles will be different from those of the former, and will be more or less obtuse according to the degree of oblateness of the primitive spheroid. It is at least possible that carbonate of lime and other substances, of which the forms are derived from regular rhomboids as their pri- mitive form, may, in fact, consist of oblate spheroids as elementary particles. Hexagonal Prisms. If our elementary spheroid be on the con- trary oblong, instead of oblate, it is evident that, by mutual attraction, their centres will approach nearest to each other when their axes are parallel, and their shortest diameters in the same plane (fig 13). The manifest conse- quence of this structure would be, that a solid CRY 377 CRY so formed would be liable to split into plates at right angles to the axes, and the plates would divide into prisms of three or six sides with all their angles equal, as occurs in phos- phate of lime, beryl, &c. It inay farther be observed, that the pro- portion of the height to the base of such a prism must depend on the ratio between the axes of the elementary spheroid. The Cube. Let a mass of matter be supposed to consist of spherical particles all of the same size, but of two different kinds in equal numbers, repre- sented by black and white balls ; and let it be required that, in their perfect intermixture, every black ball shall be equally distant from all surrounding white balls, and that all adja- cent balls of the same denomination shall also be equidistant from each other. The doctor shows, that these conditions will be fulfilled if the arrangement be cubical, and that the par- tides will be in equilibria. Fig. 14. represents a cube so constituted of balls, alternately black and white throughout. The four black balls are all in view. The distances of their centres being every way a superficial diagonal of the cube, they are equidistant, and their configura- tion represents a regular tetrahedron ; and the same is the relative situation of the four white balls. The distances of dissimilar adjacent balls are likewise evidently equal ; so that the conditions of their union are complete, as far as appears in the small group : and this is a cor- rect representative of the entire mass, that would be composed of equal and similar cubes. There remains one observation with regard to the spherical form of elementary particles, whether actual or virtual, that must be regard- ed as favourable to the foregoing hypothesis, namely, that many of those substances which we have most reason to think simple bodies, as among the class of metals, exhibit this further evidence of their simple nature, that they crys- tallize in the octahedral form as they would do if their particles were spherical. But it must, on the contrary, be acknowledged that we can at present assign no reason why the same appearance of simplicity should take place in fluor spar, which is presumed to con- tain at least two elements ; and it is evident, that any attempts to trace a general corre- spondence between the crystallographical and supposed chemical elements of bodies, must, in the present state of these sciences, be premature. Any sphere when not compressed will be sur- rounded by twelve others, and, consequently by a slight degree of compression, will be convert- ed into a dodecahedron, according to the most probable hypothesis of simple compression. The instrument for measuring the angles of crystals is called a goniometer, of which there are two kinds. 1. The goniometer of M. Ca- rangeau, used by M. Haiiy, consists of two pa- rallel blades, jointed like those of scissars, and capable of being applied to a graduated semi- circular sector, which gives the angle to which the joint is opened, in consequence of the pre- vious apposition of the two blades to the angle of the crystal. 2. The reflective goniometer of Dr. Wollaston ; an admirable invention, which measures the angles of the minutest pos- sible crystals with the utmost precision. An account of this beautiful instrument may be found in the Phil. Trans, for 1809, and in Tilloch's Magazine for February 1810, vol. 35. Mr. William Phillips published, in the 2d volume of the Geological Transactions, an elaborate series of measurements with this goniometer. A striking example of the power of this instrument in detecting the minutest forms with precision was afforded by its appli- cation to a crystalline jet-black sand, which Dr. Clark got from the island Jean Mayen, in the Greenland seas. " Having therefore," says Dr. Clarke, " selected a crystal of this form, but so exceedingly minute as scarcely to be discernible to the naked eye, I fixed it upon the moveable plane of Dr. Wollaston's reflect- ing goniometer. A double image was reflected by one of the planes of the crystal, but the image reflected by the contiguous plane was clear and perfectly perceptible, by which I was enabled to measure the angle of inclination ; and after repeating the observation several times, I found it to equal 92 or 92^. Hence it is evident that these crystals are not zircons, although they possess a degree of lustre quite equal to that of zircon. In this uncertainty, I sent a small portion of the sand to Dr. Wol- laston, and requested that he would himself measure the angle of the particles exhibiting splendent surfaces. Dr. Wollaston pronounced the substance to be pyroxene; having an angle, according to his observation, of 92^. He also informed me that the sand was simi- lar to that of Bolsenna in Italy." Such a ready means of minute research forms a de- lightful aid to the chemical philosopher, as well as the mineralogist. M. Haiiy, by a too rigid adherence to the principle of geome- trical simplicity, obtained an erroneous deter- mination of the angles in the primary form of carbonate of lime, amounting to 36 mi- nutes of a degree. And by assigning to the magnesian and ferriferous carbonates of lime the same angle as to the simple carbonate, the error became still greater, as will appear from the following comparative measure- ments. CRY 378 CRY Carbonate of lime, Magnesian carbonate. Ferriferous carbonate, Observed angle by Dr. Wollaston's Theoretic angle, goniometer. 105o 5' 104o 28' 40" 106 15 107 104 28 40 104 28 40 Error. 36' 20' 1 46 20 2 31 20 M. Ha'uy will no doubt accommodate his results to these indications of Dr. Wollaston's goniometer, and give his theory all the per- fection which its scientific value and elegance deserve. M. Beudant has lately made many expe- riments to discover why a saline principle of a certain kind sometimes impresses its crystal- line form upon a mixture in which it does not, by any means, form the greatest part; and also with the view of determining, why one saline substance may have such an astonish- ing number of secondary forms as we some- times meet with. The presence of urea makes common salt take an octohedral form, although in pure water it crystallizes in cubes similar to its primitive molecules. Sal ammoniac, which crystallizes in pure water in octohedrons, by means of urea crystallizes in cubes. A very slight excess or deficiency of base in alum causes it to assume either cubical or octohe- dral secondary forms ; and these forms are so truly secondary, that an octohedral crystal of alum, immerged in a solution which is richer in respect to its basis, becomes enveloped with crystalline layers, which give it at length the form of a cube. The crystalline form^in muddy solutions acquires greater simplicity, losing all those additional facets, which would otherwise mo- dify their predominant form. In a gelatinous deposite, crystals are rarely found in groups, but almost always single, and of a remarkable sharpness and regularity of form ; and they do not undergo any variations but those which may result from the chemical action of the substance forming the deposite. Common salt crystallized in a solution of borax acquires truncations at the solid angles of its cubes ; and alum crystallized in muriatic acid takes a form which M. Beudant has never been able to obtain in any other manner. 30 or 40 per cent, of sulphate of copper may be united to the rhomboidal crystallization of sulphate of iron, but it reduces this sulphate to a pure rhomboid, without any truncation either of the angles or the edges. A small por- tion of acetate of copper reduces sulphate of iron to the same simple rhomboidal form, not- withstanding that this form is disposed to be- come complicated with additional surfaces. Sulphate of alumina brings sulphate of iron to a rhomboid, with the lateral angles only trun- cated, or what M. Ha'uy calls his variite uni- taire ; and whenever this variety of green vitriol is found in the market, where it is very common, we may be sure, according to M. Beudant, that it contains alumina. Natural crystals mixed with foreign sub- stances are in general more simple than others, as is shown in a specimen of axinite or violet schorl of Dauphine, one extremity of which being mixed with chlorite is reduced to its primitive form ; while the other end, which is pure, is varied by many facets produced by different decrements. In a mingled solution of two or more salts, of nearly equal solubility, the crystallization of one of them may be sometimes determined by laying or suspending in the liquid a crystal of that particular salt. M. Le Blanc states, that, on putting into a tall and narrow cylinder, crystals at different heights, in the rnidst of their saturated saline solution, the crystals at the bottom increase faster than those at the surface, and that there arrives a period when those at the bottom con- tinue to enlarge, while those at the surface diminish and dissolve. Those salts which are apt to give up their water of crystallization to the atmosphere, and of course become efflorescent, may be preserved by immersion in oil, and subsequent wiping of their surface. In the Wernerian language of crystalliza- tion, the following terms are employed: When a secondary form differs from the cube, the octohedron, &c. only in having several of its angles or edges replaced by a face, this change of the geometrical form is called a truncation. The alteration in the principal form produced by two new faces inclined to one another, and which replace by a kind of bevel, an angle, or an edge, is called a levelment. When these new faces are to the number of three or more, they produce what Werner termed a pointing, or aciimination. When two faces unite by an edge in the manner of a roof, they have been called culmination. Replacement is occasion- ally used for bevelment. The reader will find some curious observa- tions on crystallization, by Mr. J. F. Daniell, in the 1st vol. of the Journal of Science. Professor Mohs, successor to Werner in Freyberg, Dr. Weiss, professor of mineralogy in Berlin, and M. Brochant, professor of mineralogy in Paris, have each recently pub- lished systems of mineralogy. Pretty copious details, relative to the first, are given in the 3rd volume of the Edinburgh Philosophical Journal. A complete exposition of this system will be found in M. Haidinger's able translation of Mohs. In a paper in the Journal de Physique, M. Le Blanc gives instructions for obtaining crystals of large size. His method is to em- CRY 379 CYA ploy flat glass or china vessels : to pour into these the solutions boiled down to the point of crystallization : to select the neatest of the small crystals formed, and put them into ves- sels with more of the mother- water of a solu- tion that has been brought to crystallize con- fusedly : to turn the crystals at least once a- day ; and to supply them from time to time with fresh mother-water. If the crystals be laid on their sides, they will increase most in length; if on their ends, most in breadth. When they have ceased to grow larger, they must be taken out of the liquor, or they will soon begin to diminish. It may be observed in general, that very large crystals are less transparent than those that are small. The crystals of metals may be obtained by fusing them in a crucible with a hole in its bottom, closed by a stopper, which is to be drawn out after the vessel has been removed from the fire, and the surface of the metal has begun to congeal. The same effect may be observed if the metal be poured into a plate or dish, a little inclined, which is to be suddenly inclined in the opposite direction, as soon as the metal begins to congeal round its edges. In the first method, the fluid part of the metal runs out of the hole, leaving a kind of cup lined with crystals: in the latter way, the superior part, which is fluid, runs off, and leaves a plate of metal studded over with crys- tals. The operation of crystallizing, or crystalli- zation, is of great utility in the purifying of various saline substances. Most salts are suspended in water in greater quantities at more elevated temperatures, and separate more or less by cooling. In this property, and like- wise in the quantity of salt capable of being suspended in a given quantity of water, they differ greatly from each other. It is therefore practicable in general to separate salts by due management of the temperature and evapora- tion. For example, if a solution of nitre and common salt be evaporated over the fire, and a small quantity be now and then taken out for trial, it will be found, at a certain period of the concentration, that a considerable portion of salt will separate by cooling, and that this salt is for the most part pure nitre. When this is seen, the whole fluid may be cooled to separate part of the nitre, after which, evapo- ration may be proceeded upon as before. This manipulation depends upon the different pro- perties of the two salts with regard to their solubility and crystallization in like circum- stances. For nitre is considerably more solu- ble in hot than in cold water, while common salt is scarcely more soluble in the one case than in the other. The common salt con- sequently separates in crystals as the evapora- tion of the heated fluid goes on, and is taken out with a ladle from time to time, whereas the nitre Is separated by successive coolings at proper periods. CUBE ORE. Hexahedral Olivenite. Wurfelerz. Wern. This mineral has a pis- tacio- green colour, of various shades. It occurs massive, and crystallized in the perfect cube ; in a cube with four diagonally opposite angles truncated ; or in one truncated on all its angles; or finally, both on its edges and angles. The crystals are small, with planes smooth and splendent. Lustre glistening. Cleavage parallel with the truncations of the angles. Translucent. Streak straw -yellow. Harder than gypsum. Easily frangible. Sp. gr. 3.0. Fuses with disengagement of arsenical vapours. Its constituents are, 31 arsenic acid, 45.5 oxide of iron, 9 oxide of copper, 4 silica, and 10.5 water, by Chenevix. Vauquelin's analysis gives no copper nor silica, but 43 iron, 18 arsenic acid, 2 to 3 carbonate of lime, and 32 water. It is found in veins, accompanied with iron-shot quartz, in Tincroft, and various other mines of Cornwall, and at St. Leonard in the Haut-Vienne in France. As an arseniate of iron, it might be ranked among the ores of either this metal or arsenic. Jameson. CUDBEAR. See ARCHIL. CUPEL. A shallow earthen vessel, some- what resembling a cup, from which it derives its name. It is made of phosphate of lime, or the residue of burned bones rammed into a mould, which gives it its figure. This vessel is used in assays wherein the precious metals are fused with lead, which becomes converted into glass, and carries the impure alloy with it. See ASSAY. CUPELLATION. The refining of gold by scorification with lead upon the cupel, is called cupellation- See ASSAY. CURD. The coagulum which separates from milk upon the addition of acid or other substances. See MILK. CYANITE, OR KYANITE. Disthene of Haiiy. Its principal colour is Berlin-blue, which passes into grey and green. It occurs massive and disseminated, also in distinct con- cretions. The primitive form of its crystals is an oblique four - sided prism ; and the se- condary forms are, an oblique four-sided prism, truncated on the lateral edges, and a twin crys- tal. The planes are streaked, splendent, and pearly. Cleavage threefold. Translucent or transparent Surface of the broader lateral planes as hard as apatite ; that of the angles, as quartz. Easily frangible. Spec. grav. 3.5. When pure it is idio-electric. Some crystals by friction acquire negative, others positive electricity; hence, Haiiy's name. It is in- fusible before the blowpipe. It consists, by Klaproth, of 43 silica, 56.5 alumina, 0-50 iron, and a trace of potash. It occurs in the granite and mica slate of primitive mountains. It is found near Banchory in Aberdeenshire, and Bocharm in Banffshire ; at Airolo on St. Gothard, and in various countries of Eu- rope, as well as in Asia and America. It is CYA CYA cut and polished in India as an inferior sort of sapph ire. Jameson. CYANOGEN. The compound base of prussic acid. The term signifies the producer of Hue. This production of blue is never the result of the direct action of this substance on any other single body; but an indirect and unexplained operation of it in conjunction with iron, hydrogen, and oxygen. The same reason which leads to the term cyanogen would war- rant us in calling it leucogen, erythrogen, or chlorogen ; for it produces white, red, or green, with other metals, if it produce blue with iron. Yet, deference is due to the nomenclature of so distinguished a chemist as M. Gay Lussac. Cyanogen, like chlorine and iodine, by its ac- tion on potassium, produces flame, and like them is acidified by hydrogen. Its discovery and investigation do the highest honour to M. Gay Lussac. Cyanogen is obtained by decomposing the cyanide of mercury by heat. But as this varies in its composition, we shall begin by describing its formation. By digesting red oxide of mercury with prussian blue and hot water, we obtain a cyanide perfectly neutral, which crystallizes in long four-sided prisms, truncated obliquely. By repeated solutions and crystallizations, we may free it from a small portion of adhering iron. But M. Gay Lussac prefers boiling it with red oxide of mercury, which completely precipitates the oxide of iron, and he then saturates the excess of oxide of mercury with a little prussic acid, or a little muriatic acid. The cyanide thus formed is decomposed by heat to obtain the radical. For common ex- periments we may dispense with these precau- tions. When this cyanide is boiled with red oxide of mercury, it dissolves a considerable quan- tity of the oxide, becomes alkaline, crystallizes no longer in prisms, but in small scales, and its solubility in water appears a little increased. When evaporated to dryness, it is very easily charred, which obliges us to employ the heat merely of a water bath. This compound was observed by M. Proust. When decomposed by heat, it gives abundance of cyanogen, but mixed with carbonic acid gas. Proust says, that it yields ammonia, oil in considerable abundance, carbonic acid, azote, and oxide of carbon. He employed a moist cyanide. Had it been dry, the discovery of cyanogen could hardly have escaped him. The cyanide of mer- cury, when neutral and quite dry, gives nothing but cyanogen ; when moist, it furnishes only carbonic acid, ammonia, and a great deal of prussic acid vapour. When we employ the cyanide made with excess of peroxide, the same products are obtained, but in different proportions, along with azote, and a brown liquid, which Proust took for an oil, though it is not one in reality. Hence, to obtain pure cyanogen, we must employ the neutral cyanide in a state of perfect dryness. The other mer- curial compound is not, however, simply a sub-cyanide. It is a compound of oxide of mercury and the cyanide, analogous to the brick-coloured precipitate obtained by adding a little potash to the solution of deutochloride of mercury (corrosive sublimate), which is a triple compound of chlorine, oxygen, and mer- cury, or a binary compound of oxide of mer- cury with the chloride of that metal. These compounds might be called oxycyanide and oxy chloride of mercury. When the simple mercurial cyanide is ex- posed to heat in a small glass retort, or tube, shut at one extremity, it soon begins to blacken. It appears to melt like an animal matter, and then the cyanogen is disengaged in abundance. This gas is pure from the beginning of the process to the end, provided always that the heat be not very high ; for if it were suffi- ciently intense to melt the glass, a little azote would be evolved. Mercury is volatilized with a considerable quantity of cyanide, and there remains a charry matter of the colour of soot, and as light as lampblack. The cyanide of silver gives out likewise cyanogen when heated ; but the mercurial cyanide is prefer- able to every other. Cyanogen is a permanently elastic fluid. Its smell, which it is impossible to describe, is very strong and penetrating. Its solution in water has a very sharp taste. The gas burns with a bluish flame mixed with purple. Its specific gravity, compared to that of air, is 1.8064. M. Gay Lussac obtained it by weigh- ing at the same temperature, and under the same pressure, a balloon of about 2| litres (152.56 cubic inches), in which the vacuum was made to the same degree, and alternately full of air and cyanogen. 100 cubic inches weigh therefore 55.1295 grains. Cyanogen is capable of sustaining a pretty high heat, without being decomposed. Water, with which M. Gay Lussac agitated it for some minutes, at the temperature of 68, ab- sorbed about 4-j times its volume. Pure alcohol absorbs 23 times its volume. Sul- phuric ether and oil of turpentine dissolve at least as much as water. Tincture of litmus is reddened by cyanogen. On heating the solution the gas is disengaged, mixed with a little carbonic acid, and the blue colour of the litmus is restored. The carbonic acid proceeds no doubt from the decomposition of a small quantity of cyanogen and water. It deprives the red sulphate of manganese of its colour, a property which prussic acid does not possess. This is a proof that its elements have more mobility than those of the acid. In the dry way, it separates the carbonic acid from the carbonates. Phosphorus, sulphur, and iodine, may be sublimed by the heat of a spirit-lamp in cy- anogen, without occasioning any change on it. Its mixture with hydrogen was not altered by CYA 381 CYA the same temperature, or by passing electrical sparks through it Copper and gold do not combine with it ; but iron, when heated almost to whiteness, decomposes it in part. The me- tal is covered with a slight coating of charcoal, and becomes brittle. The undecomposed por- tion of the gas is mixed with azote (contains free azote). In one trial the azote constituted 0.44 of the mixture, but in general it was less. Platinum, which had been placed beside the iron, did not undergo any alteration. Neither its surface nor that of the tube was covered with charcoal like the iron. In the cold, potassium acts but slowly on cyanogen, because a crust is formed on its sur- face, which presents an obstacle to the mutual action. On applying the spirit-lamp, the po- tassium becomes speedily incandescent ; the absorption of the gas begins, the inflamed disc gradually diminishes, and when it disappears entirely, which takes place in a few seconds, the absorption is likewise at an end. Sup- posing we employ a quantity of potassium that would disengage 50 parts of hydrogen from water, we find that from 48 to 50 parts of gas have disappeared. On treating the residue with potash, there usually remain 4 or 5 parts of hydrogen, sometimes 10 or 12. M. Gay Lussac made a great number of experiments to discover the origin of this gas. He thinks that it is derived from the water which the cyanide of mercury contains when it has not been sufficiently dried. Prussic acid vapour is then produced, which, when decomposed by the potassium, leaves half its volume of hydro- gen. Potassium, therefore, absorbs a volume of pure cyanogen, equal to that of the hydro- gen which it would disengage from water. The compound of cyanogen and potassium is yellowish. It dissolves in water without effervescence, and the solution is strongly alka- line. Its taste is the same as that of hydro- cyanate or simple prussiate of potash, of which it possesses all the properties. The gas being very inflammable, M. Gay Lussac exploded it in Volta's eudiometer, with about 24 times its volume of oxygen. The detonation is very strong; and the flame is bluish, like that of sulphur burning in oxy- gen. Supposing that we operate on 100 parts of cyanogen, we find after the explosion a dimi- nution of volume, which amounts to from four to nine parts. When the residuum is treated with potash or barytes, it diminishes from 195 to 200 parts, which are carbonic acid gas. The new residuum, analyzed over water by hydrogen, gives from 94 to 98 parts of azote, and the oxygen which it contains, added to that in the carbonic acid, is equal (within four or five per cent) to that which has been em- ployed. Neglecting the small differences which pre- vent these numbers from having simple ratios to each other, and which, like the presence of hydrogen, depend upon the presence of a vari- able portion of prussic acid vapour in the cyanogen employed, proceeding from the water left in the cyanide of mercury, we may admit that cyanogen contains a sufficient quantity of carbon to produce twice its volume of carbonic acid gas ; that is to say, two volumes of the vapour of carbon, and one volume of azote condensed into a single volume. If that sup- position be exact, the density of the radical derived from it ought to be equal to the den- sity derived from experiment; but supposing the density of air to be 1.00, twice that of the vapour of Carbon is Azote, 08320 0-9691 1-8014 (0-8332) (0-9722) 1-8051 From the near agreement of these numbers, with the experimental density, we are entitled to conclude that M. Gay Lussac's analysis is correct. By adding a volume of hydrogen to a volume of cyanogen, we obtain two volumes of prussic acid vapour ; just as by adding a volume of hydrogen to a volume of chlorine, we obtain two volumes of muriatic acid gas. The same proportions hold with regard to the vapour of iodine, hydrogen, and hydriodic acid. Hence the sp. gr. of these three hydro- gen acids is exactly equal to half the sum of the densities of their respective bases and hy- drogen. This analogy was first established by M. Gay Lussac. It is now obvious that the action of po- tassium on cyanogen agrees with its action on prussic acid. We have seen that it absorbs 50 parts of the first, and likewise that it ab- sorbs 100 parts of the second, from which it separates 50 parts of hydrogen. But 100 parts of prussic acid vapour, minus 50 parts of hydrogen, amount exactly to 50 parts cy- anogen. Hence the two results agree perfectly, and the two compounds obtained ought to be identical, which agrees precisely with experi- ment. The analysis of cyanogen being of great im- portance, M. Gay Lussac attempted it like- wise by other methods. Having put cyanide of mercury into the bottom of a glass tube, he covered it with brown oxide of copper, and then raised the heat to a dull red. On heat- ing gradually the part of the tube containing the cyanide, the cyanogen was gradually dis- engaged, and passed through the oxide, which it reduced completely to the metallic state. On washing the gaseous products with aqueous potash, at different parts of the process, he obtained only from 0.19 to 0-30 of azote, in- stead of 0.33, which ought to have remained according to the preceding analysis. Presuming that some nitrous compound had been formed, he repeated the experiment, covering the oxide with a column of copper filings, which he kept at the same temperature as the oxide. With CYA CYA this new arrangement, the results were very singular ; for the smallest quantity of azote which he obtained during the whole course of the experiment was 32-7 for 100 of gas, and the greatest was 34-4. The mean of all the trials was, Azote, . 33-6 or nearly 1 Carbonic acid, 66-4 2 A result which shows clearly that cyanogen contains two volumes of the vapour of carbon, and one volume of azote. In another experiment, instead of passing the cyanogen through the oxide of copper, he made a mixture of one part of the cyanide of mercury, and 10 parts of the red oxide, and after introducing it into a glass tube, close at one end, he covered it with copper filings, which he raised first to a red heat. On heat- ing the mixture successively, the decomposi- tion went on with the greatest facility. The proportions of the gaseous mixture were less regular than in the preceding experiment. Their mean was, Azote, 34-6 instead of 33-3 Carbonic acid, 65-4 66-6 In another experiment he obtained, Azote, 32.2 Carbonic acid, 67-8 Now the mean of these results gives, Azote, 33-4 Carbonic acid, 66-6 No sensible quantity of water seemed to be formed during these analyses. This shows farther, that what has been called a prussiate of mercury is really a cyanide of that metal. When a pure solution of potash is intro- duced into this gas, the absorption is rapid. If the alkali be not too concentrated, and be not quite saturated, it is scarcely tinged of a lemon-yellow colour. But if the cyanogen be in excess, we obtain a brown solution, appa- rently carbonaceous. On pouring potash com- bined with cyanogen into a saline solution of a black oxide of iron, and adding an acid, we obtain prussian blue. It would appear from this phenomenon that the cyanogen is decom- posed the instant that it combines with the potash : but this conclusion is premature ; for when this body is really decomposed by means of an alkaline solution, carbonic acid is always produced, together with prussic acid and am- monia. But on pouring barytes into a solu- tion ot cyanogen in potash, no precipitate takes place, which shows that no carbonic acid is present. On adding an excess of quicklime, no trace of ammonia is perceptible. Since, then, no carbonic acid and ammonia have been formed, water has not been decomposed, and consequently no prussic acid evolved. How then comes the solution of cyanogen in potash to produce prussian blue, with a solution of iron and acid? The following is M. Gay Lussac's solution of this difficulty : The instant an acid is poured into the solu. tion of cyanogen in potash, a strong effer- vescence of carbonic acid is produced, and at the same time a strong smell of prussic acid becomes perceptible. Ammonia is likewise formed, which remains combined with the acid employed, and which may be rendered very sensible to the smell by the addition of quick- lime. Since therefore we are obliged to add an acid in order to form prussian blue, its formation occasions no farther difficulty. Soda, barytes, and strontites, produce the same effect as potash. We must therefore admit that cyanogen forms particular combi- nations with the alkalis, which are permanent till some circumstance determines the forma- tion of new products. These combinations are true salts, which may be regarded as ana- logous to those formed by acids. In fact cy- anogen possesses acid characters. It contains two elements, azote and carbon, the first of which is strongly acidifying, according to M. Gay Lussac. (Is it not as strongly alkalify- ing, with hydrogen, in ammonia ?) Cyanogen reddens the tincture of litmus, and neutralizes the bases. On the other hand, it acts as a simple body when it combines with hydrogen ; and it is this double function of a simple and compound body which renders its nomenclature so embarrassing. Be this as it may, the compounds of cyano- gen and the alkalis, which may be distin- guished by the term cyanides, do not separate in water, like the alkaline chlorides, (oxymu- riates), which produce chlorates and muriates. But when an acid is added, there is formed, 1st, Carbonic acid, which corresponds to the chloric acid ; 2d, Ammonia and prussic acid, which correspond to the muriatic. When the cyanide of potash is decomposed by an acid, there is produced a volume of car- bonic acid just equal to that of the cyanogen employed. What then becomes of the other volume of the vapour of carbon ; for the cya- nogen contains two, with one volume of azote ? Since there is produced, at the expense of the oxygen of the water, a volume of carbonic acid, which represents 1 volume of oxygen, 2 volumes of hydrogen must likewise have been produced. Therefore, neglecting the carbonic acid, there remains 1 volume vapour of carbon, 1 azote, 2 hydrogen ; and we must make these three elements com- bine in totality, so as to produce only prussic acid and ammonia. But the one volume of the vapour of carbon, with half a volume of azote, and half a volume of hydrogen, produces exactly 1 volume of prussic acid, while the volume and a half of hydrogen, and the half volume of azote remaining, produce 1 vo- lume of ammoniacal gas; for this substance is formed of 3 volumes of hydrogen and 1 of azote, condensed into 2 volumes. See AM- MONIA. A given volume of cyanogen, then, com- CYA CYA bined first with an alkali, and then treated with an acid, produces exactly 1 volume of carbonic acid gas, 1 prussic acid vapour, 1 ammoniacal gas. It is very remarkable to see an experiment, apparently very complicated, give so simple a result. The metallic oxides do not seem capable of producing the same changes on cyanogen as the alkalis. Having precipitated proto-sul- phate of iron by an alkali, so that no free alkali remained, M. Gay Lussac caused the oxide of iron (mixed necessarily with much water) to absorb cyanogen, and then added muriatic acid. But he did not obtain the slightest trace of prussian blue ; though the same oxide, to which he had added a little potash before adding the acid, produced it in abundance. From this result one is induced to believe that oxide of iron does not combine with cyanogen ; and so much the more, because water impregnated with this gas never pro- duces prussian blue with solution of iron, un- less we begin by adding an alkali. See ACID (PRUSSIC). The peroxides of manganese and mercury, and the deutoxide of lead, ab- sorb cyanogen, but very slowly. If we add water, the combination is much more rapid. With the peroxide of mercury, we obtain a greyish-white compound, somewhat soluble in water. Cyanogen rapidly decomposes the carbon- ates at a dull red heat, and cyanides of the oxides are obtained. When passed through sulphuret of barytes, it combines without dis- engaging the sulphur, and renders it very fusible, and of a brownish-black colour. When put into water, we obtain a colourless solution, but which gives a deep brown (maroon) colour to muriate of iron. What does not dissolve contains a good deal of sulphate, which is doubtless formed during the preparation of the sulphuret of barytes. On dissolving cyanogen in the sulphuretted hydrosulphuret of barytes, sulphur is preci- pitated, which is again dissolved when the liquid is saturated with cyanogen, and we ob- tain a solution having a very deep brown ma- roon colour. This gas does not decompose sulphuret of silver, nor of potash. Cyanogen and sulphuretted hydrogen com- bine slowly with each other. A yellow sub- stance is obtained in tine needles, which dis- solves in water, does not precipitate nitrate of lead, produces no prussian blue, and is com- posed of ] volume cyanogen, and ! volume of sulphuretted hydrogen. Ammoniacal gas and cyanogen begin to act on each other whenever they come in contact ; but some hours are requisite to render the effect complete. We perceive at first a white thick vapour, which soon disappears. The diminution of volume is considerable, and the glass in which the mixture is made becomes opaque, its inside being covered with a solid brown matter. On mixing 90 parts of cya- nogen, and 227 ammonia, they combined nearly in the proportion of 1 to 1^-. This compound gives a dark orange-brown colour to water, but dissolves only in a very small proportion. The liquid produces no prussian blue with the salts of iron. When prussic acid is exposed to the action of a voltaic battery of 20 pairs of plates, much hydrogen gas is disengaged at the negative pole, while nothing appears at the positive pole. It is because there is evolved at that pole cyanogen, which remains dissolved in the acid. We may, in this manner, attempt the combination of metals with cyanogen, placing them at the positive pole. ' It is easy now to determine what takes place when an animal matter is calcined with potash or its carbonate. A cyanide of potash is formed. It has been proved, that by heat potash separates the hydrogen of the prussic or hydrocyanic acid. We cannot then suppose that this acid is formed, while a mixture of potash and animal matters is exposed to a high temperature. But we obtain a cyanide of potash, and not of potassium; for this last, when dissolved in water, gives only prussiate of potash (hydro-cyanate), which is decom- posed by the acids, without producing am- monia and carbonic acid ; while the cyanide of potash dissolves in water, without being altered, and does not give ammonia, carbonic acid, and prussic (hydrocyanic) acid vapour, unless an acid be added. This is the cha- racter which distinguishes a cyanide of a metal from a cyanide of a metallic oxide. See ACID (PRUSSIC). The preceding facts are taken from M. Gay Lussac's memoir on hydrocyanic acid, pre- sented to the Institute, September 18, 1815, and published in the Annales de Chimie, vol. xcv. In the Journal de Pharmacie for November, 1818, M. Vaiiquelin has publishedan elaborate dissertation on the same subject, of which I have given some extracts under ACID (PRUS- sic). I shall insert here his very elegant process for obtaining pure hydrocyanic or prussic acid, from the cyanide of mercury. Considering that mercury has a strong at- traction for sulphur, and that cyanogen unites easily to hydrogen, when presented in the proper state, he thought that sulphuretted hydrogen might be employed for decomposing dry cyanide of mercury. He operated in the following way: He made a current of sul- phuretted hydrogen gas, disengaged slowly from a mixture of sulphuret of iron, and very dilute sulphuric acid, pass slowly through a glass tube slightly heated, filled with the mercurial cyanide, and communicating with a receiver, cooled by a mixture of salt and snow. DAH 384 DAM As soon as the sulphuretted hydrogen came in contact with the mercurial salt, this last substance blackened, and this effect gradually extended to the farthest extremity of the ap - paratus. During this time no trace of sul- phuretted hydrogen could be perceived at the mouth of a tube proceeding from the receiver. As soon as the odour of this gas began to be perceived, the process was stopped; and the tube was heated in order to drive over the acid which might still remain in it The apparatus being unluted, he found in the receiver a co- lourless fluid, which possessed all the known properties of prussic acid. It amounted to nearly the fifth part of the cyanide of mercury employed. This process is easier, and furnishes more acid, than M. Gay Lussac's by means of muriatic acid. He repeated it several times, and always successfully. It is necessary merely to take care to stop the process before the odour of the sulphuretted hydrogen begins to be perceived, otherwise the hydrocyanic acid will be mixed with it However, we may avoid this inconvenience by placing a little carbonate of lead at the extremity of the tube. As absolute hydrocyanic acid is required only for chemical researches, and as it cannot be employed in medicine, it may be worth while, says M. Vauquelin, to bring to the recollection of apothecaries a process of M. Proust, which has, perhaps, escaped their attention. It consists in passing a current of sulphuretted hydrogen gas through a cold sa- turated solution of prussiate of mercury in water, till the liquid contains an excess of it ; to put the mixture into a bottle, in order to agitate it from time to time ; and finally, to filter it. If this prussic acid, as almost always hap- pens, contains traces of sulphuretted hydrogen, agitate it with a little carbonate of lead, and filter it again. By this process we may ob- tain hydrocyanic acid in a much greater de- gree of concentration than is necessary for medicine. It has the advantage over the dry prussic acid, of being capable of being pre- served a long time, always taking care to keep it as much as possible from the contact of air and heat. See ACID (PRUSSIC). In the first volume of the Journal of Science and the Arts, Sir H. Davy has stated some interesting particulars relative to cyanogen. By heating cyanide of mercury in muriatic acid gas, he obtained pure liquid prussic acid, and corrosive sublimate. By heating iodine, sulphur, and phosphorus, in contact with cya- nide of mercury, compounds of these bodies with cyanogen may be formed. That of iodine is a very curious body. It is volatile at a very moderate heat, and on coolirg col- lects hi flocculi, adhering together like oxide of zinc formed by combustion. It has a pun- gent smell, and very acrid taste. A portion of pure cyanide of mercury was heated till perfectly dry, and then inclosed in a green glass tube (see ACID CARBONIC), and being collected to one end, was decomposed by heat, whilst the other end was cooled. The cyanogen soon appeared as a liquid, limpid, colourless, and very fluid ; not altering its state at F. A tube containing it being opened in the air, the expansion within did not seem to be very great; and the liquid passed with comparative slowness into the state of vapour, producing great cold. The vapour collected over mercury proved to be pure cyanogen. Liquid cyanogen, evolved in contact with moisture, does not mix with the water, but floats over it. In a few days, the water and cyanogen react on each other, and carbonaceous matter is evolved. Mr. Faraday, Phil. Trans. 1 823. CYMOPHANE of Haiiy. The CHRY- SOBEBYL. CYSTIC OXIDE. See CALCULUS (URINARY). D DAHLINE. A vegetable principle dis- covered by M. Payen, analogous to starch and inulin. To extract it, the pulp of the bulbs of Dahlia is to be diffused in its weight of water, filtered through cloth, the liquid mixed with one-twentieth its weight of common chalk, boiled for half an hour, and filtered. The residuum of the bulbs is then to be pressed, the solutions united, and evaporated to three-fourths of their volume. Four per cent, of animal charcoal must now be added, and the whole clarified by the white of an egg. The liquor filtered and evaporated, until a film form on the surface, deposits dahlin on cooling. All the washings are to be treated in the same way, and thus 4 per cent, of dahline will be obtained from the bulbs. This substance when pure is white, ino- dorous, pulverulent, tasteless, sp. gr. 1.356, more soluble in hot than cold water, not soluble in alkohol, but precipitated by it from aqueous solutions. It differs from starch and inulin in forming a granulated mass when its aqueous solution is evaporated, as also in its specific gravity. M. Braconnot has discovered dahlin in the Jerusalem artichoke. He con- siders it merely as a variety of inulin. Annales de Chim. et Phys. xxiv. and xxv. DAMPS. The permanently elastic fluids which are extricated in mines, and are de- BAT 385 DEL structive to animal life, arc called clamps by the miners. The chief distinctions made by the miners are, choke-damp, which extin- guishes their candles, hovers about the bottom of the mine, and consists for the most part of carbonic acid gas; and fire-damp, or carbu- retted hydrogen, which occupies the superior spaces, and does great mischief by exploding whenever it comes in contact with their lights. See GAS, COMBUSTION, and LAMP. DAOURITE. A variety of red schorl from Siberia. DAPHNIN. The bitter principle of Daphne Alpina, discovered by M. Vauquelin. From the alcoholic infusion of this bark, the resin was separated by its concentration. On diluting the tincture with water, filtering, and adding acetate of lead, a yellow da-phnate of lead fell, from which sulphuretted hydrogen separated the lead, and left the daphnin in small transparent crystals. They are hard, of a greyish colour, a bitter taste when heated, evaporate in acrid acid vapours, sparingly soluble in cold, but moderately in boiling water. It is stated, that its solution is not precipitated by acetate of lead ; yet acetate of lead is employed in the first process to throw it down. DATOLITE. Datholit of Werner. This species is divided into two sub-species, viz. Common Datolite, and Botroidal Datolite. 1. Common Datolite. Colour white of various shades, and greenish-grey, inclining to celadine-green. It occurs in large coarse, and small granular distinct concretions, and crys- tallized. Primitive form, an oblique four- sided prism of 109 28', and 70 32'. The principal secondary forms are, the low oblique four-sided prism, and the rectangular four- sided prism, flatly acuminated on the extre- mities, with four planes which are set on the lateral planes. The crystals are small and in druses. Lustre shining and resinous. Cleav- age imperfect, parallel with the lateral planes of the prism. Fracture fine-grained, uneven, or imperfect conchoidal. Translucent or transparent. Fully as hard as apatite. Very brittle and difficultly frangible. Sp. gr. 2.9. When exposed to the flame of a candle it becomes opaque, and may then be rubbed down between the fingers. Before the blow- pipe it intumesces into a milk-white coloured mass, and then melts into a globule of a pale rose colour. Its constituents are, by Klaproth, silica 36.5, lime 35.5, boracic acid 24.0, water 4, trace of iron and manganese. It is asso- ciated with large foliated granular calcareous spar, at the mine of Nodebroe, near Arendal in Norway. It resembles prehnite, but is distinguished by resinous lustre, compact fracture, inferior hardness, and not becoming electric by heating. Jameson. 2. Botroidal Datolite. See BOTRYOHTE. DATURA. A supposed vegeto-alkali obtained from DATURA STRAMONIUM. DEAD-SEA WATER. See WATER. DECANTATION. The action of pour, ing off the clearer part of a fluid by gently inclining the vessel after the grosser parts have been suffered to subside. DECOCTION. The operation of boiling. This term is likewise used to denote the fluid itself, which has been made to take up certain soluble principles by boiling. Thus we say a decoction of the bark, or other parts of vegeta- bles, of flesh, &c. DECOMPOSITION is now understood to imply the separation of the component parts or principles of bodies from each other. The decomposition of bodies forms a very large part of chemical science. It seems pro- bable from the operations we are acquainted with, that it seldom takes place but in con- sequence of some combination or composition having been effected. It would be difficult to point out an instance of the separation of any of the principles of bodies which has been effected, unless in consequence of some new combination. The only exceptions seem to consist in those separations which are made by heat, and voltaic electricity. See ANALYSIS, GAS, METALS, ORES, SALTS, MINERAL WATERS. DECREPITATION. The crackling noise which several salts make when suddenly heated, accompanied by a violent exfoliation of their particles. This phenomenon has been ascribed to the " sudden conversion of the water which they contain into steam." But the very example, sulphate of barytes, to which these words are applied, is the strongest evi- dence of the falseness of the explanation ; for absolutely dry sulphate of barytes decrepitates furiously without any possible formation of steam, or any loss of weight. The same thing holds with regard to common salt, calcareous spars, and sulphate of potash, which contain no water. In fact, it is the salts which are anhydrous, or destitute of water, which decre- pitate most powerfully; those that contain water generally enter into tranquil liquefaction on being heated. Salts decrepitate, for the same reason that glass, quartz, and cast-iron crack, with an explosive force, when very suddenly heated ; namely, from the unequal expansion of the laminae which compose them, in conse- quence of their being imperfect conductors of heat The true cleavage of minerals may often be detected in this way, for they fly asunder at their natural fissures. DELPHINITE. See PISTACITE. DELPHINIA. A new vegetable alkali recently discovered by MM. Lasseigne and Feneulle, in the Delphinium staphysagria, or Stavesacre. It is thus obtained : The seeds, deprived of their husks, and ground, are to be boiled in a small quantity of distilled water, and then pressed in a cloth. The decoction is to be filtered, and boiled for a few minutes with pure magnesia. It must c c DEL 386 DEW then be re-filtered, and the residuum left on the filter is to be well washed, and then boiled with highly rectified alcohol, which dissolves out the alkali. By evaporation, a white pul- verulent substance, presenting a few crystalline points, is obtained. It may also be procured by the action of dilute sulphuric acid, on the bruised but un- shelled seeds. The solution of sulphate thus formed is precipitated by subcarbonate of potash. Alcohol separates from this precipitate the vegetable alkali in an impure state. Pure delphinia obtained by the first process is crystalline while wet, but becomes opaque on exposure to air. Its taste is bitter and acrid. When heated it melts ; and on cooling becomes hard and brittle like resin. If more highly heated, it blackens and is decomposed. Water dissolves a very small portion of it. Alcohol ar.d ether dissolve it very readily. The alco- holic solution renders syrup of violets green, and restores the blue tint of litmus reddened by an acid. It forms soluble neutral salts with acids. Alkalis precipitate the delphinia in a white gelatinous state, like alumina. Sulphate of delphinia evaporates in the air, . dues not crystallize, but becomes a transparent mass like gum. It dissolves in alcohol and water, and its solution has a bitter acrid taste. In the voltaic circuit it is decomposed, giving up its alkali at the negative pole. Nitrate of delphinia, when evaporated to dryness, is a yellow crystalline mass. If treated with excess of nitric acid, it becomes converted into a yellow matter, little soluble in water, but soluble in boiling alcohol. This solution is bitter, is not precipitated by potash, ammo- nia, or lime-water, and appears to contain no nitric acid, though itself is not alkaline. It is not destroyed by further quantities of acid, nor does it form oxalic acid. Strychnia and morphia take a red colour from nitric acid, but delphinia never does. The muriate is very soluble in water. The acetate of delphinia does not crystal- lize, but forms a hard transparent mass, bitter and acrid, and readily decomposed by cold sulphuric acid. The oxalate forms small white plates, resembling in taste the preceding salts. Delphinia, calcined with oxide of copper, gave no other gas than carbonic acid. It ex- ists in the seeds of the stavesacre, in combina- tion with malic acid, and associated with the following principles : 1. A brown bitter prin- ciple, precipitable by acetate of lead. 2. Vo- latile oil. 3. Fixed oil. 4. Albumen. 5. Ani- malized matter. 6. Mucus. 7. Saccharine mucus. 8. Yellow bitter principle, not preci- pitable by acetate of lead. 9. Mineral salts. Annales de Chimie ct de Physique, vol. xii. p. 358. DELIQUESCENCE. The spontaneous assumption of the fluid state by certain sa- line substances, when left exposed to the air, in consequence of th 441 swandown on the same, to 2 54f 58 ot 2 53 57 51 55- c, d, e. This illustrates the nature of saturation or definite proportions." " We can readily perceive from the fore- going demonstrations, that oxygen is retained with less force in the colourless nitrous acid than in the straw-coloured ; and the latter acid retains it with less force than the red nitrous acid ; and nitrous gas holds it with still more force than the red nitrous acid. This accounts for the separation of oxygen gas from the colourless nitrous acid (nitric acid) when exposed to the sun, at the same time that the acid becomes coloured. Nitrous acid in any other state will afford no oxygen when exposed to the sun." " Why the gaseous oxide should be more soluble in water than the nitrous gas is what I cannot account for, unless it be occasioned by the smaller size of its calorific atmospheres, which may admit its atoms to come within the gravitating influence of that fluid." It is impossible to deny the praise of inge- nuity to the above passages ; and every one must be struck with their analogy, both as to atomical doctrines and the calorific atmospheres of gases, single and' compound, with the lan- guage and views expanded at full length in Mr. Dalton's New System of Chemical Philo- sophy, first framed about the year 1803, and published in 1808. It appears that this philo- sopher, after meditating on the definite pro- portions in which oxygen was shown by M. Proust to exist in .he two oxides of the same metal, on the successive combinations of oxy- gen and azote, and the proportions of various other chemical compounds, was finally led to conclude, that the uniformity which obtains in corspucular combinations, results from the circumstance, that they consist of one atom of the one constituent, united generally with one atom of the other, or with two or three atoms. And he further inferred, that the relative weights of these ultimate atoms might be as- certained from the proportion of the two con- stituents in a neutral compound. Chemistry is unquestionably under the greatest obligations to Mr. Dalton, for the pains with which he collated the f arious ana- lyses of chemical bodies by different investiga- tors ; and for establishing, in opposition to the doctrine of indefinite affinity taught by Bar- thollet, that the different compounds of the same principles did not pass into each other by imperceptible gradations, but proceeded, per saltum, in successive proportions, each a multiple of the first. Mr. Dalton has thus been no mean contributor to the advancement of the science. It is difficult to say how far his figured groups of spherical atoms have been beneficial or not. They may have had some use in aiding the conception of learners, and perhaps in giving a novel and imposing air to the atomical fabric. But their arrangement, and even their existence, are altogether hypo- thetical, and therefore ought to have no place in physical demonstrations. That water is a compound of an atom of oxygen and an atom of hydrogen, is assumed by Mr. Dalton as the basis of his system. But two volumes of hydrogen here combine with one of oxygen. He therefore infers, that an atom of hydrogen occupies double the bulk, in its gaseous state, of an atom of oxygen. These assumptions are obviously gratuitous. 1 agree with Dr. Prout in thinking that Sir H. Davy has taken a more philosophical view of this subject. Guided by the strict logic of che- mistry, he places no hypothesis at the founda- tion of his fabric. Experiment shows, 1st, That in equal vo- lumes oxygen weighs 1C times more than hy- drogen ; and 2dly, That water is formed by the union of one volume of the former, and two volumes of the latter gas, or by weight of 8 to 1. We are not in the least authorized to infer from this, that an atom of oxygen weighs 8 times as much as an atom of hydrogen. For aught we know, water may be a compound of 2 atoms of hydrogen, and 1 of oxygen ; in which case we should have the proportion of the weights of the atoms, as given by equal vo- lumes, namely, 1 to 16. There is no good reason for fixing on one compound of hydrogen, more than on another, in the determination of the basis of the equivalent scale. If we deli- berate on that combination of hydrogen in which its agency is apparently most energetic, namely, that with chlorine, we would surely never think of pitching on two volumes as its unity or least proportion of combination ; for it is one volume of hydrogen which unites with one volume of chlorine, producing two volumes of muriatic gas. Here, therefore, we sse that one volume of hydrogen is quite adequate to effect, in an active gaseous body of equal bulk and 36 times its weight, an entire change of properties. Should we assume in gaseous che- mistry, 2 volumes of hydrogen as the combin- ing unit, or as representing an atom ; then it should never unite in 3 volumes, or an atom and a half with another gas. Ammonia, how- ever, is a compound of 3 volumes of hydrogen with 1 of azote; and if two volumes of hydro- gen to 1 of oxygen be called an atom to an atom, surely 3 volumes of hydrogen to I of azote should be called an atom and a half to an EQU 425 EQU atom. Yet the Daltonian Commentator, on the second occasion, counts one volume an atom of hydrogen, and on the first, two volumes an atom. We would steer clear of all these gratuitous assumptions and contradictions, by making a single volume of hydrogen represent its atom, or prime equivalent. " There is an advan- tage," says Dr. Prout, " in considering the volume of hydrogen equal to the atom, as, in this case, the specific gravities of most, or per- haps all elementary substances, (hydrogen be- ing one), will either exactly coincide with, or be some multiple of the weights of their atoms ; whereas, if we make the volume of oxygen unity, the weights of the atoms of most ele- mentary substances, except oxygen, will be double that of their specific gravities, with respect to hydrogen. The assumption of the volume of hydrogen being equal to the atom, will also enable us to find more readily the specific gravities of bodies in their gaseous state, (either with respect to hydrogen or at- mospheric air), by means of Dr. Wollaston's logometric scale. " If the views we have ventured to advance be correct, we may almost consider the TrpwTii uXij of the ancients to be realized in hydrogen : an opinion, by the by, not altogether new. If we actually consider this to be the case, and fur- ther consider the specific gravities of bodies, in their gaseous state, to represent the number of volumes condensed into one ; or in other words, the number of the absolute weight of a single volume of the first matter (?rpwT>5 uX^) which they contain, which is extremely probable ; multiples in weight must always indicate mul- tiples in volume, and vice versa ; and the spe- cific gravities or absolute weights of all bodies in a gaseous state, must be multiples of the specific gravity, or absolute weight, of the first matter, (Tipw-ry #Arj), because all bodies in a gaseous state, which unite with one another, unite with reference to their volume." From these ingenious observations, we per- ceive the felicity of judgment with which Sir H. Davy made choice of the single vo- lume of hydrogen, for the unit of primary combination, in his Elements of Chemical Philosophy. Mr. Dalton's prelections on the atomic theory, and even the first volume of his New System of Chemical Philosophy, excited no sensation in the chemical world adequate to their merits. That part of his system which treated on caloric was blended with so much mere hypothesis, that chemists transferred a portion of the scepticism thus created to his collation of primary and multiple combina- tions. It was Dr. Wollaston who first de- cided public opinion in favour of the doctrine of multiple proportions, by his elegant paper on super-acid and sub-acid salts, inserted in the Philosophical Transactions for 1008. The object of the atomic theory has been no where so happily stated as by this philosopher, in the following sentence : " But, since the publication of Mr. Dal- ton's theory of chemical combination, as ex- plained and illustrated by Dr. Thomson, (System, 3d edit.) the inquiry which I had designed appears superfluous, as all the facts I had observed are but particular instances of the more general observation of Mr. Dalton, that in all cases the simple elements of bodies are disposed to unite atom to atom singly, or if either is in excess, it exceeds by a ratio to be expressed by some simple multiple of the number of its atoms." It is evident from this passage, that the principle which presented itself to Mr. Dalton, on a review of the labours of other chemists, had really occurred to Dr. Wollaston from his own, and that he would unquestionably have been speedily led to its full develop- ment. Dr. Wollaston, in the above decisive paper, demonstrates, that in the sub-carbonate and crystallized carbonate of potash, the relation of the carbonic acid to the base, in the first, is exactly one-half of what it is in the second. The same law is shown to hold with regard to the two carbonates of soda, and the two sulphates of potash ; and being applied to his experiments on the compounds of potash and oxalic acid, leads him to conclude that the neutral oxalate may be considered as consist- ing of 2 particles of potash to 1 acid ; the binox- olate as 1 and 1, or 2 potash with 2 acid ; the quadroxalate as 1 and 2, or 2 potash with 4 acid. We cannot withhold from our readers the following masterly observations, which must make every one regret that the full develop- ment of the atomic theory had not fallen within the scope of his researches. " But an explanation which admits a dou- ble share of potash in the neutral salts (the oxalates), is not altogether satisfactory ; and I am farther inclined to think that, when our views are sufficiently extended to enable us to reason with precision concerning the propor- tions of elementary atoms, we shall find the arithmetical relation alone will not be sufficient to explain their mutual action, and that we shall be obliged to acquire a geometrical con- ception of their relative arrangement, in all the three dimensions of solid extension. " For instance, suppose the limit to the approach of particles to be the same in all directions, and hence their virtual extent to be spherical (which is the most simple hypothe- sis) ; in this case, when different sorts com- bine singly, there is but one mode of union. If they unite in the proportion of two to one, the two particles will naturally arrange them- selves at opposite poles of that to which they unite. If they be three, they might be ar- EQU 426 EQU ranged with regularity at the angles of an equilateral triangle, in a great circle surround- ing the single spherule ; but in this arrange- ment, for want of similar matter at the poles of this circle, the equilibrium would be un- ^ stable, and would be liable to be deranged by the slightest force of adjacent combinations; but when the number of one set of particles exceeds in the proportion of 4 to 1, then, on the contrary, a stable equilibrium may again take place, if the four particles are situated at the angles of the four equilateral triangles composing a regular tetrahedron. 4< But as this geometrical arrangement of the primary elements of matter is altogether conjectural, and must rely for its confirmation or rejection upon future inquiry, I am desi- rous that it should not be confounded with the results of the facts and observations related above, which are sufficiently distinct and sa- tisfactory with respect to the existence of the law of simple multiples. It is perhaps too much to hope, that the geometrical arrange- ment of primary particles will ever be perfectly known ; since, even admitting that a very small number of these atoms combining together, would have a tendency to arrange themselves in the manner I have imagined ; yet, until it is ascertained how small a proportion the pri- mary particles themselves bear to the interval between them, it may be supposed that sur- rounding combinations, although themselves analogous, might disturb this arrangement; and in that case, the effect of such interference must also be taken into the account, before any theory of chemical combination can be rendered complete." I am not aware that any chemist has adduced experimental evidence, to prove that a " stable equilibrium may again take place, if the four particles are situated at the angles of the four equilateral triangles composing a regular tetra- hedron." I have, therefore, much pleasure in referring to my researches on the constitution of liquid nitric acid, as unfolding a striking con- firmation of Dr. Wollaston's true philosophy of atomical combination. When I wrote the following sentence, I had no recollection what- ever of Dr. Wollaston's profound speculations on tetrahedral arrangement " We perceive, that the liquid acid of 1.420, composed of 4 primes of water + 1 of dry acid, possesses the greatest power of resisting the influence of tem- perature to change its state. It requires the maximum heat to boil it, when it distils unchanged ; and the maximum cold to effect its congelation." See ACID (NiTRic), in this Dictionary. Here we have a fine example of the stabi- lity of equilibrium, introduced by the combina- tion of four atoms with one. The discovery which I had also the good fortune to make with regard to the constitution of aqueous sul- phuric acid, that the maximum condensation occurred when cne atom of the real acid wc combined with three atoms of water, is equal- ly consonant to Dr. Wollaston's views. " But in this arrangement," says Dr. Wollaston, u for want of similar matter at the poles of this circle, the equilibrium would be unstable and would be liable to be deranged by the slightest force of adjacent combinations." Compare with this remark, the following sen- tence from my paper on sulphuric acid, as pub- lished in the Journal of Science, Oct. 1817. " The terms of dilution are, like logarithms, a series of numbers in arithmetical progression, corresponding to another series, namely, the specific gravities, in geometrical progression. For a little distance on both sides of the point of greatest condensation, the series converges with accelerated velocity, whence the 10 or 12 terms on either hand deviate a little from ex- periment." Page 126. Or in other words, a small addition of water or of acid to the above atomic group, produces a, great change on the degree of condensation; which accords with the position " that the equilibrium would be liable to be deranged by the slightest force of adjacent combinations." While considering this part of Dr. Wollas- ton's important paper, let me advert to the curious facts pointed out in the article NITRIC ACID, relative to the compound of one atom of dry acid and seven atoms water. In my paper on the subject, published in the eighth number of the Journal of Science, I showed that this liquid combination was accompanied with the greatest condensation of volume, and the greatest disengagement of heat. In com- posing this Dictionary, I calculated, for the first time, the atomical constitution of the nitric acids employed by Mr. Cavendish for congelation ; and found with great satisfac- tion, that the same proportion which had ex- hibited, in my experiments, the most intense reciprocal action, as was indicated both by the aggregation of particles and production of heat, was likewise that which most favoured solidification. Such acid congeals at 2; but when either stronger or weaker, it requires a much lower temperature for that effect. 3. The next capital discovery in multiple proportions was made by M. Gay Lussac, in 1808, and published by him in the second volume of the Memoircs (CArcueil. After detailing a series of fine experiments, he de- duces the following important inferences : " Thus it evidently appears, that all gases, in their mutual action, uniformly combine in the most simple proportions; and we have seen, in fact, in all the preceding examples, that the ratio of their union is that of 1 to 1, of 1 to 2, or of 1 Co 3, by volume. It is im- portant to observe, that when we consider the weights, there is no simple and definite relation between the elements of a first combination; it is only when there is a second between these EQU 427 EQU same elements, that the new proportion of that body|which has been added is a multiple of the first. Gases, on the contrary, in such proportions as can combine, give rise always to compounds, whose elements are in volume, multiples the one of the other. " Not only do the gases combine in very simple proportions, as we have just seen, but moreover, the apparent contraction of volume which they experience by combination, has likewise a simple relation with the volume of the gases, or rather with the volume of one of them." By supposing the contraction of volume of the two gaseous constituents of water to be only equal to the whole volume of oxygen added, he found the ratio of the density of steam to be to that of air as 10 to 16 ; a com- puted result in exact correspondence with the experimental result lately obtained in an independent method by the same excellent philosopher. " Ammoniacal gas is composed in volume," says he, " of 3 parts of hydrogen and 1 of azote, and its density, compared to that of air, is 0.596 ; but if we suppose the apparent contraction to be one-half of the total volume, we find 0.594 for its density. Thus it is demonstrated by this nearly perfect accordance, that the apparent contraction of its elements is precisely one-half of the total volume, or rather double the volume of azote." M. Gay Lussac subjoins to his beautiful me- moir a table of gaseous combination, which, with some modifications derived from subse- quent researches, will be inserted under the article GAS. The same volume of the Memoires presents another important discovery of M. Gay Lus- sac, on the subject of equivalent proportions. It is entitled, On the relation which exists between the oxidation of metals, and their capacity of saturation for the acids. He here proves, by a series of experiments, that the quantity of acid which the different metallic oxides require for saturation, is in the direct ratio of the quantity of oxygen which they respectively contain. " I have arrived at this principle," says he, " not by the comparison of the known proportions of the metallic salts, which are in general too inexact to enable us to recognize this law, but by observing the mutual precipitation of the metals from their solutions in acids." When we precipitate a solution of acetate of lead by a plate of zinc, there is formed a beautiful vegetation known under the name of the tree of Saturn ; and which arises from the reduction of the lead by a galvanic process, as was first shown by Silvester and Grotthus. We obtain at the same time a solution of acetate of zinc, equally neutral with that of the lead, and entirely exempt from this last metal. No hydrogen, or almost none, is disengaged during the precipitation ; which proves, that the whole oxygen necessary to the zinc, for its becoming dissolved and saturating the acid, has been furnished to it by the lead. If we put into a solution of sulphate of copper, slightly acidulous, bright iron turnings in excess, the copper is almost instantly pre- cipitated; the temperature rises, and no gas is disengaged. The sulphate of iron which we obtain, is that in which the oxide is at a minimum, and its acidity is exactly the same as that of the sulphate of copper employed. We obtain similar results by decomposing the acetate of copper by lead, especially with the aid of heat. But since the zinc precipi- tates the lead from its acetic solution, we may conclude, that it would also precipitate copper from its combination with the acetic acid. Experience is here in perfect accordance with theory. We know with what facility copper preci- pitates silver from its nitric solution. All the oxygen which it needs for its solution is furnished to it by the oxide of silver ; for no gas is disengaged, and the acidity is unchanged. The same thing happens with copper in regard to nitrate of mercury, and to cobalt in regard to nitrate of silver. In these last examples, as in the preceding, the precipitating metal finds, in the oxide of the metal which it precipitates, all the oxygen which is necessary to it for its oxidizement, and for neutralizing to the same degree the acid of the solution. These incontestable facts naturally conduct to the principle announced above, that the acid in the metallic salts is directly proportional to the oxygen in their oxides. In the precipita- tion of one metal by another, the quantity of oxygen in each oxide remains the same, and consequently the larger dose of oxygen the precipitating metal takes, the less metal will it precipitate. M. Gay Lussac next proceeds to show, with regard to the same metals at their different stages of oxidizement, that they require of acid a quantity precisely proportional to the quantity of oxygen they may contain ; or that the acid in the salts is exactly proportional to the oxygen of the oxides. A very important result of this law is, the ready means it affords of determining the proportions of all the me- tallic salts. The proportions of one metallic salt, and the oxidation of the metals being given, we may determine those of all the salts of the same genus ; or the proportions of acid, and of oxide, of all the metallic salts, and the oxidation of a single metal being given, we can calculate the oxidation of all the rest Since the peroxides require most acid, we can easily understand how the salts containing them should be in general more soluble than those with the protoxide. M. Gay Lussac concludes his memoir with this observation. When we precipitate a me- tallic solution, by sulphuretted hydrogen, either alone or combined with an alkaline base, we obtain a sulphurct or a metallic hydrosul- EQU 428 EQU phuret. In the first case, the hydrogen of the sulphuretted hydrogen combines with all the oxygen of the oxide, and the sulphur forms a sulphuret with the metal : in the second case, the sulphuretted hydrogen combines directly with the oxide, without being decomposed ; and its proportion is such that there is sufficient hydrogen to saturate all the oxygen of the oxide. The quantity of hydrogen neutralized, or capable of being so, depends therefore on the oxidation of the metal, as well as the quantity of the sulphur which can combine with it. Of consequence, the same metal forms as many distinct sulphurets, as it is susceptible of distinct stages of oxidation in its acid solu- tions. And as these degrees of oxidation are fixed, we may also obtain sulphurets, of definite proportions, which we can easily determine, according to the quantity of oxygen to each metal, and the proportions of sulphuretted . hydrogen. The next chemist who contributed essen- tially to the improvement of the equivalent ratios of chemical bodies, was Berzelius. By an astonishing number of analyses, executed for the most part with remarkable precision, he enabled chemical philosophers to fix, with corresponding accuracy, the equivalent ratios reduced to their lowest terms. He himself took oxygen as the unit of proportion. The results of all this emulous cultivation were combined, and illustrated with original researches, by Sir H. Davy, in his Elements of Chemical Philosophy, published in 1812. What peculiarly characterizes this chemical work, is the sound antihypothetical doctrines which it inculcates on chemical combination. u Mr. Higgins," says Sir H. " has supposed that water is composed of one particle of oxy- gen and one of hydrogen, and Mr. Dalton of an atom of each ; but in the doctrine of propor- tions derived from facts, it is not necessary to consider the combining bodies, either as com- posed of indivisible particles, or^even as always united, one and one, or one and two, or one and three proportions. Cases will be hereafter pointed out, in which the ratios are very dif- ferent ; and at present, as we have no means 'whatever of judging either of the relative numbers, figures, or weights, of those parti- cles of bodies which are not in contact, our numerical expressions ought to relate only to the rnsults of experiments." He conceives that the calculations will be much expedited, and the formulae rendered more simple, by considering the smallest pro- portion of any combining body, namely, that of hydrogen, as the integer. This radical proportion of hydrogen, is the TT^WTTJ v\r, of the ancient philosophers. It has been objected by some, to our as- suming hydrogen as the unit, that the num- bers representing the vnetals would become inconveniently large. But this could never bo urged by any person acquainted with the theory of numbers. For in what respect is it more convenient to reckon barium 8-75 on the atomic scale, or 8-75 X 16 =140 on Sir H. Davy's scale of experiment ; or is it any advantage to name, with Dr. Thomson, tin 7-375, or to call it 118, on the plan of the English philosopher ? If the combining ratios of all bodies be multiples of hydrogen, as is probable, why not take hydrogen as the unit ? I think this question will not be answered in the negative, by those who practise the reduc- tion of chemical proportions. The defenders of the Daltonian hypothesis, that water consists of one atom oxygen to one atom hydrogen, may refer to Dr. Wollaston's scale, as authority for taking oxygen as the unit But that ad- mirable instrument, which has at once subjected thousands of chemical combinations to all the dispatch and precision of logonietric calcula- tion, is actually better adapted to the hydrogen unit than to the oxygen. For if we slide ilown the middle rule, till 10 on it stand opposite to 10 hydrogen on the left side, every thing on the scale is given in accordance with Sir H. Davy's system of primary proportions, and M. Gay Lussac's theory of gaseous combina- tion. This valuable concurrence, as is well pointed out by Dr. Prout, we lose, by adopting the volume of oxygen as radix. In the first part of the Phil. Trans, for 1814, appeared Dr. Wollaston's description of his scale of chemical equivalents. an instru- ment which has contributed more to facilitate the general study and practice of chemistry than any other invention of man. His paper is further valuable, in presenting a scries of numbers denoting the relative primary propor- tions, or weights of the atoms of the principal chemical bodies, both simple and compound, determined with singular sagacity, from a general review of the most exact analyses of other chemists, as well as his own. The list of substances which he has esti- mated, are arranged on one or other side of a scale of numbers, in the order of their relative weights, and at such distances from each other, according to their weights, that the series of numbers placed on a sliding scale can at plea- sure be moved, so that any number expressing the weight of a compound, may be brought to correspond with the place of that compound in the adjacent column. The arrangement is then such, that the weight of any in- gredient in its composition, of any reagent to be employed, or precipitate that might be obtained in its analysis, will be found op- posite the point at which its respective name is placed. If the slider be drawn upwards, till 100 corresponds to muriate of soda, the scale will then show how much of each substance con- tained in the table is equivalent to 100 of common salt. It shows, with regard to the different views of this salt, that'it contains 46.6 dry muriatic acid, and 53,4 of soda, or EQU 429 EQU 39.8 sodium, and 13.6 oxygen ; or if viewed as chloride of sodium, that it contains 60.2 chlorine, and 39.8 sodium. With respect to reagents, it may be seen, that 283 nitrate of lead, containing 191 of litharge, employed to separate the muriatic acid, would yield a precipitate of 237 muriate of lead, and that there would then remain in solution nearly 146 nitrate of soda. It may at the same time be seen, that the acid in this quantity of salt would serve to make 232 corrosive sublimate, containing 185.5 red oxide of mercury; or make 91.5 muriate of ammonia, composed of 62 muriatic gas (or hydromuriatic acid), and 29.5 ammonia. The scale shows also, that for the purpose of obtaining the whole of the acid in distillation, the quantity of oil of vitriol required is nearly 84, and that the residuum of this distillation would be 122 dry sulphate of soda, from which might be obtained, by crystallization, 277 of Glauber salt, con- taining 155 water of crystallization. These, and many more such answers, appear at once, by bare inspection, as soon as the weight of any substance intended for examination is made, by motion of the slider, correctly to cor- respond with its place in the adjacent column. Now, surely, the accurate and immediate solu- tion of so many important practical problems, is an incalculable benefit conferred on the chemist. With regard to the method of laying down the divisions of this scale, those who are ac- customed to the use of other sliding rules, and are practically acquainted with their properties, will recognize upon the slider itself, the com- mon Gunter's line of numbers (as it is called), and will be satisfied, that the results which it gives are the same that would be obtained by arithmetical computation. Those who are acquainted with the doctrine of ratios, and with the use of logarithms as measures of ratios, will understand the prin- ciple on which this scale is founded, and will not need to be told, that all the divisions are logometric ; consequently, that the mechanical addition and subtraction of ratios here per- formed by juxtaposition, correspond in effect to the multiplication and division of the numbers, by which those ratios are expressed in common arithmetical notation. In his Essay on the Cause of Chemical Pro- portions, Berzelius proposed a system of signs, to denote atomical combinations, which it may be proper briefly to explain. This sign is the initial letter, and by itself always expresses one atom, volume, or prime of the substance. When it is necessary to indicate several volumes or primes, it is done by prefixing the number; for example, the cuprous oxide, or protoxide of copper, is composed of a prime of oxygen and a prime of metal; its sign is therefore CM -f O. The cupric oxide, or deutoxide of copper, is composed of 1 prime metal, and 2 primes oxygen ; therefore its sign is Cit +2O. In like manner the sign for sulphuric acid is S -f- 3 O ; for carbonic acid, C + 2 O ; for water, 2 H -f- O, Ac. When we express a compound prime of the first order, or binary, we throw away the +, and place the number of primes above the letter, as the index or exponent is placed in arithmetic. For example, Cu O -f- SO3 sulphate of copper; CuO 2 + 2SO3 = bi- deutosulphate of copper, or persulphate. These formulae have this advantage, that if we take away the oxygen, we see at once the ratio between the radicals. As to the primes of the second order, or ternary compounds, it is but rarely of any advantage to express them by formulas, as one prime ; but if we wish to express them in that way, we may do it by using the parenthesis, as is done in algebraic formulas : for example, according to Berzelius, alum is composed of 3 primes of sulphate of alumina, and 1 of sulphate of potash. Its symbol is 3 (Al + 2SC-3) -f- (Po* + 2SO3). The prime of ammonia is 3HN; viz. 3 primes hydrogen -f- 1 nitrogen. We shall use some of these abbreviations in our table of equivalent primes, at the article SALT. To reduce analytical ' results, as usually given for 100 parts, to the equivalent prime ratios, or, in hypothetical language, to the atomic proportions, is now a problem of per- petual recurrence, with which students are perplexed, as no rule has been given for its ready solution. Though numerous examples of its solution occur in this Dictionary, we shall here explain it in detail. As in all reasoning we must proceed from what is known or determinate, to what is unknown or indeterminate, so, in every ana- lysis, there must be one ingredient whose prime equivalent is well ascertained. This is employed as the common measure, and the proportions of the rest are compared to it. Let us take, for instance, Sir H. Davy's analysis of flu ate of lime, to determine the unknown number that should denote the prime of fluoric -acid. We know, first of all, that two primes of oxygen = 2, combine with 1 of carbon = 0.75, to form the compound prime 2.75 of carbonic acid. We likewise know that carbo- nate of lime consists of 44 carbonic acid -}- 56 lime. We therefore make this proportion to determine the prime equivalent of lime. 1. 44 : 56 : : 2 75 : 3.5 = prime of lime. 2. We know that 100 parts of dry sulphate of lime, consist of 41.2 lime and 58.8 acid. Hence, to find the prime of sulphuric acid, we make this proportion : 41.2 : 58.8 : : 3.5 : 5 = prime of sulphuric acid. 3. Sir H. Davy obtained from 100 grains of fluor spar in powder, acted on with repeated quantities of sulphuric acid, and ignited, 1 75.2 grains of sulphate of lime. Now, since EQU 430 EQU 100 grains of sulphate of lime contain, as above, 41.2 of lime, we have this proportion : 100 : 41.2 : ; 175-2 : 72.18 = lime, cor- responding to 175-2 grains of sulphate, and which previously existed in the 100 gr. of fluor spar. If from 100 we subtract 72.18, the difference 27-82 is the fluoric acid, or the other ingredient of the fluor, which saturated the lime. Now to find its prime equivalent, we say, 72.18 : 3.560 : : 27-82 : 1 -349 = the prime or atom of fluoric acid from Sir H. Davy's experiment ; or in round numbers = 1.35. We shall give another example, derived from a more complex subject. M. Vauquelin found, that 33 parts of lime, saturated with sorbic acid, and carefully dried, weighed 100 grains. Hence the difference, 67 grains, was acid, To find its equivalent prime, we say, As 33 : 67 : : 3.5 = the prime of lime : 7.1 the prime of the acid. But as he brought it to absolute neutrality by a small portion of potash, we may take 7.5 for the prime. M. Vauquelin subjected the acid, as it exists in the dry sorbates of lead and copper, to igneous analysis ; and obtained the following results : Hydrogen, 16.8 Carbon, 28.3 Oxygen, 54.9 100.0 Now we must find such an assemblage of the primes or atoms of these elements, as will form a sum-total of 7-5; and at the same time be to each other in the above proportions. The following very simple rule will give a ready approximation ; and with a common sliding scale it may be worked by inspection. Multiply each proportion per cent, by the compound prime, and compare the products with the multiples of the constituent primes. You can then estimate the number of each prime requisite to compose the whole. Thus, Theory. Experiment. 0.168 X 7-5 r= 1.2600 or 10 hydrogen = 1.25 16.7 16.8 0.283 X 7-5 = 2.1225 3 carbon = 2.25 0.549 X 7.5 = 4.1175 4 oxygen = 4.00 7.50 30.0 53.3 28.3 54-9 100.0 100.0 The differences between these theoretical and experimental proportions, are probably within the limits of the errors of the latter, in the present state of analysis. If, on Dr. Wollaston's scale, we mark with a type or a pen, 2h, 3h, &c. up to lOh ; 2c, 3c, 4c, 5c; and 2n, 3n, 4n; respectively opposite to twice, thrice, &c. the atoms of hydrogen, carbon, and nitrogen, as is already done for oxygen, (with the exception of the fourth, where copper stands), we shall then have ready approximations to the prime com- ponents, by inspection of the scale. Move the sliding part, so that one of the quantities per cent, may stand opposite the nearest estimate of a multiple prime of that constituent. Thus we know that hydrogen, carbon, and oxygen, bear the relation to each other of 1, 6, 8 ; and, of course, the latter two, that of 3 to 4. But 54.9 oxygen, being more than one-half of 100, the weight of oxygen in the compound prime is more than the half of 7-5, and therefore points to 4. Place 54.9 opposite 4 oxygen, (where copper stands), we shall find 18 oppo- site 10 hydrogen, and 30-7 opposite 3 carbon. Here we see the proportions of carbon and hydrogen are both greater than by Vauquelin's analysis. Try 51 opposite 4 oxygen, then opposite 3 carbon we have 28-7, and opposite 10 hydrogen 16.9. The proportions I have calculated arithmetically above, seem some- what better approximations; they were deduced from hydrogen 0.1 25, and carbon 0.75, instead of 0.132 and 0.754, as on the scale. If the weight of the compound prime is not given, then we must proceed to estimate the nearest prime proportions, after inspection of those per cent. The scale may be used with advantage, as just now explained, The following case has been reckoned dif- ficult of solution, and has been even involved in an algebraic formula. Let us suppose a vegetable acid, containing combined water, whose prime equivalent is to be determined by experiment. A crystallized salt is made with U, for example, and a determinate qua/i- tity of soda. Suppose the alkali to form 26 per cent of the salt. The rest is water and acid. Dissolve 100 grains, and add them to an indefinite quantity of the solution of any salt, with whose base the vegetable acid forms an insoluble compound. Dry and weigh this precipitate. Without decomposing the latter, we have sufficient data far determining the prime equivalent of the real acid. We make this proportion : As the weight of soda is to its prime equivalent, so is the weight of the precipitate to the prime of the compound. Suppose 148 grains of an insoluble salt of lead to have been obtained ; then 26 : 3.95 : : 148 : 22.1 = the prime of the salt of lead. From this, if we deduct the weight of the prime equivalent of oxide of lead = 14, we have 8.1 for the prime equivalent of the acid. EQU 431 EQU And the crystallized salt must have consisted of, Dry acid, 53.3 Soda, 26.0 Water, 20.7 100.0 As the above numbers were assumed merely for arithmetical illustration, the water is not atomically expressed. Indeed the problem of finding the acid prime, does not require the salt to be either dried or weighed. A solution would suffice. Saturate a known weight of alkali with an unknown quantity of the crys- tallized acid. Add this neutral solution to a redundant quantity of solution of nitrate of lead. Wash, dry, and weigh the insoluble precipitate, and apply the above rule. There are three systems of equivalent numbers at present employed : 1st, That having oxygen as the radix ; 2d, That having one volume of hydrogen as the radix; 3d, That having two volumes of hydrogen as the radix, on the Daltonian supposition, that two volumes of hydrogen contain the same number of atoms as one volume of oxygen. Since the volume of hydrogen is equal in weight to l-l6th the weight of the volume of oxygen, the former two systems are mutually converti- ble, by multiplying the number in the oxygen ratio by 16, or 4 X 4, to obtain the number in the hydrogen scale ; and this is reconverted by the inverse operation, namely, dividing by 16, or by 4 X 4. Dr. Wollaston's scale, and Sir H. Davy's proportional numbers, are adapted to the idea that water is a compound of 1 hydrogen + 7-5 oxygen by weight, or 15 -f- 1 by volume. Their mutual conversion is therefore very easy ; for if we add to Dr. Wollaston's num- ber its half, the sum is Sir H. Davy's ; and of course, if we subtract from the number of the latter its third, the remainder is Dr. Wollas- ton's number. .There is one very frequent variation in the weights of the primes among the best writers, namely, doubling or halving the number. This difference i& occasioned generally by an uncertainty about the first term or proportion in which the body com- bines with oxygen ; some chemists reckoning that a protoxide which others consider a deut- oxide. Thus Sir H. Davy gives 103 as the number representing iron ; from which, if we deduct %Z = 34.3, the remainder 68.7 is nearly double of 34.5, the number of Dr. Wollaston. I shall insert here a table of prime equiva- lents. The first column of numbers corre- sponds, in general, to the determinations of the chemists of this country, hydrogen being reckoned unity ; the second column of num- bers, as also the literal symbols, belong to Berzelius, who takes for his radix, oxygen ;= 100. Annals of PW. N. S. vii. 185, and ix. 439. TABLE OF CHEMICAL EQUIVALENTS. Substances. Hydrogen = 1. Oxygen = 100. Symbols. Acid, acetic i 50 64M2 A~ crystallized (1 water) 59 . 62 1440-77 A* arscnious 54 J. *<*!/ / f 1240-77 XL9 As benzoic 120 1509-55 ~B~ boracic ? .... 22 26965 B crystallized (2 water) 40 22 ,275.33 c chloric 76 942-65 'M~ chloriodic -^ 161 chlorocarbonic !pfcfr4 58 chlorocyanic ".. . -.. * 62 V CO 1 O/\O * 4 J"M - citric OJ, fifi loUo-o4 '797.fl.ei Cn c EQU 432 EQU Substances. Hydrogen = 1. Oxygen = HM). Symbols. Acid, citric, crystallized (2 water) - 76 columbic ? '" ' '" .^ - r ' 152 192315 Ta ferrocyanic ;; -^ 0^4 ..' - . p fluoboric ? 22 544-68 FB fluoric . '"' 17 ^7 275-03 463-93 F F~ fluosilicic "."-*'" .. ' gallic' ^ $ 24 <;q 2017-93 701 78 JT Fa Si ~( hydriodic Y> . . DO 126 /.M-/0 hydrocyanic .... 27 hydrofluoric 17 hydrosulphurous 24 hyposulphuric .... 36 iodic : .'.'' .-'',> 165 2066-70 "l' malic ."; -'j-j/.r' ; ' , 70 molybdic ,'.'',. 72 896-80 Mo molybdous " .-.';[ *-; 64 796-80 Mo muriatic . ; , . 37 342-65 M nitric (dry) 54 677-26 N liquid, sp. gr. 1.485, (2 water) 72 nitrous 7 -- ; -.- , 46 36 477-26 2710-6 isr o crystallized (4 water) ' 72 perchloric 92 1142-65 : M" phosphoric . . 28 89230 'p phosphorous 20 1{\K 692-30 p' succinic (anhydrous crystals) 1UD 50 627-85 "s sulphuric (dry) liquid, sp. gr. 1.4838 40| 49 J 501-16 's' sulphurous ^" 32 401-16 8 tartaric . . . crystallized (1 water) 671 76 / 834-49 ~T tungstic . uric V ' r". ' 120) 45? J 1507-69 W Alum (dry) * '* 262 crystallised (25 water) 487 EQU EQU Substances. H ydrogen Oxygen = 100. Symbols. Alumina ... 27 642-33 Xi sulphate 67 2145-80 A1S3 subsulphate (2 acid 3 base) 116 Aluminum '. ! 19 342-33 Al Ammonia . . . , v . 17 214-67 NH6 acetate .-..' 67 856-56 NH6A bicarbonate (2 water) 79 766-10 NH6C* borate ? (dry) \. 39 485-09 NHB crystallized (2 water) 57 carbonate . > '.:. 39 490-77 NHC sesquicarbonate (2 water) 118 citrate '.... '. 75 943-33 NH 6 C fluoborate . . i>; . 39 hydriodate 143 109 OOPO 14 NH I molybdate '+' muriate - - lOA 89 54 71 .^<>_j' 14 1112-24 558-09 001. OQ NH Mo NHM TVH6 M oxalate : ' : ' ') / l 53 OtJ 1 OO 667-21 1>I tV IN NH6Q (crystallized, 1 water) 62 phosphate .... 45 1321-44 2 NH6-f P phosphite 37 1121-44 2NH+P succinate .... 67 842-42 NHS sulphate ',".- 57 715-73 NH's' sulphite . 49 615-73 NHS tartrate .,-' 84 1049-06 NHT potassa- tartrate .... 208 Antimony ... 44 o/\ 1612-90 Sb c'u TV!-* iodide oO 1C9 2940-85 6313-0 OD 1V1 3 Sb 13 deutoxide r >*" * 56 2012-90 Sb" peroxide - ~ .;. > 60 2112-90 'Sb protoxide 52 1912-90 Sb sulphuret 60 2216-38 SbS3 potassa- tartrate * ^ ' ? Arseniate of ammonia potash 70 110 1871-65 2620-60 2 NHAs KAs EQU EQU Substances. Hydrogen s=s 1. Oxygen = 100. Symbols. Arseniate of soda .... 94 2222-61 NaAs Arsenic [ ';.. . ' . 38 62 940-77 As iodide : .' :v/ --l : ;. '-'. ? Arsenious acid '". ' . . 54 Azote '* l '^ if .. .'.. vv. 14 70 177-26 1713-86 N Ba chloride f V 106 195 2599-16 4847-26 BaM* ]Ba I 2 *iO i */ O phosphuret .... 82 2106-16 BaP? sulphuret 86 Barytes 78 1913-86 3196-1 Ba Ba A 2 140 Ba As Iriv benzoate 198 inn 4932-96 H 7 1UU inn 24o3-17 .. .. chlorate 1UU 154 3799-16 S chromate . . . 130 3217-50 BaCh citrate 136 3369-56 BaC 2 hydrate 87 2138-73 Ba+2Aq q/iq fin IT or* Ra Ta nitrate ;*'- . 132 3268-38 x>a i JBa N 2 muriate (crystallized, 1 water) . 124 3048-90 5aM 2 -|-4A( oxalate 114 2817-40 J5aO phosphate , : , ^ . 106 2806-16 Ba'P phosphite 98 2606-16 Ba'p succinate 128 3169-56 BaS 2 sulphate 118 2916-18 BaS 2 sulphite 110 1 4 f 2716-18 "O ''*> tungstate ... 145 198 3582-84 4929-24 I5a I 2 Ba W 2 Benzoic acid ... 120 1509-55 B Bicarburetted hydrogen . '. ' 7 88-60 HC EQU 435 EQU Substances. Hydrogen = *. Oxygen = 100. Symbols. Bismuth ' ' vi* _ .^ r . j, 72 1773-8 Bi acetate ' - 130 325G-0 BiA* arseniate ' - * - - ' 142 3414-57 BiAs benzoate 200 4992-90 BiB chloride 108 2659-10 BiM* citrate 138 3429-5 Bi(> iodate . 245 6107-2 Bil . ... 197 4907-2 Bi I* nitrate 134 3328-32 BiN oxalate ' * ; ' 116 2877-34 BiO 2 oxide " ' '"- - ,7 80 1973-80 Bi phosphate 107 2866-10 Bi P phosphuret 84 sulphate 120 2976-12 BiS* sulphuret 88 2176-12 BiS - tartrate > ' 147 3642-78 BiT Boracic acid ' 22? 269-65 B acid crystallized (2 water) 40 Borax (8 water) .... 158 Boron 6? 69-655 B Cadmium 56 1393-54 Cd carbonate 86 2144-20 C d C chloride 92 2278-84 Cd M* iodide ..... 181 4526-94 C'l la nitrate 118 2948-06 .. : :: C d N^ oxide . . 64 1593-54 C* phosphate 92 2485-84 c d "p phosphuret 68 sulphate - 104 2595-86 (3 d Si sulphuret * . 72 1795-86 C d S^ Calcium 20 512-06 Ca chloride 56 1397-36 Cn M* fluoride 36 987-09 Ca I'' iodide .-.'{. 145 3645-46 Ca Y* oxide (lime) .... 28 712-06 Ca phosphuret 32 904-36 Ca P ? sulphuret 36 rr2 EQU 436 EQU Substances- Hydrogen 3=1. Oxygen = 100. Symbols. Calomel 236 2974-25 H M Camphoric acid .... p Carbon > *.-? . 6 75-33 C perchloride 120 protochloride .... 42 subchloride ~ ? .^~ 48 hydrochloride .... 50 oxide ;'" 'V.^r . ' 14 175-33 C phosphuret 18 sulphuret . 38 477-65 G& Carbonic acid 22 27533 C oxide \ ? . /-- 14 Carburet of azote .... 26 1 V, 38 phosphorus 18 Carburetted hydrogen 8 101-86 H4C Cerium . .-.. . ' * " . 46? 1149-44 Ce Chloric acid -..!, 76 Chlorine - . . , ..... 36 221-325 M Chromium 28 703-64 Ch deutoxide . r- 44 1103-64 Ch oxide ... . ' r . 36 1003-64 Ch Cobalt . ... . . : . 26 738-00 Co 84 96 2220-2 2378-77 Co A Co As benzoate . 154 3957-10 CoB* 56 1477-31 Co BS carbonate 56 1488-66 CoC 2 chloride 62 1623-3 CoM^ - citrate 92 2393-7 CoC* iodide 151 3871-4 Co'l^ nitrate v ._ . . . 88 2292-52 CoN oxalate . 70 1841-54 Co O peroxide p 1038-00 Co phosphate - ,.. . - . 62 1830-30 Co'p phosphuret ^\. 38 protoxide 34 938-00 Co EQU 437 EQU Substances. Hydrogen Oxygen = 100. Symbols. Cobalt, sulphate (dry) 74 1940-32 Co S crystallized (7 water) 137 sulphuret ." : -v* " . 42 1140-32 Co S* tartrate '- &tfi ' j. 101 2606-98 Co T* Columbium - '* 144? 1823-15 Ta Copper * V- G4 791-39 Cu acetate ... 130 22736 Cu A^ crystallized (6 w. com. verdigris) 184 binacetate .... 180 crystallized (3 w. dist. verdigris) 207 subacetate (1 acid 2 base) carbonate (anhydrous) 210 102 1542-05 Cu'c* (2 water malachite) 111 iodide ..... 189 3924-79 c'u'i^ perchloride pernitrate '- 136 188 167669 2345-91 Cu JO* CuN persulphate 160 199371 Cu S crystallized (10 water) 250 perphosphate .... 136 1883-69 CuP phosphuret protochloride .... 76 100 1234-04 CuM protoxide . 72 891-39 Cu peroxide ..... 80 991-39 Cu sulphuret x ' * , 80 992-55 CuS Corrosive sublimate 272 Cyanogen I-'. ' 26 Fluorine 16 75-03 FI Olucina 26 96256' Be Glucinum *.,,. Gold - - -* ' 4* 4 18 OAA 662-56 rt A no f\f\ Be chloride ... x i . ; JUU 236 J4OO-00 3813-95 Au Au Ms iodide ^> _ * >; - , 325 protoxide 1 -f 1 = ' * - 208 2586-00 Au peroxide 1 -f- 3 = ; ; 224 2786-00 Au sulphuret 1 + 3 = . f{ 248 3089-48 Au S* chloride of, and sodium (dry) 29 crystallized (8 water) . 368 EQU 438 EQU Substances. Hydrogen B=l. Oxygen = 100. Symbols. Hydrogen . ' >: ^\f 1 6-2177 H Iodine |. - "* 125 1266-7 I Iron * . . . ' , ..j 28 678-43 Fe protochloride - ../* **. 64 156373 Fe M 2 perchloride 82 2006-38 Fe M3 40 978-43 Fe protoxide - * 36 878-43 Fe sulphate (dry) - 76 2481-91 FeS3 crystallized (7 water) 139 persulphuret - 60 1483-07 FeS4 protosulphuret 44 1080-75 FeS> Lead : ;. r 104 2589-00 Pb acetate 162 4071-2 Pb A* crystallized (3 water) . 189 sub-binacetate . : 274 sub-tritacetate 386 9649-2 Pb3 A* arseniate 174 4229-77 PbAs benzoate f *' 232 5808-10 PbB borate ' ' '' - ^ : * J 134 3328-31 PbB^ carbonate 134 3339-33 PbC^ chlorate - * ' . 188 chloride . . 140 3474-3 Pb M chromate ''. 164 4092-64 PbCh I/O 4244t70 PbC 2 deutoxide 116 2889-00 Pb iodate ' !? 277 5722-4 Pb i iodide 229 5722-4 Pb'l 2 . . malate 182 molybdate 184 4582-6 Pb Mo2 nitrate 166 4143-52 Pb'N oxalatc * - ' - 148 3692-54 PbO* ion onpo AA pu nMi AitOiJ'W X D phosphate 140 3681-30 Pb'p phosphite 132 3481-30 Pb P phosphuret 116 112 57RQ.OO Pb EQU 439 EQU Substances. Hydrogen "= 1. Oxygen = 100. Symbols. Lead, succinate ... 162 4044-70 Pbs"* sulphate 152 3791-32 PbS sulphite 144 3591-32 Pb S sulphuret 120 . 2991-32 PbS* 179 4457.00 Pb T * Lime 1 fif 28 Tt^itJ^ *JO 712-06 Ca acetate 78 1994-3 CaA 2 arseniate 90 2152-83 Ca As benzoate 148 3731-16 CaB^ biphosphate .... 84 2496-66 Ca'pi borate 50? 1251-37 GB* 50 1262-72 Ca C chlorate 104 2597-36 CaM' chloride * ' 64 1397-36 CaM^ citrate - - . . 86 2167-76 CaC 2 chromate 80 2015-70 CaCh hydrate 37 936-93 Ca -f 2Aq 193 4845-46 Ca I' 2 muriate crystallized (5 water) 110 oxalate - - - ' - 64 1615-58 CaO 2 phosphate ' 56 1604-36 Ca *P phosphite 48 1404-36 Ca 'P succinate 78 1967-76 CaS 2 sulphate 68 1714-38 iisi crystallized (2 water) 86 sulphite .... 60 1514-38 Ca S 2 tartrate '.*..' 95 2381-04 CaT 148 3727-44 CaW^ Lithia 18 455-63 L carbonate " 40 1006-29 LC 2 nitrate .*-*.' | : .''.>.' 72 1810-15 L N phosphate 46 1347-93 LP . , 58 1457-95 LSi Lithium 10 255-63 L chloride - ; 46 1140-93 LJB1' - iodide 135 3389-03 LI' sulphuret 26 EQU 440 EQU Substances. Hydrogen Oxygen = 100. Symbols. Magnesia *' | '-*' 20 516-72 Mg ammonia-phosphate > 4 93 borate? ' * ' . U *' - 42 1056-03 ivigB carbonate.- "* - '- * 42 1067-38 MgC* hydrate . N ^v-" . ' v^ 29 741-59 Mg + 2Aq muriate '*' '-*' 57 74 1871 94 Mg N phosphate '5^ - 48 lOt I'^t 1409-02 O Mg'P sulphate (dry) 60 1519-04 Mg'i crystallized (7 water) 123 tartrate '.. 87 2185-70 Mg T* Magnesium 12 316-72 Mg chloride 48 1202-02 Mg M 2 iodide 137 3450-12 jvig i phosphuret 24 sulphuret -..; 28 28 t\j Of? 711-57 n- oO 2935-0 Mn A3 1 <^R ... lot> 5540-22 Mn JS3 carbonate 58 1462-33 Mn C 2 112 nHfif* o>7 TVTn 1VT'2 i ^/yo-o7 ivin ivi* 64 1 ^Qfi ft*7 MnM* ioyt)-o/ citrate : ' 94 2467.27 MnC 2 40 . -iu^ I 1011 ^7 Mn oxalate .'.<-. 72 1 vl 1 O^ 2366-88 Mn O^ peroxide -. ;. :. iodide . . . . - HO 154 3872-91 JNl (J 2 Nil 2 nitrate ..... 91 2294-03 NiN 2 oxalate 73 1843-05 NiO 2 peroxide ? 1039-51 *Ni ? phosphate 65 1831-81 NiP* phosphuret 41 protoxide 37 939-51 Ni sulphate (dry) 77 1941-83 NiS* crystallized (7 water) 140 Afi 1141 *Vl Ni S 2 4O IrtJ. 1 141 -do Ni T 2 Nitric oxide - . . 1U4 30 377-26 'N Nitrogen - ' ; - .^ . 14 177-26 N Nitrous oxide . ^ . ' . Olefiant gas - . . 22 277-26 N Osmium Os ? Oxygen rc'T'v r I 102 EvZV^OU 3661-37 AS K As 2 ifift . _ 1DO 4iJo-yj Ka B* bicarbonate .... 92 2281-15 KC4 crystallized ( 1 water) 101 bichromate .... 152 binarseniate - - - 172 4061-37 K As binoxalate 120 2986-91 KO4 biphosphate .... 104 2964-43 kp^ bisulphate 128 3184-47 ks4 crystallized (1 water) 137 bitartrate > 182 4517-79 KT4 crystallized (1 water) 191 borate ..... 70? 1719-14 kii^ 70 17^0.40 k C2 / v 1 /OU ^t*7 chlorate 124 3065-13 K M^ chromate 100 2483-47 kcii Iftfi 9r^ c i * KT^-j 1UO *17 ' 4J Ki r) m <>/ u 70 ~r "Aq 21^ KQ1Q.OQ KTrt a la vOlO-^O I- raolybdate 120 2973-43 K Mo* 10- 2uo4-oo k N :J EQU 443 EQU Substances. Hydrogen Ox\ Symbols. Potash, oxalate .... 84 phosphate 4 . 76 quadroxalate .... 192 succinate ; .*~~ t f. *\ ;> 98 sulphate 88 sulphite ~r>' . ... . 80 tartrate '.-. . . 115 tungstate ; ; 168 Potassium ... - . 40 chloride ..... 76 iodide .* "-' . . . 166 peroxide ' : 64 phosphuret . : . . . 52 protoxide (dry) 48 sulphuret ' - 56 Rhodium i" ' . . . 44? peroxide 60 protoxide ''<* . ; J i' . 52? Selenium? .JU-CfifS . ,'-.- . 41 Silica . ., ". . .. . 16 Silicium .; " . . : . . -. . 8 Silver . . . . . no acetate .... . 168 arseniate . ' . 180 arsenite .;... . . 172 benzoate . . ",>*:; ^> : 238 borate? ;f>r[ ,f : 140 carbonate 140 chlorate LvHf I ' 194 chloride -Y^ ;. : 146 chromate ; '. ' 1 !- t 170 citrate ' ?^ ''< 176 iodate . .. , > 283 iodide .... j; 235 molybdate 190 nitrate < 172 oxalate . . . j 154 2083-37 2072-13 4793-99 2435-53 2182-15 1982-15 2848-81 4195-21 979-83 1865-13 4113-23 1579-83 1372-13 1179-83 1382-15 1500-10 1800-10 1600-10 495-91 596-42 296-42 2703-21 4185-45 4343-98 5384-75 5922-31 3442-52 3453-87 4788-51 3588-51 4206-85 4358-91 7036-61 5836-61 4696-81 4257-73 3806-75 KO KP KO 8 s* KT* k w* K KM* k i "K KP* k KS* R R R Se 'si Si Ag Ag A* AgAs AgAs AgC AgMi AgM* AgCh Agp Ag"l> Agl 2 Ag Mo 2 AgN AgO* EQU 444 EQU Substances. Hydrogen Oxygen = 1 ' EQU 445 EQU Substances. Hydrogen Oxygen -=100. Symbols. Sodium, sulphuret 40 984-16 NaS* Starch ? 142 Strontia { 52 1294-60 Sr acetate 102 2576-8 s'rA* borate? . ; -*t'. 74 1833-91 S'rB* 74 1845-26 Sr C 2 citrate / ** 110 2750-3 S'r5> hydrate 61 1521-13 Sr + 2Aq muriate, crystallized (5 water) 134 oxalate 88 2198-14 Sr O 2 phosphate . ' * 80 2186-90 Sr'P sulphate 92 2296-92 Sr S* tartrate - , - ; , 119 2963-58 SrT^ Strontium 44 1094-60 Sr chloride .... 80 1979-91 Sr M 2 iodide . .., . - .. 169 4228-0 Sr i' 2 phosphuret .... 56 sulphuret 60 Sugar -, ? S 1 h 16 201-16 S oujpnur carburet ..... 38 477-65 CS 2 chloride 52 iodide - - 141 phosphuret .... 28 Sulphuretted hydrogen 17 213-60 H^S Tannin? ... 71 38 806-45 Te chloride - - 74 1691-75 Te M 2 oxide , ., * :*>-, 46 1006-45 Te Tin ... ;| 58 1470-58 Sn bisulphuret .... 90 2275-22 SnS4 iodide . ;^ .. . . . 183 4603-98 SnI 2 . 74 IftTft ^ft Sn protoxide ^ . | 66 lo/U-Oo 1670-58 'Sn perchloride ... . v ' 130 3241-18 *Sn M* protochloride - - - * ^ 94 2355-88 Sn M 2 EQU 446 EQU Substances. Hydrogen 1. Oxvpen = 100. Symbols. Tin, sulphuret - - !i . 74 1872-90 M* phosphuret ~t i ^N * 70 Titanium ^ .! '" * t - ? p Ti Tungsten . .' : 96 1207-69 W Tungstic acid 120 1507-69 W Uranium - ? ? 3146-86 U oxide - - - '' ? 3346-86 i) Uric acid . I -i f */ !> borate 10 64 1545-76 /.n is* Zn b 2 carbonate . - 64 1557-11 Zn C chlorate and, if necessary, check the violence of the ebullition by the application of a moist sponge, or rag, to the retort. The operation is finished when it spontaneously ceases to boiL By this time the product forms a little more than one* third of the alcohol and acid employed. But ether is not the sale product of the operation. We obtain also much protoxide of azote and water, a little azote, deutoxide of azote, carbonic acid gas, nitrous acid gas, acetic acid, and a substance easily carbonized. We are thus led to suppose that a portion of the alcohol is completely decomposed by the nitric acid ; that it yields almost all its hy- drogen to the oxygen of this acid ; and that hence result all the products, besides the ether, whilst the alcohol and the nitrous acid unite to constitute the ether properly so called. The whole ether comes over as well as the azote>. 00 ETH 450 ETH protoxide of azote, deutoxide of azote, and carbonic acid. As to the water, nitrous and acetic acids, they are disei: gaged only in part, as well as a portion of the alcohol and nitric acid which escape their reciprocal action. In fact, the easily charred matter remains in the retort along with a little acetic acid, about 78 parts of nitric acid, 60 of alcohol, and 284 of water, supposing that we had operated upon 500 parts of alcohol and as much dilute nitric acid. It is because there is formed so great a quantity of gas, that the salt water and refri- geration are required. Without these pre- cautions, the greater part of the ether would be carried off into the atmosphere; and, even with them, some is always lost. On unluting the apparatus, there is found in the first bottle a large quantity of yellow- ish liquid, formed of much weak alcohol, of ether, with nitrous, nitric, and acetic acids. In the second, we find on the surface of the salt water a pretty thick stratum of ether, contaminated with a little acid and alcohol. In the third, a thinner layer of the same, and so on. These layers are to be separated from the water by a long-necked funnel, mixed with .,:"* the liquid of the first bottle, and redistilled from a retort by a gentle heat, into a receiver surrounded with ice. The first product is an ether, which may be entirely deprived of acid, by being placed in contact with cold quick- lime in a phial, and decanted off it in about half an hour. From a mixture of about 500 parts of alcohol, and as much acid, about 100 parts of excellent ether may be procured. Nitric ether in its ordinary state is a liquid of a yellowish- white colour. It has an odour analogous to that of the preceding ethers, but much stronger, so that its inhalation into the nostrils produces a species of giddiness. It does not redden litmus. Its taste is acrid and burning. Its sp. gr. is greater than that of alcohol, and less than that of water. It boils at 70 F., or at that temperature sustains a column equal to 30 inches of mercury. Poured into the hand, it immediately boils, and creates considerable cold. It is sufficient to grasp in our hands a phial containing it, to see bubbles immediately escape. It takes fire very readily, and burns quite away, with a white flame. When agitated with 25 or 30 times its weight of water, it is divided into three por- tions. One, the smallest, is dissolved; an- other is converted into vapour ; and a third is decomposed. The solution becomes suddenly acid ; it assumes a strong smell of apples ; and if, after saturating with potash the acid which it contains, it be subjected to distillation, we withdraw the alcohol, and obtain a residue formed of nitrate of potash. We see here that there is a separation of one part of the two bodies which constitute the ether. Left to itself in a well stopped bottle, the ether suffers a spontaneous change, for it becomes percep- tibly acid. By distillation, acid is instantly developed, which shows that heat favours its decomposition. If, instead of exposing the nitric ether to a distilling heat, we make it traverse an ignited tube, it is completely de- composed. 41.5 parts of ether thus decom- posed yielded 5.63 water, containing a little prussic acid ; 0.40 of ammonia ; 0.80 oil ; 0.30 of charcoal; 0.?5 carbonic acid; 29.9 of gases, formed of deutoxide of azote, azote, subcarburetted hydrogen, and oxide of carbon. The loss amounted to 3-72. It is very slowly decomposed by potash. When combined with nitrous acid gas or acetic acid, so intimate a union is effected, that in making the compound pass through the most concentrated alkalis, only a small portion of its acid is separated. Nitric ether, from its great volatility, quintuples the volume of oxygen gas at ordinary temperatures. We possess no exact analysis of nitrous ether. Hydriodic ether. M. Gay Lussac, to whom the formation of this ether is due, obtained it by mixing together equal bulks of alcohol and a coloured hydriodic acid, sp. gr, 1.700, dis- tilling the mixture by the heat of a water bath, and diluting with water the product which gra- dually collects in the receiver. The ether pre- cipitates in the form of small globules, which have at first a milky aspect, but which by their union form a transparent liquid. It is purified by repeated washings with water. This ether does not redden litmus ; its smell is strong, and analogous to that of the rest. Its sp. gr. is 1.9206 at 72 F. It assumes in the course of a few days a rose colour, which becomes no deeper by time, and which mer- cury and potash instantly remove, by seizing the iodine which occasions it. Hydriodic ether boils at 156 F. At or- dinary temperatures, it does not kindle by the approach of a lighted taper to its surface, but only exhales purple vapours, when poured drop by drop on burning coals. Potassium, keeps in it, without alteration. Potash does not instantaneously change it. The same may be said of nitric and sulphurous acids, as well as chlorine. By passing it through an incan- descent tube, it is converted into a carburetted inflammable gas ; into dark brown hydriodic acid; into charcoal ; and flocculi, whose odour is ethereous, and which M. Gay Lussac con- siders as a sort of ether, formed of hydriodic acid, and of a vegetable product different from alcohol. These flakes melt in boiling water, and assume on cooling the transparency and colour of wax. They are much less volatile than hydriodic ether, and evolve much more iodine when projected on glowing coals. Ethers from vegetable acids. Almost all the vegetable acids dissolve in alcohol, and separate from it again by distillation, without any peculiar product being formed, however ETH 451 ETH frequently we act upon the same quantity of acid and alcohol. Such is the case at least with the tartaric, citric, malic, benzoic, oxalic, and gallic acid. But this cannot be said of the acetic. The action of this acid on alcohol is such, that by means of repeated distillations, the two bodies disappear, and form a true ether ; whence it has been inferred by M. Thenard, that this fluid is probably the only one of the vegetable acids at present known, which can exhibit by itself the phenomena of etherization. But if instead of putting the vegetable acids alone in contact with alcohol, we add to the mixture one of the concentrated mineral acids, we can then produce with several of them compounds analogous to the preceding ethers. The mineral acid probably acts here by con- densing the alcohol, and elevating the tem- perature, to such a degree as to determine the requisite chemical reaction. Acetic ether was discovered by Scheele, but first accurately examined by M. Thenard. Take 100 parts of rectified alcohol, 63 parts of concentrated acetic acid, 17 parts of sul- phuric acid of commerce. After having mixed the whole, introduce them into a tubulated glass retort, connected with a large globular receiver surrounded with cold water. On ap- plying heat, the liquid enters into ebullition ; and when 123 parts of ether have passed over, the process may be stopped. To render it per- fectly pure, we have only to place it, for half an hour, in contact with 10 or 12 parts of the caustic potash of the apothecary, in a corked phial, and to agitate from time to time. Two strata will form; the undermost thin, com- posed of potash and acetate of potash dissolved in water; the uppermost much more con- siderable, consisting of pure ether, which may be separated by a long-necked funnel. The sulphuric acid does not enter at all into the composition of this ether. It merely favours the reaction of the alcohol and acetic acid. This mode is much better than the old one, of distilling many times over the same mixture of acetic acid and alcohol. Or we may obtain an excellent acetic ether, very economically, by taking 3 parts of acetate of potash, 3 of con- centrated alcohol, and 2 of oil of vitriol ; in- troducing the mixture into a tubulated retort, and distilling to perfect dryness ; then mixing the product with the fifth part of its weight of oil of vitriol, and, by a careful distillation, drawing offas much ether as there was alcohol employed. Acetic ether is a colourless liquid, having an agreeable odour of sulphuric ether and acetic acid. It does not redden litmus paper, or tinc- ture of turnsole. Its taste is peculiar. Its sp. gr. is 0.866, at 44.5 F. Under the ordinary atmospheric pressure, it enters into ebullition at 100 Fahr. A lighted taper brought near its surface at ordi- nary temperatures sets fire to it, and it burns with a yellowish-white flame. Acetic acid is developed in the combustion. It is not changed by keeping. Water at 62 dissolves 7i parts of its weight. When thus dissolved in water, it exercises no action on litmus, and it pre- serves its characteristic odour and taste. But when this solution is put in contact with the half of its weight of caustic potash, its odour and taste disappear. It is now completely decomposed. Henee, if we submit this liquid to distillation, alcohol passes over, and acetate of potash remains. Acetic ether is, like all the others, very soluble in alcohol, and se- parable from alcohol by water. Its other properties are unknown. It is used only in medicine, as an exhilarant and diuretic. Benzoic ether. The presence of a mineral acid is indispensable to Us formation, as well as that of the remaining vegetable ethers. Take 30 parts of benzoic acid, 60 of al- cohol, 1 5 of strong muriatic acid. Introduce these ingredients mixed together into a tu- bulated retort, and distil into a refrigerated receiver, stopping the operation when two- thirds have passed over. Atmospherical air, and traces of muriatic acid, are the only gas- eous products. The first portion of the liquid is alcohol charged with a little acid, but the last will contain a certain quantity of benzoic ether, which is easily separable by water. A larger quantity of this ether remains in the re- tort, covered by a pretty thick stratum, con- sisting of alcohol, water, muriatic and benzoic acids. By repeated affusions of hot water into the retort, this stratum will be finally dissolved. It is easy thus to procure benzoic ether. But as so made, it is always contaminated with a portion of benzoic acid, which renders it so- lid at ordinary temperatures, and makes it act on litmus. It may be purified by agita- tion with a small quantity of alkaline solution, and subsequent washing with water. There is no muriatic acid found in this purified ether. Ethers from oxalic acid, citric, $c. When we make a solution of 30 parts of oxalic acid in 35 parts of pure alcohol, and having added 10 parts of oil of vitriol, we subject the whole to distillation till a little sulphuric ether begins to be formed, we shall find that nothing but alcohol slightly etherized has passed into the receiver, and there remains in the retort a brown-coloured strongly acid liquor, from which, on cooling, crystals of oxalic acid fall down. But when we dilute the residual liquor with water, a matter is separated similar to what the benzoic acid yielded, scarcely soluble in water, very abundant^ and which is obtained pure by washing it with cold water, and re- moving, by a little alkali, the excess of acid which it retains. If we treat in the same way the citric and malic acids, we obtain similar products. The three substances resulting from these three acids have analogous properties. They are all yellowish, somewhat heavier than water, void of smell, perceptibly soluble in water ? 002 ETH 452 EVA and very soluble in alcohol, from which they are precipitated by water. They differ from each other in taste. That made from oxalic acid is faintly astringent ; that from the citric acid is very bitter. The first is the only one which is volatile ; it is vaporized with boiling water, and by this means it is easily obtained white. When heated with a solution of caustic potash, they are all three decomposed, and yield alcohol, along with their peculiar acids ; but no trace of sulphuric acid. Tartaric acid is also susceptible of combin- ing with alcohol like the preceding acids. But it presents some curious phenomena. The ex- periment, of its formation, must be conducted in the same way as with oxalic acid. We must employ 30 parts of tartaric acid, 35 of alcohol, 10 of oil of vitriol, and distil the mixture till a little sulphuric ether begins to be formed. If at this period we withdraw the heat from the retort, the liquor will assume a syrupy consistence by cooling. But in vain shall we pour in water, in hope of separating, as in the preceding cases, a peculiar combina- tion of the vegetable acid and alcohol. But let us add by degrees solution of potash, we shall throw down much cream of tartar ; then, after having just saturated the redundant acid, if we evaporate the liquid, and treat it in the cold with very pure alcohol, we shall obtain, by evaporation of the alcoholic solution, a sub- stance which, on cooling, will become more syrupy than the matter was, before being treated with potash and alcohol. This sub- stance, which is easily prepared in considerable quantity, has a brown colour, and a very bitter and slightly nauseous taste. It is void of smell and acidity, and is very soluble in water and alcohol. It does not precipitate muriate of lime, but copiously the muriate of barytes. When calcined it diffuses dense fumes, which have the odour of garlic, and at the same time it leaves a charcoaly residue, not alkaline, con- taining much sulphate of potash. Finally, if distilled with potash, it is resolved into a very strong alcohol, and much tartrate of potash. This substance is therefore a combination ana- logous to the preceding. But what is peculiar to it is its syrupy state, and the property it possesses of rendering soluble in the most con- centrated alcohol the sulphate of potash, which of itself is insoluble in ardent spirits. It is perhaps owing to this admixture of sulphate of potash, that it wants the oily aspect belonging to all the other combinations of this genus. These vegetable-acid ethers may be consi- dered either as compounds of acid and alcohol, or of the ultimate constituents of the former with those of the latter. Phosphoric and arsenic ethers are made from phosphoric and arsenic acids, and alcohol. They differ in no respect from sulphuric ether. Bouillay, Journal de Phamn. torn, i., and Lassaigne, Ann. de Chlm, ft dc Phys. torn, xiii, 294. ETHIOPS (MARTIAL). Black oxide of iron. ETHIOPS (MINERAL). The black sulphuret of mercury. ETHIOPS PER SB. Black oxide of mercury, formed by agitation with access of air. The term is obsolete. EVAPORATION. A chemical operation usually performed by applying heat to any compound substance, in order to separate the volatile parts. It differs from distillation in its object, which chiefly consists in preserving the more fixed matters, while the volatile sub- stances are dissipated and lost. And the vessels are accordingly different ; evaporation being commonly made in open shallow vessels, and distillation in an apparatus nearly closed from the external air. The degree of heat must be duly regulated in evaporation. When the fixed and more volatile matters do not greatly differ in their tendency to fly off, the heat must be very care- fully adjusted ; but in other cases this is less necessary. As evaporation consists in the assumption of the elastic form, its rapidity will be in proportion to the degree of heat, and the dimi- nution of the pressure of the atmosphere. A current of air is likewise of service in this process. In treating of alum, I alluded to a method of evaporating liquors lately introduced into large manufactories. A water-tight stone cistern, about three or four feet broad, two feet deep, and 20, 30, or 40 feet long, is covered above by a low brick arch. At one extremity of this tunnel a grate is built, and at the other a lofty chimney. When the cistern is filled, and a strong fire kindled in the reverberatory grate, the flame and hot air sweep along the surface of the liquor, raise the temperature of the uppermost stratum, almost instantly, to near the boiling point, and draw it off in vapour. The great extent, rapidity, and economy of this proces, recommend it to ge- neral adoption on the large scale. Mr. Barry has lately obtained a patent for an apparatus, by which vegetable extracts for the apothecary may be made at a very gentle heat, and in vacua. From these two circum- stances, extracts thus prepared differ from those in common use, not only in their physical, but medicinal properties. The taste and smell of the extract of hemlock made in this way are remarkably different, as is the colour both of the soluble and feculent parts. The form of apparatus is as follows : The evaporating pan, or still, is a hemi- spherical dish of cast-iron, polished on its inner surface, and furnished with an air-tight flat lid. From the centre of this a pipe rises, and bending like the neck of a retort, it forms a declining tube, which terminates in a copper sphere of a capacity three (four?) times greater than that of he still. There is a stop- EVA 453 EVA Cock on that pipe, midway between the still and the globe, and another at the under side of the latter. The manner of setting it to work is this : The juice, or infusion, is introduced through a large opening into the polished iron still, which is then closed, made air-tight, and covered with water. The stop-cock which leads to the sphere, is also shut. In order to produce the vacuum, steam, from a separate apparatus, is made to rush by a pipe through the sphere, till it has expelled all the air, for which five minutes are commonly sufficient. This is known to be effected, by the steam issuing uncondensed. At that instant the copper sphere is closed, the steam shut off, and cold water admitted on its external surface. The vacuum thus produced in the copper sphere, which contains four-fifths of the air of the whole apparatus, is now partially trans- ferred to the still, by opening the intermediate stop-cock. Thus, four-fifths of the air in the still rush' into the sphere, and the stop-cock being shut again, a second exhaustion is effected by steam in the same manner as the first was ; after which, a momentary commu- nication is again allowed between the iron still and the receiver ; by this means, four-fifths of the air remaining after the former ex- haustion, are expelled. These exhaustions, repeated five or six times, are usually found sufficient to raise the mercurial column to the height of 28 inches. The water bath, in which the iron still is immersed, is now to be heated, until the fluid that is to be inspissated begins to boil, which is known by inspection through a window in the apparatus, made by fastening on, air-tight, a piece of very strong glass ; and the temperature at which the boiling point is kept up, is determined by a thermometer. Ebullition is continued until the fluid is in- spissated to the proper degree of consistence, which also is tolerably judged of by its ap- pearance through the glass window. The temperature of the boiling fluid is usually about 100 F., but it might be reduced to nearly 90. In the autumn of 1821, Mr. Barry showed M. Clement and myself the details of his evaporatory apparatus, with the ingenuity and performance of which we were highly satisfied. Learning since that he had made some further improvements, I solicited him to favour me with a description and drawing of its present form, for insertion in the second edition of this Dictionary ; with which request he politely complied. In the Medico-Chirurgical Transactions for 1819, (vol. x.) there is a paper by J. T. Barry on a new method of preparing Pharmaceutical Extracts. It consists in performing the eva- poration in vacuo. For this purpose he em- ployed apparatus which was found to answer so well, that, contemplating its application to other manufactures, t was induced to take out a patent for it, that is to say, for the apparatus. As it has been erroneously sup- posed that the patent is for preparing extracts in vacuo, it may not be hnproper to correct the statement by a short quotation from the above paper. " On that account, I have been in- duced to take outa patent for it, (the apparatus). It is, however, to be recollected by this society, that I have declined having a patent for its pharmaceutical products. Chemists, desirous of inspissating extracts in vacuo, are therefore at liberty to do it in any apparatus differing from that which has been made the subject of my patent ; and thus these substances may continue the object of fair competition as to quality and price." The apparatus combines two striking im- provements. The first consists in producing a vacuum by the agency of steam only, so that the use of air-pumps and the machinery re- quisite for working them, is superseded. This is effected on the same principle as in the steam-engine, the filling of a given space with steam, and then condensing it. By a subse- quent improvement, the two operations of heating and cooling are carried on at once, by means of two cylinders. The movement of a sliding valve, which serves to open and shut the respective passages, . causes these exhausting cylinders to alternately communicate with the apparatus, and quickly produce the vacuum ; when the steam, being no longer required for the same purpose, is employed as the heating medium. The other improvement is a contrivance for superseding the injection of water during the process of evaporation in vacuo. Injection has some serious disadvantages ; it introduces air, and quickly fills up the exhausted vessels with water. Hence it is necessary to keep pumps constantly in action, and this cannot be done without an enormous expenditure of power, because they are counteracted by the atmo- spheric pressure. The method recommended by J. T. Barry, devoid of these inconvenienciep, effects quite as speedily the condensation of vapour, by cold externally applied to a part denominated the refrigerator, which stands immersed in water. He directs a thin sheet of metal to be indented all over at suitable distances, so as to produce on its opposite surface regular series of convexities. It is then ; laid on a sheet of the same size, and the two being in contact at the summits of the convex- ities, are approximated and soldered together at the edges of the sheets all round, reserving an aperture at the upper part for the admission of vapour, and another at the lowest point for its escape when reduced to fluid. This de- scription of the refrigerator will be understood on reference to Plate X. fig. 2 ; but the spe- cification of the patent describes various other methods of effecting the same object, taking for its principle, the " letting the two sides of the refrigerator rest against each other at EVA 454 V EUD numerous parts, (cither immediately, or by the medium of one or more interposed bodies), so that they shall not collapse entirely when the refrigerator is exhausted- of air." Having given a particular description of the refrigerator, and the mode of exhausting the apparatus, a few words will suffice to explain the other parts. Plate VII. fig. 1. shows one of the evaporating vessels A, with its cistern B, and refrigerating plates. The cistern is kept cool after the manner of a distiller's worm- tub. The evaporating vessel is furnished with several appendages, such as, the charging measure c, and discharging pipe d, which is moved perpendicularly by its lever ; man-hole g, and chamber^ for catching any fluid that may chance to boil over : it is surrounded at the lower part with a steam-case e, for boiling its contents. There is also a vacuum-gauge, &c. not delineated in the section. Thus far the arrangement does not differ materially from that adopted by the sugar-refiners manu- facturing under Howard's patent. A pipe TW, passing from the chamber^ into the cistern, gives origin to several refrigerating plates, (seven in the present instance), which have their lower extremities terminating in another pipe n. The transverse section in fig. 1. exhibits these plates upright and parallel with each other in the cold water cistern; they occupy very little room, and may there- 7 fore be multiplied to an indefinite number, to furnish a proportionate quantity of cooling surface. On entering these, the vapour is in- stantly condensed, and dropping into the lower pipe, is conducted to a cylindrical receiver, shown by the transverse section 7^. It is of sufficient capacity to collect all the fluid con- densed during the process. Fig. 3. represents a series of evaporators (drawn to half the scale of fig. 1.) as arranged for a sugar-house. It will be observed, that one long cistern serves for the whole, and it may be situated outside the walls of the build- ing. A single pair of exhausting steam-cy- linders, (which, being under the cistern, are not seen in the sketch), answers for any num- ber of evaporators, having with each a separate connexion, that is shut or opened at pleasure by a sliding valve. We shall conclude the account of this in- vention with Mr. Barry's summary remarks, inserted in the Repertory of Arts at the time the editors of that work published the specifi- cation. " The apparatus described in the preceding specification is applicable to some manufac- tures, where the substances operated upon suffer injury in the process of boiling, but especially to sugar; and it is particularly worthy the notice of those sugar-refiners who may be likely to adopt the use of Howard's patents, as it will afford them some very im- portant advantages. " These advantages principally consist in, '* First, The small cost of the apparatus, no air-pumps or other machinery being neces- sary. " Secondly, The saving of large annual ex- penses, hitherto incurred for supplying power to work the heavy machinery attached to the pumps. " Thirdly, Expensive repairs avoided, as a consequence. " Fourthly, Danger of derangement and suspension of work avoided, as another conse- quence. " Fifthly, A large saving of water, by the use of a peculiar refrigerator, which consti- tutes one of the improvements of this patent. " Sixthly, The facility with which the va- cuum is obtained; the operation being com- pleted in less than five minutes, and requiring no repetition : And the perfection of tfie va- cuum ; the patentee in his experiments having boiled syrup at even lower temperatures than are provided for in the scale adopted by Howard." In the sixth volume of the Annals of Phi- losophy, Dr. Prout has described an ingenious apparatus, by means of which he can subject substances, which he wishes thoroughly to dry, to the influence of a gentle heat, conjoined with the desiccating power of sulphuric acid on bodies placed in vacua- See CONGELA- "" From M. Biot's report, it seems to have been ascertained in some French manufacto- ries, that evaporation goes on more rapidly from a liquid boiling in a covered vessel, from the top of which a pipe issues, than when the liquid is freely exposed to the air ; the fuel or heat applied, and extent of surface, being the same in both cases. EUCHLORINE. Protoxide of chlorine. EUCLASE. Prismatic Emerald. EUDIALITE. A mineral belonging to the tessular system of Mohs. Cleavage, octo- hedral. Brownish-red colour. Sp. gr. 2.8 to 3-0. Stromcyer. EUDIOMETER. An instrument for ascertaining the purity of air, or rather the quantity of oxygen contained in any given bulk of elastic fluid. Dr. Priestley's discovery of the great readiness with which nitrous gas combines with oxygen, and is precipitated in the form of nitric acid, see ACID ( NITRIC), was the basis upon which he constructed the first instrument of this kind. His method was very simple: a glass vessel, containing an ounce by measure, was filled with the air to be examined, which was transferred from it to a jar of an inch and a half diameter inverted in water ; an equal measure of fresh nitrous gas was added to it ; and the mixture was allowed to stand two minutes. If the ab- sorption were very considerable, more nitrous gas was added, till all the oxygen appeared to be absorbed. The residual gas was then trans- ferred into a glass tube two feet long, and one- EUD 455 EUD third of an inch wide, graduated to tenths and hundred ths of an ounce measure ; and thus the quantity of oxygen absorbed was measured by the diminution that had taken place. Von Humboldt proposes that the nitrous gas should be examined, before it is used, by agitating a given quantity with a solution of sulphate of iron. Sir H. Davy employs the nitrous gas in a different manner. He passes it into a saturated solution of green muriate or sulphate of iron, which becomes opaque, and almost black, when fully impregnated with the gas. The air to be tried is contained in a small graduated tube, largest at the open end, which is intro- duced into the solution, and then gently in- clined toward the horizon, to accelerate the action, which will be complete in*a few mi- nutes, so as to have absorbed all the oxygen. He observes, that the measure must be taken as soon as this is done, otherwise the bulk of the air will be increased by a slow decomposi- tion of the nitric aid formed. Volta had recourse to the accension of hy- drogen gas. For this purpose, two measures of hydrogen are introduced into a graduated tube, with three of the air to be examined, and fired by the electric spark. The diminution of bulk, observed after the vessel had returned to its original temperature, divided by three, gives the quantity of oxygen consumed. Phosphorus and sulphuret of potash have likewise been employed in eudiometry. A piece of phosphorus may be introduced by means of a glass rod into a tube containing the air to be examined standing over water, and suffered to remain till it has absorbed its oxygen ; which, however, is a slow process. Or a glass tube may be filled with mercury and inverted, and a piece of phosphorus, dried with blotting paper, introduced, which will of course rise to the top. It is there to be melted, by bringing a red-hot iron near the glass, and the air to be admitted by little at a time. At each addition the phosphorus inflames ; and, when the whole has been admitted, the red- hot iron may be applied again, to ensure the absorption of all the oxygen. In either of these modes l-40th of the residuum is to be deducted, for the expansion of the nitrogen, by means of a little phosphorus which it affords. Professor Hope of Edinburgh employs a very convenient eudiometer, when sulphuret of potash or Sir H. Davy's liquid is used. It consists of two glass vessels, one to hold the solution of sulphuret of potash, or other eudio- metric liquor, about two inches in diameter, and three inches high, with a neck at the top as usual, and a tubulure, to be closed with a stopple in the side near the bottom : the other is a tube, about eight inches and a half long, with a neck ground to fit into that of the former. This being filled with the air to be examined, and its mouth covered with a flat piece of glass, is to be introduced under water, and there inserted into the mouth of the bottle. Taking them out of the water, and inclining them on one side, they are to be well shaken, occasionally loosening the stopper in a basin filled with water, so as to admit this fluid to occupy the vacuum occasioned by the absorp- tion. Bottles of much smaller size than here mentioned, which is calculated for public ex- hibition, may generally be employed; and, perhaps, a graduated tube, ground to fit into the neck of a small phial, without projecting within it, may be preferable on many occa- sions, loosening it a little under water, from time to time, as the absorption goes on. Mr. Dalton has written largely on the ni- trous gas eudiometer. He says, that 21 mea- sures of oxygen can unite with 36 measures, or twice 36 72 measures of nitrous gas ; that is, 100 with 171.4 or 342-8. Phil. Mag. vol. xxiii. and Manch. Mem. new series, 1. M. Gay Lussac, in his excellent memoir on nitrous vapour and nitrous gas, has proved, that ho confidence can be reposed in the di- rections of Mr. Dalton for analyzing gases. Nitrous gas is there fully demonstrated to be a compound of equal volumes of oxygen and azote, and the apparent contraction of their volume is null ; for 100 of the one and 100 of the other produce exactly 200 of nitrous gas. Nitric acid is composed of 100 parts of azote, and 200 of oxygen, or of 1 00 oxygen and 200 nitrous gas; = (100 o. -f- 100 az.). Nitrous vapour, or, more accurately speaking, nitrous acid gas, results from the combination of 100 of oxygen with 300 of nitrous gas. Hence, t by giving predominance alternately to the oxygen and to the nitrous gas, we obtain 300 of absorption and nitric acid, or 400 of ab- sorption and nitrous acid. The nitrous s ci *: . % 0-9 Peculiar extractive matter, . 2-7 Salts, *!. . . . 1-2 Slimy matter, consisting of picro- mel, peculiar animal matter, and insoluble residue, <& . 14-0 100-0 The salts were to one another in the follow- ing proportions : Carbonate of soda, . 0-9 Muriate of soda, -; . -.* . 0*1 Sulphate of soda, -* . 0-05 Ammon. phos. magn. . . 0.05 Phosphate of lime, * . 0-1 Thaer and Einhof obtained, by ignition, from 3840 grains of the excrements of cattle, fed at the stall chiefly on turnips, the follow- ing earths and salts : Lime, . . * . .12 Phosphate of lime, v j, bile, and g-spsof, solid; sper- maceti is named cctine, from X>JTO?, a whale; the fatty substance and the oily substance, are named respectively, stearine, and elaine, from the words rs*f? fat, and tXanv, oil ; margarine, and the fluid fat obtained after saponification, are named margaric acid and olelc acid, while the term cetic acid is applied to what was named saponified spermaceti. The margurates, olcates, and cetates, will be the generic names of the soaps or combinations which these acids are capable of forming by their union with salifiable bases. Two portions of human fat were examined, one taken from the kidney, the other from the thigh : after some time they both of them manifested a tendency to separate into two distinct substances, one of a solid, and the other of a fluid consistence : the two portions differed in their fluidity and their melting point. These variations depend upon the dif- ferent proportions of stearine and elaine ; for the concrete part of fat is a combination of the two with an excess of stearine, and the fluid part is a combination with an excess of elaine. The fat from the other animals was then examined, principally with respect to their melting point and their solubility in al- cohol ; the melting point was not always the same in the fat of the same species of animal. When portions of the fat of different sheep are melted separately at the temperature of 122, in some specimens the thermometer descends to 98.5, and rises again to 102: while in others it descends to 104, and rises again to 106. A thermometer plunged into the fat of the ox melted at 122, descended to 98.5, and rose again to 102. When the fat of the jaguar was melted at 104, the thermometer descended to 84, and rose again to about 85 ; but a considerable portion of the fat still re- mained in a fluid state. With respect to the solubility of the different kinds of fat in al- cohol, it was found that 100 parts of it dis- solved 2.48 parts of human fat, 2.26 parts of sheep's fat, 2.52 parts of the fat of the ox, 2.18 parts of the fat of the jaguar, and about 2,8 parts of the fat of the hog. M. Chevreul next examines the change which is produced in the different kinds of fat respectively by the action of potash. All the kinds of fat are capable of being perfectly sa- ponified, when excluded from the contact of the air : in all of them there was the produc- tion of the saponified fat and the sweet prin- ciple ; no carbonic acid was produced, and the soaps formed contained no acetic acid, or only slight traces of it. The saponified fats had more tendency to crystallize in needles than, the fats in their natural state ; they were so- luble in all proportions in boiling alcohol of the specific gravity of .821. The solution, like that of the saponified fat of the hog, con- tained both the margaric and the oleic acids. They were less fusible than the fats from which they were formed : thus, when human fat, after being saponified, was melted, the ' thermometer became stationary at 95, when the fluid began to congeal; in that of the sheep, the thermometer fell to 118.5, and rose to 122; in that of the ox it remained stationary at 118.5 ; and in that of the jaguar at 96.5. The saponified fat of the sheep and the ox had the same degree of solubility in potash and soda as that of the hog. 100 parts of the fat of the") sheep when saponified v 15.41 of potash. were dissolved by j 100 parts of the saponified fat of the ox were dis- >- 15.42 of potash. solved by ) 100 parts of the same were ) , n , f A dissolved by < 10.24 of soda. 100 parts of the saponified ) fat of the hog were dis- > 15.04 of potash, solved by ) 100 parts of the same were ) , A Oft c , dissolved by < 10.29 of soda. The following table contains the proportions of the saponified fat, and of the matter soluble in water, into which 100 parts of the fat are capable of being changed: Human fat. Saponified fat, 95 Soluble matter, 5 Fat of the sheep. Saponified fat, 95-1 Soluble matter, 4-9 Fat of the ox. Saponified fat 95 Soluble matter, 5 Fat of the hog. Saponified fat, 94-7 Soluble matter, 5-3 M. Chevreul next gives an account of the analysis of fat by alcohol. The method of analysis employed was to expose the different kinds of fat to boiling alcohol, and to suffer the mixture to cool : a portion of the fat that had been dissolved was then separated in two states of combination ; one with an excess of stearine was deposited, the other with an excess of elaine remained in solution. The first was separated by filtration, and by distilling the filtered fluid, and adding a little water towards the end of the operation, we obtain the second in the retort, under the FAT 462 FAT form of an alcoholic aqueous fluid. The dis- tilled alcohol which had been employed in the analysis of human fat had no sensible odour ; the same was the case with that which had served for the analysis of the fat of the ox, of the hog, and of the goose. The alcohol which had been employed in the analysis of the fat of the sheep had a slight odour of candle- grease. The varieties of stearine from the different species of fat were found to possess the follow- ing properties: They were all of a beautiful white colour ; entirely, or almost without odour, insipid, and having no action upon lit- mus. Stearine from man. The thermometer which was plunged into it when melted fell to 105.5, and rose again to 120. By cooling, the stearine crystallized in very fine needles, the surface of which was fat.-r- Stearine of the sheep. The thermometer fell to 104, and rose again to 109.5; it formed itself into a flat mass: the centre, which cooled more slowly than the^ edges, presented small and finely- radiated needles Stearine of the ox. The thermometer fell to 103 and rose again to 11 1 ; it formed itself into a mass, the surface of which was flat, over which were dispersed a number of minute stars visible by the micro- scope ; it was slightly semitransparent. Stea- rine of the hog. It exhaled the odour of hog's-lard when it was melted. The ther- mometer fell to 100.5, and rose again to 109.5. By cooling, it was reduced into a mass, the surface of which was very unequal, and which appeared to be formed of small needles. When it cooled rapidly, the parts which touched the sides of the vessel had the semitransparency of coagulated albumen. Stearine of the goose. The thermometer fell to 104, and rose again to 109.5 ; it was formed into a flat mass. With respect to the solubility of these dif- ferent bodies in alcohol, 100 parts of boiling alcohol, of the specific gravity of 0.7952, dis- solved, Of human stearine, 21-50 parts. Of the stearine of the sheep, 16-07 Of the stearine of the ox, ] 5-48 Of the stearine of the hog, 18-25 Of the stearine of the goose, 36-00 Saponification by potash. The human stearine \ Saponified fat, produced, by saponi- J fication, . i goluble matt ^ { Saponified fat, Stearine ef the sheep. Soluble matter, _ - * Stearine of the C Saponified fat, 95-1^ ox. I Soluble matter, 4-9 1 r f Saponified fat, 94-65^ Stearine of the hog. i Soluble matter, ( 5-35 | ,- Stearine of the C Saponified fat, 94-J goose. L Soluble matter, 5-6 ( t It was fusible at 123-5 ; it crystal- 94-9 -\ lized in small needles joined in the form ^of a funnel. The syrup of the sweet principle weighed 8-6, the acetate 0-3*. f It began to become opaque at 129, Q , R l and the thermometer became stationary at t<0 ) 127-5; it crystallized in small fine ra- \. diated needles. {The syrup of the sweet principle weighed 8, the acetate 0-6 j it had a rancid odour. It began to become solid at 129, but it was not perfectly so until 125-5; it crystallized in small needles united into flattened globules. The syrup of the sweet principle weighed 9-8, the acetate 0-3- It began to grow solid at 129, and the thermometer became stationary at 125-5; it crystallized in small needles united into flattened globules. It became solid at 119; it crystal- lized in needles united in the form of a funnel. The syrup of the sweet principle weighed 8-2. * This means the salt which we obtain after having neutralized by barytes the product of the distillation of the aqueous fluid, which was procured from the soap that had been decomposed by tartaric acid. FAT 463 FEL All the soaps of stearine were analyzed by the same process as the soap of the fat from which they had been extracted: there was procured from them the pearly super-mar- garate of potash and the oleate ; but the first was much more abundant than the second. The margaric acid of the stearines had pre- cisely the same capacity for saturation as that which was extracted from the soaps formed of fat. The margaric acid of the stearine of the sheep was fusible at 144, and that of the stearine of the ox at 143-5 ; while the mar- garic acids of the hog and the goose had nearly the same fusibility with the margaric acid of the fat of these animals. On Spermaceti, or, as M. Chevreul tech- nically calls it, cetine. In the fifth memoir, in which we have an account of many of the properties of this substance, it was stated, that it is not easily saponified by potash, but that it is converted by this reagent into a substance which is soluble in water, but has not the sac- charine flavour of the sweet principle of oils ; into an acid analogous to the margaric, to which the name of cetic was applied ; and into another acid, which was conceived to be analogous to the oleic. Since he wrote the fifth memoir, the author has made the follow- ing observations on this subject: 1. That the portion of the soap of cetine which is insoluble in water, or the cetate of potash, is in part gelatinous, and in part pearly : 2. That two kinds of crystals were produced from the cetate of potash which had been dissolved in alcohol : 3. That the cetate of potash exposed, under a bell glass, to the heat of a stove, produced a sublimate of a fatty matter which was not acid. From this circumstance, M. Chevreul was led to suspect, that the supposed cetic acid might be a combination, or a mix- ture of margaric acid and of a fatty body i which was not acid. He accordingly treated a small quantity of it with barytic water, and boiled the soap which was formed in alcohol ; the greatest part of it was not dissolved, and the alcoholic solution, when cooled, filtered, j and distilled, produced a residuum of fatty ; matter which was not acid. The suspicion ! , being thus confirmed, M. Chevreul determined to subject cetine to a new train of experiments, i Being treated with boiling alcohol, a cetine was r procured, which was fusible at 120, and a \ yellow fatty matter which began to become 1 solid at 89-5, and which at 73-5 contained a 2 fluid oil, which was separated by filtration. Saponification of the Eldines by Potash. : The determination of the soluble matter which I the ela'ines yield to water in the process of i saponification, is much more difficult than the determination of the same point with respect I to the stearines. The stearines are less sub- ject to be changed than the ela'ines ; it is less 1 difficult to obtain the stearines in an uniformly ' pure state ; besides, the saponified fats of the stearines being less fusible than the saponified ela'ines, it is mo*e easy to weigh them without loss. The elaines of the sheep, the hog, the jaguar, and the goose, extracted by alcohol, yield by the action of potash, Of saponified fat, 89 parts Of soluble matter, 11 The elai'ne of the ox extracted in the same manner yields, Of saponified fat, 92-6 parts Of soluble matter, 7*4 The different kinds of fat, considered in their natural state, are distinguished from each other by their colour, odour, and fluidity. The stearines of the sheep, the ox, and the hog, have the same degree of solubility in alcohol ; the stearine of man is a little more soluble, while that of the goose is twice as much so. The elaines of man, of the sheep, the ox, the jaguar, and the hog, have a spe- cific gravity of about -915 ; that of the goose of about -929. The elaines of the sheep, the ox, and the hog, have the same solubility in alcohol ; the elai'ne of the goose is a little more soluble. On the other hand, the margaric acids of man, of the hog, of the jaguar, and of the goose, cannot be distinguished from each other ; those of the sheep and the ox differ a few degrees in their melting point, and a little also in their form. As for the slight dif- ferences which the oleic acids present, they are not sufficiently precise for us to be able to particularize them. See ACID (OLEic). M. Dupuy has shown that, in the distilla- tions of oils, if the temperature be not raised to ebullition, a solid product is obtained, which constitutes three-fourths of the quantity of oil employed ; while, if this point be exceeded, a liquid product is constantly formed, during the whole course of the operation. Thus with 100 parts of oil, the products were as follows : Solid Liquid Charcoal 76-470 23-529 3-676 103-67* The solid matter is of a consistence approach- ing that of hog's lard ; it is yellowish at the commencement of the operation, and of less consistence ; but by degrees it acquires more, and becomes of a very fine white colour. Annales de Chimie^ xxix. 319. FAT LUTE. A compound of linseed oil and pipe clay, of a doughy consistence. FECULA. See STARCH. FECULA. Green of plants. See CHLO- ROPHYLE. FELSPAR. This important mineralgenus is distributed by Professor Jameson into four species, viz. prismatic felspar, pyramidal fel- spar, prismato-pyramidal felspar, and rhom- boidal felspar. I. Prismatic felspar has 9 sub-species; 1. Adularia ; 2. Glassy felspar ; 3. Ice-spar; PEL 464 EEL 4. Common felspar ; 5. Labradore felspar ; 6. Compact felspar ; ?. Clinkstone ; 8. Earthy common felspar ; and, 9. Porcelain earth. 1. Adularia. Colour greenish-white ; iri- descent ; and in thin plates, pale flesh-red by transmitted light. Massive and crystallized. Primitive form ; an oblique four-sided prism, with 2 broad and 2 narrow lateral planes ; the lateral edges are 120 and 60. Secondary forms ; an oblique four-sided prism, a broad rectangular six-sided prism, a six-sided table, and a rectangular four-sided prism. Some- times twin crystals occur. The lateral planes of the prism are longitudinally streaked. Lustre splendent, intermediate between vitreous and pearly. Cleavage threefold. Fracture im- perfect conchoidal. Semitransparent. A beau- tiful pearly light is sometimes seen, when the specimen is viewed in the direction of the broader lateral planes. Refracts double. Harder then apatite, but softer than quartz. Easily frangible. Sp. gr. 2-5. It melts be- fore the blowpipe, without addition, into a white-coloured transparent glass. Its consti- tuents are, 64 silica, 20 alumina, 2 lime, and 14 potash. 1 VauqueUn. It occurs in contemporaneous veins, or drusy cavities, in granite and gneiss, in the island of Arran, in Norway, Switzerland, France, and Germany. The finest crystals are found in the mountain of Stella, a part of St. Gothard. Rolled pieces, exhibiting a most beautiful pearly light, are collected in the island of Ceylon. Moonstone adularia is found in Greenland ; and all the varieties in the United States. Under the name of moonstone it is worked by lapidaries. Another variety from Siberia is called sunstone by the jewellers. It is of a yellowish colour, and numberless golden spots appear distributed through its whole substance. These reflections of light are either from minute fissures, or irregular cleavages of the mineral. The aventurine felspar of Arch- angel appears to be also sunstone. It is the hyaloides of Theophrastus. 2. Glassy felspar. Colour greyish-white. Crystallized in broad rectangular four-sided prisms, bevelled on the extremities. Splendent and vitreous. Cleavage threefold. Fracture uneven. Transparent. Sp gr- 2.57- It melts without addition into a grey semi transparent glass. Its constituents are 68 silica, 15 alumina, 14-5 potash, and 0-5 oxide of iron Klapr. It occurs imbedded in pitch-stone porphyry in Arran and Rum. 3. Ice- spar. Colour greyish-white. Mas- sive, cellular and porous ; and crystallized in small, thin, longish six-sided tables. The lateral planes are longitudinally streaked. Lustre vitreous. Cleavage imperfect. Trans- lucent and transparent. Hard as common felspar, and easily frangible. It occurs along with nepheline, meionite, mica, and horn- blende, at Monte Somma near Naples. 4. Common felspar. Colours white and red, of various shades : rarely green and blue. Massive, disseminated and crystallized, in a very oblique four - sided prism ; an acute rhombus ; elongated octohedron ; a broad equiangular six-sided prism ; a rectangular four-sided prism ; and twin crystals ; which forms are diversified by various bevelments and truncations. Cleavage threefold. Lustre mote pearly than vitreous. Fracture uneven. Fragments rhomboidal; and have only four splendent faces. Translucent on the edges. Less hard than quartz. Easily frangible. Sp. gr. 2.57. It is fusible without addition into a grey semitransparent glass. Its con- stituents are as follows : Siberian green Flesh-red Felspar from felspar. felspar. Passau. Silica, 62.83 66-75 60-25 Alumina, 1?.02 17-50 22-00 Lime, 3-00 1-25 0-75 Potash, 13-00 12-00 14-00 Oxide of iron, 1-00 0-75 water, 1-00 96.85 Vauq. 98-25 Rose. 98.00 Bucholz. Felspar is one of the most abundant mi- nerals, as it forms a principal constituent part of granite and gneiss, and occurs occasionally mixed with mica-slate and clay-slate. It is also a constituent of whitestone and syenite. It forms the basis of certain porphyries. Greenstone is a compound of common felspar and hornblende. The most beautiful crystals of it occur in the Alps of Switzerland, in Lombardy, France, and Siberia, in veins of contemporaneous formation with the granite and gneiss rocks. It occurs abundantly in transition mountains, and in those of the se- condary class. Under the name of petunze, it is an ingredient of Chinese porcelain. When the green varieties are spotted with white, they are named aventurine felspar. Another green variety from South America is called the Amazon-stone, from the river where it is found. 5. Labradore felspar. Colour grey of va- rious shades. When light falls on it in certain directions, it exhibits a great variety of beau- tiful colours. It occurs massive, or in rolled pieces. Cleavage splendent. Fracture glisten- ing. Lustre between vitreous and pearly. It breaks into rhomboidal fragments. Translucent in a very low degree. Less easily frangible than common felspar. Sp. gr. 2-6 to 2-7. It is less fusible than common felspar. It occurs in rolled masses of syenite, in which it is as- sociated with common hornblende, hyperstene, and magnetic ironstone, in the island of St. Paul on the coast of Labradore. It is found round Laurwig in Norway. 6. Compact felspar. Colours, white, gray, green, and red. Massive, disseminated, and crystallized in rectangular four-sided prisms. Lustre glistening, or glimmering. Fracture FEU 465 FER splintery and even. Translucent only on the edges. Easily frangible. Sp. gr. 2.C9. It melts with difficulty into a whitish enamel. Its constituents are, 51 silica, 30-5 alumina, 11-25 lime, 1-75 iron, .4 soda, 1-26 water. Klapr. It occurs in mountain masses, beds and veins: in the Pentland hills, at Sala, Dannemora, and Hallefors in Sweden ; in the Saxon Erze-gebirge, and the Hartz. 7- Clinkstone; which see. 8. Earthy common felspar. This seems to be disentegrated common felspar. 9. Porcelain earth. See CLAY. II. Pyramidal felspar. See SCAPOLITE, and ELAOLITE, III. Prismato-pyramidal felspar. See MEIONITE. IV. Rlioniboidal felspar. SeeNEPHELiNE. Chiastolite and sodalite have also been an- nexed to this species by Professor Jameson. FERMENTATION. When aqueous com- binations of vegetable or animal matter are exposed to ordinary atmospherical tempera- tures, they speedily undergo spontaneous changes, to which the generic name of fer- mentation has been given. Animal liquids alone, or mixed with vegetables, speedily be- come sour. The act which occasion this al- teration is called acetous fermentation, because the product is, generally speaking, acetic acid, or vinegar. But when a moderately strong solution of saccharine matter, or saccharine matter and starch, or sweet juices of fruits, suffer this intestine change, the result is an intoxicating liquid, a beer, or wine ; whence the process is called vinous fermentation. An ulterior change to which all moist animal and vegetable matter is liable, accompanied by the disengagement of a vast quantity of fetid gases, is called the putrefactive fermen- tation. Each of these processes goes on most ra- pidly at a somewhat elevated temperature, such as 80 or 100 Fahr. It is for these reasons that, in tropical countries, animal and vegetable substances are so speedily decom- As the ultimate constituents of vegetable matter are oxygen, hydrogen, and carbon ; and of animal matter, the same three principles with azote, we can readily understand that all the products of fermentation must be merely new compounds of these three or four ultimate constituents. Accordingly, 100 parts of real vinegar, or acetic acid, are resolvable, by MM. Gay Lussac and- Thenard's analysis, into 50-224 carbon -J-4G-9 11 hydrogen and oxygen, as they exist in water, + 2-863 oxygen in excess. In like manner, wines are all resolv- able into the same ultimate components, in proportions somewhat different. The aeriform results of putrefactive fermentation are in like manner found to be, hydrogen, carbon, oxygen, and azote, variously combined, and associated with minute quantities of sulphur and phos- phorus. The residuary matter consists of the same principles, mixed with the saline and earthy parts of animal bodies. Lavoisier was the first philosopher who in- stituted, on right principles, a series of ex- periments to investigate the phenomena of fermentation, and they were so judiciously contrived, and so accurately conducted, as to give results comparable to those derived (rom the more rigid methods of the present day. Since then M. Thenard and M. Gay Lussac have each contributed most important re- searches. By the labours of these three il- lustrious chemists, those material metamor- phoses, formerly quite mysterious, seem sus- ceptible of a satisfactory explanation. 1. Vinous fermentation. As sugar is a substance of uniform and determinate com- position, it has been made choice of for de- termining the changes which arise when its solution is fermented into wine or alcohol. Lavoisier justly regarded it as a true vegetable oxide, and stated its constituents to be, 8 hy- drogen, 28 carbon, and 64 oxygen, in 100 parts. By two different analyses of Berzelius we have, Hydrogen, 6802 6-891 Carbon, 44-115 42-704 Oxygen, 49-083 50-405 100-000 100-000 MM. Gay Lussac and Thenard's analysis gives, Hydrogen, 6-90) - Oxygen, 50-63 j" 7>5d water ' Carbon, 42-47 42-47 ,100-00 100-00 It has been said, that sugar requires to be dissolved in at least 4 parts of water, and to be mixed with some yeast, to cause its fer- mentation to commence. But this is a mis- take. Syrup stronger than the above will ferment in warm weather, without addition. If the temperature be low, the syrup weak, and no yeast added, acetous fermentation alone will take place. To determine the vinous, therefore, we must mix certain proportions of saccharine matter, water, and yeast, and place them in a proper temperature. To observe the chemical changes which occur, we must dissolve 4 or 5 parts of pure sugar in 20 parts of water, put the solution into a matrass, and add 1 part of yeast. Into the mouth of the matrass a glass tube must be luted, which is recurved, so as to dip into the mercury of a pneumatic trough. If the ap- paratus be now placed in a temperature of from 70 to 80, we shall speedily observe the syrup to become muddy, and a multitude of air bubbles to form all around the ferment. These unite, and attaching themselves to particles of the yeast, rise along with it to the surface, forming a stratum of froth. The yeasty matter FER 466 FEE will then disengage itself from the air, fall to the bottom of the vessel, to reaequire buoy- ancy a second time by attached air-bubbles, and thus in succession. If we operate on 3 or 4 ounces of sugar, the fermentation will be very rapid during the first ten or twelve hours ; it will then slacken, and terminate in the course of a few days. At this period the matter being deposited which disturbed the transpa- rency of the liquor, this will become clear. The following changes have now taken place : 1 . The sugar is wholly, and the yeast partially decomposed. 2. A quantity of al- cohol and carbonic acid, together nearly in weight to the sugar, is produced. 3. A white matter is formed, composed of hydrogen, oxygen, and carbon, equivalent to about half the weight of the decomposed ferment. The carbonic acid passes over into the pneumatic apparatus ; the alcohol may be separated from the vinous liquid by distillation, and the white matter falls down to the bottom of the matrass with the remainder of the yeast. The quantity of yeast decomposed is very small. 100 parts of sugar require, for com- plete decomposition, only two and a half of that substance, supposed to be in a dry state. It is hence very probable, that the ferment, which has a strong affinity for oxygen, takes a little of it from the saccharine particles, by a part of its hydrogen and carbon, and thus the equilibrium being broken between the con- stituent principles of the sugar, these so react on each other, as to be transformed into al- cohol and carbonic acid. If we consider the composition of alcohol, we shall find no dif- ficulty in tracing the steps of this transfor- mation. If we take 40 of carbon + 60 of water, or its elements, as the true constituents of sugar, instead of 42.47 + 57-53, and con- vert these weights into volumes, we shall have for the composition of that body, very nearly, by weight, 1st, 1 volume vapour of carbon, =0.416 1 volume vapour of water, = 0.625 or, 1 volume vapour of carbon, 1 ditto hydrogen gas, i volume oxygen; or, multiplying each by 3, 3 volumes vapour of carbon, 3 ditto hydrogen, ditto oxygen. 2d, Let us bear in mind, that alcohol is com- posed of 1 voL olefiant gas = 1 vol. vap. of water = 2 vols. vap. of carb. 2 vols. hydrogen. 1 vol. hydrogen, _ ^ vol. oxygen. 3d, 1 vol. carbonic acid = 1 vol. oxygen -f- 1 vol. vapour of carbon. 4. Neglecting the minute products which the yeast furnishes, in the act of fermentation, let us regard only the alcohol and carbonic acid. We shall then see, on comparing the composition of sugar to that of alcohol, that to transform sugar into alcohol, we must with- draw from it one volume of vapour of carbon, and one volume of oxygen, which form by their union one volume of carbonic acid gas. Finally, let us reduce the volumes into weights, we shall find, that 100 parts of sugar ought to be converted, during fermentation, into 51-55 of alcohol, and 48-45 of carbonic acid. Those who are partial to atomical language will see, that sugar may be represented by Atoms. 3 vol. vap. of carb. = 3 = 2-250 40-00 3 do. hydrogen, = 3 = 0-375 6-66 do. oxygen, = 3 = 3-000 53-33 And alcohol, by 2 vol. carbon, 3 do. hydrogen, do. oxygen, 5-625 99.99 = 2 = 1-500 52-16 = 3 = 0-375 13.04 = 1 = 1-000 34-80 2-875 100-00 And carbonic acid, by 1 vol. oxygen, - - = 2 = 2-00 72-72 1 do. vap. of carb. = 1 = 0-75 27-28 100-00 If, therefore, from the sugar group, we take away one atom of carbon, and two of oxygen, to form the carbonic acid group below, we leave an atomic assemblage for forming al- cohol, as in the middle. For this interesting development of the relation between the ul- timate constituents of sugar on the one hand, and alcohol and carbonic acid on the other, we are indebted to M. Gay Lussac. The following comparison, by the same philosopher, illustrates these metamorphoses : Sulphuric ether is composed of Dens, of vapour. 2 vol. olefiant gas, = 1-94441 _ e> , fio . 1 vol. vap. of wat = 0-6250 J ' And alcohol is composed of 2 vol. olefiant gas, = 1-94441 ^ .j.^o 2 do. vap. of water, = 1-2500 } ' Hence, to convert alcohol into ether, we have only to withdraw from it one-half of its constituent water. Let us now see how far experiment agrees with the theoretic deduction, that 100 parts of sugar, by fermentation, should give birth to 51-55 of absolute alcohol, and 48-45 of car- bonic acid. In Lavoisier's elaborate experi- ment, we find that 100 parts of sugar afforded, Alcohol, - - 57-70 Carbonic acid, 35-34 93-04 Unfortunately, this great chemist has omit- ted to state the specific gravity of his alcohoL If we assume it to have been 0-8293, as assigned for the density of highly rectified al- cohol in the 8th table of the appendix to his Elements, we shall find 100 parts of it to contain, by Lowitz's table, 87.23 of absolute m FER 467 FER alcohol, it' its temperature had been 60. But as 54-5 was the thermometvic point indicated in taking sp. gravities, we must reduce the density from 0-8293 to 0-827- We shall then find H',0 parts of it to consist of 88 of absolute alcohol, and 12 of water. Hence, the 57-7 parts obtained by Lavoisier will become 50' 776 of absolute alcohol, which is a surprising accordance with the theoretical quantity 51-55. But about four parts of the sugar, or l-25th, had not been decomposed. If we add two parts of alcohol for this, we would have a small deviation from theory on the other side. There is no reasonable ground for questioning the accuracy of Lavoisier's experiments on fermentation. Any person who considers the excessive care he has evi- dently bestowed on them, the finished pre- cision of his apparatus, and die complacency with which he compares u the substances sub- mitted to fei mentation, and the products re- sulting from that operation, as forming an algebraic equation," must be convinced that the results are deserving of confidence. M. Thenard, in operating on a solution of 300 parts of sugar, mixed with CO of yeast, at the temperature of 59, has obtained such results as abundantly confirm the previous determination of Lavoisier. The following were the products : Alcohol of 0. 822, 171-5 Carbonic acid, . .' ' 94 -G Nauseous residue, ' .' 12-0 Residual yeast, 40-0 Loss, 318-1 41-9 360-0 The latter two ingredients may be disregarded in the cakulation, as the weight of the yeast is nearly equivalent to their sum. Dividing 171-5 by 3, we have 57-17 for the weight of alcohol of 0-822 from 100 of sugar. In the same way we get 31-53 for the carbonic acid. Now, spirit of wine of 0-822 contains 90 per cent, of absolute alcohol. Whence we find 51-453 for the quantity of absolute alcohol by Thenard's experiment; being a perfect accordance with the theoretical deductions of M. Gay Lussac, made at a sub- sequent period. By M. Lavoisier. Hy M. Thenard. By theory. From 100 sugar. From 100 do. A bs. alco. 50 77C. 5 1 453 5 1 - 55 The coincidence of these three results seems perfectly decisive. In determining the density of absolute al- cohol, M . Gay Lussac had occasion to observe, that when alcohol is mixed with water, the density of the vapour is exactly the mean be- tween the density of the alcoholic vapour and that of the aqueous vapour, notwithstanding the affinity which tends to unite them. An important inference flows from this observa- tion. The experiments of M. de Saussure, as corrected by M. Gay Lussac's theory of vo- lumes, demonstrate, that the absolute alcohol which they employed contains no separable portion of water, but what is essential to the existence of the liquid alcohol. Had any fo- reign water been present, then the specific gravity of the alcoholic vapour would have been proportionally diminished; for the va- pour of water is less dense than that of alcohol, in the ratio of 1 to more than 2 5. But since the sp. gravity of alcoholic vapour is precisely that which would result from the condensed union of two volumes vapour of carbon, three ' volumes of hydrogen, and half a volume of oxygen, it seems absurd to talk of such al- cohol still containing 8-3 per cent, of water. The writer of a long article on brewing, in the supplement to the 5th edition of the Ency- clopaedia Britannica, makes the following re- j marks in discussing M. Thenard's researches on fermentation. " Now, alcohol of the spe- cific gravity 0-822 contains one- tenth of its weight of water, which can be separated from it ; and if we suppose with Saussure, that ab- solute alcohol contains 8-3 per cent- of water, then the products of sugar decomposed by fer- mentation, according to Saussure's (Thenard's he means) experiments, are as follows : Alcohol, -47-7 Carbonic acid, 35-34 Or in 100 parts, Alcohol, Carbonic acid, 83-04 57-44 42- 50 100-00 " This result approaches so nearly to that of Lavoisier, that there is reason to suspect that the coincidence is more than accidental." p. 480. This insinuation against the integrity of one of the first chemists in France calls for re- prehension. But farther, M. Gay Lussac's account of the nature of alcohol and its vapour was published a considerable time before the article brtvcing appeared. Indeed our author copies a considerable part of it, so that the above error is less excusable. The ferment or yeast is a substance which separates under the form of flocculi, more or less viscid, from all the juices and infusions which experience the vinous fermentation. It is commonly procured from the beer manu- factories, and is hence called the barm of beer. It c may be easily dried, and is actually exposed for sale in Paris under the form of a firm but slightly cohesive paste, of a greyish-white colour. This pasty barm left to itself in a close vessel, at a temperature of from 55 to 70, is decomposed, and undergoes in some days the putrid fermentation. Placed in contact, at that temperature, with oxygen in a jar inverted over mercury, it absorbs this gas in some hours, H H 2 FEK 468 FIB and there is produced carbonic acid and a little water. Exposed to a gentle heat, it loses more than two-thirds of its weight, becomes dry, hard, and brittle, and may in this state be preserved for an indefinite time. When it is more highly heated, it experiences a complete decomposition, and furnishes all the products which usually result from the distillation of animal substances. It is insoluble in water and alcohol. Boiling water speedily deprives it of its power of readily exciting fermentation. In fact, if we plunge the solid yeast into water for ten or twelve minutes, and place it afterwards in contact with a saccharine solution, this exhibits no symptom of fermentation for a long period. By that heat, the ferment does not seem to lose any of its constituents, or to acquire others. Its habitudes with acids and alkalis I have not been well investigated. From The- > nard's researches, the fermenting principle in yeast seems to be of a caseous or glutinous nature. It is to the gluten that wheat flour owes its property of making a fermentable dough with water. This flour paste may indeed be re- garded as merely a viscid and elastic tissue of gluten, the interstices of which are filled with starch, albumen, and sugar. We know that it is from the gluten that the dough derives its property of rising on the admixture of leaven. The leaven acting on the sweet prin- ciple of the wheat, gives rise in succession to the vinous and acetous fermentations, and of consequence to alcohol, acetic and carbonic acids. The latter gas tends to fly off, but the gluten resists its disengagement, expands like a membrane, forms a multitude of little cavities, which give lightness and sponginess to the bread. For the want of gluten, the flour of all those grains and roots which con- sist chiefly of starch are not capable of making raised bread, even with the addition of leaven or yeast There does not appear to be any peculiar fermentation to which the name panary should be given. When it is required to preserve fermented liquors in the state produced by the first stage of fermentation, it is usual to put them into casks before the vinous process is completely ended ; and in these closed vessels a change very slowly continues to be made for many months, and perhaps for some years. But if the fermentative process be suffered to proceed in open vessels, more especially if the temperature be raised to 90 degrees, the acetous fermentation comes on. In this, the oxygen of the atmosphere is absorbed ; and the more speedily in proportion as the surfaces of the liquor are often changed by lading it from one vessel to another. The usual method consists in exposing the fermented liquor to the air in open casks, the bunghole of which is covered with a tile to prevent the entrance of the rain. By the absorption of oxygen which takes place, the inflammable spirit becomes converted into an acid. If the liquid be then exposed to distillation, pure vinegar comes over instead of ardent spirit. When the spontaneous decomposition is suffered to proceed beyond the acetous process, the vinegar becomes viscid and foul; air is emitted with an offensive smell ; volatile alkali flies off ; an earthy sediment is deposited ; and the remaining liquid, if any, is mere water. This is the putrefactive process. The fermentation by which certain colouring matters are separated from vegetables, as in the preparation of woad and indigo, is carried much farther, approaching to the putrefactive stage. It is not clearly ascertained what the yeast or ferment performs in this operation. It seems probable, that the fermentative process in considerable masses would be carried on progressively from the surface downwards ; and would, perhaps, be completed in one part before it had perfectly commenced in another^ if the yeast, which is already in a state of fermentation, did not cause the process to begin in every part at once. See BREAD, DISTILLATION, PUTREFACTION, ALCO- HOL, WINE, ACID (ACETIC), VEGETA- BLE KINGDOM. FERROCYANATES. See ACID (FER- ROPRUSSIC). FERROCYANIC ACID. See ACID (FERROPRUSSIC). FERROPRUSSIC ACID, and FER- ROPRUSSIATES. See ACID (FERRO- PRUSSIC). FERRURETTED CHYAZIC ACID. The same as Ferroprussic. FETSTEIN. Elaolite. FIBRIN. A peculiar organic compound found both in vegetables and animals. Vau- quelin discovered it in the juice of the papaw tree. It is a soft solid, of a greasy appearance, insoluble in water, which softens in the air, becoming viscid, brown, and semi-transparent. On hot coals it melts, throws out greasy drops, crackles, and evolves the smoke and odour of roasting meat. Fibrin is procured, however, in its most characteristic state from animal matter. It exists in chyle ; it enters into the composition of blood ; of it, the chief part of muscular flesh is formed ; and hence it may be regarded as the most abundant con- stituent of the soft solids of animals. To obtain it, we may beat blood as it issues from the veins with a bundle of twigs. Fibrin soon attaches itself to each stem, under the form of long reddish filaments, which become colourless by washing them with cold water. It is solid, white, insipid, without smell, denser than water, and incapable of affecting the hue of litmus or violets- When moist it possesses a species of elasticity ; J?y desiccation it becomes yellowish, hard, and brittle. Bv distillation we can extract from it FIB 469 FIL much carbonate of ammonia, some acetate, a fetid brown oil, and gaseous products ; while there remains in the retort a very luminous charcoal, very brilliant, difficult of incinera- tion, which leaves, after combustion, phosphate of Kme, a little phosphate of magnesia, car. bonate of lime, and carbonate of soda. Cold water has no action on fibrin. Treated with boiling water, it is so changed as to lose the property of softening and dissolving in acetic acid. The liquor filtered from it, yields precipitates with infusion of galls, and the residue is white, dry, hard, and of an agreeable taste. When kept for some time in alcohol of 0.810, it gives rise to an adipocerous matter, having a strong and disagreeable odour. This matter remains dissolved in the alcohol, and may be precipitated by water. Ether makes it undergo a similar alteration, but more slowly. When digested in weak muriatic acid, it evolves a little azote, and a compound is formed, hard, horny, and which, washed repeatedly with water, is transformed into another gelatinous compound. This seems to be a neutral muriate, soluble in hot water; whilst the first is an acid muriate, insoluble even in boiling water. Sulphuric acid, diluted with six times its weight of water, has similar effects. When not too concentrated, nitric acid has a very different action on fibrin. For example, when its sp. gr. is 1.25, there results from it at first a disengagement of azote, while the fibrin becomes covered with fat, and the liquid turns yellow. By digestion of 24 hours, the whole fibrin is attacked, and con- verted into a pulverulent mass of lemon- yellow colour, which seems to be composed of a mixture of fat and fibrin, altered and inti- mately combined with the malic and nitric or nitrous acids. In fact, if we put this mass on a filter, and wash it copiously with water, it will part with a portion of its acid, will preserve the property of reddening litmus, and will take an orange hue. On treating it after- wards with boiling alcohol, we dissolve the fatty matter; and putting the remainder in contact with chalk and water, an effervescence will be occasioned by the escape of carbonic acid, and malate or nitrate of lime will remain in solution. Concentrated acetic acid renders fibrin soft at ordinary temperatures, and converts it by the aid of heat into a jelly, which is soluble in hot water, with the disengagement of a small quantity of azote. This solution is colourless, and possesses little taste. Evapo- rated to dryness, it leaves a transparent residue, which reddens litmus paper, and which cannot be dissolved even in boiling water, but by the medium of more acetic acid. Sulphuric, nitric, and muriatic acids, precipitate the animal matter, and form acid combinations. Potash, soda, ammonia, effect likewise the precipitation of this matter, provided we do not use too great an excess of alkali ; for then the precipitated matter would be redissolved. Aqueous potash and soda gradually dissolve fibrin in the cold, without occasioning any perceptible change in its nature; but with heat they decompose it, giving birth to a quantity of ammoniacal gas, and other usual animal products. Fibrin does not putrefy speedily when kept in water. It shrinks on exposure to a considerable heat, and emits the smell of burning horn. It is composed, according to the analysis of MM. Gay Lussac and Thenard, of Carbon, 53.360 Azote, 19.934 Oxygen, 19.685 ) 22.14 water Hydrogen, 7.021 \ 4.56 hydrogen. FIBROLITE. Colours white and grey ; crystallized in rhomboidal prisms, the angles of whose planes are 80 and 100. It is glis- tening internally. Principal fracture uneven. Harder than quartz. Sp. gr. 3.214. Its constituents are alumina 58.25, silica 38, iron and loss 3-75. It is found in the Carnatic. Jameson. FIGURESTONE. See BILDESTEIN. FILTRATION. An operation, by means of which a fluid is mechanically separated from consistent particles merely mixed with it. It does not differ from straining. An apparatus fitted up for this purpose is called a filter. The form of this is various, according to the intention of the operator. A piece of tow, or wool, or cotton, stuffed into the pipe of a funnel, will prevent the passage of grosser particles, and by that means render the fluid clearer which comes through. Sponge is still more effectual. A strip of linen rag wetted and hung over the side of a vessel con- taining a fluid, in such a manner as that one end of the rag may be immersed in the fluid, and the other end may remain without, below the surface, will act as a syphon, and carry over the clearer portion. Linen or woollen stuffs may either be fastened over the mouths of proper vessels, or fixed to a frame, like a sieve, for the purpose of filtering. All these are more commonly used by cooks and apothe- caries than by philosophical chemists, who, for the most part, use the paper called cap paper, made up without size. As the filtration of considerable quantities of fluid could not be effected at once without breaking the filter of paper, it is found requi- site to use a linen cloth, upon which the paper is applied and supported. Precipitates and other pulverulent matters are collected more speedily by filtration than by subsidence. But there are many chemists who disclaim the use of this method, and avail themselves of the latter only, which is certainly more accurate, and liable to no objection, where the powders are such as will admit of edulcoration and drying in the open air. Some fluids, as turbid water, may be puri- FLI 470 FLO fied by filtering through sand. A large earthen funnel, or stone bottle with the bottom beaten out, may have its neck loosely stopped with small stones, over which smaller may be placed, supporting layers of gravel increasing in fineness, and lastly covered to the depth of a few inches with fine sand, all thoroughly cleansed by washing. This apparatus is su- perior to a filtering stone, as it will cleanse water in large quantities, and may readily be renewed when the passage is obstructed, by taking out and washing the upper stratum of sand. A filter for corrosive liquors may be con- % structed, on the same principles, of broken and pounded glass. FIORITE. Pearl Sinter, a volcanic pro- duction, chiefly silica, in a stalactitical form. FIRE. See CALORIC and COMBUSTION. FIRE-DAMP. See COMBUSTION and . CARBU RETTED HYDROGEN. FIREWORKS, Under STRONTIA, will be found a recipe for making the red fire for representing the effect of conflagrations in theatres. The following mixture, when burned before a reflector, sheds a beautiful yreen light upon all surrounding objects. It may also be employed in the changes of fireworks alternating with red and blue fire. Take of Flowers of sulphur 13 parts Nitrate of barytes 77 Chlorate of potash 5 Metallic arsenic 2 Charcoal f 3 100 The materials must be in fine powder, and thoroughly triturated together. FISH-SCALES are composed of alter- nate layers of membrane and phosphate of lime. FIXED AIR. Carbonic acid gas. FIXITY. The property by which bodies resist the action of heat, so as not to rise in vapour. FLAKE-WHITE. Pure carbonate of lead. FLAME. See COMBUSTION. FLESH. The muscles of animals. They consist chiefly of fibrin, with albumen, gelatin, extractive, phosphate of soda, phosphate of ammonia, phosphate and carbonate of lime, and sulphate of potash. See MUSCLE. FLINT. Colour generally grey, with occasionally zoned and striped delineations. Massive, in rolled pieces, tuberose and perfo- rated. It rarely occurs in supposititious, hollow, pyramidal, or prismatic crystals. It occurs often in extraneous shapes, as echi- nites, coralites, madreporites, fungites, be- lemnites, mytilites, &c. ; sometimes in lamel- lar concretions. Internal lustre glimmering. Fracture conchoidal. Fragments sharp-edged. Translucent. Harder than quartz. Easily frangible- Sp. gr. 2-50. Infusible without addition, but whitens and becomes opaque. Its constituents are 98 silica, 0-50 lime, 0-25 alumina, 0-25 oxide of iron, 1-0 loss. When two pieces of flint are rubbed together in the dark they phosphoresce, and emit a peculiar smell. It occurs in primitive, transition, second- ary, and alluvial mountains. In the first two in metalliferous and agate veins. In second- ary countries it is found in pudding-stone, limestone, chalk, and amygdaloid. In chalk it occurs in great abundance in beds. These seem to have been both formed at the same time. Werner, however, is of opinion that the tuberose and many other forms have been produced by infiltration.- In Scotland it occurs imbedded in secondary limestone in the island of Mull, and near Kirkaldy in Fifeshire. In England it abounds in alluvial districts in the form of gravel, or is imbedded in chalk. In Ireland it occurs in considerable quantities in secondary limestone. It is found in most parts of the world. Its principal use is for gun flints, the mechanical operations of which manufacture are fully detailed by Brogniart, The best flint for this purpose is the yellowish- grey. It is an ingredient in pottery, and che- mists use it for mortars. FLINT Y-SL A TE. Of this mineral there are two kinds, common flinty-slate, and Ly~ dian stone. 1. Common. Colour ash-grey, with other colours, in flamed, striped, and spotted deli- neations. It is often traversed by quartz veins. Massive, and in lamellar concretions. Inter- nally it is faintly glimmering. Fracture in the great, slaty; in the small, splintery. Trans- lucent. Hard. Uncommonly difficultly fran- gible. Sp. gr. 2-f>3. It occurs in beds, in clay-slate anil grey-wacke; and in roundish and angular masses in sandstone. It is found in different parts of the great tract of clay- slate and grey-wacke which extends from St. Abb's head to Po/ipatrick ; also in the Pent- land hills near Edinburgh. 2. Lydian stone. Colour greyish-black, which passes into velvet-black. It occurs massive, and rolled in pieces with glistening surfaces. Internally it is glimmering. Frac- ture even. Opaque. Less hard than flint. Difficultly frangible. Sp. gr. 2-C. It occurs very frequently along with common flinty- slate in beds in clay-slate. It is found near Prague and Carlsbad in Bohemia, in Saxony, the Hartz, and at the Moorfoot and Penlland hills near Edinburgh. It is sometimes used as a touchstone for ascertaining the purity of gold and silver. See ASSAY. FLOATS-TONE. A sub-species of the indivisible quartz of Mohs. Spongiform quartz of Jameson. Colour white of various shades. In porous, massive, and tuberose forms. In- ternally it is dull. Fracture coarse, earthy. Feebly translucent on the edges. Soft, but its minute particles are as hard as quart?;. Rather brittle. Easily frangible. Feels mea- FLU 471 FLU gre and rough, and emits a grating noise, when the finger is drawn across it. Sp. gr. 0-49. Its constituents are, silica 98, carbon- ate of lime 2. Vaitq. It occurs incrasting flint, or in imbedded masses in a secondary limestone at St. Ouen near Paris. Jameson. FLOETZ ROCKS. Mineral formations of the secondary kind, composed of strata, for the most part horizontal and parallel to each other. FLOS FERRI. A radiated variety of carbonate of lime, or of calc-spar. FLOUR. The powder of the gramineous seeds. Its use as food is well known. See BREAD. FLOWERS. A general appellation used by the elder chemists to denote all such bodies as have received a pulverulent form by sublimation. FLOWERS OF VEGETABLES. Dr. Lewis, in his notes on Neumann's Chemistry, gives a cursory account of many experiments made with a view to ascertain how far the colour of vegetable flowers might prove of use to the dyer. He found very few capable of being applied to valuable purposes. The flowers of plants convert oxygen into carbonic acid with great rapidity. Thus those of the Passtfl-ora scrratifolia consume of oxy- gen in this way 18^- times their bulk, in 24 hours, when sheltered from the direct rays of the sun, at a temperature between 18and25 C. The male flowers of the cucumber 12 times their bulk; the female only 3^; the single red gilliflower (Chcirairthus Incanus] 11 ; the single tuberose 9, and the typha latifolia 9.8. T. de Saussure Ann. de Chimie, xxi. 279. FLUATES. Compounds of the salifiable bases with fluoric acid. FLUIDITY. The state of bodies when their parts are very readily moveable, in all di- rections with respect to each other. See CALORIC. FLUOBORATES. Compounds of fluo- boric acid with the salifiable bases. FLUOBORIC ACID. See ACID (FLuo- BORIC). FLUOR. Octohedral fluor of Jameson. It is divided into three sub-species ; compact fluor, foliated fluor, and earthy fluor. 1. Compact. Colours, greenish-grey and greenish- white. Massive. Dull or feebly glim- mering. Fracture even. Fragments sharp- edged. Translucent. Harder than calcareous spar, but not so hard as apatite. Brittle, and easily frangible. Sp. gr. 3- 17- It is found in veins, associated with fluor spar, at Stolberg in the Hartz. 2. Foliated. Colours, white, yellow, green, and blue. Green cubes appear with white an- gles. Massive, disseminated, and in distinct concretions. Crystallized in cubes, perfect or variously truncated and bevelled; in the rhomboidal dodecahedron, and the octohedron, or double four-sided pyramid. The crystals are generally placed on one another, and form druses ; but are seldom single. Surface smooth and splendent, or drusy and rough. Internal lustre specular-splendent, or shining vitreous. Cleavage fourfold, equiangular, parallel with the planes of an octohedron. Fragments octo- hedral or tetrahedral. Translucent to transpa- rent. Single refraction. Harder than calcareous spar, but not so hard as apatite. Brittle, and easily frangible. Sp. gr. 3-15. Before the blow- pipe it generally decrepitates, gradually loses its colour and transparency, and melts without addition into a greyish-white glass. When two fragments are rubbed together they become luminous in the dark. When gently heated, it phosphoresces with a blue and green light. By ignition it loses its phosphorescent proper- ty. The violet blue variety from Nertschin- sky, called chlorophane, when placed on glow- ing coals, does not decrepitate, but soon throws out a green light. Sulphuric acid evolves from J pulverized fluor spar acid fumes which corrode \ glass. Its constituents, by Berzelius, are 72-1 lime, and 27-9 fluoric acid. It occurs prin- cipally in veins that traverse primitive, tran- sition, and sometimes secondary rocks. It has been found only in four places in Scotland, near Monaltree in Aberdeenshire, in gneiss in Sun- derland, in secondary porphyry near Gourock in Renfrewshire, and in the island of Papastour one of the Shetlands. It occurs much more abundantly in England, being found in all the galena veins that traverse the coal formation in Cumberland and Durham ; in secondary or floetz limestone in Derbyshire ; and it is the most common veinstone in the copper, tin. and leadlveins, that traverse granite, clay-slate, &c. in Cornwall and Devonshire. It is also fre- quent on the Continent of Europe. It is cut into ornamental forms. It has also been used as a flux for ores ; whence its namejluor. Jameson. 3. Earthy Jluor. Colour, greyish- white and violet-blue, sometimes very deep. It occurs generally in crusts investing some other mi- neral. Dull. Earthy. Friable. Its constituents are the same as the preceding. It occurs in veins along with fluor spar at Beeralstone in Devonshire ; in Cumberland, in Saxony, and Norway. FLUORIC ACID. See ACID (FLUO- RIC). FLUORIDES. Compounds of fluorine with the electro-positive elements, briefly spoken of by M. Dumas in the 31 st volume of the Annales de Chim. et Phys. He obtains these compounds by treating the fluoride (fluate) of mercury or of lead with bodies more posi- tive than these metals. Fluoride of arsenic is a liquid exactly re- sembling the fuming liquor of Libavius, very volatile, heavier than water, becoming in this fluid fluoric and arsenious acids. It scarcely acts on glass ; but immediately disintegrates the skin. FLU 472 FRA Fluoride of antimony is solid at ordinary temperatures, white as snow, more volatile than sulphuric acid, but fcss so than water. Fluoride of phosphorus is a colourless fum- ing liquid, easily obtained in abundance by operating on fluoride of lead with phosphorus. Us composition* corresponds to the proto- chloride of phosphorus. In the same way may be obtained the Fluoride of sulphur. These are compounds of the same kind as those obtained by M. Unverdorben, by treat- ing the chromate of lead with (anhydrous) sulphuric acid, and fluate of lime, or common salt. FLUORINE. The unknown radical of fluoric acid. FLUOSILICATES. See ACID (Fm- OSILICIC). FLUOSILICIC ACID. See ACID (FLU- ORIC). FLUX. A general term made use of to denote any substance or mixture added to assist the fusion of minerals. In the large way, limestone and fusible spar are used as fluxes. The fluxes made use of in assays, or philosophical experiments, consist usually of alkalis, which render the earthy mixtures fusible, by converting them into glass; or else glass itself in powder. Alkaline fluxes are either the crude flux, the white flux, or the black flux. Crude flux is a mixture of nitre and tartar, which is put into the crucible with the mineral intended to be fused. The detonation of the nitre with the inflammable matter of the tartar is of service in some operations ; though generally it is attended with inconvenience on account of the swelling of the materials, which may throw them out of the vessel, if proper care be not taken either to throw in only a little of the mixture at a time, or to provide a large vesstl. White flux is formed by projecting equal parts of a mixture of nitre and tartar, by mo- derate portions at a time, into an ignited cruci- ble. In the detonation which ensues, the ni- tric acid is decomposed, and flies off with the tartaric acid, and the remainder consists of the potash in a state of considerable purity. This has been called fixed nitre. Black flux differs from the preceding, in the proportion of its ingredients. In this, the weight of the tartar is double that of the nitre ; on which account the combustion is incomplete and a considerable portion of the tartaric acid is decomposed by the mere heat, and leaves a quantity of coal behind, on which the black colour depends. It is used where metallic ores are intended to be reduced, and effects this purpose, by combining with the oxygen of the oxide. The advantage of M. Morveau's reducing flux, seems to depend on its containing no ex- cess of alkali. It is made of eight parts of pulverized glass, one of calcined borax, and half a part of powder of charcoal. Care must be taken to use a glass which contains no lead. The white glasses contain in general a large proportion, and the green bottle glasses are not perhaps entirely free from it. See BLOW- PIPE. FORGE FURNACE. The forge furnace consists of a hearth, upon which a fire may be made, and urged by the action of a large pair of double bellows, the nozzle of which is in- serted through a wall or parapet constructed for that purpose. Black lead pots, or small furnaces of every desired form, may be placed, as occasions re- quire, upon the hearth ; and the tube of the bellows being inserted into a hole in the bottom of the furnace, it becomes easy to urge the heat to almost any degree required. FORMATION. In geology, an assem- blage of mineral strata or masses, connected with each other, so as to form one whole or system, without any notable interruption, either in the period or nature of their pro- duction. FORMIATES. Compounds of formic acid with the salitiable bases. FORMIC ACID. See ACID (Fou- MIC). FRACTURE. In mineralogy, the form and aspect of the surface produced by breaking off a piece of a mineral with the hammer. Werner divides the varieties of fracture into compact, fibrous, radiated, and foliated. The compact may be splintery, even, conchoidal, uneven, earthy, or hackly. The fibrous may be coarse or delicate, straight or curved, paral- lel or diverging ; and the diverging again, is either stellular, scopiform, or promiscuous. The radiated fracture is broad or narrow, straight or curved, parallel, diverging, or pro- miscuous ; and streaked or smooth. FREEZING. See CALORIC, and CON- GELATION. FOSSIL COPAL, or Highgate resin. Its colour is pale muddy yellowish-brown. It oc- curs in irregular roundish pieces. Lustre resinous. Semitransparent. Brittle. Yields easily to the knife. Sp. gr. 1-04G, When heated, it gives out a resinous aromatic odour, melts into a limpid fluid, takes fire at a lighted candle, and burns entirely away before the blowpipe. Insoluble in potash ley. Found in the bed of blue clay at Highgate near Lon- don. Alkeii's Mineralogy. FRANKINCENSE. ' See OLIBANUM. FRANKLINITE. A. mineral resembling oxidulous iron. Metallic, black, and mag- netic, but not with polarity. It occurs in grains or in granular masses composed of imperfect crystals. It is not hard ; brittle ; powder, deep red brown; sp. grav. 4.87- It consists of oxide of iron GG, brown oxide of manganese 16, oxide of zinc 17. The regu- lar cctohcclron is its primary form. It occurs FUL 473 FUL in New Jersey, accompanying the red oxide of zinc Phillips' Mineralogy. FRENCH BERRIES. The fruit of the Rhamnns infectorius, called by the French graines d' Avignon. They give a pretty good yellow colour, but void of permanency. When used for dyeing, the cloth is prepared in the same manner as for weld. FRIESLAND GREEN. Ammomaco- muriate of copper, the same with Brunswick green. See COPPER. FRITT. The materials of glass are first mixed together, and then exposed to calcina- tion by a degree of heat not sufficient to melt them. The mass is then called fritt. FRUITS OF VEGETABLES. SAP GREEN is prepared from the berries of buck- thorn, and ANNOTTO is obtained from the pellicles of the seeds of an American tree. See the words. FULIGINOUS. Vapours which possess the property of smoke ; namely, opacity, and the disposition to apply themselves to sur- rounding bodies in the form of a dark co- loured powder. FULLER'S EARTH. Colour greenish- white, and other shades of green. Massive. Dull. Fracture uneven. Opaque. Shining and resinous in the streak. Very soft. Sectile. Scarcely adheres to the tongue. Feels greasy. Sp. gr. 1-7 to 2-2. It falls into a powder with water, without the crackling noise which accompanies the disintegration of bole. It melts into a brown spongy scoria before the blowpipe. Its constituents are, 53 silica, 10 alumina, 1-25 magnesia, 0-50 lime, 0-10 mu- riate of soda, trace of potash, oxide of iron 9-75, water 24 Klaprotli. Bergmann found 24 alumina, and only 0-7 oxide of iron. In England it occurs in beds, sometimes above, sometimes below, the chalk formation; at Rosswein in Upper Saxony, under strata of greenstone slate; and in different places in Germany it is found immediately under the soil. The best is found in Buckinghamshire and Surrey. When good, it has a greenish- white, or greenish-grey colour, falls into powder in water, appears to melt on the tongue like butter, communicates a milky hue to water, anft deposits very little sand when mixed with boiling water. The remark- able detersive property on woollen cloth de- pends on the alumina, which should be at least one-fifth of the whole, but not much more than one-fourth, lest it become too tena- cious. Jameson. FULMINATING and FULM1 NA- TION. In a variety of chemical combina- tions it happens that one or more of the prin- ciples assume the elastic state with such ra- pidity that the stroke against the displaced air produces a loud noise. This is called fulmi- nation, or much more commonly detonation. Fulminating gold, and fulminating powder, are the most common substances of this kind, except gunpowder. For the latter of these see the article GUNPOWDER. The fulminating powder is made by triturating in a warm mor- tar three parts by weight of nitre, two of car- bonate of potash, and one of flowers of sulphur. Its effects, when fused in a ladle, and then set on fire, are very great. The whole of the melted fluid explodes with an intolerable noise, and the ladle is commonly disfigured, as if it had received a strong blow downwards. If a solution of gold be precipitated by ammonia the product will be fulminating gold. Less than a grain of this, held over the flame of a candle, explodes with a very sharp and loud noise. This precipitate, sepa- rated by filtration, and washed, must be dried without heat, as it is liable to explode with no great increase of temperature; and it must not be put into a bottle closed with a glass stopple, as the friction of this would expose the operator to the same danger. Fulminating silver may be made by pre- cipitating a solution of nitrate of silver by lime water, drying the precipitate by exposure to the air for two or three days, and pouring on it liquid ammonia. When it is thus con- verted into a black powder, the liquid must be poured off, and the powder left to dry in the air. It detonates with the gentlest heat, or even with the slightest friction, so that it must not be removed from the vessel in which it is made. If a drop of water fall upon it, the percussion will cause it to explode. It was discovered by Berthollet. Brugnatelli made a fulminating silver by powdering a hundred grains of nitrate of silver, putting the powder into a beer glass, and pouring on it, first an ounce of alcohol, then as much concentrated nitrous acid. The mix- ture grows hot, boils, and an ether is visibly formed, that changes into gas. By degrees the liquor becomes milky and opaque, and is filled with small white clouds. When all the grey powder has taken this form, and the li- quor has acquired a consistency, distilled water must be added immediately to suspend the ebullition, and prevent the matter from being redissolved, and becoming a mere solu- tion of silver. The white precipitate is then to be collected on a filter, and dried. The force of this powder greatly exceeds that of fulminating mercury. It detonates in a tre- mendous manner, on being scarcely touched with a glass tube, the extremity of which has been dipped in concentrated sulphuric acid. A single grain, placed on a lighted coal, makes a deafening report. ' The same thing happens if it be placed on a bit of paper on an electric pile, and a spark drawn from it. Fulminating mercury was discovered by Mr. Howard. A hundred grains are to be dissolved with heat in an ounce and half by measure of nitric acid. The solution, when cold, is to be poured on two ounce measures of alcohol, and heat applied till an efFer- FUM 474 FUS vescence is excited. As soon as the precipitate is thrown down, it must be collected on a filter, that the acid may not react on it; washed, and dried by a very gentle heat. It detonates with a very little heat or friction. Three parts of chlorate of potash, and one of sulphur, triturated in a metal mortar, cause numerous successive detonations, like the cracks of a whip, the reports of a pistol, or the fire of musketry, according to the rapidity and force of the pressure employed. A few grains, struck with a hammer on an anvil, explode with a noise like that of a musket, and tor- rents of purple light appear round it. Thrown into concentrated sulphuric acid, it takes fire and burns with a white flame, but without noise. Six parts of the chlorate, one of sulphur, and one of charcoal, detonate by the same means, but more strongly, and with a redder flame. Sugar, gum, or charcoal, mixed with the chlorate, and fixed or volatile oils, alcohol, or ether, made into a paste with it, detonate very strongly by the stroke, but not by trituration. Some of them take fire, but slowly, and by degrees, in the sulphuric acid. All those mixtures that detonate by the stroke, explode much more loudly if previously wrapped up in double paper. Fulminations of the most violent kind re- quire the agency of azote or nitrogen ; as we see not only in its compounds with the oxides of gold, silver, and platina; but still more remarkably in its chloride and iodide. See NITROGEN and ANTIMONY. FUMIGATIONS, to destroy contagious miasmata or effluvia. The most efficacious substance for this purpose is chlorine ; next to it the vapour of nitric acid ; and lastly, that of the muriatic. The fumes of heated vinegar, burning sulphur, or the smoke of exploded gunpowder, deserve little confidence as anti- loimics. The air of dissecting rooms should be nightly fumigated with chlorine, whereby their atmosphere would be more wholesome and agreeable during the day. Mr. Faraday having been employed to fumigate the General Penitentiary at Milbank, used the following method : One part by weight of common salt was well mixed with one part of black oxide of manganese. On this mixture, placed in a shallow earthen pan, 2 parts of oil of vitriol previously diluted with one part by weight (or about 2 parts by bulk) of water, and left till cold, were poured. Such a mixture, stirred with a stick, and made at 60 F. began in a few minutes to liberate chlorine, and continued to do so for four days. The whole quantity of materials used was 700lb. of common salt, 700 of manganese, and 1400 of oil of vitriol. The space requiring fumigation amounted to nearly 2,000,000 cubic feet; and the surface of the walls, floors, cielings, &c. exclusive of furniture, bedding, &c. was about 1.200,000 square feet. This surface was principally stone and brick, most of which had been lime-washed. Mr. Faraday remarks, that probably much less chlorine would have been sufficient. Journal of Science, xviii. 92. FUMING LIQUOR. The fuming liquors of Boyle and Libavius have been long known. To prepare that of Boyle, which is a hydro- guretted sulphuret of ammonia, three parts of lime fallen to powder in the air, one of muriate of ammonia, and one of flowers of sulphur, are to be mixed in a mortar, and distilled with a gentle heat. The yellow liquor, that first comes over, emits fetid fumes. It is followed by a deeper coloured fluid, that is not fuming. The fuming liquor of Libavius is made by amalgamating tin with half its weight of mercury, triturating this amalgam with ah. equal weight of corrosive muriate of mercury, and distilling by a gentle heat. A colourless fluid at first passes over : after this, a thick vapour is thrown out at one single jet with a sort of explosion, which condenses into a transparent liquor, that emits copious, white, heavy, acrid fumes, on exposure to the air. In a closely stopped bottle, no fumes from it are perceptible; but needle-shaped crystals form against the top of the bottle, so as fre- quently to close the aperture. Cadet's fuming liquor is prepared by dis- tilling equal parts of acetate of potash and arsenious acid, and receiving the product into glass bodies, kept cool by a mixture of ice and salt. The liquor produced, emits a very dense, heavy, fetid, noxious vapour, and inflames spontaneously in the open air. FUNGATES. The saline compounds of a peculiar acid, which M. Braconnot has lately extracted from mushrooms. FUNGIN. The fleshy part of mushrooms, deprived by alcohol and water of every thing soluble. It seems to be a modification of woody fibre. FURNACE. See LAB ORATORY. FUSCITE. A greyish or greenish-black opaque mineral. It crystallizes in prisms. Sp. grav. 2.5 3. It is found at Kallingeren, near Arendahl in Norway, in rolled masses of granular quartz. FUSIBLE METAL. See ALLOY. A combination of 3 parts of lead, with 2 of tin and 5 of bismuth, melts at 197 F. FUSIBILITY. That property by which bodies assume the fluid state. Some chemists have asserted that fusion is simply a solution in caloric; but this opinion includes too many yet undecided questions, to be hastily adopted. GAD 475 GAD Fusibility of Metals, as given by M. Thenard. 1. Fusible below a red heat. 2. Infusible below a red heat. Mercury, Center. 39 Potassium, Sodium, ')L > Gay Lussac and Thenard. Tin, Bismuth, 25G \ Ncwton " Lead, 2GO Biot. Tellurium, A little less fusible than lead Klaproth. Arsenic, Undetermined. Zinc, 370 Brogniart. Antimony, A little below a red heat. Cadmium, Stromeycr. Pyrometer of Wedgewood. Silver, 20 Kennedy. sr 32 } Wedgewood. Cobalt, A little less difficult to melt than iron. T S 130 Wedgewood. JLron^ * 158 Sir G. M'Kenzie. Manganese, 160 Guy ton. Nickel, As manganese. Richter. Palladium Molybdenum, "V Uranium, Tungsten, Chromium, f Nearly infusible ; and to be obtained at a forge / heat, only in small buttons. Titanium, 1 Cerium, Osmium, j Infusible at the forge furnace. Fusible at Indium, ) the oxyhydrogen blowpipe. See BLOW- Rhodium, PIPE. Platinum, J Columbium, J FUSION. The act of fusing. Also the state of a fused body. FI T STET. The wood of the rhus cotinns, or Venus's sumach, yields a fine orange colour, but not at all durable. FUSTIC, OR YELLOW WOOD. This wood, the morns t'tnctorla^ is a native of the West Indies. It affords much yellow colouring matter, which is very permanent. The yellow given by the fustic without any mordant is dull, and brownish, but stands welL The mordants employed with weld act on it in a similar manner, and by their means the colour is rendered more bright and fixed. The difference between them is, that the yellow of fustic inclines more to orange than that of weld ; and, as it abounds more in colouring matter, a less quantity will suffice. G GABBRO. The name given by the Italian artists, and by M. de Buch, to a rock essentially composed of felspar and diallage, called by the French geologists EUPHOTIDE, which see. GABBRONIT. Scapolite. GADOLINITE. Prismatic gadolinite. Molts. Its colours are velvet-black, and black of various shades. Massive and disseminated. Rarely crystallized. Its primitive figure seems to be an oblique four-sided prism, in which prism Janes. the obtuse angle is nearly 110. This sometimes occurs with six lateral plants. Lustre resinous inclining to vitreous. Fracture conchaidal. Very faintly translucent on the thinnest edges, and then it appears blackish- green. Harder than felspar, but softer than quartz. Streak greenish-grey. Brittle ; dif- ficultly frangible. When pure it does not affect the magnet. Sp. gr. 4.0 to 4.2. It intumesces very much before the blowpipe, and at length melts into an imperfect slag, which is magnettcal. It loses its colour in GAL 476 GAL nitric acid, and gelatinizes. Its constituents are 25.8 silica, 45 yttria, 16.C9 oxide of cerium, 10.26 oxide of iron, 0.60 volatile matter Berzelius. It occurs along with yttrotantalite at Ytterby in Sweden, in beds of a coarse granular red felspar, which are situated in mica slate; at Finbo, near Fahlun, also in Sweden, in a coarse granular granite, along with pyrophysalite and tin-stone.- Jameson. GAHNITE. Automalite or octohedral corundum. GALLITZINITE. Rutile. An ore of titanium. GALBANUM exudes from the bubon galbanum. This juice comes over in masses, composed of white, yellowish, brownish- yellow, and brown tears, unctuous to the touch, softening betwixt the fingers ; of a bitterish, somewhat acrid, disagreeable taste, and a very strong smell; generally full of bits of stalks, leaves, seeds, and other foreign matters. Galbanum contains more of a resinous than gummy matter ; one pound yields with alcohol upward of nine ounces and a half of resinous extract ; but the gummy extract obtained by water from the same quantity, amounts only to about three ounces. The resin is hard, brittle, insipid, and inodorous: the gummy extract has somewhat of a nauseous relish ; but could not be distinguished to be a preparation of galbanum. The whole smell, flavour, and specific taste of this juice, reside in an essential oil, which rises in distillation both with water and spirit, and gives a strong impregnation to both : from a pound of galbanum are obtained, by distillation with water, six drachms of actual oil, besides what is retained by the water. In this respect galbanum agrees with asafcetida, and differs from ammoniacum. GALENA. Native sulphuret of lead. See ORES of lead. GALL OF ANIMALS. See BILE. GALL-STONES. Calculous concretions are not unfrequently formed in the gall blad- der, and sometimes occasion great pain in their passage through the ducts into the duodenum, before they are evacuated. Of these stones there are four different kinds. 1. The first has a white colour, and when broken presents crystalline plates, or strias, brilliant and white like mica, and having a soft greasy feel. Sometimes its colour is yellow or greenish; and it has constantly a nucleus of inspissated bile. Its sp. gravity is inferior to that of water : Gren found the specific gravity of one 0.803. When exposed to a heat considerably greater than that of boiling water, this crystallized calculus softens and melts, and crystallizes again when the tem- perature is lowered. It is altogether insoluble in water; but hot alcohol dissolves it with facility. Alcohol, of the temperature of 167, dissolves one-twentieth of its weight of this substance ; but alcohol, at the temperature of 60, scarcely dissolves any of it. As the alco- hol cools, the matter is deposited in brilliant plates, resembling talc or boracic acid. It is soluble in oil of turpentine. When melted, it has the appearance of oil, and exhales the smell of melted wax ; when suddenly heated, it evaporates altogether in a thick smoke. It is soluble in pure alkalis, and the solution has all the properties of a soap. Nitric acid also dissolves it ; but it is precipitated unaltered by water. This matter, which is evidently the same with the crystals Cadet obtained from bile, and which he considered as analogous to sugar of milk, has a strong resemblance to sperma- ceti. Like that substance, it is of an oily nature, and inflammable ; but it differs from it in a variety of particulars. Since it is con- tained in bile, it is not difficult to see how it may crystallize in the gall-bladder, if it hap- pen to be more abundant than usual; and the consequence must be a gall-stone of this species. Fourcroy found a quantity of the same substance in the dried human liver. He called it adipocere. 2. The second species of biliary calculus is of a round or polygonal shape, often of a n colour externally, and brown within. ( formed of concentric layers of a matter which seems to be inspissated bile ; and there is usually a nucleus of the white crystalline matter at the centre. For the most part, there are many of this species of calculus in the gall-bladder together ; indeed it is frequently filled with them. The calculi belonging to this species are often light and friable, and of a brownish-red colour. The gall-stones of oxen used by painters belong to this species. These are also adipocere. 3. The third species of calculi are most numerous of all. Their colour is often deep brown or green ; and when broken, a number of crystals of the substance resembling sper- maceti are observable, mixed with inspissated bile. The calculi belonging to these three species are soluble in alkalis, in soap ley, in alcohol, and in oils. 4. Concerning the fourth species of gall- stone, very little is known with accuracy. Dr. Saunders tells us, that he has met with some gall-stones insoluble both in alcohol and oil of turpentine ; some of which do not flame, but become red, and consume to ashes like charcoal. Haller quotes several examples of similar calculi. Gall-stones often occur in the inferior animals, particularly in cows and hogs; but the biliary concretions of these animals have not hitherto been examined with much attention. Soaps have been proposed as solvents for these calculi. The academy of Dijon has published the success of a mixture of essence of turpentine and ether. See CHOLESTERINE. GAL 477 GAL GALL OF GLASS. Glass gall, called also Sandiver. The salt skimmed off the surface of glass while in fusion. GALLS. These are the protuberances produced by the puncture of an insect on plants and trees of different kinds. Some of them are hard, and termed nut-galls ; others are soft and spongy, and called berry-galls, or apple-galls. The best are the nut-galls of the oak, and those brought from Aleppo are preferred. These are not smooth on the sur- face, but tubercular, small, and heavy ; and should have a bluish or blackish tinge. Deyeux investigated the properties of galls with considerable care ; and more lately Sir H. Davy has examined the same subject The strongest infusion Sir H. Davy could obtain at 56 F. by repeated infusion of dis- tilled water, on the best Aleppo galls, broken into small pieces, was of the specific gravity of 1.068. Four hundred grains of this infusion, evaporated at a heat below 200, left 53 of solid matter, which consisted of about 0.9 tannin, and 0-1 gallic acid, united to apportion of extractive matter. One hundred grains of the solid matter left, by incineration, nearly 4f , which were chiefly calcareous matter, mixed with a small portion of fixed alkali. From 500 grains of Aleppo galls Sir H. Davy obtained, by infusion as above, 185 grains of solid matter, which on analysis ap- peared to consist of tannin 130 ; mucilage, and matter rendered insoluble by evaporation, 1 2 ; gallic acid, with a little extractive matter, 31 ; remainder, calcareous earth and saline matter, 12. The use of galls in dyeing is very extensive, and they are one of the principal ingredients in making ink. Powdered galls made into an ointment with hog's lard are a very efficacious application in piles. They are sometimes given internally as an astringent ; and in the inter- mittents, where the bark has failed. The tu- bercles, or knots, on the roots of young oaks, are said to possess the same properties as the nut-galls, and to be produced in a similar manner. For their acid, see ACID (GALLIC). GALVANISM. The following article is chiefly extracted from a paper, which was read by me at the Glasgow Literary Society, De- cember 10, 1818, and published in the Journal of Science and the Arts of the following Ja- nuary. I have now subjoined a few further observations, on the application of voltaic electricity to the resuscitation of the suspended functions of life. Convulsions accidentally observed in the limbs of dead frogs originally suggested to Galvani the study of certain phenomena, which from him have been styled Galvanic. He ascribed these movements to an electrical fluid or power, innate in the living frame, or capable of being evolved by it, which he de- nominated animal electricity. The Torpedo* Gymnotus, and Silurus Electricus, fish en- dowed with a true electrical apparatus, ready to be called into action by an effort of their will, were previously known to the naturalist, and furnished plausible analogies to the phi- losopher of Bologna. Volta, to whom this science is indebted for the most brilliant dis- coveries on its principles, as well as for its marvellous apparatus, justly called by his name, advanced powerful arguments against the hypothesis of Galvani. He ascribed the muscular commotions, and other phenomena, to the excitation of common electricity, by ar- rangements previously unthought of by the scientific world ; merely by the mutual contact of dissimilar bodies, metals, charcoal, and animal matter, applied either to each other, or conjoined with certain fluids. And at the present day, perhaps the only facts which seem difficult to reconcile with the beautiful theory of electromotion, invented by the Pavian pro- fessor, are some experiments of Aldini, the nephew of the original discoverer. In these experiments, neither metals nor charcoal were employed. Very powerful mus- cular contractions seem to have been excited, in some of the experiments, by bringing a part of a warm-blooded, and of a cold-blooded animal, into contact with each other ; as the nerve and muscle of a frog, with the bloody flesh of the neck of a newly decapitated ox. In other experiments, the nerves and muscles of the same animal seem to have operated Gal- vanic excitation ; and again, the nerve of one animal acted with the muscle of another. He deduces from his experiments an inference in favour of his uncle's hypothesis, that a proper animal electricity is inherent in the body, which does not require the assistance of any external agent for its development. Should we admit the reality of these results, we may perhaps ven- ture to refer them to a principle analogous to Sir H. Davy's pile, or voltaic circuit, of two dissi- milar liquids and charcoal. This part of the subject is however involved in deep obscurity. Many experiments have been performed, in this country and abroad, on the bodies of cri- minals, soon after their execution. Vassali, Julio, and Rossi, made an ample set, on se- veral bodies decapitated at Turin. They paid particular attention to the effect of galvanic electricity on the heart, and other involuntary muscles: a subject of much previous con- troversy. Volta asserted, that these muscles are not at all sensible to this electric power. Fowler maintained, that they were affected ; but with difficulty and in a slight degree. This opinjon was confirmed by Vassali ; who further showed, that the muscles of the sto- mach, and intestines, might thus also be ex- cited. Aldini, on the contrary, declared, that he could not affect the heart by his most powerful galvanic arrangements. GAL 478 GAL Most -of the above experiments were however made, either without a voltaic battery, or with piles, feeble in comparison with those now em- ployed. Those indeed performed on the body of a criminal, at Newgate, in which the limbs were violently agitated ; the eyes opened and shut; the mouth and jaws worked about, and the whole face thrown into frightful con- vulsions, were made by Aldini, with, I believe, a considerable series of voltaic plates. A circumstance of the first moment, in my opinion, has been too much overlooked in experiments of this kind, that a muscular mass through which the galvanic energy is directly transmitted, exhibits very weak con- tractile movements, in comparison with those which can be excited by passing the influence along the principal nerve of the muscle. In- attention to this important distinction, I con- ceive to be the principal source of the slender \ effects hitherto produced in such experiments ^ on the heart, and other muscles, independent of the will. It ought also to be observed, that too little distinction has been made between the positive and negative poles of the battery; though there are good reasons for supposing, that their powers on muscular contraction are by no means the same. According to Hitter, the electricity of the positive pole augments, while the negative diminishes the actions of life. Tumefaction of parts is produced by the former ; depression by the latter. The pulse of the hand, he says, held a few minutes in contact with the posi- tive pole, is strengthened ; that of the one in contact with the negative is enfeebled ; the former is accompanied with a sense of heat ; the latter with a feeling of coldness. Objects appear to a positively electrified eye, larger, brighter, and red; while to one negatively electrified, they seem smaller, less distinct, and bluish, colours indicating opposite ex- tremities of the prismatic spectrum. The acid and alkaline tastes, when the tongue is acted on hi succession by the two electricities, are well known, and have been ingeniously ac- counted for by Sir H. Davy, in his admirable Bakerian Lectures. The smell of oxymuriatic .acid, and of ammonia, are said by Ritter, to be the opposite odours, excited by the two opposite poles ; as a full body of sound and a sharp tone are the corresponding effects on the ears. These experiments require verification. Consonant in some respects, though not in all, with these statements, are the doctrines taught by a London practitioner, experienced in the administration of medical electricity. He affirms, that the influence of the electrical fluid of our common machines in the cure of disease, may be referred to three distinct heads ; first, the form of radii, when projected from a point positively electrified ; secondly, that of a star, or the negative fire, concentred on a brass ball ; thirdly, the Leyden explosion. To each of these fonns he assigns a specific action. The first acts as a sedative, allaying morbid activity ; the second as a stimulant ; and the last has a deobstruent operation, in dispersing chronic tumours. An ample nar- rative of cases is given in confirmation of these general propositions. My own experience leads me to suppose, that the negative pole of a voltaie battery gives more poignant sensa- tions than the positive. But, unquestionably, the most precise and interesting researches on the relation between voltaic electricity and the phenomena of life, are those contained in Dr. Wilson Philip's Dissertations in the Philosophical Transac- tions, as well as in his Experimental Inquiry into the Laws of the Vital Functions, more recently published. In his earlier researches he endeavoured to prove, that the circulation of the blood, and the action of the involuntary muscles, were in- dependent of the nervous influence. In a late paper, read in January 1816, he showed the immediate dependence of the secretory func- tions on the nervous influence. The eighth pair of nerves distributed to the stomach, and subservient to digestion, were divided by incisions in the necks of several living rabbits. After the operation, the parsley which they ate remained without alteration in their stomachs ; and the animals, after evin- cing much difficulty of breathing, seemed to die of suffocation. But when in other rabbits, similarly treated, the galvanic power was transmitted along the nerve, below its section, to a disc of silver, placed closely in contact with the skin of the animal, opposite to its stomach, DO difficulty of breathing occurred. The voltaic action being kept up for twenty -six hours, the rabbits were then killed, and the parsley was found in as perfectly digested a state, as that in healthy rabbits fed at the same tune; and their stomachs evolved the smell peculiar to that of a rabbit during digestion. These experiments were several times repeated with similar results. Hence it appears that the galvanic energy is capable of supplying the place of the nerv- ous influence, so that, while under it, the stomach, otherwise inactive, digests food as usual. I am not, however, willing to adopt the conclusion drawn by its ingenious author, that the " identity of galvanic electricity and nervous influence is established by these expe- riments." They clearly show a remarkable analogy between these two powers, since the one may serve as a substitute for the other. It might possibly be urged by the anatomist, that as the stomach is supplied by twigs of other nerves, which communicate under the place of Dr. Philip's section of the par vttguni, the galvanic fluid may operate merely as a powerful stimulus, exciting those slender twigs to perform such an increase of action, as may GAL 479 GAL Compensate for the want of the principal nerve. The above experiments were repeated on dogs, with like results ; the battery never being so strong as to occasion painful shocks. The removal of dyspnoea, as stated above, led him to try galvanism as a remedy in asthma. By transmitting its influence from the nape of the neck to the pit of the stomach, he gave decided relief in every one of twenty- two cases, of which four were in private prac- tice, and eighteen in the Worcester Infirmary. The power employed varied from ten to twenty- five pairs. The general inferences deduced by him from his multiplied experiments are, that voltaic electricity is capable of effecting the formation of the secreted fluids when applied to the blood in the same way in which the nervous influence is applied to it ; and that it is capable of occa- sioning an evolution of caloric from arterial blood. When the lungs are deprived of the nervous influence, by which their function is impeded, and even destroyed, when digestion is interrupted, by withdrawing this influence from the stomach, these two vital functions are renewed by exposing them to the influence of a galvanic trough. " Hence," says he, " gal- vanism seems capable of performing all the functions of the nervous influence in the animal economy ; but obviously it cannot excite the functions of animal life, unless when acting on parts endowed with the living principle." These results of Dr. Philip have been recently confirmed by Dr. Clarke Abel, of Brighton, who employed, in one of the repeti- tions of the experiments, a comparatively small, and in the other a considerable degree of gal- vanism. In the former, although the galvan- ism was not of sufficient power to occasion evi- dent digestion of the food, yet the efforts to vomit, and the difficulty of breathing, constant effects of dividing the eighth pair of nerves, were prevented by it. These symptoms recur- red when it was discontinued, and vanished on its reapplication. " The respiration of the animal," he observes, " continued quite free during the experiment, except when the dis- engagement of the nerves from the tin-foil rendered a short suspension of the galvanism necessary during their readjustment." "The non-galvanized rabbit breathed with difficulty, wheezed audibly, and made frequent attempts to vomit." In the latter experiment, in which the greater power of galvanism was employed, digestion went on as in Dr. Philip's experi- ments. Jour. Sc. ix. M. Gallois, an eminent French physiologist, had endeavoured to prove that the motion of the heart depends entirely upon the spinal marrow, and immediately ceases when the spinal marrow is removed or destroyed. Dr. Philip appears to have refuted this notion by the following experiments. Rabbits were rendered insensible by a blow on the occiput ; the spinal marrow and brain were then re- moved, and the respiration kept up by arti- ficial means ; the motion of the heart, and the circulation, were carried on as usual. When spirit of wine, or opium, was applied to the spinal marrow or brain, the rate of the circula- tion was accelerated. These general physiological views will serve, I hope, as no tnappropiate introduction to the detail of the galvanic phenomena exhibited here, on the 4th of November, in the body of the murderer Clydesdale ; and they may pro- bably guide us to some valuable practical in- ferences. The subject of these experiments was a middle-sized, athletic, and extremely muscular man, about thirty years of age. He was sus- pended from the gallows nearly an hour, and made no convulsive struggle after he dropped ; while a thief, executed along with him, was violently agitated for a considerable time. He was brought to the anatomical theatre of our university in about ten minutes after he was cut down. His face had a perfectly natural aspect, being neither livid nor tumefied ; and there was no dislocation of his neck. Dr. Jeffray, the distinguished professor of anatomy, having on the preceding day request- ed me to perform the galvanic experiments, I sent to his theatre with this view, next morn- ing, my minor voltaic battery, consisting of 270 "pairs of four inch plates, with wires of communication, and pointed metallic rods with insulating handles, for the more commodious application of the electric power. About five minutes before the police officers arrived with the body, the battery was charged with a dilute mtro-sulphuric acid, which speedily brought it into a state of intense action. The dissec- tions were skilfully executed by Mr. Marshall, under the superintendence of the professor. Exp. 1. A large incision was made into the nape of the neck, close below the occiput. The posterior half of the atlas vertebra was then removed by bone forceps, when the spi- nal marrow was brought into view. A pro- fuse flow of liquid blood gushed from the wound, inundating the floor. A considerable incision was at the same time made in the left hip, through the great gluteal muscle, so as to bring the sciatic nerve into sight; and a small cut was made in the heel. From neither of these did any blood flow. The pointed rod connected with one end of the battery was now placed in contact with the spinal marrow, while the other rod was applied to the sciatic nerve. Every muscle of the body was imme- diately agitated with convulsive movements, resembling a violent shuddering from cold. The left side was most powerfully convulsed at each renewal of the electric contact On moving the second rod from the hip to the heel, the knee being previously bent, the leg was thrown out with such violence as nearly to overturn one of the assistants, who in vain attempted to prevent its extension. GAL 430 GAL Exp. 2. The left phrenic nerve was now laid bare at the outer edge of the stcrnothy- roldcus muscle, from three to four inches above the clavicle; the cutaneous incision having been made by the side of the sternocleido- mastoideus. Since this nerve is distributed to the diaphragm, and since it communicates with the heart through the eighth pah-, it was expected, by transmitting the galvanic power along it, that the respiratory process would be renewed. Accordingly, a small incision hav- ing been made under the cartilage of the seventh rib, the point of the one insulating rod was brought into contact with the great head of the diaphragm, while the other point was applied to the phrenic nerve in the neck. This muscle, the main agent of respiration, was instantly contracted, but with less force than was expected. Satisfied, from ample experience on the living body, that more powerful effects can be produced in galvanic excitation, by leaving the extreme communi- cating rods in close contact with the parts to be operated on, while the electric chain or circuit is completed by running the end of the wires along the top of the plates in the last trough of either pole, the other wire being steadily im- mersed in the last cell of the opposite pole, I had immediate recourse to this method. The success of it was truly wonderful. Full, nay, laborious breathing, instantly commenced. The chest heaved, and fell; the belly was protruded, and again collapsed, with the re- laxing and retiring diaphragm. This process was continued, without interruption, as long as I continued the electric discharges. In the judgment of many scientific gentle- men who witnessed the scene, this respiratory experiment was perhaps the most striking ever made with a philosophical apparatus. Let it also be remembered, that for full half an hour before this period, the body had been well nigh drained of its blood, and the spinal marrow severely lacerated. No pulsation could be perceived meanwhile at the heart or wrist; but it may be supposed, that but for the eva- cuation of the blood, the essential stimulus of that organ, this phenomenon might also have occurred. Exp. 3. The supra-orbital nerve was laid bare in the forehead, as it issues through the supra-ciliary foramen, in the eyebrow : the one conducting rod being applied to it, and the other to the heel, most extraordinary gri- maces were exhibited every time that the electric discharges were made, by running the wire in my hand along the edges of the last trough, from the 220th to the 270th pair of plates : thus fifty shocks, each greater than the preceding one, were given in two seconds. Every muscle in his countenance was simul- taneously thrown into fearful action; rage, horror, despair, anguish, and ghastly smiles, united their hideous expression in the mur- derer's face, surpassing far the wildest repre- sentations of a Fuseli or a Kean. At this pe- riod several of the spectators were forced to leave the apartment from terror or sickness, and one gentleman fainted. Exp. 4. The last galvanic experiment con- sisted in transmitting the electric power from the spinal marrow to the ulnar nerve, as it passes by the internal condyle at the elbow : the fingers now moved nimbly, like those of a violin performer ; an assistant, who tried to close the fist, found the hand to open forcibly, in spite of his efforts. When the one rod was applied to a slight incision in the tip of the fore-finger, the fist being previously clenched, that finger extended instantly ; and from the convulsive agitation of the arm, he seemed to point to the different spectators, some of whom thought he had come to life. About an hour was spent in these operations. In deliberating on the above galvanic phe- nomena, we are almost willing to imagine, that if, without cutting into and wounding the spinal marrow and blood-vessels in the neck, the pulmonary organs had been set a-playing at first, (as I proposed), by electrifying the phrenic nerve, (which may be done without any dangerous incision), there is a probability that life might have been restored. This event, however little desirable with a murderer, and perhaps contrary to law, would yet have been pardonable in one instance, as it would have been highly honourable and useful to science. From the accurate experiments of Dr. Philip it ap- pears, that the action of the diaphragm and lungs is indispensable towards restoring the suspended action of the heart and great vessels, subservient to the circulation of the blood. It is known, that cases of death-like lethargy, or suspended animation, from disease and ac- cidents, have occurred, where life has returned, after longer interruption of its functions than in the subject of the preceding experiments. It is probable, when apparent death supervenes from suffocation with noxious gases, &c. and when there is no organic Isesion, that a judi- ciously directed galvanic experiment will, if any thing will, restore the activity of the vital functions. The plans of administering voltaic electricity hitherto pursued in such cases are, in my humble apprehension, very defective. No advantage, we perceive, is likely to accrue from passing electric discharges across the chest, directly through the heart and lungs. On the principles so well developed by Dr. Philip, and now illustrated on Clydesdale's body, we should transmit along the channel of the nerves, that substitute for nervous influence, or that power which may perchance awaken its dormant faculties. Then, indeed, fair hopes may be formed of deriving extensive benefit from galvanism ; and of raising this wonderful agent to its expected rank among the ministers of health and life to man. I would, however, beg leave to suggest another nervous channel, which I conceive to GAL 481 GAL be a still readier and more powerful one, to the action of the heart and lungs, than the phrenic nerve. If a longitudinal incision be made, as is frequently done for aneurism, through the integuments of the neck at the outer edge of the sterno-mastoideus muscle, about half way be- tween the clavicle and angle of the lower jaw ; then on turning over the edge of this muscle, we bring into view the throbbing carotid, on the outside of which, the par vagum, and great sympathetic nerve, lie together in one sheath. Here, therefore, they may both be directly touched and pressed by a blunt me- tallic conductor. These nerves communicate directly, or indirectly, with the phrenic ; and the superficial nerve of the heart is sent off from the sympathetic. Should, however, the phrenic nerve be taken, that of the left side is the preferable of the two. From the position of the heart, the left phrenic differs a little in its course from the right. It passes over the pericardium, covering the apex of the heart. While the point of one metallic conductor is applied to the nervous cords above de- scribed, the other knob ought to be firmly pressed against the side of the person, imme- diately under the cartilage of the seventh rib. The skin should be moistened with a solution of common salt, or what is better, a hot sa- turated solution of sal ammoniac, by which means, the electric energy will be more effec- tually conveyed through the cuticle so as to complete the voltaic chain. To lay bare the nerves above described, re- quires, as I have stated, no formidable incision, nor does it demand more anatomical skill, or surgical dexterity, than every practitioner of the healing art ought to possess. We should always bear in mind, that the subject of expe- riment is at least insensible to pain ; and that life is at stake, perhaps irrecoverably gone. And assuredly, if we place the risk and dif- ficulty of the operation in competition with the blessings and glory consequent on success, they will weigh as nothing, with the intelli- gent and humane. It is possible, indeed, that two small brass knobs, covered with cloth moistened with solution of sal ammoniac, pressed above and below, on the place of the nerve, and the diaphragmatic region, may suf- fice, without any surgical operation : It may first be tried. Immersion of the body in cold water acce- lerates greatly the extinction of life arising from suffocation ; and hence less hope need be entertained of recovering drowned persons after a considerable interval, than when the vital heat has been suffered to continue with little abatement. None of the ordinary prac- tices judiciously enjoined by the Humane So- ciety should ever on such occasions be ne- glected. For it is surely culpable to spare any pains which may contribute, in the slightest degree, to recall the fleeting breath of man to its cherished mansion. My attention has been again particularly directed to this interesting subject, by a very flattering letter which I lately received from the learned Secretary of the Royal Humane Society. In the preceding account, I had accidentally omitted to state a very essential circumstance relative to the electrization of Clydesdale. The paper indeed was very rapidly written, at the busiest period of my public prelections, to be presented to the society, as a substitute for the essay of an absent friend, and was sent off to London the morning after it was read. The positive pole or wire connected with the zinc end of the battery was that which I applied to the nerve ; and the negative, or that connected with the copper end, was that which I applied to the muscles. This is a matter of primary importance, as the following experi- ments will prove. Prepare the posterior limbs of a frog for voltaic electrization, leaving the crural nerves connected, as usual, to a detached portion of the spine. When the excitability has become nearly exhausted, plunge the limbs into the water of one wine glass, and the crural nerves with their pendent portion of spine into that of the other. The edges of the two glasses should be almost in contact. Then taking a rod of zinc in one hand, and a rod of silver (or a silver tea-spoon) in the other, plunge the former into the water of the limbs' glass, and the latter into that of the nerves' glass, without touching the frog itself, and gently strike the dry parts of the bright metals together. Feeble convulsive movements, or mere twitching of the fibres, will be perceived at every contact. Reverse now the position of the metallic rods, that is, plunge the zinc into the nerves' glass, and the silver into the other. On renewing the contact of the dry surfaces of the metal now, very lively convulsions will take place ; and if the limbs are skilfully dis- posed in a narrowish conical glass, they will probably spring out to some distance. This interesting experiment may be agreeably varied iu the following way, with an assistant opera- tor : Let that person seize, in the moist fingers of his left hand, the spine and nervous cords of the prepared frog ; and in those of the right hand, a silver rod ; and let the other person lay hold of one of the limbs with his right hand, while he holds a zinc rod in the moist fingers of the left. On making the metallic contact, feeble convulsive twitchings will be perceived, as before. Holding still the frog as above, let them merely exchange the pieces of metal. On renewing the contacts now, lively movements will take place, which become very conspicuous, if one limb be held nearly hori- zontal, while the other hangs freely down. At each touch of the voltaic pair, -the drooping GAN 482 GAR limb will start up, and strike the hand of the experimenter. It is evident, therefore, that for the pur- poses of resuscitating dormant irritability of nerves, or contractility of their subordinate muscles, the positive pole must be applied to the former, and the negative to the latter. I need scarcely suggest, that to make the above experiments analogous to the condition of a warm-blooded animal, apparently dead, the frog must have its excessive voltaic sensibility considerably blunted, and brought near the standard of the latter, before beginning the ex- periments. Otherwise that animal electro- scope, incomparably more delicate than the gold leaf condenser, will give very decided con- vulsions with either pole. At the conclusion of the article Caloric, I have taken the liberty of suggesting some simple and ready methods of supplying warmth to the body of a drowned person. GAMBOGE is a concrete vegetable juice, the produce of two trees, both called by the Indians caracapulli (gambogia gutta, Lin.), and is partly of a gummy and partly of a re- sinous nature. It is brought to us either in the form of orbicular masses, or of cylindrical rolls of various sizes ; and is of a dense, com- pact, and firm texture, and of a beautiful yel- low. It is chiefly brought to us from Cam- baja, in the East Indies, called also Cambodja, and Cambogia ; and hence it has obtained its name of cambadium, cambogium, gambogium. It is a very rough and strong purge ; it operates both by vomit and stool, and both ways with much violence, almost in the instant in which it is swallowed, but yet, as it is said, without griping. The dose is from two to four grains as a cathartic ; from four to eight grains prove emetic and purgative. The roughness of its operation is diminished by giving it in a liquid form sufficiently diluted. This gum resin is soluble both in water and in alcohol. Alkaline solutions possess a deep red colour, and pass the filter. Dr. Lewis in- forms us, that it gives a beautiful and durable citron-yellow stain to marble, whether rubbed in substance on the hot stone, or applied, as dragon's blood sometimes is, in form of a spirituous tincture. When it is applied on cold marble, the stone is afterwards to be heated to make the colour penetrate. It is chiefly used as a pigment in water co- lours, but docs n6t stand. According to M. Braconnot, it consists in 100 parts of 20 gum and 80 resin. Ann. de Chim. t. 68. p. 36. GANGUE. The stones which fill the cavities that form the veins of metals are called the gangue, or matrix of the ore. GARNET. Professor Jameson divides this mineral genus into 3 species, the pyra- midal garnet, dodecahedral garnet, and pris- matic garnet. I. Pyramidal contains 3 sub-species, Ve- suvian, Egeran, and Gehlenite, which see. II. Dodecahedral garnet contains 9 sub- species. 1. Pyreneite. 2. Grossulare. 3. Melanite. 4. Pyrope. 5. Garnet. 6. Al- lochroite. 7- Colophonite. 8. Cinnamon- stone. 9. Helvin. III. Prismatic garnet ; the grenatite. We shall treat here only of the garnet, proper. Of this sub-species we have two kinds, the precious and common. Precious or noble garnet. Colours dark red, falling into blue. Seldom massive, some- times disseminated, most commonly in round- ish grains, and crystallized. 1. In the rhom- boidal dodecahedron, which is the primitive form ; 2. Ditto truncated on all the edges ; 3. Acute double eight-sided pyramid ; and 4. Rectangular four-sided prism. The surface of the grains is generally rough, uneven, or granulated ; that of the crystals is always smooth. Lustre externally glistening ; in- ternally shining, bordering on splendent. Frac- ture couchoidal. Sometimes it occurs in la- mellar distinct concretions. Transparent or translucent. Refracts single. Scratches quartz, but not topaz. Brittle. Rather difficultly frangible. Sp. g. 4-0 to 4,2 Its constituents are, silica, 39.66, alumina 19-66, black oxide of iron 39-68, oxide of manganese 1 . 80. Ber- zelius. Before the blowpipe it fuses into a black enamel, or scoria. It occurs imbedded in primitive rocks and primitive metalliferous beds. It is found in various northern coun- ties in Scotland ; in Norway, Lapland, Swe- den, Saxony, France, &c. It is cut for ring- stones. Coarse garnets are used as emery for polishing metals. The following vitreous com- position imitates the garnet very closely : Purest white glass, 2 ounces Glass of antimony, 1 ounce Powder of Cassius, 1 grain Manganese, 1 grain. Jameson. The garnets of Pegu are most highly valued, Common garnet. Brown and green are its most common colours. Massive, but never in grains or angular pieces. Sometimes crystal- lized, and possesses all the forms of the precious garnet. Lustre shining or glistening. Fracture fine-grained, uneven. More or less translucent ; the black kind nearly opaque. It is a little softer than precious garnet. Rather difficultly frangible. Sp. gr. 3.7- Before the blowpipe it melts more easily than precious garnet. Its constituents are 38 silica, 20-6 alumina, 31-6 lime, 10-5 iron. Vauquelin. It occurs mas- sive or crystallized in drusy cavities, in beds, in mica-slate, in clay-slate, chlorite-slate and primitive trap. It is found at Kilranelagh and Donegal in Ireland ; at Arendal and Drammen in Norway, and in many other countries. On account of its easy fusibility and richness in iron, it is frequently employed as a flux in smelting rich iron ores. It is GAS 483 GAS sometimes used instead of emery by lapidaries. Jameson. GARNET (RESINOUS). The mineral called Colophonite. GARNET - BLENDE, oa ZINC - BLENDE. A sulphuret of zinc. GAS. This name is given to all perma- nently elastic fluids, simple or compound, except the atmosphere, to which the term Air is appropriated. The solid state is that in which, by the pre- dominance of the attractive forces, the particles are condensed into a coherent aggregate ; the gaseous state is that in which the repulsive forces have acquired the ascendency over the attractive ; and the liquid condition represents the equilibrium of these two powers. Vapours are elastic fluids, which have no permanence ; since a moderate reduction of temperature causes them to assume the liquid or solid aggregation. Cohesive attraction among homogeneous particles is the great antagonist to chemical affinity, the attraction of composition, the force which tends to bring into intimate union hete- rogeneous particles. Hence the juxtaposition of two solids, of a solid and a liquid, or even of two liquids, may never determine their chemical combination, however strong their reciprocal affinity shall be. In the case of two liquids, or a liquid and k a solid, mere juxtaposition requires that the denser body be undermost, and that no dis- engagement of gas, or external vibration, agitate the surfaces in contact. Hence those world framers, who ascribe the saltness of the sea to supposed beds of rock salt at its bottom, have still the phenomenon of the strong im- pregnation of the surface to explain ; for the profound tranquillity which is known to reign at very moderate depths in this mighty mass, would for ever prevent the diffusion of the saturated brine below, among the light waters above. Or if this tranquillity be disputed, then progressive density from above down- wards should be found, and continually in. creasing impregnation. Now none of these results has occurred. But with gases in con- tact, there is no obstacle, from cohesive at- traction, to the exertion of their reciprocal affinities. Hence, however feeble these may be, they never fail, sooner or later, to cause an intimate mixture of different gases, in which the ultimate particles approach within the limit corresponding to their reciprocal action. The difference of density may delay, but cannot prevent, uniform diffusion Thus we see that known powers can account for the phenomena. There is no need therefore of having recourse to the curious hypothesis of Mr. Dalton, that one gas is a neutral unre- sisting void with regard to another, into which it will rush by its innate expansive force. But of this notion sufficient notice has been taken in the article AIR (ATMOSPHERIC). The principle of gaseous combination, first broached in the neglected treatise of Mr. Higgins, but since developed with consum- mate sagacity from the original researches of M. Gay Lussac, has thrown a new light on pneumatic chemistry, which has been reflected into all its mysterious departments of animal and vegetable analysis- Having given the details under the article Equivalents (Che- mical), we shall merely state in this place, that the combinations of gaseous bodies are always effected in simple ratios of the volumes, so that if we represent one of the terms by unity, or 1, the other is 1, 2, or at most 3. Thus ammoniacal gas neutralizes exactly a volume equal to its own, of the gaseous acids. It is hence probable, that if the alkalis and acids were in the elastic state, they would all combine, each in equal volume with another, to produce neutral salts. The capacity of saturation of the acids aijd alkalis, measured by volumes, would then be the same; and perhaps this would be the best manner of esti- mation. In the following tables of gaseous combination, bodies naturally in the solid state, like sulphur, carbon, and iodine, will be re- ferred to their gaseous densities, or the bulks which they occupy relative to their weights, when diffused by a chemical combination among the particles of a permanently elastic fluid. This view of the subject, first introduced by M. Gay Lussac, and happily exemplified in his excellent memoir on iodine, will sim- plify our representation of many compounds. Finally, the apparent contractions or conden- sations of volume, which gases suffer by their reciprocal affinity, have also simple ratios with the volume of one of them ; a property pe- culiar to gaseous bodies. "We shall distribute under the following heads our general obser- vations on gases. 1. Tabular views of the densities and combining ratios of the gases. 2. A description of their general habitudes with solids and liquids. 3. An account of the principal modes of analyzing gaseous mixtures. 4. Of gasometry, or the measure- ment of the density and volume of gases. I. We are indebted to Dr. Prout for an able memoir on the relation between the spe- cific gravities of bodies in their gaseous state, and the weights of their atoms, or prime equi- valents, inserted in the sixth volume of the Annals of Philosophy. His observations are founded on M. Gay Lussac's doctrine of vo- lumes. Dr. Prout considers atmospheric air as a chemical compound, constituted by bulk of four volumes of azote and one of oxygen ; and reckoning the atom of oxygen as 10, and that of azote as 17-5, it will be found to con- sist of one atom of oxygen, and two atoms of azote, or per cent, of oxygen 22-22 Azote 77-77 Though almost all experiments have hitherto led us to regard the atmosphere as containing 21 volumes in the 100 of oxygen, we must, i i 2 GAS 484 GAS in this view, ascribe the excess of one per cent, to an error of observation. Now, it is not impossible, that in the explosive eudiometer with hydrogen over mercury, or in the nitrous gas eudiometer over water, one per cent, of azote may be pretty uniformly condensed. Calling the prime equivalent of oxygen 1-000, and that of azote 1-75, as deduced both from nitric acid and ammonia, we may easily calculate the specific gravities of these two gaseous elements of the atmospheric com- pound, itself being represented in sp. gr. by 1-00, and in the relative -weigfits of its con- stituents, by 1-00 -fl-75 X 2; or 22-22 + 77-77. The ancient problem of Archimedes, for determining the fraud of the goldsmith in making king Hiero's crown, which is so im- portant in chemistry for computing the mean density of a compound, the specific gravities of whose two constituents are given ; and for thence enabling us, by comparing that result with the density found by experiment, to discover the change of volume due to the che- mical action, is of peculiar value in pneumatic investigations. It will enable us to solve, without difficulty, the two following problems : - 1st, Having given the specific gravity of a mixed gas, and the specific gravities of its two constituent gases, to determine the volume, and consequently the quantity, of each pre- sent in the mixture. 2d, Having given the specific gravity of a mixed gas, and the proportions by weight and volume of its constituents, to determine the specific gravities of each of its constituents. In both cases, no chemical condensation or expansion is supposed, and only two gases are concerned. 1st, Let d be the sp. gr. of the denser gas ; / of the lighter gas ; m mixed gas ; x the volume of the denser gas ; y of the lighter gas ; v total volume of the compound. Then x = ,, P(l Vr, .o *y = Then *** + ny s , the sp. gr. of the com- m-\-n pound whose weight = 1. But the volume of one body multiplied into its specific gravity, is to the volume of an- other, multiplied into its specific gravity, as the weight of the first is to that of the se- cond, or mx : ny : : a : ft And m + n ny = ~- t if s = 1. ( m _i_ n \i Whence y -> \ / -, an + bn - - (d m)-\-(m ly v (d m)j Dr. Prouthas very ingeniously applied this formula to the determination of the specific gravities of oxygen and azote, which are, Oxygen, 1.1111 Azote, 0.9722 His investigation of the specific gravities of hydrogen from that of ammonia is conducted on principles still less disputable. The mean of the experimental results obtained by MM. Biot and Arago and Sir H. Davy on am- moniacal gas is 0-5902. Now it has been demonstrated, that two volumes of it are re- solvable into 4 volumes of constituent gases, of which 3 volumes are hydrogen and 1 azote. Hence, if from double the specific gravity of ammonia, we subtract the specific gravity of azote, the remainder divided by 3 will be the specific gravity of hydrogen. Or, putting the same thing into an algebraic form, on the principle that the sum of the weights, divided by the sum of the volumes, gives the specific gravity of the mixture, let a- be the specific gravity of hydrogen, then ex- periment shows, that 3 * + ' 9722 = from one or other of which formulae, the vo- lume of one or other constituent may be found ; and by multiplying the volume by the specific gravity, its weight is given. The same formula is stated in words under the article Coal Gas. 2d, When the specific gravities of the com- ponents are sought ; the specific gravity of the compound, as well as the volume and weight of each component being given, we have the following formula : Let x be the sp. gr. of that whose weight is a and volume m. y be the sp. gr. of that whose weight is b and volume n. 2 x 0-5902-0-9722 Whence a? = : = 0-0694. o The density of hydrogen therefore is to that of azote, atmospherical a air, and oxygen, as 1 to 14, 1 to 144, and 1 to 16, respec- tively. And with regard to muriatic acid gas, it is well known to result from the union of chlorine and hydrogen in equal volumes, without any condensation ; therefore if we call the sp. gr. of the compound gas 1.285, and from the double of that number deduct the sp. gr. of hydrogen, we shall have the sp. gr. of chlorine + = 1-285 X 2 0-0694 = 2-5006, which may be converted into the even number 2-5 without any chance of error. See Sect. IV. In the common tables of equivalent ratios, adapted to the hypothesis that water is a com- pound of one atom of oxygen and one of hy- drogen, or of half a volume of the former and one volume of the latter, we must compute the ratios pf gaseous combination, among different GAS 485 GAS bodies, by multiplying the weight of their atom of hydrogen were reckoned unity, then the or their primeequivalentsbyhalfthesp.gr. of doctrine of volumes and prime equivalents oxygen = 0- 5555. If the volume and sp. gr. would coincide. General Table of Gaseous Bodies, by DR. URE. Barometer 30 Thermometer 60 F. NAMES. Sp. gr. air == 1.00. Weight of 100 cubic inches. Weight of prime equiv. oxygen c= 1. Constituents by volume. 1 Resulting 1 volume. Constituent prime equivalents. Hydrogen, 0-0694 2-118 0-125 Carbon, 0-4166 12-708 0-750 Steam of water, 0-481 14-680 1-125 2 hyd. 4- 1 oxyg. 1 hyd. 4- 1 oxyg. Subcarb. hydrogen, 0-5555 17-000 1-000 2 hyd. 4- 1 carb. 1 2 hyd. 4- 1 carb. Ammonia, 0-5902 18-000 2-125 3 hyd. -j- I azote 2 3 hyd. 4- 1 azote Carbon ous oxide, Carburetted hydrogen, 0-9722 0-9722 29-65 29-65 1-750 0-875 2 carb. + 1 oxyg. 1 carb. 4- 1 hyd. 2 1 carb. 4- 1 oxyg. |jl carb. 4- 1 hyd. Azote, 0-9722 29-65 1-750 Prussic acid, 0-9374 28-59 3-375 cyan. 4~ 1 hyd. 2 1 cyan. 4~ 1 hyd. Atmospheric air, 0000 30-519 4-500 oxy. 4~ 4 azote 5 1 oxyg. -f- 2 azote Deutoxide of azote, .0416 31-77 3-750 oxy. -j- 1 azote 2 2 oxyg. -j- 1 azote Oxygen, 1111 33-888 1-000 Sulphur, 1111 33-888 2-000 Sulphuretted hydrogen, 1805 36-006 2.125 hyd. 4-1 sulph. 1 hyd. 4~ 1 sulph. Protophosphd. hydrogen, -215 37-027 4-375 phos. -f- 3 hyd. 2 phos. 4- 3 hyd. Muriatic acid, -2840 39-183 4-625 hyd. 4- 1 chlo. 2 hyd. 4- 1 chlor. Carbonic acid, 5277 46-596 2-750 carb. -j- 1 oxyg. 1 carb. + 2 oxyg. Protoxide of azote, 5277 46-596 2-750 oxy. 4" 2 azote 2 oxyg. 4- 1 azote Alcohol vapour, 1-6133 49-20 2-875 1 ol. gas 4- 1 wa. 1 2 ol. gas. -f-1 water Perphosphd. hydrogen, 1-771 53-710 4-250 1 phos. 4-3 hyd. 2 1 phos. 4- 2 hyd. Cyanogen, ^ 1-8055 55-07 3-25 2 carb. 4~ 1 azote 1 2 carb. -f- 1 azote Dhloroprussic acid, 2-1527 65-69 7-75 1 cya. 4- I chlo. 2 1 cyan, -j- 1 chlor. Muriatic ether, 2-2562 67-68 5-5 1 mur.-j-l ol. gas 2 jl m. ac.4~l ol. gas Sulphurous acid, 2-222 67-77 4-000 1 oxy.4~l sulph. 1 2 oxyg. -}-l sulph. Phosphorus, 2-222 67-77 4-000 Deutoxide of chlorine, 2-361 72-0 9-50 2 oxy. 4~ 1 chlo. 2 1 chlor. 4-4 oxyg. Fluoboric acid, 2-371 72-312 8-500 Protoxide of chlorine, 2-44 74.42 5-50 2 oxy. 4- 4 chlo. 5 1 oxyg. 4-1 chlor. Chlorine, 2-500 76-25 4-50 Sulphuric ether vapour, 2.586 78-87 2-875 2 olef. 4- 1 wat. 4 olef. 4- 1 water Nitrous acid, Sulphuret of carbon, 2-638 2-638 80-48 80-66 4-75 4-750 3 oxy. 4~ 2 azote 2 carb. 4-4 sulph. 2 2 3 oxyg. 4~ 1 azote 2 sulph. -j- 1 carb. Sulphuric acid, Chlorocarbonous acid, 2-777 3-472 84-72 105-9 5-000 6-25 3 oxy. + 2 sulph. 1 chl.4-l car. ox. n 1 3 oxyg. 4-1 sulph. 1 chlo. 4-1 car. ox. Sal ammoniac, 3-746 114-3 6-75 2 amm. 4-2 mur. 1 1 am. 4-1 mu. acic Nitric acid, 3-75 114-37 6-75 5 oxyg. 4- 2 azote 2 5 oxyg. 4- 1 azote Hydriodic acid, 4-340 132-37 15-625 1 hyd. 4- 1 iodine 2 1 hyd. 4- 1 iodine Oil of turpentine, 5-013 152-9 Chloric acid, 5-277 160-97 9-5 5 oxyg. 4- 2 chlo. 2 5 oxyg. 4~1 chlor. Fluoborate of ammonia, 5-922 180- 10-625 2 am. 4-2 fluob.! I 1 am. 4~ 1 fiuobor. Subfluob. ammonia, 7-10 216-7 12-750 4 am. -f- 2 fluob.! 1 ,2 am. 4- 1 fluobor. Tritosubfluob. ammonia, 8-28 252- 14-875 6 am. -f- 2 fluob. 1 3 am. + 1 fluobor. Fluosilicate of ammonia, 2 am. 4- 1 acid.) In the preceding table I have endeavoured to assemble the principal features of gaseous combination. For the properties of these different gases, see the separate articles in the Dictionary. II. Of the general habitudes of gaseous matter with solids and liquids. Mr. Dalton has written largely on these relations ; but his results are so modified by speculation, that it is difficult to distinguish fact from hypothesis. Dr. Henry, however, made some good re- searches on the subject of this division, but GAS 486 GAS they have since been t>o much extended and improved by M. de Saussure, that I shall take his elaborate researches for my guide. His M emoir on the absorption of the gases by different bodies, was originally read to the Geneva Society on the 16th April, 1812, and appeared in Gilbert's Annalen der Physik for July 1814, from which it was translated into the 6th volume of the Annals of Philosophy. 1. Of the absorption of unmixed gases by solid bodies. Of all solid bodies charcoal is the most re- markable in its action on the gases. In M. de Saussure's experiments, the red-hot charcoal was plunged under mercury, and introduced, after it became cool, into the gas to be ab- sorbed, without ever coming into contact with atmospherical air. TABLE of the Volumes of Gases absorbed by one Volume of GASES. Charcoal. Meer- schaum. Adhesive slate. Ligniform asbestus. Saxon hydroph. Quartz. Ammonia, ^ ^ 90 15 11-3 12-75 64 10 Muriatic acid, " | 85 17 __ Sulphurous acid, / 65 7-37 Sulphuretted hydrogen, 55 11-7 Nitrous oxide, 40 3-75 Carbonic acid, ,* 35 5-26 2 1-7 1-0 0-6 Olefiant gas, '',' 35 3-70 1-5 1-7 0-8 0-6 Carbonic oxide, 9-42 M7 055 0-58 Oxygen, ' . 9-25 1-49 0-7 0-47 06 0-45 Azote, 7-5 1-6 0-7 0-47 06 0-45 Oxycarburetted hydrogen ) from moist charcoal, J 50 0-85 0-55 0-41 Hydrogen, 1-75 0-44 0-48 0-31 0-4 0-37 The absorption was not increased by al- lowing the charcoal to remain in contact with the gases after 24 hours ; with the exception of oxygen, which goes on condensing for years, in consequence of the slow formation and absorption of carbonic acid. If the char- coal be moistened, the absorption of all those gases that have not a very strong affinity for water, is distinctly diminished. Thus box- wood charcoal, cooled under mercury, and drenched in water while under the mercury, is capable of absorbing only 15 volumes of carbonic acid gas; although, before being moistened, it could absorb 35 volumes of the same gas. Dry charcoal, saturated with any gas, gives out, on immersion in water, a quan- tity corresponding to the diminution of its ab- sorbing power. ^During the absorption of gas by charcoal, an el; vation of temperature takes place, proportional to the rapidity and amount of the absorption. The vacuum of the air- pump seems to possess the same influence as heat, in rendering charcoal capable of absorb- ing gaseous matter. A transferrer with a small jar containing a piece of charcoal was exhausted, and being then plunged into a pneumatic trough, was filled with mercury. The charcoal was next introduced into a gas, and absorbed as much of it as after having been ignited. As the rapid absorption of car- bonic acid gas by charcoal can raise the ther- mometer 25, so its extraction by the air-pump sinks it 7-5. Though charcoal possesses the highest ab- sorbent power, yet it is common to all bodies which possess a certain degree of porosity, after they have been exposed to the action of an air-pump. Meerschaum, like charcoal, absorbs a greater bulk of rare than dense gas. Dried woods, linen threads, and silks, also absorb the gases. Of ammonia, hazel ab- sorbs 100 volumes, mulberry 88, linen thread 68, silk 78; of carbonic acid, in the above order, M, 0-46,0-62, 1-1 ; of this gas, fir ab- sorbed 1-1, and wool 1-7- The rate of absorption of different gases appears to be the same, in all bodies of similar chemical properties. All the varieties of as- bestus condense more carbonic acid gas than oxygen gas ; but woods condense more hy- drogen than azote. Yet the condensations themselves in different kinds of asbestus, or wood, or charcoal, are very far from being equal. Ligniform asbestus absorbs a greater volume of carbonic acid gas than rock cork ; so does hydrophane than the swimming quartz of St Ouen, and the quartz of Vauvert ; and the absorption of gases by boxwood charcoal is much greater than by fir charceal. These differences are not in the least altered, if, instead of equal volumes, equal weights of charcoal be employed. It is curious that a piece of solid charcoal absorbs 7^ volumes, and the same reduced into fine powder absorbs only 3 volumes. The absorbing power of most kinds of charcoal increases as the specific GAS 487 GAS gravity increases ; and it is obvious, that the pores must become smaller and narrower with the increase of density. Charcoal from cork, of a specific gravity not exceeding 0"-1, ab- sorbed ho sensible quantity of atmospheric air. Charcoal from fir, sp. gr. 0-4, absorbed 4| times its volume of atmospherical air ; that from boxwood, sp. gr. 0-6, absorbed 7^ of air; and pit-coal of vegetable origin from Russiberg, sp. gr. 1-326, absorbed 10^ times its volume of air. But, as the density aug- ments, we arrive at a limit, when the pores become too small to allow gases to enter. Thus, the black-lead of Cumberland, con- taining 0-96 of carbon, sp. gr. 2-17, produces no alteration on atmospherical air. But this correspondence between the power of absorbing and the specific gravity, is only accidental. Accurate experiments show remarkable de- viations from this rule. The different kinds of charcoal, whether of similar or dissimilar *p. gravities, always differ from each other in their organization. They cannot be considered as resembling a sponge, whose pores and den- sity may be modified by pressure. On the whole it appears, that the property of condensing gases, possessed by some solids, js, within certain limits, in the inverse ratio of the internal diameter of the pores of the absorbing bodies. But besides the porosity, there are other two circumstances which must be attended to in these absorptions ; 1. The different affinities which exist between the gases and the solid bodies; and, 2. The power of expansion of the gases, or the op- position they make to their condensation, at different degrees of heat and atmospherical pressure. The experiments hitherto described relate to the absorption of a single gas, not mixed with any other. But, when a piece of char- coal saturated with either oxygen, hydrogen, azote, or carbonic acid, is put into another gas, it allows a portion of the first to escape, in order to absorb into its pores a portion of the second gas. The volume of gas thus expelled from charcoal by another gas, varies according to the proportion in which both gases exist in the unabsorbed residue. The quantity expelled is greater, the greater the excess of the expelling gas. Yet it is not possible, in close vessels, to expel the whole of one gas out of charcoal, by means of an- other ; a small quantity always remains in the charcoal. Two gases, united by absorption in char- coal, often experience a greater condensation than each would in a separate state. For example, the presence of oxygen gas in char- coal facilitates the condensation of hydrogen gas ; the presence of carbonic acid gas, or of azote, facilitates the condensation of oxygen gas ; and that of hydrogen the condensation of azote. Yet this effect does not take place in all cases, with the four gases now men- tioned ; for the presence of azote in charcoal does not promote the absorption of carbonic acid gas. When the absorption of one of the four named gases has been facilitated by an- other of them, no perceptible combination be- tween the two takes place, at least within the interval of some days. So, for example, not- withstanding the assertion of Rouppe and Van Noorden, no separation of water appears, when charcoal saturated with hydrogen at the com- mon temperatures is put into oxygen gas ; or when the experiment it reversed. Nor has azote and hydrogen been united in this way into ammonia, or azote and oxygen into nitric acid. 2. Absorption of gases by liquids. " That all gases are absorbed by liquids," says M. de Saussure, " and that most of them are again separated by heat, or the diminution of external pressure, has been long known. We now possess accurate results respecting the rate of this absorption. For a set of careful and regular experiments on this subject, we are indebted to Dr. Henry of Manchester. Mr. Dalton has a little altered some of these results ; and, by means of them, has contrived a theory which not only explains the absorp- tion of gases by water, but by all other liquids ; but it is in opposition to most of the results which I have obtained by means of solid porous bodies." The following table exhibits the volumes of the different gases absorbed according to the accurate experiments of Saussure, by 100 volumes of GASES. Water. Alcohol sp.gr. 0.84. Naphtha sp. gr. 0.7S4. Oil of lav. sp- gr. 0.88 Olive oil. Satur. solution mur. pot. Sulphurous acid 4378 11577 Sulphuretted hydrogen, . 253 606 Carbonic acid, 106 186 169 191 151 61 Nitrous oxide, 7 153 254 275 150 21 Olefiant gas, ^ . Jfc 15-3 127 261 209 122 10 Oxygen gas, 6-5 16-25 __ Carbonous oxide, . 6-2 14-50 20 15-6 14-2 52 Oxycarburetted hydrogen 5-1 7-0 Hydrogen, 4-6 5-1 Azote .... 41 42 GAS 488 GAS The above liquids were previously freed from air, as completely as possible, by long and violent boiling. But those which would have been altered or dissipated by the appli- cation of such a heat, as oils, and some saline solutions, were freed from air by means of the air-pump. To produce a speedy and complete absorption, a large quantity of those gases which are absorbed only in small quantity by liquids, as azote, oxygen, and hydrogen, was put, with a small quantity of the liquid, into a flask, which was furnished with an excellent ground stopper. The flask was agitated for a quarter of an hour. This method is difficult, and requires much attention. With respect to all the gases of which the liquid absorbs more than l-7th of its bulk, M. de Saussure proceeded in the following manner: He placed them over mercury, in a tube fully l~ inches internal diameter, and let up a column of the absorbing liquid, from about If to 2i inches long. The absorption was promoted by agitation, and its quantity was not deter- mined till the gas and the liquid had been in contact for several days. A hundred volumes of water absorb about five volumes of atmospherical air, when the mass of air is very great, in comparison of that of the water. " From these experiments," says M. de Saussure, * it appears, contrary to Dalton's assertion, that the absorption of gases, by dif- ferent liquids, not glutinous, as water and alcohol, is very far from being similar. The alcohol, as we see, often absorbs twice as much of them as the water does. In gases which are absorbed in small quantities, this difference is not so striking, because, with respect to them, the absorptions of the alcohol can be less accurately determined, on account of the air which still remains in it, after being boiled. " These experiments agree no better with the law which Dalton thinks he has ascer- tained in the absorption of different gases by one and the same liquid ; for I find too great a difference between the quantity of carbonic acid, sulphuretted hydrogen, and nitrous oxide gases, absorbed by the same liquids (which Dalton considers as completely equal), to be able to ascribe it to errors in the experi- ments." 3. Of the influence of chemical affinity on the absorption of the gases. If such an influence did not exist, the gases would be absorbed by all liquids in the same order. Table of the volumes of gases ab- sorbed by 100 volumes of Names of Naph. Oil of lav. Olive Solution gases, sp.gr.0.784. sp.gr. 0.88. oil. mur. pot. Olefiantgas, 261 209 122 10 Nitrous oxide, 254 275 150 21 Carbonic acid, 169 191 151 61 Carbo. oxide, 20 15-6 14-2 5-2 ' It follows," says M. de Saussure, " from these experiments, that in liquids, as well as in solid bodies, great differences take place in the order in which gases are absorbed by them, and that, in consequence, these absorp- tions are always owing to the influence of che- mical affinity. Solid bodies appear, under the same circumstances, to produce a greater condensation of all gases, in contact with which they are placed, than liquid bodies do. I have met with no liquid which absorbs so great a volume of carbonic acid, olefiant gas, azotic gas, carbonous oxide, and nitrous oxide, as charcoal and meerschaum do. The dif- ference is probably owing to this circumstance, that liquids, in consequence of the great mo- bility of their parts, cannot compress the gases so strongly as is necessary for greater conden- sation, certain cases excepted, when very pow- erful chemical affinities come to their assist- ance ; as, for example, the affinity of ammo- nia and muriatic acid for water. Only in these rare cases do liquids condense a greater quan- tity of gases than solid bodies. According to Thomson, water in the mean temperature of the atmosphere absorbs 516 times its bulk of muriatic acid gas, and 780 times its bulk of ammoniacal gas." In the articles muriatic acid and ammonia in the first edition of this Dictionary, I have shown these determinations of Dr. Thomson to be erroneous. 4. Influence of the viscidity, and the specific gravity of liquids on their absorption of gases. Carbonic acid gas was placed in contact with one volume of the different liquids. The tem- perature in all the experimenta*/as 62-5. GAS 489 GAS LIQUIDS. Sp.gr. Volume of car. acid gas absorbed. 100 parts of the solution, contain Alcohol, 0-803 2-6 Sulph. ether, 0-727 2-17 Oil of lavender, 0-880 1-91 Oil of thyme, 0-890 1-88 Spirit of wine, 0-840 1-87 Rectified naphtha, Oil of turpentine, 0-784 0-860 1.69 1-G6 Linseed oil, 0-940 1-56 Olive oil, 0-915 1-51 Water, 1-000 1.06 Sal ammoniac, 078 0-75 27-53 crystals, sat sol. Gum arable, 092 0-75 25. gum, Sugar, .104 0-72 25. sugar, Alum, .047 0-70 9-14 cry. al. sat. sol. Sulphate of potash, .077 0-62 9-42 c. s. sat. soL Muriate of potash, .168 0-61 26-0 c. s. sat. sol. Sulphate of soda, .105 0-58 11-14 dry salt, sat. sol. Nitre, 1.139 0-57 20-6 sat. sol. Nitrate of soda, 1.206 0-45 26.4 sat. sol. Sulphuric acid, 1.840 0-45 Tartaric acid, 1.285 041 53-37 c. acid, sat. sol. Common salt, 1.212 0-329 29. s. sat sol. Muriate of lime, 1.402 0-261 40-2 ignited salt, sat. sol. Though the influence of the viscidity of a liquid be small with regard to the amount of the absorption, yet it increases the time ne- cessary for the condensation of the gas. In general, the lightest liquids possess the great- est power of absorbing gases ; with the excep- tion of those cases where peculiar affinities in- terfere. 5. Influence of the barometrical pressure on the absorption of gases by liquids. M. de Saussure shows, that in liquids the quantities of gases absorbed are as the com- pressions ; while in solid bodies, on the con- trary, as the gases become less dense, the ab- sorption seems to increase. Dr. Henry had previously demonstrated, that the quantity of carbonic acid taken up by water, is propor- tional to the compressing force ; a fact long ago well known and applied by Schweppe, Paul, and other manufacturers of aerated al- kaline waters. 6. Simultaneous absorption of several gases by water. M. de Saussure thinks it probable, that the absorption of the different gases at the same time by liquids, is analogous to what he ob- served with respect to solid bodies. Henry, Dalton, Van Humboldt, and Gay Lussac, had already remarked, that water saturated with one gas, allows a portion of that gas to escape, as soon as it comes in contact with another gas. " It is indeed evident, accord- ing to Dalton \s theory," says M. de Saussure, " that two gases absorbed into a liquid, should really occupy always the same room as they would occupy, if each of them had been ab- sorbed singly, at the degree of density which it has in the mixture.'* To obtain results on this subject, approaching to accuracy, he was obliged to make mixtures of carbonic acid with oxygen, hydrogen, and azotic gases ; for the last three gases are absorbed by water in so small a proportion, that the different con- densations which take place cannot be con- founded with errors in die experiments. 1. Water, and a mixture of equal measures of carbonic acid and hydrogen gas. He brought 100 measures of water, at the temperature of 62, in contact with 434 mea- sures of equal volumes of carbonic acid and hydrogen. The absorption amounted to 47-5 volumes, of which 44 were carbonic acid, and 3-5 hydrogen. If we compare the space which the absorbed gases occupy in the water, with that which they would occupy, accord- ing to the preceding table of absorption of un- mixed gases, we find that the presence of one of the gases has favoured the absorption of the other, as far as the relative space goes, which each would occupy separately in the water. 2. Water, and a mixture of equal parts of carbonic acid and oxygen gas. 100 volumes of water at 62 absorbed from 390 volumes of this mixture 52- 1 vo- lumes, of which 47-1 volumes were carbonic acid, and 5 volumes oxygen gas. Here also the condensation is 'greater than when the gases are separate. GAS 490 GAS 3. Water and a mixture of carbonic acid gas and azote. 100 volumes of water absorbed from 357-6 volumes of this mixture, at the above tempe- rature, 47-2 volumes, of which 43-9 volumes were carbonic acid, and 3-3 azote. The results of these experiments, as we perceive, agree completely with each other ; but none of them corresponds with Dalton's theory, according to which, the volume of carbonic acid absorbed should be just one-half of that of the absorbing liquid; and likewise the volumes of the other gases absorbed should be much smaller than M. de Saussure found them actually to be. A mixture of oxygen and hydrogen gases, in the proportions for forming water, by agitation with that liquid, was absorbed in the proportion of 5^ volumes to 100 volumes of the liquid. In an appendix, M. de Saussure describes minutely the judicious precautions he took to ensure precision of re- sult ; which leave little doubt of the accuracy of his experiments, and the justness of his conclusions. They are as fatal to Mr. Dal- ton's mechanical fictions concerning the rela- tion of liquids and gases, as MM. Dulong and Petit's recent researches have been to his geometrical ideas on the phenomena of heat. III. Of Gaseous Analysis. This department of chemistry, whose great importance was first shown by Cavendish, Priestley, and Barthollet, has lately acquired new value in consequence of M. Gay Lussac's doctrine of volumes, his determination of the specific gravities of vapours, and sagacious application of both principles to the develop- ment of many combinations hitherto intricate and inexplicable. Let us first take a general view of the cha- racters of the different gases. Some of them are coloured, others diffuse white vapours in the air ; some relume a taper, provided a point of its wick remains ignited ; others are acid, and redden tincture of litmus ; one set have no smell, or but a faint one ; a second set are very soluble in water ; a third are soluble in alkaline solutions ; and a fourth are them- selves alkaline. Some gases possess several of these characters at once. 1 . The coloured gases are nitrous acid, chlo- rine, the protoxide and deutoxide of chlorine. The first is red, the rest yellowish- green, or yellowish. 2. Gases producing white vapours in the air. Muriatic acid, ftuoboric, fluosilicic, and hydriodic. 3. Gases inflammable in air by contact of the lighted taper. Hydrogen, subcarburetted and carburetted hydrogen, subphosphuretted and phosphuretted hydrogen, sulphuretted hydrogen, arsenuretted hydrogen, telluretted hydrogen, potassuretted hydrogen, carbonous oxide, prussine or cyanogen. 4. Gases which rekindle the expiring taper. Oxygen, protoxide of azote, nittous acid, and the oxides of chlorine. 5. Add gases, which redden litmus. Nitrous, sulphurous, muriatic, fluoboric, hydriodic, fluosilicic, chlorocarbonous, and carbonic acid; the oxides of chlorine, sulphuretted hydrogen, telluretted hydrogen, and prussine. 6. Gases destitute of smell, or possessing but a feeble one. Oxygen, azote, hydrogen, sub- carburetted and carburetted hydrogen, carbonic acid, protoxide of azote. 7 The smell of all the others is insupport- able, and frequently characteristic. 8. Gases very solulle in -water, namely, of which water dissolves more than 30 times its volume, at ordinary pressure and temperature. Fluoric acid, muriatic, fluosilicic, nitrous, sul- phurous, and ammonia. 9. Gases solulle in alkaline solutions. Acids, nitrous, sulphurous, muriatic, fluoboric, hy- driodic, fluosilicic, chlorine, carbonic, chlo- rocarbonous ; and the two oxides of chlorine, sulphuretted hydrogen, telluretted hydrogen, and ammonia. 10. Alkaline gases. Ammonia and potas- suretted hydrogen. Such is a general outline of the charac- teristics of the gases. The great problem which now presents itself is, to determine by experiments the nature of any single gas, or gaseous mixture, which may come before us. I. We first fill a little glass tube with it, and expose it to the action of a lighted taper. If it inflames, it is one of the 1 1 above enumerated, and must be discriminated by the following methods. 1. If it takes fire spontaneously on contact with air, producing a very acid matter, it is phosphuretted hydrogen. Subphosphuretted hydrogen, or the bihydroguret of phosphorus, does not spontaneously inflame. 2. If water be capable of decomposing it, and transforming it suddenly into hydrogen gas and alkali, which we can easily ascertain by transferring the test tube, filled with it, from the mercurial trough, to a glass contain- ing water, it is potassuretted hydrogen. I found in my experiments on the production of potassium, by passing pure potash over ignited iron turnings, of which some account was published in 1809, that potassuretted hydrogen spontaneously inflamed. M. Sementini has made the same observation. 3. If it has a nauseous odour, is insoluble in water, leaves on the sides of the test tube in which we burn it a chestnut-brown deposite, like hydruret of arsenic, and if, after agitation with the quarter of its volume of aqueous chlorine, a liquid is formed, from which sul- phuretted hydrogen precipitates yellow flocculi, it is arsenuretted hydrogen gas. GAS 491 GAS 4. If it has a strong smell of garlic or phosphorus, if it does not inflame sponta- neously, if the product of its combustion strongly reddens litmus, and if, on agitation with an excess of aqueous chlorine, a liquor results, which, after evaporation, leaves a very sour syrupy residuum, it is subphosphuretted 5. If it has no smell, or but a faint one, and if it be capable of condensing one-half its volume of oxygen in the explosive eudiometer, it is hydrogen. 6. If it has a faint smell, be capable of con- densing in the explosive eudiometer one-half of its volume of oxygen, and of producing a volume of carbonic acid equal to its own, which is ascertained by absorbing it with aqueous potash, it is carbonous oxide. 7- If it has a faint smell, if one of the products of combustion is carbonic acid, and if the quantity of oxygen which it condenses by the explosive eudiometer, corresponds to twice or thrice its volume, then it is either subcarlurcttcd or carburetted hydrogen. 8. If it diffuses the odour of rotten eggs, if it blackens solutions of lead, if it leaves ade- posite of sulphur, when we burn it, in the test tube, and if it be absorbable by potash, it is sulphuretted hydrogen. 9. If it has a fetid odour, approaching to that of sulphuretted hydrogen, if it is absorb- able by potash, if it is soluble in water, if it forms with it a liquid, which, on exposure to air, lets fall a brown pulverulent hydruret of tellurium ; and lastly, if on agitation with an excess of aqueous chlorine, there results a mu- riate of tellurium, yielding a white precipitate with alkalis, and a black with the hydro- sulphurets, it is tellurctted hydrogen. 10. Prussine is known by its offensive and very peculiar smell, and its burning with a purple flame. II. If the gas be non-inflammable, but ab- sorbable by an alkaline solution, it will be one of the 13 following : muriatic acid, fluo- boric, fluosilicic, hydriodic, sulphurous, ni- trous, chlorocarbonous, carbonic ; or chlorine, the oxides of chlorine, prussine, or ammonia. The first four, being the only gases which produce white vapours with atmospheric air, from their strong affinity for water, are thus easily distinguishable from all others. The Jluosilicic gas is recognised by the separation of silica, in white flocculi, by means of water ; and hydriodic gas, because chlorine renders it violet, with the precipitation of iodine. Muriatic acid gas, from its forming with solution of silver a white precipitate insoluble in acids, but very soluble in ammonia, and from its yielding with oxide of manganese a portion of chlorine. Fluoloric gas, by the very dense vapours which it exhales, and by its instantly blackening paper plunged into it. Nitrous acid gas is distinguished by its red colour. Protoxide of chlorine, because it is of a lively greenish-yellow hue, because it exercises no action on mercury at ordinary temperatures, and because, on bringing ig- nited iron or glass in contact with it, it is decomposed with explosion into oxygen and chlorine. Deutoxide of chlorine is of a still brighter yellowish-green than the preceding, and has a peculiar aromatic smell. It does not red- den, but blanches vegetable blues. At 212 it explodes, evolving oxygen and chlorine. Chlorine is distinguished by its fainter yellow- ish-green colour, by its suffering no change on being heated, by its destroying colours, and by its rapid combination with mercury at com- mon temperatures. Sulphurous acid by its smell of burning sulphur. Ammonia by its odour, alkaline properties, and the dense white vapours it forms with gaseous acids. Chloro- carbonous gas is converted by a very small quantity of water into aqueous muriatic acid, and carbonic acid, which rests above. Zinc or antimony, aided by heat, resolves it into carbonous oxide gas, while a solid metallic chloride is formed. With the oxides of the same metals it forms chlorides, and carbonic acid, while in each case the quantity of gaseous oxide of carbon, and carbonic acid disengaged, is equal to the volume of chlorocarbonous gas operated on. Carbonic acid gas is colourless, and void of smell, while all the other gases absorbable by the alkalis have a strong odour. It hardly reddens even very dilute tincture of litmus; it gives a white cloud with lime water, from which a precipitate falls, soluble with effervescence in vinegar. III. If, finally, the gas be neither inflammable, nor capable of being absorbed by a solution of potash, it will be oxygen, azote, protoxide of azote, or deutoxide of azote. Oxygen can be mistaken only for the protoxide of azote. The property it possesses of rekindling the expir- ing wick of a taper, distinguishes it from the two other gases. They are moreover charac- terized, 1st, Because oxygen is void of taste, and capable of condensing in the explosive eudiometer twice its volume of hydrogen gas ; the protoxide of azote, because it has a sweet taste, is soluble in a little less than half its volume of cold water, and because when detonated with its own volume of hydrogen, we obtain a residuum, containing much azote. The two other gases are distinguished thus : Deutoxide of azote is colourless, and when placed in contact with atmospherical air or oxygen, it becomes red, passing to the state of nitrous acid vapour. Azote is void of colour, smell, and taste, extinguishes combustibles, experiences no change on contact with air, and produces no cloud with lime water. GAS 492 GAS Under the different gases, the reader will find their discriminating characters minutely detailed. We shall conclude this article with a method of solving readily an intricate and common problem in gaseous analysis, for which no direct problem has I believe^ been yet offered. Allusion has been made to it in treating of coal gas, and the plan pointed out in a popular way. Analytical problem. In a mixture consti- tuted like purified coal gas, of three inflam- mable gases, such as oletiant gas, carburetted hydrogen, and carbonous oxide, inseparable by ordinary chemical means, to determine di- rectly the quantity of each. 1 . By the rule given at the commencement of the present article Gas, find from the speci- fic gravity of the mixed gases the proportion of the light carburetted hydrogen. The remain- der is the bulk of the other two gases. Deto- nate 100 measures of the mixed gas with ex- cess of oxygen hi an explosive eudiometer. Observe the change of volume, and ascertain the expenditure of oxygen. Of the oxygen consumed, allow two volumes for every vo- lume of light carburetted hydrogen, sp gr. 0.555, previously found, by the hydrostatic rule, to be present. The remaining volumes of oxygen have gone to the combustion of heavy carburetted hydrogen, or olefiant gas and car- bonous oxide. Then, Let m measure of oxygen equivalent to 1 of first gas, n = do. do. to 1 of second gas, p = measures of oxygen actually con- sumed, 100 or s = volume of mixture of these two x =. volume of first gas, s x volume of second gas, EXAMPLES. 1st, 100 measures of purified coal gas were found, by the hydrostatic problem, to contain 76 of subcarburetted hydrogen ; and exploded in the eudiometer they were found to consume 187 cubic inches of oxygen. By condensing with potash the carbonic acid formed, we learn the volume of residuary oxygen. But the solution of the problem is otherwise indepen- dent of the quantity of carbonic acid gene- rated in the present experiment We see from the table of the gases, that 1 volume of olefiant gas is equivalent to 3 of oxygen ; and 1 volume carbonous oxide to one-half volume oxygen. Therefore, deducting for the 76 of subcarbon- ate, 152 measures of oxygen, the remaining 35 have gone to the 24 measures of the two denser gases. Hence Olefianj gas, or x = 35 ( - -H> = 9-2 And 24 9-2 = 14-8 = the carbonous oxide. 2dj 100 measures of a mixture of olefiant gas, and carbonous oxide, take 236 of oxy- gen : What is the proportion of olefiant gas ? x or olefiant = 236 ( - 5 2 X 5 100) =74-4, consequently 25-6 are carbonous oxide. This problem is applicable to every mixture of two inflammable gases. The hydrostatic problem I have been accustomed for years to apply to mixtures of two gases, whose specific gravities are considerably different, as carbonic acid and atmospheric air, and with a delicate balance, and globe containing 100 cubic inches, it gives a good accordance with chemical expe- riment. I employed this method for verification, in examining the air extracted from the lungs of the criminal's dead body, galvanized at Glas- gow in Nov. 1818. Generally, if we wish to get an approximate knowledge of the proportion of two gases in a mixture, we may adopt the following plan. Poise the exhausted globe or flask at one arm of a delicate balance. Then connect its stop- cock with the gasometer, bladder, or jar, con- taining the gaseous mixture. Introduce an unmeasured quantity, great or small, relative to the capacity of the globe ; for it is not ne- cessary that the density of the air in the globe should be equal to that of the atmosphere. In fact, it may happen, that the whole quantity of the gaseous mixture may not be equal to more than one-third, one-half, or three-fourths of the capacity of the globe. For instance, in the case of the criminal, I took a globe, capa- ble of receiving greatly more than the aerial contents of his lungs. An unknown quantity of the mixed gases being now in the globe, we suspend it at the balance, and note the increase of weight. We then open the stop-cock, and allow the atmosphere to enter, till an equili- brium of pressure ensues. The additional weight occasioned by the atmospheric air must be converted into bulk, at the rate of 30.519 gr. for 100 cubic inches. Deducting this bulk from the known capacity of our globe or flask, leaves a remainder, which is the vo- lume of the gaseous mixture first introduced : knowing its weight and volume, we infer its specific gravity ; and from its specific gravity, by the hydrostatic problem, we deduce the proportion of each gas in the. mixture. IV. Of the method of determining the spe- cific gravity of gases, and of the modification of their volume from variation of pressure and temperature. The specific gravity of a gas is the weight of a certain volume of it, compared to the same volume of ak or water. Air is now assumed as the standard for gases, as water is for liquids ; and the same hydrostatic method GAS 493 GAS is applicable to both elastic and inelastic fluids. We determine the specific gravity of a gas with an air-pump, balance, and globe or flask, having a stop-cock attached to its orifice. We proceed thus : We poise the globe at the end of a balance, with its stop-cock open : we next exhaust it, and weigh it in that state. The difference of the two weighings is the apparent weight of the volume of atmospheric air with- drawn from it. We verify that first estimate, by opening the stop-cock, and noting the in- crease of weight occasioned by the ingress of the air. Having again exhausted, exactly to the same degree, by the mercurial gauge, as before, we poise. This gives us, for the third time, the weight of air contained by the globe. The mean of the three trials is to be taken. We now attach it, by the screw of the stop-cock, to a gasometer or jar, containing gas desiccated by muriate of lime over mercury, and opening the communication, allow the ah- to enter till an equilibrium of pressure with the atmosphere is established. In this stage of the operation, we must avoid grasping the globe with our hands, and we must see that the mercury in the inside and outside of the jar stands truly on a level. On re-suspending the globe at die ba- lance, we find the weight of the included gas, which being divided by the weight of the air formerly determined, gives a quotient, which is the specific gravity of the gas in question. When the utmost precision is required, we should again exhaust the globe, again poise it, and filling it with the gas, again ascertain its sp. gravity under the bulk of the globe. Even a third repetition is sometimes necessary to se- cure final accuracy. We should always termi. nate the operations by a new weighing of the atmospheric air, lest its temperature or pressure may have changed during the course of the ex- periments. It is obvious, that this method differs in no respect from that practised long ago by the Hon. Robert Boyle, and by Sir Charles Blagden, (See ALCOHOL), with li- quids, and is that which, I suppose, every public teacher of physics, like myself, explains and exhibits annually to his pupils. With re- gard to liquids, it is necessary to bring them to a standard temperature, which in this country is 60 F. But, as the comparison of gases with air is always made at the instant, our only care need be, that the gas and atmosphere are in the same state as to temperature and moisture, and that the equilibrium of pressure be ensured to the gas by bringing the liquid which con- fines it to a level on the inside and outside of the jar. If the gases- stand over water, it is desirable to weigh them in somewhat cold weather, when the thermometer is, for example, at 40 ; for then the quantity of aqueous vapour they con- tain is exceedingly small. Or otherwise, we should place the atmospheric air we use for the standard of comparison in the very same cir- cumstances, over water, at 60 for instance ; and then with regard to those gases whose den- sity differs little from that of the atmosphere, no correction for vapour need be considered. From the experiments of M. de Saussure, and those of MM. Clement and Desormes, we leam, that the same bulk of different gases standing over water gives out, on being trans- mitted over dry muriate of lime, the same quantity of that liquid ; which, for 100 cubic inches, is, by the first philosopher, 0-35 of a grain troy at 57 F-, and by the second 0-230 at 54. We shall, perhaps, not err, by con- sidering the weight to be one-third of a grain at'60. Now, for 1 00 cubic inches of hydro- gen, which in the dry state weigh only 2-118, one-third of a grain is nearly one-seventh of the whole, equivalent to 14 cubic inches of dry gas. But for oxygen, of which 100 cubic inches weigh nearly 34 grains, one-third of a grain forms only 1-1 10th of the whole. The quantity of moisture present in air or gas, at any temperature, may indeed be directly determined from my table of the elasticity of aqueous vapour. If we multiply 14.68, which is the weight in grains of 100 cubic inches of steam, by the number 0.516 opposite 60<> m m y table, we shall have a product, which, divided by 30, will give a quotient n the weight of aqueous vapour in 100 inches of any gas standing over water at the given temperature. e oO We have seen, in treating of caloric, that all gaseous matter changes its volume by one 480th part, for the variation of 1 of Fahren- heit's thermometer, departing from the tem- perature of 32. This quantity is in decimals = 0-0020833. The bulk of a gas being inversely as the pressure, it will necessarily increase as the barometer falls, and decrease as it rises. Hence, to reduce the volume of a gas at any pressure, to what it would be under the mean pressure of 30 inches of mercury ; multiply the volume by the particular barometrical pressure, and divide the product by 30 ; the quotient is the true volume. If the gas be contained in a vessel over mercury, so that the liquid metal stands in the inside of the tube higher than on the outside, it is evident that the gas will be compressed by a less weight than the ambient atmosphere, in proportion to the difference of the mercurial levels. If that difference were 10 inches, then one-third of the incumbent pressure would be counter- balanced, and the gas would become bulkier by one- third. Hence, we must subtract this difference of mercurial levels from the baro- metric altitude at the instant, and use this reduced number or remainder, as the proper multiplier in the above rule. Instead of re- ducing the volume of a gas to what it would be under a mean pressure of 30 inches, it is often desirable to reduce it to another baro- metrical height, which existed perhaps at the commencement of the experimental investiga- GAS 494 GAS tion. Thus, in applying the eudiometer by slow combustion of phosphorus, we must wait for 24 hours till the experiment be finished. But in that period, and in our fickle climate, the mercury of the barometer may have moved an inch or more. The general principle, that the volume is inversely as the pressure, mea- sured by the length of the mercurial column, affords the following simple rule: Multiply the bulk of the gas by the existing height of the barometer, and divide the product by the original height, the quotient is its bulk as at the commencement of the experiment. The baro- metric pressure is estimated by the inches on its scale, minus the difference of mercurial levels in the pneumatic apparatus. By bring- ing the two surfaces to one horizontal plane, this correction vanishes. The facility of doing so with my eudiometer is one of its chief ad- vantages. If we are operating in the water pneumatic cistern, we can in general bring the two surfaces to a level. If not, we must allow one inch of mercurial pressure for 13-6 inches of water; and, of course, l-10th of a barome- trical inch for every inch and third of water. From the researches of Mr. Daniell and Mr. Faraday, it appears that gases are more readily preserved from admixture with atmo- spheric air, when kept in glass vessels in verted over water, than over mercury. The filtration, in such cases, takes place along the surface of the glass, and not through the pores of the mercury. In this way, air insinuates itself into barometers, occasioning a slow and progressive deterioration of these instruments. The only method of preventing this passage of air, is to bring the mercury into intimate contact with the mouth of the tube, by attaching to its rim at the blowpipe a slender ring of platinum. When the glass, thus armed, is immersed in mercury, the effect is soon perceived ; for, instead of any depression being visible around it, the mercury may be lifted by it, consi- derably above its proper level on the outside, where Mr. Daniell had welded his riband of platinum, about one-third of an inch broad. Intimate contact, in fact, is thus secured be- tween the mercury and the mouth of the tube, so that no air can pass between them.- M. Gay Lussac contrived a very ingenious apparatus, to determine the change of volume which an absolutely dry gas undergoes, when water is admitted to it, in minutely successive portions, till it (or the space it occupies) be- comes saturated. He deduced from these accurate experiments the following formula, whose results coincide perfectly with those deducible from Mr. Dalton's and my expe- riments on the elastic force of aqueous va. pour. When a perfectly dry gas is admitted to moisture, its volume, i>, augments, and be- comes - ; in which = the barometric P f altitude, in inches, and/= the elastic force of steam at the given temperature. Hence, 100 cubic inches of dry air, weighing 30-511) grains, become 101 -755 .when transferred over water at 60. Therefore, 100 cubic inches of such aeriform matter, standing in a jar on the hydro-pneumatic trough, must consist of, 98-28 cubic inches dry air = 29-9900 gr. 1-72 aqueous vapour = 0-2525 gr. Weight of 100 cubic inches of air, over water at 60 = 30-2425 For hydrogen we shall have, 98-28 inches dry gas = 2-0815? gr. 1-72 aqueous vapour = 0-2525 Weight of 100 cubic inches moist gas ..,. >A. . 2-3340? Hence its sp. gr. compared to that of dry air, will be -^^l = 0-7648, and com- 2 33407 pared to moist air = ~jg- = 0-0772. For chlorine we shall have (making the sp. gr. of the dry gas = 2-5), 98-28 cubic inches . . = ?4.985? l-?2 aqueous vapour . . = 0-2525 Weight of 100 cu. in. of moist chl. = ?5-2382 Hence, its sp. gr. compared to that of dry air, will be = 75-2382 30-519 = 2-2465, and com- . . 75-2382 _ Amo pared to moist air ' 2-4878. Now, the first is almost the density assigned long ago by MM. Gay Lussac and Thenard ; on which, if we make the correction for aque- ous vapour present in it, on account of this gas never being collected over mercury, we shall have its true specific grav. = 2-5. Sir H. Davy brought out a number still nearer 2-5 than that of M. Gay Lussac. His chlorine was probably compared with air somewhat moist, and may therefore be considered as readily reducible, by a minute correction, to 2-5. The reason assigned by Dr. Thomson (Annals for Sept. and Oct. 1820) for the former erroneous estimates of the sp. gravity of that gas, cannot surely apply to the two first chemists of the age ; namely, that the chlorine they prepared as the standard of comparison was impure. I think the true reason is that which I have now given. For olefiant and carbonic oxide gases, we shall have, ,98-28 cubic inches . . = 29-1564 1-72 vapour . . . = 0-2525 Weight of 100 cub. in. of moist gas = 29-4089 Hence, its sp. gr. compared to that of dry air, will be = = 9636, and to moist GEH 495 GEO GASES (LIQUEFACTION or). See ACID (CARBONIC). ACID(SULPHUROUS), CHLO- RINE, CYANOGEN, &c. GASTRIC JUICE, is separated by glands placed between the membranes which line the stomach ; and from these it is emitted into the stomach itself. From various experiments it follows : 1. That the gastric juice reduces the ali- ments into an uniform magma, even out of the body, and in vitro ; and that it acts in the same manner on the stomach after death; which proves that its effect is chemical, and almost independent of vitality. 2. That the gastric juice effects the solution of the aliments included hi tubes of metal, and consequently defended from any trituration. 3. That though there is no trituration in membranous stomachs, this action powerfully assists the effect of the digestive juices in animals with a muscular stomach, such as ducks, geese, pigeons, &c. Some of these animals, bred up with sufficient care that they might not swallow stones, have nevertheless broken spheres and tubes of metal, blunted lancets, and rounded pieces of glass, which were introduced into their stomachs. Spallanzani has ascertained, that flesh, included in spheres sufficiently strong to resist the mus- cular action, was completely digested. 4. That gastric juice acts by its solvent power, and not as a ferment ; because the ordinary and na- tural digestion is attended with no disengage- ment of air, or inflation, or heat, or. in a' word, with any other of the phenomena of fermentation. GAY-LUSSITE. A new mineral, found by M. Boussingault in great abundance, at Lagunilla, a small Indian village, to the south-west of Merida. It is in transparent and colourless crystals (very imperfect in form), or sometimes greyish and semi-transparent, with a dull surface. They cause double refraction. Sp.gr. 1-93 to 1-95. By heat, they decre- pitate, become opaque, and yield much water. Before the blowpipe a fragment fuses into a globule, which instantly becomes infusible, and is then alkaline to the taste. It dissolves in small quantity in water, yielding a solution which reddens turmeric paper,and is precipitated by oxalic acid. It consists, in 100 parts, of carbonic acid, 28-66; soda, 20-44 ; lime, 17-7; alumina, 1 ; water, 32-2 ; or of an atom of carbonate of soda, an atom carbonate of lime, and 11 atoms of water. Ann. de Chim. xxxi. 270. GEHLENITE. A mineral substance, allied to Vesuvian. Its colours are oh" ve-green, leek- green, green of other shades, and brown. It occurs crystallized in rectangular four-sided prisms, which are so short as to appear tables. Lustre glistening, often dull. Cleavage imper- fect, but three-fold rectangular. Fracture fine splintery. Translucent on the edges. Rather easily frangible. Harder than felspar, but softer than quartz. Sp. gr. 2-93. It melts before the blowpipe into a brownish-yellow transparent glass. It is found along with calcareous spar in the valley of Fassa in the Tyrol. Its constituents are, lime 35-5, silica 29-64, alumina 24-8, oxide of iron 6-56, vo- latile matter 3-3. GELATIN, GELLY, or JELLY, an animal substance, soluble in water, capable of assuming a well-known elastic or tremulous consistence, by cooling, when the water is not too abundant, and liquefiable again by in- creasing its temperature. This last property distinguishes it from albumen, which becomes consistent by heat. It is precipitated in an insoluble form by tannin ; and it is this action of tannin on gelatin that is the foun- dation of the art of tanning leather. See GLUE. According to the analysis of MM. Gay Lussac and Thenard, gelatin is composed of Carbon Oxygen Hydrogen Azote 47-881 27-207 7-914 16-998 100-000 GEMS. This word is used to denote such stones as are considered by mankind as pre- cious. These are, the diamond, the ruby, the sapphire, the topaz, the chrysolite, the beryl, the emerald, the hyacinth, the amethyst, the garnet, the tourmalin, the opal ; and to these may be added, rock crystal, the finer flints or pebbles, the cat's eye, the oculus mundi, or hydrophanes, the chalcedony, the moon-stone, the onyx, the cornelian, the sardonyx, agates, and the Labrador-stone ; for which, consult the several articles respectively. GEODES. A kind of aetites, the hollow of which, instead of a nodule, contains only loose earth, and is commonly lined with crystals. GEOGNOSY. See GEOLOGY. GEOLOGY. A description of the struc- ture of the earth. This study may be divided, like most others, into two parts ; observation and theory. By the first we learn the relative positions of the great rocky or mineral aggre- gates that compose the crust of our globe ; through the second, we endeavour to penetrate into the causes of these collocations. A valuable work was some time since published, comprehending a view of both parts of the subject, by Mr. Greenough, to which I refer my readers for much instruction, communi- cated in a very lively manner. Very recently the world has been favoured with the first part of an excellent view of this science by Messrs. Conybeare and Phillips, in their '< Outlines of the Geology of England and Wales ;" from which work, the following brief sketch of the subject is taken : The GEO 496 GEO Traite ile Gcognosle of D'Aubuisson bears a high character on the continent. He is a liberal Wernerian. WERNER'S Table of the different Mountain Rocks, from Jameson. CLASS I. "Primitive rocks. 1. Granite. 2. Gneiss. 3. Mica-slate. 4. Clay-slate. 5. Primitive limestone. 6. Primitive trap. 7- Serpentine. 8. Porphyry. 9. Syenite. 10. Topaz rock. 11. Quartz rock. 12. Primitive flinty-slate. 13. Primitive gypsum. 14. White stone. CLASS II. Transition rocks. 1. Transition limestone. 2. Transition trap. 3. Greywacke. 4. Transition flinty-slate. 5. Transition gypsum. CLASS III. Floctz rocks. 1. Old red sandstone, or first sandstone formation. 2. First or oldest floetz limestone. 3. First or oldest floetz gypsum. 4. Second or variegated sandstone formation. 5. Second floetz gypsum. 6. Second floetz limestone. 7. Third floetz limestone. 8. Rock-salt formation. 9. Chalk formation. 10. Floetz-trap formation. 11. Independent coal formation. 12. Newest floetz trap formation. CLASS IV. Alluvial rock$. 1. Peat. 2. Sand and gravel. 3. Loam. 4. Bog-iron ore. -5. Nagelfluh. 6. Calc-tuff. 7 Calc sinter. CLASS V. Volcanic rocks. * Pseudo- volcanic rocks. 1. Burnt clay. 2. Porcelain jasper. 3. Earth slag. 4. Columnar clay ironstone. 5. Polier, or polishing slate. * * True volcanic rocks. 1. Ejected stones and ashes. 2. Different kinds of lava. 3. The matter of muddy eruptions. The primitive rocks lie undermost, and never contain any traces of organized beings imbedded in them. The transition rocks contain comparatively few organic remains, and approach more nearly to the chemical structure of the primitive than the mechanical of the secondary rocks. As these transition rocks were taken by Werner from among those which in his general arrangement were called secondary, the formation of that class made it necessary to abandon the latter term. To denote the mineral masses reposing on his transition series, he accordingly employed the term floetz rocks, from the idea that they were generally stratified in planes nearly hori- zontal, while those of the older strata were inclined to the horizon at considerable angles. But this holds good with regard to the struc- ture of those countries only which are com- paratively low : in the Jura chain, and on the borders of the Alps and Pyrenees, Werner's floetz formations are highly inclined. Should we therefore persist in the use of this term, says Mr. Conybeare, we must prepare our- selves to speak of vertical beds of floetz, (i. e. horizontal), limestone, &c. As the inquiries of geologists extended the knowledge of the various formations, Werner, or his disciples, found it necessary to subdivide the bulky class of floetz rocks into floetz and newest floetz, thus completing a fourfold enumeration. Some writers have bestowed the term tertiary on the newest floetz rocks of Werner. The following synoptical view of geological arrangement is given by the Rev. Mr. Conybeare. GEO 497 GEO CHARACTER. PROPOSED NAMES. WERNERIAX NAMES. OTHER WRITERS. 1. Formations (chiefly of sand and clay) above the chalk. Superior order. Newest floetz class. Tertiary class. 2. Comprising, a. Chalk. b. Sands and clays, le- neatfi the chalk. c. Calcareous freestones (oolites} and argilla- Supermedial order. Floetz class. Secondary class. ceous beds. d. New red sandstone, con- glomerate, and mag- ncsian limestone. 3. Carboniferous rocks, com- prising, a. Coal measures. b. Carboniferous limestone. c. Old red sandstone. Medial order. Sometimes referred to the preceding, sometimes to the succeeding class, by writers of these schools; very often the coal measures are referred to the former, the subjacent limestone and sandstone to the latter. 4. Roofing state, &c. &c. Submedial order. Transition class. Intermediate class. 5. Mica slate, gneiss, granite^ &c. Inferior order. Primitive class. Primitive class. In all these formations, from the lowest to the highest, we find a repetition of rocks and beds of similar chemical composition ; i. e. siliceous, argillaceous, and calcareous, but with a considerable difference in texture ; those in the lowest formations being compact and often crystalline, while those in the highest and most recent are loose and earthy. These repetitions form what, the Wernerians call formation suites. We may mention, 1st, The limestone suite. This exhibits, in the inferior or primitive order, crystalline marbles; in the two next, or transition and carboniferous orders, compact and subcrys- talline limestones (Derbyshire limestone) ; in the supermedial or floetz order, less compact limestone (lias), calcareous freestone (Portland and Bath stone), and chalk ; in the superior or newest floetz order, loose earthy limestones. 2d, The argillaceous suite presents the following gradations ; clay-slate, shale of the coal-measures, shale of the lias, clays alter- nating in the oolite series, and that of the sand beneath the chalk; and, lastly, clays above the chalk. 3d, The siliceous suite may (since many of the sandstones of which it consists present evident traces of felspar and abundance of mica, as well as grains of quartz, and since mica is more or less present in every bed of sand), perhaps deserve to have granite placed at its head, as its several members may pos- sibly have been derived from the detritus of that rock : it may be continued thus ; quartz rock and transition sandstone, old red sand- stone, millstone-grit, and coal-grits, new red sandstone, sand and sandstone beneath the chalk, and above the chalk. In all these instances a regular diminution in the degree of consolidation may be perceived in ascending the series. We noticed before, that the remains of vegetables and animals are confined to the secondary formations. We have now to add, that they are not irregularly dispersed through- out the whole series of these formations, but disposed as it were in families, each formation containing an association of species peculiar in many instances to itself, widely differing from those of other formations, and accom- panying it throughout its whole course ; so that at two distinct points on the line of the same formation, we are sure of meeting the same general assemblage of fossil remains. It will serve to exemplify the laws which have been stated, if the observer's attention is di- rected to two of the most prominent formations of this island; namely, the chalk and the limestone which underlie the coal in North- umberland, Derbyshire, South Wales, and Somerset Now if he examines a collection of fossils from the chalk of Flamborough-Head, or from that of Dover-CJfffs, or, it may be added, from Poland or "Paris, he will find K K GEO 498 GEO eight or nine species out of ten the same ; he will observe the same echinites associated with the same shells; nearly one-half of these echinites he will perceive to belong to divisions of that family unknown in a recent state, and indeed in any other fossil bed except the chalk. If he next proceeds to inspect parcels of fossils from the carboniferous limestone, he will in the same manner find them to agree with each other, from whichever of the above localities they may have been brought ; that is, he will find the same corals, the same encrinites, the same productse, terebratulae, spiriferfe, &c. But, lastly, if he compares the collection from the chalk with that from the mountain lime, he will not find one single instance of specific agreement, and in very few instances any thing that could deceive even an unpractised eye, by the superficial resemblance of such an agreement. If we cast a rapid view over the phenomena of this distribution, the subject must appear to present some of the most singular problems which can engage the attention of the inquirer into nature. First we have a foundation of primitive rocks destitute of these organic re- mains ; in the next succeeding series (that of transition), corals, encrinites, and testacea, different however from those now known, ap- pear at first sparingly. The fossil remains of the carboniferous limestone are nearly of the same nature with those in the transition rocks, but more abundant ; the coal-measures (coal strata), however, themselves, which repose on this limestone, present scarcely a single shell or coral ; but, on the contrary, abound with vegetable remains, ferns, flags, reeds of un- known species, and large trunks of succulent plants, strangers to the present globe. Upon the coal rest beds again containing marine re- mains (the magnesian limestone), then a long interval (of new red sandstone) intervenes, destitute almost, if not entirely, of organic re- mains, preparing the way, as it were, for a new order of things. This order commences in the lias, and is continued in the oolites, green and iron sands, and chalk. All these beds contain corals, encrinites, echinites, testa- cea, Crustacea, vertebral fishes, and marine oviparous quadrupeds, yet widely distin- guished from the families contained in the lower beds of the transition and carboniferous class, and particularly distinguished among themselves, according to the bed which they occupy. Hitherto the remains are always petrified, z. e. impregnated with the mineral substance in which they are imbedded. But, lastly, in the strata which cover the chalk, we find the shells merely preserved, and in such a state, that when the* clay or sand in which they lie is washed off, they might appear to be recent, had they not lost their colour, and become more brittle. Here we find beds of marine shells alternating with others peculiar to fresh water, so that they seem to have been deposited by reciprocating inundations of fresh and salt water. In the highest of the regular strata, the crag, we at length can find an identity with the shells at present existing on the same coast ; and, lastly, over all these strata indiscriminately there is spread a cover- ing of gravel (seemingly formed by the action of a deluge, which has detached and rounded by attrition fragments of the rocks over which it swept), containing the remains of numerous land quadrupeds, many of them of unknown genera or species, (the mastodon, and the fossil species of elephant, or mammoth, bear, rhino- ceros, and elk), mingled with others (hyamas, &c.) equally strangers to the climates where they are now found, yet associated with many at present occupying the same countries. Another class of substances imbedded in the secondary strata, and throwing light on the convulsions amidst which they have been formed, are the pebbles, or rolled fragments of rocks, older than themselves, which they are often found to contain. Thus the lower beds of the supermedial order (namely, the conglomerate rocks of the new red sandstone) contain in great abundance rolled fragments of the carboniferous limestone belonging to the class next below it (the medial order), as well as of many still older rocks ; being in fact only a consolidated mass of gravel, composed of debris of these rocks. The necessary inferences from this fact are, first, The rock whence the fragments were de- rived must have been consolidated, and, sub- sequently to that consolidation, have been ex- posed to the mechanical violence (probably the action of agitated waters) which tore from it these masses, and rounded them by attrition, before the rock in which these fragments are now imbedded was formed ; and, secondly, Since loose gravel beds (and such must have been the original form of these, though now consolidated into conglomerate rocks) cannot be accumulated to any extent from the action of gravity on a highly inclined plane, we are sure, when we find such beds, as we often do in nearly vertical strata, that this cannot have been their original position, but is one into which they have been forced by convulsions which have dislocated them subsequently to their consolidation. These consolidated gravel beds are called conglomerates, breccias, or pudding stones ; we find them among the transition rock, in the old red sandstone, in the millstone-grits and coal-grits, in the lower members of the new red sandstone, in the sand strata beneath the chalk, and in the gravel beds associated with the plastic clay, and in- terposed between the chalk and great London clay. From the occurrence of the marine remains lately noticed, occupying, as they do, rocks spread over two-thirds of the surface of every part of our continents which have been ex- plored, and rising to the highest situations, GEO GEO even to the loftiest summits of the Pyrenees, and still more elevated points on the Andes, it is an inevitable inference, that the greater part of those continents have not only been covered by, but have been formed of materials collected within the bosom of the ocean ; that we inhabit countries which we may truly call facias ex cequore terras. The great and fun- damental problem, therefore, of theoretical geology, is obviously to assign adequate causes for the change of level in this ocean, which has permitted these masses, which once formed the bottom of its channel, to rise in hills and moun- tains above its waves. The causes which it is possible to imagine are reducible to two general classes. First, The decrease of the absolute quantity of water. This must have resulted from causes entirely chemical, namely, the decomposition of some portion of the water, its constituents entering into new forms of combination; and its fixation in the rocks formed beneath it. It is probable that these causes have operated to some degree, but it seems impossible to ascribe to them the very great difference of level for which we have to account. The second class of possible causes is en- tirely mechanical ; those, namely, which may have produced a change of relative level with- out any diminution of absolute quantity in the waters. The causes of this kind which have been proposed are, first, The absorption of the wa- ters into a supposed central cavity ; but the now ascertained density of the earth (being greater than that which would result from an entirely solid sphere of equal magnitude of the most compact known rock) renders the existence of any such cavity very doubtful. Secondly, A writer in the Journal of the Royal Institution, voL ii. has proposed the very ingenious hypothesis, that a change of temperature of a few degrees will, from the unequal expansibility of die materials of land and water, sufficiently account for this change of level. Thirdly, It has been ascribed to violent convulsions, which have either heaved up the present continents, or, which amounts to the same thing (as the same relative change must have taken place in either view), depressed the present channel of the ocean. If the vio- lent elevation of the continent, or depression of the channel of the ocean, supposed in the last mentioned hypothesis, really took place, it must have left traces in the disturbed, con- torted, and highly inclined position of the strata; and these disturbances must be the greatest where the change of level has been the greatest, i. e. in the neighbourhood of the loftiest mountains. Now this is actually the case. In support of the hypothesis which ascribes an important part to volcanic agency in mo- difying the surface of our planet, the follow- ing, at least plausible, arguments might be adduced. 1. It must be kept in view, that the object is to assign an adequate cause for the un- doubted fact of the emergence of the loftiest mountains of the present continent ; and that when so mighty an effect is to be accounted for, the mind must be prepared to admit, without being startled, causes of a force and energy greatly exceeding those with which we are acquainted from actual observation. 2. The broken and disturbed state, and in- clined position of the strata composing those continents., many of which must have been at the time of their original formation horizontal, indicate, as we have seen, that one at least of the causes operating to effect this great change of relative level between the land and waters, was the elevation of the former by mechanical force. 3. The only agent with which we are ac- quainted, whose operation bears any analogy to the effects above specified, is the volcanic energy, which still occasionally forms new islands, and elevates new mountains. 4. Although these effects are now indeed partial and limited, yet there is certain proof that volcanic agency has formerly been much more active; the extinct volcanoes of the Rhine, Hungary, and Auvergne, as well as those which occupy so large a portion of Italy, where only one remains in activity, concur in proving, that at present we experience only the expiring efforts, as it were, of those gigantic powers which have once ravaged the face of nature. 5. If to this certain proof of the greater pre- valence of volcanic convulsions in earlier, but still comparatively recent, periods of the his- tory of our planet, we add the presumption that the trap rocks (so singularly intruded among the regular strata, and producing, where they traverse those strata, so precisely the effects of heat acting under compression, and so different in all their phenomena from formations decidedly aqueous), were of volcanic origin, we shall find that scarcely a country exists, which has not been a prey to the ra- vages of this powerful principle. If, with many of the best geological observers, (Dr. M'Culloch, Von Buch, Necker, &c.) we in- cline to extend the same conclusions to granitic , rocks, a mass of volcanic power, clearly ade- quate to all the required effects, is provided. 6. The question will undoubtedly present itself, what is the source of volcanic action ? and sufficient proof exists, that this source is deeply seated beneath the lowest rocks with which our examination of the earth's surface makes us acquainted ; for, in Auvergne, the lavas have evidently been erupted from beneath the primitive rocks. 7. The very important recent discoveries with regard to the increased temperature no- ticed in descending deep mines, &c. by Messrs. K K 2 GEO 500 GEO Fox and Fourrier, will, if confirmed by further examination, prove, that some great source of heat exists beneath the earth's crust. 3. A degree of presumption may be thought to arise from these considerations, that the crust of the earth rests on a heated nucleus, the true source of volcanic energy. If this nucleus be in a fluid or viscous state, its un- dulations would readily account for the con- vulsions which have affected that crust, both in originally dislocating and elevating portions of its strata, and in the actual phenomena of earthquakes (of many of which phenomena no other hypothesis appears to offer a sufficient explanation), while, at the same time, it would afford an adequate reason for the figure of the globe as a spheroid of rotation. 9. On this supposition, we should at once perceive a reason why the effects of the volcanic force may have been much more violent in earlier periods, while that mass of deposites which now covers the supposed volcanic nu- cleus was but gradually forming over it than at present ; and we shall also find a reason for the higher temperature, which many of the remains of both the animal and vegetable king- doms, found in the strata of countries now too cold for the existence of their recent analogies, appear to indicate as having formerly pre- vailed. 10. It must be remerabsred, that one of the essential conditions of the theory above sketched is, the operation of volcanic agency beneath the pressure of an incumbent ocean ; and that it does not, therefore, in any degree question the Neptunian origin of the majority of the rocks which have evidently been formed in the bosom of the ocean. With regard to the trap rocks alone, and perhaps the granitic, does it venture even to insinuate an opposite mode of formation. Mr. Conybeare next shows, that the Wer- nerian generalization of the phenomena is too hasty. It supposes the basset edges of the strata to occupy levels successively lower and lower in proportion as they are of less ancient formation, and as they recede from the pri- mitive chains, forming the edges of the basins in which they have been deposited. For if we compare the basset edges of the same strata on the opposite sides of the great European basin (assuming the primitive ranges of our own island as one of its borders, and those of the Alpine chains as the other), we shall find their level totally different. The oolite, for instance, whose highest point with us is less than 1 200 feet, attains a height of more than 4000 in the Jura chain, and in the mountains of the Tyrol has been observed by Mr. Buckland crowning some of the loftiest and most rugged summits of the Alps them- selves. Again, if we compare the inclination of the strata at the edges of the basin, we shall find every thing but the supposed regular gra- dation, from a highly elevated to a horizontal position ; on the contrary, we shall see the horizontal beds generally reposing at once upon the truncated edges of those which lie at very considerable angles ; and in place of the ge- neral conformity or parallelism which ought to prevail between the several formations, we shall observe, in many instances, appearances of the greatest irregularity in this respect ; and these irregularities will be found to in- crease in approaching those chains which are the most elevated. But if we suppose, that during the regular and gradual subsidence of the level of the ocean, in the Wernerian system, the continents were elevated by mechanical forces acting in a series of great convulsions, we shall perhaps obtain a nearer approximation to agreement with the actual phenomena, as deduced from observation. If these convulsions resulted from volcanic agency, we have already seen that there is every reason to believe this cause to have acted with most violence in the earliest periods; and this will sufficiently account for the greater derangement of the earlier rocks. That the valleys have been, in many in- stances, entirely excavated by the agency of powerful aqueous currents, and in all, greatly modified by the same cause, seems as com- pletely proved as the nature of the case can possibly admit. The same diluvial agency that has excavated the valleys, appears also to have swept off the superior strata from ex- tensive tracts which they once covered. The proofs of this are to be found in insulated hills, or outliers of those strata, placed at con- siderable distances from their continuous range, with which they have every appearance of having been once connected; in the abrupt and truncated escarpments which form the usual termination of the strata, and in the very great quantity of their debris, scattered frequently over tracts far distant from those where they still exist in situ. This stripping off the superstrata is appropriately termed denudation. The most important agency of this kind appears to have been exerted at an early pe- riod, and subsequently to the consolidation of all the strata, by an inundation which must have swept over them universally, and covered the whole surface with their debris indiscrimi- nately thrown together, forming the last great geological change to which the surface of our planet appears to have been exposed. To this general covering of water-worn debris derived from all the strata, the name of diluvium has been given, from the consi- deration of that great and universal cata- strophe to which it seems most properly as- signable. By this name it is intended to distinguish it from the partial debris occa- sioned by causes stiD in operation; such as the slight wear produced by the present rivers, the more violent action of torrents, &c. To the latter the name of alluvium has lately GEO 501 GEO been appropriated. It does not seem possible to assign any single and uniform direction to the currents which have driven the diluvial debris before them ; but they appear in every instance to have flowed (which indeed must of necessity be the case with the currents of sub- siding waters) as they were determined by the configuration of the adjoining country ; from the mountains, that is, towards the lower hills and plains. As far as England is concerned, this principle will produce a general tendency to a direction from north-west towards south and east, greatly modified, however, by obvious local circumstances. Another circumstance connected with the distribution of these travelled fragments is, that we often find them in masses of consi- derable size, accumulated in situations now separated by the intervention of deep valleys from the parent hills (if we may so speak), whence we know them to have been torn. This appears to be a demonstrative proof that these intervening valleys must have been ex- cavated subsequently to the transportation of these blocks ; for though we can readily con- ceive how the agency of violent currents may have driven these blocks down an inclined plane, or if the vis a tcrgo were sufficient, along a level surface, or even up a very slight and gradual acclivity, it is impossible to ascribe to them the Sisyphean labour of rolling rocky masses, sometimes of many tons in weight, up the face of abrupt and high escarpments. The attention of geologists was first directed to this phenomenon by the discoveries of Saussure, who noticed one of its most striking cases the occurrence of massive fragments torn from the primitive chains of the Alps, scattered at high levels on the escarpment of the opposite cal- careous and secondary chains of the Jura, although between the two points the deep valley containing the lake of Geneva is inter- posed. This phenomenon is one of very common occurrence. The Downs surrounding Bath (Hampton Down for example), though abruptly scarped, and surrounded by valleys more than 600 feet deep, have yet on their very summits flints transported from the dis- tant chalk hills. The simplest explanation of the fact will be, that these fragments were transported by the first action of the currents, before they had effected the excavation of the valk-ys, now cutting off all communication with the native rocks whence they were derived. The organic remains of land animals dis- persed through this diluvial gravel must, with the greatest probability, be referred to the races extinguished by the great convulsion which formed that gravel ; many of them are of species still inhabiting the countries where they arc thus found ; some of the species now inhabiting only other climates ; and some few, of species and genera now entirely unknown. To the same period, we may ascribe the bones of the same specks with the above, found in many caverns ; but, in many of these in- stances, it is probable that some of the animals now found there, previously inhabited them as their dens. Professor Buckland appears to have proved satisfactorily, that this must have been the case in the remarkable instance of the cavern lately discovered near Kirby Moor- side, Yorkshire. Here the remains found in the greatest abundance are those of hyaenas ; with these are mingled fragments of various animals, from the mammoth to the water-rat. All the bones present evident traces of having been mangled and gnawed ; and the whole are buried in a sediment of mud subsequently in- crusted over by staiactitical depositions. Pro- fessor BucklancTs explanation is, that this cavern was occupied by the hyaenas; who, according to the known habits of these animals, partially devoured even the bones of their prey, and dragged them for that purpose to their dens ; around their retreats, a similar congeries of mangled bones has been noticed by recent travellers. The proofs of these points, de- duced from the circumstances of the cavern, the state of the bones, and the ascertained habits of the animals in question, appear to be decisive. The sediment in which the bones are imbedded, and the occunvnce of the re- mains of the mammoths, and other species, only known (in these climates at least) in a fossil state, in the diluvial gravel, clearly refer their remains to the same era. Caverns containing bones of a similar class, the mammoth, the fossil species of rhinoceros, &c. have been found near Swansea, at Hatton-hill, (on the Mendip chain in Somersetshire), and near Plymouth. Rtv. W. D. Conybeare, Intro- duction. The ancient history of the globe, which may be regarded as the tiltimate object of geological researches, is undoubtedly one of the most curious subjects that can engage the attention of enlightened men. The lowest and most level parts of the earth, when penetrated to a very great depth, exhibit nothing but hori- zontal strata, composed of various substances, and containing almost all of them innumerable marine productions. Similar strata, with the sacie kind of productions, compose the hills even to a great height. Sometimes the shells are so numerous as to constitute the entire body of the stratum. They are almost every- where in such a perfect state of preservation, that even the smallest of them retain their most delicate parts, their sharpest ridges, and tenderest processes. They are found in eleva- tions far above the level of every part of the ocean, and in places to which the sea could not be conveyed by any presently existing cause. They are not merely enclosed in loose sand, but are often incrusted and penetrated on all sides by the hardest stones. Every part of the earth, every hemisphere, every continent, every island of any size, exhibits the same phe- GEO 502 GIL nomenon. We are therefore forcibly led to believe, not only that the sea has at one period or another covered all our plains, but that it must have remained there for a long time, and in a state of tranquillity ; which circumstance was necessary for the formation of deposites so extensive, so thick, in part so solid, and con- taining cxnvicc so perfectly preserved. A nice and scrupulous comparison of the forms, con- texture, and composition of these shells, and of those which still inhabit the sea, cannot detect the slightest difference between them. They have therefore once lived in the sea, and been deposited by it ; the sea consequently must have rested in the places where the de- position has taken place. Hence it is evident, that the basin or reservoir containing the sea has undergone some change, either in extent, situation, or both. The traces of revolutions become still more apparent and decisive when we ascend- a little higher, and approach nearer to the foot of the great chain of mountains. There are still found many beds of shells ; some of these are even larger and more solid ; the shells are quite as numerous, and as entirely preserved ; but they are not of the same species with those which were found in the less elevated regions. The strata which contain them are not so generally horizontal ; they have various degrees of inclination, and are sometimes situated ver- tically. While in the plains and low hills it was necessary to dig deep in order to detect the succession of the strata, here we perceive them by means of the valleys, which time or violence has produced, and which disclose their edges to the eye of the observer. Thus the sea, previous to the formation of the horizontal strata, had formed others, which by some means have been broken, lifted up, and overturned in a thousand ways. But the sea has not always deposited stony substances of the same kind. It has observed a regular succession as to the nature of its deposites ; the more ancient the strata are, so much the more uniform and extensive are they ; and the more recent they are, the more limited are they, and the more variation is observed in them at small distances. Thus the great catastrophes which have produced revolutions in the basins of the sea, were preceded, accom- panied, and followed by changes in the nature of the fluid, and of the substances which it held in solution ; and when the surface of the seas came to be divided by islands and pro- jecting ridges, different changes took place in every separate basin. These irruptions and retreats of the sea have neither been slow nor gradual ; most of the catastrophes which have occasioned them have been sudden ; and this is easily proved, espe- cially with regard to the last of them, or the Mosaic deluge, the traces of which are very conspicuous. In the northern regions it has left the carcasses of some large quadrupeds, which the ice had arrested, and which are pre- served even to the present day, with their skin, their hair, and their flesh. If they had not been frozen as soon as killed, they must have been quickly decomposed by putrefaction. But this perpetual frost could not have taken pos- session of the regions which these animals in- habited, except by the same cause which destroyed them: this cause must therefore have been as sudden as its effect. The two most remarkable phenomena of this kind, and which must for ever banish all idea of a slow and gradual revolution, are the rhinoceros, discovered in 1771 on the banks of the Vilttoui, and the elephant, recently found by Mr. Adams near the mouth of the Sena. This last retained its flesh and skin, on which was hair of two kinds ; one short, fine, and crisped, resembling wool, and the other like bristles. The flesh was still in such high preservation, that it was eaten by dogs. Every part of the globe bears the impress of these great and terrible events so distinctly, that they must be visible to all who are qualified to read their history in the remains which they have left behind. See Cuvier's Theory of the Earth. I shall conclude this article by stating, that this naturalist, the most learned of the present day, as well as Dolomieu, Deluc, and Greenough, concur in thinking, that not above 5000 or 6000 years have elapsed since the period of the deluge, which agrees with the Mosaic epoch of that catastrophe. GERMINATION. The vital develop- ment of a seed, when it first begins to grow. GIBBSITE. This mineral commonly occurs in irregular stalactites from one to three inches in length, and not less than an inch in diameter. Sometimes in large tuberous masses. Structure indistinctly fibrous. Somewhat harder than calcareous spar. Slightly trans- lucent. Of a dirty white colour. Sp. grav. 2.40. It contains alumina 64.8, water 34.7. Infusible before the blowpipe. It is found at Richmond in Massachusets, N. America, in a neglected mine of brown haematite ore. Phillips'' Mineralogy. G1ESECKITE. The name given by Stromeyer to a mineral discovered by M. Giesecke, of a grey and brown colour, white streak, and specific gravity 2-7 to 2.9. It belongs to the rhomboidal system of Mohs. Its form is designated R Q0 R -f QQ. No cleavage. GILDING. The art of covering the sur- faces of bodies with gold. The gold prepared for painting is called shell-gold or gold-powder, and may be obtained by amalgamating one part of gold with eight of quicksilver, and afterward evaporating the latter, which leaves the gold in the form of powder ; or otherwise the metal may be reduced to powder by mechanical trituration. For this purpose, gold leaf must be ground with honey or strong gum-water for a long time ; GIL 503 GIL and when the powder is sufficiently fine, the honey or gum may be washed off with water. For gold gilding by friction, a fine linen rag is steeped in a saturated solution of gold till it has entirely imbibed the liquor; this rag is then dried over a fire, and afterward burned to tinder. Now, when any thing is to be gilded, it must be previously well burnished ; a piece of cork is then to be dipped, first into a solution of salt in water, and afterward into the black powder ; and the piece, after it is burnished, rubbed with it For water gilding, the solution of gold may be evaporated till it is of an oily consistence, suffered to crystallize, and the crystals dis- solved in water be employed instead of the acid solution. If this be copiously diluted with alcohol, a piece of clean iron will be gilded by being steeped therein. Or add to the solution about three times its quantity of sulphuric ether, which will soon take up the nitre-muriate of gold, leaving the acid colour- less at the bottom of the vessel, which must then be drawn off. Steel dipped into the ethereal solution for a moment, and instantly washed in clean water, will be completely and beautifully covered with gold. The surface of the steel must be well polished, and wiped very clean. For the method called Grecian gilding, equal parts of sal ammoniac and corrosive sublimate are dissolved in nitric acid, and a solution of gold is made in this menstruum : upon this the solution is somewhat concen- trated, and applied to the surface of silver, which becomes quite black ; but, on being ex- posed to a red heat, it assumes the appearance of gilding. The method of gilding silver, brass, or copper, by an amalgam, is as follows : Eight parts of mercury, and one of gold, are incor- porated together by heating them in a crucible. As soon as the gold is perfectly dissolved, die mixture is poured into cold water, and is then ready for use. Before the amalgam can be laid upon the surface of the metal, this last is brushed over with dilute aquafortis, in which it is of ad- vantage that some mercury may have been dissolved. Some artists then wash the metal in fair water, and scour it a little with fine sand, previous to the application of the gold ; but others apply it to the metal while still wet witli the aquafortis. But in either case the amalgam must be laid on as uniformly as possible, and spread very evenly with a brass- wire brush, wetted from time to time with fair water. The piece is then laid upon a grate over a charcoal fire, or in a small oven or furnace adapted to this purpose. The heat drives off the mercury, and leaves the gold behind. Its defects are then seen, and may be remedied by successive applications of more amalgam, and additional application of heat. The expert artists, however, make these ad- ditional applications while the piece remains in the furnace, though the practice is said to be highly noxious on account of the mercurial fumes. After this it is rubbed with gilders' wax, which may consist of four ounces of bees* wax, one ounce of verdigris, and one ounce of sulphate of copper; then expose it to a red heat, which burns off the wax ; and, lastly, the work is cleared with the scratch brush, and burnished, if necessary, with a steel tool. The use of the wax seems to consist merely in covering defects, by the diffusion of a quantity of red oxide of copper, which is left behind after the burning. The gilding of iron by mere heat is per- formed by cleaning and polishing its surface, and then heating it till it has acquired a blue colour. When this has been done, the first layer of gold leaf is put on, slightly burnished down, and exposed to a gentle fire. It is usual to give three such layers, or four at the most, each consisting of a single leaf for com- mon works, or two for extraordinary ones. The heating is repeated at each layer, and last of all the work is burnished. The gilding of buttons is done in the fol- lowing way : When the buttons, which are of copper, are made, they are dipped into dilute nitric acid to clean them, and then burnished with a hard black stone. They are then put into a nitric solution of mercury, and stirred about with a brush till they are quite white. An amalgam of gold and mercury is then put into an earthen vessel with a small quantity of dilute nitric acid, and in this mixture the buttons are stirred, till the gold attaches to their surface. They are then heated over the fire, till the mercury begins to run, when they are thrown into a large cap made of coarse wool and goat's hair, and in this they are stirred about with a brush. The mercury is then volatilized by heating over the fire in a pan, to the loss of the article, and injury of the workmen's health ; though the greater part might be recovered, with less injury to the operators. By Act of Parliament, a gross of buttons, of an inch diameter, are required to have five grains of gold on them ; but many are deficient even of this small quantity. Painting with gold upon porcelain or glass is done with the powder of gold, which remains behind after distilling the aqua regia from a solution of that metal. It is laid on with bo- rax and gum water, burned in, and polished. The gilding of glass is commonly effected by covering the part with a solution of borax, and applying gold leaf upon it, which is after- ward fixed by burning. Gilding in oil is performed by means of a paint sold under the name of gold size. It consists of drying oil, (that is to say, linseed oil boiled upon litharge), and mixed with yel- low ochre. It is said to improve in its quality by keeping. This is laid upon the work ; and when it has become so dry as to adhere to the GLA 504 GLA fingers without soiling them, the gold leaf is laid on, and pressed down with cotton. This method of gilding is proper for work intended to be exposed to the weather. The method of gilding in burnished gold consists in covering the work with parchment size and whiting,, thinly laid on at five or six different times. This is covered with a yellow size made of Armenian bole, a little wax, and some parchment size ; but in this, as in most other compositions used in the arts, there are variations which depend on the skill or the ca- price of the artists. When the size is dry, the gold is applied upon the surface previously wetted with clear water. A certain number of hours after this application, but previous to the perfect hardening of the composition, the gold may be very highly burnished with a tool of agate made for this purpose. This gilding is fit only for work within doors ; for it readily comes off upon being wetted. The edges of the leaves of books are gilded by applying a composition of one part Arme- nian bole, and one quarter of a part of sugar- candy, ground together with white of eggs. This is burnished while the book remains in the press, and the gold is laid on by means of a little water. Leather is gilded either with leaf-brass or silver, but most commonly by the latter, in which case a gold-coloured varnish is laid over the metal. Tin-foil may be used instead of silver- leaf for this less perfect gilding upon such works as do not possess flexibility. GISMONDINE. Abrazite. GLACIES MARLE. Mica. GLANCE. The name annexed to certain minerals which have a metallic or pseudo- metallic lustre. Thus we see glance-coal, lead- glance, antimony-glance, &c. GLASS. Most of the treatises which I have seen on the manufacture of glass, illustrate a well known position, that it is easy to write a large volume, which shall communicate no de- finite information. There are five distinct kinds of glass at present manufactured : 1. Flint glass, or glass of lead. 2. Plate glass, or glass of pure soda. 3. Crown glass, the best window-glass. 4. Broad glass, a coarse window-glass. 5. Bottle, or coarse green glass. 1. Flint Glass, so named because the silice- ous ingredient was originally employed in the form of ground flints. It is now made of the following composition : Purified Lynn sand, 1 00 parts Litharge or red lead, 60 Purified pearl ash, 30 To correct the green colour derived from combustible matter, or oxide of iron, a little black oxide of.manganese is added, and some- times nitre and arsenic. The fusion is accom- plished usually in about thirty hours. 2. Plate Glass. Good carbonate of soda procured by decomposing common salt with pearl ash, is employed as the flux. The propor- tion of the materials is, Pure sand, 43-0 Dry subcarbonate of soda, 26-5 Pure quicklime, 4- Nitre 1-5 Broken plate glass, 25-0 100-0 About seventy parts of good plate glass may be run off from these materials. 3. Crotvn, or fine window-glass. This is made of sand vitrified by the impure barilla, manufactured by incineration of sea weed on the Scotch and Irish shores. The most ap- proved composition is, By measure. By weight. Fine sand purified, 5 200 Best kelp ground, 11 330 These ingredients are mixed, and then thrown into the fritting arch, where the sul- phur of the kelp is dissipated, and the matters are thoroughly incorporated, forming, when withdrawn at the end of four hours, a greyish- white tough mass, which is cut into brick- shaped pieces, and after concretion and cooling, piled up for use. By long keeping a soda efflorescence forms on their surface. They are then supposed to have become more valuable. These bricks are put into the melting-pots, and sometimes a proportion of common salt is thrown in towards the end of the operation, if the vitrification has been imperfect. Under the article Sulphate of Soda, in this Diction- ary, retained from the old edition, there is the following sentence. " Pajot des Charmes has made some experiments on it in fabricating glass ; with sand alone it v/ould not succeed, but equal parts of carbonate of lime, sand, and dried sulphate of soda, produced a clear, solid, pale yellow glass." In the Annals of Philo- sophy for Jan. 1817, we find the following notice from Schweigger's Journal, xv. 89. : Gehlen, some time before his death, was occu- pied with experiments on the preparation of glass, by means of sulphate of soda. Profes- sor Schweigger has lately published the result of his trials. He found that the following proportions were the best: Sand, . . . 100 Dry sulphate of soda, . 50 Dry quicklime in powder, . 17 to 20 Charcoal, ... 4 This mixture always gives a very good glass without any addition whatever. During the fusion, the sulphuric acid is decomposed and driven off, and the soda unites with the silica. The sulphate of soda vitrifies very imperfectly, when mixed alone with the silica. The vitri- fication succeeds better when quicklime is added ; and it succeeds completely, when the proportion of charcoal in the formula is added ; because the sulphuric acid is thereby decom- posed and dissipated. This decomposition may be eitner effected during the making of the GLA 505 GLA glass, or before, at the pleasure of the work- men. 4. Broad Glass. This is made of a mix- ture of soap-boilers' waste, kelp, and sand. The first ingredient consists of litne used for rendering the alkali of the soap-boiler caustic, the insoluble matter of his kelp or barilla, and a quantity of salt and water, all in a pasty state. The proportions necessarily vary. 2 of the waste, 1 of kelp, and 1 of sand, form a pretty good bread glass. They are mined together, dried, and (ritted. 5. Bottle Glass is the coarsest kind. It is made of soaper's waste aad river sand, in pro- portions which practice must determine accord- ing to the quantity of the waste ; some soap- boilers extracting more saline matter, and other less from their kelps. Common sand and lime, with a little common clay and sea salt, form a cheap mixture for bottle glass. As far as observation has hitherto directed us, it appears to be a general rule, that the hardness, brittleness, elasticity, and other me- chanical properties of congealed bodies, are greatly affected by the degree of rapidity with which they assume the solid state. This, which no doubt is referable to the properly of crystal- lization, and its various mode?, is remarkably seen in steel and other metals, and seems to obtain in glass. When a drop of glass is suf- fered to fall into water, it is found to possess the remarkable property of flying into minute pieces, the instant a small part of the tail is broken off. This, which is commonly distin- guished by the name of Prince Rupert's drop, is similar to the philosophical phial, which is a small vessel of thick glass suddenly cooled by exposure to the air. Such a vessel possesses the property of flying in pieces when the small- est piece of flint or angular pebble is let fall into it, though a leaden bullet may be dropped into it from some height without injury. Many explanations have been offered, to ac- count for these and other similar appearances, by referring to a supposed mechanism or arrangement of the particles, or sudden con- finement of the matter of heat. The immediate cause, however, appears to be derived from the fact, that the dimensions of bodies suddenly cooled remain larger than if the refrigeration had been more gradual. Thus the specific gravity of steel hardened by sudden cooling in water is less, and its di- mensions consequently greater than that of the same steel gradually cooled. It is more than probable, that an effect of the same nature obtains in glass ; so that the dimen- sions of the external and suddenly cooled sur- face remain larger than are suited to the ac- curate envelopment of the interior part, which is less slowly cooled. In most of the metals, the degree of flexibility they possess, must be sufficient to remedy this inaccuracy as it takes place ; but in glass, which, though very elastic and flexible, is likewise excessively brittle, the adaptation of the parts, urged different ways by their disposition to retain their respective dimensions, and likewise to remain in contact by virtue of the cohesive attraction, can be maintained only by an elastic yielding of the whole, as far as may be, which will therefore remain in a state of tension. It is not there- fore to be wondered at that a solution of con- tinuity of any part of the surface should destroy this equilibrium of elasticity; and that the sudden action of all the parts at once of so brittle a material should destroy the continuity of the whole, instead of producing an equili- brium of any other kind. - Though the facts relating to this disposi- tion of glass too suddenly cooled are numerous and interesting to the philosopher, yet they constitute a serious evil with respect to the uses of this excellent material. The remedy of the glass-maker consists in annealing the several articles, which is done by placing them in a furnace near the furnace of fusion. The glasses are first put into the hottest part of this furnace, and gradually removed to the cooler parts at regular intervals of time. By this means the glass cools very slowly through- out, and is hi a great measure free from the defects of glass which has been too hastily cooled. M. Reaumur was the first who made any direct experiments upon the conversion of glass into porcelain. Instances of this effect may be observed among the rubbish of brick- kilns, where pieces of green bottles are not unfrequently subjected by accident to the re- quisite heat ; but the direct process is as fol- lows : A vessel of green glass is to be filled up to the top with a mixture of white sand and gypsum, and then set in a large crucible upon a quantity of the same mixture, with which the glass vessels must also be surrounded and covered over, and the whole pressed down rather hard. The crucible is then to be covered with a lid, the junctures well luted, and put into a potter's kiln, where it must remain during the whole time that the pottery is baking, after which the glass vessel will be found transformed into a milk-white porcelain. The glass, on fracture, appears fibrous, as if it were composed merely of silken threads laid by the side of each other : it has also quite lost the smooth and shining appearance of glass, is very hard, and emits sparks of fire when struck with steel, though not so briskly as real porcelain. Lewis observed that the above-mentioned materials have not exclu- sively this effect upon glass ; but that pow- dered charcoal, soot, tobacco-pipe clay, and bone-ashes, produce the same change. It is remarkable that the surrounding sand becomes in some measure agglutinated by this process, which, if continued for a sufficient length of time, entirely destroys the texture of the glass, and renders it pulverulent. The ancient stained glass has been much GLA 506 GLU admired, and beautiful paintings on this sub- stance have been produced of late years. The colouts are of the nature of those used in enamelling, and the glass should have no lead in its composition. M. Brogniart has made many experiments on this subject. The pur- ple of Cassius, mixed with six parts of a flux composed of borax and glass made with silex and lead, produces a very beautiful violet, but liable to turn blue. Red oxide of iron, pre- pared by means of the nitric acid and subse- quent exposure to fire, and mixed with a flux of borax, sand, and a small portion of minium, produces a fine red. Muriate of silver, oxide of zinc, white clay, and the yellow oxide of iron, mixed together without any flux, pro- duce a yellow, light or deep, according to the quantity laid on, and equal in beauty to that of the ancients. A powder remains on the surface after baking, which may easily be cleaned off. Blue is produced by oxide of cobalt, with a flux of sUex, potash, and lead. To produce a green, blue must be put on one side of the glass, and yellow on the other ; or a blue may be mixed with yellow oxide of iron. Black is made by a mixture of blue with the oxides of manganese and iron. The bending of the glass, and alteration of the colours in baking, are particularly to be avoided, and require much care. Gypsum has been recommended for their support, but this frequently renders the glass white, and cracked in all directions, probably from the action of the hot sulphuric acid on the alkali in the glass. M. Brogniart placed his plates of glass, some of them much larger than any ever before painted, on very smooth plates of earth or porcelain unglazed, which he found to answer extremely well. GLAUBER SALT. Native sulphate of soda. Its colours are greyish and yellowish- white. It occurs in mealy efflorescences, prismatic crystals, and imitative shapes. Lustre vitreous. Cleavage threefold. Fracture conchoidal. Soft. Brittle. Sp. gr. 2-2 to 2-3. Taste at first cooling, then saline and bitter. Its solution does not, like that of Epsom salt, afford a precipitate with an alkali. Its consti- tuents are, sulphate of soda 67 ; carbonate of soda 16i; muriate of soda 11; carbonate of lime 5-64. It occurs along with rock salt and Epsom salt, on the borders of salt lakes, and dissolved in the waters of lakes and the ocean ; in efflorescences on moorish ground ; also on sandstone, marl-slate, and walls. It is found at Eger in Bohemia, on meadow-ground, as an efflorescence, and in galleries of mines in seve- ral places. Jameson. GLAUBERITE. Colours greyish-white, and wine-yellow. Crystallized in very low oblique four-sided prisms, the lateral edges of which are 104 28', and 75 32'. Lateral planes tranversely streaked : terminal planes smooth. Shining. Fracture foliated or conchoi- dal. Softer than calcareous spar. Transparent. Brittle. Sp. gr. 2-7. It decrepitates before the blowpipe, and melts into white enamel. In water it becomes opaque, and is partly soluble. Its constituents are, dry sulphate of lime 49 ; dry sulphate of soda 51. It is found imbed- ded in rock salt, at Villaruba, near Ocana, in New Castile in Spain. Jameson. GLAZING. See POTTERY. GLIM MER. A name occasionally applied to micaceous earths. GLIADINE. See GLUTEN. GLUCINA. This earth was discovered by Vauquelin, first in the aqua marina, and after- ward in the emerald, in the winter of 1798. Its name is derived from its distinguishing character of forming with acids salts that are sweet to the taste. The following is his me- thod of obtaining it : Let 1 00 parts of beryl or emerald be reduced to a fine powder, and fused in a silver crucible with 300 of pure potash. I^et the mass be diffused in water, and dissolved by adding muriatic acid. Evaporate the solution, taking care to stir it toward the end : mix the residu- um with a large quantity of water, and filter, to separate the silex. Precipitate the filtered liquor which contains the muriates of alumina and glucina, with carbonate of potash ; wash the precipitate, and dissolve it in sulphuric acid. Add a certain quantity of sulphate of potash, evaporate, and crystals of alum will be obtained. When no more alum is afforded by adding sulphate of potash and evaporating, add solution of carbonate of ammonia in excess, shake the mixture well, and let it stand some hours, till the glucina is redissolved by the ex- cess of carbonate of ammonia, and nothing but the alumina remains at the bottom of the vessel. Filter the solution, evaporate to dryness and expel the acid from the carbonate of glu- eina, by slight ignition in a crucible. Thus 15 or 16 per cent, of pure glucina will be obtained. Glucina thus obtained is a white, soft powder, light, insipid, and adhering to the tongue. It does not change vegetable blues. It does not harden, shrink, or agglutinate by heat; and is infusible. It is insoluble in water, but forms with it a slightly ductile paste. It is dissolved by potash, soda, and carbonate of ammonia ; but not by pure am- monia. It unites with sulphuretted hydrogen. Its salts have a saccharine taste, with some- what of astringency. See SALT. Sir II. Davy's researches have rendered it more than probable, that glucina is a compound of oxygen, and a peculiar metallic substance, which may be called glucinum. By heating it along with potassium, the latter was con- verted for the most part into potash ; and dark coloured particles, havingametallicappearance, were found diffused through the mass, which regained the earthy character by being heated in the air, and by the action of water. In this last case, hydrogen was slowly disengaged. GLU 507 GLU According to Sir H. Davy, the prime equiva- lent of glucina would be 3.6 on the oxygen scale, and that of glucinum 2.6. These are very nearly the equivalents of lime and cal- cium. From the composition of the sulphate, Berzelius infers the equivalent to be 3.2, and that of its basis 2.2. GLUE. An inspissated jelly made from the parings of hides and other effals, by boil- ing them in water, straining through a wicker basket, suffering the impurities to subside, and then boiling it a second time. The articles should first be digested in lime water, to cleanse them from grease and dirt; then steeped in water, stirring them well from time to time ; and lastly, laid in a heap, to have the water pressed out, before they are put into the boiler. Some recommend, that the water should be kept as nearly as possible to a boiling heat, without suffering it to enter into ebullition. In this state it is poured into flat frames or moulds, then cut into square pieces when congealed, and afterward dried in a coarse net. It is said to improve by age ; and that glue is reckoned the best, which swells considerably without dissolving by three or four days' infusion in cold water, and recovers its former dimensions and properties by drying. Shreds or parings of vellum, parchment, or white leather, make a clear and almost colour- less glue. GLUTEN (VEGETABLE) . If wheat- flour be made into a paste, and washed in a large quantity of water, it is separated into three distinct substances : a mucilaginous saccharine matter, which is readily dissolved in the liquor, and may be separated from it by evaporation ; starch, which is suspended in the fluid, and subsides to the bottom by repose ; and gluten, which remains in the hand, and is tenacious, very ductile, somewhat elastic, and of a brown-grey colour. The first of these substances does not essentially differ from other saccharine mucilages. The second, namely, the starch, forms a gluey fluid by boiling in water, though it is scarcely, if at all, acted upon by that fluid when cold. Its habitudes and products with the fire, or with nitric acid, are nearly the same as those of gum and of sugar. It appears to be as much more remote from the saline state than gum, as gum is more remote from that state than sugar. The vegetable gluten, though it existed before the washing in the pulverulent form, and has acquired its tenacity and adhesive qualities from the wate; it has imbibed, is nevertheless totally insoluble in this fluid. It has scarcely any taste. When dry, it is semitransparent, and resembles glue in its colour and appearance. If it be drawn out thin, when first obtained, it may be dried by exposure to the air ; but if it be exposed to warmth and moisture while wet, it putrefies like an animal substance. The dried gluten applied to the flame of a candle, crackles, swells, and burns, exactly like a feather, or piece of horn. It affords the same products by destructive distillation as animal matters do ; is not soluble in alcohol, oils, or ether ; and is acted upon by acids and alkalis, when heated. According to Rouelle, it is the same with the caseous substance of milk. Gluten of Wheat M. Taddey, an Italian chemist, has lately ascertained that the gluten of wheat may be decomposed into two princi- ples, which he has distinguished by the names, gliadine (from yX/, gluten), and zimome {from ?Vrj, ferment). They are obtained in a separate state by kneading the fresh gluten in successive portions of alcohol, as long as that liquid continues to become milky, when diluted with water. The alcohol solutions being set aside, gradually deposit a whitish matter, consisting of small filaments of gluten, and become perfectly transparent. Being now left to slow evaporation, the gliadine remains behind, of the consistence of honey, and mixed with a little yellow resinous matter, from which it may be freed by digestion in sulphuric ether, in which gliadine is not sensibly soluble. The portion of the gluten not dissolved by the alcohol is the zimome. Properties of Gliadine. When dry, it has a straw-yellow colour, slightly transparent, and in thin plates, brittle, having a slight smell, similar to that of honeycomb, and, when slightly heated, giving out an odour similar to that of boiled apples. In the mouth, it becomes adhesive, and has a sweetish and balsamic taste. It is pretty soluble in boiling alcohol, which loses its transparency in proportion as it cools, and then retains only a small quantity in solution. It forms a kind of varnish on those bodies to which it is applied. It softens, but does not dissolve in cold distilled water. At a boiling heat it is converted into froth, and the liquid remains slightly milky. It is specifically heavier than water. The alcoholic solution of gliadine becomes milky when mixed with water, and is preci- pitated in white flocks by the alkaline carbo- nates. It is scarcely affected by the mineral and vegetable acids. Dry gliadine dissolves in caustic alkalis and in acids. It swells upon red-hot coals, and then contracts in the manner of animal substances. It burns with a pretty lively flame, and leaves behind it a light spongy charcoal, difficult to incinerate. Glia- dine, in some respects, approaches the pro- perties of resins ; but differs from them in being insoluble in sulphuric ether. It is very sensibly affected by the infusion of nut-galls. It is capable of itself of undergoing a slow fermentation, and produces fermentation in saccharine substances. From the flour of barley, rye, or oats, no GOL 508 GOL gluten can be extracted, as from that of wheat, probably because they contain too small a quantity. See ZIMOME. GNEISS. A compound rock, consisting of felspar, quartz, and mica, disposed in slates, from the predominance of the mica scales. Its structure is called by Werner, granular-slaty. This geognostic formation is always stratified ; contains sometimes crystals of schorl, tour, maline, and garnet, and is peculiarly rich in metallic ores. GOLD is a yellow metal, of specific gravity 19.3. It is soft, very tough, ductile, and malleable ; unalterable and fixed, whether exposed to the atmosphere, or to the strongest heat of furnaces. Powerful burning mirrors have volatilized it ; and it has been driven up in fumes, in the metallic state, by flame urged upon it by a stream of oxygen gas. The elec- tric shock converts it into a purple oxide, as may be seen by transmitting that commotion through gold leaf, between two plates of glass ; or by causing the explosive spark of three or more square feet of coated glass, to fall upon a gilded surface. A heat of 32 W. or perhaps 1300 F. is required to melt it, which does not happen till after ignition. Ife colour when melted, is of a bluish-green ; and the same colour is exhibited by light transmitted through gold leaf. The limits of the ductility and malleability of gold are not known. The method of extending gold used by the gold-beaters consists in hammering a number of thin rolled plates between skins or animal membranes. By the weight and measure of the best wrought gold leaf, it is found, that one grain is made to cover 56f square inches ; and from the specific gravity of the metal, to- gether with this admeasurement, it follows, that the leaf itself is -^-^J-^Q part of an inch thick. This, however, is not the limit of the malleability of gold ; for the gold- beaters find it necessary to add three grains of copper in the ounce to harden the gold, which otherwise would pass round the irregularities of the newest skins, and not over them ; and in using the old skins, which are not so perfect and smooth, they proceed so far as to add twelve grains. The wire which is used by the lace- makers is drawn from an ingot of silver, pre- viously gilded. \In this way, from the known diameter of the wire, or breadth when flattened, and its length, together with the quantity of gold used, it is found, by computation, that the covering of gold is only one 12th part of the thickness of gold-leaf, though it still is so perfect as to exhibit no cracks when viewed by a microscope. No acid acts readily upon gold but aqua regia, and aqueous chlorine. Chromic acid added to the muriatic enables it to dissolve gold. The small degree of concentration of which aqueous chlorine is susceptible, and the im- perfect action of the latter acids, render aqua regia the most convenient solvent for this metal. When gold is immersed in aqua regia, an effervescence takes place ; the solution tinges animal matters of a deep purple, and corrodes them. By careful evaporation, fine crystals of a topaz colour are obtained. The gold is precipitated from its solvent, by a great number of substances. Lime and magnesia precipitate it in the form of a yellowish powder. Alkalis exhibit the same appearance ; but an excess of alkali redissolves the precipitate. The precipitate of gold obtained from aqua regia by the addition of a fixed alkali appears to be a true oxide, and is soluble in the sulphuric, nitric, and muriatic acids ; from which, how- ever, it separates by standing, or by evapora- tion of the acids. Gallic acid precipitates- gold of a reddish colour, very soluble in the nitric acid, to which it communicates a fine blue colour. Ammonia precipitates the solution of gold much more readily than fixed alkalis. This precipitate, which is of a brown, yellow, or orange colour, possesses the property of de- tonating with a very considerable noise when gently heated. It is known by the name of fulminating gold. The presence of ammonia is necessary to give the fulminating property to the precipitate of gold ; and it will be pro- duced by precipitating it with fixed alkali, from an aqua regia previously made by adding sal ammoniac to nitric acid ; or by precipitating the gold from pure aqua regia, by means of sal ammonia, instead of the ammonia alone. The fulminating gold weighs one-fourth more than the gold made use of. A considerable degree of precaution is necessary in preparing this substance. It ought not to be dried but in the open air, at a distance from a fire, be- cause a very gentle heat may cause it to explode. Several fatal accidents have arisen from its explosion, in consequence of the friction of ground stoppers in bottles containing this substance, of which a small portion remained in the neck. Fulminating gold, when exposed by Ber- th ollet to a very gentle heat in a copper tube, with the pneumatical apparatus of mercury, was deprived of its fulminating quality, and converted into an oxide at the same time that ammoniacal gas was disengaged. From this dangerous experiment it is ascertained, that fulminating gold consists of oxide- of gold combined with ammonia. The same eminent philosopher caused fulminating gold to ex- plode in copper vessels. Nitrogen gas was disengaged, a few drops of water appeared, and the gold was reduced to the metallic form. In this experiment he infers, that the ammonia was decomposed ; that the nitrogen, suddenly assuming the elastic state, caused the explo- GOL 509 GOU sion, while the oxygen of the oxide united with the hydrogen of the alkali, and formed the water. This satisfactory theory was still farther confirmed by the decomposition of fulminat- ing gold, which takes place in consequence of the action of the concentrated sulphuric acid, of melted sulphur, fat oils, and ether; all which deprived it of its fulminating quality, by combining with its ammonia. Sulphurets precipitate gold from its solvent, the alkali uniting with the acid, and the gold falling down combined with the sulphur ; of which, however, it may be deprived by mo- derate heat. Most metallic substances precipitate gold from aqua regia : lead, iron, and silver, pre- cipitate it of a deep and dull purple colour ; copper and iron throw it down in its metallic state ; bismuth, zinc, and mercury, likewise precipitate it. A plate of tin, immersed in a solution of gold, affords a purple powder, called the purple powder of Cassius, which is used to paint in enamel. Ether, naphtha, and essential oils, take gold from its solvent, and from liquors, which have been called potable gold. The gold which is precipitated by evaporation of these fluids, or by the addition of sulphate of iron to the so- lution of gold, is of the utmost purity. Most metals unite with gold by fusion. With silver it forms a compound, which is paler in proportion to the quantity of silver added. It is remarkable, that a certain pro- portion, for example a fifth part, renders it greenish. From this circumstance, as well as from that of a considerable proportion of these metals separating from each other by fusion, in consequence of their different specific gravi- ties, when their proportions do not greatly differ, it should seem that their union is little more than a mere mixture without combina- tion ; for, as gold leaf transmits the green rays of light, it wUl easily follow, that particles of silver, enveloped in particles of gold, will re- flect a green instead of a white light. A strong heat is necessary to combine pla- tina with gold : it greatly alters the colour of the gold, if its weight exceed the forty-seventh part of the mass. Mercury is strongly disposed to unite with gold, in all proportions, with which it forms an amalgam: this, like other amalgams, is softer the larger the proportion of mercury. It softens and liquefies by heat, and crystal- lizes by cooling. Lead unites with gold, and considerably impairs its ductility, one-fourth of a grain to an ounce rendering it completely brittle. Copper renders gold less ductile, harder, more fusible, and of a deeper colour. This is the usual addition in coin, and other articles used in society. Tin renders it brittle in propor- tion to its quantity ; but it is a common error of chemical writers to say, that the slightest addition is sufficient for this purpose. When alloyed with tin, however, it will not bear a red heat. With iron it forms a grey mixture, which obeys the magnet. This metal is very hard, and is said to be much superior to steel for the fabrication of cutting instruments. Bismuth renders gold white and brittle ; as do likewise nickel, manganese, arsenic, and antimony. Zinc produces the same effect; and, when equal in weight to the gold, a metal of a fine grain is produced, which is said to be well adapted to form the mirrors of reflecting telescopes, on account of the fine polish it is susceptible of, and its not being subject to tarnish. The alloys of gold with molybdena are not known. It could not be mixed with tungsten, on account of the infusibility of this last substance. Mr. Hatchett gives the fol- lowing order of different metals, arranged as they diminish the ductility of gold : bismuth, lead, antimony, arsenic, zinc, cobalt, manga- nese, nickel, tin, iron, platina, copper, silver. The first three were nearly equal in effect; and the platina was not quite pure. For the purposes of coin, Mr. Hatchett considers an alloy of equal parts of silver and copper as to be preferred, and copper alone as preferable to silver alone. The peroxide of gold thrown down by pot- ash, from a solution of the neutral muriate, consists, according to Berzelius, of 100 gold and 12 oxygen. It is probably a tritoxide. The protoxide of a greenish colour, is pro- cured by treating with potash water muriate of gold, after heat has expelled the chlorine. It seems to consist of 100 metal -f- 4 oxygen. The prime equivalent of gold comes out ap- parently 25. The gold coins of Great Britain contain eleven parts of gold, and one of copper. See ASSAY, GILDING, and ORES of GOLD. GONG, or TAM-TAM, of the Chinese ; a species of cymbal which produces a very loud sound on being struck. It is an alloy, according to M. Thenard's analysis, of about 80 parts of copper and 20 of tin. GONIOMETER. An instrument for measuring the angles of crystals. See CRYS- TALLIZATION. GORGONIA NOBILIS. The red coral. It consists of an interior stem, composed of gelatinous matter and carbonate of lime, with a cortex, consisting of membrane with carbo- nate of lime, coloured by some unknown sub- stance. GOULARD'S EXTRACT. A satu- rated solution of subacetate of Iea4^- See LEAD. GOUTY CONCRETIONS. These have been called chalk-stones from their appear- ance; but Dr. Wollaston first demonstrated their true composition to be uric acid com- bined with ammonia, and thus explained the mysterious pathological relation between gout and gravel. See CALCULUS (URIXARY). GRA 510 GRE Gouty concretions are soft and friable. They are insoluble in cold, but slightly in boiling water. An acid being added to this solution, seizes the soda, and the uric acid is deposited in small crystals. These concre- tions dissolve readily in water of potash. An artificial compound may be made by tritu- rating uric acid and soda with warm water, which exactly resembles gouty concretions in its chemical constitution. GRAINER. The lixivium obtained by infusing pigeons' dung in water, is used for giving flexibility to skins in the process of tanning, and is called the grainer. GRAMMATITE. See TREMOLITE. GRANATITE. See GRENATITE. GRANITE. A compound rock, consist- ing of quartz, felspar, and mica, each crys- tallized and cohering by mutual affinity, with- out any basis or cement. The felspar com- monly predominates, and the mica is in small- est quantity. The colours of the felspar are white, red, grey, and green. The quartz is light grey, and the mica dark. The granular crystals vary exceedingly in size, in different granite rocks. Occasionally granite is stra- tified ; but sometimes no stratification can be perceived. Large globular masses, called rolling stones, are frequently met with, com- posed each of concentric lamellar concretions. Schorl, garnet, and tinstone, are frequently present in granite. Tin and iron are the only metals abundantly found in this rock. It contains molybdena, silver, copper, lead, bis- muth, arsenic, titanium, tungsten, and cobalt. It is, however, poorer in ores than many other rock formations. GRANULATION. The method of di- viding metallic substances into grains or small particles, in order to facilitate their combina- tion with other substances, and sometimes for the purpose of readily subdividing them by weight. This is done either by pouring the melted metal into water, or by agitating it in a box until the moment of congelation, at which in- stant it becomes converted into a powder. Various contrivances are used to prevent danger, and ensure success, in the several manufactories that require granulation. Cop- per is granulated for making brass, by pour- ing it through a perforated ladle into a covered vessel of water with a moveable false bottom. A compound metal, consisting chiefly of lead, is poured into water through a perforated ves- sel of another kind, for making small shot, in whicli the height above the surface of the fluid requires particular adjustment. In a new manufactory of this kind, the height is up- ward of 100 feet. GRAPHIC ORE. An ore of tellurium, occurring in veins in porphyry in Transylvania. It consists, in 100 parts, of 60 tellurium, 30 gold, and 10 silver, by Klaproth. GRAPHITE. Rhomboidal graphite of Jameson, or plumbago, of which he gives two sub-species, the scaly and compact. 1st, Scaly Graphite. Colour dark steel- grey, approaching to iron-black. It occurs massive, disseminated and crystallized. The primitive form is a rhomboid. The second- ary form is the equiangular six-sided table. Lustre splendent, metallic. Cleavage single. Fracture scaly foliated. Streak shining and metallic. Hardness sometimes equal to that of gypsum. Perfectly sectile. Rather difficultly fran- gible. It writes and soils. Streak on paper black. Feels very greasy. Sp. gr. from 1.9 to 2.4. 2d, Compact Graphite. Colour rather blacker than preceding. Massive, disseminat- ed, and in columnar concretions. Internal lustre glimmering and metallic. Fracture small grained uneven, passing into conchoidal. When heated in a furnace, it burns without flame or smoke, forming carbonic acid, and leaving a residuum of iron. Its constituents are, carbon 91, iron 9. Bertholkt. It some- times contains nickel, chromium, manganese, and oxide of titanium. It usually occurs in beds, sometimes disseminated and in imbedded masses, in granite, gneiss, mica- slate, clay- slate, foliated granular limestone, coal and trap formations. ' It is found in gneiss in Glen Strath Farrar in Inverness-shire ; in the coal formation near Cumnock in Ayrshire, where it is -imbedded in greenstone, and in columnar glance-coal. At Borrodale in Cum- berland, it occurs in beds of very varying thick- ness, included in a bed of trap, which is subordinate to clay-slate ; and in many places on the continent, and elsewhere. The finer kinds are first boiled in oil, and then cut into tables for pencils. Grates are blackened with it, and crucibles formed of a mixture of it and clay. Jameson . GRAVEL. See CALCULUS (URINARY). GRAVITY, a term used by physical writers to denote the cause by which aU bodies move toward each other, unless prevented by some other force or obstacle. See AT- TRACTION. GRAVITY (SPECIFIC). See SPE- CIFIC GRAVITY. For the specific gravities of different kinds of elastic fluids, see the table at the article GAS. GREEK FIRE. Asphaltum is supposed to have been its chief constituent, along with nitre and sulphur. GREEN-EARTH. Colour celadine- green, and green of darker shades. Massive, and in globular and amygdaloidal shaped pieces, sometimes hollow, or as in crusting agate balls. Dull. Fracture earthy. Opaque. Feebly glistening in the streak. Soft and sectile. Rather greasy. Adheres slightly to the tongue. Sp. gr. 2.6. Before the blow- pipe it is converted into a black vesicular slag. GUA 511 GUA Its constituents are, silica 53, oxide of iron 28, magnesia 2, potash 10, water 6. It is a frequent mineral in the amygdaloid of Scot- land, England, Ireland, Iceland, and the Faroe Islands. It occurs in Saxony, near Verona, the Tyrol, and Hungary. It is the mountain- green of artists in water colours. Its colour is durable, but not so bright as that from copper. The green-earth of Verona, of which the analysis is given above, is most esteemed. Jameson. I GREENSTONE. A rock of the trap formation, consisting of hornblende and fel- spar, both in the state of grains or small crystals. The hornblende is commonly most abundant, and communicates a green tinge to the felspar. This rock is called Diabase by the French geologists, who name the compact greenstone Aphanite. GREEN VITRIOL. Sulphate of iron. GRENATITE. Prismatoidal garnet ; the staurotide of Hatty. GRENATITE, or prismatic garnet. See STAUROTIDE. GREYWACKE. A mountain formation, consisting of two similar rocks, which alternate with, and pass into each other, called grey- wacke, and grey wacke- slate. The first pos- sesses the characters of the formation. It is a rock composed of pieces of quartz, flinty, slate, felspar, and clay-slate, cemented by a clay- slate basis. These pieces vary in size from a hen's egg to little grains. When the texture becomes exceedingly fine grained, the rock constitutes greywacke-slate. Its colour is usually ash or smoke- grey, without the yel- lowish-grey, or greenish tinge, frequent in primitive slate. It has not the continuous lustre of primitive slate, but glimmers from interspersed scales of mica. It contains quartz veins, but no beds of quartz. Petrifactions are found in it. These rocks are stratified, forming, when alone, round-backed hills, with deep valleys between them. Immense beds of trap, flinty-slate, and transition limestone, are contained in this formation; as well as nu- merous metallic ores in beds and large veins. GROSSULARE. Colour asparagus-green. Crystallizes in acute double eight-sided pyra- mids, flatly acuminated on both extremities by four planes ; the acuminating planes set on the alternate edges of the double eight-sided pyramid. Planes of the crystals smooth, shining- Fracture between conchoidal and uneven. Translucent. Brittle. Occurs im- bedded in small crystals along with vesuvian, in a pale greenish -grey clay-stone near the river Wilui, in Siberia also at the Bannat of Jemeswar. Jameson. GUAIACUM. A resinous looking sub- stance, extracted from the very dense wood of a tree growing in the West Indies, called guaiacum ojficinale. It differs however from resins in its habi- tudes with nitric acid, as Mr. Hatchett first showed. Its sp. gr. is 1.229. Its colour is yellowish-brown, but it becomes green on ex- posure to light It is transparent, and breaks with a resinous fracture. Its odour is not dis- agreeable, but when a very little of its powder, mixed with water, is swallowed, it excites a very unpleasant burning sensation in the fauces and stomach. Heat fuses it, with the exhala- tion of a somewhat fragrant smell. Water dissolves a certain portion of it, ac- quiring a brownish tinge, and sweetish taste. The soluble matter is left when the water is evaporated. It constitutes 9 per cent, of the whole, and resembles what some chemists call extractive. Guaiacum is very soluble in alcohol. This solution, which is brown-coloured, is decom- posed by water. Aqueous chlorine throws down a pale blue precipitate from it. Guaiacum dissolves readily in alkaline leys, and in sulphuric acid ; and in the nitric with effervescence. From the solution in the last liquid, oxalic acid may be procured by eva- poration, but no artificial tannin can be ob- tained, as from the action of nitric acid on the other resins. Guaiacum, distilled in close vessels, leaves 30.5 per cent, of charcoal, being nearly double the quantity from an equal weight of the common resins. From Dr. Wollaston's ex- periments, it would appear that both air and light are necessary to produce the change in guaiacum from yellow to green. And Mr. Brande found that this green colour was more rapidly brought on in oxygen, than in common air. With nitric acid, or chlorine, it becomes green, next blue, and lastly brown. By my analysis Guaiacum is composed, in 100 parts, of carbon 67.88, hydrogen 7.05, oxygen 25.07 ; or, approximately, Carbon 7 atoms 5.25 67-7 Hydrogen 4 0.50 6.5 Oxygen 2 2.00 25.8 7-75 100.0 Formerly guaiacum was much commended in syphilis and other complaints ; at present it is used chiefly in rheumatism, dissolved in liquid ammonia. GUANO. A substance found on many of the small islands in the South Sea, which are the resort of numerous flocks of birds, particu- larly of the ardea and phaenicopteros genus. It is dug from beds 50 or 60 feet thick, and used as a valuable manure in Peru, chiefly for Indian corn. It is of a dirty yellow colour, nearly insipid to the taste, but has a powerful smell partaking of castor and valerian. Ac- cording to the analysis of Fourcroy and Vau- quelin, about one-fourth of it is uric acid, partly saturated with ammonia and lime. It contains likewise oxalic acid, partly saturated with ammonia and potash ; phosphoric acid combined with the same bases and with lime ; small quantities of sulphate and muriate of GUN 512 GYP potash, and ammonia ; a small portion of fat matter; and sand, partly quartzose, partly ferruginous. GUM. The mucilage of vegetables. The principal gums are, I. The common gums, obtained from the plum, the peach, the cherry tree, &c. 2. Gum Arabic, which flows na- turally from the acacia in Egypt, Arabia, and elsewhere. This forms a clear transparent mucilage with water. 3. Gum Seneca, or Senegal. It does not greatly differ from gum Arabic ; the pieces are larger and clearer ; and it seems to communicate a higher degree of the adhesive quality to water. It is much used by calico-printers and others. The first sort of gums are frequently sold by this name, but may be known by their darker colour. 4. Gum Adragant or Tragacanth. It is ob- tained from a small plant of the same name growing in Syria, and other eastern parts. It comes to us in small white contorted pieces resembling worms. It is usually dearer than other gums, and forms a thicker jelly with water. Mr. Willis has found, that the root of the common blue-bell, hyacinthus non scriptus, dried and powdered, affords a mucilage pos- sessing all the qualities of that from gum Arabic. Lord Dundonald has extracted a mucilage also from lichens. Gums treated with nitric acid afford the acid of sugar. I found Gum Arabic to consist of carbon 35.1 3, hydrogen 0.08, oxygen 55.79, azote 3 ? GUM (ELASTIC). See CAOUTCHOUC. GUM RESIN. The principal gum resins are frankincense, scammony, asafcetida, aloes, gum ammoniac, and gamboge. GUNPOWDER. This well known pow- der is composed of 75 parts, by weight, of nitre, 16 of charcoal, and 9 of sulphur, inti- mately blended together by long pounding in wooden mortars, with a small quantity of water. This proportion of the materials is the most effectual. But the variations of strength in different samples of gunpowder are gene- rally occasioned by the more or less intimate division and mixture of the parts. The rea- son of this may be easily deduced from the consideration, that nitre does not detonate until in contact with inflammable matter ; whence the whole detonation will be more speedy, the more numerous the surfaces of contact. The same cause demands, that the ingredients should be very pure, because the mixture of foreign matter not only diminishes the quan- tity of effective ingredients which it represents, but likewise prevents the contacts by its inter- position. The nitre of the third boiling is usually chosen for making gunpowder, and the char- coal of light woods is preferred to that of those which are heavier, most probably because this last, being harder, is less pulverable. The requisite pounding of the materials is performed in the large way by a mill, in which wooden mortars are disposed in rows, and in each of which a pestle is moved by the arbor of a water-wheel : it is necessary to moisten the mixture from time to time with water, which serves to prevent its being dissipated in the pulverulent form, and likewise obviates the danger of explosion from the beat occa- sioned by the blows. Twelve hours' pounding is in general required to complete the mixture ; and when this is done, the gunpowder is in fact made, and only requires to be dried to render it fit for use. The granulation of gunpowder is performed by placing the mass, while in the form of a stiff paste, in a wire sieve, covering it with a board, and agitating the whole : by this means it is cut into small grains or parts, which, when of a requisite dryness, may be rendered smooth or glossy by rolling them in a cylin- drical vessel or cask. Gunpowder in this form takes fire more speedily than if it be afterward reduced to powder, as may be easily accounted for from the circumstance, that the inflamma- tion is more speedily propagated through the interstices of the grams. But the process of granulation does itself, in all probability, weaken the gunpowder, in the same manner as it is weakened by suffering it to become damp ; for, in this last case, the nitre, which is the only soluble ingredient, suffers a partial solu- tion in the water, and a separation in crystals of greater or less magnitude; and accordingly the surfaces of contact are rendered less nu- merous. Berthollet found, that the elastic product afforded by the detonation of gunpowder, con- sisted of two parts nitrogen gas, and one car- bonic acid gas. The sudden extrication and expansion of these airs are the cause of the effects of gunpowder. GURHOFITE. Compact Dolomite, which occurs in veins in serpentine rocks, between Gurhof and Aggsbach, in Lower Austria. GYPSUM. This genus contains 2 species, by Professor Jameson ; the prismatic, and the axifrangible. I Prismatic gypsum or anhydrite. Mu- riacit. Werner. Of this there are 5 sub- species. 1. Sparry anhydrite. See Cube-STAJL. 2. Scaly anhydrite. Colour white of various shades passing into smalt-blue. Massive, and in granular concretions. Lustre splendent, pearly. Cleavage imperfect and curved. Trans- lucent on the edges. Easily broken. Sp. gr. 2.96. Its constituents are, lime 41-75, sul- phuric acid 55, mur. of soda 1-0. It is found in the salt mines of the Tyrol, 5088 feet above the level of the sea. 3. Fibrous anhydrite. Colours, red, blue, and grey. Massive, and in coarse fibrous con- cretions. Lustre glimmering and pearly. Translucent on the edges. Rather easily frangible. Spec. grav. 3. It is found in the GYP 513 GYP salt mines on the continent. The blue is sometimes cut into ornaments. 4. Convoluted anhydrite. Colour, dark milk-white. Massive, and in distinct con- cretions. Lustre glimmering and pearly. Frac- ture fine splintery. Translucent on the edges. Sp. gr. 2.85. Its constituents are, 42 lime, 5(>-5 sulphuric acid, 0-25 muriate of soda. It occurs in the salt mines of Bochnia, and at Wieliczka in Poland. It has been called pierre de tripes, from its convoluted concre- tions. 5. Compact anhydrite. Colour grey, some- times with spotted delineations. Massive, and in distinct granular concretions. Feebly glim- mering. Fracture small splintery. Trans- lucent. Hardness and constituents as in the preceding. Sp. gr. 2-95. II. Axifrangible gypsum. This species contains, according to Professor Jameson, 6 sub-species ; sparry gypsum, fo- liated, compact, fibrous, scaly foliated, and earthy gypsum. 1. Sparry gypsum or selcnite. Colours, grey, white, and yellow, with occasional iri- descence. Massive, disseminated, and crystal- lized. Its primitive form is an oblique four- sided prism, with angles of 1 13 8' and 66 52'. The following are some of the secondary forms. 1. Six-sided prism, generally broad, and oblique angular, and four smaller lateral planes. 2. Lens. 3. Twin crystals, formed either by two lenses, or by two six-sided prisms, pushed into each other in the direc- tion of their breadth. 4. Quadruple crystal, from two twin crystals pushed into each other in the direction of their length. Lustre splen- dent, pearly. Cleavage threefold. Fragments rhomboidal. Semitransparent, and transpa- rent. Refracts double. Yields to the naiL Scratches talc, but not calcareous spar. Sec- tile. Easily frangible. In thin pieces flexi- ble, but inelastic. Sp. gr. 2-3. It exfoliates and melts into a white enamel, which falls into a white powder. Its constituents are, 33-9 lime, 43-9 sulphuric acid, 21 water, and 2-1 loss; Bucholz. It occur* principally in the floetz gypsum formation in thin layers ; less frequently in rock salt ; frequently in the London blue clay. Crystals are daily forming n gypsum hills, and in old mines. It is found n blue clay, at Shotover-hill, near Oxford ; Newhaven, Sussex; around Paris, and all )ver the continent. It was used in ancient imes for window glass. Hence it was called ;lacies marife, and lapis specularis. 2. Foliated granular gypsum. Colours, vhite, grey, and red ; sometimes in spotted or triped delineations. Massive, and in distinct concretions, or crystallized, in small conical lenses. Lustre, glistening, pearly. Cleavage as selenite. Translucent Very soft, sectile and easily frangible. Sp. gr. 2-3. Its con- stituents are, 32 lime, 30 sulphuric acid, and 38 water, according to Kirwan. It occurs in beds in primitive rocks, as gneiss and mica- slate ; in transition clay-slate ; but most abun- dantly in beds in the rocks of the floetz class. It is there associated with selenite, compact gypsum, fibrous gypsum, rock-salt, stinkstone, and limestone. It is found in Cheshire and Der- byshire, at Luneburg, and other places on the continent. The foliated and compact gypsums, when pure and capable of receiving a good polish, are termed alabaster by artists, who fashion them into statues and vases. The coarser kinds are used in small quantities in agriculture ; and are converted by calcination into stucco. 3. Compact gypsum. Colours, white of va- rious shades, grey, blue, red, and yellow. Massive. Dull. Fracture fine splintery. Translucent on the edges. Soft, sectile, and easily frangible. Sp. gr. 2-2. Its consti- tuents are, 34 lime, 48 sulphuric aid, 18 water Gerhard. It occurs in beds, along with granular gypsum, &c. It is found in the Campsie hills ; in Derbyshire ; at Ferry- bridge, Yorkshire, and in various places on the Continent. 4. Fibrous gypsum. Colours white, grey, and red. Massive and dentiform, and in fibrous distinct concretions. Lustre glisten- ing and pearly. Translucent. Soft, sectile, and easily frangible. Its constituents are, 33 lime, 44-13 sulphuric acid, 21 water. It occurs along with the other sub-species, in red sandstone near Moffat ; in the Forth river near Belfast ; in Cumberland, Yorkshire, Cheshire, &c. When cut en cabachon, and polished, it re- flects a light, not unlike that of the cat's-eye, and is gometimes sold as that stone. 5. Scaly foliated gypsum. Colour white. Massive, disseminated, and in distinct concre- tions. Lustre, glistening and pearly. Frac- ture small scaly foliated. Opaque, or trans- lucent on the edges. Soft, passing into fri- able. Sectile and easily frangible. It occurs along with selenite, at Montmartre, near Pa- ris, in the third floetz formation of Werner. 6. Earthy gypsum. Colour yellowish- white. Composed of fine scaly or dusty par- ticles. Feebly glimmering. Feels meagre or rather fine. Soils slightly. Light. It is~ found immediately under the soil, in beds several feet thick, resting on gypsum, in Saxony, Switzerland, and Norway. Jameson. HEA 514 HEA H HAEMATITES. An ore of iron. HAIR. From numerous experiments M. Vauquelin infers, that black hair is formed of nine different substances, namely : 1. An animal matter, which constitutes the greater part. 2. A white concrete oil in small quantity. 3. Another oil of a greyish-green colour, more abundant than the former. 4. Iron, the state of which in the hah: is uncer- tain. 5. A few particles of oxide of manga- nese. 6. Phosphate of lime. 7. Carbonate of lime, in very small quantity. 8. Silex, in a conspicuous quantity. 9. Lastly, a con- siderable quantity of sulphur. The same experiments show, that red hair differs from black only in containing a red oil instead of a blackish-green oil ; and that white hair differs from both these only in the oil being nearly colourless, and in containing phosphate of magnesia, which is not found in them. HARMOTOME. CROSS-STONE. HARTSHORN (SPIRIT OF). See AMMONIA. HATCHETINE A variety of bitu- minous matter found in the iron-stone Mez- thyr Tydfil, in South Wales. Colour yellow- ish-white. Texture flaky or subgranular ; in the former the lustre is glistening, in the latter dull. Hardness of soft tallow. Inelastic, and inodorous. Melts at 170. It is very light. Soluble in ether. . Hatchetine is found filling small contemporaneous veins, lined with calcareous spar and small rock crystals, in the iron-stone. Mr. J. J. Conybeare, in Annals of Phil. N. i. 136. HAUYNE. Colour blue of various shades. It occurs imbedded in grains, and rarely crys- tallized ; in acute oblique double four-sided pyramids, variously truncated. Externally it is generally smooth, and edges rounded. Lustre splendent, to glistening, and vitreous. Cleavage quintuple. Fracture imperfect con- choidal. Transparent and translucent Harder than apatite, but softer than felspar. Brittle. Easily frangible. Sp. gr. 2-7- It melts with difficulty before the blowpipe, into a white nearly opaque vesicular bead. With borax it melts into a transparent wine-yellow glass. With acids it forms a transparent jelly. Its constituents are, silica 30, alumina 15, lime 13.5, sulphuric acid 12, potash 11, iron 1, loss 17-5. Vauquelin. But by Gmelin, we have silica 35-48, alumina 18 87, lime 11-79, sulphuric acid 12-6, potash 15-45, iron 1-16, loss 3-45. It occurs imbedded in the basalt rock of Albano and Frescati. Professor Jameson thinks it nearly allied to azure-stone. HEAVY SPAR. Baryte. This genus is divided by Professor Jameson into four species; rhomboidal, prismatic, diprismatic, and axifrangible. 1. Rhomboidal laryte, or Witherite. Co- lours white, grey, and yellow. Massive. Disseminated in various imitative shapes, and crystallized. The primitive form is a rhom- boid of 88 6' and 91 54'. The secondary forms are, the equiangular six-sided prism, truncated, or acutely acuminated, and the acute double six-sided pyramid. Prisms sco- piformly grouped, or in druses. Lustre glist- ening, and resinous. Cleavage threefold. Prin- cipal fracture uneven. Translucent. Harder than calcareous spar. Easily frangible. Sp. gr. 4-3. Before the blowpipe it decrepitates slightly, and melts readily into a white enamel ; soluble with effervescence in dilute nitric acid. It is carbonate of barytes, with occasionally 1 per cent, of carbonate of strontites and sul- phate of barytes. It occurs in Cumberland and Durham in lead veins that traverse a secondary limestone, which rests on red sand- stone. It is an active poison, and is employed for killing rats. 2. Prismatic laryte, or Heavy spar. Of this there are nine sub-species ; earthy, com- pact, granular, curved lamellar, straight la- mellar, fibrous, radiated, columnar, and prismatic. They are all sulphates of barytes in composition. On account of its forms of crys- tallization, we shall describe the fresh, straight, lamellar, heavy spar. Its colours are white, grey, blue, green, yellow, red, and brown. Massive, in distinct concretions, and crystallized. The primitive form is an oblique four-sided prism of 101 53'. The following are the secondary forms : the rectangular four-sided table ; the oblique four-sided table, perfect or variously trun- cated or bevelled ; the longish six-sided table, perfect or bevelled ; the eight-sided table, per- feet or bevelled. Lustre splendent, between resinous and pearly. Cleavage parallel with the planes of the primitive prism. Fragments rhomboidal and tabular. Translucent or trans- parent, and refracts double. Scratches cal- careous spar, but is scratched by fluor spar. Brittle. Sp. gr. 4-1 to 4-C. It decrepitates briskly before the blowpipe, and then melts into a white enamel. It phosphoresces on glowing coals with a yellow light. It is sulphate of barytes, with 0.85 sulphate of strontites, and 0-80 oxide of iron. It is found almost always in veins, which occur in granite, gneiss, mica-slate, and other rocks. The flesh- red variety is often accompanied with valuable ores. In Great Britain, it occurs in veins of different primitive and transition rocks, and in secondary limestone, &c. in the lead mines of Cumberland, Durham, and Westmoreland. 3. Diprismatic laryte, or Strontianite. HED 515 HEM Colour pale asparagus-green, yellowish, white, and greenish-grey. Massive, in dis- tinct concretions, and crystallized. The pri- mitive form is an oblique four-sided prism, bevelled on the extremities. Secondary figures are, the acicular six-sided prism, and the aci- cular acute double six-sided pyramid. Lustre glistening or pearly. Cleavage, in the direc- tion of the lateral planes of the primitive form. Fracture fine-grained, uneven. Translucent. Harder than calcareous spar, but softer than fluor. Brittle. Sp. gr. 3-7. Infusible before the blowpipe, but becomes white and opaque, tingeing the flame of a dark purple colour. It is soluble with effervescence in dilute nitric or muriatic acid ; and paper dipped in the solu- tions thus produced burns with a purple flame. Its constituents are, Strontian, 61-21 69-5 62-0 74-0 Carbonic acid, 30-20 30-0 30-0 25-0 Water, 8.50 0-5 8-0 0-5 100-0 100-0 100-0 100-0 Hope. Klapr. Pclle. Bucholz. It occurs at Strontian in Argyllshire, in veins that traverse gneiss, along with galena, heavy spar, and calcareous spar. traces of benzole acid. An extremely mi- nute quantity of benzoate of ammonia, treated in the same way, for comparison, gave the characteristic crystals of that acid. The other portion was added to a neutral solution of red muriate of iron, but no precipitate ensued. A very small particle of crystallized benzoate of ammonia being added to the same muriate, speedily gave the brown precipitate, but pro- duced no change whatever on solutions, perfectly neutral, of the green muriate and sulphate ; a fact of consequence to show the state of oxi- dizement, in which iron exists in a mineral or saline combination, indicating also an easy method of separating the two oxides of this metal. From the above experiments we may infer, with much probability, that the concre- tion contains no benzoic acid. Nitric acid, sp. gravity 1.300, digested on it at a gentle heat, and then cooled, converted the substance into bright yellow globules, denser and less friable than the original matter, and somewhat semitransparent, like impure rosin. There was, however, no true solution by the acid ; nor was the combusti- bility in the least impaired, by the operation. As our Institution possesses specimens of very fragrant ambergris, said to have been im- ported in the genuine state from Persia, I was desirous to compare their chemical relations with those of this morbid concretion. Two of the pieces of ambergris differ in many respects from one another. The first is of a light grey colour, with resinous looking points inter- spersed through it, and has a density con- siderably greater than water. It is 1.200. When heated in water to the temperature of 130, it falls down into light spongy fragments. The second has a specific gravity of 0.959 ; it is darkish brown on the outside, and light brown within. In water heated to the above degree, it softens into a viscid substance like treacle. Both are readily dissolved in warm alcohol, but the latter yields the richer golden- coloured solution. As the alcohol cools, a se- paration of brilliant scales is perceived. With ether, naphtha, the fixed and volatile oils, the phenomena exhibited by ambergris are abso-- lutely the same as those presented by the con- cretion with these solvents. The alcoholic solution mixed with liquid ammonia gives a similar milky emulsion. The lighter specimen of ambergris, exposed to a gentle heat over a lamp, in a glass tube sealed at one end, fuses, and evolves a volatile oil in dense vapour, which is condensed on th% upper part of the tube. A viscid substance like tar remains at the bottom. The oil re- sembles the succinic, and has, like it, a dis- agreeable empyreumatic odour. The denser ambergris, being subjected to heat in like cir- cumstances, fuses less readily and completely, emits the .same volatile empyreumatic oil, ac- companied with crystalline needles, decidedly acidulous. These are either the benzoic or succinic acid. They precipitate peroxide of iron from the neutral red muriate. The smell of the accompanying oil is certainly that of amber ; but I have hitherto obtained too small quantities of the acid, to be able to de- termine to which of the two it belongs. The following experiments were made with this view. My first object was to discover a good criterion for discriminating benzoic from suc- cinic acid. In operating necessarily on small quantities, the distinction becomes peculiarly difficult. Both are volatile, crystallizable, and fall down with peroxide of iron, from saline solutions of this metal. After many trials I finally fell on the following plan, which an- swers very well, even with pretty minute por- tions. I saturated each acid with ammonia, evaporated to a dry crystalline mass by a gentle heat. Into a small glass tube, sealed at one end, I introduced a portion of the ben- zoate. The tube was recurved. I exposed the bottom, where the salt was placed, to the heat of a lamp, but very cautiously. Pungent ammoniacal gas was exhaled, and the water of crystallization that distilled over was found strongly impregnated with ammonia. To avoid all fallacy in this result, I slightly supersatu- rated the ammonia beforehand with the acid. In the middle of the tube, pure benzoic acid was found, in acicular crystals. The succinate of ammonia, on the contrary, sublimes without decomposition. I now took a few grains of the dense am- bergris, digested with alcohol, added water of ammonia, boiled, filtered, and evaporated to dryness. The quantity of saline matter ob- tained was, however, too minute, even for the above mode of applying an analytical cri- terion with satisfaction ; and being unwilling to consume more than a few grains of a speci- men belonging to a public establishment, I preferred waiting till some future opportunity might occur of examining genuine ambergris. From the lighter, and by its outward ap- pearance, more characteristic specimen of am- bergris, I could not obtain even a trace of ben- zoic acid, though I modified the temperature for sublimation, and other circumstances, in every way I could think of. The oil that rose would not redden the most delicate litmus paper. In open capsules, fragments of the amber- gris, being exposed to a pretty strong heat, exhaled the copious subfoetid smoke ; and afterwards burned with the yellow flame ex- hibited by the concretion. Fragments of the concretions, exposed to heat in a glass tube, fused, envolved the heavy smoke, which con- densed into a viscid empyreumatic smelling oil, and in every respect comported itself like the light ambergris. I therefore must infer it to be a modification of ambergris. It differs decidedly from the adipbcere of dead bodies, which forms an emul- sion with cold water, is fusible in boiling water. INU 529 IOD gives a soap with evolution of ammonia when treated with potash, and yields a clear solution , when gently heated, with liquid ammonia. It resembles, however, in many respects, the cholesterine of biliary calculi ; and I have no doubt that cholesterine from altered bile is the true origin of ambergris in the whale, as well as of this morbid concretion. The concretion is almost wholly soluble in hot alcohol ; while only one- third of adipocere dissolves in that menstruum at the boiling point. From ordinary fatty matter it is entirely distinguishable, by its solubility in ether and alcohol, its refusing to combine with alkalis, and the high temperature required for its fusion. With regard to their place of formation in the animal system, \mbergris and this morbid concretion agree. They are both generated in the rectum, or greater intestines. The physeter macrocephalus of Linnaeus is the species of whale which affords ambergris. In the ex- amination of Captain Coffin before the Privy- Council in 1791, he stated that he found 362 ounces of ambergris in the intestines of a fe- male whale, struck off the coast of Guinea ; part of it was voided from the rectum on cutting up the blubber, and the remainder was within the intestinal canal. The whales that contain ambergris are said to be always lean and sickly, yield but very little oil, and seem almost torpid. Hence, when a spermaceti whale has this appearance, and does not emit feces on being harpooned, the fishers generally expect to find ambergris within it. Whether it be the cause or the effect of disease is problematical, though the latter seems the more rational conjecture. It may in succession be both. The above re- markable fact of the sex of the whale may lead to an inquiry, whether this morbid pro- duction, found also in the human subject, be peculiar to females, and connected with lac- tation. In the second volume of Dr. Monro's Out- lines of the Anatomy of the Human Body in its sound and diseased state, we have the ana- lysis of several alvine concretions by Dr. Thomas Thomson. The results obtained by this eminent chemist show, that the specimens which he examined were of a totally different nature from the preceding concretion. 1NULIN. In examining the Inula Hel- lenium, or Elecampane, Mr. Rose imagined he discovered a new vegetable product, to which the name of Inulin has been given. It is white and pulverulent like starch. When thrown on red-hot coals, it melts, diffusing a white smoke, with the smell of burning sugar. It yields, on distillation in a retort, all the products furnished by gum. It dis- solves readily in hot water ; and precipitates almost entirely on cooling, in the form of a white powder; but before falling down, it gives the liquid a mucilaginous consistence. It precipitates quickly on the addition of al- cohol. The above substance is obtained by boiling the root of this plant in four times its weight of water, and leaving the liquid in repose. MM. Pelletier and Caventou have found the same starch-like matter in abundance in the root of colchicum ; and M. Gautier in the root of pellitory. Starch and imiline combine ; and when the former is in excess, it is difficult to se- parate them. The only method is to pour infu- sion of galls into the decoction, and then to heat the liquid : if inulin be present, a precipitate will fall, which does not disappear till the tem- perature rises to upwards of 212 F., while, if only starch be present, it will redissolve at 122 F. IODINE. A peculiar or undecompounded principle. The investigation of this singular substance will always be regarded as a great era in chemistry. It was then that chemical philosophers first felt the necessity of abandon- ing Lavoisier's partial and incorrect hypothesis of oxygenation, and of embracing the sound and comprehensive doctrines of Sir H. Davy on chemical theory, first promulgated in his masterly researches on Chlorine. Iodine was accidentally discovered in 1812, by M. de Courtois, a manufacturer of salt- petre at Paris. In his processes for procuring soda from the ashes of sea- weeds, he found the metallic vessels much corroded ; and in search- ing for the cause of the corrosion, he made this important discovery. But for this circumstance, nearly accidental, one of the most curious of substances might have remained for ages un- known, since nature has not distributed it, in either a simple or compound state, through her different kingdoms, but has stored it up to what the Roman satirist considers as the most worthless of things, the vile sea- weed. Iodine derived its first illustration from MM. Clement and Desormes, names associ- ated always with sound research, In their memoir, read at a meeting of the Institute, these able chemists described its principal pro- perties. They stated its sp. gr. to be about 4 ; that it becomes a violet-coloured gas at a tem- perature below that of boiling water; whence its name, 'IwS*;?, like a violet* was .derived ; that it combines with the metals, and' with phosphorus and sulphur, and likewise with the alkalis and metallic oxides ; that it forms a detonating compound with ammonia ; that it is soluble in alcohol, and still more soluble in ether ; and that by its action upon phos- phorus, and upon hydrogen, a substance hav- ing the characters of muriatic acid is formed. In this communication they offered no decided opinion respecting its nature. In 1813 Sir H. Davy happened to be on a visit to Paris, receiving, amid the political convulsions of France, the tranquil homage due to his genius. " When M. Clement IOD 530 IOD showed iodine to me, he believed that the hy- driodic acid was muriatic acid ; and M. Gay Lussac, after his early experiments, made originally with M. Clement, formed the same opinion, and maintained it, when I first stated to him my belief, that it was a new and pe- culiar acid, and that iodine was a substance analogous in its chemical relations to chlorine." Sir fJ. Davy on the Analogies between the un- decompounded substances ; Journal of Science and the Arts, vol. i. p. 284. We see therefore with what intuitive sa- gacity the English philosopher penetrated the mystery which hung at first over iodine. Its full examination, in its multiplied relations to simple and compound bodies, was immediately entered on with equal ardour by him and M. Gay Lussac. Of the relative merits of the researches, and importance of the results, of these pre-eminent chemists, it is not for me to become an arbiter. I shall content myself with offering a methodical view of the facts brought to light on iodine and the iodides, re- ferring for its other combinations to what I have already stated on the hydriodic and iodic acids. Iodine has been found in the following sea- weeds, the algaa aquaticae of Linnaeus : Fucus cartilagineus, Fucus palmatus, membranaceus, filum, filamentosus, digitatus, rubens, saccharimus, nodosus, Ulva umbilicalis, serratus, pavonia, siliquosus, linza, and in sponge. Dr. Fyfe has shown, in an ingenious paper, published in the first volume of the Edin. Phil. Journal, that on adding sulphuric acid to a concentrated viscid infusion of these algee in hot water, the vapour of iodine is exhaled. M. Angelina on using starch as a reagent, with the mineral water of Sales in Piedmont, found a blue colour produced in the water, indicating iodine ; and he afterwards succeeded in procuring iodine from the water. It is re- markable that for a long time that water has been administered successfully in scrofulous cases, and in cases of the goitre. Journ. dcs Mines, viii. 293. M. Cantu of Turin found iodine in the sulphureous mineral waters of Castelnuovo d'Asti. He thinks that iodine exists in all the mineral waters that contain chlorides. Yet the sulphureous mineral water of Echaillon in Savoy that yields -^ its weight of common salt contains no iodine. Ann. de Chirn., xxviii. 221. M. Balard gives the following as the best means of testing for iodine. After mixing the liquid containing iodine, with the starch and sulphuric acid, a small quantity of aqueous solution of chlorine is to be added, which from its lightness may be kept floating on the sur- face. At the place where the two liquids touch, a blue zone will be perceived, which, however feeble it may be, is readily seen by contrast with the adjoining colourless liquids. The colour disappears on agitation, if the chlorine be in excess. By means of this test M. Balard has found iodine, in various marine molluscae, testaceous or not, such as the doris, venus, oysters, fyc., in many polypi and marine vegetables, thegorgonia, the zoster marina, to 230; and by the thermometer, all the intervening de- grees may certainly be ascertained." Brandes Manual, ii. 132. III. Salts of iron. These salts have the following general cha- racters : 1. Most of them are soluble in water; those with the protoxide for a base are gene- IRQ IRQ rally crystallizable ; those with the peroxide are generally not; the former are insoluble, the latter soluble in alcohol. 2. Ferroprussiate of potash throws down a blue precipitate, or one becoming blue in the air. 3. Infusion of galls gives a dark purple precipitate, or one becoming so in the air. 4. Hydrosulphuret of potash or ammonia gives a black precipitate; but sulphuretted hydrogen merely deprives the solutions of iron of their yellow-brown colour. 5. Phosphate of soda gives a whitish pre- cipitate. 6. Benzoate of ammonia, yellow. 7 Succinate of ammonia, flesh-coloured with the peroxide. 1. P rot acetate of iron forms small prisma- tic crystals, of a green colour, a sweetish styptic taste, and a sp. gr. 1-368. 2. Pcracetatc of iron forms a reddish-brown uncrystallizable solution, much used by the calico-printers, and prepared by keeping iron turnings, or pieces of old iron, for six months immersed in redistilled pyrolignous acid. See ACID (ACETIC). 3. Protarscniate of iron exists native in crystals, and may be formed in a pulverulent state, by pouring arseniate of ammonia into sulphate of iron. It is insoluble, and consists, according to Chenevix, of 38 acid, 43 oxide, and 19 water, in 100 parts. 4. Perarseniate of iron may be formed by pouring arseniate of ammonia into peracetate' of iron ; or by boiling nitric acid on the protar- seniate. It is insoluble. 5. Antimoidate of iron is white, becoming yellow, insoluble. 6. Boratc, pale yellow, insoluble. 7- Benzoate, yellow, insoluble. 8. Protocai bonate, greenish, soluble. 9. Percarbonate, brown, insoluble. 10. Chromate, blackish, do. 11. Protocitrate, brown crystals, soluble. 12. Protoferroprussiate, white, insoluble. 13. Perferroprussiate, blue, do. This constitutes the beautiful pigment called prussian blue. When exposed to a heat of about 400, it takes fire in the open air; but in close vessels it is decomposed, apparently, into carburetted hydrogen, water, and hydro- cyanate of ammonia, which come over ; while a mixture of charcoal and oxide of iron re- mains in the state of pulverulent pyrophorus, ready to become inflamed with contact of air. I have already considered the constitution of prussian blue, in treating of the ACID (FEH- ROPRUSSIC) ; and have little farther to add to what is there stated. When sulphuric acid is added to prussian blue, it makes it perfectly white, apparently by abstracting its water ; for the blue colour returns on dilution of the acid, and if the strong acid be poured off, it yields no traces of either prussic acid or iron. On submitting pure prussian blue for some time to the action of sulphuretted hydrogen water, small brilliant crystals of a yellowish colour appeared, which became blue in the air, and were protoprus- siate of iron. 14. Protogallate, colourless, soluble. 15. Pergallatc, purple, insoluble. 16. Protornuriate, green crystals, very so- luble. 17. Permuriate, brown, uncrystallizable, very soluble. See the chlorides of iron pre- viously described. 18. Protonitrate, pale green, soluble. 19. Pernitrate, brown, do. 20. Protoxulate, green prisms, do. 21. Peroxalate, yellow, scarcely soluble. 22. Protophosphate, blue, insoluble. 23. Pcrphosphate, white, do. 24. Protosuccinate, brown crystals, solu- ble. 25. Persuccinate, brownish-red, insoluble. 26. Protosnlphate, green vitriol, or cop- peras. It is generally formed by exposing native pyrites to ah- and moisture, when the sulphur and iron both absorb oxygen, and form the salt. There is, however, an excess of sulphuric acid, which must be saturated by digesting the lixivium of the decomposed pyrites with a quantity of iron plates or turn- ings. It forms beautiful green crystals, which are transparent rhomboidal prisms, whose faces are rhombs with angles of 7i> 50' and 100 10', inclined to each other at angles of 98 3/' and 8 IP 23'. Sp.gr. 1-84. Its taste is harsh and styptic. It reddens vegetable blues. Two parts of cold and three-fourths of boiling water dissolve it. It does not dissolve in alco- hol. Exposure to air converts the surface of the crystals into areddeutosulphate. A mode- rate heat whitens it, by separating the water of crystallisation, and a stronger heat drives off the sulphuric acid. Its constituents are 28-9 acid, 28.3 protoxide, and 45 water, ac- cording to Berzelius. 27. Persulphate. Of this salt there seems to be four or more varieties, having a ferreous base. The tartrate and pertartrate of iron may also be formed ; or, by digesting cream of tartar with water on iron filings, a triple salt may be obtained, formerly called tartarized tincture of Mars. See SALT. Iron is one of the most valuable articles of the mateiia medica. The protoxide acts as a genial stimulant and tonic, in all cases of chro- nic debility not connected with organic conges- tion or inflammation. It is peculiarly effica- cious in chlorosis. It appears to me that the peroxide and its combinations are almost uni- formly irritating, causing heartburn, febrile heat, and quickness of pulse. Many chaly- beate mineral waters contain an exceedingly minute quantity of protocarbonate of iron, and yet exercise an astonishing power in rceruiri: ISI 546 IVO the exhausted frame. I believe their virtue to be derived simply from the metal being oxi- dized to a minimum, and diffused by the agency of a mild acid through a great body of water, in which state it is rapidly taken up by the lacteals, and speedily imparts a ruddy hue to the wan countenance. 1 find that these qualities may be imitated exactly, by dissolv- ing 3 grains of sulphate of iron, and 61 of bicar- bonate of potash, in a quart of cool water, with agitation in a close vessel. IRON-FLINT. Eeisenkiesel. Werner. Colours brown and red. Massive and crystal- lized in small equiangular six-sided prisms, acuminated on both extremities. It occurs commonly in small angulo-granular distinct concretions. Lustre vitreo-tesinous. Frac- ture small conchoidal. Opaque. Gives sparks with steel. Rather difficultly frangible. Sp. gr. 2.6 to 2.8. Infusible. Its constituents are, 1)3.5 silica, 5 oxide of iron, and 1 volatile mat- ter. The red iron-flint contains 21.7 oxide of iron, and 76.8 silica. It occurs in veins in ironstone, and in trap-rocks, near Bristol, in the island of Rathlin, at Dunbar, and in many parts of Germany Jameson. IRON-ORE. See ORES of iron. 1SATIS T1NCTORIA. The plant used for dyeing, called wood. ISERINE. Colour iron-black. In small obtuse angular grains. Lustre splendent or glistening, and metallic. Fracture conchoidal. Opaque. Harder than felspar. Brittle. Retains its colour in the streak. Sp.gr. 4-6. It melts into a blackish-brown glass, which is slightly attracted by the magnet. The mineral acids have no effect on it, but oxalic acid extracts a pertion of the titanium. Its constituents are, 48 oxide of titanium, 48 oxide of iron, and 4 uranium, by Dr. Thomson's analysis of the iserine found in the bed of the river Don, in Aberdeenshire; but, by Klaproth, it consists of 28 oxide of titanium, and 72 oxide of iron. On the continent it has hitherto been found only in the lofty Riesengebirge, near the origin of t!i3 stream called the Iser, disseminated in gra- iiite sand; and in alluvial soil along with pyrope in Bohemia.- Jameson. ISINGLASS. This substance is almost wholly gelatin ; 100 grains of good dry isin- glass containing rather more than 98 of mat- ter soluble in water. Isinglass is made from certain fish found in the Danube, and the rivers of Muscovy. Wil- loughby and others inform us that it is made of the sound of the beluga; and Neumann that it is made of the huso Germanorum, and other fish, which he has frequently seen sold in the public markets of Vienna. Mr. Jack- son remarks, that the sounds of cod. properly prepared, afford this substance; and that the lakes of America abound with fish from which the very finest sort may be obtained. Isinglass receives its different shapes in the following manner : The parts of which it is composed, particu- larly the sounds, are taken from the fish while sweet and fresh, slit open, washed from their slimy sordes, divested of a very thin membrane which envelopes the sound, and then exposed to stiffen a little in the air. In this state they are formed into rolls about the thickness of a finger, and in length according to the intended size of the staple : a thin membrane is gene- rally selected for the centre of the roll, round which the rest are folded alternately, and about half an inch of each extremity of the roll is turned inwards. Isinglass is best made in the summer, as frost gives it a disagreeable colour, deprives it of weight, and impairs its gelatinous prin- ciples. Isinglass boiled in milk forms a mild nutri- tious jelly, and is thus sometimes employed medicinally. This, when flavoured by the art of the cook, is the blanc-manger of our tables. A solution of isinglass in water, with a very small proportion of some balsam, spread on black silk, is the court-plaster of the shops. IVORY. The tusk, or tooth of defence of the male elephant. It is an intermediate sub- stance between bone and horn, not capable of being softened by fire, not altogether so hard and brittle as bone. Sometimes it grows to an enormous size, so as to weigh near two hundred pounds. The entire tooth is of a yellowish, brownish, and sometimes a dark brown colour on the outside, internally white, hollow towards the root, and so far as was inserted into the jaw, of a blackish - brown colour. The finest, whitest, smoothest, and most compact ivory comes from the island of Ceylon. The grand consumption of this commodity is for making ornamental utensils, mathematical instru- ments, cases, boxes, balls, combs, dice, and an infinity of toys. The workmen have methods also of tingeing it of a variety of colours. Merat Guillot obtained from 100 parts of ivory, 24 gelatin, 04 phosphate of lime, and 0.1 carbonate of lime. The coal of ivory is used in the arts under the denomination of ivory black. Particular vessels are used in the manufactory of this pigment, for the purpose of rendering it per- fectly black. Some travellers speak of the tooth of the sea-horse as an excellent ivory ; but it is too hard to be sawed or wrought like ivory. It is used for making artificial teeth. KIL 5*7 KUP K KALI. See POTASH. KAOLIN. The Chinese name of porce- lain clay. KARPHOLITE. A yellow mineral, which occurs in thin prismatic concretions. Specific gravity, 2.935. KEDRIA TERRESTRIS. Barbadoes tar. See BITUMEN. KELP. Incinerated sea -weed. See SODA. KERATE. The third mineral order of Mohs. See MINERALOGY. KERMES (coccus illicis, Lin.) is an in- sect found in many parts of Asia, and the south of Europe. On account of their figure, they were a long time taken for the seeds of the tree on which they live ; whence they were called grain* of kermes. They also bore the name of ver- milion. To dye spun worsted with kermes, it is first boiled half an hour in water with bran, then two hours in a fresh bath with one-fifth of Roman alum, and one-tenth of tartar, to which sour -water is commonly added ; after which it is taken out, tied up. in a linen bag, and carried to a cool place, where it is left some days. To obtain a full colour, as much kermes as equals three-fourths, or even the whole of the weight of the wool, is put into a warm bath, and the wool is put in at the first boiling. As cloth is more dense than wool, either spun or in the fleece, it requires one- fourth less of the salts in the boiling, and of kermes in the bath. The colour that kermes imparts to wool has much less bloom than the scarlet made with cochineal ; whence the latter has generally been preferred, since the art of heightening its colour by means of solution of tin has been known, KERMES MINERAL. See ANTI- MONY. KIFFEKILL. See MEERSCHAUM. KILLAS. The Cornish miner's name for clayslate. KI LLINITE. A mineral of a light green colour, sometimes tinged brown or yellow. Massive, or with some appearance of prisms. Structure lamellar. Lustre glimmering ; translucent ; yields to the knife ; and is easily frangible. Spec. grav. 2.698. Its constitu- ents are silica 52.49, alumina 24.50, lime, magnesia, and oxide of iron, 0.5, potash 5, oxide of iron 2.49, oxide of manganese 0-75, water 5. Dr. Barker. Before the blowpipe it becomes white, swells, and melts into a white enamel. It was discovered by Dr. Taylor in granite veins at Killiney, near Dublin. It resembles spodumene so much, that the alkali has been suspected to be lithia, and not potash. KINATE OF LIME. A salt which forms 7 per cent, of cinchona. See ACID (KiNic). KINO. A few years ago this was intro- duced into our shops and medical practice by the name of a gum; but Dr. Duncan has shown that it is an extract. It contains also a species of tannin, whence it is used as an astringent in diarrheas. KLEBSCHIEFER. Adhesive slate. KNEBELITE. A mineral of a grey co- lour, spotted with dirty white, red, or brown. Massive. Glistening. Fracture imperfectly conchoidal. Opaque, hard, brittle, and diffi- cultly frangible. Spec. grav. 3-714. Its constituents are silica 32.5, protoxide of iron 32.0, protoxide of manganese 35. Dobe- remer. KOLLYRITE. A white, massive, soft, and light mineral, which feels greasy, and adheres to the tongue. It becomes transparent in water, and falls to pieces. It consists of 14 silica, 45 alumina, and 42 water. Kla- proth. It occurs in porphyry in Hungary. KONIGrlNE. A mineral in small eme- rald, or blackish-green, translucent crystals. It resembles JBrochantite, and is probably a subsulphate of copper. M. Levy in Annals of Phil xi. 194. KONITE. See CONITE. KOUMISS. A vinous liquid, which the Tartars make by fermenting mare's milk. Something similar is prepared in Orkney and Shetland. KOUPHOLITE. A variety of prehnite found near Bareges. KRAMERIC ACID. See ACID MERIC). KUPFER NICKEL. See NICKEL. N N 2 LAB LAB LABDANUM. A resin of a species of cistus in Canclia, of a blackish colour. The country people collect it by means of a staff, at the end of which are fastened many leather thongs, which they gently strike on the trees. They form it into cylindrical pieces, which are called labdanum in tortis. It is greatly adulterated by the addition of black sand. It has been used in cephalic and stomachic plasters and perfumes. LABORATORY. A place properly fitted up for the performance of chemical operations. As chemistry is a science founded entirely on experiment, we cannot hope to understand it well, without making such experiments as verify most of the known fundamental opera- tions, and also such as reasoning, analogy, and the spirit of inquiry, never fail to suggest to those whose taste and suitable talents lead them to this essential part of experimental philosophy. Besides, when a person himself observes, and operates, he must perceive, even in the most common operations, a great variety of small facts, which must necessarily be known, but which are not mentioned either in books or in memoirs, because they are too numerous, and would appear too minute. Lastly, there are many qualities in the several agents, of which no just notion can be given by writing, and which are perfectly well known as soon as they have been once made to strike our senses. Many people think, that a laboratory level with the ground is most convenient, for the sake of water, pounding, washing, &c. It certainly has these advantages ; but it is also subject to very great inconvenience from moisture. Constant moisture, though not very con- siderable and sensible in many respects, is a very great inconvenience in a chemical labo- ratory. In such a place, most saline matters become moist in time, and the inscriptions fall off, or are effaced ; the bellows rot ; the metals rust ; the furnaces moulder, and every thing almost spoils. A laboratory, therefore, is more advantageously placed above than be- low the ground, that it may be as dry as possi- ble. The air must have free access to it ; and it must even be so constructed, that, by means of two or more opposite openings, a current of air may be admitted, to carry off any noxious vapours or dust- In the laboratory a chimney ought to be constructed, so high that a person may easily stand under it, and as extensive as is possible ; that is, from one wall to another. The fun- nel of this chimney ought to be as high as is and sufficiently contracted to make a good draught. As charcoal only is burnt under this chimney, no soot is collected in it; and therefore it need not be so wide as to allow a chimney-sweeper to pass up into it. Under this chimney may be constructed some brick furnaces, particularly a melting furnace, a furnace for distilling with an alembic, and one or two ovens like those in kitchens. The rest of the space ought to be filled up with stands of different heights, from a foot to a foot and a half, on which portable furnaces of all kinds are to be placed. These furnaces are the most convenient, from the facility of disposing them at pleasure; and they are the only furnaces which are ne- cessary in a small laboratory. A double pair of bellows of moderate size must also be placed as commodiously under the chimney, or as near, as the place will allow. These bellows are sometimes mounted in a portable frame; which is sufficiently convenient, when the bellows are not more than eighteen or twenty inches long. These bellows ought to have a pipe directed toward the hearth where the forge is to be placed. The necessarjt furnaces are, the simple fur- nace, for distilling with a copper alembic ; a lamp furnace ; two reverberatory furnaces of different sizes, for distilling with retorts ; an air or melting furnace, an assay furnace, and a forge furnace. Under the chimney, at a convenient height, must be a row of hooks driven into the back and side walls ; upon which are to be hung small shovels; iron pans; tongs; straight, crooked, and circular pincers ; pokers ; iron rods, and other utensils for disposing the fuel and managing the crucibles. To the walls of the laboratory ought to be fastened shelves of different breadths and heights ; or these shelves may be suspended by hooks. The shelves are to contain glass vessels, and the products of operations, and ought to be in as great a number as is possible. In a laboratory where many expeiiments are made, there cannot be too many shelves. The most convenient place for a stone or leaden cistern, to contain water, is a corner of the laboratory, and under it a sink ought to be placed with a pipe, by which the water poured into it may discharge itself. As the vessels are always cleaned under this cistern, cloths and bottle brushes ought to be hung upon hooks fastened in the walls near it. In the middle of the laboratory a large table is to be placed, on which mixtures are to be made, preparations for operations, so- lutions, precipitations, small filtrations ; in a word, whatever does not require fire, except- ing that of a lamp. LAB 549 LAB In convenient parts of the laboratory are to be placed blocks of wood upon mats ; one of which is to support a middle-sized iron mor- tar ;' another to support a middle-sized marble, or rather hard stone mortar ; a third to support an anvil. Near the mortars are to be hung searces of different sizes and fineness ; and near the anvil a hammer, files, rasps, small pincers, scissars, shears, and other small uten- sils, necessary to give metals a form proper for the several operations. Two moveable trestles ought to be in a la- boratory, which may serve to support a large filter mounted upon a frame, when it is re- quired. This apparatus is removed occasion- ally to the most convenient place. Charcoal is an important article in a labo- ratory, and it therefore must be placed within reach ; but as the black dust which flies about it whenever it is stirred is apt to soil every thing in the laboratory, it had better be in some place near the laboratory, together with some furze, which is very convenient for kindling fires quickly. This place serves, at the same time, for containing bulky things which are not often wanted ; such as furnaces, bricks, tiles, clay, fire-clay, quicklime, sand, and many other things necessary for chemical operations. Lastly, a middle-sized table, with solid feet, ought to be enumerated among the large moveables of a laboratory, the use of which is to support a porphyry, or levigating stone, or rather a very hard and dense grit-stone, toge- ther with a muller made of the same kind of stone. The other small moveables or utensils of a laboratory are, small hand mortars of iron, glass, agate, and Wedgewood's ware, and their pestles; earthen, stone, metal, and glass vessels of different kinds, funnels, and measures. Some white writing paper, and some un- sized paper for filters ; a large number of clean straws, eight or ten inches long, for stirring mixtures in glasses, and for supporting paper filters placed in glass funnels. Glass tubes for stirring and mixing corro- sive liquors ; spatulas of wood, ivory, metal, and glass. Thin pasteboards, and horns, very conve- nient for collecting matters bruised with water upon the levigating stone, or in mortars ; corks of all sizes ; bladders and linen strips for luting vessels. A good portable pair of bellows ; a good steel for striking fire ; a glue-pot, with its little brush ; lastly, a great many boxes, of various sizes, for containing most of the above-men- tioned things, and which are to be placed upon the shelves. Besides these things, some substances are so necessary in most chemical operations, that they may be considered as instruments requi- site for the practice of this science. These substances are called reagents, which see under ORES (ANALYSIS OF), and WATERS (MINERAL). All metals, which ought to be very pure. A person provided with such instruments and substances may at once perform many chemical experiments. The general observations of Macquer upon the conducting of chemical processes are truly valuable and judicious. Method, order, and cleanliness, are essentially necessary in a che- mical laboratory. Every vessel and utensil ought to be well cleansed as often as it is used, and put again into its place ; labels ought to be put upon all the substances. These cares, which seem to be trifling, are however very fatiguing and tedious ; but they are also very important, though frequently little observed. When a person is keenly engaged, experiments succeed each other quickly ; some seem nearly to decide the matter, and others suggest new ideas ; he cannot but proceed to them imme- diately, and he is led from one to another: he thinks he shall easily know again the pro- ducts of the first experiments, and therefore he does not take time to put them in order ; he prosecutes with eagerness the experiments which he has last thought of; and in the mean time, the vessels employed, the glasses and bottles filled, so accumulate, that he cannot any longer distinguish them ; or, at least, he is uncertain concerning many of his former products. This evil is increased, if a new series of operations succeed, and occupy all the laboratory ; or, if he be obliged to quit it for some time, every thing then goes into con- fusion. Thence it frequently happens, that he loses the fruits of much labour, and that he must throw away almost all the products of his experiments. When new researches and inquiries are made, the mixtures, results, and products of all the operations ought to be kept a long time, distinctly labelled and registered ; for these things, when kept some time, frequently pre- sent phenomena that were not at all suspected. Many fine discoveries in chemistry have been made in this manner ; and many have certain- ly been lost by throwing away too hastily, or neglecting the products. Since chemistry offers many views for the improvement of many important arts ; as it presents prospects of many useful and profit- able discoveries ; those who apply their labours in this way ought to be exceedingly circum- spect, not to De led into an useless expense of money and time. In a certain set of experi- ments, some one is generally of an imposing appearance, although in reality it is nothing more. Chemistry is full of these half suc- cesses, which serve only to deceive the unwary, to multiply the number of trials, and to lead to great expense before the fruitlessness of the search is discovered. By these reflections we do not intend to divert from' all sucji researches, LAB 550 LAB those whose taste and talents render them fit for them ; on the contrary, we acknowledge, that the improvement of the arts, and the dis- covery of new objects of manufacture and com- merce,are undoubtedly the finest and most inte- resting part of chemistry, and which make that science truly valuable ; for without these ends, what would chemistry be but a science purely theoretical, and capable of employing only some abstract and speculative minds, but use- less to society ? We acknowledge also, that the successes in this kind of chemical inquiry are not rare ; and that their authors have some- times acquired fortunes, so much the more ho- nourable, as being the fruits of their talents and industry. But we repeat, that, in these researches, the more dazzling and near any success appears, the more circumspection, and even distrust, is necessary. See ANALYSIS, ATTRACTION, BALANCE. The plates annexed, with the following explanations of them, will give the student an idea of a large variety of the most useful and necessary articles of a chemical appara- tus. Plate II. fig. I. Crucibles or pots, made either of earth, black lead, forged iron, or platina. They are used for roasting, calcina- tion, and fusion. Fig. 2. Cucurbits, matrasses, or bodies, which are glass, earthen, or metallic vessels, usually of the shape of an egg, and open at top. They serve the purposes of digestion, evaporation, &c. Fig. 3. Retorts are globular vessels of earthenware, glass, or metal, with a neck bent on one side. Some retorts have another neck or opening at their upper part, through which they may be charged, and the opening may be afterwards closed with a stopple. These are called tubulated retorts. A Welter's tube of safety may be inserted in this opening, instead of a stopple. See Plate VV. fig. 1. b and e. Receivers are vessels, usually of glass, of a spherical form, with a straight neck, into which the neck of the retort is usually inserted. When any proper substance is put into a re- tort, and heated, its volatile parts pass over into the receiver, where they are condensed. See fig. 5. and Plate IV. fig. 2. k. Fig. 4. The alembic is used for distillation, when the products are too volatile to admit of the use of the last mentioned apparatus. The alembic consists of a body a, to which is adapted a head b. The head is of a conical figure, and has its external circumference or base depress- ed lower than its neck, so that the vapours which rise, and are condensed against its sides, run down into the circular channel formed by its depressed part, from whence they are con- veyed by the nose or beak c, into the receiver d. This instrument is less simple than the retort, which certainly may be used for the most volatile products, if care be taken to ap- ply a gentle heat on such occasions. But the alembic has its conveniences. In particular, the residues of distillations may be easily cleared out of the body a ; and in experiments of su- blimation, the head is very convenient, to re- ceive the dry products, while the more volatile and elastic parts pass over into the receiver. Fig. 6. represents the large stills used in the distillation of ardent spirits, a represents the body, and 6 the head, as before. Instead of using a refrigeratory or receiver, the spirit is made to pass through a spiral pipe called the worm, which is immersed in a tub of cold water d. During its passage it is con- densed, and comes out at the lower extremity tf, of the pipe, in a fluid form. The manner in which the excise laws for Scotland were framed, rendering it advan- tageous to the distillers in that country to have stills of small capacity, which they could work very quickly, their ingenuity was excited to contrive the means of effecting this. It was obvious, that a shallow still, with a broad bottom completely exposed to a strong heat, would best answer the purpose : and this was brought to such perfection, that a still of the capacity of 40 gallons in the body, and three in the head, charged with 1 6 gallons of wash, could be worked 480 times in 24 hours. Fig. 7- is a vertical section of this still. #, the bottom, joined to &, the shoulder, with solder, or rivets, or screws and lute, c, the turned- up edge of the bottom, against which, and on a level with a, the brick-work of the coping of the flue rests, preventing the flame from getting up to touch c. d, the discharge pipe. c e, the body of the still. /, section of the central steam escape pipe, g, section of one of the lateral steam escape pipes ; ft, outside view of another, i i i i, inferior apertures of lateral steam pipes ; k k k A 1 , their superior apertures. 1 1, bottom scraper, or agitator, which may either be made to apply close to the bottom, or to drag chains : m, the upright shaft of this engine, as it is called ; , the ho- rizontal wheel with its supporters, o, its ver- tical wheel, p, its handle and shaft ; w, sup- port of the shaft- r, froth and ebullition jet- breaker, resting on the cross bar s. f, its up- right shaft, w, its cup-mouthed collar, filled with wool and grease, and held down by a plate and screws. r>, general steam escape pipe, or head. The charge pipe, and the sight hole, for the man who charges it to see when it is sufficiently full, are not seen in this view. The best construction of a furnace has not been well ascertained from experience. There are facts which show, that a fire made on a grate near the bottom of a chimney, of equal width throughout, and open both above and below, will produce a more intense heat than any other furnace. What may be the limits for the height of the chimney is not ascertained from any precise trials ; but thirty times its diameter would not probably be too high. It LAB 551 LAB seems to be an advantage to contract the dia- meter of a chimney, so as to make it smaller than that of the tire- place, when no other air is to go up the chimney than what has passed through the fire ; and there is no prospect of advantage to be derived from widening it. Plate IV. fig. 3. exhibits the wind or air furnace for melting, a is the ash-hole, /an opening for the air. c is the fire-place, con- taining a covered crucible, standing on a sup- port of baked earth, which rests on the grate ; d is the passage into e, the chimney. At d a shallow crucible or cupel may be placed in the current of the flame, and at x is an earthen or stone cover, to be occasionally taken off for the purpose of supplying the fire with fuel. Fig. 2. is a reverberatory furnace, a a, the ash-pit and fire-place. b 6, body of the fur- nace, c c, dome, or reverberating roof of the furnace, d d, chimney, e e^ door of the ash- pit. //, door of the fire-place, g g, handles of the body. A, aperture to admit the head of the retort, i i, handles of the dome. A-, re- ceiver. / J, stand of the receiver, m m, retort, represented in the body by dotted lines. Another reverberatory furnace, a little dif- fering in figure, may be seen in Plate I. fig. 2. a. M. Chenevix has constructed a wind fur- nace, which is in some respects to be preferred to the usual form. The sides, instead of being perpendicular, are inverted, so that the hollow space is pyramidical. At the bottom the opening is 13 inches square, and at the top but eight The perpendicular height is 17 inches. This form appears to unite the fol- lowing advantages: 1st, A great surface is exposed to the air, which, having an easy entrance, rushes through the fuel with great rapidity ; 2d, The inclined sides act in some measure as reverberating surfaces; and 3d, The fuel falls of itself, and is always in close contact with the crucible placed near the grate. The late Dr. Kennedy of Edinburgh, whose opinion on this subject claims the greatest weight, found that the strongest heat in our common wind furnaces was within two or three inches of the grate. This, therefore, is the most advantageous position for the crucible, and still more so when we can keep it sur- rounded with fuel. It is inconvenient and dangerous for the crucible, to stir the fire often to make the fuel fall, and the pyramidical form renders this unnecessary. It is also more easy to avoid a sudden bend in the chimney, by the upper part of the furnace advancing as in this construction. In Plate IV. fig. 1 . a is a grate ; c and c are two bricks, which can be let in at pleasure to diminish the capacity ; b is another grate, which can be placed upon the bricks c and c for smaller purposes ; d and d are bricks which can be placed upon the grate b to diminish the upper capacity, so that, in fact, there are four different size* in the same furnace. The bricks should all be ground down to the slope of the furnace, and fit in with tolerable accuracy. They are totally inde- pendent of the pyramidical form of the fur- nace. Mr. Aikin's portable blast furnace is com, posed of three parts, all made out of the com- mon thin black lead melting-pots, sold in London for the use of the goldsmith. The lower piece c, fig. 6. is the bottom of one of these pots, cut off so low as only to leave a cavity of about an inch deep, and ground smooth above and below. The outside dia- meter, over the top, is five inches and a half. The middle piece or fire-place a, is a larger portion of a similar pot, with a cavity about six inches deep, and measuring seven inches and a half over the top, outside diameter, and perforated with six blast holes at the bottom. These two pots are all that are essentially neces- sary to the furnace for most operations ; but when it is wished to heap up fuel above the top of a crucible contained, and especially to protect the eyes from the intolerable glare of the fire when in full height, an upper pot b is added, of the same dimensions as the middle one, and with a large opening in the side, cut to allow the exit of the smoke and flame. It has also an iron stem, with a wooden handle (an old chisel answers the purpose very well) for removing it occasionally. The bellows, which are double (d), are firmly fixed, by a little contrivance which will take off and on, to a heavy stool, as represented in the plate ; and their handle should be lengthened so as to make them work easier to the hand. To in- crease their force, on particular occasions, a plate of lead may be firmly tied on the wood of the upper flap. The nozzle is received into a hole in the pot c, which conducts the blast into its cavity. Hence the air passes into the fire-place a, through six holts of the size of a large gimlet, drilled at equal distances through the bottom of the pot, and all converging in an inward direction, so that if prolonged, they would meet about the centre of the upper part of the fire. No luting is necessary in using this furnace, so that it may be set up and taken down immediately. Coak, or com- mon cinders, taken from the fire when the coal ceases to blaze, sifted from the dust, and broken into very small pieces, forms the best fuel for higher heats. The fire may be kindled at first by a few lighted cinders, and a small quantity of wood charcoal. The heat which this little furnace will afford is so intense, that its power was at first discovered acci- dentally by the fusion of a thick piece of cast iron. The utmost heat procured by it was 167 of Wedgewood's pyrometer, when a Hes- sian crucible was actually sinking down in a state of porcelaneous fusion. A steady heat of 155 or 160 may be depended on, if the fire be properly managed, and the bellows worked with vigour. LAB 552 LAB The process of cupellation may be exhibited in a lecture, or performed at other times, by means of this furnace. The method consists in causing a portion of the blast to be diverted from the fuel, and to pass through a crucible in which the cupel is placed. This arrange- ment supplies air ; and the whole may be seen by a sloping tube run through the cover of the crucible. Charcoal is the material most commonly used in furnaces. It produces an intense heat without smoke, but it is consumed very fast. Coak or charred pit-coal produces a very strong and lasting heat. Neither of these produces a strong heat at a distance from the fire. Where the action of flame is required, wood or coal must be burned. Several inconveniencies attend the use of coal, as its fuliginous fumes, and its aptitude to stop the passage of air by becoming fused. It is used, however, in the reverbera- tory furnaces of glass-houses, and is the best material where vessels are to be supplied with a great quantity of heat at no great intensity, such as in distilleries, &c. Frequently, however, the flame of an Ar- gand lamp mayjbe employed very conveniently for chemical purposes. PI. III. fig. 2. is a representation of a lamp furnace, as it is per- haps not very properly called, as improved by Mr. Accum. It consists of a brass rod screwed to a foot of the same metal, loaded with lead. On this rod, which may be unscrewed in the middle for rendering it more portable, slide three brass sockets with straight arms, termi- nating in brass rings of different diameters. The largest measures four inches and a half. These rings serve for supporting glass alembics, retorts, Florence flasks, evaporating basins, gas bottles, &c. ; for performing distillations, di- gestions, solutions, evaporations, saline fusions, concentrations, analyses with the pneumatic apparatus, &c. If the vessels require not to be exposed to the naked fire, a copper sand bath may be interposed, which is to be previously placed in the ring. By means of a thumb- screw acting on the rod of the lamp, each of the brass rings may be set at different heights, or turned aside, according to the pleasure of the operator. Below these rings is a fountain- lamp on Argand's plan, having a metallic valve within, to prevent the oil from running out while the reservoir is put into its place. This lamp also slides on the main brass rod by means of a socket and thumb-screw. It is therefore easy to bring it nearer, or to move it further, at pleasure, from the vessel, which may remain fixed ; a circumstance which, inde- pendent of the elevation and depression of the wicks of the lamp, affords the advantage of heating the vessels by degrees after they are duly placed, as well as of augmenting or di- minishing the heat instantly ; or for maintain- ing it for several hours at a certain degree, without in the least disturbing the apparatus suspended over it. It may therefore be used for producing the very gentle heat necessary for the rectification of ethers, or the strong heat requisite for distilling mercury. The chief improvement of this lamp consists in its power of affording an intense heat by the ad- dition of a second cylinder, added to that of the common lamp of Argand. This additional cylinder encloses a wick of one inch and a half in diameter, and it is by this ingenious con- trivance, which was first suggested by Mr. Webster, that a double flame is caused, and more than three times the heat of an Argand's lamp of the largest size is produced. Every effect of the most violent heat of fur- naces may be produced by the flame of a candle or lamp, urged upon a small particle of any substance, by the blowpipe. This in- strument is sold by the ironmongers, and con- sists merely of a brass pipe about one eighth of an inch diameter at one end, and the other tapering to a much less size, with a very small perforation for the wind to escape. The smaller end is bent on one side. For philoso- phical or other nice purposes the blowpipe is provided with a bowl or enlargement, a (PI. IV. fig. 5.), in which the vapours of the breath are condensed and detained, and also with three or four small nozzles, J, with different aper- tures, to be slipped on the smaller extremity. These are of use when larger or smaller flames are to be occasionally used, because a larger flame requires a large aperture, in order that the air may effectually urge it upon the matter under examination. There is an artifice in the blowing through this pipe, which is more difficult to describe than to acquire. The effect intended to be produced is a continual stream of air for many minutes, if necessary, without ceasing. This is done by applying the tongue to the roof of the mouth, so as to interrupt the communica- tion between the mouth and the passage of the nostrils ; by which means the operator is at liberty to breathe through the nostrils, at the same time that by the muscles of the lips he forces a continual stream of air from the anterior part of the mouth through the blow- pipe. When the mouth begins to be empty, it is replenished by the lungs in an instant, while the tongue is withdrawn rrom the roof of the mouth, and replaced again in the same manner as in pronouncing the monosyllable tut. In this way the stream may be continued for a long time without any fatigue, if the flame be not urged too impetuously, and even in this case no other fatigue is felt than that of the muscles of the lips. A wax candle, of a moderate size, but thicker wick than they are usually made with, is the most convenient for occasional experi- ments ; but a tallow candle will do very well. The candle should be snuffed rather short, and the wick turned on one side toward the object, so that a part of it should lie horizontally. The stream of air must be blown along this LAB 553 LAB horizontal part, as near as may be without striking the wick. If the flame be ragged and irregular, it is a proof that the hole is not round and smooth ; and if the flame have a cavity through it, the aperture of the pipe is too large. When the hole is of a proper figure, and duly proportioned, the flame con- sists of a neat luminous blue cone, surrounded by another flame of a more faint and indistinct appearance. The strongest heat is at the point of the inner flame. The body intended to be acted on by the blowpipe ought not to exceed the size of a peppercorn. It may be laid upon a piece of close-grained, well-burned charcoal; unless it be of such a nature as to sink into the pores of this substance, or to have its properties affected by its inflammable quality. Such bodies may be placed in a small spoon made of pure gold, or silver, or platina. Many advantages may be derived from the use of this simple and valuable instrument. Its smallness, which renders it suitable to the pocket, is no inconsiderable recommendation. The most expensive materials, and the mi- nutest specimens of bodies, may be used in these experiments ; and the whole process, instead of being carried on in an opaque vessel, is under the eye of the observer from beginning to end. It is true that very little can be de- termined in this way concerning the quantities of product ; but, in most cases, a knowledge of the contents of any substance is a great acquisition., which is thus obtained in a very short time, and will, at all events, serve to fchow the best and least expensive way of con- ducting processes with the same matters in the larger way. The blowpipe has deservedly of late years been considered as an essential instrument in a chemical laboratory ; and several attempts have been made to facilitate its use by the addition of bellows, or some other equivalent instruments. These are doubtless very con- venient, though they render it less portable formineralogical researches. I twill not, here, be necessary to enter into any description of a pair of double bellows fixed under a table, and communicating with a blowpipe which passes through the table. Smaller bellows, of a portable size for the pocket, have been made for the same purpose. The ingenious chemist will find no great difficulty in adapting a blad- der to the blowpipe, which, under the pressure of a board, may produce a constant stream of air, and may be replenished, as it becomes empty, by blowing into it with bellows, or the mouth, at another aperture furnished with a valve opening inwards. The chief advantage these contrivances have over the common blowpipe is, that they may be filled with oxygen gas, which increases the activity of combustion to an astonishing de- gree. The vapour from alcohol has likewise been employed, and an ingenious contrivance for this purpose by Mr. Hooke is repre- sented, PI. IV. fig. 4. a is a hollow sphere for containing alcohol, resting upon a shoulder in the ring o. If the bottom be made flat instead of spherical, the action of the flame will then be greater. 6 is a bent tube with a jet at the end, to convey the alcohol in the state of vapour into the flame at q ; this tube is con- tinued in the inside up to c, which admits of a being filled nearly, without any alcohol run- ning over, d is a safety valve, the pressure of which is determined at pleasure, by screwing higher or lower on the pillar e the two milled nuts/ and , carrying the steel arm/*, which rests on the valve, i is an opening for putting in the alcohol, k is the lamp, which adjusts to different distances from , by sliding up or down the two pillars II. The distance of the flame q from the jet is regulated by the pipe which holds the wick being a little removed from the centre of the brass piece m, and of course revolving in a circle, n the mahogany stand. For the various habitudes of bodies when examined by the blowpipe, see BLOWPIPE. Little need be said concerning the manner of making experiments with fluid bodies in the common temperature of the atmosphere. Basins, cups, phials, matrasses, and other similar vessels, form the whole apparatus required for the purpose of containing the matters intended to be put together ; and no other precaution or instruction is required, than to use a vessel of such materials as shall not be corroded or acted upon by its contents, and of sufficient capacity to admit of any sud- den expansion or frothing of the fluid, if expected. This vessel must be placed in a current of air, if noxious fumes arise, in order that these may be blown from the operator. The method of making experiments with permanently elastic fluids, or gases, though simple, is not so obvious. We live immersed in an atmosphere not greatly differing in den- sity from these fluids, which for this reason are not sufficiently ponderous to be detained in open vessels by their weight. Their remark- able levity, however, affords a method of con- fining them by means of other denser fluids. Dr. Priestley, whose labours so far exceeded those of his predecessors and contemporaries, both in extent and importance, that he may with justice be styled the father of this im- portant branch of natural philosophy, used the following apparatus. PI. III. fig. I. a represents a wooden ves- sel or tub ; k k k, is a shelf fixed in the tub. When this apparatus is used, the tub is to be filled with water to such a height, as to rise about one inch above the upper surface of the shelf. 6, g, /, are glass jars inverted with their mouths downward, which rest upon the shelf. If these, or any other vessels, open only LAB 554 LAB at one end, be plunged under the water, and inverted after they are filled, they will remain full, notwithstanding their being raised out of the water, provided their mouths be kept im- mersed ; for in this case the water is sustained by the pressure of the atmosphere, in the same manner as the mercury in the barometer. It may, without difficulty, be imagined, that if common air, or any other fluid resembling common air in lightness and elasticity, be suf- fered to enter these vessels, it will rise to the upper part, and the surface of the water will subside. If a bottle, a cup, or any other vessel, in that state which is usually called empty, though really full of air, be plunged into the water with its mouth downwards, scarce any water will enter, because its en- trance is opposed by the elasticity of the in- cluded air ; but if the vessel be turned up, it immediately fills, and the air rises in one or more bubbles to the surface. Suppose this operation to be performed under one of the jars which are filled with water, the air will ascend as before ; but instead of escaping, it will be detained in the upper part of the jar. In this manner, therefore, we see, that air may be emptied out of one vessel into another by an inverted pouring, in which the air is made to ascend from the lower vessel i to the upper g-, in which the experiments are per- formed, by the action of the weightier fluid, exactly similar to the common pouring of denser fluids detained in the bottoms of open vessels, by the simple action of gravity. When the receiving vessel has a narrow neck, the air may be poured through a glass funnel h. c (Ibid.) is a glass body or bottle, the bot- tom of which is blown very thin, that it may support the heat of a candle suddenly applied, without cracking. In its neck is fitted, by grinding, a tube d, curved neatly in the form of the letter s. This kind of vessel is very useful in various chemical operations, for which it will be convenient to have them of several sizes. In the figure, the body c is represented as containing a fluid, in the act of combining with a substance that gives out air, which passes through the tube into the jar i, under the mouth of which the other extremity of the tube is placed. At e is a small retort of glass or earthen ware, the neck of which being plunged in the water, beneath the jar f, is supposed to emit the elastic fluid, extricated from the contents of the retort, which is received in the jar. When any thing, as a gallipot, is to be supported at a considerable height within a jar, it is convenient to have such wire-stands as are represented fig. 3. These answer bet- ter than any other, because they take up but little room, and are easily bent to any figure or height. In order to expel air from solid substances by means of heat, a gun-barrel, with the touch-hole screwed up and rivetted, may be used instead of an iron retort. The subject may be placed in the chamber of the barrel, and the rest of the bore may be filled with dry sand, that has been well burned, to expel whatever air it might have contained. The stem of a tobacco-pipe, or a small glass tube, being luted in the orifice of the barrel, the other extremity must be put into the fire, that the heat may expel the air from its contents. This air will of course pass through the tube, and may be received under an inverted vessel, in the usual manner. But the most accurate method of procuring air from several substances, by means of heat, is to put them, if they will bear it, into phials full of quicksilver, with the mouths inverted in the same, and then throw the focus of a burning lens or mirror upon them. For this purpose, their bottoms should be round and very thin, that they may not be liable to fly with the sudden application of heat. The body c, PI. III. fig. 1. answers this purpose very well. Many kinds of air combine with water, and therefore require to be treated in an apparatus in which quicksilver is made use of. This fluid being very ponderous and of con- siderable price, it is an object of convenience, as well as economy, that the trough and vessels should be smaller than when water is used. See PL VV. fig. I.// When trial is to be made of any kind of air, whether it be fit for maintaining com- bustion, the air may be put into along narrow glass vessel, the mouth of which, being care- fully covered, may be turned upward. A bit of wax candle being then fastened to the end of a wire, which is bent so that the flame of the candle may be uppermost, is to be let down into the vessel, which must be kept covered till the instant of plunging the lighted candle into the air. Where the change of dimensions, which follows from the mixture of several kinds of air, is to be ascertained, a graduated narrow cylindrical vessel may be made use of. . The gradations may be made by pouring in suc- cessive equal measures of water into this vessel, and marking its surface at each addition. The measure may be afterward used for the dif- ferent kinds of air, and the change of dimen- sions will be shown by the rise or fall of the mercury or water in the graduated vessel. The purity of common air being determinable by the diminution produced by the addition of nitric oxide gas, these tubes have been called eudiometer tubes. Some substances, more especially powders, cannot conveniently be put into a phial, or passed through a fluid. When air is to be extricated from, or added to these, there is no better method, than to place them On a stand under the receiver of the air-pump, and ex- LAB 555 LAB haust the common air, instead of excluding terials are put into the lower vessel ; the middle it by water or mercury. This process re- vessel is filled with pure water, and put into quires a good air-pump, and careful manage- its place ; and the upper vessel is stopped, ment, "otherwise the common air will not be and likewise put in its place. The consequence well excluded. is, that the carbonic acid gas, passing through It is frequently an interesting object, to the valve at A, ascends into the upper part of pass the electric spark through different kinds the middle vessel, &, where, by its elasticity, of air, either alone or mixed together. In this case a metallic wire may be fastened in the upper end of a tube, and the sparks or it reacts on the water, and forces part up the tube into the vessel a ; part of the common air, in this last, being compressed, and the shock may be passed through this wire to the rest escaping by the stopper, which is made mercury or water used to confine the air. If there be reason to apprehend, that an expansion in the air may remove the mercury or water beyond the striking distance, another wire may be thrust up to receive the electricity ; or two wires may be cemented into opposite holes in the sides of an hermetically sealed tube. Holes may be made in glass, for this and other chemical uses, by a drill of copper or soft iron, with emery and water ; and where this instrument is wanting, a small round file with water will cut a notch in small vessels, such as phials or tubes, though with some danger of breaking them. In some electrical of a conical figure, that it may be easily raised. As more carbonic acid is extricated, more water rises, till at length the water in the middle vessel falls below the lower orifice of the tube. The gas then passes through the tube into the upper Vessel, and expels more of the common air by raising the stopper. In this situation the water in both vessels being in contact with a body of carbonic acid gas, it becomes strongly impregnated with this gas, after a certain time. This effect may be hastened by taking off the middle and upper vessels together, and agitating them. The valve is the most defective part of this experiments of the kind here mentioned, there apparatus ; for the capillary tube does not is reason to expect a fallacious result from the - i ,1- wires being burned by the explosion or spark. For this reason, the electricity may be made to pass through the legs of a syphon, contain- ing the air which is under consideration in the upper part of its curvature. One of the vessels, in which the legs of the syphon rest, must therefore be insulated ; and if any watery fluid be used to confine the air, it is generally sup- posed that ho combustion takes place. It is sometimes desirable to impregnate water for medicinal purposes with some gas, as the carbonic acid, and for this the appa- ratus of Dr. Nooth is very effectual and con- venient. It consists of three glass vessels, PI. III. fig. 4. The lower vessel c contains the effervescent materials ; it has a small ori- fice at d, stopped with a ground stopper, at which an additional supply of either acid, or water, or chalk, may be occasionally intro- duced. The middle vessel b is open, both above and below. Its inferior neck is fitted, by grinding, into the neck h of the lower vessel. In the former is a glass valve, formed by two pieces of tube, and a plano-convex lens, which is moveable, between them, as re- presented in fig. 5. This valve opens upwards, and suffers the air to pass ; but the water cannot return through the tubes, partly be- cause the orifice is capillary, and partly be- cause the fiat side of the lens covers the hole. The middle vessel is furnished with a cock e, to draw off its contents. The upper vessel a is fitted, by grinding, into the upper neck of the middle vessel. Its inferior part consists of a tube that passes almost as low as the centre of the middle vessel. Its upper orifice is closed by a ground stopper f. When this apparatus is to be used, the effervescent ma- admit the air through, unless there is a con- siderable quantity condensed in the lower vessel ; and the condensation has in some in- stances burst the vessel. Modern discoveries respecting bodies in the aeriform state have produced several ca- pital improvements in the vessels used for distillation. It was common with the earliest chemists, to make a small hole in the upper part of their retorts, that the elastic vapours might escape, which would otherwise have burst the vessels. By this means they lost a very considerable part of their products. Sometimes, too, it is requisite to obtain sepa- rately the condensable fluid that comes over, and the gases that are, and are not soluble in water. For this purpose a series of receivers, more or less in number as the case may re- quire, is generally employed, as in PI. W. rig. 1. which represents what is called Woolfe's apparatus, though in fact its original inventor was Glauber, with some subsequent improve- ments. The vapour that issues from the re- tort being condensed in the receiver a, the gas passes on through a bent tube into the bottle c, which is half filled with water. The gas not absorbed by this water passes through a similar bent tube to d, and so on to more, if it be thought necessary ; while the gas that is not absorbable by water, or condensable, at its exit from the last bottle is conveyed by a recurved tube into a jar g, standing in a mercurial trough// It often happens in chemical processes, from the irregularity of the heat, or other circumstances, that the condensation is more rapid in proportion to the supply of vapour at some period of the same operation than hi others ; which would endanger the fluid's being LAB 556 LAB forced backward, by the pressure of the at- mosphere, into the receiver, or even into the retort. To prevent this, Mr. Woolfe's bottles had a central neck, beside the two here de- lineated, for the insertion of a tube of safety, the lower extremity of which opened under- neath the water, and the upper communicated with the atmosphere, so as to supply air in case of sudden absorption. See Plate VV. fig. 3. h. Instead of this, however, a curved Welter's tube is now generally used, as more convenient Into this tube water is poured, till the ball 6, or *, fig. 1. is half full : when absorption takes place, the waier rises in the ball till none remains in the tube, and then the air rushes in : on the other hand, no gas~ can escape, as it has to overcome the pressure of a high column of water in the perpendicular tube. Another contrivance to prevent retrograde pressure is that of Mr. Pepys. This consists in placing over the first receiver a glass vessel, the neck of which is ground into it, and fur- nished with a glass valve, similar to that in Nooth's apparatus, so that whenever sudden condensation takes place in the receiver, its effect is merely to occasion a vacuum there. An ingenious modification of Woolfe's ap- paratus is that of Mr. Knight, PL III. fig. 6, a a a represent three vessels, each ground into the mouth of that below it. I b 6, glass tubes, the middles of which are ground into the neck of their respective vessels, the upper extremity standing above the surface of the liquor in the vessel, and the lower extremity reaching nearly to the bottom of the vessel beneath, e, a Welter's tube to prevent absorption, f, an adapter ground to fit the receiver ; to which any retort may be joined and luted before it is put into its place, c, a tube for conveying the gas into a pneumatic trough. The foot of the lowest vessel, d, slides in between two grooves in a square wooden foot, to secure the apparatus from oversetting. A stopple fitted to the upper vessel, instead of the adapter j^ converts it into a Nooth's apparatus, the ma- terials being put into the vessel a ; and in this case it has the advantage of not having a valve liable to be out of order. A very simple and commodious form of a Woolfe's apparatus is given by the late Dr. W. Hamilton, at the end of his translation of Berthollet on dyeing ; see PI. VV. fig. 3. a is the retort, the neck of which is ground into and passed through the thick collar 6, repre- sented separately at 6, with its ground stopple 0, which may be put in when the neck of the retort is withdrawn. The collar 6 is ground into the wide neck of the receiver c, the narrow neck of which is ground into the wide neck of d. d, e, /, and g, are connected in a similar manner ; and into the small necks of rf, ' 100-00 This powder was analysed, by acting on a given weight of it with dilute muriatic acid, in a pear-shaped glass vessel. Care was taken to remove the whole disengaged chlorine, without letting any liquid escape. The lime was converted into carbonate, by a solution of carbonate of ammonia. The following are the results of two independent analytical ex- periments : 1st Experiment. 2d Experiment. Chlorine evolved, 40-60 39-40 Lime, 42-27 42-22 Water, 17-13 18-38 100-00 100-00 I have reason to believe the second experi- ment the more correct of the two, and if the synthetic result be compared with it, we are led to infer that the very great body of undried chlorine passed over the lime had deposited two per cent, of water. By other experiments I satisfied myself, that dilute muriatic acid expelled nothing but pure chlorine; for the whole gas disengaged is absorbed on agitation with mercury. It does not appear possible to reconcile the above chlorides to a definite atomic constitution. The following experiments were made with much care last spring : 200 grains of the atomic protohydrate of pure lime were put into a glass globe, which was kept cool by immersion in a body of water at 50. A stream of chlorine, after being washed in water of the same temperature in another glass globe, connected to the former by a long narrow glass tube, was passed over the calcareous hydrate. The globe with the lime was detached from the rest of the appa- ratus from time to time, that the process might be suspended as soon as the augmentation of weight ceased. This happened when the 200 grains of hydrate, containing 151.9 of lime, had absorbed 1 30 grains of chlorine. By one analytical experiment it was found, that di- lute muriatic acid expelled from 50 grains of the chloride 20 grains of chlorine, or 40 per cent. ; and by another, from 40 grains 16-25 of gas, which is 40-6 per cent. From the residuum of the first, 39.7 grains of carbonate of lime were obtained by carbonate of am- monia; from that of the second, 36-6 of ig- nited muriate of lime. The whole results are therefore as follows : Synthesis. 1st Analys. 2d Analys. Mean. Chlorine, 39-39 40-00 40-62 40-3J Lime, 46-00 44-74 46-07 45-40 Water, 14-60 15-26 13-31 14-28 100-00 100-00 100-00 100-00 Though the heat generated by the action of the dilute acid has carried off in the analytical experiments a small portion of moisture with the chlorine, yet their accordance with the synthetic experiment is sufficiently good to confirm the general results. The above powder appears to have been a pure chloride, without any mixture of muriate. But it exhibits no atomic constitution in its proportions. To 200 grains of that hydrate of lime, 30 grains of water being added, the powder was subjected to a stream of chlorine in the above way, till saturation took place. Its increase of weight was 150 grains. It ought to be remarked, that in this and the preceding ex- periment there was no appreciable pneumatic pressure employed, to aid the condensation of the chlorine. In the last case, we see that the addition of 30 grains of water has enabled the lime to absorb 20 grains more of chlorine, being altogether a quantity of gas nearly equal to that of the dry lime. Thus an atom of lime seems associated with 7-9ths of an atom of chlorine. Analysis by muriatic acid confirmed this composition. It gave, Chlorine, 39-5 =51.8 cubic inches. Lime, 39-9 Water 20-6 100.0 I next exposed some of this powder to heat in a small glass retort, connected with the hydro-pneumatic trough. Gas was very co- piously disengaged, at a temperature far below ignition, the first portions coming off at the heat of boiling water ; 100 measures of the collected gas being agitated with water at 50 F., 63 measures were absorbed, and the re- maining 37 measures were oxygen, nearly pure. The smell of the first evolved gas was that of chlorine, after which the odour of LIM 576 LIM euchlorine was perceived, and latterly the smell nearly ceased, as the product became oxygen. Having thus ascertained the general products, I now subjected to the same treatment 100 grains of the same powder (that last described), in a suitable apparatus ; 30 cubic inches of gas were obtained from it, in a series of glass cylinders, standing over water at 50. The first received portion was chlorine, nearly pure, but towards the end, when the heat approached or was at ignition, oxygen became the chief product. The residuary solid matter yielded to water a solution of muriate of lime, con- taining 30 grains of the dry salt, equivalent to about 15 of lime. But the chloride, both by synthesis and analysis, seemed to contain in 100 grains 51.8 cubic inches of chlorine, (corresponding to 25.9 of oxygen), with 39.9 of lime. Thus the volume of the evolved gas proves, independent of other considerations, that a considerable portion of chlorine came off, without dislodging the oxygen from the calcium; and as in subsequent experiments this volume was found to vary with the strength of the powder, and the mode of heating it, this method of analysis becomes altogether nugatory and delusive. The truth of this conclusion will still further appear on reflect- ing, that an uncertain portion of chlorine is condensed in the water of the trough, and that most probably a little euchlorine is formed at the period when the gaseous product passes from chlorine to oxygen. Thus, of the 39-9 grains of lime present in the chloride, 24.9 seem to have merely parted with their chlo- rine, while the other 15 lost their oxygen, equivalent to 12| cubic inches, or 4-3 grains, and the remaining 10-7 of calcium combined with 19-3 of chlorine, to constitute the 30 grains of ignited muriate of lime. But 19-3 grains of chlorine form 25-3 cubic inches ; hence 51-8 25-3 = 26-5 is the volume of chlorine disengaged by the heat, to which, if we add 12 cubic inches of oxygen, the sum 39-16 is the bulk of gas that should have been received. The deficiency of 9- 1 6 cubic inches is to be ascribed to absorption of chlorine (and perhaps of euchlorine), by the water of the pueumatic trough. In the above case, about one-half of the total chlorine came off in gas, and the other half combined with the basis of the lime, to the exclusion of its oxygen. I have observed, that the proportion of chlorine to that of oxygen given off by heat, increases, as one may naturally imagine, with the strength of the bleaching powder. When it is very weakly impregnated with chlorine, as is the case with some commercial samples, then the evolved gas consists in a great measure of oxygen. Of the Manufacture of Bleaching Powder. A great variety of apparatus has been at different times contrived for favouring the combination of chlorine with slacked lime, for the purposes of commerce. One of the most ingenious forms was that of a cylinder, or barrel, furnished with narrow wooden shelves within, and suspended on a hollow axis, by which the chlorine was admitted, and round which the barrel was made to revolve. By this mode of agitation, the lime-dust being exposed on the most extensive surface, was speedily impregnated with the gas to the re- quisite degree. Such a mechanism I saw at MM. Oberkamf and Widmer's celebrated falrique de toiles peintes, at JoUy, in 1816. But this is a costly refinement, inadmissible on the largest scale of British manufacture. The simplest, and in my opinion the best, construction for subjecting lime powder to chlorine, is a large chamber eight or nine feet high, built of siliceous sandstone, having the joints of the masonry secured with a cement composed of pitch, rosin, and dry gypsum in equal parts. A door is fitted into it at one end, which can be made air-tight by stripes of cloth and clay lute. A window in each side enables the operator to judge how the impregnation goes on by the colour of the air, and also gives light for making the arrange- ments within at the commencement of the process. As water-lutes are incomparably superior to all others, where the pneumatic pressure is small, I would recommend a large valve, or door, on this principle, to be made in the roof, and two tunnels of considerable width atthebottom of each side wall. The threecovers could be simultaneously lifted off by cords passing over a pulley, without the necessity of the workmen approaching the deleterious gas, when the apartment is to be opened. A great number of wooden shelves, or rather trays, eight or ten feet long, two feet broad, and one inch deep, are provided to receive the sifted slacked lime, containing generally about two atoms of lime to 3 of water. These shelves are piled one over another in the chamber, to the height of five or six feet, cross-bars below each keeping them about an inch asunder, that the gas may have free room to circulate over the surface of the calcareous hydrate. The alembics for generating the chlorine, which are usually nearly spherical, are in some cases made entirely of lead, in others, of two hemispheres joined together in the middle, the upper hemisphere being lead, the under one cast-iron. The first kind of alembic is enclosed for two-thirds from its bottom in a leaden or iron case, the interval of two inches between the two being destined to receive steam from an adjoining boiler. Those which consist below of cast-iron have their bottom directly exposed to a very gentle fire ; round the outer edge of the iron hemi- sphere a groove is cast, into which the under edge of the leaden hemisphere fits, the joint LIM 577 LIM being rendered air-tight by Roman or patent cement*. In this leaden dome there are four apertures, each secured by a water-lute. The first opening is about ten or twelve inches square, and is shut with a leaden valve, with incurvatcd edges, that fit in the water-channel at the margin of the hole. It is destined for the admission of a workman to rectify any derangement in the apparatus of rotation, or to detach hard concretions of salt from the bottom. The second aperture is in the centre of the top. Here a tube of lead is fixed, which descends nearly to the bottom, and down through which the vertical axis passes, to whose lower end the cross bars of iron or of wood, sheathed with lead, are attached, by whose revolution the materials receive the proper agitation for mixing the dense man- ganese with the sulphuric acid and salt. The motion is communicated either by the hand of a workman applied from time to time to a winch at top, or it is given by connecting the axis with wheel work, impelled by a stream of water, or a steam-engine. The third open- ing admits the syphon-tbrmed funnel, through which the sulphuric acid is introduced and the fourth is the orifice of the eduction pipe. Manufacturers differ much from each other in the proportion of their materials for gene- rating chlorine. In general, 10 cwt. of salt are mixed with from 10 to 14 cwt. of man- ganese ; to which mixture, after its introduc- tion into the alembic, from 12 to 14 of sul- phuric acid are added in successive portions. That quantity of oil of vitriol must, however, be previously diluted with water, till its spe- cific gravity becomes about 1-65. But, indeed, this dilution is seldom actually made, for the manufacturer of bleaching powder almost al- ways prepares his own sulphuric acid for the purpose, and therefore carries its concentration no higher in the leaden boilers than the density of 1-65, which, from my table cf sulphuric acid, indicates l-4th of its weight of water, and therefore l-3d more of such acid must be used. The fourth aperture, I have said, admits the eduction pipe. This pipe is afterwards con- veyed into a leaden chest, or cylinder, in which all the other eduction pipes also ter- minate. -They are connected with it simply by water-lutes, having a hydrostatic pressure of 2 or 3 inches. In this general divcrsorium the chlorine is washed from adhering muriatic acid, by passing through a little water, in which each tube is immersed, and from this the gas is led offby a pretty large leaden tube, into the combination room. It usually enters * A mixture of lime, clay, and oxide of iron, separately calcined, and reduced to a fine powder. It must be kept in close vessels, and mixed with the requisite water when used. in the top of the ceiling, whence it diffuses its heavy gas equally around. Four days are required, at the ordinary rate of working, for making good marketable bleaching powder. A more rapid formation would merely endanger an elevation of tem- perature, productive of muriate of lime, at the expense of the bleaching quality. But skilful manufacturers use here an alternating process. They pile up, first of all, the wooden trays only in alternate shelves in each column. At the end of two days the distillation is inter, mitted, and the chamber is laid open. After two hours the workman enters, to introduce the alternate trays covered with fresh hydrate of lime, and at the same time rakes up tho- roughly the half-formed chloride in the others. The door is then secured, and the chamber, after being filled for two days more with chlorine, is again opened, to allow the first set of trays to be removed, and to be replaced by others containing fresh hydrate, as before. Thus the process is conducted in regular alternation; thus, to my knowledge, very superior bleaching powder is manufactured, and thus the chlorine may be suffered to enter in a pretty uniform stream. But for this judicious plan, as the hydrate advances in impregnation, its faculty of absorption be- coming diminished, it would be requisite to diminish proportionately the evolution of chlo- rine, or to allow the excess to escape, to the great loss of the proprietor, and, what is of more consequence, to the great detriment of the health, of the workmen. The manufacturer generally reckons on obtaining from one ton of rock-salt, employed as above, a ton and a half of good bleaching powder. But the following analysis of the operation will show, that he ought to obtain two tons. Science has done only half her duty, when she describes the best apparatus and manipu- lations of a process. The maximum produce should be also demonstrated, in order to show the manufacturer the perfection which he should strive to reach, with the minimum expense of time, labour, and materials. For this end I instituted the following researches : I first examined fresh commercial specimens of bleaching powder ; 1 00 grains of these afforded from 20 to 28 grains of chlorine. This is the widest range of result, and it is undoubtedly considerable ; the first being to the second, as 100 to 71. The first yielded, by saturation with muriatic acid, 82 grains of chloride of calcium, equivalent to about 41 of lime; it contained besides 26 per cent, of water, and a very little common muriate ready formed. On heating such powder in a glass apparatus, it yielded at first a little chlorine, and then oxygen tolerably pure. The bulk of chlorine did not exceed one- tenth of the whole gaseous product. Of the recently prepared powder of another PP LIM 578 LIM manufacturer, 100 grains were found to give, by solution in acid, 23 grains of chlorine, and there remained, after evaporation and gentle ignition, 92 grains of muriate of lime, equiva- lent to about 46 of lime. Supposing this powder to have been nearly free from muriate, (and the manufacturers are anxious to prevent the deliquescent tendency which this intro- duces), we should have its composition as follows : Chlorine, 23 3-5 Lime, 46 one atom 3-5x2= 7-0 Water, 31 100 This powder being well triturated with different quantities of water at 60, yielded filtered solutions of the following densities at the same temperature : Sp. gr. 95 water + 5 bleaching powder, 1-0245 90 +10 1-0470 80 + 20 1-0840 The powder left on the filter, even of the second experiment, contained a notable quan- tity of chlorine, so that the chloride is but sparingly soluble in water; nor could I ever observe that partition occasioned by water in the elements of the powder, of which Mr. Dalton and M. Welter speak. Of the solution 80 + 20, 500 grains, apparently corresponding to 100 grains of powder, gave off, by saturation with muriatic acid, 19 grains of chlorine, and the liquid, after evaporation and ignition, afforded 41-8 grains of chloride of calcium, equivalent to 21 of lime. Here 4 per cent, of chlorine seem to have remained in the un- dissolved calcareous powder, which indeed, on examination, yielded about that quantity. But the dissolved chloride of lime consisted of 19 chlorine to 21 lime ; or of 4-5 atoms of the former, to almost exactly 5 (which is no atomic proportion) of the latter. The two-thirds of a grain of lime existing in lime water, in the five hundred grains of solu- tion, will make no essential alteration on the statement. Now, the above bleaching powder must have contained very little muriate of lime, for it was not deliquescent. Being thus convinced, both by examining the pure chloride of my own preparation, as well as that of commerce, that no atomic relations are to be observed in its constitution, for reasons already assigned, I ceased to prosecute any more researches in that direction. When we are desirous of learning minutely the proportion between the chloride and mu- riate of lime in bleaching powder, pure vine- gar may be used as the saturating acid. Having thus expelled the chlorine, we eva- porate to dryness, and ignite, when the acetate of lime will become carbonate, which will be separated from the original muriate by solution and filtration. I have found, on trial, the method by carbonic acid to be exceedingly slow and unsatisfactory. After passing a current of this gas for a whole day through the chloride diffused in tepid water, I found the liquid still to possess the power of discharging the colour very readily from litmus paper. But the doctrine of equivalents furnishes a very elegant theorem with acetic acid, whose con- veniency and accuracy in application I have verified by experiment. An apparently com- plex, and very important problem of practical chemistry, is thus brought within the reach of the ordinary manufacturer. Since common fermented vinegar is permitted by law to con- tain a portion of sulphuric acid, which avarice often leads the retailer to increase, we cannot employ it in the present research. But strong vinegar prepared from pyrolignous acid, such as that with which Messrs. Turnbull and Ramsay have long supplied the London market, being entirely free from sulphuric acid, is well adapted to our purpose. With such acid, contained in a poised phial, fully saturate a given weight (say 100 grains) of the bleaching powder, contained in a small glass matrass, applying a gentle heat at last, with inclination of the mouth of the vessel, to expel the adhering chlorine. Note the loss of weight due to the disengagement of the gas. (If carbonic acid be suspected to be present, the gas may be received over mercury.) Evaporate the solution, consisting of acetate and muriate of lime, to dryness, by a regulated heat, and note the weight of the mixed saline mass. Then calcine this, at a very gentle red heat, till the acetic acid be all decomposed. Note the loss of weight. We have now all the data requisite for determining the proportion of the constituents without solution, filtration, or precipitation by reagents. PROBLEM I. To find the lime originally associated with the chlorine, or at least not combined with muriatic acid, and therefore converted into an acetate. Rule Subtract from the above loss of weight its twenty-fifth part, the remainder is the quantity of lime taken up by the vinegar. PROBLEM II. To find the quantity of muriate of lime in the bleaching powder. Rule Multiply the above loss of weight by 1-7, the product is the quantity of carbonate of lime in the calcined powder, which being subtracted from the total weight of the resi- duum, the remainder is of course the muriate of lime. We know now the proportion of chlorine, lime, and muriate of lime, in 100 parts ; the deficiency is the water existing in the bleaching powder. Thus, for example, I found 100 grains of a commercial chloride some time kept, to give off 21 grains of chlo- rine, by solution in dilute acetic acid. The solution was evaporated to dryness : of saline LIM 579 LIM matter 125-6 grains were obtained, which, by calcination, became 84-3, having thus lost A | O 41-3 grains. But 41-3^- =39-65 = lime 25 present, uncombined with muriatic acid. And 41-3 X 1-7= 70-2 = the carbonate of lime in the residuary 84-3 grains of calcined salts. Therefore, 84-3 70-2 = 14-1 muriate of lime. Now, by dissolving out the muriate of lime, and evaporating, I got 14 grains of it, and the remaining carbonate was 70-3 grains. Hence this powder consisted of chlorine 21, lime 39-65, muriate of lime 14, and water 25-35 = 100. Sulphate of indigo, largely diluted with water, has been long used for valuing the blanching power of chloride of lime ; and it affords, no doubt, a good comparative test, though from the variableness of indigo it can form no absolute standard. Thus I have found 3 parts of indigo, from the East Indies, to saturate as much bleaching powder as 4 parts of good Spanish indigo. M. Welter's method is the following: He prepared a solution of indigo in sulphuric acid, which he diluted, so that the indigo formed y^j. of the whole. He satisfied him- self by experiments, that 14 litres (854-4 cubic inches, or 3-7 wine gallons English) of chlorine, which weigh 65 1^ English grains, destroyed the colour of 164 litres of the above blue solution. He properly observes, that chlorine discolours more or less of the tincture, according to the manner of proceeding, that is, according as we pour the tincture on the aqueous chlorine, and as we operate at different times, with considerable intervals ; if the aqueous chlorine or chloride solution be con- centrated, we have the minimum of discolor- ation ; if it be very weak, the maximum. He says, that solution of indigo, containing about _gL_ part, will give constant results to nearly 3^, and to greater nicety still, if we dilute the chlorine solution, so that it shall amount to nearly one-half the volume of the tincture which it can discolour ; if we use the pre- caution to keep the solution of chlorine and the tincture in two separate vessels; and, finally, to pour both together into a third vessel. We should, at the same time, make a trial on another sample of chlorine whose strength is known, in order to judge accurately of the hue. On the whole, he considers that fourteen measures of gaseous chlorine can discolour 164 measures of the above indigo solution, being a ratio of nearly one to twelve. The advantage of the very dilute tincture obviously consists in this, that the excess of water condenses the chlorine separated from combination by the sulphuric acid, and con- fines its whole efficacy to the liquor ; whereas, from concentrated solutions, much of it escapes into the atmosphere. Though I have made very numerous experiments with the indigo test, yet I never could obtain such consistency of result as M. Welter describes : when the blue colour begins to fade, a greenish hue appears, which graduates into brownish- yellow by imperceptible shades. Hence an error of $ may readily be allowed, and even more, with ordinary observers. When a mixture of sulphuric acid, common salt, and black oxide of manganese, are the ingredients used, as by the manufacturer of bleaching powder, the absolute proportions are, 1 atom mur. of soda, 7.5 29.70 100.0 1 atom perox. of mang. 5.5 21-78 73.3 2 at. oil of vit. 1.846 12.25 48.52 163,3 25.25 100.00 And the products ought to be Chlorine disengaged, 1 atom 4.5 17-82 Sulphate of soda, 1 9.0 35.64 Protosulphate of mang. 1 9.5 37-62 Water, ... 2 2.25 8.92 25.25 100.00 These proportions are, however, very dif- ferent from those employed by many, nay, I believe, by all manufacturers ; and they ought to be so, on account of the impurity of their oxide of manganese. Yet making allowance for this, I am afraid that many of them com- mit great errors in the relative quantities of their materials. From the preceding computation, it is evi- dent that 1 ton of salt with 1 ton of the above native oxide of manganese properly treated, would yield 0.59 of a ton of chlorine, which would impregnate 1.41 tons of slacked lime, producing 2 tons of bleaching powder, stronger than the average of the commercial specimens ; or allowing for a little loss, which is unavoid- able, would afford 2 tons of ordinary powder, with a little more slacked lime. MM. Orfila, Leseure, Gerdy, and Hennelle, having to examine the body of an individual who was supposed to have been poisoned, and who had been dead for nearly a month, found the smell so insupportable that they were in- duced to try the application of the chloride of lime, as recommended by M. Labarraque. A solution of this substance was frequently sprinkled over the body, and produced quite a wonderful effect, for scarcely had they made a few aspersions, when the unpleasant odour was instantly destroyed, and the operation was pro- ceeded in with comparative comfort. Since the above experiment, a commission was appointed by the prefect of the police in Paris to clear out offensive drains, in the ex- ecution of which much benefit to the protec- tion of the workmens' health was derived from chloride of lime. M. Gaultier de Claubry, after stating, as I have shown above, that car- bonic acid expels the chlorine from the chlo- ride of lime, proposes, as the best and most durable means of disinfecting the air in hospi- pp2 LIM 580 LIM tals, &c. to expose a considerable surface of chloride of lime in the apartments of the sick, whence the chlorine will be slowly and steadily evolved by the carbonic acid of the atmosphere, without annoying the patients in the slightest degree. This is the only plan admissible with chlorine where the apartments cannot be emptied. Where they can, the method de- scribed under FUMIGATION is more energetic. LIMESTONE. A genus of minerals, which Professor Jameson divides into the four following species : 1 . Rhomb-spar ; 2. Dolo- mite ; 3. Limestone ; and, 4. Arragonite. We shall consider the third species here. The same mineralogist divides limestone into twelve sub-species. 1. Foliated limestone; of which there are two kinds calcareous spar, and foliated gra- nular limestone. The first will be found in its alphabetical place in the Dictionary. Granular foliated limestone. Colour white, of various shades; sometimes it is spotted. Massive, and in distinct angulo-granular con- cretions. Lustre glistening, between pearly and vitreous. Fracture foliated. Translu- cent. Hard as calcareous spar. Brittle. Sp. gr. Carrara marble 2.717' It generally phosphoresces when pounded, or when thrown on glowing coals. Infusible. Effervesces with acids. It is a pure carbonate of lime. It occurs in beds in granite, gneiss, &c and rarely in secondary rocks. It is found in all the great ranges of primitive rocks in Europe. Parian marble, Pentelic marble, the Marmo Greco, the white marble of Luni, of Carrara, and of Mount Hymettus, the translucent white marble of statuaries, and flexible white marble, are the chief of the white marbles which the ancients used for sculpture and architecture. The red antique marble, Rosso antico of the Italians, and Egyptian of the ancients ; the Verde antico, an indeterminate mixture of white marble and green serpentine ; yellow antique marble ; the antique Cipolin marble, marked with green-coloured zones, caused by talc or chlorite ; and African breccia marble, are the principal coloured marbles of the an- cients. The Scottish marbles are, the red and white Tiree, the former of which contains hornblende, sahlite, mica, and green earth; the lona marble, harder than most others, consisting of limestone and tremolite, or oc- casionally a dolomite ; the Skye marble ; the Assynt in Sutherland, introduced into com- merce by Mr. Joplin, of Gateshead. It is white and grey, of various shades. The Glen- tilt marble ; the Balachulish ; the Boyne ; the Blairgowrie; and the Gknavon. Hitherto but few marbles of granular foliated limestone have been quarried in England. The Mona marlle is not unlike Verde antico. The black marbles of Ireland, now so generally used by architects, are Lucullites. The Toreen in the county of Waterford, is a fine variegated sort ; and a grey marble beautifully clouded with white, has been found near Kilcrump, in the same county. At Loughlougher, in Tippe> rary, a fine purple marble is found. The county of Kerry affords several variegated marbles. Of the continental marbles a good account is given by Professor Jameson, Mine- ralogy, vol. ii. p. 502. 2d Sub-species. Compact limestone; of which there are three kinds common com- pact limestone, blue Vesuvian limestone, and roes tone. Common compact limestone has usually a gray colour, with coloured delineations. Mas- sive, corroded, and in various extraneous shapes. Dull. Fracture fine splintery. Trans- lucent on the edges. Softer than the pre- ceding sub-species. Easily frangible. Streak grayish- white. Sp. gr. 2-0 to 2.7. It effer- vesces with acids, and burns into quicklime. It is a carbonate of lime, with variable and generally minute proportions of silica, alu- mina, iron, magnesia, and manganese. It occurs principally in secondary formations, along with sandstone, gypsum, and coal. Many animal petrifactions, and some vege- table, are found in it. It is rich in ores of lead and zinc ; the English mines of the for- mer metal being situated in limestone. When it is so hard as to take a polish, it is worked as a marble, under the name of shell, or liimac- cella marble. It abounds in the sandstone and coal formations, both in Scotland and England ; and in Ireland it is a very abundant mineral in all the districts where clay-slate and red sandstone occur. The Florentine marble, or ruin marble, is a compact lime- stone. Seen at a distance, slabs of this stone resemble drawings done in bistre. 2. Blue Vesuvian limestone. Colour dark bluish-grey, partly veined with white. Rolled and uneven on the surface. Fracture fine earthy. Opaque. Streak white. Semi-hard in a low degree. Feels heavy. Its consti- tuents are, lime 58, carbonic acid 28.5, water somewhat ammouiacal 11, magnesia 0.5, oxide of iron 0.25, carbon 0-25, and silica 1.25. Klaproth. It is found in loose masses among unaltered ejected minerals, in the neighbour- hood of Vesuvius. In mosaic work, it is used for representing the sky. 3. Roestone. Colours brown and grey. Massive, and in" distinct concretions, which are round granular. Dull. Opaque. Frac- ture of the mass round granular. Approach- ing to soft. Brittle. Sp. gr. 2.G to 2.68. It dissolves with effervescence in acids. It occurs along with red sandstone and lias limestone. In England this rock is called Bath-stone, Ketton-stone, Portland-stone, and Oolite. It extends, with but little interrup- tion, from Somersetshire to the banks of the Humber in Lincolnshire. It is used in archi- tecture, but it is porous, and apt to moulder away, as is seen in the ornamental work of the Chapel of Henry VII. LIM 581 LIM 3d, Sub-species. Chalk, which see. 4th, Agaric mineral, or Rock-milk. Co- lour white. In crusts or tuberose pieces. Dull. Composed of fine dusty particles. Soils strongly. Feels meagre. Adheres slightly to the tongue. Light, almost supernatant. It dissolves in muriatic acid with effervescence, being a pure carbonate of lime. It is found -on the north side of Oxford, between the Isis and the Cherwell, and near Chipping Norton ; as also in the fissures of limestone caves on the continent. It is formed by the attrition of water on limestone rocks. 5th Sub-species. Fibrous limestone; of which there are two kinds satin-spar, or the common fibrous; and fibrous calc-sinter. Satin-spar. White of various shades. Mas- sive, and in distinct fibrous concretions. Lustre glistening and pearly; fragments splintery; feebly translucent ; as hard as calcareous spar ; easily frangible ; sp. gr. 2-7- Its constituents are, lime 50.8, carbonic acid 47.6 ? Stromeyer says it contains some per cents, of gypsum. It occurs in thin layers in clay-slate at Al- stone-moor in Cumberland; in layers and veins in the middle district of Scotland, as in Fifeshire. It is sometimes cut into necklaces, Fibrous calc-sinter. It is used as marble, and the ancients formed it into unguent vases, the alalasler-lox of Scripture. See CALK- SINTER. 6th Sub-species. Tufaceous limestone, or Calc-tuff. Colour gray. Massive, and in imi- tative shapes, enclosing leaves, bones, shells, &c. Dull. Fracture fine grained uneven. Opaque. Soft. Feels rough. Brittle. It is pure carbonate of lime. It occurs in beds, generally in the neighbourhood of rivers; near fctarly-burn in Fifeshire, and other places. Used for lime. 7th Sub-species. Pisiform limestone, or Peastone. Colour yellowish-white. Massive, and in distinct concretions, which are round granular, composed of others which are very thin and concentric lamellar. In the centre there is a bubble of air, a grain of sand, or of some mineral matter. Dull. Fracture even. Opaque. Soft Brittle. Sp. gr. 2-532. It is carbonate of lime. It is found in great masses in the vicinity of Carlsbad in Bo- hemia. 8th Sub-species. Slate-spar. Schieferspath. Colour white, of various shades. Massive, and in distinct curved lamellar concretions. Lustre glistening and pearly. Feebly trans- lucent Soft; between sectile and brittle. Feels rather greasy. Sp. gr. 2-63. Its con- stituents are, carbonate of lime, with three per cent, of oxide of manganese. It occurs in primitive limestone, in metalliferous beds, and in veins. It is found in Glentilt; in Assynt; in Cornwall; and near Granard in Ireland. i)th Sub-species. Aphrite, which sec. 10th Sub-species. Lucullite; of which there are three kinds compact, prismatic, and fo- liated. 1. Compact is subdivided into the com- mon or black marble ; and the stinkstone. a. The common compact. Colour gray- ish-black. Massive. Glimmering. Fracture fine grained uneven. Opaque. Semi-hard. Streak dark ash-gray. Brittle. Sp. gr. 3. When two pieces are rubbed together, a fetid urinous odour is exhaled, which is increased by breathing on them. It burns white, but forms a black-coloured mass with sulphuric acid. Its constituents are, lime 53.38, car- bonic acid 41.5, carbon 0-75, magnesia and oxide of manganese 0.12, oxide of iron 0.25, silica 1.13, sulphur 0.25, muriates and sul- phates of potash with water 2.62. John. It is said to occur in beds in primitive and older secondary rocks. Hills of this mineral occur in the district of Assynt in Sutherland. Va- rieties of it are met with in Derbyshire ; at Kilkenny ; in the counties of Cork and Gal- way. The consul Lucullus admired it so much, as to give it his name. It is the Nero antico of the Italians. b. Stinkstone or Swinestone. Colour white, of many shades, cream, yellow, gray, black, and brown. Massive, disseminated, and in distinct granular concretions. Dull. Frac- ture splintery. Opaque. Semi-hard. Streak grayish- white. Emits a fetid odour on fric- tion. Brittle. Sp. gr. 2.7- The same che- mical characters as the preceding. Its consti- tuents are, 88 carbonate of lime, 4.13 silica, 3.1 alumina, 1.47 oxide of iron, 0.58 oxide of manganese, 0.30 carbon, 0-58 lime; sulphur, alkali, salt, water, 2.20 John. It occurs in beds in secondary limestone, alternating oc- casionally with secondary gypsum and beds of clay. It is found in the vicinity of North- Berwick, resting on red sandstone, and in the parish of Kirbean in Galloway. It is em- ployed for burning into lime. 2. Prismatic lucullite. Colours black, gray, and brown. Massive, in balls, and in distinct concretions. External surface some- times streaked. Internal lustre shining. Cleavage threefold. Translucent on the edges. Semi-hard. Streak gray coloured. Brittle. When rubbed it emits a strongly fetid urinous smell. Sp. gr. 2.67' When its powder is boiled in water, it gives out a transient hepatic odour. The water becomes slightly alkaline. It dissolves with effervescence in muriatic acid, leaving a charcoaly residuum. Its constituents resemble those of the preceding. It occurs in balls, in brown dolomite, at Building-hill, near Sunderland. It was at one time called ma- dreporite. 3. Foliated or sparry lucullite. Colours white, gray, and black. Massive, dissemi- nated and crystallized in acute six-sided py- ramids. Internal lustre glimmering. Frag, ments rhomboidal. Translucent. Semi-hard, LIT 582 LIT Brittle. Emits on friction a urinous smell. Sp. gr. 2.65. In other respects similar to the preceding. It is found in veins at Andreas- berg in the Hartz. llth Sub-species. Marie; of which there are two kinds, earthy and compact. Earthy marie has a gray colour, consists of fine dusty particles, feebly cohering ; dull ; soils slightly ; is light ; effervesces with acids ; and emits a urinous smell when first dug up. Its con- stituents are, carbonate of lime, with a little alumina, silica, and bitumen. It occurs in beds in the secondary limestone and gypsum formations in Thuringia and Mansfeld. Com- pact marie has a gray colour ; is massive, ve- sicular, or in flattened balls ; contains petri- factions; dull; fracture earthy, but in the great slaty ; yields to the nail ; opaque ; streak grayish- white ; brittle ; feels meagre ; sp. gr. 2.4. It intumesces before the blowpipe, and melts into a greenish-black slag. It effervesces with acids. Its constituents are, carbonate of lime 50, silica 12, alumina 32, iron and oxide of manganese 2 Kirwan. It occurs in beds in the secondary floetz limestone. It is fre- quent in the coal formations of Scotland and England. 12th Sub-species. Bituminous marie- slate. Colour grayish-black. Massive, and frequently with impressions of fishes and plants. Lustre glistening. Fracture slaty. Opaque. Shining streak. Soft. Sectile. Frangible. Sp. gr. 2-66. It is said to be carbonate of lime, with albumen, iron, and bitumen. It occurs in floetz limestone. It frequently contains cupreous minerals, petrified fishes, and fossil remains of cryptogamous plants. It abounds in the Hartzgebirge Jameson. LIQUEFACTION. A chemical term, in some instances synonymous with the word fusion, in others with the word deliquescence, and in others again with the word solution. LIQUIDITY. See CALORIC. LIQUOR of FLINTS. See SILICA. LITHIA. A new alkali. It was dis- covered by M. Arfredson, a young chemist of great merit, employed in the laboratory of M. Berzelius. It was found in a mineral from the mine of Uten in Sweden, called petalite by M. d'Andrada, who first distinguished it. Sir H. Davy demonstrated by voltaic electricity that the basis of this alkali is a metal, to which the name of lithium has been given. Berzelius gives the following simple process as a test for lithia in minerals: A fragment of the mineral, the size of a pin's head, is to be heated with a small excess of soda, on a piece of platinum foil, by a blowpipe for a couple of minutes. The stone is decomposed, the soda liberates the lithia, and the excess of alkali preserving the whole fluid at this temperature, it spreads over the foil, and surrounds the decomposed mineral. That part of the platinum near to the fused alkali becomes of a dark colour, which is more intense, and spreads over a larger sur- face, in proportion as there is more lithia in the mineral. The oxidation of the platinum does not take place beneath the alkali, but only around it, where the metal is in contact with both air and lithia. Potash destroys the reaction of the platinum on the lithia, if the lithia be not redundant. The platinum re- sumes its metallic surface, after having been washed and heated. Lithia may be obtained by fusing petalite with potash, dissolving the whole in muriatic acid, evaporating to dryness, and digesting in alcohol. The muriate of lithia being very so- luble in that fluid, is taken up, while the other salts remain. By a second evaporation and solution in alcohol, it is obtained perfectly pure. The muriate is itself a salt very charac- teristic of the alkali. It may easily be decom- posed by carbonate of silver ; and the carbo- nate thus procured, when treated with lime, yields pure lithia. Dr. Gmelin fused petalite with five times its weight of nitrate of barytes, at a white heat, in a platinum crucible; di- gested the mass in muriatic acid ; evaporated the solution to dryness; dissolved in water; se- parated the silica ; and added rather more sul- phuric acid than was equivalent to the barytes. The sulphate of barytes was got rid of by so- lution in water and filtration. The liquid was now concentrated by evaporation to expel the excess of muriatic acid. It was then supersa- turated with carbonate of ammonia, which threw down the alumina and the oxide of iron. The filtered liquid was evaporated to dryness and the residue was ignited, to drive off the ammoniacal sulphate and muriate. The re- mainder was dissolved in water, and hydrosul- phuret of ammonia was added to the solution to separate the manganese. Being now filter- ed, evaporated, and ignited, it was pure sul- phate of lithia, from which he obtained the car- bonate by adding acetate of barytes, and de- composing the resulting acetate of lithia by a red heat. The first is the process of M. Vauquelin, and is vastly the simpler of the two. M. Berzelius says that the most economi- cal way of preparing lithia is to mix triphane or spodumene in powder with twice its weight of pulverized fluor spar and with sulphuric acid ; then to heat the mixture till the fluoric acid with the silica is volatilized, and after- wards to separate the sulphate of lithia by solution. M. Berzelius has found lithia to be a con- stant and essential element in the mineral waters of Bohemia. To detect and separate the lithia, he pours a solution of phosphate of soda into the mineral water, evaporates to dryness, and redissolves in cold water. The lithia is left in the state of an insoluble phos- phate of lithia and soda. The most complete account, which we have of lithia and its compounds, is that of Dr. LIT 583 LIT Gmelin. He had the benefit indeed of M. Vauquelin' s very able researches, published in the Ann. de Chimie et de Phys. vii. 287- Dr. Gmelin's memoir is inserted in the 62nd volume of Gilbert's Annalen. Caustic lithia has a very sharp burning taste. It destroys the cuticle of the tongue like pot- ash. It does not dissolve with great facility in water, and appears not to be much more soluble in hot than in cold water. In this respect it has an analogy with lime. Heat is evolved du- ring its solution in water. When exposed to the air it does not attract moisture, but absorbs carbonic acid, and be- comes opaque. When exposed for an hour to a white heat in a covered platinum crucible its bulk does not appear to be diminished : but it has absorbed a quantity of carbonic acid. It dissolves only in small quantity in alco- hol of the specific gravity 0-85. When weak alcohol is added to an aqueous solution of lithia in a well stopped phial, no change takes place at first ; but after some hours the lithia precipitates in the state of a white powder. Lithia unites with sulphur according to Vauquelin. Sulphuret of lithia has a yellow colour, dissolves readily in water, and is de- composed by acids in the same way as the other alkaline sulphurets. Phosphorus decomposes water with the help of caustic lithia. If we heat in a retort phos- phorus with a solution of caustic lithia in water, phosphuretted hydrogen gas is disen- gaged, which catches fire when it comes into the air. Neutral sulphate of lithia forms small prismatic crystals, having a good deal of lustre, sometimes constituting pretty long but narrow tables. When exposed to the air, they undergo only an insignificant efflores- cence. This salt has a saline and scarcely bitter taste. It dissolves pretty readily in water, and melts when exposed to a tempe- rature scarcely reaching a red heat. BisulpJiate of lithia dissolves in water with greater facility than the neutral salt. It forms six-sided tables, in which two of the faces, which are parallel to each other, far exceed the remaining ones in length. When exposed to a very high temperature, it gives out sul- phurous acid and oxygen gas, and is converted into the neutral sulphate. According to Arfredson, thisbisalt dissolves with more difficulty in water than the neutral salt. Phosphate of lithia. Phosphoric acid when dropped into the solution of sulphate of lithia occasions no precipitate. But when the uncom- bined acid is saturated by ammonia, the phos- phate of lithia is precipitated in the state of white flocks, which are insoluble in water. When a drop of phosphoric acid is let fall into a very dilute solution of carbonate of lithia, no precipitate falls ; but when the liquid is heated, the carbonic acid gas is disengaged, and phosphate of lithia falls down. From this it would seem, that the solubility of phosphate of lithia in water is owing to the presence of the carbonic acid. There exists likewise a I iphosphate of lithia. It is obtained by dissolving the neutral salt in phosphoric acid. By a very slow evaporation of this solution, we obtain transparent granu- lar crystals. Nitrate of lithia forms four-sided prisms with rhomboidal bases. It has a very pun- gent taste, and seems to surpass almost all other salts in deliquescency. In a very hot day, it crystallized in the sun ; but deliquesced again in the shade. It dissolves in the strong- est alcohol. Carbonate of lithia constitutes a white pow- der. It dissolves with great difficulty in cold water. According to Vauquelin, 100 parts of water dissolve scarcely one part of this salt. It is more soluble in hot water. A solution of carbonate of lithia containing only l-1000th of its weight of the salt, acts strongly as an alkali. 0-535 of a gramme of fused carbonate of lithia were, by means of sulphuric acid and exposure to a strong heat, converted into 0-765 of neutral sulphate of lithia. Now this quan- tity of sulphate contains 0-2436 of lithia. Hence 0-535 of carbonate of lithia are com- posed of Lithia, 0-2436 Carbonic acid, 0-2914 Or in the 100 parts, Lithia, Carbonic acid, 0-5350 45-54 54.46 100-00 But the oxygen in 45.54 lithia is = 19-09 54-46 carbonic acid = 39-59 and 2 X 19-09 = 38-18, a number differing but little from 39-59. The solution of carbonate of lithia is decom- posed by lime and barytes water. It is inso- luble in alcohol. The platinum crucible in which carbonate of lithia has been exposed to a red heat, gives obvious indications of having been attacked, its surface assuming a dark olive-green colour ; but the metallic lustre is again restored by rubbing the crucible with coarse sand and water. Muriate of lithia forms small regular cubes very similar to common salt in their taste. The easiest method of obtaining the crystals, is to expose the solution to the sun in a hot day. The crystals deliquesce very speedily when exposed to the air, but not with so much rapidity as nitrate of lithia. This salt does not melt when exposed to the red heat pro- duced by the action of a spirit lamp ; but when exposed in a platinum crucible, not completely LIT 584 LIT covered, to an incipient white heat, it is fused into the chloride. Chromate of lithia forms orange-yellow crystals, which appear to contain an excess of acid. They are oblique parallelepipeds with rhomboidal bases. Sometimes they exhibit a dendritrical vegetation. This salt is soluble in water. Oxalate of Hilda. A portion of carbonate of lithia was saturated with oxalic acid. The neutral salt crystallizes with difficulty. The crystals have the appearance of small opaque protuberances, and dissolve with facility in water. To the neutral solution of oxalate of lithia was added a quantity of oxalic acid, exactly equal to that already combined with the lithia. By evaporation, small transparent granular crystals of blnoxalate of lithia were obtained. They appeared to dissolve with facility in water, though not to be so soluble as the neutral salt. Neutral tartrate of lithia dissolves with facility in water, but does not crystallize, form- ing a white opaque mass, which does not de- liquesce when exposed to the air. When tar- taric acid is added to the solution of the neutral tartrate, no crystallizable bitartrate is formed ; but perhaps we may deduce the existence of such a salt from the fact that when the solu- tion is evaporated no crystals of tartaric acid make their appearance. When the solution is evaporated to dryness, we obtain a white opaque mass, which exhi- bits no appearance of crystallization, and which dissolves with facility in water. Acetate of lithia^ when evaporated, forms a syrupy mass, which cracks on cooling; so that the glass looks as if it had burst. This matter deliquesces in the air, and sometimes, while attracting moisture, crystalline plates appear in it. Tartrate of lithia and potash. If the ex- cess of the acid of bitartrate of potash be satu- rated by means of carbonate of lithia, we obtain by spontaneous evaporation, a salt .which forms large crystals, having the shape of four-sided prisms terminated by parallelograms, with an- gles very nearly right. The diagonals of these terminal faces are distinctly marked, and the four triangles formed by means of them are streaked parallel to the edges of these faces. This salt dissolves readily in water, and has a saline and scarcely bitter taste. When ex- posed to the air, it effloresces slightly, and only on the surface. Tartrate of lithia and soda. Bitartrate of soda was neutralized by means of carbonate of lithia. By spontaneous evaporation, the liquid deposited long rectangular four-sided prisms, frequently terminated by an oblique face. This salt dissolves with facility in water, and efflo- resces only slightly, and on the surface. Its taste is purely saline, and not strong. Muriate of platinum does not form a double salt with muriate of lithia. Potash and lithia, therefore, may be very well distin- guished from each other by means of muriate of platinum. From the preceding account of the salts of lithia, we see that they have many properties in common with the salts of soda. Like them they are neither precipitated by muriate of platinum, nor by tartaric acid. They may however be distinguished from the salts of soda by the following properties : When their concentrated solutions are mixed with a con- centrated solution of carbonate of soda, a pre- cipitate falls. They are likewise precipitated by phosphate of soda and phosphate of ammonia, when no uncombined acid is pre- sent In reference to analytical chemistry, it may be remarked, that lithia, potash, and soda, if they should exist in the same compound, may be separated in the following way : Lithia may be precipitated by means of phosphoric acid and an excess of caustic ammonia. The phosphate of lithia may be dissolved in acetic acid, and the phosphoric acid precipitated by means of acetate of lead, &c. When lithia exists in a compound with pot- ash, this last alkali may be precipitated by. means of muriate of platinum. F:,om the results of the preceding experi- ments we see, says Dr. Gmelin, that if 10 be the equivalent number for oxygen, the equi- valent number for lithium is 13-83, and for lithia 23-83 ; that for carbonate of lithia by calculation, 51-32; but according to the pre> ceding experiment, 52-32, &c. Placed in the voltaic circuit, Sir H. Davy showed, that it was decomposed with the same phenomena as the other alkalis. A portion of its carbonate being fused in a platinum cap- sule, the platinum was rendered positive, and a negative wire brought to the upper surface. The alkali decomposed with bright scintilla- tions, and the reduced metal being separated, afterwards burned. The particles were very similar to sodium. A globule of quicksilver made negative, and brought into contact with the alkaline salt, soon became an amalgam of lithium, and had gained the power of acting on water, with the evolution of hydrogen, and formation of alkali. M. Vauquelin concludes, from his experi- ments, that 100 parts of lithia contain 43-5 of oxygen, and 56-5 of metallic base ; a quan- tity which, he observes, is greater than that of all the other alkalis. The Editors of the Ann. de Chimie remark, that, according to this estimate, the equivalent number of the metal is 12-97, of its oxide 22-97, of its dry sulphate 72-97, and of its crystallized sulphate 82-97- These numbers are adapted to the oxygen radix of 10. Dr. Gmelin's analysis of lithia makes its composition to be, by his own reduction, LOA 585 LUN Lithium, Oxygen, 58-05 41-95 100-00 His neutral sulphate consists of, Crystallized. Dry. Sulphuric acid, 58-34 68-15 5-000 Lithia, 27-25 31-85 2-3367 Water, 14-41 The prime equivalent of lithia inferred from this analysis approaches much nearer to M. Vauquelin's number than that deduced by Dr. Gmelin himself. If we convert this prime ratio into per cent, proportions, we shall have lithia a compound of Lithium, 57-205 1-3367 Oxygen, 42-795 1-0000 From his analysis of the carbonate, the prime equivalent of lithia comes out, as nearly as possible, 2-3. We are therefore warranted to consider 1-3 as the prime of lithium, from the concurring experiments both of M. Vau- quelin and Dr. Gmelin. I cannot see how the Doctor's own ingenious and accurate experi- ments on these two salts permitted him to make so erroneous an estimate of the equiva- lent of lithia, as 23-83, instead of 23 or 23. LITHIC ACID. See ACID (LiTHic). LITHOM ARGE. Stone-marrow, a mine- ral of which there are two kinds, the friable, and indurated. Friable Lithomarge. Colour white, mas- sive, and sometimes in crusts. Particles scaly, and feebly glimmering. Streak shining. Slightly cohering. Soils slightly. Feels rather greasy. Adheres to the tongue. Light. Phosphoresces in the dark. Its constituents are, silica 32, alumina 26.5, iron 21, muriate of soda 1.5, and water 17.0. Klaprotli, It occurs commonly in tin-stone veins. Indurated Lithomarge. Colours yellowish and reddish white. Massive, and amygda- loidal. Dull. Fracture line earthy. Opaque. Streak shining. Soft, sectile, and easily frangible. Adheres strongly to the tongue. Feels fine, and greasy. Sp. grav. 2.44. In- fusible before the blowpipe : some varieties phosphoresce, and others, when moistened, afford an agreeable smell like that of nuts. Its constituents are, silica 45.25, alumina 36.5, oxide of iron 2.75, water 14, and a trace of potash Klaproth. It occurs in veins in porphyry, gneiss, &c. at Rochlitz in Saxony, and at Zb'blitz. Jameson. LITMUS. See ARCHIL. LIVER OF SULPHUR. See SUL- PHUR. LIXIVIATION. The application of water to the fixed residues of bodies, for the purpose of extracting the saline part. LIXIVIUM. A solution obtained by lixiviation. LOADSTONE. See ORES OF IRON. LOAM. See CLAY. LOBOITE. A magnesian idocrase from Norway. LOGWOOD. The tree which yields it is called by Linnaeus, Hamatoxylum campe- chianum. Logwood is so heavy as to sink in water, hard, compact, of a fine grain, capable of being polished, and scarcely susceptible of decay. Its predominant colour is red, tinged with orange, yellow, and black. It yields its colour both to spirituous and watery menstrua. Alcohol extracts it more readily and copiously than water. The colour of its dye is a fine red, inclining a little to violet or purple, which is principally observa- ble in its watery decoction. This, left to itself, becomes in time yellowish, and at length black. Acids turn it yellow ; alkalis deepen its colour, and give it a purple or violet hue. Stuffs would take only a slight and fading colour from decoction of logwood, if they were not previously prepared with alum and tartar. A little alum is added also to the bath. By these means they acquire a pretty good violet. A blue colour may be obtained from log- wood, by mixing verdigris with the bath, and dipping the cloth till it has acquired the proper shade. The great consumption of logwood is for blacks, to which it gives a lustre and velvety cast, and for greys of certain shades. It is also of very extensive use for different com- pound colours, which it would be difficult to obtain of equal beauty and variety, by means of drugs affording a more permanent dye. Juice of logwood is frequently mixed with that of brasil, to render colours deeper ; their proportion being varied according to the shade desired. Logwood is used for dyeing silk violet. For this, the silk must be scoured, alumed, and washed; because, without aluming, it would take only a reddish tinge, that would not stand wetting. To dye silk thus, it must be turned in a cold decoction of logwood till it has acquired the proper colour : if the de- coction were used hot, the colour would be in stripes and uneven. Bergmann has already observed, that a fine violet might be produced from logwood, by impregnating the silk with solution of tin. In fact, we may thus obtain, particularly by mixing logwood and brasil in various propor- tions, a great number of fine shades, more or less inclined to red, from lilac to violet. See HEMATIN. LOMON1TE, or LAUMONITE. Di- prismatic ZEOLITE. LUCULLITE. See LIMESTONE, 10th species. LUMACHELLA. See LIMESTONE. LUNA CORNEA. Muriate of silver. See SILVER. MAD 586 MAD LUNAR CAUSTIC. Nitrate of silver, fused in a low heat. See SILVER. LUPULIN. M. Planche first ascertained that the three active ingredients of hop, the oil. resin, and bitter principle, reside in the brilliant yellow grains scattered over the cali- cinal scales of the cones which serve as their envelope. Dr. Ives, of New York, and MM. Payen and Chevalier, have since confirmed this position. This matter, when insulated, is of a golden yellow colour, in little grains, formed of an impalpable powder, without con- sistence, which attaches itself to the fingers and renders them rough. It has a penetrating aromatic odour. 200 grammes of this sub- stance being put into a retort, with 300 grammes of distilled water, the mixture was subjected to distillation, and afforded water and oil of an odour entirely similar to that of this yellow matter; but much more penetrating, narcotic, and very acrid in the throat. This solution is soluble in a great measure in water. The total amount is about 2 per cent, of the yellow matter employed ; and as this yellow matter is contained in hop, in the proportion of -J^-, it follows that the hop contains about 2 parts in the thousand of essential oil. The following ingredients were extracted by MM. Payen and Chevalier, from 200 parts of this yellow substance: 1, water; 2, essential oil ; 3, carbonic acid ; 4, sub-acetate of am- monia, generated in the distilled water after a few days; 4, traces of ozmazome; 6, traces of fatty matter; 7, gum; 8, malic acid; 9, malate of lime ; 10, bitter matter 25 parts ; 1 1 , a well-characterized resin, 105 parts; 12, silica, 8 parts ; 13, traces of carbonate, muriate, and sulphate of potash ; 1 4, carbonate and phosphate of lime ; 15, oxide of iron and traces of sulphur. The bitter matter introduced into the stomach destroys appetite. Journ. de Pharm. 1822. LUTE. The lutes with which the join- ings of vessels are closed are of different kinds, according to the nature of the operations to be made, and of the substances to be distilled in these vessels. When vapours of watery liquors, and such as are not corrosive, are to be contained, it is sufficient to surround the joining of the receiver to the nose of the alembic, or of the jjretort, with slips of paper or of linen, covered with flour-paste. In such cases also slips of wet bladder are very conveniently used. When more penetrating and dissolving vapours are to be contained, a lute is to be employed of quicklime slacked in the air, and beaten into a liquid paste with whites of eggs. This paste is to be spread upon linen slips, which are to be applied exactly to the joining of the vessels. This lute is very convenient, easily dries, becomes solid, and sufficiently firm. Of this lute, vessels may be formed hard enough to bear polishing on the wheel. Lastly, when acid and corrosive vapours are to be contained, we must then have recourse to the lute called fat lute. This lute is made by forming into a paste some dried clay finely powdered, sifted through a silken scarce, and moistened with water, and then by beating this paste well in a mortar with boiled linseed oil, that is, oil which has been rendered drying by litharge dissolved in it, and fit for the use of painters. This lute easily takes and retains the form given to it. It is generally rolled into cylinders of a convenient size. These are to be applied, by flattening them, to the join- ings of the vessels, which ought to be perfectly dry, because the least moisture would prevent the lute from adhering. When the joinings are well closed with this fat lute, the whole is to be covered with slips of linen spread with lute of lime, and whites of eggs. These slips are to be fastened with packthread. The second lute is necessary to keep on the fat lute, because this latter remains soft, and does not become solid enough to stick on alone. Fine porcelain clay, mixed with a solution of borax, is well adapted to iron vessels, the part received into an aperture being smeared with it. LYCOPODIUM. The fine dust of lyco- podium, or clubmoss, is properly the seeds of the plant, and when diffused or strewed in the air, it takes fire from a candle, and burns off like a flash of lightning. It is used in the London theatres. LYDIAN STONE. Flinty slate. LYTHRODES. See SCAPOLITE. M MACERATION, body in a cold liquor. MACLUREITE. BRUCITE. MADDER, a substance very extensively employed in dyeing, is the root of the rubia tinctorum. Although madder will grow both in a stiff clayey soil and in sand, it succeeds better in a The steeping of a moderately rich, soft, and somewhat sandy soil : it is cultivated in many of the provinces of France, in Alsace, Normandy, and Pro- vence: the best of European growth is that which comes from Zealand. The best roots are about the thickness of a goose quill, or at most of the little finger : they are semitransparent, and of a reddish colour ; MAD 587 MAD they have a strong smell, and the bark is smooth. Hellot ascribes the superiority of the madder which comes from the Levant to the circum- stance of its having been dried in the open air. The red colouring matter of madder may be dissolved in alcohol, and on evaporation a residuum of a deep red is left. Fixed alkali forms in this solution a violet, the sulphuric acid a fawn-coloured, and the sulphate of potash a fine red precipitate. Precipitates of various shades may be obtained by alum, nitre, chalk, sugar of lead, and the muriate of tin. The quantity of aqueous chlorine required to destroy the colour of a decoction of madder is double what is necessary to destroy that of a decoction of an equal weight of brasil wood. Wool would receive from madder only a perishable dye, if the colouring particles were not fixed by a base, which occasions them to combine with the stuff more intimately, and which in some measure defends them from the destructive influence of the air. For this purpose, the woollen stuffs are first boiled for two or three hours with alum and tartar, after which they are left to drain; they are then slightly wrung and put into a linen bag, and carried into a cool place, where they are suf- fered to remain for some days. The quantities of alum and tartar, as well as their proportions, vary much in different manufactories. Hellot recommends five ounces of alum and one ounce of tartar to each pound of wool ; if the proportion of tartar be increased to a certain degree, instead of a red, a deep and durable cinnamon colour is produced, because, as we have seen, acids have a tendency to give a yellow tinge to the colouring particles of madder. Berthollet found, that by em- ploying one-half tartar, the colour sensibly bordered more on the cinnamon than when the proportion was only one-fourth of the alum. In dyeing with madder, the bath must not be permitted to boil, because that degree of heat would dissolve the fawn-coloured particles, which are less soluble than the red, and the colour would be different from that which we wish to obtain. The quantity of madder which Mr. Poerner employs is only one-third of the weight of the wool, and Schaeffer advises only one-fourth. If wool be boiled for two hours with one- fourth of sulphate of iron, then washed, and afterward put into cold water with one-fourth of madder, and then boiled for an hour, a coffee colour is produced. Bergmann adds, that if the wool have not been soaked, and if it be dyed with one part of sulphate of iron and two of madder, the brown obtained borders upon a red. Berthollet employed a solution of tin in various ways, both in the preparation and in the maddering of cloth. He used different solutions of tin, and found that the tint was always more yellow or fawn-coloured, though sometimes brighter than that obtained by the common process. Mr. Guhliche describes a process for dyeing silk with madder : For one pound of silk he orders a bath of four ounces of alum, and one ounce of a solution of tin ; the liquor is to be left to settle, when it is to be decanted, and the silk carefully soaked in it, and left for twelve hours ; and after this preparation, it is to be immersed in a bath containing half a pound of madder softened by boiling with an infusion of galls in white wine : this bath is to be kept moderately hot for an hour, after which it is to be made to boil for two minutes. When taken from the bath, the silk is to be washed in a stream of water, and dried in the sun. Mr. Guhliche compares the colour thus ob- tained, which is very permanent, to the Turkey red. If the galls be left out, the colour is clearer. A great degree of brightness may be communicated to the first of these, by after- ward passing it through a bath of brasil wood, to which one ounce of solution of tin has been added: the colour thus obtained, he says, is very beautiful and durable. The madder red of cotton is distinguished into two kinds : one is called simple madder red; the other, which is much brighter, is called Turkey or Adrianople red, because it comes from the Levant, and has seldom been equalled in brightness or durability by our artists. Galls or sumach dispose thread and cotton to receive the madder colour, and the proper mordant is acetate of alumina. The nitrate and muriate of iron as a mor- dant produces a better effect than the sulphate and acetate of the same metal ; they afford a beautiful, well saturated violet colour. The Adrianople red possesses a degree of brightness, which it is difficult for us to approach by any of the processes hitherto mentioned. Some years ago, Mr. Papillon set up a dye- house for this red at Glasgow ; and in 1790 the commissioners for manufactures in Scot- land paid him a premium, for communicating his process to the late Prof. Black, on condition of its not being divulged for a certain term of years. The time being expired, it has been made public, and is as follows : Step. I. For 100 Ibs. of cotton, you must have 100 Ib. of Alicant barilla, 20 Ib. of pearl ashes, 100 Ib. of quicklime. The barilla is to be mixed with soft water in a deep tub, which has a small hole near the bottom of it, stopped at first with a peg. This hole is to be covered in the inside with a cloth supported by two bricks, that the ashes may be prevented from running out at it, or stopping it up, while the ley filters through it. Under this tub must be another, to receive the ley, and pure water is to be passed repeatedly MAD 588 MAG through the first tub, to form leys of different Strength, which are kept separate until their strength is examined. The strongest required For use must float an egg, and is called the ley of six degrees of the French hydrometer. The weaker are afterwards brought to this strength by passing them through fresh ba- rilla; but a certain quantity of the weak, which is of two degrees of the above hydro- meter, is reserved for dissolving the oil, the gum, and the salt, which are used in subse- quent parts of the process. This ley of two degrees is called the weak barilla liquor ; the other the strong. Dissolve the pearl ashes in ten pails, of four gallons each, of soft water, and the lime in fourteen pails. Let all the liquors stand till they become quite clear, and then mix ten pails of each. Boil the cotton in this mixture five hours, then wash it in running water, and dry it. Step. II. Bam bis, or gray steep. Take a sufficient quantity (ten pails) of the strong barilla water in a tub, and mix with it two pailfuls of sheep's dung ; then pour into it two quart bottles of sulphuric acid, one pound of gum-arabic, and one pound of sal ammoniac, both previously dissolved in a sufficient quantity of weak barilla water ; and, lastly, twenty-five pounds of olive oil, previously dissolved, or well mixed with two pails of the weak barilla water. The materials of this steep being well mixed, tread down the cotton into it until it is well soaked; let it steep twenty-four hours, then wring it hard, and dry it. Steep it again twenty-four hours, and again wring and dry it. Steep it a third time twenty-four hours, after which wring and dry it; and, lastly, wash it well, and dry it Step. III. The white steep This part of the process is precisely the same with the last in every particular, except that the sheep's dung is omitted in the composition of the steep. Step. IV. Gall steep Boil twenty-five pounds of bruised galls in ten pails of river water, until four or five are boiled away ; strain the liquor into a tub, and pour cold water on the galls in the strainer to wash out of them all their tincture. As soon as the liquor is become milk- warm, dip your cotton, hank by hank, handling it carefully all the time, and let it steep twenty- four hours. Then wring it carefully and equally, and dry it well without washing. Step. V. First alum steep. Dissolve twenty- five pounds of Roman alum in fourteen pails of warm water, without making it boil, skim the liquor well, add two pails of strong barilla water, and then let it cool until it is luke- warm. Dip your cotton, and handle it hank by hank, and let it steep twenty.four hours ; wring it equally, and dry it well without washing. Step. VI. Second alum steep. This is in every particular like the last ; but after the cotton is dry, steep it six hours in the river, and then wash and dry it. Step. VII. Dyeing steep The cotton is dyed by about ten pounds at once, for which take about two gallons and a half of bullocks' blood, mix it in the copper with twenty-eight pails of milk-warm water, stir it well, add twenty-five pounds of madder, and lastly, stir all well together. Then having beforehand put the cotton on sticks, dip it into the liquor, and move and turn it constantly one hour, during which gradually increase the heat until the liquor begins to boil at the end of the hour. Then sink the cotton, and boil it gently one hour longer ; and lastly, wash it and dry it. Take out so much of the boiling liquor, that what remains may produce a milk-warm heat with the fresh water with which the copper is again filled up, and then proceed to make up a dyeing liquor, as above, for the next ten pounds of cotton. Step. VIII. The fixing steep. Mix equal parts of the gray steep liquor and of the white steep liquor, taking five or six pails of each. Tread down the cotton into this mixture, and let it steep six hours : then wring it moderately and equally, and dry it without washing. Step. IX. Brightening steep. Ten pounds of white soap must be dissolved very carefully and completely in sixteen or eighteen pails of warm water: if any little bits of the soap remain undissolved, they will make spots in the cotton. Add four pails of strong barilla water, and stir it well. Sink the cotton in this liquor, keeping it down with cross sticks, and cover it up ; boil it gently two hours, then wash it and dry it, and it is finished. MADREPORES. A species of coral, the eoophyte of naturalists. They consist of car- bonate of lime, and a little animal membra- naceous substance. MAGISTERY. Chemists formerly applied this term to almost all precipitates : at present it is applied only to a few, which have retained the name from habitual usage. MAGISTERY OF BISMUTH. See BISMUTH. MAGNESIA. One of the primitive earths, having a metallic basis, called mag- nesium. It has been found native in the state of hydrate. Magnesia may be obtained, by pouring into a solution of its sulphate a solution of subcar- bonate of soda, washing the precipitate, drying it, and exposing it to a red heat. It is usually procured in commerce by acting on magnesian limestone with the impure muriate of magnesia, or bittern of the sea-salt manufactories. The muriatic acid goes to the lime, forming a so- luble salt, and leaves behind the magnesia of both the bittern and limestone. Or the bittern MAG 589 MAG is decomposed by a crude subcarbonate of am- monia, obtained from the distillation of bones in iron cylinders. Muriate of ammonia and subcarbonate of magnesia result. The former is evaporated to dryness, mixed with chalk, and sublimed. Subcarbonate of_ ammonia is thus recovered, with which a new quantity of bittern may be decomposed ; and thus in ceaseless repetition, forming an elegant and economical process. 100 parts of crystallized Epsom salt require for complete decomposi- tion 56 of subcarbonate of potash, or 44 dry subcarbonate of soda, and yield 16 of pure magnesia after calcination. Magnesia is a white, soft powder. Its sp. gr. is 2.3 by Kirwan. It renders the syrup of violets, and infusion of red cabbage, green, and reddens turmeric. It is infusible, except by the hydroxygen blowpipe. It has scarcely any taste, and no smell. It is nearly insoluble in water ; but it absorbs a quantity of that liquid with the production of heat. And when it is thrown down from the sulphate by a caustic alkali, it is combined with water, constituting a hydrate, which, however, separates at a red heat. It contains about one-fourth its weight of water. When magnesia is exposed to the air, it very slowly attracts carbonic acid. It combines with sulphur, forming a sulphuret. The metallic basis, or magnesium, may be obtained in the state of amalgam with mer- cury, by electrization, as is described under BARIUM; but a much longer time is neces- sary. Sir H. Davy succeeded also in decom- posing magnesia, by passing potassium in vapour through it, heated to whiteness, in a tube of platinum out of the contact of air. He then introduced a small quantity of mercury, and heated it gently for some time in the tube. An amalgam was obtained, which, by distil- lation, out of the contact of the atmosphere, afforded a dark grey metallic film, infusible at the point at which plate-glass softened, and which in the process of the distillation of the mercury rendered the glass black at its point of contact with it. This film burned with a red light when heated strongly, and became converted into a white powder, which had the character of magnesia. When a portion of magnesium was thrown into water, it sunk to the bottom, and effervesced slowly, becoming covered with a white powder. By adding a little muriatic acid to the water, the efferves- cence was violent. The metal rapidly disap- peared, and the solution was found to contain magnesia. No direct experiments have as yet been made, to determine the proportions of the elements in magnesia ; but from experiments made on the combination of this substance with sulphuric acid, assuming that they are in single proportions, Dr. Wollaston infers the equivalent of magnesia to be 2.46. Hence magnesium will be 1.46. M. Gay Lussac has lately experimented, with his characteristic accuracy, on the sulphate of magnesia, an-2 Sulphur, 4 13-8 The salts of mercury have the following general characters : 1. A dull red heat volatilizes them. 2. Ferroprussiate of potash gives a white precipitate. 3. Hydrosulphuret, black. 4. Muriate of soda, with the protosalts, white. 5. Gallic acid, orange yellow. 6. Plate of copper, quicksilver. The sulphuric acid does not act on this metal, unless it be well concentrated and boil- ing. For this purpose mercury is poured into a glass retort, with nearly twice its weight of sulphuric acid. As soon as the mixture is healed, a strong effervescence takes place, sulphurous acid gas escapes, the surface of the mercury becomes white, and a white powder is produced : when the gas ceases to come over, the mercury is found to be con- verted into a white, opaque, caustic, saline mass, at the bottom of the retort, which weighs one-third more than the mercury, and is decomposed by heat. Its fixity is consider- ably greater than that of mercury itself. If the heat be raised, it gives out a considerable quantity of oxygen, the mercury being at the same time revived. Water resolves it into two salts, the bisul- phate and subsulphate ; the latter is of a yel- low colour. Much washing is required to produce this colour, if cold water be used; but if a large quantity of hot water be poured on, it immediately assumes a bright lemon colour. In this state it is called turllth mi- neral. The other affords by evaporation, small, needly, deliquescent crystals. The fixed alkalis, magnesia, and lime, pre- cipitate oxide of mercury from its solutions ; these precipitates are reducible in closed ves- sels by mere heat without addition. The nitric acid rapidly attacks and dis- solves mercury, at the same time that a large quantity of nitrous gas is disengaged ; and the colour of the acid becomes green during its escape. Strong nitric acid takes up its own weight of mercury in the cold ; and this so- lution will bear to be diluted with water. But if the solution be made with the assistance of heat, a much larger quantity is dissolved ; and a precipitate will be afforded by the addition of distilled water, which is of a yellow colour if the water be hot, or white if it be cold ; and greatly resembles the turbith mineral produced with sulphuric acid : it has accordingly been called nitrous turbith. All the combinations of mercury and nitric acid are very caustic, and form a deep purple or black spot upon the skin. They afford crystals, which differ according to the state of the solution. When nitric acid has taken up as much mercury as it can dissolve by heat, it usually assumes the form of a white saline mass. When the combination of nitric acid and mercury is exposed to a gradual and long continued low heat, it gives out a portion of nitric acid, and becomes converted into a bright red oxide, still retaining a small portion of acid. This is known by the name of red precipitate, and is much used as an escharotic. When red precipitate is strongly heated, a large quantity of oxygen is disengaged, toge- ther with some nitrogen, and the mercury is sublimed in the metallic form. Nitrate of mercury is more soluble in hot than cold water, and affords crystals by cool- ing. It is decomposed by the affusion of a large quantity of water, unless the acid be in excess. A fulminating preparation of mercury was discovered by Mr. Howard. A hundred grains of mercury are to be dissolved by heat in an ounce and a half by measure of nitric acid. This solution being poured cold into two ounces by measure of alcohol in a glass vessel, heat is to be applied till effervescence is ex- cited. A white vapour undulates on the sur- face, and a powder is gradually precipitated, which is immediately to be collected on a filter, well washed, and cautiously dried with a very moderate heat. This powder detonates Icudly by gentle heat, or slight friction. The acetic and most other acids combine with the oxide of mercury, and precipitate it from its solution in the nitric acid. See SALT. When one part of native sulphuret of an- timony is triturated or accurately mixed with two parts of corrosive sublimate, and exposed to distillation, the chlorine combines with the antimony, and rises in the form of the com- pound called butter of antimony ; while the sulphur combines with the mercury, and forms cinnabar. If antimony be used instead of the sulphuret, the residue which rises last consists of running mercury, instead of cinnabar. Mercury, being habitually fluid, very rea- dily combines with most of the nu'tals, to HER 599 MET which it communicates more or less of its fusibility. When these metallic mixtures contain a sufficient quantity of mercury to render them soft at a mean temperature, they are called amalgams. It very readily combines with gold, silver, lead, tin, bismuth, and zinc; more difficultly with copper, arsenic, and antimony ; and scarcely at all with platina or iron : it does not unite with nickel, manganese, or cobalt ; and its action on tungsten and molybdena is not known. Looking-glasses are covered on the back surface with an amalgam of tin. See iUJ.VEUING. Some of the uses of mercury have already been mentioned in the present article. The amalgamation of the noble metals, water- gilding, the making of vermilion, the silver- ing of looking-glasses, the making of barome- ters and thermometers, and the preparation of several powerful medicines, are the principal uses to which this metal is applied. Scarcely any substance is so liable to adul- teration as mercury, owing to the property which it possesses of dissolving completely some of the baser metals. This union is so strong, that they even rise along with the quicksilver when distilled. The impurity of mercury is generally indicated by its dull as- pect; by its tarnishing, and becoming covered with a coat of oxide, on long exposure to the air; by its adhesion to the surface of glass; and, whan shaken with water in a bottle, by tilt- speedy formation of a black powder. Lead and tin are frequent impurities, and the mer- cury becomes capable of taking up more of these, if zinc or bismuth be previously added. In order to discover lead, the mercury may be agitated with a little water, in order to oxidize that metal. Pour off the water, and digest the mercury with a little acetic acid. This will dissolve the oxide of lead, which will be indicated by a blackish precipitate with sul- phuretted water. Or to this acetic solution add a little sulphate of soda, which will pre- cipitate a sulphate of lead, containing, when dry, 70 per cent, of metal. If only a very minute quantity of lead be present in a large quantity of mercury, it may be detected by solution in nitric acid, and the addition of sulphuretted water. A dark brown precipitate will ensue, and will subside if allowed to stand a few days. One part of lead may thus be separated from 15263 parts of mercury. Bis- muth is detected by pouring a nitric solu- tion, prepared without heat, into distilled water ; a white precipitate will appear if this metal be present. Tin is manifested, in like manner, by a weak solution of pitro-muriate of gold, which throws down a purple sedi- ment ; and zinc by exposing the metal to heat. The black oxide is rarely adulterated, as it would be difficult to find a substance well suited to this purpose. If well prepared, it may be totally volatilized by heat. The red oxide of mercury by nitric aeid is very liable to adulteration with red lead. It should be totally volatilized by heat. Red sulphurct of mercury is frequently adulterated with red lead ; which may be de- tected by heat Corrosive muriate of mercury. If there be any reason to suspect arsenic in this salt, the fraud may be discovered as follows : Dissolve a small quantity of the sublimate in distilled water ; add a solution of carbonate of am- monia till the precipitation ceases, and filter the solution. If, on the addition of a few drops of ammoniated copper to this solution, a precipitate of a yellowish-green colour be produced, the sublimate contains arsenic. Sub-muriate of mercury, or calomel, should be completely saturated with mercury. This may be ascertained by boiling, for a few mi- nutes, one part of calomel with a thirty-second part of muriate of ammonia in ten parts of distilled water. When carbonate of potash is added to the filtered solution, no precipitation will ensue, if the calomel be pure. This pre- paration, when rubbed in an earthen mortar with pure ammonia, should become intensely black, and should exhibit nothing of an orange hue. MESOLYTE. Needle-stone. MESOTYPE. Prismatic zeolite. This species of the genus zeolite is divided by Pro- fessor Jameson into three sub-species, the fibrous zeolite, natrolite, and mealy zeolite; which see. METALS. The most numerous class of undecompounded chemical bodies, distin- guished by the following general characters : 1. They possess a peculiar lustre, which continues in the streak, and in their smallest fragments. 2. They are fusible by heat ; and in fusion retain their lustre and opacity. 3. They are all, except selenium, excellent conductors both of electricity and caloric. 4. Many of them may be extended under the hammer, and are called malleable; or under the rolling press, and are called lam in- able ; or drawn into wire, and are called duc- tile. This capability of extension depends, in some measure, pn a tenacity peculiar to the metals, and which exists in the different spe- cies with very different degrees of force. See COHESION. 5. When their saline combinations arc elec- trized, the metals separate at the resino-electiic or negative pole. 6. When exposed to the action of oxygen, chlorine, or iodine, at an elevated temperature, they generally take fire, a id, combining with one or other of these three elementary dis- solvents in definite proportions, are converted iuto earthy or saline looking bodies, devoid of metallic lustre and ductility, called oxides, chlorides, or iodides. 7. They are capable of combining in their MET 600 MET melted state with each other, in almost every proportion, constituting the important order of metallic alloys ; in which the characteristic lustre and tenacity are preserved. See ALLOY. 8. From this brilliancy and opacity con- jointly, they reflect the greater part of the light which falls on their surface, and hence form excellent mirrors. 9. Most of them combine in definite pro- portions with sulphur and phosphorus, form- ing bodies frequently of a semi-metallic as- pect ; and others unite with hydrogen, carbon, and boron, giving rise to peculiar gaseous or solid compounds. 10. Many of the metals are capable of as- suming, by particular management, crystalline forms; which are, for the most part, either cubes or octohedrons. The relations of the metals to the various objects of chemistry, are so complex and di- versified, as to render their classification a task of peculiar difficulty. I have not seen any arrangement to which important objections may not be offered ; nor do I hope to present one which shall be exempt from criticism. The main purposes of a methodical distribution are to facilitate the acquirement, retention, and application of knowledge. With regard to metals in general, I conceive these purposes may be to a considerable extent attained, by beginning with those which are most eminently endowed with the characters of the genus, which most distinctly possess the properties that constitute their value in common life, and which caused the early inhabitants of the earth to give to the first metallurgists a place in mythology. Happy had their idolatry been always confined to such real benefactors ! Inventas aut qui vitam excoluere per artes, Quique sui memores, alios fecere merendo. By arranging metals according to the degree in which they possess the obvious qualities of unalterability, by common agents, tenacity, and lustre, we also conciliate their most im- portant chemical relations, namely, those to oxygen, chlorine, and iodine ; since their metallic pre-eminence is, popularly speaking, inversely as their affinities for these dissolvents. In a strictly scientific view, their habitudes with oxygen should perhaps be less regarded in their classification than with chlorine, for this element has the most energetic attraction for the metals. But, on the other hand, oxygen, which forms one-fifth of the atmospheric volume, and eight-ninths of the aqueous mass, operates to a much greater extent among metallic bodies, and incessantly modifies their form, both in nature and art. Now the order we propose to follow will indicate very nearly their relations to oxygen. As we progressively descend, the influence of that beautiful element progres- sively increases. Among the bodies near the head, its powers are subjugated by the metallic constitution ; but among those near the bot. torn, it exercises an almost despotic sway, which Volta's magical pile, directed by the genius of Davy, can only suspend for a season. The emancipated metal soon relapses under the dominion of oxygen. General Table of the Metals. NAMES. Sp. gr. Precipitants. Colour of Precipitates by Ferroprussiate of potash. nfusion of galls. Hydrosul- phurets. Sulphuretted hydrogen. 1 Platinum 2 Gold 21 .4T 19.30 Mur. ammou. ( Sulph. iron i Nitr. mercury Yellowish-whitt Green; met. Yellow Black met.powd. Yellow 3 Silver 10.45 Common salt White Yel.-Brown Black Black 4 Palladium 11.8 Prus. mercury Deep orange Blackish-brown Black-brown 5 Mercury 6 Copper 13.6 8.9 | Common salt } Heat Iron White passing \ to yellow ) led-brovvn Orange-yellow 3rown Brownish-black Black Black Do. 7 Iron 7.7 | Succincsoda \ with perox. Blue, or white passing to blue Protox. 1 Perox. b'.ack J Black 8 Tin 7.29 Cor. sublim. White ( Protox bLick 1 Perox. yejlow Brown 9 Lead 11.35 Sulph. soda Do. White Black Black 10 Nickel 11 Cadmium 8.4 8.6 Sulph. potash ? Zinc Do. Do. Grey-white Do. Orange-yellow Orange-vellow 12 Zinc 6.9 Alk. carbonate Do. White Yellowish-white 13 Bismuth 9-88 Water Do. Yellow Black-brown Black-brown 14 Antimony 6.70 f Water 1 Zinc With dilute so- lutions white White from | water j Orange Orange 10 Manganese 8. Tartr. pot. White ' White Milkiness 16 Cobalt 8.6 Alk. carbonate Brown-yellow Yellow-white Black 17 Tellurium 0.115 ( Water | \ Antimony j Yellow Blackish 18 Arsenic 1 8 35? 1 5.70? Nitr. lead White Yellow Yellow 19 Chromium 20 Molybdrnun 6.90 8.6 no. Do.? Green Brown Brown Deep brown Green Brown MET 601 MET NAMES. Sp. gr. Precipitant! . Colour of Precipitates by Ferroprussiate of potash. Infusion of galls. Hydrosul- phurets. Sulphuretted hydrogen. 21 Tungsten 22 Columbium 17.4 5.6? Dilute acids Zincorinf.galls Olive Orange Chocolate 23 Selenium 4.3? ( Iron I Sulphite amm. 24 Osmium 25 Rhodium ? 10.65 Mercury Zinc? ( Purple passing \ to deep blue o 26 Iridium 18.68 Do.? o 27 Uranium 28 Titanium 29 Cerium 9.0 ? ? Ferrop. pot. Inf. galls. Oxal. ainm. Brown-red Grass-green Milk-white Chocolate Red-brown Brown-yellow Grass-green White 30 Potassium 0.865 I Mur. plat. | 1 Tart, acid ) 31 Sodium 0.972 32 Lithium 33 Calcium 34 Barium 35 Strontium 36 Magnesium 37 Yttrium 38 Glucinum 39 Aluminum 40 Zirconium 41 Silioium The first 12 are malleable ; and so are the 30th, 31st, and 32d in their congealed state. The first 1C yield oxides, which are neutral &alifiable bases. The metals 17, 18, 19, 20, 21, 22, and 23, are acidifiable by combination with oxygen. Of the oxides of the rest, up to the 30th, little is known. The remaining metals form, with oxygen, the alkaline and earthy bases. The order of their affinity for oxygen, as far as it has been ascertained, is stated in the table of Elective A-RTRACTION of oxygen and the metals. We shall now give an example of the method of analyzing a metallic alloy, of silver, copper, lead, bismuth, and tin. Let it be dissolved, with the aid of heat, in an excess of nitric acid, sp. gr. 1.23. Evaporate the solution almost to dryness, and pour water on the residuum. We shall thus obtain a solution of the nitrates of silver, copper, and lead, while the oxides of tin and bismuth will be left at the bottom. By ex- posing the latter mixture to the action of nitric acid, the oxide of bismuth will be separated from that of tin. To determine the proportions of the other metals, we pour first into the hot and pretty dilute solution, muriatic acid, which will throw down the silver. After filtration, we add sulphate of soda, to separate the lead ; and finally, carbonate of potash to precipitate the zinc. The quantity of each metal may now be deduced from the weight of each pre- cipitate, according to its specific nature, agree- ably to the principles of composition given under the individual metals. See ORES (Ana- lysis of). METEORITES, OR METEORIC STONES, are peculiar solid compounds of earthy and metallic matters, of singular aspect and composition, which occasionally descend from the atmosphere, usually from the bosom of a luminous meteor. This phenomenon affords an instructive example of the triumph of human testimony over philosophical scep- ticism. The chronicles of almost every age had recorded the fall of ponderous stony or earthy masses from the air, but the evidence had been rejected by historians, because the phenomenon was not within the range of their philosophy. At length the sober and solid researches of physical science put to shame the incredulity of the metaphysical school. M. Abel Remusat shows in his translation recently made of the work of Ma- Touan-Lin, a Chinese author of the 13th century, that the Chinese and Japanese noted with much pre- cision every thing connected with the appear- ance of these singular phenomena. They re- marked that the stones fell sometimes in per- fectly serene weather ; they compared the ex- plosions which took place to thunder, to the noise of a tumbling wall, to the bellowing of an ox. The hissing which accompanies their fall was likened to the sounding of the wings of birds of prey, or of cloth torn asunder. According to them, the stones are always burn- ing hot at the moment when they reach the ground ; their outward surface is black ; some of them ring when struck, like metallic bodies. The name which they give them means, fall* ing stars changed into stones. The Chinese believed that the appearances of aerolites were connected with contemporary events; for which reason they formed cata- logues of them ! We have little reason to laugh at this Oriental prejudice. Were the philosophers of Europe wiser, when resisting the evidence of facts, they affirmed that the falls of stones from the atmosphere were im- possible ? The Academy of Sciences declared in 1769, that a stone picked up at the instant MET 602 MET of its fall, near Luce, by several persons, u>ho had followed its descent with their eyes to the spot where it struck the ground, did not fall from the sky. Finally, the proces-veroal of the municipality of Lagrange de Juliac, af- firming that on the 30th Aug. 1790, there fell in the fields, on the roofs of houses, in the streetvS of the village, a great quantity of stones, was treated in the journals of the time as a ridiculous tale, made to excite the PITY not only of men of learning, but of all rational Icings. " Philosophers," says Chladni, " who will not admit facts which they cannot ex- plain, injure the advancement of science, as much as those to whom too great credulity may be reproached." " While all Europe," says the celebrated Vauquelin, "resounded with the rumour of stones fallen from the heavens ; and while phi- losophers, distracted in opinion, were framing hypotheses to explain their origin, each accord- ing to his own fancy, the Hon. Mr. Howard, an able English chemist, was pursuing in silence the only route which could lead to a solution of the problem. He collected spe- cimens of stones which had fallen at different times, procured as much information as pos- sible respecting them, compared the physical or exterior characters of these bodies; and even did more, in subjecting them to chemical analysis, by means as ingenious as exact. " It results from his researches, that the stones which fell in England, in Italy, in Ger- many, in the East Indies, and in other places, have all such a perfect resemblance, that it is almost impossible to distinguish them from each other; and what renders the similitude more perfect and more striking is, that they are composed of the same principles, and nearly in the same proportions." I have given this just and handsome tribute to English genius in the form of a quotation from the French chemist; by appropriating the language to one's self, as has been prac- tised in a recent compilation, the force of the compliment is in a great measure done away. " I should have abstained," continues M. Vauquelin, " from any public notice of an object, which has been treated of in so able a manner by the English chemist, if he himself had not induced me to do so, during his re- sidence in Paris ; had not the stones which I analysed been from another country ; and had not the interest excited by the subject rendered this repetition excusable. *' It is therefore to gratify Mr. Howard ; to give, if possible, more weight to his experi- ments; and to enable philosophers to place full confidence in them, rather than to offer any thing new, that I publish this memoir." Journal des Mines, No. 76; and Tilloch's Mag. vol. xv. p. 346. It is remarkable, that all the stones, at whatever period, or in whatever part of the world they may have fallen, have appeared, as far as they have been examined, to consist of the same substances ; and to have nothing similar to them, not only among the minerals in the neighbourhood of the places where they were found, but among all that have hitherto been discovered in our earth, as far as men have been able to penetrate. For the chemical analysis of a considerable number of specimens we are particularly indebted to Mr. Howard, as well as to Klaproth and Vauquelin, and a precise mineralogical description of them has been given by the Count de Bournon and others. They are all covered with a thin crust of a deep black colour, they are without gloss, and their surface is roughened with small asperities. Internally they are grayish, and of a granu- lated texture, more or less fine. Four different substances are interspersed among their tex- ture, easily distinguished by a lens. The most abundant is from the size of a pin's head to that of a pea, opaque, with a little lustre like that of enamel, of a gray colour sometimes in- clined to brown, and hard enough to give faint sparks with steel. Another is a martial pyrites, of a reddish-yellow colour, black when pow- dered, not very firm in its texture, and not at- tractible by the magnet. A third consists of small particles of iron in a perfectly metallic state, which give to the mass the quality of being attracted by the magnet, though in some specimens they do not exceed two per cent, of the whole weight, while in others they extend to a fourth. These are connected together by a fourth of an earthy consistence in most, so that they may be broken to pieces by the fingers with more or less difficulty. The black crust is hard enough to emit sparks with steel, but may be broken by a stroke with a hammer, and appears to possess the properties of the very attractible black oxide of iron. Their specific gravity varies from 3-352 to 4-281. The crust appears to contain nickel united with iron, but Mr. Hatchett could not deter- mine its proportion. The pyrites he estimates at iron -68, sulphur -13, nickel -06, extraneous earthy matter -13. In the metallic particles disseminated through the mass, the nickel was in the proportion of one part, or thereabout, to three of iron. The hard separate bodies gave silex -50, magnesia -15., oxide of iron -34, oxide of nickel -025 ; and the cement, or ma- trix, silex -48, magnesia -18, oxide of iron -34, oxide of nickel -025. The increase of weight in both these arose from the higher oxidation of the iron. These proportions are taken from the stones that fell at Benares on the 19th of December, 1798. M. G. Rose of Berlin has succeeded in sepa- rating crystals of pyroxene from a large spe- cimen of the aerolite of Juvenas, and has mea- sured the angles with the reflective goniometer ; one of the crystals is of the octahedral variety, represented in the 109th figure of Haiiy's Mi- neralogy. The same rocky tissue contains microscope hemitrope crystals, which appear MET 603 MET to be felspar, with a base of soda, i. e. albite. In the aerolite of Pallas the olivine is perfectly crystallized. The solitary masses of native iron that have been found in Siberia, Bohemia, Senegal, and South America, likewise agree in the circum- stance of being an alloy of iron and nickel ; and are either of a cellular texture, or have earthy matter disseminated among the metal. Hence, a similar origin has been ascribed to them. Laugier, and afterward Thenard, found chrome likewise, in the proportion of about one per cent., in different meteoric stones they examined. In all the instances in which these stones have been supposed to fall from the clouds, and of which any perfect account has been given, the appearance of a luminous meteor, exploding with loud noise, has immediately preceded, and hence has been looked to as the cause. The stones likewise have been more or less hot, when found immediately after their supposed fall. Different opinions, however, have been entertained on this subject, which is certainly involved in much difficulty. Some have supposed them to be merely projected from volcanoes ; while others have suggested, that they might be thrown from the moon; or be bodies wandering through space, and at length brought within the sphere of attraction of our planet. Various lists of the periods, places, and ap- pearances of these showers of stony and earthy matters, have been given from time to time in the scientific journals. The latest and most complete is that published in the 1st vol. of the Ed. Phil. Journ. compiled partly from a printed list by Chladni, and partly from a manuscript one of Mr. Allan, read some years ago at the Royal Society of Edinburgh. It appears that Domenico Troili, a Jesuit, pub- lished at Modena, in 1766, a work entitled, Delia Caduta di un Sasso dull Aria, ragiona- mento, in which the ingenious author proves, in the clearest manner, both from ancient and modern history, that stones had repeatedly fallen from the heavens. This curious disser- tation (ragionamcnto) is in the possession of Mr. Allan. The compiler of the new list justly observes, that nothing can show more strikingly the universality and obstinacy of that scepticism which discredits every thing that it cannot understand, than the circumstance that his work should have produced so little effect, and that the numerous falls of meteoric stones should have no long been ranked among the inventions of ignorant credulity. Mr. Howard's admirable dissertation was published in the Phil. Trans, for 1802. It is reprinted in the 13th vol. of Tilloch's Maga- zine, and ought to be studied as a pattern of scientific research. The following Table is copied from the 31st vol. of the Ann. de C/iimic: CHRONOLOGICAL LIST OF METEORIC STONES. Sect. I Before the Christian Era. Division I. Containing those which can be referred pretty nearly to a date. A. C. 1478. The thunderstone in Crete, mentioned by Malchus, and regarded probably as the symbol of Cybele Chronicle of Paros % 1. 18, 19. 1451. Shower of stones which destroyed the enemies of Joshua at Beth-horon, was pro- bably hail. Joshua, chap. x. 11. 1200. Stones preserved at Orchomenos. Pausanias. 1168. A mass of iron upon Mount Ida in Crete. Chronicle of Paros, 1. 22. 705 or 704. The Ancyle or sacred shield, which fell in the reign of Numa. It had nearly the same shape as those which fell at the Cape and at A gram. Plutarch, in Num. 654. Stones which fell upon Mount Alba in the reign of Tullus Hostilius. " Crelri cecidere coclo lapides." Liv. 1. 30. 644. Five stones which fell in China, in the country of Song De Guignes. 465. A large stone at yEgospotamos, which Anaxagoras supposed to come from the sun. It was as large as a cart, and of a burnt colour. " Qui lapis etiam mine ostenditur, magnitudinc velds, colore adusto." Plu- tarch, Pliny, lib. ii. cap. 58. 465. A stone near Thebes Scholiast of Pindar. 211. Stones fell in China along with a fall- ing star De Guigncs, &c. 205 or 206. Fiery stones Plutarch. Fab. Max. cap. 2. 192. Stone fell in China. De Guignes. 176. A stone fell in the Lake of Mars " Lapidem in Agro Crustumino in Lacum Martis de ccclo cecidisse." Liv. xli. 3. 90 or 89. " Eodem causam dicente, later ibus coctis pluisse, in cjus anni acta relatum est."Plin. Nat. Hist. lib. ii. cap. 56. 89. Two large stones fell at Yong in China. The sound was heard over 40 leagues. De Guigncs. 56 or 52. Spongy iron fell in Lucania Plin. 46. Stones fell at Acilla Caesar. 38. Six stones fell in Leang in China. De Guignes. 29. Four stones fell at Po in China De Guignes. 22. Eight stones fell from heaven, in China. De Guignes. 12. A stone fell at Ton-Kouan De Guigncs. 9. Two stones fell in China De Guigncs. 6. Sixteen stones fell in Ning-Tcheon, and other two in the same year. De Girignes. MET 604 MET Division II. Containing those of which the date cannot be determined. The mother of the Gods, which fell at Pes- sinus. The stone preserved at Abydos. Plin. The stone preserved at Cassandria. Plin. The Black stone, and also another preserved in the Caaba of Mecca. The " Thunderbolt, black in appearance like a hard rock, brilliant and sparkling," of which the blacksmith forged the sword of Antar. See Quarterly Review, vol. xxi. p. 225. and Antar, translated by T. Ha- . milton, Esq. p. 152. The stone preserved in the Coronation Chair of the Kings of England was not meteoric. Sect. 2. After the Christian Era. P. C. In the years, 2, 106, 154, 310, and 333, stones fell in China. Abel Remusat. Journ. de Physique, May, 1819. A stone in the country of the Vocontini. Plin. 452. Three large stones fell in Thrace. Cedrenus and Marcelling Chronicon. p. 29. " Hoc tempore" says Marcellinus, " ires inagni lapides e ccclo in Thracia cecide- runt." Sixth Century. Stones fell upon Mount Lebanon, and near Emisa in Syria. Damascius. About 570. Stones near Bender in Arabia. Alkoran, viii. 16. and cv. 3. and 4. 648. A fiery stone at Constantinople. Several Chronicles. 823. A shower of pebbles in Saxony. 839. Stones fell in Japan. AM Remusat. 852. A stone fell in Tabaristan, in July or August. De Sacy and Quatremere. 856. In December, five stones fell in Egypt. The same. 885. Stones fell in Japan. Abel Remusat. 897. A stone fell at Ahmedabad. Quatre- mere. In 892, according to the Chron. Syr. 92 1 . Great stones fell at Narni. Benedictus de Saint- Andrea, in the library of prince Chigi at Rome. 951. A stone fell near Augsburg. Alb. Stud, and others. 998. Two stones fell, one near the Elbe, and the other in the town of Magdeburg. Cosmos and Spangenberg. 1009. A mass of iron fell in Djordjan. Avicenna. 1021. Stones fell in Africa between the 24th July and the 21st of August. De Sacy. 1112. Stones or iron fell near Aquileja. Valvasor. 1135 or 1136. A stone fell at Oldisleben in Thuringia. Spangenberg, and others. 1164. During Pentecost, iron fell in Mis- nia. Fabricius. 1249. Stones fell at Quedlinbourg, Ballen- stadt, and Blackenburg, on the 26th July. Spangenberg and Rivander. Thirteenth Century. A stone fell at Wurz- burg. Schottus, Phys- Cur. Between 1251 and 1363. Stones fell at Welikoi-Ustiug in Russia. Gilbert' s An- nal. torn. 35. 1280. A stone fell at Alexandria in Egypt. De Sacy. 1300 nearly. Great stones fell in Aragon. Manuscript chronicle in the national mu- seum of Pest in Hungary. 1304, Oct. 1. Stones fell at Friedland or Fried- berg. Kranx and Spangenberg. 1305. Stones fell in the country of the Van- dais. 1328, Jan. 9. In Mortahiah and Dakhaliah. Quatremere. 1368. A mass of iron in the Duchy of Olden- burg. Siebrand, Meyer. 1379, May 26. Stones fell at Minden in Hanover Lerbeci us . 1421. A stone fell in the island of Java. Sir T. S. Raffles. 1438. A shower of spongy stones at Roa, near Burgos in Spain. Proust. A stone fell near Lucerne. Cysat. 1474. Two great stones fell near Viterbo. Bibliotcca Italiana, Sept. 1820. 1491, March 22. A stone fell near Crema. Simoncta. 1492, Nov. 7- A stone of 2601b. fell at Ensisheim near Sturgau, in Alsace. It is now in the library of Colmar, and has been reduced to 15t)lb. Trithemius, Hirsaug. Annal. Conrad Gesner, Liber de Rerum Fossilium Figuris, cap. 3. p. 66. in his Opera, Zurich, 1565. 1496, Jan. 26. or 28. Three stones fell be- tween Cesena arid Bertonori. Buriel and Sabellicus. 1511, Sept. 4. Several stones, some of which weighed lllb. and others 81b. fell at Crema. Giovanni del Prato, and others. 1520, May. Stones fell in Aragon. Diego de Sayas. 1540, April 28. A stone fell in the Limousin. Bonav. de St. Amable. ? Between 1540 and 1550. A mass of iron fell in the forest of Naunhoff. Chronicle of the Mines of Misnia. Iron fell in Piedmont Mercati and Scaliger. 1548, Nov. 6. A black mass fell at Mans- feld in Thuringia. 'Bonav. de St. Amable. 1552, May 19. Stones fell in Thuringia near Schlossingen. Spangenberg. 1559. Two large stones, as large as a man's head, fell at Miscolz in Hungary, which are said to be preserved in the treasury at Vienna. Sthuanfi. 1561, May 17. A stone called the Arx Julia fell at Torgau and Eilenborg. Gesner and De Boot. MET 605 MET 1580, May 27- Stones fell near Gottingen. -- Bangs. 1581, July 26. A stone, 39lb. weight, fell in Thuringia. It was so hot that no per- son could touch it. Binhard, Olearius. 1T>83, Jan. 9. Stones fell at Castrovillari. Casto, Mercati, and Imperati. IMarch 2. A stone fell in Piedmont of the size of a grenade. ' 1591, June 19. Some large stones fell at I^unnersdorf. Lucas. 1596, March 1. Stones fell at Crevalcore. MUtarelU. In the Sixteenth Century, not in 1603. A stone fell in the kingdom of Valencia. Ceesius and the Jesuits of Coimbra. 1618, August. A great fall of stones took place in Styria. Hammer. A metallic mass fell in Bohemia. Kronland. 1621, April 17. A mass of iron fell about 100 miles S. E. of Lahore. Jehan Guir's Memoirs. 1622, Jan. 10. A stone fell in Devonshire. Rumph. 1628, April 9. Stones fell near Hatford in Berkshire; one of them weighed 241b. Gent. Mag. Dec. 1796. 1634, Oct. 27. S'tones fell in Charollois. Morinus. 1635, June 21. A stone fell at Vago in Italy.? July 7 or Sept. 29. A stone, weighing about 11 oz. fell at Calce. Valisnieri, Opere, vi. 64. ? 1636, March 6. A burnt-looking stone fell between Sagan and Dubrow in Silesia. Lucas and Cluverius. 1637, Nov. 29. Gassendi says, a stone of a black metallic colour fell on Mount Vaision, between Guillaume and Perne in Provence. It weighed 54 Ib. and had the size and shape of the human head. Its specific gravity was 3.5. Gassendi, Opera, p. 96. Lyons, 1658. 1642, August 4. A stone weighing 41b. fell between Woodbridge and Aldborough in Suffolk. Gent. Mag. Dec. 1?96. 1643, or 1644. Stones fell in the sea. Wurfbain. 1647, Feb. 18. A stone fell near Zwicau. Schmid. August. Stones fell in the bailliage of Stolzenem in Westphalia. Gilbert's An- nal. Between 1647 and 1654. A mass fell in the sea. Willman. 1650, August 6. A stone fell at Dordrecht. Senguerd. 1654, March 30. Stones fell in the island of Funen. Bariholinus. A large stone fell at Warsaw. Petr. Borel- lus. A small stone fell at Milan^ and killed a Franciscan. Museum Septaiianum. 1668, June 19 or 21. Two stones, one 3001b. and the other 2001b. weight, fell near Ve- rona. Legallois, Conversations, &c. Paris, 1672. Valisnieri, Opere, ii. p. 64. 66. Montanan and Francisco Carli, who pub- lished a letter, containing several curious notices respecting the fall of stones from the heavens. 1671, Feb. 27- Stones fell in Suabia Gilberts Annal. torn, xxxiii. 1674, Oct. 6. Two large stones fell near Glaris. Scheuchzer. Between 1675 and 1677? a stone fell into a fishing-boat near Copinshaw. Wallace's Account of Orkney, and Gent. Mag. July, 1806. 1677? May 28. Several stones, which pro- bably contained copper, fell at Ermundorf near Roosenhaven Misc. Nat. Cur. 1677- App. 1680, May 18. Stones fell at London. King. 1697, Jan. 13. Stones fell at Pentolina near Sienna. Soldani after Gabrieli. 1698, May 19. A stone fell at Waltring. Scheuchzer. 1706, June 7. A stone of 72lb. fell at La- rissa in Macedonia. It smelt of sulphur, and was like the scum of iron. Paul Lucas. 1715, April 11. Stones fell not far from Stargard in Pomerania. Ann. de Gilbert, Ixxi. p. 215. 1722, June 5. Stones fell near Scheftlar in Freisingen Meich elbeck. 1723, June 22. About 33 stones, black and metallic, fell near Plescowitz in Bohemia. Rost and Stepling. 1727, July 22. Stones feU at Liboschitz in Bohemia. Stepling. 1738, August 18. Stones fell near Carpen- tras. Castillon. 1740, Oct. 25. Stones fell at Rasgrad. Gilbert's Annal. torn. 1. to 1741. A large stone fell in winter in Greenland Egede. 1743. Stones fell at Liboschitz in Bohemia. Stepling. ? 1750, Oct. 1. A large stone fell at Niort near Coutance Huard and Lalande. 1751, May 26. Two masses of iron of 7llb. and 161b. fell in the district of Agram, the capital of Croatia. The largest of these is now in Vienna. 1753, July 3. Four stones, one of which weighed 13lb. fell at Strkow, near Tabor. Stepling, u De Pluvia Lapidea, anni 1753, ad Strkow, et ejus causis, mcditatio," p. 4 Prag. 1754. Sept. Two stones, one of 20lb. and the other of 1 lib. fell near the villages of Laponas and Pin- in Beme. Lalande and Richard. 1755, July. A stone fell in Calabria, at Terranuova, which weighed 71b. 7oz. Domin. Tata. 1766, end of July. A stone fell at Alboreto in Moclena Troili. MET 606 MET 1766, August 15. A stone fell at Noyellara. Troili. ? 1768, Sept. 13. A stone fell near Luce in Maine. It was analyzed by Lavoisier, &c. Mem. A cad. Par. A stone fell at Aire. Mem. Acad. Par. Nov. 20. A stone, weighing 381b. fell at Mauerkirchen in Bavaria. Imhof. 1773, Nov. 17. A stone, weighing 9lb. loz. fell at Sena in Aragon Proust. 1775, Sept. 19. Stones fell near Rodach in Cobourg. Gilbert's Annal. torn, xxiii. or 1776. Stones fell at Obruteza in Volhynia. Gilberfs Annal. torn. xxxi. 1776 or 1777, Jan. or Feb. Stones fell near Fabriano. Soldani and Amoretti. 1779. Two stones, weighing 3foz. each, fell at Pettiswoode in Ireland. Bingley, in Gent. Mag. Sept. 1796. 1780, April 1. Stones fell near Beeston in England. Evening Post. About 1780. Masses of iron fell in the terri- tory of Kinsdale, between West-River mountain and Connecticut. Quarterly Review, No. 59, April, 1824. 1782. A stone fell near Turin. Tata and Amoretti. 1785, Feb. 19. Stones fell at Eichstadt. Pickel and Stuz. 1787, Oct. 1. Stones fell in the province of Charkow, in Russia Gilbert's Annal. torn. xxxi. 1790, July 24. A great shower of stones fell at Barbotan near Roquefort, in the vicinity of Bourdeaux. A mass, 15 inches in dia- meter, penetrated a hut, and killed a herds- man and a bullock. Some of the stones weighed 25lb. and others 301b Lomet. 1791, May 17. Stones fell at Cassel-Ber- ardenga, in Tuscany. Soldani. Oct. 20. Stones fell at Menabilly, in Comwallis. King. 1794, June 16. Twelve stones, one of which weighed 7-g-oz. fell at Sienna. Howard and Klaproth have analyzed these stones Phil. Trans. 1794, p. 103. 1795, April 13. Stones fell at Ceylon. Beck. Dec. 13. A large stone, weighing 55lb. fell near Wold Cottage in Yorkshire. No light accompanied the fall Gent. Mag. 1796. 1796, Jan. 4. Stones fell near Belaja-Zerkwa in Russia. Gilbert's Annal. torn. xxxv. Feb. 19. A stone of lOlb. fell in Por- tugal. Southey's Letters from Spain. 1798, March 8. or 12. Stones, one of which was the size of a calf's head, fell at Sales. Marquis de Dr6c. Dec. 19. Stones fell in Bsngal. Howard, Lord Vakntia. 1801. Stones fell on the island of Tonne- liers. Bory de St. Fincent. 1802, Sept. Stones fell in Scotland ? Month- ly Magazine, Oct. 1802. 1803, April 26. A great fall of stones took place at Aigle. They were about three thousand in number, and the largest weighed about l?lb. - July 4. Stones fell at East Norton. Phil. Mag. and Bill. Brit. - Oct. 8. A stone fell near Apt. -- Dec. 13. A stone fell near Eggen- felde in Bavaria, weighing S^lb. Imhof. 1804, April 5. A stone fell at Fossil, near Glasgow. Phil. Mag. -- 1807. A stone fell at Dordrecht. Van Beck Calkoen. 1805, March 25. Stones fell at Doroninsk in Siberia. Gilberfs Annal. torn. xxix. and xxxi. - June. Stones, covered with a black crust, fell in Constantinople. Kengat Ingigian. 1806, March 15. Two stones fell at St. Etienne and Valence ; one of them weighed 81b. - May 17. A stone, weighing 2-|lb. fell near Basingstoke in Hampshire. Monthly Magazine. 1807, March 13. (June 17. according to Lucas). A stone of 1601b. fell at Timochin, in the province of Smolensko in Russia Gilbert's Annal. - Dec. 14. A great shower of stone fell near Weston in Connecticut. Masses of 20lb.25lb. and351b. were found Silliman and Kingsley. 1808, April 19. Stones fell at Borgo San- Donino. Guidotti and Sgagnoni. - May 22. Stones weighing 41b. or 51b. fell near Stannern in Moravia Bibl. Brit. - Sept. 3. Stones fell at Lissa in Bo- hemia. De Schreibers. 1809, June 17- A stone of 6oz. fell on board an American vessel, in latitude 30 58 N., and longitude 70 25' W Bibl. Brit. ? 1810, Jan. 30. Stones, some of which weighed about 21b. fell in Caswell county, North America. Phil. Mag. vol. xxxvi. - July. A great stone fell at Shahabad in India. It burned five villages, and killed several men and women. Phil. Mag. xxxvii. p. 236. - Aug. 10. A stone weighing 7flb. fell in the county of Tipperary in Ireland. Phil. Mag. vol. xxxviii. Mr. W. Higgins published an analysis of it. - Nov. 23. Stones fell at Mortelle, Ville- rai, and Moulinbrul, in the department of the Loiret; one of them weighed 40lb. and the other 20lb. Nich. Journal, vol. xxxix. p. 158. 1811, March 12. or 13. A stone of 15lb. fell in the province of Poltawa in Russia. Gilberfs Annals, xxxviii. July 8. Stones, one of which weighed fell near Berlanguillas in Spain. Bibl. Brit. torn, xlviii. p. 162. MET 607 MET 1812, April 10. A shower of stones fell near Thoulouse. - April 15. A stone, the size of a child's head, fell at Erxleben. A specimen of it is in the possession of Professor Hauss- man of Brunswick. Gilbert's Annal. xl. and xli. Aug. 5. Stones fell at Chantonay. Brochant. 1813, March 14. Stones fell at Cutro in Calabria, during a great fall of red dust. Bill. Brit. Oct. 1813. Sept. 10. Several stones, one of which weighed 171b. fell near Limerick in Ireland. Phil. Mag. 1814, Feb. 3. A stone fell near Bacharut in Russia. Gilbert's Annal. torn. 1. Sept. 5. Stones, some of which weighed 18lb. fell in the vicinity of Agen. Phil. Mag. vol. xlv. . Nov. 5. Stones, of which 19 were found, fell in the Doab in India. Phil. Mag. 1815, Feb. 18. A stone fell at Duralla in India Phil. Mag. Journal of Science. Oct. 3. A large stone fell at Chassigny near Langres. Pistolkt. Ann. de Chim. 1816, A stone fell at Glastonbury in Somer- setshire. Phil. Mag. 1817, May 2. and 3. There is reason to think, that masses of stone fell in the Baltic after the great meteor of Gottenburg. Chladni. ? 1818, Feb. 15. A great stone appears to have fallen at Limoge, but it has not been disinterred. Gazette de France, Feb. 25, 1818. March 30. A stone fell near Zuborzyca in Volhynia (analyzed by M. Laugier, Ann. de Museum, 17th year, 2d number). July 29. O. S. A stone of 71b. fell at the village of Slobodka in Smolensko. It penetrated nearly 16 inches into the ground. It had a brown crust with metallic spots. 1819, June 13. Stones fell at Jonzac, depart- ment of the lower Charente. These stones contain no nickel. Oct. 13. Stones fell near Politz, not far from Gera or Kostritz, in the princi- pality of Reuss. Gilbert's Annals, Ixiii. 1820, 21 to 22 March. A stone fell in the night at Vedenburgh in Hungary Hes- perus, xxvii. cah. 3. ' . . July 12. A stone fell near Likna, in the circle of Dunaborg, province ofWitepsk in Russia. Th. Grotthus. Ann. de Gilbert, Ixviii. 1821, June 15. Stones fell near Juvenas, containing no nickel. 1822, June 3. A stone fell at Angers. Ann. de Chim. Sept. 10. Sweden. 13. - near Carlstadt in near la Baffe, can- ton of Epinal, department of Vosges. Ann. de Chim. 1823, Aug. 7- near Nobleboro ia America. Silliman's American Journal, vii. 1824, towards the end of January. Many stones fell near Arenazzo, in the territory of Bologna. One of them weighing 12 Ibs. is preserved in the Observatory of Bologna. Diario di Roma. ' beginning of February. A great stone fell in the province of Irkutsk in Siberia. Some journals. Oct. 14. A stone fell near Zebrak, circle of Beraum, in Bohemia. The stone is preserved in the national museum of Prague. LIST OF MASSES OF IRON SUPPOSED TO HAVE FALLEN FROM THE HEAVENS. Sect. 1. Spongy or Cellular Masses containing Nickel. 1. The mass found by Pallas in Siberia, to which the Tartars ascribe a meteoric origin. Voyages de Pallas, torn. iv. p. 545. Paris, 1793. 2. A fragment found between Eibenstock and Johanngeorgenstadt. 3. A fragment probably from Norway, and in the imperial cabinet of Vienna. 4. A small mass weighing some pounds, and now at Gotha. 5. Two masses in Greenland, out of which the knives of the Esquimaux were made See Ross's Account of an Expedition to the Arctic Regions. Sect. 2. Solid Masses where the Iron exiatt in Rhomboids or Octahedrons, composed of Strata, and containing Nickel. 1. The only fall of iron of this kind, is that which took place at A gram, in 1751. 2. A mass of the same kind has been found on the right bank of the Senegal. Com- pagnon, Forster, Goldlerry. 3. At the Cape of Good Hope; Stromeyer has lately detected cobalt in this mass. Van Marum and Dankelman ; Branded Journal, vol. vi. 162. 4. In different parts of Mexico. Sonne- schmidt, Humboldt, and the Gazette de Mexico, torn. i. and v. 5. In the province of Bahia in Brazil. It is seven feet long, four feet wide, aad two feet thick, and its weight about 14,000 Ib JlfornaT/and Wollaston,- Phil. Trans. 1816, p. 270, 281. 6. In the jurisdiction of San Jago del Estera. Rubin de Ccelis, in the Phil. Trans. 1788, vol. Ixxviii p. 37. 7- At Elbogen in Bohemia. Gilbert's Annal. xlii. and xliv. 8. Near Lenarto in Hungary. Ditto, xlix. The origin of the following masses seems to be uncertain, as they do not contain nickel, and have a different texture from the pre- ceding : MIA 608 MIE 1. A mass found near the Red River, and sent from New Orleans to New York. Journ. des Mines, 1812, Bruce's Journ. 2. A mass at Aix-la-Chapelle containing arsenic. Gilbert's Annul, xlviii. 3. A mass found on the hill of Brianza in the Milanese. Chladni in Gilberts Annal. 1. p. 275. 4. A mass found at Grosltamdorf, and con- taining, according to Klaproth, a little lead and copper. Nickel or chromium is found to be the constant associate of the iron in the meteoro- lites. They are characteristic of meteoric iron, and are never found in mineral native iron. Nickel has been hitherto regarded as the sole characteristic ingredient of meteoric stones, but from the analyses of some late meteoro- lites it would appear, that this metal is occa- sionally absent, while chromium is always found. Hence the latter has come to be viewed as the constant characteristic. For a list of meteoric falls of dust, and soft substances, dry or moist, see CHLADNI in Ann. de Chim. et Phys. xxxi. 263. The phenomenon of red snow observed at Baffin's Bay has of late excited some specu- lation, being supposed to be a meteoric pheno- menon. But Mr. Bauer has proved by micro- scopic examination, that the colouring particles consist of a new species of the uredo, which grows upon the snow, to which he has given the appropriate name of uredo nivalis. He found the real diameter of an individual full grown globule of this fungus, to be the one thousand six hundredth part of an inch. Hence, in order to cover a single square inch, two million five hundred and sixty thousand of them are necessary. Journal of Science, vol. vii. p. 222. METEOROLOGY. See CLIMATE, DEW, RAIN. MIASCITE. A columnar variety of bitterspar, intermixed with asbestos, from Miaska in Siberia. MIASMATA. Vapours or effluvia, which, by their application to the human system, are capable of exciting various diseases, of which the principal are intermittent, remittent, and yellow fevers, dysentery and typhus. That of the last is generated in the human body itself, and is sometimes called the typhoid fomes. The other miasmata are produced from moist vegetable matter, in some unknown state of decomposition. The contagious virus of the plague, small-pox, measles, chincough, cynanche maligna, and scarlet fever, as well as of typhus and the jail fever, operates to a much more limited distance through the inter- medium of the atmosphere than the marsh miasmata. Contact of a diseased person is said to be necessary for the communication of plague ; and approach within 2 or 3 yards of him for that of typhus. The Walcheren miasmata extended their pestilential influence to vessels riding, at anchor, fully a quarter of a mile from the shore. The chemical nature of all these poisonous effluvia is little understood. They undoubt- edly consist, however, of hydrogen united with sulphur, phosphorus, carbon, and azote, in unknown proportions, and unknown states of combination. The proper neutralizers or destroyers of these gasiform poisons are nitric acid vapour, muriatic acid gas, and chlorine. The last two are the most efficacious; but require to be used in situations from which the patients can be removed at the time of the application. Nitric acid vapour may, how- ever, be diffused in the apartments of the sick, without much inconvenience. Bed-clothes, particularly blankets, can retain the contagious fomes, in an active state, for almost any length of time. Hence, they ought to be fumigated with peculiar care. The vapour of burning sulphur or sulphurous acid is used in the East, against the plague. It is much inferior in power to the other antiloimic reagents. See FUMIGATION and CHLORIDE OF (LIME) at the end. MICA. Professor Jameson subdivides this mineral species into ten sub-species, viz. mica, pinite, lepidolite, chlorite, green earth, talc, nacrite, potstone, steatite, and figure-stone. Mica. Colours yellowish and greenish- gray. Massive, disseminated, and crystal- lized. Its primitive figure is a rhomboid. The secondary forms are ; an equiangular six- sided prism, or table ; a rectangular four- sided prism, or table ; and a six-sided pyramid. Lateral planes smooth and splendent ; terminal, longitudinally streaked. Lustre pearly, or semi-metallic. Cleavage single. Fragments tabular and splintery. Translucent. Sectile. Streak gray-coloured. Harder than gypsum, but not so haid as calcareous spar. Feels meagre or smooth. Elastic-flexible. Sp. gr. 2.65. Before the blowpipe it melts into a grayish-white enamel. Its constituents are, silica 47, alumina 22, oxide of iron 15.5, oxide of manganese 1-75, potash 14.5 Klaproth. It occurs along with felspar and quartz in granite and gneiss. It sometimes forms short beds, in granite and other primi- tive rocks. Most of the mica of commerce is brought from Siberia, where it is used for window-glass. MICRO COSMIC SALTS. A triple salt of soda, ammonia, and phosphoric acid, ob- tained from urine, and much used in assays by the blowpipe. This compound is best procured, by mixing equal parts of the phos- phate of spda and phosphate of ammonia in solution, and then crystallizing. A faint excess of ammonia is useful in the solution. See SALT. MIEMITE ; of which there are two kinds, the granular and prismatic, both sub-species of dolomite. Granular miemife. Colour pale asparagus- MIL 609 MIL green. Massive, in granular distinct con- cretions, and crystallized in flat double three- sided pyramids. Lustre splendent, pearly. Cleavage threefold oblique angular. Trans- lucent. Semi-hard. Brittle. Sp. gr. 2.885. It dissolves slowly, and with little effer- vescence, in cold nitric acid. Its constituents are, carbonate of lime 53, carbonate of magnesia 42.5, carbonate of iron, with a little manga- nese, 3.0. It is found at Miemo in Tuscany, imbedded in gypsum, at Hall in the Tyrol, and in Greenland. Prismatic miemitc. Colour asparagus- green. It occurs in prismatic distinct con- cretions, and crystallized in flat rhomboids, which are deeply truncated on all their edges. Internally shining. Fracture passes from concealed foliated to splintery. Strongly translucent. As hard as the former. Sp. gr. 2.885. It dissolves like the other. Its constituents are, lime 33, magnesia 14.5, oxide of iron 2.5, carbonic acid 47-25, water and loss 2.75. Klapr. It occurs in cobalt veins that, traverse sandstone, at Gliieksbrunn in Gotha. MILK is a well known fluid, secreted in peculiar vessels of the females of the human species, of quadrupeds, and of cetaceous animals, and destined for the purpose of nourishing their young. When milk is left to spontaneous decom- position, at a due temperature, it is found to be capable of passing through the vinous, acetous, and putrefactive fermentations. It appears, however, probably on account of the small quantity of alcohol it affords, that the vinous fermentation lasts a very short time, and can scarcely be made to take place in every part of the fluid at once by the addition of any ferment. This seems to be the reason why the Tartars, who make a fermented liquor, or wine, from mare's milk, called koumiss, succeed by using large quantities at a time, and agitating it very frequently. They add as a ferment a sixth part of water, and an eighth part of the sourest cow's milk they can get. or a smaller portion of koumiss already prepared: cover the vessel with a thick cloth, and let it stand in a moderate warmth for 24 hours : then beat it with a stick, to mix the thicker and thinner parts, which have separated : let it stand again 24 hours in a high narrow vessel, and repeat the beating, till the liquor is perfectly homogeneous. This I liquor will keep some months, in close vessels, and a cold place ; but must be well mixed by beating or shaking every time it is used. They sometimes extract a spirit from it by : distillation. The Arabs prepare a similar I liquor by the name of lelan, and the Turks j by that of yaourt. Eton informs us, that, when properly prepared, it may be left to stand till it ; becomes quite dry ; and in this state it is kept in bags, and mixed with water when wanted for use. The saccharine substance, upon which the fermenting property of milk depends, is held in solution by the whey, which remains after the separation of the curd in making cheese. This is separated by evaporation in the large way, for pharmaceutical purposes, in various parts of Switzerland. When the whey has been evaporated by heat, to the consistence of honey, it is poured into proper moulds, and exposed to dry in the sun. If this crude sugar of milk be dissolved in water, clarified with whites of eggs, and evaporated to the consistence of syrup, white crystals, in the form of rhomboidal parallelopipedons, are obtained. Sugar of milk has a faint saccharine taste, and is soluble in three or four parts of water. It yields by distillation the same products that other sugars do, only in somewhat dif- ferent proportions. It is remarkable, however, that the empyreumatic oil has a smell resem- bling flowers of benzoin. It contains an acid frequently called the saccholactic ; but as it is common to all mucilaginous substances, it has been termed mucic. See ACID (Mucic). The kinds of milk that have been chemi- cally examined, are mare's, woman's, ass's, goat's, sheep's, and cow's. We have here placed them according to the proportion of sugar they afforded ; and this, Parmentier observes, was precisely of the same quality in all, while all the other parts varied in quality as well as quantity in the different milks. With regard to the whey, they rank in the following order : ass's, mare's, woman's, cow's, goat's, sheep's : to cream ; sheep's, woman's, goat's, cow's, ass's, mare's: to butter ; sheep's, goat's, cow's, woman's : to cheese ; sheep's, goat's, cow's, ass's, woman's, mare's. Parmentier could not make any butter from the cream of woman's, ass's, or mare's milk ; and that from sheep he found always remained soft. From their general properties, he has divided them into two classes, one abounding in serous and saline parts, which includes ass's, mare's, and wo- man's ; the other rich in caseous and butyra- ceous parts, which are cow's, goat's, and sheep's. Cream, sp. gr. 1.0244 by Berzelius's ana- lysis, consists of butter 4.5, cheese 3.5, whey 92. Curd, by the analysis of MM. Gay Lussac and Thenard, is composed of Carbon, 59.781 Oxygen, 11.400 Hydrogen, 7.429 Asote, 21.381 100.000 Whey always reddens vegetable blues, from the presence of lactic acid. Milk, according to Berzelius, consists of, Water, .... 928.75 Curd, with a little cream, - 28.00 Sugar of milk, 35.00 Muriate of potash, - - 1-70 Phosphate of potash, 0.25 R R 1 MIN 610 MIN Laclic acid, acetate of potash, with a trace of lactate of J> C.OO iron, - Earthy phosphates, - - 0.30 1000.00 Since both cream and water affect the spe- cific gravity of milk alike, it is Kot possible to infer the quality of milk from the indications merely of a specific gravity instrument. We must first use as a lactometer a graduated glass tube, in which we note the thickness of the stratum of cream afforded, after a proper interval, from a determinate column of new milk. We then apply to the skimmed milk a hydrometric instrument, from which we learn the relative proportions of curd and whey. Thus, the combination of the two instruments furnishes a tolerably exact lactometer. MILK QUARTZ. See QUARTZ. MILT of the Carp. It contains, according to Fourcroy and Vauquelin, albumen, gelatin, phosphorus, phosphate of lime, phosphate of magnesia, and muriate of ammonia. 1VIINDERERUS' SPIRIT. Liquid ace- tate of ammonia. MINERALOGY. That department of natural history which teaches us to describe, recognize, and classify, the different genera and species of the objects of inorganic nature. As the greater part of these are solids, ex- tracted from the earth by mining, they are called MINERALS. The term FOSSIL is now commonly restricted to such forms of organic bodies as have been penetrated with earthy or metallic matters. Professor Mohs of Freyberg has lately published a work, replete with profound gene- ral views on mineralogy, which promises to place the science on a surer basis than it has hitherto stood. Werner first taught mineralogists to con- sider the productions of inorganic nature in a state of mutual connexion, resulting from mineralogical similarity. Thus, heavy spar is plainly more similar to calcareous spar than felspar is ; felspar than garnet ; garnet than iron-glance; iron-glance than native gold ; and so on. A collection of species connected by the highest, and at the same time equal degrees of natural-history similarity, is named a genus. The same occurs in zoology and botany. Thus, the wolf, dog, fox ; the lion, tiger, cat, unite into genera. Individuals whose forms belong to two different systems of crystalliza- tions cannot be united in the same species. Radiated hepatic, and cristated iron pyrites, therefore, constitute a distinct species. Yet this species is so similar to that of common iron pyrites (tessular), that we must unite them into one .genus. An order comprehends several analogous genera ; and a class, analogous orders. The specific character consists particularly of three characters. These are, the crystal- line forms (including cleavage), the degrees of hardness, and the specific gravity. The crys- talline forms may be reduced in all cases to one of four SYSTEMS of CRYSTALLIZA- TION: the RHOMBOHEDRAL ; the PYRA- MIDAL, derived from a four-sided isosceles pyramid ; the PRISMATIC, derived from a scalene four-sided pyramid; and lastly the TESSULAR, or that which is derived from the hexahedron. When we wish to determine the species to which any mineral belongs, by means of a tabular view, we must first ascertain either its primitive form or cleavage, and afterwards the hardness and specific gravity. The de- grees of hardness are expressed by Mohs in the following manner : 1 expresses the hardness of Talc, 2 Gypsum, 3 Calcareous spai, 4 Fluor spar, 5 Apatite, 6 Felspar, 7 Quartz, 8 Topaz, 9 Corundum, 10 Diamond. Professor Mohs has arranged minerals into three classes. I. Character of the first class. If solid ; sapid. No bituminous odour. Sp. gr. under 3.8. It has 4 ordftrs. Order 1 . Gas, Expansible. Not acid. 2. Water. Liquid. Without odour or sapidity. Sp. gr. 1. 3. Acid. Acid. Specific gravity, 0-0015 to 3.7. 4. Salt. Not acid. Sp. gr. 1.2 to 2.9. II. Character of the second class. Insipid. Sp. gr. above 1-8. Order 1. Haloide (salt-like). Not metallic. Streak uncoloured. If pyramidal or prismatic ; H. hardness, = 4 and less. If tessular, H. =: 4.0. If single, perfect, and eminent faces of cleavage ; sp. gr. = 2-4 and less. H. = 1-5 to 5-0. If under 2-5, sp. gr. = 2-4 and less. Sp. gr. 2-2 to 3-3. If 2-4 and less, H. under 2-5; and no resinous lustre. Order 2. Baryte. Not metallic. If adamantine or imperfect metallic lustre; sp. gr. = 6.0 and more. Streak uncoloured, or orange-yellow. If orange-yellow ; sp. gr. rr 6.0 and more, and H. = 3.0 and less. H. = 2-5 to 5-0. If 5-0 ; sp. gr. under 4-6. Sp. gr. = 3-3 to 7-2. If under 4-0 and H. 5-0 ; cleavage diprismatic. Order 3. Kerate (Horny). Not metallic. Streak uncoloured. No MIN 611 MIN single eminent cleavage. H. 1-0 to 2-0. Sp. gr. = 5-5. Order 4. Malachite. Not metallic. Colour blue, green, brown. If brown colour of streak ; H. 3-0 and less ; and sp. gr. above 2-5. If uncoloured streak; sp.gr. = 2-2 and less; and H. = 3-0. No single eminent faces of cleavage. H. = 2-0 to 5-0. Sp. gr. = 2-0 to 4-6. Order 5. Mica. If metallic ; Sp. gr. under 2-2. If not metallic ; sp. gr. above 2-2. If yellow streak ; pyramidal Single eminent cleavage. H. = 1-0 to 4-5. If above 2-5; rhombohedral. Sp. gr. = 1-8 to 5-6. If under 2-5; metallic. If above 4-4 ; streak uncoloured. Order 6. Spar. Not metallic. Streak uncoloured, brown. If rhombohedral ; sp. gr. 2-2 and less, or H. = 6-0. H. = 3-5 to 7- If 4-0 and less ; single eminent cleavage. If above 6-0; sp. gr. under 2-5, or above 2-8 ; and pearly lustre. Sp. gr. = 2-0 to 3-7- If above 3-3 ; hemi- prismatic, or H. 6-0 ; and no adamantine lustre. If 2.4 and less ; not without traces of form and cleavage. Order 7- Gem. Not metallic. Streak uncoloured. H. = 5-5 to 10. If 6-0 and less ; sp. gr. = 2-4 and less ; and no traces of form and cleavage. Sp. gr. 1-9 to 47. If under 3-8; no pearly lustre. Order 8. Ore. If metallic ; black. If not metallic ; ada- mantine, or imperfect metallic lustre. If yel- low or red streak j H. =3.5 and more ; and sp. gr. =4.8 and more. If brown or black streak; H. = 5-0 and more, or perfectly prismatoidal. H. = 2-5 to 7-0. If 4-5 and less ; red, yellow, or black streak. If 6-5 and more ; and streak uncoloured ; sp. gr. = 6.5 and more. Sp. gr. = 3-4 to 7-4. Order 9. Metal. Metallic. Not black. If gray; malleable; and sp. gr- = 7-4 and more. H. =. 0-0 to 4-0 or malleable. Sp. gr. = 5-7 to 20-0. Order 10. Pyrites. Metallic. H. =3-5 to 6-5. If 4-5 and less; sp. gr. under 5-0. Sp. gr. = 4-1 to 7-7- If 5-3 and less ; colour yellow or red. Order 11. Glance. Metallic. Gray, black. H. 1-0 to4-O.Sp. gr. = 4-0 to 7-6. If under 5-0, and single perfect cleavage, lead-gray. If above 7-4 ; lead gray. Order 12. Blende. If metallic; black. If not metallic ; ada- mantine lustre. If brown streak ; uncoloured. Sp. gr. between 4-0 -and 4-2 ; and the form, tessular. If red streak ; sp.gr. = 4-5 and more ; and H. =2-5 and less. H. = 1-0, 4-0. Sp. gr. - 3-9, 8-2. If 4-3 and more ; streak red. Order 13. Sulphur. Not metallic. Colour red, yellow, or brown. Prismatic. H. = 1-0 to 2-5. Sp. gr. = 1-9 to 3-6. If above 2-1 ; streak yellow, or red. CLASS III. If fluid; bituminous odour. If solid ; insipid. Sp. gr. under 1-8. Order 1. Resin. Fluid, solid. Streak uncoloured, yellow, brown, black. H. = 0-0 to 2-5. Sp. gr. = 0-7 to 16. If 1-2 and more; streak unco- lourod. Order 2. Coal. Solid. Streak, brown, black. H. =0-1 to 2-5. Sp. gr. = 1.2 to 1-5. GENERA. CLASS I. Order 1. Gas. Genera. 1. Hydrogen. 2. Atmospheric air. Order 2. Water. Genus. 1. Atmospheric water. Order 3. Acid. Genera. 1. Carbonic. 2. Muriatic. 3. Sul- phuric. 4. Boracic ; and 5. Arsenic. Order 4. Salt. Genera. 1. Natron-salt. 2. Glauber-salt. 3. Nitre-salt. 4. Rock-salt. 5. Ammoniac- salt. 6. Vitriol-salt j comprising as species, the sulphates of iron, copper, and zinc. 7. Epsom-salt. 8. Alum-salt. 9. Borax-salt. 10. Barythine-salt (heavy-salt). Glauberite. CLASS II. Order 1. Haloide. Genera. 1. Gypsum -haloide. 2. Cryone- haloide. 3. Alum-haloide. 4. Fluor-haloide. 5. Calc-haloide. Order 2. Baryte. Genera. 1. Parachrose-baryte (altered co- lour). 2. Zinc-baryte. 3. Scheelium-baryte. 4. Hal-baryte. 5. Lead-baryte. Order 3. Kerate. Genera. 1. Pearl-kerate. Order 4. Malachite. Genera. 1. Staphyline-malachite (grape like). 2. Lirocone-malachite (form unknown). 3. Olive malachite. 4. Azure-malachite. 5. Emerald-malachite. 6. Habroneme-malachite (fine threaded). Order 5. Mica. Genera. 1. Euchlore-mica (bright green). 2. Antimony-mica. 3. Cobalt-mica. 4. Iron- mica. 5. Graphite-mica. 6. Talc-mica. T. Pearl-mica. Order 6. Spar. Genera. 1. Schiller-spar. 2. Disthene- spar. 3. Triphane-spar. 4. Dystome-spar (difficult to cleave). 5. Kouphone-spar (light). 6. Petaline-spar. 7. Felspar. 8. Augite-spar. 9. Azure-spar. Order 7- Gem. Genera. 1. Andalusite. 2. Corundum. 3. Diamond. 4. Topaz. 5. Emerald. 6. Quartz. 7. Axinite. 8. Chrysolite. 9. Bo- RR2 MOC MOR racite. 10. Tourmaline. 11. Garnet. 12. Zircon. 13. Gadolinite. Order 8. Ore,. Genera. 1. Titanium-ore. 2. Zinc-ore. 3. Copper-ore. 4. Tin-ore. 5. Scheelium-ore. 6. Tantalum-ore. 7 Uranium-ore. 8. Ceri- um-ore. 9. Chrome-ore. 10. Iron-ore. 11. Manganese-ore. Order 9. Metal Genera. 1. Arsenic. 2. Tellurium. 3. Antimony. 4. Bismuth. 5. Mercury. G. Sil- ver. 7- Gold. 8. Platina. 9. Iron., 10. Copper. Order 10. Pyrites. Genera. 1. Nickel -pyrites. 2. Arsenic- pyrites. 3. Cobalt-pyrites. 4. Iron-pyrites. 5. Copper-pyrites. 'Order 11. Glance. Genera. 1. Copper-glance. 2. Silver-glance. 3. Lead-glance. 4. Tellurium-glance. 5. Molybdena-glance. 6. Bismuth-glance. 7- Antimony-glance. 8. Melane-glance (black). Order 12. Blende. Genera. 1. Glance-blende. 2. Garnet- blende. 3. Purple-blende. 4. Ruby-blende. Order 13. Sulphur. 1. Sulphur. CLASS III. Order 1. Resin. Genus. Melichrone-resin (honey-coloured). Order 2. Coal. Genus. Mineral-coal. Such are the genera of Professor Mohs. I would willingly have introduced a view of the species ; but his symbols of their crystalline structure, and forms, would require a detailed explanation, inconsistent with the limits of this work. An account of his new system of crystallography is given by one of his pupils in the 3d vol. of the Edin. Phil. Journal. But the Professor promises soon to publish that system himself; which, if we may judge from the luminous exposition of the charac- teristic of his NATURAL HISTORY SYSTEM, recently published, will be a great acquisition to mineralogical science. This has been ably translated into English by M. Haidinger, himself an excellent mineralogist. MINERAL CAOUTCHOUC. See CA- OUTCHOUC. MINERAL CHARCOAL. See CHAR- COAL (MINERAL). MINERAL OIL. See PETROLEUM. MINERAL PITCH. See BITUMEN. MINERALIZER. Metallic substances are said to be mineralized when deprived of their usual properties by combination with some other substance. MINER'S SAFETY LAMP. See LAMP. MINIUM. Red cxide of lead. MIRRORS. See SPECULUM; also SIL- VERING. MISPICKEL. Arsenical pyrites. MOCHA-STONE. See AGATE. MOIREE METALLIQUE. When we pour on heated tin-plate a mixture of 2 parts of the nitric acid of commerce, and 3 of mu- riatic acid diluted with 8 of water, we obtain, after washing, a beautiful crystalline surface. in plumose forms, which was first observed a few years ago by M. Alard. It is usually called in this country crystallized tin-plate; and, when varnished, it is worked into orna- mental vessels. The figures vary, according to the degree of heat previously given to the metal. MOLYBDATE OF LEAD. See ORES or LEAD. MOLYBDENUM. A metal which has not yet been reduced into masses of any mag- nitude ; but has been obtained only in small separate globules, in a blackish brilliant mass. This may be effected by making its acid into a paste with oil, bedding it in charcoal in a crucible, and exposing it to an intense heat. The globules are gray, brittle, and extremely infusible. By heat it is converted into a white oxide, which rises in brilliant needle- formed flowers, like those of antimony. Nitric acid readily oxidizes and acidifies the metal. Nitre detonates with it, and the remaining alkali combines with its oxide. Molybdenum unites with several of the metals, and forms brittle or friable com- pounds. No acid acts on it but the nitric and nitromuriatic. Several acids act on its oxide, and afford blue solutions. See ACID (MOLYBDIC). The sp. gr. of molybdenum is 8-611. When dry molybdate of ammonia is ignited in a crucible with charcoal powder, it is con- verted into the brown oxide of the metal. This has a crystallized appearance, a copper- brown colour, and a sp. gr. of 5-66. It does not form salts with acids. The deutoxide is molybdous acid, which see. MONTMARTRJTE. Its colour is yel- lowish ; it occurs massive, but never crystal- lized. It is soft. It effervesces with nitric acid. It is a compound of 83 sulphate of lime, and 17 carbonate of lime, which is found at Montmartre, near Paris. It stands the weather, which common gypsum does not bear. MOONSTONE. A variety of adularia. MOOR-COAL. Sec COAL. MORASS-ORE. Bog-iron ore. MORDANT. In dyeing, the substance combined with the vegetable or animal fibre, in order to fix the dye-stuff. It also usually modifies the colour. See DYEING. MOROXYLATES. Compounds of mo- j roxylic acid with the salifiable bases. MOROXYLIC ACID. See ACID (Mo- ; ROXYLIC). MOROXITE. Apatite of a blue-green colour from Norway. MORPHIA. A new vegetable alkali, MOR 613 MOR extracted from opium, of which it constitutes the narcotic principle. It was first obtained pure, by M. Sertiirner, about the year 1817. Two somewhat different processes for pro- curing it have been given by M. Robiquet and M. Choulant. According to the former, a concentrated in- fusion of opium is to be boiled with a small quantity of common magnesia for a quarter of an hour. A considerable quantity of a grayish deposite falls. This is to be washed on a filter with cold water, and when dry, acted on by weak alcohol for some time, at a temperature beneath ebullition. In this way very little morphia, but a great quantity of colouring matter, is se- parated. The matter is then to be drained on a filter, washed with a little cold alcohol, and afterwards boiled with a large quantity of highly rectified alcohol. This liquid being fil- tered while hot, on cooling it deposits the mor- phia in crystals, and very little coloured. The solution in alcohol, and crystallization, being repeated two or three times, colourless morphia is obtained. The theory of this process is the following : Opium contains ameconiate of morphia. The magnesia combines with the meconic acid, and the morphia is displaced. Choulant directs us to concentrate a dilute watery infusion of opium, and leave it at rest till it spontaneously let fall its sulphate of lime in minute crystals. Evaporate to dryness; re- dissolve in a little water, and throw down any remaining lime and sulphuric acid, by the cautious addition, first of oxalate of ammonia, and then of muriate of barytes. Dilute the liquid with a large body of water, and add caustic ammonia to it, as long as any preci- pitate falls. Dissolve this in vinegar, and throw it down again with ammonia. Digest on the precipitate about twice its weight of sulphuric ether, and throw the whole upon a filter. The dry powder is to be digested three times in caustic ammonia, and as often in cold alcohol. The remaining powder being dis- solved in twelve ounces of boiling alcohol, and the filtered hot solution being set aside for 18 hours, deposits colourless transparent crystals, consisting of double pyramids. By concen- trating the supernatant alcoholic solution, more crystals may be obtained. The following process of M. Hottot is much commended. Opium is to be dissolved in so much water as to yield a solution of a specific gravity not higher than 1-012. A small quantity of am- monia is then to be added, just sufficient to precipitate the colouring matter of the solution. In consequence of the diluted state of the liquor this readily falls to the bottom. The clear solution is then removed, and more am- monia added to it to precipitate the morphia. The vegetable tilkali separates, and falls on standing, as a crystalline sediment, containing very little colouring matter. This washed with cold water, and afterwards treated with alcohol, sp. gr. 0-840, and a little animal charcoal, gives by the first operation, a mor- phia so pure as to require no further solution in alcohol, or union with sulphuric acid. By this process a considerable quantity of mor- phia may be obtained in 24 hours, with very little waste of alcohol. The only point to be attended to, is to separate carefully the fatty matter which falls in the first instance, on add- ing a small quantity of ammonia, so that it may not be redissolved by the addition of the further quantity of ammonia necessary to throw down the morphia. The product by the magnesia process was rarely so white and pure as that of the above method ; nor was the quantity so great Jour- nal de Pharm. x. 475. M. Choulant says, it crystallizes in double four-sided pyramids, whose bases are squares or rectangles. Sometimes in prisms with trapezoidal bases. It dissolves in 82 times its weight of boiling water, and the solution on cooling deposits regular, colourless, transparent crystals. It is soluble in 36 times its weight of boiling alco- hol, and in 42 times its weight of cold alcohol, of 0-92. It dissolves in eight times its weight of sulphuric ether. All these solutions change the infusion of brazil-wood to violet, and the tincture of rhubarb to brown. The saturated alcoholic and ethereous solutions, when rub- bed on the skin, leave a red mark. Sulphate of morphia crystallizes in prisms, which dissolve in twice their weight of dis- tilled water. They are composed of Acid, 22 Morphia, 40 Water, 38 100 5-00 9-09 Nitrate of morphia yields needle-form crys- tals in stars, which are soluble in l times their weight of distilled water. Its consti- tuents are, Acid, 20 6-75 Morphia, 36 12-15 Water, 44 100 Muriate of morphia is in feather-shaped crystals, and needles. It is soluble in lOtr times its weight of distilled water. Its con- stituents are, Acid, 35 4-625 Morphia, 41 5-132 Water, 24 100 The acetate crystallizes in needles ; the tar- trutc in prisms ; and the carbonate in short MOR 614 MUC prisms. Dr. Thomson states the ultimate constituents of morphia to be Hydrogen, 0-0555 Carbon, 0-4528 Oxygen, 04917 1-0000 from the analysis of one grain, by ignited per- oxide of copper. He imagines the atom to be either 40-25, or 20-125. MM. Dumas and Pelletier, in their exten- sive memoir on organic salifiable bases, observe on morphia, that Dr. Thomson's results are affected by some inaccuracy proceeding undoubtedly from the analytical method which he employed ; for M. Bussy, of the school of pharmacy, had lately published a well-con- ducted analysis of morphia, in which he found azote, a principle which Dr. Thomson had not supposed to exist in it. M. Bussy shows also a much larger proportion of carbon, as we may perceive, by comparing his results with the preceding. Carbon, . 69-0 Hydrogen, 6-5 Azote, ... 4-5 Oxygen, - 20-0 100-0 MM. Dumas and Pelletier made the ulti- mate analysis of morphia on two very pure specimens extracted by different methods. The mean of the two results, which differed very little, and which they regard as very exact, was, Carbon, - 72-02 Hydrogen, - 7'G1 Azote, - - 5-53 Oxygen, . - 14-84 100-00 Ann. de Chim. xxiv. 184. Mr. Brande's analysis gives, #s the mean of three experiments ; Carbon, . 72-00 Hydrogen, . . 5-50 Azote, - - . 5-50 ' , * Oxygen, - 17-00 100-00 Journal of 'Science, xvi. 284. The near coincidence of these analytical re- sults, places the errors of Dr. Thomson's in a very strong light. The prime equivalent of morphia seems to be about 40 by Pelletier and Caventou, which is probably more exact than the number de- ducible from Choulant. Tincture of galls is said to be a good test of morphia free or combined. Subacetate of lead throws down all the ani- mal matters with which acetate of morphia may come to be associated in the stomach, without acting on that vegetable salt. The excess of lead may be separated from the clear liquor by a few bubbles of sulphuretted hy- drogen ; and the morphia may then be recog- nized by crystallization in -vacua, and by the red colour which nitric acid imparts to it. No morphia is found in the blood of animals killed with it. Ann. de Chimie, xxv. 105. Morphia acts with great energy on the ani- mal economy. A grain and a half taken at three different times, produced such violent symptoms upon three young men of 17 years of age, that Serturner was alarmed lest the con- sequences should have proved fatal. Morphia, according to its discoverer, melts in a gentle heat ; and in that state has very much the appearance of melted sulphur. On cooling, it again crystallizes. It burns easily ; and when heated in close vessels, leaves a solid resinous black matter, having a peculiar smell. MORTAR CEMENT. A mixture of lime and siliceous sand, used in masonry for cementing together the stones and bricks of a building. The most precise ideas which we have on this subject were given by Sir H. Davy in his Agric. Chem. See LIME and CEMENT. MOSAIC GOLD. See AURUM Musi- VUM. MOTHER OF PEARL shells are com- posed of alternate layers of coagulated albumen and carbonate of lime, in the proportion, by Mr. Hatchett, of 24 of the former and 76 of the latter, in 100 parts. MOTHER WATER. When sea-water, or any other solution containing various salts, is evaporated, and the crystals taken out ; there always remains a fluid containing deli- quescent salts, and the impurities, if present. This is called the mother water. MOULD. See SOIL, MANURE, and ANALYSIS (VEGETABLE). MOUNTAIN BLUE. Malachite; car- bonate of copper. MOUNTAIN CORK and MOUNTAIN LEATHER. SeeAssESTus. MOUNTAIN GREEN. Common cop- per green ; a carbonate of copper. MOUNTAIN or ROCK WOOD. See ASBESTUS. MOUNTAIN SOAP. Colour pale brown- ish-black. Massive. Dull. Fracture fine earthy. Opaque. Streak shining. Writes, but does not soil. Soft. Sectile. Easily frangible. Adheres strongly to the tongue. Feels very greasy. It is light, bordering on rather heavy. It occurs in trap rocks in the island of Skye. It is used in crayon-painting. MOUNTAIN TALLOW. See TAL- LOW. MUCILAGE. An aqueous solution of gum. MUCUS. This, according to Dr. Bostock, is one of the primary animal fluids, perfectly distinct from gelatin. NAP 615 NAT The subacetate of lead does not affect ge- latin ; on the other hand, tannin, which is a delicate test of gelatin, does not affect mucus. Both these reagents, however, precipitate albu- men; but the bichloride of mercury, which will indicate the presence of albumen dissolved in 2000 parts of water, precipitates neither mucus nor gelatin. Thus we have three di- stinct and delicate tests for these three dif- ferent principles. Gum appears to resemble mucus in its pro- perties. One grain of gum-arabic, dissolved in 200 of water, was not affected by bichloride of mercury, or by tannin, but was imme- diately precipitated by subacetate of lead. MUFFLE. A small earthen oven, made and sold by the crucible manufacturers. It is to be fixed in a furnace, and is useful for cupellation, and other processes which demand access of air. MULLER'S GLASS. Hyalite. MURIAC1TE. Gypsum. MURIATIC ACID. See ACID (MU- RIATIC). MURICALCITE. Rhomb-spar. MUSCLES OF ANIMALS. SeeFiBKiN and FLESH. MUSCOVY GLASS. Mica. MUSHROOMS. See BOLETUS. MUSSITE. Diopside. MUST. The juice of grape, composed of water, sugar, jelly, gluten, and bitartrate of potash. From a French wine pint of must, the Marquis de Bullion extracted half an ounce of sugar, and 1-1 6th of an ounce of tartar. Proust says, the muscaditi? grape con- tains about 30 per cent, of a peculiar species of sugar. By fermentation it forms wine. MYRICIN. The ingredient of wax which remains after digestion with alcohol. It is insoluble likewise in water and ether; but very soluble in fixed and volatile oils. Its melting point is about 120. Sp. gr. 0-90. Its consistence is waxy. MYRRH. A gum resin, which consists, according to Braconnot, of Resin, containing some volatile oil, 33-68 Gum, 66-32 100-00 N NACRITE. See TALCITE. NADLESTEIN. Rutile. NAILS, consist of coagulated albumen, with a little phosphate of lime. NANKIN DYE. See IRON, towards the end. NAPHTHA. A native combustible li- Suid, of a yellowish-white colour, perfectly uid and shining. It feels greasy, exhales an agreeable bituminous smell, and has a specific gravity of about 0-7- It takes fire on the ap- proach of flame, affording a bright white light. It occurs in considerable springs on the shores of the Caspian Sea, in Sicily and Italy. It is used instead of oil, and differs from the petro- leum obtained by distilling coal tar, only by its greater purity and lightness. By Dr. Thom- son's recent analysis of a specimen of naphtha from Persia, whose sp. gr. was 0-753, and boiling point 320, it appears to be composed of carbon 82-2 -\- hydrogen 14-8, with perhaps a little azote. By my analysis, naphtha, specific gravity 0.857, boiling point 316 Fahr., contains in 100, carbon 83.04, hydrogen 12.31, oxygen 4.65 ; which is very nearly Carbon, 22 atoms 16.5 82.5 Hydrogen, 20 2.5 12.5 Oxygen, 1 1.0 5.0 It is therefore resolvable into 20 atoms of olefiant gas, 1 atom carbonic oxide holding 1 atom of cavbon in combination. - Phil. Trans, 1822. NAPHTHALINE. A grayish-white sub- stance found during the rectification of the petroleum of the coal gas works, incrusting the pipes. It may be obtained in thin white scales of a pearly brightness, by slow re- sublimation in glass vessels. Its spec. grav. is 1.048. It has a strong odour of naphtha. It is insoluble in water, but very soluble in ether, and moderately so in alcohol and oils. In water heated to 168 Fahr. it fuses, and remains at the bottom of the liquid, but when stirred it rises, and spreads on the top in oily patches. At 180 it rises spontaneously from the bottom in oily looking globules, which, as the temperature is raised, dissipate in the air, undergoing motions similar to those of camphor floating on water. Naphthaline is, according to my analysis, a solid bicarburet of hydrogen, consisting of Carbon, 2 atoms 1-5 92-9 Hydrogen, 1 0-125 7-1 -ran IT* nun NAPLES YELLOW. According to Professor Beckmann, this colour is prepared by calcining lead with antimony and potash in a reverberatory furnace. NATRON. Native carbonate of soda, of which there are two kinds, the common and radiated. See SODA. NATROLITE. A sub-species of prisma- tic zeolite or mesotype. Colour yellowish. Massive, in plates and rcniform. Seldom NEP 616 NIC crystallized. Crystals aclcular. Lustre glis- tening, pearly. Translucent on the edges. Specific gravity 2.2. Before the blowpipe it becomes first black, then red, intumesces, and melts into a white compact glass. Its con- stituents are, silica 48.0, alumina 24.25, natron 16.5, oxide of iron 1.75, and water 9. It occurs in chalkstone porphyry in Wurtemberg and Bohemia, and in the trap- tuff hill named the Bin, behind Burntisland, in Scotland. NECROMITE. A mineral found near Baltimore, in small masses, of a white colour, in limestone. It possesses a disagreeable odour. NEEDLE ORE. Acicular bismuth glance. NEEDLE ZEOLITE, Colour grayish- white. Massive ; in distinct concretions ; and crystallized in acicular rectangular four-sided prisms, variously acuminated and truncated. The lateral planes are longitudinally streaked. Glistening, inclining to pearly. Cleavage twofold, in the direction of the lateral plane of the prism. Translucent. Refracts double. As hard as apatite. Brittle. Spec. grav. 2.3. It intumesces before the blowpipe, and forms a jelly with acids. It becomes electric by heating, and retains this property some time after it has cooled. The free extremity of the crystal, with the acumination, shows positive, and the attached end negative electricity. Its constituents are, silica 50.24, alumina 29.3, lime 9.46, water 10. It occurs in secondary trap rocks near the village of Old Kilpatrick in Scotland. NEPHELINE. Rhomboidal felspar. Colour white. Massive and crystallized. The primitive form is a dirhomboid of 152 44', and 56 15'. The secondary forms are, a perfect equiangular six-sided prism ; the same truncated on the terminal edges ; and a thick six-sided table, with the lateral edges all trun- cated. The crystals form druses. Lustre splendent, vitreous. Cleavage fourfold. Frac- ture conchoidal. Translucent and transparen t. As hard as felspar. Spec. grav. 2.6 to 2.7- It melts with difficulty before the blowpipe. Its constituents are silica 46, alumina 49, lime 2, oxide of iron 1. It occurs in drusy cavities, along with ceylanite, vesuvian, and meionite, at Monte Somma, near Naples, in drusy cavities, in granular limestone. NEPHRITE. Of which mineral there are two kinds; common nephrite and axe- stone. Common nephrite. Colour leek -green. Massive and in rolled pieces. Dull. Frac- ture coarse splintery. Translucent. Nearly as hard as rock-crystal. Difficultly frangible. Feels rather greasy. Rather brittle. Spec, grav. 3. It melts before the blowpipe into a white enamel. Its constituents are, silica 50.3, magnesia 31, alumina 10, iron 5.5, chrome 0.05, water 2.75. Nephrite occurs in granite and gneiss, in Switzerland; and in veins that traverse primitive greenstone in the Hartz. The most beautiful comes from Persia and Egypt. The South American variety is called Amazon stone, from its locality. See AXE STONE. NERIUM TINCTORIUM. A tree growing in Hindostan, which, according to Dr. Roxburgh, affords indigo. NEUTRALIZATION. When acid and alkaline matter are combined in such propor- tions that the compound does not change the colour of litmus or violets, they are said to be neutralized. NICKEL is a metal of great hardness, of an uniform texture, and of a colour between silver and tin; very difficult to be purified, and magnetical. It even acquires polarity by the touch. It is malleable, both cold and red-hot; and is scarcely more fusible than manganese. Its oxides, when pure, are re- ducible by a sufficient heat without combusti- ble matter ; and it is little more tarnished by heating in contact with air, than platina, gold, and silver. Its spec. grav. when cast, is 8.279 ; when forged, 8.666. Nickel is commonly obtained from its sul- phuret, the kupfernickel of the Germans, in which it is generally mixed also with arsenic, iron, and cobalt. This is first roasted, to drive off the sulphur and arsenic, then mixed with two parts of black flux, put into a cru- cible, covered with muriate of soda, and heated in a forge furnace. The metal thus obtained, which is still very impure, must be dissolved in dilute nitric acid, and then evaporated to dryness; and after this process has been re- peated three or four times, the residuum must be dissolved in a solution of ammonia, per- fectly free from carbonic acid. Being again evaporated to dryness, it is now to be well mixed with two or three parts of black flux, and exposed to a violent heat in a crucible for half an hour or more. According to Richter, the oxide is more easily reduced, by moistening with a little oil. Thenard advises to pour chloride of lime on the oxide of nickel, and shake them well toge- ther, before the ammonia is added ; as thus the oxides of cobalt and iron, if present, will be so much saturated with oxygen as to be in- soluble in the ammonia, and consequently may be separated. M. Chenevix observed, that a very small portion of arsenic prevents nickel from being affected by the magnet. Richter found the same. When it is not attractible, therefore, we may be pretty certain that this is present. To separate the arsenic, M. Chenevix boiled the compound in nitric acid, till the nickel was converted into an arseniate ; decomposed this by nitrate of lead, and evaporated the liquor, not quite to dryness. He then poured in alcohol, which dissolved only the nitrate of nickel. The alcohol being decanted and NIC 617 NIC evaporated, he redissolved the nitrate in water, and precipitated by potash. The precipitate, well washed and dried, he reduced in a Hessian crucible lined with lampblack, and found it to be perfectly magnetic ; but this property was destroyed again, by alloying the metal with a small portion of arsenic. Alloying it with copper weakens this property. Nickel and cobalt being usually associated, it becomes an important problem to separate them. See COBALT, et infra. There are two oxides of nickel ; the dark ash-gray, and the black. If potash be added to the solution of the nitrate or sulphate, and the precipitate dried, we obtain the protoxide. It may be regarded as a compound of about 100 metal with 28 of oxygen ; and the prime equivalent of the metal will become 3.6, while that of the protoxide will be 4.6. The per- oxide was formed by Thenard, by passing chlorine through the protoxide diffused in water. A black insoluble peroxide remains at the bottom. The compounds of nickel have been made the subject of experiment by M. Lassaigne. Protoxide of nickel. A given weight of pure nickel was dissolved in pure nitric acid, evaporated to dryness, and decomposed by heat. It was of a gray colour, soluble in acids, precipitated by alkalis, as a hydrate, &c. Composition, Nickel, ... 100 Oxygen, ... 20 Dcutoxide of nickel. Obtained by diffusing hydrate of nickel in water, and passing a cur- rent of chlorine through it. One part is dis- solved, and the other becomes peroxide. It is of a brilliant black colour; heated, it loses oxygen, and becomes protoxide. Acids dis- solve it, liberating oxygen, except muriatic, which disengages chlorine. Its composition, ascertained by its loss of weight when heated, appeared to be Nickel, . . . 100 Oxygen, . . . 39-44; whence the prime equivalent of nickel seems to be 5, on the oxygen scale. Sulphuret of nickel, prepared directly from its elements, is of a yellow colour, like iron pyrites, and very brittle. It was analyzed by calcination with nitre. Coinposition, Nickel, . . . 100 Sulphur, . . . 41-3 Chloride, of nickel, prepared by evaporating the muriate to dryness. It is of a yellow- green colour, and is a protochloride. Com- position, Nickel, ... 100 Chlorine, . . . 90 When the above chloride is calcined in a retort, one portion of an olive-green colour remains in the bottom of the vessel, while another sublimes, and crystallizes in small light brilliant plates of a gold-yellow colour. These are the deutochloride, consisting of Nickel, ... 100 Chlorine, . . . 200 Iodide of nickel, obtained by heating iodine and nickel in a tube. It is a brown substance ; fusible ; soluble in water, colouring it of a light green ; and composed of Nickel, ... 100 Iodine, . . . 320 Ann. de Chimie^ xxi. 255. M. Berthier has given the following as an economical way of preparing pure nickel. Speiss, or the impure nickel of commerce, is to be reduced into fine powder, and roasted until it gives off no farther vapours of arsenic, the heat being at first moderate, to prevent fusion, and then increased. Metallic iron in the state of filings, or nails, is to be added in a quantity which ought to be previously deter- mined, and the whole dissolved in boiling nitro-muriatic acid, so much nitric acid being used that no protoxide of iron shall remain in the solution ; evaporate to dryness, and re- dissolve in water, when a large quantity of arseniate of iron will be left. Add to the solutions successive portions of carbonate of soda, until a greenish precipitate appears, at which time all the arsenic and iron will be separated, and part of the copper ; the rest of the copper may be separated by sulphuretted hydrogen, and the clear solution thus obtained, when boiled with carbonate of soda, yields the carbonate of nickel. Thus obtained, the carbonate of nickel con- tains a little cobalt. To separate the latter, the precipitate as obtained above, by boiling with carbonate of soda, is to be well washed and diffused while moist in water, and a cur- rent of chlorine in excess passed into it. The excess of chlorine is to be allowed to dissi- pate, and the solution is to be filtered. It now contains not the smallest trace of cobalt, which metal remains as a hydrated peroxide with a certain portion of nickel in the same state. Ann. de Chimie, xxv. 95. A compound, resembling meteoric iron, has been made, by fusing together about 5 or 10 parts of nickel with 95 or 90 of iron. The meteoric iron from Baffin's Bay contains 3 per cent, of nickel, the Siberian contains 10 per cent., by Mr. Children's analysis. See Journal of Science, vol. ix. The salts of nickel possess the following general characters. They have usually a green colour, and yield a white precipitate with ferro- prussiate of potash. Ammonia dissolves the oxide of nickel. Sulphuretted hydrogen and infusion of galls occasion no precipitate. The hydrosulphuret of potash throws down a black precipitate. Their composition has been very imperfectly ascertained. The sulphuric and muriatic acids have little action upo'n nickel. The nitric and nitro- muriatic are its most appropriate solvents. The nitric solution is of a fine grass-green co- lour. Carbonji'e of potash throws down from NIT 618 IS! IT it a pale apple-green precipitate, which, when well washecl and dried, is very light. One part of metal gives 2.J)27 of this precipitate, which by exposure to a white heat becomes blackish-gray, barely inclining to green, and weighing only 1.285. By continuing the fire it is reduced. When ammonia is added in excess to a nitric solution of nickel, a blue precipitate is formed, which changes to a purple-red in a few hours, and is converted to an apple-green by an acid. If the precipitate retain its blue colour, copper is present. See SAL T. NICOTIN. A peculiar principle obtained by Vauquelin from tobacco. It is colourless, and has the peculiar taste and smell of the plant It dissolves both in water and alcohol ; is volatile, poisonous, and precipitable from its solutions by tincture of galls. Ann. de Chimie, torn. Ixxi. NIGRINE. An ore of titanium. NIHIL ALBUM. A name formerly given to the flowers or white oxide of zinc. NITRATES. Compounds of nitric acid with the salifiable bases. NITRE. The common name of the ni- trate of potash. See ACID (NITRIC). NITROGEN, or AZOTE, an important elementary or undecomposed principle. As it constitutes four-fifths of the volume of atmo- spheric air, the readiest mode of procuring azote is to abstract its oxygenous associate, by the combustion of phosphorus or hydrogen. It may also be obtained from animal matters, subjected in a glass retort to the action of nitric acid, diluted with 8 or 10 times its weight of water. Azote possesses all the physical properties of air. It extinguishes flame and animal life. It is absorbable by about 100 volumes of wa- ter. Its specific gravity is 0.9722. 100 cubic inches weigh 29.65 grains. It has neither taste nor smell. Quantities of azote inappreciably minute by other tests may be detected in the following way. Put a small piece of clean zinc foil into a glass tube sealed at one end, and about one- fourth of an inch in diameter ; drop a piece of potash into the tube over the zinc ; introduce a slip of turmeric paper slightly moistened at the extremity with pure water, retaining it in the tube in such a position that the wetted portion may be about two inches from the potash ; then, holding the tube in an inclined position, apply the flame of a spirit lamp, so as to melt the potash that it may run down upon the zinc, and heat the two whilst in contact, taking care not to cause such ebulli- tion as to drive up the potash. In a second or two the turmeric paper will be reddened at the moistened extremity, provided that part of the tube has not been heated. On removing the turmeric paper and laying the reddened portion upon the hot part of the tube, the original yellow tint will be restored; from which it may be concluded that ammonia has been formed ; a result confirmed by other modes of examination. Mr. Faraday in Journal of Science, xix. 17. If sea-sand after ignition be handled, it will acquire an azotic impregnation from the skin, sufficient to yield ammonia by turmeric paper when heated in a glass tube ; which the sand itself would not do. Ibid. It unites with oxygen in four proportions, forming four important compounds. These are, 1. Protoxide of azote, or nitrous oxide. 2. Deutoxide of azote, nitrous gas, or nitric oxide. 3. Nitrous acid. 4. Nitric acid. 1. Nitrous oxide ox protoxide of azote, was discovered by Dr. Priestley in 1772, but was first accurately investigated by Sir H. Davy in 1799. The best mode of procuring it, is to expose the salt called nitrate of ammonia, to the flame of an Argand lamp, in a glass retort. When the temperature reaches 400 F. a whitish cloud will begin to project itself into the neck of the retort, accompanied by the copious evolution of gas, which must be collected over mercury for accurate researches, but for common experiments may be received over water. It has all the physical properties of air. It has a sweet taste, a faint agreeable odour, and is condensable by about its own volume of water, previously deprived of its atmospheric air. This property enables us to determine the purity of nitrous oxide. A taper plunged into this gas burns with great brilliancy ; the flame being surrounded with a bluish halo. But phosphorus may be melted and sublimed in it, without taking fire. When this combustible is introduced into it, in a state of vivid combustion, the brilliancy of the flame is greatly increased. Sulphur and most other combustible bodies require a higher degree of heat for their combustion in it, than in either oxygen or common air. This may be attributed to the counteracting affinity of the intimately combined azote. Its sp. grav. is 1.5277. 100 cubic inches weigh 46.6 gr. It is respirable, but not fitted to support life. Sir H. Davy first showed, that by breathing a few quarts of it, contained in a silk bag, for two or three minutes, effects analogous to those occasioned by drinking fermented liquors were produced. Individuals, who differ in temperament, are, however, as we might expect, differently affected. Sir H. Davy describes the effect it had upon him as follows : " Having previously closed my nostrils, and exhausted my lungs, I breathed four quarts of nitrous oxide from and into a silk bag. The first feelings were similar to those produced in the last experi- ment, (giddiness); but in less than half a minute the respiration being continued, they NIT 619 NIT diminished gradually, and were succeeded by a sensation analogous to gentle pressure on all the muscles, attended by an highly pleasurable thrilling, particularly in the chest and the extremities. The objects around me became dazzling, and my hearing more acute. To- wards the last inspiration the thrilling increased, the sense of muscular power became greater, and at last an irresistible propensity to action was indulged in. I recollect but indistinctly what followed : I know that my motions were various and violent. " These effects very soon ceased after respi- ration. In ten minutes 1 had recovered my natural state of mind. The thrilling in the extremities continued longer than the other sensations. " The gas has been breathed by a very great number of persons, and almost every one has observed the same things. On some few, indeed, it has no effect whatever, and on others the effects are always painful. " Mr. J. W. Tobin (after the first imperfect trials), when the air was pure, experienced sometimes sublime emotions with tranquil gestures, sometimes violent muscular action, with sensations indescribably exquisite ; no subsequent debility no exhaustion ; his trials have been very numerous. Of late he has only felt sedate pleasure. In Sir H. Davy the effect is not diminished. "Mr. James Thomson. In voluntary laugh- ter, thrilling in his toes and fingers, exquisite sensations of pleasure. A pain in the back and knees, occasioned by fatigue the day be- fore, recurred a few minutes afterwards. A similar observation, we think, we have made on others ; and we impute it to the undoubted power of the gas to increase the sensibility or nervous power, beyond any other agent, and probably in a peculiar manner. " Mr. Thomas Pople. At first unpleasant feelings of tension ; afterwards agreeable lux- urious languor, with suspension of muscular power ; lastly, powers increased both of body and mind. " Mr. Stephen Hammick, surgeon of the Royal Hospital, Plymouth. In a small dose, yawning and languor. It should be observed that the first sensation has often been disa- greeable, as giddiness ; and a few persons, previously apprehensive, have left off inhaling as soon as they felt this. Two larger doses produced a glow, unrestrainable tendency to muscular action, high spirits, and more vivid ideas. A bag of common air was first given to Mr. Hammick, and he observed that it pro- duced no effect. The same precaution against the delusions of imagination was of course frequently taken. " Mr. Robert Southey could not distinguish between the first effects and an apprehension of which he was unable to divest himself. His first definite sensations were, a fulness and dizziness in the head, such as to induce a fear of falling. This was succeeded by a laugh which was involuntary, but highly pleasurable, accompanied with a peculiar thrilling in the extremities ; a sensation per- fectly new and delightful. For many hours after this experiment, he imagined that his taste and smell were more acute, and is certain that he felt unusually strong and cheerful. In a second experiment he felt pleasure still superior, and has since poetically remarked, that he supposes the atmosphere of the highest of all possible heavens to be composed of this gas. "Robert Kinglake, M. D. Additional freedom and power of respiration, succeeded by an almost delirious, but highly pleasurable sensation in the head, which became universal with increased tone of the muscles. At last, an intoxicating placidity absorbed for five minutes all voluntary power, and left a cheer- fulness and alacrity for several hours. A second stronger dose produced a perfect trance for about a minute ; then a glow pervaded the system. The permanent effects were an in- vigorated feeling of vital power, and improved spirits. By both trials, particularly by the former, old rheumatic feelings seemed to be revived for the moment. " Mr. Wedgewood breathed atmospheric air first, without knowing it was so. He declared it to have no effect, which confirmed him in his disbelief of the power of the gas. After breathing this some time, however, he threw the bag from him, kept breathing on laboriously with an open mouth, holding his nose with his left hand, without power to take it away, though aware of the ludicrousness of his situ- ation : all his muscles seemed to be thrown into vibrating motions ; he had a violent inclination to make antic gestures, seemed lighter than the atmosphere, and as if about to mount. Before the experiment, he was a good deal fatigued after a long ride, of which he perma- nently lost all sense. In a second experiment, nearly the same effect, but with less pleasure. In a third, much greater pleasure." Res. on Nit. Ox. I have often verified these pleasurable effects, on myself and my pupils. The causes of failure, in most cases, I believe to be impure gas, a narrow tube or stop-cock, or precipitate breathing, from fear. If a little sulphate or muriate be mixed with the nitrate of ammonia, it will not yield an intoxicating gas. I use a pretty wide glass tube, fixed to the mouth of a large bladder. I find that mice, introduced into a jar con- taining nitrous oxide, die almost instantly ; while in aeote, hydrogen, and carbonic acid, they struggle for a little while. This gaseous compound may be analyzed by the combustion of hydrogen, carbon, or phosphorus in it. If we mix 100 volumes of nitrous oxide with 100 of hydrogen ; and deto- nate the mixture in an explosive eudiometer, NIT 620 NIT nothing will remain but 100 measures of azote. Hence 50 measures of oxygen, the equivalent quantity of 100 of hydrogen, must have ex- isted in the oxide. It therefore consists of 100 measures of azote -f- 50 of oxygen, con- densed by reciprocal attraction into only 100 measures. Now 100 vol. of azote weigh 0.9722 50 of oxygen, - 0.5555 1.5277 This synthetic sum exactly coincides with the specific gravity of the compound. It is therefore composed by weight of one prime equivalent of azote, = 1.75 63.64 one of oxygen, = 1.00 36.36 2.75 100.00 The weight of the compound prime is the same with that of carbonic acid. Iron wire burns with brilliancy in the above gas, but it is soon extinguished. 2. Deutoxide of azote, or nitric oxide, was first described by Dr. Priestley in 1772. Into a glass retort, containing copper turnings, pour nitric acid diluted with six or eight times its quantity of water, and apply a gentle heat. A gas comes over, which may be collected over water ; but for exact experiments, it should be received over mercury. Its sp. gr. is i-0416. 100 cubic inches weigh 36-77 grains. Water condenses only about $ of its volume of nitric oxide. But a solution of protosulphate or protomuriate of iron absorbs it very copiously, forming a dark coloured liquid, which is used for condensing oxygen, in the eudiometer of Sir H. Davy. When a jar of nitric oxide is opened in the atmosphere, red fumes appear in consequence of the absorption of oxygen, and formation of nitrous acid. When an animal is made to inhale this gas, it is instantly destroyed by the formation of this acid, and condensation of the oxygen in its lungs. When a burning taper is immersed in this gas, it is extinguished ; as well as the flame of sulphur. But inflamed phosphorus burns in it with great splendour. A mixture of hydrogen gas and nitric oxide bums with a lambent green flame, but does not explode by the electric spark; though Fourcroy says that it detonates on being passed through an ignited porcelain tube. The py- rophorus of Homberg spontaneously burns in it. It is decomposable by several of the metals, when they are heated in it. such as arsenic, zinc, and potassium in excess. It oxidizes them, and affords half its volume of azote. Charcoal ignited in it by a burning glass produces half a volume of azote, and half a volume of carbonic acid. All these analytical experiments concur to show, that nitric oxide consists of oxygen and azote, in equal volumes. Hence, if we take the mean weight of a volume of eacli gas, we shall have that of the gaseous compound j or, its sp. gr. Sum. Hf. sum, or sp. gr. Azote, 0-9722 > 6 Oxygen, 1-1111 If we convert these into equivalent ratios, we shall have the gas composed of 1 prime of azote = 1-75 46-66 2 primes oxygen = 2-00 53-33 100-00 When this deutoxide is exposed, at ordinary temperatures, to bodies which have a strong attraction for oxygen, such as the sulphites, protomuriate of tin, and the alkaline hydro- sulphurets, two volumes of it are converted into one volume of the protoxide. We see here, that when one prime of oxygen is abstracted, the remaining one enters into a denser state of union with azote. For the habitudes of this gas with hydro- gen, see AMMONIA; and with oxygen, see EUDIOMETER, and NITRIC and NITROUS ACIDS. Azote combines with chlorine and iodine to form two very formidable compounds : 1. The chloride of azote was discovered about the beginning of 1812, by M, Dulong; but its nature was first investigated and ascer- tained by Sir H. Davy. Put into an evaporating porcelain basin a solution of one part of nitrate or muriate of ammonia hi 10 of water, heated to about 100, and invert into it a wide-mouthed bottle filled with chlorine. As the liquid ascends by the condensation of the gas, oily-looking drops are seen floating on its surface, which collect to- gether, and fall to the bottom in large globules. This is chloride of azote. By putting a thin stratum of common salt into the bottom of the basia, we prevent the decomposition of the chloride of azote, by the ammoniacal salt. It should be formed only in very small quantities. The chloride of azote thus obtained is an oily- looking liquid ; of a yellow colour ; and a very pungent intolerable odour, similar to that of chlorocarbonous acid. Its sp. gr. is 1-653. When tepid water is poured into a glass con- taining it, it expands into a volume of elastic fluid, of an orange colour, which diminishes as it passes through the water. 44 I attempted," says Sir H. Davy, " to collect the products of the explosion of the new substance, by applying the heat of a spirit-lamp to a globule of it, confined in a curved glass tube over water : a little gas was at first extricated ; but long before the water had attained the temperature of ebullition, a violent flash of light was perceived, with a sharp report ; the tube and glass were broken into small fragments, and I received a severe wound in the transparent cornea of the eye, which has produced a considerable inflamma- tion of the eye, and obliges me to make this NIT NIT communication by an amanuensis. This ex- periment proves what extreme caution is ne- cessary in operating on this substance, for the quantity I used was scarcely as large as a grain of mustajd-seed." Phil. Trans. 1813, part I. It evaporates pretty rapidly in the air ; and in vacuo it expands into a vapour, which still possesses the power of exploding by heat. When it is cooled artificially in water, or the ammoniacal solution, to 40 F., the surrounding fluid congeals ; but when alone, it may be surrounded with a mixture of ice and muriate of lime, without freezing. It gradually disappears in water, producing azote ; while the water becomes acid, acquiring the taste and smell of a weak solution of nitro- muriatic acid. With muriatic and nitric acids, it yields azote ; and with dilute sulphuric acid, a mixture of azote and oxygen. In strong so- lutions of ammonia it detonates ; with weak ones, it affords azote. When it was exposed to pure mercury, out of the contact of water, a white powder (calomel) and azote were the results. " The action of mercury on the compound," says Sir H. " appeared to offer a more correct and less dangerous mode of attempting its analysis ; but on introducing two grains under a glass tube filled with mercury, and inverted, a violent detonation occurred, by which I was slightly wounded in the head and hands, and should have been severely wounded, had not my eyes and face been defended by a plate of glass, attached to a proper cap j a precaution very necessary in all investigations of this body."_Phil. Trans. 1813, part II. In using smaller quantities, and recently distilled mer- cury, he obtained the results of the experiments, without any violence of action. From his admirable experiments on the analysis of this formidable substance, by mer- cury, by muriatic acid, and from the discolora- tion of sulphate of indigo, we may infer its composition to be 4 vol. of chlorine rz 10 4 primes 18-0 1 of azote = 0.9722 I 1-75 or very nearly 10 by weight of chlorine to 1 of azote. A small globule of it thrown into a glass of olive oil, produced a most violent explosion ; and the glass, though strong, was broken into fragments. Similar effects were produced by its action on oil of turpentine and naphtha. When it was thrown into ether or alcohol, there was a very slight action. When a par- ticle of it was touched under water by a particle of phosphorus, a brilliant light was perceived under the water, and permanent gas was dis- engaged, having the characters of azote. When quantities larger than a grain of mustard-seed were used for the contact with phosphorus, the explosion was always so violent as to break the vessel in which the experiment was made. On tinfoil and zinc it exerted no action ; nor on sulphur and resin. But it de- tonated most violently when thrown into a solution of phosphorus in ether or alcohol. The mechanical force of this compound in detonation, seems superior to that of any other known, not even excepting the ammoniacal fulminating silver. The velocity of its action appears to be likewise greater. I touched a minute globule of it, in a platina spoon resting on a table, with a fragment of phos- phorus at the point of a penknife. The blade was instantly shivered into fragments by the explosion. Messrs. Porrett, Wilson, and Rupert Kirk, brought 125 different substances in contact with it. The following were the only ones which caused it to explode : Supersulphuretted hydrogen. Phosphorus. Phosphuret of lime Phosphuretted camphor. Camphoretted oil. Phosphuretted hydrogen gas. Caoutchouc. Myrrh. Palm oil. Ambergris. Whale oil. Linseed oil. Olive oil. Sulphuretted oil. Oil of turpentine. tar. amber. petroleum. orange peel. Naphtha. Soap of silver. mercury. copper. lead. manganese. Fused potash. Aqueous ammonia. Nitrous gas. Nidi. Journ. vol. 34. 2. Iodide of azote. Azote does not combine directly with iodine. We obtain the com- bination only by means of ammonia. It was discovered by M. Courtois, and carefully ex- amined by M. Colin. When ammoniacal gas is passed over iodine, a viscid shining liquid is immediately formed of a brownish -black colour, which, in proportion as it is saturated with ammonia, loses its lustre and viscosity. No gas is disengaged during the formation of this liquid, which may be called iodide of am- monia. It is not fulminating. When dis- solved in water, a part of the ammonia is de- composed ; its hydrogen forms hydriodic acid ; and its azote combines with a portion of the iodine, and forms the fulminating powder. We may obtain the iodide of azote directly, by putting pulverulent iodine into common water of ammonia. This indeed is the best NIT NUX way of preparing it ; for the water is not de- composed, and seems to concur in the pro- duction of this iodide, only by determining the formation of hydriodate of ammonia. The iodide of azote is pulverulent, and of a brownish-black colour. It detonates from the smallest shock, and from heat, with a feeble violet vapour. When properly prepared, it often detonates spontaneously. Hence, after the black powder is formed, and the liquid ammonia decanted off, we must leave the capsule containing it in perfect repose. When this iodide is put into potash water, azote is disengaged, and the same products are obtained as when iodine is dissolved in that alkaline lixivium. The hydriodate of ammonia, which has the property of dissolv- ing a great deal of iodine, gradually decom- poses the fulminating powder, while azote is set at liberty. Water itself has this property, though in a much lower degree. As the ele- ments of iodide of azote are so feebly united, it ought to be prepared with great precautions, and should not be preserved. In the act of transferring a little of it from a platina capsule to a piece of paper, the whole exploded in my hands, though the friction of the particles on each other was inappreciably small. Both Sir H. Davy and M. Gay Lussac have exploded their iodide in glass tubes, and collected the results. The latter states, " that if we decompose a gramme (15-444 grains) of the fulminating powder, we obtain, at the temperature of 32, and under the pressure of 30 inches of naercury, a gaseous mixture amounting to 0-1152 litre, (7-03 cubic inches), and composed of 0-0864 of the vapour of iodine, and 0-0288 of azote." Ann. de Chim. xci. Now 0-0864 is to 0.0288 as 3 to 1 exactly. Therefore the detonating powder consists of 3 vols. of the va. of iod. = 8-63 X 3= 25-89 1 vol. of azote = = 0-9722 or reduced to the oxygen equivalent scale, it consists of 3 primes of iodine = 46-5 96-37 1 azote = 1-75 3-63 100-00 Azote has hitherto resisted all attempts to decompose it. Sir H. Davy volatilized the highly combustible metal potassium in azote over mercury, and passed the voltaic flame of 2000 double plates through the vapour; but the azote underwent no change. He made also many other attempts to decompose it, but they were unsuccessful. In my experiments on the ammoniacal salts, I found, that when dry lime and muriate of ammonia were ignited together in a Reaumur porcelain tube, connected with water in a Woolfe's apparatus, a portion of ammonia constantly disappeared, or was annihilated, while nothing but water was obtained to re- place that loss. " Of the tightness of the apparatus I am well assured. Indeed, I have performed the experiment with a continuous glass tube, sealed and bent down at one end like a retort, while the other end was drawn into a small tube, which passed under a jar on the mercurial pneumatic shelf. The middle part was kept horizontal, and artificially cooled. The sealed end contained the mixture of lime and sal ammoniac. A brush flame of a large alcohol blowpipe was made to play very gently on the end of the tube at first, but afterwards so powerfully, as to keep it ignited for some time. The sal ammoniac recovered did not exceed three-fourths of that originally em- ployed." The sal ammoniac was regenerated by saturating the ammonia with muriatic acid, and cautious evaporation. See Ann. of Phil. September, 1817. The strongest arguments for the compound nature of azote are derived from its slight ten- dency to combination, and from its being found abundantly in the organs of animals which feed on substances that do not contain it. Its uses in the economy of the globe are little understood. This is likewise favourable to the idea that its real chemical nature is as yet unknown, and leads to the hope of its being decomposable. It would appear that the atmospheric azote and oxygen spontaneously combine in other proportions, under certain circumstances, in natural operations. Thus we find, that mild calcareous or alkaline matter favours the forma- tion of nitric acid in certain regions of the earth ; and that they are essential to its pro- duction in our artificial arrangements for forming nitre from decomposing animal and vegetable substances. NITROUS ACID. See ACID (NITROUS). NOBLE METALS. This absurd name has been bestowed on the perfect metals, gold, silver, and platina. NUCLEUS OF CRYSTALS. See CRYS- TALLIZATION. NOVACULITE. WHETSLATE. NUX VOMICA. See STRYCHNIA. Oil. Oil o OBSIDIAN. Of this mineral 'there are two kinds, the translucent and transparent. 1. Translucent obsidian. Colour velvet- black. Massive. Specular splendent. Frac- ture perfect conchoidal. Translucent, or trans- lucent on the edges. Hard. Very brittle. Easily frangible. Streak gray. Sp. gr. 2-37 It melts, or becomes spongy before the blow- pipe. Its constituents are, silica 78, alumina 10, lime 1, soda 1.6, potash 6, oxide of iron 1. Vauq. It occurs in beds in porphyry, and various secondary trap rocks in Iceland and Tokay. 2. Transparent. Colour duck blue. Mas- sive and in brown grains. Splendent. Frac- ture perfect conchoidal. Perfectly transparent. Hard. Brittle. Sp. gr. 2-36. It melts more easily than the translucent obsidian, and into a white muddy glass. Its constituents are, silica 81, alumina 0-5, lime 0.33, oxide of iron 0-60, potash 2-7, soda 4. 5, water 0-5. Klap- roth. It occurs imbedded in pearl-stone por- phyry. It is found at Marekan, near Ochotsk in Siberia, and in the Serro de las Novajas in Mexico. OCHRE. An ore of iron. OCHROITS. Cerite. OCTOHEDRITE. Pyramidal titanium ore. ODOUR. The emanation of an odorife- rous body is generally ascribed to a portion of the body itself, converted into vapour. M. Robiquet, from a series of experiments pub- lished in theAnnalcs de Chimie et de Physique, xv. 27. thinks, that in many cases the odour is owing, not to the substance itself, but to a gas or vapour resulting from its combination with an appropriate vehicle, capable of dif- fusion in space. OETITES. Clay ironstone. OIL OF VITRIOL. See ACID (SUL- PHURIC). OIL. The distinctive characters of oil are inflammability, insolubility in water, and fluidity, at least in a moderate temperature. Oils are distinguished into fixed or fat oils, which do not rise in distillation at the tem- perature of boiling water ; and volatile or es- sential oils, which do rise at that temperature with water, or under 320 by themselves. The volatile oil obtained by attenuating animal oil, by a number of successive distilla- tions, is called Dippel's animal oil. Monnet asserts, that, by mixing acids with animal oil, their rectification may be very much facilitated. The addition of a little ether, before re- distillation of old essential oils, improves the flavour of the product. See ELAIN and ACID (OLEIC). m Fixed oils differ greatly in their specific gravities, as appears from the following table :- Cacoa, 0-892 Rape-seed, 0-913 Olives, 0-913 Ben, 0-917 Beech-nut, 0-923 Walnuts, 0-923 to 0-947 Almonds, 0-932 Linseed, 0-939 Poppies, 0-939 Hazel-nuts, 0-941 Oil of palm, 0-9G8 MM. Gay Lussac and Thenard analyzed olive oil in 1808, by igniting a determinate quantity of it, mixed with chlorate of potash, and ascertaining the products : they found it to consist of Carbon, 77-213 Hydrogen, 13-360 Oxygen, 9-427 100-000 Or, Carbon, 77-213 Ox. and hydr. in the pro-) 1 9.719 portions for forming water, ) *' Hydrogen excess, 12-075 Spermaceti oil by my analysis consists in 100 parts of carbon 78-91, hydrogen 10-97, oxygen 10-12, or Carbon, 10 atoms 7-5 78-0 Hydrogen, 8 do. 1- 11-5 Oxygen, 1 do. 1-000 10-5 100-0 In other terms 9 atoms olefiant gas, 1 carbonic oxide, and 1 carbon. Oil of turpentine gave me in analysis, carbon 82-51, hydrogen 9-62, oxygen 7-87; Or Carbon, 14 atoms 105 82-35 Hydrogen, 10 do. 1.25 9-80 Oxygen, 1 do. 1-00 7-85 Phil. Trans. 1822- Vauquelin has shown that volatile oils, as oil of lavender, absorb pure acetic acid in very large quantities, the greater part of which they give up to water by agitation with it. Oil of turpentine combines largely with alcohol, forming a homogeneous body. This effect is produced by a solution of the alcohol in the oil ; for 1 part of alcohol cannot be supposed to dissolve 5 of oil. When that compound is long and repeatedly agitated with water, the whole alcohol cannot be separated ; about T ^ of the volume remaining combined, without' our being able to perceive it, if it be not by the specific gravity which is a little diminished. OIL 624 OIL By repeated lotions with much water the al- cohol may be all finally removed. Ann. de Chim. xix. 279. If the pernitrate of mercury, made by dis- solving 6 parts of mercury in 7' 5 parts of nitric acid, of sp.gr. 1-36 at common temperatures, be mixed with olive oil, in the course of a few hours the mixture, if kept cold, becomes solid ; but if mixed with the oil of grains, it does not solidify. M. Pontet proposes therefore this substance as a test of the purity or adulteration of olive oil ; for the resulting mixture, after standing 12 hours, is more or less solid, as the oil is more or less pure. The nature of the white, hard, and opaque mixture, formed by olive oil and the nitrate of mercury, has not been ascertained. See ACID (MAB.GARIC), ELAIK, and FAT. OIL OF AMBER. When amber is distilled in a retort, it yields about one-third its weight of a fetid brown oil, which is occasion- ally used as an antispasmodic in medicine. OIL GAS. It has been long known to chemists, that wax, oil, tallow, &c. when passed through ignited tubes, are resolved into combustible gaseous matter, which burns with a rich light. Messrs. Taylor and Martineau have availed themselves skilfully of this fact, and contrived an ingenious apparatus for ge- nerating oil gas on the great scale, as a substitute for candles, lamps, and coal gas. I shall insert, here, a brief account of their improvements. The advantages of oil gas, when contrasted with coal gas, are the following : The mate- rial from which it is produced containing no sulphur or other matter by which the gas is contaminated, there are no objections to its use on account of the suffocating smell in close rooms. It does no sort of injury to furniture, books, plate, pictures, paint, &c. All the costly and offensive operation of purifying the gas by lime, &c. is totally avoided when it is obtained from oil. Nothing is contained in oil gas which can possibly injure the metal of which the conveyance pipes are made. The economy of light from oil gas may be judged from the following table : Argand burner oil gas, per hour, . f d. Argand lamps spermaceti oil, ' 3d. Mould candles, .... 3^d. Wax candles, .... Ud. The oil gas has a material advantage over coal gas, from its peculiar richness in olefiant gas, which renders so small a volume neces- sary, that one cube foot of oil gas will be found to go as far as four of coal gas. This circumstance is of great importance, as it reduces in the same proportion the size of the gasometers which are necessary to contain it : this is not only a great saving of expense in the construction, but is a material convenience where room is limited. In the .course of their first experiments, Messrs. John and Philip Taylor were surprised to find, that the apparatus they employed gradually lost its power of decomposing oil, and generating gas. On investigation they discovered, that the metallic retorts which had originally decomposed oil and produced gas in abundance, ceased in a very great degree to possess this power, although no visible change had taken place in them. The most perfect cleaning of the interior of the retort did not restore the effect, and some alteration appears to be produced on the iron by the action of the oil, at a high temperature. Fortunately the experiments on this subject led to a most favourable result, for it was found, that by introducing fragments of brick into the retorts, a great increase of the decom- posing power was obtained, and the apparatus has been much improved by a circumstance which at one time appeared to threaten its success. A small portion of the oil introduced into the retort still passed off undecomposed, and being changed into a volatile oil, it carried with it a great portion of caloric, which ren- dered the construction of the apparatus more difficult than was at first anticipated ; but by the present arrangement of its parts, this difficulty is fully provided for, and the vola- tilized oil is made to return into the oil re- servoir, from whence it again passes into the retort, so that a total conversion of the whole into gas is accomplished without trouble, or the escape of any unpleasant smell. A general idea of the process may be formed from the following account of it : A quantity of oil is placed in an air-tight vessel, in such a manner that it may flow into retorts which are kept at a moderate red heat ; and in such proportions as may regulate the production of gas to a convenient rate ; and it is provided, that this rate may be easily governed at the will of the operator. The oil, in its passage through the retorts, is principally decomposed, and converted into gas proper for illumination, having the great advantages of being pure and free from sul- phurous contamination, and of supporting a very brilliant flame, with the expenditure of very small quantities. As a further precaution to purify the gas from oil, which may be suspended in it in the state of vapour, it is conveyed into a wash vessel, where, by bubbling through water, it is further cooled and rendered fit for use ; and passes by a proper pipe into a gasometer, from which it is suffered to branch off in pipes in the usual manner. The oil gas which I have been accustomed to make has only a double illuminating power, compared to good coal gas. See a drawing of an elegant apparatus, erected by Messrs. P. and M. at the Apothecaries' Hall, London, in OIL G25 OLE the 15th Number of the Journal of Science and the Arts. When the gaseous matter obtained by the igneous decomposition of oil is compressed to about one-thirtieth of its volume, as by the portablegas company, a certain new liquid com- pound results. This fluid is colourless or opa- lescent, yellow by transmitted, green by reflected light, of a specific gravity less than water, insoluble in water unless in very minute quan- tities, soluble in alcohol, ether, oils, &c., and combustible, burning with a dense flame. It is well distinguished from the oil that afforded it, by being very slightly acted upon by al- kaline solutions. When the bottle containing it is opened, evaporation takes place from the surface of the liquid, as is obvious from the striae in the air. This vapour soon ceases, and the remainder is comparatively fixed. It has the smell of oil gas. Its specific gravity is 0-821. It does not solidify at F. It is neutral to test colours. Muriatic acid has no action on it. Sulphuric acid acts on it, in a peculiar manner. This fluid is a mixture of various bodies, which may, by their difference of volatility, be separated in some degree from each other. When the vessel containing it is opened, it begins to boil at 60 a F. As the more volatile portions are dissipated, the temperature rises ; and before a tenth part is thrown off, the tem- perature exceeds 100. The heat after this continues to rise, and before the substance is all dissipated, it becomes 25(1. A liquid distilled over, when the retort was at 176, became partly solid in the receiver, crystals forming round the side, and a fluid remaining in the centre ; while two other por- tions, one drawn off at 186 F., another at 190, became quite hard at F. This being dried by bibulous paper, introduced into it by a glass rod, did not become fluid until raised to 28 or 29 F. After being squeezed in a Bramah's press between folds of blotting paper, contained between plates cooled to 0, it was ultimately distilled off caustic lime, to separate any water it might'still contain. This substance is a bicarburet of hydrogen. It is, at ordinary temperatures, a transparent co- lourless liquid, having somewhat of the odour of almonds, and a specific gravity of 0-85 at 60. It crystallizes at 32. Its fusing point is more exactly 42\ It contracts very much on congealing, 9 parts in bulk becoming very nearly 8, when its density becomes 0.956. At 0, it appears as a white or transparent sub- stance, brittle, pulverulent, and of the hardness nearly of loaf sugar. It evaporates entirely when exposed to the air. Its boiling point is 186 in a glass vessel. The sp. gr. of its vapour, equated to a temperature of 60% is nearly 40 times that of hydrogen. It does not conduct electricity. When admitted to oxygen gas, so much vapour rises, as to constitute a powerfully detonating mixture. By transmis- sion through an ignited tube, it becomes carburetted hydrogen, with deposition of charcoal. Chlorine, aided by the sunbeam, combines with it, and triple compounds of chlorine, carbon, and hydrogen, result. Potas- sium is not affected by it, even at 186 F. Its constituents are, carbon 1 -5 -f- hydrogen 0-125. Another product from the distillation of the condensed oil-gas liquid, is that which is most volatile. It forms a liquid at 0, but is all resolved into gas at 32 F. This gas is very combustible. It is 28 times denser than hy- drogen. Its density, in the liquid state, is 0-627 at 54 ; taken by weighing some of it in a glass tube, hermetically sealed. It is, there- fore., the lightest of solids or liquids. Ore volume of the vapour consists of four volumes of hydrogen, combined with four of vapour of carbon ; which, on the hydrogen radix, gives for its density (4 X 1 ) -f (4 X 6) = 28. It is therefore the same as olefiant gas condensed into half its usual volume. The oil gas liquid is an excellent solvent of caoutchouc, sur- passing every other substance in this quality. Faraday. OIL OF WINE. This liquid is produced at a certain period, during the distillation of a mixture of sulphuric acid and alcohol, in the formation of ether. It is a perfectly neutral substance. When heated, it evolves combustible matter, and becomes highly acid ; the com- bustible matter is hydrocarbon. Upon exa- mining the acid thus produced, it is found to be the same with the sulphcvinic acid, and united with bases it forms sulphovinates. Oil of wine consists of 2 atoms of sulphuric acid, 8 of carbon, and 8 of hydrogen. It is neutral ; but, by heat, gives off half of the carbon and hydrogen, while sulphovinic acid remains, composed of 2 atoms of sulphuric acid, 4 of carbon, and 4 of hydrogen ; which elements, with an atom of any base, form sulphovinates. When oil of wine is mixed with a cold solution of muriate of barytes, no change takes place ; but if heat be applied to the mixture, sulphate of barytes precipitates. 38 per cent, of sulphuric acid is thus indicated in oil of wine ; the remaining 62 parts are carbon and hydrogen, in the same proportions as they exist in olefiant gas. Hennel. Phil. Trans., 1826. Part 3d. OISANITE. Pyramidal titaniunvore. OLEFIANT GAS. A compound of one prime of carbon and one of hydrogen, to which I have given the name of CARBU RET- TED HYDROGEN, to distinguish it from the gas resulting from one prime of carbon and two of hydrogen, which I have called sub- carburetted hydrogen. OLEIC ACID. See ACID (OLEIC). OLEOSACCHARUM. This name is given to a mixture of oil and sugar incorpo- rated with each other, to render the oil more easily diffusible in watery liquors. OLEUM VINI. See ETHER. s s OPA (126 OPI I OLIBANUM. A gum resin, the product of the Juniperus Lvcia, Linn., brought from Turkey and the East Indies, usually in drops or tears. The best is of a yellowish-white colour, solid, hard, and brittle : when chewed for a little time, it renders the spittle white, and impresses an unpleasant bitterish taste ; laid on burning coals, it yields an agreeable smell. OLIVENITE. An ore of copper. OLIVINE. A sub-species of prismatic chrysolite. Its colour is olive-green. It oc- curs massive and in roundish pieces. Rarely crystallized in imbedded rectangular four- sided prisms. Lustre shining. Cleavage im- perfect double. Fracture small-grained uneven. Translucent. Less hard than chrysolite. Brittle. Spec. grav. 3.24. With borax it melts into a dark green bead. It loses its colouring iron in nitric acid. Its constituents are, silica 50, magnesia 38.5, lime 0.25, oxide of iron 12. It occurs in basalt, greenstone, porphyry, and lava, and generally accom- panied with augite. It is found in the Lo- thians, Hebrides, north of Ireland, Iceland, France, Bohemia, &c. OLLARIS LAPIS. See POTSTONE. OMPHACITE. Colour pale leek-green. Massive, disseminated, and in narrow radiated concretions. Lustre glistening and resinous. Fracture fine-grained uneven. Feebly trans- lucent. A shard as felspar. Sp. gr. 3.3. It occurs in primitive rocks, with precious garnet, in Carinthia. It is a variety of augite. ONYX. Calcedony, in which there is an alternation of white, black, and dark-brown layers. OPACITY. The faculty of obstructing the passage of light. OPAL. A sub-species of the indivisible quartz of Mohs. Of opal there are seven kinds, according to Professor Jameson. 1. Precious opal. Colour milk-white, in- clining to blue. It exhibits a beautiful play of many colours. Massive, disseminated, in plates and veins. Lustre splendent. Fracture perfect conchoidal. Translucent, or semi- transparent. Semi-hard in a high degree. Brittle. Uncommonly easily frangible. Sp. gr. 2-1. Before the blowpipe it whitens and becomes opaque, but does not fuse. Its con- stituents are, silica 90, water 10. It occurs in small veins in clay porphyry, with semi- opal, at Czscherwenitza, in Upper Hungary ; and in trap rocks at Sandy Brae, in the north of Ireland. Some of them become transparent by immersion in water ; and are called oculus mundi, hydrophane, or changeable opal. 2. Common opal. Colour milk-white. Massive, disseminated, and in angular pieces. Lustre splendent. Fracture perfect conchoidal. Semitransparent. Scratches glass. Brittle. Adheres to the tongue. Infusible. Its con- stituents are, silica 93-5, oxide of iron 1, water &-~Klaproth. It occurs in veins along with precious opal in clay porphyry, and in metal- liferous veins in Cornwall, Iceland, and the north of Ireland. 3. Fire opal. Colour hyacinth-red. Lustre splendent. In distinct concretions. Fracture perfect conchoidal. Completely transparent. Hard. Uncommonly easily frangible. Sp. gr. 2.12. Heat changes the colour to pale flesh-red. Its constituents are, silica 92, water 7 '75, iron 0.25. It has been found only at Zimapan in Mexico, in a particular variety of hornstone porphyry. 4. Mother-of-pearl opal, or Cacholong. It is described under C AC HO LONG, as a variety of calcedony. 5. Semi-opal. Colours white, gray, and brown ; sometimes in spotted, striped, or clouded delineations. Massive, disseminated, and in imitative shapes. Lustre glistening. Fracture conchoidal. Translucent. Semi- hard. Rather easily frangible. Sp. gr. 2-0. Infusible. Its constituents are, silica 85, alumina 3, oxide of iron l.7*>, carbon 5, am- moniacal water 8, bituminous oi!0^33 Klap. roth. It occurs in porphyry and amygdaloid, in Greenland, Iceland, and Scotland, in the Isle of Rume, &c. 6. Jasper opal, or Fcrrtiginotis opal. Co- lour scarlet-red, and gray. Massive. Lustre shining. Fracture perfect conchoidal. Opaque. Between hard and semi-hard. Easily frangible. Sp. gr. 2-0. Infusible. Its constituents are, silica 43 5, oxide of iron 47-0, water 7-5 Klaproth. It is found in porphyry at Tokay in Hungary. 7. Wood opal. Colours very various. In branched pieces and stems. Lustre shining. Fracture conchoidal. Translucent. Semi-hard in a high degree. Easily frangible. Sp. gr. 2-1. It is found in alluvial land at Zastravia in Hungary. OPIUM. See MORPHIA, and ACID (MECONIC). In the 8th and 9th volumes of the Journal of Science, and in the 1 st of the Edinburgh Phil. Journal, are two valuable papers on the manufacture of British opium ; the first by the Rev. Gr. Swayne, the second by Mr. Young. The manufacture of Indian opium has been of late years greatly improved by Dr. Fleming, M. P., under whose superintendence that important department was placed by the Marquis of Wellesley. According to Orfila, a dangerous dose of opium is rather aggravated than counteracted by vinegar. The proper remedy is a powerful emetic, such as sulphate of zinc, or sulphate of copper. See an interesting and well treated case, in the 1st volume of the Medico- Chirurgical Trans, by Dr. Marcet and Mr. Astley Cooper. The experiments of M. Magendie have shown that the salt extracted long ago from opium by Derosnes, and which has been called narcotine, produces a stupor differing from real ORE 627 ORE sleep, and acts on dogs as a poison in srhall doses. This nurcotlne may be separated, by sulphuric ether, from the strained watery ex- tract of opium. The ether afterwards deposits the narcotine in crystals ; while the residuary opium is supposed to be better fitted than before, for procuring tranquil sleep. OPOBALSAM. The most precious of the balsams is that commonly called Balm of Gilead, Opobalsamum, Balsamaslon, Bal- samum verum album, ^Egyptiacum, Judai- cum, Syriacum, e Mecca, &c. This is the produce of the amyris opobalsamum, L. The true balsam is of a pale yellowish colour, clear and transparent, about the con- sistence of Venice turpentine, of a strong, penetrating, agreeable, aromatic smell, and a slightly bitterish pungent taste. By age it becomes yellower, browner, and thicker, losing by degrees, like volatile oils, some of its finer and more subtile parts. To spread, when dropped into water, all over the surface, and to form a fine, thin, rainbow-coloured cuticle, so tenacious that it may be taken up entire by the point of a needle, were formerly infallible criteria of the genuine opobalsam. Neumann, however, had observed, that other balsams, when of a certain degree of consistence, exhibit these phenomena equally with the Egyptian. According to Bruce, if dropped on a woollen cloth, in its pure and fresh state, it may be washed out completely and readily with simple water. OPODELDOC. A solution of soap in alcohol, with the addition of camphor and volatile oils. It is used externally against rheumatic pains, sprains, bruises, and other like complaints. OPOPANAX. A concrete gummy re- sinous juice, obtained from the roots of an umbelliferous plant, the pastinaca opopanax, Linn. 9 which grows spontaneously in the warmer countries, and bears the colds of this. The juice is brought from Turkey and the East Indies, sometimes in round drops or tears, but more commonly in irregular lumps, of a reddish-yellow colour on the outside, with specks of white ; inwardly of a paler colour, and frequently variegated with large white pieces. It has a peculiar strong smell, and a bitter, acrid, somewhat nauseous taste. ORES. The mineral bodies from which metals are extracted. I. ANTIMONY, Ores of. I. Native antimony, of which there are two species ; dodecahedral, and octohedral. 1. Dodecahedral. Colour tin-white. Mas. sive and crystallized in an octohedron and do- decahedron. Harder than calcareous spar. Sp. gr. 6.7. It consists of 98 antimony, 1.0 silver, and 0.25 iron. It is found in argenti- ferous veins in the gneiss mountains of Cha- lanches in Dauphiny, and at Andreasberg in the Hartz. 2. Octohedral antimony; of which there are two sub-species, the antimonial silver, and arsenical silver. See ORES or SILVER. II. ANTIMONY GLANCE. Under this genus are ranged the following species, sub- species, and kinds. J . Compact gray antimony. Colour light lead-gray. Massive. Soft. Easily frangible. Sp. gr. 4.4. Found in Huel Boys mine in Cornwall. 2. Foliated gray antimony. Colour like the preceding. Cleavage prismatic. Not particularly brittle. Sp. gr. 4.4. 3. Radiated gray antimony. Colour com- mon lead-gray. Massive, and crystallized in four and six-sided prisms, and sometimes in acicular crystals. Lustre metallic. Sp. gr. 4.4. It melts by the flame of a candle. Its constituents are, antimony 75, sulphur 25. These minerals occur in veins, in primitive and transition mountains. This occurs in Glen- dinning in Dumfriesshire, in Cornwall, &c. 4. Plumose gray antimony. Colour be- tween dark lead-gray and smoke-gray. Mas- sive, and in capillary glistening crystals. Lus- tre semi-metallic. Very soft. It melts into a black slag. It contains antimony, sulphur, arsenic, iron, and silver. It occurs in veins in primitive rocks, at Andreasberg in the Hartz, &c. 5. Axifrangible antimony glance or Bourno- nite. Colour blackish lead-gray. Massive and crystallized. Primitive form, an oblique four-sided prism, which occurs variously mo- dified by truncation, &c. Lustre metallic. Cleavage axifrangible. Fracture conchoidal. Brittle. Sp. gr. 5.7- Its constituents are, lead 42.62, antimony 24.23, copper 12.8, iron 1.2, sulphur 17. Hatchett. It is found near Endellion in Cornwall. 6. Prismatic antimony glance. Colour blackish lead-gray. Primitive form, an ob- lique four-sided prism. Lustre metallic. Cleavage in the direction of the smaller dia- gonal of the prism. Sp. gr. 5.75. III. Antimony ochre. Colour straw-yellow, incrusting crystals of gray antimony. Dull. Fracture earthy. Very soft. Brittle. Whitens and evaporates before the blowpipe. It occurs in veins in Saxony, &c. IV. Nickelifcrous gray antimony. Colour steel-gray. Massive. Shining. Cleavage dou- ble rectangular. Fragments cubical. Brittle. Sp. gr. 6 to 6.7. It melts before the blow- pipe, emitting white vapour of arsenic. It communicates a green colour to nitric acid. It consists of antimony with arsenic 61.68, nickel 23.33, sulphur 14.16, silica, with silver and lead, 0.83, and a trace of iron. It occurs in veins near Fruesberg in Nassau. V. Prismatic white antimony. Colour white. Massive and crystallized, in a rectan- gular four-sided prism, an oblique four-sided prism, a rectangular four-sided table, a six- s s 2 ORE 628 ORE sided prism, and in acicular and capillary crys- tals. Lustre pearly or adamantine. Cleav- age in the direction of the lateral planes. Translucent. Sectile. Sp. gr. 5.0 to 5.C. It melts and volatilizes in a white vapour. I is constituents are, oxide of antimony 86, oxides of antimony and iron 3, silica 8. it occurs in veins in primitive rocks ill Bohemia and Hungary. VI. Prismatic antimony-blende, or red an- timony. a. Common. Colour cherry-red. Massive, in flakes, and crystallized. Primitive form, an oblique four-sided prism. Crystals delicate capillary. Adamantine. Translucent on the edges. Brittle. Sp. gr. 4.5 to 4.6. It melts and evaporates before the blowpipe. It con- sists of antimony 67.5, oxygen 10.8. sulphur 19-7 Klapr. It occurs at Braunsdorf in Saxony. b. Tinder antimony' blende. Colour muddy cherry-r^d. In flexible tinder-like leaves. Feebly glimmering. Opaque. Streak shin- ing. Friable. Sectile and flexible. It con- tains oxide of antimony 33, oxide of iron 40, oxide of lead 16, sulphur 4, with some silver. Link. It occurs in the Carolina and Do- rothea mines at Clausthal. II. ARSENIC. 1. Native arsenic. Fresh fracture, whitish lead-gray. Massive, and in imitative shapes. Feebly glimmering. Harder than calcareous spar. Streak shining, metallic. When struck, it has a ringing sound, and emits an arsenical odour. Sp. gr. 5.75. It occurs in veins in primitive rocks, at Kongsberg in Norway, &c. 2. Oxide of arsenic ; common, capillary, and earthy. a. Common oxide has a white colour ; oc- curs in crystalline crusts ; has a shining lustre ; uneven fracture ; and is soft and semitrans- parent. b. The capillary occurs in silky, snow-white, shining, capillary crystals. c. The earthy is yellowish -white ; in crusts. Dull, opaque, and friable. It occurs at An- dreasberg in the Hartz. 3. Arsenical pyrites. a. Common arsenical pyrites. Mistpickel. Fresh fracture silver-white. Massive and in prismatic concretions. Crystallized in oblique four-sided prisms. Lustre splendent metallic. Fracture coarse-grained. Cleavage in the di- rection of the perpendicular prism. Sometimes as hard as felspar. Brittle. It emits an ar- senical smell on friction. Sp. gr. 5.7 to 6.2. Before the blowpipe it yields a copious arsenical vapour. Its constituents are, arsenic 43.4, iron 34.9, sulphur 20.1. It occurs in primitive rocks, in Cornwall and Devonshire, and at Alva in Stirlingshire. b. Argentiferous arsenical pyrites. Colour silver-white. Disseminated, and in very small acicular, oblique, four-sided prisms. Shining and metallic. Besides arsenic and iron, it contains from 0.01 to 0.10 of silver. It has been found in Saxony ; and is used as an ore of silver. 4. Pliarmacolite, or arsenic-bloom. Colour reddish-white. As a coating of balls, or in delicate capillary shining silky crystals. Semi- transparent, or opaque. Soft. Soils. Sp. gr. 2.04. Its constituents are, lime 25, arsenic acid 50.44, water 24.56. It occurs in veins along with tin-white cobalt at Andreasberg, &c. 5. Orpiment. a. Red ; ruby sulphur, or hcmi-prhmatic sulphur. Colour aurora-red ; massive ; in flakes, and crystallized in oblique four-sided prisms. Lustre inclining to adamantine. Frac- ture uneven. Translucent. Streak orange- yellow coloured. As hard as talc. Brittle. Sp. gr. 3.35. It melts and burns with a blue flame. It is idio-clectric by friction. Its constituents are, arsenic 69, sulphur 31. It occurs in primitive rocks at Andreasberg, &c. b. Yellow orpiment, or prismatoidal sul- phur. Colour perfect lemon-yellow. Mas- sive, imitative, arid crystallised in oblique four-sided prisms, and in flat double four- sided pyramids. Cleavage prismatoidal. Translucent. Harder than the red. Flexible, but not elastic. Splits easily. Sp. gr. 3.5. Its constituents are, arsenic 62, sulphur 38. It occurs in veins in floetz rocks ; and along with red silver in granite at Wiltichen in Swabia. III. BISMUTH. 1. Native or octahedral bismuth. Fresh fracture silver-white, inclining to red. Mas- sive and crystallized in an octohedmn, tetra- hedron, and cube. Lustre splendent, metal- lic. Cleavage fourfold. Harder than gypsum. Malleable. Sp. gr. 8.9 to 9.0. It melts by the flame of a candle. It occurs in veins in mica-slate, &c. at St. Columb and Botailack, in Cornwall; and in Saxony. 2. Bismuth-glance. a. Acicular bismuth -glance. Colour dark lead-gray. Disseminated, and crystallized in oblique four or six-sided prisms. Lustre splendent, metallic. Fracture uneven. Opaque. Brittle. Sp. gr. 6.1 to 6.2. It fuses before the blowpipe into a steel-gray globule. Its constituents are, bismuth 43.2, lead 24.32, copper 12.1, sulphur 11.58, nickel 1.58, tel- lurium 1.32, gold 0.79. It occurs embedded in quartz near Bcresof in Siberia. It is also called needle ore. b. Prismatic bismuth glance. Colour pale lead-gray. Massive, and crystallized in aci- cular and capillary oblique four and six-sided prisms. Lustre splendent, metallic. It soils ; is brittle ; and harder than gypsum. Sp. gr. 6.1 to 6.4. It melts in the flame of a candle. Its constituents are, bismuth 60, sulphur 40. It occurs in veins in Cornwall, &c. ORE 629 ORE n. Cupreous bismuth. Colour light lead- gray. Massive. Shining. Sectile. Its con- stituents are, bismuth 47.24, copper 34.66, sulphur 12.58. It occurs in veins in granite near Wittichen in Furstemberg. b. Bismuth ochre. Colour straw-yellow. Massive. Lustre inclines to adamantine. Opaque. Soft. Brittle. Sp. gr. 4.37. It dissolves with effervescence in acids. Its con- stituents are, oxide of bismuth 86.3, oxide of iron 5.2, carbonic acid 4.1, water 3.4. It oc- curs along with red cobalt. It is found at St. Agnes in Cornwall. IV. CERIUM. See ALLANITE, CE- RITE, GADOLIXITE, ORTHITE, YTTRO- CERITE. A fluate and subfluate of cerium have been also discovered at Finbo in Sweden. V. COBALT ORES. 1. Hcxtihedral cobalt pyrites, or silver '- 'white cobalt. Colour silver- white. Massive, and crystallized in the cube, octohcdron, cube truncated, pentagonal, dodecahedron, icosa- hedron. Splimdent, and metallic. Cleavage hexahedral. Fracture conchoidal. Semi-hard. Brittle. Streak gray. Sp. gr. 6.1 to 6.3. Before the blowpipe it gives out an arsenical odour ; and, after being roasted, colours glass of borax smalt blue. Its constituents are, cobalt 44, arsenic 55, sulphur 0.5. Iron is sometimes present. It occurs in primitive rocks at Skutterend, in Norway. It is the principal ore of cobalt. 2. Octahedral cobalt pyrites. a. The tin-white ; of which there is the compact and radiated. The compact has a tin-white, and sometimes rather dark colour. It occurs massive and crystallized in the cube, ootohedron, and rhomboidal dodecahedron, truncated on the six four-edged angles. Crys- tals generally rent and cracked.. Lustre splen- dent, metallic. Brittlo. Sp. gr. 6.0 to 6.6. Its constituents are, arsenic 74.22, cobalt 20.3, iron 3.42, copper 0.16, sulphur 0.89. It oc- curs in granite, gneiss, &c. in Cornwall, Saxony, &c. The radiated; colour tin-white, inclining to gray. Massive, and in distinct radiated concretions. Lustreglistening, metallic. Softer than the compact. Its constituents are, arse- nic 65-75, cobalt 28, oxide of iron 5-0, oxide of manganese 1-25. It occurs in clay-slate at Schneeberg. b. Gray octahedral cobalt pyrites. Colour light steel-gray. Massive, and tubiform. Dull, and tarnished externally. Internally splend- ent metallic. Fracture even. Streak shining. Brittle. When struck, emits an arsenical odour. Sp.gr 6-135. It contains 19 6 of cobalt, with iron and arsenic. It occurs in granite, gneiss, &c. It is found in Cornwall, Norway, &c. It affords a more beautiful blue smalt than any of the other cobalt minerals. Cobalt-kies. Colour pale sleel gray. Mas- sive, and in cubes. Lustre metallic. Fracture uneven. Semi-hard. Its constituents arc, cobalt 43-2, sulphur 38-5, copper 14-4, iron 3-53. It occurs in a bed of gneiss in Sweden. 3. lied cobalt. a. Radiated red cobalt, or cobalt-bloom. Colour crimson-red, passing into peach-bios, som. Massive, imitative, and crystallized, in a rectangular four-sided prism, or a com- pressed acute double six-sided pyramid. Cry- stals acicular. Shining. Translucent. Ra- ther sectile. Sp. gr. 4-0 to 4-3. It tinges borax-glass blue. Its constituents are, cobalt 39, arsenic acid 38, water 23. It occurs in veins in primitive, transition, and secondary rocks. It is found at Alva in Stirlingshire, in Cornwall, &c. b. Earthy red cobalt, or cobalt crust. (Jo- lour peach-blossom red. Massive, and imi- tative. Friable. Dull. Sectile. Streak shin- ing. Does not soil. c. Slaggy red cobalt. Colour muddy crim- son red. In crusts and reniform. Smooth. Shining. Fracture conchoidal. Translucent. Soft and brittle. It occurs at Furstemberg. 4. Cobalt ochre. a. Black. The earthy-black has a dark brown colour ; is friable, has a shining streak, and feels meagre. The indurated black has a bluish-black colour ; occurs massive and imi- tative ; has a glimmering lustre : fine earthy fracture ; is opaque ; soft ; sectile ; soils ; sp. gr. 2 to 2-4. It consists of black oxide of cobalt, with arsenic and oxide of iron. These two sub-species occur usually together, in primitive or secondary mountains ; at Alderly Edge, Cheshire, in red sandstone ; at Howth, near Dublin, in slate-clay. b. Brown cobalt-ochre. Colour liver- brown. Massive. Dull. Fracture fine earthy. Opaque. Streak shining ; soft, sectile, light. It consists of brown ochre of cobalt, arsenic, and oxide of iron. It occurs chiefly in se- condary mountains. It is found at Kamsdorf in Saxony. c. Yellow cobalt-ochre. Colour muddy straw-yellow. Massive and incmsting. Rent. Dull. Fracture fine earthy- Streak sliming. Soft and sectile. Sp. gr. 2.67, after absorb- ing water. It is the purest of the cobalt, ochres. It is found with the preceding. It contains silver. 5. The sulphate of cobalt is found at Biber, jiear Hannau, in Germany. It consists of sulphuric acid 19-74, oxide of cobalt 38-71, water 41-55. It has a light fl.sh-rcd colour; and a stalactical form. Streak ycllowish- whUe. Taste styptic. VI. COPPER ORES. 1. Octahedral or native copper. Colour copper-red, frequently incmsted with green. Massive, imitative, and crystallized ; in the perfect cube ; the cube truncated, on the angles, on the edges, and on the edges and angles ; the garnet dodecahedron ; perfect octahedron ; and rectangular four-sided prism. Lustre glimmering, metallic. Fracture hack- ORE 630 ORE ly. Streak splendent, metallic. Harder than silver. Completely malleable. Flexible, but not elastic. Difficultly frangible. Sp. gr. 8-4 to 8-7- It consists of 99-8 of copper, with a trace of gold and iron. It occurs in veins, in granite, gneiss, &c. and is found chiefly in Cornwall. . 2. Octahedral red copper ore. a. Foliated red copper ore. Colour dark cochineal-red. Massive, and crystallized, in the perfect octohedron, which is the primitive form ; in the octohedron, truncated on the angles ; on the edges, with each angle acumi- nated with four planes ; bevelled on the edges, and each angle acuminated with eight planes. Lustre adamantine, inclining to semi-metallic. Cleavage fourfold. Translucent on the edges, or translucent. Streak muddy tile-red. Hard- ness between calcareous and fluor-spar. Brit- tle. Sp. gr. 5-6 to 6-0. .-,' b. Compact red copper ore. Colour be- twqen lead-gray and cochineal-red. Massive and reniform. Lustre semi-metallic. Frac- ture even. Opaque. Streak tile-red. Brittle. c Capillary red copper ore. Colour car- mine-red. In small capillary crystals. Lus- tre adamantine. Translucent. The whole of these red ores are deutoxides of copper, and are easily reduced to the me- tallic state before the blowpipe. They dis- solve with effervescence when thrown in pow- der into nitric acid ; and a green nitrate results. In muriatic acid no effervescence takes place. They occur principally in veins that traverse primitive and transition rocks ; abundantly in the granite of Cornwall. The earthy red cop- per ore, which is rare, is a sub-species of the preceding. d. Tile ore. The earthy tile ore has a hyacinth-red colour. It occurs massive and incrusting copper pyrites. It is composed of dull dusty particles. It soils slightly, and feels meagre. It occurs in veins, as at Lau- terberg in the Hartz. The indurated tile ore has an imperfect flat conchoidal fracture ; a streak feebly shining ; and is intermediate be- tween semi-hard and soft. It is an intimate combination of red copper ore and brown iron ochre, containing from 10 to 50 per cent, of copper. 3. Black copper, or Hack oxide of copper. Colour between bluish and brownish-black. It occurs massive, and thinly coating copper pyrites. It is eomposed of dull pasty parti- cles, which scarcely soil. Streak slightly shining. Before the blowpipe it emits a sul- phureous odour, melts into a slag, and com- municates a green colour to borax. It is said to be an oxide of copper with oxide of iron. It occurs at Carharrack and Tincroft mines, in Cornwall. 4. Emerald copper or dioptaxc. Colour emerald-green. It occurs only crystallized. The primitive form is a rhomboid of 123 58'. The only secondary form at present known is the equiangular six-sided prism. I ing pearly. Cleavage threefold. Lustre shin - Fracture small conchoidal. Translucent. A s hard as apatite. Brittle. Sp. gr. 3.3. It becomes a chesnut-brown before the blowpipe, and tinges the flame green, but is infusible ; with borax it gives a bead of copper. Its consti- tuents are, oxide of copper 28-57, carbonate of lime 42-83, silica 28-5?. Vanq. By Lowitz, it consists of 55 oxide of copper, 33 silica, and 12 water, in 100. It is found in the land of Kirguise, 125 leagues from the Russian frontier, where it is associated with malachite and limestone. 5. Blue copper, or prismatic malachite, of which there are two kinds, the radiated and earthy. a. The radiated has an azure-blue colour. Massive, imitative, and crystallized. Its primitive form is an oblique prism. The secondary forms are, an oblique four-sided prism, variously bevelled, and a rectangu- lar four-sided prism, or eight-sided prism, acuminated with four planes. Lustre vi- treous. Cleavage threefold. Fracture im- perfect conchoidal. Translucent. Colour of the streak, lighter. Harder than calcareous spar. Brittle. Sp. gr. 3-65. It is soluble with effervescence in nitric acid. With borax it yields a metallic globule, and colours the flux green. Its constituents are, copper 56, carbonic acid 25, oxygen 12-5, water 6.5. Vauquelin. It is found at Leadhills in Dum- fries-shire, and Wanlockhead in Lanark- shire, and at Huel- Virgin and Carharrack in Cornwall, and in many places on the con- tinent. b. Earthy blue copper. Colour smalt-blue. Massive, Friable. Sp. gr. 3-354. It is found in Norway, &c. The velvet-blue copper belongs to the same species. Lustre glistening and pearly. It has been found only at Oravicza in the Ban- nat, along with malachite and the brown iron- stone. 6. Malachite ; of which there are, the fibrous and compact a. Fibrous malachite. Colour perfect eme- rald green. Imitative, and crystallized, in oblique four-sided prisms, variously bevelled or truncated; and in an acute-angular three- sided prism. Crystals short, capillary, and acicular. Lustre pearly or silky. Translu- cent, or opaque. Softer than blue copper. Streak pale green. Brittle. Sp. gr. 3-CC. Before the blowpipe it decrepitates, and be- comes black. Its constituents are, copper 58, carbonic acid 18, oxygen 12-5, water 11-5. Klaproth. It occurs principally in veins. It is found at Sandlodge in Mainland, one of the Shetlands ; at Landidno in Caernarvonshire ; and in the mines of Arendal in Norway. &. Compact malachite. Colour emerald- green. Massive, imitative, and in four-sided prisms. Glimmering and silky. Fracture ORE 631 ORE grained uneven. Opaque. Sireuk pale green. Sp. gr. 3-65. In veins, which tra- verse different rocks in Cornwall. Norway, c. Brown cojjj/er from Hindustan is placed after this mineral by Professor Jameson. Its colour is dark blackish-brown. Massive. Soft. Sp.gr. 2-62. It effervesces in acids, letting fall a red powder. Its constituents are, carbonic acid U-7, dcutoxide of copper GO-75, deutoxide of iron 19-5, silica 2-1. Dr. Thotnson. 7- Copper-green. Common copper green, or chrysocolla, con- tains three sub-species. Us CcHchoidal copper-green. Colour ver- digris-green. Massive, Imitative, and incrust- ing. Glistening. Fracture conchoidal. Trans- lucent. Harder than gypsum. Easily frangi- ble. Sp. gr. 2-0 to 2-2. It becomes black and then brown before the blowpipe, but does not fuse. It melts and yields a metallic glo- bule with borax. Its constituents are, copper 40, oxygen 10, carbonic acid 7, water 17> silica 26. Klaproth. It accompanies mala- chite. It is found in Cornwall, &c. Siliceous copper, or Icicsellcupfer, is a varie- ty of the above. Colour asparagus-green. In crusts. Glistening. Fracture even or earthy. Opaque. Soft. Its constituents are, copper 37.8, oxygen 8, water 21-8, silica 29, sulphate of iron 3. b. Earthy iron-shot copper-green. Colour olive-green. Massive, and in crusts. Friable. Opaque. Sectile. c. Sluggy iron-shot copper-green. Colour blackish-green. Massive. Glistening. Frac- ture conchoidal. Opaque. Soft. Easily fran- gible. It is probably a compound of conchoi- dal copper-green and oxide of iron. Both occur together, and pass into each other. It occurs in Cornwall, along with olivenite. 8. Prismatic vitriol, blue vitriol, or sul- phate of copper. Colour dark sky-blue. Mas- sive, imitative, and crystallized. The primi- tive figure is an oblique four -sided prism, in which the lateral edges are 124 2', and 55 58'; with edges and angles often truncated. Shining. Cleavage double. Fracture con- choidal. Translucent. Harder than gypsum. Sp. gr. 2-1 to 2-2. Taste nauseous, bitter, and metallic. Its solution coats iron with metallic copper. Its constituents are, oxide of copper 32-13, sulphuric acid 31-57, water 36-3. Berzelius. It occurs along with cop- per pyrites, in Pary's mine in Anglesea, and in 9. Prismatic olivenite, or phosphate of rtippct. Colour emerald-green. Massive, and in oblique four-sided prisms of 1 10. Cleav- age double oblique. Glistening. Fracture splintery. Opaque. Streak verdigris-green. As hard as apatite. Brittle. Sp. gr. 4 to 4-3. Fuses into a brownish globule. Its consti- tuents are, oxide of copper 68-13, phosphoric acid 30-95. It is found at Virceberg on the Rhine, along with quartz, red copper ore, &c. 10. Dipritmalic olivenite, or lenticular copper. Colour sky-blue. Massive, but ge- nerally crystallized. In very oblique four- sided prisms, bevelled; in rectangular double four-sided pyramids; shining; fracture un- even ; translucent. Harder than gypsum. Brittle. Sp. gr. 2-85. Converted by the blowpipe into a black friable scoria. Its constituents are, oxide of copper 49, arsenic acid 14, water 33,Chencvix. Found in Cornwall. Jl. Acicular olivenite. a. Radiated or cupreous arscniate of iron. , Colour dark verdigris-green. Massive, imitative, and in flat oblique four-sided prisms, acuminated or truncated. Lustre glistening pearly. Trans- lucent on the edges. As hard as calcareous spar. Brittle. Sp. gr. 3-4. 1. Foliated acicular olivenite ; arseniate of copper. Colour dark olive green. In an- gulo-granular concretions, and in small crys- tals; which are oblique four-sided prisms; and acute double four-sided pyramids. Glis- tening. Fracture conchoidal. Translucent. Streak olive-green. As hard as calcareous spar. Britele. Sp. gr. 4-2 to 4-0. It boils, and gives a hard reddish-brown scoria before the blowpipe. Its constituents are, oxide of copper CO, arsenic acid 39-7- Chenevix. In the copper mines of Cornwall. c. Fibrous acicular olivenite. Colour olive- green. Massive, reniform, and in capillary and acicular oblique four-sided prisms. Glis- tening and pearly. Opaque. As hard as calc- spar. Brittle. Fibres sometimes flexible. Streak brown or yellow. Sp. gr. 4-1 to 4-2. Its constituents are, oxide of copper 50, arsenic acid 29, water 21. It occurs in Cornwall. d. Earthy acicular olivenite. Colour olive- green. Massive and in crusts. Dull. Frac- ture fine earthy. Opaque. Very soft. It is found in Cornwall. 12. Atacamilc, or muriate of copper. a. Compact. Colour leek -green. Massive, and in short needle-shaped crystals, which are oblique four-sided prisms, bevelled or trun- cated. Shining and pearly. Translucent on the edges. Soft. Brittle. Sp. gr. 4.4 ? It tinges the flame of the blowpipe of a bright green and blue, muriatic acid rises in vapours, and a bead of copper remains on the charcoal. It dissolves without effervescence in nitric acid. Its constituents are, oxide of copper 73-0, water 1G-9, muriatic acid 10-1 Klap- ruth. It occurs in veins in Chili and Saxony. I). Arenaceous atacamitc, or copper-sand. Colour grass-green. In glistening scaly par- ticles. It does not soil. It is translucent. Its constituents are, oxide of eopper 63, water 12, muriatic acid 10, carbonate of iron 1, mixed siliceous sand 11. It is found in the sand of the river Lipes, 200 leagues beyond Copiapu, in the desert of Atacama, which separates Chili from Peru. 13. Copper pyrites. a. Octahedral copper pyrites. On the fresh fracture, its colour is brass-yellow ; but ORE 632 OltE it is usually tarnished. Massive, imitative, and crystallized ; in a regular octahedron, perfect, truncated or bi veiled ; and in a per- fect or truncated tetrahedron. Glistening. Fracture uneven. Hardness from calcareous to fluor spar. Brittle. Sp. gr. 4-1 to 4-2. Before the blowpipe, on charcoal, it decrepi- tates, emits a greenish-coloured sulphureous smoke, and melts into a black globule, which assumes metallic lustre. It tinges borax green. I*s constituents are, copper 30, iron 53, sulphur 12. Chenevix. It" contains sometimes a little gold or silver. It occurs in all the great classes of rocks. It is found near Tynedrum in Perthshire ; at the mines of Ec- ton ; at Pary's mountain ; abundantly in Cornwall ; and in the ccunty of Wicklow in Ireland. The rich ores are worked for cop- per ; the poor, for sulphur. I). Tetrahedral copper pyrites ; of which species there are two sub-species, gray copper and black copper. Gray copper. Colour steel-gray. Mas- sive and crystallized. In the tetrahedron, truncated or bevelled ; and in the rhomboidal dodecahedron. Splendent. Fracture uneven. Hardness as calcareous spar and fluor. Brit- tle. Sp. gr. 44 to 4-9. Its constituents are, copper 41, iron 22-5, sulphur 10, arsenic 24-1, silver 0-4 Klaproth. It occurs in beds and veins in Cornwall, and many other places. Black copper. Colour iron -black. Massive and crystallized; in the tetrahedron, perfect, bevelled, or truncated. Splendent. Fracture conchoidal. Brittle. Spsc. grav. 4.85. Its constituents are, copper 39, antimony 19.5, sulphur 2G, iron 7-5, mercury 6.25.-- Klaproth. The mercury is accidental. It occurs in veins in the Hartz, and in Peru. 14. White copper. Colour between silver- white and brass-yellow. Massive and disse- minated. Glistening and metallic. Fracture uneven. Semi-hard. Brittle. Spec. grav. 4.5. It yields before the blowpipe a white arsenical vapour, and melts into a grayish-black slag. It contains 40 per cent, of copper, the rest being iron, arsanic, and sulphur. It occurs in primitive and transition rocks. It is found in Cornwall and Saxony. 15. Copper -glance, or vitreous copper. Rliomboidal copper -glance. 1. Compact. Colour blackish lead-gray. Massive, in plates and crystallized. Primitive form, a rhomboid. Secondary forms, a low equiangular six-sided prism, and a double six- sided pyramid. Glistening, metallic. Harder than gypsum. Perfectly sectile. Rather easily frangible. Spec. grav. 5.5 to 5.8. Its consti- tuents are, copper 78.05, iron 2.25, sulphur 18.5, silica Wo. Klaproth. 2. Foliated. Its constituents are, copper 79io, sulphur 19, iron 0.75, quartz 1. - Ull- titaun. It occurs in primitive rocks. It is found also in transition rocks, atFassney-burn in East- Lothian ; in Ayrshire ; at Middleton Tyas in Yorkshire ; in Cornwall, &c. 16. Variegated copper. Colour between copper-red and pinchbeck-brown. Massive, in plates, and crystallized in six sided prisms. Glistening, metallic. Soft. Easily frangible. Spec. grav. 5. It is fusible, but not so easily as copper-glance, into a globule, which acts powerfully on the magnetic needle. Its con- stituents are, copper C9.5, sulphur 19, iron 7.5, oxygen 4. Klaproth. It occurs in gneiss, mica slate, &c. It is found in Corn- wall. VII. GOLD ORES. 1. Hexahcdral, or native gold. a. Gold-yellow native gold. Colour per- feet gold -yellow. Disseminated, in grains, and crystallized; in the octohedron, perfect or truncated ; in the cubo-octohedron ; in the cube, perfect or truncated ; in the double eight- sided pyramid ; in the tetrahedron, and rhom- boidal dodecahedron. Splendent. Fracture, fine hackly. Soft. Difficultly frangible. Malleable. Spec. grav. from 17 to 19, and so low as 12. Fusible into a globule. It is gold with a very minute portion of silver and copper. It occurs in many very different rocks ; and in almost every country. See an exten- sive enumeration of localities, in Jameson's Mineralogy. b. Brass -yclloto native gold, occurs capil- lary ; in octahedrons, and in six-sided tables. Spec. grav. 12.713. Its constituents are, gold 96.9, silver 2, iron 1.1. It is found in the gold mines of Hungary, in Siberia, &c. c. Grayish -yellow native gold. Colour brass-yellow verging on steel-gray. In small flattish grains. Never crystallized. It is said to contain platina. It is rather denser than the last. It occurs along with platina and magnetic iron-ore in South America. d. Argentiferous gold, or electrum. Co- lour pale brass-yellow. In small plates, and imperfect cubes. Its constituents are, 64 gold, 36 silver. It occurs along with massive heavy spar in Siberia. Klaproth says, it is acted on neither by nitric nor nitro-muriatic acid. See TELLURIUM ORES. VIII. IRIDIUM ORE. Colour pale-steel gray. la very small irregular flat grains. Lustre shining and metallic. Fracture foli- ated. Brittle. Harder than platina. Spec, grav. 19.5. By fusion with nitre, it acquires a dull black colour, but recovers its original colour and lustre, by heating with charcoal. It consists of iridium, with a portion of osmium. It occurs in alluvial soil in South America, along with platina. Wollaston. IX. IRON ORES. I. Native, or octahedral iron. a. Terrestrial native iron. Colour steel- gray. Massive, in plates and leaves. Glisten- ing and metallic. Fracture hackly. Opaque. Malleable. Hard. Magnetic. Its constitu- ents are, iron 92.5, lead 6, copper 1.5. Klaproth. It is found with brown iron-stone and quartz in a vein, in the mountain of Oulle, in the vicinity of Grenoble, &c. ORE 633 ORE b. Meteoric native iron. Colour pale-Steel- gray, inclining to silver -white. Generally covered with a thin brownish crust of oxide of iron. It occurs ramose, imperfect globular, and disseminated in meteoric stones. Surface, smooth and glistening. Internally, it is inter- mediate between glimmering and glistening, and the lustre is metallic. Fracture hackly. Fragments blunt-edged. Yields a splendent streak. Intermediate between soft and semi- hard. Malleable. Flexible, but not elastic. Very difficultly frangible. Spec. grav. 7-575. Its constituents are Agram. Arctic. M>xieo. Siberia. Iron, 96-5 07 90-75 90-54 Nickel, 3-5 3 325 9-46 100-0 100 10000 100-00 Klcipr. Brands. Klapr. Children. The American native iron contains 0.10 of nickel; the Siberian 0.17; and the Sene- gambian 0.05 ard 0.06 Howard. It ap- pears to be formed in the atmosphere, by some process hitherto unknown to us. See METEOROLITE, and Jameson's Mineralogij> iii. p. 101. II. Iran ore. a. Octahedral iron ore, of which there are three kinds. 1. Common magnetic iron ore. Colour iron-black. Massive, in granular concretions, and crystallized ; in the octohedron, truncated, bevelled, and cuneiform ; rhomboidal dode- cahedron; rectangular four-sided prism ; cube; tetrahedron ; equiangular six-sided table ; and twin crystal. Splendent and metallic. Cleavage fourfold. Fracture uneven. Streak black. Harder than apatite. Brittle. Spec. grav. 4.8 to 5.2. Highly magnetic, with polarity. Be- fore the blowpipe it becomes brown, and does not melt ; it gives glass of bor;.x a dark green colour. Its constituents are, paroxide of iron 09, protoxide of iron 3\.~Berzelius. It occurs in beds of great magnitude, in primitive rocks, at Unst ; at St. Just in Cornwall ; at Arendal in Norway, &c. It affords excellent bar-iron. 2. Granular magnetic iron ore, or iron- .sand. Colour very dark iron -black. In small grains and octohedral crystals. Glim- mering. Fracture conchoidal. Brittle. Streak black. Spec. grav. 4 6 to 4.8. Magnetical with polarity. Its constituents are, oxide of iron 85-5, oxide of titanium 14, oxide of man- ganese 0-5. Klaproth. It occurs imbedded in basalt, &c. It is found in Fifcshire, in the Isle of Skye, in the river Dee in Aberdeen- shire, &c. 3. Earthy magnetic iron ore. Colour bluish-black. In blunt-edged rolled pieces. Dull. Fracture fine grained uneven. Opaque. Soft. Streak black, shining. Soils. Sectile. It emits a faint clayey smell when breathed on. Sp. gr. 2-2. It occurs in the iron mines of Arendal in Norway. b. llhomboidal iron ore ; of which thciv are three sub-species. 1. Specular Iron ore, iron glance, orfer oligiste of the French. Of this there are two kinds, the common and micaceous. Common specular iron ore. Colour dark steel-gray. Massive, disseminated, and crystallized. Prim, form, a rhomboid, or double three-sided pyra- mid, in which the angles are 87 9', and 92 51'. The secondary figures are, the primitive form variously bevelled, truncated, and acu- minated ; the flat rhomfeoid ; equiangular six- sided table ; low equiangular six- sided prism ; and very acute six-sided pyramid. Lustre, splendent metallic. Cleavage threefold. Frac- ture imperfect conchoidal. Streak cherry-red. Hardness between felspar and quartz. Rather difficultly frangible. Sp. gr. 5-2. Magnetic in a slight degree. Its constituents are, red- dish-brown oxide of iron 94.38, phosphate of lime 2.75, magnesia 0.16, mineral oil 1.25 ? Hisinger. It occurs in beds in primitive mountains. It is found at Cumberhead in Lanarkshire ; at Norberg in Westmannland, in Norway, &c. It affords an excellent mal- leable iron. Micaceous specular iron ore. Colour iron- black. Massive, disseminated, and in small thin six-sided tables, intersecting one another so as to form cells. Splendent, metallic. Cleavage single curved-foliated. Translu- cent in thin plates. Streak cherry -red. As hard as the above. Most easily frangible. Spec. grav. 5.07- It slightly affects the mag- net. It is peroxide of iron. It occurs in beds in mica-slate. It is found at Dunkeld and Benmore in Perthshire ; in several parts of England and Norway, &c. The iron it affords is sometimes cold short, but is well fitted for cast ware. It is characterized by its high de- gree of lustre, openness of its cleavage, and easy frangibility. It affords from 70 to 80 per cent of iron. 2. Red iron ore ; of which there are four kinds, the scaly, ochry, compact, and fibrous. Scaly red iron ore, or red iron froth. Co- lour dark steel-gray to brownish-red. Friable, and consists of semi - metallic shining scaly parts, which are sometimes translucent and soil strongly. It constituents are, iron 66, oxygen 28.5, silica 4.25, alumina 1.25 Henry. But Bucholz found it to be a pure red oxide of iron, mixed with a little quartz sand. It occurs in veins in primitive rocks. It is found at Ulverstone in Lancashire; in Norway, &c. Ochry red iron ore, or red ochre. Colour brownish red. Friable. Dusty dull particles. Soils. Streak, blood-red. Easily frangible. Spec. grav. 2.947- It occurs in veins, with the preceding ore. It melts more easily than any of the other ores of this metal, and affords excellent malleable iron. Compact red iron ore. Colour between dark steel-gray and blood -red. Massive, and in supposititious crystals ; which are an acute double six-sided pyramid from calcareous spar ; and a cube from fluor spar and iron pyrites. ORE ORE lustre metallic. Fracture even. Streak pale blood-red. Easily frangible. Spec, gravity, 4.232. When pure it does not affect the mag- net Its constituents .are, oxide of iron 70.5 ? oxygen 29.5? Bucholz, It occurs in beds and veins in gneiss, &c. It affords good bar and cast-iron. Fibrous red iron ore, or red hematite. Co- lour between brownish-red and dark steel-gray. Massive, imitative, and in supposititious dou- ble six-sided pyramids from calcareous spar. Glistening, semi-metallic. Opaque. Streak blood-red. Brittle. Spec, gravity 4.74. Its constituents are, 90 oxide of iron, silica 2, lime 1, water 3. Daululsson. It occurs with the compact. It affords excellent malleable and cast-iron. Its powder is used for polishing tin, silver, and gold vessels, and for colour- ing iron brown. 3. Red clay iron ore or stone ; of which the varieties are, the ochry, the columnar, the lenticular, and jaspery. The first is used for red crayons, and is called red chalk. It occurs in Hessia, &c. The second consists of 50 oxide of iron, 13 water, 32 silica, and 7 alu- mina Brocchi. It is rare, and is called a pseudo- volcanic product. It affords excellent iron. It consists of oxide of iron 64, alumina 23, silica 7-5, water 5. The jaspery is found in Austria. c. Prismatic iron ore, or brown iron stone, Of this we have four sub-species. 1. Ochry brown iron ore. Yellowish- brown. Massive ; dull. Fracture, earthy ; soils. Soft ; sectile. Its constituents are, peroxide of iron 83, water 12, silica 5. It occurs with the following. $ 2. Compact. Colour passes to clove-brown. Massive, and in supposititious crystals from pyrites. Dull. Brittle. Sp. gr. 3 to 3-7. It contains 84 peroxide of iron, 11 water, and 2 silica. It affords about 50 per cent, of good bar iron. 3. Fibrous. Clove-brown. Imitative ; and in supposititious crystals. Splendent ex- ternally. Glimmering internally. Opaque. Harder than apatite. Brittle. Sp. gr. 3-9. Streak pale yellowish-brown. Its constituents are, 80-25 oxide of iron, 15 water, 3-75 silica, p Vauquelin. The preceding sub-species occur most fre- quently in transition and secondary mountains. They are found in veins in sand-stone, along with heavy spar, at Cumberhead in Lanark- shire, &c. They melt easily, and afford from 40 to 60 per cent, of good bar, but indifferent cast-iron. Good steel may be made from it. 4. Brown clay iron ore ; of which there are five kinds, the common, the pisiform, the reniform, the granular, and umber. The first occurs massive ; has a flat con- choidal fracture ; a brown streak ; and is soft. It contains 69 oxide of iron, 3 manganese, 13 water, 10 silica, and 3 alumina. The second lias a yellowish-brown colour. It occurs in small solid spherical grains, composed of con- centric concretions. Sp. gr. 3-142. It con- sists of 48 oxide of iron, 31 alumina, 15 silica, and C water Vauquelin. It is found in hol- lows in shell limestone, at Galston in Ayr- shire, &c. It yields from 40 to 50 per cent, of iron ; and in Dalmatia it is used as small shot. The third has a yellowish-brown co- lour. Massive, and imitative ; in concentric lamellar concretions, which often include a loose nodule. Glimmering. Sectile. Its con- stituents are, peroxide of iron 76, water 14, silica 5, oxide of manganese 2. It occurs in iron -shot clay in secondary rocks. It is found in East and Mid-Lothian, in Colebrookdale, &c. It yields an excellent iron. The fourth, or granular, occurs massive and in grains. Fracture thick slaty. Streak yellowish-brown. Soft. Brittle. Sp. gr. 3. It occurs in beds between the red limestone of the salt forma- tion, and the lias limestone. It is found in Bavaria, France, &c. It affords about 40 per cent, of good iron. Fifth, Umber. Colour clove-brown. Massive. Dull. Fracture flat conchoidal. Soft. Sectile. Soils strongly. Feels meagre. Adheres strongly to the tongue, and readily falls to pieces in water. Sp. gr. 2-06. It consists of oxide of iron 48, oxide of manganese 20, silica 13, alumina 5, water 14 Klaproth. It occurs in beds in the island of Cyprus. It is used as a pigment. Bog iron ore is arranged as a variety of the above. There are three kinds of it : 1 . Meadow ore, or friable bog iron ore. Colour pale yellowish-brown. Friable. Dull. Fracture, earthy. Soils. Itfeels meagre, but fine. 2. Swamp ore, or indurated bog iron ore. Colour dark yellowish -brown. Corroded and vesicular. Dull. Earthy. Very soft Sectile. Sp. gr. 2-944. 3. Meadow ore, or conchoidal bog iron ore. Blackish-brown. Massive, and tube- rose. Glistening. Fracture, small conchoidal. Streak yellowish -gray. Soft. Sp. gr. 2-6. Its constituents are, oxide of iron 66, oxide of manganese 1-5, phosphoric acid 8, water 23. Klaproth. By Vauquelin's experiments it seems to contain also chrome, magnesia, silica, alumina, and lime ; zinc and lead are likewise occasionally present. It belongs to a recent formation, Werner's ingenious theory of which is given by Professor Jameson, vol. xiii. p. 247. It is found in the Highlands of Scot- land, in Saxony, &c. The second is most easily reduced, and affords the best iron. Pitchy iron ore may also be placed here. Its colour is blackish-brown. Massive. Glis- tening. Fracture flat conchoidal. Translucent on the edges. Hard. Streak yellowish-gray. Brittle. Sp. gr. 3-562. Its constituents are, phosphoric acid 27, manganese 42, oxide of iron 31. Vauquelin. It occurs near Limoges in France. Iron sinter. Colour brown. Massive and imitative. Glistening. Fracture flat conchoidal. Translucent. Soft. Brittle. Sp. gr. 2-4. Its constituents are, water 25, oxide of iron 67, ORE 635 ORE sulphuric acid 8. Klaproth. It occurs in the galleries of old mines in Saxony and Silesia. III. Iron pyrites. 1. Hcxahedral or common iron pyrites. Colour perfect bronze-yellow. Massive, imi- tative, and crystallized; in cubes, variously bevelled. Lustre from specular-splendent, to glistening and metallic. Cleavage hexahedral. Fracture uneven. Harder than felspar, but softer than quartz. Brittle. When rubbed it emits a strong sulphureous smell. Sp. gr. 4-7 to 5. It burns with a bluish flame and sulphureous odour before the blowpipe. It afterwards changes into a brownish-coloured globule, which is attractible by the magnet. Its constituents are, sulphur 62-5, iron 47 5. Hutchett. Siiver and gold are occasionally present. It occurs in beds in various moun- tains. It is worked for sulphur or copperas. 2. Prismatic iron pyrites. a. Radiated pyrites. Colour pale bronze- yellow. Most usually imitative, or crystal. lized. Primitive form, is an oblique four, sided prism, in which the obtuse angle is 106 3(i'. Secondary forms are, the above variously bevelled ; and the wedge-shaped double four- sided pyramid. Harder than felspar. Sp. gr. 4-7 to 5-0. Its constituents are, sulphur 53-6, iron 46-4. Hatchett. It is much rarer than the preceding. It is found in Cornwall, Isle of Sheppy, &c. b. Hepatic or liver pyrites. Colour pale brass-yellow. Massive and imitative. Glim- mering and metallic. Fracture uneven. Sp. gr. 4-834. It occurs in veins in primitive rocks. It is found in Derbyshire, &c. c. Cellular pyrites. Colour bronze-yellow. Cellular. Surface of the cells drusy. Fracture flat conchoidal. It occurs in veins at Johann- georgenstadt in Saxony. d. Spear pyrites. Colour between bronze- yellow and steel-gray. Crystallized in twin or triple crystals. Fracture uneven. It occurs in veins in primitive rocks, associated with brown coal. e. Cockscomb pyrites. Colour as above. Crystallized in double four-sided pyramids. Glistening and metallic. It occurs in Derby- shire. 3. Ilhomboidal iron pyrites or magnetic pyrites. a. Foliated magnetic. Colour between bronze-yellow and copper-red. Massive, and sometimes crystallized, in a regular six-sided prism, truncated ; and in a six-sided pyramid. Splendent and metallic. Sp. gr. 4-4 to 4-6. It occurs in Saxony. b. Compact magnetic. Same colour. Mas- sive. It affects the magnetic needle. Its constituents are, sulphur 30.5, iron 63-5 Hatchett. It is found in Galloway and Caer- narvonshire. IV. Native salt* of iron. a. The Prismatic chromc~orc. Colour be- tween steel-gray and iron-black. Massive, and in oblique four -sided prisms, acuminated with four planes. Lustre imperfect metallic. Fracture small grained uneven. Opaque. Hardness, between apatite and felspar. Streak dark brown. Sp. gr. 4-4 to 4-5. Some va- rieties are magnetic, others not. It is infusible before the blowpipe. With borax, it forms a beautiful green-coloured mass. The consti- tuents of the French are, oxide of iron 34-7, oxide of chrome 43, alumina 20-3, silica 2 Hauy. The Siberian contains 34 oxide of iron, 53 oxide of chrome, 11 alumina, 1 silica, and 1 manganese. Laugier. It occurs in primitive serpentine. It is found in the islands of Unst and Fetlar, in Scotland ; and also at Portsoy in BanfFshire. In considerable quan- tity in serpentine on the Bare-hills near Balti- more. b. Sparry iron, or carbonate of iron. Co- lour pale yellowish -gray. Massive, dissemi- nated and crystallized. The primitive form is a rhomboid of 107. The following are some of the secondary forms : the primitive rhom- boid, perfect or truncated ; a still flatter rhom- boid ; the spherical lenticular form..; the sad- dle-shaped lens ; the equiangular six-sided prism. Glistening and pearly. Cleavage threefold. Fracture foliated. Translucent on the edges, or opaque. Streak white or yellow- ish-brown. Harder than calcareous spar. Sp. gr. 3-6 to 3-9. It blackens and becomes mag- netic before the blowpipe. It effervesces with muriatic acid. Its constituents are, oxide of iron 57-5, carbonic acid 36, oxide of manga- nese 3-5, lime 1-25. Klaproth. It occurs in veins in granite, and in limestone. In small quantities hi Britain. In great quantity at Schmalkalden in Hessia. It affords an iron well suited for making steel. c. Rhomboidal vitriol, or green -vitriol. Co- lour emerald-green. Primitive form of the cry- stals is a rhomboid, with edges of 81 23' and 98 37'; and plane angles of 100 10' and 79 5(K. Vitreous or pearly lustre. Cleavage threefold. Fracture flat conchoidal. Semi- transparent. Refracts double. As hard as gypsum. Sp. gr. 1-9 to 2-0. Taste sweetish, styptic, and metallic. Before the blowpipe, on charcoal, it becomes magnetic. Its con- stituents are, oxide of iron 25-7, sulphuric acid 28-9, water 45-4. Berzclius. It results from the decomposition of iron pyrites. d. Arseniate of iron. See CUBE ORE. e. Blue iron, or phosphate of iron. Prismatic blue iron. 1. Foliated blue iron. Colour dark in- digo-blue. Primitive form an oblique four- sided prism. The secondary forms are, a broad rectangular four-sided prism, truncated ; and an eight-sided prism. Shining. Cleavage straight, single. Translucent. As hard as gypsum. Streak paler blue. Sectile, and easily frangible. Flexible in thin pieces. Sp. gr. 2-8 to 3-0. Its constituents are, oxide of ORE 636 ORE iron 41-25, phosphoric acid 19-25, water 31-25, iron-shot silica 1-25, alumina 5. Fourcroy and Laugier. It occurs in St. Agnes's in Cornwall. 2. Fibrous Hue iron. Colour indigo- blue. Massive, and in delicate fibrous con- cretions. Glimmering and silky. Opaque. Soft. It occurs in syenite at Stavern in Norway. 3. Earthy blue iron. Colour as above. Friable, and in dusty particles. Soils slightly. Rather light. Before the blowpipe it loses its blue colour, becomes reddish-brown, and lastly melts into a black-coloured slag, attractible by the magnet. Its constituents are, oxide of iron 47* phosphoric acid 32, water 20. Klaproth. It occurs in nests in clay-beds. In several of the Shetland islands, and in river mud at Toxteth, near Liverpool. 4. T it ng state of iron. See ORES of TUNG- STEN. 5. Blue ironstone. Colour indigo-blue. Massive, and with impressions of crystals of brown iron ore. Glimmering, or dull. Frac- ture coarse grained uneven. Opaque. Semi- hard. Rather brittle. Sp. gr. 3-2. Klaproth. It loses its colour by heat ; and with borax forms a clear bead. Its constituents are, oxide of iron 40.5, silica 50, lime 1-5, natron 6, water 3. It occurs on the banks of the Orange River in South Africa. X. LEAD ORES. 1. Galena, or lead-glance. Hexahedral galena. 1. Common. Colour fresh lead-gray. Massive, imitative, and crystallized in cubes, octohedrons, rectangular four-sided prisms, broad unequiangular six-sided prisms, six- sided tables, and three-sided tables. Specular splendent, to glimmering. Lustre metallic. Cleavage hexahedral. Fragments cubical. Harder than gypsum. Sectile and frangible. Sp. gr. 7 to 7 - 6. Before the blowpipe it flies in pieces, then melts, emitting a sulphureous odour, while a globule of lead remains. Its constituents are, lead 83, sulphur 16-41, silver 0-08. Westrumb. It occurs in beds, &c. in various mountain rocks ; at Leadhills in La- narkshire, &c. Nearly all the lead of com- merce is obtained from galena. The ore is roasted and then reduced with turf. 2. Compact galena. Colour somewhat darker than the preceding. Massive, shining, metallic. Fracture flat conchoidal. Streak more brilliant. It consists of sulphuret of lead, sulphuret of antimony, and a small por- tion of silver. It is found at Leadhills in Lanarkshire, in Dsrbysbire, &c. J3. Friable galena. Colour dark fresh -gray. Massive and in thick flakes. Sec- tile. It is found only around Freyberg. Blue lead. Colour between very dark in- digo-blue and dark lead-gray. Massive, and crystallized in regular six-sided prisms. Feebly glimmering. Soft. Sectile. Sp. gr. 5461. It is conjectured to be sulphuret of lead, intermixed with phosphate of lead. It occurs in veins. It has been found in Saxony and France. Cobaltic galena. Colour fresh lead-gray. Minutely disseminated in exceedingly small crystals, aggregated in a moss-like form. Shining and metallic. Scaly foliated. Opaque. Soft. Soils feebly. It communicates a smalt-blue colour to glass of borax. It occurs near Clausthal in the Hartz. 2. Lead spar. 1. Triprismutic lead spar, or sulphate of lead. Colours yellowish and grayish-white. Massive and crystallized. In the primitive form the vertical prism is 120. The principal crystallizations are, an oblique four-sided prism, variously bevelled or truncated ; and a broad rectangular four-sided pyramid. Lustre shining, adamantine. Fracture conchoidal. Translucent. As hard as calcareous spar. Streak white. Brittle. Sp. gr. 6.3. It de- crepitates before the blow-pipe, then melts, and is soon reduced to the metallic state. Its constituents are, oxide of lead 7^-5, sulphuric acid 25.75, water "2.25.KlavrotA. It occurs in veins along with galena at Wanlockhead in Dumfries-shire, Leadhills, Pary's mine, and Penzance. 2. Pyramidal lead spar, or yellow lead spar. Colour wax-yellow. Massive, cellular, and crystallized. Its primitive form is a pyramid, in which the angles are 99 40' and 131 45'. Its secondary forms are, the pyra- mid variously truncated on the angles and summits, and a regular eight-sided table. Lustre resinous. Cleavage fourfold. Fracture uneven. Translucent. As hard as calcareous spar. Brittle. Sp. gr. 6.5 to 6.8. Mohs. (5.706, Hatchett). Its constituents are, oxide of lead 58.4, molvbdic acid 38, oxide of iron 2.08, silica 0.28.' Hatchett. It occurs at Bleiberg in Carintbia. 3. Prismatic lead spar, or red lead spar. Colour hyacinth-red. Crystallized, in long slightly oblique four-sided prisms, variously bevelled, acuminated, or truncated. Splendent, adamantine. Fracture uneven. Translucent. Streak between lemon-yellow and orange- yellow. Harder than gypsum. Sectile. Easily frangible. Sp. gr. 6.0 to 6.1. Before the blowpipe it crackles and melts into a gray slag. It does not effervesce with acids. Its consti- tuents are, oxide of L>ad 63.96, chromic acid 36.4 Vauqitelin. It occurs in veins in gneiss in the gold mines of Beresofsk in Siberia. 4. Rhomboidal lead spar. a. Green lead spar. Colour grass-green. Imitative or crystallized. The primitive form is a dirhomboid, or a flat equiangular double six-sided pyramid. The secondary forms are, the equiangular six-sided prism, variously truncated and acuminated. Splendent. Frac- ture uneven. Translucent. Sometimes as ORE 637 ORE hard as fluor. Brittle. Sp. gr. 6.9 to 7-2. It dissolves in acids without effervescence. Its constituents are, oxide of lead 80, phos- phoric acid 18, muriatic acid 1.62, oxide of iron, a trace. Klaproth. It occurs along with galena at Leadhills, and Wanlockhead ; at Alston in Cumberland, &c. b. Brown lead spar. Colour clove-brown. Massive and crystallized; in an equiangular six-sided prism ; and an acute double three- sided pyramid. Glistening, resinous. Feebly translucent. Streak grayish- white. Brittle. Sp. gr. 6-91. It melts before the blowpipe, and, during cooling, shoots into acicular crystals. It dissolves without effervescence in nitric acid. Its constituents are, oxide of lead 78.58, phosphoric acid 19-73, muriatic acid 1.65. It occurs in veins that traverse gneiss. It is found at Miess in Bohemia. 5. Diprismatic lead spar. a. White lead spar. Carbonate of lead. Colour white. Massive and crystallized; in a very oblique four-sided prism ; an unequi- angular six-sided prism; acute double six-sided pyramid ; oblique double four-sided pyramid ; long acicular crystals ; and in twin and triple crystals. Lustre adamantine. Fracture small conchoidal. Translucent.. Refracts double in a high degree. Harder than calcareous spar. Brittle. Sp. gr. 6.2 to 6.6. It dis- solves with effervescence in muriatic and nitric acids. It yields a metallic globule with the blowpipe. Its constituents are, oxide of lead 82, carbonic acid 16, water 2. Klaproth. It occurs in veins at Leadhills in Lanarkshire. b. Black lead spar. Colour grayish- black. Massive, cellular, and seldom crystallized, in very small six-sided prisms. Splendent, me- tallo-adamantine. Fracture uneven. Streak whitish-gray. Its constituents are, oxide of lead 79, carbonic acid 18, carbon 2 Lam- padius. It occurs in the upper part of veins, at Leadhills, &c. c. Earthy lead spar. Colour yellowish- gray. Massive. Glimmering. Opaque. Streak brown. Very soft. Sp. gr. 5.579. Its constituents are, oxide of lead 66, car- bonic acid 12, water 2.25, silica 10.5, alumina 4.75, iron and oxide of manganese 2.25. John. It is found at Wanlockhead. Corneous lead ore, or muriate of lead. Colour grayish-white. Crystallized, in an oblique four-sided prism, variously truncated, bevelled, and acuminated. Splendent and adamantine. Cleavage threefold. Fracture conchoidal. Transparent. Soft. Sectile, and easily frangible. Sp. gr. 6.065. It melts into an orange-coloured globule. Its con- stituents are, oxide of lead 85.5, muriatic acid 8.5, carbonic acid 6. Klaproth. It is found in Cromford-level near Matlock in Derbyshire. Arseniate of lead. 1. Reni/brm. Colour reddish-brown. Shining. Fracture conchoidal. Opaque. Soft and brittle. Sp. gr. 3.933- It gives out arsenical vapours with the blowpipe. 1 1 colours glass of borax lemon-yellow. Its constituents are, oxide of lead 35, arsenic acid 25, water 10, oxide of iron 14, silver 1.15, silica 7, alumina 2. It is found in Siberia. 2. Filamentous. Colours green or yellow. In acicular six-sided prisms, or in silky fibres. Slightly flexible and easily frangible. Sp. gr. 5.0 to 6.4. Its consti- tuents are, oxide of lead 69.76, arsenic acid 26.4, muriatic acid 1.58 Gregor. It occurs in Cornwall. 3. Earthy arseniate. Colour yellow. In crusts. Friable. It occurs at St. Prix in France. Native minium. Colour scarlet-red. Mas- sive, amorphous, and pulverulent. It is found in Grassington-moor, Craven. Mr. Smithson thinks this mineral is produced by the decay of galena or lead-glance. XI. MANGANESE ORES. 1. Prismatic manganese ore. 1. Gray manganese ore. a. Fibrous gray manganese ore. Colour dark steel-gray. Massive, imitative, and in very delicate acicular crystals, and in thin and long rectangular four-sided tables. Shining and splendent. Soils strongly. Soft. Brittle. It occurs in the Westerwald. b. Radiated. Colour dark steel-gray. Massive, imitative, ar.d crystallized. The primitive form is an oblique four-sided prism, in which the largest angle is about 1<<0. Secondary forms are, the primitive bevelled, or acuminated, or spicular crystals. Cleavage prismatic. Streak dull black. Soils. Soft. Brittle. Sp. gr. 4.4 to 4.8. Shining and metallic. Its constituents are, black oxide of manganese 90.5, oxygen 2.25, water 7. Klaproth. It occurs in the vicinity of Aber- deen, in Cornwall, Devonshire, &.c. c. Foliated. Colour between steel-gray and iron-black. Massive and crystallized in short oblique four-sided prisms. Shining, metallic. Cleavage prismatic. Fracture uneven. Other characters, as above. Sp. gr. 3-742. It is found in Devonshire. d. Compact. Fracture even, or flat con- choidal. Sp. gr. 4 to 4.4. Other characters as preceding. Its constituents are, yellow oxide of manganese 50? oxygen 33, barytes 14, silica 1 to 6. Analysis doubtful. It occurs at Upton Pyne in Devonshire. c. Earthy. Friable. It consists of semi- metallic feebly glimmering fine scaly particles, which soil strongly. It occurs in the mine Johannis in the Erzegebirge. It tinges borax purple; ar.d effervesces with muriatic acid, giving out chlorine. These five kinds occur in granite, gneiss, &c. either in veins or in large cotemporaneous masses. 2. Black manganese ore. a. Compact. Colour between bluish-black and steel-gray. Massive, imitative, and in ORE 638 ORE curved lamellar concretions. Glimmering and imperfect metallic lustre. Fracture conchoidal. Streak shining, with colour unchanged. Semi- hard. Brittle. Sp. gr. 4.75. b. Fibrous, Massive, imitative, and in delicate scopiform concretions. Fragments cuneiform and splintery. Its other characters as above. It yields a violet-blue glass with borax. It occurs in veins in the Erzegebirge. It yields a good iron ; but acts very power- fully on the sides of the furnace. It is called black hematite. c. Foliated. Colour brownish-black. Crys- tallized sometimes in acute double four-sided pyramids. Shining. Cleavage single, and curved foliated. Streak dark reddish-brown. Brittle. It is supposed to consist of iron and manganese. 3. Scaly brown manganese ore. Colour between steel-gray and clove-brown. In crusts. Massive and imitative. Friable. Composed of shining scaly particles. Soils strongly. Feels greasy. It gives to glass of borax an olive-green colour. It occurs in drusy cavities in brown hematite. It is found near Sand- lodge in Mainland, one of the Shetlands. 4. Manganese blende. Prismatic. Colour iron -black. Massive, in distinct concretions, and sometimes crys- tallized. Primitive form, an oblique four- sided prism, which becomes variously modified by truncations on the lateral edges. Lustre splendent, and semi-metallic. Streak greenish. Harder than calcareous spar. Easily frangi- ble. Before the blowpipe it gives out sulphur, and tinges borax violet-blue. Its constituents are, oxide of manganese 82, sulphur ll.fi, carbonic acid 5. Klaproth. Oxide of man- ganese 85, sulphur 15. Vauquelln. It is found in Cornwall. 5. Phosphate of manganese. Colour brownish-black. Massive and disseminated. Glistening. Fracture flat conchoidal. Semi- transparent, in splinters. Scratches glass. Streak yellowish-gray. Brittle. Sp. gr. 3.5 to 3.7. It is fusible into a black enamel. Its constituents are, oxide of manganese 42, oxide of iron 31, phosphoric acid 27- It occurs in a coarse granular granite at Li- moges in France. 6. Rhomboidal red manganese. a. Foliated. Colour bright rose-red. Mas- sive, imitative, and crystallized in rhomboids. Shining, pearly. Cleavage rhomboidal. Trans- lucent on the edges. Hardness between fluor and calcareous spar. Brittle. Sp. gr. 3.3 to 3.6. Before the blowpipe it first becomes dark brown, and then melts into a reddish- brown bead. Its constituents are, oxide of manganese 52.6, silica 39.6, oxide of iron 4.6, lime 1.5, volatile ingredients 2.75. Berzelius. It occurs in beds of specular iron ore in gneiss hills in Sweden and Siberia. The specimens of the latter are cut into ornamental stones. b. Fibrous. Colours, rose-red and flesh red. Massive and indistinct prismatic fibrous concretions. Glistening and pearly. Frag- ments splintery. Feebly translucent. It occurs in Transylvania and Hungary. c. Compact. Colour pale rose-red. Mas- sive or reniform. Glimmering. Sp. gr. 3.3 to 3.9. Its constituents are, oxide of man- ganese 61, silica 30, oxide of iron 5, alumina 2. Lampad. It occurs at Kapnik in Tran- sylvania. Pitchy Iron ore may be regarded as a phos- phate of manganese. XII. MERCURY ORES. 1. Native mercury. a. Fluid mercury. See MERCURY. It occurs principally in rocks of the coal forma- tion, associated with cinnabar, corneous mer- cury, &c. Small veins of it are rarely met with in primitive rocks, accompanied with native silver, &c. It is found at Idria in the Friaul ; Niderslana in Upper Hungary ; in the Palatinate ; Deux-Ponts, &c. b, Dodecahedral mercury , or native amal- gam. 1. Fluid or semi-fliiid amalgam. Colour tin-white. In roundish portions ; and crys- tallized in a rhomboidal dodecahedron, rarely perfect. Splendent. When cut it emits a creaking sound. As hard as talc. Sp. gr. 10-5. Its constituents are, mercury 74, silver 25. It is found at Deux-Ponts. 2. Solid amalgam. Colour silver-white. Massive and disseminated. Fracture flat conchoidal. As hard as gypsum. Brittle. Creaks strongly when cut. Sp. gr. 10.5. The mercury flies off before the blowpipe. Its constituents are, mercury 74, silver 25. Hcyer. Mercury 64, silver 36. Klap- roth. It is found in Hungary, the Deux- Fonts, &c. 2. Cinnabar, or prismato-rhomboidal ruby- blende. a. Dark red cinnabar. Colour cochineal- red. Massive, disseminated, imitative, and crystallized. Primitive form a rhomboid. Secondary forms ; a regular six-sided prism, an acute rhomboid, and a six-sided table. Splendent, adamantine. Translucent. Streak scarlet-red, shining. Harder than gypsum. Sectile and easily frangible. Sp. gr. 6-7 to 8-2. It melts, and is volatilized with a blue flame and sulphureous odour. Its consti- tuents are, mercury 84-5, sulphur 14-75., Klaproth. b. Bright red cinnabar. Colour bright scarlet-red. Massive, and in delicate fibrous concretions. Glimmering and pearly. Frac- ture earthy. Opaque. Streak shining. Soils. Friable. It occurs in rocks of clay-slate, talc- slate, and chlorite slate ; in veins at Horzowitz in Bohemia ; at Idria, &c. c. Hepatic cinnabar. 1. Compact. Colour between cochineal- red and dark lead-gray. Massive. Glim- mering and semi-metallic. Streak shining. ORE 639 ORE Opaque. Soft. Sectile. Sp. gr. 7-2. Its constituents arc, mercury 81-8, sulphur 13-75, carbon 2-3, silica 0-65, alumina 0.55, oxide of iron 0-2, copper 0-02, water 0-73. 2. Slaty mercurial hepatic ore. Colour as above, but sometimes approaching to black. Massive, and in roundish concretions. Lustre shining, semi-metallic. Fracture curved slaty. Most easily frangible. Streak cochineal-red, inclining to brown. Rather lighter than the compact. It occurs in considerable masses in slate-clay and bituminous shale. It is most abundant in Idria. 3. Corneous mercury, or horn quicksilver. Pyramidal corneous mercury. Colour ash- gray. Vesicular, with interior crystallizations, which are, a rectangular four-sided prism, variously acuminated, and a double four- sided pyramid. Crystals very minute. Shining, adamantine. Cleavage single. Faintly trans- lucent. Soft. Sectile and easily frangible. It is totally volatilized before the blowpipe, with a garlic smell. It is soluble in water, and the solution mixed with lime-water gives an orange-coloured precipitate. Its constituents are, oxide of mercury 76, muriatic acid 16-4, sulphuric acid 7-6. Klaproth.It occurs in Bohemia, &c. XIII. MOLYBDENA ORES. Rhomboidal molybdena. Colour fresh lead- gray. Massive, in plates, and sometimes crystallized. Primitive form is a rhomboid. Secondary figures are, a regular six-sided table, and a very short six-sided prism, flatly acuminated on both extremities. Splendent, metallic. Cleavage single. Opaque. Streak on paper bluish-gray ; on porcelain greenish- grey. Soils slightly. Harder than talc. Easily frangible. Splits easily. In thin leaves flexible, but not elastic. Sectile, approaching to malleable. Feels greasy. Sp. gr. 4-4 to 4-6. It emits a sulphureous odour before the blow- pipe. It is soluble, with violent effervescence, in carbonate of soda. Its constituents are, molybdena 60, sulphur 40 Buchoh. It occurs disseminated in granite, gneiss, &c. It is found in Glenelg in Inverness-shire, at Peterhead, at Corybuy at the head of Loch Creran, in Cornwall, &c. Molybdena ochre. Colour sulphur-yellow. Disseminated and incrusting molybdena. Fria- ble ; dull. In Corybuy and Norway. For Molyldatc of lead, see LEAD ORES. XIV. NICKEL ORES. 1. Native nickel Colour brass-yellow. In delicate capillary crystals. Shining and me- tallic. Crystals rigid. Brittle. It consists, according to Klaproth, of nickel, with a small quantity of cobalt and arsenic. It occurs in veins in gneiss in Saxony. 2. Nickel pyrites, or copper-nickel. Prismatic nickel pyrites. Colour copper- red, becoming black. Massive, disseminated, imitative, and crystallized, in oblique four- sided prisms. Shining, metallic. Harder than apatite. Rather difficultly frangible. Sp', gr. 7-5 to 7-7. It emits an arsenical vapour before the blowpipe, and then fuses into a dark- scoria, mixed with metallic grains. It yields a dark green solution with nitro-muriatic acid. Its constituents are, nickel and arsenic, with accidental admixtures of cobalt, iron, and sulphur. It generally occurs in primitive rocks. It is found in small quantities at Leadhills and Wanlockhead, and in the coal field of Linlithgowshire. Black nickel. Colour dark grayish-black. Massive, and in crusts. Dull. Earthy frac- ture. Soft. Streak shining. Soils slightly. It forms an apple-green coloured solution with nitric acid, which lets fall a white pre- cipitate with arsenic acid. It occurs in veins that traverse bituminous marie- slate at Rie- gelsdorf. Nickel ochre. Colour apple-green. In an efflorescence. Dull. Fracture splintery. Soft; Feels meagre. It gives to glass of borax a hyacinth-red colour. It occurs at Leadhills, at Alva in Stirlingshire, and in Saxony. It consists of oxide of nickel 67, oxide of iron 23.2, water 1.5, loss 8-3. Lampadiits. XV. PALLADIUM ORE. Native palladium. Colour pale steel-gray, passing into silver- white. It occurs in small grains. Lustre metallic. Fracture diverging fibrous. Opaque. Sp. gr. 11-8 to 12-148. It is infusible; but on the addition of sulphur it melts. It forms a deep red solution with nitric acid. It consists of palladium, alloyed with a minute portion of platina and iridium. It is found in grains along with grains of native platina, in the alluvial gold districts in Brazil. Wollaston. XVI. PLATINA ORE. Colour very light steel-gray. In flat small grains. Shining and metallic. Nearly as hard as iron. Malleable. Sp. gr. 17-7 It is found in the gray silver ore of Guadalcanal in Spain, in Choco, in New Granada, and in the province of Bar- bacoas. It is peculiar to an alluvial tract of 600 leagues, where it is associated with grains of native gold, zircon, spinel, quartz, and magnetic ironstone. It is not true that this metal occurs near Carthagena, or Santa Fe, or in the islands of Porto Rico and Barbadoes, or in Peru, although these different localities are mentioned by authors. The gray copper ore of Guadalcanal in Spain contains from 1 to 10 per cent, of platina. XVII. SILVER ORES. 1. Hcxahedral, or native silver. a. Common native silver. Colour pure silver- white. Disseminated, in plates or membranes, imitative, and crystallized ; in a cube ; octo- hedron ; tetrahedron ; rhomboidal dodecahe- dron ; leucite form ; and six-sided table. Crystals microscopic. Shining and metallic. Fracture fine hackly. Streak splendent. Harder than gold, tin, lead; but softer than iron, platina, and copper. Perfectly malleable. ORE 640 ORE Flexible, and difficultly frangible. Sp. gr. 10 to 10-4. Its constituents are, metallic silver 99, metallic antimony 1, with a trace of copper and arsenic John. It occurs principally in veins in primitive mountains. In granite in the Erzegebirge. In gneiss and mica-slate in Saxony, Bohemia, and Norway. In clay-slate in Ireland. In clay porphyry at Alva, in the Ochil Hills, Stirlingshire. For a copious list of localities, see Jameson'' s Mineralogy. b. Auriferous native silver. Colour between brass-yellow and silver-white. Disseminated in membranes, and crystallized in cubes. Its sp. gr. is greater than that of the preceding. Its constituents are, silver 72, gold 28. Fordyce. It occurs in veins in primitive rocks at Kongsberg in Norway. 2. Silver-glance, or vitreous silver. 1. Hexaliedral. a. Compact. Colour dark blackish lead- gray. Massive, imitative, and crystallized ; in a cube, octohedron, rhomboiclal dodecahedron, and double eight-sided pyramid. Glistening, metallic. Cleavage rhomboidal. Harder than gypsum. Completely malleable. Flexible, but not elastic. Difficultly frangible. Sp. gr. 5-7 to 6-1. Before the blowpipe it loses its sulphur, and a bead of pure silver remains. Its constituents are, silver 85, sulphur 15. Klaproth. It is one of the most frequent of the ores of silver. It occurs in mica-slate, clay-slate, grey wacke, and seldomer in granite. It is found in Cornwall. 1. Earthy. Colour bluish-black. In crusts. Friable or solid. Dull. Feebly translucent. Streak shining metallic. Soils a little. Easily frangible. Sectile. It is easily fused by the blowpipe. It is a sulphuret of silver. 2. Rhomboidal silver glance. Colour between iron-black and blackish lead-gray. Crystallized. Primitive form, a rhomboid. Secondary figures ; an equiangular six-sided prism, an equiangular six-sided table, and a double six-sided pyramid. The tabular crys- tals often intersect each other, forming cells. Highly splendent, and metallic. Soft. Sectile. Easily frangible. Sp. gr. 5-7 to 6-1. It melts with difficulty. Its constituents are, silver 66-5, sulphur 12, antimony 10, iron 5, copper and arsenic 05, earthy substances 1-0. It occurs in gneiss, &c. It is found in the district of Freyberg. 2. White silver. Colour very light lead- gray. Massive, disseminated, and always associated with lead-glance. Glistening and metallic. Fracture even. Soft. Sectile. Easily frangible. Sp. gr. 5-3 to 5-6. Before the blowpipe it melts and partly evaporates, leaving a bead of impure silver, surrounded by a yellow powder. Its constituents are, lead 41, silver 9-25, antimony 21-5, iron 1-75, sulphur 22, alumina 1, silica 0-75. Klaproth. It occurs in gneiss. It is found near Freyberg. 3. Gray silver, or carbonate of silver. Colour ash-gray. Massive and disseminated. Glistening. Fracture uneven. Soft. Streak more shining. Brittle. Heavy. Easily reduced before the blowpipe. Its constituents are, silver 72-5, carbonic acid 12, oxide of antimony, and a trace of copper 15-5. Sclb. It occurs in veins that traverse granite in the Black Forest. 4. Antimonial silver, or dcdecalicdral an- timony. Colour between silver-white and tin-white. Massive, disseminated, in distinct concretions, and crystallized ; in a rectangular four-sided prism, in an equiangular six-sided prism, and a double six-sided pyramid, trun- cated on the apices. Surface of the prisms longitudinally streaked. Splendent, metallic. Cleavage octohedral. Hardness, between calc and fiuor spar. Sp. gr. 9.4 to 10. The an- timony is volatilized before the blowpipe, and silver remains on the charcoal. Its consti- tuents are, silver 78, antimony 22. Vaua_uc- lin. It occurs in veins in granite and grey- wacke. In the first, at Altwoltach in Suabia ; hi clay-slate in the Hartz. 5. Arsenical silver. Colour on the fresh surface tin-white, which tarnishes grayish- black. Massive, and reniform. Fracture small-grained uneven. Harder than anti- moniai silver. Streak shining. Sectile, and easily frangible. Sp. gr. 9.44. Before the blowpipe the antimony and arsenic are vola- tilized wiih a garlic smell, while a globule of silver remains, which is more or less pure. Its constituents are, arsenic 35, iron 44.25, silver 12.75, antimony 4. It generally occurs along with native arsenic. It is found in the Hartz. 6. Bismuthic silver. Colour pale lead- gray. Disseminated, and rarely crystallized in capillary crystals. Glistening and metallic. Soft Sectile. Easily frangible. Its consti- tuents are, bismuth 27, lead 33, silver 15, iron 4.3, copper 0.9, sulphur 16.3. Klap- roth. It has been found only in the Friedrich- Christian Mine in the Black Forest, in veins, in gneiss. 7- Ruby-blende. 1. Rliomboidal ruby -blende. a. Dark red silver. Colour between cc- chineal-red, and dark lead-gray. Massive, in membranes, and crystallized. Prim, form, a rhomboid of 10i> 28'. Secondary forms, an equiangular six-sided prism, variously trun- cated and acuminated ; and an equiangular double six-sided pyramid. Splendent and adamantine. Cleavage rhomboidal. Semi- transparent. Streak cochineal-red. Harder than gypsum. Sectile. Easily frangible. Sp. gr. 5.2 to 5.7. Before the blowpipe, it first decrepitates, then melts with a slight effervescence, leaving a globule of silver. Its constituents are, silver GO, antimony 20.3, sulphur 14.7, oxygen 5. Klaproth. It oc- curs in veins in gneiss, &c. It is found in the silver mines of Kongsberg, and in those of the Hartz. 2. Light red silver. Colour cochineal- ORE 641 ORE red. Streak aurora-red, passing into cochi- neal-red. Sp. gr. 5-5 to 5.9. In other re- spects, as preceding. Its constituents are, silver 54.27, antimony 16.3, sulphur 17-75, oxygen 11.85. Vauquclln. It occurs at An- dreasberg in the Hartz. XVIII. TANTALUM ORES. 1. Prismatic tantalum ore. Columbite of Hatchctt. Colours grayish and brownish- black. Massive, disseminated, and crystal- lized in oblique four-sided prisms. Semi- metallic adamantine lustre. Fracture coarse- grained uneven. Opaque. As hard as fel- spar. Difficultly frangible. Sp. gr. 6.0 to C.3. It does not fuse with glass of borax. Its constituents are, irollaston. oxide of tantalum, 85 80 oxide of iron, 10 15 oxide of manganese, 4 5 Finland. N. American or Columbite. It occurs in a coarse red granite in Finland, and in Massachusset's Bay, in North Ame- rica. 2. Yttrotantalite. Colours iron-black and yellowish brown. Embedded in angular pieces, and crystallized in oblique four-sided and in six-sided prisms. Resinous, metallic lustre. Fracture conchoidal. Opaque. Scratches glass. Streak gray-coloured. Easily fran- gible. Sp. gr. 5.4 to 5-88. It decrepitates, but does not fuse, with the blowpipe. Its constituents are, oxide of tantalum 57, yttria 20.25, lime 6.25, oxide of iron 3.5, oxide of uranium 0.5, tungstic acid 8.25. It occurs along with gadolinite in a bed of flesh-red felspar in gneiss at Ytterby in Sweden. XIX. TELLURIUM ORES. 1. Hexahedral or native tellurium. Colour tin-white. Massive, disseminated, and in rectangular four-sided prisms, acuminated with four planes. Shining, metallic. Cleav- age hexahedral. As hard as gypsum. Ra- ther brittle. Sp. gr. 6.1 to 6.2. It melts as easily as lead, emits a thick white smoke, and burns with a light green colour, and a pun- gent acrid odour, like that of horse-radish. Its constituents are, tellurium 92.55, iron 7-2, gold 0.25. It occurs in veins in graywacke, at Faceby in Transylvania, and in Norway. 2. Prismatic black tellurium. Colour be- tween blackish lead-gray and iron-black. M as- sive, in flakes, and crystallized. Primitive figure, an oblique four-sided prism. Second- ary forms are, an oblique four-sided table, a six-sided table, an eight-sided table, and an acute double four -sided pyramid. Splendent and metallic. Fragments tabular. Harder than talc. Sectile. Soils slightly. The thin leaves and tables are flexible. Sp. gr. 7.0 to 7.2. It melts very easily before the blowpipe. Its constituents are, tellurium 32.2, lead 54, gold 9, sulphur 3, copper 1.3, silver 0.5. Klaproth. It is worked for the gold it con- tains. It is found at Naygag in Transyl- vania. 3. Prismatic gold glance. 1. Graphic fold glance, or tellurium. Colour steel-gray. Massive, in leaves and crystallized. Primitive form, an oblique four- sided prism. Splendent, metallic. Cleavage prismatic. Fracture fine-grained uneven. As hard as gypsum. Brittle. Soils slightly. Sp. gr. 5.7 to 5.8. Before the blowpipe it burns with a green flame, and is volatilized. Its constituents are, tellurium 60, gold 30, silver 10. It occurs in porphyry hi Transyl- vania. 2. Yellow gold glance, or yellow tellu- rium. Colour silver- white, inclining to brass- yellow. Disseminated and crystallized, in four-sided acicular prisms, which are rare. Splendent, metallic. Cleavage prismatic. Fracture small-grained uneven. Sp. gr. 5-7 to 5.8. Its constituents are, tellurium 44-75, gold 26.75, lead 19.5, silver 8.5, sulphur 0.5. Klaproth. It occurs in veins in porphyry at Naygag in Transylvania. XX. TIN ORES. 1. Pyramidal tin ore* 1. Common tin ore, or tinstone' Colour blackish-brown. Massive, disseminated, but most frequently crystallized. Primitive form, a double four-sided pyramid, in which the angles are 133 36' and 67 42'. Secondary figures are, the primitive truncated ; a rectan- gular four-sided prism, variously truncated or acuminated, and twin crystals. Splendent, and adamantine. Fracture uneven. From semitransparent to opaque. Streak grayish- white. As hard as felspar, sometimes as quartz. Easily frangible. Sp. gr. 6.3 to 7-0. Before the blowpipe it decrepitates, and be- comes paler, and is reduced to the metallic state. Its constituents are, tin 77-5, iron 0.25, oxygen 21.5, silica 0.75. It occurs in granite, gneiss, &c. ; and in an alluvial form, in what are in Cornwall called stream works. There are only three tin districts in Europe : Cornwall, which is the most considerable ; the Erzegebirge ; and Monte Rey, in Gallicia. $ 2. Cornish tin ore, or wood-tin. Colour hair-brown. In rolled and imitative shapes. Glistening. Opaque. Softer than common tinstone. Streak gray, inclining to brown. Brittle. Sp. gr. 6.4. Its constituents are, oxide of tin 91, oxide of iron 9. Vauquelin. It occurs along with stream-tin. 2. Tin pyrites. Colour between steel-gray and brass-yellow. Massive and disseminated. Glistening and metallic. Fracture uneven. Yields easily to the knife. Brittle. Sp. gr. 4.35. Not magnetic. Before the blowpipe it exhales a sulphureous vapour, and melts easily. Its constituents are, tin 34, copper 36, iron 3, sulphur 25, earthy matter 2. Klaproth. It has been found only in Corn- wall, in granite, at St. Michael's Mount. XXI." TITANIUM ORES. T T ORE 642 ORE 1. Prismatic titanium ore, or sphene. a. Common sphene. Colours, reddish, yel- lowish, and reddish-brown. It occurs in gra- nular concretions, and crystallized in the fol- lowing forms : A low very oblique four-sided prism, bevelled or truncated ; a broad six-sided prism ; a rectangular four-sided prism ; an oblique double four-sided pyramid. Shining and adamantine. Fracture imperfect con- choidal. Streak grayish or yellowish-white. Harder than apatite. Brittle. Sp. gr. 3.4 to 3.6. Before the blowpipe it is fusible with difficulty into a brownish-black enamel. Its constituents are, oxide of titanium 46, silica 36, lime 16, water 1. Klaproth. It occurs in the syenite of Criffle, and other hills in Galloway ; in the syenite of Inverary ; on tbe south side of Loch-Ness ; the granite of Aber- deen ; the syenite of Culloden, in Inverness- shire ; in the floetz rocks of Mid-Lothian ; and at Arendal, in Norway. b. Foliated sphene. Colour yellow. Mas- sive, in straight lamellar concretions, and cry- stallized as the preceding. Lustre splendent. Cleavage double. Fracture imperfect con- choidal. Translucent. It occurs at La Por- tia, in Piedmont, St. Gothard, and Arendal. 2. Prismato- pyramidal titanium ore. a. RutUe. Colour reddish-brown. Mas- sive and crystallized. Primitive figure, a pyramid of 11 7" 2' and 84 48'. Secondary forms are, a long rectangular four-sided prism ; four-sided prism ; six-sided prism ; and aci- cular crystals. The crystals are occasionally curved. Splendent or glistening. Streak brown. Translucent. Harder than apatite. Brittle. Sp. gr. 4.255J Lowry. It is pure pxide of titanium, with a little oxide of iron. It occurs in the granite of Cairngorm, the limestone of Rannoch, and in the rocks of Ben Gloe, where it was discovered by Dr. M'Culloch. b. Iserine. Colour iron-black. In obtuse angular grains, and in rolled pieces. Splen- dent and metallic. Fracture conchoidal. Harder than felspar. Opaque. Brittle. Sp. gr. 46. Before the blowpipe it melts into a blackish -brown coloured glass, which is slightly attracted by the magnet. Its constituents are, oxide of titanium 28, oxide of iron 72- Klaproth ; or, oxide of titanium 48, oxide of iron 48, oxide of uranium 2. Thomson. It occurs embedded in gneiss, and disseminated in granite sand, along with iron-sand, in the bed of the river Don, in Aberdeenshire. c. Menachanite. Colour grayish-black. In small fiattish angular grains. Glimmering or semi-metallic. Opaque. Brittle. Sp. gr. 4.427. It is attractible by the magnet. Its constituents are, oxide of iron 51, oxide of titanium 45.25, oxide of manganese 0.25, silica 3.5. Klaproth. It is found in the valley of Manaccan in Cornwall. 3. Pyramidal titanium ore, or octohedrite. Colour passes from indigo-blue to brown. Crystallized. Its primitive form is a pyramid of 97 38' and 137 10'. The following are secondary figures ; the pyramid truncated on the extremities, and double four-sided pyra- mid variously acuminated. Lustre splendent, adamantine. Cleavage fourfold. Translucent. Harder than apatite. Brittle. Sp. gr. 3-8 to 3-9. It is oxide of titanium. It is found in Dauphiny. XXII. TUNGSTEN ORES. 1. Pyramidal tungsten, or scheel'nim. Co- lour white. Massive, and sometimes crystal- lized. The primitive form is a rather acute double four-sided pyramid. Secondary forms are, the primitive figure bevelled on the an- gles ; a very acute double four-sided pyramid ; a flat double four-sided pyramid ; a square lenticular figure ; and a flat double four-sided pyramid. Shining. Fracture uneven. Cleavage ninefold. Translucent. Harder than fluor spar. Brittle. Sp. gr. 6 to 6-1. Its consti- tuents are, oxide of tungsten 65, lime 31, silica 4 Scheele ; oxide of tungsten 75-25, lime 18-70, silica 1-56, oxide of iron 1-25, oxide of manganese 0-75. Klaproth. It oc- curs along with tin-stone and wolfram, in Cornwall ; in Sweden ; Saxony, &c. 2. Wolfram. Prismatic wolfram. Colour black. Massive and crystallized. Primitive form is an oblique four-sided prism of 120. Secondary forms are, the oblique four-sided prism, bevelled, truncated, or acuminated ; and a twin crystal. Shining. Fracture uneven. Opaque. Streak dark reddish-brown. Harder than apatite. Brittle. Sp. gr. 7-1 to 7-4. Its constituents are, tungstic acid 67, oxide of manganese 6-25, oxide of iron 18- 10, silica 1-5. Vau- quelin. It occurs in gneiss in the island of Rona of the Hebrides, and in Cornwall. XXIII. URANIUM ORES. 1. Uran ochre. a. Friable. Colour lemon-yellow. It oc- curs as a coating on pitch ore. It is composed of dull, weakly cohering particles. It feels meagre. b. Indurated. Colour straw-yellow. Massive and superimposed. Glimmering. Opaque. Soft. Sp. gr. 3-15. The yellow varieties are pure oxide of uranium. The brownish and reddish contain a little iron. It is found in Bohemia and Saxony. 2. Indivisible uranium or pitch ore. Co- lour greenish-black. Massive, renifcrm, and in distinct concretions. Shining. Hardness between apatite and felspar. Opaque. Brittle. Sp. gr. 6-4 to 6-6. Its constituents are, oxide of uranium 86-5, black oxide of iron 2-5, galena 6-0, silica 5. Klaproth. It occurs in primitive rocks. It is found in Cornwall. 3. Uranite or nran mica. Pyramidal uran mica. Colour grass-green. In flakes and crystallized. Primitive form, a pyramid, in which the angles are 95 13' and 144 56'. The secondary forms are, a rect- ORE 643 ORE angular four-sided table or short prism, and a four-sided table variously bevelled and truncated. Shining. Cleavage fourfold and rectangular. Transparent and translucent. Scratches gypsum, but not calcareous spar. Streak green. Sectile. Not flexible. Easily frangible. Sp. gr. 3-1 to 3-2. It decrepitates violently before the blowpipe on charcoal ; loses about 33 per cent, by ignition, and acquires a brass-yellow colour. Its constituents are, oxide of uranium, with a trace of oxide of lead 74-4, oxide of copper 8-2, water 15-4. Gregor. It occurs in veins in primitive rocks- It is found in Cornwall and Saxony. XXIV. WOODANIUM ORES ? Woodan pyrites. Colour dark tin-white. In vesicular massive portions. Lustre shining and metallic. Fracture uneven. Opaque. Harder than fluor, but softer than apatite. Brittle. Sp. gr. 5-J92. It was said to con- tain 20 percent, of wodanium, combined with sulphur, arsenic, iron, and nickel. It occurs at Topschau in Hungary. XXV. ZINC ORES. 1. Red aittc, or red oxide of zinc. Colour blood-red. Massive, disseminated. On the fresh fracture, shining. Cleavage single. Frac- ture conch oidal. Translucent on the edges. Easily scratched by the knife. Brittle. Streak brownish-yellow. Sp. gr. 6-22. It is soluble in the mineral acids. Its constituents are, zinc 76, oxygen 16, oxides of manganese and iron 8 Bruce. It has been found in New Jersey, North America. 2. Zinc blende. Dodecahedral zinc blende. a. Yellow. Wax-yellow, and several other colours, inclining to green. Massive, disse- minated, and crystallized in octohedrons, rhom- boidal dodecahedrons, and twin crystals. Splen- dent and adamantine. Cleavage dodecahedral, or sixfold. Translucent. Refracts single. Streak yellowish-gray. Harder than calca- reous spar. Brittle. Sp. gr. 4 to 4-2. It becomes phosphorescent by friction. Its con- stituents are, zinc 64, sulphur 20, iron 5, fluoric acid 4, silica 1, water 6. Bcrgmann. It occurs in veins, associated with galena. It is found at Clifton mine, near Tyndrum, in Perthshire, also in Flintshire. Fine specimens are found in Bohemia. 1). Brown zinc blende. 1. Foliated. Colour reddish-brown. Mas- sive, disseminated, and crystallized, in arhom- boidal dodecahedron, an octohedron, a tetra- hedron, and acicular crystals. Lustre between pearly and adamantine. Cleavage sixfold or tessular. Translucent. Streak yellowish - brown. Sp. gr. 4-048. Its constituents are, zinc 58-8, sulphur 23-5, iron 8-4, silica 7-0. Dr. Thomson. It occurs in veins and beds, in primitive and transition rocks. It is found in the Clifton lead mine, near Tyndrum ; at Gumberhead in Lanarkshire ; at Leadhills ; and in all the lead mines in England and Wales. 2. Fibrous. Colour dark reddish-brown. Massive, reniform, and in radiated concre- tions. Glistening, inclining to pearly. Opaque. Its constituents are, zinc 62, iron 3, lead 5, arsenic 1, sulphur 21, alumina 2, water 4. It occurs in Huel-Unity copper-mine in Cornwall. c. B lack zinc blende. Colour between gray- ish and velvet-black. Massive, disseminated, and crystallized in the same figures as brown blende. Shining, adamantine. Opaque. The blood-red variety is translucent on the edges and angles. Streak dark yellowish-brown. Sp. gr. 4-1665. Its constituents are, oxide of zinc 53, iron 12, arsenic 5, sulphur 26, water 4. The black blende from Naygag, besides zinc, iron, and manganese, contains a portion of auriferous silver. It occurs in veins of gneiss, in Sweden, Saxony, &c. OF THE ANALYSIS AND REDUCTION OP ORES. By consulting the table of metallic preci- pitants, and studying the peculiar habitudes of the individual metals and earths, the reader may acquire a knowledge of the methods of separating them from one another, and deter- mining the proportion of each. The limits of the present work permit me to offer merely a short account of the best modes of analyzing a few of the principal ores on the small scale, and of reducing them on the large. I. ANTIMONY. 1. Native antimony was skilfully examined by Klaproth, the parent of accurate analysis, as follows : On 100 grains of the pulverized mineral he poured strong nitric acid, which attacked it with vehemence, converting it into an oxide ; which being precipitable by water, he diluted the solution with this liquid, and then filtered. The clear liquid was treated with muriatic acid, which threw down the silver present, in the state of muriate, equiva- lent to 1 grain of the precious metal. Prus- siate of potash then indicated % of a grain of iron. The oxide of antimony was now dis- solved in muriatic acid, the solution diluted with water, and a piece of zinc being intro- duced, precipitated 98 grains of metallic anti- mony. Hence the 100 grains of native anti- mony from Andreasberg, consisted of metallic antimony, 98 silver, I iron, 0-25 99-25 2. Fibrous red antimonial ore. Klaproth digested 100 grains with muriatic acid, mixed with a few drops of nitrous, in a long-necked matrass. There was a gray residuum of 1A grains of sulphur. " The antimony contained T T 2 ORE 644 ORE in the solution was precipitated in the state of a white oxide, by diluting it with water, arid the small portion of the metal still re- maining in that fluid was afterwards entirely thrown down by means of potash. The oxide thus procured was redissolved in muriatic acid, the solution diluted with six times its quantity of water, and once more combined with such a proportion of the same solvent, as was neces- sary in order to redissolve entirely that portion of the oxide which the aftused water had pre- cipitated. After the dilute solution had, in this manner, again been rendered clear, its ingredient antimony was reproduced as metal- lic antimony, by immersing polished iron in the liquor. It weighed, when collected, edul- corated, and dried, G^ grains. Klaproth j s Analytical Essays, vol. ii. p. 143. EtogUih Translation. From the above result, and Thenavd's statement of the constitution of the oxide, Klaproth inferred, that the mineral consisted of Metallic antimony, 67-5 Oxygen, 108 Sulphur, - -19-7 98-0 3. If the pulverized sulphuret of antimony be acted on by nitric acid, with heat, and water be afterwards added, a precipitate will fall, consisting of oxide of antimony, with sul- phur and sulphate of lead. Sulphate of silver being very soluble in dilute nitric acid, will remain in the liquid. Muriate of soda will throw down the silver, without affecting the lead, if the solution be hot and somewhat dilute. The lead, if any remain, may then be precipitated by sulphate of soda in equiva- len^ quantity, or by hydrosulphuret of ammo- nia: by muriate of barytes, the sulphuric acid resulting from acidification of the sulphur may be ascertained ; and by ferroprussiate of pot- ash, the iron. On the first precipitate obtained by affusion of water, if muriatic acid be di- gested, the oxide of antimony will be taken up, and may be recovered in the metallic state, by immersing a piece of zinc or iron in the muriatic solution. Lastly, the sulphur may be separated from the sulphate of lead by ustulation. Metallic antimony is best obtained from the sulphuret, by igniting it, after careful ustula- tion, with half its weight of crude tartar. The metal will be found at the bottom of the cru- cible. Or the ustulated oxide, mixed with oil, fat, and pounded charcoal, is to be ignited till drops of the metal begin to appear ; and nitre equal to l-16th of the weight of the oxide is then to be gradually injected. Or we form the martial tegulus of antimony (anti- mony containing a little iron and sulphur), by adding 16 ounces of the sulphuret to six ounces of iron nails, ignited to whiteness in a crucible. When the whole are in fusion, inject gradu- ally two ounces of pulverized nitre ; then cover the crucible, and urge the heat for a little. Seven or eight ounces of the regulus will be found at the bottom. By repeating the fusion, and projection of nitre, two or three times, the regulus may be brought nearer to the state of pure metal. In what follows, I shall confine myself to the detail of a few ingenious and exact ana- lyses. 2. BISMUTH ORES. The following analysis of a complex me- tallic mineral by Klaproth, is peculiarly in- structive. Examination in the humid way of the bis- muthic silver ore from Schaupbach, in the Black Forest, in Suabia. (a.) Upon 300 grains of this ore he poured three ounces of nitric acid, diluted with one ounce of water. The residuum being acted on with more acid, both solutions were mixed, and evaporated to a small volume; during which process there separated from the fluid some crystalline grains, consisting of nitrate of lead. (&.) The concentrated solution had a green- ish colour. When afterwards diluted with just as much water as was requisite to redissolve that crystalline sediment, it was poured into a large quantity of water. This last immedi- ately acquired a milky appearance in a high degree, and deposited a white precipitate, which weighed 44<2 grains, when collected, lixiviated, and dried in the air, and proved, on further examination, to be oxide of bismuth. (c.) Into the liquor that had been freed from this oxide, and was entirely clear and colour- less, he then dropped muriatic acid as long as it was rendered turbid by it. The precipitate, which now fell, did not appear to be mere mu- riaie of silver; for this reason he digested it for some time with a moderately strong nitric acid. A considerable portion of it wat, thus re- dissolved, and left pure horn-silver beliind ; which, upon careful collection, and desiccation in a brisk heat, weighed 46 grains. Thus, the portion of pure silver is determined at 34^ grains. (d.} The nitric acid that had been affused upon the precipitate obtained by the muriatic (c.), yielded by dilution with much water, 32 grains more of oxidized bismuth ; which, with the preceding 44^ (6.), gave together 76 grains. In order to ascertain the proportion of reguline bismuth in this ore, he dissolved 100 grains of bismuth in nitric acid ; and, after having concentrated the solution by evapora- tion, he poured it into a large quantity of water. When, of the precipitate thus pro- duced, nothing more would fall down, on add- ing more water he collected it on the filter, washed it, and suffered it to dry perfectly in the air. It then weighed 88 grains. To the water which had been separated from it, mu- ORE 645 ORE tiatic acid was added by drops ; whereby a new precipitate ensued, weighing 32 grains, after edulcoration and drying. As, by the result of this comparative experi- ment, 100 grains of bismuth have, upon the whole, given 123 grains of oxide, it follows, that the 762 grains of oxide (rf.) obtained from 300 grains of this ore, contain 62 grains of metallic bismuth. (c. ) The remainder of the fluid was further reduced by evaporation ; and in this process muriate of lead separated from it in delicate broad striated crystals. This liquor was then combined with such a quantity of sulphuric acid as was requisite to redissolve those crys- tals, and a second time evaporated to a con- sistence of pap. The precipitate which thence ensued was sulphate of lead, weighing 19 grains, when duly collected, washed, and dried. (/.) What still remained of the solution, after its having been freed from the lead be- fore contained in it, was saturated with caustic ammonia added in excess. In this way, a brown ferruginous precipitate was produced ; which was rapidly attracted by the magnet, and weighed 14 grains, when, after previous desiccation, it had been moistened with linseed oil, and well ignited. For these we must reckon 10 grains of metallic iron. (ff.) The liquor which had been supersa- turated with ammonia, and which, by its blue colour, showed that it held copper in solu- tion, was saturated to excess with sulphuric acid. On immersing then a piece of polished iron into it, two grains of copper were de- posited. (A.) The gray residue of the ore that was left behind by the nitric acid (.), weighed, 178 grains. But when its sulphureous part had been deflagrated, in a crucible gently heated, it weighed only 140^ grains. This deter- mines the portion of sulphur at 37|- grains. (i) These 140 grains were digested with three ounces of muriatic acid, in a heat of ebul- lition ; and the process was repeated once more with 1^- ounce of the same acid. These solutions, by means of evaporation, yielded till the end muriate of lead in tender spicular, and likewise in broad striated, crystals ; which, when again dissolved in the requisite quantity of boiling water, then combined with sulphuric acid, and evaporated, yielded 89 grains of sul- phate of lead. Thus, the whole quantity of this sulphate, including the 19 grains men- tioned at (c.) amounted to 188 grains; for which, according to comparative experiments, 76 grains of reguline lead must be put in the computation. (fc.) That portion of the ore examined, which still remained after all the constituent parts before mentioned had been discovered, consisted merely of the gray quartzose matrix ; the weight of which, in the ignited state, amounted to 70 grains. Therefore, these 300 grains of bismuthic silver ore decomposed into Exelu.ofmatt. Lead, (j) 76-00 3300 Bismuth, ( 1.25 Saltpetre? _) 26-00 The principle in pollen, intermediate be- tween gluten and albumen, has been named by Dr. John, Pollenin. It is yellow, without taste and smell ; in- soluble in water, alcohol, ether, fat, and volatile oils, and petroleum. It burns with flame. On exposure to air, it assumes the smell and taste of cheese, and soon becomes putrid with disengagement of ammonia. POLYCHROITE. The colouring matter of saffron. POLYMIGNITE. A new mineral found sometimes in the zirconian sienite of Fre- drickswarns. It is black, brilliant, and crys- tallized in small prisms, long, thin, with a rectangle, the edges of which are commonly replaced by one or several planes. Sp. gr. 4-806. It scratches glass, but cannot be scratched by steel. Fracture conch oidal, with- out indications of cleavage. The surface of the crystals has vivid lustre, almost metallic. The fracture also resembles the surface, pos- sessing a brilliancy far beyond what is common in minerals. At the blowpipe it suffers no change. With borax, it melts easily, and forms a glass coloured with iron. With more borax, it becomes opaque and of an orange colour. Its composition is extraordinary : Titanic acid, 46-3 Zirconia, 14-4 Oxide of iron, . 12-2 Lime, .... 4-2 Oxide of manganese, 2-7 Oxide of cerium, 5-0 Yttria, . .11-5 Traces of magnesia, potash, silica, oxide of tin, 96-3 Berzelius ; Annales de Chim. xxxi. 405. POLYHALLITE. A mineral in masses of a fibrous texture. Sp. gr. 277- Pearly lustre. Its constituents are, hydrous sulphate of lime 28-25 ; anhydrous sulphate 22-42 ; anhydrous sulphate of magnesia 20-03; sulph. of potash 27-7 ; muriate of soda 0-19 ; red oxide of iron 0-34. It occurs at Ischel in Upper Austria. POMPHOLIX. White oxide of zinc. PONDEROUS SPAR. See HEAVY SPAR. PORCELAIN EARTH. See CLAY. PORCELAIN is the most beautiful and the finest of all earthen wares. The art of making porcelain is one of those in which Europe was long excelled by oriental nations. The first porcelain that was seen in Europe was brought from Japan and China, The whiteness, transparency, fineness, neat- ness, elegance, and even the magnificence of this pottery, which soon became the ornament of sumptuous tables, did not fail to excite the admiration and industry of Europeans. Father Entrecolles, missionary at China, sent home a summary description of the process by which the inhabitants of that country make their porcelain, and also a small quantity of the materials which they employ in its composition. He said, that the Chinese composed their porcelain of two ingredients, one of which is a hard stone or rock, called by them petuntse, which they carefully grind to a very fine powder ; and the other, called by them kaolin, is a white earthy substance, which they mix intimately with the ground petuntse. Reaumur examined both these matters ; and having exposed them separately to a violent fire, he discovered that the petuntse had fused without addition, and that the kaolin had given no sign of fusibility. He afterward mixed these matters, and formed cakes of them, which, by baking, were converted into porcelain similar to that of China. See KAOLIN, PETUNTSE, and POTTERY. PORCELAIN OF REAUMUR. Reau- mur gave the quality of porcelain to glass ; that is, he rendered glass of a milky colour, semitransparent, so hard as to strike fire with steel, infusible, and of a fibrous grain, by means of cementation. The process, which he published, is not difficult. Common glass, such as that of which wine bottles are made, succeeds best. The glass vessel which is to be converted into porcelain is to be enclosed in a baked earthen case or seggar. The vessel and case are to be filled with a cement composed of equal parts of sand and powdered gypsum or plaster; and the whole is to be put into a potter's kiln, and to remain there during the baking of common earthenware ; after which the glass vessel will be found transformed into such a matter as has been described. PORPHYRY is a compound rock, having a basis, in which the other contemporaneous constituent parts are imbedded. The base is sometimes clay-stone, sometimes hornstone, sometimes compact felspar ; or pitchstone, pearlstone, and obsidian. The imbedded parts are most commonly felspar and quartz, which are usually crystallized more or less perfectly, and hence they appear sometimes granular. According to Werner, there are two distinct porphyry formations ; the oldest occurs POT 668 POT in gneiss, in beds of great magnitude ; and also in mica-slate and clay-slate. Between Blair in A thole and Dalnacardoch, there is a very fine example of a bed of porphyry-slate in mica. The second porphyry formation is much more widely extended. It consists principally of clay porphyry, while the former consists chiefly of hornstone porphyry and felspar porphyry. It sometimes contains considerable repo- sitories of ore, in veins. Gold, silver, lead, tin, copper, iron, and manganese occur in it ; but chiefly in the newer porphyry, as happens with the Hungarian mines. It occurs in Arran, and in Perthshire between Dalnacardoch and Tummel-bridge. PORTLAND STONE. A compact sand, stone from the Isle of Portland. The cement is calcareous. POTASH, commonly called the vegetable alkali, because it is obtained in an impure state by the incineration of vegetables. It is the hydrated protoxide of potassium. Table of the saline product of one thousand Ibs. of ashes of the following vegetables : Saline products. Stalks of Turkey > IQ ^ wheat or maise, { l Stalks of sun- 7 <*An flower, J 349 Vine branches, 162-6 Elm, 166 Box, 78 Sallow, 102 Oak, 111 Aspen, 61 Beech, 219 Fir, 132 Fern out in August, 1 Wormwood, 748 Fumitory, 360 Heath, 1 1 5 Wildenheim. On these tables Kirwan makes the following remarks : 1. That in general weeds yield more ashes, and their ashes much more salt, than woods; and that consequently, as to salts of the vegetable alkali kind, as potash, pearl-ash, cashup, &c. neither America, Trieste, nor the northern countries, have any advantage over Ireland. 2. That of all weeds fumitory produces most salt, and next to it wormwood. But if we attend only to the quantity of salt in a given weight of ashes, the ashes of wormwood con- tain most. Trifblium fibrinum also produces more ashes and salt than fern. The process for obtaining pot and pearl- ash is given by Kirwan, as follows : 1. The weeds should be cut just before they seed, then spread, well dried, and gathered clean. 2. They should be burned within doors on a grate, and the ashes laid in a chest as fast as they are produced. If any charcoal be visible, it should be picked out, and thrown back into the fire. If the weeds be moist, much coal will be found. A close smothered fire, which has been recommended by some, is very prejudicial. 3. They should be lixiviated with twelve times their weight of boiling water. A drop of the solution of corrosive sublimate will im- mediately discover when the water ceases to take up any more alkali. The earthy matter that remains is said to be a good manure for clayey soils. 4. The ley thus formed should be evapo- rated to dryness in iron pans. Two or three at least of these should be used, and the ley, as fast as it is concreted, passed from the one to the other. Thus, much time is saved, as weak leys evaporate more quickly than the stronger. The salt thus produced is of a dark colour, and contains much extractive matter, and being formed in iron pots is called pot- ash. 5. This salt should then be carried to a re- verberatory furnace, in which the extractive matter is burnt off, and much of the water dissipated : hence it generally loses from ten to fifteen per cent, of its weight. Particular care should be taken to prevent its melting, as the extractive matter would not then be per- fectly consumed, and the alkali would, form such a union with the earthy parts as could not easily be dissolved. Kirwan adds this caution, because Dr. Lewis and Mr. Dossie have inadvertently directed the contrary. This salt thus refined is called pearl-ash, and must be the same as the Dantzic pearl-ash. To obtain this alkali pure, Berthollet re- commends, to evaporate a solution of potash, made caustic by boiling with quicklime, till it becomes of a thickish consistence ; to add about an equal weight of alcohol, and let the mixture stand some time in a close vessel. Some solid matter, partly crystallized, will collect at the bottom; above this will be a small quantity of a dark-coloured fluid ; and on the top another lighter. The latter, se- parated by decantation, is to be evaporated quickly in a silver basin in a sand-heat. Glass, or almost any other metal, would be corroded by the potash. Before the evapora- tion has been carried far, the solution is to be removed from the fire, and suffered to stand at rest ; when it will again separate into two fluids. The lighter, being poured off, is again to be evaporated with a quick heat ; and on standing a day or two in a close vessel, it will deposit transparent crystals of pure potash. If the liquor be evaporated to a pellicle, the potash will concrete without regular crystal- lization. In both cases a high-coloured liquor is separated, which is to be poured off; and the potash must be kept carefully secluded from air. POT 669 POT A perfectly pure solution of potash will remain transparent on the addition of lime- water, show no effervescence with dilute sul- phuric acid, and not give any precipitate on blowing air from the lungs through it by means of a tube. Pure potash for experimental purposes may most easily be obtained by igniting cream of tartar in a crucible, dissolving the residue in water, filtering, boiling with a quantity of quicklime, and after subsidence, decanting the clear liquid, and evaporating in a loosely covered silver capsule, till it flows like oil, and then pouring it out on a clean iron plate. A solid white cake of pure hydrate of potash is thus obtained, without the agency of alco- hol. It must be immediately broken into fragments, and kept in a well-stoppered phial. As 100 parts of subcarbonate of potash are equivalent to about 70 of pure concentrated oil of vitriol, if into a measure tube, graduated into 100 equal parts, we introduce the 70 grains of acid, and fill up the remaining space with water, then we have an alkalimeter for estimating the value of commercial pearl-ashes, which, if pure, will require for 100 grains one hundred divisions of the liquid to neutralize them. If they contain only 60 per cent, of genuine subcarbonate, then 100 grains will require only 60 divisions, and so on. When the alkalimeter indications are required in pure or absolute potash, such as constitutes the basis of nitre, then we must use 102 grains of pure oil of vitriol, along with the requisite bulk of water to fill up the volume of the graduated tube. The hydrate of potash, as obtained by the preceding process, is solid, white, and ex- tremely caustic ; in minute quantities, chang- ing the purple of violets and cabbage to a green, reddened litmus to purple, and yellow turmeric to a reddish -brown. It rapidly at- tracts humidity from the air, passing into the oil of tartar per deliquium of the chemists ; a name, however, also given to the deliquesced subcarbonate. Charcoal applied to the hy- drate of potash at a cherry-red heat gives birth to carburetted hydrogen, and an alkaline subcarbonate; but at a heat bordering on whiteness, carburetted hydrogen, carbonous oxide, and potassium, are formed. Several metals decompose the hydrate of potash, by the aid of heat; particularly potassium, so- dium, and iron. The fused hydrate of potash consists of 6 protoxide of potassium + 1.125 water =: 7-125, which number represents the compound prime equivalent. It is used in surgery, as the potential cautery for forming eschars; and it was formerly employed in medicine diluted with broths as a lithontriptic. In chemistry, it is very extensively employed, both in manufactures and as a reagent in ana- lysis. It is the basis of all the common soft soaps. The oxides of the following metals are soluble in aqueous potash : Lead, tin-, nickel, arsenic, cobalt, manganese, zinc, an- timony, tellurium, tungsten, molybdenum. For the sulphuret, see SULPHUR. POTASSIUM. If a thin piece of solid hydrate of potash be placed between two discs of platinum, connected with the extremities of a voltaic apparatus of 200 double plates, four inches square, it will soon undergo fusion ; oxygen will separate at the positive surface, and small metallic globules will appear at the ne- gative surface. These form the marvellous substance potassium, first exhibited to the world by Sir H. Davy, early in October 1807. If iron turnings be heated to whiteness in a curved gun -barrel, and potash be melted and made slowly to come in contact with the turn- ings, air being excluded, potassium will be formed, and will collect in the cool part of the tube. This method of procuring it was dis- covered by MM. Gay Lussac and Thenard in 1808. It may likewise be produced by ig- niting potash with charcoal, as M. Curaudau showed the same year. M. Brunner, by acting on calcined tartar in a bottle of wrought iron, has succeeded in obtaining potassium at a comparatively mo- derate heat. The bottle is spheroidal, about half an inch in thickness, and capable of hold- ing about a pint of water; a bent gun-barrel of 10 or 12 inches in length screws into the mouth of the bottle. The bottle well luted over with fire-clay, is set in a strong air fur- nace, so as the tube may dip down externally beneath the surface of naphtha contained in a cylindric copper vessel, standing in a tub con- taining ice and water. The top of the naph- tha vessel has a cover fixed on it, pierced with a hole to receive the end of the gun-barrel ; and from the side of the upper part of the vessel, a small tube goes off at right angles to let the air and vapours escape. It is advan- tageous to mix a little ground charcoal with the tartar previously calcined in a covered vessel, in the same iron bottle for example. Nearly 300 grains of potassium have been procured by this apparatus from 24 ounces of crude tartar. BlUioth. Universelle, xxii. 36. Potassium is possessed of very extraordinary propei ties. It is lighter than water; its sp. gr. being 0.865 to water 1.0. At common tem- peratures it is solid, soft, and easily moulded by the fingers. At 150 F. it fuses, and in a heat a little below redness it rises in vapour. It is perfectly opaque. When newly cut, its colour is splendent white, like that of silver, but it rapidly tarnishes in the air. To pre- serve it unchanged, we must enclose it in a small phial, with pure naphtha. It conducts electricity like the common metals. When thrown upon water, it acts with great violence, and swims upon the surface, burning with a beautiful light of a red colour, mixed with violet. The water becomes a solution of pure potash. When moderately heated in the air, it inflames, burns with a red light, and throws POT 670 POT off alkaline fumes. Placed in chlorine, it spontaneously burns with great brilliancy. On all fluid bodies which contain water, or much oxygen or chlorine, it readily acts ; and in its general powers of chemical combination, says its illustrious discoverer, potassium may be compared to the alkahest, or universal sol- vent, imagined by the alchemists. Potassium combines with oxygen in differ- ent proportions. When potassium is gently heated in common air or in oxygen, the result of its combustion is an orange-coloured fusible substance. For every grain of the metal con- sumed, about 1-jZg- cubic inches of oxygen are condensed. To make the experiment ac- curately, the metal should be burned in a tray of platina covered with a coating of fused muriate of potash. The substance procured by the combustion of potassium at a low temperature was first observed in October, 1807, by Sir H. Davy, who supposed it to be the protoxide ; but MM. Gay Lussac and Thenard, in 1810, showed that it was in reality the deutoxide or peroxide. When it is thrown into water, oxygen is evolved, and a solution of the protoxide re- sults, constituting common aqueous potash. When it is fused, and brought in contact with combustible bodies, they burn vividly, by the excess of its oxygen. If it be heated in car- bonic acid, oxygen is disengaged, and common subcarbonate of potash is formed. When it is heated very strongly upon pla- tina, oxygen gas is expelled from it, and there remains a difficultly fusible substance of a gray colour, vitreous fracture, soluble in water with- out effervescence, but with much heat. Aque- ous potash is then produced. The above ignited solid is protoxide of potassium, which becomes pure potash by combination with the equi- valent quantity of water. When we produce potassium with ignited iron-turnings and pot- ash, much hydrogen is disengaged from the water of the hydrate, while the iron becomes oxidized from the residuary oxygen. By heat- ing together pure hydrate of potash and bo- racic acid, Sir H. Davy obtained from ] 7 to 18 of water from 100 parts of the solid alkali. By acting on potassium with a very small quantity of water, or by heating potassium with fused potash, the protoxide may also be obtained. The proportion of oxygen in the protoxide is determined by the action of potas- sium upon water. 8 grains of potassium pro- duce from water about 9|- cubic inches of hy- drogen; and for these the metal must have fixed 4 cubic inches of oxygen. But as 100 cubic inches of oxygen weigh 33-9 gr. 4& will weigh 1.61. Thus, 9.61 gr. of the protoxide will contain 8 of metal ; and 100 will contain 83.25 metal +16.75 oxygen. From these data, the prime of potassium comes out 4.909 ; and that of the protoxide 5.969. Sir H. Davy adopts the number 75 for potassium, corre- sponding to 50 on the oxygen scale. When potassium is heated strongly in a small quantity of common air, the oxygen of which is not sufficient for its conversion into potash, a substance is formed of a grayish co- lour, which, when thrown into water, effer- vesces without taking fire. It is doubtful whether it be a mixture of the protoxide and potassium, or a combination of potassium with a smaller proportion of oxygen than exists in the protoxide. In this case it would be a sub- oxide, consisting of 2 primes of potassium = 10 + 1 of oxygen =.11. When thin pieces of potassium are intro- duced into chlorine, the inflammation is very vivid ; and when potassium is made to act on chloride of sulphur, there is an explosion. The attraction of chlorine for potassium is much stronger than the attraction of oxygen for the metal. Both of the oxides of potas- sium are immediately decomposed by chlorine, with the formation of a fixed chloride, and the extrication of oxygen. The combination of potassium and chlorine is the substance which has been improperly called muriate of potash, and which, in com- mon cases, is formed, by causing liquid mu- riatic acid to saturate solution of potash, and then evaporating the liquid to dryness and ig- niting the solid residuum. The hydrogen of the acid here unites to the oxygen of the al- kali, forming water, which is exhaled ; while the remaining chlorine and potassium com- bine. It consists of 5 potassium + 4.5 chlo- rine. Potassium combines with hydrogen, to form potassuretted hydrogen, a spontaneously in- flammable gas, which comes over occasionally in the production of potassium by the gun- barrel experiment. MM. Gay Lussac and Thenard describe also a solid compound of the same two ingredients, which they call a hydruret of potassium. It is formed by heat- ing the metal a long while in the gas, at a temperature just under ignition. They de- scribe it as a grayish solid, giving cut its hy- drogen on contact with mercury. When potassium and sulphur are heated together, they combine with great energy, with disengagement of heat and light even in vacuo. The resulting sulphuret of potassium is of a dark gray colour. It acts with great energy on water, producing sulphuretted hy- drogen, and burns brilliantly when heated in the air, becoming sulphate of potash. It con- sists of 2 sulphur -\- 5 potassium, by Sir H. Davy's experiments. Potassium has so strong an attraction for sulphur, that it rapidly sepa- rates it from hydrogen. If the potassium be heated in the sulphuretted gas, it takes fire and burns with great brilliancy ; sulphuret of potassium is formed, and pure hydrogen is set free. Potassium and phosphorus enter into union with the evolution of light ; but the mutual action is feebler than in the preceding com- POT 671 POT pound. The phosphuret of potassium, in its common form, is a substance of a dark cho- colate colour, but when heated with potassium in great excess, it becomes of a deep gray co- lour, with considerable lustre. Hence it is probable, that phosphorus and potassium are capable of combining in two proportions. The phosphuret of potassium burns with great bril- liancy, when exposed to air, and when thrown into water produces an explosion, in conse- quence of the immediate disengagement of phosphuretted hydrogen. Charcoal which has been strongly heated in contact with potassium effervesces in water, rendering it alkaline, though the charcoal may be previously exposed to a temperature at which potassium is volatilized. Hence, there is probably a compound of the two formed by a feeble attraction. Of all known substances, potassium is that which has the strongest attraction for oxygen ; and it produces such a condensation of it, that the oxides of potassium are denser than the metal itself. Potassium has been skilfully used by Sir H. Davy and MM. Gay Lussac and Thenard, for detecting the presence of oxygen in bodies. A number of substances, undecorrposable by other chemical agents, are readily decomposed by this substance. Ele- ments of Chemical Phil, by Sir H. Davy. POTASSIUM (IODIDE or). See ACID (HYDRIODIC). POTTERY. The art of making pottery is intimately connected with chemistry, not only from the great use made of earthen ves- sels by chemists, but also because all the pro- cesses of this art, and the means of perfecting it, are dependent on chemistry. The process of manufacturing stoneware, according to Dr. Watson, is as follows : Tobacco-pipe clay from Dorsetshire is beaten much in water. By this process, the finer parts of the clay remain suspended in the water, while the coarser sand and other impurities fall to the bottom. The thick liquid, consisting of water and the finer parts of the clay, is farther purified by passing it through hair and lawn sieves, of different degrees of fineness. After this, the liquid is mixed (in various proportions for various wares), with another liquor, of as nearly as may be the same density, and consisting of flints calcined, ground, and suspended in water. The mixture is then dried in a kiln ; and being afterward beaten to a proper temper, it becomes fit for being formed at the wheel into dishes, plates, bowls, &c. When this ware is to be put into the furnace to be baked, the several pieces of it are placed in the cases made of clay, called seggars, which are piled one upon another, in the dome of the furnace. A fire is then lighted ; and when the ware is brought to a proper temper, which happens in about forty-eight hours, it is glazed by com- mon salt. The salt is thrown into the furnace, through holes in the upper part of it, by the heat of which it is instantly converted into 3 thick vapour ; which, circulating through the furnace, enters the seggar through holes made in its side, (the top being covered to prevent the salt from falling on the ware) ; and at- taching itself to the surface of the ware, it forms that vitreous coat upon the surface which is called its glaze. The yellow or queen's-ware is made of the same materials as the flint-ware ; but the pro- portion in which the materials are mixed is not the same, nor is the ware glazed in the same way. The flint-ware is generally made of four measures of liquid flint, and of eighteen of liquid clay. The yellow ware has a greater proportion of clay in it. In some manufac- tories they mix 20, and in others 24 measures of clay, with 4 of flint. These proportions, if estimated by the weight of the materials, would probably give for the flint-ware about 3 cwt. of clay to 1 cwt. of flint, and for the yellow ware somewhat more clay. The pro- portion, however, for both sorts of ware de- pends very much upon the nature of the clay, which is very variable even in the same pit. Hence a previous trial must be made of the quality of the clay, by burning a kiln of the ware. If there be too much flint mixed with the clay, the ware, when exposed to the air after burning, is apt to crack ; and if there be too little, the ware will not receive the proper glaze from the circulation of the salt vapour. This glaze, even when it is most perfect, is in appearance less beautiful than the glaze on the yellow ware. The yellow glaze is made by mixing toge- ther in water, till it becomes as thick as cream, 112 Ib. of white lead, 24 Ib. of ground flint, and 6 Ib. of ground flint-glass. Some manu- factories leave out the glass, and mix only 801b. of white lead with 201b. of ground flint ; and others doubtless observe different rules, of which it is very difficult to obtain an ac- count. The ware before it is glazed is baked in the fire. By this means it acquires the property of strongly imbibing moisture. It is therefore dipped in the liquid glaze, and suddenly taken out : the glaze is imbibed into its pores, and the ware presently becomes dry. It is then exposed a second time to the fire, by which means the glaze it has imbibed is melted, and a thin glassy coat is formed upon its surface. The colour of this coat is more or less yellow, according as a greater or less proportion of lead has been used. The lead is principally instrumental in producing the glaze, as well as in giving it the yellow colour ; for lead, of all the substances hitherto known, has the great- est power of promoting the vitrification of the substances with which it is mixed. The flint serves to give a consistence to the lead during the time of its vitrification, and to hinder it from becoming too fluid, and running down PRE 672 PUM the sides of the ware, and thereby leaving them unglazed. The yellowish colour which lead gives when vitrified with flints, may be wholly changed by very small additions of other mineral sub- stances. Thus, to give one instance, the beautiful bjack glaze, which is fixed on one sort of the ware made at Nottingham, is com- posed of 21 parts by weight of white lead, of 5 of powdered flints, and of 3 of manganese. The queen's-ware at present is much whiter than formerly. The coarse stoneware made at Bristol con- sists of tobacco-pipe clay and sand, and is glazed by the vapour of salt, like Stafford- shire flint-ware ; but it is far inferior to it in beauty. POTENTIAL CAUTERY. Caustic pot- ash. POTSTONE, or LAPIS OLLARIS. Colour greenish-gray. Massive, and in gra- nular concretions. Glistening. Fracture curved, foliated. Translucent on the edges. Streak white. Soft. Sectile. Feels greasy. Somewhat tough. Sp. gr. 2-8. Its constitu- ents are, silica 39, magnesia 16, oxide of iron 10, carbonic acid 20, water 10. It occurs in thick beds in primitive slate. It is found abundantly on the shores of the lake Como in Lombardy. It is fashioned into culinary vessels in Greenland. It is a subspecies of the rhomboidal mica of Professor Jameson. POWDER or ALGOROTH. The white oxide of antimony, thrown down from the mu- riate, by water. PRASE. Colour leek-green. Massive, seldom crystallized. Its forms are, the six- sided prism, and the six-sided pyramid. Lus- tre shining. Fracture conchoidal. Translu- cent. Hard. Tough. Sp. gr. 2.67. Its constituents are, silica 98.5, alumina, with magnesia, 0-5, and oxide of iron 1 Bucholz. It occurs in mineral beds composed of magne- tic ironstone, galena, &c. It is found in the island of Bute, and in Borrodale. PRECIPITANTS. See METALS, and MINERAL WATERS. PRECIPITATE, AND PRECIPITA- TION. When a body dissolved in a fluid is either in whole or in part made to separate and fall down in the concrete state, this falling down is called precipitation, and the matter thus separated is called a precipitate. See WATERS (MINERAL), and METALS. PRECIPITATE, per se. Red oxide of mercury, by heat. - PREHNITE. Prismatic prehnite ; of which there are two sub-species, the foliated and the fibrous. 1. Foliated. Colour apple-green. Massive in distinct concretions, and sometimes crystal- lized. The primitive form is an oblique four- sided prism of 103 and 77. The secondary forms are, an oblique four-sided table, an irre- gular eight-sided table, an irregular six-sided table, and a broad rectangular four-sided prism. Shining. Fracture fine-grained uneven. Trans- lucent. Hardness from felspar to quartz. Easily frangible. Sp. gr. 2.8 to 3.0. It melts with intumescence into a pale-green or yellow glass. It does not gelatinize with acids. Its constituents are, silica 43-83, alumina 30-33, lime 18-33, oxide of iron 5-66, water 1-83. Klaproth. It occurs in France, in the Alps of Savoy, and in the Tyrol. It is said to become electric by heating. Beautiful varieties are found in the interior of Southern Africa. 2. Fibrous Frehnite. Colour siskin-green. Massive, in distinct concretions, and crystal- lized in acicular four-sided prisms. Glisten- ing, pearly. Translucent. Easily frangible. Sp. gr. 2-89. It melts into a vesicular enamel. It becomes electric by heating. Its constitu- ents are, silica 42. 5, alumina 28-5, lime 20-44, natron and potash 0-75, oxide of iron 3, water 2. Laugicr. It occurs in veins and cavities in trap-rocks near Beith in Ayrshire, Bishop- town in Renfrewshire, at Hartfield near Paisley, and near Frisky-hall, Old Kilpa- trick : in the trap -rocks round Edinburgh, &c. PRINCE'S METAL. A species of cop- per alloy, in which the proportion of zinc is more considerable than in brass. PROSTATE CONCRETIONS. See CALCULI. PRUSSIAN ALKALI. SeaAciD(FER- ROPRUSSIC). PRUSSIAN BLUE. See IROK and the above ACID. PRUSSIC ACID. See Acm (PRUS- sic). PSEUDOLITE. A mineral having a close affinity to the pseudomorphous crystals of steatite. Annals of Phil x. 314. PULMONARY CONCRETIONS, con- sist of carbonate of lime, united to a mem- branous or animal matter. By Mr. Comp- ton's analysis, Phil. Mag. vol. xiii. 100 parts contain, Carbonate of lime, 82 Animal matter and water, 18 Disease proceeding from this cause, (and I believe it to be a frequent prelude and conco- mitant of ulcerated lungs), might be probably benefited by the regular inhalation of aque- ous vapour mixed with that of acetic acid or vinegar. PUMICE. A mineral of which there are three kinds, the glassy, common, and por- phyritic. 1. Glassy pumice. Colour smoke-gray. Vesicular. Glistening, pearly. Fracture pro- miscuous fibrous. Translucent. Between hard and semi-hard. Very brittle. Feels rough, sharp, and meagre. Sp. gr. 0-378 to 1-44. It occurs in beds in the Lipari Islands. 2. Common pumice. Colour nearly white. Vesicular. Glimmering, pearly. Fracture PYR 673 PYR fibrous. Translucent on the edges. Semi- hard. Very brittle. Meagre and rough. Sp. gr, 0-752 to 914. It melts into a gray- coloured slag. Its constituents are, silica 77 - 5, alumina 17-5, natron and potash 3, iron mixed with manganese 1-75. Klaproth. It occurs with the preceding. 3. Porphyritlc pumice. Colour grayish- white. Massive. Minutely porous. Glim- mering and pearly. Sp. gr. 1.661. It con- tains crystals of felspar, quartz, and mica. It is associated with claystone, obsidian, pearl- stone, and pitchstone-porphyry. It occurs in Hungary, at Tokay, &c. PUS. The fluid of ulcers or abscesses. PUTREFACTION. The spontaneous decomposition of such animal or vegetable matters as exhale a fetid smell is called putre- faction. The solid and fluid matters are re- solved into gaseous compounds and vapours which escape, and into an earthy residuum. See ADIPOCERE and FERMENTATION, of which genus putrefaction is merely a species. As the grand resolvent of organic matter is water, its abstraction by drying, or fixation by cold, by salt, sugar, spices, &c. will coun- teract the process of putrefaction. The atmo- spheric air is also active in putrefaction ; hence, its exclusion favours the preservation of food ; on which principle, some patents have been obtained. PUZZOLANA. A kind of volcanic ashes found at Vesuvius, Pompeii, &c. used in water-mortar, or in hydraulic lime. The red or white ashes are reckoned the best. These ashes need to be mixed with lime. See CE- MENTS. M. Bruyere finds that an excellent artificial puzzolana may be obtained by heat- ing a mixture of three parts clay, and one part slacked lime, by measure, for some hours to redness. Annalcs de Mines, ix. 550. PYRALLOLIT. A new mineral belong- ing to the talc family, found in the lime quarry of Storgard, at the point of Pargas in Finland. It has the singular property of blackening before the blowpipe at a low red heat ; and of afterwards becoming white at a higher temperature. It occurs crystallized in quadrangular prisms of which the angles are 94 36' and 85 24'. Surface dull. Lustre greasy. Fracture dull-earthy. Sp.gr. 2-57- In powder phosphorescent with heat, emitting a bright bluish light. Its constituents are, silica 56-62, magnesia 23-38, alumina 13-38, lime 3-38, protox. manganese 0.99, peroxide of iron 0-09, water 3-58, bituminous matter and loss 6-38 in 100. M. Julin^ Annals of Phil i. 235. PYRENEITE. Colour grayish - black. Massive, and crystallized in rhomboidal dode- cahedrons. Glistening, and metal-like. Frac- ture uneven. Opaque. Hard. Sp. gr. 2-5 ? It melts with intumescence, into a yellowish- green vesicular enamel. Its constituents are, silica 43, alumina 16, lime 20, oxide of iron 16, water 4. Vauquelln. It occurs in primi- tive limestone, in the Pic of Eres-Lids, near Bareges, in the French Pyrenees. PYRITES. Native compounds of metal with sulphur. See the particular metallic ORES- PYROGOM. A variety of diopside. PYROMETER. The most celebrated instrument for measuring high temperatures is that invented by the late Mr. Wedgewood, founded on the principle, that clay progres- sively contracts in its dimensions, as it is pro- gressively exposed to higher degrees of heat. He formed his white porcelain clay into small cylindrical pieces, in a mould, which, when they were baked in a dull red heat, just fitted into the opening of two brass bars, fixed to a brass plate, so as to form a tapering space be- tween them. This space is graduated : and the farther the pyrometric clay gauge can en- ter, the greater heat does it indicate. The two converging rules are placed at a distance of 0.5 of an inch at the commencement of the scale, and of 0-3 at the end. Mr. Wedgewood sought to establish a cor- respondence between the indications of his pyrometer and those of the mercurial thermo- meter, by employing a heated rod of silver, whose expansions he measured, as their con- necting link. The clay-piece and silver rod were heated in a muffle. When the muffle appeared of a low red heat, such as was judged to come fully within the province of his thermometer, it was drawn forward toward the door of the oven ; and its own door being then nimbly opened by an assistant, Mr. Wedgewood pushed the silver piece as far as it would go. But as the divi- sion which it went to could not be distinguish- ed in that ignited state, the muffle was lifted out, by means of an iron rod passed through two rings made for that purpose, with care to keep it steady, and avoid any shake that might endanger the displacing of the silver piece. When the muffle was grown sufficiently cold to be examined, he noted the degree of expansion which the silver piece stood at, and the degree of heat shown by the thermometer pieces measured in their own gauge ; then re- turned the whole into the oven as before, and repeated the operation with a stronger heat, to obtain another point 'of correspondence on the two scales. The first was at 2-J of his thermometer, which coincided with 66 of the intermediate one; and as each of these last had been be- fore found to contain 20 of Fahrenheit's, the 66 will contain 1320 ; to which add 50, the degree of his scale to which the (0) of the in- termediate thermometer was adjusted, and the sum 1370 will be the degree of Fahrenheit's corresponding to his 2^. The second point of coincidence was at 6 of his, and 92 of the intermediate ; which 92 PYR 674 PYR being, according to the above ^proportion, equivalent to 1840 of Fahrenheit^ add 50 as before to this number, and his 6^ is found to fall upon the 1890th degree of Fahrenheit. It appears hence that an interval of four de- grees upon Mr. Wedgewood's thermometer is equivalent to an interval of 520 upon that of Fahrenheit ; and, consequently, one of the former to 130 of the latter ; and that the (0) of Mr. Wedgewood corresponds to 1077^ of Fahrenheit. From these data it is easy to reduce either scale to the other through their whole range ; and from such reduction it will appear, that an interval of near 480 remains between them, which the intermediate thermometer serves as a measure for; that Mr. Wedge- wood's includes an extent of about 32000 of Fahrenheit's degrees, or about 54 times as much as that between the freezing and boil- ing points of mercury, by which mercurial ones are naturally limited ; that if the scale of Mr. Wedgewood's thermometer be produced downward in the same manner as Fahrenheit's has been supposed to be produced upward, for an ideal standard, the freezing point of water would fall nearly on 8 below (0) of Mr. Wedge- wood's, and the freezing point of mercury a little below 8^ ; and that, therefore, of the extent of row measurable heat, there are about 5-10ths of a degree of his scale from the freez- ing of mercury to the freezing of water ; 8 from the freezing of water to full ignition ; and 160 above this to the highest degree he has hitherto attained. Mr. Wedgewood concludes his account with the following table of the effects of heat on different substances, according to Fahren- heit's thermometer, and his own. Extremity of the scale ) of his thermometer j Greatest heat of his ^ small air furnace $ Cast-iron melts Greatest heat of a com- ) mon smith's forge ) Welding heat of iron, } greatest Welding heat of iron, least Fine gold melts Fine silver melts Swedish copper melts Brass melts Heat by which his ) enamel colours are V burnt on J Red heat fully visible > in day-light \ Red heat fully visible ? in the dark Mercury boils Water boils Fahr. Wedg. 32277 240 21877 160 17977 130 17327 125 13427 95 12777 90 5237 4717 4587 3807 1857 32 28 27 21 6 1077 o 947 1 212 Vital heat . 97 Water freezes 32 Proof spirit freezes The point at which mercury "\ congeals, consequently f 40 the limit of mercurial f v thermometers, about J In a scale of HEAT drawn up in this man- ner, the comparative extents of the different departments of this grand and universal agent are rendered conspicuous at a single glance of the eye. We see at once, for instance, how small a portion of it is concerned in animal and vegetable life, and in the ordinary opera- tions of nature. From freezing to vital heat is barely a five-hundredth part of the scale ; a quantity so inconsiderable, relatively to the whole, that in the higher stages of ignition ten times as much might be added or taken away without the least difference being dis- cernible in any of the appearances from which the intensity of fire has hitherto been judged of. Hence, at the same time, we may be convinced of the utility and importance of a physical measure for these higher degrees of heat, and the utter insufficiency of the com- mon means of discriminating and estimating their force. Mr. Wedgewood adds, that he has often found differences, astonishing when considered as a part of this scale, in the heats of his own kilns and ovens, without being perceivable by the workmen at the time, or till the ware was taken out of the kiln. Since dry air augments in volume 3-8ths for 180 degrees, and, since its progressive rate of expansion is probably uniform by uni- form increments of heat, a pyrometer might easily be constructed on this principle. Form a bulb and tube of platinum, of exactly the same form as a thermometer, and connect with the extremity of the stem, at right angles, a glass tube of uniform calibre, filled with mercury, and terminating below in a recurved bulb, like that of the Italian baro. meter. Graduate the glass tube into a series of spaces equivalent to 3-8ths of the total volume of the capacity of the platina bulb, with 3-4ths of its stem. The other fourth may be supposed to be little influenced by the source of heat. On plunging the bulb and 2-3ds of the stem into a furnace, the depression of the mercury will indicate the degree of heat. As the movement of the column will be very considerable, it will be scarcely worth while to introduce any correction for the change of the initial volume by barometric variation. Or the instrument might be made with the re- curved bulb sealed, as in Professor Leslie's dif- ferential thermometers. The glass tube may be joined by fusion to the platinum tube. Care must be taken to let no mercury enter the platinum bulb. Should there be a mechanical difficulty in making a bulb of this metal, then a hollow cylinder of inch diameter, with PYR 675 PYR a platinum stem, like that of a tobacco- pipe, screwed into it, will suit equally well. PYROPHORUS. By this name is de- noted an artificial product, which takes fire or becomes ignited on exposure to the air. Hence, in the German language, it has obtained the name of luft-zunder, or air-tinder. It is pre- pared from alum by calcination, with the addi- tion of various inflammable substances. Hom- berg was the first that obtained it, which he did accidentally in the year 1680, from a mixture of human excrement and alum, upon which he was operating by fire. The preparation is managed in the fol- lowing manner. Three parts of alum are mixed with two -parts of honey or one of flour, or sugar ; and this mixture is dried over the fire in a glazed bowl, or an iron pan, diligently stirring it all the while with an iron spatula. At first this mixture melts, but by degrees it becomes thicker, swells up, and at last runs into small dry lumps. These are triturated to powder, and once more roasted over the fire, till there is not the least moisture remaining in them, and the operator is well assured that it can liquefy no more: the mass now looks like a blackish powder of charcoal. For the sake of avoiding the previous above-men- tioned operation, from four to five parts of burned alum may be mixed directly with two of charcoal powder. This powder is poured into a phial or matrass, with a neck about six inches long. The phial, which however must be filled three-quar- ters full only, is then put into a crucible, the bottom of which is covered with sand, and so much sand is put round the former that the upper part of its body also is co- vered with it to the height of an inch : upon this the crucible, with the phial, is put into the furnace, and surrounded with red-hot coals. The fire, being now gradually in- creased till the phial becomes red hot, is kept up for the space of about a quarter of an hour, or till a black smoke ceases to issue from the mouth of the phial, and instead of this a sulphureous vapour exhales, which commonly takes fire. The fire is kept up till the blue sulphureous flame is no longer to be seen ; upon this the calcination must be put an end to, and the phial closed for a short time with a stopper of clay or loam. But as soon as the vessel is become so cool as to be capable of being held in the hand the phial is taken out of the sand, and the powder contained in it transferred as fast as possible from the phial, into a dry and stout glass made warm, which must be secured with a glass stopper. We have made a very good pyrophorus by simply mixing three parts of alum with one of wheat-flour, calcining them in a common phial till the blue flame disappeared : and have kept it in the same phial, well stopped with a good cork, when cold. If this powder be exposed to the atmo- sphere, the sulphuret attracts moisture from the air, and generates sufficient heat to kindle the carbonaceous matter mingled with it. Dr. Gobel states, that when tartrate of lead is heated in a glass tube, a very perfect and beautiful pyrophorus is produced. When some of the dark brown mass thus formed is shaken out into the air, it immediately in- flames, and brilliant globules of lead cover the ignited surface ; some of these changing by degrees into litharge, offer a curious ap- pearance. The ignition continues much longer than with other pyrophori, which circumstance, with the facility of preparation, may make this a convenient method of obtaining fire. The inflammation of those substances, Dr. Gobel remarks, has been attributed principally to the presence of potassium ; but this new body affords a proof, that other metallic com- pounds are susceptible of spontaneous inflam- mation, on the accession of air. Dr. Hare prepares pyrophorus, by heating for an hour to a bright cherry-red, in an iron tube, a mixture of 3 parts lamp black, 4 calcined alum, and 8 pearl ashes. When well made, and poured out upon a glass plate (especially if breathed upon), it kindles with a series of small explosions, somewhat like those produced by throwing potassium upon water. There is even danger to die face, from the number and rapidity of these explosions. A ramrod, on being thrust down into a tube containing this pyrophorus, was projected with much violence, and several jets of fire. Suit- man's Journal, x. 366. PYROPE. A sub-species of dodecahedral garnet. Colour dark blood-red, appearing yellowish by transmitted light. In grains. Splendent. Fracture conchoidal. Transparent Refracts double. Scratches quartz more rea- dily than precious garnet. Sp. gr. 3-718. Its constituents are, silica 40, alumina 28-5, magnesia 10, lime 3-5, oxide of iron 16-5, of manganese 0-25, oxide of chrome 2, loss 1-25 Klaproth. It occurs in trap-tuff, at Ely, in Fifeshire ; and in claystone in Cum- berland. At Zeblitz, Saxony, it is imbedded in serpentine. It is highly valued as a gem in jewellery. PYROPHYSALITE. SeePnYSALiTE. PYROSMALITE. Colour liver-brown, inclining to pistachio-green. In lamellar concretions, and in regular six-sided prisms, or the same truncated. Shining. Fracture uneven. Translucent. Semi-hard. Streak brownish-white. Brittle. Sp. gr. 3.08. It is insoluble in water, but soluble in muriatic acid with a small residuum of silica. It gives out vapours of chlorine before the blowpipe, and becomes a magnetic oxide of iron. Its constituents are, peroxide of iron 21-81, prot- x x2 QUA 676 QUA oxide of manganese 21-14, sub-muriate of iron 14-09, silica 35-85, lime 1-21, water and loss 5-9. Hisinger* It occurs in a bed of magnetic ironstone, along with calcareous spar and hornblende, in Bjelke's mine in Nord- mark, near Philipstadt in Wermeland. It is a very singular compound. PYROTARTARIC ACID. See ACID (PYROTARTARTC). PYROXENE. Augite. PYROXILIC SPIRIT. Mr. Taylor describes in the GOth volume of the Philoso- phical Magazine, p. 315, a liquid which he obtained from the distillation of wood, which he called Pyroligneous Ether. This substance has been since examined by MM. Macaire and Marcet of Geneva, who have called it Pyrox- ilic spirit. It is transparent, colourless, of a strong etherous odour slightly resembling that of ants. Its taste is hot and strong, leaving a flavour of essence of mint. Its sp. gravity is 0-823. Boiling point about 150 F. Its slightly acid properties are due to a little acetic acid. It burns away entirely with a perfectly blue flame. Alcohol dissolves it, in all pro- portions, but water separates it again. It forms merely an emulsion with water. It does not combine with oil of turpentine. It dissolves camphor ; but not olive oil. It also dissolves pure potash. A kind of ether may be formed by the action of nitric acid and chlorine on it ; which shows its analogy to alcohol. The pyroacetic spirit of Chenevix, see SPIRIT (PYROACETIC), differs from this liquid in having a lower specific gravity =. 0-786 ; in taste and smell ; in burning with a white flame ; and in being quite soluble in oil of turpentine. Pyroxilic spirit consists, in 100 parts, of Carbon, 44-53 = 6 atoms. Oxygen, 46-61 =4 Hydrogen, M6 = 7 Pyroacetic spirit of Chenevix consists of Carbon, 55-30 = 4 atoms. Oxygen, 36-50 = 2 Hydrogen, 8-20 = 3 Alcohol sp. g. 0-820, consists, in 100, of Carbon, 48-8 =3 atoms. Oxygen, 39-9 = 2 Hydrogen, 11-3 = 5 There is some mistake in printing the atomic numbers. Bibliothequc Universclle^ and Journal of Science, xvii. 171. Q QUACK MEDICINES. The following formulae for the preparation of certain quack medicines have been published by Dr. Paris in his valuable Pharmacologia. Anderson's Pills. Aloes, jalap, oil of ani- seed. Aromatic Lozenges of Steel. Sulphate of iron and tincture of cantharides ! Pectoral Balsam of Honey. Tincture of benzoin. Barclay's Antibilious Pills. Extract of colocynth, 2 drachms ; extract of jalap, 1 drachm ; almond soap, 1 drachm and a half ; guaiacum, 3 drachms; tartarized antimony, 8 grains ; essential oils of juniper, caraway, and rosemary, of each 4 drops, formed into a mass with syrup of buckthorn, and divided into 64 pills. Bates' s Anodyne Balsam. 1 part of tinc- ture of opium, 2 parts of opodeldoc. Black Drop. Take half a pound of opium sliced, three pints of good verjuice, 1 ounce and a half of nutmegs, and half an ounce of saffron ; boil them to a proper thickness, then add a quarter of a pound of sugar, and two spoonfuls of yeast ; set the whole in a warm place near the fire for six or eight weeks, then place it in the open air until it becomes a syrup ; lastly, decant, filter, and bottle it up. One drop is considered equal to three of the tincture of opium pf the pharmacopoeia. Brodnm's Nervous Cordial consists of the tinctures of gentian, columba, cardamom, and bark, with the compound spirit of lavender and wine of iron. Chelsea Pensioner, a cure for rheumatism. Powdered guaiacum, 1 drachm ; rhubarb, 2 drachms ; cream of tartar, I ounce ; flowers of sulphur, 2 ounces ; 1 nutmeg finely powdered ; make into an electuary, with one pound of clarified honey ; two large spoonfuls to be taken night and morning. Ching's Worm Lozenges. Chiefly calomel and jalap. Coney's Depilatory. Quicklime and sul- phuret of potass. (We suspect orpiment in this compound). Duffy >s Elixir. Compound tincture of senna of the Edinburgh Pharmacopoeia, sweetened with treacle, and flavoured with aniseed and elecampane root. Dicey's Daffy and Swinton's Daffy differ little from each other. Daily's Carminative. Magnesia, 40 gr. ; oil of peppermint, 1 drop ; of nutmeg, 2 drops ; of aniseed, 3 drops ; tincture of cas- tor, 30 drops; of assafetida, 15 drops; of opium, 5 drops; spirit of pennyroyal, 15 drops ; compound tincture of cardamoms, 30 drops; peppermint- water, 2 ounces. Essence of Coltsfoot. This preparation (says Dr. Paris) consists of equal parts of the QUA 677 QUI balsam of Tolu and the compound tincture of benzoin, to which is added double the quantity of rectified spirit of wine ; and this, forsooth, is a pectoral for coughs ! If a patient, with a pulmonary affection, should recover during the use of such a mnedy, I should certainly designate it as a lucky escape, rather than a skilful cure. Whitehcad's Essence of Mustard. Oil of turpentine, camphor, and spirit of rosemary, with a little flour of mustard to colour it. Freeman's Bathing Spirits. Opodeldoc, coloured with Daffy's Elixir. Godbold's Vegetable Balsam. Honey and vinegar. Gotland's Lotion. A solution of corrosive sublimate, in emulsion of bitter almonds. James's Analcptlc Pills James's powder, gum ammoniacum, pill of aloes, with myrrh, of each equal parts, made into a mass with tincture of castor. Norrls's Drops. A coloured solution of tartarized antimony in rectified spirit. Remedies for the Hooping-coiigh. Either opiates, or medicines containing sulphate of zinc. Roche's Emlrocationfor the Hooping-cough. Olive oil, mixed with half its quantity of the oils of cloves and amber. Ruspini's Tincture for the Teeth. Floren- tine iris root, 8 ounces ; cloves, 1 ounce ; rec- tified spirit, 2 pints ; ambergris, 1 scruple. Scouring Drops. Oil of turpentine, per- fumed with essential oil of lemon-peel. Solomon's Balm of Gilead An aromatic tincture, of which cardamoms form the leading ingredient, made with brandy. Some prac- titioners have asserted that cantharides enter its composition. Steer's Opodeldoc. Castile soap, 1 ounce ; rectified spirit, 8 ounces ; camphor, 3 ounces and a half; oil of rosemary, half a drachm ; oil of origanum, 1 drachm ; solution of am- monia, G drachms. Taylor's Remedy for Deafness. Garlic, infused in oil of almonds, and coloured by alcanet root. QUARTATION is an operation by which the quantity of one thing is made equal to a fourth part of the quantity of another thing. Thus, when gold alloyed with silver is to be parted, we are obliged to facilitate the action of the aquafortis by reducing the quantity of the former of these metals to one- fourth part cf the whole mass ; which is done by sufficiently increasing the quantity of the silver, if it be necessary. This operation is called quartation, and is preparatory to the parting ; and even many authors extend this name to the opera- tion of parting. See ASSAY. QUARTZ. Professor Jameson divides this mineral genus into two species ; rhomboidal quarts, and indivisible quartz. L Rhomlnridal quartz contains 14 sub- species. 1. Amethyst. 2. Hock crystal. 3. Milk quartz. 4. Common quartz. 5. Prase. 6 % . Cat's eye. 7- Fibrous quartz. 8. Iron flint. 9. Hornstone. 10. Flinty slate. 11. Flint. 12. Calcedony. 13. Heliotrope. 14. Jasper. 2. Indivisible quartz contains nine sub- species. 1. Float-stone. 2. Quartz sinter. 3. Hyalite. 4. Opal. 5. Menilite. 6. Obsidian. 7. Pitchstone. 8. Pearlstone. 9. Pumice-stone. We shall treat here of the quartz sub-species. 1. Rose or milk quartz. Colour rose-red, and milk-white. Massive. Shining. Frac- ture conchoidal. Translucent. It is probably < silica, coloured with manganese. It is found in Bavaria, where it occurs in beds of quartz in granite, near Zwiesel, &c. 2. Common quartz. Colours white, gray, and many others. Massive, disseminated, imitative, in impressed forms, in supposititious and true crystals. The latter are, a six-sided prism, acuminated on both extremities by six planes; a simple six-sided pyramid, and a double six-sided pyramid. Splendent to glis- tening. Fracture coarse splintery, and some- times slaty. Translucent. It is one of the most abundant minerals in nature. 3. Fibrous quartz. Colours greenish and yellowish white. Massive, and in rolled pieces. In curved fibrous concretions. Glimmering and pearly. Fracture curved slaty. Translucent on the edges. Nearly as hard as quartz. Not very difficultly frangible. Sp.gr. 3-123? It occurs on the banks of the Moldare in Bohemia. 4. Quartz, or siliceous sinter^ Of this there are three kinds ; the common, opaline, and pearly. 1. Common. Colours grayish-white and reddish- white. Massive and imitative. Dull. Fracture flat conchoidal. Translucent on the edges. Semi-hard. Very bri ttle. Sp. gr. 1-81. Its constituents are, silica 98, alumina 1-5, iron 0-5 Klapr. It occurs abundantly round the hot springs in Iceland. 2. Opaline siliceous sinter. Colour yel- lowish white. Massive. Fracture conchoidal. Glimmering. Translucent on the edges. Se- mi-hard. Brittle. Adheres to the tongue. It occurs at the hot springs in Iceland. It resem- bles opal. 3. Pearl sinter, orjiorite. Colour milk- white. In imitative shapes. Lustre between resinous and pearly. In thin concentric lamel- lar concretions. Fracture fine grained uneven. Translucent. Scratches glass, but not so hard as quartz. Brittle. Sp. gr. 1-917- Its con- stituents are, silica 94, alumina 2, lime 4. Santi. It has been found in volcanic tuff and pumice, in the Vicentine. See ROCK CRYSTAL. QUERCITRON. See DYEING. QUICKSILAHER. See MEIICURY. QUININA or QUINIA. . A vegetable alkali, extracted from pale cinchona, by a RA1 678 RAI process exactly similar to that described under Cinchonina. It is obtained in transparent plates. It is as insoluble in water as cincho- nina ; but its taste is more bitter. It unites with the acids, forming crystallizable salts. The sulphate is of a dull white colour, silky and flexible : it is, like the alkali, soluble in alcohol; it burns away without leaving any residuum. According to MM. Pelletier and Caventou, it is composed of Quinina, 100 Sulphuric acid, 10-9147 but M. Baup describes a crystallized sulphate as well as a supersulphate. The first consists of Quinina, 1 prime, 45 Sulphuric acid, 1 5 Water, 4 4-5 The second, of Quinina, Acid, Water, 54-5 1 prime, 45 2 10 16 18 73 The acetate is remarkable for the manner in which it crystallizes. Its crystals are flat needles of a pearly appearance, which are grouped in silky bundles, or in stars. Neutral sulphate. 1 atom Quinia, 45 76-272 2 Sulph. acid, 5 8-474 8 Water, 9 15-254 100-000 Quinina is very soluble in ether ; cinchonina is not. Hence this liquid may be employed to separate these two alkalis. The sulphate of quinina, in doses of from 6 to 12 grains, has been found an effectual remedy against intermittent fevers. It is said that the red or yellow bark yields the most febrifuge quiniua. See Journal of Science, x. 391, and xii. 327- Quinina agrees with cinchonina, in affording a large quantity of ammonia, when subjected to destructive distillation, and consequently in containing azote as one of its elements. Ana- lyzed by Mr. Brande, it afforded, in 100 parts, Carbon, 73-80 Azote, 13-00 Hydrogen, 7-65 Oxygen, 5-55 100-00 Journ. of Science, xvi. 283. Analysis by Dumas and Pelletier, Carbon, 74-14 Hydrogen, 6-77 Azote, 8-80 Oxygen, 10-76 Ann. de Chim. xxiv. 176. M. Baup adopts 45 as the prime equi- valent of quinia. He states its sulphates as follows : Supersulphate in rectangular prisms. 1 atom 45 61-644 2 Ifi 10 18 13-698 24-658 100-000 Ann. de Chimie, xxvii. 323. R RADICAL. That which is considered as constituting the distinguishing part of an acid, by its union with the acidifying principle, or oxygen, which is common to all acids. Thus, sulphur is the radical of the sulphuric and sulphurous acids. It is sometimes called the base of the acid, but base is a term of more extensive application. RADICAL VINEGAR. See ACID (ACETIC). RAIN. Mr. Luke Howard, who may be considered as one of our most accurate scientific meteorologists, is inclined to think, that rain is in almost every instance the result of the electrical action of clouds upon each other. This idea is confirmed by observations made in various ways, upon the electrical state of clouds and rain ; and it is very probable that a thunder-storm is only a more sudden and sensible display of those energies, which, according to the order observable in the crea- tion in other respects, ought to be incessantly and silently operating for more general and beneficial purposes. In the formation of the rain cloud (nimlus\ two circumstances claim particular attention ; the spreading of the superior masses of cloud, in all directions, until they become like the ttratus 9 one uniform sheet ; and the rapid motion, and visible decrease, of the cumulus when brought under the latter. The cirri also, which so frequently stretch from the superior sheet upwards, and resemble erected hairs, carry much the appearance of tempo- rary conductors for the electricity, extricated by the sudden union of minute particles of vapour, into the vastly larger ones that form the rain. By one experiment of Cavallo's, with a kite carrying 360 feet of conducting string, in an interval between two showers, and kept up during rain, it seems that the superior clouds possessed a positive electricity before the rain, which on the arrival of a large cumulus, gave place to a very strong negative, RAI 679 RAI continuing as long as it was over the kite. We are not, however, warranted from this to conclude the cumulus which brings on rain always negative, as the same effect might ensue from a positive cumulus uniting with a nega- tive stratus. Yet the general negative state of the lower atmosphere during rain, and the positive indications commonly given by the true stratus, render this the more probable opinion. It is not, however, absolutely neces- sary to determine the several states of the clouds which appear during rain, since there is sufficient evidence in favour of the conclu- sion, that clouds formed in different parts of the atmosphere, operate on each other, when brought near enough, so as to occasion their partial or entire destruction ; an effect which can be attributed only to their possessing before-hand, or acquiring at the moment, the opposite electricities. It may be objected, says Mr. Howard, that this explanation is better suited to the case of a shower than to that of continued rain, for which it does not seem sufficient If it should appear, nevertheless, that the supply of each kind of cloud is by any means kept up in proportion to the consumption, the ob- jection will be answered. Now, it is a well known fact, that evaporation from the surface of the earth and waters, often returns and continues during rain, and consequently fur- nishes the lower clouds, while the upper are recruited from the quantity of vapour brought by the superior current, and continually sub- siding in the form of dew, as is evident both from the turbidness of the atmosphere in rainy seasons, and the plentiful deposition of dew in the nocturnal intervals of rain. Neither is it pretended that electricity is any further con- cerned in the production of rain, than as a secondary agent, which modifies the effect of the two grand predisposing causes, a falling temperature, and the influx of vapour. Mr. Dalton, who has paid much attention to meteorology, has recently read before the Manchester Society, an elaborate and interest- ing memoir on rain, from which I shall ex- tract a table, and some observations. Mean Monthly and Annual Quantities of Rain at Various Places, Icing the Averages for many Years, by MR. DALTON. O yj (I Is Eg fi- ll li 3 g >. li II .2 c3 if. li i li M .:; * Is * G * 5 P-I m > 1 P o Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. Fr. In. Fr. In. Inch. Jan. 2-310 2-177 2-196 3-461 5-299 3.095 1-595 1-464 1-228 2-477 2-530 Feb. 2-568 1-847 1-652 2-995 5-126 2-837 1-741 1-250 232 1-700 2-295 Mar. 2-098 1-523 1-322 1-753 3-151 2-164 1-184 1-172 190 1-927 1-748 April 2-010 2-104 2-078 2-180 2-986 2-017 0-979 1-279 -185 2-686 1-950 May June 2-895 2-502 2-573 2-816 2-118 2-286 2-460 2-512 3-480 2-722 2-568 2-974 1-641 1-343 1-636 1-738 767 697 2-931 2-562 2407 2-315 July Aug. 3-697 3-665 3-663 3311 3-006 2-435 4-140 4-581 4-959 5-039 3-256 3-199 2-303 2-746 2-448 1-807 800 900 1-882 2-347 3-115 3-103 Sept. Oct. Nov. 3-281 3-922 3-360 3-654 3724 3-441 2-289 3079 2-634 3-751 4-151 3.775 4-874 5-439 4-785 4-350 4-143 3-174 1-617 2-297 1-904 1-842 2.092 2-222 -550 1-780 1-720 4-140 4-741 4-187 3-135 3-537 3-120 Dec. 3-832 3-288 2-569 3-955 6-084 3-142 1-981 1-736 1-600 2-397 3-058 36-140 34-118 27-664 39-714 53-944 36-919 21-331 20-686 18-649 33-977 " Observations on the Theory of Rain. " Every one must have noticed an obvious connexion between heat and the vapour in the atmosphere. Heat promotes evaporation, and contributes to retain the vapour when in the atmosphere, and cold precipitates or condenses the vapour. But these facts do not explain the phenomenon of rain, which is as frequently attended with an increase as with a diminution of the temperature of the atmosphere. " The late Dr. Hutton, of Edinburgh, was, I conceive, the first person who published a correct notion of the cause of rain. (See Edin. Trans, vol. L and ii. and Button's Dis- sertations, &c.) Without deciding whether vapour be simply expanded by heat, and dif- fused through the atmosphere, or chemically combined with it, he maintained from the phe- nomena that the quantity of vapour capable of entering into the air increases in a greater ratio than the temperature; and hence he fairly infers, that whenever two volumes of air of different temperatures are mixed together, each being previously saturated with vapour, REA 680 RES a precipitation of a portion of vapour must ensue, in consequence of the mean temperature not being able to support the mean quantity of vapour. " The cause of rain, therefore, is now, I consider, no longer an object of doubt. If two masses of air, of unequal temperatures, by the ordinary currents of the winds are intermixed, when saturated with vapour, a precipitation ensues. If the masses are under saturation, then less precipitation takes place, or none at all, according to the degree. Also the warmer the air, the greater is the quantity of vapour precipitated in like circumstances. Hence the reason why rains are heavier in summer than winter, and in warm countries than in cold. " We now inquire into the cause why less rain falls hi the first six months of the year than in the last six months. The whole quantity of water in the atmosphere in Janu- ary is usually about three inches, as appears from the dew point, which is then about 32. Now the force of vapour at that temperature is 0-2 of an inch of mercury, which is equal to 2.8 or three inches of water. The dew point in July is usually about 58 or 59, corresponding to 0-5 of an inch of mercury, which is equal to seven inches of water ; the difference is four inches of water, which the atmosphere then contains more than in the former month. Hence, supposing the usual intermixture of currents of air in both the intervening periods to be the same, the rain ought to be four inches less in the former period of the year than the average, and four inches more in the latter period, making a difference of eight inches between the two periods, which nearly accords with the pre- ceding observations." Mr. Daniell's Meteo- rological Essays contain the best body of in- formation on the phenomena of rain, dew, and climate, which is extant. .RANCIDITY. The change which oils undergo by exposure to the air. The rancidity of oils is probably an effect analogous to the oxidation of metals. It es- sentially depends on the combination of oxygen with the extractive principle, which is na- turally united with the oily principle. This inference is proved by attending to the pro- cesses used to counteract or prevent the ran- cidity of oils. REAGENT. In the experiments of che- mical analysis, the component parts of bodies may either be ascertained in quantity as well as quality, by the perfect operations of the laboratory, or their quality alone may be de- tected by the operations of certain bodies called reagents. Thus the infusion of galls is a reagent, which detects iron by a dark purple precipitate ; the prussiate of potash exhibits a blue with the same metal, &c. See ANALYSIS, and WATEIIS (MINERAL). REALGAR. Sulphuret of arsenic, a native ore. RECEIVER. Receivers are chemical vessels, which are adapted to the necks or beaks of retorts, alembics, and other distilla- tory vessels, to collect, receive, and contain the products of distillations. RED CHALK. A kind of clay iron-stone. REDDLE. Red chalk. REDUCTION, OR REVIVIFICA- TION. This word, in its most extensive sense, is applicable to all operations by which any substance is restored to its natural state f or which is considered as such : but custom confines it to operations by which metals are restored to their metallic state, after they have been deprived of this, either by combustion, as the metallic oxides, or by the union of some heterogeneous matters which disguise them, as fulminating gold, luna cornea, cin- nabar, and other compounds of the same kind. These reductions are also called revivifications. REFRIGERATORY. See LABORA- TORY, REGULUS. The name regulus was given by chemists to metallic matters when separated from other substances by fusion. This name was introduced by alchemists, who, expecting always to find gold in the metal collected at the bottom of their crucibles after fusion, called this metal, thus collected, regulus, as containing gold, the king of metals. It was afterwards applied to the metal extracted from the ores of the semi-metals, which formerly bore the name that is now given to the semi- metals themselves. Thus we had regulus of antimony, regulus of arsenic, and regulus of cobalt^ RESIN. The name resin is used to denote solid inflammable substances, of vegetable origin, soluble in alcohol, usually affording much soot by their combustion. They are likewise soluble in oils, but not at all in water ; and are more or less acted upon by the alkalis. All the resins appear to be nothing else but volatile oils, rendered concrete by their combination with oxygen. The exposure of these to the open air, and the decomposition of acids applied to them, evidently prove this conclusion. There are some among the known resins which are very pure, and perfectly soluble in alcohol, such as the balsam of Mecca and of capivi, turpentines, tacamabaca, elemi ; others are less pure, and contain a small portion of extract, which renders them not totally soluble in alcohol ; such are mastic, sandarach, guai- acurn, labdanum, and dragon's blood. What is most generally known by the name of resin simply, or sometimes of yellow resin, is the residuum left after distilling the essential oil from turpentine. If this be urged by a stronger fire, a thick balsam, of a dark-red- dish-colour, called balsam of turpentine, comes over; and the residuum, which is rendered blackish, is called black resin, or colophony. Resin, analyzed by MM. Gay Lussac and Thenarcl, was found to consist of RET 681 HHO Carbon, 75-944 Hydrogen, 10-7191 water 19-156 Oxygen, 13-337 J hydrogen in excess 8.9- By my analysis resin consists, in 100 parts, of Carbon, 73.G Hydrogen, 12-9 Oxygen, 13-5 Phil Trans. 1822. RESPIRATION. A function of animals, which consists in the alternate inhalation of a portion of air into an organ called the lungs, and its subsequent exhalation. The venous blood, which enters the lungs from the pul- monary artery, is charged with carbon, to which it owes its dark purple colour. When the atmospherical oxygen is applied to the interior of the air-vesicles of the lungs, it combines with the carbon of the blood, forms carbonic acid, which to the amount of from 4-5 to 8 per cent, of the bulk of air inspired is immediately exhaled. It does not appea~ that any oxygen or azote is absorbed by the lungs in respiration, for the volume of car- bonic acid generated is exactly equal to that of the oxygen which disappears. Now, we know that carbonic acid contains its own volume of oxygen. It is probable that the quantity of carbonic acid, produced in the lungs, varies in different individuals, and in the same individual under different circum- stances. The change of the blood, from the purple venous to the bright red arterial, seems owing to the discharge of the carbon. An ordinary sized man consumes about 46,000 cubic inches of oxygen per diem; equi- valent to 125 cubic feet of air. He makes about 20 respirations in a minute ; or breathes twice, for every seven pulsations. Dr. Prout and Dr. Fyfe found, that after swallowing intoxicating liquors, the quantity of carbonic acid formed in respiration was diminished. The same thing happens under a course of mercury, nitric acid, or vegetable diet. RETINITE. Retin-asphalt. Hatcliett. Colour yellowish and reddish -brown. Massive, in angular pieces and thick crusts. Surface rough. Glistening, resinous. Fracture uneven. Translucent. Soft. Brittle. At first elastic, but becomes rigid by exposure to the air. Sp. gr. 1-135. On a hot iron, it melts, smokes, and burns, with a fragrant odour ; soluble in potash, and partially in spirit of wine. Its constituents are, resin 55, asphalt 42, earth 3. It is found at Bovey Tracy in Devonshire, adhering to brown coal. RETORT. Retorts are vessels employed for many distillations, and most frequently for those which require a degree of heat superior to that of boiling water. This vessel is a kind of bottle with a long neck, so bent, that it makes with the belly of the retort an angle of about sixty degrees. From this form they have probably been named retorts. The most capacious part of the retort is called its belly. Its upper part is called the arch or roof of the retort, and the bent part is the neck. REUSSITE. Colour white. As a meal/ efflorescence, and crystallized, in flat six-sided prisms and acicular crystals. Shining. Frac- ture conchoidal. Soft. Its constituents are, sulphate of soda 66-04, sulphate of magnesia 31-35, muriate of magnesia 2-19, and sulphate of lime 0-42. Reuss. It is found as an ef- florescence on the surface, in the country round Sedlitz and Seidschutz. REVERBERATORY. See LABORA- TORY. RHABARBARINE. The name of a supposed alkaline base in rhubarb, described by M. Nani of Milan. Billioth. Univers. xxii. 232, and Journal of Science, xvi. 172. RHODIUM. A new metal discovered among the grains of crude platina by Dr. Wollaston. The mode of obtaining it in the state of a triple salt combined with muriatic acid and soda has been given under the article PALLADIUM. This may be dissolved in water and the metal precipitated from it in a black powder by zinc. This powder exposed to heat continues black ; but with borax it acquires a white metallic lustre, though it remains infusible. Sulphur, or arsenic, however, renders it fusible, and may afterward be expelled by continuing the heat. The button however is not mal- leable. Its specific gravity appears not to exceed 11. Rhodium unites easily with every metal that has been tried, except mercury. With gold or silver it forms a very malleable alloy, not oxidated by a high degree of heat, but becoming incrusted with a black oxide when slowly cooled. One-sixth of it does not per- ceptibly alter the colour of gold, but renders it much less fusible. Neither nitric nor nitro- muriatic acid acts on it in either of these alloys ; but if it be fused with three parts of bismuth, lead, or copper, the alloy is entirely soluble in a mixture of nitric acid with two parts of muriatic. The oxide was soluble in every acid Dr. Wollaston tried. The solution in muriatic acid did not crystallize by evaporation. Its residuum formed a rose-coloured solution with alcohol. Muriate of ammonia and of soda, and nitrate of potash, occasioned no precipitate in the muriatic solution, but formed with the oxide triple salts, which were insoluble in al- cohol. Its solution in nitric acid likewise did not crystallize ; but silver, copper, and other metals precipitated it. The solution of the triple salt with muriate of soda was not precipitated by muriate, car- bonate, or hydrosulphuret of ammonia, by carbonate or ferroprussiate of potash, or by carbonate of soda. The caustic alkalis how- ever throw down a yellow oxide, soluble in excess of alkali; and a solution of platina occasions in it a yellow precipitate. The title of this product to be considered as a distinct metal was at first ques'ioned ; but ROC 682 ROS the experiments of Dr. Wollaston have since been confirmed by Descotils. Phil. Trans. RHODONITE. A fibrous ore of manga- nese, containing silica 39, protoxide of man- ganese 50, &c. RHCETIZITE. Colour white. Massive, and in radiated concretions. Glistening and pearly. Fragments splintery. Feebly trans- lucent on the edges. In other characters, the same as cyanite. It occurs in primitive rocks, with quartz, &c. at Pfitzsci in the Tyrol. RHOMB SPAR. Colour grayish-white. Massive, disseminated, and crystallized in rhomboids, in which the obtuse angle is 106 15'. Splendent, between vitreous and pearly. Cleavage threefold oblique angular. Fracture imperfect conchoidal. Harder than calcareous spar; sometimes as hard as fluor. Brittle. Sp. gr. 2-8 to 3-2. It effervesces feebly with acids. Its constituents are, carbonate of lime 56-6, carbonate of magnesia 42, with a trace of iron and manganese. Murray. It occurs imbedded in chlorite slate, limestone, &c. It is found on the banks of Loch Lomond ; near Newton-Stewart in Galloway ; in compact dolomite in the Isle of Man and the North of England. It has been called bitter spar and muricalcite. RHUBARB (ROOT OF). Mr. Brande gives the following analysis of this medicine : Water, 8-2 Gum, 31-0 Resin, 10-0 Extract, tan and gallic acid, 26-0 Phosphate of lime, 2-0 Malate of lime, 6' 5 Woody fibre, 16-3 100-0 ROCHE LLE SALT. Tartrate of potash and soda. See ACID (TAB.TARIC). ROCK BUTTER. Colour yellowish- white. Massive and tuberose. Glimmering. Fracture straight foliated. Translucent on the edges. Feels rather greasy. Easily frangible. It is alum mixed with alumina and oxide of iron. It oozes out of rocks that contain alum. It occurs at the Hurlett alum-work, near Paisley. ROCK CORK. See ASBESTUS. ROCK CRYSTAL. Colour white and brown. In rolled pieces, and crystallized. The primitive form is a rhomboid of 94 15' and 85 45'. The secondary forms are, an equi- angular six-sided prism, rather acutely acu- minated on both extremities by six planes, which are set on the lateral planes ; a double six-sided pyramid ; an acute simple six-sided pyramid ; an acute double three-sided pyramid. Splendent. Fracture perfect conchoidal. Trans- parent or translucent. Refracts double, feebly. Scratches felspar. Rather easily frangible. Sp. gr. 2-6 to 2-88. When two pieces are rubbed against each other, they become phosphorescent, and exhale an electric odour. Its constituents are, silica 89f, and a trace of ferruginous alu- Tnimi.-Biic7iolz. Some chemists maintain, that it has one or two per cent, of moisture. Crystals of great size and beauty are found in Arran, in drusy cavities in granite ; but the finest are found in the neighbourhood of Cairngorm in Aberdeenshire, where they occur in granite, or in alluvial soil, along with beryl and topaz ; and in the secondary greenstone of Burntisland in Fifeshire. The most magnificent groups of crystals come from Dauphiny. The varieties enclosing crystals of titanium, the Venus hair-stones of amateurs, and those containing actinclite, or the Thetis hair-stones, are in much repute, and sell at a considerable price. Jameson. ROCK SALT. Hexahedral rock salt. 1. Foliated. Colours white and gray. Mas- sive, disseminated, and crystallized in cubes. '^Splendent and resinous. Cleavage threefold rectangular. Fracture conchoidal. Fragments cubic. Translucent. As hard as gypsum. Feels rather greasy. Brittle. It has a saline taste. Sp. gr. 2-1 to 2.2. 2. Fibrous. Colour white. Massive, and in fibrous concretions. Glistening, resinous. Fragments splintery. Translucent. It de- crepitates when heated. The constituents of Cheshire rock salt, in 1000 parts, are, muriate of soda 983|, sulphate of lime 6, muriate of magnesia O.y^-, muriate of lime^O.-j 3 ^, in- soluble matter 10. Henry. The greatest formation of rock salt is in the muriatiferous clay. The salt is occasion- ally associated with thin layers of anhydrite, stinkstone, limestone, and sandstone. The principal deposit in Great Britain is in Cheshire. The beds alternate with clay and marie, which contains gypsum. It occurs also at Droit- wich in Worcestershire. For other localities see Professor Jameson's Mineralogy, iii. 6. ROCK WOOD. See ASBESTUS. ROMANZOVITE. A new mineral found in the lime quarry of Kulla, at Kimito, in Finland. Its colours are brown, brownish- yellow, and blackish-brown. Compact, or in crystalline planes, inclined at an angle of 120 to each other. Fracture small conchoidal like common rosin. Lustre shining, between vi- treous and resinous. Translucent, in thin fragments. Hard, giving sparks with steel. Brittle. Scratches glass and felspar ; but is scratched by quartz. Sp. gr. 3-6. In powder, light yellow. Melts in the interior flame of the blowpipe. Constituents, Silica 41-24 Lime * ; 24-76 Alumina 24-08 Oxide of iron 7-02 Magnesia and oxide of manganese 0-1)2 Volatile parts and loss 1-98 M. Jul'm. ROSESTONE. 100-00 Annals of Phil. i. 233. See LIMESTONE. SAL 683 SAL ROSE QUARTZ. See QUARTZ. ROSEL1TE. This new mineral occurs in small well-defined translucent crystals of a deep rose colour, on amorphous grayish quartz It comes from Schneeberg in Saxony. It has hitherto been placed with the arseniate of co- balt, from the same locality. It contains arsenic acid, united to oxide of cobalt, lime, and magnesia, elements which constitute the picropharmacolite of Stromeyer. See PHAR- MACOLITE. Annals of Phil. viii. 439. RUBE LITE. Red tourmalin. RUBY. See SAPPHIRE, RUBY-SPINEL. See SPINEL. RUST. Red carbonate of iron. RUTILE. An ore of titanium. SACLACTATES. See ACID (SAC- LACTIC). SAFFLOWER. See CARTHAMUS. SAGENITE. Acicular rutile. S AH LITE. Colours greenish-gray, and green of other shades. Massive, in straight lamellar concretions, and crystallized ; in a broad rectangular four-sided prism, approach- ing the tabular form, or truncated on the lateral edges. Splendent on the principal fracture ; on the cross fracture, dull. Cleavage fivefold. Fracture uneven. Translucent on the edges. Harder than augite. Rather brittle. Sp. gr. 3-22 to 3-47. It melts with great difficulty. Its constituents are, silica 53, magnesia 19, alumina 3, lime 20, iron and manganese 4. Vauquelin. It occurs in the Island of Unst in Shetland ; in granular limestone in the Island of Tiree ; and in Glentilt. It is a sub- species of oblique-edged augite. SAL ALEMBROTH. A compound mu- riate of mercury and ammonia. See ALEM- BROTH. SAL AMMONIAC (NATIVE); of which there are two kinds, the volcanic and conchoidal. 1 . Volcanic. Colour yellowish and grayish- white. In efflorescences, imitative shapes, and crystallized ; in an octahedron ; rectangular four-sided prism, acuminated with four planes, set on the lateral planes ; a cube truncated on the edges ; a rhomboidal dodecahedron, and a double eight- sided pyramid, acuminated with four planes. Shining. Cleavage in the di- rection of the planes of the octohedron. From transparent to opaque. Harder than talc. Ductile and elastic. Sp. gr. 1-5 to 1-6. Taste sharp and urinous. When rubbed with quick- lime, it exhales ammonia. Its constituents are, sal ammoniac 99-5, muriate of soda 0-5. Klaproth. It occurs in the vicinity of burning; beds of coal, both in Scotland and England. It is met with at Solfaterra, Vesu- vius, jEtna, &c. 2. Conchoidal. It occurs in angular pieces, and consists of, sal ammoniac 97'5? sulphate of ammonia 2-5 Klaproth. It is said to occur, along with sulphur, in beds of indu- rated clay or clay-slate, in the country of Bucharia. Jameson. See ACID (MURI- ATIC). SAL AMMONIAC. Muriate of am- monia. SAL AMMONIAC (SECRET). Sul- phate of ammonia, so called by its discoverer Glauber. SAL CATHARTICUS AMARUS. Sul- phate of magnesia. SAL DE DUOBUS. Sulphate of potash. SAL DIURETICUS. Acetate of potash. SAL GEM. Native muriate of soda. SAL GLAUBERI. Sulphate of soda. SAL MARTIS. Green sulphate of iron. SAL MIRABILE, OR SAL MIRA- BILE GLAUBERI. Sulphate of soda. SAL MIRABILE PERLATUM, OR SAL PERLATUM. Phosphate of soda. SAL POLYCHREST GLASERI. Sul- phate of potash. SAL PRUNELLA. Nitrate of potash, cast into flat cakes or round balls, after fusion. SALIFIABLE BASES, are the alkalis, and those earths and metallic oxides which have the power of neutralizing acidity entirely or in part, and producing salts. SALIVA. The fluid secreted in the mouth, which flows in considerable quantity during a repast, is known by die name of saliva. Saliva, beside water, which constitutes at least four-fifths of its bulk, contains the fol- lowing ingredients : 1. Mucilage, 2. Albumen, 3. Muriate of soda, 4. Phosphate of soda, 5. Phosphate of lime, 6. Phosphate of ammonia. But it cannot be doubted, that, like all the other animal fluids, it is liable to many changes from disease, &c. Brugnatelli found the saliva of a patient labouring under an obstinate ve- nereal disease impregnated with oxalic acid. The concretions which sometimes form in the salivary ducts, &c. and the tartar or bony crust which so often attaches itself to the teeth, are composed of phosphate of lime. SAL 684 SAL SALMI AC. A word sometimes used for sal ammoniac. SALT. This term has been usually em- ployed to denote a compound, in definite pro- portions, of acid matter, with an alkali, earth, or metallic oxide. When the proportions of the constituents are so adjusted, that the re- sulting substance does not affect the colour of infusion of litmus, or red cabbage, it is then called a neutral salt. When the predominance of acid is evinced by the reddening of these infusions, the salt is said to be acidulous, and the prefix, super, or bi. is used to indicate this excess of acid. If, on the contrary, the acid matter appears to be in defect, or short of the quantity necessary for neutralizing the alkalinity of the base, the salt is then said to be with excess of base, and the prefix sub is attached to its name. The discoveries of Sir H. Davy have how- ever taught us to modify our opinions con- cerning saline constitution. Many bodies, such as culinary salt, and muriate of lime, to which the appellation of salt cannot be refused, have not been proved to contain either acid or alka- line matter ; but must, according to the strict logic of chemistry, be regarded as compounds of chlorine with metals. That great chemist remarks, that very few of the substances which have been always con- sidered as neutral salts, really contain, in their dry state, the acids and alkalis from which they were formed. According to his views, the muriates and fluates must be admitted to contain neither acids nor alkaline bases. Most of the prussiates (or prussides) are shown by M. Gay Lussac to be in the same case. Nitric and sulphuric acids cannot be procured from the nitrates and sulphates, without the inter- vention of bodies containing hydrogen ; and if nitrate of ammonia were to be judged of from the results of its decomposition, it must be regarded as a compound of water and nitrous oxide. To this position it might per- haps be objected, that dry sulphate of iron yields sulphuric acid by ignition in* a retort, while oxide of iron remains. Only those acids, says he, which are compounds of oxygen and inflammable bases, appear to enter into com- bination with the fixed alkalis and alkaline earths without alteration, and it is impossible to define the nature of the arrangement of the elements in their neutral compounds. The phosphate and carbonate of lime have much less of the characters attributed to neutro-saline bodies than chloride of calcium (muriate of lime), and yet this last body is not known to contain either acid or alkaline matter. M. Gay Lussac supposes, that a chloric acid, without water or hydrogen, of one prime pro- portion of chlorine and five of oxygen, exists in all the hyperoxymuriates (chlorates), but he does not support his proposition by any proof. Tim hyperoxymuriates were shown by Sir H. Davy, in 1811, to b; composed of one prime of chlorine, one of a basis, and six of oxygen. Now hydrogen, in the liquid chloric acid of M. Gay Lussac, may be considered as acting the part of a base ; and to be exchanged for potassium in the salt hypothetically called chlorate of potash. It is an important circum- stance in the law of definite proportions, that when one metallic or inflammable basis (po- tassium or hydrogen, for example), combines with certain proportions of a compound as hyperoxygenated chlorine, all the others com- bine with the same proportions. M. Gay Lussac states, that if the chloric acid be not admitted as a pure combination of chlorine and oxygen, neither can the hydro- nitric or hydrosulphuric acids be admitted as pure combinations of oxygen. This is per- fectly obvious. An acid composed of five pro- portions of oxygen, and one of nitrogen, is altogether hypothetical ; and it is a simple statement of facts to say, that liquid nitric acid is a compound of one prime equivalent of hydrogen, one of azote, and six of oxygen (such acid has a sp. gr. considerably greater than 1-50). The only difference therefore between nitre and hyperoxymuriate of potash is, that one contains a prime of azote, and the other a prime of chlorine. Thus, Nitrate of potash. Chlorate of potash. 1 prime azote, 1 prime chlorine, 6 primes oxygen, 6 primes oxygen, J prime potassium. 1 prime potassium. In each, substitute hydrogen for its kindred combustible, potassium, and you have the liquid acids. The chloriodic acid, the chlorocarbonous, and the binary acids, containing hydrogen, as muriatic and hydriodic, combine with am- monia without decomposition, but they appear to be decomposed in acting upon the fixed alkalis, or alkaline earths ; and yet the solid substances they form have all the characters which were formerly regarded as peculiar to neutral salts, consisting of acids and alkalis, though none of them contain the acid, and only the two first of the series contain the alkalis from which they are formed. The preceding views of saline constitution seem to be perfectly clear and satisfactory ; and place in a conspicuous light the paramount logic of the English chemist The solubility of salts in water is their most important general habitude. In this menstruum they are usually crystallized ; and by its agency they are purified and separated from one another, in the inverse order of their solubility. The most extensive series of ex- periments on the solubility of salts, which has been published, is that of Hassenfratz, con- tained in the 27th, 28th, and 31st volumes of the Annalcs de Chimie. Dr. Thomson has copied them into the third volume of his Sys- SAL 685 SAL tern: and I should also have willingly fol- lowed the example, were I not aware, from my own researches, that several of Hassen- fratz's results are erroneous. It is ten years since I commenced a very extensive train of experiments on this subject, so important to the practical chemist, but unforeseen obstruc- tions have hitherto prevented their completion. Many of Hassenfratz's determinations, how- ever, are very nearly correct. But his state- ment of the relation between the density of slacked lime, and the proportion of its com- bined water, is so absurd, that I wonder that a person of his reputation should have pub- lished it, and that Dr. Thomson should have embodied it in his system. In one experi- ment, 10000 grains of lime, sp. gr. 1.5949, combined with 1620 of water, give a hydrate of sp. gr. 1.4877; and, in another, 10000 grains of lime, sp. gr. 1.3175, combined with 1875 of water, form a hydrate of sp. gr. 0.972. Four parts of lime sp. gr. 1.4558, combined with 1 of water, are stated to yield a hydrate of sp. gr. 1.400 ; and with 2 of water, of specific gravity 0.8983 ! Now, the last pro- portion forms a mass greatly denser than water, instead of being much lighter than proof spirits. "Mr. Kirwan has pointed out," says Dr. Thomson, "a very ingenious method of esti- mating the saline contents of a mineral water whose specific gravity is known ; so that the error does not exceed one or two parts in the hundred. The method is this : subtract the specific gravity of pure water from the specific gravity of the mineral water examined (both expressed in whole numbers), and multiply the remainder by 1-4. The product is the saline contents, in a quantity of the water, denoted by the number employed to indicate the specific gravity of distilled water. Thus, let the water be of the specific gravity 1.079, or in whole numbers 1079. Then the spe- cific gravity of distilled water will be 100. And 1079 1000 + 1-4 = 110.6 = saline contents in 1000 parts of the water in question ; and, consequently, 11.06 (erroneously printed 110.6) in 100 parts of the same water." Divested of its superfluous tautology, this rule is : Multiply by 140 the decimal part of the number, representing the sp. gr. of the saline solution, and the product is the dry salt in 100 grains. "This formula," adds the Doctor, " will often be of considerable use, as it serves as a kind of standard to which we may compare our analysis." System, vol. iii. p. 231. With solutions of nitre and common salt, it gives tolerable approximations ; and hence, I fancy, that from these solutions the rule must have been framed. But for solution of sulphate of soda, this kind of standard gives a quantity of dry salt nearly double, and for that of sal ammoniac, less than one-half the real quantity present. M. Gay Lussac published in the Ann. de Chimie et de Phys. xi. 296, an important memoir on the solubility of salts, from which I shall make a few extracts. One is astonished, says this excellent che- mist, on perusing the different chemical works, at the inaccuracy of our knowledge respecting the solubility of the salts. They satisfy themselves with the common observation, that the salts are more soluble in hot than in cold water, and with the solubility of a few of them at a temperature usually very uncertain ; yet it is upon this property of salts that their mutual decomposition, their separation, and the different processes for analyzing them depend. As a chemical process, the solution of the salts deserves peculiar attention ; for though the causes to which it is due are the same as those which produce other combina- tions, yet their effects are not similar. It is to be wished that this interesting part of chemistry, after remaining so long in vague generalities, may at last enter the domain of experiment, and that the solubility of each body may be determined, not merely for a fixed temperature, but for variable tempera- tures. In the natural sciences, and especially in chemistry, general conclusions ought to be the result of a minute knowledge of particular facts, and should not precede that knowledge. It is only after having acquired this know- ledge, that we can be sure of the existence of a common type, and that we can venture to state facts in a general manner. The determination of the quantity of salt which water can dissolve is not a very difficult process. It consists in saturating the water exactly with the salt whose solubility we wish to know at a determinate temperature, to weigh out a certain quantity of that solution, to evaporate it, and weigh the saline residue. However, the saturation of water may present considerable uncertainty; and before going further it is proper to examine the subject. We obtain a perfectly saturated saline solu- tion in the two following ways. By heating the water with the salt, and allowing it to cool to the temperature whose solubility is wanted ; or by putting into cold water a great excess of salt, and gradually elevating the temperature. In each case, it is requisite to keep the final temperature constant for two hours at least, and to stir the saline solution frequently, to be quite sure of its perfect saturation. By direct experiments made with much care, M. Gay Lussac ascertained that these two processes give the very same result, and that of consequence they may be employed indifferently. Yet Dr. Thomson says, he found that water retains more oxide of arsenic when saturated by cooling, than when put in contact with the oxide without any elevation of temperature; but the reason I am persuaded was, that he employed too little oxide of arsenic relatively SAL 686 SAL to the water, and that he did not prolong the contact sufficiently. We perceive in fact, on a little reflection, that saturation follows in its progress a decreasing geometrical progression, and that the time necessary for completing it depends upon the surface of contact of the solvent and the body to be dissolved. It happens often that the solution of a salt which does not crystallize, and which, for that reason, we consider as saturated, yields saline molecules to the crystals of the same nature plunged into it; and it has been concluded from this, that the crystals of a salt impoverish a solution, and make it sink below its true point of saturation. The fact is certain ; it is even very general ; but I am of opinion that it has been ill explained. Saturation in a saline solution of an inva- riable temperature is the point at which the solvent, always in contact with the salt, can neither take up any more, nor let go any more. This point is the only one which should be adopted, because it is determined by chemical forces, and because it remains constant as long as these forces remain constant. According to this definition, every saline solution which can let go salt without any change of temperature, is of necessity supersaturated. It may be shown that, in general, supersaturation is not a fixed point, and that the cause which pro- duces it is the same as that which keeps water liquid below the temperature at which it congeals. " I shall now give an account of the ex- periments which I have made on the solubility of the salts. " Having saturated water with a salt at a determinate temperature, as I have explained above, I take a matrass capable of holding 150 to 200 grammes of water, and whose neck is 15 to 18 centimetres in length. After having weighed it empty, it is filled to about a fourth part with the saline solution, and weighed again. To evaporate the water, the matrass is laid hold of by the neck by a pair of pincers, and it is kept on a red-hot iron at an angle of about 45, taking care to move it continually, and to give the liquid a rota- tory motion, in order to favour the boiling, and to prevent the violent bubbling up which is very common with some saline solutions, as soon as, in consequence of evaporation, they begin to deposit crystals. When the saline mass is dry, and when no more aqueous vapours are driven off at a heat nearly raised to redness, I blow into the matrass, by means of a glass tube fitted to the nozzle of a pair of bellows, in order to drive out the aqueous vapour which fills it. The matrass is then allowed to cool, and weighed. I now know the proportion of water to the salt held in solution, and this is expressed by representing the quantity of water to be 100. Each of the following results is the mean of at least two experiments : Solubility of Chloride of Potassium. Temperature Chloride dissolved by centigrade. 100 water. 0.00 29.21 19.35 34.53 52.39 43.59 79.58 50.93 109.60 59.26 Solubility of Chloride of Barium. Temperature centigrade. Salt dissolved in 100 water. 15.640 34.86 49.31 43.84 74.89 50.94 105.48 59.58 In these experiments, the chloride of barium is supposed to be anhydrous ; but as when it is crystallized it retains two proportions of water, 22-65, for one of chloride, 131.1, we must of necessity, in order to compare its solubility with that of other salts, increase each number of solubility by the same number multiplied into the ratio of 22.05 to 131.1, and diminish by as much the quantity of water. On making this correction, the pre- ceding results will be changed into the fol- lowing : Temperature. 15.640 49.31 74.89 105.48 Salt dissolved in loo water. 43.50 55.63 65.51 77-89 Solulility of Chloride of Sodium. Temperature. Salt dissolved in 100 water. 35.81 13.89 16.90 59.93 109.73 35.88 37-14 40.38 Solubility of Sulphate of Potash. Temperature. Salt dissolved in 100 water. 12.72 10.57 49.08 16.91 63.90 19.29 101.50 26.33 Solubility of Sulphate of Magnesia. Temperature. Salt dissolved in loo water. 14.58 32.76 39.86 45.05 49.08 49.18 64.35 56.75 97.03 72.30 The sulphate of magnesia is here supposed anhydrous; but as it crystallizes retaining seven portions of water, 79-3, for one proportion of salt, 74.6, each number which expresses the solubility, must be increased by this number multiplied by the ratio of 79.3 to 74.6, and the corresponding quantity of water diminished as much. We shall thus have for the solubility of crystallized sulphate of magnesia the following results : SAL 687 SAL Temperature. 14.58" 103.69 39.86 178.34 49.08 212.61 64.35 295.13 97.03 644.44 Solubility of Nitre. Temperature. Salt dissolved in loo water. 0.00" 13.32 5.01 16.72 11.67 22.23 17-91 29.31 These results are no longer proportional to the temperatures ; they augment in a much 24.94 35.13 45.10 38.40 54.82 74.66 greater ratio. 54.72 97-05 Solubility of Sulphate of Soda. 65.45 79-72 125.42 169.27 Salt soluble in 100 water. 97.66 236.45 Temperature. Anhydrous. Crystallized. 0.00 5.02 12.17 11.67 10.12 26.38 Solubility of Chlorate of Potash. 13.30 11.74 31.33 Temperature. 17.91 16.73 48.28 0.00 3.33 25.05 28.11 99.48 13.32 5.60 28.76 37-35 161.53 15.37 6.03 30.75 43.05 215.77 24.43 8.44 31.84 47.37 270.22 35.02 12.05 32.73 50.65 322.12 49.08 18.96 33.88 50.04 312.11 74.89 35.40 40.15 48.78 291.44 104.78 60.24 45.04 47-81 276.91 50.40 46.82 262.35 59.79 45.42 70.61 44.35 84.42 42.96 103.17 42.65 The principal uses of the have already been mentioned muriatic acid* In addition, served, that almost all grami muriate of sodi under the articl it may be ob nivorous animal We see by these results, that the solubility of sulphate of soda follows a very singular law. After having increased rapidly to about the temperature of 33, where it is at its maximum, it diminishes to 103.17, and at that point it is nearly the same as at 30.5. The sulphate of soda presents the second example of a body whose solubility diminishes as the temperature augments; for Mr. Dalton has already ob- served the same property in lime. Solubility of Nitrate of Barytes. Temperature. Salt dissolved iti 100 water. 0.00 5.00 14.95 8. 18 17-62 8.54 37.87 13.67 49.22 17.07 52.11 17-97 73.75 25.01 86.21 29.57 101.65 35.18 are fond of it, and that it appears to be bene- ficial to them, when mixed with their food. Wood steeped in a solution of it, so as to be thoroughly impregnated with it, is very diffi- cult of combustion : and in Persia it is sup- posed to prevent timber from the attack of worms, for which purpose it is used in that country. Bruce informs us, that in Abyssinia it is used as money ; and it is very probable, that the pillars of fossil glass, in which the Abyssinians are said by Herodotus to have enclosed the bodies of their relations, were nothing but masses of rock salt, which is very common in that part of Africa. Salt was supposed by the ancients to be so detrimental to vegetation, that, when a field was condemned to sterility, it was customary to sow it with it salt. Modern agriculturists, however, consider it as a useful manure. We are indebted to Dr. Henry for a very elaborate investigation of the different varieties of common salt. The following table contains the general statement of his experiments. SAL 688 SAL 1000 parts by weight consist of Kind of salt 2fSt. Ube's, E ^ < St. Martin's, \ftOleron, jg f Scotch (common), |r ) Scotch (Sunday), "*. |r J Lymington (com.), . jp f Ditto (cat), ^ f Crushed rock, I" J Fishery, r* 5! J Common, 3 f Stoved, II trace do. do. i 't Is HgS 28 II 2 5 f* 1 1 19 19^ 15 12 15 1 16 4 50 6 111 To muri 40 35f m Pure muriate of soda. 960 964 971 937 988 986 98 ct In sea salt prepared by rapid evaporation, the insoluble portion is a mixture of carbonate of lime with carbonate of magnesia, and a fine siliceous sand ; and in the salt prepared from Cheshire brine, it is almost entirely carbonate of lime. The insoluble part of the less pure pieces of rock salt is chiefly a marly earth, with some sulphate of lime. The quantity of this impurity, as it is stated in the table, is considerably below the average, which in my experiments has varied from 10 to 45 parts in 1000. Some estimate of its general propor- tion, when ascertained on a larger scale, may be formed from the fact, that Government, in levying the duties, allow 65 pounds to the bushel of rock salt, instead of 56 pounds, the usual weight of a bushel of salt." Henry. Phil. Trans, for 1810, part 1st. The con. tamination of the Scotch variety with that septic bitter salt, muriate of magnesia, accords perfectly with my own experiments. " That kind of salt, then," says this able chemist, " which possesses most eminently the combined properties of hardness, compactness, and perfection of crystals, will be best adapted to the purpose of packing fish and other pro- visions, because it will remain permanently between the different layers, or will be very gradually dissolved by the fluids that exude from the provisions ; thus furnishing a slow but constant supply of saturated brine. On the other hand, for the purpose of preparing the pickle, or of striking the meat, which is done by immersion in a saturated solution of salt, the smaller grained varieties answer equally well ; or, on account of their greater solubility, even better," provided they be equally pure. His experiments show, that in compactness of texture the large grained Bri- tish salt is equal to the foreign bay salt. Their antiseptic qualities are also the same. SAL 689 SAL _^ ji CV. A. O, *? O CO 00 S I s 3 i &.*?! S3 2 2 ! . cv. cv, O a. cv. &. g 'pr o ^ w > tf < J & << ^ I 0> _i ^- O^ rS 13 ^3,3 ^oa)^ f. ^^ ^ W 4.5 ,, 00^WOOJC3o S 3.1 I II S^I SAL 690 SAL i i a. ev. 6 O OJ co 2 N > >s w w , 6 o I* i^ > I j 3 & BlfJjfllJ 8 | g H a S g - '3 'S -2 53 8 . rs 5 ; r c X J 5 SJtl - SAL 691 SAL tO tO 2 6 co to O C^ H P.iOCD O -^ O CO C5 CO CO !N W 1 f II IS 02 W 05 >-02 s B S O S w H SI 00 " II is a 3 - o s^ PW PL, 3 OCO SAL 694 SAL r>.co >- co o - 1 fi CO rj H l I Sri aj|ss^ a O Q.3^ 1 'iOpL, C5O COiO *T *S & S>^8 sS*SS?^j|J2 SSs&?? I -o J^ I * .fteeJS O COOOkOkO CO O oo -> CO O fl, 8 S -2 g^.g a ill"' I 1 ^^'b 2 fcn^u 3 ii ilUli .S 'S e 2 S S CQUo ? O5 CO 3 1 il 1 3 I 05 l^S O C^ CO a S 00 o 3 ^ o o o G -w 8 e 3 go .5*P* s; 0) 0,0 3 63,3 6 ^ft,3 SO ffl! SAL 697 SAL H i j t Jl tSi - S t3 -s x *3 S2 | H i? till O2 O GG>- O OO 3..- ^1 ; il 18 :lfl fiiilll ISiIlli .til WMlHttlii 56gll|l!5 > K ; *2^j3llllllllllll'l > |-llttllH SS.S'5-Sg2iiSSS'S P^* 8.8,8,5 322 33*-E- SAL 700 SAL li a 11 si |i I ^ G cO O j v< PQ 02 s 3 00 IT 1 1 -al - fe 35 CO O C5 W o "? co o O O O g O H CO O pi,.. M SAL 701 SAL f I Q !^ *,.l fc co o CO . CO 5 PH 10 rj O i-l O is 81 -. So ^ a .s "9 ? SBaJSisUf'sli^ liquid flk soluti Liquid Four-sided IMassive Dark red Yellow i So w .H 4 - - SAL 704 SAL gco o ^ * r .*.S i Ml 1 Is wfr QQ CO o o o o fill g-3-g i CO CO CO ~ o 66 2-| IAU 1 jj - C* 3 OOCOOTf.i PS CO p 3 Q * 6 6 rf CO CS CO co o O5 o q> (N (N -H (N -^ * * i I j L.| ll!.i||,|l||JI||IMi si II .5 a I I III 111. l-i I i MCQ pq ooSoo SAL 705 SAL ;O CD CO CO o o o o g^o g^o .sr '3 ft 000 o O - 3 .A o ^a O *0 ai . _r & 9 I O 03 73 I, !, SAL 706 SAL I a 3 00 I rs i^bD 2j S.-SfeS-S^S S fSliillgi . . ||i a ^^-0,-! I o ^ JT da e? S -? m S ^-5 S3? SAL 707 SAL o <5 eo ? 4 CO s !0 CO .- 8 rf U3 IH O i i J3 t* 3 -O .i. ^0 4- ^w OS 53'* r}< ^' ^ S CQ JU . SAL |l 5 e o *J Water 212". jooi g oo 8,? ! 03 OJ C p " 1 CO .5 8 r 10 ^ S 5 03 C/5 i.l -2wo> B 5.9 ^S -311 M 1 -.1 1 s a ^2 f.-ll a "o^J o SSS.2 rjt CO I-H 1 If S 811 sT-3 c oooooj o o 00 ll SAL 712 SAP SALT (AMMONIACAL, FIXED). Muriate of Kme. SALT (AMMONIACAL, SECRET) OF GLAUBER. Sulphate of ammonia. SALT (ARSENICAL, NEUTRAL) OF MACQUER. Superarseniate of potash. SALT (BITTER, CATHARTIC). Sul- phate of magnesia. SALT (COMMON). Muriate of soda. See ACID (MURIATIC); also end of the article SALT, and ROCK SALT. SALT (DIGESTIVE) OF SYLVIUS. Acetate of potash. SALT (DIURETIC). Acetate of potash. SALT (EPSOM). Sulphate of magnesia. SALT (FEBRIFUGE) OF SYLVIUS. Muriate of potash. SALT (FUSIBLE). Phosphate of am- monia. SALT (FUSIBLE) OF URINE. Triple phosphate of soda and ammonia. SALT (GLAUBER'S). Sulphate of soda. SALT (GREEN). In the mines of Wiclizka the workmen give this name to the upper stratum of native salt, which is rendered impure by a mixture of clay. SALT (MARINE). Muriate of soda. SALT (MARINE ARGILLACEOUS). Muriate of alumina. SALT (MICRO COSMIC). Triple phos- phate of soda and ammonia. SALT (NITROUS AMMONIACAL). Nitrate of ammonia. SALT OF AMBER. Succinic acid. SALT OF BENZOIN. Benzoic acid. SALT OF CANAL. Sulphate of mag- nesia. SALT OF COLCOTHAR. Sulphate of iron. SALT OF EGRA. Sulphate of mag- nesia. SALT OF LEMONS (ESSENTIAL). Superoxalate of potash. SALT OF SATURN. Acetate of lead. SALT OF SEDL1TZ. Sulphate of mag- nesia. SALT OF SEIGNETTE. Triple tar- trate of potash and soda. SALT OF SODA. Subcarbonate of soda. SALT OF SORREL. Superoxalate of potash. SALT OF TARTAR. Subcarbonate of potash. S A LT OF VITR IOL. Purified sulphate of zinc. SALT OF WISDOM. A compound mu- riate of mercury and ammonia. See ALE M- BROTH. SALT (PERLATE). Phosphate of soda. SALT (POLYCHREST) OF GLASER. Sulphate of potash. SALT (SEDATIVE). Boracic acid. SALT (SPIRIT OF). Muriatic acid was formerly called by this name, which it still retains in commerce. SALT (SULPHUREOUS) OF STAHL. Sulphite of potash. SALT (W (WONDERFUL). Sulphate of soda. SALT (WONDERFUL PERLATE). Phosphate of soda. SALTPETRE. Nitrate of potash. SAND. Sand is an assemblage of small stones. SAND-BATH. See BATH. SANDARIC GUM. A resin in yellow- ish-white tears, possessing a considerable de- gree of transparency. SANDIVER, or GLASS- GALL. This is a saline matter, which rises as a scum in the pots or crucibles in which glass is made. SANGUIFICATION. That process of living animals by which chyle is converted into blood. I had entertained hopes of be- ing able to present some definite facts on this mysterious subject, but have been disappointed. The latest essay on sanguification is that of Dr. Prout, in the Annals of Philosophy for April, 1819. SAPPARE. CYANITE. SAPPHIRE. A sub-species of rhom- boidal corundum. It is the Telesie of Haily, and the perfect corundum of Boumon. The oriental ruby and topaz are sapphires. Colours blue and red ; it occurs also gray, white, green, and yellow. It occurs in blunt- edged pieces, in roundish pebbles, and crys- tallized. The primitive figure is a slightly acute rhomboid, or double three-sided pyramid, in which the alternate angles are 86 4' and 93 56'. The following are the usual forms : a very acute, equiangular, six-sided py- ramid ; the same truncated on the summit ; a perfect six-sided prism ; an acute, double, six-sided pyramid ; the same acuminated, or truncated in various ways. Splendent, inclined to adamantine. Cleavage parallel with the terminal planes of the prism. Fracture con- choidal. From transparent to translucent. Refracts double. After diamond, it is the hardest substance in nature. The blue variety, or sapphire, is harder than the ruby. Brittle. Sp. gr. 4 to 4.2. Its constituents are, Blue. Red. Alumina, 98.5 90.0 Lime, 6.5 7.0 Oxide of iron, 1. 1.2 Loss 1.8 100.0 Klaproth. 100.0 Chcnevlc. Infusible before the blowpipe. It becomes electrical by rubbing, and retains its electri- city for several hours ; but does not become electrical by heating. It occurs in alluvial soil, in the vicinity of rocks belonging to the SAT 718 SCA secondary or floetz-trap formation, and im- bedded in gneiss. It is found at Podsedlitz and Treblite in Bohemia, and Hohenstein in Saxony ; Expailly in France ; and particularly beautiful in the Capelan mountains, 12 days' journey from Sirian, a city of Pegu. Next to diamond, it is the most valuable of the gems. The white and pale blue varieties, by exposure to heat, become snow-white, and when cut exhibit so high a degree of lustre, that they are used in place of diamond. The most highly prized varieties are the crimson and carmine-red j these are the oriental ruby of the jeweller; the next is sapphire; and last, the yellow, or oriental topaz. The aste- rias, or star-stone, is a very beautiful variety, in which the colour is generally of a reddish- violet, and the form a rhomboid, with trun- cated apices, which exhibit an opalescent lustre. A sapphire of 10 carats weight is considered to be worth fifty guineas. Jameson. SAPHIRIN. HaUyne. SARCOLITE. A variety of analcime. SARDE, or SARDOIN. a variety of carnelian, which displays on its surface an agreeable and rich reddish -brown colour, but appears of a deep blood-red when held between the eye and the light SARDONYX. Another variety, composed of layers of white and red carnelian. SASSOLINE. Native boracic acid. It is found on the edges of hot springs near Sasso, in the territory of Florence. It consists of boracic acid 86, ferruginous sulphate of man- ganese 11, sulphate of lime 3. Klaproth. SATIN SPAR. Fibrous limestone; which see. SATURATION. Some substances unite in all proportions. Such, for example, are acids in general, and some other salts with water; and many of the metals with each other. But there are likewise many sub- stances which cannot be dissolved in a fluid, at a settled temperature, in any quantity be- yond a certain proportion. Thus water will dissolve only about one-third of its weight of common salt, and, if more be added, it will remain solid. A fluid, which holds in solu- tion as much of any substance as it can dis- solve, is said to be saturated with it. But saturation with one substance does not deprive the fluid of its power of acting on and dis- solving some other bodies, and in, many cases it increases this power. For example, water saturated with salt will dissolve sugar ; and water saturated with carbonic acid will dissolve iron, though without this addition its action on this metal is scarcely perceptible. The word saturation is likewise used in another sense by chemists. The union of two principles produces a body, the properties of which differ from those of its component parts, but resemble those of the predominating prin- ciple. When the principles are in such pro- portion that neither predominates, they are said to be saturated with each other ; but if otherwise, the most predominant principle is said to be subsaturated or undersaturated, and the other supersaturated or oversaturated SAUSSURITE. Colours white, gray, and green, massive, disseminated, and in rolled pieces. Dull. Fracture splintery. Faintly translucent on the edges. Difficultly fran- gible. Hard, scratching quartz. Meagre to the feel. Sp. gr. 3.2. It melts on the edges and angles. Its constituents are, silica 49, alumina 24, lime 10.5, magnesia 3.75, natron 5.5, iron 6.5. Klaproth. It occurs at the foot of Mount Rosa. Professor Jameson places it near Andalusite. SCALES OF FISH consist of alternate layers of membrane and phosphate of lime. SCALES OF SERPENTS are composed of a horny membrane, without the calcareous phosphate. SCAMMONY consists of Aleppo. Smyrna. Resin, 60 29 Gum, 3 8 Extractive, 2 5 Vegetable debris \ * * and earth j 35 100 100 Vogel, and Bouillon Lagrange. SCAPOLITE, OR PYRAMIDAL FEL- SPAR. Professor Jameson divides it into four sub-species ; radiated, foliated, compact red, and elaolite. 1. Radiated. Colour gray. Massive, in distinct concretions and crystallized. Primi- tive figure a pyramid of 136 38' and 62 56'. The secondary forms are, a rectangular four, sided prism, acuminated or truncated. La- teral planes deeply longitudinally streaked. Resinous, pearly. Cleavage double. Frac- ture fine grained uneven. Translucent. As hard as apatite. Easily frangible. Sp. gr. 2.5 to 2.8. Green scapolite becomes white before the blowpipe, and melts into a white glass. Its constituents are, silica 45, alumina 33, lime 17-6, natron 1.5, potash 0.5, iron and manganese 1. Laugier. It occurs in the neighbourhood of Arendal in Norway, associated with magnetic ironstone, felspar, &c. 2. Foliated scapolite. Colours gray, green, and black. Massive, disseminated, and crys- tallized in low eight-sided prisms, flatly acu- minated with four planes. Splendent, vi- treous. Fracture small grained uneven. Translucent. Streak white; Brittle. Hard- ness and sp. gr. as preceding species. It is found in granular granite or ivhitestone, in the Saxon Erzegebirge. 3. Compact scapolite. Colour red. Crys- tallized in long, acicular, four-sided prisms, which are often curved. Glistening. Opaque. Hard in a low degree. Easily frangible. It occurs with the others in metalliferous beds at Arendal. SEL 714 SEL 4. See ELAOLITE. SCHAALSTETN. See TABULAR SPAU. SCHAUM EARTH. See APHRITE. SCHEELIUM. Tungsten. SCHIEFER SPAR. See SLATE SPAR. SCHILLER SPAR. This species con- tains two sub-species ; bronzite and common schiller spar. See BRONZITE. Common schiller spar. Colour olive-green. Disseminated, and in granular distinct con- cretions. Splendent and metallic -pearly. Cleavage single. Opaque. Softer than bronzite. Streak greenish-gray. Easily fran- gible. Sp. gr. 2.882? It occurs imbedded in serpentine in Fetlar and Unst in Shetland, and at Portsoy in Banffshire ; also in Skye, Fifeshire, Calton-hill, near Dumbarton, be- tween Ballantrae and Girvan in Ayrshire, and in Cornwall. Lalradore schilkr spar. See HYPER- STENE. SCHMELZSTEIN. Dipyre. SCHORL (COMMON). A sub-spe- cies of rhomboidal tourmaline. Colour vel- vet-black. Massive, disseminated, and crys- tallized, in three, six, and nine-sided prisms. Crystals acicular. Lateral planes longitudi- nally streaked. Between shining and glis- tening. Fracture conchoidal, or uneven. Opaque. Streak gray. As hard as quartz. Easily frangible. Sp. gr. 3 to 3.3. It melts into a blackish slag. Its constituents are, silica 36.75, alumina 34.5, magnesia 0.25, oxide of iron 21, potash 6, and a trace of manganese. Klaproth. It exhibits the same electric properties as tourmaline. It occurs imbedded in granite, gneiss, &c. in Perth- shire, Banffshire, Cornwall, &c. SCHORL (BLUE). A variety of Hauyne. SCHORL (RED AND TITANITIC). Rutile. SCHORLITE, or SCHORLOUS TO- PAZ. Pycnite of Werner. Colour straw- yellow. Massive, composed of parallel prisma- tic concretions, and crystallized in long six- sided prisms. Glistening, resinous. Fracture, small conchoidal. Translucent on the edges. Nearly as hard as common topaz. Brittle. Sp. gr. 3.53. Infusible. Becomes electric by heating. Its constituents are, alumina 51, silica 38.43, fluoric acid 8.84. Berzettus. It occurs at Altenberg in Saxony, in a rock of quartz and mica in porphyry. SCILLITIN. A white transparent, acrid substance, extracted from squills, by Vogel. SELENIUM. A new elementary body, extracted by M. Berzelius from the pyrites of Fahlun, which, from its chemical properties, he places between sulphur and tellurium, though it has more properties in common with the former than with the latter substance. It was obtained in exceedingly small quantity from a large portion of pyrites. For the mode of extraction I must refer to his long and ela- borate papers, translated from the Annales de Chlmie et de Physique, ix. et cq. into the Annals of Philosophy, for June, August, October, and December 1819, and January, 1820. Professor Stromeyer has lately discovered selenium under two different forms, one of which is altogether new. On diluting some fuming sulphuric acid, such as is made at Nordhausen from the sulphate of iron, he ob- served that a solid matter separated, which on examination proved to be selenium. One pound of the acid gave on dilution about one grain of selenium. The second source of selenium is in the volcanic productions of the Lipari islands, among which Professor Stro- meyer has lately discovered a native sulphuret of selenium. Selenium has also been detected in the Anglesea pyrites. The sulphuric acid made from it having been used in making muriatic acid, the selenium is seen to distil over into the receivers, in the course of two or three days falling down as a reddish brown substance. A portion of this selenium, tested by Mr. Children, gave when heated on pla- tinum foil by a spirit lamp, an azure-blue tinge to the flame. The smell of horse-radish was perceptible, when the substance was heated in a glass tube. In thin laminse it was trans- parent, and of a beautiful cinnabar red colour. Annals of Phil. N. S. ix. 52. When selenium, after being fused, becomes solid, its surface assumes a metallic brilliancy of a very deep brown colour, resembling po- lished haematites. Its fracture is conchoidal, vitreous, of the colour of lead, and perfectly metallic. The powder of selenium has a deep red colour, but it sticks together readily when pounded, and then assumes a gray colour and a smooth surface, as happens to antimony and bismuth. In very thin coats, selenium is transparent, with a ruby-red colour. When heated it softens ; and at 212 it is semi-liquid, and melts completely at a temperature a few degrees higher. During its cooling it retains for a long time a soft and semi-fluid state. Like Spanish wax, it may be kneaded be- tween the fingers, and drawn out into long threads, which have a great deal of elasticity, and in which we easily perceive the transpa- rency, when they are flat and thin. These threads, viewed by transmitted light, are red ; but, by reflected light, they are gray, and have the metallic lustre. When selenium is heated in a retort, it begins to boil at a temperature below that of a red heat. It assumes the form of a dark yel- low vapour, which, however, is not so intense as that of the vapour of sulphur ; but it is more intense than chlorine gas. The vapour condenses in the neck of the retort, and forms black drops, which unite into larger drops, as in the distillation of mercury. If we heat selenium in the air, or in vessels so large that the vapour may be condensed by the cold air, a red smoke is formed, which has SEL 715 SEL no particular smell, and which is condensed in the form of a cinnabar-red powder, yielding a species of flowers, as happens to sulphur in the same circumstances. The characteristic smell of horse-radish is not perceived, till the heat becomes great enough to occasion oxida- tion. Selenium is not a good conductor of heat. We can easily hold it between the fingers, and melt it at the distance of one or two lines from the fingers, without perceiving that it becomes hot. It is also a non-conductor of electricity. On the other hand, M. Berzelius was not able to render it electric by friction. It is not hard ; the knife scratches it easily. It is brittle like glass, and is easily reduced to powder. Its sp. gr. is between 4.3 and 4.32. The affinity of selenium for oxygen is not very great. If we heat it in the air, without touching it with a burning body, it is usually volatilized, without alteration; but if it is touched by flame, its edges assume a fine sky-blue colour, and it is volatilized with a strong smell of horse-radish. The odorous substance is a gaseous oxide of selenium, which, however, has not been obtained in an insulated state, but only mixed with atmo- spherical air. If we heat selenium in a close phial filled with common air, till the greatest part of it is evaporated, the air of the phial acquires the odour of oxide of selenium in a very high degree. If we wash the air with pure water, the liquid acquires the odour of the gas ; but as there are always formed traces of selenic acid, this water acquires the pro- perty of reddening litmus paper feebly, and of becoming muddy when mixed with sul- phuretted hydrogen gas. Selenic oxide gas is but very little soluble in water, and does not communicate any taste to it. If we heat selenium in a large flask filled with oxygen gas, it evaporates without com- bustion, and the gas assumes the odour of selenic oxide, just as would have happened if the sublimation had taken place in com- mon air; but if we heat the selenium in a glass ball of an inch diameter, in which it has not room to volatilize and disperse ; and if we allow a current of oxygen gas to pass through this ball, the selenium takes fire, just when it begins to boil, and burns with a fee- ble flame, white towards the base, but green or greenish-blue at the summit, or towards the upper edge. The oxygen gas is absorbed, and selenic acid is sublimed into the cold parts of the apparatus. The selenium is completely consumed without any residue. The excess of oxygen gas usually assumes the odour of selenic oxide. Selenic acid is in the form of very long four-sided needles. It seems to be most readily formed by the action of nitro- muriatic acid on selenium. The selenic acid docs not melt with heat ; but it diminishes a little in bulk at the hottest place, and then assumes the gaseous form. It absorbs a little moisture from the air, so that the crystals ad- here to each other, but they do not deliquesce. It has a pure acid taste, which leaves a slightly burning sensation on the tongue. It is very soluble in cold water, and dissolves in almost every proportion in boiling water. M. Ber- zelius infers the composition of selenic acid, from several experiments, to be, Selenium, 71-261 100-00 1 prime 4-96 Oxygen, 28-739 40-33 2 primes 2-00 If into a solution of selenic acid hi muriatic acid, we introduce a piece of zinc or of polished iron, the metal immediately assumes the colour of copper, and the selenium is gradu- ally precipitated in the form of red, or brown, or blackish flocks, according as the tempera- ture is more or less elevated. When seleniate of potash is heated with muriate of ammonia, selenium is obtained by the deoxidizing pro- perty of the ammonia ; but in this case we always lose a small quantity of selenium, which comes over with the water in the form of an acid. If we pour dilute muriatic acid on the compound of selenium and potassium dissolved in water, seleniuretted hydrogen gas is evolved. Water impregnated with it pre- cipitates all the metallic solutions, even those of iron and zinc, when they are neutral. Sul- phur, phosphorus, the earths, and the metals, combine with selenium, forming seleniurets. Selenic acid neutralizes the bases. Selenium has been recently found in two minerals ; one is from Skrickerum, in the parish of Tryserum in Smoland. M. Henry Rose of Berlin has lately pub- lished an interesting memoir on the native seleniurets, found in the Oriental Hartz, dis- seminated in magnesian limestone, in the veins of iron that traverse argillaceous schist. He converted all the metals present into chlorides, by passing chlorine over the pul- verized ore for half a day, and separated the chloride of selenium by means of its vola- tility. 1. Seleniuret of lead. This was the most frequent. It consists of two atoms of selenium to one of lead ; consisting of 27-7 selenium + 72-3 lead. 2. Seleniuret of lead and cobalt. Its consti- tuents are, Lead, - - 63-92 Cobalt, - 3-14 Selenium, 31-42 Iron, 0-45 Loss, 1-07 100-00 3. Seleniuret of lead and copper. Of this mineral there were two varieties composed as follows : SER 716 SID Selenium, 29-96 Iron with traces of lead, 044 Lead, 69-67 Iron, 0-33 Copper, 7-86 Undecomposed portion ) of the mineral, 34-26 2-08 47-43 15-45 1-29 Loss, 0-74 100-00 100-51 4. Selcnluret of lead and mercury ', contains Selenium, 24-97 Lead, . . 55-84 Mercury, 16-94 2-25 100-00 Ann. de Chim., xxix. 113. SCORZA. A variety of epidote. SEA FROTH. Meerschaum. SEA SALT. Muriate of soda. See ACID (MURIATIC), and SALT. SEA SALT (REGENERATED). Mu. riate of potash. SEA WAX. Maltha, a white, solid, tal- lowy-looking fusible substance, soluble in alcohol, found on the Baikal Lake in Siberia. SEBACIC ACID. See ACID (SEBACIC). SEBAT. A neutral compound of sebacic acid with a base. SEDATIVE SALT. Boracic acid. SEL DE SEIGNETTE. The triple tartrate of potash and soda, or Rochelle salt. See ACID (TARTARIC). SELENITE. Sparry gypsum. SEMIOPAL. See OPAL. SEPTARIA, or ludi helmontii, are sphe- roidal concretions, that vary from a few inches to a foot in diameter. When broken in a longitudinal direction, we observe the interior of the mass intersected by a number of fissures, by which it is divided into more or less regu- lar prisms, of from 3 to 6 or more sides, the fissures being sometimes empty, but oftener filled up with another substance, which is ge- nerally calcareous spar. The body of the con- cretion is a ferruginous marie. From these septaria are manufactured that excellent material for building under water, known by the name of Parker's or Roman cement. Jam wow. SEROSITY. See BLOOD. SERPENTINE ; common, and precious. 1. Common. Colour green, of various shades- Massive. Dull. Fracture small and fine splintery. Translucent on the edges. Soft, and scratched by calcareous spar. Sec- tile. Difficultly frangible. Feels somewhat greasy. Sp. gr. 2-4 to 2-6. Some varieties are magnetic. Its constituents are, silica 32, magnesia 37-24, alumina 0-5, lime 10-6, iron 0-66, volatile matter and carbonic acid 14-16. Hisinger. John and Rose give 10-5 of water in it. It occurs in various moun- tains. It is found in Unst and Fetlar in Shetland; at Portsoy; between Ballantrae and Girvan ; in Cornwall ; and in the county of Donegal. 2. Precious serpentine. Of this there are two kinds, the splintery and conchoidal. a. Splintery. Colour dark leek-green. Massive. Feebly glimmering. Fracture coarse splintery. Feebly translucent. Soft. Sp. gr. 2-7- It occurs in Corsica, and is cut into snuff-boxes, &c. b. Conchoidal. Colour leek-green. Massive and disseminated. Glistening, resinous. Frac- ture flat conchoidal. Translucent Semihard. Sp. gr. 2-6. Its constituents are, silica 42-5, magnesia 38-63, lime 0-25, alumina 1, oxide of iron 1*5, oxide of manganese 0-62, oxide of chrome 0-25, water 15-2. John. It occurs with foliated granular limestone in beds sub- ordinate to gneiss, mica- slate, &c. It is found at Portsoy, in BanfFshire; in the Shet- land Islands, and in the Island of Holyhead. It receives a finer polish than common ser- pentine. SERUM. See BLOOD and MILK. SHALE. Slate-clay and bituminous slate- clay. SHELLS. Marine shells may be divided, as Mr. Hatchett observes, into two kinds : those that have a porcellanous aspect, with an enamelled surface, and when broken are often in a slight degree of a fibrous texture ; and those that have generally, if not always, a strong epidermis, under which is the shell, principally or entirely composed of the sub- stance called nacre, or mother-of-pearl. The porcellanous shells appear to consist of carbonate of lime, cemented by a very small portion of animal gluten. This animal gluten is more abundant in some, however, as in the patella?. The mother-of-pearl shells are composed of the same substances. They differ, how- ever, in then- structure, which is lamellar, the gluten forming their membranes, regu- larly alternating with strata of carbonate of lime. In these two the gluten is much more abundant. Mr. Hatchett made a few experiments on land shells also, which did not exhibit any differences. But the shells of the crustaceoua animals he found to contain more or less phos- phate of lime, though not equal in quantity to the carbonate, and hence approaching to the nature of bone. Linnaeus therefore, he observes, was right in considering the covering of the echini as crustaceous, for it contains phosphate of lime. In the covering of some of the species of asterias, too, a little phos- phate of lime occurs ; but in that of others there is none. Phil. Trans. SHISTUS (ARGILLACEOUS). Clay- slate. SIBERITE. Red tourmaline. SIDERO-CALCITE. Brown spar. SIDERUM. Bergmann's name for phos- phuret of iron. SIL 717 SIL SIENITE OB SYENITE. A compound granular aggregated rock, composed of felspar and hornblende, and sometimes quartz and black mica. The hornblende is the charac- teristic ingredient, and distinguishes it per- fectly from granite, with which it is often con- founded ; but the felspar, which is almost always red, and seldom inclines to green, forms the most abundant and essential ingre- dient of the rock. Some varieties contain a very considerable portion of quartz and mica, but little hornblende. This is particularly the case with the Egyptian varieties, and hence these are often confounded with real granite. As it has many points of agreement with greenstone, it is necessary to compare them together. In greenstone, the hornblende is usually the predominating ingredient ; in sie- nite, on the contrary, it is the felspar that pre- dominates. In greenstone, the felspar is almost always green, or greenish ; here, on the con- trary, it is as constantly red, or reddish. Quartz and mica are very rare in greenstone, and in inconsiderable quantity ; whereas they are rather frequent in sienite. Lastly, green- stone commonly contains iron pyrites, which never occurs in sienite. It has either a simple granular base, or it is granular porphyritic ; and then it is deno- minated porphyritic sienite. When the parts of the granular base are so minute as to be distinguished with difficulty, and it contains imbedded in it large crystals of felspar, the rock is termed sienite-porphyry. It is some- times unstratified, sometimes very distinctly stratified. It sometimes shows a tendency to the columnar structure. It contains no foreign beds. It occurs in unconformable and overlying stratification, over granite, gneiss, mica-slate, and clay-slate, and is pret- ty continuous, and covers most of the primi- tive rocks. It is equally metalliferous with porphyry. In the island of Cyprus, it affords much copper ; many of the important silver and gold mines in Hungary are situated in it. The sienite of the forest of Thuringia affords iron. In this country, there is a fine example of sienite in Galloway, where it forms a con- siderable portion of the hill called Criffle. On the continent, it occurs in the electorate of Saxony ; and in Upper Egypt, at the city of Syena, in Thebaid, at the cataracts of the Nile, whence it derives its name. The Ro- mans brought it from that place to Rome, for architectural and statuary purposes. Jameson. SILICA. One of the primitive earths, which in consequence of Sir H. Davy's re- searches on the metallic bases of the alkalis and earths, has been recently regarded as a compound of a peculiar combustible principle with oxygen. If we ignite powdered quartz with three parts of pure potash in a silver crucible, dissolve the fused compound in water, add to the solution a quantity of acid, equi- valent to saturate the alkali, and evaporate to dryness, we shall obtain a fine gritty powder, which being well washed with hot water, and ignited, will leave pure silica. By passing the vapour of potassium over silica in an ig- nited tube, Sir H. Davy obtained a dark- coloured powder, which apparently contained silicon, or silicium, the basis of the earth. Like boron and carbon, it is capable of sus- taining a high temperature without suffering any change. Aqueous potash seems to form with it an olive- coloured solution. But as this basis is decomposed by water, it was not possible to wash away the potash by this liquid. Berzelius and Stromeyer tried to form an alloy of silicon or silicium with iron, by exposing to the strongest heat of a blastfur- nace, a mixture of three parts of iron, 1-5 silica, and 0-66 charcoal. It was in the state of fused globules. These freed from the charcoal were white and ductile, and their solution in muriatic acid evolved more hydro- gen than an equal weight of iron. The sp. gravity of the alloy was from 6-7 to 7-3, while that of the iron used was 7-8285. From Mr. Mushet's experiments, however, as well as from the constitution of plumbago, we know that carbon will combine with iron in very considerable proportions, and that in certain quantities it can give it a whitish colour and inferior density. Nothing absolutely definitive therefore can be inferred from these experiments. See IRON. M. Berzelius has lately obtained pure sili. cium by the combustion of potassium in silicated fluoric gas ; as also by the action of potassium on the double fluate of silica and potash, or of silica and soda. The latter salt having the advantage of containing a greater quantity of fluate of silica, under the same weight and bulk, deserves the preference. The salt is easily prepared by saturating aqueous silicated fluoric acid with carbonate of soda, when the very sparingly double salt precipitates, which is to be washed and dried, at a temperature considerably above 212 F. This dry matter in fine powder is to be stra- tified, with thin slices of potassium, in a glass tube sealed at the end, which is to be uni- formly heated at once with a spirit flame. Even before ignition, the silicium is reduced with a slight hissing sound, and some appear- ance of heat. No gas is disengaged when the salt has been well dried. The mass is allowed to cool. It is hard, agglutinated, porous, of a deep brown colour, which does not alter in the air, merely exhaling the smell of hydro- gen, as manganese does, when pressed between the fingers, or breathed upon. It is to be washed with water in successive quantities to remove the fluate of potash that is formed. Some gas is disengaged, but this soon ceases, and though the water be raised to ebullition, the brown powder does not decompose it. The solution obtained by ebullition being very acid, the substance is to be boiled with new portions of water till the liquid manifests no SIL 718 SIL signs of acidity, when it is to be passed through a filter. The powder, being dried, is of a chestnut brown (maroon) colour, containing visibly heterogeneous points of a brighter hue. The first of the above washings should be with a large quantity of water, so that the liquid which becomes alkaline by the oxidize- ment of the potassium may be so dilute as to have no tendency to oxidize the silicium and to dissolve it For this reason, the mass must not be treated with hot water till all the al- kalinity be removed. It is thereafter to be treated with boiling water, till a drop of this leaves no stain on evaporation. This process requires much time and a large body of water. Silicium^ obtained by this process, contains some hydrogen, but in less quantity, and pro- bably in the same way as the charcoal of wood, which Sir H. Davy regards as hydro- genated carbon. It contains, besides, some silica, which proceeds from a small portion of the potassium getting oxidized at first, and in this state separating a little silica from the double salt. The hydrogenated silicium is to be heated for some time almost to redness in an open crucible, then it is finally to be ig- nited. Should the silicium offer to take fire, the crucible is to be instantly covered, and the heat lowered, which will immediately stop the inflammation. After this calcination, the sili- cium is incombustible in the air, and may be washed from its adhering silica by pure liquid fluoric acid, taking care that no iron or man- ganese is present ; for the alloy thence result- ing would dissolve entirely with disengage- ment of hydrogen. After being treated with this acid, the silicium is to be washed and dried. Obtained in this way, silicium has a deep nut-brown colour, but not the least metallic lustre. When rubbed with a steel burnisher it presents no trace of brilliancy, opposing a resistance to friction, like an earthy substance. It is incombustible in the atmospheric air, and in oxygen gas. It suffers no change in the flame of the blowpipe, apparently belong- ing to the most infusible class of bodies. These properties appear at variance with what takes place with the silicium immediately after its reduction by potassium, for it readily burns. M. Berzelius ascribes this difference to the presence of hydrogen in the latter substance, which may be regarded as a siliciuret of po- tassium at first, and after simple washing a hydrurct of silicium. Ignition, well regulated, expels the hydrogen, without setting the com- pound on fire ; but if hastily induced, the hy- drogen kindles the silicium, which then be- comes covered with a coat of silica. The con- densation which the silicium undergoes by ig- nition, is the cause of its becoming insoluble in fluoric acid. Silicium stains and sticks strongly, even when dry, to the glass vessels in which it is kept. Silicium docs not conduct electricity. After its ignition, it is not affected by clilorate of potash, even at a red heat ; nor by nitre, till the temperature have become high enough to decompose the nitric acid, and to allow the affinity of its alkaline base to act. At a white heat, nitre attacks it violently. With carbonate of potash, silicium burns very readily with a lively flame. Gaseous oxide of carbon is disengaged, and the mass blackens from intermixture with charcoal. By taking a small proportion of carbonate of pot- ash, or of soda, as one half the bulk of the silicium, the inflammation takes place much below ignition. With larger proportions of the carbonate, the mass swells up from the development of the gaseous oxide of carbon, takes fire, and burns with a blue flame. With a still greater proportion there is no sign of combustion ; the mass does not blacken, but merely exhales the above gaseous oxide. If the incombustible silicium be heated to moderate redness on platinum foil with nitre, no effect ensues ; but if a bit of dry carbonate of soda be made to touch the silicium, a de- tonation will take place at the expense of the carbonate, and the mass will retain for some time its black colour. Silicium explodes with lively incandescence with the hydrated fixed alkalis at their melt- ing temperature, much below a red heat. Hydrogen is disengaged, which burns visibly when the bulk of the materials is not too small. The same phenomenon takes place with hydrate of barytes. With acid fluate of potash, silicium explodes at the melting point of the salt, which is far under ignition. It is not altered by borax in a state of fusion. Silicium, heated to distinct redness in the vapour of sulphur, takes fire and burns, but much less vividly than in oxygen; but the combination will not take place with the in- combustible silicium. In moist air, sulphuret of silicium diffuses a strong smell of sulphur- etted hydrogen, and speedily loses all its sul- phur ; but in dry air it may be preserved for a long time. At a red heat, it is roasted, affording sulphurous acid and silica. Siliciuret of potassium combines readily at a red heat with sulphur, constituting a true double sulphuret of a deep brown or black colour. Simple sulphuret of silicium, when thrown into water, dissolves immediately, with dis- engagement of sulphuretted hydrogen. The silicium changes into silica, which dissolves in the water, and if this be in small quantity, such a concentrated solution may be obtained as to gelatinize after a slight evaporation, and to leave silica, after drying, in a transparent cracked mass. It is remarkable to see silica dissolve in such a large proportion in water, at the instant of its formation, and to lose this property by evaporation to such a degree as to become insoluble in acids. This solubility SIL 719 SIL may explain the origin of the crystallizations of silica in drusy cavities, which in many cases could not contain a volume of liquid appre- ciably larger than that of the crystals them- selves. M. Berzelius did not succeed in combining silicium with phosphorus. Wh,en silicium is heated in a current of chlorine, it takes fire, and continues to burn. If the gas contain some atmospheric ah*, silica remains in a slender skeleton form. Silicium burns equally well in chlorine, whether or not it had previously been deprived of its com- bustibility in air. The product condenses into a liquid, which is yellowish with excess of chlorine, but colourless when this is expelled. This liquid is very fluid ; it evaporates almost instantaneously in the open air, affording white vapours, and leaving a little silica. It has a very penetrating odour, which may be com- pared to that of cyanogen. Thrown into water, it floats, then dissolves in it, and leaves some silica. When silicium is heated in vapour of po- tassium, it takes fire, producing a compound of silicium and potassium. The iodide of po- tassium does not unite with silicium. Silicium is neither dissolved nor acted upon by the sulphuric, nitric, and muriatic acids, nor even by the nitro-muriatic. But it dis- solves rapidly even in the cold, in a mixture of nitric and fluoric acid, with disengagement of nitrous gas. Combustible silicium dissolves on digestion in water of caustic potash ; but in its incombustible state it is not affected by the alkalis in the moist way. Silicium, once insulated, combines very re- luctantly with the metals. Its remarkable affinity for platinum is known, from the ex- periments of M. Boussingautt ; but it may be heated as often and as long as we please in a platinum crucible, without any combination taking place. But when we try to reduce silicium (from silica) by potassium, in a pla- tinum crucible, the silicium penetrates deeply into the platinum, in the spot where the potas- sium presses. 100 parts of pure silicium, dried in vacua, were heated with carbonate of soda. The mass, treated with muriatic acid, evaporated to dryness, and strongly heated, was then dis- solved in water. It left silica coloured gray by charcoal, which being washed and ignited, became snow-white, and weighed 203-75 parts. A little silica was afterwards procured from the washings, making in all 205-25. Hence 100 parts of silicium had absorbed 105-25 of oxygen. In another experiment, 208 parts of silica were obtained from 100 of silicium. Hence silica consists of Silicium, 48-5 Oxygen, 51-5 1000 The proportion which M. Berzelius inferred from the capacity of saturation of silica with the saline bases, was 50-3 oxygen to 49-7 sili- cium. The number of atoms of oxygen in silica has not been determined. M. Berzelius is in- clined to consider it as a tritoxide, and to call the atom of silicium 277 oxygen, being 100, or 2-77 oxygen = 1. Silicium does not seem to belong to the metallic class of bodies, but rather resembles carbon and boron. Some philosophical me- thodists, says Berzelius, will consequently give it the name of silicon ; but I regard this de- nomination as useless, since there is no true limit between the metals and the metalloids (such as boron and carbon). Carbon has the metallic lustre, and conducts electricity, and still it is not reckoned a metal. If silicium could be fused, it would possibly acquire the properties wanting in its pulverulent state. Uranium, in this form, can hardly be distin- guished by its aspect from silicium ; but when crystallized, it has the metallic lustre. Co- lumbium and titanium approach also to sili- cium in their chemical properties. Finally, when the electrical relation of a body is re- garded as its only decisive feature, it is in- different whether we place a combustible body among the metals or not. Annales de Chim. et Phys. xxvii. 337. I have already mentioned, in treating of earths, that Mr. Smithson had ingeniously suggested, that silica might be viewed in many mineral compounds as acting the part of an acid. This, however, is a vague analogy, and cannot justify us in ranking silica with acid bodies. When obtained by the process first de- scribed, silica is a white powder, whose finest particles have a harsh and gritty feel. Its sp. gr. is 2-66. It is fusible only by the hy- droxygen blowpipe. The saline menstruum, formed by neutralizing its alkaline solution with an acid, is capable of holding it dis- solved, though silica seems by experiment to be insoluble in water. Yet in the water of the Geyser spring a portion of silica seems to remain dissolved, though the quantity of al- kali present appears inadequate to the effect. Silica exists nearly pure in transparent quartz or rock crystal. It forms also the chief con- stituent of flints. By leaving a solution of silica in fluoric acid, or in aqueous potash, undisturbed for a long time, crystals of this earth have been obtained. The solution in alkaline lixivia is called liquor silicum. Glass is a compound of a similar nature, in which the proportion of silica is much greater. Mr. Kirwan made many experiments on the mutual actions of silica and the other earths, at high degrees of heat. The follow- ing are some of his results : SIL 720 SIL Proportions. 80 silica, 20 barytes, 75 silica, 25 barytes, 66 silica, \ 33 barytes, f 50 silica, 1 50 barytes, J 20 silica, > 80 barytes, $ 25 silica, 75 barytes, 33 silica, 66 barytes, f Heat. 150 Wedg. 150 150 148 148 150 150 A white brittle mass. A brittle hard mass, semitransparent at the edges. Melted into a hard somewhat porous porcelain. A hard mass, not melted. The edges were melted into a pale greenish matter, be- tween a porcelain and enamel. Melted into a somewhat porous porcelain mass. Melted into a yellowish and partly greenish-white po- rous porcelain. When the barytes exceeds the silica in the nearly the same as those with barytes. Lime proportion of three to one, the fused mass is water added to the liquor silicum, occasions a soluble in acids, -a circumstance recently precipitate which is a compound of the two applied with great advantage in the analysis of earths. The following are Mr. Kirwan's re- minerals which contain alkaline matter. suits in the dry way : The habitudes of strontian with silica are Proportions. 50 lime, 50 silica, 80 lime, 20 silica, 20 lime, 80 silica, Heat. Effects. Melted into a mass of a white colour, semitransparent jes, and striking fire, though feebly, with steel : was intermediate between porcelain and enamel. A yellowish-white loose powder. a brittle mass. When exposed to the magnesia and silica, in er white enamel. Silica and alumina unite both in the liquid and dry way. The latter compound consti- tutes porcelain and pottery-ware. Equal parts of lime, magnesia, and silica, melt, according to Achard, into a greenish- coloured glass, hard enough to strike fire with steel. When the magnesia exceeds either of the other two ingredients, the mixture is infu- sible ; when the silica exceeds, the only fusible proportions were, 3 silica, 2 lime, 1 magnesia ; and when the lime is in excess, the mixture usually melts in a strong heat With mix- tures of lime, alumina, and silica, a fusible compound is usually obtained when the lime predominates. The only refractory propor- tions were, Lime, 2 3 Silica, 1 1 Alumina, 2 2 Excess of silica gives a glass or porcelain, but excess of alumina will not furnish a glass. When, in mixtures of magnesia, silica, and alumina, the first is in excess, no fusion takes place at 150; when the second exceeds, a porcelain may be formed ; and 3 parts of silica, 2 magnesia, and 1 alumina, form a glass. From Achard's experiments it would appear that a glass may be produced by exposing to a ig heat, equal parts of alumina, silica, lime, and magnesia. Other proportions gave fusible mixtures, provided the silica was in excess. The mineral sommite, or nephelin, consists, according to Vauquelin, of 49 alumina + 46 silica. If we suppose it to consist of a prime equivalent or atom of each constituent, then that of silica would be 3 ; for 49 : 3-2 : : 46 : 3. But if we take Vauquelin's analysis of euclase for the same purpose, we have the proportion of silica to that of alumina as 35 to 22. Hence, 22 : 32 : : 35 : 5-09 the prime equivalent of silica, which is not reconcileable to the above number, though it agrees with that deduced from Sir H. Davy's experiments on silicon. I give these examples to show how unprofita- ble such atomical determinations are. See IRON and ACID (FLUOSILICIC). SILK. See BLEACHING, and APPEN- DIX. SILLIMANITE. A new mineral from Saybrook in Connecticut. Colour dark gray, passing into clove brown. It occurs in a vein of quartz, penetrating gneiss, crystallized in rhomboidal prisms, whose angles are about 106 30' and 73 10'; the inclination of the base to the axis of the prism being about 113. The sides and angles of the crystals are fre- quently rounded. In hardness it exceeds quartz ; and in some specimens, topaz. Trans- lucent in small fragments. Brittle. Frac- SIL ture in the longer diagonal lamellar, brilliant. Cross fracture uneven and splintery. Sp. gr. 3-41. Infusible at the blow-pipe, even with borax. Acids have no action on it. Its con- stituents are, Silica, 42-GG6 Alumina, 54-111 Oxide of iron, 1-999 Water, 0-510 Loss, 0-714 100-000 SILVAN. Tellurium, so caUed by Wer- ner. SILVER is the whitest of all metals, con- siderably harder than gold, very ductile and malleable, but less malleable than gold ; for the continuity of its parts begins to break when it is hammered out into leaves of about the hundred and sixty thousandth of an inch thick, which is more than one-third thicker than gold leaf; in this state it does not transmit the light. Its specific gravity is from 10-4 to 10-5. It ignites before melting, and requires a strong heat to fuse it. The heat of common furnaces is insufficient to oxidize it ; but the heat of the most powerful burning lenses vitrifies a por- tion of it, and causes it to emit fumes ; which, when received on a plate of gold, are found to be silver in the metallic state. It has like- wise been partly oxidized by twenty successive exposures to the heat of the porcelain furnace at Sevres. By passing a strong electric shock through a silver wire, it may be converted into a black oxide ; and by a powerful galvanic battery, silver leaf may be made to burn with a beautiful green light. Lavoisier oxidized it by the blowpipe and oxygen gas ; and a fine silver wire burns in the kindled united stream of oxygen and hydrogen gases. The air alters it very little, though it is disposed to obtain a thin purple or black coating from the sulphu- rous vapours which are emitted from animal substances, drains, or putrefying matters. This coating, after a long series of years, has been observed to scale off from images of sil- rer exposed in churches ; and was found, on examination, to consist of silver united with sulphur. There seems to be only one oxide of silver, which is formed either by intense ignition in an open vessel, when an olive-coloured glass is obtained ; or by adding a solution of caustic barytes to one of nitrate of silver, and heating the precipitate to dull redness. Sir H. Davy found that 100 of silver combine with 7-3 of oxygen in the above oxide ; and if we sup- pose it to consist of a prime equivalent of each constituent, we shall have 13-7 for the prime of silver. Silver leaf burned by a voltaic bat- tery affords the same olive- coloured oxide. The prime equivalent of silver seems to be 13-75, or 110 on the hydrogen scale. Silver combines with chlorine, when the SIL metal is heated hi contact with the gas. This chloride is, however, usually prepared by add- ing muriatic acid or a muriate, to nitrate of ilver. It has been long known by the name of luna-cornea or horn-silver, because thouj*h a white powder, as it falls down from the nitrate solution, it fuses at a moderate heat, and forms a horny-looking substance when it cools. It consists of 13-75 silver -f- 4-5 chlorine. The sulphuret of silver is a brittle sub- stance, of a black colour and metallic lustre. It is formed by heating to redness thin plates of silver stratified with sulphur. It consists of 13-75 silver + 2 sulphur. Fulminating silver is formed by pouring lime water into the pure nitrate, and filtering, washing the precipitate, and then digesting on it liquid ammonia in a little open capsule. In 12 hours, the ammonia must be cautiously decanted from the black powder, which is to be dried in minute portions, and with extreme circumspection, on bits of filtering paper or card. If struck, in even its moist state, with a hard body, it explodes ; and if in any quan- tity, when dry, the fulmination is tremendous. The decanted ammonia, on being gently heated, effervesces, from disengagement of azote, and small crystals appear in it when it cools. These possess a still more formic ablu power of detonation, and can scarcely bear touching even under the liquid. It seems to be a compound either of oxide of silver and ammonia, or of the oxide and azote. The latter is probably its true constitution, like the explosive iodide and chloride. The sudden extrication of the condensed gas is the cause of the detonation. Silver is soluble in the sulphuric acid when concentrated and boiling, and the metal in a state of division. The muriatic acid does not act upon it, but the nitric acid, if somewhat diluted, dissolves it with great rapidity, and with a plentiful disengagement of nitrous gas; which, during its extrication, gives a blue or green colour to the acid, that entirely disappears if the silver made use of be pure ; if it contain copper, the solution remains greenish ; and if the acid contain either sulphuric or muriatic acid, these combine with a portion of the silver, and form scarcely soluble compounds, which fall to the bottom. If the silver contain gold, this metal separates in blackish-coloured flocks. The nitric acid dissolves more than half its weight of silver; and the solution is very caustic, that is to say, it destroys and corrodes animal substances very powerfully. The solution of silver, when fully saturated, deposits thin crystals as it cools, and also by evaporation. These are called lunar nitre, or nitrate of silver. A gentle heat is sufficient to fuse them, and drive off their water of crys- tallization. In this situation the nitrate, or 3 A SIL SIL rather subnitrate, for the heat drives off part of the acid, is of a black colour, may be cast into small sticks in a mould, and then forms the lapis infernalis, or lunar caustic used in surgery. A stronger heat decomposes nitrate of silver, the acid flying off, and the silver re- maining pure. It is obvious that, for the purpose of forming the lunar caustic, it is not necessary to suffer the salt to crystallize, but that it may be made by evaporating the solu- tion of silver at once to dryness ; and as soon as the salt is fused, and ceases to boil, it may be poured out. The nitric acid driven off from nitrate of silver is decomposed, the products being oxygen and nitrogen. The sulphate of silver, which is formed by pouring sulphuric acid into the nitric solution of silver, is sparingly soluble in water ; and on this account forms crystals, which are so small, that they compose a white powder. The muriatic acid precipitates from nitric acid the saline compound called luna-cornea, or horn-silver ; which has been so distinguished, because, when melted and cooled, it forms a semitransparent and partly flexible mass, re- sembling horn. It is supposed that a prepara- tion of this kind has given rise to the accounts of malleable glass. This effect takes place with aqua regia, which acts strongly on silver but precipitates it in the form of muriate, as fast as it is dissolved. If any salt with base of alkali, containing the muriatic acid, be added to the nitric solu- tion of silver, the same effect takes place by double affinity ; the alkaline base uniting with the nitric acid, and the silver falling down in combination with the muriatic acid. Since the muriatic acid throws down only silver, lead, and mercury, and the latter of these two is not present in silver that has passed cupellation, though a small quantity of copper may elude the scorification in that pro- cess, the silver which may be revived from its muriate is purer than can readily be obtained by any other means. When this salt is ex- posed to a low red heat, its chlorine is not ex- pelled ; and a greater heat causes the whole con- crete either to rise in fumes, or to pass through the pores of the vessel. To reduce it, there- fore, it is necessary that it should be tritu- rated with its own weight of fixed alkali and a little water, and the whole afterwards exposed to heat in a crucible, the bottom of which is covered with soda ; the mass of muriate of silver being likewise covored with the same substance. In this way the acid will be sepa, rated from, the silver, which is Deduced to its metallic state. As the precipitate of muriate of silver is very perceptible, the nitric solution of silver is used as a test of the presence of muriatic acid in waters ; for a drop of this solution poured into such waters will cause a very evident cloudiness. The solution of silver is also used by assayers to purify the nkric acid from any admixture of muriatic acid. In this state they call it precipitated aquafortis. M. Chenevix found, that a chlorate of sil- ver may be formed, by passing a current of chlorine through water in which oxide of sil- ver is suspended ; or by digesting phosphate of silver with hyperoxymuriate of alumina. It requires only two parts of hot water for its solution, and this affords, on cooling, small white, opaque, rhomboidal crystals. It is likewise somewhat soluble in alcohol. Half a grain, mixed with half as much sulphur, and struck or rubbed, detonates with a loud report and a vivid flash. Compounds of silver with other acids are best formed by precipitation from its solution in nitric acid ; either by the acid itself, or by its alkaline salts. Phosphate of silver is a dense white precipitate, insoluble in water, but soluble in an excess of its acid. By heat it fuses into a greenish opaque glass. Car- bonate of silver is a white insoluble powder, which is blackened by light. The fluate and borate are equally soluble. Distilled vinegar readily dissolves the oxide of silver, and the solution affords long white needles, easily crystallized. See SALTS. The precipitates of silver, which are formed , by the addition of alkalis or earths, are all re- ducible by mere heat, without the addition of any combustible substance. A detonating powder has been sold lately at Paris as an object of amusement. It is en- closed between the folds of a card, cut in two lengthwise ; the powder being placed at one end, and the other being notched, that it may be distinguished. If it be taken by the notch- ed end, and the other be held over the flame of a candle, it soon detonates, with a sharp sound, and violent flame. The card is torn, and changed brown ; and the part in contact with the composition is covered with a slight metal- lic coating, of a grayish-white colour. This compound, which M. Descotils calls detonating silver, to distinguish it from the fulminating silver of M. Berthollet, may bo made by dissolving silver in pure nitric acid, and pouring into the solution, while it is going on, a sufficient quantity of rectified al- cohol : or by adding alcohol to a nitric solu- tion of silver with considerable excess of acid. In the first case, the nitric acid into which the silver is put must be heated gently, till the solution commences,, that is, till the first bub- bles begin to appear. Tt is then to be re- moved from the fire, and a sufficient quantity of alcohol to be added immediately, to pre- vent the evolution of any nitrous vapours. The mixture of the two liquors occasions an extrication of heat ; the effervescence quickly recommences, without any nitrous gas being disengaged ; and it gradually increases, emit- ttng at the same time a strong smell of nitric SIL 723 SIL ether. In a short time the liquor becomes added, till the silver is completely covered, turbid, and a very heavy, white, crystalline and all the spaces between the coils filled. A powder falls down, which must be separated cover is then to be luted on, with a small hole when it ceases to increase, and washed several times with small quantities of water. If a very acid solution of silver previously made be employed, it must be heated gently, and the alcohol then added. The heat ex- cited by the mixture, which is to be made gradually, soon occasions a considerable ebul- c ._ e _._ _ r ^. w ^ F u^ lition, and the powder immediately precipi- a cover luted on as before, to prevent the ac- tates - cess of any inflammable matter ; and the cru- It would be superfluous to remind the che- cible exposed to a heat sufficiently strong to mist, that the mixture of alcohol with hot ni- melt the glass very fluid. On cooling and trie acid is liable to occasion accidents, and breaking the crucible, the silver will be found that it is consequently prudent to operate on reduced at the bottom, and perfectly pure. for the escape of the gas ; and after it has been exposed to a heat sufficient to melt silver, for about a quarter of an hour, the whole of the alloy will be oxidized. The contents of this crucible are then to be poured into a larger, into which about three times as much powdered green glass has been previously put ; small quantities. Sulphur combines very easily with silver, This powder has the following properties : if thin plates, imbedded in it, be exposed to a It is white and crystalline ; but the size and heat sufficient to melt the sulphur. The sul- lustre of the crystals are variable. Light phuret is of a deep violet colour, approaching alfa-Ko -.' n I,'*.*!,, U j. _ 1T 1 ' -L1__l_ -.1 3 n .*?.. alters it a little. Heat, a blow, or long con- tinued friction, causes it to inflame with a to black, with a degree of metallic lustre, opaque, brittle, and soft It is more fusible brisk detonation. Pressure alone, if it be not than silver, and this in proportion to the quan- very powerful, has no effect on it. It like- tity of sulphur combined with it. A strong wise detonates by the electric spark. It is heat expels part of the sulph slightly soluble in water. It has a very strong metallic taste. Concentrated sulphuric acid occasions it to take fire, and is thrown by it to a considerable distance. Dilute sulphuric acid appears to decompose it slowly. Process for separating Silver from Copper by Mr. Kelr. Put the pieces of plated metal into an earthen glazed pan ; pour upon them some acid liquor, which may be in the proportion of eight or ten pounds of sulphuric acid to one pound of nitre ; stir them about, that the sur- faces may be frequently exposed to fresh li- quor, and assist the action by a gentle heat from 100 to 200 of Fahrenheit's scale. When the liquor is nearly saturated, the silver is to be precipitated from it by common salt, Sulphuretted hydrogen soon tarnishes the surface of polished silver, and forms on it a thin layer of sulphuret. The alkaline sulphurets combine with it by heat, and form a compound soluble in water. Acids precipitate sulphuret of silver from this solution. Phosphorus left in a nitric solution of silver becomes covered with the metal in a dendritic form. By boiling, this becomes first white, then a light black mass, and is ulti- mately converted into a light brown phos- phuret. The best method of forming a phos- phuret of silver is Pelletier's, which consists in mixing phosphoric acid and charcoal with the metal, and exposing the mixture to heat. Most metallic substances precipitate silver in the metallic state from its solution. The assayers make use of copper to separate the silver from the nitric acid used in the process which forms a muriate of silver, easily re- of parting. The precipitation of silver by ducible by melting it in a crucible with a sufficient quantity of potash ; and lastly, by refining the melted silver, if necessary, with a little nitre thrown upon it. In this manner the silver will be obtained sufficiently pure, and the copper will remain unchanged. Other- wise, the silver may be precipitated in its me- tallic state, by adding to the solution of silver a few of the pieces of copper, and a sufficient quantity of water to enable the liquor to act upon the copper. Mr. Andrew Thomson, of Banchory, has recommended the following method of purify- ing silver, which he observes is equally ap- plicable to gold. The impure silver is to be flatted out to the thinness of a shilling, coiled up spirally, and put into a crucible, the bot- mercury is very slow, and produces a peculiar symmetrical arrangement, called the tree of Diana. In this, as in all precipitations, the peculiar form may be affected by a variety of concomitant circumstances ; for which reason one process usually succeeds better than an- other. Make an amalgam, without heat, of four drachms of leaf silver with two drachms of mercury. Dissolve the amalgam in four ounces or a sufficient quantity of pure nitric acid of a moderate strength ; dilute this solution in about a pound and a half of distilled water ; agitate the mixture, and preserve it for use in a glass bottle with a ground stopper. When this preparation is to be used, the quantity of one ounce is put into a phial, and the size of torn of which is covered with black oxide of a pea of amalgam of gold, or silver, as soft as manganese. More of this oxide is then to be butter, is to be added ; after which the vessel 3 A2 SIL SIL must be left at rest. Soon afterwards, small filaments appear to issue out of the ball of amalgam, which quickly increase, and shoot out branches in the form of shrubs. Silver unites with gold by fusion, and forms a pale alloy, as has been already mentioned in treating of that metal. With platina it forms a hard rm'xture, rather yellower than silver it- self, and of difficult fusion. The two metals do not unite well. Silver melted with one- tenth part of crude platina, from which the ferruginous particles had been separated by a strong magnet, could not be rendered clear of scabrous parts, though it was repeatedly fused, poured out, and laminated between rollers. It was then fused, and suffered to cool in the crucible, but with no better success. After it had been formed, by rolling and hammering, into a spoon for blowpipe experiments, it was exposed to a low red heat, and became rough and blistered over its whole surface. The quantities were one hundred grains of silver, and ten grains of platina. Nitre was added during the fusions. Silver very readily combines with mercury. A very sensible degree of heat is produced when silver leaf and mercury are kneaded to- gether in the palm of the hand. With lead it forms a soft mass, less sonorous than pure silver. With copper it becomes harder and more sonorous, at the same time that it remains sufficiently ductile : this mixture is used in the British coinage. 12i parts of silver, al- loyed with one of copper, form the compound called standard silver. The mixture of silver and iron has been little examined. With tin it forms a compound, which, like that of gold with the same metal, has been said to be brittle, however small the proportion ; though there is probably as little foundation for the assertion in the one case as in the other. With bismuth, arsenic, zinc, and antimony, it forms brittle compounds. It does not unite with nickel. The compound of silver and tungsten, in the proportion of two of the former to one of the latter, was extended under the hammer during a few strokes ; but afterwards split in pieces. See IRON. The uses of silver are well known : it is chiefly applied to the forming of various uten- sils for domestic use, and as the medium of exchange in money. Its disposition to assume a black colour by tarnishing, and its softness, appear to be the chief objection to its use in the construction of graduated instruments for astronomical and other purposes, in which a good white metal would be a desirable acqui- sition. The nitrate of silver, besides its great use as a caustic, has been employed as a me- dicine, it is said with good success, in epileptic cases, in the dose of l-20th of a grain, gra- dually increased to l-8th, three times a-day. D:-. Cappe gave it in a dose of l-4th of a grain three times a-day, and afterwards four times, in what he supposed to be a case of angina pectoris, in a stout man of sisty, whom he cured. He took it for two or three months. Dr. Cappe imagines that it has the eft'ect of increasing the nervous power, by which mus- cular action is excited. The frequent employment in chemical re- searches of nitrate of silver as a reagent for combined chlorine, occasions the production of a considerable quantity of the chloride (muriate) of silver, which is usually reconverted into metal by fusion with potash in a crucible. But, as much of the silver is lost in this way, it is better to expose the following mixture to the requisite heat : Chloride of silver, 100 Dry quicklime, . 19-8 Powdered charcoal, . 4-2 An easier method, however, is to put the metallic chloride into a pot of clean iron or zinc, to cover it with a small quantity of water, and to add a little sulphuric or muri- atic acid. The reduction of the chloride of silver by the zinc or iron is an operation which it is curious to observe, especially with the chloride in mass (luna-cornca). It begins first at the points of contact, and speedily ex- tends in the form of ramifications, over its whole surface, and into its interior. Hence, in less than an hour, considerable pieces of horn-silver are entirely reduced. If the mass operated on be considerable, the temperature rises, and accelerates the revivification. On the small scale, artificial heat may be applied. Ann. de Chimie,July, 1820. See SALTS. SILVERING. There are various methods of giving a covering of silver or silvery aspect to the surfaces of bodies. The application of silver leaf is made in the same way as that of gold, for which see GILDING. Copper may be silvered over by rubbing it with the following powder : Two drachms of tartar, the same quantity of common salt, and half a drachm of alum, are mixed with fifteen or twenty grams of silver precipitated from nitric acid by copper. The surface of the copper becomes white when rubbed with this powder, which may afterward be brushed off' and polished with leather. The saddlers and harness-makers cover their wares with tin for ordinary uses, but a cheap silvering is used for this purpose as follows : Half an ounce of silver that has been precipi- tated from aquafortis by the addition of copper, common salt, and muriate of ammonia, of each two ounces, and one drachm of corrosive muriate of mercury, are triturated together, and made into a paste with water ; with this, copper utensils of every kind, that have been previously boiled with tartar and alum, are rubbed, after which they are made red-hot, and then polished. The intention of this pro- cess appears to be little more than to apply the silver in a state of minute division to the clean surface of the copper, and afterward to fix it there by fusion ; and accordingly this silvering SOA 725 SOA may be effected by using the argentine preci- pitate here mentioned, with borax or mercury, and causing it to adhere by fusion. The dial-plates of clocks, the scales of baro- meters, and other similar articles, are silvered by rubbing upon them a mixture of muriate of silver, sea salt, and tartar, and afterward care- fully washing off the saline matter with water. In this operation, the silver is precipitated from the muriatic acid, which unites with part of the coppery surface. It is not durable, but may be improved by heating the article, and repeating the operation till the covering seems sufficiently thick. The silvering of pins is effected by boiling them with tin filings and tartar. Hollow mirrors or globes are silvered by an amalgam, consisting of one part by weight of bismuth, half a part of lead, the same quan- tity of pure tin, and two parts mercury. The solid metals are to be first fused together, and the mercury added when the mixture is almost cold. A very gentle heat is sufficient to fuse this amalgam. In this state it is poured into a clean glass globe intended to be silvered, by means of a paper funnel, which reaches to the bottom. At a certain temperature, it will stick to the glass, which by a proper motion may thus be silvered completely, and the su- perfluous amalgam poured out. The appear- ance of these toys is varied by using glass of different colours, such as yellow, blue, or green. . SKORODITE. Colour kek- green. Mas- sive, but generally crystallized in very short broad rectangular four-sided prisms. Fracture uneven. Translucent. As hard as calcareous spar. Easily frangible. It melts before the blowpipe, with emission of arsenical vapour, and is converted into a reddish-brown mass, which, when highly heated, so as to drive off all the arsenic, becomes attractible by the magnet. It is an ar&eniate of iron, without copper. It occurs in quartz and hornstone, in primitive rocks, in the Schneeberg mining district in Saxony. SLATE (ADHESIVE). See CLAY. SLATE CLAY. See CLAY. SLATE COAL. See COAL. SLATE SPAR, or SCHIEFER SPAR. A sub-species of limestone. SLICKENSIDES. The specular variety of Galena, so called in Derbyshire. It ex- presses the smoothness of its surface. It occurs lining the walls of very narrow rents. It has a most remarkable property, that when the rock in which it is contained is struck with a hammer, a crackling noise is heard, which is generally folio wed by an explosion of the rock, in the direction and neighbourhood of the vein. The cause of this singular effect has not been satisfactorily explained Jameson. SMALT. See ZAFFRE. SMARAGDITE. Diallage. SMARAGDUS. See EMERALD. SOAP. A compound, in definite pro- portions, of certain principles in oils, fats, or resin, with a salifiable base. When this base is potash or soda, the compound is used as a detergent in washing clothes. When an al- kaline earth, or oxide of a common metal, as litharge, is the salifiable base, the compound is insoluble in water. The first of these com- binations is scarcely applied to any use, if we except that of linseed-oil with lime-water, sometimes prescribed as a liniment against burns ; and the last is known only in surgery as the basis of certain plasters. Concerning the chemical constitution of soaps and saponi- fication, no exact ideas were entertained prior to M. Chevreul's researches ; of which copious details are given under the articles FAT, ELAIN, ACIDS (MAHGARIC and OLEIC). Fats are compounds of a solid and a liquid substance ; the former called stcarine, the latter resembling vegetable oil, and therefore called ela'ine. When fat is treated with a hot ley of potash or soda, the constituents react on one another, so as to generate the solid pearly matter margaric acid, and the fluid matter oleic acid, both of which enter into a species of saline combination with the alkali ; while the third matter that is produced, the sweet principle, remains free. We must therefore regard our common soap as a mixture of an alkaline margarate and oleate, in proportions determined by the relative proportions of the two acids producible from the peculiar species of fat. It is probable, on the other hand, that the soap formed from vegetable oil is chiefly an oleate. No chemical researches have hitherto been made known, on the ompounds of resin with alkalis, though these constitute the brown soaps so extensively manufactured in this country. All oils or fats do not possess in an equal degree the property of saponifica- tion. Those which saponify best, according to D'Arcet, senior, Lelievre, and Pelletier, are, 1. Oil of olives, and of sweet almonds. 2. Animal oils ; as hog's-lard, tallow, but- ter, and horse-oil. 3. Oil of colza, or ri.pe-sced oil. 4. Oil of beech-mast and poppy-seed, when mixed with olive-oil or tallow. 5. The several fish-oils, mingled like the preceding. G. Hempseed-oil. 7- Nut oil and linseed-oil. 8. Palm-oil. J). Rosin. In general, the only soaps employed in commerce, are those of olive-oil, tallow, lard, palm-oil, and rosin. A species of soap can also be formed by the union of bees-wax with alkali ; but this lias no detergent application, being used only for painting in encausto. I shall first describe the fabrication of olive- oil soap : To this oil there is usually added one-fifth of that of rape-seed ; without which addition the section of the soap would not be sufficiently smooth and uniform, but clotty, SOA 726 SOA and unprofitable to the retailer. 100 parts of olive-oil consist, according to Chevreul, of 72 parts of ela'ine, and 28 of stearine ; while 100 parts of rape-seed oil consist of 54 ela'ine, and 46 of stearine. Since, however, the prime equivalents of the margaric and oleic acids, which result from the above two principles, are nearly the same, that of the former being about 34, and of the latter 3C, it does not seem necessary to consider, in a chemical point of view, the proportions of the two oils. Besides the oils, the matters employed in the manufacture of this soap are, 1 st, the soda (barilla) of commerce, of good quality, that is, containing from 30 to 36 per cent, of dry car- bonate ; 2d, quicklime ; 3d, water. 100 parts of oil require about 54 parts of the best barilla for saponification ; and 3 parts of the barilla require 1 of quicklime. After bruising the soda, and slacking the lime, they are mingled, and a certain quantity of cold water is poured upon the mixture. At the end of 12 hours, the liquor is allowed to run off. It is called the first ley, and marks from 20 to 25 on the hydrometer of Baume, (sp. gr. M6 to 1-21). On treating the re- siduum twice with fresh water to exhaust it, two other leys are obtained ; the one from 10 to 15, (sp. gr. 1-072 to 1-114); the other from 4 to 5, (sp. gr. 1-027 to 1-036). When the manufacturer has laid in a stock cf leys, of different densities, he engages in the soap-boiling. For this purpose, he employs boilers (caldrons) which vary much in their construction, and which may contain from 5000 to 2500 pounds of soap. In all cases, they have at their bottom a pipe 2 inches in diameter, called the thorn (epine). They begin by putting weak Icy into the boiler ; they then pour in gradually the oil, and boil the mixture. The combination is soon effected, forming a species of emulsion : they temper the fire, and add successively weak ley and oil, taking care to maintain the mass in a homogeneous pasty state, without ley at the bottom or oil on the surface, in order to accelerate the combination. When they have thus put into the boiler all the oil which they wish to saponify, they add to it slowly some strong ley, which com- pletes the saturation of the oil, converting the emulsion, with an oily excess, into a perfect soap, which separates from the ley, and which collects upon the surface. Whenever this phenomenon occurs, the ley, although very abundant, is no longer fit for saponification ; there is now present in it only some neutral salts, carbonate of soda, and a little caustic soda, unabsorbed. For this rea- son, when the fire has been allowed to fall, they withdraw the ley by the pipe, so as to leave the soap nearly dry. Fresh leys are now added, which are caustic and concentrated ; and the fire is rekindled. Thus there is poured into the boiler more caustic ley than is required to saturate the oil ; the mixture is then boiled, to leave no doubt of the saturation of the oil with alkali ; and the ebullition is stopped when the ley has attained a specific gravity of 1-15 or 1-2. This ley, over which the soap floats, is next withdrawn, like the preceding, and the soap is left dry at the bottom of the boiler. In this state, the soap is of a deep blue colour bordering on black, and contains only 16 per cent, of water. This colour proceeds from a combination of the oil, alumina, and hydrosul- phuret of iron, which is formed during the pasty process, and which dissolves in the soap. The alumina is derived from the furnaces in which the soda is fabricated, and gets dis- solved in it during the lixiviation. The sul- phuretted hydrogen comes from the hydrosul- phuret of soda contained in the ley, and is set at liberty the moment that the paste or glue is made. As to the oxide of iron, it proceeds from the materials employed, or from the hearth of the furnace, or from the plant itself, when native barilla is employed. This oxide of iron is held in solution by the hydrosul- phuret of soda. When the leys do not con- tain enough of oxide of iron to colour the alu- minous soap into a fine blue, they add to the boiling a sufficient quantity of iron, which is done by sprinkling in a solution of copperas, after the pasty operation. At any rate, it ap- pears that the oil unites almost immediately with the alumina and the oxide of iron ; that there thence results a yellowish alumino-fer- ruginous soap, and that it is only by the heat of ebullition that this soap acquires the blue colour. The soap made by the above process may be converted either into white or marbled soap. To convert it into white soap, we must mingle it gradually with dilute leys, with a gentle heat, and allow deposition to take place, with a covered boiler. The blackish alumino- ferruginous soap, not being soluble in the soda-soap at this temperature, separates from it, and falls to the bottom of the boiler. The soap-paste, which has become perfectly white, is now taken out, and run into the wooden frames, where it becomes hard on cooling. From these it is finally removed, and cut into bars. This soap is known in France under the name of soap in tables, (savon en table.) Ac- cording to M. Thenard, it consists of, Soda, 4-6 Fat matter, 50-2 Water, 45-2 100-0 According to M. D'Arcet's analysis, as re- ported to me by M. Clement, Marseilles white soap is composed of, Soda, ""-; ; - 6 Oil, - - ** 60 Water, - - . 34 100 SOA 727 SOA By my experiments on that soap, the quan- tity of soda in it is from 6 to G-5 per cent. This soap is preferred for delicate purposes ; as the washing of lace, and for dyeing ; be- cause, having been edulcorated with very weak leys, and purified by subsidence and. decanta- tion, it contains no excess of alkalTj nor any foreign body. It is hence much smoother and milder than the marbled soap, of which we are now to treat. When the soap-boiling is finished, and when the ley over which it swims has acquired a specific gravity of from 1-15 to 1-20, the soap is of a blackish-blue colour, as we have said above. In this state, if, instead of wishing to make table soap, we desire to make the marbled kind, we pursue the following plan : We have seen that the soap contains then but 16 per cent, of water, and that the entire mass has a dark colour. We must add water to supply the deficiency, in onder that the colouring matters be separated from the white paste, and that it may unite into veins of greater or less size, so as to form a species of blue marbling, in a white basis. The separa- tion of this body may be compared to a species of crystallization. For its proper production, the soap must be suitably diluted, and it must not be allowed to cool either too slowly or too quickly. If it be too much diluted, and if it cool too slowly, we obtain only a white soap, the whole marbling falling to the bottom. In the opposite case, it is entirely in little grains, like a mass of granite. This process is founded, we perceive, on the smaller solubility of the alumino-ferru- ginous soap, at a low temperature ; and on the property which the solution possesses of not being able to retain it, and of separating from it at a certain density. At all events, whenever there is added to the lolling a suitable quantity of weak ley, to bring it to the desired point, this soap is run into the frames in the same way as the white soap, and is taken out after cooling to be cut into bars. The frames or boxes for cooling the soap are either wooden boxes with moveable sides fixed by wedges, or are stone troughs jointed with cement. The platform on which they rest must be so constructed, as to allow the ley to run off into a reservoir. This mottled soap is always harder and more uniform in its proportions tl^an the white table-soap. In fact, the production of the marbling does not permit the manufacturer to vary the quantity of the water; for this depends on the marbling. White table-soap, on the contrary, may receive as much water as the manufacturer shall desire, and it is even whiter the more water it contains. It thence appears, that the marbled soap deserves a preference. Some years ago, I analyzed the foreign Castile soap, as also an imitation of it made in London. The first had a specific gravity of 1-0705. It consisted of, Soda, . 9.0 Well-dried oily matter, . 76-5 Water with a little colouring matter, 14-5 100-0 The specific gravity of the second was only 0-96GJ) ; for it remained at rest in any part of a dilute alcohol of that density. Its com- position was, Soda, ' .'''"" 105 Pasty consistence and fat, 75-2 Water with the colouring matter, 14-3 100-0 The difference of density probably arose partly from a higher specific gravity of the oil, and. partly from the greater chemical con- densation Of the soapy particles in the foreign marbled soap, usually caMed Castile soap by the apothecaries. Both of the above soaps were very dry. Berry's white soap yielded me, Soda, 8 Fatty matter, 75 Water, 17 100 Glasgow best white soap, Soda, 6-4 Tallow, 60-0 Water with a little muriate of soda, 33- C 100-0 Brown or rosin -soap, (Glasgow), Soda, 6-5 Rosin and fat, 70-0 Water, 23-5 100-0 I have since examined several of the com- mon white soaps. The average of soda per cent, is about 5, from which their detergent quality may be inferred to be considerably inferior to the preceding soaps, which were all carefully manufactured. The soap lately imported from India, when freed from the soda powder on its surface, yields less than 5 per cent, of combined soda, and is hence not so powerful a detergent as many of the com- mon soaps of this country. It is, moreover, highly charged with muriate of soda. The composition of a good soft, or potash soap, made by a respectable manufacturer in Glasgow, was as follows : Potash, * 9 Fat, .... 43-7 Water, 47-3 100-0 Here the equivalent proportions are no longer observed. As we may estimate the SOA 728 SOA mean atomic weight of the oleic and margaric acids at 35, or ten times that of lime (oxygen being I), we see that 9 of potash should take 52-5 of fat, instead of 43-?. 6 of soda (equi- valent to 9 of potash) in a hard soap will in- dicate in like manner 52-5 of fat. I consider this proportion to be that of good soap, such as the best Marseilles ; but we shall generally find, I believe, somewhat less than 5 in 100 parts of our soaps of commerce, sometimes only 4-5 ; and hence such soaps may be es- timated at Soda, .... 5-00 or 4-5 Fat, 43-75 39-4 Water and muriate of soda. 51-25 56-1 100-00 100-0 There are debased soaps, however, of which the pretended snow-soap is the most remark- able, that contain far less of the real saponified compound than the above. It is the practice of some persons to keep the soap in strong brine, after it has been charged with a large dose of common salt. Such adulterations should be detected, and their authors exposed. My alkalimeter, noticed in the introduction, will enable any person, however little skilled in chemistry, to ascertain in a few minutes the detergent or washing quality of any soap. The specific gravity of soap is in general greater than that of water. Its taste is faintly alkaline. When subjected to heat, it speedily fuses, swells up, and is then decomposed. Exposed to the air in thin slices, it soon be- comes dry ; but the whole combined water does not leave it, even by careful desiccation on a sandbath. Thus 100 parts of Berry's cake soap, analyzed above, loses only 12 per cent. ; and 100 of the best Glasgow white soap, only 21. If we suppose good hard soap to consist of 1 prime soda, 1 prime saponified fat, and 20 primes water, we shall have its theoretic composition to be Soda, Fat, Water, 4 C-5 35 5G-9 22-5 3G-6 Cl-5 100-0 This is probably the true constitution, which may be occasionally modified by the forma- tion of a little suboleatc or submargarate, and a slight variation in the quantity of water, either from evaporation, or the presence of a little in excess, not chemically combined. When such soap is desiccated, if it still retains 10 atoms of intimately combined water, the proportion of this per cent, will be 22, nearly coinciding with the last of the above results. Soap is much more soluble in hot than in cold water This solution is instantly dis- turbed by the greater number of acids, which seizing the alkali, either separate the fatty principles, or unite with them into an acido- soapy emulsion. The solution is likewise decomposed by almost all the earthy and metallic salts, which give birth to insoluble compounds of the oleic and margaric acids with the salifiable bases. Soap is soluble in alcohol ; and in lage quantity by the aid of heat. When boiling alcohol is saturated with soap, the liquid, on cooling, forms a consistent transparent mass of a yellow colour. When this mass is dried, it still retains its transparency, provided the soap be a compound of tallow and soda ; and in this state it is sold by the perfumers in this country. Good soap possesses the property of re- moving from linen and cloth the greater part of fatty substances which may have been ap- plied to them. With regard to marbled soaps, M. Chaptal, in his Chimie AppUqute, says, that it is not till after two days' boiling, that the process of variegation is begun. With this view y^-g- part of the sulphate of iron, relatively to the oil intended for saponification, is diluted, and decomposed with a weak lixivium. This so- lution (mixture) is then poured into the caldron, which is kept in a state of ebullition till the paste becomes black ; after which the fire is extinguished, and the lixivium which remains unincorporated is drawn off. When this is done, they rekindle the fire, and supply the paste with ley during 24 hours ; after which the fire being put out, the matter is left to settle, and the lixivium drawn off as before. This process is repeated for eight or nine days, at the end of which the fire is removed, and the lixivium evacuated. As soon as the mass has settled, about 12 pounds avoirdupois of Spanish-brown diffused through water are added to it. When this is done, two work- men, stationed on boards set over the caldron, and furnished with long poles, to the extremity of each of which is attached a board about ten inches square, raise up the paste, and agitate it in different directions, while others pour lixivium in at intervals, till the paste be ren- dered fluid. After this operation the soap is removed into the moulds. The description of the marbling process previously given is taken from Thenard, and seems to me more correct, though the above manipulations are no doubt worthy of atten- tion. We ascertain that soap has attained a due degree of consistence, 1. By allowing a small portion of it to fall and coagulate on a slate. 2. If on shaking a spatula, which has been dipped into the paste, briskly in the air, the soap be detached in the form of ribbons, without adhering to the wood. 3. By the peculiar odour of soap, and by handling it between the fingers. At the stage of saponi- fication, when the paste is becoming stiff, and beginning to separate from the aqueous liquor, Messrs. Pelletier, D'Arcet, and Lelievre, advise us, at this period, to throw into the SOA 729 SOA caldron a few pounds of sea-salt, in order to produce a more complete separation ; the paste then assumes a grained form, somewhat resembling spoiled cream ; the ebullition is maintained during two hours, after which the fire is withdrawn, and the agitation discon- tinued.- When a few hours have elapsed, the liquor which has subsided to the bottom of the caldron is drawn off by means of the pipe ; the fire is rekindled, the soap is dissolved by the aid of a little water poured into the caldron, the mixture is agitated, and when it is com- pletely liquefied, and in a boiling state, the remainder of the first ley (about 1-14 sp. gr.) is gradually added to it. In some manufac- tures, says M. Chaptal, the strongest lixivium (the first) is employed at the commencement of the ebullition ; by which method the paste becomes quickly thickened to a considerable degree, and requires to be managed by persons skilled in such operations. It is judged ne- cessary to pour in fresh ley when the paste sinks down, and remains at rest. They con- tinue to employ the strong ley till it be nearly exhausted. Then the boiling subsides, that is, it sinks down, and appears as if stationary. It boils in this quiet manner during three or four hours; after which it is moistened by pouring into it the second lixivium (1-072 to 1-089 sp. gr.), while care is at the same time taken progressively to augment the heat It very rarely happens, when the strongest lix- ivium has been used at the beginning, that the third ley (1-027 to 1-04 sp. grav.) is ne- cessary. This is employed only when the paste does not boil, because then the object is to dilute it. As soon as the boiling is finished, the fire is withdrawn ; the lixivium is then drawn off; after which the paste is left to cool, and taken up before it be fully coagulated, by means of copper, or wooden buckets, to be transferred into moulds, into the bottoms of which a portion of pulverized lime has been previously introduced, to pre- vent the soap from adhering to them. At the end of two or three days, when the soap has become sufficiently hard, they remove it from the mould, and divide it into wedges of dif- ferent sizes by means of a brass wire. They place these wedges on a floor edgeways, where they are allowed to remain till they become perfectly firm and dry. The fair trader, adds M. Chaptal, lays his account with procuring five pounds of soap from three pounds of oil. The soap is not marketable till it ceases to receive any im- pression from the fingers. It must not be supposed that the lixivium employed at the commencement of the process should be constantly continued. The great art of soap-making consists in knowing to determine, from the appearance of the paste and other circumstances, what kind of lixivium should be employed during each step of the operation. The overseers regulate their conduct in this respect by observation and experience. The form and size of the bubbles, the colour of the paste, the volume of that which is thrown out on the edges of the vessel, the consistence of the matter, and its disposition to swell, as well as the appearance of the steam, all furnish them with criteria by which to regulate their conduct. It sometimes happens, that the paste, though apparently very firm, yet when set in the cold air to concrete, throws out much water, and is resolved into small grains pos- sessing little consistency. In this case it is evident that the ley is in excess, and must be dissipated by heat, or precipitated (separated) by means of marine salt. Frequently, also, the paste becomes greasy, and the oil appears to separate from the soda. As this in general proceeds from the paste not being imbued with sufficient water to keep it in combina- tion, it is necessary to add to it a portion of water, or very weak lixivium, to remedy this defect. The adulterations most commonly practised on soap are the following : When the soap is made, they add to it much water, which renders it white. Fre- quently pulverized lime, gypsum, or pipe- clay are incorporated with it The former of these frauds is readily discovered by the rapid loss of weight which the soap suffers on exposure to a dry air; the second can be easily detected by solution in alcohol, when the earthy matters fall down. Hard soap is made in Scotland chiefly with kelp and tallow. That crude alkali rarely contains more than from one to five per cent, of free soda, mixed with some sulphate and hydrosulphite, and nearly 33 per cent, of muriate of soda. To every ton of kelp broken into small fragments, about l-6th of new slacked lime is added. The whole, after mixture, are put into a large tub called a cave, having a perforation at the bottom, shut with a wooden plug. Upon the materials, water is very slowly poured. The liquid, after digestion, is suffered to run slowly off into a reservoir sunk in the ground. The first portion, or ley No. 1. is of course the strongest, and is reserved for the last operation in soap- boiling. I find that a gallon of that of average strength contains 1000 grains of real soda, so that one pound of the alkali is present in seven gallons of the ley. The second portion run off contains 800 grains in 1 gallon, equivalent to a pound in 8| gallons. The third contains 600 grains per gallon, or 1 pound in Ilf gallons ; and the fourth, 200 grains, or 1 pound in 35 gallons. The last is not em- ployed directly, but is thrown on a fresh mix- ture in the cave, to acquire more alkaline strength. Six days are required to make one boiling of soap, in which two tons or upwards of tal- low may be employed. The leys, 2. and 3. SOA 730 SOA mixed, are used at the beginning, diluted with water, on account of the excess of sea-salt in the kelp. A quantity of ley, not well defined, is poured on the melted tallow, and the mix- ture is boiled, a workman agitating the ma- terials to facilitate the combination. The fire being withdrawn, and the aqueous liquid having subsided, it is pumped off, and a new portion is thrown in. A second boil is given, and so on in succession. 2 or 3 boils are performed every 12 hours, for 6 days, con- stituting 12 or 18 operations in whole. Towards the last, the stronger ley is brought into play. Whenever the workman perceives the saponification perfect, the process is stopped ; and the soap is lifted out, and put into the moulds. When the price of American potash is such as to admit of its economical employment, a ley of that alkali, rendered caustic by lime, is used in the saponification, and the soft potash soap which results is converted into a hard soda soap, by double decomposition. This is effected either by the addition of common salt, or rather of a kelp ley; which supplies abundance of muriate of soda. The muriatic acid goes to the potash, to constitute muriate of potash, which dissolves in the water, and is drawn off in the spent ley ; while the soda enters into combination with the fat, (or rather the margaric and oleic acids, now evolved), and forms a soap, which becomes solid on cooling. A weak potash ley is used at first, and subsequently one of greater strength. I have found the potash ley of a respectable manufacturer to contain 3000 grains of real potash per gallon; which is equivalent to 1 pound of real alkali in 2 gallons. But I cannot offer this proportion as any standard ; for practical soap-boiling is, in regard to the alkaline strength of the leys, in a deplorable state of darkness and imper- fection. To this cause chiefly we may ascribe the perpetual disappointments which occur in the soap manufactories. Two tons of tallow, properly saponified, should yield fully 3 tons of marketable white soap. But I have known a manufacturer produce only 2^ tons, by some ridiculous mismanagement of his leys. The sulphuretted hydrogen present in the crude alkalis, gives a blue stain to the soap. This may be removed, in a great measure, by contact of air. But the proper plan would be, to employ an alkali previously deprived as much as possible of its sulphur. Those who decompose sulphate of soda, with the view of using the alkali in saponification, are liable to many accidents from the above cause. Much balsam of sul- phur is formed, at the expense of the soap ; and the manufactured article is generally inferior in detergent powers to the kelp soap, which, however, is by no means so free from sulphur as it might be made, previous to its employment, by simple methods, would at the same time double its alkaline powers. For brown or yellow soap, a mixture of tallow and rosin, with a little palm oil to improve the colour, is used. Soap of the coarser quality is made with equal parts of rosin and tallow. But that of better quality requires 3 parts of tallow to 1 of rosin ; and for every ton of that mixture, half a hundred weight of palm oil. The rosin soaps consume less alkaline ley than those with fat alone. Soft Soaps. The compounds of fats or oils with potash remain soft, or at least pasty. Three kinds of these are known in commerce ; the soaps from rape-seed, and other oleaginous seeds, called green soaps ; toilette soaps, made with hog's lard ; and common soft soaps, made with fish oils. Manufacturers of green soap prepare their potash leys as those of hard soap do their soda leys, and conduct their operations in the same manner till the whole oils be added. In this state the soap resembles an unguent. It contain excess of oil, is white, and hardly transparent. After tempering the fire, they keep stirring continually the bottom of the caldron with large spatulas; they then adci, by degrees, new leys perfectly caustic, and somewhat stronger than the first. The satura- tion of the oil is thus effected, and the soap becomes transparent. The fire is now con- tinued to give the soap a suitable consistency, after which it is run off into barrels to be offered for sale. We perceive that this species of soap differs considerably from the soap manufactured with olive oil and soda. Here, from the com- mencement of the operation to its end, the art of the soap-boiler consists in effecting the com- bination of the oil with the potash, without the soap ceasing to be dissolved in the ley ; whilst in the fabrication of hard soap it is necessary, on the contrary, as we have seen, to separate the soap from the ley, even before the saturation of the oil is accomplished. Green soap contains, in general, more alkali than is absolutely necessary for the saturation of the oil. It is, in fact, a perfect soap, dissolved in an alkaline ley. It should be transparent, of a fine green colour; a shade sometimes produced by means of indigo. According to M. Thenard, it is usually com- posed of Potash, *** 9.5 Fatty matter, - 44.0 Water, ***** 46.5 100.0 This soft soap may be readily converted into hard soap, as we have stated above, by the addition of muriate of soda. Toilette soaps, made with hog's lard and potash, should have as small an alkaline excess as possible. The finer soaps for the toilette are made with oil of sweet almonds, with nut SOA 731 SOD oil, palm oil, suet, or butter. They are either potash or soda soaps, as they may be preferred in the pasty or solid state. The following facts from Chaptal, on soft soaps, are worthy of insertion. After intro- ducing into the caldron the half of the oil intended for one coction, the fire is kindled, and when the oil begins to grow hot, we add to it a portion of the potash lixivium. The remainder of the oil and lixivium must after- wards be gradually poured in during the ebullition. If too much of the lixivium be employed at the commencement, no combi- nation takes place; if the lixivium be too strong, the mixture separates into clots; and if it be too weak, the union is incomplete. The quantity of the ley employed in one coction ought to be in the proportion of 4 parts to 3 of oil. 200 parts of oil, and 125 of potash, yield 325 of soap. When the union is fully accomplished, and the liquor rendered transparent, nothing remains but to employ the necessary degree of coction. The soap- boilers judge of the degree of coction by the consistency, by the colour, and from the time which the soap takes to coagulate. In order to make the froth subside, and render the mass fit for barrelling, one ton of soap (ready made?) is emptied into the caldron. The soap held in the greatest request is of a brown colour, inclining to black. The manufac- turers in Flanders dye the soap, by throwing into the caldron, half an hour before the ter- mination of the boiling or coction, a compo- sition of one pound of the sulphate of iron, half a pound of galls, and an equal quantity of red wood ; and boiling it with the lixivium. When the soap is prepared with a great portion of warm or yellow oi/, a green colour may be imparted to it, by pouring into the ley a solution of indigo. This soap is reckoned of the best quality : it remains always in the state of a soft paste, on which account it is placed in casks as expeditiously as possible. Since writing the above, I have learned the following particulars on the manufacture of soft soap, from an eminent soap-boiler, near Glasgow : 273 gallons of whale or cod oil, and 4 cwt. of tallow, are put into the boiler, with 252 gallons of potash ley, whose alkaline strength I find to be such, that one gallon contains 6COO grains of real potash. Heat is applied, when the mixture froths up very much, but is pre- vented from boiling over by the wooden crib, which surmounts the iron caldron. If it now subside into a doughy magma, the ley has been too concentrated. It should have a thin gluey aspect. There are next poured in, two measures of a stronger ley, holding each 21 gallons, (containing per gallon 8700 gr. real potash), and after a little interval other two measures, and so on progressively, till 14 measures have been added in whole. After suitable boiling, without agitation, the soap is formed, amounting in all to 100 firkins of 64 Ibs. each, from the above quantity of materials. The manufacture of soft soap is reckoned more difficult and delicate than that of hard soap. Rape oil forms a hard soap, neither so consistent nor so white as that from olive oiL Hempseed oil produces a. green- coloured soap, reducible to a paste by a small portion of water. The soaps prepared with oils procured from beech-mast and clove July- flowers, are of a clammy glutinous consistence, and generally of a grayish- colour. Nut oil forms a soap not proper for the hands ; it is of a yellowish-white colour, of a moderate degree of consistence, unctuous, gluey, and continues so on exposure to the air. The soap of which linseed oil forms a constituent part is at first white, but changes to yellow in a short time on exposure to the air. It possesses a strong odour, is unctuous, clammy, glutinous, does not dry in the air, and softens with a very small quantity of water. From what has been said we may conclude, that the soaps prepared with desiccative oils are of a very indifferent quality, that they remain always glutinous, and readily change their colour on exposure to the atmosphere. Some of the volatile oils are not less susceptible of entering into com- binations with the alkalis ; but as such soaps are not employed in the arts, we shall not enter into any description of these saponaceous compounds. SOAP-STONE. See STEATITE. SODA. Formerly called the mineral alkali, because under the name of natron it is found native in mineral seams or crusts. The impure commercial substance called ba- rilla is the incinerated salsola soda. Kelp, the incinerated sea- weed, is a still coarser article, containing seldom above from 2 to 5 per cent, of real soda, while barilla occasionally contains 20. The crystallized carbonate of soda of commerce is procured from the de- composition of sulphate of soda, or muriate of soda. The former is effected by calcination with charcoal and chalk in a reverberatory furnace; the latter is accomplished by the addition of carbonate of potash. To procure pure soda, we must boil a solution of the pure carbonate with half its weight of quicklime, and after subsidence decant the clear ley, and evaporate in a clean iron or silver vessel, till the liquid flows quietly like oil. It must then be poured out on a polished iron plate. It concretes into a hard white cake, which is to be immediately broken in pieces, and put up, while still hot, in a phial, which must be well corked. If the carbonate of soda be some- what impure, then, after the action of lime, and subsequent concentration of the ley, alcohol must be digested on it, which will dissolve only the caustic pure soda, and leave the heterogeneous salts. By distilling off the SOD 732 SOD alcohol in a silver alembic, the alkali may then be obtained pure. This white solid substance is, however, not absolute soda, but a hydrate, consisting of about 100 soda -f 28 water ; or of nearly 77 -f 23, in 100. If a piece of this soda be exposed to the air, it softens and becomes pasty ; but it never deliquesces into an oily- looking liquid, as potash does. The soda in fact soon becomes drier, because by absorption of carbonic acid from the air it passes into an efflorescent carbonate. Soda is distinguishable from potash by sulphuric acid, which forms a very soluble salt with the former, and a sparingly soluble one with the latter; by muriate of platina and tartaric acid, which occasion precipitates with potash salts, but not with those of soda. The basis of soda is a peculiar metal, called sodium, discovered by Sir H. Davy in ,1807, a few days after he discovered potas- sium. It may be procured in exactly the same manner as potassium, by electrical or chemical decomposition of the pure hydrate. A rather higher degree of heat, and greater voltaic power, are required to decompose soda than potash. Sodium resembles potassium in many of its characters. It is as white as silver, possesses great lustre, and is a good conductor of electricity. It enters into fusion at about 200 Fahr., and rises in vapour at a strong red heat. Its sp. gr. is, according to MM. Gay Lussac and Thenard, 0.972, at the temperature of 59 Fahr. In the cold, it exercises scarcely any action on dry air, or oxygen. But when heated strongly in oxygen or chlorine, it burns with great brilliancy. When thrown upon water, it effervesces violently, but does not inflame, swims on the surface, gradually diminishes with great agi- tation, and renders the water a solution of soda. It acts upon most substances in a manner similar to potassium, but with less energy. It tarnishes in the air, but more slowly ; and, like potassium, it is best pre- served under naphtha. Sodium forms two distinct combinations with oxygen ; one is pure soda, whose hydrate is above described; the other is the orange oxide of sodium, observed, like the preceding oxide, first by Sir H. Davy in 1807, but of which the true nature was pointed out, in 1810, by MM. Gay Lussac and Thenard. Pure soda may be formed by burning sodium in a quantity of air, containing no more oxygen than is sufficient for its con- version into this alkali ; i. e. the metal must be in excess : a strong degree of heat must be employed. Pure soda is of a gray colour, it is a non- conductor of electricity, of a vitreous fracture, and requires a strong red heat for its fusion. When a little water is added to it, there is a violent action between the two bodies ; the soda becomes white, crystalline in its appear- ance, and much more fusible and volatile. It is then the substance commonly called pure or caustic soda ; but properly styled the hydrate. . The other oxide or peroxide of sodium may be formed by burning sodium in oxygen in excess. It is of a deep orange colour, very fusible, and a non-conductor of electricity. When acted on by water, it gives off oxygen, and the water becomes a solution of soda. It deflagrates when strongly heated with com- bustible bodies. The proportions of oxygen in soda, and in the orange peroxide of sodium, are easily learned by the action of sodium on water and on oxygen. If a given weight of sodium, in a little glass tube, be thrown by means of the finger under a graduated inverted jar filled with water, the quantity of hydrogen evolved will indicate the quantity of oxygen combined with the metal to form soda ; and when so- dium is slowly burned in a tray of platina, (lined with dry common salt), in oxygen in great excess, from the quantity of oxygen ab- sorbed the composition of the peroxide may be learned. From Sir H. Davy's experiments compared with those of MM. Gay Lussac and Thenard, it appears that the prime equivalent of sodium is 3-0, and that of dry soda, or protoxide of sodium, 4-0; while the orange oxide or deutoxide is 5-0. The numbers given by M. Thenard are, for the first, 100 metal + 33-995 oxygen ; and for the second, 100 metal -f G7-990 oxygen. Another oxide is described containing less oxygen than soda ; it is therefore a sub-oxide. When sodium is kept for some time in a small quantity of moist air, or when sodium in ex- cess is heated with hydrate of soda, a dark grayish substance is formed, more inflam- mable than sodium, and which affords hy- drogen by its action upon water. Only one combination of sodium and chlo- rine is known. This is the important sub- stance common salt. It may be formed directly by combustion, or by decomposing any com- pound of chlorine by sodium. Its properties are well known, and are already described under ACID (MURIATIC). It is a non-con- ductor of electricity, is fusible at a strong red heat, is volatile at a white heat, and crystal- lizes in cubes. Sodium has a much stronger attraction for chlorine than for oxygen ; and soda, or its hydrate, is decomposed by chlo- rine, oxygen being expelled from the first, and oxygen and water from the second. Potassium has a stronger attraction for chlorine than sodium has ; and one mode of procuring sodium easily, is by heating together to redness common salt and potassium. This chloride of sodium, improperly called the mu- riate, consists of 4-5 chlorine + 3-0 sodium. There is no known action between sodium and hydrogen or azote. SOI SOI Sodium combines readily with sulphur and with phosphorus, presenting similar pheno- mena to those presented by potassium. The sulphurets and phosphurets of sodium agree in their general properties with those of potas- sium, except that they are rather less inflam- mable. They form, by burning, acidulous compounds of sulphuric and phosphoric acid and soda. Potassium and sodium combine with great facility, and fonn peculiar compounds, which differ in then* properties, according to the pro- portions of the constituents. By a small quan- tity of sodium, potassium is rendered fluid at common temperatures, and its sp. gr. is con- siderably diminished. Eight parts of potas- sium, and one of sodium, form a compound that swims in naphtha, and that is fluid at the common temperature of the air. Three parts of sodium, and one of potassium, make a compound fluid at common temperatures. A little potassium destroys the ductility of sodium, and renders it very brittle and soft. Since the prime of potassium is to that of sodium as 5 to 3, it will require the former quantity of potassium to eliminate the latter quantity of sodium from the chloride. The attractions of potassium, for all substances that have been examined, are stronger than those of sodium. Soda is the basis of common salt, of plate and crown-glass, and of all hard soaps. Ele- ments of Chemical Phil. SODAL1TE. Colour green. Massive and crystallized in rhomboidal dodecahedrons. Shining. Cleavage double. Fracture small conchoidal. Translucent. As hard as fel- spar. Brittle. Sp. gr. 2-378. It is infu- sible ; becoming only dark gray before the blowpipe. Its constituents are, silica 38-5 or 36, alumina 27-48 or 32, lime 2-7 or 0, oxide of iron 1 or 0-25, soda 25-5 or 25, muriatic acid 3 or 6-75 ; volatile matter 2-10 or 0, loss 1-7 or 0. Thomson and Ekeberg. It was discovered in West Greenland by Sir Charles Gieseke, in a bed in mica slate. SODIUM. See SODA. SOIL. The soil or earth in which vege- tables grow, varies considerably in its com- position, or in the proportions of the different earths of which it consists ; and some plants are found to thrive best in one kind of soil, others in another. Under Analysis, the me- thods of analyzing soils, so as to ascertain their composition, will be found, as given by Sir H. Davy; and we shall here subjoin the rules he has laid down for their improvement, as connected with the principles of which they consist. In cases where a barren soil is examined with a view to its improvement, it ought in all cases, if possible, to be compared with an extremely fertile soil in the same neighbour- hood, and in a similar situation : the differ- ence given by their analyses would indicate the methods of cultivation, and thus the plan of improvement would be founded upon ac- curate scientific principles. If the fertile soil contained a large quantity of sand, in proportion to the barren soil, the process of melioration would depend simply upon a supply of this substance; and the method would be equally simple with regard to soils deficient in clay or calcareous matter. In the application of clay, sand, loam, marie, or chalk, to lands, there are no parti- cular chemical principles to be observed ; but when quicklime is used, great care must be taken, that it is not obtained from the mag- nesian limestone ; for in this case, as has been shown by Mr. Tennant, it is exceedingly in- jurious to land. The magnesian limestone may be distinguished from the common lime- stone by its greater hardness, and by the length of time that it requires for its solution in acids ; and it may be analyzed by the process for car- bonate of lime and magnesia. When the analytical comparison indicates an excess of vegetable matter as the cause of sterility, it may be destroyed by much pul- verization and exposure to air, by paring and burning, or the agency of lately made quick- lime. And the defect of animal and vegetable matter must be supplied by animal or vegetable manure. 1 The general indications of fertility and bar- renness, as found by chemical experiments, must necessarily differ in different climates, and under different circumstances. The power of soils to absorb moisture, a principle essen- tial to their productiveness, ought to be much greater in warm and dry countries than in cold and moist ones ; and the quantity of fine alu- minous earth they contain should be larger. Soils likewise that are situate on declivities ought to be more absorbent than those in the same climate on plains or in valleys. The productiveness of soils must likewise be influenced by the nature of the sub-soil, or the earthy or stony strata on which they rest ; and this circumstance ought to be particularly attended to, in considering their chemical na- ture, and the system of improvement Thus a sandy soil may owe its fertility to the power of the sub-soil to retain water ; and an ab- sorbent clayey soil may occasionally be pre- vented from being barren, in a moist climate, by the influence of a sub-stratum of sand or gravel. Those soils that are most productive of corn, contain always certain proportions of aluminous or calcareous earth in a finely divided state, and a certain quantity of vegetable or animal matter. The quantity of calcareous earth is however very various, and in some cases exceeding small. A very fertile corn soil from Ormiston in East Lothian afforded in a hundred parts only eleven parts of mild calcareous earth ; the finely divided clay amounted to forty-five SOI 734 SOL parts. It lost nine fn decomposed animal and vegetable matter, and four in water, and ex- hibited indications of a small quantity of phos- phate of lime. This soil was of a very fine texture, and contained very few stones or vegetable fibres. It is not unlikely, that its fertility was in some measure connected with the phosphate; for this substance is found in wheat, oats, and barley, and may be a part of their food. A soil from the low lands of Somersetshire, celebrated for producing excellent crops of wheat and beans without manure, I found to consist of one-ninth of sand, chiefly siliceous, and eight-ninths of calcareous marie tinged with iron, and containing about five parts in the hundred of vegetable matter. I could not detect in it any phosphate or sulphate of lime, so that its fertility must have depended prin- cipally upon its power of attracting principles of vegetable nourishment from water and the atmosphere. Mr. Tillet, in some experiments made on the composition of soils at Paris, found, that a soil composed of three-eighths of clay, two- eighths of river sand, and three-eighths of the parings of limestone, was very proper for wheat. In general, bulbous roots require a soil much more sandy, and less absorbent, than the grasses. A very good potato soil, from Varsel in Cornwall, afforded seven-eighths of siliceous sand ; and its absorbent power was so small, that 100 parts lost only 2 by drying at 400 Fahrenheit. Plants and trees, the roots of which are fibrous and hard, and capable of penetrating deep into the earth, will vegetate to advantage in almost all common soils that are moderately dry, and do not contain a very great excess of vegetable matter. The soil taken from a field at Sheffield- place in Sussex, remarkable for producing flourishing oaks, was found to consist of six parts of sand, and one part of clay and finely divided matter. And 100 parts of the entire soil submitted to analysis, produced water 3, silex 54, alumina 28, carbonate of lime 3, oxide of iron 5, decomposing vegetable matter 4, loss 3. From the great difference of the causes that influence the productiveness of lands, it is ob- vious, that in the present state of science, no certain system can be devised for their im- provement, independent of experiment; but there are few cases, in which the labour of analytical trials will not be amply repaid by the certainty with which they denote the best methods of melioration ; and this will parti- cularly happen, when the defect of compo- sition is found in the proportions of the pri- mitive earths. In supplying animal or vegetable manure, a temporary food only is provided for plants, which is in all cases exhausted by means of a certain number of crops ; but when a soil is rendered of the best possible constitution and texture with regard to its earthy parts, its fertility may be considered as permanently established. It becomes capable of attracting a very large portion of vegetable nourish- ment from the atmosphere, and of producing its crops with comparatively little labour and expense. SOLANINE. A substance which M. Baup thinks he has extracted from potatoes. Nothing is known about it. SOLDERS, and SOLDERING. Solders consist merely of simple or mixed metals, by which alone metallic bodies can be firmly united with each other. In this respect it is a general rule, that the solder should always be easier of fusion than the metal intended to be soldered by it ; next to this, care must also be taken, that the solder be as far as is pos- sible of the same colour with the metal that is to be soldered. For the simple solders, each of the metals may be used, according to the nature of that which is to be soldered. For fine steel, copper, and brass work, gold and silver may be em- ployed. In the large way, however, iron is soldered with copper, and copper and brass with tin. The most usual solders are the compound, which are distinguished into two principal classes, viz. hard and soft solders. The hard solders are ductile, will bear hammering, and are commonly prepared of the same metal with that which is to be soldered, with the addition of some other, by which a greater degree of fusibility is obtained, though the addition is not always required to be itself easier of fusion. Undej this head comes the hard solder for gold, which is prepared from gold and silver, or gold and copper, or gold, silver, and copper. The hard solder for silver is prepared from equal parts of silver and brass, but made easier of fusion by the admixture of a sixteenth part of zinc. The hard solder for brass is obtained from brass mixed with a sixth, or an eighth, or even one-half of zinc, which may also be used for the hard solder of copper. It is sold in the shops in a granulated form, under the name of spelter-solder. The soft solders melt easily, but are partly brittle, and therefore cannot be hammered. Of this kind are the following mixtures : Tin and lead in equal parts; of still easier fusion is that consisting of bismuth, tin, and lead, equal parts ; one or two parts of bismuth of tin and lead, each one part In the operation of soldering, the surfaces of the metal intended to be joined must be made very clean, and applied to each other. It is usual to secure them by a ligature of iron wire, or other similar contrivance. The solder is laid upon the joint, together with sal ammoniac or borax, or common glass, accord- ing to the degree of heat intended. These SPA 735 SPE additions defend the metal from oxidation. Glaziers use resin ; and pitch is sometimes employed. Tin-foil applied between the joints of fine brass work, first wetted with a strong solution of sal ammoniac, makes an excellent juncture, care being taken to avoid too much heat. SOLIDS AND SOLIDITY. See CA- LORIC, and CRYSTALLIZATION. SOLUTION. See SALT, CRYSTALLI- ZATION, and ATTRACTION. SOMMITE. NEPHELINE. SOMERVILLITE. A new mineral from Vesuvius. Primary form a right square prism. Colour dull yellow ; occurring in cavities with crystallized black mica. It decrepitates at the blowpipe. SOOT of Wood. An analysis of it is given in the Annales de Chim. et Phys. xxxi. 52, by M. Braconnot. Its constituents are, 1. Ulmin, like that produced arti- ficially from sawdust and pot- ash, estimated at " 30-20 2. Animalized matter, soluble in water, insoluble in alcohol 20-00 3. Carbonate of lime, with traces of carb. of magnesia 14-66' 4. Water . . 12-50 5. Acetate of lime '-- -' - : ' -' 5-65 6. Sulphate of lime 5-00 7. Acetate of potash 4-10 8. Carbonaceous matter insoluble in alkalis -^(i '' 3-85 9. Ferruginous phosphate of lime 1-60 10. Silica V- : ' .' 0-95 11. Acetate of magnesia 0-53 12. Peculiar bitter principle (asbo. line) about , .-, *. 0-50 13. Chloride of potassium - . 0-36 14. Acetate of ammonia, estimated at 0-20 15. Acetate of iron, a trace 100-00 A watery infusion of soot is eminently anti- septic, according to M. Braconnot, and may be used for preserving animal matters from decomposition. SORBATES. Compounds of sorbic, or mallic acid, with the salifiablc bases. See ACID (SORBIC). SORY. The ancient name of sulphate of iron. SPAR (FLUOR). See FLUOR. SPAR (PONDEROUS). See HEAVY SrAR. SPARRY ANHYDRITE, OR CUBE- SPAR. A sub-species of prismatic gypsum. Colour white, passing into blue or red. Mas- sive, in distinct concretions, and crystallized. The primitive figure is an oblique prism, in which the angles are 108 8' and 79 56'. The secondary forms are, a rectangular four- sided prism, a broad six-sided prism, an eight- sided prism, and a broad rectangular four- sided prism, acuminated. Splendent, pearly. Cleavage threefold. Fragments cubical. Frac- ture conchoidal. Transparent. Refracts double. Scratches calcareous spar, but not fluor. Brit- tle. Sp. gr. 2-7 to 3-0. It does not exfoliate before the blowpipe, and melt like gypsum, but becomes glazed over with a white friable enamel. Its constituents are, lime 41-75, sul- phuric acid 55, muriate of soda 1. Klaproth. It is sometimes met with in the gypsum of Nottinghamshire. It occurs in the salt mines of Halle, &c. SPARRY IRON. Carbonate of iron. Colour pale yellowish-gray. Massive, dis- seminated, and crystallized. The primitive form is a rhomboid of 107. The following are some of the secondary forms. The pri- mitive, perfect, or truncated; a still flatter rhomboid ; the spherical lenticular form ; the saddle-shaped lens, and the equiangular six- sided prism. Glistening, or splendent, or pearly. Cleavage threefold. Fracture foliated, or splintery. Translucent on the edges. Streak white or yellowish-brown. Harder than cal- careous spar. Easily frangible. Sp. gr. 3-6 to 3-9. It blackens and becomes magnetic before the blowpipe, but does not melt; it effervesces with muriatic acid. Its consti- tuents are, oxide of iron 57-5, carbonic acid 36, oxide of manganese 35, lime 1-25. Klaproth. It occurs in veins in granite, gneiss, &c. associated with ores of lead, cobalt, silver, copper, &c. But the most extensive forma- tions of this mineral are in limestone. It is found in small quantities in England, Scot- land, and Ireland ; in Saxony, Bohemia, &c. ; and in large quantities in Fichtelgebirge ; and at Schmalkalden in Hessia. It affords an iron well suited for conversion into steel. Jame- son. SPECIFIC GRAVITY is the density of the matter of which any body is composed, compared to the density of another body, assumed as the standard. This standard is pure distilled water, at the temperature of 60 F. To determine the specific gravity of a solid, we weigh it, first in air, and then in water. In the latter case it loses, of its weight, a quantity precisely equal to the weight of its own bulk of water; and hence, by comparing this weight with its total weight, we find its specific gravity. The rule therefore is, Divide the total weight by the loss of weight in water, the quotient is the specific gravity. If it be a liquid or a gas, we weigh it in a glass or other vessel of known capacity ; and dividing that weight by the weight of the same bulk of water, the quotient is, as before, the specific gravity. See HYDROMETER, for another modification of the same rule. To calculate the mean specific gravity of a compound from those of its components, is a problem of perpetual recurrence in chemistry. It is- only , by a comparison of the result of that calculation, with the specific gravity of the compound experimentally ascertained, that we SPE 736 SPE can discover whether the combination has been accompanied with expansion or condensation of volume. As several respectable experi- mental chemists (see ALLOY and AMMONIA) seem deficient in this part of chemical com- putation, I shall here insert a short abstract of a paper which I published on this subject in the fth number of the Journal of Science. The specific gravity of one body is to that of another, as the weight of the first, divided by its volume, is to the weight of the second, divided by its volume ; and the mean specific gravity of the two is found, by dividing the sum of the weights by the sum of the volumes. Let W, , be the two weights ; V, u, the two volumes ; P, being the specific gravities of the two com- ponents. we have P := and p =. ; V v whence V = In the condition when W = to = 1, we have J_ P p then V = J_, v _, and, consequently P+P _ P+p. This value being constantly negative proves that the true .value of the specific gravity \V I fa of the mixture, represented by _ 21 _ , V -j- v is always smaller than the false value, 2\V Example of the last formula : Gold and silver, I2i2! = 14-0 - 2 false or arithmetical mean specific gravity. (P_^)a _ (19.3-10.5)* (8-8)" _ 77-44 P+~p~ ~ ~29lT~ -29~8~29~8 2-6 2A; and A == 1-3, which being subtracted from the arithmetical mean 14-9, leaves 13-6 for the true mean sp. gr. as directly obtained by the formula 151L^1Z? . Pv+pW Sulphuric Acid Table, showing the erroneous Results of the Common Method. See ALLOY. Acid in 100. Arithm. mean density. Experi- mental density. Apparent volume. Aeid in 100. Arith. mean density. Experi- mental density. Apparent volume. 100 90 80 70 60 1-7632 1-6784 1-5936 1-5088 8480 8115 -7120 5975 -4860 100 97-3 98-0 99-7 101-5 50 40 30 20 10 1-4240 1-3392 1-2544 1-1696 1-0848 1-3884 1-2999 12184 1-1410 1-0680 102-6 103-02 102-95 10250 101-57 SPI 737 SPI SPECULAR IRON ORE. See ORES OF IRON. SPECULUM. Mr. Edwards affirms, that different kinds of copper require different doses of tin to produce the most perfect whiteness. If the dose of tin be too small, which is the fault most easily remedied, the composition will be yellowish; if it be too great, the composition will be of a gray-blue colour, and dull appearance. He casts the speculum in sand, with the face downwards ; takes it out while red-hot, and places it in hot wood ashes to cool ; without which precaution it would break in cooling. Mr. Little recommends the following pro- portions : 32 parts of the best bar copper, 4 parts of the brass of pin-wire, 16^ of tin, and 1^ of arsenic. Silver he rejects, as it has an extraordinary effect of softening the metal ; and he found that the compound was not susceptible of the highest polish, unless it was extremely brittle. He first melts the brass, and adds to it about an equal weight of tin. When this mixture is cold, he puts it into the copper, previously fused with black flux, adds next the remainder of the tin, and lastly the arsenic. This mixture he granulates, by pouring into cold water, as Mr. Edwards did, and fuses it a second time for casting. SPERMACETI. See FAT. SPHENE. Prismatic titanium ore. SPIICERUL1TE. Colours brown and gray. In imbedded roundish balls and grains. Glimmering. Fracture even, splintery. Opaque. Scratches quartz with difficulty. Brittle. Sp. gr. 2-4 to 2-5. Nearly infusible. It occurs in pearlstone and pitchstone porphyries, in the vicinity of GlasshUtte near Schemnitz ; and in the pitchstone of Meissen. SPHRAGIDE. SJCLEMNIAN EARTH. SPINEL. A sub-species of octohedral corundum. Colour red. Occurs in grains, more frequently crystallized ; in a perfect octohedron, which is the fundamental figure ; in a tetrahedron, perfect or modified ; a thick equiangular six-sided table ; a very oblique four-sided table ; a rhomboidal dodecahedron ; a rectangular four-sided prism. Splendent and vitreous. Cleavage four-fold. Fracture flat conchoidal. Translucent to transparent. Re- fracts single. Scratches topaz, but is scratched by sapphire. Brittle. Sp. gr. 3-5 to 3-8. Fusible with borax. Its constituents are, alumina 82-47, magnesia 8-78, chromic acid 0-18, loss 2-57. Vauqudin. It is found in the gneiss district of Acker in Sudermannland, in a primitive limestone ; in the kingdom of Pegu ; and in Ceylon. It is used as a precious stone. When it weighs four carats (about 16 grains), it is considered of equal value with a diamond of half the weight. Jameson. SPINELLANE. Colour plum-blue. It occurs crystallized in rhomboids of 117 23', and 62 37' ; and in six-sided prisms acumin- ated with three planes. It scratches glass. It is found on the shores of the lake of Laach, in a rock composed of glassy felspar, quartz, hornblende, &c. It is said to be a variety of Haiiyne. SPINTHERE. Colour greenish-gray. In small oblique double four-sided pyramids. It does not scratch glass. It occurs in the de- partment of Isere in France, incrusting cal- careous spar crystals. It is believed to be a variety of sphene. SPIRIT OF MINDERERUS. A solu- tion of acetate of ammonia, made by adding concrete carbonate of ammonia to distilled vinegar till saturation takes place. SPIRIT OF NITRE. See ACID (NI- TRIC). SPIRIT (PYRO ACETIC). Some dry acetates exposed to heat in a retort yield a quantity of a light volatile spirit, to which the above name is given. When the acetate is easily decomposed by the fire, it affords much acid and little spirit ; and on the contrary it yields much spirit and little acid, when a strong heat is required for its decomposition. The acetates of nickel, copper, &c. are in the first condition ; those of barytes, potash, soda, strontian, lime, manganese, and zinc, are in the second. The following table of M. Chenevix, exhibits the products of the distil- lation of various, acetates. SPI 738 SPO Talk of Pyro- Acetic Spirit. Acetate of Acetate of Acetate of Acetate of Peracetate Acetate of Acetate of Silver. Nickel. Copper. Lead. of Iron. Zinc. Manaanese. Loss by the fire. 0-36 0-61 0-64 0-37 0-49 0555 f State of the \ base (a). 1) metallic. metallic. metallic. metallic. D!. oxide. wh. oxide. l>r. oxide. & v Resitl. Carbon. 0-05 0-14 0-055 0-04 0-02 005 0-035 2ffsp.gr. 1-0656 1 -0398 1-055C 0-9407 1-011 0-8452 0-8264 .S'-jji Ratioofacid. 107-309 44731 84-863 3-045 27-236 2-258 l-28-> J > pyro. spir. almost 0-17 0-555 0-24 0-695 094 /-Carb.acid(&). < Carb. hydro. Jjy. Total gas. 8 12 20 35 60 95 10 34 44 20 8 28 18 34 52 16 28 44 20 32 52 We see, that of all the acetates, that of silver gives the most concentrated and purest acetic acid, since it contains no pyro-acetic spirit. This spirit is limpid and colourless. Its taste is at first acrid and burning, then cool- ing, and in some measure urinous- Its odour approaches that of peppermint mingled with bitter almonds. Its sp. gr. is 0-7864. It burns with a flame interiorly blue, but white on the outside. It boils at 138-2 F. and does not congeal at 5 F. With water it combines in every proportion, as well as with alcohol, and most of the essential oils. It dissolves but a little of sulphur and phosphorus, but camphor in very large quantity. Caustic potash has very little action on the pyro-acetic spirit. Sulphuric and nitric acids decompose it ; but muriatic acid forms with this body a compound, which is not acid, and in which we can demonstrate the presence of the muriatic acid only by igneous decompo- sition. Hence we perceive th-it pyroacetic spirit is a peculiar suftstance, which resembles the ethers, alcohol, and volatile oils. To obtain it cheaply, we may employ the acetate of lead of commerce. After having distilled this salt in an earthen retort, and collected the liquid products in a globe, communicating by a tube with a flask surrounded with ice, we saturate these products with a solution of potash or soda, and then separate the spirit by means of a second distillation, taking care to use a regulated heat. As it usually carries (a.) Almost all the metallic residuums are pyrophoric. or susceptible of inflaming by contact of air, after complete refrigeration ; which M. Chenevix ascribes to the finely divided charcoal mixed with the metallic part. (6.) The quantities marked here are ex- pressed in volumes. over with it a little water, it is proper to rectify it from dry muriate of lime. Ann. de Chimie, torn. 69. See PYROXILIC spirit, SPIRIT or SAL AMMONIAC. Water of ammonia. SPIRIT (VOLATILE) OF SAL AM- MONIAC. See AMMONIA. SPIRIT OF SALT. See ACID (MU- RIATIC). SPIRIT OF WINE. Alcohol. SPODUMENE. Prismatic triphane spar. Mohs, Colour between greenish- white and mountain-gray. Massive, disseminated and in large granular concretions. Glistening, pearly. Cleavage, threefold. Fracture fine grained uneven. Translucent. As hard as felspar. Most easily frangible. Sp. gr. 3-0 to 3- 1 . Before the blowpipe, it first separates into small gold- yellow coloured folia ; and if the heat is continued, .they melt into a greenish- white coloured glass. Its constituents are, silica 64-4, alumina 24-4, lime 3, potash 5, oxide of iron 2-2. Vauquclin. It was first discovered in the island of Uton in Suder- mannland, where it is associated with red felspar and quartz. It has been lately found in the vicinity of Dublin, by Dr. Taylor. It contains the new alkali lithia, by some recent analyses. SPONGE. A soft, light, very porous, and compressible substance, readily imbibing water, and distending thereby. It is found adhering to rocks, particularly in the Mediterranean Sea, about the islands of the Archipelago. It was formerly supposed to be a vegetable pro- duction, but is now classed among the zoophytes ; and analyzed, it yields the same principles with animal substances in general. Sponges may be bleached by soaking and squeezing them first in cold water for several days, and then in warm water. If they be now washed with cold water, slightly acidulated with sulphuric acid, starch will detect iodine STA 739 STA in the liquid which contains hydriodate of potash. The calcareous matter contained in the sponge is best removed by a dilute rfcuriatic acid. After washing in water, they are to be put into aqueous sulphurous acid, sp. gr. 1-034, and left for 8 days, during which time they are to be occasionally squeezed. When well blanched, they are to be washed in much water, moistened with orange-flower water, arid slowly dried in the air. Vogel^ Journ. dc Pharm. x. 409. STALACTITES. These are found sus- pended from vaults, being formed by the oozing of water charged with calcareous par- ticles, and gradually evaporating, leaving those particles behind. STANNANE. Protochloride of tin. STARCH. This is a white, insipid, com- bustible substance, insoluble in cold water, but forming a jeHy with boiling water. It exists chiefly in the white and brittle pans of vegetables, particularly in tuberose roots, and the seeds of the gramineous plants. It may be extracted by pounding these parts, and agitating them in cold water ; when the pa- renchyma, or fibrous parts, will first subside ; and these being removed, a fine white powder, diffused through the water, will gradually subside, which is the starch. Or the pounded or grated substance, as the roots of arum, potatoes, acorns, or horse chestnuts, for in- stance, may be put into a hair-sieve, and the starch washed through with cold water, leaving the grosser matters behind. Farinaceous seeds may be ground and treated in a similar manner. Oily seeds require to have the oil expressed from them before the farina is extracted. If starch be subjected to distillation, it gives out water impregnated with empyreumatic acetous acid, a little red or brown oil, a great deal of carbonic acid, and carburetted hydrogen gas. Its coal is bulky, easily burned, and leaves a very small quantity of potash and phosphate of lime. If when diffused in water it be exposed to a heat $ 60 F., or upward, it will ferment, and turn sour ; but much more so if it be not freed from the gluten, extract, and colouring matter. Thus, in Starch-making, the farina ferments and becomes sour, but the starch that does not undergo fermentation is rendered the more pure by this process. Some water already soured is mixed with the flour and water, which regulates the fermentation, and prevents the mixture from becoming putrid ; and in this state it is left about ten days in summer, and fifteen in winter, before the scum is removed, and the water poured off. The starch is then washed out from the bran, and dried, first in the open air, and finally in an oven. With boiling water starch forms a nearly transparent mucilage, emitting a peculiar smell, neither disagreeable nor very powerful: This mucilage may be dried, and will then be semitransparent, and much resembling gum^ all the products of which it affords. When dissolved, it is much more easily digested and nutritious than before it has undergone this operation. Both acids and alkalis combined with water dissolve it. It separates the oxides of several metals from their solutions, and takes oxygen from many of them. It is found naturally combined with all the immediate principles of vegetables, and may easily be united with most of them by art. Wherrstarch is triturated with iodine, it forms combinations of various colours. When the proportion of iodine is small, these com- pounds are violet ; when somewhat greater, blue ; and when still greater, black. We can always obtain the finest blue colour, by treating starch with an excess of iodine, dissolving the compound in liquid potash, and precipitating by a vegetable acid. The colour is manifested even at the instant of pouring water of iodine into a liquid which contains starch diffused through it. Hence iodine becomes an excellent test for detecting starch ; and starch for detecting iodine. Besides these combinations, it appears that there is another of a white colour, in which the iodine exists in very small quantity. All of them possess peculiar properties, which have been described by MM. Colin and Gauthier Claubry, (Anna I. dc Chimie, xc. 92.), and M. Pelletier, (Bul- letin dc Pharmacie. vi. 289.) Starch is not affected in the cold, by water, alcohol, or ether. But it dissolves readily when triturated with potash water. When to the solution of starch in hot water, we pour in a boiling-hot solution of sub-nitrate of lead, and leave the mixture for a considerable time at rest, a precipitate falls, which is found after washing and drying to consist of 100 starch and 38 89 protoxide of lead. --Berzelius, Ann. de Chimic, xcv. 82. Starch is convertible into sugar by dilute sulphuric acid. To produce this change we must take 2000 parts of starch, diffuse them in 8000 parts of water, containing 40 parts of strong oil of vitriol ; and boil the mixture for 36 hours in a basin of silver or lead, taking care to stir the materials with a wooden rod, during the first hour of ebullition. At the end of this time, the mass having become liquid, does not require to be stirred, except at intervals. In proportion as the water evapo- rates, it ought to be replaced. When the liquor has been sufficiently boiled, we must add to it chalk and animal charcoal, then clarify with white of egg, filter the mixture through a flock of wool, and then concentrate the liquid till it has acquired a syrupy con- sistence. After this, the basin must be re- moved from the fire, in order that, by cooling, the greater part of the sulphate of lime may fall down. The pure syrup is now to be de- canted off, and evaporated to the proper dry- 3B2 STA 710 STE ness. The greater the quantity of acid em. ployed, the less ebullition is required to eon- vert the starch into the saccharine matter. Voge.l, Ann. dc Chimic, Ixxxii. 148. The discovery of the preceding process is due to M. Kirchoff of St. Petersburg!!. M. Th. de Saussure has ascertained, that no gas is given off during the operation ; that the access of air is not essential to it; that the sulphuric acid is not decomposed ; and that 100 parts of starch produce 110.14 of sugar. The presence of sulphuric acid is not indis- pensable for obtaining sugar from starch. It may also be obtained by leaving the starch to itself, either with or without contact of air, or by mixing it with dried gluten. At the same * time, indeed, several other products are formed. M. Th. de Saussure's interesting observations on this subject are published in the Annalcs de Chimie et de Physique, xi. 370. The starch, brought to the state of a pulpy mass, must be left to spontaneous decomposition. The products are, 1st, a sugar, like the sugar of grapes ; 2d, Gum, like that from roasted starch ; 3d, Amidine, a body whose properties are intermediate between those of starch and gum ; and, 4th, an insoluble substance, like ligneous matter. In these experiments, the mass on which he operated was made by pouring 12 parts -of boiling water on 1 of starch. When it was fermented by dry gluten, he obtained Without contact With contact oi'aii. of air. Sugar, 47-4 497 Gum, 23-0 97 Amadine, 8-9 5-2 Amilaceous lignin, 10-3 9-2 Lignin with charcoal, A trace 0-3 Undecomposed starch, 4-0 3-8 Potato starch differs perceptibly from that of wheat ; it is more friable ; is composed of ovoid grains about twice the size of the other ; it requires a lower temperature to reduce it into a jelly with water ; it is soluble in more dilute alkaline leys, and is less readily decom- posed by spontaneous fermentation. It also contains more hygrometric water; for 100 parts of it dried at the temperature of boiling water lost 1C 41 parts of water; whilst wheat starch lost by the same process only 13-66. They had both been previously exposed .for some time to a dry atmosphere, at the heat of 72-5 Fahr. Starch is composed of Gay Lussac and Thenard. Berzelius. Saussure. Carbon, 43-55 43481 4539 Oxygen, 49-68 49-455 48-31 Hydrogen, 6-77 7064 5-90 10000 100-000 99-60 Azote, 0-4 10000 When starch is roasted at a moderate heat in an oven, it is converted into a species of gum, employed by the calico printers. Potato starch answers best for this purpose. S^e BRITISH GUM. M. Caventou considers starch paste made with hot water as containing the same thing as the amidine of M. de Saussure. Salop, according to him, is composed of a little gum, very little starch, and much bassorine. SaffO is an uniform substance, soluble in cold water, more so in hot, precipitated blue by iodine, and differing from common starch in the first property. Tapioca seems to be identical in composi- tion with sago. Arrow root is nearly pure starch, agreeing in ail respects with the starch of the potato, which may be converted by heat into some- thing similar to sago and tapioca. Annales de Chimie et Physique, xxxi. 337- STAUROLITE. Grenatite, or prismatic garnet. STAUROTIDE. Grenatite, prismatic garnet, or staurolite. Colour dark reddisli- brown. Only crystallized in forms which may be reduced to a prism of 129 30 7 . The following are secondary forms : a very oblique four-sided prism, truncated on the acuter lateral edges, forming an unequiangular six- sided prism ; the same acutely bevelled on the extremities ; and a twin crystal, formed by two perfect six-sided prisms. Splendent, resino - vitreous. Cleavage in the smaller diagonal. Fracture small grained uneven. Opaque, or translucent. Scratches quartz feebly. Brittle. Specific gravity 3.3 to 3.8. Infusible. Its constituents are, alumina 44, silica 33, lime 3.84, oxide of iron 13, oxide of manganese 1, loss 5.16. Vauquflin. The geognostic relations of this mineral are nearly the same with those of precious garnet. It occurs in clay-slate near Ardonald, between Keith and Huntly, in Aberdeenshire ; and in a micaceous reck at the Glenmalur lead-mines in the county of Wicklow, Ireland. STEAM. See CALORIC and VAPOUK. STEARINE. See FAT. STEATITE, OR SOAPSTONE. A sub-species of rhomboidal mica. Colour grayish, or greenish-white. Massive, disse- minated, imitative, and in the following sup- posititious figures : an equiangular six-sided prism ; an acute double six-sided pyramid ; and a rhomboid. The first two are on rock crystal, the last on calcareous spar. Dull. Fracture coarse splintery. Translucent on the edges. Streak shining. Writes but feebly. Soft. Very sectile. Rather difficultly fran- gible. Does not adhere to the tongue. Feels very greasy. Spec. grav. 2.4 to 2.6. Infusi- ble. Its constituents are, silica 44, magnesia 44, alumina 2, iron 7-3, manganese 1.5, chrome STE 741 STE 2. Trac? oflime and muriatic acid. It oc- nirs frequently in small contemporaneous v.ins that traverse serpentine in all directions ; at Portsoy find Shetland ; in the limestone of Icolmkill ; in the serpentine of Cornwall ; and in Anglesey. It is used in the manufacture of porcelain, and for taking greasy spots out of silk and woollen stuffs It is also employed in polishing gypsum, serpentine, and marble. When pounded and slightly burned, it forms the basis of certain cosmetics. It writes readily on glass. Humboldt assures us, that the Otomacks, a savage race on the banks of the Orinoco, live for nearly three months of the y. ar principally on a kind of potters' clay; ar.d many other savages eat great quantities of steatite, which contains absolutely no nourishment. STEEL. A modification of iron, concern- ing which our knowledge is not very precise, notwithstanding the researches of many cele- brated chemists. For the following important facts, I am indebted to the proprietor of the Monkland manufactory, where bar and cast steel of superior quality are made. The chests or troughs in which the iron bars are stratified, are 9 feet long, and com- posed of an open- grained siliceous freestone, unalterable by the fire. The Dannemora or Oregrounds iron is alone employed for con- version into steel at Monkland. The increase of weight is from 4 to 12 ounces per hundred weight. The average is therefore 1 in 224 parts. The first proportion constitutes mild, and the second very hard steel. Should the process be pushed much farther, the steel would then melt, and in the act of fusion would take a dose of charcoal, sufficient to bring it to the state of No. 1. cast iron. The charcoal used in stratifying with the bar iron is bruised so as to pass through a quarter- inch riddle. Whenever the interior of the troughs arrives at 70 Wedgewood, the car- bon begins to be absorbed by the iron. There is no further diminution of the weight of the charcoal than what is due to this combination. What remains is employed at another charge. Great differences are found between the dif- ferent kinds of bar iron imported at the same time; which occasion unexpected differences in the resulting steel. The following letter contains important information, from a gentle- man possessing great experience in the manu- facture of steel. " Monkland Steel-works, " fl//i November, 1820. " Sni, Mr. William Murray has written me, that you wished I should communicate to you the reason why bar iron should run into the state of soft cast iron, by the opera- tion being carried too far in the blister steel furnace, and how it does not make cast steel, as cast steel is said to be formed by the fusion oi' the blister steel iu the crucible with char- coal. " The usual practice of making cast steel, is to fuse common steel in a crucible, without any charcoal being mixed. The degree of hardness required in the cast steel is regulated by selecting blister steel of the proper degree of hardness for what is wanted. " This statement is made with the view to correct a common mistake, that to make cast steel it is necessary, and that it is the practice, to mix with the steel to be melted a quantity of charcoal. u Pursuing this mistake, it naturally leads to others. Dr. Thomson says, when speaking on this subject, that cast steel is more fusible than common steel, and for that reason it can- f not be welded to iron. It melts before it can be heated high enough ; and that the quantity of carbon is greater than in common steel j and that this seems to constitute the difference between the two substances. " The statement of a simple fact will show that this conclusion is erroneous. Suppose a piece of blister steel, pretty hard, yet fit to stand the operation of welding to iron without any difficulty : let this steel be made into cast steel in the ordinary way. It will not then stand the process of welding. It will not melt before reaching the welding heat ; but when brought to that heat, and submitted to the blows of the hammer, it will fall like a piece of sand, and the parts being once sepa- rated, they refuse to become again united. This difficulty of working the steel cannot arise from the steel containing more carbon, for the fact is, it contains less, part of it being burnt out in the operation of melting it. And if the same steel was to be melted a second time, more of the carbon would be burnt out ; of course the steel would be softer, but at the same time;, the difficulty of working it would be increased ; or, in other words, the red-short property it had acquired in the first melting would be doubly increased in the second, al- though a person who has not had the experi- ence would very natuially conclude, that as the metal kept retrograding to the state of malleable iron, in the same proportion it would acquire all the properties of the metal in that state. When taking this view of the subject, it would appear that the difference between these two kinds of steel must arise from some other cause than that pointed out by Dr. Thomson. " When the iron has absorbed a quantity of carbon in the blister steel furnace, sufficient to constitute steel of a proper degree of hardness, and the heat after this is continued to be kept up, the steel will keep absorbing more and more carbon. The fusibility of it will con- tinue to increase, just in the same proportion, till at last it become so fusible, that even the limited heat of a blister steel furnace brings it STE 742 STI .down; and just at the time it is passing to the fluid state, it takes so great a quantity of charcoal, as changes it from the state of steel to that of cast-iron. It appears to me, that the charcoal is combined in rich cast-iron, in the mechanical state, and not in the chemical, as in steel. " With this you will receive a specimen from the blister steel furnace. The fracture of the bar will show you steel in the highest state of combination with carbon in which it can exist ;" and another part of the same frac- ture presents the transition from the state of steel to that of cast-iron. Should you require it, I will send you a specimen of cast-steel in the ingot, and from the same ingot, one in die hammered state. I am, &c. " JOHN BUTTEIIY." A new memoir on the alloys of steel has been lately published by Messrs. Stodart and Faraday, of which the following is an ab- stract. The first curious fact that occurs relates to the compound with silver, of which steel will only retain one 500th part in union; when more was used, it either evaporated, or sepa- rated as the button cooled, or was forced out in forging. The alloy was excellent, and the trifling addition of price furnishes no obstacle to its general employment. Steel, alloyed with 100th part of platinum, though not so hard as the silver alloy, has more toughness ; hence its value, where tena- city as well as hardness are required: the extra cost is more than repaid by its excel- lence. The alloy with rhodium exceeds the former in its valuable qualities, but the scarcity of the metal precludes its general use. To the compounds with iridium and osmium the same remarks apply. The action of acids on these alloys is curious, and especially in respect to that of platinum, which is acted upon by dilute sulphuric acid with infinitely greater rapidity than the un- alloyed steel; indeed, an acid that scarcely touches the pure steel, dissolves the alloy with energetic effervescence. This is no doubt referable to electrical excitation ; and we should apprehend that it would be fatal to the employment of this particular alloy, in any case where chemical action is likely to ensue. The alloys of steel with gold, tin, copper, and chromium, we have not attempted in the large way. In the laboratory, steel and gold were combined in various proportions ; none of the resu'lts were so promising as the alloys already named, nor did either tin or copper, as far as we could judge, at all improve steel. With titanium we failed, owing to the imper- fection of crucibles. In one instance, in which the fused button gave a fine damask surface, we were disposed to attribute the ap- pearance to the presence of titanium ; but in this we were mistaken. The fact was, we had unintentionally made wootz. The but- ton, by analysis, gave a little silex and alu- mina, but not an atom of titanium. Mena- chanite, in a particular state of preparation, was used; this might possibly contain the earths or their basis, or they may have formed a part of the crucible. Our authors advert to the probable import- ance of certain triple alloys, only one of which is noticed in their paper, namely, that of steel, iridium, and osmium. " Some attempts to form other combinations of this description proved encouraging, but we were prevented at the time from bestowing on them that attention and labour they seemed so well to deserve." The following is an important and curious paragraph of this paper: When pure iron is substituted for steel, the alloys so formed are much less subject to oxi- dation. 3 per cent, of iridium and osmium, fused with some pure iron, gave a button, which, when forged and polished, was ex- posed with many other pieces of iron, steel, and alloys to a moist atmosphere ; it was the last of all in showing any rust. The colour of this compound was distinctly blue ; it had the property of becoming harder when heated to redness, and quenched in a cold fluid. On observing this steel-like character, we sus- pected the presence of carbon ; none, however, was found, although carefully looked for. It is not improbable that there may be other bodies, besides charcoal, capable of giving to iron the properties of steel ; and though we cannot agree with M. Boussingault, Annalcs de Chimie, xvi. 1, when he would replace carbon in steel by silica, or its base, we think his experiments very interesting on this point, which is worthy of farther ex- amination. In conclusion, our authors observe, that to succeed in making these compounds, much attention is requisite on the part of the ope- rators ; that the purity of the metals is essen- tial ; that the perfect and complete fusion of both must be ensured; that they must be kept a considerable time in a state of thin fusion ; that, after casting, the forging is with equal care to be attended to ; that the metal must on no account be overheated ; and that the hardening and tempering must be most carefully performed. Upon the whole, though we consider these researches upon the alloys of steel as very interesting, we are not sanguine as to their important influence upon the improvement of the manufacture of cutlery, and suspect that a bar of the best ordinary steel, selected with precaution, and most carefully forged, wrought, and tempered, tinder the immediate inspection STR 743 STR of the master, would afford cutting instru- ments as perfect and excellent as those com- posed of wootz, or of the alloys. ritil. Trans. 1822. STEINHEILITE. Blue quartz of Fin- laud. STIBIU3I. Antimony. STILBITE, OB PYRAMIDAL ZEO- LITE. See ZEOLITE. STILPNOSIDERITE. Colour brown- ish-black. Massive, imitative, and in curved concretions. Splendent, resinous. Fracture conchoidal. Opaque. Streak yellowish- brown. Hard in a low degree. Brittle. 8p. gr. 3-77' With borax it gives a dark olive- green glass. Its constituents are, oxide of iron 80.5, silica 2.25, water 16, oxide of manganese a trace. Uttmann. It is said to contain phosphoric acid. It occurs along with brown iron in Saxony and Bavaria. It is allied to meadow iron-ore. STINKSTONE, OR SWINESTONE. A variety of compact lucullite, a sub-species of limestone. STONES. See ANALYSIS, EARTHS, GEOLOGY, METEOROLITE, and MINER- ALOGY. STORAX. A balsam, of which there are two varieties, a solid and liquid ; consisting of resin, benzoie acid, and essential oil. STRAHLSTEIN. Actinolite. STR ON TI A. About forty years ago, a mineral was brought to Edinburgh by a dealer in fossils, from a lead-mine at Strontian in Argyllshire, which was generally considered as a carbonate of barytes. It has since been found n'.ar Bristol, in France, in Sicily, and in Pennsylvania. Dr. Crawford first observed vsome differences between its solution iu muri- atic acid, and that obtained from the carbonate of barytes of Anglezark, and thence supposed it to be a nu'.v earth. Dr. Hope of Edinburgh had entertained the same opinion, and con- firmed it by experiments in 1791. Kirwan, Klaproth, Pelletier, and Sulzer did the same. The carbonic acid may be expelled by a heat of 140 of Wedgewood, leaving the strontia behind ; or by dissolving in the nitric acid, and driving this off by heat. Pure strontia is of a grayish- white colour ; a pungent, acrid taste ; and when powdered in a mortar, the dust that rises irritates the lungs and nostrils. Its specific gravity ap- proaches that of barytes. It requires rather more than 1GO parts of water at 60 to dis- solve it ; but of boiling water much less. On cooling, it crystallizes in thin, transparent, quadrangular plates, generally parallelograms, seldom exceeding a quarter of an inch in length, and frequently adhering together. The edges are most frequently bevelled from each side. Sometimes they assume a cubic form. These crystals contain about .t8 of water ; are soluble in 51.4 times their weight of writer at 60, and in little more than twice their weight of boiling water. They give a blood-red colour to the flame of burning alco- hol. The solution of strontia changes vege- table blues to a green. Strontia combines with sulphur either in the wet or dry way, and its sulphuret is soluble in water. In its properties, strontia has a consider- able affinity to barytes. It differs from it chiefly in being infusible, much less soluble, of a different form, weaker in its affinities, and not poisonous. Its saline compounds afford differences more marked. Edinburgh Trans. The basis of strontia is strontium, a metal first procured by Sir H. Davy in 1808, pre- cisely in the same manner as barium, to which it is very analogous, but has less lustre. It ' appeared fixed, difficultly fusible, and not volatile. It became converted into stroutia by exposure to air, and when thrown into water, decomposed it with great violence, pro- ducing hydrogen gas, and making the water a solution of strontia. By igniting the mineral strontianite (see HEAVY SPAR) intensely with charcoal powder, strontia is cheaply procured. Sir H. Davy, from indirect experiments, is disposed to regard it as composed of about 8C strontium -j- 14 oxygen, in 100 parts ; and supposing it to be composed of a prime pro- portion of each constituent, the equivalent prime of strontium would be 0.143, and of strontia 7-143. But from the proportions of the constituents in the carbonate, the prime of strontia appears to be 6.4 or 6.5 j and hence that of strontium will be 5.5. The beautiful red fire which is now so frequently used at the theatres, is composed of the following ingredients : 40 parts dry nitrate of strontian, 13 parts of finely powdered sul- phur, 5 paits of chlorate of potash (hypcroxy- muriate), and 4 parts of sulphuret of antimony. The chlorate of potash and sulphuret of anti- mony should be powdered separately in a mortar, and then mixed together on paper ; after which they may be added to the other ingredients, previously powdered and mixed. No other kind of mixture than rubbing to- gether on paper is required . Sometimes a little realgar is added to the sulphuret of antimony, and frequently when the tire burns dim and badly, a very small quantity of very finely powdered charcoal or lampblack will make it perfect. For the saline combinations of strontia, see the ACIDS at the beginning of the Dictionary, or Dr. Hope's Dissertation on this Earth, in the Edin. Phil. Trans, for 1790. STRONTIANITE. See HE VY SPAR. STRONTITES. The same as strontia. STRONTIUM. The metallic base of strontia. STRYCHNIA. This alkaline substance was detected by Pelletier and Caventou in the STR 744 STR fruit of the strychnos nnx vomica, and strych- non tgnatia, about the end of the year 1818. It was obtained from the bean of the strychnos ignatia by the following process: The bean was rasped down as small as possible. It was then exposed to the action of nitric ether in a Papin's digester. The residue thus deprived of a quantity of fatty matter was digested in alcohol as long as that reagent was capable of dissolving any thing. The alcoholic solutions were evaporated to dryness, and the residue redissolved in water. Caustic potash being dropped into the solution, a white crystalline precipitate fell, which was strychnia. It was purified by washing it in cold water, dis- solving it in alcohol, and crystallizing it. Strychnia was obtained likewise from the bean of the strychnos ignatiaby boiling the infusion of the bean with magnesia, in the same manner as Robiquet had obtained morphia from the infusion of opium. Strychnia has been since extracted from the Upas poison (Upas tiente and Upas anthiar) by the same chemists. It constitutes the poisonous principle of these plants. Ann. de Chim. ct de Phys. xxvi. 44. The properties of strychnia, when in a state of purity, are as follows : It is crystallized in very small four-sided prisms, terminated by four-sided low pyra- mids. It has a white colour, its taste is in- tolerably bitter, leaving a metallic impression in the mouth. It is destitute of smell. It is not altered by exposure to the air. It is neither fusible nor volatile, except at tempe- ratures at which it undergoes decomposition. It is charred at the temperature at which oil enters into ebullition (about 580). When strongly heated, it swells up, blackens, gives out empyreumatic oil, a litde water and ace- tic acid ; carbonic acid and carburetted hy- drogen gases are disengaged, and a bulky charcoal remains behind. When heated with peroxide of copper, it gives out only carbo- nic acid gas and water. It is very little so- luble in cold water, 100,000 parts of that liquid dissolving only 15 parts of strychnia ; but it dissolves in 2,500 times its weight of boiling water. A cold solution of strychnia in water may be diluted with 100 times its volume of that liquid without losing its bitter taste. When strychnia is introduced into the sto- mach, it acts with prodigious energy. A locked jaw is induced in a very short time, and the animal is speedily destroyed. Half a grain of strychnia blown into the throat of a rabbit proved fatal in five minutes, and brought on locked jaw in two minutes. Sulphate of strychnia is a salt which crys- tallizes in transparent cubes, soluble in less than ten times its weight of cold water. Its taste is intensely bitter, and the strychnia is precipitated from it by all the soluble salin- able bases. It is not altered by exposure to the air. In the temperature of 212 it lose* no weight, but becomes opaque. At a higher temperature it melts, and speedily congeals again, with a loss of three per cent, of its weight. At a still higher temperature it is decomposed and charred. Its constituents are, Sulphuric acid, 9-5 5-00 Strychnia, 90-5 47-63 100-0 Muriate of strychnia crystallizes in very small needles, which are grouped together, and before the microscope exhibit the form of quadrangular prisms. When exposed to the air it becomes opaque. It is more soluble in water than the sulphate, has a similar taste, and acts with the same violence upon the ani- mal economy as all the other salts of strychnia. \Vhen heated to the temperature at which the base is decomposed, it allows the muriatic acid to escape. Phosphate of strychnia crystallizes in four- sided prisms. It can only be obtained neutral by double decomposition. 'Nitrate of strychnia can be obtained only by dissolving strychnia in nitric acid, diluted with a great deal of water. The saturated solution, when cautiously evaporated, yields crystals of neutral nitrate in pearly needles. This salt is much more soluble in hot than in cold water. Its taste is exceedingly bitter, and it acts with more violence upon the ani- mal economy than pure strychnia. It seems capable of uniting with an excess of acid. When heated it becomes yellow, and undergoes decomposition. It is slightly soluble in alcohol, but is insoluble in ether. When concentrated nitric acid is poured upon strychnia, it immediately strikes an amaranthine colour, followed by a shade si- milar to that of blood. To thid colour suc- ceeds a tint of yellow, which passes afterwards into green. By this action, the strychnia seems to be altered in its properties, and to be con- verted into a substance still capable of uniting with acids. Carbonate of strychnia is obtained in the form of white flocks, little soluble in water, but soluble in carbonic acid. Acetic, oxalic, and tartaric acids, form with strychnia neutral salts, which are very soluble in water, and more or less capable of crystal- lizing. They crystallize best when they contain an excess of acid. The neutral ace- tate is very soluble, and crystallizes with dif- ficulty. Hydrocyanic acid dissolves strychnia, and forms with it a crystallizable salt. Strychnia combines neither with sulphur nor carbon. When boiled with iodine, a solution takes place, and iodate and hydriodate of strych- nia are formed . Chlorine acts upon it precisely in the same way. SUB 745 SUB Strychnia, when dissolved in alcohol, has the property of precipitating the greater number of metallic oxides from their acid solutions. It is precipitated by the alkalis and alkaline earths : but the effect of the earths proper has not been tried. See Ann. de Chim, et de Phys. x. 142. A new process for extracting strychnia from nux vomica has been lately published by M. Henry, in the Journal de Pharmacie for September 1822. The details are inserted in the Journal of Science and the Arts, xiv. 443, Another process is given in the Gior. de Fisica by M. Ferrari, which is translated into the Journal of Science, xvii. 170. M. Ferrari further remarks that the solutions of the salts of strychnia, as of the sulphate, nitrate, mu- riate, and acetate slightly acid, when exposed to a heat of 212, become volatile, and the salt evaporates. STUCCO. Gypsum. SUBER. Cork. See CERIN, and ACID (SUBERIC). SUBLIMATION is a process by which volatile substances are raised by heat, and again condersed in the solid form. This operation is founded on the same principles as distillation, and its rules are the same, as it is nothing but a dry distillation. Therefore all that has been said on the article DISTILLATION is applicable here, especially in those cases where sublimation is employed to separate volatile substances from others which are fixed or less volatile. Sublimation is also used in other cases : for instance, to combine volatile matters together, as in the operation of the sublimates of mer- cury ; or to collect some volatile substances, as sulphur, the acid of borax, and all the pre- parations called flowers. The apparatus for sublimation is very simple. A matrass or small alembic is ge- nerally sufficient for the sublimation of small quantities of matter. But the vessels, and the method of managing the lire, vary according to the nature of the matters which are to be su- blimed, and according to the form which is to be given to the sublimate. The beauty of some sublimates consists in their being composed of very fine, light parts, such as almost all those called flowers ; as flowers of sulphur, of benzoin, and others of this kind. When the matters to be sub- limed are at the same time volatile, a high cucurbit, to which is adapted a capital, and even several capitals placed one upon another, are employed. The sublimation is performed in a sand bath, with only the precise degree of heat requisite to raise the substance which is to be sublimed, and the capitals are to be guarded as much as possible from heat. The height of the cucurbit and of the capital seems well contrived to accomplish this in- tention. When along with the dry matte* which is to be collected in these sublimations, a certain quantity of some liquor is raised, as happens in the sublimation of acid of bo- rax, and in the rectification of volatile con- crete alkali, which ?s a kind of sublimation, a passage and a receiver for these liquors must be provided. This is conveniently done by using the ordinary capital of the alembic, furnished with a beak and a re- ceiver. Some sublimates are required to be in masses as solid and compact as their natures allow. Of this number are camphor, muriate of ammonia, and all the sublimates of mer- cury. The properest vessels for these sub- limations are bottles or matrasses, which are to be sunk more or less deeply in sand, ac- cording to the volatility and gravity of the matters that are to be sublimed. In this manner of subliming, the substances having quitted the bottom of the vessel, adhere to its upper part, and as this part is low and near the fire, they there suffer a degree of heat suf- ficient to give them a kind of fusion. The art, therefore, of conducting these sublimations consists in applying such a degree of heat, or in so disposing the sand (that is, making it cover more or less the matrass 1, that the heat in the upper part of the matrass shall be suf- ficient to make the sublimate adhere to the glass, and to give it such a degree of fusion as is necessary to render it compact ; but at the same time this heat must not be so great as to force the sublimate through the neck of the ma- trass, and dissipate it. These conditions are not easily to be attained, especially in great works. Many substances may be reduced into flowers, and sublimed, which require for this purpose a very great heat, with the access of free air and even the contact of coals, and therefore cannot be sublimed in close vessels. Such are most soots or flowers of metals, and even some saline substances. When these sublimates are required, the matters from which they are to be separated must be placed among burning coals in open air ; and the flowers are collected in the chimney of the furnace in which the operation is performed. The tutty, calamine, or pompholix, collected in the upper part of furnaces in which ores are smelted, are sublimates of this kind. SUBLIMATE (COliROSIVE> Bichlo- ride of mercury. SUBSALT. A salt having an excess of base beyond what is requisite for saturating the acid, as super salt is one with an excess of the acid. The sulphate of potash is the neu- tral compound of sulphuric acid and potash ; subsulphate of potash, a compound of the same ingredients, in which there is an excess of base ; supersulphate of potash, a compound of the same acid and the same base, in which SUG 746 SUG there is an excess of acid. The term was introduced by Dr. Pearson. SUCCINATES. Compounds of succinic acid with the salifiable bases. SUCCINIC ACID. See ACID (Sue- CINIC). SUGAR is a constituent part of vegeta- bles, existing in considerable quantities in a number of plants. It is afforded by the ma- ple, the birch, wheat, and Turkey corn. Margraaf obtained it from the roots of beet, red beet, skirret, parsnips, and dried grapes. The process of this chemist consisted in di- gesting these roots, rasped, or finely divided, in alcohol. This fluid dissolves the sugar; and leaves the extractive matter untouched, which falls to the bottom. In Canada, the inhabitants extract sugar from the maple. At the commencement of spring, they heap snow in the evening at the foot of the tree, in which they previously make apertures for the passage of the returning sap. Two hundred pounds of this juice afford, by evaporation, fifteen of a brownish sugar. The quantity prepared annually amounts to fif- teen thousand weight. Dr. Rush, in the Transactions of the Ame- rican Philosophical Society, vol. iii. has given an account, at length, of the sugar maple tree, of which the following is a short ab- stract : The acer saccharinum of Linnaeus, or sugar maple tree, grows in great quantities in the western counties of all the middle States of the American Union. It is as tall as the oak, and from two to three feet in diameter ; puts forth a white blossom in the spring, before any appearance of leaves ; its small branches afford sustenance for cattle, and its ashes afford a large quantity of excellent potash. Twenty years are required for it to attain its full growth. Tapping does not injure it ; but, on the con- trary, it affords more syrup, and of a better quality, the oftener it is tapped. A single tree has not only survived, but flourished, after tapping, for forty years. Five *>r six pounds of sugar are usually afforded by the sap of one tree ; though there are instances of the quantity exceeding twenty pounds. The sugar is separated from the sap either by freez- ing, by spontaneous evaporation, or by boiling. The latter method is the most used. Dr. Rush describes the process ; which is simple, and practised without any difficulty by the farmers. From frequent trials of this sugar, it does not appear to be in any respect inferior to that of the West Indies. It is prepared at a time of the year when neither insect, nor the pollen of plants, exist to vitiate it, as is the case with common sugar. From calculations grounded on facts, it is ascertained, that America is now capable of producing a sur- plus of one-eighth more than its own consump- tion ; that i, on the whole, about 135,000,000 pounds; which, in the country, may be valued at fifteen pounds weight for one dol- lar. The Indians likewise extract sugar from the pith of the bamboo. The beet has lately been much cultivated in Germany, for the purpose of extracting sugar from its root. For this the roots are taken up in autumn, washed clean, wiped, sliced lengthwise, strung on threads, and hung up to dry. From these the sugar is extracted by maceration in a small quantity of water ; drawing off this upon fresh roots, and adding fresh water to the first roots, which is pgain to be employed the same way, so as to get out all their sugar, and saturate the water as much as possible with it. This water is to be strained and boiled down for the sugar. Some merely express the juice from the fresh roots, and boil this down ; others boil the roots ; but the sugar extracted in either of these ways is not equal in quality to the first. Professor Lampadius obtained from HOlbs. of the roots, 41bs. of well grained white pow- der sugar ; and the residuums afforded 7 pints of a spirit resembling rum. A chard says, that about a ton of roots produced him lOOlbs. of raw sugar, which gave 5olbs. of refined sugar, and 25lbs. of treacle. But the sugar which is so universally used is afforded by the sugar cane (arundo sac- charifera) which is raised in our colonies. When this plant is ripe, it is cut down, and crushed by passing it between iron cylinders placed perpendicularly and moved by water or animal strength. The juice which flows out by this strong pressure is received in a shallow trough placed beneath the cylinder. The juice is called in the French sugar colo- nies vesou ; and the cane, after having under- gone this pressure, is called bepasse. The juice is more or less saccharine, according to the nature of the soil on which the cane has grown, and the weather that has predomi- nated during its growth. It is aqueous when the soil or the weather has been humid ; and in contrary circumstances it is thick and gluti- nous. The juice of the cane is conveyed into boil- ers, where it is boiled with wood ashes and lime. It is subjected to the same operation in three several boilers, care being taken to remove the scum as it rises. In this state it is called syrup ; and is again boiled with lime and alum till it is sufficiently concentrated, when it is poured into a vessel called the cooler. In this vessel it is agitated with wooden stirrers, which break the crust as it forms on the surface. It is afterwards poured into casks, to accelerate its cooling ; and while it is still warm, it is conveyed into barrels standing up- right over a cistern, and pierced through their SUG 747 SUG bottom with several holes stopped with cane. The syrup which is not condensed filters through these canes into the cistern beneath ; and leaves the sugar in the state called coarse sugar, or muscovado. This sugar is yellow and fat, and is purified in the islands in the following manner : The syrup is boiled, and poured into conical earthen vessels, having a small perforation at the apex, which is kept closed. Each cone, reversed on its apex, is supported in another earthen vessel. The syrup is stirred together, and then left to crys- tallize. At the end of fifteen or sixteen hours, the hole in the point of each cone is opened, that the impure syrup may run out. The base of these sugar loaves is then taken out, and white pulverized sugar substituted in its stead, which being well pressed down, the whole is covered with clay, moistened with water. This water filters through the mass, carrying the syrup with it which was mixed with the sugar, but which by this manage- ment flows into a pot substituted in the place of the first. This second fluid is called fine syrup. Care is taken to moisten and keep the clay to a proper degree of softness, as it becomes .dry. The sugar loaves are afterward taken out, and dried in a stove for eight or ten days; after which they are pulverized, packed, and exported to Europe, where they are still farther purified. The operation of the French sugar refiners consists in dissolving the cassonade, or clayed sugar, in lime water. Bullocks' blood is added, to promote the clarifying : and, when the liquor begins to boil, the heat is diminished, and the scum carefully taken off. It is in the next place concentrated by a brisk heat ; and, as it boils up, a small quantity of butter is thrown in, to moderate its agitation. When the boil- ing is sufficiently effected, the fire is put out ; the liquor is poured into moulds, and agitated, to mix the syrup together with the grain sugar already formed. When the whole is cold, the moulds are opened, and the loaves are covered with moistened clay, which is renewed from time to time till the sugar is well cleansed from its syrup. The loaves being then taken out of the moulds, are carried to a stove, where they are gradually heated to 145 F. They remain in this stove eight days, after which they are wrapped in blue paper for sale. The several syrups treated by the same methods afford sugars of inferior qualities ; and the last portion, which no longer affords any crvstals, is sold by the name of melasscs. The Spaniards use this melasses in the pre- paration of sweetmeats. A solution of sugar, much less concentrated than that we have just been speaking of, lets fall by repose crystals, which affect the form of tetrahedral prisms, terminated by dihedral summits, and known by the name of sugar- candy. The preceding account of the manufacture of sugar in the colonies is chiefly extracted from Chaptal. The following is taken from Edwards' History of the West Indies, the au- thority of which is indubitable. Such planters as are not fortunately fur- nished with the means of grinding their canes by water are at this season frequently im- peded by the failure or insufficiency of their mills ; for though a sugar mill is a very simple contrivance, yet great force is requisite to make it vanquish the resistance which it necessarily meets with. It principally consists of three upright iron rollers or cylinders, from thirty to forty inches in length, and from twenty to twenty-five inches in diameter ; and the mid- dle one, to which the moving power is applied, turns the other two by means of cogs. The canes, which are previously cut short and tied into bundles, are twice compressed between these rollers; for after they have passed through the first and second rollers, they are turned round the middle one by a piece of frame-work of a circular form, which is called in Jamaica the dumb-returner, and forced back through the second and third. By this operation they are squeezed completely dry, and .sometimes even reduced to powder. The cane-juiee is received in a leaden bed, and thence conveyed into a vessel called the receiver. The refuse, or macerated rind of the cane, which is called cane-trash, serves for fuel to boil the liquor. The juice from the mill usually contains eight parts of pure water, one part of sugar, and one part made up of gross oil and muci- lage, with a portion of essential oil. The proportions are taken at a medium ; for some juice has been so rich as to make a hogshead or sixteen hundred weight of sugar from thir- teen hundred gallons, and some is so watery as to require more than double that quantity. The richer the juice is, the less it abounds with redundant oil and gum ; so that very little knowledge of the contents of any other quantity can be obtained by the most exact analysis of any one quantity of juice. The following matters are likewise usually contained in cane-juice. Some of the green tops, which serve to tie the canes in bundles, are often ground in, and yield a raw acid juice, exceedingly disposed to ferment and render the whole liquor sour. Beside these they grind in some pieces of the ligneous part of the cane, some dirt, and lastly, a substance of some im- portance, which may be called the crust. This substance is a thin black coat of matter that surrounds the cane betv/een the joints, beginning at each joint, and gradually grow-, ing thinner the farther from the joint upwards, till the upper part between the joints appears entirely free from it, and assumes its bright yellow colour. It is a fine black powder, that mixes with the clammy exudations from the cane ; and as the fairness of the sugar is one BUG 748 SUG tymptom of its goodness, a small quantity of this crust must very much prejudice the com- modity. The sugar is obtained by the following pro- cess : The juice or liquor runs from the re- ceiver to the boiling-house, along a wooden gutter lined with lead. In the boiling-house, it is received into one of the copper pans or caldrons called clarifiers. Of these there are generally three ; and their dimensions are de- termined by the power of supplying them with liquor. There are water mills that will grind with great facility sufficient for thirty tyogsheads of sugar in a week. Methods of quick boiling cannot be dispensed with on plantations thus fortunately provided ; for otherwise the cane liquor would unavoidably become tainted before it could be exposed to the fire. The purest cane-juice will not remain twenty minutes in the receiver without fer- menting. Hence, clarifiers are sometimes seen of one thousand gallons each. But on planta- tions that, during crop time, make from fifteen to twenty hogsheads of sugar a-week, three clarifiers of three or four hundred gallons each are sufficient. The liquor, when clarified, may be drawn off at once, with pans of this size, and there is leisure to cleanse the vessels every time they are used. Each clarifier is furnished either with a siphon or cock for drawing off the liquor. It has a flat bottom, and is hung to a separate fire, each chimney having an iron slider, which, when shut, causes the fire to be extinguished through want of air*. As soon as the stream from the receiver has filled the clarifier with fresh liquor, and the fire is lighted, the temper, which is generally Bristol white-lime in powder, is stirred into it. This is done in order to neutralize the super- abundant acid, and to get rid of which is the greatest difficulty in sugar making. Alkali, or lime, generally effects this ; and at the same time part of it is said to become the basis of the sugar. Mr. Edwards affirms, that it affects both the smell and taste of the sugar. It falls to the bottom of the pans in a black insoluble matter, which scorches the bottom of the ves- sels, and cannot without difficulty be detached from them. But, in order that less of the * The clarifiers are generally placed in the middle or at one end of the boiling-house. When they are placed at oie end, the boiler called the tcac/te is placed at the other, and three boilers are usually ranged between them. The teache commonly holds from 70 to 100 gallons, and the boilers between the clarifiers and teache diminish in size from the first to the last. But when the clarifiers are in the middle, there is generally a set of three boilers on each side, which in effect form a double boiling-house. This arrangement is very ne- cessary on large estates. lime may be precipitated to the bottom, iittJ? more than half a pint of Bristol lime should be allowed to every hundred gallons of liquor, and Mr. Bousie's method of dissolving it in boiling water previous to mixing it with the cane-juice should be adopted f. As the force of the fire increases, and the liquor grows hot, a scum is thrown up, which is formed of the gummy matter of the cane, with some of the oil, and such impurities as the mucilage is able to entangle. The heat is now suffered to increase gradually till it nearly rises to the heat of bciling water. The liquor, however, must by no means be suffered to boil. When the scum begins to rise into blisters, which break into white froth, and generally appear in about forty minutes, it is known to be sufficiently heated. Then the damper is applied, and the fire extin- guished ; and, if circumstances will admit, the liquor after this is suffered to remain a full hour undisturbed. In the next place, it is carefully drawn off, either by a siphon, which draws up the clear fluid through the scum, or by means of a cock at the bottom. In either case, the scum sinks down without breaking as the liquor flows ; for its tenacity prevents any admixture. The liquor is re- ceived into a gutter or channel, which conveys it to the evaporating boiler, commonly called the grand copper ; and if produced at first from good and untainted canes, it will then appear almost transparent. In the grand or evaporating copper, which should be sufficiently large to receive the net contents of one of the clarifiers, the liquor is suffered to boil, and the scum as it rises is continually taken off by large scummers, till the liquor becomes finer and somewhat thicker. This operation is continued, till the subject is so redpced in quantity, that it may be con- tainedin the next or. second copper, into which it is then ladled. The liquor is now almost t Mr. Bousie, to whom, for his improve- ments in the art of sugar-boiling, the Assem- bly of Jamaica gave 1000/ , in a paper which he distributed among the members, recom- mends the use of vegetable alkali, or ashes of wood, such as pimento tree, dumb cane, fern tree, cashew, or logwood, as affording a better temper than quicklime. Afterward, however, he was convinced, that sugar formed on the basis of fixed alkaline salts never stands the sea, unless some earth is united to the salts. Such earih as approaches nearest to the basis of alum, Mr. Edwards thinks, would be most proper ; and it deserves to be inquired, how far a proper mixture of vegetable alkaline salts and lime might prove a better temper than either lime or alkaline salts alone. In some parts of Jamaica, where the canc-liqunr was exceedingly rich, Mr. Bousie made very good sugar without a particle of temper. SUG 749 SUG of the colour of Madeira wine. In the second copper the boiling and scumming are con- tinued ; and if the subject be not so clean as i? expected, lime water is thrown into it. This addition not only serves to give more temper, but likewise to dilute the liquor, which some- times thickens too fast to permit the feculen- cies to rise in the scum. When the froth in boiling arises in large bubbles, and is not much discoloured, the liquor is said to have a favourable appearance in the second copper. VFhen, in consequence of such scumming and evaporation, the liquor is again so reduced that it may be contained in the third copper, it is ladled into it, and so on to the last copper, which is called the teache. This arrangement supposes four boilers or coppers, besides the three clarifiers. In the teache the subject undergoes another evaporation, till it is sxipposed boiled enough to be removed from the fire. This operation .is usually called striking, i. e. ladling the liquor, which is now exceeding thick, into the cooler. The cooler, of which there are generally six, is a shallow wooden vessel, about eleven inches deep, seven feet in length, and from five to six feet wide. A cooler of this size holds a hogs- head of sugar. Here the sugar grains, i. e. as it cools it runs into a coarse irregular mass of imperfect crystals, separating itself from the melasses. From the cooler it is taken to the curing-house, where the melasses drains from it. But here it may be proper to notice the rule for knowing when the subject is fit to be ladled from the teache to the cooler. Many of the negro boilers, from long habit, guess accurately by the eye alone, judging by the appearance of the grain on the back of the ladle; but the practice generally adopted, is to judge by what is called the touch, i. e, taking up with the thumb a small portion of the hot liquor from the ladle, and, as the heat diminishes, drawing with the forefinger the liquid into a thread. This thread will sud- denly break and shrink from the thumb to the suspended finger, in different lengths, accord- ing as the liquor is more or less boiled. A thread of a quarter of an inch long generally determines the proper boiling height for strong muscovado sugar f. * It is necessary to observe in this place, that, in order to obtain a large-grained sugar, it must be suffered to cool slowly and gra- dually. If the coolers be too shallow, the grain is injured in a surprising manner. f The vessel called the teache probably de- rived its name from this practice of trying by the touch (tactio). Some years ago, John Procu- lus Baker, Esq. barrister at law, recommended to the public a method more scientific and cer- tain, in a treatise which he published in 1775, entitled. An Essay on the Art of making The curing-house is a large airy building; provided with a capacious melasses cistern, the sides of which are sloped and lined with terras, or boards. A frame of massy joist- work without boarding is placed over this cis- tern ; and empty hogsheads without headings are ranged on the joints of this frame. Eight or ten holes are bored in the bottoms of these hogsheads, and through each of the holes the stalk of a plaintain leaf is thrust six or eight inches below the joists, and long enough to stand upright above the top of the hogshead. Into these hogsheads the mass from the cooler is put, which is called potting ; and the me- lasses drains through the spongy stalk, and drops into the cistern, whence it is occasionally taken for distillation. In the space of three weeks, the sugar becomes tolerably dry and fair. It is then said to be cured, and the pro- cess is finished. Sugar thus obtained is called muscovado, and is the raw material whence the British sugar-bakers chiefly make their loaf or refined lump. There is another sort, which was for- merly much used in Great Britain for domes- tic purposes, and was generally known by the name of Lisbon sugar. In the West Indies it is called clayed sugar; and the process of making it is as follows : A quantity of sugar from the cooler is put into conical pots or pans, which the French call formes, with the points downward, having a hole about half an inch in diameter at the bottom for the melasses to drain through, but which at first is closed with a plug. As soon as the sugar in these pots is cool, and becomes a fixed body, which is known by the middle of the top falling in, the plug is taken out, and the pot placed over a large jar, intended to receive the syrup or melasses that drain from it. In this state it is left as long as the melasses continues to drop, when a stratum of clay is spread on the sugar, and moistened with water. This imperceptibly oozing through the pores of the clay, dilutes the melasses, in consequence of which more of it comes away than from sugar cured in the hogshead, and the sugar of course becomes so much whiter Muscovado Sugar. It is as follows : " Pro- vide a small thin pane of clear crown glass, set in a frame, which I would call a tryer ; on this drop two or three drops of the subject, one on the other, and carry your tryer out of the boiling-house into the air. Observe your subject, and more particularly whether it grain freely, and whether a small edge of melasses separate at the bottom. I am well satisfied, that a little experience will enable you to judge what appearance the whole skip will put on when cold, by this specimen, which is also cold. This -method is used by chemists, to try evaporated solutions of all other salts : it may seem therefore somewhat strange it has not been long adopted in the boiling-house." SUG 750 SUG and purer. According to Sloane, the process was first discovered in Brasil, by accident: " A hen," says he, " having her feet dirty, going over a pot of sugar, it was found under her feet to be whiter than elsewhere." The reason assigned why this process is not uni- versally adopted in the British sugar islands is this, that the water which dilutes and car- ries away the melasses, dissolves and carries with it so much of the sugar, that the differ- ence in quality does not pay for the difference in quantity. It is probable, however, that the French planters are of a different opinion; for upwards of four hundred of the planta- tions of St. Domingo have the necessary ap- paratus for claying, and actually carry on the system. Sugar is very soluble in water, and is a good medium for uniting that fluid with oily mat- ters. It is much used for domestic purposes, and appears on the whole to be a valuable and wholesome article of food, the uses of which are most probably restricted by its high price. This price may in a certain degree arise from the nature of the article, and its original cost ; but is no doubt in a great measure owing to the inhuman and wasteful culture by slaves, and the absurd principles of European coloni- zation, duties, drawbacks, and bounties, which have the effect to create unnatural monopolies, and to prevent commerce from finding its level. This is eminently the case with regard to our West India islands, and their produce. It appears that sugar has the property of rendering some of the earths soluble in water. This property was accidentally discovered by Mr. William Ramsay, of Glasgow. Being employed in making experiments on sugar, and happening to put some quicklime into a cold solution of it, he noticed, that it had acquired an uncommon caustic taste. Hence he concluded, that sugar possesses the property of dissolving a certain proportion of lime j and in order to ascertain its capacity in this respect, experiments were made upon this earth, together with strontites, magnesia, and barytes. Sugar, dissolved in water at the temperature of 50, is capable of dissolving one-half of its weight of lime. The solution of lime in sugar is of a beau- tiful white- wine colour, and has the smell of fresh-slacked quicklime. It is precipitated from the solution, by the carbonic, citric, tartaric, sulphuric, and oxalic acids ; and it is decomposed, by double affi- nity, by caustic and carbonated potash and soda, the citrate, tartrate, and oxalate of pot- ash, &c. An equal weight of strontia, with the sugar employed, is capable of being dissolved at the temperature of 212, and of being retained in solution by the sugar at 50 of Fahrenheit. On exposing the crystals, which had fallen down during thfe cooling of the liquid, to the air of the atmosphere, they attracted carbonic acid, and effloresced. The solution of strontia in sugar is of a fine white-wine colour, and, like that of lime, has a peculiar caustic smell. This earth is pre- cipitated by caustic and carbonated potash and soda ; also by the carbonic, citric, tartaric, sulphuric, and oxalic acids ; and it is decom- posed, by compound affinity, by the carbon- ates of potash and soda ; also by the citrate, tartrate, and oxalate of potash. The solution of magnesia in syrup, like those of lime and strontia, was of a pure white colour, and had no sensible variation in smell or taste from the common solution of sugar, farther than that the sweet seemed much im- proved, and was softer and more agreeable to the palate, as if it were entirely freed from the earthy taste which unrefined sugar frequently has. On its remaining at rest for some months in a bottle well corked, the magnesia appears to be entirely separated. Very little alumina is dissolved by a solu- tion of sugar, when fresh precipitated earth is presented to it, either in the cold or hot state. The union of sugar with the alkalis has been long known ; but this is rendered more strikingly evident, by carbonated potash or soda, for instance, decomposing the solutions of lime and strontia in sugar, by double affinity. The power possessed by tartaric acid of pre- venting the precipitation of iron and some other metals from their muriatic solution, is well known from the observations of M. Rose and others. A similar effect is produced by sugar, according to M. Peschier, if the mix- ture be boiled, but not otherwise. Ann. de Cltim. et Phi/s. xxxi. 197' In making solutions of unrefined sugar for culinary purposes, a gray-coloured substance is found frequently precipitated. It is pro- bable, that this proceeds from a superabund- ance of lime, which has been used in clarifying the juice of the sugar-cane at the plantations abroatl. Sugar with this imperfection is known among the refiners of this article by the name of -weak. And it is justly termed so, the pre- cipitated matter being nothing but lime which has attracted carbonic acid from the sugar, (of which there is a great probability), or from the air of the atmosphere. A bottle in which I had kept a solution of lime in sugar for at least four years, closely corked, was entirely incrusted with a yellowish-coloured matter, which on examination was found to be entirely carbonate of lime. In the ordinary refining of raw sugars, from twenty to thirty-five per cent, of melasses are separated, of which a considerable part, pro- bably two-thirds, are formed by the high heat used in the concentration of the syrup. Various plans have been contrived to diminish this pro- duction of melasses. One of these consisted SUG 751 SUG in surrounding the sugar boiler with oil or steam at a high temperature, instead of ex- posing it to a naked fire. In a second, the boiler is covered at top, and by means of an air-pump the atmospheric pressure is removed, so as to favour ebullition, and rapid evapora- tion, at moderate heats. The celebrated chemist, Mr. Howard, took out a patent for this plan, which is undoubt- edly the most scientific and productive of any ; but requires superior skill and very minute attention in the manufacturer. No blood is used for clarification. This is accomplished by a system of most ingenious canvass filters, aided by the intermixture with the syrup of a small quantity of pasty gypsum and alumina, made by saturating a solution of alum with quicklime. In the final purification, the base of the inverted sugar- cone is covered with a stratum of very pure saturated syrup, instead of moist pipe-clay. The third method is founded on the pro- perty which animal charcoal (bone-black) pos- sesses, of destroying vegetable colouring mat- ter. Perhaps the combination of the last two modes promises the best results. A fourth process for refining sugar is that of Mr. Daniel Wilson, for which a patent was granted. The specification is in the 34th vol. of the Repertory, p. 134. The pan is to be charged with strong lime- water, the sugar added, and the fire set in the usual manner. For every hundred weight of sugar used, a solution is to be made of four ounces of sulphate of zinc, in as small a quan- tity of water as will dissolve it. When the sugar in the pan is melted, the solution of sul- phate of zinc is added, and the whole well stirred. The oxide of zinc combines with the extractive matter, tannin and gallic acid, and renders them insoluble, while the sulphuric acid, in combination with the lime, becomes also insoluble. When raw sugar contains much acid, and a strong grain is required, take one ounce of lime in powder for every four ounces of sulphate of zinc, and as much water as will form a milk of lime, which is added to the solution of sugar in the pan, about five minutes after the solution of sul- phate of zinc has been added. This purifica- tion of sugar by separating impurities che- mically combined with it, is employed with much advantage in conjunction with the patent filtering apparatus invented by Mr. John Su- therland. The solution of sugar brought to the boiling point is run through the filter, and afterwards boiled to a proof. Mr. Wilson boils the syrup in a pan, having a coil of tinned copper or pure tin tubes placed along its bottom and sides, through which a constant stream of strongly heated oil, or other fatty matter, is made to pass. The oxide of zinc precipitated previously by adding a solution of the salt to lime water, is also recommended, n.s well as the oxide of tin. Mr. KirchofF, an ingenious Russian die- mist, accidentally discovered, that starch is convertible into sugar, by being boiled for some time with a very dilute sulphuric acid. Saussure showed, that 100 parts of starch yield 110 of sugar. He concluded, that this sugar is merely a compound of water and starch. According to his analysis, starch con- sists of Oxygen, 56-87 Carbon, 37-29 Hydrogen, 6-84 100-00 Sugar of grapes, according to the same chemist, is composed of, Oxygen, 56-51 Carbon, 36-71 Hydrogen, 6-78 100-00 Common sugar has been analyzed by many eminent chemists. The following is a general view of the results : G. Lussac and Berzelius, Prout. Thenard. Mean of 3. Oxygen, 50-63 49-856 53-35 Carbon, 42-4? 43-265 39-99 Hydrogen, 6-90 6-879 6-66 100-00 100-000 100-GO By my ultimate analysis of sugar, its con- stituents are, Carbon, 43-38 5 atoms 45-4 Hydrogen, 6-29 4 6-1 Oxygen, 50-33 4 48-5 10000 100-0 Phil Trans. 1822. For a view of the proportions of the consti- tuents referred to equivalent primes or vo- lumes, see FERMEXTATION, column 4. It may be observed that Dr. Prout's experimental results agree with M. Gay Lussac's theory, of sugar being a compound of 40 parts of carbon -j-.fiO of water, or its elements. By Berzelius's analysis, starch consists of, Oxygen 49-5 Carbon, 43-5 Hydrogen, 70 100-0 The abstraction of a little hydrogen and carbon would convert it into sugar. But no carbonic acid or other gas is extricated during the conversion, according to Vogel's experi- ments. I find that potatoes digested with dilute sulphuric acid, yield sugar cheaply and abundantly. The acid is afterwards removed by chalk ; and the strained liquor left to re- pose, after due evaporation, affords crystals of sugar. From starch sugar, good beer has been made. I would recommend potatoes for this purpose. They are washed, grated down, and treated with the dilute acid for a day or two at a temperature of 212. SUG 752 SUG M. Braconnot has recently extended our views concerning the artificial production of sugar and gum. Sulphuric acid (sp. gr. 1-827) mixed with well dried elm dust, became very hot, and on being diluted with water, and neutralized with chalk, afforded a liquor which became gummy on evaporation. Shreds of linen triturated in a glass mortar, with sulphuric acid, yield a similar gum. Nitric acid has a similar power. If the gummy matter from linen be boiled for some time with dilute sulphuric acid, we obtain a crys- tallizable sugar, and an acid, which M. Braconnot calls the vegeto-sulphuric acid. The conversion of wood also into sugar will no doubt appear remarkable ; and when persons not familiarized with chemical speculations are told, that a pound weight of rags can be converted into more than a pound weight of sugar, they may regard the statement as a piece of pleasantry, though nothing, says M. Braconnot, can be more real. Silk is also convertible into gum by sulphuric acid. Twelve grammes of glue, reduced to powder, were digested with a double weight of concentrated sulphuric acid without artificial heat. In twenty hours the liquid was not more coloured than if mere water had been employed. A decilitre of water was then added, and the whole was boiled for five hours, with renewal of the water, from time to time, as it wasted. It was next diluted, saturated with chalk, filtered, and evaporated to a syrupy consistence, and left in repose for a month. In this period a number of granular crystals had separated, which adhered pretty strongly to the bottom of the vessel, and had a very decided saccharine taste. This sugar crystallizes much more easily than cane sugar. The crystals are gritty under the teeth, like sugar-candy ; and in the form of flattened prisms or tabular groupes. Its taste is nearly as saccharine as grape sugar ; its solubility in water scarcely exceeds that of sugar of milk. Boiling alcohol, even when diluted, has no action on this sugar. By distillation it yields ammonia, indicating the presence of azote. This sugar combines intimately with nitric acid, without sensibly decomposing it, even with the assistance of heat, and there results a peculiar crystallized acid, to which the name mtro-saccharine has been given. Annalcs de Chimie, xii. or TUlocK's Magazine, vol. 55 and 56. The varieties of sugar are; cane sugar, maple sugar, liquid sugar of fruits, sugar of fi^s, sugar of grapes, starch sugar, the mushroom sugar of Braconnot, manna, sugar of gelatin, sugar of honey, and sugar of diabetes. Sugar of grapes does not affect a peculiar form. It is deposited, from its alcoholic solution, in small grains, which have little consistence, are grouped together, and which constitute tubercles, similar' to those of cauli- flowers. When put in the mouth, it produces at first a sensation of coolness, to which suc- ceeds a saccharine taste, not very strong. Hence, to sweeten to an equal degree the same quantity of water, we must employ two and a half times as much sugar of grapes as of that of the cane. In other respects, it possesses all the properties of cane sugar. Its extraction is very easy. The expressed juice of the grapes is composed of water, sugar, mucilage, bitartrate of potash, tartrate of lime, and a small quantity of other saline matters. We pour into it an excess of chalk in powder, or rather of pounded marble. There results, especially on agitation, an effervescence, due to the unsaturated tartaric acid. The liquor is then clarified with whites of eggs or blood. It is next evaporated in copper pans, till it marks a density of 1.32 at the boiling temperature. It is now allowed to cool. At the end of some days, it concretes into a crystalline mass, which, when drained, washed with a little cold water, and strongly compressed, constitutes sugar. In the south of France, where this operation was some years back carried on on the great scale, to prevent fermentation of the must, there was added to this a little sulphate of lime, or it was placed in tuns, in which sulphur matches had been previously made to burn. The oxygen of the small quantity of air left in the tuns being thus abstracted by the sul- phurous acid, fermentation did not take place. By this means, the must can be preserved a considerable time ; whereas, in the ordinary way, it would lose its saccharine taste at the end of a few days, and become vinous. Must thus treated is said to be muted. The syrup was evaporated to the density of only 1-285 Proust, Ann. de CIdmic, Ivii. 131. ; and the Collection of Memoirs published by Parmcntier in 1813. It is this species of sugar which is obtained from starch and woody fibre by the action of dilute sulphuric acid. Sugar of diabetes has sometimes the sweeten- ing force of sugar of grapes; occasionally much less. Braconnot's mushroom sugar is much less sweet than that of the cane. It crystallizes with remarkable facility, forming long quad- rilateral prisms with square bases. It yields alcohol by fermentation. All honeys contain two species of sugar ; one similar to sugar of the grape, another like theuncrystallizable sugar of the cane (m classes). These combined, and mingled in different proportions with an odorant matter, constitute the honeys of good quality. Those of inferior quality contain, besides, a certain quantity of wax and acid : the honeys of Britanny contain even an animal secretion (couvain) to which they owe their putrescent quality. A slight washing with a little alcohol separates the uncrystallizable sugar, and leaves the other, SUE 753 SUL which may be purified by washing with a very little more alcohol. " The relation," says Dr. Prout, " which exists between urea and sugar seems to ex- plain in a satisfactory manner the phenomena of diabetes, which may be considered as a depraved secretion of sugar. The weight of the atom of sugar is just half that of the weight of the atom of urea ; the absolute quantity of hydrogen in a given weight of both is equal ; while the absolute quantities of carbon and oxygen in a given weight of sugar are precisely twice those of urea." The constituents of these two bodies and lithic acid are thus expressed by that ingenious philosopher. ELEMENTS. Hydrogen .... Carbon UREA. SUGAR. LITHIC ACID. No. Per Atom. Per Cent. No. Per Atom. Per Cent. No. Per Atom. Per Cent. 2 1 1 1 2-5 7-5 10-0 17-5 6-66 19-99 26-66 46-66 1 1-25 7-50 10-00 6-66 39-99 53-33 1 2 1 1 1-25 15-00 10-00 17-50 2-85 34-28 22-85 40-00 Azote 5 37.5 100-00 3 18-75 100-00 5 43-75 100-00 The above compounds appear to be formed by the union of more simple compounds, as sugar, of carbon and water; urea, of car- buretted hydrogen and nitrous oxide ; lithic acid, of cyanogen and water, &c. whence it is inferred, that their artificial formation falls within the limits of chemical operations. SUGAR or LEAD. Acetate of lead. See LEAD. SULPHATES. Definite compounds of sulphuric acid with the salifiable bases. See ACID (SULPHTTHIC), and the respective bases. SULPHATO-TRI CARBONATE or LEAD. A new mineral, found at Leadhills, whose peculiar nature was first pointed out by Mr. Brooke. Stromeyer has since confirmed Mr. Brooke's statement of its composition, as follows : Carbonate of lead a - . * 72-7 Sulphate of lead * 27-3 SULPHITES. Definite compounds of sulphurous acid with the bases. SULPHUR. Of native or prismatic sul- phur there are two species, the common and volcanic ; the former is of two kinds, compact and earthy sulphur. 1. Compact common sulphur. Colour sulphur-yellow, and yellow of other shades. Massive, disseminated, and crystallized. Its primitive figure is a pyramid of 107 19'; and 84<> 24' ; basis = 102 41'. The secondary figures are, the primitive variously truncated or acuminated, and delicate acicular crystals. Shining or glimmering. Cleavage prismatic and axifrangible. Fracture uneven. Trans- lucent. Refracts double. Harder than talc. Brittle. When rubbed, it exhales a faint sulphureous smell, and becomes resino-electric. Sp. gr. 1-9 to 2-1. It occurs in considerable abundance in primitive mountains, in a state of combination with metals, forming the different genera of pyrites, glance, and blende. In secondary mountains it is more abundant in the pure uncombined state. It is found in the island of Iceland, associated with gypsum ; or in crusts investing alluvial substances. Very superb specimens of crystallized sulphur are found at Conil near Cape Trafalgar. It occurs abundantly in Sicily, at Urbino in the Papal States, in Arragon in Spain, and Lauenstein in Hanover. 2. Earthy common sulphur. Colour pale straw-yellow Massive and disseminated. Dull. Fracture fine earthy. Opaque. Does not soil. Soft to friable. It occurs in drusy cavities in flint, and along with the compact varieties in gypsum, and other rocks. 2. Volcanic sulphur. Colour pale sulphur- yellow. Massive, imitative, and crystalJized in pyramids. Glistening, inclining to ada- mantine. Fracture uneven. Slightly trans- lucent. It occurs abundantly at Solfaterra in the neighbourhood of Vesuvius, and in Ice- land. Jameson. SULPHUR. A simple inflammable body, of great importance in chemistry and the arts, To the properties above mentioned we shall here add, that its fusing point is about 220 F., before which temperature it begins to evaporate. At 560 it takes fire in the open air, and burns with a pale blue flame. When kept melted in an open vessel for some time, about 300 F., it becomes thick and viscid; and if it be then poured into a basin of water, it appears of a red colour, and ductile like wax. In this state it is used for taking im- pressions of seals or medals. Its sp. gr. is said to be increased from 1-99 to 2-325- This change is not owing to oxidation, for it takes place in close vessels. When a roll of sulphur is suddenly seized in a warm hand, it crackles, and sometimes falls in pieces. This is owing to the unequal action of heat, on a body which conducts that 3c SUL 754 SUL power slowly, and which has little eoliesion. If a mass of sulphur be melted in a crucible, and after the surface begins to concrete, if the liquid matter below be allowed to run out, fine acicular crystals of sulphur will be obtained. Sulphur is insoluble in water ; but in small quantity in alcohol and ether, and more largely in oil. Sulphur combines with oxygen in four definite proportions, constituting an interesting series of acids. See ACID (SULPHURIC). From these combinations it is inferred, that the prime equivalent of sulphur is 2 ; and the density of its vapour is 1.111 that of oxygen gas. Sulphur combines readily with chlorine. This compound was first made by Dr. Thom- son, who passed chlorine gas through flowers of sulphur. It may be made more expedi- tiously by heating sulphur in a retort con- taining chlorine. The sulphur and chlorine unite, and form a fluid -substance, which is volatile below 200 F., and distils into the cold part of the retort. This substance, seen by reflected light, appears of a red colour, but is yellowish-green when seen by transmitted light. It smokes when exposed to air, and has an odour somewhat resembling that of sea-weed, but much stronger; it affects the eyes like the smoke of peat. Its taste is acid, hot, and bitter. Its sp. gr. is 1.7- It does not redden perfectly dry paper tinged with litmus; when it is agitated in contact with water, the water becomes cloudy from* the appearance of sulphur, and strongly acid,'fand it is found to contain oil of vitriol. According to Sir H. Davy's experiments, 1 grains of pure sulphur absorb nearly 30 cubic inches of chlorine, so that the compound contains about 2 sulphur to 4.5 chlorine, or a prime equivalent of each. The compound formed in the manner above described cannot be made to unite to more chlorine; but it can dissolve a considerable portion of sulphur by heat, and becomes of a tawny-yellow colour. Iodide of sulphur is easily formed by mix- ing the two ingredients in a glass tube, and exposing them to such a heat as melts the sulphur. It is grayish-black, and has a radiated structure like that of sulphuret of antimony. When distilled with water, iodine is disengaged. Sulphur and hydrogen combine. Their union may be effected, by causing sulphur to sublime in dry hydrogen in a retort. There is no change of volume ; but only a part of the hydrogen can be united with the sulphur in this mode of operating. The usual way of preparing sulphuretted hydrogen is to pour a dilute sulphuric or muriatic acid on the black sulphuret of iron or antimony in a retort. For accurate ex- periments it should be collected over mercury, it takes fire when a lighted taper is brought in contact with it, and bums with a pale blue flame, depositing sulphur. Its smell is ex- tremely fetid, resembling that of rotten eggs. Its taste is sour. It reddens vegetable blues. It is absorbable by water, which takes up more than an equal volume of the gas. Its sp. gr. according to MM. Gay Lussac and Thenard, is to that of air as 1.1912 to 1.0. From Sir II. Davy's experiments, it would appear to be a little less, but he is inclined to adopt the results of the French chemists, rather than his own, as their gas was weighed in larger quantity, and dried. Notwithstanding this preference of other experiments to his own, we must prefer a number nearer to Sir H. Davy's than M. Gay Lussac's. Its true sp. gr. is 1.1805. 100 cubic inches weigh 36.006 ; and it consists of 1 volume vapour of sulphur = 1.1111 -+- 1 volume of hydrogen = 0.0694 = 1.1805; or a prime equivalent of each = 2.125. If platina wires be ignited in it, by the voltaic apparatus, it is rapidly decomposed. Sulphur is deposited, and an equal volume of hydrogen remains. The same change is effected more slowly by electric sparks. M. Berthier recommends the following pro- cess for procuring pure sulphuretted hydrogen at an economical rate : powdered common iron pyrites is to be mixed with half its weight of dry carbonate of soda, and heated red hot in a crucible ; a fused sulphuret of sodium and iron is obtained, which may be poured out on a stone to cool. It is then a homo- geneous deep-yellow coloured mass, having a lamellar fracture. It absorbs much water, forming with it a black paste, which, when acted on by sulphuric or muriatic acid, in- stantly yields abundance of sulphuretted hydrogen ; leaving a black sulphuret of iron, which, by the application of acid and heat, will yield a second portion of the gas. Sulphuret of lime, made by decomposing the sulphate at a high heat, with one- fifth of its weight of charcoal, yields 46.8 per cent. of sulphuretted hydrogen, when acted on with dilute muriatic acid. Ann. de Chimte, xxiv. 271. .When a few drops of fuming nitric acid are put into a flask filled with pure sulphuretted hydrogen, the hydrogen is oxidized by the nitric acid, and the sulphur is disengaged in a solid form. If the flask be closed with the finger, so that the gas which becomes heated cannot escape, its temperature is raised so much as to produce combustion with a beautiful flame, and a slight detonation which foices the finger from the mouth of the flask. This experiment may be made without the least danger, with a flask containing four or five cubical inches of gas. Bcrzelius. Of all the gases, sulphuretted hydrogen is perhaps the most deleterious to animal life. A greenfinch, plunged into air, which contains only YjSyj of its volume, perishes instantly. SUL 755 SUL A dog of middle etee is destroyed In afr that contains -^fa ; and a horse would fall a victim to an atmosphere containing -pfa. Dr. Chaussier proves, that to kill an ani- mal, it is sufficient to make the sulphuretted hydrogen gas act on the surface of its body, when it is absorbed by the inhalants. He took a bladder having a stop- cock at one end, and at the other an opening, into which he introduced the body of a rabbit leaving its head outside, and securing the bladder air- tight round the neck by adhesive plaster. He then sucked the air out of the bladder, and replaced it by sulphuretted hydrogen gas. A young animal in these circumstances usually perishes in 15 or 20 minutes. Old rabbits resist the poison much longer. When potassium or sodium is heated, merely to fusion, in contact with sulphuretted hydrogen, it becomes luminous, and burns with extrication of hydrogen, while a metallic sulphuret remains, combined with sulphu- retted hydrogen, or a sulphuretted hydro- sulphuret. Sulphuretted hydrogen combines with an equal volume of ammonia, and unites to alkalis and oxides, so that it has all the characters of an acid. These compounds are called hydrosulphurets. All the hydrosulphurcts, soluble in water, have an acrid and bitter taste, and, when in the liquid state, the odour of rotten eggs. All those which are insoluble are, on the contrary, insipid, and without smell. There are only two coloured hydrosulphurets, that of iron, which is black, and of antimony, which is chestnut-brown . All the hydrosulphurets are decomposed by the action of fire. That of magnesia is trans- formed into sulphuretted hydrogen and oxide of magnesium ; those of potash and soda, into sulphuretted hydrogen, hydrogen, and sul- phuretted alkalis ; those of manganese, zinc, iron, tin, and antimony, into water and me- tallic sulphurets. When we put in contact with the air, at the ordinary temperature, an aqueous solution of a hydrosulphuret, there results, in the space of some days, 1st, water, and a sulphuretted hydrosulphuret, which is yellow and soluble ; 2d, water, and a colourless hydrosulphite, which, if its base be potash, soda, or ammo- nia, remains in solution in the water; but which falls down in acicular crystals, if its base be barytes, strontia, or lime. The acids in general combine with the base of the hydrosulphurets, and disengage sul- phuretted hydrogen with a lively effervescence, without any deposition of sulphur, unless the acid be in excess, and be capable, like the nitric and nitrous acid, of yielding a portion of its oxygen to the hydrogen of the sulphu- retted hydrogen. The hydrosulphurets of potash, soda, am- monia, lime, and magnesia, are prepared di- rectly, by transmitting an excess of sulphu- retted hydrogen gas through these bases, dis- solved or diffused in water. The composition of the hydrosulphurets is such, that the hydrogen of the sulphuretted hydrogen is to the oxygen of the oxide in the same ratio as in water. Hence, when we calcine the hydrosulphurets of iron, tin, &c. we convert them into water and sulphurets. Hydrosulphuret of potash crystallizes in four-sided prisms, terminated by four-sided pyramids. Its taste is acrid and bitter. Ex- posed to the air, it attracts humidity, absorbs oxygen, passes to the state of a sulphuretted hydrosulphuret, and finally to that of a hy- drosulphite. It is extremely soluble in water. Its solution in this liquid occasions a per- ceptible refrigeration. Subjected to heat, it evolves much sulphuretted hydrogen, and the hydrosulphuret passes to the state of a sub- hydrosulphuret Hydrosulphuret of soda crystallizes with more difficulty than the preceding. Hydrosulphuret of ammonia is obtained by the direct union of the two gaseous constituents in a glass balloon, at a low temperature. As soon as the gases mingle, transparent white or yellowish crystals are formed. When a mere solution of this hydrosulphuret is wished for medicine or analysis, we pass a current of sulphuretted hydrogen through aqueous am- monia till saturation. The pure hydrosulphuret is white, trans- parent, and crystallized in needles or fine plates. It is very volatile. Hence, at ordi- nary temperatures, it gradually sublimes into the upper part of the phials in which we preserve it We may also by the same means separate it from the yellow sulphuretted hy- drosulphuret, with which it is occasionally mixed. When exposed to the air, it absorbs oxygen, passes to the state of a sulphuretted hydrosulphuret, and becomes yellow. When it contains an excess of ammonia, it dissolves speedily in water, with the production of a very considerable cold. Sub-hydrosulphttrct of Inrytcs is prepared by dissolving, in five or six parts of boiling water, the sulphuret of the earth obtained by igniting the sulphate with charcoal. The solution being filtered while hot, will deposit, on cooling, a multitude of crystals, which must be drained, and speedily dried by pres- sure between the folds of blotting paper. It crystallizes in white scaly plates. It is much more soluble in hot than in cold water. Jts solution is colourless, and capable of absorb- ing, at the ordinary temperature, a very large quantity of sulphuretted hydrogen. 8uJ)-hydrosulphuret of strontitex crystallizes in the same manner as the preceding. The crystals obtained in the same way must be dissolved in water; and the solution being exposed to a stream of sulphuretted hydrogen, and then concentrated by evaporation in a 3c2 SUL 756 SUL retort, will afford, on cooling, crystals of pure sub-hydrosulphuret. Hydrosulphurets of lime and magnesia have been obtained only in aqueous solutions. The metallic hydrosulphurets of any practical importance are treated of under their respective metals. When we expose sulphur to the action of a solution of a hydrosulphuret, saturated with sulphuretted hydrogen, as much more sul- phuretted hydrogen is evolved as the tem- perature is more elevated. But when the solution of hydrosulphuret, instead of being saturated, has a sufficient excess of alkali, it evolves no perceptible quantity of sulphuretted hydrogen, even at a boiling heat ; although it dissolves as much sulphur as in its state of saturation. It hence follows, 1st, That sul- phuretted hydrogen, sulphur, and the alkalis, have the property of forming very variable triple combinations ; 2d, That all these com- binations contain less sulphuretted hydrogen than the hydrosulphurets ; and, 3d, That the quantity of sulphuretted hydrogen is inversely as the sulphur they contain, and reciprocally. These compounds have been called, in general, sulphuretted hydrosulphurets; but the name of hydrogenated sulphurets is more particularly given to those combinations which are saturated with sulphur at a high temperature, because, by treating them with acids, we precipitate a peculiar compound of sulphur and hydrogen, of which we shall now treat. Thi;s compound of hydrogen and sulphur, the proportions of the elements of which have not yet been accurately ascertained, is also called hydruret of sulphur. It is formed by putting flowers of sulphur in contact with nas- cent sulphuretted hydrogen. With this view, we take an aqueous solution of the hydroge- nated sulphuret of potash, and pour it gra- dually into liquid muriatic acid, which seizes the potash, and forms a soluble salt, whilst the sulphur and sulphuretted hydrogen unite, fall down together, collecting by degrees at the bottom of the vessel, as a dense oil does in water. To preserve this hydruret of sulphur, we must fill with it a phial having a ground stopper, cork it, and keep it inverted in a cool place. We may consider this substance either as a combination of sulphur and hydrogen, or of sulphur and sulphuretted hydrogen; but its properties, and the mode of obtaining it, render the latter the more probable opinion. The proportion of the constituents is not known. The most interesting of the hydrogenated sulphurets is that of ammonia. It was dis- covered by the Hon. Robert Boyle, and called his fuming liquor. To prepare it, we take one part of muriate of ammonia and of pulverized quicklime, and half a part of flowers of sul- phur. After mixing them intimately, we introduce the mixture into an earthen or glass retort, taking care that none of it remains in the neck. A dry cooled receiver is connected to the retort by means of a long adopter-tube. The heat must be urged slowly almost to red- ness. A yellowish liquor condenses in the receiver, which is to be put into a phial with its own weight of flowers of sulphur, and agitated with it seven or eight minutes. The greater part of the sulphur is dissolved, the colour of the mixture deepens remarkably, and becomes thick, constituting the hydrogenated sul- phuret. The distilled liquor diffuses, for a long time, dense vapour in a jar full of oxygen or common air ; but scarcely any in azote or hy- drogen ; and the dryness or humidity of the gases makes no difference in the effects. It is probably owing to the oxygen converting the liquor into a hydrogenated sulphuret, or per- haps to the state of sulphite, that the vapours appear. Hydrogenated sulphurets are frequently called hydroguretted sulphurets. Sulphur combines with carbon, forming an interesting compound, to which the name of sulphuret of carbon is sometimes given. 1 have described it under the title CARBURE T OF SULPHUR. For the combinations of sulphur and phosphorus, see the latter ar- ticle. SULPHURETS OF ALKALIS AND EARTHS. Heretofore these were reckoned compounds of the alkalis and earths themselves with sulphur, that is, sulphuretted oxides ; but M. Berthier has proved that they are all true metallic sulphurets. He reduces the sul- phates of alkalis into sulphurets, not by mix- ing them directly with powdered charcoal, but by placing them in the centre of a crucible, thickly lined with charcoal, covering them 'with the same substance, and after having luted on a cover, heating the whole in a fur- nace. In this way the sulphates are reduced by cementation. All are reducible at a white heat, and where the sulphuret is fusible very quickly. In this way not only are pure sul- phurets formed, but the result may be col- lected without the smallest loss, its weight ascertained, and the weight of oxygen evolved accurately estimated. If a sulphate of barytes, strontites, or lime be thus reduced to a sulphuret, and weighed, the loss will be found to equal exactly the quantity of oxygen contained in the base and the acid. If the sulphuret be dissolved in dilute muriatic acid, nothing will be liberated but pure sulphuretted hydrogen ; no sulphur will be set free, nor any acid containing sul- phur and oxygen formed ; finally, if a portion of the sulphuret be heated in a crucible of silver, with nitre equal to three or four times its weight, the sulphate regenerated will correspond with the quantity of sulphuret employed, and will contain neither acid nor base in excess. These three experiments prove that the sulphuret produced-contains no oxygen, and consequently SWE 757 SWE th.it the base is in the metallic state. Journ. des Mines, vii. 421. SULPHURETTED CHYAZIC ACID. See ACID (SULPHUROPRUSSIC). SULPHURIC ACID. See ACID (SUL- PHURIC). SULPHUROUS ACID. See ACID (SUL- PHUROUS). SUMACH. Common sumach (rhus con- aria) is a shrub that grows naturally in Syria, Palestine, Spain, and Portugal. In the two last, it is cultivated with great care. Its shoots are cut down every year quite to the root ; and, after being dried, they are reduced to powder by a mill, and thus prepared for the purposes of dyeing and tanning. The sumach culti- vated in the neighbourhood of Montpellier is called redoid, or roudou. Mr. Hatchett found, that an ounce contains about 78 or 79 grains of tannin. Sumach acts on a solution of silver just as galls do ; it reduces the silver to its metallic state, and the reduction is favoured by the ac- tion of light. Of all astringents sumach bears the greatest resemblance to galls. The precipitate, how- ever, produced in solutions of iron by an infu- sion of it, is less in quantity than what is ob- tained by an equal weight of galls ; so that in most cases it may be substituted for galls, the price of which is considerable, provided we proportionally increase its quantity. Sumach alone gives a fawn colour, inclining to green ; but cotton stuffs, which have been impregnated with printer's mordant, that is, acetate of alumina, take a pretty good and very durable yellow. An inconvenience is experi- enced in employing sumach in this way, which arises from the fixed nature of its co- lour ; the ground of the stuff does not lose its colour by exposure on the grass, so that it be- comes necessary to impregnate all the stuff with different mordants, to vary the colours, without leaving any part of it white. SUPERSALT. A compound of an acid and base, in which the acid is in excess. See SUBSALT. SUPERSALTS. Salts with excess of acid. SURTURBRAND. Fibrous brown coal or bituminous wood, so called in Iceland, where it occurs in great quantities. SWAMP ORE. Indurated bog iron ore. SWEAT. When the temperature of the body is much increased, either by being ex- posed to a hot atmosphere or by violent exer- cise, the perspired vapour not only increases in quantity, but even appears in a liquid form. This is known by the name of sweat. Beside water, it cannot be doubted that car- bon is also emitted from the skin ; but in what state, the experiments hitherto made do not enable us to decide. Mr. Cruickshanks found, that the air of the glass vessel in which his hand and foot had been confined for an hour, contained carbonic acid gas ; for a candle burned dimly in it, and it rendered lime water turbid. And Mr. J urine found that air which had remained for some time in contact with the skin, consisted almost entirely of carbonic acid gas. The same conclusion may be drawn from the experiments of Ingenhousz and M il- ly. Trousset has lately observed, that air was separated copiously from a patient of his, while bathing. Beside water and carbon, or carbonic acid gas, the skin emits also a particular odorous substance. That every animal has a peculiar smell is well known : the dog can discover his master, and even trace him to a distance by the scent. A dog, chained up several hours after his master had set out on a journey of some hundred miles, followed his footsteps by the smell. But it is needless to multiply in- stances of this fact ; they are too well known to every one. Now this smell must be owing to some peculiar matter, which is constantly emitted ; and this matter must differ somewhat, either in quantity or some other property, as we see that the dog easily distinguishes the in- dividual by means of it. Mr. Cruickshanks has made it probable, that this matter is an oily substance ; or at least that there is an oily substance emitted by the skin. He wore repeatedly, night and day for a month, the same under waistcoat of fleecy hosiery, during the hottest part of the summer. At the end of this time he always found an oily substance accumulated in considerable masses on the nap of the inner surface of the waistcoat, in the form of black tears. When rubbed on paper it rendered it transparent, and hardened on it like grease. 1 1 burned with a white flame, and left behind it a charry residuum. Berthollet has observed the perspiration acid ; and he has concluded, that the acid which is present is the phosphoric ; but this has not been proved. Fourcroy and Vauque- lin have ascertained, that the scurf which col- lects upon the skins of horses consists chiefly of phosphate of lime, and urea is even some- times mixed with it. According to Thenard, however, who has lately endeavoured more particularly to ascer- tain this point, the acid contained in sweat is the acetous ; which, he likewise observes, is the only free acid contained in urine and in milk, this acid existing in both of them when quite fresh. His account of his examination of it is as follows : The sweat is more or less copious in dif- ferent individuals; and its quantity is per- ceptibly in the inverse ratio of that of the urine. All other circumstances being similar, much more is produced during digestion than during repose. The maximum of its produc- tion appears to be twenty-six grains and two- thirds in a minute ; the minimum nine grains, troy weight. It is much inferior, however, to the pulmonary transpiration ; and there is TAL 758 TAL likewise a great dffibrence between Iheir nature and manner of formation. The one is a pro- duct of a particular secretion, similar in some sort to that of the urine ; the other, com- posed of a great deal of water and carbonic acid, is the product of a combustion gradually effected by the atmospheric air. The sweat, in a healthy state, very sensibly reddens litmus paper or infusion. In certain diseases, and particularly in putrid fevers, it is alkaline ; yet its taste is always rather sa- line, and more similar to that of salt than acid. Though colourless, it stains linen. Its smell is peculiar, and insupportable when it is concentrated, which is the case in particular during distillation. But before he speaks of the trials to which he subjected it, and of which he had occasion for a great quantity, he describes the method he adopted for pro- curing it, which was similar to that of Mr. Cruickshanks. Human sweat, according to M. Thenard, is formed of a great deal of water ; free ace- tous acid ; muriate of soda ; an atom of phos- phate of lime, and oxide of iron ; and an in. appreciable quantity of afllmal matte*, which approaches much nearer to gelatin than to any other substance. SWINESTONE. A variety of compact lucullite, a sub-species of limestone. SYLVANITE. Native tellurium. SYLVIUS (SALT or) or FEBRIFUGE (SALT OF ). Muriate of potash. SYNOVIA. Within the capsular liga- ment of the different joints of the body there is contained a peculiar liquid, intended evi- dently to lubricate the parts, and to facilitate their motion. This liquid is known among anatomists by the name of synovia. From the analysis of M. Margueron, it appears that synovia is composed of the fol- lowing ingredients : 11-86 fibrous matter 4-52 albumen 1-75 muriate of soda 71 soda 70 phosphate of lime 80-46 water 100-00 T ABASHEER. The silica which is found in the hollow stem of the bamboo is so named. Its optical properties are peculiar. They have been described by Dr. Brewster, Phil. Trans. 1819. TABULAR SPAR, or TABLE SPAR. The schaalstein of Werner, and prismatic au- gite of Jameson. Colour grayish-white. Massive, and in an- gular-granular concretions. Shining pearly. Cleavage double. Fracture splintery. Trans- lucent. Harder than flu or spar, but not so hard as apatite. Brittle. Sp. gr. 3-2 to 3-5. Its constituents are, silica 50, lime 45, water 5. Klaproth. It occurs in primitive rocks, at Orawicza in the Bannat of Temeswar, where it is associated with brown garnets. TACAMAHAC. A resin, having the aro- ma of musk, and soluble in alcohoL TALC. Of this mineral, Professor Jame- son's sixth sub-species of rhomboidal mica, there are two kinds ; common talc, and indu- rated talc. 1. Common talc. Colour greenish- white. Massive, disseminated in plates, imitative, and sometimes crystallized in small six-sided tables which are druses. Splendent, pearly, semi- metallic. Cleavage single, with curved folia. Translucent. Flexible, but not elastic. Yields to the nail. Perfectly sectile. Feels very greasy. Sp. gr. 2-77 It whitens, and at length affords a small globule of enamel, before the blowpipe. Its constituents are, silica 62, magnesia 27, alumina 1.5, oxide of iron 3-5, water 0. Vauquelin. Klaproth found 2-75 of potash in 100 parts. It occurs in beds in mica-slate and clay-slate. It is found in Aberdeenshire, Banffshire, and Perth- shire. The finest specimens come from Salt z- burg, the Tyrol, and St. Gothard. It is an ingredient in rouge for the toilette, along with carmine and benzoin. This cosmetic commu- nicates a remarkable degree of softness to the skin, and is not injurious. The flesh polish is given to gypsum figures, by rubbing them with talc. 2. Indurated talc, or talc-slate. Colour greenish-gray. Massive. Fragments tabular. Translucent on the edges. Soft. Streak white. Rather sectile. Easily frangible. Not flexi- ble. Feels greasy. Sp. gr. 2-7 to 2-8. It occurs in primitive mountains, where it forms beds in clay- slate and serpentine. It is found in Perthshire, Banffshire, the Shetland Islands, and abundantly on the continent. It is em- ployed for drawing lines by carpenters, tailors, hat-makers, and glaziers. -Jameson. TALCITE. Nacrite of Jameson, and earthy talc of Werner. Colour greenish- white. It consists of scaly parts. Glimmering, pearly. Friable. Feels very greasy. Soils. It melts easily before the blowpipe. Its con- stituents are, alumina 81 -75, magnesia 0-75, lime 4, potash 0-5, water 13-5 John. This is a very rare mineral, occurring in veins, with sparry ironstone and gatena, in the mining district of Freyberg. TALLOW. Sec FAT. TAN 759 TAN TALLOW (MOUNTAIN). Specimens of this substance were lately found in a bog on the borders of Loch Fyne in Scotland. This curious mineral was first observed by some peasants on the coast of Finland in 1736; and it was afterwards found in one of the Swedish lakes. It has the colour and feel of tallow; and is tasteless. It melts at 118 F. and boils at 290. When melted it is transparent and colourless, on cooling it be- comes opaque and white, though less so than at first. It is insoluble in water, but soluble in hot alkohol, oil of turpentine, olive oil, and naphtha ; but precipitates as these liquids cool. Its sp. grav. in the natural state is 0-6078, but it is then full of air bubbles. After fusion, its density is 0-083, wMch is something above ordinary tallow. It does not combine with alkalis nor form soap. Thus it differs from every class of bodies known. From the fixed oils, in not saponifying ; from the volatile oils and bitumen, in being tasteless and destitute of smell. In volatility and com- bustibility it resembles naphtha. Edin. Phil. Journ. xi. 214. TALLOW (PINEY). A concrete inflam, mable substance, obtained by boiling in water the fruit of the Vateria Indlca, a tree common on the Malabar coast. It partakes of the nature of both wax and oil, and from its appearance may not inaptly be termed a tal- low. It is employed in the town of Manga- lore as an external application for bruises and rheumatic pains. It melts at 97^ F. ; is generally white, sometimes yellow, and is greasy to the touch with some degree of waxi- ness. Sp. gr. 0-926 at 60<>. It is not soluble in alcohol, which takes merely 2 per cent, of elain. Fixed alkalis saponify it. It forms excellentcandles, comingfreely from themould. Its ultimate constituents are, Carbon, 77-0 = 10 atoms. Hydrogen, 12-3 = 9 Oxygen, 10-7 = 1 Dr. Babington, in Journal of Science, xix. 177 TAMARINDS. The pulp consists, ac- cording to Vanquelin, of bitartrate of potash 300, gum 432, sugar 1152, jelly 576, citric acid 864, tartaric acid 144, malic acid 40, feculent matter 2880, water 3364; in 9752 parts. TANNIN. This, which is one of the immediate principles of vegetables, was first distinguished by Seguin from the gallic acid, with which it had been confounded under the name of the astringent principle. He gave it the name of tannin, from its use in the tanning of leather ; which it effects by its characteristic property, that of forming with gelatin a tough insoluble matter. It may be obtained from vegetables by macerating them in cold water; and preci- pitated from this solution, which contains likewise gallic acid and extractive matter, by hyperoxygenfaed muriate of tin. From this precipitate, immediately diffused In a large quantity of water, the oxide of tin may be separated by sulphuretted hydrogen gas, leav- ing the tannin in solution. Professor Proust has since recommended another method, the precipitation of a decoc- tion of galls by powdered caifconate of potash, washing well the greenish-gray flakes that- fall down with cold water, and drying them in a stove. The precipitate grows brown in the air, becoines brittle and shining like a resin, and yet remains soluble in hot water. The tannin in this state, he says, is very pure. Sir H. Davy, after making several experi- ments on different methods of ascertaining the quantity of tannin in astringent infusions, prefers for this purpose the common process of precipitating the tannin by gelatin ; but he remarks, that the tannin of different vegeta- bles requires different proportions of gelatin for its saturation ; and that the quantity of precipitate obtained is influenced by the degree in which the solutions are concentiated. M. Chenevix observed, that coffee berries acquired by roasting the property of precipi- tating gelatin ; and Mr. Hatchett has made a number of experiments, which show that an artificial tannin, or substance having its chief property, may be formed, by treating with nitric acid matters containing charcoal. It is remarkable that this tannin, when prepared from vegetable substances, as dry charcoal of wood, yields, on combustion, products analo- gous to those of animal matters. From his experiments it would seem, that tannin is, in reality, carbonaceous matter combined with oxygen ; and the difference in the proportion of oxygen may occasion the differences in tb.2 tannin procured from different substances, that from catechu appearing to contain most. Bouillon Lagrange asserts, that tannin by absorbing oxygen is converted into gallic acid. It is not an unfrequent practice, to admi- nister medicines containing tannin in cases of debility, and at the same time to prescribe gelatinous food as nutritious. But this is evidently improper, as the tannin, from its chemical properties, must render the gelatin indigestible. For the chief use of tannin, see the following article. According to Berzelius, tannin consists of hydrogen 4-186 -j- carbon 51-160 -j- oxygen 44-654. And the tannate of lead is com- posed of, Tannin, 100 26-923 Oxide of lead, 52 14- But there is much uncertainty concerning the definite neutrality of this compound. TANNING. The several kinds of leather are prepared from the skins of animals mace- rated for a long time with lime and water, to promote the separation of the hair and wool, and of the fat and fleshy parts, in which recourse is also had to the assistance of mechanic*! TAN 760 TAN pressure, scraping, and the like. The skin, when thus deprived of its more putrescible part, and brought considerably toward the state of mere fibre, is tanned by maceration with certain astringent substances, particularly the bark of the oak-tree. The hide consists almost wholly of gelatin, and all that is necessary is, to divest it of the hair, epidermis, and any flesh or fat adhering to it This is commonly done, after they have been soaked in water some time, and handled or trodden to cleanse them from filth, by immersing them in milk of lime. Some, instead of lime, use an acescent infusion of barley or rye-meal, or spent tan ; and others recommend water acidulated with sulphuric acid. Similar acidulous waters aie afterward employed for raising or swelling the hide, when this is necessary. The skins, thus prepared, are finally to undergo what is properly called the tanning. This is usually done by throwing into a pit, or cistern made in the ground, a quantity of ground oak-bark that has already been used, and on this the skins and fresh bark in alter- nate layers, covering the whole with half a foot of tan, and treading it well down. The tanning may be accelerated by adding a little water. As it is a long time before the hide is thoroughly tanned in this mode, at least many months, during which the bark is renewed three or four times ; M. Seguin steeps the skins in a strong infusion of tan, and assists its action by heat. Chaptal observes, however, that this requires an extensive apparatus for preparing the liquor and the skins : the leather imbibes so much water, that it remains spongy a long time, and wrinkles in drying ; and it is extremely difficult so to arrange the hides in a copper, as to keep them apart from each other, and free of the sides of the vessel. The following account of M. Seguin's practice was transmitted to England in the year 1796: To tan a skin is to take away its putrescent quality, preserving, however, a certain degree of pliability. This is effected by incorporating with the skin particles of a substance which destroys their tendency to putrefaction. The operations relating to tanning are there- fore of two kinds : the first is merely depriving the skin of those parts which would oppose its preservation, or which adhere to it but little, such as hair and flesh ; the other consists in incorporating with it a substance, which shall prevent its putrefying. The operations of the first kind are tech- nically termed, unhairing and fleshing; the operations of the second kind belong to tan- ning, properly so called. Fleshing is an operation merely mechanical : unhairing is a mechanical operation if per- formed by shaving ; or a chemical operation, if effected by dissolution or decomposition of the substance which connects the hah- with the skin. According to the ancient method, the dis- solution of this substance was effected by means of lime : the decomposition either by the vinous fermentation of barley, by the acetous fermentation of oak-bark, or by the putrid fermentation produced by piling the hides one upon another. Unhairing by means of lime would often take twelve or fifteen months ; this operation with barley, or the acetous part of tan, could not be performed in less than two months. The slowness of these operations, which the experiments of Seguin have shown may be finished in a few days, and in a more advan- tageous manner, by means of the same sub- stances, proves, that the nature of those operations was not understood by those who performed them. Those of tanning, properly so called, were as little known, as the details we arc about giving will prove, which we compare with the least improved routine now in practice. Whatever the method of unhairing was, the mode of tanning was always the same, for skins unhaired with lime, or those prepared with barley or tan. This mode of operating would take eighteen months or two years, often three years, when it was wished to tan the hides thoroughly. Among the substances for tanning gall- nut, sumach, and the bark of oak, to which may be added catechu, appear the most proper, at least, in the present state of our knowledge. In the middle departments of France, oak- bark is preferred, because it is the cheapest and most abundant substance. To use it, it is first ground to powder ; then, according to the old mode, it is put into large holes dug in the ground, which are filled by alternate layers of ground bark and unhaired hides. As the principle which effects the tanning cannot act in the interior of the skin, unless carried in by some liquid in which it is first dissolved, tanning is not produced by the im- mediate action of the powdered bark upon the skin, but only by the action of the dissolution of the tanning principle originally contained in the bark. The tan therefore has the tanning property only when wetted so much as not to absorb all the water thrown on it. But as tanners put in their vats only a small portion of water compared to what would be necessary to deprive the bark of all the tanning principle which it contains, the bark put into the vats preserves, when taken out, a portion of its tanning principle. This waste is not the only disadvantage of the old modes of proceeding; they are, be- sides, liable never to produce in the skins a complete saturation with the tanning principle. For, as the property of attraction is common to all bodies, according to the different degree of saturation, the water containing in solution a TAN 761 TAN certain quantity of the tanning principle, will not part, to a fixed weight of skins, with as much as the same quantity of water will, in which a greater quantity of the principle is dissolved. As the water which, in the old manner of proceeding, is in the vats, can contain but a small portion of the tanning principle, owing to the nature of the operation, it can give but a small portion of it to the skin, and even this it parts with by slow degrees. Hence, the slowness in the tanning of skins, according to the old method, which required two whole years, and sometimes three, before a skin was well tanned to the centre. Hence also, the imperfection of skins tanned by that method ; an imperfection resulting from the non-satura- tion of the tanning principle, even when it had penetrated the centre. The important desideratum was, therefore, to get together, within a small compass, the tanning principle, to increase its action, and produce in the hide a complete saturation in a much shorter time than that necessary for the incomplete tanning produced in vats. But, first of all, it was necessary to analyze the skin, analyze the leather, and analyze the oak-bark. The principles of these three substances were to be insulated, and their action upon one another determined, the influence of their combination upon that action known, and the circumstances most productive of its greatest action found out. Seguin, by following this method, has de- termined : 1. That the skin deprived of flesh and hair is a substance which can easily, by a proper process, be entirely converted into an animal jelly (glue). 2. That a solution of this last mentioned substance, mixed with a solution of tan, forms immediately an imputrescible and indissoluble compound. 3. That the solution of tan is composed of two very distinct substances; one of which precipitates the solution of glue, and which is the true tanning substance ; the other, which precipitates sulphate of iron, without precipi- tating the solution of glue, and which produces only the necessary disoxygenation of the skin, and of the substance which connects the hair to the skin. 4. That the operation of tanning is not a simple combination of the skin with the prin- ciple which precipitates the glue, but a com- bination of that principle with the skin disoxygenized by the substance, which in the solution of tan is found to precipitate the sul- phate of iron ; so that every substance proper for tanning should possess the properties of precipitating the solution of glue, and of pre- cipitating the sulphate of iron. 5. That the operation of tanning consists in swelling the skins by means of an acidulous principle ; to disoxygenize, by means of the principle which in the solution of bark pre- cipitates the solution of sulphate of iron, that substance which connects the hair to the skin, and thus produce an easy unhairing ; to disoxygenize the skin by means of the same principle, and to bring it by this disoxygena- tion to the middle state between glue and skin ; and then to combine with it, after this disoxygenation, and while it is in this middle state, that particular substance in oak-bark, as well as in many other vegetables, which is found to precipitate the solution of glue, and which is not, as has been hitherto conceived, an astringent substance. Agreeably to these discoveries, there only remains, in order to tan speedily and com- pletely, to condense the tanning principle so as to accelerate its action. Seguin, to effect this, follows a very simple process. He pours water upon the powdered tan, contained in an apparatus nearly similar to that made use of in saltpetre works. This water, by going through the tan, takes from it a portion of its tanning principle, and by successive filtrations dissolves every time an additional quantity of it, till at last the bark rather tends to deprive it of some than to give up more. Seguin succeeds in bringing these solutions to such a degree of strength, that, he says, he can, by taking proper measure, tan calf-skin in 24 hours, and the strongest ox-hides in seven or eight days. These solutions containing a great quantity of the tanning principle, impart to the skin as much of it as it can absorb, so that it can then easily attain a complete saturation of the principle, and produce leather of a qua- lity much superior to that of most countries famous for their leather. On the above I have only to remark, that every new art or considerable improvement must unavoidably be attended with many dif- ficulties in the establishment of a manufactory in the large way. From private inquiry I find, that this also has its difficulties, which have hitherto prevented its being carried into full effect in this country. Of what nature these may be I am not decidedly informed, and mention them in this place only to pre- vent manufacturers from engaging in an undertaking of this kind, without cautious inquiry. M. Desmond has recommended, to saturate water with tannin, by affusion on successive portions of oak-bark, or whatever may be used; and when the bark will give out no more tannin, to extract what gallic acid still remains in it, by pouring on fresh water. To the latter, or acidulous liquor, he adds one- thousandth part by measure of sulphuric acid ; and in this steeps the hide, till the hair will come off easily by scraping. When raising is necessary, he steeps the hide ten or twelve hours in water acidulated with a five-hundredth part by measure of sulphuric acid; after which they are to be washed repeatedly, and scraped TAR 702 TEA with (ho round knife. Lastly, the hides are to be steeped some hours in a weak solution of tannin, then a few days in a stronger, and this must be renewed as the tannin is exhausted, till the leather is fully tanned. For the softer skins, as calves, goats, &c., he does not use the acid mixture, but milk of lime. Of substances used for tanning Sir H. Davy observes, that 1 Ib. of catechu is nearly equal to 2\ of galls, 3 of sumach, 7% of the bark of the Leicester willow, 8 of oak-bark, 11 of the bark of the Spanish chestnut, 18 of elm-bark, and 21 of common willow-bark, with respect to the tannin contained in them. He observes too, that leather slowly tanned in weak infu- sions of barks appears to be better in quality, being both softer and stronger than when tanned by strong infusions; and he ascribes this to the extractive matter they imbibe. This principle, therefore, affects the quality of the material employed in tanning ; and galls, which contain a great deal of tannin, make a hard leather, and liable to crack, from their deficiency of extractive matter. Ann. de Chim. ct de Phys.Philos. Trans Fhilos. Mag. ChaptaVs Chem. TANTALUM ORE. See ORE OP TAN. TALUM. TANTALUM. The metal already treated of under the name COLUMBIUM. TAPIOCA. A species of starch, prepared from the jatropha manehat. See CASSAVA. TARRAS, OR TERRAS. A volcanic earth used as a cement. It does not differ much in its principles from puzzolana ; but it is much more compact, hard, porous, and spongy. It is generally of a whitish-yellow colour, and contains more heterogeneous parti, cles, as spar, quartz, schorl, &c. and something more of a calcareous earth. It effervesces with acids, is magnetic, and fusible per se. When pulverized, it serves as a cement, like puz- zolana. It is found in Germany and Sweden. See LIME, CEMENT, and PUZZOLANA. TARTAR is deposited on the sides of casks during the fermentation of wine ; it forms a lining more or less thick, which is scraped off. This is called crude tartar, and is sold in Languedoc from 10 to 15 livres the quintal. All vines do not afford the same quantity of tartar. Neumann remarked, that the Hun- garian wines left only a thin stratum ; that the wines of France afforded more ; and that the Rhenish wines afforded the purest and the greatest quantity. Tartar is distinguished from its colour into red and white: the first is afforded by red wine. Tartar is purified from an abundant extrac- tive principle, by processes which are executed at Montpdlier and at Venice. The following is the process used at Mont- pellier : The tartar is dissolved in water, and suffered to crystallize by cooling. The crystals are then boiled in another vessel, with the addition of five or six pounds of the white argillaceous earth of Murviel to each quintal of the salt. After this boiling with the earth, a very white salt is obtained by evaporation, which is known by the name of cream of tartar, or the acidulous tartrate of potash. M. Desmaretz has informed us, that the process used at Venice consists, 1. In drying the tartar in iron boilers. 2. Pounding it, and dissolving it in hot water, which, by cooling, affords purer crystals. 3. Redissolving these crystals in water, and clarifying the solution by whites of eggs and ashes. The process of Montpellier is preferable to that of Venice. The addition of the ashes introduces a foreign salt, which alters the pu- rity of the product. See ACID (TARTARIC). TARTAR (CHALYBEATED). This is prepared by boiling three parts of the su- pertartrate of potash and two of iron filings in forty-six parts of water, till the tartar appears to be dissolved. The liquor is then filtered, and crystals are deposited on cooling, more of which are obtained by continuing the eva- poration. TARTAR (CREAM OF). The popular name of the purified supertartrate of potash. TARTAR (CRUDE). The supertartrate of potash in its natural state, before it has been purified. TARTAR (EMETIC). The tartrate of potash and antimony. See ANTIMONY. TARTAR OF THE TEETH. The popular name for the concretion that so fre- quently incrusts the teeth, and which consists apparently of phosphate of lime. TARTAR (REGENERATED). Acetate of potash. TARTAR (SALT OF). The subcar- bonate of potash. TARTAR (SECRET FOLIATED EARTH OF ). Acetate of potash. TARTAR (SOLUBLE). Neutral tar- trate of potash. TARTAR (VITRIOLATED). Sul- phate of potash. TARTARINE. The name given by Kirwan to the vegetable alkali, or potash. TARTAROUS ACID. See ACID (TARTARIC). TARTRATE. A neutral compound of the tartaric acid with the base. TEA. The following interesting results of experiments on tea by Mr. Brande have been published by him in his Journal, xii. 206. TEE 763 TEL One hundred parts of Tea. Soluble in water. Soluble in Alcohol. Precipit. with Jelly. Inert residue. Green Hyson, 14*. per Ib. 41 44 31 56 Ditto, - 12*. 34 43 29 57 Ditto, - 10*. 36 43 26 57 Ditto, 8*. 36 42 25 58 Ditto, - 7*. 31 41 24 59 Black Souchong, 12*. 35 36 28 64 Ditto, - 10*. 34 37 28 63 Ditto, - 8*. 37 35 28 63 Ditto, - 7*. 36 35 24 64 Ditto, - 6*. 35 31 23 65 TEARS. That peculiar fluid which is employed in lubricating the eye, and which is emitted in considerable quantities when we express grief by weeping, is known by the name of tears. For an accurate analysis of this fluid we are indebted to Messrs. Fourcroy and Vauquelin. The liquid called tears is transparent and colourless like water ; it has scarcely any smell, but its taste is always perceptibly salt. Its specific gravity is somewhat greater than that of distilled water. It gives to paper stained with the juice of the petals of mallows or violets a permanently green colour, and therefore contains a fixed alkali. It unites with water, whether cold or hot, in all pro- portions. Alkalis unite with it readily, and render it more fluid. The mineral acids pro- duce no apparent change upon it. Exposed to the air, this liquid gradually evaporates and becomes thicker. When nearly reduced to a state of dryness, a number of cubic crystals form in the midst of a kind of mu- cilage. These crystals possess the properties of muriate of soda ; but they tinge vegetable blues green, and therefore contain an excess of soda. The mucilaginous matter acquires a yellowish colour as it dries. Tears are composed of the following in- gredients : 1. Water, 2. Mucus, 3. Muriate of soda, 4. Soda, 5. Phosphate of lime, 6. Phosphate of soda. The saline parts amount only to about 0-01 of the whole, or probably not so much. TEETH. The basis of the substance that forms the teeth, like that of other bones, (see BONE), appears to be phosphate of lime. The enamel, however, according to Mr. Hatchett, differs from other bony substances ia being destitute of cartilage: for raspings of enamel, when macerated in diluted acids, he found were wholly dissolved ; while rasp- ings of bone, treated in the same manner, always left a cartilaginous substance un- touched. Sec BONE. TELESIA. Sapphire. TELLURIUM. Mueller first suspected the existence of a new metal in the aurum paradoxicum or problematicum, which has the appearance of an ore of gold, though very little can be extracted from it. Klaproth afterward established its existence, not only is this but in some other Transylvanian ores, and named it tellurium. Pure tellurium is of a tin-white colour, verging to lead-gray, with a high metallic lustre ; of a foliated fracture ; and very brittle, so as to be easily pulverized. Its sp. gr. is 6.115. It melts before ignition, requiring a little higher heat than lead, and less than antimony ; and, according to Gme- lin, is as volatile as arsenic. When cooled without agitation, its surface has a crystal- lized appearance. Before the blowpipe on charcoal it burns with a vivid blue light, greenish on the edges; and is dissipated in grayish-white vapours, of a pungent smell, which condense into a white oxide. This oxide heated on charcoal is reduced with a kind of explosion, and soon again volatilized. Heated in a glass retort it fuses into a straw- coloured striated mass. It appears to contain about 16 per cent, of oxygen. Tellurium is oxidized and dissolved by the principal acids. To sulphuric acid it gives a deep purple colour. Water separates it in black flocculi, and heat throws it down in a white precipitate. With nitric acid it forms a colourless so- lution, which remains so when diluted, and affords slender dendritic crystals by evapora- tion. The muriatic acid, with a small portion of nitric, forms a transparent solution, from which water throws down a white submuriate. This may be redissolved almost wholly by repeated affusions of water. Alcohol likewise pre- cipitates it. Sulphuric acid, diluted with two or three parts of water, to which a little nitric acid has been added, dissolves a large portion of the metal, and the solution is not decomposed by water. The alkalis throw down from its solutions TEM 764 TEM a white precipitate, which is soluble in all the acids, and by an excess of the alkalis or their carbonates. They are not precipitated by prussiate of potash. Tincture of galls gives a yellow flocculent precipitate with them. Tellurium is precipitated from them in a me- tallic state by zinc, iron, tin, and antimony. Tellurium fused with an equal weight of sulphur, in a gentle heat, forms a lead-co- loured striated sulphuret. Alkaline sulphurets precipitate it from its solutions of a brown or black colour. In this precipitate either the metal or its oxide is combined with sulphur. Each of these sulphurets burns with a pale blue flame, and white smoke. Heated in a retort, part of the sulphur is sublimed, carry- ing up a little of the metal with it It does not easily amalgamate with quicksilver. TELLURETTED HYDROGEN. Tel- lurium and hydrogen combine to form a gas, called telluretted hydrogen. To make this compound, hydrate of potash and oxide of tellurium are ignited with charcoal, and the mixture acted on by dilute sulphuric acid, in a retort connected with a mercurial pneumatic apparatus. An elastic fluid is generated, consisting of hydrogen holding tellurium in solution. It is possessed of very singular properties. It is soluble in water, and forms a claret-coloured solution. It combines with the alkalis. It burns with a bluish flame, depositing oxide of tellurium. Its smell is very strong and peculiar, not unlike that of sulphuretted hydrogen. This elastic fluid was discovered by Sir H. Davy in 1809. When tellurium is made the electrical ne- gative surface in water in the voltaic circuit, a brown powder is formed, which appears to be a solid combination of hydrogen and tel- lurium. It was first observed by Mr. Ritter in 1808. The composition of the gas and the solid hydruret has not been ascertained. The prime equivalent of tellurium, according to Sir H. Davy, is 4-93, reduced to the oxy- gen radix. Berzelius makes the oxide of tellurium a compound of metal 100 + oxygen 24.8. If we call the oxygen 25, then the atom or prime would be 4. In this case tel- luretted hydrogen, if analogous in its con- stitution to sulphuretted hydrogen, would have a sp. gr. of 2-2916, (not 2-3074, as Dr. Thomson deduces it from the same data). TEMPERATURE. A definite degree of sensible heat, as measured by the thermo- meter. Thus we say a high temperature, ami a low temperature, to denote a manifest intensity of heat or cold ; the temperature of boiling water, or 212 Fahr. ; and a range of temperature, to designate the intermediate points of heat between two distant terms of thermometric indication. According to M. Biot, temperatures are the different energies of caloric, in different circumstances. The general doctrines of caloric have been already fully treated of under the articles Calorie, Combustion, Congelation, Cttnfate, and Pyrometer. The changes induced on matter, at different temperatures, relate either to its magnitude, form, or composition. The first two of these effects are considered under Expansion, Con- creting Temperatures, and Pyrometer; the third under Combustion, and the Individual Chemical Bodies. I shall here introduce some facts concerning the temperature of living bodies, and that of our northern climates, as modified by the constitution of water. The power which man possesses of resisting the impression of external cold is well known, and fully exemplified in high latitudes. That of sustaining high heats has been made the subject of experiment. On the Continent, the girls who are sent into ovens often endure for a short period a heat of 300 F. and up- wards. If the skin be covered with varnish, which obstructs the perspiration, such heats, however, become intolerable. Dr. Fordyce staid for a considerable time, and without great inconvenience, in a room heated by stoves to 260 of Fahrenheit's scale. The lock of the door, his watch and keys, lying on the table, could not be touched without burning his hand. An egg became hard; and though his pulse beat 139 times per minute, yet a thermometer held in his mouth was only 2 or 3 hotter than ordinary. He perspired most profusely. Phil. Trans, vol. 64, and 65. It has been shown under Caloric, that fresh water possesses a maximum density about 39 F. When its temperature deviates from this point, either upwards or downwards, its density diminishes, or its volume enlarges. Hence, when the intensely cold air from the circum-polar regions presses southwards, after the autumnal equinox, it progressively ab- stracts the heat from the great natural basins of water or lakes, till the temperature of the whole aqueous mass sinks to 39. At this term the refrigerating influence of the atmo- sphere incumbent on the water becomes nearly null. For, as the superficial stratum, by farther cooling, becomes specifically lighter, it remains on the surface, and soon becomes a cake of ice, which being an imperfect con- ductor of heat, screens the subjacent liquid water from the cold air. Had water resembled mercury, oils, and other liquids, in continuing to contract in volume, by cooling, till its con- gelation commenced, then the incumbent cold air would have robbed the mass of water in a lake of its caloric of fluidity, by unceasing precipitation of the cold particles to the bottom, till the whole sunk to 32. Then the water at the bottom, as well as that above, would have begun to solidify, and in the course of a severe winter in these latitudes, a deep lake would have become throughout a body of ice, never again to be liquefied. We can easily see, that such frozen masses would have acted THE 765 THE us centres of baleful refrigeration to the sur- rounding country ; and that under such a disposition of things, Great Britain must have been another Lapland. Nothing illustrates more strikingly the beneficent economy of Providence, than this peculiarity in the con- stitution of water, or anomaly, as it has been rather preposterously termed. What seems void of law to unenlightened man, is often, as in the present case, found to be the finest symmetry, and truest order. TENACITY. See COHESION. TENSION OF VAPOURS. See VA- POUR. TENNANTITE. Colour, from lead-gray to iron-black. Massive, but usually crystal- lized, in rhomboidal dodecahedrons, cubes, or octohedrons. Splendent, and tin-white; occasionally dull. Cleavage dodecahedral. Streak reddish-gray. Rather harder than gray copper. Brittle. Sp. gr. 4-375. It yields a blue flame, followed by arsenical vapours ; and leaves a magnetical scoria. Its constituents are, copper 45-32, sulphur 28-74, arsenic 11-84, iron 9-26, silica 5. Richard Phillips. It occurs in Cornwall in copper veins that intersect granite, and clay-slate, associated with common copper pyrites. It is a variety of gray copper. TERRA PONDEROSA. See HEAVY SPAR and BARYTES. TERRA JAPONICA. Catechu. TERRA LEMN1A. A red bolar earth formerly esteemed in medicine. See LEM- NIAK EARTH. TERRA SIENNA. A brown bole, or ochre, with an orange cast, brought from Sienna in Italy, and used in painting, both raw and burnt. When burnt, it becomes of a darker brown. It resists the fire a long time without fusing. It adheres to the tongue very forcibly. TERRE VERTE. This is used as a pigment, and contains iron in some unknown state, mixed with clay, and sometimes with chalk and pyrites. TEST. In chemistry, any reagent, which, added to a substance, teaches us to distinguish its chemical nature or composition. THALLITE. Epidote or pistacite. THERMO-ELECTRO-MAGNETISM. M. Seebeck discovered that an electrical cur- rent can be established in a circuit formed exclusively of solid conductors, by disturbing merely the equilibrium of temperature. These constitute the subject called by the above de- nomination. MM. Fourier and Oersted en- deavoured to ascertain whether the thermo- electric effects may be increased by the alter- nate repetition of bars of different materials. Their first apparatus was composed of three bars of bismuth and three of antimony, sol- dered alternately together, so as to form a hexagon, constituting a thermo-electric circuit, which includes three elements, or three pairs. The length of the bars was about 4-7 inches ; their breadth 0-6 of an inch, and their thickness 0-1 (> of an inch. This circuit was put upon two supports, and in a horizontal position, observing to give to one of the sides of the hexagon the direction of the magnetic needle. A compass needle was then placed below this side, and as near it as possible. On heating one of the solderings with the flame of a lamp, they produced a very sensible effect on the needle. On heating two solderings not con- tiguous, the deviation became considerably greater ; and on heating the three alternate ones a still greater effect was produced. He like- wise made use of an inverse process, that is to say, they reduced to 32 F. by melting ice, the temperature of one or more solderings of the circuit. In this case the solderings not cooled must be regarded as heated in reference to the others. By combining the action of the ice with that of the flame, viz. by heating three solderings, and cooling the other three, the deviation of the needle amounted to 60. Ann. de Chim. et Phys. xxii. 375, or Journal of Science, xvi. 126. THERMOMETER. An instrument for measuring heat, founded on the principle, that the expansions of matter are proportional to the augmentations of temperature. With regard to aeriform bodies, this principle is probably well founded ; and, hence, our com- mon thermometers may be rendered just, by reducing their indications to those of an air thermometer. Solids, and still more liquids, expand unequally, by equal increments of heat, or intervals of temperature. With regard to water, alcohol, and oils, this inequality is so considerable as to occasion their rejection, for purposes of exact thermometry. But we have shown that mercury approaches more to solids than ordinary liquids, in its rate of expansion, and hence, as well as from its remaining liquid through a long range of temperature, it is justly preferred to the above substances for thermometric purposes. A common thermometer, therefore, is merely a vessel in which very minute expansions of mercury may be rendered perceptible ; and, by certain rules of graduation, be compared with expansions made on the same liquid, by other observers. The first condition is fulfilled, by connecting a narrow glass tube with a bulb of considerable capacity, filled with quicksilver. As this fluid metal expands l-63d by being heated in glass vessels, from the melting point of ice to the boiling point of water, if 10 inches of the tube have a capacity equal to l-63d of that of the bulb, it is evident that, should the liquid stand at the beginning of the tube at 32, it will rise up and occupy 10 inches of it at 212. Hence, if the tube be uniform in its calibre, and the above space be divided into equal parts, by an attached scale, then we shall have a centigrade or Fahrenheit's thermometer, according as the divisions are THE 766 THE 100 or 180 In number. 8uch are the general principles of thermometric construction. But to make an exact instrument, more minute investigation is required. The tubes drawn at glass-houses for making thermometers are all more or less irregular in the bore, and for the most part conical. Hence, if equal apparent expansions of the included mercury be taken to represent equal thermometric intervals, these equal expansions will occupy unequal spaces in an irregular tube. The attached scale should therefore correspond exactly to these tubular inequalities ; or if the scale be uniform in its divisions, we must be certain that the tube is absolutely uniform in its calibre. I may join the authority of Mr. Troughton's opinion to my own, for affirming, that a tube of a truly equable bore is seldom or never to be met with. Hence we should never construct our thermometers on that supposition. The first step in the formation of this instru- ment, therefore, is to graduate the tube into spaces of equal capacity. A small caoutchouc bag, with a stop-cock and nozzle capable of admitting the end of the glass tube, when it is wrapped round with a few folds of tissue paper, must be provided ; as also pure mer- cury, and a sensible balance. Having expelled a little air from the bag, we dip the end of the attached glass tube into the mercury, and by the elastic expansion of the caoutchouc, we cause a small portion of the liquid to rise into the bore. We then shut the stop-cock, place the tube in a horizontal direction, and remove it from the bag. The column of mercury should not exceed half an inch in length. By gently inclining the tube, and tapping it with our finger, we bring the mercury to about a couple of inches from the end where we mean to make the bulb, and, with a file or diamond, mark there the initial line of the scale. The slip of ivory, brass, or paper, destined to receive the graduations, being laid on a table, we apply the tube to it, so that the bottom of the column of mercury coincides with its lower edge. With a fine point, we then mark on the scale the other extremity of the mer- curial column. Inclining the tube gently, and tapping it, we cause the liquid to flow along till its lower end is placed where the upper previously stood. We apply the tube to the scale, taking care to make its initial line correspond to the edge as before. A new point for measuring equal capacity is now obtained. We thus proceed till the requisite length be graduated ; and we then weigh the mercury with minute precision. The bulb is next formed at the enameller's blowpipe in the usual way. One of a cy- lindrical or conical shape ig preferable to a sphere, both for strength and sensibility. We now ascertain, and note down its weight. A tubular coil ot paper is to be tied to the mouth of the tube, rising in a funnel-form an inch or two above it. Into thfe we pour recently boiled mercury ; and applying the gentle heat of a lamp to the bulb, we expel a portion of the ah*. On allowing the bulb to cool, a portion of the mercury will descend into it, corresponding to the quantity of air pre- viously expelled. The bulb is now to be heated over the lamp till the included mercury boil briskly for some time. On removing it, the quicksilver will descend from the paper funnel, and completely fill the bulb and stem. Should any vesicle of air appear, the process of heating or boiling must be repeated, with the precaution of keeping a column of super- incumbent mercury in the paper funnel. When the temperature of the bulb has sunk to nearly that of boiling water, it may be immersed in melting ice. The funnel and its mercury are then to be removed, and the bulb is to be plunged into boiling water. About l-63d of the included mercury will now be expelled. On cooling the instrument again in melting ice, the zero point of the centigrade scale, corresponding to 32 of Fahrenheit, will be indicated by the top of the mercurial column. This point must be noted with a scratch on the glass, or else by a mark on the prepared scale. We then weigh the whole. We have now sufficient data for completing the graduation of the instrument from one fixed point ; and in hot climates, and other situations, where ice, for example, cannot be conveniently procured, this facility of forming an exact thermometer is important. We know the weight of the whole included mercury, and that of each gradus of the stem. And as from 32 to 212 F. or from to 100 cent, corresponds to a mercurial expansion in glass of l-63d, we can easily compute how many of our graduating spaces are contained in the range of temperature, between freezing and boiling water. Thus, supposing the mercurial contents to be 378 grains, l-63d of that quantity, or 6 grains, correspond to 180 of Fahrenheit's degrees. Now, if the initial measuring column were 0-6 of a grain, then 10 of these spaces would comprehend the range between freezing and boiling water. Hence, if we know the boiling point, we can set off the freezing point ; or, from the tern- perature of the living body, 98 F., we can set off both the freezing and boiling points of water. In the present case, we must divide each space on our prepared scale into 18 equal parts, which would constitute degrees of Fahrenheit; or into 10 equal parts, which would constitute centigrade degrees ; or into 8, which would form Reaumur's degrees. I have graduated thermometers in this way, and have found them to be very correct. When we have ice and boiling water at our command, however, we may dispense with the weighing processes. By plunging the instrument into melting ice, and then into boiling water, we find how many of our initial spaces on the THE 767 THE stem correspond to that interval of temperature, and we subdivide them accordingly. If the tube be very unequable, we must accommo- date even our subdivisions to its irregularities, for which purpose the eye is a sufficient guide. Thermometers are used for two different purposes, each of which requires peculiar adaptation. Those employed in meteorology, or for indicating atmospherical temperature, are wholly plunged in the fluid, and hence the stem as well as bulb are equally affected by the calorific energy. But when the chemist wishes to ascertain the temperature of corrosive liquids, or bland liquids highly heated, he can immerse merely the bulb, and the naked part of the stem under the scale. The portion of the tube corresponding to the scale is not influenced by the heat, as in the former case ; and hence, l-63d part of the mercury, which at 32" F. was acted on, has at 212 escaped from its influence. (MM, Dulong and Petit make it l-G4-8th between 32 and 212* ; see CALORIC). Hence I conceive, that a me- teorological and a chemical thermometer ought to be graduated under the peculiar conditions in which they are afterwards to be used. The former should have its stem sur- rounded with the steam of boiling water, while its bulb is immersed an inch or two beneath the surface of that liquid, the barometer having at the time an altitude of 30 inches. For ascertaining the boiling point on a thermometer stem, I adapt to the mouth of a tea-kettle a cylinder of tin-plate, the top of which contains a perforated cork. Through this the glass tube can be slid to any convenient point ; while the tin cylinder may also be raised or lowered, till the bulb rest an inch beneath the water. The nozzle of the kettle is shut with a cork ; and at the top of the cylinder, a side-hole for escape of the steam is left. If the barometer differs from 30 by one inch, then the boiling point of water will differ by 1-92 F. Or 1 F. by Mr. Wollaston, corresponds to a difference of 0-589 of barometric pressure. When the barometer, for example, stands at 29 inches, water boils at 210-08 F. ; and when it stands at 3 1 inches, the boiling temperature is 213-92. Particular attention must be paid to this source of variation. A thermometer for chemical experiment should have its boiling point determined, by immersion only of the bulb and the naked portion of its stem below the scale, in boiling water. It is surely needless to say, that the water ought to be pure, since the presence of saline matter affects its boiling temperature ; and it ought to be contained in a metallic vessel. Before sealing up the end of the tube, we should draw it into a capillary point, and heat the bulb till the mercury occupy the whole of the stem. A touch of the blowpipe flame on the capillary glass will instantly close tt, and exclude the air from re-entering when the bulb becomes cooL If this has been skilfully executed, the column of mercury will move rapidly from one end of the tube to the other, when it is inverted with a jerk. An ivory scale is the handsomest, but the most ex- pensive. Those used in Paris consist of a narrow slip of paper, enclosed in a glass tube, which is attached in a parallel direction to the thermometer stem. It fs soldered to it above, by the lamp, and hooked to it below, by a ring of glass. Such instruments are very convenient for corrosive liquids; and I find them not difficult to construct. In treating of the measure of temperature under CALORIC, I have endeavoured to show, that were the whole body of the thermometer, stem and bulb, immersed in boiling mercury, it would indicate 35 more than it does on the supposition of the bulb alone being subjected to the calorific influence, as takes place in common experiments. But MM. Dulong and Petit state, that it ought to indicate 080 in the former case, while Mr. Crichton shows that it actually indicates 656 in the latter, giving a difference of only 24 instead of 35. This discordance between fact and theory is only apparent; for we must recollect that mercury being an excellent conductor of heat, will communicate a portion of that expansive energy from the immersed bulb, to the mercury in the stem, which will be retained, in consequence of glass being a very imperfect conductor of heat. Hence we may infer, that but for this communication of heat to the stem, a thermometer, whose bulb alone is plunged in boiling mercury, would stand at 645 F., or 17 below the true boiling tem- perature by an air thermometer, according to MM. Dulong and Petit. If we take the mean apparent expansion of mercury, in glass, for 180, between 32<>and 662, as given by these chemists at l-64th ; then the above reduction would become 34-4 instead of 35, an incon- siderable difference. In consequence of this double compensation, a good mercurial thermometer, as constructed by Crichton, becomes an almost exact mea- sure of temperature, or of the relative apparent energies of caloric. At the end of the Dictionary a table of reduction is given for the three thermometric scales at present used in Europe ; that of Reaumur, Celsius or the centigrade, and Fahrenheit. The process of reduction is however a very simple case of arithmetic. To convert the centigrade interval into the Fah- renheit, we multiply by 1-8 or by 6 and 0-3, marking off the last figure of the product as a decimal. Thus an interval of 17 centigrade = 17 X C X 0-3=one of 30-6 Fahrenheit. But as the former scale marks the melting of ice 0, and the latter 32, we must add 32 THE 768 TIN to 30-6 to have the Fahrenheit number = 62-6. Another form of the same rule of conversion is, from double the centigrade interval subtract one-fifth, the remainder is the Fahrenheit interval. Thus, from the double of 17 =34, subtract y 3-4, the remainder 30-6 is the corresponding interval on Fahrenheit's scale. To convert the Fahrenheit intervals into the centigrade, divide by 6 and by 0-3, and mark 95 off the decimal point thus : 95 F. =g TTo 52-77 C. When we wish to reduce a Fahrenheit number to a centigrade, we must begin by deducting the 32 which the former is in advance over the latter, at the melting of ice, or zero of the French scale. Thus to convert 95 F. to the centigrade scale; 95 32 = All versed in arithmetical reduction know how advantageous it is to confine it if possible to one rule, and not to blend two or more. Hence the ordinary rule of multiplying by 9, and dividing by 5, to bring the Fahrenheit to the centigrade intervals, seems less convenient than the preceding. With regard to the Reaumur scale, however, which is now of rare occurrence, we may employ the usual proportion of 9 to 4, or to the double add one-fourth : F. =9-4ths R. and R. =4-9ths F. These are the relations of the intervals. We must, however, attend to the initial 32 of Fahrenheit. " 6x0-3 F = (Ox CxO-3)+ 32 Rn _4(F-32) Ro_ - _ - F = R 32 0-8 Ro - 0-8 X 0. In the 15th volume of the Phil. Magazine, Mr. Crichton of Glasgow has described a self- registering thermometer of his invention, con- sisting of two oblong slips of steel and zinc, firmly fixed together by their faces ; so that the greater expansion or contraction of the zinc, over those of the steel, by the same variations of temperature causes a flexure of the compound bar. As this is secured to a board at one end, the whole flexure is exercised at. the other, on the short arm of a lever index, the free extremity of which moves along a graduated arc. The instrument is originally adjusted on a good mercurial thermometer ; and the movements of the arm are registered by two fine wires, which are pushed before it, and left at the maximum deviation to' the right or left of the last observed position or temperature. The principle is obviously that of Arnold's compensation balance for chro- nometers. An exquisite instrument on the same prin- ciple has been invented by M. Breguet, member of the Academy of Sciences, and Board of Longitude of France. It consists of a narrow metallic slip, about yi^ of an inch thick, composed of silver and platina, soldered together; and it is coiled in a cylindrical form. The top of this spiral tube is suspended by a brass arm, and the bottom carries, in a horizontal position, a very delicate golden needle, which traverses as an index on a gra- duated circular plate. A steel stud rises in the centre of the tube, to prevent its oscillations from the central position. If the silver be on the outside of the spiral, then the influence of increased temperature will increase the curvature, and move the appended needle in the direction of the coil ; while the action of cold will relax the coil, and move the needle in the opposite direction. M. Breguet was so good as to present me with two instruments ; both of which are perfect thermometers, but one is the most sensible which I ever saw. For some details concerning it. see CALORIC. Dr. Wollaston showed me in 1809 a slip of copper coated with platinum, which exhibited, by its curvature over flame or the vapour of water, the expanding influence of heat, in a striking manner. For other facts concerning the measurement of heat, see CALORIC. THOMSONITE. A mineral of the zeolite family, found in the neighbourhood of Kil- patrick near Dumbarton. The primary form of its crystals is a right rectangular prism. THORINA. A supposed new earth, described as such in 1816 by M. Berzelius. He has since found it to be merely a sub- phosphate of yttria. THULITE. A hard peach-blossom co- loured mineral found at Sonland, iu Telle- mark in Norway. THUMERSTONE. Axinite. TILE ORE. A sub-species of octohedral red copper ore. TIN is a metal of a yellowish-white colour, considerably harder than lead, scarcely at all sonorous, very malleable, though not very tenacious. Under the hammer it is extended into leaves, called tin-foil, which are about one-thousandth of an inch thick, and might easily be beaten to less than half that thick- ness, if the purposes of trade required it. The process for making tin-foil consists simply in hammering out a number of plates of this metal, laid together upon a smooth block or plate of iron. The smallest sheets are the thinnest. Its specific gravity is 7-29. It melts at about the 442 of Fahrenheit's ther- mometer ; and by a continuance of the heat it is slowly converted into a white powder by oxidation. Like lead, it is brittle when heated TIN 769 TIN almost to fusion, and exhibits a grained or fibrous texture, if broken by the blow of a hammer ; it may also be granulated by agita- tion at the time of its transition from the fluid to the solid state. The oxide of tin resists fusion more strongly than that of any other metal; from which property it is useful to form an opaque white enamel when mixed with pure glass in fusion. The brightness of its surface, when scraped, soon goes off by exposure to the air ; but it is not subject to rust or corrosion by exposure to the weather. To obtain pure tin, the metal should be boiled in nitric acid, and the oxide which falls down reduced by heat in contact with charcoal, in a covered crucible. There are two definite combinations of tin and oxygen. The first or protoxide is gray ; the second or peroxide is white. The first is formed by heating tin in the air, or by dis- solving tin in muriatic acid, and adding water of potash to the solution whilst recent, and before it has been exposed to air. The pre- cipitate, after being heated to whiteness to expel the water of the hydrate, is the pure protoxide. It is convertible into the per- oxide by being boiled with dilute nitric acid, dried and ignited. According to Sir H. Davy, the protoxide contains 13.5 per cent, of oxygen. Supposing it to consist of a prime equivalent of each constituent, that of tin would be 7-333. From the analyses of Berzelius and Gay Lussac, the peroxide is composed of 100 metal -\- 27-2 oxygen ; and if we regard it as containing two primes of the latter principle to 1 of metal, the prime of this will be 7-353. The mean maybe taken at 7-35. There are also two chlorides of tin. When tin is burned in chlorine, a very volatile clear liquor is formed, a non-conductor of electricity, and which, when mixed with a little water, becomes a solid crystalline substance, a true muriate of tin, containing the peroxide of the metal. This, which has been called the liquor of Libavius, may be also procured, by heating together tin-filings and corrosive sublimate, or an amalgam of tin and corrosive sublimate. It consists, according to the analysis of Dr. John Davy, of 2 primes of chlorine m 9 + 1 of tin = 7-35. The other compound of tin and chlorine is a gray semitransparent crys- talline solid. It may be procured by heating together an amalgam of tin and calomel. It dissolves in water, and forms a solution, which rapidly absorbs oxygen from the air, with deposition of peroxide of tin. It consists of, Chlorine, 4-5 Tin, 7-35 There are two sulphurets of tin. One may be made by fusing tin and sulphur together. It is of a bluish colour, and lamellated texture. It consists of 7-35 tin -f- 2 sulphur. The other sulphuret, or the bisulphuret, is made by heating together the peroxide of tin and sulphur. It ia of a beautiful gold colour, and appears in fine flakes. It was formerly called durum musivum. According to Dr. John Davy, it consists of 1 prime tin 7-35 2 sulphur = 4-00 For another mode of making it, see AURUM MlTSlVtTM. The salts of tin are characterized by the following general properties : 1. Ferroprussiate of potash gives a white precipitate. 2. Hydrosulphuret of potash, a brown- black with the protoxide ; and a golden-yellow with the peroxide. 3. Galls do not affect the solutions of these salts. 4. Corrosive sublimate occasions a black precipitate with the protoxide salts; a white with the peroxide. 5. A plate of lead frequently throws down metallic tin, or its oxide, from the saline so- lutions. 6. Muriate of gold gives, with the prot- oxide solutions, the purple precipitate of Cassius. 7- Muriate of platinum occasions an orange precipitate with die protoxide salts. Concentrated sulphuric acid, assisted by heat, dissolves half its weight of tin, at the same time that sulphurous gas escapes in great plenty. By the addition of water, an oxide of tin is precipitated. Sulphuric acid, slightly diluted, likewise acts upon this metal ; but if much water be present, the solution does not take place. In the sulphuric solution of tin, there is an actual formation or extri- cation of sulphur, which renders the fluid of a brown colour while it continues heated, but subsides by cooling. The tin is likewise precipitated in the form of a white oxide, by a continuance of the heat, or by long standing without heat. This solution affords needle- formed crystals by cooling. Nitric acid and tin combine together very rapidly without the assistance of heat. Most of the metal falls down in the form of a white oxide, extremely difficult of reduction ; and the small portion of tin which remains sus- pended, does not afford crystals, but falls down, for the most part, upon the application of heat to inspissate the fluid. The strong action of the nitric acid upon tin produces a singular phenomenon, which is happily ac- counted for by the modern discoveries in chemistry. M. de Morveau has observed, that, in a solution of tin by the nitric acid, no elastic fluid is disengaged, but ammonia is formed. This alkali must have been pro- duced by the nitrogen of that part of the nitric acid which was employed in affording oxygen to oxidize the tin. The muriatic acid dissolves tin very readily, at the same time that it becomes of a darker colour, and ceases to emit fumes. A slight effervescence takes place with the disengage- ment of a fetid inflammable gas. Muriatic 3 D TIN 770 TIT acid suspends half its weight of tin, and does not let it fall by repose. It affords per- manent crystals by evaporation. If the tin contain arsenic, it remains undissolved at the bottom of the fluid. Recent muriate of tin is a very delicate test of mercury. M. Che- nevix says, if a single drop of a saturated solution of neutralized nitrate, or muriate of mercury, be put into 500 grains of water, a few drops of solution of muriate of tin will render it a little turbid, and of a smoke-gray. He adds, that the effect is perceptible, if ten times as much water be added. Aqua regia, consisting of two parts nitric and one muriatic acid, combines with tin with effervescence, and the development of much heat. In order to obtain a permanent solution of tin in this acid, it is necessary to add the metal by small portions at a time ; so that the one portion may be entirely dissolved before the next piece is added. Aqua regia, in this manner, dissolves half its weight of tin. The solution is of a reddish-brown, and in many instances assumes the form of a concrete gelatinous substance. The addition of water sometimes produces the concrete form in this solution, which is then of an opal colour, on account of the oxide of tin diffused through its substance. The uncertainty attending these experi- ments with the solution of tin in aqua regia, seems to depend upon the want of a sufficient degree of accuracy in ascertaining the specific gravities of the two acids which are mixed, the quantities of each, and of the tin, together with that of the water added. It is probable, that the spontaneous assumption of the con- crete state depends upon water imbibed from the atmosphere. The solution of tin in aqua regia is used by dyers to heighten the colours of cochineal, lac-dye, and some other red tinctures, from crimson to a bright scarlet, in the dyeing of woollens. The acetic acid scarcely acts upon tin. The operation of other acids upon this metal has been little inquired into. Phosphate, fiuate, and borate of tin, have been formed by pre- cipitating the muriate with the respective neutral salts. If the crystals of the saline combination of copper with the nitric acid be grossly pow- dered, moistened, and rolled up in tinfoil, the salt deliquesces, nitrous fumes are emitted, the mass becomes hot, and suddenly takes fire. In this experiment, the rapid transition of the nitric acid to the tin is supposed to produce or develope heat enough to set fire to the nitric salts; but by what particular changes of capacity, has not been shown. If small pieces of phosphorus be thrown on tin in fusion, it will take up from 15 to 20 per cent, and form a silvery white phosphuret of a foliated texture, and soft enough to be cut with a knife, though but little malleable. This phosphuret may be formed likewise by fusing tin filings with concrete phosphoric acid. Tin unites with bismuth by fusion, and becomes harder and more brittle in proportion to the quantity of that metal added. With nickel it forms a white brilliant mass. It cannot easily be united in the direct way with arsenic, on account of the volatility of this metal ; but by heating it with the combination of the arsenical acid and potash, the salt is partly decomposed ; and the tin combining with the acid, becomes converted into a bril- liant brittle compound, of a plaited texture. It has been said, that all tin contains arsenic ; and that the crackling noise which is heard upon bending pieces of tin, is produced by this impurity ; but, from the experiment of Bayen, this appears not to be the fact. Cobalt unites with tin by fusion ; and forms a grained mixture of a colour slightly inclining to violet. Zinc unites very well with tin, increasing its hardness, and diminishing its ductility, in proportion as the quantity of zinc is greater. This is one of the principal additions used in making pewter, which consists for the most part of tin. The best pewter does not contain above one-twentieth part of admixture, which consists of zinc, copper, bismuth, or such other metallic substances as experience has shown to be most conducive to the improvement of its hardness and colour. The inferior sorts of pewter, more especially those used abroad, contain much lead, have a bluish colour, and are soft. The tin usually met with in com- merce in this country, has no admixture to impair its purity, except such as may acci- dentally elude the workmen at the mines. But the tin met with in foreign countries is so much debased by the dealers in that article, especially the Dutch, that pewter and tin are considered abroad as the same substance. Antimony forms a very brittle hard mixture with tin ; the specific gravity of which is less than would have been deduced by computa- tion from the specific gravities and quantities of each, separately taken. Tungsten fused with twice its weight of tin, affords a brown spongy mass, which is somewhat ductile. The uses of tin are very numerous, and so well known, that they scarcely need be pointed out. Several of them have been already men- tioned. The tinning of iron and copper, the silvering of looking-glasses, and the fabrica- tion of a great variety of vessels and utensils for domestic and other uses, are among the advantages derived from this metal. TINCAL. Crude borax, as it is imported from the East Indies, in yellow greasy crys- tals, is called tincal. TINGLASS. Bismuth. TINNING. See IRON. TITANIFEROUS CERITE. A mineral from the Coromandel coast, of a blackish- brown colour, a vitreous conchoidal fracture, hardness equal to that of the gadolinite, and TIT 771 TIT swelling up when heated. Doth alkalis and acids act upon it. Its constituents are, oxide of cerium 30, oxide of iron 19, lime 8, alu- mina 6, water 11, oxide of manganese 1-8, silica 19, oxide of titanium 8. These quan- tities exceed 100 by 9.55 parts, an excess oc- casioned by the protoxide of cerium in the mineral becoming peroxide in the analysis. Laugler. Annalcs de Chim. et Pht/s. xxvii. 313. TITANITES. This name has been given to certain ores of titanium, containing that metal in the state of oxide. See the following article. TITANIUM. The Rev. Mr. Gregor dis- covered in a kind of ferruginous sand, found in the vale of Menachan, in Cornwall, what he supposed to be the oxide of a new metal, but was unable to reduce. Klaproth, afterward analyzing what was called the red schorl of Hungary, found it to be the pure oxide of a new metal, which he named titanium, and the same with the mena- chanite of Mr. Gregor. Since that, oxide of titanium has been discovered in several fossils. We do not know that titanium has been completely reduced, except by Lampadius, who effected it by means of charcoal only. The oxide he employed was obtained from the decomposition of gallate of titanium by fixed alkali. The metal was of a dark copper colour, with much metallic brilliancy, brittle, and in small scales considerably elastic. It tarnishes in the air, and is easily oxidized by heat It then acquires a bluish aspect. It detonates with nitre, and is highly infusible. All the dense acids act upon it with consider- able energy. According to Vauquelin, it is volatilized by intense heat. Certain small cubes occasionally observed in iron slag, had generally been regarded as pyritical, but upon minute inspection, Dr. Wollaston observed, that neither their colour, crystallization, nor hardness, were those of pyrites. The crystals are striated. Purified from iron by muriatic acid, they are insoluble in muriatic, nitric, nitro-muriatic, and sul- phuric acids. Their perfect solution may be effected by the combined action of nitre and borax, since the latter dissolves the oxide as fast as it is formed, and presents a succession of clear surfaces for fresh oxidation. But as these salts do not unite by fusion, the addition of soda, as a medium of union, shortens the pro- cess. The fused mass becomes opaque on cooling by the deposition of a white oxide, which may either be previously freed of the salts by boiling water, and then dissolved in muriatic acid, or the whole mass may be at once dissolved together. In either case, al- kalis precipitate from the solution a white oxide, which is not soluble by excess of al- kali either pure or carbonated. By evaporat- ing the muriatic solution of the oxide to dry- ness, at the heat of boiling water, it is freed of any redundant acid, and the muriate which remains is perfectly soluble in water, and in a state most favourable for exhibiting the cha- racteristic properties of the metal. Infusion of galls gives the well-known red colour of gallate of titanium. The colour occasioned by prussiate of potash is also red, differing from prussiate of copper, by inclining to orange instead of purple, while the colour of prussiate of uranium is rather brown than red. The above crystals are perfect conductors of electricity. Titanium shows no affinity for iron ; and it seems equally indisposed to unite with every other metal that Dr. Wollas- ton tiled. The specific gravity of the metallic titanium is 5-3 ; and it is so hard as to scratch agate. Dr. Wollaston. in Phil. Trans, for 1823. M. Rose obtained oxide of titanium by fusing powdered rutilite with thrice its weight of carbonate of potash, dissolving the com- pound in muriatic acid, precipitating by caus- tic ammonia, digesting the precipitate for a certain time with hydrosulphuret of ammonia, and finally digesting the solid matter left in weak muriatic acid, which leaves the oxide of titanium pure. In this way only, as yet, can the iron be removed. The pure oxide remains perfectly white when heated and cooled, and is then untouched by acids. Fused with car- bonate of potash, and then treated with mu- riatic acid, it sometimes gelatinizes, though not so strongly as silica. It becomes red by touching moist litmus, and with alkalis acts precisely as an acid. It has therefore been called by M. Rose titanic acid. There are no salts with base of titanic acid ; those that have been taken for such, resulted from the presence of alkali in the titanic acid. See ACID (Ti- TANIC). The native red oxide is insoluble in the sulphuric, nitric, muriatic, and nitro-muriatic acids : but if it be fused with six parts of car- bonate of potash, the oxide is dissolved with effervescence. The sulphuric solution when evaporated becomes gelatinous ; the nitric af- fords rhomboidal crystals by spontaneous eva- poration, but is rendered turbid by ebullition ; the muriatic becomes gelatinous, or flocculent, by heat, and transparent crystals form in it when cooled ; but if it be boiled, oxygenized muriatic acid gas is evolved, and a white oxide thrown down. Phosphoric and arsenic acids take it from the others, and form with it a white precipitate. These precipitates are so- luble in muriatic acid, but in no other. The solutions of titanium give white pre- cipitates with the alkalis, or their carbonates ; tincture of galls gives a brownish-red, arid prussiate of potash a brownish yellow. If the prussiate produce a green precipitate, this, ac- cording to Lowitz, is owing to the presence of iron. Zinc immersed in the solutions changes their colour from yellow to violet, and ulti- mately to an indigo ; tin produces in them a 3D2 TOL 772 TOP pale red tint, which deepens to a bright pur- ple red. Hydrosulphuret of potash throws down a brownish-red precipitate, but they are not decomposed by sulphuretted hydrogen. By exposing phosphate of titanium, mixed with charcoal arid borax, to a violent heat, in a double crucible luted, M. Chenevix obtained a pale white phosphuret, with some lustre, brittle, of a granular texture, and not very fusible. The oxides of iron and titanium, exposed to heat with a little oil and charcoal, produce an alloy of a gray colour, intermixed with brilliant metallic particles of a golden yellow. Oxide of titanium was used to give a brown or yellow colour in painting on porcelain, be- fore its nature was known ; but it was found difficult to obtain from it an uniform tint, pro- bably from its not being in a state of purity. TOBACCO. The expressed juice of the leaves, according to Vauquelin, contains the following substances : A considerable quantity of vegetable albu- men or gluten ; supermalate of lime ; acetic acid. A notable quantity of nitrate and muriate of potash. A red matter soluble in alcohol and water, which swells considerably when heated. Muriate of ammonia. . Nicotin. Green fecula, composed chiefly of gluten, green resin, and woody fibre. TOLU (BALSAM OF). This substance is obtained from the toluifera balsamum, a tree which grows in South America. The balsam flows from incisions made in the bark. It comes to Europe in small gourd shells. It is of a reddish-brown colour and considerable consistence ; and when exposed to the air, it becomes solid and brittle. Its smell is fra- grant, and continues so, even after the balsam has become thick by age. When distilled with water, it yields very little volatile oil, but impregnates the water strongly with its taste and smell. A quantity of benzoic acid sublimes, if the distillation be continued. Mr. Hatchett found it soluble in the alkalis, like the rest of the balsams. When he dis- solved it in the smallest possible quantity of lixivium -of potash, it completely lost its own odour, and assumed a fragrant smell, some- what resembling that of the clove-pink. " This smell," Mr. Hatchett observes, "is not fugi- tive, for it is still retained by a solution which was prepared in June, and has remained in an open glass during four months." When digested hi sulphuric acid, a con- siderable quantity of pure benzoic acid sub- limes. When the solution of it in this acid is evaporated to dryness, and the residuum treated with alcohol, a portion of artificial tannin is obtained: the residual charcoal amounts to 0.54 of the original balsam. Mr. Hatchett found, that it dissolved in nitric acid, with nearly the same phenomena as the resins; but it assumed the smell ef bitter almonds, which led him to suspect the formation of prussic acid. During the solu- tion in nitric acid, a portion of benzoic acid sublimes. By repeated digestions, it is con- verted into artificial tannin. It is totally soluble in alcohol, from which water separates the whole of it, except the benzoic acid. TOMBAC. A white alloy of copper with arsenic, commonly brittle, though if the quan- tity of arsenic be small, it is both ductile and malleable in a certain degree. It is sometimes called white copper. TOPAZ. According to Professor Jame- son, this mineral species contains three sub- species, common topaz, schorlite, and physa- lite. Common topaz. Colour wine-yellow. In granular concretions, disseminated and crys- tallized. Its primitive form is an oblique prism of 124 22'. The following are se- condary forms. An oblique four-sided prism, acuminated by four planes ; the same, with the acute lateral edges bevelled ; the same, with a double acumination ; and several other modifications, for which consult Jameson's Min. voL i. p. 75. The lateral planes are longitudinally streaked. Splendent and vi- treous. Cleavage perfect and perpendicular to the axis of the prism. Fracture, small conchoidal. Transparent. Refracts double. Harder than quartz, or emerald ; but softer than corundum. Easily frangible. Sp. gr. 3-4 to 3-6. Saxon topaz in a gentle heat becomes white, but a strong heat deprives it of lustre and transparency. The Brazilian, on the contrary, by exposure to a high temperature, burns rose-red, and in a still higher violet-blue. Before the blowpipe, it is infusible. The topaz of Brazil, Siberia, Mucla in Asia- Minor, and Saxony, when heated, exhibit at one extremity positive, and at the other ne- gative, electricity. It also becomes electrical by friction; and retains its electricity very long. Its constituents are, Braz. Top. Sax. T. Sax. T. Alumina, 58-38 57-45 59 Silica, 3401 3424 35 Fluoric acid, 7-79 7-75 5 100-18 09-44 99 Bcrzi'lius. K/iipr. Klapr. Topaz forms an essential constituent of a particular mountain-rock, which is an aggre- gate of topaz, quartz, and schorl, and is named topaz-rock. Topaz occurs in drusy cavities in granite. It has been also discovered in nests, in transition clay. slate ; and it is found in rolled pieces in alluvial soil. It occurs in large crystals, and rolled masses, in an alluvial soil, in the granite and gneiss districts of Mar and Cairngorm, in the upper parts of Aber- TOU 773 TRA deenshire ; and in veins, along with tin-stone, in clay-slate at St. Anne's, Cornwall. On the continent it appears most abundantly in topaz-rock at Schneckenstein. Jameson. TOPAZOLITE. A variety of precious garnet, found at Mussa in Piedmont. TORRELITE. A new mineral from Sussex county, New Jersey. Colour, dull vermilion red; fracture granular, fine or coarse. Scratches glass. Powder, rose-red. Affects the magnet slightly. Effervesces with acids. Forms with borax a glass that is green while hot, but colourless on cooling. Infusible alone at the blowpipe. Its consti- tuents are, Silica, f.ji-.jt 16-30 Perox. of cerium, 6-16 Protox. of iron, 10-50 Alumina, 1-84 Lime, 1204 Water, - . 175 Loss, . 1-41 50-00 Mr. Children has proved, that the mineral of Dr. Torrey contains manganese, of which his analysis takes no account ; and neither he nor Mr. Faraday could find any cerium in it. Annals of Phil, ix. 217. TORTOISE-SHELL. It approaches to nail or coagulated albumen in its composition. 500 parts, after incineration, leave three of earthy matter, consisting of phosphate of lime, and soda, with a little iron. TOUCHSTONE. Lydian stone, a va- riety of flinty -slate. TOURMALINE. Rhomboidal tourma- line is divided into two sub-species, schorl, and tourmaline. Tourmaline. Colours green and brown. In prismatic concretions, rolled pieces, but generally crystallized. Primitive form, a rhomboid of 133 26'. It occurs in an equi- angular three-sided prism, flatly acuminated on the extremities with three planes. The lateral edges are frequently bevelled, and thus a nine-sided prism is formed : when the edges of the bevelment are truncated, a twelve-sided prism is formed; and when the bevelling planes increase so much that the original faces of the prism disappear, an equiangular six- sided prism is formed. Sometimes the prism is nearly wanting, when a double three-sided pyramid is formed. The lateral planes are generally cylindrical convex, and deeply lon- gitudinally streaked. Crystals embedded. Splendent, vitreous. Cleavage threefold. Fracture conchoidal. Opaque to transparent. Refracts double. When viewed perpendicular to the axis of the crystal, it is more or less transparent, but in the direction of the axis, even when the length of the prism is less than the thickness, it is opaque. As hard as quartz. Easily frangible. Sp. gr. 3-0 to 3-2. By friction it yields vitreous electricity ; by heat- ing, vitreous at one end, and resinous at the ' other. The brown and hyacinth-red varieties have these properties in the greatest degree. The ancients called it lyncurium. Before the blowpipe, it melts into a grayish-white vesi- cular enamel. Its constituents are, silica 42, alumina 40, soda 10, oxide of manganese with a little iron 7, loss 1. Vauqudin. It occurs in gneiss, mica-slate, talc-slate, &c. The red occurs in Siberia, Ava, and Ceylon Jameson. TRACK Y TE. A rock of igneous origin, principally composed of felspar, and conse- quently fusible into a white or slightly co- loured enamel. It has generally a porpliy- ritic structure. See D' ' Aubuisson" 's Geologic, ii. 524. TRAGACANTH (GUM). This sub- stance, which is vulgarly called gum-dragon, exudes from a prickly bush, the astragalus tragacantha, Linn, which grows wild in the warmer climates, and endures the cold of our own, but does not here yield any gum. This commodity is brought chiefly from Turkey, in irregular lumps, or long vermicular pieces bent into a variety of shapes ; the best sort is white, semitransparent, dry, yet somewhat soft to the touch. Gum-tragacanth differs from all the other known gums, in giving a thick consistence to a much larger quantity of water ; and in being much more difficultly soluble, or rather dis- solving only imperfectly. Put into water it slowly imbibes a great quantity of the liquid, swells into a large volume, and forms a soft but not fluid mucilage; if more water be added, a fluid solution may be obtained by agitation ; but the liquor looks turbid and wheyish, and on standing, the mucilage sub- sides, the limpid water on the surface retain- ing little of the gum. Nor does the admix- ture of the preceding more soluble gums pro- mote its union with the water, or render its dissolution more durable: when gum-traga- canth and gum-arabic are dissolved together in water, the tragacanth seems to separate from the mixture more speedily than when dissolved by itself. Tragacanth is usually preferred to the other gums for making up troches, and other like purposes, and is supposed likewise to be the most effectual as a medicine ; but on account of its imperfect solubility, is unfit for liquid forms. It is commonly given in powder with the addition of other materials of similar in- tention ; thus, to one part of gum-tragacanth are added one of gum-arabic, one of starch, and six of sugar. See CERASIN. According to Bucholz, gum-tragacanth is composed of 57 parts of a matter similar to gum-arabic, and 43 parts of a peculiar sub- stance, capable of swelling in cold water without dissolving, and assuming the appear- ance of a thick jelly. It is soluble in boiling water, and then forms a mucilaginous solu- tion. TRE 774 TUN TRAP FORMATIONS in geology. Primitive trap. The name trap is derived from the Swedish word trappa, a stair. Wer- ner understands by trap, rocks principally characterized by the presence of hornblende, and black iron clay. Hence all rocks occur- ring in the primitive class, having hornblende as a characteristic, or predominating ingredient, belong to the primitive trap formation. The following table from Professor Jameson ex- hibits the rocks of this formation. 1. Common hornblende rock. a. Granular hornblende rock. b. Hornblende slate. 2. Hornblende mixed with felspar. a. Greenstone. a. Common greenstone. B' Porphyritic greenstone. y. Greenstone porphyry. 5. Green porphyry. &. Greenstone slate. 3. Hornblende mixed with mica. Transition trap. It contains greenstone and amygdaloid. The newest floctz-trap contains several rocks which are peculiar to it, and others that occur in other floetz formations. The peculiar or characteristic rocks are, basalt, tvacke, gray, stone, porphyry-slate, and traptuff. These, and also greenstone, are often called whins tone by mineralogists. TRAP-TUFF. It is composed of masses of basalt, amygdaloid, hornblende rock, sand- stone, and even pieces of wood (as in the island of Canna) cemented together by a rather loose spongy clayey basis, which has been formed from decomposed basalt or wacke rock. The masses vary much in size, from that of a pea, to several hundred weight. It occurs in beds, which are from a few inches to several fathoms thick. A considerable portion of Arthur's Seat, near Edinburgh, is composed of this rock : there it rests on inclined strata which belong to the oldest coal formation. It occurs also in Mull, and many other places in Scot- land. TRAUMATE. The name given by the French geologists to graywacke. TREMOLITE. This sub-species of straight-edged augite is divided into three kinds ; the asbestous, common, and glassy. 1. Asbestous trcmolite. Colour grayish- white. Massive, and in fibrous concretions. Shining, pearly. Fragments splintery. Trans- lucent on the edges. Rather easily frangible. Soit. Rather sectile. When struck gently, or rubbed in the dark, it emits a pale reddish light ; when pounded and thrown on coals, a greenish light. Before the blowpipe, it melts into a white opaque mass. It occurs most frequently in granular foliated limestone, or in dolomite. It is found in the former in Glentilt and Glenelg ; in the latter, in Aber- deenshire and Icolmkill ; and in basalt in the Castle rock of Edinburgh. 2. Common tremollte. Colour white. Mas- sive, in distinct prismatic concretions, and crystallized in a very oblique four-sided prism, truncated or bevelled on the lateral edges ; in an extremely oblique four-sided prism, perfect, or variously modified by bevelment or trun- cation. The lateral planes are longitudinally streaked. Vitreous or pearly. Cleavage double oblique angular, of 124 50' and 55 50'. Fracture uneven or conchoidal. Trans- lucent. As hard as hornblende. Rather brittle. Sp. gr. 2-9 to 3-2. It melts with much difficulty and ebullition into an opaque glass. Its constituents are, silica 50, mag- nesia 25, lime 18, carbonic acid and water 5. Laugier. It occurs with the preceding. 3. Glassy trcmolite. Colour grayish, green- ish, yellowish, and reddish -white. Massive, in distinct concretions, and frequently crys- tallized in long acicular crystals. Shining, between vitreous and pearly. Translucent. As hard as hornblende. Very brittle. Sp. gr. 2-863. It is phosphurescent in a low degree. Infusible. Its constituents are, silica 35-5, lime 26-5, magnesia 16-5, water and carbonic acid 23. Laugier. It occurs with the preceding. Jameson. TRIPHANE. See SPODUMENE. TRIPOLI. Colour yellowish -gray. Mas- sive. Fracture fine or coarse earthy. Opaque. Soft. Rather easily frangible. Meagre. Does not adhere to the tongue. Sp. gr. 2-2. In- fusible. Its constituents are, silica 81, alu- mina 1-5, oxide of iron 8, sulphuric acid 3-45, water 4-55. Bucholz. Of the rottenstone, silica 4, alumina 86, carbon 10. Phillips. It occurs in beds in coal-fields, with secondary limestone, and under basalt. It is found at Bakewell, in Derbyshire, where it is called rottcnstone. It is used for polishing stones, metals, and glasses. The tripoli of Corfu is reckoned the most valuable. TRONA. The name given in Africa to the native carbonate of soda, found at Sukena, near Fezzan. TUBE OF SAFETY. A tube open at both ends, inserted into a receiver, the upper end communicating with the external air, and the lower being immersed in water. Its in- tention is to prevent injury from too sudden condensation or rarefaction taking place dur- ing an operation. For, if a vacuum be pro- duced within the vessels, the external air will enter through the tube : and if air be gene- rated, the water will yield to the pressure, being forced up the tube. Thus, too, the height of the water in the tube indicates the degree of pressure from the confined gas or gases. See PI. VII. fig. 3. h. It is now more frequently used in a curved form, ib. fig. 1 . ; and is commonly called a Welter's tube. TUFACEOUS LIMESTONE, or CALC TUFF. See LIMESTONE. TUMITE. See THUMMERSTONE. TUNGSTEN. See ORES OF TUNGSTEN. TUN 775 TUR TUNGSTENUM. This name, signify, ing heavy stone, was given by the Swedes to a mineral, which Scheele found to contain a peculiar metal, as he supposed, in the state of an acid, united with lime. The same metallic substance was afterwards found by the Don d'Elhuyarts united with iron and manganese in wolfram. From the first of these the oxide may be obtained by digesting its powder in thrice its weight of nitric acid; washing the yellow powder that remains, and digesting it in am- monia, by which a portion of it is dissolved. These alternate digestions are to be repeated, and the tungstic oxide precipitated from the ammoniacal solutions by nitric acid. The precipitate is to be washed with water, and exposed to a moderate heat, to expel any am- monia that may adhere to it. Or the mixture may be evaporated to a dry mass, which is to be calcined under a muffle, to dissipate the nitrate of ammonia. From wolfram it may be obtained by the same process, after the iron and manganese have been dissolved by muriatic acid. The Spanish chemists reduced the oxide of tungsten to the metallic state, by exposing it, moistened with oil, in a crucible lined with charcoal, to an intense heat. After two hours a piece of metal weighing 40 grains, but slightly agglutinated, was found at the bottom of the crucible. Some have attempted its reduction in vain, but Guyton, Ruprecht, and Messrs. Aikin and Allen, have been more successful. The latter gentlemen produced it from the am- moniuret. From 240 grains of this substance, in acicular crystals, exposed for two hours to a powerful wind-furnace, in a crucible lined with charcoal, they obtained a slightly cohering mass of roundish grains, about the size of a pin's head, with a very brilliant metallic lustre, and weighing in the whole 161 grains. Tungsten is said to be of a grayish-white or iron colour, with considerable brilliancy, very hard and brittle. Its specific gravity Don d'Elhuyarts found to be 17-6 ; Messrs. Aiken and Allen, above 17-22. There are two oxides of tungstenum, the brown, and the yellow or tungstic acid. The brown oxide is formed by transmitting hydrogen gas over tungstic acid, in an ignited glass tube. It has a flea-brown colour, and when heated in the air, it takes fire and burns like tinder, passing into tungstic acids which see. The brown oxide consists of Tungstenum, 100 Oxygen, 16-6. Berzd Hence, if we regard it as composed of 2 primes oxygen -f- 1 metal, its composition will be Tungstenum, 12.05 100 Oxygen, 2-00 16-6 Hence the acid prime ought probably to be 12-06 + 3 = 15-05 or 15; and that of the metal 12. But from Berzelius's experiments, tungstate of lime seems to consist of Tungstic acid, 100 14-50 Lime, 24-12 3-50 The difference indeed is not great. Sir H. Davy found that tungstenum burns with a deep red light, when heated in chlorine,, and forms an orange-coloured volatile sub- stance, which affords the yellow oxide of tungs- tenum, and muriatic acid, when decomposed by water. Scheele supposed the white powder obtained by digesting the ore in an acid, adding am- monia to the residuum, and neutralizing it by nitric acid, to be pure acid of tungsten. In fact it has a sour taste, reddens litmus, forms neutral crystallizable salts with alkalis, and is soluble in 20 parts of boiling water. It ap- pears however to be a triple salt, composed of nitric acid, ammonia, and oxide of tungsten ; from which the oxide may be obtained in a yellow powder, by boiling with a pure con- centrated acid. In this state it contains about 20 per cent, of oxygen ; part of which may be expelled by a red heat, when it assumes a green colour. Tungsten is insoluble in the acids ; and its oxide is nearly the same. It appears to be capable of uniting with most other metals, but not with sulphur. Guyton found that the oxide gives great permanence to vegetable colours. M. Wohler has written a memoir on tungs- ten and its combinations in the Annales de Ckimie, xxix. 43. Oxide of tungsten inflames in the air, and becomes tungstic acid. 100 of the former absorb 8 of oxygen ; while 100 of metallic tungsten absorb 25 in becoming tungstic acid. M. Wohler describes 3 chlorides of tungsten. TUNGSTEN OF BASTNAS,or FALSE TUNGSTEN. See CERIUM. TURBETH MINERAL. Yellow sub- deutosulphate of mercury. TURNSOLE. Heliotropium. See AR- CHIL. TURKEY STONE. Cos Turcica. See WHETSLATE. TURMERIC (terra merita), curcuma longa, is a root brought to us from the East Indies. Berthollet had an opportunity of ex- amining some turmeric that came from To- bago, which was superior to that which is met with in commerce, both in the size of roots and the abundance of the colouring particles. This substance is very rich in colour, and there is no other which gives a yellow colour of such brightness ; but it possesses no durability, nor can mordants give it a sufficient degree. Com- mon salt and sal ammoniac are those which fix the colour best, but they render it deeper and make it incline to brown : some recom- mend a small quantity of muriatic acid. The TUR 776 TYP root must be reduced to powder to be fit for use. It is sometimes employed to give' the yellows made with weld a gold cast, and to give an orange tinge to scarlet ; but the shade the turmeric imparts soon disappears in the air. Mr. Guchliche gives two processes for fix- ing the colour of turmeric on silk. The first consists in aluming in the cold for twelve hours a pound of silk in a solution of two ounces of alum, and dyeing it hot, but with- out boiling, in a bath composed of two ounces of turmeric and a quart (measure) of aceto- citric acid, mixed with three quarts of water. The second process consists in extracting the colouring particles from the turmeric by aceto- citric acid, in the way described for Brazil wood, and in dyeing the silk alumed as already mentioned in this liquor, either cold or only moderately warm. The colour is rendered more durable by this than by the former pro- cess. The first parcel immersed acquires a gold yellow; the colour of the second and third parcels is lighter, but of the same kind ; that of the fourth is a straw colour. Mr. Guchliche employs the same process to extract fine and durable colours from fustic, broom, and French berries ; he prepares the wool by a slight aluming, to which he adds a little muriatic acid. He seems to content himself in these cases with vinegar or some other ve- getable acid, instead of his aceto-citric acid, for the extraction of the colour ; he directs that a very small quantity of solution of tin should be put into the dye-bath. TURNERITE. A rare mineral in small crystals of a yellowish-brown, or brownish- yellow-colour. Brilliant. Primary form an oblique rhombic prism. Scratches fluor, but yields to the knife. Powder grayish-white. It contains alumina, lime, magnesia, and a very little iron. It has been found only on Mount Sorel in Dauphiny. TURPENTINE is a resinous juice ex- tracted from several trees. Sixteen ounces of Venice turpentine, being distilled with water, yielded four ounces and three drachms of essential oil ; and the same quantity, distilled without water, yielded with the heat of a water- bath, two ounces only. When turpentine is distilled or boiled with water till it becomes solid, it appears yellowish ; when the process is farther continued, it acquires a reddish- brown colour. On distilling sixteen ounces in a retort with an open fire, increased by de- grees, Neumann obtained, first, four ounces of a limpid colourless oil; then two ounces and a drachm of a dark brownish-red em- pyreumatic oil, of the consistence of a bal- sam, and commonly distinguished by that name. The essential oil, commonly called spirit of turpentine, cannot without singular difficulty be dissolved in alcohol, though turpentine itself is easily soluble in that spirit. One part of the oil may be dissolved in seven parts of alcohol ; but on standing a while, the greatest part of the oil separates and falls to the bottom. TURQUOIS (MINERAL), OR CA- LAITE. Colours smalt-blue and apple- green. Massive, disseminated, and imitative. Dull. Fracture conchoidal or uneven. Opaque. Harder than felspar, but softer than quartz. Streak white. Sp. gr. 2-86 to 3-0. Its con- stituents are, alumina 73, oxide of copper 4-5, water 18, oxide of iron 4. John. It occurs in veins in clay-ironstone, and in small pieces in alluvial clay. It has been found only in the neighbourhood of Nichabour in the Kho- rassan, in Persia. It is very highly prized as an ornamental stone in Persia, and the neigh- bouring countries. Malchite yields a green streak, but that of calaite is white. Bone tur- quois is phosphate of lime, coloured with oxide of copper. *TUTENAG. This name is given in India to the metal zinc. It is sometimes ap- plied to denote a white metallic compound, brought from China, called also Chinese cop- per, the art of making which is not known in Europe. It is very tough, strong, malleable, may be easily cast, hammered, and polished ; and the better kinds of it, when well manu- factured, are very white, and not more dis- posed to tarnish than silver is. Three in- gredients of this compound may be discovered by analysis ; namely, copper, zinc, and iron. Some of the Chinese white copper is said to be merely copper and arsenic. TYPE METAL. The basis of type me- tal for printers is lead, and the principal arti- cle used in communicating hardness is anti- mony, to which copper and brass in various proportions are added. The properties of a good type metal are, that it should run freely into the mould, and possess hardness without being excessively brittle. The smaller letters are made of a harder composition than those of a larger size. It does not appear that our type-founders are in possession of a good com- position for this purpose. The principal de- fect of their composition appears to be, that the metals do not uniformly unite. In a piece of casting performed at one of our principal founderies, the thickness of which was two inches, I found one side hard and brittle when scraped, and the other side, consisting of nearly half the piece, was soft like lead. The tran- sition from soft to hard was sudden, not gra- dual. If a parcel of letter of the same size and casting be examined, some of them are brittle and hard, and resist the knife, but others may be bent and cut into shavings. It may easily be imagined, that the duration and neatness of these types must considerably vary. I have been informed, but do not know the fact from trial, that the types cast in Scot- land are harder and more uniform in their qualities . Nicholson . ULM 777 URA U ULMIN. This name has been given to a very singular substance lately examined by Klaproth. It differs essentially from every other known body, and must therefore consti- tute a new and peculiar vegetable principle. It exuded spontaneously from the trunk of a species of elm, which Klaproth conjectures to be the nlmus nigra^ and was sent to him from Palermo in 1802. 1. In its external characters it resembles gum. It was solid, hard, of a black colour, and had considerable lustre. Its powder was brown. It dissolved readily in the mouth, and was insipid. 2. It dissolved speedily in a small quantity of water. The solution was transparent, of a blackish-brown colour, and, even when very much concentrated by evaporation, was not in the least mucilaginous or ropy; nor did it answer as a paste. In this respect ulmin differs essentially from gum. 3. It was completely insoluble both in al- cohol and ether. When alcohol was poured into the aqueous solution, the greater part of the ulmin precipitated in light brown flakes. The remainder was obtained by evaporation, and was not sensibly soluble in alcohol. The alco- hol by this treatment acquired a sharpish taste. 4. When a few drops of nitric acid were added to the aqueous solution, it became ge- latinous, lost its blackish -brown colour, and a light brown substance precipitated. The whole solution was slowly evaporated to dry- ness, and the reddish-brown powder which re- mained was treated with alcohol. The alcohol assumed a golden-yellow colour ; and, when evaporated, left a light brown, bitter, and sharp resinous substance. 5. Oxymuriatic acid produced precisely the same effects as nitric. Thus it appears that ulmin, by the addition of a little oxy- gen, is converted into a resinous substance. In this new state it is insoluble in water. This property is very singular. Hitherto the volatile oils were the only substances known to assume the form of resins. That a substance soluble in water should assume the resinous form with such facility, is very remarkable. 6. Ulmin when burnt emitted little smoke or flame, and left a spongy but firm char- coal, which, when burnt in the open air, left only a little carbonate of potash behind. Such are the properties of this curious sub- stance, as far as they have been examined by Klaproth. M. Dobereiner says that gallic acid is con- vertible into ulmin, by combining the acid with ammonia, and exposing the compound to oxygen Ann. de Chim. xxiv. 353. ULTRAMARINE. See AZURE-STONE. UMBER. See ORES OF IRON. URANGLIMMER. An ore of ura- nium, formerly called green mica, and by Werner chalcolite. See the following ar- ticle. URANITE, OR URANIUM. A new metallic substance, discovered by the cele- brated Klaproth, in the mineral called Pech- llende. In this it is in the state of sulphuret. But it likewise occurs as an oxide in the green mica, or uranglimmer, and in the ura- nochre. By treating the ores of the metal with the nitric or nitro-muriatic acid, the oxide will be dissolved; and may be precipitated by the addition of a caustic alkali. It is in- soluble in water, and of a yellow colour; but a strong heat renders it of a brownish, gray. To obtain it pure, the ore should be treated with nitric acid, the solution evaporated to dryness, and the residuum heated, so as to render any iron it may contain insoluble. This being treated with distilled water, ammonia is to be poured into the solution, and digested with it for some time, which will precipitate the uranium and retain the copper. The pre- cipitate, well washed with ammonia, is to be dis- solved in nitric acid, and crystallized. The green crystals, dried on blotting paper, are to be dis- solved in water, and recrystallized, so as to get rid of the lime. Lastly, the nitrate, being exposed to a red heat, will be converted into the yellow oxide of uranium. It is very difficult of reduction. Fifty grains, after being ignited, were formed into a ball with wax, and exposed, in a well closed charcoal crucible, to the most vehement heat of a porcelain furnace, the intensity of which gave 170 on Wedgewood's pyrometer. Thus a metallic button was obtained, weighing 28 grains, of a dark-gray colour, hard, firmly co- hering, fine grained, of very minute pores, and externally glittering. On filing it, or rubbing it with another hard body, the metallic lustre has an iron-gray colour ; but in less perfect essays it verges to a brown. Its specific gravity was 8*1. Bucholz, however, obtained it as high as 9.0. There are probably but two oxides of ura- nium ; the protoxide, which is grayish-black ; and the peroxide, which is yellow. When uranium is heated to redness in an open vessel, it glows like a live coal, and passes into the protoxide, which, from the experi- ments of Schoubert, consists of Uranium, 100 15.7 Oxygen, 6.3?3 1-0 The precipitate thrown down by potash from URA 778 URA the nitrate solution is called the yelkw oxide. It consists of Uranium, 100 314 = 2 primes Oxygen, 9.359 3-0 = 3 It is generally stated, upon the authority of Bucholz and Schoiibert, that there are two oxides of uranium ; but the following expe- riments appear to render this opinion very doubtful. A quantity of oxide of uranium was pre- pared, as usual, from the native oxide (pech- blende), and converted into nitrate, by solu- tion in nitric acid and crystallization. The crystals were dissolved in water, and were found still slightly contaminated by copper; their solution was therefore decomposed by excess of ammonia, and the precipitated oxide digested in liquid ammonia, until all traces of copper were removed : it was then washed, and dried in a very moderate heat, and was considered as a pure hydrated peroxide of uranium. But this supposed peroxide dissolved very readily in muriatic acid, without the slightest evolution of chlorine, though there was some effervescence arising from the extrication of a small portion of carbonic acid gas. Moreover, the above hydrated oxide, when heated to dull redness in a glass tube, only lost water and a little carbonic acid; it lost no oxygen, but be- came black and cohesive, diminishing exceed- ingly in bulk. A portion heated to bright redness in a platinum crucible, underwent nearly the same changes, contracting into a dark purplish mass, which, however, when triturated into an impalpable powder in an agate mortar, assumed a dingy yellow -brown tint. In this state the oxide of uranium ap- pears only to lose water and a small portion of carbonic acid, accidentally contracted during its precipitation and drying, and not to have altered its state of oxidation, for it remains, as before, perfectly soluble in muriatic and nitric acids, evolving no gas, and forming salts in no respect differing from those produced with the hydrated oxide, recently thrown down from the nitrate. 50 grs. of the yellow hydrated oxide of ura- nium, dried at 212, and afterwards exposed under the exhausted receiver, including a sur- face of sulphuric acid, till it no longer lost weight, were exposed to a white heat, in a pla- tinum capsule. The loss, upon an average of three trials, amounted to 6 grains, so that the composition of the hydrated oxide of ura- nium is 88 oxide 12 water 100 and, assuming this hydrate to consist of 1 proportional of water and 1 of oxide, the prime equivalent of oxide of uranium will be 6G, that of water being 9 ; and 58 will be the equivalent of uranium, if the above oxide be a compound of 1 proportional of metal and 1 of oxygen. II. Oxide of uranium dissolves easily and entirely in muriatic acid, and the solution affords, on evaporation, very deliquescent prismatic crystals, of an olive-green colour: if these be dried by heat, they suffer decom- position; but when dried in the exhausted receiver, by sulphuric acid, they crumbled down into a dirty green powder, which is ex- tremely deliquescent. To ascertain the com- position of this salt, a portion of the neutral muriate was decomposed by caustic ammonia, and the precipitated oxide, dried, ignited, and weighed, amounted to 112 grains. The fil- tered ammonio-muriatic solution was rendered slightly acid by nitric acid, and precipitated by nitrate of silver; it afforded 149-8 grains of chloride of silver, equal to 38 grains of mu- riatic acid. Here, therefore, the muriate of uranium appears to consist of Oxide of uranium, 112 1 00 Muriatic acid, 38 34 Assuming this muriate to consist of 1 pro- portional of muriatic acid = 37, and 1 of oxide of uranium, the equivalent of the latter will be 109, and that of the metal 101. III. The recently precipitated oxide of ura- nium very readily dissolves in nitric acid, and, by careful evaporation, furnishes truncated prismatic crystals of a peculiar iridescent ap- pearance, a brownish-yellow colour, and deli- quescent. A portion of these crystals exposed under the exhausted receiver containing sul- phuric acid, effloresced into a yellow powder, which was retained in vacuo till it ceased to lose weight ; 60 grains were then submitted to a red heat, in a platinum capsule, and 36-4 grains of oxide remained. If, therefore, we regard the above salt as a dry nitrate, it will consist of 36-4 oxide of uranium = 60-7 23-6 nitric acid = 39-3 100 and, if considered as a compound of 1 pro- portional of nitric acid, and 1 of oxide of ura- nium, the number 84 will represent the oxide, and 76 the metal ; but we can put no further reliance in the above numbers than as showing the quantity of oxide in the nitrate, dried as above described, for it is probable that in that state the salt still retains a portion of water, which would vitiate the above estimate. IV. When recently precipitated oxide of uranium is digested in sulphuric acid, diluted with 4 or 5 parts of water, a solution of a green colour is obtained, which has an astrin- gent aluminous taste, and is neutral; but, when evaporated, it deposits successive crusts of a difficultly soluble green salt, probably a subsulphate of uranium, and the supernatant liquor becomes acid, but cannot be made to crystallize. Dilute sulphuric acid was digested upon URA 779 URA moist oxide of uranium, until a perfectly neutral solution was obtained. A portion of this solution was decomposed by caustic am- monia, and the precipitated oxide, duly washed and ignited, weighed 62 grains. The solution from which the above 62 grains of oxide had been thrown down was neutralized by nitric acid, and precipitated by muriate of baryta. It yielded 85 grains of dry sulphate of baryta, which is equivalent to 22 grains of sulphuric acid : here, therefore, it would appear that dry sulphate of uranium consists of 62 oxide = 68-1 29 acid 31-9 . 91 100 and, assuming 40 as the prime equivalent of sulphuric acid, that of oxide of uranium will be 85-6, and of the metal 77-6 ; a number not very different from that obtained by the ana- lysis of the nitrate. V. When solution of nitrate of uranium is decomposed by carbonate of ammonia, a very slight excess of the latter dissolves a con- siderable portion of the precipitate, and which, when collected and dried, appears to retain the carbonic acid very feebly, and not to be of uniform composition, but a mixture of oxide and carbonate. In several experiments, in which the supposed carbonate of uranium was decomposed by muriatic acid over mercury, the proportion of carbonic acid evolved was various. The following is the best experi- ment that was made with the precipitated car- bonate : 30 grains were decomposed over mer- cury, by muriatic acid ; they evolved 2.9 cubic inches of carbonic acid := 1-32 grains; 30 grains of the above carbonate, heated to red- ness, until they ceased to lose weight, lost 3-4 grains. Hence it appears, that 30 grains of the above precipitated carbonate consist of Oxide, 26-6 Acid, 1-32 Water, 2-08 a quantity of carbonic acid infinitely too small to be considered as saturating the oxide. Another attempt was made to obtain a pure carbonate of uranium. A quantity of recently precipitated and moist oxide was diffused through water, and carbonic acid was passed through the mixture, by which the oxide was very soon entirely dissolved. This solution was gently heated, when it presently became turbid, and the precipitate being collected and dried at a very moderate heat, was of a dirty yellow colour, and perfectly soluble, with slight effervescence, in muriatic and nitric acids. When, however, an attempt was made to collect the carbonic acid evolved, it did not amount to 1 cubical inch from 30 grains ; so that it may perhaps be concluded that there is no dry carbonate of uranium which can be regarded as a definite compound. VI. It has been stated above, that when oxide of uranium is boiled with dilute sul- phuric acid, a yellow-green compound, of dif- ficult solubility, is formed, which has there been termed a subsulphate : to determine its composition, 50 grains, carefully washed and dried, were dissolved in nitro-muriatic acid, and the solution decomposed by ammonia; the precipitated oxide of uranium having been separated upon a filter, the clear liquor was precipitated by muriate of baryta, and 29-5 grains of sulphate of baryta, = 10 of sulphuric acid, were obtained ; hence the composition of the subsulphate is, Sulphuric acid, 10 Oxide, 40 50 and if we consider this as composed of 2 pro- portionals of oxide and 1 of acid, we obtain the number 80 as the equivalent of oxide of ura- nium, and 72 as that of the metal. Neither iodine nor the hydriodates occasion any pre- cipitation in solutions of uranium, but fer- rocyanate of potassa occasions a fine reddish- brown precipitate in them all, and this al- though they are considerably acid. The above experiments were undertaken with a view of determining the equivalent number of uranium ; but of the various com- pounds that have been examined, the sulphates only appear to afford results that can be deemed at all satisfactory ; and even these are too much at variance to enable us to assume their analysis as the foundation of a prime equiva- lent number. Journal of Science, xiii. 86. M. Arfwedson procures pure oxide of ura- nium in the following way : Finely pulverized pechblende is to be dissolved by a gentle heat in nitro-muriatic acid, after which a good deal of water is to be added, and a little muriatic acid, if necessary. The undissolved matters are to be removed (sulphur, silica, gangue), and a current of sulphuretted hydrogen gas passed through the solution as long as it affects it. The first precipitate is dark coloured ; but the second being sulphuret of arsenic is yellow. On filtration, the liquor is free from copper, lead, and arsenic ; but contains iron, cobalt, and zinc. It is now to be digested with a little nitric acid to peroxidize the iron, and then decomposed by carbonate of ammonia, in excess, which leaves the iron and earths. The filtered solution is to be boiled as long as car- bonate of ammonia is disengaged ; the oxides of uranium, zinc, with part of the oxide of cobalt, fall down, which are to be collected on a filter and dried. It is then to be heated to redness, by which it becomes of a dark green colour, and afterwards by digestion in dilute muriatic acid has the oxides of cobalt and zinc, with a small portion of oxide of uranium, dissolved out, and after washing and drying, pure oxide of uranium remains. About 65 parts were in this way obtained from 100 of pechblende. The oxide is soluble in dilute sulphuric URE 780 URE acid gently heated, and affords lemon-coloured prismatic crystals. Its solution in muriatic acid, in which it is but imperfectly soluble, affords yellowish-green rhomboidal tablets. Phosphoric acid dissolves it, but after some time the phosphate falls down in a flocculent form, and of a pale yellow colour. It combines with vitrifiable substances, and gives them a brown or green colour. On porcelain, with the usual flux, it produces an orange. URANOCHRE. An ore of uranium, containing this metal in the oxidized state. See the preceding article. URATES. Compounds of uric or lithic acid with the salifiable bases. See ACID (LlTHIC). UREA. The best process for preparing urea is to evaporate urine to the consistence of syrup, taking care to regulate the heat towards the end of the evaporation ; to add very gra- dually to the syrup its volume of nitric acid (24 Baume)of 1-20; to stir the mixture, and immerse it in a bath of iced water, to harden the crystals of the acidulous nitrate of urea which precipitate ; to wash these crystals with ice-cold water, to drain them, and press them between the folds of blotting paper. When we have thus separated the adhering hetero- geneous matters, we redissolve the crystals in water, and add to them a sufficient quantity of carbonate of potash, to neutralize the nitric acid. We must then evaporate the new liquor, at a gentle heat, almost to dryness ; and treat the residuum with a very pure alco- hol, which dissolves only the urea. On con- centrating the alcoholic solution, the urea crystallizes. The preceding is M. Thenard's process, which Dr. Prout has improved. He separates the nitrate of potash by crystallization, makes the liquid urea into a paste with animal char- coal, digests this with cold water, filters, con- centrates, then dissolves the new colourless urea in alcohol, and lastly crystallizes. The process prescribed by Dr. Thomson, in the fifth edition of his System, does not an- swer. Urea crystallizes in four-sided prisms, which are transparent and colourless, with a slight pearly lustre. It has a peculiar but not urinous odour ; it does not affect litmus or turmeric papers ; it undergoes no change from the atmosphere, except a slight deliquescence in very damp weather. In a strong heat it melts, and is partly decomposed and partly sublimed without change. The sp. gr. of the crystals is about 1-35. It is very soluble in water. Alcohol, at the temperature of the atmosphere, dissolves about 20 per cent. ; and when boiling, considerably more than its own weight, from which the urea separates on cooling, in its crystalline form. The fixed alkalis and alkaline earths decompose it. It unites with most of the metallic oxides ; and forms crystalline compounds with the nitric and oxalic acids. If cautiously introduced into a retort with a wide short neck, it fuses with a gentle heat : a white fume rises, which is benzoic acid, and condenses on the sides of the receiver : crystal- lized carbonate of ammonia succeeds, and con- tinues to the end : neither water nor oil rises, but the sublimate is turned brown : the air expelled from the apparatus is impregnated with a smell of garlic and stinking fish : when the heat is very intense, the smell is insup- portable. The matter hi the retort is then dry, blackish, and covered with a raised white crust, which rises at length in a heavy vapour, and attaches itself to the lower part of the re- tort. This is muriate of ammonia. If water be poured on the residuum, it emits a smell of prussic acid. Burned on an open fire it exhales the same smell, gives out ammonia, and leaves one-hundredth of its weight of acrid white ashes, which turn syrup of violets green, and contain a small quantity of carbonate of soda. The aqueous solution, distilled by a gen- tle fire, and carried to ebullition, affords very clear water loaded with ammonia. By adding more water, as the liquor became inspissated, Fourcroy and Vauquelin obtained nearly two- thirds of the weight of the urea in carbonate of ammonia, and the residuum was not then ex- hausted of it. The latter portions, however, were more and more coloured. This decomposition of an animal substance at the low heat of boiling water is very re- markable, particularly with respect to the carbonic acid. Indeed it appears that a very slight change of equilibrium is sufficient to cause its constituent principles to pass into the state of ammonia, and carbonic, prussic, and acetous acids. Urea has been recently analyzed by Dr. Prout and M. Berard. The following are its constituents : Per Cent. Per Cent. Per atom. Hydrogen, 10.80 6.66 2 = 2.5 Carbon, 19.40 19.99 1 = 7-5 Oxygen, 26.40 26.66 1 = 10.0 Azote, 43.40 46.66 1 = 17.5 100.00 100-00 37.5 See SUGAR for some remarks on the re- lation between it and urea. Uric, or lithic acid, is a substance quite distinct from urea in its composition. This fact, according to Dr. Prout, explains, why an excess of urea generally accompanies the phosphoric dia- thesis, and not the lithic. He has several tunes seen urea as abundant in the urine of a person where the phosphoric diathesis pre- vailed, as to crystallize spontaneously on the addition of nitric acid, without being con- centrated by evaporation. As urea and uric acid, says M. Berard, are the most azotized of all animal substances, the URI 781 URI secretion of urine appears to have for its object the separation of the excess of azote from the blood, as respiration separates from it the excess of carbon. Urea has a singular effect on the crystal- lization of some salts. If muriate of soda be dissolved in a solution of urea, it will cry. stallizs by evaporation, not in cubes, but in octaedra ; muriate of ammonia, on the con- trary, treated in the same way, instead of crystallizing in octaedra, will assume the cubic form. The same effect is produced, if fresh urine be employed. URIC ACID. See ACID (LiTHic). URINE. This excrementitious fluid, in its natural state, is transparent, of a yellow colour, a peculiar smell and saline taste. Its production as to quantity, and in some mea- sure quality, depends on the seasons and the peculiar constitution of the individual, and is likewise modified by disease. It is observed, that perspiration carries off more or less of the fluid, which would else have passed off by urine ; so that the profusion of the former is attended with a diminution of the latter. From the alkaline smell of urine kept for a certain time, and other circumstances, it was formerly supposed to be an alkaline fluid ; but by its reddening paper stained blue with litmus or the juice of radishes, it appears to contain an excess of acid. The numerous researches made concerning urine have given the following as its compo- nent parts : 1, water ; 2, urea ; 3, phosphoric acid ; 4, 5, 6, 7> phosphates of lime, mag- nesia, soda, and ammonia; 8, 9, 10, 11, lithic, rosacic, benzoic, and carbonic acid ; 12, carbonate of lime; 13, 14, muriates of soda and ammonia ; 15, gelatin ; 16. albumen ; 17, resin ; 18, sulphur. Muriate of potash may sometimes be de- tected in urine, by cautiously dropping into it some tartaric acid ; as may sulphate of soda, or of lime, by a solution of muriate of barytes, which will throw down sulphate of barytes together with its phosphate ; and these may be separated by a sufficient quantity of mu- riatic acid, which will take up the latter. Urine soon undergoes spontaneous changes, which are more or less speedy and extensive, according to its state, as well as the tempera- ture of the air. Its smell, when fresh made, and healthy, is somewhat fragrant ; but this presently goes off, and is succeeded by a pe- culiar odour termed urinous. A s it begins to be decomposed, its smell is not very unlike that of sour milk ; but this soon changes to a fetid, alkaline odour. It must be observed, however, that turpentine, asparagus, and many other vegetable substances, taken as medicine, or used as food, have a very powerful effect on the smell of the urine. Its tendency to putre- faction depends almost wholly on the quantity of gelatin and albumen it contains ; in many cases, where these are abundant, it comes on very quickly indeed. According to Berzelius, healthy human urine is composed of, water 933, urea 30-10, sulphate of potash 3-71 , sulphate of soda 3-16, phosphate of soda 2-94, muriate of soda 4-45, phosphate of ammonia 1-65, muriate of am- monia 1-50, free acetic acid, with lactate of ammonia, animal matter soluble hi alcohol, urea adhering to the preceding, altogether 17-14, earthy phosphates, with a trace of fluate of lime 1-0, uric acid 1, mucus of the bladder 0-32, silica 0-3, in 1000-0. The phosphate of ammonia and soda, obtained from urine, by removing by alcohol the urea from its crystal- lized salts, was called fusible salt of urine, or microcosmic salt ; and was much employed in experiments with the blowpipe. The changes produced in urine hy disease are considerable, and of importance to be known. It is of a red colour, small in quan- tity, and peculiarly acrid, in inflammatory diseases ; but deposits no sediment on stand- ing. Corrosive muriate of mercury throws down from it a copious precipitate. Toward the termination of such diseases, it becomes more abundant, and deposits a copious pink- coloured sediment, consisting of rosacic acid, with a little phosphate of lime and uric acid. In jaundice it contains a deep yellow co- louring matter, capable of staining linen. Mu- riatic acid renders it green, and this indicates the presence of bile. Sometimes, too, accord- ing to Fourcroy and Vauquelin, it contains a substance analogous to the yellow acid, which they formed by the action of nitric acid on muscular fibre. In hysterical affections it is copious, limpid, and colourless, containing much salt, but scarcely any urea or gelatin. In dropsy the urine is generally loaded -with albumen, so as to become milky, or even coa- gulate by heat, or on the addition of acids. In dropsy from diseased liver, however, no albumen is present ; but the urine is scanty, high coloured, and deposits the pink-coloured sediment. In dyspepsy, or indigestion, the urine abounds in gelatin, and putrefies rapidly. In rickets, the urine contains a great deal of a calcareous salt, which has been supposed to be phosphate of lime, but according to Bon- homme it is the oxalate. Some instances are mentioned, in which females have voided urine of a milky appear- ance, and containing a certain portion of the caseous part of milk. But among the most remarkable alterations of urine is that in the diabetes, when the urine is sometimes so loaded with sugar, as to be capable of being fermented into a vinous liquor. Upwards of one-twelfth of its weight of sugar was extracted from some diabetic urine by Cruickshank, which was at the rate of twenty-nine ounces troy a day from one pa- tient. In this disease, however, the urine, though always in very large quantity, is some- times not sweet, but insipid. VAR 782 VAR The urine of some animals, examined by Fourcroy, Vauquelin, and Rouelle, jun. ap- pears to differ from that of man in wanting the phosphoric and lithic acids, and contain- ing the benzoic. That of the horse, accord- ing to the former two, consists of benzoate of soda .024, carbonate of lime .011, carbonate of soda .009, muriate of potash .009, urea .007, water and mucilage .940. Giese, how- ever, observes, that the proportion of benzoate of soda varies greatly, so that sometimes scarcely any can be found. Notwithstanding the assertions of these chemists, that the urine of the horse contains no phosphoric acid, Gio- bert affirms that phosphorus may be made from it. That of the cow, according to Rouelle, con- tains carbonate, sulphate, and muriate of pot- ash, benzoic acid, and urea : that of the camel differed from it in affording no benzoic acid : that of the rabbit, according to Vauquelin, contains the carbonates of lime, magnesia, and potash, sulphates of potash and lime, muriate of potash, urea, gelatin, and sulphur. All these appear to contain some free alkali, as they turn syrup of violets green. In the urine of domestic fowls, Fourcroy and Vauquelin found lithic acid. Urine has been employed for making phos- phorus, volatile alkali, and sal ammoniac; moulds to the produce of nitre beds ; and it is very useful in a putrid state for scouring woollens. URINE (BLUE). In certain morbid conditions of the body a blue urine has been voided which M. Braconnot has given an ac- count of in the 29th volume of the Annales de. Chimie et Physique, p. 252. It is a peculiar substance which gives the colour. He pro- poses to call it cyanourine. It resembles the organic salifiable bases in combining with acids, in refusing to dissolve in alkalis, and in the large proportion of carbon which it con- tains. URINARY CALCULI. See CALCULI (URINARY). VAPOUR. The general principles of the formation of vapour have been explained under the article CALORIC, changes of state. Some observations have been added under EVAPORATION and GAS. Fig. 15. plate XIV. represents one form of the apparatus, which I employed for deter- mining the elastic force of vapours at different temperatures. L, 1, are the initial levels of the mercurial columns in the two legs of the syphon barometer. I, is the fine wire of pla- tina, to which the quicksilver was made a tangent, at every measurement, by pouring mercury into the open leg, till its vertical pressure equipoised the elastic force of the vapour above /. The column added over L, measured directly that elastic force. See the Tables in the Appendix. VAREC. The French name for kelp, or incinerated sea-weed. VARNISH. Lac-varnishes or lacquers consist of different resins in a state of solution, of which the most common are mastich, sand- arach, lac, benzoin, copal, amber, and asphal- tum. The menstrua are either expressed or essential oils, as also alcohol. For a lac- var- nish of the first kind, the common painter's varnish is to be united by gently boiling it with some more mastich or colophony, and then diluted again with a little more oil of turpentine. The latter addition promotes both the glossy appearance and drying of the var- nish. Of this sort is the amber-varnish. To make this varnish, half a pound of amber is kept over a gentle fire in a covered iron pot, in the lid of which there is a small hole, till it is observed to become soft, and to be melted together into one mass. As soon as this is perceived, the vessel is taken from off the fire, and suffered to cool a little ; when a pound of good painter's varnish is added to it, and the whole suffered to boil up again over the fire, keeping it continually stirring. After this, it is again removed from the fire ; and when it is become somewhat cool, a pound of oil of tur- pentine is to be gradually mixed with it. Should the varnish, when it is cool, happen to be yet too thick, it may be attenuated with more oil of turpentine. This varnish has always a dark brown colour, because the amber is previously half-burned in this operation ; but if it be required of a bright colour, amber powder must be dissolved in transparent pain- ter's varnish, in Papin's machine, by a gentle fire. As an instance of the second sort of lac- varnishes with ethereal oils alone, may be adduced the varnish made with oil of turpen- tine. For making this, mastich alone is dis- solved in oil of turpentine by a very gentle digesting heat, in close glass vessels. This is the varnish used for the modern transparencies employed as window-blinds, fire-screens, and for other purposes. These are commonly prints, coloured on both sides, and afterwards coated with this varnish on those parts that are intended to be transparent. Sometimes fine thin calico, or Irish linen, is used for this purpose ; but it requires to be primed with a solution of isinglass, before the colour is laid on. Copal may be dissolved in genuine Chio turpentine, according to Mr. Sheldrake, by VAR 783 VEG adding it in powder to the turpentine pre- viously melted, and stirring till the whole is fused. Oil of turpentine may then be added to dilute it sufficiently. Or the copal in pow- der may be put into a long-necked matrass with twelve parts of oil of turpentine, and di- gested several days on a sand-heat, frequently shaking it. This may be diluted with one. fourth or one-fifth of alcohol. Metallic ves- sels or instruments, covered with two or three coats of this, and dried in an oven each time, may be washed with boiling water, or even ex- posed to a still greater heat, without injury to the varnish. A varnish of the consistence of thin turpen- tine is obtained for aerostatic machines, by the digestion of one part of elastic gum, or caout- chouc, cut into small pieces, in thirty-two parts of rectified oil of turpentine. Previously to its being used, however, it must be passed through a linen cloth, in order that the un- dissolved parts may be left behind. The third sort of lac-varnishes consists in the spirit-varnish. The most solid resins yield the most durable varnishes ; but a varnish must never be expected to be harder than the resin naturally is of which it is made. Hence, it is the height of absurdity to suppose that there are any incombustible var- nishes, since there is no such thing as an in- combustible resin. But the most solid resins by themselves produce brittle varnishes; there- fore, something of a softer substance must al- ways be mixed with them, whereby this brit- tleness is diminished. For this purpose, gum- elemi, turpentine, or balsam of copaiva are employed in proper proportions. For the so- lution of these bodies the strongest alcohol ought to be used, which may very properly indeed be distilled over alkali, but must not have stood upon alkali. The utmost simpli- city in composition, with respect to the num- ber of the ingredients in a formula, is the re- sult of the greatest skill in the art ; hence it is no wonder, that the greatest part of the formu- las and recipes that we meet with are com- posed without any principle at all. In conformity^ to these rules, a fine colour- less varnish may be obtained, by dissolving eight ounces of gum - sandarach and two ounces of Venice turpentine in thirty -two ounces of alcohol by a gentle heat. Five ounces of shell-lac and one of turpentine, dis- solved in thirty-two ounces of alcohol by a very gentle heat, give a harder varnish, but of a reddish cast. To these the solution of copal is undoubtedly preferable in many re- spects. This is effected by triturating an ounce of powder of gum-copal, which has been well dried by a gentle heat, with a drachm of camphor, and, while these are mixing together, adding by degrees four ounces of the strongest alcohol, without any digestion. Between this and the gold varnish there is only this difference, that some substances that communicate a yellow tinge are to be added to the latter. The most ancient description of two sorts of it, one of which was prepared with oil, and the other with alcohol, is to be found in Alexius Pedemontanus Dei Secreti, Lucca, of which the first edition was published in the year 1557. But it is better prepared, and more durable, when made after the fol- lowing prescription: Take two ounces of shell-lac, of amotto and turmeric of each one ounce, and thirty grains of fine dragon's-blood, and make an extract with twenty ounces of alcohol in a gentle heat. Oil-varnishes are commonly mixed imme- diately with the colours, but lac or lacquer varnishes are laid on by themselves upon a burnished coloured ground : when they are in- tended to be laid upon naked wood, a ground should be first given them of strong size, either alone, or with some earthy colour mixed up with it by levigation. The gold lacquer is simply rubbed over brass, tin, or silver, to give them a gold colour. Before a resin is dissolved in a fixed oil, it is necessary to render the oil drying. For this purpose the oil is boiled with metallic oxides, in which operation the mucilage of the oil combines with the metal, while the oil itself unites with the oxygen of the oxide. To accelerate the drying of this varnish, it is necessary to add oil of turpentine. The essential varnishes consist of a solu- tion of resin in oil of turpentine. The var- nish being applied, the essential oil flies off, and leaves the resin. This is used only for paintings. When resins are dissolved in alcohol, the varnish dries very speedily, and is subject to crack ; but this fault is corrected by adding a small quantity of turpentine to the mixture, which renders it brighter, and less brittle when dry. The coloured resins or gums, such as gam- boge, dragon's-blood, &c. are used to colour varnishes. To give lustre to the varnish after it is laid on, it is rubbed with pounded pumice-stone and water; which being dried with a cloth, the work is afterward rubbed with an oiled rag and tripoli. The surface is last of all cleaned with soft linen cloths, cleared of all greasiness with powder of starch, and rubbed bright with the palm of the hand. VAUQUELINITE. Chromate of lead and copper, a mineral which occurs in small crystals on quartz, accompanying the chromate of lead in Siberia. VEGETABLE KINGDOM. In the mineral kingdom, little of chemical operation takes place, wherein the peculiar locality or disposition of the principles which act upon each other appears to have any considerable effect. The principles, for the most part simple, act upon each other by virtue of their VEG 784 VEG respective attractions : if heat be developed, it is for the most part speedily conducted away ; if elastic products be extricated, they in general make their escape ; in a word, we seldom perceive in the operations in the mi- neral kingdom any arrangement, which at all resembles the artificial dispositions of the chemist. But in the animal and vegetable kingdoms it is far otherwise. In the former of these, bodies are regularly changed by mechanical division, by digestion, and the application of peculiar solvents, in a temperature exceeding that of the atmosphere ; and the whole of the effects are assisted, modified, and kept up by an apparatus for admitting the air of the at- mosphere. The subjects of the vegetable kingdom possess undoubtedly a structure less elaborate. They exhibit much less of those energies which are said to be spontaneous. The form of their vessels is much simpler, and, as far as we can perceive, their action is obedient to the changes of the atmosphere in quality and moisture, the mechanical action of winds, the temperature of the weather, and the influence of light. In these organized beings, the chemist discovers principles of a more compounded nature, than any which can be obtained from the mineral kingdom. These do not previously exist in the earth, and must therefore be results of vegetable life. The most obvious difference between vege- tables and animals is, that the latter are in general capable of conveying themselves from place to place ; whereas vegetables, being fixed in the same place, absorb, by means of their roots and leaves, such support as is within their reach. This appears on the whole to consist of air and water. The greatest part of the support of animals are the products al- ready elaborated in the vegetable kingdom. The products of these two kingdoms in the hands of the chemist are remarkably different, though perhaps not exclusively so. One of most distinctive characters seems to be the presence of nitrogen or azotic gas, which may be extricated from animal substances by the application of nitric acid, and enters into the composition of the ammonia afforded by de- structive distillation. It was long supposed that ammonia was exclusively the product of the animal kingdom, but it is now well known, that certain plants likewise afford it. When it is considered, that by far the greater part of every organized substance is capable of assuming the elastic form, and being volatilized by heat ; that the products are during life brought into combination by slow and long-continued processes, and are kept separate from each other in the vessels of the plant or animal ; that these combina- tions are liable to be altered by the destruc- tion of those vessels, as well as by every nota- ble change of temperature it will not ap- pear surprising, that the chemical analysis of plants should be in an imperfect state. See ANALYSIS. In the structure of vegetables we observe the external covering or bark, the ligneous or woody matter, the vessels or tubes, and certain glandular or knotty parts. The comparative anatomy, and immediate uses of these parts, form an object of interesting research, but less immediately within the province of a chemical work. The nutrition or support of plants appears to require water, earth, light, and air. There are various experiments which have been in- stituted to show, that water is the only ali- ment which the root draws from the earth. Van Helmont planted a willow, weighing fifty pounds, in a certain quantity of earth covered with sheet lead ; he watered it for five years with distilled water, and at the end of that time the tree weighed one hundred and sixty-nine pounds three ounces, and the earth in which it had vegetated was found to have suffered a loss of no more than three ounces. Boyle repeated the same experiment upon a plant, which at the end of two years weighed fourteen pounds more, without the earth in which it had vegetated having lost any per- ceptible portion of its weight. Messrs. Duhamel and^ Bonnet supported plants with moss, and fed them with mere water : they observed, that the vegetation was of the most vigorous kind ; and the naturalist of Geneva observes, that the flowers were more odoriferous, and the fruit of a higher flavour. Care was taken to change the sup- ports before they could suffer any alteration. Mr. Tillet has likewise raised plants, more especially of the gramineous kind, in a simi- lar manner, with this difference only, that his supports were pounded glass, or quartz in powder. Hales has observed, that a plant, which weighed three pounds, gained three ounces after a heavy dew. Do we not every day observe hyacinths and other bulbous plants, as well as gramineous plants, raised in saucers or bottles containing mere water ? And Braconnot has lately found mustard- seed to germinate, grow, and produce plants, that came to maturity, flowered, and ripened their seed, in litharge, flowers of sulphur, and very small unglazed shot. The last appeared least favourable to the growth of the plants, apparently because their roots could not pene- trate between it so easily. All plants do not demand the same quan- tity of water ; and nature has varied the organs of the several individuals conformably to the necessity of their being supplied with this food. Plants which transpire little, such as the mosses and the lichens, have no need of a considerable quantity of this fluid ; and, ac- cordingly, they are fixed upon dry rocks, and have scarcely any roots; but plants which require a larger quantity, have roots which YEG 785 VEG extend to a great distance, and absorb humi- dity throughout their whole surface. The leaves of plants have likewise the pro. perty of absorbing water, and of extracting from the atmosphere the same principles which the root draws from the earth. But plants which live in the water, and as it were swim in the element which serves them for food, have no need of roots ; they receive the fluid at all their pores ; and we accordingly find, that the fucus, the ulva, &c. have no roots whatever. The dung which is mixed with earths, and decomposed, not only affords the alimentary principles we have spoken of, but likewise favours the growth of the plant by that con- stant and steady heat which its ulterior de- composition produces. Thus it is that Fabroni affirms his having observed the development of leaves and flowers in that part of a tree only which was in the vicinity of a heap of dung. From the preceding circumstances, it ap- pears, that the influence of the earth in vege- tation is almost totally confined to the con- veyance of water, and probably the elastic products from putrefying substances, to the plant. Vegetables cannot live without air. From the experiments of Priestley, Ingenhousz, and Sennebier, it is ascertained, that plants absorb the azotic part of the atmosphere ; and this principle appears to be the cause of the fertility which arises from the use of putrefying mat- ters in the form of manure. The carbonic acid is likewise absorbed by vegetables, when its quantity is small. If in large quantity, it is fatal to them. Chaptal has observed, that carbonic acid predominates in the fungus, and other subter- raneous plants. But by causing these vegeta- bles, together with the body upon which they were fixed, to pass, by imperceptible grada- tions, from an almost absolute darkness, into the light, the acid very nearly disappeared ; the vegetable fibres being proportionally increased, at the same time that the resin and colouring principles were developed, which he ascribes to the oxygen of the same acid. Sennebier has observed, that the plants which he watered with water impregnated with carbonic acid transpired an extraordinary quantity of oxygen, which likewise indicates a decomposition of the acid. Light is almost absolutely necessary to plants. In the dark they grow pale, languish, and die. The tendency of plants toward the light is remarkably seen in such vegetation as is effected in a chamber or place where the light is admitted on one side ; for the plant never fails to grow in that direction. Whether the matter of light be condensed into the sub- stance of plants, or whether it act merely as a stimulus or agent, without which the other requisite chemical processes cannot be effected, is uncertain. It is ascertained, that the processes in plants serve, like those in animals, to produce a more equable temperature, which is for the most part above that of the atmosphere. Dr. Hunter, quoted by Chaptal, observed, by keeping a thermometer plunged in a hole made in a sound tree, that it constantly indicated a tem- perature several degrees above that of the atmosphere, when it was below the fifty- sixth division of Fahrenheit ; whereas the vegetable heat, in hotter weather, was always several degrees below that of the atmosphere. The same philosopher has likewise observed, that the sap which, out of the tree, would freeze at 32, did riot freeze in the tree unless the cold were augmented 15 more. The vegetable heat may increase or di- minish by several causes, of the nature of disease ; and it may even become perceptible to the touch in very cold weather, according to Buffon. The principles of which vegetables are com- posed, if we pursue their analysis as far as our means have hitherto allowed, are chiefly carbon, hydrogen, and oxygen. Nitrogen is a constituent principle of several, but for the most part in small quantity. Potash, soda, lime, magnesia, silex, alumina, sulphur, phosphorus, iron, manganese, and muriatic acid, have likewise been reckoned in the num- ber ; but some of these occur only occasionally, and chiefly in very small quantities ; and are scarcely more entitled to be considered as be- longing to them than gold, or some other sub- stances, that have been occasionally procured from their decomposition. The following are the principal products of vegetation : 1. Sugar. Crystallizes. Soluble in water and alcohol. Taste sweet. Soluble in nitrie acid, and yields oxalic acid. 2. Sarcocol. Does not crystallize. Soluble in water and alcohol. Taste bitter sweet. Solu- ble in nitric acid, and yields oxalic acid. 3. Asparagin. Crystallizes. Taste cooling and nauseous. Soluble in hot water. Inso- luble in alcohol. Soluble in nitric acid, and converted into bitter principle and artificial tannin. 4. Gum. Does not crystallize. Taste in- sipid. Soluble in water, and forms mucilage. Insoluble in alcohol. Precipitated by silicated potash. Soluble in nitric acid, and forms mucous and oxalic acids. $ Ulmin. Does not crystallize. Taste insipid. Soluble in water, and does not form mucilage. Precipitated by nitric and oxymu- riatic acids in the state of resin. Insoluble in alcohol. 6. Inulin. A white powder. Insoluble in cold water. Soluble in boiling water; but precipitates unaltered after the solution cools., 3 z VEG 786 VEG Insoluble in alcohol. Soluble in nitric acid, and yields oxalic acid. 7. Starch. A white powder. Taste insipid. Insoluble in cold water. Soluble in hot water ; opaque and glutinous. Precipitated by an infusion of nutgalls ; precipitate redisssolved by a heat of 120. Insoluble in alcohol. Soluble in dilute nitric acid, and precipitated by alcohol. With nitric acid yields oxalic acid and a waxy matter. 8. Indigo. A blue powder. Taste insipid. Insoluble in water, alcohol, ether- Soluble in sulphuric acid. Soluble in nitric acid, and converted into bitter principle and artificial tannin. 9. Gluten. Forms a ductile elastic mass with water. Partially soluble in water ; pre- cipitated by infusion of nutgalls and oxygen- ized muriatic acid. Soluble in acetic acid and muriatic acid. Insoluble in alcohol. By fer- mentation becomes viscid and adhesive, and then assumes the properties of cheese. Soluble in nitric acid, and yields oxalic acid. 10. Albumen. Soluble in cold water. Coagulated by heat, and becomes insoluble. Insoluble in alcohol. Precipitated by infusion of nutgalls. Soluble in nitric acid. Soon putrefies. 11. Fibrin. Tasteless. Insoluble in water and alcohol. Soluble in diluted alkalis, and in nitric acid. Soon putrefies. 12. Gelatin. Insipid. Soluble in water. Does not coagulate when heated. Precipitated by infusion of galls. 13. Sitter principle. Colour yellow or brown. Taste bitter. Equally soluble in water and alcohol. Soluble in nitric acid. Precipitated by nitrate of silver. 14. Extractive. Soluble in water and al- cohol. Insoluble in ether. Precipitated by oxygenized muriatic acid, muriate of tin, and muriate of alumina ; but not by gelatin. Dyes fawn colour. 15. Tannin. Taste astringent. Soluble in water and in alcohol of 0-810. Precipitated by gelatin, muriate of alumina, and muriate of tin. 16. Fixed oils. No smell. Insoluble in water and alcohol. Forms soaps with alkalis. Coagulated by earthy and metallic salts. 17. Wax. Insoluble in water. Soluble in alcohol, ether, and oils. Forms soap with alkalis. Fusible. 18. Volatile oil. Strong smell. Insoluble in water. Soluble in alcohol. Liquid. Vo- latile. Oily. By nitric acid inflamed, and converted into resinous substances. 19. Camphor. Strong odour. Crystal- lizes. Very little soluble in water. Soluble in alcohol, oils, acids. Insoluble in alkalis. Burns with a clear flame, and volatilizes be- fore melting. 20. Birdlime. Viscid. Taste insipid. Insoluble in water. Partially soluble in alcohol. Very soluble in ether. Solution green. 21. Resins. Solid. Melt when heated. Insoluble in water. Soluble in alcohol, ether, and alkalis. Soluble in acetic acid. By nitric acid converted into artificial tannin. 22. Giiaiacum. Possesses the characters of resins ; but dissolves in nitric acid, and yields oxalic acid and no tannin. 23. Balsams. Possess the characters of the resins, but have a strong smell ; when heated, benzoic acid sublimes. It sublimes also when they are dissolved in sulphuric acid. By nitric acid converted into artificial tannin. 24. Caoutchouc. Very elastic. Insoluble in water and alcohol. When steeped in ether, reduced to a pulp, which adheres to every thing. Fusible, and remains liquid. Very combustible. 25. Gum resins- Form milky solutions with water, transparent with alcohol. So- luble in alkalis. With nitric acid converted into tannin. Strong smell. Brittle, opaque, infusible. 26. Cotton. Composed of fibres. Tasteless. Very combustible. Insoluble in water, alco- hol, and ether. Soluble in alkalis. Yields oxalic acid to nitric acid. 27. Suler. Burns bright, and swells. Con- verted by nitric acid into suberic acid and wax. Partially soluble in water and alcohol. 28. Wood. Composed of fibres. Tasteless. Insoluble in water and alcohol. Soluble in weak alkaline lixivium. Precipitated by acids. Leaves much charcoal when distilled in a red heat Soluble in nitric acid, and yields oxalic acid. To the preceding we may add, emetin, fungin, hemalin, nicotin, pollenin; the new vegetable alkalis, aconita, atropia, brucia, cicuta, datura, delphia, hyosciama, morphia, picrotoxia, strychnia, veratria ; and the various vegetable acids enumerated under the general article ACID. MM. Dumas and Pelletier published a long and able memoir on the elementary composi- tion and certain characteristic properties of the organic salifiable bases (vegeto-alkalis), in the 24th volume of the Annaks de Chim. et Phys. p. 163, which was read to the Aca- demy of Sciences, 5th May, 1823. The fol- lowing is a tabular view of the relations of carbon and azote in these alkaline bodies. Carbonic acid. Azote. Quinia, 100 5-1 Cinchonia, 100 5-0 Strychnia, 100 4-9 Narcotine, 100 4-5 Brucina, 120 5-0 Morphia, 100 3-2 Veratria, 100 3-2 Emetin, 100 3-1 Cafeine, 100 20-0 M. Robiquet has on more than one occasion VEG 787 VER stated his doubts of the pre-existence of organic alkalis in vegetables; and he conjectures that they were produced by the re-action of alkaline substances on certain immediate products of plants, and more particularly on what may be named the resinous principle or resinoide. The ammonia existing in many vegetables may be supposed to be an active agent in such a transformation. Annales de Chimic, xxxi. 67- VEGETATION (SALINE). M.Chap. tal has given us a good memoir on this sub- ject, in the Journal dc Physique for October 1788, entitled Observations on the Influence of the Air and Light upon the Vegetation of Salts. In the operations in the large way, of his manufactory of medical and chemical products, he often observed that salts, particularly the metallic, vegetated on the side most exposed to the light ; and the frequency of the effect induced him to make some direct experiments on the subject. For this purpose he took several capsules of glass, and covered the half of each, as well above as below, with black silk. At the same time, he prepared solutions of almost all the earthy, alkaline, or metallic compound salts in distilled water, at the tem- perature of the atmosphere. These capsules were placed on tables in a well closed cham- ber, which had no chimney, and of which the doors and windows were carefully stopped up, in order that the evaporation might not be hastened by any agitation of the air. Reflected light, by which I understand the light from the clouds, was admitted through a small aper- ture in one of the window-shutters. By this management, as well as the disposition of the capsules, one-half of each of their respective cavities received light from the aperture, and the other was almost perfectly in darkness. The solutions were then carefully poured into the capsules by means of a funnel resting on the middle of the bottom, so that the border of the fluid was neat and uniform, without any irregularity or drop of the fluid falling on the bare surface of the glass. Upwards of two hundred experiments were made, with variations of the principal trials, so as to leave no doubt with regard to the constancy of the results. The most remark- able fact is, that the vegetation took place on those surfaces only which were illuminated. This phenomenon was so striking in most of the solutions, that in the space of a few days, and frequently even within one single day, the salt was elevated several lines above the liquor upon the enlightened surface, while there did not appear the smallest crust or edge on the dark part. Nothing could be more interesting than to observe this vegetation, projecting frequently more than an inch, and marking the line of distinction between the illuminated and dark parts of the vessel. The sulphates of iron, of zinc, and other metals, more especially presented this appearance. It was generally observed, that the vegetation was strongest toward the most enlightened part. This phenomenon may be rendered still more interesting, by directing the vegetation at pleasure toward the different parts of the vessel. For this purpose, nothing more is required than to cover the several parts in succession. For the vegetation always takes place in the enlightened parts, and quickly ceases in that which is covered. When the same solution has stood for seve- ral days, the insensible evaporation gradually depresses its surface, and a crust or edge of salt is left in the obscure part. But the salt never rises, or at least very imperfectly, above the liquor, and cannot be compared with the true vegetation. When salts are suffered to vegetate in this manner, the spontaneous evaporation of the fluid affords very few crystals. All the saline matter extends itself on the sides of the vessel. VEINS. The ores of metds are frequently found to fill certain clefts in mountains. These masses, when they run out in length, are called veins. Inconsiderable veins, which diverge from the principal, are called slips ; and such masses of ore as are of considerable magni- tude, but no great length, are called bellies, or stock- works. VERATRIA. A new vegetable alkali, discovered lately by MM. Pelletier and Ca- ventou, in the veratrum sabatllla or cevadilla, the veratrum album or white hellebore, and the colchicum autumnale or meadow saffron. The seeds of cevadilla, after being freed from an unctuous and acrid matter by ether, were digested in boiling alcohol. As this infusion cooled, a little wax was deposited; and the liquid being evaporated to an extract, redissolved in water, and again concentrated by evaporation, parted with its colouring matter. Acetate of lead was now poured into the solution, and an abundant yellow precipitate fell, leaving the fluid nearly colour- less. The excess of lead was thrown down by sulphuretted hydrogen, and the filtered liquor being concentrated by evaporation, was treated with magnesia, and again filtered. The precipitate, boiled in alcohol, gave a solution, which, on evaporation, left a pulverulent mat- ter, extremely bitter, and with decidedly alka- line characters. It was at first yellow, but by solution in alcohol, and precipitation by water, was obtained in a fine white powder. * The precipitate by the acetate of lead gave, on examination, gallic acid ; and hence it is concluded that the new alkali existed in the seed as a gallate. Veratria was found in the other plants above mentioned. It is white, pulverulent, has no odour, but excites violent sneezing. It is very acrid, but not bitter. It produced violent vomiting in very small doses, and, according 3 E 2 VER 788 VOL to some experiments,- a few grains may cause death. It is very little soluble in cold water. Boiling water dissolves about -j-yjpj part, and becomes acrid to the taste. It is very soluble in alcohol, and rather less soluble in ether. It fuses at 122 F., and then appears like wax. On cooling, it becomes an amber-coloured translucent mass. Heated more highly, it swells, decomposes, and burns. Decomposed by oxide of copper, it gave no trace of azote. It acts on test papers like an alkali, and forms salts uncrystallizable by evaporation. The salts appear like a gum. The supersulphate only seems to present crystals. Strong solu- tions of these salts are partially decomposed by water. Veratria falls down, and the solution becomes acid. The bisulphate appears to con- sist of, Veratria, 93-723 100 Sulphuric acid, 6-227 6-6441 The muriate is composed of, Veratria, 95-8606 100 Muriatic acid, 4-1394 4-3181 Iodine and chlorine produce with veratria an iodate, hydriodate, chloride, and muriate. VERDIGRIS. A crude acetate of copper. Mr. Phillips has lately published the fol- lowing analyses of verdigris. French. Enplish. Acetic acid, 29-3 29-62 Peroxide of copper, 43-5 44-25 Water, 25-2 25-51 Impurity, 2-0 0-62 100-0 100-00 Phillips' Annals, No. 21. VERDITER is a blue pigment, obtained by adding chalk or whiting to the solution of copper in aquafortis. Dr. Merret says, that it is prepared in the following manner: a quantity of whiting ns put into a tub, and upon this the solution of the copper is poured. The mixture is to be stirred every day for some hours together, till the liquor loses its colour. The liquor is then to be poured off, and more solution of copper is to be added. This is to be repeated till the whiting has acquired the proper colour. Then it is to be spread on large pieces of chalk, and dried in the sun. It appears from M. Pelletier's analysis, that 100 grains of the very best verditer con- tain, of carbonic acid 30, of water 3, of pure lime 7, of oxygen 9|, and of pure copper 50. Th^ author remarks, that the verditers of inferior quality contain more chalk and less copper, VERJUICE. A kind of harsh, austere vinegar, made of the expressed juice of the wild apple, or crab. The French give this name to unripe grapes, and to the sour liquor obtained from them. VERMILION. The red sulphuret of mer- cury, or cinnabar. VESSELS (CHEMICAL). See APPA- RATUS. VESUVIAN. Idocrase of Hatty ; a sub- species of pyramidal garnet. Colours green and brown. Massive, disseminated, and crystallizjd. Primitive form, a pyramid of 129 30 y and 74 12'. The following secon- dary forms occur ; a rectangular four-sided prism variously acuminated, bevelled or trun- cated. The lateral planes of the prism are longitudinally streaked. Glistening vitreo- resinous. Cleavage imperfect, but in the di- rection of the diagnonals. Fracture small grained uneven. Translucent. Refracts dou- ble. Scratches felspar. Brittle. Sp- gr. 3.3 to 3-4. It becomes electrical by fricdon. Be- fore the blowpipe it melts without addition into a yellowish, and faintly translucent glass. Its constituents are, silica 35-5, lime 33, alumina 22-25, oxide of iron 7*5, oxide of manganese 0-25, loss 1.5. Klaproth. It occurs in considerable abundance, in unaltered ejected rocks, in the vicinity of Vesuvius. The rare blue variety is foJhd at Sonland, in Tel- lemark, in Norway. At Naples it is cut into ring-stones. " VINEGAR. See FERMENTATION (ACETOUS ; and also ACID ( ACETIC), where the mode of making it is given. VINEGAR FROM WOOD. M. Stolze, apothecary at Halle, has discovered a method of purifying vinegar from wood, by treating it with sulphuric acid, manganese, and common salt, and afterwards distilling it over. VINEGAR OF SATURN. Solution of acetate of lead. VINEGAR (RADICAL). Acetic acid. VIOLINE. A supposed new vegeto- alkali, thought to exist in the viola odorata. It has properties analogous to emetine, and may be extracted from the root, leaves, flow- ers, and seeds of the plant. Journ. de Pharm. Jan. 1824. VITAL AIR. See OXYGEN. VITRIFICATION. See GLASS; also SILICA. VITRIOL, blue, green, red, white. See ORES of COPPER, IRON, COBALT, ZINC. VITRIOLIC ACID. See ACID (SUL- PHURIC). V1VIANITE. Phosphate of iron. VOLATILE ALKALI. See AMJIONIA. VOLATILITY. The property of bodies by which they are disposed to assume the vaporous or elastic state, and quit the vessels in which they are placed. VOLCANOES. The combustion of those enormous masses of bitumen which are de- posited in the bowels of the earth produces vol- canoes. They owe their origin more espe- cially to the strata of pyritous coal. The decomposition or action of water upon the pyrites determines the heat, and the produc- tion of a great quantity of hydrogen, which exerts itself against the surrounding obstacles, VOL 789 VOL and at length breaks them. This effect appears to be the chief cause of earthquakes ; but when the concourse of air facilitates the com- bustion of the bitumen and the hydrogen, the flame is seen to issue out of the chimneys or vents which are made ; and this occasions the fire of volcanoes. There are many volcanoes still in an active state on our globe, independent of those of Italy, which are the most known. The Abbe Chappe has described three burning in Sibe- ria. Anderson and Von Troil have described those of Iceland; Asia and Africa contain several ; and we find the remains of these fires or volcanic products in all parts of the globe. Naturalists inform us that all the southern islands have been volcanized ; and they are seen daily to be formed by the action of these subterraneous fires. The black colour of the stones, their spongy texture, the other pro- ducts of fire, and the identity of these sub- stances with those of the volcanoes at present burning, are all in favour of the opinion that their origin was the same. When the decomposition of the pyrites is advanced, and the vapours and elastic fluids can no longer be contained in the bowels of the earth, the ground is shaken, and exhibits the phenomenon of earthquakes. Mephitic vapours are multiplied on the surface of the ground, and dreadful hollow noises are heard. In Iceland the rivers and springs are swal- lowed up ; a thick smoke, mixed with sparks and lightning, is then disengaged from the crater; and naturalists have observed, when the smoke of Vesuvius takes the form of a pine, the eruption is near at hand. To these preludes, which show the internal agitation to be great, and that obstacles oppose the issue of the volcanic matters, succeeds an eruption of stones and other products, which the lava drives before it ; and, lastly, appears a river of lava, which flows out, and spreads itself down the side of the mountain. At this period the calm is restored in the bowels of the earth, and the eruption continues without earthquakes. The violent efforts of the in- cluded matter sometimes cause the sides of the mountain to open ; and this is the cause which has successively formed the smaller mountains that surround volcanoes. Montenuevo, which is a hundred and eighty feet high, and three thousand in breadth, was formed in a night. This crisis is sometimes succeeded by an eruption of ashes, which darkens the air. These ashes are the last result of the altera- tion of the coals; and the matter which is first thrown out is that which the heat has half vitrified. In the year 1767 the ashes of Vesuvius were carried twenty leagues out to sea, and the streets of Naples were covered with them. The report of Dion, concerning the eruption of Vesuvius in the reign of Titus, wherein the ashes were carried into Africa, Egypt, and Syria, seems to be fabulous. M. de Saussure observes, that the soil of Rome is of this character, and that the famous cata- combs are all made in the volcanic ashes. It must be admitted, however, that the force with which all these products are thrown is astonishing. In the year 1769, a stone, twelve feet high and four in circumference, was thrown to the distance of a quarter of a mile from the crater : and in the year 1771 Sir William Hamilton observed stones of an enormous size, which employed eleven seconds in falling. This indicates an elevation of near two thousand feet. The eruption of volcanoes is frequently aqueous ; the water which is confined, and favours the decomposition of the pyrites, is sometimes strongly thrown out. Sea salt is found among the ejected matter, and likewise sal ammoniac. In the year 1630, a torrent of boiling water, mixed with lava, destroyed Portici and Torre del Greco. Sir W. Hamil- ton saw boiling water ejected. The springs of boiling water in Iceland, and all the hot springs which abound at the surface of the globe, owe their heat only to the decomposition of py- rites. Some eruptions are of a muddy substance ; and these form the tuffa and the pouzzolano. The eruption which buried Herculaneum is of this kind. Sir W. Hamilton found an antique head, the impression of which was well enough preserved to answer the purpose of a mould. Herculaneum at the least depth is seventy feet under the surface of the ground, and in many places one hundred and twenty. The pouzzolano is of various colours. It is usually reddish, sometimes gray, white, or green : it frequently consists of pumice-stone in powder; but sometimes it is formed of oxided clay. One hundred parts of red pouz- zolano afforded Berginann silex 55, alumina 20, lime 5, iron 20. When the lava is once thrown out of the crater, it rolls in large rivers down the side of the mountain to a certain distance, which forms the currents of lava, the volcanic causeways, &c. The surface of the lava cools, and forms a solid crust, under which the liquid lava flows. After the eruption, this crust some- times remains, and forms hollow galleries, which Messrs. Hamilton and Ferber have vi- sited : it is in these hollow places that the sal ammoniac, the muriate of soda, and other substances sublime. A lava may be turned out of its course by opposing banks or dykes against it: this was done in 1669 to save Catania; and Sir William Hamilton proposed it to the king of Naples to preserve Portici. The currents of lava sometimes remain several years in cooling. Sir William Hamil- ton observed, in 1769, that the lava which flowed in 1766 was still smoking in some places. Lava is sometimes swelled up and porous. The lightest is called pumice-stone. WAC 790 WAC The substances thrown out by volcanoes are not altered by fire. They eject native substances, such as quartz, crystals of ame- thyst, agate, gypsum, amianthus, felspar, mica, shells, schorl, &c. The fire of volcanoes is seldom strong enough to vitrify the matters it throws out. We know only of the yellowish capillary and flexible glass thrown out by the volcanoes of the island of Bourbon, on the 14th of May 1766, (M. Commerson), and the lapis galli- naceus ejected by Hecla. Mr. Egolfrigouson, who is employed by the observatory at Copen- hagen, has settled in Iceland, where he uses a mirror of a telescope which he has made out of the black agate of Iceland. The slow operation of time decomposes lavas, and their remains are very proper for vegetation. The fertile island of Sicily has been every-where volcanized. Chaptal ob- served several ancient volcanoes at present cultivated ; and the line which separates the other earths from the volcanic eatth consti- tutes the limit of vegetation. The ground over the ruins of Pompeii is highly culti- vated. Sir William Hamilton considers sub- terranean fires as the great vehicle used by nature to extract virgin earth out of* the bowels of the globe, and repair the exhausted surface. The decomposition of lava is very slow. Strata of vegetable earth, and pure lava, are occasionally found applied one over the other; which denote eruptions made at distances of time very remote from each other, since in some instances it appears to have required nearly two thousand years before lava was fit to receive the plough. In this respect, how- ever, lavas differ very widely, so that our reasoning from them must at best be very vague. An argument has been drawn from this phenomenon to prove the antiquity of the globe; but the silence of the most ancient authors concerning the volcanoes of the king- dom of France, of which we find such fre- quent traces, indicates that these volcanoes have been extinguished from time immemo- rial ; a circumstance Avhich carries their exist- ence to a very distant period. Beside this, several thousand years of connected observa- tions have not afforded any remarkable change in Vesuvius or Attna. : nevertheless these enormous mountains are all volcanized, and consequently formed of strata applied one. upon the other. The prodigy becomes much more striking, when we observe, that all the surrounding country, to very great distances, has been thrown out of the bowels of the earth. The height of Vesuvius above the level of the sea is three thousand six hundred and fifty- nine feet ; its circumference thirty -four thou- sand four hundred and forty -four. The height of ./Etna is ten thousand and thirty-six feet ; and its circumference one hundred and eighty thousand. The various volcanic products are applica- ble to several uses. 1. Pouzzolano is of admirable use for building in the water : when mixed with lime it speedily fixes itself; and water does not soften it, for it becomes continually harder and harder. Chaptal has proved that oxided ochres afford the same advantage for this purpose : they are made into balls, and baked in a potter's furnace in the usual manner. The experiments made at Sette, by the commissary of the province, prove, that they may be substituted with the great- est advantage instead of the pouzzolano of Italy. 2. Lava is likewise susceptible of vitrifica- tion ; and in this state it may be blown into opaque bottles of the greatest lightness, which Chaptal says he has done at Erepian and at Alais. The very hard lava, mixed in equal parts with wocd-ashes and soda, produced, he says, an excellent green glass. The bot- tles made of it were only half the weight of common bottles, and much stronger, as was proved by Chaptal's experiments, and those which M. Joly de Fleury ordered to be made under his administration. 3. Pumice-stone likewise has its uses ; it is more especially used to polish most bodies which are somewhat hard. It is employed in the mass or in powder, according to the in- tended purpose. Sometimes, after levigation, it is mixed with water to render it softer. VOLCAN1TE. Augite. VULPINITE. Colour greyish-white. Massive. Splendent. Fracture foliated. Frag- ments rhomboidal. In distinct granular con- cretions. Translucent on the edges. Soft. Brittle. Sp. gr. 2-878. It melts easily be- fore the blowpipe into a white opaque enamel. Its constituents are, sulphate of lime 82, silica 8. It occurs along with granular foliated limestone at Vulpino, in Italy. W WACKE. A mineral substance interme- diate between clay and basalt. It is some- times simple ; but when it inclines to basalt, it contains hornblende and mica. It is some- times spotted, and these spots are unformed crystals of hornblende, resembling the unform- ed crystals of felspar in certain varieties of porphyry. It never contains augite or olivine. When it approaches to an amygdaloid, it is vesicular. Its colour is greenish-grey. Mas- WAT 791 WAT save and vesicular. Dull. Opaque. Streak shining. Soft. Easily frangible. Sp, gr. 2-55 to 2-9. Fuses like basalt It seldom contains petrifactions. It occurs sometimes in beds and veins, and these veins contain very small portions of ores of different kinds, as bismuth, silver-glance, and magnetic iron- stone. WADD. This name is given to plum- bago, or black lead. WADD, BLACK. An ore of manga- nese found in Derbyshire. It is remarkable for the property of taking fire when mixed with linseed oil. WASH. The technical term for the fer- mented liquor, of whatever kind, from which spirit is intended to be distilled. See ALCO- HOL and DISTILLATION. WATER. It is scarcely necessary to give any definition or description of this uni- versally known fluid. It is a very transpa- rent fluid, possessing a moderate degree of activity with regard to organized substances, which renders it friendly to animal and vege- table life, for both which it is indeed indis- pensably necessary. Hence it acts but slightly on the organs of sense, and is therefore said to have neither taste nor smell. It appears to possess considerable elasticity, and yields in a perceptible degree to the pressure of air in the condensing machine, as Canton proved, by including it in an open glass vessel with a nar- row neck. The solubility or insolubility of bodies in this fluid composes a large part of the science of chemistry. See SALT. The habitudes of water with heat have been detailed under Caloric and Tempera- ture. Water is not only the common measure of specific gravities, but the tables of these may be usefully employed in the admeasurement of irregular solids ; for one cubic foot is very nearly equal to 1000 ounces avoirdupois. The numbers of the table denoting the specific gra- vities do therefore denote likewise the number of ounces avoirdupois in a cubic foot of each substance. Native water is seldom, if ever, found per- fectly pure. The waters that flow within or upon the surface of the earth contain various earthy, saline, metallic, vegetable, or animal particles, according to the substances over or through which they pass. Rain and snow waters are much purer than these, although they also contain whatever floats in the air, or has been exhaled along with the watery vapours. The purity of water may be known by the following marks or properties of pure water : 1. Pure water is lighter than water that is not pure. 2. Pure water is more fluid than water that is not pure. 3. It has no colour, smell, or taste. 4. It wets more easily than the waters con- taining metallic and earthy salts, called hard waters, and feels softer when touched. 5. Soap, or a solution of soap in alcohol, mixes easily and perfectly with it. 6. It is not rendered turbid by adding to it a solution of gold in aqua regia, or a solution of silver, or of lead, or of mercury, in nitric acid, or a solution of acetate of lead in water. For the habitudes of water with saline matter, see SALT, and the different sub- stances. Water was, till modern times, considered as an elementary or simple substance. Previous to the month of October 1776, the celebrated Macquer, assisted by M. Sigaud de la Fond, made an experiment by burning hydrogen gas in a bottle without explosion, and holding a white china saucer over the flame. His intention appears to have been that of ascertaining whether any fuliginous smoke was produced, and he observes that the saucer remained perfectly clean and white, but was moistened with perceptible drops of a clear fluid, resembling water ; and which, in fact, appeared to him and his assistant to be no- thing but pure water. He does not say whether any test was ap- plied to ascertain this purity, neither does he make any remark on the fact.* In the month of September 1777, Messrs. Bucquet and Lavoisier, not being acquainted with the fact which is incidentally and con- cisely mentioned by Macquer, made an ex- periment to discover what is produced by the combustion of hydrogen. They fired five or six pints of hydrogen in an open and wide- mouthed bottle, and instantly poured two ounces of lime water through the flame, agi- tating the bottle during the time the com- bustion lasted. The result of this experi- ment showed, that carbonic acid was not pro- duced, f Before the month of April 1781, Mr. John Warldre, encouraged by Dr. Priestley, fired a mixture of common air and hydrogen gas in a close copper vessel, and found its weight diminished. Dr. Priestley, likewise, before the same period, fired a like mixture of hy- drogen and oxygen gas in a closed glass vessel, Mr. Warltire being present. The inside of the vessel, though clean and dry before, be- came dewy, and was lined with a sooty sub- stance, t These experiments were afterwards repeated by Mr. Cavendish and Dr. Priestley; and it was found, that the diminution of weight did not take place, neither was the sooty matter * Dictionnaire de Chimie, 2d edition, Paris, 1778, Art. Gas Inflammable, vol. ii. p. 314, 315. f Acad. Par. 1781, p. 470. j Priestley, v. 395. AVAT 792 WAT perceived.* These circumstances, therefore, must have arisen from some imperfection in the apparatus or materials with which the former experiments were made. It was in the summer of the year 1781, that Mr. Henry Cavendish was busied in examining what becomes of the air lost by combustion, and made those valuable experiments which were read before the Royal Society on the 15th of January 1784.f He burned 500,000 grain measures of hydrogen gas, with about 2 times the quantity of common air, and by causing the burned air to pass through a glass tube eight feet in length, 135 grains of pure water were condensed. He also exploded a mixture of 19,500 grain measures of oxygen gas, and 37,000 of hydrogen, in a close vessel. The condensed liquor was found to contain a small portion of nitric acid, when the mixture of the air was such, that the burned air still contained a considerable proportion of oxygen. In this case it may be presumed, that some of the oxygen combines with a portion of nitro- gen present. In the mean time, M. Lavoisier continued his researches, and during the winter of 1781- 1782, together with M. Gingembre, he filled a bottle of six pints with hydrogen, which being fired, and two ounces of lime water poured in, was instantly stopped with a cork, through which a flexible tube communicating with a vessel of oxygen was passed. The in- flammation ceased, except at the orifice of the tube through which the oxygen was pressed, where a beautiful flame appeared. The com- bustion continued a considerable time, during which the lime water was agitated in the bottle. Neither this, nor the same experiment repeated with pure water, and with a weak solution of alkali instead of lime water, afforded the in- formation sought after, for these substances were not at all altered. The inference of Mr. Warltire, respecting the moisture on the inside of the glass in which Dr. Priestley first fired hydrogen and common air, was, that these airs, by combustion, de. posited the moisture they contained. Mr. Watt, however, inferred from these experi- ments, that water is a compound of the burned airs, which have given out their latent heat * Phil. Trans. Ixxiv. 12G. Dr. Priestley supposed the sooty matter to be part of the mercury used in filling the vessel, Phil. Trans. Ixxiv. 332. f M. Lavoisier relates, that Dr. Blagden, Sec. R. S. (who was present at the performing of the capital experiment of burning hydrogen and oxygen gas in a closed vessel on the 24th June 1783), informed him, that Mr. Cavendish had already done the same thing, and obtained water. See the Memoirs of the Royal Aca- demy at Paris for 1781, p. 472 ; also Phil. Trans, vol. Ixxiv. p. 134. by combustion ; and communicated his sen- timents to Dr. Priestley in a letter dated April 26, 1783. It does not appear, -J- that the composition of water was known or admitted in France, till the summer of 1783, when M. Lavoisier and M. de la Place, on the 24th of June, re- peated the experiment of burning hydrogen and oxygen in a glass vessel over mercury, in a still greater quantity than had been burned by Mr. Cavendish. The result was nearly five gros of pure water. ^ M. Monge made a similar experiment at Paris, nearly at the same time, or perhaps before. This assiduous and accurate philosopher then proceeded, in conjunction with M. Meus- nier, to pass the steam of water through a red- hot iron tube, and found that the iron was oxidized, and hydrogen disengaged ; and the steam of water being passed over a variety of other combustible or oxidable substances, pro- duced similar results, the water disappearing and hydrogen being disengaged. These ca- pital experiments were accounted for by M. Lavoisier, by supposing the water to be de- composed into its component parts, oxygen and hydrogen, the former of which unites with the ignited substance, while the latter is disengaged. The grand experiment of the composition of water by Fourcroy, Vauquelin, and Seguin, was begun on Wednesday, May 13, 1790, and was finished on Friday the 22d of the same month. The combustion was kept up 185 hours with little interruption, during which time the machine was not quitted for a moment. The experimenters alternately refreshed themselves when fatigued, by lying for a few hours on mattresses in the labo- ratory. To obtain the hydrogen, 1. Zinc was melted and rubbed into a powder in a very hot mortar. 2. This metal was dissolved in concentrated sulphuric acid diluted with seven parts of water. The air procured was made to pass through caustic alkali. To obtain the oxygen, two pounds and a half of crystallized hyper- oxymuriate of potash were distilled, and the air was transferred through caustic alkali. The volume of hydrogen employed was 25963 '568 cubic inches, and the weight was 1039-358 grains. The volume of oxygen was 12570-942, and the weight was 6209-869 grains. The total weight of both elastic fluids was 7249-227. * Phil. Trans, vol. Ixxiv. p. 330. t Compare Phil. Trans, vol. Ixxiv. p. 138, with the Memoirs of the Royal Academy at Paris for 1781, pages 472 and 474. I The ounce poids de marc being 472-2 grains troy, this quantity will be 295 English grains. WAT 793 WAT The weight of water obtained was 7244 grains, or 12 ounces 4 gros 45 grains. The weight of water which should have been obtained was 12 ounces 4 gros 49-227 grains. The deficit was 4-227 grains. The quantity of azotic air before the expe- riment was 415-256 cubic inches, and at the close of it 467- The excess after the expe- riment was consequently 51-744 cubic inches. This augmentation is to be attributed, the academicians think, to the small quantity of atmospheric air in the cylinders of the gaso- meters at the time the other airs were intro- duced. These additional 51 cubic inches could not arise from the hydrogen, for experiment showed that it contained no azotic air. Some addition of this last fluid, the experimenters think, cannot be avoided, on account of the construction of the machine. . The water being examined, was found to be as pure as distilled water. Its specific gra- vity to distilled water was as 18671 : 18670. The decomposition of water is most ele- gantly effected by ELECTRICITY; which see. The composition of water is best demon- strated by exploding 2 volumes of hydrogen and 1 of oxygen, in the eudiometer. They disappear totally, and pure water results. - A cubic inch of this liquid, at 60, weighs 252-52 grains, consisting of 28-06 grains hydrogen, and 224-46 oxygen. The bulk of the former ) gas is That of the latter is J 1325 cubic inches. 662 1987 Hence there is a condensation of nearly two thousand volumes into one; and one volume of water contains 662 volumes of oxygen. The prime equivalent of water is 1-125; composed of a prime of oxygen = 1-0 -f- a prime of hydrogen = 0-125; or 9 parts by weight of water consist of 8 oxygen -f- 1 hydrogen. WATER OF CRYSTALLIZATION. Many salts require a certain proportion of water to enable them to retain the crystalline form, and this is called their water of crystal- lization. Some retain this so feebly, that it flies off on exposure to the air, and they fall to powder. These are the efflorescent salts. Others have so great an affinity for water, that their crystals attract more from the air, in which they dissolve. These are the deli- quescent. WATERS (MINERAL). The exami- nation of mineral waters with a view to as- certain their ingredients, and thence then: me- dicinal qualities, and the means of compound- ing them artificially, is an object of consider- able importance to society. It is likewise a subject which deserves to be attended to, be- cause it affords no mean opportunity for the agreeable practice of chemical skill. But this investigation is more especially of im- portance to the daily purposes of life, and the success of manufactures. It cannot but be an interesting object, to ascertain the com- ponent parts and qualities of the waters daily consumed by the inhabitants of large towns and vicinities. A very minute portion of unwholesome matter, daily taken, may con- stitute the principal cause of the differences in salubrity which are observable in different places. And with regard to manufactures, it is well known to the brewer, the paper- maker, the bleacher, and a variety of other artists, of how much consequence it is to them, that this fluid should either be pure, or at least not contaminated with such principles as tend to injure the qualities of the articles they make. This analysis has accordingly employed the attention of the first chemists. Bergmarm has written an express treatise on the subject, which may be found in the first volume of the English translation of his Essays. Kirwan published a valuable volume on the analysis of waters. The topography of the place where these waters rise is the first thing to be considered. By examining the ooze formed by them, and the earth or stones through which they are strained and filtered, some judgment may be formed of their contents. In filtering through the earth, and meandering on its surface, they take with them particles of various kinds, which their extreme attenuation renders ca- pable of being suspended in the fluid that serves for their vehicle. Hence we shall some- times find in these waters siliceous, calcareous, or argillaceous earth ; and at other times, though less frequently, sulphur, magnesian earth, or, from the decomposition of carbo- nated iron, ochre. The following are the ingredients that may occur in mineral waters : 1. Ah- is contained in by far the greater number of mineral waters : its proportion does not exceed l-28th of the bulk of the water. 2. Oxygen gas was first detected in waters by Scheele. Its quantity is usually inconsi- derable ; and it is incompatible with the presence of sulphuretted hydrogen gas or iron. 3. Hydrogen gas was first detected in Buxton water by Dr. Pearson. Afterward it was discovered in Harrowgate waters by Dr. Garnet, and in those of Lemington Priors by Mr. Lambe. 4. Sulphuretted hygrogen gas constitutes the most conspicuous ingredient in those waters, which are distinguished by the name of hepatic or sulphurous. The only acids hitherto found in waters, except in combination with a base, are the carbonic, sulphuric, and boracic. 5. Carbonic acid was first discovered in WAT 794. WAT Pyrmont water by Dr. Brownrigg. It is the most common ingredient in mineral waters, 100 cubic inches of the water generally con- taining from 6 to 40 cubic inches of this acid gas. According to Westrumb, 100 cubic inches of Pyrmont water contain 187 cubic inches of it, or almost double its own bulk. 6. Sulphurous acid has been observed in several of the hot mineral waters in Italy, which are in the neighbourhood of volcanoes. 7. The boracic acid has also been observed in some lakes in Italy. The only alkali which has been observed in mineral waters, uncombined, is soda ; and the only earthy bodies are silex and lime. 8. Dr. Black detected soda in the hot mi- neral waters of Geyser and Rykum in Iceland ; but in most other cases the soda is combined with carbonic acid. 9. Silex was first discovered in waters by Bergmann. It was afterward detected in those of Geyser and Rykum by Dr. Black, and in those of Karlsbad by Klaproth. Hassenfratz observed it in the waters of Pougues, as Breze did in those of Pu. It has been found also in many other mineral waters. 10. Lime is said to have been found un- combined in some mineral waters ; but this has not been proved in a satisfactory manner. The only salts hitherto found in mineral waters are the following ; sulphates, nitrates, muriates, carbonates, and borates ; and of these the carbonates and muriates occur by far most commonly, and the borates and ni- trates most rarely. 11. Sulphate of soda is not uncommon, especially in those mineral waters which are distinguished by the epithet saline. 12. Sulphate of ammonia is found in mi- neral waters near volcanoes. 13. Sulphate of lime is exceedingly com- mon in water. Its presence seems to have been first detected by Dr. Lister in 1682. 14. Sulphate of magnesia is almost con- stantly an ingredient in those mineral waters which have purgative properties. It was de- tected in Epsom waters in 1610, and in 1696 Dr. Grew published a treatise on it. 15. Alum is sometimes found in mineral waters, but it is exceedingly rare. 16. Sulphate of iron occurs sometimes in volcanic mineral waters, and has even been observed in other places. 17' Sulphate of copper is only found in the waters which issue from copper mines. 18. Nitre has been found in some springs in Hungary, but it is exceedingly uncommon. 19. Nitrate of lime was first detected in water by Dr. Home, of Edinburgh, in 1756. It is said to occur in some springs in the sandy deserts of Arabia. 20. Nitrate of magnesia is said to have been found in some springs. 21. Muriate of potash is uncommon ; but it has lately been discovered in the mineral springs of Uhleaborg in Sweden by Julin. 22. Muriate of soda is so extremely com- mon in mineral waters, that hardly a single spring has been analyzed without detecting some of it. 23. Muriate of ammonia is uncommon, but it has been found in some mineral springs in Italy and Siberia. 24. Muriate of barytes is still more uncom- mon, but its presence in mineral waters has been announced by Bergmann. 25 and 26. Muriates of lime and magnesia are common ingredients. 27. Muriate of alumina has been observed by Dr. Withering, but it is very uncommon. 28. Muriate of manganese was mentioned by Bergmann as sometimes occurring in mi- neral waters. It has lately been detected by Lambe in the waters of Leniington Priors, but in an extremely limited proportion. 29. The presence of carbonate of potash in mineral waters has been mentioned by several chemists ; if it do occur, it must be in a very small proportion. 30. Carbonate of soda is, perhaps, one of the most common ingredients of these liquids, if we except common salt and carbonate of lime. 31. Carbonate of ammonia has been dis- covered in waters, but it is uncommon. 32. Carbonate of lime is found in almost all waters, and is usually held in solution by an excess of acid. It appears from the dif- ferent experiments of chemists, as stated by Mr. Kirwan, and especially from those of Berthollet, that water saturated with carbonic acid is capable of holding in solution 0-002 of carbonate of lime. Now water saturated with carbonic acid, at the temperature of 50, contains very nearly 0-002 of its weight of carbonic acid. Hence it follows that carbonic acid, when present in such quantity as to sa- turate waters, is capable of holdiag its own weight of carbonate of lime in solution. Thus we see 1000 parts by weight of water, when it contains two parts of carbonic acid, is ca- pable of dissolving two parts of carbonate of lime. When the proportion of water is in- creased, it is capable of holding the carbonate of lime in solution, even when the proportion of carbonic acid united with it is diminished. Thus 24,000 parts of water are capable of holding two parts of carbonate of lime in so- lution, even when they contain only one part of carbonic acid. The greater the proportion of water, the smaller proportion of carbonic acid is necessary to keep the lime in solution ; and when the water is increased to a certain proportion, no sensible excess of carbonic acid is necessary. It ought to be remarked also, that water, however small a quantity of car- bonic acid it contains, is capable of holding carbonate of lime in solution, provided the weight of the carbonic acid present exceed WAT 795 WAT that of the lime. These observations apply equally to the other earthy carbonates held in solution by mineral waters. 33. Carbonate of magnesia is also very common in mineral waters, and is almost always accompanied by carbonate of lime. 34. Carbonate of alumina is said to have been found in waters, but its presence has not been properly ascertained. 35. Carbonate of iron is by no means un- common ; indeed it forms the most remarkable ingredient in those waters, which are distin- guished by the epithet of chalybeate. 36. Borax exists in some lakes in Persia and Thibet, but the nature of these waters has not been ascertained. 37 and 38. The hydrosulphurets of lime and of soda have been frequently detected in those waters which are called sulphurous, or hepatic. Mr. Westrumb says, that all sulphurous waters contain more or less hydrosulphuret of lime. To detect this he boiled the mineral water, excluding the contact of atmospheric air, to expel the sulphuretted hydrogen gas and car- bonic acid. Into the water thus boiled he poured sulphuric acid, when more sulphuretted hydrogen gas was evolved, and sulphate of lime was thrown down; fuming nitric acid, which separated from it sulphur ; and oxalic acid, which expelled sulphuretted hydrogen, and formed oxalate of lime. The water eva- porated in open vessels let fall sulphate of lime, and gave out sulphuretted hydrogen gas. To ascertain the quantity of sulphuretted hydrogen gas and carbonic acid, Mr. West- rumb proceeded as follows : He introduced the sulphurous water into a matrass, till it was filled to a certain point, which he marked ; fitted to it a curved tube, which terminated in a long cylinder ; filled this cylinder with lime water for the one experiment, and with acetate of lead, with excess of acid, for the other ; luted the apparatus ; and boiled the water till no more gas was expelled. When the lime water is used, carbonate of lime is precipitated in the proportion of 20 grains to every 10 cubic inches of carbonic acid gas ; when the solution of acetate of lead, hydro- sulphuret of lead, is thrown down, in the pro- portion of 19 grains to 10 cubic inches of sul- phuretted hydrogen gas. Beside these substances, certain vegetable and animal matters have been occasionally ob- served in mineral waters. But in most cases these are rather to be considered in the light of accidental mixtures, than of real component parts of the waters in which they occur. From this synoptical view of the different ingredients contained in mineral waters, it is evident that these substances occur in two dif- ferent distinct states: viz. 1. as being sus- pended in them ; and 2. as being dissolved in them chiefly in the form of a salt. The investigation of mineral waters con- sists, 1. In the examination of them by the senses : 2. In the examination of them by re- agents : 3. In the analysis properly so called. The examination by the senses consists in observing the effect of the water as to appear- ance, smell, and taste. The appearance of the water, the instant in which it is pumped out of the well, as well as after it has stood for some time, affords seve- ral indications, from which we are enabled to form a judgment concerning its contents. If the water be turbid at the well, the substances are suspended only, and not dissolved ; but if , the water be clear and transparent at the well, and some time intervenes before it becomes turbid, the contents are dissolved by means of carbonic acid. The presence of this gas is likewise indi- cated by small bubbles, that rise from the bottom of the well, and burst in the ir while they are making their escape, though the water at the same time perhaps has not an acid taste. This is the case, according to Count Razou- mowski, with respect to the tepid spring in Vallais, and the cold vitriolated chalybeate springs at Astracan. But the most evident proof of a spring containing carbonic acid is the generation of bubbles on the water being shaken, and their bursting with more or less noise, while the air is making its escape. The sediment deposited by the water in the well is likewise to be examined : if it be yel- low, it indicates the presence of iron ; if black, that of iron combined with sulphur ; but cha- lybeate waters being seldom sulphuretted, the latter occurs very rarely. As to the colour of the water itself, there are few instances where this can give any indication of its contents, as there are not many substances that colour it. The odour of the water serves chiefly to discover the presence of sulphuretted hydro- gen in it: such waters as contain this sub- stance have a peculiar fetid smell, somewhat resembling rotten eggs. The taste of a spring, provided it be per- fectly ascertained by repeated trials, may afford some useful indications with respect to the contents. It may be made very sensible by tasting water in which the various salts that are usually found in such waters are dissolved in various proportions. There is no certain dependence, however, to be placed on this mode of investigation ; for in many springs, the taste of sulphate of soda is disguised by that of the sea salt united with it. The water too is not only to be tasted at the spring, but after it has stood for some time. This pre- caution must be particularly observed with re- spect to such waters as are impregnated with carbonic acid; for the other substances con- tained in them make no impression on the tongue, till the carbonic acid has made its escape ; and it is for the same reason, that WAT 796 WAT thes waters must be evaporated in part, and then tasted again. Though the specific gravity of any water contributes but very little towards determining its contents, still it may not be entirely use- less to know the specific weight of the water, the situation of the spring, and the kind of sediment deposited by it. The examination of the water by means of reagents shows what they contain, but not how much of each principle. In many in- stances this is as much as the inquiry de- mands ; and it is always of use to direct the proceedings in the proper analysis. It is absolutely necessary to make the ex- periment with water just taken up from the spring, and afterward with such as has been exposed for some hours to the open air ; and sometimes a third essay is to be made with a portion of the water that has been boiled and afterward filtered. If the water contain but few saline particles, it must be evaporated ; as even the most sensible reagents do not in the least affect it, if the salts, the presence of which is to be discovered by them, are diluted with too great a quantity of water. Now, it may happen, that a water shall be impreg- nated with a considerable number of saline particles of different kinds, though some of them may be present in too small a quantity ; for which reason the water must be examined a second time, after having been boiled down to three-fourths. The substances of which the presence is discoverable by reagents are : 1. Carbonic acid. When this is not com- bined with any base, or not with sufficient to neutralize it, the addition of lime water will throw down a precipitate soluble with effer- vescence in muriatic acid. The infusion of litmus is reddened by it ; but the red colour gradually disappears, and may be again re- stored by the addition of more of the mineral water. When boiled it loses the property of reddening the infusion of litmus. According to Pfaff, the most sensible test of this acid is acetate of lead. 2. The mineral acids, when present uncom- bined in water, give the infusion of litmus a permanent red, even though the water nas been boiled. Bergmann has shown, that paper stained with litmus is reddened when dipped into water containing ^g T of sulphuric acid. 3. Water containing sulphuretted hydrogen gas is distinguished by the following proper- ties : It exhales the peculiar odour of sulphur- etted hydrogen gas. It reddens the infusion of litmus fugaciously. It blackens paper dipped into a solution of lead, and precipitates the nitrate of silver black or brown. 4. Alkalis, and alkaline and earthy carbon- ates, are distinguished by the following tests : The infusion of turmeric, or paper stained with turmeric, is rendered brown by alkalis; or reddish-brown, if the quantity be minute. This change is produced when the soda in water amounts only to 53^7- part. Paper stained with brasil wood, or the infusion of brasil wood, is rendered blue ; but this change is produced also by the alkaline and earthy carbonates. Bergmann ascertained, that water containing 7^3- part of carbonate of soda reddens paper stained with brasil wood blue. Litmus paper reddened by vinegar is restored to its original blue colour. This change is produced by the alkaline and earthy carbon- ates also. When these changes are fugacious, we may conclude, that the alkali is ammonia. 5. Fixed alkalis exist in water that occa- sions a precipitate with muriate of magnesia after being boiled. Volatile alkali may be distinguished by the smell ; or it may be ob- tained in the receiver by distilling a portion of the water gently, and then it may be distin- guished by the above tests. 6. Earthy and metallic carbonates are pre- cipitated by boiling the water containing them ; except carbonate of magnesia, which is pre- cipitated but imperfectly. 7- Iron is discovered by the following tests : The addition of tincture of galls gives water, containing iron, a purple or black colour. This test indicates the presence of a very minute portion of iron. If the tincture have no effect upon the water, after boiling, though it co- lours it before, the iron is in the state of a carbonate. The following observations of Westrumb on the colour which iron gives to galls, as modified by other bodies, deserve at- tention. A violet indicates an alkaline car- bonate, or earthy salt. Dark purple indicates other alkaline salts. Purplish-red indicates sulphuretted hydrogen gas. Whitish, and then black, indicates sulphate of lime. Mr. Phillips has lately ascertained, that, while the iron is little oxided, the presence of lime rather facilitates the application of this test ; but the lime prevents the test from acting, provided the iron be considerably oxidized. The prus- sian alkali occasions a blue precipitate in water containing iron. If an alkali be present, the blue precipitate does not appear, unless the alkali is saturated with an acid. 8. Sulphuric acid exists in waters that form a precipitate with the following solutions : Muriate, nitrate, or acetate of bary tes, strontian, or lime, or nitrate or acetate of lead. Of these the most powerful by far is muriate of barytes, which is capable of detecting the presence of sulphuric acid uncombined, when it does not exceed the millionth part of the water. Ace- tate of lead is next in point of power. The muriates are more powerful than the nitrates. The calcareous salts are least powerful. All these tests are capable of indicating a much smaller proportion of uncombined sulphuric acid, than when it is combined with a base. To render muriate of barytes a certain test of sulphuric acid, the following precautions must be observed: The muriate must be diluted; WAT 797 WAT the alkalis or alkaline carbonates, if the water contain any, must be previously saturated with muriatic acid ; the precipitate must be inso- luble in muriatie acid ; if boracic aaid be sus- pected, muriate of strontian must be tried, which is not precipitated by boracic acid. The hydrosulphurets precipitate barytic solutions, but their presence is easily discovered by the smell. 9. Muriatic acid is detected by nitrate of silver, which occasions a white precipitate, or a cloud, in water containing an exceedingly minute portion of this acid. To render this test certain, the following precautions are ne- cessary: The alkalis or carbonates must be previously saturated with nitric acid. Sul- phuric acid, if any be present, must be pre- viously removed by means of nitrate of ba- rytes. The precipitate must be insoluble in nitric acid. PfafY says, that the mild nitrate of mercury is the most sensible test of muriatic acid; and that the precipitate is not soluble in an excess of any acid. 10. Boracic acid is detected by means of acetate of lead, with which it forms a precipi- tate insoluble in acetic acid. But to render this test certain, the alkalis and earths must be previously saturated with acetic acid, and the sulphuric and muriatic acids removed by means of acetate of strontian and acetate of silver. 11. Barytes is detected by the insoluble white precipitate which it forms with diluted sulphuric acid. 12. Lime is detected by means of oxalic acid, which occasions a white precipitate ' in water containing a very minute proportion of this earth. To render this test decisive, the following precautions are necessary: The mineral acids, if any be present, must be pre- viously saturated with an alkali. Barytes, if any be present, must be previously removed by means of sulphuric acid. Oxalic acid pre- cipitates magnesia but very slowly, whereas it precipitates lime instantly. 13. Magnesia and alumina. The presence of these earths is ascertained by the following tests : Pure ammonia precipitates them both, and no other earth, provided the carbonic acid have been previously separated by a fixed al- kali and boiling. Lime water precipitates only these two earths, provided the carbonic acid be previously removed, and the sulphuric acid also, by means of nitrate of barytes. The alumina may be separated from the magnesia, after both have been precipitated together, either by boiling the precipitate in caustic potash, which dissolves the alumina and leaves the magnesia; or the precipitate may be dissolved in muriatic acid, precipi- tated by an alkaline carbonate, dried in the temperature of 100, and then exposed to the action of diluted muriatic acid, which dissolves the magnesia without touching the alumina. 14. Silex may be ascertained by evapo- rating a portion of water to dryness, and re- dissolving the precipitate in muriatic acid. The silex remains behind undissolved. By these means we may detect the pre- sence of the different substances commonly found in waters; but as they are generally combined so as to form salts, it is necessary we should know what these combinations are. This is a more difficult task, which Mr. Kir- wan teaches us to accomplish by the following methods : 1. To ascertain the presence of the different sulphates. The sulphates which occur in water are seven; but one of these, namely, sulphate of copper, is so uncommon, that it maj- be ex- cluded altogether. The same remark applies to sulphate of ammonia. It is almost unne- cessary to observe, that no sulphate need be looked for, unless both its acid and base have been previously detected in the water. Sulphate of soda may be detected by the following method : Free the water to be ex- amined of all earthy sulphates, by evaporating it to one-half, and adding lime water as long as any precipitate appears. By these means the earths will all be precipitated except lime, and the only remaining earthy sulphate will be sulphate of lime, which will be separated by evaporating the liquid till it becomes con- centrated, and then dropping into it a little alcohol, and, after filtration, adding a little oxalic acid. With the water thus purified, mix solution of lime. If a precipitate appear, either im- mediately, or on the addition of a little alco- hol, it is a proof that sulphate of potash or of soda is present. Which of the two may be determined, by mixing some of the purified water with acetate of barytes. Sulphate of barytes precipitates. Filter and evaporate to dryness. Digest the residuum in alcohol. It will dissolve the alkaline acetate. Evaporate to dryness, and the dry salt will deliquesce if it be acetata of potash, but effloresce if it be acetate of soda. Sulphate of lime may be detected by eva- porating the water suspected to contain it to a few ounces. A precipitate appears, which, if it be sulphate of lime, is soluble in 500 parts of water ; and the solution affords a precipitate with the muriate of barytes, oxalic acid, car- bonate of magnesia, and alcohol. Alum may be detected by mixing carbon- ate of lime with the water suspected to con- tain it. If a precipitate appear, it indicates the presence of alum, or at least of sulphate of alumina ; provided the water contains no muriate of barytes or metallic sulphates. The first of these salts is incompatible with alum : the second may be removed by the alkaline prussiates. When a precipitate is produced in water by muriate of lime, carbonate of lime, and muriate of magnesia, we may conclude that it contains alum or sulphate of alumina. Sulphate of magnesia may be detected by WAT 798 WAT means of hydrosulphuret of strontian, which occasions an immediate precipitate with this salt, and with no other ; provided the water be previously deprived of alum, if any be pre- sent, by means of carbonate of lime, and pro- vided also that it contains no uncombined acid. Sulphate of iron is precipitated from water by alcohol, and then it may be easily recog- nized by its properties. 2. To ascertain the presence of the different muriates. The muriates found in waters amount to eight, or to nine, if muriate of iron be in- cluded. The most common by far is muriate of soda. Muriate of soda and of potash may be de- tected by the following method: Separate the sulphuric acid by alcohol and nitrate of barytes. Decompose the earthy nitrates and muriates by adding sulphuric acid. Expel the excess of muriatic and nitric acids by heat. Separate the sulphates thus formed by alcohol and barytes water. The water thus purified can contain nothing but alkaline nitrates and muriates. If it form a precipitate with acetate of silver, we may conclude that it contains muriate of soda or of potash. To ascertain which, evaporate the liquid thus precipitated to dryness. Dissolve the acetate in alcohol, and again evaporate to dryness. The salt will deliquesce, if it be acetate of potash ; but effloresce, if it be acetate of soda. The potash salts are most readily distin- guished by the precipitate which they afford to muriate of platinum, which the soda salts do not occasion. Muriate of barytes may be detected by sulphuric acid, as it is the only barytic salt hitherto found in water. Muriate of lime may be detected by the following method : Free the water from sulphate of lime and other sulphates, by eva- porating it to a few ounces, mixing it with alcohol, and adding last of all nitrate of barytes as long as any precipitate appears. Filter the water ; evaporate to dryness ; treat the dry mass with alcohol; evaporate the alcohol to dryness; and dissolve the residuum in water. If this solution give a precipitate with acetate of silver and oxalic acid, it may contain muriate of lime. It must contain it in that case, if, after being treated with carbonate of lime, it give no precipitate with ammonia. If the liquid in the receiver give a precipitate with nitrate of silver, muriate of lime existed in the water. Muriate of magnesia may be detected by separating all the sulphuric acid by means of nitrate of barytes. Filter, evaporate to dry- ness, and treat the dry mass with alcohol. Evaporate the alcoholic solution to dryness, and dissolve the residuum in water. The muriate of magnesia, if the water contained any, will be found in this solution. Let us suppose, that, by the tests formerly described, the presence of muriatic acid and of magnesia, in this solution, has been ascertained. In that case, if carbonate of lime afford no precipitate, and if sulphuric acid and evaporation, together with the addition of a little alcohol, occasion no precipitate, the solution contains only muriate of magnesia. If these tests give precipitates, we must separate the lime which is present by sulphuric acid and alcohol, and distil off the acid with which it was combined. Then the magnesia is to be separated by the oxalic acid and alcohol, and the acid with which it was united is to be distilled off. If the liquid in the retort give a precipitate with nitrate of silver, the water contains muriate of magnesia. Muriate of alumina may be discovered by saturating the water, if it contain an excess of alkali, with nitric acid, and by separating the sulphuric acid by means of nitrate of barytes. If the liquid, thus purified, give a precipitate with carbonate of lime, it contains muriate of alumina. The muriate of iron or of man- ganese, if any be present, is also decomposed, and the iron precipitated by this salt. The precipitate may be dissolved in muriatic acid, and the alumina, iron, and manganese, if they be present, may be separated by the rules laid down' below. 3. To ascertain the presence of the different nitrates. The nitrates but seldom occur in waters ; but when they do, they may be de- tected by the following results : Alkaline nitrates may be detected by freeing the water examined from sulphuric acid by means of acetate of barytes, and from muriatic acid by acetate of silver. Evaporate the filtered liquid, and treat the dry mass with alcohol ; what the alcohol leaves can consist only of the alkaline nitrates and acetate of lime. Dissolve it in water. If carbonate of magnesia occasion a precipitate, lime is present. Separate the lime by means of carbonate of magnesia. Filter and evaporate to dryness, and treat the dried mass with alcohol. The alcohol now leaves only the alkaline nitrates, which may be easily recognized, and distin- guished by their respective properties. Mr. Faraday has lately detected nitric acid in the form of a nitrate in a Cheltenham water, called the orchard well. On adding sulphuric acid to a portion of this water in quantity abundantly sufficient to decompose all the salts subject to its action, and boiling such acidulated water in a Florence flask, with a leaf of gold, for half an hour, or an hour, the gold either in part or entirely disappeared, and a solution was obtained, which, when tested by proto-muriate of tin, gave a deep purple tint. Hence, the presence of nitric acid originally in the water was inferred ; and that no mistake might occur, a solution was made in pure water of all the salts except the nitrate found in the water, boiled with some of the same sulphuric acid, and tested by the same WAT 799 WAT muriate of tin ; but in this case no colour was afforded, or any gold dissolved. Journal of Science, xvii. 178. Nitrate of lime. To detect this salt, con- centrate the water, and mix it with alcohol to separate the sulphates. Filter, and distil off the alcohol ; then separate the muriatic acid by acetate of silver. Filter, evaporate to dryness, and dissolve the residuum in alcohol. Evaporate to dryness, and dissolve the dry mass in water. If this last solution indicate the presence of lime by the usual tests, the water contained nitrate of lime. To detect nitrate of magnesia, the water is to be freed from sulphates and muriates exactly as described in the last paragraph. The liquid thus purified is to be evaporated to dryness, and the residuum treated with alcohol. The alcoholic solution is to be evaporated to dryness, and the dry mass dissolved in water. To this solution potash is to be addtd, as long as any precipitate appears. The solution, filtered, and again evaporated to dryness, is to be treated with alcohol. If it leave a residuum consisting of nitre (the only residuum which it can leave), the water contained nitrate of magnesia. Such are the methods by which the presence of the different saline contents of waters may be ascertained. The labour of analysis may be considerably shortened, by observing that the following salts are incompatible with each other, and cannot exist together in water, except in very minute proportion : Salts. Incompatible with f Nitrates of lime and mag- Fixed alkaline ) nesia, sulphates ^ Muriates of lime and mag- V nesia. Alkalis, Sulphate of lime -J Carbonate of magnesia, Muriate of barytes. ' Alkalis, Muriate of barytes, Nitrate, muriate, carbonate of lime, .Carbonate of magnesia. f Alkalis, ^ Muriate of barytes, \ Nitrate and muriate V. lime. C Alkalis, Sulphate of iron< Muriate of barytes, { Earthy carbonates. I Sulphates, 1 Alkaline carbonates, ( Earthy carbonates. i Sulphates, except of lime, Muriate of lime < Alkaline carbonates, ( Earthy carbonates. Muriate of mag- f Alkaline carbonates, nesia \ Alkaline sulphates. f Alkaline carbonates, 1 (.Sulphates, except of lime. Alum Sulphate of magnesia Muriate of barytes of Nitrate of lime Beside the substances above described, there is sometimes found in water a quantity of bitumen combined with alkali, and in the state of soap. In such waters acids occasion a coagulation ; and the coagulum collected on a filter discovers its bitumous nature by its combustibility. Water also sometimes contains extractiv matter; the presence of which may be detected by means of nitrate of silver. The water suspected to contain it must be freed from sulphuric and nitric acid by means of nitrate of lead ; after this, if it give a brown preci- pitate with nitrate of silver, we may conclude that extractive matter is present. But it is not sufficient to know that a mineral water contains certain ingredients ; it is necessary to ascertain the proportions of these, and thus we arrive at then* complete analysis. 1. The different aerial fluids ought to be first separated and estimated. For this purpose, a retort should be filled two-thirds with the water, and connected with a jar full of mercury, standing over a mercurial trough. Let the water be made to boil for a quarter of an hour. The aerial fluids will pass over into the jar. When the apparatus is cool, the quantity of air expelled from the water may be determined either by bringing the mercury within and without the jar to a level ; or if this cannot be done, by reducing the air to the proper density by calculation. The air of the retort ought to be carefully subtracted, and the jar should be divided into cubic inches and tenths. The only gaseous bodies contained in water are, common air, oxygen gas, nitrogen gas, carbonic acid, sulphuretted hydrogen gas, and sulphurous acid. The last two never exist in water together. The presence of either of them must be ascertained previously by the application of the proper tests. If sulphuretted hydrogen gas be present, it will be mixed with the air contained in the glass jar, and must be separated before this air be examined. For this purpose the jar must be removed into a tub of warm water, and nitric acid introduced, which will absorb the sulphuretted hydrogen. The residuum is then to be again put into a mercurial jar, and examined. If the water contain sulphurous acid, this previous step is not necessary. Introduce into the air a solution of pure potash, and agitate the whole gently. The carbonic acid and sulphurous acid gas will be absorbed, and leave the other gases. The bulk of this residuum, subtracted from the bulk of the whole, will give the bulk of the carbonic acid and sulphurous acid absorbed. Evaporate the potash slowly, almost to dryness, and leave it exposed to the atmo- sphere. Sulphate of potash will be formed, which may be separated by dissolving the carbonate of potash by means of diluted mu- riatic acid, and filtering the solution. 100 grains of sulphate of potash indicate 36-4 WAT 800 WAT grains of sulphurous acid, or 53-66 cubic inches of that acid in the state of gas. The bulk of sulphurous acid gas ascertained by this method, subtracted from the bulk of the gas absorbed by the potash, gives the bulk of the carbonic acid gas. Now 100 cubic inches of carbonic acid, at the temperature of 60 and barometer 30 inches, weigh 46-6 grains. Hence it is easy to ascertain its weight. The gas remaining may be examined by the common eudiometrical processes. When a water contains sulphuretted hy- drogen gas, the bulk of this gas is to be ascertained in the following manner: Fill three-fourths of a jar with the water to be examined, and invert it in a water trough, and introduce a little nitrous gas. This gas, mixing with the air in the upper part of the jar, will form nitrous acid, which will render the water turbid, by decomposing the sul- phuretted hydrogen, and precipitating sulphur. Continue to add, nitrous gas at intervals as long as red fumes appear, then turn up the jar and blow out the air. If the hepatic smell continue, repeat this process. The sulphur precipitated indicates the proportion of hepatic gas in the water ; one grain of sulphur in- dicating the presence of nearly 3 cubic inches of this gas. 2. After having estimated the gaseous bodies, the next step is to ascertain the proportion of the earthy carbonates. For this purpose it is necessary to deprive the water of its sulphuretted hydrogen, if it contain any. This may be done, either by exposing it to the air for a considerable time, or treating it with litharge. A sufficient quantity of the v/ater, thus purified if necessary, is to be boiled fora quarter of an hour, and filtered when cool. The earthy carbonates remain on the filter. The precipitate thus obtained may be carbonate of lime, of magnesia, of iron, of alumina, or even sulphate of lime. Let us suppose all of these substances to be present together. Treat the mixture with diluted muriatic acid, which will dissolve the whole except the alumina and sulphate of lime. Dry this residuum in a red heat, and note the weight. Then boil it in carbonate of soda, saturate the soda with muriatic acid, and boil the mixture for half an hour. Carbonate of lime and alumina precipitate. Dry this pre- cipitate, and treat it with acetic acid. The lime will be dissolved, and the alumina will remain. Dry it and weigh it. Its weight, subtracted from the original weight, gives the proportion of sulphate of lime. The muriatic solution contains lime, mag- nesia, and iron. Add ammonia as long as a reddish precipitate appears. The iron and part of the magnesia are thus separated. Dry the precipitate, and expose it to the air for some time in a heat of 200^ ; then treat it with acetic acid to dissolve the magnesia ; which solution is to be added to the muriatic solu- tion. The iron is to be redissolved in muriatic acid, precipitated by an alkaline carbonate, dried and weighed. Add sulphuric acid to die muriatic solution as long as any precipitate appears ; then heat the solution and concentrate. Heat the sul- phate of lime thus obtained to redness, and weigh it. 100 grains of it are equivalent to 74-7 of carbonate of lime dried. Precipitate the magnesia by means of carbonate of soda. Dry it and weigh it. But as part remains in solution, evaporate to dryness, and wash the residuum with a sufficient quantity of distilled water, to dissolve the muriate of soda and sulphate of lime, if any be still present. What remains behind is carbonate of magnesia. Weigh it, and add its weight to the former. The sulphate of lime, if any, must also be separated and weighed. 3. We have next to ascertain the proportion of mineral acids or alkalis, if any be present uncombined. The acids which may be present, omitting the gaseous, are the sulphuric, mu- riatic, and boracic. The proportion of sulphuric acid is easily determined. Saturate it with barytes water, and ignite the precipitate. 100 grains of sulphate of barytes thus formed, indicate 34-0 of real sulphuric acid. Saturate the muriatic acid with barytes water, and then precipitate the barytes by sulphuric acid. 100 parts of the ignited precipitate are equivalent to 23-73 grains of real muriatic acid. Precipitate the boracic acid by means of acetate of lead. Decompose the borate of lead by boiling it in sulphuric acid. Evaporate to dryness. Dissolve the boracic acid in alcohol, and evaporate the solution ; the acid left behind may be weighed. To estimate the proportion of alkaline carbonate present in a water containing it, saturate it with sulphuric acid, and note the weight of real acid necessary. Now 100 grains of real sulphuric acid saturate 120.0 potash, and 80-0 soda. 4. The alkaline sulphates may be estimated by precipitating their acid by means of nitrate of barytes, having previously freed the water from all other sulphates; for 14-75 grains of ignited sulphate of barytes indicate 9-0 grains of dried sulphate of soda; while 14-75 sul- phate of barytes indicate 11 of dry sulphate of potash. Sulphate of lime is easily estimated by evaporating the liquid containing it to a few ounces (having previously saturated the earthy carbonates with nitric acid), and precipitating the sulphate of lime by means of weak alcohol. It may then be dried and weighed. The quantity of alum may be estimated by precipitating the alumina by carbonate of lime or of magnesia, (if no lime be present in the liquid). Eleven grains of the alumina, heated to incandescence, indicate 100 of crystallized alum, or 55 of dried salt. Sulphate of magnesia may be estimated, WAT 301 WAT provided no other sulphate be present, by precipitating the acid by means of a barytic salt, as 14-75 parts of ignited sulphate of ba- rytes indicate 7-5 of sulphate of magnesia. If sulphate of lime, and no other sulphate, accompany it, this may be decomposed, and the lime precipitated by carbonate of mag- nesia. The weight of the lime thus obtained enables us to ascertain the quantity of sulphate of lime contained in the water. The whole of the sulphuric acid is then to be precipitated by barytes. This gives the quantity of sulphuric acid ; and subtracting the portion which bs- longs to the sulphate of lime, there remains that which was combined with the magnesia, from which the sulphate of magnesia may be easily estimated. If sulphate of soda be present, no earthy nitrate or muriate can exist. Therefore, if no other earthy sulphate be present, the magnesia may be precipitated by soda, dried and weighed ; 2-5 grains of which indicate 7-5 grains of dried sulphate of magnesia. The same process succeeds when sulphate of lime accompanies these two sulphates ; only in this case the precipitate, which consists both of lime and magnesia, is to be dissolved in sulphuric acid evaporated to dryness, and treated with twice its weight of cold water, which dissolves the sulphate of magnesia, and leaves the other salt. Let the sulphate of magnesia be evaporated to dryness, exposed to a heat of 400, and weighed. The same process succeeds, if alum be present instead of sulphate of lime. The precipitate in this case, previously dried, is to be treated with acetic acid, which dissolves the magnesia, and leaves the alumina. The magnesia may be again precipitated, dried, and weighed. If sulphate of iron be present, it may be separated by exposing the water to the air for some days, and mixing with it a portion of alumina. Both the oxide of iron and the sulphate of alumina, thus formed, precipitate in the state of an insoluble powder. The sulphate of magnesia may then be esti- mated by the rules above given. Sulphate of iron may be estimated by pre- cipitating the iron by means of prussic alkali, having previously determined the weight of the precipitate produced by the prussiate in a solution of a given weight of sulphate of iron in water. If muriate of iron be also present, which is a very rare case, it may be separated by evaporating the water to dryness, and treating the residuum with alcohol, which dissolves the muriate, and leaves the sulphate. 5. If muriate of potash, or of soda, without any other salt, exist in water, we have only to decompose them by nitrate of silver, and dry the precipitate ; for 18.25 of muriate of silver indicate 9-5 of muriate of potash ; and 18-25 of muriate of silver indicate 1-5 of com- mon salt. The same process is to be followed, if the alkaline carbonates be present; only these carbonates must be previously saturated with sulphuric acid; and we must precipitate the muriatic acid by means of sulphate of silver instead of nitrate. The presence of sulphate of soda does not injure the success of this process. If muriate of ammonia accompany either of the fixed alkaline sulphates, without the presence of any other salt ; decompose the sal ammoniac by barytes water, expel the ammo- nia by boiling, precipitate the barytes by diluted sulphuric acid, and saturate the muri- atic acid with soda. The sulphate of barytes thus precipitated indicates the quantity of muriate of ammonia, 14-75 grains of sulphate indicating 6-75 grains of this salt If any sulphates be present in the solution, they ought to be previously separated. If common salt be accompanied by muriate of lime, muriate of magnesia, muriate of alu- mina, or muriate of iron, or by all these together, without any other salt, the earths may be precipitated by barytes water, and redissolved in muriatic acid. They are then to be separated from each other by the rules formerly laid down, and their weight, being determined, indicates the quantity of every particular earthy muriate contained in the water. For 50 grains of lime indicate 100 of dried muriate of lime ; 30 grains of magnesia indicate 100 of the muriate of that earth ; and 21-8 grains of alumina indicate 100 of the muriate of alumina. The barytes is to be separated from the solution by sulphuric acid, and the muriatic acid expelled by heat, or saturated with soda; the common salt may then be ascertained by evaporation, subtract- ing in the last case the proportion of common salt indicated by the known quantity of muri- atic acid from which the earths had been separated. When sulphates and muriates exist toge- ther, they ought to be separated either by precipitating the sulphates by means of alco- hol, or by evaporating the whole to dryness, and dissolving the earthy muriates in alcohol. The salts thus separated may be estimated by the rules already laid down. When alkaline and earthy muriates and sulphate of lime occur together, the last is to be decomposed by means of muriate of ba- rytes. The precipitate ascertains the weight of sulphate of lime contained in the water. The estimation is then to be conducted as when nothing but muriates are present, only from the muriate of lime that proportion of muriate must be deducted which is known to have been formed by the addition of the muri- ate of barytes. When muriates of soda, magnesia, and alumina are present together with sulphates of lime and magnesia, the water to be exa- mined ought to be divided into two equal portions. To the one portion add carbonate of magnesia till the whole of the lime and o F" WAT 802 WAT alumina is precipitated. Ascertain the quan- tity of lime which gives the proportion of sulphate of lime. Precipitate the sulphuric acid by muriate of barytes. This gives the quantity contained in the sulphate of mag- nesia and sulphate of lime : subtracting this last portion, we have the quantity of sulphate of magnesia. From the second portion of water, precipi- tate all the magnesia and alumina by means of lime water. The weight of these earths enables us to ascertain the weight of muriate of magnesia and of alumina contained in the water, subtracting that, part of the magnesia which existed in the state of sulphate, as indi- cated by the examination of the first portion of water. After this estimation, precipitate tha sulphuric acid by barytes water, and the lime by carbonic acid. The liquid, evaporated to dry ness, leaves the common salt. 6. It now only remains to explain the me- thod of ascertaining the proportion of the ni- trates which may exist in waters. When nitre accompanies sulphates and muriates without any other nitrates, the sul- phates are to be decomposed by acetate of ba- rytes, and the muriates by acetate of silver. The water, after filtration, is to be evaporated to dryness, and the residuum treated with al- cohol, which dissolves the acetates, and leaves the nitre, the quantity of which may be easily calculated. If an alkali be present, it ought to be previously saturated with sulphuric or muriatic acid. If nitre, common salt, nitrate of lime, and muriate of lime or magnesia, be present toge- ther, the water ought to be evaporated to dry- ness, and the dry mass treated with alcohol, which takes up the earthy salts. From the residuum, redissolved in water, the nitre may be separated, and calculated as in the last case. The alcoholic solution is to be evapo- rated to dryness. and the residuum redissolved in water. Let us suppose it to contain muri- ate of magnesia, nitrate of lime, and muriate of lime. Precipitate the muriatic acid by ni- trate of silver, which gives the proportion of muriate of magnesia and of lime. Separate the magnesia by means of carbonate of lime, and note its quantity. This gives the quan- tity of muriate of magnesia ; and subtracting the muriatic acid contained in that salt from the whole acid indicated by the precipitate of silver, we have the proportion of muriate of lime. Lastly, saturate the lime added to pre- cipitate the magnesia with nitric acid. Then precipitate the whole of the lime by sulphuric acid ; and subtracting from the whole of the sulphate thus formed that portion formed by the carbonate of lime added, and by the lime contained in the muriate, the residuum gives us the lime contained in the original nitrate ; and 35 grains of lime form 102-5 of dry nitrate of lime. In the year 1807, Dr. Marcet advanced some new ideas on the art of analyzing mine- ral waters, in an admirable paper on the water of the Dead Sea, inserted in the Phil. Trans- actions. " It is satisfactory to observe," says this excellent chemist, " that Dr. Murray adopted, several years afterwards, a mode of proceeding precisely similar, and indeed that he proposed, in a subsequent paper, a general formula for the analysis of mineral waters, in which this method is pointed out, as likely to lead to the most accurate results. And this coincidence is the more remarkable, as it would appear from Dr. Murray not mentioning my labours, that they had not at that time come to his knowledge." Phil. Trans. 1819, part ii. The following table exhibits the composi- tions of the principal mineral waters as well as that of the sea. The reader will find in the Phil. Trans, for 1819 a very valuable disser- tation on sea- water, by Dr. Marcet, of which a good abstract is given in the 2d volume of the Edin. Phil. Journal. This philosopher shows that in Baffin's-Bay, the Mediterranean Sea, and the Tropical Seas, the temperature of the sea diminishes with the depth, accord- ing to the observations of Phipps, Ross, Parry, Sabine, Saussure, Ellis, and Peron ; but that in the Arctic or Greenland Seas, the tempera- ture of the sea increases with the depth. This singular result was first obtained by Mr. Scoresby, in a series of well-conducted expe- riments, and has been confirmed by the later observations of Lieutenants Franklin and Beechy, and Mr. Fisher. I shall prefix the results of the recent ana- lysis by M. Berzelius of the waters of Carls- bad. They are very extraordinary, and he has found many substances not hitherto sus- pected to exist in them. Sulphate of soda 2-58714 Carbonate of soda 1-25200 Muriate of soda 1-04893 Carbonate of lime 0-31219 Fluate of lime 0-00331 Phosphate of lime 0-00019 Carbonate of strontites 0-00097 Carbonate of magnesia 0- 1 822 1 Phosphate of alumina 0-00034 Carbonate of iron 0-00424 Carbonate of manganese a trace *,.' Silica 0.07504 5-4fi656 Ann. de Chim. ct Phys. xxi. 248. IVfl LJ ^3.^3. -N=77 S??? Calcareous, nearly pure. ggrocata EEIfif Sgss5 3*c^ -. i 23 s ~~ Chaly- beate. r-*-s 3*2 111 sf 5 s --^ 3 jq "S . rSedlitz - - a 1 Cheltenham (6) 'g -\ Plombieres (20) j) 1 Dunblane (if,) sp. gr. ^Pitcaithley(i6) Sulphur- ous. Wt>gE KII Ipf ff-g " Acidulous. < ^-^ *?#2 ^if l^IS 2.S > '~*~' Names of the Spring 3S3 ** ** J* I O*3 G3 HI yo Vi ! -4 2 1 mi! ill O w | -* 4^ w 00 >c *c cs Ci eo 228 Sjfvfi illl M '0 gsssg oSSSSS Io| In 3 ^' Sc'e'w ^ fr 09 c OQ O ^ *"B;* Iff ? ca *> tt ll 00 O bo wb S bS 2o55 o oae osg 15 11 C c s: c 5' o" 5" b M S O S bbbb ca P o if! ;hes of g g sss gg| g *. b M b * -1 bb | * 1 E F u en .8- c, W S S ? I '-s o Us - i-J b ^SS s in poo a ' L . L ' ji H < M0f *-. *.Cn M r* cr^ S' Carbon. S: Iff cS'S Erf 5' I g r o, o, ss * 5 l -! E c 1 <^> 10 S en ** 8 r n p c 5 IH&.O S- 5 k S? s u CO 00 oa ^ r ' -*o 5o o> r ^rs 8 Id w r jo w ^J O O o 005 W W i. to o ti CA "-* SON- M ob, jo-^ K ^ a SJ v s :oi | M to ?y )O 90 i o b 9 i c ? g ? e 3 3S2S Oi MOM u yi Sg Sot in in S 2 JO oo ?il c 3 I ?!? p fc g to 8 ? f E TO 3 = ? p'-E -- r . o =9 l< 0> a D li^i n n ra 111 O O O ft Q 1:111:1 8SSS E^SP: i.!i.il CL P-P-0. Hi WAT 804 WAX WATER (OXYGENIZED), or deut- oxide of hydrogen. This interesting com- pound has been lately formed by M. Thenard, and an account of it published in the tenth volume of the Annales de Chimie et de Phy- sique. The deutoxide of barium being dis- solved in water, and sulphuric acid added, the protoxide of barium or barytes falls down, leaving the oxygen combined with the water. It contains, at 32 F. when saturated, twice the quantity of oxygen of common water ; that is to say, a cubic inch absorbs 662 cubic inches = 224-46 gr. forming 476-98 grains, and ac- quires a specific gravity of 1-453. Hence 1-0 in volume becomes apparently 1-3 ; contain- ing 1324 volumes of oxygen ; and 1 volume therefore contains very nearly 1000 volumes. In consequence of this great density, when it is poured into common water, we see it fall down through that liquid like a sort of syrup, though it is very soluble in it. It attacks the epidermis almost instantly, and produces a prickling pain, the duration of which varies, according to the quantity of the liquid ap- plied to the skin. If this quantity be too great, or if the liquid be renewed, the skin itself is attacked and destroyed. When ap- plied to the tongue, it whitens it also, thickens the saliva, and produces in the organs of taste a sensation difficult to express, but one which approaches to that of tartar emetic. Its ac- tion on oxide of silver is exceedingly violent. Every drop of the liquid let fall on the dry oxide produces a real explosion ; and so much heat is evolved, that if the experiment be made in a dark place, there is a very sensible disen- gagement of light. Besides the oxide of silver, there are several other oxides, which act with violence on oxygenated water ; for example, the peroxide of manganese, that of cobalt, the oxides of lead, platinum, gold, iridium, rho- dium, palladium. Several metals in a state of extreme division occasion the same pheno- menon; such as silver, platinum, gold, os- mium, iridium, rhodium, palladium. In all the preceding cases, it is always the oxygen united to the water which is disengaged, and sometimes likewise that of the oxide ; but in others, a portion of the oxygen unites with the metal itself. This is the case when arsenic, molybdenum, tungsten, or selenium is em- ployed. These metals are often acidified with the production of light. The acids render the oxygenated water more stable. Gold in a state of extreme division acts with great force on pure oxygenated water ; yet it has no action on that liquid, if it be mixed with a little sulphuric acid. M. Thenard took pure oxygenated water, and diluted it, so that it contained only 8 times its volume of oxygen. He passed 22 measures of it into a tube filled with mercury. He then introduced a little fibrin, quite white, and re-. cently extracted from blood. The oxygen began instantly to be disengaged from the water ; the mercury in the tube sunk ; at the end of six minutes the water was completely disoxygenated ; for it no longer effervesced with oxide of silver. Having then measured the gas disengaged, he found it, 176 measures 8 X 22, that is to say, as much as the liquid contained. This gas contained neither carbonic acid nor azote. It was pure oxygen. The same fibrin placed in contact with new portions of oxygenated water, acted in the same manner. Urea, albumen, liquid or solid, and gelatin, do not disengage oxygen from water, even very much oxygenated. But the tissue of the lungs cut into thin slices, and well washed ; that of the kidneys and the spleen, drive the oxygen out of the water, with as much facility, at least, as fibrin does. The skin and the veins possess the same property, but in a weaker degree. These results are equally in- teresting and mysterious. For a valuable ap- plication of oxygenated water, see PAINTS. WAVELITJG. Colour grayish - white. Imitative and crystallized, in very oblique four-sided prisms, flatly bevelled on the ex- tremitiesj or truncated on the obtuse lateral edges. Shining, pearly. Fragments wedge- shaped. Translucent As hard as fluor spar. Brittle. Sp. gr. 2-3 to 2-8. Its constituents are, alumina 70, lime 1-4, water 26-2. Davy. It is said to contain also a small quantity of fluoric acid. It occurs in veins along with fluor spar, quartz, tinstone, and copper pyrites in granite, at St. Austle in Cornwall. At Barnstaple in Devonshire, where it was first found by Dr. Wavell, it traverses slate-clay, in the form of small contemporaneous veins. It has been found in rocks of slate-clay, near Loch Humphrey, Dumbartonshire. WAX is an oily concrete matter gathered by bees from plants. Proust says, that the bloom on fruit is real wax ; and that it is wax spread over leaves, which prevents them from being wetted, as on the cabbage-leaf. He like- wise finds it in the fecula cf some vegetables, particularly in that of the small house-leek, in which it abounds. Huber, however, asserts, from his observations, that the wax in bee- hives is an artificial production, made by the bees from honey ; that they cannot procure it, unless they have honey or sugar for the pur. pose; and that raw sugar affords more than honey. It was long considered as a resin, from some properties common to it with resins. Like them, it furnishes an oil and an acid by dis- tillation, and is soluble in all oils; but in several respects it differs sensibly from resins. Like these, wax has not a strong aromatic taste and smell, but a very weak smell, and when pure, no taste. With the heat of boil- ing water no principles are distilled from it ; whereas, with that heat, some essential oil, or at least a spirituous rector, is obtained from every resin. Farther, wax is less- soluble in WAX 805 WEL alcohol. If wax be distilled with a heat greater than that of boiling water, it may be decomposed, but not so easily as resins can. By this distillation, a small quantity of water is first separated from the wax, and then some very volatile and very penetrating acid, ac- companied with a small quantity of a very fluid and very odoriferous oil. As the distil- lation advances, the acid becomes more and more strong, and the oil more and more thick, till its consistence is such that it becomes solid in the receiver, and is then called butter of wax. When the distillation is finished, no- thing remains but a small quantity of coal, which is almost incombustible. Wax cannot be kindled, unless it is pre- viously heated and reduced into vapours ; in which respect it resembles fat oils. The oil of butter of wax may by repeated distillations be attenuated and rendered more and more fluid, because some portion of acid is thereby separated from these substances ; which effect is similar to what happens in the distillation of other oils and oily concretes : but this re- markable effect attends the repeated distilla- tion of oil and butter of wax, that they be- come more and more soluble in alcohol ; and that they never acquire greater consistence by evaporation of their more fluid parts. Boer- haave kept butter of wax in a glass vessel open, or carelessly closed, during twenty years, without acquiring a more solid consistence. It may be remarked, that wax, its butter, and its oil, differ entirely from essential oils and resins in all the above mentioned properties, and that in all these they perfectly resemble sweet oils. Hence Macquer concludes, that wax resembles resins only in being an oil ren- dered concrete by an acid ; but that it differs essentially from these in the kind of the oil, which in resins is of the nature of essential oils, while in wax and in other analogous oily concretions (as butter of milk, butter of cocoa, fat of animals, spermaceti, and myrtle-wax), it is of the nature of mild, unctuous oils, that are not aromatic, and not volatile, and are ob- tained from vegetables by expression. It geems probable, that the acidifying prin- ciple, or oxygen, and not an actual acid, may be the leading cause of the solidity, or low fusibility of wax. Wax is very useful, espe- cially as a better material than any other for candles. Wax may be deprived of its natural yellow disagreeble colour, and be perfectly whitened, by exposure to the united action of air and water, by which method the colour of many substances may be destroyed. The art of bleaching wax consists in in- creasing its surface ; for which purpose it must be melted with a degree of heat not sufficient to alter its quality, in a caldron so disposed, that the melted wax may flow gradually through a pipe at the bottom of the caldron into a large tub filled with water, in which is fitted a large wooden cylinder, that turns con- tinually round its axis, and upon which the melted wax falls. As the surface of this cy- linder is always moistened with cold water, the wax falling upon it does not adhere to it, but quickly becomes solid and flat, and ac- quires the form of ribands. The continual rotation of the cylinder carries off these ribands as fast as they are formed, and distributes them through the tub. When all the wax that is to be whitened is thus formed, it is put upon large frames covered with linen cloth, which are supported about a foot and a half above the ground, in a situation exposed to the air, the dew, and the sun. The thickness of the several ribands thus placed upon the frames ought not to exceed an inch and a half, and they ought to be moved from time to time, that they may all be equally exposed to the action of the air. If the weather be favour- able, the colour will be changed in the space of some days. It is then to be re-melted and formed into ribands, and exposed to the ac- tion of the air as before. These operations are to be repeated till the wax is rendered perfectly white, and then it is to be melted into cakes, or formed into candles. Wax is composed, according to MM. Gay Lussac and Thenard, of Oxygen, 5-544 Hydrogen, 12-672 Carbon, 81-784 100-000 See CERIN. By my analysis wax consists in 100 parts of, Carbon, 80-69 13 atoms 9-75 80-4 Hydrogen, 11-37 11 1-375 11-3 Oxygen, 7-94 1 1-000 8-3 100-00 100-0 Or in other words, of 11 atoms olefiant gas -f- 1 atom carbonic oxide -f- 1 atom carbon. Had the experiment given a very little more hydrogen, we should have had wax as con- sisting of 12 atoms olefiant gas -j- 1 atom carbonic oxide. Phil. Trans, for 1822. Wax is employed for many purposes in several arts. It is also used in medicine as a softening, emolient, and relaxing remedy : but it is only used externally, mixed with other substances. WELD, OR WOALD (reseda luteola, Linn.), is a plant cultivated in Kent, Here- fordshire, and many other parts of this king- dom. The whole of the plant is used for dyeing yellow ; though some assert, that the seeds only afford the colouring matter. Two sorts of Weld are distinguished : the bastard or wild, which grows naturally in the fields ; and the cultivated, the stalks of which are smaller, and not so high. For dyeing, the latter is preferred, it abounding more in colouring matter. The more slender the stalk, the more it is valued. WEJL 806 WIN When the weld is ripe, it is pulled, dried, and made into bundles, in which state it is used. The yellow communicated to wool by weld has little permanency, if the wool be not pre- viously prepared by some mordant For this purpose alum and tartar are used, by means of which this plant gives a very pure yellow, which has the advantage of being permanent. For the boiling, which is conducted in the common way, Hellot directs four ounces of alum to every pound of wool, and only one ounce of tartar: many dyers, however, use half as much tartar as alum. Tartar renders the colour paler, but more lively. For the welding, that is, for the dyeing with weld, the plant is boiled in a fresh bath, enclosing it in a bag of thin linen, and keeping it from rising to the top by means of a heavy wooden cross. Some dyers boil it till it sinks to the bottom of the copper, and then let a cross down upon it : others, when it is boiled, take it out with a rake and throw it away. Hellot directs five or six pounds of weld for every pound of cloth ; but dyers seldom use so much, contenting themselves with three or four pounds, or even much less. To dye silk plain yellow, in general no other ingredient than weld is used. The silk ought to be scoured in the proportion of twenty pounds of soap to the hundred, and afterward alumed and refreshed, that is, washed after the aluming. A bath is prepared with two pounds of weld for each pound of silk, which, after a quarter of an hour's boiling, is to be passed through a sieve or cloth into a vat : when it is of such a temperature as the hand can bear, the silk is put in, and turned till the colour is become uniform : during this operation the weld is boiled a second time in fresh water; about half of the first bath is taken out, and its place supplied by a fresh decoction. This fresh bath may be used a little hotter than the former ; too great a degree of heat, however, must be avoided, that no part of the colour already fixed may be dissolved: it is to be turned as before, and in the mean time a quantity of the ashes of winelees is to be dis- solved in a part of the second decoction ; the silk is to be taken out of the bath, that more or less of this solution may be put in, ac- cording to the shade required. After it has been turned a few times, a hank is wrung with the pin, that it may be seen whether the colour be sufficiently full, and have the proper g-ld cast ; if it should not, a little more of the alkaline solution is added, the effect of which is to give the colour a gold cast, and to render it deeper. In this way the process is to be continued, until the silk has attained the desired shade ; the alkaline solution may also be added along with the second decoction of the weld, always taking care that the bath is not too hot. If we wish to produce yellows with more of a gold or jonquille colour, a quantity of anotta proportioned to the shade required must be added to the bath along with the alkali. A water-colour, called weld-yellow, is much used by paper-hanging manufacturers. This is the colouring matter of weld precipitated with an earthy base. The following is given in the Philosophical Magazine as a method of preparing it very fine: Into a copper vessel put four pounds of fine washed whiting and as much soft water, and boil them together, stirring them with a deal stick, till the whole forms a smooth mixture : then add gradually twelve ounces of powdered alum, still stirring, till the effervescence ceases, and the whole is well mixed. Into another copper put any quantity of weld, with the roots uppermost; pour in soft water enough to cover every part containing seed ; let it boil, but not more than a quarter of an hour ; take out the weld, and set it to drain; and pass the whole of the liquor through flannel. To the hot mixture of earth and water add as much of this decoc- tion as will produce a good colour ; keep it on the fire till it boils, and then pour out into a deal or earthen vessel. The next day the liquor may be decanted, and the colour dried on chalk. WELTER'S TUBE. See LAB OR A. TORY. WERNERITE. Foliated Scapolite. WHEAT FLOUR. See GLUTEN and ZlMOME. WHEAT. See BREAD, GLUTEN, STARCH. WHET SLATE. Colour greenish-gray. Massive. Feebly glimmering. Fracture slaty in the large ; splintery in the small. Frag- ments tabular. Translucent on the edges. Streak grayish- white. Soft in a low degree. Feels rather greasy. Sp. gr. 2.722. It occurs in beds in primitive and transition clay-slate. It is found at Seifersdorf near Freyberg. Very fine varieties are brought from Turkey, called Honestones. It is used for sharpening steel instruments. WHEY. The fluid part of milk which remains after the curd has been separated. See MILK. It contains a saccharine matter, some butter, and a small portion of cheese. WHISKY. Dilute Alcohol, which see, and DISTILLATION. WHITE COPPER. See TUTENAG. WHITE, SPANISH, and WHITE LEAD. See CERUSE. WHITING. Chalk cleared of its grosser impurities, then ground in a mill, and made up into small loaves, is sold under the name of Whiting. WINE. Chemists give the name of wine in general to all liquors that have become spirituous by fermentation. Thus cider, beer, hydromel or mead, and other similar liquors, are wines. WIN 807 WIN The principles and theory of the fermenta- tion which produces these liquors are essen- tially the same. The more general principles we have explained under the article FER- MENTATION. All those nutritive, vegetable, and animal matters which contain sugar ready formed, are susceptible of the spirituous fermentation. Thus wine may be made of all the juices of plants, the sap of trees, the infusions and decoctions of farinaceous vegetables, the milk of frugiverous animals ; and lastly, it may be made of all ripe succulent fruits : but all these substances are not equally proper to be changed into a good and generous wine. As the production of alcohol is the result of the spirituous fermentation, that wine may be considered as essentially the best, which contains most alcohol. But of all substances susceptible of the spirituous fermentation, none is capable of being converted into so good wine,^as the juice of the grapes of France, or of other countries that are nearly in the same latitude, or in the same temperature. The grapes of hotter countries, and even those of the southern provinces of France, do indeed furnish wines that have a more agreeable, that is, more of a saccharine taste ; but these wines, though they are sufficiently strong, are not so spirituous as those of the provinces near the middle of France : at least from these latter wines the best vinegar and brandy are made. As an example, therefore, of spirituous fer- mentation in general, we shall describe the method of making wine from the juice of the grapes of France. This juice, when newly expressed, and before it has begun to ferment, is called must, and in common language sweet wine. It is turbid, has an agreeable and very saccharine taste. It is very laxative ; and when drunk too freely, or by persons disposed to diarrhoeas, it is apt to occasion these disorders. Its con- sistence is somewhat less fluid than that of water, and it becomes almost of a pitchy thickness when dried. When the must is pressed from the grapes, and put into a proper vessel and place, with a temperature between fifty-five and sixty degrees, very sensible effects are produced in it, in a shorter^ or longer time, according to the nature of the liquor, and the exposure of the place. It then swells, and is so rarefied, that it frequently overflows the vessel con- taining it, if this be nearly full. An intestine motion is excited among its parts, accom- panied with a small hissing noise and evident ebullition. The bubbles rise to the surface, and at the same time is disengaged a quantity of carbonic acid of such purity, and so subtle and dangerous, that it is capable of killing instantly men and animals exposed to it in a place where the air is not renewed. The skins, stones, and other grosser matters of the grapes, are buoyed up by the particles of dis- engaged air that ad-here to their surface, are variously agitated, and are raised in form of a scum, or soft and spongy crust, that covers the whole liquor. During the fermentation, this crust is frequently raised, and broken by the air disengaged from the liquor which forces its way through it ; afterward the crust subsides, and becomes entire as before. These effects continue while the fermenta- tion is brisk, and at last gradually cease : then the crust, being no longer supported, falls in pieces to the bottom of the liquor. At this time, if we would have a strong and generous wine, all sensible fermentation must be stopped. This is done by putting the wine into close vessels, and carrying these into a cellar or other cool place. After this first operation, an interval of repose takes place, as is indicated by the cessation of the sensible effects of the spi- rituous fermentation ; and thus enables us to preserve a liquor no less agreeable in its taste, than useful for its reviving and nutritive qualities when drunk moderately. If we examine the wine produced by this first fermentation, we shall find, that it differs entirely and essentially from the juice of grapes before fermentation. Its sweet and saccharine taste is changed into one that is very different, though still agreeable, and somewhat spi- rituous and piquant. It has not the laxative quality of must, but affects the head, and occasions, as is well known, drunkenness. Lastly, if it be distilled, it yields, instead of the insipid water obtained from must by dis- tillation with the heat of boiling water, a volatile, spirituous, and inflammable liquor called spirit of wine, or alcohol. This spirit is consequently a new being, produced by the kind of fermentation called the vinous or spirituous. See ALCOHOL. When any liquor undergoes the spirituous fermentation, all its parts seem not to ferment at the same time, otherwise the fermentation would probably be very quickly completed, and the appearances would be much more striking: hence, in a liquor much disposed to fermentation, this motion is more quick and simultaneous than in another liquor less dis- posed. Experience has shown, that a wine the fermentation of which is very slow and tedious, is never good or very spirituous ; and therefore, when the weather is too cold, the fermentation is usually accelerated by heating the place in which the wine is made. A proposal has been made by a person very intelligent in economical affairs, to apply a greater than the usual heat to accelerate the fermentation of the wine, in those years in which grapes have not been sufficiently ripened, and when the juice is not sufficiently disposed to fermentation. A too hasty and violent fermentation is perhaps also hurtful, from the dissipation und loss of some of the spirit; but of this we are WIN 808 WIN not certain. However, we may distinguish, in the ordinary method of making wines of grapes, two periods in the fermentation, the first of which lasts during the appearance of the sensible effects above mentioned, in which the greatest number of fermentable particles ferment. After this first effort of fermenta- tion, these effects sensibly diminish, and ought to be stopped, for reasons hereafter to be men- tioned. The fermentative motion of the liquors then ceases. The heterogeneous parts that were suspended in the wines by this motion, and render it muddy, are separated and form a sediment called the lees ; after which the wine becomes clear : but though the operation is then considered as finished, and the ferment- ation apparently ceases, it does not really cease ; and it ought to be continued in some degree, if we would have good wine. In this new wine a part of the liquor pro- bably remains, that has not fermented, and which afterward ferments, but so very slowly, that none of the sensible effects produced in the first fermentation are here perceived. The fermentation therefore still continues in the wine, during a longer or shorter time, although in an imperceptible manner ; and this is the second period of the spirituous fermentation, which may be called the imperceptible ferment- ation. We may easily perceive, that the ef- fect of this imperceptible fermentation is the gradual increase of the quantity of alcohol. It has also another effect no less advan- tageous, namely, the separation of the acid salt called tartar from the wine. This matter is therefore a second sediment, that is formed in the wine, and adheres to the sides of the containing vessels. As the taste of tartar is harsh and disagreeable, it is evident that the wine, which by means of the insensible fer- mentation has acquired more alcohol, and has disengaged itself of the greater part of its tar- tar, ought to be much better and more agree- able ; and for this reason chiefly, old wine is universally preferable to new wine. But insensible fermentation can only ripen and meliorate the wine, if the sensible fer- mentation have regularly proceeded, and been stopped in due time. We know certainly, that if a sufficient time have not been allowed for the first period of the fermentation, the un- fermented matter that remains being in too large a quantity, will then ferment in the bot- tles or close vessels in which the wine is put, and will occasion effects so much more sensi- ble, as the first fermentation shall have been sooner interrupted : hence these wines are always turbid, emit bubbles, and sometimes break the bottles, from the large quantity of air disengaged during the fermentation. We have an instance of these effects in the wine of Champagne, and in others of the same kind. The sensible fermentation of these wines is interrupted or rather surpressed, that they may have this sparkling quality. It is well known that these wines make the corks fly out of the bottles ; that they sparkle and froth when they are poured into glasses ; and lastly, that they have a taste much more lively and more piquant than wines that do not sparkle ; but this sparkling quality, and all the effects depending on it, are only caused by a considerable quantity of carbonic acid gas, which is disengaged during the con- fined fermentation that the wine has under- gone in close vessels. This air not having an opportunity of escaping, and of being dissi- pated as fast as it is disengaged, and being interposed betwixt all the parts of the wine, combines in some measure with them, and adheres in the same manner as it does to cer- tain mineral waters, in which it produces nearly the same effects. When this air is entirely disengaged from these wines, they no longer sparkle, they lose their piquancy of taste, be- come mild, and even almost insipid. Such are the qualities that wine acquires in time, when its first fermentation has not con- tinued sufficiently long. These qualities are given purposely to certain kinds of wine to in- dulge taste or caprice ; but such wines are supposed to be unfit for daily use. Wines for daily use ought to have undergone so com- pletely the sensible fermentation, that the suc- ceeding fermentation shall be insensible, or at least exceedingly little perceived. Wine, in which the first fermentation has been too far advanced, is liable to worse inconveniencies than that in which the first fermentation has been too quickly suppressed ; for every fer- mentable liquor is from its nature in a conti- nual intestine motion, more or less strong ac- cording to circumstances, from the first instant of the spirituous fermentation till it is com- pletely purified : hence, from the time of the completion of the spirituous fermentation, or even before, the wine begins to undergo the acid or acetous fermentation. This acid fer- mentation is very slow and insensible, when the wine is included in very close vessels, and in a cool place : but it gradually advances, so that in a certain time the wine, instead of being improved, becomes at last sour. This evil cannot be remedied ; because the ferment- ation may advance, but cannot be reverted. Wine - merchants, therefore, when their wines become sour, can only conceal or ab- sorb this acidity by certain substances, as by alkalis and absorbent earths. But these sub- stances give to wine a dark greenish colour, and a taste which, though not acid, is some- what disagreeable. Besides, calcareous earths accelerate considerably the total destruction and putrefaction of the wine. Oxides of lead, having the property of forming with the acid of vinegar a salt of an agreeable saccharine taste, which does not alter the colour of the wine, and which besides has the advantage of stopping fermentation and putrefaction, might be very well employed to remedy the acidity ' WIN 800 WIN of wine, if lead and all its preparations were not pernicious to health, as they occasion most terrible colics, and even death, when taken in- ternally. We cannot believe that any wine- merchant, knowing the evil consequences of lead, should, for the sake of gain, employ it for the purpose mentioned; but if there be any such persons, they must be considered as the poisoners and murderers of the public. At Alicant, where very sweet wines are made, it is the practice to mix a little lime with the grapes before they are pressed. This, how- ever, can only neutralize the acid already existing in the grape. If wine contain litharge, or any other oxide of lead, it may be discovered by evaporating some pints of it to dryness, and melting the residuum in a crucible, at the bottom of which a small button of lead may be found after the fusion : but an easier and more ex- peditious proof is by pouring into the wine some liquid sulphuret. If. the precipitate occasioned by this addition of the sulphuret be white, or only coloured by the wine, we may know that no lead is contained in it; but if the precipitate be dark coloured, brown, or blackish, we may conclude, that it contains lead or iron. The only substances that cannot absorb or destroy, but cover and render supportable the sharpness of wine, without any inconvenience, are sugar, honey, and other saccharine ali- mentary matters ; but they can succeed only when the wine is very little acid, and when an exceeding small quantity only of these substances is sufficient to produce the desired effect; otherwise the wine would have a sweetish, tart, and not agreeable taste. From what is here said concerning the acescency of wine, we may conclude, that when this accident happens, it cannot by any good method be remedied, and that nothing remains to be done with sour wine but to sell it to vinegar-makers, as all honest wine-mer- chants do. As the must of the grape contains a greater proportion of tartar than our currant and gooseberry juices do, I have been accustomed, for many years, to recommend in my lectures the addition of a small portion of that salt to our must, to make it ferment into a more genuine wine. Dr. M'Culloch has lately pre- scribed the same addition in his popular trea- tise on the art of making wine. The following is Mr. Brande's valuable table of the quantity of spirit in different kinds of wine : Proportion of spirit per cent, by measure. 1. Lissa, 26-47 Ditto v - V *' '24-35 Average, 26-41 2. Raisin wine, *.*'". 26-40 Ditto U H> '3&0 %* . 26-77 Ditto * i- 23-20 Average, 25-12 Proportion of spirit per cent, by measure. 3. Marsala, 26- 3 Ditto 25-5 Average, 25- 9 4. Madeira, 24-42 Ditto 23-93 Ditto (Sirrial) 21-40 Ditto 19-41 Average, 22-27 5. Currant wine, 20-55 6. Sherry, 19-81 Ditto 19-83 Ditto 18-79 Ditto ., '-**l.\ 18-25 Average, 19-17 7. Teneriffe, V,.' 19-79 8. Colares, 19-75 9. Lachryma Christi 19-70 10. Constantia, white, 19-75 11. Ditto, red, 18-92 12. Lisbon, 18-94 13. Malaga (1666) 18-94 14. Bucellas, 18-49 15. Red Madeira, 22-30 Ditto 18-40 Average, 20-35 16. CapeMuschat, - 18-25 17. Cape Madeira, - 22-94 Ditto 20-50 Ditto . - v 18-11 Average, 20-51 18. Grape wine, t 18-11 19. CalcaveUa, 19-20 Ditto 18-10 Average, 18-65 20. Vidonia, 19-25 21. Alba Flora, 17-26 22. Malaga, 17-26 23. White Hermitage, 17-43 24. Rousillon, 19-00 Ditto , i*w ,fti 17-26 Average, 18.13 25. Claret, .-^,- #[ . 17-11 Ditto 16-32 Ditto 14-08 Ditto 12-91 Average, 15-10 26. Malmsey Madeira, 16-40 27. Lunel, 15-52 28. Sheraaz, 15-52 29. Syracuse, 15-28 30. Sauterne, 14-22 31. Burgundy, - 16-60 Ditto 15-22 Ditto 14-53 Ditto 11-95 Average, 14-57 32. Hock, 14-37 Ditto 13-00 Ditto (old in cask) 8-88 Average, 12-08 14-63 34. Barsac, 13-86 35. Tent, 13-30 36. Champagne, (still) - - 13-80 WOA 810 WOL Proportion O f black on the outside, in a close place yellow. Lymeasurl?"' ish > especially if the weather be rainy. The Champagne, (sparkling) . 12-80 dealers in this commodity prefer the first, Ditto (red) 12-56 though it is said the workmen find no con- Ditto (ditto) 11-30 siderable difference between the two. The Average, 12-61 g od balls ar e distinguished by their being 37 Red Hermitage, J2-32 weighty, of a pretty agreeable smell, and, 38. Vin de Grave, ' 13-94 when rubbed, of a violet colour within. Ditto .... 12-80 For the use of the dyer these balls require Average, 13-37 a f art her preparation : they are beaten with 12-79 wooden mallets, on a brick or stone floor, into - 12-32 a gross powder, which is heaped up in the 11-84 middle of the room to the height of four feet, a space being left for passing round the sides. The powder moistened with water ferments, grows hot, and throws out a thick fetid fume. It is shovelled backward and forward, and moistened every day for twelve days; after which it is stirred less frequently, without watering, and at length made into a heap for the dyer. The powder thus prepared gives only brown- ish tinctures of different shades to water, to alcohol, to ammonia, and to fixed alkaline lixivia ; rubbed on paper, it communicates a green stain. On diluting the powder with boiling water, and, after standing for some hours in a close vessel, adding about one- twentieth its weight of lime newly slacked, digesting in a gentle warmth, and stirring the whole together every three or four hours, a new fermentation begins ; a blue froth rises to the surface, and the liquor, though it appears itself of a reddish colour, dyes woollen of a green; which, like the green from indigo, changes in the air to a blue. This is one of the nicest processes in the art of dyeing, and does not well succeed in the way of a small experiment. WOLLASTONITE. A mineral found in small masses, of a brownish tinge exter- nally; transparent and colourless internally, or of a flesh colour; highly crystalline. It seems to be a tabular spar, from the measure- ments by the reflective goniometer of its me- chanical divisions. A more distinctive mineral honour should be appropriated to Dr. Wol- laston. WOOD (OPAL). See OPAL. WOOD (ROCK). The ligniform asbes- tus. WOOD-STONE. A sub-species of horn- stone. WOOD-TIN. See ORES OF TIN. WOOL. See APPENDIX. WOOTZ. The metal extracted from some kind of iron ore in the East Indies, apparently of good quality. It contains more carbon than steel, and less than cast-iron, but from want of skill in the management is far from homo- geneous. Phil. Trans. WORT. See BEER, DISTILLATION, and FERMENTATION. WOLFRAM. See ORES OF TUNG- STEN. 9-88 9-87 9-87 5-21 7-26 7-32 8-88 6-20 5-56 6-87 6-80 4-20 1-28 53-39 53-68 51-60 54-32 39. Frontignac, 40. CoteRotie, 41. Gooseberry wine, y 42. Orange wine, average of six sam- ples made by a London manu- facturer, . . 11-26 43. Tokay, 44. Elder wine, 45. Cider, highest average, Ditto, lowest ditto 46. Perry, average of four samples, 47. Mead, .... 48. Ale (Burton) . ; ,- ..-. Ditto (Edinburgh) . * Ditto (Dorchester) ;-. . !.r .; .> Average, 49. Brown stout, 50. London Porter, (average) ;.> 51. Ditto small beer, (ditto) <; 52. Brandy, . ,v .. 53. Rum, w* 54. Gin, 55. Scotch Whisky, . &.<* S^A 56. Irish ditto t - ,, t -i, : .\*'',. 53-90 WINE (OIL) OF. See OIL or WINE. WITHE RITE. Carbonate of barytes. See HEAVY SPAR. WOAD, Isatis, Glastum, is a plant which grows wild in some parts of France, and on the coast of the Baltic Sea ; the wild woad, and that which is cultivated for the use of the dyers, appear to be the same species of plant. The preparation of woad for dyeing, as prac- tised in France, is minutely described by As- true, in his Memoirs for a Natural History of Languedoc. The plant puts forth at first five or six upright leaves about a foot long and six inches broad : when these hang down- wards, and turn yellow, they are fit for gather- ing ; five crops are gathered in one year. The leaves are carried directly to a mill, much re- sembling the oil or tan-mills, and ground into a smooth paste. If this process were deferred for some time, they would putrefy, and send forth an insupportable stench. The paste is laid in heaps pressed close and smooth, and the blackish crust, which forms on the out- side, reunited if it happen to crack : if this were neglected, little worms would be pro- duced in the cracks, and the woad would lose part of its strength. After lying for fifteen days, the heaps are opened, the crust rubbed and mixed with the inside, and the matter formed into oval balls, which are pressed close and solid in wooden moulds. These are dried upon hurdles: in the sun they turn YTT 311 YTT YANOLITE. Axinite. YEAST. See FERBIENTATION, and BHEAD. YELLOW EARTH. Colour ochre- yellow. Massive. Dull. Fracture slaty or earthy. Streak somewhat shining. Opaque. Soils slightly. Soft. Easily frangible. Ad- heres to the tongue. Feels rather greasy. Sp. gr. 2-24. Before the blowpipe it is con- verted into a black and shining enamel. Its constituents are, silica 92, alumina 2, lime 3, iron 3. Herat - Guillot. It is found at Wehraw in Upper Lusatia, where it is as- sociated with clay and clay-ironstone. When burnt, it is sold by the Dutch as a pigment under the name of English red. It was used as a yellow paint by the ancients. YENITE. Lievrite. YTTRIA. This is a new earth discovered in 1794 by Professor Gadolin, in a stone from Ytterby in Sweden. See GADOLINITE. It may be obtained most readily by fusing the gadolinite with two parts of caustic potash, washing the mass with boiling water, and filtering the liquor, which is of a fine green. This liquor is to be evaporated, till no more oxide of manganese falls down from it in a black powder ; after which the liquid is to be saturated with nitric acid. At the same time digest the sediment, that was not dissolved, in very dilute nitric acid, which will dis- solve the earth with much heat, leaving the silex, and the highly oxided iron, undissolved. Mix the two liquors, evaporate them to dry- ness, redissolve, and filter, which will separate any silex or oxide of iron that may have been left. A few drops of a solution of carbonate of potash will separate any lime that may be present, and a cautious addition of hydrosul- phuret of potash will throw down the oxide of manganese that may have been left ; but if too much be employed, it will throw down the yttria likewise. Lastly, the yttria is to be precipitated by pure ammonia, well washed, and dried. Yttria is perfectly white, when not con- taminated with oxide of manganese, from which it is not easily freed. Its specific gra- vity is 4-842. It has neither taste nor smell. It is infusible alone; but with borax melts into a transparent glass, or opaque white if the borax were in excess. It is insoluble in water, and in caustic fixed alkalis; but it dissolves in carbonate of ammonia, though it requires five or six times as much as glu- cine. It is soluble in most of the acids. The oxalic acid, or oxalate of ammonia, forms pre- cipitates in its solutions perfectly resembling the muriate of silver. Prussiate of potash, crystallized and redissolved in water, throws it down in white grains ; phosphate of soda, in white gelatinous flakes ; infusion of galls, in brown flocks. Some chemists are inclined to consider yttria rather as a metallic than as an earthy substance : their reasons are, its specific gra- vity, its forming coloured salts, and its pro- perty of oxygenizing muriatic acid after it has undergone a long calcination. CreWs Chem. An. Scherer's Journ. Annales de Chimie. When yttria is treated with potassium in the same manner as the other earths, similar results are obtained ; the potassium becomes potash, and the earth gains appearances of metallization; so that it is scarcely to be doubted, says Sir H. Davy, that yttria con- sists of inflammable matter, metallic in its nature, combined with oxygen. According to Klaproth, 55 parts of yttria combine with 18 parts of carbonic acid ; consequently, if it be supposed that the carbonate of yttria consists of one prime proportion of earth and one of acid, its prime equivalent will be 8*403 ; and that of its metallic basis probably 7-4. The salts of yttria have the following general characters: 1. Many of them are insoluble in water. 2. Precipitates are occasioned in those which dissolve, by phosphate of soda, car. bonate of soda, oxalate of ammonia, tartrate of potash, and ferroprussiate of potash. 3. If we except the sweet-tasted soluble sulphate of yttria, the other salts of this earth resemble those with base of lime in their so- lubility. See SALTS. YTTRO-TANTALITE. An ore of TANTALUM. YTTRO-CERITE. Colours reddish and grayish-white, and violet-blue. Massive, and in crusts. Cleavage indistinct. Opaque. Yields to the knife. Scratches fluor. Sp. gr. 3-447- Its constituents are, oxide of cerium 13-15, yttria 14-6, lime 47-77? fluoric acid 24-45. Berzelius. It has hitherto been found only at Finbo, near Fahlun in Sweden, imbedded in quartz or incrusting pyrophy- salite, ZEO 812 ZEO ZAFFRE, or SAFFRE, is the residuum of cobalt, after the sulphur, arsenic, and other volatile matters of this mineral have been ex- pelled by calcination. The zaffre that is commonly sold, and which comes from Saxony, is a mixture of oxide of cobalt with some vitrifiable earth. It is of a gray colour, as all the oxides of cobalt are be- fore vitrification. ZEAGONITE. Abrazite. ZEINE. The zeine of John Gorham is obtained from maize of Indian corn, by in- fusing it in water, filtering and treating with alcohol the matter insoluble in the former liquid, and evaporating the alcoholic solution. We thus obtain a yellow substance having the appearance of wax ; it is soft, ductile, tough, elastic, insipid, nearly void of smell, and denser than water. It affords no ammonia on de- composition by heat ; though it approaches in its nature to gluten. ZEOLITE. The name of a very exten- sive mineral genus, containing the following species: 1. Dodecahedral zeolite or leucite ; 2. hexahedral zeolite or analcime ; 3. rhom- boidal zeolite, chabasite, or chabasie ; 4. py- ramidal zeolite, or cross-stone ; 5. diprismatic zeolite, or laumonite ; 6. prismatic zeolite, or rnesotype, divided into three sub-species, fibrous zeolite, natrolite, and mealy zeolite ; 7- prismatoidal zeolite, or stilbite, compre- hending foliated zeolite, and radiated zeolite ; 8. axifrangible zeolite, or apophyllite. The following belong to this place : 6. Prismatic zeolite or mesotype. 1. Fibrous zeolite, of which there are two kinds ; the acicular or needle zeolite, and com- mon fibrous zeolite. a. Acicular or needle zeolite, the mesotype of Haliy. Colours grayish, yellowish, or red- dish-white. Massive, in distinct concretions, and crystallized. Primitive form, a prism of 91 25'. The following are secondary figures : An acicular rectangular four-sided prism, very flatly acuminated with four planes, set on the lateral planes : sometimes two of the acu- minating planes disappear, when there is formed an acute bevelment, or the prism is sometimes truncated on the edges. Lateral planes longitudinally streaked. Shining, in- clining to pearly. Cleavage twofold. Frac- ture small grained uneven. Fragments splin- tery. Translucent. Refracts double. As hard as apatite. Brittle. Sp. gr. 2.0 to 2.3. It intumesces before the blowpipe, and forms a jelly with acids. It becomes elastic by heat- ing, and retains this property some time after it has cooled. The free extremity of the crys- tal with the acumination, shows positive, the attached end, negative electricity. Its consti- tuents are, silica 50.24, alumina 29.3, lime 9.46, water 10. Vauqudin. It occurs in secondary trap-rocks, as in basalt, greenstone, and amygdaloid. It is found near the village of Old Kilpatrick, Dumbartonshire ; in Ayr- shire and Perthshire, always in trap rocks ; in Iceland and in the Faroe Islands. 6. Common fibrous zeolite. Colour white. Massive, in distinct concretions, and in capil- lary crystals. Glimmering, pearly. Frag- ments splintery. Faintly translucent. Hard- ness as before. Rather brittle. Sp. gr. 2.16 to 2.2. Chemical characters and situations as above. Its constituents are, silica 4J), alumina 27> soda 17, water 9.5. Smithson. 2. Mealy zeolite. Colour white, of various shades. Massive, imitative, in a crust, or in delicate fibrous concretions. Feebly glimmer- ing. Fracture coarse earthy. Opaque. The mass is soft, but the minute parts as hard as the preceding. Sectile. Most easily frangible. Does not adhere to the tongue. Feels meagre. Sometimes so light as nearly to float on water. It intumesces, and gelatinizes as die preceding. Its constituents are, silica 60, alumina 15.6, lime 8, oxide of iron 1.8, loss by exposure to heat, 11.6. Hisinger. It occurs like the others. It is found near Tantallon-castle, in East Lothian, and in the islands of Skye, Mull, and Canna. 7. Prismatoidal zeolite, or stilbite Of this there are two sub-species; the foliated and radiated. 1. Foliated zeolite, the stilbite of Haiiy. Colour white, of various shades. Massive, disseminated, imitative, in distinct granular concretions, and crystallized. Primitive form, a prism of 99 22/. Secondary forms are, a low oblique four-sided prism, variously trun- cated ; a low equiangular six-sided prism ; and an eight-sided prism, from truncation of all the edges of the four-sided prism. Lateral planes transversely streaked. Shining, pearly. Cleavage single. Fracture conchoidal. Trans- lucent. Refracts single. As hard as calca- reous spar. Brittle. Sp. gr. 2 to 2.2. It in- tumesces and phosphoresces before the blow- pipe, but does not form a jelly with acids. Its constituents are, silica 52.6, alumina 17-5, lime 9, water 18.5. Vauquelin. It occurs principally in secondary amygdaloid, either in drusy cavities or in contemporaneous veins. It is also met with in primitive and transition mountains. Very beautiful specimens of the red foliated and radiated zeolites are found at Carbeth in Stirlingshire, and at Loch Hum- phrey in Dumbartonshire ; also in the secon- dary trap rocks of the Hebrides, as of Skye, Canna, and Mull ; and in the north of Ire- land. ZIN 813 ZIN 2. Radiated zeolite. Stilbite of Haiiy. Colours yellowish-white and grayish-white. Massive, in angular pieces, in prismatic and granular concretions, and crystallized in a rec- tangular four-sided prism, variously modified by acuminations. Shining, pearly. Trans- lucent. Hardness and chemical characters as above. Brittle. Sp. gr. 2.14. Its consti- tuents are, silica 40.98, alumina 39.09, lime 10.95, water 16.5. Meyer. Its situations are as the preceding. Jameson. ZERO. The commencement of a scale marked O. Thus we say the zero of Fah- renheit, which is 32 below the melting point of ice ; the zero of the centigrade scale, which coincides with the freezing of water. The absolute zero, is the imaginary point in the scale of temperature, when the whole heat is exhausted ; the term of absolute cold, or pri- vation of caloric. See CALORIC. ZIMOME. The gluten of wheat, treated by alcohol, is reduced to the third part of its bulk. This diminution is owing, not merely to the loss of gliadine, but likewise to that of water. The residue is zimome, which may be obtained pure by boiling it repeatedly in alcohol, or by digesting it in repeated portions of that liquid cold, till it no longer gives out any gliadine. See GLIADINE. Zimome thus purified has the form of small globules, or constitutes a shapeless mass, which is hard, tough, destitute of cohesion, and of an ash-white colour. When washed in water, it recovers part of its viscosity, and be- comes quickly brown, when left in contact of the air. It is specifically heavier than water. Its mode of fermenting is no longer that of gluten ; for when it putrefies it exhales a fetid urinous odour. It dissolves completely in vinegar, and in the mineral acids at a boiling temperature. With caustic potash, it com- bines and forms a kind of soap. When put into lime water, or into the solutions of the alkaline carbonates, it becomes harder and as- sumes a new appearance without dissolving. When thrown upon red-hot coals, it exhales an odour similar to that of burning hair or hoofs, and burns with flame. Zimome is to be found in several parts of vegetables. It produces various kinds of fer- mentation, according to the nature of the sub- stance with which it comes in contact. ZINC is a metal of a bluish-white colour, somewhat brighter than lead ; of considerable hardness, and so malleable as not to be broken with the hammer, though it cannot be much extended in this way. It is very easily ex- tended by the rollers of the flatting mill. Its sp. gr. is from 6.9 to 7-2. In a temperature between 210 and 300 of F., it has so much ductility that it can be drawn into wire, as well as laminated, for which a patent has been obtained by Messrs. Hobson and Sylvester of Sheffield. The zinc thus annealed and wrought retains the malleability it had ac- quired. When broken by bending, its texture ap. pears as if composed of cubical grains. On account of its imperfect malleability, it is dif- ficult to reduce it into small parts by filing or hammering ; but it may be granulated, like the malleable metals, by pouring it, when fused, into cold water; or, if it be heated nearly to melting, it is then sufficiently brittle to be pulverized. It melts long before ignition, at about the 700th degree of Fahrenheit's thermometer; and, soon after it becomes red-hot, it burns with a dazzling white flame, of a bluish or yellowish tinge, and is oxidized with such rapidity, that it flies up in the form of white flowers, called the flowers of zinc, or philoso- phical wool. These are generated so plenti- fully, that the access of air is soon intercepted ; and the combustion ceases, unless the matter be stirred, and a considerable heat kept up. The white oxide of zinc is not volatile, but is driven up merely by the force of the combus- tion. When it is again urged by a strong heat, it becomes converted into a clear yellow glass. If zinc be heated in closed vessels, it rises without decomposition. The oxide of zinc, according to the experi- ments of MM. Gay Lussac and Berzelius, consists of 100 metal -j- 2.44 oxygen ; whence the prime equivalent appears to be 4.1. Sir H. Davy makes it 4.4 from his own and his brother's experiments. When zinc is burned in chlorine, a solid substance is formed of a whitish-gray colour, and semitransparent. This is the only chlo- ride of zinc, as there is only one oxide of the metal. It may likewise be made by heating together zinc filings and corrosive sublimate. It is as soft as wax, fuses at a temperature a little above 212, and rises in the gaseous form at a heat much below ignition. Its taste is intensely acrid, and it corrodes the skin. It acts upon water, and dissolves in it, producing much heat ; and its solution, decomposed by an alkali, affords the white hydrated oxide of zinc. This chloride has been called butter of zinc, and muriate of zinc. From the experi- ments of Dr. John Davy, it consists of nearly equal weights of zinc and chlorine. The equi- valent proportions appear to be, Zinc 4.25 -f- chlorine 4.5. Blende is the native sulphuret of zinc. The two bodies are difficult to combine arti- fically. The salts of zinc possess the follow- ing general characters : 1. They generally yield colourless solutions with water. 2. Ferroprussiate of potash, hydrosulphuret of potash, hydriodate of potash, sulphuretted hydrogen, and alkalis, occasion white precipi- tates. 3. Infusion of galls produces no precipitate. ZIN 814 ZIN The diluted sulphuric acid dissolves zinc: at the same time that the temperature of the solvent is increased, and much hydrogen escapes, an undissolved residue is left, which has been supposed to consist of plumbago. Proust, however, says, that it is a mixture of arsenic, lead, and copper. As the combination of the sulphuric acid and the oxide proceeds, the temperature diminishes, and the sulphate of zinc, which is more soluble in hot than cold water, begins to separate, and disturb the transparency of the fluid. If more water be added, the salt may be obtained in fine prisma- tic four-sided crystals. The white vitriol, or copperas, usually sold, is crystallized hastily, in the same manner as loaf-sugar, which on this account it resembles in appearance ; it is slightly efflorescent. The white oxide of zinc is soluble in the sulphuric acid, and forms the same salt as is afforded by zinc itself. The hydrogen gas that is extricated from water by the action of sulphuric acid carries up with it a portion of zinc, which is appa- rently dissolved in it; but this is deposited spontaneously, at least in part, if not wholly, by standing. It burns with a brighter flame than common hydrogen. Sulphate of zinc is prepared in the large way from some varieties of the native sulphu- ret. The ore is roasted, wetted with water, and exposed to the air. The sulphur attracts oxygen, and is converted into sulphuric acid ; and the metal, being at the same time oxi- dized, combines with the acid. After some time the sulphate is extracted by solution in water ; and the solution being evaporated to dryness, the mass is run into moulds. Thus the white vitriol of the shops generally con- tains a small portion of iron, and sometimes of lead. Sulphurous acid dissolves zinc, and sulphu- retted hydrogen is evolved. The solution, by ex- posure to the air, deposits needly crystals, which, according to Fourcroy and Vauquelin, are sulphuretted sulphite of zinc. By dis- solving oxide of zinc in sulphurous acid, the pure sulphite is obtained. This is soluble, and crystallizable. Diluted nitric acid combines rapidly with zinc, and produces much heat, at the same time that a large quantity of nitrous air flies off. The solution is very caustic, and affords crystals by evaporation and cooling, which slightly detonate upon hot coals, and leave oxide of zinc behind. This salt is deli- quescent. Muriatic acid acts very strongly upon zinc, and disengages much hydrogen ; the solution, when evaporated, does not afford crystals, but becomes gelatinous. By a strong heat it is partly decomposed, a portion of the acid being expelled, and part of die muriate sublimes and condenses in a congeries of prisms. Phosphoric acid dissolves zinc. The phos- phate does not crystallize, but becomes gela- tinous, and may be fused by a strong heat. The concrete phosphoric acid heated with zinc filings is decomposed. Fluoric acid likewise dissolves zinc. The boracic acid digested with zinc becomes milky ; and if a solution of borax be added to a solution of muriate or nitrate of zinc, an in- soluble borate of zinc is thrown down. A solution of carbonic acid in water dis- solves a small quantity of zinc, and more rea- dily its oxide. If the solution be exposed to the air, a thin iridescent pellicle forms on its surface. The acetic acid readily dissolves zinc, and yields by evaporation crystals of acetate of zinc, forming rhomboidal or hexagonal plates. These are not altered by exposure to the air, are soluble in water, and burn with a blue fiame. The succinic acid dissolves zinc with effer- vescence, and the solution yields long, slender, foliated crystals. Zinc is readily dissolved in benzoic acid, and the solution yields needle-shaped crystals, which are soluble both in water and in alco- hol. Heat decomposes them by volatilizing then* acid. The oxalic acid attacks zinc with a violent effervescence, and a white powder soon sub- sides, which is oxalate of zinc. If oxalic acid be dropped into a solution of sulphate, nitrate, or muriate of zinc, the same salt is precipi- tated ; it being scarcely soluble in water, un- less an excess of acid be present. It contains seventy-five per cent, of metal. The tartaric acid likewise dissolves zinc with effervescence, and forms a salt difficult of solu- tion in water. The citric acid attacks zinc with efferves- cence, and small brilliant crystals of citrate of zinc are gradually deposited, which are in- soluble in water. Their taste is styptic and metallic, and they are composed of equal parts of the acid and of oxide of zinc. The malic acid dissolves zinc, and affords beautiful crystals by evaporation. Lactic acid acts upon zinc with efferves- cence, and produces a crystallizable salt. The metallic acids likewise combine with zinc. If arsenic acid be poured on it, an effer- vescence takes place, arsenical hydrogen gas is emitted, and a black powder falls down, which is arsenic in the metallic state, the zinc having deprived a portion of the arsenic, as well as the water, of its oxygen. If one part of zinc filings and two parts of dry arsenic acid be distilled in a retort, a violent detonation takes place when the retort becomes red, occasioned by the sudden absorption of the oxygen of the acid by the zinc. The arseniate of zinc may be precipitated by pouring arsenic acid into the solution of acetate of zinc, or by mixing a solution of an alkaline arseniate with that of sulphate of zinc. It is a white powder, in- soluble in water. By a similar process zinc may be combined ZIN 815 ZIR with the molybdic acid, and with the oxide of tungsten, the tungstic acid of some, with both of which it forms a white insoluble compound ; and with the chromic acid, the result of which compound is equally insoluble, but of an orange-red colour. Zinc likewise forms some triple salts. Thus, if the white oxide of zinc be boiled in a solu- tion of muriate of ammonia, a considerable portion is dissolved ; and though part of the oxide is again deposited as the solution cools, some of it remains combined with the acid and alkali in the solution, and is not precipi table either by pure alkalis or their carbonates. This triple salt does not crystallize. If the acidulous tartrate of potash be boiled in water with zinc filings, a triple compound will be formed, which is very soluble in water, but not easily crystallized. This, like the preceding, cannot be precipitated from its solution either by pure or carbonated alkalis. A triple sulphate of zinc and iron may be formed by mixing together the sulphates of iron and of zinc dissolved in water, or by dis- solving iron and zinc in dilute sulphuric acid. -This salt crystallizes in rhomboids, which nearly resemble the sulphate of zinc in figure, but are of a pale green colour. In taste, and in degree of solubility, it differs little from the sulphate of zinc. It contains a much larger proportion of zinc than of iron. A triple sulphate of zinc and cobalt, as first noticed by Link, may be obtained by digesting zaffre in a solution of sulphate of zinc. On evaporation, large quadrilateral prisms are obtained, which effloresce on exposure to the air. Zinc is precipitated from acids by the soluble earths and the alkalis : the latter re- dissolve the precipitate, if they be added in Zinc decomposes, or alters, the neutral sul- phates in the dry way. When fused with sulphate of potash, it converts that salt into a sulphuret : the zinc at the same time being oxidized, and partly dissolved in the sulphuret. When pulverized zinc is added to fused nitre, or projected together with that salt into a red- hot crucible, a very violent detonation takes place; insomuch that it is necessary for the operator to be careful in using only small quantities, lest the burning matter should be thrown about. The zinc is oxidized, and part of the oxide combines with the alkali, with which it forms a compound soluble in water. Zinc decomposes common salt, and also sal ammoniac, by combining with the muriatic acid. The filings of zinc likewise decompose alum, when boiled in a solution of that salt, probably by combining with its excess of acid. Zinc may be combined with phosphorus, by projecting small pieces of phosphorus on the zinc melted in a crucible, the zinc being covered with a little resin, to prevent its oxidation. Phosphuret of zinc is white, with a shade of bluish- gray, has a metallic lustre, and is a little malleable. When zinc and phosphorus are exposed to heat in a retort, a red sublimate rises, and likewise a bluish sublimate, in needly crystals, with a metallic lustre. If zinc and phosphoric acid be heated together, with or without a little charcoal, needly crystals are sublimed, of a silvery- white colour. All these, according to Pelletier, are phosphuretted oxides of zinc. Most of the metallic combinations of zinc have been already treated of. It forms a brittle compound with antimony; and its effects on manganese, tungsten, and molyb- dena, have not yet been ascertained. An alloy of zinc and iron has been collected by Mr. Herapath in a zinc manufactory at Bristol. It lined the tube leading from the retort. It was hard and brittle, the fracture showing broad facets like zinc, but of a duller gray colour, with surfaces more rough and granular. Its sp. grav. was 7-172. It con- sisted of 92.6 zinc + 7-4 iron in WO. Phil. Magazine, Ixii. 168. Z1RCONIA was first discovered in the jargon of Ceylon by Klaproth, in 1789, and it has since been found hi the jacinth. To obtain ; it, the stone should be calcined and thrown into cold water, to render it friable, and then powdered in an agate mortar. Mix the powder with nine parts of pure potash, and project the mixture by spoonfuls into a red-hot cru- cible, taking care that each portion is fused before another is added. Keep the whole in fusion, with an increased heat, for an hour and. half. When cold, break the crucible, separate its contents, powder and boil in water, to dissolve the alkali. Wash the in- soluble part; dissolve in muriatic acid; heat the solution, that the silex may fall down; and precipitate the zircon by caustic fixed alkali. Or the zircon may be precipitated by carbonate of soda, and the carbonic acid ex- pelled by heat. New Process for preparing pure Zirconia. Powder the zircons very fine, mix them with two parts of pure potash, and heat them red-hot in a silver crucible, for an hour. Treat the substance obtained with distilled water, pour it on a filter, and wash the insoluble part well ; it will be a compound of zirconia, silex, potash, and oxide of iron. Dissolve it in muriatic acid, and evaporate to dryness, to separate the silex. Redissolve the muriates of zirconia and iron in water ; and to separate the zirconia which adheres to the silex, wash it with weak muriatic acid, and add this to the solution. Filter the fluid, and precipitate the zirconia and iron by pure ammonia ; wash the precipitates well, and then treat the hydrates with oxalic acid, boiling them well together, that the acid may act on the iron, retaining it in solution, whilst an insoluble oxalate of zirconia is formed. It is then to be filtered, ZOI 816 200 and the oxalate washed, until no iron can be detected in the water that passes. The earthy oxalate is, when dry, of an opaline colour. After being well washed, it is to be decom- posed by heat in a platinum crucible. Thus obtained, the zirconia is perfectly pure, but is not affected by acids. It must be re- acted on by potash as before, and then washed until the alkali is removed. Afterwards dis- solve it in muriatic acid, and precipitate by ammonia. The hydrate thrown down, when well washed, is perfectly pure, and easily soluble in acids. MM. Dubois and Silveira, Ann. de Chimieet de Phys. xiv. p. 110. Zircon is a fine white powder, without taste or smell, but somewhat harsh to the touch. It is insoluble in water ; yet if slowly dried, it coalesces into a semitransparent yellowish mass, like gum-arabic, which retains one-third its weight of water. It unites with all the acids. It is insoluble in pure alkalis; but the alkaline carbonates dissolve it. Heated with the blowpipe it does not melt, but emits a yellowish phosphoric light Heated in a crucible of charcoal, bedded in charcoal pow- der, placed in a stone crucible, and exposed to a good forge fire for some hours, it undergoes a pasty fusion, which unites its particles into a grey opaque mass, not truly vitreous, but more resembling porcelain. In this state it is sufficiently hard to strike fire with steel, and scratch glass ; and is of the specific gravity of 4-3. There is the same evidence for believing that zirconia is a compound of a metal and oxygen, as that afforded by the action of potassium on the other earths. The alkaline metal, when brought into contact with zirconia ignited to whiteness, is, for the most part, converted into potash ; and dark particles, which, when exa- mined by a magnifying glass, appear metallic in some parts, of a chocolate-brown in others, are found diffused through the potash and the decompounded earth. According to Sir H. Davy, 4-G6 is the prime equivalent of zirconium on the oxygen scale, and 5 -66 that of zirconia. Zirconium has been recently obtained by M. Berzelius by a method exactly similar to that for silicium. See SILICIUM. Zirconium is as black as carbon, does not oxidize in water or in muriatic acid, but nitro-muriatic and fluoric acids dissolve it; the last with the disengagement of hydrogen. At a temperature but slightly elevated it burns with great intensity. It combines with sulphur. Its sulphuret is of a chesnut-brown colour like silicium, and insoluble in muriatic acid or the alkalis* It burns with brilliancy, producing sulphurous acid gas and zirconia. Ann. de Chimieet de-Phys. xxvi. 41. ZOISITE. A sub-species of prismatoidal augite, which is divided into two kinds, the common and friable. 1. Common zoisitc. Colour yellowish- gray. Massive, in granular and prismatic concretions, and crystallized in very oblique four-sided prisms, in which the obtuse lateral edges are often rounded, so that the crystals have a reed-like form. Shining, or glistening and resino-pearly. Cleavage double. Fracture small grained uneven. Feebly translucent. As hard as epidote. Very easily frangible. Sp. gr. 3.3. It is affected by the blowpipe, as epidote. Its constituents are, silica 43, alumina 29, lime 21, oxide of iron 3. Klaproth. At the Saualp in Carinthia, it is found imbedded in a bed of quartz, along with cyanite, garnet, and augite ; or it takes the place of felspar in a granular rock, composed of quartz and mica. It is found in Glen-Elg in Inverness-shire, and in Shetland. 2. Friable zoisitc. Colour reddish-white, which is spotted with pale peach-blossom red. Massive, and in very fine loosely aggregated granular concretions. Feebly glimmering. Fracture intermediate between earthy and splintery. Translucent on the edges. Semi- hard. Brittle. Sp. gr. 3.3. Its constituents are, silica 44, alumina 32, lime 20, oxide of iron 2.5. Klaproth. It occurs imbedded in green talc, at Radelgraben in Carinthia. ZOOPHYTES. Scarcely any chemical experiments have been published on these interesting subjects, if we except the admirable dissertation by Mr. Hatchett, in the Philoso- phical Transactions for 1800. From this dissertation, and from a few experiments of Merat-Guillot, we learn that the hard zoophytes are composed chiefly of three ingredients : 1. An animal substance of the nature of coagulated albumen, varying in consistency ; sometimes being gelatinous and almost liquid, at others of the consistency of cartilage. 2. Carbonate of lime. 3. Phosphate of Hme. In some zoophytes the animal matter is very scanty, and phosphate of lime wanting altogether; in others, the animal matter is abundant, and the earthy salt pure carbonate of lime ; while in others the animal matter is abundant, and the hardening salt a mixture of carbonate of lime and phosphate of lime ; and there is a fourth class almost destitute of earthy salts altogether. Thus, there are four classes of zoophytes : the first resemble por- cellaneous shells ; the second resemble mother- of-pearl shells ; the third resemble crusts ; and the fourth horn. 1. When the madrcpora virginca is im- mersed in diluted nitric acid, it effervesces strongly, and is soon dissolved. A few ge- latinous particles float in the solution, which is otherwise transparent and colourless. Am- monia precipitates nothing ; but its carbonate throws down abundance of carbonate of lime. It is composed, then, of carbonate of lime and a little animal matter. The following zoophytes yield nearly the same results: Madrepora muricata, -- labyrinth ica, zoo 817 ZUR Millepora cerulea, - alcicornis, Tubipora musica. 2. When the madrepora rawed is plunged into weak nitric acid, an effervescence is equally produced ; but after all the soluble part is taken up, there remains a membrane which retains completely the original shape of the madrepore. The substance taken up is pure lime. Hence, this madrepore is composed of carbonate of lime, and a membranaceous sub- stance, which, as in mother-of-pearl shells, retains the figure of the madrepore. The fol- lowing zoophytes yield nearly the same re- sults: Madrepora fascicularis, Millepora cellulosa, . . fascialis, truncata, Iris hippuris. The following substances, analysed by Me- rat-Guillot, belong to this class from their composition, though it is difficult to say what are the species of zoophytes which were ana- lyzed. By red coral, he probably meant the gorgonia nolilis, though that substance is known, from Hatchett's analysis, to contain also some phosphate : While Reel Articulated coral. coral. coralline. Carbonate of lime, 50 53-5 49 Animal matter, 50 46-5 51 100 100-0 100* 3. When the madrepora polymorpha is steeped in weak nitric acid, its shape con- tinues uncharged ; there remaining a tough membranaceous substance of a white colour, and opaque, filled with a transparent jelly. The acid solution yields a slight precipitate of phosphate of lime, when treated with am- monia, and carbonate of ammonia throws down a copious precipitate of carbonate of lime. It is composed, therefore, of animal substance, partly in the state of jelly, partly in that of membrane, and hardened by carbonate of lime, together with a little phosphate of lime. * Merat-Guillot, Ann dc Chim. xxxiv. 71- Flustra foliacea^ treated in the same man- ner, left a finely reticulated membrane, which possessed the properties of coagulated albumen. The solution contained a little phosphate of lime, and yielded abundance of carbonate of lime when treated with the alkaline carbonates. The corallina opuntia, treated in the same manner, yielded the same constituents ; with this difference, that no phosphate of lime could be detected in the fresh coralline, but the solu- tion of burnt coralline yielded traces of it. The iris ochracea exhibits the same phenomena, and is formed of the same constituents. When dissolved in weak nitric acid, its colouring matter falls in the state of a fine red powder, neither soluble in nitric nor muriatic acid, nor changed by them ; whereas the tingeing mat- ter of the tubipora musica is destroyed by these acids. The branches of this iris are di- vided by a series of knots. These knots are cartilaginous bodies connected together by a membraneous coat. Wiihin this coat there is a conical cavity filled with the earthy or coral- line matter ; so that, in the recent state, the branches of the iris are capable of considerable motion, the knots answering the purpose of joints. See CORAL. Mr. Hatchett analyzed many species of sponges, but found them all similar in their composition. The spongia cancdlata, oculata^ infundibuliformis, palmata, and officinalis, may be mentioned as specimens. They con- sist of gelatin, which they gradually give out to water, and a thin brittle membranous sub- stance, which possesses the properties of coa- gulated albumen. ZUMATES. Combinations of the zumic acid with the salifiable bases. ZUMIC ACID. See ACID (ZuMic). ZUNDERERZ. Tinder ore. An ore of silver. ZURLITE. A mineral occurring in rect- angular prisms and in botroidal masses, of an asparagus green colour. It yields to the knife, but emits sparks with steel. Sp. gr. 3-274. Melts with borax into a black glass. It is found on mount Vesuvius witli calcareous APPENDIX. TABLE I. Dr. Wollastoii's Original Numerical Talk of Chemical Equivalent*. Dr Wollaston's numbers represent the weights of the atoms of bodies, oxygen being " ten. 1. Hydrogen 2. Oxygen 3. Water .... 4. Carbon 5. Carbonic acid (-0 oxygen) 6. Sulphur 7. Sulphuric acid (30 oxygen) 8. Phosphorus 9. Phosphoric acid (20 oxygen) 10. Azote or nitrogen 11. Nitric acid (50 oxygen) 12. Muriatic acid, dry 13. Oxymuiiadc acid (10 oxygen) 14. Chlorine 44-10 + T-32 hydro- gen muriatic acid gas 15 Oxalic acid 16. Ammonia 17- Soda IB. Sodium ( above 10 oxygen) 1- ; J. Potash 20. Potassium (above 10 oxygen) 21. Magnesia 22. Lime 23. Calcium (above 10 oxygen) 24. Strontites .... 25 Barytes 26. Iron Black oxide (10 oxygen) Red oxide (15 oxygen) 27. Copper . Black oxide (10 oxygen) 28. Zinc Oxide (10 oxygen) . '*^ 29. Mercury Red oxide (10 oxygen) Black oxide (125-5 mercury) 30. Lead Litharge (10 oxygen) 31. Silver . .- '"'. Oxide (10 oxygen) ' ," ' "" . 32. Sub-carbonate of ammonia Bi-carbonate (27-5 carbonic acid) 33. Sub-carbonate of soda Bi-carbonate (27-5 C. A. + 11-3 water) 34. Subcarbonato of potash 1-32 Bi-carbonate (27-5 C. A. + 10-00 11 -3 water) 11-32 35. Carbonate of lime , 7- t i4 36. 1 -ut 97. ^4 i7 loir! ' / -Ore 20-00 o/. 38. Sulphuric acid, dry . 50-00 39. Do. sp. gr. 1-850 (50 + 11-3 17-40 water) ' 37-40 40. Sulphate of soda (10 water = 17-54 113-2) 67-54 41. Sulphate of potash . 34-10 42. Sulphate of magnesia, dry . 44-10 Do. crystallized (7 water = 79-3) 45-42 43. Sulphate of lime, dry 47-0 Crystalli/ed (2 water = 22-64) 21-5 44. Sulphate of strontites 39-1 45. barytes 29-1 46. coDDcr ( 1 ncid ~\~ 1 59-1 oxide + 5 water) 49-1 47. iron (7 water) . 24-6 48. zinc (do.) 35-46 49. lead ' 25-46 50. Nitric acid, dry 69-00 Nitric acid, sp. gr. 1-50 (2 water 97-00 = 22-64) 34-50 51. Nitrate of soda 44-50 52. potash * , 49-50 53. Iirn.6 40-00 54. . 50-00 KX Imd 41-00 K). 56. Muriate of ammonia .- 51-00 57. soda ; .: 125-50 58. potash . 135-50 Oxymuriate of do. (60 oxygen) 261-00 59. Muriate of lime ^ ' 129-50 60. barytes t 13950 61. lead 135-00 62. silver . 145-00 63. mercury 4900 64. Submuriate of do. (1 acid -f- 1 76-50 66-60 65. oxygen -f- 2 mercury) Phosphate of lead 66. Oxalate of lead ( 105-50 67- Bin-oxalate of potash . 86-00 819 TABLES, exhibiting a colkctive View of all the Frigorific Mixtures contained in Mr. Walker's Publication, 1808. IT. Talk, consisting of Frigorific Mixtures, having the power of generating or creating Cold, without the aid of Ice, sufficient for all useful and philosophical purposes, in any part of the World at any Season. Frigorific Mixtures without Ice. MIXTURES. Thermometer sinks. Deg. of cold produced. Muriate of ammonia Nitrate of potash .'. Water 5 parts 5 16 From -f 50 to -f- 10 40 Muriate of ammonia Nitrate of potash " Sulphate of soda Water 5 parts 5 8 16 From + 50 to + 4 46 Nitrate of ammonia Water 1 part From + 50 to + 4<> 46 Nitrate of ammonia Carbonate of soda Water 1 part 1 1 From + 50 to 7 57 Sulphate of soda Diluted nitric acid 3 parts 2 From + 50 to 3 53 Sulphate of soda Muriate of ammonia Nitrate of potash Diluted nitric acid 6 parts 4 2 4 From + 50 to 10 60 Sulphate of soda Nitrate of ammonia Diluted nitric acid 6 parts 5 4 From + 50 to 14 64 Phosphate of soda Diluted nitric acid 9 parts 4 From + 50 to 12<> 62 Phosphate of soda Nitrate of ammonia Diluted nitric acid 9 parts 6 4 From + 50" to 21 71 Sulphate of soda Muriatic acid 8 parts 5 From + 50" to 50 Sulphate of soda Diluted sulphuric acid 5 parts 4 From + 50 to -f- 3 47 N. B. If the materials are mixed at a warmer temperature than that expressed in the Table, the effect will be proportionably greater ; thus, if the most powerful of these mix- tures be made when the air is -f- 85, it will sink the thermometer to + 2. Ill TABLE consisting ofFrigorific Mixtures, composed of Ice, with chemical Salts and Acids. Frigorific Mixtures with Ice. MIXTURES. Thermometer sinks. Deg. of cold produced. Snow, or pounded ice 2 parts Muriate of soda 1 to 5 * Snow, or pounded ice 5 parts Muriate of soda * 2 Muriate of ammonia 1 to 12 * Snow, or pounded ice 24 parts Muriate of soda 1 Muriate of ammonia 5 Nitrate of potash 5 f to 18 * Snow, or pounded ice 12 parts Muriate of soda 5 to 25 * 820 TABLE III. Continued. Frigorific Mixtures with Ice. MIXTURES. Thermometer sinks. Deg. of cold produced. Snow Diluted sulphuric acid 3 parts 2 From +32 to 23 55 Snow Muriatic acid 8 parts 5 From + 32 to 27 59 Snow Diluted nitric acid 7 parts 4 From + 32 to 30 62 Snow Muriate of lime 4 parts 5 From -f- 32 to 40 72 Snow Cryst. muriate of lime 2 parts 3 From + 32 to 50 82 Snow Potash .... 3 parts 4 From -f 32 to 51 83 N. B. The reason for the omissions in the last column of this Table, is, the thermometer sinking in these mixtures to the degree mentioned in the preceding column, and never lower, whatever may be the temperature of the materials at mixing. IV. TABLE consisting of Frigorific Mixtures selected from the foregoing Tables, and combined so an to increase or extend Cold to the extreme st Degrees. Combinations of Frigorific Mixtures. MIXTURES. Thermometer sinks. Deg. of cold produced. Phosphate of soda Nitrate of ammonia Diluted nitric acid 5 parts o 4 From to 34 34 Phosphate of soda Nitrate of ammonia ,^. Diluted mixed acids 3 parts 2 4 From 34 to 50 16 Snow Diluted nitric acid 3 parts 2 From to 46 46 Snow Diluted sulphuric acid Diluted nitric acid 8 parts 3 3 From 10 to 56 46 Snow Diluted sulphuric acid 1 part From 20 to 60 40 Snow Muriate of lime . Jj?f 3 parts 4 From -f 20 to 48 68 Snow Muriate of lime 3 parts 4 From-}- 10 to 54 64 Snow Muriate of lime - - ; -- 2 parts ' O From 15 to 68 53 Snow Cryst. muriate of lime 1 part 2 From to 66 66 Snow Cryst. muriate of lime lpa From 40 to 73 33 5M1OW Diluted sulphuric acid 8 parts 10 From 68<> to 91 23 N. C. The materials in the first column are to be cooled, previously to mixing, to the temperature req uired, by mixtures taken from either of the preceding tables. 821 V. TABLE of Capacities of different Substances for Caloric. In this Table, the authorities are marked by the initials of the respective authors' names, C.Crawford: K. Kirwan: Ir. Irvine: G. Gadolin: L.Lavoisier: W. Wilcke: M. Meyer. GASES. I. Hydrogen gas 21-4000 C. 4. Aqueous vapour 1-5500 C. 2. Oxygen gas ... 4-7490 5. Carbonic acid gas 1-6454 _ 3. Atmospheric air 1-7900 6. Nitrogen gas _. r - 7936 LIQUIDS. 7- Solution of carbonate of am- 33. Solution of sulphate of iron monia - * . /* 1-8510 K. in 2-5 of water 7340 K. a Solution of brown sugar l-086'O 34. Solution of sulphate of soda !>. Alcohol (15-44) - L0860 in 2-9 of water - 7280 _ 10. Arterial blood -;ir*"~" " 1-0300 C. 35. Olive oil - 7100 __ 11. Water . . -..<*-'< 1-0000 36. Water of ammonia, sp. gr. 12. Cow's milk ... 9999 C. 0-997 7080 _ Ift Sulphuret of ammonia - -9940 K. 37. Muriatic acid, sp. gr. 1-122 6800 __ 14. Solution of muriate of soda, 38. Sulphuric acid, 4 parts with 1 in 10 of water 9360 G. 5 of water - 6631 L. 1*. Alcohol (9-44) - 9300 Ir. 39. Nitric acid, sp. gr. 1-29895 -6613 10. Sulphuric acid, diluted with 40. Solution of alum in 4-45 of 10 of water - -9250 G. water ... 6490 M. 17- Solution of muriate of soda 41. Mixture of nitric acid with in 6*4 of water -9050 G. lime, 9 to 1 6189 L. IK. Venous blood - - r -8928 C. 42. Sulphuric acid, with an equal n. Sulphuric acid, with 5 parts weight of water 6050 G. of water - -8760 G. 43. Sulphuric acid, 4 parts with 20. Solution of muriate of soda in 3 of water ... 6031 I/. 5 of water -8680 G. 44. Alcohol (9-15) -6021 C. 21. Nitric acid (39) -8440 K. 45. Nitrous acid, sp. gr. 1-354 - 5760 K. 22. Solution of sulphate of mag- 46. Linseed oil 5280 _. nesia in 2 of water 8440 47- Spermaceti oil (53) 5000 C. 2:*. Solution of muriate of soda 48. Sulphuric acid, with ^ of in 8 of water -8320 water ... 5000 G. 24. Solution of muriate of soda 49. Oil of turpentine (52) 4720 K. in 3-33 of water 8200 G. 50. Sulphuric acid, with ^ of 25. Solution of nitrate of potash water - 4420 G. in 8 of water 8167 L. 51. Sulphuric acid (31-55,56,57) 4290 C. 20. Solution of muriate of soda 52. Oil of turpentine (49) .4000 Ir. in 2-8 of water - -8020 G. 53. Spermaceti oil (47) 3990 K. 27. Solution of muriate of am- 54. Red wine vinegar 3870 monia in 1 -5 of water -7980 K. 55. Sulphuric acid, concentrated 28, Solution of muriate of soda and colourless (31) -3390 G. saturated, or in 2-69 of 56. Sulphuric acid, sp. gr. water - . : vt s -vffl ! 7930 G. 1-87058 3345 L. 2J). Solution of supertartrate of 57. Sulphuric acid (31-51) - -3330 Ir. 8ft. potash in 237-3 of water - Solution of carbonate of potash -7650 -7590 K. 58. 59. Spermaceti melted Quicksilver, sp. gr. 13-30 3200 0330 K. 31 Colourless sulphuric acid 60. Quicksilver - 0290 L. (51-55,56,57) - -7580 61. . - - -0290 W. 83. Sulphuric acid, with 2 parts 62. - - v '."* -0280 Ir. of water 7490 G. SOLIDS. 63. Ice -9000 K. 68. Scotch fir wood - 6500 M. HA Ir. 69. Lime tree wood - - 2600 O-4. nr>. Oxhide with the hair - -7870 C. 70. Spruce fir wood - -6000 *;t;. Sheep's lungs -7690 71. Pitch pine wood -5800 7- Beef of an ox - - -' - 7400 72. Apple tree wood -5700 822 73- Alderwood - - - -5300 M. 74. Sessile-leaved oak - -5100 75. Ash wood - -MOO 76. Pear tree wood - - -5000 77- Rice 5060 C. 78. Horse-beans [K> - '5020 79. Dust of the pine tree - -5000 80. Pease 4920 81. Beech 4900 M. 82. Hornbean wood - - -4800 83. Birch wood - - - -4800 84. Wheat - - - -4770 G 85. Elm 4700 M. 86. White wax - - - -4500 G. 87. Pedunculated oak wood - -4500 M. 88. Prune tree ... -4400 89. Ebony wood - - - -4300 90. Quicklime, with water, in the proportion of 16 to 9 -4391 L. 91. Barley - - - -4210 C. 92. Oats 4160 93. Charcoal of birch wood (99) -3950 G. 94. Carbonate of magnesia - -3790 95. Prussian blue - - -3300 96. Quicklime, saturated with water and dried - - - -2800 G. 97- Pit coal - . - .2777 C. 98. Artificial gypsum - - -2640 G. 99. Charcoal (93) . - -2631 C. 100. Chalk (108) - - . -2564 101. Rust of iron ;f.^ .: .2500 102. White clay - .-* :. -2410 G. 103. White oxide of antimony washed - - - -2272 C. 104. Oxide of copper U : -v ; i -2272 105. Quicklime (107) -V* '- - -2239 106. Muriate of soda in crystals -2260 G. 107- Quicklime (105) - - -2168 L. 108. Chalk (100) - ;-. : ' -2070 G. 109. Crown glass - - -2000 Ir. 110. Agate, sp. gr. 2-648 - -1950 W. 111. Earthen ware - - -1950 K. 112. Crystal glass without lead - -1929 L. 113. Cinders - - - -1923 C. 114. Sulphur . . . .1890 Ir. 115. Ashes of cinders - - -1855 C. 116. White glass, sp. gr. 2-386 -1870 W. 117. White clay burnt - - -1850 G. 118. Black lead - - - -1830 G. 119. Sulphur - - - -1830 K. 120. Oxide of antimony, nearly free of air - - - -1666 C. 121. Rust of iron, ditto, ditto -1666 122. Ashes of elm wood - -1402 123. Iron (125.127,128.132) - -1450 Ir. 124. Oxide of zinc, nearly freed from air - - - -1369 C. 125. White cast iron - : . .1320 G. 126. White oxide of arsenic - -1260 127. Iron (123.132) - - -1269 C. 128. Iron, sp. gr. 7.876 - -1260 W. 129. Cast iron abounding in plumbago - -1240 G. 130. Hardened steel - - -1230 131. Steel softened by fire - -1200 132. Soft bar iron, sp. gr. 7-724 -1190 133. Brass, sp. gr. 8-356 (135) -1160 W. 134. Copper, sp. gr. 8-785 (136) -1140 135. Brass (133) - - -1123 C. 136. Copper (134) - - - -1111 137. Sheet iron ... -1099 L. 138. Zinc, sp. gr. 7-154 (143) - 4020 W. 139. White oxide of tin, nearly free of air - - - -990 C. 140. Cast pure copper, heated be- tween charcoal, and cooled slowly, sp. gr. 7-907 - -990 G. 141. Hammered copper, sp. gr. 9-150 - - - -970 G. 142. Oxide of tin - - - -960 K. 143. Zinc (138) - - - -943 C. 144. Ashes of charcoal - . -909 145. Sublimated arsenic - -840 G. 146. Silver, sp. gr. 10-001 - -820 W. 147- Tin (152) - - - -704 C. 148. Yellow oxide of lead - - .680 149. White lead ... -670 G. 150. Antimony ... .645 151. Antimony, sp. gr. 6-107 -630 W. 152. Tin, sp. gr. 7-380 (147) - -600 153. Red oxide of lead - - -590 G. 154. Gold, sp. gr. 19-04 - - -500 W. 155. Vitrified oxide of lead - .590 G. 156. Bismuth, sp. gr. 9-861 - -430 W. 157. Lead, sp. gr. 11-45 - -420 158. .... .352 C. The above capacities of the gases are all erroneous ; and those of the other bodies are pro- bably more or less incorrect. See CALORIC. VI. Correspondence of the Thermometers of Fahrenheit and Reaumur, and that of Celsius, or the Centigrade Thermometer of the modern French Chemists. Kaiir. eaum. Celsi. 'ahr. eauiri . Celsi. 'ahr. eaum. Celsi. ahr. rtt-.ii.ni. Uelsi. 212 ttO 00- 148 51 5 64-4 555 23-5 29-4 22 4-4 55 211 79-5 99-4 147 51-1 63-8 84 23 1 28-8 21 48 6-1 210 79-1 98-8 146 50-6 63-3 83 22-6 283 '20 5-3 6-6 209 78-6 98-3 145 50-2 62-7 82 22-2 27-7 19 57 7-2 208 78-2 97-7 144 49-7 62-2 81 21-7 27-2 18 6-2 7-7 207 77-7 97-2 143 49-3 61-6 80 21-3 26-6 17 6.6 8-3 206 77-3 96-6 142 48-8 61-1 79 20-8 26.1 16 7-1 8-8 205 76-8 96-1 141 48.4 60.5 78 20-4 25.5 15 7-5 94 204 76-4 95-5 140 48 60 77 20 25 14 8 10 203 76 95 139 47-5 59-4 76 195 24-4 13 8-4 10-5 202 75-5 944 138 41-1 58-8 75 19-1 23-8 12 8-8 11-1 201 75-1 93-8 137 46-6 58-3 74 18-6 233 11 9-3 11-6 200 74-6 93-3 136 46-2 57-7 73 18-2 22-7 10 9-7 122 199 74-2 92-7 135 457 57-2 72 17-7 22-2 9 10-2 12-7 198 73-7 92-2 134 45-3 56-6 71 17-3 2L6 8 10-6 133 197 73-3 91-6 133 44-8 56-1 70 16-8 21.1 7 1M 13-8 196 72-8 9M 132 44-4 55-5 69 16-4 20-5 6 11 5 14-4 195 72-4 90.5 131 44 55 68 16 20 5 12 15 194 72 90 130 43-5 54-4 67 15-5 19-4 4 12-4 155 193 71-5 89-4 129 43-1 53-8 66 15-1 18-8 3 12-8 16-1 192 7M 88-8 128 42-6 53-3 65 14-6 18-3 2 13-3 16-6 191 70-6 88-3 127 42-2 52-7 64 14-2 17-7 1 13-7 17-2 190 70-2 87-7 126 41-7 52-2 63 13-7 17-2 14-2 17-7 189 69-7 87-2 125 41-3 51.6 62 133 16-6 1 14-6 18-3 188 68-3 86-6 124 40-8 51-1 61 12-8 16.1 2 15-1 18-8 187 68-8 86-1 123 40-4 50.5 60 12-4 15.5 3 15-5 19-4 186 68-4 85-5 122 40 50 59 12 15 4 16 20 185 68 85 121 39-5 49-4 58 11-5 14-4 5 164 205 184 67-5 84-4 120 39-1 48-8 57 1M 13-8 6 16-8 21-1 183 67-1 83-8 119 38-6 48-3 56 10-6 133 7 17-3 21.6 182 66-6 83-3 118 38-2 47-7 55 102 12-7 8 177 22-2 181 66-2 82-7 117 37-7 47-2 54 9-7 12.2 9 18-2 22-7 180 65-7 82-2 116 37-3 46-6 53 9-3 11.6 10 186 23-3 179 65-3 81-6 115 368 46-1 52 8-8 11.1 11 19-1 23-8 178 64-8 81-1 114 36-4 45-5 51 8-4 10-5 12 195 24-4 177 64-4 80-5 113 36 45 50 8 10 13 20 25 176 64 80 112 35-5 44-4 49 7-5 9-4 14 20-4 25-5 175 63-5 79-4 111 35-1 43-8 48 7-1 8-8 15 20-8 26.1 174 63-1 78-8 110 34-6 433 47 6-6 83 16 21-3 26-6 173 62-6 78-3 109 34-2 42-7 46 62 7-7 17 21-7 27-2 172 62-2 77-7 108 33-7 42-2 45 5-7 7-2 18 222 27-7 171 61-7 77-2 107 33-3 41-6 44 5-3 6-6 19 22-6 28-3 170 61-3 76-6 106 32-8 41-1 43 4-8 6.1 20 23-1 28-8 169 60-8 76-1 105 32-4 40-5 42 4-4 5-5 21 23-5 29-4 168 60-4 75.5 104 32 40 41 4 5 22 24 30 167 60 75 103 31-5 394 40 35 4-4 23 24-4 305 166 59-5 74-4 102 3M 38-8 39 3-1 3-8 24 24.8 3M 165 59-1 73-8 101 30-6 38-3 38 2-6 3-3 25 25-3 31-6 164 58-6 73-3 100 30-2 37-7 37 22 2-7 26 25.7 32-2 163 58-2 72-7 99 297 37-2 36 1-7 2-2 27 26-2 327 162 57-7 72-2 98 29-3 36-6 35 1-3 1.6 28 26-6 33-3 161 57-3 71-6 97 28-8 36-1 34 0-8 1.1 29 27-1 33-8 160 56-8 71-1 96 28-4 35-5 33 0-4 0-5 30 27-5 34-4 159 56-4 70-5 95 28-0 35 32 31 28-4 35 158 56 70 94 275 34-4 31 0-4 0-5 32 28 35-5 157 55-5 69-4 93 27-1 33-8 30 0-8 1-1 33 28-8 36 I 156 55-1 68-8 92 26-6 33-3 29 1-3 1-6 34 29-3 366 155 54-6 68-3 91 262 32-7 28 1-7 2-2 35 29-7 37-2 154 54-2 67-7 90 25-7 32-2 27 22 2-7 36 302 377 153 53-7 67-2 89 25-3 31-6 26 2-6 3.3 37 30-6 ;)8-3^ 152 53-3 66-6 88 248 31-1 25 3-1 3-8 38 31-1 38-8 151 52-8 66-1 87 244 30-5 24 3-5 44 39 31-5 39-4 150 52-4 65-5 86 24 30 23 4 *. 40 32 40 149 52 65 TABLE VII Of the Elastic Force of the Vapour of Water in incites of Mercury, by i)n. URE. Temp. Fores. Temp. Force. Temp- Force. Temp. Force. Temp. Force. Temp. Force. 24 0-170 115 2-820 195 21-100 242 53-600 270o 86-300 295-6 130400 32 0-200 120 3-300 200 23 600 245 56340 271-2 88-000 295 129-000 40 0-250 125 3-830 205 25-900 245-8 57-100 273-7 91-200 297-1 133900 50 0-360 130 4-366 210 28-880 248-5 60-400 275 93-480 298-8 137-400 55 0-410 135 5-070 212 30-000 250 61.900 275-7 94-600 300 139-700 CO 0516 140 5-770 216-6 33-400 251-6 63500 277-9 97-800 300-6 140-900 05 0-630 145 6-600 220 35-540 254-5 66-700 279-5 101-600 302 144-300 70 0-726 150 7-530 221-6 36-700 255 67-250 280 101.900 3038 147.700 75 0-860 155 8-500 225 39-110 257-5 69-800 281-8 104-400 305 150-560 80 1-010 160 9-600 2263 40.100 260 72.300 2838 107-700 306-8 154.400 85 1-170 165 10.800 230 43-109 260-4 72.800 285-2 112-200 308 157.700 90 1-360 170 12.050 230-5 43-500 262-8 75-900 287-2 114.800 310 161-300 95 1-640 175 13-550 234-5 46-800 204-9 77-900 289 118-200 311-4 164.800 100 l-86'O 180 15.160 235 47-220 265 70.040 290 120.150 312 167-000 105 2-100 185 16-900 238-5 50-300 267 81.900 2923 123100 Another experim. 110 2-456 190 19-000 240 51-700 269 84.900 294 126-700 312<> ! 165-5 TABLE VIII Of the Elastic Forces of the Vapours of Alcohol, Ether, Oil of Turpentine, and Petroleum, or Naphtha, by DR. URE. Ether. Aboh.sp.gr. 0.813 .\lcoh.sp.gr.0.8l3. Petroleum. Temp. Force of Vapour. Temp. Force of Vapour. Temp. Force of Vapour. Temp. Force of Vapour. 34o 6-20 32o 0-40 193-30 46-60 316 30-00 44 8-10 40 0-56 196-3 50-10 320 31-70 54 10-30 45 0-70 200 53-00 325 34-00 64 13-00 50 0-86 206 60-10 330 36-40 74 Id- 10 55 1.00 210 65-00 335 38-90 84 20-00 60 1-23 , 214 69-30 340 41-60 94 24.70 65 1-49 216 72-20 345 44-10 104 30.00 70 1-76 220 78-50 350 46-86 75 2-10 225 87-50 355 50-20 2d Ether. 80 245 230 94-10 360 53-30 85 2-93 232 97-10 365 56-90 105 30-00 90 3-40 236 103-60 370 60-70 110 3254 95 3-90 238 106-90 372 61-90 115 35-90 100 4-50 240 111-24 375 64-00 120 125 39-47 43-24 106 110 620 6-00 244 247 11820 122-10 Oil of Turpentine. 130 47-14 115 7-10 248 126-10 Force of 135 51-90 K/ Cll\ 120 1 OR 8-10 249-7 O ~ A 131-40 1 OO OA Temp. Vapour. 140 145 oo-yu 62-10 Uo 130 9-25 10-60 /oU 252 loz-oO 138-60 304" 3000 150 67-60 135 12-15 254-3 143-70 307-6 32-60 155 73-60 140 13-90 258-6 151-60 310 33-50 100 80-30 146 15-95 260 155-20 315 35-20 166 86-40 150 18-00 262 161-40 320 3706 170 92-80 155 20-30 264 166-10 322 37-80 175 99-10 160 22-60 326 40-20 180 108-30 16ft 25-40 330 42.10 185 1KMO 170 28.30 336 45-00 190 124-80 173 30-00 340 47.30 195 133-70 178-3 33-50 343 49-40 200 14280 180 34-73 347 51-70 205 151.30 182-3 36-40 350 53-80 210 166-00 185-3 39.90- 354 56-60 190 43.20 357 58-70 360 60-80 362 62-40 825 TABLE IX. New French Weights and Measures (computed by DR. URE). 1. Measures of Length: the Metre being at 32, and the Foot at 62. Millimetre Centimetre Decimetre = English inches. 03937 39371 3-93708 Metre * = 39-37079 Mil. Fur. Yds. Feet. In. x Decametre 393-70790 = 10 2 9-7 Hecatometre 3937-07900 = o o 109 1 1-078 Kilometre 39370-79000 = 4 213 1 10-3 Myriometre 393707-90000 = 6 1 156 9-17 2. Measures of Capacity : Cubic inch contains 252-5 Imperial grains of water, at 62. i Cubic inches. Millilkre 0-06112 Centilitre Decilitre 0-61120 6-11208 Imperial. Gallons. Pints. Litre 61-12079 = 1-76377 Decalitre - 611-20792 = 2 1-4464 Hecatolitre 6112-07920 = 22 0-2640 Kilolitre 61120-79208 220-47 Myriolitre *= 611207-92080 = 220471 3. Measures of Weight. English grains. Milligramme -0154 Centigramme = -1543 Decigramme Gramme 1-5433 15-4330 Avoirdupois. Pound. Decagramme = 154-3300 0.022 Hecatogramme = 1543-3300 0-220 Kilogramme 15433-0000 2-204 Myriogramme 154330-0000 .= 22-047 TABLE X. Correspondence of English Weights and Measures "with those used in France before the Revolution. 1. Weights. The Paris pound, poids de marc of Charlemagne, contains 9216 Paris grains; it is divided into 16 ounces, each ounce into 8 gros, and each gros into 72 grains. It is equal to 7561 English troy grains. The English troy pound of 12 ounces contains 5760 English troy grains, and is equal to 7021 Paris grains. The English avoirdupois pound of 16 ounces contains 7000 English troy grams, and is equal to 8532-5 Paris grains. To reduce Paris grains to English troy grains, divide by } 1-2189 English troy grains to Paris grains, multiply by $ To reduce Paris ounces to English troy, divide by } 1-015734 English troy ounces to Paris, multiply by j 2. Long and Cubical Measures. To reduce Paris running feet, or inches, into English, multiply by ) 1.955977 English running feet, or inches, into Paris, divide by $ To reduce Paris cubic feet, or inches, to English, multiply by ) 1-21 1^78 English cubic feet, or inches, to Paris, divide by $ * Recently determined by Captain Kater to be 39-37079 inches. (Phil. Trans. 1818, p. 109). TABLE XI. Correspondence letwecn English and other Foreign Weights and Measures. I. English Weights and Measures. Troy Weight. Pound. Ounces. Drms. Scruples. Grains. Grammes. 1 = 12 = 96 288 = 5760 = 372-96 1 = 8 = 24 = 480 = 31-08 1 = 3 = 60 = 3-885 1 = 20 = 1-295 1 - 0-06475 Avoirdupois Weight. Pound. Ounces. Drms. Grains. Grammes. 1 = 16 = 256 = 7000- = 453 25 1 = 16 = 437-5 = 28-328 1 = 27-34375= 1-7705 Measures. Gal. Pints. Ounces. Drms. Cubic. Inch. Litres. 1 = 8 = 128 = 1024 = = 3.78515 1 = 16 = 128 = [28-875 = 0-47398 1 = 8 = 1-8047 - 0-02957 1 = 0-2256 = 0-00396 N. B. The English ale gallon contains 282 cubical inches. The wine gallon contains 58176 Troy grains; and the wine pint 7272 Troy grains. II. German. 71 Ibs. or grs. English troy = 74 Ibs. or grs. German apothecaries' weight. 1 oz. Nuremberg, medic, weight = 7 dr. 2 sc. 9 gr. English. 1 mark Cologne . = 7 oz. 2 dwt. 4 gr. English troy. III. Dutch. 1 Ib. Dutch = 1 Ib. 3 oz. 16 dwt. 7 gr. English troy. 787^ Ibs. Dutch = 1038 Ibs. English troy. IV. Swedish Weights and Measures, used by Bergmann and Scliecle. The Swedish pound, which is divided like the English apothecary or troy pound, weighs 6556 grs. troy. The kahne of pure water, according to Bergmann, weighs 42250 Swedish grains, and occupies 100 Swedish cubical inches. Hence the kanne of pure water weighs 48088-719444 English troy grains, or is equal to 189.9413 English cubic inches ; and the Swedish longitu- dinal inch is equal to 1 -238435 English longitudinal inches. By Everard's experiment, and the proportions of the English and French foot, as established by the Royal Society and French Academy of Sciences, the following numbers are ascer- tained: Paris grains in a Paris cube foot of water at 55 F. = 645511 English grains in a Paris cube foot of water = 529922 Paris grains in an English cube foot of water = 533247 English grains in an English cube foot of water - = 437489-4 English grains in an English cube inch of water = 253-175 As a cubic foot of water weighs very nearly 1000 ounces avoirdupois, the specific gra- vities of bodies express the ounces in a cubic foot of them, the density of water being called 1000. 827 TABLE XII Of the Solubility of some Solids m Water. NAMES OF SALTS. Solubility in 10 Parts Water. At 60 At 212" Acids. TiO 1UU 0-208 2 Camphoric : .25 50 83 + 100 strontites - ..., Insoluble Camphorate of ammonia . * . barytes ^'-4 1 0-16 33 lime 0-5 potash 33 + 33 Citrate of soda / ~ . 60 lime .... Insoluble Chlorate of barytes - ... 25 + 25 mercury * potash soda 25 6 35 40 + 35 Muriate of ammonia 33 100 barytes 20 + 20 lead .... 4-5 lime 200 magnesia 100 en mercury on potash .... 33 8^8 NAMES OF SALTS. Solubility in 100 Parts Water. At 60 At 212 Muriate of soda 35-42 36-16 strontites 150 Unlimited Nitrate of ammonia H|i 50 200 barytes 4 8 25 lime - I ; *.* ^ 400 magnesia 100 + 100 potash 14-25 100 soda Jf . 33 + 100 strontites 100 200 Oxalate of strontites O.-BTT Phosphate of ammonia 25 + 25 barytes limes magnesia /- < 6-6 potash Very soluble soda - ._ 25 50 strontites i"-" '.'*'' Phosphite of ammonia 50 + 50 barytes 0-4 potash 33 + 33 Sulphate of ammonia 50 100 barytes 0-002 copper . > 25 50 iron 50 + 100 lead M' ;f - p. i . lime '*''. 0-2 0-22 magnesia . ; '^ 100 133 potash 6-25 20 soda 37 125 strontites 002 Sulphite of ammonia 100 lime . 0125 magnesia * ' '"' 4 'C 5 potash 100 soda . **f' 25 100 Saccholactate of potash * '' 12 soda fal 20 Sub-borate of soda (borax) 8-4 16-8 Super-sulphate of alumina and po ash (alum) potash 5 50 133 + 100 Super-oxalate of potash ''-' 10 tartrate of potash I4 Q.i Tartrate of potash 25 2 3 and soda - '-_ 20 antimony and potash f 6-6 33 See SALT. 829 TABLE XIII. Boiling points of saturated solutions of Salts, ly MR. T. GRIFFITHS. Journal of Science, xviii. 89. NAMES OF SALTS. DRY SALT IN 100. BOILING POINT. Acetate of soda 60 256 p. Nitrate of soda * * 60 246 Rochelle salt 90 240 Nitre 74 238 Muriate of ammonia 50 236 Sulphate of nickel * Tartrate of potash 65 68 235 234 Muriate of soda 30 224 Nitrate of strontites 53 224 Sulphate of magnesia 57-5 222 Supersulphate of potash * ? 222 Borax 52-5 222 Phosphate of soda ' ^ p 222 Carbonate of soda ? 220 Muriate of barytes 45 220 Sulphate of zinc 45 220 Alum 52 220 Oxalate of potash 40 220 Oxalate of ammonia 29 218 Prussiate of potash 55 218 Chlorate of potash . 40 218 Boracic acid . . ? 218 Sulphate of potash and copper Sulphate of copper 40 45 217 216 Sulphate of iron 64 216 Nitrate of lead 52-5 216 Acetate of lead 41-5 215 Sulphate of potash Nitrate of barytes 17-5 26-5 215 214 Bitartrate of potash Acetate of copper 95 16-5 214 214 Prussiate of mercury 35 214 Corrosive sublimate ? 214 Sulphate of soda 31-5 213 THE END. "' LONDON : HOMAS DAVISON, WHITEFRIARS. f OF CALIFORNIA Y LIBRARY OF THE UNIVERSITY OF CALIFORNIA OF CALIF /86&1 M^SS* ISITY OF CALIFORNIA -.^44^41 ^ ^N>m>>~ s - 87 *e SITY OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRA SITY OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRA 9 - (P -2 ~ ^ I 6