OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRARY OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRARY 3F CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA LIBRARY jgsfrj MMMMM** 1RSITY OF Ci LIFORNIA ?S LIBRARY OF THE UNIVERSITY OF CALIFORNIA 9 - (? ^ ~ ^: | I a=-6 ^Q iRSITY OF CALIFORNIA Vj LIBRARY OF THE UNIVERSITY OF CALIFORNIA ^ = /^ a^o ^^^3<^ v\Q ERSITY OF CALIFORNIA LIBRARY OF THE UNIVERSITY OF CALIFORNIA DICTIONARY OF CHEMISTRY, ON THE BASIS OF MR. NICHOLSON'S; IN WHICH THE PRINCIPLES OF THE SCIENCE ARE INVESTIGATED ANEW, AND ITS APPLICATIONS TO THE PHENOMENA OF NATURE, MEDICINE, MINERALOGY, AGRICULTURE, AND MANUFACTURES, DETAILED. BY ANDREW URE, M. D. I'HOIESSOR OF THE ANDERSONIAN INSTITUTION, MEMBER OF THE GEOLOGICAL SOCIETY, &c. &c. WITH AN 3}ntr0twctorp CONTAINING INSTRUCTIONS FOR CONVERTING THE ALPHABETICAL ARRANGEMENT INTO A SYSTEMATIC ORDER OF STUDY. FIRST AMERICAN EDITION,- WITH SOME ADDITIONS, NOTES, AND CORRECTIONS, BY ROBERT HARE, M. D. PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF PENNSYLVANIA. ASSISTED BY FRANKLIN BACHE, M. D. MEMBER OF THE AMERICAN PHILOSOPHICAL SOCIETY, AND OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA. IN TWO VOLUMES, VOL. I. PHILADELPHIA: PUBLISHED BY ROBERT DESILVER, No. 110, WALNUT STREET Eastern District of Pennsylvania, to wit: BE IT REMEMBERED, That on the thirteenth day of October, in the forty-sixth year of the independence of the United States of America, A. D. 1821, Robert Desil- ver, of the said district, hath deposited in this office the title of a book, the right thereof he claims as proprietor, in the words following, to wit : " A Dictionary of Chemistry on the basis of Mr. Nicholson's ; in which the prin- " ciples of the Science are investigated anew, and its applications to the phenomena ** of Nature, Medicine, Mineralogy, Agriculture, and Manufactures, detailed. By An- - " drew Ure, M. D. Professor of the Andersonian Institution, Member of the Geologi- " cal Society, From his quarto Dictionary of 1795. The long article Ores, for h x INTRODUCTION, example, was taken chiefly from Cramer, while the labours of Klaproth and Vauquelin were seldom noticed. Large excerpts were also given from obsolete Dispensatories, concerning substances of no chemical importance, and destitute of all medicinal power. 2d, From the contemporary systems of Brongniart, Henry, Murray, Thomson, Sec. about another fourth was copied in continuous articles. This formed the best part of the whole. 3d, Large excerpts were given from his own Journal, quite dispropor- tionate to the rest of the work, and to the exclusion of numerous interest- ing topics. Indeed a journalist, who compiles a system, has great tempta- tions to fall into this practice* 4th, The fourth portion was composed by himself. This seems to have constituted about one-twentieth of the Dictionary, and related chiefly to physics, in which he was experimentally versant. These articles were very respectable, and have been in some measure retained; see detrac- tion, Balance, Hydrometer, and Laboratory. What follows the first asterisk in Attraction, has been now added. Mr. Nicholson was indeed a man of candour, intelligence, and ingenuity. His original papers on electricity, and mechanical science, do him much honour; and the ab- stracts of experimental chemical memoirs, which he occasionally drew up for his Journal, were ably executed. Had he bestowed corresponding pains on his 8vo Dictionary, my present task would have been greatly lighter. After making such a survey, the feelings under which I began to labour were similar to those of an architect, who having undertaken to repair a building within a certain period, by replacing a few unsightly or moulder- ing stones, finds himself, on his first operations, overwhelmed in its rubbish. Reverence to public opinion, and anxiety to fulfil my engagement, how- ever irksome, have induced me to make every possible exertion to restore the edifice, and renew the decayed parts with solid materials. If it has not all the symmetry, or compactness, of an original design, leisurely exe- cuted, still I trust it will prove not altogether unworthy the attention ot the chemical world. I have investigated the foundation of almost every fact or statement which it contains, and believe they merit general confi- dence. Many inaccurate positions and deductions, in our most elaborate modern system, I have taken the liberty of pointing out; aware that the influence of Dr. Thomson's name and manner is capable of giving consi- derable currency to his opinions, however erroneous they may be. His in- dustry deserves the highest praise ; and his chemical experience would entitle his decisions to deference, were they less precipitate, and less dog- matical. Many of my embarrassments in compiling the present volume, have arisen from his contradictory judgments, pronounced in the Annals of Philosophy; see ACIDS PHOSPHORIC, PRUSSIC', Sec. If under the in- fluence of the feelings thus excited, a hasty expression has escaped me in the ardour of composition, I hope it will not be imputed to personal ani- mosity. I have always lived on amicable terms with this distinguished chemist, and trust to continue so to do. Perhaps in commenting on his opinions, I may have unconsciously caught the plain manner of his criti- cisms. My sole object, however, was the establishment of truth. The refutation of error was undertaken, only when its existence seemed in- compatible with that object. On our other valuable systematic works, I have made no critique, because Dr. Thomson's is the most comprehen- sive, professedly taken from original memoirs, and of highest authority. I Have long meditated to publish a methodical treatise on chemistry, in which both its study and practice would be greatly simplified, and its . applications to the phenomena of nature, medicine, and the arts, faithfully INTRODUCTION. XJ detailed. In my memoir on sulphuric acid, inserted in the Journal of Science and the Arts, for October 1817, is the following passage: " I was led to examine the subject very minutely, in preparing for publication a general system of chemical instructions, to enable apothecaries, manufac- turing chemists, and dealers, to practise analysis with accuracy and des- patch, as far as their respective arts and callings require. I hope that this work will soon appear. Meanwhile, the following details will afford a specimen of the experimental researches executed with this view." The three years and a half which have elapsed since the above paper was com- posed, would have enabled me to fulfil the promise, but for various un- foreseen interruptions to my labours. If the public, after this larger specimen of my chemical studies, shall deem me qualified for the task, I may promise its completion within a year from this date. The work will be comprised in four octavo volumes, and will con- tain the results of numerous investigations into the various objects of prac- tical chemistry, joined to a systematic view of its principles. By several simple instruments, tables, and rules of calculation, chemical analysis, the highest and most intricate part of the science, may, I apprehend, be, in many cases, brought within the reach of the busy manufacturer; while, by the same means, such accuracy and despatch may be insured, as to render the analysis of saline mixtures, complex minerals, and mineral waters, the work of an hour or two; the proportions of the constituents being deter- mined to one part in the thousand. In prosecution of this plan of simplifying analysis, I contrived, about five years ago, an alkalimeter and acidimeter. Being then connected by a biennial engagement with the Belfast Academical Institution, I was oc- casionally called upon to examine the barillas and potashes so extensively employed in the linen manufacture, the staple trade of Ireland. I \vas sorry to observe, that while these materials of bleaching differed exces- sively in their qualities, no means was possessed by those who imported or who used them, of ascertaining their value; and that a generous people, with whom every stranger becomes a friend, frequently paid an exorbitant price for adulterated articles. The method which I devised for analyzing alkaline and acid matter, was laid before the Honourable Linen Board in Dublin, and by them referred to a competent chemical tribunal. The most decisive testimonies of its accuracy and importance were given by that tribunal ; and it 'was finally submitted, by desire of the Board, to a public meeting of bleachers assembled at Belfast. Unexceptionable docu- ments of its practicability and value were thence returned to Dublin, accompanied by an official request, that measures might immediately be taken to introduce the method into general use. Descroizilles had seve- ral years before described, in the Annales de Chimie, an alkalimeter, but so clumsy, operose, and indirect, as to be not at all adapted to the purposes of the linen manufacture. My instrument, indeed, was founded, as well as his, on the old principle of neutralizing alkali with acid; but in every other respect it was different. After spending about two months on this project, and no answer being returned either to the public request of the bleachers, or to my own me- morial, I set off on an intended tour to France, and have never since re- sumed the negotiation.* The terms on which I had offered the instru- ment, were merely honorary; for the sum proposed, would not have re- paid the expense of my journey and attendance. However important there- * The Right Hon. John Foster, who took the chief direction of the Board, showed me every possible attention; but from the absence of many ofits members in England, a quorum ?onld not be assembled at the time. X\i INTRODUCTION. fore the adoption of that instrument was to Ireland, it was of no pecuniary importance whatever to me. Of the two hundred and ten thousand pounds expended that year (1815-1816) on imported alkalies, a very large pro- portion might have been saved by the application of my alkalimeter; and what is perhaps of more consequence, the alkaline leys used in bleaching, would, by its means, havebeen rendered of a regulated strength, suited to the stage of the process, and fabric of the cloth. What would we say of a company, who imported spirituous liquors to an enormous amount, and paid for them all as proof, though they were diluted with fifty per cent, of water? Now, though this neglect of the hydrometer would have a happy moral influence on the consumer, it would be vastly absurd in the dealer. No such apology can be offered for neglecting the alkalimeter. The following is an extract from the Belfast News-Letter of July 9, 1816: " I now submit the following document to public inspection, and hum- bly ask, whether any such experiment has been ever made publicly be- fore; or whether there is described in any publication prior to my late exhibition in Dublin, and in the Linen Hall of Belfast, an instrument by which it can be performed? " This day, one of the porters of the Linen Hall, Belfast, was called into the Library -room, at the request of Dr. Ure, who, being quite un- known to Dr. Ure, and never having seen any experiments made with acids and alkalies, he took the instrument at our desire, which, being filled with coloured acid, by pouring it slowly on adulterated alkali, which we had previously prepared, he ascertained exactly the per centage of genuine alkali in the mixture. Belfast 2,5th June, 1816. (Signed) JOHN S. FERGUSON, Chairman. JAMES M'DONNEL, M. D. JOHN M. STOUPE, S. THOMSON, M. D. " The above experiment did not occupy the porter above five minutes. 1 believe it is a new document, though, after the egg has been placed on end, others will set to work to do the same. " Though the instrument was entirely the result of my own experiments and calculations, I never claimed a greater share in its invention, than I hope its peculiarity merits. The following excerpt from a letter addressed to the Right Hon. John Foster, prior to any public discussion on its me- rits, will satisfy the public on this head. Dublin, June 12, 1816. " SIR, In the letter which I had yesterday the honour of addressing you, I omitted some scientific details, which I now beg leave to submit to your consideration. That the quantity of alkali, present in any portion of potash or barilla, is directly proportional to the quantity of acid requisite to produce saturation, is a fact which has been known for upwards of a century to every chemist, and forms a fundamental law of his science. In establishing my instrument on this law, the principle of it may be said not to be new." Sec. " The practica-. application of the established laws of nature, or of the general deductions of science, to the uses of life, is, perhaps, the most beneficial and meritorious employment of the philosophic mind. The novelty \vhich I lay claim to in my contrivance, is this, that it enables a person versant neither in chemical researches nor in arithmetical computa- tion^ to determine by inspection of a scale, as simple as that of a thermo- meter, the purity or value to one part in the hundred, of the alkalies, oil of vitriol, and oxyrnuriate of lime, so extensively, and often so injudiciously employed by the linen-bleaqher." INTRODUCTION. In my journey through England to France, I submitted my Essay on Alkalimetry, See. to Dr. Henry, in the confidence of friendship, and under the injunction of secrecy. From the unreserved communication of ideas, however, which subsists between this chemist and his townsman Mr. Dai- ton, he soon gave him a perusal of the Essay. In the then existing edi- tion of Dr. Henry's Elements, Descroizilles* plan for testing alkalies was alone given; in the edition published since, he has inserted four supple- mentary pages entitled, " Im}ira-ved Alkalimeter and Acidimeter" This instrument is essentially mine, very slightly disguised. He concludes by saying, " No chemical operation can be more simple, or more easily- managed, than the measurement of the strength of alkalies by acid liquors, and of acids by alkaline ones, in the way which has bten dfscribtd " This is exactly Columbus's egg, or Roger Bacon's gunpowder; et sic fades tonitrit) si SCIAS ARTIFICIUM. By comparing his new way taken from my Essay, with the methods which he formerly gave, the world will see whence the simplification originated. I offered to give him an abridged account of my plan, for insertion in his Elements, after my negotiation about the alkalimeter was finished. Without consulting me on the sub- ject, he publishes to the whole world, what he conceives to be the essence of my improvement.* Two motives have hitherto withheld me from laying the instrument before the public. First, a desire to render it as complete as possible; and secondly, an expectation, that the Honourable Board, who superin- tend the linen manufactures of Ireland with extensive powers, might wish that an instrument originally presented to them, and which is capable ol giving light and precision to all the processes of bleaching, should appear under their auspices. As it now exists, the instrument is greatly superior to that described by Dr. Henry. For the commercial alkalies and acids, I use only two test liquids and one scale; and these are such, that a man unacquainted with science, may prepare the first, and verify the second. The instrument is at once an alkalimeter, an acidimeter, a complete lactometer, a nitrometer for estimating the value of nitre, an indigometer for ascertaining the dyeing quality of indigo, and a blanchimeter for measuring the bleaching power of oxymuriate (chloride) of lime and potash. With it, a busy manufac- turer or illiterate workman may solve all these useful problems in a few minutes ; and many others, such as the composition of alloys of silver, of copper, tin, lead, Sec. the purity of white lead, and other pigments. It is, moreover, a convenient hydrometer, comprehending in its range, light and heavy liquids, from ether to oil of vitriol; and is particularly adapted to take the specific gravity of soils. It may be said, that the solution of the above problems may be accom- plished by any skilful chemist. But surely, in a manufacturing nation, the person who brings the science of Klaproth, Sir H. Davy, Dr. Wollas- ton, and M. Gay-Lussac, into the workshop of the manufacturer, is not a useless member of the community. The result of numerous researches made with that view, has shown m< the possibility of rendering analysis in general, a much easier, quicker, and more certain operation, than it seems hitherto to have been, in ordi- * It "A'onld seem that Dr. Ure lias since been satisfied that Dr. Henry intended him no in- justice, as tills gentleman has explained to him, that in a passage of his Elements, " page 512, vol ii. he intended to give Dr. Ure the credit of inventing an instrument on the principle of directly, and without calculation, indicating; the per centage of alkali in nny specimen, and that he pretended to nothing mor^ than a modification of Dr. Ure's method " See Letter ef Dr. Ure, in the Journal of Science, No. 22, p. 401, -Tnly, 1820. American Editor. INTRODUCTION. nary hands. To these practical applications of science, my attention has been particularly directed, in conducting that department of Anderson's Institution, destined to diffuse among the manufacturers and mechanics of Glasgow and its neighbourhood, a knowledge of the scientific principles of their respective arts. In a public address, delivered to the members of this class, on a gratifying occasion in April 1816, I remarked, " That Europe affords no similar example of a class, composed of several hun- dred artisans, mechanicians, and engineers, weekly assembled,* with exemplary decorum, to study the scientific principles of the useful arts; to have the great practical truths of philosophy, first revealed by Newton and Lavoisier, made level to tlfeir various capacities by familiar descrip- tions, models, and experiments. The original design of the mechanic's class was limited, as you know, to the exhibition and explanation of me- chanical models. But a subject deserving particular attention, was that of the chemical arts, in which many of you are engaged; a knowledge of the scientific principles of which, as taught in the Colleges, circumstances permit few of you to acquire. You have listened to my chemical lessons with the keenest interest; and have applied your studies to conspicuous advantage. Need I adduce, among other things, the unrivalled beauty oi the Adrianople madder dye, as executed on the most extensive scale, f by individuals who have been my faithful pupils, for nearly the whole course of my public career. By a steady prosecution of this expanded system of instruction, your class has progressively increased in number and impor- tance; so that, within the last twelve years, I have delivered twenty-one courses of lectures to upwards of six thousand students in this department alone." It is much to be desired, that similar courses of prelections were insti- tuted in all the large towns of the British empire. The deportment of the mechanic's class, amounting occasionally to five hundred members, jmight serve as a pattern to more dignified assemblies. I have never seen any University class so silent and attentive. Though the evening on which the workmen meet, be that in which they receive their wages, and when, therefore, they might be expected to indulge themselves in drinking, yet no instance of intemperance has ever occurred to annoy the audience. And even during the alarms of insurrection with which our city was dis- turbed last winter, the artisans continued with unaltered docility and punctuality to frequent the lectures. Of the actual result of such a system of instruction, a stranger is pro- bably the best judge. I shall therefore quote a few sentences from the Scientific Tour through Great Britain, recently published by an accom- plished member of the Institute of France, M. Ch. Dupin. " It is easier to visit the establishments and manufactures of Glasgow, than those of any other city in the British empire. The liberal spirit of the inhabitants, is, in this respect, carried as far as possible, among a manufacturing people, who must naturally dread, and seek to prevent, not only the loss of their preponderance, but their foreign rivalry. " The rich inhabitants of Glasgow have founded the Andersonian In- stitution, where are taught, in the evenings of winter, the elements of mechanics, physics, and chemistry, as applied to the arts. These courses are especially designed for young artisans, who have to pay only about five shillings in the season (course of three months.) * Every Saturday evening at eight o'clock. ; Particularly at the establishment of H. Monteith, Esq. M. P. where the sciences of me- chanics and chemistry co-operate, in a flesree of precision an ' elegance, which I believe << ?>e unparalleled in the ->vorld. INTRODUCTION. xv * This trifling fee is exacted, in order that the class may include only students actuated by the love of instruction, and willing to make some small sacrifice for it. " The Andersonian Institution has produced astonishing effects. It is an admirable thing now, t6 see in many Glasgow manufactories, simple workmen, who understand, and explain when necessary, the principles of their operations, and the theoretical means of arriving at the most perfect possible practical results." The philanthropist may perhaps wish to know, at what expense of patronage this useful department is carried on. I shall satisfy this desire, by the following statement from the above mentioned public address. u The original design of the mechanic's class was limited, as you know, to the exhibition and explanation of mechanical models. But the pro- gress of machinery in your workshops, has now so far outrun the state of the models left by the venerable Founder of the Institution, as to render their display, with a very few exceptions, useless, except as historical documents of the rudeness of the times in which they were framed. 1 have, accordingly, for ten years, employed chiefly modern apparatus, pro- cured at my own expense, and by rendering the instructions miscella- neous, have adapted them better to the diversity of your pursuits. Be- sides teaching the usual elements of mechanics and their general combi- nations, I have made it my business to explain the properties of the at- mosphere, on which the action of pumps depends ; the nature of hydro static equilibrium, and hydraulic impulse, as subservient to the construc- tion of Bramah's press, and water-wheels; the beautiful laws of heat so admirably applied to perfect the steam-engine, by our illustrious fellow citizen; nor have I declined, in compliance with your wishes, to lay be- fore you from time to time, such views of the constitution of nature, in electricity, optics, and astronomy, as might awaken the powers of your minds, and reward your attention to the less attractive branches oi science. But a subject, deserving particular attention, was that of the chemical arts/' Sec. (as above quoted.) The whole experimental means at present employed in carrying on this POLYTECHNIC SCHOOL, have been derived from the exertions and sacri- fices of the Professor, and the generous aid and contributions of his pupils. They have supplied him with much valuable practical information on their respective arts, with many curious models, and subsidiary instruments of illustration; while he, in return, has expended large sums of money, in framing popular representations of the scientific discoveries and im- provements, in which the present age is so prolific. To the mechanic's class a library is attached, consisting of the best treatises on the sciences and arts, with some valuable works on general literature, such as history, geography, travels, Sec. of which they have the exclusive management and perusal. -The foundation of it was laid in the year 1807, by a voluntary subscription, amounting, I think, to about 60/.; and several books which I collected from my friends, with about 100 volumes from my own library. Many members of the class have contributed from time to time; and it has recently acquired consider- able extension, from the receipts of lectures which I delivered for its benefit. Besides the acknowledged and palpable effect of such a plan of tuition, on the improvement of the useful arts, it has another operation, more silent, but neither less certain, nor less important, namely, its influence in meliorating the moral condition of the operative order of society. A taste for science elevates the character, and creates a disrelish, and disgust, at the debasement of intoxication. Philosophy dressed in an at- INTRODUCTION. tractive garb, leads away from the temptations of the tavern. Thus, too, the transition from the drudgery or turmoil of the week, to the tranquillity of Sunday, is secured by the preceding evening's occupation. The man indeed whose Saturday night is spent in rioting or drunkenness, will make a bad Christian on the Sabbath, an indifferent workntan on Monday, and an un- happy husband and father through the week. To promote this moral ope- ration of science, I have always taken occasion to point out the beneficent design which the whole mechanism of nature displays. If the contemplation of the miseries and crimes which stain the page of history, have led some speculators to cavil at the government of a benevolent Creator; the con- templation of the harmonious Isfcvs, and benignant adjustments which the science of nature discloses, must satisfy every candid student, of the pre- sence and providence of a wise and beneficent Lawgiver. The first and most exalted function of physics, then, is to dissipate the gloomy and be- wildering mists of metaphysics. A second function of supreme importance., is to point out the mysterious and impassable barriers, to which the clearest paths of physical demonstration ultimately lead the human mind; and thence to inculcate docility to the analogous mysteries of Revelation. I hope that the preceding- statements and remarks, will remove every possible objection to the establishment of schools for teaching the elements of science to artisans, and that they will induce other cities to follow the example so happily set by Glasgow, of popularizing philosophy. Having detailed the circumstances under which I have struggled to re- generate this Dictionary, I hope the candid Public will mak ; e allowance for occasional faults of expression and arrangement. All the articles to which the asterisks are affixed, were, with trifling exceptions, printed from my manuscript, written expressly for this work, within the last five months. From the style of its typography, and the manner of stating proportions of constituents, each page of this volume is fully equivalent to two pages of our octavo systems of chemistry, and required rather more than four pages of closely written manuscript. There is however a great advantage to the reader of a scientific work, (which must necessarily be compiled from many quarters), in an author being his own amanuensis. Every fact and detail will thus be exposed to a much severer scrutiny,_than if excerpts were made by the scissars, or the pen of an assistant. Hence many of the pas- sages which may seem, at first sight, to be merely copied from other works, will be found to have corrections and remarks either interwoven with the details, or enclosed in parentheses. Thus, for example, in transcribing Mr. Hatchett's admirable analyses of the magnetic iron ores, computation will be found within parentheses, deduced from Dr.Wollaston's equivalent scale, Numerous insertions and corrections are made in the reprinted parts to which no asterisk is affixed. M. Vauquelin's general mode of analyzing minerals is now introduced, Professor Gahn's instructions relative to the blow-pipe, a long passage under slrsenious Acid, and many other unnoted insertions, such as Chlorofiftyte, Cholesierine, Comfitonite. The dissertations on Caloric, Combustion, f)e?y.. Distillation, Electricity^ Gas, Light, Thermometer, &c. which form a large proportion of the volume, are beyond the letter and spirit of my engagement with the publisher. I receive no remuneration for them, not even at the most moderate rate of literary labour. They are therefore voluntary contributions to the che- mical student, and have been substituted for what I deemed frivolous and uninteresting details on some unimportant dye-stuffs, and articles from old dispensatories, such as althea, chamomile, &c. For whatever is valuable in the mineralogical department, the reader is ultimately indebted to Professor Jameson. The chief part of the descrip- tions of mineral species, is abridged from the third edition of his excel- INTRODUCTION. xv il lent System. In compiling the early part of the Dictionary, I collated several mineralogical works, both British and foreign ; but I soon found that this had been done to my hand by Professor Jameson, with much greater ability than I could pretend to rival; and that he had enriched the whole with many important remarks of his own. Much of the purely chemical part is drawn from that treasure of facts, Sir H. Davy's elements. When the subject permitted me, I was happy to repose on his never-failing precision, like the wave-tossed mariner in a secure haven. With regard to the language used by him, Dr. Wollaston, M. Gay-Lussac, and some other original investigators, I have used no further freedom than was necessary to accommodate it to the context. Their expressions can very seldom be changed with impunity. There are other chemical writers again, whose thoughts acquire intellectual spring only by great condensation. If the curious reader compare the article DISTILLATION, in this Dictionary, with that in the Supplement to the Encyclopaedia Britannica, he will understand my meaning. In the discussion on the Atomic Theory of Chemistry, under the article EQUIVALENTS, reference is made to a table of the relative weights of the atoms, or of the numbers representing tke prime equivalents of chemical bodies. On subsequent consideration, it was perceived, that such a list would be merely a repetition of numbers already given in their alphabetical places, and therefore most readily found; whilst it would have caused the omission of requisite tables of a different kind; the space allotted to the volume being entirely occupied. In my paper on Sulphuric Acid, published in the 7th number of the Journal of Science, I assigned the numbers 4, 5, 6, as respectively denot- ing the prime equivalents of soda, sulphuric acid, and potash. Minute researches, subsequently made, on the nitrates, (Journal of Science, No, xii.) led me to regard 3.96, and 5.96, as better approximations for soda and potash. Throughout this Dictionary, the numbers 3.95 and 5.95 have been used. It is, however, very possible that the number 6, origi- nally assigned by Sir H. Davy for potash, may be correct; as also 4 fov soda. Dr. Thomson has just published a paper in his Annals, (November 1820J " On the true weight of the atoms of barytes, potash, soda," &c. In his experiments to determine these fundamental quantities, he has adopted Richter's original plan of reciprocal saturation of two neutro-saline compounds. But the Doctor seems to have forgotten, that for want of an initial experiment, none of his ratios is referable to the oxygen scale, or to any atomic radix. He assumes the atom of barytes to be 9.75, and that of potash to be 6; that of sulphuric acid being 5. He then proceeds to show that the atomic weight 13.25 of dry muriate of barytes (chloride of barium), and 11, that of sulphate of potash, produce perfect reciprocal decomposition, when their aqueous solutions are mixed. But had he called the atom of barytes 9.7, with Sir H. Davy and Dr. Wollaston, (the chloride would become 13.2), and the atom of sulphate of potash 10.96, as found in my experiments on nitric acid, he would have obtained, by- mixing the two, in these atomic proportions, as perfect an experimental result as with his own numbers: For 13.25 : 11 : : 13.2 : 10.96, His atomic chain wants, in fact, its first link; it floats loosely; and ma/ therefore be accommodated to a variety of different numbers, provided the arithmetical proportions be observed. He ought to have commenced with a clear demonstration, that the atom of barytes is 9.75, and the atom of potash 6, referred to oxygen as unity. The idea, however, suggested by Dr. Prout, that the numbers repre- senting the weights of the different atoms, are multiples by a whole nuiji* INTRODUCTION. ber of that denoting hydrogen, is very ingenious, and most probably just. And therefore, as well as for experimental reasons, which I cannot here detail, I would willingly adopt 9.75 for barytes, 4 for soda, 6 for potash, and 4.5 for chlorine. The atomic numbers given in this volume, for the various simple and compound objects of chemistry, are directly deduced from a mean of the most exact experiments; and I believe them to be more worthy of confidence, than those deducible from theoretic considerations. Thus, Dr. Thomson, from these, assigns 3.625 for the atom of lime; from experiment, it is certainly not so high. I have stated it from my own, at 3.56. Dr. Marcet's analysis of the carbonate would make it about 3.5. In the article EQUIVALENTS (CHEMICAL), as well as under the individual substances, the reader will find the primitive combining ratios, or atoms as they are hypothetically called, fully, and I trust fairly, investigated from experiment. This is the sheet-anchor of scientific research, which we must never part with, or we shall drift into interminable intricacies. We should continually bear in mind this aphorism of the master of che- mical Logic: *' The substitution of analogy for fact is the bane of chemi- cal philosophy; the legitimate use of analogy is to connect facts together, and to guide to new experiments." Sir H. Da-vy, Journal of Science^ vol. i. These analogical substitutions appear to be the predominant defect of Dr. Thomson's otherwise valuable compilation. The typographical economy of this work precluded me from multiply- ing references at the bottom of the page; a plan which authors readily adopt to show the extent of their reading. The authorities for facts will be generally found interwoven with the text. The desire to condense much practical information, in a small compass, made me abridge many historical details. The progressive steps of an investigation, however, occasionally required to be traced, in order to make the existing state of our knowledge more intelligible. Whenever this seemed necessary, I have offered such a retrospect, and have endeavoured to take truth and justice for my sole guides. As the only recompense which the man of science usually receives or can expect, is the credit of his discoveries, neither prejudice nor passion should be suffered to influence the compiler, in awarding honour to whom honour is due. One of the most elegant investigations which the Science of Chemistry affords, is contained in M . Gay-Lussac's short letter to M. Clement, pub- lished in the Annales de Chimie et de Physique for July 1815, and reprint- ed in 1816, by M. Thenard in his valuable Traite de Chimie, iv. p. 238. It is there demonstrated that sulphuric ether is composed of 2 volumes olefiant gas, 1 volume vapour of water, condensed into one volume; or by weight in M. Gay-Lussac's numbers, of 0.978 x 2 = 1.956 olefiant gas, and 0.625 x 1 = 0.625 vapour of water. 2.581 sum = theoretic density of vapour, which differs from 2.586, the experimental density of ether vapour by only L.^__ parts. This fine coincidence is fully developed by the French che- mist. Now Dr. Thomson was obviously familiar with that paper, for he copies a good part of it, (though without acknowledgment), on the con- stitution of alcohol, into his articles Brewing and Distillation, Su/ifilement to Encyclopedia Britan., as well as into his System published in October 1817, vol. iv. p. 385. See FERMENTATION in this Dictionary. I was therefore equally surprised and amused at the following claim, recently set up by him to M. Gay-Lussac's incontestable discovery. INTRODUCTION. X ix " The experiments which Mr. Dalton has made on the analysis of ether, show in a very satisfactory manner, that the notion which I threw out in my System of Chemistry, that sulphuric ether is a compound of two atoms defiant gas, and one atom vapour of water condensed into one volume, is the true one." t; Hence 2 volumes olefiant gas weigh 1.9416 1 volume vapour of water 0.6250 Total 2.5666 Specific gravity of ether vapour 2.5860." dnnals of Philosophy, August 1820, p. 81. Historical Sketch, &c. by Thomas Thomson, M. D. &c. Now, though in that Sketch the Dr. seems to show, that Mr. Dalton was unacquainted with M. Gay-Lussac's researches on ether, it was a rather rash presumption to extend that analogy of ignorance to all other British Chemists. The first of the Doctor's periods, quoted above, is non- sense, from his u^e of the favourite word atom, instead of volume. The statement in the second is taken from M. Gay-Lussac, and bears the ele- gant impression of its author. Glasgow, Nov. 7, 1820. N. B. -The Articles with ttfe asterisk(*), are inserted by Dr. Ure; the others, with the exceptions noticed in the Introduction, are reprinted from NICHOLSON'S Octavo Dictionary. PREFATORY REMARKS, BY DR. HARE. Being requested by the publisher to make any additions or corrections in this American edition of Ure's Nicholson's Dictionary, which might to me appear proper, I have complied as far the allotted time would per- mit. This, however, was so short, that I have only been enabled to write on some of the topics, concerning which my practical experience, and peculiar and mature reflections, have qualified me to comment advanta- geously. The passages added by me will be distinguished by a cross (f), as those by Dr. Ure are by an asterisk. After the above was written, pursuant to my advice, the publisher en- gaged Dr. Franklin Bache to revise the work, and read the proofs. I feel it due to Dr. Bache to state, that I am under the impression that he has performed his office with zeal and ability; and that I conceive the work will be much indebted to him for its typographical correctness. His sci- entific knowledge has enabled him, not only to prevent various new er- rors, but to correct many previously existing in the original English copy. DICTIONARY OF CHEMISTRY ABS * A BS 9 RBENT - An epithet introduc- I\. ed into chemistry by the physicians, to designate such earthy substances, as seemed to check diarrhoea, by the mere absorption of the redundant liquids. In this sense it is obsolete and unfounded. Professor Leslie has shown that the facul- ty of withdrawing moisture from the air, is not confined to substances which unite with water in every proportion, as the strong acids, dry alkalis, alkaline earths, and deliquescent salts ; but is possessed by insoluble and apparently inert bodies, in various degrees offeree. Hence the term Absorbent merits a place in chemical no- menclature. The substance whose absorbent power is to be examined, after thorough desicca- tion before a fire, is to be immediately transferred into a phial, furnished with a well ground stopper. When it is cooled, a portion of it is transferred into a large wide-mouthed bottle, where it is to be closely confined for some time. A deli- cate hygrometer being then introduced, indicates on its scale the dryness produced in the inclosed air, which should have been previously brought to the point of extreme humidity, by suspending a moist- ened rag within the bottle. The following table exhibits the results of his experi- ments : Alumina causes a dryness of 84 degrees. Carbonate of magnesia ... 75 Carbonate of lime 70 Silica 40 Carbonate of barytes .32 Carbonate of strontites .... 23 Pipe clay 85 Greenstone, or trap in powder 80 ABS Shelly sea sand . 70 degrees. Clay indurated by torrefaction 35 Ditto 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 absor- bent power. This ingenious philosopher infers, that the fertility of soils depends chiefly on their disposition to imbibe mois- ture; and illustrates this idea by recent and by disintegrated lava. May not the finely divided state most penetrable by the deli- cate 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 following quantities of moisture: Ivory 7 gr. boxwood 14, down 16, wool 18, beech 28. Leslie on Heat and Moisture.* AHSOTIPTTO.Y. By this term chemists un- derstand the conversion of a gaseous fluid into a liquid or solid, on being united with some other substance. It differs from con- densation in this being the effect of mecha- nical pressure, or the abstraction of caloric. Thus, if muriatic acid gas be introduced into water, it is absorbed, and muriatic acid is formed ; if carbonic acid gas and ammoniacal gas be brought into contact, absorption takes place, and solid carbo- nate of ammonia is produced by the union of their ponderable bases. There is a case of condensation, which has sometimes no doubt been mistaken for ACH ACl absorption, though none has taken place. When an inverted jar containing 1 a gas con- fined by quicksilver is removed into a trough of water, the quicksilver runs out, and is replaced by water. But as the specific gravity of water is so much infe- rior to that of quicksilver, the column of \vater in the jar resists the atmospheric pressure only with one 14th of the power of the quicksilver, so that the gas occu- pies less room from being condensed by the increased pressure, not from absorp- tion. ABSTRACTION. In the process of* dis- tillation, the volatile products whicli come over, and are condensed in the receivers, are sometimes said to be abstracted from the more fixed part which remains behind. This term is chiefly used when an acid or other fluid is repeatedly poured upon any substance in a retort, and distilled off', with 8 ; for these numbers are inversely as the quan- tity of each 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 statical affinities of Berthollet, where he ascribes such chan- ges not to a superior attraction in the de- composing substance, but to the elastic tendency of that which is evolved. Am- monia separates magnesia from its muri- atic solution at common temperatures ; at the boiling heat of water, magnesia separ- ates ammonia. Carbonate of ammonia, at temperatures under 230, precipitates car- bonate of lime from the muriate ; at high- er temperatures the inverse decomposi- tion takes place with the same ingredients. If the oxalic be a more energetic acid than j- The acid in dry nitre contains water, and of course hydrogen. Liquid nitric acid is obtained from dry nitre by strong sul- phuric acid, and holds, according to the ta- ble in this work, under the head of nitric acid, more than a fifth of water. the carbonic, or rank higher in the scale of acidity, then, on adding to a given weight of liquid muriate of lime, a mix- ture of oxalate and carbonate of ammonia, each in equivalent quantity to the calca- reous 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 muri- ate of soda in the chloridic theory. De- prived 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 sufficient to subvert this whole hypothesis of hydrogenation. 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 properties 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 volume and evolution of heat. 3. W 7 ith a few exceptions they are vo- latilized or decomposed at a moderate heat. 4. They usually change the purple co- lours of vegetables to a bright red. 5. They uni'e in definite proportions f I conceive Mr. Murray's views on this subject as nearer the truth than those of the editor. 1 had adopted conclusions somewhat similar, ere J met with them. - .\s the characteristic attributes of acidity are never observed in the absence of mois- ture, water would seem to have higher pretensions to be considered as the acidi- fying principle than any other ponderable substance. It may be a question, whether acids in a very high state of dephlegmation are really acids or act as such. They do not merely change vegetable blues ; they destroy them. They do not produce a sour taste upon the tongue, they cauterize it, and are destructive of, or are destroyed by, sub- s t ances, which, in a weaker state, they would combine with, so as to yield them up uninjured in obedience to higher affi- nities. Concentrated sulphuric acid destroys or- ganic products, by taking up the elements AC1 ACI With the alkalis, earths, and metallic oxides, and form the important class of salts. This may be reckoned their characteristic and indispensable property. The powers of the different acids were originally estimat- ed by their relative causticity and sour- ness, afterwards by the scale of their at- tractive 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 pow- ers. " The power with which tb^y 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 ascer- taining 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 al- kaline base, is in the inverse ratio of the ponderable quantity of each of them which is necessary to neutralize an equal quanti- ty of the same alkaline base. An acid is, therefore in this view, the more powerful, when an equal weight can saturate a great- er quantity of an alkali. Hence, all those substances 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 pro- perty, it should be employed to form a scale of the comparative power of alkalis as well as that of acids. However plausible, a priori, the opinion of water and leaving the carbon. Hence its blackening power. When diluted, it acts in a totally different way. Of course if it be an acid in the last case, it cannot be so in the first. In evolving carbon by its action on alcohol, it isprecisely analogous to pot- ash, which darkens that fluid, and evolves a carbonaceous resin, which may be seen when the alcoholic solution of that alkali is evaporated, in order to obtain the hydrate. It seems to me that the galvanic fluid is the acidifying principle, and that the acid state is the consequence of galvanic ar- rangements or polarities. It is known that moisture is indispensable to the efficiency of these. On adding water to concentrated sulphu- ric acid, the hydrogen and oxygen seve- rally go to the different poles of the pre- vious compound. Hence the hydrogen evolved by iron or zinc and diluted sul- phuric acid, does not come from a simul- taneous, but a previous decomposition of water. of this illustrious philosopher may be, that the smaller the quantity of an acid or alka- li required to saturate a given quantity of its antagonist 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 36 of magnesia, and by 52 of lime. Hence, by Berthollet'srule, the powers of these earths ought to be as the inverse 1 1 of their quantities, viz. and ; yet 36$ 52$ the very opposite effect takes place, for lime separates magnesia from nitric acid. And, in the present example, the differ- ence of effect cannot be imputed to the difference offeree with which the substan- ces 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 im- portance. Experiment furnishes us with the order of decomposition ofoneacido- alkaline compound by another acid, wheth- er 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 appa- rently a surcharge of oxygen, and thus pro- ducing a new class of bodies, the oxygen- ized acids, which he has had the good for- tune of forming and making known to the chemical world. The first notice of these new compounds appeared in the Jinn, de Chimie et Physique, viii. 306. for July 1818, since which time several additional com- munications of a very interesting nature have been made by the same celebrated chemist. He has likewise formed a com- pound of water with oxygen, in which the proportion of the latter principle is dou- bled, or 616 times its volume is added. The methods of oxygenizing the liquid acids and water, agree in this, that deu- toxide of barium is formed first of all, from which the above liquids, by a subsequent process, derive their oxygen. He pre- scribes 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 cer- tain means of procuring it, is to dissolve the nitrate in water, to add to the solution a small excess of barytes water, to filter and crystallize. 2. The pure nitrate is to be decomposed 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 ACI ACI white porcelain retort. Four orfive 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 considerable quantity of si- lex and alumina ; but it will have only very minute traces of manganese andiron, 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 1 and large enough to contain from 2 to 3^ libs. 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. However rapid the current, the gas is com- pletely absorbed; so that when it passes by the small tube, which ought to termi- nate the larger one, it may be concluded that the deutoxide of barium is completed. It is, however, right to continue the cur- rent for seven or eight minutes more. Then the tube being nearly cold, the deu- toxide, which is of a light grey colour, is taken out, and preserved in stoppered bot- tles. When this is moistened it falls to powder, without much increase of temper- ature. 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 evolu- tion of any gas. The solution is neutral, or has no action on turnsole or turmeric. When we add to this solution the requi- site quantity of sulphuric acid, a copious precipitate of barytes falls, and the filtered liquor is merely water, holding in solution the oxygenized acid, or deutoxide of hy- drogen, combined 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 spe- cific distribution is now requisite. They have also been arranged into those which have a single, and those which have a com- pound basis or radical. But this arrange- ment is not only vague, but liable in other respects to considerable objections. The chief advantage of a classification is to give general views to beginners in the study, by grouping together such substan- ces as have analogous properties or com- position. 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 recourse 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 supposed acidifiers. Family 1st. Oxygen acids. Section 1st, Non-metallic. 1. Boracic. 9. Hypophosphorous. 2. Carbonic. 10. Phosphorous. 3. Chloric. 11. Phosphoric. 4 Perchloric. 12. Hyposulphurous. 5. Chloro-carbonic. 13. Sulphurous. 6. Nitrous. 14. Sulphuric. 7. Nitric. 15. Hyposulphuric. 8. lodic. 16. Cyanic ? Section 2d, Oxygen acids. Metallic. 1. Arsenic. 6. Columbic. 2. Arsenious. 7. Molybdic. 3. Antimonious. 8. Molybdous. 4. Antimonic. 9. Tungstic. 5. Chromic. Family 2d. Hydrogen acids. 1. Fluoric. 5. Hydroprussic. 2. Hydriodic. 6. Hydrosulphurous. 3. Hydrochloric. 7. Hydrotellurous. 4. Ferroprussic. 8. Sulphuroprussie. Family 3d. Acids without oxygen or hydrogen. 1. Chloriodic. 3. Fluoboric. 2. Chloroprussic. 4. Fluosilicic. Division 2d. Acids of organic origin. 1. Aceric. 20. Margaric. 2. Acetic. 21. Melassic. 3. Amniotic. 22. Mellitic. 4. Benzoic. 23. Moroxylic. 5. Boletic. 24. Mucic. 6. Camphoric. 25. Oleic. 7. Caseic. 26. Oxalic. 8. Citric. 27. Purpuric. 9. Formic. 28 Pyrolithic. 10. Fungic. 29. Pyromalic. 11. Gallic. 30. Pyrotartaric. 12. Kinic. 31. Rosacic. 13. Laccic. 32. Saclactic. 14. Lactic. 33. Sebacic. 15. Lampic. 34. Suberic. 16. Lithic. 35. Succinic. 17. Malic. 36. Sulphovinic ? 18. Meconic. 37. Tartaric. 19. Menispermic. 38. Zumic. The acids of the last division are all decom- posable at a red heat, and afford general- ly 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 together which gradu- ate, so to speak, into each other, as hypo- sulphurous, sulphurous and sulphuric.* * ACID (ACEUTC). A peculiar acid said to exist in the juice of the maple. It is de- composed by heat, like the other vegetable acids.* * ACID (ACETIC). The same acid which, in a very dilute and somewhat impure state, is called vinegar. AC1 ACI This acid is found combined with potash in the juices of a great many plants ; par- ticularly the sambucus nigra, phoenix dac- tilifera, galium verum, and rhus typhinus. S\veat,urine. and even fresh milk contain it. It is frequently generated in the stomachs of dyspeptic patients. Almost all dry veg- etable substances, and some animal, sub- jected in close vessels to a red heat, yield it copiously, it is the result likewise of a spon- taneous fermentatioUjto which liquid veget- able, and animal matters are liable. Strong acids, as the sulphuric and nitric, develope the acetic by their action on vegetables. It was long supposed, on the authority of Boerhaave, that the fermentation which forms vinegar is uniformly preceded by the vinous. This is a mistake. Cabbages sour in water, making sour crout ; starch in starch-makers' sour waters ; and dough it- self, without any previous production of wine. The varieties of acetic acids known in commerce are four: 1st, Wine vinegar; 2d, Malt vinegar; 3d, Sugar vinegar ; 4th, Wood vinegar. We shall describe first the. mode of making these commercial arti- cles, and then that of extracting the abso- lute acetic acid of the chemist, eitherfrom these vinegars, or directly from chemical compounds, of which it is a constituent. The following is the plan of making vin- egar 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 superincumbent 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 skilful regulation of the fermentative temperature consists the art of making good wine vinegar. In summer the process is generally comple- ted in a fortnight; in winter double the time is requisite. The vinegar is then run wffinto 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 matter, it does not readily undergo the acetous fer- mentation. In 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 1 ag, that if we moisten roses, or lilies with'al- cohol, 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 supernatent li- quid, 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 veast, 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 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, with- out 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 de- posited by means of isinglass and repose, are thus jumbled into the liquor, and make the fermentation recommence. Almost all the vinegar of the north of France being prepared at Orleans, the manufactory of that place has acquired such celebrity, as to render their process wor- thy 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 diam- eter, kept always open. The wine for ace- tification is kept in adjoining casks,contain- ing beech shavings, to which the lees ad- here. The wine thus clarified is drawn off to make vinegar. 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 liquid ; and according to the quantity of froth which the spatula shows, they add more or less wine. In summer, the atmos- pheric 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 ACI ACI which they pour such wine as they wish to acetify ; and it is always preserved full, by replacing" the vinegar drawn off, by new wine. To establish this household manu- facture, it is only necessary 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 buckwheat. These grains are ground, mixed, and boil- ed, along with twenty-seven casks-full of river water, for three hours. Eighteen I casks of good beer for vinegar are obtain- | ed. By a subsequent decoction, more fer- i mentable liquid is extracted, which is mix- ed 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 loose- ly covered, to the influence of the sun in summer ; but in winter they are arranged in a stove-room. In three months this vinegar is ready for the manufacture of su- gar of lead. To make vinegar for domes- tic 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 n. consid- erable 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 vinegar is fully fermented, iu above, without the rape, which is added towards the end, to communicate flavour. Two large casks are in this case worked togeth- er, as is described long ago by LJocrhaave, as follows. " Take two large wooden vats, or hogs- heads, and in each cf these place a wooden grate or hurdle, at the distance of a foot from the bottom. 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, commonly 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 Von. I-. F21 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, keep- ing 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 fermen- tative motion, accompanied with a sensible heat, which will gradually increase from day to day. On the contrary, the ferment- ing motion is almost imperceptible in the full vessel ; and as the two vessels are al- ternately full and half full, the fermenta- tion is by this means in some measure in- terrupted, and is only renewed every other day in each vessel. " When this motion appears to have en- tirely ceased, even in the half filled vessel, it is a sign 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 accelerates or checks this, as well as the spirituous 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, (88^ Fahr.) the half filled vessel must be filled up eve- ry twelve hours ; because, if the fermen- tation 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 de- pends, 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 spirituous parts, it is a proper and usual precaution 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 air may act freely on the liquor it con- tains ; for it is not liable to the same in- conveniences, because it ferments but very slowly." Good vinegar may be made from a weak sirup, consisting of 18 oz. of sugar to eve- ry 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 momentary ebullition before it is bottled is found favourable to its preserva- tion. In a large manufactory of malt vine- gar, 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 pe- culiar but rather gratpfi-H smelt. By dts- ACI ACI tiilation in glass vessels the colouring mat- ter, which resides in a mucilage, is sepa- rated, 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 em- pyreu ma increases. Hence only the inter- mediate portions are retained as distilled vinegar. Its specific gravity varief from 1.005 to 1.015, while that of common vin- egar 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, are built horizontally in brick work, so that the flame of one fur- nace 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 cvvt. 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 furnace is allowed to cool during the night. Next morning the door is opened, the charcoal 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 there- fore about SOOlbs. But the residuary char- coal 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 charcoal is equal in weight to more than four-tenths of the wood from which it is made. And M. Clement says that it is equal to one- half. 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 ex- perience of an eminent manufacturing chemist at Glasgow. The crude pyrolig- uous acid is rectified by a second distilla- tion 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 vinegar, having a con- siderable empyreumatic smell, and a sp. gr. of 1.013. Its acid powers are superior to those of the best household vinegar, in the proportion of 3 to 2. By redistilla'ion, saturation with quick-lime, evaporation of the liquid acetate to dry ness, and gentle torrefaction, the empyreumatic matier is so completely dissipated, that on decom- posing the ca'careous salt by sulphuric acid, a pure, perfectly colourless, and grateful vinegar rises in distillation. Its strength will be proportional to the con- centration of the decomposing acid. The acetic acid ot 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 distillation from a glass retort into a refrigerated receiver, concentrated acetic acid. A small portion of sulphurous acid, which contaminates it, may be removed by redistillation, from a little acetate of lead. 2d, Or 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 pi-oportion of 1 of the former to 2 of the latter, and carefully distilled from a porcelain retort into a cooled receiver, may be also considered a good economi- cal process. Or without distillation, if 100 parts of well dried acetate of lime be cau- tiously added to 60 parts of strong sulphu- ric 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 obtaining strong acid. Here, however, the product is mixed with a portion of the fra- grant pyro-acetic spirit, which it is trou- blesome to get rid of. Undoubtedly the best process for the strong acid is that first described, 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, crystallizing in oblong rhomboidal plates. It has an extremely pungent odour, affecting- the nostrils and eyes even painfully, when its vapour is incautiously snuffed up. lis taste is eminently acid and acrid. It excoriates and inflames tho skin. The purified wood vinegar, which is used for pickles and culinary purposes, has commonly a specific gravity of about 1.009; when it is equivalent in acid strength to good wine or malt vinegar of ACI ACI 1.014. It contains about of^ ff 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 re- sults from its saturation with quick-lime. The decimal number of the sp. gr. of the calcareous acetate, is nearly double that of the pure wood vinegar. Thus 1.009 in 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 extractive, the remainder will agree with the density of the acetate from wood. A glass hydrometer of Fahrenheit's con- struction 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 stein above of about 3 inches long, containing a slip of paper with a transverse line in the middle, and surmounted with a little cup for re- ceiving weights or poises. The experi- ments on which this instrument, called an hectometer, is constructed, have been de- tailed in the sixth volume of the Journal of Science. They do not differ essentially from those of Mollerat. The following points were determined by this chemist. The acid of sp. gr. 1.063 requires 2^ times its weight of crystallized subcarbonate of soda for saturation, whence M. Thenard regards it as a compound of 11 of water, and 89 of real acid in the 100 parts. Com- bined 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 di- luting it with a smaller quantity of water, its sp. gr. augments, a circumstance pecu- liar to this acid. It is 1.079, or at its maxi- mum, 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 acetome- ter: Revenue proof acid, called by the man- ufacturer 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 satu- rating perfectly dry charcoal with common vinegar, and then distilling. The water easily comes off, and is separated at first ; hut a stronger heat is required to expel the acid. Or by exposing vinegar to very cold air, or to freezing mixtures, its water sepa- rates 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 apo- thecaries, 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 crystalliz- ed acid. The pungent smelling salt con- sists 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 me- tals, by mixing a solution of their sulphates with that of an acetate of lead. This acid, as it exists in the acetates of barytes and lead, has been analyzed by M. M. 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, 49.665 of water, or its elementary constituents, and 0.111 hy- drogen in excess. Berzelius. 46.83 carb. 6.35 hydr. and 46.82 oxygen in the hundred parts. Their methods are described under VE- GETABLE (AVALYSIS). By saturating known weights of bases with acetic acid, and as* certaining the quantity of acetates obtain- ed after cautious evaporation to dryness, Berzelius obtained with lime (3.55) 6.5 for the prime equivalent of acetic acid, and with yellow oxide of lead 6.4 >2. Recent re- searches, which will be published in a de- tailed form, induce me to fix the prime of acetic acid at 6.63. It would seem to con,- sist, by Berzelius's analysis, of 3 Primes of hydrogen 3.75 6.2 4 carbon 30. 46.9 3 oxygen 30. 46.9 63,75 100.0 The quantity of hydrogen is probably much underrated. Acetic acid dissolves resins, gum-resins, camphor, and essential oils. Its odour is employed in medicine to relieve nervous headaches, faintingfits, or sickness occasioned by crowded rooms. In a slightly dilute state, its application has been found to check hemorrhagy from the nostrils. Its anticontagious powers are now little trusted to. It is very largely used in calico printing. Moderately rec- tified pyrolignous acid hasbeen recommen- ded for the preservation of animal food ; but the empyreumatic taint it communi- cates to bodies immersed in it, is not quite removed by their subsequent ebullition in water. See Acid, (Pyrolignous). Acetic acid and common vinegar are sometimes fraudulently mixed with sal- AC1 ACI phuric acid to give them strength. This adulteration may be detected by the ad- dition of a little chalk, short of their satu- ration. 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 super- saturating them with ammonia, when a fine blue colour is produced ; and lead by sulphate of soda, hydrosulphurets, ilph- uretted hydrogen, and gallic acid. None of these sho-.ild produce any change on genuine vinegar. See LKAD.* * ACID (OXY-ACETIC). Acetic acid dis- solves deutoxide of barium without effer- vescence. By precipitating the barytes with sulphuric acid, there remains an ox- ygenized 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 carbonic acid gas. This shows that the oxygen, when assisted by heat, unites in part with the carbon, and doubt- less likewise with the hydrogen of the acid. It is in fact acetic deutoxide of hy- drogen. Salts consisting of the several bases, united in definite proportions to acetic acid, are called acetates. They are char- acterized by the pungent smell of vinegar, which they exhale on the affusion of sul- phuric acid ; and by their yielding on dis- tillation 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 alka- lis and most of the earths, and with these bases it forms compounds, some of which are crystallizable, and others have not yet been reduced to a regularity of figure. The salts it forms are distinguished by their great solubility; their decomposition by fire, which carbonizes them ; the spontan- eous alteration of their solution ; and their decomposition by a great number ofuc'.ds, 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 formed by the acetic acid does not crystallize; but, when evaporated to dryness, it deliques- ces by exposure to air. This mass is not decomposed by acid of arsenic. By spon- taneous evaporation, however, it will crystallize in fine transparent prismatic 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 regenerated tartar. The solution of this salt, even in closely stopped vessels, is spontaneously decomposed : it deposites a thick, mucous, flocculent sediment, at first gray, and at length black ; till at the end of a few months nothing remains in the liquor but carbonate of potash, rendered impure by a little coaly oil. With soda it forms a crystallizable salt, which does not deliquesce. This salt has very improperly been called mineral foli- ated earth. According to the new nomen- clature it is acetate of soda. The salt formed by dissolving chalk or other calcareous earth in distilled vinegar, formerly called salt of chalk, or fixed vege- table sal ammoniac, and by Bergman calx acetata, has a sharp bitter taste, appears in the form of crystals resembling somewhat ears of corn, which remain dry when ex- posed to the air, unless the acid has been super-abundant, in which case they deli- quesce. By distilling without addition, the acid is separated from the earth, and appears in the form of a white, acid, and in- flammable vapour, which smells like acetic ether, somewhat empyreumatic,and which condenses into a reddish brown liquor. This liquor, being rectified, is very vola- tile and inflammable : upon adding water it acquires a milky appearance, and drops of oil seem to swim upon the surface. After the rectification, a reddish brown li- quor remains behind in the retort, toge. ther with a black thick oil. When this earthy salt is mixed with a solution of sul- phate of soda, the calcareous earth is pre- cipitated along with the sulphuric acid ; the acetic acid uniting with the soda, makes a crystallizable salt, by the calcination of which to whiteness, the soda may be ob- tained. This acetic calcareous salt is not soluble inspirit of wine. Of the acetate of strontian little is known, but that it has a sweet taste, is very solu- ble, and is easily decomposed by a strong heat. The salt formed by uniting vinegar with ammonia, called by the various names of spirit of Mindererus, liquid sal ammoniac, acetous sal ammoniac, and by Bergman al- kali volatile acctatum, is generally in a liquid state, and is commonly believed not to be crystallizable, as in distillation it pass- es entirely over into the receiver. It ne- vertheless may be reduced into the form of small needle-shaped crystals, when this liquor is evaporated to the consistence of a sirup. Westendorf, by adding 1 his concentrated vinegar to carbonate of ammonia, obtained AC1 ACI n pellucid liquid, which did not crystallize ; and which by distillation was totally expell- ed from the retort, leaving- only a white spot. In the receiver, under 'he clear fluid, a transparent saline mass appeared, which being separated from the fluid, and expo- sed to gentle warmth, melted and threw out abundance of white vapours, and in a few minutes shot into sharp crystals resembling th;.-se of nitre. Thf-se crystals remain un- changed while cold, but they melt at 120 and evaporate at about 250. Their taste at first is sharp and then sweet, and they possess the general properties of neutral salts, With magnesia the acetic acid unites, and, after a perfect saturation, forms a vis- cid saline mass, like a solution of gum ara- ble, 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. The acid of this saline mass may be separated by distillation with- out addition. Glucine is readily dissolved bv acetic acid. This solution, as Vauquelin informs us, does not crystallize ; but is reduced by evapora- tion to a gummy substance, which slowly becomes dry and brittle ; retaining a kind of ductility for a long time. It has a sac- charine and pretty strongly astringent taste, in which that of vinegar however, is distin- guishable. Yttria dissolves readily in acetic acid, and the solution yields by evaporation crystals of acetate of yttria. These have common- ly the form of thick six-sided plates, and are not altered by exposure to the air. Alumine, obtained by boiling alum with alkali, and edulcorated by digesting in an alkaline lixivium, is dissolved by distilled vinegar in a very inconsiderable quantity. A considerable quantity of the earth of al- um, precipitated by alkali, and edulcorated by liot water in MargrafPs manner, is solu- ble in vinegar, and a whitish saline mass is then obtained, which is not crystallizable. Fro.n this mass a concentrated acetic acid may be obtained by distillation. Or to a boiling solution of alum in water gradually add a solution of acetate of lead till no fur- ther precipitate ensues. The sulphate of lead having subsided, decant the superna- tant liquor, evaporate, and the acetnte of alumine may be obtained in small needle- shaped crystals, having a strong styptic and acetous taste. This salt is of great use in dyeing and calico printing. See ALU3HNA. Acetate of zircone may be formed by pouring acetic acid on newly precipitated zircone. It has an astringent taste. It does not crystallize ; 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. The acetic acid has no action upon sili- ceous earth ; for the needle-shaped crys- tals observed by Durande in a mixture of vinegar with the earth precipitated from a liquor of flints, do not prove the solubility of siliceous earth, as Leonhardi observes. Concerning the action of vinegar on al-. cohol, see ETHER. This acid has no effect upon fat oils, except that when distilled to- gether, some kind of mixture takes place, as the Abbe Rozier observes. Neither does distilled vinegar act upon essential oils ; but Westendorf 's concentrated acid dissolved about a sixth part of oil of rosemary, or one half its weight, of camphor ; which latter so- lution was inflammable ; and the camphor was precipitated from it by adding water. Vinegar dissolves the true gums, and part- ly the gum-resins, by means of digestion. Boerhaave observes, that vinegar by long boiling dissolves the flesl^cartilag-es, bones, and ligaments of animals. Acin. (AMNIOTIC). On evaporating the liquor amnii of the cow to one-fourth, Vau- quelin and Buniva found, that crystals form in it by cooling. These are contaminated by a portion of extract) ve matter,from which they may be freed by washing with a very small quantity of water. These crystals are white and shining, slightly acid to the taste, redden litmus paper, and are a little more soluble in hot than cold water. They are likewise soluble in alcohol. On ignited coals they swell, turn black, give out am- monia and prussic acid, and leave a bulky coal. With the alkalis this acid forms very soluble salts, but it does not decompose the carbonate without the assistance of heat. It does not precipitate the earthy salts, or the nitrates of mercury, lead, or silver. The acids precipitate it from its combinations with alkalis in a white crystaline powder. Whether it exist in the amniotic liquor of any other animal is not known. ACID (AKSENIC). The earlier chemists were embarrassed in the determination of the nature of the white sublimate, which is obtained during the roasting of cobalt and other metallic ores, known in commerce by the name of arsenic : its solubility in water, its power of combining with metals in their simple state, together with other apparent- ly heterogeneous properties, rendered it difficult to determine whether it ought to be classed with metals or salts. Subse- quent discoveries have shown the relation it bears to both. When treated with com- bustible matter, in close vessels, it sublimes in the metallic form, (See ANSEXIC) ; com- bustion, or any analogous process, converts it into an oxide ; and when the combustion, is carried still further, the arsenical basis becomes itself converted into an acid. ACI ACI \Ve arc indebted to the illustrious Scheele for the discovery of this acid, though Macquer had before noticed its combinations. It may be obtained by va- rious 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 re- main in the retort. This is the arsenic acid. It may equally be procured by means of aqueous chlorine, or by heating concen- trated nitric acid with twice its weight of the solution of the arsenious acid in muri- atic acid. The concrete acid should be ex- posed to a dull red heat for a few minutes. In either case an acid is obtained, that does not crystallize, but attracts the moisture of the air, has 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 the glass retort, and a violent heat applied, the acid boils strongly, and in a quarter of an .hour begins to emit fumes. These, on be- ing received 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. If two parts of arsenic acid be mixed with about one of charcoal, the mixture in- troduced into a glass retort, coated, and a matrass adapted to it ; and the retort then gradually heated in areverberatory furnace, till the bottom is red ; the mass will be in- flamed violently, and the acid reduced, and rise to the neck of the retort in the metal- I'.c state mixed with a little oxide and char- coal powder. A few drops of water, de- void of acidity, will be found in the receiv- er. With sulphur the phenomena are differ- ent. If a mixture of six parts of arsenic acid, and one of powdered s'llphur, be di- gested together, no change will take place ; but on evaporating to dnness, and distill- ing in a glass retort, iitted with a receiver, a violent combination will ensue, as soon as the mixture is sufficiently heated to melt the sulphur. The whole mass rises almost at once, forming ti red sublimate, and sul- phurous acid passes over into the receiver. If pure arsenic acid be diluted with a small quantity of water, and hydrogen gas, as it is evolved by the action of sulphuric prid on iron, be received into this transpa- rent solution, the liquor grows turbid, and a blackish precipitate is formed, which, be- ing well washed with distilled water, ex- hibits all the phenomena of arsenic. Some- times, too, a blackish gray oxide of arsenic is found in this process. If sulphuretted hydrogen gas be employ- ed 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. The arsenic acid is much more soluble than the arsenious. According to Lagrange, two parts of water are sufficient for this pur- pose. It cannot be crystallized by any means ; but, on evaporation, assumes a thick honey-like consistence. No acid has any action upon it : if some of them dissolve it by means of the water that renders them fluid, they do nor pro- duce any alteration in it. The boi'acic and phosphoric are verifiable with it by means of heat, but without any material alteration in their natures. If phosphorous acid be heated upon it for some time, it saturates itself with oxygen, and becomes phospho* ric acid. 1 he arsenic acid combines with the ear- thy and alkaline bases, and forms salts very different from those furnished by the ar- senious acid. All these arseniates are decomposable by charcoal,which separates arsenic from them by means of heat. * Berzelius, from the result of accurate experiments on the arseniates of lead and barytes, infers the prime equivalent of ar- senic acid to be 7/25, oxygen being 1.0 ; but Dr. Thomson, from his experiments on the arseniates of potash and soda, conceives that the double of the above number ought to be preferred, viz. 14.5. Jinn, of Phil, vol. xv. On the latter supposition, BerzeTius's in- soluble salts will consist of two primes of base and one of acid ; and the acid itself will be a compound of 5 of oxygen = 5, + 9.5. of the metallic base = 14.5 ; for direct ex- periments have shown it to consist of 100 metal, and from 52 to 53 oxygen. But 152.5: 100:: 14.5 : 9.5 nearly. 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 ba- rytes or oxide of lead has been precipitated by this acid, its farther addition redissolves the precipitate. This is a useful criterion of the acid, joined to its reduction to the metallic state by charcoal, and ihe other characters already detailed. Sulphuric acid decomposes the arseniates at a lou* temperature, but the sulphates are 'de- composed bv arsenic ac'd at a. red heat, ACI ACI 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 g:trlic smell of the metallic vapour. JNitrate of silver gives a pulverulent brick-coloured precipitate, or, according 1 to Dr. Thomson, a flesh red, with arsenic acid. The acid itself does not disturb the transparency of a solution of sulphate of copper ; but a neutral arseni- ate 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 precipi- tate, but that it exercises no action either on the muriate or acetate of cobalt ; but with the ammonia-muriate it gives a rose- coloured precipitate. 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. * The arseniate of barytes is insoluble, uncrystallizable, soluble in an excess of its acid, and decomposable by sulphuric acid, which precipitates a sulphate of barytes. Of the arseniate of strontian nothing is known, but no doubt it resembles that of barytes. With lime-water this acid forms a pre- cipitate of arseniate of lime, soluble in an excess of its base, or in an excess of its acid, though insoluble alone. The acidu- fous arseniate of lime affords on evapora- tion little crystals, decomposable by sul- phuric acid. The same salt may be formed by adding carbonate of lime to the solu- tion of arsenic acid. This acid does not decompose the nitrate or muriate of lime ; but the saturated alkaline arseniates de- compose them by double affinity, precipi- tating the insoluble calcareous arseniate. If arsenic acid be saturated with magne- sia, a thick substance is formed near the point of saturation. This arseniate of mag- nesia is soluble in an excess of acid ; and on being evaporated takes the form of a jelly, without crystallizing. Neither the sulphate, nitrate, nor muriate of magne- sia is decomposed by arsenic acid, though they are by the saturated alkaline arseni- ates. Arsenic acid saturated with potash does not easily crystallize. This arseniate. be- ing evaporated to dryness, attracts the hu- midity of the air, and turns the sirup of violets green, without altering the solu- tion of litmus. It fiiscs into a white glass, and with a strong 1 fire, is converted into a-n acidule, part of the alkali being abstracted by the silex and alumina of the crucible. If exposed to a red heat with charcoal in close vessels it swells up very much, and arsenic is sublimed. It is decomposed by sulphuric acid; but in the humid way the decomposition is not obvious, as the arse- nic acid remains in solution. On evapora- tion, however, this acid and sulphate of potash are obtained. If arsenic ucid be added to the preceding salt, till it ceases to have any effect on the sirup of violets, it will redden the solu- tion of litmus ; and in this state it afford* very regular and very transparent crystals, of the figure of quadrangular prisms, ter- minated by two tetraedral pyramids, the angles of which answer to those of the prisms. These crystals are the arsenical neutral salt of Macquer. As this salt dif- fers from the preceding arseniate by its crystallizability, its reddening solution of litmus, its not decomposing the calcareous and magnesian salts like it, and its capa- bility of absorbing an additional portion of potash, so as to become neutral, it ought to be distinguished from it by the term of acidulous arseniate of potash. With soda in sufficient quantity to satu- rate it, arsenic acid forms a salt crystalli- zable like the acidulous arseniate of pot- ash. Pelletier says, that the crystals are hexaedral prisms terminated by planes perpendicular to their axis. This neutral arseniate of soda, however, while it differs completely from that of potash in this re- spect, and in becoming deliquescent in- stead of crystallizable on the addition of a surplus portion of arsenic acid, resembles the arseniate of potash in its decomposi- tion by charcoal, by acids, and by the earths. Combined with ammonia, arsenic acid forms a salt affording rhomboida] crystals analogous to those of the nitrate of soda. The arseniate of ammonia, which is pro- duced likewise in the decomposition of nitrate of ammonia by arsenious acid, is decomposable in two ways by the action of heat. If it be gently heated, the ammo- nia is evolved, and the arsenic acid is left pure. If it be exposed to a violent and rapid heat, part of the ammonia and part of the acid reciprocally decompose each other ; water is formed ; azotic gas is given out ; and the arsenic sublimes in a shining- metallic form. Magnesia partly decompo- ses the arseniate of ammonia, and forms a triple salt with a portion of it. Arsenic acid saturated with alumina forms a thick solution, which, being eva- porated to dryness, yields a salt insoluble in water, and decomposable by the sul- phuric, nitric and muriatic acids, as well as by all the other earthy and alkaline ba- ses. The, arsenic acid readily dissolves the ACI ACI alumina of the crucibles in which it is re- duced to a state of fusion ; and thus it at- tacks silex also, on which it has no effect in the humid way. We know nothing 1 of the combination of this acid with zircone. By the assistance of a strong" fire, as Fourcroy asserts, arsenic acid decompo- ses the alkaline and earthy sulphates, even that of barytes ; the sulphuric acid flying" off in vapour, and the arseniate remaining in the retort. It acts in the same manner on the nitrate, from which it expdts the pure acid. It likewise decomposes the muriates at a high temperature, the muri- atic acid being evolved in the form of gas, and the arsenic acid combining with their bases, which it saturates ; while the arse- nious acid is too volatile to have this effect. It acts in the same manner on the fluates, and still more easily on the carbonates, with which, by the assistance of heat, it excites a brisk effervescence. Lagrange, however, denies that it acts on any of the neutral salts, except the sulphate of pot- ash, 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 phos- phates, but precipitates the boracic acid from solutions of borates when heated. Arsenic acid does not act on gold or platina; neither does it on mercury or silver without the aid of a strong heat ; but it oxidizes copper, iron, lead, tin, zinc, bismuth, antimony, cobalt, nickel, manga- nese, and arsenic. This acid is not used in the arts, at least directly, though indirectly it forms a part of some composition used in dyeing. It is likewise one of the mineralizing acids combined by nature with some of the me- tallic oxides. ACID (AnsENiors). 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, and which the au- thors of the new chemical nomenclature had consequently termed oxide of arsenic. As, however, it manifestly exhibits the properties of an acid, though in a slight degree, it has a fair claim to the title ; for many oxides and acids are similar in this, that both consist of a base united with oxygen, and the only difference between them is, that the compound in which the acid properties are manifest is termed an acid, and that in which they are not is called an oxide. This acid, which is one of the most vi- rulent poisons known, frequently occurs in a native state, if not very abundantly ; and it is obtained in roasting several ores, particularly those of dobalt. In the chim- neys of the furnaces where this operation is conducted, it generally condenses in thick semi-transparent masses ; thougli sometimes it assumes the form of a pow- der or of little needles, in which state it was formerly called flowers of arsenic. The arsenious acid reddens the most sensible blue vegetable colours, though it turns the sirup of violets green. On ex- posure to the air it becomes opaque, and covered with a slight efflorescence. Thrown on incandescent coals, it evapo- rates 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 form- ing water, the other carbonic acid, with the oxygen taken from it : as it is by phos- phorus, and by sulphur, which are in part converted into acids by its oxygen, and in part form an arsenical phosphuret or sul- phuret with the ai'senic reduced to the metallic state. Hence Margraafand Pel- letier, who particularly examined the phosphurets of metals, have asserted 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 crystal- lizes, and the acid assumes the form of re- gular tetraedrons according to Fourcroy ; but, according to Lagrange, of octaedrons, and these frequently 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 decomposes the alkaline sulphurets. Arsenious acid is also soluble in oils, spir- its, and alcohol ; the last taking up from 1 to 2 per cent. It is composed of 9.5 of me- tal -t- 3 oxygen ; and its prime equivalent is therefore 12.5. Dr. \Vollaston first ob- served, that when a mixture of it with quick-lime is heated in a glass tube, at a certain temperature, ignition suddenly per- vades the mass, and metallic arsenic sub- limes. As arseniate of lime is found at t he- bottom of the tube, we perceive that a portion of the arsenious acid is robbed of its oxygen, to complete the acidification of the rest.* There are even some metals, which act \ipon the solution, and have a tendency to decompose the acid, so as to form a black- ish precipitate, in which the arsenic is very slightly oxidized. The action of the other acids upon the arsenious is very different from that which they exert on the metal arsenic. By boil- ing, sulphuric acid dissolves a small por- ACI ACI tion of it, which is precipitated as the so- lution cools. The nitric acid does not dis- solve it, but by the help of heat converts it into arsenic acid. Neither the phospho- ric 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 chlorine acidifies it completely, so as to convert it into arsenic acid. The arsenious acid combines with the earthy and alkaline bases. The earthy ar- seniafes possess little solubility, and hence the solutions of barytes, strontian, and ]ime, form precipitates with that of arse- nious acid. The acid enters into another kind of combination with the earths, that formed by vitrification. Though a part of this vola- tile acid sublimes before the glass enters into fusion, part remains fixed in the vitri- fied substance, to which it imparts trans- parency, a homogeneous density, and con- siderable gravity. The arsenical glasses appear to contain a kind of triple salt, since the salt and alkalis enter into an in- timate combination at the instant of fusion, jind remain afterwards perfectly mixed. All of them have the inconvenience of quick- ly growing dull by exposure to the air. With the fixed alkalis the arsenious acid forms thick arsenites, which do not crys- tallize ; which are decomposable by fire, the arsenious acid being volatilized by the heat ; and from which all the other acids precipitate this in powder. These saline compounds were formerly termed livers, because they were supposed to be analo- gous to the combinations of sulphur with the alkalis. With ammonia it forms a salt capable of crystallization. If this be heated a little, the ammonia is decomposed, the nitrogen is evolved, while the hydrogen, uniting with part of the oxygen of the acid, forms water. Neither the earthy nor alkaline arsen- ites have yet been much examined ; what is known of them being only sufficient to distinguish them from the arseniates. The nitrates act on the arsenious acid in a very remarkable manner. On treating the nitrates and arsenious acid together, the nitrous acid, or nitrous vapour, is ex- tricated in a state very difficult to be con- fined, as Kunckel 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 arsenious acid ; for it is still sufficiently combustible to produce a de- tonation, in which no spark* are seen, it is true, but with commotion and efterves* cence ; and a true arseniate remains at the bottom of the crucible. It was in this VOL. I. [3] way chemists formerly prepared their fixed arsenic, which was the acidulous arseni- ate of potash. The nitrate of ammonia ex- hibits different phenomena in its decom- position by arsenious acid, and requires considerable precaution. Pelletier, having mixed equal quantities, introduced the mixture into a large retort of coated glass, placed in a reverberatory furnace, with a globular receiver. He began with a very slight fire ; for the decomposition is so ra- pid, and the nitrous vapours issue with such force, that a portion of 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 comes over; if the fire be continued, or increased, am- monia is next evolved ; and lastly, if the fire be urged, a portion of oxide of arsen- ic sublimes in the form of a white pow- der, and a vitreous mass remains in the re- tort, which powerfully attacks and cor- rodes it. This is arsenic acid. The chlo- rate of potash, too, by completely oxidiz- ing the arsenious acid, converts it into ar- senic acid, which by the assistance of heat, is capable of decomposing the muriate of potash that remains. The arsenious acid is used in numerous instances in the arts, under the name of white arsenic, or of arsenic simply. In many cases it is reduced, and acts in its metallic state. Many attempts have been made to in- troduce it into medicine ; but as it is known to be one of the most violent poi- sons, it is probable that the fear of its bad effects may deprive society of the advan- tages it might afford in this way. An ar* senite of potash was extensively used by the late l)r. Fowler of York, who publish- ed a treatise on it, in intermittent and re- mittent fevers. He likewise assured the writer, that he had found it extremely effi- cacious in periodical headache, and as a to- nic in nervous and other disorders ; and that he never saw the least ill effect from its use, due precaution being employed in preparing and administering it. Exter- nally it has been employed as a caustic to extirpate 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. Febure's remedy was water one pint, extract of hemlock 5J, Goulard's ex- tract giij, tincture of opium gj, arsenious acid gr. x. With this the cancer was wet- ted morning and evening ; and at the same time a small quantity of a weak solution, was administered internally. A still milder application of this kind has been made from a solution of one grain in a quart of water, formed into a poultice with crumb of bread. * It has been mere lately used as an alv ACI ACI terative with advantage in chronic rheu~ matism. The symptoms which show the system to be arsenified are thickness, red- ness, and stiffness of t\\e palpebr6 parts of carbonate of soda, both dissolved in water, filtering the solution, and then set- ting it aside for two or three days. These crystals soon lose their transparen- cy, and become covered with a white pow- der. Exposed to the fire in a crucible, they decrepitate slightly, lose their water and acid, fall to powder, and are reduced to one-fourth of the original weight. When the common carbonate is calcined in the great, it appears as if boiling, from the ex- trication of carbonic acid; a small portion ascends like a vapour, and is deposited in a white powder on the cold bodies with which it comes into contact ; and in a dark place, towards the end of the operation, it shines with a bluish phosphoric light. It thus loses half its weight, and the magne- sia is left quite pure. As the magnesia of the shops is some- times adulterated with chalk, this may be detected by the addition of a little sulphu- ric acid diluted with 8 or 10 times its weight of water, as this will form with the magnesia a very soluble salt, while the sulphate of lime will remain undissolved. Calcined magnesia should dissolve in this dilute acid without any effervescence. The crystallized carbonate dissolves in forty-eight times its weight of cold water; the common carbonate requires at least ten times as much, and first forms a paste with a small quantity of the fluid. Guyton Morveau has lately found the carbonate of magnesia native, near Castel- la-Monte, in a stone considered there as a clay very rich in alumina. It is amorphous, as white as ceruse, and as compact as the hardest chalk ; does not sensibly adhere to the tongue ; and has no argillaceous smell. Its specific gravity, when all the bubbles of air it contains have escaped, is 2.612. In the fire it lost 0.585 of its weight, and became sufficiently hard to scratch Bohemian glass slightly. On analysis it was found to contain magnesia 26.3, silex 14.2, carbonic acid 46, water 12, iron an inap- preciable quantity. The carbonate of ammonia, once vulgarly VOL. i. f51 known by the name of volatile sal ammo* niac, and abroad by that of English volatile salt, because it was first prepared in this country, was commonly called mild volatile alkali, before its true nature was known. When very pure it is in a crystalline form, but seldom very regular. Its crystals are so small, that it is difficult to deter- mine their figure. Bergmann describes them as acute octaedrons, the four angles of which are truncated. Rom' de Lisle had compressed tetraedral prisms, terminated by a diedral summit. Bergmann obtained his by saturating warm water with the salt, stopping the bottle closely, and ex- posing it to great cold. The crystals com- monly produced by sublimation are little bundles of needles, or very slender prisms, so arranged as to represent herboriza- tions, 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 twice 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 alterable in the air ; but when, it lias an excess of ammonia, it softens and grows moist. It cannot be doubted, how- ever, 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 sub- limes, but does not decompose it. It has been prepared by the destructive distillation of animal substances, and some others, in large iron pots, with a fire in- creased by degrees 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 sat't of hartshorn, salt of soot, essential salt of vi- pers, &c. If the salt were dissolved in the water, it was called spirit of the substance from which it was obtained. Thus, how- ever, 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 carbonate of lime, both as dry as possible, and subliming in an earthen retort. Sir H. Davy has shown that its compo- nent parts vary, according to the manner of preparing it. The lower the tempera- ture at which it is formed, the greater the proportion of acid and water. Thus, if formed at the temperature of 300, it con- tains more than fifty per cent of alkali ; if at 60, not more than twenty per cent. * There are three or four definite com- pounds of carbonic acid and ammonia. The 1st is the solid sub-carbonate of the shops. It consists of 55 carbonic aci<3, 3Q AC1 AC1 ammonia, and 15 water; or probably of 3 primes carbonic acid, 2 ammonia, and 2 water; in all 14.76 for its equivalent. 2. But 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 con- sist by weight of 56 acid -f 43 1 alkali, being in the ratio of a prime equivalent of each. 3. When the pungent sub-carbo- nate is exposed in powder to the air, it be- comes scentless by the evaporation of a definite portion of its ammonia. It is then a compound of about 55 or 56 carbonic acid, 21.5 ammonia, and 22.5 water, (t may be represented by 2 primes of acid, 1 of ammonia, and 2 of water, = 12. 4. Ano- ther 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. Gay-Lussac infers the neutral carbonate to consist of equal volumes of the two gases, though they will not direct- ly combine in these proportions. This would give 18.1 to 46.5; the very propor- tions in the scentless salt. For 46.5 : 18.1 : : 55 : 21.42.* It is well known as a stimulant usually put into smelling-bottles, frequently with the addition of some odoriferous oil. Fourcroy has found, that an ammoniaco- magnesian carbonate is formed on some occasions. Thus, if carbonate of ammonia be decomposed by magnesia in the moist way, leaving these two substances in con- tact with each other in a bottle closely stopped, a complete decomposition will not take place, but a portion of this trisalt will be formed. The same will take place, if a solution of carbonate of magnesia in water, impregnated with carbonic acid, be precipitated by pure ammonia ; or if am- moniaco-magnesian sulphate, nitrate, or muriate, be precipitated by carbonate of potash or of soda. The properties of this triple salt are not yet \nown, but it crystallizes differently from Mae carbonate of either of its bases, and has its own laws of solubility and de- compositioo. Tlw carbonate of glucine has been ex- amined by Viviquelin, and is, among the salts of that eavth, that of which he has most accurately .ascertained the proper- ties. 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 glu- cine, but insipid. It is very light, insolu- ble in water, perfectly unalterable by the air, but very readily decomposed by fire. A saturated solution of carbonate of am- Mjonia takes up a certain portion of this carbonate, and forms with it a triple salt. Tliis property enabled Vauquelin to sepa- rate glucine from alumina, and was one of the means of his distinguishing that earth. Carbonic acid does not appear to be much disposed to unite with argillaceous earth. Most clays, however, afford a small quantity of this acid by heat; and Fourcroy says, that the fat clays effervesce with acids. The snowy white substance resembling chalk, and known by the name of lac lun can be only 0.0095, which is only the thirteenth part of the weight of an atom of hydrogen. On that supposition, fluoric acid would be composed of Inflammable basis, 1.00 Oxygen, 105.67. So very light a body, being contrary to all analogy, cannot be admitted to exist without stronger proofs than have hitherto been adduced. On the other hand, if fluor spar be in reality a fluoride of calci- um, then its composition will be, Fluorine, 2.0095 Calcium, 2.625 So that the weight of an atom of fluorine would be 2.0095, or almost exactly twice the weight of an atom of oxygen. This is surely a much more probable supposition than the former.*' It is not possible to find a more instruc- tive example than the one now afforded by this systematic chemist, of the danger of prosecuting, on slippery grounds, hy- pothetical analogies. The atom of fluoric acid, when rightly computed with his own data, is not 1.0095, but 1.3015, and hence none of his consequences need be consi- dered. It may consist of 1 of oxygen combined with 0.3015 of an unknown rad- ical ; or there may, for aught we know, be a substance analogous to chlorine and iodine, to be called therefore fluorine, whose prime equivalent' will be 2.3015. From the mode in which liquid fluoric acid is produced viz. from a mixture of fluor spar, and oil of vitriol, it may obvious- ly contain water, and may consist, as we have seen, probably of a prime or atom of j real acid, and an atom of water. Hence the phenomena occasioned by adding pot- assium to it, present nothing different from those exhibited by the same metal added to concentrated hydro-nitric or hydro-sulphuric acid. Sir H. Davy indeed i has been induced in his last researches to infer, from the action of ammoniacal gas on the liquid fluoric acid, that it contains no water. On this subject Dr. Thomson has the following aphorism : " When any acid that contains water is combined in this manner with ammoniacal gas, if we heat the salt formed, water is always disengag- ed. Thus sulphuric acid, or nitric acid, or phosphorous acid, when saturated with ammoniacal gas and heated, give out always abundance of water. But fluate of ammonia, when thus treated, gave out no water. Hence we have no evidence that fluoric acid contains any water." The whole of this reasoning is visionary. ACI It has been proved in my experimented researches on the ammoniacal salts, in- serted in the tenth volume of the Annals of Philosophy, that the sulphate and ni- trate of ammonia, in the driest state to which they can be brought by heat, short of their decomposition, contain one atom or prime equivalent of water, which is in- deed essential to their very existence, and which water cannot be separated by heat alone. If concentrated oil of vitriol be sa- turated with dry ammoniacal gas, a solid salt will be obtained, from which heat alone will not separate the proportion of water it contains, and which amounts to 13.6 percent. A stronger heat will merely separate a portion of the ammonia from the acid, or volatilize both. In the former case the acid retains its atom of water. Hence we see, that no inference whatever can be drawn from the ammoniacal com- bination with liquid fluoric acid, to nega- tive the probability that it may contain, from the mode of its extraction, combined water, like the sulphuric and nitric acids. The inferences from the analogous ac- tions of potassium on the muriate and fluate of ammonia, are all liable to the same fallacy. If the combined water of the fluoric acid pass into the salt, as with sulphuric acid it undoubtedly does, then hydrogen and fluate of potash ought to result, from the joint actions of potassium and the hydro-fiuoric acid. The chocolate powder which is evolved at the positive pole, and the hydrogen at the negative, when liquid fluoric acid was subjected by Sir H. Davy to the voltaic power, can justify no decisive opinion on this intricate research. The mere coating of the platinum wire may as well be re- garded as the fluate of platinum, as a fluor- ide. Nor does the decomposition of the fluates of silver and mercury, when heated in glass vessels with chlorine, seem to prove any thing whatever. The oxygen evolved, is obviously separated from the oxides of silver or mercury when acted on by chlorine ; and the dry fluoric acid unites to the silica of the glass, forming- silicated fluoric gas, or fluo-silicic acid. [n thus showing the inconclusiveness of Dr. Thomson's four different arguments, to prove that fluoric acid is a compound of an unknown radical, fluorine, with hydro- gen, and not of an unknown radical, which might be termed fluor, with oxygen ; one cannot help, however, expressing a high admiration of Sir H. Davy's experimental researches on fluoric acid, which were published in the second part of the Phil- osophical Transactions for 1813. He did all which the existing resources of science could enable genius and judgment to ac- complish. The mystery in which the subject obvionsly and confessedly remains. ACI ACI must be removed by further investigations, and not by analogical assumptions. These, indeed, by giving resting points to the imagination, of which it becomes found, powerfully tend to obstruct the advance- ment of truth. The principal reason for considering fluoric acid as a compound of fluorine with hydrogen, seems on the whole to be the analogy of chlorine. But the analogy is in- complete. Certainly it is consonant to the true logic of chemical science to regard chlorine as a simple body, since ^'ery at- tempt to resolve it into simpler forms of matter has failed. But fluorine has not been exhibi'ed in an insulated state like chlorine ; and here therefore the analogy does not hold. With the view of separating its hydro- yen, Sir H, Davy applied the power of the great voltaic batteries of the royal Institu- tion to the liquid fluoric acid. " In this case, gas appeared to be produced from both the negative and positive surfaces; but it was probably only the undecom- pounded acid rendered 'gaseous, which was evolved at the positive surface ; for during the operation the fluid became very hot, and speedly 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 decom- posed when passed through a platinatube heated red hot with chlorine, nor by being distilled from salts containing abundance of oxygen, or those containing abundance of chlorine." By the strict rules of chem- ical logic, therefore, fluoric acid ought to be regarded as a simple body, for we have no evidence of its ever haviag been de- composed ; and nothing but analogy with the other acid bodies has given rise to the assumption of its being a compound. There is no difficulty in imagining a radical to exist, whose saturating powers are exactly one-third of those of hydrogen; for 0.375' is precisely thrice 0.125, the weight of the prime equivalent of hydro- gen; and one-half of 0.750, the equivalent of carbon. Those who are allured by the harmony of numbers, might possibly con- sider these examples of accordance, as of some value in the discussion. The marvellous activity of fluoric acid may be inferred from the following- re- marks of Sir H. Davy, from which also may be estimated in some measure the prodigious difficulty attending refined in- vestigations on this extraordinary sub- stance. " I undertook the experiment of elec- trizing pure liquid fluoric acid with con- siderable interest, 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 immediately destroys glass, and all animal and vegetable sub- stances ; it acts on all bodies contain- ing metallic oxides ; and 1 know of no sub- stances which are not rapidly dissolved or decomposed by it, except metals, char- coal, phosphorus, sulphur, and certain combinations of chlorine. 1 attempted to make tubes of sulphur, of muriates of lead and of cop per containing metallic wires, by which it might be electrized, but with- out success. I succeeded, however, in bor- ing a piece of horn silver in such a man- ner 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 elec- tricity in such a manner, tha% in succes- sive experiments, it was possible to col- lect any elastic fluid that might be pro- duced Operating in this way with a very weak voltaic power, and keeping the apparatus cool by a freezing mixture I ascertained that the pla ina wire at the positive pole rapidly corroded, and be- came covered with a chocolate powder; gaseous matter separated at the negative pole, which I could never obtain in suffi- cient 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 Tilloch's Magazine, where he will see philosophical sagacity and experimen- tal skill in their utmost variety and vigour, struggling with the most mysterious and intractable powers of matter 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 mer- cury. The best mode of pi-ocuring 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 obtained in greater quantities. This gas, which is called sili- cated fluoric gas, is possessed of very ex- traordinary 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 3.6 32 is to 1.000. It is about 48 times denser than hydrogen. When brought into contact with water, it instantly deposites a white gelatinous sub- stance, which is hydrate of silica ; it pro- duces white fumes when suffered to pass into the atmosphere. It is not affected by any of the common combustible bodies; ACI ACI feut when potassium is strongly heated in it, it takes fire and burns with a deep red fight ; the gas is absorbed, and a fawn-co- loured substance is formed, which yields alkali to water with slight effervescence, and contains a combustible body. The washings afford potash and a salt, from which the strong acid fluid previously de- scribed, 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 supposed by Sir H. Da- vy to consist of two prime proportions of acid = 2.652 and one of silica = 4. 066, the sum of which numbers may represent its equivalent = 6.718. One volume of it con- denses 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 1 prime of ammonia to 1 of the fluosilicic gas ; for 200 cubic inches of am- monia weigh 36. 2 gr. and 100 of the acid gas 110.77. Now 36.2 : 2.13 : : 110.77 : 6.52. Dr. John Davy obtained, by exposing this gas to the action of water,-^^. of its weight of silica ; and from the action of water of ammonia he separated - 6 ~*~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, conceives that this gas is a compound of the basis of silica, or silicon, with fluorine, the supposed basis of fluoric acid. If, instead of glass or silica, the fluor spar be mixed with dry vitreous boracic acid, and distilled in a glass vessel with sulphu- ric acid, the proportions being one part boracic acid, two fluor spar, and twelve oil of vitriol, the gaseous substance formed is of a different kind, and is called thefluo- boric gas. 100 cubic inches of it weigh 73.5 gr. according to Sir H. Davy, which makes its density to that of air as 2.41 is to 1.00; but M. Thenard, from 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 muriatic acid; it cannot be breathed without suf- focation ; it extinguishes combustion ; and reddens strongly the tincture of turnsole. It has no manner of action on glass ; but a very powerful one on vegetable and ani- mal matter: It attacks them with as much force as concentrated sulphuric acid, and Appears to operate on these bodies by Voi. i. [ 6 ] the production of water; for while it cat* bonizesthem, or evolves carbon, they may be touched without any risk of burning. Exposed to a high temperature, it is not decomposed; it is condensed by cold without 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, [t becomes in consequence a liquid which emits extremely dense va- pours 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 va- pours. It may hence be employed with ad- vantage to show whether or not a gas con- tains moisture. No combustible body, simple or com- pound, attacks fluoboric gas, if we except the alkaline metals. Potassium and sodi- um 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 in- ferred 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. Da- vy'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 re- mains disengaged. Fluoboric gas is very soluble in water; Dr. John Davy savs, 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 spe- cific gravity of 1.770. If a bottle contain- ing this gas be uncorked under 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 sul- phuric acid, and boils at a temperature considerably above 212. It afterwards condenses altogether, in stricc, although it contains still a very large quantity of gas. It unites with the bases, forming salts, call- ed fluoborates, none of which has been applied to any use. The most important will be described under their respective bases. 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 pulverulent salt is form- ed; a second volume of ammonia, howev- er, gives a liquid compound; and a third of ammonia, which is the limit of combi- ACI ACI of "about 68 F. was reduced from 103 grains to 91, and rendered white through- out. Some parts of it were rendered fria- ble. White Carrara marble in twenty four hours, at 77, lost l-30th of its weight, but the shining surface of its crystallized tex- affords still a liquid; both of them with efflorescent white spots, and partly curious on many accounts. " They are," covered with the common white crust, be- says he, " the first salts that have been ob- ing exposed five days to the gas at a heat served liquid at the common temperature of the atmosphere. And they are addition- al facts in support of the doctrine of defi- nite proportions, and of the relation of vol- umes." The fluosilicic acid also unites to bases forming fluos-.licates. If we regard fluoric acid as capable of ture was distinguishable. Black marble combining, like the sulphuric, nitric, and was not affected, either in weight or co- carbonic acids, with the oxidized bases, lour, and agate was not attacked. Trans- the weight of its prime equivalent is^.. 375; parent foliated gypsum fell into white whence all its neutral compounds may be powder on its surface, in a few hours ; but inferred ; but if we suppose that it is fluo- this powder was not soluble in dilute ni- tric acid, so that the fluoric acid had not destroyed the combination of its princi- ples ; but deprived it of its water of crys- tallization. A striated zeolite, weighing nne alone which unites to the metallic bases, then the prime of oxygen must be subtracted from them and added to its weight, which will make it 2.375. This is exactly like a man taking a piece of money out of the one pocket, anl putting it in 102 grains, was rendered friable on its sur- face in forty-eight hours, and weighed only the other. All the proper ions experimen- 85| grains. On being immersed in water, tally associated with the compound, re main essentially the same.* and then dried, it gained 2 grains, but did not recover its lustre. Barvtes of a fi- From the remarkable property fluoric brous texture remained unchanged. A thin, acid possesses of corroding glass, it has plate of Venetian talc, weighing 124 gr. been employed for etching on it, both in was reduced to 81 grains in forty-eight the gaseous state and combined with wa- hours, and had fallen into a soft powder, ter; and an ingenious apparatus for this which floated on water. M. Kortum pour- purpose is given by Mr. Richard Knight, ed water on the residuum in the appara- in the Philosophical Magazine, vol. xvii. p. tus, and the next day the sides were in- 357. crusted with small crystalline glittering M. Kortum, of Warsaw, having found flakes, adhering in detached masses, which that some pieces of glass were more easily could not be washed off with dilute ni- acted upon by it than others, tried its ef- trous acid. feet on various stones. Rock cr\ stal, ruby. Of the combinations of this acid with sapphire, lux sapphire, emerald, oriental most of the bases little is known, garnet, amethyst, chrysolite, aventurine, The native fluate of lime, the fluor spar cirasol, a Saxon topaz, a Brazilian topaz already mentioned, is the most common burnt, and an opal, being exposed to the fluoric gas at a temperature of 122 F was not acted upon. Diamond exposed to the vapour on a common German stove for four days, was unaffected. Of polished granite, neither the quarts nor mica ap- peared to be attacked, but the feldspar was rendered opaque and muddy, and co- vered with a white powder. Chrysoprase. It is rendered phosphorescent by heat, but this property gradually goes off, and can- not be produced a second time. With a strong heat it decrepitates. At a heat of 130 'of Wedgwood, it enters into fusion in a clay crucible. It is not acted upon by the air,* and is insoluble in water. Concen- trated sulphuric acid deprives it of the flu- oric acid with effervescence, at the com- an opal from Hungary, onyx, a carnelian mon temperature, but heat promotes its rf *- _ 1 " 1 1 __C1* .- n -1 *j__ _ _j_ * *.\^ *~ from Persia, agate, chalcedony, green Si- berian jasper, and common flint, were etched by it in twenty-four hours ; the chrysoprase near half a line deep, the onyx pretty deeply, the opal with the finest and most regular strokes, and all the rest more or less irregularly. The un- covered part of the b"o\vn flint had be- come white, but was still compact : water, alcohol, and other liquids, rendered the whiteness invisible, but as soon as the flint became dry, it appeared again. The same effect was produced on carnelian, and on action. Besides its use for obtaining this acid, it is much employed in chimney or- naments, and as a flux for some ores and stones. The fluoric acid takes barytes from the nitric and muriatic, and forms a salt very little soluble, that effloresces in the air. With magnesia, it precipitates, accord- ing to Scheele, in a gelatinous mass. But Bergmann says, that a part remains in so- lution, and by spontaneous evaporation, shoots on the sides of the vessel into crys- talline threads, resembling a transparent a dark brown jasper, if the operation of mass. The bottom of the vessel affords al- the acid were stopped, as soon as it had so crystals in hexagonal prisms, ending in whitened the part exposed, without de- a low pyramid of three rhombs. He adds, stroying- its texture. A piece of black flint, that no acid decomposes it in the moist ACI ACI Way, and that it is unalterable by the most violent fire. The fluate of potash is not crystalliza- ble ; and if it be evaporated to dryness, it soon deliquesces. Its taste is somewhat acrid and saline. It melts with a strong heat, is afterward caustic, and attracts moisture. This fluate, as well as those of soda and ammonia, are commonly obtained, as Four- croy conceives, in the state of triple sails, being combined with siliceous earth. The fluate of soda affords small crystals in cubes and parallelograms, of a bitterish and astringent taste, decrepitating on burn- ing coals, and melting into semitransparent globules with the blowpipe, without losing their acid. It is not deliquescent, and dif- ficultly soluble. The concentrated acids disengage its acid with effervesence. The fluate of ammonia may be prepared By adding carbonate of ammonia to diluted fluoric acid in a leaden vessel, observing, that there is a small excess of acid. This is a very delicate test of lime. Fourcroy informs us, that ammonia and magnesia form a triple salt with the fluoric acid. Scheele observed, that the fluor acid united with alumina into a salt that could not be crystallized, but assumed a gela- tinous form. Fourcroy adds, that the solu- tion is always acid, astringent, decompo- sable and precipitabie by all the earthy and alkaline bases, but capable of uniting with silex and the alkalis into various triple salts. A native combination of alumina and soda with fluoric acid, has been found late- ly in a semitransparent stone from Green- land. See CRYOLITE. The affinity of the fluoric acid for silex, has already appeared. If the acid solution of fluate of silex, obtained by keeping the solution of the acid in glass vessels, be evaporated to dryness, the fluoric acid may be disengaged from the solid salt remain- ing, as Fourcroy informs us, either by the powerful acids, or by a strong heat ; and if the solution be kept in a vessel that ad- mits of a slow evaporation, small brilliant crystals, transparent, hard, and apparently of a rhomboidal figure, will form on the bottom of the vessel, as Bergmann found in the course of two years' standing. Besides the fluor spar and cryolite, in which it is abundant, fluoric acid has been detected in the topaz ; in wavellite, in which, however, it is not rendered sensi- ble by sulphuric acid ; and in fossil teeth and fossil ivory, though it is not found in cither of these in their natural state. ACIDS (FERROPRUSSIC and FKRRUBETTED CHTAZIC). See ACID (Paussic). ACID (FORMIC). It has longbeen known, that ants contain a strong acid, which they occasionally emit ; and which may be ob- tained from the ants, either by simple dis- tillation, or by infusion of them in boiling water, and subsequent distillation of as much of the water as can be brought over without burning the residue. After this it may be purified by repeated rectifications, or by boiling to separate the impurities ; or after rectification it may be concentrated by frost. * This acid has a very sour taste, *nd continues liquid even at very low temper- atures. Its specific gravity is 1.1 168 at 68, which is much denser than acetic acid ever is. Berzelius 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 hydrogen 2.84 -{- car- bon 32.40 -f oxygen 64.76 = 100.* We have been informed, that it has been employed among quacks, as a wonderful remedy for the toothach, by applying it to the tooth with the points of the forefinger and thumb. * ACID (FUNGIC). The expressed juice of the boletus juglandis, boletus pseiido-igni- arius, the phallus impudicus, merulius can- tharellus, or the pepiza nigra, being boiled to coagulate the albumen, then filtered, evaporated to the consistence of an ex- tract, and acted on by pure alcohol, leaves a substance which has been called by Braconnot Fungic Jlcid. He dissolves that residue in water, added solution of acetate of lead, whence resulted fungate of lead, which he decomposed at a gentle heat by dilute sulphuric acid. The evolved fun- gic acid being saturated with ammonia, yielded a crystallized fungate of ammonia, which he purified by repeated solution and crystallization. From this salt by ace- tate of lead, and thereafter sulphuric acid as above detailed, he procured the pure fungicacid. It is a colourless, uncrystallizable, and deliquescent mass, of a very sour taste. The fungates of potash and soda, are un- crystallizable ; that of ammonia forms re- gular 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 pre- cipitates from the acetate of lead a white flocculent fungate, which is soluble in dis- tilled 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 vegetable substances possessing astringent properties, but most abundant- ly in the excrescences termed galls, or nut- galls, whence it derives its name. It may be obtained by macerating galls in water, filtering, and suffering the liquor to stand exposed to the air. It will grow mouldy, AUI ACI be covered with a thick glutinous pellicle, abundance of glutinous flocks will full down, and, in the course of two or three months, the sides of the vessel will appear covered with small yellowish crystals, abundance of which will likewise be found on the under surface of the supernatant pellicle. These crystals may be purified by solution in alcohol, and evaporation to dryness. Or muriate of tin may be added to the infusion of galls, till no more precipitate falls down ; the excess of oxide o^tin re- maining in the solution, may then be pre- cipitated by sulphuretted hydrogen gas, and the liquor will yield crystals of gallic acid by evaporation. A more simple process, however, is that of M. Fiedler. Boil an ounce of powdered galls in sixteen ounces of water to eight, and strain. Dissolve two ounces of alum in water, precipitate the alumina by car- bonate of potash ; and, after edulcorating it completely by repeated ablutions, add it to the decoction, frequently stirring the mixture with a glass rod. The next day filter the mixture ; wash the precipitate with warm water, till this will no longer blacken sulphate of iron ; mix the wash- ings with the filtered liquor, evaporate, and the gallic acid will be obtained in fine needled crystals. These crystals obtained in any of these ways, however, according to Sir H. Davy, are contaminated with a small portion of extractive matter ; and to purify them they may be placed in a glass capsule in a sand heat, and sublimed into another capsule, inverted over this and kept cool. M. De- yeux indeed recommends to procure the acid by sublimation in the first instance ; putting the powdered galls into a glass retort, and applying heat slowly and cau- tiously ; when the acid will rise, and be condensed in the neck of the retort. This process requires great care, as, if the heat be earned so far as to disengage the oil, the crystals will be dissolved immediately. The crystals thus obtained are pretty large, laminated, and brilliant. The gallic acid, placed on a red-hot iron, burns with flame, and emits an aro- matic smell, not unlike that of benzole acid. It is soluble in 20 parts of cold water, and in 3 parts at a boiling heat. It is more so- luble in 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 at- tract humidity 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 4- carbon 56 64 + oxygen 38.36 = 100. This acid, in its combinations with the salifiable bases, presents some remarkable phenomena. If we pour its aqueous solu- tion by slow degrees into lime, bar) tes, or strontian water, there will first be formed a greenish white precipitate. As the quan- tity 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 decom> poses almost all the salts of the permanent metals.* Concentrated sulphuric acid decompo- ses and carbonizes it ; and the nitric acid converts it into malic and oxalic acids. United with barytes, strontian, lime, and magnesia, it forms salts of a dull yellow colour, which are little soluble, but mora so if their base be in excess. With alkalis, it forms salts that are not very soluble in general. 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 metallic oxides part with their oxy- gen, the more they are alterable by the gallic acid. To a solution of gold, it im- parts a green hue ; and a brown precipi- tate is formed, which readily passes to the metallic state, and covers the solution with a shining golden pellicle. With ni- tric solution of silver, it produces a similar effect. Mercury it precipitates of an orange yellow ; copper, brown ; bismuth, of a le- mon colour; lead, white; iron, black. Pla- tina, zinc, tin, cobalt, and manganese, are not precipitated by it. 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 ingredient in ink. See GALLS, DYE- ING and IKK. * ACID (HYDROCYANIC). See ACID (Pnussic). * ACID (HvDTuoDic). This acid resem- bles the muriatic in being gaseous in its insulated state. If four parts of iodine be mixed with one of phosphorus, in a small glass retort, applying a gentle heat, and adding a few drops of water from time to time, a gas comes over, which must be received in the mercurial bath. Its spe- cific gravity is 4.4; 100 cubic inches, therefore, weigh 134 2 grains. It is elas- tic and invisible, but has a smell some- what similar to that of muriatic acid. Mer- cury after some time decomposes it, seiz- ing its iodine, and leaving its hydrogen equal to one-half the original bulk, at li ACI AC1 berty. 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 combine in equal vo- lumes, without change of their primitive bulk. Us composition by weight, is there- fore 8.61 of iodine -f 0.0694 hydrogen, which is the relation of their gasiform densities; 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 equivalent of hydriodic acid. The number deduced for iodine, from the relation of iodine to hydrogen in Volume, approaches very nearly to 15.621, which was obtained in the other experi- ments 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 separated. M. Gay-Lussac, in his admirable memoir n iodine and its combinations, published in the Ann. de Chimie, vol. xci. says, that the specific gravity he there gives for hy- driodic 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 oxy- gen, whose specific gravity is 1.1111; and multiply one-half of this number by 15 621, as he does, we shall have a pro- duct of 8.6696, to which adding 0.0694 for the density of hydrogen, we get the sum 8.7390, one-half of which is obvious- ly the density of the hydriodic gas = 4.3695. When the prime of iodine is ta- ken at 15.5, then the density of the gas comes out 4.3. We can easily obtain an aqueous hy- driodic acid very economically, by pass- ing 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 temperatures below 262, it parts with its water ; and becomes of a density = 1.7. At 262 the acid 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 perexide of mercury, it gives a red precipitate ; and with that of silver, a white precipitate insoluble in am- monia. Hydriodic acid may also be form- ed, by passing hydrogen over iodine at an elevated temperature. The compounds of hydriodic acid with the salifiable bases may be easily fortnecl, either by direct combination, or by acting on the basis in water, with iodine. The latter mode is most economical. Upon a determinate quantity of iodine, pour solu- tion of potash or soda, till the liquid ceases to be coloured. Evaporate 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. Af- ter having washed the iodate two or three times with alcohol, dissolve it in water, and neutralize it with acetic acid. Eva- porate 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 hydrio- date, 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 tempera- ture of the air. Chlorine, nitric acid, and concentrated sulphuric, 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 precipitate ; with corrosive sublimate, a precipitate of a fine orange red, very so- luble 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 64, dissolve 143 of it. It con- sists of 15.5 iodine, and 4.95 potassium. Hydriodate of soda, called in the dry state iodide of sodium, may be obtained in pretty large flatrhomboidal prisms. These prisms unite together with larger ones, terminated in echellon, and striated long- ways, 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- 2 '95 so- dium. Hydnodate ofbarytes crystallizes in fine prisms, similar to muriate of strontian. In its dry state, it consists of 15.5 iodine -\-. 8.7 or 8.75 barium. The hydriodates of lime and strontian are very soluble; and the first exceedingly deliquescent. Hydnodate of ammonia results from the combination of equal volumes of ammonia- cal and hydriodic gases ; though it is usual- ly prepared by saturating the liquid acid ACI ACI with ammonia. It is nearly as volatile as gal ammoniac ; 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 am- monia, to a prime of hydriodic acid, so is the density of ammoniacal, to that of hy- driodic gas. 2.13 : 15.625 : : 0.59 : 4.32* This would make 100 cubic inches weigh exactly 132 grains. Hydriodate of magnesia is formed by unit- ing its constituents together; it is deli- quescent, and crystallizes with difficulty. It is decomposed by a strong heat. Hydriodate of zinc is easily obtained, by putting iodine into water with an excess of zinc, and favouring 1 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.* * ACID (IOTHC). When barytes water is made to act on iodine, a soluble hydrio- date, and an insoluble iodate of barytes, are formed. On the latter, well washed, pour sulphuric acid equivalent to the ba- rytes 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; fmt though even less than the equivalent 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 first discoverer of this acid, invented one more elegant, and which yields a purer acid. Into a long glass tube, bent like the letter L inverted ( r j), 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. Pro- toxide of chlorine is evolved, which, as it comes in contact with the iodine, pro- duces combustion, and two new com- pounds, a compound of iodine and oxy- gen, and one of iodine and chlorine. The latter is easily separable by heat, while the former remains in a state of purity. The iodic acid of Sir H, Davy is a white semi-transparent solid. It has a strong acido-as'ringent tas'e, 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 quantities ; and must therefore excite ad- miration at the precision of result derived by sir H. from the very minute proper- tions which he used. 176.1 grain mea- sures, are equal to 0.7 of a cubic inch; winch, calling 100 cubic inches 33.88, will weigh 237 of a g.ain, leaving 0.763 for iodine. And 0.763 .- 0.2 .>7 : : 15.5 : 5.0. Iodic acid deliquesces in the air, and is, of course, very soluble in \vaer. It first reddens, and then destroys the blues of vegetable infusions. It blanches other ve- getable colours. By concen ration of the liquid acid of Gay-Lussac, it acquires the consistence of sirup. Had not the happy genius of Sir H. Davy produced it in the solid state, his celebrated French rival would have persuaded us to suppose that slate impossible. " Hitherto, 5 ' says M. Gay-Lussac, "iodic acid has only been obtained in combination with water and it is very probable that this liquid is as necessary as a base, to keep the elements of this acic. united, as we see is the case with sulphuric acid, nitric acid," 8tc. M. Gay-Lussac's Memoir was read to the Institute on the 1st August 1814 ; and, on the 10th February following, Sir H. dates at Rome his communication to the Uo} al Society, written before he had seen the French paper. When the temperature of inspissated iodic acid is raised to about 392, it is resolved into iodine and oxygen. Here we see the influence of water is ex- actly the reverse of what M. Gay-Lussac assigns to it; for, instead of giving fixity like a base to the acid, it favours its de- composition. The dry acid may be raised to upwards of 600 y without being decom- posed. Sulphurous acid, and sulphuret- ted 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, 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 fulmin- ates when heated. Between the acid prepared by M. Gay-Lussac, and that of Sir H. Davy, there is one important dif- ference. The latter being dissolved, may, by evaporation of the, water, pass not only ACT ACI the inspissated sirupy state, but can made to assume a pasty consistence ; ind finally, by a stronger heat, yields the solid substance unaltered. When a mix- :ure of it, with charcoal, sulphur, rosin, sugar, or the combusrible metals, in a finely divided state, is heated, detonations are produced; and its solution rapidly [corrodes all the metals to which Sir H. Davv 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 decompose. When sulphuric acid is drop- ped into a concentra.ed solution of it in hot water, a solid substance is precipita- ted, which consists of the acids in com- I bination ; for, on evaporating the s lu- tion by a gentle heat, nothing rises but i water. On increasing the heat in an ex- penment of this kind, the solid substance formed fused ; and on cooling the mixture, rhomboidal cr-stals formed of a pale yel- low colour, which were very fusible, and which did not change at the heat at which the compound of oxygen and iodine de- composes, but sublimed unaltered. When urged by a much stronger heat, it par- tiall sublimed and partially decomposed, affording oxygen, iodine, and sulphuric acid. With hydro phosphoric, the compound presents phenomena precisely similar, and they form together a solid, yellow, crys- talline combination. With hydro-nitric acid, it yields white crystals in rhomboidal plates, which, at a lower heat than the preceding acid com- pounds, are resolved into hydro-nitric acid, oxygen, and iodine. By liquid mu- riatic acid, the substance is immediately decomposed, and the compound of chlo- 'jine and iodine is formed. All these acid compounds redden vegetable blues, taste sour, and dissolve gold and platinum. 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 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 already described the method of forming the iodates, a class of salts distinguished chiefly for their property of deflagrating when heated with combustibles.* *Acin (CHLORTODTC). The discovery of this interesting compound, constitutes an- other of Sir H. Davy's contributions to the advancement of science. In a communi- cation from Florence to the Royal Socie- ty, in March 1814, he gives a curious de tail of its preparation and properties. He formed it, by admitting chlorine in excess to known quantities of iodine, in vessels exhausted of air, and repeatedly 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 sub- stance, and in consequence of its action upon mercury, he was not able to deter- mine the elastic force of its vapour. In the most considerable experiment which he made to determine proportions, 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 num. ber certainly not far from 4.5, the prime equivalent of chlorine ; and in the very delicate circumstances of the experiment, an approximation 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 15.5, the prime equivalent of iodine. The chloriodic acid formed by the sub- limation of iodine in a great excess of chlorine, is of a bright yellow colour; when fused it becomes 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 becomes, in consequence, deeper, and the chloriodio acid and the iodine rise together in the elastic state. The solution of the chlo- riodic acid in water, likewise dissolves large quantities of iodine, so that it is pos- sible to obtain a fluid containing very dif- ferent proportions of iodine and chlorine. When two bodies so similar in their characters, and in the compounds they form as iodine and chlorine, act upon sub- stances at the same time, it is difficult, Sip H. observes, to form a judgment of the different parts that they play in the new- chemical arrangement produced. It ap- pears most probable, that the acid pro- perty of the chloriodic compound de- pends upon the combination of the two bodies ; and its action upon solutions of the alkalis and earths may be easily ex- plained, when it is considered that chlo- rine has a greater tendency than iodine to form double compounds with the metals, and that iodine has a greater tendency 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 brea4 ACI ACI snaked with water, holding some of it in solution, that it is not poisonous like iodine itself.* ACID (HrDROTHiowic). Some of the German chemists distinguish sulphuretted hydrogen by this name, on account of its properties resembling those of an acid. * Acm (Kimc). 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 re- moves the resinous part of this ^xtract, and leaves a viscid residue, of a brown co- lour, which has hardly any bitter taste, and which consists of kinite of lime and a mucilaginous matter. This residue is dis- solved in water, the liquor is filtered and left to spontaneous evaporation, in a warm place. It becomes thick like sirup, and then deposites by degrees crystalline plates, sometimes hexahedral, sometimes rhomboidal, sometimes square, and al- ways coloured slightly of a reddish brown. These plates of kinate of lime must be pu- rified by a second crystallization. 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 spon- taneous evaporation, yields regular crys- tals. It is decomposed by heat. While it forms a soluble salt with lime, it does not precipitate lead or silver from their solu- tions. These are characters sufficiently distinctive. The kinates are scarcely known ; that of lime constitutes 7 per cent ef cinchona.* ACZD (LACCIC) of Dr. John. * This chemist made a watery extract of powdered stick lac, and evaporated it to dryness. He digested alcohol on this extract, and evaporated the alcoholic ex- tract to dryness. He then digested this mass in ether, and evaporated the etlierial solution ; when he obtained a sirupy mass of a light yellow colour, which was again dissolved in alcohol. On adding water to this solution a little resin fell. A peculiar acid united to potash and lime remains in the solution, which is obtained free, by forming with acetate of lead an insoluble laccate, and decomposing this with the equivalent quantity of sulphuric acid. Laccic acid crystallizes; it has a wine yel- low 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 not affect lime, barytes, or sil- ver, 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). Ey evaporating sour whey to one-eighth, filtering, precipitating with lime-water, and separating the lime by oxalic acid, Scheele obtained an aqueous solution of what he supposed to be a peculiar acid, which has accordingly been termed the lactic. To procure it separate, he evaporated the solution to the consistence of honey, poured on it al- cohol, filtered this solution, and evapora- ted the alcohol. The residuum was an acid of a yellow colour, incapable of being crystallized, attracting the humidity of the air, and forming deliquescent salts with the earths and alkalis. Bouillon Lagrange since examined it more narrowly ; and from a series of ex- periments concluded, that it consists of acetic acid, muriate of potash, a small por- tion of iron probably dissolved in the ace tic acid, and an animal matter. * This judgment of M. Lagrange was afterwards supported by the opinions of MM. Fourcroy and Vauquelin. But since then Berzelius has investigated its nature very fully, and has obtained, by means of a long and often repeated series of differ- ent experiments, a complete conviction that Scheele was in the right, and that the lactic acid is a peculiar acid, very dis- tinct from all others. The extract which is obtained when dried whey is digested with alcohol, contains uncombined lactic acid, lactate of potash, muriate of potash, and a proper animal matter. As the elimi- nation of the acid affords an instructive example of chemical research, we shall present it at some detail, from the 2d vo- lume of Berzelius's Animal Chemistry. He mixed the above alcoholic solution with another portion of alcohol, to which 7 J _ of concentrated sulphuric acid had been added, and continued to add fresh por- tions 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 precipitated, and! there remained in the alcohol, muriatic acid, lactic acid, sulphuric acid, and a mi- nute portion of phosphoric acid, detached from some bone earth which had been held in solution. The acid liquor was filtered, and afterwards digested with car- bonate of lead, which with the lactic acid affords a salt soluble in alcohol. As soon as the mixture had acquired a sweetish taste, the three mineral acids had fallen down in combination with the lead, and the lactic acid remained behind, imper- fectly saturated by a portion of it, from which it was detached by means of sul- phuretted hydrogen, and then evaporated to the consistence of o 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 itwith a mixture of a large quantity ACI ACI I: Of fresh lime and water, so that the ani- I mal substances were precipitated and de- I stroyed by the lime. The lime became I yellow brown, and the solution almost colourless, while the mass emitted a smell of soap lees, which disappeared as the boijing was continued. The fluid thus obtained was filtered and evaporated, until a great part of the superfluous lime held in solution was precipitated. A small por- tion of it was then decomposed by oxalic acid, and carbonate of silver was dissolved in the uncombined lactic acid, until it was fully saturated. With the assistance of the lactate of silver thus obtained, a further quantity of muriatic acid was separated from the lactate of lime, which 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 precipitate. It was then evaporated to dryness, and dis- solved 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 longer fluid while warm ; it be- came a brown clear transparent acid, which was the lactic acid, free from all substances that we have hitherto had reason to think likely to contaminate it. The lactic acid, thus purified, has a brown yellow colour, and a sharp sour taste, which is much weakened by dilu- ting 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 crystal- lize, and does not exhibit the slightest ap- pearance 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 extreme- ly distinct from that of the acetic acid ; afterwards it is charred, and has an empy- reumatic, but by no means an animal smell. A porous charcoal is left behind, which does not readily burn to ashes. When distilled, it gives an empyreumatic oil, water, empyreumatic vinegar, carbon- ic acid, and inflammable gases. With alkalis, earths, and metallic oxides, it af- fords peculiar salts : and these are distin- guished by being soluble in alcohol, and in general by not having the least disposi- tion to crystallize, but drying into amass like gum, which slowly becomes moist in the air. Lactate of potash is obtained, when the lactate of lime, purified as has been men- tioned, is mixed warm with a warm solu- tion of carbonate of potash. It forms, in drying, a gummy, light vellmv brown, Voi. T. [71 transparent mass, which cannot easily be made hard. If it is mixed with concentra- ted sulphuric acid, no smell ot acetic acid is perceived ; but if the mixture is heated, it acquires a disagreeable pungent smell, which is observable in all animal substan- ces mixed with the sulphuric acid. The extract which is obtained direct;y from milk, contains this salt ; but this affords, when mixed with sulphuric 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 modifi- cation into the smell of almost all organic bodies. The pure lactate of potash is easily soluble in alcohol ; that which contains au 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 requires 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 potash, and can only be distinguished from it by analysis. Lactate of ammonia. If concentrated lactic aoid is saturated with caustic am- monia in excess, 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 tendency 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 contains 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 evapo- ration an almost colourless gummy mass, which hardens into a stiff' but not a brittle varnish. It does not show the least tenden- cy 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 be- comes more soluble. The lactate of lime is obtained in the manner above described. It affords a gummy mass, \rhichis also divided by alco- hol into two portions. 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 lactate of lime. That which is insoluble in alcohol is AC1 ACI a powder, with excess of the base ; re- ceived on a filter, it becomes smooth in the aif like gum, or like malate of lime. By boiling with more lime, and by the precipitation of the superfluous base upon exposure to the air, it becomes pure and soluble in alcohol. Lactate of magnesia, evaporated to the consistence of a thin sirup, and leit in a warm place, shoots into small granular crystals. When hastily evaporated to dryness, it affords a gummy mass. With regard to alcohol, its properties resemble those of the two preceding salts. The lactate of lead may be obtained in several different degrees of saturation. If the lactic acid is digested with the carbon- ate of lead, it becomes browner than be- fore, but cannot be fully saturated with the oxide ; and we obtain an acid salt, which does not crystallize, but dries into a sirup-like brown mass, with a sweet austere taste. When a solution of lactic acid in alcohol is digested with finely pow- dered litharge, until the solution becomes sweet, and is then slowly evaporated to the consistence of honey, the neutral lac- tate of lead crystallizes in small grayish Jlmmoniaco-muffnesian lactate is obtained grains, which may be rinsed with alcohol, by mixing- the preceding salt with caustic ammonia, as long as any precipitation con- tinues. By spontaneous evaporation this salt shoots into needle-shaped prisms, which are little coloured, and do not change in the air. Berzelius has once seen these crystals form in the alcoholic to wash off the viscid mass that adheres to them, and will then appear as a gray granu* lar salt, which when dry is light and silvery. This silver grained salt is not changed in the air ; treated with sulphuretted hy- drogen it affords pure lactic acid. If the extract of milk boiled to dryness; but lactic acid is digested with a greater por this is by no means a common occur rence. The lactate of silver is procured by dis- solving 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 exter- nally an unusual splendour like that of a looking-glass. If the evaporation is con- ducted in a deeper vessel, and with a stronger he?it, a part of the salt is decom- posed, and remains brown from the reduc i* j_i_ _ _*i i / % A i_ _ __ij_ iv i __ tion of levigated litharge 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 evapo- rated, and water is then poured on the dry mass, a very small portion of it only is dissolved ; the solution 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 tion of the silver. If this salt is dissolved hot. a great part of that which had been 'J l_ 1 _ . a.* _*.! T 1 *~ 1 '11 1 ' * j j. 1 ___l.!1_ "A. in water, no inconsiderable portion of the silver is reduced and deposited, even when the salt has been transparent ; and the concentrated solution has a fine green- ish yellow colour, which by dilution be- comes yellow. If we dissolve the oxide of silver in an impure acid, the salt be- comes 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 evapora- tion. The salt exhibits acid properties, deliquesces in the air, and is partially dis- solved in alcohol, but is at the same time dissolved will be precipitated while it cools, in the form of a white, or light yellow powder, which is a sublactate of lead. This salt is of a light flame colour; when dried, it remains mealy, and soft to the touch, and it is decomposed by the weak- est 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 tin- der, and leaves the lead in great measure reduced. A hundred parts of this saltj dissolved in nitric acid, and precipitated with carbonate of potash, gave exactly decomposed and deposites carbonate of 100 parts of carbonate of lead; conseq mercury, while the mixture acquires slight smell of ether. The lactic acid dis- solves also the red oxide of mercury, and gives with it a red gummy deliquescent salt. If it is left exposed to a warm and moist atmosphere, it deposites, afterthe ex- piration of some weeks, a light semi-crys- talline powder, which he has not examin- uent ly its component parts, determined frorr. those of the carbonate, must be 83 of the oxide of lead, and 17 of the lactic acid At the same time we cannot wholly de pend on this proportion, and it certain!) makes the quantity of lead somewhat to< great. The relation of the lactic acid tc lead affords one of the best methods o ed, but which probably must be acetate of recognizing it, and Berzelius alwayi mercury, principally employed it in extracting thi: ACI AGI -ic ; cl from animal fluids; it gives the clearest distinction between the lactic acid and the acetic. The lactate of iron is of a red brown co- lour, does not crystallize, and is not solu- ble in alcohol. The lactate of zinc crystal- zes. LJoth these metals are dissolved by the lactic acid, with an extrication of hydrog'en gas. The lactate of copper, ac- cording 1 to its different degrees of satura- tion, varies from blue to green and dark blue, it does not crystallize. It is only necessary to compare the de- scriptions* 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 dis- tinct from all others. Its prime equivalent mav be called 5.8. The nanceic acid of Braconnot resembles the lactic in many respects.* * ACID (LAMPIC). Sir H. Davy, during his admirable researches on the nature and properties of flame, announced the singu- lar fact, that combustible bodies might be made to combine rapidly with oxygen, at temperatures below what were necessary to their visible inflammation, Among the phenomena resulting from these new ; combinations, he remarked the production of a peculiar acid and pungent vapour from the slow combustion of ether; and from its obvious qualities he was led to suspect, that it might be a product yet new to the chemical catalogue. Mr. Fara- day, in tue 3d volume of the Journal of Science and the Arts, has given some ac- count of the properties of this new acid ; bui from the very small quantities in which he was able to collect it, was prevented j from performing any decisive experiments upon it, In the 6th volume of the same Journal, we have a pretty copious investigation of the properties and compounds of this new acid, by Mr. Daniell. From the slow i combustion of ether during six weeks, by means of a coil of platina wire sitting on the cot on wick of the lamp, (See F-.AME), he condensed with the head of an alembic, whose beak was inserted in a receiver, a pint and a half of the lampic acid liquor. When first collected it is a colourless fluid of an intensely sour taste, and pun- gent odour. Its vapour, when heated, is extremely irritating and disagreeable, and when received into the lungs produces an oppression at the chest very much resem- bling the effect of chlorine. Its specific gravity varies according to the care with which it has been prepared, from less than 1.000 to 1.008. It may be purified by careful evaporation ; and it is worthy of remark, that the vapour which rises from " it is that of alcohol, with which it is slightly contaminated, and not of ether. Thus rectified, its specific gravity is 1.015. It reddens vegetable blues, and decomposes all the earthy and alkaline carbonates, forming neutral salts with their bases, which are more or less deliquescent. Lampate of soda is a very deliquescent salt, of a not unpleasant saline tas'.e. It is decomposed by heat. It consists of 62^1 acid and 37.9 soda. Hence its prime equivalent comes out 6.47. Lampate of potash is not quite so deliquescent. Lampate of ammonia evaporates at a tem- perature below 212. It is a brown salt. Lampate of barytes crystallizes in colour- less transparent needles. Its composition is 39.5 acid and 60.5 base ; and hence the prime is 6.365, barytes being reckoned 9.75, with Dr. Wollaston. Lampate of lime is deliquescent, and has a caustic bitter taste. Lampate of magnesia has a sweet, astringent taste, like sulphate of iron. All these salts burn with flame. Lampic acid reduces gold from the muriate instantly ; and the lampates of potash and ammonia produce the same effect more slowly. A mixture of these two lampates, throws down metallic platinum from its solution. Nitrate of silver also gives a metallic preci- pitate ; but what is singular, the oxide of silver is soluble in lampic acid, but at a boilingheat falls down in the metallic state. A hot solution of nitrated protoxide of mercury exhibits a very beautiful phe- nomenon, when mixed with the acid. A shower of mercurial globules falls down through the liquid. Red oxide forms with lampic acid a bulky white salt, of sparing solubility, from which, after a few days, metallic mercury separates. Lampate of copper affords by evaporation under an exhausted receiver, blue rhomboidal crys- tals. When the solution is boiled, metal- lic copper falls. Lampate of lead is a white, sweetish, and easily crystallized salt, By analysis of' the lampate of barytes in M. M. G. Lussac and Thenard's apparatus, (See VEGETABLE ANALYSIS), Mr. Daniell infers the composition of the acid to be 40.7 carbon, -f- 7.7 hydrogen, -}- 51.6 of oxygen and hydrogen, in their aqueous ratio = 100. These numbers correspond, lie says, with what we may suppose to re- sult from I atom of carbon, 1 of hydrogen, and 1 of water, or its elements. The excess of hydrogen explains, he imagines, the property which the acid possesses of reviving the metals, whence it may be usefully applied in the arts, to plate deli- cate works with gold and platinum. The weight of its equivalent, and some of the properties of the salts, mig'ht lead tp the opinion of the lampic acid of Mr. ACI ACI Baniell being 1 merely the acetic, combined with some etherous matter. This conjec- ture must be left for future verification.* Acn> (LTTHIC). This was discovered about the year 1776 by Scheele, in analy- zing human calculi, of many of which it constitutes the greater part and of some, particularly that which resembles wood in appearance, it forms almost the whole. It is likewise present in human urine, and in that of the camel; and Dr. Pearson found it in those arthritic concretises com- monly called chalkstones, which Mr. Ten- nanthas since confirmed. It is often called uric acid. The following- are the results of Scheele's experiments on calculi, which were found to consist almost wholly of this acid : 1. Dilute sulphudc acid produced no ef- fect on the calculus, but the concentrated dissolved it; and the solution distilled to dryness left a black coal, giving- off' sulphu- rous acid fumes. 2. The muriatic acid, either dimted or concentrated, had no ef- fect on it even with ebullition. 3. Dilute nitric acid attacked it cold ; and with the assistance of heat produced an efferves- cence and red vapour, carbonic acid was evolved, and the calculus was entirely dis- solved. The solution was acid, even when saturated with the calculus, and gave a beautiful red colour to the skin in half an hour after it was applied ; when evaporat- ed, it became of a blood red, but the co- lour was destroyed by adding a drop of acid : it did not precipitate muriate of ba- rytes, or metallic solutions, even with the addition of an alkali ; alkalis rendered it more yellow, and, if superabundant, chang- ed it by a strong digesting heat to a rose colour : and this mixture imparts a similar colour to the skin, and is capable of pre- cipitating sulphate of iron black, sulphate of copper green, nitrate of silver gray, su- per-oxygenated muriate of mercury, and solutions of lead and zinc, white. Lime- water produced in the nitric solution a white precipitate, which dissolved in the nitric and muriatic acids without efferves- cence, and without destroying their acidi- ty. Oxalic acid did not precipitate it. 4. Carbonate of potash did not dissolve it, either cold or hot, but a solution of per- fectly pure potash dissolved it even cold. The solution was yellow; sweetish to the taste ; precipitated by all the acids, even the carbonic; did not render lime-water turbid ; decomposed and precipitated so- lution of iron brown, of copper gray, of silver black, of zinc, mercury, and lead, white ; and exhaled a smell of ammonia. 5. About 200 parts of lime-water dissolved the calculus by digestion, and lost its acrid taste. The solution was partly precipita- ted by acids. 6. Pure water dissolved it entirely, but it was necessary to boil for some time 360 parts with one of the cal- culus in powder. This solution reddened . tincture of litmus, did not render lime-| water turbid, and on cooling deposited in ; small crystals almost the whole of what it j had taken up. 7. Seventy -two grains dis- 1 tilled in a small glass retort over an open fire, and gradually brought to a red heat, produced water of ammonia mixed with a little animal oil, and a brown sublimate weighing 28 grains, and 12 grains of coal remained, which preserved its black co- lour on red hot iron in the open air. The brown sublimate was rendered white by a second sublimation; was destitute of smell, even when moistened by an alkali; was acid to the taste ; dissolved in boiling wa- ter, and also in alcohol, but in less quanti- ty; did not precipitate lime-water; and appeared to resemble succinic acid. Fourcroy has found, that this acid is al- most entirely soluble in 20GO times its weight of cold water, when the powder is repeatedly treated with it. From his ex- periments he infers, that it contains azote, with a considerable portion of carbon, and but little hydrogen, and little oxygen. Of its combinations with the bases we know but little. The lithate of lime is more soluble than the acid itself; but on exposure to the air it is soon decomposed, the carbonic acid in the atmosphere com- bining with the lime, and precipitating 1 both the lithic acid and new formed car- bonate of lime separate from each other. The lithate of soda appears from the ana- lysis of Mr. Tennant to constitute the chief part of the concretions formed in the joints of gouty persons. The lithate of potash is obtained by digesting calculi in caustic lixivium ; and Fourcroy recommends the precipitation of the lithic acid from this solution by acetic acid, as a good process for obtaining the acid pure in small, white, shining, and almost pulverulent needles. * Much additional information has been obtained within these few years on the na- ture and habitudes of the lithic acid. Dr. Henry wrote a medical thesis, and after- wards published a paper, on the subject, in the second volume of the new series of the Manchester Memoirs, both of which contain many important facts. He pro- cured the acid in the manner above pre- scribed by Fourcroy. 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 litmus. AVhen dissolved in nitric acid, and evapo- rated to dryness, it leaves a pink sediment. The dry acid is not acted on nor dissolved by the alkaline carbonates, or sub-carbo- nates. It decomposes soap when assisted by heat; as it does also the alkaline sul- phurets, and hydjosulphurets. No acid ACI ACI acts on it, except those that occasion its decomposition. It dissolves in hot solu- tions of potash and soda, and likewise in ammonia, but less readilv . The lithates may be formed, either by mutually satura- ting- the two constituents, or we may dis- solve the acid in an excess of base, and we may then precipitate by carbonate of am- monia. The lithates are all tasteless, and resemble in appearance lithic acid itself. They are not altered by exposure to the atmosphere. They are very sparingly so- luble 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 car- bonic. They are decomposed by the ni- trates, muriates, and acetates of barytes, strontites, lime, magnesia, and alumina. They are precipitated by all the metallic solutions except that of gold. When li- thic acid is exposed to heat, the products are carburetted hydrogen, and carbonic acid, prussic acid, carbonate of ammonia, a sublimate, consisting of ammonia com- bined 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 al- so sparingly in alcohol, It is volatile, and when sublimed a second time, becomes much whiter. The watery solution red- dens vegetable blues, but a very small quantity of ammonia destroys this proper- ty. It does not cause effervescence with alkaline carbonates. By evaporation it yields permanent crystals, but ill defined, from adhering animal matter. These red- den 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 decom- pose the earthy salts, as happens with al- kaline lithates (or urates.) Neither has it any action on the salts of copper, iron, gold, platinum, tin, or mercury. With ni- trates of silver, and mercury, and acetate of lead, it forms a white precipitate, solu- ble in an excess of nitric acid. Muriatic acid occasions no precipitate in the solu- tion of these crystals in water. These properties show, that the acid of the sub- limate is different from the uric, and from eveiy other known acid. Dr. Austin found, that by repeated distillations, lithic acid was resolved into ammonia, nitrogen, and prussic acid. See ACID (PXROLITHIC.) When lithic acid is projected into a flask with chlorine, there is formed, in a little time, muriate of ammonia, oxalate of am- monia, carbonic acid, muriatic acid, and malic acid; the same results are obtained by passing chlorine through water, hold- ing 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 prime equi- valents of carbon, and one of nitrogen. 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, de- scribes the result of an analysis of lilhic acid, effected also by ignited oxide of cop- per, 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, nitrogen 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 40.000 1 = 1.750 100.000 4.375 M. Berard has published an analysis of lithic acid since Dr. Prout, in which he al- so employed oxide of copper. The following are the results : Carbon 33.61 r"2 Carbon Oxygen 18.89 which ap-J 1 Oxygen Hydrogen 8.34 proach to j 4 Hydrogen Nitrogen 39.16 \_1 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 accom- modate an arrangement of prime equiva- lents to these discrepancies. The lowest number would require, on the Daltonian plan, an association of more than twenty atoms, the grouping of which is rather a spoil 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* ACI ACI * ACID (MALIC. ) The acid of apples ; the same wilh that which is extracted from the fruit of the mountain ash. See ACID (SORBIC.*) * ACID (MARGARIC.) When we immerse soap made of pork-grease and potash, in a large quantity of water, one part is dissolv- ed, while another part is precipitated, in the form of several brilliant pellets. These are separated, dried, washed in a large quantity of water, and then dried on a fil- ter. They are now dissolved in "boiling alcohol, sp. gr. 0.820, from which, as it cools, the pearly substance falls down pure. On acting on this with dilute muriatic acid, a substance of a peculiar kind, which M. Chevreul, the discoverer, calls margarine, or margaric acid, is separated. It must be Well washed with water dissolved in boil- ing 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 simi- lar to that of melted wax. Its specific gra^ vity is inferior to water. It melts at 134 F. into a very limpid, colourless liquid, which crystallizes 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 ac- tion on the colour of litmus ; but when heated so as to soften without melting, the blue was reddened. It combines with the salifiable bases, and forms neutral com- pounds. 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 supcr- margarates, the former being converted into the latter, by pouring a large quanti- ty of water on them. Other fats besides that of the hog yield this substance. Jlcid. Jlase. Margarate of potash consists of 100 17 77 Supermargarate - - - - 100 8.88 Margarate of soda - - - - 100* 12.72 Barytes 100 28.93 Strontites 100 20.23 Lime 100 11.06 Potash Supermargarate of Human fat 100 8.85 Sheep fat 100 8.68 Ox fat 100 8.78 Jaguar fat 100 8.60 Goose fat 100 8.77 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. 1st, In very fine long nee- dles, disposed in fiat stars, *2d, In very fine and rery short needles, fyrming waved figures, like those of the margaric acid of carcasses. 3d, In very large brilliant crys- tals disposed in stars, similar to the garic acid of the hog. The margaric acids of man and the hog resemble eacti other ; as do those of the ox and the sheep ; and of the goose and the jaguar. The com- pounds with the bases, are real soaps. The solution of alcohol affords the transparent soap of this country. Annales de Chimie, several volumes.* * ACID (MKCOJHC). This acid is a consti- tuent of opium. It was discovered by M. Sertuerner, who procured it in the follow- ing way : After precipitating the morphia, from a solution of opium, by ammonia, he added to the residual fluid a solution of the muriate of harytes. A precipitate is in this way formed, which is supposed to be a quadruple compound, of barytes, mor- phia, extract, and the meconic acid. The extract is removed by alcohol, and the barytes by sulphuric acid ; when the me- conic acid is left, merely in combination with a portion of the morphia ; and from this it is purified by successive solutions and evaporations. The acid, when sub- limed, 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 crystallizable salt with lime, which is not decomposed by sulphuric acid ; and what is curious, it seems to pos sess no particular power over the human body, when received into the stomach. The essential salt of opium, obtained in M. Derosne's original experiments, was probably the meconiate of morphia. Mr. Robiquet has made a useful modifi- cation of the process for extracting mecon- ic acid. He treats the opium witli magne- sia, to separate the morphia, while me- coniate of magnesia is also formed. The magnesia is removed by adding muriate of barytes, and the barytes is afterwards se- parated by dilute sulphuric acid. A lar- ger proportion of meconic acid is thus ob- tained. Mr. Robiquet denies that meconic acid precipitates iron from the muriate ; but, according' to M. Vogel, its power of red- dening solutions of iron is so gTeat, as to render it a more delicate test of this metal, than even the prussiate of potash. To obtain pure meconic acid from the meconiate of barytes, M. Choulant tritu- rated it in a mortar, with its own weight of glassy boracic 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 meconic acid sublimed, in the state of fine white scales or plates. It has a strong sour taste, which leaves be- hind it an impression of bitterness. It dis- solves readily in water, alcohol, and ether. It reddens the greater number of vegeta- ACI \ ble blues, and changes the solutions of f- iron to a cherry-red colour. When these solutions are heated, the iron is precipi- ' tated in the state of protoxide. The meconiates examined by Choulant, are the following: 1st, VIecouiate of potash. Tt crystallizes in four sided tables, is soluble in twice its weight of wafer, and is composed of Meconic acid 27 2.7 Potash 60 6.0 Water 13 100 It is destroyed by heat. 2d, Meconiate of soda. It crystallizes in soft prisms, is soluble in five times its weight of water, and seems to effloresce. It is destroyed by heat. It consists of Acid ' 32 3.2 Soda 40 4.0 Water 28 100 3d Meconiate of ammonia. It crystal- Mzes in star-form needles, which, when sublimed, lose their water of crystalliza- tion, and assume the shape of scales. The crystals are soluble in 1 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 tritura- ted with 3 parts of meconiate of barytes, and heat be applied to the mixture, me- coniate of ammonia sublimes, and muriate of barytes remains. 4th, Meconiate of lime. It crystallizes in prisms, and is soluble in eight times its i weight of water. It consists of Acid 34 2 882 Lime 42 3.560 Water 24 100 As the potash and lime compounds give nearly the same acid ratio, we may take their mean of it, as the true prime = 2.8.* * ACTD (MKI.ASSIC). The acid present in melasses, which has been thought a pe- culiar acid by some, by others, the acetic.* ACID (MELLITIC). M. Klaproth disco- vered in the mellite, or honey-stone, what he conceives to be a peculiar acid of the vegetable kind, combined with alu- mina. This acid is easily obtained by re- ducing the stone to powder, and boiling it in about 70 times its weight of water; when the acid will dissolve, and may be separated from the alumina by filtration. By evaporating the solution, it may be ob- tained in the form of crystals. The fol- lowing are its characters : ACI It crystallizes in fine needles or globules by the union of these, or small prisms. Its taste is at first a sweetish sour, which leaves a bitterness behind. On a plate of hot metal it is readily decomposed, and dissipated in copious gray fumes, which affect not the smell; leaving behind a small quantity of ashes, that do not change either red or blue tincture of litmus. Neu- tralized by potash it cr-, stalli/es in groups of long prisms : by soda, in cubes, or tri- angular laminx, sometimes in groups, sometimes single ; and by ammonia, in beautiful prisms with six planes, which soon lose their transparency, and acquire a silvery white hue. If tl>e mellitic acid be dissolved in lime-water, and a solution of calcined strontian or barytes be drop- ped into it, a white precipitate is thrown down, which is redissolved on adding mu- riatic acid. With a solution of acetate of barytes, it produces likewise a white pre- cipitate, which nitric acid redissolves. With solution of muriate of barytes, it pro- duces no precipitate, or even cloud ; but after standing- some time, fine transparent needly crvstals are deposited. The mel- litic acid produces no change in a solution of nitrate of silver. From a solution of nitrate of mercury, either hot or cold, it throws down a copious white precipitate, which an addition of nitric acid imme- diately redissolves. With nitrate of iron it gives an abundant precipitate of a dun yellow colour, which may be redissolved by muriatic acid. With a solution of ace- tate of lead, it produces an abundant pre- cipitate, immediately redissolved on add- ing nitric acid. With acetate of copper, it produces a grayish-green precipitate; but it does not affect a solution of muriate of copper. Lime-water precipitated by it, is immediately redissolved on adding 1 nitric acid. M. Klaproth was never able to convert this acid into the oxalic by means of nitric acid, which only changed its brownish co- lour to a pale yellow. * The mellite, or native mellate of alu- mina, consists, according to Klaproth, of 46 acid -\- 16 alumina -f- 38 water == 100; from which, calling- the prime of alumina 3.2, that of mellitic acid appears to be 9.2.* * ACID (MEXISPKRMTC). The seeds of menispermum cocci/his being macerated for 24 hours in 5 times their weight of water, first cold, and then boiling hot, yield an infusion, from which solution of subacetate of lead throws down a menispermate of lead. This is to be washed and drained, diffused through water, and decomposed by a current of sulphuretted hydrogen gas. The liquid thus freed from lead, is to be deprived of sulphuretted hydrogen by heat, and tfeen forms solution of minis- ACI ACI permic acid. By repeated evaporations and solutions in alcohol, it loses its bitter taste, and becomes a purer acid. It occa- sions no precipitate with lime-water ; with nitrate of barytes it yields a gray precipi- tate ; with nitrate of silver, a deep yellow; and with sulphate of magnesia, a copious precipitate.* * Ar< r ( vio^YBDic). The native sulphu- ret of molybdenum being 1 roasted for some time, and dissolved in water of ammonia, when nitric acid is added to this solution, the molybdic acid precipitates "in fine white scales, which become yellow, on melting and subliming them. It changes the vegetable blues to red, but less readi- ty and powerfully than the following acid. M. Bucholz found that 100 parts of the sulphuret gave 90 parts of molybdic acid, tn other experiments in which he oxidized molybdenum, he found that 100 of the metal combined with from 49 to 50 of oxy- gen. Berzelius, after some vain attempts to analyze the molybdates of lead and ba- rytes, found that the only method of ob- taining an exact result was to form a mo- lybdate of lead. He dissolved 10 parts of neutral nitrate of lead in water, and pour- ed an excess of solution of crystallized molybdate of ammonia into the liquid. The molybdate of lead, washed, dried and heated to redness, weighed 11.068. No traces of lead were found in the liquid by sulphate of ammonia; hence these 11.068 of lead, evince 67.3 per cent of oxide of tead. This salt then is composed of Molybdic acid 39.194 9.0 Oxide of lead 60.806 14.0 100.000 And from Bucholz we infer, that this prime equivalent 9, consists of 3 of oxy- gen _j. 6 metal; while molybdotis acid will be 2 oxygen -f 6 metal = 8.0. Molybdic acid has a specific gravity of 3.460. In an open vssel it sublimes into brilliant yellow scales ; 960 parts of boiling water dissolve one of it, affording a pale yellow solution, which reddens litmus, but has no taste. Sulphur, charcoal, and several metals decompose the molybdic acid. Molybdate of potash is a colourless salt. Molybdic acid gives, with nitrate of lead, a white precipitate, soluble in nitric acid ; with the nitrates of mercury and silver, a white flaky precipitate ; with ni- trate of copper, a greenish precipitate; with solutions of the neutral sulphate of zinc, muriate of bismuth, muriate of anti- mony, nitrate of nickel, muriates of gold and platinum, it produces white precipi- tates. When melted with borax, it yields a bluish colour ; and paper dipped in its solution becomes, in the sun, of a beauti- ful blue.* The neutral alkaline molybdates preci- pitate all metallic solutions. Gold, roti- riate of mercury, zinc, and manganese, are precipitated in the form of a white powder; iron and tin, from their solutions in muriatic acid, of a brown colour ; cobalt, of a rose colour ; copper, blue ; and the solutions of alum and quicklime, white. If a dilute solution of recent muriate of tin be precipitated by a dilute solution of molybdate of potash, a beautiful blue powder is obtained. The concentrated sulphuric acid dis- solves a considerable quantity of the mo- lybdic acid, the solution becoming of a fine blue colour as it cools, at the same time that it thickens ; the colour disap- pears again on the application of heat, but returns again by cooling. A strong heat expels the sulphuric acid. The nitric acid has no effect on it ; but the muriatic dissolves it in considerable quantity, and leaves a dark blue residuum when dis- tilled. With a strong heat it expels a por- tion of sulphuric acid from sulphate of potash. It also disengages the acid from nitre and common salt by distillation. It has some action upon the filings of the me- tals in the moist way. The molybdic acid has not yet been em- ployed in the arts. * ACID (MOLYBDOUS). The deutoxide of molybdenum is of a blue colour, and possesses acid properties. Triturate 2 parts of molybdic acid, with 1 part of the metal, along with a little hot water, in a porcelain mortar, till the mixture assumes a blue colour. Digest in 10 parts of boil- ing water, filter, and evaporate the liquid in a heat of 120. The blue oxide sepa- rates. It reddens vegetable blues, and forms salts with the bases. Air or water, when left for some time to act on molyb- denum, convert it into this acid. It con- sists of about 100 metal to 34 oxygen,* ACIP (MonoxYLtc). In the botanic gar- den at Palermo, Mr. Thompson found an uncommon saline substance on the trunk of a white mulberry tree. It appeared as a coating on the surface of the bark in lit- tle granulous drops of a yellowish and blackish brown colour, and had likewise penetrated its substance. M. Klaproth, who analyzed it, found that its taste was somewhat like that of succinic acid ; on burning coals it swelled up a little, emit- ted a pungent vapour scarcely visible to the eye, and left a slight earthy residuum. Six hundred grains of the bark loaded with it were lixiviated with water, and afforded 320 grains of a light salt, resem- bling in colour a light wood, and compos- ed of short needles united in radii. It was not deliquescent ; and though the crystals did not form till the solution was greatly condensed by evaporation, it is not very ACI ACI soluble, since 1000 parts of water dissolve but 35 with heat, and 15 cold. This salt was found to be a compound of lime and a peculiar vegetable acid, with some extractive matter. To obtain the acid separate, M. Klap- roth decomposed the calcareous salt by acetate of lead, and separated the lead by sulphuric acid. He likewise decomposed I it directly by sulphuric acid. The pro- l duct was still more like succinic acid in I taste ; was not deliquescent ; easily dis- solved both in water and alcohol ; and did i not precipitate the metallic solutions, as it did in combination with lime. Twenty grains being- slightly heated in a small > glass retort, a number of drops of an acid liquor first came over ; next a concrete salt arose, that adhered flat against the top and part of the neck of the retort in the form of prismatic crystals, colourless and transparent ; and a coaly residuum re- mained. The acid was then washed out, and crystallized by spontaneous evapora- tion. Thus sublimation appears to be the best mode of purifying the salt, but it ad- hered too strongly to the lime to be sepa- rated from it directly by heat without be- ing decomposed. Not having a sufficient quantity to de- termine its specific characters, though he conceives it to be a peculiar acid, coming nearest to the succinic both in taste and ether qualities, Mr. Klaproth has pro- visionally given it the name of moroxylic, and the calcareous salt containing it that of moroxylate of lime. ACID (Mucic). This acid has been gene rally known by the name of saccholactic, because it was first obtained from sugar of inilk ; but as all the gums appear to afford it, and the principal acid in sugar of milk ;is the oxalic, chemists in general now dis- tinguish it by the name of mucic acid. It was discovered by Scheele. Having poured twelve ounces of diluted nitric acid on four ounces of powdered sugar of milk in a glass retort on a sand bath, the mixture became gradually hot, and at length effervesced violently, and contin- ued to do so for a considerable time after the retort was taken from the fire. It is necessary therefore to use a large retort, and not to lute the receiver too tight. The effervescence having nearly subsided, the retort was again placed on the sand heat, and the nitric acid distilled off, till the mass had acquired a yellowish colour. This exhibiting no crystals, eight ounces more of the same acid were added, and the distillation repeated, till the yellow colour of the fluid disappeared. As the fluid was inspissated by cooling, it was redissolved in eight ounces of water, and filtei-ed. The filtered liquor held oxalic acid in solution, and seven drams and a Von. i [8] half of a white powder remained on the filter. This powder was the acid under consideration. If one part of gum be heated gently with two of nitric acid, till a small quantity of nitrous gas and of carbonic acid is disen- gaged, the dissolved mass will deposite on cooling the mucic acid. According to Fourcroy and Vauquelin, different gums yield from 14 to 26 hundredths of this acid. This pulverulent acid is soluble in about 60 parts of hot water, and by cooling, a fourth part separates in small shining scales, that grow white in the air. It de- composes the muriate of barytes, and both the nitrate and muriate of lime. It acts very little on the metals, but forms with their oxides salts scarcely soluble. It pre- cipitates the nitrates of silver, lead, and mercury. With potash it forms a salt solu- ble in eight parts of boiling water, and crystallizable by cooling. That of soda re- quires but five parts of water, and is equal- ly crystallizable. Both these salts are still more soluble when the acid is in excess. That of ammonia is deprived of its base by heat. The salts of barytes, lime, and mag- nesia, are nearly insoluble. * Mucic or saccholactic acid has been analyzed recently with much care ; Hydrogen. Carbon. Oxygen. Gay-Lussac, 3.62 -f- 33.69 -f 62.69 =100 Berzelius, 5.105 -f 33.430 -f 61.465=100 From saclactate of lead, Berzelius has inferred the prime equivalent of the acid to be 13.1.* * ACID (MURIATIC). Let 6 parts of pure and well dried sea salt be put into a glass retort, to the beak of which is luted, in a horizontal direction, a long glass tube arti- ficially refrigerated, and containing a quan- tity of ignited muriate of lime. Upon the salt pour at intervals 5 parts of concentrat- ed oil of vitriol, through a syphon funnel, fixed, air-tight, in the tubulure of the re- tort. The free end of the long tube being recurved, so as to dip into the mercury of a pneumatic trough, a gas will issue, which on coming in contact with the air, will form a visible cloud, or haze, presenting, when viewed in a vivid light, prismatic colours. This gas is muriatic acid. When received in glass jars over dry mercury, it is invisi- ble, and possesses all the mechanical pro- perties of air. Its odour is pungent and peculiar. Its taste acid and corrosive. Its specific gravity, according to Sir H. Davy, is such, that 100 cubic inches weigh 39 grains, while by estimation, he says, they ought to be 38.4 gr. By the latter num- ber the specific gravity, compared to air, becomes 1.2590. By the former number the density comes out 1.2800. M. Gay- Lussac states the sp. gr. at 1.2780. Sir H.'s second number makes the prime equiva- AC1 AC1 lent of chlorine 4.43, which comes near to Berzelius's latest result; while his first number makes it 4.48, (See Cnr.oniNK). As the attraction of muriatic acid gas for hygrometric water is very strong, it is very probable that 38.4 grs. may be the more exact weight of 100 cubic inches, regard- ing *he same bulk of air as = 30.5. If an inflamed taper be immersed in it, it is in- stantly extinguished. It is destructive of animal life ; but the irritation produced by it on the epiglottis scarcely permits^its de- scent into the lungs. It is merely changed in bulk by alterations of temperature ; it experiences no change of state. When potassium, tin, or zinc, is heated in con- tact with this gas over mercury, one-half of the volume disappears, and the remain- der is pure hydrogen. On examining the solid residue,* it is found to be a metallic chloride. Hence muriatic acid gas con- sists of chlorine and hydrogen, united in equal volumes. This view of its nature was originally given by Scheele, though obscured by terms derived from the vague and visionary hypothesis of phlogiston. The French school afterwards introduced the belief that muriatic acid gas was a compound of an unknown radical and water ; and that chlorine consisted of this radical and oxygen. Sir H. Davy has the distinguished glory of refuting the French hypothesis, and of proving by decisive ex- periments, that in the present state of our knowledge, chlorine must be regarded as a simple substance ; and muriatic acid gas as a compound of it with hydrogen. This gaseous acid unites rapidly, and in large quantity, with water. The following table of its aqueous combinations, was con- structed after experiments made by Mr. E. Davy, in the laboratory of the Royal In- stitution, under the inspection of Sir H. Davy. At temperature 45, barometer 30. 100 parts of solution of muriatic gas, in Of muriatic acid water, of sp. gravity gas, parts. 1 -21 contain 42.43 1.20 40.80 1.19 38.38 1.17 34.34 1.16 32.32 1.15 30.30 l.U 28.28 1.13 26.26 1 12 24.24 1.11 22.30 1.10 20.20 1.09 18.18 1.08 16.16 1.07 14.14 106 12.12 1 05 10.10 1.04 8.08 1.03 6.06 100 parts of solution of muriatic gas, in Of muriatic acid water, of sp. gravity gas, parts. 1.02 contain 4.04 1.01 2.02 At the temperature of 40 Fahrenheit, ; water absorbs about 480 times its bulk of gas, and forms solution of muriatic acid | gas in water, the specific gravity of which is 1.2109. Sir H. Davy's Elements. In the Annals of Philosophy for Octo- i ber and November 1817, there are two papers on the constitution of liquid muri- atic acid with tables, by Dr. Ure, which coincide nearly with the preceding results. They were founded on a great number of experiments carefully performed, which are detailed in the October number. In \ mixing strong liquid acid with water, he found that some heat is evolved, and a small condensation of volume is experien- ced, contrary to the observ?tion of Mr. Kirvvan. Hence this acid forms no longer an exception, as that eminent chemist taught, to the general law of condensa- tion of volume, which liquid acids obey in their progressive dilutions. Hitherto in- deed many chemists have, without due consideration, assumed the half-sum or arithmetical mean of two specific gravities, to be the truly computed mean ; and on comparing the number thus obtained with that derived from experiment, they have inferred the change of volume, occasion- ed by chemical combination. The errors into which this false mode of computation leads are excessively great, when the two bodies differ considerably in their specific gravities. A view of these erroneous re- sults was given in Dr. Ure's third table of sulphuric acid, published in the 7th num- ber of the Journal of Sciences and the Arts, and reprinted in this Dictionary, ar- ticle SPECIFIC GRAVITY. "When, however, the two specific gravities do not differ much, the errors become less remarkable. It is a singular fact, that the arithmetical mean, which is always greater than the rightly computed mean specific gravity, gives in the case of liquid muriatic acid, an error in excess, very nearly equal to the actual increase of density. The curious coincidence thus accidentally produced, between accurate experiments and a false mode of calculation is very instructive, and ought to lead chemists to verify every anomalous phenomenon, by independent modes of research. Had Mr. Kirwan, for example, put into a nicely graduated tube 50 measures of strong muriatic acid, and poured gently over it 50 measures of water, he would have found after agita- tion, and cooling the mixture to its former temperature, that there was a decided diminution of volume, as Dr. Ure experi- mentally ascertained.* ACI ACI TABLE of real Muriatic Aeid, 8tc. in 100 of the Liquid Acid, by Dr. UHE, Sp.Gr. Dry Add. Acid Gas. Chlo- rine. Sp.Gr. Dry Acid. Acid Chlo- Gas. rine. Sp.Gr. Dry Acid. Ada Gas. Chlo- rine. 1.1920 28.3 37.60 36.50 1.1272 18.68 24.82', 24.09 \ 1.0610 9.05 1203 11.68 1.1900 28.02 37.22 36.13 1.1253 18.39 24.4423.72 .0590 8.77 11.65 11.31 1.1881 27.73 36.85 35.77 1.1233 18.11 24.06! 23.36 .0571 8.49 11.28 10.95 1.1863 27.45 36.47 35.40 1.1214 17.83 23.69 22.99 .0552 8.21 1J.90 10.58 1.1845 27.17 36.10 35.04 1.1194 17.55 23.31)22.63 .05)3 7.92 10.53 10.22 1.1827 26.88 35.72 34.67 1.117.; 17.26 22.93 22.26 .0514 7.64 10.15 9.85 1.1808 26.60 35.34 34.31 1.1155 16.98 22.56 21.90 .0495 7.36 9.77 9.49 1.1790 26.32 34.97 33.94 1.1134 16.70 22.18 21.53 .0477 7.07 9.40 9.12 1.1772 26.04 34.59 33.58 1.1115 16.41 21.81 21.17 .0457 6.79 9.02 8.76 1.1753 25.75 34.22 33.21 1.1097 16.13 21.43 20.80 .0438 6.51 8.65 8.39 1.1735 25.47 53.84 32.85 1.1077 15.85 21.05 20.44 .0418 6.23 8.27 8.03 1.1715 25.19 33.46 32.48 1.1058 15.56 20.68 19.07 1.0399 5.94 7.89 7.66 1.1698 24.90 33.09 32.12 1.1037 15.28 20.30 19.71 1.0380 5.66 7.52 7.30 1.1679 24.62 32.71 31.75 1.1018 1500 19.93 19.34 1.0361 5.38 7.14 6.93 1.1661 24.34 33.34 31.39 1.0999 14.72 19.55 18.9^ 1.0342 5.09 6.77 6.57 1.1642 24.05 31.96 31.02 1.0980 14.43 19.17 18.61 1.0324 4.81 6.39 6.20 1.1624 23.77 31.58 30.66 1.0960 14.15 18.80 18.25 1.0304 4.53 6.02 5.84 1.1605 23.49 31.21 30.29 1.0941 13.87 18.42 17.88 1.0285 4.24 5.64 5.47 1.1587 23.20 30.83 29.93 1.0922 13.58 18.04 17.52 1.0266 3.96 5.26 5.11 1.1568 22.92 30.46 29.56 1.0902 13.30 i 17.67 17.15 1.0247 3.68 4.89 4.74 1.1550 22.64 30.08 29.20 1.0883 13.02il7.29 16.79 1.0228 3.39 4.51 4.38 1.1531 22.36 29.7U 28.83 1.0863 12.73ll6.92 16.42 1.0209 3.11 4.14 4.01 1.1510 22.07 2933 28.47 1.0844 12.45|16.54 16.06 1.0190 2.83 3.76 3.65 1.1491 21.79 29.95 28.10 1.0823 12.17 16.17 15.69 1.0171 2.55 3.38 3.28 1.1471 21.51 28.57 27.74 1.0805 11.88 15.79 15.33 1.0152 2.26 3.01 2.92 1.1452 21.22 28.20 27.37 1.0785 11.60 15.42 14.96 1.0133 1.98 2.63 2.55 1.1431 20.94 27.82 27.01 1.0765 11.32 15.04 14.60 1.0114 1.70 2.26 2.19 1.1410 20.66 27.45 26.64 1.0746 11.04 14.66 14.23 1.0095 1.41 1.88 1.82 1.1391 20.37 27.07 26.28 1.0727 10.75 14.29 13.87 1.0076 1.13 1.50 1.46 1.1371 20.09 26.69 25.91 1.0707 10.47 13.91 13.50 1.0056 0.85 1.13 109 1.135119.81 26.32 25.55 1.0688 10.19 13.54 13.14 1.0037 0.56 0.752 0.73 1.133219,53 29.94 25.18 1.0669 9.90 1.3.16 12.77 1.0019 0.28 0.376 0.365 1.131219.24 25.57 24.82 1.0649 9.62 12.78 12.41 1.000 0.00 0.000 0.000 1.1293(18.96 25.19 24.45 1.0629 9.34 12.41 12.04 The fundamental density of the acid of :he preceding table is 1.1920, which is as strong 1 as it is comfortable to make or to use in chemical researches. To find the quantity of real acid in that possessed of greater density, we have only to dilute it !with a known proportion of water, till it come within the range of the table. The short memoir in the Annals for November, contains the logarithmic series correspon- ding to the range of densities and acid strengths; but for all ordinary purposes the following simple rule will serve : Multiply the decimal part of the number denoting the specific gravity by 147, the product will be very nearly the per-cen- tage of dry acid, or by 197 when we wish to know the per-centage of the acid S as - EXAMPLES. 1. The specific gravity is 1.141 ; required the proportion of dry acid in 100 parts. 0.141 X 147 =* 20.72, Bv the table it s 20.66. 2. The specific gravity is 1.096; the quantity of acid gas is sought. 0.096 X 197 = 18.9. By the table it is 18.8. According to the new doctrine of Sir H. Davy there is no such substance as the dry acid ; and therefore in a theoretical point of view, the column containing it might have been expunged. But for practical purposes it is very useful, for it shows directly the increase of weight which any alkaline or earthy base will acquire, by combining with the liquid acid. Thus, if we unite 100 grs. of liquid acid sp. gravity 1.1134 with quicklime, we see that the base will, on evaporation to dryness, be heavier by 16.7 grains. We would require a little calculation to determine this amount from the other columns. We have seen it stated that water, in absorb- ing 480 times its bulk of the acid gas, be- comes of specific gravity 1.2109. If we compute from these data the increase of its bulk, we shall find it equal to 1.42, or AC1 ACI nearly one and a half the volume of the water. 481 parts occupy only 1.42 in bulk, a condensation of about 340 into one. The consequence of this approximation of the particles, is the evolution of their latent heat ; and accordingly the heat produced in the condensation of the gas is so great that it melts ice almost as rapidly as the steam of boiling water does. Hence also in passing the gas from the beak of a retort into a Woulfe's apparatus containing water to be impregnated, it is necessary to sur- round the bottles with cold water or ice, if we wish a considerable condensation. Dr. Thomson, in the second volume of his System of Chemistry, 5th edition, has committed some curious mistakes in treat- ing of the aqueous combination of muriatic acid gas. He says, " A cubic inch of water at the temperature of 60, barome- ter 29.4, absorbs 515 cubic inches of muri- atic acid gas, which is equivalent to 308 grains nearly. Hence water thus impreg- nated contains 0.548, or more than half of its weight of muriatic acid, in the same state of purity, as when gaseous. I caused a current of gas to pass through water, till it refused to absorb any more. The specific gravity of the acid thus obtained was 1.203. If we suppose that the water in this experiment absorbed as much gas as in the last, it will follow from it that 6 parts of water, being saturated with this gas, expanded so as to occupy very nearly the bulk of 11 parts; but in all my trials the expansion was only to 9 parts. This would indicate a specific gravity of 1.477; yet upon actually trying water thus saturated, its specific gravity was only 1.203. Is this difference owing to the gas that escapes during the taking of the specific gravity ?" page 232. \Ve are here presented with a puzzle for the chemical student ; and an instruc- tive example, when one takes the trouble of unravelling the hank, of a contest be- tween experimental results and false computation. Granting all the experimen- tal statements to be exact, none of the consequences follow. For, in the first place, 515 cubic inches of muriatic acid gas do not weigh 308 grains nearly, but only 201 grains ; and hence, secondly, his liquid acid could contain at utmost only 0.443 of its weight of gas, instead of 0.548 ; and, in the third place, the calculated en- largement of bulk is 1.5, or from 6 to 9, and not to 11 ; so that the quere with which he concludes is superseded. But another quere may here be started, about the experimental results themselves. Dr. Thomson says, that a cubic inch of water absorbs 515 cubic inches of gas, and ac- quires the specific gravity by experiment of 1.203. Sir II. Davy states, that a cubic inch of water absorbs about 480 cubic inches of gas, and forms a liquid of specific gravity 1.2109. Now it is remarkable that Dr. Thomson's additional condensation of 35 inches of gas gives a less specific gravity than we have in the stronger acid of Sir H. Davy. But farther, the table constructed by Sir H. and E. Davy presents for its funda- mental density the number 1.20 of Dr. Thomson. Now this particular acid of 1.20 was carefully analyzed by nitrate of silver, and is stated by Sir H. to contain in 100 grains 40.8 grains of condensed gas. Of course we have a remainder of 59.2 grains of water. 40.8 gr. of g'as have a vol- ume at the ordinary pressure and temper- ature of 104 cubic inches, reckoning the weight of 100 cubic inches to be 39.162 gr. with Dr. Thomson- And as 59.2 gr. of water have absorbed 104 cubic inches, we have the following proportion, 59.2: 104 : : 252.5 : 443. Thus a cubic inch has con- densed only 443 cubic inches, instead of 515. as by Dr. Thomson. And whatever error may be supposed to be in their table, it is but minute, and undoubtedly does not consist in underrating the quan- tity of condensed gas. By uniting the base of this gas with silver, and also with potassium, Berzelius has lately determined the prime equivalent of muriatic acid to be 3.4261, whence chlorine comes out 4.4261, and muriatic gas 4.4261 -f- 0.125 (the prime of hydro- gen) = 4.5511. But if we take 1.278 as the specific gravity of this acid gas, then the specific gravity of chlorine will be twice that number, minus the specific gravity of hydrogen, or (1.278 X 2) 0.0694 = 2.4866 ; and as chlorine and hydrogen unite volume to volume, then the relation of the prime of chlorine will 2.4866 be to that of hydrogen == = 35.83. 0.0694 If we divide this by 8, we shall have 4.48, to represent the prime equivalent of chlo- rine, and 4.48-4-0.125 = 4.605 for that of muriatic acid gas. But if we call the specific gravity of dry muriatic acid gas 1.2590, as Sir H. Davy says it should be by calculation, then the sp. gravity of chlorine becomes 2.4486, and its prime 4.42, a number agreeing nearly with the latest researches of Berzelius. Muriatic acid, from its composition, has been termed by M. Gay-Lussac the hydro- chloric acid ; a name objected to, on good grounds, by Sir II. Davy. It was prepar- ed by the older chemists in a very rude manner, and was called by them spirit of salt.* In the ancient method, common salt was previously decrepitated, then ground with dried clay, and kneaded or wrought ACI ACI with water to a moderately stiff consis- tence, after which it was divided into balls of the size of a pigeon's egg: these balls, being previously well dried, were put into a retort, so as to fill the vessel two-thirds full ; distillation being then proceeded upon, the muriatic acid came over when the heat was raised to ignition. In this process eight or ten parts of clay to one of salt are to be used. The retort must be of stone-ware well coated, and the furnace must be of that kind called reverberatory. It was formerly thought, that the salt was merely divided in this operation by the clay, and on this account more readily gave out its acid; but there can be little doubt, that the effect is produced by the siliceous earth, which abounds in large proportions in all natural clays, and de- tains the alkali of the salt by combining with it. * Sir H. Davy first gave the just ex- planation of this decomposition. Common salt is a compound of sodium and chlorine. The sodium may be conceived to combine with the oxygen of the water in the earth, and with the earth itself, to form a vitreous compound ; and the chlorine to unite with the hydrogen of the water, forming muriatic acid gas. " It is also easy," adds lie, " according to these new ideas, to ex- plain the decomposition of salt by moisten- ed litharge, the theory of which has so much perplexed the most acute chemists. It may be conceived to be an instance of compound affinity ; the chlorine is attrac- ted by the lead, and the sodium combines with the oxygen of the litharge, and with water, to form hydrate of soda, which gradually attracts carbonic acid from the air. When common salt is decomposed by oil of vitriol, it was usual to explain the phenomenon by saying, that the acid by its superior affinity, aided by heat, expelled the gas, and united to the soda. But as neither muriatic acid nor soda exists in common salt, we must now modify the explanation, by saying that the water of the oil of vitriol is first decomposed, its oxygen unites to the sodium to form soda, which is seized on by the sulphuric acid, while the chlorine combines with the hy- drogen of the water, and exhales in the form of muriatic acid gas." As 100 parts of dry sea salt, are capable of yielding 62 parts by weight of muriatic acid gas, these ought to afford by econo- mical management nearly 221 parts of liquid acid, specific gravity 1.142, as pre- scribed by the London College, or 200 parts of acid sp. gr. 1.160, as directed by the Edinburgh and Dublin Pharmacopeias. The fluid ounce of the London College feeing .jig of a wine pint, is equal in weight fo 1.265817 Ibs. Troy, divided by 16, which gives 453.7 grains Troy. This weight multiplied by 1.142 = the specific gravity of their standard acid, gives the product 520.4 ; which being multiplied by 0.2763, the muriatic gas in 1.00 by Dr. Ure's table, we have 143.8 or 144 for the acid gas in the liquid ounce, of the above density. We find this quantity equivalent to 200 gr. of carbonate of lime. Had the fundamental number 28.3 of Dr. Ure's table been made 28.6, as one of his ex- periments related in the Annals of Philoso- phy indicates, then a liquid ounce of the above acid would have dissolved upwards of 202 grains of pure calcareous carbonate. But when the results fluctuate between 28.3 and 28.6, they become exceedingly difficult to decide upon. As the difference is altogether unimportant in practice, he does not feel himself justified in making any alteration in his table. The limit of its error is certainly a fraction of one per cent. Were 29.0 the leading number, then a liquid oz. of acid of 1.142, would dissolve 205 grains of calc spar. It is obvious that the series of specific gravities given in the above table, is altogether independent of this question. If 28.6 should be prefer- red by any person, let him multiply this number by 0.9, 0.8, 0.7, 0.6, &c. and he will have a series of numbers represen- ting the quantities of dry acids correspon- ding to the specific gravities 1.190, 1.1735, 1.1550, 1.1351, &c. for these densities are opposite to 90, 80, 70, 60, &c. per cent of the strong acid. When this acid is con- taminated with sulphuric acid, it affords precipitates with muriates of barytes and strontites.* We have described the ancient method of extracting the gas from salt, which is now laid aside. The English manufacturers use iron stills for this distillation, with earthen heads: the philosophical chemist, in making the acid of commerce, will doubtless prefer glass. Five parts, by weight, of strong sulphuric acid are to be added to six of decrepitated sea salt, in a retort, the upper part of which is furnished with a tube or neck, through which the acid is to be poured upon the salt. The aperture of this tube must be closed with a ground stopper immediately after the pouring. The sulphuric acid im- mediately combines with the alkali, and expels the muriatic acid in the form of a peculiar air, which is rapidly absorbed by water. As this combination and disen- gagement take place without the applica- tion of heat, and the aerial fluid escapes very rapidly, it is necessary to arrange and lute the vessels together before the sul- phuric acid is added, and not to make any fire in the furnace until the disengagement begins to slacken ; at which time it must be very gradually raised. Be/ore the mo- ACI ACI dcrn improvements in chemistry were made, a great part of the acid escaped for want of water to combine with ; but by the use of Woulfe's apparatus, (See LABORA- TORY,) the acid air is made to pass through water, in which it is nearly condensed, and forms muriatic acid of double the weight of the water, though the bulk of this fluid is increased one-half only. The acid con- densed in the first receiver, which con- tains no water, is of a yellow colour, aris- ing from the impurities of the salt. The marine acid in commerce has a straw colour: but this is owing to accidental im- purity ; for it does not obtain in the acid produced by the impregnation of water with the pure aeriform acid. The muriatic acid is one of those longest known, and some of its compounds are among those salts with which we are most familiar. * The muriates, when in a state of dry- ness, are actually chlorides, consisting of chlorine and the metal ; but since moisture makes them instantly pass to the state of muriates, we shall describe them under this article. The sulphates and nitrates, when destitute of water, may in like man- ner be regarded as containing neither acid nor alkali, and might therefore be trans- ported to some new department of classi- fication, to be styled sulphides and nitrides, as we shall see in treating of salts.* The muriate of barytes crystallizes in ta- bles bevelled at the edges, or in octaedral pyramids applied base to base. It is solu- ble in five parts of water at 60 P , in still less at a boiling heat, and also in alcohol. It is not altered in the air, and but partly de- composable by heat. The sulphuric acid separates its base ; and the alkaline carbo- nates and sulphates decompose it by dou- ble affinity. It is best prepared by dis- solving the carbonate in dilute muriatic acid ; and if contaminated with iron or lead, which occasionally happens, these may be separated by the addition of a small quan- tity of liquid ammonia, or by boiling and stirring the solution with a little barytes. Mr. Goettling recommends to prepare it from the sulphate of barytes : eight parts of which in fine powder are to be mixed with two of muriate of soda, and one of charcoal powder. This is to be pressed hard into a Hessian crucible, and exposed for an hour and a half to a red heat in a wind furnace. The cold mass, being pow- dered, is to be boiled a minute or two in sixteen parts of water, and then filtered. To this liquor muriatic acid is to be added by little and little, till sulphuretted hydro- gen censes to be evolved; it is then to be filtered, a little hot water to be poured on the residuum, the liquor evaporated to a pellicle, filtered again, and then set to crys- iallize. As the muriate of soda is much more soluble than the muriate of baryta?, and does not separate by cooling, the mu- riate of barytes will crystallize into a per- fectly white salt, and leave the muriate of soda in the mother water, which may be evaporated repeatedly till no more muriate of barytes is obtained. This salt was first employed in medicine by Dr. Crawford, chiefly in scrofulous complaints and can- cer, beginning with doses of a few drops of the saturated solution twice a-day, and increasing it gradually, as far as forty or fifty drops in some instances. In large do- ses it excites nausea, and has deleterious effects. Fourcroy says it has been found very successful in scrofula in France. It has likewise been recommended as a ver- mifuge ; and it has been given with much apparent advantage, even to very young children, where the usual symptoms of worms occurred, though none were ascer- tained to be present. As a test of sulphu- ric acid it is of great use. The muriate of potash, formerly known by the names of febrifuge salt of Sylvius, digestive salt, and regenerated sea salt, crys- tallizes in regular cubes, or in rectangular parallelopipedons ; decrepitating on the fire, without losing much of their acid, and acquiring a little moisture from damp air, and giving it out again in dry. Their taste is saline and bitter. They are soluble in thrice their weight of cold water, and in but little less of boiling water, so as to re- quire spontaneous evaporation for crystal- lizing. Fourcroy recommends, to cover the vessel with gauze, and suspend hairs in it, for the purpose of obtaining regular crystals. It is sometimes prepared in decompo- sing sea salt by common potash for the purpose of obtaining soda; and may be formed by the direct combination of its constituent parts. It is decomposable by the sulphuric and nitric acids. Barytes decomposes it, though not completely. And both silex and alu- mina decomposed it partially in the dry way. It decomposes the earthy nitrates^ so that it might be used in saltpetre manu- factories to decompose the nitrate of lime. Muriate of soda, or common salt, is of con- siderable use in the arts, as well as a ne- cessary ingredient in our food. It crystal- lizes in cubes, which are sometimes group- ed together in various ways, and not unfre- quently form hollow quadrangular pyra- mids. In the fire it decrepitates, melts, and is at length volatilized. When pure it is not deliquescent. One part is soluble in 2$ of cold water, and in little less of hot, so that it cannot be crystallized but by eva- poration. According to M. Chenevix, it is soluble in alcohol also, particularly when it is mixed with the chlorate. Common salt is found in large masses, or ACI i in rocks under the earth, in England and elsewhere. In the solid form it is called sal gem or rock salt. If it be pure and trans- parent, it may be immediately used in the state in which it is found ; but if it contain any impure earthy particles, it should be previously freed from them. In some countries it is found in incredible quanti- ties, and dug up like metals from the bow- els of the earth. In this manner has this salt been dug out of the celebrated salt mines near Bochnia and Wieliczka, in Po- land, ever since the middle of the 13th century, consequently above these 500 years, in such amazing quantities, that sometimes there have been 20,000 tons ready for sale. In these mines, which are said to reach to the depth of several hun- dred fathoms, 500 men are constantly em- ployed. The pure and transparent salt needs no other preparation than to be beaten to small pieces, or ground in a mill. But that which is more impure must be elutriated, purified, and boiled. That which is quite impure, and full of small stones, is sold under the name of rock salt, and is applied to ordinary uses; it may ; likewise be used for strengthening weak and poor brine-springs. Though the salt mines of Wieliczka, | near Cracow in Poland, have long asto- | rushed the philosopher and traveller, yet it deserves to be remarked, that the quan- tity of rock salt obtained from the mines i of Northwich is greatly superior to that obtained at Cracow. The bishop of Llan- daff affirms, that a single pit, into which he descended, yielded at a medium 4000 I tons of salt in a year, which alone is about two-thirds of that raised in the Polish mines. This rock salt is never used on our tables in its crude state, as the Polish I rock salt is ; and though the pure transpa- rent salt might be used with our food, with- out any danger, yet it is prohibited under a penalty of 40s. for every pound of rock salt so applied. It is partly purified in i water, and a great part of it is sent to Li- verpool and other places, where it is used either for strengthening brine-springs or sea water. Beside the salt mines here mentioned, where the common salt is found in a con- crete state, under the name of rock salt, there is at Cordova, in the province of Ca- talonia in Spain, a remarkable solid moun- tain of rock salt ; this mountain is between four and five hundred feet in height, and a league in circuit; its depth below the sur- face of the earth is not known. This mountain contains the rock salt without the least admixture of any other matter. The waters of the ocean every where abound with common salt, though in diffe- rent proportions. The water of the Bal- trc sea is said to contain one sixty-fourth ACI of its weight of salt ; that of the sea be- tween England and Flanders contains one thirty-second part; that on the coast of Spain one sixteenth part; and between the tropics it is said, erroneously, to con- tain from an eleventh to an eighth part. The water of the sea contains, besides the common salt, a considerable propor- tion of muriate of magnesia, and some sul- phate of lime, of soda, and potash. The former is the chief ingredient of the re- maining liquid which is left after the ex- traction of the common salt,and is called the mother water. Sea water, if taken up neav the surface, contains also the putrid re- mains of animal substances, which render it nauseous, and in a long continued calm cause the sea to stink. The whole art of extracting salt from waters which contain it, consists in evapo- rating the water in the cheapest and most convenient manner. In England, a brine composed of sea water, with the addition of rock salt, is evaporated in large shallow iron boilers ; and the crystals of salt are tak en out in baskets. In Russia, and pro- bably in other northern countries, the sea water is exposed to freeze ; and the ice, which is almost entirely fresh, being taken out, the remaining brine is much stronger, and is evaporated by boiling. In the southern parts of Europe the salt-makers take advantage of spontaneous evapora- tion. A flat piece of ground near the sea is chosen, and banked round, to prevent its being overflowed at high water. The space within the banks is divided by low walls into several compartments, which successively communicate with each other. At flood tide, the first of these is filled with sea water; which, by remaining a certain time, deposites its impurities, and loses part of its aqueous fluid. The resi- due is then suffered to run into the next compartment; and the former is again filled as before. From the second com- partment, after a due time, the water is transferred into a third, which is lined with clay well rammed and levelled. At this period the evaporation is usually brought to that degree, that a crust of salt is formed on the surface of the water, which the workmen break, and it imme- diately falls to the bottom. They continue to do this, until the quantity is sufficient to be raked out, and dried in heaps. This is called bay salt. In some parts of France, and also on the coast of China, they wash the dried sand3 of the sea with a small proportion of wa- ter, and evaporate this brine in leaden boilers. There is no difference between this salt and the lake salt extracted from different lakes, excepting such as may be occasion- ed bv the casual intervention of some sub- ACI ACI stances. In this respect the Jeltonic salt water lake, in the Russian dominions, near Saratov? and Dmitrewsk, deserves our at- tention. In the year 1748, when the Rus- sians first fetched salt thence, the lake was almost solid with salt; and that to such a degree, that they drove their heavy wagons over it, as over a frozen river, and broke up the salt.f But since the year 1757 the water has increased so much, that at this time it is nothing more than a lake very strongly impregnated with salt. The Jeltonic lake salt contains at the same time alum and sulphate of magnesia. At several places in Germany, and at Montmarot in France, the waters of salt springs are pumped up to a large reser- voir at the top of a building or shed ; from which it drops or trickles through small apertures upon boards covered with brush- wood. The large surface of the water thus exposed to the air causes a very con- siderable evaporation ; and the brine is af- terward conveyed to the boilers for the perfect separation of the salt. To free common salt from those mix- tures that render it deliquescent, and less fit for the purposes to which it is applied, it may be put into a conical vessel with a small aperture at the point, and a satura- ted solution of the muriate of soda boiling hot be poured on i f . This solution will dissolve and carry oil any other salt mix- ed with the muriate of soda, and leave it quite pure, by repeating the process three l>r four times. From this salt, as already observed, the muriatic acid is extracted; and of late years to obtain its base separate, in the most economical mode, for the purposes of the arts, has been an object of research. The process of Scheele, which consists in mixing the muriate of soda with red oxide of lead, making this into a soft paste with water, and allowing 1 it to stand thus for some time, moistening it with water as it gets dry, and then separating the soda from the muriate of lead by lixiviation, has been resorted to in this country. Mr. Turner some years ago had a patent for it; converting the muriate of lead into a a pigment, which was termed mineral or patent yeko-w, by heating it to fusion. The oxide of lead should be at least twice the weight of the salt. This would have an- swered extremely well, had there been an adequate and regular demand for the pigment. At present, we understand, the greater part of the carbonate of soda in the market is furnished by decomposing the sulphate of soda left after the muriatic f Why did it not sink? Does salt swim like ice ? I question the truth of this ac- co ant. acid is expelled in the usual way of manu- facturing it from common salt. Various processes for this purpose were tried in France and made public by the French government, all depending on the princi- ple of decomposing the acid of the sul- phate, by charcoal, and at the same time adding some other material to prevent the soda from forming a sulphuret. What they consider as the best, is to mix the sul- phate of soda with an equal weight of chalk and rather more than half its weight oi charcoal powder, and to expose the mix- ture in a reverberatory furnace to a heat sufficient to bring them to a state of im- perfect liquefaction. Much of the sulphuz formed will be expelled in vapour and burned, the mixture being frequently stirred to promote this ; and this is conti- nued till the mass on cooling assumes a fine grain. It is then left exposed to a humid atmosphere, and the carbonate of soda may be extracted by lixiviation, the sulphur not consumed having united with the lime. Tinmen's shreds, or old iron, may be employed instead of chalk, in the proportion of 65 parts to 200 of sulphate of soda, and 62 of charcoal ; or chalk and iron may be used at the same time in dif- ferent proportions. The muriate of soda might be decomposed in the first instance by the sulphate of iron, instead of the sul- phuric acid. The carbonate of soda thus prepared, however, is not free from sul- phur, and Dize recommends the abstrac- tion of it by adding litharge to the lixi- vium in a state of ebullition, which will render the alkali pure. Oxide of manga- nese was substituted in the same way with equal success ; and this may be used re- peatedly, merely by calcining it after each time to expel the sulphur. .Mr. Accum gives the following method, as having answered extremely well in a soda manufactory in which he was em- ployed : Five hundred pounds of sulphate of soda, procured from the bleachers, who make a large quantity in preparing their muriatic acid from common salt, were put into an iron boiler with a sufficient quan- tity of soft water. Into another boiler were put 560 Ibs. of good American potash, or 570, if the potash were indifferent, dis- solved in about 30 pails of water, or as lit- tle as possible. When both were brought to boil, the solution of potash was ladled into that of sulphate of soda, agitating the, mixture, and raising the fire as quickly as possible. When the whole boiled, it \vas ladled into a wooden gutter, that convey- ed it to a wooden cistern lined with lead near half an inch thick, in a cool place. Sticks were placed across the cistern, from which slips of sheet lead, two or three inches wide, hung down into the fluid about four inches distant from each ACI AGI other. When the whole was cold, which in winter was in about three days, the fluid was drawn off, the crystalized salt was de- tached from the slips of lead, and the rock of salt fixed to the bottom was separ- ated by a chisel and mallet. The salt being washed in the same cistern, to free it from impurities, was then returned to the boil- er, dissolved in clear water, and evaporat- ed till a strong 1 pellicle formed. Letting 1 it cool till the hand could be dipped into it, it was kept at this temperature as long- as pellicles would form over the whole sur- face, and fall to the bottom. When no more pellicles appeared without blowing on the surface, the fire was put out, and the solution returned into the cistern to crystallize. If the solution be suffered to cool pretty low, very little sulphate of potash will be found mixed with the soda; but the rocky masses met with in the mar- ket generally contain a pretty large quan- tity. Tn the process above described, the produce of the mixed salt from 100 Ibs. of sulphate of soda was in general from 136 i to 139 Ibs. Besides its use in seasoning 1 our food, and preserving- meat both for domestic |i consumption and during" the longest voy- j: ages, and in furnishing us with the muri- | atic acid and soda, salt forms a glaze for i coarse pottery, by being thrown into the I oven where it is baked ; it improves the whiteness and clearness of glass ; it gives i greater hardness to soap ; in melting me- j tals it preserves their surface from calci- nation, by defending them from the air, and is employed with advantage in some assays ; it is used as a mordant, and tor im- proving certain colours, and enters more or less into many other processes of the , arts. The muriate of strontian has not long been known. Dr. Hope first distinguished it from muriate of barytes. It crystallizes in very slender hexagonal prisms, has a cool pungent taste, without the austerity { of the muriate of barytes, or the bitterness 1 of the muriate of lime ; is soluble in 0.75 of water at 60, and to almost any amount in boiling water ; is likewise soluble in alcohol, and gives a blood-red colour to its flame. It has never been found in nature, but 1 may be prepared in the same way as the muriate of barytes. The muriate of lime has been known by the names of marine selenite, calcareous marine salt, muria, and fixed sal ammoniac, It crystallizes in hexaedral prisms, termi- nated by acute pyramids ; but if the solu- tion be greatly concentrated, and exposed to a low temperature, it is condensed in confused bundles of neeclly crystals. Its taste is acrid, bitter, and very disagreea- ble. It is soluble in half its weight of cold Vox. i, [ 9 ] water, and by heat in its own water of crystallization. It is one of the most de- liquescent salts known ; and when deli- quesced has been called oil of lime. It exists in nature, but neither very abun- dantly nor very pure. It is formed in chemical laboratories, in the decomposi- tion of muriate of ammonia; andHomberg found, that, if it were urged by a violent heat, till it condensed, on cooling, into a vitreous mass, it emitted a phosphoric light upon being struck by any hard body, in which state it was called ffombei^g's phos- phorus. Hitherto it has been little used except for frigorific mixtures ; and with snow it produces a very great degree of cold. Fourcroy, indeed, says he has found it of great utility in obstructions of the lym- phatics, and in scrofulous affections. The muriate of ammonia has long been known by the name of sal ammonia, or am- monia. It is found native in the neigh- bourhood of volcanoes, where it is sub- limed sometimes nearly pure, and in dif- ferent parts of Asia and Africa. A great deal is carried annually to Russia and Si- beria from Bucharian Tartary ; and we formerly imported large quantities from, Egypt, but now manufacture it at home. See AMMONIA. This salt is usually in the form of cakes, with a convex surface on one side, and concave on the other, from being sub- limed into large globular vessels ; but by solution it may be obtained in regular quadrangular crystals. It is remarkable for possessing a certain degree of ductili- ty, so that it is not easily pulverable. It is soluble in 3| parts of water at 60, and in little more than its own weight of boil- ing water. Its taste is cool, acrid, and bit- terish. Its specific gravity is 1.42. It attracts moisture from the air but very slightly. Muriate of ammonia has been more em- ployed in medicine than it is at present. It is sometimes useful as an auxiliary to the bark in intermittents ; in gargles it is beneficial, and externally it is a good dis- cutient. In dyeing it improves or height- ens different colours. In tinning and sol- dering it is employed to preserve the sur- face of the metals from oxidation. In as- saying it discovers iron, and separates it from some of its combinations. The muriate of magnesia is extremely deliquescent, soluble in an equal weight of water, and difficultly crystallizable It dis- solves also in five parts of alcohol. It is decomposable by heat, which expels its acid. Its taste is intensely bitter. With ammonia this muriate forms a tri- ple salt, crystallizable in little polyedrons, which separate quickly from the water, but are not very regularly formed. Us ACI AC1 taste partakes of that of both the prece- ding- salts. The best mode of preparing 1 it, is by mixing a solution of 27 parts of muriate of ammonia with a solution of 73 of muriate of magnesia; but it may be formed by a semi-decomposition of either of these muriates by the base of the other. It is decomposable by heat, and requires six or seven times its weight of water to di 'Solve it. Of the muriate of glucine we know but little. It appears to crystallize *n very small crystals; to be decomposable by heat ; and, dissolved in alcohol and diluted with water, to form a pleasant saccharine liquor. Muriate of alumina is scarcely crystal- lizable, as on evaporation it assumes the state of a thick jelly. It has an acid, styp- tic, acrid taste. It is extremely soluble in water, and deliquescent. Fire decom- poses it. It may be prepared by directly combining the muriatic acid with alumina, but the acid always remains in excess. The muriate of zircon crystallizes in small needles, which are very soluble, at- tract moisture, and lose their transparency In the air. It has an austere taste, with somewhat of acrimony. It is decomposa- ble by heat. The gallic acid precipitates from its solution, if it be free from iron, a white powder. Carbonate of ammonia, if added in excess, redissolves the preci- pitate it had before thrown down. Muriate of yttria does not crystallize when evaporated, but forms a jelly : it dries with difficulty, and deliquesces. Fourcroy observes, that when siliceous stones, previously fused with potash, are treated with muriatic acid, a limpid solu- tion is formed, which may be reduced to a transparent jelly by slow evaporation. But a boiling heat decomposes the sili- ceous muriate, and the earth is deposited. The solution is always acid. * ACID (MURIATIC, OXYGENATED). See CHLORIXE.* * ACID (MURIATIC, OXYGEXIZKD). This supposed acid was lately described by M. Thenard. Fie saturated common muriatic acid of moderate strength with deutoxide of barium, reduced into a soft paste by trituration with water. He then precipi- tated the barytes from the liquid, by ad- ding the requisite quantity of sulphuric acid. He next took this oxygenized mu- riatic acid, and treated it with deutoxide of barium and sulphuric acid, to oxygenate it anew. In this way he charged' it with oxygen as often as 15 times. He thus ob- tained a liquid acid which contained 32 times its volume of oxygen at the tempe- rature of 68 Fahr. and at the ordinary atmospherical pressure, and only 4 times its volume of muriatic acid, which gives about 28 equivalent primes of oxygen to one of muriatic acid. For the ratio of oxygen to the acid, by weight, is 1. to 4.6 ; b.ut by measure the ratio will be as these two numbers respectively divided by the specific gravity of the gases, or as y.7 TT to -j-.TT^'Which by reduction makes near; ly one volume of oxygen, equivalent to four of muriatic acid. Now, the oxygen in the above result, instead of being 1 4th of the volume of the acid gas, was seven times greater, whence we derive the num- ber 28. Still more oxygen may however be added. On putting the above oxygen- ized acid in contact with sulphate of sil- ver, an insoluble chloride of this metal subsides, and the liquid is oxygenized sulphuric acid. When this is passed through the filter, muriatic acid is added to it, but in smaller quantity than existed in the original oxygenized acid. A quan- tity of barytes, just sufficient to precipi- tate the sulphuric acid, is then added. In- stantly the oxygen, leaving the sulphuric acid to unite with the muriatic acid, brings that acid to the highest point of oxygena- tion. Thus we see that we can transfer the whole of the oxygen from one of these acids to the other ; and on a little reflection it will be evident, that to obtain sulphuric acid in the highest degree of oxygenation, it will be merely necessary to pour barytes water into oxygenated sulphuric acid, so as to precipitate only a part of the acid. All these operations, with a little prac- tice, may be performed without the least difficulty. By combining the two methods just described, M. Thenard found that lie could obtain oxygenized muriatic acid, containing nearly 16 times as many vo- lumes of oxygen as of muriatic acid, which represents about 64 equivalent primes of the former to one of the latter. This oxygenized acid leaves no residuum when evaporated. It is a very acid, colourless liquid, almost destitute of smell, and pow- erfully reddens turnsole. When boiled for some time, its oxygen is expelled. It dissolves zinc without effervescence. Its action on the oxide of silver is curious. These two bodies occasion as lively an ef- fervescence as if an acid were poured upon a carbonate. Water and a chloride are formed, while the oxygen is evolved. This oxide enables us to determine the quantity of oxygen present in the oxygen- ized acid. Pour mercury into a graduated glass tube, leaving a small determinate space, which must be filled with the above acid, invert the tube in mercury, let up oxide of silver diffused in water ; instantly the oxygen is separated. We ought, however, to regard this ap- parent oxygenation of the acid, merely as the conversion of a portion of its com- ACI ACI Mined water into deutoxide of hydrogen. The same explanation maybe extended to the other oxygenized acids of M. Thenard. See WATER.* * ACID (CHLORIC). We place this acid after the muriatic acid, because it has chlorine also for its base. It was first eli- minated from the salts containing it by M. Gay-Lussac, and described by him in his admirable memoir on iodine, published in the 91st volume of the Jttmales de Chimie. When a current of chlorine is passed for some time through a solution of barytic ber is however too great, in consequence of estimating the specific gravity of oxy- gen 1.1111, while M. Gay-Lussac makes it 1.10359. Chloric acid is at any rate a com- pound of 5 primes of oxygen + 1 of chlo- rine = 5. -f- 4.43 by Bcrzelius, or 5. -f 4.45 by Dr. Ure's estimate of the atom of chlorine. M. Vauquelin, in making phosphate of silver act on the mixed saline solution above described, tried to accelerate its action by dissolving it previously in acetic acid. But on evaporating the chlorate of earth in warm water, a substance called barytes so obtained to dryness, and ex- hyperoxymuriate of barytes by its first posing about 30 grains to a decomposing discoverer, M. Chenevix, is formed, as heat, a tremendous explosion took place, well as some common muriate. The lat- which broke the furnace, rent a thick ter is separated, by boiling phosphate of platina crucible, and drove its lid into the silver in the compound solution. The for- chimney, where it stuck. It was the em- mer may then be obtained by evaporation, ployment of acetic acid which occasioned in fine rhomboidal prisms. Into a dilute this accident, and therefore it ought never solution of this salt, M. Gay-Lussac poured weak sulphuric acid. Though he added only a few drops of acid, not nearly enough to saturate the barytes, the liquid became sensibly acid, and not a bubble of oxygen escaped. By continuing to add sulphuric acid with caution, he succeeded in obtain- ing an acid liquid entirely free from sul- phuric acid and barytes, and not precipi- tating nitrate of silver. It was chloric acid dissolved in water. Its characters are the following. This acid has no sensible smell. Its so- lution in water is perfectly colourless. Its taste is very acid, and it reddens litmus without destroying the colour. It produces no alteration on solution of indigo in sul- phuric acid. Light does not decompose it. It may be concentrated by a gentle heat, without undergoing decomposition, or without evaporating. It was kept a long time exposed to the air without sensible diminution of its quantity. When con- centrated, it has something of an oily con- sistency. When exposed to heat, it is partly decomposed into oxygen and chlo- rine, and partly volatilized without altera- tion. Muriatic acid decomposes it in the same way, at the common temperature. Sulphurous acid, and sulphuretted hydro- gen, have the same property; but nitric acid produces no change upon it. Com- bined with ammonia, it forms a fulminating salt, formerly described by M. Chenevix. It does not precipitate any metallic solu- tion. It readily dissolves zinc, disengaging hydrogen ; but it acts slowly on mercury. It cannot be obtained in the gaseous state. It is composed of 1 volume chlorine -{- 2.5 oxygen, or, by weight, of 100 chlorine -f- 111.70 oxygen, if we consider the spe- to be used in this way. To the preceding account of the pro- perties of chloric acid, M, Vauquelin has added the following : Its taste is not only acid, but astringent, and its odour, when concentrated, is somewhat pungent. It differs from chlorine, in not precipitating gelatin. When paper stained with litmus is left for rfome time in contact with it, the colour is destroyed. Mixed with muriatic acid, water is formed, and both acids are converted into chlorine. Sulphurous acid is converted into sulphuric, by taking oxy- gen from the chloric acid, which is con- sequently converted into chlorine. Chloric acid combines with the bases, and forms the chlorates, a set of salts for- merly known by the name of the hyperoxy- genized muriates. They may be formed either directly by saturating the alkali or earth with the chloric acid, or by the old process of transmitting chlorine through the solutions of the bases, in Woulfe's bottles. In this case the water is decom- posed. Its oxygen unites to one portion of the chlorine, forming chloric acid, while its hydrogen unites to another portion of chlorine, forming muriatic acid ; and hence, chlorates and muriates must be contemporaneously generated, and must be afterwards separated by crystalliza- tion, or peculiar methods. The chlorate of potash, or hyperoxymu- riate, has been long known. When ex- posed to a red heat, 100 grains of this salt yield 38.88 of oxygen, and are converted into the chloride of potassium, or the dry muriate. This remainder of 61.12 grains consists of 32.19 potassium and 28.93 chlo- rine. But 32.19 potassium require 6.50 cific gravity of chlorine to be 2.4866. But oxygen, to form the potash which existed if it be called 2.420, as M. Gay-Lussac does in the original chlorate. Therefore, sub- in his memoir, it will then come out 100 tracting this quantity from 38. 88, we have Chlorine -f- 114.7 oxygen. This last num- 32.38 for the oxygen combined with the ACI AC1 chlorine, constituting 61.31 of chloric acid, to 38.69 of potash.* To its compounds we shall proceed, premising 1 , that we are indebted to M. Chenevix for the first accurate descrip- tion of the chlorates, orhyperoxymuriates. Chlorate, or hyperoxy muriate of potash, may be procured by receiving chlorine, as it is formed, into a solution of potash. When the solution is saturated, it may be evaporated gently, and the first crystals produced will be the salt desired, this crystallizing before the simple muriate, which is produced at the same time with it. Its crystals are in shining hexaedral laminae, or rhomboidal plates. It is solu- ble in 17 parts of cold water ; and, but very sparingly, in alcohol. * Its taste is cooling, and rather unpleasant. Its speci- fic gravity is 2.0. 16 parts of water, at 60, dissolve one of it, and 2 of boiling water. The purest oxygen is extracted from this salt, by exposing it to a gentle red heat. One hundred grains yield about 115 cubic inches of gas. It consists of 9.45 chloric acid -|- 5.95 potash = 15.4, which is the prime equivalent of the salt.* It is not de- composed by the direct rays of the sun. Subjected to distillation in a coated retort, it first fuses, and on increasing the heat, gives out oxygen gas. It is incapable of discharging vegetable colours; but the addition of a little sulphuric acid developes this property. So likewise a few grains of it, added to an ounce of muriatic acid, give it this property. It is decomposed by the sulphuric and nitric acids. If a few grains be dropped into strong sulphuric acid, an of- fensive smell is produced, resembling that of a brick-kiln, mixed with that of nitrous gas ; and if the quantity be large enough, an explosion will en c ue. If the vessel be deep, it will be filled with a thick, heavy vapour, of a greenish yellow colour, but not producing the symptoms of catarrh, at least in so violent a degree as the fumes of chlorine. Underneath this vapour is a bright orange-coloured fluid. This vapour inflames alcohol, oil of turpentine, cam- phor, resin, tallow, elastic gum, and some other inflammable substances, if thrown into it. If the sulphuric acid be poured upon the salt, a violent decrepitation takes place, sometimes, though rarely, accom- panied by a flash. M. Chenevix attempted to disengage the chloric acid from this salt, by adding sulphuric acid to it in a re- tort ; but almost as soon as the fire was kindled, an explosion took place, by which a French gentleman present was severely wounded, and narrowly escaped the loss of an eye. The effects of this salt on inflammable bodies are very powerful. Rub two grains into powder in a mortar, add a grain of sul- phur, mix them well by gentle trituration, then collect the powder into a heap, and press upon it suddenly and forcibly with the pestle, a loud detonation will ensue. If the mixture be wrapped in strong pa- per, and struck with a hammer, the report will be still louder. Five grains of the salt, mixed in the same manner with two and a half of charcoal, will be inflamed by strong trituration, especially if a grain or two of sulphur be added, but without much noise. If a little sugar be mixed with half its weight of the chlorate, and a little strong sulphuric acid poured on it, a sudden and vehement inflammation will ensue ; but this experiment requires caution, as well as the following. To one grain of the pow- dered salt in a mortar, add half a gram of phosphorus, it will detonal e, with a loud report, on the gentlest trituration. In this experiment the hand should be defended by a glove, and great care should be taken that none of the phosphorus get into the eyes. Phosphorus may be inflamed by it under water, by putting into a wine glass one part of phosphorus and two of the chlo- rate, nearly filling the glass with water, and then pouring in through a glass tube reaching to the bottom, three or four parts of sulphuric acid. This experiment, too, is very hazardous to the eyes. If olive or linseed oil be taken instead of phosphorus, it maybe inflamed by similar means on the surface of the water. This salt should not be kept mixed with sul- phur, or perhaps any inflammable sub- stance, as in this state it has been known to detonate spontaneously. As it is the common effect of mixtures of this salt with inflammable substances of every kind, to take fire on being projected into the stron- ger acids, M. Chenevix tried the experi- ment with it mixed with diamond powder in various proportions, but without success. Chlorate of soda may be prepared in the same manner as the preceding, by sub- stituting soda for potash ; but it is not easy to obtain it separate, as it is nearly as so- luble as the muriate of soda, requiring on- ly 3 parts of cold water. * Vauquelin formed it, by saturating chloric acid with soda ; 500 parts of the dry carbonate yield- ing 1 !00 parts of crystallized chlorate. It consists of 3.95 soda -\- 9.45 acid = 13.4, which is its prime equivalent.* It crystal- lizes in square plates, produces a sensation of cold in the mouth, and a saline taste ; is slightly deliquescent, and in its other properties resembling the chlorate of pot- ash. Barytes appears to be the next base in order of affinity for this acid. The best method of forming it is to pour hot water on a large quantity of this earth, and to pass a current of chlorine through the liquid kept warm, so that a fresh portion of barytes may be taken up as the former ACI ACI is saturated. This salt is soluble in about four parts of cold water, and less of warm, and crystallizes like the simple muriate. It may be obtained, however, by the agen- cy of double affinity ; for phosphate of silver boiled in the solution will decom- pose the simple muriate, and the muriate of silver and phosphate of barytes being- insoluble, will both fall down and leave the chlorate in solution alone. The phos- phate of silver employed in this process must be perfectly pure, and not the least contaminated with copper. The chlorate of strontites may be obtain- ed in the same manner. It is deliquescent, melts immediately in the mouth and pro- duces cold ; is more soluble in alcohol than the simple muriate, and crystallizes in needles. The chlorate of lime, obtained in a si- milar way, is extremely deliquescent, li- quefies at a low heat is very soluble in alcohol, produces much cold in solution, and has a sharp bitter taste. Chlorace of ammonia is formed by dou- ble affinity, the carbonate of ammonia de- composing 1 the earthy salts of this genus, giv.ig up its carbonic acid to their base, and combining with their acid into chlo- rate of ammonia, which may be obtained by evaporation. It is very soluble both in water and alcohol, and decomposed by a moderate heat. The chlorate of magnesia much resem- bles that of lime. To obtain chlorate of alumina, M. Chene- vix put some alumina, precipitated from the muriate, and well washed, but still moist, into a Woulfe's apparatus, and treat- ed it as the other earths. The alumina shortly disappeared ; and on pouring sul- phuric acid into the liquor, a strong smell i of chloric acid was perceivable ; but on at- tempting to obtain the salt pure by means of phosphate of silver, the whole was de- composed, and nothing but chlorate of silver was found in the solution. M. Chene- ! vix adds, however, that the aluminous salt appears to be very deliquescent, and so- luble in alcohol. * Acin (PERCHLORIC). If about 3 parts of sulphuric acid be poured on one of chlo- rate of potash in a retort, and after the first violent action is over, heat be gradu- ally applied, to separate the deutoxide of chlorine, a saline mass will remain, con- sisting of bisulphate of potash and per- chlorate of potash. By one or two crystal- lizations, the latter salt may be separated from the former. It is a neutral salt, with a taste somewhat similar to the common muriate of potash. It is very sparingly so- luble in cold water, since at 60, only j-^ is dissolved; but in boiling water it is more soluble. Its crystals are elongated octahe- drons. It detonates feebly when triturated with sulphur in a mortar. At the heat of 412, it is resolved into oxygen and muri- ate of potash, in the proportion of 46 of the former to 54 of the latter. Sulphuric acid, at 280, disengages the perchloric ucid. For these facts science is indebted to Count Von Stadion. It seems to consist of 7 primes of oxygen, combined with 1 of chlorine, or 7.0 -|- 4.45. These curious discoveries has been lately verified by Sir H Davy. The other perchlorates are not known. Before leaving the acids of chlorine, we shall describe the ingenious method em- ployed by Mr. Wheeler to procure chloric acid from the chlorate of petash. He mix- ed a warm solution of this salt with one of fluosilicic acid. He kept the mixture mo- derately hot for a few minutes, and to en- sure the perfect decomposition of the salt, added a slight excess of the acid.. Aque- ous solution of ammonia will show, by the separation of silica, whether any of the fluosilicic acid be left after the decompo- sition of the chlorate. Thus we can effect its complete decomposition. The mixture becomes turbid, and fluosilicate of potash is precipitated abundantly in the form of a gelatinous mass. The supernatant liquid will then contain nothing but chloric acid, contaminated with a small quantity of fluo- silicic. This may be removed by the cau- tious addition of a small quantity of solu- tion of chlorate. Or after filtration, the whole acid may be neutralized by carbo- nate of barytes, and the chlorate of that earth being obtained in crystals, is employ- ed to procure the acid, as directed by M. Gay-Lussac.* ACID (NiTiuc.) The two principal con- stituent parts of our atmosphere, when in certain proportions, are capable, under particular circumstances, of combining chemically into one of the most powerful acids, the nitric. If these gases be mixed in a proper proportion in a glass tube about a line in diameter, over mercury, and a se- ries of electric shocks be passed through them for some hours, they will form nitric acid; or, if a solution of potash be present with them, nitrate of potash will be obtain- ed. The constitution of this acid may be further proved, analytically, by driving it through a red hot porcelain tube, as thus it will be decomposed into oxygen and ni- trogen gases. For all practical purposes, however, the nitric acid is obtained from nitrate of potash, from which it is expelled by sulphuric acid. Three parts of pure nitrate of potash,f coarsely powdered, are to be put into a glass retort, with two of strong sulphu- f Deprived of its water of crystalliza- tion by heating it nearly red hot in an iron pan. ACI ACI ric acid. This must be cautiously added, taking 1 care to avoid the fumes that arise. Join to the retort a tubulated receiver of large capacity, with an adopter interposed, and lute the junctures with glazier's put- ty. In the tubulure fix a glass tube, ter- minating in another large receiver, in which is a small quantity of water; and, if you wish to collect the gaseous products, let a bent glass tube from this receiver communicate with a pneumatic trough. Apply heat to the retort by means of a sand bath. The first product that passes into the receiver is generally red acd fu- ming; but the appearances gradually di- minish, till the acid comes over pale, and even colourless, if the materials used were clean. After this it again becomes more and more red and fuming, till the end of the operation ; and the whole mingled to- gether will be of a yellow or orange colour. * Empty the receiver, and again replace it. Then introduce by a small funnel, ve- ry cautiously, one part of boiling water in a slender stream, and continue the distilla- tion. A small quantity of a weaker acid will thus be obtained, which can be kept apart. The first will have a specific gra- vity of about 1.500, if the heat have been properly regulated, and if the receiver was refrigerated by cold water or ice. Acid of that density, amounting to two-thirds of the weight of the nitre, may thus be pro- cured. But commonly the heat is pushed too high, whence more or less of the acid is decomposed, and its proportion of water uniting to the remainder, reduces its strength. It is not profitable to use a smaller proportion of sulphuric acid, when a concentrated nitric is required. But when only a dilute acid, called in com- merce aquafortis, is required, then less sulphuric acid will suffice, provided a por- tion of water be added. One hundred parts of good nitre, sixty of strong sulphu- ric acid, and twenty of water, form econo- mical proportions.* In the large way, and for the purposes of the arts, extremely thick cast iron or earthen retorts are employed, to which an earthen head is adapted, and connected with a range of proper condensers. The strength of the acid too is varied, by put- ting more or less water in the receivers. The nitric acid thus made generally con- tains sulphuric acid, and also muriatic, from the impurity of the nitrate employed. If the former, a solution of nitrate of bary- tes will occasion a white precipitate ; if the latter, nitrate of silver will render it milky. The sulphuric acid may be sepa- rated by a second distillation from very pure nitre, equal in weight to an eighth of that originally employed; or by preci- pitating with nitrate of barytes, decanting the clear liquid, and distilling it. The mu- riatic acid may be separated by proceed- ing in the same way with nitrate of silver, or with litharge, decanting the clear li- quor, and re -distilling it, leaving an eighth or tenth part in the retort. The acid for the last process should be condensed as much as possible, and the re-distillation conducted very slowly; and if it be s\op- ped when half is come over, beautiful crys- tals of muriate of lead will be obtained on cooling the remainder, if litharge be used, as M. Steinacher informs us; who also adds, that the vessels should be made to fit tight by grinding, as any lute is liable to contaminate the product. As this acid still holds in solution more or less nitrous gas, it is not in fact nitric acid, but a kind of nitrous : it is therefore necessary to put it into a retort, to which a receiver is added, the two vessels not being luted, and to apply a very gentle heat for several hours, changing the re- ceiver as soon as it is filled with red va- pours. The nitrous gas will thus be ex- pelled, and the nitric acid will remain in the retort as limpid and colourless as wa- ter. It should be kept in a bottle secluded from the light, otherwise it will lose part of its oxygen. "What remains in the retort is a bisul- phate of potash, from which the superflu- ous acid may be expelled by a pretty strong heat, and the residuum, being dissolved and crystallized, will be sulphate of potash. As nitric acid in a fluid state is always mixed with water, different attempts have been made to ascertain its strength, or the quantity of real acid contained in it. Mr. Kirwan supposed, that the nitrate of soda contained the pure arid undiluted with wa- ter, and thus calculated its strength from the quantity requisite to saturate a given portion of soda. Sir LI. Davy more recent- ly took the acid in the form of gas as the standard, and found how much of this is contained in an acid of a given specific gravity in the liquid state. * Mr. Kirwan gave 68 as the quantity of real acid in 100 of the liquid acid of speci- fic gravity 1.500; Sir H. Davy's determi- nation was 91 ; Dr. Wollaston's, as infer- red from the experiments of Mr. R. Philips, 75 ; and Mr. Dalton's corrected result from Kirwan's table, was 68. In this state of discordance Dr. Ure performed a series of experiments, with the view of determining the constitution of liquid nitric acid, and published an account of them, with some new tables, in the fourth and sixth vo- lumes of the Journal of Science and the Arts. From regular prisms of nitre, he procur- ed by slow distillation, with concentrated oil of vitriol, nitric acid; which by the tests of nitrates of silver and of barytes, was found to be pure. Only the first portion ACI ACI that came over was employed for the ex- periments. It was nearly colourless, and had a specific gravity of 1.500. A re-dis- tilled and colourless nitric acid, prepared in London, was also used for experiments of verification, in estimating 1 the quantity ef dry acid in liquid acid of a known den- sity. The above acid of 1.500 being mixed in numbered phials, with pure water, in the different proportions of 95 -f- 5, 90 -{- 10, 80 -f- 20, &c. he obtained, after due agita- tion, and an interval of 24 hours, liquids whose specific gravities, at 60 Fahren- heit, were determined by means of an ac- curate balance, with a narrow-necked glass globe of known capacity. By considering the series of numbers thus obtained, he discovered the geometrical law which re- gulates them. The specific gravity of di- lute acid, containing 10 parts in the 100 of that whose density is 1.500, is 1.054. Ta- king this number as the root, its successive powers will give us the successive densi- ties, at the terms of 20, 30, 40, &c. per cent. Thus 1.0542 ^ l.m is the speci- fic gravity corresponding to 20 of the strong liquid acid -f 80 water; 1.0543 _ 1.171 is that for 30 per cent, of strong acid ; 1.0544 = 1.^34 is the specific gravity at 40 per cent. The specific gravities are therefore a series of numbers in geometri- cal prog'ression, corresponding to the terms of dilution, another series in arithmetical progression, exactly as he had shown in the 7th number of the Journal of Science with regard to sulphuric acid. Hence if one term be given, the whole series may be found. On uniting the strong acid with water, a considerable condensation of vo- lume takes place. The maximum conden- sation occurs, when 58 of acid are mixed with 42 of water. Above this point, the curve of condensation has a contrary flex- ure ; and therefore a small modification must be made on the root 1.054, in order to obtain with final accuracy, in the higher part of the range, the numerical powers which represent the specific gravities. The modification is however very simple. To obtain the number for 50 per cent, the root is 1.053 ; and for each decade up to 70, the root must be diminished by 0,002. Thus for 60, it will become 1.051, and for 70, 1.049. Above this we shall obtain a precise correspondence with experiment, up to 1.500 sp. gravity, if for each succes- sive decade we subtract 0.0025 from the last diminished root, before raising it to the desired power, which represents the per centage of liquid acid. It is established by the concurring ex- periments of Sir II. Davy and M. Gay-Lus- sac, that dry nitric acid is a compound of 2 volumes of oxygen combined with 1 of nitrogen ; of which the weights are 2.5 X 1.1U = 2.777 for the proportion of oxygen, and 0.9722 for that of nitrogen ; and in 100 parts, of 73^ of the former -f- 263 of the latter. But nitrogen combines with several inferior proportions o-: oxy- gen, which are all multiples of its prime equivalent 1.0; and the present compound is exactly represented by making 1 prime of nitrogen = 1.75, and 5 of oxygen = 5.0 ; whence the acid prime is the sum of these two numbers, or 6.75. Now this re- sult deduced from its constituents, coin- cides perfectly with that derived from the quantity in which this acid saturates defi- nite quantities of the salifiable bases, pot- ash, soda, lime, &c. There can be no doubt, therefore, that the prime equiva- lent of the acid is 6.75 ; and as little that it consists of 5 parts of oxygen and 1.75 of nitrogen. Possessed of these data, we may perhaps see some reason why the greatest condensation of volume, in diluting strong liquid acid, should take place with 58 of it, and 42 of water. Since 100 parts of acid of 1.500 contain, by Dr. Ure's expe- riments, 79.7 of dry acid, therefore acid of, the above dilution will contain 46 dry acid, and 54 water ; or reducing the numbers to prime proportions, we have the ratio of 6.75 to 7.875, being that of one prime of real acid to 7 primes of water. But we have seen that the real acid prime, is made up of 1 of nitrogen associated by chemical affinity with 5 of oxygen. Now imagine a figure, in which the central prime of ni- trogen is surrounded by 5 of oxygen. To the upper and under surface of the nitro- gen let a prime of water be attached ; and one also to each of the primes of oxygen. We have thus the 7 primes distributed in the most compact and symmetrical man- ner. By this hypothesis, w r e can understand how the elements of acid and water may have such a collocation and proportion, as to give the utmost efficacy to their reci- procal attractions, whence the maximum condensation will result. A striking analo- gy will be found in the dilution of sulphu- ric acid. If on 58 parts by weight of acid of 1.500, we pour cautiously 42 of water in a graduated measure, of which the whole occupies 100 divisions, and then mix them intimately, the temperature will rise from 60 to 140, and after cooling to 60 again, the volume will be found only 92.65. No other proportion of water and acid causes the evolution of so much heat. When 90 parts of the strong acid are united with 10 of water, 100 in volume become 97; and Aviien 10 parts of the same acid are com- bined with 90 of water, the resulting vo- lume is 98. It deserves notice, that 80 of acid -f- 20 water, and 30 of acid -4- 70 wa- ter, each gives a dilute acid, whose degree of condensation is the same, namely, 100 measures become 94.8, ACI ACI TABLE of Nitric Acid, by Dr. Sp.Gr. Jjiq. Add in 100 Dry Acid in 100. Sp.Gr. Liq. Jlcid in 100 Dry Acid in 100. Sp.Gr. Liq. Dry Acid Acid n 100 'in 100. Sp.Gr. Liq. Acid in 100 Dry Acid in 100. 1.5000 100 79.700 1.4189 75 59.775 1.2947 5>J 39.850 1.1403 25 19.925 1.4980 99 78.903 1.4147 74 58.978 1.2887 49 39.053 .1345 24 19.128 1.4960 98 78.106 1.4107 73 58.181 i.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 1.2705 46 35.662 1.1168 21 16.737 1.4830 95 75.715 1.3978 70 55.790 1.2644 45 35.865 1.1109 20 15.940 1.4850 94 74.918 1.3945 69 54.993 1.2583 44 35.068 1.1051 19 15.143 1.4820 93 74.121 1.3882 68 54.196 1.252.) 43 34.271 1.0993 la 14.346 1.4790 92 73.324 1.3833 67 53.399 1.2462 42 33.474 1 1.0935 17 13.549 1.4760 91 72.527 1.3783 66 52.602 1.2402 41 32.677 1.0878 16 12.752 1.4730 90 71.730 1.3732 65 51.805 1.2341 40 31.880 1.0821 15 11.955 1.4700 89 70.933 1.3681 64 51.068 1.2277 39 31.083 1.0764 14 ill. 158 1.4670 88 70.136 1.3630 63 50.211 1.2212 38 30.286 1.0708 13 10.361 1.4640 87 69.339 1.3579 62 49.414 1.2148 37 29.489 1.0651 12 9.564 1.4600 86 68.542 1.3529' 61 48.617 1.2084 36 28.692 1.0595 11 8.767 1.4570 85 67.745 1.3477 j 60 47.820 1.2019 35 (27.895 1.0540 10 7.970 1.4530 84 66.948 1.34271 59 47.023 1.1958 34 27.098 ' 1.0485 9 7.173 1.4500 83 66.155 1.33761 58 46.226 1.1895 33 26.301 1.0430 8 6.376 1.4460 82 65.354 1.3323 57 45.429 1.1833 32 25.504 1.0375 7 5.579 1.4424 81 64.557 1.3270 56 44.632 1.1770 31 24.707 1.0320 6 4.782 1.4385 80 63.76 1.3216 55 43.835 1.1709 30 23.910 1.0267 5 3.985 1.4346 79 62.963 1.3163 54 43.038 1.1648 29 23.113 1.0212 4 3.188 1.4306 78 62.166 1.3110 53 42.241 1.1587 28 22.316 1.0159 3 2.391 1.4269 77 61.369 1.3056 52 41.444 1.1526 27 21.519 1.0106 2 1.594 1.4228 76 60.572 j 1.3001 51 40.647 i 1.1465 26 20.722 1.0053 1 0.797 The column of dry acid shows the weight which any salifiable base would gain, by uniting 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 rela- tive to the constitution of the dry muriates, to the nitrates, has suggested, that the latter when dry may be considered us consisting, not of a dry nitric acid com- bined with the salinable 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 com- pound of 1 prime of hydrogen, 1 of nitro- gen, and 6 of oxygen.* The strongest acid that Mr. Kirwan could procure at 60 was 1.5543 ; but Rouelle professes to have obtained it of 1.583. Nitric acid should be of the specific gravity of 1.5, or a little more, and colour- less. * That of Mr. Kirwan seems to have consisted of one prime of real acid and one of water, when the suitable correc- tions are made ; but no common chemical use requires it of such a strength. The following table of boiling points has been given by Mr. Dalton. Acidofsp.gr. 1.50 boils at 210 1.45 240 1.42 248 1.40 247 1.35 242 1.30 236 1.20 226 1.15 219 At 1.42 specific gravity it distils unalter- ed. Stronger acid than that becomes weaker, and weaker acid stronger, by boiling. When the strong acid is cooled down to 60 Q , it concretes, 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 stoniach in a concentrated state ; but when greatly- diluted, it may be swallowed without inconvenience. It is often contaminated, through negligence or fraud in the manu- facturer, 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 porcelain tube, it is resolved into oxygen AC1 ACI 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 temperature, a violent detonation ensues, so that this must not be done without great caution. It inflames essential oils, as those of tur- pentine 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 greatly endangered. If it be poured on perfectly dry charcoal powder, it excites combustion, with the emission of copious fumes. By boiling it with sulphur it is decomposed, and its oxygen, uniting with the sulphur, forms sulphuric acid. ^ Chemists in general agree, that it acts very powerfully on almost all the metals ; but Baume has asserted, that it will not dissolve tin, and Dr. Woodhouse of Pennsylvania affirms, that in a highly concentrated and pure state it acts not at all on silver, copper, or tin. though, with the addition of a little water, its action on them is very powerful. * Proust has ascertained, that acid having the specific gravity 1.48, has no more ac- tion on tin than on sand, while acid some- what stronger or weaker acts furiously on the metal. Now, acid of 1.485, by Dr. Ure's table, consists of one prime of real acid united with two of water, constituting, COLOUR. Pale yellow Bright yellow Dark orange Light olive Dark olive Bright green Blue green REAL ACID. 90.5 88.94 8C.84 86.0 85.4 84.8 84.6 it would thus appear, a peculiarly power- ful combination. Acid which takes up T VQ 8 o tns of ' ts weight of marble, freezes, according to Mr. Cavendish, at 2. When it can dis- solve T 5 oVs ** requires to be cooled to 41.6 before congelation; and when so much diluted as to take up only YBiys* it congeals at 40.o. The first has a specific gravity of 1.330 nearly, and con- sists of 1 prime of dry acid -j- 7 of water ; the second has a specific gravity of 1.420, and contains exactly one prime of dry acid 4- four of water ; while the third has a specific gravity of 1.215, consisting of one prime of acid -f- 14 of water. We perceive, that the liquid acid of 1.420, composed of 4 primes of water -f- one of dry acid, possesses the greatest power of resisting the influence of temperature to change its slate. It requires the maximum heat to boil it, when it distils unchanged; and the maximum cold to effect its con- gelation.* It has already been observed, that the nitric acid, when first distilled over, holds in solution a portion of nitric oxide, which is greater in proportion as the heat has been urged toward the end, and much increased by even a small portion of in- flammable matter, should any have been present. The colour of the acid, too, is affected by the quantity of nitric oxide it holds, and Sir H. Davy has given us the following table of proportions answering to its different hues. But these colours are not exact indica- tions 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. The 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 va- rious chemical processes, on account of the facility with which it parts with oxy- gen and dissolves metals ; in medicine as a tonic, and as a substitute for mercurial preparations in syphilis and affections of the liver; as alse in form of vapour to de- stroy contagion. For the purposes of the arts it is commonly used in a diluted state, and contaminated with the sulphuric and muriatic acids, by the name of aquafortis. This is erenerahy prepared by Voi. i. [ 10 ] NITRIC OXIDE, 1.2 2.96 5.56 6.45 7.1 7.76 8. WATER. 8.3 8.10 7.6 7.55 7.5 7.44 7.4 common nitre with an equal weight o*f sulphate of iron, and half its weight of the same sulphate calcined, and distilling the mixture ; or by mixing nitre with twice its weight of dry powdered clay, and dis- tilling in a reverberatory furnace. Two kinds are found in the shops, one called double aquafortis^ 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 regia, and now by that of nitro -muriatic acid, has the property of dissolving gold and platina. On mixing the two acids, heat is given out, an effervescence 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 aqua- ACI ACI fbrtis, and keeping the mixture in a sand- heat till the salt is dissolved ; taking care to avoid the fames as the vessel must be left open ; or by distilling nitric acid with an equal weight, or rather more, of com- mon salt. * On this subject we are indebted to Sir H. Davy for some excellent observa- tions, published by him in the first volume of the Journal of Science. If strong nitrous acid, saturated with nitrous gas, be mixed with a saturated 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 together over mercury, and half a volume of oxygen be added, the immediate con- densation will be more than might be ex- pected 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. It appears then that nitrous acid, and fnuriatic acid gas, have no chemical action on each other. If colourless nitric acid, and muriatic acid of commerce, be mixed to- gether, the mixture immediately becomes yellow, and gains the power of dissolving gold and platinum. If it be gently heated, ptire chlorine arises from it, and the co- lour becomes deeper. If the heat be lon- ger continued, chlorine still rises, but mix- ed with nitrous acid gas' When the pro- cess 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 acid. It appears then from these observations, which have been very often repeated, that nitro-mu- riatic acid owes its peculiar properties to a mutual decomposition 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 imme- diate decomposition, and nitrous acid and muriatic acid are formed. 118 parts of strong liquid nitric acid being decompos- ed in this case, yield 67 of chlorine. Aqua regia does not oxidize gold and platina. It merely causes their combination with chlorine. A bath made of nitro-muriatic acid, di- luted 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 syphilis, a variety of ulcers, and diseases of the skin, chronic hepatitis, bilious dispositions, general de- bility, and languor. He considers every trial as quite inconclusive, where a ptyalism, some affection of the gums, or some very evident constitutional effect, has not arisen from it. The internal use of the same acid has been recommended to be conjoined with 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 barytes directly with nitric acid, or by decomposing the carbonate or sul- phuret of barytes with this acid Exposed to heat it decrepitates, and at length gives out its acid, which is decomposed ; but if the heat be urged too far, the barytes is apt to vitrify with the earth of the cruci- ble. It is soluble in 12 parts of coid, and 3 or 4 of boiling water. It is said to exist in some mineral waters. * It consists of 6.75 acid -f 9.75, or 9.7 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 In- dies, 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 combination of circumstances which tend to compose and condense nitric acid. This acid appears to be produced in all situations, where animal matters are completely decompos- ed, with access of air and of proper sub- stances with which it can readily combine. Grounds frequently trodden by cattle and impregnated with their excrements, or the walls of inhabited 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 attention to the cir- cumstances in which this salt is produced by nature. Dry ditches are dug, and co- vered with sheds, open at the sides, to keep off the rain : these are filled with animal substances such as dung, or other excrements, with the remains of vegeta- bles, and old mortar, or other loose calca- reous earth ; this substance being found to be the best and most convenient recep- tacle for the acid to combine with. Occa- sional watering, and turning up from time to time, are necessary, to accelerate the process, and increase the surfaces to which the air may apply ; but too much moisture is hurtful. W T hen a certain portion of ni- trate is formed, the process appears to go on more quickly ; but a certain quantity stops it altogether, and after this cessation the materials will go on to furnish ACI ACI if what is formed be extracted by lixivia- tion. After a succession of many months, more or less, according to the manage- ment 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 vege- table matter, a considerable portion of the nitrous salt will be common saltpetre, but, if otherwise, the acid will, for the most part, be combined with the calca- reous earth. * It consists of 6.75 acid -f- 5.95 potash.* 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 be- comes of considerable strength. It is then carried to the boiler, and contains nitre and other salts ; the chief of which is com- mon 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. When- ever, 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 remain suspended by virtue of the heat. The common salt thus sepa- rated is taken out with a perforated ladle, and a small quantity of the fluid is cooled, from time to time, that its concentration may be known by the nitre which crystal- lizes in it. When the fluid is sufficiently evaporated, it is taken out and cooled, and great part of the nitre separates in crys- tals ; while the remaining common salt con- tinues dissolved, because equally soluble in cold and in hot water. Subsequent evapora- tion 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 subse- quent 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 con- tained by the nitre, that very little of it will crystallize. For nice purposes, the solution and crystallization of nitre are repeated four times. The crystals of nitre are usually of the form of six-sided flatten- ed prisms, with diedral summits. Its ;aste 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 dis- solve two of nitre, at the temperature of sixty degrees ; but boiling water dissolves its own weight. 100 parts of alcohol, at a heat of 176, dissolve only 2.9. On being exposed to a gentle heat, nitre fuses; and in this state being poured into moulds, so as to form little round cakes, for balls, it is called sal prunella, or crystal mineral. This at least is the way in which this salt is now usually prepared, conforma- bly to the directions of Boerha ve ; though in most dispensatories a twenty-fourth part of sulphur was directed to be defla- grated on the nitre before it was poured out. This salt should not be left on the fire after it has entered into fusion, other- wise it will be converted into a nitrite of potash. If the heat be increased to red- ness, the acid itself is decomposed, and a considerable quantity of tolerably pure oxygen gas is evolved, succeeded by ni- trogen. 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 mor- tar, form the fulminating powder / a small quantity of which, laid on a fire-shovel, and held over the fire till it begins to melt, explodes 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, con- stitute 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 detonate rapidly, and fuse the metal into a globule of sul- phuret, without burning the shell. If nitrate of potash be heated in a retort with half its weight of solid phosphoric or boracic acid, as soon as this acid begins to enter into fusion, it combines with the pot- ash, and the nitric acid is expelled, ac- companied with a small portion of oxygen gas and nitric oxide. Silex, alumina, and barytes, decompose this salt in a high temperature by uniting with its base. The alumina will effect ACI ACI this even after it has been made into pottery. The uses of nitre are various. Beside those already indicated, it enters into the composition of fluxes, and is extensively employed in metallurgy ; it serves to pro- mote the combustion of sulphur in fabri- cating its acid ; it is used in the art of dyeing- ; it is added to common salt for preserving meat, to which it gives a red hue ; it is an ingredient in some frigorific mixtures; and it is prescribed in medi- cine, as cooling, febrifuge, and diuretic ; and some have recommended it ^nixed with vinegar as a very powerful remedy for the sea scurvy. Nitrate of soda, formerly called cubic or quadrangular nitre, approaches in its pro- perties to the nitrate of potash ; but dif- fers from it in being somewhat more solu- ble in cold water, though less in hot, which takes up little more than its own weight ; in being inclined to attract moisture from the atmosphere; and in crystallizing in rhombs, or rhomboidal prisms. It maybe prepared by saturating soda with the ni- tric acid ; by precipitating nitric solutions of the metals, or of the earths, except barytes, by soda ; by lixiviating and crys- tallizing the residuum of common salt dis- tilled with three-fourths its weight of ni- tric acid ; or by saturating the mother waters of nitre with soda instead of potash. This salt has been considered as use- less ; but professor Proust says, that live 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 econo- mical composition for fire-works. *lt con- sists of 6.75 acid-f- 3.95 soda.* Nitrate of strontian maybe 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, however, requiring but four or five parts of water according to Van- quelin, and only an equal weight accord- ing 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 may be useful, perhaps, in the art of pyrotechny. *lt con- sists of 6.75 acid -f- 6.5 strontian.* 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 ob- served when treating of the nitrate of pot- ash. It may also be prepared artificially, by pouring dilute nitric acid on carbonate of lime. 11 the solution be boiled down to \ sirupy consistence, and exposed in a cool place, it crystallizes in long prisms, resembling bundles of needles diverging from a centre. These are soluble, accord- ing to Henry, in an equal weight of boil- ing water, and twice their weight of cold ; soon deliquesce on exposure to the air, and are decomposed to a red heat. Four- croy 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 evaporat- ing the aqueous solution to dryness, con- tinuing the heat till the nitrate fuses, keep- ing it 'in this state five or ten minutes, and then pouring it into an iron pot previous- ly heated, we obtain Saldivin's phvsphonis. This, which is perhaps more properly ni- trite 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 lor drying some of tho 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 property of exploding, and being totally decomposed, at the temperature of 600 ; whence it acquired the name of Jiilrwn fammans. The readiest mode of preparing it is by adding carbonate of ammonia to dilutef nitric acid till saturation takes place. If this solution be evaporated in a heat between 70 and 100, and the evapo- ration 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 crys- tals : if the evaporation be earned so far as for the salt to concrete immediately on a glass rod by cooling, it will form a com- pact mass. According to Sir H. Davy, these differ but little from each other, ex- cept in the water they contain, their com- ponent parts being as follows: Prismatic- con- rG9. ter 12.1 8.2 5.7 Fibrous > tains-5 72.5 < 19.3 Compact 3 acid *74.5 monla Cl9.8 All these are completely deliquescent, but they differ a little in solubility. Alco- hol at 176 dissolves nearly 90.9 of its own weight. * When dried as much as possible with- out decomposition, it consists of 6.75 acid 4- 2.13 ammonia-]- 1.125 water.* The chief use of this salt is for affording nitrous oxide on being decomposed by heat. See NITROGEN, (OXIDE of). Nitrate of magnesia, magnesian nilre, crys- f [ have ascertained, that very strong nitric acid, saturated by carbonate of am- monia, yields the compact nitrate extem- poraneously. ACI AC1 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 fu- sible, 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 hot, so that it is scarcely crystallizable but by spontaneous evaporation. The two preceding species are capable of combining into a triple salt, an ammo- niaco-magnesian nitrate, either by uniting the two in solution, or by a partial decom- position 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, ni- trous oxide, and nitric acid. The residuum is pure magnesia. It is disposed to attract moisture from the air, but is much less de- liquescent 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 1 . It consists of 78 parts of ni- traie of magnesia, and 22 of nitrate of am- monia. 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 duc- tile 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 so- luble and very deliquescent. Nitra'e, or rather supernitrate, of alu- mina crystallizes, though with difficulty, in thin, soft, pliable flakes. It is of an aus- tere and acid taste, and reddens blue veg- etable colours. It may be formed by dis- solving in diluted nitric acid, with the as- sistance of heat, fresh precipitated alumi- na, well washed but not dried. It is deli- quescent, and soluble in a very small por- tion 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 decom- posed by fire, very soluble in water, and deliquescent. It may be prepared by dis- solving zircone in strong nitric acid ; but, like the preceding species, the acid is al- ways 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. ACID (NiTuors). It was formerly called fuming nitrous acid. It appears to form a distinct genus of salts, that may be termed nitrites. But these cannot be made by a direct union of their component parts, be- ing obtainable only by exposing a nitrate to a high temperature, which expels a por- tion of its oxygen in the state of gas, and leaves the remainder in the state of a ni- trite, if the heat be not urged so far, or continued so long, as to effect a complete decomposition of the salt. In this way the nitrites of potash and soda may be obtain- ed, and perhaps those of barytes, strontian, lime, and magnesia. The nitrites are par- ticularly characterized, by being decom- posable by all the acids except the car- bonic, even by the nitric acid itself, all of which expel from them nitrous acid. We are little acquainted with any one except that of potash, which attracts moisture from the air, changes blue vegetable colours to green, is somewhat acrid to the taste, and when powdered, emits a smell of nitric oxide. * The acid itself is best obtained by ex- posing nitrate of lead to heat in a glass re- tort. Pure nitrous acid comes over in the form of an orange coloured liquid. It is so 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 ef- fervescence. It is composed of one volume of oxygen united with two of nitrous gas. It therefore consists by weight of 1.75 ni- trogen -f- 4 oxygen ; by measure of 1| oxygen -f- 1 nitrogen. The various co- loured 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 (NITRIC OXYGENIZED). In out- general remarks on acidity, we have de- scribed Mr. Thenard's newly discovered method of oxygenizing the liquid acids. The first that he examined was the com- bination of nitric acid and oxygen. When the peroxide of barium, prepared by satu- rating 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 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 precipitate of sulphate of barytes falls, and the filtered ACI AC1 liquor is merely water, holding in solution oxygenized nitric acid. This acid is liquid and colourless ; it strongly reddens turn- sole, and resembles in all its properties nitric acid. When heated it immediately begins to discharge oxygen ; but its decomposition is never complete unless it be kept boiling for some time. The only method which M. Thenard found successful for concen- trating it, was to place it in a capsule, under the receiver of an air pump, along with another capsule full of lime, and to exhaust the receiver. By this means he obtained an acid sufficiently concentrated to give out 11 times its bulk of oxygen gas. This acid combines very well with ba- rytes, potash, soda, ammonia, and neu- tralizes them. When crystallization com- mences in the liquid, by even a sponta- neous evaporation, these salts are instant- ly decomposed. The exhausted receiver 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 common acid acts on, and when it is not too concentrated, it dissolves them without effervescence. Deutoxide, or peroxide of barium, contains just double the proportion of oxygen that its protoxide 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 deposite. It is insoluble in ammonia, and accord- ing to all appearance, is a protoxide of silver. As soon as we plunge a tube containing oxide of silver into a solution of oxygen- ized nitrate of potash, a violent efferves- cence takes place, the oxide is reduced, the silver precipitates, 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 unac- countable phenomenon is the following : If silver, in a state of extreme division (fine filings), be put into the oxygenized nitrate, or oxygenized muriate of potash, the whole oxygen is immediately disen- gaged. 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 oxygen- ized 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 employ- ed in the state of filings. Gold scarcely acts. The peroxides of manganese and of lead decompose the 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 alteration. Though nitric acid itself has no action on the peroxides of lead and manganese, the oxygenized acid dissolves both of them with the greatest facility. The so- lution is accompanied by a great disen- gagement of oxygen gas. The effect of silver, he thinks, may probably be ascri- bed to voltaic electricity. The remarks appended to our account of M. Thenard's oxygenized muriatic acid, are equally applicable to the nitric ; but the phenomena are too curious to be omitted in a work of the present kind.* * Acin (OtEic). 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, combined with the potash. When the alkali is separated by tartaric acid, the oily principle of fat is obtained, which M. Chevreul purifies by saponify- ing 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 26.00 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 satu* AM ACI rate 16.58 of potash, 10.11 of soda, 7.52 of magnesia, 14.83 of zinc, and 13.93 perox- ide of copper. M. Chevreul's experi- ments 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, which a- bounds in wood sorrel, and which, com- bined with a small portion of potash, as it exists in that plant, has been sold under the name of salt of lemons, to be used as a substitute for the juice of that fruit, par- ticularly for discharging ink spots and iron-moulds, was long supposed to be analogous in that of tartar. In the year 1776, however, Bergmann discovered, that a powerful acid might be extracted from sugar by means of the nitric ; and a few years afterwards Scheele found this to be identical with the acid existing naturally in sorrel. Hence the acid began to be distinguished by the name of saccharine, but has since been known in the new nomenclature by that of oxalic. Scheele extracted this acid from the salt of sorrel, or acidulous oxalate of pot- ash, as it exists in the juice of that plant, by saturating it with ammonia, when it becomes a very soluble triple salt, and adding to the solution nitrate of barytes dissolved in water. Having well washed the oxalate of barytes, which is precipita- ted, he dissolved it in boiling water, and precipitated its base by sulphuric acid. To ascertain that no sulphuric acid re- mained in the supernatant liquor, he added a little of a boiling solution of oxalate of barytes till no precipitate took place, and then filtered the liquor, which contained nothing but pure oxalic acid, which he crystallized by evaporation and cooling. It may be obtained, however, much more readily and economically from sugar in the following way : To six ounces of nitric acid in a stoppered retort, to which a large receiver is luted, add, by degrees, one ounce of lump sugar coarsely pow- dered. 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 sirupy consistence, and this will form regular crystals, amounting to 58 parts from 100 of sugar. These crys- tals must be dissolved in water, re-crystal- lized, and dried on blotting paper. A variety of other substances afford the oxalic acid when treated by distillation with the nitric. Bergmann procured it from honey, gum arabic, alcohol, and the calculous concretions in the kidneys and bladders of animals. Scheele and Hermb- stadt 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, Goetling from beech wood. Kohl from the residuum in the distillation of ar- dent spirits. Westrumb not only from the crystallized acids of currants, cherries, ci- trons, raspberries, but also from the sac- charine matter of these fruits, and from the uncrvstallizable parts of the acid jui- ces. Hoffmann from the juice of the bar- berry ; and Berthollet from silk, hair, ten- dons, wool ; also from other animal sub- stances, especially from the coagulum of blood, whites of eggs, and likewise from the amylaceous and glutinous parts of flour. M. Berthollet observes, that the quantity of the oxalic acid obtained by treating wool with nitric acid was veiy considerable, being aV ove half the weight of the wool employed. He mentions a difference which he observed between animal and vegetable substances thus treat- ed with nitric acid, namely, that the for- mer yielded, beside ammonia, a large quan- tity 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 r and he remarks, that in this instance the glutinous part of flour resembled animal substances, whereas the amylaceous part of the flour retained its vegetable properties. He further remarks, that the quantity of oxalic acid furnished by vegetable matters thus treated is pro- portionable 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 li- quor, which, on examination, proved to be an aqueous solution of pure oxalic acid. Proust and other chemists had before ob- served, that the shoes of persons walking through a field of chick pease were corro- ded. Oxalic acid crystallizes in quadrilateral prisms, the sides of which are alternately broad and narrow, and summits diedral ; or, if crystallized rapidly, in small irregu- lar needles. They are efflorescent in dry air, but attract a little humidity if it be damp ; are soluble in one part of hot and two of cold water; and are decomposable by a red heat, leaving a small quantity of coaly residuum. 100 parts of alcohol take up near 56 at a boiling heat, but not above 40 cold. Their acidity is so great, that when dissolved in 3600 times their weight of water, the solution reddens litmus pa- per, and is perceptibly acid to the taste. The oxalic acid is a good test for de- tecting lime, which it separates from all the other acids, unless they are present in excess. It has likewise a greater affinity ACI ACI for lime than for any other of the bases, and forms with it a pulverulent insoluble salt, not decomposable except by fire, and turning sirup of violets green. * From the oxalate of lead, Berzelius infers its prime equivalent to be 4.552, and by igneous decomposition he finds it re- solved into 66.534 oxygen, 33.222 carbon, and 0.244 hydrogen. The quantity of the latter, when reduced to primitive ratios, gives only, as Dr. Thomson admits, l-12th of an atom of hydrogen, which makes this analysis of Berzelius and the Atomic theory incompatible. Since Berzeljjis pub- lished his analysis, oxalic acid has been made the subject of some ingenious re- marks by Dobereiner, in the 16th vol. of Schvveigger's Journal. We see that the carbon and oxygen are to each other in the simple ratio of 1 to 2 ; or referred to their prime equivalent, as 2 of carbon = 1.5, to 3 of oxygen = 3. This propor- tion is what would result from a prime of carbonic acid = C -\- 2. O, combined with one of carbonic oxide = C -f- O. C being carbon, and O oxygen. The sum of the above weights gives 4.5 for the prime equivalent of oxalic acid, disregarding hy- drogen, which constitutes but l-37th of the whole, and may possibly be referred to the imperfect desiccation of the oxala'e of lead subjected to analysis. Oxalic acid acts as a violent poison when swallowed in the quantity of 2 or 3 drachms; and several fatal accidents have lately occur- red in London, in consequence of its being improperly sold instead of Epsom salts. Its vulgar name of salts, under which the acid is bought for the purpose of whiten- ing boot-tops, occasions these lamentable mistakes. But the powerfully acid taste of the latter substance, joined to its prismatic or needle-formed crystallization, are suffi- cient to distinguish it from every thing else. The immediate rejection from the stomach of this acid, by an emetic, aided by copious draughts of warm water con- taining bicarbonate of potash, or soda, chalk, or carbonate of magnesia, are the proper remedies.* With barytes it forms an insoluble salt; but this salt will dissolve in water acidu- lated with oxalic acid, and afford angular crystals. If, however, we attempt to dis- solve these crystals in boiling water, the excess of acid will unite with the water, and leave the oxalate, which will be pre- cipitated. The oxalate of strontian too is a nearly insoluble compound. Oxalate of magnesia too is insoluble, un- less the acid be in excess. The oxalate of potash exists in two states, that of a neutral salt, and that of an acidule. The latter is generally obtained ii;om the juice of the leaves of the oxutis acetosella, wood sorrel, or nnncx acetosa^, common sorrel. The expressed juice, be- ing diluted with water, should be set by for a few days, till the feculent parts havt subsided, and the supernatant fluid is be- come clear; or it may be clarified, when expressed, with the whites of eggs. It is then to be strained off, evaporated to a pellicle, and set in a cool place to crystal- lize. The first product of crystals being taken out, the liquor may be further evap- orated, and crystallized ; and the same, process repeated till no more can be ob- tained. In this way Schlereth informs us about nine drachms of crystals may be ob- tained from two pounds of juice, which are generally afforded by ten pounds of wood sorrel. Savary, however, says, that ten parts of wood sorrel in full vegetation yield five parts of juice, which give little more than a two-hundredth of tolerably pure salt. He boiled down the juice, how- ever, in the first instance, without clari- fying it; and was obliged repeatedly to dissolve and re-crystallize the salt to ob- tain it white. This salt is in small, white, neeclly, or lamellar crystals, not alterable in the air. It unites with barytes, magnesia, soda, am- monia, and most of the metallic oxides, in- to triple salts. Yet its solution precipitates the. nitric solutions of mercury and silver in the state of insoluble oxalate of these metals, the nitric acid in this case com- bining with the potash. It attacks iron, lead, tin, zinc, and antimony. This salt, besides its use in taking out ink spots, and as a test of lime, forms with sugar and water a pleasant cooling bever- age ; and according to Berthollet, it pos- sesses considerable powers as an antisep- tic. The neutral oxalate of potash is very soluble, and assumes a gelatinous form, but may be brought to crystallize in hex- aedral prisms with diedral summits, by ad- ding more potash to the liquor than is suf- ficient to saturate the acid. Oxalate of soda likewise exists in two different states, those of an acidulous and a neutral salt, which in their properties are analogous to those of potash. The acidulous oxalate of ammonia is crystallizable, not very soluble, and capa- ble, like the preceding acidules, of com- bining with other bases, so as to form triple salts. But if the acid be saturated with ammonia, we obtain a neutral oxalate, which on evaporation yields very fine crystal* in tetraedral prisms with diedral summits, one of the planes of which cuts of!' three sides of the prism. This salt is decomposable by fire, which raises frr.m it carbonate of ammonia, and leaves only some light traces of a coaly residuum. Lime, barytes, and strontiun unite \vilh ACI ACI Its acid, and the ammonia flies off' in the form of gas. The oxalic acid readily dissolves alumi- na, and the solution gives on evaporation a yellowish transparent mass, sweet and a little astringent to the taste, deliquescent, and reddening tincture of litmus, but not sirup of violets. This salt swells up in the fire, loses its acid, and leaves the alumina a little coloured. * The composition of the different oxa- lates may be ascertained by considering the neutral salts as consisting of one prime of acid = 4.552 to 1 of base, and the bin- oxalate of potash of 2 of acid to 1 of base, as was first proved by Ur. Wollaston. But this eminent philosopher has further shown, that oxalic acid is capable of com- bining in four proportions with the oxides, whence result neutral oxalates, suboxa- lates, acidulous oxalates, and acid oxalates. The neutral contain twice as much acid as the suboxalates; one-half of the quantity of acid in the acidulous oxalates ; and one- quarter of that in the acid oxalates.* Acin (PERLATE). This name was given by Bergmann to the acidulous phosphate of soda, Haupt having called the phosphate of soda sal mirabile perlatum. Acin (PHOSPHORIC.) The base of this acid, or the acid itself, abounds in the mi- neral, vegetable, and animal kingdoms. In the mineral kingdom it is found in combi- nation with lead, in the green lead ore ; with iron, in the bog ores which afford oold short iron ; and more especially with calcareous earth in several kinds of stone. Whole mountains in the province of Es- tremadura in Spain are composed of this combination of phosphoric acid and lime. Mr. Howies affirms, that the stone is whi- tish and tasteless, and affords a blue flame without smell when thrown upon burning coals. Mr. Proust describes it as a dense stone, not hard enough to strike fire with steel ; and says that it is found in strata, which always lie horizontally upon quartz, and which 'are intersected with veins of quartz. When this stone is scattered up- on burning coals, it does not decrepitate, but burns with a beautiful green light, which lasts a considerable time. It melts into a white enamel by the blow-pipe ; is soluble with heat, and some effervescence in the nitric acid, and forms sulphate of lime with the sulphuric acid, while the phosphoric acid is set at liberty in the fluid. The vegetable kingdom abounds with phosphorus, or its acid. It is principally found in plants that grow in marshy places, in turf, and several species of the white woods. Various seeds, potatoes, agaric, soot, and charcoal afford phosphoric acid, To this Prof. Bartholdi ascribes two accidents at the powder-mills at Essone, where spontaneous combustion appeured Vat, i [11]. by abstracting the nitric acid from thetfi> and lixiviating the residue. The lixivium contains the phosphoric acid, which may either be saturated with lime by the addi- tion of lime-water, in which case it forms a solid compound; or it may be tried by examination of its leading properties by other chemical methods. In the animal kingdom it is found in al- most every part of the bodies of animals which are not considerably volatile. There is not, in all probability, any part of these organized beings which is free from it. It has been obtained from blood, flesh, both of land and water animals ; from cheese ; and it exists in large quantities in bones, combined with calcareous earth. Urine contains it, not only in a disengaged state, but also combined with ammonia, soda, and lime. It was by the evaporation, and distillation of this excrementitious fluid with charcoal that phosphorus was first made ; the charcoal decomposing the dis- engaged acid and the ammoniacal salt. (See PHOSPHORUS.) But it is more cheaply ob- tained by the process of Scheele, from bones, by the application of an acid t their earthy residue after calcination. In this process the sulphuric acid ap- pears to be the most convenient, because it forms a nearly insoluble compound with the lime of the bones. Bones of beef, mutton, or veal, being- calcined to white- ness in an open fire, lose almost half of their weight. This must be pounded, and sifted, or the trouble may be spared by buying the powder that is sold to make cupels for the assayers, and is, in fact, the powder of burned bones ready sifted. To three pounds of the powder there may be added about two pounds of concentrated sulphuric acid. Four or five pounds of water must be afterward added to assist the action of the acid ; and during the whole process the operator must remem- ber to place himself and his vessels so that the fumes may be blown from him. The whole may then be left on a gentle sand bath for twelve hours or more, taking care to supply the loss of water which happens by evaporation. The next day a large quantity of water must be added, the whole strained through a sieve, and the residual matter, which is sulphate of lime, must be edulcorated by repeated affusion* of hot water, till it passes tasteless. The waters contain phosphoric acid nearly free from lime, and by evaporation, first in glazed earthen, and then in glass vessels, to have taken place in one instance in the charcoal store-room, in the other in the box into which the charcoal was sifted; as well as three successive explosions at the powder-mills of Vosges. This cer* tainly merits the attention of gunpowder manufacturers, ACI ACI or rather in vessels of platina or silver, for the hot acid acts upon glass, afford the acid in a concentrated state, which, by the force of a strong heat in a crucible, may be made to acquire the form of a transpa- rent consistent glass, though indeed it is usually of a milky, opaque appearance. For making phosphorus, it is not neces- sary to evaporate the water further than to bring it to the consistence of sirup ; and the small portion of lime it contains is not an impediment worth the trouble of removing, as it affects the produce very little. But when the acid is required in a purer state, it is proper to add a quantity of carbonate of ammonia, which, by dou- ble elective attraction, precipitates the lime that was held in solution by the phos- phoric acid. The fluid being then evapo- rated, affords a crystallized ammoniacal salt, which may be melted in a silver ves- sel, as the acid acts upon glass or earthen vessels. The ammonia is driven off by the heat, and the acid acquires the form of a compact glass as transparent as rock crystal, acid to the taste, soluble in water, and deliquescent in the air. This acid is commonly pure, but never- theless may contain a small quantity of so- da, originally existing in the bones, and not capable of being taken away by this process, ingenious as it is. The only une- quivocal method of obtaining a pure acid appears to consist in first converting it in- to phosphorus by distillation of the mate- rials with charcoal, and then converting it again into acid by rapid combustion, at a high temperature, either in oxygen or at- mospheric air, or some other equivalent process. Phosphorus may also be converted into the acid state by treating it with nitric acid. In this operation, a tubulated retort with a ground stopper, must be half filled with nitric acid, and a gentle heat applied. A small piece of phosphorus being then introduced through the tube will be dis- solved with effervescence, produced by the escape of a large quantity of nitric ox- ide. The addition of phosphorus must be continued until the last piece remains undissolved. The fire being then raised to drive over the remainder of the nitric acid, the phosphoric acid will be found in the retort, partly in the concrete and part- ly in the liquid form. Sulphuric acid produces nearly the same effect as the nitric; a large quantity of sulphurous acid flying off. But as it re- quires a stronger heat to drive off the last portions of this acid, it is not so well adapt- ed to the purpose. The liquid chlorine likewise acidifies it. When phosphorus is burned by a strong heat, sufficient to cause it to flame rapid- ly,' it is almost perfectly converted into dry acid, some of which is thrown up by the force of the combustion, and the rest remains upon the supporter. This substance has also been acidified by the direct application of oxygen gas passed through hot water, in which the phosphorus was liquefied or fused. The general characters of phosphoric acid are : 1. It is soluble in water in all proportions, producing a specific gravity, which increases as the quantity of acid is greater, but does not exceed 2.687, which is that of the glacial acid. 2. It produces heat when mixed with water, though not very considerable. 3. It has no smell when pure, and its taste is sour, but not corrosive. 4. When perfectly dry, it sub- limes in close vessels; but loses this pro- perty by the addition of water ; in which circumstance it greatly differs from the boracic acid, which is fixed when dry, but rises by the help of water. 5. When con- siderably diluted with water, and evapo- rated, the aqueous vapour carries up a small portion of the acid. 6. With char- coal or inflammable matter, in a strong heat, it loses its oxygen, and becomes con- verted into phosphorus. Phosphoric acid is difficult of crystalli- zing. Though the phosphoric acid is scarcely corrosive, yet, when concentrated, it acts upon oils, which it discolours, and at length blackens, producing heat, and a strong smell like that of ether and oil of turpen- tine ; but does not form a true acid soap. It has most effect on essential oils, less on drying oils, and least of all on fat oils. Spirit of wine and phosphoric acid have a weak action on each other. Some heat is excited by this mixture, and the product which comes over in distillation of the mix- ture is strongly acid, of a pungent arsenical smell, inflammable with smoke, miscibie in all proportions with water, precipitating silver and mercury from their solutions, but not gold; and although not an ether, yet it seems to be an approximation to that kind of combination. * From the syntheses of the phosphates of soda, barytes, and lead, Berzelius de- duces the prime equivalent of phosphoric acid to be 4.5. But the experiments of Berzelius on the synthesis of the acid it- self, show it to be a compound of about 100 phosphorus -f- 133 oxygen ; or of 2 oxygen -f- 1.5 phosphorus == 3.5 for the prime equivalent of the acid. Lavoisier's synthesis gave-2 oxygen -j- 1.33 phospho- rus. So did that of Sir H. Davy by rapid combustion in oxygen gas, as published in the Phil. Trans, for 1812. Dr. Thomson, in his account of the improvements in Phy- sical Science, published in his Annals for January 1817, says, "it is quite clear from these analyses (of Berzelius) that the ACI ACI equivalent number for phosphoric acid is 4.5." M. Dulong 1 , in an elaborate paper published in the third volume of the Me- moires d'Arcneil, gives as the result of di- versified experiments, the proportions of 100 phosphorus to 123 oxygen ; or of 2 oxygen -f- 1.627 phosphorus = 3.627 for the acid equivalent. In the Annals of Philosophy for April 1816, page 305, Dr. Thomson gives the following statement : " From this result it follows that the acid is composed of Phosphorus, 100 Oxygen, 123,46. " To verify this result, the author (Dr. Thomson) had recourse to the phosphate of lead, which is a compound of 2 atoms phosphoric acid-f 1 atom yellow oxide of lead." He gives three analyses of this sal* ; one by Dr Wollaston ; one by Pro- fessor Berzelius; and one by himself. These analyses are as follow : Acid. Base. By Wollaston, 100 -f 370.72 Berzelius, 100 -f- 380.56 Thomson, 100 -f- 398.49 Mean, 100 + 383.26. This mean, which corresponds nearly with the analysis of Berzelius, is consid- ered by him as exhibiting the true com- position of phosphate of lead From this the weight of an atom of phosphoric acid is shown to be 3.649. But after a com- parison of results by different methods, he says, " This gives us 1.634 for the weight of an atom of phosphorus ; 2.634 for the weight of an atom of phosphorous acid ; and 3.634 for the weight of an atom of phosphoric acid." Page 306. In the subsequent January, when he^ gives an Account of Physical Science for the same year 1816, however, he says, "It is quite clear from these analyses," (of Berzelius, whom he there properly styles one of the most accurate chemists of the present day), " that the equivalent num- ber for phosphoric acid is 4.5." And far- ther, in the fifth edition of his System of Chemistry, published in 1817, from an ex- tremely large collection of experiments, he determines the equivalent of phospho- rus to be 1.5; and that of phosphoric acid to be 4.5. Finally, in March 1820, without hinting in the least at his abandonment of the number 3.634, and adoption of 4.5, he merely says, " that a set of experiments lie published some years ago seem to me to demonstrate the constitution of these two acids in a satisfactory manner." And he immediately fixes on 3.5 for phosphoric acid. Amid all these perplexities, it is com- fortable to resort to Sir H. Davy's clear and decisive paper, read before the Royal Society on the 9th April 1818. With his well known sagacity, he invented a new method of research, to elude the former sources of error. He burned the vapour of phosphorus as it issues from a small tube, contained in a reton filled with oxy- gen gas. By adopting this proces, he de- termined the composition of phosphoric acid to be 100 phosphorus -f- 134.5 oxy- gen ; whence its equivalent comes out 3.500. Phosphorous acid he then shows to consist of 1 oxygen -f ' -500 phosphorus = 2.500. We shall therefore fix on Sir H. Davy's number 3.500 for the prime equivalent of phosphoric acid. We see, indeed, in the Annals of Philos, for 1816, in a paper on phosphuretted hy- drogen by Dr. Thomson, that this chemist had determined the atom of phosphorus to be 1.5, and that of phosphoric acid 3.5, but he subsequently renounced them. It will be instructive to place his fluctuations of opinion in one view. In the Annals for April 1816, the report of Dr. Thomson's paper, read at the Royal Society, on phosphoric acid and the phos* phates, makes the acid equivalent 3.634; in the Annals for August 181 6, the phos- phuretted hydrogen experiments make it 3.5: the history of 1816 improvements, inserted in January 1817, gives us 4.5 as the equivalent, and an explicit renuncia- tion of 3.5 ; the System of Chemistry in October 1817, confirms this number 4.5 by multiplied facts and reasonings ; and, finally, after Sir H. Davy's experiments appeared in 1818, which demonstrated 3.500 to be the real number, Dr. Thomson resumes 3.5; and to show his claim to pri- ority, refers simply to his former paper on phosphuretted hydrogen. From this ex- ample, beginners in the study of chemistry will learn the danger of dogmatizing has- tily on experimental subjects.* * ACID (PHOSPHOROUS) was discovered in 1812 by Sir H. Davy. When phospho- rus and corrosive sublimate act on each other at an elevated temperature, a liquid called protochloride of phosphorus is form- ed. Water added to this, resolves it into muriatic and phosphorous acids. A mo- derate heat suffices to expel the former, and the latter remains, associated with water. It has a very sour taste, reddens vegetable blues, and neutralizes bases. When heated strongly in open vessels, it inflames. Phosphuretted hydrogen flies off, and phosphoric acid remains. Ten parts of it heated in close vessels give off 1^ of bihydroguret of phosphorus, and leave 8 of phosphoric acid. Hence the liquid acid consists of 80.7 acid -f- 19.3 water. Its prime equivalent is 2.5.* * ACID (HYPOPHOSPHOHOUS), lately dis- covered by M. Dulong. Pour water on the phosphuret of barytes, and wait till all the phosphuretted hydrogen be disengag. AOI ACI ed. Add cautiously to the filtered liquid dilute sulphuric acid, till the barytes be all precipitated in the state of sulphate. The supernatant liquid is hypophosphorous acid, which should be passed through a iilter. This liquid may be concentrated by evaporation, till it become viscid. It has a very sour taste, reddens vegetable blues, and does not crystallize. It is pro- bably composed of 2 primes of phospho- rus = 3. -f- 1 of oxygen. Dulong's analy- sis approaches to this proportion. He assigns, but from rather precarious data, 100 phosphorus to 37.44 oxygen.* The hypophosphites have the remarkable pro- perty of being all soluble in water; while many of the phosphates and phosphites are insoluble. M. Thenard succeeded in oxygenizing phosphoric acid by the method described under nitric and muriatic acids. With regard to the phosphates and phosphites, we have so many discrepan- cies in our latest publications, that we must suspend our judgment as to their composition. Sir H. Davy says most ap- propriately in his last memoir on some of the combinations of phosphorus, that "new researches are required to explain the anomalies presented by the phosphates." We may add, that after he has so effectu- ally cleared up the mysteries of the acids themselves, the scientific world look to him to throw the same light on their saline combinations.* Phosphoric acid, united with barytes, produces an insoluble salt, in the form of a heavy white powder, fusible at a high temperature into a gray enamel. The best mode of preparing it is by adding an alka- line phosphate to the nitrate or muriate ofbarytes. The phosphate of strontian differs from the preceding in being soluble in an ex- cess of its acid. Phosphate of lime is very abundant in the native state. At Marmarosch in Hun- gary, it is found in a pulverulent form, mixed with fluate of lime : in the province of Estremadura in Spain, it is in such large masses, that walls of enclosures, and even houses, are built with it; and it is frequent- ly crystallized, as in the apatite of Werner, when it assumes different tints of gray, brown, purple, blue, olive, and green. In the latter state, it has been confounded with the crysolite, and sometimes with the beryl and aqua marine, as in the stone called the Saxon beryl. It likewise con- stitutes the chief part of the bones of all animals. The phosphate of lime is very difficult to fuse, but in a glasshouse furnace it soft- ens, and acquires the semitransparency and grain of porcelain. It is insoluble in , 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 phosphate 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 per- ceptibly acid taste. It may be prepared by partially decomposing the calcareous phos- phate of bones by the sulphuric, nitric, or muriatic acid, or by dissolving that phos- phate in phosphoric acid. It is soluble ia water, and crystallizable. Exposed to the action of heat, it softens, liquefies, swells up, becomes dry, and may be fused into a transparent glass, which is insipid, insolu- ble, 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. The phosphate of potash is very deli- quescent, and not crystallizable, but con- densing into a kind of jelly. Like the pre- cediivg species, it first undergoes the aque- ous fusion, swells, dries, and may be fused into a glass ; but this glass deliquesces. It has a sweetish saline taste. The phosphate of soda was first disco- vered combined with ammonia in urine, by Schockwitz, and was called fusible or micro- cosmic salt. Margraff obtained it alone by lixiviating the residuum left after prepar- ing phosphorus from this triple salt and charcoal. Haupt, who first discriminated the two, gave the phosphate of soda the name of sal mirabileperlatwn. Ron elle very properly announced it to be a compound of soda and phosphoric acid. Bergman considered it, or rather the acidulous phos- phate, as a peculiar acid, and gave it the name ofperlate acid. Guyton-Morveau did the same, but distinguished it by the name ofouretic: at length Klaproth ascertained its real nature to be as Rouelle had affirmed. This phosphate is now commonly pre- pared by adding to the acidulous phos- phate 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 evaporated 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 regular. M. Funcke, of Linz, recommends, as a more economical and expeditious mode, to saturate the excess of lime in calcined bones by dilute sulphu- ric acid, and dissolve the phosphate of ACI ACI lime tli.it remains in nitric acid. To this solution he adds an equal quantity of sul- Shate of soda, and recovers the nitric acid y distillation. He then separates the phosphate of soda from the sulphate of lime by elutriation and crystallization, as usual. The crystals are rhomhoidal prisms of different shapes; efflorescent; soluble in 3 parts of cold and 14 of hot water. They are capable of being- fused into an opaque white glass, which may be again dissolved and crystallized. It may be con- verted into an acidulous phosphate by an addition of acid, or by either of the strong- acids, which partially, but not wholly, de- compose it. As its taste is simply saline, without any thing- disagreeable, it is much used as a purg-ative, chiefly in broth, in which it is not distinguishable from com- mon salt. For this elegant addition to our pharmaceutical preparations, we are in- debted to Dr. Pearson. In assays with the blow-pipe it is of great utility ; and it has been used instead of borax for soldering. The phosphate of ammonia crystallizes in prisms with four regular sides, termi- nating in pyramids, and sometimes in bun- dles of small needles. Its taste is cool, sa- line, 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 lit- tle more soluble in hot water than in cold, \vhich takes up a fourth of its weight. It is pretty abundant in human urine, par- ticularly after it is become putrid. It is an excellent flux both for assay sand the blow- pipe, and in the fabrication of coloured glass and artificial gems. Phosphate of magnesia crystallizes in ir- regular hexaedral prisms, obliquely trun- cated ; 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 prepar- ing it is by mixing equal parts of the solu- tions of phosphate of soda and sulphate of magnesia, and leaving them some time at rest, when the phosphate of magnesia will crystallize, 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 Bar- tholdi, and likewise by the former in some human urinary calculi. Notwithstanding the solubility of the phosphate of ammo- nia, this triple salt is far less soluble than the phosphate of magnesia. It is partially decomposable into phosphorus by char- coal, in consequence of its ammonia. The phosphate of g-lucine has been ex amined by Vauquelin, who informs us, that it is a white powder, or mucilaginous mass, without any perceptible taste ; fusible, but not decomposable by heat ; unaltera- ble in the air; and insoluble unless in an excess of its acid. It has been observed, that the phospho- ric acid, aided by heat, acts upon silex; and we may add, that it enters into many artificial gems in the state of a siliceous phosphate. ACID (Purssrc). The combination of this acid with iron was long- known and used as a pigment by the name of prussian blue, before its nature was understood. Macquer first found, that alkalis would de- compose prussian blue, by separating- the iron from the principle, with which it was combined in it, and which he supposed to be phlogiston. In consequence, the prus- siate of potash was long qalled phlogisti- cated alkali. Bergmann, however, from a more scientific consideration of its proper- ties, ranked it among the acids ; and as early as 1772, Sage announced, that this animal acid, as he called it, formed with the alkalis neutral salts, that with potash forming octa'' ; dral crystals, and that with soda, rhomboids or hexagonal laminae. About ttie same time Scheele instituted a series of sagacious experiments, not only to obtain the acid separate, which he ef- fected, but also to ascertain its constituent principles. These, according to him, are ammonia and carbon ; and Berthollet there- after added, that its triple base consists of hydrogen and azote, nearly, if not precise- ly, in the proportions that form ammonia, and carbon. Berthollet could find no oxy- gen in any of his experiments for decom- posing this acid. Scheele's method is this : Mix four oun- ces of prussian blue with two of red oxide of mercury prepared by nitric acid, and boil them in twelve ounces by weight of water, till the whole becomes colourless ; filter the liquor, and add to it one ounce of clean iron filings, and six or seven drams of sulphuric acid. Draw off' by distillation about a fourth of the liquor, which will be prussic acid ; though, as it is liable to be contaminated with a portion of sulphuric, to render it pure, it may be rectified by redistilling it from carbonate of lime. This prussic acid has a strong smell of peach blossoms, or bitter almonds ; its taste is at first sweetish, then acrid, hot, and virulent, and excites coughing ; it has a strong tendency to assume the form of gas ; it has been decomposed in a high temperature, and by the contact of light, into carbonic acid, ammonia, and carbu- retted hydrogen. It does not completely neutralize alkalis, and is displaced even by the carbonic acid ; it has no action upon ACI ACI metals, but unites with their oxides, and forms salts for the most part insoluble; it likewise unites into triple salts with these oxides and alkalis ; the oxygenated muri- atic acid decomposes it. The peculiar smell of the prussic acid could scarcely fail to suggest its affinity with the deleterious principle that rises in the distillation of the leaves of the lauro- cerasus, bitter kernels of fruits, and some other vegetable productions; and M. Schrader of Berlin has ascertained the fact, that these vegetable substances do con- tain a principle capable of formingpa blue precipitate with iron; and that with lime they afford a test of the presence of iron, equal to the prussiate of that earth. Dr. Bucholz of Weimar, and Mr. Roloff of Magdeburg, confirm this fact. The prussic acid appears to come over in the distilled oil. * Prussic acid and its combinations have been lately investigated by M, Gay-Lussac and Vauquelin in France, and Mr. Porrett in England, who have happily succeeded in removing in some measure the veil which continued to hang over this depart- ment of chemistry. To a quantity of powdered prussian blue diffused in boiling water, let red oxide of mercury be added in successive portions till the 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 crystals, muri- atic acid, in rather less quantity than is sufficient to saturate the oxide of mercurv, which formed them. Apply a very gentle heat to the retort. Prussic acid, named hydrocyanic by M. Gay-Lussac, will be evolved in vapour, and will condense in the tube. Whatever muriatic acid may pass over with it, will be abstracted by the marble, while the water will be absorbed tythe muriate of lime. By means of a rnoderate heat applied to the tube, the prussic acid may be made to pass succes- sively along; and after being left some time in contract with the muriate of lime, it may be finally driven into the receiver. As the carbonic 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, possessing a strong odour ; "and the exhalation, if incautiously snuffed up the nostrils, may produce sickness or tainting. Its taste is cooling at first, then hot, as- thenicin a high degree, and a true poison. Its specific gravity at 44, is 0.7058 ; at 64 it is 0.6969. It boils at 8l, and con- geals at, about 3. It then crystallizes 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 produced by putting a small drop at the end of a slip of paper or a glass tube. Though repeatedly recti- fied on pounded marble, it retains the property of feebly reddening paper tinged blue with litmus. The red colour disap- pears as the acid evaporates. The specific gravity of its vapour, ex- perimentally compared to thac of air, is 0.9476. By calculation from its constitu- ents, its true specific gravity comes out 0.9360, which differs from the preceding number by only one-hundredth part. This small density of prussic acid, com- pared with its great volatility, furnishes a new proof that the density of vapours 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 of86 y into ajar, 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 mixture 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 without any chance that the prussic acid will condense, provided the temperature be not too low ; but during M. Gay-Lussac's experiments it was never under 7l2 Q . A known vol- ume was introduced into a Volta's eudi- ometer, with platina wires, and an elec- tric 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 di- minution from the absorption of the car- bonic 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 ACI AC! The following are the results, referred to prussic acid vapour. Vapour, - - - f - 100 Diminution after combustion, - 78.5 Carbonic acid gas produced, 101.0 Nitrogen, - ... 46.0 Hydrogen, .... 55.0 During the combustion a quantity of oxygen disappears, equal to about 1 of the vapour employed. The carbonic acid produced represents one volume ; and the other fourth is supposed to be employed in forming vvat er ; for it is impossible to doubt that hydrogen enters into the com- position of prussic acid. From the laws of chemical proportions, M. Gay-Lussac con- cludes 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 hydro- gen. This result is evident for the car- bon ; and though, instead of 50 of nitro- gen and hydrogen, which ought to be the numbers according to the supposition, he obtained 46 for the first, and 55 for the se- cond, he ascribes the discrepancy to a por- tion of the nitrogen having combined with the oxygen to form nitric acid. The density of carbonic acid gas being, according 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 state- ment, 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 coincidence, 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 de- termination, analyzing prussic acid by passing its vapour through an ignited por- celain tube containing a coil of fine iron wire, which facilitates the decomposition of this vapour, as does it with ammonia. No trace of oxygen could be found in prussic acid. And again, by transmitting the acid in vapour over ignited peroxide of copper in a porcelain tube, he came to the same conclusion with regard to its con- constituents. They are, One volume of the vapour of carbon, Half a volume of hydrogen, Haifa volume of nitrogen, condensed into one volume; OT in weight, Carbon, 44.39 Nitrogen, 51.71 Hydrogen, 3.90 luo.oo This acid, when compared with the oth- er animal products, is distinguished by the great quantity of nitrogen it contains, by its small quantity of hydrogen, and espe- cially by the absence of oxygen. When this 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 ex- hibiting signs of decomposition. It begins by assuming a reddish brown colour, which becomes deeper and deeper, and it gradually deposites a considerable carbo- naceous 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, nothing remains but a dry charry mass, which gives no colour to water. Thus a prussiate of ammonia is formed at the ex- pense of a part of the acid, and an azoturet of carbon. When potassium is heated in prussic acid vapour mixed with hydrogen or nitrogen, there is absorption without in- flammation, and the m4tal is converted into a gray spongy substance, which melts:, and assumes a yellow colour. Supposing the quantity of potassium employed capable of disengaging from water a volume of hydrogen equal to 50 parts, we find after the action of the po- tassium, 1. That the gaseous mixture has experi- enced a diminution of volume amounting to 50 parts : 2. On treating this mixture with potash, and analyzing the residue by oxygen, that 50 parts of hydrogen have been produced : 3. And consequently that the potassium has absorbed 100 parts of prussie vapour; for there is a diminu- tion of 50 parts, which would obviously have been twice as great had not 50 part* of hydrogen been disengaged. The yel- low matter is prussiate of potash ; proper- ly a prusside of potassium, analogous in its formation to the chloride and iodide, when muriatic and hydriodic gases are made to act on potassium. The base of prussic acid thus divested of its acidifying hydrogen, should be call- ed, agreeably to the same chemical ana- logy, prussine. M. Gay-Lussac styles it cyanogen, because it is the principle which generates blue ; or literally, the blue- maker. Like muriatic and hydriodic acids also^ it contains half its volume of hydrogen. AC1 AC1 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 vol- time of nitrogen. This radical forms true prussides wivii metals. If the term cyanogen be objectionable as allying 1 it to oxygen, instead of chlorine and iodine, the term hydrocyanic acid must be equally so, as implying that it contains water. Thus we say hydronitric, hydromuriatic, and hydro phosphoric, to denote the aqueous compounds of 4he ni- tric, muriatic, and phosphoric acids. As the singular merit of M. Gay-Lussac, how- ever, has commanded a very general com- pliance among chemists with his nomen- clature, we shall use the term prussic acid and hydrocyanic indifferently, as has long been done with the words nitrogen and azote. The prusside or cyanide of potassium gives a very alkaline 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 per- fectly neutral. Knowing the composition t*f 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 oxy- gen. Thus we find the prime equivalent of this acid to be 33.846 ; and subtracting the weight of hydrogen, there remains 3,2.52 for the equivalent of cyanogen or prussine. But if we reduce the numbers representing the volumes to the prime equivalents adopted in this Dictionory, vi/. 0.75 for carbon, 0.125 for hydrogen, and 1.75 for nitrogen, we shall have" the relation of volumes slightly modified. Since the fundamental combining ratio of ox\ gen 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 52 primes carbon, - 1 prime hydrogen, 1 prime nitrogen, 0.125 1.750 volume hd. = 0.125X0.5555 volume nitr.- '-^XO.iM5 0.03471 0.48610 Sum = 0.93744 Or, as is obvious by the above calcula- tion, we may take 2 primes of carbon, 1 of hydrogen, and 1 of nitrogen, which direct- ly added together will g'ive the same re- sults, since by so doing we merely take away the common multiplier 0.5555. Thus we have-. 3.375 Which reduced to proportions per cent, give of Carbon, 44.444 Hydrogen, 3.704 Nitrogen, ---... 51.852 100.000 Barytes, potash, and soda combine with prussine, forming true prussides of these alkaline oxides ; analogous to what are vulgarly called oxy muriates 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 grer.t elevation of temperature takes place, which would occasion a dangerous explosion if the ex- periment were made upon considerable quantities. When the acid is diluted, the oxide dissolves rapidly, with a considera- ble heat, and without the disengagement of any gas. The substance formerly called prussiate of mercury is generated, which when moist may, like the muriates, still retain that name ; but when dry is a prus- side of the metal. When the cold oxide is placed in con- tact with the acid, dilated into a gaseous form by hydrogen, its vapour is absorbed in a few minutes. The hydrogen is un- changed. When a considerable quantity of vapour has thus been absorbed, the oxide adheres to the side of the tube, and on ap- plying heat, water is obtained. The hy- drogen 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 prusside of mer- cury to heat in a retort, the radical cyano- gen or prussine is obtained. See PRUSSINE. 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 or prus- sine at the positive, which remains dis- solved in the acid. This compound should be regarded as a hypoprussic or prussous acid. Since potash by heat separates the hydrogen of the prussic acid, we see that in exposing a mixture of potash and ani- mal matters to a high temperature, a true prusside or cyanide of potash is obtained, formerly called the prussian or phlogisti- cated alkali. When cyanide of potassium is dissolved in water, hydrocyanate of pot- -Jlsh is produced, which is decomposed by ACI ACI the acids without generating 1 ammonia or carbonic acid ; but when cyanide of pot- ash dissolves in water no change takes place ; and neither ammonia, carbonic acid, nor hydrocyanic vapour, is given out, unless an acid be added. These are the characters which distinguish 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 en- sues 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 Chemis- try, left by accident on a table a flask con- taining alcohol impregnated with prussic acid ; the servant, enticed by the agreea- ble flavour of the liquid swallowed a small flass of it. In two minutes she dropped own 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 time thereaf- ter." Dr. Magendie has, however, ventured to introduce its employment into medi- cine. He found it beneficial against phthi- sis and chronic catarrhs. His formula is the following: 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 Ib. or 7560 grs. Pure sugar, 1 oz. or 708| grs. And mixing the ingredients well together, he administers a table spoonful every morning and evening. A well written re- port of the use of the prussic acid in cer- tain diseases, by Dr. Magendie, was com- municated by Dr. Granville to Mr. Brande, and is inserted in the fourth volume of the Journal of Science. For the following ingenious and accu- rate process for preparing prussic acid for medicinal uses, I am indebted to Dr. Nim- mo of Glasgow : " Take of the ferroprussiate of potash 100 grains, of the protosulphate of iron 84^ grains ; dissolve them separately in four ounces of water, and mingle them. After allowing the precipitate of the pro- toprussiate of iron to settle, pour off the clear part, and add water to wash the sul- phate of potash completely away. To the protoprussiate of iron, mixed with four ounces of pure water, add 135 grains of the peroxide of mercury, and boil the VOL. T. [ 12 ] whole till the oxide is dissolved. With the above proportions of peroxide of mer- cury, the protoprussiate of iron is com- pletely decomposed. The vessel being kept warm, the oxide of iron will fall to the bottom, the clear part may be poured off to be filtered through paper, taking care to keep the funnel covered, so that crystals may not form in it by refrigeration. The residuum may be treated with more water, and thrown upon the filter, upon which warm water ought to be poured, until all the soluble part is washed away. By evaporation, and subsequent rest in a cool place, 145 grains of crystals of the prusside or cyanide of mercury will be procured in quadrangular prisms. " The following process for eliminating the hydrocyanic acid I believe to be new. Take of the cyanide of mercury in fine powder one ounce, diffuse it in two oun- ces of water, and to it, by slow degrees, add a solution of hydrosulphuret of bary- tes, made by decomposing sulphate of ba- rytes with charcoal in the common way. Of the sulphuret of barytes take an ounce, boil it with six ounces of water, and filter it as hot as possible. Add this in small por- tions to the cyanide of mercury, agitating the whole very well, and allowing suffi- cient time for the cyanide to dissolve, while the decomposition is going on be- tween it and the hydrosulphuret as it is added. Continue the addition of the hy. drosulphuret so long as a dark precipitate of sulphuret of mercury falls down, and even allowing a small excess. Let the whole be thrown upon a filter, and kept warm till the fluid drops through; add more water to wash the sulphuret of mer- cury, until eight ounces of fluid have pass- ed through the filter, and it has become tasteless. To this fluid, which contains the Srussiate of barytes, with a small excess of ydrosulphuret of barytes, add sulphuric acid, diluted with an equal weight of wa- ter, and allowed to become cold, so long as sulphate of barytes falls down. The ex- cess of sulphuretted hydrogen will be re- moved by adding a sufficient portion of carbonate of lead, and agitating very well. The whole ma^ now be put upon a filter, which must be closely covered ; the fluid which passes is the hydrocyanic acid, of what is called the medical standard strength. " Dr. Nimmo finds, that cyanide of mer- cury is capable of dissolving the mercuri- al peroxide. Hence, the above proportions must be strictly observed, if we wish to obtain this powerful medicine of uniform strength. He conceives, therefore, that the ferroprussiate of potash should be ta- ken for the basis of the calculation. Scheele found that prussic acid occa- sioned precipitates with only the following AC! AC1 three metallic Solutions, nitrates of silver, and mercury, and carbonate of silver. The first is white, the second black, the third green becoming 1 blue. In the Annals of Phil, for May 1820, Dr. Thomson gives an account of some metallic precipitates by a substance of a crystalline nature, which he obtained in the sublimation of Prussian blue at a red heat, and which he reckons hydrocyanatc of ammonia. But the nature of the substance is by no means demon- strated; and the precipitates differ so much from those of Scheele as to justify scepticism. Free prussic acid, for exiimple, gives with nitrate of mercury a black pre- cipitate; while Dr. Thomson's crystals give a white. Vauquelin found the crys- tals that sublime from prussian blue to be ammoniacal carbonate, and not hydrocy- anate. The hydrocyanatesare all alkaline, even when a great excess of acid is employed in their formation ; and they are decom- posed by the weakest acids. The hydrocyanate of ammonia crystal- lizes 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 temperature of 7l, it is capa- ble of bearing a pressure of 17.72 inches of mercury ; and at 97 its elasticity is equal to that of the atmosphere. Unfor- tunately this salt is charred and decom- posed with extreme facility. Its great vo- latility prevented M. Gay-Lussac from de- termining the proportion of its constitu- ents. What is known of the cyanides or prussides will be found under prussinc, or their bases. M. Gay-Lussac considers prus- sian blue as a hydrated cyanide of iron, or a cyanide having water in combination ; and M. Vauquelin, in a memoir lately read be- fore the Academy of Sciences, regards prussian blue as a simple hydrocyanate of iron. He finds that water impregnated with cyanogen can dissolve iron without changing it into prussian blue, and without the disengagement of any hydrogen gas, while prussiun blue was left in the undis- solved portion. But hydrocyanic acid con- Verts iron or its oxide into prussian blue without the help either of alkalis or acids. He conceives that cyanogen acts on iron and water as iodine does on water and a base ; and that a CYANIC acid is formed which dissolves a part of the iron, but al- so and at the same time hydrocyanic acid, which changes another part of the iron in- to prussian blue. He farther lays it down as a general rule, that those metals which, like iron, decompose water at the ordina- ry temperature of the atmosphere, form liydrocyanates ; and that those metals which do not possess this power, as silver and quicksilver, form only cyanides. Are we to regard the cyanic acid of M. Yau- quelin as a compound of one prime of oxy . gen, and one of cyanogen, or in other words, one of oxygen, two of carbon, and and one of nitrogen ? According to M. Vauquelin, very com- plex changes take place when gaseous cyanogen is combined with water, which leave the nature of cyanic acid involved iu great obscurity. The water is decompos- ed ; part of its hydrogen combines with one part of the cyanogen, and forms hy- drocyanic 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, cai-bonate, and cyanate of ammonia, are also found in the liquid ; and there still remain some carbon and nitrogen, which produce a brown deposite. Four and a half parts of water absorb one of gaseous cyano- gen, which communicates to it a sharp taste and smell, but no colour. The solu- tion in the course of some days, however, becomes yellow, and afterwards brown, in consequence of the intestine changes re~ lated above. Hydrocyanic acid is separated from pot- ash 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 prus- siate of potash, or prussiate of potash and iron. In illustration of this view, he pre- pared a hydrocyanate of potash and silver, which was quite neutral, and which crys- tallized in hexagonal plates. The solution of these crystals precipitates salts of iron and copper, white. Muriate of ammonia does not render it turpid ; but muriatic acid, by disengaging hydrocyanic acid, precipitates chloride of silver. Sulphu- retted hydrogen produces in it an analo- gous change. This compound, says M. Gay-Lussac, is evidently the triple hydro- cyanate of potash and silver ; and its for- mation ought to be analogous to that of the other triple liydrocyanates. " And as we cannot doubt/' adds he, " that hydro- cyanate of potash and silver is in reality, from the mode of its formation, a compound of cyanide of silver and hydrocyanate of potash, I conceive that the hydrocyanate of potash and iron is likewise a compound 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 per- fectly neutral, and then it does not decom- pose alum ; but the hydrocyanate of pot- ash, which is always alkaline, produces in it a light and flocculent precipitate of alu- mina. To the same excess of alkali we must ascribe the ochry colour of the pre cipitates which hydrocyanate of potash ACI AC1 forms with the persalts of iron. Thus the remarkable fact, which ought to fix the at- tention of chemists, and which appears to me to overturn the theory of Mr. Porrett, is, that hydroc^anate of potash cannot be- come neutral except when combined with the cyanides."* * ACID (CHLOHOCYATSTIC, orCHLOHornus- sic). 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 addition of sulphurous acid. Hydrocyanic acid thus altered had acquired the name of oxyprnssic, because it was supposed to have acquired oxygen. M. Gay-Lussac subjected it to a minute examination, and found that it was a compound of equal vo- lumes of chlorine and cyanogen, whence he proposed to distinguish it by the name of chlorocyanic acid. To prep are this com- pound he passed a current of chlorine into solution of hydrocyanic acid, till it destroy- ed the colour of sulphate of indigo ; and by agitating the liquid with mercury, he deprived it of the excess of chlorine. By distillation, afterwards, in a moderate heat, an elastic fluid is disengaged, which pos- sesses the properties formerly assigned to oxyprussic acid. This, however, is not pure chlorocyanic acid, but a mixture of it with carbonic acid, in proportions which vary so much, as to make it difficult to de- termine them. When hydrocyanic acid is supersaturat- ed with chlorine, and the excess of this last is removed by mercury, the liquid con- tains chlorocyanic and muriatic acids. Hav- ing put mercury into a glass jar till it was o-4thsfull, 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 disengaged. By de- grees the liquid itself was entirely expel- led, and swam on the mercury on the out- side. On admitting the air the liquid could not enter the tube, but only the mercury, and the whole elastic fluid condensed, ex- cept a small bubble. Hence it was con- cluded 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 sub- stance. The mixture of chlorocyanic and carbo- nic acids, has the following properties. It is colourless, its smell is very strong. A very small quantity of it irritates the pitui- tary membrane, and occasions tears. It reddens litmus, is not inflammable, and does not detonate when mixed with twice its bulk of oxygen or hydrogen. Its den- sity, determined by calculation, is 2.1 1U 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 efferves- cence 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 disengag- ed in abundance. To obtain the green precipitate from solution of iron, we must begin by mixing chlorocyanic acid with that, solution. We then add a little potash, and at last a little acid. If we add the al- kali before the iron, we obtain no green precipitate. M. Gay-Lussac deduces for the compo- sition of chlorocyanic acid 1 volume of car- bon -4- ^ a volume of azote -f- i 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 -f- 1 volume of carbonic acid -\- 1 volume of ammonia. The above three elements separately constituting two volumes, are condensed, by forming chlorocarbonic acid, into one volume. And since one volume of chlorine, and one volume of cyanogen, produce two volumes of chlorocyanic acid, the density of this last ought to be the halt' of the sum of the densities of its two con- stituents. Density of chlorine is 2.421, density of cyanogen 1.801, half sum 2.111, as stated above : Or the proportions by weight will be 3.375 = a prime equiv- alent of cyanogen -|- 4.45 = a prime of chlorine, giving the equivalent of chloro- cyanic acid == 7.825. " Chlorocyanic acid exhibits with potas.- sium almost the same phenomena as cyan- ogen. The inflammation is equally slow, and the gas diminishes as much in volume. The directions given by Dr. Thomson for forming chlorocyanic acid in the second volume of his System, 5th edition, p. 276, are apparently erroneous. He seems to have mistaken M. Gay-Lussac's ingenious plan for proving that this new acid is not naturally gaseous, for the process of ob- taining the acid itself, as prescribed both by him and M. Thenard. The chlorocy- anic and carbonic acids which come over in distillation, are to be condensed in water, or received over mercury. But the requisite process of distillation is not even hinted at by Dr. Thomson, whose chloro- cyanic acid must be a mixture of chloro- cyanic and muriatic acids.* * * ACID (FKUUOPHUSSIC). Into a solu- tion of the amber-coloured crystals, usual- ly called prussiate of potash, pour hydro- sulphuret of barytes, as long as any pre- cipitate falls. Throw the whole on a iii- ter, and wash the precipitate with cold water, Dry it ; and having- dissolved 100 ACI AC1 parts in cold water, add gradually SO of concentrated sulphuric acid; agitate the mixture, and set it aside to repose. The supernatant liquid is ferroprussic acid, cal- led by Mr. Porrett, who had the merit of discovering it, ferruretted chyazic acid. It has a pale lemon yellow colour, but no smell. Heat and light decompose it. Hydrocyanic acid is then formed, and white ferroprussiate 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 containsba base with which the ferroprussic acid forms an insoluble compound, then, agreeably to Berthollet's principle, it is capable of sup- planting it^ acid. When ferroprussiate of soda is exposed to voltaic electricity, the acid is evolved at the positive pole, with its constituent iron. Mr. Porrett consid- ers 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 pot- ash, and of barytes, will each, therefore, according to him, consist, of an atom of acid -f* an atom of base -{- two atoms of water. Dr. Thomson says, in his System, " From the analysis of Mr. Porrett it appears, that this acid is composed of Cyanogen, 8.904 Iron, 3.500 " This approaches to three atoms of cyanogen and one atom of iron, If we suppose this to be the real constitution of the acid, its constituents will be Cyanogen, 9.75 Iron, 3.50 " But such a composition is quite irreconcileable to the equivalent number for ferrocyanic acid, derived from the anaiysis of the ferrocyanate of barytes. This salt, according to the experiments of Mr. Porrett, is composed of Ferrocyanic acid, 34.31 6.813 Barytes, 49.10 9.750 Water, 16.59 100.00 " We see that by this analysis the equiva- lent number for ferrocyanic acid is 6.813. Now this agrees very nearly with the supposition that the acid is a compound of one atom cyanogen -f- one atom iron. For the weights of an atom of these bodies are as follows : Cyanogen, 3.25 Iron, 3.5 "The difference between 6.75 and 6.813 does not exceed one per cent. I am disposed, therefore, to consider this as the true constitution of ferrocyanic acid." It is a real misfortune to chemical stu- dents, when so elaborate a systematist as Dr. Thomson so readily scatters around him precipitate and dogmatical judgments, on discussions of such importance and delicacy as the present. There were no reasonable grounds whatever for peremp- torily deciding-, as he did, that the ferruret- ted chyazic acid of Mr. Porrett was a simple cyanide of iron, or a compound of cyanogen and iron. The mere similarity of two numbers, viz. the sum of the atoms of cyanogen and iron, and the equivalent of Mr. Porrett's acid, were apparently the chief, and surely very frivolous motives, for that erroneous determination. Mr Porrett expresses himself thus, in the Ann. of Phil, for September 1818. " It is a great satisfaction to nie to find that Dr. Thomson has abandoned the opinion which he entertained, that the ferruretted chyazic acid contained no hy- drogen, and was a compound of cyanogen and iron only ; an opinion which induced him to name it, in his System of Chemis- try, the ferrocyanic acid and its salts ferrocyanates. I was perfectly convinced, from many circumstances that occurred during my first experiments, that this opinion was erroneous, and should have combated it when it appeared in his Sys- tem, had I been fond of controversy, or been able to find time for carrying on such a course of experiments, as would perhaps have been requisite to produce conviction in others. As it was, I con- tented myself with expressing to my chemical friends, my dissent from Dr. Thomson's opinion on this subject; and I can venture to assure him, that whenever he makes experiments with the sulphuret- ted chyazic acid, he will be convinced that it also contains hydrogen, and that the names sulphocyanic, and sulphocyan- ates, are quite inappropriate ; equally so are the names proposed by Dr. Henry of ferroprussic, and sulphuretted prussic acids, as these names imply, that the prussic acid is contained in these com- pounds, instead of being merely the re- sult of a new play of affinities when they are decomposed." How little room there is for arbitrary decrees on every thing regarding the prussic combinations, we may readily judge, when we consider that M. Gay- Lussac, and M. Vauquelin, two of the first chemists of the age, have been led, after a series of admirable researches, to form views totally inconsistent with those re- sulting from Mr. Porrett's very ingenious ACI ACI experiments. On the relations of prussic acid and iron, the following observations by M. Vauquelin are important. Hydro- cyanic acid diluted with water, when pla- ced in contact with iron in a glass vessel standing over mercury, quickly produces Prussian blue, while, at the same time, hy- drogen gas is given out. The greatest part of the prussian blue formed in that operation, remains in solution in the liquid. It appears only when the liquid comes in contact with the air. This shows us that prussian blue, at a minimum of oxidize- ment, 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 be- comes agglutinated together at the bottom of the vessel, assumes a brown colour. Af- ter some days, the hydrocyanic acid being separated from the iron, and put in a small capsule under a glass jar, evaporated with- out leaving any residue. Therefore it had dissolved no iron. Hydrocyanic acid dis- solved in water, placed in contact with hydrate of iron, obtained by means of pot- ash, and washed with boiling water, fur- nished prussian blue immediately without the addition of any acid. Scheele has made mention of this fact. When hydro- cyanic acid is in excess on the oxide of iron, the liquor which floats over the prus- sian blue assumes, after some time, a beau- tiful purple colour. The liquor, when evaporated, leaves upon the edge of the dish circles of blue, and others of a pur- ple colour, and likewise crystals of this last colour. When water is poured upon these substances, the purple-coloured bo- dy 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 hydrocy- anic acid. Some drops of chlorine let fall into this liquid change it to blue, and a greater quantity destroys its colour entire- ly. It is remarkable that potash poured into the liquid thus deprived of its colour, occasions no precipitate 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) prus- sian blue is produced. They will remark, likewise, that cyanogen united to water dissolves iron. This is confirmed by the inky taste which it acquires, by the disap- pearance of its colour, and by the residue which it leaves when evaporated; yet prussian blue is not formed. These first experiments seem already to show that prussian blue is a hydrocyanate, and not a cyanide. The ammonia, and hydrocyanic acid, disengaged during the whole duration of the combustion of prussian blue, give a new support to the opinion, that this sub- stance is a hydrocyanate of iron ; and like- wise the results which are furnished by the decomposition of prussian blue by heat in a retort, show clearly that it con- tains both oxygen and hydrogen, which are most abundant towards the end, long after any particles of adhering water must have been dissipated. We shall conclude this subject with a comparison of Dr. Thomson's and Mr. Porrett's latest results. In the Anna's of Phil, for August 1818, we have a pupei 1 by Dr. Thomson, detailing numerous experi- ments which he had performed to ascer- tain the constitution of prussiate of potash and iron. " From this analysis," says he, " it follows that the acid in the triple salt (not reckoning the iron) is composed of Carbon, 0.6579 42.51 Azote, 0.7175 46.37 Hydrogen, 0.1722 11.12 1.5476 100.00 "From the preceding analysis, we see, that the triple prussiate of potash is com- posed as follows: ^r^WSoiH' 90 - - - 41.64 13.00 Potash, Water, 100.54 "We see, from the preceding analysis, that one-third part of the acid consists of iron, while two-thirds of its weight con- sists of carbon, azote, and hydrogen. The smallest number of atoms, which agrees nearly with the preceding proportions of the ingredients, is the following : 2 atoms carbon = 1.50 41.379 1 atom azote = 1.75 48.277 3 atoms hydrogen = 0.375 10.344 3.625 100.000" Mr. Porrett, besides his communica- tions to the Royal Society in 1814 and 1815, which Dr. Thomson justly describes " as very ingenious and important experi- ments, and conclusions respecting this acid," published two or three papers in the Annals of Philosophy, one of them in September 1818, already quoted, and an- other in October 1819. The latter pre- sents us with experiments of the same na- ture as Dr. Thomson's, from which the following inferences are drawn. " Collecting now from the preceding experiments the proportions of all the constituents of 100 gr. of ferrochyazate of potash, they appear as follows : ACI ACI Potash, Ferrochyazic acid Water, 41.68 gr. riron, 12.60 j Carbon 22.64 "S Azote, 13.32 l.Hydrogeii, 0.80 13.00 104.04 Being a surplus of four grains, arising 1 from the unavoidable inaccuracies in determin- ing experimentally, on small portions of the salt, the proportions of so many con- stituents. " These inaccuracies are easily removed by the application of the atomic theory ; for, by taking as our guide the weights of the atoms of each of the elements, we obtain the following numbers : 1 atom potash, 60. 40.34 latomferro-rif" 1 ' Jnn on^r chyazicacidJ 4 do. carbon, 30.0 20.17 fifi 95 1 1 do. azote, 17.5 11.76 Li do. hydrogen 1.250 0.84 2 atoms water, - - 22.50 15.13 1 at. ferrochyazate of potash, 148.75 100.00 Which doubtless gives the true propor- tions of the several elements of this salt." " We are now entitled to consider the atom of ferrochyazic acid as composed of 4 atoms of carbon = 30.00 45.3 1 atom of azote = 17.5 26.4 1 atom of hydrogen = 1.25 1.89 1 atom of iron = 17.5 26.4 66.25 99.99" The discordances of these two sets of results, are such as to destroy all confi- dence in them. Thus, Dr. Thomson, finds 15 per cent of iron; and Mr. Porett's corrected quantity of that metal, per cent, is only 11, a difference quite absurd in the present state of chemical analysis. Here follows a tabular comparison, of the acid constituents, exclusive of the iron: Dr. Thomson. Mr. Porrett. arbon, 42.51 61.54 Azote, 46.37 35.90 Hydrogen, 11.12 2.56 100.00 100.00 It has been supposed that Mr. Porrett's new acid is nothing but a hydrocyanate or prussiate of iron, which, from the muta- bility of its constituents, is easily decom- posed by heat and light ; and that the only permanent compound which that acid forms is in triple salts. This is the old opinion, and also the present opinion, of several eminent chemists. These com- pounds we shall call ferroprussiates. M. Vauquelin and M. Thenard style them ferruginous prussiates. Ferroprusxate of potash. Into an egg- Chapped iron pot, brought to moderate ignition, project a mixture of good pearl- ash and dry animal matters, of which hoofs and horns are best, it the proportion of two parts of the former to five of the latter. Stir them well with a fiat 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 pro- duct diminished. Allow it to cool, dis- solve it in water, clarify the solution by filtration or subsidence, evaporate, and, on cooling, yellow crystals of the ferro- prussiate of potash will form. Separate these, redissolve them in hot \vateiv and by allowing the solution to cool very slowly, larger and very regular crystals nay be had. This salt is nw manufac- tured in several parts of Great Britain, on the large scale ; and therefore the ex- perimental chemist need not incur the trouble and nuisance of its preparation. Nothing can exceed in beauty, purity, and perfection, the crystals of it prepared at Campsie, by Messrs Mackintosh and Wilson. An extemporaneous ferroprussiate of potash may at any time be made, by acting on prussian blue, with pure carbonate of potash, prepared from the ignited bicar- bonate 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 evapor- ation, and allow it slowly to cool. Qua- drangular bevelled crystals of the ferro- prussiate of potash will form. This salt is transparent, and of a beau- tiful lemon or topaz yellow. Its specific gravity is 1.830. It has a saline, cooling, but not unpleasant taste. In large crystals it possesses 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 moder- ately heated; and then appears of a white colour, as happens to the green copperas; ACI ACI 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 for- mation, we see that even that temperature is compatible with the existence of the acid, provided it be not too long contin- ued. Water at 60 dissolves 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 scru- pulosity have assigned to that liquid the hereditary sinecure of screening the salt from the imaginary danger of atmospheri- cal action. It is not altered by the air. Exposed in a retort to a strong red heat, it yields prussic acid, ammonia, carbonic acid, and a coaly residue consisting of charcoal, metallic iron, and potash. 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 afterwards, treated with liquid chlorine, yields a prussian blue, equivalent to fully one-third of the salt employed. Neither sulphuretted hydrogen, the hydrosul- phurets, nor infusion of galls, produce any change on this salt. Red oxide of mer- cury acts powerfully on its solution at a moderate heat. Prussiate of mercury is formed, which remains in solution ; while peroxide of iron and metallic mercury precipitate. 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 decom- posed by almost all the salts of the perma- nent metals. The following table presents a view of the colours of the metallic pre- cipitates thus obtained. Solutions of Give a Manganese, "White precipitate. Protoxide of iron, Copious white. Deutoxide of iron, Copious clear blue. Tritoxide of iron, Copious dark blue. Tin, White. Zinc, White. Antimony, White. Uranium, Blood coloured. Cerium, White. Cobalt, Grass green. Titanium, Green. Bismuth, White. Protoxide of copper, White. Deutoxide of copper, Crimson brown-. Nickel, Apple green. Lead, White. Deutoxide of mercury, White. Silver, White, passing to blue, in the air. Palladium, Olive. Rhodium, Platinum, and Gold,- If some of these precipitates, for exam- ple those of manganese or copper, be di- gested 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, therefore, contain a quantity of iron. I think this fact is very favourable to the theory of Mr. Porrett; and scarcely explicable on any other sup- position. This salt is composed of the following constituents, by the latest ana- lyses. Mr. Porrett. Dr. Thomson. Potash, 40.34 41.64 Ferrochyazic acid, 44.53 45.90 Water, 15.13 13.00 100.00 100.54 The small excess in the latter sum, Dr. Thomson thinks, may be equally divided among all the ingredients. We shall then have for his analysis : Potash, 41.41 Acid, 45.67 Water, 12.92 100.00 We have seen the enormous discrepant cies with regard to the estimates of the ul- timate acid constituents by these two ex- perimentalists ; and if we consider the di- rectness and simplicity of the methods by which the primary constituents of the salt may be ascertained, the above differences also seem too great. By a well regulated desiccation, the water of crystallization may be pretty nearly determined; and the concurring results of experiment give for its quantity 13 per cent. Now the action of nitric acid properly conjoined with that of heat, should decompose and dissipate the gaseous part of the acid, and convert the iron into an insoluble peroxide ; the weight of potash may then be exactly de- termined, first by saturation with acid, and secondly, by the weight of resulting salt. In fact had Mr. Porrett adhered to his ex- perimental numbers, and not modified them by his atomical notions, we should have had the following results, which are probably correct. Potash, 41.68 Water, 13.00 Ferrochyazic acid, 45.32 100.00 And from this real analysis, we deduce directly from the proportion of potash "= 41.68, the apparent prime equivalent of this neutral salt to be = 14.29 ; or rather its double, 28.58. If we make it 28.275, then we would have the following hypothetical arrange- ment of proportions, ACI ACI 2 primes of potash, = 11.900 42.04 2 do. of ferrochyazic acid, = 13.000 45 96 3 do. of water, = 3.375 12.00 28.275 100.00 We have treated the subject of the fer- roprussiate of potash at considerable de- tail, since it is one of the most valuable re -agents, which the chemist possesses, in metallic analysis. Ferroprussiate of soda may be prepared from prussian blue, and pure soda, by a similar process to that prescribed for the preceding salt. It crystallizes in^bur-si- ded prisms, terminated by dihedral sum- mits. 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 boiling water. As the solution cools, crystals separate. Their specific gravity is 1.458. They are said by Dr. John to be soluble in alcohol. Ferroprussiate of lime may be easily form- ed from prussian blue and lime-water. Its solution yields crystalline grains by evapo- ration. Ferroprussiate of barytes may be formed in the same way as the preceding species ; or much more elegantly by Mr. Porrett's process, described already in treating of the ferroprussic acid. Its crystals are rhomboidal prisms, of a yellow colour, and soluble in 2000 parts of cold water, and 100 of boiling water. By Mr. Porrett's second account of this salt, it is composed of Expert. Theory. Acid, 41.5 41.49 1 atom 84.84 Barytes, 47.5 47.44 1 atom 97.00 Water, 11.0 11.07 2 atoms 22.64 100.0 100.00 204.48 These results were given in the Annals of Philosophy for September 1818. In Dr. Thomson's System, published in October 181?, we have the following statement: " Mr. Porrett has analyzed this salt with much precision. According to his expe- riments, it is composed of Ferrocyanic acid, Barytes, Water, 34.31 49.10 16.59 100.00" In the Annals for October 1819, Mr. Porrett gives as its true proportions, 1 atom ferrochyazic ucid, 66.25 35.66 1 atom barytes, 97. 52.22 2 atoms water, 22.5 12.12 185.75 100.00 The discrepancies are singular, with a substance so unalterable and so easily as- certained as barytes ; for Dr. Thomson's quotation gives of this substance 49.1 per cent. ; the second account makes it 47.5 ; and the last 52. 22. The quantity of bary- tes may be determined absolutely, without being deduced from, or entangled with, the estimate of water or acid. Ferroprussiate of strontian and magnesia have also been made. Ferroprussiate of iron. With the pro- toxide of iron and this acid we have a white powder, which, on exposure to air, be- comes blue, passing into deutoferroprussiate of iron, or prussian blue. We have already described the method of making the fer- roprussiate of potash, which isthe first step in the manufacture of this beautiful pig- ment. This is usually made by mixing to- gether one part of the ferroprussiate of potash, one part of copperas, and four parts or more of alum, each previously dis- solved in water. Prussian blue, consist- ing of the deutoferroprussiate cf iron, mix- ed with more or less alumina, precipitates. It is afterwards dried on chalk stones, in a stove. Pure prussian blue is a mass of an ex- tremely deep blue colour, insipid, inodo- rous, and considerably denser than water. Neither water nor alcohol has an}' action on it. Boiling solutions of potash, soda, lime, barytes, and strontites decompose it ; forming on one hand soluble ferroprus- siates with these bases, and on the other a residue of brown deutoxide of iron, and a yellowish brown subferroprussiate of iron. This last, by means of sulphuric, ni- tric, or muriatic acid, is brought back to the state of a ferroprussiate, by abstracting the excess of iron oxide. Aqueous chlo- rine changes the blue to a green in a few minutes, if the blue be recently precipitat- ed. Aqueous sulphuretted hydrogen, re- duces the blue ferroprussiate to the white protoferroprussiate. Its igneous decomposition in a retort has lately been executed by M. Vauquelin with minute attention. He regards it as a hy- drocyanate or mere prussiate of iron ; but the changes he describes are very com- plex, nor do they invalidate Mr. Porrett's opinion, that it is a combination of red ox- ide of iron, with a ferruretted acid. The general results of M. Vauquelin's analysis, were hydrocyanic acid, hydrocyanate of ammonia, an oil soluble in potash, crystal- line needles, which contained no hydrocy- anic acid, but were merely carbonate of ammonia; and finally, a ferreous residue slightly attracted by the magnet, and con- taining a little undecomposed prussian blue. If we are to regard prussian blue as a deutoferroprussiate of iron, then by Mr. Porrett's latest considerations, it would be composed of ACI ACI 1 atom acid, = 6.625 35.1 1 atom red oxide, = 10.000 53.0 2 atoms water, = 2.250 11.9 18.875 100.0 Dr. Thomson, after reporting 1 it from Mr. Porrettto consist of Acid, 53.38 6.75 Peroxide of iron, 34.23 4.328 Water, 12.o9 100.00 thinks it likely that the true composition is, Ferrocyanic acid, 6.75 Peroxide of iron, 5.00 Proust, in the Annales de Chimie, voL Ix. states, that 100 parts of prussian blue, without alum, yield 0.55 of red oxide of iron by combustion; and by nitric acid, 0.54. 100 of prussiate of potash and iron, lie further says, afford, after digestion with sulphuric or nitric acid, 35 parts of prus- sian blue. If we compare with this, Mr. Forrett's earliest estimate of 34.23 per ent of ferreous peroxide, besides the third of the weight of the acid, = 17.79, which being metallic iron, is equivalent to 25.4 of peroxide, we shall have the sum 59.63, as the quantity of peroxide in 100 of prussian blue, calling the atom of iron 3.5, and of peroxide 5.0. Or if we take Dr. Thom- son's correction, we have the following numbers, supposing it to consist of 1 atom acid, 6.75 48.2 1 peroxide, 5.00 35.7 2 water, 2.25 16.1 14.00 100.0 or perhaps 1 atom acid, 6.75 52.3 1 peroxide, 5.00 39.0 1 water, 1.125 8.7 12.875 100.0 To the 35.7 of peroxide base in the first, if we add 23 for the equivalent of peroxide in its acid, we have 58.7 for the whole per- oxide in 100 gr. ; and to the 39 of peroxide in the second, it we add 25 for the equiva- lent peroxide in the acid, we have the sum of 64 ; both, quantities considerably greater than Mr. Proust's.* * Sci.pHuuepiiussTC ACID ; the sulphu- retted 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. Sulphu- ret of iron is formed, and a colourless liquid containing the new acid combined with potash, mixed with hyposulphite and sul- phate of potash. Render this liquid sen- sibly sour, by the addition of sulplmric acid. Continue the boiling for a little, and when it cools, add a little peroxide of manganese in fine powder, which will give Vox* r [13] the Kquid a fine crimson colour. To the filtered liquid add a solution containing persulphate of copper, and protosulphate of iron, in the proportion of two of the for- mer salt to three of the latter, until the crimson colour disappears. Sulphuro- prussiate of copper falls. Boil this with a solution of potash, which will separate the copper. 'Distil the liquid mixed with sul- phuric acid in a glass retort, and the pecu- liar acid will con.e over. By saturation with carbonate of barvtes, and then throw- ing down this by the equivalent quantity of sulphuric acid, the sulphuroprussic acid is obtained pure. It is a transparent and colourless liquki, possessing a strong 1 odour, somewhat re- sembling acetic acid. Its specific gravity is only 1.022. It dissolves a little sulphur at a boiling 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 de- composed. 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.*'00 2 carbon, = 1.508 1 azote, = 1.754 I hydrogen, =. 0.132 7.394 This is evidently an atom of the hydro* cyanic 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 metallic salt. When cyanogen and sul- Ehuretted hydrogen were mixed together y M. Gay Lussac in his researches on the prussic principle, he found them to con- dense into yellow acicular crystals. Mr. Porrett has since remarked, that these crystals are not formed when the two gases are quite diy, 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 ef- fect on solutions of iron ; it contains nei- ther prussic nor sulphuretted chyazic acid, yet this acid is formed in it when it is mix- ed first with an alkali and then with an acid. The same treatment does not form any prussic acid. The facility with which the atomic hy- pothesis may be twisted to any theoretical perversion, is well exemplified in the fol- lowing passage : " The weight of an atom of hydrocyanic acid is 3.375, and that of an atom of sulphur 2. But 6.328" (Mr. Porrett's first proportion of sulphur) " not being a multiple of two, this statement does not actjord we.ll with tbjs atqrnic tliet^ ACI ACI sy. It agrees much better with that theo- ry, if we suppose the acid to be a com- pound of sulphur and cyanogen. Its con- stitution will then be, Sulphur, 1.20 100 6.09 Cyanogen, 0.64 53.3 3.25 Thus we see that it is a compound of 1 atom of cyanogen and 3 atoms of sulphur." Thomson's System, Vol. ii. p. 292. This procedure looks more like leger- demain than philosophical research. Had Dr. Thomson contented himself with say- ing that the statement of Mr. Porrett did not accord with the atomic theory, he would have said right ; and there he should have left the matter, or have insfituted experiments to settle the point. But to create a new genus of compounds, sulphur and cyanogen, and erect it into a new acid, on such a frivolous conceit, throws an air of ridicule on the science. Nay further, the Doctor describing M. Gay-Lussac's crystalline compound of sulphuretted hy- drogen and cyanogen, says, that " as far as its description goes, this substance agrees exactly with the sulphuretted chyazic acid of Mr. Porrett. Tf we abstract the hy- drogen of the sulphuretted hydrogen, which probably did not enter into the com- position of the compound, it will be a com- pound of 1 atom cyanogen, and 1 atom sulphur, or in whole numbers of 2 atoms cyanogen and 3 atoms sulphur. So that it will contain just half the quantity of sul- phur which Mr. Porrett found." M. Gay- Lussac expressly states that the yellow needles obtained from the joint action of cyanogen and sulphuretted hydrogen are *' composed of one volume of cyanogen, and 1^ volume of sulphuretted hydrogen." So that instead of containing no hydrogen, this substance contains half a volume more than hydrocyanic acid. The sulphuroprussiates have been ex- amined only by Mr. Porrett. That of the red oxide of iron is a deliquescent salt, of a beautiful crimson colour. It may be ob- tained in a solid form by an atmosphere artificially dried. A concise account of these sJls is given in the 5th Vol. of the Annals of Philos.* * 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 urinary calculi, in dilute nitric acid, an ef- fervescence takes place, and the lithic acid is dissolved, forming a beautiful pur- ple liquid. The excess of nitric acid being neutralized with ammonia, and the whole concentrated by slow evaporation, the co- lour of the solution becomes of a deeper purple, and dark red granular crystals, sometimes of a greenish hue externally, soon begin to separate in abundance. These crystals are a compound of ammo ma 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 drop- ped into dilute sulphuric acid, "which, uniting with the potash, left the acid prin- ciple 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 co- lour. 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 wa- ter. One-tenth of a grain, boiled for a con- siderable time in 1000 grains of water, was not entirely dissolved. The water, how- ever, assumed a purple tint, probably, Dr. Prout thinks, from the formation of a lit- tle purpurate of ammonia. Purpuric 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, alkaline earths, and metallic oxides. It is capable of expelling carbonic acid from the alkaline carbonates by the assistance of heat, and does not combine with any other acid. These are circumstances suffi- cient, as Dr. Wollaston observed, to dis- tinguish it from an oxide, and to establish its character as an acid. Purpurate of ammonia crystallizes in quadrangular 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 beauti- ful deep carmine, or rose-red colour. It has a slightly sweetish taste, but no smell, Purpurate of potash is much more soluble ; of soda is less; that of lime is nearly in- soluble ; those of strontian and lime are slightly soluble. All the solutions have the characteristic colour. Purpurate of magnesia is very soluble ; and in solution, of a very beautiful colour. A solution of acetate of zinc produces with purpurate ACT ACI of ammonia, a solution and precipitate of a beautiful gold-yellow colour ; and a most brilliant iridescent pellicle, in which green and yellow predominate, forms on the sur- face of the solution. Dr. Prout conceives the salts to be anhydrous, or void of wa- ter, and composed of two atoms of acid and one of base. The purpuric acid and its compounds probably constitute the ba- ses 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 ammonia, and perhaps occasionally to the purpurate of soda. The solution of lithic acid in nitric acid -stains the skin of a permanent colour, which becomes of a deep purple on ex- posure to the sun. These apparently sound experimental deductions of Dr. Prout, kave been called in question by M. Vau- ACI AC1 ash, 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 16.84, hydro- gen 10.* * Aciu (PrROttALic). When malic or sorbic acid, for they are the same, is dis- tilled in a retort, an acid sublimate, in white needles, appears in the neck of the retort, and an acid liquid distils into the receiver. This liquid, by evaporation, affords crystals, constituting a peculiar acid, to which the above name has been given. They are permanent in the air, ifielt 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 re- tort, they are partly sublimed in needles, and are partly decomposed. They are very soluble in strong alcohol, and in dou- ble their weight of water, at the ordinary temperature. The solution reddens vege- table blues, and yields white flocculent precipitates with acetate of lead and ni- trate 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 wa- ter, after which, by gentle evaporation, the pyromalate of barytes may be obtain- ed in silvery plates. These consist of 100 acid, and 185.142 barytes, or in prime equivalents, of 5.24+ 9.70. Pyromalate of potash may be obtained in feather formed crystals, which deli- quesce. Pyromalate of lead forms first a white flocculent precipitate, soon passing into a semi-transparent jelly, which by di- lution and filtration from the water, yields brilliant pearly looking needles. The white crystals that sublime in the original distillation, are considered by M. Las- saigne as a peculiar acid.* * ACID (PTHOTARTA.RIC). Into a coated glass retort introduce tartar, or rather tar- taric acid, till it is half full, and fit to it a tubulated receiver. Apply heat, which is to be gradually raised to redness. Pyro- tartaric acid of a brown colour, from im- purity, is found in the liquid products. We must filter these through paper pre- viously wetted, to separate the oily mat- ter. Saturate the liquid with carbonate of potash ; evaporate to dryness; reclis- solve, and filter through clean moistened .paper. By repeating this process of eva- poi-ation, 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 sulphuric acid. There passes over into the receiver, first of all a liquor con- taining evidently acetic acid; but towards the end of the distillation, there is con- densed in the vault of the retort, a white and foliated sublimate, which is the pyro- tartaric acid, perfectly pure. It has a very sour taste, and reddens powerfully the tincture of turnsole. Heat- ed in an open vessel, the acid rises in a, white smoke, without leaving the char- coaly residuum, 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 pyrotartrates, of which those of potash, soda, ammonia, barytes, strontites, and lime, are very soluble. That of pot- ash is deliquescent, soluble in alcohol, ca- pable of crystallizing in plates, like the acetate of potash. This pyrotartrate pre- cipitates both acetate of lead and nitrate of mercury, whilst the acid itself precipi- tates only the latter. Rose is the discover- er of this acid, which was formerly con- founded with the acetic. * * Acn> (ROSASIC). There is deposited from the urine of persons labouring under intermittent and nervous fevers, a sedi- ment of a rose colour, occasionally in red- dish crystals. This was first discovered to be a peculiar acid by M. Proust, and afterwards examined by M. Vauquelin. This acid is solid, of a lively cinnabar hue, without smell, with a faint taste, but red- dening litmus very sensibly. On burning coal it is decomposed into a pungent va- pour, which has not the odour of burning animal matter. It is very soluble in water, and it even softens in the air. It is solu- ble in alcohol. It forms soluble 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 intimate a union, that the lithic acid in precipitating from urine carries the other, though a deliquescent substance, down along with it. It is obtained pure by acting on the sediment of urine with alcohol. See ACID (PuRpcRifc).* * ACID (SACLACTIC). See Aciu (Mucic).* * 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 condensible products are chiefly fat, altered by the fire, mixed with a little acetic and sebacic acids. Treat this pro- duct with boiling water several times, agi- tating 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 precipitate 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, ACI ACI sttid pour upon it its own weight of sulphu- ric 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 lit- mus paper; its specific gravity is above that of water and its crystals are small white needles of little coherence. Ex- posed to heat, it melts like fat, is decom- posed, and partially evaporated. The air has no effect upon it. It is mxich more soluble in hot than in cold water; hence, boiling water saturated with it, assumes a nearly solid consistence on coohng. Al- cohol dissolves it abundantly at ordinary temperature. With the alkalis it forms soluble neutral salts ; but if we pour into their concentra- ted 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 theaccount given by M. Thenard ef this acid, in the 3d volume of his Traite de Chimie, published in 1815. Berzelius, inl 806, 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 com- mon benzoic acid. M. Thenard takes no notice of M. Berzelius whatever, but con- cludes his account by stating, that it has been known only for twelve or thirteen 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, according to the process used in the preparation.* * ACID (SOKBIC). The acid of apples, called malic, may be obtained most conve- niently and in greatest purity from the berries of the mountain ash, called sorbiis, or pyrus aiicuparia, and hence the present name, sorbic acid. This was supposed to be anew and peculiar acid by Mr. Don- ovan and M. Vauquelin, 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 fermentation, 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 quan- tity 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 deposites 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 hydrogen 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 sulphu- retted hydrogen. It is now a solution of sorbic scid. When it is evaporated to the consistence of a sirup, it forms mammelated masses of a crystalline structure. It still contains a considerable quantity of water, and delU quesces when exposed to the air. Its so- lution is transparent, colourless, void of smell, but powerfully acid to the taste. Lime and barytes waters are not precipi- tated by solution of the sorbic acid,although the sorbate of lime is nearly insoluble. One of the most characteristic properties of this acid, is the precipitate which it gives with the acetate of lead, which is at first white and flocculent, but afterwards as- sumes a brilliant crystalline appearance. With potash, soda, and ammonia, it forms crystallizable salts containing an excess of acid. That of potash is deliquescent. Sor- bate of barytes consists, according to M. Vauquelin, of 47 sorbic acid, and 53 bary- tes in 100. Sorbate of lime well dried, ap- peared to be composed of 67 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 sorbate contains 12.5 per cent of water. M. Vauquelin. says that Mr. Donovan was mistaken 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 moie so in boiling water : as it cools it crystallizes in the beautiful white, brilliant, and shining needles, of which we ACI ACI iave already' spoken. A remarkable phe- nomenon 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 sufficient quantity of fluid to dissolve it, is partially melted, and is at first -kept on the surface by the force of ebulli- tion, but after some time falls to the bot- tom, and as it cools becomes strongly fix- ed to the vessel. To procure sorbic acid, M. Bracennot saturates with chalk the juice of the scarce- ly ripe berries, evaporates to the consis- tence of a sirup, removing the froth ; and a granular sorbate falls, which he decom- poses by carbonate 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 7.0 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 nly one quite neutral, we shall have the following relation of prime equivalents : Theory. Exp. 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 The approximation of these sets of pro- portions, illustrates and confirms the accu- racy of M. VauquelhVs researches. The calcareous salt having been pro- cured in a neutral state, by the addition of carbonate of potash to its acidulous solu- tion, it might readily be mixed with as much carbonate of lime as would diminish the apparent equivalent of acid from 7.50 to 7.230 ; especially as the barytic com- pound 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 cut 7.5, as its ultimate analysis indicates. As the pure sorbic acid appears to be without 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 ( S t B ERI c) . This acid was obtain- ed by Brugnatelli from cork, and after- wards more fully examined by Bouillon la Grange. To procure it, pour on cork, grated to powder, six times its weight of nitric acid, of the specific gravity of 1.26, in a tubulated retort, and distil the mix- ture with a gentle heat, as long as any red fumes arise. As the distillation advances, . a yellow matter, like wax, appears on the surface of the liquid in the retort. While j its contents continue hot, pour them into j a glass vessel, placed on a sand-heat, and j keep them continually stirring with a glass rod; by which means the liquid will gra- dually grow thicker. As soon as white penetrating vapours appear, let it be re- moved from the sand-heat, and kept stir- ring till cold. Thus an orange-coloured mass will be obtained, of the consistence of honey, of a strong sharp smell while hot, and a peculiar aromatic smell when cold. On this, pour twice its weight of boiling water, apply heat till it liquefies, and filter. As the filtered liquor cools, it deposites a powdery sediment, and acquires a thin pellicle. Separate the sediment by filtration, and evaporate the fluid nearly lo dryness. The mass thus obtained is the suberic acid, which may be purified by saturating with an alkali, and precipitating by an acid, or by boiling it with charcoal powder. * M. Chevreul obtained the suberic acid by mere digestion of the nitric acid on grated cork, without distillation, and pu- rified it by washing with cold water. 12 parts of cork may be made to yield 1 of acid. 'When pure, it is white and pulve- rulent, having a feeble taste, and little ac- tion 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 preci- pitate when poured into acetate of lead, nitrates of lead, mercury, and silver, mu- riate of tin, and protosulphate of iron. It affords no precipitate with solutions of copper or zinc. The suberates of potash, soda, and ammonia, are very soluble. The two latter may be readily crystallized. Those of barytes, lime, magnesia, and alu- mina, are of sparing solubility.* ACID (SucciNic.) It has long been known that amber, when exposed to dis- tillation, affords a crystallized substance, which sublimes into the upper part of the vessel. Before its nature was understood it was called salt of amber , but it is now known to be a peculiar acid, as Boyle first discovered. The crystals are at first con- taminated with a little oil, which gives them a brownish colour; but they maybe purified by solution and crystallization, repeated as often as necessary, when they will become transparent and shining. Pott recommends to put on the filter, through \vhich the solution is passed, a little ootion AC! ACI previously wetted with oil of amber. Their figure is that of a triangular prism. Their taste is acid, and they redden the blue co- lour of litmus, but not that of violets. They are soluble in less than two parts of boil- ing alcohol, in two parts of boiling water, and in twenty -five of cold water. M. Planche of Paris observes, that a considerable quantity might be collected in making amber varnish, as it sublimes while the amber is melting for this pur- pose, and is wasted. * Several processes have been proposed for purifying this acid : that of Richter ap- pears to be the best. The acid being dis- colved in hot water, and filtered, is to be saturated with potash or soda, and boiled with charcoal, which absorbs the oily mat- ter. 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 separated. Nitrate or muriate of barytes, will show whether any sulphuric acid remains mixed with the suc- cinic solution ; and if so, it may be with- drawn 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 upon it. It is so- luble in both water and alcohol, and much more so when they are heated. Its prime equivalent, by Berzelius, is 6.26 ; and it is composed of 4.51 hydrogen, 47.6 carbon, 47.888 oxygen in 100, or 2 -f 4 + 3 primes.* With barytes and lime the succinic acid forms salts but little soluble ; and with magnesia it unites into a thick gummy substance. The succinates of potash and ammonia are crystallizable and deliques- cent ; that of soda does not attract mois- ture. 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 alco- hol and sulphuric acid together with heat. It seems probable, that this acid is merely the hypo-sulphuric, combined with a pe- culiar oily matter.* ACID (SULPHURIC.) When sulphur is heated to 180 or 190 in an open vessel, it melts, and soon afterward emits a blu- ish flame, visible in the dark, but which, in open day -light, has the appearance 'of a white fume. This flame has a suffocating smell, and has so little heat that it will not set fire to flax, or even gunpowder, so that in this way the sulphur may be entirely consumed out of it. If the heat be still augmented, the sulphur boils, arid sudden- ly bursts into a much more luminous flatnfc, the same suffocating vapour still continu- ing to be emitted. The suffocating vapour of sulphur is imbibed by water, with which it forms the fluid formerly called volatile vitriolic, now sulphurous acid. If this fluid be expose* for a time to the air, it loses the sulphure- ous smell it had at first, and the acid be- comes more fixed. It is then the fluid which was formerly called the spirit of -vi- triol. Much of the water may be driven off by heat, and the dense acid which re- mains is the sulphuric acid, commonly called oil of vitriol; a name which was pro- bably given to it from the little noise it makes when poured out, and the unctuous feel it has when rubbed between the fin- gers, produced by its corroding and de- stroying the skin, with which it forms a soapy compound. The stone or mineral called martial py- rites, which consists for the most part of sulphur and iron, is found to be converted into the salt vulgarly called green vitriol, but more properly sulphate of iron, by ex- posure to air and moisture. In this natu- ral process the pyrites breaks and falls in pieces; and if the change take place ra- pidly, a considerable increase of tempera- ture follows, which is sometimes sufficient to set the mass on fire. By conducting this operation in an accurate way, it is found that oxygen is absorbed. The sulphate is obtained by solution in water, and subse- quent evaporation ; by which the crystals of the salt are separated from the earthy impurities, which were not suspended in the water. The sulphuric acid was formerly obtain- ed in this country by distillation from sul- phate of iron, as it still is in many parts abroad: the common green vitriol is made use of for this purpose, as it is to be met with at a low price, and the acid is most easily to be extracted from it. With re- spect to the operation itself, the following; particulars should be attended to: First, the vitriol must be calcined in an iron or earthen vessel, till it appears of a yellow* ish red colour: by this operation it will lose half its weight. This is done in order to deprive it of the greater part of the wa- ter which it has attracted into its crystals during the crystallization, and which would otherwise, in the ensuing distillation, great- ly weaken the acid. As soon as the calci- nation is finished, the vitriol is to be put immediately, while it is warm, into a coat- ed earthen retort, which is to be filled two-thirds with it, so that the ingredients may have sufficient room upon being dis- tended by the heat, and thus the bursting of the retort be prevented. It will be most advisable to have the retort immedi- ately enclosed \jn brick-work in a reverbc- ACI ACI feitory furnace, and to stop up the neck of it till the distillation begins, in order to prevent the materials from attracting 1 fresh humidity from the air. At the beginning 1 of the distillation the retort must be open- ed, and a moderate fire is to be applied to it, in order to expel from the vitriol all that part of the phlegm which does not taste strongly of the acid, and which may be received in an open vessel placed un- der the retort. But as soon as there ap- pear any acid drops, a receiver is to be added, into which has been previously poured a quantity of the acidulous fluid which has come over, in the proportion of half a pound of it to twelve pounds of the calcined vitriol; when the receiver is to be secured with a proper luting. The fire is now to be raised by little and little to the most intense degree of heat, and the receiver carefully covered with wet cloths, and, in winter time, with snow or ice, as the acid rises in the form of a thick white vapour, which toward the end of the ope- ration becomes hot, and heats the receiv- er to a great degree. The fire must be continued at this high pitch for several days, till no vapour issues from the retort, nor any drops are seen trickling down its sides. In the case of a great quantity of vitriol being distilled, M. Bcrnhardt. has observed it to continue emitting vapours in this manner for the space often days. "When the vessels are quite cold, the re- ceiver must be opened carefully, so that none of the luting may fall into it; after which the fluid contained in it is to be poured into a bottle, and the air carefully excluded. 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 ther 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, and its consistence is owing to a mixture of sulphurous acid, which occasions it to become solid at a moderate temperature. * It has been lately stated by A^ogel, 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 has been supposed to constitute 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 jt continues solid, but at tempe- ratures above this it becomes a colourless vapour, which whit-en? rw front-act with air. Dropped into water in small quanti- ties, it excites a hissing noise, as if it were red hot iron ; in larger quantities it pro- duces a species of explosion. It is said to be convertible into ordinary sulphuric acid, by the addition of a fifth of water. It dissolves sulphur, and assumes a blue, green, or brown colour, according to the proportion of sulphur dissolved. The spe- cific gravity of the black fuming sulphuric acid, prepared in large quantities from copperas, at Nordhausen, is 1.896. Its constitution is not well ascertained.* The sulphuric acid made in Great Bri- tain is produced by the combustion of sul- phur. There are three conditions requi- site in this operation. Oxygen must be present to maintain the combustion ; the vessel must be so close as to prevent the escape of the volatile matter which rises, and water must be present to imbibe it. For these purposes, a mixture of eight parts of sulphur with one of nitre is placed in a proper vessel, enclosed within a cham- ber 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 conside- rable time by virtue of the supply of oxy- gen 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 concentrated by dis- tillation. * Such was the account usually given of this operation, till MM. Clement and Des- ormes showed, in a very interesting me- moir, its total inadequacy to account for the result. 100 parts of nitre, judiciously managed, will produce, with the requisite quantity of sulphur, 2000 parts of concen- trated sulphuric acid. Now these contain 1200 parts of oxygen, while the hundred parts of nitre contain only 39^ of oxygen ; being not gVh part of what is afterwards found in the resulting sulphuric acid. But af'er the combustion of the sulphur, the nitre is converted into sulphate and bisul- phate 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 sulphu- ric acid is still to be sought for. The fol- lowing ingenious theory was first given by MM. Clement and Desormes. The burn- ing sulphur, or sulphurous acid, taking from the nitre a 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 AC1 ACI t'o the roof of the chamber ; and might be expected 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 nitrous gas comes in contact with atmospherical oxygen, nitrous acid vapour is formed, which being a very heavy aeriform body, immediately precipi- ^ates on the sulphurous flame, and con- vferts it into sulphuric acid ; while itself re- suming the state of nitrous gas, reascends for a new charge of oxygen, again to rede- scend, and transfer it, to the flaming sul- phur. Thus we see, that a small volume of nitrous vapour, by its alternate meta- morphoses into the states of oxide and acid, and its consequent interchanges, may be capable of acidifying a great quantity of sulphur. This beautiful theory received a modifi- cation from Sir H. Davy. He found that nitrous gas had no action on sulphurous gas, to convert it into sulphuric acid, un- less water be present. With a small pro- portion of water, 4 volumes of sulphurous acid gas, and 3 of nitrous gas, are conden- sed into a crystalline solid, which is instant- ly decomposed by abundance of water ; oil of vitriol is formed, and nitrous gas given off, which with contact of air becomes ni- trous acid gas, as above described. The process continues, according to the same principle of combination and decomposi- tion, 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. The proper mode of burning the sul- phur with the nitre, so as to produce the greatest quantity of oil of vitriol, is a prob- lem, concerning which chemists hold a va- riety of opinions. 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, fur- nished with an upright border, is placed horizontally over a furnace, whose chim- ney passes across, under the botton 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 de- scribed. When the combustion is finish- ed, which is seen through a little pane adapted to the trap -door of the chamber, Vo*. i. [14] this is opened, the sulphate of potash ik withdrawn, and is replaced by a mixture of sulphur and nitre. The air in the^great chamber is meanwhile renewed, by open- ing its lateral door, and a valve in its oppo- site side. Then, after closing these open- ings, the furnace is lighted anew. Succes- sive 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 stopcocks, and concentrated. The following details are extracted from a paper on sulphuric acid by Dr. Ure, which was 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 con- sist of sulphate of potash and lead, in the proportion of four of the former to one of the latter. It is, I believe, difficult to manu- facture it directly, by the usual methods, of a purer quality*. The ordinary acid sold in the shops contains often 3 or 4 per cent* of saline matter. Even more is occasion- ally introduced, by the employment of ni- tre, to remove the brown colour given to the acid by carbonaceous matter. The amount of these adulterations, whether accidental or fraudulent, may be readily determined by evaporating, in a small cap- sule of porcelain, or rather platinum, a de- finite weight of the acid. The platinum cup, placed on the red cinders of a com- mon fire, will give an exact result in five minutes If more than five grains of mat- ter 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 dif- ficult and hazardous ; but since adopting the following plan, I have found it perfect- ly safe and convenient. I take a plain glass retort, capable of holding from two to four quarts of water, and put into it about a pint measure of the sulphuric acid, (and a few fragments of glass,) connecti ng- the retort with a large globular receiver, by means of a glass tube 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 va- pour, rush forth from time to time, which would infallibly break small vessels. Here, however, these expansions are safely per- mitted, by the large capacity of the retort and receiver, as well as by the easy com- munication with the air at both ends of the ACI ACI adopter tube. Should the retort, indeed, be exposed to a great intensity of flame, the vapour will no doubt be generated with incoereible rapidity, and break the apparatus. But this accident can proceed only from gross imprudence. It resem- bles, in suddenness, the explosion of gun- powder, and illustrates admirably 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, 1 have ascertained that the specific caloric of the vapour of sulphuric 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 alco- hol and most other liquids are distilled. Indeed the application of cold to the bot- tom of the receiver generally causes it, in the present operation to crack. By the above method, I have made the concen- trated oil of vitriol flow over in a continu- ous slender stream, without the globe be- coming 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 concentrated, to exceed 1.8455. It is, I believe, more exactly 1.8452. The number 1.850, which it has been the fash- ion to assign for the density of pure oil of vitriol, is undoubtedly very erroneous, and ought to be corrected. Genuine commer- cial acid should never surpass 1.8485; when it is denser, we may infer sophistica- tion, or negligence, in the manufacture. 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 become 1.8417. We see that at these densities the addition of 0.01 of salt increases the specific gravity by about 0.0067. To the above 4140 grains other 80 grains of sulphate were added, and the specific gravity, after so- lution, was found to be 1.8526. W r e per- ceive that somewhat more salt is now re- quired 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 evaporated 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, - 91.4 100.0 Thus, acid of 1.8526, which in commerce would have been accounted very strong, contained little more than 91 per cent of genuine acid. Into the last acid more sulphate of pot- ash was introduced, and solution being fa- voured by digestion in a moderate heat, the specific gravity became, at 60, 1.9120. Of this compound, 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 den- sity and impurity may be stated at 0.0055 of the former, to 0.01 of the latter. If from genuine oil of vitriol, containing % of a per cent of saline matter, a consider- able 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 deposi- ted, after which its specific gravity be- comes 1.860, and its transparency is per- fect. It contains about 2 per cent of sa- line matter. Hence if the chemist em- ploy for nis researches an acid, which, though originally pretty genuine, has been exposed to long ebullition, 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 somewhat dilute. It is also evident, that those who trust to specific gravity alone, for ascer- taining the value of oil of vitriol, are liable to great impositions. The saline impregnation exercises an important influence, on all the densities at subsequent 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 genu- ine acid, as well as distilled acid, by the same degree of dilution, namely 1-f- 10, acquires the 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 commercial apparatus, Hence this mode ofascertain ACI ACI ing the value of an acid, recommended by Mr. Dalton, is inadequate to detect a deterioration 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 acidimeter one per cent of deterioration could not fail to be detected, even by those ignorant of science. The quantity of oxide, or rather sul- phate of lead, which sulphuric acid can take up, is much more limited than is commonly imagined. To the concentra- ted oil of vitriol I added much carbonate of lead, and after digestion 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 46. In the experiments executed, to de- termine the relation between the density of diluted oil of vitriol, and its acid strength, 1 employed a series of phials, numbered with a diamond. Into each phial, recently boiled acid, and pure water, were mixed in the successive pro- portions of 99 -f 1; 98 + 2; 97 + 3; &c. through the whole range of digits down to 1 acid -f- " water. The phials were occasionally agitated during 24 hours, after which the specific gravity 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 dis- tilled acid was employed for a few points, and gave the same results as the other. Of the three well known modes of as- certaining 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 ana of a delicate balance ; I decidedly prefer the last. The corrosiveness, vis- cidity, 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 con- centrated or slightly diluted acid, the temperature must be minutely regulated, because, from the small specific heat of the acid, it is easily afiected, 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, having its bulb covered with a film of dilute acid (from absorption of atmospheric moisture), be plunged into a strong acid, it will in- stantly rise 10, 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 experiments. 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 temperature rises, evincing* that it is a modification of cohesive at- traction. The following table of densities, corres- ponding to degrees of dilution, was the re- sult, in each point, of a particular experi- ment, and was, moreover, verified in a number of its terms, by the further dilu- tion of an acid, having previously com- bined with it a known proportion of water. The balance was accurate anil sensible. ACI ACI TABLE of the quantity of Oil of Vitriol and dry Sulphuric Acid in 100 parts of dilute, at different Densities, by Dr. UIIK. Liq. bp. Gr. Dry. Liq. 3p. Gr. Dry Uq. Sp.Gr. Dry. Liq. *p. Gr. Dry. 100 1.8485 81.54 75 1.6520 61.15 50 .3884 40.77 25 1.1792 20.38 99 1.8475 80.72 74 1.6415 60.34 49 .3788 39.95 24 1.1706 19.57 98 1.8460 79.90 73 1.6321 59.52 48 .3697 39.14 23 1.1626 18.75 97 1.8439 79.09 72 1.6204 58.71 47 .3612 38.32 22 1.1549 17.94 96 1.8410 78.28 71 1.6090 57.89 46 .3530 37.51 21 .1480 17.12 95 1.8376 77.46 70 1.5975 57.08 45 .3440 36.69 20 .1410 16.31 94 1.8336 76.65 69 1.5868 56.26 44 .3345 35.88 19 .1330 15.49 93 1.8290 75.83 68 1.5760 55.45 43 .3255 35.06 IS .1246 14.68 92 1.8-33 75.02 67 1.5648 *54.63 42 1.3165 34.^5 17 .1165 13.86 91 1,8179 74.20 66 1.5503 53.82 41 1.3080 33.43 16 .1090 13.05 90 1.8115 73.39 65 1.5390 5 : .00 i 40 1.2999 32.61 15 .1019 12.23 89 1.8043 72.57 64 1.5280 52.18 39 1.291., 31.80 14 .U953 11.41 88 1.7962 71.75 63 1.5170 51.37 38 1.2826 30.98 13 10.60 87 1.7870 7'<.94 62 1.5066 50.55 37 1.2740 30.17 13 .0809 9.78 86 1.7774 70.12 61 1.4960 49.74 36 1.2654 29.35 11 .0743 8.97 85 1.7673 69.31 60 1.4860 48.92 35 1.2572 28.54 10 .0682 8.15 84 1.7570 68.49 59 .4760 48.11 34 1.2490 27.72 9 .0614 7.34 83 1.7465 67.68 58 4660 47.29 33 1.2409 26.91 8 .0544 6.52 82 1.7360 66.86 57 .4560 46.48 3J 1.2334 26.09 7 1.0477 5.71 81 1.7 ,'45 66.05 56 .4460 45.66 31 1.2-260 25.28 6 1.0405 4.89 80 1.7120 65.23 55 .4360 44.85 30 1.2184 24.46 5 1.0336 4.08 79 1.6993 64.42 54 .4265 44.03 29 1.2108 23.65 4 1.0268 3.26 78 1.6870 63.60 53 .4170 43.22 28 1.2032 22.83 3 1.0206 2.446 77 1.6750 62.78 52 1.4073 42.40 27 1.1956 22.01 2 1.0140 1.63 76 1.6630 61.97 51 1.3977 41.58 26 1.1876 21.20 1 1.0074 0.8154 In order to compare the densities of the preceding 1 dilute acid, with those of dis- tilled and again concentrated acid, I mix- ed 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 indicates saline contamin- ation. Dilute acid having a specific gravity = 1.6321, has suffered the greatest con- densation ; 100 parts in bulk have become 92.14. If either more or less acid exist in the compound, the volume will be in- creased. What reason can be assigned for the maximum condensation occuring at this particular term of dilution ? 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 owe 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 symmetrical 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 there- fore produce less condensation. The very minute and patient examin- ation which 1 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, corres- ponding 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 numbers in in arithmetical progression, corresponding to another series, namely, the specific gravities in geometrical progression. The simplest logarithmic formula which 1 have been able to contrive is the follow- ing. 2a Log. S *= , where S is the specific 700 gravity, 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 spe- cific gravity. Multiply the logarithm of ACI ACI the specific gravity by 350, the product is directly the per centage of acid. If the dry acid be sought, we must mul- tiply the logarithm of the specific gravity by 285, and the product will be the an- swer. 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 lo- garithm 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. 100 95 90 85 80 75 Sp. Gr. 1.846 1.834 1.807 1.764 1.708 1.650 Dry Acid. 81.63 77.55 73.47 69.39 65.30 61.22* The sulphuric acid strongly attracts wa- ter, which it takes from the atmosphere very rapidly, and in larger quantities, if suffered to remain in an open vessel, im- bibing one-thi'-d 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 ther- mometer to 4 below 0. When pure it is colourless, and emits no fumes. It re- quires 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 1.78, or a few hundredths above or below this, it may be frozen by surrounding it with melting snow. Its congelation forms regular prismatic crystals Math six sides. Its boiling point, according to Bergmann, is 540 ; according to Dalton, 590. * Sulphuric acid consists of three prime equivalents of oxygen, one of sulphur, and one of water; and by weight, therefore, of 3.0 oxygen -f- 2.0 sulphur -j- 1.125 wa- ter = 6.125, which represents the prime equivalent of the concentrated liquid acid ; while 3 + 2 = 5, will be that of the dry acid. Pure sulphuric acid is without smell and colour, and of an oily consistence. Its ac- tion on litmus is so strong, that a single drop of acid will redden an immense quan- tity. 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 porcelain tube of one-fith of an inch dia- meter, it is resolved into two parts of sul- phurous acid gas, and one of oxygen gas, with water. Voltaic electricity causes an evolution of sulphur at the negative pole ; whilst a sulphate of the metallic wire is formed at the positive. Sulphuric 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 sul- phate of silver, there is immediately form- ed insoluble chloride of silver, and oxy- genized sulphuric acid. To obtain sul- phuric acid in the highest degree of oxy- genation, it is merely necessary to pour barytes-water into the above oxygenized 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. All the simple combustibles decompose sulphuric acid, with the assistance of heat. About 400 Fahr. sulphur, converts sul- phuric into sulphurous acid. Several me- tals at an elevated temperature decompose this acid, with evolution of sulphurous acid gas, oxidizement of the metal, and combination of the oxide, with the unde- composed portion of the acid.* The sulphuric acid is of very extensive use in the art of chemistry, as well as in metallurgy, bleaching, and some of the processes for dyeing; in medicine it is given as atonic, stimulant, and lithontrip- tic, and 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, in coarse powder, rounded masses, sta- lactites, and regular crystallizations, which are in some lamellar, in others needly, in others prismatic or pyramidal. The cawks of our country and the Bologiiian stone are merely native sulphates of barytes. Their colour varies considerably as well as their figure, but their specific gravity is great, that of a very impure kind being 3.89, and the pure sorts varying from 4 to 4.865 ; hence it has been distinguished by the names of marmor metallicum and pon- derous spar. * It consists, according to Dr. Wollas- ton, of 5 parts of dry acid, and 9.75 of barytes ; and by Professor Berzelius's last estimate, of 5 of acid and 9.573 barytes.* This salt, though deleterious, is less so than the carbonate of barytes, and is more economical for preparing the muriate for medicinal purposes. It requires 43.000 parts of water to dissolve it at 60. Sulphate of strontian has a considerable ACI ACI resemblance to that of barytes in its pro- perties. It is found native in considerable quantities at Aust Passage and other places in the neighbourhood of Bristol. It requires 3840 parts of boiling water to dissolve it. * Its composition is 5 acid -j- 6.5 base.* The sulphate of potash, vitriolated kali of the London college, formerly vitriolated tartar, sal de duobns, and arcanum duplica- turn, crystallizes in hexaedral prisms, terminated by hexagonal pyramids, but susceptible of variations. Its crystalliza- tion 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 decrepi- tates, and is fusible by a strong heat. It is decomposable by charcoal at a high temperature. It may be prepared by di- rect mixture of its component parts ; but the usual and cheapest mode is to neutral- ize the acidulous sulphate left after distill- ing nitric acid, the sal enixum of the old che- mists, by the addition of carbonate of pot- ash. The sal poly chrest of old dispensatories, made by deflagrating sulphur and nitre in a crucible, was a compound of the sulphate and sulphite of potash. The acidulous sul- phate is sometimes employed as a flux, and likewise in the manufacture of alum. In medicine the neutral salt is sometimes used as a deobstruent, and in large doses as a mild cathartic ; dissolves in a consid- erable portion of water, and taken daily in such quantity as to be gently aperient, it has been found serviceable in cutaneous affections, and is sold in London for this purpose as a nostrum ; and certainly it de- serves to be distinguished from the gene- rality of quack medicines, very few indeed of which can be taken without imminent hazard. * It consists of 5 acid+ 5.95 base; but there is a .compound of the same constitu- ents, in the proportion of 10 acid -j- 5.95 potash, called the bisulphate.* The sulphate of soda is the -vitriolated natron of the col'ege, the well known Glauber's salt, or sal mirabile. It is com- monly prepared from the residuum left after distilling muriatic acid, the superflu- ous acid of which may be saturated by the addition of soda, or precipitated by lime ; and is likewise obtained in the manufac- ture of the muriate of ammonia. (See AM- MONIA). Scherer mentions another mode by Mr. Funcke, which is, making 8 parts of calcined sulphate of lime, 5 of clay, and 5 of common salt, into a paste with water ; burning this in a kiln; and then powder- ing, lixiviating, and crystallizing. It exists in large quantities under the sin-face of the earth in some countries, as Persia, Bohe- mia, and Switzerland ; is found mixed with other substances in mineral springs and sea water ; and sometimes effloresces on walls. 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 longitudinally, and of very large size, when the quantity is great : these effloresce completely into a white pow- der if exposed to a dry air, or even if kept wrapped up in paper in a dry place ; yet they retain sufficient water of crystalliza- tion to undergo the aqueous fusion on ex- posure 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 decompo- sed. As a purgative its use is very gene- ral ; 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 -f 3.95 base -f- 11.25 water in crystals ; when dry, the former two primes are its constituents.* Sulphate of soda and sulphate of am- monia form together a triple salt. Sulphate of lime, selenite, gypsum, plas- ter of Paris, or sometimes alabaster, forms extensive strata in various mountains. The specular gypsum, GY glades Marine, is a spe- cies of this salt, and affirmed by some French travellers to be employed in Rus- sia> where it abounds, as a substitute for glass in windows. Its specific gravity is from 1.872 to 2.311. It requires 500 parts of cold water, and 450 of hot, to dissolve it. When calcined it decrepitates, 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. In this state it is found na- tive in Tyrol, crystallized in rectangular parallelepipeds, or octaedral or hexaedral prisms, and is called anhydrous sulphate of lime. Both the natural and artificial anhy- drous sulphate consists of 56.3 lime and 43.6 acid, according to Mr. Chenevix. The calcined sulphate is much employed for making casts of anatomical and orna- mental figures; as one of the bases of stucco ; as a fine cement for making close and strong joints between stone, and join- ing rims or tops of metal to glass ; for making moulds for the Staffordshire pot- teries ; for cornices, mouldings, and other ornaments in building. For these purpo- ses, and for being wrought into columns, chimney-pieces, and various ornaments, about eight hundred tons are raised annu- AC1 ACI ally in Derbyshire, where it i& called ala- baster. In America it is laid on grass land as a manure. * Ordinary crystallized gypsum consists of 5 sulphuric acid -\- 3.6 lime -f- 2.25 wa- ter ; the anhydrous variety wants of course the last ingredient.* Sulphate of magnesia, the vitriolated magnesia of the late, and sal catharticus umarus of former London Pharmacopoeias, is commonly known by the name of Epsom aalt t as it was furnished in considerable quantity by the mineral water at that place, mixed however with a considerable por- tion of sulphate of soda. It is afforded, however, in great abundance and more pure from the bittern left after the extrac- tion of salt from sea water. It has likewise been found efflorescing on brick walls, both old and recently erected, and in small quantity in the ashes ot coals. The capil- lary salt of Idria, found in silvery crystals mixed with the aluminous schist in the mines of that place, and hitherto consider- ed as a feathery alum, has been ascertain- ed 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 diiidral sum- mits. 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. Exposed to heat, it dissolves in its own water of crystallization, and dries, but is not de- composed, nor fused, but with extreme difficulty. It consists, according to Berg- mann, of 33 acid, 19 magnesia, 48 water. A very pure sulphate is said to be prepar- ed in the neighbourhood of Genoa by roasting a pyrites found there ; exposing it to the air in a covered place for six 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 car- bonate of magnesia. * It is composed of 5 acid -j- 2. 5 magne- sia + 7-875 water, in the state of crystals.* Sulphate of ammonia crystallizes in slen- der, flattened, hexaedral prisms, termi- nated by hexagonal pyramids ; it attracts a little moisture from very damp air, par- ticularly if the acid be in excess ; it dis- solves in two parts of cold and one of boil- ing water, [t is not used, though Glauber, who called it his secret ammoniacal salt, vaunted its excellence in assaying. * It consists of 5 acid + 2.17 ammonia -f- 1.125 water in its most desiccated state ; and in its crystalline state of 5 acid -f- 2.13 ammonia -|- 3.375 water.* If sulphate of ammonia and sulphate of magnesia be added together in solution, they combine into a triple salt of an octae- dral figure, but varying much ; less solu- ble 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 contains, according to Fourcroy, 68 sulphate of magnesia, and 32 sulphate of ammonia. Sulphate of glucina crystallizes with difficulty, its solution readily acquiring and retaining a sirupy consistence ; its taste is sweet, and slightly astringent ; it is not alterable in the air ; a strong heat expels its acid, and leaves the earth pure ; heated with charcoal 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 alight amethyst 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 atten- tively 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, dry- ing the residuum with a pretty strong heat^ redissolving it, and crystallizing. Its crys- tals are soft, foliaceous, shining, and pear- ly ; but these are not easily obtained with- out cautious evaporation and refrigeration. They have an astringent taste ; are little alterable in the air ; are pretty soluble > particularly in hot water ; give out their acid on exposure to a high temperature ; are decomposable by combustible substan- ces, though not readily ; and do not form a pyrophorus like alum. If the evaporation and desiccation di- rected above be omitted, the alumina will remain supersaturated with acid, as may- be known by its taste, and by its redden- ing vegetable blue. This is still more dif- ficult to crystallize 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 ACI ACI white powder. This salt is completely in- soluble, 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 slow!}'. Sulphate of zircon may be prepared by adding sulphuric acid to the earth recent- ly precipitated, and not yet dry. It is sometimes in small needles, but common- ly pulverulent ; very friable; insipid; in- soluble in \vater, unless it contain some acid; and easily decomposed by heat. ACID (StJLPHtrnors.) It has already h,een observed, that sulphur burned at a low temperature absorbs less oxygen than it does when exposed to greater heat, and is consequently acidified in a slighter de- gree, so as to form sulphurous acid. This in the ordinary state of the atmosphere is a gas ; but on reducing its temperature very low by artificial cold, and exposing it to strong compression, it becomes a li- quid. To obtain it in the liquid state, however, for practical purposes, it is re- ceived into water, by which it is absorbed. As the acid obtained by burning sulphur in this way is commonly mixed with more cr less sulphuric acid, when sulphurous acid is wanted, it is commonly made by ab- stracting part of the oxygen from sulphu- ric acicl by means of some combustible substance. Mercury or tin is usually pre- ferred. For the purposes of manufactures, however, chopped straw or saw-dust may be employed. If one part of mercury and two of concentrated sulphuric acid be put into a glass retort with a long neck, and heat applied till an effervescence is pro- duced, the sulphurous acid will arise in the form of gas, and may be collected over quicksilver, or received into water, which at the temperature 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 burning slowly. It destroys most vegcta- fcle colours, but the blues are reddened by it previous to their being discharged. A pleasing instance of its effect on colours may be exhibited by holding a red rose ever the blue flame of a common match, by which the colour will be discha)-ged wherever the sulphurous acid comes into contact with it, so as to render it beautiful- ly variegated, or entirely 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. Thenard and Gay- Lussac, is 2.2553, but by Sir H. Davy "is 2.2295, and hence 100 cubic inches weigh 68 grains ; but its sp. gr. most probably should be estimated at 2-.222, and the weight of 100 cubic inches will become 67.777. Its constituents by volume are one of oxygen, and one of vapour of sul- phur; each having a sp. gr. of 1.111, con- densed so that both volumes occupy onl> one. Or in popular language, sulphurous acid may be said to be a solution of sul- phur 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 = 4 ; or 1 oxygen -f- 1 sulphur = 2. Now the analysis of sulphite of ba- rytes by Berzelius gives 209.22 base to 86.53 acid; which being reduced, presents for the prime equivalent of sulphurous acid, the number 4. Hydrogen and car- bon readily decompose sulphurous acid at a red heat, and even under it. Mr. Hig- gins discovered, that liquid sulphurous acid dissolves iron, without the evolution of any gas The peroxides of lead and manganese furnish oxygen to convert it into sulphuric acid, which forms a sul- phate, with the resulting metallic protox- ide.* Sulphurous acid is used in bleaching, particularly for silks. It likewise dischar- ges vegetable stains, and iron-moulds from linen. In combination with the salifiable bases, it forms sulphites, which differ from the sulphates in their properties The alka- line sulphites are more soluble than the sulphates, the earthy less. They are con- verted into sulphates by an addition of oxygen, which they acquire even by ex- posure to the air. The sulphite of lime is the slowest to undergo this change. A strong heat either expels their acid entire- ly, or converts them into sulphates. They have all a sharp, disagreeable, sulphurous taste. The best mode of obtaining them is by receiving the sulphurous acid gas in- to water, holding the base, or its carbo- nate, in solution, or diffused in it in fine powder. None of them has yet been ap- plied to any use. * ACID (Hvposui.nirnovs.) In the 85th volume of the Annales de Chimie, M. Gay- Lussac describes permanent crystalhzable 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 se- parate state. Those salts were procured by exposing solutions of the sulphurets of the earths to the air, when sulphur and carbonate of lime precipitated. When the filtered liquid is then evaporated, and cool- ed, colourless crystals form. The calca- reous are prismatic needles, and those with strontites are rhomboidal. He called tliese new compounds sulphuretted sui- AC1 ACI . Those of potash and soda he also formed, by heating their sulphites with sulphur ; when, a quantity of sulphurous acid was disengaged, and neutral salts were formed. M. Gay-Lussac farther in- forms us, that boiling a solution of a sul- phite with sulphur, determines the forma- tion of the sulphuretted sulphite, or hy- posulphite ; and that iron, zinc, and man- ganese, treated with liquid sulphurous 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 hyposul- phites are more permanent than the sul- phites ; they do not readily pass by the action of the air into the state of sulphate; and though decomposable at a high heat, they resist the action of fire longer than the sulphites. They are decomposed in solution by the sulphuric, muriatic, fluo- ric, phosphoric, and arsenic acids; sulphu- ipus acid is evolved, sulphur is precipita- ted, 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, publish- 6d in 1814. No additional information was communi- fcated to the world on this subject till Jan- uary 1819, when an ingenious paper on the hyposulphites appeared in the Edin- burgh Philosophical 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 niters. The first was received into a solution of carbo- nate of potash, from which it expelled car- bonic acid gas. The second portion be- ing received successively into nitrates of Silver and mercury, precipitated the me- tals copiously in the state of sulphurets, but produced no effect on solutions of cop- per, iron, or zinc. The third, being tasted, was acid, astringent and bitter. When fresh filtered it was clear, but it became milky on standing, depositing sulphur, and colouring sulphurous acid. A moderate exposure to air, or a gentle heat, caused its entire decomposition, r The habitudes of oxide of silver in union with this acid are very peculiar. Hyposul- phite of soda being poured on newly pre- cipitated oxide of silver, hyposulphite of silver was formed, and caustic soda elimi- nated ; the only instance, says Mr. Her- schel, yet known of the direct displace- ment of a fixed alkali by a metallic oxide, via hwnida. On the other hand, hyposul- nhurous acid newly disengaged from the Vot. r. [ 15 } hyposulphite of barytes, by dilute sulphu- ric acid, readily dissolved, and decompos- ed muriate of s'ilver, 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 by any double decomposition, is such as to form an exception to all the or- dinary rules of chemical union." This acid has a remarkable tendency to form double salts with the oxides of silver and alkaline bases. The hyposulphite of sil- ver 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 blot- ting paper and dried in vacua. It is very soluble in water. Its sweetness is unmix- ed with any other flavour, and so intense as to cause pain in the throat. One grain of the salt communicates a perceptible sweetness to 32.000 grains of water. If the alcoholic liquid be evaporated, thin lengthened hexangular plates are some- times formed, which are not altered by keeping, and consist of the same princi- ples. The best way of obtaining the alkaline hyposulphites is to pass a current of sul^ phurous acid gas through a lixiviwn, form- ed by boiling a watery solution of alkali, or alkaline earth, along with sulphur. The whole of the sulphurous acid is converted into the hyposulphite, and pure sulphur, unmixed with any sulphite, is precipitat- ed, while the hyposulphite remains in so- lution. Mr. Herschel, from his experiments on the hyposulphite of lime, has deduced the prime equivalent of hyposulphurous acid, to be 5.925. He found that 100 parts crystallized hyposulphite of lime, were; equivalent to 121.77 hyposulphite of lead, and yielded of carbonate of lime, by car- bonate of ammonia, a quantity equivalent to 21.75 gr. of lime. Therefore the theo- ry of equivalent ratios gives us this rule : As 21.75 gr. lime are to its prime equi- valent 3.56, so are 121.77 gr. of hyposu^- phite of lead, to its prime equivalent. In numbers 21.75 : 3.56 : : 121.77 : 19.93. From this number, if we deduct the prime of the oxide of lead = 14, the remainder 5.93 will be the double prime of hyposul- phurous 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 propor- tion of it is obviously made up of 1 prime of sulphur = 2, -{- 1 oxygen = 1 ; and the acid equivalent is =* 3. The crystallized hyposulphite of lime is composed of 6. acid -f- 3.56 lime -f- 6.75 water, being 6 primes of the last constituent, ACI ACI It ought to be stated, that when a solu- tion of a hyposulphite is boiled down to a certain degree of concentration, it be- gins 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 filter- ed while hot, it will yield on cooling, large and exceedingly beautiful crystals, which assume a great variety of complicated forms. They are soluble in nearly their own wreight of water at 37 Fahr. and the temperature of the solution falls to 31. The specific gravity of their saturated so- lution 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 deliquescent crystals of a bitter taste, and both of them dissolve muriate of silver. The ammoniacal alt is not easily procured in regular crystals. Its taste is pungent and disagreeable. The barytic hyposul- phite is insoluble ; the strontitic is soluble ^nd crystallizable. Like the other hypo- sulphites it dissolves silver ; and while its own taste is purely bitter, it produces a sweet compound with muriate of silver, which alcohol throws down in a sirupy ibrm. Hyposulphite of magnesia is a bit- ter tasted, soluble, crystallizable, and non- deliquescent salt. All the hyposulphites burn with a sulphurous flame. The sweet- ness of liquid hyposulphite of soda, com- bined with muriate of silver, surpasses honey in intensity, diffusing itself over the ^whole mouth and fauces without any disa- greeable or metallic flavour. A coil of zinc wire speedily separates the silver in a metallic state, thus affording a ready analysis of muriate of silver. Muriate of lead is also soluble in the hyposulphites, but less readily.* * Acid (HYPOSULPHURIC). MM. Gay- Lussac and Welther have recently an- nounced the discovery of a new acid com- bination of sulphur and oxygen, interme- diate between 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 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 ex- cess of barytes by a current of carbonic acid, crystallizes regularly, like the nitrate or muriate of barytes. Hyposulphate of barytes being thus obtained, sulphuric acid is cautiously added to the solution, \vhich throws down the barytes, and leaves the hyposulphuric acid in the water. This acid bears considerable concentration un- der the receiver of the air-pump. It con- sists of five parts of oxygen to four of sul- phur. The greater number of the hypo- sulphates, both earthy and metallic are so- luble and crystallize ; those of barytes and lime are unalterable in the air. Suberic acid and chlorine do not decompose the barytic salt The barytic salt in crystals, consists of barytes 9.7 + hyposulphuric acid 9.00 -f water 2.25 = 20,95. The following table exhibits the com- position of the different acid compounds of sulphur and oxygen : Hyposulphurous acid 20 sul. -f- 10 oxygen Sulphurous acid 10 -j- 10 Hyposulphuric acid 8 -j- 10 Sulphuric acid 2| -f- 10 Or if we prefer to consider the quantity of sulphur in each acid as = 2, the oxygen combines with it in the following propor- tions : 1 ; 2 ; 2.5 ; 3. Hyposulphuric acid is distinguished by the following properties : 1st, It is decomposed by heat into sul- phurous and sulphuric acids. 2(1, It forms soluble salts with barytes^ strontites, lime, lead, and silver. 3d, The hyposulphates are all soluble. 4t/i, They yield sulphurous acid whe* 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 deserves to be mentioned, that Dr. Gules of Paris, has, by means of a chest or case, called Boete Fumigatoire, applied the va- pour of burning sulphur, or sulphurous acid gas, mixed with air, to the surface of the body, as an air bath, with great advan- tage, in many chronic diseases of the skin, the joints, the glands, and the lymphatic system.* 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 tar- tar, and distinguished into red and white according to its colour. This being puri- fied by solution, filtration, and crystalliza- tion, was termed cream or crystals of tartar,. It was afterwards discovered, that it con- sisted of a peculiar acid combined witk potash ; and the supposition that it was formed during the fermentation of the wine, was disproved by Boerhaave, Neu- mann, and others, who showed that it ex- isted ready formed in the juice of the grape. It has likewise been found in other fruits, particularly before tlxey are too ACI AC1 3 hydrogen 4 carbon 5 oxygen ripe ; aftd in the tamarind, sumac, balm, the acid prime equivalent ; and it may be carduus benedictus, and the roots of rest- made up of harrow, germander, and sage. The sepa- ration of tartaric acid from this acidulous salt, is the first discovery of Scheele that is known. He saturated tht superfluous acid by adding chalk to a solution of the supertartrate in boiling water as long as any effervescence ensued, and expelled The crystallized acid is a compound of the acid from the precipitated tartrate of 8.375 acid + 1.125 water = 9.5 ; or in 100 lime by means of the sulphuric. Or four parts 88.15 acid + 11.85 water, parts of tartar may be boiled in twenty or The tartrates in their decomposition by twenty -four of water, and one part of sul- fire, comport themselves like all the other phuric acid added gradually. By continu- vegetable salts, except that those with ex- .1 1 f iL 1 I. A. 1* A. 1> '11 L f * J 1 J J.T- 11 J? 71- = 0.3 75 4.48- = 3.000 35.82 = 5.000 59.70 8.375 100.00 ing the boiling the sulphate of potash will fall down. When the liquor is reduced to cess of acid yield the smell ofcaromel when heated, and afford a certain quantity of one-half, it is to be filtered, and if any more the pyro tartaric acid. All the soluble neu- sulphate be deposited by continuing the boiling 1 , the filtering must be repeated. When no more is thrown down, the liquor is to be evaporated to the consistence of a sirup, and thus crystals of tartaric acid, equal to half the weight of the tartar em- ployed, will be obtained. The tartaric acid may be procured in tral tartrates form with tartaric acid, bitar- trates of sparing solubility ; while all the insoluble tartrates may be dissolved in an excess of their acid. Hence, by pouring gradually an excess of acid into barytes, strontites and lime-waters, the precipitates formed at first cannot fail to disappear ; while those obtained by an excess of the needly or laminated crystals, by evaporat- same acid, added to concentrated solutions ing a solution of it. Its taste is very acid and agreeable, so that it may supply the place of lemon-juice. It is very soluble in water. Burnt in an open fire, it leaves a of potash, soda, or ammonia, and the neu- tral tartrates of these bases, as well as of magnesia and copper, must be permanent. The first are alwavs flocculent ; the se- coaly residuum; in close vessels it gives cond always crystalline; that of copper out carbonic acid and carburetted hydro- gen 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 redundant acid with chalk, to add mu- riate of lime to the supernatant neutral tartrate, by which means it is completely decomposed. The insoluble tartrate of lime being washed with abundance of wa- % ter, is then to be treated with three-fifths of its weight of strong sulphuric acid, di- luted previously with five parts of water. But Fourcroy's process as improved by Vauquelin, seems still better. Tartar is treated with quicklime and boiling water in the proportion, by the theory of equi- valents, 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 + 35.980 carbon + 60.213 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 omitted to estimate. The Analysis of tartrate of lead, gives 8.384 for 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, because they transform these salts into bitartrates ; and on the contrary, they ought to effect the solution of the neutral insoluble tar- trates, which indeed always happens, un- less the acid cannot dissolve the base of the tartrate. The order of apparent affi- nities of tartaric acid are, lime, barytes, strontites, potash, soda, ammonia, and magnesia. The tartrates of potash, soda, and am- monia, are not only susceptible of combin- ing together, but also with the other tar^ trates, so as to form double or triple salts, We may thus easily conceive why the tar- trates of potash, soda, and ammonia, do not disturb the solutions of iron and man- ganese ; 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 ex- cess.* The tartrates of lime and barytes are white, pulverulent, and insoluble. Tartrate of strontian, formed by the double decomposition of muriate of stron- tian and tartrate of potash, according to Vauquelin, is soluble, crystallizable, and consists of 52.88 etrontian and 47.12 acid. ACI ACI That of magnesia forms a gelatinous or gummy mass. Tartrate of potash, the tartarized kali of the London college, and -vegetable salt of some, formerly called soluble tartar, be- cause much more so than the supertar- trate, crystallizes in oblong squares, be- velled at the extremities. It has a bitterish taste, and is decomposed by heat, as its so- lution is even by standing some time. It is used as a mild purgative. The supertartrate of potash, already mentioned at the beginning of this article, is much used as a cooling and gently open- ing medicine, as well as in several c^iemi- cal and pharmaceutical preparations. Dis- solved in water, with the addition of a lit- tle sugar, and a slice or two of lemon- peel, it forms an agreeable cooling drink by the name of imperial,- and if an infu- sion of green balm be used instead of wa- ter, it makes one of the pleasantest liquors of the kind with which we are acquainted. Mixed with an equal weight of nitre, and projected into a red-hot crucible, it deto- nates, and forms the ivhite flux / treated in the same way with half its weight of nitre, it forms the black jftuac , and simply mixed with nitre in various proportions, it is called raw jlux. 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 ^ ff of pipe clay. According to the analysis of Berzelius, it consists of 70.45 acid -f 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 60 parts of water dissolve 4 of bitartrate at a boiling heat; and only 1 at 60 Fahr. It is quite imsoluble 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 bitar- trate, in containing no water qf crystalli- zation. 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 equiva- lent proportions. On considering the great solvent pro- perty of cream of tartar, and that it is even capable of dissolving various oxides, which are insoluble in tartaric acid, as the pro- toxide of antimony, M. Gay-Lussac has recommended it as a useful agent in che- mical analysis. He thinks that in many sases it acts the part of a single acid, Ac- cording to this view, tartar emetic would be a compound of the cream-tartar acid, and protoxide of antimony. Cream of tar- tar generally contains from 3 to 5 per cent of tartrate of lime, which are in a great measure separated when 3 parts of tartar are boiled with 1 of borax for a few mi- nutes in a sufficient quantity of water. The soluble cream of tartar which is ob- tained by this process is deliquescent ; it dissolves in its own weight of water at 54.5, and in half its weight of boiling water. Its solution is very imperfectly decomposed by the sulphuric, nitric, and muriatic acids. 4 parts of tartar and 1 of boracic acid form a permanent saline com- pound, very soluble in water. Alum also increases the solubility of tartar.* By saturating the superfluous acid in this supertartrate with soda, a triple saltisform- ed, which crystallizes in large regular prisms of eight nearly equal sides, of a bitter taste, efflorescent, and soluble in about five parts of water. It consists, according to Vauquelin, of 54 parts tartrate of pot- ash and 46 tartrate of soda, and was once in much repute as a purgative, by the name of Rochelle salt, or set de Seignette. The tartrate of soda is much less solu- ble than this triple salt, and crystallizes in slender needles or thin plates. The tartrate of ammonia is a very solu- ble, 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 efflo- rescent crystals. Though both the neutral salts that compose it are bitter, this is not, but has a cooling taste. ACID (TUNGSTOUS). What has been thus called appears to be an oxide of TCXGSTEIT. * 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 follow- ing way. The wolfram cleared from its si- liceous gangue, and pulverized, is heated in a matrass \\ ith five or six times its weight of muriatic acid, for half an hour. The ox- ides of iron and manganese being thus dis- solved, we obtain the tungstic acid under the form of a yellow powder. After wash- ing it repeatedly with water, it is then di- gested 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 be- ing ignited, the ammonia flies off, and pure tungstic acid remains. If the whole of the wolfram has not been decomposed in this operation, it must be subjected to the muriatic acid ag-ajn, ACI ACT It is tasteless, and does not affect vege- table colours. The tungstates of the alka- lis and magnesia are soluble and crystalli- zable, the other earthy ones are insoluble, as well as those of the metallic oxides. The acid is composed of 100 parts metal- lie tungsten, and 25 or ^6.4 oxygen.* ACID (URIC). The same with LITHIC ACID ; which see. ACID (Zooxic). In the liquid procured by distillation from animal substances, winch had been supposed to contain only carbonate of ammonia and an oil, Berthol- let imagined 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 an animal matter. * ACID (ZUMIC). An acid called by M. Braconnot, Nanceic, in honour of the town of Nancy, where he lives. He discovered it in many acescent vegetable substances ; in sour rice ; in putrefied juice of beet- root ; in sour decoction of carrots, peas, &c. He imagines that this acid is genera- ted at the same time as vinegar in organic substances, when they become sour. It is without colour, does not crystallize, and has a very acid taste. He concentrates the soured juice of the beet-root till it become almost solid, digests it with alcohol, and evaporates the alcoholic solution to the consistence of sirup. He dilutes this with water, and throws into it carbonate of zinc till it be saturated. He passes the liquid through a filter, and evaporates till a pellicle ap- pear. The combination of the new acid with oxide of zinc crystallizes. After a second crystallization, he dissolves it in water, pours in an excess of water of barytes, decomposes by sulphuric acid the bary tic salt formed, separates the deposite by a filter, and obtains, by evaporation, the new acid, pure. It forms with alumina a salt resembling gum, and with magnesia one unalterable in the air, in little granular crystals, soluble in 25 parts of water at 66 Fahr ; with potash and soda it forms uncrystal- lizable salts, deliquescent and soluble in alcohol ; with lime and strontites, soluble granular salts ; with barytes, an uncrystal- lizable nondeliquescent salt having the aspect of gum; with white oxide of manganese, a salt which crystallizes in tetrahedral prisms, soluble in 12 parts of water at 60 ; with oxide of zinc, a salt crystallizing in square prisms, terminated by summits obliquely truncated,! soluble in 50 parts of water at 66 ; with iron, a salt crystallizing in slender four-sided needles, of sparing solubility and not changing in the air; with red oxide of iron, a white nonerystallizing salt; with oxide of tin, a salt crystallizing in wedge- form octahedrons ; with oxide of lead an uncrystallizable salt, not deliquescent, and resembling a gum ; with black oxide of mercury, a very soluble salt, which crystallizes in needles.* ACIDIFIABLE. Capable of being con- verted into an acid by an acidifyng prin- ciple. (See ACID). Substances posses- sing this property are called radicals, or acidijlable bases. ACIDUIE. 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 proper- ties ; such as the supertartrate of potash. * ACOWITA. A poisonous vegetable principle, probably alkaline, recently ex- tracted from the Jlconitum napelhis, or Wolfsbane, by M. Brandes. The details of the analysis have not reached this country.* * ACTIWOLITE, Strahlstein of Werner. Jbnphibole Jlctinote hexaedre fof Hauy. There are three varieties of this mineral : the crystallized, the asbestous, and the glassy. Isty Crystallized actinolite. Colour leek green, and green of darker shades. It crystallizes in long oblique hexahedra! prisms with irregular terminations. Crys- tals frequently striated lengthwise, some- times acicular. 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 indistinct twofold cleavage. It scratches glass. 2d, Asbestous actinolite. Colours green, verging on gray and brown, and smalt, blue. Massive and in elastic capillary crystals, which are grouped in wedge- shaped, radiated or promiscuous masses. Internal lustre pearly. Melts before the blow-pipe into a dark glass. Fracture intermediate between fibrous and nar- row radiated. Fragments wedge-shaped. Opaque. Soft. Tough but sectile. Sp. gr. 2.7 to 2.9. 3d, Glassy actinelite. Colours, mountain green, and emerald green. In thin six sided needle-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 actinolite are the folr lowing, 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 maganese 0.5, oxide of chromium 3, potash 0.5, moisture 5, loss 0.25. 28.2. of alumina and 3. 84 oftungstic acid were found in 100 parts of asbestous actinolite from Cornwall, analyzed by Dr. Thomson. Actinolite is found chiefly in primitive districts, with a magnesian basis. It ADA ADI Accompanies talc, and some micaceous rocks. Its principal localities are Ziller- thal, in the Tyrol ; Mont St. Gothard ; near Saltzburg, in Saxony ; in Norway 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. ADAMANTINE SPAR. This stone, which comes to us from the peninsula of Hither India, and also from China, has not en- gaged the attention of the chemical world till within a few years past. It is remark- able for its extreme hardness, whi$h ap- proaches to that of the diamond, and by virtue of which property it is used for polishing gems. Two varieties of this stone are known in Europe. The first comes from China. It is crystallized, in six-sided prisms, with- out pyramids, the length of which varies from half an inch to an inch, and their thickness is about three quarters of an inch. Its colour is gray of different shades. The larger pieces are opaque ; but thin pieces and the edges of the prisms are transparent. Its fracture is brilliant, and its texture spathose ; which causes its surface to appear lightly striated. Its crystals are covered with a very fine and Strongly adherent crust of plates of silvery mica, mixed with particles of red feldspar. A yellow superficial covering of sulphate f iron was observed upon one speci- men. This stone is so hard that it not only cuts glass as easily as a diamond, but like- wise marks rock crystal and several other hard stones. Its specific gravity is 3.7*0. Small crystalline grains of magnetical ferruginous calx are occasionally found in the adamantine spar of China, which may be separated by the magnet when the stone is pulverized. The second variety, which comes from India, is called Corundum by the inhabi- tants of Bombay. It differs from the for- mer by a white colour, a texture more evi- dently spathose, and lastly, because the grains of magnetical iron are smaller than in the former specimens, and are not in- terspersed through its substance, but only at its surface. From its hardness it is extremely diffi- cult to analyze. M. Chenevix,by repeat- edly heating it red hot, and then plunging it into cold water, caused it to appear fis- sured in every direction. He then put it into a steel mortar, about three quarters of an inch in diameter, and three inches deep, to which a steel pestle was closely fitted. A few blows on the pestle caused it to crumble, and the fragments were then easily reduced to an impalpable powder by an agate pestle and mortar. This pow- der was fused in a crucible of platinum with twice its weight of calcined borax, and the glass was dissolved by boiling in muriatic acid about twelve hours. The precipitates from this solution being ex- amined, a specimen from China was found to give from 100 parts, 86.50 of alumina, 5.25 of silex, 6.50 of iron : one from Ava, alumina 87, silex 6.5, iron 4.5 : one from Malabar, alumina 86.5, silex 7, iron 4 : one from the Carnatic, alumina 91, silex 5, iron 1.5. The Rev. Mr. W. Gregor analyzed a specimen from Thibet, in the collection of Mr. Rashleigh, which gave him alumina 81.75, silex 12.125, oxide of titanium 4, water 0.937, but no iron. This stone has been said to have been found in different parts of Europe, and near Philadelphia in America ; but most, if not all of the specimens have proved not to be the adamantine spar. Lately, how- ever, Prof. Pini has discovered a stone in Italy, the characters of which, as given by him, agree with those of the adamantine spar. See CORUNDUM. ADHESION. See COHESION. * ADHESIVE SLATE. See SLATE.* ADIPOCERE. The attention of chemists has been much excited by the spontaneous conversion of animal matter into a sub- stance considerably resembling spermace- ti. 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 may be called the scientific dis- coverer of this peculiar matter, as well as the saponaceous ammoniacal substance contained in bodies abandoned to sponta- neous destruction in large masses. This chemist read a memoir on the subject in the year 1789 to the Royal Academy of Sciences, from which 1 shall abstract the general contents. At the time of clearing the before men- tioned burying-place, certain philosophers were specially charged to direct the pre- cautions requisite for securing the health of the workmen. A new and singular ob- ject of research presented itself, which had been necessarily unknown to prece- ding chemists. It was impossible to fore- tell 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 surrounded by a portion of the soil. It was the burying-ground of a large district, wherein successive generations of the in- habitants had been deposited for upwards of three centuries. It could not be fore- seen that the entire decomposition might ADI ADI fce retarded for more than forty ye*afs; neither was there any reason to suspect that any remarkable difference would arise from the singularity of situation. The remains of the human bodies im- mersed 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, brittle, hard, more or less gray, and similar to what are called mummies in cer- tain caverns where this change has been observed, as in the catacombs at Rome, and the vault of the Cordeliers at Tou- louse. The third and most singular state of these soft parts was observed in the bodies which filled the common graves or repo- sitories. By this appellation are under- Stood caviiies of thirty feet in depth and twenty on each side, which were dug in flie bury ing-ground of the Innocents, and were appropriated to contain the bodies of the poor; which were placed in 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 consi- dered when filled as an entire mass of hu- man bodies, separated only by two planks of about half an inch thick. Each cavity contained between one thousand and fif- teen 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 required to fill it. Accord- Ing to the urgency of circumstances, the graves were again made on the same spot after an interval of time not less than fif- teen years, nor more than thirty. Expe- rience had taught the workmen, that this time was not sufficient for the entire de- struction of the bodies, and had shown them the progressive changes which form the object of Mr. 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 preservation, but a little settled, and the wood (I suppose deal) had a yel- low tinge. When the covers of several were taken off, the bodies were observed at the bottom, leaving a considerable dis- tance between their surface and the cover, and flattened as if they h$d suffered a strong compression. The linen which had covered them was slightly adherent to the bodies ; and, with the form of the differ- ent regions, exhibited, on removing the linen, nothing but irregular masses of a soft ductile matter of a gray 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 common 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 sin- gularity 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 grtu (fat), in bo- dies interred alone ; but that the accumu- lated bodies of the common graves only were subject to this change. On a very attentive examination of a number of bo- dies passed to this state, M. Fourcroy re- marked, 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 gray 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, mus. cles, 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 compart- ments and vesicles of which they very well represented. By examining this substance in the dif- ferent 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 tendon* 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 degree by mere juxtaposition; the least effort being sufficient to separate them. The grave- diggers availed themselves of this circum- stance 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 these frocltes whitb wer$ changed intp the fatty ADI matter, the abdominal cavity had disap- peared. The teguments and muscles of this region being converted into the white matter, like the other soft parts, had sub- sided upon the vertebral column, and were so flattened as to leave no place for the viscera, and accordingly there was scarce- ly 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 intes- tines, the bladder, and even the liver, the spleen, the kidneys, and the matri^in fe- males. All these viscera were confound- ed together, and for the most part no tra- ces of them were left. Sometimes only certain irregular masses were found, of the same nature as the white matter, of differ- ent 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 assem- blage of facts no less singular and interest- ing. The external part of this cavity was flattened and compressed like the rest of the organs ; the ribs, spontaneously lux- ated in their articulations with the ver- tebrae, were settled upon the dorsal co- lumn ; their arched part left only a small space on each side between them and the vertebrae. The pleura, the mediastinum, the large vessels, the aspera arteria, and even the lungs and the heart, were no longer distinguishable ; but for the most part had entirely disappeared, and in their place nothing was seen but some parcels of the fatty substance. In this case, the matter which was the product of decom- position 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 pos- sessed by the former. Sometimes the ob- servers found in the thorax a mass irregu- larly 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 sub- jects, owed its existence to a superabun- dance of fat in this viscus, where it was found. For the general observation pre- sented itself, that in similar circumstances, the fat parts undergo this conversion more evidently than the others, and afford a larger quantity of the white matter. The external region in females exhibit- ed the glandular and adipose mass of the breasts converted into the fatty matter very white and v ery 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 disorganized exhibited neither tongue nor palate ; and the jaws, luxated and more or less displaced, were environ- ed with irregular layers of the white mat- ter. Some pieces of the same matter usu- ally occupied the place of the parts situ- ated in the mouth ; the cartilages of the nose participated in the general alteration of the skin ; the orbits instead of eyes con- tained white masses ; the ears were equal- ly disorganized; and the hairy scalp, hav- ing undergone 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 constantly contained the brain contracted in bulk ; blackish at the surface, and absolutely changed like the other organs. In a great number of sub- jects which were examined, this viscus was never found wanting, and it was al- ways 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 modifications were also various. Us con- sistence in bodies lately changed, that is to say, from three to five years, was soft and very ductile ; containing a great quan- tity 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 den- ser flakes. In several which were deposit- ed in dry earth, various portions of the fatty matter had become semi-transparent. Tfce aspect, the granulated texture, and brittleness of this dried matter, bore a considerable resemblance to wax. The period of the formation of this sub- stance had likewise an influence on its properties. In general, all that which had been formed for a long time was white, uniform, and contained no foreign sub- stance, or fibrous remains ; such, in par- ticular, was that afforded by the skin of the extremities. On the contrary, in bo- dies 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 al- ready altered and changed in its colour, was still distinguishable. Accordingly, as the conversion was more or less advan- ced, these fibrous remains were more or less penetrated with the fatty matter, in- terposed as it were between the intersti- ces 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 as. ADI AUI sertion. The skin, as has been remarked, becomes 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, neverthe- less, that the unctuous parts, and bodies charg-ed with fat, appear more easily and speedily to pass to the state under con- sideration. This was seen in the marrow, which occupied the cavities of the longer bones And again, it is not ro be supposed, but that the greater part of these bodies had been emaciated by the illness which terminated their lives ; notwithstanding which, they were all absolutely turned in- to 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 hu- man liver, to observe what would arise to it by the contact of the air. It partly pu- trefied, without, however, emitting any very noisome smell. Larvae of the dermes- tes and bruchus attacked and penetrated it in various directions ; at last it became dry, and after more than ten years' sus- pension, it was converted into a white fria- ble substance resembling dried agaric, which might have been taken for an earthy substance. In this state it had no percep- tible 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 iiad 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- verted it into soap, and in a word it ex- hibited all the properties of the fatty mat- ter 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 under- gone a change similar to that of the bodies in the burying-place ; and this fact suffi- ciently 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 be- fore mentioned, it was observed that the dry, friable, and brittle matter, was most commonly 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 Voi. i. [16] three years are required to convert a boety 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 ni- tric acid was very soft, and converted in- to the fatty matter ; that in the muriatic acid was not in that time so much altered; the sulphuric acid had turnQd the other black. M. Lavoisier thinks that this pro- cess may hereafter 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 re- mains, similar to that of the foregoing. The result of M. Fourcroy's inquiries into the ordinary changes of bodies recent- ly deposited in the earth, was not very ex- tensive. The grave-diggers informed him, that these bodies interred do not percep- tibly change colour for the first seven or eight days ; that the putrid process disea- gages elastic fluid, which inflates the ab- domen, and at length bursts it ; that this event instantly causes vertigo, faintness, and nausea in such persons as unfortu- nately are within a certain distance of the scene where it takes place ; but that when the object of its action is nearer, a sudden 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 busi- ness they are engaged in, excepting at this period, which they regard with the utmost terror. They resisted every in- ducement and persuasion which these philosophers made use of, to prevail on them to assist their researches into the na- ture of this active and pernicious vapour. M. Fourcroy takes occasion from these facts, as well as from the pallid and un- wholesome appearance of the grave-dig- gers, 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 1 through the successive degrees of the or- dinary putrefaction ; and this destruction is more speedy, the warmer the tempera- ture. But if these insulated bodies be dry and emaciated; if the place of deposition be likewise dry, and the locality and other circumstances such, that the earth, so far from receiving moisture from the atmos- phere, becomes still more effectually ADI ADI parched by the solar rays; the animal Cilices are ' volatilized and absorbed, the solids contract and harden, and a peculiar species of mummy is produced. But eve- ry circumstance is very different in the common burying-grounds. Heaped toge- ther almost in contact, the influence of ex- ternal bodies affects them scarcely at all, and they become abandoned to a peculiar disorganization, which destroys their tex- ture, and produces the new and most per- manent state of combination here describ- ed. From various observations which 1 do not here extract, it was found, that this fatty matter was capable of enduring in these burying-places for thirty of forty years, and is at length corroded and car- ried oft* by the aqueous putrid humidity which there abounds. Among other interesting facts afforded by the chemical examination of this sub- stance, are the following from experi- ments by M. Fourcroy. 1. This substance is fused at a less de- gree of heat than that of boiling water, and may be purified by pressure through a cloth, which disengages a portion of fi- brous and bony matter. 2. The process of destructive distillation by a very gradu- ated heat was begun, but not completed on account of its tediousness, and the lit- tle promise of advantage it afforded. The products which came over were water charged with volatile alkali, a fat oil, con- crete volatile alkali, and no elastic fluid during the time the operation was contin- ued. 3. Fragments of the fatty matter ex- posed to the air during the hot and dry summer of 1786 became dry, brittle, and almost pulverulent at the surface. On a careful examination, certain portions were observed to be semi-transparent, and more brittle than the rest These possessed 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 semi- transparent substance resembling wax. This was taken from the surface of the soapy liquor, which being then passed through the filter, left a white soft shining tnatter, which was fusible and combusti- ble. 5. Attempts were made to ascertain the quantity of volatile alkali in this sub- stance 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 like- wise to disengage the last portions. The Caustic volatile alkali, with the assistance of a gentle heat, dissolved the fatty mat- ter, and the solution became perfectly clear and transparent at the boiling tem- perature of the mixture, which was 185 F. 6. Sulphuric acid, of the specific gra- vity 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 se- veral 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, howev er, produce any indisposition either in him- self or his assistants. By dilution with wa- ter, and the ordinary processes of evapo- ration 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 phe- nomena 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, af- ter this process, affords by evaporation a portion of that waxy matter which is se- parable by acids, and is therefore the only portion soluble in cold alcohol. The quan- tity of fatty matter opera' ed on, was 4 ounces, or 2304 grains, of which the boil- ing spirit took up the whole except 26 grains, which proved to be a mixture of 20 grains of ammoniacal soap, and 6 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 af- ford 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 al- kali, by exposure to the air for three years, was almost totally dissolved by the cold al- cohol. The concrete oily or waxy substance obtained in these experiments constitutes the leading object 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 ADI the less disposed the acid may be to ope- rate in the way of combustion. It is requi- site, 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 co- lour of the tvaxy matter is grayish ; and tho-.igh exposure to the air, and also the action of the oxygenat. d muriatic acid did produce tn apparent whiteness, it never- theless disappeared by subsequent fusion. No metiod was discovered by which it ould b~ permanently bleached. The nature of this wax or fat is differ- ent from that of any other known substance of ths like kind. When slowly cooieil af- ter fusion, its texture appears crystalline or shivery, like spermaceti ; but a speedy cooling gives it a semi-transparency re- sembling wax. Upon the whole, never- theless, 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 i27F. ; Dr. Bostock says 92. Spermaceti requires 6 more of heat to fuse it, (according to Dr. Bostock 2j). The spermaceti did not so speedily be- come brittle by cooling as the adipocere. One ounce of alcohol of the strength be- tween 39 and 40 degrees of Baume's areo- meter, dissolved when boiling hot 12 gros of this substance, but the same quantity in like circumstances dissolved only 30 or 06 grains of spermaceti. The separation of these matters was also remarkably differ- ent, 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 ex- cess of ammonia can produce such an ef- fect with spermaceti M. Fourcroy concludes his memoir with some speculations on the change to which animal substances in peculiar circum- stances are subject. In the modern che- mistry, soft animal matters are considered as a compos.tionof the oxides of hydrogen and carbonated azote, more complicated than those of vegetable matters, and therefore more incessantly tending to al- teration. If then the carbon be conceived to unite with the oxygen, either of the xvater which is present, or of the other animal matters, 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 principle so abun- dant in animal matters, will form ammonia by combining with the hydrogen ; part of this will escape in the vaporous form, and ADI the rest will remain fixed in the fatty mat* ter. The residue of the animal mattera deprived of a great part of their carbon, of their oxygen, and the whole of their azote, will consist of a much greater pro- portion of hydrogen, together with car- bon and a minute quantity of oxygen. This, according to the theory of M. Four- croy, constitutes the waxy matter, or adi- pocere, which in combination with ammo- nia forms the animal soap, into which the dead bodies are thus converted. Muscular fibre, macera: ed in dilute nitric acid, and afterwards well washed in warm water, atiords 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 pro- cured for chemical experiment. Ambergris appears to contain adipocere in large quantity, rather more than half of it being of this substance. * This curious substance has been more recently examined by Chevreul. He found it composed of a small quantity of ammo- nia, potash, and lime, united to much mar- garine, and to a very little of another fatty matter different from that. Weak muri- atic acid seizes the three alkaline bases. On treating the residue with a solution of potash, the margarine is precipitated in the form of apearly subs 1 . ance, while the other fat remains dissolved. Fourcroy being- of opinion that the fatty matter of animai car- cases, 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. Che- vreul that these substances are very dif- ferent 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 incomplete putrefaction. Mary Howard, aged 44, died on the 1 2th 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 us.ial 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 181 ) the body >vas 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 cer- tain intestinal construction, Sir E. ob- ADI AER serves, that the current of water which passes through their colon, while the locu- lated lateral parts are full of solid matter, places the solid contents in somewhat sim- ilar circumstances to dead bodies in the banks of a common sewer. The circmstance of ambergris, which contains 60 per cent, of fat, being found in immense quantities in the lower intestines of the spermaceti whales, and never higher tip than seven feet from the anus, is an un- deniable 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 absor- bents, under the influence of disease, not acting so as to take it in. o the constitution. In the human colon, solid masses of fat are sometimes met with in a diseased state of that canal, and are called scybala, A description and analysis by Dr. Lire 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 com- municated by Dr. Babington, of fat form- ed in the intestines of a girl four and a half years old, and passing oil by stool. Mr. Brande found, on the suggestion of Sir E. Home, that muscle digested in bile, is con- vertible 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 gen- tleman after six days constipation, yielded, on infusion in water, a fatty film. This process of forming fat in the lower intes- tines by means of bile throws considera- ble light upon the nourishment derived from clysters, a fact well ascertained, but which could not be explained. It also ac- counts 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 dif- ferent animals. This property of the bile explains likewise the formation of fatty concretions in the gall bladder so common- ly met with, and which, from these experi- ments, appear to be produced by the ac- tion of the bile on the mucus secreted in the gall bladder ; and it enables us to un- derstand how want of the gall bladder in children, from mal-formation, 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 received into the circulation, and deposited in al- most 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 ex- ceeds the consumption, its accumulation Becomes a disease, and often a very dis- tressing one. See BILIARY concretions and MARGARINE.* * ADIT, in mining, is a subterraneous passage slightly inclined, about six feet high and two or three feet vide, 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 drain-* ing by a steam-engine from % greater depth, the water need be raised only to the level of the adit. There is a^ood ac- count of the Cornish adits by Mr. V/. Phil- lips, Trans. Geol. Soc. vol. ii.-, and cf adits in general, article Galerie, Brongiuart'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. * ADUI.AHIA. See FELDSPAR.* AERATED ALKALINE WATER. See Aw* (CARBONIC). AEIUAL Acin. See ACID (CARBONIC). * AKROLITE or METEORIC STONE. See MiTEOROLITB.* * 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 as- certain 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 capacity is one cubic inch. This tube is inserted into another tube of near- ly equal length, supported on a sole. The first tube is sustained at any height within the second by means of a spring. Five cubic inches of atmospheric air, at a me- dium 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 occupied 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, de- noting 5 cubic inches. The upper and lower halves of the tube are each divided into 5 parts, representing- tenths of a cubic inch. The external tube has a scale of in- ches attached. Journal of Science, vol. v. See GAS.* * AEROSTATION. A name commonly, but not very correctly, given to the art of rais- ing 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 possi- ble shapes, the globular admits the great, est 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 contain the least quantity A&A AGA of cloth, of the least surface. The sphe- roidal form is therefore best fitted for aerostation. Varnished lu: estring or mus- lin is employed for the envelopes. The following table shows the relation betwixt the diameters, surfaces, and capacities of spheres .- Diameters. Surfaces. Capacities. 1 3.141 0.523 2 12.567 4.188 3 28.274 14.137 4 50.265 33.51 5 78.54 65.45 10 314.159 523.6 15 706.9 1767.1 20 1256.6 4189. 25 1963.5 8181. 30 2827. 14137. 40 5026. 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 com- pute the total weight of the balloon. A cubic foot of atmospheric air weighs 527 gr. 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 consider every cubic foot of included gas, to have by itself a bouyancy of fully one ounce avoirdupois. Hence a balloon of 10 feet diameter will have an ascensional force of fully 524 oz. or 33 Ibs. minus the weight of the 314 su- perficial feet of cloth ; and one of 30 feet diameter, a buoyancy 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 VARXISH.* JETITES, or EAGLE STONE, is a name that has been given to a kind of hollow geodes of oxide of iron, often mixed with a larger or smaller quantity of silex and alumina, containing in their cavity some concre- tions, which rattle on shaking the stone. It is of a dull pale colour, composed of con- centric layers of various magnitudes, of an oval or polygonal form, and often polish- ed. Eagles were said to carry them to their nests, whence their name ; and su- perstition formerly ascribed wonderful vir- tues to them. AFFINITY (CHEMICAL). See ATTRAC- TION (CHEMICAL). AGALMATOLITE. See BILDSTEIX. 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 con- siderable portion of nitrogen, and yield ammonia by distillation. Pix)f. Proust has likewise discovered xin them the benzoic acid, and phosphate of lime. A few of the species are eaten in this country, but many -are recorded to have produced poisonous effects ; though hi some foreign countries, particularly in Russia, very few are rejected. Perhaps it is of importance, that they should be fresh, thoroughly dressed, and not of a coriaceous texture. The Russians, how- ever, are very fond of the A. pipcrattis, which we deem poisonous, preserved with salt throughout the winter : and our ketchup is made by sprinkling mushrooms with salt, and letting them stand till great part is resolved into a brown liquor, which is then boiled up with spices. The A. piperatus has been recommended in France to consumptive people. The Jl. muscarius has been prescribed in doses of a few grains in cases of epilepsy and palsy, subsequent to the drying up of eruptions. In pharmacy two species of boletus have formerly been used under the name of agaric. The B. pini 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 r and the B. igniarius, spunk, or touchwood, called female agaric, was applied exter- nally 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 quickness of their growth, and decay, as well as for the foetor attending their spon- taneous decomposition, v/ere unaccount- ably neglected by analytical chemists, though capable of rewarding their trouble, as is evinced by the recent investigations and discoveries of MM. Vauquelin and Braconnot. The insoluble fungous portion of the mushroom, though it resembles woody fibre in some respects, yet being less soluble than it in alkalis, and yielding a nutritive food, is evindently 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. Jlgancus campestris, an ordinary ar- ticle of food, analyzed by Vauquelin, gave the following constituents : 1. Adipocere. On expressing the juice of the agaric, and subjecting the remainder to the action of of boiling alcohol, a fatty matter is extrac- ted, 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 AGA AGA heated it evolves the odour of roasting 1 'meat, like osmazome; 6. An animal matter not soluble in alcohol ; 7. Fungin ; 8. Acetate of potas'h- 2. Jlgaricus volvacew afforded Bracon- not fungin, gelatin, vegetable albumen much phosphate of potasi\ some acetate of potash, sugar of mushrooms, a brown oil, adipocere, wax, a very fugaceous deleterious matter, uncombineci acid, sup- posed to be the acetic, benzoxc acid, muriate of potash, and a deal of water ; in all 14 ingredients. 3. Jlgaricus acris or piper atus, 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. Jlgaricus stypticus. From twenty parts of this, Braconnot obtained of resin and adipocere 1.8, fungin 16.7, of an un- known gelatinous substance, a potash salt, and a fugaceous acrid principle 1.5. 5. Jlgaricus bnlbosus, was examined by Vauquelin, who found the following con- stituents; an animal matter insoluble in alcohol, osmazome, a soft fatty matter of a yellow colour and acrid taste, an acid salt, (not a phosphate). The insoluble substances of the agaric yielded an acid by distillation. In Orfila's Toxicology several instances are detailed of the fatal effects of this species of mushroom on the human body. Dogs were killed with- in 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 incon- venience after swallowing it, during the first ten hours ; stupor, cholera, convul- sions, and painful cramps are the usual symptoms of the poison in men. The best remedy is an emetic. 6. Jlgaricus theogolus. In this Vauque- lin found sugar of mushrooms, osmazome, a bitter acrid fatty matter, an animal matter not soluble in alcohol, a salt containing a vegetable acid. 7. Jlgaricus muscarius, Vauquelin's analysis 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 soldiers ate, at two leagues from Polosck in Russia, mushrooms of the above kind. Four of them, of a robust constitution, who conceived themselves proof against the consequences, under which their feebler companions were beginning to suffer, refused obstinately to take an emetic. In the evening the fol- lowing symptoms appeared: Anxiety, sense of suffocation, ardent thirst, intense griping pains, a small and irregular pulse, universal cold sweats, changed expression pi countenance, violet tint of the nose and lips, general trembling, fetid stools. These symptoms becoming worse, they were carried to the hospital. Coldness and livid colour of the limbs, a difcadful 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 putre- faction seemed advancing very rapidly,* AGAIUCUS MIM: KALIS, the mountain milky 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 internally in haemorrhages, strangury, gravel, and dysenteries; and externally as an application to old ulcers, and weak and watery eves. M. Fabroni calls by the name of mineral agaric, or fossil meal, a stone of a loose consistence found in Tuscany in consider- able abundance, of which bricks may be made, either with or without the addition of a twentieth part of argil, so light as to float in water; and which he supposes the ancients used for making 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, mag- nesia 15, water 14, argil 12, lime 3, iron 1. Kirwan calls it argillo-murite. * AGATE A mineral, whose basis is cat cedony, blended with variable proportions of jasper, amethyst, quartz, opal, helio- trope, and carnelian. Ribbon agate con- sists of alternate and parallel layers of cal- cedony with jasper, or quartz, or amethyst. The most beautiful comes from Siberia and Saxony. It occurs in porphyry and gneiss. Brecciated agate ; a base of ame- thyst, containing fragments of ribbon agate, constitute this beautiful variety. It is of Saxon origin. Fortification agate, is found in nodules of various imitative shapes, im- bedded in amygdaloid. This happens at Oberstein on the Rhine, and in Scotland. On cutting it across and polishing it, the interior zig-zag parallel lines bear a consi- derable resemblance to the plan of a mo- dern fortification. In the very centre, quartz and amethyst are seen in a splinte- ry mass, surrounded by the jasper and cal- cedony. Mocha stone. Translucent cal- cedony, containing dark outlines of arbor- ization, like vegetable filaments, is called Mocha stone, from the place in Arabia AGA AGR where it is chiefly found. These curious appearances were ascribed to depositesof iron or manganese, but more lately they have been thought to arise from mineral- ized plants of the cryptogamous class. Jlfoss agate, is a calcedonv with variously coloured ramifications of a vegetable form, occasionally traversed with irregular veins of red jasper. Dr. M'Culloch has recent- ly detected, what Datibenton merely con- jectured, in mocha and moss agates, aqua- tic confervae, unaltered both in colour and form, and also coated with iron oxide. Mosses and lichens have also been observ- ed, 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. Hol- low nodules of agate called geodes, present interiorly crystals of quartz, colourless or amethystine, having occasionally scattered crystals of stilbite, chabasie, and capillary mesotype. These geodes are very com- mon. Bitumen has been found by M. Pa- trin 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 occasionally in their cavities. These are chiefly found in insu- lated blocks of a lava having an earthy fracture. When they are cracked, the li- quid escapes by evaporation ; it is easily restored by plunging them for a little in hot water. Agates are artificially colour- ed by immersion 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 sur- face to be polished is first coarsely ground by large millstones of a hard reddish sand- stone, moved by water. The polish is af- terwards given on a wheel of soft wood, moistened and imbued with a fine powder of a hard red tripoli found in the neigh- bourhood. M. Faujas thinks that this tri- poli is produced by the decomposition of the porphyrated rock that serves as a gangue to the agates. The ancients em- ployed agates for making cameos. (See CALCEDONT.) Agate mortars are valued 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 occi- dental is of various colours, and often vein- ed 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 petrosilex, 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 aggre- gate, 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 ag- gregate 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 compo- nent parts, namely, the alkali and the acid ; which are still further resolvable in- to their constituent principles. * AGRICULTURE, considered as a depart- ment of chemistry, is a subject of vast im- portance, but hitherto much neglected. When we consider that every change in the arrangements of matter is connected with the growth and nourishment of plants; the comparative values of their produce as food ; the composition and constitution of soils ; and the manner in which lands are enriched by manure, or rendered fer- tile by the different processes of cultiva- tion, we shall not hesitate to assign to che- mical agriculture, a high place among the studies of man. If land be unproductive, and a system of ameliorating it is to be at- tempted, the sure method of attaining 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 easily be discovered by chemical analysis. Some lands of good apparent texture are yet eminently bar- ren; and common observation and com- mon practice afford no means of ascertain- ing the cause, or of removing the effect. The application of chemical tests in such cases is obvious; for the soil must contain some noxious principle which may be easi- ly discovered, and probably easily destroy- ed. 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 mat- ter. Is there a defect of calcareous mat- ter? The remedy is obvious. Is an excess of vegetable matter indicated ? It may be removed by liming, paring, and burning, Is there a deficiency of vegetable matter? It is to be supplied 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 absolute!)! poisonous to plants. There has been n question on which more difference of op nion has existed, than that of the state i AIR AIR which tnanure ought to be ploughed into land ; whether recent, or when it has gone through the process of fermentation. But whoever will refer to the simplest princi- ples of chemistry, cannot entertain a doubt on the subject. As soon as dung.begins to decompose, it throws off' its volatile parts, which are the most valuable and most efficient. Dung which has ferment- ed so as to become a mere soft cohesive mass, has generally lost from one-third to one-half of its most useful constituent ele- ments. See the articles, ANALYSIS, MA- NURE, SOILS, VEGETATION, and Sir H. Da- vy'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 elasticity, and are not condensable into the liquid state by any degree of cold hi- therto produced ; but as this term is com- monly 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. Am (ATMOSPHERICAL or COXMOX). The immense mass of permanently elastic fluid which surrounds the globe we inhabit, must consist of a general assemblage of every kind of air which can be formed by the various bodies that compose its sur- face. Most of these, however, are absorb- ed by water ; a number of them are decom- posed by combination with each other; and some of them are seldom disengaged in considerable quantities by the proces- ses of nature. Hence it is that the lower atmosphere consists chiefly of oxygen and nitrogen, together with moisture and the occasional vapours or exhalations of bo- dies. The upper atmosphere seems to be composed of a large proportion of hydro- gen, a fluid of so much less specific gravi- ty 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 bo- realis and fire-balls. It may easily be un- derstood, 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 extend progressively, though rapidly, in flashings from the place where it commen- ces ; and thai when by any means a stream of inflammable air, in its progress toward 1he upper atmosphere, is set on fire atone end, its ignition may be much more rapid lhan what happens higher up, where oxy- en 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 pro bably be objected, that the air on the sum- mit of Mont Blanc, and that brought down from still greater heights by M. Gay-Lus- sac, in an aerostatic machine, gave, on analysis, no product of hydrogen. But the lowest estimate of the height of luminous meteors, is prodigiously greater lhan the highest elevaxions to which man has reach- ed.* See COMBUSTION. That the air of the atmosphere is so transparent as to be invisible, except by the blue colour it reflects when in very large masses, as is seen in the sky or re- gion above us, or in viewing- extensive landscapes; that it is without smell, ex- cept that of electricity, which it sometimes very manifestly exhibits; altogether with- out taste, and impalpable : not condensa- ble by any degree of cold into the dense fluid state, though easily changing its di- mensions with its temperature ; that it gravitates and is highly elastic, are among the numerous observations and discove- ries, which do honour to the sagacity of the philosophers of the seventeenth cen- tury. They likewise knew that this fluid is indispensably necessary to combustion ; but no one, except the great, though ne- glected, 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 1 bodies in solution. It takes up water in considerable quantities, with a diminution of its own specific gravity ; from which circumstance, as well as from the conside- ration that water rises very plentifully in the vaporous state in vacua, it seems pro- bable, that the air suspends vapour, not so much by a real solution, as by keeping its particles asunder, and preventing their condensation. Water likewise dissolves or absorbs air. Mere heating or cooling' does not affect the chemical properties of atmospherical air; but actual combustion, or any process of the same nature, combines its oxygen, and leaves its nitrogen separate. When- ever a process of this kind is carried on in a vessel containing atmospherical air, which is enclosed either by inverting the vessel over mercury, or by stopping its aperture in a proper manner, it is found that the process ceases after a certain time; and that the remaining air, *(if a combus- tible body capable of solidifying the oxy- gen, such as phosphorus, have been em- ployed,)* has lost about a fifth part of its volume, and is of such a nature as to be incapable of maintaining any combustion for a second time, or of supporting the life of animals. From these experiments it is clear, that one of the following deduc- tions must be true:- 1. The combustible body has emil AIR )ody lias emitted some principle, which, by combining" with the air, has rendered it unfit for the purpose of further combus- tion ; 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 principle has been emitted, which has changed the original properties of the re- mainder. The facts must clear up these theories. The first induction cannot be true, because the residual air 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 exist- ence of phlogiston, or a principle of in- flammability ; and the third must be adopt- ed by those who maintain that such a prin- ciple escapes from bodies during- combus- tion. This residue was called phlogisti- cated air, in consequence of such an opi- nion. 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 subtraction of one of its principles : for the pure or vital part of the air may unite with inflammable air supposed to exist in a fix- ed 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 inflamma- ble air or phlogiston is disengaged, and unites with the aeriform residue, this re- sidue will not be heavier than before, un- less 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 men- tion; but it has been sufficiently proved by various experiments, that combustible bodies take oxygen from the atmosphere, and leave nitrogen ; and that when these two fluids are again mixed, in due propor- tions, they compose a mixture not differ- ing from atmospherical air. The respiration of animals produces the same effect on atmospherical air as com- bustion does, and their constant heat ap- pears 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 oxy- gen, or a mixture which contains it. Pure oxygen maintains the life of animals much longer than atmospherical air, bulk for bulk. Vofc. f. { 17 ] AIR * It is to be particularly observed, how* ever, that, in many cases of combustion, the oxygen of the air, in combining with the combustible body, produces a com- pound, not solid or liquid, but aeriform. The residual air will therefore be a mix- ture of the nitrogen of the atmosphere with the consumed oxygen, converted in- to another gas. Thus, in burning char- coal, 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 at- mosphere, which is continually consumed in respiration and combustion, is again restored to that fluid. In fact there ap- pears, as far as an estimate can be formed of the great and general operations of na- ture, to be at least as great an emission of oxygen, as is sufficient to keep the gene- ral mass of the atmosphere at the same degree of purity. Thus, in volcanic erup- tions there seems to be at least as much oxygen emitted or extricated by fire from various minerals, as is sufficient to main- tain the combustion, and perhaps even to meliorate the atmosphere. And in the bodies of plants and animals, which ap- pear in a great measure to derive their sus- tenance and augmentation from the atmos- phere 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 im- bibe and decompose the air of the atmos- phere, retaining carbon, and emitting the vital part. Lastly, if to this we add the decomposition of water, there will be nu- merous occasions in which this fluid will supply us with disengaged oxygen ; while, by a very rational supposition, its hydro- gen may be considered as having entered into the bodies of plants for the formation of oils, sugars, mucilages, &c. from which it may be again extricated. To determine the respirability or purity of air, it is evident that recourse must be had to its comparative efficacy in maintain- ing- combustion, or some other equivalent process. This subject will be considered under the article EUDTOMETKH. From the latest and most accurate expe- riments, the proportion of oxygen in at- mospheric air is by measure about 21 per cent ; and it appears to be very nearly the same, whether it be hi 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 ascer* turned by Gay-Lussar in his aerial voyage AIR AIR- in September 1805. 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 i21, ac- cording to Kirwan, and of 139 to l2u ac- cording 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 con- trary to the fact. On the other hand it has been urged, that they cannot be in the state of chemical combination, be- cause they both retain their distinct pro- perties unaltered, and no change of tem- perature or density takes place on their union. But perhaps 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 atmos- phere is exposed, may be sufficient to prevent two fluids, differing not more than oxygen and nitrogen in gravity, from separating by subsidence, though simply mixed. On the contrary, it may be ar- gued, that to say chemical combination cannot take place without producing new properties, which did not exist before in the component parts, is merely begging the question; for though this generally appears to be the case, and ofteu in a very striking manner, yet combination does not always produce a change of properties, as appears in M. Biot ; s experiments with va- rious substances, of which we may instance water, the refraction of which is precisely the mean of that of the oxygen and hy- drogen, which are indisputably combined in it. To get rid of the difficulty, Mr. Dalton of Manchester framed an ingenious hypo- thesis, 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 inter ruption from the presence 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 cer- tain facts. In the case of the carbonic acid g-as 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 argument for his hypothesis, that oxygen and hydrogen gases, when mixed by agitation, do not separate on standing. But why should either oxygen or hydro- gen require agitation, to diffuse it through a vacuum, in which, according to Mr. Dalton, it is placed? C. The theory of Berthollet appears con- sistent with all the facts, and sufficient to account for the phenomenon. If two bo- dies be capable of chemical combination, their particles must have a mutual attrac- tion for each other. This attraction, how- ever, 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 bo- dy 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 counteracted by opposing circum- stances. 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; itself to such a degree as to form them in- to a chemical compound, though it ope- rates with sufficient force to prevent their separating by their difference of specific gravity. Thus the state of the a'mosphere is accounted for, and every difficulty ob- viated, without any new hypothesis. * The exact specific gravity of atmos- pherical 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 atmospherical air ap- pears to be 0.001220, water being repre- sented by 1.000000. This relation ex- pressed fractionally is y^ or water is 820 times denses 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 cu- bic inches of air by Biot's experiments will weigh 30. 808 gr. and by Mr. Rice s esti- mate 30.519. He considers with Dr. ProuJ: the atmosphere 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= 0.000940 0.2 oxy. 0.001340 0.000268 0.001208 The numbers are transposed in the An- nals of Philosophy by some mistake.. ALA ALB M M. Biot and Arago found the speci- fic gravity of oxygen to be - - l.la;59 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 ana- logies, it must be confessed, favour Dr. Prout's proportions; but the greater num- ber of experiments on the composition and density of the atmosphere agree with Biot's results. Nothing can decide these fundamental chemical proportions except a new, elaborate, and most minutely accu- rate series of experiments. We shall then know whether the atmosphere contains in volume 20 or 21 per cent of oxygen. See METEOUOLOGY.* ALABASTEU. 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 external character and appear- ance than their component parts, alabas- ters are those which have a greater or less degree of imperfect transparency, a gran- ular texture, are softer, take a duller po- lish than marble, an^[ are usually of a whiter colour. Some stones, however, 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 ap- plying this name only to such opaque, consistent, and semi-transparent stones, as are composed of lime united with the sul- phuric acid. But the term is much more frequent among masons and statuaries than chemists. Chemists in general con- found the alabasters among the selenites, gypsums, or plaster of Paris, more espe- cially when they allude only to the com- ponent parts, without having occasion to consider the external appearance, in which only these several compounds dif- fer from each other. As the semi-opaque appearance and granular texture arise merely from a dis- turbed or successive crystallization, which would else have formed transparent spars, it is accordingly found, that the calcareous stalactites, or drop-stones, formed by the- transitioa of water through the roofs d 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 carbonic acid; while the alabaster of the chemists is formed of the same earth and sulphuric acid, as has already been remarked. * ALBKV A mineral discovered at Mo- naberg, near Aussig, in Bohemia ; and be- ing of an opaque white colour, has been called, by Werner, albin. Aggregated crystalline laminae constitute massive albin. Small crystals of it in right prisms, whose summits consist of four quadrangular planes, are found sprinkled over mamme- lated masses in cavities.* See ZEOLITE. ALBUM GRJECTJM. Innumerable are the in- stances of fanciful speculation and absurd credulity in the invention and application of subjects in the more ancient ma-terra medica. The white and solid excrement of dogs, which subsist chiefly on bones, has been received as a remedy in the medical art, under the name of Album Grxcum. It consists, for the most part, of the earth of bones, or lime in combin- ation with phosphoric acid. ALBUMEN. This substance, which derives 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 having 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 i' there long before. Vauquelin says it exists also in the mineral wa er of Plombieres. Mr. Seguin has found it in remarkable quantity 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 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. ALB ALB Pure alkalis dissolve it, even after coagu- lation. It is precipitated by muriate of mercury, nitro-muriate of tin, acetate of lead, nitrate of silver, muriate of gold, infusion of galls, and tannin. The acids and metallic oxides coagulate albumen, On the addition of concentrated sulphuric 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 R disengages from it abundance of azotic gas ; and if the heat be increased prussic acid is formed, after which carbonic acid and carburette^d hy- drogen 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, ammpniacal gas is evolved, and the cal- cination 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 agitating white of egg with ten or twelve times its weight of alcohol. This seizes the water which held the albumen in solu- tion; and this substance is precipitated under the form of white flocks or filaments, which cohesive attraction renders insolu- ble, and which consequently may be freely washed with water. Albumen thus ob- tained is like fibrin, solid, white, insipid, inodorous, denser than water, and without action on vegetable colours. It dissolves in potash and soda more easily than fibrin; but in acetic acid and ammonia with more difficulty. 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 ihe characteristic coagula- tion of albumen by heat to its oxygenation. But cohesive attraction is the real cause of the phenomenon. In proportion as the temperature rises, the particles of water and albumen recede from each other, their affinity diminishes, and then the albu- men precipitates. However, by uniting albumen with a large quantity of water, we diminish its coagulating property to such a degree, that heat renders the solu- tion merely opalescent. A new-laid egg yields a soft coagulum by boiling ; but when, by keeping, a portion of the water has transuded so as to leave a void space within the shell, the concentrated albu- men affords a firm coagulum. An analo- gous phenomenon is exhibited by acetate of alumina, a solution of which, being heat- ed, 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 T ^ of dry albumen forms by heat a solid coagulum ; but when it contains only T l ^ f it gives a glairy liquid. One thousandth part, however, on applying heat, occa- sions opalescence. Putrid white of egg, and the pus of ulcers, have a similar smell. According to Dr. Bostock, a drop of a saturated solution of corrosive sublimate letfall into water containing -%-QQ-Q of albu- men, occasions a milkuiess and curdy pre- cipitate. On adding a slight excess of the mercurial solution to the albuminous li- quid, and applying heat, the precipitate which falls, being dried, contains in every 7 parts, 5 of albumen. Hence that salt is the most delicate test of this animal pro- duct. The yellow pitchy precipitate oc- casioned by tannin, is brittle 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 albumen 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. Bv the analysis of Gay-Lussac and Thenaru, lOO parts of albumen are foruied of 52 titte car- bon, 23.872 oxygen, 7.540 hydrogen, 15.70.5 ni;:rogen;or, in other terms,of 52.683 carbon, 27. 12'/ oxygen and hydrogen, in the proportions for constituting water, 15.705 nitrogen, arid 4.285 hydrogen in excess. The negative pole of a voltaic pile in high activity coagulates albumen; bui 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 me- tallic oxides, particularly the protoxide of iron. Orfila has found white of egg to be the best antidote to the poisoning effects of corrosive sublimate on the human sto- mach. As albumen occasions precipitates with the solutions of almost every metal- lic salt, probably it may act beneficially against other species of mineral poison.* From its coagulability albumen is of great use in clarifying liquids. See CLA- 1UFICATIO1V. It is likewise remarkable for the pro- perty 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 Somerset- shire was induced to employ 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 Jump of alum, till they coagulate, form the ALC ALC vlnmcurdof Riverius, or alum cataplasm of the London Pharmacopoeia, used to re- move inflammations of the eyes. * ALBURNUM. The interior white bark of trees.* * AicARRAZAi. A species of porous pottery made in Spain, for the purpose of cooling water by its transudation and co- pious evaporation from the sides of the vessel. M. Darcet gives the following as the analysis of the clay which is employed for the purpose : 60 calcareous earth, mixed with alumina and a little peroxide of iron, and 36 of siliceous earth, mixed with a little alumina. In working up the earths with water, a quantity of salt is ad- ded, and dried in it. The pieces are only half baked.* * ALOUEMT. A title of dignity, given in the dark ages, by the adepts, to the mystical art by which they professed to find the philosopher's stone, that was to transmute base metals into gold, and pre- pare the elixir ot life. Though avarice, fraud, and folly were their motives, yet their experimental researches were instru- mental in promoting the progress of che- mical discovery. Hence, in particular, metallic pharmacy derived its origin.* ALCOHOL. This term is applied in strict- ness only to the pure spirit obtainable by distillation and subsequent rectification from all liquids that have undergone vi- nous fermentation, and from none but such as are susceptible of it. But it is common- ly used to signify this spirit more or less imperfectly 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 distin- g s ished by the name of spirit of wine. At .present it is extracted chiefly from grain or molasses in Europe, and from the juice of the sugar-cane in the West Indies ; and in the diluted state in which it commonly ficcurs in trade, constitutes the basis of the several spirituous liquors called bran- dy, rum, gin, whiskev , and cordials, how- ever variously denominated or disguised. As we are not able to compound alco- hol immediately from its ultimate consti- tuents, 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 uni- ted into a new compound ; to distillation, by which this new compound, the alcohol is separated in a state of dilution with wa- ter, and contaminated with essential oil ; and to rectification, by which it is ultimate- ly freed from these. It appears to be essential to the fermen- tation of alcohol, that the fermenting fluid should contain saccharine matter, which is indispensable to that species of fermen- tation called vinous. 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 oft' the spirit ; and as the essential oil that rises in this process is of a more pleasant flavour than that of malt or molasses, the French brandies are preferred to any other; though even in the flavour of these 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 impreg- nated with its essential oil, and well known by the name of rum. The distillers in this country use grain, or molasses, whence they distinguish the products by the name of malt spirits, and molasses spirits. It is said that a very good spirit may be ex- tracted from the husks of gooseberries or currants, after wine has been made from them. As the process of malting developes the saccharine principle of grain, it would ap. pear to render it fitter for the purpose ; though it is the common practice to use about three parts of raw grain with one of malt. For this, two reasons may be assign- ed : by using raw grain the expense of malting is saved, as well as the duty on malt ; and the process of malting requires some nicety of attention, > 1-1 45th of its bulk. The laws of their expansion are still more different than the quantities. If the expansion of quicksilver be, as usual, taken for the standard, (our thermome- ters being constructed with that fluid,) the expansion of spirit is, indeed, progres- sively increasing with respect to that stan- dard, but not much so within the above- mentioned interval ; while water kept from freezing to 30, which may easily be done, will absolutely contract as it is heat- ed 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 increasing progression. Now, mixtures of these two substances will, as inay be supposed, approach to the less or the greater of these progressions, accord- ing as they are compounded of more spi- rit or more water, while their total expan- sion 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 determined only by trials. These were, therefore, the two other prin- cipal objects to be ascertained by experi- ment. The person engaged to make these ex- periments was Dr. Dollfuss, an ingenious Swiss gentleman then in London, who had distinguished himself by several publica- tions on chemical subjects. As he could not conveniently 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 repeated by Mr. Gilpin, clerk of the Roy- al Society; and as the deductions in this account will be taken chiefly from that ]ast set of experiments, it is proper here to describe minutely the method observed by Mr. Gilpin in his operation. This natu- rally resolves itself into two parts : the way ef making the mixtures, and the way of ascertaining their specific gravity. 1. The mixtures were ma'de by weight, as the only accurate method of fixing the proportions. In fluids of such very une- qual expansions by heat as water and alco- hol, if measures had been employed, in- creasing or decreasing in regular propor- tions to each other, the proportions of the masses would have been sensibly irregu- lar : now the latter was the object in view, namely, to determine the real quantity of spirit in any given mixture, abstracting the consideration of its temperature. Be- sides, if the proportions had been taken by measure, a different mixture should have been made at every different degree of heat. But the principal consideration was, that with a very nice balance, such as was employed on this occasion, quantities can be determined to much greater exact- ness by weight than by any practicable way of measurement. The proportions were therefore always taken by weight. A phial being provided of such a size as that it should be nearly full with the mix- ture, was made perfectly clean and dry, and being counterpoised, as much of the pure spirit as appeared necessary 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 calcula- ted. This quantity of water was then add- ed, with all the necessary care, the last portions being put in b^ 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 instantly begins to issue by drops, or a very small stream, upon raising the thumb. Water being thus introduced in- to the phial, till it exactly counterpoised the weight, which having been previously computed, was put into the opposite scale, the phial was shaken, and then well stop- Eed with its glass stopple, over which :ather was tied very tight, to prevent evaporation. No mixture was used till it had remained in the phial at least a month, for the full penetration to have taken place ; and it was always well shaken be- fore 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 convenient vessel with them, and ascertaining the increase of weight it acquires. In both cases a stan- dard 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 ALC ALC vessel filled with water. The latter was preferred, for the following- reasons : When a ball of glass, which is the pro- perest kind of solid body, is weighed in any spirituous or watery fluid, the adhe- sion of the fluid occasions some inaccura- cy, and renders the balance comparatively sluggish. To what degree this effect pro- ceed is uncertain ; but from some expe- riments 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 temperatures, would give oc- casion to such an evaporation as to alter essentially the strength of the mixture. It eeemed also as if the temperature of the fluid under trial could be determined 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 weigh- ed remains immersed in it; and as some time must necessarily be spent in the weighing, the change of heat which takes place during that period will be unequal through the mass, and may occasion a sen- sible 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 precision, because the neck of the vessel employed, containing about ten grains, was filled up to the mark with spi- rit 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 quantity of it may be estimated very nearly. Fi- nally, 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 ; be- cause 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, prov- ed a material convenience. The particu- lar disadvantage in the method of weigh- ing in a vessel, is the difficulty of filling it with extreme accuracy ; but when the ves- sel is judiciously and neatly marked, the error of filling will, with due care, be ex- ceedingly minute. By several repetitions of the same experiments, Mr. Gilpin seem- ed to bring it within the l-15000th part of the whole weight. The above-mentioned considerations in- duced T)r. Blagden, as well as the gentle- men employed in the experiments, to give the preference to weighing the fluid it- self; and that was accordingly the method practised both by Dr. Dollfuss and Mr. Gilpin in their operations. The vessel chosen as most convenient Yoi. i. [18] for the purpose was a hollow glass ball, terminating in a neck of small bore. That which Dr. Dollfuss used held 5800 grains of distilled water ; but as the balance was so extremely accurate, it was thought ex- pedient, upon Mr. Gilpin's repetition of the experiments, to use one of only 2965 grains capacity, as admitting the heat of any fluid contained in it to bf: more nicely determined. The ball of this vessel, which may be called the weighing- bottle, mea- sured 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 ba- rometer tube, .25 of an inch in bore, and about 1 inch long; it was perfectly cy- lindrical, and, on its outside, 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 dia- mond. The glass of this bottle was not very thick; it weighed 916 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 temperature, 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 ther- mometer was then passed through the neck of the bottle into the contained li- quor, which showed whether it was above or below the intended temperature. In the former case the bottle was brought in- to colder air, or even plunged for a mo- ment into cold water; the thermometer in the mean time being frequently put in- to the contained liquor, till it was found to sink to the right point. In like man- ner, when the liquor was too cold, the bottle was brought into warmer air, im- mersed in warm water, or more common- ly held between the hands, till upon re- peated trials with the thermometer the just temperature was found. It will be understood, that during the course ot this heating or cooling, the bottle was very frequently shaken between each immer- tion of the thermometer ; and the top of the neck was kept covered, either with the finger, or a silver cap made on pur- pose, as constantly as possible. Hot wa- ter 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 em- ployed, the ball of the bottle was plunged into it, and again quickly lifted out, with the necessary shaking- interposed, as often as was necessary for communicating tbe ALC ALC 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 bot- tle exactly to the mark upon the neck, which was done with some of the same li- quor, 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 contained in the bottle ; but as the^whole quantity 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 oc- casioned an error of only l-30th of a de- gree in the temperature of the mass. Enough of the liquor was put in to fill the neck rather above the mark, and the su- perfluous 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 bot- tom or centre of this concavity was the part made to coincide with the mark round the glass ; and in viewing it care was ta- ken, 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 exact- ness possible. The spirit employed by Mr. Gilpin was furnished to him by Dr. Dollfuss, under whose inspection it had been rectified from mm supplied by government. Its speci- fic gravity, at 60 degrees of heat, was .82514. It was first weighed pure, in the above-mentioned bottle, at every five de- grees of heat, from SO to 100 inclusively. Then mixtures were formed of it, and dis- tilled 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 pro- portion 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 num- bers hence resulting are delivered in the following table; where the first column shows the degrees of heat; the second gives the weight of the pure spirit con- tained in the bottle at those different de- grees ; the third gives the weight of a mixture in the proportions 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; ?ndthe er- rors of the thermometers, 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 dif- ferent temperatures, heating it up from 30 to 100 ; hence some small error in its strength may have been occssioned in the higher degrees, by more spirit evaporat- ing than water: but this, it is believed, must have been trifling, and greater in- convenience would probably have result- ed 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 constructing the table of specific gravi- ties, as .825 only, a proportional deduc- tion being made from all the other num- bers. Thus the following table gives the true specific gravity, at the different de- grees of heat, of a pure rectified spirit, the specific gravity of which at 60 is .825, together with the specific gravities of different mixtures of it with water, at those different temperatures. ALC ALC Real Specific Gravities at the different Temperatures. Heat. The pure spirit 100 grains 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 grairs of spirit to 30 gr. ot water 100 grains of spirit to 35 gr. of water 100 graius of spirit to 40 gr. of water 100 grains of spirit to 45 gr. of water 100 grains of spirit to 50 gr. of water 30 C 83396 84995 8o95/ o6825 87585 88282 88921 89511 90054 .90558 91023 35 83672 84769 85^29 86587 87357 88059 88701 89294 89839 90345 90811 40 83445 84539) 85507 86351 87134 87338 83481 89073 89617 90127 90596 45 83214 843101 85277 86131 86905 87613 88255 88849 89396 89909 90380 50 82977 84076 85042 85902 86676 87384 88030 88626 89174 89684 90160 55 82736 83834 84802 85664 86441 87150 87796 88393 88945 89458 89933 60 82500 83599 84568 85430 86208 86918 87569 88169 88720 89232 89707 65 82262 83J6J! 84334 85193 85976 86686 87337 87938 88490 89006 89479 70 82023 83124 84092 84951 35736 86451 87105 87705 88254 88773 89252 75 8178'J 32d78 838ol 84710 85496 86212 86864 87466 88018 88538 89018 80 81530 32631 83603 84467 85248 85966 86622 87228 87776 88301 88781 85 81291 82396 83371 84243 85C36 85757 86411 87021 87590 88120 88609 90 81044 82150 83126 84001 84797 85518 86172 86787 87360 87889 88376 95 80794 81900 82877 83753 845JO 85272 85928 8C542 87114 87654 88146 too 805*8 81657 82639 83513 84038 85031 85688 86302 86879 87421 87915 100 100 1 100 100 160 TOO 100 100 100 100 Heat. grains of spirit to 56 gr. of water grains Of spirit to 60 gr. of svater grains of spirit 10 03 gr. of water grains of spirit to 70 gr. Of wa ?er grains OT spirit to 75 gr. of water grains of spirit to 80 gr. of water grains of spirit to 85 gr. of water grains of spirit to 90 gr. of water grains of spirit to 95 gr. of water gr. of spirit to 100 gr. of water 30 91449 91847 92217 92563 .92889 93151 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 95 90 85 80 | 75 70 65 60 55 50 Heat. grains of spirit to grains of spirit to grains of spirit to grains of grains o1 spirit to spirit to grains of spirit to grains of spirit to grains ol spirit te grains of spirit to grains of spirit to 100 gr.of 100 gr. of 100 gr. of 100 gr.of 100 gr. of 100 gr. ol 100 gr. of 100 gr.of 100 gr.of 100 gr o water. water. water. water. water. water. water. water. water. water. 30 .94447 .94675 .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 9596o 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 95392 80 92393 92646 92917 93201 93488 93785 94102 94431 94768 95111 ALC ALC Heat. 45 . 40 grains ofgr.iins of sv'irit to'spirit t lOOgr. of 100 gr. of grains of spirit to lor gr. of 30 grains of spirit to lOOgr.of 25 20 15 grains of] grains oflgrains of spirit to'spirit to spirit to l"0gr.of 100 gr of|100gr. of 10 grains of spirit to 100 gr. of s grains of spirit to 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 98U76 98397 98804 99344 40 96706 96967 97220 97472 97737 98033 98373 98795 99345 45 9 .563 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 982.-9 987u2 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 96708 97086 97495 97943 98454 99066 80 95467 95826 96192 96568 96963 97385 97845 98367 98991 From this table, when the specific gra- vity of any spirituous liquor is ascertained, it will be easy to find the quantity of rec- tified spirit of the above-mentioned stand- ard, contained in any given quantity of it, either by weight or measure. Dr. Blagden concludes this part of the report with observing, that as the experi- ments were made with pure spirit and wa- ter, if any extraneous substances are con- tained in the liquor to be tried, the speci- fic gravity in the tables will not give ex- actly the proportions of water and spirit in it. The substances likely to be found in spirituous liquors, wher no fraud is suspected, are essential oils, sometimes empyreumatic, miio^aginous or extrac- tive 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 near- ly of the same specific gravity as spirit, in general rather lighter, and therefore, not- withstanding the mutual penetration, will probably make little change in the speci- fic gravity of any spirituous liquor in which they are dissolved. The other substances are all heavier than spirit ; the specific 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 entertained of endeavouring to determine this matter with some preci- sion; and accordingly Dr. Dollfuss evapo- cimal by six nearly, equal to what would indicate in the above-mentioned mixture, about one-seventh of a grain of water more than the truth, to 100 of spirit ; a quantity much too minute for the consideration of government. * 'I he strength of spirits is determined, according to the existing laws, by Sikes* hydrometer ; but as many dealers use Di- cas's, I shall describe it here, and the for- mer under DISTII I.ATION. It consists of a light copper ball, termi- nating below with a ballast bottom, and above with a thin stem, divided into ten parts. The upper extremity of the stem is pointed, to receive the little brass poi- ses, or discs, having each a hole in its cen- tre. 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 hydro- meter, to make the correction for tempe- rature. The first thing in using this in- strument is to plunge the thermometer into a glass cylinder containing the spirits to be tried. The sliding rule has then the degree of temperature indicated, moved opposite to zero. The hydrome- ter 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 rated 1000 grains of brandy, and the same gallons of that spirit would require to have dty of rum, to dryness; the former 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 con- tain too little water, by 10 gallons. When the thermometer degree of 60 is put op- posite to zero, then the weights and value of the spirits have the following 1 relations on this scale. quantity left a residuum of 40 grains, the latter only of 8| grains. The 40 grains of residuum from the brandy, dissolved again in a mix- ture of 100 of spirit, with 50 of water, in- creased its specific gravity .00041 ; hence the effect of this extraneous matter upon the specific gravity of the brandy contain- ing it, would be to increase the fifth de- ALC ALC 102.5 denotes 20 under proof 122.0 10 143.5 Proof 167. 10 over proof 193. 20 221. 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 percent, 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 60 Fahr. 1 find that 10 over proof on Dicas corresponds to Specific gravity 0.9085 3 over proof to 0.9169 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 corresponds to 48 alcohol of 0.791 at the temperature of 68, united to 52 of water, and cooled down to 60. Equal weights of that strong alcohol and water, give, at 60, a specific gravity of 0.9175. By the Act of Parliament of 1762, the spe- cific gravity of proof was fixed at 0.916. It is at present to water as 12 to 13, or -= 0.923. See DISTILLATION.* The most remarkable characteristic pro- perty of alcohol, is its solubility or combi- nation in all proportions with water ; a property possessed by no other combus- tible substance, * except the acetic spirit obtained by distilling the dry acetates.* When it is burned in a chimney which communicates with the worm-pipe of a distilling apparatus, the product, which is condensed, is found to consist of water, which exceeds the spirit in weight about one-eighth part; *or more accurately, 100 parts of alcohol, by combustion, yield 136 of water.* If alcohol be burned in closed vessels with vital air, the product is found to be water and carbonic acid. Whence it is inferred that alcohol con- sists of hydrogen, united either to carbo- nic acid or its acidifiable base; and that the oxygen uniting on the one part with the hydrogen, 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 proportions, it consists of 13.8 water, and 86.2 of absolute alcohol. The vapour of alcohol was made to traverse a narrow porcelain tube ignited, from which the products passed along a glass tube about six feet in length, refrigerated by ice. A little charcoal was deposited in the porcelain, and a trace of oil in the glass tube. The resulting gas being ana- lyzed in an exploding eudiometer, with oxygen, was found to resolve itself into carbonic acid and water. Three volumes of oxygen disappeared for every two vo- lumes of carbonic acid produced ; a pro- portion which obtains, in the analysis by oxygenation of olefiant gas. Now, as nothing resulted but a combustible gas of this peculiar constitution, and condensed water equal to ^454 of the original weight of the alcohol, we may conclude, that va- pour 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 ab- solute 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 0.97804 Of aqueous vapour is 0.62500 Sum =. 1.60304 And alcoholic vapour is = 1.6133 These numbers approach nearly to those which would result from two prime equi- valents of olefiant gas, combined with one of water; or ultimately, three of hydro- gen, two of carbon, and one of oxygen.* A considerable number of the uses of this fluid as a menstruum, will pass under our observation in the various articles of this work. The mutual action between alcohol and acids produces a light, vola- tile, and inflammable oil, called ether. See ETHER. Pure alkalis unite with spirit of wine, and form alkaline 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 ex- ists 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 surprise those who are unacquainted with chemical effects. If, for example, a saturated solution of nitre in water be ta- ken, and an equal quantity of strong spi- rit 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 crystals. The degrees of solubility of many neu- tral salts in alcohol have been ascertained by experiments made by Macquer, of which an account is published in the Me- ALC ALC moirs of the Turin Academy, The alco- hol he employed was carefully freed from superabundant water by repeated rectifi- cations, without addition of any interme- diate substance. The salts employed in his experiments were previously deprived of their water of crystallization by a care- ful drying 1 . He poured into a matrass, upon each of the salts thus prepared, half an ounce of his alcohol, and set the mat- rass in a sand-bath. When the spirit be- gan to boil, he filtrated it while it was hot, Qitantity Salts soluble in ef grains. 200 grains oj 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 48 Muriate of copper and left it to cool, that he might observe the crystallizations which took place. He then evaporated the spirit, and weighed the saline residuutns. He repeated these experiments a second time, with this dif- ference, that instead of evaporating 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. Peculiar phenomena of the fame. 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. C Larger, more luminous, red and decrepitat- C .ing- 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 re- flections, not easily capable of abridg- ment. * The alcohol he employed in the above experiments had a specific gravity of 0.840. In analytical researches, alcohol affords frequently a valuable agent for separating salts from each other. We shall there- fore introduce the following additional table, derived chiefly from the experi- ments of Wenzel ; 100 parts of alcohol dissolve of Temp. Succinic acid, Acetate of soda, Nitrate of silver, Refined sugar, Boracic acid, Nitrate of soda, Acetate of copper, Muriate of ammonia, 74.0 parts 46.5 41.7 24.6 20.0 9.6 7.5 7.1 Nitrate of Cobalt at 54.5 100 Copper 54.5 100 Alumina 54.5 100 Lime 125 Magnesia 180.5 290 Muriate of Zinc 54.5 100 Alumina 54.5 100 Magnesia 180.5 547 Iron 180.5 100 Copper Acetate of Lead 180.5 154.5 100 100 At the boiling point, 100 parts of alco- hol dissolve of muriate of lime 100 parts Nitrate of ammonia, 89 Corrosive sublimate, 88.8 Superarseniate of potash, 3.75 Oxalate of potash, - 2.92 Nitrate of potash, - 2.08 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 Kir- wan, that dried muriate of magnesia dis- solves more abundantly in strong than in weak alcohol. 100 parts of specific gravi- ty 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 so- luble 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 Q . All deliquescent salts are soluble in al- ALC ALC cohol. Alcohol holding the strontitic salts in solution, gives a flame of a rich purple. The cupreous salts and boracic acid give a green ; the soluble calcareous, a reddish; the barytic, a yellowish. 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 Edin- burgh Encyclopaedia, article Cold, an ac- count of his having succeeded in solidify- ing it by a cold of 110. The alcohol he employed had a density of 0.798 at 60 P . His process has been kept secret. The boiling point of alcohol of 0.825 is 176, Alcohol of 0.810 boils at 173.5. For the force of its vapour at different tempera- tures, and its specific heat, see VAPOUR. M. Gay-Lussac having shown that this liquid is a compound of olefiant gas and water, potassium ought to disengage from it, hydrogen and olefiant gas. In the absolute alcohol of Richter there is no water, independent of that which is essential to its constitution. See FERMEN- TATION. When chlorine is made to pass through alcohol in a WouhVs apparatus, there is a mutual action. Water, an oily looking substance, muriatic acid, a little carbonic acid, and carbonaceous matter, are the products. This oily substance does not redden turnsole, though its analysis by heat shows it to contain muriatic acid. It is white, denser than water, has a cooling taste analogous to mint, and a peculiar, but not ethereous odour. It is very solu- ble in alcohol, but scarcely in water. The strongest alkalis hardly operate on it. It was at one time maintained, that al- cohol did not exist in wines, but was ge- nerated and evolved by the heat of distil- lation. 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 subcarbonate of potash. The alcohol immediately sepa- rated and floated on the top. He distilled another portion of wine in vacuo, at 59 Fahr. a temperature considerably below that of fermentation. Alcohol came over. Mr. Brande proved the same position by saturating wine with subacetate of lead, and adding potash. MM. Adam and D up ortal have substitut- ed 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 n. series of four vessels, arranged like a Woulfe's apparatus. The last vessel com- municates with the worm of the first re- frigeratory, This, the body of the still and the two recipients nearest it, are charged with the wine or fermented li- quor. When ebullition takes place in the still, the vapour issuing from it communi- cates soon the boiling temperature 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 tbe first refri- geratory. The wine round the worm will likewise acquire heat, but more slowly. The vapour that in that event, may pass uncondensed through the first worm, is conducted into a second, surrounded with cold water. Whenever the still is worked off, it is replenished by a stop-cock 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 tem- perature, 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 ex- cellent, from the first. Several stills on the above principle have been constructed at Glasgow for the West India distillers, and have been found extremely advanta- geous. The excise laws do not permit their employment in the home trade.* If sulphur in sublimation meet with the vapour of alcohol, a very small portion combines with it, which communicates a hydrosulphurous 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 M. Favre has lately asserted, that, having di- gested two drams of flowers of sulphur 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 si- milar mixture left to stand for a month in a place exposed to the solar rays, afforded sixteen grains of precipitate ; and another, from which the light was excluded, gave thirteen grains. If alcohol be boiled with one-fourth of its weight of sulphur for an hour, and filtered hot, a small quantity of minute crystals will be deposited on cool- ing; and the clear fluid will assume an opaline hue on being diluted with an equal quantity of water, in which state it will pass the filter, nor will any sediment ALC ALK fee deposited for several hours. The al- eohol used in the last-mentioned experi- ment did not exceed .840. Phosphorus is sparingly soluble in alco- hol, but in greater quantity by heat than in cold. The addition of water to this solution affords an opaque milky fluid, which gradually becomes clear by the subsidence of the phosphorus. Earths seem to have scarcely any action upon alcohol. Quick-lime, however, pro- duces some alteration in this fluid, by changing its flavour and rendering it of a yellow colour. A small portion is proba- bly taken up. Soaps are dissolved with great facility in alcohol, with which they combine more readily than with water. None of the me- tals, 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 men- struum of one class of varnishes. See VARNISH. Camphor is not only extremely soluble in alcohol, but assists the solution of re- sins in it. Fixed oils, when rendered dry- ing by metallic oxides, are soluble in it, as well as when combined with alkalis. Wax, spermaceti, biliary calculi, urea, and all the animal substances of a resinous nature, are soluble in alcohol ; but it cur- dles milk, coagulates albumen, and har- dens the muscular fibre and coagulum of the blood. The uses of alcohol are various. As a solvent of resinous substances and essen- tial 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 alcohol dissolving the resinous parts, and the water the gum- my. From giving a steady heat without smoke when burnt in a lamp, it was for- merly much employed to keep water feoiling on the tea-table. In thermometers for measuring great degrees of cold, it is preferable to mercury, as we cannot bring it to freeze. It is in common use for pre- serving many anatomical preparations, and certain subjects of natural history ; but to some it is injurious, the molluscs for instance, the calcareous covering of which it in time corrodes. It is of con- siderable use too in chemical analysis, as appears under the different articles to which it is applicable. Trom the great expansive power of al- cohol, it has been made a question, whe- ther it might not be applied with advantage in the working of steam engines. From a series of experiments made by Betan- court, it appears, that the steam of alco- hol has, in all cases of equal temperature, more than double the force of that of wa- ter ; 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 expensive as to be an object of great im- pertance, 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 economical. 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 Visi. ALE. See BEER. ALEMBIC, or STILL. This part of che- mical apparatus, used for distilling or separating volatile products, by first rais- ing 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 LABORA- TORY. ALEM BROTH SALT. Corrosive muriate of mercury is rendered much more solu- ble in water, by the addition of muriate of ammonia. From this solution crystals are separated by cooling, which were called sal alembroth by the earlier chemists, and appeared to consist of ammonia, muriatic acid, and mercury. ALGAROTH (POWDER OF). Among the numerous preparations which the alchemi- cal researches into the nature of antimony have afforded, the powder of algaroth is one. When butter of antimony is thrown into water, it is not totally dissolved; but part of the metallic oxide falls down in the form of a white powder, which is the powder of algaroth. It is violently purga- tive and emetic in small doses of three or four grains. See ANTIMONY. ALKAHEST. The pretended universal solvent, or menstruum, of the ancient che- mists. Kunckel has very well shown the absurdity of searching for a universal sol- vent, by asking, " If it dissolve all substan- ces, in what vessels can it be contained?'* ALKALESCENT. Any substance in which alkaline properties are beginning to be developed, or to predominate, is termed alkalescent. The only alkali usually ob- served to be produced by spontaneous de- composition is the volatile ; and from their tendency to produce this, some spe- cies of vegetables, particularly the cruci- form, are styled alkalescent, as are some animal substances. See FERMENTATION (PUTRID). ALK ALK * AIKAII. 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 combination. When Lavoisier introduced oxygen as the acidifying- prin- ciple, Morveau proposed hydrogen as the alkalifying principle, from its being a con- stituent 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 combi- nation 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, com- bined with oxygen in one proportion, pro- duce a body possessed of alkaline proper- ties, in another proportion of acid proper* ties. And on the other hand, ammonia and prussic acid prove that both the alka- line and acid conditions can exist inde- pendent of oxygen. These observations 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 al- kalis is still increased, when we find a body sometimes performing the functions of an acid, sometimes of an alkali. Nor can we diminish this difficulty 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 wished to define the alkalis by bringing into view their electric energy, it Would be neces- sary to compare them with the electric energy which is opposite to them. Thus we are always reduced to define alkalini- ty by the property which it has of saturat- ing acidity, because alkalinity and acidity are two correlative and inseparable terms. M. Gay-Lussac conceives the alkalinity which the metallic oxides enjoy to be the result of two opposite properties, the al- kalifying property of the metal^ and the acidifying of oxygen, modified both by the combination and by the proportions. The alkalis may be arranged into three classes : 1st, 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. ammonia. 3d, Those containing oxy- gen, hydrogen, and carbon. In this class we Vot. r, [19-] have aconlta, atropia, brucia, cicuta, daturrt delphia, hyosciama, morphia, strychnia* and perhaps some other truly vegetable alkalis. The order of vegetable alkalis may be as numerous as that of vegetable acids. The earths, lime, barytes, and strontites were enrolled among the alka- lis by Fourcroy ; but they have been kept apart by other systematic writers, and are called alkaline earths. Besides neutralizing acidity, and there- by giving birth to salts, the first four alka- lis 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 vege- table colours after being saturated with carbonic acid, by which criterion they are distinguishable from the alkaline earths. 3d^ They have an acrid and urinous taste. 4th, They are powerful solvents 1 or cor- rosives of animal matter ; with which, as well as with oils in general, they combine, so as to produce neutrality. 5th, They are decomposed, or volati- lized, at a strong red heat. 6th, They combine with water in every proportion, and also largely with alcohol. 7th, They continue to be soluble in water when neutralized with carbonic acid ; while the alkaline earths thus be- come insoluble. It is needless to detail at. length Dr. Murray's speculations on alkalinity. They seem to flow from a partial view of che- mical phenomena. According to him, either oxygen or hydrogen may generate alkalinity, but the combination of both principles is necessary to give this condi- tion its utmost energy. " Thus the class of alkalis will exhibit the same relations as the class of acids. Some are compounds of a base with oxygen ; such are the greater number of the metallic oxides, and probably of the earths. Ammonia is a compound of a base with hydrogen. Pot- ash, soda, barytes, strontites, and proba- bly lime, are compounds 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 pow- er to the same bodies after they are slack- ed 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. Mur- ray's strongest lime, that is the hydrate,- are required s to produce the same alktf- ALK ALL line effect. If we ignite nitrate of barytes, we obtain, as is well known, a perfectly dry barytes, or protoxide of barium; but if we ignite crystallized barytes, we ob- tain the same alkaline earth combined with a prime equivalent of water. These two different states of barytes were de- monstrated by M. Berthollet in an excel- lent 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 substance which diminish- es its action on other bodies, whicn ren- ders it more fusible, and which gives it by fusion the appearance of glass. This sub- stance is nothing 1 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 pro- perties of the first " Page 47. 100 parts of barytes void of hydrogen, or dry bary- tes, neutralize 28J of dry carbonic acid. "Whereas 11 1| parts of the hydrate, or what Dr. Murray has styled the most en- ergetic, 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 wa- ter. The proof of this is, that when car- bonic acid and that hydrate unite, the ex- act quantity of water is disengaged. The protoxide of barium, or pure barytes, has never been combined with hydrogen by any chemist.* ALKALI (PHLOGISTICATED, or PJIUSSIAW.) When a fixed alkali is ignited with bul- lock's blood, or other animal substances, and lixiviated, it is found to be in a great measure saturated with the prussic acid : from the theories formerly adopted re- specting this combination, it was distin- guished by the name of phlogisticated al- kali. See ACID (Pnussic.) ALKALI (VOLATILE.) See AMMONIA. * ALKALI MET EH. The name first given by M. Descroizilles to an instrument or measure of his graduation, for determining the quantity of alkali in commercial pot- ash and soda, by the quantity of dilute sul- phuric acid of a known strength which a certain weight of them could neutralize. His method was unnecessarily operose. A much simpler, and very accurate mode, was exhibited by Dr. Ure before the Li- nen Board of Dublin in June 1816, and soon afterwards submitted in manuscript to Dr. Henry, who has since then expung- ed the description of M. Descroizilles' al- kalimeter from his valuable elements, and substituted one on Dr. Ure's principle. More recently Dr. Ure has been occupied in completing the arrangement of an in- strument for giving increased facility and dispatch to chemical analysis in general. It will apply to alkalis, acids, earths, me- tals, 8cc. He hopes to be able, very soon, to submit its construction and performance to the tribunal of the public. Meanwhile directions will be given in this work under the individual alkalis, for ascertaining the quality of commercial specimens.* ALKANET. The alkanet plant is a kind of bugloss, which is a native of the warm- er parts of Europe, and cultivated in some of our gardens. The greatest quantities are raised in Germany and France, parti- cularly 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 sub- stances. The aqueous tincture is of a dull brownish colour ; as is likewise the spiri- tuous tincture when inspissated to the con- sistence 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.f 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. * ALLANITE. A mineral first recognized as a distinct species by Mr. Allan, of Edin- burgh, to whose accurate knowledge, and splendid collection, the science of mine- ralogy has been so much indebted in Scot- land. Its analysis and description, by Dr. Thomson, were published in the 6th vo- lume of the Edinburgh Ph. Trans. M. Giesecke found it in a granite rock in West Greenland. It is massive and of a brownish black colour. External lustre, dull; internal, shining and resinous frac- ture small conchoidal opaque greenish gray streak scratches glass and horn- blende brittle spec. -grav. 35 to 4.O.. Froths and melts imperfectly before the f On making an infusion of alkanet roots in alcohol, I was surprised to find the co- lour a deep blue, instead of being red. Remembering that the alcohol had stood over an alkali, I added some acid to the blue infusion. It became instantly red; and the same colour appeared to be pro- duced originally, when the roots were steeped in pure alcohol. 1 am surprised, that I have not met with any account of habitudes so interesting, and which ac- quire additional value, when contrasted with those of litmus and other vegetable colours, originally blue. These, redden- ed by an acid, are restored by an alkali ; while alkanet, made blue by alkalis, i. restored by acids. ALL ALL "blow-pipe, into a black scoria. It con- sists 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 gado- linite, but may be distinguished, from the thin fragments of the latter being trans- lucent 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, ap- proach very closely in their composition to allanite.* * ALLOCHROITE. A massive opaque mi- neral of a grayish, yellowish, or reddish colour. Quartz scratches it, but it strikes fire with steel. Jt has externally, a glis- tening, and internally, a glimmering lustre. Its fracture is uneven, and its fragments are translucent on the edges : sp. gr. 3.5 to 3.6. It melts before the blow-pipe into a black opaque enamel. Vauquelin's ana- lysis is the following : Silica 35, lime 30.5, oxide of iron 17, alumina 8, carbonate of lime 6, oxide of manganese 3.5, M. Brong- niart says it is absolutely infusible without addition, and that it requires a flux as phosphate of soda or ammonia. With these it passes through a beautiful grada- tion 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 re- pres'ents 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 sometimes brown garnets.* * AI.LOPHANE. A mineral of a blue, and sometimes a green or brown colour, which occurs massive, or in imitative shapes. Lustre vitreous; fracture imperfectly con- choidal; 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, carbonate of copper 3.06, hydrate of Iron 0.27, water 41.3. Stromeyer. It ge- latinizes in acids : It is found in a bed of ironshot limestone in gray wacke slate, in the forest of Thuringia, It was called Rie- xnannite. * AI.IAY, or ALT.OY. Where any precious 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 dimi- nishing the value of the precious metal. Philosophical chemists have availed them- selves of this term to distinguish all metal- lic compounds in general. Thus brass is railed 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 composi- tion, or which gives it its value. Thus English jewellery trinkets are ranked un- der alloys of gold, though most of them deserve to be placed under the head of copper. When mercury is one of the com- ponent metals, the alloy is called amalgam. Thus we have an amalgam of gold, silver, tin, &c. Since there are about 30 differ- ent 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 me- tals have so little affinity for others, that as yet no compound of them has been ef- fected, whatever pains have been taken. Most of these obstacles to alloying; arise from the difference in fusibility and vola- tility. Yet a few metals whose melting point is nearly the same, refuse to unite. It is obvious that two bodies will not com- bine, unless their affinity or reciprocal at- traction, be stronger than the cohesive at- traction of their individual particles. To overcome this cohesion of the solid bo- dies, and render affinity predominant, they must be penetrated by caloric. If one be very difficult effusion, and the other very volatile, they will not unite unless the re- ciprocal attraction be exceedingly strong. But if their degree of fusibility be almost the same, they are easily placed in the cir- cumstances most favourable for making an alloy. If we are therefore far from know- ing all the binary alloys which are possi- ble, we are still further removed from knowing all the triple, quadruple, &c. which may exist. It must be confessed, moreover, that this department of chemis- try has been imperfectly cultivated. Besides, alloys, are not, as far as we know, definitely regulated like oxides in the proportions 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 propor- tions. But 100 parts of mercury Mall unite with 1, 2, 3, or with any quantity up to a 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 me- tallic 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 con- ductors of electricity; crystallize more or less perfectly; some are brittle, others ductile and malleable; some have a pecu- liar odour; several are very sonorous and elastic. When an alloy consists of metals ALL ALL eLhTerently fusible, it is usually malleable while cold, but brittle while hot; as is ex- emplified in brass. The density of an alloy is sometimes greater, sometimes less than the mean density of its components, showing 1 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 1 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 fusi- ble metals, may often be decomposed, by exposing them to a temperature capable of melting only one of them. This opera- tion is called eliquation. It is practised on the great scale to extract silver from copper. The argentiferous copper is melt- ed 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 se- parately treated. Thus 3 of lead, and 1 of tin, at a dull red, burn visibly, and are almost instantly oxidized. Each by itself in the same circumstances, would oxidize slowly, and without the disengagement of light. The formation of an alloy must be regu- lated by the nature of the particular me- tals; 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 vola- tility, they unite, or with which they can after union be separated by heat. The greater or less tendency to separate into different proportional alloys, by long con- tinued fusion, may also give some informa- tion on this subject. Mr. Hatchett re- marked, in his admirable researches on metallic alloys, that gold made standard with the usual precautions by silver, cop- per, lead, antimony, &c. and then cast in- to vertical bars, was by no means a uni- form compound; but that the top of the bar, corresponding to the metal at the bot- tom of the crucible, contained the larger proportion of gold. Hence, for thorough combination, two red-hot crucibles should be employed; and the liquefied metals should be alternately poured from the one into the other. And to prevent unneces- sary oxidizement by exposure to air, the crucibles should contain, besides the me- tal, a mixture of common salt and pound- ed charcoal. The melted alloy should al- so be occasionally stirred up with a rod of pottery. The most direct evidence of a chemical change having taken place in the two me- tals by combination, is when the alloy melts at a much lower temperature than the fusing points of its components. Iron which is nearly infusible, 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 by mixture, as is exem- plified in the uncrystallizable residue of saline solutions, or mother waters, as they are called. Sometimes two metals will not directly unite, which yet, by the in- tervention 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 previously uniting the iron to tin or zinc, The tenacity of alloys is generally, though not always, inferior to the mean of the separate metals. One part of lead will destroy the compactness and tenacity of a thousand of gold. 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 be- comes brittle. In common cases, the specific gravity affords a good criterion whereby to judge of the proportion in an alloy, consisting of two metals of different densities. But a very fallacious rule has been given in some respectable works, for comparing the specific gravity that should result from , given quantities of two metals of known densities alloyed together, supposing no chemical penetration or expansion of vo- lume to take place. Thus it has been taught, that if gold and copper be united in equal weights, the computed or mathe- j matical specific gravity of the alloy is the j arithmetical mean of the two specific gra- ; vities. This error was pointed out by me j in a paper published in the 7th number of the Journal of Science and the Arts; and the correct rule was at the same 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 j weights by the sum of the volumes, com- pared to water, reckoned unity. Or in \ another form, the rule maybe stated thus : Multiply the sum of the weights into the product of the two specific gravities for a numerator, and multiply each specific gravity into the weight of the other body, ALM ALO and add the two products together for a denominator. The quotient obtained by dividing 1 the numerator by the denomina- tor, is the true computed mean specific gravity; and that found by experiment, being compared with it, will shew whe- ther expansion or condensation of volume has attended the chemical combination. Gold having a specific gravity of 19.36, and copper of 8.87, being alloyed in equal weights, give on the fallacious rule of the arithmetical mean of the densities, 19.36 4- 8.87 14.11; whereas the rightly calculated mean specific gravity is only 12.16. It is evident that by compar- ing the former number with chemical ex- periment, we should be led to infer a pro- digious condensation of volume beyond what really occurs. A circumstance was observed by Mr. Hatchett to influence the density of me- tals, which a priori might be thought un- important. 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 in- to the solid state under pressure, exert their cohesive attraction with adventitious strength ? Under the title metal, a tabular view of metallic combinations will be found, and under that of the particular metal, the requisite information about its alloys. ALLUVIAL FORMATIONS, in geology, are recent deposits in valleys or in plains, of the detritus of the neighbouring moun- tains. Gravel, loam, clay, sand, brown coal, wood coal, bog iron ore, and calc tuff, compose the alluvial deposites. The gravel and sand sometimes contain gold and tin, if the ores exist in the adjoining mountains. Petrified wood and animal skeletons are found in the alluvial clays and sand.* ALKOSDS. Almonds consist chiefly of w\ oil of the nature of fat oils, together with farinaceous matter. The oil is so plentiful, and so loosely combined or mix- ed with the other principles, that it is ob- tained 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 bit- irr almonds yield an oil as tasteless as that of the other, all the bitter matter remain- ing 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 dis- tillation. Rember obtained from them l-3d of watery extract, and 3-32ds of spiri- tuous. Bitter almonds are poisonous to birds, and to some animals. A water dis- tilled from them, when made of a certain degree of strength, has been found from experiment to be poisonous to brutes; and there are instances of cordial spirits impregnated with them being poisonous to men. It seems, indeed, that the vege- table principle of bitterness in almonds and the kernels of other fruits, is destruc- tive to animal life, when separated by dis- tillation from the oil and farinaceous mat- ter. The distilled water from laurel leaves appears to be of this nature, and its poi- sonous effects are well known. Sweet almonds are made into an emul- sion by trituration with water, which on standing separates a thick cream floating on the top. The emulsion may be cur- dled by heat, or the addition of alcohol or acids. The whey contains gum, extractive matter, and sugar, according to Professor Proust ; and the curd, when washed and dried, yields oil by expression, and after- wards by distillation the same products as cheese. The whey is a good diluent. * Prussic or hydrocyanic acid is the de- leterious ingredient in bitter almonds. The best remedy after emetics is a com- bination of sulphate of iron with bicarbo- nate of potash.* ALOES. This is a bitter juice, extracted from the leaves of a plant of the same name. Three sorts of aloes are distin- guished in the shops by the names of aloe socotrina, aloe hepatica, and aloe caballina. The first denomination, which is applied to the purest kind, is taken from the island of Zocotora ; the second, 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 in- stances from different species of the same plant. It is certain, however, that the dif- ferent kinds are all prepared at Morviedro in Spain, from the same leaves of the com- mon aloe. Deep incisions are made in the leaves, from which the juice is suffered to flow ; and this, after decantation from its sediment, and inspissation in the sun, is exposed to sale in leathern bags by the name of socotrine 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 ALU ALU 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 un- pleasant peculiar smell, which cannot be described, and an extremely bitter taste. Aloes appears to be an intimate combi- nation of gummy resinous matter, so well blended together, that watery or spiri- tuous solvents, separately applied, dissolve the greater part of both. It is not deter- mined 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 resinous which Vauquelin has found in many febrifuge barks. The recent juice of the leaves absorbs oxygen, and be- comes a fine reddish purple pigment.* ALUDKL. The process of sublimation differs from distillation in the nature of its product, which, instead of becoming con- densed 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 chim- neys, 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 hav- ing no nose or beak, and in the other cir- cumstances here mentioned, were called aludels. They are seldom now to be seen in chemical laboratories, because the op- erations of this art maybe performed with greater simplicity of instruments, provi- ded attention be paid to the heat and other circumstances. * ALUM. See ALUMINA, Sulphate of.* * ALUM-EAHTH. A massive mineral, of a blackish brown colour, a dull lustre, an earthy and somewhat slaty fracture, sec- tile, and rather soft. By Klaproth's analy- sis it contains, charcoal 19.65, silica 40, alumina 16, oxide of iron 6.4, sulphur 2.84, sulphates of lime and potash, each 1.5, sul- phate of iron 1.8, magnesia and muriate of potash 0.5, and water 10.75. * ALUM-SLATE. 1. Common. This mine- ral occurs both massive and in insulated balls, of a grayish black colour, dull lus- tre, straight slaty fracture, tabular frag- ments, streak coloured like itself; though, soft it is not very brittle. Effloresces, ac- quiring the taste of alum. 2. Glossy Alum-slate. A massive mine- ral 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 aug- mented by the formation of a saline efflo- rescence, which separates its thinnest plates. These afterwards exfoliate in brit- tle sections, causing entire disintegration.* * ALUMINA. One of the primitive earths, which, as constituting the plastic princi- ple of all clays, loams and boles, was cal- led argil orthe argillaceous earth; but now, as being obtained in greatest purity from alum, is styled alumina. It was deemed elementary matter till Sir H. Davy's cele- brated 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 re- garded 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 sul- phuric acid of the alum, and the earthy basis of the latter is separated in a white spongy precipitate. This must be thrown on a filter, washed, or edulcorated as the old chemists expressed it, by repeated af- fusions of water, and then dried. Or if an alum, made with ammonia instead of pot- ash, as is the case with some French alums, can be got, simple ignition dissi- pates its acid and alkaline constituents, leaving pure alumina. Alumina prepared by the first process is white, pulverulent, soft to the touch, ad- heres to the tongue, forms a smooth paste without grittiness in the mouth, insipid, inodorous, produces no change in vege- table colours, insoluble in water, but mix- es with it readily in every proportion, and retains a small quantity with con- siderable force ; is infusible in the strong- ALU ALU est heat of a furnace, experiencing mere- ly a condensation of volume and conse- quent hardness, but it is in small quanti- ties melted by the oxy-hydrogen blow- pipe. Its specific gravity is 2.000, in the state of powder, but by ignition it is aug- mented. Every analogy leads to the belief that alumina contains a peculiar metal, which may be called aluminum. The first evi- dences obtained of this position are pre- sented in Sir H. Davy's researches. Iron negatively electrified by a very high pow- er being fused in contact with pure alu- mina, 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, de- composed by an alkali, afforded alumina and oxide of iron. By passing potassium in vapour through alumina heated to whiteness, the greatest part of the potas- sium became converted into potash, which formed a coherent mass with that part of the alumina not decompounded; and in this mass there were numerous gray par- ticles, having the metallic lustre, and which became white when heated in the air, and which slowly effervesced in wa- ter. In a similar experiment made by the same illustrious chemist, a strong red heat only being applied to the alumina, a mass was obtained, which took fire spon- taneously by exposure to air, and which effervesced violently in water. This mass was probably an alloy of aluminum and potassium. The conversion of potassium into its deutoxide, dry potash, by alumina, proves the presence of oxygen in the lat- ter. 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 + 2.2 =*= 3.2. But Berzelius's analysis of sulphate of alumina seems to indicate 2.136 as the quantity of the earth which combines with 5. of the acid. Hence aluminum will come to b represented by 2.136 1. = 1.136. But we shall presently show that his ana- lysis, both of alum and sulphate of alumi- na, may be reconciled to Sir. H. Davy's equivalent prime == 3.2. That of alumi- num 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 Erecipitated. In this state it is called a ydrate, for when dried in a steam-heat it retains much water; and therefore re- sembles in composition wavellite, a beau- tiful mineral, consisting almost 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 fuller'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 wa- ter, and their solutions have a sweetish acerb taste. 2. Ammonia throws down their earthy base, even though they have been previ- ously acidulated with muriatic acid. 3. At a strong red heat they give out a portion of their acid. 4. Phosphate of ammonia gives a white precipitate. 5. H) driodate of potash produces a floc- culent precipitate of a white colour, pass- ing into a permanent yellow. 6. They are not affected by oxalate of ammonia, tartaric acid, ferroprussiate of potash, or tincture of galls ; by the first two tests they are distinguished 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. Jlcetate ofJllumina. 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 ace- tate of lime, having a specific gravity of about 1.050 ; a gallon of which, equivalent to nearly half a pound avoirdupois of dry acetic acid, is employed for every 2f lt>. 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 equivalent 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 observa- tions on the solutions of this salt Even when made with cold saturated solutions of alum and acetate of lead, and conse- quently but little concentrated, it be- comes turbid when heated to 122 Fahr. ; and at a boiling heat a precipitate falls of about one-half of the whole salt. On cool- ing, it is redissolved. This decomposition by heat, which would be prejudicial to the calico printer, is prevented by the excess ALti ALU of alum, which is properly used in actual practice. M. Gay-Lussac thinks this phe- nomenon has considerable analogy, with the coagulation of albumen by heat ; the particles of the water, and of the solid mat- ter, being 1 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 1 the crys- tals. Wenzel's analysis of acetate of alu- mina 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 -f- 6.4 artb, or 75.8 -f- 24.2 = 100. As alum contains, in round numbers, about 1.9th of earthy base, 8 oz. of real acetic acid present in the gallon of the redistilled pyrolignous, would require about 2J Ibs. of alum, for exact decomposition. The excess employ- ed is found to be useful. The affinity between the constituents of this salt is very feeble. Hence the at- traction of cotton fibre for alumina, aided by a moderate heat, is sufficient to decom- pose it. The following salts of alumina are in- soluble in water.- Arseniate, borate, phos- phate, tungstate, mellate, saclactate, lith- ate, malate, camphorate. The oxalate is un- erystallizable. It consists of 56 acid and water, and 44 alumina. The tartrate does not crystallize. But the tartrate of potash and alumina is remarkable, according to Thenard, for yielding no precipitate, either by alkalis or alkaline carbonates. The supergallate crystallizes. There seems to be no dry carbonate. A super- nitrate exists very difficult to crystallize. Its specific gravity is 1.645. A moderate heat drives off the acid. The muriate is easily made by digesting muriatic acid on gelatinous alumina. It is colourless, astrin- gent, deliquescent, uncrystallizable, red- dens turnsole, and forms a gelatinous mass by evaporation. Alcohol dissolves at 60 half its weight of this salt. A dull red lieat 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 ea- sily made, by digesting sulphuric acid on pure clay. The salt thus fanned crystalli- zes in thin soft plates, having a pearly lus- tre. It has an astringent taste, and is so soluble in water as to crystallize with dif- ficulty. When moderately heated the wa- ter escapes, and, at a higher temperature, the acid. Berzelius has chosen this salt for the purpose of determining the equi- valent 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, oxygeir be- ing reckoned 10, if we consider it a com- pound of a prime 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 preferring 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 compo- sition.* It is produced, but in a very small quantity, in the native state ; and this is mixed with heterogeneous matters. It ef- floresces in various forms upon ores dur- ing calcination, but it seldom occurs crys- tallized. The greater part of this salt is factitious, being extracted from various minerals called alum ores, such as, 1. Sul- phuretted clay. This constitutes the pu- rest of all aluminous ores, namely, that of la Tolfa, near Civita Vecchia, in Italy. It is white, compact, and as hard as indurat- ed clay, whence it is called petra alumina" ris. It is tasteless and mealy ; one hun- dred parts of this ore contain above forty of sulphur and fifty of clay, a small quan- tity of potash, and a little iron. Bergmann says it contains forty -three of sulphur in one hundred, thirty -five of clay, and twen- ty two of siliceous earth. This ore is first torrefied to acidify the sulphur, 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 py- rites are decomposed, and the alum "is formed. The alum ores of Hesse and Liege are of this kind ; but they are first torre- fied, which is said to be a disadvantageous method. 3. The schistus aluvninaris contains a variable proportion of petroleum and py- rites intimately mixed witli it. When the last are in a very large quantity, this ore is rejected as containing too much iron. Professor Bergmann very properly sug- gested, 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 spe- cies. 4. Volcanic aluminous ore. Such is that of Solfaterra near Naples. It is in the form of a white saline earth, after it has ef- floresced 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 shistus, impregnat- ed with so much oily matter, or bitumen, as to be. inflammable. It is found in Swc- ALU ALU ien, and also in the coal mines at White- haven, and elsewhere. Chaptai lias fabricated alum on a large scale from its component parts. For this purpose he constructed a chamber 9ifeet long 1 , 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, thfe joints of which overlap those of the first, and instead of mortar the bricks are joined with a cement of equal parts of pitch, tur- pentine, and wax, which, after having loeen boiled till it ceases to swell, is used hot. The roof is of wood, but the beams are very close together, and grooved length- wise, the intermediate space being filled up by planks fitted into the grooves, so that the whole is put together without a nail. Lastly, the whole of the inside is covered with three or four successive coating's 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 fragments 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 inti- mately penetrated by the acid, and is then lixiviated and crystallized in the usual manner. The cement answers the pur- pose of lead on this occasion very effec- tually, and accordingly to M. Chaptai, costs no more than lead would at three farthings a-pound. Curaudau has lately recommended a process for making alum without evapo- ration. One hundred parts of clay and five of muriate of soda are kneaded into a paste witli water, and formed into loaves. With these a reverberatory furnace is filled, and a brisk fire is kept up for two hours. Be- ing powdered, and put into a sound cask, one-fourth of their weight of sulphuric acid is poured over them by degrees, stirring the mixture well at each addition. As soon as the muriatic gas is dissipated, a quantity .of water equal to the acid is added, and the mixture stirred as before. When the heat is abated, a little more wa- ter is poured in, and this is repeated till eight or ten times as much water as there Veu. il { 20 ] 'fras 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 sedi- ment. The two liquors being mixed, % solution of potash is added to ihern, the alkali in which is equal to one-fourth of the weight of the sulphuric acid. Sul- phate of potash may be used, but twice as much of this as of the alkali is necessary. After a certain time the liquor by cooling affords crystals of alum equal to three times the weight of the acid used. It is refined by dissolving it in the smallest pos- sible quantity of boiling water. The re- sidue 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 prusr sian blue. This mode of making alum is particularly advantageous to the manufac- turers of prussian blue, as they may calcine their clay at the same time with their ani mal matters, without additional expense ; they will have no need in this case to add potash ; and the presence of iron, instead of being injurious, will be very useful. If they wished to make alum for sale, they might use the solution of sulphate of pot- ash, arising from the washing of their prus- sian blue, instead of water, to dissolve the combination of alumina and sulphuric acid. The residuums of distillers of aquafortis are applicable to the same purposes, as they contain the alumina and potash re- quisite, and only require to be reduced to powder, sprinkled with sulphuric acid, and lixiviated with water, in the manner directed above. The mother waters of these alums are also useful in the fabrica- tion of prussian blue. As the residuum of aquafortis contains an over-proportion of potash, it will be found of advantage to add an eighth of its weight of clay calcin- ed as above. * The most extensive alum manufacto- ry in Great Britain is at Hurlett, near Pais- ley, on the estate of the Earl of Glasgow. The next in magnitude is at Whitby ; of whose state and processes an instructive account was published by Mr. Winter, in the 25th volume of Nicholson's Journal. The stratum of aluminous 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 gene- rally found disposed in horizontal lamina:. 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 limes more valuable than the same bulk, 100 feet below. IT a quantity of the sdhistus be laid in a ALU ALU 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 gray. Its specific 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 vards one cubic yard of the schistose rock, is about sixpence- halfpenny. A man can earn from 2s. 6d. to 3s. a-day. The rock, broken into small pieces, is laid on a horizontal bed of fuel, composed of brushwood, &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 until the calcined heap be raised to the height of 90 or 100 feet. Its horizontal area has also been progressive- ly 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 plastering up the crevices with small schist moistened. Notwithstanding of this precaution, a great deal of sulphuric or sulphurous acid is dissipated. 130 tons of calcined sciiist produce on an average 1 ton of alum. This result has been de- ducedfrom an average of 150,000 tons. The calcined mineral is digested in wa- ter 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 be- comes .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 concentra- ted 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 manufacturer, or crude and compound from the soap-boiler, is added. The quantity of muriate neces- sary is determined by a previous experi- ment in a basin, and is regulated for the workmen by the hydrometer. By this addition, the pan liquor, which had ac- quired a specific gravity 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, instead of crystallizing, would, when it cools, pre- sent 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 wa- ters are drained off, to be pumped into the pans on the succeeding day. The crys- tals of alum are washed in a tub, and drain- ed. They are then put into a lead pan, with as much water as will make a satu- rated solution at the boiling point. V\ hen- ever 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 exteriorily in a solid cake, but in the interior cavity, in large pyramidal crystals, consisting of oc- tahedrons, inserted successively into one another. This last process is called roch- ing. Mr. Winter says, that 22 tons of mu- riate of potash will produce 100 tons of alum, to which 31 tons of the black ashes of the soap-boiler, or 7 . ; of kelp, are equi- valent. Where much iron exists in the alum ore, the alkaline muriate, by its de- composition, gives birth to an uncrystalli- zable muriate of iron. The alum manu- factured in the preceding mode is a super- sulphate of alumina and potash. There is another alum which exactly resembles it. This is a supersulphate of alumina and am- monia. Both crystallize in regular oc ahe- drons, formed by two four-sided pyramids joined base to base. Alum has an asirin- gent 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 t* air, but the interior remains long unchang- ed. Its water of crystallization is suffi- cient 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 cal- cined alum, and is used by surgeons as a mild escharotic. A violent heat separates a great portion of its acid. Alum thus was 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 preci- pitated by muriate of barytes ; the sul- phate 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. Alu- mina, well washed and burnt, equivalent to 10.67 per cent, was obtained, in ano- ther experiment, 10.86 per cent, resulted. 3d, Ten parts of alum dissolved in water, were digested with carbonate of strontites, till the earth was completely separated. ALU 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, 1L->.15 "Water, - - - - 45.00 100.00 Thenard's analysis, Ann. de Chimie, vol. 59. or Nicholson's Journal, vol. 18. cum- eides perfectly with tiiat of Beizelius in the product of sulphate of bary tes. From 490 parts of alum, he obtained 490 oi the ignited ban tic salt ; but the alumina was iu greater proportion, equal to 12.54 per cent, and the sulphate of potash less, or 15.7 in 100 parts. Dr. Thomson considers it as a com- pound of 3 atoms sulphate of alumina, 1 atom sulphate of potash, and "23 atoms water, as follows : Sulphate of alumina, 36.70 Sulphate of potash, 18.88 Water, - - - - 44.42 100.00 But Vauquelin, in his last anal} sis, 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 It deserves to be remarked, that the analysis of Professor Berzelius agrees with the supposition that alum contains, 4 sulphuric acid, = 20.0 34.36 2 alumina, => 6.4 11.00 1 potash, = 6.0 10.30 23 water, <*. 25.8 44.34 58.2 100.00 If we rectify Vauquelin's erroneous esti- mate of the sulphate of barytes, his analy- sis will also coincide with t ie 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 assump- tion of a prime of sulphate of potash. It is probable that all the aluminous salts have a similar constitution. It is to be ob- served, moreover, that the number 34. ;>6 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 bary- ALU tes, by a corrected analysis, which makei the prime of barytes 9.57. -Should ammonia be suspected in alum, {t may be detected, and its quantity esti- mated, by mixing quicklime with the sa- line solution, and exposing the mixture to heat in a retort, connected with a Woulfe'* apparatus. The water of ammonia being afterwards saturated with an acid, and evaporated to a dry salt, will indicate thfe quantity of pure ammonia in the alum. A variety of alum, containing both potash and ammonia, may also be found. This will occur where urine has been used, as well as muriate of potash, in its fabrica- tion. If any of these bisulphates of alu- mina and potash be acted on in a watery solution, by gelatinous alumina, a neutral triple salt i's formed, which precipitates in a nearly insoluble state. When alum in powder is mixed with flour or sugar, and calcined, it forms the pyrophorus of Homberg. Mr. Winter first mentioned, that another variety of alum can be made with soda, in- stead of potash. This salt, which crystal- lizes in octahedrons, has been also made with pure muriate of soda, and bisulphate of alumina, at the laboratory of Hurlett, by Mr. W. Wilson. It is extremely diffi- cult to form, and effloresces like the sul- phate of soda. The only injurious contamination of alum is sulphate of iron. It is detected by ferroprussiate of potash. To get rid of it cheaply, M. 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 advan- tageous mode of concentrating alum li- quors, as well as those of other salts, on the great scale, see EVAPORATION. Oxymuriate of alumina, or the chloride, has been proposed by Mr. Wilson of Dub- lin as preferable to solution of chlorine, for discharging the turkey -red dye. He prepares it by adding to a solution of oxy- muriate of lime, at asp. gravity of 1.060, a solution of alum of the sp. grav. 1 100, as long as any precipitate falls. The clear liquid is to be drawn off from the precipi- tate, and kept in close vessels. He says that it does not injure the cloth, nor annoy the the workmen, like the liquor of un- combined chlorine. Jinn, of Phil, vol, viii.* Alum is used in large quantities in many manufactories. When added to tallow, it renders it harder. Printer's cushions, and the blocks used in the calico manufactory, are rubbed with burnt alum to remove any g^reasiness, which might prevent the ink AMA AMB GTf colour from sticking 1 . Wood sufficient- ly soaked in a solution of alum does not asily 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 alum is useful in whitening silver, and silvering brass without heat. Alum mixed in milk helps the separation of its butter. If add- ed in a very small quantity to turbid wa- ter, in a few minutes it renders it perfect- ly limpid, without any bad taste or quali- ty ; while the sulphuric acid imparts to it a very sensible acidity, and does no^ pre- cipitate so soon, or so well, the opaque earthy mixtures that render it turbid, as 1 have often tried. It is used in making p\rophorus, in tanning and many other manufactories, particularly in the art of dyeing, in which it is of the greatest and most important use, by cleansing and opening the pores on the surface of the substance to be dyed, rendering it fit for receiving the colouring particles, (by which the alum is generally decompo- sed,) and at the same time making the co- lour fixed. Crayons generally consist of the earth of alum, finely powdered, and tinged for the purpose. In medicine it is employed as an astringent. * ALUMIXITK. 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 ad- here slightly to the tongue. Sp. gravity, 1.67. It consists of Sulphuric acid, 19.25 Alumina, 32.50 Water, 47.00 Silica, lime, and oxide of iron, 1.25 100.00 It may be represented very exactly by 2 primes of acid, 10 =20 5 alumina, 16 = 32 21 water, 23.6 Foreign matter, 0.4 47.2 0.8 50.0 100. The conversion of the above into alum is easily explained. When the three primes composing bisulphate of potash come into play, they displace precisely three primes (or atoms) of alumina. Two additional primes of water are also intro- duced at the same time, by the strong af- finity of the bisulphate for the particles of that liquid. The above alum ore is found chiefly in the alluvial strata round Halle in Sax- ony.* * AMADOU. It is a variety of the boletus igniarius, found on old ash and other trees. It is boiled in water to extract its soluble parts, then dried, and beat with a to loosen its texture. It has now the ap- pearance of very spongy doe-skin leather. It is lastly impregnated with a solution of nitre, and dried when it is called spunk, or German tinder ; a substance much used on the continent for lighting fire, either from the collision of flint and steel, or from the sudden condensation of air in the at- mospheric pyrophorus.* AMALGAM This name is applied to the combinations of mercury with other me- tallic substances. See MKRCURY. AMBER is a hard, brittle, tasteless sub- stance, sometimes perfectly transparent, but mostly semi-transparent or opaque, and of a glossy surface : it is found of all colours, but chiefly yellow or orange, and oft-en contains leaves or insects ; its speci- fic gravity is from 1.065 to 1.10U ; iis frac- ture is even, smooth, and glossy; it is ca- pable of a fine polish, and becomes elec- tric by friction ; when rubbed or heated, it gives a peculiar agreeable smell, par- ticularly when it melts, that is at 550 of Fahrenheit, but it then loses its transpa- rency ; projected on burning coals, it burns with a whitish flame, and a whitish, yellow smoke, but gives very little soot, and leaves brownish ashes ; it is insoluble in water and alcohol, though the latter, when highly rectified, extracts a reddish colour from it ; but it is soluble in the sul- phuric acid, which then acquires a reddish purple colour, and is precipitable from it by water; no other acid dissolves it, nor is i; soluble in essential or expressed oils, without some decomposition and long di- gestion ; but pure alkali dissolves it. By distillation it affords a small quantity of water, with a little acetous acid, an oil, and a peculiar acid. See ACID (Succi- ITIC). The oil rises at first colourless ; but, as the heat increases, becomes brown, thick, and empyreumatic. The oil may be rectified by successive distillations, or it may be obtained very light and lim- pid at once, if it be put into a glass alem- bic with water, as the elder Rouelle di- rects, 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 vessels it becomes brown by the action of light. Amber is met with plentifully in regu- lar mines in some parts of Prussia. The upper surface is composed of sund, under which is a stratum of loam, and under this a bed of wood, partly entire, but chiefly mouldered or changed into a bituminous substance. Under the wood is a stratum of sulphuric or rather aluminous mineral, in which the amber is found. Strong sul- phureous exhalations are often perceived in the pits. * Detached pieces are also found occa- sionally on. the sea-coast ja various coua., AMB AMB tries. It has been found in gravel becls near London. In the Itoyal Cabinet at Berlin there is a mass of 18 Ibs. weight, supposed to be the largest ever found. Jussieu asserts, that the delicate insects in amber, which prove the tranquillity of its formation, are not European. M. Hauy has pointed out the following 1 distinctions between mellite and copal, the bodies which most closely resemble amber. iMel- lite 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 par- ticles drop, they rebound from the plane which receives them. The origin of am- ber is at present involved in perfect ob- scurity, though the rapid progress of ve- getable chemistry promises soon to throw light on it. Various frauds are practised "with this substance. Neumann states as the common practices of workmen the two following: The one consists in surround- ing 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 boiling the amber about twenty hours with rapeseed 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 constituents are the same with those of vegetable bodies in general; viz. carbon, hydrogen, and oxygen ; but the proportions have not been ascertained. In the second volume of the Edinburgh Philosophical Journal, Dr. Brewster has given an account of some optical proper- ties of amber, from which he considers it established beyond a doubt that amber is an indurated vegetable juice ; and that the traces of a regular structure, indicated by its action upon polarized light, are not the effect of the ordinary laws of crystalliza- tion by which mellite has been formed, but are produced by the same causes which influence the mechanical condition of gum arabic, and other gums, which are known to be formed by the successive deposition and induration of vegetable fluids.* Amber is also used in varnishes. See VARXISH, and OIL of AMBER. AMBKRGUIS 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 sper- maceti 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 lit- tle too peremptorily affirmed it to be the cause of the morbid affection. As no large piece has ever been found without a grea- ter or less quantity of the beaks of the se- pia octopodia, the common food of the spermaceti whale, interspersed throughout its substance, there can be little doubt of its originating in the intestines of the whale; for if it were occasionally swallow- ed by it only, and then caused disease, it must much more frequently be found with- out these, when it is met with floating iu the sea, or thrown upon the shore. Ambergris is found of various sizes, ge- nerally 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 ex- posure to the air. Its specific gravity ranges from 780 to 926. If good, it ad- heres 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 odo- riferous 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, gray with black specks, or gray with yellow specks. Its smell is peculiar, and not easy to be counterfeited. At 144 it melts, and at 212 is volatilized in 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 fee- bly 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 dissolves a portion of it, and is of great use in analy- zing it, by separating its constituent parts. According to Bouillon la Grange- who has given the latest analysis of it, 3820 parts of ambergris consist of adipocere 2016 parts, a resinous substance 1167, benzoic acid 425, and coal 212. * But Bucholz could find no benzoic acid in it. Dr. Ure examined two different specimens with considerable attention. The one yielded benzoic acid, the other, equally genuine to all appearance, afforded none. See APIPOCERE and INTESTINAL CONCRETION. An alcoholic solution of ambergris, add- ed in minute quantity to lavender water, tooth powder, hair powder, wash balls, &c. communicates its peculiar fragrance. Its retail price being in London so high as a guinea per oz. leads to many adultera- tions. These consist of various mixtures of benzoin, labdanum, meal, &c. scented with musk. The greasy appearance and smell which heated ambergris exhibits, af- ford good criteria, joined to its solubility in hot ether and alcohol. * It has occasionally been employed in AMM AMM medicine, but its use is now confined ta the perfumer. Dr. Swediaur took thirty grains of it without perceiving any sensi- ble effect. A sailor, who took half an ounce of it, found it a good purgative. * AittBLYGOMTE. A greenish coloured mineral of different pale shades, marked on the surface with reddish and yellowish brown spots. It occurs massive and crys- tallized in oblique four-sided prisms. Lus- tre vitreous; cleavage parallel with the sides of an oblique four-sided prism of 106 10' and 77 53'; fracture uneven; fragments rhomb oidal ; translucent; hard- ness, as fe'dsj.ar; brittle; sp. gr. 3*0. In- tumesces with the blow-pipe, and fuses wit. i Ji reddish-yellow phosphorescence into a white enamel. It occurs in granite, along with green topaz and torn-inline, nea^ Pinig in Saxonv. It seems to be a species of spodumene.* AMKTHYST. 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 he blue. These ame- thysts have the same figure, hardness, spe- cific gravity, and other qualities, as the best sapphires or rubies, and come from the same laces, particularly from Persia, Arabia, Armenia, and the West Indies. The occidental amethysts are merely co- loured crystals or quartz. See QUARTZ and SAPPHIRK. AMIANTHUS, Mountain Flax. See As- BESTUS. * AMMONIA, called also Volatile Alkali. We shall first consider this substance in its purely scientific relations, and then de- tail its manufacture on the great scale, and its uses in the arts. There is a saline bo- dy, formerly brought from Egypt, where it" was separated from soot by sublimation, but which is now made abundantly in Eu- rope, called sal ammoniac. From this salt, pure ammonia can be readily obtain- ed by the following process: Mix nnslack- ed quicklime with its own weight of sal ammoniac, each in fine powder, and intro- duce them into a glass retort. Join to the beak of the retort, by a collar of caout- chouc, (a neck of an Indian rubber bottle answers well,) a glass tube about 18 inch- es long, containing pieces of ignited mu- riate of lime. This tube should lie in a horizontal position, and its free end, pre- viously bent obliquely by the blow-pipe, should dip into dry mercury in a pneuma- tic 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 f tfcs 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 containing 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 elasticity, 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. Now, as no aeriform body is more easily obtained in a pure state than ammonia, this diversity among accurate experimentalists, shows the nice- ty of this statical operation. MM. Biot and Arago make it = 0.59669 by experi- ment, and by calculation from its elemen- tary gases, they make it = 0.59438. Kir- wan says, that 100 cubic inches weigh 18.16 gr. at 30 inches of bar. and 61 u F., which compared to air reckoned 30.519, gives 0.59540. Sir H. Davy determine* its density to be = 0.590, with which esti- mate 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 spi- rits of hartshorn. An animal plunged into it speedily dies. It extinguishes combus- tion, but being itself to a certain degree combustible, the flame of a taper immers- ed in it, is enlarged before going out. 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. Jlmmoma. Water. 0.8750 32.50 67.50 0.8875 29.25 70.75 0.9000 26.00 74.00 0.9054 25.37 74.63 0.9166 22.07 77.93 0.9255 19.54 80.46 0.9326 17.52 82.48 0.9385 15.88 84.12 0.9435 14.53 85.47 0.9476 13.46 86.54 0.9513 12.40 87.60 0.9545 11.56 88.44 0.9573 10.82 89.18 0.9597 10.17 89.83 0.9619 9.60 90.40 0.9692 9.50 90.50 Water is capable of dissolving easily about one-third of its weight of ammonia- cal gas, or 460 times its bulk. Hence, when placed in contact with a tube filled with this gas, water rushes into it with ex- plosive velocity. Probably the quantity of ammonia stated in the above table is too ki^hby about one per cent. AMM AMM Br. Thomson states, in his System, vol. 2d. page 29. " \Vater, by my trials, is ca- pable of absorbing 780 times its bulk of this gas ; while, in the mean time, the bulk of the liquid increases from 6 to 10. The specific gravity of this solution is 0.900, which just accords with the increase of bulk." Correcting the first error where 6 is substituted tor 9, a less excusable error comes to be examined. Taking the Doc- tor's own number for the specific gravity of the gas, it is evident that 780 times the volume, combined with water, would give nearly 36 bv weight of gas in 100 of the liquid. But in the very same page he says, " It follows, from the experiments of Davy, that a saturated solution of ammo- nia is composed of 74.63 water and 25.37 ammonia." Hence, if that be correct, a liquid containing 36 per cent of ammonia is a manifest impossibility. In the very same page he gives Mr. Dalton's table, " which exhibits the quantity of ammonia contain- ed in ammoniacal solutions of different specific gravities." In this table, opposite to the specific gravity 0.90 of the liquid ammonia, such as he made in his own tri- als, we have 22.2, a far different quantity from the number 36 equivalent to his 780 volumes. Sir H. Davy's table differs very little from that of Mr. Dalton, the truth probably lying between them. It is cer- tain, indeed, that 100 parts of ammoniacal water, sp. gr. 0.900, instead of containing 36 pars, or 780 volumes, do not contain above 24 parts, or 520 volumes. Had Dr. Thomsom consulted Sir H. Davy's Ele- ments of Chemical Philosophy, he would have found the following statement, p. 268. " At the temperature of 50, under a pressure equal to 29.8 inches, water, I find, absorbs about 670 times its volume of gas, and becomes of specific gravity 0.875." In the table of Sir H. Davy, oppo- site 0.875, we have 32.5 per cent of am- monia. If any person will take the trouble of calculating, he will find that 670 inches of a gas, of which 100 cubic inches weigh 18 grs in combining with one cubic inch of water weighing '252.5 grains, form a so- lution that must contain just 32.3 per cent of the condensed gas. We thus perceive^ that liquid ammonia, as the aqueous compound is termed, may like spirits be very accurately valued by its specific gravity. But it dilfers remarka- bly from alcoholic mixtures in this respect, that the strongest ammoniacal liquor, when it is diluted with water, surfers no condensation of volume. The specific gravity of the dilute, is the mean of that of its components. Hence, having one point accurately, we can compute all be- low it, by paying attention to the rule given under SPECIFIC GHAVITT. To pro- cure aqueous ammonia, we may uge either a common still and refrigeratory o* a Woulte's apparatus. The latter should be preferred. Into a retort we put a mixture of two parts of slaked lime, and one part of [.ulverized sal ammoniac, and having connected the beak of the retort with the Woulfe's apparatus, containing pure wa- ter, we then disengage the ammonia, by the application of heat. When gas ceases to be evolved, the addition of a little hot water will renew its disengagement, and ensure complete decomposition of the salt. Since sal ammoniac contains nearly | its weight of ammonia, ten pounds of it should yield by economical treatment, 3Q pounds of liquid, whose specific gravity is 0.950, which is as strong as the ordinary purposes of chemistry and medicine re- quire ; and it will form twice that quanti- ty, or 60 pounds of the common water of ammonia, sold by apothecaries, which has rareh 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 present, it is instantly de- tected by its causing a milkiness in 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 in- genious paper by Dr. Henry. But the simplest, and perhaps most accurate mode of resolving ammonia into its elementary constituents, is that first practised by ML Berthollet, the celebrated discoverer of its composition. This consists in making 1 the pure gas traverse very slowly an igni- ted porcelain tube of a small diameter. The process, as lately repeated by M. Gay-Lussac, yielded from 100 cubic inches of ammonia, 2/0 cubic inches of consti- tuent gases ; of which by subsequent ana- lysis, 50 were found to be nitrogen, and 150 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 appears, by the most recent determina- tions, that the specific gravity of hydro- gen is 0.0694, compared to air as unity, and that of nitrogen, 0.9722. Three vo- lumes 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 experimen- tal 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 hy- drogen. To reduce ammonia to the sys- tem of equivalents, or to find its saturating ratio on that scale where oxygen repre- sents unity, we have this proportion 0.9722 : l."75 : : 1.1804 : 2.1*25, so that 2.125 may be called its prime equivalent. AMM AMM We shall find this number deduced from analysis, confirmed by the synthesis of all the ammoniacal salts. Dr. Front, in an able memoir on the relation between the specific gravities of g'aseous bodies and the weights of their atoms, published in the 6th vol. of the An- nals of Philosophy, makes the theoretical weight of the atom of ammonia to be only 1.9375 considering 1 it as a compound of 1 atom of azote, and li atoms of hydrogen. This statement appears to be a logical in- ference from Mr. Dalton's hypothesis of atomical combination. For water, the great groundwork of his atomic structure, is represented as a compound of one atom oxygen with one atom of hydrogen ; and this atomical unit of hydrogen consists of two volumes of the gas. Hence three vo- lumes of the gas must represent an atom and an half. But an atom is, by its very definition, indivisible. Dr. Front in the 38th number of the Annals, restores the true proportions of 3 atoms hydrogen, -f- 1 azote. Our doctrine of equivalent primes, resting on the basis of experimental induc- tion, claims no knowledge of the atomical constitution of bodies. The alkaline nature of ammonia is de- monstrated, 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 elec- tric power is applied to ammonia in its li- quid or solid combinations, simple decom- position is effected; but in contact with mercury, very mysterious phenomena oc- cur. Tf a globule of mercury be surround- ed with a little writer of ammonia, or pla- ced in a little cavity in a piece of sal am- moniac, and then subjected to the voltaic power by two wires, the negative touch- ing the mercury, and the positive the am- moniacal compound, the globule is instant- ly covered with a circulating film, a white smoke rises from it, and its volume en- larges, whilst it shoots out ramifications of a semi-solui consistence over the salt. The amalgam has the consistence of soft but- tsr, and may be cut with a knife. When- ever the electrization is suspended, the crab-like fibres retract towards the cen- tral 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 mer- Gttry, when a small globule is employed. Sir H. Davy, Berzelius, and MM. Gay- Lussac and Thenard, have studied this singular phenomenon with great care. They produced the very same substance by putting an amalgam of mercury and potassium into the moistened cupel of sal ammoniac. It becomes five or six times larger, assumes the consistence of buttery whilst it retains its metallic lustre. What takes place in these experiments ? In the second case, the substance of me- tallic aspect which we obtain is an ammo- niacal hydruret of mercury and potassium. There is formed, besides,' muriate of pot- ash. Consequently a portion of the po- tassium of the amalgam, decomposes the water, becomes potash, which itself de- composes the muriate of ammonia. Thence result hydrogen and ammonia, which, ia the nascent state, unite to the undecom- posed amalgam. In the first experiment, the substance, which, us in the second, presents the metallic aspect, is only an ammoniacal hydruret of mercury ; its for- mation is accompanied by the perceptible evolution of a certain quantity of chlorine at the positive pole. It is obvious, there- fore, that the salt is decomposed by the electricity. The hydrogen of the muria- tic acid, and the ammonia, both combine with the mercury. These hydrurets pos- sess the following properties. Their sp. gravity is in general below 3.0 ; exposed for some time to the tem- perature of 32 y F. they assume consider- able hardness, and crystallize in cubes, which are often as beautiful and large as those of bismuth. Ether and alcohol in- stantly destroy these amalgams, exciting 1 a brisk effervescence with them, and re- producing the pure mercurial globule. These amalgams are slightly permanent in the air, if undisturbed; but the least agi- tation is fatal to their existence. MM. Gay-Lussac and Thenard found, by im- mersion in water, that mercury, in passing to the state of a hydruret, absorbed 3^- times its volume of hydrogen. The am- moniacal hydruret of mercury and potas- sium may exist by itself; but as soon as we attempt to separate or oxidize the potassium, its other constituent principles also separate. Hence this hydruret is speedily decomposed by the air, by oxy- gen 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 rela- tive 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 clecompos- ea, especially by a slight agitation, and will give out hydrogen and ammonia in the ratio of l to 2."5. The mere ammoniacal hydrurets con- tain but a very small quantity of hydrogen and ammonia. By supposing 1 that in the AMM AMM ammoniacal hydniret of mercury, the hy- drogen is to the ammonia in the same pro- portion as in the ammoniacal hydruret of mercury and potassium, it will appear that the first is formed in volume, of 1 of mercury, 3.47 hydrogen, and 8.67 ammo- niacal gas, at the mean pressure and tem- perature of 30. and 60; or in weight, of about 1 800 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 atO, the freezing point of mercury ; but it is uncertain whether the appearances he observed may not have been owing to hy- grometric water, as happens with chlorine gas. The ammoniacal liquid loses its pun- gent smell as its temperature sinks, till at 50, it gelatinizes, if suddenly cooled ; but if slowly cooled, it crystallizes. Oxygen, by means of electricity, or a mere red heat, resolves ammoni t into wa- ter and nitrogen. When there is a consi- derable excess of oxygen, it acidifies a portion of the nitrogen into nitrous acid, whence many fallacies 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 mattrass, with a wide mouth and conical neck, over another with a taper neck, containing a mixture of sal ammo- niac and lime, heated by a lamp. As soon as the upper vessel seems to be full of am- monia, by the overflow of the pungent gas, it is to be cautiously lifted up, and in- serted, in a perpendicular direction, 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 invert- ing them, like a safidglass, the heavy chlo- rine and light ammonia, rushing in oppo- site directions, unite, with the evolution of flame. As one volume of ammonia con- tains, in a condensed state, one and a half of hydrogen, which requires for its satura- tion just one and a half of chlorine, 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 ammoniac and nitrogen are the results. The same thing happens on mixing the aqueous solutions of ammonia and chlo- rine. But if large bubbles of chlorine be letup into ammoniacal water of moderate strength, luminous streaks are seen in the dark to pervade the liquid, and the same reciprocal change of the ingredients is ef- fected. MM. Gay-Lussac and Thenard state that when 3 parts of ammoniacal gas, and I of chlorine, are mixed together, they cojdf- dense into sal ammoniac ; and azote, equal to 1-lOth the wi.ole volume, is given out. This result is at variance with their own theory of volumes. Three of ammoniacal gas consist of 4 hydrogen, and 1-J nitrogen in a condensed state ; 1 of chlorine seizes 1 of hydrogen, to form 2 of muriatic acid gas, which pre- cipitate with 2 of ammonia in a pulveru- lent 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 66 -^ on 0.33 of redundant ammonia, while 0.33 of a volume of nitrogen is left un- employed. Hence | of a volume, or of the original bulk of the mixed gases, ought to remain ; consisting of equal parts of ammonia and nitrogen, instead of l-10th of azote, as the French chemists state. Iodine has an analogous action on am- monia; seizing a portion ot its hydrogen to form hydriodic acid, whence hydriodate of ammonia results ; while another portion of iodine unites with the liberated nitro- gen, to form the explosive pulverulent iodide. Cyanogen and ammoniacal gas begin to act upon each other whenever they come into contact, but some hours are requisite to render the effect complete. They unite in the proportion nearly of 1 to 1, forming a compound which gives a dark orange-brown colour to water, but dis- solves in only a very small quantity in wa- ter. The solution does not produce prus-. sian blue with the salts of iron. By transmitting ammoniacal gas through charcoal ignited in a tube, prussic or hy- drocyanic acid is formed. The action of the alkaline metals on gaseous ammonia is very curious. When potassium is fused in that gas, a very fusi- ble olive green substance, consisting of potassium, nitrogen, and ammonia, is form- ed ; 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 po- tassium, 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 extreme thinness that it t appears semi-transparent ; and it has no- thing of the metallic appearance ; it heavier than water; and on minute in- spection seems imperfectly crystallized-. AMM When it is exposed to a heat progressive- ly increased, it melts, disengages ammo- nia, and hydrogen and nitrogen, in the proportions constituting ammonia; then it becomes solid, still preserving- 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 de- composition, with the extrication o^heat. Alkalis or alkaline salts are produced. Alcohol likewise decomposes it with sim- ilar results. The preceding description of the compound of ammonia with potas- sium, as prepared by MM. Gay-Lussac and Thenard, was controverted by Sir H. Davy. The experiments of this accurate che- mist led to the conclusion, that the pre- sence of moisture had modified their re- sults. In proportion as more precautions are taken to keep every thing absolutely dry, so in proportion, is less ammonia re- generated. He seldom obtained as much aa-rpof thq quantity absorbed; and he never could procure hydrogen and nitro- gen in the proportions constituting ammo- nia; there was always an excess of nitro- gen. The following experiment was conducted with the utmost nicety. 3 gr. of potassium were heated in 12 cubic inches of ammoniacal gas; 7.5 were ab- sorbed, and 3.2 of hydrogen evolved. On distilling 1 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 adopters. Of the 9 cubi- cal inches, one-fifth of a cubical inch only was ammonia; 10 measures of the perma- nent gas mixed with 7.5 of oxygen, and acted upon by the electrical spark, left a residuum of 7.5. He infers that the re- sults of the analysis of ammonia, by elec- tricity and potassium, are the same. On the whole, we may legitimately in- fer that there is something yet unexplain- ed in these phenomena. The potassium separates from ammonia, as much hydro- gen, as an equal weight of it would from water. If two volumes of hydrogen be thus detached from the alkaline gas, the remaining volume, with the volume of nitrogen, will be left to combine with the potassium, forming a triple compound, somewhat analagous to the cyanides, a compound capable of condensing ammo- nia. For an account of a singular com- bination of ammonia, by which its volatili- ty seems destroyed, see CULORIXE. When ammouiacal gas is transmitted over ignited wires of iron, copper, plati- AMM na, Sec. it is decomposed completely, ami though the metals are not increased in weight they have become extremely brittle. Iron, at the same temperature decomposes the ammonia, with double the rapidity that platinum does. At a high temperature, the protoxide of ni- trogen 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 tempera- ture the gas deoxidizes 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 fouth oxides of antimony, the oxide of tellurium, the protoxides of nickel, cobalt, and iron, the peroxides of tin, mercury, gold, and platinum. The first five are very soluble, the rest less so. These combinations can be obtained by evapo- ration, in the dry state, only wi*h copper, antimony, mercury, gold, platinum, and silver; the four last of which, are very re- markable for their detonating property. See the particular metals. All the acids are susceptible of combi- ning with ammonia, and they almost all form with it neutral compounds. M. Gay- Lussac made the important discovery, that whenever the acid is gaseous, its combination with ammoniacal gas, takes place in a simple ratio of determinate volumes, whether a neutral or a subsalt be formed. AMM ONI AC At SALTS have the following general characters. 1**, When treated with a caustic fixed alkali or earth, they exhale the peculiar smell of ammonia. 2d, They are generally soluble in wa- ter, and crystallizable. 3d, They are all decomposed at a mo- derate red heat; and if the acid be fixed, as the phosphoric or boracic, the ammo- nia comes away pure. 4th, When they are dropped into a so- hition of muriate of platina, a yellow pre- cipitate falls, 1. Jlcetate. This saline compound was formerly called the spirit of Mindererus, who introduced it into medicine as a fe- brifuge 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 sauccrful of sulphuric acid, and exhaust- ing the air, the salt will concrete in acicu- lar 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 AMM AMM of 212'. Or even muriate of ammonia will answer in the proportion of 27.9 to 100 of the acetate. Acetate of ammonia has a cooling- sweetish taste. It is deli- quescent, and volatile at all temperatures ; but it sublimes in the solid state at 250. It consists of 75| of dry acetic acid, and 242 ammonia. When intended for medi- cine, it should always be prepared from pure acetic acid, and subcarbonate of am- monia. .Arseniate of ammonia may be formed by saturating 1 the arsenic acid with ammonia, and evaporating 1 the liquid. Crystals of a rhomboidal prismatic form are obtained. Abinarseniate may also be made bv using an excess of acid. At a red heat, the am- monia 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, constitutes an extensive manufacture, we shall enter here into some additional details concern- ing- 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 col- lected. Globular g-lass vessels, about a foot in diameter, are filled within a few inches of their mouth with it, and are then ar- ranged in an oblong- furnace, where they are exposed to a heat gradually increased. The upper part of the glass balloon stands out of the furnace, and is kept relatively cool by the air. On the 3d day the oper- ation is completed, at which time they 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 grayish white colour, semi- transparent, and possessed of a degree of elasticity. 26 pounds of soot yield 6 of sal ammoniac. The ordinary mode of manufacturing sal ammoniac in Europe, is by combining with muriatic acid the am- monia resulting from the igneous decom- position of animal matters in close vessels. Cylinders of cast iron, fitted up as we have described under ACETIC Acin, 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 dis- tils over. Mr. Minish contrived a cheap method of converting this liquid into sal ammoniac. He digested it with pulve- ized gypsum, or simply made it percolate through a stratum of bruised gypsum; whence resulted a liquid sulphate of am- monia, and an insoluble carbonate of lime. The liquid, evaporated to dry ness, was mixed with muriate of soda, put into large glass balloons, and decomposed by a sub- liming heat. Sal ammoniac was found above in its characteristic cake, while sul- phate of soda remained below. M. Leblanc of St. Denis, near Paris, in- vented another method of much ingenui- ty, which is described by a commission of eminent French chemists in the 19th vo- lume of the Annalgs de Chimie, and in the Journal -d-e. Physique for the year 1794. He used tight brick kilns, instead of iron cylinders, for holding the materials to be decomposed. Into one he put a mixture of common salt and oil of vitriol ; into ano- ther, animal matters. Heat extricated from the first, muriatic acid gas, and from the second, ammgnia ; which bodies being conducted by their respective flues into a. third chamber lined with lead, and con- taining a stratum of water on its bottom, entered into combination, and precipitat- ed in solid sal ammoniac on the roof and sides, or 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 com- menced at Borrowstounness in Scotland, by Mr. Astley. He imbuetl in a stove- room, heated by brick flues, parings of skins, horns, and other animal matters, with the muriate of magnesia, or mother water of the sea-saltworks. The matters thus impregnated and dried, were sub- jected in a close kiln to a red heat, when the sal ammoniac vapour sublimed, and was condensed either in a solid form, into an adjoining chamber or chimney, or else into a stratum of water on its bottom. Mu- riate 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 after- wards be readily converted into the mu- riate, as above described. M. Leblanc used a kettle or eolipile for projecting steam into the leaden chamber to promote the combination. It is evident, that the exact neutralization, essential to sal am- moniac, might not be hit at first in these operations; but it could be afterwards ef- fected by the separate addition of a p6r- tion of alkaline or acid gas. As the mo- ther waters of the Cheshire salt-works contain only 3 per cent, of muriate of magnesia, they are not suitable, like thos* ANA ANA 6f sea-salt works, for the above manufac- ture.* * AiraoviAc (GUM). This is a gum-re- sin, which consists, according 1 to Bracon- not, 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 alkalis. Sp. gr. 1.200. It has a rather heavy smell, and a bitter sweet taste. It is in small aggluti- nated pieces of a yellowish white colour. It is used in medicine as an expectorant and antispasmodic.* AMMOXITES. These petrifactions, which have likewise been distinguishedby the name of cornua ammtmis, and are called snake-stones by the vulgar, consist chiefly of lime-stone. They are found of all si- zes, from the breadth of half an inch to more than two feet in diameter ; some of them rounded, other* greatly compress- ed, and lodged in different strata ol stones and clays. They appear to owe their ori- gin to shells of the nautilus kind. AMOMUM. Sfee PIMENTO. *. AMPHIBOLE. See IIonirBLEirnE and ACTYNOLITE.* * AMPHIGENE. See VESUVIA.* * AMYGDALOID.' A com iound mineral, consisting of spheroidal particles or vesi- cles of lithomarge, green earth, calc spar, steatite, imbedded in a basis of fine grain- ed green-s'one, or wacke, containing sometimes also crystals, of hornblende.* ANACARIHUM, Cashew Nut, or Marking 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 li- quor. ' This liquor forms a useful marking ink, as any thing written on linen or cot- ton with it, is of a brown colour, which gradually grows blacker, and is very du- rable. * A^ALCTME. Cubic Zeolite. This mi- neral is generally found in aggregated or cubic crystals, whose solid angles are replaced by three planes. External lus- tre between vitreous and pearly ; fracture, flat conchoidal; colours, white, gray, 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, 8 water, and 3 loss in 100 parts. It is found in granite, gneiss, trap Tocks and lavas, at Calton Hill Edinburgh, sit Taliskcr in Skye, in Dumbartonshire, in the Hartz, Bohemia, and at the Ferroe Islands. The variety found at Somma has been called sarcolite, from its flesh colour.* ANALYSIS. Chemical analysis consists of a great variety of operations, perform- ed for the purpose of separating the com- ponent parts of bodies. In these opera- tions the most extensive knowledge of such properties of bodies as are already discovered must be applied, in order to produce simplicity of effect, and certainty in the results. Chemical analysis can hardly be executed with success by one who is not in possession of a considerable number of simple substances in a state of great purity, many of 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 ex- hibited apart from each other ; or whether these distinctive properties be exhibited by causing them to enter into new com- binations, without the perceptible inter- vention of a separate state. The forming of new combinations is called synthesis; and in the chemical examination of bo- dies, 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, Bergmann, Berthollet, Kirwan, Vauquelin, and Ber- zelius. 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 processes, which are such as might be performed in the usual tem- perature of the atmosphere. Modern chemists have improved the process by fire, by a very extensive use of the blow- pipe (see BLOW-PIPK); and have succeed- ed in determining the component parts of minerals to great accuracy in the humid way. For the method of analyzing min- eral waters, see WATERS (MIXEHAL) ; and for the analysis of metallic ores, see OHES. Several authors have written on the ex- amination of earths and stones. The first step in the examination of con- sistent earths or stones is somewhat dif- ferent from that of such as are pulveru- lent. Their specific gravity should first be examined; also their hardness, whe- ther they will strike fire with steel, or can be scratched by the nail, or only by crys- tal, 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 whe- ther, they imbibe water, or whether \YMer ANA ANA an extract any thing from them by ebul- lition or digestion. od, Whether they be soluble in, or ef- fervesce with, acids, before or after pul- verization; or whether decomposable by boiling in a strong solution of potash. Sec. as gypsums and ponderous spars are. 4th, Whether they detonate with nitre. 5th, Whether they yield the fluor acid by distillation with sulphuric acid, or am- monia by distilling them with potash. 6th, Whether they be fusible per se with a blow-pipe, and how they are affected 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 calcareous 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 30tii volume of the Annales de Chimie, is the clearest which has yet been offered to the chemi- cal student. If the mineral be very hard, it is to be ignited in a covered crucible of platinum, and then plunged into cold water, to ren- der it brittle and easily pulverizable. The weight should be noted before and after this operation, in order to see if any vola- tile matter has been emitted. For the pur- pose of reducing stones to an impalpable powder, little mortars of highly hardened steel are now made, consisting of a cylin- drical 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 impalpable 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 ten primary earths, only four are usually met with in minerals, viz. silica, alumina, magnesia, and lime, associated with some metallic oxides, which are com- monly iron, manganese, nickel, copper and chromium. If neither acid nor alkali be expected to be present, the mineral is mixed in a sil- ver crucible, with thrice its weight of pure potash and a 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 inspection, be a 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 pour- ed on, and a gentle heat applied, if neces- sary, to accomplish its solution. If the li- quid 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 dryness, 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 evaporation, it assumes a gelatinous con- sistence. At this period it must be stirred frequently with a platinum spatula or glass rod, to promote the disengagement of the muriatic acid gas. After this, the heat may be raised to fully 212 V. for a few minutes. Hot water is to be now poured on in considerable abundance, which dis- solves every thing 1 except the silica. By filtration, this earth is separated from the liquid; and being edulcorated with hot water, it is then dried, ignited, and weigh- ed. It constitutes a fine white powder, in- soluble in acids, and feeling gritty be- tween the teeth. If it be coloured, a lit- tle 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. Carbonate of potash being then added, till it indicates alkaline excess, the liquid must be made to boil for a little, A copious precipitation of the earth and oxides is thus produced. The whole is thrown on a filter, and after it is so drained as to as- sume a semi-solid consistence, it is re- moved by a platinum blade, and boiled in a capsule for some time, with solution of pure potash. Alumina and glucina 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 continues dissolved. The first earth separated by filtration, washed, dried, and ignited, gives the perfect glass, silica may be regarded as quantity of alumina. The nature of this the chief constituent of the stone ; but if may be further demonstrated, by treating the vitrification be very imperfect and the it with dilute sulphuric acid, and sulphate bulk much increased, alumina may be of potash, both in equivalent quantities, supposed to predominate. A brownish or when the whole wftl be converted into ANA ANA akim. (See ALUM). The filtered liquid will deposite its glucina, on dissipating- the ammonia, by ebullition. It is to be sepa- rated by nitration, to be washed, ignited, and weighed. The matter undissolved by the diges- tion of the liquid potash, may consist of lime, magnesia, and metallic oxides. Di- lute sulphuric acid must be digested on it for some time. The solution is to be evap- orated to dryness, and heated to expel the excess of acid. The saline solid mat- ter being now diffused in a moderate quantity of water, the sulphate of magne- sia 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 magnesianand metal- lic 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. Hydrosulphu- ret of potash will throw down the manga- nese, from the magnesian solution. The addition of pure potash, aided by gentle ebullition, wiH then precipitate the mag- nesia. The oxide of manganese may be freed from the sulphuretted hydrogen, by ustulation. The mingled metallic oxides must be digested with abundance of nitric acid, to acidify the chromium. The liquid is next . treated with potash, which forms a soluble ehromate, while it throws down the iron and nickel. The chromic acid may be se- parated from the potash by muriatic acid, and digestion with heat, washed, dried till it becomes 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 sublime and leave the oxide of nickel be- hind. The whole separate weights must now be collected 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 ac- count of the composition of the mineral. But if the deficiency be considerable, then ome 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 por- celain retort, to which a refrigerated re- ceiver is fitted. The water or other vola- tile and condensable matter, if any be pre- sent, will thus be obtained. 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 ex- pelled by digestion with sulphuric acid. It is exactly characterized by its property of corroding glass.* Beside this general method, some oth- ers may be used in particular cases. Thus, to discover a small portion of alu- mina or magnesia in a solution of a large quantity of lime, pure ammonia may be applied, which will precipitate the alumi- na or magnesia (if any be), but not the lime. Distilled vinegar applied to the pre- cipitate will discover whether it be alu- mina or magnesia. 2c//?/, A minute portion of lime orbary- tes, in a solution of alumina or magnesia, may be discovered by the sulphuric acid, which precipitates the lime and barytes : the solution should be dilute, else the alu- mina 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 limef 100 grains of sulphate of barytes contain 66 of barytes; 100 grains of oxalate of lime con- tain 43.8 of lime. The insolubility of sul- phate of barytes in 500 times its weight of boiling water, sufficiently distinguishes it. From these data the quantities are easily investigated. 3dly t A minute proportion of alumina in a large quantity of magnesia may be dis- covered, either by precipitating the whole, and treating it with distilled vinegar; or by heating the solution nearly to ebulli- tion, and adding more carbonate of mag- nesia, until the solution is perfectly neu- tral, which it never is when alumina is con- tained in it, as this requires an excess 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 exactness, it may be decomposed by boiling it in volatile alkali). After the precipitation, the solution should be large- ly diluted, as the sulphate of magnesia, which remained in solution while hot, would precipitate when cold, and mix with the embryon alum. Aithty, A minute portion of magnesia in a large quantity of alumina is best separat- ed by precipitating the whole, and treat- ing the precipitate with distilled vinegar. Lastly, Lime and barytes are separated by precipitating both with the sulphuric acid, and evaporating the solution to a small compass, pouring off the liquor, and treating the dried precipitate with 500 times its weight of boiling water; what remains undissolved is sulphate of bary- tes. The inconveniences of employing much heat, are obvieus, and Mr. Lowitz informs ANA ANA 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 fur- nace four inches high and three in diame- ter, with air-holes, and a cover perforated to hold the crucible, he boils the stone prepared as directed above, stirring it fre- quently. His crucible, which, as well as the spatula, is of very line 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 refractoriness ofthe fos- sil require it. Large tough bubbles ari- sing during the boiling, are in general a sign that the process will be attended 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 the 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 dissolved 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 evaporate the solution till it is re- duced to an ounce and half, or two ounces. If the stone contained silex, it will sepa- rate in this process, and must be collect- ed on a filter, and edulcorated with dis- tilled 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 ammonia, and boiled with an excess of this salt, till all that will precipitate has fallen down. The earths and metallic oxides being separated 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 ex- pose it to a heat of 450 F. when the ni- trate of ammonia will be decomposed, and the nitrate of potash or soda will re- main in the vessel. The earths and me- tallic oxides, that remained on the filter, may be distinguished by the common pro- cesses. The alumina may be separated by solution of potash, the lime by sulphu- ric acid, the oxide of iron by succinate of ammonia, the manganese by hydrosul- phuret of potash, and the magnesia by pure soda. * Lately carbonate or nitrate of barytes has been introduced into mineral analysis with great advantage, for the fluxing 1 of stones, that may contain alkaline mutter. See the English Translation of M. The- nard's volume on analysis.* Under the head of mineral analysis, no- thing is of so much general importance as the examination of soils, with a view to the improvement of such as are less pro- ductive, by supplying 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 observations of Mr. Young, and his own skill in chemis- try, having given at large, in a manner best adapted for the use of the practical farmer, an account of the methods to be pursued for this purpose, we shall here copy them. The substances found in soils are cer- tain mixtures or combinations of some of the primitive earths, animal and vegetable matter in a decomposing state, certain sa- line compounds, and the oxide of iron. These bodies always retain water, and ex- ist in very different proportions in differ- ent lands, and the end of analytical ex- periments is the detection of their quanti- ties 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 characters of which see the articles. Si- lex composes 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 particles of these soils, it is ge- nerally united with silex and oxide of iron. Lime always exists in soils in a state of com- bination, 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 gyp- sum ; with phosphoric acid, phosphate of lime, or the earth of bones. Carbonate of lime, mixed with other substances, com- poses chalky soils and marls, and is found in soft sandy soils. Magnesia is rarely found in soils : when it is; it is combined with carbonic acid, or with silex and alu- mina. Animal decomposing matter exists in different states, contains much carbo- naceous substance, volatile alkali, inflam- mable aeriform products, and carbonic acid. It is found chiefly in lands lately- manured. Vegetable decomposing mat- ter usually contains still more carbonace- ANA ANA ous substance, and differs from the pre- ceding principally in not producing vola- tile 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 are chiefly muriate of soda, or common salt, sulphate of magnesia, muriate and sulphate of pot- ash, nitrate of lime, and the mild alkalis. Oxide of iron, which is the same with the rust produced by exposing iron to air and water, is found in all soils, but most abun- dantly in red and yellow clays, and red and yellow siliceous sands. The instruments requisite for the analy- sis of soils are few. A pair of scales capa ble 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 iroy to a grain : a wire sieve, coarse enough to let pepper- corn pass through : an Argand lamp and stand : a few glass bottles, Hessian cruci- bles, and china or queen's ware evapora- ting basins : a Wedgwood pestle and mor- tar : 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 collect- ing 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 carbo- nate of ammonia, muriate of ammonia, neutral carbonate of potash, 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 pro- perties. It sometimes 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. 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 calcareous, and another pai't silice- ous; and in this and analogous cases, the portions different from each other should be analyzed separately. Soils when col- lected, if they cannot be examined imme- diately, should be preserved in phials quite filled with them, and closed with ground glass stopples. The most conve- nient 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 in- troducing into a phial, which will contain a known quantity of water, equal bulks of A\ ater and of the soil ; which may easi- ly be done, by pouring in water till the phial is half full, and then adding the soii till the fluid rises to the mouth. The dif- ference between the weight of the water, and that of the soil, will give the result. Then if the bottle will contain four hun- dred 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 gravi- ty of a soil should be known, as it affords an indication of the quantity of animal and vegetable maiter it contains ; these sub- stances being alw ays most abundant in the lighter soils. The o.her physical proper- ties of soils should likewise be examined before the analysis is made, as they de- note, to a certain exient, their composi- tion, and serve as guides in directing the experiment . Thus siliceous soils are generally rough to the touch, and scratch glass when rubbed upon it : aluminous 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. boils, when as dry as they can be made by exposure to the air, still retain a considerable quantity of water, which ad- heres 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'affecting their composi- tion in other respects, lliis 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 oOO F. ; and if a thermometer be not used, the pro- per degree of heat may easily be ascer- tained by keeping a piece of wood in the basin in contact with its bottom ; for as long as the colour of the wood remains un- altered, the heat is not too high; but as soon as it begins to be charred, the pro- cess must be stopped. In several expe- riments, in which Sir H. Davy collected the water that came over at this degree of heat, he found it pure, without any sensi- ble 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 degree absorbent and retentive of water, and will generally be found to contain a large proportion of aluminous earth . if the loss be not more than 10 or 20 grains, the land may be considered as slightly ab- sorbent and retentive, and the siliceous earth as most abundant. 3. None of the loose stones, gravel, or ANA ANA large vegetable fibres, should be separa- ted from the soil, till the water is thus ex- pelled ; for these bodies are often highly absorbent and retentive, and consequent- ly 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, easi- ly scratched with a knife, and incapable of effervescing with acids. 4. Most soils, beside 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 di- vided, such as clay, loam, marl, and vege- table and animal matter. This may be done sufficiently by mixing the soil well with water ; as the coarse sand will gene- rally 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 con- taining 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 separated is seldom or never necessary, and its nature may be detected in the same way as that of the stones anil gravel. It is always siliceous sand, or calcareous sand, or both together. If it consist wholly of carbonate of lime, it will dis- solve rapidly in muriatic acid with effer- vescence ; 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 sili- ceous part; which being washed, dried, and heated strongly in a crucible, the difference of its weight from that of the whole, will indicate the quantity of the calcareous sand. 6. The finely divided matter of the soil is usually very compound in its na- ture ; it sometimes contains all the four primitive earths of soils, as well as animal and vegetable matter; and to ascertain the proportions of these with tolerable Vot. r. [22] accuracy, is the most difficult part of the subject. The first process to be perform- ed in this part of the analysis is the expo- sure of the fine matter of the soil to the action of muriatic acid. This acid, dilu- ted with double its bulk of water, should be poured upon the earthy matter in an evaporating basin, in a quantity equal to twice the weight of the earthy matter. The mixture should be often siirred, 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 dis- tilled or rain water, dried at a moderate heat, and weighed. Its loss will denote the quantity of solid matter taken up. The washings must be added to the solu- tion ; 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 solu- tion of the prussiate must be dropped in, till no further effect is produced. To as- certain its 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 carbonate of potash must be poured till all effervescence 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 after- ward weighed. The remaining fluid must be boiled for a quarter of an hour, when the magnesia, if there be any, will be pre- cipitated 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 alu- mina should, from peculiar circumstances, 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 sufficient to cover the solid matter: for this lye dissolves alumina, without acting upon carbonate of lime. Should the fine- ly divided soil be sufficiently calcareous to effervesce very strongly with acids, a sim- ple method of ascertaining the quantity of carbonate of lime, sufficiently 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 45 parts in a hundred by weighty ANA ANA the quantity of this acid given out during the effervescence occasioned by its solu- tion 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 Avater, and mix the acid slowly in small portions with the soil, till it ceases to oc- casion any effervescence, by weighing 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 Ofcllect the carbonic acid in the pneumatic appa- ratus for ih? analysis of soils, described in the article LAHOHATORY; and allow for every ounce measure of the carbonic acid, t\vo grains of carbonate of lime. 7. The quantity of insoluble animal and vegetable matter may next be ascertained with sufficient precision, by heating 1 it to a strong red heat in a crucible over a com- mon fire, till no blackness remains in the mass, stirring it frequently meanwhile with a metallic wire. The loss of weight \vill 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 de- notes a considerable proportion of vege- table 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 decomposi- tion 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 water, allowing a hun- dred 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 sepa- rated, washed, dried, and weighed, in the usual manner. Carbonate of ammonia be- ing added to the solution in quantity more than sufficient to saturate the acid, the alumina will be precipitated; and the ox- ide 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 maybe separated as directed a'bove for the muri- atic. This method of analysis is sufficient- ly precise for all common purposes : but if very great accuracy be an object, the residuum 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 sepa- rating the sand. This water must be evaporated to dry ness 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 mu- cilaginous, or gelatinous matter. If it be white and transparent, it may be consid- ered as principally saline. Nitrate of pot- ash or of lime is indicated in this saline matter by its sparkling when thrown on burning coals: sulphate of magnesia may be detected by its bitter taste : and sul- phate of potash produces no alteration in a solution of carbonate of ammonia, but precipitates a solution of muriate of ba- rytes. 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 powdered charcoal, and kept at a red heat in a crucible for half an hour. The mixture must then be boil- ed a quarter of an hour in half a pint of water, and the solution, being filtered, exposed some days to the open air. ]f any soluble quantity of sulphate of lime, or gypsum, 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 solu- ble earths. The solution must be eva- porated, and water poured upon the solid matter. This fluid will dissolve the com- pounds of earths with the muriatic acid, and leave the phosphate of lime un- touched. 11. When the examination of a soil is completed, 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 phosphate or sulphate of lime is discovered by the independent process, No. 10, just mentioned, a correction must be made for the general process, by sub- tracting a sum equal to their weight from the quantity of carbonate of lime obtain- ANA ANA Phosphate of lime, Amount of all the products, Loss, ed 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 may be sup- posed to contain, grains. Of water of absorption, - - 18 Of loose stones and gravel principal- ly siliceous, ... - 42 Of undecompounded vegetable fi- bres, 10 Of fine siliceous sand, - - 200 Of minutely divided matter, separa- ted by" filtration, and consisting of, Carbonate of lime, - 25 Carbonate of magnesia, - 4 Matter destructible by heat, principally vegetable, - 10 Silex, .... 40 Alumina, ... 32 Oxide of iron, 4 Soluble matter, principally sul- phate of potash and vegeta- ble extract, . 3 2 125 395 5 400 Tn this instance the loss is supposed small ; but in general, in actual experi- ments, it will be found much greater, in consequence of the difficulty of collecting the whole quantities of the different pre- cipitates; and when it is within thirty for four hundred grains, there is no reason to suspect any want of due precision in the processes. 12. When the experimenter is become acquainted with the use of the different instruments, the properties of the re- agents, and the relations between the ex- ternal and chemical qualities of soils, he will seldom find it necessary to perform, in any one case, all the processes that have been described. When his soil, for instance, contains no notable proportion 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 experiment with sulphuric acid, No. 8. In the fn-st trials that are made by per- sons unacquainted with chemistry, they must not expect much precision of result. Many difficulties will be met with ; but in overcoming them the most useful kind of practical knowledge will be obtained ; and nothing is so instructive in experimen- tal science as the detection of mistakes. The correct analyst ought to be well grounded in general chemical informa- tion ; but perhaps there is no better mode of gaining it than that of attempting origi- nal investigations. In pursuing his ex- periments, he will be continually obliged to learn from books the history of the sub- stances he is employing or acting upon ; and his theoretical ideas will be more va- luable in being connected with practical operation, and acquired for the purpose of discovery. The analysis of vegetables requires vari- ous 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 per- fection. Some of the immediate materials of vegetables are separated to our hands by Nature in a state of greater or less purity ; as the gums, resins, and balsams, that ex- ude from plants. The expressed juices contain various matters, that may be sepa- rated by the appropriate reagents. Mace- ration, infusion, and decoction in water, take up certain part* soluble in this men- struum ; and alcohol will extract others that water will not dissolve. The mode of separating and distinguishing these ma- terials will easily be collected from their characters, as given under the head VEGE- TABLE KINGDOM, and under the different articles themselves. * As the ultimate constituents of all ve- getable substances are carbon, hydrogen, and oxygen, with occasionally azote, the problem of their final analysis resolves into a method of ascertaining the proportion of these elementary bodies. MM. Gay-Lus- sac and Thenard contrived a very elegant apparatus for vegetable and animal analy- sis, in which the matter in a dried state was mixed with chlorate of potash, and formed into minute pellets. These pel- lets being projected through the interven- tion of a stop-cock of peculiar structure into an ignited glass tube, were instantly resolved into carbonic acid and water. The former product was received over mercury, and estimated by its condensa- tion with potash ; the latter was intercep- ted 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 oxy- gen, derived from the organic substance, as well as the residual azote, of the gase- ous products. M. Berzelius modified the above appa- ratus, and employed the organic product ANA ANH jin combination with a base, generally ox- ide of lead. He mixed a certain weight of this neutral compound with a known quantity of pure chlorate of potash, and triturated the whole with a large quantity of muriate of soda, for the purpose of mo- derating the subsequent combustion, This mingled dry powder is put into a glasstube 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 hermeti- cally sealed beforehand, the other is now drawn to a pretty fine point by the blow- pipe. This termination is inserd into a glass globe about an inch diameter, which joins it to a long tube containing dry muriate of lime in its middle, and dip- ping at its other extremity into the mer- cury of a pneumatic trough. The first tube, with its protecting tin case, being exposed gradually to ignition, the enclo- sed materials are resolved into carbonic acid, water, and azote, which come over, and are estimated as above described. M. Gay-Lussac has more recently employed peroxide of copper to mix with the or- ganic 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 forma- tion of nitric acid with the chlorate of pot- ash 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 comple- ting analyses of organic substances with the heat of a lamp. Hydrogen having the power in minute quantities of modifying the constitution of the organic bodies, re- quires to be estimated with corresponding minuteness. Mr. Porrett has very inge- niously suggested, that its quantity may be more accurately determined by the proportion of oxide of copper that is re- vived, than by the product of water, Di- lute 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 expen- ded in its reduction. One of hydrogen corresponds to 9 of water, and 32 of cop- per. Under the different vegetable and ani- mal products, we shall take care to state their ultimate constituents by the most correct and recent analyses. The pecu- liar substances which M ater, alcohol, ether, and other solvents, can separate from an organic body may be called the immedi- ate products of the vegetable or animal kingdom; while the carbon, hydrogen, oxygen, and azote, discoverable by igne- ous analysis, are the ultimate constituent elements. To the former class belong sugar, gum, starch, oils, resins, gelatin, urea, organic acids and alkalis, &c. which see.* * AXATASE. Octohedrite, oxide of tita- nium, rutile, and titane rutile. This mi- neral shows a variety of colours by re- flected light, from indigo-blue to reddish- brown. By transmitted light, it appears greenish-yellow. It is found usually in small crystals, octohedrons, with isosceles triangular faces. Structure lamellar; it is semi-transparent, 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 mi- neral. It occurs in granite, gneiss, mica slate, and transition limestone.* * AIH>ALU&ITE, A massive mineral, of a flesh and sometimes rose-red colour. It is, however, occasionally crystallized in rectangular four-sided prisms, verging on rhomboids, The structure of the prising is lamellar, with joints parallel to their sides. Translucent ; scratches quartz ; is easily broken; sp. gr. 3.165. Infusible by the blow-pipe ; in which respect it dif- fers from feldspar, though called fdspath apyre by Haiiy. It is composed of 52 alu- mina, 32 silica, 8 potash, 2 oxide of iron, and 6 loss, Vauq. It belongs to primi- tive countries, and was first found in An- dalusia in Spain. It is found in mica slate in Aberdeenshire, and in the Isle of Unst ; Dartmoor in Devonshire ; in mica slate at Killiney, near Dublin, and at Douce Moun- tain, county Wicklow.* * ANDHEOLITE. See HARMOTOME.* * ANHYDRITE. Anhydrous gypsum. There are six varieties of it. 1. Compact, has various shades, of white, blue, and red ; massive and kidney -sha- ped; 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 mas- sive concretions, of which the structure is confusedly foliated. White or bluish co- lour, of a pearly lustre ; composition as above, with pne per cent, of sea salt. It occurs in the salt mines of Halle ; sp. gr. 2.957. 3. Fibrous. Massive ; glimmer- ing, pearly lustre ; fracture in delicate parallel fibres ; scarcely translucent ; easi- ly broken. Found at Halle, Ischel, and near Brunswick. 4. Radiated. Blue, some- times spotted with red ; radiated, splen- dent fracture ; partly splintery ; translu- ANI ANI cent; not hard; sp. gr. 2.940. 5. Spar- ry, or cube spar. Milk-white colour, pas- sing sometimes into grayish 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 re- sults an eight-sided prism ; lustre, splen- dent, pearly. Foliated fracture. Three- fold rectangular cleavage. Cubical frag- ments. Translucent. Scratches calc spar. Brittle. Sp. gr. 2 9. This is the muria- ite of some writers, it is doubly re- fracting. It is said to contain one per cent, of sea salt, it is found at Bex in Switzer- land, and Halle in the Tyrol. 6. Silicife- pous, or vulpinite. Massive concretions of a laminated structure, translucent on the edges, splendent, and brittle. Gray- ish-white, veined with bluish-gray. Sp. gr. 2.88. It contains eight per cent, silex. The rest is sulphate of lime. It is called by statuaries, Marino bardiglio di Berga- mo, and takes a fine polish. It derives its name from Vulpino in Italy, where it accompanies lime.* ANIL, or NIL This plant, from the leaves of which indigo is prepared, grows in America. ANIMAL KINGDOM. The various bodies around us, which form the objects of che- mical research, have all undergone a num- ber of combinations and decompositions before we take them in hand for exami- nation. These are all consequences of the same attractions or specific proper- ties that we avail ourselves of; and are modified likewise by virtue of the situa- tions and temperatures of the bodies pre- sented to each other. In the great mass of unorganized matter, the combinations appear to be much more simple than such as take place in the vessels of organized beings, namely, plants and animals : in the former of which there is not any pecu- liar structure of tubes conveying various fluids; and in the latter there is not only an elaborate system of vessels, but like- Avise, for the most part, an augmentation of temperature. From such causes as these it is, that some of the substances afforded by animal bodies are never found either in vegetables or minerals; and so likewise in vegetables are found certain products never unequivocally met with among minerals. Hence, among the sys- tematical arrangements used by chemists, the most general is that which divides bodies into three kingdoms, the animal, the vegetable, and the mineral. Animal, as well as vegetable bodies, may be considered as peculiar apparatus for carrying on a determinate series of chemical operations. Vegetables seem capable of operating with fluids only, and at the temperature of the atmosphere, as we have just noticed. But most animals have a provision for mechanically divi- ding solids by mastication, which answers the same purpose as grinding, pounding, or levigation, does in our experiments; that is to say, it enlarges the quantity of surface to be acted upon by solvents. The process carried on in the stomach ap- pears to be of the same kind as that which we distinguish 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 use- less. 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 chemical action of its parts is capable of producing, but is likewise ex- posed to the air of the atmosphere in the lungs, into which that elastic fluid is ad- mitted 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 con- densed, and combines with the blood, at the same time that it gives out a large quantity of heat, in consequence of its own capacity for heat being diminished. A small portion of azote likewise is ab- sorbed, and carbonic acid is given out. Some curious experiments of Spallanza- ni show, that the lungs are not the sole organs by which these changes are ef- fected. 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 atmos- pheric air of its oxygen as completely as phosphorus. Shells, however, lose this property when their organization is de- stroyed by age. Amphibia, deprived of their lungs, lived much longer in the opea air, than others in air destitute of oxygen. It is remarkable, that a larva, weighing a few grains, would consume almost asmuck oxygen in a given time as one of the am- phibia a thousand times its bulk. Fishes, alive and dead, animals, and parts of ani- mals, confined under water in jars, ab- sorbed 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 pur- ANI ANI pose, if we were to attempt an explana- tion of the little we know respecting 1 the manner in which the secretions or combi- nations 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 products of the mineral kingdom. We shall therefore only add, that these or- ganized being's are so contrived, that their existence continues, and all their func- tions are performed, as long 1 as the ves- sels are supplied with food or materials to occupy the place of such as are cSrried 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 inter- rupted in any very considerable degree, the chemical arrangements become alter- ed; the temperature in land animals is changed ; the minute vessels are acted upon and destroyed ; life ceases, and the admirable structure, being no longer suf- ficiently perfect, loses its figure, and re- turns, by new combinations and decom- positions, to the general mass of unorgani- zed matter, with a rapidity which is usual- ly greater, the more elaborate its construc- tion. -j- Within the sphere of vitality, peculiar laws of decomposition and recomposition seem to prevail, in like manner as within the sphere of the voltaic circuit. Indeed each gland seems to have a capacity to induce peculiar corpuscular reactions, giving rise to its appropriate secretions. In the living stomach, food passes to the state of chyme ; when in the absence of life, the same matter, at the same tempera- ture, would putrefy .f The parts of vegetable or animal sub- Stances may be obtained, for chemical examination, either by simple pres- sure, 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 destruc- tive 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 decom- position or fermentation, wherein the component parts take a new arrangement, and form compounds which did not for the most part exist in the organized sub- stance; or, lastly, the judicious chemist will avail himself of all these several methods singly, or in combination. He will, according to circumstances, separate the parts of an animal or vegetable sub- stance by pressure, assisted by heat; or by digestion or boiling- in various fluids, added in the retort which contains the substance under examination. He will attend particularly to the products which pass over, whether they be permanently elastic, or subject to condensation in the temperatures we are able to produce. In some cases, he will suffer the spontaneous decomposition to precede the application of chemical methods ; and in others, he will attentively mark the changes which the products of his operations undergo in the course of time, whether in closed ves- sels, or exposed to the open air. Thus it is, that, in surveying the ample field of nature, the philosophical chemist posses- ses numerous means of making discove- ries, if applied with judgment and sagaci- ty ; though the progress of discovery, so far from bringing us nearer the end of our pursuit, appears continually to open new scenes; and, by enlarging our powers of investigation, never fails to point out ad- ditional objects of enquiry. Animal and vegetable substances ap- proach each other by insensible grada- tions ; 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 ani- mal substances is that of affording volatile alkali by destructive distillation. Some plants, however, afford it likewise. Nei- ther contain it ready formed ; but it ap- pears to be produced by the combination of hydrogen and azote, during the changes produced either by fire, or the putrefac- tive process. See AIIMIONIA. Our knowledge of the products of the animal kingdom, by the help of chemical analysis, is not yet sufficiently matured to enable us to arrange them according to the nature of their component parts, which appear to consist chiefly of hydro- gen, oxygen, carbon, and azote ; and with these, sulphur, phosphorus, lime, magne- sia, and soda, are frequently combined in variable proportions. * The following are the peculiar chem- ical products of animal organization. Ge- latin, albumen, fibrin, caseous matter, co- louring matter of blood, mucus, urea, pi- cromel, osmazome, sugar of milk, and sugar of diabetes. The compound animal products are the various solids and fluids, whether healthy or morbid, that are found in the animal body; such as muscle, skin, bone, blood, urine, bile, morbid concre- tions, brain, &c.* When animal substances are left expo- sed to the air, or immersed in water or other fluids, they suffer a spontaneous change, which is more or less rapid ac- cording to circumstances. The sponta- neous change of organized bodies is dis- tinguished by the name of fermentation. In vegetable bodies there are distinct sla- ANN ANN ges or periods of this process, which have been divided into the vinous, acetous, and putrefactive fermentations. Animal sub- stances are susceptible only of the two latter, during which, as in all other spon- taneous changes, the combinations of chemical principles become in general more and more simple. There is no doubt but much instruction might be obtained from accurate observations of the putre- factive processes in all their several va- rieties and situations ; but the loathsome- ness and danger attending on such enqui- ries have hitherto greatly retarded our progress in this department of chemical science. See FERMENTATION (PUTREFAC- TIVE). ANITCE, improperly called gum anime, is ft resinous substance imported from New Spain and the Brazils. There are two kinds, distinguished by the names of ori- ental and occidental. The former is dry, and of an uncertain colour, some speci- mens 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 burn- ing 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 con- siderable degree of the taste and flavour of the anime ; the distilled water discovers on its surface some small portion of essen- tial oil. This resin is used by perfumers, and also in certain plasters, wherein it has been supposed 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 consid- erable number of instances of bodies which are capable of undergoing ignition, it is found that sudden cooling renders them hard and brittle. This is a real in- convenience in glass, and also in steel, when this metallic substance is required to be soft and flexible. The inconve- niences are avoided by cooling them very gradually, and this process is called an- nealing. 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 1 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. f Malleability, ductility and toughness, in substances susceptible of the annealing process, are probably dependent on the quantity of caloric remaining in combina- tion with their particles, while in the solid state. When malleable metals are ham- mered, they give out heat and become harder, more rigid and more dense, until a certain maximum is attained. After- wards they neither heat nor harden, and crush to pieces, if the process be not suspended. Exposed to the fire until softened., on cooling they are found to have regained the properties of which percussion had deprived them ; and they may be again hammered, heated, harden- ed, and condensed. The sudden abstrac- tion of caloric from the exterior strata of particles in a piece of thick glass, is not attended by a corresponding abstraction of this principle from among the particles within, owing to the slowness, with which glass conducts heat. Hence cohesion is not general ; and the particles are not ar- ranged uniformly, unless the cooling be very slow, so as to allow the refrigera- tion, within and without, to be nearly si- multaneous. As it never can be perfectly simultaneous in thick glass, it is never perfectly well annealed. The process would be more perfect, were the articles subjected to radiant heat only ; as this, when projected from red-hot surfaces, penetrates through glass, as I have ascer- tained. By gradually making up fires of charcoal at about 4 inches distance on each side of a glass tube of about an inch and a quarter in thickness, and with a very small bore, I was enabled to heat and bend it. From its situation, it was only subjected to radiant heat.j- ANNOTTO. The pellicles of the seeds of the bixa orellana, a liliaceous shrub, from 15 to 20 feet high in good ground, affbrr| the red masses brought into Eu- rope, under the name of Annotto, Orlean, and Koucou. The annotto commonly met with among us is moderately hard, of a brown colour on the outside, and a dull red within. It is difficultly acted upon by water, and tin- ges the liquor only of a pale brownish yellow colour. In rectified spirit of wine it very readily dissolves, and communi- cates a high orange or yellowish-red. Hence it is used as an ingredient in var- nishes, for giving more or less of an orange cast to the simple yellows. Alka- line salt renders it perfectly soluble in boiling water, without altering its colour. Besides its use in dyeing, it is employed for colouring- cheese. ANT ANT * AirrflopHTLLiTE. A massive mineral fa brownish colour ; sometimes also crys- tallized, in thin flat six-sided prisms, streaked lengthwise. It has a false metal- lic lustre, glistening 1 and pearly. In crys- tals, transparent. Massive, only translu- cent on the edges. It does not scratch glass, but fluate of lime. Specific grav- ity 3.2. Somewhat hard but exceeding- ly brittle. Infusible alone before the blow-pipe, but with borax it gives a grass- green transparent bead. It consists of 56 silica, 13.3 alumina, 14 magnesia, 3.33 lime, 6 oxide of iron, 3 oxide of manganese, 1.43 water, and 2.94 loss in 100. It isffound Konigsberg in Norway.* * AN f HUACITE. Blind coal, Kilkenny eoal, or glance-coal. There are three va- rieties. 1. Massive, the conchoidal of Ja- meson. Its colour is iron-black, some- times tarnished on the surface, with a splendent metallic lustre. Fracture con- ehoidal, with a pseudo-metallic lustre. It is brittle and light. It yields no flame, and leaves whitish ashes. It is found in the newest floetz formations, at Meissner in Hesse, aod Walsall in Staffordshire. 2. Slatv anthracite. Colour black, or bro wn- jsh -black. Imperfect slaty in one direc- tion, with a slight metallic lustre. Brittle. Specific gravity 1.4 to 1.8. Consumes without flame. It is composed of 72 car- bon, 13 silica, 3.3 alumina, and 3. 5 oxide of iron. It is found in both primitive and se- condary rocks ; at Calton Hill, Edinburgh ; near Walsall Staffordshire ; in the south- ern parts of Brecknockshire, Carmarthen- shire, and Pembrokeshire, whence it is called Welsh culm ; near Cumnock, and Kilmarnock, Ayrshire ; and most abun- dantly at Kilkenny, Ireland. 3. Colum- nar anthracite. In small short prisma- tic concretions, of an iron-black colour with a tarnished metalliclustre. It isbrittle, soft, and light. It yields no flame or smoke. It forms a thick bed near Sanquhar, in Dumfries-shire ; at Saltcoats and New Cumnock, in Ayrshire. It occurs also at Meissner in Hesse.* , p AWTIMOXV. The word antimo is al- ways used in commerce to denote a metal- lic ore, consisting of sulphur combined with the metal, which is properly called antimony. Sometimes this sulphuret is termed crude antimony, to distinguish it from the pure metal, or regulus, as it was formerly called. According to Professor Proust, the sulphuret contains 26 per cent of sulphur. lie heated 100 parts of anti- mony with an equal weight of sulphur in a glass retort, till the whole was well fu- sed and the excess of sulphur expelled, and the sulphuret remaining was 135. The result was the same after repeated trials : 100 parts of antimony, with 300 of red sulphuret of mercury, afforded 135 to 1S6 of sulphuret. These artificial sulpim- rets lost nothing by being kept in fusion an hour ; and heated with an equal weight of sulphur, they could not be made to take up more. Some of the native sulphu- rets of the shops, however, appear to have a small portion more of sulphur uni- ted with them, as they will take up an ad- dition of 7 or 8 per cent of antimony. Antimony is of a dusky white colour, very brittle, and of a plated or scaly tex- ture. Its specific gravity, according to Brisson, is 6.7021, but Bergmann makes it 6.86. Soon after ignition it melts, and by a continuance of the heat it becomes oxidized, and rises in white fumes, which may afterwards be volatilized a second time, or fused into a hyacinthine glass, ac- cording to the management of the heat: the first were formerly called argentine flowers of regulus of antimony. In closed vessels the antimony rises totally without decomposition. This metallic substance is not subject to rust by exposure to air, though its surface becomes tarnished by that means Its oxides are a little soluble in water; and in this respect they resem- ble the oxide of arsenic, by an approach toward the acid state. * There are certainly three, probably four, distinct combinations of antimony and oxygen: 1. The protoxide of Berze- lius is a blackish-gray powder, obtained from a mixture of powder of antimony and water, at the positive pole of a voltaic cir- cuit. Heat enables this oxide to absorb oxygen rapidly, converting it into the tri- toxide. According to Berzelius, it con- sists of 100 of metal, and 4.65 oxygen. It must be confessed, however, that the data for fixing these proportions are very doubtful. 2. The deutoxide may be ob- tained by digesting the metal in powder in muriatic acid, and pouring the solution into water of potash. Wash and dry the precipitate. It is a powder of a dirty white colour, which melts at a moderate red heat, and crystallizes as it cools. Accord- ing to Berzelius, it consists of 84.3 metal -j- 15.7 oxygen. 3. The tritoxide, or an- timonious acid, is the immediate product of the combustion of the metal, called of old from its fine white colour, the argen- tine flowers of antimony. It may also be formed by digesting hot nitric acid on an- timony. When fused with one-fourth of antimony, the whole becomes deutoxide. It forms the salts called antimonites with the different bases. According to Berze- lius, the tritoxide consists of about 80 me- tal -f 20 oxygen. 4. The peroxide, or antimonic acid, is formed, when the metal in powder is ignited along with six times its weight of nitre in a silver crucible. The excess of potash and nitre being af- terwards separated by hot water, the and- ANT ANT moniatc of potash is then to be decomposed by muriatic acid, when the insoluble anti- monic acid of a straw colour will be ob- tained. Nitro-muriatic acid likewise con- verts the metal into the peroxide. Though insoluble in water, it reddens the vegeta- ble blues. It does not combine with acids. At a red heat oxygen is disengaged, and antimonions acid results. Berzelius infers its composition to be 73.5 metal + 26.5 oxygen. It is difficult to reconcile the above three portions of oxygen to one prime equivalent for antimony. The num- ber 11. gives the best approximation to Ber- zelius's analyses. We shall then have the In 100 parts. Protoxide Ilffietal4-loxy.or91.f4- 3.* Deutoxide 11 + 2 84.6+15.4 Tritoxide 11 -j- 3 7U6+21.4 Peroxide 11 +4 73.4+26.6. The second and fourth numbers agree perfectly with experiment ; the first ox- ide is too imperfectly known to enter into the argument ; and the third number, though it indicates a little more oxyg'en than Berzclius assigns, gives less than Proust. Chlorine gas and antimony combine with combustion, and a bichloride results. This was formerly prepared by distilling a mixture of two parts of corrosive subli- mate with one of antimony. The sub- stance which came over having a fatty consistence, was called butter of antimony. It is frequently crystallized in four-sided prisms. It is fusible and volatile at a mo- derate heat ; and is resolved by water alone into the white oxide and muriatic acid. Being a bichloride, it is eminently corrosive, like the bichloride of mercury, from which it is formed. It consists of 45.7 chlorine + 54.3 antimony, according to Dr. John Davy's analysis, when the com- position of the sulphuret is corrected by its recent exact analysis by Berzelius. But 11. antimony + 2 primes chlorine = 9.0, give the proportion per cent of 44.1 + 55.5; a good coincidence, if we consider the circuitous process by which Dr. Da- vy's analysis was performed. Three analysts have found 30, 33, and 35 to 100 of metal. Berzelius admits that there may be a slight error in his numbers. The on- ly important alloys of antimony are those of lead and tin ; the former constitutes type metal, and contains about one-six- teenth of antimony ; the latter alloy is em- ployed for making the plates on which music is engraved. The salts of antimony are of two diffe- rent orders; in the first, the deutoxide acts the part of a salifiable base ; in the second, the tritoxide and peroxide, act the part of acids, neutralizing the alkaline and other bases, to constitute the antimo- nites and antimoniates. The only distinct combination of the first order entitled to our attention, is the triple salt called tartrate of potash and an- timony, or tartar emetic, and which, by M. Gay-Lussac's new views, would be styled cream-tartrate of antimony. This constitutes a valuable and powerful medi- cine, and therefore the mode of preparing it should be correctly and clearly defined. As the dull white deutoxide of antimony is the true basis of this compound salt, and as that oxide readily passes by mis- management into the tritoxide or antimo- nious acid, which is altogether unfit for the purpose, adequate pains should be taken to guard against so capital an error. In former editions of the British Pharma- copoeias, the glass of antimony was pre- scribed as the basis of tartar emetic. More complex and precarious formulae have been since introduced. The new edition of the Pharmacopce Francaise has given a recipe, which appeal's, with a slight change of proportions, to be unexception- able. Take of the sulphuretted vitreous oxide of antimony levigated, and acidulous tartrate of potash, equal parts. Form a powder, which is to be put into an earthen or silver vessel, with a sufficient quantity of pure water. Boil the mixture for half an hour, adding boiling water from time to time ; filter the hot liquor, and evapo- rate to dryness in a porcelain capsule; dissolve in boiling water the result of the evaporation, evaporate till the solution ac- quires the spec. grav. 1.161, and then let parts of corrosive sublimate, and one of it repose, that crystals be obtained, which, .i_ii' ._i- i Vv this nrnrpss \vi11 hp rmrf "Kv jnntli#i- metallic antimony, are the equivalent proportions for making butter of antimo- ny. Iodine and antimony combine by the aid of heat into a solid iodide, of a dark-red colour. The phosphuret of this metal is obtained by fusing it with solid phosphoric acid. It is a white semi-crys- talline substance. The sulphuret of anti- mony exists abundantly in nature. See OIIKS of ANTIMONY. It consists, according to Berzelius, of 100 antimony + 37.25 sulphur. The proportion given by the equivalent ratio is 100 + 36.5. Other VOL. T. [ 23 ] by this process, will be pure. By another recipe, copied, with some alteration frora Mr. Phillips's prescription, into the ap- pendix of the French Pharmacopoeia, a subsulphate of antimony is formed first of all, by digesting two parts of sulphuret of antimony in a moderate heat, with three parts of oil of vitriol. This insoluble sub- sulphate be'ing well washed, is then di- gested in a quantity of boiling water, with its own weight of cream of tartar, and eva- porated to the density 1.161, after which it is filtered hot. On cooling, crystals of ANT ANT the triple tartrate are obtained. One might imagine, that there is a chance of obtaining by this process, a mixture of sul- phate of potash, and perhaps of a triple sulphate of antimony, along with the tartar emetic. Probably this does not happen, for it is said to yield crystals, very pure, very white, and without any mixture Whatever. Pure tartar emetic is in colourless and transparent tetrahedrons or octohedrons. It reddens litmus. Its taste is nauseous and caustic. Exposed to the air, it efflo- resces slowly. Boiling water dissolves half its weight, and cold water a fifteenth part. Sulphuric, nitric, and muriatic acids, when poured into a solution of this salt, precipitate its cream of tartar; and soda, potash, ammonia, or their carbonates, throw down its oxide of antimony. Bary- tes, strontites, and lime waters, occasion not only a precipitate of oxide of antimo- ny, like the alkalis, but also insoluble tar- trates of these earths. That produced by the alkaline hydrosulphurets, is wholly formed of kermes ; while that caused by sulphuretted hydrogen, contains both kermes and cream of tartar. The decoc- tions of several varieties of cinchona, and of several bitter and astringent plants, equally decompose tartar emetic ; and the precipitate then always consists of the ox- ide of antimony, combined with the vege- table matter and cream of tartar. Physi- cians ought therefore to beware of such incompatible mixtures. When tartar eme- tic is exposed to a red heat, it first black- ens, like all organic compounds, and af- terwards leaves a residuum of metallic an- timony and subcarbonate of potash. From this phenomenon and the deep brownish- red precipitate, by hydrosulphurets, this antimonial combination may readily be re- cognized. r i n ie precipitate may further be dried on a filter, and ignited with black flux, when a globule of metallic antimony will be obtained. Infusion of galls is an active precipitant of tartar emetic. This salt, in an undue dose, is capable of acting as a poison. The best antidotes are demulcent drinks, infusions of bark, tea, and sulphuretted hydrogen water, which instantly converts the energetic salt into a relatively mild sulphuret : ano- dynes are useful afterwards. The powder of tai-tar emetic, mixed with hog's lard, and applied to the skin of the human bo- dy, raises small vesications. The composition of this salt, according lo M. Thenard, is 35.4 acid, o9.6 oxide, 16.7 potash, and 8.2 water. The presence of the latter ingredient is obvious, from the undisputed phenomenon of efflores- cence. If we adopt the new views of M. Gay-Lussac, this salt may be a compound of a prime equivalent of tartar == 23,825, with a prime equivalent of deutoxide of antimony = 13. On this hypothesis we would have the following proportions : 2 primes acid = 16,75 45.4 1 prime potash = 5.95 16.2 1 prime water = 1.125 3.1 1 oxide of antimony = 13.00 35.S 36.825 100.0 But very little confidence can be reposed in such atomical representations. The deutoxide seems to have the pro- perty of combining with sulphur in vari- ous proportions. To this species of com- pound must be referred the liver of anti- mony, glass of antimony, and crocus metal- lorum of the ancient apothecaries. Sul- phuretted hydrogen forms, with the deu- toxide of antimony, a compound which possessed at one time great celebrity in medicine, and of which a modification has lately been introduced into the art of cal- ico printing. By dropping hydrosulphu- ret of potash, or of ammonia, into the cream-tar trate, or into mild muriate of an- timony, the hydrosulphuret of the metal- lic oxide precipitates of a beautiful deep orange colour. This is kermes mineral. Cluzel's process for obtaining a fine ker- mes, light, velvety, and of a deep purple- brown, is the following : one part of pul- verized sulphuret of antimony, 22| parts of crystallized subcarbonate of soda, and 200 parts of water, are to be boiled to- gether in an iron pot. Filter the hot li- quor into warm earthen pans, and allow them to cool very slowly. At the end of 24 hours the kermes is deposited. Throw it on a filter, wash it with water which haJ been boiled and then cooled out of contact with air. Dry the kermes at a temperature of 85, and preserve in cork- ed phials. Whatever ma} be the process employed, by boiling the liquor after cool- ing and filtration, on new sulphuret of an- timony, or upon that which was left in the former operation, this new liquid will de- posiie, on cooling, a new quantity of ker- mes. Besides the hydrosulphuretted oxide of antimony, there is formed a sulphuret. ted hydrosulphuret of potash or soda. Consequently, the alkali seizes a portion of the sulphur from the antimonial sulphu- ret, water is decomposed, and whilst a portion of its hydrogen unites to the alka- line sulphuret, its oxygen, and the other portion of its hydrogen, combine with the sulphuretted antimony. It seems, that the resulting kermes remains dissolved in the sulphuretted hydrosulphuret of potash or soda; but as it is less soluble in the cold than the hot, it is partially precipitated by refrigeration. If we pour into the super- natant liquid, after the kermes is deposi- ted and removed, any acid, as the dilute ANT APL nitric, sulphuric, or muriatic, we decom- pose the sulphuretted hydrosulphuret of potash or soda. The alkaline base being laid hold of, the sulphuretted hydrogen and sulphur to which they were united are set at liberty; the sulphur andkermes fall together, combine with it, mid form an orange-coloured compound, called the golden sulphuret of antimony. It is a hy- droguretted sulphuret of antimony. Hence, when it is digested with warm muriatic acid, a large residuum of sulphur is ob- tained, amounting sometimes to 12 per cent. Kermes is composed by Thenard, of 20.3 sulphuretted hydrogen, 4.15 sul- phur, 72 76 oxide of amimony, 2.79 water and loss ; and the golden sulphuret con- sists of 17.87 sulphuretted hydrogen, 68.3 oxide of antimony, and 12 sulphur. By evaporating the supernatant kermes liquid, and cooling, crystals form, which have been lately employed by the calico printer, to give a topical orange. These crystals are dissolved in water, and the so- lution being thickened with paste or gum, is applied to cloth in the usual way. When the cloth is dried, it is passed through a dilute acid, when the orange precipitate is deposited and fixed on the vegetable fibres. An empirical antimonial medicine, called James's powder, has been much used in this country. The inventor called it his fever powder, and was so successful in his practice with it, that it obtained very great reputation, which it still in some measure retains. Probably, the success of Dr. James was in great measure owing to his free use of the bark, which he always gave as largely as the stomach would bear, as soon as he had completely evacu- ated the primje vix by the use of his antimo- nial preparation, with which at first he used to combine some mercurial. His spe- cification, lodged in chancery, is as follows: " Take antimony, calcine it with a con- tinued protracted heat, in aflat* unglazed, earthen vessel adding to it from time to time a sufficient quantity of any animal oil and salt, well dephlegmated ; then boil it in melted nitre for a considerable time, and separate the powder from the nitre by dissolving it in water." The real recipe has been studiously concealed, and a false one published in its stead. Different for- mulae have been offered for imitating it. That of Dr. Pearson furnishes a mere mix- ture of an oxide of antimony, with phos- phate of lime. The real powder of James, according to this chemist, consists of 57 oxide of antimony, with 43 phosphate of lime. It seems highly probable that super- phosphate of lime would act on oxide of antimony, in a way somewhat similar to cream of tartar, and produce a more che- mical combination, than what can be de- rived from a precarious ustulation and cal- cination of hartshorn shavings and sul- phuret of amimony, in ordinary hands. The antimonial medicines are powerful deobstruents, promoting particularly the cuticular discharge. The union of this metallic oxide with sulphuretted hydro- gen, ought undoubtedly to favour its me- dicinal agency in chronic diseases of the skin. The kermes deserves more credit than it has hitherto received from British physicians. The compounds formed by the antimo- nious and antimonic acids, with the bases, have not been applied to any use. Muriate of barytes may be employed as a test for tartar emetic. It will show, by a precipi- tate insoluble in-niiric acid, if sulphate of potash be present. If the crystals be re- gularly formed, mere tartar need not be suspected,* For its ores, and the reduction of the metals, see OIIES. ANTS. See Acin (FOUMIC). * APATITE. Phosphate of lime. This mineral occurs both massive and crystal- lized. The crystals are six-sided prisms, low, and sometimes passing into the six- sided table. Lateral edges, frequently truncated, and the faces smooth. Lustre splendent. Translucent, rarely transpa- rent. Scratched by fluor spar. Brittle. Colours, white, wine-yellow, green, and red. Sp. grav. 3.1. Phosphoresces on coals. Electric by heat and friction. Con- sists of 53.7* lime -f- 46.25 phosphoric acid, by Klaproth's analysis of the variety called asparagus stone. It occurs in pri- mitive rocks; in the tin veins of the gra- nite of St. Michael's Mount, Cornwall; near Chudleigh in Devonshire ; at Nantes in France ; in St. Gothard, and in Spain ; and with molybdena in granite, near Col. beck, Cumberland. Phosphorite is mas- sive, forming great beds in the province of Estremadura. Yellowish-white colour. Dull or glimmering lustre. Semi-hard. Fracture, imperfect curved foliaied. Brit- tle. Sp. grav. 2.8. Phosphorescent with beat. Its composition by Pelletier is 59 lime, 34 phosphoric acid, 1 carbonic acid, 2.5 fluoric acid, 2 silica, 1 oxide of iron, and 0.5 muriatic acid.* * APHRITK. Earth foam ; Schaumerde. This carbonate of lime occurs usually in a friable state; but sometimes solid. Co- lour, almost silver-white. Massive, or in fine particles. Shining lustre, between semi-metallic and pearly. Fracture, curved foliated. Opaque ; soils a little. Very soft, and easily cut. Feels fine and light. It is usually found in calcareous veins, at Gcra in Misnia, and Eisleben in Thuringia. It consists, by Bucholz, of 51.5 lime, 39 acid, 1 water, 5.7 silica, 3. 3 oxide of iron.* * APIOXE. This is commonly consider* AQU ed to be a variety of the garnet; bnt the difference between these minerals is this : the planes of the aplome dodecahedrons are striated parallel with their smaller di- agonal, which, according to Haiiy, indi- cates the primitive form to be a cube, and not. a dodecahedron. Its colour is deep orange-brown. It is opaque, and harder than quartz. Sp. grav. is much less than garnet, viz. 3.44. It consists, by Laugier's analysis, of 40 silica, 20 alumina, 14.5 lime, 14 oxide of iron, 2 oxide of manga- nese, 2 silica and iron. It is fusible into a black glass, while garnet fuses into a black enamel. It is found on the river Lena in Siberia, and also in New Holland.* * AFOPHYLLITE. lchth\ ophthalmite. Fisheyestone. It is found both massive and crystallized. It occurs in square prisms, whose solid angles are sometimes replaced by triangular planes, or the prisms are terminated by pyramids con- sisting of 4 rhomboidal planes. Structure lamellar; cross fracture, fine grained, un- even. External lustre, splendent, and pe- culiar; internal, glistening and pearly. Semi-transparent, or translucent. Mode- rately hard, and easilv broken. Sp. gr. 2.49. It exfoliates, then froths, and melts into an opaque bead before the blow-pipe. It consists of 51 silica, 28 lime, 4 potash, 17 water. Vauqrelin. It is found in the iron mine of Utoe in Sweden; at the cop- per mine of Fahlun ; at Arendahl, Faroe, the Tyrol; and I)r MacCulloch met with a solitary crystal in Dunveghn, in the Isle of Sky.* APPARATUS. See LAF.OIIATORY. APPLES. See ACID (MALIC). APYROUS. Bodies which sustain the ac- tion of a strong heat for a considerable time, without change of figure or other properties, have been called apyrous ; but the word is seldom used in the art of chemistry. It is synonymous with re- fractory. A a' AFORTTS. This name is given to a weak and impure nitric acid, commonly used in the arts. It is distinguished by the terms double and single, the single being only half the strength of the other. The artists who use these acids call the more concentrated acid, which is much stronger even than the double aquafortis, spirit of nitre. This distinction appears to be of some utility, and is therefore not im- properly retained by chemical writers. See ACID (NITRIC-). * Ao.tr A MARIXE. See BERYT.* AauA RERIA, or RKRIS. This acid, be- ing compounded of a mixture of the nitric and muriatic acids, is now termed by chemists nitro-muriatic acid. AQ.UA VITTK. Ardent spirit of the first distillation has been distinguished in com- merce by this name. The distillers of ARC malt and molasses spirits call it low wines. AU.UTLA ALBA. One of the names given to the combination of muriatic acid and mercury in that state, which is more com- monly known by the denomination of merciirius fluids, calomel, or mild muriate of mere in if. ARABIC (Gusr). This is reckoned the purest of gums, and does not greatly dif- fer from g-uni Senegal, vulgarly called gum seneca, which is supposed to be the strongest, and is on this account, as well as its greater plenty and cheapness, most- ly used by calico printers and other ma- nufacturers. The gums of the plum and cherry -tree have nearly the same qualities as gum arabic. All these substances fa- cilitate the mixture of oils with water. ARAB K LASDS. It is a problem in che- mistry, and by no means one of the least importance to society, to determine what are the requisites which distinguish fruit- ful lands from such as are less productive. See SOILS, and ANALYSIS of SOILS. ARKOR DIANTK. See SILVER. AUCHIL, ARCHILL.*, KOCKLLA, ORSEILLE. A whitish lichen, growing upon rocks in the Canary and Cape Verd Islands, which yields a rich purple tincture, fugitive in- deed, but extremely beautiful. This weed is imported to us as it is gathered : those who prepare it for the use of the dyer, grind it betwixt stones, so as thoroughly to bruise, but not to reduce it into pow- der, and then moisten it occasionally with a strong spirit of urine, or urine itself mixed with quicklime : in a few days it acquires a purplish-red, and at length a blue colour; in the first state it is called archil, in the latter lacmus or litmus. The dyers rarely employ this drug by itself, on account of its dearness, and the perishableness of its beauty. The chief use they make of it is for giving a bloom to other colours, as pinks, &c. This is effected by passing 1 the dyed cloth or silk through hot water slightly impregnated with the archil. The bloom thus commu- nicated soon decays upon exposure to the air. Mr. Hellot informs us, that by the addition of a little solution of tin, this drug gives a durable dye ; that its colour is at the same time changed toward a scarlet; and that it is the move permanent, in pro- portion as it recedes the more from its natural colour. Prepared archil very readily gives out its colour to water, to volatile spirits, and to alcohol; it is the substance principally made use of for colouring the spirits of thermometers. As exposure to the air destroys its colour upon cloth, the exclu- sion of the air produces a like effect in those hermetically sealed tubes, the spirits of large thermometers becoming; in a few ARG- ARS years colourless. The Abbe* Nollet ob- serves, (in the French Memoirs for the year 1742), that the colourless spirit, upon breaking the tube, soon resumes its co- lour, and this for a number of times suc- cessively ; that a watery tincture of ar- chil, included in the tubes of thermome- ters, lost its colour in three days ; and that in an open deep vessel, it became colourless at the bottom, while the upper part retained its colour. A solution of archil in water, applied on cold marble, stains it of a beautiful violet or purplish-blue colour, far more durable than the colour which it communicates to other bodies. M. du Fay says, he has seen pieces of marble stained with it, which in two years had suffered no sensi- ble change. It sinks deep into the mar- ble, sometimes above an inch, and at the same time spreads upon the surface, un- less i he edges be bounded by wax or some similar substance. It seems to make the marble somewhat more brktle. There is a considerable consumption of an article of this kind, manufactured in Glasgow by Mr- Mackintosh. It is much esteemed and sold by the name of cud- bear We ha^e seen beautiful specimens of silk thus dyed, the colours of which were said to be very permanent, of va- rious shades, from pink and crimson to a bright mazarine blue. Litmus is likewise used in chemistry as a test, either staining paper with it, or by infusing it in water when it is very com- monly, but with great impropriety, called tincture of turnsole. The persons by whom this article was prepared, formerly gave it the name of turnsole, pretending that it was extracted from the turnsole, heliotro- pium tricoccum, in order to keep its true source a secret. The tincture should not be too strong, otherwise it will have a violet tinge, which, however, may be re- moved by dilution. The light of the sun turns it red even in close vessels. It may be made with spirit instead of water. This tincture, or paper stained with it, is presently turned red by acids : and if it be first reddened by a small quantity of vinegar, or some weak acid, its blue co- lour will be restored bv an alkali. f Litmus gives out its colouring matter but feebly to strong alcohol ; and watery infusions do not keep. To preserve it in a state for use, an infusion in weak spirit is best.f * AUCTTZITE. See WERSTERITE.* An DENT SPIRIT. See ALCOHOL. * ARF.NOATK. See PISTACITE.* AREOMETER. See HTDKOMETER. ARGAL. Crude tartar, in the state in which it is taken from the inside of wine vessels, is known in the shops by this name. OF AMMONIA, fulminating silver. ARGILLACEOUS EARTH, or ALUMIXA. * AIIGILLITX. See CLAY-SLATK.* AHOMATICS. Plants which possess ft fragrant smell united with pungency, and at the same time are warm to the taste, are called aromatics. Their peculiar fla- vour appears to reside in their essential oil, and rises in distillation either with wa- ter or spirit. ARRACK. A spirituous liquor imported from the East Indies. It is chiefly manu- factured at Batavia, and at Goa upon the Malabar coast. * AURAGON-TTE. This mineral occurs massive, in fibres of a silky lustre ; and in the form of fibrous branches, diverging 1 from a centre, Flos-feni. It is frequently crystallized in what appear at first sight to be regular six-sided prisms. On close inspection a longitudinal crack will be ob- served down each lateral face. It occurs also in elongated octohedrons. Lustre glassy, fracture foliated and fibrous. Co- lours greenish and pearl-gray ; often violet and green in the middle ; and arranged in the direction of the fibres, so that the longitudinal fibres are green, the trans- verse violet-blue. Double cleavage translucent refracts doubly scratches calcareous spar, and sometimes even glass brittle sp. grav. 2.90. It consists of carbonate of lime, with occasionally a little carbonate of strontites. It is found in Arragon 1-n Spain, at Leogany in Salz- burg, at Marienberg in Saxony, and Ster- zing in the Tyrol. In the cavities of Ba- salt near Glasgow. The finest specimens of Flos-ferri ramifications, come from the mines of Eisenerz in Stii-ir. Beautiful spe- cimens have been also found in the Duf- ton lead mines in England, i.i the work- ings of an old coal mine, called Lufton- hill pit near Durham. It also occurs in the trap rocks of Scotland.* ARSEXTC, in the metallic state, is of a bluish white colour, subject to tarnish, and grows first yellowish, then black, by exposure to air. It is brittle, and when broken exhibits a laminated texture. Its specific gravity is 5.763. In close vessels it sublimes entire 'at 356 F. but burns with a small flame if respirable air be pre- sent. The arsenic met with in commerce has the form of a white oxide. It is brought chiefly from the cobalt works in Saxony, where zarFre is made. Cobalt ores con- tain much arsenic, which is driven off by long torrefaction. The ore is thrown into a furnace resembling a baker's oven, with a flue, or horizontal chimney, nearly two hundred yards long, into which the fumes pass, and are condensed into a grayish or blacki&h powder. This is refined by a A11S ARS second sublimation in close vessels, with a little potash, to detain the impurities. As the heat is considerable, it melts the sublimed flowers into those crystalline masses which are met with in commerce. See ACID (ARSEMO s). The metal may be obtained from this, either by quickly fusing it tog-ether with twice its weight of soft soap and an equal quantity of alkali, and pouring it out, when fused, into a hot iron cone ; or by mixing it in powder with oil, and exposing it in a matrass to a sand heat. This pro- cess is too offensive to be perform^, ex- cept in the open air, or where a current of air carries off the fumes. The decom- posed oil first rises; and the arsenic is af- terwards sublimed, in the form of a flaky metallic substance. It may likewise be obtained by mixing two parts of the ar- senious acid with one of black flux ; put- ting the mixture into a crucible, with another inverted over it, and luted to it with clay and sand ; and applying a red heat to the lower crucible. The metal will be reduced, and line the inside of the upper crucible. It is among the most combustible of the metals, burns with a blue flame, and gar- lic smell, and sublimes in the state of ar- senious acid. j- A very striking characteristic of this metal is, that it sublimes before it fuses.f Concentrated sulphuric acid does not attack arsenic when cold but if it be boiled upon this metal, sulphurous acid gas is emitted, a small quantity of sulphur sublimes, and the arsenic is re'duced to an oxide. Nitrous acid readily attacks arsenic, and converts it into arsenious acid, or, if much be employed, into arsenic acid. Boiling muriatic acid dissolves arsenic, but affects it very little when cold. This solution affords precipitates upon the ad- dition of alkalis. The addition of a little nitric acid expedites the solution ; and this solution, first heated and condensed in a close vessel, is wholly sublimed into a thick liquid, formerly termed butter of arsenic. Thrown in powder into chlorine gas, it burns with a bright white flame, and is converted into a chloride. None of the earths or alkalis act upon it, unless it be boiled a long while in fine pov/der, in a large proportion of alkaline solution. Nitrates detonate with arsenic, convert it into arsenic acid, and this, combining with the base of the nitrate, forms an arseniate, that remains at the bottom of the vessel. Muriates have no action upon it ; but if three parts of chlorate of potash be mixed with one part of arsenic in fine powder, which must be done with great precaution, and a very light hand, a very small quan- tity of this mixture, placed on an anvil, and struck with a hammer, will explode with flame and a considerable report ; if touch- ed with fire, it will burn with considerable rapidity; and if thrown into concentrated sulphuric acid, at the instant of contact a flame rises into the air like a flash of light- ning, which is so bright as to dazzle the eye. Arsenic readily combines with sulphur by fusion and sublimation, and forms a yellow compound called orpiment, or a red called realgar. The nature of these, and their difference, are not accurately known, but Fourcroy considers ihe first as a com- bination of sulphur with the oxide, and the second as a combination of sulphur with the metal itself, as he found the red sulphuret converted into the yellow by the action of acids. Arsenic is soluble in fat oils in a boiling heat ; the solution is black, and has the consistence ot an ointment when cold. Most metals unite with arsenic ; which exists in the metallic state in such alloys as possess the metallic brilliancy. * Iodine and arsenic unite, forming an iodide of a dark purple-red colour, pos- sessing the properties of an acid. It is soluble in water, and its solution forms a soluble compound with potash. Arsenic combines with hydrogen into a very nox- ious compound, called arsenuretted hy- drogen gas. To prepare it, fuse in a co- vered crucible, 3 parts of granulated tin, and 1 of metallic arsenic in powder; and submit this alloy, broken in pieces, to the action of muriatic acid in a glass retort. On applying a moderate heat, the arsenu- retted hydrogen comes over, and may be received in a mercurial or water pneuma- tic trough. Protomuriate of tin remains in the retort. When 1 of arsenic is used for 15 of tin, the former metal is entirely carried oft' in the evolved hydrogen. 100 parts of this gas contain 140 of hydrogen, as is proved by heating it with tin. Its specific gravity, according to Sir H. Davy, is 0.5552 ; according to Trommsdorf, 0.5293. Strorneyer states, that by a cold of 22, it condenses into a liquid. Ex- ploded with twice its bulk of oxygen, wa- ter and oxide of arsenic are formed. When arsenuretted hydrogen issuing from a tube is set on fire, it deposites a hydruret of ar- senic. Sulphur, potassium, sodium, and tin, decompose this gas, combine with its metal, and in the case of sulphur, sulphu-> retted hydrogen results. By subtracting from the specific gravity of the arsenuret- ted gas, that of hydrogen gas \-^* we have the proportion of arsenic present; 0.55520 0.09716 = 0.45804 = the arsenic in 100 measures of arsenuretted hydrogen ; which gives the proportion by weight of about 6 arsenic to 1 hydrogen ; but Stromeyer's ASA ASB analysis by nitric acid gives about 50 ar- senic to 1 hydrogen, which is probably much nearer the true composition, A prime equivalent of hydrogen is to one of arsenic as 1 to 76 ; and 2 consequently as 1 to 38. Gehlen fell a victim to his re- searches on this gas ; and therefore the new experiments requisite to elucidate its constitution must be conducted with cir- cumspection. If chlorine be added to a mixture of arsenuretted and sulphuretted hydrogen, the bulk diminishes, and yellow coloured flakes are deposited. Concen- trated nitric acid occasions an explosion in this gas, preceded by nitrous fumes ; but if the acid be diluted, a silent decom- position of the gas is effected. The den- sity of the hydrogen in this compound gas is 0,09716. Therefore, by Stromejer's analysis, we have this proportion to cal- culate the specific gravity of the gas, 2.19 : 0.09716 : : (2.19 + 106) : 4.827 ; a quantity nearly 9 times greater than what experimen has given. This gas extinguishes flame, and instant- ly destroys animal life. Water has no ef- fect upon it. From the experiments of Sir H. Davy and MM. Gay-Lussac and Thenard, there appears to be a solid com- pound of hydrogen and arsenic, or a hy- druret. It is formed by acting with the negative pole of a voltaic battery on arae- nic plunged in water. It is reddish-brown, without lustre, taste, and smell. It is not decomposed at a heat approaching to cherry-red ; but at this temperature it ab- sorbs oxygen ; while water and arsenious acid are formed, witii the evolution of heat and light. The proportion of the two constituents is not known.* Arsenic is used in a variety of arts. It enters into metallic combinations, wherein a white colour is required. Glass manu- facturers use it ; but its effect in the com- position of glass does notseemto be clear- ly explained. Orpiment and realgar are used as pigments. See Acins (AIISEMC, and ARSETHOCS). As\po3TiDA is obtained from a large um- belliferous plant growing in Persia. The root resembles a large parsnep externally, of a black colour : on cutting it transverse- ly, the assafcetida exudes in form of a white thick juice, like cream ; which, from ex- posure to the air, becomes yellower and yellower, and at last of a dark-brown co- lour. It is very apt to run into putrefac- tion ; and hence those who collect it care- fully defend it from the sun. The fresh juice has an excessively strong smell, which grows weaker and weaker upon keeping : a single dram of the fresh fluid juice smells more than a hundred pounds of the dry asafoetida brought to us. The Persians are commonly obliged to hire ships on purpose for its carnage, as scarce- ly any one will receive it along with other commodities, its stench infecting every thing that comes near it. 'I he common asafoetida of the shops is of a yellowish or brownish colour, unctu- ous and tough, of an acrid or biting taste, and a strong disagreeable smell, resem- bling that of garlic. From four ounces Neumann obtained, by rectified spirit, two ounces six drams and a half of resi- nous extract ; and afterward, by water, three drams and half a scruple of gummy extract; about six drams and a scruple of earthy matter remaining undissolved. Oa applying water at first, he gained, from four ounces, one ounce three scruples and a half of gummy extract. Asafoetida is administered in nervous and hysteric affections, as a deobstruent, and sometimes as an anthelmintic. A tinc- ture of it is kept in the shops, and it en- ters into the composition of the compound galbanum pill of the London college, the gum pill of former dispensatories. * ASBESTOS or ASBESTUS. A mineral of which there are five varieties, all more or less flexible and fibrous. 1. Amianthus occurs in very long, fine, flexible, elastic fibres, of a white, greenish, or reddish colour. It is somewhat unctu- ous to the touch, has a silky or pearly lus- tre, and is slightly translucent. Sectile ; tough ; sp. grav. from 1 to 2.3. Melts with difficulty before the blow-pipe, into a white enamel. It is usually found ia serpentine ; in the Tarentaise in Savoy ; in long and beautiful fibres, in Corsica ; near Bareges, in the Pyrenees ; in Dau- phiny and St. Gothard ; at St. Keverne. Cornwall ; at Portsoy, Scotland ; in mica slate at Glenelg, Invernesshire, and near Durham. It consists of 59 silex, 25 mag- nesia, 9.5 lime, 3 alumina, and 2.25 oxide of iron.* The ancients manufactured cloth out of the fibres of asbestos, for the purpose, it is said, of wrapping up the bodies of the dead, when exposed on the funeral pile. Several moderns have likewise succeeded in making this cloth ; the chief artifice of which seems to consist in the admixture of flax and a liberal use of oil ; both which substances are afterwards consumed by exposing the cloth for a certain time to a red heat. Although the cloth of asbestos, when soiled, is restored to its primitive whiteness by heating in the fire ; it is found, nevertheless, by several authentic experiments, that its weight diminishes by such treatment. The fibres of asbestos, exposed to the violent heat of the blow- pipe, exhibit slight indications of fusion ; though the parts, instead of running to- gether, moulder away, and part fall down, while the rest seem to disappear before the current of air. Ignition impairs the ASP ASS flexibility of asbestos in a slight de- gree. * 2. Common Asbestus occurs in masses of fibres of a dull greenish colour, and of a somewhat pearly lustre. Fragments splintery. It is scarcely flexible, and great- ly denser than amianthus. It is slightly unctuous to the touch. Sp. grav 2.7. Fuses with difficulty into a grayish-black scoria. It is composed of 63.9 silica, 16 magnesia, 12.8 lime, 6 oxide of iron, and 1.1 alumina. It is more abundant than amianthus, and is found usually in serpen- tine, as at Portsoy, the Isle of Anglesea, and the Lizard in Cornwall. It wa"s found in the limestone of Glentilt, by Dr, Yl'Cul- loch, in a pasty state, but it soon hardened by exposure to air. 3. Mountain Leather consists not of parallel fibres like the preceding, but in- terwoven and interlaced so as to become tough. When in very thin pieces it is called mountain paper. Its colour is yel- lowish-white, and its touch meagre. It is found at Wanlockhead, iu Lanarkshire. Its specific gravity is uncertain. 4. Mountain Cork, or Elastic *flsbestus, is, like the preceding, of an interlaced fibrous texture ; is opaque, has a meagre feel and appearance, not unlike common cork, and like it too, is somewhat elastic. It swims on water. Its colours are, white, gray, and yellowish-brown. Receives an impression from the nail ; very tough ; cracks when handled, and melts with dif- ficulty before the blow-pipe. Sp. grav. from 0.68 to 0.99. Tt is composed of sili- ca 62, carbonate of lime 13, carbonate of magnesia 23, alumina 2.8, oxide of iron 3. 5. Mountain Wood. Ligniform asbestus. Ts usually massive, of a brown colour, and having the aspect of wood. Internal lus- tre glimmering. Soft, sectile and tough ; opaque; feels meagre; fusible into a black slag. Sp. grav. 2.0. It is found in the Tyrol; Dauphiny ; and in Scotland, at Glentilt, Portsoy, and Kildrumie.* ASHCS. The fixed residue of combusti- ble substances, which remains after they have been burned, is called ashes. In chemistry it is most commonly used to de- note the residue of vegetable combustion. * ASPABAGIX. White transparent crys- tals, of a peculiar vegetable principle, \vhich spontaneously form in asparagus juice \vhich has been evaporated to the consistence of sirup. They are in the form of rhomboidal prisms, hard and brittle, having a cool and slightly nauseous taste. They dissolve in hot water, but sparingly in cold water, and not at all in alcohol. On being heated they swell, and emit pen- etrating vapours, which affect the eyes and nose like wood-smoke. Their solution does not change vegetable blues; nor is it affected by hydrosulphuret of potash, oxalate of ammonia, acetate of lead, or in- fusion of galls. Lime disengages ammonia from it; though none is evolved by tritu- rating it with potash. The asparagusjuice should be first heated to coagulate the al- bumen, then filtered and left to sponta- neous evaporation for 15 or 20 days. Along with the asparagin crystals, others in needles of little consistency appear, analogous to mannite, from which the first can be easily picked out. Vauquelin and Robiquet. Annales de Chimie, vol. 55. and Nicholson's Journal, 15.* ASPHALTTTM. This substance, likewise called Bitumen Judaicum, or Jews' Pitch, is a smooth, hard, brittle, black or brown substance, which breaks with a polish, melts easily when heated, and when pure burns without leaving any ashes. It is found in a soft or liquid state on the sur- face of the Dead Sea, but by age grows dr\ and hard. The same kind of bitumen is likewise found in the earth in other parts of the world ; in China America, particularly in the island of Trinidad ; and some parts of Europe, as the Carpathian hills, France, Neufchattel, &c. Its speci- fic gravity, according to Boyle, is 1.400,. to Kirvvan, from 1.07 to 1.65. A specimen from Albania, of the specific gravity of 1.205, examined by Mr. Klaproth, was found to be soluble only in oils and in ether. Five parts of rectified oil of petro- leum dissolved one of the asphaltum, without heat, in 24 hours. Analyzed in the dry way, 100 grains afforded 32 of bi- tuminous oil, 6 of water faintly ammonia- cal 30 of charcoal, 7 of silex, 7$ of alu- mina, $ of lime, 1 oxide of iron, oxide of manganese, and 36 cubic inches of hy- drogen gas. According to Neumann, the asphaltum of the shops is a very different compound from the native bitumen; and varies, of course, in its properties, according to the nature of the ingredients made use of in forming it. On this account, and probably from other reasons, the use of asphaltum, as an article of the materia medica, is al- most totally laid aside. * The Egyptians used asphaltum in em- balming, under the name of mumia mine- ralis for which it is -well adapted. It was used for mortar at Babylon.* ASSAY, or ESSAY. This operation con- sists in determining the quantity of valua- ble or precious metal contained in any In the Mem. of the Academy of Sci- ences of Paris for 1778, there is an analy- sis of the wa'er of this sea by Messrs. Mac- quer, Lavoisier, and Sage ; by which it appears to contain 22 per cent of muriate of magnesia, 16A of muriate of lime, and 6-]- of muriate of soda. Its specific gravity- is 1.25. It is limpid, and without smell. ASS ASS mineral or metallic mixture, by analyzing a small part thereof. The practical differ- ence between the analysis and the assay of an ore, consists in this : The analysis, if properly made, determines the nature and quantities of all the parts of the com- pound ; whereas, the object of the assay consists in ascertaining 1 how much of the particular metal in question may be con- tained in a certain determinate quantity of the material under examination. Thus, in the assay of gold or silver, the baser metals are considered as of no value or consequence; and the problem to be re- solved is simply, how much of each is con- tained in the ingot or piece of metal in- tended to be assayed. The examination of metallic ores may be seen under their respective titles ; the present article will therefore consist of an account of the as- saying of gold and silver. To obtain gold or silver in a state of pu- rity, or to ascertain the quantity of alloy it may contain, it is exposed to a strong heat, together with lead, in a porous cru- cible. This operation is called cupellation, and is performed as follows : The preci- ous metal is put, together with a due pro- portion of lead, into a shallow crucible, made of burned bones, called a cupel ; and the fusion of the metals is effected by exposing them to a considerable heat in a muffle, or small earthen oven, fixed in the midst of a furnace. The lead continually vitrifies, or becomes converted into a glassy calx, which dissolves all the imper- fect metals. This fluid glass, with its con- tents, soaks into the cupel, and leaves the precious metals in a state of purity. Du- ring the cupellation, the scoriae running down on all sides of the metallic mass, pro- duce an appearance called circulation ; by which the operator judges whether the process be going on well. When the metal is nearly pure, certain prismatic colours flash suddenly across the surface of the globule, which soon afterwards appears very brilliant and clean : this is called the brightening, and shows that the separa- tion is ended. After gold has passed the cupel, it may still contain either of the other perfect metals, platina, or silver. The former is seldom suspected ; the latter is separated by the operations called quartation and parting. Quartation consists in adding three parts of silver to the supposed gold, and fusing them together ; by which means the gold becomes at most one-fourth of the mass only. The intention of this is to separate the particles of gold from each other, so that they may not cover and de- fend the silver from the action of the nitric acid, which is to be used in the process of parting. Parting consists in exposing the mass, previously hammered or rolled out Yea. i. [24] thin, to the action of seven or eight times its weight of boiling nitric acid of a due strength. The first portion of nitric acid being poured off, about half the quantity, of a somewhat greater strength, is to be poured on the remaining gold ; and if it be supposed that this has not dissolved all the silver, it may even be repeated a second time. For the first operation an acid of the specific gravity of 1.280 may be used, diluted with an equal quantity of water; for the second, an acid about 1.26 maybe taken undiluted. If the acid be not too concentrated, it dissolves the sil- ver, and leaves the gold in a porous mass, of the original form ; but, if too strong, the gold is in a powdery form, which may be washed and dried. The weight of the original metal before cupellation, and in all the subsequent stages, serves to ascer- tain the degree of fineness of the ingot, or ore, of which it is a part. In estimating or expressing the fineness of gold, the whole mass spoken of is sup- posed to weigh twenty-four carats of twelve grains each, either real, or merely proportional, like the assayer's weights ; and the pure gold is called fine. Thus, if gold be said to be 23 carats fine, it is to be understood, that, in a mass weighing 24 carats, the quantity of pure gold amounts to 23 carats. In such small works as cannot be assay- ed by scraping off a part, and cupelling it, the assayers endeavour to ascertain its quality or fineness by the touch. This is a method of comparing the colour, and other properties of a minute portion of the metal, with those of small bars, the composition of which is known. These bars are called touch-needles; and they are rubbed upon the black basaltes, which, for this reason, is called the touchstone. Black flint or pottery will serve the same purpose. Sets of gold needles may con- sist of pure gold ; pure gold 23^ carats, with half a carat of silver ; 23 carats of gold, with one carat of silver ; 22^ carats of gold, with 1^ carats of silver ; and so on, till the silver amounts to four carats ; af- ter which the additions may proceed by whole carats. Other needles may be made in the same manner, with copper instead of silver ; and other sets may have the ad- dition consisting either of equal parts sil- ver and copper, or such proportions as the occasions of business require. The examination by the touch may be advan- tageously employed previous to quarta- tion, to indicate the quantity of silver ne- cessary to be added. In foreign countries, where trinkets and small work are required to be submitted to the assay of the touch, a variety of needles are necessary ; but they are not much used in England, They afford, how- ASS ASS jever, a degree of information, winch is more considerable than might at first be expected. The attentive assayer not only compares the colour of the stroke made upon the touchstone by the metal under examination, with that produced by his needle; but will likewise attend to the sensation of roughness, dr} ness, smooth- ness, or greasincss, which the texture of the rubbed incta] excites, when abraded by the stone. "When two strokes, perfect- ly alike in colour, are made if^on the stone, he may then wet them with aqua- fortis, which* will affect them very differ- ently, if they be not similar compositions ; or the stone itself may be made red-hot by the fire, or bv the blow-pipe, if thin black pottery be used ; in which case the phe- nomena of oxidation will differ, according to the nature and quantity of the alloy. The French government has from time to time caused various experimental in- quiries to be made respecting tbe art of assaying gold, which have thrown much light on this subject, and greatly tend to produce uniformity in the results of the operation. The latest report on this sub- ject may be seen in the Annales de Chi- mie, vol. vi. p. 64. ; which may be con- sulted for a full account of the experi- ments and history of former proceedings. The general result is as follows, nearly in the words of the authors : Six principal circumstances appear to affect the operation of parting: namely, the quantity of acid used in parting, or in the first boiling; the concentration of this acid ; the time employed in its applica- tion ; the quantity of acid made use of in the reprise, or second operation ; its con- centration ; and the time during which it is applied. From the experiments it has been shown, that each of these unfavour- able circumstances might easily occasion a loss of from the half of a thirty -second part of a carat, or two thirty-second parts. The writers explain their technical lan- guage by observing, that, the whole mass consisting of twenty-four carats, this thir- ty-second part denotes l-768th part of the mass. It may easily be conceived, there- fore, that if the whole six circumstances were to exist, and be productive of errors falling the same way, the loss would be very considerable. It is therefore indispensibly necessary, that one uniform process should be fol- lowed in the assays of gold ; and it is a matter of astonishment, that such an accu- rate process should not have been pre- scribed by Government for assayers in an operation of such great commercial im- portance, instead of every one being left to follow his own judgment. The pro- cess recommended in the report before us is as follows: Twelve grains of the gold intended ft* be assayed must be mixed with thirty grains- of fine silver, and cupelled with 108 grains^ of lead. The cupellation must be carefully attended to, and all the imperfect buttons rejected. When the cupellation is end- ed, the button must be reduced by lami- nation into a plate of 1 inch, or rather more, in length, and four or five lines in. breadth. This must be rolled up upon a quill, and placed in a matrass capable of holding about three ounces of liquid, when filled up to its narrow part. Two ounces and a half of very pure aquafortis, of the strength of 20 degrees of J3aume's areo- meter, must then be poured upon it; and the matrass being placed upon hot ashes or sand, the acid must be kept gently boil- ing for a quarter of an hour ; the acid must then be cautiously decanted and an additional quantity of 1| ounce, must be poured on the metal, and slightly boiled for twelve minutes. This being likewise carefully decanted, the small spiral piece of metal must be washed with filtered ri- ver water, or distilled water, by filling the matrass with this fluid. The vessel is then to be reversed, by applying the extremi- ty of its neck against the bottom of a cru- cible of fine earth, the internal surface of which is very smooth. The annealing must then be made, after having separated the portion of water which had fallen into the crucible ; and, lastly the annealed gold must be weighed. For the certainty of this operation, two assays must be made in the same manner, together with a third assay upon gold of twenty-four carats, ox' upon gold the fineness of which is perfect- ly and generally known. No conclusion must be drawn from this assay, unless the latter gold should prove to be of the fineness of twenty -four carats exactly, or of its known degree of fine- ness; for if there be either loss or surplus, it may be inferred that the other two as- says, having undergone the same opera- tion, must be subject to the same error. The operation being made according to this process, by several assayers, in cir- cumstances of importance, such as those which relate to large fabrications, the fine- ness of the gold must not be depended on, nor considered as accurately known, 1^ gross. Though these doses of sil- ver and lead appeared to be proper for all operations of assaying gold, the commissa- ries observe, nevertheless, that gold of a lower title than eighteen carats may be alloyed with two parts, and even less, of silver ; in oi'der that the small mass of me- tal, when it comes to be Iuminated,may not be too thin, so as to break in pieces during the parting. ATU ATI1 the assay ers have obtained a uni- form result, without communication with each other. The authors observe, however, that this identity must be considered as existing to the accuracy of half of the thirty -second part of a carat. For not- withstanding 1 every possible precaution or uniformity, it very seldom happens that an absolute agreement is obtained between the different assays of one and the same ingot, because the ingot itself may differ in its fineness in different parts of its mass. The assaying of silver does not differ 'from that of gold, excepting that the part- ing operation is not necessary. A cer- tain small portion of the silver is ab- sorbed by the cupel, and the more when a larger quantity of lead is used, un- less the quantity of lead be excessive ; in which case most of it will be scori- fied before it begins to act upon the silver. Messrs. Hellot, Tillet, and Mac- 3uer, from their experiments made by or- er of the French Government, have as- certained, that four parts of lead are re- quisite for silver of eleven pennyweights twelve grains fine, or containing this weight of pure silver, and twelve grains of alloy, in twelve pennyweights; six parts of lead for silver of eleven pen- cyweights ; eight parts of lead for silver of ten pennyweights ; ten parts of lead for silver of nine pennyweights; and soon in the same progression. ASTHIXGEXT PRINCIPLE. The effect called astringency, considered as distin- guishable by the taste, is incapable of be- ing defined. It is perceived in the husks of nuts, of walnuts, in green tea, and emi- nently in the nut-gall. This is probably owing to the circumstance, that acids have likewise the property of corrugating the fibres of the mouth and tongue, which is considered as characteristic of astringency as it relates to taste ; and hence the .gallic acid, which is commonly found united \viththe true astringent principle, was long mistaken for it. Seguin first distinguished them, and, from the use of this principle in tanning skins, has given it the name of tannin. Their characteristic differences are, the gallic acid forms a black precipi- tate with iron ; the astringent principle forms an insoluble compound with albu- men. See TANNIX. ATHAXOR. A kind of furnace, which has long since fallen into disuse. The very long and durable operations of the ancient chemists rendered it a desirable requisite, that their fires should be con- stantly supplied with fuel in proportion to the consumption. The athanor furnace was peculiarly adapted to this purpose. Beside the usual parts, it was provided with a hollow tower, into which charcoal was put. The upper part of the tower, when filled, was closely shut by a well- fitted cover; and the lower part commu- nicated with the fire -place of the furnace. In consequence of this disposition, the charcoal subsided into the fire-place gra- dually as the consumption made room for it; but that which was contained in the tower was defended from combustion by the exclusion of a proper supply of air. " * ATMOMETER. The name of an instru- ment contrived by Professor Leslie, to measure the quantity of exhalation from a humid surface in a given time. It con- sists of a thin ball of porous earthen-ware, two or three inches in diameter, with a small neck, to which is firmly cemented a long and rather wide tube of glass, bear- ing divisions, each of them corresponding 1 to an internal annular section, equal to a film of liquid that would cover the outer surface of the ball to the thickness of the thousandth part of an inch. These divi- sions are ascertained by a simple calcula- tion, and numbered downwards to the ex- tent of 100 or 200. To the top of the tube is fitted a brass cap, having a collar of lea- ther, and which, after the cavity has been filled with distilled or boiled water, is screwed tight. The outside of the ball being now wiped dry, the instrument is suspended out of doors, and exposed- -to the free action of the air. The quantity of evaporation from a wet ball is the same as from a circle having twice the diameter of the sphere. In the atmometer, the humidity transudes through the porous substance, just as fast as it evaporates from the external surface ; and this waste is measured by the corresponding descent of water in the stem. At the same time, the tightness of the collar taking off the pressure of the column of liquid, prevents it from oozing so profusely as to drop from the ball ; an inconvenience which, in the case of very feeble evaporation, might otherwise take place. As the process goes on, a corresponding portion of air is likewise imbibed by the moisture on the outside, and being introduced into the ball, rises in a small stream to replace the water. The rate of evaporation is nowise affected by the quality of the porous ball. It continues exactly the same when the exhaling surface appears almost dry, as when it glistens with superfluous mois- ture. When the consumption of water is excessive, it may be allowed to percolate by unscrewing the cap, taking care, how- ever, to let no drops fall.* Leslie on Heat and Moisture. ATMOSPHERE. See AIR (ATMOSPHERI- CAL). * ATOMIC THEORY. See EQUIVALENTS (CHEMICAL).* * ATROPIA. A new vegetable alkali, extracted by Dr. Brands 8 from the .iiropa ATT ATT belladonna, or deadly nightshade. It is white, brilliant, crystallizes in long nee- dles, is tasteless, and little soluble in wa- ter or alcohol. It resists a moderate heat. "With acids, it forms regular salts, and is capable of neutralizing a considerable pro- portion of acid. Sulphate of atropia is composed of, Sulphuric acid, 36.52 5.00 Atropia, 38.93 5.33 Water, 24.55 100.00.* ATTRACTION. The instances of attrac- tion which are exhibited by the phenome- na around us, are exceedingly numerous, and continually present themselves to our observation. The effect of gravity, which causes the weight of bodies, is so universal, that we can scarcely form an idea how the universe could subsist without it. Other attractions, such as those of magnetism and electricity, are likewise observable ; and every experiment in chemistry tends to show, that bodies are composed of va- rious principles or substances, which ad- here to each other with various degrees of force, and may be separated by known methods. It is a question among philo- sophers, whether all the attractions which obtain between bodies be referable to one general cause modified by circumstances ; or whether various original and distinct causes act upon the particles of bodies at one and the same time. The philosophers at the beginning of the present century were di-posed to consider the several at- tractions as essentially different, because the laws of their action differ from each other; but the moderns appear disposed to generalize this subject, and to consider all the attractions which exist between bodies, or at least those which are perma- nent, as depending upon one and the same cause, whatever it may be, which re- gulates at once the motions of the im- mense bodies that circulate through the celestial spaces, and those minute parti- cles that are transferred from one combi- nation to another in the operations of che- mistry. The earlier philosophers ob- served, for example, that the attraction of gravitation acts upon bodies with a force which is inversely as the squares of the distances ; and from mathematical deduc- tion they have inferred, that the law of at- traction between the particles themselves follows the same ratio; but when their observations were applied to bodies very near each other, or in contact, an adhesion took place, which is found to be much greater than could be deduced from that law applied to the centres of gravity. Hence they concluded, that the cohesive attraction is governed by a much higher ratio, and probably the cubes of the dis- tances. The moderns, on the contrary, among whom are Bergmann, Guyton-Mor- veau, and others, have remarked, that these deductions are too general, because, for the most part, drawn from the conside- ration of spherical bodies, which admit of no contact but such as is indefinitely small, and exert the same powers on each other, whichever side may be obverted. They remark, likewise, that the consequence depending on the sum of the attractions in bodies not spherical, and at minute distances from each other, will not follow the inverted ratio of the square of the dis- tance taken from any point assumed as the centre of gravity, admitting the parti- cles to be governed by that law ; but that it will greatly differ, according to the sides of the solid which are presented to each other, and their respective distances ; in- somuch that the attractions of certain par- ticles indefinitely near each other will be indefinitely increased, though the ratio of the powers acting upon the remoter parti- cles may continue nearly the same. This doctrine, which however requires to be much more strictly examined by the application of mathematical principles, obviously points to a variety of interesting consequences. The polarity of particles, or their disposition to present themselves in their approach to each other in certain aspects, though it has been treated as a chimerical notion by a few writers, is one of the first of these results. These are speculations, which, with re- gard to the present state of chemistry, stand in much the same situation as the theory of gravity, which is minutely de- scribed in Plutarch, did with regard to as- tronomy before the time of Newton. As the celestial phenomena were formerly ar- ranged from observation merely, but are now computed from the physical cause, gravitation; so, at present, chemistry is the science of matter of fact duly arranged, without the assistance of any extensive theory immediately deduced from the fi- gures, volumes, densities, or mutual ac- tions of the particles of bodies. What it may hereafter be, must depend on the ability and research of future chemists; but at present we must dismiss this remo- ter part of theory, to attend more imme- diately to the facts. That the parts of bodies do attract each other, is evident from that adhesion which produces solidity, and requires a certain force to overcome it. For the sake of per- spicuity, the various effects of attraction have been considered as different kinds of affinity or powers. That power which physical writers call the attraction of co- hesion, is generally called the attraction of aggregation by chemists. Aggregation is considered as the adhesion of parts of ATT ATT th same kind. Thus a number of pieces of brimstone united by fusion, form an ag- gregate, the parts of which may be sepa- rated again by mechanical means. These parts have been called integrant parts ; that is to say, the minutest parts into which a body can be divided, either really or by the imagination, so as not to change its nature, are called integrant parts. Thus, if sulphur and an alkali be combined together, and form liver of sulphur, we may conceive the mass to be divided and subdivided to an extreme degree, until at length the mass consists of merely a par- ticle of brimstone and a paricle of alkali. This then is an integrant part ; and if it be divided further, the effect which chemists call decomposition will take place; and the particles consisting no longer of liver of sulphur, but of sulphur alone, and al- kali alone, will be what chemists call com- ponent parts or principles. The union of bodies in a gross way is called mixture. Thus sand and an alkali may be mixed together. But when the very minute parts of a body unite with those of another so intimately as to form a body, which has properties different from those of either of them, the union is called combination, or composition. Thus, if sand and an alkali be exposed to a strong heat, the minute parts of the mixture com- bine, and form glass. The earlier chemists were very desirous of ascertaining the first principles, or ele- ments of bodies ; and they distinguished by this name such substances as their art was incapable of rendering more simple. They seem however to have overlooked the obvious circumstance, that the limits of art are not the limits of nature. At pre- sent we hear little concerning elements. Those substances which we have not hitherto been able to analyze, or which, if decomposed, have hitherto eluded the ob- servation of chemists, are indeed con- sidered as simple substances relative to the present state of our knowledge, but in no other respect ; for a variety of ex- periments give us reason to hope, that future enquiries may elucidate their na- ture and composition. Some writers, cal- ling these simple substances by the name of Primary Principles, have distinguished compounds of these by the name of Se- condary Principles, which they suppose to enter again into combinations without decomposition or change. It must be confessed, nevertheless, that no means have yet been devised to show whether any such subordination of principles ex- ists. We may indeed discover that a com- pound body consists of three or more prin- ciples; but whether two of these be pre- viously united, so as to form a simple sub- stance with relation to the third, or what in other respects may be their arrange- ment, we do not know. That it does ex- ist, however, seems clear by making com- binations in varied orders. Thus a weak solution of alkali will not dissolve oil ; but a combination of oil and alkali will not separate by the addition of water. The alkali therefore adheres to that with which it was first combined. See also the article VEGETABLES. If two solid bodies, disposed to combine together, be brought into contact with each other, the particles which touch will combine, and form a compound ; and if the temperature at which this new com- pound assumes the fluid form be higher than the temperature of the experiment, the process will go no further, because this new compound being interposed be- tween the two bodies, will prevent their further access to each other ; but if, on the contrary, the freezing point of the compound be lower than this temperature, liquefaction will ensue ; and the fluid par- ticles being at liberty to arrange them- selves according to the law of their at- tractions, the process will go on, and the whole mass will gradually be converted into a new compound in the fluid state. An instance of this may be exhibited by mixing common salt and perfectly dry pounded ice together. The crystals of the salt alone will not liquefy unless very much heated ; the crystals of the water, that is to say, the ice, will not liquefy un- less heated as high as thirty-two degrees of Fahrenheit ; and we have of course supposed the temperature of the experi- ment to be lower than this, because our water is in the solid state. Now it is a well known fact, that brine, or the satu- rated solution of sea salt in water, cannot be frozen unless it be cooled thirty-eight degrees lower than the freezing point of pure water. It follows then, that, if the temperature of the experiment be higher than this, the first combinations of salt and ice will produce a fluid brine, and the combination will proceed until the tem- perature of the mass has gradually sunk as low as the freezing point of brine ; af- ter which it would cease, if it were not that surrounding bodies continually tend to raise, the temperature. And according- ly it is found by experiment, that, if the ice and the salt be previously cooled be- low the temperature of freezing brine, the combination and liquefaction will not take place. See CALORIC. The instances in which solid bodies thus combine together not being very nume- rous, and the fluidity which ensues imme- diately after the commencement of this kind of experiment, have induced several chemists to consider fluidity in one or both of the bodies applied to each other, ATT ATT to be a necessary circumstance, in order that they may produce chemical action upon each other. Corpora non agunt nisi sint fluida. If one of two bodies applied to each other be fluid at the temperature of the experiment, its parts will successively unite with the parts of the solid, which will by that means be suspended in the fluid, and disappear. Such a fluid is called a solvent or menstruum; and the solid body is said to be dissolved. Some substances unite tog-ether in all proportions. In this way the acids unite vith water. But there are likewise many substances which cannot be dissolved in a fluid, at a settled temperature, in any quantity .beyond a certain proportion. Thus, water will dissolve only about one- third of its weight of common salt ; and if more salt be added, it will remain so- lid. A fluid which holds in solution as much of any substance as it can dissolve, is said to be saturated with it. But satu- ration with one substance is so far from preventing 1 a fluid from dissolving another body, that it very frequently happens, that the solvent power of the compound exceeds that of the original fluid itself. Chemists likewise use the word saturation in another sense ; in which it denotes, such a union of two bodies as produces a compound the most remote in its proper- ties from the properties of the component parts themselves. In combinations wkere one of the principles predominates, the one is said to be supersaturated, and the other principle is said to be subsaturated. Heat in general increases the solvent power of fluids, probably by preventing 1 part of the dissolved substance from con- gealing, or assuming the solid form. It often happens, that bodies which have no tendency to unite are made to combine together by means of a third, which is then called the medium. Thus, water and fat oils are made to unite by the medium of an alkali, in the combination called soap. Some writers, who seem desirous of multiplying terms, call this tendency to unite the affinity of intermedium. This case has likewise been called disposing affinity ; but Berthollet more properly styles it re- ciprocal affinity. He likewise distinguish- es affinity into elementary, when it is be- tween the elementary parts of bodies ; and resulting, when it is to a compound only, and would not take place with the elements of that compound. It very frequently happens, on the con- trary, that the tendency of two bodies to unite, or remain in combination together, is weakened or destroved by the addition of a third. Thus, alcohol unites with wa- ter in such a manner as to separate most salts from it. A striking 1 instance of this is seen in a saturated or strong solution of nitre in water, if to this there be added an equal measure of alcohol, the greater part of the nitre instantly falls down. Thus magnesia is separated from a solu- tion of Epsom salt, by the addition of an alkali, which combines with the sulphuric acid, and separates the earth. The prin- ciple which falls down is said to be pre- cipitated, and in many instances is called a precipitate. Some modern chemists use the term precipitation in a more extended, and rather forced sense; for they apply it to all substances thus separated. In this enunciation, therefore, they would say, that potash precipitates soda from a solu- tion of common salt, though no visible separation or precipitation takes place ; for the soda, when disengaged from its acid, is still suspended in the water by reason of its solubility. From a great number of facts of this na- ture, it is clearly ascertained, not as a pro- bable hypothesis, but as simple matter of fact, that some bodies have a stronger ten- dency to unite than others ; and that the union of any substance with another will exclude, or separate, a third substance, which might have been previously united with one of them ; excepting only in those cases wherein the new compound has a tendency to unite with that third sub- stance, and form a triple compound. Tins preference of uniting, which a given sub- stance is found to exhibit with regard to other bodies, is by an easy metaphor call- ed elective attraction, and is subject to a variety of cases, according to the number and the powers of the principles which are respectively presented to each other. The cases which have been most frequently observed by chemists, are those called sim- ple elective attractions, and double elec- tive attractions. When a simple substance is presented or applied to another substance compoun- ded of two principles, and unites with one of these two principles so as to separate or exclude the other, this effect is said to be produced by simple elective attrac- tion. It may be doubted whether any of our operations have been carried to this de- gree of simplicity. All the chemical prin- ciples we are acquainted with are simple only with respect to our power of decom- posing them ; and the daily discoveries of our contemporaries tend to decompose those substances, which chemists a few years ago considered as simple. Without insisting, however, upon this difficulty, we may observe, that water is concerned in all the operations which are called humid, and beyond a doubt modifies all the effects of such bodies as are suspended in it; and the variationsk of temperature, whether ATT AIT arising from an actual igneous fluid, or from a mere modification of the parts of bodies, also tend greatly to disturb the ef- fects of elective attraction. These causes render it difficult to point out an example of simple elective attraction, which may in strictness be reckoned as such. Double elective attraction takes place when two bodies, each consisting of two principles, are presented to each other, and mutually exchange a principle of each ; by which means two new bodies, or com- pounds, are produced, of a different na- ture from the original compounds. Under the same limitations as were pointed out in speaking of simple elective attraction, we may offer instances of dou- ble elective attraction. Let oxide of mer- cury be dissolved to saturation in the ni- tric acid, the water will then contain ni- trate of mercury. Again, let potash be dissolved to saturation in the sulphuric acid, and the result will be a solution of sulphate of potash. If mercury were ad- ded to the latter solution, it would indeed tend to unite with the acid, but would pro- duce no decomposition ; because the elec- tive attraction of the acid to the alkali is the strongest. So likewise, if the nitric acid alone be added to it, its tendency to unite with the alkali, strong as it is, will not effect any change, because the alkali is already in combination with a stronger acid. But if the nitrate of mercury be added to the solution of sulphate of pot- ash, a change of principles will take place, the sulphuric acid will quit the alkali, and unite with the mercury, while the nitric acid combines with the alkali ; and these two new salts, namely, nitrate of potash, and sulphate of mercury, may be obtained separately by crystallization. The most remarkable circumstance in this process is, that the joint effects of the attractions of the sulphuric acid to mercu- ry, and the nitric acid to alkali, prove to be stronger than the sum of the attractions between the sulphuric acid and the alkali, and between the nitrous acid and the mer- cury ; for, if the sum of these two last had not been weaker, the original combinations would not have been broken, f f The influence of insolubility and of gravity is here too much overlooked. It is a general law, that when compounds are mixed, new combinations will take place between those substances, which, when united, are most insoluble. The mercury is of itself perfectly insoluble, and it is many times heavier than potash or nitric acid. The sulphuric acid is much heavier than the nitric, and forms with mercury an insoluble salt. Hence the superior affinity of the nitric acid and potash to water, as well as gravitation, tends to pre- cipitate the sulphate of mercury. Mr. KIrwan, who first, in the year 1782, considered this subject with that attention, it deserves, called the affinities which tend to preserve the original combinations, the quiescent affinities. He distinguished the affinities or attractions, which tend to pro- duce a change of principles, by the name of the divellent affinities. Some eminent chemists are disposed to consider as effects of double affinities, those changes of principles only, which would not have taken place without the assistance of a fourth principle. Thus, the mutual decomposition of sulphate of soda and nitrate of potash, in which the alkalis are changed, and sulphate of potash and nitrate of soda are produced, is not considered by them as an instance of dou- ble decomposition ; because the nitre would have been decomposed by simple elective attraction, upon the addition of the acid only. There are various circumstances which modify the effects of elective attraction, and have from time to time misled che- mists in their deductions. The chief of these is the temperature, which, acting differently upon the several parts of com- pounded bodies, seldom fails to alter, and frequently reverses the effects of the af- finities. Thus, if alcohol be added to a solution of nitrate of potash, it unites with the water, and precipitates the salt at a common temperature. But if the tempe- rature be raised, the alcohol rises on ac- count of its volatility, and the salt is again dissolved. Thus again, if sulphuric acid be added, in a common temperature, to a combination of phosphoric acid and lime, it will decompose the salt, and disengage the phosphoric acid ; but if this same mix- ture of these principles be exposed to a considerable heat, the sulphuric acid will have its attraction to the lime so much di- minished, that it will rise, and give place again to the phosphoric, which will com- bine with the lime. Again, mercury kept in a degree of heat very nearly equal to volatilizing it will absorb oxygen, and be- come converted into the red oxide for- merly called precipitate per se , but if the heat be augmented still more, the oxygen will assume the elastic state, and fly off, leaving the mercury in its original state. Numberless instances of the like nature continually present themselves to the ob- servation of chemists, which are sufficient to establish the conclusion, that the elec- tive attractions are not constant but at one and the same temperature. Many philosophers are of opinion, that the variations produced by change of tem- perature arise from the elective attraction of the matter of heat itself. But there are no decisive experiments either in con- firmation or refutation of this hypothesis. If we except the operation of heat, ATT ATT which really produces a change in the elective attractions, we shall find, that most of the other difficulties attending this subject arise from the imperfect state of chemical science. If to a compound of two principles a third be aclclecl, the effect of this must necessarily be different ac- cording to its quantity, and likewise ac- cording to the state of saturation of the two principles of the compounded body. If the third principle which is added be in excess, it may dissolve and suspend the compound which may be newly lormed, and likewise that which might have been precipitated. The metallic solutions, de- composed by the addition of an alkali, af- ford no precipitate in various cases when the alkali is in excess ; because this ex- cess dissolves the precipitate, which would else have fallen down. If, on the other hand, one of the two principles of the compound body be in excess, the addition of a third substance may combine with that excess, and leave a neutral substance, ex- hibiting very different properties from the former. Thus, if cream oi tartar, which is a salt of difficult solubility, consisting of potash united to an excess of the acid of tartar, be dissolved in water, and chalk be added, the excess unites with part of the lime of the chalk, and forms a scarcely so- luble salt; and the neutral compound, which remains after the privation of this excess of acid, is a very soluble salt, great- ly differing in taste and properties from the cream of tartar. The metals and the acids likewise afford various phenomena, according to their degree of oxidation. A determinate oxidation is in general neces- sary for the solution of metals in acids ; and the acids themselves act very differ- ently, accordingly as they are more or less acidified. Thus, the nitrous acid gives place to acids which are weaker than the nitric acid : the sulphurous acid gives place to acids greatly inferior in attractive power or affinity to the sulphuric acid. The deception arising from effects of this na- ture is in a great measure produced by the want of discrimination on the part of chemical philosophers ; it being evident, that the properties of any compound sub- stance depend as much upon the propor- tion of its ingredients, as upon their re- spective nature. The presence and quantity of water is probably of more consequence than is yet supposed. Thus, bismuth is dissolved in nitrous acid, but falls when the water is much in quantity. The same is true of antimony. Hibaucout has shown the last (Annales de Chimie, TV. 122.) in alum, and it is likely that the fact is more com- mon than is suspected. Whether the at- traction and strength, as to quantity in saturation, be not variable by the presence or absence of water, must be referred to experiment. The power of double elective attrac- tions too, is disturbed by this circumstance. If muriate of lime be added to a solution of carbonate of soda, they are both decom- posed, and the results are muriate of soda and carbonate of lime. But if lime and muriate of soda be mixed with just water sufficient to make them into a paste, and this be exposed to the action of carbonic acid gas, a saline efflorescence consisting of carbonate of soda will be formed on the surface, and the bottom of the vessel will be occupied by muriate of lime in a state of deliquescence. M. Berthollet made a great number of experiments, from which he deduced the following law : that in elective attrac- tions the power exerted is not in the ratio of the affinity simply, but in a ratio com- pounded of the force of affinity and the quantity of the agent; so that quantity may compensate for weaker affinity. Thus an acid which has, a weaker affinity than another for a given base, if it be employed in a certain quantity, is capable of taking part of that base from the acid which has a stronger affinity for it ; so that the base will be divided between them in the com- pound ratio of their affinity and quantity. This division of one substance between two others, for which it has different af- finities, always takes place, according to him, when three such are present under circumstances in which they can mutually act on each other. And hence it is, that the force of affinity acts most powerfully, when two sub -tances- first come into con- tact, and continues to decrease in power as either approaches the point of satura- tion. For the same reason it is so diffi- cult to separate the last portions of any substance adhering to another. Hence, if the doctrine laid down by M. Berthollet be true, to its utmost extent, it must be impossible ever to free a compound com- pletely from any one of its constituent parts by the agency of elective attraction ; so that all our best established analyses are more or less inaccurate. The solubility or insolubility of princi- ples, at the temperature of any experi- ment, has likewise tended to mislead chemists, who have deduced consequen- ces from the first effects of their experi- ments. It is evident, that many separations may ensue without precipitation ; because this circumstance does not take place un- less the separated principle be insoluble, or nearly so. The soda cannot be preci- pitated from a solution of sulphate of soda, by the addition of potash, because of its great solubility ; but, on the contrary, the new compound itself, or sulphate of pot- ash, which is much less soluble, may fall ATT ATT down, if there be not enough water pre- sent to suspend it. No certain knowledge ean therefore be derived from the appear- ance or the want of precipitation, unless the products be carefully examined. In some instances all the products remain suspended, and in others they all fall down, as may be instanced in the decom- position of sulphate of iron by lime. Here the acid unites with the lime, and forms sulphate of lime, which is scarcely at all soluble ; and the still less soluble oxide of iron, which was disengaged, falls down along with it. Many instances present themselves, in which decomposition does not take place, but a sort of equilibrium of affinity is per- ceived. Thus, soda, added to the super- tartrate of potash, forms a triple salt by ombining with its excess of acid. So likewise ammonia combines with a por- tion of the acid of muriate of mercury, and forms the triple compound formerly distinguished by the barbarous name of sal ale mb roth. When we reflect maturely upon all the circumstances enumerated, or slightly touched upon, in the foregoing pages, we may form some idea of the extensive field of research, which yet remains to be ex plored by chemists. If it were possible to procure simple substances, and combine two together, and to this combination of two to add one more of the other simple substances, the result of the experiment would in many cases determine, by the exclusion of one of the three, that its af- finity to either of the remaining- two was less than that between those two respec- tively. In this way it would be ascertain- ed, in the progress of experimental in- quiry, that the simple attractions of a se- ries of substances were gradually increas- ing or diminishing in strength. Thus, am- monia separates alumina from the sulphu- ric acid ; magnesia, in like manner, sepa- rates the ammonia ; lime predominates, in the strength of affinity, over magnesia, as appears by its separating this last earth ; the soda separates the lime, and itself gives place to the potash ; and, lastly, potash yields its acid to barytes. The sim- ple elective attractions of these several substances to sulphuric acid, are therefore in the inverted order of their effects: barytes is the strongest ; and this is suc- ceeded regularly by potash, soda, lime, magnesia, ammonia, and alumina. It is evi- dent, that results of this nature, being tabulated, as was first done by the cele- brated Geoffroy, and afterwards by Berg- Tnann, must afford a valuable mass of che- mical knowledge. It must be remarked, however, that these results merely indi- cfate, that the powers are greater or less than each other ; but how much greater or less is not determined, either absolute- Vou. i, {25} ly or relatively. Tables of this nature can- not therefore inform us of the etiects which may take place in the way of dou- ble affinity, for want of the numerical re- lations between the attracting powers. Thus, when we are in possession of the. order of the simple elective attractions between the sulphuric acid and a series of substances, and also between the nitrous acid and the same substances; and when, in addition to this, the respective powers of each of the acids upon every one of the substances singly taken, are known, so far as to determine which will displace the other ; yet we cannot thence foretell the result of applying two combinations to each other, each containing an acid united with one of the number of simple substan- ces. Or, more concisely, a table of simple elective attractions can be of no use to determine the effects of double elective attraction, unless the absolute power of the attractions be expressed by number instead of their order merely. * It has been often remarked, that the action of a substance is diminished in pro- portion as it approaches to a state of satu- ration ; and this diminution of power has been employed to explain several chemi- cal|f)henomena. It is likewise known, that the resistance found in expelling a sub- stance from the last portions of a combi- nation, either by affinity or heat, is much greater than at the commencement of the decomposition, and sometimes such, that its entire decomposition cannot be effec- ted. Thus the black oxide of manganese exposed to heat will part with only a cer- tain definite quantity of its oxygen. No degree of heat can expel the whole. According to Berthollet, when two sub- stances are in competition to combine with a third, each of them obtains a de- gree of saturation proportionate to its af- finity multiplied by its quantity, a product, which he denominates mass. The subject of the combination divides its action in proportion to the masses, and by varying the latter, this illustrious chemist thinks, that the results also will be varied. The following are the forces which he regards as exercising a great influence upon che- mical combinations and phenomena, by concurring with or opposing the mutual affinity of the substances brought into ac - tion. 1. The action of solvents, or the af- finity which they exert according to their proportion. Thus, if into a very dilute so- lution of muriate of lime, a solution of sul- phate of soda be poured, no precipitate of sulphate of lime will happen, though the quantity of the solvent water be lesjs than is necessary to dissolve the calcare* ous sulphate. If the same two saline solu^ tions be mixed with less water, the sul- phate of lime will fall in a few seconds, or a few minutes, according to ATT ATT of the mingled solutions. 2. The force of cohesion, which is the effect of the mutu- al affinity of the particles of a substance or combination. Hence we can easily see why a solution of pure potash, which so readily dissolves pulverulent alumina, has no effect on alumina concreted and con- densed in the oriental gems. The lowest red heat kindles charcoal, or determines its combination with atmospherical oxy- gen ; but a much higher temperature is requisite to burn the same carbonaceous matter, more densely aggregated in the diamond. 3. Elasticity, whether natural or produced by heat; which has,by some,been considered as the affinity of caloric, (f 1) Of the influence of this power a fine illus- tration is afforded by muriate of lime and carbonate of ammonia. When a solution of the latter salt is poured into one of the former, a double decomposition instantly takes place : carbonate of lime falls to the bottom in powder, and muriate of ammo- nia floats above. Let this liquid mixture be boiled for some time ; exhalation of ammoniacal gas will be perceived by the nostrils, and the carbonate of lime will be redissolved ; as may be proved by the fur- ther addition of carbonate of ammonia, (f 2) This will cause an earthy precipitate^rom the liquid, which prior to ebullition was merely muriate of ammonia. 4. Efflores- cence, a power which acts only under very rare circumstances. It is exemplified in the natron lakes of Egypt ; on the mar- gin of which, according to Berthollet, car- bonate of lime decomposes muriate of so- da, in consequence of the efflorescing property of the resulting carbonate. 5. Gravity likewise exerts its influence, par- ticularly when it produces the compres- sion of elastic fluids; but it may always without inconvenience be confounded with the force of cohesion. M. Berthollet thinks, that as the tables of affinity have all been constructed upon the supposition, that substances possess different degrees of affinity, which pro- (fl) This is obscure. Elasticity, as an an- tagonist of chemical affinity, seems always to result from calorific repulsion. Par- ticles evidently arrange themselves of choice in certain angles, from which they may be made to deviate, to a certain ex- tent, in obedience to exterior force ; and yet they regain their figure, as soon as unconstrained. Perhaps this is what the author means by natural elasticity. For " affinity of caloric" we ought probably to read effects of caloric. (|2) It is not the carbonate of lime, but the lime of the carbonate, that is redissolv- ed. I question if the " exhalation" be not carbonate of ammonia, instead of ammonia- cal gas* duce the decompositions and combinations that are formed, independently of the pro- portions and other conditions which con- tribute to the results ; these tables are cal- culated only to give a false idea of the de- grees of chemical action of the substances arranged in them. " The denomination of elective affinity," says he, " is in itself erroneous, since it supposes the union of one entire substance with another, in pre- ference to a third, while there is only a division of action, subject to other chemi- cal conditions." The force of cohesion, which was formerly considered merely as an obstacle to solution, limits not only the quantities of substances which may be brought into action in a liquid, and conse- quently modifies the conditions of the sa- turation which follows ; but it is the pow- er which causes the precipitations and crystallizations that take place, and deter- mines the proportions of such combina- tions as are made by quitting the liquid ; it is this force which sometimes even pro- duces the separation of a substance, with- out its forming any combination -with another substance, as has been remarked in metallic precipitations. Elasticity acts by producing effects opposite to those of cohesion, and which consists either in withdrawing some substances from the ac- tion of others in a liquid, or in diminishing the proportion which exists within the sphere of activity; but when all the sub- stances are in the elastic state, their ac- tion is subjected to the same conditions. If tables were formed which would repre- sent the disposition to insolubility or vo- latility, in the different combinations, they would serve to explain a great number of combinations which take their origin from the mixture of different substances, and from the influence of heat. These con- siderations need not prevent us, says Berthollet, from using the term affinity to denote the whole chemical power of a body exerted in a given situation, even by its present constitution, its proportion, or even by the concurrence of other affini- ties ; but we must avoid considering this power as a constant force, which produces compositions and decompositions. All substances, according to him, exert a mu- tual action during the time they are in the liquid state ; so that in a solution, for example, of sulphate of potash and muri- ate of soda, these two salts are not distinct, while there is no cause to determine the separation from their combination; but there exists in this liquid, sulphuric acid, muriatic acid, soda, and potash. In like manner, when the proper quantity of car- bonate of potash is added to muriate of soda, the mingled solution does not con- sist of carbonate of soda and muriate of potash, resulting from complex affinity, but contains simply muriatic and carbonic ATT ATT acids with potash and soda, in quadruple union and saturation. It is the crystalli- zing property of the soda carbonate, which, after due evaporation, determines the definite decomposition, and not any power of elective attraction. Or gene- rally, when one substance separates from a combination by the introduction of an- other, it is not merely from being- sup- planted by the superior affinity of an an- tagonist, but because its intrinsic tenden- cy to the solid or gaseous form educes it from its former associate. There is cer- tainly much truth in the proposition of Berthollet. But with regard to the indefinite parti- tion of a base between two rival acids, and of an acid between two rival bases, a doctrine which that profound philosopher laboured to establish by a wide experi- mental induction, many facts of an irre- concileable nature occur. Sir II. Davy has remarked with his usual good judg- ment, that were this proposition correct, it is evident that there could be scarcely any definite proportions ; a salt crystalli- zing in a strong alkaline solution would be strongly alkaline ; in a weak one less alkaline ; while in an acid solution it would be acid. But this does not seem to be the case. In combinations of gaseous bodies, whose constitution gives their par- ticles perfect freedom of motion, the pro- portions are definite and unchangeable, however we may change the proportions of the aeriform mixture. And in all solid compounds that have been accurately ex- amined, in which there is no chance of mechanical mixture, the same law seems to prevail. Different bodies may indeed be dissolved in different menstrua in very various proportions, but the result maybe regarded as a mixture of different solu- tions, rather than a combination. With regard to glasses and metallic alloys, ad- duced by Berthollet, it is sufficient to know that the points of fusion of alkali, glass, and oxides of lead and tin, are so near each other, that transparent mixtures of them may be formed. The attractive power of matter is undoubtedly general, but in the formation of aggregates, cer- tain definite arrangements take place. Bergmann observed long ago, that when nitric acid was digested on sulphate of potash, a portion of nitre was formed, in apparent contradiction to the superior af- finity which he had assigned to sulphuric acid for the potash. But he also gave what appears to be a satisfactory explana- tion of this seeming anomaly, which Ber- thollet has adduced in support of his views of indefinite and universal partition. Sulphuric acid tends to combine in two distinct but definite proportions with pot- ash, forming the neutral sulphate and the bisulphate, Nitric acid may therefore ab- stract from the neutral salt, that portio.n of potash which it should lose to pass into the acidulous salt; but it will not deprive it of any more. Hence this very example is decidedly adverse to the indefinite combinations and successive partitions taught by Berthollet. The above decom- position resolves itself evidently, there- fore, into a case of double affinity. That a large quantity of pure potash can separate a little sulphuric acid from the sulphate of barytes, has been stated by Berthollet ; but it is a circumstance difficult to demon- strate. If the operation be conducted with access of air, then carbonate of pot- ash is readily formed, and a well known double affinity comes into play, viz. that of barytes for carbonic acid on one hand, and of sulphuric acid for potash on the other. Supposing the agency of carbon- ic acid to be excluded, then are we to believe that the potash having become a soluble sulphate, exists in liquid union with pure barytes ? See M. Dulong's ex- periments further on. When M. Berthollet separated a little potash from sulphuric acid by soda, he merely formed a little bisulphate of pot- ash, while the free potash united to the water and alcohol, for which it has a strong affinity, and sulphate of soda was also formed. This, therefore, is a very in- telligible case of compound attraction. According to M. Berthollet, whenever an earth is precipitated from a saline com- bination, by an alkali, it should carry down with it a portion of its acid associate. But sulphate of magnesia acted on by potash, yields an earthy precipitate, which, after proper washing, betrays the presence of no retained sulphuric acid. The neutral salts of soda and potash part with none of their acid to magnesia, by the longest digestion in their solutions. If on the tartrate of lime, or oxalate of lead, the portion of sulphuric acid adequate to saturate these respective bases be poured, entire decomposition will be effected without any partition whatever. Now, sulphate of lime, which is the result in the first case, being actually a much more soluble salt than the tartrate, we should expect a portion of the latter to resist de- composition by the aid of its cohesive force. A plate of iron plunged into a so- lution of sulphate of copper, separates the whole of the latter metal. An equally absolute decomposition is effected by zinc on the saline solutions of lead and tin. The sum total of oxygen and acid is here transferred to the decomposing body, without any partition whatever. We have already observed, that sul- phate of barytes digested in a hot solution of carbonate of potash, gives birth to a portion of carbonate of barytes and sul- phate of potash. But by M. Dulong's ex- ATT ATT periment, the reverse decomposition is possible, viz. carbonate of barytes being- digested in solution of sulphate of potash, we obtain sulphate of barytes and carbo- nate of potash. Are we hence to infer, that Sulphate of barytes and carbonate of potash having- for some time amused the operator by the production of an alkaline sulphate and earthy carbonate, will change their mood, and retracing- their steps, restore things to their pristine condition ; and thus in alternate oscillation for ever ? If chlorine gas be made to act on the oxides of mercury, tin, or antimony, it will unite to the metallic base, and dis- place every particle of the oxygen. Now, the resulting chlorides cannot owe their purity to any superiority of cohesive force which they possess over the oxides, which, on the contrary, are both denser and more fixed than the new compounds. Finally, if 25 parts of pure magnesia mix- ed with 35.6 of dry lime, be digested in 85 parts of nitric acid, sp. gr. 1.500, dilu- ted with water, we shall find that the whole lime will be dissolved, but not a particle of the magnesia. On decanting the neutral calca-eous nitrate, washing and drying the earthy residuum, we shall procure the 25 parts of magnesia un- changed. We are, therefore, entitled to affirm, that affinity is elective, acting in the dif- ferent chemical bodies with gradations of attractive force, liable however to be modified, as we have shown in the case of muriate of lime and carbonate of ammo- nia, by temperature, and other adventi- tious powers. Decompositions which cannot be pro- duced by single attractions, may be effect- ed by double affinity ; and that, we may expect with the greater certainty, a pri- ori, if one of the two resulting compounds of the double interchange, naturally ex- ists in the solid or aeriform state. And if the one resulting compound be solid and the other gaseous, then decomposition will be certain and complete. This ap- plies with equal force to single affinities, or decompositions. Thus when sulphuric acid and muriate of lime in due propor- tions are exposed to heat, a perfect de- composition is accomplished, and pure sulphate of lime and muriatic acid gas are produced. But when the various mixed ingredients remain in solution, it is then reasonable to think with Berthollet, that a reciprocal attraction pervades the whole, modifying its nature and properties. Thus solution of sulphate of copper is blue, that of muriate of copper is green. Now, if into a solution of the former salt, we pour muriatic acid, we shall observe this robbing the sulphuric acid of a quantity of the cupreous oxide, proportional to its mass; for the more muriatic acid we add, the greener will the liquid become. But if, by concentration, the sulphate of cop- per be suffered to crystallize, the pheno- mena change ; a new force, that ot crv stal- lization, is superaclded, which aids the af- finity of the sulphuric acid, and decides the decomposition. The surplus of each of these acids is employed in counterba- lancing the surplus of its antagonist, and need not be considered as combined with the copper. Here, however, we verge on the obscure and unproductive domain of chemical metaphysics, a region in which a late respectable systematist delighted to expatiate. M. Bethollet estimates the attractive forces or affinities of bodies of the same class, to be inversely as their saturating quantities. Thus, among acids, 50 parts of real sulphuric, will saturate as much potash or soda as 67 of real nitric, and as 27 TJ of carbonic. Thus too, 21i of ammo- nia will saturate as much acid as 25 of magnesia, 35 A of lime, and 59 of potash. Hence he infers 'hat the carbonic acid is endowed with a higher affinity ihan the sulphuric ; and this, than the nitric. The same proposition applies to ammonia, magnesia, lime and potash. But in direct hostility to this doctrine, we have seen lime exercise a greater affinity for the acids than magnesia. And though M. Berthollet has ingeniously sought to ex- plain away the difficulty about potash, am- monia, and carbonic acid, by referring to the solid or gaseous results of their action ; yet it is hard to conceive of solidity opera- ting in producing an effect, before solidity exists, and of elasticity opera ing while the substance is solid or liquid. On this point a good syllogism has been offered by SirH. Davy. "The action," says this profound chemist, "between the consti- tuents of a compound must be mutual. Sulphuric acid, there is every reason to believe, has as much attraction for barytes, as barytes has for sulphuric acid, and ba- rytes is the alkaline substance of which the largest quantity is required to satu- rate sulphuric acid; therefore, on M. Ber- thollet's view, it has the weakest affinity for that acid ; but less sulphuric acid satu- rates this substance than any other earthy or alkaline body. Therefore, according to M. Berthollet, sulphuric acid has a stronger affinity for barytes than for any other substance ; which is contradictory." In the table of chemical equivalents at the end of the Dictionary, will be found a view of the definite proportions in which the various chemical bodies com- bine, referred to their primary or lowest numerical terms, vulgarly called the \veigJits of the atoms. Mr. Higgins, the real author of the Atomic Theory, in first promulgating its principles in his Comparative View of tl*e ATT ATT Phlogistic and Antiphlogistic Hypotheses, connected their exposition with general views of the relative forces of affinity among the combining particles. These forces he illustrates by diagrams, to which I have adverted, in the article EQ.UIVA- XENTS (CHEMICAL). This joint considera- tion of combining/97'ce 1 and combining ra- tio, .:as been neglected by subsequent wri- ters , A hence, Mr. Higg'ins says, " The atomic doctrine has been applied by me in abtruse and difficult researches. Its ap- plet, jn by Mr. Dalton, has been in a ge nerui and popular way; andii is from these circumstances alone, that it gained the name of Daltcn's Theory." Since the chemical statics appeared, perhaps no chemist has contributed so jnany important facts to the docrrines of affinity as M. Dulong. His admirable in- quiries concerning the mutual decompo- sition of soluble and insoluble salts, were presented to the National Institute, and afterwards published in the Annales de Chimie, torn. 82 ; from which they were translated into the -5th and 36th volumes of Nicholson's Journal, and an abstract of them was given in the 41st vol. of the Phil. Mag. Notwithstanding such means of notoriety, it is amusing to observe so unwearied a compiler as Dr. Thomson, recently appropriating to his friend Mr. Phillips, the discovery of a fact observed and recorded years before by M. Dulong; and treating as an anomaly, what the French philosopher had shown to be none, but had referred with equal sagacity and industry to general principles. After the labours ofBergmannandBer- thollet, chemistry seemed to leave little further to be desired, relative to the mu- tual decomposition of soluble salts. But the insoluble salts are likewise susceptible of exchanging their principles with a great number of the soluble salts. ''This class of phenomena," says M. Dulong, " though almost as numerous as that which embraces the soluble salts, and capable of lions which would be requisite to asceiv tain them. M. Dulong found by experiment, that all the insoluble salts are decomposable by the carbonate of potash or the carbo- nate of soda, and in some instances with curious phenomena. When sulphate of barytes, phosphate of barytes, or oxalate of lime, is boiled with solution of bicarbo- nate, or carbonate of potash, a considera- ble pan of the insoluble sulphate is con- stantly transformed into a carbonate of the same base ; but on reaching a certain li- mit, the decomposition stopped, although there remained sometimes a very conside- rable quantity of the soluble carbonate not decomposed. M. Dulong convinced him- self, that the different degrees of concen- tration of the alkaline solution, produced but very slight variations in the results of this decomposition. He took 10 grammes of dry subcarbonate of potash, and 7.66, being their equivalent proportion, of dry subcarbonate of soda; quantities contain- ing each 3.07 grammes of carbonic acid. They were separately dissolved in 250 grammes of water, and each solution was kept in ebullition for two hours, on 8 grammes of the sulphate of barytes. On analyzing the two residues, it was found that the potash experiment yielded 2.185 grammes, and the soda only 1.833; or in the proportion of 6 to 5. Is this difference to be ascribed to the difference in the at- tractive forces of the two alkalis ; to the more sparing solubility, or greater attrac- tive force of the sulphate of potash ; or to both causes conjointly ? Since the alkaline carbonates lose their decomposing agency when a certain pro- portion of the alkaline sulphate is formed, M. Dulong tried to ascertain the limits by the following experiment: 7 grammes of sulphate of potash, with 6 of subcarbo- nate, dissolved in 250 of water, were boil- ed with the sulphate of barytes for several hours, without the least trace of decompo- sition being evinced. The supernatant li- po < affording new resources to analysis, has quid, filtered, and boiled on carbonate of -i barytes, produced a considerable quantity of sulphate ; but ceased acting before this sulphate of potash was exhausted. The same phenomena were obtained with car- bonate and sulphate of soda. " Lastly, the sulphate of potash and the sulphate of soda alone, and perfectly neutral, re-acted likewise upon the carbonate of barytes, and produced on one part, sulphate of barytes, but on the other the subcarbonate of potash or soda which remained in solu- tion, together with the portion of the sul- phate which resisted the decomposition. 20 grammes of crystallized sulphate of .so- il ot yet been examined in a general man- ner." The action of the soluble carbonates on the insoluble salts, is the only one which had been at all studied. Thus carbonates of potash and soda in solution, had been employed conveniently to decompose sul- phate of barytes. M. Dulong had an op- portunity in some particular researches, to bserve a considerably extensive number facts, relating to the mutual decompo- sition of the soluble and insoluble salts, and endeavoured, he says, to determine the general cause of these phenomena, and the method of foreseeing their results, without being obliged to retain by an ef- fort of memory, of which few persons Would be capable, all the direct observa- da, and 10 grammes of sulphate of potash, were separately dissolved in 260 of water, Each solution was boiled for 2 hours on 20 grains of carbonate of barytes. The ATT ATT sulphate of soda produced 10.17 gr. of sulphate of barytes, and the sulphate of potash 9.87." Had 108 of sulphate of potash been employed, which is the true equivalent of 200 sulphate of soda in crys- tals, a somewhat larger product would have been obtained than 9.87. This ex- periment, however, is most satisfactory with regard to the amount of decomposi- tion. The mutual action of the insoluble carbonates, with the soluble salts, whose acids form, with the bases of these carbo- nates, insoluble salts, is equally general with that of the soluble carbonates on the insoluble salts. The following is M. Du- long's table of results : Carbonate of Earytes. Carbo- nate of Stron- tiuu- Cnrbo-l nate of Lime. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id Car bo- mteof Lead. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Sulphate of Potash Soda Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Id. Phosphate of Soda Sulphite of Potash Phosphite of Potash Soda Borate of Soda Arseniate of Potash Soda Oxalate of Potash Ammonia Fluate of Soda Chromate of Potash All those salts which have ammonia for their base, are completely decomposed by the insoluble carbonates found in the same column. The new insoluble salt replaces the carbonate which is decomposed, and the carbonate of ammonia flies off'. Hence, if a sufficient quantity of insoluble carbo- nate be present, the liquid will become pure water. When the soluble salt has an insoluble base, the decomposition does not meet with any obstacle, but continues until the liquid becomes mere water. Thus, solu- tion of sulphate of magnesia, boiled with carbonate of barytes, will be resolved into an insoluble carbonate and sulphate, pro- vided enough of carbonate of barytes be present. Otherwise a portion of the mag- nesian carbonate being dissolved in its own sulphate, gives alkaline properties to the solution. If the base be metallic, it almost always forms a salt with excess of oxide, which being insoluble, precipitates. The general inferences of M. Dulong's inquiries are the following: 1. That all the insoluble salts are decomposed by the subcarbonates of potash or soda, but that a mutual exchange of the principles of these salts cannot in any case be complete- ly made ; or in other words, that the de- composition of the subcarbonates is only partial. 2. That all the soluble salts, of which the acid forms, with the base of the insoluble carbonates, an insoluble salt, are decomposed by these carbonates, un- til the decomposition has reached a certain limit which it cannot pass. When a soluble subcarbonate acts on an insoluble salt, in proportion as the carbonic acid is precipitated on the base of the in- soluble salt, it is replaced in the solution by a quantity of another acid, capable of completely neutralizing the alkali. Thus, during the whole course of the decompo- sition, fresh quantities of neutral salt re- place the corresponding quantities of an imperfectly saturated alkaline compound; and if we view the excess of alkaline pow- er in the undecomposed subcarbonate, or its unbalanced capacity of saturation, as acting upon both acids, it is evident that in proportion as the decomposition ad- vances, the liquid approaches more and more to the neutral state. In the inverse experiment, a contrary change supervenes. Each portion of the acid of the soluble salt, (sulphate of soda for example), which is precipitated on the base of the insoluble carbonate, is replaced by a quantity of carbonic acid, which forms with the cor- responding base, an alkaline subcarbo- nate ; and the more of the first acid is pre- cipitated upon the earthy base, the more subcarbonate the liquid contains, and the further does its state recede from neutrali- zation. This consideration seems to lead directly to the following theory of these decompositions. It is known, says M. Dulong, that all the salts, even those which possess the great- est cohesion, yield to caustic potash or so- da, a more or less considerable portion of their acid, according to circumstances. Now the alkaline subcarbonates may be considered as weak alkalis, which may take from all the insoluble salts a small quantity of their acids. This effect would soon he limited if the alkali were pure, in consequence of the resistance offered by the pure and soluble base. But the latter meeting in the liquid, an acid with which it can form an insoluble salt, unites with it, and thus re-establishes the primitive con- ditions of the experiment. The same ef- fects are produced successively on new portions of the bodies, till the degree of saturation of the liquid is in equilibrium with the cohesive force of the insoluble salt, so that the feebler this resistance may be, the more progress the decomposition will make. And again, when an insoluble carbonate is in contact with a neutral solu- ble salt, the base of the carbonate will tend ATT ATT to take part of the acid of the neutral salt ; and if, from this union, an insoluble salt can result, the force of cohesion peculiar to this compound, will determine the forma- tion. The carbonic acid, released from the attraction of the earthy base by the fixed acid, instantly attaches itself to the surrounding 1 alkali, forming 1 a subcarbo- nate which replaces the decomposed neu- tral salt. The precipitation of the fixed acid on the insoluble carbonate, and the absorption of carbonic acid by the liquid continues, until the alkalinity thereby de- veloped, becomes so strong 1 as to resist the precipitation of the acid; thus forming a counterpoise to the force by which that precipitation was accomplished. All ac- tion then ceases, so that the mere cohesion the insoluble salt possesses, the greater will be the proportion of acid taken from the soluble salt. When the carbonate of potash can no longer decompose the sulphate of barytes, the carbonic acid which remains in the so- lution, is to the sulphuric acid nearly in the ratio of 3 to 1 ; and when the sulphate of potash can no longer act upon the car- bonate of barytes, these two acids are nearly in the ratio of 3 to 2 ; whence it follows, that the first liquor is much more alkaline than the second. It is easy to account for this difference by examining the conditions of the equili- brium established in the two cases. When the sulphate of potash no longer decom- poses the carbonate of barytes, it is be- cause the excess of alkali, developed in the liquid, forms a counterpoise to the power with which sulphate of barytes tends to be produced in these circumstan- ces. And when the subcarbonate of pot- ash can no longer decompose the sulphate of barytes, it is because there is not such an excess of alkali in the liquid, as is capa- ble of overcoming the cohesion and attrac- tion between the elements of that salt. Now we know, that it requires a greater force to overcome an existing attractive power, than to maintain the quiescent con- dition. Therefore the subcarbonate of potash ought to cease to decompose the sulphate of barytes, before the sulphuric and carbonic acids are in the same rela- tion in which they are found, when the equilibrium is established by the inverse experiment. Hence we see, that a mix- ture of sulphate and subcarbonate of pot- ash, in which the proportions of their two acids shall be within the limits pointed out, will have no action either on the sul- phate or carbonate of barytes. For the other insoluble salts, there will be other relations of quantity ; but there is always a certain interval, more or less considera- ble, between their limits. The mutual action of sulphate of soda and carbonate of b.arytes is almost in&tsntaneons, It is sufficient to pour a boiling hot solution of the sulphate, on the carbonate placed on a filter, in order that more than three- fourths of the sulphuric acid be precipi- tated, and replaced by a corresponding quantity of carbonic acid. In the first part of the Philosophical Transactions for 1809, we have tables of elective attractions by Dr. Thomas Young, a philosopher of the very first rank, whom the late ingenious Dr. Wells pronounced the most learned man in England. These have been unaccountably overlooked by our different systematic writers, though they are, both in accuracy and ingenuity, far superior to the tables which, with un- varying routine of typography, are copied into their compilations, I conceive it will be doing an essential service to chemical students, to lay before them the tables of lH^ Young, accompanied with his admira- ble remarks on the sequences of double decompositions. Attempts have been made, by several chemists, to obtain a series of numbers, capable of representing the mutual attrac- tive forces of the component parts of dif- ferent salts ; but these attempts have hitherto been confined within narrow li- mits, and have indeed been so hastily abandoned, that some very important con- sequences, which necessarily follow from the general principle of a numerical re- presentation, seem to have been entirely overlooked. It appears that nearly all the phenomena of the mutual actions of a hun- dred different salts may be correctly re- presented by a hundred numbers, while, in the usual manner of relating every case as a, different experiment, above two thou- sand separate articles would be required. Having been engaged in the collection of a few of the principal facts relating to chemistry and pharmacy, Dr. Young was induced to attempt the investigation of a series of these numbers ; and he has suc- ceeded in obtaining such as appear to agree sufficiently well with all the cases of double decompositions which are fully established, the exceptions not exceeding twenty, out of about twelve hundred cases enumerated by Fourcroy. The same num- bers agree in general with the order of simple elective attractions, as usually lail down by chemical authors ; but it was of so much less importance to accommodate them to these, that he has not been very solicitous to avoid a few inconsistencies in this respect ; especially as many of the ba- ses of the calculation remain uncertain? and as the common tables of simple elec- tive attractions arc certainly imperfect, if they are considered as indicating the order of the independent attractive forces of the substances concerned. Although it can- not be expected that these numbers should be aceurata measures of the forces which ATT ATT they represent, yet they may be supposed to be tolerable approximations to such measures ; at least, if any two of them are nearly in the true proportion, it is proba- ble that the rest cannot deviate very far from it : thus, if the attractive force of the phosphoric acid for potash is about eight- tenths of that of the sulphuric acid for barytes, that of the phosphoric acid for barytes must be about nine-tenths as great. But they are calculated only to agree with a certain number of phenomena, an O > 2QO ^ ^3 [- op bd llflflllll ' P S ! *5 P p 52. 3. ; P P M S P ' P 5 g. P 3. a W o IT* 1? - M gg g c re o ta ^! e ^^ , , O3 ^ ^ p . c s- r si 2 CD i H c^ hH P I rt- O Ci ^ H ffl 1 E fft CO >, a S-' p* ^ ^j 1 5* i ? 3 > 5T o bs g 3 i s. P* 1 w p* i . M 3 . S- O j. *+ 5' CO ^ w> v?^ 1 1 w p- 3 "^ r*> O ? ^ b w 4* Glycina? 600 520 Glycina 580 Glycina Alumina 529* Alumina 51'4 515 Alumina 575 AH n: *^ia Zirconia 524* Zirconia ? 588 510 Zirconia 570 ^tfOoaia SUCCINIC. SUBERIC. CAMPHORIC. CITRIC. Barita 930 Barita 800 Lime Lime 731 Lime 866 Potash 745 Potash Barita 730 Strontia? 740 Soda 740 Soda Strontia 618 (Magnesia)732 Lime 735 Barita Magnesia 615 Potash 612 Ammonia 720 Ammonia Potash 610 Soda 607 Magnesia 700 Glycina ? Soda 605 Ammonia 605 Gl>cina? 5;,5? Alumina Ammonia 603 Magnesia Alumina 530 Zirconia ? Glycina ? 415 ? Glycina ? 510 Zirconia? 525? Magnesia Alumina 410 Alumina 505 Zirconia 405 Zirconia? 500 LACTIC. BENZOIC. SULPHUROUS. ACETIC. Barita 729 White oxide of Barita 592* Barita 594 Potash 609 arsenic Lime 516* Potash 486 Soda 604 Potash 608 Potash 488* Soda 482 Strontia 603 Soda 603 Soda 484* Strontia 480 Lime (732) Ammonia 599 Strontia (527)* Lime 470 Ammonia 601 Barita 597 Magnesia 439* Ammonia 432 Magnesia 575 Lime 590 Ammonia 433* Magnesia 430 Metallic oxides Magnesia 560 Glycina 355* Metallic oxides Glycina 410 Glycina? 400? Alumina 351* Glycina 395 Alumina 405 Alumina 395 Zirconia 347* Alumina 391 Zirconia 400 Zirconia? 390? Zirconia 387 Mucic ? BORACIC. NITROUS ? PHOSPHOROUS, Barita 900 Lime 537* Barita 450 Lime Lime 860 Barita 515* Potash 440 Barita Potash 484 Strontia 513* Soda 437 Strontia Soda 480 Mofiesia(459)* Strontia 430 Potash Ammonia 431 Potash 482* Lime 425 Soda Glycina 425 Soda 479* Magnesia 410 Magnesia ? Alumina 420 Ammonia 430* Ammonia 400 Ammonia Zirconia 415 Glycina 388* Glycina 340 Glycina Alumina 385* Alumina 336 Alumina Zirconia 382* Zirconia 332 Zirconia CARBOKIC. PRUSSIC. Barita 420* Barita 400 Strontia 419* Strontia Lime (423)* Potash 300 Potash ? 306* Soda 298 Soda 304* Lime 290 Magnesia (366)* Magnesia 280 Ammonia 339* Ammonia 270 Glycina 325* Glycina? 260 Alumina 323* Alumina ? 258 Zirconia 331* Zirconia ? 256 ATT ATT TABLES OF SIMPLE ELECTIVE ATTRACTIONS, FROM BERGMANN. I. WATER AND COMBUSTIBLE SUBSTANCES IN THE HUMID WAY. WATER. SULPHUR. SALINE SULPIIUUKTS. ALCOHOL. ETHER. Potash Oxygen Oxygen Water Alcohol Soda Molybdic oxide Oxide of gold Ether Volatile oils Ammonia and acid silver Volatile oils Water Deliquescent Oxide of lead mercury Ammonia Sulphur salts tin arsenic Fixed alkali Alcohol silver antimony Alkaline sul- Carbonate of mercury bismuth phurets ammonia arsenic copper Sulphur Ether antimony tin Muriates Sulphuric acid Non-deliques- iron Potash lead nickel Phosphoric acic cent salts Soda Barytes cobalt manganese iron FAT OILS. VOLATILE OILS. Lime Other metallic Barytes? Ether Magnesia oxides Strontian ? Alcohol Phosphorus Carbon Lime Fat oils Fat oils Water Metallic oxides Fixed alkalis Ammonia Ether Hydrogen? Alcohol Ether Ethel- Volatile oils Fixed alkalis Sulphur Phosphorus Ammonia Sulphur IN THE DRY WAY. Phosphorus SULPHURETTED Oxygen Manganese Potash Iron Barytes Soda Copper Potash Ton Tin Soda Copper Lead Lime rin Silver Ammonia Lead Gold Magnesia Silver Antimony Zircon Cobalt Cobalt Nickel Nickel j Bismuth Bismuth Antimony Mercury Mercury Arsenic (Arsenic Carbon ? Uranium ? Molybdena Tellurium ATT ATT TABLE OF SIMPLE ELECTIVE ATTRACTIONS. II._ OXYGHEN AND METALS. IN THE HUMID WAY. OXIDE OF OXIDE OF OXIDE OF OXIDE OF OXIDE OF^ OXYGEK. GOLD. SILVER. PLATINA. MERCURT. 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 tartaric ric tartaric sulphuric phospho- Copper phospho- sulphu- phospho- mucic ric Platinum ric rous ric tartaric muriatic Mercury acetic nitric oxalic citric sulphu- ("Palladium sebacic arsenic citric malic rous J Rhodium prussic fluoric acetic sulphu- suberic j Iridium ?ixed alkalis tartaric succinic rous nitric ^Osmium Ammona 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 IV J 11 1 " IN THE DRY WAY. r ixed alkalis Fat oils Ammonia GOLD. SiLVEK. PLATINA. MERCURY. LEAD. Titanium Mercury Lead Arsenic Gold Gold Manganese Copper Copper Gold Silver Silver Zinc Silver Mercury Copper rMatina 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 Cobalt Iron Platina Iron Manganese Nickel Cobalt Hopper Antimony Platina Arsenic Antimony Zinc Zinc Manganese Arsenic Zinc Nickel Nickel Arsenic Iron Iron 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 Phosphorus Sulphur Azote The column under oxygen is divided into two parts. The first exliibits the order in which the metals precipitate one another from acid solutions ; the second, according to Vauquelin, shows the affinities of the metals for oxygen, represented by the difficulty with which their oxides are decompo- sed bvheat. It is different from Berqrmann's column. Chlorine * & ATT ATT TABLE OP SIMPLE ELECTIVE ATTRACTIONS. METALS (CONTINUED). IN THE HUMID WAY. OXIDE OF OXIDE OF OXIDE OF OXIDE OF OXIDE or OXIDE OF COPPER. IHOTV. Tw. BISMUTH. NlCKE',. ARSEMC. Acids, gallic oxalic Acids, gallic oxalic Acids, gallic tartaric Acids, oxalic arsenic Acids, oxalic muriatic Acids, gallic 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 ci ric citric succinic citric fluoric citric acetic acetic citric acetic succinic acetic prussic arsenic arsenic boracic citric boracic carbonic boracic acetic prussic acetic prussic Ammonia prussic prussic carbonic boracic Potash carbonic Fixed ni kalis Potash prassic Soda Ammonia Ammonia Soda carbonic Ammonia Fat oils Ammonia Water Compound salts Fat oils =sr IN THE DRY WAY. T. BISMUTH. NICKEL. ABSEMC. Gold Nickel Zinc Lead Iron Nickel Silver Cobalt Mercury Silver Cobalt Cobalt Iron Arsenic Manganese Zinc Manganese Arsenic Copper Gold Copper Antimony Gold silver Gold Mercury Antimony Tin Arsenic Copper Gold Tin Copper Iron Silver Tin Antimony Platina Silver Tin Lead Iron Copper Platina Antimony Platina Lead Gold Tin Lead Antimony Platina Manganese Nickel Nickel Iron Bismuth Lead Platina Zinc Nickel Bismuth Cobalt Mercury Alkaline sul- phurets Bismuth Lead Alkaline sul- phurets Sulphur Arsenic Platina Bismuth Cobalt Alkaline sul- phurets Zinc Alkaline sul- phurets Sulphur Silver Zinc Alkaline sul- Shurets phur Antimony Alkaline sul- phurets Sulphur Sulphur Sulphur ATT ATT TABLE OF SIMPLE ELECTIVE ATTRACTIONS. METALS -(CONCLUDED.) IX THE HUMID WAY. OXIDE OF OXIUE OF OXUIE OF OXIDE OF OXIJJE OF OXIDE OF COBAi.T. ZlKC, 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 nitri ric Alkalis ric tartaric tartaric nitric Mercury fluoric phospho- mucic sulphuric muclc ric phospho- muriatic ~ succinic citric ric arsenic OXIDE OP citric succinic citric acetic URANIUM. acetic arsenic fluoric arsenic succinic fluoric prussic carbonic Acids, sulphu- boracic acetic arsenic ric prussic boracic acetic nitro-mu- carbonic prussic boracic riatic Ammonia carbonic Fixed alkalis prussic carbonic muriatic nitric Ammonia Sulphur phospho- Fixed alkalis ric Ammonia acetic gallic prussic carbonic IN THE DRY WAY. Sulphur COBALT. ZINC. ANTIMONY. MANGANESE. TJELLIBIUM. Iron Copper ron Hopper Mercury Nickel Antimony Copper Iron Sulphur Arsenic Tin Tin Gold Copper Mercury ^ead Silver Gold Silver Nickel Tin Platina Gold Silver Alkaline sul- Tin Cobalt Bismuth phurets Antimony Arsenic Zinc Zinc Platina Sold Alkaline sul- Bismuth Platina phurets Lead Mercury Sulphur Nickel Arsenic Iron Cobalt Alkaline sul- phurcts Sulphur ATT ATT SCHEMES OF DOUBLE AFFINITIES IN THE HUMID \VAY, TSulphuric acid Sulphate of <( 50 Magnesia | Fluoric \_Magnesia acid ^ - " - Aneni- Oxygen*} ^ Oxygen ous acid 1 > l^ArsenicJ J Arsenic acid acid Sulphuret oi lime Sulphate of lime "Lime 54 Sulphuric acid ^Sulphur Nitre Nitrate of lime "Nitric acid 44 Sulphuric ^Lime 54 acid Sulphate of lime Acetate of potash 26 Acetic acid Sulphupet of potash Sulphate ofpot- ^Sulphur v ^ Muriate of potash "Potash 32 Muriatic acid 62 -f 23 54 85 Sulphu- j-ic acid 86 Limo_ Sulphate of lime Muriate ^of lime "Potash 58 Nitric "\ fPotash 62 Sulphu-^ Sulphate of pot- ^ " icl 62 iKitrate fofleaa ric acid Muriate j of pot- -^ 32 -j- 54 = 86 Bul- -phute of ash frsll lime Sulphuric Oxide of { 1 Muriatic ? acid lead J L acid 85 Limej Sulphate of lead Nitrate of ammonia Nitrate of soda r -^ 'Ammo- 38 Nitric~) "Soda Nitric " nia ucid acid Sulphate Nitrate of am- s 46 Vof mer- Com- < >N5trate moiiia cury mon salt of silver Sulphuric Oxide of Muriatic acid mercury., acid Silver^ V- J ^ j Sulphate of mercury Muriate of silver AUR AX1 * AtreiTE. Pyroxene of Haiiy. This mineral is for the most part crystallized in small six or eight-sided prisms, with dihe- dral summits. It is found also in grains. Its colours are green, brown, and black. Internal luster shining. Uneven fracture. Translucent. Easily broken. It Scratches g-lass. Sp. gr. 3.3. Melts into a black enamel. Its composition according to Klaproth, is 48 silica, 24 lime, 12 oxide of iron, 8.75 magnesia, 5 alumina, 1 manga- nese It is met with among volcanic rocks but is supposed to have existed prior to the eruption, and ejection of the lava. Larg* crystals of it are also found in ba- salt, 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 seve- ral of the Hebrides. Sahlite and coccolite are considered to be varieties of augite.* AUKUM FUL^II* ANS. See FcMiiTfATTjrG. * AUHUM GUAPHICUM. See OiiEsof Gold* AURCM Musivtnvr, or MOSAICUM. A com- bination of tin and sulphur, which is thus made : Melt 12 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 aimim Tnusivum, 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 ammonia; while the alkali of that salt, combining with a portion of the sulphur, flies off in the form of a sulphuret. The combination of tin and muriatic acid sub- limes ; and is found adhering to the sides ofthemalrass. The mercury which served to divide the tin, combines with part of the sulphur, and forms cinnabar, which also sublimes ; and the remaining 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 in- dicate the reasons why such an indirect and complicated process should be re- quired to form a simple combination of tin and sulphur. It does not appear that the proportions of the materials require to be strictly at- tended to. The process of the Marquis put into a linen cloth, and repeatedly kneaded with hot water : the first wateiv 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, th an the foreign matter with which it is associated. \Vhen azure-stone has its co- lour altered by a moderate heat, it is reck- oned bad. Messrs. Clement and Desormes consider the extraction of ultramarine as a species of saponification.* * AZUUITB, the LAZULITE of Werner and Haiiy. 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 oc- curs in Vorau in Stiria in a gangue o 2uartz ; but the finest specimens om the bishopric of Salzburg,* B BALANCE. The beginning and end of every exact chemical process consists in weighing 1 . With imperfect instruments this operation will be tedious and inaccu- rate; but with a good balance, the result will be satisfactory; and much time, which is so precious in experimental researches, will be saved. The balance is a lever, the axis of mo- tion of which is formed with an edge like that of a knife; and the two dishes at its ex- tremities are hung upon edges of the same kind. 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 tmter edges are called points of suspension, and the inner the fulcrum. 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 ed- ges lie all in the same right line, the bal- ance will have no tendency to one position more than another, but will rest in any po- sition 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 ful- crum, 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: and, if disturbed from this po- sition, and then left at liberty, it will vi- brate, and at last come to rest on the level. Its vibrations will be quicker, and its ho- rizontal 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 join- ing the points of suspension, and these be loaded, the beam will overset, unless pre- vented by the weight of the beam tending to produce a horizontal position, as in 3. In this last case, small weights will equili- brate, 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 join- ing the points of suspension, the beam will come to the horizontal position, unless pre- vented 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, provided the standard weight itself be first counterpoised, then taken out of the scale, and the tiling to be weighed be put into the scale, and adjusted against the counterpoise; or when proportional quantities only are considered, as in che- mical and in other philosophical experi- ments, the bodies and products under exa- mination 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 indis- pensably necessary, that their relative lengths, whatever they may be, should con- tinue invariable. For this purpose, it is ne- cessary, either that the three edges be all truly parallel, or that the points of suspen- sion 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 usual- ly 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, ail the parts naturally fail into the same bearing. The balances made in the country have the fulcrum edge straight, and confined to one constant bear- ing by two side plates. But the points of suspension are referred to notches in the edges, like the London balances. The bal- ances here mentioned, which come from the country, are enclosed in a small iron japanned box; and are to be met with at the Birmingham and Sheffield warehouses, though less frequently than some years ago; because a pocket contrivance for weighing guineas and half-guineas has got posses- sion 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 22 BAL BAL '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 1 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 scalesfthat balance will turn, and the points of suspen- sion 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 contain- ing 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; conse- quently all accurate weighing must be slow. If the indexes of two balances be of equal lengths, that index which is connected with the shorter balance will move proportional- ly quicker than the other. Long- beams are the most in request, because they are thought to have less friction; this is doubt- ful; 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 nice experiments, but are likewise much more expeditious than others in com- mon weighing. If a pair of scales with a certain 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 ob- served 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 tre- mulous motion in its parts. Thus, if the edge of a blunt saw, a file, or other similar instrument, be drawn along any part of the case or support of a balance, it will pro- duce 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, whatever may be the load; except so far as a greater load will produce a greater fric- tion. 14. But a balance, the horizontal tenden- cy of which depends only on the elevation of the fulcrum, as in 5. will be less sen- sible 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 tendency 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 a useful contrivance. 16. Weights are made by a subdivision of a standard weight. If the weight be con- tinually 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 examination. Granulated lead is a very convenient substance to be used in this operation of halving, which, how- ever, is very tedious. The readiest way to subdivide small weights, consists in weigh- ing a certain quantity of small wire, and afterward cutting it into such parts, by measure, as are desired; or 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 quantity (as, for ex- ample, a grain) of these rings be weighed, and the number then reckoned, the grain may be subdivided in any proportion, by di- viding that number, and makingthe weights equal to as many of the rings as the quo- tient 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-lUlhs to 525 rings, Sic. Small weights may be made of thin leaf brass. Jewellers' foil is a good material for weights below 1-lOth of a grain, as low as to l-100th of a grain; and all lower quantities may be either esti- EAL BAL mated by the position of the index, or shown by actually counting- the rings of wire, the value of which has been deter- mined. 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 pre- ference. With regard to the number of weights the chemists ought to be provided with, writers have differed according to their habits and views. Mathematicians have computed the least possible number, with which all weights within certain lim- its might be ascertained; but their deter- mination 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 determine 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 con- venient number for ascertaining his in- quiries 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 grains, 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 num- ber; 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. 100 g. 90 g. 80 g. 70 g. 60 g. 50 g. 40 g. 30 g. 20 g. 10 g. 9 g. 8 g. 7 g. 6 g. 5 g. 4 g. 3 g. 2 g. 1 g. T 9 o g. T V g- T 7 o g- T 6 o g- T 5 o g- T 4 o g To g- T 2 o ' To g- Tfo g- TO- g' TO g- ToTT g' TO g' TOO g- TW g' To g- TW g- With these the philosopher 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. I shall conclude this chapter with an ac- count of some balances I have seen or heard of, and annex a table of the corres- pondence of weights of different countries. Muschenbroek, in his Cours de Physique, (French translation, Paris, 1769), torn. ii. p 247. says, he used un ocular balance of great accuracy, which turned (trebuchoit) with -L of a grain. The substances h e weighed were between 200 and 300 grains. His balance therefore weighed tothe ygiJ^o" part of the whole; and would ascertain such weights truly to four places of figures. In the Philosophical Transactions, vol. Ixvi. p. 509. mention is made of two accu- rate balances of Mr. Bolton; and it is said that one would weigh a pound, and turn with T I Q. of a grain. This, if the pound be avoirdupois, is 700 - QO of the weight; and shews that the balance could be well depend- ed on to four places of figures, and probably to five. The other weighed half an ounce, and turned with -fa of a grain. This is 2To o- of the weight. In the same volume, p. 511. a balance of Mr. Read's is mentioned, which readily turned with less than one pennyweight, \vhen loaded with 55 pounds, before the Royal Society; but very distinctly turned with four grains, when tried more patiently. This is about -g-g-^Q-o P art ^ ^ le weight; and therefore this balance may be depend- ed on to five places of figures. Also, page 576. a balance of Mr. White- hurst's weighs one pennyweight, and is sen- sibly affected with -^Vo of a grain. This is 4ird-oo Part of the weight. I have a pair of scales of the common construction, 8. made expressly for me by a skilful workman in London. With 1200 grains in each scale, it turns with -f$ of a grain. This is B -^- - - of the whole; and therefore about this weight may be known to five places of figures. The proportional delicacy is less in greater weights. The beam will weigh near a pound troy; and when the scales are empty, it is affected by __i__ of a grain. On the whole, it may be usefully applied to determine all weights be- tween 100 grains and 4000 grains to four places of figures. A balance belonging to Mr. Alchorne of the Mint in London, is. mentioned, vol. Ixxvii. p. 205. of the Philosophical Transac- tions. It is true to 3 grains with 15 Ib. an end. If these were avoirdupois pounds, the weight is known to j-g-^0-^ part, or to four places of figures, or barely five. A balance, (made by Ramsden, and turn- ing on points instead of edges) in the pos- session of Dr. George Fordyce, is mentioned in the seventy-fifth volume of the Philoso- phical Transactions. With a load of four or five ounces, a difference of one division in the index was made by T6 Vo of a ranl - This is -g-g-jVo-or part of the weight, and consequently this beam will ascertain such weights to five places of figures, beside an estimate figure, BAL BAL I have seen a strong- balance in the pos- session of my friend Mr. Magellan, of the kind mentioned in 15. which would bear several pounds, and showed -JLof a grain, with one pound an end. This is 7( y-g- 6 of the weight, and answers to five figures. But I think it would have done more by a more patient trial than I had time to make. The Royal Society's balance, which was lately made by Itamsden, turns on steel edges, upon planes of polished crystal I was assured, that it ascertained a weight to the seven-millionth part. 1 was not present at this trial, which must have required great care and patience, as the point of suspension could not have moved over much more than the T |~g- of an inch in the first half minute; but, from some trials which I saw, I think it probable that it may be used in general practice to determine weights to five places and better. From this account of balances, the stu- dent 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 deductions in chemistry, that depend on a supposed accuracy in weighing, which practice does not authorise. In gene- ral, where weights are given to five places of figures, the last figure is an estimate, or guess figure; and where they are carried farther, it may be taken for granted, tbat 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 procured, by means of the ambassadors of France, resident in various places; and these were compared by Mons. Tillet with the standard mark in the pile preserved in the Gourde 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 follows that this balance was a good one, and would exhibit proportions to four places, and a guess figure. The results are contained in the fol- lowing table, extracted from Mons. Tillet'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 weigh- ing came no nearer than about two-tenths. The weights of the kilogramme, gramme, decigramme, and centigramme, which are now frequently occurring in the French che- mical 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 16 ounces, for merchan- dise, ----._ The common pound varies very consi- derably in other towns of the'canton. Berne. Apothecaries' weight of 8 ounces, JBonn. ..... Brussels. The marc, or original troyes wt. Cologn. The marc of 16 loths, Constantinople. The cheki, or 100 drachms, Copenhagen. Goldsmiths' weight, comO monly supposed equal to the marc > of Cologn, j Copenhagen. Merchants' \veight of 16 loths, Dantzic weight, commonly supposed ^ equal to the marc of Cologn, Florence. The pound (anciently used bv"J the Romans), Genoa. The peso sottile, Genoa. The peso grosso, - Hamburgh weight, commonly supposed > equal to the Cologn marc, Hamburgh. Another weight, . . Liege. The Brussels marc used; but the 7 weight proved, . The marc, or half pound, . . marc. OS. 7 gros. o grains. 16 F. grains. 4408 E. grains. 3616.3 1 $ 4 4648 5813.2 2 1 i 6 9834 8067.7 __ 7 5* 26 4454 3654. 7 5 6| 4398 3608.6 1 21 4629 3797.6 7 5 11 4403 3612.2 1 2 3 28 6004 4925.6 7 5* WJ 44381 3641.2 1 1 22$ 4702$ 3857.9 7 5 3* 95| 3606. 1 3 i 20 6392 5244. 1 2 2i 30 5970 4897.7 1 2 3 5 5981 4906.7 7 5 n 4399| 3609.4 7 7 23 4559 3f40.2 1 24 4632 3800.1 7 3 kA o4 4318 3542.4 BAI- KAL Place and Denomination of Weights. London. The pound troy, ... London. The pound avoirdupois, - Lucca. The pound, - - Madrid. The marc royal of Castile, 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 647 ducats, 5 Ratisbon. The marc of 8 ounces, Ratisbon. The pound of 16 ounces, - - Rome. The pound of 12 ounces, Stockholm. The pound of 2 marcs, - - Stuttgard. (The Cologn marc), Turin. The marc of 8 ounces, At Turin they have also a pound of 12 of the above ounces. But, in their apothecaries* 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 pounds 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, ... The gramme, The decigramme, ... The centigramme, ... See TABLES of WEIGHTS and MEASURED in the Appendix. ware. 02. gros. grains. F. grains. E. grains. 1 4 H 1 7021 5760. 1 6 6i 6 8538 7004.5 1 3 23 63 5 9 5217. 7 4 8* 4328 3550.7 1 2 2 21 5961 4890.4 _ 7 5 10 4402 3611.5 __ 7 5 33i 4425 3660.2 3 . 7^ __ 14364^ 11784. 7 5 11 4403i 3612.3 1 2 si 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 11| 4403| 3612.6 1 ~~" 22i 4630* 3799. 1 5 2 12 7644 6271. 1 7 89895 7374.5 1 1 6i 24 5676 4656.5 1 1 1 16 5272 4325. 1 1 1 26 5282 4333.3 __ ___ 1.21895 1. _ 1. 0.82039 4 5 35 | 18827.15 15445.5 _ _ 18.827 15.445 1.8827 1.5445 .18827 .15445 * The commissioners, appointed by the British government for considering the sub- ject of weights and measures, gave in their first report on the 24th June 1819. The fol- lowing is the substance of it : " 1. With respect to the actual magnitude of the standards of length, the commis- sioners are of opinion, that there is no suffi- cient reason for altering those generally employed, as there is no practical advan- tage in having a quantity commensurable to any original quantity 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 measures at present employed in this coun- try, 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 peculiar advantage in the duo- decimal scale; and for the operation of weighing and of measuring capacities, the continual division by two, renders it practi- cable to make up any given quantity with the smallest possible numberof weights and measures, and is far preferable in this res- pect to any decimal scale. The commis- sioners therefore recommend, that all the multiples and subdivisions of the standard to be adopted, should retain the same re- lative proportions to each other as are at present in general use. " 3. That the standard yard should be that employed by Gen. Roy in the measurement of a base on Hounslow Heath, as a founda- tion 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 in- ches of the standard scale, and that the length of the French metre, as the 10 mil- lionth part of the quadrantal arc of the meridian, has been found equal to 39.3694 inches. BAL BAR " 5. That 10 ounces troy, or 4800 grains, should be declared equal to the weight of 19 cubic inches of distilled water, at the temperature of 50, and that one pound avoirdupois must contain 7000 of these grains. " 6. That the standard ale and corn gal- lon should contain exactly ten pounds avoir- dupois of distilled water at 62 Fahr. being nearly equal to 277.2 cubic inches, and agreeing with the standard pint in the Ex- chequer, which is found to contain exactly 20 ounces of water. The customary ale gal- lon contains 282 cubic inches, and the Win- chester corn gallon 269, or according to other statutes 272i cubic inches; so that no inconvenience can possibly be felt from the introduction of a new gallon of 277.2 inches. The commissioners have not decided upon the propriety of abolishing entirely the use of the wine gallon." The following elegantly simple relations of weight and measure were suggested by Dr. Wollaston, in his examination before the committee; and it is to be hoped they will be 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 inconveniences 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 that which contains 10 Ibs. of water at 564 F.; then, since the cubic foot of water weighs 1000 oz. at 56, | pint = 10 oz. = T ^Q- cubic foot = 17.28 inches. Pint = 20 oz. = 34.56 inches. Bushel = 80 Ib. = 2211.84 And the simple proportions above alluded to will be found as follows: The gallon of 10 Ib. Also, The pint of H Ib. Bushel of 80 Ib. A cylinder of 18 in. diam. Ditto 18| Cubic Inches. 276.48 X If = = 276.48 X Tiz- = 3 = 282.01 230.40 34.56 X 3 = 103.68 2211.84 X || = 2150.40 X 8 = 2208.9J X 8.0105 282 beer gallon. 231 wine gallon. 103.4 Stirlg.jug. 2150,42 Winch, bush. Approximate bush. 221.184 new bush. " 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: On r 1 f 36 ' 1 ^ * s such, that a pendulum of 39.13 inches, vibrates seconds is such, that one cubic foot of water at 56^, weighs 1000 oz. such that 700 grains = 1 P ound (avoirdupois). rv n r . , 7 ma V be such as to contain 10 pounds of distilled water at the One gallon, of 8 pints, temperature of 56^ Fahr. with great convenience." Captain Kater has lately made a small correction on his first determination of the length of the pendulum vibrating seconds in the latitude of London. Instead of 39 13860 inches, as given in the Ph. Trans, for 1818, he has made it 39.13929 inches of Sir Geo. Shuckburgh's standard scale. Mr. Watts, in the 5th number of the Edin- burgh Philosophical Journal, makes it = 39.138666 of the above scale, or = 39.13724D5 of General Roy's scale, at Cap- tain Rater's temperature of 62 Fahr. and 0.9941 of a metre.* ' * BAIKALITE. See TREMOLITE, AS- BESTIFORM.* BALAS, or BALAIS RUBY. See SPI- NELLE. B A L LOO N. Receivers of a spherical form are called balloons. BALLOON. See AEROSTATICS. * BALSAMS, are vegetable juices, either liquid, or which spontaneously become concrete, consisting of a substance of a re- sinous nature, combined with ben zoic acid, or which are capable of affording benzoic acid, by being heated alone, or with water. They are insoluble in water, but readily dissolve in alcohol and ether. The liquid balsams are ccpaiva, opobalsam, Peru, sty- rax, tolu; the'concrete are benzoin, dragon's blood, and storax; which see.* BALSAM OF SULPHUR. A solution of sulphur in oil. * BALDWIN'S PHOSPHORUS. Ignited ni- trate of lime.* * BARIUM. The metallic basis of the earth barytes has been called barium by its discoverer, Sir H. Davy. Take pure barytes, EAR BAB 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 glob- ule 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, con- sisting of mercury and barium. This amal- gam 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 mercury 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 sur- rounded with globules of gas, it sinks im- mediately 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 efferves- ces violently in water, converting this li- quid into a solution of barytes. Sir H. Davy thinks it probable that barium may be pro- cured by chemical as well as electrical de- composition. When chloride of barium, or even the dry earth, ignited to whiteness, 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 dis- appears in the air. The potassium, by being thus transmitted, is converted into potash. From indirect experiments, Sir H.Davy was inclined to consider barytes as composed of 89.7 barium 4- 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 probably very exact. Dr. Clark of Cambridge, by ex- posing dry nitrate of barytes on charcoal, to the intense heat of the condensed hydroxy- gen flame, observed metallic globules in the midst of the boiling fluid, and the charcoal was found to be studded over with innumer- able globules of a pure metal 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 proportions forming 1 , 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 ig- nited nitrate is of a whitish-grey colour; more caustic than strontites, or perhaps even lime. It renders the syrup of violets green, and the infusion of turmeric red. Its specific gravity by Fourcroy is 4. W hen water in small quantity is poured on the dry earth, it slakes like quicklime, but perhaps with evolution of more heat. When swal- lowed it acts as a violent poison. It is des- titute 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 con- tact with atmospheric air, we obtain at first this deutoxide and carbonate of bary- tes; the former 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. Exposed at a moderate heat to carbonic acid, it absorbs it, emitting oxygen, and be- coming carbonate of barytes. The deutoxide is probably decomposed by sulphuretted hy- drogen 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 592 F. the absorption of this gas commences; but at a heat ap- proaching to redness it is exceedingly ra- pid, attended with luminous jets proceed- ing from the surface of the deutoxide. Al- though 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 ba- rytes with an excess of oxygen in a small curved tube standing over mercury, M. Thenard ascertained, that in the deutoxide the quantity of the oxygen is the double of that in the protoxide. Hence the former will consist of 8.7 barium -f- 2 oxygen = 10.7 for its prime equivalent. From the fa- cility with which the protoxide passes into the deutoxide, we may conceive that the former may frequently contain a proportion of the latter, to which cause may be as- cribed in some degree the discrepancies among chemists, in estimating the equiva- lent of barytes. W r ater at 50 F. dissolves one-twentieth of its weight of barytes, and at 212 about one-half of its weight; though M. Thenard BAH BAS in a table, has stated it at only one-tenth. As the solution cools, hexagonal prisms, termi- nated 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 deposit- ed in cubes. They contain about 53 per cent of water, or 20 prime proportions. The su- pernatant liquid is barytes water. It is co- lourless, acrid, and caustic. It acts power- fully on the vegetable purples and yellw r s. Exposed to the air, it attracts carbonic acid, and the dissolved barytes is converted into carbonate, which falls down in insoluble crusts. It appears from the experiments of M. Berthollet, that heat alone cannot de- prive the crystallized hydrate of its wa- ter. After exposure to a red heat, when it ftises like potash, a proportion of water re- mains in combination. This quantity is a prime equivalent = 1.125, to 9.7 of barytes. The ignited hydrate is a solid of a whi- tish-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 atmosphcre.lt yields earburetted hydrogen and carbonate of barytes when heated along with charcoal, provided this be not in excess. Sulphur combines with barytes, when they are mixed together, and heated in a crucible. The same compound is more eco- nomically 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 substance is put into hot water, a powerful action is manifested. The water is decomposed, and two new products are formed; namely, hydrosulphuret, and hy- droguretted sulphuret of barytes, The first crystallizes as the liquid cools, the second remains dissolved. The hydrosulphuret is a compound of 9.7 of barytes with 2.125 sul- phuretted hydrogen. Its crystals should be quickly separated by filtration, and dried by pressure between the folds of porous pa- per. They are white scales, have a silky lustre, are soluble in water, and yield a so- lution having a greenish tinge. Its taste is acrid, sulphureous, and when mixed with the hydroguretted sulphuret, eminently corrosive. It rapidly attracts oxygen from the atmosphere, and is converted into the sulphate of barytes. The hydroguretted sul- phuret is a compound of 9.70 barytes with 4.125 bisulphuretted hydrogen; but con- taminated with sulphite and hyposulphite in unknown proportions. The dry sulphuret consists probably of 2 sulphur -j- 9-7 bary- tes. The readiest way of obtaining barytes water is to boil the solution of the sulphuret with deutoxide of copper, which seizes the sulphur, while the hydrogen flies oft', and the barytes remains dissolved. Phosphuret of barytes may be easily formed by exposing the constituents to- gether to heat in a glass tube. Their reci- procal action is so intense as to cause igni- tion. Like phosphuret of lime, it decom- poses water, and c:\uses rhe disengagement of phosphuretted hydrogen gas, which spontaneously inflames with contact of uir. When sulphur is made to act on the deu- toxide of barytes, sulphuric acid is formed, which unites to a portion of the earth into a 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 sulphu- ric acid for the carbonate, and sulphate of soda for the soluble salts of barytes. An ac- count has been given of the moit useful of these salts under the respective acids. What remains of any consequence will be found in the table of SALTS. For some in- teresting facts on the decomposition of the sulphate and carbonate, see ATTRACTION. When the object is merely to procure ba- rytes 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.* BARBADOES TAR. See PETROLEUM. BARii.LA,or BARILLOR. The term given in commerce to the impure soda imported from Spain and the Levant. It is made by burning to ashes different plants that grow on the sea-shore, chiefly of the genus sal- sola, 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. See SODA. BAROLITE. Carbonate of barytes. * B ARRAS. The resinous incrustation on the wounds made in fir trees. It is also called galipot.* BARYTES. See BARIUM. * BASALT. Occurs in amorphous mas. ses, 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 grav. 3. Melts into a black glass. It is fotinc in beds and veins in granite and mica slate the old red sandstone, limestone, and coa formations. It is distributed over the whole world; but nowhere is met with in greate; variety than in Scotland. The German basal is supposed to be a watery deposite; anc that of France to be of volcanic origin.* The most remarkable is the columnar ba BAS BAT suites, which form immense masses, com- posed of columns thirty, forty, or more feet in height, and of enormous thickness. Nay, those at Fairhead are two hundred and fif- ty feet high. These constitute some of the most astonishing scenes in nature, for the immensity and regularity 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 co- lumns, and projecting into the sea, upon a descent for several hundred feet. These co- lumns are, for the most part, hexagonal, and fit very accurately together; but most fre- quently not adherent to each other, though water cannot penetrate between them. And the basaltic appearances on the Hebrides Islands on the coast of Scotland, as de- scribed by Sir Joseph Banks, who visited them in 1772, are upon a scale very strik- ing for their vastness and variety. An extensive field of inquiry is here offer- ed to the geological philosopher, in his at- tempts 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 purposes this andother substan- ces may be applied. Bergmann found that the component parts of various specimens of basaltes were, at a medium 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 amor- phous basaltes, known by the name of row- ley rag, the ferrilite of Kirwan, of the sped- , fie 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 compo- nent parts: silex 48, alumina 16, oxide of iron 16, lime 9, soda 4, muriatic acid 1, wa- ter and volatile parts 5. Klaproth gives for the analysis of the prismatic basaltes of Ha- senberg: 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 ex- tremely minute proportion. * Sir James Hall and Mr. Gregory Watt have both proved, by admirably conducted experiments, that basalt when fused into a perfect glass will resume the stony struc- ture by slow cooling; and hence have endea- voured to show, that the earthy structure affords no argument against the igneous formation of basalt in the terrestrial globe.* Basraltes, when calcined and pulverized, is said to be a good substitute for puzzolana in the composition of mortar, giving it the property of hardening under water. Wine bottles have likewise been manufactured with it,- but there appears to be some nicety requisite in the management to ensure suc- cess. Mr. Castelveil, who heated his furnace with wood, added soda to the basaltes to render it more fusible; while Mr. Giral, who used pit coal, found it necessary to mix with his basaltes a very refractory sand. The best mode probably would be to choose basaltes of a close fine grain and uniform texture, and to employ it alone, taking care to regu- late the heat properly; for if this be carried too high, it will drop from the iron almost like water. * BASALTIC HORNBLENDE. It usually 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. Scrat- ches 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 Ar- thur's Seat, in that of Fifeshire, and in the Isles of Mull, Canna, Kigg, and Sfcy. 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 usu- ally applied to alkalis, earths, and metallic oxides, in their relations to the acids and salts. It is sometimes also applied to the particular constituents of an acid or oxide, on the supposition that the substance com- bined with the oxygen, &.c. is the basis of the compound to which it owes its particu- lar qualities. This notion seems unphiloso- phical, as these qualities depend as much on the state of combination as on the nature of the constituent.* BATH. The heat communicated from bodies in combustion must necessarily vary according to circumstances; and this varia- tion not only influences the results of opera- tions, but in many instances endangers the vessels, especially if they be made of glass. Among the several methods of obviating this inconvenience, 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 Ma- riae by the elder chemists. A bath of steam may, in some instances, be found preferable to the water bath. Some chemists have pro- posed baths of melted lead, of tin, and of other fusible substances. These may per- haps be found advantageous in a few pecu- liar operations, in which the intelligent ope- 23 BEE BEE rator must indeed be left to his own sa- gacity. * A considerably greater heat may be given to the water bath by dissolving vari- ous salts in it. Tims a saturated solution of common salt boils at 225.3, or 13.3 Fahr. above the boiling point of water. By using solution of muriate of lime, a bath of any temperature from 212 to 252 may be con- veniently obtained.* BDELLIUM. A gum resin, supposed^) 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. gruv. is 1.371. Alcohol dissolves about three-fifths of bdellium, leaving a mixture of gum and cerasin. Its constituents, accord- ing to Pelletier, are 59 resin, 9-2 gum, 30.6 cerasin, 1.2 volatile oil and loss.* * BEAN. The seed of the vicia faba, a small esculent bean, which becomes black as it ripens, has been analyzed by Einholf. He found 3840 parts to consist of 600 vo- latile matter, 386 skins, 610 fibrous starchy matter, 1312 starch, 417 vegeto-animal mat- ter, 31 albumen, 136 extractive, soluble in alcohol, 177 gummy matter, 37 earthy phosphate, 133^ loss. Fourcroy and Vau- quelin found its incinerated ashes to contain the phosphates of lime, magnesia, potash, and iron, with uncombined potash. They found no sugar in this bean. Kidney beans, the seeds of the phaseolus -vnlgans, yielded to Einholf 288 skins, 425 fibrous starchy matter, 1380 starch, 799 vegeto-animal mat- ter, not quite free from starch, 131 extrac- tive, 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 usu- ally 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 color. 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;f after which it is again made into J- The time varies very much with the weather, and is never so short as two days. 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 ren- dered dry and crisp. This is malt; and its qualities diifer according as it is more or less soaked, drained, germinated, dried, and baked. In this, as in other manufactories, the intelligent operators often make a mys- tery of their processes from views of pro- fit; 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, becomes one-fifth lighter, or 20 per cent; 12 of which are owing to kiln drying, 1.5 are carried off by the steep-water, 3 dis- sipated 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 black- ness, 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 opera- tion, of the heat applied, on the principles that are developed in the grain during the process of malting, materially alters the quality of the beer, especially with regard The perfection of the process is judged of, by the length of the roots and the germ; of the latter especially. When this has passed two-thirds of the length of the grain, it is time to check the vegetation. Heaping it up is unnecessary. If allowed to lie in heaps so long as to heat much, the malt would be injured. The drying cannot be well effected by heat in a close vessel. A current of dry air is the desi- deratum. I have seen malt made by dry air at the heat of 90 degrees. Our summer sun would answer. Greater heat gives more colour and stronger flavour, but less strength to the wort. Neither Indian corn nor rice are improved by malting, for the purpose of fermentation. Those grains only are improved by it, which have the germ to pass internally from one end to the other before coming out. One-third raw Indian corn meal, ground up with two- thirds malt, gives more strength than all malt. BEE BEE to the properties of becoming fit for drink- ing 1 and growing- fine. Beer is made from maltpreviously 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 tem- perature of the water in this operation, cal- led Mashing, must not be equal to boiling; for, in that case, the malt would be convert- ed into a paste, from which the impregna- ted water could not be separated. This is called Setting.f 1 After the infusion has re- mained for some time upon the malt, it is drawn off, and is then distinguished by the name of Sweet Wort. By one or more sub- sequent 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 gives it an aromatic bitter taste, and is supposedf2 to render it less liable to be spoiled in keep- ing; after which it is cooled in shallow vessels, and suffered to ferment,|3 with the fl The temperature should never be above 180 degrees of Fahrenheit. f 2 It is well known, that other things be- ing equal, the liquor keeps in proportion to the quantity of hops. Fresh beer may have from a pound to a pound and a half to a barrel of 32 gallons. June beer, two pounds and a half: beer for the month of August, three pounds; and for a second summer, three and an half. For India voy- ages, four pounds. f3 It ought not to ferment in shallow ves- sels, but in vessels of a cubical or deep cylindrical form. The fermentation should be commenced not lower than fifty-eight nor higher than sixty-six F. The smaller the fermenting tun and the colder the wea- ther, the warmer the wort should be, and vice versa. The fall of the head resulting from the loss of the viscidity, which ena- bles it to confine the carbonic acid, is the most obvious mark to determine when the fermentation should stop. The hydrome- ter or saccharometer affords a better mean of judging, since the same degree of at- tenuation takes place in all infusions over a certain strength, or 22 Ibs. to the London barrel, according to instruments made in that city. From 15 to 17 pounds to the bar- rel of diminution will generally be observ- ed. The fermentation is then to be stop- ped, by allowing the liquor to run into smaller vessels of about sixty gallons, and in these it becomes depurated by the yeast, which, evolved by the fermentation, entan- gles the carbonic acid, and is brought to the top of the beer by it, so as to roll out at the bung: this is called cleansing. addition of a proper quantity of yeast. The fermented liquor is beer; and differs great- ly in its quality, according to the nature of the grain, the malting, the mashing, the quantity, and kind of the hops and the yeast, the purity or admixtures of the water made use of, the temperature and vicissitudes of the weather, &c. Beside the various qualities of malt li- quors of a similar kind, there are certain leading features by which they are distin- guished, and classed under different names, and to produce which, different modes of management must be pursued. The princi- pal 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 se- parated by boiling the wort longer than for ale, and carrying the fermentation farther, so as to convert the saccharine matter into alcohol. A^e is of a more sirupy consistence, and sweeter taste; more of the mucilage be- ing retained in it, and the fermentation not having been carried so far as to decompose all the sugar .f Small beer, as its name im- plies, is a weaker liquor; and is made, either 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 originally from very high dried malt; but it is said, that its peculiar flavour can- not be imparted by malt and hops alone. *Mr. Brande obtained the folio wing quan- tities of alcohol from 100 parts of different species of beers. Burton ale, 8.88, Edin- burgh ale, 6.2, Dorchester ale, 5.56; the average being = 6.87. Brown stout, 6.8, London porter (average) 4.2, London small beer, (average) 1.28.* As long ago as the reign of Queen Anne, brewers were forbid to mix sugar, honey, Guinea pepper, essentia bina, cocculus in- dicus, or any other unwholesome ingredi- ent, in beer, under a certain penalty; from which we may infer, that such at least was the practice of some; and writers, who pro- fess to discuss the secrets of the trade, mention most of these and some other arti- cles 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 keep- ing, before hops were introduced into this f There is no essential difference be- tween the mode of brewing ale and beer. The colour and flavour of the malt is the principal ground of distinction. Keep- ing ale is boiled longer than fresh beer. The more sirupy consistence is in conse- quence of more malt being used. BEE BEN country; but now are prohibited to be used in beer made for sale. * By the present law of this country, nothing is allowed to enter into the com- position of beer, except malt and hops. Quassia and wormwood are often fraudu- lently introduced; both of which are ea- sily discoverable by their nauseous bitter taste. They form a beer which does not preserve so well as hop beer. Sulphate of iron, alum, and salt, are often added by the publicans, under the name of beer-hfdd- ing> 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. Cap- sicum, grains of paradise, ginger root, co- riander seed, and orange peel, are also em- ployed to give pungency and flavour to weak or bad beer. The following is a list of some of the unlawful substances seized at different breweries, and brewers' drug- gists' laboratories, in London, as copied from the minutes of the committee of the House of Commons. Coculus indicus, mul- tum, (an extract of the cocculus), colour- ing, honey, hartshorn shavings, Spanish juice, orange powder, ginger, grains of paradise, quassia, liquorice, caraway seeds, copperas, capsicum, mixed drugs. Sulphu- ric 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 opium, tobacco, nux vomica, and extract of poppies, have likewise been used to adulterate beer. For an account of the poisonous qualities of the cocculus in- dicus, see PICROTOXIA, and for those of nux vomica, see STRYCHNIA. By evapo- rating a portion of beer to dryness, and ig- niting the residuum with chlorate of pot- ash, the iron of the copperas will be pro- cured in an insoluble oxide. Muriate of barytes will throw down an abundant pre- cipitate from beer contaminated with sul- phuric acid or copperas^ which precipitate may be collected, dried, and ignited. It Will be insoluble in nitric acid.* Beer appears to have been of ancient vse, as Tacitus mentions it among the Germans, and has been usually supposed to have been peculiar to the northern na- tions: but the ancient Egyptians, whose country was not adapted to the culture of the grape, had also contrived this substi- tute 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. *BELLMETAL. See COPPER.* * BELLMETAL ORE. See ORES OF TIN.* BEN (OIL OF). This is obtained from the ben nut, by simple pressure. It is re- markable for its not growing rancid in keep- ing, or at least not until it has stood for a number of years; and on this account it is used in extracting the aromatic principle of such odoriferous 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 in- cisions, in the form of a thick white bal- sam. If collected as soon as it has grown somewhat solid, it proves internally white like almond, and hence it is called Ben- zoe 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 brit- tle, and yields an agreeable smell when rubbed or warmed. When chewed, it im- presses 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 gra- vity is 1.092. The white opaque fluid thus obtained lias been called Lac Virginale; and is still sold, with other fragrant additions, by per- fumers, as a cosmetic. Boiling water sepa- rates the peculiar acid of benzoin. The products Mr. Brande obtained by distillation were, from a hundred grains, ben zoic acid 9 grains, acidulated watev 5.5, butyraceous and empyreumatic oil 60, brittle coal 22, and a mixture of carburet- ted hydrogen and carbonic acid gas, com- puted at 3.5. On treating the empyreuma- tic oil with water, however, 5 grains more of acid were extracted, making 14 in the whole. * From 1500 grains of benzoin, Bucholz $ Consult the Philosophical Transactions, vol. Ixxvii. page 307, for a botanical de- scription and drawing of the tree, by Dry- ander. BE/, BIL obtained 1250 of resin, 187 benzole 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 im- purities. Ether, sulphuric and acetic acids, dis- solve benzoin; so do solutions of potash and soda. Nitric acid acts violently on it, and a portion of artificial tannin is formed. Am inonia dissolves it sparingly.* * BERGMANNITE. A massive mineral of a greenish, greyish-white, or reddish co- lour. Lustre intermediate between pearly and resinous. Fracture fibrous, passing into line grained, uneven. Slightly translucent on the edges. Scratches felspar. Fuses into a transparent glass, or a semi-transparent ena- mel. It is found at Frederickswarn in Nor- way, in quartz and in felspar.* * BERYL. This precious mineralj is most commonly green, of various shades, passing into honey-yellow, and sky-blue. It is crys- tallized in hexahedral prisms deeply striat- ed longitudinally, or in 6 or 12 sided prisms, terminated by a 6 sided pyramid, whose summit is replaced. It is harder than the emerald, but more readily yields to cleav- age. Its sp. grav. is 2.7. Its lustre is vitre- ous. It is transparent, and sometimes only translucent. It consists by Vauquelin of 68 silica, 15 alumina, 14 glucina, 1 oxide of iron, 2 lime. Berzelius found in it a truce of oxide of tantalum. It occurs in veins tra- versing granite in Daouria; in the Altaic chain in Siberia; near Limoges in France; in Saxony; Brazil; at Kinloch liaimoch, and Cairngorm, Aberdeenshire, Scotland; above Dundrum, in the county of Dublin, and near Cronebane, county of Wicklow, in Ireland. It differs from emerald in hardness and co- lour. It has been called aqua marine, and greenish-yellow emerald. It is electric by friction and not by heat.* * BEZ.OAR. 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 ex- tended to ail concretions found in animals. These are of eight kinds, according to Fourcroy, Vauquelin, and Berthollet. 1. Su- perphosphate of lime, which forms concre- tions in the intestines of many mammalia. 2. Phosphate of magnesia, semi-transparent and yellowish, and of sp. grav. .160. 3. Phosphate of ammonia and magnesia. A concretion of a grey or brown colour, com- posed of radiations from a centre. It is found in the intestines of herbiverous animals, the elephant, horse, &c. 4. Biliary, colour red- j- Beryl is not always precious, and even when transparent, as in the form of aqua Tsarina, has little value. dish-brown, found frequently in the intes- tines and gall bladder of oxen, and used by painters for an orange-yellow pigment. It is inspissated bile 5. Resinous. The oriental bezoars, procured from unknown animals, belongto tbis class of concretions. They con- sist of concentric layers, are fusible, com- bustible, smooth, soft, and finely polished. They are composed of bile and resin. 6. Fungous, consisting of pieces of the boletus igniarius, swallowed by the animal. 7. Hairy. 8. Ligniform. Three bezoars sent to Bona- parte by the king of Persia, were found by Berthollet to be nothing but woody fibre agglomerated.* BlHYDROGURET OF CARBON. See CARBURETTED HYDROGEN. BlHYDROGURET OF PHOSPHORUS. See PHOSPHURETTED HYDROGEN. *BILDSTEIN, AGALMATOLITE, or Fi- GURESTONE. A massive mineral, with sometimes an imperfectly slaty structure. Colour gray, brown, flesh red, and some- times spotted, or with blue veins. It is trans- lucent 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 Vau- quelin. 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. Brongniart calls it steatite pagodite, from its coining from China cut into grotesque figures. It wants the magnesia, which is a constant ingredient of steatites. It is found at Naygag in Transyl- vania, and Glyder-bach 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, common to a great number of animals, the peculiar secretion of their liver. It is the prevailing- opinion of physiologists, that the bile is separated from the venous, and not like the other secretions, from the arterial blood. The veins which receive the blood distributed to the abdominal viscera, unite into a large trunk called the vena portce, which divides into two branches, that pene- trate into the liver, and divide into innumer- able ramifications. The last of these termi- nate 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 ductns choledochus, when the animal has no gall bladder; but w r hen it has one, as more frequently hap- pens, the bile flows back into it by the cys- tic duct, and remaining there for a longeF or shorter time, experiences remarkable al- terations. Its principal use seems to be, to promote the duodenal digestion, in concert with the pancreatic juice. Boerhaave, by an extravagant error, re- BIL BIR garded the bile as one of the most putresci- ble fluids; and hence originated many hypo- thetical and absurd theories on diseases and their treatment. We shall follow the ar- rangement of M. Thenard, in a subject which owes to him its chief illustration. 1. 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 support- able. Its smell, though feeble, is easy to recognize, 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 dis- turbed with a yellow matter, from which it may be easily separated by water; its con- sistence 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 composed 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 phosphate of lime, and a trace of oxide of iron. When distilled to dry ness, it leaves from l-8th to 8-9th of solid matter, which, urged with a higher heat, is resolved into the usual ig- neous products of animal analysis; only with more oil and less carbonate of ammonia. Exposed for some time in an open ves- sel, 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 exhales is not insupportable, but in some cases has been thought to re- semble that of musk. Water and alcohol combine in all proportions with bile. When a very little acid is poured into bile, it be- comes slightly turbid, and reddens litmus; when more is added, the precipitate aug- ments, particularly if sulphuric acid be em- ployed. It is formed of a yellow animal mat- ter, 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 phospho- ric acids of the bile. The solution of the sub- acetate precipitates not only these bodies, but also the picromel and the muriatic acid, all combined with the oxide of lead. The a- cetic acid remains in the liquid united to the soda. The greater number of fatty substan- ces are capable of being dissolved by bile. This property, which made it be considered a soap, is owing to the soda, and to the tri- ple compound of soda, resin, and picromel Scourers sometimes prefer it to soap, for cleansing woollen. The bile of the calf, the dog, and the sheep, is similar to that of the ox. The bile of the sow contains no picro- mel. It is merely a soda-resinous soap. Hu- man bile is peculiar. It varies in colour, sometimes being green, generally yellow- ish-brown, occasionally almost colourless. Its taste is not very bitter. In the gall blad- der it is seldom limpid, containing often, like that of the ox, a certain quantity 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 dry- ness, there results a brown extract, equal in weight to 1-1 1th of the bile. By calcina- tion we obtain the same salts as from ox bile. All the acids decompose human bile, and occasion an abundant precipitate of albu- men and resin, which are easily separable by alcohol. One part of nitric acid, 'sp. grav. 1.210, saturates 100 of bile. On pour- ing into it a solution of sugar of lead, it is changed into a liquid of a light yellow co- lour, in which no picromel can be found, and which contains only acetate of soda, and some traces of animal matter. Human bile appears hence to be formed, by The- nard, in 1100 parts; of 1000 water; from 2 to 10 yellow insoluble matter; 42 albumen; 41 resin; .5.6 soda: and 45 phosphates of so- da and lime, sulphate of soda, muriate of soda and oxide of iron. But by Berzelius, 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 phos- phate of lime.* BIRDLIME. The best birdlime is made of the middle bark of the holly, boiled se- ven or eight hours in water, till it is soft and tender; then laid in heaps in pits in the ground and covered witli 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 mortar to a paste, washed in river water, and kneaded, till it is freed from extraneous matters. In this state it is left four or five days in earthen vessels, to ferment and purify itself, when it is fit for use. It may likewise be obtained from the misleto, the viburnum lantana, young shoots of elder, and other vegetable sub- stances. It is sometimes adulterated with turpen- tine, oil, vinegar, and other matters. Good birdlime is of a greenish colour and sour flavour; gluey, stringy, and tena- cious; and in smell resembling linseed oil. By exposure to the air it becomes dry and brittle, so that it may be powdered; but its viscidity is restored "by wetting it. It red- BIS BIS dens tincture of litmus. Exposed to a gen- tie heat it liquefies slightly, swells in bub- bles, becomes grumous, emits a smell re- sembling 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.f It is somewhat harder than lead, and is scarely, if at all, mallea- ble; being easily broken, and even reduced to powder, by the hammer. The internal face, or place of fracture, exhibits large shining plates, disposed in a variety of po- sitions; thin pieces are considerably sono- rous. 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 -f- 11.275 oxygen, whence its prime equiva- lent will be 9.87, and that of the metal it- self 8.87. The specific gravity of the me- tal is 9.85.* Bismuth, urged by a strong heat in a closed vessel, sublimes entire, and crystal- lizes very distinctly when gradually cooled The sulphuric acid has a slight action upon bismuth, 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 de- liquescent salt in the form of small needles. The nitric acid dissolves bismuth with the greatest rapidity and violence; at the same time that much heat is extricated, and a large quantity of nitric oxide escapes. The solution, when saturated, affords crys- tals 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 wa- ter, 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 f It is more properly tin or silver-white -with a blush of red, 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 pro- perties of lead and bismuth, that the oxide ot this metal may be attended with effects similar to those which the oxides of lead are known to produce. If a small portion of muriatic acid be mixed with the nitric, and the precipitated oxide be washed with but a small quantity of cold water, it will ap- pear in minute scales of a pearly lustre, constituting the pearl potuder of perfumers. These paints are liable to be turned black by sulphuretted hydrogen gas. The muriatic acid does not readily act upon bismuth. * When bismuth is exposed to chlorine gas it takes fire, and is converted into a chloride, which, formerly prepared by heat- ing the metal with corrosive sublimate, was called butter of bismuth. The chloride is of a grayish-white colour, a granular tex- ture, 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 4.45 chlorine, -f- b.87 bismuth, = 13.32. When iodine and bismuth are heated together, 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 se- cond is a bisulphuret.* This metal unites with most metallic substances, and renders them in general more fusible. When calcined with the im- perfect 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 pewter, in the fabrication of printers' tvpes, and in various other metallic mixtures. With an equal weight of lead, it forms a brilliant white alloy, much harder than lead, and more malleable than bismuth, though not ductile; and if the proportion of lead be increased, it is rendered still more malleable. Eight parts of bismuth, five of lead, and three of tin, constitute BIT BIT tfoe fusible metal, sometimes called New- ton'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 plumbers' solder. It forms the basis of a sympathetic ink. The oxide of bismuth, precipitated by potash from ni- tric acid, has been recommended in spas- modic 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 de- fend it from oxidation. The same process may be imitated in the small way, in the examination of the ores of this metal; no- thing more being necessary, than to expose it to a moderate heat in a crucible, with a quantity of reducing flux; taking care, at the same time, to perform the operation as speedily as possible, that the bismuth may be neither oxidized nor volatilized. 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. * BITTER PRINCIPLE, of which there are several varieties. When nitric acid is digested on silk, in- digo, or white willow, a substance of a deep yellow colour, and an intensely bitter taste, is formed. It dyes a permanent yel- low. It crystallizes, in oblong plates, and saturates alkalis, like an acid, producing crystallizable salts. That with potash, is in yellow prisms. They are bitter, per- manent in the air, and less soluble than the insulated bitter principle. On hot char- coal they deflagrate. When struck smart- ly on an anvil, they detonate with much violence, and with emission of a purple light. Ammonia deepens the colour of the bitter principle solution, and forms a salt in yellow spiculae. It unites also with the alkaline earths and metallic oxides. M. Chevreul considers it a compound of nitric acid, with a peculiar substance of an oily nature. Quassia, cocculus Indicus, daphne Alpina, coffee, squills, colocynth, and bry- ony, as well as many other medicinal plants, yield bitter principles, peculiarly modified.* BITTERN. The mother waterwhich re- mains after the crystallization of common- salt in sea water, or the water of salt springs. It abounds with sulphate and muriate of magnesia, to which its bitterness is owing. See WATER (SEA). * BlTTERSPAR, Or RHOMBSPAR. ThJ9 mineral crystallizes in rhomboids, which were confounded with those of calcareous spar, till Dr. Wollaston applied his admi- rable reflecting goniometer, and proved the peculiarity of the angles in bitterspar, which are 106 15', and 73 45'. Its colour is grayish or yellow, with a somewhat pear- ly lustre. It is brittle, semi-transparent, 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 carbo- nate of magnesia, and 2 oxide of manga- nese. It is usually imbedded in serpentine, chlorite or steatite; and is found in the Ty- rol, Salzburg, and Dauphiny. In Scotland, on the borders of Loch Lomond in the chlo- rite slate, and near Newton-Stewart in Gal- loway; as also in the Isle of Mann. It bears the same relation to dolomite and magne- sian limestone, that calcareous spar does to common limestone.* BITUMEN. This term includes a consi- derable 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, yellow, or black clays in Persia and Media. This is highly in- flammable, and is decomposed by distilla- tion. It dissolves resins, and the essential 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 spe- cific gravity being 0.708. 2. Petroleum, which is a yellow, reddish, brown, green- ish, or blackish oil, found dropping from rocks, or issuing from the earth, in the duchy of Modena, and in various other parts of Europe and Asia. This likewise is insoluble in alcohol, and seems to consist of naphtha, thickened by exposure to the atmosphere. It contains a portion of the succinic acid. 3. Barbadoes tar, which is a viscid, brown, or black inflammable sub- stance, insoluble in alcohol, and contain- ing the succinic acid. This appears to be the mineral oil in its third state of altera- tion. The solid are, 1. Asphaltum, mineral pitch, of which there are three varieties: the cohesive; the semi-compact, maltha; the compact, or asphaltum. These are smooth, more or less hard or brittle, in- flammable 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 sub- stance of the consistence of tallow, and as greasy, although more brittle. It was found in the sea on the coasts of Finland, in the BLA BLE year 1736; and is also met with in some rocky parts of Persia. It is nearly 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 caoutchouc, of which there are two vari- eties. Beside these, there are other bitumi- nous substances, as jet and amber, which approach the harder bitumens in their na- ture; and all the varieties of pit-coal, and the bituminous schistus, or shale, which, contain more or less of bitumen in their composition. See the different kinds of bi- uimcn and bituminous substances, in their respective places in the order of the alpha- bet. | There are no two substances more op- posite in their habitudes with caloric, than carbon and hydrogen. The last is, of all ponderable substances, the most volatile; and, per se, probably the most incondensi- ble. Charcoal, on the other hand, cannot even be fused, much less volatilized, per se. It has, perhaps, of all substances, the least disposition to combine with caloric. Hence, in the combinations of hydrogen and carbon, we find a gradation of proper- ties from substances, fixed like anthracite, to naphtha, or inflammable matter, almost as volatile as air, accordingly as the carbon or hydrogen predominates in the com- pound. The distillation of rosin yields, besides carburetted hydrogen, a species of petro- leum; and this by rectification yields an essential oil, like oil of tar, and afterwards some heavier and less volatile products, some of which though white at first turn black by keeping. In like manner, mineral bitumens and bituminous coals yield petroleum, and vol- atile oil. A quantity of acetic acid comes over in combination with the petroleum of rosin, and is retained till the heat is con- siderable. It is then evolved with explosive violence.f * BITUMINOUS LIMESTONE is of a la- mellar structure; susceptible of polishing; emits an unpleasant smell when rubbed, and has a brown or black colour. Heat con- verts it into quicklime. It contains 8.8 alu- mina; 0.6 silica; 0.6 bitumen; and 89.75 car- bonate 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 fingers, and is meagre to the touch. It contains about 64 silica, 11 alumina, 11 car- bon, with a little iron and water. It is found in primitive mountains, and also sometimes VOL. I. near coal formations. It occurs in CaernaiN vonshire, 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 un- doubtedly resinous. Hence, M. Baume pro- posed the following process, as the best mode of bleaching it. On six pounds of yel- low raw silk, disposed in an earthen pot, 48 pounds of alcohol, sp. gr. 0.867, mixed with 12 oz. muriatic 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 drain* ed, and washed with alcohol. A second in.? fusion with the above acidulated alcohol 19 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 lime, and distilling. M. Baume" says, that silk may thus be made to rival or surpass in white- ness and lustre, the finest specimens from Nankin. But the ordinary method of bleach- ing silk is the following:* 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 dissolved gopd Genoa or Toulon soap. After the silk has boiled two or three hours in that water, the bag being frequent- ly turned, it is taken out to be beaten, and is then washed in cold water. When it has been thus thorougly 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 se. cond water, they wring it hard with a wood- en peg, to press out all the water and soapj after which they shake it to untwist it, an4 separate the threads. Then they suspend it in a kind of stove constructed for that pur- pose, where they burn sulphur; the vapour of which gives the last degree of white- ness 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 sul- phur. Bleaching ivith soap and water.* After thft stuffs are taken out of the fuller's niijl, 24 BLE BLE 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 white- ning which the fuller's mill had only be- gun. When they have been sufficiently 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. JBleaching with sulphur. They J>egin with washing and cleansing the stuffs tho- roughly 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 sul- phur; 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 Bleach- ing of Paris, because they use this method in that city more than any where else. * The colouring matter of linen and cot- ton is also probably resinous; at least the experiments of Mr. Kirwan on alkaline lix- ivia saturated with the dark colouring mat- ter, lead to that conclusion. By neutralizing the alkali with dilute muriatic acid, a pre- cipitate resembling lac was obtained, solu- ble in alcohol, in solutions of alkalis, and alkaline sulphurets. The first step towards freeing vegetable yarn or cloth from their native colour, is fermentation. The raw goods are put into a large wooden tub, with a quantity of used alkaline lixivium, in an acescent state, heat- ed to about the hundredth degree of Fahr. It would be better to use some uncolouied fermentable matter, such as soured bran or potato 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 quali- ty of the stuffs, the fermentation ceases, when the goods are to be immediately with- drawn and washed. Much advantage may be derived by the skilful bleacher, from con- ducting the acetous fermentation complete- ly to a close, without incurring the risk of injuring the fibre, by the putrefactive fer- mentation. The goods are next exposed to the ac- tion of hot alkaline lixivia, by bucking or boiling, or both. The former operation con- sists in pouring boiling hot ley on the cloth placed in a tub; after a short time drawing off the cool liquid below, and replacing it above, by hot lixivium. The most conveni- ent arrangement of apparatus is the follow- ing: 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 upwards pressure of steam. From the side of the iron boiler, a little above its bottom, a pipe issues, which, turning at right angles up. wards, 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 off a 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 immedi- ately within the lid, is a metallic circular disc. The boiler being charged with lixiv- ium, 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 machinery. Thus, the lixivium in its progressively heating state, is made to circulate conti- nually 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 horizontal one in an uninterrupt- ed stream. The valve at the bottom of the tub, yielding to the accumulated weight of the liquid, opens from time to time, and re- places the lixivium in the boiler. This most ingenious self-acting appara- tus, was invented by Mr. John Laurie of Glasgow; and a representation of it accom- panies Mr. Ramsay's excellent article, Bleaching, in the Edinburgh Encyclopaedia. By its means, labour is spared, the negli- gence 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 incompatible with good bleaching. When the ley seems to be impregnated with co- louring matter, 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 rota- tory wooden wheel with hollow compart- ments, called the dash wheel. The strength of the alkaline lixivium is varied by diffe- rent bleachers. A solution of potash, ren- dered caustic by lime, of the specific gra- vity 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 alkaline power. The routine of operations may be conveniently presented in a tabular form. A parcel of goods consists of 360 pieces BLE BLE 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 sub- jected to the acetous fermentation, as above described. They then undergo the follow- ing 1 operations: 1. Bucked with 60 Ibs. pearl ashes, washed and exposed on the field. 2. do. with 80 Ibs. do. do. do. 3. do. 90 potashes do. do. 4. do. 80 do. do. do. 5. do. 80 do. do. do. 6. do. 50 do. do. do. 7. do. 70 do. do. do. 8. do. 70 do. do. do. 9. Soured one night in dilute sulphuric acid. 10. Bucked with 50 Ibs. pearl ashes, washed and exposed. 11. Immersed in the oxymuriate of pot- ash for 12 hours. 12. Boiled with 30 Ibs. pearl ashes, washed and exposed. 13. do. 30 do. do. do. 13. 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 pe- riod 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 re- turned to be boiled and steeped in the oxy- muriate 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 thoroughly 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, thatmany enlightened bleachers have found it advantageous to apply the souring at a more early period, as well as the oxy muri- atic solution. According to Dr. Stephen- son, in his elaborate paper on the linen and hempen manufactures, published by the Belfast Literary Society, 10 noggins, 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 Es- says, 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 sci- entific calico printer in Scotland makes his sours to have the specific gravity 1.0254 at 110 of Fahrenheit; which dilute acid con- tains 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 tem- perature. Most bleachers use the strongest alkaline lixiviums at first, and the weaker afterwards. As to the strength of the oxy- muriatic steeps, as the bleacher terms them, it is difficult to give certain 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 ca- licoes have been singed, steeped, and squeezed, they are boiled four successive times, for 10 or 12 hours each, in a solu- tion of caustic potash of a specific gravity from 1.0127 to 1.0156, and washed tho- roughly between each boiling. " They are then immersed in a solution of the oxymu- riate of potash, originally of the strength of 1.0625, and afterwards reduced with 24 times its measure of water. In this pre- paration they are suffered to remain 12 hours." Dr. Stephenson says, that, for coarse linens, the steep is made by dissolv- ing 1 Ib. of oxymuriate 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 oxymu- riate of lime is always more or less mixed with common muriate of lime, or chloride of calcium, a little of which has a great ef- fect on the hydrometric indications. The period of immersion is 10 or 12 hours. Many bleachers employ gentle and long continued boiling without bucking 1 . The operation of souring was long ago effected by butter milk, but it is more safely and advantageously performed by the dilute sulphuric acid uniformly combined with the water by much agitation. 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 pre- pared and properly applied, it will not in- jure the most delicate 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 employment. The muriate of lime solution resulting 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 acci- dent; and the process of souring,' which BLE BLE follows most commonly the oxymuriatic ateep, 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 oxy muriate of lime. They require, he says, oxymuriate of potash. I believe this to be a mistake. Test liquors made by dissolving indigo in sulphuric acid, and then diluting the sulphate with water, or with infusion of cochineal, are employed to measure the blanching power of the oxy- muriatic or chloridic solutions. But they are all more or less uncertain, from the changeableness of these colouring matters. I have met with indigo of apparently ex- cellent 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 colour- ed liquors, however, though they give no absolute measure of chlorine, afford useful means of comparison to the bleacher. Some writers have recommended lime fend sulphuret of lime as detergent substan- fces instead of alkali; but 1 believe no prac- tical bleacher of respectability would trust to them. Lime should always be employed, however, to make the alkalis caustic; in which state their detergent powers are greatly increased. 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 solu- tion of chloride of lime or potash. The boil- ing 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 se- ries of operations 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 dress- ing is well removed by cold water, they are gently boiled with soap, washed, and immersed in a moderately strong solution of oxymuriate of potash. This process is repeated till the white parttfof the cloth are sufficiently pure. They an then soured in dilute sulphuric acid. If these operations be well conducted, the colours, instead of being impaired, will be greatly improved, having acquired a delicacy of tint which ho other process can impart. After immersing cloth or yarn in alka- line 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 Glasgow. " In fermenting muslin goods, M r e sur- round 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, in 360 gallons of water, and allow them to boi! for 6 hours; then wash them, and boil them again, with 5 Ibs. of ashes, and 2 Ibs. of soft soap, in the same quantity of water, and al- low them to boil 3 hours; then wash them with water, and immerse them into the so- lution of oxymuriate of lime, at 5 on the test tube, and allow them to remain from 6 to 12 hours; next wash them, and immerse them into diluted sulphuric acid at the spe- cific gravity of 3 on Twaddle's hydrome- ter = 1.0175, and allow them to remain an hour. They are now well washed, and boil- ed with 2jt Ibs. of ashes, and 2 Ibs. 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 al- lowed to remain for 6 hours. They are again washed and immersed into diluted sul- phuric 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 sul- phuric 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 fer- menting, the same weight of it is employed as of ashes. The goods are allowed to boil in it for 15 minutes, but not longer, other- wise the lime will injure the fabric." The alkali may be recovered from the brown lixivia, by evaporating them to dry- ness and gentle ignition of the residuum. But, in most situations, the expense of fuel would exceed the value of the recovered alkuli. A simpler mode is to boil the foul lixivium with quicklime, and a little pipe- clay and bullock's blood. After skimming* and subsidence, a tolerably pure ley is ob- tained.* Under the head of chlorine, we have de- scribed the preparation of this article; and the chief circumstances respecting it to be noticed 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 dis- tillation may be performed in a large leaden alembic, ,, Plate I. fig. 1. supported by an iron trevetj^ in an iron boiler e. This is heated by a furnace 6, of which o is the BLE BLO ashhole, c the place for introducing the fuel; 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 /i, through which the sulphuric acid is to be poured in; one in the centre for the agita- tor k, made of iron coated with lead; and the third for the leaden tube I, 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 rotatory motion, as to prevent the escape of the gas. The tube /, passing through the aperture m, to the bottom of the interme- diate receiver nearly, which is two-thirds full of water, deposites there the little sul- phuric acid that may arise; while the chlo- rine gas passes through the tube n into the wooden condenser o o. The agitator />, turned by its handle t, serves to accelerate the combination of the gas with the alkali, to which the horizontal pieces g q t pro- jecting from the inside, like wise contribute. The cover of this receiver has a sloping groove r, to fit close on its edge, which is bevelled on each side; and a cock s serves to draw off the liquor. Mr. Tennent's chlo- ride of lime has nearly superseded that plan. The rags or other materials for making paper may be bleached in a similar man- ner: but it is best to reduce them first to the state of pulp, as then the acid acts more uniformly upon the whole substance. For bleaching old paper: Boil your print- ed paper for an instant in a solution of caustic soda. That from kelp maybe used. Steep it in soap-suds, and then wash it; after which it may be reduced to pulp. The soap muy be omitted without much inconvenience. For old written paper to be worked up again: Steep it in water acidu- lated with sulphuric acid, and then wash it well before it is taken to the mill. If the water he heated it will be more effectual. To bleach printed paper, without destroy- ing its texture: Steep the leaves in a caus- tic solution of soda, either hot or cold, and then in a solution of soap. Arrange them alternately between cloths, as paper- makers do thin sheets of paper when de- livered from the form, and subject them to the press. If one operation do not render them sufficiently white, it may be repeated as often as necessary. To bleach old writ^ ten paper, without destroying its texture: Steep the paper in water acidulated with sulphuric acid, either hot or cold, and then in a solution of oxygenated muriatic acid; after which immerse it in water, that none of the acid may remain behind. This paper, when pressed and dried, will be fit for use as before. BLENDE. An ore of zinc. BLOOD. The fluid which first presents itself to observation, when the parts of liv- ing animals are divided or destroyed, is the blood, which circulates with conside- rable velocity through vessels, called veins and arteries, distributed into every part of the system. Recent blood is uniformly fluid, and of a saline taste. Under the microscope, it ap- pears to be composed of a prodigious num- ber of red globules, swimming in a trans- parent fluid. After standing for a short time, its parts separate into a thick red matter, or crassamentum, and a fluid call- ed serum. If it be agitated till cold, it continues fluid; but a consistent polypous matter adheres to the stirrer, which by re- peated ablutions with water becomes white, and has a fibrous appearance; the crassa- mentum becomes white and fibrous by the same treatment. If blood be received from the vein into warm water, a similar fila- mentous matter subsides, while the other parts are dissolved. Alkalis prevent the blood from coagulating; acids, on the con- trary, accelerate that effect. In the latter case, the fluid is found to contain neutral salts, consisting of the acid itself, united with soda, which consequently must exist in the blood, probably in a disengaged state. Alcohol coagulates blood. On the water bath, blood affords an aqueous fluid, neither acid nor alkaline, but of a faint smell, and easily becoming putrid. A stronger heat gradually dries it, and at the same time reduces it to a mass of about one-eighth of its original weight * Blood usually consists of about 3 parts serum to one of cruor. The serum is of a pale greenish-yellow colour. Its specific gravity is about 1.029, while that of blood itself is 1.053. It changes sirup of violets to a green, from its containing free soda. At 156 serum coagulates, and resembles boiled white of egg. When this coagu- lated albumen is squeezed, a muddy fluid exudes, which has been called the sero- sity. According to Berzelius, 1000 parts of the scrum of bullock's blood consist of 905. water, 79.99 albumen, 6.175 lactate of soda and extractive matter, 2.565 muriates of soda and potash, 1.52 soda and animal matter, and 4.75 loss. 1000 parts of serum of human blood consist, by the same che- mist, of 905 water, 80 albumen, 6 muriates of potash and soda, 4 lactate of soda with animal matter, and 4.1 of soda, and phos- phate of soda with animal matter. There is no gelatin in serum. BLO The cruor has a specific gravity of about 1.245. By making- a stream of water flow upon it till the water runs off colourless, it is separated into insoluble fibrin, and the soluble colouring matter. A little albumen has also been found in cruor. The propor- tions of the former two, are 64 colouring- matter, and 36 fibrin in 100. To obtain the colouring- matter pure, we mix the cruor with 4 parts of oil of vitriol previously di- luted with 8 parts of water, and expose the mixture to a heat of about 160 degree? for 5 or 6 hours. Filter the liquid while hot, and wash the residue with a few ounces of hot water. Evaporate the liquid to one-half, and add ammonia, till the acid be almost, but not entirely saturated. The colouring- matter falls. Decant the supernatant liquid, filter and wash the residuum, from the whole of the sulphate of ammonia. When it is well drained, remove it with a platina blade, and dry it in a capsule. When solid, it appears of a black colour, but becomes wine-red by diffusion through water, in which, however, it is not soluble. It has neither taste nor smell. Alcohol and ether convert it into an unpleasant smell- ing- kind of adipocere. It is soluble both in alkalis and acids. It approaches to fibrin in its constitution, and contains iron in a pe- culiar state, -3- of a per cent of the oxide of which may be extracted from it by cal- cination. The incinerated colouring- matter weig-hs l-80th of the whole; and these ashes consist of 50 oxide of iron, 7.5 sub- phosphate of iron, 6 phosphate of lime, with traces of magnesia, 20 pure lime, 16.5 carbonic acid and loss; or the two latter in- gredients may be reckoned 32 carbonate of lime. Berzelius imagines that none of these bodies existed in the colouring- matter, but only their bases, iron, phosphorus, calcium, carbon, &c. and that they were formed dur- ing the incineration. From the albumen of blood, the same proportion of ashes may be obtained, but no iron. No good explanation has yet been given of the change of colour which blood un- dergoes from exposure to oxygen, and other gases. Under the exhausted receiver, carbonic acid gas is disengaged from it. The blood of the foetus is darker coloured than that of the adult; it has no fibrin, and no phosphoric acid. The buffy coat of in- flamed blood is fibrin; from which the co- louring matter has precipitated by the greater liquidity or slowness of coagula- tion produced by the disease. The serum of such blood does not yield consistent al- bumen by heat. In diabetes mellitus, when the urine, of the patient is loaded with su- gar, the serum of the blood assumes the appearance of whey, according to Drs. Rol- lo and Dobson; but Dr. Wollaston has proved that it contains no sugar.* BLO Dr. Carbonel of Barcelona has employed serum of blood on an extensive scale in painting. Mixed with powdered quicklime or slaked lime, to a proper consistence, it is easily applied on wood, to which it thus gives a coating of a stone colour, that dries quickly, without any bad smell, and resists the action of sun" and rain. The wood should be first covered with a coating of plaster; the composition must be mixed as it is used, and the serum must not be stale. It may be used too as a cement for water- pipes, and for stones for building under water. * BLOODSTONE. See CALCEDONY.* BLOW-PIPE. This simple instrument will be described under the article LABORA- TORY. * We shall here present our readers first with an abstract of Assessor Calm's late valuable treatise on the common blow-pipe, and shall afterwards give an account of Dr. Clark's very interesting experiments with the oxyhydrogen blow-pipe-* The substance to be submitted to the action of the blow-pipe must be placed on a piece of charcoal, or in a small spoon of platina, gold, or silver; or, according to Saussure, a plate of cyanite may sometimes be used. Charcoal from the pine is to be preferred, which should be well ignited and dried, that it may not crack. The sides, not the ends, of the fibres must be used, otherwise the substance to be fused spreads about, and a round bead will not be form- ed. A small hole is to be made in the char- coal, which is best done by a slip of plate iron bent longitudinally. Into this hole the sub- stance to be examined must be put in very small quantity; if a very intense heat is to be used, it should not exceed the size of half a peppercorn. The metallic spoons are used when the substance to be examined is intended to be exposed to the action of heat only, and might undergo some change by immediate contact with the charcoal. When the spoon is used, the flame of the blow-pipe should be directed to that part of it which con- tains the substance under examination, and not be immediately applied to the substance itself. The handle of the spoon may be in- serted into a piece of charcoal: and if a very intense heat is required, the bowl of the spoon may be adapted to a hole in the charcoal. Small portions may be taken up by platina forceps. Salts and volatile sub- stances are to be heated in a glass tube closed at one end, and enlarged according to circumstances, so as to form a small ma- trass. When the alteration which the substance undergoes by the mere action of heat has been observed, it will be necessary to exa- mine what further change takes place when BLO BLO when it is melted with various fluxes, and how far it is capable of reduction to the metallic state. These fluxes are, 1. Microcosmic salt; a compound of phos- phoric acid, soda, and ammonia. 2. Subcarbonate of soda, which must be free from all impurity, and especially from sulphuric acid, as this will be decomposed, and sulphuret of soda will be formed, which will dissolve the metals we wish to reduce, and produce a bead of coloured glass with substances that would otherwise give a co- lourless one. 3. Borax, which should be first freed from its water of crystallization. These are kept powdered in small phials; and when used, a sufficient quantity may be taken up by the moistened point of a knife the moisture causes the particles to cohere, and prevents their being blown away when placed on the charcoal. The flux must then be melted to a clear bead, and the substance to be examined placed upon it. It is then to be submitted to the action, first of the exterior, and afterwards of the interior flame, and the following cir- cumstances to be carefully observed: 1. Whether the substance is dissolved; and, if so, 2. Whether with or without efferves- cence, which would be occasioned by the liberation of carbonic acid, sulphurous acid, oxygen, gaseous oxide of carbon, &c. 3. The transparency and colour of the glass while cooling. 4. The same circumstances after cooling. 5. The nature of the glass formed by the exterior flame, and 6. By the interior flame. 7. The various relations to each of the fluxes. It must be observed that soda will not form a bead on charcoal, but with a cer- tain degree of heat will be absorbed. When, therefore, a substance is to be fused with soda, this flux must be added in very small quantities, and a very moderate heat used at first, by which means a combination will take place, and the soda will not be ab- sorbed. If too large a quantity of soda has been added at first, and it has consequently been absorbed, a more intense heat will cause it to return to the surface of the charcoal, and it will then enter into com- bination. Some minerals combine readily with only very small portions of soda, biit melt with difficulty if more be added, and are absolutely infusible with a larger quantity: and when the substance has no affinity for this flux, it is absorbed by the charcoal, and no combination ensues. When the mineral or the soda contains sulphur or sulphuric acid, the glass ac- quires a deep yellow colour, which by the light of a lamp appears red, and as if pro- duced by copper. If the glass bead becomes opaque as it cools, so as to render the colour indistinct it should be broken, and a part of it mixed with more of the flux, until the colour be- comes more pure and distinct. To render the colour more perceptible, the bead may be either compressed before it cools, or drawn out to a thread. When it is intended to oxidate more highly a metallic oxide contained in a vi- trified compound with any of the fluxes, the glass is first heated by a strong flame, and when melted is to be gradually with- drawn from the point of the blue flame. This operation may be repeated several times, permitting the glass sometimes to cool, and using a jet of large aperture with the blow-pipe. The reduction of metals is effected in the following manner: The glass bead, formed after the manner already pointed out, is to be kept in a state of fusion on the charcoal as long as it remains on the surface, and is not absorbed, that the metallic particles may collect themselves into a globule. It is then to be fused with an additional quantity of soda, which will be absorbed by the char- coal, and the spot where the absorption has taken place is to be strongly ignited by a tube with a small aperture. By continuing this ignition, the portion of metal which was not previously reduced will now be brought to a metallic state; and the process may be assisted by placing the bead in a smoky flame, so as to cover it with soot that is not easily blown off. The greatest part of the beads which contain metals are frequently covered with a metallic splendour, which is most easily produced by a gentle, fluttering, smoky flame, when the more intense heat has ceased. With a moderate heat the metallic surface remains; and by a little practice it may generally be known whether the sub- stance under examination contains a metal or not. But it must be observed, that the glass of borax sometimes assumes exter- nally a metallic splendour. When the charcoal is cold, that part im- pregnated with the fused mass should be taken out with a knife, and ground with distilled water in a crystal, or what is much better, an agate mortar. The soda will be dissolved; the charcoal will float, arid may be poured off; and the metallic particles will remain in the water, and may be exa- mined. In this manner most of the metals may be reduced. BLO BLO Helations of the Earths and Metallic Oxides before the Blo-w-pipe. I. THE EARTHS. JBarytes, when containing water, melts and spreads on the charcoal. Combined with sulphuric acid, it is converted, in the interior flame, into a sulphuret, and is ab- sorbed by the charcoal, with effervescence, which continues as long as it is exposed to the action of the instrument. Strontites. Tf combined with carbonic acid, and held in small thin plates with platina forceps in the interior flame, the carbonic acid is driven off; and on the side of the plate farthest from the lamp, a red flame is seen sometimes edged with green, and scarcely perceptible but by the flame of a lamp. Sulphate of strontites is reduced in the interior flame to a sulphuret. Dissolve this in a drop of muriatic acid, add a drop .of alcohol, and dip a small bit of stick in the solution; it will burn with a fine red flame. Lime. The carbonate is easily rendered caustic by heat; it evolves heat on being moistened, and is afterwards infusible be- fore the blow-pipe. The sulphate is easily reduced to sulphuret, and possesses, be- sides, the property of combining with fluor at a moderate heat, forming a clear glass, The fluor should be rather in excess. Magnesia produces, like tbe strontites, an intense brightness in the flame of the blow-pipe. A drop of solution of cobalt be- ing added to it, and it being then dried and strongly ignited, a faint reddish colour like flesh is produced, which, however, is scarcely visible by the light of a lamp. And magnesia may by this process be detected in compound bodies, if they do not contain much metallic matter, or a proportion of alumina exceeding the magnesia. Some in- ference as to the quantity of the magnesia may be drawn from the intensity of the co- lour produced. All these alkaline earths, when pure, are readily fusible in combination with the fluxes into a clear, colourless glass, with- out effervescence; but on adding a further quantity of the earth, the glass becomes opaque. Alumina combines more slowly with the fluxes than the preceding earths do, and forms a clear glass, which does not become opaque. But the most striking character of alumina is the bright blue colour it ac- quires from the addition of a drop of ni- trate of cobalt, after having been dried and ignited for some time. And its presence may be detected in this manner in com- pound minerals, where the metallic sub- stances are not in great proportion, or the quantity of magnesia large. Alumina may be thus detected in the agalmatoUtc. II. THE METALLIC OXIDES. Arsenic flies off accompanied by its cha- racteristic smell, resembling garlic. When larger pieces of white arsenic are heated on a piece of ignited charcoal, no smell is perceived. To produce this effect the white oxide must be reduced, by being mixed with powdered charcoal. If arsenic is held in solution; it may be discovered by dip- ping into the solution a piece of pure and well-burned charcoal, which is afterwards to be dried and ignited. Chrome. Its green oxide, the form in which it most commonly occurs, and to which it is reduced by heating in the com- mon air, exhibits the following properties: it is fusible with microcosmic salt t in the in- terior flame, into a glass which at the in- stant of its removal from the flame, is of a violent hue, approaching more to the dark blue or red, according to the proportion of chrome. After cooling, the glass is bluish- green, but less blue than the copper glass. In the exterior flame the colour becomes brighter, and less blue, than the former. With borax it forms a bright yellowish, or yellow-red glass, in the exterior flame; and in the interior flame, this becomes darker and greener, or bluish-green. The reduc- tion with soda has not been examined. Molybdic acid melts by itself upon the charcoal with ebullition, and is absorbed. In a platina spoon it emits white fumes, and is reduced in the interior flame to mo- lybdous acid, which is blue; but in the ex- terior flame it is again oxidated, and be- comes white. With microcosmic salt, in the exterior flame, a small proportion of the acid gives a green glass, which by gradual additions of the acid passes through yel- low-green to reddish, brownish, and hya- cinth-brown, with a slight tinge of green. In the interior flame the colour passes from yellow-green, through yellow-brown and brown-red, to black; and if the proportion of acid be large, it acquires a metallic lus- tre, like the sulphuret, which sometimes remains after the glass has cooled. Molyb- dic acid is but little dissolved by borax. In the exterior flame the glass acquires a gray- yellow colour. In the interior flame, a quan- tity of black particles is precipitated from the clear glass, and leaves it almost colour- less when the quantity of molybdenum is small, and blackish when the proportion is larger. If to a glass formed of this acid and microcosmic salt a little borax be added, and the mixture fused in the exterior flame, the colour becomes instantly reddish- brown; in the interior flame the black par- ticles are also separated, but in smaller quantity. By long continued heat the co- lour of the glass is diminished, and it ap- pears yellower by the light of a lair.n than BLO BLO by day -light. This acid is not reduced by soda in the interior flame. Tungstic acid becomes upon the char- coal at first brownish-yellow, is then re- duced to a brown oxide, and lastly becomes black without melting- or smoking-. With microcosmic salt it forms in the interior flame a pure blue glass, without any violet ting-e; in the exterior flame this colour disappears, and re-appears again in the interior. With borax, in the internal flame, and in small proportions it forms a colourless gl-.ss, which, by increasing the proportion of the acid, becomes dirty gray, and then red- dish By long exposure to the external flame it becomes transparent, but as it cools it becomes muddy, whitish, and changea- ble into red when seen by day-light. It is not reduced. Oxide of Tantalum undergoes no change by itself, but is readily fused with micro- cosmic salt and with borax, into a clear co- lourless glass, from which the oxide may be precipitated by heating and cooling it alternately. The glass then becomes opaque, and the oxide is not reduced. Oxide of Titanium becomes yellowish when ignited in a spoon, and upon charcoal dark brown. With microcosmic salt it gives in the interior flame a fine violet-coloured glass, with more of blue than that from manganese. In the exterior flame this co- lour disappears. With borax it g-ives a dirty hyacinth colour. Its combinations with so- da have not been examined. Oxide of Cerium becomes red-brown when ignited. When the proportion is small it forms with the fluxes a clear colourless glass, which by increasing the proportion of oxide becomes yellowish -green while hot. With microcosmic salt, if heated a long time in the internal flame, it gives a clear co- lourless glass. With borax, under similar circumstances, it gives a faint yellow-green glass while warm, but colourless when cold. Exposed again for some time to the exter. nal flame, it becomes reddish-yellow, which colour it partly retains when cold. If two transparent beads of the compound with mici'ocosmic salt and with borax be fused together, the triple compound becomes opaque and white. Flies off by reduction. Oxide of Uranium. The yellow oxide by ignition becomes green or greenish brown. With microcosmic salt in the interior flame it forms a clear yellow glass, the colour of which becomes more intense when cold. If long exposed to the exterior flame, and fre- quently cooled, it gives a pale yellowish red-brown glass, which becomes greenish as it cools. With borax in the interior flame a clear, colourless, or faintly green glass, is formed, containing black particles, which appear to be the metal in its lowest state of oxidation. In the exterior flame this black VOL. I, matter is dissolved if the quantity be not too great, and the glass becomes bright yellowish -green, and after further oxida- tion yellowish-brown. If brought again into the interior flame, the colour gradually changes to green, and the black matter is again precipitated, but no farther reduc- tion takes place. Oxide of Manganese gives with microcos- mic salt in the exterior flame a fine amethyst colour, which disappears in the interior flame. With borax it gives a yellowish hya- cinth red glass. When the manganese, from its combina- tion with iron, or any other cause, does not produce a sufficiently intense colour in the glass, a little nitre may be added to it while in a state of fusion, and the glass then be- comes dark violet while hot, and reddish violet when cool: is not reduced. Oxide of Tellurium, when gently heated, becomes first yellow, then light red, and af- terwards black. It melts and is absorbed by the charcoal, and is reduced with a slight detonation, a greenish flame, and a smell of horse-raddish. JWicrocosmic salt dissolves it without being coloured. Oxide of Antimony is partly reduced in the exterior flame, and spreads a white smoke on the charcoal. In the interior flame it is readily reduced by itself, and with so- da. With microcosmic salt and with borax it forms a hyacinth-coloured glass. Metal- lic antimony, when ignited on charcoal, and remaining untouched, becomes covered with radiating acicular crystals of white oxide. Sulphuret of antimony melts on charcoal, and is absorbed. Oxide of Bismuth melts readily in a spoon to a brown glass, which becomes brighter as it cools. With microcosmic salt it forms a gray-yellow glass, which loses its trans- parency, and becomes pale, when cool. Add a further proportion of oxide, and it becomes opaque. With borax it forms a gray glass, which decrepitates in the inte- rior flame, and the metal is reduced and volatilized. It is most readily reduced by itself on charcoal. Oxide of Zinc becomes yellow when heated, but whitens as it cools. A small proportion forms with microcosmic salt and with borax a clear glass, which becomes opaque on increasing the quantity of oxide. A drop of nitrate of cobalt being added to the oxide, and dried and ignited, it be- comes green. With soda in the interior flame it is reduced, and burns with its cha- racteristic flame, depositing its oxide upon the charcoal. By tins process zinc may be easily detected even in the automolite. Mixed with oxide of copper, and reduced, the zinc will be fixed, and brass be obtain- ed. But one of the most unequivocal cha. racters of the oxide of zinc is to dissolve it 25 BLO BLO in vinegar, evaporate the solution to dry- ness, and expose it to the flame of a lamp, when it will burn with its peculiar flame. Oxide of Iron produces with microcosmic salt or borax in the exterior flame, when cold, a yellowish glass, which is blood-red while hot. The protoxide forms with these fluxes a green glass, which, by increasing the proportion of the metal, passes through bottle-green to black and opaque. The glass from the oxide becomes green in tb* inte- rior flame, and is reduced to protoxide, and becomes attractible by the magnet. When placed on the wick of a candle, it burns with the crackling noise peculiar to iron. Oxide of Cobalt becomes black in the exterior, and gray in the interior flame. A small proportion forms with microcosmic salt and with borax a blue glass, that with borax being the deepest. By transmitted light the glass is reddish. By farther addi- tions of the oxide it passes through dark blue to black. The metal may be precipita- ted from the dark blue glass by inserting a steel wire into the mass while in fusion. It is malleable if the oxide has been free from arsenic, and may be collected by the mag- net; and is distinguished from iron by the absence of any crackling sound when placed on the wick of a candle. Oxide of Nickel becomes black at the extremity of the exterior flame, and in the interior greenish-gray. It is dissolved rea- dily, and in large quantity, by microcosmic salt. The glass, while hot, is a dirty dark red, which becomes paler and yellowish as it cools. After the glass has cooled, it re- quires a large addition of the oxide to pro- duce a-distinct change of colour. It is near- ly the same in the exterior and interior flame, being slightly reddish in the latter. Nitre added to the bead makes it froth, and it becomes red-brown at first, and af- terwards paler. It is easily fusible with bo- rax, and the colour resembles the preced- ing. When this glass is long exposed to a high degree of heat in the interior flame, it passes from reddish to blackish and opaque; then blackish -gray, and translu- cent; then paler reddish-gray, and clearer; and, lastly, transparent; and the metal is precipitated in small white metallic glo- bules. The red colour seems here to be pro- duced by the entire fusion or solution of the oxide, the black by incipient reduction, and the gray by the minute metallic parti- cles before they combine and form small globules. When a little soda is added to the glass formed with borax, the reduction is more easily effected, and the metal collects itself into one single globule. When this oxide contains iron, the glass retains its own colour while hot, but assumes that of the iron as it cools. Oxide of Tin, in form of hydrate, and in its highest degree of purity, becomes yel- low when heated, then red, and when ap- proaching to ignition, black. If iron or lead be mixed with it, the colour is dark brown when heated. These colours become yel- lowish as the substance cools. Upon char- coal in the interior flame it becomes and continues white; and, if originally white and free from water, it undergoes no change of colour by heating. It is very easily reduced without addition, but the reduction is pro- moted by adding a drop of solution of soda or potash. Oxide of Lead melts, and is very quickly reduced, either without any addition, or when fused with microcosmic salt or bo- rax. The glass not reduced is black. Oxide of Copper is not altered by the ex- terior flame, but becomes protoxide in the interior. With both microcosmic salt and bo- rax it forms a yellow-green glass while hot, but which becomes blue-green as it cools. When strongly heated in the interior flame, it loses its colour, and the metal is reduced. If the quantity of oxide is so small that the green colour is not perceptible, its pre- sence may be detected by the addition of a little tin, which occasions a reduction of the oxide to protoxide, and produces an opaque, red glass. If the oxide has been fused with borax, this colour is longer pre- served; but if with microcosmic salt, it soon disappears by a continuance of heat. The copper may also be precipitated upon iron, but the glass must be first satu- rated with iron. Alkalis or lime promote this precipitation. If the glass containing copper be exposed to a smoky flame, the copper is superficially reduced, and the glass covered while hot with an iridescent pellicle, which is not always permanent af- ter cooling. It is very easily reduced by soda. Salts of copper, when heated before the blow-pipe, give a fine green flame. Oxide of Mercury before the blow-pipe becomes black, and is entirely volatilized. In this manner its adulteration may be dis- covered. The other metals may be reduced by themselves, and may be known by their own peculiar characters. * Under the particular mineral species their habitudes with the blow-pipe are given. Dr. Robert Hare, Professor of Natural Philosophy in the University of Philadel- phia, published, in the first volume of Bruce's Mineralogical Journal, an account of very intense degrees of heat, which he had produced and directed on different bo- dies, by a jet of flame, consisting of hydro- gen and oxygen gases, in the proportion requisite for forming water. The gases were discharged from separate gasometers, and were brought in contact only at a com- ELO BLO morv orifice or nozzle of small diameter, in which their two tubes terminated.f In the first number of the Journal of Sci- ence and Arts, is a description of a blow- pipe contrived by Mr. Brooke, and exe- cuted by Mr. Newman, consisting of a strong- iron box, with a blow-pipe nozzle and stop-cock, for regulating the emission of air, which had been previously condensed into the box, by means of a syringe screwed into its top. For this fine invention we are ultimately indebted to Sir H. Davy. John George Children, Esq. first proposed to him this application of Newman's apparatus for condensed air or oxygen, immediately after Sir H. had discovered that the explosion from oxygen and hydrogen would not com- municate through very small apertures; and lie first tried the experiment 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 explosion in burning the compressed gases, by suffering them to pass through a fine thermometer tube, $ of an inch diameter, and three inches in length; commenced a series of experiments, which were attended with most important and striking results. By the suggestion 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 blow-pipe nozzle. By this means, the dangerous explosions which had oc- curred so frequently, as would have deter- red a less intrepid experimenter than Dr. Clarke, are now obviated. It is still, howe- ver, a prudent precaution, to place a wood- en screen between the box and the opera- tor. The box is about five inches long, four broad, and three deep. The syringe is join- ed to the top of the box by a stop-cock. Near the upper end of the syringe, a screw nozzle is fixed in it at right angles, to which the stop-cock of a bladder contain- ing the mixed gases may be attached. When we wish to inject the gases, it is f My memoir on the supply and applica- tion of the blow-pipe, in which the fusion of the pure earths, and volatilization of pla- tinum, were first mentioned as practicable, was published in a separate pamphlet twelve years before the article on the com- pound blow-pipe appeared in Bruce's Jour- nal. This was a republication of a paper previously presented by Professor SiUiman to the Connecticut Academy of Sciences, proper to draw the piston to the top, be- fore opening the lower stop-cock, lest the flame of the jet should be sucked back- ward, and cause explosion. It is likewise necessary to see that no little explosion, has dislodged the oil from the safety cy- linder. 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 finely fused the astonishing quantity of half an ounce at once, by this jet of flame. In small quan- tities, it burns like iron wire. Palladium melted like lead. Pure lime becomes a wax- yellow vitrification. A lambent purple flame always accompanies its fusion. The fusion of magnesia is also attended with combus- tion. Strontites fused with a flame, of an intense amethystine colour, and after some minutes there appeared a small oblong mass of shining matter in its centre. Silex instant- ly melted into a deep orange -coloured glass, which was partly volatilized. Alumina melt- ed with great rapidity into globules of a yellowish transparent glass. In these expe- riments, supports of charcoal, platinum or plumbago, were used with the same effect. The alkalis were fused and volatilized the instant they came in contact with the flame, with an evident appearance of combustion. The following refractory native com- pounds were fused. Rock crystal, white quartz, noble opal, flint, calcedony, Egyp- tian jasper, zircon, spinelle, sapphire, to- paz, cymophane, pycnite, andalusite, wa- velite, rubellite, hyperstene, cyanite, talc, serpentine, hyalite, lazulite, gadolinite, leu- cite, apatite, Peruvian emerald, Siberian be- ryl, potstone, hydrate of magnesia, subsul- phate of alumina, pagodite of China, Iceland spar, common chalk, Arragonite, diamond. Gold exposed on pipe-clay to a flame, was surrounded with a halo of a lively rose co- lour, and soon volatilized. Stout iron wire was rapidly burned. Plumbago was fused into a magnetic bead. Red oxide of titani- um fused, with partial combustion. Red ferriferous copper, blende, oxides of plati- num, gray oxide of manganese, crystalliz- ed oxide of manganese, wolfram, sulphuret of molybdenum, siliceo-calcareous titani- um, black oxide of cobalt, pechblende, si- liciferous oxide of cerium, chromate of iron, and ore of iridium, were all, except the second and last, reduced to the metal- lic state, with peculiar, and for the most part, splendid phenomena. Jade, mica, ami- anthus, 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 1'Aigle, and its BLO BLO 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 ex- posed to the ignited gas. It fused with ve- hement ebullition, and metallic globules were clearly discernible in the midst of the boiling fluid, suddenly forming, and as sud- denly disappearing. On checking the flame, the cavity of the charcoal was studded over with innumerable globules of a metafc of the most brilliant lustre and whiteness, re- sembling 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 ba- rium and one of platinum, each weighing one grain. The bronze coloured alloy weigh- ed two grains, proving a real combination. The alloy of barium and iron is black and brittle. Barium is infusible before the blow- pipe, Per se,- but with borax it dissolves like barytes, with a chrysolite green co- lour, and disclosing metallic lustre to the file. The alloy of barium and copper is of a vermilion colour. When si lex is mixed into a paste with lamp-oil, and exposed 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 al- loy of silicium and iron is obtained, which discloses a metallic surface to the file. Mag- nesium 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 has more lately revived barium in larger quantities, so as to exhibit its qualities for some time. It gradually, however, passes again into pure barytes Muriate of rhodium, placed in a charcoal crucible, yielded the metal rho- dium, brilliant like platinum. It is mallea- ble on the anvil. Oxide of uranium, from Cornwall, was also reduced to the metallic state.f | How far Dr. Ure has done me justice in this article, will be seen more fully in the strictures which I have lately publish- ed on " Clarke's gas blow-pipe," in Silli- roan's Journal, No. 2, vol. 2. fiut it may be sufficient to subjoin the following article translated into No. 1, vol. 3d. of the same journal, from the Annalesde Chirnie From this it appears, that Dr. Clarke's plagia- risms are not likely to receive the counte- nance in France, which he has managed to prof ure for them in his own country. " The blow-pipe of Hare was described in the Annals of Chemistry, (Vol. 45, p. 113.) It is supplied by two streams, one of tVe shall conclude this ai'ticle by the fol- lowing experiment of Dr. Clarke's: If you take up two pieces of lead foil and plati- hydrogen and the other of oxygen, which do not mix till the moment of their com- bustion; and consequently are attended by no kind of danger. This blow-pipe is in this respect far preferable to that of Ne - vman, or rather of Brooke, who appears to have been the first inventor, and it is not inferior to it, or only in a very slight degree, in in- tensity of heat. We can besides supply it with hydrogen gas and oxygen gas, com- pressed each in its own reservoir; but, if we were to judge of it by the effects pro- duced by this instrument, and by that of Brooke, there is but little advantage in having recourse to this means. " Lavoisier, as is well known, by direct- ing oxygen gas upon burning charcoal, suc- ceeded in melting and volatilizing some substances, which, till that time, had been considered as infusible and fixed. (Me"m. de 1'Acad. 1782 et 1783). He melted alu- mine, and many of its mixtures; but he did not succeed in melting silex, barytes, lime and magnesia. " Mr. Hare, by means of his blow-pipe, perfectly melted alumine, silex and barytes, but with great difficulty, lime and magne- sia. He brought silver and gold to a state of ebullition, and succeeded, almost in- stantly, in volatilizing completely, globules of platina of more than a line in diameter. (Ann. de Chim. XLV. 134. et LX. 82.) "Some years Afterwards, Mr. Silliman, Professor of Chemistry and Mineralogy, who had co-operated in the early experi- ments of Mr. Hare, performed new ones, which were published in 1813, in the first volume of the Memoirs of the Connecticut Academy of Arts and Sciences; we proceed to give the principal results. " Alumine was perfectly melted into a milk white enamel. " Silex, into a colourless glass. " Barytes and strontian into a grayish white enamel. " Glucine and Zircon were perfectly melt- ed into a white enamel. " Lime, prepared by the calcination of Carrara marble, was melted into a per- fectly white and brilliant enamel " The splendor of the light was such that the eye, when naked, and even when pro- tected by deeply coloured glasses, could not sustain it. The lime was seen to become rounded at the angles, and gradually to sink down; and in a few seconds, there re- mained only a small globular mass. " Magnesia was affected almost exactly as lime; the light reflected was equally vi- vid; ihe surface was melted into small vi- treous globules. BOL num 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 1 their melted particles off the charcoal, 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 glo- bule of^ sapphire blue colour. Also, if the platinum and lead be placed beside each other, as soon as the platinum becomes heated, you will observe a beautiful play of blue light upon the surface of the lead, be- coming highly iridescent before it melts.* * BLUE (PRUSSIAN). A combination of oxide of iron with an acid distinguished by the name of \\\efcrro-prussic. See ACID (PRUSSIC), and IRON.* BLUE (SAXON). The best Saxon blue co- lour may be given by the following compo- sition: Mix one ounce of the best powdered in- digo 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 whole 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. See ORES OF IRON. * BOLE. A massive mineral, having a per- " Platina was not only melted, but vola- tilized with strong ebullition. " A great number of minerals, such as rock crystal, chalcedony, beryl, Peruvian emerald, peridot (chrysolite), amphigene (leucite), disthene (sappare), corundum, zircon, spinel-ruby, &c. melted with the greatest facility. " In subsequent experiments, which Mr. Silliman has communicated to us, platina, gold, silver, and manv other metals were not only rapidly vaporized, but entered, at the same time, into beautiful and vivid combustion. " Although the experiments of Mr. Sil- liman date in 1812, we have thought that they ought to be known upon our conti- nent. They demonstrate, on the one hand, that Mr. Clarke has been anticipated in America, with respect to the fusion of bo- dies in the flame of hydrogen and oxygen; and on the other, that the blow-pipe of Hare gives results almost perfectly identi- cal with those of Brooke.'* BOL fectly conchoidal fracture, a glimmering- internal lustre, and a shining streak. Its colours are yellow-red, and brownish-black, when it is called mountain soap. It is trans- lucent, 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. gr. 1.4 to 2. It may be polished. If it be immersed in water after it is dried, it falls asunder with a crackling 1 noise. It occurs in wacke and basalt, in Si* lesia, Hessia, and Sienna in Italy, and also in the clifts of the Giant's ( lauseway, Ire- land. The black variety is found in the trap rocks of the Isle of Sky.* BOLOGNIAN STONE. Lemery reports, that an Italian shoemaker, named Vincen- zo Casciarolo, first discovered the phos- phoric 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 mu- cilage; and this paste, divided into pieces a quarter of an inch thick, and dried in a moderate 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' ex- posure to the sun's rays, will give light enough in the dark to render the figures on the dial-plate of a watch visible. * BOLETIC ACID. See ACID (BOLE- TIC)* * BOLETUS. A genus of mushroom, of which several species have been subjected to chemical examination by M. M. Bracon- not and Bouillon La Grange. 1. Boletus juglandis, in 1260 parts, yield- ed, 1118.3 water, 95.68 fungin, 18 animal matter insoluble in alcohol, 12 osmazome, 7.2 vegetable albumen, 6 fungate of potash, 1.2 adipocere, 1.12 oily matter, 0.5 sugar of mushrooms, and a trace of phosphate of potash. 2. Boletus lands , used on the continent in medicine, under the name of agaric. 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 wa- ter is yellowish, sweet-tasted, and reddens vegetable blues. It contains muriate of pot- ash, sulphate of lime, and sulphate of pot- ash. Water boiled on agaric, becomes ge- latinous on cooling; and if the water be dis- sipated by evaporation, ammonia is exhaled by the addition of lime. Resin of a yellow colour, with a bitter sour taste, may be ex- tracted from it by alcohol. It yields ben- zoic acid, by Sheele'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. BON EON 3. JBoletus igniarius is found in most countries, and particularly in the Highlands of Scotland, on the trunks of old ash and other trees. The French and Germans pre- pare 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 re- commended in surgery, for stopping hae- morrhage from wounds. It imparts to^wa- ter a deep brown colour, and an astringent taste. The liquid consists of sulphate of lime, muriate of potash, and a brown extractive matter. When the latter is evaporated to dryness, and burned, it leaves a good deal of potash. Phosphates of lime and magne- sia, 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 Bra- connot, water, fungin, a sweetish mucilage, boletate of potash, a yellow fatty matter, vegetable albumen, a little phosphate of potash, acetate of potash, and fungic acid combined with a base. 5. Boletus viscidus was found by Bracon- not to be composed, in a great measure, of an animal mucus, which becomes cohesive by heat.* BONE. The bones of men and quadrupeds 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 af- ford gelatinous matter, and a portion of fat or oil, which occupied their interstices. * Calcined human bones, according to Berzelius, are composed, in 100 parts, of 81.9 phosphate of lime, 3 fiuate of lime, 10 lime, 1.1 phosphate of magnesia, 2 soda, and 2 carbonic acid. 100 parts of bones by cal- cination 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 car- bonate of lime, and 1.3 phosphate of magne- sia; but Berzelius 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 phosphate of mag- nesia, 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 dis- solved in muriatic acid, it leaves no albu- men, 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 compo- sition at 78 phosphate 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 phos- phate of lime, 6 carbonate of lime, 20 car- tilage, and 10 water or loss. The fossil bones from Gibraltar, are composed of phos- phate 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 centuries, still retain thefr albu- men, with very little diminution of its quan- tity.* 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 phos- phate 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 Hat- chett observes, that the enamel of tooth 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 ani- mals 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 ani- mals will be a fortnight 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 log- wood too, in considerable quantity, will tinge the bones of young pigeons purple. On desisting from the use of this food, how- ever, 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- 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 woodv parts of trees. But he was mistaken 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. BOR BOR ( Bones are of extensive use in the arts. In their natural state, or dyed of various co- lours, 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 1 articles of paste, and some other trinkets, by the name of burnt harts- horn. 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 em- ployed in their stead. On this principle, Mr. Proust has recom- mended an economical use of bones, parti- cularly with a view to improve the subsis- tence 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 purposes 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, till 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 productive 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 (BORACIC). This acid has been found native on the edges of hot springs, near Sapo in the terri- tory of Florence; also attached to specimens from the Lipari Islands, and from Monte Kotondo, to the west of Sienna. It is in small pearly scales, and also massive; fusing at the flame of a candle into a glassy glo- bule. 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 uneven, or imperfectly conchoidal Shining greasy lustre; translucent; so hard as to strike fire with steel; of a yellowish, gray- ish, or greenish-white. Sp. grav. 2.56. It becomes electric by heat; and the diagon- ally-opposite solid angles, are in opposite electrical states. It fuses into a yellow en- amel, 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 Brunswick, and at Segeberg, near Kiel in Holstein.* BORAX. The origin of Borax was for a long time unknown in Europe. Mr. Grill Abrahamson, however, sent some to Swe- den 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, informs us, that this salt is abundantly ob- tained at the mines of Riquintipa, and those in the neighbourhood of Escapa, where it is used by the natives in the fusion of cop- per ores. The purification of borax by the Vene- tians and the Hollanders, was for a long time kept secret. Chaptal finds, after try- ing 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 solution being filtered, affords by evaporation crystals, which are some- what foul, but may be purified by repeat- ing the operation. Purified borax is white, transparent, ra- ther 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 sirup of violets to a green: and when exposed to heat, it swells up, boils, loses its water of crvstalliza- tion, and becomes converted into a porous, white, opaque mass, commonly called Cal- cined Borax. A stronger heat brings it into a state of quiet fusion; but the glassy sub- stance thus afforded, which is transparent, and of a greenish-yellow colour, is solu- ble 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 boiling heat dissolves three times this quantity. Its component parts, accord- ing to Kirwan, are, boracic acid 34, soda 17, water 47- For an account of the neu- tral borate of soda, and other compounds of this acid, see ACID (BORACIC). Borax is used as an excellent flux in clo- cimastic operations. It enters into the com- position of reducing fluxes, and is of the BOV BRA greatest use in analysis by the blow-pipe. It may be applied with advantage in glass manufactories; for when the fusion turns out bad, a small quantity of borax re-es- tablishes it. It is more especially used in soldering; it assists the fusion of the sol- der, causes it to flow, and keeps the sur- face of the metals in a soft or clean state, which facilitates the operation. It is scarce- ly of any use in medicine. Its acid, called Sedative Salt, is used by some physicians; and its name sufficiently indicates its sup- posed effects. Mixed with shell lac, in the proportion of one part to five, it renders the lac soluble by digestion in water heat- ed near boiling. * BORON. The combustible basis of bo- racic acid, which see.* * BOTANY BAY RESIN exudes spon- taneously from the trunk of the acarois re- sinifera of New Holland, and also from the wounded bark. It soon solidifies by the sun, into pieces of a 3 r ellow colour of various sizes. It pulverizes easily without caking; nor does it adhere to the teeth when chew- ed. It has a slightly sweet astringent taste. It melts at a moderate heat. When kindled, it emits a white fragrant smoke. It is in- soluble in water, but imparts to it the fla- vour of storax. Out of nine parts, six are soluble in water, and astringent to the taste; and two parts are woody fibre.* * BOTRYOLITE is a mineral which oc- curs in mamillary concretions, formed of concentric layers; and also in botryoidal masses, white and earthy. Its colour is pearl and yellowish -gray, with sometimes reddish-white concentric stripes. It has a rough and dull surface, and a pearly lus- tre internally. Fracture delicate stellular fibrous. Translucent on the edges. Brittle, but moderately hard. Sp. grav. 2.85. It is composed of 36 silica, 39.5 boracic acid, 13 5 lime, 1 oxide of iron, 6.5 water. It froths and fuses before the blow-pipe 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.* *BOURNONITE. Anantimonial sulphuret of lead.* BOVEY COAL. This is of a brown or brownish-black colour; and lamellar tex- ture; the laminze are frequently flexible when first dug, though generally they harden when exposed to the air. It con- sists of wood penetrated with petroleum or bitumen, and frequently contains py- rites, alum, and vitriol; its ashes afford a small quantity of fixed alkali, according to the German chemists; but according to Mr. Mills, they contain none. By distillation it yields an ill-smelling liquor, mixed with volatile alkali and oil, part of which is so- luble in alcohol, and part insoluble, being of a mineral nature. It is found in England, France, Italy, Switzerland, 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 at- tention. 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 becomes solid, and fri- able like old cheese. Exposed 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 pun- gent 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 filtra- tion. 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 al- kaline phosphate in solution. Acids se- parate a white coagulum from it; and form salts with bases of lime, soda, and ammo- nia. Alcohol too coagulates it. Caustic fixed alkalis act very powerfully on brain even cold, evolving much ammo- nia and caloric. With heat they unite with it into a saponaceous substance. The action of alcohol on brain is most remarkable. 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 ma- trass with a grooved stopple, the three first portions of alcohol, decanted boiling depo- sited by cooling brilliant laminae of a yel- lowish-white colour, diminishing in quan- tity each time The fourth deposited very little. The cerebral matter had lost 5-8ths of its weight; and by the spontaneous de- position, and the subsequent evaporation of the alcohol, half of this was recovered in needly crystals, large scales, or granu- lated matter. The other half was lost by volatilization. This crystallized substance, of a fatty appearance, was agglutinated in- to a paste under the finger; but did not melt at the heat of boiling water, being merely softened. At a higher temperature it suddenly acquired a blackish-yellow co- lour, and exhaled during fusion an em- pyreumatic and ammoniacal smell. This shows that it is not analogous to sperma- ceti, or to adipocere; but it seems more to resemble the fat lamellated crystals con- tained in some biliary calculi, which, how- ever, do not soften at a heat of 234 F. or become ammoniacal and empyreumatic at BRA BRA this temperature, as the crystalline cere- bral oil does. 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 ap- pearance, reddened litmus paper, and did not become really oily, or fusible after the manner of an oil, till it had given out am- monia, and deposited carbon, by the action of fire or caustic alkalis. A similar action of alcohol on the brain, nerves, and spinal marrow, is observed af- ter long 1 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 osmuzome, 1.5 phosphorus, 5.15 acids, salts, and sul- phur. The medulla oblongata and nerves have the same chemical composition.* The spontaneous change that brain un- dergoes in certain situations, has already been noticed under the article AD IPO- CERE. BRANDY. This well known fluid is the spirit distilled from wine. The greatest quantities are made in Languedoc, where this manufacture, upon the whole so perni- cious to society, first commenced. It is ob- tained by distillation in the usual method, by a still, which contains five or six quin- tals of wine, and has a capital and worm tube applied. Its peculiar flavour depends, no doubt, on the nature of the volatile prin- ciples, or essential oil, which come over along with it, and likewise, in some mea- sure, 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 pro- portion of nitrous ether to the spirit of malt or molasses. See ALCOHOL. BRASS. An elegant yellow-coloured com- pound metal, consisting of copper com- bined with about one-third of its weight of zinc. The best brass is made by cementa- tion of calamine, or the ore of zinc, with granulated copper. See COPPER. BRASSTCA RUBRA. The red cabbage af- fords a very excellent test both for acids and alkalis; in which it is superior to lit- mus, 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 VOL. I. 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 caesalpina 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 becomes deeper by exposure to the air The various specimens diiier 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 san- dal, 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 mar- ble 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 precipi- tate, or lake, which is increased in quantity by the addition of alkali to the liquor. The crimsonrred colour is also precipitated by muriate of tin; but it is darkened by the salts of iron. Acids change it to yellow, from which, however, solution of tin re- stores it to its natural hue. The extract of brazil wood reddens litmus paper, by de- priving it of the alkali which darkens it.* BREAD. I am not acquainted with any set of experiments regularly instituted and carried into effect, for ascertaining what happens in the preparation of bread. Fari- naceous vegetables are converted into meal by trituration, or grinding in a mill, and when the husk or bran has been separated by sifting or bolting, the powder is called flour. This is composed of a small quantity of mucilaginous saccharine matter, solu- ble in cold water, much starch, which is scarcely soluble in cold water, but com- bines with that fluid by heat, and an adhe- sive gray substance insoluble in water, al- BRE BUE cohol, oil, or ether, and resembling an ani- mal substance in many of its properties. See WHEAT, STARCH, GLUTEN (VEGE- TABLE), MUCILAGE. When flour is kneaded tog-ether \vith 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, ren- dering the compound more easy to Aasti- cate, as well as to digest. Hence the first approaches towards the making of bread consisted in parching 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 consistent; of all which we have sufficient indications in the histories of the earlier nations, as well as in the various practices of the moderns. It ap- pears likewise from the Scriptures, that the practice of making leavened bread is of very considerable antiquity; but the addi- tion 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 shipping in large quantities; but most of the bread used on shore is made to under- go, previous to baking, a kind of ferment- ation, which appears to be of the same na- ture as the fermentation of saccharine sub- stances; but is checked and modified by so many circumstances, as to render it not a little difficult to speak with certainty and precision respecting it. See FERMENTA- TION. 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 hu- midity, the thickness or thinness of the part, the vicinity or remoteness of fire, and other circumstances less easily investigated. The saccharine partis disposed to become converted into alcohol, the mucilage has a tendency to become sour and mouldy, \vlule the gluten in all probability verges toward the putrid state. An entire change in the chemical attractions of the several compo- nent parts must then take place in a pro- gressive manner, not altogether the same in the internal and more humid parts as in the external parts, which not only become 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 altera- tion, 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 digestible 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 pro- cess, by evaporating great part of the mois- ture which is requisite to favour the che- mical attraction, and probably also by still farther changing the nature of the compo- nent parts. It is then bread. Bread made according to the preceding method will not possess the uniformity which is requisite, because some parts may be mouldy, while others are not yet suffi- ciently changed from the state of dough. The same means are used in this case as have been found effectual 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 fermentation with greater speed, but causes it to take place in the whole of the mass at the same time; and as soon as the dough has by this means acquired a due increase of bulk from the carbonic acid, which en- deavours to escape, it is judged to be suffi- ciently 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 from true vinegar. Bread raised by leaven is usually made of a mix- ture 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 the king- dom, where it is raised on one and the same piece of ground, and passes through all the processes of reaping, threshing-, grinding, &c. in this mixed state. Yeast or barm is used as the ferment for the finer kinds of bread. This is the muci- laginous 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 ferment- ation than that obtained by leaven, and the bread is accordingly much lighter, and 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. BRE BRE 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 of brittle- ness is given by the addition of butter or fat. White of egg-, gum-water, isinglass, and other adhesive substances, are used, when it is intended that the effect of fer- mentation shall expand the dough into an exceedingly porous mass. Dr. Percival has recommended the addition of salep, or the nuti'itious 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 remark- ably 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 quan- tity, however, its peculiar taste will be dis- tinguishable in the bread. The farina of potatoes likewise, mixed with wheaten flour, makes very good bread. The reflect- ing chemist will receive considerable in- formation on this subject from an attentive inspection of the receipts to be met with in treatises of cooking and confectionary. * Mr. Accum, in his late Treatise on Cu- linary Poisons, states, that the inferior kind'of flour which the London bakers ge- nerally use for making loaves, requires the addition of alum to give them the white appearance of bread made from fine flour. " The baker's 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, secondsj middlings, fine middlings, coarse middlings, and twen- ty-penny flour. Common garden beans and peas are also frequently ground up among the London 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, 1 have my own baker's au- thority to state, is from three to four ounces to a suck of flour weighing 240 pounds." " The following account of making a sack or five bushels of flour into bread, is taken from Dr. P. Markham's considerations on the ingredients used in the adulteration of flour and bread, p. 21. Fiv bushels of flour, Eight ounces of alum, Four Ibs. salt, Haifa 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 consideration of producing light and por- ous bread from spoiled, or what is techni- cally called sour four. This salt, which be- comes wholly converted into a g'aseous substance during the operation of baking, causes the dough to swell up into air bub- bles, which carry before them the stiff, dough, and thus it renders the dough por- ous; the salt itself is at the same time to- tally 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, showing that from twenty to forty grains of common carbonate of magnesia, well mixed with a pound of the worst neiv se- conds flour, materially improved the qua- lity of the bread baked with it. The habitual and daily introduction of a portion of alum into the human stomach, however 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 infei'ior and highly acescent food; which cannot fail to aggra- vate dyspepsia, and which may generate a calculous diathesis in the urinary organs. Every precaution of science and law ought therefore to be employed to detect and stop such deleterious adulterations. Bread may be analyzed for alum by crumbling it down when somewhat stale in distilled wa- ter, 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 pro- cure it clear if we use new bread or hot water. A dilute solution of muriate of ba- rytes 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 precipi- tate by this treatment. The earthy adulte- rations are easily discovered by incinerat- ing the bread at a red heat in a shallow earth vessel, and heating the residuary ashes with a little nitrate of ammonia. The eai-ths themselves will then remain, charac- terized by their whiteness and insolubility. The latest chemical treatise en the art of making bread, except the account given by Mr. Accum in his work on the adulterations of food, is the article Baking in the Supple- ment to the Encyclopaedia Britannicu, -a BRE BRE work adorned by the dissertations of Biot, within a few periods to reduce the adulte= Brande, Jeffrey, Lesley, Playfair, and Stew- ration to one ounce? That this voluntary abstraction of -||- 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 some of his friends had invent- ed a new yeast for fermenting dough by mixing- a quart of beer barm with a paste made often pounds of flour and two gal- lons of boiling water, and keeping this mixture warm for six or eight hours. " Yeast made in this way,' 1 says he, " an- swers the purposes of the baker much bet- ter than brewer's yeast, because it is clear- er, and free from the hop mixture, which sometimes injures the yeast of the brewer. Some years ago the bakers of London, sen- sible of the superiority of this artificial yeast, invited a company of manufacturers from Glasgow to establish a manufactory art Under Process of Baking 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, call- ed 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 passage. " In London, where the goodness of bread is estimated emirely 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 of it in London, and promised to use no A ~ ' other. About 5000/. accordingly were laid out on buildings and materials, and the manufactory was begun on a considerable 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 jour- neymen accordingly declared in a body, that they would work no more for their masters unless they gave up taking any more veast from the new manufactory. The masters were obliged to comply; the new manufactory was stopped; and the inhabi- tants of London -were obliged to continue to eat ivorse bread, because it -was the interest of the ale brewers to sell the yeast. Such is the influence of journeymen bakers in the metropolis of England!" This doleful diatribe seems rather ex- travagant; for surely beer-yeast can derive nothing noxious to a porter-drinking peo- ple, from a slight impregnation of hops] London joined in a conspiracy to supply the citizens with bad bread. We may hence infer, that the full allowance he assigns of 2i 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 quartern loaves, we have 2? pounds divided by 80, or = 197 grains, for the quantity 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 several 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 ad- ding it given by the London bakers is, that it renders 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 occasioning constipation. But if while it must form probably a more ener we consider the small quantity of this salt getic ferment than the fermented paste ol added by the baker, not quite j$ grains to the new company, which at any rate could a quartern loaf, we will not readily admit these allegations. Suppose an individual to cat the seventh part of a quartern loaf a- duy, 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 be prepared in six or eight hours by an\ baker who found it to answer his purpose of making a pleasant eating bread. But i1 is a very serious thing for a lady or gentle man of sedentary habits, or infirm consti tution, to have their digestive process dail] itiated by damaged flour, whitened wit! suppose that half a grain of alum* swal- 197 grains of alum per quartern loaf. Aci lowed at different times during the course dity of stomach, indigestion, flatulence of a day, should occasion constipation." headaches, palpitation, costiveness, am Is it not more absurd to state 2i pounds, urinary calculus, may be the probable con or 36 ounces, as the alum adulteration of sequences of the habitual introduction o a sack of flour by the London bakers, and so much acidulous and acescent matter. BUI BRO 1 have made many experiments on bread, and have found the "proportion of alum 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, spongi- ness, and agreeableness of taste, is un- doubted, since the bread baked at the esta- blishment of Mr. Harley of Willowbank, Glasgow, in which about 20 tons of flour are converted into loaves in the course of a week, unites every quality of appearance, with an absolute freedom from that acido- astringent drug. He uses six pounds of salt 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 flour, see WHEAT.* BRECCIA. An Italian term, frequently used by our mineralogical writers to de- note such compound stones as are com- posed of agglutinated fragments of consi- derable 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 breccia, or mar- bles, and siliceous breccias, which are still more minutely classed, according to their varieties. BREWING. See BEER, ALCOHOL, and FERMENTATION. BRICK. Among the. numerous branches of the general art of fashioning argillaceous earths into useful forms, and afterward har- dening 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 n 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 con- siderable time, andthen exposed them to the open air for three years. They were formed of clay 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 crum- bled down by the action of the air; such as had been more thoroughly burned suf- fered 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 pro- portion 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. Where a vitreous crust might be deemed necessary, he recom- mends the projection of a due quantity of salt into the furnace, which would produce the effect in the same manner as is seen in the fabrication of the English pottery call- ed stone-ware. A kind of bricks called fire-bricks are made from slate-clay, which are very hard, heavy, and contain a large proportion of sand. These are chiefly used in the con- struction of furnaces for steam-engines, or other large works, and in lining the ovens of glass-houses, as they will stand any de- gree 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 ancients; and Fabbroni discovered some years since a substance, at Castel del Pi- ano, near Santa Fiora, between Tuscany and the States of the Church, from which similar bricks might be made. It consti- tutes a brown earthy bed, mixed with the remains of plants. Haiiv calls it talc pulve- rulent silicifere, and Brochant considers it as a variety of meerschaum. The Germans name it bergmehl, (mountain meal), and the Italians latte di tuna, (moon milk). By Klap- roth's analysis, it consists of 79 silica, 5 alumina, 3 oxide of iron, 12 water, and 1 loss, in 100 parts. It agrees nearly in com- position with Kieselguhr* BRIMSTONE. See SULPHUR. * BRIONIA ABBA. A root used in medi- cine. By the analysis of Vauquelin, it is found to consist in a great measure of starch, with a bitter principle, soluble in water and alcohol, some gum, a vegeto- animal matter, precipitable by infusion of galls, some woody fibre, a little sugar, and supermalate and phosphate of lime. It has cathartic powers; but is now seldom pre- scribed by physicians.* BROCATELLO. A calcareous stone or marble, composed of fragments of four co lours, white, gray, yellow, and red. 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. * BRONZ.ITE. This massive mineral has a pseudo-metallic lustre, frequently resem- bling bronze. Its colour is intermediate between yellowish-brown and pinchbeck- brown. Lustre shining; structure lamellar BRU BUT with joints, parallel to the lateral planes of a rhomboidal prism; the fragments are streaked on the surface. It is opaque in mass, but transparent in thin plates. White streak; somewhat hard, but easily broken Sp. grav. 3.2 It is composed 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 Sti- ria; and in a syenitic rock in Glen T^lt, in Perthshire.* * BROWN SPAR. Pearl Spar, or Sidero- calcite. It occurs massive, and in obtuse rhomboids with curvilinear faces. Its co- lours are white, red, and brown, or even pearl-gray and black. It is found crystal- lized 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 semi-transparent; it is easily broken into rhomboidal fragments. It effervesces slow- ly with acids. It is composed of 49.19 car- bonate of lime, 44.39 carbonate of magne- sia, 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 co- lour, and massive.* * BRUCIA, or BRUCINE. A new vegeta- ble alkali, lately extracted from the bark of the false angustura, or Jirucea antidy- senterica, by M.M. Pelletier and Caventou. After being treated with sulphuric ether, to get rid of a fatty matter, it was subjec- ted to the action of alcohol. The dry resi- duum from the evaporated alcoholic solu- tion, was treated with Goulard's extract, or solution of sub-acetate of lead, to throw down the colouring matter, and the excess of lead was separated by a current of sul- phuretted hydrogen. The nearly colourless alkaline liquid was saturated witli oxalic acid, and evaporated to dryness. The sa- line mass being freed from its remaining colouring particles, by absolute alcohol, was then decomposed by lime or magne- sia, when the brucia was disengaged. It was dissolved in boiling alcohol, and ob- tained in crystals, by the slow evaporation of the liquid. These crystals, when ob- tained by very slow evaporation, are ob- lique prisms, the bases of which are par- allelograms. When deposited from a satu- rated solution in boiling watt- r, 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 colouring 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 as- sume the appearance of wax. At a strong- heat, it is resolved into carbon, hydrogen, and oxygen; without any trace of azote. It combines with the acids, and forms both neutral and super-salts. Sulphate of bru- cia crystallizes in long slender needles, which appear to be four-sided prisms, ter- minated by pyramids of extreme fineness. It is very soluble in water, and moderately in alcohol. Its taste is very bitter. It is de- composed by potash, soda, ammonia, ba- rytes, 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 ob- lique face. It is permanent in the air, and very soluble in water. It is decomposed by sulphuric acid. Concentrated nitric acid destroys the alkaline basis of both these salts. The muriate consists of Acid, 5.953 4.575 Brucia, 94.046 72.5 Phosphate of brucia, is a crystallizable, soluble, and slightly efflorescent salt. The nitrate forms a gummy-looking mass; the binitrate crystallizes in acicular four-sided prisms. An excess of nitric acid decom- poses the brucia. into a matter of a fine red colour Acetate and oxulate of brucia both crystallize. Brucia is insoluble in sul- phuric ether, the fixed oils, and very slightly in the volatile oils. When admin- istered" internally, it produces tetanus, and acts upon the nerves without affecting the brain, or the intellectual faculties. Its in- tensity is to that of strychnia, as 1 to 12. From the discrepancies in the prime num- ber for brucia, deduced from the above analyses, we see that its true equivalent re- mains to be determined. See Journal de Pharmacie, Dec. 1819.* BRUNSWICK GREEN. This is an ammo- niaco-muriate of copper, much used for paper-hangings, and on the continent in oil painting. See COPPER. * BUNTKUPFERZ. Purple copper ore.* BUTTER. The oily inflammable part of milk, which is prepared in many countries as an article of food. The common mode of preserving it is by the addition of salt, which will keep it good a considerable time, if iu sufficient quantity. Mr. Eaton CAC CAD 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 melting if carefully done, injures neither the taste nor colour. Thenard, too, recommends the Tartarian method. He di- rects the melting to be done on a water- bath, or at a heat not exceeding 180 F.; and to be continued till all the caseous matter has subsided to the bottom, and the butter is transparent. It is then to be de- canted, or strained through a cloth, and cooled in a mixture of pounded ice and salt, or at least in cold spring water, other- wise it will become lumpy by crystalliz- ing, 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 off. If beaten up with one-sixth of its weight of \ the cheesy matter when used, it will in some degree resemble fresh butter in ap- pearance. 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 composition 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 va- cuities. This butter does not taste well, till it has stood at least a fortnight; it then has a rich marrowy 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 informs us, there is a tree much resem- bling the American oak, producing a nut in appearance somewhat like an olive. The kernel of this nut, by boiling in water, af- fords 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 t or tree butter. Large quantities of it are made every sea- son. BUTTER OP ANTIMONY. See ANTI- MONY. BUTTER or CACAO. An oily concrete white matter, of a firmer consistence than suet, obtained from the cacao nut, of which chocolate is made. The method of separat- ing it consists in bruising the cacao and boiling it in water. The greater part of the superabundant and uncombined oil contain- ed 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 seve- ral matters have arranged themselves ac- cording 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 general properties and habitudes, it resem- bles fat oils; among which it must there- fore be classed. It is used as an ingredient in pomatums. BUTTER OF TIN. See TIN. * BYSSOLITE. A massive mineral, in short and somewhate stiff filaments, of an olive-green colour, implanted perpendi- cularly like moss, on the surface of cer- tain stones. It has been found at the foot of Mount Blanc, and also near Oisans-on- gneiss.* C CABBAGE (RED). See BRASSICA. Ru- BRA. CACAO (BUTTER OF). SEE BUTTER. * 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 grayish- white. It is not fusible before the blow- pipe. Its sp. grav. is about 2.2. It is found in detached masses on the river Cach in Bucharia, in the trap-rocks of Iceland, in Greenland and the Ferroe Islands. Accord- ing to Brongniart, 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 disco- vered by M. Stromeyer, in the autumn of 1817, in some carbonate of zinc which he CAD CAD was examining in Hanover. It has been since found in the Derbyshire silicates of zinc. The following is Dr. Wollaston's pro- cess for procuring Cadmium. It is distin- guished by the usual elegance and preci- sion of the analytical methods of this phi- losopher. From the solution of the salt of zinc supposed to contain cadmium, pre- cipitate all the other metallic impurities by iron; filter and immerse 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 character on the application of the proper tests. Mr. Stromeyer's process consists in dis- solving the substance which contains cad- mium in sulphuric acid, and passing through the acidulous solution a current of sulphuretted hydrogen gas. He washes this precipitate, dissolves it in concentra- ted 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 ex- cess is added, to redissolve the zinc and the copper that may have been precipita- ted by the sulphuretted 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 lampblack, and expos- ing 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 gray, ap- proaching much to that of tin, which me- tal it resembles in lustre and susceptibility of polish. Its texture is compact, and its fracture hackly. It crystallizes easily in octohedrons, and presents on its surface, when cooling, the appearance 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 malleable, but when long hammered, it scales off in dif- ferent places. Its sp. grav. before hammer- ing, 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 sul- phuric, 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 appear- ance according to circumstances, from a brownish-yellow to a dark brown, and even a blackish colour. With charcoal it is re- duced 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 gelatinous hydrate. With the acides 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 add- ed in excess, they do not redissolve the precipitate, as is the case with the oxide of zinc. 2. Ammonia likewise precipitates the ox- ide white, and doubtless in the state of hy- drate; but an excess of the alkali immedi- ately redissolves 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 excess of this solution. Zinc exhibits quite different properties. 4. Phosphate of soda exhibits a white pulverulent precipitate. The precipitate formed by the same salt in solutions of zinc, is in fine crystalline plates. 5. Sulphuretted hydrogen gas, and the hydrosulphurets, precipitate cadmium yel- low or orange. This precipitate resembles orpiment a little in colour, with which it might be confounded without sufficient at- tention. But it may be distinguished by be- ing more pulverulent, and precipitating more rapidly. It differs particularly in its easy solubility muriatic acid, and in its fixity. 6. Ferroprussiate of potash precipitates solutions 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. CAD CAF 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 rectan- gular transparent prisms, similar to sulphate of zinc, and very soluble in water. It efflo- resces in the air. At a strong red heat it gives out a portion of its acid, and becomes a subsulphate, which crystallizes i plates that dissolve with difficulty in water. The neutral sulphate consists of, Acid, 1UO.OO 38.3 5.000 Oxide, 161.12 61.7 8.056 100 parts of the salt takes 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 23.31 water f 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 under a red heat, loses its water of crystallization, 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 transpa- rency, and falls down in a white powder. 100 .parts effused chloride are composed of, Cadmium, 61.39 7.076 Chlorine, 38.61 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 oxa- late is insoluble. The citrate f9rms a crys- talline powder, very little soluble. 100 parts of cadmium unite with 28.172 of sulphur, to form a sulphuret of a yellow co- lour, with a shade of orange. It is very fixed in the h're. It melts at a white-red heat, and on cooling, crystallizes in micaceous plates of the finest lemon-yellow colour. The sul- phuret dissolves even cold in cowcentrated muriatic acid, with the disengagement of sulphuretted hydrogen gas; but the dilute acid has little effect on it, even with the as- sistance of heat. It is best formed by heat- ing together a mixture of sulphur with the oxide, or by precipitating a salt of cadmium with sulphuretted hydrogen. It promises to be useful in painting. VOL. I. Phosphuret of cadmium, made by fusing the ingredients together, has a gray colour, and a lustre feebly metallic. Muriatic acid decomposes it, evolving phosphuretted hy- drogen 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, trans- parent, and not altered by exposure to air. Their lustre is pearly, approaching to me- tallic. It melts with extreme facility, and as- sumes, on cooling, the original form. At a high temperature, it is resolved into cadmi- um and iodine. Water and alcohol dissolve it with facility. It is composed of, Cadmium, 100.00 8.000 Iodine, 227.43 18.1984? 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 cad- mium is white, with a slight tinge of yellow. Its texture is composed of very fine plates. - 1 - of cadmium communicates a good deal 300 of brittleness to copper. At a strong heat the cadmium flies off. Tutty usually con- tains oxide of cadmium. The alloy con- sists of, opper, 100. Cadmium, 84.2 The alloy of cobalt and cadmium lias 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 granu- lar texture, which may be crvstallized in oc- tohedrons. Its specific gravity is greater than that of mercury! It fuses at 167 F. It consists of, Mercury, 100. Cadmium, 27.78 Dr. Clarke found in 100 gr. of the fibrous silicate of zinc, of Derbyshire, about of a grain of sulphuret of cadmium, a result which agrees with the experiments of Dr. Wollaston and Mr. Children.* *CAFFEIN. 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 precipi- tate 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 pleasant 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 gelatin occasions no precipitate with it,* CAL CAL CAJEPTTT On. The volatile oil obtained from the leaves of the cajeput tree. Caje- puta officinarum, the Melaleuca Leucaden- dron of Linnaeus. The tree which furnishes the cajeput oil is frequent on the mountains 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 reen colour, very limpid, lighter than water, of a strong smell, resembling camphor, and a strong pungent taste, like that of cardamons. It burns entirely away, without leaving any residuum. 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. CALCAUKOUS EAHTH. See LIME. * CALCAnix>uB SPATI. Crystallized carbo- nate of lime. It occurs crystallized in more than 600 different forms, all having for their 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 va- rieties 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 culc-spar are gray, yellow, red, green, and rarely blue. Vitreous lustre. Foliated fracture, with a threefold cleavage. Fragments rhomboidal. Transparent, or translucent. The transpa- rent 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 effervesces powerfully with acids. Some varieties are phosphorescent on hot coals It is found in veins in all rocks, from granite to alluvial strata, and some- times in strata between the beds of calcare- ous mountains. The rarest and most beau- tiful crystals are found in Derbyshire, 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, cliry- sopruse, plasma, onyx, sard, and sardonyx. Common calcedony occurs in various shades of white, gray, yellow, brown, green, and blue. The blackish-brown appears, on looking through the mineral, to become a blood-red. It is found in nodules; botryoidal, staiactitical, bearing organic impressions, in I'eins, and also massive. Its fracture is even, sometimes 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 mi- nute portion of water. Very fine stulactiti- al specimens have been found in Trevascus mine in Cornwall. It occurs in the toad- stone of Derbyshire, in the trap rocks of Fifeshire, of the Pentland-hills, Mull, Rum, Sky, and others of the Scotish Hebrides; likewise in Iceland, and the Ferro Islands. See the sub-species, under their respective titles * * CALC SIXTEH. Staiactitical carbonate of lime. It is found in pendulous conical rods or tubes, mamellated, mussive, ana in many imitative shapes. Fracture lamellar, or di- vergent fibrous. Lustre silky or pearly. Colours white, of various shades, yellow, brown, rarely green, passing into blue or red. Translucent semihard Aery brittle. Large stalactites are found in the grotto of Antiparos, the woodman's cave in the Hartz, the cave of Auxelle in France, in the cave of Castleton in Derbyshire, and Macalister cave in Sky. They are continually forming by the infiltration of carbonated l-me-water, through the crevices of the roofs of caverns. Solid masses of stalactite have been called oriental alabaster. The irregular masses on the bottoms of caves have been called stal- agmites.* * CALCHANTUM. Pliny's term for copperas.* 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 consider- ed with regard to these residues, is termed calcination. In this general way it has like- wise been applied to bodies not really com- bustible, 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 bo- rax, 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 concerning 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 chang- ing into the earth with the absorption of oxygen gas. When the amalgam of cal- cium is thrown into water, hydrogen gas is disengaged, and the water becomes a solu- tion of lime. From the quantity of hydro- gen evolved, compared with the quantity of hme formed in experiments of this kind, CAL CAL 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 become pot- ash, while a dark gray substance of metallic splendour, which is calcium, either wholly or partially deprived of oxygen, is found im- bedded in the potash, for it effervesces vio- lently, and forms a solution of lime by the action of water. Lime is usually obtained for chemical purposes, from marble of the whitest kind, or from calcareous spar, by long exposure to a strong red heat. It is a soft white sub- stance, 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 so- luble in 450 parts of water, according to Sir H. Davy; and in 760 parts, according to other chemists. The solubility is not in- creased 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 phenome- non called slaking. The heat proceeds, ac- cording to Dr. Black's explanation, from the consolidation of the liquid water into the lime, forming a hydrate, as slaked lime is now called. It is a compound of 3.56 parts of lime, with 1.125 of water; or very nearly 3 to 1. This water may be expelled by a red heat, and therefore does not adhere to lime with the same energy as it does to ba- rytes and strontites. Lime water is astrin- gent 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 exposed to the air, it gradually attracts car- bonic acid, and becomes an insoluble carbo- nate, while the water remains pure. If lime water be placed in a capsule under an exhausted receiver, 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 pro- portion in which it combines with oxygen, to form lime; but his results can be regard- ed only as approximations, in consequence of the difficulties of the experiment. The prime equivalent of lime, or oxide of cal- cium, can be determined to rigid precision, by my instrument for analyzing the carbo- nates. Ry this means, I find, that 100 parts of carbonate of lime, consist of 43.60 carbonic acid -f- 56.4 lime; whence the prime equivalent proportions are, 2.75 acid 4- 3.562 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, 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- 3.56 lime; but it has not been exactly anal} zed. When thrown into water, phosphuretted hydrogen gas is disengaged in small bubbles,' which explode in 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 hydrogurei ted sulphuret of lime is immediately tormed. 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 sulphu- ret of lime probably consists of 2. sulphur + 3.56 lime. 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 ignit- ed, it forms the same substance, or chloride of calcium. It is a semitransparent crystalline substance; fusible at a strong red heat; a non- conductor of electricity; has a very bitter taste; rapidly absorbs water from the atmosphere ; and is extremely soluble in water. (See MU- RIATIC ACID). It consists of 2.56 calcium -f- 4.45 chlorine = 7.01. 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. Several years ago I performed a series of laborious, and rather insalubrious experi- ments, synthetical and analytical, on chlo- ride of lime; the results of some of which were detailed in a manuscript essay on alka- limetry, and other subjects connected with bleaching, submitted to Dr. Henry in 1816. Having since then been occupied in extend- ing my new methods of chemical research, I have delayed publishing till my plans shall be completed. Meanwhile I shall ob- serve, that slaked lime absorbs chlorine very greedily, though unslaked lime, at ordinary temperatures, condenses scarcely an appre- ciable quantity of the dry gas. Under a very trifling pressure, hydrate of lime is ca- pable of condensing almost its own weight of chlorine; or 3.56 lime -f 1.125 water = 4.685, combine with 4.45 chlorine. Hence, it is really a chloride of lime, and not a sub-bichlsride, as Dr. Thomson and JMr. Dalton have hastily inferred from con** CAL CAL mercial samples, altered by carriage and keeping 1 . And indeed, as it is not the in- terest of the manufacturer to make so rich and pure a compound, when he can get the market price for what contains only one- third or one-fourth the quantity of chlorine, it is absurd to assume a commercial article as the just chemical standard, or equivalent combination. In my first set of experi- ments, I took a certain weight of pure lime, sluiced it, and saturated it with pure chlofine. 1 next ascertained, by analysis, the propor- tion of lime, water, and chlorine, that exist- ed in the compound. The synthesis and analysis agreed very well. But the chloride slowly changes its nature from the disen- gagement of oxygen, by the superior affinity of the chlorine for the calcium. Hence, as well as from negligence or fraud in the ma- nufacture, the chloride of lime is always mixed with more or less of the common muriate. For this reason, as well as for that assigned by M. Gay-Lussac, in his ju- dicious critique on Dr. Thomson's paper on oxy muriate of lime, it is impossible to infer the bleaching power, or to analyze it, by using nitrate of silver. This test shows ttroflgvii in fact, when the power is weakest, or when the oxymuriate has passed into common muriate, to use the manufacturer's language. Nor is it possible to analyze the chloride with any precision, by exposing it to heat and measuring the oxygen expelled; because variable portions of chlorine are se- parated at the same time, in very uncertain states of combination. It is difficult to con- ceive how a chemist of Dr. Thomson's high reputation, should ever have pitched upon nitrate of silver to analyze the mingled chlo- rides of lime and calcium. In performing the synthetic experiment, the hydrate of lime must be kept cool, otherwise the heat produced by the chemical union, is very apt to expel oxygen from the lime, and generate some chloride of calcium. Mr. Dalton advises the use of solution of copperas, to analyze the bleaching powder. He desires us to add it, till all the chlorine smell disappears, and to measure the quan- tity of copperas employed. I tried this me- thod, and was nearly killed by it. The re- peated and careful application of the nostrils to the mixture, and the inevitable inhalation of chlorine, evolved by the sulphate ofiron, brought on a very painful and dangerous affection of the lungs. There is usually a considerable quantity of unsaturated lime in the above powder; the amount of which is readily ascertained by digesting it in water, and filtering. It may be expected, that 1 should HOW give my own method of analysis; but the desire of ve- rifying it by some further experiments of a new kind tor which I have hitherto wanted leisure, induces me to suppress it for the present. Ujider LJLME, gome observations will be found on the uses of this sub- stance. If the liquid hydriodate of lime be eva- porated to dry ness, and gently heated, an iodide of calcium remains. It has not been applied to any use.* * CALCTUFF. An alluvial formation of car- bonate of lime, probably deposited from ral- careous springs. It has a yellowish -gray co- lour; a dull lustre internally; a fine grained earthy fracture; is opaque, and usually mark- ed with impressions of vegetable matter. Its specific gravity is nearly the same with that of water. It is soft, and easily cut or bro- ken.* * CALCULUS, or STONE. This name is ge- nerally 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 observa- tion concerning the uric or lithic acid, all the discoveries relating to urinary concre- tions are due to Dr. \VoIlaston; discoveries so curious and important, as alone are suffi- cient to entitle him to the admiration and gratitude of mankind. They have been fully verified by the subsequent researches of MM. Fourcroy, Vauquelin, and Urande, Drs. Henry, Marcet, and Prout. Dr. Marcet, in his late valuable essay on the chemical his- tory and medical treatment of calculous dis- orders, 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 oxide 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 se- parable 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 strati- fied, and tinged by the secretion of the pros- tate gland, To the above Dr. Mai-cet 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 en evaporating its nitric aud solution, and is CAL CAL composed of laminae. But the cystic oxide is not laminated, and it leaves a white resi- duum from the nitric acid solution. Though they are both soluble in acids as well as al- kalis, 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. Maroet's other new calculus, was found to possess the properties of the fibrin of the blood, of which it seems to be a depo- site. He terms itjibrinous calculus. Species I. Uric acid calculi. Dr Henry says, in his instructive paper on urinary and other morbid concretions, read before the Medical Society of London, March 2, 1819, that it has never yet occurred to him to exa- mine calculi composed of this acid in a state of absolute purity. They contain about 9-10ths of the pure acid, along with urea, and an animal matter which is not gelatin, but of an albuminous nature. This must not, however, be regarded as a cement. The calculus is aggregated by the cohesive attrac- tion 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 sur- face, a lamellar or radiated structure, and consist of fine particles well compacted. Their sp. gravity varies from 1.3 to 1.8. They dissolve in alkaline lixivia, without evolving an ammoniacal odour, arid exhale the smell of horn before the blow-pipe. The relative frequency of lithic acid calculi will be seen from the following statement. Of 150 examined by Mr. Brunde, 16 were com- posed wholly of this acid, and almost all con- tained more or less of it. Fourcroy and Vauquelin found it in the greater number of 500 which they analyzed. All those exa- mined by Scheele consisted of it alone; and SOJ analyzed by Dr. Pearson, contained it in greater or smaller proportion. According to Dr. Henry's experience, it constitutes 10 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 phos- phate. This calculus is white like chalk, is friable between the fingers, is often covered with dog-tooth crystals, and contains semi- orystalline layers. It is insoluble in alkalis, but soluble in nitric, muriatic, and acetic acids According to Dr. Henry, the earthy phosphates, comprehending the 2d and 3d species, were to the whole number of con- cretions, in the ratio of 10 to 85. Mr. Brande justly observes, in the 16tli number of his Journal, that the urine lias at all times a tendency to depositethe triple phosphate, upon any body over which it passer. 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 shod: time become considerably enlarged by depo- sition of the same substance. When this calculus, or those incrusted with its semi- crystalline particles are strongly heated be- fore 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. Cal- culi composed entirely of the ammonia-mag- nesian 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 calculus has a brilliant white colour, a faint sweetish taste, and is somewhat soluble in water. Four- croy and Vauquelin suppose the above depo- sites to result from incipient putrefaction of urine in the bladder. It is certain that the triple phosphate is copiously precipitated from urine in such circumstances out of the body. Species 3. The bone earth calculus. Its surface according to Dr. Wollaston, is ge- nerally 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 tuse this calculus by the blow- pipe, but it dissolves readily in dilute mu- riatic acid, from which it is precipitable by ammonia. This species, as described by Fourcroy and Vauquelin, 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 inti- mately mixed with a gelatinous matter, which is left in a membranous 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 phos- phate of lime, in any of the collections 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-magne- sian 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 a 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 hthic 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 perform- ed by distilled vinegar, w r hich at a gentle heat dissolves the ammonia-magnesian phos- CAL CAL phate, 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 solubility in the water of pure potash or soda. Or the lithic acid may, in the first instance, be re- moved by the alkali, which expels the am- monia, and leaves the phosphate of magne- sia and lime. Species 5. The mulberry calculus. Its surface is rough and tuberculated; Colour deep reddish-brown. Sometimes it is pale brown, of a crytalline texture, and covered with flat octohedral crystals. This calculus has commonly the density and hardness of ivory, a sp. grav. from 1.4 to 1.98, and ex- hales the odour of semen when sawed. A moderate red heat 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 grayish-brown colour, composed of small co- hering 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 blow-pipe. Mulberry calculi contain always an admix- ture of other substances besides oxalate of lime. These are, uric acid, phosphate of lime, and animal matter in dark flocculi. The colouring matter of these calculi is pro- bably 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 pecu- liar greasy lustre. Its usual colour is pale brown, bordering on straw-yellow; and its texture is irregularly crystalline. It unites in solution with acids and alkalis, crystal- lizing 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 decomposed by heat into carbonate of ammonia and oil, leaving a minute residuum of phosphate of lime. This concretion is of very rare occurrence. Dr. Henry states its frequency to the whole, as 10 to 985. In two which he examined, the nucleus was the same substance with the rest of the concretion; and in a third, the mucleus 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 ge- nerated in the bladder. It might be called with propriety renal oxide, if its eminent discover shouJd think fit. Species 7. The alternating calculus. The surface of this calculus is usually white like chalk, and friable or semi-crystalline, accord- ing as the exterior coat is the calcareous or ammonia-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 commoa alternating calculi; next are those of oxa- late of lime with phosphates; then oxalate of lime with lithic acid; and lastly, those in which the three substances alternate. The alternating, tak.n all together, occur in 10 out of 25, in Dr. Henry's list; the lithic acid with phosphates as 10 to 48 ; the oxa- late of lime with phosphates, as 10 to 116; 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. This consists of a mixture of lithic acid with the phosphates in variable proportions, and is consequently variable in its appearance. Sometimes the alternating layers are so thin as to be undistinguishable by the eye, when their nature can be determined only by che- mical analysis. This species, in Dr. Henry's list, forms 10 in 235. About l-40th of the calculi examined by Fourcroy and Vauque- lin were compjound. Species 9. has been already described. In almost all calculi, a central nucleus may be discovered, sufficiently small to have descended through the ureters into the bladder. The disease of stone is to be considered, therefore, essentially and ori- ginally as belonging to the kidneys. Its in- crease in the bladder may be occasioned, either by exposure to urine that contains an excess of the same ingredient as that com- posing the nucleus, in which case it will be unifomrly constituted throughout; or if the morbid nucleus deposite should cease, the concretion will then acquire a coating of the earthy phosphates. It becomes, therefore, highly important to ascertain 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 extra- neous substances; and in 3 the nucleus was replaced by a small cavity, occasioned pro- bably by the shrinking of some animal mat- ter, round which the ingredients of the cal- culi (fusible) had been deposited. Ran has- shown by experiment, that pus may form the nucleus of an urinary concretion. The re- maining 158 calculi of Dr. Henry's list, had central nuclei composed chiefly oftithic acid. It appears also, that in a very great majority of the cases referred to by him, the disposi- tion to secrete an excess of lithie acid has been the essential cause of the origin of stone. Hence it becomes a matter of great CAL CAL importance to inquire, what are the circum- stances which contribute to its ( xcessive 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 species, consisting of, 20 phosphate of lime 60 ammonia-magnesian phosphate JO lithic acid 10 animal matter 100 In some instances, though these are com- paratively very few, a morbid secretion of the earthy phosphates in excess, is the cause of the formation of stone. Dr. Henry re- lates the case of a gentleman, who, during parox\sms of gravel, preceded by severe sickness and vomiting, voided urine as opaque as milk, which deposited a great quantity of an impalpable powder, consist- ing 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 abstrac- tion of the earth of his bones; for there was no emaciation of the muscles corresponding to the above diminution. The first rational views on the treatment of calculous disorders, were given by Dr. "Wollaston. These 1m e been followed up lately by some very judicious observations of Mr. Brande, in the 12th, 15th, aud 16th numbers of his Journal; and also by Dr. Marcet, in his excellent treatise already re- ferred to. Of the many substances con- tained in human urine, there are rarely more than three which constitute gravel; viz. calcareous phosphate, ammonia-magne- sian phosphate, and lithic acid. The for- mer 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 heid in solution, whatever disorder of the system, or impropriety of food and medicine, diminishes that acid excess, favours the for- mation of white deposite. The internal use of acids was shown by Dr. Wollaston, to be the appropriate remedy in this case. White gravel is frequently symptomatic of disordered digestion, arising from excess in eating or drinking; and it is often pro- duced by too farinaceous a diet. It is also occasioned by the indiscreet use of magnesia, sociu water, or alkaline medicines in general. Medical practitioners, as well as their pa- tients, ignorant of chemistry, have often committed fatal mistakes, by considering the white gravel, passed on the administra- tion of alkaline medicines, as the dissolution of the calculus itself; and have hence push- -ed a practice, which has rapidly increased the size of the stone. Magnesia, in many cases, acts more injuriously than alkali, in precipitating 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 obtained the latter acid, by placing urine under an exhausted receiver; and he has formed carbonate of barytes, by dropping barytes water into urine re- cently 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 follows meals, and if it be ob- served in the urine, not as a mere deposite, but at the time the last drops are voided, it becomes a matter ot importance, as the fore- runner of other and serious forms of the dis order. It has been sometimes viewed as the effect of irritable bladder, where it was in reality the cause. Acids are the proper remed} , and unless some peculiar tonic effect be sought for in sulphuric acid, the vegeta- ble 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 re- turning from warm climates, with dyspeptic and hepatic disorders, often void this white gravel, for which they have recourse to em- pyrical solvents, for the most part alkaline, and are deeply 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 cyder, champagne or claret, but the less of these fermented liquors the better. An effervescing draught is often very bene- ficial, made by dissolving 30 grains of bi- carbonate of potash, and 20 of citric acid, in separate tea cups of water, mixing the solu- tion in a large tumbler, and drinking the whole during the effervescence. This dose may be repeated 3 or 4 times a-day. The car- bonic acid of the above medicine enters the circulation, and passing off by 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 fre- quently attended by an apparently formida- ble 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 tonics, are in like manner often successful in removing the urinary complaints of grown up persons. In considering the red gravel, it is neces- sary 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 appearance is an alarming in- CAL CAL dication of a tendency to form calculi; in the second, it is often merely a fleeting symp- tom of indigestion. Should it frequently re- cur, however, it is not to be disregarded. Bicarbonate of potash or soda is the pro- per remedy for the red sancL or lithic acid deposite. The alkali may often be benefi- cially combined with opium Ammonia, or its crystallized carbonate, may be resorted to with advantage, where symptoms of indiges- tion 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 dis- agree with the stomach, to create nausea, 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 danger- ous quantities in the intestines, and to form a white sediment in urine, calls on the prac- titioner to look minutely after its adminis- tration. It should be occasionally alternatrd "With other laxative medicines. Magnesia dissolved in carbonic 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 alkaline medicines too far, lest they give rise to the deposition of earthy phosphates in the urine. Cases occur in which the sabulous depo- site consists of a mixture of lithic acid with the phosphates. The sediment of urine in inflammatory disorders is sometimes of this nature; and of those persons who habitually indulge in excess of wine; and also of those who, labouring under hepatic affections, se- crete much albumen in their urine. Purges, tonics, and nitric acid, which is the solvent f both the above sabulous matters, are the appropriate remedies. The best diet for pa- tients labouring under the lithic deposite, is a vegetable. Dr. Wollaston's fine observa- tion, that the excrement of birds fed solely upon animal matter, is in a great measure lithic acid, and the curious fact since ascer- tained, that the excrement of the boa con- strictor, fed also entirely on animals, is pure lithic acid, concur in giving force to the above dietetic prescription. A week's ab- stinence 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 vegetable system so far as to produce flatulency and indigestion. Such are the principal circumstances con- nected with the disease of gravel in its inci- pient or sabulous state. The calculi formed in the kidneys are, as we have said above, either lithic, oxalic, or cystic; and very rare- ly indeed of the phosphate species. An aqueous regimen, moderate exercise on horseback when not accompanied with much irritation, cold bathing, and mild aperients, along with the appropriate chemical medi- cines, must be prescribed in kidney cases. These are particularly requisite immediately after acute pain in the region of the ureter, and inflammatory symptoms have led to the belief that a nucleus lias descended into the bladder. Purges, diuretics, and diluents, ought to be liberally enjoined. A large quantity of mucus streaked with blood, or of a purulent aspect, and iiaemorrhagy, are frequent symptoms ot the passage of the stone into the bladder When a stone has once lodged in the bladder, and increased there to such a size as no longer to be capable of passing thro; ,;h 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 although ic is possible that it may become so loosened in its texture, as to be voided piecemeal, 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 endea- vours must therefore be directed towards re- ducing the excess of lithic acid in the urine to its natural standard; or, on tiie other hand, to lessen the tendency to the deposition of the phosphates. The urine must be sub- mitted to chemical examination, and a suit- able course of diet and medicines prescribed. But the chemical remedies must be regu- lated nicely, so as to hit the happy equili- brium, in which no deposite will be formed. Here is a powerful call on the physicians and surgeons to make themselves thoroughly versant m chemical science; for they will otherwise commit the most dangerous blun- ders 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 refuta- tion." In respect to the phosphates, it seems possible, by keeping up an unusual acidity in the urine, so tar to soften a crust of the calculus, as to make it crumble down, or ad- mit of being abraded by the sound; but this is the utmost that can be looked for; and the lithic nucleus will still remain. 1'hese considerations," adds Mr. Brande, " inde- pendent 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 alkalis, if sufficiently strong to act upon the uric crust of the calculus, they would certainly injure the coats of the bladder; thev 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 CAL CAL Foiircroy, and others who have advised the J>lan of injection, 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." Jvurnal of Science, vol. vii, p. 216. 1 have judged it an imperative duty to in- sert the above cautions, from an eminent chemist who has studied this subject in its medical relations, lest the medical student, misled by Dr. Thomson's favourable tran- script of the injection scheme, might be hur- ried into very dangerous practice. ft 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 m gravel of the vinum c'ilchi- <"/, the specific for gout. Bv a note to Mr. Brando's dissertution we learn, that benefit has bten derived 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 consis* of uric acid, after it has at- tained considerable size in the bladder; all that can be effected under such circum- stances by alkaline medicines appears, as Mr. Brande has remarked, to be the precipitating upon it a coating of the earthy phosphates from the 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 inference may be drawn also from the dissections of those persons in whom a stone was supposed to be dissolved by al- kaline medicines; for in these instances it has been found either encysted, 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 princi- pally of the phosphates of lime and ammo- nia, with animal matter. Several taken from horses, were of a similar composition. One of a rabbit consisted chiefly of carbo- nate of lime and animal matter, with perhaps a little phosphoric acid. A quantity of sabu- lous matter, neither crystallized nor con- crete, is sometimes found in the bladder of the horse: in one instance there were nearly 45 pounds. These appear to consist of car- bonate of lime and animal matter. A cal- culus of a cat gave Fourcroy three parts of carbonate, and one of phosphate of lime. That of a pig, according to Bertholdi, 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 fftflnd 3 parts of car- VOL. I. bonate, and one of phosphate of lime. Dir,. Pearson, in one instance, carbonate of lime, and animal matter; in two others, phos- phates 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 sup- posed that they were phosphate of lime; but Dr. Wollaston has shown, that they are lithate of soda. The calculi found some- times in the pineal, prostate, salivary, and bronchial glands, in the pancreas, in the cor- pora cavernosa penis, and between the mus- cles, as well as the tartar, as it is called, that encrusts the teeth, appear to be phosphate of lime. Dr. Grompton, however, examined a calculus taken from the lungs of a de- ceased 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 circumfer- ence. For the biliary calculi, see GALL. Those called bezoars have been already noticed un- der that article. . It has been observed, that the lithic acid, which constitutes the chief part of most hu- man urinary calculi, and abounds in the arth- ritic, has been found in no phytivorous ani- mal; and hence has been deduced a practi- cal inference, that abstinence from animal food would prevent their formation. But we are inclined to think this conclusion too has- ty. 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 prac- tical inference is sanctioned by the most re- spectable medical authorities. Ox CALOUIC. By Dr. Ure. * CALORIC. The Agent to which the phe- nomena of heat and combustion are ascribed. This is hypothetically regarded as a fluid, of inappreciable tenuity, whose particles are endowed with indefinite idio-repulsive pow- ers, and which by their distribution in various proportions among the particles of pondera- ble matter, modify cohesive attraction, giv- ing birth to the three general forms of ga- seous, liquid, and solid. Many eminent philosophers, however, have doubted the separate entity of a calorific mat- ter, and have adduced evidence to show that the^hejiomena might be rather referred to a vibratory or intestinal motion of the par- ticles of common matter. The most distin- guished advocate of this opinion in modern times is Sir H. Davy, the usual justness ami 28 CAL CAL profundity of whose views entitle them to deference. The following sketch of his ideas on this intricate subject, though it graduates perhaps info the poetry of science, cannot jail 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 1 a subtile fluid capable of combining with bodies, and of separating their parts from each other, which ha been named the matter of heat or caloric- " Many of the phenomena admit of a hap- py explanation on this idea, such as the cold produced during the conversion of solids into fluids or gases, and the increase of tem- perature connected with the condensation of gases and fluids." In the former case we say the matter of heat is absorbed or com- bined; ii\ the latter it is extruded or disen- gaged from combination. " But there are ether 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 protoxide 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 se- cond 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 percussion, which is recovered in the fire; but this is a very rude mechanical idea: the arrangements of its parts are altered by hammering in this way, and it is rendered brittle. By a moderate degree of friction, as would appear from Rumford's experi- ments, 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 inexhaust- ible. 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 inust have separated" from each other. The immediate cause of the phenomena of heat, then, is motion, and the laws of its commu- nication are precisely the same as the bjws of the communication of motion." Since all matter may be made to fill a smaller volume by cooling, it is evident that the particles of ^flatter must have space between themj and since every body can communicate the pow- er of expansion to a body of a lower tempe- rature, that is, can give" an expansive mo- tion to its particles, it is a probable infer- ence that its own particles are possessed of motion; but as there is no change in the po- sition of its parts as long as its temperature is uniform, the motion, if it exist, must be a vibratory or undulatory motion, or a motion of the particles round their axes, or a mo- tion 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 li- quids 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 sub- stances," the particles move round their own axes, and separate from each other, penet ra- ting in right lines through space. Tempe- rature maybe conceived to depend upon the velocities of the vibrations; increase of capa- city on the motion being performed in great- er space ;and the diminution of temperature, during the conversion of solids into flu ids or gases, may be explained on the idea of (he loss of vibratory motion, in consequence of the revolution of particles round their axes, at the moment when the body becomes li- quid or aeriform; or from the Joss of rapidi- ty of vibration, in consequence of the mo- tion 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 mat- ter 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 pass- ing 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 expe- riments have been made, which show that bodies, when heated, do not increase in weight. This, as far as it goes, is an evi- dence against a subtile elastic fluid, produc- ing the calorific expansion; but it cannot be considered as decisive, on account of the im- perfection of our instruments. A cubical inch of inflammable air requires a good ba- lance to ascertain that it has any sensible weight, and a substance bearing the same re- lation to this, that this bears to platinum, could not perhaps be weighed by any method in our possession."! fThis view of the subject is to me unsa- tisfactory. It Is true that the idea of hc* CAL CAL 1$. has been supposed, on the other hand, son the calorific rays which accompany those that the observations of Sir Wm. Herschel of light in the solar beam, afford decisive being- motion, is sanctioned by Newton, as well as by the illustrious chemist above named. But the former adopted his opinion at a time, when the existence of heat in a latent state was as yet unsuspected, and when many phenomena unfavourable to the notion he suggested were unknown. It is fully established in mechanics, that when a body in motion is blended with and thus made to communicate motion to another body, previously at rest, or moving slower, the velocity of the compound mass after the impact will be found, by multiplying 1 the weight of each body, by its respective ve- locity, and dividing the sum of the products, by the aggregate weight of both bodies. Of course it will be more than a mean or less than a mean, accordingly as the quicker body was lighter or heavier than the other. Now according to Sir Humphrey Davy, the particles of substances which are unequally heated are moving with unequal degrees of velocity; of course when they are reduced by contact to a common temperature, the heat, or what is the same (in his view), the velocity of the movements of their particles, ought to be found by multiplying 1 the heat of each by its weight and dividing the sum of the product by the aggregate weight. Hence if equal weights of matter be mixed, the temperature ought to be a mean; and if equal bulks, it ought to be as much nearer the previous temperature of the heavier substance as the weight of the latter is greater; but the opposite is in most in- stances true. When equiponderant quanti- ties of mercury and water are mixed at different temperatures, the result is such as might be expected from the mixture of the water, were it three times heavier;, so much nearer to the previous heat of the water, is the consequent temperature. It may be said that this motion is not measurable upon mechanical principles. How then, I ask does it produce mechanical effects? These must be produced by the force of the vibrations, which are by the hypothesis mechanical: for whatever laws hold good in relation to mov- ing matter in mass-, must operate in regard to each particle of that matter; the effect of the former, can only be a multiple of that of the latter. Indeed, one of Sir Hum- phrey Davy's reasons for thinking heat to consist of corpuscular motions is that me- chanical attrition generates it. Surely tlien a motion, produced by mechanical means, and which produces mechanical effects, may be estimated on- mechanical principles. In the case cited above, the power of re- ciprocal communication of heat in two fluids, is shown to be inconsistent with the views of this ingenious theorist. If we compare the same jjovrcr in solids, the result will be equally objectionable. Thus the heating power of glass being 443, that of an equal bulk of lead will be 487, though so many times heavier; and if equal weights be com- pared, the effect of the glass, will be four times greater than that of the lead. If it be said, that the movements of the.tlenser mat- ter are made in less space and therefore re- quire less motion, I answer that if they be made with equal velocity, they must go through equal space in the same time, their alternations* being more frequent. And if they be not made with the same velocity, they could not communicate to matter of a lighter kind, a heat equally greats since agreeably to experience no superiority of weight will enable a body, acting di- rectly on another to produce in it a niotioQ quicker than its own. Consistently with this doctrine, the particles of an aeriform fluid, when they oppose a mechanical resistance, do it by aid of a certain movement, which causes them effectively to occupy a greater space than when at rest. It is true, a body, by moving backwards and forwards, may keep off other bodies from the space in which it moves. Thus let a weight be par- tially counterbalanced by means of a scale beam, so that if left to itself it would de- scend gently. Place exactly under it another equally solid mass, on which the weight would fall if unobstructed. If between the two bodies thus situated, a third be caused to undergo an alternate motion, it may keep the upper weight from descending, pro- vided the force with which the latter de- scends, be no greater than that of the move- ment in the interposed mass, and the latter acts with such celerity, that between each stroke the time be too small for the weight to move any sensible distance. Here then we have a case analagous to that supposed, in which the alternate movements or vibra- tions of matter enable it to preserve to it- self a greater space in opposition to a force impressed; and it must be evident that length- ening or shortening the extent of the vibra- tions of the interposed body, provided they are made in the same time, will increase or diminish the space apparently occupied by it, as the volume of substances is aliected by an increase or reduction of heat. It ought however to be recollected that in the case we have imagined, there is a constant expenditure of momentum to compensate for that generated in the weight by gravity^ during each vibration. In the vibrations conceived to constitute heat, there is no generating power to make up for this loss, A body preserves the -expansion communi- cated by lu-at in -sacuo, where, insulated from all other matter, the only momentum, by whifh the vi brut ions- of its particles OA\ CAL CAL evidence of the materiality of caloric, or at least place the proof of its existence and that of liffht, on the same foundation. That cele- be supported, must liuve been received be- fore its being thus situated. If we pour mercury into a glass tube shaped li'ke a shepherd's crook, the hook being down- wards, the fluid will be prevented from oc- cupying that part of the tube where the air is in such position as not to escape. In this case, according to the hypothesis in question, the mercury is prevented from entering the space the air occupies, by a series of im- palpable gyratory movements; so that the collision of* tire aerial particles against each other, causes each to occupy a larger share of space in the manner above illustrated by the descending weight and interposed body. The analogy will be greater, if we suppose a row of interposed bo*dies alternately striking against each other, and the descending Wright; or we may imagine a vibration in all the particles of the interposed mass, equal in aggregate extent and force to that of the whole, \\hen performing' a con mon movement. If the aggregate extent of the vibration of the particles very much exceed that which when performed in mass would be necessary to preserve a certain space, it may be supposed productive of a substance like the air by which the mercury is re- sisted. But whence is the momentum ade- quate in such rare media to resist a pressure of a fluid so heavy as mercury, which in this case performs a part similar to that of the weight, cited for the purpose of illus- tration? If it be said that the mercury and glass being at the same temperature as the air, the particles of these substances vibrate in a manner to keep up the aerial pulsations; I ask, when the experiment is tried in an exhausted receiver, what is to supply mo- mentum to the mercury and glass? There is no small difficulty in conceiving under the most favourable circumstances, that a spe- cies of motion, that exists according to the hypothesis as the cruise of expansion in a heated solid, should cause a motion produc- tive of fluidity or vaporization, as when by means of a hot iron, we convert ice into water, and water into vapour. How inconceivable is it that the iron boikr of a steam engine should give to the particles of water, a motion s< totally differ- ent from any it can itself possess, and at the same time capable of such wonderful effects, as are produced by the agency of steam. Is it to be imagined that in particles whose weight does not exceed a few ounces, suffi- cient momentum can be accumulated to move as many tons? There appears to me another very serious obstacle to. this expla- nation of the nature of heat. How are we to account for its radiation in vacuo, which the distinguished advocate of the hypothesis brated astronomer discovered that when si- milar thermometers were placed in the dif- ferent parts of the solar beam, decomposed by the prism into the primitive colours, they indicated different temperatures. He esti- mates the power of heating iu 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 increase 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 II. Englefield with similar results. Mr. He- rard, however, came to a somewhat diffe- rent conclusion. To render his experiments more certain, and their effects more sensible, this ingenious philosopher availed himself of the heliostat, an instrument by which the sun- beam can be steadily directed to one spot during the whole of its diurnal period. He decomposed by a prism the sunbeam, re- flected from the mirror of the heliostat, and placed a sensible thermometer in each of the seven coloured rays. The calorific faculty was found to increase progressively from the violet to the red portion of the spectrum, in which the maximum heat existed, and not beyond it, in the unilluminated space. The greatest rise in the thermometer took place, while its bulb was still entirely covered by the last red rays; and it was observed pro- gressively to sink as the bulb entered into the dark." Finally, on placing the bulb quite has himself shown to ensue? There can be no motion without matter. To surmount this difficulty, he calls up a suggestion of Newton's, that the calorific vibrations of matter may send off radiant particles, which lose their own momentum in communicating vibrations to bodies remote from those, whence they emanate. Thus according to Sir Humphrey, there is radiant matter pro- ducing heat, and radiant matter producing light. Now, the only serious objection made by him to the doctrine which considers heat as material, will apply equally against the existence of material calorific emana- tions. That the cannon, heated by friction in the noted experiment of Kumford, would have radiated as well as if heated in any other way, there can, I think, be no doubt; and as well in vacuo, as the heat excited by Sir Humphrey in a similar situation. That its emission in this way would have been as inexhaustible as by the conducting pro- cess caimot be questioned. Why then is it not as easy to have an inexhaustible supply of heat as a material substance, as to have an inexhaustible supply of radiant matter, communicating the vibrations in which he represents heat to consist? CAL CAL e ex- plained by supposing them composed of par- ticles differing in size, the largest being at the red, and the smallest at the violet ex- tremity of the spectrum. The same great man has put the query, Whether light and Common matter are not convertible into each other? and adopting the idea that the phe- nomena of sensible heat depend upon vibra- tions of the particles of bodies, supposes that a certain intensity of vibrations may send off particles into free space; and that particles in rapid motion in right lines, in losing their own motion, may communicate a vibratory, motion to the particles of terrestrial bodies, In this way we can readily 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 Kttle room there is to pronounce dogmatic decisions on the abstract nature of heat. If the essence of the cause be still involved in mystery, many of its properties and effects ha've been ascertained, and skilfully applied to the cultivation of science and the uses of life.f | We see the same matter, at different times, rendered self-attractive, or self-repel- tent; now cohering in the solid form with great tenacity, and now flying apart with explosive violence in the state of vapour. Hence the existence, in nature, of two op- posite kinds ef reaction; between particles, is self evident. There can be no property, without matter, in which it may be inher- ent. Nothing can have no property. The question then is, whether these opposite properties can belong to the same particles. Js it not evident, that the same particles can- not, at the same time, be self-repellent, and sett-attractive? Suppose them to be so, one or the other must predominate, and in that Qase we should not perceive the existence of the other. It would be useless, and the particles would in effect, possess the predo- minant property alone, whether attraction or repulsion. If the properties were equal in power, they would annihilate each other, and the matter would be, as if void of ei- ther properly. There must, therefore, be a mutter, in which the* sett-rep ellciit power 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 existing in bodies in greater or smaller quan- tities, without meaning thereby to decide o the question 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 bo- dies, by being progressively heated, pro- resides, as well as matter in which attraction resides. There must also be as many kinds of mat- ter, as there are kinds of repulsion, of which the affinities, means of production, or laws of communication are different. Hence i do firmly believe in the existence of mate- rial fluids, severally producing the pheno- mena of heat, light and electricity. Sub- stances, endowed with attraction, make themselves known to us, by that species of this power, which we call gravitation, by which they are drawn towards the earth, and are therefore heavy and called ponde- rable; by their resistance to our bodies, pro- ducing the sensation of feeling or touch; and by the vibrations or movements in other matter, affecting the ear with sounds, and the eye by a modified reflection of light. Where we perceive none of these usual concomitants of matter, we are prone to in- fer its absence. Hence ignorant people have no idea of air, except in the state of wind, and when even in a quiescent state desig- nate it by this word. But that the princi- ples, the existence of which has been de~ monstrated, should not be thus perceived* is far from being a reason for doubting their existence. A very slight attention to their qualities will make it evident, that they could not produce any of the efiects, by which the existence of matter in its ordina- ry form is recognized. The self-repellent property renders it impossible that they should resist penetration; their deficiency oY weight, renders their momentum nugato- ry When in combination, they are not per- ceived, but the bodies with which they com- bine; and it is only by the changesthey pro- duce in such bodies, or their efiects upon our nerves, that thev can be clet??cted-. CAL CAL gyessively increase in bulk. On this princi- ple are constructed the various instruments for measuring temperature. If the body se- lected for indicating 1 , by its increase of bulk, the increase of heat, suffered equal expan- sions by equal increments of the calorific power, then the instrument would be per- fect, and we should have a just thermometer, or pyrometer. But it is very doubtful whe- ther any substance, solid, liquid, or aeriform, 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 1'ransactious for 1818, con- veys 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 en- largement by caloric. Each portion that enters into a body must weaken the antago- nist force, cohesion, and must therefore ren- der more efficacious the operation of the next portion that is introduced. Let 1000 represent the cohesive attraction at the com- mencement, then, after receiving one incre- ment of caloric, it will become 1000 1 = 999. Since the next unit of that divel- Jent agent will have to combat only this di- minished cohesive force, it will produce an effect greater than the first, in the propor- tion of 1000 to 999, and so on in continued progression. That the increasing ratio is, however, greatly less than Mr. Dulton main- tains, may, I think, be clearly demonstrated." 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 phi- losophical friends and pupils. By means of two admirable micrometer microscopes of Mr. Troughton's contraction, 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 correspond- ed pco'iprtssu with the indications of two mer cunal thermometers of singular nicety, made by Mr. Crighton ot Glasgow, one of which cost three guineas, and the other two, and they were 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 hy- pothetical graduation of thermometers. They were obtained and detailed in public lec- tures many years before the elaborate re- searches of Messrs. Petit and Dulong on the same Abject appeared; and indeed the pa- per itself passed through Dr. Thomson's hands, to London, many months before the excellent dissertation of the French philo- sophers was published. Their memoir gain- ed a well-merited prize, voted by the Aca- demy of Sciences, on the 16th of March 1818. My paper was submitted the preced- ing summer, in its finished state, to three professors of the University of Glasgow, as well as to Dr. Brewster and Dr. Murray. The researches of MM. Dulong and Petit are contained in the 7th volume of the Annales de Chimie et Physique. They commence with some historical details, in which they observe, " that Mr. Dalton, con- sidering this question from a point of view much more elevated, has endeavoured to establish general laws applicable to the mea- surement of all temperatures. These laws, it must be acknowledged, form an imposing whole by their regularity and simplicity. Unfortunately, this skilful philosopher pro- ceeded with too much rapidity to generalize his very ingenious notions, but which de- pended 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 1 and boiling water, a mercurial and air ther- mometer did not present any sensible dis- cordance. The following table of MM. Du- long and Petit gives the results from nearly the freezing- to the boiling point of mercury* TdBLE of Comparison of the Mercurial and Jtir Thermometer. Temperature indicated by the mercurial. Corresponding volt, of the same Temperature indicated by an air thermometer, corrected for the dilatation of glass. Centigr. Fahr. mass of air. Centigr. Fahr. 36 32.8 0.8650 36.00 328 4-32. 1.0000 0.00 + 32.0 100 212 1.3750 100.00 212.0 150 302 1.5576 148.70 299.66 200 392 1.7389 197.05 386.69 250 482 1.9189 245.05 47509 300 572 2. 76 292.70 558.86 Boiling,360 680 2.3125 350 00 662.00 CAL CAL The well known uniformity in the princi- pal physical properties of all the gases, and particularly the perfect identity in the laws of their dilatation, render it very probable, that in this class of bodies the disturbing 1 causes, to which I have adverted in my pa- per, 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 gast-s, are more immedi- ately dependent upon the force which pro- v in a masterly manner. CAL CAL "When a body cools in vacuo, its lieat 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 in that case added to that which is dissipated by radiation. It is natural therefore to distinguish these two effects; and as they are subject in all proba- bility to different laws, they ought to be separately studied. MM. Dulong and Petit employed fn 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 compari- sons 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 cooling between 60 and 50, and 40 and 30, was sensibly the same. On cooling water in 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 re- markable casualty, the contrary effect takes place in bodies heated to high temperatures, when the law of cooling in tin plate 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 bo- dies raised to high temperatures," say MM. Dulong and Petit, who terminate their preli- minary researches 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 follow- ing series was obtained when the balloon was surrounded with ice. The degrees are centigrade. Excess of the therm. Corresponding ve- abov e the balloon. locities of cooling. 2400 1Q69 220 8.81 200 7.40 180 6.10 160 4.89 140 3 88 120 3 o 100 2.30 80 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 ihc corresponding 1 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 Kichmann; for according to that law, the velocity of cooling at 2 1 CAL CAL cuo. This subtraction may be easily accom- plished now that we have a formula* which represents this velocity with great preci- sion, and for all possible cases. From numerous experimental compari- sons 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 temperature, on the density and tempera- ture 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 re- mains constant. If we call P the cooling power of air un- der the pressure p, this power will become P (1.366) under a pressure 2/v 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 = P //A0.45 v ~p i ' ^ e same for hydrogen, -p = \J j >o8 . 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 compare the law which we have thus announced," say MM. Dulong and Petit, *' with the approximations 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 calculations, and by the little precision attainable by the methods which they have followed." But for these discussions, we must refer to the memoir itself. The influence of the nature of the sur- face of bodies in the distribution of heat, was first accurately examined by Mr. Les- lie. This branch of the subject is usually called the radiation of caloric. To measure the amount of this influence with precision, he contrived a peculiar instrument, called a differential thermometer. 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 ther- mometers, and the bulbs have a diameter of l-3d of an inch and upwards. Before hermetically closing the instrument, a small portion of sulphuric acid, tinged with car- mine 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, requires dexterity in the operator. To this stem a scale divided into 100 parts VOL. I. is attached, and the instrument is then fixed upright by a little cement on a wooden sole. If the finger, or any body warmer than the ambient air, be ;>pp:iees, a "depends upon their the "Royal Society, that on clear and dewy specific gravity and specific heat conjunct- nights "he always found the mercury lower ly, and therefore must vary for each par- in a thermometer laid upon the ground, ticular substance. The mobility of the par- ticles in a fluid, and their reciprocal inde- pendence on one another, permit them to change their places whenever they are ex- panded or contracted by alternations of temperature; and hence the immediate and inevitable effect of communicating heat to in a meadow in his neighbourhood, than it was in a similar thermometer suspended in the air 6 feet above the former; and that upon one night the 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 2 feet above the sur- face, found in an hour afterwards, that the former stood 8 lower than the latter. He at first regarded this coldness of the sur the under stratum of a fluid mass, or of ab- stracting it from the upper stratum, is to determine a series of intestine movements. The colder particles, by their superior den- sity, descend in a perpetual current, and face to be the effect of the evaporation of force upwards those rarefied by the heat. the moisture, but subsequent observations and experiments convinced him, that the cold was not the effect, but the cause of deposition of dew. Undef a cloudless sky, the earth projects its heat without return, When however the upper stratum primari- ly acquires an elevated temperature,* it seems to have little power of imparting heat to the subjacent strata of fluid parti- cles. Water may be kept long in ebullition into empty space; but a canopy of cloud is a t the surface of a vessel, while the bottom a concave mirror, which restores the equi- librium by counter-radiation. See DEW. remains ice cold, provided we take mea- sures to prevent the heat passing down- On this" principle Professor Leslie has wards through the sides of the vessel itself constructed a pretty instrument, which he Count Rumford became so strongly per- calls JEthrioscope, whose function it is to suaded of the impossibility of communica- denote the clearness and coolness of the ting heat downwards through fluid parti sky. It consists of a polished metallic cup, cles, that he regarded them as utterly des of an oblong spheroidal shape; very like a titute of the faculty of transmitting that silver porter-cup, standing upright, with the power from one to another, and capable o1 1_ 11 / _ J'J3? A.' _ 1 Al. ., In ^s-isl .-' ' 1 ., 1-- * 1 1 1 bulb of a differential thermometer 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 acquiring heat, only in individual rotatior and directly, from a foreign source. The proposition thus absolutely announced if absurd, for we know that by intermixture and many other modes, fluid particles best form of the cup is an ellipsoid, whose part heat to each other; and experiment! eccentricity is equal to half the transverse ' axis, and the focus consequently placed at the third part of the whole height of the have been instituted, which prove the ac tual descent of heat through fluids by com munication from one stratum to another cavity; while the diameter of the thermos- But unquestionably this communication i cope ball should be nearly the third part of the orifice of the cup. A lid of the same thin metal unpolished, is fitted to the mouth of the cup, and removed only when an observation is to be made. The scale at- amazingly difficult and slow. We are henc< led to conceive, that it is an actual contac of particles, which in the solid conditioi facilitates the transmission of heat s< speedily from point to point through thei tached to the stem of the thermoscope, mass. This contact of certain poles in th may extend to 60 or 70 millesimal degrees above the zero, and about 15 degrees be- low it. This instrument exposed to the open air in clear weather, will at all times, both dur- ing the day and the night, " indicate an im- pression of cold shot downward from the higher regions," in the figurative language of the inventor. Yet the effect varies ex- ceedingly. It is greatest while the sky has the pure azure hue; it diminishes fast as the atmosphere becomes loaded with spreading clouds; and it is almost extinguished when low fogs settle on the surface. The liquid molecules, is perfectly consistent with voi< spaces, in which these molecules may slid< over each other in every direction; b; which movements or condensations, hea may be excited The fluid condition revert or averts the touching and cohering poles whence mobility results. This statemen may be viewed either as a representatio of facts, or an hypothesis to aid concep tion. Since the diffusion of heat through fluid mass is accomplished almost solel by the intestine currents, whatever ob structs these must obstruct the change c CAL CAL temperature. Hence fluids intermingled with porous matter, such as silk, wool, cot- ton, 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 heat- ed to the same degree, and exposed in similar covered vessels to the cool air. Of the conducting power of gaseous bodies, we have already taken a view. 1 know of no experiments which have satisfactorily de- termined in numbers, the relative conduct- ing power of liquids. Mercury for a liquid, possesses 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 po- pular experiments 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 beeswax, he plunged their other ends into a heated liquid. The heat travelled on- wards among the matter of each rod, and soon became manifest by the softening of the wax. The following 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, i Iron, \ much inferior to Steel, 1 the others. Lead, ) In my repetition of the experiment, I found silver by much the best conductor, next copper, 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 blow-pipe. It is owing to the inferior con- ducting 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 expands, while the adjacent parts retaining their pristine form and volume, do not accommodate them- selves 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 tempera- tures, 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. Morveati has rated the conducting power of charcoal to that of fine sand, as -<> to 3, a difference much too small. Spongy organic substances, silk, wool, cotton, &c. are still worse conduct- ors 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 gene- rated by the animal powers, is accumula- ted round the body by the imperfect con- ductors of which clothing is composed. To discover the exact law of the distri- bution of heat in solids, let us take a pris- matic 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 prismic bar, in the middle of a sheet of tin-plate, which is then to be fixed to the bar, to screen it and the thermometer, from the focus of heat. Immerse the ex- tremity 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 an- gles 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 experi- ments, projection and aerial currents mo- dify that result, making the thermometers rise more slowly, and preventing them from ever reaching the temperature of the end of the bar. Their state becomes in- deed stationary whenever the excess of temperature, each instant communicated by the preceding section of the bar, merely compensates what they lose by the contact of the succeeding section of the bar, and the other outlets of heat. The three ther- mometers now indicate three steady tem- peratures, but in diminishing progression. In forming an equation from the experi- mental results, M. Laplace has shown, that the difficulties of the calculation can be re- moved only by admitting, that a deter- minate 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 differ- entials 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 CAL CAL through the very substance of the solid ele- ments a true radiation, analogous to that observed in air, but whose sensible influ- ence is bounded to distances incomparably smaller. This result is in no respect impro- bable. 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 ra- diating caloric, prove that it does notman- ate solely from the external surface of bo- dies, but also from material particles situa- ted within this surface, becoming 1 no doubt insensible at a very slight depth, which probably varies in the same body, with its temperature. M. Biot, M. Fourier, and M. Poisson, three of the most eminent mathematicians and philosophers of the age, have distin- guished themselves in this abstruse inves- tigation. The following is the formula of M. Biot, when one end of the bar is main- tained at a constant temperature, and the other is so remote as to make the influ- ence of the source insensible. Let y repre- sent, in degrees of the thermometer, the temperature of the air by which the bar is surrounded; let the temperature of the fo- cus be y -f- Y; then the integral becomes, log.t/^log.Y-^-^/^ a 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 such case, agreeably to two ob- servations. M is the modulus of the or- dinary logarithmic tables, or the number 2.302585. M. Biot presents several tables of observations, in which sometimes 8, and sometimes 14 thermometers were applied all at once to successive points of the bar; and then he computes by the above formu- la, what ought to be the temperature 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 ther- mometers. 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 representation of the con- dition of the bar. With regard to the ap- plication 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 insufficiency. M. Biot himself after showing its exact co- incidence 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, tb give very valuable pyrometrical indications. The end of the bar which is to be exposed to the heat, being coated with fire-clay, or sheath- ed with platinum, should be inserted a few inches into the flame, and drops of oil be- ing put into three successive cavities of the bar, we should measure the tempera- tures of the oil, when they have become stationary and note the time elapsed, to pro- duce this effect. A pyroscope of this kind could not fail to give useful information to the practical chemist, as well as to the manufacturers of glass, pottery, steel, &c. 2. Of specific heat. If we take equal weights, or equal bulks, of a series of sub- stances; for example, a pound or a pint of water, oil, alcohol, mercury, and having heated each separately, in a thin vessel, to the same temperature, say to 80 or 1UO* Fahr. from an atmospherical temperature of 60, then in the subsequent cooling of these four bodies to their former state, they will communicate to surrounding me- dia very different quantities of heat. And conversely, the quantity of heat requisite to raise the temperature of equal masses of different bodies, an equal number of thermometric degrees, is different, but specific for each body. There is another point of view in which specific heats of bo- dies may be considered relative to their change of form, from gaseous to liquid, and from liquid to solid. Thus the steam of water, at 21<; , in becoming a liquid, does not change its thermometric tempe- rature 212, yet it communicates, by this change, a vast quantity of heat to sur- rounding bodies; and, in like manner, li- quid water at 32, in becoming the solid called ice, does not change its temperature as measured by a thermometer, yet it im- parts much heat to surrounding matter. We therefore divide the study of specific heats into two branches: 1. The specific heats of bodies while they retain 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 first mode, a given weight or bulk of the body to be examined, 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 re- lation between their specific heats. Hence, if the second body be water, or any other substance whose relation to water is ascer- CAL CAL tainecl, the relative heat of die 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 converse- ly, if we mix a pound of water heated to 90, with a pound of oil at 60, the tempe- rature of the mixture will be 80. We see here, that the water in the first case ac- quired 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 quantity or in- tensity of heat which will change the tem- perature of oil 20, will change that of wa- ter only 10; and therefore if the specific beat, or capacity for heat, of water be call- ed 1.000, that of oil will be 0.500. When the experiment has been, from particular circumstances, made with unequal weights, the obvious arithmetical reduction, for the difference, must be made. This is the ori- ginal method of Black, Irvine, and Craw- ford. The second mode is in some respects a modification of the first. The heated mass of the matter to be investigated, is so sur- rounded by a large quantity of the stand- ard 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 prac- tice of suspending a lump of heated inetal in the centre of a mass of cold water con- tained in a tin vessel: 2 Do. do. do. 4150 Do. do. do. 6000 He thinks these to be no nearer approxi- mations to the truth than Gadolin's. From the heat evolved in slaking"^ lime, compared to the specific heats j of the compound, and its constitu- )-4260 ents, lime and water, Mr. Dalton | gives as the zero, J From nitric acid and lime, Mr. Dalton finds - - - 11 000 From the combustion of hydrogen, 5400 From Lavoisier and Laplace's experi- ments on slaked lime, 3428 From their expei'iments on sulphuric asid and water, 7262 Do. do. do. 259S Do. from nitric acid and lime, -{- 23837 Dr. Irvine placed it below 30, 900 Dr. Crawford do. do. = 1500 The above result of Lavoisier and La- place 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. Clement 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 F. This is a more conceivable re- sult. But MM. Dulong and Petit have been led by their investigation to fix the abso- lute zero at infinity. " This opinion," say they, " rejected by a great many philoso- phers 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 spe- cific heats diminish as the temperatures sink. In fact the law of this diminution may be such, that the integral of heat, ta- ken to a temperature infinitely low, may notwithstanding have a finite value." They farther infer, that the quantity of heat de- veloped at the instant of the combination of bodies has no relation to the capacity of the elements; and that in the greatest num- ber of cases this loss of heat is not follow- ed 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 been drawn from it. 3. Of the general habittnles of heat t with the different forms of matter. The effects of heat are either transient and physical; or permanent and chemical, inducing a durable change in the constitu- tion of bodies. The second mode of opera- tion 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 vol- ume which bodies receive with successive increments 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 aug- mentation of volume which liquids :.nd gases suffer through a moderate thermo- metric range. \Ve 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 reci- pient, is a problem of no small difficulty. It seems, however, afler many vain at- CAL CAL tempts by precedi ng experimenters, to h ave been finally solved by MM. Dulong and Petit. The expansion of solids had been previously measured with considerable ac- curacy by several philosophers, particular- ly by Smeaton, Roy, Ramsden, and Trough- ton, in this country, and Lavoisier and La- place in France. The method devised by Genl. Roy, and executed by him in conjunc- tion with Ramsden, deserves the pjefer- ence. The metallic or other rod, the sub- ject of experiment, was pluced horizontally in a rectangular trough of water, which could be conveniently heated. At any ali- quot distance on the rod, two micrometer microscopes were attached at right angles, so that each being adjusted at first to two immoveable points, exterior to the heating apparatus, when the rod was elongated by heat, the displacement of the microscopes could be determined to a very minute quan- tity, 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 dis- tant. This addition of a micrometrical tel- escope was ingenious; but the whole me- chanism 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 regard 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 origi- nality and philosophical precision. They commenced with mercury. Their method with it is founded on this incontestable law of hydrostatics, that when two columns of a liqurd communicate by means of a lateral tube, the vertical heights of these two co- lumns are precisely the inverse of their densities. In the axis of two upright cop- per cylinders, vertical tubes of glass were fixed, joined together at bottom by an hori- zontal 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 rect- angular inverted glass syphon was filled nearly to the top with mercury, and the height at which the liquid sto'od in each leg was determined with nicety by a teles- copic micrometer, revolving in a horizon- tal plane on a vertical rod. The telescope had a spirit level attached to it, and could be moved up or down a very minute quan- tity by a fine screw. The temperature of the oil, the medium of heat, was measured by both an air and a mercurial thermome- ter, whose bulbs occupied nearly the whole vertical extent of the cylinder. The elon- gation of the heated column 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 ascer- tained the expansions of mercury throug'h different thermometric ranges, they then determined the expansion of glass from the apparent 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 boil- ing water. On withdrawing, wiping, and weighing it, they learned the quantity of mercury expelled, which being compared with the whole weight of the mercury in it at the temperature of melting ice, gave the dilatation of volume. This is precisely the plan employed long ago by Mr. Crightou, as well as myself, and which gave the quan- tity 1-63(1, employed in my paper for the apparent dilatation of mercury in glass. Their next project was to measure the dilatation of other solids; and this they ac- complished with much ingenuity by en- closing a cylinder of the solid, iron for ex- ample, in a glass tube, which was filled up with mercury, after its point had been drawn out to a capillary point. The mercu- ry having been previously boiled in it, to expel all air and moisture, the tube was exposed to different temperatures. By de- termining the weight of the mercury which was driven out, it was easy to deduce the dilatation of the iron; for the volume driven out obviously represents the sum of the di- latations of the mercury and the metal, di- minished by the dilatation of the glass. To make the calculation, it is necessary to know the volumes of these three bodies at the temperature of freezing water; but that of the iron is obtained by dividing its weight by its density at 3i. We deduce in the same manner 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 ap- plied likewise to other metals, taking the precaution merely to oxidize their surface to hinder amalgamation. In the years 1812 and 1813 I made many experiments with a micrometrical appara- tus of a peculiar construction, for measur- ing the dilatation of solids. I was particu- larly 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 expansive force of heat, present such an adhesive friction as to pre- CAL CAL vent their entire retraction. It would be de- sirable to know the limit of this effect, and to see what other metals are subject to the same change. 1 hope to be able ere long to finish these pyrometrical researches. I shall now present a copious table of di- latations, newly compiled from the best ex- periments. TABLE I. Linear Dilatation of Solids by Heat. Dimensions which a bar takes at 212, whose length at 32 i 5 1.000000. Dilatation in Vulgar Fractions. Glass tube, Smeaton, 1.00083333 do. Roy, 1.00077615 do. Deluc's mean, 1.00082800 do. Dulong and Petit, 1.00086130 TTT3" do. Lavoisier and Laplace, 1.00081166 TlW Plate glass, do. do. 1.000890890 TTW do. crown glass, do. do. 1.00087572 TTT do. do. do. do. 1.00089760 TTTT do. do. do. do. 1.00091751 ToTO do. rod, Roy, 1.00080787 Deal, Roy, as glass, Platina, Borda, 1.00085655 do. Dulong and Petit, 1.00088420 TT^T do. Troughton, 1.00099180 do. and glass, Berthoud, 1.00110000 Palladium, \Vollaston, 1.00100000 Antimony, Smeaton, 1.00108300 Cast iron prism, Roy, 1.00110940 Cast iron, Lavoisier, by Dr. Young, 1.00111111 Steel, Troughton, 1.00118990 Steel rod, Roy, 1.00114470 Blistered steel, Phil. Trans. 1795. 428, 1.00112500 do. Smeaton, 1.00115000 Steel not tempered, Lavoisier and Laplace, 1.00107875 sir do. do. do. do. do. 1.00107956 i do. tempered yellow, do. do. 1.00136900 do. do. do. do. do. 1.00138600 do. do. do. at a higher heat , do. do. 1.00123956 o'7 Steel, Troughton, 1.00118980 Hard steel, Smeaton, 1.00122500 Annealed steel, Muschenbroek, 1.00122000 Tempered steel, do. 1.00137000 Iron, Borda, 1.00115600 do. Smeaton, 1.00125800 Soft iron forged, Lavoisier and Laplace, 1.0012204: Round iron, wire-drawn, do. do. 100123504 Iron wire, Troughton, 1.00144010 Iron, Dulong and Petit, 1.00118203 ffis" Bismuth, Smeaton, 1.00139200 Annealed gold, Muschenbroek, 1.00146000 Gold, Ellicot, by comparison, 1.00150000 f do. procured by parting, Lavoisier and Laplace, 1.00146606 *1 do. Paris standard, unannealed. do. do. 1.00155155 2 0.0600 2TV? T y 0.1100 0.0600 iV 0.1100 i 0.0460 0.0500 A 2^ 0.0700 0.0800 rlT CAL CAL Oil of turpentine, do. 0.0700 The quantities given by Mr. Dalton, are probably too great, as is certainly the case with mercury; his experiments being perhaps modified by his hypothetical notions, Water saturated with common salt, Robinson, 0.05198 Dr. Young, in his invaluable Catalogue raisonnte. Natural Philosophy, vol. ii. p. 39 i. gives the following table of the ^cpan- sions of water, constructed from a colla- tion of experiments by Gilpin, Kirwan, and A chard. He says, that the degrees of Fahrenheit's thermometer, reckoning either way from 39 being called /, the expansion of water is nearly expressed by 22/ 2 (1 .002/) in 10 million ths; and the diminution of the specific gravity by .0000022/ 2 00000000472/ 3 . This equa- tion, as well as the table, are very import- ant for the reduction of specific gravities of bodies, taken by weighing them in water. Sp. grav. 30 0.99980 32 0.99988 34 0.99994 39 1.00000 44 0.99994 48 0.99982 49 0.99978 54 0.99951 59 0.99914 Dimin. Expan- ofsp.gr. sion< 0.00020 0.00012 0.00006 0.00000 0.00006 0.00018 0.00022 0.00049 0.00086 Sp. grav. 60 0.99>06 64 0.99867 69 0.99812 74 0.99749 (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 100 0.99313 102 0.99246 Kirwan 122 0.98757 0.98872 Deluc 142 0.98199 K. 162 0.97583 167 0.97480 Deluc 182 0.96900 K. 202 096145 212 0.95848 . Deluc introduced into a series of ther- mometer glasses, the following liquids, and noted their comparative indications by ex- pansion at different degrees of heat, mea- suring on Reaumur's thermometer, of which 80 is the boiling point of water, and the melting point of ice. Dimin. Expan- of sp. gr. sion. 0.00094 0.00133 0.00188 0.00251 0.00489 0.00491 0.00687 0.00692 0.00754 0.00760 0.01243 0.01258 0.01128 0.01801 0.01833 0.02417 0.02481 0.02520 003100 0.03198 0.03855 0.04005 0.04152 0.04333 TABLE of Thermometric Indications by DELUC. J\fercnrv. Olive Oi. Es. Oil of Chamnmile. Oil of Thyme. Alcohol. Brine. Water. R. Cent. Fahr. 80 100 sis 80 80 80 80 80 80 75 93$ 200$ 74.6 74.7 74.3 73.8 74.1 71 70 87.5 189$ 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. 167 593 59.1 58.3 56.2 57.1 45.8 55 68$ 155$ 54.2 53.9 53.3 50.7 51.7 38.5 50 62$ 144$ 49.2 48.8 48.3 45.3 46.6 32. 45 56* 133-i 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$ 1 10$ 34.2 33.6 33.5 3Q.3 31.3 15.9 30 37$ 99$ 29.3 28.7 28.6 25-6 265 11.2 25 3U 88-j 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 18$ 65$ 14.4 14.1 14.2 12.2 12.8 1.6 10 12$ 54$ 9.5 9.3 9.4 7.9 8.4 0.2 5 43* 4.7 4.6 4.7 3.9 4.2 0.4 32 0.0 0.0 0.0 0.0 0.0 0.0 5 6i 20$ 3.9 4.1 10 12$ 9$ 7.7 8.1 As I consider these results of Deluc va- added the two columns marked Cent, and luable, in so far as they enable us to com- Fahr. to give at once the reductions to pare directly the expansions in glass of the centigrade and Fahrenheit graduation, these different thermometric liquids, I have The alcohol was of such strength that its CAL CAL flame kindled gunpowder, 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 elabo- rate Trait de Physique, has investigated several empyrical formulae, 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 -f. bt 2 -f- cts, in which t denotes the temperature in degrees of the mercurial thermometer; a b c constant coefficients, which depend on the nature of the liquid, and t the true dilata- tion for the volume 1.0 from the tempera- ture of melting ice. We shall content our- selves with giving one example, from which we may judge of the great geometrical re- sources of this philosopher. For olive oil the formula becomes 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 Of the mercurial. 60 50 40 30 20 10 Observed. 59.3 49.2 39.2 29.3 19.3 9.5 0. Calculated. 59.37 49.2 39.12 29.15 19.30 9.53 0.0 M. Gay-Lussac has lately endeavoured to discover some law which should corres- pond with the rate of dilatation of different liquids by heat. For this purpose, instead of comparing the dilatations of different liquids, above or below a temperature uni- form for all, he set out from a point variable with regard to temperature, but uniform as to the cohesion of the particles of the bo- dies; namely, from the point at which each liquid boils under a given pressure. Among those which he examined, 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 115.9 Fahr. The other liquids did not present, in this respect, the same resem- blance. 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 distinguished chemist. TABLE of the Contractions of 1000 parts in volume* by cooling. Water. Jllcohol. Sulphuret of Curb. Ether. Contract Ditto Contract by ex [ft. calculated, by exp t Ditto ( alculated. C'jntruci by exp't Ititto calculated. Contract Ditto by exp't. calculated. Boiling. 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 3.34 3.35 5.55 556 6.14 6.07 8.15 > .16 10 6.61 6.6.) li 4: : 11.24 12.01 12.08 16 17 16.01 15 10.50 989 17.51 17.00 1 .98 17.99 ^24.16 23.60 20 13.15 13.03 24.34 23.41 2380 23.80 31 83 30.92 25 16.06 16.06 29 15 28.60 29.65 2950 ,-9.14 3.-J.08 30 18.85 18.95 3474 34.37 35.06 35.05 46.42 45.04 35 21.52 21.67 40.28 40.05 40.48 40.43 2*06 51.86 40 24.10 24.20 45.68 4566 45.77 45.67 5877 58-77 45 26.50 26.52 5085 51 11 51.08 50.70 65 .8 6520 50 28.56 .861 56.0 5637 50.28 55.52 72^1 / 1 79 55 30.60 30.43 61.01 61.43 61.14 60 12 78..5fc 78.56 60 32.42 31.96 6596 06.23 6621 64.48 65 34.02 33.19 1074 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 VOL. I. The experiments were made in thermo- meter vessels, hermetically sealed. Alcohol, at 78.41 cent, produces 483.3 its vol. of vapour. 31 CAL CAL 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. Dr. Thomson, treating of expansion, states, that " different kinds of glass differ so much from each other, that no general rule can be laid down." System, ^ - ol. i. page 73. This statement is at variance with the results of MM. Dulong and Petit, as well as of my own pyrometrical mea- surements. " Nor have we found," say these accurate observers, " any apprecia- ble difference between the effects observed in tubes of ordinary glass obtained from different manufactories, whatever was their calibre or their thickness." T believe the differences to have arisen from the errors of the previous pyrometrical measure- ments, applied to a body whose dilatation is so small. Thus General Roy, perhaps the most accurate of all experimenters, found at one time, that a glass tube ex- panded four times as much as a rod; and he afterwards found; on the contrary, that the rod expanded more than the tube by about -%j, the glass being from the same pot. I found, that a rod and tube made out of the same glass pot expanded the same quantity, through a range of 400 Fahr.; and believe, that such crystal or flint-glass as is used in Great Britain for chemical purposes, is wonderfully uniform in its rate of dilatation by heat, through the same portions of the thermometric scale. Nor are the differences considera- ble between the expansions of crown and plate glass. The different rate of expansion which liquids undergo, by the same degree of temperature, has been theorized upon by Dr. Thomson; and as this is the only ex- ample in his writings in which he has ven- tured to propound an original philosophi- cal law, it is entitled to examination. 'Alcohol, 0.1100= i Nitric acid, (sp. gr. 1.40) - 0.1100 = Fixed oils, - 0.080 = ^ Sulphuric ether, 0.070 = tV Oil of turpentine, - - 0.070 % Muriatic acid, (sp. gr. 1.137.) 0.060 = -^ Sulphuric acid, (sp. gr. 1.85.) 060 = -? Water saturated with common salt, 0.05 = ^V Water, . 0.0466 = ^ Mercury, . . 0.02 = V " The expansion of liquid bodies differs from that of the elastic fluids, not only in quantity, but in the want of uniformity with which they expand, when equal ad- ditions are made to the temperature of each. This difference seems to depend upon the fixity or volatility of the compo- nent parts of the liquid bodies; for in gene- ral those liquids expand most by a given addition of heat whose boiling tempera- tures are lowest, or which contain in them an ingredient which readily assumes the gaseous form. Thus mercury expands much less when heated to a given tempera- ture than water, which boils at a heat much inferior to mercury; and alcohol is much more expanded than water, because its boiling temperature is lower. In like man- ner, nitric acid is much more expanded than sulphuric acid, not only because its boiling point is lower, but because a por- tion of it. has a tendency to assume the form of an elastic fluid. This rule holds at least in all the liquids Avhose expansions I have hitherto tried. We may consider it therefore as a pretty general fact, that the higher the temperature necessary to cause a liquid to boil, the smaller the expansion is which is produced by the addition of a degree of heat; or, in other words, the ex- pansibility of liquids is nearly inversely as their boiling temperatures." Thomson's Chemistry, 5th edition, vol. i. pp. 66 and 67. After enforcing, in such varied expres- sions, his new law, that the lower the boil- ing point of a liquid is, the greater is its expansibility by heat, one would not ex- pect to find it completely abrogated and set at nought, by a table of experimental results in the very same page, let such is the fact, as its quotation will prove. " The following table exhibits the dila- tation of various liquids, from the tempera- boiling point, 174 ditto ditto ditto ditto ditto ditto ditto ditto ditto 247 600 98 314 217 620 225 212 636" I have added the boiling points as set down in his System. We here remark that alcohol and nitric acid have the same rate of expansion affixed, though the distances of their respective boiling points from 32 are as 2 to 3. But the most amusing illus- tration of the converse of Dr. Thomson's law, is presented by himself with regard to fixed oil and ether, the former having the greater expansion, though its boiling CAL GAL point is about -ten times more distant in thermometric "degrees, than that of ether, from 32. Ether and oil of turpentine ex- pand the same proportion, and yet their boiling points differ by 216. But'muriatic acid and sulphuric acid also expand the same quantity, though their boiling points, and " their tendencies to assume the form of an elastic fluid" are exceedingly differ- ent. Finally, water expands less than sul- phuric acid, while its boiling temperature is greatly loiver. Had Dr. Thomson pro- pounded the very reverse proposition, viz. that the rate of expansion in iiquids is higher the higher their boiling temperatures, he would have encountered fewer contra- dictory facts, though still enow to explode the generality of the principle. In a philo- sophical system of chemistry, examples of such false reasoning are injurious to the student, and lower the rank of the science. Mercury in its expansions, follows the rate of fluid metals, and therefore is riot properly comparable to oily, watery, or spirituous liquids. It is cui-ious that one of the examples which Dr. Thomson adduces to illustrate his pretended rule, which " holds, he says, at least in all the liquids whose expansion I have hitherto tried," actually breaks it; for alcohol expands fully a half more than ether; and yet, the inter- val from its boiling point to 32, is more than double that interval in ether, instead of being greatly less as his law requires. Since his table obviously disqualifies wa- ter, alcohol, ether, oils, and acids, from constituting such a series in expansion, as his rule requires, one may naturally ask this celebrated chemist, what are " the li- quids whose expansion he has hitherto tried? In solid metals, the expansion seems to be greater, the less their tenacity and den- sity, though to this general position, we have strikingexceptions in antimony and bis- muth, provided they were accurately mea- sured by Smeaton's apparatus, of which, however, I have reason to doubt. The least flexure in the expanding rods, will evi- dently 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. Duiong and Petit. Temperatures by Expansions in dilatation of air. bulk of Iron. Cop. Plat. to 100, cent, give ^ T J T -fa to 300, mean quantity, ^-J T T | y ^.J^ Tripling these denominators, we have the linear expansions, fractionally express- ed, thus: Iron. Cop. Plat. to 100 cent. to 300, mean, To multiply inductive generalizations, that is, to groupe 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 phenomena into a shape suit- ed to a preconceived constitution of things, was the vice of the Peripatetic schools, which Bacon so admirably exposed; of which in our times and studies, according to MM. Duiong and Petit, Mr. Dalton's 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 uniform by the same increase of tempera- ture; a fact of great importance to practi* cal chemistry, which was fully verified by the independent and equally original re- searches of M. Gay-Lussac on the sub- ject, with a more refined and exact appa- ratus. The latter philosopher demonstra- ted, that 100 in volume at :>2 Fahr. or cent, become 1.375 at 2lJ Fahr. or 100 cent. Hence the increment of bulk for each degree F. is -~|- = 0.002083 T^ff? and for the centigrade scale it is '^ * = =0.00375 Beers'. To reduce any vo- lume of gas, therefore, to the bulk it would occupy at any standard temperature, we must multiply the thermometric difference in degrees of Fahr. by 0.002083, or -^ subtracting the product from the given vo- lume, if the gas be heated above, but adding it, if the gas be cooled below, the standard temperature. Thus 25 cubic inches at 120 Fahrenheit will at 60 occupy a volume of 21 J; for -|^ X 60 = _60_ __ . and as == ^g-, which, taken from 25, leaves 21-jjp A table of reduction will be found under GAS. When the table is expressed deci- mally, indeed, to 6 or 7 figures, it becomes more troublesome to apply than the above rule. Vapours, when heated out of con- tact of their respective liquids, obey the same law us gases, a discovery due to M. Gay-Lussac. We shall now treat of the anomaly pre- sented by water in its dilatations by change of temperature, and then conclude this part of tiie subject with some practical ap- plications 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 cer- tain point, after which the further pro- gress of refrigeration was accompanied by GAL CAL an ascent of the liquid, indicating 1 expan- increase or decrease. Having omitted to sion of the water. This curious phenome- make the requisite correction for the ef- non was first accurately studied by M. De feet of the expansion of the glass in which Luc, who placed the apparent term of the water was contained, it was found af- greatest density at 40 Fahr., and consi- tei wards by Sir Charles Blitgden and Mr. dered the expansion of water from that Gilpin, who introduced this correction, point, to vary with equal amount, by an that the real term of greatest density was equal change of temperature, whether of 39 F. The folio-wing' Table jpves their Experimental results. Specific Gravity. Bulk of Water. temperature. Bvlk * water. Specific Gravity. I 00000 39 1.00000 1.UOOOO .00000 38 40 1.00000 1.00000 999',9 i.ooooi 37 41 1.00001 0.99999 0.9 ( -998 .OOOOJ 36 42 1.00002 0.99998 0.99996 .00004 35 43 1.00004 0.99996 0.9999 h 1.00006 34 44 1 00006 0.99994 0.99991 .000-8 33 45 i 1.00009 0.99991 0.999H8 1.00012 3 J 46 1 00012 099988 By weighing 1 a cylinder of copper and of glass in water at diiferent temperatures, the maximum density comes out 40 F. Final- ly Dr. Hope, in 1804, published a set of ex- periments in the Edin. I'hil. Trans, in which the complication introduced into the ques- tion by the expansion of solids, is very phi- losophically removed. He shows that water exposed in tall cylindrical vessels, to a freezing atmosphere, precipitates to the bottom its colder particles, till the tempe- rature of the mass sinks to 39.5 F. after which the colder particles are found at the surface. He varied the form of the experi- ment by applying- a zone of ice, round the top, middle, and bottom of the cylinders; and in each case, delicate thermometers 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, adop- ted by the French, in settling their stand- ard 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 des arts et metiers at Paris, that the two side walls of a gallery were receding from each other, being pressed outwards by the weight of the roof and floors. Several holes were made in each of the walls, opposite to one another, and at equal distances, 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. AH 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 screw- ed 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 ex- tremities, and permitted their end plates to be further screwed on. The first series of bars being again heated, the above pro- cess was repeated in each of its steps. By a succession of these experiments they re- stored the walls to the perpendicular posi- tion; and could easily have reversed their curvature inwards, if they had chosen. The gallery still exists with its bars, to at- test the ingenuity of its preserver M. Mo- lard. 2d, Of the change of state produced in bodies by caloric, independent of change of composition. The three forms of matter, the solid, liquid, and gaseous, seem immediate- ly referable to the power of heat, modify- ing, balancing, or subduing cohesive attrac- tion. In the article blow-pipe, we have shown that every solid maybe liquefied, and many of them, as well as all liquids, may be va- porized at a certain elevation of tempera- ture. 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 other elas- tic fluids into liquids or solids, it is proba- bly owing to the limited power we possess over thermometric depression. But we know, that by mechanical approximation of their elastic particles, an immense evo- lution of heat is occasioned, which must convince us that their gaseity is intimately dependent on the operation of that repul- sive power. CAL Sulphuric ether, always a liquid in our climate, if exposed to the rigors of a Sibe- rian 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 unna- tural condition. But by generalizing 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 tempe- rature. If we pass the easily condensed vapour of nitric acid through a red-hot glass tube, we shall convert it into gases which are incondensable by any degree of cold which we can command. The particles which formed the liquid can no longer join together to reproduce it, because their dis- tances are changed, and with these have also changed the reciprocal attractions which united them. Were our planet removed much further from the SUB, liquids and gases would so- lidify; were it brought nearer that lumi- nary, the bodies which appear to us the roost solid, would be reduced into thin in- visible air. We see, then, that the princi- ple of heat, whatever it may be, whether matter or quality, separates the particles of bodies when its energy augments, and suffers them to approach when its power is enfeebled. By extending this view, it has been drawn into a general conclusion, that this principle was itself the force which maintains the particles of bodies in equi- libria against the effort of their reciprocal attraction, which tends continually to bring them together. But although this conclu- sion be extremely probable, we must re- member 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 princi- ple of heat, but this does not necessarily prove that these forces are of the same na- ture. The instant of equilibrium which sepa- rates the solid from the liquid state, de- serves consideration. 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 quali- ties are equal, a particle which mav br cy- lindrical, for example, will not exercise the same attraction as a sphere, on a point pla- ced at an equal distance from its centre of gravity. Thus in the law of celestial gravi- tation, the attraction of an ellipsoid on an exterior point, will be stronger in the di- rection of its smaller than in that of its larger axis, at the same distance from its surface. Now whatever be the law of at- tractions which holds together the parti- cles of bodies, similar differences must ex- ist. These particles must be attracted more strongly by certain sides than by others. Thence must result differences in the man- ner of their arrangement, when they are sufficiently approximated for their attrac- tions to overcome the repulsive power. This explains to us in a very probable man- ner, the regular crystallization which most solid bodies assume,when they concrete un- disturbed. 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 mag- nificent effects of this attraction dependent on figure. Such are the phenomena of nu- tation 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 rota- tion, in a manner which may be mathemati- cally deduced, and subjected to calculation. But the investigation shows, that this part of the attraction dependent on figure, de- creases 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 dis- tance. Thus also, in the attractions which hold the parts of bodies united, we ought to expect an analogous difference to occur. 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 indif- ferent to all the positions which they can assume round their centre of gravity; this will constitute the liquid condition. Sup- pose now that the temperature falling, the particles approach slowly to each other, and tend to solidify anew; then the forces de- pendent on their figure will come again in- to play, and in proportion as they increase, 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 crystal- lization demands. Now according to the figure of the particles, we may conceive that these movements may react on their centre of gravity, and cause them to ap- proach 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 oc- cupied as liquids. These mechanical con- siderations thus explain, in the most prob- able and satisfactory manner, the dilatations and contractions of an irregular kind, which certain liquids, such as water and mercu- CAL CAL py, experience, on approaching the term of their congelation. Having- given these gen- eral views, we may now content ourselves with stating the facts as much as possible in a tabular form. TABLE of the Concreting or Congealing Temperatures of various Liquids, by FAH- RENHEIT'S Scale. 46 46 1.424 45.5 1.6415 45 39 Sulphuric ether, Liquid ammonia, - Nitric acid, sp. >r. Sulphuric acid, sp. gr. Mercury, Nitric acid, sp. gr. 1.407 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 -f 1. Pure prussic acid, - 4 to 5 Common salt, 25 -f water 75 4 Do 22.2 -f do. 77.8 7.2 Sal ammoniac, 20 -j- do. 80 8 C. salt, 20 -f- 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 -f do. 90 21.5 Oil of bergamot, - 23 Blood, - 25 C. salt, 6.25 -f water 93.75 25.5 Eps salts, 41.6 + do. 58.4 25.5 Nitre, 12.5 -f do. 87.5 26. C. salt, 4.16 + do. 95.84 27.5 Copperas, 41.6 + do. 58 4 Vinegar, - 28 Sul. of zinc, 53.3 -f- water 46.7 28.6 Milk, - - 30 Water, Olive oil, - 36 Sulphur and phosphorus, eq. 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, 92 Phosphorus, 108 Stearin from hog's lard, - - 109 Spermaceti, - - - - 112 Tallow, Nicholson, - 127 Margaric acid, - - 134 Potassium, .... 136.4 Yellow wax, - 142 Do. Do. 149 White wax, - - - - 155 Sodium, 194 Sulphur, Dr. Thomson, - - 218 Do. Dr. Hope, - - - 234 Tin, 442 Bismuth, 476 Lead, 612 Zinc, by Sir H .Davy, - - 680 Zink, Brongniart, - - - 698 Antimony, .... 809? See PYROMETER for higher heats. The solidifying temperature of the bo- dies above tallow, in the table, is usually called their freezing or congealing point; and of tallow and the bodies below it, the fusing or melting point. Now, though these temperatures be stated, opposite to some of the articles, to fractions of a thermo- metric degree, it must be observed, that various circumstances modify the concret- ing 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 of- fered on the forces concerned in the tran- sition from liquidity to solidity, will in some measure explain these variations; and we shall now illustrate them by some instruc- tive examples. If we fill a narrow-mouthed matrass with newly distilled water, and expose it very gradually to a temperature considerably below 32, the liquid water will be observ- ed, by the thermometer left in it, to have sunk 10 or 11 degrees below its usual point of congelation. M. Gay-Lussac, by cover- ing the surface of the water with oil, has caused it to cool '21^ degrees Fahr. below the ordinary freezing temperature. Its vo- lume at the same time expanded as much as if it had been heated 21^ degrees above 32. According to Sir Charles Blagden, to whom the first of these two observations belongs, its dilatation may amount to l-7th of the total enlargement, which it receives by solidifying. Absolute repose of the li- quid particles is not necessary to ensure the above phenomenon, for Sir Charles stir- red water at 21 without causing it to freeze, but the least vibration of their mass, or the application of icy spiculx, by the atmosphere, or the hand, determines an instantaneous congelation. 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 instantaneously by the ready formed aqueous solid, the particles of which presenting themselves to those of the liquid, by their sides of greatest attrac- tion, will compel them to turn into similai' 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 pro- pagated through the whole mass, till all be congealed. The vibratory movements act by CAL CAL throwing- the pavticles, into positions favor- able for their mutual attraction. The very same phenomena occur with saline solutions. If a hot saturated solution of Glauber's salt be cooled to 5;j under a film of oil, it will remain liquid, and will bear to be moved about in the hand with- out any change; but if the phial containing it be placed on a vibrating- table, crystal- lization 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 mechani- cal disturbance in determining crystalliza- tion, is illustrated bv the symmetrical dis- position of particles of dust and iron, by electricity and magnetism. Strew these up- on 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 parti- cles, 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 so- lidity, not only removes the particles to dis- tances beyond the sphere of mutual attrac- tion, but probably also inverts their attract- ing poles." Perhaps the term avert would be more appropriate to liquidity, to denote an obliquity of direction in the attracting poles; and revert might be applied to gasei- ty, when a repulsive state succeeds to the feebly attractive powers of liquid particles. The above table presents some interest- ing particulars relative to the acids. I have expressed their strengths, by specific gra- vity, from my tables of the acids, instead of by the quantity of marble which 1000 grains of them could dissolve, in the original state- ment of Mr. Cavendish. Under the heads of nitric acid and equivalent, some observa- tions will be found on these peculiarities with regard to congelation. We see that common salt possesses the greatest effica- cy in counteracting the congelation of wa- ter; and next to it, sal ammoniac. Mr. Crigh- ton of Glasgow, whose accuracy of obser- vation is well known, has remarked, that when a mass of melted bismuth cools in the air, its temperature falls regularly to 463, from which term it however instantly springs up to 476, at which point it re- mains till the whole be consolidated. Tin in like manner sinks and then rises 4 de- grees; while melted lead, in cooling, be- comes stationary whenever it descends to 612. We shall presently find the probable cause of these curious phenomena. Water, all crystallizable solutions, and the three metals, cast-iron, bismuth, and antimony, expand considerably 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 wa- ter in their cavities, when it is converted into ice. In the same way our pavements are raised in winter. The beneficial opera- tion of this cause is exemplified in the com- minution or loosening the texture of dense clay soils, by the winter's frost, whereby the delicate fibres of plants can easily penetrate them. Major Williams of Quebec, burst bombs, which were filled with water and plugged up, by exposing them to a freezing cold. There is an important circumstance oc- curs 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 temperature 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 degrees hot- ter than the surrounding medium. We owe the explanation of this fact, and its exten- sion to many analogous chemical phenome- na, 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 atmos- phere. A lump of ice at 2^ freely suspend- ed in a room heated to 50, which will rise to 3. c fc in 5 minutes, will take 14 times 5, or 70 minutes, to melt into water, whose temperature will be only 32. Dr. Black sus- pended in an apartment two glass globes 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 result- ing 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 mi- nutes, 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 fragments with a pound of water at 172. Its liquefaction is CAL CAL instantly accomplished, but the tempera- ture of the mixture is only . : . < 2. Therefore 140 of heat seem to have disappeared. Had we mixed a pound of ire-cold water with a pound of water at 17'^, the result- ing" temperature would have been Iu2, proving- that the 70 which had left the hot- ter portion, were manifestly transferred to that which was cooler The converse of the preceding- experiments may also be *le- monstrated; for in suspending- a flask of water, at 55 for example, in an atmosphere at 20, if it cool to 3^ in S minutes, it will take ly 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 expended solely in giving elastic tension, or, according to Irvine, in supplying the vastly increased capacity of of the aeriform state; and therefore they may be. denominated latent heat, being in- sensible to the thermometer. The more ex- act 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 ex- periments made in a different way, as will be presently shown. Every attentive opera- tor must have observed the greater explo- sive violence and apparent difficulty of the ebullition of water exposed to a similar heat in glass, than in metallic 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 par- ticles of pounded glass thrown into the former vessel, reduces 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 ebullition will recom- mence on throwing in a pinch of iron filings. Professors Munche and Gmelin of Hei- delberg have extended these researches, and given the curious results as to the boil- ing points, expressed in the following table: Substance of the Silver, Platina, Copper, Tinned iron, Marble, Lead, Tin, Porcelain, White glass, Green glass, Th Do. inch beloiv sitr- water. 211-775 211. 55 211.775 210.875 212.900 212225 213.24 211.66 212. 10 211. 66 212. 45 211.775 212. 7 211.775 212. 1 211.900 212. 7 212. 00 213. 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 varia- tions 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 acquire a greater degree of heat than that of the real boiling point, pro- vided the fluid be enclosed in a vessel, and heated at the bottom. In this case, the ad- hesion of the fluid to the vessel may be considered as analogous in its action to vis- cidity, in raising the temperature of ebul- lition. On this principle we explain the sud- den starts which sometimes take place in the boiling of fluids. This frequently oc- curs to a great degree in distilling sulphu- ric acid, by which the vessels are not un- frequently 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 disen- gagement of gas will be prevented and con- sequently the vessels not be liable to be bro- ken." innalesde Chimie, March 1818. See my remarks on this subject under the DIS- TILLATION of SULPHURIC ACID, extract- ed from the Journal of Science, October 1817. If we throw a piece of paper, a crust of bread, or a powder, into a liquid slight- ly impregnated with carbonic acid, its evo- lution will be determined. See some cu- rious 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 ofl' gas or vapour pre- sent in the liquid which it contains. In all the examples of the preceding ta- ble, the temperature is greater at the bot- tom than near the surface of the liquid; and the specific differences must be ascribed to the attractive force of the vessel to wa- ter, 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 ele- vated temperatures, which do not appa- rently exist with regard to silver and pla- tina. 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: Soiling point a. Ether, sp. gr. 0. 7365 at 48. G. Lussac, 100 Carburet of sulphur, - do. Alcohol, sp. gr. 0.813 Ure, 173.5 Nitric acid, 1.500 Dalton, 210 Water, 212 Saturated sol. of Glaub. salt. Biot, 213? CAL GAL Boiling 1 points. Saturated sol. of sugar of lead, Biot, 2l5f Do. do. sea salt, do. 224-J- Muriate of lime 2 -f water 1 Ure, 230 Do. 35.5 -f- do. 64.5 do. 235 Do. 40.5 -f- do. 59.5 do. 240 Muriatic acid, 1.094 Dalton, 232 Do. 1.127 do. 222 Do. 1.047 do. 222 Nitric acid, 1.45 do. 240 Do. 1.42 do. 248 Do. 1.40 do. 247 Do. 1.35 do. 242 Do. 1.30 do. 236 Do. 1.16 do. 220 Rectified petroleum, - Ure, 306 Oil of turpentine, - do. 316 Sulp. acid sp. gr. 1.30 + 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 Sulphur, - 570 Linseed oil, .... 640? Mercury, (Dulong, 662), 656 These liquids emit vapours, which, at their respective boiling 1 points, balance a pressure of the atmosphere, equivalent to thirty vertical inches of mercury. But at inferior temperatures they yield vapours of inferior elastic power. It is thus that the vapour of quicksilver rises into the va- cuum of the barometer tube; as is seen par- ticularly in warm climates, by the mercu- rial dew on the glass at its summit. Hence aqueous moistures adhering to the mercu- ry, causes it to fall below the true barome- ter level, by a quantity proportional to the temperature. The determination of the elas- tic force of vapours, in contact with their respective liquids, at different tempera- tures, has been the subject of many ex- periments. The method of measuring their elasticities, described in my paper on HEAT, seems convenient, and susceptible of precision. A glass tube about one-third of an inch internal diameter, and 6 feet long, is seal- ed at one end, and bent with a round cur- vature in. the middle, 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 be- tween the legs, and fixed firmly by twine, about 6 inches from the ends of the sy- phon. Dry mercury is now introduced, so as to fill the sealed leg, and the bottom of the curvature. On suspending- this syphon barometer in a vertical direction, by the cork, the level of the mercury will take a position in each of the legs, corresponding to the pressure of the atmosphere. The dif- ference is of course the true height of the barometer at the time, which may be mea- sured by the application of a separate scale of inches and tenths. Fix rings of fine pla- tinum wire round the tube at the two levels of the mercury. Introduce now into the tube a few drops of distilled water, recent- ly boiled, and pass them up through the mercury. The vapour rising from the wa- ter 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 accu- racy, would be difficult; but the total de- pression, 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 pla- tina ring, which is shewn by a delicate film of light, as in the mountain barome- ter. 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 mercurial level, to its summit. This is easi- ly accomplished, 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 bot- tle, 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 vertical position from a high frame, or the roof of an apartment, we introduce wa- ter 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 sur- rounding medium, mercury is slowly add- ed 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 CAL CAL 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 the opposite shoulders of the cylinder. By adjusting the flames, and agitating the li- quid, very uniform temperatures may be given to the tube in the axis. At every 5 or 10 of elevation, we make a measurement by pouring mercury into the open leg, till the primitive level is restored in the other. For temperatures above 2lJ, I employ the same plan of apparatus, slightly modi- fied. 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 me- dium of oil. If the bending of the tube, be made to an angle of about 35 from paral- lelism of the legs, a tubulated globular re- ceiver becomes a convenient vessel for holding the oil. The tapering cork through which the sealed end of the syphon is pas- sed, being thrust into the tapering mouth of the receiver, remains perfectly tight at all higher temperatures, being progres- sively swelled with the heat. One who has not made such trials, may be disposed to cavil at the probable tightness of such a contrivance, but 1 who have used it in ex- periments for many months together, fcnow 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 thermometer. The Tables of Vapour, in the Appendix, exhibit the results of some care- fully conducted experiments. 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 212 30 being divided by 1.23, will give the force for 10 below; this quotient divided by 1.24, will give that 10 lower, and so on progressive- ly. To obtain the forces above 212, we have 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 re- sults. " Let r r= the mean ratio between that of 210 and the given temperature; 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 ^r n Log. r,- the positive sign being used above, the negative below 210." I have investigated also simple ra- tios, which express the connexion between the temperature and elasticity of the va- pours of 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 Fah- renheit -j- 85 = D, and the corresponding force of steam in inches of mercury 0.09 == I. Then Log. D 2.22679X6 = Log. I. EXAMPLE. 212 -f 85= 297Log. = 2.47276 2.22679 constant number. 0.24579 X 6 Log. 1.47582= 29.91 ~l -f 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 experi- ments. By determining experimentally the vo- lume of vapour which a given volume of liquid can produce at 212, M. Gay-Lussac has happily solved the very difficult prob- lem of the specific 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 peculiar liquid, hermeti- cally 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 li- quid. He filled a tall graduated glass re- ceiver, 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 cy- linders was filled with water. Heat was applied by means of a convenient bath, till the water and the included mercury as- sumed the temperature of 212. The ex- pansible liquid had ere this burst the sphe- rule, expanded into vapour, and depressed the mercury. The height of the quicksilver column in the graduated cylinder above the level of the basin, being observed, it was easy to calculate the volume of the incum- bent vapour. The quantity of liquid used was always so small, that the whole of it was converted into vapour. The following exhibits the specific gravi- ties as determined by the above method: ( CAL Spec. Vapour of water, Hydroprussic acid, Absolute alcohol, Sulphuric ether, Hydriodic ether, Oil of turpentine, Carburet of sulphur, Muriatic ether, Grav. Air 1. 0.62349 0.94760 1.6050 2.5860 5.4749 5.0130 2.6447 2.2190 Thenard, Boiling point, Fahr. 212 79.7 173 96 148 316 116 52 The ahove specific gravities are estima- ted 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 va- pour at 212 Fahr. or 100 cent., the volvime is exactly the sum of what their separate volumes would have produced; so that the condensation by chemical action in the li- quid 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 tempe- ratures, 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 acci- dents which have happened, from a little water falling into heated oils. The little glass spherules, called candle bombs, ex- hibit 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; a number differing little from the above determination of M. Gay-Lussac. Desagulier's estimate of 14000 was there- fore extravagant. 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 con- veniently 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 du- ring condensation. Dr. Black, Mr. Watt, Lavoisier, Count Rum ford, Clement, and Desorrnes, as well as myself, have publish- ed observations on the subject. " In this research I employed a very simple appara- tus; and with proper management, 1 be- lieve, it is capable of giving the absolute quantities of latent heat in different va- pours, as exactly as more refined and com- plicated mechanisms. At any rate, it will afford comparative results with great pre- cision. It consisted of a glass retort of very small dimensions with a short neck, insert- ed into a globular receiver of very thin glass, and about three inches in diameter. The globe was surrounded with a certain quantity of water at a known temperature, contained in a glass basin. 200 grains of the liquid, whose vapour was to be exam- ined, were introduced into the retort, and rapidly distilled into the globe by the heat of an Argand lamp. The temperance of the jiir was 45, that of the water in the basin from 42 to 43, and the rise of tempera- ture, occasioned by the condensation of the vapour, jsever exceeded that of the atmos- phere by four degrees. By these means, as the communication of heat is very slow be- tween bodies which differ little in tempe- rature, I found that the air could exercise no perceptible influence on the water in the basin during the experiment, which was always completed in five or six minutes. A thermometer of great delicacy was continu- ally moved through the water; and its indi- cations 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 intro- duced material errors into the estimate. Hence,that distinguished philosopher found the latent heat of steam to be no more than 800 01- 810. Mr. Watt afterwards deter- mined it more nearly from 900 to 970; La- voisier 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 CAL CAL heat is entirely transferred to the refrige- ratory, where it is allowed to remain with- out apparent diminution for a few minutes. " In numerous repetitions of the same experiment the accordances were excellent The following 1 table contains the mean re- sults. 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 glob* by a slender ring fixed round the neck." For the arithmetical reductions I must refer to the paper itself. Dr. Thomson, in his com- ments on this part of my researches, ob- serves, " It is obvious, that the latent heats determined in this way must be considera- bly below the truth. The method contrived by Count Rumford seems to me a good deal better. He cooled the water surrounding the globe 4 below the temperature of the room, and continued the distillation till the temperature of the water was exactly 4 above that of the room." Surely Dr. Thom- son cannot have read the paper with atten- tion, or he would have perceived the fol- lowing sentence: "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." In fact, I left the glass basin of water repeatedly at a temperature of 4 above that of the room for double the duration of the experiment, and found scarcely a perceptible change in the ther- mometer immersed in it. This source of fallacy was sufficiently guarded against. But [ have found since, that a compensa- tion 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 corrected co- lumn: Table of Latent Heat of Vapours. Vapour of water, at its boiling point, Alcohol, pp. gr. 825, Ether, boiling point 112, Petroleum, Oil of turpentine, Nitric acid, sp. gr. 1.494, boiling point 165, Liquid ammonia, sp. gr. 0.978, Vinegar, sp. gr. 1.007, " Aqueous vapour of an elastic force ba- lancing the atmospheric pressure, has a specific gravity compared to air, by the ac- curate experiments of M. Gay-Lussac, of 10 to 16. For facility of comparison, let us call the steam of water unity, or 1.00; then the specific gravity of the vapour of pure ether is 4.00, while the specific gravity of the va- pour of absolute alcohol is 2.60. But the vapour of ether, whose boiling point is not 967 442 502.4 177.8 177.8 532. 837.3 875.0 Corrected column. 1000 457 312.9 183.8 1838 550. 865.9 903 tains some alcohol; hence we must accord- ingly diminish a little the specific gravity number of its vapour. It will then become, instead of 4.00, 3.55. Alcohol of 0.825 sp. gr. contains much water; sp. gr. of its vapour 2.30. That of water, as before unity, 1.00. The interstitial spaces in these vapours will therefore be inversely as these numbers, or g-jy for ether, -j-g-^- for alcohol, JJJ-Q for wa- ter. Hence, -yly of latent heat, existing in ethereal vapour, will occupy a proportional space, be equally condensed, or possess the same tension with -5^ in alcoholic, and -j-6"gazine.'\ * CAI.P. An argillo-ferruginous lime- stone.* * CAMELEON MINERAL. When pure potash and black oxide of manganese are fused together in a crucible, a compound is formed whose solution in water, at first green, passes spontaneously through the whole series of coloured rays to the red. From this latter tint, the solution may be made to retrograde in colour to the origi- nal 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 cir- cumstances. 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 vessels, containing azote, no cameleon is formed. The same result fol- lowed with the brown oxide, and ultimate- ly with the black. They therefore ascribe the phenomena to the absorption of oxygen, which is greatest when the oxide of man- ganese 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 tetrox- ide, or manganesic acid. When acids are poured upon the green cameleon, or an al- kali 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 came- leon 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 de- compose the cameleon, and an exposure to the air likewise produces the same effect. Soda, barytes, and strontites, also afford peculiar cameleons. The red potash ca- meleon is perfectly neutral. Phosphorus brought in contact with it produces a de- tonation; and it sets some other combusti- bles on fire. Exposed alone to heat, it is re- solved into oxygen, black oxide of manga- nese, and green cameleon, or submangane- siate of potash.* CAMPEACHY WOOD. See LOGWOOD. 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 distil- ling 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 be- comes condensed in the solid form among- the straw, and part comes over with the water. The sublimation of camphor is perform- ed in low flat-bottomed glass vessels placed in sand; and the camphor becomes con- crete in a pure state against the upper part, whence it is afterwards separated with a knife, after breaking the glass. Lewis as. serts 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 in- to a kind of cake. Chaptal says, the Hollan- ders mix an ounce of quicklime with every pound of camphor previous to the distilla- tion. Purified camphor is a white concrete crystalline substance, not brittle, but easily crumbled, having a peculiar consistence re- GAM sembling 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 residue. The roots of zedoary, thyme, rosemary, sage, the inula hellenium, the anemony, the pasque flower or pulsatilla, and (Tther vegetables, afford camphor by distillation. It is obsei-vable, 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 peppermint, slowly dried, af- ford much camphor; and Mr. Achard has observed, that a smell of camphor is disen- gaged when volatile oil of fennel is treated with acids. Mr. Kind, a German chemist, endeavour- ing 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 yel- low, then brown, and lastly, to be almost wholly coagulated into a crystalline mass, which comported itself in every respect like camphor. Tromsdorff and Boullay con- firm this. A small quantity of camphor may be obtained from oil of turpentine by sim- ple distillation at a very gentle heat Other essential oils, however, 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 communi- cates 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 ef- fected its solution in water by means of the carbonic acid. Camphor may be powdered by moisten- ing 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 gradu- ally adding the water. Yolk of egg and mucilages are also effectual for this pur- pose; but sugar does not answer well. It has been observed by Komieu, 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 se- parates 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 CAN for two days. A gentle heat was then ap- plied, 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 al- cohol each time, fifty -three grains of com- pact coal in small fragments remained un- dissolved. The alcohol, being evaporated in a water bath, yielded forty-nine grains of a blackish-brown substance which was bit- ter, astringent, had the smell of caromel, and formed a dark brown solution with wa- ter. This solution threw down very dark brown precipitates, with sulphate of iron, acetate of lead, muriate of tin, and nitrate of lime. It precipitated gold in the metal- lic 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 con- verts it into a peculiar acid. See ACID (CAMPHORIC). * Camphor melts at 288, and boils at the temperature of 400. By passing it in vapour through peroxide of copper, Dr. Thomson converted it into carbonic acid and water. He operated upon a single grain. He infers its composition to be Carbon, 0.738 8 at'ms. = 6.375 73.91 Hydrogen, 0.144 10 = 1.250 14.49 Oxygen, 0.118 1 = 1.000 11.60 1.000 8.625 100.00 As an internal medicine, camphor has been frequently employed in doses of from 5 to 20 grains, with much advantage; to pro- cure 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 temperature and the frequency of the pulse. In large doses it acts as a poison, an effect best counteract- ed by opium. It is administered to alleviate the irritating effects of cantharides, meze- reon, 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.* Dissolved in acetic acid, with some essential oils, it forms the aromatic vinegar, for which we are indebted to the elder Mr. Henry. It re- markably promotes the solution of copal. Its effluvia are very noxious to insects, on which account it is much used to defend subjects of natural history from their ra- vages. * CANCER, MATTER OF. This morbid secretion was found by Dr. Crawford to give a green colour to sirup of violets, and CAN TAG treated with sulphuric, acid, to emit, a gas resembling- sulphuretted hydrogen, which he supposes to have existed in combination with amiiraMa.in the ulcer. Hence the ac- tion of vmrlent pus on metallic salts. He likewise observed, that its odour was des- troyed by aqueous chlorine, which he there- fore recommends for washing cancerous sores.* \NDLES. Cylinders of tallow or wax, containing in their axis a spongy cord of cotton or hemp. A few years ago I made a set of experiments on the relative intensi- ties of light, and duration of different can- dles, the result 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. Economy of Light. Candles equal one argand. 10 mould. 10 dipped. 8 mould. 6 do. 4 do. Argand oil flame. 5h. 9 in. 4 36 6 31 7 2i 9 36 682 672 856 1160 1787 132 150 132 163 186 512 isi 13 10$ Hf 20i 69-4 68 65| 59 66 80 100 5.7 5.25 6.6 5.0 3.5 A Scotch mutchkin, or l-8th of a gallon of good seal oil, weighs 6010 gr. or 13 and l-10th oz. avoirdupois, and lasts in a bright argand lamp, 11 hours 44 min. 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 l-7th times the weight of tallow in candles, 6 to the pound. But its light, being equal to that of 5 of the latter candles, it appears from the above table, that 2 pounds weight of oil, value Is. in an argand, are equivalent in illuminating pow- er to 3 pounds of tallow candles, which cost about three shillings. The larger the flame in the above candles, the greater the eco- nomy of light.* * CANNEL COAL. See COAL.* * CANNON METAL. See COPPER.* "CANTHARIDES. Insects vulgarly called Spanish flies: lytta vesicatoria is the name adopted from Gmelin, by the London col- lege. This insect is two-thirds of an inch in length, one-fourth in breadth, oblong, and of a gold shining colour, with soft ely- tera or wing sheathes, 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 evapora- tion to dryness, and submitted for some time to the action of sulphuric ether, forms a yellow solution. By spontaneous evapora- tion crystalline plates are deposited, which may be freed from some adhering colour- ing matter by alcohol. Their appearance is like spermaceti. They are soluble in boil- ing alcohol, but precipitate as it cools. They do not dissolve in water. According to M. Robiquet, who first discovered them, these plates form the true blistering prin- ciple. They might be called VESICATO- RIN. Besides the above peculiar body, can- tharides contain, according to M. Robiquet, a green bland oil, insoluble in water, solu- ble in alcohol; a black matter, soluble in water, insoluble in alcohol, without blister- ing properties; a yellow viscid matter, mild, soluble in water and alcohol; the crystal- line plates; a fatty bland matter; phosphates of lime and magnesia; a little acetic acid, and much lithic or uric acid. The blister- ing fly taken into the stomach in doses of a few grains, acts as a poison, occasioning horrible satyriasis, delirium, convulsions, and death. Some frightful cases are related by Orfila, vol. i. part2d. Oils, milk, sirups, frictions on the spine, with volatile lini- ment and laudanum, and draughts contain- ing musk, opium, and camphorated emul- sion, are the best antidotes.* 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 Jatropha elastica, and Ur- ceola elastica. The juice is applied in successive coat- ings 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 ca- outchouc 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 ita CAO CAR most remarkable property: when warmed, as by immersion in hot water, slips of it may be drawn out to seven or eight times their original length, and will return to their former dimensions nearly Cold ren- ders it stiff and rig-id, 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 etheiyVo- Jatile oils, and petroleum. The ether, how- ever, requires to be washed with water re- peatedly, and in this state it dissolves it completely. Pelletier recommends to boil the caoutchouc 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 sulphuric ether in a vessel close stopped. In this way he says it will be totally dissolved in a few days, without heat, ex- cept the impurities, which will fall to the bottom, if ether enough be employed. Ber- niard says, the nitrous ether dissolves it better than the sulphuric. If this solution be spread on any substance, the ether evapo- rates very quickly, and leaves a coating of caoutchouc, unaltered in its properties. Naphtha, or petroleum, rectified into a co- lourless 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 drying. A solution of caout- chouc in five times its weight of oil of tur- pentine, and this solution dissolved in eight times its weight of drying linseed oil by boiling, is said to form the varnish of air- balloons. Alkalis act upon it so as in time to destroy its elasticity. Sulphuric acid is decomposed by it; sulphurous acid being 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 distil- lation it gives out ammonia, and carburet- ted hydrogen. Caoutchouc may be formed into various articles without undergoing the process of solution. If it be cut into a uniform slip of a proper 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 merely 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 afterwards applied with a small brxish on any surface, and dried by the sun or in the smoke, it will afford a pellicle of consider- able 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 ca- outchouc: it was used to make catheters and bougies, to varnish balloons, and for other purposes. Of the mineral caoutchouc there are se- rai varieties: 1 Of a blackish-brown inclin- ing to olive, soft, exceedingly compressi- ble, unctuous, with a slightly aromatic smell. It burns with a bright flame, leaving 1 a black oily residuum, which does not be- come dry. 2. Bls.ck, dry, and cracked on the surface, but, when cut into, of a yellow- ish-white. A fluid i-esembling pyrolignic acid exudes from it when recently cut. It is pellucid on the edges, and nearly of a hyacinthine red colour. 3. Similar to the preceding, but of a somewhat firmer tex- ture, and ligneous appearance, from having acquired consistency in repeated layers. 4. Resembling the first variety, but of a darker colour, and adhering to gray calca- reous spar, with some grains of galrcna. 5. Of a liver-brown colour, having the as- pect of the vegetable caoutchouc, but pass- ing by gradual transition into a brittle bi- tumen, of vitreous lustre, and a yellowish colour. 6. Dull reddish-brown, of a spongy or cork-like texture, containing blackish- gray nuclei of impure caoutchouc. Many more varieties are enumerated. One specimen of this caoutchouc has been found in a petrified marine shell en- closed in a rock, and another enclosed in crystallized fluor spar. The mineral caoutchouc resists the ac- tion of solvents still more than the vegeta- ble. The rectified oil of petroleum affects it most, particularly when by partial burn- ing it is resolved into a pitchy viscous sub- stance. A hundred grains of a specimen analyzed in the dry way by Klaproth, af- forded carburetted hydrogen gas 38 cubic inches, carbonic acid gas 4, bituminous 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. CARAT. See ASSAY. CARBON. When vegetable matter, parti- cularly 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 undergo 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-hundredth part, which consists chiefly of different saline and me- tallic 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- CAR CAR g-en 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 infer- red, 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 Lavoi- sier to be twenty-eight parts. From a care- ful experiment of Mr. Tennant, 27.t> parts of diamond, and 72.4 of oxygen, formed 100 of carbonic acid; and hence lie infer- red the identity of the diamond, and the inflammable part of charcoal. * Diamonds had been frequently con- sumed in the open air with burning glasses; but Lavoisier first consumed them in oxy- gen gas, and discovered carbonic acid to be the only result. Sir George Mackenzie showed, that a red heat, inferior to what melts silver, is sufficient to burn diamonds. They first enlarge somewhat in volume, and then waste with a feeble flame. M. Guyton Morveau was the first who dropped diamonds into melted nitre, and observed the formation of carbonic acid. From a number of experiments M. Biot has made on the refraction of different sub- stances, he has been led to form a differ- ent opinion. According to him, if the ele- ments of which a substance is composed be known, their proportions ma)' be calcula- ted with the greatest accuracy from their refractive powers. Thus he finds, tint the diamond cannot be pure carbon, but re- quires at least one-fourth of hydrogen, which has the greatest refractive power of any substance, to make its refraction com- mensurate to its density. In 1809, Messrs. Allen and Pepys made some accurate researches on the combus- tion of various species of carbon in oxygen, by means of an elegant apparatus of their own contrivance. Aplatinatube traversing a furnace, and containing a given weight of the carbonaceous substance, was con- nected at the ends with two mercurial gas- ometers, one of which was filled with oxy- gen gas, and the other was empty. The same weight of diamond, carbon, and plum- bago, yielded very nearly the same volume of carbonic acid. Sir M. Davy was the first to show that the diamond was capable of supporting its own combustion in oxygen, without the continued application of ex- traneous 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 exhibit- ed. If the diamond, supported in a per- forated 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 ig- nite the gem, and whilst in that state to introduce it into a globe or flask containing- oxygen. On turning off the hydrogen, the diamond enters into combustion, and will go on burning till nearly consumed. The loss of weight, and corresponding produc- tion of carbonic acid, were thus beautifully shown. A neat form of apparatus for this purpose is delineated by Mr. Faraday, in the 9ih 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 oc- casions, as in lining crucibles. It is insoluble in water, and hence the utility of charring the surface of wood ex- posed to that liquid, in order to preserve it, a circumstance not unknown to the an- cients. This preparation of timber has been proposed as an effectual 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. Heat- ed red-hot, or nearly so, it decomposes water; forming with its oxygen, carbonic acid, or carbonic oxide, according to the quantity present; and with the hydrogen a gaseous carburet, called carburetted hy- drogen, or heavy inflammable air. Charcoal is infusible by any heat. If ex- posed to a very high temperature in close vessels it loses little or nothing of its weight, but shrinks, becomes more compact, and acquires a deeper black colour. Recently prepared charcoal has a re- markable property of absorbing different gases, and condensing them in its pores, without any alteration 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, - 90 vols. Ditto muriatic acid, 85 Ditto sulphurous acid, 65 Sulphuretted hydrogen, 55 Nitrous oxide, 40 Carbonic oxide, - 35 Olefiant gas, 35 Carbonic oxide, - 9.42 Oxygen, - - - 9,25 Azote, - - - 7.5 Light gas from moist charcoal, 5.0 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 al- ways completed in 24 hours. This curious faculty, which is common to all porous bo CAR CAR dies, resembles 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 condensed. In the experiments of Messrs. Allen and Pe- pys, 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 re- markable property displayed by charcoals impregnated with gas, is that with sulphu- retted hydrogen, when exposed to the air or oxygen gas. The sulphuretted hydro- gen is speedily destroyed, and water and sulphur result, with the disengagement of considerable heat. Hydrogen alone has no such effects. When charcoal was exposed by Sir II. Davy to intense ignition in vacua, and in condensed azote, by means of Mr. Children's magnificent voltaic battery, it slowly volatilised, and gave out a little hydrogen. 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 pro- duction of diamond.* Charcoal has a powerful affinity for oxy- gen, whence its use in disoxygenating me- tallic oxides, and restoring their base to its original metallic state, or reviving the me- tal. Thus too it decomposes several of the acids, as the phosphoric and sulphuric, from which it abstracts 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 carburet, as observed by Dr. Priestley. A singular and important property of chat-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 Pe- tersburg!), though it had been long before recommended to correct the foetor of foul ulcers, and as an antiseptic. On this ac- count 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. Com- mon vinegar boiled with charcoal powder becomes perfectly limpid. Saline solutions, that are tinged yellow or brown, are ren- dered colourless in the same way, so as to afford perfectly white crystals. The impure carbonate of ammonia obtained from bones, is deprived both of its colour and fetid smell by sublimation with an equal weight of charcoal powder. Malt spirit is freed greeable flavour by distillation al; but if too much be used, from its from charcoal part of the spirit is decomposed. Simple maceration, for eight or ten days, in the proportion of about 1-UOth of the weight of the spirit, improves the flavour much. It is necessary, 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 as- certained by experiment on a small scale. The charcoal may be used repeatedly, by exposing it for some time to a red heat before 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 em- ployed to convert iron into steel by ce- mentation. It enters into the composition of gunpowder. In its finer states, as in ivory black, lampblack, &c. it forms the basis of black paints, Indian ink, and printers' ink. * The purest carbon for chemical pur- poses is obtained by strongly igniting lamp- black in a covered crucible. This yields, like the diamond, unmixed carbonic acid by combustion in oxygen. Carbon unites with all the common sim- ple combustibles, and with azote, forming a series of most important compounds. With sulphur it forms a curious limpid liquid called carburet of sulphur, or sul- phuret of carbon. With phosphorus it forms a species of compound, whose properties are imperfectly ascertained. It unites with hydrogen in two definite proportions, con- stituting- sub-carburetted and carburetted hydrogen gases. With azote it forms prus- sic 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 asso- ciated with silica and alumina. The prim- itive combining proportion, or prime equi- valent of carbon, is 0.75 on the oxygen scale.* * CARBON (MINERAL), is of a grayish- black colour. It is charcoal, with various proportions of earth and iron, without bi- tumen. It has a silky lustre, and the fibrous texture of wood. It is found in small quan- tities, stratified with brown coal, slate coal, and pitch coal.* * CARBONATES. Compounds of carbo- nic 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, derives some of its fundamental or prime proportions from the constitution of the carbonates, their analysis requires peculiat- CAR CAR precautions. In the Annals of Philosophy for October 181 7, I gave a description of a new instrument for accomplishing 1 this pur- pose with the minutest 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 dis- engage 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 carbonic 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 -j- 55 lime. MM. Aiken, 44 + 56 Dr. Marcet, 43.9 -f- 56.1 Dr. Wollaston, 43.7 + 56.3 M. Vauquelin, 43.5 + 56.5 M. Thenard, 43.28 -f 56 - 72 Dr. Thomson, 43.137 -f 56.863 If we deduce the equivalent of lime from the analysis of Dr. Marcet, so well known for his philosophical accuracy we shall have Lime = 35.1 to carb. acid 27.5 Dr. Thomson's is 36.25 to do. 27.5 I adduced the following experiment, se- lected from among many others, as capable of throwing light on the cause of these varia- tions: " 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 capil- lary, some dilute muriatic acid was put. The whole being poised in a delicate ba- lance, 100 grains of calc spar in rhomboi- dal fragments were introduced, and the stopper was quickly inserted. A little while after the solution was completed, the di- minution 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 al- low the dense gas to flow out, the diminu- tion became 43.3. Finally, on heating the body of the vessel to about 70, while the hollow stopper was kept cool, small bub- bles of gas escaped from the liquid, and the loss of weight was found to be 43 65, at which point it was stationary. This is a tedious process." The instrument which I subsequently employed is quick in its ope- ration, 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 If wide, bloAvn at one of its ends, while VOL. I. the other is open and recurved like a sy- phon. The straight part of the tube, be- tween the ball and bend, is about 7 inches long. The capacity, exclusive of the cur- ved part, is a little more than 5 cubic inches. It is accurately graduated into cu- bic inches and hundredth parts, by the successive additions of equal weights of quicksilver, from a measure thermometric 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 be- ginning of the stem. The point in the tube, which is a tangent to the surface of the mercury, is marked with a file or a dia- mond. Then 34^ grains, equal in volume to l-100th of a cubic inch, being drawn up into the thermometric tube, rest at a cer- tain height, which is also marked. The same measure of mercury is successively introduced and marked off, till the tube is filled. " In the instrument thus finished, l-200th of a cubic inch occupies on the stem about l-14th of an inch, a space very distinguisha- ble. The weight of carbonic acid, equiva- lent to that number, is less than l-400th of a grain. The mode of using it is perfectly simple and commodious, and the analytical result is commonly obtained in a few mi- nutes." For example, five grains of calcareous spar in three or four rhomboids were weighed with great care in a balance by Crighton, which turns with jp-eVoTT f the weight in the scales. These are" intro- duced into the empty tube, and made to slide gently along into the spheroid. The instrument is then held in nearly a hori- zontal position with the left hand, the top of the spheroid resting ag'ainst the breast, with a small funnel bent at its point, in- serted into the orifice of the tube. Quick- silver 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 mercury, they are discharged by inverting the instrument, 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 displaced by the cooled car- bonic acid, falls into a stone-ware or glass basin, within which the 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 34 CAB CAR syphon is brought to a level, or the differ- ence of height above the mercury in the ba- sin is observed, as also the temperature of the apartment, and the height of the baro- meter. Then the ordinary corrections being made, we have the exact volume of carbo- nic acid contained in five grains of calc spar In very numerous experiments, which 1 have made in very different circumstances of atmospherical pressure and tempera- ture, the results have not varied one-hun- dredth 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 exer- cised on mercury by dilute muriatic acid at ordinary temperatures; as no perceptible difference 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 carbonic acid from the mu- riate of lime, or other saline solution, by gently heating that point of the tube which contains it, it is evident that the total vo- lume of gaseous product must be accu- rately 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 wash- ed out and drained. According to my ex- periments with the above instrument, 5 grains of calcareous spar yield, 4.7 cubic inches of carbonic acid, equivalent to 43.616 percent. The difference between this num- ber 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 composi- tion of the sublimed carbonate; of ammo- nia, which chemists had previously mis- taken. I showed in the Annals of Philoso- phy for September 1817, that this salt con- tained 54.5 of carbonic acid, 30.3 ammo- nia, and 15 water, in 100 parts; numbers which, being translated into the language of equivalents, approach to the following proportions: Carbonic acid, 3 primes, 8.25 55.89 Ammonia, 2 4.26 28.86 Water, 2 2.25 15.25 14.76 100.00 As this volatile salt possesses the cu- rious 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 car- bonic acid-j-22.8 ammonia-j- 22.75 wa- ter =s 100. Now, if these numbers be re- ferred 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 equi- valent ratios in compounds of a variable nature, do not seem to have attracted no- tice at the time. Dr. Thomson describes in his System the solid subcarbonate found in the shops as indefinite in the proportion of its constituents. In the 14th Number of the Journal of Science, his friend, Mr. Phil- lips, whose attention to minute accuracy is well known, has published an ingenious pa- per on the subject, which begins with the following handsome acknowledgment of my labours: " During some late researches, my attention being directed to the compo- sition of the carbonates of ammonia, I be- gan, 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 circum- stances respecting the compounds in ques- tion, which have, I believe, hitherto escaped observation." Mr. Phillips's communication is valua- ble. It presents a luminous systematic view of the carbonates of ammonia and soda. Dr. Thomson, in his Annals for July 1820, enumerates that account of the carbonates of ammonia among the improvements made in 1819, without any allusion to my expe- riments on the ammoniacal salts, publish- ed in his own Magazine, nearly three years before he printed his retrospect. The indications of the above analytical instrument 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 deduce 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 appli- cation is more curious than useful, since a slight variation in the quantity of gas, as well as accidental admixtures of other sub- stances, are apt to occasion considerable errors. It determines, however, the nature and value of a limestone with sufficient practical precision. As 100 grains of mag- nesian 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 marls and com- mon limestones may be examined, by sub- jecting a certain number of grains, in a graduated syphon tube, to the action of a little muriatic acid over mercury. From the bulk of evolved gas, expressed in cubic inches and tenths, deduct l-20th, the remainder -will express the proportion of real limestone pre- sent in the grains employed* CAR CAR * CARBONATE of BARYTES. SeeWiTH- ERITE.* * CARBONATE of LIME. See CALCARE- OUS SPAR.* * CARBONATE of STRONTIAN. See STRONTIAN and HEAVY SPAR.* * CARBONIC ACID. See ACID CARBO- NIC.* * 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 can- not be formed by the chemist by the direct combination of its constituents; for at the temperature requisite for effecting a union, the carbon attracts its full dose of oxygen, and thus generates carbonic 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 introducing well calcined char- coal into a tube traversing a furnace, as is represented plate I. fig. 2.; and when it is heated to redness, passing over it back- wards and forwards, by means of two at- tached mercurial gasometers or bladders, a slow current of carbonic acid, we con- vert the acid into an oxide more bulky than itself. Each prime of the carbon be- comes now associated with only one of oxygen, instead of two, as before. The carbon acting here, by its superior mass, is enabled to effect the thorough satura- tion of the oxygen. If 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 strontites, with metallic filings or charcoal, the combined acid is resolved as before into the gaseous oxide of carbon. The most convenient mixture is equal parts of dried chalk and iron, or zinc filings. By passing a numerous succession of electric explo- sions through one volume of carbonic acid, confined over mercury, 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 theore- tical considerations, to be 0.96782, though Mr. Cruickshank's experimental estimate was 0.9569. As the gas is formed by with- drawing from a volume of carbonic acid half a volume of oxygen, while the bulk of the gas remains unchanged, we obtain its specific gravity 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 ori- ginal gases at 1.51961 and 1.10359. Hence 100 cubic inches weigh 29-f grains at mean pressure and temperature. This gas burns with a dark -blue flame. Sir H. Davy has shown, that though carbo- nic oxide in its combustion produces less heat than other inflammable gases, it may be kindled at a much lower tempera- ture. It inflames in the atmosphere, when brought into contact with an iron wire heated to dull redness, whereas carburet- ted hydrogen is not inflammable by a si- milar 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 combustibles, except potassi- um and sodium. When potassium is heat- ed 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 pre- scribed in our systematic works, for pro- curing the oxide of carbon. In some of them, a portion of carbonic 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 ba- rytes and iron filings, or of oxide of zinc, and previously calcined charcoal. The ga- seous product, from the first mixture, is pure oxide of carbon. Oxide of iron, and pure barytes, remain 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 sen- sation, which was succeeded by giddiness, sickness, acute pains in different parts of the body, and exti-eme debility. Some days elapsed before he entirely recovered. Since then, Mr. Witter of Dublin was struck down in an apoplectic condition, by breath- ing this gas; but he was speedily restored, by the inhalation of oxygen. See an inte- resting 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, discovered by Dr. John Davy, is formed, to which he gave the name of phosgene gas. I shall describe its properties in treat- ing 1 of chlorine. It has been called chloro- carbonic acid, though chlorocarbonous acid seems a more appropriate name.* * CARBUNCLE, a gem highly prized by the ancients, probably the alamandine. 3 *. variety of noble Garnet* CAR CAR CARBURET OF SULPHUR. Called also er tube. The liquid carburet occupies the sulphuret of carbon, and alcohol of sul- bottom of the receiver bottle, and may be phur. separated from the supernatant water, by This interesting liquid was originally ob- putting the whole into a funnel, whose tained by Lampadius in distilling a mixture tube is closed with the finger, and letting of pulverized pyrites and charcoal in an the denser brown carburet flow out below, earthen retort, and was considered by him whenever the distinction of the liquid into as a peculiar compound of sulphur andhy- two strata is complete. Thus obtained, the drogen. But MM. Clement and Desormes, carburet is always yellowish, containing a with the precision and ingenuity whidfdis- small excess of sulphur, which may be re- tinguish all their researches, first ascer- moved by distillation from a glass retort, tained its true constitution to be carburet- plunged in water, at a temperature of 115. ted sulphur; and they invented a process of It is now transparent and colourless, of a great simplicity, for at once preparing it, penetrating, fetid smell, and an acrid burn- and proving its nature. Thoroughly cal- ing taste. Its specific gravity varies from cined charcoal is to be put into a porcelain 1.263 to 1.272. According* to Dr. Marcet, tube, that traverses a furnace, at a slight it boils below 110; according to M. The- angle of inclination. To the higher end of nard at 113 F.; and the tension of its va- the tube, a retort of glass, containing sul- pour at 72 o is equivalent to a column of phur, is luted; and to the lower end is at- 12.53 inches of mercury. At 53.5, accord- tached an adopter tube, which enters into ing to Marcet and Berzelius, the tension is a bottle with two tubulures, half full of equivalent to a column of -7-4 inches, or water, and surrounded Avith very cold wa- one-fourth of the mean atmospheric pres- ter or ice. From the other aperture of the sure; hence one-third is added to the bulk bottle, a bent tube proceeds into the pneu- of any portion of air, with which the ii- matic trough. When the porcelain tube is quid may be mixed. A spirit of wine ther- brought into a state of ignition, beat is mometer, having its bulb surrounded with applied to the sulphur, which subliming colton cloth or lint, if dipped in sulphuret into the tube, combines with the charcoal, of carbon, and suspended in the air, sinks forming the liquid carburet. The conclu- from 60 to 0*. If it be put into the receiver sive demonstration of such an experiment \vas however questioned by M. Berthollet of an air pump, and a moderate exhaustion be made, it sinks rapidly from 60 to jun. and Cluzel. But MM. Berthollet, The- 81. If a tube containing mercury be treat- nard and Vauquelin, the reporters on M CluzePs memoir, having made some expe- riments 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, who confirmed the results of MM. Clement and Desormes, and added likewise several important facts. ed 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 without congealing; a conclusive proof that combination changes completely the con- If about ten parts of well calcined char- stitution of bodies, since two substances coal in powder, mixed with fifty parts of usually solid, form a fluid which we can- pulverixed native pyrites (bisulphuret of not solidify. When a lighted body approach- iron), be distilled from an earthen retort, es the surface of the carburet, it immedi- into a tubulated receiver surrounded with ately catches fire, and burns with a blue ice, more than one part of sulphuret of sulphurous flame. Carbonic and sulphurous carbon may be obtained. If we employ the acids are exhaled, and a little sulphur is elegant process of M. Clement, we must deposited. A heal of about 700 inflames take care that the charcoal be perfectly the vapour of the carburet. Oxygen dilated calcined, otherwise no carburet will be ob- by it over mercury explodes by the electric tained. In their early experiments, they at- spark, with a violent detonation. My eudi- tached to the higher end of the porcelain ometer is peculiarly adapted to the exhi- tube a glass one, containing the sulphur bition of this experiment. A portion of oxy- iri small pieces, and pushed these succes- gen being introduced into the sealed leg, sively forwards by a wire passing air-tight through a cork, at the tipper 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 sub- stance remains almost entirely in the adopt- 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 in- clination of the syphon. The expansion of volume can be now most accurately mea- sured by bringing the mercury to a level in each leg. The subsequent explosion occasions no CAR CAR danger, and a scarcely audible report. The result is a true analysis, if we have mixed oxygen saturated with the vapour at ordi- nary 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 cam- phor. 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 yellow pulveru- lent substance, which sublimes unaltered in close vessels, but is so deliquescent that it cannot be passed from one vessel to ano- ther without absorbing moisture. When heated in that state, crystals of hydrosul- phuret of ammonia form. The compound with lime is made by heating some quick- lime in a tube, and causing the vapour of carburet to pass through it. The lime be- comes incandescent at the instant of com- bination. When the carburet is left for some weeks in contact with nitro-muriatic acid, it is converted into a substance having very much the appearance and physical proper- ties of camphor; being soluble in alcohol and oils, and insoluble in water. This sub- stance is, according to Berzelius, a triple acid, composed of two atoms of muriatic acid, one atom of sulphurous acid, and one atom of carbonic acid. He calls it, muria- tico-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 sur- face. On admitting water, a greenish solu- tion of sulphuret. of potash is obtained, containing a mixture of charcoal. From its vapour passing through ignited muriate of silver, without occasioning 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 me- tallic solutions, precipitates of a peculiar kind, called carbo-sulphurets, are obtain- ed. The following is a table of the colours of the precipitates: Muriate of Cerium, White or yellowish- white. Sulphate of Manga- nese, Greenish-gray. Sulphate of Zinc, White. Perm uri ate of iron, Dark red. Submuriate of Anti- mony, Orange. Muriate of tin, Pale orange, then brown. Nitrate of Cobalt, Nitrate of lead, Nitrate of copper, Pro to muriate of mer- Dark olive-green, at last black. A fine scarlet. Dark brown. Black. cury, Permuriate of mer- cury, Orange. Muriate of silver, Reddish-brown. Carburet of sulphur was found by Dr. Brewster to exceed all fluid bodies in re- fractive power, and even the solids, flint- glass, topaz, and tourmaline. In dispersive power it exceeds every fluid substance ex- cept oil of cassia, holding an intermediate place between phosphorus and balsam of tola. The best method of analyzing the car- buret of sulphur, is to pass its vapour over ignited peroxide of iron; though the ana- lysis was skilfully effected by MM. Ber- thollct, Vauquelin, and Thenard, by trans- mitting the vapour through a red-hot cop- per tube, or a porcelain one containing copper turnings. Both the first method, as employed by Berzelius, 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 Mar- cet 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 ex- tract of a letter which he received from Mr. J. Murray, philosophical 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 ap- plied to the surface, instantly the globules became cased with a shell of icy spiculac 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 became 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."* * CARBURETTED HYDROGEN GAS. Of this compound g'us, formerly called heavy inflammable uir, we have two species, dif- fering in the proportions of the constitu- ents. The first, consisting of 1 prime equi- valent of each, is carburetted hydrogen; the second, of 1 prime of carbon, and 2 of hy- drogen, is subcarburetted hydrogen. l.Car- buretted hydrogen, the percarburetted by- CAR CAR drogen of the French chemists, is, accord- ing to Mr. Brande, the only definite com- pound of these two elements. To prepare it, we mix in a glass retort, 1 part of alco- hol, 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 hquid absorbs more than l-7th of its volume of the^ gas. It is destructive of animal life. Its specific gravity is U.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 temperature it depo- sites more charcoal, and augments 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 re- markable results, observed with great care, have induced the illustrious Berthollet to conclude, with much plausibility, that hy- drogen and carbon combine in many suc- cessive proportions. The transmission of a series of electric sparks through this gas, produces a similar effect with that of sim- ple heat. Carburetted hydrogen burns with a splendid white flame When mixed with three times its bulk of oxygen, and kind- led by a taper or the electric spark, it ex- plodes with great violence, 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 twc volumes of hydrogen. Hence the original volume of carburetted hydrogen was made up of these two volumes of hydrogen = 0.1398 (0.0694 X 2) -f 2 volumes of gase- ous carbon = 8333, constituting 1 con- densed volume = 0.9731. By gaseous car- bon is meant the vapour of this solid, as it exists in carbonic acid; the density of which vapour is found bv subtracting the specific gravity of oxygen, from that of carbonic acid. Hence 1.5 277 1.1111 = 0.4166, re- presents the density of gaseous carbon. M. Thenard says, that if we mix the percarbu- retted 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 danger. (See EUDIOMETER). When it is detonated with only an equal volume of oxygen, it ex- pands greatly, and the two volumes become more than three and a half. In this case on- ly l-8th or 1-1 Oth of a volume of carbonic 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 oxide. 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 con- sisting of 1 prime of each constituent. For 0.1398: 0.125: :8333: 0.752; now 0.125 and 0.750 represent the prime equivalents 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 compound. Hence this carburetted hydrogen was called by its discoverers, the associated Dutch chemists, olefiant gas. MM. Robiquetand Colin formed this liquid in considerable quantities, by making two currents of its constituent 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 spe- cific gravity is 2.2201. Its boiling point is 152. At 49 is vapour is said to be capable of sustaining a column of 24-f inches of mercury. The specific gravity of the va- pour is 3.-I434, compared to atmospheric air. But that quantity is the sum of the densities of chlorine and olefiant gas. It will consist therefore by weight of Olefiant gas, 0.9731 (2 X 0.875) 1.75 Chlorine, 2.4733 4.45 3.4464 6.20 or two primes of the first and one of the second. Its ultimate constituents are there- fore 1 chlorine, 2 carbon, and 2 hydrogen. This substance burns with a green flame, from which charcoal is deposited, and mu- riatic acid gas flies off. Decomposition, with similar results, is effected by passing the liquid through a red-hot porcelain tube. Its constitution probably resembles that of muriatic ether. Olefiant gas is elegantly analyzed by heating sulphur in it over mercury. One cubic inch of it, with 2 grains of sulphur, yields two cubic inches of sulphuretted hy- drogen, and charcoal is deposited. Now we know that the latter gas contains just its own volume of hydrogen. 2. Subcarburetted hydrogen. This gas is supposed to be procured in a state of defi- nite composition, from the mud of stagnant CAR CAR pools or ditches. We have only to fill a wide mouthed goblet with water, and in- verting it in the ditch-water, stir the bot- tom with a stick. Gas rises into the goblet. The fire-damp of mines 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, tbe quantity of which can be ascertained by analysis. By igniting acetate of potash in a gun-barrel, an ana- logous species of gas is obtained. Accord- ing to M. Berlhollet, the sp gr. of the car- buretted hydrogen from ditch mud, exclu- sive of the azote, 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 carbonic acid, while water is precipi- tated. We can hence infer the composition of subcarburetted hydrogen. For of the two volumes of oxygen, one remains gaseous in the carbonic acid, and another is condens- ed with two volumes of hydrogen into wa- ter 1 volume of vapour of carbon -}- 2 vo- lumes of hydrogen, condensed into 1 vo- lume, compose subcarburetted hydrogen gas. Thus in numbers, 1 volume of gaseous carbon = 0.4166 0.75 = 1 prime 2 do. hydrogen = 0.1398 (0.125 X 2) = 0.25 = 2 primes 0.5J64 Here we see the specific gravity 0.5564, is very near the determination of Berthol- let. We also perceive the compound prime to be 1.000, the same as oxygen. Berthol- let says that the carburetted hydrogen ob- tained 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 = 0.75 As the gas of ditches and the choke- damp of mines are evidently derived from the action of water on decaying vegetable or carbonaceous matter, we can under- stand that a similar product will be obtain- ed by passing water over ignited charcoal, or by heating moistened charcoal or vege- table matter in retorts. Th< j gases are here, however, a somewhat complex mixture, as well as what we obtain by igniting pit-coal and wood in iron retorts. (See COAL GAS). The combustion of subcarburetted hydro- gen with common air takes place only when they are mixed in certain propor- tions. If from 6 to 12 parts of air be mixed with 1 of carburetted hydrogen, we have explosive mixtures. Proportions beyond these limits will not explode. In like man- ner, from 1 to 2$ of oxygen, must be mix- ed with 1 of the combustible gas, other- wise we have no explosion. Sir H. Davy says that this gas has a disagreeable em- pyreumatic smell, and that water absorbs l-30th of its volume of it.* 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 re- garding the papaw tree, is the extraction from its juice of a matter exactly resem- 1.00 bling the flesh or fibre of animals, and hence called vegetable fibrin; which see. CARMi]s 7 E. A red pigment prepared from cochineal. See LAKE. * CAR N ELI AN 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 semi-transpa- rent, and has a glistening lustre. It consists of 94 silica, 3.5 alumina, and 0.75 oxide of iron. The finest specimens come from Cam- bay and Surat in India. It is found in the channels of torrents in Hindostan, in no- dules of a blackish olive, passing into gray. After exposure for some weeks to the sun, these are subjected to heat in earthen pots, whence proceed the lively colours for which they are valued in jewelry. It is softer than common calcedony.* * CAROMEL. The smell exhaled by su- gar, at a calcining heat.* CARTHAMUS, SAFFLOWER, or BAS- TARD SAFFRON. In some of the deep red- dish, yellow, or orange-coloured flowers, the yellow matter seems to be of the 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 particu- larly are the saffron-coloured flowers of car- thamus. These after the yellow matter has been extracted 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 saiflower, and from the countries whence it is commonly brought to us, Spanish red and China lake. This pigment impregnates alcohol with a beauti- ful red tincture; but communicates no co- lour to water. Rouge is prepared from carthamus. For this purpose the red colour is extract- ed by a solution of the subcarbonate of CAS CAT soda, and precipitated by lemon juice, pre- viously depurated by standing. This pre- cipitate 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 fineness of the powder and proportion of the precipi- tate 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 thec akes opened, it is put in- to 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 al- kali 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 large trough is filled. And this is repeated, with the addition of a little more alkali toward the end, till the carthamus is exhausted and becomes 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 proper colour; when it is brightened in hot water and lemon juice. For a poppy or fire colour a slight annotta ground is first given; but the silk should not be alumed. For a pale carnation 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, semi-transpa- rent, animal solid, which remains of the shape, and one-third the weight of the bones, when the calcareous salts are re- moved by digestion in dilute muriatic acid. It resembles coagulated 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 flexi- ble cartilage. Hence arise the distortions characteristic of this disease.* CASE-HARDENING. Steel when harden- ed 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, to- gether with the toughness of iron. These requisites arc united in the art of case- hardening, which does not differ from the making of steel, except in the shorter du- ration 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 ce- mentation is much shorter than when the whole is intended to be made into steel. Immersion of the heated pieces into water hardens the surface, which is afterward polished by the usual methods. Moxon's Mechanic "Exercises, p. 56, gives the fol- lowing receipt: Cow's horn or hoof is to be baked or thoroughly dried and pulver- ized. 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 iu 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 spe- cies of food.* * CASSAVA. An American plant, thej'a- tropha manihaty contains the nutritive starch cassava, curiously associated with a deadly poisonous juice. The roots ofjatropha are 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 nutritious quality. The whole solid matter is dried in smoke, ground, and made into bread.* *CASSius'spurple precipitate. See GOLD.* CASTOR. A soft grayish-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 con- sists 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 anti- spasmodic. CATECHU. A brown astringent substance formerly known by the name of Japan earth. It is a dry extract, prepared from the wood of a species of sensitive plant, the mimosa, catechu. It is imported into this CAW CEL country from Bombay and Bengal. Accord- ing- 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 cate- chu from either place differs little in its properties. Its taste is astringent, leaving behind a sensation of sweetness. It is al- most wholly soluble in water. Two hundred grains of picked catechu from Bombay afforded 109 grains of tan- nin, 68 extractive matter, 13 mucilage, 10 residuum, chiefly sand and calcareous earth. The same quantity from Bengal: tannin 9? grains, extractive matter 73, mu- cilage 16, residual matter, being sand, with a small quantity of calcareous and alumi- nous earths, 14. Of the latter the darkest parts appeared to afford most tannin, the lightest most extractive matter. The Hin- doos 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- portion of tannin, and Mr. Purkis found, that one pound was equivalent to seven or eight of oak bark for the purpose of tan- ning leather. As a medicine it has been recommended as a powerful astringent, and a tincture of it is used for this purpose, but its aqueous solution is less irritating. Made into troches with gum arabic and sugar, it is an elegant preparation, 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 Ers. A mineral of a beautiful appearance, brought from Ceylon. Its colours are gray, green, brown, red, of various shades. Its internal lustre is shining, its fracture imperfectly conchoidal, 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 c/uttoyant. It scratches quartz, is easily broken, and resists the blow-pipe. Its sp. gr. is 2.64. Its constituents are, ac- cording to Klaproth, 95 silica, 1.75 alumina, 1.5 lime, and 0.25 oxide of iron. It is va- lued for setting as a precious stone.* CAUSTIC (LUNAR.) Fused nitrate of sil- ver. See SILVER. CAUSTICITT. All substances which have so strong a tendency to combine with the principles of organized substances, as to de- stroy their texture, are said to be caustic. The chief of these are the concentrated acids, pure alkalis, and the metalic salts. * CAUTERY POTKN IAL. CAUSTIC.* GAWK. A term by which the miners Rs- VOL. I. tinguish the opaque specimens of sulphate of barytes. *CELESTIXE. Native sulphate of stron- tites. This mineral is so named from its oc- casional delicate blue colour; though it is frequently found of other shades, as white, grayish and yellowish -white, arid red. It occurs both massive and crystallized. Some- times also in fibrous and stellated forms. According to Haiiy, the primitive form is a right rhomboidal m-ism, of 104 48' and 75* 12'. The reflecting goniometer makes these angles 104 and 76. The varieties ot" 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. Jts sp. gr. is 3.6. Before the blow-pipe it fuses into a white, opaque, and friable enamel. The three subspecies are, 1st The com- pact found in Montmartre near Paris, of a yellowish -gray colour, in rounded pieces, ot" a dull lustre, opaque, and consisting, by Vauqueliri's analysis, ,of 91.42 sulphate o"f strontites, 8.33 carbonate of lime, and 0.25 oxide of iron. 2d, The fibrous, whose co- lours are indigo-blue and bluish-gray; some- times white. It occurs both massive and crystallized. Shining and some what pearly lustre. It is translucent. Sp. grav. 8.83. 3d, The foliated, of a milk-white colour, falling into blue. Massive and in grouped crystals, of a shining lustre and straight fo- liated kxiure. Translucent. Celestine oc- curs most abundantly near Bristol in the red marl formation; and crystallized in red sand- stone, at Inverness in Scotland. Mr. Gruner Ober Berg of Hanover has lately favoured the world with an analysis of a crystallized celestine, found in the neigbourhood of that city, of rather pecu- liar composition. 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- ties -{- 25 sulphate of barytes, we should have considered the mineral as a compound of 4 primes of the first salt -}- 1 of the se- cond. Now the analysis, in my opinion, can- not be confided in, within these limits; for the mingled muriates of the earths were se- parated by digestion in 16 times th^ir weight of boiling alcohol, of a strength not named. Besides, the previous perfect conversion of the sulphates into carbonates, by merely fu- sing the mineral with thrice its weight of carbonate of potash, is, to say the least, problematic?!. J)r. Thomson adapts M 1 33 CEM CEM her Bern's analysis to 7 atoms of sulphate of strontian, and 2 atoms of sulphate of ba- rytes.* CEATEXT. 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 SOL DEHS of every kind, which see; but it is more commonly employed to signify those of which the basis is an earth or earthyalt. -See LIME. We shall here enumerate, chiefly from the Philosophical Magazine, some cements 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 unite pieces of Derbyshire spar, or other stone. The stone should be made hot enough to melt the cement, and the pieces should be pressed tog-ether as close- ly as possible, so as to leave as little as may be of the cement between them. This is a general rule in cementing, as the thinner the stratum of cement interposed, the firm- er it will hold. Melted brimstone used in the same way will answer sufficiently well, if the joining be not required to be very strong. It sometimes happens, that jewellers, in setting precious stones, break off' pieces by accident; 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 pro- duce the appearance of an onyx. Mastic is likewise used to cement false backs or doub- lets to stones, to alter their hue. The jewellers in Turkey, who are gene- rally Armenians, ornament watch-cases and other trinkets with gems, by glueing them on. The stone is set in silver or gold, and the back of the setting made flat to corres- pond with the part to which it is to be ap- plied. It is then fixed on with the follow- ing cement. Isinglass, soaked in v ater 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 gal- baiuim, or gum ammoniacum, are dissolved in two ounces of this by trituration; and five or six bits of mastic, as big as peas, 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 mois- ture. A solution of shell lac in alcohol, added to a solution of isinglass in proof spirit, makes another cement that will resist mo sture. So does common g-lue melted without wa- ter, with half its weight of resin, with the addition of a little red ochre to give it a bu- dy. This is particularly useful for cement- ing hones to their frames. 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 ofT, it is to be washed in cold water, and then kneaded in warm water. This pro- cess 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 co)d, 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 con- sistence, 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 pivs- sure of steam. The proportions of the in- gredients are not material, but the more the red lead predominates, the sooner the cement will diy, 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 am- monia, 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 filing's, grind them to- gether in a mortar, mix them with water to a proper consistence, and apply them be- tween the joints. Powdered quicklime 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 ia iron boilers. Temporary cements are wanted in cutting, grinding, or polishing optical glasses, stones, and various small articles of jewvllery, which it is necessary to fix on blocks, or handles, for the purpose. Four ounces of resin, a quarter of on ounce of wax, and four ounces of whiting made previously red-hot, form a good cemment of this kind; as any of the CEM CER above articles may be fastened to it by heat- ing them, and removed at pleasure in the same manner, though they adhere very firm- ly 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 ramid.* * CHLORATES. Compounds of chloric acid with the ealifiable bases. See CHLORIC ACID.* CHL CHL -"* HLOHIC ACID. See ACID (CHLORIC).* * CHLOTHDKS. Compounds of chlorine with combustible bodies, bee 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 oxymuriatic acid gas of the French school, a substance which, j^i'ter resisting the most powerful means of de- composition 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 previous- ly imagined, and as its name seemed to denote. He accordingly assigned to it the term chlorine, descriptive of its colour; a name now generally used. The chloridic theory of combustion, though more limited in its applications to the chemical phenome- na of nature, than the antiphlogistic of La- voisier, may justly be regarded as of equal importance to the advancement of the sci- ence itself. When we now survey the Trans- actions of the Royal Society for "l 808, 1809, 1810, and 1811, we feel overwhelmed with astonishment at the unparalleled skill, la- bour, and sagacity, by which the great Eng- lish chemist, in 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 profound, original, and su- blime. The importance of the revolution produced by his researches on chlorine, will justify us in presenting a detailed account of the steps by which it has been effected. How entirely the glory of this great work belongs to Sir H. Davy, notwithstanding some inCi- dious attempts in this country, to tear the well-earned laurel from his brow, and trans- fer it to the French chemists, we may rea- dily 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 inter- esting extracts. In the Bakerian lecture for 1808," says he, " i have given an account of the action oi potassium upon muriatic acid gas, by which more than one-third of its volume of hydr>gcn is produced; and I have stated, that uuriatic acid can in no instance be pro- cured from oxymuriatic acid, or from dry muriates, unless water or its elements be present. " In the second volume of the Memoir es D'Arcueil, MM. Gay-Lussac and Thenard have detailed an extensive series of facts up- on muriatic acid, and oxymuriatic acid. Some of their experiments are similar to those 1 have detailed in the paper just re- ferred to; others are peculiarly their own, and of a very curious kind; their general conclusion is, that muriatic acid gas contains about one quarter of its weight of water; and that oxymuriatic acid is not decomposa- ble by any substances but hydrogen, or such as can form triple combinations with it. ' One of the most singular tacts that I have observed on this subject, and which I have before referred to, is that charcoal, even when ignited to whiteness in oxymu- riatic 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 ignition in vacua. This experiment, which I have several times repeated, led me to doubt of the ex- istence of oxygen in that substance, which has been supposed to contain it, above all others, in a loose and active state; ana to make a more rigorous investigation, than had hitherto been attempted for its detec- tion.' 1 He then proceeds to interrogate nature, with every artifice of experiment and rea- soning, till he finally extorts a confession of the true constitution of this mysterious mu- riatic 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 for 1811, present the whole body of evidence for the undecompounded nature of oxymuriatic acid gas, thenceforward sty led 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 hypo- thesis of Lavoisier, that combustion was mere- ly 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 incombustible, imparting that inflammability to the new substance, which its former com- panion had secretly lost. Stahl's idea of com- bustion is the more comprehensive, and may still be true; Lavoisier's as a general propo- sition, is certainly false.f In 1812 Sir H. Davy published his Ele- ments of Chemical Philosophy; containing a systematic account of his new doctrines con- cerning the combination of simple bodies. f It appears to me that Stahl's doctrine is false, both as a general and particular pro- position. According to him, metals are com- pounds of their own oxides, now known to be compounds containing metals as ingredients; and this error was extended to explain the relation between every combustible, and its compounds formed with oxygen. The doctrine of Stahl never can be true, until it ceases to be an axiom, that the less earmot contain the greater. CHL CHL Chlorine is there placed in the same rank muriatic gas as a compound body." Thi with oxygen, and finally removed from the pressure of public opinion becomes conspi- class of acids. In 18 i3, M. Thenard pub- cuous at the end of the rolume. Among the lished the first volume of his Traitf de Chi- additions, we have the following decisive mie Elementaire Theorique et Pratique. This evidence, of the lingering attachment to the distinguished chemist, the fellow-labourer of o ld theory of Lavoisier and Berthollet .--" A M. Gay-Lussac, in those able researches on p re tty considerable number of persons who the alkalis and oxymurialic acid, which form the honourable rivalry of the French school to the brilliant career of Sir H. Davy, states at page 584. of the above volume, the com- position ofoxymuriatic acid as follows: " Corn- have subscribed for this work, desiring a de tailed explanation of the phenomena, which oxygenated muriatic gas presents, on the supposition that this gas is a simple body, we are now going to explain these pheno- mena, on this supposition, by considering them attentively. The oxygenated muriatic - ,, - -.- x .. . gas will take the name of chlorine; its com- rnunatic acid. It thence tollows, that it is " L - _..-^i i __ _._i_i ~.,..^ position. The oxygenated muriatic i^as, con- tains the half of its volume of oxygen gas, not including that which we may suppose in formed of 1.9183 of muriatic acid, and 0.5517 of oxygen; for the specific gravity of oxyge- nated muriatic gas is 2.47, and that of oxy- gen gas, 1.1034." " M. Chenevix first de- termined the proportion of its constituent principles. MM. Gay-Lussac and Thenard determined it more exactly, and showed that we could not decompose the oxygenated muriatic gas, but by putting it in contact 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 binations with phosphorus, sulphur, azote, metals, will be called chlorures; the muriatic acid, which results from equal parts in vol- ume of hydrogen and oxygenated muriatic gases, will be hydrochloric add; the super- oxygcnated muriatic acid, will be chlorous acid; and the hyperoxygenated muriatic, chloric acid; the first, comparable to the h)driodic acid, and the last to the iodic acid." In fact, therefore, we evidently see, that so far from the chloridic theory origin- ating in France, as has been more than insinuated, it was only the researches on could explain all the phenomena which it iodine> so admirably conducted by M. Gay- presents, by considering it as a simple, or Lussac that by their auxiliary attack of the ' oxygen hypothesis, eventually opened the minds of its adherents, to the evidence long ago advanced by Sir H. Davy. It will be peculiarly instructive, to give a general outline of that evidence, which has been mutilated in some systematic works on che- mistry, or frittered 'away into fragments. as a compound body. However, this last opinion appeared more probable to them. M. Davy on the contrary, embraced the first, admitted it exclusively, and sought to fortify it, by experiments 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 Sir H. Davy subjected oxymuriatic gas, to the action of many simple combustibles, as well as metals, and from the compounds j . / i ' i <*a wen as mc.wi, uuu. iiuiii v.uc ijwuiuwuuu* demontrer par ce dernier proceue que e fopmed endeavoured to eliminate oxygen, gas munatique oxtgene doit contemn 14 by the most ener getic powers of affinity and moitie de son volume doxigene, um a ^ u ., ;f , ^i Pt wr.;+ v . K..t unthmit ci.o^ss. an 1'acide muriatique." P. 147. In the 4th volume which appeared in 1816, we find the following passages: " Oxygenated mu- riatic gas. Oxyg'enated muriatic gas, in combining with the metals, gives ris< the neutral muriates. Now, 107.6 of oxide voltaic electricity, but without success, the following abstract will show. If oxymuriatic acid gas be introduced in- to a vessel exhausted of air, containing tin; and the tin be gently heated, and the gas in combining with the metals, gives rise to suffic i ent quantity, the tin and the gas dis- the neutral muriates. Now, 107.6 of oxide aopear . and a limpid fl u j d> precisely the of silver, contain 7.6 of oxygen, and absorb same as L ibavius's liquor is formed: If this 26.4 of muriatic acid, to pass to the^state su b sta nce is a combination of muriatic acid of neutral muriate. Of consequence, 348 of and ox j de o f tin, oxide of tin ought to be this last acid supposed dry, and 100 of oxy- separated from it by means of ammonia. gen, form this gas. But the sp. gr. of oxy- jj e admitted ammoniacal gas over mei-cury gen is 1.1034, and that of oxygenated mu- t o a small quantity of the liquor of Libavius; riatic gas is 2.47; hence, this contains the it was absorbed with great heat, and no gas : gas half of its volume of oxygen." P. 52. The force of Sir H. Davy's demonstra- tions, pressing for six years on the public mind of the French philosophers, now be- gins to transpire in a note to the above passage. " We reason here," says M. Thenard, "obviously, on the hypothesis, which consists in regarding oxygenated VOL. I. - . gas was generated; a solid result was obtained, which was of a dull white colour: some of it was heated, to ascertain if it contained oxide of tin; but the whole volatilized, pro- ducing dense pungent furnes. Another experiment of the same kind, made with great care, and in which the am- monia was used in great excess, proved that 36 CHL CHL the liquor of Libavius cannot be decom- pounded by ammonia; but that it forms a new combination with this substance. He made a considerable quantity of the solid compound of oxymuriatic acid and phosphorus by combustion, and saturated it with ammonia, by heating it in a proper re- ceiver filled with ammoniacal gas, on which it acted with great energy, producing much heat; and they formed a white opaque pow- der. Supposing that this substance was composed of the dry muriates and phos- phates of ammonia; as muriate of ammonia is very volatile, and as ammonia is driven off from phosphoric acid, by a heat below red- ness, he conceived that, by igniting the pro- duct obtained, he should procure phosphoric acid; he therefore introduced some of the it to redness, out of the contact of air, by a spirit lamp; but found, to his great surprise, that it was not at all volatile nor decomposa- ble 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 pro- perties 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 a high degree of purity, and oxymuriatic acid gas, both dried, in equal volumes. In this instance the condensation was not 40; sulphur, which seemed to contain a little oxymuriatic acid, was formed on the sides of the vessel; no vapour was deposited; and 19 the residual gas contained aboui^ of muri. atic acid gas, and the remainder was inflam- mable. When oxymuriatic acid is acted upon by nearly an equal volume of hydrogen, a com- bination takes place between them, and mu- riatic acid gas results. When muriatic acid gas is acted on by mercury, or any other metal, the oxymuriatic acid is attracted from the 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 com- pounds, which have been usually considered as muriates, or as dry muriates, but which are properly 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 Libavius's liquor, a solid crys- tallized mass is obtained, from which oxide of tin and muriate of ammonia can fre pro- cured by ammonia. In this case, oxygen may be conceived to be supplied to the tin, and hydrogen to the oxymuriatic acid. The compound formed by burning phos- phorus in oxymuriatic acid, is in a similar relation to water. If that substance be add- ed to it, it is resolved into two powerful acids; oxygen, it may be supposed, is fur- nished to the phosphorus to form phosphoric acid, hydrogen to the oxymuriatic acid to form common muriatic acid gas. He caused strong explosions from an electrical 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 phos. phorus and sulphur for some hours, by the power of the voltaic apparatus of 1000 dou- ble 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 ob- tained hydrogeTi from Libavius's liquor by a similar operation. But he ascertained that this was owing to the decomposition of wa- ter adhering to the mercury; and in some late experiments made with 2000 double plates, in which the discharge was from pla- tina 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 ten- dency of combination is with pure inflam- mable matters, 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 differ- ing from them, in being for the most part decomposable by water? On this idea mu- riatic acid may be considered as having hy- drogen for its basis, and oxymuriatic acid for its acidifying principle. And the phosphoric sublimate as having phosphorus for its basis, and oxymuriatic acid for its acidifying matter. And Libavius's liquor, and the compounds of arsenic with oxymuriatic acid, may be regard- ed as analogous bodies. The combinations of oxymuriatic acid with lead, silver, mer- cury, potassium, and sodium, ia this view, would be considered as a class of bodies re- lated more to oxides than acids, in their powers of attraction. Hak. Lee. 1809. On the Combinations of the Common Metals icith Oxygen and Oxymuriatic Gas. Sir H. used in all cases small retorts of CHL CHL green glass, containing from three to six cu- bical inches, furnished with stop-cocks. The metallic substances were introduced, the re- tort 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 examined, and the residual gas ana- lyzed. All the metals he tried, except silver, lead, nickel, cobalt, and gold, when heated, burnt in the oxymuriatic gas, and the vola- tile metals with fLtme. Arsenic, antimony, tellurium, 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; platina was scarcely acted upon at the heat effusion 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 oxy- muviatic 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 has been absorbed by the metal^ Thus two grains of red oxide of mercury ab* sorbed- -of a cubical inch of oxymuriatic gas, and afforded 0.45 of oxygen. Two grains of dark olive oxide from calomel de- composed by potash, absorbed of oxymuriatic gas, and afforded of oxy. gen, and corrosive sublimate 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 absorbed. 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 was given off' in either case, but butter of arsenic and arsenical acid formed in one in- stance, and the ferruginous sublimate and red oxide of iron in the other. General Conclusions and Observations, illus- trated by Experiments. Oxymuriatic gas combines with inflam- about- mable bodies, to form simple binary com- pounds; and in these cases, when it acts upon oxides, it either produces the expulsion of their oxygen, or causes it to enter into new combinations. 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 peroxides 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 oxymuriatic gas; for this, on such an as- sumption, should consist of muriatic acid (on the old hypothesis, free from water) and phosphorous acid; but tin's substance has no effect on litmus paper, and does not act under common circumstances on fixed alkaline bases, such as dry lime or magne- sia. Oxymuriatic gas, like oxygen, must be combined in large quantity with pecu- liar inflammable matter, to form acid mat- ter. In its union with hydrogen, it instantly 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 quan- tity of oxygen is given off from a body not known to be compound, when we are cer- tain of its existence in another; and all the cases are parallel. Scheele explained the bleaching powers of the oxymuriatic gas, by supposing that it destroyed colours by combining with phlogiston. Berthollet considered it as act- ing by supplying oxygen. He made an ex- periment, 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 de- composing water, and liberating its oxygen. He filled a glass globe, containing dry powdered muriate of lime, with oxymuri- atic gas. He introduced some dry paper tinged with litmus that had been just heat- ed, into another globe containing dry mu- riate 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 in- CHL CHL to gas that had not been exposed to mu- riate of lime, was instantly rendered white. It is generally stated in chemical books, that oxymuriatic gas is capable of being condensed and crystallized at a low tem- perature. He found by several experiments that this is not the case. The solution of oxy- muriatic gas in water freezes more readi- ly than pure water, but the pure gas dnjed by muriate of lime undergoes no change whatever, at a temperature of 40 below of Fahrenheit. The mistake seems to have arisen from the exposure of the gas to cold in bottles containing moisture. He attempted to decompose boracic and phosphoric acids by oxymuriatic gas, but without success; from which it seems pro- bable, that the attractions of boracium and phosphorus for oxygen are stronger than for oxymuriatic gas. And from the experi- ments already detailed, iron and arsenic are analogous in this respect, and proba- bly some other metals. Potassium, sodium, calcium, strontium, barium, zinc, mercury, tin, lead, and proba- bly 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 contain oxygen, and which cannot contain muriatic acid, oxymuriatic acid, is contrary to the principles of that nomenclature in which it is adopted; and an alteration of it seems necessary to assist the progress of discussion, and to diffuse just ideas on the subject. If the great discoverer of this sub- stance had signified it by any simple name, it would have been proper to have recur- red to it; but dephlogisticated marine acid is a term which can hardly be adopted in the present advanced era of the science. After consulting some of the most emi- nent chemical philosophers in this country, it has been judged most proper to suggest a name founded upon one of its obvious and characteristic properties its colour, and to call it chlorine, or chloric gas. 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 be- ing converted into a true muriate." Eak. Lee. 1811. We shall now exhibit a summary view of the preparation and properties of chlo- rine. Mix in a mortar 3 parts of common salt and 1 of black oxide of manganese. Intro- duce them into a glass retort, and add 2 parts of sulphuric acid. Gas will issue, which must be collected in the water-pneu- matic trough. A gentle heat will favour its extrication. In practice, the above pasty - consistenced mixture is apt to boil over in- to the neck. A mixture of liquid muriatic acid and mang'anese is therefore more con- venient for the production of chlorine. A very slight heat is adequate to its expul- sion from the retort. Instead of manganese, red oxide of mercury, or puce-coloured ox- ide of lead, may be employed. This gas, aa we have already remarked, is of a greenish-yellow colour, easily recog- nized by day-light, but scarcely distinguish- able by that of candles. Its odour and taste are disagreeable, strong, and so charac- teristic, 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, constriction of the thorax, and a copious discharge from the nostrils. If respired in larger quantity, it excites violent coughing, with spitting of blood, and would speedily destroy the individual, amid violent distress. Its specific gravity is 2.4733. 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 confin- ing it over mercury. One volume of hydro- gen, added to one of chlorine, form two of the acid gas. Hence, if from twice the specific gravity of muriatic gas = 2 5427, we subtract that of hydrog-en = 0.0694, the difference 2-4733 is the speci- fic gravity of chlorine. 100 cubic inches at mean pressure and temperature weigh 75 grains. See GAS. In its perfectly dry state, it has no effect on dry vegetable colours. With the aid of a little moisture, it bleaches them into a 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 ra- pidly 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 me- tals, as well as copper, tin, arsenic, zinc, antimony, in fine laminae or filings, spon- taneously burn in chlorine. Metallic chlo- rides 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 li- quid 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 nee- dles, at 40 Fahr. According to M. Thenard, water con- denses, at the temperature of 68 Fahr. CHL CHL and at 29.92 barom. 1 times its volume of chlorine, and forms aqueous chlorine, for- merly called liquid oxymuriatic acid. This combination is best made in the second bottle of a Woulfe's apparatus, the first be- ing- charged with a little water, to inter- cept 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 corres- pond to 2 and l-3d libs, avoirdupois, and from 21 to 25 pints English. There is an ingenious apparatus for making aqueous chlorine, described in Berthollet's Ele- ments 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 manu- facture. 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. Hence when chlorine is passed into water at tem- peratures under 40, the liquid finally be- comes a concrete mass, which at a gentle heat liquefies with effervescence, from the escape of the excess of chlorine. When steam and chlorine are passed together through a red-hot porcelain tube, they are converted into muriatic acid and oxygen. A like result is obtained by exposing aque- ous chlorine to the solar rays; with this dif- ference, that a little chloric acid is formed. Hence aqueous chlorine should be kept in a dark place. Aqueous chlorine attacks al- most all the metals at an ordinary tempe- rature, forming muriates or chlorides, and heat is evolved. It has the smell, taste, and colour of chlorine; and acts like it, on ve- getable 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 chlorine 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 chemical 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 ab- sorbability 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 sunbeam. If exposed at first to this intensity of light, it explodes with great violence, and instant- ly forms muriatic acid gas. The same ex- plosive combination is produced by the electric spark and the lighted taper. M. Thenard says, a heat of 392 is sufficient to cause the explosion. The proper pro, portion is an equal volume of each gas Chlorine and nitrogen combine into a re-, markable detonating compound, by expos- ing the former gas to a solution of an am- moniacal salt. See NITROGEN. Chlorine is the most powerful agent for destroying contagious miasmata. The disinfecting phi- als of Morveau evolve this gas. See CHLO- ROUS OXIDE.* f * CHLORITE is a mineral usually friable or very easy to pulverize, composed of a multitude of little spangles, or shining small grains, falling to powder under the pressure of the fingers. There are four sub-species. 1. Chlorite earth. In green, glimmering and somewhat pearly scales, with a shining green streak. It adheres to the skin, and has a greasy feel. Sp. gr. 2.6. It consists of 50 silica, 26 alumina, 1.5 lime, 5 oxide of iron, 17.5 potash. This mineral is found chiefly in clay-slate, in Germany and Switzerland. At Altenberg, in Saxony, it is intermingled with sulphurets of iron and nrsenic; and amphibole in mass. 2 Com- mon chlorite. A massive mineral of a black- ish-green colour, a shining lustre, and a fo- liated fracture passing into earthy. Streak is lighter green; it is soft, opaque, easily cut and broken,. and feels greasy. Sp. gr. 2.83. Its constituents are 26 silica, 18.5 alumina, 8 magnesia, 4;> 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-foli- ated fracture. Double cleavage. Easily cut. Feels somewhat greasy. Sp gr 2.82. It occurs particularly along with clay-slate, and is found in Corsica, Fahlun in Sweden, and Norway. 4. Foliated chlorite Colour between mountain and black ish-green. Massive; but commonly crystallized in six- sided tables, in cylinders terminated by two cones, and in double cones with the bases joined. Surface streaked. Lustre shining pearly; foliated fracture, translucent on the edges; soft, sectile, and folia usually flexi- ble. Feels rather greasy. Sp. gr. 2.82. It is found at St. Gothard, in Switzerland, and in the island of Java. Us constituents are 35 silica, 18 alumina, 29.9 magnesia, 9.7 oxide of iron, 27 water.* * CHLOROPHANE A violet fuor spar, found in Siberia.* * CHLORO-CARBONOUS ACID. The term f It is surprising, that I have no where met with any mention of one of the most distinctive and obvious properties of this gas. When the exterior air was about the temperature of 60, and a mercurial ther- mometer detected no difference between the temperature of the chlorine and that of the surrounding medium, the hand, im- mersed in it, would experience a sensa- tion of warmth, indicating 80 or 90. CHL CHL chloro-carbonic which has been given to this compound is incorrect, leading- to the belief of its being a compound of chlorine and acidified charcoal, instead of being- a compound of chlorine and the pi-otoxide of charcoal. Chlorine has no immediate ac- tion on carbonic oxide, when they are ex- posed to each other in common day-light over mercury; 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 di- rect solar beams, and one volume of each is condensed into one volume of the com- pound. The resulting- gas possesses very curious properties, approaching to those of an acid. From the peculiar potency of the sunbeam in effecting this combination, Dr. Davy called it phosgene gas. The con- stituent gases, dried over muriate of lime, ought to be introduced from separate re- servoirs 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 dis- appears, and on opening the stop-cock be- longing to the globe under mercury re- cently boiled, an absorption of one-half the gaseous volume is indicated. The resulting gas possesses properties perfectly distinct from those belonging to either carbonic oxide or chlorine. It does not fume in the atmosphere. Its odour is different from that of chlorine, something like that which might be ima- gined to result from the smell of chlorine combined with that of ammonia. It is in fact more intolerable and suffocating than chlorine itself, and affects the eyes in a peculiar manner, producing a rapid flow of tears, and occasioning painful sensations. It reddens dry litmus paper; and con- denses four volumes of ammonia into a white salt, while heat is evolved. This am- moniacal compound is neutral, but has no odour, but a pungent saline taste; is deli- quescent, decomposable by the liquid mi- neral acids, dissolves without effervescing in vinegar, and sublimes unaltered in mu- riatic, 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, heuted in chloro-carbonous acid, abstract the chlorine, and leave the carbonic oxide expanded to its original volume. There is neither ignition nor explosion 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 carbo- nic acid. Neither sulphur, phosphorus, oxy- gen, nor hydrogen, though aided by heat, produce any change on the acid gas. But oxygen and hydrogen together, in due pro- portions, explode in it; or mere exposure to water, converts it into muriatic and car- bonic acid gases. From its completely neutralizing ammo- nia, which carbonic acid does not; from its separating carbonic acid from the subcar- bonate of this alkali, while itself is not se- parable 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 condenses so large a proportion of ammonia. One measure of alcohol condenses twelve of chloro-carbonous gas without decompos- ing 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 gravity of its constituents, of which it is the sum. Hence 2.4733 -f 0.9722 = 3.4455, is the specific gravity of chloro- carbonous gas; and 100 cubic inches weigh 105.15. grains. It appears that when hydro- gen, carbonic oxide, and chlorine, 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 investiga- tions on the subject at the same time, but without success. M. Thenard has, however, recognized its distinct existence and pro- perties, by the name of carbo -muriatic acid, in the 2d volume of his System, published in 1814, where he considers it as a com- pound of muriatic and carbonic acids, re- suiting from the mutual actions of the oxy- genated muriatic acid, and carbonic oxide.* * CHLOROUS and CHLORIC OXIDES, or the protoxide and deutoxide of chlorine. Both of these interesting gaseous com- pounds were discovered by Sir H. Davy. 1st, The experiments which led him to the knowledge of the first, were instituted in consequence of the difference he had observed between the properties of chlo- rine, prepared in different modes. The pa- per describing the production and proper- ties of the chlorous oxide, was published in the first part of the Phil. Trans, for 1811. 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. CHL CHL Its tint is much more lively, and more yellow than chlorine, and hence its illus- trious 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. \Vater absorbs 8 or 10 times its vo- lume of this gas. Its specific gravity is to that of common air nearly as 2.40 to 1; for 100 cubic inches weigh, according to Sir H. Davy, between 74 and 75 grains. If the compound gas result from 4 volumes of chlorine -j- 2 of oxygen, weighing 12.1154, which undergo a condensation of one-sixth, then the specific gravity comes out 2.42.), in accordance with Sir H. Davy's expe- riments. He found that 50 measures deto- nated in a glass tube over pure mercury, lost their brilliant colour, and became 60 measures; of which 40 were chlorine, and 20 oxygen. Dr. Thomson states 2.407 for the sp. gr., though his own data, when rightly calculated upon, give 2.444. This gas must be collected and examined with much prudence, and in very small quantities. A gentle heat, even that of the hand, will cause its explosion, with such force as to burst thin glass. From this fa- cility of decomposition, 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 tem- peratures; but when the oxygen is sepa- rated, they then inflame in the chlorine. This may be readily exhibited by first in- troducing 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 instantly 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. Protoxide 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 volumes of chlorine and one of oxygen; and a chloride and acid of phosphorus result. Lighted taper and burning 1 sulphur likewise instantly decom- pose it. When the protoxide freed from water is made to act on dry vegetable co- lours, 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 ap- proaching to sour, it may be considered as approximating to an acid in its nature. Since 2 volumes of chlorine weigh (2 X 2.4733) 4.9466, and 1 of oxygen 1.1111; we have 4.45 -f- 1. = 5.45 for the prime equi- valent Of chlorous oxide, on {lie oxygen scale. The proportion by weight in 100 parts is 81.65 chlorine -{- 18.35 oxygen. 2d, Deut oxide of Chlorine, or Chloric Ox- ide. " 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 fi oin the salt is held in solution by the acid. After various unsuccessful attempts to ob- tain 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 boiling 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 red- dening them. When phosphorus is intro- duced into it, an explosion takes place. When heat is applied, the gas explodes with more violence, and producing more light than euchiorine. 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 isfcomposed of one atom chlorine and four atoms oxygen." I have transcribed the above abstract of Sir II. Davy's paper from the number of Dr. Thomson's Annuls for June 1815, in or- der to confront it with the following- state- ment in his System, 5th edition, vol. i, page 189: " The deutoxide of chlorine was dis- covered about the same time by Sir Hum- phry Davy and Count Von Stadion of Vi- enna; but Davy's account of it was publish- ed sooner than that of Count Von Stadion. Davy's account is published in the F'hiloso- phical Transactions for 1815, p. 214. Count Von Stadion's in Gilbert's Annalen der Phy- sick, 52. 179. published in February, 1816." Sir H. Davy's paper bears date " Rome, February 15th, 1815." There is therefore an interval of fully twelve months between the transmission of Sir H. Davy's discovery for publication, and the promulgation of Count Von Stadion's paper; and an in- terval of nine months between the actual publication of the first, by the reading of it before the Royal Society of England, and the appearance of the second, in Gil- bert's Annalen. I do not wish to insinuate CHL CHR that the Count copied from the English philosopher; but 1 maintain, that according to every principle of literary justice, the reputation of the discovery entirely belongs to Sir H. Davy. Even the volume of the Transactions for 1815, which one is left to infer might come forth only in 1816, must have been pub- lished earlier, for Tilloch's Magazine ^for December 1815, contains the whole of Sir H. Davy's paper. The preceding abstract, circulated over Europe seven or eight months before the 52d volume of Gilbert's Annalen appeared is so copious as to require few additions. 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 explo- sion of the gas. Hence the small deficiency of the resulting measure is accounted for. At common temperatures none of the sim- ple combustibles which Sir H Davy tried, decomposed the gas, except phosphorus. The taste of the aqueous solution is ex- tremely astringent and corroding, leaving for a long while a very disagreeable sensa- tion. The action of liquid 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 sul- phuric. 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 min- gled gases, of which two are oxygen and one chlorine; its composition by weight is Oxygen, 2.2222 4 primes, 4.00 47,33 Chlorine, 2.4733 1 do. 4.45 52.67 8.45 100.00 Its specific gravity is 2.3477; and hence 100 cubic inches of it weigh about 77 grains. Having completed the account of this in- teresting compound, it may be worth while to copy a note from the 190th page of Dr. Thomson's 1st volume, to show the con- sistency of his opinions, in one leaf of his System. " According to Count Von Stadion, its constituents are two volumes chlorine, and three volumes oxygen. This would make it a compound of one atom chlorine, and three atoms oxygen. But the proper- ties of the substance described by the Count differ so much from those of the gas examined by Davy, that it is probable they are distinct substances." So that after all, Count Von Stadion has got a deutoxide of chlorine to himself, without interfering with Sir. H. Davy's property. We shall leave him to enjoy it, with the following intima- tion by his commentator: " The reader will find an account of the properties of the deutoxide of chlorine of Count Von Stadion, in the Annals of Philosophy, vol. ix. p. 22." 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 afterwards treating it with alcohol. A mat- ter was dissolved, which when separated by evaporation, and purified by washing in hot water, appeared as a deep green resin- ous substance. It dissolves entirely in alco- hol, ether, oils, or akalis; 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 dis- solves it. Acetic acid is the only acid that dissolves it in great quantity- If an earthy or metallic salt be mixed with the alco- holic 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 proximate principle. The above learned term should be spel- led with a y, chiorophyle, 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, 6.66 oxygen, and 21.33 hydrogen, by Be- rard. CHOLESTERIC ACID. By heating choles- terine with its own weight of strong nitric acid until it ceases to give off nitrous gas, MM. Pelletier and Caventou obtained a yellow substance, which separated on cool- ing, and was scarcely soluble in water. When well washed, this is cholesteric acid. It is soluble in alcohol, and may be crystal- lized by evaporation. It is decomposed by a heat above that of boiling water, and gives products having oxygen, hydrogen, and charcoal, for their elements. It com- bines with bases, and forms salts. Those of soda, potash, and ammonia, are very solu- ble; the rest are nearly insoluble. * CHROMIUM. This rare metal may be extracted either from the native chromate of lead or of iron. The latter being cheap- est and most abundant, is usually employ- ed. The brown chromate of iron is not acted upon by nitric acid, but most readily by ni- trate of potash, with the aid of a red heat. A chromate 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 diges- tion in dilute muriatic acid. A second fu- sion with ^th of nitre, will give rise to a new portion of chromate of patash. Having decomposed the whole of the ore, we satu- CHR CHE, rate the alkaline excess with nitric acid, evaporate and crystallize. The pare crys- tals dissolved in water, are to be added to a solution of neutral nitrate of mercury; whence by complex affinity, red chromate of mercury precipitates. Moderate ignition expels the mercury from the chromaie, and the remaining' chromic acid may be re- duced to the metallic state, by being 1 ex- posed, in contact of the charcoal from su- gar, to a violent heat. Chromium thus procured, is a porous mass of agglutinated grains. It is very brit- tle, and of a grayish-white, intermediate between tin and steel. It is sometimes ob- tained in needleform crystals, which cross each other in all directions. Its sp. gravity is 5.9. It is susceptible of a feeble magnet- ism. It resists all the acids except nitro- muriatic, which, at a boiling heat, oxidizes it and forms a muriate. M. Thenard de- scribes only one oxide of chromium; but there are probably two, besides the acid already described. 1. The protoxide is green, infusible, in- decomposable by heat, reducible by voltaic electricity, 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 tiie air, burns with fhime, and is transformed into chromate of potash or soda, of a canary-yellow colour. It is this oxide which is obtained by calcining the chromate of mercury in a small earthen retort for about of an hour. The beak of the retort is to be surrounded with a tube of wet linen, and plunged into water, to fa- cilitate the condensation of the mercury. The oxide, newly precipitated from acids, has a dark green colour, and is easily re- dissolved; 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 al- tered. 2. The deutoxide is procured by expos- ing- the protonitrate to heat, till the fumes of nitrous gas cease to issue. A brilliant brown powder, insoluble in acids, and scarcely soluble in alkalis, remains. Mu- riatic acid digested on it, exhales chlorine, showing the increased proportion of oxy- gen in this oxide. 3. The tritoxide has been already descri- bed among the acids. It may be directly i procured by adding nitrate of lead to the 'above nitrochromate of potash, and digest- ing the beautiful orange precipitate of chromate of lead with moderately strong muriatic acid, till its power of action be ex- hausted. The fluid produced is to he pass- ed through a filter, and a little oxide of ' silver, very gradually added, till the whole VOL. 1. solution becomes of a deep red tint. This liquor, by slow evaporation, depositcs small ruby-red crystals, which are the hydrated 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. Ac- cording 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 -f 7.088, metal; while the protoxide would consist of 3 oxygen-J-7 088 metal; and the deutox- ide, of an intermediate proportion.* * CHRYSOBERYL. Cymophcwt: of Hatty. 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, conchoi- dal; it is semi-transparent, and brittle, but scratches quartz and beryl. Sp. gr 3.76. It is infusible before the blow-pipe. It has double refraction, and becomes electric by friction. Its primitive form is a rectangular parallelopiped. Its constituents, according to Klaproth, are 71 alumina, 18 silica, 6 lime, and 1 oxide of iron. The summits of the p:isms of chrysobe- ryl, 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 no- thing to do with the chrysoberyl of Pliny, which was probably a variety of beryl of a greenish-yellow colour.* CHRYSOCOLLA. The Greek name for borax. *CHRYSOLITE. Peridot of Hatty. Topaz 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 com- pressed prisms, of eight sides at least, ter- minated by a wedged form or pyramidal summit, truncated at the apex. Its primi- tive form is a right prism, with a rectan- gular base. It has a strong double refrac- tion, 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 co- lour is pistachio green, and other shades. External lustre splendent. Transparent; fracture, conchoidal. Scratches feldspar. Brittle. Sp gr. 3.4. With borax, it fuses in- to 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 Ixen found in Bohemia, and in the circle of Bunzlau.* * CHRYSOPRASE. A variety of calcedony. 57 CHY CIN It is either of an apple or leek-green colour. Its fracture is even, waxy, sometimes a lit- tle 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 co- lour. It has been found hitherto only* at Kosemiitz in Upper Silesia. The mountains which enclose it, are composed chiefly of serpentine, potstone, talc, snd other unctu- ous 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 Saus- sure 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 babbles. It dissolves entirely and without effervescence in acids.* * CHYLE. By the digestive process in the stomach of animals, the food is converted into a milky fluid, called chyme, which pass- ing into the intestines is mixed with pan- ereatic juice and bile, and thereafter re- solved into chyle and feculent matter. The former is taken up by the lacteal absorbent vessels of the intestines, which coursing along the mesenteric web, terminate in the thoracic duct. This finally empties its con- tents 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 separates by coagulation into a thicker and thinner matter. l.The former, or curd, seems intermediate 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 dissolves the coagu- lum; and very weak nitric acid changes it into adipocere. By heat, it is converted in- to a charcoal of difficult incineration, which contains common salt and phosphate of lime, with minute traces of iron. 2. From the serous portion, heat, alcohol, and acids, precipitate a copious coagulum of albumen. If the alcohol be hot, a little matter analo- gous to the substance of brain is subse- quently deposited. By evaporation and cool- ing, Mr. Brande obtained crystals analo- gous to the sugar of milk. Dr. Marcet found the chyle of graminivorous animals thinner and darker, and less charged with albumen, than that of carnivorous. 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 nei- ther 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.* ClMOLITK, Or ClMGT.IAN EARTH. The cimolia of Pliny, which was used both me- dicinally 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 grayish-white colour, ac- quiring superficially a reddish tint by ex- posure 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 g'ravitv is 2. It is immediately pe- netrated by water, and deve'opes itself into thin laminae of a curved slaty form. Tritu- rated with water it forms a pappy mass; and 100 grains will give three ounces of water the appearance and consistence of a thick ish 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 si- lex 63, alumina 23, oxide of iron 1.25, wa- ter 12. Ground with water, and applied to silk and woollen, greased with oil of almonds, 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 combination with the alu- mina. It is still used by the natives of Ar- gentiera 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 decomposition of the porphyries, occasion, ed 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. 1. The red is in large, easily pulverized CIN pieces, which furnish a reddish-brown pow- der, 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 extractive, resin, bitter principle, and tannin. 2. The yellow Peruvian burk,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 kinate of lime in plates. 3 The pale cinchona is that generally em- ployed in medical practice, as a tonic and febrifuge. M. Vauquelin made infusions of all the varieties of cinchona he could pro- cure, using the same quantities of the barks and water, and leaving the powders infus- ed for the same time. He observed, 1. That certain infusions were precipitated abun- dantly by infusion of galls, by solution of glue, and tartar emetic. 2. That some were precipitated by glue, but not by the two other reagents; and 3. That others were, on the contrary, by nutgalls and tartar emetic, without being affected by glue. 4. And that there were some which yielded no precipi- tate by nutgalls, tannin, or emetic tartar. The cinchonas that furnished the first infu- sion were of excellent quality; those that afforded the fourth were not febrifuge, while those that gave the second and third, were febrifuge, but in a smaller degree than the first. Besides mucilage, kinate of lime, and woody fibre, he obtained in his analyses, a resinous substance, which ap- pears not to be identic in all the species of bark. It is very bitter; very soluble in alco- hol, in acids and alkalis; scarcely soluble in cold water, but more soluble in hot. It is this body which gives to infusions of cin- chona, 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 precipi- tations by glue, tannin, and tartar emetic, from infusions of different barks, has been given by M. Vauquelin; but as the particu- lar species are difficult to define, we shall not copy it.* CINCHONIN. See the preceding article. CINNABAR. An ore of mercury, consist- ing of that metal united with sulphur. * CINNAMON STONE. The colours of this rare mineral are blood-red, and hya- cinth-red, passing into orange-yellow. It is found always in roundish pieces; lustre splendent; fracture imperfect conchoidal; fragments angular; transparent and semi- transparent; scratches quartz with difficul- ty; somewhat brittle; sp. gr. 3.53; fuses in- to a brownish-black enamel. Its constitu- ents are 38.8 silica, 21.2 alumina, 31.25 lime, and 6.5 oxide of iron. It is found in the sand of rivers, in Ceylon.* CLA CIPOLIN. The cipolin from Rome is a green marble with white zones: it gives fire with steel, though difficultly. One hun- dred parts of it contain 67.8 of carbonate of lime; 25 of quartz; 8 of schistus; 0.2 of iron, beside the iron contained in the schis- tus. The cipolin from Autun, 83 parts car- bonate of lime, 12 of green mica, and one of iron. *CISTIC OXIDE A peculiar animal pro- duct, discovered by Dr. Wollaston. It con- stitutes 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 oxycoccns, or cranberry, vaccinhtm vitisidtea t or red whortleberry, of birdcherry, night- shade, hip, in unripe grapes and tamarinds. Gooseberries, currants, bilberries, beam- berries, cherries, strawberries, cloudber- ries, and raspberries, contain citric acid mixed with an equal quantity of malic acid. The onion yields citrate of lime. See ACID (CITRIC).* CIVET is collected betwixt the anus and the organs of generation of a fierce carni- vorous quadruped met with in China and the East and West Indies, called a civet- cat, but bearing a greater resemblance to a fox or marten than a cat. Several of these animals have been brought into Holland, and afford a consi- derable 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 cli- mates Good civet is of a clear yellowish OP brownish colour, not fluid, nor hard, but about the consistence 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 resin- ous.* CLARIFICATION is the process of free- ing a fluid from heterogeneous matter or feculencies, though the term is seldom ap- plied to the mere mechanical pi-ocess of straining, for which see FILTRATION. Albumen, gelatin, acids, certain salts, lime, blood, and alcohol, in many cases serve to clarify fluids, that cannot be freed from their impurities by simple per- colation. Albumen or gelatin, dissolved in a small portion of water, is commonly used for CLA CLA fining vinous liquors, as it inviscates the feculent matter, and gradually subsides with it to the bottom Albumen is parti- cularly used for fluids, with which it will combine when cold, as sirups; it being- co- agulaied 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 aflbu men they contain is probably the agent. A couple of handful* of marl, 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 atten- tion. The argillaceous minerals are all suf- ficiently 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 considera- ble tenacity, which hardens with heat, so as to strike fire with steel. Marls and chalks also soften in water, but their paste is not tenaceous, nor docs 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 porcelain furnace. It is of a pure white, verging sometimes upon the yellow or flesh-red. Some present particles'of mi- ca, which betray their origin to be from feldspar or graphic granite. It scarcely ad- heres to the tongue. Sp. gr. 2.J. It is found in primitive mountains, amid blocks of granite, forming interposed strata. Ka- olins are sometimes preceded by beds of a micaceous rock of the texture of gneiss, but red and very friable. This remarkabe disposition has been observed in the kaolin quarries of China, in those of Alenc_on, and of Saint Yriex near Limoges. The consti- tuents of kaolin are 52 silica, 47 alumina, O.j.3 oxide of iron; but some contain a not- able 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 dis- appears in the fire, and therefore is not ow- ing to metallic impregnation. At Saint Yriex the kaolin is in a stratum and also in a vein, amid blocks of granite, or rather the feldspar rock, which the Chinese call petuntze. The Cornish kaolin is very white and unctuous to the touch, and obviously is formed by the disintegration of the feld- spar of granite. 2. Potters' clay, or plastic clay 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-gray colour; prin- cipal fracture imperfectly conchoidal, cross fracture earthy; fragments tabular, rather light, and feels more greasy than common potters' clay. Vauquelin's analysis of the plastic clay of Forge s-les-Eaux, employed 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 si- lica, with 3.5 lime. 3. Loam. This is an impure potters' clay mixed with mica and iron ochre. Colour yellowish-gray, 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 inferior to the pre- ceding. 4. Variegated clay. Ts striped or spotted with white, red, or yellow colours. Mas- sive, with an earthy fracture, verging on slaty. Shining streak. Very soft, some- times even friable. Feels slightly greasy, and adheres a little to the tongue. Sectile. It is found in Upper Lusatia. 5. Slate clay. Colour gray, or grayish- yeliow. Massive. Dull or glimmering lus- tre, from interspersed mica. Slaty fracture, approaching sometimes to earthy. Frag- ments 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 gray, of various shades, sometimes red, and spotted or striped. Massive. Dull lustre, with a fine earthy fracture, 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 Pentium! hills in Scotland, and in Germany. 7. Adhesive slate Colour light greenish- gray. Internal lustre dull; fracture in the large, slaty; in the small, fine earthy. Frag- CLA CLI merits slaty. Opaque. Shining- streak. Sec- tile. K,asily 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 Mont- martre near Paris, between blocks of im- pure gypsum, in larg-e straight plates like sheets of pasteboard. It is found also at Menil Montant, enclosing menilite. K lap- roth's analysis is 62.5 silica, 8 magnesia, 0.5 alumina, 0.25 lime, 4 oxide 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. Mas- sive. Lustre dull. Slaty fracture. Frag- ments tabular. Very soft, and adheres to the tongue. Smooth, but meagre to the touch. Sp. gT. in its dry state 0.6; when imbued with moisture 1.9. It has been found orily in Bohemia. Its constituents are 79 silica, 1 alumina, 1 lime, 4 oxide of iron, and 14 water. 9. Common clay may be considered to be the same as foam Besides the above, we have the analyses of some pure clays, the results of which show a verv minute quan- tity of silica, and a large quantity of sul- phuric acid. Thus, in one analyzed by Hu- cholz, 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 1935 sulphuric acid in 100 parts. We must re- gard these clays as sub-sulphates of alu- mina. CLAY SLATE. Argillaceous Schistus the Argillite of Kirwan. Colour, bluish-gray, and grayish black of various shades. Mas- sive. Internal lustre shining or pearly. Frac- ture foliated. Fragments tabular. Streak, greenish-white. Opaque. Soft. Sectile. Ea- sily 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 peroxide of iron, 0.5 oxide of manga- nese, 4.7 potash, 0.3 carbon, 0.1 sulphur, 7.6 water and volatile matter. Clay-slate melts easily by the blow-pipe into a shining- scoria. This mineral is extensively distri- buted, forming a part of both primitive and transition mountains. 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.* * CLIMATE. The prevailing constitu- tion of the atmosphere, relative to heat, wind, and moisture, peculiar to any region. This depends 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 iO feet under the surface, preserve a uniform temperature through all the vicissitudes of the season. This is the mean temperature of this coun- try From a comparison of observations, Professor Mayer constructed the following empirical rule for finding the relation be- tween the latitude and the mean tempera- ture, 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 centesimal ly with very great precision, by half the sine of double- the latitude. Mean Height of curve Latitude. temperature*. of congelation Cent. Fahr. in feet. C 2G 84.2 15207 5 28.78 83.8 15095 10 28.13 82.6 14764 15 27.06 80.7 14220 20 25.61 78.1 13478 25 2.3.82 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 11.98 536 6334 55 9.54 49.2 5034 60 7.25 45.0 3818 65 5.18 41.3 2722 70 339 38.1 1778 75 1.94 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 re- sults 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 large and strong- bulbs of the thermometers were buried in the ground at various depths, while the stems rose above the surface, for inspection. CLI CLI 1816. 1817. I foot. 2 feet. 3 feet. 4 feet. I foot. 2 feet 3 feet. 4 feet. January, 33 i 36.3 -*U.7 43 35.6 38.7 40.5 45.1 February, 33.7 36 390 42 37.0 40.0 41.6 42.7 March, 35 36.7 39.6 42.3 39.4 40.2 41.7 42.5 April, 39.7 38.4 41.4 43.8 45.0 424 42.6 42.6 May, 44.0 43.3 46.4 44.0 46.8 44.7 44.6 44.2 .'une, 51.6 50.0 47.1 45.8 51.1 ! 49.4 47.6 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, 10.8 43.8 46.3 45.6 41.0 44.7 1 47.0 47.6 December, 35.7 40.0 43.0 46.0 37.9 i 40.8 : 44.9 46.4 . ,. iMean ot whole year. 43.8 44.1 45.1 46. 44.9 45.9 46.2 46.6 Had the thermometers been sunk deep- er, 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 waters at the surface indicated respec- tively 64 and 68 Fahr. Barlocci observ- ed, that the Lago Sabatino, near Rome, at the depth of 490 feet, was only 44^, while the thermometer stood on its surface at 77. Mr. Jardine has made accurate obser- vations on the temperatures of some of the Scottish lakes, by which it appears, that the temperature continues uniform all the year round, about 20 fathoms under the surface. In like manner, the mine of Dan- nemora in Sweden, which presents an im- mense excavation, 200 or 300 feet deep, was observed at a period when the work- ing 1 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 Kongsberg in Norway, about 300 feet deep, is covered with perpetual snow. Hence, likewise, in the deep crevices on JEina. 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 cold- er, in consequence of the increased capaci- ty for heat of the air, by the diminution of the density. In the milder climates, it will be sufficiently accurate, in moderate eleva- tions, to reckon an ascent of 540 feet for each centesimal degree, or 100 yards for each degree on Fahrenheit's scale, of di- minished temperature. Dr. Francis Bu- chanan found a spring at Chitlong, 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 elevation of that valley. At the height of a mile this rule would give about 33 feet too much. The decrements of tem- perature augment in an accelerated pro- gression 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 moun- tain is no more than 4380 feet; and there- fore, during two or three weeks in July, the snow disappears. The curve of conge- lation must evidently rise higher in sum- mer, and sink lower in winter, producing a zone of fluctuating ice, in which the gla- ciers are formed. In calculating the mean temperature of countries at different distances from the equator, the warmth has been referred solely to the sun. But Mr. Bald has pub- lished, in the first number of the Edin- burgh Philosophical Journal, 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 t county of Cumberland. Air at the surface, - A spring at the surface, Water at the depth of 480 feet, Air at same depth, ... Air at depth of 600 feet, - Difference between water at surface and at 480 feet, 11 Workington Colliery, county of Cumberland. Air at the surface, 56 A spring at the surface, - - 48 55 F. 49 60 63 66 GLI CLI Water 180 feet down, - - 50 F. Water 504 feet under the level of the ocean, and immediately beneath the Irish sea, ... 60 Difference between water at surface and bottom, .... 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 = 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, - - 68 Air at the same depth, 70 At this depth Leslie's hygrometer in- dicated dryness = 83. Difference between mean tempera- ture of water at surface = 49, and at 900 feet down, - - 19 Jarrow 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 tempe- rature 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. Killing-worth 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, and at the great depth of 1200 feet from the surface, 74 Air at 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, - 210$ M. Humboldt has stated, that the tem- perature of the silver mine of Valenciana in New Spain is 11 above the mean tem- perature of Jamaica and Pondicherry, and that this temperature 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 ex- traordinary elevation of temperature ob- served by Mr. Bald. He further remarks, 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 horsedrivers from being an- noyed by the dust. This fact is adverse to the hypothesis of the heat proceeding from the chemical 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 per- petual 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 accura- cy and regularity in various parts of the world, will soon, it is hoped, make us bet- ter acquainted with the various local causes which modify climates, than we can pre- tend to be at present. The accomplished philosophical traveller, M. de Humboldt, published an admirable systematic view of the mean temperatures of different places, in the third volume of the Memoirs of the Society of Arcueil. His paper is entitled, of Isothermal Lines (lines of the same tem- perature), and the Distribution of Heat over the Globe. By comparing a great num- ber 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 sun-rise and two hours af- ter 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 cul-- tivated plants, depends less upon mean tem- perature, than upon direct light, and the serenity of the atmosphere; but \vhcat 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 eas- tern. The same difference that we observe on the two sides of the Atlantic, exists on the two sides of the Pacific. 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 winter of Copenhagen; Quebec 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 CLI CLI between the eastern coasts of Asia and of America, sufficiently proves, that the in- equalities of the seasons, depend upon the prolongation and enlargement of the conti- nents towards the pole, and upon the fre- quency of N. W. winds, and not upon the proximity of any elevated tracts of coun- try. Ireland, says Humholdt, presents orft of the most remarkable examples of the com- bination of very mild winters with cold summers; the mean temperature in Hunga- ry for the month of Ausrust is 71.6; while in Dublin it is only 60.t>. In Belgium and Scotland, the winters are milder than at Milan. In the article Climate, Supplement to the Encyclopaedia Britannica, the following ve- ry simple rule is given, for determining the change of temperature produced by sudden rarefaction or condensation of air. Multi- ply 25 by ihe difference between the density of air, and its reciprocal, the product will be the difference of temperature o?i the centigrade scale. Thus, if the density be twice, or one half 25 X (22) 37i 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 T V). But M. Gay-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 112.6, for the heat produced by a condensation into one-fifth. It appears very probable, that the cli- mates of European countries were more severe in ancient times than they are at present. Caesar says, that the vine could not be cultivated in Gaul, on account of its winter-cold. The rein-deer, now found on- ly in the zone of Lapland, was then an in- habitant of the Pyrenees. The Tiber was frequently frozen over, and the ground about Rome covered wilh snow for several weeks together, which almost never hap- pens in our times. The Rhine and the Dan- ube, in the reign of Augustus, were gene- rally frozen over, for several months of winter. The barbarians who overran the Roman empire a few centuries afterwards, transported their armies and wagons across the ice of these rivers. The improvement that is continually taking place in the cli- mate of America, proves, that the power of man extends to phenomena, which from the magnitude and variety of their causes, seemed entirely beyond his controul. At Guiana, in South America, within five de- grees 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 thun- ders continually in the woods, 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 omitted to notice an astronomical cause of the progressive amelioration of the climates of the northern hemisphere. In consequence of the apogee -portion of the terrestrial orbit being contained be- tween our vernal and autumnal equinox, our summer half of the year, or the interval which elapses between the sun's crossing- 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 hemis- phere.* Isothermal Sands, and Distribution of Heat, over the Globe. The temperatures are expressed in de- grees of Fahrenheit's thermometer; the lon- gitudes are counted from east to west, from the first meridian of the observatory of Paris. The mean temperature of the sea- sons has been calculated, so that the months of December, January, and Feb- ruary, form the mean temperature of the winter. The mark * is prefixed to those places, the mean temperatures of which have been determined with the most pre- cision, generally by a mean of 8000 obser- vations. The isothermal curves having a concave summit in Europe, and two con- vex summits in Asia and Eastern America, the climate is denoted to which the indivi- dual places belong 1 : CLI CLI 2 i a ? C-3OVOOOO o >-> >O VO O -"0 -O 'O q 3 -? rjj oq CM o -j; O O O> O O; O to CO ^rj * oq p CM co so o -f; TH oo 06 -* *o co bl -f- o? r-J bl ~i o 06 c4 x> r>j ^d co 06 -* rj* oo co -* rj oo ai co ai -o -o N! ai 10 'O CO b- >O CM l o> to' Nl N^ o *r> CM" CM" ^o d I-H co o> to rH JCMCMCOCOCOCOCOCOCOCMCO^COCOCO-* CO O O CM *O *H O O* OCM co CO e vj tq q to O CO Q} Q^ rH^COO to q co cq to H? N- t^* t^- ^^ ^ *O oq tq ^ss to 05 q o co *^ cS co rH Tjl 00 CO CO CO CO CO CO CO CO CO CO CO CO CM CO -^ -# ^ cr> * >/ q cq *-O ^* ^ 00 Q"> CO -* ^* * ^ ro ^ CO ^ vo to "* q c>> CM CO CM rH O V5 twt, rHdrHddrHTHrHCOCOCOTjJvrjirj^tO o - t>- CO r-i CO ^ C* CO CO <* * T-l CO CN rH * ^ co co CM-HO -HO fs. rH rH CM O O> CO O CO rH CM 8 Jj i o . filll Punch a Algiers Cairo, - Veracruz, Havannah Cuman 89 oi d 6ff UIGJJ punq "oZZ 89 pu^q O zz OAOqB spireqjuuj CLO CLO * CLINKSTONE. A stone of an imper- fectly slaty structure, which rings like me- tal when struck with a hammer. Its co- lour is gray of various shades; it is brittle; as hard as feldspar, and translucent on the edges. It occurs in columnar and tabular concretions. Sp. gr. 2.57. Fuses easily in- to a nearly colourless glass. Its consti- tuents are 57.25 silica, 25.5 alumina, 2.75 lime, 8.1 soda, 3.25 oxide of iron, 0.25 oxide of manganese, and 3 of water. Klaproth. This stone generally rests on basalt. It occurs in the Ochil and Pent- land hills, the Bass-rock, the islands of Mull, Lamlash, and Islay, in Scotland; the Breidden hills in Montgomeryshire, and in the Devis Mountain, in the county of An- trim. It is found in Upper Lusace and Bo- hemia.* * CLINOMETER. An instrument for measuring the dip of mineral strata. It Was originally invented by R. Griffith, Esq. Professor of Geology to the Dublin Society, and subsequently modified by Mr. Jardine and Lord Webb Seymour. See a descrip- tion and drawing by the latter, in the third volume of the Geological Transactions. Lord Webb's instrument was a very per- fect one. It was made by that unrivalled artist, Mr. Troughton.' * CLOUD. A mass of vapour, more or less opaque, formed and sustained at con- siderable heights in the atmosphere, pro- bably by the joint agencies of heat and electricity. The first successful attempt to arrange the diversified forms of clouds, under a few general modifications, was made by Luke Howard, Esq. We shall give here a brief account of his ingenious classification. The simple modifications are thus named and defined. 1. Cirrus. Parallel, flexu- ous, or diverging fibres, extensible in any or in all directions. 2. Cumulus. Convex or conical heaps, increasing upwards from a horizontal base. 3. Stratus. A widely extended, continuous horizontal sheet, in- creasing from below. The intermediate modifications which require to be noticed are, 4. Cirro-cumulus. Small well-defined roundish masses, in close horizontal arrangement. 5. Cirro- stratus. Horizontal, or slightly inclined masses, attenuated towards a part or the whole of their circumference, bent down- ward, or undulated, separate or in groups, consisting of small clouds having these characters. The compound modifications are, 6. Cu- mulo-stratus. The cirro-stratus, blended with the cumulus, and either appearing in- termixed with the heaps of the latter, or superaddirig a wide-spread structure to its base. 7. Cumulo-cirro-stratus, vel Nimbus. The rain cloud. A cloud or system of clouds from which rain is falling. It is a hori- zontal sheet, above which the cirrus spreads, while the cumulus enters it la- terally and from beneath. The cirrus appears to have the least density, the greatest elevation, the great- est variety of extent and direction, and to appear earliest on serene weather, being indicated by a few threads pencilled on the sky. Before storms they appear lower and denser, and usually in the quarter oppo- site to that from which the storm arises. Steady high winds are also preceded and attended by cirrus streaks, running quite across the sky in the direction they blow in. The cumulus has the densest structure, is formed in the lower atmosphere, and moves along with the current next the earth. A small irregular spot first appears and is as it were the nucleus on which they increase. The lower surface continues ir- regularly plane, while the upper rises into conical or hemispherical heaps; which may afterwards continue long nearly of the same bulk, or rapidly rise into mountains. They will begin, in fair weather, to form some hours after sunrise, arrive at their max- imum in the hottest part of the afternoon, then go on diminishing and totally dis- perse about sunset. Previous to rain, the cumulus increases rapidly, appears lower in the atmosphere, and with its surface full of loose fleeces or protuberances. The formation of large cumuli to leeward in a strong wind, indicates the approach of a calm with rain. When they do not disap- pear or subside about sunset but continue to rise, thunder is to be expected in the night. The stratus has a mean degree of density, and is the lowest of clouds, its in- ferior surface commonly resting on the earth or water. This is properly the cloud of night, appearing about sunset. It com- prehends all those creeping mists which in calm weather ascend in spreading- sheets (like an inundation of water), from the bottom of valleys, and the surfaces of lakes and rivers. On the return of the sun, the level surface of this cloud begins to put on appearance of cumulus, the whole at the same time separating from the ground. The continuity is next destroyed, and the cloud ascends and evaporates, or passes off with the appearance of the nascent cu- mulus. This has long been experienced as a prognostic of fair weather. 1 he cirrus having continued for some time increasing or stationary, usually passes either to the cirro-cumulus or the cirro-stratus, at the same time descending to a lower station in the atmosphere This modification forms a very beautiful sky; is frequent in summer, an attendant on warm and dry weather. The cirro-stratus, when seen in the distance, frequently gives the COA COA idea of shoals of fish. It precedes wind and rain; is seen in the intervals of storms; and sometimes alternates with the cirro- cumulus in the same cloud, when the dif- ferent evolutions form a curious spectacle. A judgment may be formedof the weather likely to ensue by observing' which modifi- cation prevails at last. The solar and lu- nar halos, as well as the parhelion and paraselene, (mock sun and mock moon), prognostics of foul weather, aiv occasioned by this cloud. The cumulo-stratus pre- cedes, and the nimbus accompanies rain. See RAIN. Mr. Howard gives a view of the origin of clouds, which will be found, accompa- nied with many useful remarks, in the I6ih and 17th volumes of the Philos. Magazine.* CI.YSSUS. A word formerly used to de- note the vapour produced by the detona- tion of nitre with any inflammable sub- stance. COAK. Coal is charred in the same man- ner as wood to convert it into charcoal. An oblong- square hearth is prepared by beat- ing the earth to a firm flat surface, and puddling it over with clay. On this, the pieces of coal are piled up, inclining to- ward one another, and those of the lower strata are set up on their acutest angle, so as to touch the ground with the least surface possible. The piles are usually from 30 to 50 inches high, from 9 to 16 feet broad, and contain from 40 to 100 tons of coal. A number of vents are left, reaching from top to bottom, into which the burning fuel is thrown, and they are then immediately closed with small pieces of coal beaten hard in. Tims the kindled fire is forced to creep along the bottom, and when that of all the vents is united, it rises gradually, and bursts out on every side at once. If the coal contain pyrites, the combustion is allowed to continue a considerable time after the disappearance of the smoke, to extricate the sulphur, part of which will be found in flowers on the surface: If it contain none, the fire is cover- ed up soon after the smoke disappears, be- ginning- al thi- bottom, and proceeding gra- dually to the top. In 50, 60, or 70 hours, the fire is in general completely covered "with the ashes of char formerly made, and in 12 or 14 days the coak muv be removed for iiv.". in this way a ton of coals com- monly produces liom 700 to 11.00 pounds of coak. In this way the volatile products of the coal, however, which might be turned to good account, are lost: but some years ago, Lord Lhuvionuhl conceived and car- ried into effect, a plan for saving them. By burning the coal in a range of 18 or 20 stoves, with as little access of air as may be, at the bottom; and conducting the smoke, through proper horizontal tunnels, to a capacious close tunnel 100 yards or more in length, built of brick, supported on brick arches, and covered on the top by a shallow pond of water; the bitumen is condensed in the form of tar: 120 tons of coal yield about 3^ of tar, though some coals are said to be so bituminous as to afford l-8th of their weight. Part of the tar is inspissated into pitch, 21 barrels of which are made of 28 of tar; and the vola- tile parts arising in this process are con- densed into a varnish, used for mixing with colours for out-door pain' ing chiefly. A quantity of ammonia too is collected, and used for making sal ammoniac. The cakes thus made are likewise of superior quaii ty. *COAL. This very important order of combustible minerals, is divided by Pro- fessor Jameson into the following species and sub-species: Species 1. Brown coal, already described. Species 2. Black coal, of which there are four sub-species, slate coal, cannel coal, foliated coal, and coarse coal. 1. Slate coal. Its colour is intermediate between velvet-black, and dark grayish- black. It has sometimes a peacock-tail tarnish. It occurs massive, and in colum- nar and egg-shaped concretions. It has a resinous lustre. Principal fracture slaty; cross fracture, imperfect conchoidal. Hard- er than gypsum, but softer than calcareous spar. Brittle. Sp. gr. 1.26 to 1.38 It burns longer than cannel coal; cakes more or less, and leaves a slag. The constitu- ents of the slate coal of Whitehaven, by Kirwan, are 56.8 carbon, with 43.2 mixture of asphalt and maltha, in which the former predominates. This coal is found in vast quantities at Newcastle; in the coal for- mation which stretches from Bolton, by Al'onby and Workington, to Whitehaven. In Scotland, in the river district of Forth and Clyde; at Cannoby, Sanquhar, and Kir- connel, in Dumfries-shire; in Thuring-ia, Saxony, and many other countries of Ger- manv. It sometimes passes into cannel and foliated coal. 2. Cannel coal. Colour between velvet and grayish-black. Massive Resinous lus- tre. Fracture, flat-conchoidal, or even. Fragments trapezoidal. Hardness as in the preceding sub-species. Brittle. Sp. gr. 1.23 to 1.27. It occurs along with the preceding. It is found near Whitehaven, at Wig An, in Lancashire, Brosely, in Shrop- shire, near Sheffield; in Scotland, at Gil- merton and Muirkirk, where it is called parret coal. It has been wor-'.ed on the lathe into drinking vessels, snuff-boxes, &c. 3. Foliated coal. Its colour is velvet- black, sometimes with iridescent tarnish. Massive, and in lamellar concretions. Re- sinous or splendent lustre; uneven fracture, fragments approaching to trapezoidal. Soft- COA COA er than cannel coal; between brittle and sectile. Easily broken. Sp. gr. 1.34 to 1.4. The Whitehaven variety consists, by Kir- wan, of 57 carbon, 41.3 bitumen; and 1.7 ashes. It occurs in the coal formations of this and other countries. It is distinguish- ed by its lamellar concretions, splendent lustre, and easy frangibility. 4. Coarse coal. Colour dark, grayish- black, inclining to brownish-black. Mas- sive, and in granular concretions. Glisten- ing lustre. Fracture imperfect scaly. Frag- ments indeterminate angular. Hardness as above. Easily frangible Sp. gr. 1.454 It occurs in the German coal formations. To the above, Professor Jameson has ad- ded soot-coal} which has a dark grayish- black colour; is massive; with a dull semi- metallic lustre. Fracture uneven; some- times earthy. Shining streak; soils; is soft, light, and easily frangible. It burns with a bituminous smell, cakes, and leaves a small quantity of ashes. It occurs along with slate-coal in West-Lothian and the Forth district; in Saxony and Silesia. Species 3d. Glance-coal, of which the Professor gives two sub-species, pitch-coal, and glance-coal. 1. Pitch-coal. Colour vel- vet-black. Massive, or in plates and bo- trioidal branches, with a woody texture. Splendent and resinous. Fracture, large perfect conchoidal. Fragments sharp-edged and indeterminate angular; opaque; soft; streak brown coloured. Brittle. Does not soil. Sp. gr. 1.3. It burns with a greenish flame. It occurs along with brown coal in beds, in floetz, trap, and limestone rocks, and in bituminous shale. It is found in the Isles of Sky and Faroe; in Hessia, Bavaria, Bohemia, and Stiria. It is used for fuel, and for making vessels and snufF-boxes. It is called black amber in Prussia, and is cut into rosaries and necklaces. It is dis- tinguished by its splendent lustre and con- choidal fracture. It was formerly called jet, from the river Gaga in Lesser Asia. 2. Glance-coal,- of which we have four kinds, conchoidal, slaty, columnar, and fi- brous. The. conchoidal has an iron -black colour, inclining to brown, with sometimes a tempered steel-varnish. Massive and ve- sicular. Splendent, shining- and imperfect metallic lustre. Fracture flat -conchoidal; fragments sharp-edged. Hardness as above. Brittle, and easily frangible. In thin pieces, it yields a ringing sound. It burns without flame or smell, and leaves awhile coloured ash. Its constituents are S6 r"6 infla-Mma- ble matter, 2 alumina, and 1.38 silica and iron. Jt occurs in beds in clay-slate, gray- wacke, and alum-slate; but it is more abun- dant in secondary rocks, as in coal and trap formations, 'it occurs in beds in the coal formations of Ayrshire, near Cumnock and Kilmarnock; in the coal district of the Forth; and in Staffordshire. It appears to pass into slaty glance-coal. Slaty glance-coal. Colour iron-black. Massive. Lustre shining, and imperfect metallic. Principal fracture slaty; coarse fracture imperfect conchoidal. Fragments trapezoidal. Softer than conchoidal glance- coal. Easily frangible; between sectile and brittle. Sp. gr. 1.50. It burns without flame or odour. It consists, by Dolomieu, of 72.05 carbon, 13.19 silica, 3.29 alumina, 3.47 oxide of iron, and 8 loss. It occurs in. beds or veins in different rocks In Spain, in gneiss; in Switzerland, in mica-slate and clay-slate; in the trap rock of the Calton- hili, Edinburgh; in the coal formations of the Forth district. It is found also in the floetz districts of Westcraigs, in West Lo- thian, Dunfermline, Cumnock, Kilmarnock, and Arran; in Brecknock, Caermarthen- shire, and Pembrokeshire, in England; and at Kilkenny, Ireland; and abundantly in the United States. In this country it is called blind coal. Columnar glance-coal Colour velvet -black and grayish-black. Massive, disseminated, and in prismatic concretions. Lustre glistening, and imperfect metallic. Frac- ture conchoidal. Fragments sharp-edged. Opaque. Brittle. Sp. gr. 1.4. It burns without flame or smoke. It forms a bed several feet thick in the coal-field of San- quhar, in Dumfries-shire; at Saltcoats, in Ayrshire, it occurs in beds and in green- stone; in basaltic columnar rows near Cum- nock, in Ayrshire. Fibrous coal. Colour dark grayish-black. Massive, in thin layers, and in fibrous con- cretions. Lustre glimmering, or pearly. It soils strongly. It is soft, passing into friable. It burns without flame; but some varieties scarcely yield to the most intense heat. It is met with in the different coal- fields of Great Britain. Its fibrous concre- tions and silky hibtre distinguish it from all the other kinds of coal. It is not certain that this mineral is wood mineralized. Several of the varieties may be original carbonaceous matter, crys- tallized in fibrous concretions. Jameson. Parts. Charcoal. Earth. 100 Kilkenny coal contain 97.3 3.7 Anthracite, 90.0 10.0 Ditto, - - 72.0 20.0 Ditto, - - 97.25 2.7 Coal of Notre Dame de Vaux, 78.5 20 The following table exhibits the results of Mr. Mushot's experiments on the. car- bonization and incineration of coals: COA COA Volatile matter Char- coal. Jlshes. Sp. gr. of coal. Sp. gr. of coak. Welsh furnace coal, .... Alfreton do. do. - - - , Butterly do. do. .... Welsh stone do. - - - - Welsh slaty do - - - - * 8.50 45.50 42.83 8.00 9.10 47.00 4.25 16.66 13.00 56.57 13.80 9.10 10.30 33.37 80.00 88.068 52.456 52.882 89.700 84.175 48.362 92.877 69.74 80.475 39.430 82.960 87.491 86.560 54.697 19.500 3.432 2.044 4.288 2.300 6.725 4.638 2.873 13.600 6.525 4.000 3.240 3.409 3.140 11.933 0.500 1.337 1.235 1.264 1.368 1.409 1.278 1.602 1.445 1.436 1.403 1.403 1.150 1. ess than 1. 1.1 1.39 1.657 1.596 1.656 1.622 Derbyshire cannel do. . - - Stone-coal found under basalt, Kilkenny slaty coal, ... Bonlarooneen do. - "^ Corgee coal, - - - V Irish. Queen's County, No. 39. j Stone-wood, Giant's Causeway, It was remarked long ago by Macquer, that nitre detonates with no oily or in- flammable matter, until such matter is reduced to coal, and then only in propor- tion to the carbonaceous matte L it contains. Hence it occurred to Mr. Krrwan, that as coals appear in distillation to be for the most part merely compounds of carbon and bitumen, it should follow, that by the de- composition of nitre, the quantity of car- bon in a given quantity of every species of coal may be discovered, and the pro- portion of bitumen inferred. This cele- brated chemist accordingly projected on a certain portion of nitre in a state of fu- sion, successive 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 entitled to as much confidence as the method permits. Lavoi- sier and Kirwan state, that about 13 parts of dry wood-charcoal decompose 100 of nitre. 100 parts. Charcoal. Bitumen. Earth Sp. ^r. Kilkenny coal, 97.3 3.7 1.526 Comp. cannel, 75.2 21 68 maltha 3.1 1.232 Swansey, 73.53 23.14 mixt. 3.331.357 Leitrim, 71.43 23.37 do. 5.20 1.351 Wigan, 61.73 36.7 do. 1.57 1.268 Newcastle, 58.00 40.0 do. 1.271 Whitehaven 57-0 41.3 1.7 1.257 Slaty -cannel, 47.62 32.52 mal. 20.01.426 Asphalt, 31.0 63.0 bitumen 1.117 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, are chiefly used as fuel in private houses; the caking coals, for smithy forges; the slate coal, from its keeping open, an- swers best for giving great heats in a wind furnace, as in distillation 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 supposed that 3 parts of good Newcas- tle 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 independent coal formation, because the individual depositions of which it is composed, are independent of each other, and are not connected. The second, is that which occurs in the newest floetz- trap formation; and the third occurs in al- luvial land. Werner observes, that a fourth formation mig-ht be added, which would comprehend peat and other similar sub- stances; so that we would have a beautiful and uninterrupted series, from the oldest formation to the peat, which is daily form- ing under the eye. The independent formation contains ex- clusively coarse coal, foliated coal, cannel coal, slate coal, a kind of pitch coal, and slaty glance coal. The latter was first found in this formation in Arran, Dum- fries-shire, Ayrshire, and at Westcraigs, by Professor Jameson. The formation in the newest floetz-trap contains distinct pitch coal, columnar coal, and conchoidal glance coal. The alluvial formation con- tains 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 sandstone, which is always mica- ceous; and lastly, slate -clay. But besides these, there occur also beds of harder sand- COA COA stone, marl, limestone, porphyritic stone, which the arts of life have ever derived bituminous shale, clay -ironstone; and as dis- from philosophical research and sagacity, covered by Professor Jameson, greenstone, j n the year 1798, Mr. Murdoch, after se amygdaloid, and graphite. The slate-clay is well characterized, by the great variety of vegetable impressions of such plants as veral trials on a small scale five years be- fore, constructed at the Foundry of Messrs. Bolton and Watt, an apparatus upon a large flourish in marshes and woods. The scale, which during many successive nights smaller plants and reeds occur in casts or was applied to the lighting of their prin- impressions always laid in the direction of cipal building; and various new methods the strata; but the larger arborescent plants wer e 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 kingdom, was partly lighted by gas under Mr Murdoch's di- often stand erect, and their stems are fil- led with the substance of the superincum- bent strata, which seems to show that these stems are in their original position. The leaves and stems resemble those of palms rection; and the light was soon extended and ferns. The central, northern and over the whole manufactory. In the same western coal mines of England; the river year, I lighted up the large lecture-room coal districts of the Forth and the Clyde, o f Anderson's Institution with coal-gas, and the Ayrshire, and in part the Dum- generated in the laboratory; and continued 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 gene- ral form of our great independent coal- beds, is semi-circular, or semi-elliptical, being the segment of a great basin. The strata have a dip or declination to the horizon of from 1 in 5, to 1 in 20. They are rarely vertical, and seldom perfectly 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 volatilized in the state of conden- sible tar. Little gas, and that of inferior illuminating power, is produced. This dis- tillatory temperature may be estimated at about 600 to 700 F. If the retort be horizontal to any considerable extent. pre viously brought to a bright cherry-red Slips and dislocations of the strata, how- heat) then tlle coa l s ,the instant after their supply ever, derange more or less the general form of the basin. Those who wish to understand the most improved modes of working coal mines, introduction, yield a copious supply of good gas, and a moderate quantity of tarry and ammoniacal vapour. But when the re- tort is heated vo nearly a white incandes- will be amply gratified by consulting, A cence} tne part of the gas richest in light, J?//i/i9*y* />7 tht> J .piTiQtpY* f^.nnl T\i&tv*irt Tiv * i -A 1 X*~...;~ . ..-, I'. + .r Report on the Leinster Coal District, by Richard Griffith, Esq. Professor of Ge- ology, and Mining Engineer to the Dublin Society. The author has given a most lu- minous view of Mr. Buddie's ingenious is attenuated into one of inferior quality, as I have shown in detailing Berthollet's experiments on CARBURETTED HYDRO- GEN. A pound of good cannel coal, pro- perly treated in a small apparatus, will system of working and ventilating, in which yie i c [ fi ve cu iji c f eet O f ffa s, equivalent in f 0 18 . 5 15<62 Deutox [ Cobalt 5A Deutox. [oxygen, 2.0 100.00 100 73 37 27 100 The precipitated oxide of cobalt, wash- ed 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; sul- phuretted hydrogen produces no precipi- tate, but hydrosulphurets throw down a black powder, soluble in excess of the pre- cipitant; tincture of galls gives a yellow- ish-white precipitate; oxalic acid throws down the red oxalate. Zinc does not pre- cipitate this metal. The sulphate is formed by boiling sul- phuric acid on the metal, or by dissolving the oxide in the acid. By evaporation, the salt may be obtained in acicular rhomboi- dal prisms of a reddish colour. These are insoluble in alcohol, but soluble in 24 parts of water. It consists, by the analy- sis 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 Dr. Thomson's hypothetical synthesis differs widely from the experimental, in consequence of his assuming 3.625 for an atom of the metal, and 4.625 for that of its oxide. He gives 28.57 acid + 26.43 pro- toxide -f- 45 water. The nitrate forms prismatic red deliques- cent crystals. It is decomposable by gen- tle ignition. The muriate is easily formed by dissolving the oxide in muriatic acid. The neutral solution is blue when concen- trated, and red when diluted; but a slight excess of acid makes it green. According to Klaproth, a solution of the pure muriate forms a sympathetic ink, whose traces be- come blue when the paper is heated; but if the salt be contaminated with iron, the traces become green. I find that the addi- tion of a little nitrate of copper to the so- lution 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 re- moval 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 disappearance, to the re ab- sorption of moisture. At a red heat, the greater part of the muriate sublimes in a gray coloured chloride. The acetate forms a sympathetic ink, whose traces be- ing 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 o COG COF cobalt may be obtained in large rhomboi- dal crystals, by adding- the tart rate of pot- ash to cobaltic solutions, and slow evapo- ration. An ammonia-nitrate of cobalt may be formed in red cubical crystals, by add- ing- ammonia in excess to the nitric solu- tion, and evaporating at a very gentle h.-at. They have a urinous taste, and are perma- nent in the air. The red oxalate is soluble in an excess of oxalic acid, and hence neu- tral oxalate of potash is the proper reagent for precipitating cobalt. The phosphate may be formed by double decomposition. It is an insoluble purple powder, which, heated along with eight parts of gelatinous alumina, produces a beautiful blue pig- ment, a substitute for ultra-marine. The colouring power of oxide of cobalt on vitri- tiable mixtures, is greater perhaps than that of any other metal. One grain gives a full blue to 240 grains of glass. Zafire is a mixture of flint powder and an impure oxide of cobalt, prepared by calcination of the ores. Smalt and azure blue are mere- ly cobaltic glass in fine powder. See GLASS.* * COBALUS. The demon of mines, which obstructed and destroyed the miners. The church service of Germany formerly con- tained a form of prayer for the expulsion of the fiend. The ores of the preceding metal being at first mysterious and in- tractable, were nicknamed cobalt.* * COCCOLITE. A mineral of green co- lour of various shades, which occurs, mas- sive; in loosely aggregated concretions; and crystallized in six-sided prtsms, with two opposite acute lateral edges, and bevelled on the extremities, with the bevelled planes set on the acute lateral edges; or in four-sided prisms. The crystals are gene- rally rounded on the angles and edges. The internal lustre is vitreous. Cleavage, double oblique angular. Fracture uneven. Translucent on the edges. It scratches apatite, but not feldspar. Is brittle. Sp. gr. 3.3. It fuses with difficulty before the blow- pipe. Its constituents are silica 50, lime 24, magnesia 10, alumina 1.5, oxide of iron 7, oxide of manganese 3, loss 4.5. Vauquclin. It occurs along with granular limestone, garnet and magnetic ironstone, in beds subordinate to the trap formation. It is found at Arendal in Norway, Nericke in Sweden, Barkas in Findland, the Hartz, Lower Saxony, and Spain.* 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 gray colour inclining to purple. The gray is owing to a powder which covers it na- turally, a part of which it still retains: the purple tinge proceeds from the colour ex- tracted by the water in which it has been killed. Cochineal will keep a long time in a dry place. Hellot says, that he tried some, one hundred and thirty years old, and found it produced the same effect a 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 ani- mal matter, a fat like common fat, and with different salts. The fat having been separated by ether, and the residuum treated with boiling alcohol, they allowed the alcohol to cool as they gently evapora- ted 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 mat- ter untouched, and by mixing the solution with ether, and thus precipitating the co- louring matter in a state of great purity, which they have called car minium. It melts at 122 F*ahr. becomes puffy, and is de- composed, but does not yield ammonia. It is very soluble in water, slightly in alcohol, and not at all in ether, unless by the in- termediation of fat. Acids change it from crimson, first to bright red, and then to yellow; alkalis, and, generally speaking, all protoxides turn it to violet; alumina takes it from water. Lake is composed of car- minium and alumina. Carmine is a triple compound of an animal matter, carminhim, 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 co/ea ara- bica are contained in an oval kernel, enclo- sed 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 adhering mem- branes by winnowing. Besides the pecu- liar bitter principle, which we have de- scribed under the name caffbin, coffee con- tains several other vegetable products. According to Cadet, 64 parts of raw coffee COH COH consist of 8 gum, 1 resin, 1 extractive and bitter principle, 3.5 gallic acid, 0.14 albu- men, 43.5 fibrous insoluble matter, and 6.86 loss. Hermann found in 1920 grains of Levant Coffee. Mart. Coffee. Resin, 74 68 Extractive, 320 310. Gum, 130 Fibrous matter, 1335 1386 Loss, 61 12 1920 1920 Craigleith stone, The nature of the volatile fragrant prin- ciple, developed in coffee by roasting, has not been ascertained. The Dutch in Su- rinam improve the flavour of their coffee by suspending bags of it, for two years, in a dry atmosphere. They never use new coffee.* Coffee is diuretic, sedative, and a cor- rector of opium. It should be given as medicine in a strong infusion, and is best cold. In spasmodic asthma it has been par- ticularly serviceable; and it has been re- commended in gangTfne of the extremities arising from hard drinking. * COHESION, or attraction of cohesion, is that power by which the particles of bo- dies are held together. The absolute co- hesion of solids is measured by the force necessary to pull them asunder. Heat is excited "at the same lime. At the iron cable manufactory of Captain Brown, a cylindrical bar of iron, 14 inch diameter, was drawn asunder by a force of 43 tons. Before the rupture, the bar lengthened jtbout 5 inches, and the section of fracture was reduced nearly -| of an inch. About this part, a degree of heat was generated, which, according to Mr. Barlow of Wool- wich, rendered it unpleasant, if not in a slight degree painful, to grasp the 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, calcu- lated 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 elaborate tables of cohesion drawn up by Mr. Thomas Tredgold, and published in the 50th vol. of Tilloch's Magazine, the specific cohe- sion of plate glass (a pretty uniform body) c ast iron, is denoted by unity. Cast copper, The following table is the result of ex- Fine yellow brass, periments by George Rennie, .Fun. Esq. Wrought copper, published in the first part of the Phil. Cast tin, Transactions for 1818. Cast lead, Mr. Rennie found a cubical inch of the following bodies crushed by the following- weights: Ibs. ov. Elm, American pine, ... 1606 White deal, .... 1928 English oak, .... Ditto of five inches long, slipped with, 2572 Ditto of four inches, ditto, - 5147 A prism of Portland stone, two inches long, Ditto statuary marble, 3216 8688 Cubes of l 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 quar- ry, - - 2.428 9776 Kilialy white freestone, not stratified, - - - 2.42,1 10264 Portland, - - - 2.428 10284 Craigleith, white freestone, 2.452 12346 Yorkshire paving, with the strata, - - - 2.507 12856 Ditto, against the strata, 2.507 12856 White 'statuary marble, not veined, *- - - 2.760 13632 Bramley-Fall sandstone, near Leeds, with strata, - 2.506 13632 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 Craigleith, with strata, 2.452 15560 Devonshire red marble, varie- gated, 16712 Compact limestone, - 2.584 17354 Peterhead granite, hard close- grained, Black compact limestone, Li- merick, - 2.598 19924 Purbeck, - 2.599 20610 Black Brabant marble, 2.697 20742 Very hard freestone, White Italian veined marble, 2.726 21 783 Aberdeen granite, blue kind, 2.625 24556 Cubes of different metals of th inch were crushed by the following weights. 9773 7318 - - 10304 6440 966 COL COL 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, - - 1166 Di to, vertical, - - - 1218 CjiSt steel, previously tilted, - 8o91 Blistered steel, reduced by the ham- mer, 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 ham- mer, 2112 Cast copper, .... 1192 Fine yellow brass, - - . 1123 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 S'rckingen with those made at Woolwich, of which an ac- count was given in the Annals of Philosophy, vii. 320. From that comparison, the propor- tional strengths were as follows: English iron, Swedish iron, 348.38 549.25 But from Mr. Rennie's experiments, the pro- portional strengths are: English iron, Swedish iron, 348.38 449.34 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 inch of zinc breaks with 26 pounds. Mechenbroek. Do. Do. Do. Do. Do. Do. Do. lead tin copper brass silver iron gold A cylinder 1 inch iron According to Sickingeu, the relative co- hesive strengths of the metals are as fol- lows: Gold, Silver, Platina, Copper, Soft iron, Hard iron, 150955 190771 262361 304696 362927 559880 A wire of iron 0.078 or j~ of an inch, will just support 549.25 pounds. Emerson's number for gold is excessively incorrect. In general, iron is about 4 times stronger than oak, and 6 times stronger than deal.* * COHOBATION The continuous redistil- lation of the same liquid, from the same ma- terials.* 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 eall it crocus, or crocus martis. COLD. The privation of heat. See C Ato- nic, CONGELATION, and TEMPERATURE. COLOPHONY. Colophony, or black resin, is the resinous residuum after the distilla- tion of the light oil, and thick dark reddish balsam, from turpentine. 49* 299J 360 370 450 500 63320 Emerson. do. do. do. do. do. do. Rumford. *CoLUMBruM. If the oxide of columbium 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 gray colour; and when newly abraded, the lustre nearly of iron. Its sp. gr., when in agglutinated particles, was found by Dr. Wollaston to be 5.61. These metallic grains scratch glass, and are easy pulverized. Neither nitric, mu- riatic, 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.)* *COLCHICUM ArTUMNALE. A medicinal plant, the vinous infusion of whose root has been shown by Sir E. Home to possess spe- cific powers of alleviating gout, similar to those of the empirical preparation called Eau medicinale D'Husson. The sediment of the infusion ought to be removed by filtra- tion, as it occasions gripes, sickness, and vomiting.* * COLOFHONITE. A mineral of a blackish, or yellowish -brown, or orange -red colour; of a resino-adamantine lustre; and conchoi- dal 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 40 COM COM in rhomboidal dodecahedrons, whose sur- faces 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.* * 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 tempera- ture is necessary, which differs for every dif- ferent combustible. This difference thrown into a tabular form, would constitute their scale of accendibility, or degree of accension. Stahl adopted, and refined on the vulgar belief of the heat and light com.ng from the combustible itself; Lavoisier advanced the opposite and more limited doctrine, that the heat and light proceeded from the oxy- genous gas, in air and other bodies, which lie regarded as the true pabulum of fire. Stahl's opinion is perhaps more just than Lavoisier's; f-r man} combustibles burn to- getlivr, without the presence of oxygen or of any analogous fancied supporters; us chlorine, and the adjuncts to oxvgen, have bten iMiphilosophically called. Sulphur, hy- dros.;; n, carbon, and azote, are as much entitled to be styled supporters, as oxygen and chlorine; for potassium burns vividly in sulphuretted hydrogen, and in pruss'me, and most of the metals burn with sulphur alone. lit at 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 regard- ing oxygen, chlorine, and iodine, to be in reality combustible bodies; perhaps more so, than those substances vulgarly called com- bustibie. Experiments with the condensing syringe, and the phenomena of the decom- pusiuon of euchlorine, prove that light as well as heat, tuuy 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 desig- nation, as much as charcoal and sulphur. Azote is declared by the expounders of the Lavcusierian creed, to be a simple incombus- tible. Ytt its mechanical condensation proves that it can afford, from its own resources, an incandescent hea ; and with chlorine, iodine, and metallic oxides, all incombustibles on the antiphlogistic notion, it forms com- pounds 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, some- times sufficiently incredulous on subjects of rational belief. See the next article. The electric polarities unquestionably show, what no person can wish to deny, that be- tween oxygen, chlorine, iodine, on one hand, and hydrogen, charcoal, sulphur, phospho- rus, 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 definitive 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 sul- phur should be ranked along with oxygen, chlorine, and acids, apart from combusti- bles, whose polarities are negative. Sul- phuretted hydrogen in its electrical relations to metals, ranks also with oxygen and acids. How vague and fallacious a rule of classifi- cation electrical polarity would afford, may be judged of from the following unquestion- able 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, sulphur and the metals, the acid and alkaline substances, afford opposite 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 zine, water, and diluted nitric acid, the sur- face exposed to the acid is negative; 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 sc'ine chemical agencies of electricity by Sir H. Davy, Phil. Trims. 1807. Combustibles have been arranged into sin pie and compound. The former consist cf hydrogen, carbon, boron, sulphur, phos- phorus, and nitrogt n, besides all the metals. The kuter class comprehends the hydrurets, carburets, sulphurets, phosphurets, metallic alloys, and organic products.* *COMBISTION. The disengagement of heat and light which accompanies chemical combination. It is frequently made to be synonymous with inflammation, a term which might' be restricted, however, to that peou- liar species of combustion, in which gaseous matter is burned. Ignition is the incandes- cence of a body, produced by extrinsic means, without change of its chemical con- stitution. Beccher and Stahl, feeling daily the neces- sity of tire to human existence, COM COM ed with the metamoiyhoses which this power seemed to cause charcoal, sulphur, and me- tals to undergo, came to regard combustion as the single phenomenon r the general the- ory of chemical action, that the quantity of heat developed at the instant of the combi- nation of bodies, has no relation to the ca- pacity of the elements, and that in the greatest number of cases, this loss of heat is not followed by any diminution in the ca- pacity of the compounds formed. Thus, for example, the combination of oxygen and hydrogen, or of sulphur and lead, which" produces so great a quantity of heat, occasions no greater alteration in the capa- city of water, or of sulphuret of lead, than the combination of oxygen with copper, lead, silver, or of sulphur with carbon, pro- duces in the capacities of the oxides of these metals, or of carburet of sulphur." " We conceive that the relations which we have pointed out between the specific heats of simple bodies, and of those of their com- pounds, prevent the possibility of suppos- ing, that the heat developed in chemical actions, owes its origin merely to the heat produced by change of state, or to that sup- posed to be combined with the material molecules;" Jlnnaks deChimie et Physique, x. Mr. Dalton, in treating ot 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 usu- ally referred to the condensation of volume. The following examples will show the falla- cy of such crude hypotheses. 1. Chlorine and hydrogen mixed, explode by the sun- beam, electric spark, or inflamed taper with the disengagement of much heat and light; and the volume of the mixture, which is greatly enlarged at the instant of combination, suffers no condensation afterwards. Muri- atic acid gas, having the mean densily of its components, is produced. 2- When one voiume of olefiant gas and one of oxygen are detonated together, three and a halt ga- seous volumes result, the greater part of the hydrogen remains untouched, and a volume and a half of carbonic oxide is formed, with about 1-lOth 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 1.3J2, was mixed with water in the proportion of 44.05. to 33.76. The tempe- rature of the mixture sank. 8.9; but the density at 61 was 1159, while the mean density was only 1.-51. 2. On adding wa- ter to the preceding mixture, in the pro- portion of 33.64 to 39 28, the temperature sank 3 4, while the density continued 000.3 above the mean. Other saline solutions pre- sented the same result, though none to so great a degree. That the internal motions which accom- pany the change in the mode of combination, independent of 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 examining the combinations of antimony, he discovered, accidentally, that several me- talline antimoniutes, when they begin to grow red-hot, exhibit a sudden appearance of fire, and then the temperature again sinks to that of the surrounding combusti- bles. He made numerous experiments to elucidate the nature of this appearance, and ascertained that the weight of the salt was not altered, and that the appearance to-;k place without the presence of oxygen. Be- fore the appearance of fire, these salts are very easily decomposed, but afterwards 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 appearances 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 precipitat- ed by hydro-suiphuret of potash, and the precipitate 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 hydro-- gen gas, while a combustion similar to that in the formation of the metallic sulphurets appeared, and common sulphuret of plati- num remained behind. When we heat the oxide of rhodium, obtained from the soda- muriate, water first comes over; and on in- creasing 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 euc/ilorine of Sir il. Davy. Gadolinite, the sihcuite of > ttria, was first observed by Dr. Wolluston COM COM to display 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 tht blow- pipe, so that the whole piece becomes equal- ly hot. At a red-heat it catches fire. The colour becomes greenish-gray, and the so- lubility in acids is destroyed. Two small pieces of gadolinite, one of which liad 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. Fi- nally, Sir H. Davy observed a similar phe- nomenon on heating hydrate of zirconia. The verbal hypothesis of thermoxygen by Brugnatelli, with Dr. Thomson's supporters, partial supporters, andsemicombustion, need not detain us a moment from the substantial tacts, the noble truths, first revealed by Sir H Davy, concerning the mysterious process of combustion. Of the researches winch brought them to light, it has been said, with- out any hyperbole, that " it Bacon were to revisit the earth, this is exactly such a case as we should chuse to place before him, in order to give him, in a small compass, an idea of the advancement which philosophy has made since the time, when he had point- ed out to her the route which she ought to pursue." The coal mines of England, alike essen- tial to the comfort of her population and her financial resources, had become infested with fire-damp, or inflammable air, to such a de- gree as to render the mutilation and destruc- tion of the miners, by frequent and tremen- dous explosions, subjects ot sympathy and dis- may te the whole nation. By a late explo- sion in one of the Newcastle collieries, no less than one hundred and one persons per- ished 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 assigned to himself; and which, had his genius been baffled, the king- dom could scarcely hope to see achieved by another. But the stubborn forces of nature can only be conquered, as Lord Bacon just- ly pointed out, by examining them in the nascent state, and subjecting them to expe- rimental interrogation, under every diver- sity of circumstance and form. It was this in* c sligation, which first laid open the hi- therto unseen and inaccessible sanctuary of Fire. As some invidious 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 pre- face the account of them by the following extract from "Resolution of a Meeting held for considering the facts relating to the Dis- covery of the Lamp of Safety." Soho Square, JVbu. 20, 1817. ,3d That Sir H. Davy net only disco- vered, independently of all ethers, and with- out any knowledge ot the unpublished expe- riments of the late Mr. Tennant on Flame, the principle of the non-communication of explosions through SJT all apertures, but that he has also the sole rn^rit of having first ap- plied it to the very important purpose of a safeiy-lamp, which has evidently been imi- tated in the latest lamps of Mr. George Ste- phenson. (Signed) Joseph Banks, P. R. S. William .1. Brande, Charles Hatchett, William Hyde Wollaston, Thomas Young." See the whole document in Tilloch's Maga- zine, vol. 50. p. 387. The phenomena of combustion may be conveniently considered under six Heads: 1st. The temnerature necessary to inflame different bodies. '2d, The nature of flame, and the relation between the light and heat which compose 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 Infe- rences. 1st Of the temperature necessary to inflame different bodies. 1st. A simple experiment shows the successive combustibilities of 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 light- ed taper. It will be extinguished, before it reaches the bottom of the neck. Then in- troduce a small tube, containing zinc and dilute sulphuric acid, at the aperture of which the hydrogen is inflamed. The hy- drogen will be found to burn in whatever part of the bottle the tube is placed. After the hydrogen is extinguished, introduce lighted sulphur. This will burn for some time; and after its extinction phosphorus will be as luminous as in the air, and, if heated in the bottle, will produce a pale yellow flame of considerable density. Phosphorus is said to take fire when heat- ed to 150 and sulphur to 550. Hydrogen inflames with chlorine at a lower tempera- ture 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 com- bine rapidly with a species of silent com- bustion. A mixture of common air and hy- drogen was introduced into a small copper tube, having a stopper not quite tight; the copper tube was placed in a charcoal fire; before it became visibly red-hot an explo- sion took place, and the stopper was driven out. We see, therefore, that the inflaming temperature is independent of compression or rarefaction. COM COM The ratio of the combustibility of the dif- ferent gaseous matters, is likewise to a cer- tain extent, as the masses of heated matters required to inflame them. Thus, an iron wire l-40th of an inch, heated cherry-red, will not inflame oleh'ant gas, but it will in- flame hydrogen gas. A wire of l-8th, heat- ed to the same degree, will inflame oleh'ant g-as. But a wire -i- of an inch, must be Tic at- ed to whiteness to inflame hydrogen, though at a low red-heat it will inflame bi-phosphu- retted gas. Yet wire of 1 -40th, heated even to whiteness, will not inflame mixtures of h're-damp. Carbonic oxide inflames in the atmosphere when brought into contact with an iron wire heated to dull redness; whereas carburetted hydrogen is not inflammable, un- less the iron i's heated to whiteness, so as to burn with sparks. These circumstances will explain, why a mesh of wire, so much finer or smaller, is required to prevent the explosion from hy- drogen and oxygen, from passing; and why o course a texture and wire are suflicient to prevent the explosion of the fire-damp, fortunately the least combustible of all the Inflammable gases known. The flame of sul- phur, which kindles at so low a temperature, will exist under refrigerating proc< sst s, 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 sur- face 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 1 -10th of an inch diameter, be brought over the flame. Though ut 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 be- ing extinguished. That f he effect depends entirely on the pov er of the metal to ab- stract the heat of flame, is shown by bring- ing a glass capillary ring* of the same diame- ter and size over the flame. This being a much worse conductor of heat, will not, even when cold, extinguish it. If its size, how- ever, be made greater, and its circumference smaller, it will act like the metallic wire, and require to be heated to prevent it from ex- tinguishing the flame. Now, a flame of sul- phur 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, diminish- es but slight ly the size of a flame of sulphur, of the same dimensions. By the following simple contrivance, we may determine the relative facility of burn- ing, among- different combustibles. Prepare a series of metallic globules o! 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 -20th of an inch diameter be brought near an oil flame of 1-3 Jth 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 particular flame, will be a measure of its combustibility. If the glo- bule be heated, however, the distance will diminish at which it produces extinction. At a white heat, the globule, in the above in- stance, does not extinguish it by actual con- tact, though at a dull red-heat it immediately produces the effect. 2d Of the nature of fame, and of the rela- tion between the light mid the. heat which cwn- P'ise it. The flume of combustible bodies may in all cases be considered, as the com- bustion of an explosive mixture of inflammable gus, or vapour, with air. It cannot be re- garded as a mere combustion, at the surface of contact, of the inflammable matter. Tin's fact is proved by holding a taper, or a piece of burning phosphorus, within a large flame made by the combustion of alcohol. The flame of the taper, or of the phosphorus, will appear in the centre of the other flame, proving that there is oxygen even in its in- terior 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 cur- rent 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 combustion of explosive mixtures, under different circumstances, should produce such different appearances?" In reflecting on the circumstances of these two species of com- bustion, 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 w-as in the smallest quantity, 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 experiments show, 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 he- fore it inflames, the light becomes feebler, and at a certain distance the flame assumes the precise character of that of an explo- sive mixture burning within the lamp. But though the light is so feeble in this case, tfce COM COM be at is greater than when the Fight is much more vivid. A piece of wire of platina, held in this feeble blue flame, becomes instantly white-hot. On reversing the experiment by inflaming a stream of coal-gas, and passing a piece of wire gauze gradually from th summit of the flame to the orifice of the pipe, the re- sult is still more instructive. It is found that the apex of the flame, intercepted by the wire-gauze, affords no solid charcoal; but in passing it downwards, solid charcoal is given off in considerable quantities, and prevented from burning by the cooling agen- cy of the wire-gauze. At die bottom of the flame, where the gas burned blue, in its immediate contact with the atmosphere, char- coal ceased to be deposited in visible quan- tities. The principle of the increase of the brilli- ancy and density of flame, by the production and ignition of solid matter, appears to ad- mit of many applications. Thus, olefiant gas gives the most brilliant white light of all combustible gases, because, as we learn from Bei thollet's experiments, related under carburetted hydrogen, at a very high tem- perature, it deposites a very large quantity of solid carbon- Phosphorus, which rises in vapour at common temperatures, and the vapour of which combines 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, however, exist in a given space, that they scarcely raise the tem- perature of a solid body exposed to them, though, as in the rapid combustion of phos phorus, where immense numbers are exist- ing 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 blow-pipe. 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 deposition. It explains also the intensity of the light of those fames in which Jixed 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 feeble- ness of the light of those flames in which gaseous and volatile matter alone is pro- duced, such as those of hydrogen and of sul- phur 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, or by placing in them very fine amianthus or metallic gauze. It leads to deductions concerning the chemic 1 nature of bodies, and various phe- nomena of their decomposition. Thus ether burns with a flame, which seems to indicate the presence of olefiant gas in that substance. Alcohol burns with a flame similar to that of a mixture of carbonic oxide and hydro- gen. Hence the first is probably a binary compound of olefiant gas and water, and the second of carbonic oxide and hydrogen. When protochloride 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 copper 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 colour of flame is changed by the intro* duction of incombustible compounds, that the effect depends on the production, and subsequent ignition or combustion of in- flammable matter from them. Thus the rose-coloured light given to flame by the compounds of strontium and calcium, and the yellow colour given by those of barium, and the green by those of boron, may de- pend upon a temporary production of these bases, by the inflammable matter of the flame , Dr. Clarke's experiments on the reduction of barytes, by the hydroxygen lamp, is fa vourable to this idea, ftor should any sup- posed inadequacy of heat in ordinary flame, prevent us from adopting this conclusion. Flame, or gaseous matter heated so highly as to be luminous, possesses 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 experi- ment. Hold a fine wire of plantinum about l-2Gth of an inch from the exterior of the middle of the flame of a spirit-lamp, and conceal the flame by an opaque body. The wire will become white -hot in a space, where there is no visible light. The real tem- perature of visible flame is perhaps as high as any we are acquainted with. Mr. Ten- nant used to illustrate this position, by fusing a small filament of platinum, in the flame of a common candle. These views will probably offer illustra tions of electrical light. The voltaic arc of flame from the great battery, differs in co lour and intensity, according to the substan- ces employed in the circuit, and is infinitely more brilliant and dense with charcoal than with any other substance. May not this de- pend, says Sir H. Davy, upon particles of the substances separated by the electrical attractions? And the particles of charcoal, being the lightest among solid bodies (as COM COM their prime 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 mixture of oxygen and hydrogen compressed in Newman's blow-pipe apparatus. (Si-e BLOW-PIPE). This flame is hardly visible in bright day-light, yet it instantly fuses the most refractory bodies; and the light from solid bodies ignited in it, is so vivid as to be painful to the eye. This application cer- tainly originated from Sir H. Davy's dis- covery, that the explosion from oxygen and hydrogen would not communicate through very small apertures, and he himself first' tried the experiment with a fine glass capil- lary 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. 3. Of the heat disengaged by different com- bustibles in the act of burning. Lavoisier, Crawford, Dalton, and Rum- ford, in succession, made experiments to de- termine the quantity of heat evolved in the combustion of various bodies. The appa- ratus 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 temperature im- parted. The following is a general table of results: Substances burned, 1 Ib. Oxygen consumed inlbs. Ice melted in Ibs. Lavoisier. Crawford Dalton. Ruraford. Hydrogen, 7.5 <^J.O 48U 3^0 Car! >ure tted hydrogen, Olefiant gas, 4 3.50 85 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 12624 Tallow, 3.0 96 104 111.58 Oil of turpentine, 60 Alcohol, - 2.0? 58 67.47 E-..'u-r sulphuric, 3 62 107.03 Naphtha, - 97.83 Phosphorus, Charcoal, 1.33 2.66 100 96.5 69 60 40 Sulphur, 1.00 20 Camphur, 70 Caoutchouc, 42 The discrepancies in the preceding table, are sufficient to show the necessity of new experiments on the subject. Count Rum- ford made a series of experiments on the heat given out during the combustion of dif- ferent 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 carbon; 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 burning one of wood. In treating of acetic acid and carbon, I have already taken occasion to state, that they appear greatly to overrate the propor. tion 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 propor- tions of oxygen consumed by olive oil, phos- phorus, charcoal, and sulphur, are all in like manner erroneous. In vol. i p. 184. of Dr. Black's lectures, we have the following 1 notes. " 100 pounds weight of the best Newcastle coal, when applied by the most judiciously constructed furnace, will convert about i 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 51 COM COM times as much heat to convert the boiling water into steam. Therefore, 3 ~ =- 6|-, is the weight of water that would be converted into steam by one pound of coal. Mr. Watt found, that it requires 8 feet surface of boiler to be exposed to fire to boil oft' one cubic foot of water per hour, and lhat a bushel, or 84 pounds of Newcastle coal so applied, will boil off from 8 to 12 cu- bic feet. He rated the heat expended in boil- ing off a cubic foot of water, to be about six times as much as would bring 1 it to a boiling- heat from the medium temperature (5.5), in this climate. The mean quantity is 10 cu- bic feet, which weigh 625 pounds. Hence 1 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 Kewcastle coal. The cubical coal of the Glasgow coal district, is reckoned to have only | the calorific power of the Newcastle oal; 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. 1 shall now describe the experiments re- cently made on this subject by Sir H. Davy, subservient 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 filled with olive oil, in which a thermo- meter was placed. The oil was heated to 212, to prevent any difference in the com- munication of heat, by the condensation of aqueous vapour; the pressure was the same for the different gases, and they were con- sumed 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: Substances-. Rise of therm. Osyj^en "Ratios of from 212 to consumed* heat. Olefiantgas, 270 6.0 9.66 Hydrogen, 238 1.0 26.0 Sulph. hydrogen, 232 3.0 6.66 Coal gas, . 236 4.0 6,00 Carbonic oxide, 218 1.0 6.00 The data on which Sir H. calculates the ratios of heat, are the elevations of tempera- ture, and the quantities of oxygen consumed conjointly. We see that hydrogen produces more heat in combustion than any of its com- pounds, a fact accordant with Mr. Dalton's results HI 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 thts point, howcvcn-, Sir W. VOJ.. ! with his usual sagacity remarks, that it wili be useless to reason upon the ratios as exact, for charcoal was deposited from both the olefiant gas and coat gas during the experi- ment, and much sulphur was deposited from the sulphuretted hydrogen. It confirms, 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 a 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 rare- faction necessary for this effect has been differently stated. On this point, Sir H. Da- vy's investigations are peculiarly beautiful and instructive. When hydrogen gas, slow- ly produced from a proper mixture, was in- flamed at a fine orifice of a glass tube, as in Priestley's philosophical candle, so as to make a jet of flame of about l-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 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 burn- ed above, till its pressure was between 7 and 8 times less: when it became extin- guish ed To ascertain whether the effect depended upon the deficiency of oxygen, he used a larger jet with the same apparatus, when the flame 10 his surprise, burned longer; even when the atmosphere was rarefied 10 times; and this in repeated trials. When the larger and this isin repeated trials. \Vhenthelarger jet came white-hot, and continued red-hot till the flame was extinguished. It immediately occurred to him, that the heat communicat- ed 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 confirmed the conclusion. A piece of v;ire of plati- num was coiled round the top of the tube, so-asto reach into and above the flame. The jet of gas of l-6th of an inch in height WHS 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 contin- ued 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 WOT d'lfl red, the gas, though certainly ex 41 COM COM ting-dished below, continued to bum in con- tact with the hot wire, and the combustion did not cease, until the pressure was re- duced 13 times It appears from this result, that the flame of hydrogen is extinguished in rarefied at- mospheres, only when the heat it produces is insufficient to keep up the combustion: which appears to be when it is incapsftle of communicating visible ignition to metal; and as this is the temperature required for the inflammation of hydrogen, (see section 1st,) at common pressure, it appears that its com- bustibility is neither diminished nor increased by rarefactidn from the removal of pressure. Arc-Tcling to this view, with respect to hydrogen, it should follow, that those a- mo)i ( yst other combustible bodies, which re- quire less heat for their accension, ought to burn in more rarefied air than those that re- quirt 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 j(eat. Every experiment since nude, con- . iis these conclusions. Thus olofumt gas, i-.ich approaches nearly to hydrogt n, in the . inerature produced by its combust'on, vhich 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 plantinum, 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 thr wax taper, which require a greater con- sumption of caloric for the volatili zation and decomposition of their combustible matter, were extinguished when the pressure was 5 or 6 times less without the wire of platinum, a;,d 7 or 8 times less when the wire was kept in the flame. Light carburetted hydro- gen, which produces, as we have seen, less heat in combustion than any of the common coinbusuble gases, except carbonic oxide, and which requires a higher temperature for its sicceusion than any other, has its flame extinguished, even though the tube was fur- nished with the wire when the pressure was below l-4th. Tin- flame of carbonic oxide, which though it produces little heat in combustion, is as ace' ndible 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 decomposi- tion during its combustion in rare air, when burned in the same apparatus as the defiant and orher gases, was extinguished when the pressure was l-7th. Sulphur, which requires a lower tempera- ture for its accension, than any common in- ibie 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 plantinum to dull red- ness; nor was it extinguished till the pres- sure was reduced to l-20th. From the pre- ceding experimental facts we may infer, that the taper would be extinguished at a height of between 9 and 10 miles, hydrogen be- tween 12 and 13; and sulphur between 15 and 16. Phosphorus, as has been shown by M. Van Marum, burns in an atmosphere rare- fied 60 times. Sir H. Davy found, that phosphuretted hydrogen produced a flash of light when admitted into the best vacuum that could be made, by an excellent pump pf Nairn's construction. Chlorine and hydrogen inflame at a much lower temperature, than oxygen and hydro- gen. Hence the former mixture explodes when rarefied 24 times; the latter ceases to explode when rarefied 18 times. Heat ex- trinsically 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 rare- fied 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 lam- bent 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 expanded 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. We shall now detail briefly the effects of rarefaction by heat on combustion and ex- plosion. Under CALORIC we have shown, that air by being heated from 32 to 212 expands ^ or 8 parts become 11 ; hence the expansion of one volume of air at 212" into 2 , or the augmentation of 1.5 = ^ which Sir H. Davy found to take place when the enclosing glass tube began to soften with ignition, will indicate 932. For -2- : 180 : : ~ : 720, to which if we add 212, the sum is 932. One of air at 212 becoming 2^, as took place in the other experiment of Sir H. Davy, will give us (180 X ~) -f- 2l2 a = 812, forthe heat of fusible metal lumin- ous in the shade. I believe these experi- ments to be much more accurate than a iy hitherto given, relative to the temperature of incandescence. This philosopher, whose ingenuity of research is usually guided by the most rigorous arithmetic, estimates the first temperature from the above data of Gay-Lussac, at 1035 FarenheSt. I there- fore hesitate to offer a discordant computa- tion. One volume of air at 212, should be- come at a temperature f 1035, accord- COM COM ing to the rule I use, 2.715 parts, instead of 2.5. 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 volume of the gas was increased from 1 to 2.5. By means of a blow-pipe and another lamp, he made the upper pait of the tube red-hot, when an explosion instantly took place. This experiment refutes the notions of M. de Groithus, 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 passed through. An ex- plosion took place, before the tube was red- hot. This fine experiment shows, that ex- pansion by heat, instead of dim.nishing the accendibility of g-ases, enables them, on the contrary, to explode apparently at a lower temperature ; which seems perfectly reason- able, as a part of the heat communicated by any ignited body, must be lost in gradually raising the temperature. M. de Grotthus has stated, that if a glow- ing coal be brought into contact with a mix- ture of oxygen and hydrogen, it only rare- fies them, but does not explode them. This depends on the degree of heat communica- ted by the coal. If it is red in day-light, and free from ashes, it uniformly explodes the mixture. If its redness be barely visi- ble in the shade, it will not explode them, but cause their slow combination. The gen- eral phenomenon is wholly unconnected with rarefaction; as is shown by the following cir- cumstance : When the heat is greatest, and before the invisible combination is comple- ted, if an iron wire, heated to whiteness, be placed upon the coal within the vessel, 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 in- troduced into a bladder furnished with a capillary tube. This tube was heated till it began to melt. The mixture was then pass- ed 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 explosive mixture, produced by the sudden expansion of another part by heat, or the electric spark, is not the cause of combus- tion, 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 bi-phosphuretted hydrogen gas and oxygen, which explode at a heut a little above that of boiling water, was con- fined by mercury, and very gradually heated on a sand bath. When the temperature of the mercury was 242, the mixture explo- ded. A similar mixture was placed in a re- ceiver communicating with a condensing syringe, and condensed over mercurv till it occupied only one-fifth of its original vo- lume. No explosion took place, and no che- mical change had occurred; for when its volume was restored it was instantly explo- ded 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 atmos- pheres, explosion or combustion occurs ; that is, bodies combine with the production of heat and light. Since it appears that gaseous matter ac- quires a double, triple, quadruple, Sec. 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 resulting compound gus occupy, alter cooling, the same bulk as the sum of its con- stituents. Now this is the case with chlo- rine and hydrogen, and with prussine and oxygen. The latter detonated in the pro- portion 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 their original btdk. Hence 15 x 480 = 7200 of Fahr. and the real temperature is probably much higher; for heat must be lost by communication to the tube and the water. The heat of the gaseous carbon in combustion in this gus, appears more intense than that of hydro- gen ; for it was found that a filament ot pla- tinum was fused by a flame of prussine (cy- anogen) 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 different gases, and those of different cool- ing orifices, on flame. In Sir H. Davy's first paper on the fire- damp of coal mines, he mentioned that car- bonic acid had a greater influence in de- stroying the explosive power of mixtures of firedamp ana air, than azote; and he sup- pose litfl t cause to be its greater density and COM oapacity for heat, in consequence of which it might exert a greater cooling agency, and thus prevent the temperature of the mixture from being raised to that degree necessary for combustion. He subsequently made a series of experiments with the view of de- termining how far this idea is correct, and for the purpose of ascertaining the general phenomena, of the effects of the mixture of easeous substances upon explosion and com- bustion. Prevented by Of hydrogen, 8 Oxygen, 9 Nitrous oxide, 11 Subcarburetted hydrogen, 1 Sulphuretted hydrogen, 2 Olefiant gas, Muriatic acid gas, 2 Chlorine, ...... COM He took given volumes, of a mixture of' two parts of hydrogen and one part of oxy- gen by measure, and diluting them with various quantities of different: elastic flu ; ds, he ascertained 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, inflamma= tion was Pennitted with. 6 7 10 Cdoline; power, air 2.66 1.12 0.75 (the mean) 2.18 (coal gas) 1.6 0.66 Silicated fluoric gas, Azote, Carbonic acid, - 1.33 . 0.727 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, according to Delaroche and Berard, has a greater capacity for heat, in the ratio of 1.3503 to 0.9765 by volume, has lower pow- ers of preventing explosion. Hydrogen al- so, which is fifteen 1 mes lighter than oxy- gen, and which in equal volumes 1ms a small- er capacity for heat, certainly has a higher power of preventing explosion; and oleft- ant gas exceeds all other gaseous substan- ces, in a much higher ratio than could liave 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 cooling 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 throughout 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 ab- stracting power by which they become quickly heated, and their capacity for heat, which is great in proportion as their tempe- ratures are less raised by this abstraction. The power of elastic fluids to abstract heat from solids, appears from the above experi- ments to be in some inverse ratio to their 3:!y j and there seems to be something in the constitution of the light gases, whick enables them to carry off' heat from solid surfaces in a different manner from that in which they would abstract it in gaseous mix- tures, 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 par- ticles can be of little consequence. Whatever be the cause of the different cooling powers of the different elastic fluids in preventing inflammation, very simple ex- periments show that they operate uniformly with respect to the different species of com- bustion; and that those explosive mixtures, or inflammable bodies, which require least heat for their combustion, require larger quantities of the different gases to prevent the effect, and vice versa. Thus one of chlo- rine and one of hydrogen still inflame when mixed with eighteen times their bulk of oxy- gen; whereas a mixture of carburetted hy- drogen and oxygen, in the proper propor- tions (one and t\vo) for combination, have their inflammation prevented by less than three times their volume of oxygen. A wax taper was instantly extinguished in air mixed with one-tenth of silicuted fluoric acid, and in air mixed with one-sixth of muriatic acid gns; but the flame of hydrogen burned rea- dily in those mixtures; arid in mixtures which extinguished the flame of hydrogen, the flame of sulphur burned. (See the beginning of sec- tion 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 mixture which prevents inflammation will ot prevent combination, that is, the COM COM 'wiH combine without any flash. If two vo- lumes of carburetted hydrogen be added to a mixture of one of chlorine with one of hydrogen, muriatic acid is formed through- out the mixture 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 carburetted 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 air, so neither does condensation considerably increase it; a cir- cumstance of great importance in the con- stitution of our atmosphere, which at all heights or depths, at which man can exist, still preserves the same relations to combus- tion. It may be concluded from the general law, that at high temperatures, gases not concerned in combustion will have less power of preventing that operation, and likewise that steam and vapours, which re- quire a considerable heat for their formation, will have less effect in preventing combus- tion, particularly of those bodies requiring low temperatures, than gases at the usual heat of the atmosphere. Thus, a very large quantity of steam is required to prevent sul- phur from burning. A mixture of oxygen and hydrogen will explode by the electric spark, though diluted with five times its vo- lume of steam ; and even a mixture of air and carburetted hydrogen gas, the least ex- plosive of all mixtures, requires a third of steam to prevent its explosion, 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 -j- was regarded as the cor- rection for the expansion of the gases. We. shall now treat f the effects of cooling drificcs on fame. The knowledge of the cooling power of elastic media, in preventing the explosion of the fire-damp, led the illus- trious English chemist, to those practical researches, which terminated in his grand discovery of the wire-gauze safe-lamp. The general investigation of ihe relation and ex- tent of those powers, serves to elucidate the operation of wire-gauze and other tissues or systems of apertures, permeable to light and air, in intercepting flame, and confirms the views originally given of this marvellous phenomenon. We have seen that^awe is gaseous matter, heated so highly as to be luminous, and that to a degree of tempera- ture beyond the white heat of solid bodies; for air not luminous will communicate this degree of heat. When an attempt is made to pass flame through a very fine mesh of wire-gauze of the common temperature, the gauze cools each portion of the elastic mat- - ter 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 the mesh, and to the mass of the metal. The power of a metallic or other tissue to prevent ex- plosion, will depend upon the heat required to produce the combustion, as compared with that acquired by the tissue. Hence, the flame of the most inflammable sub- stances, and of those that produce most heat in combustion, will pass through a metallic tissue, that will interrupt the flame of less inflammable substances, or those that produce little heat in combustion. Or the tissue being the same, and impermeable to all flames at common 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 temperature 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 tem- peratures, will pass through a tissue suffi- ciently large, not to be immediately choaked up by the phosphoric acid formed, and the phosphorus deposited. If a tissue, contain- ing above 700 apertures to the square inch, be held over the flame of phosphorus or phosphuretted hydrogen, it does not trans- mit the flame till it is sufficiently heated to enable the phosphorus to pass through it in vapour. Pnosphuretted hydrogen is decom- posed by flame, and acts exactly like phos- phorus. In like manner a tissue of 108 apertures to the square inch, made of a wire of TxF* will > at comrn n temperatures, inter- cept 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 olefiani 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 hydrogen. The latter gas re- quires a considerable mass of heated metal to inflame it, or contact with an extensive heated surface. An iron wire of l-20th or" an inch, and eight inches long, red-hot, when held perpendicularly in a stream of coal gas, did not inflame 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 perpendicu- larl), in a bottle containing an explosive mixture, so that heat was communicated successively to portions of the gas, produced its COM COM The scale of gaseous accension, given in the first section, explains, why so fine a mesh of wire is required to hinder the ex- plosion from hydrogen and oxygen, to pass; and why so coarse a texture and wire, con- troul the explosion of fire-damp. The ge- neral 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 600 or 700 apertures to the square inch, is held over the flame, fumes of condensed sulphur immediately come through it, and the flame is intercept- ed. The fumes continue for some instants, but on the increase of the heat, they dimi- nish; and at the moment when they disap- pear, which is long before the gauze be- comes red-hot, the flame passes; the tem- perature at which sulphur burns being that at vrhich it is gaseous. Where rapid currents of explosive mix- tures, 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. Hut, by increasing the cooling sur- face, by diminishing the apertures in size, or increasing their depth, all fames, however rapid their motion, may be arrested. Pre- cisely the same law applies to explosions acting in close vessels. Very minute aper- tures, when they are only few in number, will permit explosions to pass, which are arrested by much larger apertures when they Mil a whole surface. A small aperture was drilled at the bottom of a wire-gauze lamp, itt the cylindrical ring, which confines the gauze. This, though less than -i- of an inch in diameter, transmitted the flame, and tired the external atmosphere, in conse- q/uence 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, -.huii these simple facts and observations, that the interruption of flame, by solid tis- sues, permeable to light and air, depends opon no recondite or mysterious cause, but MI their cooling powers, simply considered as such. When a light, included in a cage of wire -gauze, is introduced into an explo- sive atmosphere of fire-damp at rest, the maximum of heat is soon obtained ; the ra- diating power of the wire, and the cooling eiJ'ectof the atmosphere, 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 feeat common gauze to a higher tempera- ture, twilled gauze, in which the radiating surface is considerably greater, and the cir- culation of air less, preserves an equable temperature. Indeed, the heat communi- cated to the wire by combustion of the fire- damp in wire-gauze lamps, is completely in the power of the manufacturer. By diminish- ing 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 -i- 16 to the warp, and 30 to the weft, ri vetted 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 con- venient 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 dan- gerous mines of England, without any acci- dent. Whatever explosive disasters have happened since, may be imputed to the ne- glect, or gross and culpable mismanagement, of that infallible protector. See LAMP. When the fire-dump is inflamed in the wire-gauze cylinders, coal dust thrown into the lamp, burns with strong flushes and scin- tillations. 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, pow- dered rosin, and witch-meal, through lamps burning in more explosive mixtures, than ever occur in coal mines; and though he kept these substances floating in the explo- sive atmosphere, and heaped them upon the top of the lamp when it was red-hot, no ex- plosion could ever be communicated. Phos- phorus or sulphur, are the only substances which can produce explosion, by being ap- plied to the outside of the lamp ; and sul- phur, to produce the effect, must be appli- ed in large quantities, and fanned by a cur- rent of fresh air. He has even blown re- peatedly, fine coal dust mixed with minute quantities of the finest dust of gunpowder, through the lamp burning in explosive mix- tureSj without any communication of explo- sion. The most timorous female might traverse an explosive coal mine, guided by the light of the double cylinder lamp, with- out feeling the slightest apprehension. 5. We have now arrived at the most cu- rious 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, i COM COM 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 great- est heat that can be given without making glass luminous in darkness, the combina- tion 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 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 ex- plosion takes place. With small quantities of gas, the invisible combustion is complet- ed in less than a minute. It is probable that the slow combination without combus- tion, long ago observed with respect to hy- drogen and chlorine, oxygen and metals, will happen at certain temperatures with most substances that unite by heat. On trying charcoal, he found, that at a tempe- rature which appeared to be a little above the boiling point of quicksilver, it convert- ed 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 explo- sion. 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 ne- cessary for the ignition of solid bodies, it appeared probable, that in these silent combinations of gaseous bodies, when the increase of temperature may not be suffi- cient to render the gaseous matters them- selves luminous, yet it still might be ade- quate to ignite solid matters exposed to them. Sir H. Davy had devised several experi- ments on this subject. He had intended to expose fine wires to oxygen and olefiant g-as, and to oxygen and hydrogen, during their slow combination under different cir- cumstances, 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 phenomena. He was making experiments on the in- crease of the limits of the combustibility of gaseous mixtures of coal-gas and air, by increase of temperature. For this pur- pose, a small wire-gauze safe-lamp, with fine wire of platinum fixed above the flame, was introduced into a combustible mixture, containing the maximum of coal- gas. When the inflammation 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 cylinder. 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, combin- ed without flame, and yet produced heat enough to preserve the wire ignited, and keep up their own secret combustion. The truth of this conclusion was proved by in- troducing a heated wire of platinum into a similar mixture. It immediately became ignited nearly to whiteness, as if it had been in actual combustion itself, and con- tinued glowing for a long while. When it was extinguished, the inflammability of the mixture was found to be entirely destroyed. A temperature much below ignition only, was necessary for producing this curious phenomenon, 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 red- hot. The same phenomena were produced with mixtures of olefiant gas and air, car bonic oxide, prussic gas, and hydrogen; and in this last case with a rapid produc- tion- of water. The degree of heat could be regulated by the thickness of the wire. When of the same thickness, the wire be- came more ignited in hydrogen, than iu mixtures of olefiant gas, and more in mix- tures of olefiant gas, than in those of gase- ous 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 ex- plode them. The same wire in less com- bustible mixtures, continued merely bright red, or dull red, according to the nature of the mixture. In mixtures not explosive bv 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, al- cohol, oil of turpentine, naphtha, and cam- phor, have been tried. There cannot be a better mode of illustrating the fact, than by an experiment on the vapour of ether 9T of alcohol, which any person may make COM COM 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 pla- tinum, of the l-60ih or 1.70th 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 forma- tion of a peculiar acrid volatile substance, possessed of acid properties. See ACID (LAMPIC). The above experiment has been ingeniously varied by sticking loose- ly on the wick of a spirit lamp, a coil of fine platinum wire, about j^-$ of an inch in thickness. There should be about 16 spiral amis, one-half of which should sur- Kound 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 cylin- der of camphor may be substituted for both wick and spirit. The ignition is very bright, and exhales an odoriferous vapour. With oil of turpentine^ the lamp burns in- visibly without igniting the wire; for a dense column of vapour is perceived to as- cend from the wire, diffusing a smell by many thought agreeable. By adding essen- tial 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 ef- fect ceases after a certain time. The chemical changes in general, pro- iuced by slow combustion, appear worthy f investigation. A wire of platinum in- troduced under the usual circumstances into a mixture of prussic gas (cyanogen), nnd oxygen in excess, became ignited to whiteness, and the yellow vapours of ni- irous acid were observed in the mixture. In a mixture of defiant 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 phenome- na. A film of carbon or sulphur deprives ven these metals of this property. Thin laminae of the metals, if their form admits of a free circulation of air, answer as well as fine wires; and a large surface of plati- num may be made red-hot in the vapou" of ether, or in a combustible mixture of coal gas and air. Sir H. Davy made an admirable practical application of these new facts. By hang- ing some coils of fine 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 ex> tinguished by the quantity of fire-damp, the glow of the platinum will continue to guide him; and by placing the lamp in dif- ferent parts of the gallery, 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 respi- ration wherever the wire continues ignit- ed; for even this phenomenon ceases, when the foul air forms about f 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 pla- tinum, about 2 inches above the lighted wirk. This apparatus was placed in a large receiver, in which, by means of a gas-holder, the air could be contaminated. to any extent with coal-gas. As soon as there was a slight admixture of coal-gas, the platinum became ignited. The igni- tion 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 platinum, at the mo- ment of the extinction, became white hot, presenting a most brilliant light. By in- creasing the quantity of the coal-gas still fui'ther, the ignition of the platinum be- came less vivid. When its light was bare- ly sensible, small quantities of air were ad- mitted, and it speedily increased. By re- gulating 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 atmosphe ric 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 suffi- cient heat, to enable the fine platinum wire to rekindle in a proper mixture half a mi- nute after its light had been entirely des- troyed, by an atmosphere of pure coal-gag. The phenomenon of the ignition of the pla- tinum, takes place feebly in a mixture con- sisting of two of air and one of coal-gas; and brilliantly in a mixture consisting of three of air and one of coal-gas. The greater 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. COM COM mixture (that is, containing- more inflam- mable 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 mix- ture, and the same gaseous matter will be found to be inflammable, and to be a sup- porter of combustion. When a large cage of wire of platinum is introduced into a very small safe-lamp, even explosive mix- tures of fire-damp are burned without flame; and bv placing 1 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 protrude through the wire-gauze. It is truly wonderful, that a slender tissue of platinum, which does not cost one shilling, and which is imper- ishable, should afford in the dark and dan- gerous recesses of a coal mine, a most bril- liant light, perfectly safe, in atmospheres in which the flame of the safety-lamp is extinguished; and which glows in every mixture of carburetted hydrogen gas that is respirable. When the atmosphere be- comes again explosive, the flame is re- lighted. 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 combustion with some practical inferences. The facts detailed on insensible com- bustion, explain why so much more heat is obtained from fuel, when it is burned quickly than slowly; and they show, that in all cases the temperature of the acting bo- dies should be kept as high as possible, not only because the general increment of heat is greater, but likewise because those combinations are prevented, which, at lower temperatures, take place without 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 communicated to the matters entering into inflammation. 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 in- dicate methods by which temperature may be increased, and the limits to certain me- thods. Currents of flame can never raise VOL. I. the heat of bodies exposed to them, high- er than a certain degree, that is, their own temperature. But by compression, there can be no doubt, that the heat of flameg from pure supporters and combustible matter may be greatly increased, probably in the ratio of their compression. In the blow -pipe of oxygen and hydrogen, the maximum of temperature is close to the aperture from which the gases are disen- gaged, that is, where their density is greatest. Probably a degree of tempera- ture far beyond any that has yet been at- tained, may be produced by throwing the flame from compressed oxygen and hydro- gen into the voltaic arc, and thus combin- ing the two most powerful agents for in- creasing 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, the first deposited and afterwards burned. The form of the flame is conical, because the greatest heat is in the centre of the explo- sive mixture. In looking stedfastly at flame, the part where the combustible mat- ter 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 explosive. The heat diminishes towards the top of the flame, because in this part the quanti- ty of oxygen is least. When the wick in- creases to a considerable size, from col- lecting charcoal, it cools the flame by ra- diation, and prevents a proper quantity of air 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 flames in the atmosphere is increased by condensa- tion and diminished by rarefaction, appa- rently 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 capa- ble of emitting light, absorb heat, which could not be the case in the condensation 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. Halley calculated the height of a meteor at ninety miles, and the great American meteor which threw down showers of stones, was estimated at seven- teen miles high. The velocity of motion of these bodies must in all cases be im- mensely great, and the heat produced by 42 cox cox the compression of the most ratified air, from the velocity of motion, must be pro- bably sufficient to ignite the mass. All the phenomena may be explained, if falling stars be supposed to be small solid bodies moving around 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 com- bustible or elastic matter. When the common electrical or voltaic electrical spark is taken in rare air, the light is considerably diminished, as well as the heat. Yet, in a receiver that con- tained air 60 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 Institution, 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 Borealis and Mustralis. 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 decomposition; that is, to the internal motions of the particles of bodies, tending to arrange them in a neiv 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 hy- drogen.* COMPTONITE. A new mineral, found in drusy cavities, in ejected masses, on Mount Vesuvius. It occurs crystallized, in straight four-sided prisms, which are usually truncated on their lateral edges, so as to form eight-sided prisms, termina- ted with flat summits. Transparent, or semi-transparent. Gelatinizes with acids. It is sometimes accompanied with acicular Arragonite. It was first brought to this country by Lord Coinpton, in 1818. * CONCRETIONS (MORBID). Solid de- posites, 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. Deposites 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 perfected 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 some 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 guage, he says, ** 1 now put some sulphu- ric 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 vapour." He was thus enabled by this artificial dryness to exhibit certain electrical phenomena to great ad- vantage. 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. Woulfe, I was very desirous to try whether 1 could produce any considerable degree of cold by the evaporation of ether under a receiver whilst exhausting." Accordingly he suc- ceeded in sinking a thermometer, whose bulb was from time to time dipped into the ether in vacuo, 103 below 56, the temperature of the apartment. Mr. Nairne made no attempt to condense the vapour in vacuo by chemical means, and thus to favour its renewed formation from the li- quid surface; which I consider to be the essence of Professor Leslie's capital im- provement, on Cullen's plan of artificial re- frigeration. After Nairne's removing the vapour of water by sulphuric acid to pro- duce artificial dryness, there was indeed but a slight step to the production of arti- ficial cold, by the very same arrangement; but still this step does not appear to have been attempted by any person from the year 1777 till 1810, when Professor Leslie was naturally led to make it, by the train CON CON of his researches on evaporation and hy- gTometry. The extreme rapidity of evaporation in vacuo, may be inferred from Dr. Robison's position, that all liquids boil in it, at a temperature 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 compensate in a considerable degree for its inferior ra- pidity of vaporization. In the month of June 1810, Professor Leslie having introduced a surface of sul- phuric 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, to- tally disappeared. When the air has been rarefied 250 times, the utmost that under such circumstances can perhaps be effect- ed, the surface of evaporation is cooled down 120 Fahrenheit in winter, and would probably, from more copious evaporation and condensation, sink near 200 in sum- mer. If the air be rarefied only 50 times, a depression of 80, or even 100, will be produced. We are thus enabled by this elegantcom- 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 great- er extent; for otherwise the moisture would exhale more copiously than it could be transferred and absorbed, and consequent- ly 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 con- gelation may be contained in a shallow cup, about half the width of the dish, and hav- ing its rim suppoi'ted by a narrow porce- lain ring, upheld above the surface of the acid by three slender feet. It is of conse- quence that the water should be insulated as much as possible, or should present only a humid surface to the contact of the sur- rounding 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 inconvenience 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 view- ed most completely; yet when they are formed of a bright metal, the effect ap- pears, on the whole, mom striking. But the preferable mode, and that which pre- vents any waste of the powers of refrigera- tion, is to expose the water in a saucer of porous earthen ware. At the instant of congelation, a beautiful network of icy spi- culae pervades the liquid mass. The disposition of the water to fill the receiver 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 baro- metrical 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, I have been accustomed for many years to recommend the employment of a series of cast-iron plates, attachable by screws and stop-cocks to the air-pump. Each iron disc has a receiver adapted to it. Thus, we may with one air-pump, successively put any number of freezing processes in ac- tion. A cast-iron drum of considerable di- mensions being filled with steam, by heat- ing 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 trans- ferrer 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 rarefaction to this degree would be effected in a moment by a turn of the stop-cock; and on its be- ing 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 pub- CON COP licly recommended by me upwards of ten years ago, when I had a glass model of it made for class illustration. The combined powers of rarefaction, va- porization, 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 fffoss threads near a broad surface of sulphuric acid, under a receiver, on urging the rare- faction, it will become frozen, and may be kept in the solid state for several hours. Or otherwise, having introduced mercury 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. Af- ter 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 re- ceiver 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 be- low 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 sur- rounds the receiver. When the acid has acquired one-tenth of water, its refrigerating power is diminish- ed only one-hundredth. When the quan- tity of moisture is equal to one-fourth of the concentrated acid, the power of gene- rating 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 effect- ing the congelation of more than twenty times its weight of water, before it has im- bibed nearly its own bulk of that liquid, or has lost about one-eighth of its refrige- rating 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 be- fore a kitchen-fire, and allowed to cool in close vessels. With a body of this, a foot in diameter, and an inch deep, Professor Leslie froze a pound and a quarter of wa- ter, contained in a hemispherical porous cup. Muriate of lime in ignited poi'ous pieces, may also be employed as an ab- sorbent. Even mouldering trap or whin- stone, has been used for experimental il- lustration 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 su- gar canes, or dried stalks of Indian corn. On this bed are placed rows of small un- glazed 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 arc filled with soft water, previously boiled and suffered to cool. When the weather is very fine and clear, a great part of the water becomes frozen during the night. The pans are regularly visited at sunrise, and their contents emptied into baskets which retain the ice. These are now car- ried to a conservatory made by sinking a pit 14 or 15 feet deep, lined with straw un- der a layer of coarse blanketing. The small sheets of ice are thrown down into the ca- vity, 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 inte- resting subject, see the sequel of the arti- cle DEW.* * CONITE. An ash or greenish -gray co- loured mineral, which becomes brown on exposure to the air. It is massive or stalac- titic, is dull internally, and has a small grained uneven fracture. It is brittle; sp. gr. 2.85. It dissolves in nitric acid, with slight effervescence, and blackens without fusing before the blow-pipe. Its constitu- ents are 67.5 carbonate of magnesia, 28 carbonate of lime, 3.5 oxide of iron, and 1 water. It is found in the Meissner trap hill in Hessia, 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 Kil- patrick, and the Isle of Sky." COPAL, improperly called gum copal, is a hard, shining, transparent, citron -colour- ed, odoriferous, concrete juice of an Ame- rican tree, but which has neither the solu- bility in water common to gums, nor the solubility in alcohol common to resins, at least in any considerable degree. By these properties it resembles amber. It may be dissolved by digestion in linseed oil, ren- COP COP dered drying by quicklime, with a heat very little" less than sufficient to boil or de- compose 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 applied 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 re- flecting light more uniformly. Mr. Sheldrake has found, that camphor has a powerful action on copal; for if pow- dered copal be triturated with a little cam- phor, it softens, and becomes a coherent mass; and camphor added either to alcohol or oil of turpentine, renders it a solvent of copal. Half an ounce of camphor is suffi- cient for a quart of oil of turpentine, which should be of the best quality; and the co- pal, about the quantity 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 almost immedi- ately; and the vessel Mr. S. recommends to be of tin or other metal, 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 quan- tity of camphor it contains, that oil of la- vender 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 manage- ment of the fire that it seldom succeeds completely. * In the 51st volume of Tilloch's Maga- zine, Mr. Cornelius Varley states, that a good varnish may be made by pouring upon the purest lumps of copal, reduced to a fine mass, in a mortar, colourless spirits of tur- pentine, to about one-third higher than the copal, and triturating the mixture occa- sionally in the course of the d?.y. Next morning it may be poured off' into a bottle for use. Successive portions of oil of tur- pentine may thus be worked with the same copal mass. Camphorated oil of turpen- tine, and oil of spike-lavender, are also re- commended as separate solvents without trituration. The latter, however, though very g'ood for drawings or prints, will not do for varnishing pictures, as it dissolves the paint underneath, und runs down while drying.* COPPER is a metal of a peculiar reddish- brown colour; hard, sonorous, verv mallea- ble and ductile; of considerable tenacity, and of a specific gravity from 8.6 to 8.9, At a degree of heat far below ignition, the surface of a piece of polished copper be- comes covered with various ranges of pris- matic colours, the red of each order being nearest the end which has been most heat- ed; an effect which must doubtless be at- tributed to oxidation, the stratum of oxide being thickest where the heat is greatest, and growing gradually thinner and thinner towards the colder part. A greater de- ree of heat oxidizes it more rapidly, so that it contracts 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 me- tallic state. Copper rusts in the airj but the corroded part is very thin, and preserves the metal beneath 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 -j- 2 oxygen. It is a deutoxide. The pro- toxide is obtained by digesting a solution of muriate of copp'er with copper turn- ings, in a close phial. The colour passes from green to dark brown, and gray crys- talline grains are deposited. The solution of these yields, by potash, a precipitate of an orange colour, which is the protoxide. It consists of 8 copper -{- 1 oxygen. Pro- toxide of copper has been lately found by Mr. Mushet, in a mass of copper, which had been exposed to heat for a considera- ble time, in one of the melting furnaces of the mint under his superintendence. Copper, in filings, or thin laminae, intro- duced into chlorine, unites with flame into the chloride, of which there are two varie- ties; the protochloride, a fixed yellow sub- stance, and the cleutochloride, a yellowish- brown pulverulent sublimate. 1. The crys- talline grains deposited from the above mu- riatic solution, are protochloride. The pro- tochloride is conveniently made by heating together two parts of corrosive sublimate, and one of copper filings. An amber- coloured translucent substance, first dis- covered 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 :* narrow orifice, is not de- composed or sublimed by a strong red heat. Rut if air be admitted it is dissipated in dense white fumes. It is insoluble in wa- ter. It effervesces in nitric acid. It dis- solves silently in muriatic acid, from which it may be precipitated by water. By slow cooling of the fused mass Dr John Davy obtained it crystallized, apparently in small plates, semitransparent, and of a light yel- COP low colour. It consists, by the same inge- nious chemist, of Chlorine, 36 or 1 prime = 4.45 35.8 Copper, 64 or 1 prime 8.00 64.2 100 12.45 100.0 2. Dentochloride is best made by slowly evaporating to dryness, at a temperature not much above 4-00 Fahr. the deliques- cent muriate of copper. It is a yellow pow- der. By absorption of moisture from the air, it passes from yellow to white, and then green, reproducing- common muriate. Heat converts it into protochloride, with the disengagement of chlorine. Dr. Davy ascertained the chemical constitution of both these compounds, by separating the copper with iron, and the chlorine by ni- trate of silver. The deutochloride consists of Chlorine, 53 2 primes 8.9 52-7 Copper, 47 1 do. 8.0 47-3 100 16.9 1000 The iodide of copper is formed by drop- ping aqueous hydriodate of potash into a solution of any cupreous salt It is an in- soluble dark brown powder. Phosphuret 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 crystallizes in tour-sided prisms. Proust, its discoverer, says it consists of 20 phos- phorus -f- 80 copper. 1.5 or 3.0 phospho- rus -f- 8.0 copper, form the equivalent pro- portions by theory. Heat burns out the phosphorus, and scorifies the copper. 8-ulphuret 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 tempera- ture, combustion suddenly pervades the whole mass with explosive violence. Ignition, with reciprocal saturation, con- stitutes a true combustion, of which every character is here. And since the experi- ment succeeds perfectly well in vacua, or in azote, we are entitled to consider sul- phur as a true supporter of combustion, if this name be retained in chemistry; a name indicating, what no person can prove, that one of the combining bodies is a mere sup- porter, and the other a mere combustible. Combustion is, on the contrary, shown by this beautiful experiment, to be indepen- dent of those bodies vulgarly reckoned supporters. Indeed, sulphur bears to cop- per the same electrical relation, that oxy- gen and chlorine bear to this metal. Hence sulphur is at once a supporter and com- bustible, in the fullest sense; a fact fatal to this technical distinction, since one body cannot be possessed of diametrically op- posite qualities. COP When a disc of copper, with an insulat- ed handle, is made to touch a disc of sul- phur, powerful electrical changes ensue; and at a higher temperature we see, that the reciprocal attractive forces, or the cor- puscular movements which accompany en- ergetic affinity, excite the phenomena of combustion. To say that one of the com- bining bodies contains a latent magazine of heat and light, to feed the flame of the other body, is an hypothesis altogether des- titute of proof, which should therefore have no place in one of the exact sciences, far less be made the groundwork of a che- mical system. Sulphuret of copper consists, according to Berzelius, of very nearly 8 copper -f- 2 sulphur. We may regard it as containing a prime of each constituent.* The 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 cop- per, but redissolves the oxide, and pro- duces a deep blue colour. There are cer- tain mineral waters in Hungary, Sweden, Ireland, and in various parts of England, which contain sulphate of copper, and from which it is precipitated by the addi- tion of pieces of old iron. Nitric acid dissolves copper with great rapidity, and disengages a large quantity of nitrous gas. Part of the metal falls down in the form of an oxide; and the fil- trated or decanted solution, which is of a much deeper blue colour than the sulphu- ric solution, affords crystals by slow eva- poration. This salt is deliquescent, very soluble in water, but most plentifully when the fluid is heated. Its solution, exposed to the air in shallow vessels, deposites an oxide of a green colour. Lime precipi- tates the metal of a pale blue, fixed alkalis of a bluish-white. Volatile alkali throws down bluish flocks, which are quickly re- dissolved, 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 cop- per. They have the following general cha- racters: 1. They are mostly soluble in water, and their solutions have a green or blue colour, or acquire one of these co- lours on exposure to air. 2. Ammonia added to the solutions, produces a deep blue colour. 3. Ferroprussiate of potash gives a reddish-brown precipitate, with cu- preous salts. 4. Gallic acid gives a brown COP COP preciqitate. 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 prot- oxide of copper can be combined with the acids only by very particular management. All the ordinary salts of copper have the peroxide for a base. Acetate of copper. The joint agency of air and acetic acid, is necessary to the pro- duction of the cupreous acetates. By ex- posing- copper plates to the vapours of vine- gar, the bluish-green verdigris is formed, which by solution in vinegar constitutes acetate of copper. This salt crystallizes in four-sided truncated pyramids. Its colour is a fine bluish-green. Its sp. gr. is 1.78. It has an austere metallic taste; and swal- lowed, proves a violent poison. Boiling water dissolves one-fifth of the salt, of which it deposites the greater part on cool- ing. It is soluble also in alcohol. It ef- floresces by exposure to air. By heat, in a retort, it yields acetic acid, and pyro-ace- tic spirit. Sulphuretted hydrogen throws down the copper from solutions of this salt, in the state of sulphuret. Dr. Thom- son gives the following account of its com- position: " According to Proust, the ace- tate of copper is composed of 61 acid and water, 39 oxide, 100 *' If we suppose it a compound of 1 atom acid, 1 atom oxide, and 8 atoms water, its constituents will be Acetic acid, 25.12 Peroxide of copper, 39.41 Water, 35.47 100.00 "I consider these to be its true constitu- ents." Here we have an amusing specimen of atomical reasoning; beginning the syllo- gism with a supposition, and concluding it with a certainty. 1 had occasion to ana- lyze this salt with some care about two years ago, and found it to consist by expe- riment 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 consist of acid and water, 37 Oxide, 63 The proportion of 40 acid -f- 60 oxide, is that of 1 atom of each, to use the hypo- pothetical term. Now Proust's experiments seem to leave uncertainty to the amount of that difference. This salt should be called probably the acetate. Proust's insoluble part of verdigris will become the subace- tate. This constitutes 44 per cent, and the other 56. But the proportions will fluctu- ate; and an intermixture of carbonate may be expected occasionally. Jlrseniatc of copper presents us with many sub-species which are found native. The arseniate may be formed artificially by di- gesting arsenic acid on copper, or by ad- ding arseniate of potash to a cupreous sa- line solution. 1. Obtuse octahedral araeniate, 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 con- sist, according to Chenevix, of 14.3 acid -j- 50 brown oxide -f- 35.7 water. 2. Hex- ahedral arseniate is found in fine six-sided laminae, divisible into thin scales. Its co- lour is a deep emerald-green; and its sp. gr. 2.548. It consists, by Vauquelin, of 43 acid -f- 39 oxide -f- 18 water. When arse- niate of ammonia is poured into nitrate of copper, this variety precipitates in small blue crystals. 3. Acute octahedral arseniate, com- posed of two four-sided pyramids, applied base to base, and sometimes in rhomboidal prisms, with dihedral summits. It con- sists of 29 acid -f- 50 oxide -f- 21 water. The last ingredient is sometimes wanting. 4. Trihedral urseniate occurs also in other forms. Colour bluish-green. It consists, by Chenevix, of 30 acid -f- 54 oxide, -f- 16 water. 5. Superarseniate. On evaporating the supernatant solution in the second va- riety artificially made, and adding alcohol, M. Chenevix obtained a precipitate in small blue rhomboidal crystals. They were composed of 40.1 acid -}- 35.5 oxide 4- 24.4 water. The following is a general ta- ble of the composition of these arseniates: 100.0 25.51 100.00 Instead of 35^ per cent of water, which the Doctor pitches on at random, it has not 9; and instead of only 25 of acid, it really contains more than double that quantity. The crystallized salt is a binacetate of dip- per. The subacetate of Proust, obtained by dissolving verdigris in water, is said to Add. 1.00 1.00 1.00 1.00 1.00 Oxide. 3.70 2.76 1.72 1.80 0.88 Water. 250 1.00 0.70 0.53 0.60 It will require the atomical couch of Pro- crustes, to accommodate these proportions to the number 14.5, recently pitched upon for arsenic acid by Dr. Thomson. Arsenite of copper, called Scheele's green, is prepared by the old prescription of mix- ing- a solution of 2 parts of sulphate of copper in 44 of water, with a solution of 2 parts of potash of commerce, and 1 of pulverized ai'senious acid, also in 44 of COP COP 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. Phillips, the following is th* or- der of their composition: 1st. 3d. 3J. Carbonic acid, 2 "5 11 OJ 2.75 Deutox. copper, 10.00 30.00 10.00 Water, I. US 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 grayish-white powder. Protomwiate 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 evapoi*ation crystals of a grass- green colour, in the form of rectangular pa- rallelepipeds. 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 lOOO The ammonia-nitrate evaporated, yields a fulminating copper. Crystals of nitrate, mixed with phosphorus, and struek with a hammer, detonate. When pulverized, then slightly moistened, and suddenly wrapt up firm, in tin-foil, the nitrate produces an explosive combustion. The nitrate seems to consist of a prime of acid -j- a prime of deutoxide, besides water of crystallization. Subnitrate of copper is the blue precipi- tate, 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. 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 10000 31.25 100.0 A mixed solution of this sulphate and sal ammoniac, forms an ink, whose traces are invisible 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 qua- drangular prisms. Mr. Proust formed a subsulphate by ad- ding 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 combines with the acid. The sulphate, si- multaneously produced, dissolves in the water; while the sulphite forms small red crystals, from which merely long ebulli- tion in 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, consisting of minute crystals, falls. Ammonia-sulphate of copper is the salt formed by adding water of ammonia to solution of the bisulphate. It consists, ac- cording to Berzelius, of 1 prime of the cupreous, and 1 of the ammoniacal sul- phate, combined together; or 20.0 -f- 7.13 -f- 14.625 of water. Subsulphate of ammonia and copper is formed by adding alcohol to the solution of the preceding salt, which precipitates the subsulphate. It is the cuprum ammoni- acum of the pharmacopoeia. According to Berzelius, it consists of Acid, 32.25 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 greenish-coloured, flat paral- lelopipedons. It seems to consist of * primes of sulphate of potash + 1 prime of bisulphate of copper + 12 of water. The following acids, antimonic, anti- monious, boracic, chromic, molybdic, phos- phoric, 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 so- luble. The oxalate is also green. The binoxalates of potash and soda, with ox- ide of copper, give triple salts, in green needle-form crystals. There are also am- monia-oxalates in different varieties. Tar- trate of copper forms dark bluish-green crystals. Cream-tartrate of copper is a bluish-green powder, commonly called Brunswick Green. To obtain pure copper for experiments, COP COP we precipitate it in the metallic state, by immersing- a plate of iron in a solution of tlie 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 solution of muriate of ammonia over cop- per tilings or shreds in a close vessel, keep- ing the mixture in a warm place, and ad- ding 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 wit!) ceruse. This metal combines very readily witli gold, silver, and mercury. It unites im- perfectly with iron in the way of fusion. Tin combines with copper, at a tempera- ture much lower than is necessary to fuse the copper alone. On this is grounded the method of tinning copper vessels. For this purpose, they are first scraped or scoured; uf'ter which they are rubbed with sal am- moniac. They are then heated, and sprink- led with powdered resin, which defends the clean surface of the copper from ac- quiring the slight film of oxide, that would prevent the adhesion of the tin to its sur- face. The melted tin is then poured in, and spread about. An extremely small quantity adheres to the copper, which may perhaps be supposed insufficient to prevent the noxious effects of the copper, as per- fectly 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 component parts. The uses of this hard, sonorous, and durable composition, in the fabrication of cannon, bells, statues, and other articles, are well known. Bronzes and bell-metals are not usually made of copper and tin only, but have other admix- tures, consisting of lead, zinc, or arsenic, according to the motives of profit, or other inducements of the artist. But the atten- tion 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 tele- scopes are made. See SPECULUM. The ancients made cutting instruments of this alloy. A dagger analyzed by Mr. Hiel m consisted of 83-j 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 bv various other VOL. I. names, according to the proportions of the two ingredients. It is not easy to unite these two metals in considerable propor- tions 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 cementation. 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 foul* feet deep, and continually renewed: to pre- vent the dangerous explosions of this me- tal, it is necessary to pour but a small quan- tity at a time. There are various methods of combining this granulated copper, or other small pieces of copper, with the va- pour of zinc. Calamine, which is an ore of zinc, is pounded, calcined, and mixed with the divided copper, together with a portion of charcoal. These being exposed to the heat of a wind furnace, the zinc be- comes revived, rises in vapour, and com- bines with the copper, which it converts into brass. The heat must be continued for a greater or less number of hours, ac- cording to the thickness of the pieces of copper, and other circumstances; and at the end of the process, the heat being sud- denly 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 powdered calamine, being mixed with an equal quantity of charcoal and a portion, of clay, is to be rammed into a melting ves- sel, and a quantity of copper, amounting to two-thirds of the weight of calamine, must be placed on the top, and covered with char- coal. By this management the volatile zinc ascends, and converts the copper into brass, which flows into the rammed clay; conse- quently, if the calamine contain lead, or any other metal, it will not enter into the 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 Germany; 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 colour. It does not readily unite with man- ganese. "With tungsten it forms a dark brown spongy alloy, which is somewhat ductile. Seen ORES or COPPER. * Verdigris, and other preparations of copper, act as virulent poisons, when intro- duced in very small quantities into the sto- machs of animals. A few grains are suf- ficient for this effect. Death is commonly preceded "by very decided nervous disgr- 43 COR ders, such as convulsive movements, te- tanus, general insensibility, or a palsy of the lower extremites. This event happens frequently so soon, that it could not be oc- casioned 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 circulation, acts on the brain and nerves. The cupreous preparations are no doubt very acrid, and if death do not follow yieir immediate impression on the sentient sys- tem, they will certainly inflame the intes- tinal canal. The symptoms produced by a dangerous dose of copper are exactly similar to those which are enumerated un- der arsenic, only the taste of copper is strongly felt. The only chemical antidote to cupreous solutions whose operation is well understood, is water strongly impreg- nated 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 caoutchouc tube, a solution in acetic acid, of four French drachms of ox- ide of copper. Some minutes afterwards he injected into it four ounces of strong sirup. He repeated this injection every half-hour, and employed altogether 12 ounces of sirup. The animal experien- ced some tremblings and convulsive move- ments. But the last injection was follow- ed by a perfect calm. The animal fell asleep, and awakened free from any ail- ment. Orfila relates several cases of individuals who had by accident or intention swallow- ed 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 swal- lowed with impunity, provided it was mix- ed with a considerable quantity of sugar. As alcohol has the power of completely neutralizing, in the ethers, the strongest muriatic and hydriodic acids, so it would appear, that sugar can neutralize the ox- ides of copper and lead. The neutral sac- charate of lead, indeed, was employed by Berzelius in his experiments, to determine the prime equivalent of sugar. If we boil for half an hour, in a flask, an ounce of white sugar, an ounce of water, and 10 grains of verdigris, we obtain a green li- quid, which is not affected by the nicest tests of copper, such as ferroprussiate of potash, ammonia, and the hydrosulphurets. An insoluble green carbonate of copper re- mains at the bottom of the flask.* COPPERAS. Sulphate of iron. * CORALS seem to consist of carbonate of lime and animal matter, in equal pro- portions.* 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 (SUBE- RIC). * Cork has been recently analyzed by Chevreul by digestion, first in water and then in alcohol. By distillation there came over an aromatic principle, and a little ace- tic acid. The watery extract contained a yellow and a red colouring matter, an un- determined 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 of the cork still weighed 14 parts, which is called suber.* CORK (Fossil,). See ASBESTOS. CORROSIVE SUBLIMATE. See MERCU- RY. * CORUNDUM. According to Professor Jameson, this mineral genus contains 3 spe- cies, viz. octahedral corundum, rhomboidal corundum, and prismatic corundum. 1. Octahedral, is subdivided into 3 sub- species, viz. automalite, ceylanite, and spi- nel. 2. Rhomboidal corundum, contains 4 sub- species, viz. salamstone, sapphire, emery, and corundum, or adamantine spar. 3. Prismatic, or chrysoberyl. See the several sub-species, under their titles in the Dictionary.* * COTTON. This vegetable fibre is solu- ble in strong alkaline leys. It has a strong affinity for some earths, particularly alu- mina, several metallic oxides, and tannin. Nitric acid, aided by heat, converts cotton into oxalic acid.* * COUCH. The heap of moist barley about 16 inches deep on the malt-floor.* * CREAM. The oily part of milk, which rises to the surface of that liquid, mixed with a little curd and serum. When churn- ed, butter is obtained. Heat separates the oily part, but injures its flavour.* CREAM OF TARTAR. See ACID (TAR- TARIC). * CRICHTONITE. A mineral so called in honour of Dr. Crichton, physician to the Emperor of Russia, an eminent mineralo- gist. It has a velvet-black colour, and crys- tallizes in very acute small rhomboids. Lustre splendent, inclining to metallic; fracture conchoidal; opaque; scratches fluor spar, but not glass. Infusible before CRU CRY the blow-pipe. It occurs in primitive rocks along- with octahedrite. Professor Jame- son thinks it may probably be a new spe- cies of titanium-ore.* CROCUS. The yellow or saffron-colour- ed oxides or iron and copper were former- ly called crocus martis and crocus veneris. That of iron is still called crocus simply, by the workers in metal who use it. * CROSS-STONE. Harmotome, or pyra- midal zeolite. Its colour is grayish-white, passing into smoke-gray, sometimes mas- sive, 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, intersecting each other, in such a manner that a common axis and acumi nation are formed, and the broad- er lateral planes make four re-entering an- gles. The crystals are not large. The surface of the smaller lateral planes is double-plumosely streaked. Lustre glis- tening, between vitreous and pearly. Of the cleavage, 2 folia are oblique, and 1 pa- rallel to the axis. Fracture perfect con- choidal. Translucent and semi-transparent. Harder than fluor spar, but not so hard as apatite. Easily frangible. Sp. gr. 2.35. It. fuses with intumescence and phosphores- cence, into a colourless glass. Its consti- tuents are 49 silica, 16 alumina, 18 bary- tes, and 15 water, by Klaproth. It has hitherto been found only in mineral veins and agate-balls. It occurs at Andreasberg in the Hartz, at Kongsberg in Norway, at Oberstein, Strontian in Argyllshire, and also near Old Kilpatrick in Scotland. Jameson* * CROTON ELEUTHERIA. Cascarilla bark. The following is Trommsdorf's ana- lysis of this substance, characterized by its emitting the smell of musk when burn- ed. Mucilage and bitter principle 864 parts, resin 688, volatile matter 72, water 48, woody fibres 3024; in 4696 parts.* * CRUSTS, the bony coverings of crabs, lobsters, &c. 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 composition; but the animal matter is in smaller quantity. By Merat-Guillot, 100 parts of lobster crust, consist of 60 carbonate of lime, 14 phos- phate of lime, and 26 cartilaginous matter. 100 of hen's egg-shells, consist of 89.6 car- bonate of lime, 5.7 phosphate of lime, 4.7 animal matter.* * CRYOLITE. A mineral which occurs massive, disseminated, and in thick lamel- lar concretions. Its colours are white and yellowish-brown. Lustre vitreous, inclin- ing 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. Before the blow -pipe, it be- comes first very liquid, and then assumes a slaggy appearance. It consists, by Klap- roth, of 24 alumina, 36 soda, and 40 fluoric acid and water. It is therefore a soda- fluate of alumina. If we regard it as com- posed 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 22.6 2 do. water, 2.25 18.5 12.15 100.00 Vauquelin's analysis of the same miner- al gives 47 acid and water, 32 soda, and 21 alumina. This curious and rare mineral has hitherto been found only in West Green- land, at the arm of the sea named Arksut, 30 leagues from the colony of Juliana Hope. It occurs in gneiss. Mr. Allan of Edin- burgh 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 indefatigable mineralo- gist M. Gieseke.* * CRYOPHORUS. The frost-bearer or carrier of cold, an elegant instrument in- vented 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 tempera- ture of 62, and if one grain of this were converted into vapour by absorbing 960, 960 then the whole quantity would lose 32 = 30, and thus be reduced to the tem- perature of 32. If from the 31 grains which still remain in the state of water, four grains more were converted into va- pour by absorbing 960, then the remain, ing 27 grains must have lost ^y of 960* = 142, which is rather more than suffi- cient 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 tempera ture, expands to 1800 times its former bulk* CRY CRY 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 5X1800=9000 grains of water. But let a glass tube be taken, having its internal diameter about one- eighth of an inch, with a ball at each ex- tremity 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 produ- ced by this condensation gives opportunity for a fresh quantity to arise from the oppo- site 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 fre- quently arrange their ultimate particles, so as to form regular polyhedral figures, or geometrical solids, to which the name of crystals has been given. Most of the so- lids which compose the mineral crust of the earth, are found in the crystallized state. Thus granite consists of crystals of quartz, feldspar, and mica. Even moun- tain masses like clay-slate, have a regular tabulated form. Perfect mobility among the corpuscles is essential to crystalliza- tion. 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 ab- stracted by evaporation in the latter, the attractive forces resume the ascendancy, and arrange the particles in symmetrical forms. Mere approximation of the parti- cles, however, is not alone sufficient for crystallization. A hot saturated saline so- lution, when screened, from all agitation, will contract by cooling into a volume much smaller, tliMi what it occupies in the solid state, without crystallizing. 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 re\ersion of the poles may be ef- fected, 1st, By contact of any part of the fluid, with a point of a solid, of similar composition previously formed. 2il, Vi- bratory motions, communicated 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 bal- ance 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 as- sume, when they are placed on a vibrating plane, in the neighbourhood of electrized or magnetized bodies. 3d, Negative or resinous voltaic electricity instantly deter- mines the crystalline arrangement, while positive voltaic electricity counteracts it. On this subject, I beg to refer the reader to an experimental paper, which I publish- ed 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 re -dissolves in gloomy weather. It might be imagined, that the same bo- dy 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 frequently the same chemical substance, crystallized in forms apparently very dissimilar. Thus, carbonate of lime assumes the form of a rhomboid, of a regular hexahedral prism, of a solid terminated by 12 scalene trian- gles, or of a dodecahedron with pentago- nal faces, &c. Bisulphuret of iron or mar- tial pyrites produces sometimes cubes and sometimes regular octohedrons, at one time dodecahedrons with pentagonal faces, at another icosahedrons with triangular faces, &c. While one and the same substance lends itself to so many transformations, we meet with very different substances, which pre- sent absolutely the same form. Thus fluate of lime, muriate of soda, sulphurer. of iron, sulphuret of lead, &c. crystallize in cubes, under certain circumstances; and in other cases, the same minerals, as well as sulphate of alumina and the diamond, assume the form of a regular octohedron. Rome de 1'Isle first referred the study of crystallization, to principles conforma- ble to observation. He arranged together, as far as possible, crystals of the same na- ture. Among the different forms relative to each species, he chose one as the most proper, from its simplicity, 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 polyhedrons, CRY CRY which seemed to be still further removed from it. To the descriptions and figures which he gave of the crystalline forms, he added the results of the mechanical mea- surement of their principal angles, and showed that these angles were constant in each variety. The illustrious Bergmann, by endeavour- ing to penetrate to the mechanism of the structure of crystals, considered the differ- ent forms relative to one and the same sub- stance, as produced by a superposition of planes, sometimes constant and sometimes variable, and decreasing around one and the same primitive form. He applied this primary idea to a small number of crystal- line forms, and verified it with respect to a variety of calcareous spar$ by fractures, which enabled him to ascertain the posi- tion of the nucleus, or of the primitive form, and the successive order of the la- minze covering this nucleus. Bergmann, however, stopped here, and did not trou- ble 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 mas- ter who so successfully filled up the out- lines of chemistry. In the researches which M. Haiiy under- took, about the same period, on the struc- ture of crystals, he proposed combining the form and dimensions of integrant mo- lecules with simple and regular laws of ar- rangement, and submitting these laws to calculation. This work produced a ma- thematical theory, which he reduced to analytical formulae, representing every pos- sible 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 may be assumed by a mineral substance, of which the rest may be re- garded as being modifications only, has frequently suggested itself to various phi- losophers, 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 invariable while we operate upon the same substance, however diversified or dis- similar the forms of the crystals belonging to this substance may be. Two or three examples will serve to place this truth in its proper light. Take a regular hexahedral prism of car- bonate of lime (PI. XIII. figs 1 and 2). This is what has been called dent de tochon, but which M. Haiiy calls metastatic. 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 alter- nately 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 chuse.not the edges l'j', c' d' b' m t which correspond with the preceding-, but the intermediate edges o o (fig. 2.) uncovered by the first sections, is very sensibly inclined from the same quantity, as well upon the resi- due p p d e b m of the base, as upon the residue o o J r l r of the adjacent plane. Set- ting out from this equality of inclinations, we deduce from it, by calculation, the va- CRY CRY 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 suc- ceed in extracting- 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' sul- phate of barytes will be a straight prism with rhombous bases; that of the crystals of phosphate of lime, a regular hexahedral prism? that of sulphuretted lead, a cube, &c.; and each of these forms will be con- stant 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 crys- tals, M. Haiiy calls secondary forms, such varieties as differ from the primitive form. In certain species, crystallization also produces this last form immediately. We may define the primitive form, a so- lid of a constant form, engaged symmetri- cally in all the crystals of one and the same species, and the faces of which follow the directions of the laminae which form these crystals. The primitive forms hitherto observed, are reduced to six, viz. the parallelopipe- don, the octohedron, the tetrahedron, the regular hexahedral prism, the dodecahe- dron with rhombous planes, all equal and similar, and the dodecahedron with trian- gular planes, composed of two straight py- ramids joined base to base. Forms of integrant Molecules. The nu- cleus of a crystal is not the last term of of its mechanical division. It may always be subdivided parallel to its different faces, and sometimes in other directions also. The whole of the surrounding substance is capable of being divided by strokes pa- rallel to those which take place with re- spect 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 mole- cule will be similar to this nucleus itself. But it may happen that the parallelopipe- don admits of further sections in other di- rections than the former. We may reduce the forms of the inte- grant molecules of all crystals to three, which are, the tetrahedron, or the simplest of the pyramids; the triangular prism, or the simplest of all the prisms; and the pa- lue of the angles with the precision of mi- nutes and seconds, which mechanical mea- surements are not capable of attaining. rallelopipedon, or the simplest among the solids, which have their faces parallel two and two. And since four planes at least are necessary for circumscribing a space, it is evident that the three forms in ques- tion, in which the number of faces is suc- cessively 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 these regular kinds of envelopes, which disguise one and the same primitive form in so many different ways. Now, observation shows, that this sur- rounding matter is an assemblage of lami- nae, which, setting out from the primitive form, decrease in extent, both on all sides at once, and sometimes in certain particu- lar parts only. This decrement i effected by regular subtractions of one jr more rows of integrant molecules; and the the- ory, 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 dis- coveries, indicating forms which, being still hypothetical only, may one day be present- ed to the inquiries of the philosopher. Decrements on the Edges. Let s s f (fig. 6. PI. XIII.) be a dodecahedron with rhom- bic planes. This solid, which is one of the six primitive forms of crystals, also pre- sents itself occasionally as a secondary form, and in this case it has as a nucleus, sometimes a cube, and sometimes an octo- hedron. Supposing the nucleus to be a cube: In order to extract this nucleus, it is sufficient successively to remove the six solid angles composed of four planes, such as , r, t, &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', 1 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 la- minae solely composed of cubic molecules, and that every one of these laminae exceeds the succeeding one, towards its four edges, by a quantity equal to one course of these same molecules. Afterwards we shall de- signate the decreasing laminae which enve- lope the mucleus, by the name of lamina of superposition. Now, it is easy to con- ceive that the different series will produce six quadrangular pyramids, similar in some respects to the quadrangular steps of a co- lumn, which will rest on the faces of the cube. Three of these pyramids are repre- sented in fig. 8. and have their summits in s, t t r'. Now, as there are six quadrangular py- CRY CRY ramids, we shall therefore have twenty -four triangles; such as O I, O * I, &c. But because the decrement is uniform from s to t y 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 therefore 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 re- spect to the crystals called boracic spars. The dodecahedron now under conside- ration, is represented by fig. 8. in such a way that the progress of the decrement may be perceived by the eye. On examin- ing 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 superposition, the last of which is reduced to a simple cube, whose edges determine the numbers of molecules which form the series 15, 13, 11, 9, 7, 5, 3, 1, the differ- ence being 2, because there is one course subtracted from each extremity. Now, if instead of this coarse kind of masonry, which lias the advantage of speak- ing to the eye, we substitute in our ima- gination the infinitely delicate architecture of nature, we must conceive the nucleus as being composed of an incomparably greater number of imperceptible cubes. In this case, the number of laminae of su- perposition will also be beyond comparison greater than on the preceding hypothesis. By a necessary consequence, the furrows which form these laminae by the alternate projecting and re-entering of their edges, will not be cognizable by our senses; and this is what takes place in the polyhedra which crystallization has produced at lei- sure, without being disturbed in its pro- gress. M. Huiiy 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, Sec. courses, is in the way of breadth. Decrements in height are those in which each lamina, exceeding only the following one by a single course in the direction of the breadth, may have a height double, triple, quadruple, Stc. to that of a molecule: this is expressed by saying that the decrement takes place by two courses, three courses, &c. in height. 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 So- ciety, and published 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 oc- tohedron, and no one in which a corres- ponding difficulty has occurred wi h re- gard to determining which modification of its form is to be considered as primitive; since in all these substances the tetrahe- dron appears to have equal claim to be re- ceived as the original from which all their 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 crystallo- graphy, by assuming the tetrahedron as primitive, for this may immediately be converted into an octohedron by the re- moval of four smaller tetrahedrons from its solid angles. (Plate XIV. fig. 1.) The substance which most readily admits of division by fracture into these forms, is fluor spar; and there is no difficulty in ob- taining a sufficient quantity for such expe- riments. But it is not, in fact, either the tetrahedron or the octohedron, which first presents itself as the apparent primitive form obtained by fracture. If we form a plate of uniform thickness by two successive divisions of the spar, pa- rallel 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 superficial angles 60 and 120 and presenting an appearance of primitive molecule, from which all the other modifications of such crystals might very simply be derived. And we find, moreover, that the whole mass of fiuor 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 re- presented fig. 2.) may be again split by na- tural fractures at right angles to its axis (fig. 3.), so that a regular tetrahedron may be detached from each extremity, while the remaining portion assumes the form of a regular octohedron; and since every rhom- boid that can be obtained, must admit of the same division into one octohedron and two* tetrahedrons, the rhomboid can no longer be regarded as the primitive form; and since the parts into which it is divi- sible 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 leav- ing vacuities, there is a difficulty in con- ceiving any arrangement in which the par- CRY tides will remain at rest: for, whether we suppose, with the Abbe Haliy, that the par- ticles are tetrahedral with octohedral cavi- ties, or, on the contrary, octohedral parti- cles 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 per- manent crystal. With respect to fluor spar and such other substances as assume the octohedral and tetrahedral forms, all difficulty is removed, says Dr. Wollaston, by supposing the ele- mentary particles to be perfect spheres, which, by mutual attraction, have assum- ed that arrangement 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 tri- angles with each other (as represented perspectively in fig. 4.), is familiar to every one; and it is evident that, if balls so plac- ed were cemented together, and the stra- tum 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 evi- dent 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 tetrahe- dron, having all its equilateral triangles. The construction of an octahedron, 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, iind 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, fig. 6. There is one observation with regard to these forms that will appear paradoxical, namely that a structure, which, in this case, was begun upon a square foundation, is really intrinsically the same as that which is begun upon the triangular basis. But if we lay the octohedral group, which con- sists 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 si- tuated precisely as they would be found in two adjacent strata of the triangular ar- rangement. Hence, in this position, we CRY may readily convert the octohedron into a regular tetrahedron, by addition of four more balls (fig. ?.). 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 by addition of three more balls, regularly disposed around it, the entire group of ten balls will then be found to represent a regular tetrahedron. For the purpose of representing the acute rhomboid, two balls must be appli- ed at opposite sides of the smallest octo- hedral 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 com- plete tetrahedral group may be removed from each extremity, leaving a central oc- tohedron, as may be seen in fig. 11. which corresponds to fig. 3. We have seen, that by due application of spheres to each other, all the most sim- ple forms of one species of crystal will be produced, and it is needless to pursue any other modifications of the same form, which must result from a series of decre- ments 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 difficult questions in crystallography, we are naturally led to inquire what forms would probably occur from the union of othersolids most nearly allied to the sphere. And it will appear that by the supposition of elementary particles that are spheroidi- cal, 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 speroid to be its shortest dimension, a class of solids will be formed which are nu- merous in crystallography. Jt has been re- marked above, that by the natural group- ing of spherical particles, fig. 10. one re- suiting solid is an acute rhomboid, similar to that of fig. 2. having certain determin- ate angles, and its greatest dimension in the direction of its axis. Now, if other particles having the same relative arrange- ment be supposed to have the form of ob- late spheroids, the resulting solid, fig. 12. will still be a regular rhomboid; but the measures 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 primitive form, may, in fact, con- sist of oblate spheroids as elementary par- ticles. Hexagonal Prisms. If our elementary spheroid be on the CRY CRY contrary 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 1 . 13.). The manifest consequence of this structure would be, that a solid so formed would be liable to split into plates at rig-lit ang-les to the axes, and the plutes would divide into prisms of three or six sides with all their angles equal, as occurs in phosphate of lime, beryl, &c. It may farther be observed, that the proportion of the height to the base of such a prism, must depend on the ratio between the axes of the elementary sphe- roid. 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, represented by black and white balls; and let it be required that, in their perfect intermixture, every black ball shall be equally distant from all surround- ing white balls, and that all adjacent balls of the same denomination shall also be equidistant from each other. The Doctor shows, that these conditions will be fulfil- led, if the arrangement be cubical, and that the particles will be in equilibria. Fig. 14. represents a cube so constituted of balls, alternately black and white through- out. The four black balls are 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 dissi- milar 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 correct representative of the entire mass, that would be compo- sed of equal and similar cubes. There remains one observation with re- gard to the spherical form of elementary particles, whether actual or virtual, that must be regarded as favourable to the fore- going hypothesis, namely, that many of those substances, which we have most rea- son to think simple bodies, as among the class of metals, exhibit this further evi- dence of their simple nature, that they crystallize in the octohedral form, as they would do if their particles were spherical. I But it must, on the contrary, be acknow- ledged, that we can at present assign no reason why the same appearance of simpli- city should take place in fluor spar, which is presumed to contain at least two ele- ments; and it is evident that any attempts to trace a general correspondence between VOL. I. the crystallographical and supposed die. mical elements of bodies, must in the present state of these sciences, be prema- ture. Any sphere when not compressed will be surrounded by twelve others, and, con- sequently, by a slight degree of compres- sion, will be converted into a dodecahe- dron, according to the most probable hy- pothesis 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. Carangeau, used by M. Haiiy, con- sists of two parallel blades, jointed like those of scissars, and capable of being ap- plied to a graduated semicircular sector, which gives the angle to which the joint is opened, in consequence of the previous apposition of the two blades to the angle of the crystal. 2. The reflective goniome- ter of Dr. Wollaston, an admirable inven- tion, which measures the angles of the minutest possible crystals with the utmost precision. An account of this beautiful in- strument may be found in the Phil. Trans, for 1809, and in Tilloch's Magazine for February 1810, vol. 35. Mr. William Phil- lips published, in the 2d volume of the Geological Transactions, an elaborate se- ries 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. Clarke got from the island Jean Mayen, in the Greenland seas. " Having there- fore," 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 reflecting- goniometer. A dou- ble image was reflected by one of the planes of the crystal, but the image re- flected by the contiguous plane was clear and perfectlv perceptible, by which I was enabled to measure the angle of inclina- tion; and after repeating the observation several times, I found it equal to 92 or 92|. Hence it is evident that these crys- tals are not zircons, although they possess a degree of lustre quite equal to that of zircon. In this uncertainty, 1 sent a small portion of the sand to Dr. Wollaston, and requested that he would himself measure tbeonffeof the particles exhibiting splen- dant 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 similar to that of Bolsenna in Italy." Such a ready means of minute research forms a delightful aid to the chemical philosopher, as well as the mineralogist. M. Haiiy, by a too rij^id adherence to the principle of 44 CRY CRY geometrical simplicity, obtained an erro- carbonates of lime the same angle as to neous determination of the angles in the the simple carbonate, the error became primary form of carbonate of lime, amount- still greater, as will appear from the follow- ing to 36 minutes of a degree. And by as- ing comparative measurements, signing to the magnesian and ferriferous Observed angle by Dr. Wollaston's goniometer. Carbonate of lime, 105 5' Magnesian carbonate, 106 15' Ferriferous carbonate, 10? (/ M . Haiiy will no doubt accommodate his results to these indications of Dr. Wollas- ton's goniometer, and give his theory all the perfection which its scientific value and elegance deserve. M. Beudant has lately made many ex- periments to discover, why a saline prin- ciple of a certain kind sometimes im- presses its crystalline 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 astonishing number of secondary forms, as we sometimes 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 ammo- niac, which crystallizes in pure water in octohedrons, by means of urea crystallizes in cubes. A very slight excess or defi- ciency of base in alum, causes it to assume either cubical or octohedral secondary forms; and these forms are so truly se- condary, that an octohedral crystal of alum, immerged in a solution which is richer in respect to its basis, becomes en- veloped 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 modify 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 under- go any variations, but those which may re- sult from the chemical action of the sub- stance forming the deposite. Common salt crystallized in a solution of borax, ac- quires 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 crystal- lization 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 portion of acetate of cop- Theoretic angle. 104 28' 40" 104 28' 40" 104 28' 40" Error. 36' 20" 1 46' 20" 2 31' 20" per reduces sulphate of iron to the same simple rhomboidal form, notwithstanding that this form is disposed to become com- plicated with additional surfaces. Sulphate of alumina brings sulphate of iron to a rhomboid, with the lateral angles only truncated, or what M. Haiiy calls his va- riett unitaire; 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 substances, 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 chlo- rite, is reduced to its primitive form; while the other end, which is pure, is va- ried by many facets produced by different decrements. In a mingled solution of two or more salts, of nearly equal solubility, the crys- tallization of one of them may be some- times determined, by laying or suspending in the liquid, a crystal of that particular salt. M. Le Blanc states, that on putting in- to a tall and narrow cylinder, crystals at different heights, in the midst of their sa- turated 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 continue to en- large, while those at the surface diminish and dissolve. Those salts which are apt to give up their water of crystallization to the atmos- phere, and of course become efflorescent, may be preserved by immersion in oil, and subsequent wiping of their surface. In the Wernerian language of crystalli- zation, 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 re- place by a kind of bevel, an angle, or an edge, is called a beveltnent. When these new faces are to the number of three or CRY CUR more, they produce what Werner termed a pointing, or acumination. When two faces unite by an edge in the manner of a roof, they have been called culmination. Keplacc- ment is occasionally used for bevelment. The reader will find some curious ob- servations on crystallization, by Mr. J. F. Daniell, in the 1st volume of the Journal of Science. Professor Mohs, successor to Werner in Freyberg, Dr. Weiss, professor of miner- alogy, in Berlin, and M. Brochant, profes- sor of mineralogy in Paris, have each re- cently published systems of mineralogy. Pretty copious details, relative to the first, are given in the 3d volume of the Edin- burgh Philosophical Journal.* In a paper in the Journal de Physique, M. Le Blanc gives instructions for obtain- ing crystals of large size. His method is to employ 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 vessels with more of the mo- ther-water of a solution that has been brought to crystallize confusedly: 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 sur- face of the metal has begun to congeal. The same effect may be observed if the metal be poured into a plate or dish, a lit- tle inclined, which is to be suddenly inclin- ed 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 crystals. The operation of crystallizing, or crys- tallization, is of great utility in the purify- ing 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 likewise in the quantity of salt capable of being suspended in a given quantity of water, they differ greatly from each other. It is therefore practica- ble in general to separate salts by due man- agement 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, eva- poration may be proceeded upon as before. This manipulation depends upon the diffe- rent properties of the two salts with regard to their solubility and crystallization in like circumstances. For nitre is considerably more soluble in hot than in cold water, while common salt is scarcely more soluble in the one case than in the other. The com- mon salt consequently separates in crystals as the evaporation 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. *CITBE ORE. Hexahedral Olivenite. Wur- felerz. Wern. This mineral has a pistacio- green colour, of various shades. It occurs massive, and crystallized in the perfect cube; in a cube with four diagonally op- posite angles truncated; or in one trun- cated 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-yel- low. Harder than gypsum. Easily fran- gible. Sp. gr. 3.0. Fuses with disengage- ment of arsenical vapours. Its constitu- ents 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 48 iron, 18 arsenic acid, 2 to 3 carbonate of lime, and 32 wa- ter. It is found in veins, accompanied with iron-shot quartz, in Tincroft and va- rious 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 ar- senic. Jameson* CUPEL. A shallow earthen vessel, some- what resembling a cup, from which it de- rives its name. It is made of phosphate of lime, or the residue of burned bones ram- med 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. CUPEL LATION. 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, oi* other substances. See MILK. DAT DEC CYANITE, or KYANITE. Disthene of Haiiy. Its principal colour is Berlin-blue, which passes into gray and green. It oc- curs massive and disseminated, also in dis- tinct concretions. The primitive form of its crystals is an oblique four-sided prism; and the secondary forms are, an oblique four- sided prism, truncated on the lateral edges, and a twin crystal. The planes are streak- ed, splendent, and pearly. Cleavage three- fold. Translucent or transparent. Surface of the broader lateral planes as harik as apatite; that of the angles, as quartz. Ea- sily frangible. Sp. gr. 3.5. When pure it is idio-electric. Some crystals by friction ac- quire negative, others positive electricity; hence Haiiy's name. It is infusible before the blow-pipe. It consists, by Klaproth, of 43 silica, 55.5 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 Banftshire; at Airolo on St. Gothard, and in various countries of Europe, as well as in Asia and America. It is cut and polished in India as an infe- rior sort of sapphire. Jameson.* * CYANOGEN. The compound base of prussic acid. See PRUSSINE.* * CYMOPHANE of Haiiy. The CHRYSO- BERYJL..* D nAMPS. The permanently elastic fluids which are extricated in mines, and re destructive to animal life, are called damps by the miners. The chief distinc- tions made by the miners, are choak-damp, which extinguishes their candles, hovers about the bottom of the mine, and consists for the most part of carbonic acid gas; and fire-damp, or hydrogen gas, which occupies the superior spaces, and does great mis- chief by exploding whenever it comes in contact with their lights. See GAS, COM- BUSTION, & LAMP. * DAOURITE. A variety of red schorl from Siberia.* * DAPHNIN. The bitter principle of Daphne stlpina, discovered by M. Vauque- lin. From the alcoholic infusion of this bark, the resin was separated by its con- centration. On diluting the tincture with water, filtering, and adding acetate of lead, a yellow dap/mate of lead fell, from which sulphuretted hydrogen separated the lead, and left the daphnin in small transparent crystals. They are hard, of a grayish co- lour, 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 precipita- ted by acetate of lead; yet acetate of lead is employed in the first process to throw 7 it down.* * DATOLITE. Datholit of Werner. This species is divided into two sub-species, viz. Common Datolite, and Botrioidal Datolite. 1. Common Datolite. Colour white of various shades, and greenish -gray, inclin- ing to celadine-grecn. It occurs in large coarse, and small granular distinct concre- tions, and crystallized. Primitive form, an oblique four-sided prism of 109 28' and 70 3'. The principal secondary forms, are the low oblique four-sided prism, and the rectangular four-sided prism, flatly acuminated on the extremities, with four planes which are set on the lateral planes. The crystals are small and in druses. Lus- tre shining and resinous. Cleavage imper- fect, 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 co- loured 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 man- ganese. It is associated with large folia- ted granular calcareous spar, at the mine of Nodebroe, near Arcndal in Norway. It re- sembles prehnite, but is distinguished by its resinous lustre, compact fracture, infe- rior hardness, and not becoming electric by heating. Jameso?).* * 2. BOTRIOIDAL DATOLITE. SceBoT- RYOLITE.* * DATURA. A vegeto-alkali obtained from DATURA STRAMONIUM.* * DEAD-SEA WATER. Sec WATER.* DECANTATION. The action of pouring* oft' the clearer part of a fluid by gently in- clining 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 vegetables, 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 probable frtim the operations we arfe BEL DEL acquainted with, that it seldom takes place but in consequence of some combination or composition having been effected. Tt 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 sud- denly heated, accompanied by a violent ex- foliation of their particles. This pheno- menon has been ascribed by Dr. Thomson, and other chemical compilers, to the " sud- den 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 evidence of the falseness of the explanation; for abso- lutely dry sulphate of barytes decrepitates furiously, without any possible formation of steam, or any loss of weight. The same thing 1 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 decrepitate 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 heat- ed; namely, from the unequal expansion of the laminae which compose them, in conse- quence of their being imperfect conduc- tors of heat. The true cleavage of mine- rals may often be detected in this way, for they fly asunder at their natural fissures.* j- DEFLAGRATION. This word is used by electricians and chemists, to denote that kind of combustion, which takes place in metallic wires, or leaves, when subject- ed to galvanic or electric discharges. See GALVANIC DEFLAGRATCR^ * 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 quanti- ty of distilled water, and then pressed in a cloth. The decoction is to be filtered, and boiled for a few minutes with pure mag- nesia. It must then be re-filtered, and the residuum left on the filter is to be well washed, and then boiled with highly recti- fied alcohol, which dissolves out the alkali. By evaporation, a whiu pulverulent sub- stance, presenting a few crystalline points, is obtained. It may also be procured by the action of dilute sulphuric acid, on the bruised but unshelled seeds. The solution of sulphate thus formed, is precipitated by subcarbo- nate of potash. Alcohol separates from this precipitate the vegetable alkali in an impure state Pure delphinia obtained by the first pro- cess, is crystalline while wet, but becomes opaque on exposure to air. Its taste is bit- ter 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 and ether dissolve it very readily. The alco- holic solution renders sirup of violets green, and restores the blue tint of litmus reddened by an acid. It forms soluble neutral salts with acids. Alkalis precipi- tate the delphinia in a white gelatinous state, like alumina. Sulphate of delphinia evaporates in the air, does 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 be- comes converted into a yellow matter, little soluble in water, but soluble in boiling al- cohol. This solution is bitter, is not pre- cipitated by potash, ammonia, or lime-wa- ter, and appears to contain no nitric acid, though itself is not alkaline. It is not de- stroyed 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 crys- tallize, 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 exists in the seeds of the stavesacre, in com- bination with malic acid, and associated with the following principles: 1. A brown bitter principle, precipitable by acetate of lead. 2. Volatile oil. 3. Fixed oil. 4. Albu- men. 5. Animalized matter. 6. Mucus. 7. Saccharine murus. 8. Yellow bitter princi- ple, not precipivabie by acetate of lead. 9. Mineral salts. Jlnnales de Chimie et Phg- sique, vol. xii. p. f,58 * DELIQUESCENCE. The spontaneous as- sumption of the fluid state by certain sa- line substances, when left exposed to the air, in consequence of the water they attract from it. DEW DEW DEPHLEGMATION. Any method by Which bodies are deprived of water. DEPHLOGISTICATED. A term of theold chemistry, implying deprived ofphlogiston, or the inflammable principle, and nearly synonymous with what is now expressed by oxygenated, or oxidized. DEPHLOGISTICATED AIR. The same with oxygen gas. DERBYSHIRE SPAR. A combination of calcareous earth with a peculiar acid called the FLUORIC, which see. Wells shows that very little is ever depo- sited in opposite circumstances; and that little only when the clouds are very high. It is never seen on nights both cloudy and windy; and if in the course of the night the weather, from being serene, should become dark and stormy, dew which had been de- posited will disappear. In calm weather, if the sky be partially covered with clouds, more dew will appear than if it were en- tirely uncovered. Dew probably begins in the country to * DESICCATION is most elegantly accom- appear upon grass, in places shaded from plished, by means of the air-pump and sul- the sun, during clear and calm weather, phuric acid, as is explained under CONGE- soon after the heat of the atmosphere has LATION * declined, and continues to be deposited DESTRUCTIVE DISTILLATION. When through the whole night, and for a little organized substances, or their products, after sunrise. Its quantity will depend in, are exposed to distillation, until the whole some measure on the proportion of mois- has suffered all that the furnace can effect, ture in the atmosphere, and is consequently greater after rain than after a long- tract of dry weather; and in Europe, with southerly and westerly winds, than with those which blow from the north and the east. The di- rection of the sea determines this relation, of the winds to dew. For in Egypt, dew is scarcely ever observed except while the northerly or Etesian winds prevail. Hence also, dew is generally more abundant in spring and autumn, than in summer. And it is always very copious on those clear nights which are followed by misty morn- ings, which show the air to be loaded with son. The first stated, in the Phil. Trans, for moisture. Arid a clear morning, following a 1771, that on a winter night, during which cloudy night, determines a plentiful depo- the atmosphere was several times misty and sition of the retained vapour. When warmth clear alternately, he observed a thermome- of atmosphere is compatible with clearness, ter, suspended in the air, always to rise from as is the case in southern latitudes, though a half to a whole degree, whenever the for- mer state began, and to fall as much as soon as the weather became serene. the process is called destructive distilla- tion. DETONATION. A sudden combustion and explosion. See COMBUSTION, FULMI- NATING i'o \VDEHS, and GUNPOWDER. * DEW. The moisture insensibly depo- sited from the atmosphere on the surface of the earth. The first facts which could lead to the just explanation of this interesting, and, till very lately, inexplicable natural phenome- non, are due to the late Mr. A. Wilson, professor of astronomy in Glasgow, and his Dr. Patrick Wilson communicated, in 1786, to the Royal Society of Edinburgh, a valuable paper on hoar-frost, which was published in the first volume of their Transactions. It is replete with new and valuable obser- vations, whose minute accuracy subsequent experience has confirmed. Dr. Wilson had previously, in 1781, described the surface of snow, during a clear and calm night, to be 16 colder than air 2 feet above it; and in the above paper he shows, that the depo- sition of dew and hoar-frost is uniformly accompanied with the production of cold- He was the first among philosophical ob- servers who noticed this conjunction. But the different force with which different sur- faces project or radiate heat being then un- known, Dr. Wilson could not trace the phe- nomena of dew up to their ultimate source. This important contribution to science has been lately made by Dr. Wells, in his very ingenious and masterly essay on dew. 1. Phenomena of De-w. Aristotle justly remarked, that dew ap- pears only on calm and clear nights. Dr. seldom in our country, the dew becomes much more copious, because the air then contains more moisture. Dew continues to form with increased copiousness as the night advances, from the increased refri- geration of the ground. 2. On the cause of dew. Dew, according to Aristotle, is a species of rain, formed in the lower atmosphere, in consequence of its moisture being con- densed by the cold of the night into minute drops. Opinions of this kind, says Dr. Wells, are still entertained by many per- sons, among whom is the very ingenious Professor Leslie. (Relat. of Heat and Mois- ture, p. 37. and 132.) A fact, however, first taken notice of by Gerstin, who published his treatise on dew in 1773, proves them to be erroneous; for he found that bodies a little elevated in the air, often become moist with dew, while similar bodies, lying on the ground, remain dry, though neces- sarily, from their position, as liable to be wetted, by whatever falls from the heavens, as the former. The above notion is perfect- ly refuted, by what will presently appear relative to metallic surfaces exposed to the air in a horizontal position, which remain DEW DEW dry, while every thing around them is co- vered with dew. After a long period of drought, when the air was very still and the sky serene, Dr. Wells exposed to the sky, 28 minutes be- fore sunset, previously weighed parcels of wool and swandown, upon a smooth, un- painted, and perfectly dry fir table, 5 feet long, 3 broad, and nearly 3 in height, which had been placed an hour before, in the sun- shine, in a large level grass field. The wool, 12 minutes after sunset, was found to be 14 colder than the air, and to have ac- quired no weight. The swandown, the quantity of which was much greater than that of the wool, was at the same time 13 colder than the air, and was also without any additional weight. In 20 minutes more, the swandown was 14 colder than the neighbouring air, and was still without any increase of its weight. At the same time the grass was 15 colder than the air four feet above the ground. Dr. Wells, by a copious induction of facts derived from observation and experiment, establishes the proposition, that bodies be- come colder than the neighbouring air BE- FORE they are dewed. The cold therefore which Dr. Wilson and Mr. Six conjectured to be the effect of dew, now appears to be its cause. But what makes the terrestrial surface colder than the atmosphere? The radiation or projection of heat into free space. Now the researches of Professor Leslie and Count llumford have demonstra- ted, that different bodies project heat with very different degrees of force. In the operation of this principle, there- fore, conjoined with the power of a concave mirror of cloud or any other awning, to re- flect or throw down again those calorific emanations which would be dissipated in a clear sky, we shall find a solution of the most mysterious phenomena of dew. Two circumstances must here be considered: 1. The exposure of the particular surface to be dewed, to the free aspect of the sky. 2. The peculiar radiating power of the surface. 1. Whatever diminishes the view of the sky, as seen from the exposed body, obstructs the depression of its tempera- ture, and occasions the quantity of dew formed upon it, to be less than would have occurred, if the exposure to the sky had been complete. Dr. Wells bent a sheet of pasteboard into the shape of a penthouse, making the angle of flexure 90 degrees, and leaving both ends open. This was placed one evening with its ridge uppermost, upon a grass-plat in the direction of the wind, as well as this could be ascertained. He then laid 10 grains of white, and moderately fine wool, not artificially dried, on the middle part of that spot of the grass which was sheltered by the roof, and the same quantity on ano- ther part of the grass-plat, fully exposed to the sky. In the morning the sheltered wool was found to have Jtereased in weight only 2 grains, but that wiich had been exposed to the sky 16 grains. He varied the expe- riment on the same night, by placing up- right on the grass-plat a hollow cylinder of baked clay, 1 foot diameter, and 2 feet high. On the grass round the outer edge of the cylinder, were laid 10 grains of wool, which in this situation, as there was not the least wind, would have received as much rain, as a like quantity of wool, fully exposed to the sky. But the quantity of moisture acquired by the wool, partially screened by the cylinder from the aspect of the sky was only about 2 grains, while that acquired by the same quantity fully exposed, was 16 grains. Repose of a body seems necessary to its acquiring its utmost coolness, and a full deposite of dew. Gravel walks and pavements project heat, and ac- quire dew, less readily than a grassy sur- face. Hence wool placed on the former has its temperature less depressed than on the latter, and therefore is less bedewed. Nor does the wool here attract moisture by ca- pillary action on the grass, for the same ef- fect happens if it be placed in a saucer. Nor is it by hygrometric attraction, for in a cloudy night, wool placed on an elevated board acquired scarcely any increase of weight. If wool be insulated a few feet from the ground on a bad conductor of heat, as a board, it will become still colder than when in contact with the earth, and acquire fully more dew, than on the grass. At the wind- ward end of the board, it is less bedewed than at the sheltered end, because in the former case, its temperature is nearer to that of the atmosphere. Hough and porous surfaces, as shavings of wood, take more dew than smooth and solid wood; and raw silk and fine cotton are more powerful in this respect than even wool. Glass projects heat rapidly, and is as rapidly coated with dew. But bright metals attract dew much less powerfully than other bodies. If we coat a piece of glass, partially, with bright tin-foil, or silver leaf, the uncovered portion of the glass quickly becomes cold by radiation, on exposure to a clear nocturnal sky, and ac- quires moisture; which beginning on those parts most remote from the metal, gradu- ally approaches it. Thus also, if we coat outwardly a portion of a window pane with tin-foil, in a clear night, then moisture will be deposited inside, on every part except opposite to the metal. But if the metal be inside, then the glass under and beyond it will be sooner, or most copiously bedewed. In the first case, the tin-foil prevents the glass under it from dissipating its heat, and therefore it can receive no dew; in the second case, the tin-foil prevents the glass DEW DEW which it coats, from receiving the calorific influence of the apartment, and hence it is sooner refrigerated by.|external radiation, than the rest of the pane. Gold, silver, copper, and tin, bad radiators of heat, and excellent conductors, acquire dew with greater difficulty than platina, which is a niore imperfect conductor; or than lead, zinc, and steel, which are better radiators. Hence dew which has formed upon a metal will often disappear, while other substances in the neighbourhood retrain wet; and a metal purposely moistened, will become dry, while neighbouring bodies are acquiring moisture. This repulsion of dew is communicated by metals to bodies in contact with., or near them. Wool laid on metal acquires less dew, than wool laid on the contiguous grass. If the night becomes cloudy, after having been very clear, thoug-h there be no change with respect to calmness, a considerable alteration in the temperature of the grass always ensues. Upon one such night, the grass, after having been 12 colder than the air, became only 2 colder; the atmos- pheric temperature being the same at both observations. On a second night, grass be- came 9 warmer in the space of an hour and a half; on a third night, in less than 45 minutes, the temperature of the grass rose 15, while that of the neighbouring air in- creased only 3^. During a fourth night, the temperature of the grass at half past 9 o'clock was 32. In 20 minutes after- wards, it was found to be 39, the sky in the mean time having become cloudy. At the end of 20 minutes more, the sky clear, the temperature of the grass was again 32. A thermometer lying on a grass- plat, will sometimes rise several degrees, when a cloud comes to occupy the zenith of a clear sky. Wher, during a clear and still night, different thermometers, placed in different situations, were examined, at the same time, those which were situated where most dew was formed, were always found to be the lowest. On dewy nights the tem- perature of the earth, half an inch^or an inch beneath the surface, is always found much warmer than the grass upon it, or the air above it. The differences on five' such nights, were from 12 to 16 degrees. In making experiments with thermome- ters it is necessary to coat their bulbs with silver or gold leaf, otherwise their glassy surface indicates a lower temperature than that of the air, or the metallic plate it touches. Swandown seems to exhibit great- er cold, on exposure to the aspect of a clear sky, than any thing else. When grass is 14 below the atmospheric temperature, swanclown is commonly 15. Fresh un- broken straw and shreds of paper, rank in this respect with swandovvn. Charcoal, lampblack, and rust of iron, are also very productive of cold. Snow stands 4 or 5 higher than swanclown laid upon it in a clt- ar night. The following tabular view of observa- tions by Dr. Wells, is peculiarly instruc- tive: 6h. 45' 7k. 7h. 20' 7h. 40' 8A. 45' Heat of the air 4 feet above the grass, 603 60| Q 59 53" 54 wool on a raised board, - - 53 i 54 51$ 48 444 swandown on the same, - - 54 53 51 47^ 42:1 surface of the raised board, - 58 57 55i grass-plat, 53 51 49 49 42 The temperature always falls in clear nights, but the deposition of dew, depend- ing on the moisture of the air, may occur or not. Now, if cold were the effect of dew, the cold connected with dew ought to be always proportional to the quantity of that fluid; but this is contradicted by experience. On the other hand, if it be granted that dew is water precipitated from the atmosphere, by the cold of the body on which it appears, the same degree of cold in the precipitating body may be attended with much, with little, or with no dew, according to the existing state of the air in regard to moisture, all of which circumstances are found really to take place. The actual precipitation of dew, indeed, ought to evolve heat. A very few degrees of difference of t.crrr- perature between the grass and the atmos- phere is sufficient to determine the forma- tion of dew, when the air is in a proper state. But a difference of even 30, or more, sometimes exists, by the radiation of heat from the earth to the heavens. And hence, the air near the refrigerated sur- face must be colder than that somewhat elevated. Agreeably to Mr. Six's observa- tions, the atmosphere, at the height of 220 feet, is often, upon such nights, 10 warmer than what it is seven feet above the ground. And had not the lower air thus imparted some of its heat to the surface, the latter would have been probably 40 under the temperature of the air. Insulated bodies, or prominent points, are sooner covered with hoar-frost and dew others? teaiise tire equilibrium of DEW DEW tfceir temperature is more difficult to be restored. As ae'.-ial stillness is necessary to the cooling* effect of radiation, we can understand why the hurtful effects of cold, heavy fog's, and dews, occur chiefly in hol- low and cnniiiien places, and less frequently on hills In like manner, the leaves of trees often remain dry throughout the the night, while the blades of grass are covered with dew. No direct experiments can be made to ascertain the manner in which clouds pre- vent 6r lessen the appearance of a cold at night, upon the surface of the earth, greater than that of the atmosphere. But it may be concluded from the preceding observa- tions, that they produce this effect almost entirely by radiating- heat to the earth, in return for that which they intercept in its progress from the earth towards the hea- vens. The heat extricated by the conden- sation of transparent vapour into cloud must soon be dissipated; whereas, the ef- fect of greatly lessening- or preventing- al- together the appearance of a greater cold on the earth than that of the air, will be produced by a cloudy sky during- the whole of a long- night. We can thus explain, in a more satisfac- tory manner than has usually been done, the sudden warmth that is felt in winter, when a fleece of clouds supervenes in clear frosty weather. Chemists ascribed this sud- den and powerful change to the disengage- ment of the latent heat of the condensed vapours; but Dr. Wells's thermometric ob-- servalions on the sudden alternations of temperature by cloud and clearness, ren- der that opinion untenable. We find the atmosphere itself, indeed, at moderate ele- vations, of pretty uniform temperature, while bodies at the surface of the ground suffer great variations in their temperature. This single fact is fatal to the hypothesis derived from the doctrines of latent heat. " I had often," says Dr. Wells, " smiled, in the pride of half knowledge, at the means frequently employed by gardeners, to protect tender plants from cold, as it appeared to me impossible that a thin mat, or any such flimsv substance, could prevent them from attaining the temperature of the atmosphere, by which alone I thought them liable to be injured. But when 1 had learn- ed, that bodies on the surface of the earth become, during- a still and serene night, colder than the atmosphere, by radiating their heat to the heavens, 1 perceived im- mediately a just reason ibr the practice, which I had before deemed useless, lie- ing desirous, however, of acquiring- some precise information on this subject, 1 iixtd perpendicularlv, in the earth of a grass- pi it, four small sticks, and over their up- f,-i extrc'iuitics, which were tix inches VfK.. i. above the grass, and formed the corners of a square whose sides were two feet long, I drew tightly a very thin cambric handkerchief. In this disposition of things, therefore, nothing existed to prevent the free passage of air from the exposed grass to that which was sheltered, except the four small sticks, and there was no sub- stance to radiate downwards to the latter grass, except the cambric handkerchief.'* The sheltered grass, however, was found nearly of the same temperature as the air, while the unsheltered was 5 or more cold- er. One night the fully exposed grass was 11 colder than the air; but the sheltered grass was only 3 colder. Hence we se* the power of a very slight awning, to avert or lessen the injurious coldness of the ground. To have the full advantage of such protection from the chill aspect of the sky, the covering should not touch the subjacent bodies. Garden walls act partly on the same principle. Snow screens plants from this chilling radiation. In warm cli- mates, the deposition of dewy moisture on. animal substances hastens their putrefac- tion. As this is apt to happen only in clear nights, it was anciently supposed that bright moonshine favoured animal corruption. From this rapid emission of heat from, the surface of the ground, we can now ex- plain the formation of ice during the night in Bengal, while the temperature of the air is above 32. The nights most favourably for this effect, are those which are the calmest and most serene, and on which the air is so dry as to deposite little dew after midnight. Clouds and frequent changes of wind are certain preventives of conge- lation. 300 persons are employed in this operation at one place. The enclosures formed on the ground are four or five feet wide, and have walls only four inches high. In these enclosures, previously bedded with dry straw, broad, shallow, unglazed earthen pans are set, containing unboiled pump-wa- ter. Wind, which so greatly promotes eva- poration, prevents the freezing altogether, and dew forms in a greater or less degree during the whole of the nights most pro- ductive of ice. If evaporation were con- cerned in the congelation, wetting the straw would promote it. But Mr. Williams, in the 8.3d vol. of the Phil. Trans, says, that itb necasaury to the success of the process that the straw be drii. In proof of this lie mentions, that when the straw becomes wet by accident it is renewed; and that when he purposely wetted it in some of the in- closures, the formation of ice there was al- ways prevented. Moist straw both conducts heat and* raises vapour from the ground, so as to obstruct the congelation. According to Mi-. Leslie, water stands at the head of radiating substances, bee CA-u.ou.tv,.* DIA DIA * DIALLASS. A species of the genus Schil- ler spar, Diallage has a grass-green colour. It occurs massuve or disseminated. Lustre glistening and pearly. Cleavage imperfect double. Translucent. Harder than fluor spar. Brittle. Sp.gr. 31. It melts before the blow-pipe into a gray or greenish ena- mel. Its constituents are 50 silica, 11 alu- mina, 6 magnesia, 13 lime, 5.3 oxide of iron, 1.5 oxide of copper, 7'5 oxide of chrome. Vauquelin It occurs in the island of Corsi- ca, and in Mont Rosa in Switzerland, hlng with saussurite. It is the verde di Corsica duro of artists, by whom it is fashioned into ring-stones and snuff-boxes. It is the sma- ragdite of Saussure. The diallage in the rock is called gabbro.* * D'A.voxu. Colours white and gray, also red, brown, yellow, green, blue, and black. The two last are rare. When cut it exhi- bits a beautiful play of colours in the sunbeam. It occurs in rolled pieces, and also crystal- lized : 1st, In the octohedron, in which each pl-me is inclined to the i djacent, at an angle of 1U9 C 28' 16". The- faces are usually cur- v.lm.-ar. This is the fundamental figure. 2d, A simple three-sided pyramid, truncated on ail the angles. 3d, A segment, of the oc- tohedron. 4th, Twin Crystal 5th, Octohe- dron, with all the edges truncated. 6th, Octohedron, flatly bevelled on all the edges. 7th, Khornboidal dodecahedron. 8th, Octo- hedron with convex faces, in which each is divided into three triangular ones, forming altogether 24 faces. 9th, Octohedron, in which each convex face is divided into six planes, forming 48 in all. 10th, Rhomboi- dal dodecahedron, with diagonally broken planes, llth, A flat double three-sided py- ramid. I2rh, Very flat double three-sided pyramid, with cylindrical convex faces. 13th, Very flat double six-sided pyramid. 14th, Cube truncated on the edges. Crystal small. Surface rough, uneven, or streaked. Lustre splendent, and internally perfect adamantine. Cleavage octohedral, or parallel to the sides oi an octohedron. Foliated structure. Frag- ments octohedral or tetrahedral. Semi trans- pftrent. Refracts single. Scratches all known minerals. Rather easily frangible. Streak gray. Sp. gr. 3.4 to 3-6l It consists of pure carbon, as we shall presently demonstrate. When rubbed, whether in the rough or po- lished state, it shows positive electricity; whereas rough quartz affords negative. It becomes phosphorescent on exposure to the sun, or the electric spark, and shines with a fiery light. In its power of refracting light it is exceeded only by red lead-ore, and or- pimeut. It reflects all the light falling on its posterior surface at an angle of incidence greater than 24 13', whence its great lustre is urriv.-d. Artificial gerns reflect the half of this light. It occurs in imbedded grains and crystals in a sandstone in Brazil, which rests on chlorite and clay-slate. In India the diamond bed of clay is underneath beds of red or bluish -black clay; and also in allu- vial tracts both in India and Brazil. For the mode of working diamond mines, and cutting and polishing diamonds, consult Jameson's Mineralogy, vol. i. p. 11. The diamond is the most valued of all mi- nerals. Dr. Wollaston has explained the cutting principle of glaziers' diamonds, with his accustomed sagacity, in the Phil. Trans, for 1816. The weight, and consequently the value of diamonds, is estimated in carats, one of which is equal to four grains, and the price of one diamond, compared to that of another of equal colour, transparency, purity, form, &c. is as the squares of the respective weights. The average price of rough diamonds that are worth working, is about L. 2 for the first carat. The value of a cut diamond being equal to that of a rough diamond of double weight, exclusive of the price of workman- ship, the cost of a wrought diamond of 1 carat is 2 do. is 23 3 do. is 32 4 do is 42 L.8 X L.8, = 32 X L.8, = 72 X L.8, = 128 100 do. is 1002 x L.8, = 80000. This rule, however, is not extended t diamonds of more than 20 carats. The lar- ger ones are disposed of at prices inferior to their value by that computation. The snow- white diamond is most highly prized by the jeweller. If transparent and pure, it is said to be of the first water. The carat grain is different from the Troy grain. 156 carats make up the weight of one oz. troy; or 6 12 diamond grains are con- tained in the Troy ounce. From the high refractive power of the diamond, MM. Biot and Arago supposed that it might contain hydrogen. Sir H. Da- vy, from the action of potassium on it, and its non-conduction of electricity, suggested in his third Bakerian lecture that a minute portion of oxygen might exist in it; and in his new experiments on the fluoric com- pounds, he threw out the idea, that it might be the carbonaceous principle, combined with some new, light, and subtle element, of the oxygenous and chlorine class. This unrivalled chemist, during his resi- dence at Florence in March 1814, made several experiments on the combustion of the diamond and of plumbago by means of the great lens in the cabinet of natural his- tory, the same instrument as that employed in the first trials on the action of the solar heat on 'he diamond, instituted in 1694 by Cosmo III. Grand Duke of Tuscany. He subsequently made a series of researches on DIA DIG the combustion of different kinds of char. coal at Rome. His mode of investigation was peculiarly elegant, and led to the most decisive results. He found that diamond, when strongly ignited by the lens, in a thin capsule of pla- tinum, perforated with many orifices, so as to admit a free circulation of air, continued to burn with a steady brilliant red light, visible in the brightest sunshine, after it was with- drawn from the focus. Some time after the diamonds were removed out of the focus, indeed, a wire of platina that attached them to the tray was fused, though their weight was only 1.84 grains. His apparatus con- sisted of clear glass globes of the capacity of from 14 to 40 cubic inches, having single a- pertures to which stop-cocks were attached A small hollow cylinder of platinum was at- tached to one end of the stop-cock, and was mounted with the Iktle perforated capsule for containing the diamond. When the ex- periment was to be made, the globe con- taining the capsule and the substance to be burned was exhausted by an excellent air pump, and pure oxygen, from chlorate of potash, was then introduced. The change of volume in the gas after combustion was estimated by means of a fine tube connected with a stop-cock, adapted by a proper screw to the stop-cock of the globe, and the ab- sorption was judged of by the quantity of mercury that entered the tube, which af- forded a measure so exact, that no altera- tion however minute could be overlooked. He had previously satisfied himself that a quantity of moisture, less than l-100th of a grain, is rendered evident by deposition on a polished surface of glass ; for a piece of paper weighing one grain was introduced into a tube of about four cubic inches capa- city, whose exterior was slightly heated by a candle. A dew was immediately percep- tible on the inside of the glass, though the paper, when weighed in a balance turning with 1 100th of a grain, indicated no appre- ciable diminution. The diamonds were always heated to red- ness before they were introduced into the capsule. During their combustion, the glass globe was kept cool by the application of water to that part of it immediately above the capsule, and where the heat was great- est. From the results of his different experi- ments, conducted with the most unexcep- tionable precision, it is demonstrated, that diamond affords no other substance by its combustion than pure carbonic acid gas ; and that the process is merely a solution of diamond in oxygen, without any change in the volume of the gas. It likewise appears, that in the combustion of the different kinds of charcoal, water is produced ; and that from the diminution of the volume of the oxygen, there is every reason to bejievethat the water is formed by the combustion of hydrogen existing in strongly ignited char- coal. As the charcoal from oil of turpen- tine left no residuum, no other cause but the presence of hydrogen can be assigned for the diminution occasioned in the volume of the gas during its combustion. The only chemical difference perceptible between diamond and the purest charcoal is, that the last contains a minute portion of hydrogen ; but can a quantity of an element, less in some cases than 1 -50,000th part of the weight of the substance, occasion so great a difference in physical and chemical characters? The opinion of Mr. Tennant, that the difference depends on crystalliza- tion, seems to be correct. Transparent so- lid bodies are in general non-conductors of electricity ; and it is probable that the same corpuscular arrangements which give to mat- ter the power of transmitting and polarizing light, are likewise connected with its rela- tions to electricity. Thus water, the hy- drates of the alkalis, and a number of other bodies which are conductors of electricity when fluid, become non-conductors in their crystallized form. That charcoal is more inflammable than the diamond, may be explained from the looseness of its texture, and from the hydro- gen it contains. But the diamond appears to burn in oxygen with as much facility as plumbago, so that at least one distinction supposed to exist between the diamond and common carbonaceous substances is done away by these researches. The power pos- sessed by certain carbonaceous substances of absorbing gases, and separating colouring matters from fluids, is probably mechanical, and dependent on their porous organic structure ; for it belongs in the highest de- gree to vegetable and animal charcoal, and it does not exist in plumbago, coak, or an- thracite. The nature of the chemical difference be- tween the diamond and other carbonaceous substances, may be demonstrated by ignit.ng them in chlorine, when muriatic acid is pro- duced from the latter, but not the former. The visible acid vapour is owing to the mois- ture present in the chlorine uniting to the dry muriatic gas But charcoal, after be- ing intensely ignited in chlorine, is not al- tered in its conducting power or colour This circumstance is in favour of the opi- nion, that the minute quantity of hydrogen is not the cause of the great difference be- tween the physical properties of the diamond and charcoal.* It does not appear that any sum exceed- ing one hundred and fifty thousand pounds has been given for a diamond. *DICHROITE. See IOHTE.* DIGESTION. The slow action of a splvent upon any substance. DIG DIG * DTGHSTTO-V. The conversion of food into thyme in the stomach of animals by the solvent power of the gastric juice. Some interesting researches have been lately made on this subject by Dr. Wilson Philip and Dr. Front. JPltenomenrt) &?f nit, a!- tmminous principle. On being evaporate u to dryness, and burned, it yielded very copious traces of an alkaline muriate, with slight traces of an alkaline phosphate and sulphate; also of various earthy salts, as the sulpha te phesphate, and carbonate of lime. "The fi ret thing," says Dr. P. "which strikes the eye on inspecting the stomachs of rabbits which have lately eaten, is, that the new is never mixed with the old food. The former is always found in the centre sur- rounded on all sides by ihe old food, except that on the upper part between the new food and the smaller curvature of the stom- ach, there is sometimes little or no old food. If the old and the new food are of different kinds, and the animal be killed after taking the latter, unless a great length of time has elapsed after taking it, the line of separation is perfectly evident, so that the old may be removed without disturbing the new food. " it appears that in proportion as the food is digested, it is moved along the great cur- vature, when the change in it is rendered Biore perfect, to the pvloric portion. The layer of food lying next the surface of the Stomach, is first digested. In proportion as this undergoes the proper change, it is moved on by tiie niiiscuLr action of the stomach, and that next in turn succeeds to undergo the same change. Thus a continual motion is going on; that part of the food which lies next the surface of the stomach passing to- wards the pylorus, and the more central parts approaching the surface." Dr. Philip has remarked, that the great end of the stomach is the part most usually found acted upon by the digestive fluids after death. The following phenomena were observed by Dr. Prout: Comparative examination of the contents of the duodena of t?vo dogs, one of -which had been fed on vegetable food, the other on animal food rmhj. The chymous mass from vegeta- ble food (principally bread) was composed of a semi-fluid, opaque, yellowish-white part, containing another portion of a similar co- lour, but firmer consistence, mixed with it. Its specific gravity was 1.056. It showed no traces of a free acid, or alkali; but coagu- lated milk completely, when assisted by a gentle heat. That from animal food was more thick and viscid than that from vegetable food, and its colour was more inclined to red. Its sp. gr. was 1.022. It showed no truces of a free acid or alkali; nor did it coagulate milk even when assisted by the most favour- able circumstances. On being subjected to analysis, these two specimens were found to consist of Chyme from Chyme from vegetable food, ammul lood. Water, bb.6 bO.O Gastric principle, united with the alimentary matters, and apparent- ly constituting the chyme, mixed with excrementitious mat- ter, ... 6.0 15.8 Albuminous matter, part- ly consisting of fibrin, derived from the flesh on which the animal had been fed, Biliary principle, - 1.6 Vegetable gluten? - 5.0 Saline matters, Insoluble residuum, 0.7 0.2 100.0 1.3 1.7 0.7 0.5 100.0 Very similar phenomena were observed in other instances. But when the animal was opened at a longer period after feeding, Dr. Prout generally found much stronger evi- dences of albuminous matter, not only in the duodenum, but nearly throughout th whole of the small intestines. The quantity, hov.'i ver, was generally very minute in the iieuin; and where it enters "the coecum, no DIS DIS traces of this principle could be perceived See SANGUIFICATION.* DIGESTIVE SALT. Muriate of potash. DIGESTER. The digester is an instrument invented by Mr. Papin about the beginning of the last century. It is a strong vessel of copper or iron, with a cover adapted to screw on with pieces of felt or paper inter- posed. A valve with a small aperture is made in the cover, the stopper of which valve may be more or less loaded either by actual weights, or by pressure from an ap- paratus on the principle of the steelyard. The purpose of this vessel is to prevent the loss of heat by evaporation. The solvent power of water when heated in this vessel is greatly increased. * DIOPSIDE. A sub-species of oblique edg- ed augite. Its colour is greenish-white. It occurs massive, disseminated, and crystalliz- ed: 1. In low oblique four-sided prisms. 2. The same, truncated on the acute lateral edges, bevelled on the obtuse edges, and the edge of the bevelment truncated. 3. Eight-sided prisms. The broader lateral planes are deeply longitudinally streaked, the others are smooth. Lustre shining and pearly. Fracture uneven. Translucent. As hard as augite. Sp. gr. 3. 3 It melts with difficulty before the blow-pipe. It consists of 57.5. silica, 18.25 magnesia 16.5 lime, 6 iron and manganese. Lmtgier. It is found in the hill Ciarmetta in Piedmont; also in the black rock at Mussa, near the town of Ala, in veins along with epidote or pistacite, and hyacinth -red garnets. It is the Alalite and Mussite of Bonvoisin.* * DIOPTASK. Emerald copper-ore.* * DIPPEL'S animal oil, an oily matter ob- tained in the igneous decomposition of horns in a retort. Rectified, it becomes colourless, aromatic, and as light and volatile as ether. It changes sirup of violets to a green from its holding a little ammonia in solution.* * DIPYHE. Schmelszstein. This mineral is distinguished by two char- acters; it is fusible with intumescence by the blow-pipe, and it e mits on coals a taint phosphorescence. It is found in small prisms united in bundles, of a grayish or reddish- white. These crystals are splendent, hard enough to scratch glass; their longitudinal fracture is lamellar, and their cross fracture conchoidal. Its sp. gr. is 2.63. The primi- tive form appears to be the regular six-sided prism. It consists of 60 silica, 24 alumina, 10 lime, 2 water, and 4 loss. Vmtquelin. It occurs in a white or reddish steatite, mingled with sulphuret of iron, on the right bank of the torrent of Mauleon in the western Py- renees.* * DISTILLATION. The yaporization and subsequent condensation of a liquid, by means of an alembic, or still and refrigera- tory, or of a retort and a receiver. The old distinctions of distiUatio per latiis, per asctn- sum, and f>er decenaiim, are now discarded. Under LABORATOH?, a drawing and de- scription of a large still of an ingenious con- struction is given. The late celebrated Mr. Watt having ascertained, that liquids boiled in vaciio at much lower temperatures than under the pressure of the atmosphere, appli- ed this fuct to distillation; but he seems, ac- cording to Dr. Black's report of the experi- ment, to have found no economy of fuel in this elegant process ; for the latent heat of the vapour raised in vacito, appeared to be considerably greater than that raised in or- dinary circumstances. Mr. Henry Tritton has lately contrived a very simple apparatus for performing this operation in raciio ; and though no saving of fuel should be made, yet superior flavour may be secured to the dis- tilled spirits and essential oils, in conse- quence of the moderation of the heat. The still is of the common form; but instead of being placed immediately over a fire, it is immersed in a vessel containing hot water. The pipe from the capital bends down and terminates in a cylinder or barrel of metal plunged in a cistern of cold liquid. From the bottom of this barrel, a pipe proceeds to another of somewhat larger dimensions, which is surrounded with cold water, and furnished at its top with an exhausting syringe. The pipe from the bottom of the still, for emptying it, and that from the bottom of each barrel, are provided with stop-cocks. Hence, on exhausting the air, the liquid will distil rapidly, when the body of the alembic is surrounded with boiling water. When it is wished to withdraw a portion of the dis- tilled liquor, the stop-cock at the bottom of the first receiver is shut, so that on opening that at the sec >nd, in order to empty it, the vacuum is maintained in the still. It is evi- dent that the first receiver may be surround- ed with a portion of the liquid to be distil- led, as I have already explained in treating of alcohol. By this means the utmost econ- omy of fuel may be observed. . The term distillation, is often applied in this countr), to the whole process of con- verting malt or other saccharine matter, into spirits or alcohol. In making malt whiskey, one part of bruis- ed malt, with from four to nine parts of bar- ley meal, and a proportion of seeds of oats, corresponding to that of the raw grain, is in- fused in a mash-tun of cast iron, with from 12 to 13 wine gallons of water, at 150* Fahr. for every bushel of the mixed farina- ceous matter. The agitation then given by manual labour or machinery to break down and equally diffuse the lumps of meal, con- stitutes the process of mashing. This opera- tion continues two hours or upwards, accord- ing to the proportion of tmmaltei barley;. DIS DIS during which the temperature is kept up, by the effusion of seven or eight additional gal- lons of water, a few degrees under the boil- ing temperature. The infusion termed -wort having become progressively sweeter, is al- lowed to settle for two hours, and is run off from the top, to the amount of about one- third the bulk of water employed. About eight gallons more of water, a little under 200 F. are now admitted to the residuum, infused r nearly half an hour with agita- tion, and then left to subside for an fcour and a half, when it is drawn off. Some- times a third affusion of boiling water, equal to the first quantity, is made, and this infu- sion is generally reserved to be poured on new farina; or it is concentrated by boiling and added 10 the former liquors. In Scot- land, the distiller is stipposed by law, to ex- tract per cent 14 gallons of spirits, sp. gr. 0.91917, or 1 to 10 over proof; and must pay duty accordingly. Hence, his wort must have at least the strength of 55 pounds of saccharine matter, per barrel, previous to letting it down into the fermenting tun; and the law does not permit it to be stronger than 75 pounds. Every gallon of the above spirits contains 4.6 pounds of alcohol, sp.gr. 0.825, and requires for its production the complete decomposition of twice 4.6 pounds of sugar = 9.2 pounds. But since we can never count on decomposing above four- fifihs of the saccharine matter of wort, we must add one-fifth to 9.2 pounds, when we shall have 11^ pounds for the weight of saccharine matter, equivalent in practice to one gallon of the legal spirits. Hence, the distiller is compelled to raise the strength of lies wort up to nearly 70 pounds per barrel as indicated by his saccharometer. This concentration is to be regretted, as it mate- rially injures the flavour of the spirit. The thinner worts of the Dutch, give a decided superiority to their alcohols. At 62 pounds per barrel, we should have about 12 per cent of spirits of the legal standard. To prevent acetification, it is necessary to cool the worts down to the proper fer- menting temperature of 70, or 65, as ra- pidly as possible. Hence, they are pumped immediately from the mash-tun into exten- sive wooden troughs, two or three inches deep, exposed in open sheds to the cool air; or they are made to traverse the convolu- tions of a pipe, immersed in cold water. The wort being now run into the ferment- ing 1 tun, yeast is introduced and added in nearly equal successive portions, during three days; amounting in all to about one gallon, for every two bushels of farinaceous matter. The temperature rises in three or four days, to its maximum of 80; and at the end of 10 or 12 days the fermentation is completed; the tuns being closed up during the last half of the period. The distillers do not collect th yeast from their fermenting tuns, but allow it to fall down, on the supposition that it en- hances the quantity of alcohol. The specific gravity of the liquid has now probably sunk from 1.060, that of wort equivalent to about 56 pounds per barrel, to 1.005, or 1.000; and consists of alcohol mix- ed with undecomposed saccharine and fari- naceous matter. The larger the proportion of alcohol, the more sugar will be preserved unchanged; and hence the impolicy of the present laws on distillation. Some years ago, when the manufacturer paid a duty for the season, merely according to the measurement of his still, it was his in- terest to work it off with the utmost possible speed. Hence the form of still and furnace described under LABOUATOKY, was contrived by some ingenious Scotch distillers, by which means they could work off in less than four minutes, and recharge, an 80 gallon still; an operation which had a few years before last- ed several days, and which the vigilant fra- mers of the law, after recent investigation, deemed possible only in eight minutes. The waste of fuel was however great. The du- ties being now levied on the product of spi- rit, the above contest against time no longer exists. It has been supposed, but J think on insufficient grounds, that quick distilla- tion injures the flavour of spirits. This I believe to depend, almost entirely, on the mode of conducting the previous fermenta- tion. In distilling off the spirit from the ferment- ed wort or wash, a hydrometer is used to as- certain its progressive diminution of strength, and when it acquires a certain weakness, the process is stopped by opening the stop- cock of the pipe, which issues from the bot- tom of the still, and the spent wash is re- moved. There is generally introduced into the still, a bit of soap, whose oily principle spreading on the surface of the boiling li- quor, breaks the large bubbles, and of course checks the tendency to froth up. The spirits of the first distillation, called in Scotland low wines, are about 0.975 sp. gravity, and contain nearly 20 percent of alcohol of 0.825. Redistillation of the low wines, or doubling, gives at first the fiery spirit called first -shot, milky and crude, from the presence of a lit- tle oil. This portion is returned into the low wines, "What flows next is clear spirit, and is received in one vessel, till its density di- minish to a certain degree. The remain- ing spirituous liquor, culled faints, is mixed with low wines, and subjected to another dis- tillation. The manufacturer is hindered by law from sending out of his distillery, stronger spirits than 1 to 10 over hydrometer proof, equivalent to sp. gr. 0.90917; or weaker spi- rits than 1 in 6 under proof, whose sp. gr. isfl.9385. DIS DOL The following is said to be the Dutch mode of making Geneva: One cwt. of barley malt and two cwts. of rye meal are mashed with 460 gallons of water, heated to 162F. After the/orin^ have been infused for a sufficient time, cold water is added, till the wort becomes equiva- lent to 45 pounds of saccharine matter per barrel. Into a vessel of 500 gallons capa- city, the wort is now put at the temperature of 80, with half a gallon of yeast. The fermentation instantly begins, and is finished in 48 hours, during which the heat rises to 90. The wash, not reduced lower than 12 or 15 pounds per barrel, is put into the still along with the grains. Three distilla- tions are required; and at the last, a few juniper berries and hops are introduced to communicate flavour. The attenuation of 45 pounds in the wort, to only 15 in the wash shows that the fermentation is here very imperfect and uneconomical; as indeed we might infer from the small proportion of yeast, and the precipitancy of the process of fermentation. On the other hand, the very large proportion of porter yeast in a cor- rupting state, used by the Scotch distillers, cannot fail to injure the flavour of their spirits. Rum is obtained from the fermentation of the coarsest sugar and molasses in the West Indies, dissolved in water in the proportion of .nearly a pound to the gallon. The yeast is procured chiefly from the rum tvort. The preceding details give sufficient instruction for the conduct of this modification of the process. Sykes* hydrometer is now universally used in the^collection of the spirit revenue in Great Britain. It consists, first of a flat stem, 3.4 inches long, which is divided on both sides into 11 equal pails, each of which is subdivided into two, the scale being num- bered from to 11. This stem is soldered into a brass ball 1.6 inch in diameter, into the under part of which is fixed a small co- nical stem 1.13 inch long, at whose end is a pear-shaped loaded bulb, half an inch in diameter. The whole instrument, which is made of brass, is 6.7 inches long. The in- strument is accompanied with 8 circular weights, numbered 10, 20, 30,40, 50, 60,70, 80, and another weight of the form of a paral- lelopiped. Each of the circular weights is cut into its centre, so that it can be placed on the inferior conical stem, and slid down to the bulb; but in consequence of the enlargement of the cone, they cannot slip off at the bottom, but must be drawn up to the thin part for this purpose. The square weight of the form of a parallelepiped, has a square notch in one of its sides, by which it can be placed on the summit of the stem. In using this instru- ment, it is immersed in the spirit, and press- ed down by tire hand to O, till the whole di- vided part of the stem be wet. The force of the hand required to sink it, will be a guide in selecting the proper weight. Having taken one of the circular weights, which is- necessary for this purpose, it is slipped on the conical stem. The instrument is again immersed and pressed down as before to O, and is then allowed to rise and settle, at any point of the scale. The eye is then brought to the level of the surface of the spirit, and the part of the stem cut by the surface, as seenfrom below, is marked. The number thus indicated by the stem is added to the number of the weight employed, and with this sum at the side, and the temperature of the spirits at the top, the strength per cent is found in a table of 6 quarto pages. The strength is expressed in numbers denoting the excess or deficiency per cent of proof- spirit in any sample, and the number itself (having its decimal point removed two places to the left) becomes a factor, whereby the gauged content of a cask or vessel of such, spirit being- multiplied, and the product be- ing added to the gauged content, if over proof, or deducted from it if under proof, the result will be the actual quantity of proof spirit contained in such cask or ves- sel."* *DISTHENE. See CTASTITE.* * DISTINCT CONCHETJOXS. A term in MlXERALOGY.* DOCIMASTIC ART. This name is given to the art of assaying. See ASSAY, BLOW- PIPE, ANALYSIS, and the several metals. *DOLOMITE. Of this calcareo-magneaan carbonate, we have three sub-species 1. Dolomite, of which there are two kinds. 1st. Granular Dolomite. White granular. It occurs massive, and in fine granular distinct concretions, loosely aggregated. Lustre glimmering and pearly. Fracture in the large, imperfect slaty. Faint- ly translucent. As hard as fluor. Brittle Sp. gr. 2.83. It effervesces feebly with acids. Phosphorescent on heated iron, or by friction. Its constituents are 46.5 car- bonate of magnesia, 52.08 carbonate of lime, 0.25 oxide of manganese, and 0.5 oxide of iron. Klaproth. Beds of dolomite, con- taining tremolite, occur in the island of lona, in the mountain group of St. Gothard, in the Appenines, and in Carinthia. A beautiful white variety used by ancient sculptors, is found in the Isle of Tenedos. Jameson. The flexible variety was first noticed in the Bprghese palace at Rome; but the other varieties of dolomite, and also common gra- nular limestone, may be rendered flexible, by exposing them in thin and long slabs to a heat of 480 Fahr. for 6 hours. 2d, Brown Doloinite, or magnesian lime- stone of Tennant. Colour, yellowish-gray and yellowish- brown. Massive, and in minute granulai' DRA DYE concretions. Lustre internally glistening. Fracture splintery. Translucent on the edges. Harder than calcareous spar. Brittle. Sp. gr. of crystals, 2.8. It dissolves slowly, and with feeble effervescence; and when calcined, it is long in re-absorbing carbonic acid from the air. Its constituents are, lime 29.5, magnesia 20.3, carbonic acid 47.2. Alumina and iron 0.8. Tennant. In the north of England it occurs in beds of considerable thickness, and great extent, resting on the Newcastle coal formatbn. In the Isle of Man, it occurs in a limestone which rests on gray-wacke. It occurs in trap-rocks in Fifeshire. When laid on land after being calcined, it prevents vegetation, unless the quantity be smalll. To the proceeding variety we must refer zjleocible dolomite found near Tinmouth Cas- tle. It is >ello wish -gray, passing into cream- yellow. Massive. Dull. Fraciure earthy. Opaque. Yields readily to the knife, in thin plates, very flexible. Sp. gr. 2.54; but the stone is porous. It dissolves in acids as readily as common carbonate of lirne. Its constituents are said to be 62 carbona-.e of lirne, and 06 carbonate of magnesia. When made moderately dry, it loses its flexibility; but when either very moist or very dry, it is very flexible. 2d. Columnar Do'omite. Colour pale gray- ish-white. Massive, and in thin prismatic concretions. Cleavage imperfect. Fracture uneven. Lustre vitreous, inclining to pearly. Breaks into acicular fragments. Feebly translucent. Brittle. Sp. gr. 2.76. Its con- stituents are 51 carbonate of lime, 47 car- bonate of magnesia, 1 carbonated hydrate of iron. It occurs in serpentine in Kussia. 3d, Compact Dolomite, or Gurhoflte. Co- lour snow-white. Massive. Dull. Fracture rlat conchoidal. Slightly translucent on the edges. Semi-hard. Difficultly irangible. Sp. g-r 2.76. When pulverized, it dissolves with effervescence in hot nitric acid. It consists of 70.5 carbonate of lime, and 29.5 carbonate of magnesia. It occurs in veins in serpentine rocks, near GurhofT, in Lower Austria.* DHACO-MITIGATUS. Calomel. See MER- etjiir.* * DRAGON'S BLOOD. A brittle dark red coloured resin, imported from the East In- dies, the product afpterocarput draco, anddra- Gisna draco. It is insoluble in water, but soluble in a great measure in alcohol. The solution imparts a beautiful red stain to hot marble. It dissolves in oils. It contains a little benzoic acid.* *DaAwiNe SLATE. Black chalk. Co- lour grayish black. Massive. Lustre of the principal fracture, glimmering; of the cross fracture, dull. Fracture of the former slaty, of the latter, tine earthy. Opaque. it writes. Streak same colour, and glis- tening. Very soft. Sectile. Easily fran- gible. It adheres slightly to the tongue, Feels fine, but meagre. Sp. gr. 2.11. It is infusible. Its constituents are, silica 64.06, alumina 11, carbon 11, water 7.2, iron 2.75 It occurs in beds in primitive and transition clay-slate, also in secondary formations. It is found in the coal formation of Scotland, and in most countries. It is used in crayon- painting. The trace of bituminous shale is brownish and irregular; that of black chalk is regular and black. The best kind is found in Spain, Italy, and France.* DUCTILITY. That property or texture of bodies, which renders it practicable to draw them out in length, while their thickness is diminished without any actual fracture of their parts. This term is almost exclusively applied to metals. Most authors confound the words malle- ability, laminability, and ductility together, and use them in a" loose indiscriminate way; but they are very different. Malleability i* the property of a body which enlarges one or two of its three dimensions, by a blow or pressure very suddenly applied. Lamina- bility belongs to bodies extensible in dimen- sion by a gradually applied pressure. And ductility is properly to be attributed to such bodies as can be rendered longer and thin- ner by drawing them through a hole of less area than the transverse section of the body so drawn. DTEIXO. The art of dyeing consists in fixing upon cloths of various kinds any co- lour which may be required, in such a man- ner as that they shall not be easily altered by those agents, to which the cloth will most probably be exposed. As there can be no cause by which any colouring matter can adhere to any cloth, except an attraction subsisting between the two substances, it must follow, that there will be few tinging matters capable of in- delibly or strongly attaching themselves by simple application. Dyeing is therefore a chemical art. The most remarkable general fact in the art of Dyeing, consists in the different de- grees of facility, with which animal and vegetable substances attract and retain co- louring matter, or rather the degree of faci- lity with which the dyer finds he can tinge them with any intended colour. The chief materials of stuff to be dyed are wool, silk, cotton, and linen, of which the former two are more easily dyed than the latter. This has been usually attributed to their greater attraction to the tinging matter. Wool is naturally so much disposed to combine with colouring matter, that it re- quires but little preparation for the imme- diate process of dyeing; nothing more being required than to cleanse it, by scour- iujf, from a fatty substance, called the DYE DYE which is contained in the fleece. For this purpose an alkaline liquor is necessary; but as alkalis injure the texture of the wool, a very weak solution may be used. For if more alkali were present than is sufficient to convert the yolk into soap, it would at- tack the wool itself. Putrid urine is there- fore generally used, as being- cheap, and containing 1 a volatile alkali, which, uniting with the grease, renders it soluble in water. Silk, when taken from the cocoon, is co- vered with a kind of varnish, which, be- cause it does not easily yield either to wa- ter or alcohol, is usually said to be soluble in neither. It is therefore usual to boil the silk with an alkali, to disengage this mat- ter. Much care is necessary in this opera- tion, because the silk itself is easily cor- roded or discoloured. Fine soap is com- monly used, but even this is said to be de- trimental; and the white China silk, which is supposed to be prepared without soap, has a lustre superior to that of Europe. Silk loses about one-fourth of its weight by be- ing 1 deprived of its varnish. See BLEACH- ING. The intention of the previous prepara- tions seems to be of two kinds. The first to render the stuff or material to be dyed as clear as possible, in order that the aque- ous fluid to be afterward applied, may be imbibed, and its contents adhere to the mi- nute internal surfaces. The second is, that the stuff may be rendered whiter and more capable of reflecting the light, and conse- quently enabling the colouring matter to exhibit more brilliant tints. Some of the preparations, however, though considered merely as preparative, do real- ly constitute part of the dyeing processes themselves. In many instances a material is applied to the stuff, to which it adheres; and when another suitable material is ap- plied, the result is some colour desired. Thus we might dye a piece of cotton black, by immersing it in ink; but the colour would be neither good nor durable, because the particles of precipitated matter, formed of the oxide of iron and acid of galls, are al- ready concreted in masses too gross either to enter the cotton, or to adhere to it with any considerable degree of strength. But if the cotton be soaked in an infusion of galls, then dried, and afterward immersed in a solution of sulphate of iron (or other ferruginous salt), the acid of galls being every where diffused through the body of the cotton, will receive the particles of ox- ide of iron, at the very instant of their transmission from the fluid, or dissolved to the precipitated or solid state, by which means a perfect covering of the black inky matter will be applied in close contact with the surface of the most minute fibres of the cotton. This dve will therefore not Vol. T. only be more intense, but likewise more adherent, and durable. The French dyers, and after them the English, have given the name of mordant to those substances which are previously applied to piece goods, in order that they may afterward take a required tinge or dye. It is evident, that if the mordant be uni- versally applied over the whole of a piece of goods, and this be afterward immersed in the dye, it will receive a tinge over all its surface; but if it be applied only in parts, the dye will strike in those parts only. The former process constitutes the art of dyeing, properly so called; and the latter, the art of printing woollens, cot- tons, or linens, called calico-printing. In the art of printing piece goods, the mordant is usually mixed with gum or starch, and applied by means of blocks or wooden engravings in relief, or from cop- perplates, and the colours are brought out by immersion in vessels filled with suitable compositions. Dyers call the latter fluid the bath The art of printing affords many processes, in which the effect of mordants, both simple and compound, is exhibited. The following is taken from Berthollet. The mordant employed for linens, in- tended to receive different shades of red, is prepared by dissolving in eig'ht pounds of hot water, three pounds of alum, and one pound of acetate of lead, to which two ounces of potash, and afterward two ounces of powdered chalk, are added. In this mixture the sulphuric acid com- bines with the lead of the acetate and falls down, because insoluble, while the argilla- ceous earth of the alum unites with the acetic acid disengaged from the acetate of lead. The mordant therefore consists of of an argillaceous acetic salt, and the small quantities of alkali and chalk serve to neu- tralize any disengaged acid, which might be contained in the liquid. Several advantages are obtained by thus changing- the acid of the alum. First, the argillaceous earth is more easily disen- gaged from the acetic acid, in the subse- quent processes, than it would have been from the sulphuric. Secondly, this weak acid does less harm when it comes to be disengaged by depriving it of its earth. And thirdly, the acetate of alumina not being- crystullizable like the sulphate, does not separate or curdle by drying 1 on the face of the blocks for printing, when it is mixed with gum or starch. When the design has been impressed by transferring the mordant from the face of the wooden blocks to the cloth, it is then put into a bath of madder, with proper attention, that the whole shall be equally exposed to this fluid. Here the piece be- 46 DYE comes of a red colour, but deeper in those places where