THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID A COMPENDIUM OF. THE COURSE OF CHEMICAL INSTRUCTION IX THE MEDICAL DEPARTMENT OF THE UNIVERSITY OF PENNSYLVANIA. BY ROBERT HARE, M.D. PROFESSOR OF CHEMISTRY. IN TWO PARTS. PART I. COMPRISING THE CHEMISTRY OF HEAT AND LIGHT, AND THAT OF INORGANIC SUBSTANCES, USUALLY CALLED INORGANIC CHEMISTRY. ' FOURTH EDITION. WITH AMENDMENTS AND ADDITIONS. PHILADELPHIA: J. G. AUNER, No. 343 MARKET STREET. John C. Clark, Printer. 1840. I 40 PREFACE TO THE FIRST EDITION. WHERE a subject cannot be followed by a reader without study, it would seem unreasonable to expect that, without some assistance, it should be followed at a lecture. Under this impression, from the time that I became a lecturer, I applied myself so to improve and multiply the means and methods of experimental illustration, as to render manipulation easier, and the result more interesting and instructive. But notwithstanding all my efforts, there remained obstacles to be sur- mounted. However striking might be the experimental illustration of a property or principle, the rationale might be incomprehensible to a majority of my class, unless an opportunity for studying it were afforded them. Again, some of my contrivances, which greatly facilitated my experi- ments, were too complex to be understood without a minuteness of expla- nation, which, even if it were useful and agreeable to some of my hearers, might be useless and irksome to others ; and to such minutiae I have not deemed it expedient to exact attention. A chemical class, in a medical school, usually consists of individuals, who differ widely with respect to their taste for chemistry, and in opinion as to the extent to which it may be practicable or expedient for them to iearn it. There is also much disparity in the opportunities which they may have enjoyed, of acquiring some knowledge of this science, and of others which are subsidiary to its explanation. Hence a lecturer may expatiate too much for one portion of his auditors, and yet be too concise for another portion. While to the adept he may often appear trite, to the novice he may as often appear abstruse. Some pupils, actuated by a laudable curiosity, under circumstances per- mitting its indulgence, may desire an accurate knowledge of the apparatus by which my experimental illustrations are facilitated: other pupils may feel themselves justified, perhaps necessitated, not to occupy their time with the acquisition of any knowledge which is not indispensable to graduation. After some years' experience of the difficulties abovementioned, I came to the conclusion, that the time spent in the lecture room might be rendered much more profitable, if students could be previously apprized of the chain PREFACE. of ideas, or the apparatus and experiments, to be subjected to attention at each lecture ; especially as the memory might afterwards be refreshed by the same means. In consequence of this conviction, the minutes of my course of instruction were printed ; and subsequently a work, comprising engravings and descriptions of the larger portion of such of my apparatus and experiments, as could in this way be advantageously elucidated. En- couraged by the success of my plan, I am now preparing an edition which will be still more extensive. The work thus expanded, I have entitled " A Compendium of the Course of Chemical Instruction in the Medical School," &c. There will be much matter-in the Compendium, respecting which I shall not question candidates at the examination for degrees. With the essence of the larger part, I shall undoubtedly expect them to be acquainted ; but other portions have been introduced, that I may not be obliged to dwell upon them in my lectures, and that attention to them may be optional on the part of the students. To designate the portion of the work, respecting which candidates for degrees will not be questioned, I have had it printed in a smaller type, excepting where it was too much blended with subjects of primary importance to be separated. I wish it, however, to be under- stood, that I shall expect attention to the parts thus distinguished, so far as they may be necessary to a comprehension of the rest. Thus, although I do not deem it to be a part of my duty to question a pupil on pneumatics, I shall expect him to understand the influence of atmospheric pressure upon chemical reaction, and in pneumato-chemical operations. One great and almost self-evident advantage, resulting from my under- taking, I have yet to mention; I allude to the instruction which students may derive from the Compendium, either before or subsequently to their attendance on my lectures, and especially during the period which inter- venes between their first and second course. PREFACE TO THE FOURTH EDITION. THE suggestions, which were made in the Preface to the first edition of the Compendium, respecting the necessity of an appropriate text book, to aid and extend the instruction afforded by the course of chemical lectures, delivered in the Medical Department of the University of Pennsylvania, have acquired additional force since that Preface was written. During the twelve intervening years the boundaries of those portions of human knowledge over which Chemistry has established a rightful domain, have undergone an ex- tension commensurate with the time. It is, of course, proportionably more difficult to do justice to the whole of the wonderful region comprised within those boundaries in sixty lectures delivered within four months. Formerly, the attention of the student was alternately claimed by six professors; but latterly, the claims of a seventh professor have been added to those pre- viously established. Nevertheless, I am under the impression, that with the assistance which my text books are competent to afford, my course of lec- tures, brief as it is, may be more serviceable to a student who makes due use of those text books, than it could prove, were its duration doubled, with- out being associated with treatises made expressly for the purpose of ampli- fying the information partially afforded by my lectures, or of remedying their inevitable omissions. Having been prevented by indisposition from commencing this work as early as expedient, I am under the necessity of issuing that part which re- lates to Caloric, Light, and Inorganic Chemistry first. Dynamic Electri- city, comprising Galvanism or Voltaic Electricity, and Electro-magnetism, having been already issued, I shall in the next place republish my Treatise on Mechanical Electricity. Then to complete the new edition of my text books, only Organic Chemistry will remain to be reprinted. On this branch I hope to furnish a treatise before I reach that part of my course of lectures, in which it becomes the object of attention. I am in hopes that numbering the paragraphs, an excellent expedient re- sorted to by me for the first time in this edition, will be found advantageous to the reader, by rendering references from one part of the work to another less inconvenient, and consequently more frequent. CONTENTS. Page INTRODUCTION. Definition of Natural Philosophy, Chemistry, and Physiology - 1 Of Chemical reaction - 2 Of repulsive reaction, or repulsion - 2 I. CALORIC. Experimental proofs of a material cause of calorific repulsion 3 Expansion - 6 Expansion of solids - 6 Expansion of liquids - - 8 Expansion of aeriform fluids - - 10 Thermometers - 10 Modification of the effects of caloric by atmospheric pres- sure - 14 Capacities for heat, or specific heat - 44 Slow communication of heat, comprising the conducting process and circulation - - 47 Quick communication of heat, or radiation - 52 Means of producing heat, or rendering caloric sensible - 57 Means of producing cold, or rendering caloric latent - 68 States in which caloric exists in nature - - 74 II. Light - 75 Sources of light - 76 Heating, illuminating, and chemical properties of the rays 78 Polarization of light - 80 PONDERABLE MATTER. OF CERTAIN GENERAL PROPERTIES OF PONDERABLE MATTER AND THE MEANS OF ASCERTAINING OR INVESTIGATING THEM - 83 SECT. I. Chemical attraction - 83 Attraction of aggregation, or cohesion - - 83 Crystallization 84 Chemical affinity, or heterogeneous attraction - 89 II. Definite proportions - - - - 93 Tables of chemical equivalents - 94 Atomic theory - . 95 Chemical symbols - 96 Atomic weights and symbols of the simple substances - 97 III. Specific gravity - - - - 98 Definition and discovery of the aeriform fluids called gases '105 INORGANIC CHEMISTRY; OR CHEMISTRY OF INORGANIC SUBSTANCES. Individual ponderable elements - 110 BASACIGEN ELEMENTS - . no SECT. I. Oxygen . no II. Chlorine - - 117 Compounds of chlorine with oxygen - 123 Hypochlorous acid, or protoxide of chlorine - - 124 Ylll CONTENTS. Page Euchlorine, or impure chlorous acid 125 Chloric acid - 126 Oxychloric, or perchloric acid - 127 III. Bromine - - 128 Compounds of bromine with oxygen and chlorine - 129 Bromic acid - - - 1 29 Chloride of bromine - 130 IV. iodine - 130 Compounds of iodine with oxygen - 133 lodic, hyperiodic, and iodous acid - 133 Chlorides and bromides of iodine - - 133 V. Fluorine - - - - 134 VI. Sulphur - 134 Compounds of sulphur with oxygen - 137 Hyposulphurous acid - - 137 Sulphurous acid - - 137 Hyposulphuric acid - . - 138 Sulphuric acid - 139 Chlorides, bromide, and iodide of sulphur - 140 VII. Selenium - - 140 Compounds of selenium with oxygen - 141 VIII. Tellurium - 142 RADICALS - 143 NON-METALLIC RADICALS - 143 SECT. I. Hydrogen - 143 Compounds of hydrogen with oxygen - 150 Water - - 150 Deutoxide or bioxide of hydrogen - 156 Compound of hydrogen with chlorine - - 160 Chlorohydric or muriatic acid gas - 160 Old theory of the nature of chlorine and chlorohydric acid 165 Bromohydric acid - 165 lodohydric acid 165 Compounds of hydrogen with sulphur - - 166 Sulphydric acid, or sulphuretted hydrogen - 167 Polysulphide of hydrogen - 170 Compounds of hydrogen with selenium and tellurium - 171 Selenhydric acid, or selenuretted hydrogen - 171 Telluhydric acid, or telluretted hydrogen - 171 II. Nitrogen or azote - - 172 Atmospheric air - 174 Chemical compounds of nitrogen with oxygen - - 179 Protoxide of nitrogen, or nitrous oxide - 179 Nitric oxide, or nitrous air - 182 Hyponitrous acid - 183 Nitrous acid - - 184 Theory of volumes - - 187 Nitric acid - 190 Nitroso-nitric acid - - 192 Compounds of nitrogen with chlorine and iodine - - 195 Some points of chemical theory - - 195 Theories of combustion - 196 Influence of the habitudes of chemical agents with the Voltaic series, on classification and nomenclature 198 Methods of distinguishing degrees of oxidizement, de- rived from the school of Lavoisier - 199 Origin of the erroneous idea of an acidifying principle - 200 Acidity - 201 Alkalinity - 202 Compounds of nitrogen with hydrogen 204 CONTENTS. IX Ammonia, or the volatile alkali - 204 Ammonium - - 208 SECT. III. Phosphorus - - 211 Compounds of phosphorus with oxygen - - 214 Oxide of phosphorus - - 215 Hypophosphorous acid - 215 Phosphorous acid - 215 Phosphoric acid - 216 Chlorides of phosphorus - - 217 Bromides and iodides of phosphorus - 217 Sulphides and selenides of phosphorus - 217 Compounds of phosphorus with hydrogen - 218 Protophosphuretted hydrogen - - 218 Perphosphuretted hydrogen - - 218 IV. Carbon - 220 Compounds of carbon with oxygen - 224 Carbonic oxide - 224 Carbonic acid - - 225 Oxalic acid - 231 Mellitic acid - - 232 Croconic acid - - - 232 Compounds of carbon with oxygen and chlorine - - 232 Chloral - - 232 Chloroxycarbonic acid - - 233 Chlorides of carbon - 233 Bromide of carbon - 233 Iodides of carbon - - 233 Sulphocarbonic acid, or bisulphide of carbon - 234 Compounds of carbon with hydrogen - 234 Light carburetted hydrogen, or fire damp - 236 Safety lamp - - 236 Deutocarbohydrogen, or olefiant gas - - 237 Certain gaseous compounds formed by igniting gaseous elements of water with olefiant gas, &c. - 238 Other varieties of carbohydrogen - 240 Bicarburet of hydrogen - 240 Naphthaline - 240 Compounds of carbon with chlorine and hydrogen - 241 Compound of carbon with nitrogen - 241 Bicarburet of nitrogen, or cyanogen - - 241 Nomenclature of the compounds of cyanogen - 242 Cyanic, cyanuric, and fulminic acid - 243 Chlorides, bromides, and iodides of cyanogen - 245 Sulphocyanogen - 245 Sulphocyanhydric acid - - 245 Cyanhydric or prussic acid - - 246 V. Boron - 249 Compound of boron with oxygen - 250 Boric or boracic acid - ' - 250 Chloride of boron - 251 VI. Silicon - 251 Compound of silicon with oxygen - 253 Silica, or silicic acid - - 253 Glass - 254 Compounds of fluorine with hydrogen, boron, and silicon - 255 Fluohydric acid - 256 Fluoboric acid - - - 256 Fluosilicic acid - 257 Reaction of fluohydric acid with fluoboric and fluosilicic acid - 258 * X CONTENTS. Page SECT. VII. Zirconion 259 METALLIC RADICALS METALS OF THE EARTHS PROPER SECT. I. Aluminium - - 264 Alumina - - 265 Chloride of aluminium - - 268 II. Glucinium - - 268 Glucina - - 269 III. Yttrium - 269 Yttria - - 269 IV. Thorium - - 269 Thorina - - 270 METALS OF THE ALKALINE EARTHS - 270 SECT. I. Magnesium - - 270 Magnesia - - 270 II. Calcium, barium and strontium - 271 Evolution of calcium, barium and strontium - 272 III. Lime, or calcia, the oxide of calcium - 273 Baryta - - 275 Strontia - - 277 Peroxides or bioxides of barium and strontium - - 277 METALS OF THE ALKALIES, OR ALKALIFIABLE METALS - - 278 SECT. I. Potassium - - 278 II. Sodium - 279 Potash or potassa, and soda - - 280 Peroxides and suboxides of potassium and sodium - 283 III. Lithium - 284 Lithia - - 284 Reaction of chlorine, bromine, iodine, fluorine, and cyanogen, with the metals of the earths and alkalies - 284 Reaction of sulphur, selenium, and tellurium, with the metals of the earths and alkalies - 288 METALS PROPER - 289 SECT. I. Gold - 290 Compounds of gold with oxygen - - 291 Compounds of gold with the halogen class - 292 Compounds of gold with sulphur - - 292 II. Platinum - - 293 Compounds of platinum with oxygen - 294 Compounds of platinum with the halogen class - - 294 Compounds of platinum with sulphur - - 296 Power of platinum and other metals in a divided or spongy form to induce chemical reaction - - 296 III. Silver - 297 Compounds of silver with oxygen - 298 Compounds of silver with the halogen class - 299 Compounds of silver with sulphur - 299 IV. Mercury - - 300 Compounds of mercury with oxygen - - 302 Reaction of acids with mercury and its oxides - - 303 Chlorides of mercury - 304 Bromides, iodides, fluorides, and cyanides of mercury - 307 Compounds of mercury with sulphur - 308 Phosphurets of mercury - - 309 Combustion of mercury with chlorine - 309 V. Copper . 310 Compounds of copper with oxygen - 312 Compounds of the oxides of copper with acetic acid - 314 Compounds of copper with /the halogen class - 314 Compounds of copper with sulphur and selenium - 315 CONTENTS. XI Page VI. Lead - 315 Compounds of lead with oxygen - 316 Compounds of the protoxide of lead with acetic acid - 318 Carbonate of lead - 318 Compounds of lead with the halogen class - 319 Compounds of lead with sulphur and selenium - - 319 SECT. VII. Tin - - 320 Compounds of tin with oxygen - - 320 Compounds of tin with the halogen class - 321 Compounds of tin with sulphur and selenium. - 321 VIII. Bismuth - 322 Compounds of bismuth with oxygen - 323 Compounds of bismuth with the halogen class - - 323 Compounds of bismuth with sulphur and selenium - 324 IX. Iron - 324 Compounds of iron with carbon, boron, silicon, and phos- phorus - 325 Compounds of iron with oxygen - - 326 Reaction of iron with acids - 328 Compounds of iron with the halogen class - 329 Compounds of iron with sulphur and selenium - - 330 X. Zinc - 331 Compounds of zinc with oxygen - - 331 Compounds of zinc with the halogen class - 333 Compounds of zinc with sulphur and selenium - - 333 XI. Arsenic - 334 Compounds of arsenic with oxygen - 335 Compounds of arsenic with the halogen class - 338 Compounds of arsenic with sulphur and selenium - 338 Compounds of arsenic with phosphorus and hydrogen - 339 Means of detecting arsenic in cases where poisoning is sus- pected by it - 340 XII. Antimony - - 344 Sesquioxide of antimony - - 345 Compounds of antimony with oxygen of minor importance 346 Compounds of antimony with the halogen class - - 347 Compounds of antimony with sulphur and selenium - 347 XIII. Metals proper of minor importance - - - 350 Palladium - - - - 350 Rhodium - - 350 Iridium - - 351 Osmium - - 351 Nickel - - 351 Cadmium - - 352 Chromium - 352 Cobalt - - . 354 Columbium - 354 Manganese - - 354 Molybdenum - 354 Titanium - 355 Tungsten - 355 Uranium - - 355 Cerium - - 355 Vanadium - 355 SALTS - 356 SECT. I. Oxysalts - 359 Chlorates and hypochlorites - 359 Oxychlorates - 354 Nitrates - - 364 Nitrites and hyponitrites - - 365 Xll CONTENTS. Page Sulphates 365 Hyposulphates, sulphites, and hyposulphites 366 Seleniates - 366 Phosphates - 366 Phosphites - 366 Carbonates - 367 Borates - - 367 Silicates - - 367 Cyanates and fulminates - c 368 Double oxysalts - - - 368 SECT. II. Sulphosalts - 369 III. Selenisalts and tellurisalts - - 369 IV. Chlorosalts, bromosalts, iodosalts, and fluosalts - 370 V. Cyanosalts - - 370 DEFINITIONS OF CHEMISTRY. It is natural that a person whose attention may be directed to chemistry, should inquire of what does it treat, or how is it to be defined or distin- guished from other sciences 1 Agreeably to the definition given in the second page of the Compendium, chemistry treates of those phenomena and operations of nature which arise from reaction between particles of inorganic matter. I subjoin several other definitions from some of the most celebrated modern writers on chemistry. Thomson defines chemistry to be " the science which treats of those events or changes in natural bodies, which are not accompanied by sen- sible motions." Henry conceives that " it may be defined, the science which investigates the composition of material substances, and the permanent changes of constitution, which their mutual actions produce." According to Murray, " it is the science which investigates the combi- nations of matter, and the laws of those general forces, by which these combinations are established and subverted." Brande alleges "that it is the object of chemistry to investigate all changes in the constitution of matter, whether effected by heat, mixture, or other means." According to Z7re, " chemistry may be defined that science, the object of which is to discover and explain the changes of composition that occur among the integrant and constituent parts of different bodies." The definition given by Berzelius is as follows : " Chemistry is the science which makes known the composition of bodies, and the manner in which they comport with each other." COMPENDIUM OF CHEMICAL INSTRUCTION, &c. INTRODUCTION. 1. The phenomena and operations of the material world appear to be dependent on certain properties in the parti- cles or masses of matter which enable them to exercise a reciprocal influence. Without this reciprocal action, which I would prefer to call reaction,* every particle or mass would be as if no other existed, and could itself have no efficient existence. 2. The reciprocal action or reaction, thus inferred to exist, may be distinguished as taking place between masses, between a mass and particles, and between particles only. 3. Reaction between masses} is sublimely exemplified in the solar system, by that attraction between the sun and planets, by which they are made to revolve in their orbits. 4. Reaction between a mass and particles is exemplified by the reflection, refraction, and polarization of light. 5. Reaction between particles is exemplified by a fire, or the explosion of gunpowder. Definition of Natural Philosophy, Chemistry, and Physiology. 6. Natural Philosophy, in its most extensive sense, treats of physical reaction generally. In its more limited and * In Mechanics, action is said to produce reaction ; but in the case of an innate property, which mutually causes different portions of matter to be self attractive, or repellent, it is impossible to distinguish the agent from the reagent. From our first acquaintance with any bodies so situated, they may be said mutually to react, or to exercise reaction. t By the word mass, I mean a congeries of particles capable of producing some effect collectively, to which severally they would be incompetent. 1 2 INTRODUCTION. usual acceptation, it treats of those phenomena and ope- rations of nature, which arise from reaction between masses, or between a mass and particles. 7. Chemistry treats of the phenomena and operations of nature, which arise from the reaction between the particles of inorganic matter. 8. Physiology treats of the phenomena and operations, which arise from the reaction of the masses or atoms of organic or living bodies. OF CHEMICAL REACTION. 9. Reaction between particles, or chemical reaction, is distinguished into repulsive reaction or repulsion, and attractive reaction or attraction. OF REPULSIVE REACTION OR REPULSION. A Priori Proofs that there must be a Matter in which Re- pulsion exists as an Inherent Property. 10r Matter may be defined to be that which has proper- ties. We know nothing of matter directly. It is only with its properties that we have a direct acquaintance. It is from our perception of matter, through the powers or properties by which it affects our senses, that we believe in its existence. 11. The existence of repulsion and attraction is as evi- dent as that of the matter which, in obedience to their successive predominancy, may be seen either to cohere, in solids, with great tenacity, or to fly apart with explosive violence in the state of a vapour. The existence of re- pulsion and attraction being proved, it must be admitted that they are properties of matter ; since the existence of a property, independently of matter, is inconceivable. But being of a nature to counteract each other, the repellent and attractive powers cannot coexist in particles of the same kind, and consequently must belong to particles of different kinds. There must, therefore, be a matter en- dowed with repulsion, distinct from that which is endowed with attraction. 12. I conceive that the phenomena of chemistry demon- strate that there are at least the three following properties, which, from their obvious incompatibility, cannot belong to the same elementary particles. INTRODUCTION. .5 13. 1st. An innate property of reciprocal attraction. 14. 2d. An innate property of counteracting attraction directly, by imparting reciprocal repulsion. 15. 3d. An innate property of imparting an attraction, variable in its force, and limited and contingent in its du- ration. 16. I presume that there must be at least three different kinds of matter, to each of which, one of the properties thus specified innately appertains. 17. The permanent and unvarying attractive power is exemplified by gravitation, and, as modified by circum- stances, by tenacity, or cohesion. 18. It resides, undoubtedly, in every kind of matter en- dowed with weight, and consequently in all that is consi- dered as material by the mass of mankind. 19. It must likewise act between each of those impon- derable principles which I am about to mention, and all other matter, whether ponderable or imponderable. 20. The power of imparting reciprocal repulsion to ponderable matter is supposed by chemists generally to belong to certain imponderable material reciprocally repul- sive particles, constituting the cause of heat, called ca- loric. 21. The power of indirectly counteracting attraction, and substituting for it a contingent and variable attraction, appears to belong to electricity. Light also appears to exercise a modifying influence. 22. Thus we have reason to infer the existence of at least three imponderable substances electricity, caloric, and light each consisting of particles reciprocally repul- sive, yet attractive of other matter, and probably more or less attractive of each other. OF CALORIC. Experimental Proofs of the Existence of a material Cause of Calorific Repulsion. 23. It has been ascertained that ice melts and water freezes at the temperature of 32 of Fahrenheit's thermo- meter. If at this temperature, which is called the freezing point, ice in a divided state, as in that of snow for in- stance, be mingled with an equal weight of water at 172, 4 INTRODUCTION. the ice will be melted, and the resulting temperature will be 32 ; but if equal weights of water be mingled at those temperatures, the mixture will have the mean heat of 102. 24. It follows that a portion of heat becomes latent in the aqueous particles during the liquefaction of the ice, sufficient to raise an equal weight of water one hundred and forty degrees. In this case the ice is supposed to combine with material calorific particles, innately endowed with a power of reciprocal repulsion, and likewise with that of combining with ponderable matter. Hence w r ater is considered as a combination of ponderable particles, endowed with a reciprocally attractive power, and impon- derable particles endowed with a reciprocally repellent power ; so that, in obedience to the power last mentioned, the compound atoms, instead of cohering as in the solid state, move freely among each other, forming consequently a liquid. 25. In all cases of liquefaction or fusion which have been examined, analogous results have been observed; whence it is generally believed that whenever a solid is converted into a liquid, its particles unite with a portion of the material cause of heat, which becomes latent, as in the case of ice in melting. The evidence is equally strong in favour of the inference that in passing from the liquid to the aeriform state, ponderable matter combines with, and renders latent even a larger quantity of heat in proportion to its weight, than in cases of liquefaction. 26. When, by means of a thermometer, we observe the rise of temperature in water exposed to a regular heat, as when placed in a cup upon a stove, we find that nearly equal increments of heat are acquired in equal times, until the boiling point is attained. Subsequently, the cup being open so as to allow the steam to escape freely, no further rise of temperature will be found to ensue; but in lieu of it, steam will be evolved more or less copiously, in propor- tion to the activity of the fire. Since from the time the water boils it ceases to grow hotter, it may be fairly pre- sumed that the steam generated during the ebullition, al- though of a temperature no higher than 212, contains, in a latent state, the caloric which meanwhile enters the liquid. This presumption is fully justified by the fact, that if any given weight of steam be received in a quantity of CALORIC. O cool water ten times heavier, it will cause in it a rise of temperature of nearly one hundred degrees. 27. The heat which would raise ten parts of water to 100 degrees, would, if concentrated into one of those parts, raise it to 1000 degrees nearly, which is about equal to a red heat. It follows, therefore, that as much heat is ab- sorbed in producing steam, as would render the water of which it consists red-hot, if prevented from assuming the aeriform state. 28. These facts and deductions induce chemists general- ly to believe that the cause of calorific repulsions is mate- rial; that it consists of a fluid, of which the particles are self-repellent, while they attract other matter; that by the union of this fluid with other matter, a repulsive property is imparted, which counteracts cohesion, so as to cause, successively, expansion, fusion, afel^ the aeriform state ; and further, that it is by the afflux of the calorific matter that the sensation of heat is produced, while that of cold results from its efflux. 4* * Acceptation of the term Cal\-ic.\ . ^ 29. If we place a small heap of fulminating mercury upon the face of a hammer, and strike it duly with another hammer, an explosion will ensue so violent as to cause a visible indentation in the steel surface. This explosion, agreeably to the premises, can only be explained by sup- posing the evolution of a great quantity of the material cause of heat. Were an equal quantity of red-hot sand to be suddenly quenchecl with water, the effect would be com- paratively feeble. We may, therefore, infer that the ful- minating powder, though cold, contains more of the cause of heat than a like quantity of red-hot sand. Hence it would follow from using the word heat in the sense both of cause and effect, that there is more heat in a cold body than in a hot one, which in language is a contradiction. On this account it was considered proper by the chemists of the Lavoisierian school, to use a new word, caloric, to designate the material cause of calorific repulsion. Experimental Illustration. 30. A portion of fulminating mercury exploded between two hammers. IMPONDERABLE SUBSTANCES. ORDER PURSUED IN TREATING OF CALORIC. EXPANSION. MODIFICATION OF THE EFFECTS OF CALORIC BY ATMOS- PHERIC PRESSURE. CAPACITIES FOR HEAT, OR SPECIFIC HEAT. SLOW COMMUNICATION OF HEAT, COMPRISING THE CONDUCTING PRO- CESS AND CIRCULATION. QUICK COMMUNICATION OF HEAT, OR RA- DIATION. MEANS OF PRODUCING HEAT, OR RENDERING CALORIC SEN- SIBLE. MEANS OF PRODUCING COLD, OR RENDERING CALORIC LATENT. STATES IN WHICH CALORIC EXISTS IN NATURE. EXPANSION. OF THE EXPANSION OF SOLIDS, LIQUIDS, AND ELASTIC FLUIDS, AND ON THE OPPONENT AGENCY OF ATMOSPHERIC AND OTHER PRESSURE. Expansion of Solids. 31. A ring and plug, which when cold fit each other, cease to do so when either is heated; and a tire when red- hot is made to embrace a wheel otherwise too large for it. Pyrometer, in which the Extension, in length, of a Metallic Bar is ren- dered fensible by a Combination of Levers. 32. The influence of temperature on the length of a metallic wire may be rendered evident by means of the instrument, of which fig. 1, in the oppo- site engraving is a representation. 33. WW, represents a wire, beneath which is a spirit lamp consisting of a long, narrow, triangular vessel of sheet copper, open along the upper angle, so as to receive and support a strip of thick cotton cloth, or a suc- cession of wicks. By the action of the screw at S the wire is tightened, and by its influence on the levers, the index I is raised. The spirit lamp is then lighted and the wire enveloped with flame. It is of course heated and expanded, and, allowing more liberty to the levers, the index upheld by them falls. 34. By the action of the screw the wire may be again tightened, and, the application of the lamp being continued, will again, by a further expan- sion, cause the depression of the index ; so that the experiment may be repeated several times in succession. 35. Since this figure was drawn, I have substituted for the alcohol lamp the more manageable flame of hydrogen gas, emitted from a row of aper- tures in a pipe supplied by an apparatus for the generation of that gas. See fig. 2. 36. If, while the index is depressed by the expansion, ice or cold water be applied to the wire, a contraction immediately follows so as to raise the index to its original position. 37. Metals are the most expansible solids, but some are more expansible than others. 38. The following table, abstracted by Turner from that furnished by Lavoisier, will show the increase of bulk obtained by glass and various me- tals in rising in temperature from 32 to 212. Instrument far demonstrating the Power of Caloric in expanding a Metallic Rod. (Page 6.) CALORIC. Atau. cf Subnets. Glass tube without lead, mean of three specimens - - 1-1115 of its length. English flint glass, - 1-1248 Copper, 1-581 Brass, mean of two specimens, -532 Soft iron, forged, 819 Iron wire, --- -812 Untempered steel, 927 Tempered steel, 807 Lead, ' - .351 Tin of India, 516 Tin of Falmouth, 462 Silver, 524 Gold, mean of three specimens, -602 Platinum, determined by Borda, 1-1167 39. Pyrometers have been made of platinum, in one of which, invented by Daniell, changes in the length of a cylinder of this metal, arising from temperature, are made sensible by the motion of a lever associated with it, and which acts as an index. In the other, a bulb is formed of platinum, and the degree of heat is inferred from the quantity of air expelled. 40. The use of this air pyrometer is burdened by the necessity of mea- surement and calculation to ascertain the result. This might be very much facilitated by the use of a sliding rod and air-gauge. The retraction of the rod might be made to compensate the expulsion of air, while divisions well made on it would indicate the quantity. Experimental Illustration of the different Expansibility of Metals. 41. That the expansibility of one metal may exceed that of another, may be rendered apparent by soldering to- gether, face to face, two thin strips, one iron the other brass. On exposure to heat, the compound strip, thus constituted, assumes the shape of an arch. The brass, which is the more expansible metal, forms the outer and of course larger curve. Supposed Exception to the Law that Solids expand by Heat in the case of Clay, which contracts in the Fire. 42. The phenomena do not justify us in considering the contraction of clay from heat as an exception to the ge- neral law. In the first instance clay shrinks by losing water, of which the last portions are difficult to expel. In the next place a chemical union takes place between the principal ingredients, silica and alumina, which is rendered more complete in proportion to the duration and intensity of the fire. It may be presumed that the vitreous com- 8 IMPONDERABLE SUBSTANCES. pound, which would result from a complete fusion and combination of the constituents, would be as expansible as other vitreous substances. Experimental Illustration. 43. The contraction produced by heat in cylinders of clay shown by means of the ingenious but inaccurate pyro- meter of Wedgwood. Expansion of Liquids or non-elastic Fluids. 44. The word fluid applies to every mass that will flow, distribute itself equally in obedience to its own weight or self-repulsion. 45. Ponderable fluids are either elastic or non-elastic. Latterly the term liquid has been employed to designate those fluids which are, like water, alcohol, and oil, devoid of elasticity, a property which, in due time, I shall define and illustrate. Liquids are expanded when their Temperature is raised, and some Liquids are more expansible than others. N N IlilllllillllillllllliilHIii CALORIC. 46. Let two glass vessels be provided with bulbs and necks of the same shape and dimensions as represented in the preceding figure. Let one of them, that on the left for instance, be supplied with as much alcohol as will occupy it to the level designated by the letters O O. Let the ves- sel on the right be occupied with water to the same level, the height of the liquid in each being made to correspond with a little fillet of white paper secured about the neck. Under each vessel, place equal quantities of charcoal, burn- ing with a similar degree of intensity ; or preferably, sur- round the bulbs simultaneously with hot water in an oblong vessel of suitable dimensions. The liquids in each vessel will be expanded so as to rise into the necks; but the alco- hol will rise to a greater height than the water. 47. The dilatation of the following liquids, by a change of temperature from 32 to 212, is as follows alcohol 1-9, nitric acid 1-9, fixed oils 1-12, sulphuric ether 1-14, oil of turpentine 1-14, sulphuric or muriatic acid 1-17, brine 1-20, water 1-23 nearly, mercury about 1-55. 48. The rate of expansion for liquids increases with the temperature; as if their particles, by becoming more re- mote, lost some of their ability to counteract the repulsive influence of caloric. 49. The number associated with each of the substances in the following list, shows its melting point as estimated by Fahrenheit's scale. One degree of Daniell's pyrometer, (39) by which the temperatures above 600 were measured, is calculated to be equal to seven of Fahrenheit. 50. Cast iron 3479, gold 2590, silver 2233, brass 1869, antimony 810, zinc 648, lead 606, bismuth 497, tin 442, sulphur 218, beeswax 142, spermaceti 112, phos- phorus 108, tallow 92, olive oil 36, milk 30, blood 2.5, sea water 272, oil of turpentine 14, mercury 39, nitric acid 45^, sulphuric ether 46. Exception to the Law that Liquids expand by Heat. 51. The bulk of water diminishes with the temperature, until it reaches 39 nearly. Below this point, it expands as it grows colder, and in freezing increases in bulk one- ninth. This wonderful exception to the law that liquids expand by heat, appears to be a special provision of the Deity for the preservation of aquatic animals; for were 10 IMPONDERABLE SUBSTANCES. water to increase in density as it approaches the point of congelation, the upper stratum would continue to sink as refrigerated in bodies of water below 39, as well as in others. Hence a whole river, lake, or sea might, in high latitudes, be rendered too cold for animal life; and finally be so far converted into ice, as not to thaw during the ensuing summer. Subsequent winters co-operating, the whole might be consolidated so as never to thaw. But in consequence of the peculiarity in question, the cold- est stratum, in a body of water below 39, remains at top, until, if the cold be adequate, congelation ensues. The buoyant sheet of ice, which results in this case, forms effec- tively a species of winter clothing to the water beneath it; and, by augmenting with the frost, opposes an increas- ing obstacle to the escape of caloric from the water which it covers. Expansion of Aeriform Fluids. 52. Aeriform fluids are much more expansible than liquids. In order, however, to appreciate the changes of bulk which they may be observed to sustain, it is neces- sary to understand the influence which the pressure of the atmosphere has upon their density, independently of tempe- rature. The simple influence of heat, in expanding them, may be illustrated by holding a hot iron over the thermo- meter of Sanctorio, represented in the following figure. Thermometers. 53. The invention of the thermometer is ascribed to Sanctorio. The principle of that form of the instrument which he contrived may be understood from the following article. CALORIC. 11 Expansion of Air illustrated by the Air Thermometer of Sanctorio on a large Scale. 54. The bulb of a matrass is support- ed by a ring and an upright wire with its neck downwards, so as to have its orifice beneath the surface of the water in a small glass jar. A heated iron being held over the ma- trass, the contained air is so much in- creasgd in bulk, that, the vessel being inadequate to hold it, a partial escape from the orifice through the water ensues. On the removal of the hot iron, the residual air regains its pre- vious temperature, and the portion expelled by the expansion is replaced by the water. 55. If in this case the quantity of air expelled be so regulated, that when the remaining portion returns to its previous temperature, the liquid rises about half way up the stem, or neck, the apparatus will constitute an air thermometer. For whenever the tem- perature of the external air changes, the air in the bulb of the matrass must, by acquiring the same temperature, sustain a corresponding increase or diminution of bulk, and consequently, in a proportionate degree, influ- ence the height of the liquid in the neck. As elastic fluids are dilated equably, in proportion to the temperature, and are also much more expan- sible than liquids, this thermometer would be very accurate, as well as pre-eminent in sensibility, were it not influenced by atmospheric pressure as well as temperature. On this account, however, it was never of much utility. Subsequently, liquids were resorted to, and the instrument assumed the form now generally employed, the principle of which is explained. (45.) 56. In the following pages I shall give engravings and descriptions of the form of the thermometer used in the laboratory, of the self- registering thermometer, of the differential thermometer, and of an apparatus which illustrates the difference between it and Sanctorio's thermometer. 57. Agreeably to the example of my predecessor and preceptor Dr. Woodhouse, I have been accustomed to exhibit to my class the blowing and filling of a thermometer. Of this process an account is subjoined. 58. The tubes used in constructing thermometers are made at almost all the glass houses, having usually a capillary perforation. They are made by rapidly drawing out a hollow glass globe while red-hot, by which means it is changed into a long cylindrical string of glass, in the axis of which a perforation exists, in consequence of the cavity of the globe. When a thermometer tube is softened by exposure to a flame, excited by a blow-pipe, a bulb may be blown upon it. While the bulb is still warm, the other end of the tube is immersed in mercury, or in spirit, according to the purposes for which the instrument is intended. As the bulb cools, the air within it contracts, and thus allows the liquid to enter, in obedience to the pressure of the atmosphere. The bulb thus becomes partially supplied with the liquid, which is next boiled in order to expel all the air from the cavity of the bulb and perforation. 12 IMPONDERABLE SUBSTANCES. The orifice being again depressed into the liquid, when the whole becomes cold the liquid will fill the cavity of the bulb. This result will be hereafter fully explained and illustrated. The open end of the tube being now heated, is drawn out into a filament with a capillary perforation. The bulb being raised to a temperature above the intended range of the thermometer, so as to expel all the superabundant liquid, the point is fused so as to seal the orifice hermetically, or in other words so as to be perfectly air-tight. In the next place, the bulb is to be exposed to freezing water, and the point to which the liquid reaches in the capillary perforation marked. In like manner the boiling point is determined, by subjecting the bulb to boiling water. The distance between the freezing and boiling points, thus ascertained, may be di- vided according to the desired graduation. 59. The scale of Reaumur requires 80 divisions, that of Celsius 100, Fahrenheit's 180. The graduation of Celsius is the most rational ; that of Fahrenheit the least so, although universally used in Great Britain and the United States. The degrees of these scales are to each other obviously, as 80, 100, and 180; or as 4, 5, and 9. Hence it is easy to convert the one into the other by the rule of three. 60. It should, however, be observed that the scales of Celsius and Reaumur com- mence at the freezing of water, all above that being plus, all below it minus ; while the scale of Fahrenheit commences at thirty-two degrees below freezing. Hence in order to associate correctly any temperature noted by his thermometer with theirs, we must ascertain the number of degrees which the mercury is above or below freezing, and convert this number into one equivalent to it by their gradua- tion ; and conversely, after changing any number of degrees of theirs into his, we must consider the result as indicating the number of degrees above or below 32 on his scale. 61. The process above described for the construction of a thermometer, is equally applicable whether the bulb be filled with alcohol or mercury. Each of these liquids has peculiar advantages. Mercury expands most equably. Equal divisions on the scale of the mercurial thermometer will more nearly indicate equal incre- ments or decrements of temperature. Mercury also affords a more extensive range ; as it does not boil below 656, nor freeze above 39, of Fahrenheit's thermometric scale. 62. Alcohol, being more expansible than mercury, is more competent to detect slight changes. It boils at 176 of Fahrenheit, and for its congelation is alleged to require 90 of the same scale. As this temperature is below any ever observed in nature, and can only be attained by an extremely difficult process, latterly disco- vered by Bussier, it can hardly ever happen that an alcoholic thermometer will not be found competent to measure any degree of cold which chemists have a motive for determining. Besides those above mentioned, a thermometric scale has been used in Russia, which bears the name of its author, Delisle. In this, zero is at the boiling point of water, and five of his graduations are equal to six of Fahrenheit's. Laboratory Thermometer. 63. The thermometers used in laboratories, are usually con- structed so as to have a portion of the wood or metal, which defends them from injury and receives the graduation, to move upon a hinge, as represented in the adjoining figure. 64. This enables the operator to plunge the bulb into fluids, without introducing the wood or metal, which would often be detrimental either to the process or to the instru- ment, if not to both. 65. The scale is kept straight by a little bolt on the back of it, when the thermometer is not in use. Self-registering Thermometer. O rrm . i i i i i i i i i i 1 1 i i J I I I 1 L CALORIC. 13 66. This figure represents a self-registering thermometer. It comprises necessarily a mercurial and a spirit thermometer, which differ from those ordinarily used, in hav- ing their stems horizontal and their bores round ; also large enough to admit a cylin- der of enamel in the bore of the spirit thermometer, and a cylinder of steel in the bore of the mercurial thermometer. Both the cylinder of enamel and that of steel must be as nearly of the same diameter with the perforations in which they are respec- tively situated, as is consistent with their moving freely in obedience to gravity, or any gentle impulse. 67. In order to prepare the instrument for use, it must be held in such a situation, as that the enamel may subside as near to the end of the alcoholic column as possible, yet still remaining within this liquid. The steel must be in contact with the mer- cury, but not at all immersed in it. 68. On this account the bulbs of the thermometers are placed at opposite ends of the plate upon which they are secured ; so that when this plate is made to stand up on one end, in such manner as to have the bulb of the mercurial thermometer lower- most, that of the spirit thermometer will be uppermost. Under these circumstances, impelled by gravity, the steel cylinder will subside upon the surface of the mercurial column, while the cylinder of enamel will sink within the little column of spirit, which retains it, till it reaches the surface of that column. The instrument being, after this object is attained, suspended in a horizontal position, as represented in the figure, if in consequence of its expansion by heat, the mercury advance into the tube, the steel moves before it; but should the mercury "re tire during the absence of the observer, the steel does not retire with it. Hence, the maximum of temperature, in the interim, is discovered by noting the graduation opposite the end of the cylin- der nearest the mercury. The minimum of temperature is registered by the enamel, which retreats with the alcohol when it contracts, but, when it expands, does not advance with it. The enamel must retire with the alcohol, since it lies at its mar- gin, and cannot remain unmoved in the absence of any force competent to extricate it from a liquid, towards which it exercises some attraction. But when an opposite movement lakes place, which does not render its extrication from the liquid neces- sary to its being stationary, the enamel does not accompany the alcohol. Hence the minimum of temperature, which may have intervened during the absence of the ob- server, is discovered by ascertaining the degree opposite the end of the enamel near- est to the end of the column of alcohol. Leslie's Differential Thermometer. o o 69 This instrument consists of a glass tube nearly in the form of the letter U, with a bulb at each termination. In the bore of the tube there is some liquid, as, for instance, coloured sulphuric acid, alcohol, or ether. When such an instrument is exposed to any general alteration of temperature in the surrounding medium, as in the case of a change of weather, the air in both bulbs being equal- ly affected, there is no movement produced in the fluid; but the opposite is true, when the slightest change of temperature exclusively affects one of the bulbs. Any small bodies situated at different places in the same apartment warmed by a fire, will show a diversity of temperature, when severally applied to the different bulbs. 14 IMPONDERABLE SUBSTANCES. 15 Difference between an Air Thermometer and a Differential Thermometer, illustrated upon a large Scale. 70. The adjoining figure represents an instrument, which acts as an air thermometer, when the stopple S is removed from the tubulure in the coni- cal recipient, R; because in that case, whenever the density of the atmos- phere varies either from changes in temperature, or barometric pressure, hereafter to be explained, the extent of the alteration will be indicated by an increase or diminution of the space occupied by the air in the bulb, B, and of course by a corresponding movement of the liquid in the stem, T. But when the stopple is in its place, the air cannot, within either cavity of the instrument, be affected by changes in atmospheric pressure : nor can changes of temperature which operate equally on botii cavities, produce any movement in the liquid which sepa- rates them. Hence, under these cir- cumstances, the instrument is compe- tent to act only as a differential ther- mometer. MODIFICATION OF THE EFFECTS OF CALORIC BY ATMOS- PHERIC PRESSURE. Digression to demonstrate the Nature and Extent of Atmospheric Pressure. Experimental Proof that Air has Weight. 71. The air being allowed to replenish an exhausted globe, while suspended from a scale beam and accurately counterpoised, causes it to preponderate. 72. By a temporary communication with an air pump, by means of a screw with which it is furnished, a glass globe is exhausted of air. It is then suspended to one arm of a scale beam, and accurately counterpoised. Being thus pre- pared, if by opening the cock the air be al- lowed to re-enter the globe, it will preponde- rate; and if a quantity of water, adequate to restore the equilibrium, be introduced into a small vessel, duly equipoised by a counter- weight applied to the other arm of the beam, the inequality in bulk of equal weights of air and water will be satisfactorily exhibited. CALORIC. 15 Definition of Elasticity. 73. The power which bodies have to resume their shape, position, or bulk on the cessation of constraint, is called elasticity. The degree in which any body possesses this power is not to be estimated by the force, but by the perfection of its recoil. A coach spring is far more powerful, but is not more elastic, than a watch spring. 74. Elasticity is erroneously spoken of as a varying property in the air, which, in common with aeriform fluids in general, appears to be always perfectly elastic. , 75. As a property distinguishing aeriform fluids from liquids, elasticity conveys the idea of a power in a given weight of a fluid to expand or to contract with the space in which it may be confined, producing at the same time a pressure on the internal surface of the cavity, or any object within it, inversely as the space. The Existence and Extent of the Pressure of the Atmosphere experimentally demon- strated. PRELIMINARY PROPOSITION. 76. For the pressure of any fluid on any area assumed within it, the pressure of a co- lumn of any other fluid may be substituted, making it as much higher as lighter, as much lower as heavier; or in other words, the heights are inversely as the gravities. Experimental Illustration in the case of Mercury and Water. 77. If into a tall glass jar, such as is represented in the adjoining figure, a glass cylinder, C, (like a large glass tube open at both ends) were introduced on filling the jar with water, this liquid would of course rise in the cylin- der to the same height as in the jar; but, if, as in the figure, be- fore introducing the water, the bottom of the jar be covered with a stratum of mercury, two inches deep, so as to be sufficiently above the open end of the cylinder, it must be evident that the water will be prevented from entering the cylinder by the interposition of a heavier liquid. But as the pressure of the water on the mer- cury outside of the cylinder is unbalanced by any pressure from water within the cylinder, the mercury within will rise, until, by its weight, the external pres- sure of the water is compensated. When this is effected, it will be seen, on comparing, by means of the scale, S, the height of the two liquids, that for every inch of elevation acquired by the mer- cury, the water has risen more than a foot; since the weight of mercury is to that of water, as 13.6 to 1. 16 IMPONDERABLE SUBSTANCES. 78. It may be demonstrated that the pressure of the column of mercury is exactly equivalent to that of a column of water having the same base, and an altitude equal to that of the water in the jar, by filling the cylinder with water. It will then be seen, that, when the water inside of the cylinder is on a level with the water on the outside, the mercury within the cylinder is also on a level with the mercury without. 79. It is, therefore, obvious, that the elevation of the column of mercury, within the tube, is produced by the weight or pressure of the water without, and measures the extent of that pressure on the lower orifice of the tube. The Illustration extended to the case of Liquids lighter than Mercury. 80. Let there be four jars, each about four inches in diameter, and more than thirty inches in height, severally occupied by mercury to the depth of about two inches. In the axis of each jar, let a tube be placed, of about one inch and a half in diame- ter, and about one-fourth taller than the jar, with both ends open, and the lower orifice under the surface of the mercury. On pouring water into the jars, the mer- cury rises in the tubes, as the water rises in the jars; but the mercury rises as much less than the water as it is heavier. 81. The mercurial columns in this case, as in the preceding experiment, owe their existence to the pressure of the surrounding water, and by their height measure the extent of that pressure on the areas of their bases respectively. They may be considered as substituted severally for the aqueous columns, which would have en- tered the tubes had not the mercury been interposed. Accordingly, water being poured into one of the tubes, the mercury in that tube subsides to a level with the mercury without, when the water poured into the tube reaches the level of the water without. 82. The three remaining columns of mercury may be considered as substituted, in water, for columns of water, and being as much lower as heavier are found ade- quate to preserve the equilibrium. 83. It remains to be proved that other fluids, heavier or lighter than water, may in like manner be substituted for the columns of mercury, and of course for the water of which the mercury is the representative. CALORIC. 17 84. Into the three tubes, in which, by the addition of water to the jars, columns of mercury are sustained, pour severally, ether, alcohol, (differently coloured, so that they may be distinguished) and a solution of sulphate of copper, until the mercurial columns, within the tubes, are reduced to a level with the mercury without. It will be found that the column formed by the cupreous solution is much lower than the surface of the water on the outside of the tube ; that the opposite is true of the column of alcohol ; and that the ether, still more than the alcohol, exceeds the sur- rounding water in elevation. 85. While it is thus proved that columns of mercury, ether, alcohol, and of a saline liquid may, in water, be substituted for columns of this liquid; it is also appa- rent that they must be as much higher as lighter, as much lower as heavier; or in other words, their heights must be inversely as their gravities. Torricellian Experiment. 86. Pursuant to the law which has been above illustrated, that the pressure of one fluid may be substituted for that of another, provided any difference of weight be compensated by a corresponding difference in height; if, in lieu of water, the mer- cury were pressed by air on the outside of the tubes, unbalanced by air within, co- lumns of the metal would be elevated, which would be in proportion to the height and weight of the air thus acting upon it. 87. In order to show that the air exercises a pressure on the mercury outside of the tubes, analogous to that exercised by water in the experiments just described, it is only requisite that this external pressure be unbalanced by the pressure of air within the tube. This desideratum is obtained by filling, with mercury, a tube about three feet in length, open at one end and closed at the other, and covering the open end with the hand, until it be inverted and merged in a vessel containing some of the same metal, without allowing any air to enter. A mercurial column of about 30 inches in height will remain in the tube, supported by the pressure of the sur- rounding air, and an index of its weight. This is a case obviously analogous to that of the mercurial columns, supported by the pressure of water in the experi- mental illustration above given. 88. The tube may be supposed to occupy either of the three posi- tions, represented in the drawing. The mercury, in each position, preserves the same degree of ele- vation, its surface being always in the same horizontal plane, or level, whether upright or inclined. Or we may suppose three tubes, filled with mercury, and inverted in a vessel, nearly full, of the same metal, to be placed in the positions represented in the draw- ing. The upper surfaces of the columns of mercury in each tube, will be found always coincident with the same horizontal plane, however different may be the an- gle which they make with the horizon. And the horizontal plane, in which their surfaces are thus found, will be between 28 and 31 inches above the surface of the mercury in the vessel. The line, L, with which the mercury in each of the tubes is on a level, represents a cord rendered horizontal, by mak- ing it parallel with the surface of the mercury in the reservoir. 18 IMPONDERABLE SUBSTANCES. Additional Illustration of Atmospheric Pressure. 89. I trust that the preceding illustrations are well adapted to convey a clear concep- tion of atmospheric pressure ; but as it some- times happens, fortuitously, that when truth cannot get access to the mind under one form, it may reach it in another, even when less eligible, I subjoin the following illustra- tion, which, though less amusing, and asso- ciating with it fewer instructive phenomena, is more brief, and perhaps equally conclu- sive. 90. If a tube, recurved into a crook at one end so as to form a syphon, with legs of very unequal length, and both ends open, have the crook lowered into water, as in the adjoining figure, the fluid will of course, rise within the tube to the same height as without. But i'f, before the crook is sunk in the fluid, it be occupied by mercury, the water will enter the tube, only so far as the pressure which it exerts upon the mercury in the short leg of the syphon, is competent to raise the mercury in the long leg. 91. This pressure, or the effort of the water to enter the tube, is obviously measured by the height to which it forces the mercury, in the long leg of the syphon, above the mercurial surface in the short leg. The height will of course be greater or less, in proportion to the depth to which the lower surface of the mercury may be sunk. It will also be greater or less, according as the fluid in which it is immersed is heavier or lighter. Hence, as water is about 820 times heavier than air, a depth of 820 inches in air would displace the mercury as much as one inch in water. 92. Let us imagine a tube recurved at one end, similarly to the one represented in the foregoing figure, the crook likewise occupied by mercury, to have the upper orifice as completely above the atmpsphere, as the orifice of the tube is above the water in the jar. The mercury, in the short leg of the syphon, thus situated, would be evidently exposed to a pressure, caused by the air analogous to that sustained from water, in the case of the tube, as already illustrated; and this pressure of the air would, as in the case of the water, be measured by the rise of the mercury in the long leg of the syphon. 93. Yet to realize this experiment with a syphon reaching above the atmosphere, it is obviously impossible ; but, as the only motive for giving such a height to the syphon is to render the mercury in the long leg inacessible to atmospheric pressure, if this object can be otherwise attained, the phenomenon may be exhibited in the case of the atmosphere without any material deviation. 94. In fact, to protect the mercury in the long leg from atmospheric pressure, we have only to seal the orifice of that leg, and, through the orifice of the other, to fill the syphon with mercury, before we place it in a vertical position. We shall then find that the pressure of the air on the mercury, in the open leg of the syphon, will support a column of this metal in the other leg of nearly thirty inches, though occa- sionally varying from 28 to 31 inches. Inferences respecting the Weight of the Atmosphere from the preceding Experiments. 95. Supposing the base of the column of mercury, sustained by the atmosphere, as demonstrated in the preceding articles, were equivalent to a square inch, the total weight of the column would be about fifteen pounds. This of course represents the weight of that particular column of air only, whose place it has usurped; and as, for every other superficial inch on the earth's surface, a like column of air exists, the earth must sustain a pressure from the "atmosphere, equal to as many columns of mercury, 30 inches high, as could stand upon it; or equal to a stratum of mercury of the height just mentioned, extending all over the surface of the globe. CALORIC. 19 96. It has been shown that the heights of heterogeneous fluids, reciprocally resist- ing each other, are inversely as their gravities ; or, in other words, that they are as much higher as lighter, as much lower as heavier. The height of the column of air which, by its pressure, elevates the mercury, must, therefore, be as much greater than the height of the column of mercury, as the weight of the mercury is greater than the weight of the air, supposing the air to be of uniform density. Mercury is 11152 times heavier than air, and of course the height of the atmosphere would be (if uniform in density) 11152 X 30 inches = 27880 feet; supposing 30 inches to be the height of the mercurial column supported. 97. Hence the atmosphere, if of the same density throughout as on the surface of the earth, would not extend much above the elevation ascribed to the highest moun- tains. 98. But as the pressure of the atmosphere causes its density, it may be demon, strated that, the heights increasing in arithmetical progression, the densities will decrease in geometrical progression. Thus at an elevation of three miles, the air being, by observation, half as dense as upon the earth's surface: At 6 miles it will be i At 21 miles it will be T | T 9 .... I 24 .... ^ 12 .... T V 27 -. - fa 15 .... 7 V 30 ... ! 18 .... ,I T or rarer than we can render it by the finest air pump. These results have been verified, to a considerable extent, by actual observation. 99. It is reasonable to suppose that there is a degree of rarefaction, at which the weight of the ponderable particles of the air will be in equilibrio with the repulsive power of the caloric united with them. Beyond the distance from the earth's sur- face at which there should be such an equilibrium, the air could not exist. Hence it is inferred that the extent of our atmosphere is limited. Of the Water Pump. 100. The admission of the atmosphere is necessary to the suction of the water from a receiver. Air may be removed from close vessels by the same process. Water rises by the pressure of the atmosphere j air presses out by its own elasticity. Mechanism and Action of the Suction Pump rendered evident by means of a Model with a Glass Chamber. Difference between pumping an Elastic Fluid and a Liquid, illus- trated by an appropriate Contrivance. 101. A little suction pump is constructed, with a chamber C C, of glass, which permits the action of its piston, P, and valves to be seen. Below the pump is a hollow glass globe filled with water. This globe communicates with the pump by a tube, visibly descending from the lower part of the pump, through an aperture in the globe, till it nearly reaches the bottom. This tube is luted air-tight into the aper- ture by which it enters the globe. Its orifice, next the chamber, is covered by a valve opening upwards. In the axis of the piston there is a perforation, also covered by a valve opening upwards. 102. If the piston, P, be moved alternately up and down as usual in pumping, as often as it rises its valve will shut close ; so that if nothing passes by the sides of the piston, nor enters into the chamber of the pump from below, a vacuum must be formed behind the piston. Under these circumstances, it might be expected that the water would rise from the globe through the lower valve, and prevent the forma- tion of a vacuum. But being devoid of elasticity, and, therefore, incapable of self, extension beyond the space which it occupies, the water does not rise into the chain, ber of the pump, so long as by means of the cock, C, of the recurved pipe, PP, com. munication with the external air is prevented. But if this cock be opened during the alternate movement of the piston, a portion of the water will mount from the globe into the chamber at each stroke of the piston. The opening of the cock per- mits the atmosphere to press upon the fluid in the globe, and to force it up the tube leading to the pump chamber, as often as the chamber is relieved from atmospheric pressure by the rise of the piston. As soon as the piston descends, the valve over the orifice of the tube shuts, and prevents the water from returning into the globe. It is of course forced through the perforation in the piston, so as to get above it. 20 IMPONDERABLE SUBSTANCES. When the piston rises, the valve over its perforation being shut, it lifts the portion of water above this valve until it runs out at the nozzle of the pump; while the chamber, below the piston, receives another supply from the globe. But if after all the water has been pumped from the globe, the pumping be continued with the cock closed , a portion of air will be removed from the globe at each stroke, until the resi- due be so much rarefied, as, by its elasticity, no longer to exert against the valve, closing the tube, sufficient pressure to lift it, and thus to expand into the vacuity formed behind the piston, as often as it rises. 103. The rarefaction thus effected in the air remaining in the globe, is rendered strikingly evident, by causing the orifice of the curved tube to be under the surface of some water in an adjoining vase, while the cock is opened. The water rushes from the vase into the exhausted globe with great violence ; and the extent of the rarefaction is demonstrated by the smallness of the space within the globe which the residual air occupies, after it is restored to its previous density by the entrance of the water. (Pago 21.) CALORIC. 21 Description of a Chemical Implement. 104. The operation of sucking up a liquid through a quill, arises from the partial removal of atmospheric pressure from within the quill by the muscular power of the mouth. There is a great analogy between the mode in which suction is ef- fected by the mouth, and that in which a liquid is made to rise into the bulb of an implement which I am about to describe, and which is very useful for withdrawing small portions of liquids from situations from which otherwise they cannot be removed without inconvenience. 105. This instrument is constructed by duly attaching a bag of caoutchouc to the neck of a glass bulb with a long tapering perforated stem. 106. In order to withdraw from any vessel into which the stem will enter, a portion of any contained liquid, it is only necessary to compress the bag so as to exclude more or less of the air from within it ; then to place the orifice of the stem be- low the surface of the liquid, and allow the bag to resume its shape. Of course, the space within it becoming larger, the air must be rarefied, and inadequate to resist the pressure of the atmosphere, until enough of the liquid shall have entered to restore the equilibrium of density between the air within the bag and the atmosphere. The air within the bag cannot, however, fully resume its previous density ; since the column of the liquid counteracts, as far as it goes, the atmospheric pressure. Indeed, this counteracting influence is so great in the case of mercury, that the instrument cannot be used with this liquid. It is however the only substance, fluid at ordinary temperatures, which is too heavy to be drawn up into the bulb of the instrument in question, when fur- nished with a stout bag. Of the Mr Pump. Difference between the Mr Pump and the Water Pump. 107. The action of the air pump is perfectly analogous to that of the water pump; as there is no difference between pumping water and pumping air, excepting that which arises from the nature of the fluids; the one being elastic, the other, in common with liquids in general, almost destitute of elasticity. 108. In the air pump, as in the water pump, therefore, there is a chamber, and an upper and lower valve, which operate in the same manner as the valves of the water pump already described. Description of a large Mr Pump with Glass Chambers. 109. The opposite engraving represents a very fine instrument of large size, ob- tained from Mr. Pixii, of Paris. 110. From the figure, it must be evident that this pump has two glass chambers. They are unusually large, being nearly three inches in diameter inside. The lower valvB, V, is placed at the end of a rod, which passes through the packing of the piston. Hence, during the descent of the piston, the friction of the packing against the rod, causes it to act upon the valve with a degree of pressure adequate to prevent anv escape of air, through the hole which it closes, at the bottom of the chamber. The air included between the piston and the bottom of the chamber, is, therefore, by the descent of the piston, propelled through a channel in the axis of the piston, covered by a valve opening upwards. When the motion of the piston is re- versed, the air cannot, on account of the last mentioned valve, return again into the cavity which the piston leaves behind it. But in the interim, the same friction of the packing, about the rod, which had caused it to press downwards, has now, in consequence of the reversal of the stroke, an opposite effect, and the valve V is lifted as far as a collar on the upper part of the rod will permit. The rise, thus permitted, is just sufficient to allow the air to enter the chamber through an aperture which the valve had closed, and which communicates by means of a perforation with a hole in the centre of the air pump plate, and of course with the cavity of the receiver, RR, placed over the plate. The reaction of the air in the perforation and pump chamber 22 IMPONDERABLE SUBSTANCES. being diminished, the air of the receiver moves into the chamber until the equili- brium of density is restored between the two cavities. The chamber will now be as full of air as at first; but the air with which it is replenished is not so dense as before, as the whole quantity in the receiver and the chamber scarcely exceeds that which had existed, before the stroke, in the receiver alone. By the next downward stroke, the air which has thus entered the chamber is propelled through the valve hole in the piston. Another upward stroke expels this air from the upper portion of the chamber; and the valve attached to the rod being again uplifted, the portion of the chamber, left below the piston, is supplied with another complement of air from the receiver : and thus a like bulk of air is withdrawn at every stroke of the pump. I say a like bulk of air, since the quantity necessarily varies with the density of the air in the vessel subjected to exhaustion. This density is always directly as the quantity of air remaining ; of course it finally becomes insignificant. Thus when the quantity, in the receiver, is reduced to one-hundredth of what it was at first, the weight of air removed, at each stroke, will be one-hundredth of the quantity taken at each stroke when the process began. 111. I have explained the action of one chamber only, as that of the other is ex- actly similar, excepting that while the piston of one descends, that of the other rises. 112. The gauge represented in the engraving, is one which I have contrived upon a well known principle. It consists of a globular vessel to hold mercury, supported upon a cock. The mercury is prevented from entering the perforation in the cock, by a tube of iron, surmounted by a smaller one of varnished copper, which passes up into a Torricellian glass tube till it reaches near the top. The glass tube opens at its lower extremity, under the surface of the mercury in the globe. The exhaustion of this tube, and that of any vessel placed over the air pump plate, proceed simulta- neously, and consequently the mercury is forced up from the globe into the glass tube to an altitude commensurate with the rarefaction. 113. By inspecting a scale, SS, behind the glass tube, the height of the mercury is ascertained. In order to make an accurate observation, the commencement of the scale must be duly adjusted to the surface of the mercury in the globe. On this account it is supported by sliding bands on an upright square bar, between the glass cylinders. 114. The receiver, RR, represented on the air pump plate, is one which I usually employ in exhibiting the artificial aurora borealis. The sliding wire, terminated by a ball, enables the operator to vary the distance through which the electrical corus- cations are induced. Experimental Illustrations of the Elastic Reaction of the Mr. Air occupying a small Portion of a Cavity, rarefied so as to fill the whole Space. 115. Air is dependent on its own weight for its density, and enlarges in bulk in proportion as the space allotted to it is enlarged. 116. The mode in which the air occupying but a small part of a vessel may be rarefied so as to fill the whole cavity, is shown by the experiment represented in the annexed engraving. A bladder is so suspended within a vessel included in a receiver, as that the cavity of the bladder communicates through its own neck and that of the vessel, with the cavity of the receiver; while no such communication exists between the receiver and the space between the bladder and the inside of the vessel. 117. Things being thus situated, and the receiver ex- hausted, the bladder contracts in consequence of the removal of air from ' within it, proportionably with the exhaustion of the receiver ; for, as the air between the outside of the bladder, and the inside of the vessel, is no longer resisted, within the bladder, by air of the same density, it expands into the space which the bladder had occupied, so as to reduce it into a very narrow compass. 118. This cannot excite surprise, when it is recollected that the air, confined between the outside of the blad- der and the inside of the vessel, had previously to the exhaustion been condensed by supporting the whole atmospheric pressure, and must of course enlarge itself from its elasticity, as that pressure is diminished. CALORIC. 23 Distcntion of a Caoutchouc Bag by the Rarefaction of confined Mr. 119. The power of any included portion of air to ex- tend itself in consequence of a removal of pressure, is illustrated in another way, by subjecting to a highly rarefied medium a gum elastic bag, its orifice being previously closed, so as to be air-tight. The bag will swell up in a most striking manner, in proportion to the diminution of power in the air without the bag to counteract the reaction of the air within it. 120. The experiment is reversed by subjecting a bag, while inflated, to the influence of a condenser, by which it may be reduced in size more than it had been expanded; the air within the receiver being rendered denser than without. 121. In the adjoining cut, the gum elastic bag is re- presented as when inflated. The glass represented below the bag, is one which happened to be used as a support when the drawing was made. Expulsion of a Liquid by the Rarefaction of Mr. 122. A flask, half full of water, is inverted in another vessel, having some water at the bottom, and both are placed, under a bell glass, on the plate of an air pump. As the bell is exhausted by the action of the pump, the air included in the flask enlarges its bulk, finally occu- pying the whole cavity, and partially escaping from the orifice through the water in the lower vessel. When the atmosphere is allowed to re-enter the bell, the water rises into the flask, so as to occupy as much more space than at first, as the air occupies less, in consequence of a portion having escaped as abovementioned. Experimental Proofs of the Weight of the Atmosphere. Atmospheric Pressure on the Hand. 123. If, as represented in this figure, the air be ex- hausted from a vessel covered by the hand, its re- moval will be found almost impracticable : for, sup- posing the opening which the hand closes to be equal to five square inches, at 15 Ib. per square inch, the pressure on it will evidently be seventy-five pounds. Bladder ruptured by the Weight of the Atmosphere. 124. Let there be a glass vessel open at both ends, as represented in this figure. Over the upper opening let a bladder be stretched and tied, so as to produce an air-tight juncture. For every square inch of its super- ficies, the bladder thus covering the opening in the vessel sustains a pressure of about 15 pounds. Yet this is productive of no perceptible effect; because the atmosphere presses upwards against the lower surface of the bladder, as much as downwards upon the upper surface. But if the vessel be placed upon the plate of an air pump, so that, by exhaustion, the atmosphe- 24 IMPONDERABLE SUBSTANCES. tic pressure downwards be no longer counteracted by its pressure upwards, the blad- der will be excessively strained, and usually torn into pieces. 125. When the bladder is too strong to be broken by the unassisted weight of the air, a slight score with the point of a penknife will cause it to be ruptured not only where the score is made, but in various other parts, so that it will, at times, be torn entirely from the rim of the vessel. R The Hemispheres of Otho Gueriche, the celebrated Inventor of the Air Pump. 126. Two brass hemispheres are so ground to fit each other at their rims as to form an air- tight sphere when united. One of the hemispheres is furnished with a cock, on which is a screw for attaching the whole to the air pump. Being by these means exhausted, the cock closed, and the ring, R, screwed on to the cock, great force must be exerted, before the hemispheres can be separated. Bottle broken by Exhaustion of the Mr from within. 127. Proof that a square glass bottle may be broken by atmospheric pressure on the outside, as soon as it ceases to be counteracted by the resistance of the air within. 128. The mouth of a square bottle being placed over the hole in an air pump plate, so as to be suffi- ciently tight for exhaustion, a few strokes of the air pump, by withdrawing the air from the interior, causes the bottle to be crushed. 129. A stout globular glass vessel, with an aper- ture at top, is placed over the bottle, to secure the spectators from the fragments. Bottle broken by Exhaustion of the Mr from without. 130. The elastic reaction of the air, confined within a square bottle, will burst it, as soon as relieved from the counteracting weight of the atmosphere. 131. If a thin square bottle, so sealed that while unbroken the contained air cannot escape, be placed within the receiver of an air pump, the exhaustion of the receiver will, by removing the pressure which counteracts the elastic reaction of the con- fined air, cause the bottle to be fractured. The Height of the Column of Mercury which balances the Atmosphere, shown by Exhaustion. 132. R, fig. 1, is a hollow glass cylinder, about 33 inches in height, and 2 inches in diameter, into the upper end of which a brass gallows screw, G, is cemented; so that by means of the flexible pipe communicating with the air pump plate, A, the cylinder may be exhausted. The mouth of the cylinder being immersed in mercury in the vase, the metal, as the exhaustion proceeds, rises in the cylinder, until it CALORIC. Zb reaches more or less nearly to the height at which it slando in a Torricellian tube, accordingly as the pump may be more or less perfect. FIG. 2. FIG. 1. Barometric Column of Mercury lowered by Exhaustion. 133. It has been shown that in a tube void of air, a mercurial column may be sup- ported at the height nearly of thirty inches; and this has been alleged to result from the pressure of the atmosphere on the surface of the mercury on the outside of the tube. 134. In order to verify this allegation, let a tube, fig. 2, supporting within it a column of mercury, be placed under a competent receiver upon the air pump plate. 135. It will be found that, as the air is withdrawn from the receiver, the mercury in the tube will subside, and, if the exhaustion be carried far enough, will sink to a level with the mercury on the outside. 136. If, while this experiment is performing, a communication exist between the air pump and the cylinder, R, employed in the preceding experiment, the mercury will rise in the cylinder, while it falls in the tube ; thus proving that the force which is required to remove the air from the outside of the tube and lower the mercury within it, is adequate to raise in the cylinder a mercurial column equal in height to that which is reduced. IMPONDERABLE SUBSTANCES. Of the Barometer Gauge. 137. While I am upon the' subject of atmospheric pressure, it appears to me expedient to give a de- scription of an instrument which, in several of my illustrations, is employed to ascertain the quantity of air within a receiver. 138. It consists of a barometer tube, 33 inches in height, supported in a vertical position by a pedes- tal, and a strip of wood, G- G. Attached to the latter is a brass scale, by which 30 inches is divided into 500 equal parts. The gauge tube is surmounted by a ferrule and gallows screw, by the aid of which a flexible leaden pipe, P, communicates with the bore of the tube. By means of the valve cock and gallows screw at V, this pipe may be made to com- municate also with the cavity to be measured, the valve cock enabling us to suspend the communica- tion when desirable. The lower orifice of the glass tube, T, is covered by mercury in a broad shallow ' receptacle, D. Supposing the cavity, under these circumstances, to be exhausted, and the communi- cation with the bore of the glass tube open, the ex- tent of the exhaustion, or, in other words, the quantity of air withdrawn, will 'be exactly in pro- portion to the rise of the mercury as indicated by the scale; and consequently, reversing the operation, the fall of the mercury, as indicated by the scale, will show the quantity of air which may be intro- duced. If we count the degrees upwards from the surface of the mercury in the receptacle, D, their number will show the quantity of air withdrawn. If we count the degrees downwards from the level of the top of the mercurial column in the barometer, the number will indicate the exact quantity of gas in the cavity examined. In short, the quantity taken out, or introduced, is always measured by the num- ber of degrees which the mercury rises or falls in consequence. It is preferable to have two scales, one beginning above, the other below. 139. This gauge may be employed to indicate the quantity of air in any cavity. It only requires accuracy in the divisions of the scale, and in the adjustment of zero to the proper level. As the height of the mercurial column in the barometer varies with those changes of atmospheric pressure which it is employed to indicate, there- fore, in counting downwards, care must be taken to place the commencement of the scale on a level with the upper end of a column of mercury in a good barometer, at the time. To facilitate this adjustment, I have occasionally placed a Torricellian tube by the side of the gauge tube. The top of the column of the mercury in the Torricellian tube is then the proper point for the upper zero. As the strip of wood to which the scale is attached slides upon the iron rod, R, the scale may be fixed at a proper height by a set screw.* 140. As a perfect vacuum cannot be produced by means of an air pump, in order to wash out of a receiver all traces of atmospheric air, it is necessary that portions of the gas to be substituted should be repeatedly introduced, and as often removed by exhaustion.! 141. The rise of the mercury in the tube, by diminishing the quantity in the re- ceptacle, D, will cause the surface of it to be lower; but the breadth of this vessel is so great, and the descent of the mercurial surface in it so inconsiderable, that no error worthy of attention is thus produced. 142. It is proper to mention that the cavity of the tube ought to be so small in proportion to that of the receiver, as to create no error worthy of attention. * Both the gauge tube and the rod, R, should be longer than they are represented in the figure. t One gas may be employed to wash another out of a cavity, in a mode analogous to that in which water may wash out alcohol, or alcohol water. CALORIC. 27 Apparatus for illustrating the Difference between the Lifting and Forcing Pumps. 143. The process by which the water is drawn into the chamber is the same in the case of the forcing as in that of the lifting pump. In the lifting pump, L, the water which has entered the chamber during the ascent of the piston, passes through the piston during its descent, and is lifted by it when the motion is reversed. In the forcing pump, F, the piston, being imperforate, forces, in descending, the water into the adjoining air vessel, A, whence its regress is prevented by a valve, V, The stroke being repeated, the water accumulates in the air vessel, compressing the con- tained air, until it reacts upon the water with sufficient force to cause an emission of this liquid through the jet pipe, J J, commensurate with the supply. Of Condensation. 144. It has been shown that, in consequence of the elasticity of the air, the quan- tity of this fluid, in any close vessel, may be diminished until the residual portion has, by the action of the air pump, become too rare to escape in opposition to the very slight resistance made by the valves. It remains to show that, in consequence of the same property, by an operation the converse of that of the air pump, the air in any adequate vessel may be made many times more dense than it would other- wise be. Of the Condenser. 145. The instrument employed for the purpose of condensing air is called a con- denser. 146. The air pump was illustrated by its analogy with the suction pump. There is the same analogy between the condenser and the forcing pump. In the air pump, the valve between the chamber and receiver opens towards the chamber; in the case of the condenser a corresponding valve opens towards the receiver. 147. Besides the valve thus placed between the chamber and receiver, there is in each pump another valve. In the air pump, the air passes this second valve only IMPONDERABLE SUBSTANCES. when the piston moves so as to lessen the vacancy between it and the bottom of the chamber ; in the condenser, the air passes only when the piston moves so as to en- large the vacancy. In other respects these machines are so much alike, that the one might be used for the other. In my experimental illustrations, I shall have occasion to employ instruments which serve either to exhaust or to condense, according to the aperture selected for making a communication with the receiver. FIG. 1. '. 148. Fig. 1, in the adjoining engraving, represents a condenser. It consists of a brass cylinder, A A, ground internally, so as to be perfectly cylindrical. Into this a piston, B, is fitted by means of oiled leathers packed between screws, repre- sented in the figure, and turned in the lathe, so as to enter the chamber in obedi- ence to considerable force. At the lower end of the rod, a perforation, C C, may be seen, which commences at the lower ex- tremity, rises vertically until it gets above the packing, and then passes out at right angles to its previous direction through the rod of the piston. Just above where it commences, a cavity, D, may be observed, which is left for the upper valve. This valve is formed of a strip of oiled leather tied over a brass knob represented within the cavity. 149. The upper and lower valves are ex- actly alike; hence, a good idea of either may be obtained from fig. 2, which affords a separate view of the lower valve. 150. The action of the condenser is as follows. When the piston is drawn up, all the air within the chamber gets below the packing through the perforation, C C, and the upper valve, which opens downwards with ease so as to afford a passage. When the piston descends, the air included in the chamber cannot get by the leather packing. The upper valve at the same time shuts so as to prevent it from getting through the perforation, C C. It has therefore to proceed through the lower perforation, E. The piston being drawn up again, the valve at E shuts and prevents a return of the air expelled, while the air of the chamber again gets below the piston as in the first instance. Thus, at every stroke, the contents of the chamber are discharged through the lower valve, while its retrocession from any receiver into which it may pass is prevented by the valve, E. 151. As the quantity of air in the vessel increases, the force requisite to drive the piston home becomes greater ; and it has to descend farther, ere the air within the chamber exceeds in density that in the receiver, so far as to open the lower valve. Influence of Pressure on the Bulk of Mr, and of its Density on its Resistance. 152. Mr lessens in bulk as the pressure which it sustains augments ; and the resist- ance arising from its elasticity is augmented, as. the quantity confined in the same space is increased, or the confining space diminished. 153. For the illustration of this proposition, I have devised the apparatus repre- sented in the opposite engraving. 154. If mercury bo poured into the air-tight vessel, A, through the tube, T T, which passes perpendicularly into this vessel until it touches the bottom ; as the air in the vessel cannot escape, it is gradually reduced in bulk, but at the same time re- acts upon the surface of the metallic liquid with a force which becomes greater, in proportion as its bulk is lessened. Hence an increasing mercurial column will be upheld, which by its height indicates the resistance. When the air in the vessel has been reduced to half its previous bulk, the height of the mercury in the tube will be about '.50 inches, or equal to that of the mercury in the barometer at the time of Apparatus for illustrating the Influence, of Pressure on the Bulk of Air. T (Page 28.) CALORIC. 4\) performing the experiment. Thus it is shown, that when air is condensed into half the space which it occupies under the pressure of the atmosphere, its reactive power is doubled, being adequate to support a column of mercury equal to the pressure of the Atmosphere, in addition to that pressure. It follows that the quantity of air oc- cupying any space is as the pressure, and is always to that of an equal bulk of the atmosphere, as the height of the column of mercury which the said air can support in a Torricellian tube, is to the height of the mercury in the barometer: and like- wise, that the resistance of air increases with the diminution of the including space ; or, vice versa, that the space which a given weight of air is capable of occupying, lessens as the pressure increases. 155. It remains to be shown that the resistance of air to compression increases as the quantity in any space increases. 156. If, by means of the condenser, C, (the valve cock, v c, and the cock, c, being open,) air be injected into the vessels, A and B at the same time, it will be found that the liquid in the vase, V, will mount into the flask, F, and that when the pres- sure is adequate to cause the air in this to be reduced to half its previous volume, the mercury in the tube, TT, will have the same height as in the previous experi- ment ; because the density of the air, and of course its quantity and reactive power, are doubled in one case no less than in the other. 157. The communication between the condenser and the receiver, A, is suspended during the first mentioned experiment, by closing the valve ccck, v c. This cock is opened during the action of the condenser in the second experiment; and like- wise another cock at c, which serves to intercept the communication between the condenser and the receiver, B. Mechanical Action of the Lungs in Respiration illustrated. 158. The elevation of the sternum rarefies the air within the cavity of the thorax. Consequently, the atmospheric pressure not being adequately resisted, the external air rushes through the trachea into the lungs, dilating all the cells. The depression of the sternum and consequent diminution of the cavity cause the air which had thus entered, or an equivalent portion, to flow out. For the illustration of the pro- cess here described, I have contrived the apparatus represented below. 159. A tall receiver, R, with an orifice, O, is placed in a globe containing water, R 30 IMPONDERABLE SUBSTANCES. so that about two-thirds of the receiver are occupied by this liquid, the remainder with air, whilst a bladder is so suspended from the orifice as not to touch the water. 160. The atmosphere has access to the cavity of the bladder through its neck, and through the orifice O of the receiver, but not to the space A, between the outside of the bladder and the inside of the receiver. 161. It may be assumed as an obvious consequence of the preceding experiments, (154, 156) that the pressure, exerted by any given quantity of air, is inversely as the confining space ; or in other words, that the pressure increases as the space lessens, and diminishes as the space enlarges. 162. When a cavity to which the atmosphere has no access is enlarged, the density of the contained air is proportionably diminished. When any cavity is di- minished, the density of the contained air is proportionably increased. But if the atmosphere, meanwhile, have access to the cavity, it will by its influx or efflux tend to preserve the equilibrium of density and pressure between the air of the cavity and the external medium. These consequences are well known to ensue, from an al- ternate enlargement and diminution of capacity, during the working of an air pump, a condenser, or bellows. 163. In like manner the elevation of the receiver, R, enlarging the cavity within it unoccupied by water, causes the air to rush in through the orifice, O ; and the re- versal of the motion, reducing the cavity, causes the air to rush out through the same aperture. The bladder is so situated as to receive all the air that enters, and to supply all that is expelled. Hence when the receiver is lifted, the bladder is in- flated, and when lowered to its previous position, the bladder resumes its original dimensions. 164. Supposing the space, A, between the outside of the bladder and the inside of the receiver, to represent the space between the outside of the lungs and the inside of the thorax, the cavity of the bladder representing the cavities of the lungs, and the orifice, O, performing the part of the trachea and nostrils, the explanation, above given, will be as applicable to the apparatus by which nature enables us to breathe, as to that employed in the preceding illustration. EXPANSION OF ELASTIC FLUIDS. 165. Having by means of the preceding digression ex- plained the nature and extent of atmospheric pressure, I shall proceed to show the important influence exercised by it in all chemical processes in which elastic fluids are concerned. 166. It has been demonstrated (54) in illustrating the principle of Sanctorio's thermometer, that the bulk of the air in any space varies with the temperature. 167. It has been shown that the same effect may be produced by variations in atmospheric pressure. (115, 119, 120, 122.) 168. It follows that the volume of elastic fluids is in- versely as the pressure and directly as the heat. In other words, the less the pressure arid the greater the heat, the. larger their bulk ; and vice versa, the less the heat, and the greater the pressure, the less their bulk. 169. Agreeably to the observations of Dalton, Gay-Lussac, and Crich- ton, 1000 parts of atmospheric air, in rising from the temperature of 32 to 212, will expand so as to measure 1375 parts nearly, or, ^-g^th of the bulk which it would have at 32, for each degree of heat which it may re- ceive. CALORIC. 31 170. Having, therefore, any given bulk of dry air, 100 cubic inches for instance at 60, to find its bulk at any other temperature, suppose at 80, we must in the first place consider that 480 parts at 32 would at 60, adding one part for every degree above 32, be 508 parts ; and would by a proportionate increase, become at 80, 528 parts. But if 508 parts at 60 become 528 at 80, what will 100 parts at 60 become when heated to 80. 508 : 528 : : 100 : 103.9 171. It has been inferred by the same distinguished philosophers, that all aeriform substances, whether gases or vapours, are expanded by heat at the same rate- as dry atmospheric air, if they be not in contact with any vaporizable matter, in the liquid or solid state, which by vaporizing or con- densing may vary the result. Theory of Expansion. 172. The expansion of matter, whether solid, liquid, or aeriform, by an increase of temperature, may be thus explained. 173. In proportion as the temperature within any space is raised, there will be more caloric in the vicinity of the particles of any mass contained in the space. The more caloric in the vicinity of the particles, the more of it will combine with them ; and in proportion to the quantity of caloric thus combined, will they be actuated by that reciprocally repellent power, which, in proportion to its intensity, regulates their distance from each other. 174. There may be some analogy between the mode in which each ponderable atom is surrounded by the caloric which it attracts, and that in which the earth is surrounded by the atmosphere; and as in the latter case, so probably in the former, the density is inversely as the square of the dis- tance. 175. At a height at which the atmospheric pressure does not exceed a grain to the square inch, suppose it to be doubled, and supported at that in- creased pressure by a supply of air from some remote region ; is it not evident that a condensation would ensue in all the inferior strata of the atmosphere, until the pressure would be doubled throughout, so as to be- come at the terrestrial surface, 30 pounds, instead of the present pressure of 15 pounds? Yet the pressure at the point from which the change would be propagated would not exceed two grains per square inch. 176. In like manner, it may be presumed that the atmospheres of caloric are increased in quantity and density about their respective atoms, by a slight increase in the calorific tension of the external medium. Demonstration that Atmospheric Pressure opposes and limits Chemical Action, where Elastic Fluids are to be generated or evolved. Of Vaporization. 177. Water would boil at a lower temperature than 212, if the atmospheric pressure was lessened; for when it 32 IMPONDERABLE SUBSTANCES. has ceased to boil In the open air, it will begin to boil again in an exhausted receiver. Those who ascend mountains find that for every 530 feet of elevation, the boiling point is lowered one degree of Fahrenheit's thermometer. It is, in fact, lowered or raised rinnrth of a degree for every tenth of an inch of variation in the height of the mercury in the barometer. Ebullition from diminished Pressure. 178. The adjoining figure represents a vessel of water boiling within a receiver, in consequence of the diminution of pressure by exhaustion. Culinary Paradox. Ebullition by Cold. 179. A matrass, half full of water, be- ing heated until all the contained air is superseded by steam, the orifice is closed so as to be perfectly air-tight. The matrass is then supported upon its neck, in an in- verted position, by means of a circular block of wood. A partial condensation of the steam soon follows from the re- frigeration of that portion of the glass which is not in contact with the water. The pressure of the steam upon the liquid of course becomes less, and its boiling point is necessarily lowered. Hence it begins again to present all the phenomena of ebullition, and will continue boiling sometimes for nearly an hour. 180. By the application of ice, or of a sponge soaked in cold water, the ebullition is accelerated ; because the aqueous vapour which opposes it, is in that case more ra- pidly condensed ; but as the caloric is at the same time more rapidly ab- stracted from the water by the increased evolution of vapour to replace that which is condensed, the boiling will cease the sooner. CALORIC. 33 Improved Apparatus for showing the Culinary Paradox. 181. This figure illustrates a new and in- structive method of effecting ebullition by cold. 182. The apparatus consists principally of a glass matrass, with a neck of about three feet in length, tapering to an orifice of about a quarter of an inch in diameter. The bulb is bulged inwards in the part directly oppo- site the neck, so as to create a cavity capa- ble of holding any matter which it may be desirable to have situated therein. In addi- tion to the matrass, a receptacle holding a few pounds of mercury is requisite. The bulb of the matrass being rather less than half full of water, and this being heated to ebullition, the orifice should be closed by the finger, defended by a piece of gum-elas- tic, and depressed below the surface of the mercury; the whole being supported as re- presented in the figure. Under these cir- cumstances, the mercury rises as the tempe- rature of the water declines, indicating the consequent diminution of pressure within the bulb. Meanwhile, the decline of pressure lowering the boiling point of the water, the ebullition continues till the mercury rises in the neck nearly to the height of the mercury in the barometer. 183. By introducing into the cup formed by the bulging of the bulb, cold water, alcohol, ether, or ice, the refrigeration, the diminution of pressure, and the ebullition, are all simultaneously accelerated; since these results are reciprocally dependent on each other. Experimental Proof that some Liquids would be permanently aeriform, if Atmospheric Pressure were removed. 184. The power of certain liquids, common ether for instance, to assume in vacuo, at ordinary tempe- ratures, the aeriform state, in opposition even to the pressure of a column of mercury, may be shown by the following experiment. 185. A glass funnel is ground to fit air-tight into the neck of a glass decanter, so that the stem of the funnel may reach nearly to the bottom of the decan- ter, as represented in the adjoining cut. The decan- ter is filled with mercury, with the exception of a small portion of the neck, which is occupied by ether. The stem of the funnel is then introduced into the neck of the decanter, so as to be air-tight ; and the whole be- ing included in a receiver, the air is withdrawn by a pump. The ether converted into vapour will force the mercury to rise from the decanter, through the stem, into the wider part of the funnel. 186. Rationale. The attraction between the ponderable particles of the ether, and those of caloric, can be indulged only in opposition to the reci- procally repulsive power of the latter ; since one tends to rarefy the caloric, 5 34 IMPONDERABLE SUBSTANCES. the other to condense it into the limited space occupied by the ether. It follows that the caloric cannot combine with the ponderable matter beyond the point at which the repulsive power becomes equal to the attractive. But the repulsion exercised by the same number of particles of caloric will be greater as the space is less, and vice versa. The larger, therefore, the space occupied by the ponderable particles of the ether, the more caloric may combine with them, without rendering its reciprocally repulsive power paramount to its attraction for them. 187. The removal of atmospheric pressure, by allowing the ponderable particles to occupy a larger space, enables them to combine with that addi- tional quantity of caloric which is necessary to the aeriform state. 188. This explanation may, of course, be extended to the ebullition of other liquids in vacuo, at temperatures lower than those at which they boil in the air. It is obviously applicable to the two preceding illustra- tions. Boiling Point elevated by Pressure. 189. Into a small glass matrass, with a bulb of about an inch and a half in diameter and a neck of about a quarter of an inch in bore, in- troduce nearly half as much ether as would fill it. Closing the orifice with the thumb, hold the bulb over the flame of a spirit lamp, until the effort of the generated vapour to escape becomes difficult to resist. Removing the matrass to a sufficient distance from the lamp, lift the thumb from the orifice. The ether, previously qui- escent, will rise up in a foam, produced by the rapid extrication of its vapour. 190. This experiment may be performed with less risk, by plunging the matrass in hot water, instead of heating it by a lamp. 191. Having supplied a small flask with a quantity of mercury, sufficient to cover the bottom to about an inch in depth, let there be a glass tube so introduced through the neck, and luted air-tight, as to extend nearly an inch below the mercurial surface. If the flask thus prepared, be duly heated, the ether will be proportion ably vapourized, and the generated vapour pressing on the mercury, will cause a column of this metallic liquid to rise within the tube, and thus to in- dicate and measure the pressure. It is necessary to discontinue the heat, when the mercurial column ap- proaches the upper orifice of the tube, in order to pre- vent the metal from overflowing. High Pressure Boiler. (Page 35.) CALORIC. 35 High Pressure Boiler. 192. That the temperature of steam increases with the pressure, may be demonstrated by means of a small boiler, such as is represented in the opposite engraving. 193. A glass tube, of about five feet in height, and of half an inch in bore nearly, is secured into an aperture in a very strong iron boiler, so as to be air-tight, and so as to be concentric with the axis of the boiler. Within the boiler the tube descends in such manner as to pass through the water with which it is supplied, and to terminate close to the bottom, be- neath a small quantity of mercury purposely introduced. On the opposite side of the boiler, a tube, not visible in the engraving, descends into it. This tube consists of about two inches of a musket barrel, and is closed at bottom. The object of it is to contain some mercury, into which the bulb of a thermometer may be plunged for ascertaining the temperature. 194. When the fire has been applied during a sufficient time, the mercury will rise in the glass tube so as to be visible above the boiler ; and con- tinuing to rise during the application of the fire, it will be found that, with every sensible increment in its height, there will be a corresponding rise of the mercury in the thermometer. 1 95. In front of the tube, as represented in the figure, there may be ob- served a safety valve with a lever and weight for regulating the pressure. It has been found that, when the effort made by the steam to escape, in opposition to the valve thus loaded, is equal to about fifteen pounds for every square inch in the area of the aperture, the height of the column of mer- cury, C C, raised by the same pressure, is about equal to that of the co- lumn of this metal, usually supported by atmospheric pressure in the tube of a barometer. 196. Hence the boiler, under these circumstances, is conceived to sustain an unbalanced pressure equivalent to one atmosphere ; and for every addi- tional fifteen pounds per square inch, required upon the safety valve to re- strain the steam, the pressure of an atmosphere is alleged to be added. To give to steam at 212 degrees, or the boiling point, such an augmentation of power, a rise of 38 degrees is sufficient, making the temperature equal to 250 degrees. To produce a pressure of four atmospheres about 293 de- grees would be necessary. Eight atmospheres would require nearly 343 degrees. 197. When by means of the cock an escape of steam is allowed, a cor- responding decline of the temperature and pressure ensues. 198. If the steam, as it issues from the pipe, be received under a portion of water of known temperature and weight, the consequent accession of heat is surprisingly great, when contrasted with the accession of weight derived from the same source. It has in fact been ascertained that one measure of water, converted into aqueous vapour, will, by its condensa- tion, raise about ten measures of water in the liquid form one hundred degrees. Of the Incompetency of a Jet of High Steam to scald at a certain Distance from the Aperture. 199. Much attention has been excited by the observation, that the hands may be enveloped in a jet of vapour from a high pressure boiler without 36 IMPONDERABLE SUBSTANCES. inconvenience, at a certain distance from the aperture through which it Experimental Demonstration. 200. The fact that the hand may be immersed without injury in a jet of steam while issuing from a boiler, if not too near the aperture, experimentally demonstrated. 201. Rationale. Since the temperature, density, and pressure, which form the distinguishing attributes of high steam, cannot be sustained with- out confinement, steam ceases to be high steam as soon as it is liberated. Consequently, a jet from a high pressure boiler is essentially no more than a copious jet of aqueous vapour at the heat of boiling water. 202. The only distinguishing characteristic, derived from its previously superior temperature and density, is a greater velocity of efflux. Without any superiority of temperature, the high pressure jet is propelled in{o the atmosphere with a momentum, which cannot be given to low steam. Hence the rapid refrigeration to which the former is subjected, at a sufficient dis- tance from the place of its efflux to admit of an extensive diffusion in the atmosphere. Illustration of the Process by which Thermometers are supplied with the Liquids used in their construction. 203. A globe, with a long cylindrical neck, situated as in the preceding figure, and containing a small quantity of water, being subjected to the flame of a lamp, the water, by boiling, will soon fill the cavity of the globe and neck with steam. When this is accomplished, bubbles of air will cease to escape from the orifice of the neck through the water in the vase. 204. The apparatus being thus prepared, on removing the lamp, the water will quickly rush from the vase into the vacuity arising from the condensation of the steam within the globe. CALORIC. 37 Explosive Power of Steam. 205. If a glass bulb, hermetically sealed while containing a small quantity of water be suspend- ed by a wire over a lamp flame, an explosion soon follows, with a violence and noise which are sur- prising, when contrasted with the quantity of water by which they are occasioned. 206. Rationale. Supposing that the bulb were, in the first instance, merely filled with steam, without any water in the liquid form, the explana- tion of this phenomenon would be comprised in the theory of expansion, already suggested. (173.) In that case, the effort of the steam to enlarge itself, would be nearly in direct arithmetical proportion to the temperature ; but water being present in the li- quid form, while the expansive power of the steam, previously in existence, is increased, more steam is generated with a like increased power of expansion. It follows that the increments of heat being in arithmetical proportion, the explosive power of the confined vapour will increase geometrically, being actually doubled as often as the temperature is augmented 38. (196.) Interesting Experiments with respect to Vaporization under extreme Pres- sure, by M. Cagniard de la Tour, and Mr. Perkins. 207. Agreeably to some experiments performed by M. Cagniard de la Tour, in which liquids were exposed to heat in very stout tubes, vaporiza- tion was performed in a space which was to that previously occupied, Ether, as 2 to 1, producing a pressure of 33 atmos- pheres. Alcohol, as 3 to 1, producing a pressure of 119 atmos- pheres. Water, as 4 to 1, producing a pressure greater than that caused by the alcohol. In the case of 208. Mr. Perkins alleges that a small iron boiler of great strength may be heated red-hot while holding a portion of water, and that if, under these circumstances, an aperture be opened of \ of an inch in diameter, the steam will not escape, although upon a reduction of temperature, it will rush out with great violence. 209. It was inferred that the repulsion between the particles of the caloric in union with the water, and those in union with the metallic ring bounding the aper- ture, was paramount to the pressure tending to produce the expulsion of the steam. 210. I am unable to reconcile this experiment with one which I performed by heating to incandescence, in a forge fire, a tube of iron, of which the bore was less than i of an inch, while, by means of a cock, a communication with a high pressure boiler was made. Under these circumstances, the steam was not prevented from escaping through the pipe. 211. It appears to be sufficiently proved that the quantity of caloric combined with a given weight of steam is always the same, whatever may be its temperature; the sensible heat increasing and the latent heat diminishing as the density and pressure are augmented. Cold and Cloudiness arising from Rarefaction. 212. Incipient rarefaction in the air of a receiver is usually indicated by a cloud, which disappears when the exhaustion has proceeded beyond a certain point. A delicate thermometer placed in the receiver, shows that a decline of temperature JO IMPONDERABLE SUBSTANCES. accompanies this phenomenon. We may, therefore, infer that the cloud is the con- sequence of refrigeration. If the suggestions be correct which were made (Theory of Expansion, 175) respecting the mode in which caloric exists in atmospheres around the particles of ponderable matter, it will not be difficult to understand why aeriform fluids should absorb more caloric, in proportion as their consti- tuent particles are enabled, by a diminution of pressure, to become more remote. Hence, by rarefaction, the capacity of air is increased, and cold is produced, which condenses the aqueous vapour until its sensible heat is restored by an accession of caloric from the surrounding medium. (184.) Cold produced by the Palm Glass. 213. In forming the bulbs severally at the ends of the glass tube represented in this figure, one is furnished with a perforated pro- jecting beak. By warming the bulbs, and plunging the orifice of the beak into alcohol, a portion of this liquid enters, as the air within contracts in returning to its previous tempera- ture. The liquid, thus introduced, is to be boiled in the bulb which has no beak, until the whole cavity of the tube and of both bulbs, not occupied by liquid alcohol, is filled with its steam. While in this situation, the end of the beak is to be shortened and sealed, by sub- jecting it to the flame excited by a blowpipe. 214. As soon as the instrument becomes cold, the steam, which had filled the space vacant of liquid alcohol, condenses, and with the exception of a slight portion of vapour, which is always emitted by liquids when relieved from atmospheric pres- sure, a vacuum exists within the bulb. 215. The instrument, thus formed, has been called a palm glass; because the phe- nomenon which it exhibits is seen by grasping one of the bulbs, so as to bring it completely into contact with the palm of the hand. One of the bulbs being thus situated, and while surcharged with the alcohol, and held in the position represented in the figure, both the liquid and vapour are propelled from it into the other bulb. This phenomenon combines the characteristics of the differential thermometer, (69,) with those of the culinary paradox, (179,) being the joint effect of the expansion, and evolution of vapour, in one part of the apparatus, and its contraction and condensa- tion in another. The phenomena are precisely similar, whether we warm the lower bulb, or cool the upper one by means of ice. The motive for recurring to the expe- riment here is to state that, as soon as the last remnant of the liquid is forced from the bulb in the hand, a striking sensation of cold is experienced by the operator. 216. This cold has been attributed generally to an increase of the capacity of the residual vapour for caloric in consequence of its attenuation. The analogy is evi- dent between this phenomenon and that above described, as taking place in the re- ceiver of an air pump; in either case refrigeration results from a diminution of density. Cold consequent to relaxation of Pressure. 217. Cold is produced whether a diminution of density arise from relieving con- densed air from compression, or from subjecting air of the ordinary density to rare- faction. A cloud similar to that which has been described as arising in a receiver partially exhausted, may usually be observed in the neck of a bottle recently uncork- ed, in which a quantity of gas has been evolved in a state of condensation by a fer- menting liquor. CALORIC. 39 218. The apparatus represented in the annexed figure, shows the influence of relaxed pressure on the capacity of air for heat and moisture. 219. A glass vessel with a tubulure and a neck has an air thermometer fastened air-tight by means of a cork into the form- er, while a gum-elastic bag is tied upon the latter. Before closing the bulb, the inside should be moistened. Under these circumstances, if the bag, after due com- pression by the hand, be suddenly re- leased, a cloud will appear within the bulb, adequate, in the solar rays, to pro- duce prismatic colours. At the same time the thermometer will show that the compression is productive of warmth, the relaxation of cold. 220. The cloud which has been shown to arise (212,) in air suddenly rarefied, has been much insisted upon of late, by Mr. Espy, as illustrating a meteorological pro- cess, which he considers as the principal cause of rain storms. This induced me to make some experiments in order to elucidate this subject. 221. Large globes, each containing about a cubic foot of space, furnished with thermometers and hygrometers, were made to communicate, respectively, with re- servoirs of perfectly dry air, and of air replete with aqueous vapour.* The cold, ultimately acquired by any degree of rarefaction, appeared to be the same, whether the air was in the one state or the other; provided that the air, replete with aqueous vapour, was not in contact with liquid water in the vessel subjected to exhaustion. When water was present, in consequence of the formation of additional vapour, and a consequent absorption of caloric, the cold produced was nearly twice as great as when the air was not in contact with liquid water ; being nearly as 9 to 5. 222. Under the circumstances last mentioned, the hygrometer was motionless; whereas, when no liquid water was accessible, the space, although previously satu- rated with vapour, by the removal of a portion of it together with the air which is withdrawn by the exhaustion, acquires a capacity for more vapour; and hence the hygrometer, by an abstraction of one-third of the air, revolved more than sixty de- grees towards dryness. But when a smaller receiver (after being subjected to a diminution of pressure of about ten inches of mercury, so as to cause the index of the hygrometer to move about thirty-five degrees towards dryness) was surrounded by a freezing mixture, until a thermometer in the axis of the receiver stood at three degrees below freezing, the hygrometer revolved towards dampness, until it went about ten degrees beyond the point at which it rested when the process commenced. 223. It appears, therefore, that the dryness produced by the degree of rarefaction employed is more than counterbalanced by a freezing temperature. 224. As respects the heat imparted to the air above mentioned, the fact, that the ultimate refrigeration in the case of air replete with vapour, and in that of anhy- drous air, was equally great, and that when water was present the cold was greater in the damp vessel, led to the idea, that the heat arising under such circumstances could not have much efficacy in augmenting the buoyancy of an ascending column of air : but when, by an appropriate mechanism, the refrigeration was measured by the difference of pressure at the moment when the exhaustion was arrested, and when the thermometer had become stationary, it was found creteris paribus, that the reduction of pressure arising from cold was at least one-half greater in the anhy- drous air, than in the air replete with vapour. This difference seems to be owing to a loan of latent heat,made by the contained moisture, or transferred from the appa- * The hygrometers were constructed by means of the beard of the avena sengitiva, or wild oat, also called animated oat. 40 IMPONDERABLE SUBSTANCES. ratus by its intervention, which checks the refrigeration ; yet, ultimately, the whole of the moisture being converted into vapour, the aggregate refrigeration does not differ in the two cases. 225. Agreeably to Dalton's tables, at 70 the quantity of moisture in 31 grains or 100 cubic inches of air, is 551-lOOOths of a grain. The space allotted to this weight of vapour being doubled, it would remain uncondensed at 45 F., being associated with the same weight, but double the volume, of air; but at 32, notwithstanding the doubling of the space, only 356-lOOOths of a grain would remain in the aeriform state ; of course 551 356 = 195-lOOOths, or nearly 2-10ths of a grain, would be precipitated. 226. The latent heat given out by the condensation of this vapour, would heat, as 25 F. As air, at 32 F., expands l-480ths for each additional degree, the difference of bulk, arising from the heat received, as above calculated, would be 25-480ths, or l-19ths nearly. 227. When air, replete with aqueous vapour, was admitted into a receiver par- tially exhausted, and containing liquid water, a copious precipitation of moisture en- sued, and a rise of temperature greater than when perfectly dry air was allowed to enter a vessel containing rarefied air in the same state. In the instance first men- tioned, a portion of vapour arises into the place of that which is withdrawn during the partial exhaustion. Hence when the air, containing its full proportion of va- pour, enters, there is an excess of vapour which must precipitate, causing a cloud, and an evolution of latent heat from the aqueous particles previously in the aeriform state. As the enlargement of the space occupied by a sponge, allows, proportiona- bly, a larger quantity of any liquid to enter its cells, so any rarefaction of the air when in contact with water, consequent on increase of heat or diminution of pres- sure, permits a proportionably larger volume of vapour to associate itself with a given weight of the air. When, subsequently, by the afflux of wind replete with aqueous vapour, the density of the aggregate is increased, a portion of the vapour equivalent to the condensation must be condensed, giving out latent heat, excepting so far as the heat thus evolved, being retained by the air, raises the dew point. 228. Hence, whenever a diminution of density of the air inland causes an influx of sea air to restore the equilibrium, there may result a condensation of aqueous va- pour, and evolution of heat, tending to promote an ascending current. This process being followed by that which Mr. Espy has pointed out, of the transfer of heat from vapour to air, during its ascent to the region of the clouds, and consequent precipi- tation of moisture, is probably among the efficient causes of those wen-electrical rain storms, during which water from the Gulf of Mexico, or from the Atlantic, is trans- ferred to the soil of the United States. Of the Influence of the Atmosphere in promoting Evapora- tion. 229. It has been seen that by its pressure the atmo- sphere opposes vaporization; yet a free access of air is found indispensable in the desiccation of hay, or in the evaporation of water or other solvents. It was at one time generally conceived that evaporation resulted from an affinity between the liquid and the air, analogous to that between water and sugar, or alcohol and resin; but in consequence of the observations of several distinguished philosophers, a different view of this subject has been lat- terly entertained. It has in fact been ascertained that the quantity of aqueous vapour, in any space having sufficient access to liquid water, is always directly as the tempera- ture, whether there be a plenum or a vacuum, or whatever may be the density of the air simultaneously present. CALORIC. 41 230. It has been alleged that a current of atmospheric particles promotes evaporation, only by removing the ne- cessity to which the vapour would otherwise be exposed, of diffusing itself through the atmospheric interstices to a greater distance. 231. Nevertheless, it appears to me that the influence of a current of atmospheric air, in promoting evaporation, is greater than can be reasonably thus accounted for. 232. It is difficult to conceive that the elements of at- mospheric air should have no affinity for those of liquids; or that, if such affinity exist, it should not promote the process of evaporation. Nothing can be more certain than that evaporation is accelerated in proportion to the extent to which contact may be induced between the aeri- form and liquid particles. Hence when surfaces, moistened with such volatile liquids as sulphuret of carbon, or the more volatile ethers, are exposed to the wind, or to a blast, intense cold is produced by the accelerated evaporation. It is well known that the direction of the wind becomes evident from the sensation of coldness, experienced in that part of the wetted finger on which it blows. With the re- frigerating influence of a breeze, when the skin is moistened by perspiration, we are all familiar. 233. The processes of evaporation, and vaporization in the sense of ebullition, cannot be confounded in practice, however they may be identified agreeably to prevailing theories. In either case, heat is requisite, though much less is necessary in that of evaporation; but other things being equal, the process last mentioned, is accelerated in proportion to the extent of surface exposed to the air, while ebullition takes place in proportion to the surface exposed to the fire, without access of air. It only requires that the vapour generated should have an aperture sufficient to allow of its escape, without increase of pressure. Hence evaporating vessels are made broad and shallow, while boilers may be made deep with narrow openings. Cold produced by the Evaporation of Ether when accelerated by a Current of Air. 234. The cold, produced by evaporation accelerated by a current of air, may be advantageously shown by subject- ing a thermometer bulb simultaneously to a jet of ether, 6 42 IMPONDERABLE SUBSTANCES. and a blast from a bellows, so that the aerial and ethereal particles may be thoroughly mingled just before reaching the bulb. Water may be frozen in a bulb thus refrige- rated. 235. Agreeably to the principle above illustrated, (217) that when air is liberated from a state of compression, cold ensues, I have lately contrived a new mode of ex- hibiting the vaporization of ether, so as to freeze water on a more extensive scale, and on a much more striking manner than heretofore. Between the lower part of a very strong vessel of sheet iron, capable of holding 40 gallons, and the "hydrant" pipes by which our city is supplied with water, a communication is made by means of a pipe and cock, so as to be opened or closed at pleasure. The vessel is previous- ly filled with air, by allowing it to discharge any water which it may hold through a cock. Under these circumstances, on opening the communication with the hydrant pipes, the air within the vessel may be subjected to a pressure of more than one atmosphere. (154.) If by means of a suitable leaden pipe, furnished with a cock, and terminating with a capillary orifice, the air be allowed to blow into some ether and water contained in a thin capsule, the ether will be rapidly vaporized, and the water soon frozen. 236. In this experiment, in lieu of hydric (sulphuric) ether, we employ the new form of hyponitrous ether which I have lately discovered, the congelation will be more rapidly accomplished. 237. It will hereafter be shown, that, by analogous causes, when solid carbonic acid is thrown into ether, a refrigeration is produced by which mercury may be rapidly frozen. Definition of Vapour by Berzelius. 238. Berzelius objects to the use of the word vapour as implying a condensible aeriform fluid. He uses it in the sense in which English authors employ the word fog, or cloud. Vapour and steam were originally, and still are used in this sense, yet the fluid which is used to propel steam engines, and to which they owe their distinguishing name, can only consist of water in the aeriform state in which it is by the distinguished Swede designated as aqueous gas. Johnson defines steam to be the smoke or vapour of any thing hot and moist. Of course steam smoke and va- pour have in some cases been used synonymously. I have elsewhere mentioned that before Black's discoveries and inferences were published, atmospheric air was the only aeriform fluid whose existence was recognised. Hence the use of the words steam and vapour has grown with our knowledge, and consequently the names applied to visible steam or vapour have been extended to mean the invisible aeri- form fluids from which it is produced by refrigeration. I have some repugnance to designating by a common epithet, permanent gases, and the condensible elastic fluids produced from liquids above their boiling points. I do not see that any dis- advantage arises from the customary use of the word vapour to designate the latter. Of the Opponent Influence of Pressure on the Extrication of Gaseous Substances from a state of Combination. 239. When one of the ingredients of a solid or liquid is prone to assume the aeriform state, its extrication will be more or less easily effected, in proportion as the pressure of the air is diminished or increased. CALORIC. 43 Escape of Carbonic Acid from Carbonate of Lime subjected to an Acid, promoted by Exhaustion and checked by Condensation. 240. If a tall cylindrical jar, containing a car- bonate undergoing the action of an acid, be placed under a receiver, and the air withdrawn by an air pump, the effervescence will be augmented. But if, on the other hand, the same mixture be placed under a receiver, in which the pressure is increased by condensation, the effervescence will be dimi- nished. In the one case, the effort of the carbonic acid to assume the gaseous state is repressed ; in the other, facilitated. Hence the advantage of condensation in the process for manufacturing car- bonic acid water. Beyond an absorption of its own bulk of the gas, the affinity of the water is inadequate to subdue the tendency of the acid to the aeriform state; but when, by mechanical pressure, a great number of volumes of the gas are condensed into the space ordinarily occupied by one, the water combines with as large a volume of the condensed gas, as if there had been no con- densation. Improved Apparatus for showing the Influence of Pressure on Effervescence. 241. A cylindrical receiver, about 30 inches in height, and 3 inches in diameter, is supported on a wooden block, W, between upright iron rods, RR. each at the lower end, riveted to a plate of iron beneath the block, and, at the upper end, a screw cut and furnished with a nut. By means of these screws and nuts thus formed, and an intervening cross bar, B, a brass disk. D, is pressed upon the rim of the re- ceiver. The disk is so ground to fit to the rim of the glass, as that, with the aid of some beeswax duly softened by lard, an air-tight juncture may be made. In the middle of the disk there is an aperture, from which proceeds a stout tube, with a cock on each side, severally furnished with gallows screws, by means of which lead pipes may be made to communicate with an air pump on one side, and a con- denser on the other. The tube is also surmounted by a cock, into which a glass funnel is cemented. Before closing the receiver, some solid carbonate in pieces must be introduced so as to occupy about one-third of the cavity. For this purpose I have employed carbonate of ammonia, calcareous spar in fragments, and latterly clam shells. In either of these substances, carbonic acid and lime are the principal ingre- dients. The carbonate being introduced, and the disk fastened into its place, as re- presented in the figure, diluted muriatic acid may be added, by means of the funnel and cock, in quantity sufficient to cover the carbonate. 242. In consequence of the superior affinity of chlorine for the calcium, and of hy- drogen for the oxygen, (in the oxide of calcium or lime) the carbonic acid is expelled in the gaseous form, causing a perceptible effervescence or foaming of the liquid. If, under these circumstances, by means of the air pump, the atmospheric pressure within the receiver be lessened, the effervescence increases strikingly. On the other hand, if, by closing the communication with the air pump, and opening that with the condenser while this is in operation, the pressure be increased, it will be seen that the effervescence is diminished proportionably. 243. This experiment is much facilitated by the employment of an air pump, which I have contrived, by which we can either exhaust or condense at pleasure. 244. Agreeably to experiments performed by Faraday, when the reaction between an acid and a carbonate is made to take place in a stout tube hermetically sealed, the acid may be separated in the liquid form. According to the more recent obser- vations of Thilorier, this result has been attained upon a large scale, and one por- tion of the resulting liquid has been found to be partially frozen, by the caloric ab- stracted by the vaporization of the other portion. 44 IMPONDERABLE SUBSTANCES. 245. Thilorier's process, as improved by Mitchell and others, will be hereafter il- lustrated and explained. 246. By analogous means various substances, naturally gaseous, have been liquefied by Faraday, as will be mentioned in treating of those substances. 247. All the cases of liquefaction alluded to, are referable to the law that the power of any matter to pass to the aeriform state is, ceteris paribus, less in proportion as the pressure is greater. Of the Screw Rod and Plate Frame, employed in the preceding and many other Experiments. 248. The means by which the glass receiver, employed in the preceding experi- ment, is upheld and rendered air-tight by the rods, R R, the wooden block, W, the bar, B, and circular plate or disk, D, is one to which I shall resort frequently in the course of my experiments. Hence, to avoid unnecessary recurrence to analogous description, I shall in future designate as a screw rod and plate frame, that portion of the apparatus above described, which consists of the block, bar, plate, and screw rods* 249. The glass in this case is made quite true by grinding on a large lap wheel, such as is employed by lapidaries. The same objectls effected in the case of brass plates without grinding, by turning them in a lathe with a slide rest, and by a tool with a fine pyramidal point. OF CAPACITIES FOR HEAT, OR SPECIFIC HEAT. 250. The power of equal weights of different substances, at the same temperature, in cooling or warming a liquid at a temperature different from their own, will be found very unequal. Thus the effect of a given weight of water being 1000, the effect of the like weight of glass will be 137, of copper 94, tin 51, lead 29, iron 110, gold 29, pla- tinum 31, zinc 92, silver 55. If equal weights of water and mercury, at different temperatures, be mixed, the effect on the water will be no greater than if, instead of the mer- cury, Trth of its weight of water, at the same temperature as the mercury, had been added; and it takes twice as much mercury by measure as of water heated to the same point to have the same influence. 251. The term specific heat is usually employed to de- signate the quantity of caloric in a body in proportion to its weight or bulk, as specific gravity is used to convey an idea of weight compared with bulk. 252. In the process above described, the specific heats of substances are found in order to estimate their capaci- ties; the one being necessarily as the other, and the same series of numbers expressive of either. * Modification of the screw rod and plate frame are represented in the engraving referred to page 28. (153.) CALORIC. 45 Apparatus for illustrating Capacities for Heat. T 253. Let the vessels A, B, and C, be supplied with water through the tube, T, which communicates with each of them by a horizontal channel in the wooden block. The water will rise to the same level in all. Of course the resistance made by the water in each vessel to the entrance of more of this liquid will be the same, and will be measured by the height of the column of water in the tube, T. Hence, if the height of this column were made the index of the quantity received by each vessel, it would lead to an impression that they had all received the same quantity. But it must be obvious that the quantities severally received will be as different as are their horizontal areas. Of course we must not assume the resistance, ex- erted by the water within the vessels against a further accession of water from the tube, as any evidence of an equality in the portions previously received by them. 254. In like manner the height of the mercury in the thermometer shows the resistance which substances, whose temperature it measures, are making to any further accession of caloric ; but it does not indicate the quantities, respectively received by them, in attaining the temperature in question. This varies, in them, in proportion to their attraction for this self- repellent fluid ; as the quantities of water received by the vessels, A, B, C, are varied in the ratio of their respective areas. 255. Rationale. It may be conjectured that this diversity in the power of substances, equally hot or cold, in influencing temperature, is due to a difference in their capacity to attract caloric, in consequence of which it probably forms denser atmospheres about the atoms of some substances, than it does about those of others. 256. An analogy has already been suggested to exist between the man- ner in which these calorific atmospheres surround atoms, and that in which the earth is surrounded by the air ; and also the mode has been suggested in which changes of temperature in the external medium would operate upon the density of such atmospheres. Supposing these preliminary sugges- tions correct, it would follow that the quantity of caloric absorbed or given out at each exterior change of temperature, by any one congeries of atoms, would be to that absorbed or given out by any other congeries, as the pre- vious condensation of caloric in the one, is to its previous condensation in the other. (173, 174, 175, 176.)* * A notice of the doctrine of Petit and Dulong that the capacities of all elemen- tary atoms for heat are the same, will be deferred till 1 have treated of atomic pro- portions. 46 IMPONDERABLE SUBSTANCES. Of the Specific Heat of Gaseous Bodies. 257. It was suggested by Lambert and Pictet, and the suggestion was after- wards sanctioned by Dalton, that space may have a capacity for caloric. Consistently with this idea the quantity of caloric in a given space should always be the same whatever may be the gaseous fluid occupied by it. This is consistent with the fact that all the gases have the same capacity for heat, and all undergo a like expansion, in consequence of a like increase of temperature. Agreeably to this view of the case, the cold produced by rarefaction, as in the experiment with the exhausted receiver (212) or the palm glass, (215,) the heat consequent to the compression of air (219) arises from the caloric in the air or vapour, being too little for the space allotted to the air in one case, and too great for that allotted in the other. This idea seems to have been abandoned, in consequence of an experiment performed by Gay Lussac. This eminent chemist having made a Torri- cellian vacuum within a tall cylindrical glass receiver, about 3 inches in diameter and 39 in height, found that when the mercury employed was made to rise or sink in the vacant space so as alternately to enlarge or di- minish it, no consequent variation of the temperature took place, since a delicate air thermometer, of which the bulb was included, indicated no change. It appeared, nevertheless, that when a minute quantity of air was admitted, any increase or diminution of the void space, consequent to the rise or fall of the mercury, was as productive, as the same thermometer showed, of a corresponding increase, or diminution, of sensible heat. Hence it has been inferred that a perfectly void space has no capacity for heat, the changes of temperature, consequent to the rarefaction or conden- sation of aeriform fluids, being altogether caused by corresponding changes in the capacity of those fluids for caloric. But as a perfect vacuum must liberate heat with perfect facility, it appears to me that the caloric should be absorbed by the mercury as rapidly as this metal could be made to en- croach upon the space occupied by the calorific particles, and that, conse- quently, no palpable condensation of them could be effected by the above described process resorted to by Gay Lussac. 258. Admitting that, for equal weights, the specific heat of air is seven times as great as that of mercury, that of space being the same by the premises, there could not have been a capacity greater than that of about 200 grains of the metal, whereas a very small stratum of this metal, equal to one-fourth of an inch, would, in the apparatus employed, amount to more than a pound. 259. The following experiments appear to me to be irreconcilable with the idea that the heat acquired by air entering a space does not arise from the specific heat of the space. When a receiver was exhausted so as to reduce the interior pressure to one-fourth of that of the atmosphere, and one-fourth was suddenly admitted, so as to lower the mercurial column in a gauge from about 22^ inches to 15 inches, heat was produced ; and however the ratio of the entering air to the residual portion was varied, still there was a similar result. 260. When the cavity of the receiver was supplied with the vapour of ether, or with that of water, so as to form, according to the Daltonian hy- pothesis, a vacuum for the admitted air, still heat was produced by the lat- ter, however small might be the quantity, or rapid the readmission. When the receiver was exhausted, until the tension was less than that of aqueous vapour at the existing temperature, so as to cause the water to boil, as in the Cryophorus, or Leslie's experiment, still the entrance of T ^- of the quantity requisite to fill the receiver caused the thermometer to rise a tenth CALORIC. 47 of a degree. An alternate motion of the key of the cock, through one-fourth of a circle, within one-third of a second of time, was adequate to produce the change last mentioned. 261. The fact, that heat is produced, when to air, rarefied to one-fourth of the atmospheric density, another fourth is added, seems to me to be irre- concilable with the idea, that this result arises from the compression of the portion of air previously occupying the cavity, since the entering air must be as much expanded as the residual portion is condensed. 262. As, agreeably to Dalton, a cavity occupied by a vapour acts as a vacuum to any air which may be introduced, I infer that when a receiver, after being supplied with ether or water, is exhausted so as to remove all the air, and leave nothing besides aqueous or ethereal vapour, the heat, ac- quired by air admitted, cannot be ascribed, consistently, to the condensa- tion of the vapour. 263. It was ascertained by De la Rive and Marcet, that when the bulb of a thermometer is subjected to a jet of air while entering an exhausted receiver, that the instrument shows that refrigeration takes place. But if the jet be allowed to continue,' a rise of temperature ensues. Hence it was inferred by them, that in the first instance there is refrigeration, and a con- sequent absorption of caloric ; and subsequently an evolution of this prin- ciple, in consequence of the condensation of the air, which at the first moment of its influx, had been refrigerated. It appears to me, nevertheless, that in my experiments above described, the effect upon the thermometer was too rapid, and the quantity of the entering air too minute, to allow it to be refrigerated by rarefaction in the first place, and yet afterwards to be so much condensed as to become warm by the evolution of caloric. OF THE SLOW COMMUN [CATION OF HEAT, COMPRISING THE CONDUCTING PROCESS AND CIRCULATION. Of the Conducting Process in Solids. 264. It is well known that if one end of a piece of metallic wire, as a common pin for instance, be held in a candle flame, the other end soon becomes too hot for the fingers. It is also known that the heated irons, used in soldering and other processes in the arts, have usually wooden handles, which do not become unpleasantly warm, when the irons within them are hot enough to blister the hands. This inferior power of wood in conducting heat is also well exemplified by the handles of silver tea-pots, which are sometimes altogether of wood; in other in- stances principally of metal, small portions of wood inter- vening. In either case, the facility with which the heat is propagated in the comparatively thin metallic socket, is strongly contrasted with the difficulty which it experiences in permeating the wood. 265. An inferiority of conducting power, when com- pared with metals, is also displayed by common bone, whalebone, ivory, porcelain, and especially glass. 48 IMPONDERABLE SUBSTANCES. Inequality of Conducting Power, experimentally illustrated. 266. Let there be four rods, severally of metal, wood, glass, and whalebone, each cemented into a ball of sealing-wax. Let each rod, at the end which is not cemented to the wax, be successively exposed to the flame excited by a blow pipe. It will be found, that the metal becomes quickly heat- ed throughout, so as to fall off from the wax; but the wood or whalebone may be destroyed, and the glass bent by the igni- tion, very near to the wax, without melting it so as to liberate them. Additional Illustration. 267. The following method of illustrat- ing the diversity of conducting power, pos- sessed by different substances, has been suggested by an analogous process described in Silliman's Chemistry. 268. Rods similar in diameter and length, and consisting severally of lead, tin, iron, copper, wood, and ivory, are made to pass from side to side, through a vessel of sheet copper, in the shape of an oblong parallelepiped. Each rod extends on one of the sides, to an equal distance beyond the ves- sel. By these means, when the vessel is filled with boiling water, equal portions of each rod being situated within the boiler, they are all exposed to an equal degree of heat. It is presumed that under these circumstances the conducting power will be nearly in the inverse ratio of the time necessary to communicate to the equidistant ends of the rods, a heat adequate to cause the ignition of similar pieces of phosphorus, simultaneously placed upon them, before the application of the boiling water. Rationale of the Fracture of Glass or Porcelain by Heat. 269. The fracture of glass or porcelain, exposed to fire, is the conse- quence of an inferior conducting power; as the heat is not distributed with quickness enough to produce a uniform expansion. Hence glass is as liable to crack by heal, in proportion as it is thinner. It may be divided by a heated iron, by a string steeped in oil of turpentine and inflamed, or by the heat generated by friction. (322, &c.) Of the Conducting Power of various Metals. 270. Metals are by far the best conductors of caloric. There are, how- ever, scarcely two that conduct it equally well. 271. Despretz has ascertained by exact experiments, that the conduct- ing power of the following metals is in the ratio of the subjoined numbers. Gold, - - " 1000.0 Silver, 973.0 Copper, - 898.0 Platinum, - 381.0 Iron, - 374.3 Zinc, 363.0 CALORIC. 49 Tin, Lead, 303.9 179.6 Explanation of the Process by which Heat is supposed to be communi- cated in Solids. 272. I conceive that in solids, the stratum of atoms forming the surface first exposed to the heat, combining with an excess of this principle, divides it with the next stratum. The caloric received by the second stratum, is in the next place divided between the second and third stratum. In the mean lime the first stratum has received an additional supply of caloric, which passes to the second and third stratum as in the first instance; while the quantity, at first received by them, is penetrating further into the mass. 273. It is I trust easy to conceive that, by the process thus suggested, ca- loric may find its way throughout any body, for the particles of which it may have sufficient affinity. Probably the superior conducting power of metals is due in great measure to a proportionably energetic affinity for caloric. 274. The conjectures, which I ventured to advance respecting the mode in which caloric may exist in atmospheres about atoms, seem to be pecu- liarly applicable to the case of metals, on account of their great expansi- bility by heat, and susceptibility of contraction by cold. (174.) 275. If caloric be not interposed in a dense repulsive atmosphere between metallic atoms, how can its removal cause that approximation of those atoms towards each other, without which the diminution of bulk invariably conse- quent to refrigeration could not ensue? Liquids almost destitute of Conducting Power. 276. That liquids are almost devoid of power to conduct heat, is proved by the inflammation of ether over the bulb of an air thermometer, protected only by a thin stratum of water. 277. The inflammation of ether upon the sur- face of water, as represented in this figure, does not cause any movement in the liquid included in the bore of the air thermometer at L, although the bulb is within a quarter of an inch of the flame. Yet the thermometer may be so sensi- tive, that touching the bulb, while under water, with the fingers, may cause a very perceptible indication of increased temperature. By placing the sliding index, I, directly opposite the end of the column of liquid in the stem of the thermo- meter, before the ether is inflamed, it may be ac- curately discovered whether the heat of the flame causes any movement in it. 50 IMPONDERABLE SUBSTANCES. H Communication of Caloric by Circulation. 278. That caloric cannot be communicated in liquids, unless it be so ap- plied as to cause a circulation of the particles, is demonstrated by the following experiment. 279. A glass jar, about 30 inches in height, is supplied with as much water as will rise in it within a few inches of the brim. By means of a tube descending to the bottom, a small quantity of blue colouring matter is introduced below the colourless water so as to form a stratum as represented at A, in the engraving. A stratum, differently coloured, is formed in the upper part of the vessel, as represented at B. A tin cap, supporting a hollow tin cylinder, closed at bottom, and about an inch less in diameter than the jar, is next placed as it is seen in the engraving, so that the cylinder may be concentric with the jar, and descend about 3 or 4 inches into the water. 280. The apparatus being thus pre- pared, if an iron heater, H, while red- hot, be placed within the tin cylinder, the coloured water, about it, soon boils ; yet neither of the coloured strata inter- mingles with the intermediate colourless mass; and on sliding the finger up- wards, while in contact with the glass, the heat will be found to have penetrated only a very small distance below the tin cylinder. But if the ring, R, be placed, while red-hot, upon the iron stand which surrounds the jar at S S, the portion of the liquid coloured blue, being opposite to the ring, will rise until it encounters the warmer, and of course lighter, particles, which have been in contact with the tin cylinder. Here its progress upwards is arrested; and, in consequence of the diversity of the colours, a well defined line of sepa- ration becomes conspicuous. 281. The phenomena of this interest- ing experiment may be thus explained. 282. If the upper portion of a vessel, 1 containing a fluid, be heated exclusive- ly, the neighbouring particles of the fluid being rendered lighter by expan- R sion, are more indisposed, than before, to descend from their position. But if the particles, forming the inferior strata of the fluid in the same vessel-, be rendered warmer than those above them, their consequent expansion and CALORIC. 51 diminution of specific gravity causes them to give place to particles above them, which not being as warm, are heavier. Hence heat must be ap- plied principally to the lower part of the vessel, in order to occasion a uni- form rise of temperature in a contained fluid. 283. This statement is equally true, whether the fluid be aeriform or liquid, excepting that in the case of aeriform fluids, the influence of pres- sure on their elasticity 'may sometimes co-operate with, and at others op- pose, the influence of temperature. Experimental Illustration of the Process by which Caloric is distributed in a Liquid until it boils. 284. On the first application of heat to the bottom of a vessel contain- ing cold water, the particles in con- tact with the bottom are heated and expanded, and consequently become lighter than those above them. They rise therefore, giving an opportunity to other particles to be heated and to rise in their turn. The particles which were first heated, are soon comparatively colder than those by which they were displaced, and, de- scending to their primitive situation, are again made to rise by additional heat and enlargement of their bulk. Thus the temperatures reversing the situations, and the situations the tem- peratures, an incessant circulation is maintained, so long as any one por- tion of the liquid is cooler than another, or in other words, till ebul- lition takes place; previously to which every particle must have combined with as much caloric as it can receive, without being converted into steam. 285. The manner in which caloric is distributed throughout liquids by circulation, as above described, is illustrated advantageously by an experi- ment contrived by Rumford, who first gave to the process the attention which it deserves. 286. Into a glass nearly full of water, as represented by the foregoing figure, small pieces of amber are introduced, which are in specific gravity so nearly equal to water, as to be little influenced by gravitation.* The lowermost part of the vessel being subjected to heat while thus prepared, the pieces of amber are seen rising vertically in its axis, and after they reach the surface of the liquid, moving towards the sides, where the vessel is colder from the influence of the external air. Having reached the sides of the vessel, they sink to the bottom, whence they are again made to rise as before. While one set of the pieces of amber are at the bottom of the liquid, some are at the top, and others at intermediate situations ; thus de- * As amber is rather heavier than water, it is expedient to add some sulphate of soda* to increase the specific gravity of the liquid. 52 IMPONDERABLE SUBSTANCES. monstraling the movements by which an equalization of temperature is ac- complished in liquids. 287. When the boiling point is almost attained, the particles being near- ly of the same temperature, the circulation is retarded. Under these cir- cumstances, the portions of liquid which are in contact with the heated sur- face of the boiler are converted into steam, before, they can be succeeded by others ; but the steam thus produced cannot rise far before it is con- densed. Hence the vibration and singing sound which is at this time ob- served. 288. According to an observation of Gay-Lussac, water boils in metal- lic vessels at a temperature nearly two and a half degrees lower than in those of earthenware. QUICK COMMUNICATION OF HEAT, OR RADIATION. 289. It must be evident that the heat which we receive from a fire in opposition to the draught, reaches us nei- ther by the conducting process nor by circulation. Actual contact is evidently indispensable to the passage of heat in either of these modes. The aeriform matter which is in contact with the embers, or the blaze of a fire, forms part of a current which tends rapidly towards the flue, as must be evident from the celerity with which the sparks which accompany it are propelled. The rapidity with which the aerial particles, heated by the fire, are thus carried up the chimney, far exceeds that with which caloric can be com- municated, in the opposite direction, either by the conduct- ing process or by circulation. 290. The caloric received from a fire under the circum- stances above mentioned, and which is analogous to that by means of which the culinary operations of toasting and roasting are accomplished, is called radiant caloric, or more usually, radiant heat. It has been called radiant, because it appears "to emanate in radii or rays from every hot or even warm body, as light emanates from luminous bodies. 291. Radiant heat resembles light also in its susceptibi- lity of being reflected by bright metallic surfaces; in which case it obeys the same laws as light, and is of course lia- ble, in like manner, to be collected into a focus by concave mirrors. Phosphorus ignited by Radiant Heat. (Page 53.) CALORIC. 53 Model for illustrating the Operation of Concave Mirrors. 292. The object of the model represented by this diagram, is to explain the mode in which two mirrors operate in collecting the rays of radiant heat emitted from one focus, and in concentrating them in another. 293. The caloric emitted by a heated body in the focus of the mirror, A, would pass off in radii or rays, lessening in intensity as the space into which they pass enlarges ; or, in other words, as the squares of the dis- tances. But those rays which are arrested by the mirror, are reflected from it in directions parallel to its axis.* Being thus corrected of their divergency, they may be received, without any other loss than such as arises from mechanical imperfections, by the other mirror, which should be so placed that the axis of the two mirrors may be coincident ; or, in other words, so that a line drawn through their centres, from A to B, may at the same time pass through their foci, represented by the little balls supported by the wires, W W. 294. The second mirror, B, reflects to its focus the rays which reach it from the first; for it is the property of a mirror, duly concave, to render parallel the divergent rays received from its focus, and to cause the parallel rays which it intercepts to become convergent, so as to meet in its focus. 295. The strings in the model are intended to represent the paths in which the rays move, whether divergent, parallel, or convergent. Phosphorus ignited at the distance of sixty feet by an incandescent Iron Ball. 296. The opposite engraving represents the mirrors which I employ in the ignition of phosphorus and lighting a candle by an incandescent iron ball. I have produced this result at sixty feet, and it might be always ef- fected at that distance, were it not for the difficulty of adjusting the foci with sufficient accuracy and expedition. I once ascertained that a mercurial thermometer, when at the distance last mentioned, rose to 110 degrees of Fahrenheit. 297. A tallow candle is so situated, that its wick, previously imbued with phosphorus, may be in the fpcus of one of the mirrors. A lamp being similarly situated with respect to the other mirror, it will be easy, by re- ceiving the focal image of the flame on any small screen, so to alter the arrangement, as to cause this image to fall upon the phosphorus. This being effected, the screen, S, placed between the mirrors, is lowered so as The axis of a mirror is in a line drawn from its centre through its true focus. 54 IMPONDERABLE SUBSTANCES. to intercept the rays. The iron ball being rendered white-hot is now sub- stituted for the lamp, and the screen being lifted, the phosphorus takes fire and the candle is lighted. Of the Diversity of Radiating Power in Metals, Wood, Charcoal, Glass, Pottery, fyc. Diversity of Radiating Power experimentally illustrated. 298. At M, (see figure,) a parabolic mirror is represented. At B is a square glass bottle, one side of which is covered with tin foil, and another so smoked by means of a lamp as to be covered with carbon. Be- tween the bottle and mirror, and in the focus of the latter, there is a bulb of a differential thermometer, protected from receiving any rays directly from the bottle by a small metallic disk. The bottle being filled with boil- ing water, it will be found that the temperature in the focus, as indicated by the thermometer, is greatest when the blackened surface is opposite to the mirror, and least when the tin foil is so situated ; the effect of the naked glass being greater than the one, and less than the other. 299. The worst radiators are the best rejectors, and the best radiators are the worst reflectors ; since the arrangement of particles ivhich is fa- vourable for radiation is unfavourable for reflection, and vice versa. 300. A polished brass andiron does not become hot when exposed from morning till night to a fire, so near that the hand placed on it is scorched intolerably in a few seconds. Fire places should be constructed of a form and materials to favour radiation: flues, of materials to favour the con- ducting process. To preserve heat in air or to refrigerate in water, vessels should be made of bright metal. In the latter case, the brightness is bene- ficial, only because the surface cannot be bright without being clean. If soiled, its communication with the liquid would be impeded. 301. Rationale. Metals appear to consist of particles so united with each other, or with caloric, as to leave no pores through which radiant caloric can be projected. Hence the only portion of any metallic mass which can yield up its rays by radiation is the external stratum. CALORIC. 55 302. On the other hand, from its porosity, and probably also from its not retaining caloric within its pores tenaciously as an ingredient in its compo- sition, charcoal opposes but little obstruction to the passage of that subtile principle, when in the radiant form ; and hence its particles may all be simultaneously engaged in radiating any excess of this principle with which a feeble affinity may have caused them to be transiently united, or in re- ceiving the rays emitted by any heated body, to the emanations from which they may have been exposed. We may account in like manner for the great radiating power of earthenware and wood. 303. For the same reason that calorific rays cannot be projected from the interior of a metal, they cannot enter it when projected against it from without. On the contrary, they are repelled with such force as to be re- flected without any perceptible diminution of velocity. Hence the superior efficacy of metallic reflectors. 304. It would seem as if the calorific particles which are condensed be- tween those of the metal, repel any other particles of their own nature which may radiate towards the metallic superficies, before actual contact ensues; otherwise, on account of mechanical imperfection, easily discernible with the aid of a microscope, mirrors could not be as efficacious as they are found to be in concentrating radiant heat. Their influence, in this respect, seems to result from the excellence of their general contour, and is not pro- portionably impaired by numberless minute imperfections. Radiation of Cold. 305. A thermometer placed in the focus of a mirror indicates a decline of temperature, in consequence of a mass of ice or snow being placed before it in the situation occupied by the bottle in the preceding figure. This change of temperature has been considered as demonstrating the radiation, and consequently the materiality of cold. For since the transfer of heat by radiation has been adduced as a proof of the existence of a material cause of heat, it is alleged that the transmission of cold by the same pro- cess ought to be admitted as equally good evidence of a material cause of cold. 306. The following is the explanation which I give of this phenomenon, agreeably to the opinion that cold is diminished heat. 307. I suppose that caloric exists throughout the sublunary creation, as an atmosphere held to the earth by the general attraction of all the matter in it, being in part combined with bodies in proportion to their affinities or capacities for it, and partly free. The particles of the free caloric I sup- pose incessantly to exert a self-repellent power, which increases with its density, as in the case of aeriform fluids. The repulsive power of caloric being in the ratio of the quantity, it follows that either a diminution or in- crease of temperature in any spot must equally produce a movement in the calorific particles ; in the one case from the spot which sustains the change, in the other towards it. 308. Supposing the surface of a mirror to be subjected to the influence of a space in which a diminution of temperature has been produced, the rows of calorific particles between the mirror and the space will move into the space. The removal of one set of the calorific particles from the surface of the mirror, must make room for another set to flow into the situations thus vacated. The curvature of the surface of the mirror renders it more easy for those particles to succeed which lie in the direction of the focus. 56 IMPONDERABLE SUBSTANCES. Of the Observations and Apparatus of Melloni. 309. By means of a thermo-electric pile, and a galvanoscope or multi- plier, of extreme delicacy, Melloni has lately ascertained some interesting properties of heat-producing rays, which serve to show a marked difference, and, at the same time, a great analogy between them and the rays of light. 310. Let there be provided three transparent plates, severally of alum, rock salt, and rock crystal or glass, each about an eighth or tenth of an inch thick; it will be found that the effect of the transmitted rays upon the pile, when unimpeded, being 30, that which takes place during the inter- position of the rock salt, will be 28, during the interposition of the rock crystal 15 or 16 ; while during the interposition of the alum the effect will only be two or three. 311. The effect of interposing a plate of smoky rock crystal, will, under the same circumstances, be equal to 14 or 15. 312. In other words, out of 30 parts, rock salt intercepts two parfs of the influence of the radiant heat; rock crystal, whether smoky or clear, in- tercepts about half; while alum, or glass, intercepts nearly the whole. 313. If, in like manner, two pairs of plates be employed, one pair formed of a pane of green glass (impermeable to red rays,) and a plate of alum ; the other pair formed of a pane of perfectly opake black glass, coupled with a plate of rock salt, it will be found that the first mentioned pair in- tercepts the calorific radiation entirely, while the other permits nearly one- third as much to pass, as when not interposed. 314. Hence it appears, that bodies, quite permeable by light, may en- tirely intercept radiant heat, while others, impermeable by light, allow the passage of radiant heat. Melloni designates the former as athermane, the latter as diathermane bodies. 315. It follows that permeability to heat-producing rays is not to be confounded with transparency. 316. Radiant heat has been found by Melloni to vary in its power of permeating bodies, according to the source from which it proceeds, and the media through which it may have passed. After passing through nitric acid, more will pass through alum than if received directly from the source. 317. Moreover certain media have, with respect to calorific rays, an in- fluence analogous to that which coloured media have with respect to light, in allowing some rays to pass, while others are arrested. 318. This property of the diathermane bodies, is called diathermansie. Rock salt seems to be a diathermane body, devoid of diathermansie. The last mentioned property lessens as the body is thinner, and may, as in the case of coloured media, be rendered null by an extreme tenuity. 319. The non-luminous calorific rays have been ascertained by Melloni, to be susceptible of refractions analogous to those of light. When the thermo-electric pile is so situated as that the rays of heat cannot directly reach it, by interposing a prism of rock salt, having a refracting angle of 60, the rays will be made to reach the pile. 320. From experiments performed by Prof. Forbes, of Edinburg, with the aid of Melloni's thermoscope, above alluded to, it appears that radiant heat, unaccompanied by light-producing rays, is susceptible of polariza- tion. Respecting this fact, some further mention will be made in treating of the polarization of light. CALORIC. 57 MEANS OF PRODUCING HEAT, OR RENDERING CALORIC SENSIBLE. Of the Solar Rays as a Source of Heat. 321. Of all the natural sources of heat, the sun is ob- viously the most prolific. 322. The solar rays may be collected into a focus either by the refracting influence of glasses or the reflecting power of mirrors. They may be converged by reflection, in a mode analogous to that illustrated in the case of radiant heat. 323. The glasses employed for concentrating light are called lenses from their shape, which is that of a double convex lens. 324. As the intensity of the heat produced by the solar beams is in proportion to the quantity of them which may be collected upon any given spot, there appears to be no limit to the degree of heat producible by their concentra- tion, excepting that arising from the difficulty of making lenses sufficiently large and free from defect, or of associ- ating mirrors sufficiently numerous and well arranged. 325. Until lately, scarcely any occurrence of antiquity appeared more unaccountable than the destruction of the Roman ships, which Archimedes is alleged to have accom- plished, by concentrating upon them the rays of the sun. Nevertheless, of this wonderful feat, Buffon seems to have discovered the means. Having arranged a number of plane mirrors so as to concur in reflecting the solar image upon the same spot, he was enabled to fuse lead at a distance of 140 feet. This contrivance resembles that which Ar- chimedes employed, if we may judge from the accounts which have been given of the latter. Previously to the employment of pure oxygen gas, the hydro-oxygen blow- pipe, and voltaic electricity, there was no known mode of rivalling the heat produced by large burning-glasses and mirrors. Sensible Heat evolved by Electricity. 326. The power of lightning to produce ignition is dis- played by the conflagration of ships and barns, in con- sequence of the ignition of cotton, hay, or other combus- tibles. The power of the electric spark to ignite an inflam- 8 58 IMPONDERABLE SUBSTANCES. mable gaseous mixture is agreeably illustrated, by means of the apparatus described in the following article. Application of an Electrophorus to the Ignition of Hydrogen Gas, generated in a Self- regulating Reservoir. 327. In order that the interior of this apparatus may be described, (see fig. be- low) the side of the box, B, below the reservoir, R, is supposed to be removed. On the bottom of the box is a square metallic dish covered by a stratum of sealing wax. The metallic plate, D, is supported behind by a glass rod, cemented to a socket soldered to a hinge. Upon this hinge, like the lid of a trunk, the plate moves freely, while connected with the lever, L, by a silken cord. The lever, L, is attached to the key of the cock, C ; so that opening the cock causes the plate to rise, and touch the knob, n, of the insulated wire. This wire terminates just before the orifice of the tube, t, proceeding from the cock, and about one-eighth of an inch from another wire, supported upon that tube. 328. The glass reservoir, R, receives into its open neck, the tapering part of a glass vessel, V, which is so proportioned, and fitted to the neck by grinding, as to make with it an air-tight juncture. 329. Below this juncture, the vessel, V, converges, until it assumes the form of a tube, reaching nearly to the bottom of the reservoir. Around the tube thus formed, a coil of zinc is supported, so as to be above the orifice of the tube, constituted as abovementioned. 330. If the reservoir be sufficiently supplied with diluted sulphuric acid, the reaction between this solvent and the zinc will evolve hydrogen gas. The gas thus evolved, if not allowed to es- cape, will force the liquid which ge- nerates it through the orifice of the tube proceeding from the vessel, V, into the cavity of this vessel, until the quantity of the acid remaining below, is insufficient to reach the zinc. When- ever this takes place, the evolution of hydrogen ceases. As soon, however, as, by opening the cock, any portion of the gas is allowed to escape, an equi- valent bulk of acid descends into the reservoir, and reacts with the zinc, until, by the further generation of hydrogen, the portion of acid which may have descended shall again be expelled from the lower into the upper vessel. At the same moment that, by turning the cock, C, a. jet of gas is emitted, the plate of the electrophorus being lifted against the knob, n, of the wire, an electrical spark will pass from the other end of this wire to that of the wire supported by the cock, and of course uninsulated by its communication with the operator's hand. Consequently the jet of hydrogen will be ignited, and will light a candle exposed to its influence. 331. For a rationale of the electrophorus, as also for other exemplifications of the igniting power of electric discharges, I refer to my treatise on statical or mechanical electricity. Ignition by Galvanism. Galvanic Apparatus for Lighting a Lamp. 332. The following figure represents an instrument for lighting a lamp by means of a galvanic discharge from a calorimotor ; for a more ample explanation of which I must refer the reader to my lectures on galvanism. 333. The plunger, P, being depressed by means of the handle attached to it, some acid contained in the box, B, is displaced, so as to rise among the galvanic plates. By the consequent evolution of the galvanic fluid, a platinum wire, fastened between the brass rods forming the poles of the calorimotor, and projecting over the lamp as seen at R, is rendered white hot, and a filament of the wick, previously laid upon it, is inflamed. CALORIC. 59 334. The weight acts as a counterpoise to the plunger, and when it is not depress- ed by the hand, keeps it out of the acid. Galvano-ignition Apparatus. 335. In many of my experiments, for the purpose of producing the temperature of combustion in cavities inaccessible by ordinary means, 1 employ a wire ig- nited by being made a part of a galvanic circuit. 336. Of the apparatus by which this object is effect- ed, 1 shall here give a description accompanied by a figure, which will convey a general idea of the con- trivance, applicable to all cases where it may be used. Having thus prepared the student, I shall in future re- fer to it under the name at the head of this article, in order to avoid circumlocution, and unnecessary recur- rence to analogous description. D represents a section of a metallic disk. A B, two metallic rods, which should be of iron, if in contact with mercury, but which otherwise may be of brass, are made to enter the cavity. If, as in general, the rods pass through a metallic plate or cylinder, one of them may be solder- ed to the plate or cylinder. The other must be so se- cured, where it passes through the metal, by a. collar of leather, , as to insulate it from all metallic con- tact, and to render the aperture through which it en- ters, air-tight if necessary. The rods may extend into the cavity to any convenient distance, their terminations being approximated, more or less, as may be desirable, but not brought in contact. To one of these rods, where it terminates within the cavity, one end of a fine platinum wire is soldered ; the other end of the wire being soldered in like manner to the similarly situated ter- mination of the other rod. To the rod secured by the collar of leather, at the termi- nation on the outside of the cavity, a gallows screw is attached, by means of which a flexible lead or copper rod may be made fast at one end, while the other is fastened to one of the poles of a competent calorimotor. To the other pole of the calorimo- tor, another rod is attached at one end, which at the other may be secured by a gal- lows screw, either soldered to the plate, or to the projecting extremity of the unin- sulated rod, as in the figure. Sometimes the last mentioned rod is left at liberty, so as to be made to touch, when desirable, any part of the apparatus having a metallic communication with the uninsulated rod. If, under these circumstances, the calo- rimotor be put in operation, the wire will be ignited. 60 IMPONDERABLE SUBSTANCES. Ignition by Collision. 337. The ignition of spunk, tinder, or gunpowder, by means of flint and steel, comes under this head. In the rotary match box, the collision is produced by a wheel thrown into rapid rotation. An analogous apparatus, called a steel mill, had long been employed to procure light in mines infested with light carburetted hydrogen, prior to Sir H. Davy's invention of the safety lamp. This gas explodes on coming into contact with the flame of a lamp or candle, but is not ignited by the scintillations from a steel mill. Heat produced by Percussion. 338. A rod of iron hammered with great rapidity by a skilful workman, will become so hot as to ignite a sulphur match, and phosphorus may be easily ignited in this way ; but the same piece of iron cannot be ignited by percussion more than once. 339. Coins grow hot when struck in the coining press, but, if cooled during each interval between the blows, are less heated at each successive blow. At the same time the density of the mass is permanently increased, probably by the expulsion of the caloric, interposed between the metallic atoms. (272.) Heat produced by Friction. 340. Friction, as a means of producing heat, differs from percussion ; since in the case of friction, the effect being confined to the surfaces of bo- dies, there is no condensation of the mass subjected to the process. Colli- sion differs both from percussion and friction ; for it produces ignition only in the minute portions of matter which are struck off. The masses em- ployed are not heated. 341. It is well known that savages avail themselves of the friction of wood to produce fire. Wood revolving in the lathe may be carbonized, throughout the circle of contact, by holding against it another piece pro- perly sharpened. By rubbing one cork against another, sufficient heat is produced to ignite phosphorus. Glass so heated by the Friction of a Cord, as to separate into two parts on being sub- jected to Cold Water. 342. The process for dividing a tube, which I am about to describe, illustrates at once the heat produced by friction, and the non-conducting power of glass. 343. Some years ago, Mr. Isaiah Lukens showed me that a small phial or tube might be separated into two parts, if subjected to cold water, after having been heated by the friction of a cord made to circulate about it, by two persons alternately pull- ing in opposite directions. I was subsequently enabled to employ this process for dividing large vessels of four or five inches in diameter; and likewise to render it in every case more easy and certain, by means of a piece of plank forked like a boot- jack, as represented in the following figure, and also having a kerf or slit cut by a saw, parallel to, and nearly equidistant from, the principal surfaces of the plank, and at right angles to the incisions forming the fork. 344. By means of the fork, the glass is easily held steady by the hand of one ope- rator. By means of the kerf, the string, while circulating about the glass, is confined to the part where the separation is desired. As soon as the cord smokes, the glass is plunged into water, or if too large to be easily immersed, the water must be thrown upon it. This method is always preferable when the glass vessel is so open, that, on being immersed, the water can reach the inner surface. As plunging is the most effectual method of employing the water, 1 usually, in the case of a" tube, close the end which is to be sunk in the water, so as to restrict the refrigeration to the outside. CALORIC. 61 345. Rationale. If the friction be continued long enough, the glass, though a very bad conductor of heat, becomes heated throughout in the part about which the fric- tion takes place; of course it is there expanded. While in this state, being suddenly refrigerated by the cold water on the outside only, the stratum of particles imme- diately affected, contracts, while that on the inside, not being chilled, undergoes no concomitant change. Hence a separation usually follows : see (264, &c.) Ignition by Attrition. 346. If, whilst a thin disk of sheet iron is made to revolve rapidly upon its axis by means of a lathe, the circumference be brought into contact with a plate of steel, heat will be so copiously evolved at the place of collision, that the steel may be actually divided by the successive ignition and abra- sion of a portion of its particles. The ignition is confined to the steel, be- cause the heat, evolved in this case, is too much divided upon the whole circumference of the iron, to affect any part materially; whereas, a few particles of steel having to encounter successively many of iron, the heat, generated by the attrition, accumulates in the former, so as to produce visi- ble ignition. 347. This case differs from that of pure collision, since, although heat is produced in the abraded particles, it is also produced in the mass ; and it differs from that of friction, since, although both of the masses are heated, the greatest heat is evolved in the matter which is abraded. Heat produced by Combination. 348. The union of tin or lead with platinum is productive of a remark- able elevation of temperature. For the exhibition of this phenomenon, both metals must be in the state of foil, and the more fusible metal rolled up in the platinum, so as to form a scroll as large as can be conveniently ignited by means of the blowpipe. As soon as the scroll reaches a reel heat, it be- comes instantaneously incandescent, the union being effected with an as- tonishing energy. IMPONDERABLE SUBSTANCES. Experimental Illustration. 349. Tin foil and platinum foil are rolled up into a scroll, the tin being innermost, and the whole subjected to the flame of the hydro-oxygen blowpipe, supplied by currents of hydrogen gas and atmospheric air. Almost as soon as the mass reddens, it becomes incandescent with an energy almost explosive. (250, &c.) Boiling Heat produced in Alcohol, by the Mixture of Sulphuric Acid with Water. 350. The evolution of caloric, produced by the mixture of liquids, has long been an object of attention among chemists. A sensible in- crease of temperature arises from the mixture and consequent combination of alcohol with water. When sulphuric acid is added to water, an analogous result ensues, but the rise of tem- perature is much greater. The heat, thus gene- rated, may be conveniently exhibited by means of the apparatus represented by the adjoining figure, and the process which I am about to de- scribe. 351. Into the inner tube introduce as much alcohol, coloured to render it more discernible, as will occupy it to the height of three or four inches. Next pour water into the outer tube, till it reaches about one-third as high as the li- quid contained in the inner tube ; and afterwards add to the water about three times its bulk of concentrated sulphuric acid. The liquid in the inner tube will soon boil violently, so as to rise in a foam. Solution the Means of producing Heat or Cold. 352. Solution produces either heat or cold, according to the nature of the substance dissolved and of the solvent employed. 353. In absorbing and dissolving gaseous ammonia or chlorohydric acid gas, the resulting liquid becomes hot. Water becomes cold in dissolving nitre, and still colder in dissolving nitrate of ammonia. Sulphuric acid be- comes at first boiling hot, and afterwards freezing cold, by successive addi- tions of snow. Evolution of Caloric by Mechanical Action inducing Chemical Decom- position. 354. With the view of showing the necessity of distinguishing heat as a latent cause from sensible heat, the explosion of a fulminating powder by percussion was exhibited. This phenomenon falls under the definition given at the head of this article. Ignition produced in this way has of late been advantageously applied to fire-arms and fowling pieces. (30.) CALORIC. 63 355. It seems probable that the mechanical force of the blow causes some particles of the compound to be nearer to each other; in consequence of which an arrangement of the elements ensues, inconsistent with the re- tention of the large quantity of caloric with which they were previously combined. 356. The inflammation of a friction match, appears to me to arise in part from heat generated by friction, and in part from mechanical impulse, in- ducing a chemical reaction between the ingredients, and exposing them to the air. Matches, which take fire when crushed, owe this result to the last mentioned cause only. 357. The rationale of the chemical reaction of the ingredients, will be given under the heads of sulphur, phosphorus, and the chlorates. Heat produced by Condensation experimentally illustrated. 358. Spunk or tinder may be ignited, if introduced into a condenser of appropriate construction, and the air forcibly condensed upon it. 359. It has already been shown that, during its rarefaction, air becomes cooler, while during its condensation it becomes warmer. It seems that when the compression is carried very far, so much caloric is liberated as to cause ignition. This result is attained by means of a small condenser, the construction of which does not differ from that which has been described (145, &c.), excepting that a cock for the introduction of the spunk is sub- stituted for the valves. The ignition is accomplished by having the piston so situated, as that there may be as much air as possible included by it, and then driving it home, with a jerk, so as to condense the air upon the matter to be ignited with great force and rapidity. Sometimes the instru- ment is made of glass without a cock, so that the ignition may be seen; the spunk being inserted into a cavity in the end of the piston, which must of course be withdrawn as soon as the ignition is effected, in order to make any useful application of the ignited spunk. 360. It appears evidently from this phenomenon that, in air, the quantity of caloric in proportion to the ponderable matter lessens as the density in- creases. Or, in other words, as the space allotted to the air is diminished. 361. This inference would appear, at first view, irreconcilable with those experiments which demonstrate that, in steam, the quantity of caloric is always directly as the weight of water; but the discordancy disappears when we consider that the heat of the condensed air is estimated after the escape of the sensible heat liberated by the compression; while in the case of steam this cannot be permitted, as a loss of sensible heat would be at- tended with a partial condensation, producing a proportionate diminution of density. 362. If steam, formed at the boiling point of 212, and having no access to water in the liquid form, were to be raised to some higher temperature, 500 for instance, it might be subjected to compression without being par- tially liquefied ; so that the same law would apply to it as to atmospheric air, which always exists at a heat far above its boiling point, arid has no access to any of its own kind of ponderable matter in the liquid form. 363. By the boiling point of air, I mean that temperature below which it would become liquid. We have, I think, reason to infer that all aeriform fluids would prove susceptible of liquefaction, if our ability to condense them, or our power of producing cold were unlimited. 64 IMPONDERABLE SUBSTANCES. 364. It has been suggested (257, &c.), that the caloric thus condensed may belong to the space, and not to the air. Experimental Illustration. 365. Spunk ignited in consequence of the compression of air, by means of an appropriate condenser. Of Fermentation as a Source of Heat. 366. It is well known that vegetable substances, while undergoing fer- mentation, acquire a great accession of heat ; and that green hay is at times spontaneously ignited. The heat generated in stable litter is employed to sustain the temperature necessary to the corrosion of the metal in the manufacture of white lead. Of Vitality as a Source of Heat. 367. The temperature of warm blooded animals demonstrates the power of animal life to evolve caloric. In no other respect is chemical reaction so analogous to that which takes place within the domain of vitality, as in their common association with heat, both as cause and effect. The old chemical law that bodies do not act unless fluid, to which the actual excep- tions are but few, shows how much the processes of chemistry are depen- dent on the principle, without which there could be no fluidity. The de- pendency of life on temperature is self-evident. Seeds and eggs lie dor- mant until excited by a due degree of heat. Of the Means of exciting or supporting Heat for the Purposes of Chemistry. 368. It is well known that the activity of fire is dependent on the supply of air, as well as on the quantity and quality of the fuel. 369. As the air which comes into contact with a fire is necessarily much rarefied by the expansive power of heat, it has consequently a tendency to ascend in a vertical current, giving place to the colder and heavier air in the vicinity, agreeably to the principles already illustrated. See (282) and (286). The limits of this vertical current of heated air, in the case of a smoky lamp flame, are well indicated by the fuliginous particles. It may, however, be observed that the influx of the cold air takes place not only on a level with the flame, where it must quicken the combustion, but also above the flame, where it narrows the heated column and retards its progress. In the Argand lamp, a glass chimney defends the vertical current from lateral pressure, until it has attained a sufficient height to cause an adequate current of air to act upon the flame. 370. In conformity with the principle thus illustrated by this elegant and useful contrivance, all air furnaces are constructed. The hot air and va-. pour proceeding from the fire, being received into a flue, or the furnace being tall enough of itself to protect the ascending current, all the air which flows in to take its place is made to pass through the fuel. 371. It would not be expedient to take up the time of the student with a detailed explanation of the various furnaces used by chemists. Some of them will be introduced in subsequent illustrations, as associated with CALORIC. 65 processes, in which their utility and the method of using them will be evident. Experimental Illustration. 372. An Argand lamp shown and explained. Also an Argand lamp with concentric wicks. Of the Bellows, and of Forge Fires. ' 373. The bellows is so universally known as the means of exciting com- bustion employed by smiths, as to render it scarcely necessary to mention the forge fire as among the most efficient and convenient methods of pro- ducing heat for the purposes of chemistry. The supply of air is, in this case, yielded by an operation analogous to that of the condenser. (148, &c.) 374. In the double bellows, the additional compartment performs a part, in equalizing the efflux, equivalent to that of the air vessel in the case of the forcing pump, the valves operating in the same way. (143.) Lamp without Flame. 375. About the wick of a spirit lamp, a fine wire of platinum is coiled, so as to leave a spiral interstice be- tween the spiral formed by the wire ; a few turns of which should rise above the wick. If after lighting a lamp thus constructed, the flame be extinguished by a gentle blast, or the transient application of an extinguisher, the wire will be found to remain red hot ; as it retains sufficient heat to support the combustion of the alcoholic vapour, although the temperature is inadequate to produce inflam- mation. 376. Rationale. The metallic coil appears to serve as a reservoir for the caloric, and gives to the combustion a stability, of which it would other- wise be deficient. There is some analogy between the operation of the wire in acting as a reservoir of heat in this chemical process, and that of a fly wheel as a reservoir of momentum in equalizing the motion of machinery. Of the Mouth Blowpipe. 377. As a fire is quickened by a blast from a bellows, so a flame may be excited by a stream of air propelled through it from the blowpipe. The instrument known by this name, is here represented in one of its best forms. It is susceptible of various other constructions ; all that is essential being a pipe of a size at one end suitable to be received into the mouth, and to- wards the other end having a bend nearly rectangular, beyond which the bore converges to a perforation, rather too small for the admission of a 9 66 IMPONDERABLE SUBSTANCES. common pin. There is usually, however, an enlargement, as represented in this figure, to collect the condensed moisture of the breath. 378. The mouth blowpipe is of great service in assaying minute por- tions of matter, so as to form a general idea of their nature. The cele- brated Berzelius, who has written an octavo volume on the subject of this in- strument, informs us that by means of it Gahn discovered tin in a mineral, in which it had not been detected by analysis, although existing only in the proportion of one per cent : also that he had often seen him extract a glo- bule of metallic copper from the ashes of a quarter of a sheet of paper. The utility of the mouth blowpipe will be manifested in several future illus- trations. Of the Enameller 's Lamp. 379. A lamp, so made as to be excited by a jet of air from a stationary blowpipe, supplied by a double bellows, gasometer or gas-holder, is employ- ed much by chemists and artists for bending glass tubes, or heating them so as to blow, on them, bulbs for thermometers. Such lamps having been ori- ginally used by enamellers, are designated accordingly. Of the Hydro-Oxygen or Compound Blowpipe. 380. In the year 1801, by the invention of the hydro-oxygen or compound blow- pipe, of which I published an account the following year, I was enabled to fuse se- veral of the pure earths which had previously been deemed infusible ; and likewise not only to fuse, but to volatilize pure platinum. Subsequently, my friend Professor Sillirnan, by a more extended use of the instrument, fused a great number of sub- stances insusceptible of fusion by the common blowpipe. My memoir was repub- lished in London, in Tilloch's Magazine; also,at Paris, in the Annales de Chimie, and was noticed by Murray in his treatise of chemistry, and by Dr. Hope, in his lectures; yet, when a modification of the hydro-oxygen blowpipe was contrived by Mr. Brooke, Dr. Clarke, by means of this modification, repeated my experiments and those of Professor Silliman, without any other notice of our pretensions than such as were calculated to convey erroneous impressions. Engraving and Description of an improved Compound Blowpipe and its Appendages. 8 G 381. The following figure represents a compound blowpipe which I executed myself in the year 1813; but, fearing it might be deemed contrived and unnecessarily CALORIC. 67 complex, I did not then publish an account of it. Experience has shown that the complication of its structure does not render it more difficult to use than the sim- plest instruments intended for the same purpose ; while its parts are peculiarly sus- ceptible of advantageous adjustment. :>-2. B is a brass ball, with a vertical perforation, terminating in a male screw above, and in a female screw below. Another perforation, at rigfht angles to this, causes a communication with the tube t, which enters the ball at right angles. A similar but smaller brass ball may be observed above, with perforations similar to those in the larger ball, and a tube, in like manner, entering it laterally. This ball terminates in a male screw below as well as above. The thread of the lower screw is curved to the left, while that of the screw of the larger ball, which enters the same nut, n, is curved to the right. Hence the same motion causes the male screws to approach, or recede from each other, and thus determines the degree of compres- sion given to a cork which is placed between them in the nut. At S, above the ball, a small screw may be observed, with a milled head. This is connected with a small tube which passes through the cork in the nut, n, and reaches nearly to the external orifice, o, from which the flame is represented as proceeding. This tube is for the most part of brass, but at its lower end terminates in a tube of platinum. It com- municates by lateral apertures with the cavity of the upper ball, but is prevented by the cork from communicating with the cavity in the other ball. Hence it receives any gas which may be delivered into the upper ball from the lateral pipe which en- ters that ball, but receives none of the gas which may enter the lower ball, B. 383. Into the female screw of the latter, a perforated cylinder of brass, r., with a corresponding male screw, is fitted. The perforation in this cylinder forms a conti- nuation of that in the ball, but narrows below, and ends in a small hollow cylinder of platinum, which forms the external orifice of the blowpipe, o. 384. The screws, s sss, are to keep, in the axis of the larger ball, the tube which passes through it from the cavity of the smaller ball. The intermediate nut, by compressing about the tube the cork which surrounds it, prevents any communica- tion between the cavities in the two balls. By the screw, S, in the vertex, the ori- fice of the central tube may be adjusted to a proper distance from the external ori- fice. Three different cylinders, and as many central tubes with platinum orifices of different calibres, were provided, so that the flame might be varied in size, agreeably to the object in view. 385. I have always deemed it best to transmit the oxygen gas through the tube in the axis, since two volumes of the hydrogen being required for one volume of oxy- gen, the larger tube ought to be used for the former; and the jet of hydrogen is placed between a jet of oxygen within it, and the atmospheric air without. 386. Under the table is a gallows, G, with a screw for attaching a pipe, leading from a self-regulating reservoir of hydrogen. 387. In order to put this apparatus into operation, it is affixed to a table, as repre- sented in the figure, or to a smaller stand, and secured to the side of the hydro- pneumatic cistern, so as to be conveniently situated for receiving the oxygen from a gas-holder, through the pipe, P, and the hydrogen through a pipe attached at G. 388. Another pipe, proceeding from a reservoir of hydrogen gas, is attached, by means of the screw and gallows, G, to one of the tubes communicating with the blowpipe. 389. The cavity of the hydrostatic blowpipe may be supplied, either with oxygen, or atmospheric air. In either case, in order to have the instrument in full operation, it is only necessary to open the cocks duly, and inflame the hvdrogen. 390. The heat produced, in this way, by the combustion of hydrogen with atmos- pheric air, is sufficient to fuse platinum; and when oxygen gas is employed, that metal, or any other, may be volatilized. The facility with which the hydro-oxygen flame, whether excited by pure oxygen or common air merely, may be made to act, in any convenient direction, renders it peculiarly serviceable in many operations; its superior cleanliness is a great recommendation. Of Drummond's Lime Light, and of DanielVs and Maugham's Blowpipe, so called crroncovshj. 391. Much has been said in some of the British newspapers, of the application in light-houses, of the light reflected by lime, when subjected to the flame of the com- pound blowpipe. This is treated as a new invention, although in my original Me- moir, published in the year 1802, I spoke of the light so created as intolerable to the naked eye. A similar observation will be found in the description given by my friend, Professor Silliman, of the phenomenon in question. It follows that the English operator can only lay claim to a new application of a previous discovery. 68 IMPONDERABLE SUBSTANCES. 392. In my original memoir on the hydro-oxygen blowpipe, I described and repre- sented by engravings two methods of causing the currents of the two gases employed, to meet. Agreeably to one of these, two perforations were made to unite and form one, at about the tenth of an inch from the external orifice, so as that a section of the ag- gregate would resemble in shape the letters XY. Agreeably to the other method, a smaller tube was made to enter and to be concentric with a larger one, the latter being a little longer, so as that at a little distance from its end, the orifice of the former terminated. The oxygen being supplied through the inner tube, and the hy- drogen through the outer one, the admixture of the oxygen with the hydrogen, took place within the bore of the external tube, at a small distance from its orifice. 393. Not being enabled to procure any platina at the time, I could not construct a blowpipe, of the last mentioned kind, sufficiently refractory ; but about the year 1815, 1 constructed the compound blowpipe above described, and exhibited it to Pro- fessor Silliman, who mentioned this fact in a letter written within a year afterwards. From the time that I was elected Professor of Chemistry in 1818, I have employed this form of the instrument, of which an engraving and description was given in the Franklin Journal (Vol. I, 1826, p. 195,) of a simpler instrument upon the same prin- ciple, an engraving and description of which will be found in Silliman's Journal for 1822. Yet both Professor Daniell and Mr. Maugham, resorted to analogous con- trivances. The former has been called Daniell's hydro-oxygen blowpipe, the other also is distinguished by the name of its contriver. It differs from mine essentially, only in being recurved into an acute angle, so as to throw the flame on a cylinder of lime, for the purpose of illumination. In order to accomplish the same object, 1 had only to direct mine obliquely upwards, instead of resorting to a direction deviating a little from the perpendicular, as is usually preferable. It is surprising that under these circumstances, Maugham should have received a premium for the instrument which he had thus modified, without any reference to the original inventor. Improved Process for the Fusion of Platinum. 394. Latterly by multiplying the jets, and using great pressure, I have been ena- bled to fuse more than two pounds troy, of platinum, into a malleable mass. The method which I employed, was the same essentially as that described in Silliman's Journal, as abovementioned. The gases are made to mingle in a common cavity, and afterwards to supply jet tubes of about the usual size of those employed for blowpipes; these are to be made more or less numerous, in proportion to the quantity of metal to be fused. The great desideratum is to have the pressure on the gases, sufficiently great, and at the same time perfectly steady. MEANS OF PRODUCING COLD, OR RENDERING CALORIC LATENT. Cold by Vaporization. 395. The cold produced by evaporation has been illus- trated by an experiment in which a jet of ether, co-operat- ing with a blast, was productive of the congelation of wa- ter. Pure prussic acid will enable me hereafter to exhibit a phenomenon still more surprising; I mean that of the freezing of one portion of a liquid, by the vaporization of another portion. I shall now proceed to show that the freezing of water may be caused by the ebullition of ether. Water Frozen by Boiling Ether. 396. Let a portion of water, just adequate to cover the bottom, be in- troduced into the vessel represented in the following engraving, as sus- pended within a receiver. Over the water let ether be added, in quan- tity sufficient to form a stratum from an eighth to a quarter of an inch in depth. If, under these circumstances, the receiver be placed on the air- pump plate, and sufficiently exhausted, the water freezes, while the ether boils. CALORIC. 69 397. Rationale. The freezing of the water in contact with the boiling ether, is in consequence of that increased capacity to combine with caloric already explained. (186.) Under these circum- stances, the boiling point of the other is de- pressed below the freezing point of water; and consequently it causes the congelation of that li- quid from the same cause, that melted tin or lead will congeal under boiling water. Engraving and Description of an Apparatus and Process for the rapid Congelation of Water, by the explosive Evolution of Ethereal Vapour consequent to the combined influence of Rare- faction, and the absorbing power of Sulphuric Acid.* 398. The retort A, contains a small portion of water covered by a stratum of hydric sulphuric ether. The vessel B, holds a stratum of sul- phuric acid of about two inches deep, at the deepest part. Into a tubulure in the side of this vessel, the beak of the retort is ground to fit air-tight, and * By the liberality of the American Philosophical Society, I am permitted to intro- duce this article in my Compendium, although communicated to them for a volume of their Transactions now in the press. 70 IMPONDERABLE SUBSTANCES. is made to receive one end of a recurved tube, of which the other end de- scends about half an inch below the surface of the acid. There is a mer- cury bottle, C, of which the mouth is well closed, and which is furnished with two cocks, one of which communicates with the air pump, the other with the vessel, B. The mode of operating is as follows: the bottle is previously exhausted, and kept in a state of exhaustion by closing both of the cocks, the pump being put into operation and the cocks opened simultaneously, the power of the acid to absorb the vapour, co-operating with that of the va- cuum and the pump in exhausting the air and vapour from the retort, causes an explosive vaporization of the ether, and a consequent rapid congelation of the water. Congelation of Water in an exhausted Receiver by the aid of Sulphuric Acid. 399. In the experiment above illustrated, water is frozen by the rapid abstraction of caloric, consequent to the copious vaporization of ether when unrestrained by atmospheric pressure. In vacuo, water undergoes a vapo- rization, analogous to that of the ether in the preceding experiment; but the aqueous vapour evolved in this case is so rare, that it cannot act against the air-pump valves with sufficient force, to allow of its being pumped out of a receiver with the rapidity requisite to produce congelation. However, by the process which I am about to describe, water may be frozen by its own vaporization. 400. A thin dish, or pane of glass, covered by a small quantity of water, and situated over some concentrated sul- phuric acid in a broad vessel, is placed within a receiver, on the air-pump plate, as re- presented in the annexed en- graving. Under these circum- stances, the exhaustion of the receiver causes the congelation of the water. 401. Rationale. So long as there is no diminution of the thin aqueous vapour which, in the absence of the air, occupies the cavity of the receiver, the elastic reaction of that vapour prevents the production of more vapour; but when, as in the case in point, the vapour is largely in contact with sul- phuric acid and consequently rapidly absorbed, a corresponding vaporiza- tion of the water takes place to supply the deficiency thus created. The caloric requisite for the generation of the vapour thus formed, is taken from the residual liquid, which finally freezes in consequence. (229.) Improved Apparatus for freezing Water by the aid of Sulphuric Acid. 402. Finding the experiment, for which the apparatus represented by the preceding figure is usually employed, liable to fail from the imperfection of cocks, dependent for their efficacy on a metallic joint, I contrived the appa- ratus which the opposite engraving is intended to represent, and which I shall proceed to describe. A brass cover is so well fitted to the rim of a Apparatus for the Congelation of Water in Vacuo, by means of Sulphuric Acid. (Page 70.) CALORIC. 71 large glass jar as to be quite air-tight. In operating, the bottom of the jar was covered with sulphuric acid, and another jar with feet, also supplied with acid enough to make a stratum half an inch deep on the bottom, is in- troduced as represented. The bottom of the vessel last mentioned, is, by means of the feet, kept at such a height above the surface of the acid in the outer jar, as not to touch it. Upon the surface of the glass vessel, a small plate of very thin sheet brass is placed, made concave in the middle, so as to hold a small quantity of water. The brass cover is furnished with three valve cocks, one communicating with the air-pump, another with a barome- ter gauge, and the third with a funnel supplied with water. 403. With the apparatus thus arranged, having made a vacuum on a Saturday, I was enabled to freeze water situated on the plate, and to keep up the congelation till the Thursday following. As water in the state of ice evaporates probably as fast as when liquid, the whole quantity frozen would have entirely disappeared during the night, but for the assistance of a watchman whom I engaged to supply water at intervals. At a maximum I suppose the mass of ice was at times about two inches square, and from a quarter to a half an inch thick. The gradual introduction of the water, by aid of the funnel and valve cock, and of the pipe represented in the figure, by which it was conducted to the cavity in the sheet brass, enabled me to accumulate a much larger mass than I could have otherwise pro- cured. The brass band which embraces the inner jar near the brim, with the three straps proceeding from it, serves to keep this jar in a proper posi- tion ; that is, concentric with the outer jar. 404. In this experiment, I employed an air-pump upon a new construc- tion, which I contrived a few years ago, and of which a description will be given in the Appendix. 405. Congelation, as effected in the experiments above described, may be accomplished by the aid of any substance having a very strong affinity for water, as for instance chloride of calcium, clay, or whinstone, after having been rendered anhydrous by ignition. Even parched meal or flour has been successfully employed in the process. Of the Freezing of Mercury by the Vaporization of Ice. 406. If a pear-shaped mass of ice containing the metal be suspended over a large surface of sulphuric acid, and a good exhaustion obtained, it will freeze the quicksilver which may be kept solid for several hours. Wollastori's Cryophorus. 407. The adjoining figure represents the cryophorus, or frost bearer, an instrument invented by the celebrated Wollas- ton, in which congelation is produced in one cavity by rapid condensation in another, consequent to refrigeration. 408. In form, this instrument obviously differs but little from the palm glass, already described. (213, &c.) It is supplied by the same process with a small portion of water instead of alcohol; so that there is nothing included in it but water, either liquid or in vapour. 409. The cryophorus being thus made, if all the water be i allowed to run into the bulb near the bent part of the tube, C J and the other bulb be immersed in a freezing mixture, the ^ water will be frozen in a few minutes. 72 IMPONDERABLE SUBSTANCES. 410. Rationale. There is no difference between the causes of this phe- nomenon and those by which the congelation of water in vacuo is effected by the aid of sulphuric acid; excepting that in the one case the aqueous vapour is absorbed by the acid, in the other condensed by the cold. In either instance it is rapidly removed, and a proportionably rapid vaporiza- tion of the water ensues, abstracting the caloric of fluidity from the residual portion. Large Cryophorus. o 411. This figure represents a very large cryophorus, the blowing of which I superintended, and by means of which I have successfully repeated Wollaston's experiment. 412. This instrument was about four feet long, with bulbs of about five inches in diameter. Modification of the Cryophorus. 413. Two flasks, of which the necks have flanged orifices, are so secured in a wooden frame that, by the pressure of screws, S S, and gum elastic disks, the orifices of a tube are made to form with them severally, air-tight junctures. The orifices of the tube are furnished with brass flanges, which correspond with those terminating the necks of the flasks. 414. Midway between the junctures a female screw is soldered to the tube for the insertion of a valve cock V, by means of which, and a flexible tube extending to an air-pump, the flasks may be exhausted, and then closed. A small quantity of water having been previously introduced into one of them, if, while the exhaustion is sustained, the other flask be refrige- rated by ice and salt, the water will be frozen. 415. This apparatus may be applied to the purpose of desiccation, by placing the article to be dried in one receptacle, and quicklime, chloride of calcium, or concentrated sulphuric acid in the other. The orifice of the receptacles may be made larger without inconvenience. Two large cylin- ders, for instance, may be used. CALORIC. 73 Chemical Combination as a Cause of Cold. 416. Chemical union, although more frequently the cause of increased temperature, is in many cases productive of the opposite effect. 417. There are few instances of chemical union, which are not accom- panied by a change of capacity. Of the cause of such changes, we are utterly ignorant, and of course have no more reason to wonder when, by an absorption of caloric, cold is the consequence of chemical reaction, than when, by an evolution of caloric, heat arises from the same source. 418. In the case of the solution of snow in concentrated sulphuric acid, already adduced, we find these opposite effects resulting apparently from the same cause. Under the same head of solution, as a cause of heat or cold, it was mentioned that nitre and nitrate of ammonia produce cold during their so- lution. This is equally true in the case of many other salts. But the most efficient mean of artificial cold, is the solution of ice, in consequence of the reaction between it and the more deliquescent salts, or the mineral acids. 419. It may be inferred, from the statements already made, that the temperature of freezing water, or melting ice, is 32 ; and that when ice is surrounded by other bodies at a higher temperature, it will continue to ab- stract from them the caloric necessary to its fusion, until it be all liquefied. It must be evident that the minimum temperature which can be thus attain- ed is 32. But by mingling ice in a divided state, with certain salts or acids, having a great affinity for water, and which form with it compounds of which the freezing point is lower than 32, the mass will abstract caloric from adjoining bodies in a mode quite analogous to that in which ice has been stated to operate; while the minimum temperature attainable is as much lower as the freezing point is lower. Thus the freezing point of salt and snow is about zero of Fahrenheit's scale; consequently on mingling salt with snow, the liquefaction of the resulting mass will proceed, at any temperature above zero, to abstract caloric from all adjoining bodies until they are as cold as the mixture. By the addition of crystallized chloride of calcium, or of diluted nitric or sulphuric acid, to snow, a compound may be formed, of which the freezing point is below that at which mercury freezes, or 39. Housekeepers have latterly availed themselves of the influence of salt, to remove ice from the marble steps at the entrance of their dwellings; as in this way it may it may be detached without injury to the marble. Table of Freezing Mixtures. 420. The following tables are taken from Thomson's Outline of the Sciences of Heat and Electricity, page 191. Frigorific Mixtures without Ice. Degree of Mixtures. Tlr-nnometcr sinks, rold pro- Parts. ilucod. Nitrate of ammonia - - - 1 ) ,-, . rnri . Water 1 \ From + 50 to + 4 4b Nitrate of ammonia - - - - 1 i * Carbonate of soda - - - - 1 V From + 50 to 7. 57 Water ... . ; 1;J Phosphate of soda - - - - 9 > n Diluted nitric acid - - - I 4$ From + ^ - ^ C2 Phosphate of soda - - - - 9} Nitrate of ammonia - - - - 6V From -f- 50 to 21. 71 Diluted nitric acid - - - - 4 S Sulphate of soda .... Muriatic acid Sulphate of soda .... Diluted sulphuric acid 10 From + 50 to 0. 50 From + 50 to -f- 3. 47 74 IMPONDERABLE SUBSTANCES. Mixtures. Snow, or pounded ice Muriate of soda Snow, or pounded ice Muriate of soda Nitrate of ammonia Part : '- :]} ": ": :1| Q > Diluted sulphuric acid Snow Muriatic acid - - - 2j - 8) - 5$ 7 ? Diluted nitric acid - 4 . 4 Muriate of lime - Snow Cryst. muriate of lime - 5 - 2 . 3 Cryst. muriate of lime Snow Cryst. muriate of lime - - - 2 - 1 - 3 - 8 Diluted sulphuric acid - 10 Degree of cold pro- duced. 55 59 62 72 82 6G 33 23 Frigorific Mixtures with Ice. Thermometer sinks, Parts. t) \ 7 1 > From any temp, to 5. From any temp, to 25. From + 32 to 23. From + 32 to 27. From -f- 32 to 30. From + 32 to 40. From -f 32 to 50- From to 66. From 40 to 73. From 68 to 91. STATES IN WHICH CALORIC EXISTS IN NATURE. 421. With two of the modes in which caloric exists in nature, the stu- dent of this Compendium has been made acquainted ; and these are the only modes of its existence generally recognised. As it exists in one of them, it is called sensible heat, being susceptible of detection by the senses, or by the thermometer. In the other it is called latent heat, because the quantity pre- sent in that mode of existence, is not open to those means of detection. But even in this latent state, caloric is known to be influenced by temperature; being liable to be removed entirely from vapours, or liquids, by communi- cation with colder substances; so as to render its subsequent presence in these, a proof of its previous existence in the matter from which it may have been abstracted. 422. It seems to me, however, that, in some substances, caloric evidently exists in a state in which it is wholly independent of external changes of temperature. In this predicament I suppose it to reside in the nitrates, chlorates, and fulminates, and generally in all detonating compounds. 423. If, agreeably to the received chemical doctrines, we are to ascribe the explosive power of such compounds to combined caloric, it must be evi- dent that its condensation in them is wonderfully great. Yet no good reason can be assigned for this prodigious condensation. It cannot be ascribed simply to the attraction of ponderable matter ; since the same ponderable matter which confines it at one moment, liberates it in the next without any adequate assignable cause. 424. Thus the presence of platinum sponge, a cold metallic congeries, causes the caloric of a gaseous mixture of hydrogen and oxygen to escape explosively. An electric spark, or the contact of any ignited matter, pro- duces the same result. The case of gunpowder, exploded by the ignition of the most minute portion of the mass, is equally unaccountable, and like- wise the explosive recomposition of water by a discharge from the same galvanic wires, by which its decomposition may have been effected. 425. The almost irresistible extrication of oxygen in the gaseous state LIGHT. 75 from oxygenated water, by contact with the oxide of silver, is still more in point and even more surprising. 426. I conceive, therefore, that in detonating compounds, caloric is held in a peculiar state, dependent on some hidden cause, of which the de- tection would probably unfold many mysteries in galvanism and electro- magnetism, as well as in chemistry. I deem it more than probable that the cause of electricity is the principal agent in these mysterious phenomena. ** SECTION II. , LIGHT. 427. It must necessarily belong to chemistry to treat of light, so far as it is productive of heat, deoxydizement, and other chemical effects, and so far as it is evolved by chemi- cal processes. 428. According to Newton, light is a subtile fluid, which is either radiated or reflected from every visible point in the universe, in consequence of its elasticity or the self- repellant power of its particles. 429. It comes from the sun, about ninety-five millions of miles, in eight minutes, or nearly at the rate of two hundred thousand miles in a second. 430. Light appears to have no sensible weight. The products of the combustion of phosphorus, carbon, and other combustibles, appear fully equal in weight to the ponderable matter employed. It follows that the loss of the light and heat occasions no diminution of weight; yet enough is emitted by the flame of a candle or lamp to be perceived by many hundred millions of eyes. There is not a luminous point in the universe, from which a sphere of rays is not emitted, in radius equal to any distance from which that point may be seen. 431. According to Huygens, Euler, Young, Fresud, and others, light is due to the undulations of a rare elastic medium, or ether, which pervades the universe. This opinion has, within the last forty years, gained the ap- probation of a majority of men of science. The doctrine of Newton is, however, less difficult to comprehend, and serves sufficiently to associate the phenomena intelligibly. Besides, so long as we assume the existence of a ma- terial cause of calorific repulsion, (11, &c.) we cannot consistently explain the quick communication of heat (289, &c.) without supposing that the parti- cles of caloric radiate from hot bodies, as do those of light from luminous bodies, agreeably to the Newtonian doctrine. But if calorific radiation be ascribed to the emission of material particles by hot bodies, it would be in- 76 IMPONDERABLE SUBSTANCES. consistent not to ascribe the analogous phenomena of light to a like cause. In obedience to these considerations I shall resort to this theory in treating of light as a chemical agent, not without a hope that the objections which have been made to it, may hereafter find an answer in some new view of the subject. Of the Sources of Light. 432. As a source of light, the sun is obviously even more prolific than as a source of heat; and it must be evident, that all the processes which produce ignition must also produce light. 433. There are some cases in which light is emitted without heat. As it comes to us from the moon, as emit- ted by luminous insects, decayed wood, or the phosphores- cent wave, it appears to be unaccompanied by caloric. 434. In the fire-fly, and in many other insects, it is evolved by vital action. Refraction of Light. M 435. When a ray of light passes obliquely from a rarer into a denser medium, it is bent towards the perpendicular direction. When the course of the oblique ray is from the denser medium into one which is rarer, it is bent from the perpendicular direction. 436. Suppose F G X Z to be a body of water. If a pencil of the solar rays fall upon the surface of the water perpendicularly at C, it will penetrate the water with- out deviating from its previous course ; for whatever may be the attraction between the light and the water, it cannot cause any deflection, since it must act equally on either side of each ray. But should a pencil of rays passing through the tube, B, and penetrating the water at C, reach the bottom, it would shine on the pebble, D; whereas, it would shine upon Z, were the water removed. The light in this case passing from a rarer into a denser medium, and entering the latter obliquely, the rays are attracted by the denser medium most on the side nearest to it, and consequently are bent, or refracted, from their previous course. LIGHT. 77 437. About C, as a centre, describe the circle, F H E, and from A draw a diameter, ACE, perpendicular to the surface of the water. Let the lines B C, C I, repre- sent the path of the light in passing from the tube to the bottom of the water. Where these lines intersect the circle, draw K H, I L, parallel to the surface of the water. The angle A C H, which the incident ray makes with the perpendicular, is called the angle of incidence, and K H the sine of this angle. I C E is called the angle of refraction, and I L its sine. In the case of water, the sine I L is al- ways found to be the sine K H, as 3 to 4; but were a mass of glass substituted for the water, the sine of the angle of refraction to that of incidence would be as 2 to 3, and if the glass were replaced by a similar mass of diamond, the ratio would be nearly as 2 to 5 : the ratio being always invariable in the same medium, whatever the angle of incidence may be ; for if the pencil of rays were to proceed to C, from a tube at M, making the angle of incidence, ACM, and the angle of refraction, Y C E, the sine, Y Q, would be the sine, R O, in the same ratio as I L to K H ; and this would hold good as before stated, whether F G X Z were water, diamond, crys- tal, or any other homogeneous and transparent refracting medium. The refraction, which has been thus described as taking place daring the passage of rays from air into other denser media, equally ensues when light passes out of such media into the air. Nor is it in air alone that it takes place ; it is enough that the substances through which it passes be of different densities, or chemically different in their natures. Combustible liquids or solids have been found to refract most powerfully. It was his discovery of this association between combustibility and refracting power, that led Sir Isaac Newton truly to infer the combustible nature of the diamond, from its su- perior efficacy in causing refraction. 438. As an illustration of the case of light refracted, in passing out of denser matter into rarer, let us imagine the eye of an observer placed at the upper orifice of the tube, B, in the figure. Instead of the pebble, Z, which he would see if the water were removed, the pebble, B, will be seen by him. Hence the well known power of water in rendering an object visible, when, in the absence of the liquid, our view would be intercepted by the side of the containing vessel; and hence likewise the broken image which a stick or cord presents to us, when seen partially under water. Difference between the Refracting Influence of a Triangular Prism, and of a Plate or Pane of Glass. 439. In passing through a plate of glass whose surfaces are parallel, the refraction which light sustains from one surface, is compensated by an opposite refraction by the other surface ; but during its passage through a prism as represented in the fol- lowing diagram, it is subjected to a concurrent refraction from two surfaces. 440. Supposing that the re- fracting medium, F G X Z, in the last figure, were bounded by air below as well as above, and its upper and lower sur- faces were parallel, as in the cas e of a plate or pane of glass, a ray of light in passing ob- liquely through it, would be equally attracted, on one side, as it enters, on the other side as it emerges. Hence, after its emer- gence, it will proceed parallel *D on a prism, as represented in the foregoing figure, in the direction of the line, A B; agreeably to the preceding demonstration, it will, on account of the obliquity of its approach, be refracted towards C, and emerging from C, obliquely to another sur- face of the prism, H C K, it will be again most attracted by that portion of the sur- face towards which it inclines. Consequently, it will be refracted so as to proceed in the direction C D. 442. Thus it must be evident that the two surfaces of the prism have a concurrent influence in bending the rays from their previous course; while in the pane, the in- fluence of one surface is compensated by that of the other. 443. The lines, L F and E F, being perpendiculars to the surfaces of the prism, A B L is the angle of incidence, and F B C, the angle of refraction, to the surface at which the rays enter the prism. F C B is the angle of incidence, and E C D, the angle of refraction to the surface from which the rays emerge. 78 IMPONDERABLE SUBSTANCES. Dispersion of Light. 444. Besides, the refraction sustained by a pencil of rays, agreeably to the pre- ceding illustration, they undergo another alteration, the effects of which are very pleasing, and, agreeably to the doctrine of Newton, highly instructive, being the foundation of his theory of colours. 445. Light appears to consist of particles of different kinds; each kind having the property of producing on the retina of the eye a peculiar impression, which being conveyed to the sensoriura creates the idea of a colour. The rays thus capable of acting differently on the retina, seem to be unequally susceptible of refraction. Hence, in passing through the prism, they are separated from each other, forming a beautiful series of all the various colours of the rainbow, in an oblong figure called the spectrum. Under these circumstances, the rays are said to be dispersed, and the process by which they are separated is called dispersion. 446. Let A B represent a part of a window shutter of a room, into which light enters only through the hole C. If the light thus entering be received on a screen, a circular spot on it will be made luminous. But if a glass prism, D O E, be placed before the hole, so that the light may fall advantageously upon the prism, the rays, which had before produced the luminous circle, will be refracted and dispersed, so as to form the spectrum, r g v, consisting of the following colours, arranged in the following order red, orange, yellow, green, blue, indigo, violet. Of the Heating, Illuminating, and Chemical Properties of the Rays. 447. The red rays are found to be pre-eminent in heat- ing power; the violet as remarkable for their superior influence in certain chemical changes, dependent on deoxi- dation. In the middle of the spectrum, the rays have the highest power of illumination. 448. Besides the rays thus mentioned, there are invisi- ble, heat-producing rays beyond the red, and invisible rays producing deoxidation beyond the violet. 449. Agreeably to the observations of Herschel, to whom we are indebted for the discovery of these invisible rays, the greatest heating and deoxidizing power exists just beyond the limits of the visible spectrum; but from LIGHT. 79 ' experiments made by Seebe'ck and Mellone, it appears that the location of the principal heating power is dependent on the nature of the refracting medium. 450. In the spectrum produced by crown or plate glass, the principal heat was in the red, and in that procured by flint glass, beyond the red; a variety of transparent liquid media having been made to occupy the cavities of several hollow glass prisms, it was found that when a prism was- occupied by water or alcohol, the maximum of heat was in the yellow rays; when it was filled with sulphuric acid, or solutions of sal-ammoniac or corrosive sublimate, the max- imum heat was in the orange. 451. Of the rays perceptible by the eye, the red, being the least bent from their previous course, are obviously the least refrangible; and it is no less obvious that the violet, being the most bent, are the most refrangible; also that those rays, which are found equidistant from the red, and violet, have a mean refrangibility. 452. An opinion has been entertained by some philoso- phers that there are only three original and distinct species of light, which seems lately to be sanctioned by one of the most celebrated opticians of modern times. I allude to Sir David Brewster, whose opinions I shall give, by quot- ing them in his own language, from his Treatise upon Optics, page 68, American edition. 453. " With the view of obtaining a complete analysis of the spectrum, I have examined the spectra produced by various bodies, and the changes which they un- dergo by absorption when viewed through various coloured media, and I find that the colour of every part of the spectrum may be changed not only in intensity, but in colour, by the action of particular media; and from these observations, which it would be out of place here to detail, I conclude that the solar spectrum consists of three spectra of equal lengths, viz. a red spectrum, a yellow spectrum, and a blue spectrum. The primary red spectrum has its maximum of intensity about the mid- dle of the red space in the solar spectrum, the primary yellow spectrum has its max- imum in the middle of the yellow space, and the primary blue spectrum has its max- imum between the blue and the indigo space. The two minima of each of the three primary spectra coincide at the two extremities of the solar spectrum. 454. "From this view of the constitution of the solar spectrum we may draw the following conclusions: 455. " 1. Red, yellow, and blue light exist at every point of the solar spectrum. 456. " 2. As a certain portion of red, yellow, and blue constitute white light, the co- lour of every point of the spectrum may be considered as consisting of the predomi- nating colour at any point mixed with white light. In the red space there is more red than is necessary to make white light with the small portions of yellow and blue which exist there ; in the yellow space there is more yellow than is necessary to make white light with the red and blue ; and in the part of the blue space which ap- pears violet there is more red than yellow, and hence the excess of red forms a violet with the blue. 457. " 3. By absorbing the excess of any colour at any point of the spectrum above what is necessary to form white light, we may actually cause white light to appear at that point, and this white light will possess the remarkable property of remaining white after any number of refractions, and of being decomposable only by absorption. 80 IMPONDERABLE SUBSTANCES. Such a white light I have succeeded in developing in different parts of the spectrum. These views harmonize in a remarkable manner with the hypothesis of three colours, which has been adopted by many philosophers, and which others had rejected from its incompatibility with the phenomena of the spectrum." Triangular Glass Prism, conveniently mounted on a universal Joint. This figure represents a triangular glass prism, mounted on a universal joint, supported by a brass stand, so as to be well qualified for the disper- sion of light, agreeably to the experi- ments alluded to in the preceding ar- ticles. A, the glass prism, supported at each end by a pivot. B, B, handles by means of which the pivots are turned, so as to make the prism revolve. C, C, ball and socket, forming a joint, upon which the plate D, D, may be moved so as to assume any serviceable position. Of certain Chemical Effects of Light. 458. I have already adverted to the calorific influence of light, and to its power of producing chemical changes. Among these, the bleaching power of the solar rays is fa- miliar to every body. In this process the rays appear to exercise that modifying influence on the attraction of pon- derable matter already alluded to. (20,21.) Consequently a new arrangement of particles ensues in lieu of that which formed the colouring matter. Certain vegetable leaves, if exposed to the sun in water, have been found to yield oxy- gen gas. Some metallic salts, especially nitrate of silver, are blackened by exposure to light, owing, as is alleged, to deoxydizemerit. v A mixture of hydrogen and chlorine will, in the dark, remain for a long time without combining; but in the rays of the sun will explode. According to Berze- lius, the power of producing this result exists only in the violet rays. 459. Other important processes in which chemical reac- tion is produced by the agency of light, will be mentioned as I proceed. Polarization of Light. 460. This name has been given to a property of light, which causes it often to be divided into two portions, one LIGHT. 81 of which is transmitted, the other reflected, by the same pane of glass: or one portion sustains refraction in an or- dinary degree, the other in an extraordinary degree. Again, all these properties are found to be commutable, so that the portion of the rays which is reflected in one case, may be transmitted in another ; or that which in one case sus- tains the ordinary refraction, in another may undergo the extraordinary refraction, and vice versa. 461. These phenomena are ascribed to the different positions assumed by the different groups of rays, in con- sequence of which certain poles, which the lumeniferous particles are supposed to possess, are variously directed at different times, so as to determine their reflection, or trans- mission, or the degree of their refraction. 462. In consequence of this diversity of position, in the poles of light-producing particles, and the peculiar arrange- ment of the particles of certain transparent bodies, those portions of light, of which the poles are favourably situated for transmission, may pass through such bodies, when other portions, of which the polar positions are different, may be reflected; one group of the rays may undergo the ordinary, the other the extraordinary refraction. Yet after transmission, reflection, or refraction, the polarity of the groups of rays being reversed, those which were transmitted, or unusually refracted, in the first instance, may, in the second, be reflected, or only ordinarily refract- ed; while such as were reflected at first, or ordinarily refracted, may, in the second, pass through, or be unusually refracted. 463. Latterly, it has been ascertained by Professor Forbes of Edinburgh, that the non-luminous rays emitted by heated bodies, are susceptible of affections analogous to those ascribed to the polarization of light. As the phenomena in question are due to the reaction which takes place between masses and particles, agreeably to the defi- nition at the commencement of this work, they belong to natural philosophy proper, not to chemistry. Yet a chemist cannot be indifferent to inquiries which tend to sanction, or correct, his theoretic deductions respecting the important and interesting phenomena of heat. 11 OF PONDERABLE MATTER. 464. Whatever may be the real state of the case, it has been found con- venient by chemists, during the last forty years, to assume the existence of three imponderable principles, in order to account for certain phenomena, and associate them advantageously. The reasoning which tends to justify this course, has been already briefly stated. (10 to 22.) Of two of those principles, caloric and light, I have treated in the preceding pages. Of the other imponderable principle, electricity, whether statical or dynamic, separate treatises will be supplied. 465. In the next place, I shall treat of that "kind of matter which is endowed with weight, and which is in consequence recognised as material by the mass of mankind." (18.) This kind of matter may be generically designated as ponderable. 466. In treating of ponderable matter, it has been deemed expedient to designate substances, which are exclusively or generally the products of animal and vegetable organization, as organic, all other matter being desig- nated as inorganic. Hence, nominally, two branches of chemistry have been created, called organic, or inorganic, accordingly as the objects of at- tention have been such as to justify the one, or the other designation. Yet it is undeniable that no accurate line of demarcation can be drawn between the branches thus distinguished. Substances produced by animal or vege- table life, may in several instances be obtained by the reaction of inorganic bodies; the phenomena in each branch are dependent on the same ultimate elements; and in almost all cases, those of organic chemistry are displayed by means of agents derived from the inorganic world. 467. Nevertheless, the separation of chemical science into the two branches in question, seems to me highly advantageous in practice. Few persons who are not chemists by profession, can acquire more than a general chemi- cal knowledge of important facts, properties, elements, principles, and com- binations, with so much theory as may be necessary to associate them. With those details and minutiae, of which organic chemistry mostly consists, it were useless to endeavour to impart a knowledge during the time allotted to an education, in which the attention of the learner is divided between seve- ral branches of science. But the acquisition of that degree of knowledge which it is reasonable to expect in organic chemistry, is quite easy to a stu- dent who is familiar with the inorganic department of this science; while to one ignorant of the latter, the smallest progress in the former is utterly impracticable. 468. This subject will be recurred to when I enter upon organic chemis- try. Meanwhile, after treating of certain general properties of ponderable matter, or the means of ascertaining or observing them, I shall proceed with the chemistry of inorganic substances. CHEMICAL ATTRACTION. 83 OF CERTAIN GENERAL PROPERTIES OF PONDERABLE MATTER, AND OF THE MEANS OF ASCERTAINING, OR OBSERVING THEM. 469. As introductory to the consideration of the indivi- dual inorganic substances, it will be expedient to treat of Chemical Attraction, Definite Proportions, Specific Gravity, and the Mode of collecting and preserving Gases, formerly designated as Pneumatic Chemistry. These subjects will be considered in the four following sections. SECTION I. OF CHEMICAL ATTRACTION. 470. The word chemical has been used to designate the, attraction which takes place between heterogeneous parti- cles only. I object to this restriction of its meaning, be- cause I consider it as affording a natural line of separation between chemical and mechanical philosophy, to consider the one as treating of the reaction of masses, or of masses and particles, the other of the reaction of particles only. Besides, the process of crystallization, of which I shaU in the next place treat, arises from the reaction of homoge- neous atoms;* and it was among chemists that the investi- gation or observation of the laws and phenomena of crys- tallization originated. I consider the force which causes homogeneous atoms to cohere, whether in the crystalline form or otherwise, as a species of chemical attraction. 471. The attraction which takes place between homoge- neous particles, is designated as attraction of aggregation, attraction of cohesion, or homogeneous attraction. The at- traction which arises between heterogeneous particles, is called chemical affinity, or heterogeneous attraction. Of Attraction of Aggregation or Cohesion, or Homogeneous Attraction. 472. Of this kind is the force which enables bodies to re- sist mechanical division. Overcoming it does not alter the * I use the word particle only to designate those elementary portions of matter which cannot by any natural means be divided. Chemists use the word atom to signify either such a particle, or the smallest portion of a chemical compound, which can exist without decomposition. (472, 507, 550, 551.) 84 PONDERABLE MATTER. chemical nature of a substance. It is the cause of crystal- lization. (See note.) Of Crystallization* 473. Almost all matter, in passing from the fluid to the solid state, assumes regular forms called crystals. As it is inconceivable that homogeneous particles, or atoms, can differ in size or shape, it is not wonderful that when united by the same attractive force, they should produce regular forms. To produce irregular forms, the atoms, or the forces actuating them, should be irregular. In fact, as the deposition of matter from solution, or on the evapora- tion of the solvent, is accelerated or retarded, a corres- ponding change ensues in the crystalline form. In this way various deviations arise from that primary form which is assumed under circumstances which allow the deposition to proceed at the same rate precisely. Those forms, which deviate from the primary form, are called secondary. The various steps by which they are generated from the pri- mary forms, have been most ingeniously traced, or inferred, by Hauy and others. In some instances, the primary or primitive form has been developed by cleavage. 474. It was at one time the general impression, that every chemical compound had an appropriate crystalline form. Latterly it has been shown that certain substances quite different in their nature, as for instance, phosphoric and arsenic acid, assume the same forms in crystallizing. Such substances are said to be isomorphous. In the intro- duction to Thomson's Inorganic Chemistry, several groups of isomorphous substances are mentioned. 475. Other things being equal, crystals are larger in proportion as their growth is slower. They shoot from extraneous bodies, as the sides of the receptacle, or from strings or sticks, in preference to crystallizing in an isola- ted manner. Agitation hastens their production but con- fuses them. The crystalline texture of some of the trap rocks is attributed to slow cooling. The same matter fused, and allowed less time to cool, forms a glass. * The details of crystallography, as they have been presented by Hatly and others, are of themselves so copious as to require for their remembrance a greater effort of the mind than all the chemistry which I expect a candidate for a medical degree to acquire. It is evidently one of those subjects of which a copious knowledge cannot be imparted advantageously during a strictly medical education. The instruction which I shall endeavour to give upon this topic, will be extremely brief. CHEMICAL ATTRACTION. 85 476. Berzelius alleges that, if two flasks, both containing a saturated solution of two parts of nitrate of potash and one of sulphate of soda, be surrounded with ice or cold water, on introducing a crystal of nitrate of potash into one and a crystal of sulphate of soda into the other, crystals will be formed in each flask, of the same nature as that of the crystal introduced. Nitrate of potash will be found crystallized exclusively in the flask first men- tioned, and sulphate of soda as exclusively in the other. 477. Crystals are found in nature and are produced ar- tificially. 478. The precious stones are native crystals. Carbo- nate of lime, common salt, and gypsum, are native pro- ducts, often crystalline in form. Of the Goniometer, or Jingle Measure; an Instrument for measuring the Jingles of Crystals. 479. Crystals may appear to be exactly similar to the eye; but when compared by means of accurate instruments called goniometers, they will often be found to differ in their angles. Of these instruments there are two constructions ; one, being more easy to be used, is of more general utility ; the other, contrived by Wollaston, is complicated, but when skilfully employed is capable of giving more accurate re- sults. 480. The instrument of the easiest application, and which is usually employed, is represented by the following engraving. Of the Common Goniometer. 451. Its construction is founded upon the 15th proposition of Euclid, which de- monstrates that the opposite angles, made by any two lines in crossing each other are equal. Hence it follows that the angles made by the legs, B B, B C B, of this instrument, above and below the pivot on which they revolve, are equal to each other. Consequently, if they be made to close upon any solid crystalline angle, pre- sented to them at C, they will comprise a similar angle on the other side of the' cen- tre about which they turn. This angle is evidently equivalent to that of the crystal 86 PONDERABLE MATTER. and is ascertained by inspecting the semicircle, A, graduated into 180 degrees, pre- cisely in the same manner as a protractor. 482. The construction of goniometers is usually such as to allow the legs to be detached from the arch, in order to facilitate their application to crystalline angles ; and yet, so that they may be reapplied to the semicircle, without deranging them from the angle to which they may have been adjusted. 483. The piece of brass, in which the pivot is fastened, slides in a slit in each leg; so as to permit them to be made of a suitable length, on the side on which the crys- tal is applied. Of Wollastoris Goniometer. 484. The process by which angles are ascertained by means of Wollaston's gonio- meter is as follows: 485. The crystal to be examined is attached to an axis, and so adjusted, by means of suitable mechanism, that the image of a window bar may be seen reflected from one of the crystalline faces, so as to coincide with a line (seen directly) drawn on the wall under the window, parallel to the window bar. By a partial revolution of the axis, and consequently of the crystal, a similar coincidence of the images of the bar and line is produced by means of another face of the crystal, being the next to that first employed-. 486. Meanwhile the number of degrees of a circle moved through, in changing the crystal from the first to the second position, is measured by an index on a gradu- ated arch, and the degrees of the angle, which the surfaces make with each other, thus ascertained. Various Modes of causing Artificial Crystallization. 487. Fusion followed by congelation. Instances: Crystal- lized sulphur, bismuth, antimony, zinc. 488. Solution followed by evaporation in open vessels. Exemplified by salts, acids, alkalies, sugar. 489. Solution with heat followed by refrigeration. Most of the substances which crystallize by evaporation, yield crystals in this way. 490. Solution followed by vaporization at the boiling heat. Crystals may be thus obtained from many salts, but are always minute. 491. Solution followed by saturation. Instances: Potash saturated by carbonic acid or chlorine. 492. Sublimation. This comprises the idea of vaporiza- tion, and condensation into a state of solidity. Instances: Corrosive sublimate, calomel, iodine, arsenic. 493. Solution followed by precipitation; as in the case of the arbor Dianse and arbor Saturni. Crystalline Specimens exhibited. 494. A wooden arch, about fifteen inches high and a foot wide, encrusted with fine blue crystals of the sulphate of copper: also baskets constructed of bonnet- wire, curiously studded with elegant crystals of the same salt. Crystals of the ferroprussiate of potash, more properly called cy- anoferite of potassium, suspended by a cord on which the CHEMICAL ATTRACTION. 87 crystals were deposited during their formation. (475.) These crystals are of an agreeable lemon-yellow colour. 495. A crystalline congeries of alum, about a hundred pounds in weight. Baskets studded with crystals of the same salt. 496. Large cluster of crystallized borax. 497. Crystals of corrosive sublimate and calomel. 498. Crystals of sulphur, arsenic, bismuth, antimony, &c. 499. Various other crystalline bodies. Of Decry stallization. 50Q. It has been ascertained by Dr. Daniell that crystals may be partially developed by solution. When alum is slowly dissolved, its crystalline structure becomes very evident. 501. Specimen of decry stallized alum. Of Water of Crystallization. 502. The well known spiculae, which, by their appearance on the surface of water, indicate incipient freezing, are crystals. In fact, it was from the Greek name for ice, *gi/erTAAfl, that the word crystal was adopted ; as crystals were correctly considered as the products of a process analogous to freezing. This is strictly true in the case of crystals resulting from the congelation of matter from a state of fusion. Water enters into the constitution of many crystals which, when robbed of it by heat or desic- cation, lose the crystalline form. The water thus situated is called water of crystallization. Some substances com- bine with water in different proportions, and consequently assume different forms ; others crystallize with or without water, with a corresponding diversity of form. These re- sults are dependent upon variations of temperature in the solvent at the period of the crystallization. At 86, sul- phate of soda crystallizes without, at 40, with water of crystallization. Chloride of sodium, which is ordinarily anhydrous, is made to unite with water of crystallization at 8 below zero. 503. Crystals usually retain within their crevices a mi- nute portion of the solution in which they have been crys- tallized. Hence the decrepitation of chloride of sodium and other anhydrous salts when heated, from the vapori- 88 PONDERABLE MATTER. zation of the water so retained. The larger the crystals, the more they are liable to this impurity. Of the Consequence of excluding the Air from a saturated Solution of Sulphate of Soda while boiling. 504. If a flask be sealed, so as to be air-tight, while containing a boiling saturated solution of Glauber's salt, (sulphate of soda,) the solution will remain liquid, so long as undisturbed, but on the admission of the air, will often become a compact crystalline mass within a few seconds. In other cases, it will continue liquid for some time, even for 24 hours, and may then crystallize on being poured out of the flask. Sometimes it crystallizes in the neck of the vessel while the operator is pouring it out ; at others, allowing a crystal or other body to fall into the solution, causes crystals to shoot. No satisfactory explanation has been afforded of this phenomenon. It seems as if the re- pulsive and attractive powers were so nearly balanced as to enable a slight external force to determine the prepon- derancy in favour of the latter. That there is an evolu- tion of caloric, consequent to the congelation, is rendered evident by a rise of temperature. Experimental Illustration. 505. Several glass flasks being made about two-thirds full of a saturated solution of Glauber's salt, and sealed up air-tight, the solution remains liquid until the air is admitted. It then crystallizes either spontaneously, or from slight causes. OF CHEMICAL AFFINITY, OR HETEROGENEOUS ATTRACTION. 506. This attraction is never subdued mechanically, un- less when nearly balanced by repulsion; as in the case of compounds which may be exploded by percussion, (29,) or of elastic fluids combined with liquids. (240.) 507. To sever elements, united by chemical affinity, the finest edge producible by human art is utterly incompetent. Thus, chalk consists of lime and carbonic acid ; vermilion, of sulphur and mercury. Yet when reduced to powders perfectly impalpable, the minutest particle, whether of chalk or vermilion, contains the same ingredients as the mass, and in the same proportion. CHEMICAL ATTRACTION. 89 Different Cases of Affinity". 508. First Case Simple Combination. A and B, two heterogeneous substances, unite and form the compound AB. Instances. 509. Copper with zinc forms brass. 510. Copper with tin forms bronze. 511 Antimony w r ith lead forms type metal. 512. Magnesia with sulphuric acid forms Epsom salt, or sulphate of magnesia. 513. Soda with sulphuric acid forms Glauber's salt, or sulphate of soda. 514. With mercury, various metals form amalgams. Experimental Illustration. 515. A portion of gold leaf, being triturated with mer- cury, disappears, forming a chemical compound with the mercury, in consequence of the inherent attraction or af- finity between the heterogeneous particles. 516. Second Case of Affinity. Called single elective at- traction^ or simple affinity. 517. A and B, two heterogeneous particles, being united in the compound AB, another particle, C, being blended with them in solution, unites with one of them, as A, to the exclusion of B. 518. In this case, C is said to decompose AB, and to have a greater affinity for A than for B. Experimental Illustration. 519. Potash being added to a solution of sulphate of magnesia, the magnesia precipitates in white flocks. A like result takes place, on adding a solution of potash to a solution of sulphate of alumina. 520. Rationale. Sulphate of magnesia consists, as its name implies, of sulphuric acid and magnesia. The affini- ty existing between the potash and the acid being greater than between the acid and the magnesia, the latter is dis- placed from combination, and, being by itself insoluble, precipitates. An analogous explanation will apply in the case of the alumina. In each case, the affinity ojf the acid 12 90 PONDERABLE MATTER. for the alkali, predominates over that of the acid for the earth. 521. Third Case of Affinity. Called double elective at- traction, or complex affinity. 522. The compound formed by the particles A and B, being blended in solution with the compound formed by C and D, A combines with D, and B with C. Experimental Illustration. A B AD Sulphate of zinc } 1 Sulphate of lead being mixed with > forms < and Acetate of lead, } f Acetate of zinc. CD C B 523. Fourth Case of Affinity. A and B being in union, C, added in excess, combines with both A and B. 524. When ammonia is added to certain solutions of metallic salts, those of copper or silver for instance, it operates at first as the potash does in the case of single elective attraction abovementioned, and the oxide of cop- per or silver precipitates. But if the ammonia be added in such quantity, as that, after all the acid shall have been saturated, there shall be an excess of alkali, this excess will combine with the precipitated metallic oxide, forming with it a compound which is immediately dissolved. Hence the menstruum which is at first rendered turbid, afterwards becomes clear, and, in the case of the copper, assumes a beautiful and characteristic blue colour. Experimental Illustration. 525. Liquid ammonia being poured into a solution of copper, at first precipitates the metal in greenish flocks ; but, when the alkali is added in excess, these flocks disap- pear, and a blue solution results. Additional Illustrations of Chemical Affinity. 526. In order to show the wonderful power of chemical reagents in producing striking changes, some additional exemplifications of chemical affinity will here be given. This exhibition may excite curiosity in the learner and CHEMICAL ATTRACTION. 91 afford gratification to him, although unprepared to under- stand the intricate play of affinities by which the results are accomplished. Experiments. 527. Silver precipitated by mercury, mercury by copper, and copper by iron. 528. Conversion of two liquids into an adhesive mass by mingling sulphuric acid with a solution of chloride of calcium or nitrate of lime. 529. Solution of ferroprussiate of potash, added to solu- tions of copper and iron. 530. Solution of chromate of potash, added to solutions of lead, mercury, and silver. 531. Ammoniacal nitrate of copper or silver, added to arsenious acid. Of Cohesion as an Opponent to Chemical Combination. 532. There are many substances, among others carbon, which, under certain forms, in consequence of greater hardness, are much less susceptible of chemical reaction, than under others. Thus the diamond, anthracite, char- coal, and tinder, are varities of carbon, which are endowed with a susceptibility of combustion inversely as their hard- ness. Tinder is proverbially ready to take fire, while the diamond is only to be ignited by the aid of extreme heat, and an unusual supply of oxygen. Every body knows how much less susceptible of being acted upon by solvents, are bricks, porcelain, or stone ware, than the earthy mate- rials out of which they are made. In these cases, it would really appear that the attraction between the homogeneous atoms counteracts the heterogeneous affinity which would sever them. Yet I conceive it to be an error to confound the obstruction to chemical reaction thus created, with that which arises from the restriction of the surface in contact with the solvent. Other things being equal, there will evi- dently be more action in proportion as the points of con- tiguity are multiplied, and vice versa. Thus the action of an acid will be less rapid upon a metallic ball, than upon the same weight of metal in the state of foil, fine wire, or turnings; although the attraction of the homogeneous 92 PONDERABLE MATTER. particles is quite as energetic in the one case as in the other. Effects of Mechanical Division experimentally illustrated. 533. If a ball of brass be put into one glass, and only half its weight of brass filings or turnings into another, on adding nitric acid to both, a violent effervescence will ensue in the one, while in the other, the reaction will hardly be discernible. Influence of Solution in promoting Chemical Reaction, expe rimentally illustrated. 534. Tartaric acid and a carbonate, although intimately intermingled in a pulverulent state, do not react until moist- ened, when a lively effervescence ensues. Exception to the Law that Chemical Action requires Fluidity, experimentally illustrated. 535. If slaked lime and muriate of ammonia in powder be mixed, the pungent fumes of ammonia will be perceived. Tables of Affinity. 536. These consist of the names of a series of sub- stances, placed in a column, in the order of their affinity for any one substance of which the name is at the head of the column. The following is an example: Sulphuric Acid. Baryta, Strontia, Potash, Soda, Lime, Magnesia, Ammonia. DEFINITE PROPORTIONS. 93 SECTION II. OF DEFINITE PROPORTIONS. 537. The proportions have been long known to be in- variable, in which substances must be mixed in order to saturate each other, or to produce a compound in which the peculiar characters, or affinities of the ingredients, are extinguished. 538. When substances combine in other proportions than those of saturation, their ratio is no less definite and constant. 539. There is not in any case, except the peculiar one of solution, an indefinite gradation in the proportions in which bodies combine. There are rarely more than four gradations. 540. The number, representing the least proportion in which a substance is known to combine, will, in a great majority of cases, divide the numbers representing the greater proportions without a fraction; and where this result is unattainable, it will still be found that the larger proportion may be divided by the half of the lesser without a remainder. 541. Let A, B, and C be certain substances, and let X, Y, and Z be other substances, severally having an affinity for either A, or B, or C. Let each of the former and each of the latter be combined in the least possible proportion. Consequently, the least combining proportion of each sub- stance will be found three times. It will appear that the proportions of A, B, and C found by combining them with X, will be in the same ratios to each other, as the propor- tions found by combining them with Y, or Z; and reci- procally, that the proportions of X, Y, and Z, will have the same ratios, whether ascertained by their combination with A, B, or C. 542. When, instead of ascertaining the least combining proportions of six substances, the experiment has been ex- tended to any larger number, the same uniformity has been found to prevail in the ratios of the numbers repre- senting those proportions. It has also been found that when numbers are ascertained which express the ratio of the least combining proportions of "a variety of substances to any one substance, as for instance to oxygen, those 94 PONDERABLE MATTER. numbers will express the ratios of the least combining pro- portions of the substances in question, to each other. 543. Numbers representing least combining proportions are called chemical equivalents. As they are merely ex- pressive of ratio, they may be multiplied by any common multiplier, or divided by any common divisor, without affecting their correctness. 544. They are usually so computed as to make the equivalent of oxygen, or of hydrogen = 1. As the equi- valents of these substances are as 1 to 8, it follows, that if hydrogen be represented by unity, oxygen will be 8. If oxygen be unity, hydrogen will be 0.125, or one-eighth of one. Consequently, equivalents, formed upon either basis, may be converted into those corresponding with the other, either by multiplying or dividing by 8. 545. By Berzelius, Wollaston, and Thomson, oxygen has been made the standard. Berzelius assumes it at 100, Wollaston at 10, and Dr. Thomson at 1. The only dif- ference between the equivalents founded upon these num- bers, is in the position of the decimal point. Of Tables of Chemical Equivalents* 546. In these, the equivalents of all known bodies, so far as ascertained, are arranged alphabetically. Such ta- bles are of great utility in practical chemistry. The ope- rative chemist may frequently resort to them with advan- tage. They enable him to store his memory with data adequate to the solution of a great number of questions which must necessarily arise. If he wishes to know how much of any two substances he must take to form a third, he has only to recollect, or to look for, their equivalents in the table, and seek a solution by the rule of three. For as the equivalents of the substances are to each other, so are the quantities of them to be used. Should it be an object to produce only a certain weight of a compound, then, as the equivalent of the compound is to that of either of the ingredients, so is the weight of the compound required, to the requisite weight of either ingredient. 547. In order to know how much of the proper mate- rials he must use to effect a decomposition, he has only to employ them in the ratio of their respective equivalents. * See Appendix for a Table of Equivalents. DEFINITE PROPORTIONS. 95 548. Moreover, when the proportions, afforded by ana- lysis, do not harmonize with well ascertained equivalents, we are warned of the existence of some inaccuracy, which in many cases may be safely corrected so as to make the results accord with them. Wollastorfs Scale of Equivalents. 549. This instrument is so constructed that the computation requisite in using the equivalents is performed by a slide. It has been mentioned that the equivalents may be expressed in any numbers having the same ratios to each other as the least combining proportions of the substances which they represent. The slide enables us to adopt any such numbers as may be con- venient. Equal distances on the slide give the same ratios in different num- bers. If, by moving the slide, we vary one equivalent to 100, for instance, the other equivalents vary proportionally. Of the Atomic Theory. 550. Extension has been proved to be infinitely divisible, and it is not difficult to suppose that the matter, comprised within any given limits, may be susceptible of as many subdivisions as the space in which it is contained. On the other hand, it is obvious, that mechanical division must be limited by the imperfection of the edges or surfaces employed to accomplish it. 551. Were atoms chemically divisible ad infmitum, any one substance, however small in quantity, might be diffused, in a state of chemical combi- nation, throughout any other, having an affinity for it, however great ; for as no one particle in the latter would exercise a stronger affinity than an- other, it would be unreasonable to suppose that each should not have its share. That such a diffusion is impracticable must be evident from the smallness of the number of definite proportions to which substances in combining are restricted, as already mentioned when upon the subject of equivalents. Hence elementary atoms are not considered as liable to an unlimited subdivision, either by chemical or mechanical agency . v (539.) 552. The ratios of the equivalent numbers are supposed to be dependent on, and identical with, those of the weights of the integrant atoms of the substances to which they appertain. Thus the fact that 32 parts by weight of-soda will saturate as much of any acid as 48 parts of potash, is explained by supposing that the weights of the smallest atoms of those alkalies which can exist, are to each other as 32 to 48. 553. In like manner it is explained that, when neutral salts are made re- ciprocally to decompose each other, no excess of either ingredient is in any case observable. The lime in nitrate of lime is to the potash in an equiva- lent weight of the sulphate of potash, as 28 to 48, yet neither is the lime incompetent to take the place of the potash, nor is there too much potash to take the place of the lime. This result is intelligible, if we suppose that, when quantities just adequate for reciprocal decomposition are employed, there is an equal number of atoms of each salt ; the one containing as many atoms of potash weighing 48, as the other contains atoms of lime weighing 28. 554. The "same explanation applies to the fact that, while the sulphuric acid in the sulphate of potash is to the nitric acid in the nitrate of lime as 40 96 PONDERABLE MATTER. to 54, yet there is neither too much of the latter acid nor too little of the for- mer, to produce neutral compounds with the bases to which they are se- verally transferred. 555. On account of the hypothetical association of the numbers, repre- senting the least proportions in which bodies are known to combine, with the supposed relative weight of their atoms, those numbers are as well known by the appellation of atomic weights, as by that of chemical equi- valents. , Of Chemical Symbols. 556. I shall translate from Berzelius an account of the symbols which he has devised, and which it would be well to understand, as they will often be met with. Objections have been made to some part of his plan, but in ge- neral I believe it will be expedient to adhere to it ; since whatever Berze- lius recommends, awakens the attention of chemists universally, and must cause his symbols to be generally understood throughout the chemical world. 557. " We select (says he) as symbols the initial letters of the Latin names of bodies. When the names of several bodies have the same initial, we add to each a letter which it has not in common with the rest ; as, for instance, C signifies carbon, Cl chlorine, Cr chromium, Cu copper, Co co- balt. When, however, the names of a metallic and non-metallic element commence with the same letter, no additional letter is added to the latter. But when two non-metallic elements have a common initial, it is necessary to distinguish one by means of an additional letter. Thus, to distinguish chlorine, bromine, and silicon, severally, from carbon, boron, and sulphur, the symbols of the former are Cl, Br, and Si, while those of the latter are, simply C, B, and S. 558. " The number of atoms is designated by cyphers. A cypher placed to the left multiplies all the symbols to the right, as far as the first cross, -j- or the whole formula. A little cypher, situated to the right of a symbol, and a little above its level, multiplies that symbol only. Thus S 2 O 5 sig- nifies one atom of hyposulphuric acid, consisting of two atoms of sulphur and five of oxygen; while 2S 2 O 5 signifies two atoms of the same acid. In such cases as that just cited, in which two atoms of the radical are united with one, three, or five of oxygen, the expression for the former would be abbreviated advantageously by having a specific sign for a double atom. The sign which I have adopted for this purpose, is a dash across the lower part of the symbolic letter. Thus P signifies a single atom, P* a double atom of phosphorus. Compound atoms of the first order are expressed as in the following example of sulphate of copper Cu O-J-SO 3 . The trisul- phate of the sesquioxide of iron would be expressed by 2Fe O 3 -f-3SO 3 . 559. " It may be expedient to designate the number of atoms of oxygen by dots placed over the letters symbolic of radicals. Thus we may desig- nate the sulphate of copper by Cu S, the trisulphate of the sesquioxide of iron, by 2 Fe S 3 ." * Instead of placing the dash across the lower part of the letter, it is generally placed under it, as the former mode requires type cast for the purpose. DEFINITE PROPORTIONS. 97 List of the Atomic Weights of the Simple Ponderable Substances, together with their Symbols. 560. As the atomic numbers are practically useful, enabling us to know the proportions in which substances are combined, or in which they should be used to produce compounds, it is advantageous to commit them to me- mory as far as possible. The whole number of substances recognised as elementary, agreeably to the present state of our knowledge, is fifty-four. Of these, little more than half are of sufficiently frequent recurrence either in speculation or in practice, to make it desirable to remember their num- bers. I will quote them, therefore, in two distinct tables. Those of which a knowledge is likely to be rarely in demand, I have subjoined in smaller type. The symbols are given in a separate column. In obedience to the example of the British chemists, I employ Po and So, instead of K and Na, as the symbols of potassium and sodium. At. Wts. 6 12 - 202 14 8 16 99 40 40 8 108 24 44 16 64 59 32 - 100 53 52 60 24 95 - 217 69 32 34 561 . It appears from some experiments made by Messrs. Petit and Dulong, that the capacities for heat, or specific heats, of all elementary atoms are the same; so that if the specific heat of any one congeries of atoms be less than that of another having the same weight, it is because the atoms of the one being heavier than those of the other, there are fewer of them in the same weight. Hence the capacities, or spe- cific heats, of equal volumes of elementary substances are greater, as the weights of their atoms are less; so that if, in the case of each, its atomic weight be multi- plied by its specific heat, the product will in general be so nearly the same, that the difference may be ascribed to the inaccuracy unavoidable in experimental investi- gations. 562. Respecting this highly important and interesting inference of Petit and Du- long, Professor A. D. Bache has endeavoured to show in an article published in tha 13 Symbol. Aluminium Al - Antimony Sb - Arsenic As - Barium Ba - Bismuth Bi - Boron B - Bromine Br - Calcium Ca - Carbon C - Chlorine Cl - Copper Cu - Fluorine F Gold Au - Hydrogen H - Iodine I Iron Fe - Lead Pb - Cadmium Cd Cerium Ce Chromium Cr Cobalt Co Columbium Ta Glucinium G Iridium Ir Manganese Mn Molybdenum Nickel Mo Ni At. Wts. Symbol. 14 Lithium L 64 Magnesium Mg 38 Mercury Hg 69 Nitrogen N 71 Oxygen O 11 Phosphorus P 78 Platinum PI 20 Potassium Po 6 Selenium Se 36 Silicon Si 32 Silver Ag 18 Sodium So 200 Strontium Sr 1 Sulphur S 126 Tellurium Te 28 Tin Sn 104 Zinc Zn 56 Osmium Os 46 Palladium Pd 28 Rhodium R 30 Thorium Th 185 Titanium Ti 18 99 Tungsten Uranium W U 28 Vanadium V 48 Yttrium Y 30 Zirconion Zr 98 PONDERABLE MATTER. Journal of the Academy of Natural Sciences, that multiplying the equivalents of twelve principal metals into their specific heat, gives results so widely deviating from uniformity as to take all plausibility from the hypothesis that the atoms of sim- ple bodies have the same specific heat. 5(!3. Dr. Thomson has observed that this law is more likely to be true, since it holds good without doubt in the case of the gases ; and that if it be true we have only to divide the specific heat of hydrogen by the atomic weight of any body, to find its specific heat. Moreover that the specific heats thus found agree very nearly with those ascertained experimentally. 5(54. From the researches of Faraday, it appears that the quantity of the voltaic fluid given out during the solution of various metals, is in the ratio of their atomic weights. It would seem, therefore, as if the imponderable atmospheres, both of caloric and electricity, are held by atoms in the same equivalent proportion. SECTION III, OF SPECIFIC GRAVITY. 565. A clear idea of specific gravity is indispensable to a chemist. Gravity and weight, are synonymous words ; but the term specif c gravity is used to signify the ratio of weight to bulk. Hence the object of all the processes for ascertaining specific gravities, is either to ascertain the weight of a known bulk, or the bulk of a known weight; for whether the substances whose specific gravities are to be found be reduced to the same weight and then measured, or be reduced to the same bulk and then weighed, the ratio of their weights to their bulks will be discovered. If reduced to the same bulk and weighed, their specific gravities will be directly as the weights. If reduced to the same weight and measured, their specific gravities will be inversely as their bulks thus ascertained. 566. Supposing a like bulk of each kind of matter in nature to be weigh- ed, the results, numerically stated, would represent their specific gravities. But since it is not possible to procure an exactly similar bulk of each kind of matter, it is necessary to resort to another mode of reducing their bulks to a common measure. The method adopted in the case of solids and li- quids, is to divide the weight of a given bulk of each body of which the specific gravity is to be found, by the weight of a like bulk of water. This in fact may be stated as the general rule for ascertaining specific gravities. 567. Thus on dividing the weight of any bulk of copper by the weight of a like bulk of water, the quotient is 9. This, therefore, is received as the specific gravity of copper. By a similar procedure, in the case of silver, the quotient is 10.5, in the case of mercury 13,6, in the case of gold, 19.3 : consequently, these numbers are considered as representing the specific gravities of those metals. 568. If the body be lighter than water, as in the case of cork which is only about one-fifth as heavy, the quotient, being less than one, is ex- pressed by a decimal fraction. Thus the specific gravity of cork may be stated to be .2. 569. The gravity of water has been assumed as the standard, because this liquid may always be obtained sufficiently pure ; and it is generally easy to ascertain thes weight of a quantity of it, equal in bulk to any other body. 570. The weight of a quantity of water, equal to the body in bulk, is SPECIFIC GRAVITY. 99 equal to the resistance which the body encounters in sinking in water. Hence, if we can ascertain, in weight, what is necessary to overcome the resistance which a body encounters in sinking in water, and divide by the weight thus ascertained, the weight of the body, we shall have its specific gravity. 571. In the case of a body which will sink of itself, the resistance to its sinking is what it loses of its weight when weighed in water. 572. In the case of a body which will not sink of itself, the resistance to its sinking is equivalent to its own weight, added to the weight which must be used to make it sink. Experimental Demonstration that the Resistance which a Body encoun- ters in sinking in any Liquid, is just equivalent to the Weight of a portion of the Liquid equalling the Body in bulk. 573. This proportion may be experimentally demonstrated, by means of the apparatus represented by the following figure. 574. The cylinder, represented as surrounded by the water of the vase, is made to fit the cavity of the cylinder suspended over it so exactly, that it enters the cylinder with difficulty, on account of the in- cluded air, which can only be made to pass by it slowly. It must, therefore, be evident, that the ca- vity of the hollow cylinder is just equal in bulk to the solid cylinder. 575. Both cylinders (suspended as seen in the figure) being counterpoised accurately upon a scale beam, let a vessel of water be placed in the situation of the vase. It must be evident, that the equiponde- rancy will be destroyed, since the solid cylinder will be buoyed up by the water. If water be now poured into the hollow cylinder, it will be found that, at the same moment when the cavity becomes full, the equi- ponderancy will be restored, and the solid cylinder sunk just below the surface of the water. 576. Hence it appears that the resistance which the solid cylinder encounters in sinking in the water, i overcome by the weight of a quantity of water equal to it in bulk. It must be evident, that the same would be true of any other body, and of any other liquid. 577. Rationale. When a solid body is introduced into an inelastic solid, on withdrawing it a hole is left, which remains vacant of the solid matter ; but no sooner is a body which has been introduced into a liquid withdrawn, than the liquid is found to fill up the space from which it had been removed. 578. It is evident that the force which liquids thus exert to re-enter any space within them from which they are forcibly excluded, is precisely equal to the weight of a quantity of the liquid commensurate with that space ; since, when the space is reoccupied by the liquid, the equilibrium is restored. Consequently, every body, introduced into a liquid, experiences from it a resistance equal to the weight of a quantity of the liquid, commensurate with the cavity which would be produced, supposing the liquid frozen about the solid mass, split open so as to remove it, and the fragments put together again ; and the cavity thus created must obviously be exactly equal to the 100 PONDERABLE MATTER. bulk of the body. It follows, therefore, that the resistance which any body encounters in sinking within a liquid, is equivalent to the weight of a quan- tity of the liquid, equal in bulk to the body. Method of ascertaining the Specific Gravity of a Body heavier than Water. 579. Let the glass stopple, represented in the adjoining figure, be the body. First counterpoise the stopple by means of a scale beam and weights, suspending it by a fine metallic wire. Place under the stopple a vessel of pure water, at the temperature of 60, and lower the beam, so that if the stopple were not resisted by the water, it would be immersed. Add just as much weight as will counteract the resistance which the water opposes to the immersion of the stopple, and render the beam again horizontal. Divide the weight by which the stopple had been previously coun- terpoised, by the weight thus employed to sink it, and the quotient will be the specific gravity. 580. Rationale. The weight requisite to sink the stop- ple measures the resistance to its being sunk in the water ; and this it has been shown is equal to the weight of a bulk of water equal to that of the stopple. Of course, pursuant to the general rule, it is only ne- cessary to see how often this weight is contained in the weight of the stop- ple, to ascertain its specific gravity. Method of ascertaining the Specific Gravity of a Body lighter than Water. 581. Let a small glass funnel be suspended from a scale beam, and counterpoised so as to be just below the surface of some water in a vase, as represented in the diagram. 582. If, while thus situated, a body lighter than water, a small cork for instance, be thrown up under the funnel, the equilibrium will be subverted. Ascertain how much weight will counteract the buoyancy of the cork, add this to its weight, and divide its weight by the sum. The quotient will be the answer. 583. Rationale. The force with which the cork rises against the funnel, is equal to the difference between its weight and the weight of the bulk of water which it dis- places. Of course, ascertaining the force with which it :=== ^^ rises by using just weight enough to counteract it, and adding this weight, so ascertained, to that of the cork, we have the weight of a bulk of water, equal to the bulk of the cork. By this weight, dividing the weight of the cork agreeably to the general rule, the specific gravity of the cork will be found. Method of ascertaining the Specific Gravity of a Liquid. 584. Let the stopple be counterpoised, exactly as as above directed, (579,) excepting that it is unnecessary to take any account of the counterpoising weight. 585. Having, in like manner, ascertained how much weight will sink it k=x SPECIFIC GRAVITY. 101 i in the given liquid, divide this by the weight required to sink it in the water. The quotient will be the specific gravity sought. 586. Rationale. It has been proved that the resistance to the sinking of a body in any liquid, is precisely equal to the weight of a bulk of the liquid, equal to the bulk of the body. Ascertaining the resistance to the immer- sion of the same body in different liquids, is, therefore, the same as ascer- taining the weights of bulks of those liquids, equal to the bulk of the body, and, of course, to each other. And if one of 4he liquids be water, di- viding by the weight of this the weights of the others, gives their specific gravities. 587. If the stopple be so proportioned as to lose just one thousand grains by immersion in water, division is unnecessary ; as the weight of the liquid will be obtained in grains, which are thousandths by the premises. A piece of metal exactly of the same weight as the stopple, may be employed as its counterpoise. 588. In these experiments, the liquid should be as near 60 of Fahren- heit's thermometer as possible. . Hydrometers for Alcohol, for Acid, Saline, and other Solutions, and for Vegetable Infusions. A C miiiiiiiiffliiiiiiiiiiiiiiiiiiiiiiiiiiiiipiiiiiimfflfflnniininniiiiiiiiiiiiniiiiiiiiil 589. In these a constant weight is used to a certain extent, and the differences of gravity are estimated by the quantity of the stem immersed. In those instruments of this construction where several weights are employed, the effect is the same as if the stem of the instrument were lengthened as many times as the number of the^ weights attached to it. r>l0. The preceding engraving represents three hydrometers, A, B, and C, contained in glass vessels. B and C are of glass, and A of metal. 591. B is intended for liquids heavier than water; C, for those which are lighter. In each, the graduation commences at that point of the stem, to which the instru- ment sinks in distilled water. It must of course commence at the top of the stem for liquids heavier than water, and at the bottom of the stem for liquids lighter than water. In the latter case, as in that of spirituous liquors or ethers, the strength being greater as the liquid is lighter, more of the stem is immersed in proportion as the liquid is stronger; but the opposite is true in the case of acid and saline solu- tions, or infusions of vegetable matter; the more the stem emerges from these, the heavier and of course the stronger they are. The instruments are represented as when swimming in pure water. 592. A is an hydrometer of a form much used in this country and in England, both for spirit and infusions of vegetable matter. The stem is virtually lengthened by the use of several small weights, which may be slipped on and off at pleasure. 102 PONDERABLE MATTER, 593. The whole difference between the weight of water and that of the strongest spirit is equal to about two parts in ten. Of course, an hydrometer for spirit should have on its stem a scale of more than two hundred parts, in order to give the specific gravity of any liquid consisting of water and alcohol. To render such graduation sufficiently discernible, the stem would have to be of very inconvenient length. This is obviated by using different weights. When the heaviest weight is upon the stem, the whole of the stem stands above the surface in distilled water. When the liquid contains enough spirit to allow the whole of the stem to sink in it, while' sup- porting this weight, a lighter weight may be used ; and when the stem again would be wholly merged, this last mentioned weight may be exchanged for one still lighter. Supposing the stem graduated into fifty parts, three weights would give fifty degrees each, and the stem unloaded, fifty more. Were the stem graduated into ten parts, nineteen weights would give one hundred and ninety parts, and the stem unloaded, ten more. 594. An instrument, sometimes called a saccharometer, but precisely similar in principle, is used for infusions of vegetable matter, especially for the wort of brewers and distillers, excepting that the scale begins at the top of the stem, with a line which coincides with the surface of pure water, at sixty degrees Fahrenheit, when the hydrometer is immersed in it. When the infusion is strong enough to support the whole of the stem above its surface, a weight is to be added heavy enough to bring the graduated part of the stem into the liquid. And, in like manner, as the infusion is found stronger, weights still heavier must be added; the process being perfectly analogous to, bat the converse of that described in the case of alcohol. Nicholson's Gravimeter ^ for ascertaining the Specific Gravity of Solids, either heavier or lighter than Water. 595. The accompanying cut is a representation of Nicholson's gravimeter, the construction of which is sufficiently obvious. 596. On the upper scale of the instrument, whilst floating in water, place any body, the specific gravity of which is to be found a piece of coin for instance and add as much weight to the same scale as will sink the gravimeter, until a mark, purposely made in the stem, coincides with the surface of the water. The coin is then to be transferred to the lower scale, and as much weight added to the upper one as compensates this change. This weight is obviously just equivalent to the resistance which the coin encounters in sinking in the water. Let this weight be called A. 597. In the next place, the body is to be removed from the gravimeter, and as much weight, B, again added to the upper scale, as will cause the mark upon the stem to coincide with the aqueous surface. Of the weight first employed, no account need be taken; but the weight, A, and the weight B, used in the second and third steps of the process, are to be carefully noted, and added together; the sum of A and B is then to be divided by A, the first number noted. This number, A, re- presents the weight of a bulk of water, equal in bulk to the coin; while the sum of the numbers, A and B is equivalent to the weight of the coin; since that aggregate weight has been found equivalent to the weight of the coin in sinking the gravimeter. Method of finding the Specific Gravity of a Body lighter than Water, by Nicholson's Gravimeter. 598. Should the specific gravity of a light body, as a piece of cork for instance, be in question, place it on the upper scale of the gravimeter, load the instrument, so that the mark on the stem may coincide with the surface of the water, as in the case above stated, a leaden disk being previously laid upon the lower scale. The cork being removed, the weight requisite to compensate its absence, gives the weight of the cork. This weight, being added to that which will compensate its buoyancy when immersed in water by being placed beneath the leaden disk in the lower scale, gives the weight of a quantity of water equal in bulk to the cork. Hence, if the number of grains representing the weight of the cork be divided by that representing the weight of its bulk of water, the quotient will be the specific gravity, which, in this case, must be expressed in a decimal fraction, as it is less than unity. SPECIFIC GRAVITY. 103 Method of ascertaining the Specific Gravity of Gaseous Substances. 599. Suppose the globe A, represented in the adjoining figure, to be removed from the receiver, R, and exhausted during a temporary attach- ment to an air-pump, by means of a screw with which the globe is furnished, and which serves also to fasten it to the receiver, as represented in the figure. Being preserved in this state of exhaustion by closing the cock, let it be sus- pended from a scale beam, and accurately counterpoised, as in a former experiment. (71 , &c.) In that experiment, after the globe was counterpoised, air was admitted and caused it to preponderate decidedly. If in lieu of admitting air, the globe be restored to the situation in which it appears in this figure, so as to be filled with hydro- gen from the receiver, R, and afterwards once more sus- pended from the beam, instead of preponderating decidedly as when air was allowed to enter, the additional weight ac- quired by it in consequence of the admission of the hydro- gen, will scarcely be rendered perceptible. Supposing, how- ever, that the additional weight thus acquired were detected, and also the weight gained by the admission of exactly the same bulk of atmospheric air, after a similar exhaustion of the globe, the weights of equal volumes of hydrogen and air would be repre- sented by the weights thus ascertained. The specific gravity of atmosphe- ric air is the unit, in multiples or fractions of which the specific gravities of the gases are expressed. Hence the weight of a given bulk of hydrogen, divided by the weight of an equal bulk of air, gives the specific gravity of hydrogen. By a similar process, the specific gravity of any other gas may be ascertained. Of the Influence of the Air on the apparent Weight of Bodies. GOO. A pleasant illustration of the loss of weight, and consequent inaccuracy at- tendant on the ordinary process of weighing, as conducted in the air, is afforded by the apparatus and process described in the next page. (001, &c.) 104 PONDERABLE MATTER. A Pound of Feathers heavier than a Pound of Lead. 601. If two bodies, one of which is more bulky than the other, be found equiponderant in the or- dinary process of weighing by a balance, the larger body is the heavier. 602. Let the bodies in question be those repre- sented within the receiver of an air-pump, in the annexed figure. On withdrawing the air by means of the pump, it will be found that the larger body preponderates, though previously counterpoised with accuracy. 603. Rationale. It appears from a preceding illus- tration, (573, &c .) that, when any body is surround- ed by a fluid, it is buoyed up with a force in propor- tion to the weight of the fluid, and the quantity displaced by the body. Of course, the more space it occupies in proportion to its weight, the more will its weight be counteracted. In the case of the two bodies rendered equiponderant in air, the weight of the larger is most counteracted by the air. Hence, on exhausting the air from the re- ceiver, the larger body shows a preponderancy over the other, equivalent to the superior support which the air had afforded it. 604. A similar result may be obtained, if hydro- gen be substituted in the receiver for atmospheric air; because, as its specific gravity to that of the air is only as 1 to 14 nearly, each body would lose 13-14ths of the support which the air had afforded ; but the larger body, having received more, would lose more. It follows, that the common saying, that " a pound of feathers is as heavy as a pound of lead," falls short of the truth; as they would really prove heavier were the air removed. Table of the Specific Gravities of the Principal Permanent Gases : also of the Weight of 100 Cubic Inches of each Gas. 605. This table is inserted here for convenient reference, not as an object of study collectively. Air Oxygen Chlorine Protoxide of chlorine Hydrogen Steam Chlorohydric (muriatic) acid Nitrogen - Nitrous oxide Nitric oxide Ammonia Sulphurous acid - Sulphydric acid (sulphuretted hydrogen) Carbonic oxide Carbonic acid - Carburetted hydrogen (light) Olefiant gas Cyanogen Chloroxycarbonic acid Fluosilicic acid Fluoboric acid Specific gravity at 60 degrees. Weight of 100 cubic inches in grains. 1 30.5 1.1111 33.8888 2.5 76.25 2.4444 74.5555 0.0694 2.1180 0.625 19.0620 1.28472 39.1839 0.9722 29.6527 1.5277 46.5972 1.04166 31.7708 0.59027 18.0035 2.2222 67.7777 1.1805 36.0069 0.9722 29.6527 1.5277 46.5972 0.5555 16.9444 0.9722 29.6527 1.8055 55.0694 3.4722 105.9020 3.6111 110.1385 2.3622 72.0471 (Page 105.) MODE OF COLLECTING AND PRESERVING GASES. 105 SECTION IV. DEFINITION AND DISCOVERY OF THE AERIFORM FLUIDS CALLED GASES. 606. It appears from the phenomena of calorific repulsion, that solid ponderable matter, by combining with caloric, first expands, next melts, and finally passes into that elas- tic state of fluidity, in which the repulsive power so far predominates over the attractive, that the particles recede from each other as far as external pressure will permit. When a substance is naturally aeriform, it is called a gas: when it retains the form of air only, in consequence of ex- traordinary (238,) heat, or a removal of pressure, it is called a vapour. 607. All gases were considered as common air, variously modified by impurities, until Dr. Black ascertained the na- ture of carbonic acid gas. Incited by this discovery, oxy- gen, nitrogen, hydrogen, chlorine, and many other sub- stances susceptible of the gaseous state, were discovered, or distinguished, by Scheele, Priestley, Cavendish, and others. Of the Art of Collecting and Preserving the Gases. 608. Cisterns filled with water or mercury, called hydro-pneumatic or mer curio-pneumatic according to the liquid employed, are used for collect- ing gases. The vessels intended to contain the gas are filled with water or mercury, and placed, in an inverted position, on a shelf, or part of the cis- tern, situated just below the surface of the liquid. As their orifices are not raised above the surface, they remain full of the liquid, in consequence of the pressure of the atmosphere. (86, 87, 132.) Any gas emitted under the mouth of a vessel, so filled and situated, rises to the top and displaces the contained liquid. Hydro-pneumatic Cistern. 609. In the Appendix will be found an engraving and description of a hydro-pneu- matic cistern, which I employed in the experimental illustrations of my lectures for more than ten years; and which I should probably continue to use now, had not the command of water from the public works, put it into my power to dispense with the mechanism for keeping the water at a proper level. As I am now situated, any de- ficit of water is easily supplied from the pipes known here as the hydrant pipes, by which the city is supplied with water; and any excess is carried off by a waste pipe. 610 A A, (see opposite engraving) is a water-tight platform, surrounded by a wood- en rim, R R R R, rising above it about an inch and a half. B, C, T, are three wells or cavities, each in the form of a hollow parallelepiped, with all of which the cavity bounded by the rim communicates; so that when supplied with water to the level of the waste pipe, this liquid fills the wells, and covers the platform to the depth of about fths of an inch. 611. E, F, G, are shelves, which severally move in grooves over the wells, so that they may be placed in the most convenient position. Under H is a waste pipe. At 14 106 PONDERABLE MATTER. I, is a winch which serves to let in water from the public reservoirs. K, is a pipe for emptying the wells and casks, with all of which, by means of cocks, it may be made to communicate when requisite. N, is a cask which acts as a gas-holder, hav- ing a communication with the cistern for letting in water from that source ; the ori- fices being controlled by valves. By means of a pipe proceeding from its vertex, the gas-holder communicates with a pipe or cock, at s, furnished with a gallows screw. To this, flexible leaden pipes may be attached, for transferring gas either from the gas-holder to a bell glass, or from a bell glass to the gas-holder. When a communi- cation is established between the cavities, either of these offices may be performed, accordingly as the pressure within the holder is made greater or less than that of the atmosphere. It will be greater when the valve for the admission of water is opened, that for letting it out being shut; and less when these circumstances are reversed. 612. Another cask with pipes and cocks, similar to that represented in the engrav- ing, is concealed by the pannel, O. 613. This cut affords a view of the lower side of the sliding shelf, in the wood of which will be seen two excavations, T, T, converging into two holes. This shelf is loaded with an ingot of lead at L, to prevent it from floating in the water of the cistern. Mercurio-pncumatic Cistern. 614. The following figure represents the mercurial cistern used in my laboratory. The front is supposed to be removed, that the inside may be exposed to view. IB 615. B B, is a wooden box, which encloses the reservoir so as to catch any of the metal which may be propelled over the margin of the cistern. This box is bottomed upon stout pieces of scantling, tenanted together and grooved so as to conduct the mercury towards one corner, where there is a spout to convey it into a vessel, situ- ated so as to receive it. The cistern itself is made out of a solid block of white marble. It is 27 inches long, 24 wide, and 10 deep. 616 The ledges, S S, answer for the same purposes as the shelves in the hydro- pneumatic cistern described in the preceding article. The excavation, w, constitutes the well. In this well vessels are filled with mercury, in order to be inverted and placed while full on the ledges. There are some round holes in the'marble for in- troducing upright wires to hold tubes or eudiometers ; also some oblong mortices for allowing the ends of tubes, duly recurved, to be introduced under the edges of ves- sels to be filled with gas, and in cases of rapid absorption, to afford a passage for the mercury into vessels, into which its entrance might be impeded, in consequence of their close contact with the marble of the reservoir. To fill this reservoir requires nearly 600 pounds of mercury. Large Gasometer for Oxygen. 617. The opposite engraving represents a section of my gasometer for oxygen or other gases, which is capable of holding between eight and nine cubic feet of gas. It is represented as it was situated, when the drawing was made, in the cellar under my lecture room. It is now placed in the lecture room in front of my table, near one end. The wooden tub, V, is necessarily kept nearly full of water. The cylin- drical vessel, T, of tinned iron, is inverted in the tub, and suspended and counter- poised by the rope and weight, in such manner as to receive any gas which may proceed from the orifice of the pipe in its axis. This pipe, passing by means of a water-tight juncture through the bottom of the tub, is extended to a cock fixed in a Large Gasometer for Oxygen. (Page 100.) OF SIMPLE PONDERABLE ELEMENTS. 107 cavity made in the plank forming the rim of the pneumatic cistern. Hence by means of this cock, and a leaden pipe soldered to a brass knob, properly perforated, a communication may be established between the cavity of the gasometer and any other vessel, for the purpose either of introducing or withdrawing gas. In filling this gasometer, the copper vessel and bell glass, used in obtaining nitrous oxide, may be employed advantageously; -or the counter-weight being made heavier than the vessel by appending additional weight to the rincr, K, the gas may be sucked in from a bell glass, situated over the pneumatic cistern, as fast as it enters the bell from the generating apparatus. CIS. As the gas displaces the water from the cavity of the vessel, T, the latter becomes more buoyant, and consequently rises. When any gas is withdrawn or expelled, the water resumes its place, and the vessel sinks. G19. Gasometers which contain 40 or 50,000 cubic feet have been ponstructed upon this principle for holding the gas from oil or coal. They are usually hollow parallel- epipeds. The upper vessel is generally made of varnished sheet iron, the lower one of brick-work or cast iron. The space within the lower vessel, which is included by the upper one when down, is filled up, so as to lessen the quantity of water re- quired. (See article on carburetted hydrogen.) INORGANIC CHEMISTRY, OR CHEMISTRY OF INORGANIC SUBSTANCES. OF SIMPLE PONDERABLE ELEMENTS, THEIR REACTIONS WITH EACH OTHER, AND THE RESULTING COMBINATIONS. 620. Having in the preceding pages treated of certain general properties of ponderable matter, or those means of ascertaining or observing them of which a knowledge is indispensable to a chemist, I shall, in the next place, proceed to the consideration of ponderable substances individually, and their reactions and combinations with each other. 621. In treating of ponderable elements and their multifarious compounds, various arrangements have been pursued by different writers. Some have preferred to begin with elements, and to proceed to compounds; others to begin with compounds, and to proceed to elements. In favour of the last men- tioned course, it may be alleged, that the most interesting substances in nature become known to us at first, in a state of combination. Thus, for instance, the air, water, salts, acids, alkalies, also flesh, sugar, farina, and other or- ganic products, valuable either as food or as medicine, are compounds which have been naturally made the subjects of chemical inquiry ; and it may be inferred that the student might with advantage be induced to travel in those paths, of which a successful pursuit has led to that chemical knowledge which it is the object to impart. In this way he proceeds from facts which he knows, to such as he ought to learn, in the order in which he would spontaneously advance as far as he might be competent. But it may be objected, that no sooner are the ingredients of a body stated, than the stu- dent is distracted by names, of which he is ignorant; and which there is an immediate necessity to explain. Hence it follows that the ingredients of a compound may come to be considered in immediate succession, when they may have no analogy with each other; while it is highly advantageous, after having treated of any one element, to proceed to that which has the greatest analogy with it. In that case, a certain portion of the conceptions which have been formed respecting one element, may be extended to ano- ther, with little mental exertion, and without much additional pressure upou the memory. 108 INORGANIC CHEMISTRY. 622. The method first mentioned of treating of each elementary sub- stance first, and afterwards of compounds, is objectionable, because it cannot be put into practice effectually. To treat of the chemical habitudes of any one element, requires that we should speak of other elements, in reacting with which, those habitudes are displayed, and respecting which a beginner is of course ignorant. In pursuing this course, each substance must be treated of imperfectly, or language and illustrations employed, which the student is unprepared to understand. 623. The course which I have chosen is as follows. I begin with the ele- ment which, of all ponderable matter, has the most important part assigned to it in nature ; I mean oxygen. The history, state of existence in nature, means of procuring, and properties of this substance, so far as they can be rendered intelligible to a novice, are stated, or exemplified and explained. In the next place to oxygen, I present chlorine to attention, which has at least as much analogy with oxygen, as any other known element, and is, at the same time, an agent of high importance. Having treated separately of oxygen and chlorine, as far as may be expedient, the compounds which they form with each other, may, in the next place, to a certain extent, be treated of with advantage. Then, guided by analogy, bromine and iodine, though inferior in importance, may be successively treated of, and subse- quently all the compounds which they can form, either with oxygen or chlo- rine, or with each other. This system will be followed in treating of all the elements. 624. Pursuant to this method, little can be said of fluorine in the section appropriated to its consideration, since those elements with which its most interesting reactions take place, cannot consistently be made the object of attention under that section. 625. Cyanogen is, in its properties, analogous to chlorine, bromine, and iodine, yet being composed of carbon and nitrogen, should not be an object of attention, until the pupil is prepared by a knowledge of its said constituents. Besides, it comes in consistently under the general head of carbon, which, agreeably to my plan, as above explained, comprises the compounds of carbon with all substances previously treated of, among which is nitrogen. 626. Of the fifty-four simple elements universally recognised by che- mists, a list, with their equivalent numbers and symbols, has already been given. (560, &c.) 627. Of these elements, chlorine, bromine, iodine and fluorine are classed by Berzelius under the name of halogen bodies, or generators of salts ; while oxygen, sulphur, selenium, and tellurium are classed together under the name of amphigen bodies, or both producers ; meaning that they are pro- ductive both of acids and bases. To the elementary halogen bodies, he adds the compound body cyanogen. I object to this classification, that the word salt admits of no definition, reconcilable with the use which has been made of it by the distinguished author; arid because, from facts and defi- nitions practically sanctioned by him, and chemists in general, it is evident that the elements belonging to both of his classes are productive of acids and bases. Hence I have associated them in one class, under the appella- tion of basacigen elements* In honour of Berzelius, I shall, however, re- tain the terms halogen and amphigen, in order to designate the elements which he has distinguished by those names. It may be proper to add that we owe to Berzelius himself the idea that any other substance besides oxy- gen could form acids and bases capable of uniting to form salts. Our OF SIMPLE PONDERABLE ELEMENTS. 109 knowledge of the existence of this faculty in three of his amphigen ele- ments, sulphur, selenium and tellurium, is, I believe, entirely due to his investigations. If chemists, myself among others, who consider his double salts as consisting of acids and bases, are in the right, it is to the light af- forded by his brilliant discoveries that we owe the ability to pursue the true path. 628. Before concluding this preliminary exposition of the classification and nomenclature which I propose to adopt, I wish to make it clear, that the attribute of producing both acids and bases, which, agreeably to the plan of Berzelius, is restricted to his four amphigen elements, is, agreeably to mine, extended to the elements comprised in both of his classes, which are consequently united under one designation, as basacigen elements. My basacigen class is, therefore, the amphigen class of Berzelius, enlarged under a new and more descriptive name,* so as to take in both of his halogen and amphigen classes. 629. In order to render the definition of a basacigen body precise, it may be necessary that I should give a definition of acidity and basidity.f 630. I shall proceed to give a definition which to me appears quite satisfactory. It is perhaps necessary to premise, that a tertium quid was, agreeably to the old chemists, a compound in which the qualities of the ingredients were neutralized, or so much altered, as to make a body capable of a chemical reaction differing from that of either of its ingredients. It means, therefore, a third something, a " tertium quid." But to proceed to the definition; it is as follows. 631. When of two compounds capable of combining together to form a tertium quid, and having an ingredient common to both, one prefers the positive, the other the negative pole of the voltaic series, we must deem the former an acid, the latter a base.$ 632. Thus sulphuric acid, (consisting of sulphur in combination with oxygen,) and soda, (consisting of sodium and oxygen,) are capable of com- bining to form sulphate of soda, a tertium quid. Each of these compounds have a common ingredient, oxygen, and one of them, the acid, prefers the positive pole of the voltaic series, the other the negative pole. It follows, that sulphuric acid is entitled to the appellation of an acid, while soda may claim that of a base. * It will, I trust, be perceived, that a basacigen element is one capable of pro- ducing both an acid and a base, the monosyllable gen being understood, in chemical language, when added to a word expressive of a property, or state, to signify the ' power of producing that property, or state. (633.) t As a name is much needed to convey the idea of the basic property, as acidity does of the acid property, I have ventured, without any authority, to em- ploy the word basidity, which from its analogy with acidity, must, I presume, be intuitively intelligible. t I wish it to be understood, that I consider this definition as only declaratory of the practice of chemists, who all obey the rule, although, as far as I know, excepting by myself, it has never been enunciated. I do not deem it necessary to introduce into the text a corollary, which in- evitably flows from the cited definition, as it would unnecessarily distract atten- tion ; but it may be well before taking leave of this subject, to say, that agreeably to universal practice, any body which is capable of saturating a base, is considered as an acid ; and that on the other hand, any body which is capable of saturating an acid, is inferred to be a base. It is upon this basis that the pretensions of the or- ganic alkalies and acids to be considered as acids or bases, are founded. 110 INORGANIC CHEMISTRY. OF INDIVIDUAL PONDERABLE ELEMENTS, AND OF THEIR REACTION WITH EACH OTHER, AND THE RESULTING COMPOUNDS. 633. Classification. Of the fifty-four elements enumerat- ed, (627,) eight being designated as basacigen, make, with cyanogen, the compound basacigen body, (629,) nine in all, in the basacigen class. I shall designate the rest of the elements as radicals; subdividing them into metallic radicals, and non-metallic radicals. OF BASACIGEN ELEMENTS. 634. Oxygen, Cyanogen, Chlorine, Sulphur, Bromine, Selenium, Iodine, Tellurium. Fluorine, They will be treated of in the order in which they have been named, in the eight following sections. 635. I have already stated that in honour of Berzelius I should employ his appellations amphigen and halogen. There is, in fact, a necessity for words to distinguish the bodies to which he has applied these names; especially from the very great analogy between those which are de- signated as halogen. 636. The student is requested to recollect that chlorine, bromine, iodine, fluorine and cyanogen constitute the ha- logen class of Berzelius, while oxygen, sulphur, selenium and tellurium form his amphigen class. SECTION I. OF OXYGEN. 637. In the gaseous state, oxygen forms one-fifth of the atmosphere in bulk ; and as a constituent of water in the ratio of eight parts in nine, it pervades every part of the creation where that important compound is to be found. It exists in that congeries of oxidized matter which we call earth, and is a principal and universal constituent of OXYGEN. Ill animal and vegetable matter. Its combinations with me- tals and various other combustibles are of the highest importance in the arts. It was called oxygen under the erroneous impression of its being the sole acidifying prin- ciple, from the Greek ofa acid, and y">. About twenty grains of phosphorus being placed upon the copper disk, a glass globe is put over it upon the plate ; and by causing one of the pipes which are attached laterally to the cylinder to communicate with an air pump in operation, the globe is exhausted. By means of the other pipe, a due quantity of oxygen gas is then let in from the bell glass, B, to which this pipe is annexed. The apparatus being thus prepared, the end of an iron rod previously reddened in the fire, is passed through the bore of the tube so as to touch the copper disk which holds the phos- phorus. The most vivid ignition ensues. The light has at first a dazzling beauty, but is soon " shorn of its beams" by the dense white fumes of phosphoric acid, which the combustion evolves- Hence, an effulgence, approaching to solar brilliancy, soon yields to a milder illumination like that of the moon, rendered more pleasing by the contrast. 656. The globes with which I am accustomed to perform this experiment contain about 15 gallons. It is better that the gas in the globe should be in some degree rarefied; otherwise the expansion at first excites a considerable effort in the air to escape. The enlargement of bulk, arising from the heat, may be provided for by a bag or bladder, a communication with which being opened, a portion of the heated gas is enabled to retire, till the condensation of the oxygen with the phosphorus, into phosphoric acid, compensates the expansion. 657. I have performed this experiment, when the density of the gas was one-half less than if in equilibrio with the atmospheric pressure. This of course obviated the possibility of any ill consequences from expansion. Combustion of Sulphur in Oxygen Gas. R 116 INORGANIC CHEMISTRY. 658. Supposing the junctures made by the plates, P />, with the receiver, R, to be air-tight, and that there is a communication between it and the bell glass, B, by means of a flexible leaden pipe, L, it must follow that, whenever the suction pump, from which the recurved pipe, S, terminating within the bell, proceeds, is made to act, the air in B being rarefied, that in R will force its way through L, and the liquid in the vase upon the stand. It must also be evident that, if the pipe and cock, C, communicate, on one side with the receiver, on the other with a reservoir of oxygen, this gas will be impelled into the receiver, as soon as the cock is opened, in order to restore the equilibrium destroyed by the suction pump. 659. The plate, P, with its supporting hollow brass cylinder, has been already de- scribed in the preceding article. The tube, surmounted by the disk, used in the combustion of phosphorus, is removed, and in its place a piece of a gun barrel is, in like manner, fastened, so that the butt-end may occupy the axis of the cylinder. The touch-hole being closed, a perforation, similar in size, is drilled in the end of the barrel, at the point from which the flame is represented as proceeding in the figure. In order to produce this jet of vaporized sulphur, some cotton wick is wound about the end of a rod, and tied on it. The tuft, thus made, is soaked in melted brimstone. The gun barrel, during a temporary removal, is heated red-hot at the butt-end, where it is perforated. Being screwed into its place again, the rod, armed with the cotton and sulphur, is pushed up into the bore of the barrel. By the heat of the iron, the sulphur is converted into a hot vapour, which, issuing in a jet from the perforation, enters into combustion with the oxygen in the receiver. 660. In consequence of the rarefaction of the air in the bell, B, by the suction pump, the fumes of the burning vaporized sulphur are drawn through the water in the vase upon the stand, in which, consequently, a mixed solution oT sulphuric and sulphurous acids is produced. Additional Illustration of the Combustion of Sulphur in Oxygen. 661. The preceding illustration has not for two or three years, been exhibited before my class, yet presuming it might not be uninteresting to some of the students of this work, I have not omitted it from this edition. Lat- terly I have resorted to the following method of exhibiting the combustion of sulphur in oxygen, as being easier, and yet sufficiently pleasing and instructive. All the steps of the process for the combustion of phosphorus in oxygen are performed, as already described (651, &c.) but in lieu of a stick of phosphorus, a tuft of asbestos soaked in melted sulphur, is placed upon the capsule, with a minute piece of phosphorus beneath it. The latter when heated by the incandescent iron takes fire, and consequently ig- nites the sulphur, with which the asbestos is imbued. In whiteness and dazzling brilliancy, the light afforded by the combustion of sulphur in oxygen is inferior to that evolved by phosphorus, when similarly situated; but this inferiority is compensated by the splendour of its characteristic pur- ple hue. CHLORINE. 117 SECTION II. OF CHLORINE. 662. As a gas, chlorine exists only by artificial means; but as an ingredient in marine salt, in the proportion of three-fifths, it constitutes nearly one-fiftieth of the matter in the ocean, and is widely disseminated throughout the land as well as the sea. It is also an ingredient in some of the most active agents used in chemistry or medicine. It was discovered by Scheele, and called by him dephlogis- ticated marine acid. It afterwards received the name of oxygenated muriatic acid, or oxymuriatic acid, from La- voisier and the chemists who "adopted his nomenclature, under the erroneous idea that it was composed of muriatic acid and oxygen. Its present name was given by Sir H. Davy, from ^A^ green, because its colour is greenish. 663. Preparation. It is obtained by heating in a retort or alembic, of glass or lead, three parts of black oxide of manganese, with four parts of muriatic acid; or the same quantity of this oxide, with eight parts of common salt, four parts of sulphuric acid, and four parts of water. 664. Being a gas, chlorine must be received over the hydro-pneumatic cistern in bell glasses or bottles; the tem- perature of the water should be raised, by adding a por- tion boiling hot. As much of it is absorbed if it remain long in contact with the water, I generally employ glass bottles with air-tight stopples, in order that they may be removed from the water as soon as filled. Berzelius al- leges that if the water employed be saturated with salt, there is less absorption. 665. Jars or bottles may be filled with chlorine gas, by means~ of a tube or retort beak, as in fig. 1, of the follow- ing engraving, reaching from the generating vessel to the bottom of that into which it is to be introduced. The air is displaced by the chlorine, in consequence of its superior gravity, without any admixture ensuing adequate to inter- fere with the exhibition of its characteristic properties. 666. When substances which take fire in the gas are to be introduced, it is expedient that a communication should exist with the inside of a bladder attached, as in the fol- lowing figures, which represent apparatus, of which fig. 1 may be used for the combustion of metallic powders, fig. 118 INORGANIC CHEMISTRY. 2 for that of phosphorus, introduced by means of the la- dle L. Fig. 1. 667. Properties. When pure and dry, chlorine is a per- manent gas of a greenish-yellow colour. Its weight to that of common air, is nearly as two and a half to one. Even when existing in the air in very small proportion, it is intolerable to the organs of respiration, and to respire it pure, would quickly produce fatal consequences. 668. Mr. Faraday has shown that, under great pressure, chlorine becomes a liquid. It will remain liquid some in- stants after all pressure is removed, in consequence of the great cold produced by its evaporation. 669. That species of chemical action which is attended with the phenomena of combustion, is supported by this gas with great energy. It combines directly with every combustible except carbon. It has a curious property, first noticed by me I believe, of exciting a sensation of warmth ; though a thermometer, immersed in it at the same time, CHLORINE. 119 does not indicate that its temperature is greater than that of the adjoining medium. The heat thus noticed is proba- bly produced by a reaction with the matter insensibly per- spired. 670. Chlorine is absorbed by water, and the solution acts powerfully on metals. It appears to be the only sol- vent of gold. At the temperature of 40, it forms with water a solid hydrate, consisting of 1 atom of chlorine, and 10 atoms of water. Silver, in solution, is the best test for chlorine; and, reciprocally, chlorine is the best test for dissolved silver. The compounds of chlorine with mer- cury, so useful in medicine, will be treated of when on the subject of that metal. When the aqueous solution of chlorine is exposed to the solar rays, it forms muriatic acid with the hydrogen of the water, while the oxygen escapes. It bleaches by liberating the oxygen of water, and thus enabling it to act on the colouring matter. Although it has no direct reaction with oxygen, when in their nascent state, these elements unite to form four com- pounds, all of which are now considered as acids. 671. About thirty years ago, chlorine gas was univer- sally considered as a compound of muriatic acid and oxy- gen, and called oxymuriatic acid. It is now deemed an elementary substance, rendered gaseous by caloric. Experimental Illustrations of the Properties of Chlorine. 672. Leaves of Dutch gold, introduced by means of a glass rod into a bottle of chlorine, take fire. 673. Calorific influence upon the fingers compared with that upon a thermometer. 674. An infusion of litmus whitened in descending in a stream through the gas from a funnel. 675. A lighted candle introduced, burns with a carbo- naceous flame. Combustion of Antimony in Chlorine. G7l5. When an air pump is at hand, the following apparatus may be used for the )mbustion of powdered antimony. It consists of a large ' supported in the screw rod and plate frame described. (248.} combustion of powdered antimony. It consists of a large jar closed air-tight, and ipported in the screw rod and plate frame described. (248.) 077. By means of one of the flexible pipes and cocks with which the apparatus is furnished, communication may be made with an air pump, and with a large vessel, A B, containing chlorine. Into the centre of the lid a cock is fastened, the key of which, instead of being perforated as usual, is drilled only half through, so as to pro- duce an excavation capable of holding a thimbleful of powder. The cavity in the key of the cock is charged with pulverized antimony, which, on turning the key half round, falls through the chlorine, and as it falls assumes the appearance of a shower 120 INORGANIC CHEMISTRY. of fire. The cock being, from its construction, always closed, and the junctures being tight, the spectators are protected from the noxious fumes. 678. In this experiment^the chlorine forms with the antimony a compound which has less capacity for caloric and light than its ingredients have separately. Hence, by their combination, the phenomena of combustion are produced. The product of the combustion is the perchloride. Apparatus for the Combustion of Metallic Leaf* in Chlorine. , 679. The apparatus used in this experiment (See fig. 1,) differs but little from the one above represented, (677, &c.) being the same as that described in page 43 3 (241, &c.) excepting the funnel, which is unnecessary in this case. 680. Into the lower end of the cock a rod of iron is screwed fast. This rod is of such dimensions as to extend from the top to the bottom of the receiver, and is sup- ported within it, so as to be in its axis or every where equidistant from the surface. Before fastening the plate into the situation in which it is represented in the figure, it must be lifted in order to attach the leaf metal to the rod with the aid of gum arable. The arrangements being so far completed, the cylindrical receiver having been exhausted by means of the air pump, the cock, regulating the communication with that instrument, is to be closed, and the other which controls the entrance of the gas is to be opened. By these means the leaves burn splendidly, being simulta- neously enveloped in an atmosphere of chlorine, which rushes in to supply the va- cuum caused by the air pump. * The metal usually employed is the Dutch gold leaf of the shops, an alloy prin- cipally of copper and zinc. CHLORINE. 121 681. Another method of performing this experiment is illustrated by fig. 2. FIG. 1. FIG. 2. 682. The metallic leaves being suspended from the plate which closes the bell, B, and this bell being exhausted of air by means of the pump, chlorine is suddenly ad- mitted into it by the glass cock from the bell glass, A, previously supplied with the gas. Spontaneous Combustion of Phosphorus in Chlorine. 683. The figure at the top of the next page, is intended to convey an idea of the spontaneous inflammation of phosphorus in chlorine, by means of an apparatus which enables the lecturer to perform the experiment without exposing spectators to the fumes. Let there be a cylindrical glass vessel, eight or nine inches in diameter, and about a foot in height, with a neck about four inches high, and one and a half inches in bore ; the whole resembling a large decanter without a bottom, About the orifice of the neck, let there be cemented, air-tight, a brass cap, sur- mounted by a stuffing box, and having on one side a hole communicating with the cavity of the neck. This aperture must be furnished with a screw, by which it may be opened or closed at pleasure. Through the stuffing box a copper rod passes, at the lower end of which a glass or leaden stopple is so affixed, as to close the low- er part of the neck, into which it is ground to fit air-tight. Over this stopple, a cup of copper is soldered, so as to be concentric with the rod. The rod terminates above in a handle. Within the cup, let ten or fifteen grains of phosphorus be placed. This is easily effected when the cup and plug are depressed into the lower part of 16 122 INORGANIC CHEMISTRY. the cavity of the vessel, by a suitable movement of the sliding rod. In the next place draw up the cup and plug into the neck, so as nearly but not entirely to close it, and sink the vessel into the water of the pneumatic cistern until all the air below the neck is expelled through the hole in the side of it, which is then to be closed by means of the screw, and the plug twisted and drawn into its place, so as to be air- tight. After filling the body of the vessel thus with water, place it upon the shelf of the cistern. Chlorine may now be allowed to occupy three-fourths of the space within the vessel below the plug. The process being so far advanced, it is only ne- cessary, at the moment when it is desirable to produce the combustion, to depress the plug, and of course the cup associated with it containing 'the phosphorus, into the cavity supplied with the chlorine . The phosphorus soon burns actively, although with a feeble light. The increased temperature consequent to the combustion, causes the gas to expand, but not so much as to become too bulky to be retained. 684. In this case the chlorine forms a chloride of phosphorus, which, meeting with water, is decomposed into phosphoric and muriatic acids. By transferring the vessel, after it is supplied with chlorine, to a clean porcelain or glass dish, covered with pure water, the products of this combustion might be saved, and would of course in- crease in proportion to the quantity of phosphorus and chlorine employed. On a larger scale, this process might be resorted to advantageously for the generation of phosphoric acid, which is produced when the proportion of chlorine is sufficient; say four cubic inches for every grain of phosphorus. Of the Compounds of Chlorine with Oxygen, and of the Nomenclature of these Compounds and others formed with the Basacigen Class. 685. Consistently with the French nomenclature, the combinations formed by oxygen, chlorine, bromine, iodine, and fluorine, with other elements, have been distinguished as acids, or characterized by a termination in " ide" or in " ure? which last monosyllable, when there has been no in- tention of altering the meaning, has, by the British chemists, been translated CHLORINE. 123 into uret. The termination in ide, which is common to both languages, is, by Thenard, and other eminent French authors, restricted to the binary com- pounds of oxygen which are not acid. Analogous compounds formed with the halogen elements, chlorine, bromine, iodine, fluorine, cyanogen, &c., have by the same writer been designated by the termination in ure. Thus we have in his work, chlorures, bromures, iodures, fluorures, and cyanures. Some of the most eminent chemists in Great Britain have distinguished the elements called halogen by Berzelius, together with oxygen, as sup- porters of combustion, and have designated the binary compounds made with them, when not acid, by the same termination as the analogous com- pounds of oxygen. Accordingly, in their writings, instead of the names above mentioned, we have chlorides, bromides, iodides, fluorides. In Hen- ry's Chemistry, cyanure is represented by cyanide ; in Thomson's, by cyan- odide ; and in Brande's and Turner's, by cyanuret. I shall follow the prac- tice of the British chemists in the case of the four first mentioned com- pounds, extending it to the compounds of cyanogen, as Henry has done. 686. These rules of nomenclature will be considered as extending to all the basacigen class. Of course, the compounds of sulphur, selenium and tellurium, when not acid, will be designated by appellations terminating in ide. In lieu, therefore, of sulphuret, selenuret and telluret, I shall in com- mon with Berzelius, employ the words sulphide, selenide and telluride. COMPOUNDS OF CHLORINE WITH OXYGEN. With 1 atom, or volume of oxygen, or hypochlorous acid, ....--- 44 687. 1 atom or 1 volume of chlorine equivalent 36, forms With 4 atoms, or 2 volumes of oxygen, chlorous acid, - 68 With 5 atoms, or 2^ volumes of oxygen, chloric acid - - 76 With 7 atoms, or 3| volumes of oxygen, perchloric, or oxychloric acid, - 92 Of Hypochlorous Acid. 688. This compound, of which the ingredients are stated above, (687,) is generated by the reaction of chlorine, with an excess of finely pulverized peroxide of mercury, suspended in pure water by agitation. 689. By these means, the chlorine, agreeably to the 4th case of affinity, (523, &c.,) combines with both the oxygen and mercury, forming two com- pounds, a bichloride of mercury, and a protoxide of chlorine, or hypochlo- rous acid, which dissolves in the water. The bichloride combines with a portion of the undecomposed bioxide, and forms a kind of combination, generically designated as oxychloride, indicating that a substance so called consists of an oxide, and a chloride. " The oxychloride formed in this case, being almost insoluble, is separated by filtration. A more concentrated so- lution of the acid is procured by successive distillations, in which as little heat as possible should be used, and preferably it should be accomplished by diminished pressure.*' 690. Properties of Hypochlorous Acid. The aqueous solution of hy- pochlorous acid, resulting from the above described process, is, when con- centrated, in colour slightly yellow, with an odour strong and penetrating, * For the purpose of distillation, by reduced pressure, the apparatus represented and described in page G9, (398,) might be used, substituting a second and third re- tort, well refrigerated, for the vessel, B, and the bottle, C. (188.) 124 INORGANIC CHEMISTRY. resembling that of chlorine, but yet differing therefrom perceptibly ; upon the skin its effects are similar to those of nitric acid, but more active. Its bleaching powers are eminently great. It is so much prone to decomposi- tion, as to undergo that process spontaneously at ordinary temperatures, beinff resolved into chlorine and chloric acid. This change is accelerated by light, and ensues immediately from direct exposure to the solar rays. Bodies full of sharp corners, (the fragments of powdered glass, for instance,) when thrown into the liquid acid, are productive of an evolution of chlorine with brisk effervescence. The oxydizing powers of this reagent are pow- erful but various, being most active with non-metallic elementary radicals, such as sulphur, phosphorus, and selenium. Each of these it readily satu- rates with oxygen, and likewise iodine, and bromine, which are thus seve- rally converted into bromic and iodic acid. Its reaction with gold and pla- tinum, is but feeble, but with iron and silver energetic. The former is con- verted into an oxide, the latter into a chloride, while in the case of the one, the oxygen escapes, in that of the other the chlorine. Mercury it converts into an oxide, and a chloride, which form an oxychloride, by uniting in their nascent state. Of Gaseous Hypochlorous Acid. 691. Balard, to whom we are indebted for our knowledge of the facts above stated, was successful in procuring hypochlorous acid in the gaseous form, by introducing into a concentrated aqueous solution over mercury, anhydrous nitrate of lime in successive portions. By its superior affinity for water, the nitrate causes the evolution of the acid in the aeriform state, , the mercury being protected by the interposed solution of the nitrate. 692. Properties of Gaseous Hypochlorous Acid. The gaseous hypo- chlorous acid much resembles chlorine, in possessing a greenish yellow colour. Water absorbs 100 times its own volume of it. 693. A slight increase of temperature is sufficient to cause hypochlorous acid to detonate, and though less explosive than chlorous acid, it is apt to explode, when an effort is made to transfer it from one bell glass to another. 694. Its composition was ascertained by Balard, by analyzing the gas- eous product resulting from its explosion, by which it was found to consist of one volume of chlorine, and half a volume of oxygen, as already stated. (638.) Of Euchlorine or Impure Chlorous Acid. 695. In the last edition of this work, euchlorine was treated as a prot- oxide of chlorine, but it was, at the same time mentioned, that doubts ex- isted whether the gaseous substance known by this appellation, might not be a mixture of chlorous acid with chlorine. These doubts appear to have been succeeded by an affirmative conviction, and accordingly I have omit- ted the name from the list above given, of the definite compounds of chlo- rine with oxygen. 696. Euchlorine is obtained by heating gently, in a small glass retort, equal parts of strong muriatic acid, water, and chlorate of potash. The retort should only be subjected to the flame of a small spirit lamp, or an inflamed jet of hydrogen, which should be so situated as not to heat the body of the retort above the part containing the liquid ; as this may cause an explosion. It is advantageous to interpose, as a support for the retort, a plate of tin, having a circular aperture of about an inch and a half in diameter. By these means, the application of the heat may be sufficiently restricted. CHLORINE. 125 697. The gas may be received over mercury, although not without inconvenience; since by its decomposition, in consequence of the large pro- portion of free chlorine with which it is associated, the mercury is super- ficially converted into a subchloride. But, while the covering thus formed, protects the surface of the metal from further erasion, it also, by coating the internal surface of the glass, hides, more or less, the remarkably deep greenish-yellow colour of the gas from the eye of the spectator. 698. Agreeably to Soubieran, when the gas thus obtained is passed through a tube, replete with protochloride of mercury, (calomel,) this chloride absorbs an additional atom of chlorine, and thus brings the chlo- rous acid to a state of purity. The rationale of the evolution of the mix- ture known as euchlorine, seems to be as follows. By double elective affinity, there is a reciprocal decomposition of the potassa and chlorohydric acid, causing the separation of the chloric acid, containing five atoms of oxygen. Consequently, by the reaction with these atoms, a further dehy- drogination of chlorine ensues, causing a portion to be set free, while another portion retains enough oxygen to constitute chlorous acid. Process for elaborating pure Chlorous Acid directly. 699. Pure chlorous acid is obtained by distilling one part of chlorate of potash, fused into a mass, at the bottom of a small glass retort, with about 3^ parts of concentrated sulphuric acid, and receiving the gaseous product over mercury. The evolution of the gas takes place without heat at first, but to be completed requires a temperature near to 140. This should not be exceeded, and the heat should be restricted to the bottom of the retort, as in the case of euchlorine. The process is replete with danger, as from slight causes this gas explodes with surprising force. 700. Rationale. By the action of sulphuric acid on chlorate of potash, two compounds are produced, chlorous and oxychloric acid. The former is evolved in the gaseous state, the latter remains in union with the potash. It would seem as if one portion of the chloric acid were displaced from its union with the potash by the superior affinity of the sulphuric acid, and then relinquished a part of its oxygen to another portion of the same acid, still in union with the alkali. The chlorate of potash is thus partially converted into an oxychlorate. The deoxidized chloric acid constitutes a compound which is designated by Berzelius as chlorous acid. By others, it has been variously designated as the tritoxide, quadroxide, or peroxide of chlorine, in consonance with the different impressions entertained of its properties, or composition. Properties of pure Chlorous Acid. 701. Chlorous acid gas has a yellow colour, which is deeper than that of chlorine. Its odour is somewhat aromatic, and bears no resemblance to that of chlorine. It whitens a solution of litmus, without reddening it. When subjected to an electric spark, or to a temperature of 212, it ex- plodes with great violence, giving out light and heat, and being converted into chlorine and oxygen. Agitating the gas with mercury will sometimes produce the same result. Water absorbs seven times its volume of chlorous acid gas, acquiring a deep yellow colour, and a peculiar acrid taste, which is nevertheless not at all acid. The aqueous solution, when added in small quantities, possesses the power of reddening litmus, and when exposed directly to the sun's rays evolves chlorine, while oxychloric acid remains in solution. In a diffuse light it takes several weeks to effect this decom- position, and it does not take place at all in the dark. Faraday has found 126 INORGANIC CHEMISTRY. that chlorous acid gas may be liquefied by subjecting it to great pressure, The resulting liquid is of a yellow colour. A convenient and safe Method of effecting the Explosion of Euchlorine. 702. A convenient and safe method of effecting the explosion of euchlorine per se is represented in the preceding figure. The gas being .introduced into a strong tube of about ths of an inch in diameter, and fifteen inches in length, over mercury, on applying a heated metallic ring, an explosion ensues. The gas at the same time loses its greenish-yellow colour, and increases in bulk. The chlorine is subsequently absorbed by the mercury. 703. Thenard advises the application of a spirit lamp to produce the necessary temperature. It is easier and more safe to use the hot ring. The tube is of neces- sity supported by an iron wire, which has been overlooked in sketching the figure. 704. Rationale. Agreeably to the idea that aeriform fluids owe their repulsive power to caloric, there ought, after an evolution of heat, to be a reduction of volume in any gaseous compound; but by the decomposition of euchlorine, although caloric is evolved with explosive violence, the volume of the gaseous matter is increased. 705. The only explanation which I can give, is, that the capacity for caloric of the compound in this case, as in others, is greater than the sum of the capacities of the constituents. Why the capacity of the compound should be greater, and wherefore caloric should be more forcibly attracted by an atom of oxygen and an atom of chlo- rine when united than when separate, I cannot explain. This and other analogous mysteries are no doubt connected with those of electricity, galvanism, and electro- magnetism. Apparatus for exhibiting safely the Explosion of Chlorous Acid. 706. The adjoining figure represents an apparatus for exhibiting, without danger to the spectators, the detonation of chlorous acid. 707. Into a tube of nearly f ths of an inch in dia- meter, and sealed at one end, about as much chlorate of potash is introduced as will rise above the bottom about one inch. The mass thus situated is to be fused by means of a spirit lamp, or chauffer. 708. The tube, being then charged with a due proportion of sulphuric acid, is corked gently, and suspended within a stout glass cylinder, as in the drawing. It is then surrounded, near the bottom, by another tube, supplied with boiling water. At first, the hot water is applied only to that part of the tube which contains the salt; but as soon as the inner tube is pervaded by a greenish-yellow colour, de- monstrating the evolution of the chlorous acid, the outer tube containing the water is to be raised, so that the gas may be generally heated by it. An explosion soon follows, from the influence of which spectators are protected by the glass cylinder. Preparation of Chloric Acid. 709. When a solution of potassa (oxide of potassium) or the carbonate of this alkali is CHLORINE. 127 impregnated copiously with chlorine, crystals precipitate, which consist of chloric acid in union with potassa. If to a solution of the chlorate of potassa thus formed, fluohydrosilicic acid be added, an almost insoluble fluosilicate of potassium precipitates. From this an aqueous dilute solu- tion of the desired acid may be obtained by filtration. 710. If, in lieu of a solution of potassa, water holding baryta suspended, be impregnated with chlorine, a chlorate of baryta may be procured, from which the baryta may be precipitated by employing, as nearly as possible, an equivalent of sulphuric acid. It was by this process that Chenevix discovered chloric acid ; but it is alleged that when thus procured, it retains a minute proportion of sulphuric acid. ' 711. Properties. Chloric acid, thus procured, is inodorous, colourless, sour and astringent. It does not precipitate solutions of lead, mercury, or silver, which, for a great majority of the compounds of chlorine, are infal- lible tests. When concentrated by evaporation, at a gentle heat, it is re- duced to an oleaginous consistency, and acquiring a yellowish tint, also an odour like that of nitric acid. In this state it ignites paper, and other or- ganic products, and is capable of converting alcohol into acetic acid. It is decomposed by many substances having an affinity for oxygen; and yet, in acting upon iron or zinc, is said to cause the oxidizement of these metals, not, like nitric acid, at its own expense, but by the decomposition of water, of which the hydrogen is in consequence evolved. Many bodies which do not otherwise react with it, cause its decomposition when aided by the so- lar rays. Of Oxycliloric or Perchloric Acid. 712. Preparation. After the chlorous acid has been liberated from chlorate of potash, the residue consists partially of oxychlorate of potash, as already stated. (700.) This is mingled with bisulphate of potash formed at the same time, but may be separated by repeated solution and crystallization, as the bisulphate is more soluble.*" 713. Oxychloric acid may be obtained from oxychlorate of potash by distillation in a retort with its own weight of sulphuric acid, diluted with a like weight of water at the temperature of 280. It is purified by carefully precipitating the sulphuric acid which comes over with it, by means of ba- rytic water, and redistillation. 714. Properties. Like chloric acid, it is insusceptible of the gaseous form, and, as a liquid, exists only in combination with water, being limpid, colourless, and having a lively acid taste. It reddens, but does not subse- * In evolving oxygen from chlorate of potassa, by means of a porcelain retort and chauffer of coals, it excited surprise, that while the greater part of the gas could be obtained in a glass retort, without softening the glass, there was a portion which required a higher temperature than that which flint glass is capable of enduring. While contemplating some experiments for the explanation of these phenomena, 1 learned that Soubieran had furnished the true explanation of the mystery. He had ascertained that one portion of the salt, receiving two equivalents of oxygen from another, became converted into an oxychlorate, of which the decomposition was more difficult than that of the chlorate. Subsequently this process has been resorted to by my young friend and late pupil, Mr. Boye, and my son, to obtain oxychlorate, for which purpose they have subjected a pound of chlorate of potash, at a time, to partial decomposition. The mass which remains after all the oxygen has been ex- pelled, that can be extricated without softening flint glass, consists of a mixture of chloride of potassium and of oxychlorate of potash. As of all the salts of potassa, that in question is the most sparingly soluble in water at 60, by solution in this liquid while boiling hot, and cooling the solution, the salt precipitates, and may bo purified by repeating this part of the process. 128 INORGANIC CHEMISTRY. quently bleach an infusion of litmus. It is decomposed neither by the so- lar rays, sulphurous acid, nor sulphuretted hydrogen. It dissolves zinc and iron with disengagement of hydrogen. It exercises strong affinities, and is the most enduring of the combinations of chlorine with oxygen ; which is the more surprising, as it is in general true that in proportion as any one ingredient predominates in a compound, it is the more easily separated in part. 715. By the reaction of sulphovinic acid, with oxychlorate of barytes, Mr. Boye and my son have procured an ether, which in its explosive ener- gy, is scarcely equalled by the chloride of nitrogen. It is I believe the only ethereal compound which is per se explosive, or which detonates from a mechanical shock. SECTION III. OF BROMINE. 716. This name has been given to a substance analo- gous to chlorine, from the Greek fyvw, fetidity. 717. Bromine was discovered by Balard in 1826, at the salt works of Montpelier in France, in the mother waters of marine salt, in the state of bromide of sodium or mag- nesium. Since then it has been found in the water of the Dead Sea, and in the greater part of the salt springs of the continent, especially those of Germany. In those of Theo- dorshalle near Kreuznach, a sufficient quantity has been found, to make it profitable to effect its extraction. Com- mon salt, in its natural state, often contains traces of the bromides of sodium or magnesium. 718. Preparation. The mother water of marine, or com- mon salt, is impregnated with chlorine, until it acquires a hyacinth-red tinge. The chlorine combines with the hy- drogen and magnesium of a bromide of magnesium, which exists in that water. The bromine, thus displaced, min- gles with the water, which is to be washed with ether. The resulting ethereal solution of bromine, being treated with potash, a bromide of potassium is produced, which, heated in a retort with diluted sulphuric acid and manga- nese, yields bromine, as chlorine is obtained from a chlo- ride by like treatment. 719. Properties. Bromine is a liquid, but is so volatile, that a single drop is sufficient to fill a flask with its red- dish-brown vapour. The specific gravity of bromine is 2.966, being nearly three times the weight of its bulk of water. It freezes at a temperature of from 7 to 12 below zero. BROMINE. 129 It lias, when frozen, a crystalline and leafy texture, with a lead-gray colour, and a lustre almost metallic. It boils at the temperature nearly of 89, forming a vapour resembling that of nitrous acid, and more than five times as heavy as atmospheric air. It does not conduct electricity. Flame is extinguished in the vapour of bromine, acquiring a green- ish colour previous to its extinction. Bromine is slightly soluble in water. Its solubility is not sensibly augmented by heat. The solution has an orange colour, and emits red fumes. In alcohol it is more soluble, than in water, and in ether still more so than in alcohol. 720. It acts upon vegetable colouring matter and or- ganic products, like chlorine, in general, decomposing them in consequence of its affinity for hydrogen. Bromine forms with starch, a yellow compound. It corrodes the skin, imparting a yellow tinge, which endures till the skin is re- novated. In its habitudes with oxygen, hydrogen, sulphur, and phosphorus, and the metals, it has a great analogy with chlorine, but generally its affinities are not so strong. From its reaction with potassium, an intense and almost explosive combustion is said to ensue. When taken inter- nally, bromine acts as a virulent poison. 721. Bromine is supposed to be one of the active sub- stances in mineral springs, especially in those which con- tain common salt. By means of nitric acid it may be ob- tained in the form of a deep brown precipitate, from the mother waters in which it exists, but there is much lost by its solution, and subsequent volatilization during the eva- poration of the solvent. Experimental Illustration. 722. Bromine exhibited as a liquid; also in the state of vapour. COMPOUNDS OF BROMINE WITH OXYGEN AND CHLORINE. Of Bromic Acid. 723. Bromine forms but one compound with oxygen, called bromic acid, which was discovered by Balard. 7:24. Preparation. When sulphuric acid is added to bromate of baryta dissolved in water, a sulphate of baryta is precipitated, and bromic acid re- mains in solution, which may afterwards be concentrated by evaporation. 725. Properties. Bromic acid, thus obtained, is a liquid of the consist- 17 130 INORGANIC CHEMISTRY. ence of syrup. If we endeavour to remove any farther portion of the wa- ter, the acid is decomposed into oxygen and bromine. Bromic acid first reddens and then whitens litmus paper. It has a strong taste, acid but not caustic. Its odour is hardly perceptible. Sulphurous and phosphorous acid, and all the acids which have hydrogen for their radical, decompose it by removing the oxygen. Concentrated sulphuric acid produces the same effect by removing the water, without which bromic acid cannot exist. 726. Bromic acid is composed of one atom of bromine 78, and five of oxygen 40. Its equivalent is therefore 118. Of Chloride of Bromine. 727. When a current of chlorine is passed through bromine, a liquid compound is produced of a reddish-yellow colour, but not so deep as that of bromine. This liquid is volatile, of an intolerable smell, producing tears ; has an excessively disagreeable taste, and a colour resembling that of eu- chlorine. Water dissolves this chloride, acquiring the power of bleaching litmus. Bases produce with its ingredients, a bromate, a bromide, and a chloride. SECTION IV. OF IODINE. , 728. Iodine has been found in various sea plants, espe- cially the common sponge, also in mineral waters in a va- riety of regions of the earth, remote from each other. It exists also in combination with various fossils. From the experiments of my late friend Dr. Steel, of Saratoga, and others, it appears to be an ingredient in some of the mine- ral waters of that place. 729. Preparation. Iodine is obtained from the lixivium of kelp, from which carbonate of soda is manufactured. After all the soda has been crystallized, the residuum is concentrated, and being heated with sulphuric acid, in a retort, the iodine passes over, and condenses in shining crystals of an intense purple or black colour. 730. Iodine may be precipitated from the mother waters of salts, with which it is naturally associated, by a mixture of eight parts of sulphate of copper, and one of green sul- phate of iron. From this precipitate iodine may be ob- tained by intense ignition, in a retort, with an equal quan- tity of dry peroxide of manganese. 731. Properties. When solid, iodine is of a bluish-black colour, friable, and almost insoluble. It stains the skin yel- low. It fuses at 225 and volatilizes at 350, in a beautiful IODINE. 131 violet vapour. Hence its name, from the Greek ,^ 5 , violet- coloured. Its taste is acrid and hot, and continues for a long time in the mouth. When taken internally, it acts as a poison. It is incombustible either in oxygen, or atmo- spheric air; but forms acids severally with oxygen, chlo- rine, and hydrogen, called iodic, chloriodic and iodohydric* acids. In its habitudes with the Voltaic pile, it is more electro-negative than any other matter, excepting oxygen, sulphur, chlorine, bromine, and probably fluorine. With all the varieties of fecula, starch, sago, arrow root, &c., io- dine produces an intensely blue colour; so that these sub- stances are reciprocally tests for each other. When mois- tened it vaporizes perceptibly, producing an odour similar to that of chlorine, but which yet has a peculiar character. The specific gravity of iodine in the solid state is 4.946. 732. The vapour of iodine is alleged to have the highest specific gravity of any known aeriform fluid, being 8.716, or nearly nine times as heavy as atmospheric air. In con- densing it is peculiarly prone to crystallize, assuming the form of an elongated octoedron, with a rhomboidal base. Water does not dissolve more than TsWth of its weight, acquiring a russet colour, but no taste. When the water has a salt added to it, especially muriate or nitrate of am- monia, it dissolves a larger quantity of iodine. The aque- ous solution does not give out oxygen in the solar rays, nor destroy vegetable colours. Iodine has a great analogy to chlorine and bromine, though more feeble in its affini- ties than either. 733. Soubieran recommends that, in order to apply starch as a test for iodine, the liquid to be essayed should be rendered slightly acid by means of nitric acid. After this addition and that of the starch, it will, in the course of an hour, acquire successively a reddish tint, a brownish- red, a blue, and finally a black colour; or, in other words, the blue by its intensity, becomes equivalent to black. It has been alleged that in this way iodine may be detected in a liquid of which it forms only the 4TFoooth part. 734. Another mode is to include the liquid to be tested in a bottle made air-tight by means of a cork, from which is suspended a piece of moist paper sprinkled with finely * The term hydriodic has hitherto been applied to this acid, but Thenard, as well as myself, calls it iodohydric acid. The considerations which induced me to make this change will be given hereafter. 132 INORGANIC CHEMISTRY. powdered starch. If iodine be present, it will tinge the starch. It is allowed by Baup that iodine may be thus discovered, when existing in a liquid, in a proportion no greater than that of a millionth. 735. Balard recommends that, after boiling the liquid with a small quantity of starch, a solution of chlorine in water be added by means of a tube descending to the bot- tom. The chlorine, at the line of contact, disengages the iodine from its combinations, and enables it to act upon the starch. I resorted to a similar process, about twenty years ago, using sulphuric acid in the manner in which the chlorine is employed by Balard. Experimental Illustrations. 736. A glass sphere containing iodine, on being warm- ed, appears filled with a violet-coloured vapour. 737. To a large glass vessel, containing some boiled starch diffused in water, a small quantity of iodine being added, the fluid becomes intensely blue. Process for the extemporaneous Evolution of Iodine. 738. Heat nearly to the tem- perature of ebullition about two ounces of concentrated sulphuric acid, in a glass globe like that re- presented in this figure. 739, It is preferable to have the whole of the globe heated, with due caution, over a large charcoal fire. Then quickly trans- ferring it to the iron tripod, pre- viously heated, and furnished with a small bed of hot sand, throw into the acid about half a drachm of iodide of potassium, sometimes called hydriodate of potash. Instantaneously the ca- vity of the globe will become re- plete with the splendid violet va- vour of iodine, which will soon after condense, on those portions of the glass which are first re- frigerated, in crystals, symmetri- cally arranged, of great beauty rind unusual si/.e. IODINE. 133 COMPOUNDS OF IODINE WITH OXYGEN. Of lodic Acid. 740. When iodine is subjected to a current of chlorous acid gas, previ- ously dried by passing over chloride of calcium, the gas is absorbed, and a yellow liquid produced. From this, heat expels all the chlorine of the acid, while its oxygen, uniting with the iodine, forms iodic acid. 741. Properties. Iodic acid is an inodorous crystalline solid, much heavier than water, with an acid and astringent taste. It deliquesces in moist air, but remains unaltered when the air is dry. In water it is soluble, but is precipitated from it by alcohol, in which it is insoluble. Its aqueous solution first reddens and then whitens litmus. With a great number of salifiable bases it forms salts, which detonate if mingled and ignited with any dry combustible matter. In common with bromic acid, it is decom- posed by those acids which have hydrogen for their radical, and by many others which have not their highest proportion of oxygen. It contains one atom of iodine, and five of oxygen. Of Hyperiodic and lodous Acid. 742. An acid, containing more oxygen than iodic, has been recently dis- covered by Magnus, to which the name of hyperiodic has been given. But little has been ascertained respecting its properties. Sementini has asserted that he has discovered two additional compounds of oxygen with iodine, one of which he calls oxide of iodine, the other iodous acid. Their exist- ence, however, requires farther confirmation. Of the Chlorides of Iodine. 743. According to Thenard, chlorine forms with iodine a protochloride and a perchloride. The former contains one atom of each ingredient, the latter consists of five atoms of chlorine and one of iodine. The protochlo- ride is the chloriodic acid of Davy. 744. To the perchloride the name of perchloriodic acid may be due. Thenard awards the appellation of acid to neither. Chloriodic acid is ob- tained by subjecting iodine in excess, to the action of chlorine. A liquid is produced of a deep reddish-brown colour, much heavier than water, and having in its mechanical properties a great analogy to bromine. It has an acid taste, and reddens litmus. Water dissolves it without sustaining or causing any decomposition, but abandons it to sulphuric ether. If the abovementioned pi-ocess be so varied as to have an excess of chlorine, per- chloriodic acid is produced, which is a crystalline and volatile substance of a yellowish-white colour, and emitting an effluvium so irritating as to pro- duce tears and a sense of suffocation. Of the Bromides of Iodine. 745. Bromine combines with iodine in two proportions. A protobromide is obtained when iodine is subjected in excess to the action of bromine. It is solid, and when warmed affords reddish-brown vapours, which condense into crystals of the same tinge, in shape resembling fern leaves. By the same .process, when the proportions are reversed, a perbromide results, 134 INORGANIC CHEMISTRY. which is liquid. Both of these bromides are soluble in water, and bleach without reddening litmus. Subjected to the action of the Voltaic pile, bro- mine goes to the positive, iodine to the negative pole. SECTION V. OF FLUORINE. 746. In the last edition of this Compendium it was stated, that an ele- mentary body bearing the name at the head of this section, was inferred to exist by many chemists ; and that I had no doubt as to the existence of flu- orine. Since that statement was written, Baudrimont has succeeded in ob- taining this interesting and energetic element, by passing fluoride of boron over red-hot minium, or preferably by heating a mixture of intimately min- gled chloride of calcium and black oxide of manganese, with concentrated sulphuric acid. It is to be regretted that this process does not evolve fluo- rine in a state of purity, in consequence of the simultaneous evolution of the fluohydric and fluosilicic acids in a small proportion. 747. Properties. Fluorine is described as a gas of a yellowish-brown colour, with an odour like that of chlorine mingled with a smell of burnt sugar. It combines directly with gold but not with glass. The observa- tions which have been made upon it, so far as they extend, justify the in- ferences respecting its properties, to which previous knowledge and reason- ing had given rise ; and go to confirm its pretensions to a place among the halogen bodies of the basacigen class. (627, &c.) (633, &c.) 748. As there are no known compounds of fluorine with any of the ele- ments comprised in the class to which it belongs, consistently with the ar- , rangement to which I have declared my intention to adhere, no further consideration can be given to it, until the bodies are treated of with which its most important combinations are formed. SECTION VI. OF SULPHUR. 749. Sulphur is a mineral production, well known in com- merce under the name of brimstone. It is sold both in rolls and in flowers. It is found pure in the vicinity of volcanoes, of which it is a product. In combination with metals it is widely disseminated. From some of its me- tallic sulphides, which are known under the name of sul- phurets, or pyrites, it may be obtained in the pulverulent form, to which the name of flowers has been given, by sublimation. SULPHUR. 135 750. Properties. Sulphur is yellow, inodorous, and in- sipid, becomes electric by friction, and is liable by the warmth of the hand to be fractured with a slight noise. It evaporates and burns with a feeble flame at 180, and melts at 225, and by pouring out the liquid portion, after the mass is partially congealed, it may be obtained in crystals. In close vessels at the temperature of 600 it vaporizes, or sublimes, and afterwards condenses in the well known form of flowers as above stated. The flowers are by the microscope ascertained to be crystalline, and are generally contaminated by a minute portion of sulphu- rous acid, which may be removed by repeated washing. 751. All the metals, when presented, in thin leaves or powder, to the vapour of sulphur without access of air, enter into combustion with it, forming compounds which have been designated as sulphurets; but which, as I have stated, ought to be called sulphides. (686-7.) Combustion also ensues when the metals in a divided state are heated with sulphur. The sulphides, formed with the metals of the earths and alkalies, are soluble in water. From the resulting solution the sulphur is thrown down by acids. Like phosphorus, sulphur is susceptible of a slow as well as quick combustion. In consequence of the low tempera- ture at which it is capable of becoming converted by com- bustion into sulphurous acid, sulphur may be burned out of gunpowder without causing it to flash. If raised to the temperature of 369, it enters into a more active reaction. The products of the combustion of sulphur are sulphurous acid, mingled with a small portion of anhydrous sulphuric acid. The hue of the flame when the combustion is slow is blue; in oxygen its flame is of a splendid purple. Ber- zelius alleges that when sulphur is rubbed on any body, a brick for instance, which has been previously warmed, though not sufficiently to inflame the sulphur, an extremely feeble blue flame is produced with a peculiar odour. This flame he conceives to be the effect of the evaporation, un- accompanied by any combustion; "since a cold body held above it is covered with the flowers of sulphur unchanged." This reason, however, appears insufficient; since the su- blimation of one portion of the sulphur does not demon- strate that another is not oxydized, any more than the de- position of carbon upon a cold body exposed to a smoky flame, proves that another portion of carbon, arising from 136 INORGANIC CHEMISTRY. the same source, cannot at the same time be converted into carbonic acid, as is known to be the fact. 752. Some very curious anomalies have been observed respecting the phenomena of sulphur when kept over the fire after fusion, which the limits prescribed to this work will not allow me to introduce.* Experimental Illustrations. 753. Sulphur exhibited in flowers and in rolls; also crys- tallized as abovementioned. 754. Combustion of Dutch gold leaf and of an iron bar by sulphur. Iron wire converted into a sulphide by the vapour of sulphur emitted in a jet from the touch-hole of a gun barrel, made red-hot in the, vicinity of the aperture. The Combustion of Iron by a Jet of Vaporized Sulphur. 755. If a gun-barrel be heated red-hot at the but-end, and a piece of sul- phur be thrown into it, on closing the muzzle with a cork, or blowing into it, an ignited jet of vaporized sulphur will proceed from the touch-hole. Exposed to this, a bunch of iron wire will burn as if ignited in oxygen gas, and will fall down in the form of fused globules, in the state of protosul- phide. Hydrate of potash, exposed to the jet, fuses into a sulphide of a fine red colour. 756. In order to designate the different proportions of oxygen existing in any oxide, relatively to the other ingredient, I employ the following no- menclature in obedience to the authority of Thenard and others. Oxydized body. Oxygen. Appellation. 1 atom 1 atom protoxide. 2 atoms 1 atom dioxide or suboxide. 1 atom 2 atoms fooxide or deutoxide. Uerzclius, Vol. I. p. 250. SULPHUR. 137 1 atom 3 atoms trioxide. 1 atom 4 atoms g-wadroxide. Either 2 atoms 3 atoms ) -j ., , sesamoxiae. or 1 atom If $ 757. The monosyllables di, bi> tri, qua, have an analogous influence upon the meaning, when used before any other of the words employed as above, to distinguish the compounds severally formed by the basacigen ele- ments, (633,) hence we have cZichloride, proZochloride, bichloride, trichlo- ride, ^warfrichloride, &c. It will be perceived that as in the terms qua- droxide and ^wadrichloride, the monosyllable qua, has such letters added as may render the resulting epithet easy to pronounce, and agreeable to the ear. 758. The second stage of combination in which the proportion of the electro-negative ingredient exceeds the ratio of equality, has been distin- guished by prefixing the word deuto. Hence deutoxide, deutochloride, deutobromide, deutiodide. I prefer ftzoxide, as more precise and descrip- tive where the presence of two atoms is to be indicated. Per is prefixed to signify the presence of oxygen in a maximum degree, and in the case of iron, is used to designate a ses^moxide, in that of mercury a fooxide. But this monosyllable is also prefixed to compounds containing any number of atoms, whether forming a base or an acid. Hence, we have an acid dis- tinguished by the appellation perchloric, which contains seven atoms of oxygen. The syllables in question are prefixed by the French chemists to the words chlorure, bromure, iodure, fluorure, cyanure, as they are by the British chemists, prefixed to the modifications of those names which they employ. COMPOUNDS OF SULPHUR WITH OXYGEN. f With two atoms of oxygen, forms sulphurous acid, equi- One atom of .' valent - - 32 sulphur, 16, j With three atoms of oxygen, forms sulphuric acid, equi- L valent - 40 f With two atoms of oxygen, form hyposulphurous acid, Two atoms of! equivalent - 48 sulphur, 32, ] With five atoms of oxygen, forms hyposutphuric acid, L equivalent x - - 72 Of Hyposulphurous Acid. 759. This acid exists only in combination with salifiable bases, and of the salts formed I believe no useful application has been made. Any at- tempt to explain the method in which hyposulphites are produced, will be deferred until I reach the subject of the compounds formed by acids with metallic oxides. Of Sulphurous Acid. 760. Preparation. It is formed by the ordinary combustion of sulphur, or by boiling sulphuric acid on sulphur, on mercury, or on any other sub- stance by which it may be partially deoxidized. 761. Properties. Sulphurous acid is a colourless gas, possessing the well known odour of burning sulphur. It is incapable of supporting com- bustion, and is deleterious to life, a spasmodic closure of the glottis follow- ing any attempt to respire it. 762. It first reddens and then bleaches litmus, and destroys organic IS 138 INORGANIC CHEMISTRY. colours generally. It is used on this account to bleach silk and wool. Sul- phurous acid is soluble in water, which absorbs 43 times its bulk. When a solution of this gas is exposed to the air, it absorbs oxygen, and is con- verted into sulphuric acid. This acid, with four times its bulk of water, forms a crystalline hydrate, which melts under 40 j disengaging the greater part of the acid. After being rendered anhydrous by passing over chloride of calcium, sulphurous acid gas, by exposure to a temperature of 12, condenses into a colourless, transparent liquid, having the specific gravity of 1.45. When dropped in vacuo on the bulb of a spirit ther- mometer, previously, at 50, and surrounded with cotton, the intense cold of 90 will be indicated. It is even said that alcohol has been frozen in this manner. Sulphurous acid gas is decomposed at a red heat, either by hydrogen or carbon. It is displaced from its combinations, by all the acids except cyanhydric (prussic) and carbonic acid. Impregnation of Water with SulpMrous Acid, by means of an appropriate Apparatus. 763. Into the open neck of a tall receiver, a recurved pipe is fastened, so as to descend a few inches below the neck. The other end of the pipe terminates in a brass socket, into which is inserted the stem of an inverted glass funnel. The receiver is placed over the shelf of the pneumatic cistern, covered about an inch deep with water, and includes a stand supporting a tumbler of the same liquid. A pipe, extending from a suction pump, rises within the receiver, nearly as high as the stand. If, under these circumstances, the pump be put into action, the con- sequent exhaustion of the air from the receiver causes a rise into it of the water from the cis- tern, until the resistance which this water opposes to a further elevation is greater than that opposed by the water in the tumbler, to the entrance of air from the recurved pipe communicating with the funnel. The air of the funnel will then be drawn into the receiver through the liquid in the tumbler; and if sulphur, carbon, phosphorus, a candle, lamp, or any inflammable gas be placed, while burning, under the funnel, the fumes may be made to pass through the water, which may be coloured by litmus, or may contain lime, ammonia, baryta, or any other desirable agent, which it may be capable of dissolving or suspending. Of HyposulpJiuric Acid. 764. This acid is obtained by passing sulphurous acid gas through peroxide of manganese suspended in water in a finely divided state. If the mass be kept cold, the peroxide is reduced to the state of protoxide, while the oxygen forms with the sulphurous acid, hyposulphuric acid. This, with the protoxide, produces a salt, which, remaining dissolved, may be purified by crystallization. By the addition of sulphide of barium to a solution of the resulting crystals, the manganense is precipitated in the state of a sulphide, and hypo-sulphate of baryta is obtained. From this salt the hyposulphuric acid may be separated by sulphuric acid, and concen- trated by evaporation in vacuo, till it acquires the specific gravity of 1.347. SULPHUR. 139 By heat or farther concentration, -it is decomposed into sulphurous and sulphuric acid. 765. Hyposulphuric acid is a colourless, inodorous liquid, which reddens litmus, has an acid taste, and dissolves zinc with disengagement of hydrogen. Of Sulphuric Acid. 766. Sulphuric acid has been known since the close of the fifteenth century, when it was obtained by Basil Va- lentine by the distillation of green vitriol, or sulphate of iron. 767. Preparation. This acid may be obtained by burn- ing sulphur and nitre in chambers lined with lead, or by the process abovementioned, by which it was originally obtained; whence the almost obsolete name, oil of vitriol. It is best purified by distillation. 768. I shall defer for the present the illustration of the process for procuring sulphuric acid by sulphur and nitre ; also any exemplification of its habitudes with other bodies. 769. Properties. It is a liquid, oleaginous in its con- sistency, caustic when concentrated, intensely acid when dilute. When three parts are added to one of water, a boiling heat is produced. (350.) Hot water explodes with it as with a melted metal. It is diluted by the absorption of moisture when exposed to the air. No acid equals it in the power of reddening litmus. When pure it is colour- less and has but little smell. Of the Sulphuric Acid of Nordhausen, and of Anhydrous Sulphuric Acid. 770. The sulphuric acid of Nordhausen differs from that in use in this country, in containing a portion of acid, which being free from water, is called anhydrous. This anhydrous portion being volatile, assumes the form of vapour, and, meeting with the moisture of the air, condenses into white fume's. (817.) 771. The fuming acid of Nordhausen is obtained by calcination and dis- tillation from sulphate of iron, (known also by the name of green vitriol) contained in retorts of stone-ware. It may be obtained also from white vitriol or sulphate of zinc by similar treatment. The anhydrous acid may be separated from the other portion by gentle distillation, with the aid of a refrigerated receiver, previously well desiccated. It is a crystalline body resembling asbestos, and may be rubbed between the fingers like wax, without their being attacked. In the air it emits thick fumes having an acid smell. At a temperature above 64 it is liquid. Once congealed it cannot be fused without great care; as the temperature at which it is va- porized, is but little above that at which it liquefies. Hence it is apt to undergo a sudden^enlargement of bulk which causes it to be thrown out of the containing vessel. When vaporized it forms a colourless gas. Neither 140 INORGANIC CHEMISTRY. in this state nor in its crystalline form has it any effect on litmus paper rendered perfectly dry. When passed through a red-hot tube of porcelain, it is resolved into oxygen and sulphurous acid. 772. Either caustic lime or baryta enters into a species of combustion with this gas, forming with it a sulphate. 773. The solid anhydrous acid, thrown into water, produces a commo- tion resembling the effect of a hot iron, and, when mingled with an equiva- lent proportion of water, explodes with a force sufficient to fracture a glass vessel. 774. The fuming acid of Nordhausen is of use for the solution of indigo employed in dyeing ; as the anhydrous acid answers better for this purpose than the aqueous. 775. It combines chemically in four proportions with water. The com- pound containing water in the least proportion is formed in some of the processes for producing the acid of Nordhausen. It is a crystalline body, which probably consists of 2 atoms of anhydrous acid and 1 of water. Four parts of the anhydrous acid and about 1 of water form the concen- trated acid of the shops, of the specific gravity of 1.85, which is considered to contain 1 atom of water to 1 of acid. When the acid is to the water as 4 to 2, a compound results, of which the density is greater than the mean density of the constituents, and which probably consists of 2 atoms of water to 1 of acid. A similar alteration of the density follows the addition of water until the specific gravity is reduced to 1.632. Of the Chlorides of Sulphur. 776. According to Thenard, there are two chlorides which are both liquids. One contains 2 atoms of sulphur to 1 of chlorine ; the other an atom of each ingredient. The protochloride is a yellow, viscid, oleaginous liquid, heavier than water, and which boils at 280. The other is reddish- brown, volatile, fuming and acrid, and boils at 147. Both are decom- posed by water, and alcohol. Of the Bromide and Iodide of Sulphur. 777. The flowers of sulphur dissolve in bromine, producing a reddish, oleaginous, fuming liquid. When iodine is heated gently with sulphur, it forms a brilliant crystalline iodide, of a steel-gray colour. -t SECTION VII. OF SELENIUM. 778. In 1817, Berzelius, examining, in concert with Gahn, the old method of preparing sulphuric acid, as practised at Gripsholm, in Sweden, discovered a sediment in the acid, partly red, partly brown, which, treated by the blowpipe, produced the odour of a rotten radish, and left a minute portion of lead. The odour thus evolved had been considered by Klaproth as an indication of tellurium. In consequence, Berzelius took care to col- lect all the deposition, produced in the manufacture of sulphuric acid dur- ing some months ; no other sulphur than that of Fahlun being employed. SELENIUM. 141 The discovery of a new substance resulted, to which he gave the name of selenium, from the Greek word a-g AW, the moon, suggested by its analogy with tellurium, named from tellus, the earth. 779. Selenium seems much distributed throughout nature. In Sweden it has been found combined sometimes with copper and silver, sometimes with copper only. A small quantity has been detected in cubic galena. In Norway it has been discovered united with tellurium and bismuth ; in the Hartz, combined with lead, copper, and mercury. Stromeyer has found it in a mineral from the Lipari islands, combined with sulphur. 780. Preparation. From the deposition in which it exists, as above stated, selenium is extricated by solution in aqua regia, precipitation by sulphuretted hydrogen, re-solution in the same solvent, precipitation by pot- ash, filtration and evaporation of the residual liquid, desiccation of the re- sulting mass, and sublimation with the addition of sal ammoniac. Selenic acid, produced by the reaction of the selenium with oxygen in the aqua regia, is saturated by the potash, and afterwards deoxidized by the hydro- gen of the ammonia in the sal ammoniac employed, the selenium being sublimed by the heat. 781. Properties. Selenium, on cooling after distillation, assumes a shining surface of a deep reddish-brown colour, with a metallic brilliancy resembling that of the blood-stone (hsernatite). Its fracture is conchoidal, vitreous, of a lead-gray, with metallic lustre. Very slowly refrigerated after fusion, its surface becomes granulated and uneven, of a reddish-gray, and devoid of lustre. By quick refrigeration the characters above indicated result. Selenium has little tendency to crystallize, yet it is capable of sepa- rating in a crystalline pellicle, or of forming a crystalline vegetation, upon the sides of the vessel, from its solution in the state of a selenhydrate. When precipitated cold from a diluted solution, whether by zinc or sulphu- retted hydrogen, it is red like cinnabar. But if this precipitate be boiled, it turns black and consolidates, becoming heavier. When pulverized, se- lenium becomes of a deep red, and likewise when in very thin layers. With heat it softens, and at the boiling point of water, acquires a semifluid- ity, becoming completely fluid at a temperature somewhat higher. In cooling it remains soft for a long time, and may, like heated sealing-wax, be drawn out into filaments. These, by reflected light, are gray, with some metallic brilliancy, but, by transmitted light, are transparent, and of a ruby- red colour. 782. When selenium is heated nearly to redness in a distillatory appa- ratus, it assumes, with ebullition, the form of a vapour of a yellow colour, deeper than the hue of chlorine, yet lighter than that of sulphur. This vapour condenses in the neck of a retort in black drops, which coalesce like those which are formed by the condensation of mercury. When condensed with access of air, selenium appears like a red fume, and is deposited in a state analogous to the flowers of sulphur, but of a cinnabar-red colour. The smell of a radish is only perceived when the heat is sufficient to be productive of oxidation. The specific gravity of selenium is from 4.3, to 4.32. Compounds of Selenium with Oxygen. 73. Selenium has but a feeble affinity for oxygen, yet forms a volatile oxide, which has the smell either of radish or decayed radish. It forms also two acids, the selenious and selenic. The latter of these is isomor- phous with sulphuric acid. (474.) 142 INORGANIC CHEMISTRY. 784. Selenious acid is procured by the combustion of selenium in oxy- gen gas, or by reaction with nitric, or nitromuriatic acid. 785. Selenic acid is obtained by the deflagration of nitre with selenium in a hot crucible; a seleniate of potash results, which is decomposed by nitrate of lead, and the resulting seleniate of lead is decomposed by sul- phuretted hydrogen. The sulphuret of lead precipitates, while selenic acid is dissolved in the water employed. When heated to 280 degrees, it attains its highest concentration, and at 290 degrees is decomposed into oxygen and selenious acid. 786. The highest specific gravity of selenic acid is 2.6. It resembles sulphuric acid in its consistency, in its evolving heat by dilution with water, and in the power of dissolving iron and zinc, with the evolution of hydro- gen. It cannot be rendered anhydrous. When its density is at the maxi- mum, it contains 16 per cent, of water. With the aid of heat, it oxidizes and dissolves copper and even gold, but not platinum. With chlorohydric acid, it constitutes a sort of aqua regia, which dissolves both gold and pla- tinum. Its salts cannot be distinguished from the sulphates, unless by the property of detonating with carbon at a red heat, and that of causing an evolution of chlorine, when boiled with muriatic acid. Selenic acid may be separated from sulphuric acid by saturation with potash, and ignition with sal ammoniac. The selenic acid is decomposed into selenium by the hydrogen of the ammonia. 787. Selenium combines with chlorine and bromine, and with sulphur in every proportion. 788. As there is not one of the metals which have decided pretensions to the metallic character, which is not an excellent conductor of both heat and electricity, and as metallic brilliancy is another striking attribute of the metallic genus, I cannot understand wherefore selenium, which is admitted to be destitute of the two first mentioned characteristics, and to possess the last imperfectly, should be received into the class of metals ; while carbon, which in the form of plumbago, is endowed with them all, is excluded. I can not 'consider selenium as a metal. It is stated to have the brilliancy of haematite, which is, I conceive, inferior in that respect to plumbago, which Berzelius considers as pure carbon. SECTION VIII. OF TELLURIUM. 789. A metal has been found in the veins of auriferous silver in the mines of Transylvania, which has been called tellurium. It is found also in small quantities in Norway, united to selenium. Tellurium has likewise been discovered in Connecticut. It is found chiefly in the state of an alloy with gold and silver. 790. Tellurium displays a metallic brilliancy, and is of a colour between that of tin and antimony, and of a lamellated structure. W T hen melted in a glass vessel, replete with hydrogen, and slowly cooled, it assumes the ap- pearance of burnished silver. Fused in a vessel, it presents crystals of a determinable form. It fuses below a red-heat, and above that temperature is volatilized. When heated before the blowpipe, it takes fire, and burns with a blue flame bordering on green, and is dissipated in gray pungent HYDROGEN. 143 fumes, which have sometimes the smell of horse-radish. This smell is as- cribed by Berzelius to the presence of selenium. Latterly the same author assumes its specific gravity to be 6.2324. 791. Tellurium may be oxidized cither by combustion or by nitric acid. The oxide, exposed before the blowpipe upon charcoal, is decomposed with explosive violence. 792. Berzelius alleges that tellurium will dissolve in concentrated sul- phuric acid without being oxidized, in which it differs from other metals. I infer that it forms a soluble oxysulphide. The colour of the resulting solution is purplish-red. Tellurium is more especially entitled to our no- tice on account of its great analogy to sulphur and selenium, and of its forming both acids and bases, which uniting, form telluri-salts. It is upon this ground that Berzelius included it in his amphigen class, and that I con- sequently place it among the basacigen bodies. * OF RADICALS. 793. Radicals are bodies capable of forming with a ba- sacigen body either an acid or a base, and are divided into those which are metallic, and those which are non-metallic. (633.) OF NON-METALLIC RADICALS. The bodies which I place under this head are: Hydrogen, Boron, Nitrogen, Silicon, Phosphorus, Zirconion. Carbon, SECTION I. OF HYDROGEN. 794. In its gaseous state, it is the principal constituent of all ordinary flame. It is an ingredient in water, and combined with oxygen and carbon, it is found in all ve- getable and animal substances. It derives its name from vfy, water, and y/va^i, to produce. 795. Preparation. Per se, hydrogen exists only in the gaseous state. In this form it may be obtained by the re- action of diluted sulphuric or muriatic acid with zinc or iron, or of steam with iron turnings, made red-hot in a gun barrel. It may be evolved in a state of purity, and con- 144 - INORGANIC CHEMISTRY. sequently destitute of odour, from pure water, by Voltaic agency, or by reaction with an amalgam of potassium. Self -regulating Reservoir for Hydrogen and other Gases. 796. The following figure represents a self-regulating reservoir for hy- drogen gas. 797. This very perspicuous engraving can require but lit- tle explanation. Suppose the glass jar without to contain di- luted sulphuric acid; the in- verted bell, within the jar, to contain some zinc, supported on a tray of copper, suspended by wires of the same metal from the neck of the bell. The cock being open when the bell is lowered into the position in which it is represented, the at- mospheric air will escape, and the acid, entering the cavity of the bell, will, by its reaction with the zinc, cause hydrogen gas to be copiously evolved. As soon as the cock is closed, the hydrogen expels the acid from the cavity of the bell; and, consequently, its reaction with the zinc is prevented, until another por- tion of the gas be withdrawn. As soon as this is done, the acid re-enters the cavity of the bell, and the evolution of hydrogen is renewed and con- tinued, until again arrested, as in the first instance, by preventing the escape of the gas, and consequently causing it to displace the acid from the inte- rior of the bell, within which the zinc is suspended.* 798. By means of apparatus of this kind, I have been enabled to have self-regulating reservoirs of nitric oxide, of sulphydric acid, of carbonic acid, of chlorine, and of chlorohydric acid, merely by changing the ma- terials, and making such a modification of the means of supporting them as the agents employed or evolved require. * The principle of this apparatus is analogous to that which was contrived by Gay-Lussac. I had employed the same principle, however, when at Williamsburg, to moderate the evolution of carbonic acid, before I had read of Gay-Lussac's appa- ratus. I prefer the modification above described. In the first place, it is internally more easy of access for the purpose of cleansing ; secondly, it is much better quali- fied for containing sulphuret of iron, or marble, for generating sulphuretted hydro- gen, or carbonic acid gas: and thirdly, by raising the bell glass, until the liquid within and without is on a level, the pressure may be removed. In the other form, the pressure on the gas is so great, that, unless the tube, the cock, and the junctures be perfectly tight, there must be a considerable loss of mate- rials ; since the escape of gas inevitably causes their consumption, by permitting the acid to reach the zinc, or other material employed. HYDROGEN. 145 Large Self-regulating Reservoir for Hydrogen. V 799. This figure represents a self-regulating reservoir for hy- drogen, constructed like that de- scribed in the preceding article; excepting that it is about fifty times larger, and is made of lead, instead of glass. This reservoir may be used in all experiments requiring a copious supply of hydrogen. When gas is to be supplied to the hydro-oxygen, or compound blowpipe, the perfo- rated knob at the end of the pipe, which has an orifice on one side, is placed under the gallows, G, (seen in the fig. of the compound blowpipe, 331) and fastened air- tight to the pipe of that instru- ment, by the pressure of the screw of the gallows. The gas is retained, or allowed to flow through the pipe, by means of the valve cock, V, which is much less liable to leak, than one of the common form. 800. Properties of Hydrogen. It is the lightest of all ponderable substances. One hundred cubic inches weigh only 2.13 grains. Its weight to that of oxygen is as 1 to 16. Its specific gravity, the gravity of air being assumed as 1, is 0.0689. It is about 200,000 times lighter than mercury, and 300,000 times lighter than platinum. In its ordinary state it smells unpleasantly. When pure it is without odour. In its nascent state, as when liberated by means of an acid, it is extremely prone to take up a minute portion of sulphur, phosphorus, arsenic, or of some other metals. Of the last mentioned property, a most use- ful application is now made, which I shall mention when treating of the process for detecting arsenic. 801. The respiration of hydrogen, mixed with the same proportion of oxygen as exists in atmospheric air, is not attended by any oppressive sensations; yet a profound sleep is said to have been induced in animals surrounded 19 146 INORGANIC CHEMISTRY. by such a mixture. When breathed either in this way or unmixed, it will be found to produce a ludicrous alteration in a man's voice, making it shrill and puerile, and so out of character as not to be recognised. Sound is said to move in this gas with a velocity three times as great as in the atmosphere. According to the experiments of Leslie, the sound of a clock bell was as feeble in hydrogen as in air rarefied one hundred times. By no degree of pressure which has been tried, can hydrogen be condensed into a liquid. In consequence of its levity, it escapes rapidly from an open vessel, unless inverted. It is pre- eminently inflammable, yet a taper when immersed in it is extinguished. A jet of it, ignited, appears like a feebly luminous candle flame, and, if surrounded by a glass tube, produces a remarkable sound. 802. It has been stated that for equal volumes, all gases have the same capacity for heat; it follows, that for equal weights, the capacities must be inversely as their specific gravities or their densities. Hence hydrogen having the lowest specific gravity, will have the highest specific heat. (257.) It is in fact calculated to be as to that of an equal weight of air as 13.08 is to 1, and to that of an equal weight of water as 3.88 to 1. Its refracting power is ten and a half times greater than that of the atmosphere. 803. When mixed with oxygen or atmospheric air, and subjected to flame, an electric spark, or a wire ignited by galvanism, it explodes. With chlorine it explodes under like circumstances, and likewise in the solar rays. In burning, it disengages sufficient heat to melt 315 times its weight of ice. Dobereiner discovered that platinum sponge, a cold metallic congeries, becomes ignited on en- tering a mixture of hydrogen with oxygen gas, and causes it to inflame by an agency which has not been satisfacto- rily elucidated. It has since been discovered that palla- dium, rhodium, and iridium possess this property in nearly the same degree. I have ascertained that if asbestos, charcoal, or clay be soaked in chloride of platinum, and afterwards desiccated and heated red-hot, the property of inflaming a mixture of hydrogen and oxygen is acquired. Experimental Illustrations of the Properties of Hydrogen. 804. Levity of the gas demonstrated by the ascension of a balloon, or by the effect of filling with hydrogen, a HYDROGEN. 147 glass globe balanced upon a scale beam. (71, &c.) Effect upon the voice shown. Inflammation of a gaseous mix- ture of hydrogen with atmospheric air by platinated asbes- tos, or platinum sponge. Apparatus for lighting a candle by a jet of hydrogen from a self-regulating reservoir, either by the electric spark or platinum. (327.) A mixture of hydrogen and oxygen, ignited within a small cannon, ex- plodes. Candle extinguished and re-lighted by Hydrogen. 805. If a lighted candle be introduced into a wide- mouthed inverted phial, filled with hydrogen gas, the flame of the candle will be extinguished from the want of oxygen. Meanwhile, at the mouth of the bottle, where there is a sufficient access of air, the gas will have taken fire, and will burn with a lambent flame scarcely visible in daylight. Hence if the candle be slowly withdrawn, it will be re-lighted as it passes through the flame. Philosophical Candle. 806. Small pieces of zinc or iron, being introduced into a glass flask, so as to occu- py about one-eighth of its capacity, pro- vide a suitable cork, so perforated as to receive a glass tube terminating in an ori- fice just large enough to admit a common brass pin. ,Pour upon the zinc five parts of water, and adding one of sulphuric acid, fasten the cork, with its tube in- serted, into the mouth of the flask. After all the atmospheric air has escaped from the vessel, on applying the flame of a can- dle to the orifice of the tube, it will be sur- mounted by an inflamed jet of hydrogen, which has been called the philosophical candle. 807. The light given out by the flame of pure hydrogen, is, nevertheless, wholly in- competent to answer the purpose of candle light; but I have ascertained, that the addi- tion of a small quantity of spirit of turpen- tine to the materials obviates this defect. 148 INORGANIC CHEMISTRY. Application of Hydrogen and Oxygen in Eudiometry. 808. The explosive union of hydrogen with oxygen has been much resorted to in the analysis of gaseous mixtures containing either. For this purpose a stout tube, sealed at one end, at the other shaped like a trumpet, has holes drilled into it, near the sealed end, for the introduction of metallic wires, the ends of which approach near enough to each other within the tube, for the passage of an electric spark. A known volume of the explosive mixture being introduced into the tube, and ignited by a spark from an electrophorus or an electrical machine, and the residual air being transferred to a graduated tube, the deficit caused by the process is ascertained. 809. The glass tube, employed in this experiment, with its appurtenances, is called a eudiometer. This appellation was at first applied to the instruments used in the analy- sis of atmospheric air, of which one-fifth part is oxygen gas ; but it has since been applied to all instruments, em- ployed in measuring the results of pneumato-chemical analysis. I subjoin an engraving descriptive of the eudio- meter of the celebrated Volta. Volta's'^Eudiometer. 810. The eudiometer represented by this figure, (see next page) was contrived by Volta, for the analysis of gaseous mixtures and compounds containing oxygen or hydrogen. 811. The body of this instrument, A, is a cylinder of glass, which is cemented below into a brass socket, united by a screw with the cock, B. This cock screws into a hollow brass pedestal, C, with the cavity in which the bore of the cock communi- cates. The glass cylinder is also cemented into a cap, D, which is surmounted by a cock, E, supporting the basin, F. The cavity of the basin communicates, through the bore of the cock when open, with that of the cylinder. Into the perforation in the bottom of the basin, the sealed tube, G, graduated into 200 parts, fastens by a screw cut upon a socket, into which the tube is cemented. On one side of the cy- linder, there is a metallic scale, h, each division of which indicates a section of the bore of the cylinder equivalent to ten degrees on the tube. I, is an insulated wire for passing the electric spark through any explosive mixture which may be intro- duced into the cylinder. A;, is a measure which holds as much gas as, when admit- ted into the cylinder, would be equal to ten divisions of the metallic scale, or to 100 degrees, if allowed to rise into the tube. This measure is furnished with a slide, in which a hole is represented at I. The measure is open when this hole is within it; it is closed when the hole is outside, as it appears in the engraving. By this mechanism it is rendered certain that, with care, the volume of air, taken at one time, will be equal to that taken at another. 812. In order to put this eudiometer into operation, open both the cocks, and depress it in the water of the cistern, until the water rises into the cylinder just above the lower cock. This cock is then to be closed, and the pedestal placed on the shelf of the cistern. Water is to be poured into the basin, until both the basin and cy- linder are full. The glass tube, G, is then to be filled with water and inverted: and the orifice, meanwhile closed with the finger, is to be depressed below the sur- face of the water in the basin, without admitting air. The tube is then screwed into its place, so as to occupy the position in which it appears in the figure. 813. The upper cock being closed, let the measure, k, be plunged in the water of the Volumescope. (Page 149.) HYDROGEN. 149 cistern, the orifice open for the air to escape. Then invert it, the orifice being kept under the surface of the water. Next fill it with the mixture to be analyzed, as for instance a mix- ture of equal volumes of hydrogen and atmos- pheric air. Shut the orifice by moving the slide, allow any excess of air to escape, and then, placing the orifice of the measure under the pedestal of the eudiometer, open the orifice : the gaseous mixture will mount into the cavity of the cylinder. Shut the lower cock, and pass an elec- tric spark through the included mixture. An explosion will ensue, and consequently a portion of the mixture will be condensed into water. By opening the cock, B, the deficit, thus produced, will be compensated by the entrance of an equi- valent bulk of water. Open the upper cock, and allow the residual gas to mount into the gra- duated tube. Detach this tube from the eudio- meter, and closing the orifice with the finger under water, before lifting it from the basin, sink it in water, until this liquid be as high without as within the tube. It may now be seen how far the residual air falls short of the 100 measures introduced. 814. It must be evident that we might operate on double the quantity of gas, by taking the mea- sure full of it twice instead of once; and that a mixture of two volumes of air and one volume of hydrogen might be analyzed, by taking three measures equivalent to 300 parts. The loss by the explosion would be the number of degrees that the residue would fall short of 300, when in the graduated tube. 815. A mixture of three volumes of hydrogen with one of impure oxygen might be analyzed by taking the measure twice full, which is the same as 200 parts. In this case, one-third of the deficit would be the quantity of pure oxygen in of 200, or 50 parts, of the impure gas. 816. The metallic scale accompanying the cylin- der I have never used. Since one of its divisions is equivalent to ten of those on the tube, observa- tions made by means of the latter must be ten times more accurate. 817. Instead of resorting to an electric spark to produce the inflammation of the gases, I have added to this eudiometer a galvano-ignition apparatus, (335,) by means of which a gaseous mixture may at any time be ignited with certainty. Of the Volumescope. 818. In experiments performed with such eudiometers as are mentioned above, the steps of the process cannot be made evident to a numerous class, so as to ena- ble them to judge of the result by inspection. In order to attain this object, I have contrived the apparatus represented on the opposite page, which I have called a volumescope, as I find it very inconvenient not to have a name for every variety of apparatus. It consists of a very stout glass tube, of 30 inches in height, and taper- ing in diameter inside from 2 and th to 1 and th inches. The least thickness of the glass is at the lower end, and is there about fths of an inch. There is an obvious increase in thickness towards the top, within the space of about C inches. The tube is situated between the iron rods, I I, which are riveted, at their lower ends, to a circular plate of the same metal, let into the lower surface of a square piece of plank, P. This piece of plank supports the tube, so as to be concentric with an aperture corresponding with the bore of the tube, and constituting effectively its lower ori- fice. The upper orifice of the tube is closed by a stout block of mahogany, which receives a disk of gum elastic in a corresponding hollow, made by means of a lathe, so as to be of the same diameter as the end of the tube. Into a perforation in the 150 INORGANIC CHEMISTRY. centre of the mahogany block, communicating with 'the bore of the tube, a cock, c, furnished with a gallows screw, is inserted. Through the block, on each side of the perforation, wires are introduced, so as to be air-tight. To the outer ends of these wires two gallows screws, g g, are soldered ; 'to the inner ends a platinum wire, so as to form a galvano-ignition apparatus. (335.) 819. The apparatus being thus constructed, le,t it be firmly fixed over the pneumatic cistern, so that the water may rise about an inch above the lower extremity of the tube. To the gallows screws, g g, attach two leaden rods, severally proceeding from the poles of a calorimotor. By means of a leaden pipe, produce a communi- cation between the bore of the cock and an air pump, so that by pumping the air from the cavity of the tube, the water of the cistern may be made to rise into the space thus exhausted of air. On each side of the tube, and between it and each iron rod, there are two strips of wood S S, scored so as to graduate about seven inches of the tube into eight parts. The various distances between these gradua- tions were ascertained by introducing into the tube, previously filled with water, exactly the same bulk of air eight times, and marking the height of the water after each addition. By these means the instrument is graduated into eight parts of equal capacity ; and we are by aid of it enabled to measure the gaes, and to notice the diminution of volume resulting from their spontaneous reaction, or that which may be induced by the ignition of the wire. 820. The volumescope being so far prepared, and the tube exhausted of air so as to become full of water, close the cock leading to the air pump, and introduce two volumes of pure hydrogen and one volume of pure oxygen, which may be most con- veniently and accurately effected by the sliding-rod gas measure. The plates of the calorimotor being in the next place excited by the acid, the ignition of the platinum wire ensues, and causes the hydrogen and oxygen to explode. When they are pure, the subsequent condensation is so complete, that the water will produce a concus- sion as it rises forcibly against the gum elastic disk, which, aided by the mahogany block, closes the upper orifice of the tube. 821. If the preceding experiment be repeated with an excess of either gas, it will be found that a quantity, equal to the excess, will remain after the explosion. This is very evident when the excess is just equal to one volume, because, in that case, just one volume will remain uncondensed. By these means, a satisfactory illustration is afforded of the simple and invariable ratio in which the gaseous elements of water unite, when mixed and inflamed ; which is a fact of great importance to the atomic theory, and to the interesting theory of volumes which hereafter I shall have oc- casion to notice. 822. Since the accompanying engraving was made, a plate of brass, about a half an inch in thickness, has been substituted for the mahogany block. This plate was made true by means of the slide lathe, the holes for the cocks entering upon the side, and extending inwards and downwards, so as to open into the bore of the tube, when the plate is in its place. 823. It has been found to contribute much to convenience in manipulating with this instrument, to have a vessel, an iron mercury bottle, for instance, such as re- presented in page 69, (398,) interposed between the air pump employed, and the volumescope, so as to be exhausted before performing an experiment. Thus as- sisted, in order to cause the tube to be filled with water, it is only necessary to turn the key of the proper cock. Moreover, by this expedient, the water is prevented from reaching the pump, and when corrosive vapours are produced, lessens the danger of their injuring the mechanism of that instrument. COMPOUNDS OF HYDROGEN WITH OXYGEN. Of Water. 824. This liquid may be produced by the combustion of hydrogen gas with oxygen . gas. It may be decomposed by passing it in steam over iron, ignited in a gun barrel ; also by the aid of acids, by the alkaline metals, by sul- phurets and phosphurets, by electricity, by galvanism, and by vegetable leaves. 825. Water is necessary to some crystals and to gal- HYDROGEN. 151 vanic processes. Its powers as a solvent are peculiarly extensive, and are increased by heat and pressure. 826. Water is one, among other substances, which acts as an acid with powerful bases, while with powerful acids its acts as a base. Berzelius, in some instances, calls it hydric acid. It will be seen, as we proceed, that it com- bines with various metallic oxides, especially those which constitute the alkalies and alkaline earths. With the lat- ter especially it produces much heat in combining, as ex- emplified in the slaking of lime ; and in several of its com- binations with them, its affinity is too energetic to be overcome by any degree of heat. Excepting acids, any compound in which water exists as an essential constituent, is called a hydrate. Thus slaked lime is a hydrate of lime ; but this term is inappropriate, when applied to the compounds which it forms with acids. To them the term aqueous is applied by Berzelius. The absence of water -in any substance in which it is liable to be present, is signi- fied by the word anhydrous. I infer then that its presence should be indicated by means of the adjective hydrous. The vaporization and evaporation of water has, I trust, been sufficiently illustrated. (177, 229, 234.) As a moving power for machinery, as the source of rain, and as the cause of earthquakes, aqueous vapour is, obviously, for good or for evil, one of the most potent agents of nature. The equivalent of oxygen being 8 And that of hydrogen 1 Water is represented by 9 Experimental Illustrations of the Agency of Water. 827. No reaction ensues between tartaric acid and car- bonated alkali until water is added, when a lively efferves- cence ensues. 828. Concentrated sulphuric acid and zinc remain inac- tive until water is added, when a copious evolution of hydrogen follows. 829. If nitrate of copper be rolled up in tin foil without moisture, the mass will remain inert; but if moistened before it is rolled up, ignition will be produced. 152 INORGANIC CHEMISTRY. Aqueous Vapour or Steam decomposed by ignited Iron. 830. Having introduced some turnings of iron or refuse card teeth into an old musket barrel, lute into one end of it the beak of a half-pint glass retort, about half full of water; into the other end, a flexible leaden tube. Lift the cover off the furnace, and place the barrel across it, so that the part containing the iron turnings may be exposed to the greatest heat. Throw into the furnace a mixture of charcoal and live coals. The barrel will soon become white-hot. In the interim, by means of a chauffer of coals, the water being heated to ebullition, the steam is made to pass through the barrel in contact with the heated iron turnings. Under these circumstances, the oxygen of the water unites with the iron, and the hydrogen escapes in the gaseous state through the flexible tube. 831. The decomposition of water by sulphurets, phos- phurets, and the alkaline metals will be illustrated in due time. Water produced by an inflamed Jet of Hydrogen. 832. The recomposition of water may be rendered evi- dent, by means of the philosophical candle, (305,) or any other inflamed jet of hydrogen, situated within a large Apparatus for the Recomposition of Water. (Page 153.) HYDROGEN. 153 glass globe. The glass becomes immediately covered with a dew, arising from the condensation of aqueous vapour, produced by the union of the oxygen of the air with the hydrogen. Lavoisier's Apparatus for the Recomposition of Water. 833. This apparatus consists of a glass globe, with a neck cemented into a brass cap, from which three tubes proceed, severally communicating with an air pump, and with reservoirs of oxygen and hydrogen. It has also an insulated wire for pro- ducing the inflammation of a jet of hydrogen by means of an electric spark. In order to put the apparatus into operation, the globe must be exhausted of air, and supplied with oxygen to a certain extent. In the next place, hydrogen is allowed to enter in a jet, which is to be inflamed by an electric spark. As the oxygen is con- sumed, more is to be admitted. 834. I have employed a wire ignited by galvanism to inflame the hydrogen in this apparatus, and conceive it to be a much less precarious method than that of employ- ing an electrical machine, or electrophorus. (839). Description of an improved Apparatus for the Recomposition of Water. 835. This apparatus is represented by the opposite engraving. An inverted bell glass, with a conical neck, is so closed at the apex in the making, as to form a trans- parent converging cavity, suitable to render the presence of a very small quantity of any contained liquid perceptible to the eye. 836. By means of the screw rod and plate frame, (248,) this bell glass is secured in an inverted position and made air-tight. With the aid of three valve cocks, V V V, and as many leaden pipes, communications with an air pump, a barometer gauge, and a receiver sufficiently supplied with oxygen, may be severally opened or closed at pleasure. Through a stuffing box which surmounts the plate, a copper pipe, P 20 154 INORGANIC CHEMISTRY. \ is so passed as to occupy the axis of the bell glass, and that of a coil of platinum wire, appertaining to a galvano-ignition apparatus, (335, &c.) The copper pipe ter- minates below in a small platinum tube, and above, outside of the receiver, in a cock C, and gallows screw, by which and a leaden pipe, a communication with a self-regulating reservoir of hydrogen is at command. 837. The apparatus having been thus arranged, the bell is to be exhausted, and oxygen admitted, until the gauge indicates the pressure within the receiver to be nearly the same as that of the atmospnere. In the next place, the platinum wire being ignited, a jet of hydrogen is admitted, which of course inflames, and continues to burn so long as the supply of the gases is kept up. Soon after the inflammation of the hydrogen, the resulting water will be seen to coat the interior of the bell glass in drops, resembling a heavy dew, and, continuing to accumulate, will descend in streams into the converging neck of the bell glass. By surrounding this with cold water, the condensation may be expedited, and the deposition of water soon rendered strikingly evident. The gauge employed in this process is that already described. (137, &c.) 838. Of the Air in Water. Water naturally contains f air. It is to receive the influence of the oxygen of the air thus' existing in water, that fishes are furnished with gills, which perform to a certain extent the office of lungs in de- carbonizing blood. Fishes cannot live in water which, either by boiling or exhaustion, has been entirely deprived of air. 839. The habitudes of other gaseous substances with water will be more advantageously illustrated, when those substances are under consideration. Experimental Proof of the Presence of Air in Water. 840. Water exposed to the action of an air pump, or otherwise subjected to exhaustion, becomes replete with air bubbles. 841. Of the Moisture in Air. Air is not more invariably attendant upon water than water is upon air; nor is the air in water more necessary to fishes, than the water in the air to animals and vegetables. (229, &c.) 842. The well known deleterious influence of the winds which blow from the African deserts, arises probably from their aridity. The desiccating power of air is directly as its temperature, and inversely as the quantity of moisture previously associated with it. 843. There is a certain proportion of moisture, rela- tively to the temperature, which is most favourable to our comfort. If the moisture be increased without raising the temperature, or the temperature be increased without an accession of moisture, we are incommoded. In the one case, the skin becomes unpleasantly dry; in the other, the air is too much encumbered with aqueous vapour, to allow HYDROGEN. 155 perspiration, whether sensible or insensible, to proceed with sufficient freedom. 844. Stove rooms are oppressive on account of the too great aridity of the air in them; and hence the well known remedy of a basin of water, placed upon the stove to fur- nish moisture by its evaporation. 845. Hygrometric Process of Dalton. The dew which is observable on vessels containing cold water, in warm weather especially, arises from the condensation of the aqueous vapour in the air. 846. According to Mr. Dalton, the less the degree of cold requisite to produce this phenomenon, the greater the quantity of moisture in the air. Hence, by ascertaining the highest temperature at which the water is capa- ble of producing the condensation, the quantity of moisture may be known from a table which he has constructed. (229, &c.) 84?. DanielVs Hygrometer. Mr. Daniell has contrived an hygrometer upon the principle thus suggested by Dalton. Vaporization is ingeniously applied to produce cold in one bulb of the instrument, in consequence of the cold produced by the evaporation of ether in another bulb, as in the cryo- phorus. (407, &c.) Two thermometers accompany the instrument, one within the bulb refrigerated by the vaporization; the other so situated as to indicate the temperature of the atmosphere. As the quantity of aqueous vapour in the air diminishes, the depression of temperature necessary to the precipitation of moisture on the refrigerated bulb increases. The extent of the depression is ascertained by the thermometers, the quantity of water in the air by reference to a table. 848. Organic Sensibility of the Beard of the Wild Oat (Avena Sen- sitiva) to Moisture. Hygrometers have been made which are dependent upon the contraction or dilatation which catgut, whalebone, and other sub- stances of a like nature undergo, in proportion to the quantity of moisture in the air. Among instruments of this kind, that formed by means of the beard of the wild oat is pre-eminent for its susceptibility to the influence of moisture. Breathing on it through a minute hole in the case, causes the index to be moved instantaneously. (222, &c.) The indications of hygro- meters thus constructed are not referrible to any standard, agreeably to which a comparison can be made between the dryness of the air in dif- ferent places at the same time, or in the same place at different times. 849. Hygrometric Process by means of a Balance. It may be pre- sumed that the quantity of moisture in the air is inversely as the weight of water which will in a given time evaporate from a moist sur- face. If this presumption be correct, the little square dish here represented may, with the aid of a delicate scale beam, be used as an hygrometer. If it be suspended to the ba- lance, and equipoised while containing a little water, the counter-weight will in a few minutes preponderate, in conse- quence of the loss by evaporation. 850. The loss of weight within any known period being determined, the evaporating power of the air will be as the loss of weight; but as the eva- poration is more or less rapid in proportion as there may be more or less agitation, it will not be right to infer that the quantity of aqueous vapour in the atmosphere is inversely as the rate of evaporation, unless the process 156 INORGANIC CHEMISTRY. were uninfluenced by the wind. Of course the dish should be of convenient dimensions, accurately determined ; 2 inches square for instance. Compounds of Chlorine with Water. 851. Hydrate of Chlorine. Berzelius observes that chlorine furnishes the only instance of an elementary substance capable of entering into com- bination with water. I allude here to a crystalline compound formed on passing the gas through that liquid at a temperature below 40 F. The hydrate thus formed is capable of being sublimed from one part of the con- taining vessel to another, in consequence of a slight diversity of tempera- ture. It consists of one volume of chlorine, and twenty volumes of aqueous vapour. 852. Solution of Chlorine in Water. The same eminent author al- leges that, in order to obtain a saturated solution of chlorine in water, it is necessary, in the first instance, to expel from the latter all the atmospheric air. Of the Deutoxide or Bioxide of Hydrogen, or Oxygenated Water. 853. In 1818, Thenard discovered that water might be made to receive an additional quantity of oxygen, by dis- solving deutoxide of barium in liquid muriatic acid, preci- pitating the baryta by sulphuric acid, and the chlorine by silver. 854. Properties. The bioxide of hydrogen is as liquid, and as devoid of colour as water. It is nearly inodorous, whitens the tongue, inspissates the saliva, and tastes like some metallic solutions. Applied to the skin, it creates a smarting sensation, more durable in some persons than in others. Its specific gravity is 1.452. Hence, when poured into water, it descends through it like syrup, but is dis- solved by agitation. As it is less easy to vaporize than water, it may be separated from that liquid, by exposure in vacuo over sulphuric acid. (309.) In its most concen- trated form, it has not been congealed by any degree of cold to which it has been subjected. The most surprising property of this substance is that of giving off oxygen explosively, on being brought into contact with* substances which do not unite with either of its ingredients. Thus it explodes by contact with finely divided silver, platinum or gold, and still more actively with oxide of silver or perox- ide of lead. The difficulty of explaining these phenomena has already been noticed. (421, &e.) 855. When mingled with the mineral acids, its liability to decomposition is diminished. If exposed to heat in its HYDROGEN. 157 most concentrated state, a few grains create a violent ex- plosion. When, by dilution with 20 parts of water and exposure to heat, it loses all the oxygen which it holds be- yond the quantity necessary to the composition of water, as much oxygen is found to be evolved as the hydrogen in the residual water retains. Hence it is generally supposed to consist of one atom of hydrogen and two of oxygen. Remarks on Nomenclature. 856. Some of the most eminent European chemists have, most errone- ously and inconsistently, designated the acids formed by hydrogen, with the electronegative, or basacigen bodies, as hydracids ; while analogous com- pounds, formed by other radicals, were designated by prefixing syllables indicative of the electro-negative ingredient. Thus we have had hydro- chloric, hydrobromic, hydroiodic, hydrofluoric, hydrocyanic, &c., to sig- nify the acid compounds of hydrogen with the halogen elements ; while we have had fluoboric and fluosilicic to signify acids formed with the ra- dicals boron and silicon by fluorine. Thus the former series is character- ized by letters taken from the radical, the latter by letters taken from the electro-negative or basacigen ingredient, while hydrogen is placed by the side of oxygen, with which, in properties, it is extremely discordant. (633, 636.) 857. This error I pointed out in an article published in the Journal of Pharmacy, in the autumn of 1833, and in a letter to Professor Silliman.* * The following passage is in the letter to which I have referred. " In common with other eminent chemists, Berzelius has distinguished acids in which oxygen is the electro-negative principle, as oxacids, and those in which hy- drogen is a prominent ingredient, as hydracids. If we look for the word radical in the table of contents of his invaluable Treatise, we are referred to p. 218, vol. 1st, where we find the following definition, " the combustible body contained in an acid, or in a salijiable base, is called the radical of the acid, or of the base." In the second vol. page 163, he defines hydracids to be " those acids which contain an electro- negative body combined with hydrogen;" and in the next page it is stated, that "hy- dracids are divided into those which have a simple radical, and those which have a compound radical. The second only comprises those formed with cyanogen and sul- phocyanogen." Again, in the next paragraph, " no radical is known that gives more than one acid with hydrogen, although sulphur and iodine are capable of combining with it in many proportions. If at any future day more numerous degrees of acidi- fication with hydrogen should be discovered, their denomination might be founded on the same principles as those of oxacids." Consistently with these quotations, all the electro-negative elements forming acids with hydrogen are radicals, and of course, by his own definition, combustibles; while hydrogen is made to rank with oxygen as an acidifying principle, and consequently is neither a radical nor a com- bustible. Yet, page 189, vol. 2d, in explaining the reaction of fluoboric acid with water, in which case fluorine unites both with hydrogen and boron, it is mentioned as one instance among others in which fluorine combines with two combustibles. " I am of opinion that the employment of the word hydracid, as co-ordinate with oxacid, must tend to convey that erroneous idea, with which, in opposition to his own definition, the author seems to have been imbued, that hydrogen in the one class, plays the same part as oxygen in the other. But in reality, the former is emi- nently a combustible, and of course the radical by his own definition. " Dr. Thomson, in his system, does not recognise any class of acids under the ap- pellation of hydracids, but, with greater propriety as I conceive, places them under names indicating their electro-negative principles. Thus he arranges them as oxy- gen acids, chlorine acids, bromine acids, iodine acids, fluorine acids, cyanogen acids, sulphur acids, selenium acids, and tellurium acids. These appellations might, I 158 INORGANIC CHEMISTRY. Afterwards I had the satisfaction of observing, that, in an edition of his Traite, then in the press, Thenard was acting upon a similar view of this subject, and employing the language which I had suggested. Moreover I found that Dr. Thomson had not arranged the acids alluded to under the name of hydracids, but had put each of them under the name of its electro- negative ingredient. Hence they were treated of under as many heads as there are basacigen bodies. Or, to be more particular; they were treated of as oxygen acids, chlorine acids, bromine acids, iodine acids, fluorine acids, cyanogen acids, sulphur acids, selenium acids, and tellurium acids. 858. Consistently with the process of abbreviation by which oxacid has been employed to designate an acid formed by oxygen, and hydracid to signify an analogous combination formed with hydrogen, I have made the following abbreviations of the appellations employed by Thomson : For Oxygen acids to use Oxacids. Chlorine acids Chloracids. Bromine acids Bromacids. Iodine acids lodacids. Fluorine acids ,, Fluacids. Cyanogen acids Cyanacids. Sulphur acids Sulphacids. Selenium acids, Selenacids. ,, Tellurium acids Telluracids. 859. The acids formed by oxygen received their names, for the most part, before the basacigen bodies were recognised as elements, or the exist- ence of some of them discovered. Hence, in the case of the oxacids, it is neither customary nor expedient, to prefix any syllables indicating their basacigen ingredient. Consequently, we have sulphuric, selenic, telluric, chloric, bromic, iodic, &c. &c. instead of oxysulphuric, oxyselenic, oxy- telluric, oxychloric, oxybromic, oxiodic, &c.' The syllables were employed prior to the recognition of the elementary character of chlorine, to desig- nate an oxacid with an extra proportion of oxygen. Thus chlorine was think, be advantageously abbreviated into oxacids, chloracids, bromacids, iodacids, fluacids, cyanacids, sulphacids, selenacids, telluracids. " I had formed my opinions on this subject before I was aware that Dr. Thomson had resorted to this classification. " As respects the acids individually, I conceive that it would be preferable, if the syllable indicating the more electro-negative element had precedency in all, as it has in some cases. The word hydrofluoric does not harmonize with fluoboric, fluo- silicic, fluochromic, fluomolybdic, &c. Fluorine being in each compound the electro- negative principle, the syllables, indicating its presence, should in each name occupy the same station. These remarks will apply in the case of acids formed with hydro- gen by all principles which are more electro-negative. Hence we should use the terms chlorohydric, bromohydric, iodohydric, fluohydric, cyanhydric, instead of hy. drochloric, hydrobromic, hydriodic, hydrofluoric, hydrocyanic. " As by the British chemists the objectionable words have not been definitively adopted, the appellations muriatic and prussic being still much employed, it may not be inconvenient to them to introduce those which are recommended by consistency. In accordance with the premises, the acids formed with hydrogen by sulphur, seleni- um, and tellurium, would be called severally sulpbydric. selenhydric, and telluhydric acid. Compounds formed by the union of the acids, thus designated, with the bases se- verally generated by the same electro-negative principles, would be called sulphy- drates, selenhydrates, and telluhydratcs, which are the names given to these com- pounds in the Berzelian nomenclature. Influenced by the analogy, a student would expect the electro-negative ingredient of a sulphydrate to be sulphydric acid, not a sulphide. The terminating syllable of this word, by its associations, can only convey the conception of an electro-positive compound." HYDROGEN. 159 miscalled oxymuriatic acid, being supposed to be an oxide of an unknown radical, with an extra dose of oxygen. (888.) At this time, oxychloric acid designates the acid which has more oxygen than the chloric acid. 860. The analogy between the acids formed by hydrogen with the halo- gen bodies, chlorine, bromine, iodine, fluorine, and cyanogen, render it both desirable and practicable to treat of them in a body, mainly by reference to chlorohydric acid. Hence I shall employ the word halokydric, to desig- nate those acid compounds; and in obedience to similar considerations, the compounds formed with hydrogen by the amphigen bodies, sulphur, sele- nium, and tellurium, will be designated as amphydric acids. 861. The compound formed by the union of hydrogen with oxygen, the protoxide of hydrogen, (water,) ought not to be included under the head of the amphydric acids. Of this oxide, the pretensions to the characteristics of a base, are at least as high as those which can be advanced for it as an acid. Of course it cannot, with propriety, be classed with any acid com- pounds. It is in reality an anomalous substance, performing a part in na- ture of such pre-eminent importance, as to merit to a certain extent an iso- lated position, and undivided attention. 862. Names of the halohydric acids, or those formed by the Jive halogen bodies, chlorine, bromine, iodine, fluorine and cyanogen, with hydrogen, as heretofore given by the French chemists, also by Berzelius, Turner, and others, contrasted with those now employed in this Compendium, agreeably to the practice of Thenard, and with the approbation of Ber- zelius.* For hydrochloric use chlorohydric. hydrobromic bromohydric. hydroiodic iodohydric. hydrofluoric fluohydric. hydrocyanic cyanohydric. 863. Names of the amphydric acids, or acids formed by the amphygen bodies of Berzelius (excepting oxygen} with hy- drogen. For hydrosulphuric use sulphydric. hydroselenic selenhydric. hydrotelluric telluhydric. * I cheerfully admit that it would be preferable to employ the word chlorohydric, instead of hydrochloric. My motive for retaining this last, was, that I was unwill- ing to venture upon a new nomenclature in a language foreign to me, in which it was inexpedient to make changes which could be avoided without inconvenience. I also agree with you, that we ought not to use combustible and oxidable, as having the same meaning. I have deserved your strictures for this inconsistency in my language; but I must suggest as an apology, that the two words were formerly used as synonymous, and that the work, in which you have recently noticed this over- sight, was first published in 1806, having been from time to time remoulded for new editions, without its having been possible to eradicate all that has not kept pace with the progress of science. 160 INORGANIC CHEMISTRY. COMPOUND OF HYDROGEN WITH CHLORINE. Of Chlorohydric or Muriatic Acid Gas. 864. When hydrogen and chlorine are mixed in equal volumes they combine spontaneously. In the dark, or where the light is feeble, the union is slowly accomplished, but, in the solar rays, takes place explosively. According to Silliman, the direct rays of the sun are not necessary to produce the result. The mixture may also be exploded by the electric spark, or by contact with any ignited matter. However the union may be effected, chlorohydric or mu- riatic acid gas is produced, without any reduction of vo- lume if no water be present. Synthesis of Chlorohydric Acid Gas. 865. In order to demonstrate the "ratio in which chlo- rine and hydrogen combine, it is only necessary to intro- duce and ignite in the volumescope over water, equal mea- sures of each gas. If they be pure, there will be a complete condensation. The experiment is conducted precisely as in the case of oxygen and hydrogen, excepting that in lieu of a half volume of oxygen, a volume of chlorine is sup- plied from a self-regulating reservoir. (798.) Explosive Reaction of Hydrogen with Chlorine, under the influence of the Solar Rays. 866. A flask is half filled with |W chlorine over the pneumatic cis- tern in the usual way, and then transferred to the pan P, so as to have its orifice exactly over that of a pipe which, at the other end, communicates with the cock C, to which is annexed a flexible pipe extending to a self- regulat- ing reservoir of hydrogen. (799.) 867. "The flask is surrounded by a wire gauze, W, and just be- fore the explosion is desired, hy- drogen from the reservoir is al- lowed to occupy that portion of the cavity which was previously unoccupied by the chlorine. It should be understood that the pan, during this operation, retains a sufficient stratum of water to cover the mouth of the flask, and that this is occupied with the same liquid in part until it is displaced by the hydrogen. 868. The preliminary arrangements being made, a mirror must be placed HVDROGEN. 161 in a situation to receive the solar rays without passing through window glass, and to reflect them upon the flask. The result is an explosion, from the effects of which the spectators are protected by the wire-gauze. 869. It must be obvious that this experiment can only succeed when the sun is unobscured. 870. It should be understood that the condensation arises altogether from the absorption of the gas by the water. (866.) Preparation of Chlorohydric or Muriatic Acid Gas. 871. Into a tubulated retort, introduce about as much chloride of sodium (common salt) as will occupy nearly one-third of the body, A. Lute a glass funnel, furnished with a cock, into the tubulure. Let the orifice of the beak, B, be so depressed below the surface of the mercury in the cistern, as to be under a bell glass, filled with, and inverted over, the mercury, and properly situated for receiving any gas which may escape through the beak. Prepare about three-fourths as much strong sulphuric acid by weight as there may be salt in the retort. After pouring about one- third of the acid into the retort, close the cock of the fun- nel: the mixture will rise in a foam, and a portion of gas- eous matter will, pass into the bell. As soon as the foam subsides, add more of the acid until the whole is intro- duced. Then as soon as the foam again subsides, apply the chauffer, C, and chlorohydric acid gas will continue to be copiously evolved. I have of late substituted for the funnel a glass tube of about a half an inch in bore at one end, tapering, at the other end, to an orifice of about the eighth of an inch in bore. This tube, being inserted into the retort through the tubulure, and luted thereto air-tight, 21 162 INORGANIC CHEMISTRY. affords a channel for the gradual introduction of the acid, which, surrounding the lower orifice of the tube, prevents the gas from escaping. 872. Rationale of the Process. The water combined with the sulphuric acid is decomposed; its oxygen unites with the sodium, forming soda, with which the sulphuric acid combines, forming sulphate of soda. The hydrogen of the water and the chlorine escape as chlorohydric acid gas. 873. Properties. Chlorohydric acid has all the attri- butes of a gas. It is colourless, and, although less active than chlorine gas, is to the organs of respiration intolera- bly irritating, and if not very dilute, deleterious to life. On escaping into the air, it produces white fumes, from its meeting with moisture. Its affinity for water is so great, that this liquid will take up 420 times its bulk, and when in this state, ice is liquefied as if surrounded by fire. When brought into contact with the metals which decom- pose water, its hydrogen is liberated, while the chlorine unites with the metal. Equal weights of potassium sepa- rate the same weights and volumes of hydrogen from chlo- rohydric acid, and from water; a result conformable with the inferred atomic composition of both. Presented to me- tallic oxides, a reciprocal decomposition ensues ; the hydro-, gen unites with the oxyen generating water, the chlorine with the metal producing a chloride. If mingled with oxy- gen and exposed to the action of heat or a succession of electric sparks, gaseous chlorohydric acid is partially de- composed. This result cannot be extended to more than sVth of the whole volume. At the temperature of 50, and under a pressure of forty atmospheres, it becomes a colour- less liquid. 874. Its specific gravity is 1.2694, a mean between that of its constituents. The weight of 100 cubic inches is 39.36 grains. One atom of chlorine, equivalent 36 And one atom of hydrogen, equivalent 1 Constitute one atom of chlorohydric acid gas, equivalent 37 HYDROGEN. 163 Experimental Illustrations. 875. Equal volumes of hydrogen and chlorine, being mixed and subjected to the solar rays, (867,) or galvanic ignition, (818,) explode and form chlorohydric acid gas. 876. Gas collected over mercury in tall jars. Water, coloured by litmus, being introduced, rapidly changes to a red colour, and causes the disappearance of the gas. Same effect produced by ice, which is rapidly melted. Preparation of Liquid Chlorohydric or Muriatic Acid. 877. It may be obtained by saturating water with the gas in Woulfe's apparatus. (See the following figure.) The solution is nearly pure in all the receptacles excepting the first. Woulfe's Apparatus. 878. By this figure Woulfe's apparatus is depicted in an improved form. The gas evolved in the retort, first passes into the globe where any vapour which may accompany it condenses. It then proceeds along the tube which establishes a com- munication with the bottle next to the globe. As that mouth of this tube which is within the bottle, is below the surface of the liquid placed there to absorb it, the gas has to bubble up through the liquid, so as to promote its own absorption by the agi- tation thus induced. It then rises above the surface of the liquid, where a further absorption takes place. The excess of gas, beyond the quantity absorbed by the li- quid in the first bottle, passes, by means of the connecting tube, to the second bottle, and whatever portion is not there absorbed, reaches the third bottle, in the case of which the process proceeds as in that of the first two. Should any of the gas escape the whole series, it may, by lengthening the last tube, be conducted under a bell glass filled with water on the shelf of the hydro-pneumatic cistern, so as not to an- noy the operator. But this never takes place in the case of chlorohydric acid gas, until the water is nearly saturated. 879. Supposing the extrication of gas to cease before the liquid in the first bottle is saturated, the absorption continuing, the liquid in the second bottle might be trans- ferred to the first, in consequence of the rarefaction of the residual gas rendering it incompetent to resist the atmospheric pressure. In like manner the contents of the third bottle might be transferred to the second. To prevent these inconveniences, there is in each bottle a straight tube fastened air-tight into an intermediate neck, and descending into the liquid. By these means an adequate pressure is opposed to the escape of the gas, and yet any diminution of pressure, arising from absorption, will be compensated by the ingress of atmospheric air, ere the liquid can be drawn over from the next bottle. To prevent absorption from the first bottle into the globe, it is best to use, for the introduction of the acid, a trumpet-mouthed tube of small bore, passing through and luted into the tubulure by a cork with lead and a gum elastic bandage, and terminating in a small orifice near the bottom of the retort inside. 164 INORGANIC CHEMISTRY. 880. Of late I have resorted to the following expedient. The beaks of four tubu- lated retorts, are drawn out by heating them in a hole opened by a poker in an an- thracite fire, until the beak, by its own weight, is made to extend itself into a long tapering tube. At the moment when this takes place, by lifting it from the fire and holding the body of the retort in a suitable position, the tapering portion of the beak hangs down, making the desired angle with the other part of the beak. Of course it retains this form when cold. The retorts thus prepared, are so associated th,at the beak of No. 1, the larger retort, may enter No. 2, through the tubulure of No. 2, and that the beak of this may in like manner reach into No. 3. Of course a fourth and a fifth retort may, if requisite, be thus made to communicate. The beaks are to be luted to the tubulures; and No. 1, being supplied with the salt, and furnished with a tapering tube for the introduction of the sulphuric acid, the process is to be conducted as al- ready described. (873, &c.) 881. Commercial chlorohydric acid is so cheap, that I have found it preferable to use it in the first retort, instead of salt. The addition of sulphuric acid causes the gas to come over pure, without heat at first, but with the aid of a gentle heat, nearly the whole may be evolved, and of course absorbed by the water, placed purposely within retorts, No. 2 and 3. It is preferable to add a fourth retort, and to have No. 2 quite small, holding only a small quantity of water, just adequate to wash out of the gas any sulphuric acid which may attend it in the form of a spray. It may be remarked, that one advantage of this process is, that the iron which is usually an impurity in liquid chlorohydric acid, forms a compound with sulphuric acid, which is not like the chloride of that metal, volatile. Consequently, by this process, the acid is depurated of iron. 882. Liquid chlorohydric acid may also be obtained by distilling a solution of chloride of sodium in water with sulphuric acid. In this way there is no need of an apparatus for promoting absorption, as described in the preceding article. The acid comes over and condenses in union with the requisite quantity of water. 883. Properties of the Liquid Chlorohydric Acid. When concentrated, it produces suffocating fumes from the es- cape of gas. When pure, it is colourless, though usually straw-coloured from the presence of a minute portion of iron. 884. Dr. Thomson informs us that the strongest liquid acid which he could obtain, consisted of one atom of acid, equivalent 37, united with six atoms of water, which being equivalent to 54, the proportion of acid to water by weight was as those numbers, or nearly as 2 to 3.* * The relative equivalent proportion of chlorohydric acid and water, or proportion of said acid, by weight, in aqueous solutions of different specific gravities, may be learned from the following table. (See Thomson's Principles of Chemistry.) Atoms of Acid. Atoms of Water. Real Acid in 100 of the Liquid. Specific Gravity. I 6 40.659 1.203 7 37.000 1.179 8 33.945 1.162 o 31 .346 .149 10 29.134 .139 11 27.200 .1285 12 25.517 .1197 13 24.026 .1127 14 22.700 .1060 15 21.512 .1008 16 20.442 .0960 17 19.474 .0902 - 18 18.590 .0860 19 17.790 .0820 20 17.051 .0780 HYDROGEN. 165 Experimental Illustrations. 885. Liquid chlorohydric acid exhibited; also its reac- tion with other bodies. Of the Old Theory of the Nature of Chlorine and Chlorohydric Acid. 886. Chlorohydric acid was deemed to be a compound of oxygen with some unknown radical. When distilled from red oxide of lead, or black oxide of manganese, it was supposed to combine with a portion of the oxy- gen of those oxides, forming oxygenated muriatic acid, the name then given to chlorine. To the oxygen thus imagined to exist in it, the activity of chlorine, as a supporter of combustion and as a solvent of metals, was ascribed. It has since been proved that neither carbon nor the metals are oxidized when intensely ignited in dry chlorine. ' The metals are converted into chlorides, while the carbon undergoes no change. Chloride of sulphur and bichloride of phosphorus, which result from saturating these substances with dry chlorine, are devoid of acidity; but the addition of water converts the one into muriatic and phosphorous acid, the other into muriatic and hyposulphurous acid. 887. If chlorine be muriatic acid oxygenated, the discovery of the hypo- chlorous, chlorous, chloric, and oxychloric acids must establish this ano- maly, that the radical of muriatic acid, by successive additions of the same acidifying principle, gains, loses, and regains acidity, forming first an acid, then an oxide, and finally four acids. I have said it forms an oxide, be- cause chlorine must be deemed an oxide, having no acid properties. 888. It has been stated, page 156, that Thenard oxygenated the water in liquid muriatic acid; yet this did not convert it into a solution of chlorine. 889. Agreeably to the doctrine now universally sanctioned by chemists, chlorohydric acid, consisting of chlorine and hydrogen, is deprived of hydrogen in all those processes by which it was formerly supposed to be oxygenated. Of Bromohydric Acid. 890. To obtain bromohydric acid, Berzelius recommends that phospho- rus should be placed in contact with bromine under water. The resulting bromide is resolved into phosphoric acid and bromohydric acid gas. The latter may be collected over mercury, or made to produce liquid bromohy- dric acid by union with water, exactly by the same means as have been il- lustrated in the case of chlorohydric acid, which the bromohydric acid much resembles. Bromohydric acid is a colourless gas, in smell similar to chlo- rohydric acid. It has a specific gravity of 2.7353. When brought in con- tact with the air it produces thick fumes. It is decomposed in passing through a tube heated red-hot. It is composed of one atom of hydrogen and one of bromine. Of lodohydric Acid. 891. According to Berzelius, in order to procure iodohydric acid, nine parts of iodine and one of phosphorus should be placed in contact at the bot- tom of a tube or small matrass, and protected from the air by powdered glass. Iodide of phosphorus is formed, which is resolved into phosphoric acid and iodohydric acid gas by the gradual affusion of a small quantity of water. The gas cannot be collected over water or mercury, as it acts on 166 INORGANIC, CHEMISTRY. the one and is absorbed by the other. Hence it must be collected in bot- tles, by means of tubes descending through their orifices to their bottoms, which is analogous to the mode, already illustrated on a large scale, for col- lecting chlorine. (666.) This process is even more practicable in the case in point; since iodohydric acid is the heaviest gas known, having a specific gravity of 4.3854, or more than four times as great as that of atmospheric air. In composition and general properties it resembles chlorohydric and bromohydric acid. 892. The compound of hydrogen with fluorine, forming the acid of fluor spar or/uohydric acid, improperly called hydrofluoric acid, will be defer- red for consideration, until boron and silicon have been treated of. COMPOUNDS OF HYDROGEN WITH SULPHUR. 893. It appears probable that hydrogen and sulphur may combine in various proportions. Only two com- pounds, however, have been sufficiently distinguished, to be worthy of a place in this work. One of these is a defi- nite compound of hydrogen and sulphur, containing an atom of each, and has hitherto been called sulphuretted hydro- gen, especially by the British chemists. The other con- tains one atom of hydrogen, with a plurality of atoms of sulphur, which, according to Thenard, may extend to the proportions of four, six, or eight atoms to one. To this he has accordingly given the name of polysulphuret of hy- drogen. 894. Pursuant to the nomenclature of Berzelius, all the electro-negative compounds of sulphur are called sulphides, and are designated by attaching, as an adjective, their ra- dical, with the last syllable changed into ique in French, or ic in English; as, for instance, sulphuretted hydrogen is called by him in French, sulphide hydrique, which in Eng- lish is rendered by hydric sulphide. This gas has by some chemists, especially the French, been called hydrosulphuric acid, by analogy with hydrochloric acid. The term hydro- sulphuric is objectionable from its conveying the idea of aqueous sulphuric acid ; hydro being used to imply the pre- sence or influence of water. I have already pointed out the inconsistency of designating some acids by giving pre- cedence to the syllables representing their radical, as in hydrochloric, hydriodic; while in others, the syllable indi- cative of their electro-negative ingredient has the prece- dence, as in fluosilicic, fluoboric, chlorocarbonic, and chlo- rocyanic. If sulphuretted hydrogen is to receive a new name, I would prefer to call it sulphydric acid, as already suggested. (858, &c.) HYDROGEN. 167 Of Sulphydric Acid or Sulphuretted Hydrogen. 895. Few persons are unacquainted with the unpleasant odour which results from the washings of a gun barrel, made foul by the explosion of gunpowder, or that produced by putrid eggs. This odour arises from a compound con- sisting of one atom of hydrogen and one atom of sulphur. The celebrated sulphur springs of Virginia are indebted for their odour, and mainly for their efficacy, to this compound ; to which the celebrated Thenard has given the name of sulphydric acid. 896.. Preparation. This gas is copiously evolved by the reaction of diluted sulphuric acid with sulphuret of iron. In order to have a supply of it at command, it is only ne- cessary to substitute this last mentioned substance for zinc in the self-regulating apparatus employed for hydrogen, already described. (706.) 897. As it is absorbed by water and gradually decom- posed by mercury, Berzelius recommends that it should be received over brine. Its purity is demonstrated by its com- plete absorption by a solution of caustic potash, and by its not rendering lime-water milky. 898. He also advises that the gas should be passed through water, as otherwise it is liable to be contaminated by the generating materials. When the acid is sufficient- ly diluted, the action in the apparatus above referred to is so gentle, that I am confident from my experience that the gas comes over sufficiently pure for ordinary purposes. Convenient Method of impregnating Liquids with Sulphydric Acid. 899. Suppose the little flask, F, to contain the liquid to be // impregnated, and the flexible pipe, one end of which is inserted // into the orifice of the flask, to proceed from a self-regulating re- servoir of sulphydric acid : it must be evident that the gas, flow- ing into the cavity of the flask from the orifice of the pipe, must enter the solution. If not absorbed as rapidly as it may be yield- ed, the excess must bubble up through the solution 5 the cork being meanwhile loosened to allow the atmospheric air to es- cape. The expulsion of the atmospheric air having been com- pleted, and the cork inserted into the neck of the flask, so as to prevent the gas from escaping, it will continue to enter the flask as fast as absorbed. But if it be generated in the reservoir more rapidly than the solution can absorb it, the excess must remain in the reservoir, and contribute to depress the acid so low in the bell-glass, as to diminish the quantity of the sul- phide on which it can act. Finally, when the solution becomes saturated, the gas generated in the bell must fill it, and thus, by usurping the place of the acid, cause its reaction with the sulphide of iron lo be suspended. 168 INORGANIC CHEMISTRY. 900. Properties. Sulphydric acid is a permanent gas with the odour of rotten eggs, absorbable by water, inflam- mable and explosive, forming, by combustion with air or oxygen gas, water, and a mixture of sulphurous and sul- phuric acids. 901. At the temperature of 50 F., and under a pressure of 17 atmospheres, sulphydric acid becomes a colourless liquid more fluid even than sulphuric ether. 902. Metals are tarnished by it, especially preparations of lead, of which it is a test, and by which it may be detected. It is evolved from privies, blackening the ceruse or carbo- nate of lead in paint. It may be decomposed by various substances, having an affinity for one or both of its consti- tuents, as for instance, by chlorine, potassium, sodium, sul- phurous acid, and ignited carbon; also by successive elec- tric explosions. 903. Sulphydric acid decomposes all metallic solutions, ex- cept those of cobalt, nickel, iron, zinc, manganese, titanium, and molybdenum, in consequence of the attraction between hydrogen and either oxygen or chlorine, and between the metals and sulphur. Metals, which in the metallic state yield hydrogen during their reaction with diluted sulphuric or muriatic acid, afford sulphydric acid, when in the state of a sulphide or sulphuret, subjected to those acids. Ac- cording to Berzelius, some sulphides act as acids, others as bases, and unite with each other in a manner analogous to that in which the oxacids and oxybases combine. The resulting compounds he calls sulpho-salts. Some sulphides are liable to be reduced by exposure to pure hydrogen in a way analogous to that in which oxides are decomposed by the same agent. But the number of sulphides which may be thus decomposed is much smaller. Atmospheric air is said to be rendered deleterious to life by the addition of 2-hrth of this gas. 904. It is alleged that a single cubic inch of the gas, liberated in a large chamber, will in every part be produc- tive of its characteristic unpleasant odour. A current of the gas directed upon the tongue causes an astringent, acid, and bitter taste. The specific gravity of sulphydric acid is 1.1782, that of atmospheric air being 1. It is slowly decomposed by nitric oxide, and by sulphurous acid when moist. Nitroso-nitric acid reacts with it explosively. With sulphurous acid when dry it does not react; but, HYDROGEN. 169 water being present, condensation ensues with a deposition of sulphur, and, according to Thompson, the production of a peculiar acid. At the temperature of 50 F., water takes up three times its bulk of sulphydric acid, which may be entirely expelled by a boiling heat. The aqueous solution reddens litmus, and becomes turbid after some time by ex- posure to the air, with the oxygen of which the hydrogen of the gas combines, while the sulphur precipitates. It has already been stated that water impregnated with sulphy- dric acid exists in many natural springs, which are much frequented by invalids. 905. The celebrated white sulphur, salt sulphur, and red sulphur springs of Virginia, are of this nature. They ap- pear particularly efficacious as remedies for bilious disor- ders, and in cutaneous diseases. 906. The red sulphur springs are thought to be pecu- liarly useful in some pulmonary complaints, and appear to have a surprising and unaccountable influence in lowering the frequency and force of the pulse. Experimental Illustrations. 907. Method of extricating sulphydric acid gas by means of a self-regulating reservoir exhibited; also, the impregnation of water with it. Effects of its aqueous so- lution on litmus, and on various metallic solutions. Cha- racters written with dissolved acetate of lead are black- ened by exposure to the gas, or its aqueous solution. Its inflammation by nitric acid. Sympathetic Picture. 908. The original of this figure (see the engraving at the top of the following page) was drawn of a gigantic size, in acetate of lead, and was invisible at a little distance, until a jet of sulphuretted hydrogen was directed upon it. The image then appeared by the waving of the pipe from which the gas flowed, as if it were the wand of a magician. ltd 1 .). If the acetate has had time to become dry, the experiment will not succeed without restoring a due degree of moisture. This object is best accomplished by passing a wet sponge over the back of the sheet on which the figure has been drawn. 910. Rationale. The acetate of lead consists 'of acetic acid and oxide of lead. The oxygen of the oxide unites with the hydrogen of the gas, while the sulphur and lead form a sulphuret, to which the blackness of the picture is due. 22 170 INORGANIC CHEMISTRY, Of the Polysulphide of Hydrogen. 911. There are various compounds formed by sulphur with metals, some of which are soluble ; as for instance the compound formed by boiling it with lime. This compound has been called a persulphuret of calcium. I would call it a persulphide. Scheele ascertained that on pouring into a di- luted acid a persulphuret, such as that to which I have alluded, an oily looking liquid was precipitated, which subsequently received the name of bisulphuretted hydrogen. Thenard designates this compound as the poly- sulphuret of hydrogen, on account of the great and variable number of atoms of sulphur which enter into its composition. Moreover he alleges that it constitutes a compound analogous in its properties to the deutoxide of hydrogen ; being like that mysterious combination decomposable by many substances for which it has no affinity. Even the presence of the persul- phide employed in its production is incompatible with its existence, and hence the impossibility of forming it by pouring the acid into the solution. In that case an excess of the persulphide must inevitably be present. 912. He alleges that the polysulphuret (polysulphide) is always liquid at ordinary temperatures. Its colour is yellow, sometimes approaching a greenish-brown. It whitens the tongue when applied to it, as is the case upon making a similar application of deutoxide of hydrogen. The same effect is produced upon the skin. Litmus paper is bleached by it, more especially when it is diffused in muriatic acid. Sometimes it has the con- sistency of an essential oil, sometimes of a fat oil, according to the propor- tion of its constituents, which has already been stated to be variable. Its odour is peculiar and disagreeable, especially at the period when, having been recently formed, the supernatant liquid is decanted from it. Then HYDROGEN. 171 also it affects the eyes painfully. Sooner or later it is resolved into its elements spontaneously. Charcoal, platinum, gold, iridium, and many other metals in the pulverulent form, cause the evolution of the hydrogen. Many metallic oxides have the same effect, some so actively as to cause a brisk effervescence. These results also ensue from contact with the deut- oxide or bioxide of manganese, from magnesia, from silica, and above all from pulverized baryta, strontia, lime, potash, and soda. From some of the facts mentioned by Thenard, I infer that this substance may be of great service in bleaching. COMPOUNDS OF HYDROGEN WITH SELENIUM AND TELLURIUM. Of Selenhydric Acid, commonly called Selenuretted Hydrogen. 913. Selenhydric acid is supposed to consist of one atom of selenium, and one atom of hydrogen. It may be obtained from the selenide of potas- sium or of iron, by the action of chlorohydric acid. It is a colourless gas, absorbable without change of colour by water which has been boiled. Water thus impregnated has an hepatic taste, reddens litmus paper, and if applied to the skin, stains it a brownish-red. The solution exposed to the air, by the oxidation of the hydrogen, becomes gradually turbid from the surface downwards, acquiring a reddish hue, and depositing selenium in light flocks. All metallic salts, even those of iron and zinc, when they are neutral, are precipitated by selenhydric acid. The precipitates are generally of a deep black colour, yet those of zinc, manganese, and cerium, are flesh-coloured. By the oxidizement of the hydrogen in selenhydric acid, selenium is pre- cipitated of a cinnabar-red colour on any moist body. This acid exercises upon the respiratory organs a violent action, which might easily become dangerous. It produces at first the odour of sulphydric acid, but soon after a prickling sensation in the membranes of the nostrils, which resembles that created by fluosilicic acid gas, but is more stimulating. Subsequently the eyes become red, and the sense of smell is paralyzed. A single bubble of the gas, received into the nose, caused such a paralysis of the olfactory nerves, as to create insensibility even^to the fumes of the strongest ammo- nia. The power of detecting odours was not recovered before the expira- tion of five or six hours. 914. Thenard mentions that Berzelius, in consequence of inhaling se- lenhydric acid gas, was attacked by a cough so severe, that a blister was deemed necessary. The quantity inhaled was so minute as to give the impression, that, in its effects upon the human system, this gas is pre- eminently pernicious. Of Telluhydric Acid, commonly called Telluretted Hydrogen. 915. When an alloy of tellurium with zinc or tin is exposed to the action of chlorohydric acid, telluhydric acid is evolved. It is a colourless gas, which strongly resembles sulphydric acid in smell and in its chemical and mechanical properties. It reddens litmus paper, is soluble in water, pro- ducing a colourless solution, which by exposure to the air becomes brown, in consequence of the oxidation of the hydrogen and precipitation of the tellurium. It is probably composed of one atom of hydrogen and one of tellurium. 172 INORGANIC CHEMISTRY. 916. The effect of the monosyllable gen, in chemical language, has been explained. (See note, 628.) SECTION II. OF NITROGEN OR AZOTE. 917. In the gaseous state, it forms nearly four-fifths of the atmosphere in bulk. Its ponderable base is a principal element in animal substances. In vegetables, it is only occasionally found. It was called azote, from the Greek *>> life, and *, privative of. It was subsequently named nitrogen, azote being equally applicable to other gases which are destructive of life. I regret that Thenard, in- stead of abandoning the use of this bad word, has lately endeavoured to give it a further hold on nomenclature, by using the words azotous and azotic, in lieu of nitrous and nitric. 918. Consistently with the explanation which has been given of the monosyllable gen, nitrogen signifies a capacity to produce nitric acid, as oxygen conveys the idea of a capacity to produce acids generally. 919. Preparation. Nitrogen may be procured by the aid of any substance which will, in a close vessel, abstract oxygen from the included portion of the atmosphere ; as, for instance, by the combustion of phosphorus, or by iron filings and sulphur moistened. This gas may also be ob- tained by heating muscular flesh in a retort with nitric acid very much diluted. When obtained by means of phosphorus, a minute quantity of this substance remains in solution in the nitrogen ; when extricated by the action of nitric acid, it contains a small portion of carbonic acid. In either case it may be purified by washing it with an alkaline solution, or with lime-water. 920. Another method of obtaining nitrogen gas is to pass chlorine through liquid ammonia. The chlorine unites with the hydrogen of the ammonia, while the nitrogen is liberated. Care must be taken to have the ammonia in excess, otherwise a chloride of nitrogen may be formed, which is capable of producing the most violent explo- sions. 921. When the chlorite of lime (bleaching salt) is min- Abstraction of Oxygen from Atmospheric Air by Phosphorus, (Page 173.) NITROGEN. 173 gled with muriate of ammonia and moistened, nitrogen is evolved. For this purpose Professor Emmet has recom- mended the boiling of nitrate of ammonia upon zinc. Apparatus for obtaining the Nitrogen from Atmospheric Mr. 922. The apparatus represented in the opposite engraving leaves the nitrogen so situated, as to be drawn easily from the containing vessel, in such quantities and at such times as may be desirable. In its principal parts, it does not differ from the gasometer for oxygen. (617.) It is provided with a pipe, p, concentric with the axis of the lower vessel, C, surmounted by a small copper cup. The pipe in question de- scends perpendicularly from the level of the brim of the vessel to the bottom; being soldered into a hole in the latter, so that, the bore being accessible from without, the copper cup at the upper end may, when necessary, be touched with the end of a red- hot iron rod, introduced through the pipe as in burning phosphorus in oxygen. (654, &c.) 923. The inner vessel of the gasometer consists of a bell-glass, B, suspended by a cord passing over a wooden gallows with suitable pulleys. The bell has a perforated neck cemented into a brass cap, furnished with a female screw for receiving a cock. To this cock a flexible lead-pipe is attached by a gallows screw. Upon the copper cup a sufficient quantity of phosphorus being placed, and the lower vessel adequately supplied with water, the bell-glass is suspended within the lower vessel, as is usual with gasometers, and allowed to descend about a third of its depth. Meanwhile, the cock of the tube being open, the air is allowed to escape, so that the liquid within and without the bell-glass may be on a level. The cock being in the next place closed, and the temperature of the phosphorus sufficiently raised to make it take fire by touching the cup with the extremity of an iron rod previously reddened in the fire, a brilliant combustion ensues. As soon as it declines, the iron, meanwhile kept in the fire, should be again introduced, in order to sustain the combustion till all the oxygen is absorbed. 924. When the air in the bell-glass is completely deoxidized, which may be known by the fumes becoming yellow, the residual nitrogen may be expelled into any reci- pient at pleasure, through the flexible pipe attached to the cock for that purpose, by depressing the bell in the water. 925. Properties of Nitrogen Gas. As a gas, it is distin- guished by a comparative want of properties. It is lighter than oxygen gas, or atmospheric air. It supports neither life nor combustion, but is obviously a harmless ingredient in the air. 926. The affinity of nitrogen for caloric, compared with that which it displays for other substances, appears to be peculiarly great. Hence it is not liable, like hydrogen or oxygen, to enter into combination with other matter, so as to part with the caloric to which it owes its existence as a gas ; and when under any circumstances it does enter into combination, it seems, more than almost any other substance, to carry caloric into combination with it ; be- ing, consequently, an ingredient in a majority of the most powerful fulminating compounds. 927. Nitrogen has been suspected by some chemists to be a compound, but is generally considered as an element. At the temperature of 60 F., 100 cubic inches weigh 174 INORGANIC CHEMISTRY. 30.1650 grains. Its specific gravity, comparatively with air, is 0.9727. Experimental Illustrations of the Properties of Nitrogen Gas. 928. A portion of the nitrogen, obtained as above de- scribed, being introduced into a bottle, extinguishes a can- dle flame when introduced into it ; but being mixed with one-fourth of its bulk of oxygen gas, the effect of the mixture in supporting flame is similar to that of atmosphe- ric air. OF ATMOSPHERIC AIR. 929. Atmospheric air is a mixture, not a chemical com- pound, of oxygen and nitrogen gas, with some moisture and carbonic acid, in the following proportions. By Measure. By Weight. Nitrogen gas 77.5 - 75.55 Oxygen gas 21. 23.32 Aqueous vapour 1.42 - - 1.03 Carbonic acid v 0.08 - 0.10 100.00 100.00 930. The average of a great number of experiments, made with my eudiometers, makes the proportion of oxy- gen 20.66 in 100 of air. 931. In addition to these constituents, it is alleged that there is a little chlorohydric acid in the atmosphere, in situations in the neighbourhood of the sea; and hence it arises, probably, that animals far inland, show a much greater avidity for common salt, a compound of chlorine and sodium, than those existing in regions bordering on the ocean. This avidity seems to have been implanted in order to supply a source for the chlorohydric acid, which appears to be requisite to the powers of the gastric fluid. 932. It has been made a question whether the nitrogen and oxygen of the air are not in a state of chemical com- bination. I am of opinion that no other cause of union between them exists than that which is known to produce the equable diffusion of heterogeneous gaseous particles among each other, notwithstanding the difference of their specific gravities. NITROGEN. 175 933. In its qualities atmospheric air does not differ from a mixture. Oxygen, mingled with hydrogen in the same proportion in which it is mingled with nitrogen in the air, has been found to support animal life nearly as well. 934. The mechanical influence of the atmosphere, so far as it appertains to chemistry, has been sufficiently illus- trated, (177, &c.) I have also treated of its capacity to hold moisture, and to promote and produce cold by eva- poration, (229, &c.) Some additional methods of analys- ing it, will be mentioned under the heads of nitric oxide and phosphorus. Eudiometrical Analysis of the Atmosphere. 935. While on the subject of atmospheric air, the eudiometrical analysis of it becomes necessarily an object of attention. I have already given an engraving and description of a large eudiometer, which I have designated as a volumescope. By means of that instrument it was demonstrated, that when the elements of water are mixed in the gaseous state and ignited, they will always combine in the proportion of two volumes of hydrogen to one volume of oxygen. It follows that, if any gaseous mixture containing oxygen, and no other gas capable of combining with hydrogen or oxygen, be ignited with an excess of hydrogen, all the oxygen will be condensed into water, and may be estimated as equal to one-third of the resulting deficit. It follows also that, if, to a gaseous mixture containing hydrogen, and no other gas with which hydrogen or oxygen can combine, an excess of oxy- gen be added and the mixture ignited, all the hydrogen will be condensed, and will in quantity equal two-thirds of the deficit. Thus, if five volumes of atmospheric air and three of hydrogen be introduced into the volume- scope and ignited, the eight volumes will be reduced to rather, less than five; of course a little more than three volumes will have been condensed, of which one-third is oxygen. In five volumes of atmospheric air, there is, therefore, somewhat more than one volume of oxygen. By the volume- scope the excess cannot be accurately measured, but by other instruments which I have contrived, and which I shall proceed to describe, great accu- racy is attainable. I am the more particular in describing my apparatus in the Compendium, that I may not be under the necessity of occupying the brief time allotted to my lectures with such descriptions. Of the Sliding-rod Eudiometer. 936. I have constructed some eudiometers, and gas measures, in which the measurement of gas is effected by a graduated rod, which slides into or out of the cavity of a tube, through a collar of leathers soaked in lard, and compressed by a screw so as to be perfectly air-tight. This rod is em- ployed to vary the capacity of the tube, and at the same time to be a mea- sure of the quantity of air, or of any other gas, consequently drawn in or expelled. About one-third of the tube is occupied by the sliding-rod. The remainder, being recurved, and converging to a perforated apex, is of a form convenient for withdrawing measured portions of gas from vessels inverted over water or mercury. 937. There were two forms of the sliding-rod eudiometer; one designed 176 INORGANIC CHEMISTRY. to be used for explosive mixtures, requiring ignition; the other in analysis dependent upon the absorbing power of a liquid or gas. The former differs from the eudiometers employed by European chemists, in the contrivance for igniting the explosive mixtures, as well as in that for measuring them, galvano ignition (335) being substituted for the electric spark. 938. I shall proceed to describe a sliding-rod eudiometer, for the analy- sis of explosive mixtures, which I designate as aqueous, because water is the confining liquid employed in it. Aqueous Sliding-rod Hydro-oxygen Eudiometer. W W 939. This cut represents a hydro-oxygen eudiometer, in which the measurements are made by a sliding-rod, and the explosions are effected by the galvanic ignition of a platinum wire. 940. In the instrument represented by the preceding cut, the igniting wire is sol- dered into the summits of the two brass wires, W W, which pase through the bottom of the socket S, parallel to the axis of the glass recipient, G, within which they are seen. One of the wires is soldered to the socket. The other is fastened by means of a collar of leathers, packed by a screw, so that it has no metallic communication with the other wire, except through the filament of platinum, by which they are visi- bly connected above, and which I have already called the igniting wire. The glass has a capillary orifice at the apex, A, which is closed by means of a lever and spring (apparent in the drawing,) excepting when the pressure of the spring is counter- acted by the thumb of the operator. The sliding-rod, R, is accurately graduated to about 160 degrees. 941. Experience has shown the expediency of securing the valve which closes the aperture in the apex of the instrument from the possibility of leakage during explo- sions, by means of an iron staple with a screw, represented by the following cut. This fastens upon two pivots, one of which is inserted on each side of the brass socket, S, into which the glass recipient, G, is cement- ed. The staple hinges upon these pivots, and may be brought into a position in which the screw, A, being immediately over the valve, may be made to tighten it; or the staple may be made to hang down, so as not to be in the way when the instrument is to be charged. In order to use the eudiometer, it must be full of water, free from air-bubbles, and previously proved air-tight;* the rod being in- troduced to its hilt, and the capillary orifice open, in consequence of a due degree of pressure on the lever, by which it is usually closed. Being thus prepared to ascertain the proportion of oxygen in the air, draw the rod out of the tube till 100 ^aduations are visi- ble. A bulk of air, equivalent to the portion of the rod thus with- * To prepare the instrument and prove it to be in order, depress the glass receiver below the surface of the water in the pneumatic cistern, the capillary orifice being NITROGEN. 177 drawn, will of course enter at the capillary opening; after which the lever must be allowed to close it. Introduce the receiver into a bell glass of hydrogen, and. open- ing the orifice, draw out the rod as far as an enlargement upon the end will allow it to be retracted. This arrestation will take place just as the 160th graduation becomes visible; and then, in addition to the 100 measures of air previously taken, 60 of hy- drogen will have entered ; next close the orifice, and withdraw the instrument from the water. Apply the projecting wires, W W, severally to the metallic cups, com- municating with the poles of' the calorirnotor represented below* ; then move the handle so as to cause the receptacle holding the acid to rise about the plates. By the consequent ignition of the wire, the gas will explode. The instrument being plunged again into the water of the pneumatic cistern, so that the capillary orifice, duly opened, may be just below the surface, the water will enter and fill up the va- cuity caused by the condensation of the gases. The residual air being excluded by the rod, the portion of the rod remaining without the tube, will be in bulk equiva- lent to the deficit, which may consequently be ascertained by inspecting the gradua- tion. I have performed this experiment in thirty seconds. 942. If oxygen is to be examined by hydrogen, or hydrogen by oxygen, we must of course have a portion of each in vessels over the pneumatic cistern, and succes- sively take the requisite quantities of them, and proceed as in the case of atmos- pheric air. 943. Another and perhaps more accurate mode of operating with this instrument is, by means of one of the volumeters, (see 947, 953 ; ) to make a mixture of the dif- ferent gases, in due proportion, in a bell glass. Thus, let two measures of atmosphe- ric air be added to one of hydrogen ; then on taking one hundred and fifty measures of the mixture into the eudiometer, there will be the same quantity of each gas, as if 50 measures of hydrogen and 100 of air had been taken, as above described. In order to ascertain the quantity of pure oxygen in the gas from nitre or manganese, one measure of it might be added to three of hydrogen. Then of 160 measures of the mixture, which might be taken into the eudiometer, 40 would consist of the gas to be assayed, and 120 of hydrogen; and one-third of the deficit, caused by the ex- plosion, would be the quantity of pure oxygen in the 40 measures. 944. If hydrogen were to be assayed, as, for instance, the gas evolved by the reac- tion of diluted sulphuric acid with zinc, (see page 144,) it would be proper to take equal parts of the hydrogen and oxygen; as the gas which is not to be analyzed must always be in excess. Taking then 160 measures into the eudiometer, two- thirds of the deficit, caused by the explosion, would be the pure hydrogen in 80 measures of the gas under analysis. For the last mentioned process it is preferable to have upon the rod, in addition to the scale of 160 (942), another of 200 degrees, by which means fifty measures of oxygen, or 100 measures of hydrogen, maybe ana- lysed. In this way the per centage of impurity may be more readily perceived. 945. B (see the preceding figure) represents a glass with wires inserted through small tubulures, in the usual mode for passing the electric spark, should this method of producing ignition be deemed desirable, for the sake of varying the experiment, or for the purpose of illustration. This glass, the other being removed, may be fast- ened into the same place. The wires W W, may remain, but should be of such a height as not to interfere with the passage of the electric spark. The instrument is operated with, as usual, excepting the employment of an electrical machine, or elec- trophorus, to ignite the gaseous mixture. For the travelling chemist, the last men- uppermost and open; draw the rod out of its tube and return it alternately, so that, at each stroke, a portion of water may pass in, and a portion of air may pass out. During this operation, the instrument should be occasionally held in such a posture, as that all the air may rise into the glass recipient, without which its expulsion by the action of the rod is impracticable. Now close the orifice at the apex, A, and draw out a few inches of the rod, in order to see whether any air can enter at the junctures, or pass between the collar of leathers and the sliding rod. If the instru- ment be quite air-tight, the bubbles, extricated in consequence of the vacuum pro- duced by withdrawing the rod, will disappear when it is restored to its place. * The figure represents a calorimotor, containing two galvanic pairs, each consist- ing of two plates 'of zinc and three of copper, severally eight inches by nine, for a particular description of which, see my Treatise of Galvanism or Voltaic Electricity. Into two cavities or cups, in two masses of soft solder which constitute the poles of the instrument, the wires, W W, of the eudiometer are forcibly pressed by one hand of the operator, while by the other the acid is made to act upon the plates through the instrumentality of the lever. Instantaneously on the ignition taking place, the circuit should be interrupted by lifting the eudiometer; as otherwise the wire might be fused. 23 178 INORGANIC CHEMISTRY. tioned mode of ignition may be preferable ; because an electrophorus is more porta- ble than a galvanic apparatus. 946. In damp weather, or in a laboratory where there is a pneumatic cistern, or amid the moisture arising from the respiration of a large class, it is often impossible to accomplish explosions by electricity. Sliding-rod Gas Measure. 947. The construction of this instrument, represented by the opposite engraving, differs from that of the sliding-rod eudiometers, in having a valve which is opened and shut by a spring and lever, acting upon a rod passing through a collar of leathers. By means of this valve, any gas drawn into the receiver, is included so as to be free from the possibility of loss, during its transfer from one vessel to another. This instrument is much larger than the sliding-rod eudiometers for explosive mixtures; being intended to make mixtures of gas, in those cases where one is to be to the other, in a proportion which cannot be conveniently obtained by taking more or less volumes of the one than of the other, by means of the volumeters; (948, 954,) for instance, suppose it were an object to analyze the air according to Dr. Thom- son's plan of taking 42 per cent, of hydrogen. The only way of mixing the gases by a volumeter in such a ratio, would be to take the full of the volumeter 21 times of hydrogen, and 50 times of atmospheric air. By the large sliding-rod gas measure this object is effected at once, by taking 42 measures of the one, and 1UO measures of the other. Piston Valve Volumeter. 948. I have contrived some instruments for measuring gas with great accuracy. I call them volumeters to avoid circumlocution. They are of two kinds, one is filled by introducing it into any vessel containing the gas with which it is to be filled, over water or mercury; the gas is introduced into the other through an orifice, as is usual in the case of filling a common bottle over the pneumatic cistern. The fol- lowing figure will convey a correct idea of one of them, which, having a piston and a valve, I call the piston valve volumeter. 949. The lever, L, is attached by a hinge to a piston, p, which works inside of a chamber, C. The rod of this piston extends beyond the packing through the axis of the bulb, B, to the orifice, O, in its apex, where it supports a valve, by which this orifice is kept close, so long as the pressure of the spring, acting on the lever L, is not counteracted by the hand of the operator. 950. Suppose that, while the bulb of this instrument, filled with water or mercury, is within a bell glass containing a gas, the lever be pressed towards the handle; the valve consequently is drawn back, so as to open the orifice in the apex of the bulb, and at the same time the piston descends below the aperture, A, in the chamber. The liquid in the bulb will now of course escape, and be replaced by gas, which is securely included, as soon as the pressure of the spring is allowed to push the piston beyond the lateral aperture in the cham- ber, and the valve into the orifice, O, in the apex of the bulb. 951. The gas, thus included, may be transferred to any vessel, inverted over mercury or water, by depressing the ori- fice of the bulb below that of the vessel, and moving the lever, L, so as to open //III* /AW t ^ ie a P erture > A, in the chamber, and the orifice of the bulb simultaneously. 952. The bulk of gas, included by this volumeter, will always be the same; but the quantity will be as the density of the gas into which it may be introduced when filled. Hence, in order to measure a gas accurately, the liquid, whether water, or mercury, over which it may be confined, A ffilH Ijj /jj should be of the same height within as without. This is especially important in the case of mercury, which, being in .^ ...,,.. ^ weight to water as 13.6 to 1, affects the density of a gas materially; even when its surface within the containing vessel does not deviate sensibly from the level of its surface without. Sliding Rod Gas Measure. (Page 178.) NITROGEN. 179 953. To remove this source of inaccuracy I employ a small gauge, which commu- nicates, through a cock in the neck of the bell, with the gas within. In this gauge any light liquid will answer, wfcich is not absorbent of the gas. In the case of am- monia, liquid ammonia may be used ; in the case of muriatic acid gas, the liquid acid. The gauge is simply an inverted glass syphon, of one of the legs of which cavity is made to communicate with that of the receiver, holding the gas, while the other is open to the atmosphere. Even mercury may be used in such an instrument with sufficient accuracy, because the legs of the syphon being near to each other, the most minute disparity in the heights of the two adjoining columns of the liquid occupying the syphon will be discernible. Simple Valve Volumeter. 954. Besides the lower orifice, O, by which it is filled with gas, the volumeter which this figure represents, has an. orifice at its apex, A, closed by a valve attached to a lever. This lever is subjected to a spring, so as to receive the pressure requisite to keep the upper orifice shut, when no effort is made to open it. 955. When this volumeter is plunged below the surface of the water in a pneumatic cistern, the air being allowed to escape, and the valve then to shut itself under the water, on lifting the vessel it comes up full of the liquid, and will remain so, if the lower orifice be ever so little below the surface of the water in the cistern. Thus situated, it may be filled with hydrogen, proceeding by a tube from a self-regulating reservoir. (797, 798.) If the apex, A, be then placed under any vessel, filled with water and inverted in the usual way, the gas will pass into it as soon as the valve is lifted. 956. Volumes of atmospheric air are taken by the same instrument, simply by lowering it into the water of the cistern, placing the apex under the vessel into which it is to be transferred, and lifting the valve : or preferably by filling it with water, and emptying it in some place out of doors, where the atmosphere may be supposed sufficiently pure, and afterwards transferring the air, thus obtained, by opening the valve, while the apex is within the ves- sel in which its presence is required. In this case, while carrying the volumeter forth and back, the lower orifice must be closed. This object is best effected by a piece of sheet metal, or a pane of glass. It is necessary that the water, the atmosphere, and the gases should be at the same temperature during the process. CHEMICAL COMPOUNDS OF NITROGEN WITH OXYGEN. - 957. These compounds are five in number, nitrous and nitric oxide, and hyponitrous, nitrous, and nitric acid. Their composition is given in the following table: 1 vol. or 1 atom of ni- trogen = 14, forms, with 5 vol. or 1 atom oxygen, 1 vol. nitrous oxide. 1 or 2 atoms 2 vols. nitric oxide. li or 3 hyponitrous acid. 2 or 4 1 vol. nitrous acid. or 5 nitric acid. Of Protoxide of Nitrogen, or Nitrous Oxide. 958. This compound does not exist in nature. When artificially obtained it is gaseous; yet the experiments of 180 INORGANIC CHEMISTRY. Mr. Faraday have taught us that under great pressure, it may be converted into a liquid. 959. Preparation. Nitrous oxide may be obtained by the action of dilute nitric acid upon zinc, or by exposing nitric oxide gas to iron filings, sulphites, or other sub- stances attractive of oxygen. It is best procured by sub- jecting nitrate of ammonia to heat, and receiving the pro- duct in an apparatus described in the following article. As pure water absorbs this gas, Berzelius receives it over a saturated solution of common salt. Apparatus for evolving and collecting Nitrous Oxide. 960. This apparatus is represented by the opposite engraving. A, is a copper ves- sel of about eighteen inches in height, and nine inches in diameter, which is repre- sented as being divided longitudinally, in order to show the inside. The pipe, B, proceeds from it obliquely, as nearly from the bottom as possible. 961. Above that part of the cyliijder from which the pipe proceeds, there is a dia- phragm of copper, perforated like a colander. A bell glass is surmounted by a brass cock, C, supporting a tube and hollow ball, from which proceed on opposite sides, two pipes, terminating in gallows screws, D D, for the attachment of perforated brass knobs, soldered to flexible leaden pipes, E E, communicating severally with leathern bags, F F, of suitable dimensions. 962. The beak of the retort must be long enough to enter the cylinder, so that the gas, in passing from the mouth of the beak, may rise under and be caught by the diaphragm. This is made concave on the lower side so as to cause the gas to pass through the perforations already mentioned, which are all comprised within a circle less in diameter than the bell glass. The gas is, by these means, made to enter the bell glass, and is, previously to its entrance, sufficiently in contact with water, to be purified from the acid vapour which usually accompanies it. On account of this vapour, the employment of a small quantity of water, to wash the gas, is absolutely necessary ; and for the same reason, it is requisite to have the beak of the retort so long as to convey the gas into the water without touching the metal ; otherwise the acid vapour would soon corrode the copper of the pipe, B, so as to enable the gas to escape. But while a small quantity of water is necessary, a large quantity is pro- ductive of waste, as it absorbs its own bulk of the gas. On this account I contrived the apparatus here described, in preference to using gasometers or air-holders, which require larger quantities of water. 963. The furnace, I, is so contrived, that the coals, being situated in a drawer, G, may be partially or wholly removed in an instant. Hence the operator is enabled, without difficulty, to regulate the duration and degree of the heat. This control over the fire is especially desirable in decomposing the nitrate of ammonia, as the action otherwise might suddenly become so violent as to burst the retort. The iron netting, represented at N, is suspended within the furnace, so as to support the glass retort, for which purpose it is peculiarly adapted. The first portions of gas which pass over, consisting of the air previously in the retort, are allowed to escape through the cock, H. As soon as the nitrous oxide is evolved, it may be detected by allowing a jet from this cock to act upon the flame of a taper. 964. To obtain good nitrous oxide gas, it is not necessary that the nitrate of am- monia should be crystallized ; nor does the presence of a minute quantity of muriatic acid interfere with the result. I have employed advantageously, in the production of this gas, the concrete mass formed by saturating strong nitric acid with carbonate of ammonia. 965. The saturation may be effected in a retort, and the decomposition accom- plished by exposing the compound thus formed to heat, without further preparation. 966. Rationale of the Process. Nitrate of ammonia consists of nitric acid and ammonia; nitric acid, of five atoms of oxygen and one of nitro- gen; and ammonia, of one atom of nitrogen and three atoms of hydrogen. 1 (Page 180.) Combustion of Phosphorus in Nitrous Oxide. (Page 181.) NITROGEN. 181 In one atom of this salt, five atoms of oxygen, three of hydrogen, and two of nitrogen are, therefore, present. It must be evident that if, in conse- quence of the heat, each atbm of hydrogen takes one of oxygen, there will be but one atom of oxygen left for each atom of nitrogen. Hence, the whole of the salt is resolved into water, and protoxide of nitrogen or ni- trous oxide. 967. Properties of Nitrous Oxide. It is a permanent gas. 100 cubic inches weigh 47.25 grains. It supports the combustion of a candle flame vividly ; though nitric oxide gas, containing twice as much oxygen, extinguishes flame. Phosphorus is difficult to inflame in it, but burns with rapidity when once on fire. The habitudes of sul- phur are in this respect analogous to those of phospho- rus. An iron wire burns in it nearly as well as in oxygen gas. Most of the combustible bodies burn in nitrous oxide. When ignited with hydrogen, an explosive reaction en- sues, and water and nitrogen result. It has no attribute of acidity. When respired it stimulates and then destroys life. Its effects on the human system, when breathed, are analogous to a transient, peculiar, various, and generally very vivacious ebriety. It is much more rapidly and ex- tensively soluble in water than oxygen. Homberg's pyro- phorus, or that which I have contrived to obtain from Prussian blue, takes fire on falling through the gas. Agreea- bly to the researches of Faraday, to the results of which allusion has been made, when nitrate of ammonia was heated at one end of a sealed recurved tube, nitrous oxide was condensed into a liquid at the other end. Experimental Illustrations. 968. The process and apparatus for producing, collect- ing, and breathing nitrous oxide gas, exhibited. The ef- fect on a lighted candle and on an iron wire, shown. Combustion of Phosphorus in Nitrous Oxide. 969. There is a singular indisposition in the oxides of nitrogen to part with their oxygen to phosphorus, until it be intensely ignited either by an incandescent iron, or by the access of uncombined oxygen. 970. This characteristic in the case of nitrous oxide, may be illustrated by means of an apparatus, like that employed for the combustion of phos- phorus in oxygen, and of which the opposite engraving is a representation. It consists of a tall cylindrical receiver, and a tube descending through the neck and along the axis of the receiver, terminating in a capillary orifice over the cup for holding the phosphorus. The upper end of the tube, out- 182 INORGANIC CHEMISTRY. side the receiver, is furnished with a cock, to which a gum-elastic bag in- flated with oxygen is attached. 971. Under these circumstances, the receiver having been exhausted and filled with nitrous oxide, phosphorus, previously placed within the cup, may 'be melted without taking fire. But as soon as the cock communicating with -the bag of oxygen is opened, an intense combustion ensues ; since the oxygen, emitted in a jet from the capillary orifice of the tube, reaches the melted phosphorus, and excites it into active combustion, which the nitrous oxide afterwards sustains with great energy. Of Nitric Oxide, formerly called Nitrous Air. 972. This oxide is an artificial product, and is obtained only in the gaseous state. Its tendency to combine with oxygen renders it impossible for it to exist where the at- mosphere has access. 973. Preparation. Nitric oxide is evolved during the reaction between nitric acid, and copper, silver, and other metals. Self-regulating Apparatus for generating Nitric Oxide. 974. The command of a sufficient supply of nitric oxide is most conveniently attained by means of a self-regulating apparatus, made in the manner which I am about to describe. 975. A vessel, perforated at the foot, in other respects resembling a decanter ; and hav- ing a long neck, surmounted by an air-tight cap, cock and gallows screw, is placed within a glass jar of suitable dimensions, as repre- sented in the adjoining figure. By means of the gallows screw, a flexible leaden pipe is so attached, as to form a communication with the bore of the cock. The cavity of the bottle being supplied with copper shreds or turnings, and the jar with diluted nitric acid, by the re- action of the metal with the acid, gas is co- piously evolved, producing red fumes by gene- rating nitrous acid with the oxygen of the air. The emission of the gas should be permitted until the red fumes disappear. The cock may then be closed, unless it be desirable to allow the gas to be transferred to another vessel. 976. It should be understood that the acid passes into and out of the bot- tle, through the perforation in the stem; while by means of a fragment of glass, the metallic shreds are prevented from escaping. 977. Properties. Nitric oxide is colourless, permanent- ly elastic, and rather heavier than air. By water it is but slightly absorbed. It is not acid. It extinguishes a can- dle flame, but ignites Homberg's pyrophorus, and supports NITROGEN. 183 the combustion of phosphorus, if inflamed before immer- sion in it, or aided by the access of a minute quantity of oxygen. It is fatal to animals, renders the flame of hydro- gen green by mixture, does not explode with it, but ex- plodes with ammonia. It unites rapidly with oxygen gas, the oxygen of the air, or of any other gaseous mixture, producing remarkable red acid furnes. v It is absorbed by the green sulphate and the protochloride of iron. The solution acquires the property of absorbing oxygen, and is therefore used in eudiometry. Nitric oxide is decomposed by moistened iron filings; also by ignited charcoal, arse- nic, zinc, and potassium. Experimental Illustrations of the Properties of Nitric Oxide. 978. Copper or silver being subjected to nitric acid, ni- tric oxide gas is extricated, and collected in bell glasses over water or mercury. 979. Absorption of nitric oxide gas by protochloride, and protosulphate, of iron, shown: also the method of ascer- taining its purity by the sliding-rod eudiometer; and its application to eudiometry, in various ways, by means of that, and other eudiometrical instruments. 980. Self-regulating reservoir of nitric oxide gas for eu- diometrical experiments. Absorption of oxygen gas by nitric oxide, and the consequent acidity, made evident by the effect on litmus. Pyrophorus in falling through the gas is ignited. Of Hyponitrous Acid. 981. This acid was isolated in the following manner by Dulong. Hav- ing subjected a mixture of four volumes of nitric oxide with one of oxygen, in a tube, to a freezing mixture, he obtained the acid in question in the form of a deep green liquid so volatile as to be converted into a red vapour, unless restrained by intense cold. The hyponitrous acid, thus procured, is partially decomposed by water into nitric oxide which escapes ; while the oxygen, combining with another portion of the hyponitrous acid, forms nitric acid. This unites with the water, and protects the remainder of the hyponitrous acid from decomposition. According to Berzelius, it is formed, in combination with bases, when nitrates are kept at a red heat for some time. It is alleged that a hyponitrite of lead is produced, when nitrate of lead is boiled with metallic lead. 982. Hyponitrous acid, when isolated, does not combine directly with bases, but is resolved by contact with them into a nitrate and nitric oxide gas. Nevertheless it may be transferred from one, base to another. It is 184 INORGANIC CHEMISTRY. alleged to form a crystalline compound with sulphuric acid, and to combine with nitric acid ; but it is questionable whether, in combining with nitric acid, it is not resolved into nitric oxide and nitric acid. As an ingredient in one of the ethereal compounds formed by the reaction of nitric acid with alcohol, this acid appears to have some practical importance. Of the ether thus formed it would be premature to treat, until the subject of etherifica- tion is undertaken. Of Nitrous Acid. 983. This combination may be procured in the gaseous state, by mix- ing two volumes of deutoxide of nitrogen, and one of oxygen; or by sub- jecting fuming nitric acid to heat, and collecting the product in a receiver. It is also procured by distilling nitrate of lead. Moist nitrous acid is a gas of a deep red colour. When anhydrous, it is a liquid of an orange-yellow which boils at 72. In this form it may be obtained by passing deutoxide of nitrogen and oxygen, both previously dried, through a tube filled with fragments of porcelain; or by desiccating the nitrate of lead before employ- ing it as above mentioned. 984. As the compound, consisting of one atom of nitrogen and four atoms of oxygen, called nitrous acid by the chemists of Great Britain, is decomposed when presented to bases, Berzelius does not regard it as a dis- tinct acid : but gives the name in question, to the trioxide of nitrogen, (756,) called hyponitrous acid by the British chemists. 985. The tall receiver and the pear-shaped vessel in its vicinity, being filled with water, and placed upon the shelf of the hydro-pneumatic cistern, (609, &c.) as repre- sented in the engraving, by means of cocks with gallows screws, and a leaden pipe, properly attached, render it practicable to make between them a communication at pleasure. 986. These preparations being made, allow the pear-shaped vessel, which I will call a volumeter, to be twice filled with nitric oxide, and as often allowed to yield up its contents to the receiver. Then fill the volumeter with oxygen gas. In the next place, open the communication again with the receiver. The oxygen, passing into the nitric oxide, produces dense fumes of nitrous acid. At first, in consequence of the rise of temperature which attends the combination, there appears some expan- sion; but a speedy absorption of the nitrous acid generated, causes the water to rise, and nearly fill the receiver. From some hidden cause, I have never been able to attain a complete condensation by this process, however pure might be the gaseous materials employed. Application of Nitric Oxide Gas to Eudiometry. 987. The property which this substance has of forming with oxygen, nitrous or hyponitrous acid, either of which is absorbed by water, has caused it to be used in eudiornetrical operations; but owing to the variable proportions in which the above- mentioned compounds are liable to be formed, the results obtained have been deemed uncertain, and the directions for using nitrous oxide, given by such emi- nent chemists as Dalton, Gay-Lussac, and Thomson, are at variance. Gay-Lussac gave an empirical formula, agreeably to which one-fourth of the condensation, pro- duced by a mixture of equal parts of atmospheric air and nitric oxide, is to be as- sumed as the atmospheric oxygen present. 988. As in two volumes of nitric oxide, a volume of nitrogen is combined with one volume of oxygen, occupying the same bulk as if merely mingled, to convert the nitric oxide into nitrous acid, which consists of the same quantity of nitrogen with two volumes of oxygen, one volume of oxygen must be added. Of course, if nitrous acid be the product, one-third of the deficit produced, would be the quantity of atmospheric oxygen present. This would be too much to correspond with the formula of Gay-Lussac. 989. Supposing hyponitrous acid produced, only half as much oxygen would be required as is necessary to produce nitrous acid; so that instead of the two volumes of nitric oxide taking one volume, they would take only half a volume. The ratio of | in 2.J, is the same as I in 5, or one-fifth, which is too little for Gay-Lussac's rule. 900. The formula recommended by Dr. Thomson, agreeably to which one-third of Synthesis of Nitrous Acid. (Page 184.) Volumescopefor the Analysis of Atmospheric Air by Nitric Oxide. (Page 185.) NITROGEN. 185 the deficit is to be ascribed to oxygen, is perfectly consistent with the theory of vo- lumes, and much more consonant with the results of my experiments than that re- commended by the celebrated author of that admirable theory. !>!>!. The late Professor Dana ingeniously reconciled Gay-Lussac's statement with the theory of volumes, by suggesting that half a volume of oxygen may take one volume of the nitric oxide, and another half volume of oxygen, two volumes. vol. vol. J oxygen takes 1 oxide and forms nitrous acid. oxygen 2 oxide and forms hyponitrous acid. 1 3 992. The total condensation here would be four volumes, and the deficit due to oxygen is one volume, or one-fourth. 993. With the deference due to a chemist so distinguished as the author of the formula in question, 1 long strove unsuccessfully to verify his statements. Agreeably to a great number of experiments, annually repeated during many years with differ- ent instruments, it has been found that, when three volumes of nitric oxide are mix- ed, over water, with five of atmospheric air, nearly the same condensation is effected, as when like quantities of air and hydrogen are ignited together. In order to de- monstrate the truth of this allegation to my numerous class of pupils, I have em- ployed the apparatus represented by the opposite engraving, and described in the following article. In this the volumes employed are so large as to make the results strikingly evident to the most remote observer. Volumescope for the Analysis of Atmospheric Mr by Nitric Oxide. 994. Secured in a screw rod and plate frame, (248,) there is a glass cylinder thirty inches in height, and about five inches in diameter. Into the brass plate which closes it at top, three cocks are inserted, each provided with a gallows screw. By means of a flexible leaden pipe, let one of the cocks be make to communicate with an air pump. Let the other cock, by like means, be made to communicate with a pear-shaped glass vessel, which acts as a volumeter, or volume measurer. Let the cylinder, by means of scales placed on each side of it, be graduated so as to hold eight volumes, any three of which shall be equivalent, collectively, to the contents of the volumeter. The apparatus being thus prepared, and secured over one of the wells of the pneumatic cistern, (613 ,) exhaust the cylinder by means of the air pump, so as to cause the water to rise in it, until by the scale only five volumes of atmos- pheric air are left, and then open a communication with the volumeter. The air contained in this vessel will then pass into the cylinder, consequently the water will subside to the division upon the scale which designates eight volumes, thus showing that the capacity of the volumeter is equivalent to three volumes as premised. Next, by means of the pump, raise the water again to the division upon the scale, marking five volumes, and fill the volumeter with nitric oxide. If, under these circumstances, the communication between the pear-shaped vessel and the cylinder be re-established, the nitric oxide will pass into the cylinder, and, combining with the oxygen of the contained air, will produce nitrous acid in red fumes, which the water will absorb rapidly at first. This absorption is promoted and completed by jets of water, pro- jected vertically through the mingled gases, by means of the recurved pipe, and gum elastic bag to which it is attached. It has been shown by the preceding part of the process, that the contents of the volumeter, added to five of air, would make eight volumes, were there no absorption; but the actual residue, when the experi- ment is well performed, is always a little less than five volumes, indicating that a little more than one volume of oxygen is contained in the five volumes of air em- ployed, and that this is condensed by combining with twice its bulk of nitric oxide. The nitrous acid, usually thus called, consists of one volume of nitrogen and two volumes of oxygen. Of course, to convert into this acid, nitric oxide, consisting of one volume of nitrogen and one volume of oxygen uncondensed, one volume of oxygen must be added. Aqueous Sliding-rod Eudiometer for the Analysis of Gaseous Mixtures by Absorption. 995. The form of the sliding-rod eudiometer represented in the next figure does not differ from that for inflammable mixtures, (940,) as respects the mechanism by which the rod is secured, or the graduation, which it is convenient to have exactly alike in both. The modification "which I am about to consider I found very ser- viceable in the analysis of gaseous mixtures, containing carbonic acid gas. or for 24 186 INORGANIC CHEMISTRY. ascertaining the purity of nitric oxide gas by the aid of protosulphate of iron. It may also be applied to the analysis of the atmosphere by nitric oxide, agreeably to the process which I shall forthwith describe. 996. The receiver, represented in the following cut, shaped like the small end of an egg, is employed in these experiments, being mounted so as to slide up and down upon a wire. 997. Being filled with water, and immersed in the pneumatic cistern, the apex, A, being just even with the surface of the water, by drawing out the rod of the eudiometer, take into the tube 100 measures of atmospheric air, and transfer it to the receiver. Next take 50 measures of nitric oxide from a bell as above described, and add it to the air in the receiver. Wash the mixture by a jet of water, which is easily produced from the apex of the instrument, and draw the whole of the residual gas into the tube, continuing to draw out the rod until 150 graduations appear. In the next place, eject the residual gas from the instrument: the number of graduations of the rod which remain on the outside of the tube, shows the deficit produced by the absorption of the oxygen and nitric oxide, in the state of nitrous acid. 998. In a great number of experiments, I have found the deficit to agree very nearly with that produced by the explosion of the same quantity of air with hydro- gen, in the aqueous sliding-rod hydro-oxygen eudiometer; but upon the whole it is rather greater. Method of ascertaining the Purity of Nitric Oxide by means of a Solution of Protochlo- ride, or Protosulphate of Iron. 999. The purity of nitric oxide is easily ascertained by means of a solution of protochloride, or green sulphate of iron, and the sliding-rod eudiometer above de- scribed. A small bottle being filled with a solution of the salt, and inverted upon the shelf of the hydro-pneumatic cistern, take into the eudiometer one hundred mea- sures of the gas, and transfer them to the bottle, which must be agitated for two or three minutes. The receiver, being filled with water, and depressed into the water of the hydro-pneumatic cistern, till the apex, A, is on a level with the surface, throw up into it the residual gas. In the next place, draw it into the eudiometer. 1000. In doing this it is immaterial how much water may follow, because the quantity will be inferred from the number of graduations, which must enter the cavity of the tube, in order to effect the expulsion. Of course the impurity will be as the number thus found. NITROGEN. 187 1001. A saturated solution of nitric oxide in the abovementioned ferruginous solu- tions, has the power of absorbing oxygen, and was recommended by Sir H. Davy as the means of ascertaining the quantity of that gas in the air. The mode of using them would be the same as that just described, taking oxygen into the eudiometer instead of nitric oxide, and filling the bottle with the ferruginous solution of nitric oxide, instead of the solution of the pure sulphate or protochloride of iron. I have found this method of ascertaining the quantity of oxygen in the air, much more te- dious and much less satisfactory than those already described. Theory of Volumes. 1002. It is presumed that a reader, who has carefully studied this work thus far, may have his attention advan- tageously directed to the theory of volumes; otherwise the language, now usually employed in treating of combi- nations resulting from the union of gaseous substances, would not always be intelligible to him. 1003. It has been advanced by Gay-Lussac, that sub- stances, when aeriform, unite in volumes which are equal, or that when unequal, the larger volume is double, triple, or quadruple the other. 1004. This hypothesis has been verified by experiment with respect to all substances which are capable, while gaseous, of being combined or decomposed. It is extended by inference to other substances, under the idea that all are susceptible of the aeriform state. A volume is said to be the equivalent of another volume, when capable of forming with it a definite compound, or when just ade- quate to displace it from combination. 1005. It must be evident, a priori, that if each atom, of whatever kind, were to occupy in the aeriform state an equal space, atoms might be as well represented by equal volumes as by their equivalent numbers; the former af- fording by measure, what the latter give by weight. Now experience justifies the belief that, in general, atoms do assume an equality of volume when rendered aeriform, and that, when the bulks assumed are unequal, the inequality may be removed by multiplying or dividing, by a whole number, those volumes which are smaller or larger than the rest. This is all that the hypothesis of Gay-Lussac requires. 1006. Berzelius infers that water, and the protoxides of chlorine and nitrogen, each consist of one atom of oxygen, and two atoms of the other ingredient. Admitting this to be a correct inference, equivalent weights of the four ele- mentary gaseous substances abovementioned, actually oc- 188 INORGANIC CHEMISTRY. cupy equal spaces; so that their atoms are as well repre- sented by equal volumes, as by the numbers indicating their ratio to each other in weight. But if we suppose that, in the compounds abovementioned, there is only one atom of each ingredient, the equivalent volumes of chlo- rine, hydrogen, and nitrogen, although still equal to each other in bulk, will each be twice as large as the equivalent volume of oxygen. The British chemists, in general, pre- ferring the last mentioned view of the atomic constitution of the compounds abovementioned, represent the atoms of chlorine, hydrogen, and nitrogen, each by one volume, the atom of oxygen by half a volume. 1007. When gaseous substances enter into combination preserving the aeriform state, in some cases there is a re- duction of volume, in others none. When a reduction does ensue, the bulk, or resulting volume of the compound, is to the aggregate bulk of the constituent volumes, either as 1 to 2, 1 to 3, 1 to 4, or 2 to 3, 2 to 5, &c. 1008. This will be rendered evident by the following table, in which the number of atoms and the number of volumes which enter into some important compounds, are represented by corresponding squares. Each square stands for a volume, and half a square for half a volume. The first column contains the name of each gas or va- pour; the second, the equivalent volume of the gas if sim- ple, or an association of the volumes representing its constituents if compound; the third, the resulting volume of the compound formed; and the last, the pressure, ex- pressed in atmospheres, necessary to produce liquefaction. 1009. Among the instances cited in the table, it will be seen that there is none in which the bulk of the consti- tuent volumes is to that of the resulting volume in a ratio greater than that of 3 to 1. The only permanent gas, in which the elements are alleged to exist in a state of greater condensation, is olefiant gas, consisting of two volumes of the vapour of carbon, and two volumes of hy- drogen, condensed into one volume. There are some vapours, consisting of the same elements in the same atomic proportion, in which 8 or 9, or, according to Dr. Thomson, even 25 constituent volumes are contained in 1 resulting volume. NITROGEN. 189 Table of the Equivalent Weights and Volumes of some Gases and Vapours. Gases and Vapours. Oxygen . . Chlorine . . Protoxide of chlo- rine . Hydrogen . . . Steam . . . . Chlorohydric acid Nitrogen . . . . Atmospheric air . Nitrous oxide . . Nitric oxide . . Nitrous acid Ammonia Component Volumes. 08 Cl 3(3 Cl 36 08 C 36 08 N 14 N 14 08 O8 O8 O 08 08 O8 H 1 H 1 N H 14 1 lesulting Volumes of Compounds. 37 46 Pressure of Liquefaction Atmospheres. 4 at 00 40 at 50 50 at 45 at 50 190 INORGANIC CHEMISTRY. Of Nitric Acid. 1010. Although, under ordinary circumstances, nitrogen will not combine with oxygen; yet, when mixed with it, and exposed to a succession of electric sparks, nitric acid, one of the most important agents in chemistry, is genera- ted. Berzelius alleges that traces of nitric acid, in combi- nation with ammonia, may almost always be discovered in the rain water accompanying thunder storms. This chemi- cal combination is probably produced by lightning. The same author states that when a jet, consisting of one vo- lume of nitrogen and fourteen of hydrogen, is inflamed while flowing into a vessel containing oxygen, nitric acid is produced. There are probably some unknown means, by which chemical union is induced between nitrogen and oxygen; whence the great quantity of nitrate of potash spontaneously produced, in various situations. 1011. It has been supposed that this acid is formed during the eudiometrical analysis of atmospheric air by hydrogen; and that the deficit being thus increased, leads to an undue estimate of the oxygen. I consider this im- pression erroneous; as upon one occasion, by exploding successive portions of hydrogen with atmospheric air, I collected nearly half an ounce of water, and found it devoid of acidity. 1012. Preparation. The production of nitric acid by electricity is too laborious to be resorted to for the purpose of the chemist. 1013. Agreeably to the usual process, nitre, which con- sists of nitric acid and potash, is subjected to heat with an equal weight of sulphuric acid, in a glass, porcelain, or iron retort, communicating with a glass receiver. The nitric acid is displaced by the superior affinity of the sulphuric acid for the potash, and, being vaporized by the heat, passes into the receiver, where it condenses into a liquid. Thus obtained, it is more or less contaminated with nitrous acid or nitric oxide, also with chlorohydric, and sulphuric acid. By distilling from it about a third of the whole quantity, the nitrous and chlorohydric acids pass over into the receiver with the portion of nitric acid distilled, leaving the residue in the retort free from them. Sulphuric acid may be removed by distilling the nitric acid from one- eighth of its weight of pure nitre, or by the addition of ba- NITROGEN. 191 ryta, which precipitates in the, form of an insoluble corn- pound with the sulphuric acid. Chlorohydric acid may in like manner be removed by a solution of silver; as this metal forms with the chlorine an insoluble compound which precipitates. 1014. Properties. Nitric acid emits pungent suffocating fumes, and has a peculiar odour. When pure it is colour- less, but when exposed to the light, it is slowly decom- posed into oxygen gas, and nitrous acid or nitric oxide which is absorbed, giving an orange colour to the nitric acid. This decomposition takes place much more rapidly in the sun. Nitric acid cannot be obtained free from wa- ter. With almost all the metals it reacts powerfully, also with organic substances, causing them to be oxidized. It stains and destroys the skin. It may be considered as consisting of the ingredients of atmospheric air in the liquid form, but containing ten times as much of the active prin- ciple, oxygen. It is the most energetic principle in gun- powder. In its highest state of concentration, at a speci- fic gravity of 1 .55, one atom of the acid contains one a torn of water. This concentrated acid boils at 175 and freezes at 40. When it contains one atom of acid to four of water, it has a specific gravity of 1.42, and boils at 248. Any acid, whether weaker or stronger than this, has the boiling point at a lower temperature. If weaker it is strengthened, if stronger it is weakened, by boiling; and acids of all degrees of strength become, by the continued application of a sufficient degree of heat, of the specific gravity of 1.42. The officinal specific gravity is 1.5, in which case it contains two atoms of water to one of acid. 1015. Nitric acid is employed in giving a yellow colour, and for various other puposes in manufactures. It is used in medicine for fumigations, in cases in which chlorine is unsuitable. Experimental Illustrations. 1016. The extrication and distillation of nitric acid, shown by means of a glass retort and receiver, heated by a lamp or small sand bath. Its action on various sub- stances exemplified. 192 INORGANIC CHEMISTRY. Of the Orange-coloured Fuming Nitric Acid, called Nitroso- nitric Acid in the Swedish Pharmacopoeia. 1017. In whatever proportion sulphuric acid may be em- ployed in the process just described for procuring nitric acid, the liquid obtained is of an orange colour. This co- lour becomes deeper, when the quantity of sulphuric acid employed is insufficient to produce a bisulphate with the potash. I am under the impression that, in some degree, the same result follows when the acid exceeds the propor- tion requisite to produce the bisulphate. In either case the water, which in the absence of some other base is indispen- sable to the existence of nitric acid, is not furnished in sufficient quantity. Hence the acid is partially resolved into oxygen and nitrous acid, which latter, together with the nitric acid, passes into the receiver, constituting an orange-coloured fuming liquid, mentioned by Berzelius under the name of nitroso-nitric acid. This acid, by expo- sure to heat, disengages nitrous acid gas, and becomes co- lourless nitric acid. Nitroso-nitric acid ignites essential oils, carbon, and phosphorus; the latter explosively. It is much more energetic in its reaction with such substances than pure nitric acid, which, probably, when nitric oxide is not present, requires for its existence a larger proportion of water. I deem it probable that it is with nitric oxide, not nitrous or hyponitrous acid, that nitric acid is com- bined in nitroso-nitric acid. Berzelius conceives that either view of its composition may be correct. Experimental Illustrations. 1018. Reaction of nitroso-nitric acid with carbon and oil of turpentine, exhibited, also with caoutchouc tar. Of the Agency of Nitric Oxide in generating Sulphuric Acid. 1019. When nitric oxide, atmospheric air, sulphurous acid, and aqueous vapour are mingled, a crystalline compound is formed, which, if the ope- ration be performed within a glass vessel, will appear upon the interior sur- face in a crystalline deposition, resembling hoar frost. When water is added to this compound, it is resolved into sulphuric acid and nitric oxide. The former combines with the water, while the latter escapes in the gaseous form, producing with oxygen, if present, the red fumes of nitrous, or hypo- nitrous acid. It may be inferred that hyponitrous acid, produced as above mentioned, yields one atom of oxygen to the sulphurous acid, converting it into sulphuric acid. The acid, thus produced, unites with the nitric oxide NITROGEN. 193 and water ; but on being subjected to a larger portion of water, for which it has a greater affinity, the nitric oxide is allowed to escape. These habi- tudes of the agents in question excite greater interest, on account of their agency in the generation of sulphuric acid, one of the most valuable of the instruments which have been placed within the reach of the chemist, artist and manufacturer. Experimental Illustration of the Reactions which occur in the Manufacture of Sulphuric Acid. 1020. Into a glass globe with three tubulures, insert through one of them, the beak of a pint retort, containing about a pound of mercury, and as much sulphuric acid as will cover it to the depth of half an inch, applying to the retort a chauffer of coals. Into the other tubulure, fasten the termi- nation of a pipe proceeding from a self-regulating reservoir of nitric oxide gas. The third tubulure should be closed by a glass stopple. The mercury takes one atom of oxygen from the sulphuric acid, converting it into sul- phurous acid which enters the globe. As soon as this appears to have taken place, a portion of the nitric oxide gas is allowed to enter from the opposite side. Meeting with atmospheric air within the vessel, the nitric oxide will produce red fumes, which, encountering the sulphurous acid, will condense into a crystalline deposition. Occasionally, the stopple must be lifted to allow the access of fresh air ; and the supply of this and the gases must be so regulated, that the red fumes shall be repeatedly produced and con- densed. When a deposition of crystalline matter, sufficiently striking, has been produced, if water be poured into the globe, the deposition will be speedily decomposed with an evolution of nitric oxide. This gas, meeting with the oxygen of the air, produces red fumes, which, by the readmission of sulphurous acid, are again condensed with it into crystals. These crys- tals, as before, by the addition of water, are decomposed into nitric oxide gas and sulphuric acid. The water in the globe, being decanted and tested, gives decided indications of the presence of sulphuric acid. 1021. Latterly, the process above described, has been resorted to in the large way in the manufacture of sulphuric acid. In some cases the nitric oxide has been evolved by the reaction of nitric acid with organic substances of a nature to produce oxalic acid, but in other manufactories the nitric oxide is obtained from nitric acid by subjecting it to sulphuric acid, which causes it to be resolved into nitrous or hyponitrous acid fumes and oxygen gas. 1022. When nitric oxide is obtained by the reaction of nitric acid with sugar or molasses, oxalic acid is produced, and tends to defray, partially, the expense of the process. Of the Process usually employed in the Manufacture of Sulphuric Acid. 1023. The combustion of one portion of sulphur, and the simultaneous deflagra- tion with nitre of another portion, (the fumes created in both ways being received in a large chamber lined with lead, and covered at bottom with water) are the means usually employed for the manufacture of sulphuric acid. Each atom of nitre con. sists of an atom of potash and an atom of nitric acid. Three out of the five atoms of oxygen in each atom of the acid, unite with an atom of sulphur, converting it into sulphuric acid, which combines with the potash. The two remaining atoms of oxy- gen, together with the -nitrogen of the acid, are evolved as nitric oxide, which, with atmospheric oxygen, moisture, and the sulphurous acid produced by the burning sulphur, generates the crystalline compound above described. Of late years, the presence of an adequate quantity of moisture has been insured by the introduction 25 194 INORGANIC CHEMISTRY. of steam at proper intervals. The crystalline compound, subsiding into the water, is decomposed into sulphuric acid, which remains in solution, and nitric oxide. This oxide, meeting with further portions of oxygen and sulphurous acid, again contri- butes to the formation of the crystalline compound, to be again decomposed. This process is continued until the water in the chamber becomes sufficiently impregnated with sulphuric acid, when it is transferred to leaden boilers. In these it is concen- trated by boiling, but it is removed before it attains sufficient strength to attack the lead, to a platinum alembic, or to glass retorts, and boiled down to the specific gra- vity of 1.85. After it has reached that density, no farther concentration can be ef- fected by heat. This, accordingly, is the standard specific gravity of the sulphuric acid of commerce. Production of Sulphuric Add, further illustrated. 1024. The apparatus here described, serves to show, in miniature, the process for generating sulphuric acid. 1025. Provide a globular glass vessel with a wide mouth fitted to a suitable cover, and capable of holding at least eight gallons, represented by the preceding figure. Through a hole in the centre of this plate, a gun barrel, open at both extremities, is made to descend. From the lower extremity, a ring of about two inches in diame- ter is suspended by wires, hooked to a perforated circular piece of sheet metal, which encircles and is soldered to the barrel. In the ring thus suspended, a conical frus- tum of iron, having an hemispherical cavity, is seated, so as to be a little above the water. Between the outside of the gun barrel, and the inside of the brass casting, C, which supports it. there is a passage from the pipe, P, into the cavity of the globe. This pipe communicates also with the water of a tumbler, supported within the bell glass. A tube leads from a suction pump into this vessel, which is placed on the shelf of the pneumatic cistern, covered with water as usual. 1026. The apparatus being thus arranged, the metallic plate, with the gun barrel, ring, and frustum appended to it, must be removed from the globe, the iron frustum lifted out of the ring, and some nitrate of potash (nitre) being introduced into the cavity in the frustum, it must be made moderately red-hot. It is then to be restored to its seat in the ring, below the gun barrel, and the plate and gun barrel must be returned to their previous position over the mouth of the globe, so that the whole may be situated as represented in the engraving. Lumps of brimstone, about the size of peas, are to be dropped through the gun barrel into the melted nitre. As each lump reaches the nitre a combustion ensues, equally remarkable for beauty and brilliancy. The globe then becomes filled with sulphurous acid gas, accompanied by nitric oxide gas, and a crystalline deposition ensues. Meanwhile, to keep up a supply of oxygen within the globe, and to prevent the escape of fumes into the apartment, the suction pump is put into operation, in order to draw the fumes out of the globe, and cause them to be replaced by air, which enters through the gun bar- NITROGEN. 195 rel. The water rises from the cistern into the bell, until the resistance which it offers to further elevation, is greater than that which the water, in the tumbler on the stand, opposes to the entrance of air from the pipe; and, consequently, the air is drawn from the globe through the water in the tumbler, by which the fumes arising from the combustion are arrested, especially if liquid ammonia shall have been pre- viously added to the water. 1027. To protect the globe from the heat of the red-hot iron frustum, a cylinder of sheet lead is placed below it, as represented in the figure. 1028. The fumes generated during this process, condense upon the inner surface of the globe, into a white crystalline compound, identical with that procured in the process above described. By the affusion of water, this crystalline matter undergoes a decomposition like that already described, (1020,) giving out nitric oxide, and yield- ing sulphuric acid to the water. COMPOUNDS OF NITROGEN WITH CHLORINE AND IODINE. 1029. Neither chlorine nor iodine combines directly with nitrogen; but both unite with the nitrogen of ammonia, under circumstances which I shall mention presently. Of Chloride of Nitrogen. 1030. This compound may be obtained by placing a bell glass, filled with chlorine, over a solution of one part of nitrate of ammonia in twelve of water, at the temperature of 70. The chloride appears in drops, which resemble olive oil, and which, being heavier than water, subside to the bot- tom of the basin containing the solution. It is remarkable that this sub- stance does not explode with many combustibles, which would appear more likely to decompose it than those with which it does explode. Thus it ex- plodes with turpentine or caoutchouc, but not with camphor. 1031. The force with which a minute portion of chloride of nitrogen ex- plodes, on contact with oil of turpentine, would hardly be credited by those who have not witnessed this phenomenon. An open saucer of Canton china was fractured by a globule not larger than a grain of mustard seed. The glass tube employed to project the globule into the saucer, was violent- ly dispersed in fragments. Of Iodide of Nitrogen. 1032. When iodine is kept in liquid ammonia, it is converted into a brownish-black substance, which is iodide of nitrogen, and which may be collected and dried on bibulous paper at a gentle heat. The iodide of nitrogen thus formed, evaporates spontaneously. It explodes by a slight pressure, or when heated or much dried, being resolved into nitrogen gas and iodine. ON SOME POINTS OF CHEMICAL THEORY. 1033. The student has now advanced sufficiently far in practical know- ledge of the phenomena of combustion, and of the properties of some acids, to render it expedient to present to him some general views of combustion, acidity, and alkalinity, arid additional instruction on classification and nomenclature. I am the more inclined to this course, as, among the com- pounds of nitrogen, there are three acids and an alkali. 196 INORGANIC CHEMISTRY. Of Theories of Combustion. 1034. Stahl supposed the existence, in all combustibles, of a common principle of inflammability, which he called phlogiston, from pAyf>, to burn. He inferred that all substances, in burning, gave out phlogiston. The fallacy of this hypothesis is evident; since metals become heavier du- ring combustion, obviously in consequence of the absorption of oxygen from the atmosphere. By the advocates of the phlogistic theory, nitrogen was confounded with carbonic acid, and carbon with hydrogen, because both carbon and hydrogen were conceived to consist of phlogiston nearly pure ; and oxygen, in combining with them, was supposed to become phlogisti- cated air, the name then given to nitrogen gas. It is now well known that with carbon, oxygen forms carbonic acid, with hydrogen water; and that nitrogen gas contains neither carbon nor hydrogen. 1035. Sulphuric, and phosphoric, acid, and metallic oxides, were seve- rally supposed to be ingredients in the sulphur, phosphorus, and metals producing them. Thus of two bodies, that which was actually the lighter was assumed to contain the other. 1036. The celebrated Lavoisier, to whom we are chiefly indebted for the exposure of these fallacies of the theory of phlogiston, having ascertained that oxygen is an indispensable agent in all ordinary cases of combustion, was erroneously led to infer that it was in all cases necessary to that pro- cess. But it is now well known that there are many instances of combus- tion, in which oxygen has no agency. 1037. I would define combustion to be a state of intense corpuscular re- action, accompanied by an evolution of heat and light. 1038. That increase or diminution of temperature consequent to chemi- cal combination, which constitutes combustion when productive of heat and light, has been ascribed to a mysterious law, by which bodies undergo a change in their capacity to hold caloric. It has been supposed that the ca- pacity of the compound is in some instances greater, in others less, than the mean capacity of the constituents; and that in the former case union is 'followed by an absorption of caloric, and of course by cold; in the latter, by the expulsion of caloric, and, consequently, the production of heat. Yet, when the capacities of compounds are compared with those of their in- gredients, the result does not justify the idea that the heat given out by the latter in combining, is produced by a diminution of capacity. At best, this hypothesis only substitutes one enigma for another; since it does not ac- count for the alleged change of capacity. 1039. The diversity of power to hold caloric in a latent state, technically designated by the word capacity, is now generally ascribed to the interven- ing influence of electricity. It has been shown* that, if neighbouring bo- dies be electrified by means either of glass or resin, previously subjected to friction, they will repel each other ; but that if one be thus excited by glass, and another by resin, attraction between them will ensue. Hence the ex- citements are considered of an opposite nature. It will be recollected that, according to the Franklinian theory, the vitreous excitement results from a redundancy; the resinous, from a deficiency of the electrical fluid. The former being designated as positive, the latter as negative electricity. Agree- ably to the doctrine of Dufay, the different electric excitements are consi- dered as the effects of two different fluids, attractive of each other, but self- * See my Treatise on Statical Electricity. NITROGEN. 197 repellent. The one has accordingly been called resinous, the other vitreous electricity. Yet, even by electricians, who suppose the existence of two fluids, the terms positive and negative are employed. 1040. It has been suggested that Voltaic phenomena, combustion, acidity, alkalinity, and chemical affinity, may owe their existence to the principle by which the different electric excitements are sustained in electrified bodies, modified in some inexplicable manner, so as to act between atoms instead of masses. This suggestion derives strength from the following facts, which have been fully illustrated in my lectures on electricity and galvanism. 1041. The pole of a Voltaic series, terminated by the more oxidizable metal, has been shown to display a feeble electrical excitement, of the same kind as that which is producible by friction in glass ; while the other pole displays the opposite excitement, in like manner producible in resin. From reiterated experimental observation it is now generally inferred, that, of any two elementary atoms, chemically combined, and simultaneously exposed, to the voltaic current, one will go to the positive, the other to the negative pole. Atoms are supposed to have electrical states the opposite of those of the poles at which they may be liberated, and are said to be electro-negative when liberated at the positive pole, or anode ; electro-positive when liberated at the negative pole, or cathode. See my Treatise on Galvanism, page 7. 1042. Substances which have opposite relations to the Voltaic poles, have an affinity for each other, which is usually stronger in proportion as the diversity of their electric habitudes is the more marked. Thus, for in- stance, oxygen, which is pre-eminently electro-negative, and potassium which is pre-eminently electro-positive, have, under ordinary circumstances, a pre- dominant affinity for each other. 1043. On all sides it must be admitted that between chemical reaction, galvanism, and electro-magnetism, there is an intimate association which must be explained before the phenomena of chemical reaction can be well understood.* 1044. It has been mentioned that, of known bodies, oxygen appears to be the most electro-negative. It is questionable whether the grade next to oxygen, in the electro-negative scale, is to be assigned to chlorine or fluorine. After these follow bromine, iodine, sulphur, selenium, and tellurium. 1045. Among the metals we have a series of substances, varying from those in which the electro-positive power is pre-eminently great, as in potas- sium, sodium, lithium, barium, calcium, magnesium, &c., to such metals as belong rather to the electro-negative class. Hence, setting out from the extreme abovementioned, we may proceed through a long range of metals less and less electro-positive, till we arrive at such as produce electro- negative combinations with oxygen or chlorine, or both. More or less within this predicament, I think we find tin, mercury, gold, platinum, palla- dium, antimony, arsenic, molybdenum, and lastly tellurium. Thus at an intermediate point between the extremes at which oxygen and the alkalifi- able metals are placed, there are substances whose relation to the Voltaic poles is equivocal or wavering; and it should be understood that this relation is always comparative. Chlorine is electro-positive with oxygen and per- haps fluorine, and electro-negative with every other body. Iodine is electro- positive with oxygen, chlorine, bromine, and probably fluorine, while with other substances it is electro-negative. * See my " Treatise on Galvanism, or Voltaic Electricity, for Effects of Galvanic or Voltaic Circuits," page 19. And for Theory of the same, page 35. 198 INORGANIC CHEMISTRY. 1046. Substances of the two opposite classes, in combining with each other, constitute compounds which are either electro-positive or electro- negative, accordingly as the different energies of their ingredients prepon- derate. Thus in alkalies, consisting of oxygen united with the alkalifiable metals, the electro-positive influence predominates ; while the reverse is true of acids, consisting of the same electro-negative principle, oxygen, in com- bination with sulphur, nitrogen, phosphorus, carbon, boron, silicon, sele- nium, or other substances, which, in their electrical habitudes, lie between oxygen and those metals. 1047. In some cases we see an electro-negative or electro-positive power attached to compounds, which is not equally displayed by either of their constituent elements separately. Cyanogen, consisting of carbon and ni- trogen, is a striking instance of an electro-negative compound thus consti- tuted; and in ammonia, and the vegetable alkalies lately discovered, we have instances of electro-positive compounds, produced from principles com- paratively electro-negative. 1048. For any further view of the connexion between chemical and galvanic reaction, I refer to my Treatise on Galvanism, or Voltaic Electri- city, especially to pages 7, 17, 35. Of the Influence on Classification and Nomenclature of the Habitudes of Chemical Agents with the Voltaic Series. 1049. It would follow from the statements made under the last head, that there should be a resemblance between the properties of substances which have a proximity to each other in the electric series. (1042.) Ac- cordingly we find, that those which occupy the higher part of the electro- negative scale, have, by distinguished writers, especially in Great Britain, been classed as supporters ; while those which are electro-positive, or feebly electro-negative, have been by the same authors classed as combustibles. Also, certain electro-negative compounds, formed of the pre-eminently electro-negative principles, have been associated as acids; while other com- pounds, of oxygen at least, which have the opposite polarity, have been associated as bases, under some of the subordinate divisions of alkalies, alkaline earths, earths proper, or simply oxides. 1050. The idea of a class of supporters of combustion, and of combustibles, has no better foundation than that certain substances are the most frequent agents in combustion. Thus hydrogen will produce fire with oxygen and chlorine only ; sulphur with oxygen, chlorine, and the metals ; and car- bon with oxygen ; but as either oxygen or chlorine will burn with a greater variety of substances, they have been called supporters of combustion, and the substances with which they combine during combustion, combustibles. Iodine and latterly bromine have been classed among the supporters ; be- cause they combine with almost all the bodies with which the other ele- ments classed under that name unite, and in some cases with an evolution of heat and light. Yet they are not gaseous like oxygen and chlorine, and are as analogous to sulphur as to oxygen. There appears to me to be an error in taking either of these substances into the class of supporters, while sulphur is excluded, which, next to oxygen and chlorine, has the property of burning with the greatest number of substances. In other respects sul- phur seems, in its properties, to be intermediate between iodine and phos- phorus. The habitudes of selenium appear to range between those of tel- lurium and sulphur. 1051. Hydrogen, phosphorus, carbon, boron, and silicon are no more en- NITROGEN. 199 titled to be called combustibles, than oxygen, chlorine, bromine, and iodine, &c. to be called supporters. It should be observed, also, that these appella- tions are evidently commutable according to circumstances; since a jet of oxygen, fired in hydrogen, is productive of a flame, similar to the inflamed jet of hydrogen in oxygen. If we breathed in an atmosphere of hydrogen, oxygen would be considered as inflammable, and of course a combustible. The arrangement which I have adopted of classifying as basacigen bodies, those which have heretofore been treated as supporters, with the addition of some others, renders it unnecessary to resort to the incorrect division into supporters and combustibles. Method of distinguishing Degrees of Oxidizement, derived from the School of Lavoisier. 1052. The method which, in concurrence with Thenard, I have pur- sued in designating in the case of the compounds formed by the basacigen bodies with radicals, the proportion of the former ingredient has been stated. (756.) 1053. In the case of oxacids another method was adopted by the Lavoi- sierian school, which, with some modification, still endures, and which I shall state as it now prevails. 1054. Agreeably to the nomenclature in question, where, in consequence of different degrees of oxidizement, substances form two acids, one con- taining a larger, the other a lesser proportion of oxygen, the acid, having the lesser proportion, is distinguished by the name of the substance oxy- genated, and a termination in ous ; that containing the larger proportion of oxygen is designated in the same way, substituting ic for ous; as sulphur- ous acid and sulphuric acid. That ingredient in an acid or a base, which is least electro-negative, is called the radical. When an acid is discovered having less oxygen than one with the same radical, of which the name ends with ous, the word hypo is prefixed. Hence the appellations, hypo- nitrous, %posulphurous. The same mean of distinction is employed to designate a degree of oxygenation exceeding that designated by ous, but less than that designated by ic. Hence the name %posulphuric. If there be an acid having still more oxygen than the one of which the name ends in ic, the letters oxy are prefixed. 1055. Acids of which the names terminate in ous, have their salts dis- tinguished by a termination in ite. Acids of which the names end in ic, have their salts distinguished by a termination in ate. Thus we have nitrites and nitrates, sulphites and sulphates. If the base be in excess, the word sub is prefixed, as sw&sulphate. If the acid be in excess, super is prefixed, as swpersulphate. The letters bi are placed before the name of salts having a double proportion of acid ; hence carbonate and Bicarbonate. 1056. The oxide in which the oxidizement is supposed to be at the maximum is called the peroxide. This monosyllable, per, is also used in the case of acids, to signify the highest state of oxygenation, and has been (859) substituted for oxy in the case of perchloric acid. Many chemists ap- ply the monosyllable in question to distinguish a salt formed with a perox- ide. Thus the red sulphate of iron has been called the persulphate of iron. The nitrate of the red oxide of mercury, the pernitrate of mercury. Agree- ably to a similar rule, salts formed with protoxides have the word proto prefixed ; as in the instances of proton itrate, pro^osulphate, &c. 1057. It has already boon st.-itod that by the British chemists the binary- compounds of oxygen, chlorine, bromine, iodine, fluorine, and cyanogen, when not acid, are designated by the termination in ide. 200 INORGANIC CHEMISTRY. 1058. The word oxide has been erroneously used as a correlative of the word acid, instead of being used as a generic name for any compound of oxygen, whether an acid or base. I should deem it preferable to apply the termination in ide> to all compounds of the basacigen bodies, Whether acids, bases or neutral, employing the words acid and base as terminations to in- dicate the subordinate electro-negative, and electro-positive compounds. In that case oxybase, chloribase, fluobase, bromibase, iodobase, cyanobase, sulphobase, selenibase, telluribase, would stand in opposition to oxacid, chloracid, bromacid, iodacid, cyanacid, sulphacid, selenacid, telluracid. (862, &c.) Yet for convenience, the generic termination ide might be used without any misunderstanding; and so far the prevailing practice might remain unchanged. Resort to either appellation would not, agreeably to custom, be necessary in speaking of salts or other compounds analogous to them ; since it is deemed sufficient Jo mention the radical, as if the salt consisted of an acid combined with a radical, not an oxide. Ordinarily we say sulphate of lead, not sulphate of the oxide of lead. This last mentioned expression is resorted to, only where great precision is desirable. In such cases, it might be better to say sulphate of the oxybase of lead. 1059. The method of indicating the proportion of oxygen in an oxide, by changing the termination from ous to zc, has been generally adopted only in the case of the protoxide, and bioxide of nitrogen, the former being usually called nitrous oxide, the latter nitric oxide. In the Berzelian no- menclature, this method of discrimination has been extended to all the com- pounds formed with amphigen and halogen elements. Hence we have chlorure mercureux, and chlorure mercurique, for the protochloride, and bichloride of mercury ; and again, oxide mercureux and oxide mercurique for the protoxide and bioxide of the same metal. These Berzelian names translated into English would make mercurious chloride and mercuric chloride, mercurious oxide and mercuric oxide. 1060. It should be understood that the employment of the terminations in eux and ique, which in French answer for ic and ous in English, is ex- tended, by Berzelius, to the case of all oxides whether acids or bases. These words are, in my opinion, neither agreeable to the ear, nor sufficiently de- finite and descriptive. In the received nomenclature, besides the case above cited of the bioxide of nitrogen, the only other instance, of the employment of the letters ic to designate an oxide, is that of the protoxide of carbon, called carbonic oxide. Of the Origin of the erroneous Idea of a Ponderable Acidifying Principle. 1061. At the period when the French nomenclature was adopted, oxygen was considered as the sole acidifying principle, whence its name as already stated. (637.) Of course, every acid being supposed to consist of oxygen in part, it was enough to call it an acid to convey a correct idea of its com- position in that respect. But when, at a subsequent period, it was shown that many acids were destitute of oxygen, and that other substances were nearly as efficient as oxygen in generating acids by a union with acidifiable bodies, it became necessary to prefix syllables in order to distinguish the acid compounds produced by one acidifying principle, from those produced by others. (856, &c.) The term acidifying principle originated with the error of assigning that character exclusively to oxygen. From conve- nience, more than any conviction of its propriety, it was afterwards used oc- NITROGEN. 201 casionally in reference to chlorine, hydrogen, and other elements which are found to produce acids by combining with a variety of substances. It must be obvious that there is no adequate reason for considering any ponderable element as an acidifying principle. 1062. Subsequently to the creation of the word oxygen, the word radi- cal was employed to designate an oxidizable substance. It has since been extended by me to all substances which form acids or bases with the basacigen bodies. Of Acidity, j j 1063. Acidity and sourness were originally synonymous. By some of the older chemists, the solvent power of cer- tain acid or sour liquids, was ascribed to the sharpness of their constituent particles. To this acuteness in form, the power of penetrating and severing the combinations of other particles was attributed. With people in general, the words acid, and acidity, still retain their original signi- fication ; but by modern chemists, substances are associa- ted as acids which are destitute of sourness, and which are extremely discordant in their obvious properties. Thus we have in the group of acids, sulphuric acid and flint, vinegar and the tanning principle; also the volatile and odoriferous liquid called prussic acid, and the unctuous, insoluble, inert, concrete material for candles, called mar- garic acid. It might naturally excite the curiosity of the learner, to know by what common characteristic sub- stances so discordant had been affiliated. It would be in- ferred that there should be some test of acidity, by which to determine whether a new compound should belong to the class of acids or not. I am utterly ignorant of any other common characteristic, in these otherwise hete- rogeneous substances, besides that common preference for the poles, or "electrodes" of the Voltaic series, on which I have founded my definition of acidity and basid- ity; coupled with the inference, mentioned in a note, that any compound capable of neutralizing a base, is deemed to be an acid; and vice versa, any compound capable of neutralizing an acid, is deemed to be a base. (631.) To me it is quite evident that it is only upon one or the other of these characteristics, that many organic compounds which are called acids, or bases, can have any pretensions to be designated as they are. 1064. Among the characteristics of acidity heretofore relied on, is that of reddening vegetable blues. By the 26 202 INORGANIC CHEMISTRY. soluble acids, this property is generally possessed, al- though an aqueous solution of sulphurous acid is said to whiten litmus, the vegetable blue is generally employed as a test of acidity. But indigo is not reddened by any acid, although by nitric acid it is destroyed. Solubility, though usually a property of acids, is in many cases wanting, as in those of margaric and stearic acid, and others of simi- lar origin. The acid properties of silicic, and boric, acid, are displayed at temperatures incompatible with any other solubility, than that which is effected by the agency of caloric. Of Alkalinity. 1065. Among the metallic oxides which, agreeably to the definitions above given, are considered as bases, there are a certain number which are called alkalies, on account of some peculiarities which I shall proceed to mention. 1066. All the alkalies have a peculiar taste, called alka- line. They all produce, in certain vegetable colours, cha- racteristic changes, which differ according to the matter subjected to them, but are not varied by changing the alkali. 1067. They restore colours changed by acids, and are capable of neutralizing acidity. 1068. Acids neutralize alkalies, and restore colours de- stroyed by them. Acids do not usually combine with acids, nor alkalies with alkalies, but acids arid alkalies unite energetically with each other. 1069. By the reaction of alkalies with oils, soaps are generated, which are soluble in water. 1070. Besides the alkalies above named, there are four other metallic oxides, those of magnesium, barium and strontium for instance, which have been called earths, and which, in different degrees of intensity, have all the alka.- line properties abovementioned, excepting that, if not in- soluble, they have an inferior solubility, and that they do not form soluble soaps. 1071. There are also some vegetable compounds which possess, to a sufficient extent, the attributes of alkalies, to be classed among them. 1072. According to Bonsdorf, the halogen elements of Berzelius produce bases, which in some cases display alka- linity. He has noticed a change of colour, indicating an alkaline reaction, on litmus paper, reddened previously by NITROGEN. 203 an acid, and dipped into a solution of a chloride, either of calcium, magnesium, or zinc. 1073. I infer that acidity, basidity, alkalinity, and gal- vanic polarity, are due to some inscrutable influence of the imponderable cause, or causes, of heat, light, and electri- city. To a like influence I ascribe the sweetness of sugar, the pungency of mustard or pepper, and of essential oils, as well as the endless variety of odour with which these last mentioned products are endowed. It is evident that in the organic alkalies and acids, alkalinity and acidity are found to be associated with combinations of pondera- ble elementary atoms, which exist in other combinations without inducing alkalinity or acidity. 1074. It is my intention, as introductory to the subject of ammonia, to adduce a few experiments which illustrate the properties of alkalies in general. Experimental Illustrations of the characteristic Effects of the Alkalies on certain Vegetable Colours. 1075. Into infusions of turmeric, alkanet, Brazil wood, and rhubarb, a few drops of solutions of either of the alka- lies being introduced, turmeric, from a bright yellow, becomes brown; rhubarb, from nearly the same yellow, becomes red. Brazil wood, from a light red, becomes violet-red ; and alkanet, from red, becomes blue. Acids being added, the colours are restored, but by a sufficient quantity of alkali are changed, as in the first instance, and by acids again restored ; so that the experiment may be repeated several times with the same infusions. 1076. A blue infusion, obtained from red cabbage, is rendered green by an alkali. By adding some acid, the blue colour is restored; by a further addition of the acid, the infusion becomes red. An alkali being next intro- duced, it becomes blue, and by a further addition of alkali, the green colour reappears. By alternately using acids and alkalies, these changes may be repeated several times. 1077. The power of various acids in reddening infusions of litmus, shown ; and, subsequently, the restoration of the blue colour by an alkali. 204 INORGANIC CHEMISTRY. COMPOUNDS OF NITROGEN WITH HYDROGEN. Of Ammonia. 1078. As substances which are analogous in their most important properties, are often utterly different in their composition, it is impossible to adopt any arrangement in treating of them, which may be in both respects satisfac- ' tory. The compound which is the subject of this article, was naturally associated with the other alkalies, when their composition was unknown; although now generally ranged with the compounds of nitrogen, whilst its former associates are placed among the metallic oxides. 1079. This classification has become the more proper, as agreeably to the view latterly presented by Berzelius, it appears to be doubtful, whether ammonia be an alkali. But of this I shall speak more fully, in treating of ammo- nium. (1106, &c.) 1080. Formerly, besides ammonia, only two other alka- line substances were known, soda and potash, or potassa. These being difficult to vaporize, obtained the name of fixed alkalies, while ammonia being naturally aeriform, was called the volatile alkali. 1081. A new mineral fixed alkali was discovered in 1817, and named lithia. It was procured from a stone called Petalite. Hence its name from the Greek A,fc/ 5 , stony. 1082. Preparation of Ammonia. Ammonia is obtained from sal-ammoniac, the salt from which it received its name. 1083. To evolve this alkali in the gaseous state, equal parts of sal-ammoniac and quicklime, both finely pulve- rized, are to be heated gradually in a glass matrass. The ammonia is partially extricated by the mere mixture of the materials; but heat is necessary to complete the ope- ration. 1084. Sal ammoniac, according to the opinion generally entertained, is a compound of chlorohydric or muriatic acid and ammonia. The lime having a greater affinity for the acid than the ammonia, by simple affinity combines with it, and liberates the alkali as a gas, the state which it na- turally assumes when isolated. A different view of this subject is taken by Berzelius, which will be explained when treating of ammonium. (1109, 1110.) NITROGEN. 205 1085. When it is an object to have the gas perfectly free from humidity, it is necessary to arrest the process as soon as moisture begins to condense in the neck of the re- ceiver; or to interpose, between the neck, and the reci- pient used to receive the gas over mercury, a tube con- taining dry hydrate of potash in small fragments. N Experimental Illustration of the Process for obtaining Gaseous Ammonia. 1086. A flask, containing equal parts of quicklime and sal-ammoniac, both well pulverized and thoroughly inter- mingled, is exposed to as much heat as the glass will bear. 1087. A bell glass is so placed over the mercurial cis- tern, as to receive any gas which may pass from the ori- fice of a tube, luted at one end into the flask charged with the materials, and at the other entering the mercury so as to be under the bell. This apparatus is represented in the following cut. 1088. Properties of Ammonia. Ammonia acts like an alkali upon the organs of taste, upon vegetable colours, and in neutralizing acidity. A very small proportion of this gas, diffused in the air, is intolerable to the eyes and organs of respiration; yet when extremely dilute, the odour is agreeably stimulating. Its specific gravity is 0.5897, and 100 cubic inches weigh 18.28 grains. It is not inflammable in the air, yet inflames with chlorine spontaneously, and with oxygen, by the aid of an electric 206 INORGANIC CHEMISTRY. spark, or galvanic ignition. A candle flame is at first en- larged and afterwards extinguished by immersion in this gas. Water absorbs it with surprising velocity, and will hold from 450 to 670 times its bulk. Ice melts in it more speedily than in a fire. 1089. Heat either decomposes, or volatilizes, all ammo- niacal compounds; and either of the fixed alkalies, or of the three more powerful alkaline earths, disengage ammo- nia from any of the acids with which it may be combined. 1090. Ammonia, by refrigeration alone, may be con- densed into a liquid at 40 F. By a pressure of six at- mospheres and a half, Mr. Faraday succeeded in liquefy- ing it at the temperature of 50 F. 1091. The decomposition and analysis of ammonia have been attempted by ignition with oxygen gas. I have often caused a mixture of it with oxygen, to inflame by means of a wire ignited by galvanism. I believe it to be almost impracticable to ascertain the result accurately by measurement, on account of the liability of ammonia to be absorbed by the moisture of the apparatus, the water produced by the combustion, arid the mercury employed to confine the gases. 1092. A spontaneous and explosive combustion ensues between chlorine and the hydrogen of gaseous ammonia. When chlorine is passed in bub- bles through concentrated liquid ammonia, a reaction takes place with so much noise, as apparently to endanger the containing vessel. This process has already been mentioned as one of the means of obtaining nitrogen. 1093. In its reaction with ammonia iodine differs from chlorine. When iodine is brought in contact with dry ammoniacal gas, it forms a thick black fluid, which, when saturated with ammonia, becomes more liquid. This compound is decomposed by water forming the iodide of nitrogen. (1032.) 1094. With various metallic oxides, ammonia forms explosive com- pounds; especially those known as fulminating gold, and the most dan- gerous species of fulminating silver. By these appellations, however, other compounds of those metals are designated. By some inexplicable influence, probably electro-chemical, the affinities between the oxygen and hydrogen are suspended without being destroyed. Yet by slight causes, whether me- chanical or chemical, the equilibrium is subverted with explosive violence. Experimental Illustrations. 1095. Sal-ammoniac and quicklime, being powdered, and mixed in small glasses, pungent fumes are emitted. Am- monia extricated by the process above described, and col- lected in bell glasses over mercury. The introduction of a few drops of water causes the gas to disappear. Ice, in the same way introduced is liquefied, and causes a like re- sult. Characteristic changes effected in the colour of wa- NITROGEN. 207 ter, tinctured by turmeric, alkanet, Brazil wood, and rhu- barb. 1096. Evolution of gas shown by means of potash and an ammoniacal salt, introduced into a glass vessel over mercury. 1097. Equal volumes of ammonia and chlorohydric acid, mixed, and condensed into a solid, constituting sal- ammoniac. 1098. Ammonia inflamed with oxygen gas: also with chlorine. 1099. Synthesis of ammonia by nitric oxide and hy- drogen, heated with platina sponge. Of the Composition of Ammonia. 1100. According to Berzelius, ammonia was first ascertained to be a compound of nitrogen and hydrogen, by his celebrated countryman, Scheele. At a later period, Berthollet ascertained the ratio in which these substances exist in it, which is by volume that of three of hydrogen to one of nitrogen, condensed into two volumes: and by weight, 3 of hydrogen to 14 of nitro- gen. See Table, page 189. 1101. The partial decomposition of ammonia may be effected by subject- ing it to a succession of electrical sparks. Each spark causes the decom- position of a portion of the gas ; but as the process proceeds, it becomes more difficult, so that a complete decomposition is impracticable. That portion which is decomposed, is doubled in volume ; since the three volumes of hydrogen and one of nitrogen occupy, while combined, but half of the space which they would fill if uncombined. 1102. Ammonia, by being made to pass through tubes at a red heat, is resolved into its constituents. This result is promoted by the presence of metallic wire. Any metal will have more or less effect, but iron is most efficacious. It appears from recent experiments of Despretz, that this me- tal, by continued exposure, may be made to take up nearly twelve per cent, of its. weight, becoming a nituret by the absorption of the nitrogen of the ammonia. It is supposed that other metals, which, after a like exposure, exhibit no increase of weight, successively receive and abandon. nitrogen; an operation which appears to be singular and mysterious. The metals become brittle during this process. Probably their influence is in its nature electro- chemical. In its effects it appears to be the reverse of that by which the union of the elements of water is promoted by the presence of some metals in a state of minute division. Process for obtaining Water from Ammonia. 1103. If instead of being conveyed into a bell glass over mercury, the gas be received in water contained in a phial, the water may be saturated, constituting aqua ammoniac, or water of ammonia. The saturation may be effected in an apparatus, similar to that represented in the following cut. 208 INORGANIC CHEMISTRY. 1104. The absorption of ammoniacal gas by water, causes so much heat, that it is difficult to produce a saturated solution, without assisting the refrigeration by means of ice. 1105. Water saturated with ammonia, when gradually cooled to the temperature of 40 F., crystallizes in long needles having a silky gloss. No doubt these crystals owe their existence to the presence of water, which exists in them as water of crystallization. Water of ammonia is lighter than water. In combining with the gas, the water loses weight in proportion to the degree of impreg- nation. At the maximum, at ordinary temperatures, the alkali constitutes about one-third of its weight. Of Ammonium. 1106. It is well known that Davy resolved potash and soda severally into metals and oxygen, by exposing those alkalies to the divellent influence of the Voltaic current. Subsequently, Berzeliu's, not having at command an apparatus sufficiently powerful, when unassisted, to effect this decompo- sition, ascertained that, by placing mercury in contact with a moistened fixed alkali, and in communication with the negative pole, while the alkali communicated with the positive pole, an amalgam would result either of potassium or sodium, according to the alkali employed. 1107. The results, when ammonia is subjected to the galvanic circuit in contact with mercury at the negative pole, having a perfect analogy, as respects the production of an amalgam, with those obtained by a similar exposure of the other alkalies, as above mentioned, led naturally to the NITROGEN. 209 inference that the causes were analogous; and that, in the case in question, no less than in the others, a metallic radical had been deoxidized and united with the mercury. This inference was rendered more plausible by the evolution of oxygen at the positive pole during the formation of the amal- gam. Yet ammonia was known to consist of hydrogen and nitrogen; and to consider either or both of these as oxides, was inconsistent with all the knowledge otherwise obtained respecting them, By some chemists, how- ever, nitrogen was conjectured to be the oxide of a metal, with which this amalgam was supposed to be formed. For this supposed metal, the name of nitricum was suggested. Hence the contact of the amalgam with water was conceived to cause the absorption of oxygen by the nitricum, and consequently the extrication of hydrogen. 1108. Gay-Lussac and Thenard explained the formation of the amalgam, by supposing the absorption of ammonia by the mercury, together with a portion of hydrogen derived from the simultaneous decomposition of water. 1109. Berzelius admits the fact of the union of the elements of ammonia and hydrogen with the mercury, in the proportions alleged by the distin- guished philosophers above named; but conceives that, by the addition of an atom of hydrogen to the ammonia, this alkali is converted into a metal, which he calls ammonium. To the union of this metal with mercury, he ascribes the production of the amalgam; and to a resolution of the metal into its elements, the evolution of the ammonia and hydrogen. When an atom of ammonia is presented to an atom of water, he infers that the hy- drogen of the water converts it into ammonium, which is simultaneously oxidized by the oxygen. Hence an atom of ammonia, when combined with an atom of water, may be considered as acting as an oxybase of am- monium. When gaseous ammonia is presented to chlorine, one portion of it is decomposed, of which the nitrogen is liberated, while the hydrogen converts another portion into ammonium. This forms with the chlorine a chloride of ammonium^ and, accordingly, by this appellation, sal ammo- niac, or muriate of ammonia, must be designated, agreeably to the hypo- thesis under consideration. 1110. When in the process already given for obtaining ammonia, chloride of ammonium (sal ammoniac) is mingled with the oxide of cal- cium (lime,) by double electrive attraction, the chlorine combines with the calcium, and the oxygen with one atom of the hydrogen in the ammonium; so that water and ammonia are evolved. The latter assumes the gaseous form, while the water unites with the chloride, and remains in union with it, if the heat be not raised unnecessarily, and continued too long. 1111. If we attempt to decompose ammonia without the assistance of mercury, it yields nothing but hydrogen and nitrogen ; yet, to produce the amalgam, it is sufficient that the wire employed be coated with mercury. The globule of mercury which is left after the spontaneous decomposition which the mass sustains, is in volume surprisingly minute comparatively with the amalgam which it contributed to form. 1112. The most convenient mode of obtaining the ammoniacal amal- gam, is to place a globule of the amalgam of potassium in a cavity of a piece of chloride of ammonium, slightly moistened. The globule soon enlarges to many times its previous dimensions, by the absorption of the ammonium, which relinquishes its chlorine to the potassium. 1113. The ammoniacal amalgam, agitated in dry atmospheric air, yields hydrogen and ammoniacal gas. The same gaseous substances are extri- cated from it when plunged into ether or naphtha. The ammoniacal 27 210 INORGANIC CHEMISTRY. amalgam may be preserved for some time, if surrounded by hydrogen, or included in a dry and well closed bottle. When thus protected, and the absence of water is insured by the presence of a small proportion of potas- sium, it may be kept unchanged for several months. 1114. Berzelius does not consider ammonia as capable of becoming a base, without first being converted into ammonium by the acquisition of hydrogen. In this state, without further change, it can, like other metals, form a salt by combining with any of the halogen substances. But to com- bine with oxacids, the ammonium must, like other metals, be oxidized. The presence of water at once metallizes and oxidizes ammonia. The hydrogen converts the ammonia into a metal, while the oxygen converts that metal into an oxide. 1115. When gaseous ammonia precipitates, from an aqueous solution of a haloid salt,* a metal in the state of oxide, water is decomposed, the hydro- gen converting the ammonia into the metal ammonium, while the oxygen converts the metal into an oxide. Meanwhile, the ammonium, combining with the halogen element of the haloid salt, takes the place previously occu- pied by the metal which has been oxidized. 1116. Agreeably to the view taken above, water, by its contact with ammonia, at once metallizes and oxydizes it, since the hydrogen converts it into ammonium, while the oxygen, at the same time, converts it into an oxide. Thus the formula of ammonia united to water, would be N H 3 X H ; but when it is resolved into N H 4 X 0, an oxide of ammonium. 1117. It must also follow, that it is not by ammonia that the part of an alkali is performed when entering the arena of alkaline reaction ; with the aid of water a transformation takes place, so that the oxide of ammonium is really the ammoniacal alkali. Of course ammonia cannot, consistently with this explanation, be considered as an alkaline gas. 1118. I deem it expedient to adopt the Berzelian doctrine, as it is neces- sary to the symmetry of our classification both as respects acids, bases, and chlorides. To consider ammonia, per se, as forming salts with oxacids, or with the halogen bodies, would involve an anomalous deformity, as in all other cases of the union of inorganic acids and bases, the same basacigen ingredient exists both in the acid and the base. Experimental Illustrations. 1119. In a cavity, made in a bit of muriate of ammonia, in communication with one of the poles of the Voltaic pile, a moistened globule of mercury is supported. The mercury is made to communicate with the other pole. The metal swells rapidly, and assumes all the characteristics of an amalgam. 1120. An amalgam of potassium, being introduced into a cavity in a piece of sal ammoniac, is rapidly converted into the ammoniacal amalgam, with a prodigious enlarge- ment in bulk. * A salt formed by a halogen element. (636.) PHOSPHORUS. 211 SECTION III. OF PHOSPHORUS. 1121. Preparation. Phosphorus is obtained from the phosphate of soda in urine, or the phosphate of lime in bones. Impure phosphoric acid may be extricated from the earth of bones, by the stronger affinity of sulphuric acid. As, at a high temperature, charcoal takes oxygen from phosphorus, the phosphoric acid is decomposed by ignition with it in a retort, the beak of which is so introduced into water, as to have the orifice a little below the surface. Phosphorus distils into the water, and condenses in tears. 1122. Agreeably to another process, the phosphate of soda, which may be procured at the shops, is decomposed by nitrate of lead, by complex affinity. The phosphorus is separated from the resulting phosphate of lead, by distillation with charcoal, as in the process above men- tioned. 1123. Properties. Phosphorus is often of a light flesh colour, but when pure is colourless and translucent. It is rather harder than wax, but is more easily divided by a knife. Phosphorus melts at 108, and inflames at 148. At 550 it boils, and may be purified by distillation from a retort filled with hydrogen gas, receiving the product under water. Phosphorus is insipid and probably inodorous; but, in consequence of its oxidizement, it emits a feeble alliaceous odour of phosphorus, or hypophosphoric acid. When pure it is flexible, but the presence of l-600th of sulphur renders it brittle. Its specific gravity is 1.77. Subjected to the rays of the sun, it acquires a red colour. If heated to 155 and suddenly cooled, it becomes black. Thenard, however, states that this change cannot be effected in phosphorus which has not been repeatedly distilled. He suggests it as possible, that the colour of phosphorus, when pure, is black ; and that the colour which it usually assumes, may be due to the presence of hydrogen, which has been long known to be evolved, when phosphorus, in the usual state, is fused and subjected to the Voltaic current. 1124. Exposed to the air at ordinary temperatures, phos- phorus combines slowly with oxygen, appearing luminous in the dark, but without any sensible evolution of heat. Less heat is requisite to cause the inflammation of phos- 212 INORGANIC CHEMISTRY. phorus in atmospheric air than in oxygen ; and less also is necessary in this last mentioned gas, in proportion as the pressure is reduced. When sprinkled with powdered sulphur, carbon, fluoride of calcium, carbonate of lime, and various other bodies, and placed in a receiver from which the air is subsequently exhausted, phosphorus in- flames. Professor Alexander D. Bache, who has much enlarged the list of substances capable of producing this result, has succeeded in inflaming phosphorus in an exhausted receiver by enveloping it in muslin, or in paper pierced with small holes. He conceives that, with the ex- ception of bodies exercising a chemical affinity, as in the instance of sulphur, the substances associated with the phosphorus act mechanically, and have upon it no other effect than that of promoting its union with the oxygen remaining in the receiver. This opinion is corroborated by the fact that the removal of the air may be too rapid, or too complete, to produce the inflammation. 1125. Phosphorus may be crystallized from its solution in boiling naphtha, by gradual refrigeration. Like sulphur, phosphorus, in volatilizing, produces a feeble light, without entering into any chemical combination. Water in which phosphorus has been kept, oxygen being excluded, acquires the power of shining when agitated. The admission of air destroys this phosphorescent property. Phosphorus is oxidized by the action of nitric or nitrosonitric acid, and converted into phosphoric acid. Experimental Illustrations of the Properties of Phosphorus* 1126. Phosphorus exhibited, and inflamed by friction or a gentle heat. Luminous appearance in the dark. Com- bustion in oxygen, (654,) in nitrous, and nitric oxide, under hot water by a jet of oxygen, and by nitrosonitric acid. (1131.) 1127. Anomalous combustion of phosphorus consequent to rarefaction. Combustion of Phosphorus in Nitric Oxide. 1128. The backwardness of the gaseous oxides of nitrogen to part with their oxy- gen to substances, under circumstances in which it would be readily yielded by at- mospheric air, has been already mentioned, and a method of illustrating it has been described. (969.) The opposite engraving represents an apparatus, which may be used to extend the illustration to nitric oxide, which, producing a corrosive fume of nitrous acid by admixture with oxygen, cannot be employed in apparatus requiring the aid of an air-pump, without corroding the metal of which such instruments are partially constituted. The apparatus in question is nearly the same as that used for Combustion of Phosphorus in Nitric Oxide. (Page 212.) PHOSPHORUS. 213 the separation of nitrogen from atmospheric air. There are, however, in this, two additional tubes; and the bell employed is without any cap or cock. The cock at A, to which a gum elastic bag, supplied with oxygen gas, is attached, communicates with a pipe, which descends close along the inner lateral surface of the cylindrical copper vessel till it reaches the bottom, then bends at right angles, and proceeds along the bottom of the vessel till it reaches the copper pipe in the axis of the vessel. Next it bends at right angles upwards, and ascends vertically in close contact with the pipe, till it reaches the copper cup, g, by which the pipe is surmounted. It is there so recurved as to overhang and direct its orifice, t, downwards, into the cavity of the copper cup. 1129. Another tube, u, proceeds from its junction with a screw and cock, C, on the other side of the vessel, and descends to the bottom, rising again, like the tube abovementioned, along the central pipe, till it reaches somewhat above the brim of the cup, where it terminates without a curvature. After the proper quantity of phosphorus has been placed in the cup, the atmospheric air may be allowed to es- cape from the bell glass through the cock, C, by sinking it into the water, with which the vessel must have been filled nearly to the brim. The air being expelled, and a communication made with a self-regulating reservoir of nitric oxide, by means of the flexible leaden tube attached to the cock for that purpose, the bell may be sup- plied with a quantity of this gas, sufficient to occupy about two-thirds of its capacity. The cock being then closed, and the communication with the reservoir interrupted, a red-hot iron must be introduced through the bore of the central pipe, p, till it touches the cup. For this purpose, it is of course necessary that the apparatus should be upon a table with a suitable aperture, and of a height sufficient to allow the iron to enter the orifice of the pipe, p. 1130. Although by the heat of the incandescent iron, the phosphorus will be fused, no combustion will ensue, until, by opening a communication with the gum elastic bag, a small quantity of oxygen is allowed to enter. But no sooner is this permitted to take place, than a most brilliant and almost explosive evolution of heat and light ensues. A higher temperature is requisite to ignite phosphorus in nitric than in nitrous oxide. Reaction of Phosphorus toith Nitroso-nitric Add. 1131. If into a tall tube of about an inch and a half in diameter, and fifteen inches in height, some strong nitric acid be introduced, and about five grains of phosphorus, a reaction will ensue, which is invariably energetic, and sometimes ex- plosive. The phosphorus abstracting oxygen, the acid is converted into nitric oxide gas and nitrous acid vapour, which are copiously evolved, so as to fill the upper part of the tube, and overflow it with a beautiful red fume. Meanwhile, vivid flashes arise from the oxygenation of the phos- phorus, and pieces of it are occasionally thrown up into the gas in the tube, where a vivid com- bustion ensues between the phosphorus, and the oxygen of the nitric oxide gas or nitrous acid. 1132. The residual nitric acid will be found in- termingled with phosphoric acid. 1133. Latterly, in performing this experiment, I have surrounded the tube with a very stout glass cylinder, and another of wire gauze; as upon one occasion a violent explosion took place, which did much damage to my apparatus. If the phosphorus be reduced into small fragments, the risk of an explosion is increased. Heating the acid, before the addition of the phosphorus 5 , en- sures an explosive reaction. i Application of Phosphorus to Eudiometry. 1134. One of the most simple modes of ascertaining the quantity of oxygen in the air, is to introduce into a graduated tube, standing over water, and containing 100 measures of air, a stick of phosphorus, supported by a wire. The phosphorus slowly dissolves in the nitrogen, and, combining with the oxygen, condenses with it, and 214 INORGANIC CHEMISTRY. causes a corresponding absorption of the water. When, by these means, the oxy- gen is all removed, the quantity of nitrogen remaining will be known by inspecting the graduation- The difference between this quantity and 100, the number of mea- sures taken, is the quantity of oxygen present. A Simple Atmospheric Eudiometer by Phosphorus. 1135. If a cylinder of phosphorus be supported upon a wire (as represented in the adjoining cut,) within a glass matrass, inverted in a jar of water, the oxygen of the included air will be gradually absorbed. In order to determine the quantity of oxygen in the air, we have only to ascertain the ratio of the quantity of gas absorbed, to the whole quantity of air included in the matrass at the commencement of the process. 1136. This object may be attained by weighing the matrass when full of water, and when containing that portion only which rises into it in consequence of the absorption. As the weight in the first case is to the weight in the last, deducting the weight of the glass in both cases, so will 100 be to the number of parts in 100 of atmospheric air, which consist of oxygen gas. 1137. Again, the contents of the vessel may be dis- covered by the sliding-rod gas measure, (936,) and the absorption measured by introducing from the same in- strument, as much air as will compensate it. As the whole content to the quantity which compensates the absorption, so is 100 to the quantity of oxygen in 100 parts of the atmosphere. 1138. If the neck of a vessel of this kind hold about one-fourth as much as the bulb, by graduating the neck, so that each division will represent a hundredth part of the whole capacity, the result may be known by inspection. 1139. Eudiometrical processes by the slow combustion of phosphorus are tedious, requiring many days to complete them, and consequently the aid of barometrical ob- servations to ascertain and allow for any intervening changes in atmospheric pres- sure. 1140. It is alleged that nitrogen is enlarged one-fortieth of its bulk, by the phos- phorus which it dissolves. This is to be deducted in estimating the residual gas. 1141. The action of the phosphorus may be accelerated by heat; but in that case the operation must be performed over mercury ; and the manipulation will be found troublesome and precarious. 1142. I have never in this way, obtained results comparable in accuracy and uni- formity, to those procured by the hydro-oxygen eudiometer. (940, &c.) Volumescope for the Analysis of Atmospheric Mr by Phosphorus. 1143. A volumescope has been described, (818,) for showing the diminution of bulk in five volumes of atmospheric air, consequent to the admixture of nitric oxide. The same apparatus may, with some modification, be employed to show the diminu- tion of volume resulting from the combustion of phosphorus. This object is effected by associating with the volumescope, the apparatus employed for the combustion of phosphorus in oxygen. (654.) For this purpose, the volumescope, instead of being situated over the pneumatic cistern, should be placed in a small tub, into the bottom of which is inserted a tube, supporting, at the upper extremity, the cup for the phos- phorus. The phosphorus being placed in the cup, and water in the tub, this liquid is raised by an air-pump, until no more than five volumes of air remain in the cylin- der. The phosphorus is then ignited by means of a red-hot iron, and the process conducted as already described. (922.) As soon as the expansion resulting from the heat of the combustion ceases, it will be seen that a little more than one volume out of the five has been condensed. COMPOUNDS OF PHOSPHORUS WITH OXYGEN. 1144. These compounds are four in number; one oxide, oxide of phosphorus, and three acids, hypophosplwrous, phos- PHOSPHORUS. 215 phorous, and phosphoric acid. Their composition is as follows : Three atoms of phosphorus, equivalent 48, Two atoms of phosphorus, equivalent 32, I with one atom of oxygen, equivalent 8, form oxide of phosphorus, equiva- lent 56. with one atom of oxygen, equivalent 8, form hypophosphorous acid, equiva- lent 40. with three atoms of oxygen, equivalent 24, form phosphorous acid, equiva- lent 56. with five atoms of oxygen, equivalent 40, form phosphoric acid, equivalent 72. Of Oxide of Phosphorus. 1145. When phosphorus, melted under hot water, is subjected to a jet of oxygen from a tube with a capillary orifice, oxide of phosphorus and phosphoric acid are produced. The acid dissolves, and the oxide, being at first suspended in the water, subsides subsequently in red flakes. This oxide is insipid and inodorous. It is not luminous in the dark, even when rubbed. At a heat a little below redness in close vessels, it is decomposed into phosphoric acid and phosphorus. If the air be admitted, phosphoric acid is the sole product. The oxide of phosphorus takes fire spontaneously in chlorine, producing the perchloride of phosphorus and phosphoric acid. It is inflamed by the action of nitric acid. With chlorate of potash it ex- plodes violently; also with nitrate of potash previously warmed. The white matter with which phosphorus becomes coated when kept, in water, and which is generally supposed to be a hydrate of the oxide, is stated by Thenard to be a hydrate of phosphorus. Production of Oxide of Phosphorus experimentally illustrated. 1146. Production of oxide of phosphorus, by the reaction of oxygen with that substance, while in fusion under hot water. Of Hypophosphorous Acid. 1147. This acid is obtained by precipitating the baryta from an aqueous solution of hypophosphate of that base. The acid remaining in solution, may be so concentrated by evaporation as to become a vivid liquid, highly acid, and even crystallizable. It is an energetic deoxidizing agent, and forms numerous salts, all of which are soluble in water, whereas several of the phosphates are insoluble. Of Phosphorous Acid. 1148. This acid has been generally considered as the product of the slow combustion of phosphorus with atmospheric oxygen; but Thenard alleges that this product is a peculiar acid, intermediate in its degree of 216 INORGANIC CHEMISTRY. oxidation between phosphorous and phosphoric acid, and to which he has given the name of hypophosphoric acid. Phosphorous acid may be pro- cured by passing vaporized phosphorus over corrosive sublimate heated in a tube. Chloride of phosphorus results, which, by reaction with water, produces chlorohydric and phosphorous acids. The chlorohydric acid, being more volatile, may be expelled by heat. 1149. Phosphorous acid is a colourless, inodorous, crystalline substance, possessing a pungent taste, and reddening litmus paper. Like hypophos- phorous acid, it possesses powerful deoxidizing properties. Of Phosphoric Acid. 1150. Preparation. Phosphoric acid may be obtained by adding sulphuric acid to phosphate of baryta suspended in water. The sulphuric acid unites with the baryta, forming an insoluble salt, which precipitates while the phosphoric acid remains in solution. When phosphorus is gradually added to -nitric acid, phosphoric acid is gene- rated, and remains mingled with the residual nitric acid. 1151. Properties. Phosphoric acid is an inodorous, co- lourless, viscid liquid, possessing in a high degree the pro- perty of reddening litmus. It cannot be obtained in a state of liquidity free from water. When exposed to a red heat and afterwards cooled, it forms a transparent brittle glass. This fusion should be effected in a platinum crucible ; since phosphoric acid, when heated to redness, attacks either glass or porcelain. The acid, if examined after this ex- posure to heat, is found, although its composition remains the same, to have acquired new properties. On this ac- count, the name of paraphosphoric has been given to it ; while the term phosphoric is applied to designate the acid in the state first described. Nitrate of silver yields with phosphoric acid a yellow precipitate ; with paraphosphoric acid a white one. Albumen is coagulated by the latter, but not by the former. 1152. Solid paraphosphoric acid, when exposed to the air, deliquesces, and is in a few days converted into phos- phoric acid. The same change is produced in a short time by boiling water. The solid white flakes which are ob- tained during the quick combustion of phosphorus with oxygen, consist of paraphosphoric acid. It may likewise be produced by fusing the biphosphate of soda, which by these means is converted into a paraphosphate. Mr. Graham, who has made a number of interesting experi- ments on this subject, states that the acid which is con- PHOSPHORUS. 217 tained in fused phosphate of soda, is a third species of phosphoric acid, which coincides in composition with the others, but not in properties. To this species he has given the name of pyrophosphoric acid. 1153. To bodies which possess different properties, while containing the same number of atoms of the same ele- ments, and having the same atomic weight, the term iso- meric has been applied. Thus, phosphoric, paraphosphoric, and pyrophosphoric acids are said to be isomeric bodies. Of the Chlorides of Phosphorus. 1154. It has been shown, (983,) that phosphorus burns spontaneously in chlorine. If the chlorine be in excess, the perchloride is formed; if the phosphorus be in excess, the sesquichloride is obtained. The sesquichlo- ride is a transparent, colourless, fuming, inflammable liquid, heavier than water, and having a disagreeable smell. When brought into contact with water, a reciprocal decomposition takes place, and chlorohydric and phos- phorous acid are produced. The perchloride is a white, crystalline, in- flammable body, which is converted into vapour at a temperature much below 212. It forms a neutral compound with ammonia, and its vapour is alleged to redden dry litmus paper. Hence, by some chemists, it is considered as an acid. I doubt whether litmus paper is ever reddened by an acid, unaided by water. The perchloride and water decompose each other, forming phosphoric and chlorohydric acid. The chlorine bears the same ratio to the phosphorus in these chlorides, as the oxygen bears to the phosphorus in phosphorous, and phosphoric acid. Of the Bromides and Iodides of Phosphorus. 1155. The sesquibromide is a yellow fuming liquid; the perbromidc, a crystalline volatile solid. In their reaction with water and composition, they agree with the chlorides of phosphorus. Iodine appears to combine with phosphorus in almost every proportion. There are, however, at least two definite comoinations, which correspond in composition with the chlo- rides and bromides. Of the Sulphides and Selenides of Phosphorus, commonly called Sulphu- rets and Seleniurets. 1156. When phosphorus is melted with sulphur, or when sprinkled with it, and placed in a receiver from which the air is subsequently withdrawn, (1124,) a sulphide of phosphorus is formed. This sulphide may consist of various proportions of its ingredients, according to the circumstances under which it is produced. Sometimes it is liquid, sometimes solid. 1157. Selenium, like sulphur, combines with phosphorus in almost every proportion. The sulphides and selenides of phosphorus are decomposed by water. 1158. The incorporation of sulphur with phosphorus, when effected by heat, is sometimes productive of explosion; and the resulting mass is spon- taneously inflammable in the air; being the sole active ingredient in some friction matches. 28 218 INORGANIC CHEMISTRY. COMPOUNDS OF PHOSPHORUS WITH HYDROGEN. Of Protophosphuretted Hydrogen. 1159. Protophosphuretted hydrogen may be obtained by heating a con- centrated solution of phosphorous acid, or by adding phosphorus to the ma- terials for generating hydrogen. 1160. Properties. It is a colourless, inflammable gas, with an odour similar to that produced by the combustion of arsenic. Under the ordinary pressure of the atmosphere, protophosphuretted hydrogen does not inflame spontaneously with oxygen ; but, if the pressure be reduced about one-third, combustion ensues. 1161. On meeting with oxygen, this gas becomes luminous in the dark, in consequence of the slow combustion of the phosphorus ; though the heat evolved is inadequate to inflame the hydrogen. If the process for pro- ducing the philosophical candle, (806,) be repeated with the addition of some comminuted phosphorus to the materials, protophosphuretted hydrogen will be generated, and, escaping into the air, will produce a jet luminous in the dark. Of Perphosphuretted Hydrogen. 1162. Perphosphuretted hydrogen may be produced by the reaction of chlorohydric acid with the phosphuret of calcium, which is obtained by sub- jecting lime to the vapour of phosphorus at a bright red heat in a porcelain or coated glass tube. The gas may also be evolved by heating in a retort, 75 grains of phosphorus, 1500 of slacked lime, with 4 ounces of water; or 50 grains of caustic potash, and 40 of phosphorus, moistened by 60 drops of water. The phosphorus should be added first, and the potash last ; as the heat which it evolves, contributes to the heat required for the operation. The body of the retort should be filled with hydrogen, or a few drops of ether should be added, to prevent the first portions of the gas from inflaming with the atmospheric oxygen of the retort. By its affinity for the phospho- rus, and the metal of the phosphuret, the oxygen of the water is separated from the hydrogen, which, while nascent, unites with a portion of the phos- phorus, and forms perphosphuretted hydrogen. 1163. The following cut represents the apparatus usually employed for obtaining perphosphuretted hydrogen. 1164. The beak of the retort being depressed below the surface of the PHOSPHORUS. 219 mercury, each bubble as it escapes into the atmosphere, explodes. It pro- duces at the same time a dazzling flash, which is transformed into a beau- tiful wreath of smoke, consisting of aqueous vapour and phosphoric acid, created by the oxygenation of the hydrogen and phosphorus. Each wreath, as it rises, expands in diameter, and, when the bubbles succeed each other quickly, a series of them may be seen in the air at the same time. 1165. Properties. Perphosphu retted hydrogen is a colourless gas, pos- sessing an alliaceous smell, and a bitter taste. Water dissolves it in small quantity, forming a yellow solution, which has a bitter taste, and a smell resembling that of the gas. When this gas is brought in contact with oxy- gen, or atmospheric air, it explodes with a loud noise and a vivid flash ; being converted into phosphoric acid and water. The same mixture, in narrow tubes, undergoes a similar change slowly, and without the evolution of heat and light. 1166. Perphosphuretted hydrogen may be decomposed either by heat, by the electric spark, or by the rays of the sun. Professor Rose considers protophosphuretted and perphosphuretted hydrogen as isomeric, and of course similar in composition, though different in properties. If the opi- nions of Rose are correct, one should be called phosphuretted hydrogen, the other paraphosphuretted hydrogen. (1153.) 1167. Chemists do not -agree in their statements respecting the composi- tion of the compounds of hydrogen with phosphorus. Method of exhibiting the, Inflammation of Small Portions of Gas. 1168. This figure illustrates an advantageous employment of the sliding-rod eudi- ometer, in exhibiting the spontaneous combustion of phosphuretted hydrogen, the splendid colour of the flame of cyanogen, and other experiments, where the combus- tible character of a small quantity of gas is to be shown. 1169. For the experiments in question, the instrument is charged, agreeably to the mode already described in the case of the eudiometers, by introducing the apex into any bell glass or other vessel holding the gas, and drawing out the rod; by which a portion of the gas, equivalent in bulk to the part of the rod withdrawn, enters the receiver of the eudiometer through the hole in the apex. The receiver being then removed from the bell glass, and held up in a position favourable for observation, the rod is slowly returned into its tube, so as to expel the gas in a jet suitable for inflam- mation. In the case of perphosphuretted hydrogen, the gas burns spontaneously as soon as it escapes from the apex. In the case of other inflammable gases, inflamma- tion is produced by the flame of a taper. 220 INORGANIC CHEMISTRY. SECTION IV. OF CARBON. 1170. Nature presents us with the most beautiful and purest specimens of this substance. The diamond is pure carbon. When equal weights of charcoal and diamond are severally exposed to the focus of a powerful lens in oxygen gas, included in different bell glasses, they are both converted into carbonic acid, from which, by ignition with potassium, carbon may be precipitated. 1171. Carbon is very abundant in nature, in the various kinds of fossil coal, from anthracite or plumbago, in which it is nearly pure, to the variety called candle, or cannel coal, which abounds with bitumen. In bituminous coal there is much hydrogen. Carbon pervades vegetable and animal matter as an essential element. It is, especially, a constituent of the fibres of wood. '1172. Until of late, plumbago was considered as a che- mical compound of iron with carbon. Berzelius alleges it to be carbon mingled, but not combined, with iron and other impurities. 1173. I ascertained that anthracite, when completely burned in oxygen gas, produced no diminution of volume, the products being water and carbonic acid. I infer, therefore, that the combustible portion of this coal con- sists almost solely of carbon, united with hydrogen and oxygen in the proportion for forming water. It may, in fact, be deemed an hydrate of carbon. 1174. Preparation. In the laboratory, charcoal is ob- tained, sufficiently pure, by heating wood intensely in close vessels. In the large way, it is procured by igniting large quantities of wood, so covered with earth, that the access of air may be at first controlled and afterwards prevented. 1175. Coke is obtained from bituminous coal, by a pro- cess analogous to that employed for obtaining vegetable charcoal, which it resembles in chemical, though not in mechanical properties. 1176. Properties. Carbon is inodorous, insipid, and usually black. Charcoal of wood is one of the best radia- tors, and worst conductors of heat. There is reason for believing this peculiarity to result from its excessive poro- CARBON. 221 sity; as in the form of anthracite, carbon conducts heat better, and probably radiates it worse. Charcoal is highly susceptible of galvanic ignition. 1177. Next to the metals, charcoal is the best conductor of electricity. It appears, from the experiments of Pro- fessor Silliman, that charcoal, when exposed to the influ- ence of a powerful Voltaic series, is volatilized, so as to be transferred from the positive to the negative pole, on which it forms a projection. 1178. Charcoal, when intensely ignited without access of air, becomes denser, harder, and a better conductor of heat. Substituting animal products for those of vegeta- tion, in the usual process of carbonization, animal char- coal is obtained. It does not, like the coal of vegetable substances, retain the form of the bodies from which it may be procured, and is replete with cavities, created by the escape of the gaseous elements associated with it in the organic state. It has a grayish-black colour, and a brilliancy resembling that of plumbago. Carbon is preci- pitated in various forms from coal gas; among others, in that of long brittle filaments, associated in tufts, resem- bling locks of hair. 1179. The specific gravity of carbon, in the state of diamond, or in that of common charcoal, when examined in the pulverulent form, so that the result shall not be affected by the numerous cavities existing in it when in mass, is about 3.5. The apparent lightness of charcoal is caused by its porosity. The specific gravity of anthra- cite does not exceed 1.6; that of plumbago is 2.32; yet they are both much more compact than charcoal, and, in proportion to the space occupied by them in mass, ob- viously much heavier. 1180. Carbon, under some circumstances, appears to have a transcendent affinity for oxygen. In its ordinary state it requires a temperature above redness, in order to exhibit this affinity in other words, to burn. In propor- tion as it becomes denser, we find it more difficult to ignite; in proportion as it may be more minutely divided, or approaches a state of extreme porosity, it is rendered more susceptible of ignition. Thus the susceptibility of ignition increases from the diamond to tinder in the fol- lowing order: Diamond, plumbago, anthracite, coke, char- coal of hard wood, charcoal of soft wood, tinder. In some 222 INORGANIC CHEMISTRY. forms, and when mixed with iron, as when obtained by carbonizing Prussian blue, or tanno gullate of iron, it takes fire spontaneously at ordinary temperatures. 1181. According to Despretz, carbon, during its com- bustion, evolves sufficient caloric to melt one hundred and five times its weight of ice. It is not to be inferred that this is true of carbon in all its forms. Berzelius alleges that the same degree of heating power is not possessed by every kind of charcoal; some of its forms, according to him, producing much more heat in burning than others. This I should not believe without conclusive evidence. Of the Decolorizing and Disinfecting Power of Charcoal. 1182. Carbon, as procured from organic products, espe- cially animal matter, displays a great power to combine with and precipitate colouring matters. Hence it is ex- tensively used in the refining of sugar, and generally in chemical processes, in which the objects of research are entangled with colouring matter. This power is not inhe- rent in elementary carbon, but appears to be due to its previous associations, or to some peculiarity of arrange- ment, derived from the process of carbonization. 1183. Animal charcoal is- much more efficacious than that derived from vegetables. The carbonaceous mass, obtained by igniting blood with carbonate of potash, ap- pears to have the greatest efficacy. That the presence of an alkali during the ignition contributes to the effect, seems to justify the conjecture that cyanogen, the generation of which, in combination with the alkali, is a necessary con- comitant, has some agency in the process. Charcoal is a powerful antiseptic, operating efficiently in preserving water or meat from putridity. Moreover, water rendered extremely foul, as that from the public sewers, may be pu- rified by filtration through pulverized charcoal. In fact, filters are now extensively manufactured, in which charcoal is the most efficient and only chemical agent employed. The gravel, sand, and sponge, usually associated with it, act mechanically. Of the Power of Charcoal and other Substances to absorb Aeriform Fluids. 1184. Charcoal, which has, in a state of ignition, been submerged in mercury, on being introduced into gaseous substances, condenses into its CARBON. pores a large quantity of the surrounding aeriform matter, whatever it may be. The quantity condensed varies with the gas, from 90 times the bulk of the charcoal, as in the case of ammonia, to 1.75 times its bulk, as in the case of hydrogen. During their absorption, the gases give out heat, and the more in proportion to the rapidity with which the condensation is effect- ed; and if, on the other hand, by exposure within an exhausted receiver, the gas be evolved, cold is produced. Charcoal, thus deprived of gas, re- absorbs any gas exposed to it, as greedily as if recently ignited. 1185. This faculty of absorbing gaseous substances, is impaired by hu- midity } which charcoal is prone to absorb in the form of vapour, afterwards condensing it into the state of water. Water partially displaces the gases previously absorbed. 1186. The aeriform fluids, absorbed by charcoal, arc expelled by heat unchanged, with the exception of sulphuretted hydrogen and oxygen. The former deposites sulphur, and the latter is gradually converted into carbonic acid. The absorption of this last mentioned principle continues for some time, but, in quantity, has not been found to exceed 14 times the volume of the carbon. In a rarefied medium, charcoal absorbs less in weight, but more in volume; so that the increased resistance of the gas, arising from a diminution of pressure, counteracts, to a certain extent, the power of the coal to condense into its pores a certain weight. The power of absorption varies in a degree with the number and minuteness of the pores existing in the charcoal ; of course, it varies with the wood by which it is yielded. Charcoal of box-wood is pre-eminent in absorbing power; that furnished by woods of a lighter kind is very inferior in this power. Plumbago and anthracite have no capacity, even after ignition, to absorb gases. 1187. In the property of absorbing aeriform fluids, charcoal is not sin- gular. De Saussu re' ascertained that different porous minerals, and many kinds of wood, also silken and woollen stuffs, absorb many times their vo- lume of gas. 1188. When porous bodies are placed in a mixed atmosphere of various gases, they are absorbed in proportion to their reciprocal attractions, and that exercised by the pores of the substances employed. A mixture of oxygen with hydrogen or carbonic acid, is more copiously absorbed than either when alone; yet by heat or exhaustion they are liberated without diminution. Nevertheless, sulphuretted hydrogen and oxygen, when acted upon by charcoal, produce water, sulphur being deposited. 1189. The absorption of moisture by charcoal and other porous bodies has long been noticed. On this account, it is difficult to weigh such bodies without an increase of their weight, even when they are placed in the scale while red-hot. Those aeriform fluids are absorbed to the greatest extent, which are capable of assuming the liquid state. These facts explain the augmentation in weight received by charcoal exposed to the air, which amounts to between ten and twenty per cent. 1190. I have devoted more space to this subject, because it illustrates a property which otherwise might not be sufficiently considered. It forms a peculiar instance of mechanico-chemical agency, if I may be allowed to use a new word to express the idea. Without the porous or cellular struc- ture which it possesses in the form of charcoal, carbon is not endowed with either disinfecting, absorbing, or colour-removing powers; and yet it is evident that the carbon acts in charcoal by a species of chemical af- finity, unaided by which the cellular structure would be inefficient in the processes under consideration. As respects the transmission of contagious 224 INORGANIC CHEMISTRY. or infectious effluvia, the absorbing power of porous bodies merits attention. I believe that the carbonaceous matter, evolved during the burning of sugar, actually neutralizes those fetid emanations which it is employed to correct in the chambers of the sick. COMPOUNDS OF CARBON WITH OXYGEN. with one atom or half a volume of oxygen, One atom or one volume of carbon, equivalent 6, equivalent 8, forms one atom or one volume of carbonic oxide, equivalent 14. with two atoms or one volume of oxygen, equivalent 16, forms one atom or one volume of carbonic acid, equivalent 22. 1191. Two atoms or volumes of carbon, equivalent 12, with three atoms or one and a half, volumes of oxygen, equivalent 24, form one atom of oxalic acid, equivalent 36. 1192. Two other compounds of carbon with oxygen are alleged to exist; one called mellitic, the other croconic acid. The former contains four atoms of carbon to three of oxy- gen; the latter five of carbon to four of oxygen. Of Carbonic Oxide. 1193. Preparation. This compound is produced by the combustion of carbon with an inadequate supply of oxy- gen; or when bodies containing carbonic acid are heated with certain substances having an affinity for oxygen. Thus it may be procured by heating carbonate of lime with iron filings. The best process, however, for obtain- ing carbonic oxide in a state of purity, is to heat five parts of concentrated sulphuric acid with one of oxalic acid; which, being deprived by the sulphuric acid of the water which is essential to its existence, is resolved into car- bonic oxide and carbonic acid. The latter gas may be removed by lime-water, leaving the carbonic oxide in a state of purity. Apparatus for separating Carbonic Acid from Carbonic Oxide, oy means of Lime-water. 1194. This apparatus is represented by the opposite engraving. Lime-water being introduced in sufficient quantity into the inverted bell glass, another smaller bell glass, C, is supported within it as represented in the engraving. Both of the bells have perforated necks. The inverted bell is furnished with a brass cap having a stuffing box attached to it, through which the tube, D, of copper, slides air-tight. About the lower end of this tube, the neck of a gum elastic bag is tied; so that the cavity of the bag may communicate with that of the tube. The neck of the other bell is furnished with a cap and cock, surmounted by a gallows screw, by means of which the leaden pipe, P P, with a brass knob at the end suitably perforated, may be fastened to it, or removed at any moment. Suppose this pipe, by aid of another brass knob at the other extremity, to be attached to the perforated neck of a very tall bell glass filled with water upon a shelf of the pneumatic cistern : on opening Apparatus for separating Carbonic Acid from Carbonic Oxide, by Means of Lime-water. (Page 224.) CARBON. ' 225 a communication between the bells, the water will subside in the tall bell glass over the cistern, and the air of the bell glass, C, being drawn into it, the lime-water will rise into and partially occupy the space within the latter. As soon as this is ef- fected, the cocks must be closed, and the tall bell glass replaced by a small one filled with water, and furnished with a gallows screw and cock. This bell being at- tached to the knob of the lead pipe, to which the tall bell had been fastened before, the apparatus is ready for use. I have employed it in the new process for obtaining carbonic oxide from oxalic acid, by digestion with sulphuric acid in a glass retort. The gaseous product consists of equal volumes of carbonic oxide and carbonic acid, which, being received into a bell glass, communicating, as above described, by a pipe with the bell glass, C, may be transferred into the latter, through the pipe, by open- ing the cocks. As the gaseous mixture enters the bell, C, the lime-water subsides. As soon as a sufficient quantity of the gas has entered, the gaseous mixture, by means of the gum elastic bag and the hand, may be subjected to repeated jets of lime-water, and thus depurated of all the carbonic acid. By raising the liquid in the outer bell, A, the purified carbonic oxide may be propelled through the cock and lead pipe, into any vessel to which it may be desirable to have it transferred. 1195. Properties of Carbonic Oxide. Carbonic oxide is a colourless, insipid gas, indecomposable by heat or elec- tricity, and incapable of reddening litmus. Its specific gravity is 0.9727. It does not support combustion, and is destructive to life. It burns with a feeble blue flame, and, combining with oxygen, is converted into carbonic acid. By platinum sponge, a mixture of oxygen and carbonic oxide is gradually changed into carbonic acid. Experimental Illustrations. 1196. Carbonic oxide gas, evolved from oxalic acid by the process abovementioned, and collected in bell glasses over water. Combustion and detonation of it with oxy- gen gas, effected by means of a sliding-rod eudiometer, or volumescope. Subsequent absorption of the resulting car- bonic acid by lime-water, shown. Of Carbonic Acid. 1197. The proportion of this gas, existing in the atmos- phere, is much less than was formerly supposed ; being, ac- cording to some experiments of Thenard, not more than a thousandth part. It is this portion, however, that pro- duces the pellicle on lime-water, during its exposure to the air, and which, under like circumstances, by combining with the alkalies, enables them to effervesce with acids. Carbonic acid is incessantly a product of combustion and of the respiration of animals. It is a principal ingredient in marble and limestone. 1198. Preparation. Carbonic acid may be evolved from 29 226 INORGANIC CHEMISTRY. any carbonate by heat or by acids. It is usually procured for the impregnation of water, by the superior affinity of sulphuric acid for the lime in marble. Excepting that it is more costly, chlorohydric acid is preferable for this pur- pose; as the chloride of calcium, being very soluble, does not, like the sulphate, clog the vessels. 1199. Carbonic acid is evolved copiously during the vi- nous fermentation. 1200. The process and the self-regulating reservoirs, already described, (796, &c.) may be resorted to for car- bonic acid, substituting lumps of marble for zinc. The best materials for the evolution of this gas, agreeably to my experience, are chlorohydric acid and calcareous sta- lactites, or clam shells. 1201. Carbonic acid might be procured at a trifling cost, by drawing, by the aid of a suction pump, the efflu- vium of burning charcoal through water to deprive it of dust, and then forcing it into the cavities in which its pre- sence may be desirable. 1202. This process for the production and employment of carbonic acid, generated by the combustion of charcoal, is illustrated in the small way by the following engraving and description. Combustion of Charcoal or other Combustibles in Oxygen Gas. 1203. The preceding cut represents an apparatus which I have contrived for ex- hibiting the combustion of charcoal, or other combustibles, in oxygen gas. Two large glass bells. A, B, each furnished with a tubulure at the apex, are associated by CARBON. 227 means of the pipe, P, which, in one of the bells, B, communicates with a tube, ex- tending about five inches within the bell, below its neck, so as to reach into some lime-water, or an infusion of litmus, contained in a glass vessel, resting on a stand, as represented in the figure. The wooden stand which holds the glass vessel, and the iron stand which supports the coal in the bell, A, must be previously placed on (he shelf of the pneumatic cistern, as represented in the cut; so that A, when in- cluding the coal, may be over the mouth of the cock, D, which communicates with one of the gas holders, situated under the shelves of the pneumatic cistern, which, for this experiment, should be filled with oxygen. 1204. Into the bell glass in which the vessel is placed, a pipe from the suction pump of the hydrostatic blowpipe is made to enter, and reach nearly to the stand. The apparatus having been prepared thus far, the bells must be lifted so as to permit a live coal to be put upon the iron stand, as represented in the figure. As soon as they are restored to their previous situations, the suction pump must be put into operation, and the cock, D, of the gas holder, containing the oxygen, opened; so as to allow a current of the gas to have access to the coal, by replacing the air, which is withdrawn by the pump through the pipes, P and E. The coal burns splendidly; and as the oxygen becomes saturated, it is drawn off by the suction pump, being made, in its way from A to B, to pass through the liquid in the vessel, into which descends the tube proceeding from A. If the liquid be water tinged with litmus, it will become red by the action of the carbonic acid : if it be lime-water, a copious milky precipitate will appear. 1205. Properties of Carbonic Acid. It is a colourless gas, with a pungent smell and an acid taste. Water takes up its own bulk of this gas, whatever may be its density. It combines with earths, alkalies, and metallic oxides, form- ing with lime, baryta, strontia, magnesia, and oxide of lead, compounds which are insoluble. Hence it precipi- tates lime-water, barytic-water, and solution of acetate of lead. Litmus is reddened by this acid. It destroys life and extinguishes flame, but is not insalubrious to breathe when much diluted with air. 1206. Carbonic acid is very antiseptic. When concen- trated in water it is grateful to the stomach. Potassium burns in this gas, absorbing oxygen and precipitating car- bon. Plants probably absorb it, retain its carbon, and give out its oxygen. The respiration of animals tends to compensate this change, by carbonizing the oxygen of the air. 1207. Carbonic acid is heavier than atmospheric air, its specific gravity being 1,5239. At the temperature of 32, and under a pressure of forty atmospheres, it con- denses into a colourless liquid. Experimental Illustrations. 1208. Evolution of the gas shown; also its property of extinguishing a candle. That it differs from nitrogen, made evident by means of lime-water. Litmus, reddened by carbonated water, and restored to its original colour by boiling. 228 INORGANIC CHEMISTRY. 1209. Analysis of mixtures containing the gas, by means of the sliding-rod eudiometer and lime-water. Apparatus for shoioing some of the distinguishing Properties of Carbonic Add Gas. 1210. Having introduced into the three-necked bottle, represented in the adjoining figure, one or two ounces of carbonate of ammonia, add about half as much nitroso-nitric acid. (1017.) An active effervescence will ensue, arising from the expulsion of the carbonic acid from the ammonia, by the stronger af- finity of the nitric acid. At the same time, sufficient fume will be generated to make it evident how far the vessels are occupied by the gas, to the exclu- sion of atmospheric air. By these means the movements of the carbonic acid gas will be recognised as ascending to the upper vessel, which it will fill, and finally overflow through the crevice be- tween the brim and cover. 1211. The cover being removed, a lighted candle will cease to burn, when lowered into the fume indicating the space occupied by the gas. This space will comprise the whole cavity of the vessel, so long as the aperture, A, is closed ; but, on removing the cork from this aperture, the gas will flow out, and the stream, marked by the accompany- ing fume, will be seen descending to- wards the table, and will extinguish the flame of a candle if made to encounter it; or, it may be received into a mug, so as to arrest the combustion of a taper introduced into it, or upon which the con- tents of the mug may be poured. Under these circumstances, a taper will burn any- where within the vessel, V, if it be not below the aperture, A, above which the gas is not now seen to extend itself. But if one of the orifices of the bottle be opened, the carbonic acid will be found entirely to desert the upper vessel. 1212. It will thus be made evident that this gas, from its greater specific gravity, has, in the atmosphere, some of the habitudes of liquids ; while its incapacity to support combustion will be demonstrated. 1213. The specific gravity of carbonic acid being rather more than one-half greater than that of atmospheric air, it does not speedily leave any cavity in which it may be introduced. It is on this account that persons often perish on entering wells. Impregnation of Water with Carbonic Add. 1214. The process by which water is impregnated with carbonic acid, may be easily understood from the following engraving. 1215. A condenser, A, is fastened at bottom into a block of brass, which is fur- nished with a conical brass screw, by means of which it is easily attached firmly to the floor. In this brass block are cavities for the two valves, one opening inwards from the pipe, B, the other outwards towards the pipe, C. The pipe, B, commu- nicates with a self-regulating reservoir of carbonic acid. 1216. The gas which the condenser draws in from the reservoir, is forced through the other pipe into a strong copper vessel, in which the water is situated, and which is represented in the figure, as if the front part were removed, in order to expose the inside to inspection. 1217. If the vessel and its contents be thoroughly exhausted of air before the im- pregnation is commenced, the water will take up as many times its bulk of gas, as the pressure employed exceeds that of the atmosphere. 1218 When duly saturated, the water may be withdrawn nt. pleasure by means of CARBON. 229 the syphon, D, of which one leg descends from the vertex of the vessel to the bot- tom, while the other is conveniently situated for filling a goblet. Of the Liquefaction and Solidification of Carbonic Add. 1219. It has been shown that the extrication of carbonic acid from a base, may be checked by the pressure consequent to confinement, (242,) and it has been mentioned that Faraday obtained this acid in a liquid state, by causing the materials for the generation of it to react within a glass tube, sealed her- metically after their introduction. Subsequently, the liquefaction of this acid was accomplished on a much larger scale by Brunei; and in 1836, thirteen years after the date of Faraday's observations, Thillorier caused not only the liquefaction, but the solidification of the acid. Without any other knowledge than that afforded by brief notice, or verbal information con- veyed by travellers, my friend, Dr. Mitchell, was quite successful in the repetition of the processes of Thillorier. The production of the solid acid is dependent on the same principles as the congelation of water in the cryo- phorus and in Leslie's experiment. (309, &c.) 1220. The pressure requisite to retain carbonic acid in a state of liquidity, is at 4 below zero, 26 atmospheres; at 32, 36 atmospheres; at 86, 75 atmospheres. (196.) Its specific gravity is, at that temperature, about 830. The density of the gas which occupies the cavity above the liquid portion of the acid, is 130 times the density of that which it has at the mean baro- metric pressure of 30 inches of mercury. 1221. Liquid carbonic acid does not combine, nor even mingle, with water or fixed oils; but, under the requisite pressure, combines readily with ether, alcohol, naphtha, or oil of turpentine. It may be decomposed by potassium, but not by zinc, iron, or other metals proper. 1222. One of the most interesting properties of the acid, is that intense cold produced by its assuming the aeriform state, to which allusion has been made. A jet of it depressed a thermometer to 130 below zero, F. The cold by which the acid is frozen, or in other words, its freezing point, is estimated at 148 below zero, F. According to Mitchell, one drachm of 230 INORGANIC CHEMISTRY. solid acid is yielded by each ounce of the liquid. I will here give Dr. Mitchell's description of this wonderful product of chemical art, in his own words :* 1223. " The porosity and volatile character of the solid renders its specific gravity of difficult ascertainment. When recently formed it is about the weight of carbonate of magnesia, and when strongly compressed by the firigers, its density is nearly doubled. Solid carbonic acid is of a perfect whiteness, and of a soft and spongy texture, very like slightly moistened and aggregated snow. It evaporates rapidly, becoming thereby colder and colder; but the coldness produced seems to steadily lessen the evaporation, so that the mass may be kept for some time. A quantity weighing 346 grains lost from 3 to 4 grains per minute at first, but did not entirely dis- appear for 3 hours and a half. The natural temperature was 76 79. The solid is most easily kept when compressed and rolled up in cotton or wool. Its temperature when newly formed is not exactly ascertainable be- cause it is immediately lowered by evaporation. Thillorier seems to have entertained the opinion that the greatest degree of cold was created at the time of the formation of the solid. In my experiments a constant decrease of temperature was observed ; which was accelerated by a current of air, or any other means of augmenting evaporation. At its formation, the car- bonic snow depresses the thermometer to about 85. If it be confined in wool or raw cotton, its cooling influence is retarded ; if it be exposed to the air, especially when in motion, the thermometer descends much more rapidly ,* and under the receiver of an air pump, the effect is at its maxi- mum. The greatest cold produced by the solid carbonic acid in the air was 109, under an exhausted receiver 136, the natural temperature be- ing at + 86. 1224. " The admixture of sulphuric ether so as to produce the appearance of wet snow, increased the coldness, for the temperature then fell, under exhaustion, to 146,* a degree of cold which we were not able to exceed by means of any variation of the experiment. That result is most easily obtained by putting about two fluid drachms of ether into the iron receiver before charging it. A compound liquid may be thus formed which yields a snow in less quantity, but of a more facile refrigeration. Alcohol may replace ether in either mode, but with less decided effect. In the air the alcoholic mixture fell to 106 and remained stationary. By blowing the breath on it, it fell to -110. Left to itself it rose slowly to 106 ; but on being placed under an exhausted receiver fell to 134. 1225. " Every attempt to wet the carbonic solid with water, failed, so that no estimate of its relative effects could be made. 1226. " The experiments resulting from the great coldness of the new solid, were very striking. Mercury placed in a cavity in it, and covered up with the same substance, was frozen in a few seconds. But the solidifica- tion of the mercury was almost instantly produced by pouring it into a paste made by the addition of a little ether. Frozen mercury is like lead, soft and easily cut. It is ductile, malleable, and insonorous. Just as it is about to melt, it becomes brittle or ' short' and breaks under the point of a knife. These facts may account for the discrepancies of authors on this subject. Frozen mercury sinks readily in liquid mercury. 1227. " At about 110 liquid sulphurous acid is frozen, and the ice * For engraving and description of Mitchell's modification of Thillorier's appara- tus, see Appendix. CARBON. 231 sinks in its own liquid, and at 130 alcohol of .798, assumes a viscid and oily appearance, which by increase of cold, is augmented until at 146 it is like melted wax. Alcohol of .820 froze readily. At 146 sulphuric ether is not in the slightest degree altered. 1228. "When a piece of solid carbonic acid is pressed against a living animal surface, it drives off the circulating fluids and produces a ghastly white spot. If held for 15 seconds it raises a blister, and if the application be continued for two minutes a deep white depression with an elevated mar- gin is perceived ; the part is killed, and a slough is in time the consequence. I have thus produced both blisters and sloughs, by means nearly as prompt as fire, but much less alarming to my patients." Of Oxalic Acid, 1229. Latterly oxalic acid, long known as a product of vegetation, has been found to belong to the compounds of carbon with oxygen ; and still more lately mellitic and cro- conic acid have been added to this class. Yet when the necessity of water to the existence of these acids is taken into view, it appears to rne questionable whether they may not be considered as acids with a compound radical, con- sisting of hydrogen and carbon. 1230. Preparation. Oxalic acid may be obtained from the common sorrel, Rumex acetosa, or from the wood sorrel, Oxalis acetosella, from which it derives its name. In these plants it exists in the state of binoxalate of potash. It may also be procured by the reaction of one part of sugar with six of nitric acid. The weight of the acid obtained is equal to three-eighths of the materials. Wood, glue, silk, or hair may be substituted for sugar in this process ; but when these substances are used, the product is impure. Next to sugar, starch and molasses are probably the best materials. Oxalic acid may be procured also, by digesting shavings of wood in a solution of caustic potash, at a heat considerably above that of boiling water. 1231. Properties. Oxalic acid is a solid, but soluble both in water and alcohol, the resulting solutions being extremely sour. One grain in half a pint of water is sufficient to redden litmus distinctly. It cannot exist uncombined with water or some other base. The atomic composition of this acid would authorize us to consider it as a binary compound of carbonic acid and carbonic oxide. In every atom of oxalic acid in its appropriate crystalline form, there are three atoms of water. When these crystals are exposed to an unusually dry atmosphere, or to a tempera- ture of 80, a partial efflorescence ensues ; and if the heat 232 INORGANIC CHEMISTRY. be raised to 212, they part with two atoms of water, which they recover on exposure to the air after cooling. When heated to 300, the acid is decomposed. 1232. Oxalic acid is an energetic poison. The best an- tidotes for it are magnesia, or the calcareous carbonates in the pulverulent form, especially chalk. When oxalic acid meets with either of these bases, an insoluble and inert oxalate is formed. Hence its employment as a test for lime. 1233. It appears from statements made by Vogel in the Journale de Pharmacie, for April, 1836, that the protoxides of iron and copper are precipitated from their union with sulphuric acid by oxalic acid. The oxalate of iron is yel- low; the oxalate of copper, blue. Both are insoluble in water. Of Mellitic Acid. 1234. Mellitic acid is obtained in crystals from a rare mineral, called the honey-stone, which is a mellitate of alumina. It is soluble in water and alcohol, and has a sour taste. Of Croconic Acid. 1235. Croconic acid may be procured in yellow crystals, from the croconate of potash, which is generated in the pro- cess for obtaining potassium by means of charcoal. It is inodorous, has an acid and astringent taste, and reddens litmus. COMPOUNDS OF CARBON WITH OXYGEN AND CHLORINE. 1236. There are two compounds of carbon with oxygen and chlorine. To one of these, which has been recently discovered, the name of chloral has been given ; to .the other, that of chlorocarbonic or chloroxycarbonic acid. The latter name is preferable; as the other would convey the idea of an acid made solely by the union of chlorine with carbon. Of Chloral. 1237. When chlorine is passed through alcohol, which consists of hy- drogen, oxygen, and carbon, one portion combines with hydrogen, forming chlorohydric acid, while another combines with oxygen and carbon, form- ing chloral. 1238. Chloral is described as a colourless transparent liquid with a pun- gent odour. Its specific gravity is 1.502. It boils at 201, and may be distilled unchanged. With water it forms a white crystalline mass, appa- rently a hydrate. CARBON. 233 1239. Chloral consists of nine atoms of carbon, four of oxygen, and six of chlorine. Of Chloroxy carbonic Acid. 1240. When one volume of dry chlorine and one volume of carbonic oxide gas are mingled, and exposed to the solar rays, they combine, and condense into one volume of a colourless acid gas, to which the name of chloroxycarbonic acid has been given. It is exceedingly offensive to the eves and to the organs of respiration. It reddens litmus paper, and with ammonia forms a white salt. By contact with water a reciprocal decom- position ensues, and chlorohydric and carbonic acids are produced. It con- sists of one atom of chlorine, and one atom of carbonic oxide. Of the Chlorides of Carbon. 1241. Chlorine forms four compounds with carbon. The dichloride is a white crystalline inflammable solid, having a peculiar odour, resembling that of spermaceti. At 250 it sublimes in crystals. It is fusible by heat, and boils at a temperature between 350 and 450. The dichloride con- sists of one atom of chlorine and two of carbon. 1242. When the liquid, produced by the union of chlorine with olefiant gas, called bichlorine ether, is exposed to the sun, in contact with a suffi- cient quantity of chlorine, the sesqitichloride of carbon is produced. It is a colourless, transparent, friable, crystalline body, nearly tasteless, and re- sembling camphor in smell. While exposed to the flame of a spirit lamp, it burns with a red flame, but the combustion ceases as soon as the lamp is removed. It melts at 320, and at 360 is converted into vapour, which may be condensed without decomposition. It is nearly twice as heavy as water. The sesquichloride of carbon consists of three atoms of chlorine and two atoms of carbon. 1243. The protochloride is obtained by passing the sesquichloride in vapour through a red-hot porcelain tube. The sesquichloride is decom- posed into the protochloride and chlorine. The protochloride is a transpa- rent, colourless liquid, with a specific gravity of 1.4875. It is composed of one atom of chlorine and one of carbon. 1244. All the above described chlorides are insoluble in water, acids, and alkalies; but are soluble in oils, alcohol, and ether. When chloral is boiled in a solution of potash, a decomposition ensues, and a chloride of carbon is evolved in vapour, and may be condensed in a receiver. This chloride is a colourless, transparent liquid, with an odour similar to that of chloric ether. Its specific gravity is 1.48. This chloride consists of five atoms of chlorine and four of carbon. Of Bromide of Carbon. 1245. When bromine is brought in contact with half its weight of per- iodide of carbon, heat is evolved, a decomposition ensues, and bromides of iodine and carbon are formed. The bromide of carbon is a volatile, colour- less liquid, of a sweet taste, and an ethereal odour. Of the Iodides of Carbon. 1246. The protiodide of carbon is a liquid, in properties strongly re- sembling the bromide of carbon. The periodide appears under the form 30 234 INORGANIC CHEMISTRY. of yellow crystalline scales, which have a sweet taste, a strong aromatic smell resembling that of saffron, and a specific gravity higher than that of water. Of Sulphocarbonic Acid, or Bisulphide of Carbon. 1247. The bisulphide of carbon is obtained by passing the vapour of sulphur over charcoal heated to incandescence in a porcelain tube. It is a transparent, colourless, volatile liquid, possessing an acrid taste, and a pecu- liar nauseous smell. Its specific gravity is 1.272. It boils at 105, and does not freeze at 60. At a temperature a little above the boiling point of mercury, it inflames. When the bulb of a spirit thermometer, wrapped in lint imbued with this liquid, is placed within a receiver, and the air witfc' drawn, the temperature falls to 82. 1248. This compound unites with almost all the sulpho-bases, forming with them sulpho-salts, and is as well entitled to be treated as an acid, as the analogous compound formed by sulphur with hydrogen. 1249. Dr. Thomson supposes that the solid mass, obtained by washing the nitre out of gunpowder, is probably a solid sulphide of carbon. COMPOUNDS OF CARBON WITH HYDROGEN. 1250. Carbon and hydrogen are in opposite extremes, as respects their susceptibility of the aeriform state. Per se, carbon is probably more difficult of volatilization by heat, than any other substance in nature. Hydrogen, on the other hand, as far as our experience goes, is not sus- ceptible of condensation, even into the non-elastic state of fluidity. There is, however, a powerful affinity between these substances; and hence, when a compound which contains them is subjected to heat, they are made to combine in various proportions, according to the intensity of the ignition, and the influence exercised by the nitro- gen, or oxygen, previously in combination with them. 1251. In general, the compounds of carbon with hydro- gen are distinguished by inflammability. In the gaseous state they constitute, when ignited, the flame of candles, lamps, gas lights, and culinary fires. They are incapable of supporting life, but are not actively noxious when di- luted with the air. 1252. The gaseous compounds of carbon with hydrogen are obtained by the destructive distillation of bituminous coal, wood, oil, tar, and other inflammable substances. 1253. The illuminating power of each of these various kinds of gas, seems to be in proportion to the quantity of carbon contained in a given volume, provided there be an equivalent supply of oxygen ; but, otherwise, the excess of carbon renders the flame smoky. Hence the greater bril- CARBON. 235 liancy of small flames, or those excited by a current of air, as in the Argand lamp. The same flame which in common air is unpleasantly fuliginous, transferred to oxy- gen gas, displays a perfect brilliancy. 1254. The known compounds of carbon with hydrogen are numerous and complicated ; and yet it is probable that many exist in nature, or may be produced by art, with which we are at present unacquainted. 1255. We have had occasion to state, (1153,) that where bodies have, in the same volume, the same number of atoms of each of their ingredients, and yet differ in their properties, they are said to be isomeric, from to-eg equal, pspoi; part. Compounds, in which the constituents are in the same ratio, but in which the resulting volumes exist in different degrees of con- densation, are said to be polymeric with respect to each other, from notes many, pupos part. The last term is applied to a class of the compounds of carbon with hydrogen, in all of which these elements exist in the same ratio of atom for atom ; yet from some difference in the mode of aggregation, or, as I believe, in the extent and modes of their association with heat, light, and electricity, their degree of condensation when in the aeriform state, and their properties in other respects are quite different. 1256. We have then two groups of the carburets of hydrogen, in one of which diversity of properties is attended by a corresponding diversity in the ratio of the carbon to the hydrogen; while in the other this ratio is uni- form, although the properties and resulting volumes in the aeriform state, differ. In the first group, there are four compounds. 1257. 1. Light carburetted hydrogen, or fire damp, consisting of two volumes or atoms of hydrogen, with one volume or atom of carbon. 1258. 2. The compound, in all the varieties of which there are as many atoms of one element as of the other, and for which Dr. Thomson proposes the name of carbohydrogen as a generic appellation. 1259. 3. By carburet of hydrogen, in which six atoms of carbon are united with three of hydrogen. 1260. 4. Naphthaline, in which ten atoms of carbon are combined with four atoms of hydrogen. 1261. The second group, which is subordinate to the first, being formed in fact by the ramifications of carbohydrogen, comprises, according to Dr. Thomson, several varieties, which he designates and describes as follows : 1262. 1st. Protocarbohydrogen, consisting of a volume of carbon and a volume of hydrogen, condensed into one volume. This variety, now called mytheline, has been lately isolated by Dumas and Peligot, by distil- ling one part of pyroxylic spirit, obtained by the distillation of wood, with two parts of chlorohydric acid, and three of sulphuric acid; when an ethe- real chlorohydrate of mytheline results. Subjected to a red heat, this ethe- real compound is resolved into chlorohydric acid gas, and mytheline in the gaseous form. Pyroxylic spirit is considered as a bihydrate of mytheline, being procured from crude pyroligneous acid by distillation. It bears the same relation to mytheline that alcohol docs to ethcrinc. (1267.) 1263. 2d. Dcntocarbohydrogen, or olejiant gas, consisting of two vo- lumes of carbon and two of hydrogen, condensed into one volume, 1264. 3d. Tritocarbohydrogen, consisting of three volumes of carbon 236 INORGANIC CHEMISTRY. and three of hydrogen, condensed into one volume. This is by Dr. Thom- son considered as constituting the gas evolved from oil, which was by Dai- ton called super-olefiant gas. 1265. 4th. Tetartocarbohydrogen, consisting of four volumes of car- bon, and four volumes of hydrogen, condensed into one volume. 1266. 5th. Hexacarbohydrogen, containing, according to Thomson, six volumes of each element, condensed into one volume. 1267. Of Ether ine. Besides these compounds, it has been inferred, by many chemists, that there is a liquid, or solid compound, formed of four volumes or atoms of carbon, and four volumes or atoms of hydrogen, con-^ densed into one volume or atom. This has been called etherine, under the idea that it is the common base of all the ethers, forming common ether by uniting with one volume of aqueous vapour, alcohol, by uniting with two such volumes, and the various ethers, by uniting with acids, or the other in- gredients, after which they are severally named. Etherine would of course beisomeric with the tetartocarbohydrogen of Dr. Thomson. (1265.) Of Light Carburetted Hydrogen, or Fire Damp. 1268. The substance distinguished by these names has been dignified by a variety of appellations, among which are heavy inflammable air, car- buretted hydrogen, and bihydroguret of carbon. Dr. Thomson has, in some instances, used the monosyllable di to indicate proportions the inverse of those indicated by the monosyllable bi. Thus, bichloride of carbon would signify two atoms of chlorine and one of carbon, while dichloride conveys the idea of two atoms of carbon and one of chlorine. Consistently, then, I think, Dr. Thomson should have called this gas, a dicarburet of hydrogen; as the proportions of its constituents are the inverse of those in the bicarbu- ret. This gas has long been known to miners of bituminous coal, under the name of fire damp, as one of their greatest enemies. It is liberated co- piously from cavities in the coal, in which, no doubt, in many instances, it has been pent for ages. It is also evolved from the mud of stagnant waters, and is occasionally emitted from fissures in the earth. There is no good mode of forming it artificially. It is a colourless gas, of course irrespirable, but having more than a negative influence in destroying life. Its specific gravity is 0.5593. Of the Safety Lamp. 1269. In the account above given of dicarburet of hydrogen, it was mentioned that it was in mines a source of injury. When existing in the air beyond a certain pro- portion, it explodes on coming into contact with the flame of a lamp or candle. Hence, as artificial light is necessary in mines inaccessible to the light of day, the use of candles or lamps, in the ordinary way, has been frequently destructive to the workmen. It had, of course, been the cause of great misery to them, and of em- barrassment to the proprietors of the mines. 1270. In order to avoid the risk attending the use of lamps or candles in mining, a "steel mill" had been resorted to, in which the rapid revolution of a steel wheel against a flint, was made to produce a succession of sparks, and of course a feeble light. I believe that the security afforded by this invention was imperfect, and the light in- sufficient. Explosions have been more frequent in the English mines of late years, probably in consequence of the greater extent and depth to which they are excavated. While under the painful impression made by some recent catastrophes of this nature, in which many miners had been been killed or mutilated, Sir H. Davy exerted him- self to discover the means of sustaining flame safely within explosive gaseous mix- tures. He soon ascertained that his object might be effected by enclosing the flame in a cage of wire gauze, so as to allow of no communication with the surroundino- medium, which does not take place through the meshes of the gauze. Owing to the CARBON. 237 cooling power of the wire, the mixture cannot pass through the meshes in a state of combustion. Of course the inflammation is confined within the wire gauze. 1271. The method in which I illustrate the operation of the safety lamp, may be easily comprehended from the following figure. The lamp is seen within a large glass cylinder upon a stool. The cy- linder is closely covered by a lid, which will not permit the passage of air between it and the cylinder, and which is so light as to be easily blown oiF. Excepting the cage alluded to above, the safety lamp does not dif- fer materially from those which are ordinarily used. The upper surface of the receptacle for the oil, forms the bottom of the cage, which is so closely fitted to it, and so well closed every where, as to allow air to have access to the flame only through the meshes of the wire gauze. The cage is enclosed within three iron rods, surmounted by a cap, to which a ring for holding the lamp is attached, as seen in the figure. 1272. If, while the lamp is burning, as represented in the figure, hydro- gen, either pure or carburetted, be allowed, by means of the pipe, to en- ter the glass cylinder, so as to form with the air in it an explosive mix- ture, there will nevertheless be no explosion. It will be found that as the quantity of inflammable gas in- creases, the flame of the lamp en- larges, until it reaches the wire gauze; where it burns more or less actively, accordingly as the supply of atmospheric air is greater or less. It will, under these circumstances, often appear as if the combustion had ceased; but on increasing the proportion of atmospheric air, the flame will gradually contract, and finally settle upon the wick, which will burn as at first when the supply of hydrogen ceases. 1273. If the cage be removed from the lamp, and the experiment repeated in all other respects as at ffrst, an explosion will ensue, as soon as a sufficient quantity of hydrogen is allowed to enter the cylinder. Of Deutocarbohydrogen, or Olefiant Gas, called also Carbu- retted Hydrogen, and Hydroguret of Carbon. 1274. This gas received its name in consequence of its being condensed with chlorine into a liquid, having an oleaginous consistency, although otherwise unlike an oil. It was discovered in the year 1796. It may be obtained by subjecting a mixture of five parts of sulphuric acid with one of alcohol to heat in a glass retort. It is invisible, and possesses, like other gases, the mechanical properties of atmospheric air. Its specific gravity is 0.9808. When drawn into the lungs it produces asphyxia. It burns with great splendour, and detonates with oxygen with such vio- lence, that without some precautions it is dangerous to 238 INORGANIC CHEMISTRY. analyze it by the usual processes. I have had several eudiometers broken by it, but have latterly avoided that accident, by exploding the mixture in a rarefied state, into which it is easily brought in some of the instruments which I employ. 1275. The analysis may be performed in the volume- scope for analyzing the air by means of hydrogen, with a degree of "accuracy sufficient for the purpose of illustra- tion. Four volumes of oxygen should be added to one of the gas. The ignition being effected as already described in the case of pure hydrogen, it will be seen that the five volumes are reduced to less than three, and that by the introduction of lime-water, these three may be reduced to one residual volume of oxygen. The reason why the re- sidual gas is less than three volumes, is, that the carbonic acid formed is partially absorbed by the water. As the gas contains in one volume, two volumes of hydrogen, and two of carbon vapour, it will, for the latter, require two volumes; for the former, one volume of oxygen. Of course the hydrogen, and the oxygen which combine with it, will be condensed; so that after the explosion, unless so far as absorbed by the water, two volumes of carbonic acid will remain mingled with the one volume of oxygen in excess. Of certain Gaseous Compounds formed by igniting the Gaseous Elements of Water ', while containing Olefiant Gas, or the Vapour of Ethers, or Essential Oils. 1276. I observed some years ago, that when olefiant gas is inflamed with an inadequate supply of oxygen, carbon is deposited, so copiously as to ren- der the glass receiver of the eudiometer impervious to light, while the result- ing gas occupies double the space of the mixture before explosion. Of this I conceive I have discovered the explanation. By a great number of expe- riments, performed with the aid of my barometer-gauge eudiometer, I have ascertained that if during the explosion of the gaseous elements of water any gaseous or volatile inflammable matter be present, instead of condensing there will be a permanent gas formed by the union of the nascent water with the inflammable matter. Thus two volumes of oxygen, with four of hydrogen, and one of olefiant gas, give six volumes of permanent gas, which burns and smells like light carburetted hydrogen. The same quan- tity of the pure hydrogen and oxygen, with half a volume of hydric ether, gives on the average, the same residue. One volume of the new hyponi- trous ether, under like circumstances, produced five volumes of gas. 1277. An analogous product is obtained when the same aqueous ele- ments are inflamed in the presence of an essential oil. With oil of turpen- tine a gas was obtained, weighing, per hundred cubic inches, 16 T 5 F grs., which is nearly the gravity of light carburetted hydrogen. The gas ob- tained from olefiant gas, or from ether, weighed on the average, per the CARBON. 239 same bulk, 13^ grs. The olcfiant gas which I used, weighed per hun- dred cubic inches, only 30-^ grs. Of course, if, per se, expanded into six volumes, it could have weighed only one-sixth of that weight, or little over five grains per hundred cubic inches. There can, therefore, be no doubt that the gas obtained by the means in question is chiefly constituted of water, or of its elements, in the proportion in which they exist in that liquid. See table, page 189, for steam. 1 278. The gas created in either of the modes abovementioned does not contain carbonic acid, and when generated from olefiant gas, appears by analysis to yield the same quantity of carbon and hydrogen as that gas affords before expansion. 1279. These facts point out a source of error in experiments, for ana- lyzing gaseous mixtures by ignition with oxygen or hydrogen, in which the consequent condensation is appealed to as a basis for an estimate. It appears that the resulting water may form new products with certain vola- tilizable substances which may be present. 1280. The gas obtained by passing the vapour of alcohol through an ignited porcelain tube, is confounded generally with that which results from the reaction of sulphuric acid with alcohol, as above described, (1273,) but equal volumes of the gaseous products obtained, the two processes being analyzed, I found that procured by ignition to have only condensed half as much oxygen as the other. From the facts above stated, that the presence of water causes a union between its elements, and those of the carbon and hydrogen of carburets, whether in the form of vapour or gas, it may be in- ferred that the products of the decomposition of alcohol must vary accord- ingly as it may be more or less anhydrous. The alcohol which I employed was of the specific gravity nearly of 840: were absolute alcohol subjected to the process in question, a gas containing a larger proportion of carbon might be obtained. (619, 1252.) Experimental Illustrations. 1281. Cork, cotton-seed, caoutchouc, and nuts, intro- duced in small quantities into a gun-barrel, of which the butt-end has been heated to a bright red-heat. Brilliant jet of flame proceeds from the touch-hole. Inflammation of the gas extricated by distillation from oil or bituminous coal, also of olefiant gas. Olefiant gas, mixed with oxygen gas, and exploded in a sliding-rod eudiometer. Residue renders lime-water milky. Of Gas Lighting. 1282. The gaseous compounds of carbon and hydrogen have been much applied to the purpose of illumination. 12d3. The gas, for this purpose, is obtained by the destructive distillation of bitu- minous coal, oil, or resinous substances, and is received in gasometers, whence it is distributed through pipes to the burners. (C17, 1252.) 240 INORGANIC CHEMISTRY. 1284. One of the greatest obstacles to the general employment of gas lights as a substitute for candles and lamps, is the necessity of pipes leading from gas- ometers to all situations where the light is wanted. The condensation of the gas into strong metallic re- ceivers, has been resorted to in order to obviate this difficulty. This process may be illustrated by means of the apparatus described for the impregnation of water with carbonic acid, being modified as represent- ed in the adjoining cut. 1285. It is only necessary to exchange the commu- nication with the self- regulating reservoir of carbonic acid gas, for a similar communication with a reservoir of olefiant gas; and the copper vessel being first ex- hausted of air, to condense the gas into it. The sy- phon used for the efflux of the impregnated water, is replaced by a cock and tube, the latter terminating in a capillary perforation. Through this, the gas may be allowed to escape in a proper quantity to produce a gas light when inflamed. It has, however, always appeared to me, that the expense of condensing the gas, and of procuring and transporting the receiver, would render this method of affording light disadvan- tageous. 1286. Latterly, the loss of gaseous matter, by con- densation, has been found so great as to render the process unprofitable. Of some Varieties of Carbohydrogen, and of the Bicarburet of Hydro- gen. 1287. Tetartocarbohydrogen, hexacarbohydrogen, and bicarburet of hy- drogen were all obtained by Mr. Faraday from the liquid which is deposited from oil gas, when condensed into vessels under great pressure for the pur- poses of illumination. 1288. On subjecting the matter, deposited as above described, to a very gentle heat, tetartocarbohydrogen is separated in the form of a transparent, colourless, inflammable gas, with a specific gravity of 1.9444. When cooled to zero, it condenses into a transparent colourless liquid of the specific gra- vity of 0.627, being the lightest liquid known. 1289. When the liquid remaining after the extrication of the tetartocar- bohydrogen is heated, vapour is evolved, and the boiling point continually rises until the temperature of 176 is attained. Between this temperature and 190, a large portion distils in the form of a liquid. When this liquid is cooled to zero, it separates into two compounds, one of which becomes solid, while the other continues liquid. The liquid is the compound which Dr. Thomson calls hexacarbohydrogen, though its composition does not ap- pear to have been well ascertained. It is inflammable, soluble in alcohol, and boils at 176. The solid compound is the bicarburet of hydrogen. It is at ordinary temperatures a colourless, transparent, volatile liquid, which boils at 186, and has a specific gravity of 0.85. At 32 it crystallizes, and, when cooled to zero, acquires a consistency like that of loaf sugar. Of Naphthaline. 1290. Naphthaline is obtained by subjecting to distillation the tar which is formed during the decomposition of bituminous coal. The first products are ammonia water, and the liquid called coal naphtha; but towards the close of the process, naphthaline is obtained. CA11BON. 241 1290- Naphthaline is a white crystalline substance, with an aromatic smell, and a pungent disagreeable taste. 1291. There are other compounds of carbon and hydrogen, native naphtha for instance, and oil of turpentine. The almost endless variety of the essential oils derived from vegetables, consist either wholly or principal- ly of carbon and hydrogen. Of some of these. I shall hereafter briefly treat ; to notice them all would be inconsistent with the limits prescribed to this work. Of the Compounds formed by Carbon with Chlorine and Hydrogen. 1292. It has already been stated that olefiant gas received its name in consequence of its being condensible with chlorine into a liquid of an oleaginous consistency. To this liquid the name of chloric ether has been improperly given, as it indicates a dependency on chloric acid for its con- stitution or generation, contrary to the fact. As it consists of two atoms of chlorine and one of etherine, a more appropriate name would be bichlorine ether. 1293. Bichlorine ether is limpid and colourless like water, has a pleasant smell, and an agreeable sweet .taste. 1294. Chlorine combines with several other of the polymeric varieties of carbohydrogen, forming with them compounds of different properties. It also produces two compounds by combining with the bicarburet of hydro- gen; one solid, the other liquid. COMPOUND OF CARBON WITH NITROGEN. Of Bicarburet of Nitrogen, or Cyanogen. 1295. Cyanogen ranks next to iodine among electro- negative bodies. It is included among the halogen bodies of Berzelius, and in the basacigen class by me. (625, 634.) Being a compound, I have deferred treating of it until now. 1296. Preparation. Cyanogen is obtained by subjecting pure and dry bicyanide of mercury to a low red-heat in a porcelain or coated glass retort or tube, and receiving the product over mercury. 1297. Properties. Cyanogen is a colourless, transpa- rent, irrespirable gas, which painfully affects the nose and eyes, and has a strong and peculiar odour. Under a pres- sure of four atmospheres, it becomes a colourless liquid, lighter than water. It may likewise be liquefied, or even solidified by cold. It is characterized by burning with a beautiful violet flame. It is decomposed by the electric spark, or by an incandescent iron into its constituents, car- bon and nitrogen. Alcohol dissolves twenty-three times, and water four and a half times its volume of cyanogen. In the course of a few days the solutions become discoloured, and a brown matter is deposited. The deposition from al- 31 242 INORGANIC CHEMISTRY/. cohol has been found to contain carbon and nitrogen. After obtaining cyanogen from the bicyanide of mercury, a black residuum is found in the retort, which has been conceived to consist of carbon with a lesser proportion of nitrogen than exists in cyanogen; but of late, this resi- duum, and the deposition from alcohol, have been supposed to be isomeric with cyanogen. 1298. When ignited with two volumes of oxygen, a vo- lume of cyanogen is converted into two volumes of carbo- nic acid and one of nitrogen, without condensation. Of course, as each volume of carbonic acid requires a volume of carbon vapour, there must exist two such volumes in one of cyanogen. Hence, as in the case of carbon and nitrogen each volume represents an atom, cyanogen con- sists of two atoms of carbon = 12 and one of nitrogen = 14 and its equivalent is 26 Of the Nomenclature of the Compounds of Cyanogen. 1299. When Prussian blue is digested with a solution of potash, and the resulting solution is filtered while hot, yellow crystals are deposited by re- frigeration, called ferroprussiate or ferrocyanate of potash, under the idea that they consist of an acid composed of iron, cyanogen, and hydrogen, in union with the oxide of potassium. Berzelius considers these yellow crys- tals as a double salt, formed by a " cyanure" of iron, and a " cyanure" of potassium. The name of this double salt, agreeably to his nomenclature, is " cyanure ferroso-potassique." There is another compound containing the same elements, in which the proportion of cyanogen to that in the first mentioned compound, is as 1$ to 1, and for which his name is "cyanure ferrico-potassique" 1300. The existence of these combinations constitutes one instance among many, in which, according to Berzelius, two compounds, each having the same halogen body as an ingredient, form by their union a double salt. 1301. 'Agreeably to his system, we have double " chlorures, bromures, fluorures" and " iodures" as well as double " cyanures" 1302. Some years ago, Bonsdorf, a skilful and sagacious German che- mist, assailed this classification of Berzelius, by showing that some of the " chlorures" of the double salts exercised an alkaline, others an acid reac- tion, with vegetable colouring matter; and that consequently the double " chlorures" so called by Berzelius, were really simple salts, in which one chlorure acted the part of an acid, the other of a base. Merely on con- templating the facts of the case, as stated by Berzelius, without having any knowledge of Bonsdorf's experiments and conclusions, the conviction arose in my mind that the double haloid salts, of that great chemist, should be considered as compounded of acids and bases. I cannot conceive where- fore Bonsdorf thought it necessary to show that the ingredients of a double chlorure should be capable of reacting with vegetable colouring matter, as if CARBON. 243 one of them were an acid, the other a base, in order to prove their preten- sions severally, to acidity and basidity.- (629.) It appears to me, that, excepting in the case of the alkalies and alkaline earths, those properties have not been deemed essential to oxacids and oxibases, and that of course they ought not to be required in acids or bases formed by any other of the basacigen class. Agreeably to the definition of acids and bases, on which the basacigen classification is founded, (625 to 632,) the " cyanure" of iron being electro-negative as .contrasted with the " cyanure" of potassium, the one must be deemed a cyanobase, the other a cyanacid. 1303. It has been mentioned that by the British and French chemists the termination in ide was made to indicate a compound formed by a supporter of combustion with a combustible or radical, while the termination in uret or ures was employed to designate a compound formed of two radicals. The difference in the practice of the two schools arose from the extension of the class of supporters by the chemists of Great Britain to the simple halogen elements of Berzelius, while, according to those of France, oxygen was the only supporter, all the other elements being combustibles or radi- cals. (685, &c.) Hence, according to the latter, only the compounds formed by oxygen have been distinguished by the termination in ide as in oxide; while, according to the former, in addition to those formed with oxygen, we have such as are formed by chlorine, bromine, iodine, and fluorine, distin- guished by the termination in ide, as has been already, to a certain extent, explained. (685.) 1304. By Berzelius the termination in ide is only resorted to where the radical is an electro-negative body; or, in other words, a body of which the oxides go to the positive pole. When the radical is one of those bo- dies which, when oxydized, go to the negative pole, the termination in ure is resorted to. I object to this complicated nomenclature, as founded on the error of not allowing those characteristics of acids and bases which have been acted upon by chemists in general, and by Berzelius himself in the case of oxacids and oxibases, to extend to the binary compounds formed by the bodies of the halogen class. 1305. I consider the yellow salt in question, as consisting of a cyanacid containing an atom of cyanogen and an atom of iron, and which I would call cyanoferrous acid, united to a cyanobase of potassium, consisting of one atom of cyanogen, and one atom of potassium, and forming a cyano- ferrite of potassium. The double salt, consisting of the same elements, but containing both in the acid and base, half an atom more of cyanogen, should, by analogy with the oxacids, have its acid distinguished by the name of cyanoferric acid, and should itself be called cyanoferrate of po- tassium. Of Cyanic, Cyanuric, and Fulminic Acids. 1306. An atom of cyanogen, combined with an atom of oxygen, forms cyanic acid, which may be obtained in union with potash, by igniting peroxide of manganese with ferroprussiate of potash, or cyanoferrite of potassium; being the salt alluded to above, as consisting of cyanogen, iron, and potassium. The cyanogen and potassium are converted, by the excess of oxygen in the manganese, into cyanic acid and potash, which unite, forming a cyanate of potash. Cyanic acid cannot, however, be obtained from the cyanates, in consequence of its extreme susceptibility of decom- position. 1307. A crystalline substance may be procured from human urine, which 244 INORGANIC CHEMISTRY. is known by the name of urea. It consists of carbon, nitrogen, oxygen, and hydrogen, in the proportion to form one atom of cyanic acid, one atom of ammonia, and one atom of water. When urea is subjected to heat, ammonia escapes, and an acid remains, which was supposed to consist of one atom of cyanogen, and two atoms of oxygen. But it has been recently ascertained by Wohler and Liebig, that it consists of the elements of cyanic acid, chemically united to the elements' of water; an atom of hydrogen, and an additional atom of oxygen, entering into its composition, not as water, but as essential constituents. Under these impressions, a new name, cyanuric, was given to it. This acid is solid, fixed, inodorous, and nearly tasteless. By combining with two atoms of water, as water of crystalliza- tion, it becomes capable of forming large crystals. 1308. When anhydrous cyanuric acid is exposed, in a glass retort, to a low red-heat, the extricated vapours being collected in a receiver refrigerated by a freezing mixture, hydrous cyanic acid is obtained. This acid and cyanuric acid consist of the same elements in the same proportion, but possess different properties and atomic weights. Hydrous cyanic acid is a colourless, volatile liquid, possessing a penetrating odour resembling that of acetic acid. It vesicates the skin when applied to it, exciting intense pain. Its vapour reddens litmus paper, is inflammable, and so pungent as to produce tears, and cause severe pain in the hands. Cyanuric acid is comparatively inert in these respects, but is far less susceptible of decom- position; as it is not decomposed by solution in boiling nitric or sulphuric- acid, while hydrous cyanic acid is decomposed by the addition of water, 1309. Hydrous cyanic acid, at the ordinary temperature of the air, spon- taneously undergoes an explosive decomposition, attended by an evolution of heat, and is converted into a solid mass of dazzling whiteness. This mass consists of a variety of cyanuric acid, which differs from that above described, in being insoluble in water or nitric acid, and in being decom- posed by sulphuric acid. It is, therefore, to be considered as presenting a case of isomerism. (1153). 1310. It is remarkable that, although cyanuric acid consists of the same elements in the same proportion as hydrous cyanic acid, it carries the hy- drogen and oxygen which exist in it in the proportion to form water, into every combination which it forms ; while the hydrous cyanic acid, in com- bining with bases, separates from the water, which must be considered, when in union with this acid, as acting as a base. 1311. To bodies which, although they contain the same elements in the same ratio, yet hold them differently associated, so that in reacting with other agents, they are resolved into, or form compounds differing in com- position, the term metameric has been applied. Thus hydrous cyanic, and cyanuric acid are said to be metameric with regard to each other. 1312. Another compound of cyanogen with oxygen exists in the fulmi- nating mercury of Howard, and the analogous fulminating silver of Desco- tils. Liebig ascertained these compounds to contain an acid common to both, which he called fulminic acid, but which, agreeably to the analysis made by him and Gay Lussac, was identified in composition with cyanic acid. Yet, as the latter would not produce fulminating compounds, and differed in its other properties, these acids have been considered as afford- ing another instance of isomerism. Mr. Edmund Davy, however, alleges- the existence of hydrogen in fulminic acid, and likewise that the nitrogen exists in excess, beyond the proportion appropriate to cyanogen. 1313. Fulminic acid is a colourless, transparent, volatile liquid, which CARBON. 245 reddens litmus, and produces a taste at first sweet, but afterwards astringent and disagreeable. Its fumes have a pungent and disagreeable odour, and produce headach when incautiously inhaled. 1814. Besides these acids, M. Liebig has recently discovered another, which is polymeric with regard to cyanUric acid; as it consists of the same elements in the same ratio, though twice as much of each enters into the composition of an atom. Of the Chlorides, Bromides, and Iodides of Cyanogen. 1315. Chlorine forms two compounds with cyanogen, a protochloride and a perchloride. The protochloride is a colourless, fetid gas, which may be liquefied, and even solidified by cold. In common with several other compounds of cyanogen, it possesses, even when gaseous, the singular pro- perty of producing pain by contact with the skin. The perchloride is a white crystalline substance, with an odour resembling that of mice. 1316. Bromine and iodine both form with cyanogen, crystalline com- pounds. The chlorides and bromides of cyanogen are energetic poisons. Of Sulphocyanogen. 1317. It has been stated that the yellow salt, usually known as ferro- prussiate of potash, is by Berzelius considered, when free from water, as consisting of cyanogen, iron, and potassium ; also that I consider it as a cyanoferrite of the cyanobase of potassium. When this salt, desiccated to efflorescence and finely pulverized, is mingled with flowers of sulphur, and exposed to a red-heat in a porcelain crucible, the iron is displaced; the sul- phur and cyanogen uniting, form a compound called sulphocyanogen, and this uniting with the potassium, constitutes a sulphocyanide. (1302.) 1318. Sulphocyanogen has been isolated by passing chlorine through a solution of sulphocyanide of potassium, or by subjecting that compound to nitric acid. Sulphocyanogen has some pretensions to be classed with the halogen, and of course with the basacigen bodies. 1319. The intense blood-red colour which it produces with iron, is the most striking property of sulphocyanogen, and has led to the impression that the sulphocyanide of iron may be the colouring matter of the blood. 1320. Sulphocyanogen is solid, insoluble in water or alcohol, and may, in its anhydrous state, be sublimed without change. It is composed of one atom of cyanogen, and two atoms of sulphur. 1321. Dr. Thomson states that another compound of sulphur and cyano- gen exists, containing one atom of sulphur and two atoms of cyanogen. This compound may be obtained in transparent colourless crystals. It is volatile, possesses a strong smell, and is soluble in water. When applied to the tongue, even in a minute quantity, it produces intense pain; and the part touched remains red and painful for some time. Of Sulphocyanhydric Acid. 1322. This acid may be obtained from a solution of the sulphocyanide of potassium, by the addition of phosphoric acid. Water is decomposed, the oxygen unites with the potassium, forming potash, with which the phos- phoric acid combines, and the hydrogen with the sulphocyanogen, formino; sulphocyanhydric acid, which may be separated by distillation. This acid is liquid and colourless, has an acid taste, and powerful odour. It becomes 246 INORGANIC CHEMISTRY. solid at 14, and boils at 216. It is composed of one atom of sulpho- cyanogen, and one atom of hydrogen. Of Cyanhydric or Prussic Acid. 1323. One atom of cyanogen, equivalent 26, with one atom of hydrogen, equivalent 1, forms one atom of cyan- hydric acid, equivalent 27. 1324. This acid has been detected in water distilled from bitter almonds and from laurel leaves, also, from peach leaves or blossoms. Between the odour of these, and that of the acid when dilute, it would be difficult to discriminate. 1325. Laurel water has long been known as a poison. Water distilled from peach leaves has been used to impart an agreeable flavour to food. Some peach leaf water, prepared by Mr. Wetherill, gave indications of cyanhydric acid, by producing a blue colour with a solution of iron. 1326. There have been instances in which noyeau, a cordial made from the kernels of bitter almonds, has proved poisonous from the presence of cyanhydric acid. 1327. There is a salt consisting of two atoms of cyano- gen and one of mercury, called bicyanide of mercury. When this salt is subjected to the action of chlorohydric acid, the chlorine forms a chloride with the mercury, while the hydrogen forms cyanhydric acid with the cyanogen. 1328. It may be more conveniently obtained by impreg- nating with sulphydric acid, a solution containing sixty grains of bicyanide of mercury for every ounce of water. The hydrogen unites with the cyanogen, while the sulphur precipitates with the metal. Any excess of the sulphydric acid is easily removed by the carbonate of lead. The apparatus for impregnation with sulphydric acid, has been described already. (797-8.) 1329. The acid may be procured in its most concen- trated form, by exposing the bicyanide in crystals, in a tube, to sulphydric acid gas, and employing a receiver, surrounded by salt and snow, to condense the vapour evolved. 1330. In performing this process, I found great difficulty to arise from the inability of the operator to regulate the quantity of gas introduced into the tube, so that, on the one hand, there might be no absorption of atmospheric air, and, on the other, no excess of the gas escaping, and CARBON. 247 consequently causing a loss of materials, and annoyance to the bystanders. This difficulty is in great measure re- moved, by means of the apparatus of which an engraving and description is subjoined. Apparatus for the Evolution of Cyanhtjdric or Prussic Acid. 1331. Let a tube, three-fourths of an inch in bore and about two feet in length, be bent at right angles, at about six inches distance from one end. Let the shorter portion be drawn out into a tapering form, with a bore not exceeding a tenth of an inch in diameter. Upon the larger orifice let a brass band be cemented, in which a female screw has been cut, so that a stuffing-box, furnished with a corresponding male screw, may be easily fastened air-tight to the band, or removed when desirable. Through the stuffing-box an iron rod passes, flattened like an oar at the end, which is within the tube when the stuffing-box is in its place. There must likewise be a lateral aperture in the band communicating with the cavity of the tube, and fur- nished with a gallows screw. The main body of the tube is to be situated nearly level, yet a little inclined towards the curvature, so that the tapering extremity may descend nearly perpendicularly into a tall narrow phial, surrounded by a freezing mixture. The horizontal portion of the tube near the bend should likewise be re- frigerated. The apparatus being thus arranged, introduce a sufficient quantity of the by cyanide of mercury into the tube, and close it by inserting the stuffing-box with its rod. In the next place, by means of the gallows screw, make a communi- cation between the cavity of the tube, and a self-regulating reservoir of sulphydric acid. This gas must be allowed to pass into the tube very slowly, and meanwhile, by means of the rod, the bicyanide is to be stirred. Before long a portion of the cy- anhydric acid will be seen in the narrow part of the tube. This serves to regulate the admission of the sulphydric acid, since, when the quantity passing into the tube is inadequate, the liquid will rise in the tube; when too great, it will be expelled from it. By these means, after a little while, all the bicyanide will be decomposed, and a corresponding quantity of acid collected in the refrigerated phial. 1332. Since this figure was engraved, I have found it preferable to have a phial made with a bottom tapering to a point, so that the quantity of acid, however minute, becomes apparent; and it is sooner rendered competent 'to act as an index of the pro- gress of the process; so as to regulate the quantity of gas to be allowed to enter the tube. It has also been found advantageous to mix the bicyanide intimately with about twice its bulk of glass, powdered to the consistency of coarse sand. New Process for Liquid Cyarihydric Acid. 1333. The following process for procuring prussic acid, is recommended by Professor Everitt.* 1334. For every 212 grains of ferroprussiate of potash (cyanoferrite of potassium,) in 2 ounces of water introduced into a retort, add as much sul- * London and Edinburg Philosophical Magazine, vol. 6, p. 100. 248 INORGANIC CHEMISTRY. phuric acid as may be equivalent to 120 grains of the anhydrous acid; and distilling the mixture, let the vapour pass into a pint of refrigerated water, holding 255 grains of nitrate of silver. The resulting precipitate being washed and dried, should constitute nearly 201 grains of mercurial cyanide. Of this let 40 grains be introduced into 7 fluid ounces, and 20 minims of water; and add 40 minims of chlorohydric acid, of specific gravity of 1.129. The whole being well secured in a stoppered bottle, and agitated repeatedly, should be allowed to rest until the resulting chloride of silver subsides. In the solution thus obtained, when carefully decanted, there will be- one grain of prussic acid (more properly called' cyanhydric acid,) for every fluid ounce of water. 1335. Should there be a little excess of chlorohydric acid, agreeably to Professor Everitt's observation, confirmed by those of others, it will tend rather to preserve, than to decompose the acid. 1336. Properties of Cyanhydric Acid. This acid is a colourless liquid, which emits a powerful odour, resembling that of peach blossoms. When perfectly free from water, it is far more volatile than ether, as it boils at 79 F., and evaporates so rapidly, that one portion becomes frozen by the loss of the caloric which the other absorbs in passing into the aeriform state. Its specific gravity is 0.7058, be- ing nearly the same as that of sulphuric ether. 1337. Anhydrous cyanhydric acid is sometimes decom- posed in a few hours, especially if not protected from the light, and can never be preserved longer than a fortnight. Either when in the state of a liquid, or vapour, this acid is probably the most active poison known. The applica- tion of a few drops to the arm of a man has produced death, and its fumes are equally deleterious when inspired. As when free from water, this acid boils at 79, nearly 20 below the temperature of the blood, it must be converted into vapour too soon to produce its full effect. From a cavity like the ear, the pure acid must be ejected in vapour immediately. I am, therefore, under the impression that it is less effectual as a poison when anhydrous, than when combined with a minute proportion of water. 1338. Upon one occasion, touching the ear of a rat con- fined in a glass jar with a drop of the anhydrous acid, the animal, being obliged to breathe the vapour, died instanta- neously with a slight sneezing. Yet upon another occa- sion nearly half a drachm was injected into the ear of a large dog, without causing death; a like quantity, subse- quently injected into his nose, proved fatal. The acid em- ployed was so pure as to freeze by its own evaporation. HURON. 249 1339. The best antidotes for this poison are chlorine or ammonia, in dilute aqueous solution, especially chlorine. 1340. Cyanhydric acid is sometimes employed in medi- cine, though in very small doses, and in a very diluted state. 1341. It has been proposed to detect cyanhydric acid, in cases in which it may have been employed in poisoning, by subjecting the stomach and its contents to distillation with water, and testing the liquid product by copper or iron. 1342. I should place much reliance on the characteristic smell of the acid, which is that of peach blossoms, and which may be perceived, not only from the presence of the acid, but likewise from that of any of the cyanides, if subjected to the action of chlorohydric acid. Experimental Illustrations. 1343. The processes for the production both of the aqueous and anhydrous cyanhydric acid, exhibited; also, the congelation of the latter by the cold arising from its own evaporation. SECTION V. OF BORON. 1344. Preparation. By the addition of sulphuric acid to a saturated solution of biborate of soda (borax) in wa- ter, shining crystalline plates are precipitated, consisting of boric acid. From these crystals boron may be obtained, either by the action of a powerful Voltaic series, or by first vitrifying them, then finely pulverizing the resulting glass, and afterwards heating the acid thus prepared in contact with potassium. 1345. Boron may be obtained by means of the appa- ratus employed for the evolution of silicon, (1355, &c. 1357, &c.) substituting fluoboric acid gas for fluosilicic acid gas. 1346. Properties. Boron is of a dark olive colour, taste- less, inodorous, a non-conductor of electricity, and insolu- ble either in alcohol, ether, or the oils. Its atomic weight 32 250 INORGANIC CHEMISTRY. is 11. It is susceptible neither effusion nor volatilization. When heated in the air to 600 F, it takes fire, and, by uniting with oxygen, generates boric acid. Nevertheless only a portion of the boron is oxydized, the remainder being protected by a crust of fused boric acid. If this crust be removed by water, the boron will be found to have undergone a change similar to that produced in char- coal by an intensely high temperature. It is rendered harder, more difficult to ignite, and so much denser, that, although its specific gravity was before only 1.83, it now sinks rapidly in sulphuric acid of the specific gravity of 1.844. Before it has been ignited, boron is slightly solu- ble in water; and its solution, when evaporated to a cer- tain point, forms a gelatinous mass, which, by complete desiccation, becomes opaque, and assumes the usual ap- pearance of boron. COMPOUND OF BORON WITH OXYGEN. Of Boric* or Boracic Acid. 1347. The means of procuring this acid have been men- tioned in describing the process for obtaining boron. Bo- rax is a biborate of soda, from which boric acid may be liberated in crystals, as above described, by the superior affinity of sulphuric acid for the soda. 1348. Properties. Boric acid is crystalline as first ob- tained from borax, but forms a glass when deprived by heat of its water of crystallization. It is colourless, in- odorous, almost tasteless, and sparingly soluble in water. In the form of an aqueous solution, its agency is weak, and it is in consequence rarely used in that state. In com- mon with silicic, phosphoric, and arsenic acid, being fixed at temperatures at which sulphuric and nitric acid are de- composed, it will at those heats expel them from their combinations; although, when water is present, and at low temperatures, , it is displaced from combination not only by those acids, but by many others. It consists of one atom of boron, and three of oxygen. 1349. Boron, in its habitudes, seems to lie between phosphorus and carbon. In its insusceptibility of volatili- * I agree with the French chemists and Berzelius, in employing the word boric instead of Loracic, as more naturally generated from boron, by analogy with the other acids formed with radicals, to the last letter of which the letters ic are usually added. Apparatus for the Evolution of Silicon. A (Page 251.) SILICON. 251 zation, infusibility, and the temperature requisite for its combustion, it is most allied to carbon; yet boric acid is more analogous to phosphoric than to carbonic acid. Both phosphoric and boric acid are capable of being re- duced to a vitreous state, and bear a white-heat without being volatilized; while the acid of carbon is naturally aeriform. 1350. Boric acid and the biborate of soda are of great use in blowpipe assays, as fluxes, and in soldering, as the means of protecting metallic surfaces from oxidation. Experimental Illustrations. 1351. Saturated solution of borax, decomposed by sul- phuric acid. Exhibition of crystals of the acid and of the biborate, which are severally fused into a glass by the compound blowpipe. Effects of cobalt and manganese upon the colour of the glass, of which a globule is conve- niently supported by a platinum wire. Of Chloride of Boron. 1352. The chloride of boron maybe obtained by the combustion of boron in chlorine ; or by passing a current of chlorine over a mixture of charcoal and boric acid, heated to redness in a porcelain tube. 1353. The chloride of boron is a colourless gas, possessing a strong and peculiar smell. When brought in contact with water, a reciprocal decom- position takes place, and boric and chlorohydric acid result. It forms a white salt with ammonia, and is by some chemists considered as an acid. VI. OF SILICON. 1354. Preparation. By heating sulphuric acid with a mixture of powdered Derbyshire spar, and powdered glass* or quartz, a permanent gas may be obtained. When po- tassium is heated in this gas, silicon is evolved. Apparatus for evolving Silicon from Fluosilidc Add, Gas by means of Potassium. 1355. This apparatus is represented by the opposite engraving. Into a stout ma- hogany block as a basis, two iron rods, A A, are so planted as to extend perpendicu- larly, and of course parallel to each other, about two feet in height. Upon these rods two iron bars are supported horizontally, one B, near their upper extremities, the other, at the height of about six inches from the wooden basis. In the centre of the lower bar, there is a screw, D, having a handle below the bar, and supporting above it a circular wooden block. Into a hole in the upper iron bar, equidistant from the rods, is inserted a hollow brass cylinder, C, which at the lower end screws into 252 INORGANIC CHEMISTRY. an aperture in a circular plate of brass, E, which is thus supported horizontally a few inches below the bar. By these means, room is allowed for the insertion into the cylinder of four valve cocks, each furnished with a gallows screw. The cylinder is surmounted by a stuffing-box, F, through which a copper sliding-rod, G, passes air-tight. The brass plate is turned and ground to fit a bell glass of about five inches in diameter, and eight inches in height, which is pressed up when necessary between the plate and the block, by the screw, D, supporting the block. Within the space comprised by the bell glass, and on one side of the centre of the plate, two stout brass wires are inserted, one of them insulated by a collar of leathers, so as to admit of the ignition, by a galvanic discharge, of a small arch of platinum wire, which reaches from one to the other. The sliding-rod abovementioned as occupying the stuffing-box, terminates below the plate in an elbow which supports a cup at right angles to the rod, at the same distance from the rod as the platinum wire; and on the opposite side of it, there is a brass cover, H, for the cup, supported from the plate. The arrangement is such, that by a suitable movement in the sliding-rod, made by grasping it by the handle, G, in which it terminates externally, the cup may be made either to receive into its cavity the platinum wire, or to adjust itself to its cover, H. 1356. The bell being removed, about sixty grains of potassium, in pieces not con- taining more than fifteen grains each, are to be introduced into the cup, which is then to be adjusted to the cover, and the beli secured. In the next place, by means of the flexible lead tubes, P, P, P, P, and the gallows screws attached to the valve cocks, established a communication severally with an air pump, a self- regulating reservoir of hydrogen, a barometer gauge, and ajar over the mercurial cistern, con- taining fluosilicic acid gas. First, by means of the air pump, exhaust the bell, and, in order to wash out all remains of atmospheric air, admit hydrogen from the reser- voir. Again exhaust, and again admit hydrogen. Lastly, exhaust the bell of hydro- gen, and admit the fluosilicic acid gas. By means of the gauge, the exhaustion is indicated and measured, and by the same means it will be seen when the pressure of the gas within the bell approaches that of the atmosphere. When this takes place, the cocks being all closed, and by means of the process of galvano-ignition, (335, &c.) the platinum wire being rendered incandescent, the potassium is to be brought into contact with it. A peculiar deep red combustion ensues, evolving copiously chocolate-coloured fumes, which condensing into flocks of the same hue, descend throughout the receiver, and are deposited upon the interior surface, so as to create in the mind of the spectator, the idea of a miniature fall of chocolate-coloured snow. On removing the bell after the potassium has ceased to burn, the cup which held it is found to contain silicon mixed with the fluoride of potassium, and with this the whole of the chocolate-coloured deposition is contaminated. Siliciuret of potassium is likewise found in the cup ; since, upon the affusion of water, a fetid inflammable gas is evolved, which has an odour resembling that of phosphoretted hydrogen, and which must obviously be the analogous compound siliciuretted hydrogen. The sili- con, being insoluble, may be separated from the fluoride by digestion in water. When the potassium employed is of the kind obtained by means of charcoal, the silicon is, as Berzelius alleges, adulterated with carbon. I am under the impression that strong nitric acid removes this impurity. Simple Process for the Evolution of Silicon. 1357. Last winter I was enabled to adopt a much more simple and con- venient process for the evolution of silicon, which is as follows: 1358. A bell glass was filled, over mercury, with fluosilicic acid. By means of a bent wire a cylindrical cage of wire-gauze, containing a few globules of potassium, was introduced through the mercury into the cavity of the bell, and supported in a central position. A knob of iron was welded to the end of a rod, of the same metal, so recurved as to reach the cage with ease. Having been heated nearly white-hot, this knob was passed through the mercury, so as to touch the cage. By these means the potas- sium having been made to enter into combustion with the fluorine, the sili- con was evolved. Much of this substance remained attached to the cage in combination with fluoride of potassium. From the impurities, with which it was thus associated, the silicon was separated by washing in water and digestion with nitric acid. There can be no doubt that this process may SILICON. 253 be employed to evolve boron, by employing fluoboric acid instead of fluo- silicic acid. 1359. Properties of Silicon. It is of a brown- ash co- lour, without the least trace of metallic lustre, a non- conductor of electricity, infusible, and incapable of being volatilized. It is not liable to be dissolved or oxydized by sulphuric, nitric, chlorohydric, or fluohydric acid, but is soluble in a mixture of nitric and fluohydric acid. When heated to redness with the fixed alkaline carbonates, it burns vividly; and when dropped upon the hydrates of potash, soda, or baryta, while in a state of fusion, it ex- plodes. Yet it is unchanged by ignition with chlorate of potash, and exercises but a feeble reaction with nitre, even when heated to redness. In these respects its habitudes are anomalous. 1360. When silicon, as usually obtained by the aid of potassium, is intensely heated in the air or in oxygen gas, it burns with a feeble blue flame; but, by becoming en- crusted with silicic acid, a portion escapes combustion. This portion is rendered harder, denser, and insusceptible of combustion with oxygen at the highest temperatures. Berzelius suspects the greater combustibility, and inferior density and hardness of silicon, in the state in which it is obtained by the process above described, to be due to the presence of hydrogen, derived from the water employed. In this state, it inflames when ignited in the vapour of sulphur, and forms a sulphide, which is decomposed by water into sulphydric and silicic acid. COMPOUND OF SILICON WITH OXYGEN. Of Silica, or Silicic Acid. 1361. One atom of silicon with one atom of oxygen, each equivalent to 8, forms one atom of silicic acid, equi- valent 16. 1362. Preparation. Quartz being powdered, and fused with three times its weight of pearlash, a glass is obtained, which, being soluble, forms with water a liquid, called for- merly liquor silicum, or liquor of flints. An acid being poured into this solution, silicic acid, slightly contami- nated by potash, is precipitated. 1363. To obtain silicic acid, Berzelius advises us to fuse in a platinum crucible, equal parts of the carbonates of 254 INORGANIC CHEMISTRY. potash and soda, and to add quartz, finely pulverized, in small successive portions. The effervescence arising from the addition of one portion, is allowed to subside before adding another, until effervescence can no longer be excited. The refrigerated mass is dissolved in chlorohydric acid, and the solution filtered and evaporated to dryness. To remove all traces of iron or alumina, the dry mass is kept moist with chlorohydric acid, during about two hours, and afterwards washed with hot water, and then exposed to a red-heat. Silicic acid will remain in a sufficient de- gree of purity. 1364. Pure silicic acid, in the well known form of rock crystal, is found throughout nature. Its usual crystalline form is a six-sided prism, terminated by a pyramid with six faces. 1365. Properties. Pure silicic acid is white, tasteless, and inodorous, and has a specific gravity of 2.66.' Its solution does not redden litmus, and, when evaporated to a certain point, forms a translucent jelly. It is soluble when nascent, but insoluble after exposure to heat or de- siccation, or in its native crystalline form. 1366. It was first fused by myself, in the year 1801, by means of the compound blowpipe. It has never been volatilized. Of Chloride of Silicon. 1367. When silicon is heated in chlorine it inflames, evolving heat and light, and a chloride of silicon is formed, which is a volatile liquid, possess- ing a sharp and powerful odour. In consequence of the absorption of an excess of cjilorine, it is generally coloured yellow. It boils below 212, and, by the addition of water, is converted into chlorohydric and silicic acid. Experimental Illustrations. 1368. Silicate of potash, exhibited ; also the solution of it, called liquor silicum, from which silica is precipitated by means of an acid. Of Glass. 1369. If the proportions, in which sand and alkali are used as above- mentioned for the liquor silicum, be reversed, the insoluble compound of silicic acid and alkali, known under the name of glass, is obtained, which, however pure the materials, has a slight tinge of green. This is removed by a due admixture of the red oxide of lead, and black oxide of manganese. 1370. Annealing Process. A sudden diminution of the quantity of SILICON. 255 caloric among the exterior particles of a thick piece of glass in a state of ignition, is not attended by a corresponding diminution of the quantity of this principle among the particles within, owing to the slowness with which glass conducts heat. Hence, there can neither be a general coherence, nor a uniform arrangement among the particles ; unless the cooling be very slow, so as to allow the refrigeration, within and without, to be nearly si- multaneous. As it never can be perfectly simultaneous, the annealing will always be defective, other things being equal, in proportion as the glass is thicker. Were the particles subjected to radiant heat only, the process would be more effectual ; as this, when proceeding from incandescent sur- faces, has been ascertained to penetrate and even to pass through glass. 1371. By gradually making up a fire of charcoal, at about four 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 it red-hot, without causing a fracture. From its situation, it was subjected to radiant heat only. 1372. By opening a perpendicular hole in an anthracite fire, I have been enabled, with little delay, to introduce the beaks of glass retorts of two or three gallon in capacity, without causing a fracture. Thus situated, the glass soon becomes almost fluid, so that by its own weight the lower por- tion is drawn downwards into a tapering tube, and would be made to fall off were the beak not removed from the fire. If removed in due time, the body of the retort may be so held as to cause the tapering portion of the beak to form such an angle with the other part, as to be capable of enter- ing the tubulure of another retort, as described in one of the processes for procuring pure chlorohydric acid. (891.) 1373. By like means, the beaks of broken retorts, or any piece of a glass tube, may be made to taper, to be elongated so as to be inserted through the tubulure of a retort, and to serve, consequently, when luted to the tubu- lure, for the introduction of sulphuric acid, in various processes besides that to which allusion is above made. 1374. Prince Rupert's Drops. When glass, in a state of fusion, is dropped into water, the defective states of cohesion and arrangement, con- sequent to the want of annealing, are at the maximum. Such drops have, long been known under the name of Prince Rupert's drops. It is only necessary to break off the slender filament in which the mass terminates, in order to cause an explosive dispersion of the whole into a coarse powder. 1375. The cohesion of the particles in glass tubes, is often nearly as im- perfect as in Prince Rupert's drops. The slightest mark from a file on the interior surface, or even wiping them out, especially if a metallic wire be employed, may cause them to break into pieces. Sometimes the fracture ensues immediately, at other times, not till many hours have intervened. COMPOUNDS OF FLUORINE WITH HYDROGEN, BORON, AND SILICON. 1376. Fluorine has been briefly noticed, (746, &c.) I deferred treating of the interesting compounds formed by this element with hydrogen, boron, and silicon, until the student should be acquainted with those substances. 1377. The three fluorides referred to are called seve- rally jluoJiydric, Jluoboric, and Jluosilicic acid. (862). 256 INORGANIC CHEMISTRY. Of Fluohydric Acid, generally called Hydrofluoric Acid. (856.) 1378. Fluorine exists in nature in union with the metals of the earths and alkalies, especially with calcium, a metal of which lime is the oxide. Such compounds are called fluorides. The remarkable mineral, called Derbyshire or fluor spar, is a fluoride of calcium. 1379. Not long since, Derbyshire spar was considered a compound of lime with an acid, called fluoric acid, and supposed to consist of oxygen and an unknown radical. Mr. Ampere first suggested the present doctrine, which was soon adopted by Sir H. Davy, and is now, I believe, universally sanctioned. 1380. Preparation. When fluoride of calcium is pulverized, and heated in a leaden retort with twice its weight of concentrated sulphuric acid, the water in combination with the acid is decomposed. The oxygen and acid form sulphate of lime with the calcium; while the hydrogen produces with the fluorine, fluohydric acid, which passes over in the form of a very vola- tile acid vapour, and may be condensed in a leaden or silver receiver, sur- rounded by a mixture of snow and salt. If received in water, it condenses without refrigeration, and forms a diluted acid. 1381. Properties. Fluohydric acid is a colourless, limpid liquid, which boils at a little below 60. When anhydrous, its specific gravity is 1.0609. It is so volatile, that, in a close apartment it cannot be decanted without subjecting the operator to intolerable fumes. This operation must be per- formed where there is a current of air to carry them off. 1382. It ulcerates the skin with peculiar activity, and corrodes glass so as to trace its course indelibly, in running over the surface. It must be kept in vessels of silver or lead, accurately closed. When received in water it is absorbed, forming aqueous fluohydric acid, and is then more easily preserved. 1383. One atom of hydrogen, equivalent 1, with one atom of fluorine, equivalent 18, is supposed to form one atom of fluohydric acid, equiva- lent 19. Experimental Illustrations. 1384. Powdered fluoride of calcium, heated with sul- phuric acid in a leaden retort, adapted to a receiver sur- rounded by a mixture of snow and salt. Same process, substituting a receiver with water, by means of Knight's apparatus. Effect of fluohydric acid upon glass. Of Fluoboric Acid. 1 385. Preparation. It may be obtained by intensely heating a mixture of two parts of powdered fluoride of calcium, with one of vitrified boric acid, in an iron tube. One part of the boric acid is decomposed, the oxy- gen of which, and the remaining portion of the acid, form borate of lime with the calcium; while the boron unites with the fluorine, forming fluo- boric acid gas, which must be received over mercury. Fluoboric acid gas, may likewise be procured, by heating in a glass retort two parts of fluoride of calcium and one of boric acid, with twelve parts of concentrated sulphu- ric acid. Berzelius, however, states that, when, obtained by this method, it is contaminated by fluosilic acid, arising from the action of the fluorine on SILICON. 257 the glass. This might, however, be avoided by performing the operation in a leaden retort. 1387. Dr. Thomson states that the best method of obtaining fluoboric acid gas, is one which was suggested by Berzelius. Boric acid is to be dissolved in anhydrous fluohydric acid, and a gentle heat applied to the solution. A reciprocal decomposition takes place; the hydrogen of the fluohydric acid combines with the oxygen of the boric acid, forming water, while the fluorine unites with the boron, and constitutes fluoboric acid gas. 1388. Properties. Fluoboric acid is a colourless, transparent gas, with a potent odour, and an acid taste. It reddens litmus paper, and is destruc- tive to life. Its specific gravity is 2.3622. Water absorbs seven hundred times its volume of this gas. When fluoboric acid is passed into water, the oxygen of a portion of the water unites with the boron, forming boric acid, while the hydrogen combines with the fluorine, producing fluohydric acid. The boric acid precipitates, and the fluohydric acid combines with the undecomposed portion of the fluoboric acid, forming a compound which Berzelius designates as hydrofluoboric acid, but which, according to the nomenclature which I have adopted, should be called fluohydroboric acid. If we continue to pass fluoboric acid gas into the water, or partially abstract this liquid by evaporation, until the solution of fluoboric acid becomes satu- rated, the affinities which were at first brought into play are reversed. The hydrogen of the fluohydric acid unites with the oxygen of the precipitated boric acid, and the fluorine with the boron; so that we finally obtain a simple solution of fluoboric acid in water. This solution is at first fuming; but on the application of heat it yields up a fifth part of its gas, and then strongly resembles concentrated sulphuric acid in appearance. Like that acid, it carbonizes organic products, in consequence of its affinity for water. 1389. Three atoms of fluorine, equivalent 54, and one atom of boron, equivalent 11, form one atom of fluoboric acid, equivalent 65. (856, &c.) . Of Fluosilicic Acid. 1390. Preparation. It may be obtained by adding to the materials for evolving fluohydric acid, one half their weight of finely powdered glass, subjecting the mixture to heat in a glass retort, and receiving the product over mercury ; as by water it would be rapidly absorbed. 1391. The oxygen of the silicic acid in the glass, with the sulphuric acid and calcium, forms a sulphate of lime ; while the fluorine and silicon escape in the form of fluosilicic acid gas. 1392. The apparatus which I employ for fluosilicic acid, is precisely the same as that described under the head of ammonia. 1393. Properties. Fluosilicic acid is a transparent, colourless gas, with a peculiar and suffocating odour, closely resembling that of chlorohydric acid. It reddens litmus paper, and has a specific gravity of 3.5735. When brought in contact with water it is rapidly absorbed, and a decomposition takes place, similar to that which ensues in the case of fluoboric acid under similar circumstances. Silicic acid is deposited in the form of a gelatinous mass, and fluohydric acid is produced, which combines with the undecom- posed portion of the fluosilicic acid, forming a compound called hydrofluo- silicic acid, to which, if it be an acid, I would give the name of f.uohydro- silicic acid. If the water in combination with the fluohydrosilicic acid be partially removed by heat, fluosilicic acid gas escapes, leaving fluohydric acid in solution. 33 258 INORGANIC CHEMISTRY. 1394. One atom of fluorine, equivalent 18, with one atom of silicon, equivalent 8, forms one atom of fluosilicic acid, equivalent 26. Experimental Illustrations. 1395. Production of fluosilicic acid, shown: also its ab- sorption by water, and the precipitation of silicic acid, as above described. Of the Reaction of Fluohydric Acid with Fluoboric and Fluosilicic Acid, and of the Nomenclature of the Compounds formed by the latter on meeting with Oxibases. 1396. The union which ensues between fluohydric acid, and either fluo- boric, or fluosilicic acid, agreeably to the preceding statement, may appear anomalous, in the way in which it has hitherto been treated. If, however, I am correct in my mode of defining the difference between an acid and a, base, (631,) the combinations in question will not prove to be anomalous. I deem it consistent to suppose that a fluobase of hydrogen unites, in the one case, with fluoboric acid, in the other with fluosilicic acid; so that fluo- hydroboric acid might be called fluoborate of the fluobase of hydrogen, or more briefly, fluoborate of hydrogen; and in like manner, fluohydrosilicic acid would be called fluosilicate of the fluobase of hydrogen, or briefly, fluosilicate of hydrogen. 1397. When either fluohydroboric acid, or fluohydrosilicic acid, or in other words the fluoborate or fluosilicate of the fluobase of hydrogen, is brought into contact with an oxibase, the radical of the latter takes the place of the hydrogen, which, with its oxygen, forms water. Thus, in the case of potash, there would result a fluobase of potassium, usurping the place of the fluobase of hydrogen ; and of course either a fluosilicate, or fluoborate of potassium must be formed. Agreeably to the Berzelian nomenclature, these compounds are double salts, the name of one being in the French translation, "fluorure borico-potassique" that of the other, "fluorure silico-potassique." Many analogous salts, formed by the acids under consideration, with salifiable substances, are mentioned by Berzelius ; also many others, in which other radicals, in union with fluorine, play a part analogous to that performed by silicon and boron, in the salts above men- tioned. 1398. There are instances in which compounds, usually called bases, act as acids. Of course it is consistent that compounds, usually called acids, should in some instances act as bases. In this respect, a striking analogy may be observed between the union of the oxide of hydrogen (water) with the oxacids and oxybases ; and that of fluoride of hydrogen with fluacids and fluobases. According to Berzelius, water acts as a base to oxacids; as an acid to oxibases. So I conceive the fluoride of hydrogen acts as a base in the cases above noticed, while it acts as an acid in the compound of hy- drogen, fluorine, and potassium, called by Berzelius "Jluorure potassique acide." This compound I would call a fluohydrate of the fluobase of po- tassium, or more briefly, fluohydrate of potassium ; as we say sulphate of copper, instead of the sulphate of the oxide (or oxybase) of copper. ZIRCONION. 259 SECTION VII. OF ZIRCONION, OR ZIRCONIUM. 1399. There is a stone, known under the name of the jargon or zircon of Ceylon, from which Klaproth extricated an earth, to which the name of zirconia was given. This earth is an oxide of an elementary body, which has been called zirconion, or zirconium. The termination in um being now only applied by chemists to the names of substances having the metallic character, I think that it has been erroneously associated with the name of the element in question, since its pretensions to that character are not higher than those of carbon. OF METALLIC RADICALS. 1400. It is to metallic radicals that I deem it expedient in the next place to direct attention. Less than thirty years ago, the line of demarcation between metals and other bodies was easily drawn. There was then no known metal which had a specific gravity less than six; and of other bodies, none of which the specific gravity was as high as five. But the discovery of alkalifiable metallic radicals, having a specific gravity less than that of water, annihilated the barrier which had been established on the basis of superior gravity. 1401. Peculiar brilliancy and opacity were in the next place appealed to as the means of discrimination; and like- wise that superiority in the power of conducting heat and electricity, which was so remarkable in substances of a decidedly metallic character. Yet so difficult has it been to draw the line between metallic and non-metallic radi- cals, that bodies which are by some authors placed in one class, are by others included in the other. Thus seleni- um, silicon, and zirconion have by some chemists been comprised among the metals, by others among non-metallic bodies. In fact nature has not qualified her bodies for distinct classification. It is true that there are those of which the prominent features or qualities are so strikingly different, that we are at first encouraged to think that by associating similar substances with each, we shall form classes not liable to be confounded. Thus gold possesses, in a high degree, all the attributes of a metal, while sulphur is totally devoid of them; yet arsenic, as being decidedly metallic, may on the one side be classified with gold in 260 INORGANIC CHEMISTRY. preference to sulphur; while on the other hand, between arsenic and sulphur, there is in many respects a much greater analogy than between arsenic and gold. In fact, tellurium, which had been always classified and is still considered as a metal, is now associated by Berzelius, in his amphigen class, with oxygen, selenium, and sulphur, and has, in consequence, been treated of by me as a basa- cigen body. 1402. Metals were formerly distinguished as metals, and semi-metals; the latter appellation having been employed to designate such as were wanting in the mechanical pro- perties of malleability and ductility. Again, the metals which were endowed with the properties just mentioned, were divided into noble and base. The noble metals, sometimes called precious, from their superior value, were distinguished from the others by their insusceptibility of injury from fire, moisture, or air. Silver and gold were, about a century ago, the only known metals meriting the name of noble, upon the grounds which I have mentioned. To these platinum was subsequently added, and latterly palladium, nickel, iridium, and rhodium, have been found to have analogous pretensions, agreeably to the ideas in obe- dience to which the epithet was originally employed. Subsequently chemical properties became better known, and metals were associated not only in accordance with their own obvious characteristics, but also with a view to their oxides, which in many cases are the only forms under which they are met with in nature, or employed in the arts. Accordingly the metals are now generally divided with a view to their susceptibility of oxidizement, or the character of their oxides. Among the oxides alluded to, there are some of which the characteristics are so differ- ent, that there can be no hesitation in classifying them separately. Yet in other members of the same class, the characteristics by which they are distinguished are so feeble, that a diversity of opinion has existed as to the genera to which they belong. 1403. I propose to divide metallic radicals into the four following classes: First, metals of the earths proper. Second, metals of the alkaline earths. Third, metals of the alkalies, or alkalifable metals. Fourth, metals proper. ZIRCONION. 261 1404. I shall employ the words noble to distinguish metals not liable to be tarnished by exposure to fire, water, or air; as, for instance, gold, platinum, indium, palladium, rhodium, silver, and nickel. 1405. Metals proper are by Berzelius divided into elec- tro-negative or acidifiable metals, and electro-positive or basifiable metals. Under the former head he places sele- nium, arsenic, molybdenum, tungsten, antimony, tellurium, columbium or tantalum, and titanium. Under the head of electro-positive or basifiable metals, he places gold, plati- num, osmium, iridium, palladium, silver, mercury, copper, bismuth, tin, lead, cadmium, zinc, nickel, cobalt, iron, man- ganese, and uranium. 1406. I am under the impression that each of the fol- lowing metals, being, agreeably to the same authority, capable of forming with a halogen body the electro- negative ingredient in a double salt, should be considered as acidifiable; namely, gold, platinum, silver, palladium, iridium, rhodium, uranium, chromium, titanium, molybde- num, manganese, osmium, mercury, nickel, copper, iron, and zinc. 1407. When the objects which it may be desirable to study, are too numerous and complicated in proportion to the time and attention which we have to bestow; we may employ such time as we have, either in a cursory, super- ficial, and indiscriminate examination of the whole, or in a more thorough study of the more important parts. Of the two courses I cannot conceive that any judicious per- son would hesitate in choosing the latter. 1408. Under this impression I shall treat particularly of the twelve metals proper, included in the following list gold, platinum, silver, mercury, copper, lead, tin, iron, zinc, antimony, bismuth, and arsenic. Besides the metals thus mentioned, there are in the same class, palladium, rhodium, iridium, osmium, nickel, cadmium, chromium, cobalt, co- lumbium, manganese, molybdenum, titanium, tungsten, uranium, and vanadium. Of these 1 shall give only a brief account, with descriptions and illustrations of their striking and useful properties, where such exist. 1409. I subjoin a list of metallic radicals, comprising all the metals excepting tellurium; which has been treated of as a basacigen element. So far as our knowledge extends, the dates at which these metals severally became known, and the names of their discoverers, are mentioned. 262 INORGANIC CHEMISTRY. Table of Metals classified as Metallic Radicals, also of the dates at which they were discovered. Names of Metals. Authors of the discovery. Dates of the Discovery. Gold . . 1 Silver Iron Copper . }> Known to the Ancients. Mercury Lead . Tin . J Antimony . Bismuth Zinc . Described by Basil Valentine Described by Agricola First mentioned by Paracelsus 1490 1530 IGth century. Arsenic . ) Cobalt . 5 Brandt 1733 Platinum Wood, assay-master, Jamaica 1741 Nickel Cronstadt 1751 Manganese Tungsten Molybdenum Gahn and Scheele .... D'Elhuyart ...... Hielm 1774 1781 1782 Uranium Klaproth 1789 Titanium Gregor .... 1791 Chromium . Vauquelin 1797 Columbium Hatchett 1802 Palladium . ) Wollaston . . . . 1803 Rhodium . 5 Iridium Descotils and Smithson Tennant 1803 Osmium Smithson Tennant .... 1803 Cerium Hisinger and Berzelius 1804 Potassium . "| Sodium Barium . ^ Davy 1807 Strontium . Calcium . J i Cadmium Stromeyer ... . 1818 Lithium Arfwedson 1818 Aluminium ) Glucinium . > Wohler 1828 Yttrium . ) Thorium . 1829 Magnesium Vanadium . Bussy Sefstrb'm J829 1830 Of the Generic Characteristics of the Metals. 1410. When newly cut, metals have a peculiar lustre. They are the best conductors of heat and electricity ; the worst radiators and best reflec- tors of heat. All combine, directly or indirectly, with all the basacigen bodies in one or more proportions. (633.) They are all susceptible of solidity and fluidity, and probably of the aeriform state. Mercury and arsenic are easily volatilized ; and gold, silver, and platinum, though very difficult to burn or volatilize, are nevertheless dissipated by means of the compound blowpipe, galvanism, or electricity. Of Properties possessed by some Metals, but not by others. 1411. The properties which come under this head, are permanency of lustre in the fire and air ; malleability ; ductility ; elasticity ; sensibility to ZIRCONION. 263 the magnet ; susceptibility of the welding process, and of acquiring, by a union with carbon, silicon, or aluminium, the capability of hardening by being suddenly refrigerated from a red-heat ; also of being hardened by the hammer, and of being restored by heat in the annealing process. 1412. The metals remarkable for permanency of lustre, are gold, plati- num, iridium, palladium, rhodium and nickel, called on that account noble, or perfect. Those principally remarkable for malleability, are gold, silver, platinum, copper, palladium, nickel, iron, tin, cadmium, and lead. Among these, iron and platinum only, can be advantageously hammered at a very high temperature. 1413. The metals distinguished for elasticity, are iron, copper, and silver. Iron, in the state of steel when duly tempered, is pre-eminent for this property. 1414. The metals remarkable for ductility, are gold, iron, either pure, or as steel, silver, copper, platinum, tin, and lead. In large rods or pipes, lead and tin are the most ductile. 1415. The magnetic metals are iron, whether pure, in the state of steel, or in that of protoxide, nickel, and cobalt. Those susceptible of the weld- ing process, are iron and platinum. Iron only is capable, of uniting with carbon, silicon, or aluminium, and hardening consequently by quick re- frigeration. Gold and platinum are distinguished by their superior gravity, which is between two and a half, and three times as great as that of iron, tin, or zinc. 1416. All the metals have a specific gravity greater than five, if we ex- cept those of the earths and alkalies. 1417. Of the Annealing Process. Malleability, ductility, and tough- ness, in metals susceptible of the annealing process, are probably dependent on the quantity of caloric remaining in combination with their particles, while in the solid state. When malleable metals are hammered, they give out heat, and become harder, more rigid, elastic, and dense, until they ac- quire a certain maximum of density. This being attained, they are frac- tured if the hammering be carried further. Exposed to the fire until softened, they are found on cooling to liave regained the properties of which percussion had deprived them ; and they may be again condensed, heated, and hardened, by the hammer. 1418. Of Alloys. This name is given to the compounds formed by the union of different metals. There is always copper in gold and silver coin; and in the metal employed under those names by the smiths and jewellers, there are various proportions of the baser metal. Brass consists of copper and zinc ; pewter, of lead and tin, or of tin, copper, and anti- mony. Of the Oxidalility of Metals by Exposure to Air or Moisture, with or without Heat. 1419. Gold, silver, platinum, palladium and rhodium, do not become oxi- dized by exposure to water or oxygen at any temperature ; and when oxi- dized by other means, on being ignited are reduced.* * The verb to reduce, has long been employed by chemists to signify the deoxi- dizement of a metallic oxide, so as to effect its restoration to the metallic state, or that of a regulus, to use another word which I shall also employ, to avoid circumlo- cution; although it is now somewhat antiquated. The verb to revive has been used in the same sense as to reduce. 264 INORGANIC CHEMISTRY. 1420. Iron, zinc, and tin are not oxidized by exposure to dry air, or to water alone, unless aided by a red-heat. Of these metals iron is most acted upon by the joint influence of air and moisture, at the ordinary tem- peratures of the atmosphere. Copper, tin, and lead do not decompose water at any temperature, but are oxidized at a red-heat, or at temperatures sufficient for their fusion. Mercury is not oxidized by water under any circumstances. It is oxidized by agitation, or by a heat just below its boiling point, with access of air; but when distilled, it abandons the oxygen which may have united with it previously. OF METALS OF THE EARTHS PROPER. 1421. The metals included under this head are alumi- nium, glucinium, yttrium and thorium. SECTION I. OF ALUMINIUM. 1422. A chloride of aluminium was obtained by Oersted, by subjecting to a current of chlorine, an intimate mixture of alumina and carbon, heated in a porcelain tube. The affinity of the carbon for the oxygen of the earth, and of the chlorine for the metallic radical, was productive of car- bonic oxide in the state of gas, and the chloride of alu- minium in the state of vapour; of course the former escapes, while the latter condenses, within a glass tube purposely luted to that in which the materials are ignited, as already explained. 1423. By heating, with potassium, the chloride obtained by the process above mentioned, Wohler liberated alumi- nium through the superior affinity of potassium for chlo- rine. 1424. I have repeated this process so far as to obtain the chloride, and to expose it to reaction with potassium, but I found it difficult to extract the aluminium from the residual mass to a satisfactory extent. 1425. Properties of Aluminium. In the state in which Wohler obtained this metal, it is described as a gray pow- der much resembling that of platinum. Some little facets, which have sufficient magnitude to be distinguished, after compression under the burnisher, display a metallic bril- liancy. Yet in the pulverulent form, the metal has so little power to conduct electricity, that, when interposed in the galvanic circuit, it interrupts the action. It is alleged, however, that, in a minute state of division, iron is a non- ALUMINIUM. 265 conductor of electricity, and Turner states that, by fusion, aluminium becomes a conductor. It appears to me that at best its claims to the metallic character are not superior to those of carbon in the form of plumbago. Its atomic weight is 14. 1426. Aluminium burns with a heat so intense, as to cause the fusion of the resulting oxide, which becomes, on cooling, hard enough to cut glass. Aluminium is not oxi- dized when water is evaporated from it at a gentle heat. At a boiling heat it evolves hydrogen feebly, and the evo- lution, having once commenced, continues for some time after refrigeration. With concentrated nitric or sulphuric acid, aluminium has no reaction at ordinary temperatures; but, assisted by heat, it forms a sulphate or nitrate, ac- quiring oxygen from one portion of the acid, and uniting with the remainder. When subjected to a solution of pot- ash, soda, or ammonia, aluminium, by the decomposition of the water, is converted into alumina, which unites with the alkali, forming an aluminate. On this account, in pre- paring aluminium, there should not be an excess of potas- sium; and any potash produced during the process, should be quickly removed by the employment of a quantity of water no larger than necessary. Of Alumina. 1427. This earth is found nearly pure in the gems called by jewellers oriental, and classed by Bronguiart, under the head of Corindon Telesie. The ruby, sapphire, amethyst, and topaz, of the most beautiful kinds, are thus designated. Of all stony minerals they have the highest specific gra- vity, and are only inferior to the diamond in hardness. Differing from each other only in colour, they yield by ana- lysis little else than pure alumina. There are other jewels of the same name and colour, which ought not to be con- founded with those here alluded to. As an ingredient in clay, which owes its plasticity and all its striking qualities to alumina, this earth enters largely into the structure of the terrestrial globe. 1428. The spinelle ruby, a precious stone, and Gahnite, are aluminates, the former of magnesia, the latter of zinc; in which, however, there are six times as many atoms of alumina, as of the other constituent. 34 266 INORGANIC CHEMISTRY. 1429. There are two native forms of hydrate of alumina; one found in the United States, in the form of a stalactite, white and semitransparent, called Gibbsite; the other in Siberia, called disapore, from the property of flying into pieces, or even powder, when heated, in consequence, no doubt, of the vaporization of the combined water. 1430. Preparation. Berzelius alleges that the alum of commerce, if it contain oxide of iron, should be dissolved and recrystallized several times; or a solution being made and allowed to stand for some time, the oxide of iron is precipitated in yellow flocks. To the solution of alum at a boiling heat, a solution of carbonate of potash is to be added in excess, and the whole is to be digested at a mo- derate temperature, to decompose any supersulphate of alumina which the alkali may have precipitated. The precipitate, after having been collected and well washed upon a filter, is to be redissolved in chlorohydric acid, and precipitated by an excess of ammonia, either caustic or carbonated. This second precipitation is necessary, to get rid of a portion of carbonate of potash, with which the alumina forms a triple combination which cannot be decomposed by water. The precipitate produced as last mentioned, is to be collected and carefully washed. When dried it forms a hydrate, which, by a red heat, is con- verted into pure alumina. One hundred parts of alum yield a little more than ten of the earth. 1431. In France a species of alum is used, in which ammonia takes the place occupied by potash in the com- mon alum. By heat, which expels the acid and alkali, pure alumina may be extricated from this compound. 1432. Properties. Alumina is white, plastic when mois- tened, soft to the touch, adherent to the tongue, inodorous, insipid, and infusible in the furnace. It is the only earth which was fused before the compound blowpipe was in- vented. Its property of contracting and hardening by heat, was noticed when on the subject of Wedgwood's pyrometer. 1433. It is remarkable that, although quite insoluble in water, this earth abstracts and retains a quantity of water amounting to 15 per cent, of its weight. It is on this account that, as an ingredient in clay, its influence on vegetation is so beneficial. During rains it becomes sa- ALUMINIUM. 267 turated with moisture, which it slowly relinquishes in dry weather. 1434. There is a remarkable difference in the appear- ance of the hydrate of alumina as obtained by precipitation from a concentrated, or a weak solution of alum. In the former case it is a white, friable, spongy powder, which is adherent to the tongue, and, by exposure to a red-heat, parts with all its water. In the latter it forms a transpa- rent yellow mass, which breaks by the heat of the hand with a smooth and conchoidal fracture, does not adhere to the tongue, or swell by the addition of water. In this state, the hydrate of alumina does not part with all its water, even at a temperature above that of redness. 1435. Alumina has a great affinity for vegetable colour- ing matters, which it consequently precipitates from their solutions, forming the pigments known under the name of lakes. 1436. This earth and its salts are of great use in dye- ing, as mordants to cause the dyes to adhere. The latter, in many cases, have no affinity for the organic fibres which are to be dyed; but the alumina, combining with both the dye and the fibre, associates them permanently. 1437. Alumina is soluble in solutions of caustic potash and soda, and even in those of baryta and strontia, but dissolves in liquid ammonia, only to a very small extent. Alumina has an affinity for oxybases so strong, as to be considered as acting the part of an acid in some instances. With the acid and base of alkaline carbonates it forms triple compounds, which will bear a low red-heat without expelling the acid, or producing a more intimate union between the earth and alkali. 1438. The affinity of alumina for magnesia is so strong that when separated simultaneously from a common sol- vent, the former cannot be taken up entirely by the alkali, by which the separation is effected. If magnesiferous alumina, after having experienced a red-heat, be subjected to chlorohydric acid, a white powder remains, which is an aluminate of magnesia. - 1439. Three properties serve to detect alumina; first, its affinity for potash, and consequent solubility in a solution of that alkali ; secondly, the property which it has of form- ing with sulphuric acid and potash, alum, so readily recog- nised by its crystallization and taste; thirdly, the property 268 INORGANIC CHEMISTRY. of producing a fine blue colour, when moistened with nitrate of cobalt, and exposed to a strong heat. 1440. In the habitudes of this substance, we have an exemplification of the commutable character of electro- chemical characteristics. While w r ith the alkalies and al- kaline earths it performs the part of an acid, with various acids it acts as a base, forming with them compounds, both natural and artificial. Among the former is the mineral generally designated as feldspar, which is com- posed of silicate of alumina, and silicate of potash. Porce- lain is an artificial silicate of alumina. Its existence as a base in alum has been mentioned. 1441. Alumina was named from alumen, the Latin ap- pellation for alum. The specific gravity of alumina is 2. It is composed of two atoms of aluminium, equivalent 28, and three atoms of oxygen, equivalent 24 = 52. It is, therefore, a sesquioxide. Experimental Illustrations. 1442. Alumina, precipitated from a solution of alum by an alkali. Rendered blue by a solution of nitrate of cobalt. Contraction sustained by exposure to heat, illustrated. Of Chloride of Aluminium. 1443. The chloride of aluminium is obtained as I have stated above. (1422.) It is partially translucid, lamellated in structure, of a greenish- yellow colour, and an astringent taste. Litmus is reddened by the action of this chloride. It dissolves in water with a hissing noise. When the solution is highly concentrated, it deposites crystals, which, being converti- ble by heat into alumina and chlorohydric acid, probably consist of one atom of chloride of aluminium, and one atom of water. According to Thenard, the chloride of aluminium forms, with the chlorides of potassium and sodium, compounds indecomposable by a red heat. These may be considered as formed by the union of a chloracid with a chlorobase. SECTION II. OF GLUCINIUM. 1444. Glucinium may be obtained from its oxide, glucina, by a process analogous to that above described for obtaining the radical of alumina. This metal resembles alu- minium in appearance, and in many of its properties, but differs from it in not being susceptible of oxidizement by a solution of ammonia, or by boiling water. YTTRIUM. THORIUM. 269 Of Glucina. 1445. Glucina is white and tasteless. It is insoluble in water, but forms with it a paste, which is somewhat adhesive, but not sufficiently so to be moulded. It does not harden by exposure to heat. 1446. It is soluble in the caustic fixed alkalies, but not in ammonia. It likewise dissolves in the alkaline carbonates, and in that of ammonia especially, by which it is distinguished from alumina, as well as by its incapacity to produce alum, or to as- sume a blue colour when treated with nitrate of cobalt. It forms also a fluacid, which, with the fluoride of potassium, precipitates from a hot solution in crystalline Slates, in the state of fluoglucinate of potassium (fluoride glucinico-potassique of erzelius). 1447. The equivalent of glucina is 26, being composed of one atom of glucinium, equivalent 18, and one atom of oxygen, equivalent 8. 1448. Glucina exists in the emerald, comprehending the beryl and aquamarine : also in the euclase. In consequence of the peculiar sweetness of its salts, it was named glucina, from y\vx.vs, sweet. SECTION III. OF YTTRIUM. 1449. Yttrium was procured by a process quite analogous to that described for alu- minium. It has a more metallic and crystalline aspect than that metal or glucinium. Its habitudes with oxygen and the acids are perfectly analogous to those of the me- tals above mentioned. It is liable to be slowly oxidized in a solution of potash by the decomposition of water. Like glucinium, it is not oxidized by water even when boiling. Of Yttria. 1450. Yttria is insipid, infusible, and insoluble in water. It is uncertain whether the yellow tinge which it usually presents, is appropriate, or produced by impurities. It is rendefed snow-white by the presence of a small quantity of sulphuric acid. It is heavier than baryta, being of a specific gravity approaching to 4.842. It is dis- tinguished from other earths by its insolubility in caustic alkalies ; while it dissolves in their carbonates, especially that of ammonia, although in a lesser quantity than glucina. 1451. Yttria is principally characterized by its susceptibility of precipitation by cyanoferrite of potassium (ferroprussiate of potash). Excepting thorina, this pro- perty is possessed by no other earth. 1452. With acids it forms salts, having a sweet taste, and in some instances the colour of the amethyst. In fact, the best means of detecting it, is the production with sulphuric acid of crystals having this hue, which are extremely slow to dissolve in water, and which effloresce when heated. Its affinities are more feeble than those of the alkalies or alkaline earths. 1453. This earth has been found only in three Swedish minerals, Gadolinite, yttro-tantalite, and yttro-cerite. 1454. Yttrium is composed v of one atom of yttrium, equivalent 32, and one atom of oxygen, equivalent 8 = 40. SECTION IV. OF THORIUM. 1455. Thorium was first found, not many years since, in a single locality, in the state of oxide or earth, combined with silicic acid. It is in the island of Loecun that it was met with, near the little village of Berwig, in Norway. It was found in a mineral resembling obsidian, and called thorite, which contained 57 per cent, of thorina, or oxide of thorium, and in addition, lime, magnesia, iron, manganese, os- 270 INORGANIC CHEMISTRY. mium, lead, tin, and a little alkali combined with silicic acid and water. In making the analysis of this mineral, Berzelius discovered thorina. 1456. From chloride of thorium, as from the other chlorides of the same metallic genus, the radical may be evolved by means of potassium and heat. It may like- wise be extricated from the double fluoride of thorium and potassium, or fluothorate of potassium. Thorium, in its appearance and in many of its properties, much re- sembles aluminium ; but differs from it in not being oxidized by reaction with boil- ing water, dilute sulphuric acid, or alkaline solutions. When heated gently in the air, thorium inflames, and is converted into thorina. 1457. I do not conceive that either thorium, or any other of those substances enu- merated as convertible by oxidizement into the earths proper, are more entitled to be considered as metals, than carbon in the state of plumbago. Of Thorina. 1458. Thorina is white, tasteless, and inodorous. In common with alumina, glu- cina, and yttria, it is capable of acting as a base with water. The resulting hydrate of thorina is by heat convertible into the anhydrous oxide, in a state of great hard- ness. 1459. Thorina may be known from its sulphate being more soluble in cold than in hot water. It is composed of one atom, of thorium, equivalent 60, and one atom of oxygen, equivalent 8 = 68. OF METALS OF THE ALKALINE EARTHS. 1460. Under this head are included magnesium, calcium, barium, and strontium. SECTION I. OF MAGNESIUM. 1461. Magnesium was first obtained by Bussy in 1829, by subjecting the chloride to the action of potassium, in a manner precisely similar to that already described for ob- taining aluminium (1422). It resembles silver in colour and fusibility. It is malleable, and has a decided metallic brilliancy. It is oxidized by exposure to the air, or to boiling water. When sufficiently heated in the air, it com- bines with oxygen, and is converted into magnesia. Its specific gravity is greater than that of water. Of Magnesia. 1462. This earth exists abundantly in a state of com- bination in nature. Dr. Thomson states that a whole range of low hills, consisting of anhydrous carbonate of mag- nesia, exist in India. 1463. Sulphate of magnesia is one of the salts which exist in the ocean, and, consequently, when sea water is evaporated in order to obtain common salt, the sulphate may be obtained from the mother-water. For the manu- CALCIUM, BARIUM, AND STRONTIUM. 271 facture of the salt first abovementioned, magnesia has been largely obtained in this country, from an American mineral called magnesite, which is silicate of magnesia, iron, and lime. Many varieties of lime-stone and marble contain magnesia. The marble called dolomite, is especially well known as a compound of lime and magnesia. The pre- sence of magnesia renders a carbonate less ready to give out carbonic acid gas. 1464. This earth may be precipitated from a solution of Epsom salt, by adding a solution of potash or soda. It may likewise be obtained from the carbonate by heat. 1465. Properties. Magnesia is white, has a feeble alka- line taste, and affects vegetable colours like an alkali, though feebly. (1070.) It is nearly insoluble in pure water, but dissolves to a considerable extent in water containing carbonic acid, forming a soluble supercarbonate. 1466. Magnesia is distinguished from the other alkaline earths, not only by being less energetic in its affinities and alkaline properties, but by the solubility of its sul- phate. 1467. Magnesia is one of the most fixed and refractory substances in nature, and was deemed infusible until fused by me in 1801, with the aid of the compound blowpipe. The specific gravity of magnesia is 2.3, and its equiva- lent, 20. Experimental Illustrations. 1468. The precipitation of magnesia from a solution of Epsom salt; exhibited; also its effects upon vegetable colours. SECTION II. OF CALCIUM, BARIUM, AND STRONTIUM, THE METALS OF THE THREE PRE-EMINENTLY-, ALKALINE EARTHS. 1469. These metals are so much alike in their habi- tudes, that I deem it expedient to treat of them under one head. Their oxides constitute three of the four earths distinguished as alkaline, which are pre-eminent in alka- linity. (1070.) Next to oxygen, silicon, and aluminium, 272 INORGANIC CHEMISTRY. calcium is probably the most abundant element in the crea- tion. Barium is comparatively a rare product, and stron- tium, as an ingredient in our globe, is still more sparsely distributed than barium. Neither exists excepting in com- bination, and for the most part in the state of oxide, in union with an inorganic acid, especially carbonic and sul- phuric acid. Of the Evolution of Calcium, Barium, and Strontium. 1470. In the last edition of this Compendium, it was mentioned, upon the authority of some of the most ap- proved treatises of chemistry, that Davy had isolated calcium. During the winter of 1838, being engaged in some efforts for obtaining the metal abovementioned, I was induced to re-peruse the original lecture in which the distinguished chemist above named described the result of his attempts to isolate the metals in question. 1471. It should be known, that by Seebeck, and by Ber- zelius, and Pontin, amalgams had been obtained of cal- cium, barium, and strontium. From the amalgams thus discovered, Davy undertook to distil the mercury ; but he frankly declared that he was in nowise certain that he had succeeded in this object. In the case of calcium, in his "most successful" experiment, "the tube broke and the metal took fire" before the process was completed. Sub- sequently to the date of these facts, as far as I have been enabled to learn, neither Davy nor any other manipulator has succeeded in making a less abortive experiment than that in which he was most successful. This- justifies the idea, that there has been some inherent difficulty which could not be overcome by the means to which he resorted. Agreeably to my experience, the weight of sixty grains of mercury, which is the quantity which he alleges himself to have employed, cannot, by the most powerful apparatus, be made to take up a sufficiency of calcium to leave a perceptible quantity of this metal when the mercury is dis- tilled from the aggregate. And I fully concur with Davy in the opinion, that the temperature requisite to drive mercury from an amalgam, either of calcium, of barium, or of strontium, is higher than glass will bear.* * To enable the reader to judge of the justice of my remarks respecting the claims advanced by Davy, I will here quote his own language. " That to obtain a complete decomposition was extremely difficult, since nearly a LIME, OR CALCIA, THE OXIDE OF CALCIUM. 273 1472. Having in my treatise on galvanism, or voltaic electricity, given an engraving and description of my ap- paratus, and an account of rny process for the evolution of the metals in question, I shall here only quote a few words respecting their properties as observed by me. 1473. " Either metal was rapidly oxidized in water, or in any liquid containing it; and afterwards, with tests, gave the appropriate proofs of its presence. They all sank in sulphuric acid ; were all brittle and fixed ; and, for fusion, required at least a good red-heat. After being kept in naphtha, their effervescence with water was, on the first immersion, much less active. Under such circum- stances they reacted, at first, more vivaciously with hydric ether than with water, or even chlorohydric acid ; because in these liquids a resinous covering, derived from the naph- tha, was not soluble, while to the ether it yielded readily." SECTION III. OF LIME, OR CALCIA, THE OXIDE OF CALCIUM. 1474. This oxide exists largely in nature in combina- tion with carbonic acid, forming all the varieties of marble and limestone. Some kinds of white marble, especially that of Carrara, so celebrated on account of its employ- ment in statuary, consist solely of this earth combined with water and carbonic acid, uncontaminated by any red-heat was required, and that at a red-heat the bases of the earths acted upon the glass, and became oxygenated. When the tube was large in proportion to the quan- tity of amalgam, the vapour of naphtha furnished oxygen sufficient to destroy a part of the bases ; and when a small tube was employed, it was difficult to heat the part used as a retort sufficiently to drive the whole of the mercury from the base without raising too highly the temperature of the part serving for a receiver so as to burst the tube." " When the quantity of amalgam was about fifty or sixty grains, I found that the tube could not be conveniently less than one-sixth of an inch in diameter, and of the capacity of about half a cubic inch. In consequence of these difficulties, in a multitude of trials I had few successful results; and in no case could I be absolutely certain that there was not a minute portion of mercury still in combination with the metals of the earths."* In a subsequent paragraph the distinguished lecturer adds : " The metal from lime I have never been able to examine exposed to air or under naphtha. In the case in which I was enabled to distil the mercury from it to the greatest extent, the tube unfortunately broke while warm, and at the same moment when the air en- tered, the metal, which had the colour of silver, took fire and burnt, with an intense white light, into quicklime."* * See Nicholson's Journal, Vol. XXI. for 1808; or, Tilloch's Philosophical Maga- zine, Vol. XXXIII. 35 274 INORGANIC CHEMISTRY. other matter. Hence, if the acid and water be expelled by heat, the lime will remain in a state of purity. Oyster- shells yield very pure lime by heating them to incan- descence. 1475. When impure carbonates of lime are exposed to a very high temperature, the matter constituting the impu- rities is prone to enter into intimate combination with the lime, impairing its causticity, and susceptibility of the slaking process. No doubt this arises from a diminution of affinity for water. The lime of shells is sometimes par- tially converted into a sulphide, by sulphur derived from the animal matter. 1476. The calcination requires more heat in a crucible, especially if covered, than in an open fire; and if the heat be too sudden, the carbonate may be fused without the expulsion of all the acid, which is afterwards more tena- ciously retained. The extrication of the carbonic acid is promoted by a current of steam, or of any other aeriform fluid. But steam is preferable, as it is more easily pro- cured, and cannot be productive of impurity. The ra- tionale is, that homogeneous aeriform particles interfere with each other more than heterogeneous, which, agree- ably to the Daltonian doctrine, to a certain extent oppose no resistance to reciprocal intermixture arid penetration. 1477. After the first calcination, Berzelius recommends that the lime be slaked, and again calcined in an open crucible. 1478. Properties. The colour, taste, and smell of this earth, are well exemplified in the best kinds of lime used in building (sometimes called quicklime), which is, strictly speaking, oxide of calcium, isolated from the water and carbonic acid usually united with it as found in nature. 1479. Quicklime has the property of combining, as a base, with water, acting as an acid. (826.) The water be- coming, in consequence, consolidated, abandons its latent heat, or caloric of fluidity. Hence great sensible heat is excited, and when the mass undergoing the change is large, ignition occasionally ensues. The lime is by these changes rendered pulverulent, and is said to be slaked. The process is called slaking. The slaked lime thus pro- duced, is by chemists called hydrate of lirrfe. (826.) Quick- lime is productive of heat, even when triturated with snow. 1480. Water takes up about Teeth of its weight of this LIME, OR CALCIA, THE OXIDE OP CALCIUM. 275 earth, forming lime-water. On this a pellicle is generated, soon after exposure to the air, by the union of the lime with the carbonic acid, which always exists in the atmo- sphere. 1481. In lime-water, some metallic oxides are soluble, especially those of lead and mercury. It follows, from the definition of acidity and basidity, that in the resulting com- pounds, the oxides of the metals proper act as acids, while that of calcium acts the part of a base. (629, &c.) The property which lime has of affecting vegetable colours, like an alkali, has already been noticed. (1065, &c.) Though lime is precipitated from the aqueous solution, known as lime-water, by carbonic acid, yet an excess of this acid being supplied, the precipitate is re-dissolved. It is in this way, no doubt, that the water in limestone coun- tries becomes charged with this earth. 1482. The hardening of mortar is ascribed by Berzelius to the affinity between the lime and the silicic acid in the sand. Hence the necessity of this ingredient. Experimental Illustrations. 1483. Characteristic changes produced in vegetable co- lours by the solution of the earth in water, called lime- water. A glass of lime-water is not made turbid by air from a bellows, but becomes so on propelling the breath through it. Absorption of carbonic acid by lime-water, shown. Solution of lime by an excess of the acid. Lime precipitated from solutions of its muriate or nitrate, by sulphuric or oxalic acid. Of Peroxide or Bioxide of Calcium. 1484. Oxygen is absorbed when passed over lime heated to incandescence. By adding lime-water to oxygenated water, acidulated with muriatic acid, Thenard procured crystals of bioxide of calcium. (853, &c.) Of Baryta. 1485. This earth was named from the Greek B*^?, heavy; because the minerals containing it are peculiarly heavy, when compared with other earthy substances. 276 INORGANIC CHEMISTRY. 1486. Preparation. To procure baryta, eight parts of the sulphate, finely pulverized, should be intimately min- gled with one of charcoal, and afterwards triturated with two parts of resin, sugar, molasses, or wheat flour. The mixture is to be kept at a white heat, in a Hessian cruci- ble, for three-quarters of an hour. 1487. The sulphate of baryta, by being deprived of oxy- gen, becomes converted into a sulphuret of barium, which yields a nitrate of baryta on the addition of nitric acid. The filtered solution by evaporation yields crystals of the nitrate, which should be decomposed in a porcelain or pla- tinum crucible. This operation is tedious; since the heat cannot be urged beyond a certain degree of intensity, without causing the salt to rise up in a foam, so as to overflow the crucible. If the heat be arrested at a certain stage of the process, Berzelius alleges that a portion of ni- trous oxide remains united with the earth, forming a com- pound which has been mistaken for bioxide (" suroxide") of barium. 1488. Neither the carbonates nor hydrates of baryta, or of strontia are, like those of lime, decomposable per se by heat. The addition of carbonaceous matter enables us to decompose them; as it changes the carbonic acid into carbonic oxide, which has no affinity for the earths, and, therefore, escapes. 1489. Properties. Baryta is acrid, slakes like lime, and is more soluble in water. It is more actively alkaline, both as respects its taste and its action on vegetable co- lours, than any other earth. It is gray at first, but ab- sorbs water and becomes white. Its aqueous solution is rendered milky by carbonic acid, and, by combining with it, becomes covered with a pellicle of carbonate, when ex- posed to the atmosphere. From its solution in boiling water, baryta crystallizes on cooling. 1490. Solutions of barium, whether in the state of a hydrate, acetate, nitrate, or chloride, are very useful as tests for sulphuric acid, which, combining with the oxide of barium (baryta), previously existing in the hydrate or ni- trate, or formed from the chloride by the decomposition of water, is precipitated by them from any liquid. 1491. Ignited intensely, it absorbs oxygen if exposed to it, and passes to the state of bioxide. This earth is poison- LIME, OR CALCIA, THE OXIDE OF CALCIUM. 277 ous. Its specific gravity is 4, and its equivalent, formed of one atom of barium = 69, and one of oxygen = 8 = 77. Experimental Illustrations. 1492. Baryta, free from water, exhibited; also in crys- tals, Barytic water rendered milky by the carbonic acid of the breath. Solutions of baryta, and of sulphuric acid, introduced into distinct vessels of pure water, have no effect; but portions mingled in the same vessel produce a cloud. Water, coloured by alkanet, turmeric, &c., changed by baryta, as by an alkali. Of Strontia. 1493. This earth is very analogous to baryta in its pro- perties and composition. It is distinguished from baryta, by the red colour which its solutions communicate to flame, by its crystallization, and by its being more soluble in boil- ing water and less so in cold. Excepting baryta, it is more actively alkaline than any other earth, both as re- spects taste and its action on vegetable colours. 1494. Strontia water is not like that of baryta precipi- tated by a dilute solution of the sulphate of potash, or that of soda, and when added to a solution of bichromate of lead its power as a precipitant is inferior. 1495. Strontia maybe obtained from the carbonate or sulphate, by a process in every respect similar to that which has been described as the means of procuring ba- ryta. 1496. The equivalent of this earth is 52. Experimental Illustrations. 1497. Turmeric, alkanet, and red cabbage, changed by strontia-water, as by alkalies. Red colour of the flame of alcohol, containing strontia, shown. Effects of the aque- ous solutions of the alkaline earths on a solution of bichro- mate of lead. Of the Peroxides or Bioxides of Barium and Strontium. 1498. When the protoxides of barium and strontium 278 INORGANIC CHEMISTRY. are heated in contact with oxygen gas, they absorb it, and are converted into bioxides. When an aqueous solution of these earths is added to oxygenated water, the bi- oxides of their metallic radicals are precipitated in a crys- talline form. 1499. It was by means of a bioxide of barium thus pro- cured, that Thenard was enabled to obtain oxygenated water. (853.) The bioxide of barium was dissolved in chlorohydric acid. By adding sulphuric acid, sulphate of baryta was precipitated, in which half of the oxygen of the bioxide was retained, the other half being left in combina- tion with the water of the solvent. This operation being repeated several times, the liquid became more and more surcharged with oxygen. Afterwards, the chlorine of the acid was precipitated by sulphate of silver, and the sul- phuric acid, thus introduced, by baryta. Finally, the bi- oxide being less susceptible of vaporization than water, this liquid was removed by evaporation in vacuo over sul- phuric acidi (399.) Thus isolated, the oxygenated water was ascertained to deserve the appellation of bioxide, being found to hold two equivalents of oxygen for one of hy- drogen. OF THE METALS OF THE FIXED ALKALIES, OR ALKALIFI- ABLE METALS, POTASSIUM, SODIUM, AND LITHIUM. SECTION I. OF POTASSIUM. 1500. The discovery of potassium and sodium was made by Sir Humphry Davy, in 1807, by exposing their oxides, potash, and soda, to the divellent influence of the Voltaic current. These metals were afterwards obtained more copiously, by subjecting the alkalies, in contact with iron in a divided state, to intense heat in a luted gun bar- rel. Latterly, they have been obtained, with still greater facility, by heating the carbonates intensely, while inter- mingled with charcoal.* * In Brunner's process, bitartrate of potash, or carbonized cream of tartar, which consists of carbonate of potash intimately intermingled with the residual carbon of the decomposed tartaric acid, is subjected to intense heat in a luted iron mercury bottle, some coarsely powdered charcoal being added. The potassium was conveyed into a copper vessel containing naphtha as it came over from the bottle. For this vessel, I have substituted an iron tube, which becomes finally full of the metal and a carbo- POTASSIUM. 279 1501. The alkaline metal, whether potassium or sodium, being volatile at any temperature above redness, is extri- cated in the state of vapour, and condensed in a part of the apparatus where the heat is below redness. 1502. Properties. Potassium, when newly cut, strongly resembles silver in appearance. It is malleable, and so soft at ordinary temperatures, as to be moulded between the fingers like wax. When cooled to 32% it becomes brittle, and exhibits, when broken, a crystalline fracture. It melts at 106, and is converted into vapour when heated to a little below redness. When exposed to the air at the ordinary temperature, it absorbs oxygen rapidly, and is converted into potash. This absorption is sometimes so active, especially when aided by friction, as to cause the inflammation of the potassium. I once lost half an ounce of potassium, in consequence of attempting to extricate it by dividing the containing bottle by a file; it took fire, and was entirely oxidized. The affinity of this metal for oxy- gen is so strong, that, when thrown upon water or ice, it combines with the oxygen; while the hydrogen takes up a certain portion of the potassium, and burns with a beauti- ful rose-coloured flame. Potassium is lighter than water, its specific gravity being only 0.86. It is a good conduc- tor of heat and electricity. Its atomic weight is 40. SECTION II. OF SODIUM. 1503. Properties. Sodium resembles potassium in its appearance, and in many of its properties. It retains its naceous mass, which sublimes during the operation. The tube is then removed, and the end nearest the bottle screwed into a tapering tube, while the other orifice is closed by a cap, into which it fastens by screwing. The tube is then placed vertically in a furnace, through the bottom of which the tapering tube extends so as to be out of the way of the heat. Under the orifice of this tube, a vessel may be placed con- taining some naphtha, to receive the potassium as it descends in globules, after fusion or condensation from the state of vapour. The last portions are not evolved before the fire in the furnace reaches a white heat. The principal source of disappoint- ment in Brunners process, is the failure of the luting. When this happens, the iron bottle is soon burnt through. I have found it advantageous to secure the iron bottle employed in this process, while supported vertically in the furnace, by a stout cylinder of the same metal, the whole resting upon an iron disk supported by bricks made of porcelain earth. By these means, I procured last winter, at one operation, more than six ounces of potassium, 280 SODIUM. softness and malleability when cooled to 32. A globule of sodium, thrown upon water, swims to and fro on the surface with great rapidity, absorbing oxygen, and evolv- ing hydrogen from the water; yet no inflammation ensues. This is probably owing to the rapidity of its motion, which, by bringing it in contact with successive portions of water, keeps the temperature below that which is ne- cessary to combustion ; since, when the water is thickened with a little gum, which tends to impede the motion of the globule, sodium burns with a brilliant yellow flame. The presence of an acid produces the same result. The affinity of sodium for oxygen, does not appear to be so strong as that of potassium; since, according to Thenard, it is not oxidized when exposed to dry atmospheric air, or oxygen. It melts at 194, and for volatilization, requires a higher temperature than potassium. 1504. Sodium forms a number of alloys with potassium; one of these remains fluid at 32, and is lighter than naph- tha. The specific gravity of sodium is 0.97223. It is a good conductor of heat and electricity. Its atomic weight is 24. Experimental Illustrations. 1505. The inflammation of potassium and sodium upon water and ice, exhibited; also the regeneration of the alkali, demonstrated by the usual tests. The decomposi- tion of potash, by iron card-teeth, heated to incandescence. Apparatus for its evolution, exhibited. Of Potash or Potassa, and Soda, the Protoxides of Potassium and 8 odium. 1506. A ley, obtained by the lixiviation of the ashes of inland plants, especially wood, when boiled down, yields the potash of commerce. Potashes ignited so as to de- stroy vegetable colouring matter and other impurities, again dissolved, and boiled to dryness, form pearlash. Pearlash, dissolved in water, boiled with lime to remove the carbonic acid, filtered, and boiled down to the consistency of moist sugar, dissolved in alcohol, and boiled down gradually, and, lastly, fused at a red-heat in a silver vessel, forms the pot- ash, or, more strictly, the hydrate of potash of chemists. If, as soon as the alcohol has escaped, the residual mass SODIUM. 281 be refrigerated, it crystallizes. After fusion at a red-heat, the alkali contains about 20 per cent, of water, existing in it as an acid, and of which, per se, it cannot be deprived by heat. 1507. Pure carbonate of potash may be procured from bitartrate of potash, whether carbonized by heat, or defla- grated with pure nitre, by subjecting the residue to water, and the resulting solution to heat, to vaporize the solvent. 1508. To obtain pure potash, or in other words, to re- move carbonic acid from the alkali of a carbonate, Berzelius advises the addition of one and a half parts, by weight, of pure hydrate of lime, to one part of a pure carbonate, ob- tained as abovementioned v dissolved in a cauldron, and kept boiling. The lime is not to be added at once, but gra- dually; as without this precaution, the resulting carbonate of lime retains, like a sponge, a great part of the alkali. The liquid is to be tested by an acid or by lime-water, until it ceases to indicate the presence of carbonic acid. After this, it may either be kept in a liquid state, or evapo- rated till it crystallizes, and preserved in crystals ; or being ignited till it becomes fused, and poured out on a slab, or into moulds, it may be preserved in the state of hydrate. 1509. I have used for the purpose last mentioned, the moulds usually employed for casting musket balls. The spherical form presenting the least surface in proportion to the mass, is favourable to the preservation of a sub- stance liable to be deteriorated by contact with the atmos- phere. 1510. The crystals of potash, thus procured, are always free from carbonic acid, and if derived from a pure carbo- nate, excepting water, may constitute pure potash. But when pearlash is the carbonate employed, alcohol must be resorted to, after the caustic ley has been evaporated to the consistency of moist sugar, in order to get rid of the impurities. This liquid combines with the pure potash, while a portion of water contained in, or formed from, the alcohol, separates from it in union with the impurities. 1511. Soda is obtained from the ashes of certain plants which grow on the sea-shore, as potash is by the incinera- tion of those which grow inland. It is procured also from chloride of sodium, and sulphate of soda. 1512. Soda is purified, and procured in the state of hy- 36 282 INORGANIC CHEMISTRY. drate, or in crystals, by a process analogous to that above described for its kindred alkali. 1513. Properties of Potash and Soda. Potash and soda are of a grayish-white colour, and, in common with other alkalies, have a peculiar taste. They render tincture of turmeric brown, syrup of violets green, and alkanet blue. Colours changed by acids, are restored by them. They are the opposites of, and antidotes to, acids, and capable of forming with them neutral compounds, or, in other words, such as are neither acid or alkaline. They are incor- rectly said to render vegetable blues green, as if this were universally true. Alkanet is made blue by them, while neither litmus nor indigo is rendered green. (1065, &c.) 1514. Although potash is more soluble than soda, and is deliquescent, while soda effloresces; yet the salts of soda are more soluble than those of potash. Both cau- terize the flesh. Potash is the more active. Common caustic is an impure hydrate of this alkali. 1515. Crystallized potash contains four atoms of water to one of the oxide, of which three only can be expelled by heat. After fusion it may be called, however paradoxical it may seem, an anhydrous hydrate, though not an anhy- drous oxide. Both potash and soda fuse when subjected to a red-heat. The atomic weight of potash is 48, that of soda, 32. The hydrate of potash consists of one atom of alkali, and one of water. 1516. Potash may be distinguished from soda, by its forming salts nearly insoluble in water with tartaric, or oxychloric acid ; while those formed by soda with the same acids are soluble. Chloroplatinic acid causes a yellow precipitate with potash, but not with soda. Experimental Illustrations* 1517. Characteristic changes produced in vegetable infu- sions, as in previous illustrations. (1075.) 1518. To a saturated solution of potash and soda, or their carbonates, a saturated solution of tartaric acid being added in excess, crystals are yielded by the potash only. Into different salts of the two alkalies in solution, chioro- platinic acid being poured, a yellow precipitate distinguishes the potash. SODIUM. 283 Of the Peroxides and Suloxidcs of Potassium and Sodium. 1519. Peroxide of potassium is produced by the combustion of potassium on a plate of silver in oxygen gas, in which case the metal acquires three times as much oxygen as it holds in the state of potash. The peroxide is also obtained when nitre is intensely heated, or when potassium is deflagrated with nitre. 1520. Two parts of sulphate of potash, ignited intensely with one of lampblack, give a pyrophorus which takes fire spontaneously with scintillations in the air. This arises, no doubt, from the extreme state of division in which carbon, potassium, and sulphur exist in the residual mass. 1521. The peroxide of potassium is of a greenish-yellow colour, and possesses most of the properties of the protoxide, excepting that of acting as a base. When brought in contact with water or acids, it is decomposed into potash and oxygen. 1522. The peroxide of sodium is of a greenish-yellow colour also, and, in its pro- perties, is analogous to the peroxide of potassium, except that at a high temperature it abandons part of its oxygen, and is converted into protoxide. It cannot, there- fore, be obtained by burning sodium in an excess of oxygen; since the heat produced by the combustion, would decompose the peroxide, if already formed. In order to procure it, it is necessary to heat soda in contact with oxygen. The peroxide of so- dium contains one and a half atoms of oxygen, united to one of metal. 1523. Berzelius mentions that-suboxide of potassium may be obtained by heating the metal in a quantity of oxygen inadequate for its saturation; also by exposing to a temperature of about 40 F., a mixture of hydrate of potash and potassium, in equi- valent proportions; in which case the metal is oxidized at the expense of the com- bined water, the hydrogen escaping. The anhydrous protoxide may be obtained in like manner, by heating potassium with a greater quantity of the hydrate. Turner alleges, however, that the suboxide of potassium is generally regarded by chemists as nothing more than a mixture of potassium and potash. 1524. According to Berzelius, a suboxide of sodium may be obtained by the same means as the suboxide of potassium, substituting the one metal for the other. The same uncertainty, however, prevails with regard to it, as with regard to the suboxide of potassium. 1525. When potassium or sodium is heated in ammonia, it combines with nitrogen and liberates hydrogen, and the resulting nituret absorbs ammonia; so that we have a combination of two binary compounds of nitrogen, which may possess, to a small extent, the relation of acid and base. There are, however, no phenomena in che- mistry which are more anomalous than those which are associated with the produc- tion and evolution of this compound. Nevertheless, as its nature is unintelligible even to adepts, I shall not present the details here. 1526. I hinted, when entering upon the subject of nitrogen, that it would be seen in the sequel, that it was not destitute of pretensions to a place in the basacigen class. It was in reference to the phenomena above alluded to, that I made that re- mark. 1527. If nitrogen form the common ingredient in two compounds, one electro- negative, the other electro-positive, which combine to form a third, it fulfils the con- dition of a body producing both an acid and a base, and is of course a basacigen body. Yet it has already been pointed out that there is no class, of which some of the members do not display properties which might cause them to be placed in ano- ther class. Of Pfiosphurct of Potassium. 1528. Phosphorus and potassium, heated together in nitrogen or hydrogen gas, combine with the phenomena of combustion. In phosphuretted hydrogen, potassium burns, combining with phosphorus, and liberating the hydrogen. 1529. This phosphuret decomposes water, but, according to Berzelius, the gas evolved does not inflame spontaneously. Of the Compounds of Potassium with Carbon, Boron, and Silicon. 1530. The black matter which remains after the distillation of potassium, as ob- tained by Brunner's process, is alleged by Berzelius to be a pcrcarburet of potassium. When moistened it inflames, no doubt by decomposing water, and evolving potassu- retted hydrogen. The black matter which obstructs the tube used in the evolution of potassium by the process above mentioned, is also held to be a carburet. (1501 ) 1531. These carburets I have found useful in purifying naphtha, by its distillation with them. After undergoing this ordeal, potassium may be kept in it with less ap- 284 INORGANIC CHEMISTRY. pearance of reaction. I am under the impression that the carbon which remains in the iron bottle, is imbued with potassium, possibly in a state of chemical union. This may be used likewise for the purification of naphtha. 1532. It appears that, during the reduction of boric acid by potassium, a loruret is formed; since a portion of the mass evolves a gas on being moistened, which has not the smell of pure hydrogen. It is probably boruretted hydrogen. 1533. A siliciuret of potassium is obtained during the decomposition of fluosilicic acid gas. A portion of the liberated silicon, combining with potassium, forms the compound in question. This, on being moistened, gives off hydrogen, which has a peculiar odour resembling that of phosphuretted hydrogen. The analogy between these results and those mentioned in reference to boron, is obvious. SECTION III. OF LITHIUM. 1534. A fixed alkali was discovered, in 1818, by Mr. Arfwedson, to exist in small proportion, as an ingredient in a mineral called petalite. He af- terwards discovered it in two other minerals, called spodumene and lepido- lite. Allusion to this alkali, and the origin of its name, was made under the head of Ammonia. (1081.) 1535. By the influence of the Voltaic pile, decided indications have been obtained of the existence, in lithia, of a metallic radical. To this the name of lithium has been given. Lithium resembles sodium in appearance. Its atomic weight is 6. Of Lithia. 1536. Lithia, known only in the state of hydrate, is white, caustic, and has all the attributes of an alkali. When lithia, whether in the state of carbonate or uncombined, is heated in contact with platinum, the metal is at- tacked, and a compound is formed, which, according to Thenard, probably consists of the oxide of platinum, united to the oxide of lithium, and must of course be a platinate of lithia. Lithia is composed of one atom of lithium, equivalent 6, and one atom of oxygen, equivalent 8 = 14. 1537. Lithia is less soluble in water or alcohol than soda or potash. Its carbonate is less soluble in water than the carbonates of those alkalies. The chloride of lithium is deliquescent, and soluble in alcohol, the phos- phate of lithia is insoluble in water; in which respects these compounds differ from the corresponding combinations, formed by the other fixed alka- lies, or their radicals. Of the Reaction of Chlorine, Bromine, Iodine, Fluorine, and Cyanogen, with the Metals of the Earths and Alka- lies. 1538. In a former edition of this work, it was mentioned that for aluminium, glucinium, yttrium, thorium, and mag- nesium, chlorine has not sufficient affinity to expel the oxygen from their oxides; and that it was only in the state of oxide that they could be subjected to the gas. LITHIUM. 285 It has been already stated, that Oersted ingeniously con- trived to enable chlorine to combine with aluminium, by the co-operating affinity of intermingled carbon for the oxygen with which, in the state of earth, this metal is united : also, that a similar process had been successfully employed to obtain the chlorides of glucinium, yttrium, thorium, and magnesium. The most important considera- tion, associated with the existence of these chlorides, is their susceptibility of decomposition by potassium, and the consequent isolation of their metallic radicals. 1539. When the oxides of calcium, barium, strontium, potassium, sodium, and lithium are heated in chlorine, these metals are converted into chlorides, the oxygen being dis- placed. Potassium and sodium burn actively in chlorine, and it appears probable that any of the metals of the al- kalies or alkaline earths may, with heat, if not without, be directly combined with any of the halogen bodies. The same combinations may be obtained in the wet way by complex affinity, on presenting their oxides to the acids formed by these bodies with hydrogen. 1540. The chlorides of the metals of the alkalies, and of the alkaline earths, are all soluble, and some of them deliquescent. When in solution, they contain the same elements as if they were chlorohydrates of oxybases; and are, therefore, considered as such by some chemists. 1541. The difference between a chloride in solution and such a chlorohydrate, is rendered evident by setting down the ingredients agreeably to both suppositions, as fol- lows: Chlorine, hydrogen. Oxygen, metal. Chlorohydric acid. Oxide. Chlorohydrate. Oxygen, hydrogen. Chlorine, metal. Water. Chloride. ~v Dissolved Chloride. 286 INORGANIC CHEMISTRY. 1542. The soluble chlorides produce white precipitates in solutions of silver, lead, or black oxide of mercury. They do not deflagrate with charcoal, nor do they, like sulphates, after being heated with it, yield the odour of sulphuretted hydrogen on being moistened. 1543. The soluble chlorides of the metals of the alkaline earths and alkalies, excepting that of magnesium, are, by heat, converted into anhydrous chlorides, easily detected by the fumes which they give with sulphuric acid. 1544. Bromine, like chlorine, when heated with any of the fixed alkalies, or alkaline earths, except magnesia, dis- places the oxygen and combines with the metallic radical. Like chlorine also, it does not, per se, produce this effect either with magnesia or the earths proper. 1545. The affinities of iodine are, in most cases, less energetic than those of chlorine or bromine. Potash and soda are the only oxides of the metals of the earths and alkalies, from which iodine can, with the assistance of heat, expel the oxygen, in order to combine with their metals. 1546. The bromides and iodides, when combined with water, may, like the chlorides, be regarded either as in a state of solution, or as bromohydrates and iodohydrates. The bromides may be recognised by the red vapours which arise, when they are heated in a tube with the bisulphate of potash. Similar vapours would be given out by the nitrites, if treated in the same way; but the bromides may be distinguished from those salts, by their not deflagrating when thrown on incandescent coals. 1547. An iodide may be detected by dropping a portion into sulphuric acid, heated nearly to the point of ebullition. (738.) By these means iodine, if present, will be made ap- parent in the form of a violet vapour. Iodine is also dis- placed from its combinations by chlorine; and, when these, previously to the addition of chlorine, are mingled with a paste made of starch, a blue colour is produced. It is alleged that sea salt sometimes contains a quantity of iodine adequate to produce this result. 1548. Berzelius states that, when potassium is heated in cyanogen, it is converted into a cyanide; also that the habitudes of sodium are in this respect similar. It is pro- bable that the same result would ensue with all the metals LITHIUM. 287 of the alkalies and alkaline earths. Cyanogen is usually generated by the reaction of potash with animal matter, which deoxidizes the alkali, and at the same time furnishes to it the elements of cyanogen, which, in consequence, simultaneously unite with each other and with the metal, forming a cyanide of potassium. 1549. When the cyanoferrite of potassium (ferroprus- siate of potash) is intensely heated, the cyanoferric acid is decomposed. The cyanide of potassium remains mingled with a carburet of iron, and may be extricated by solution, filtration, evaporation, and crystallization. Subjecting the cyanoferrite of sodium to a similar process, the cyanide of sodium may be obtained. (1299, &c.) 1550. The cyanides may be detected by their power of producing a blue colour with solutions of the peroxide of iron; also by evolving the odour of peach blossoms, when subjected to chlorohydric acid. 1551. It is highly probable that the reaction of fluorine with the metals of the earths and alkalies, will prove to be analogous to that of chlorine. The fluorides, however, differ much from the chlorides in solubility. Some varie- ties of the fluoride of calcium constitute Derbyshire spar, while the chloride of calcium is a deliquescent salt. 1552. The presence of fluorine in a mineral may, in a majority of instances, be detected by the following process. Let a small portion of it be pulverized, and subjected to heat with about twice its weight of concentrated sulphuric acid, in a leaden, silver, or platinum cup. Let this cup be covered by a glass plate, coated with beeswax, through which some letters have been traced so as to denude the vitreous surface. After exposure for half an hour, aided by as much heat as can be used without melting the wax, the glass should be relieved from its coating and examined. Then, if the portions of the vitreous surface, exposed to the fumes, prove to be so corroded as to render the cha- racters traced through the wax distinguishable, the pre- sence of fluorine may be inferred. 1553. Berzelius informs us that when this principle is in combination with silicon, it will not act on glass. Hence he advises that the mineral, suspected of containing fluo- silicic acid, should be subjected to the flame of the blow- pipe, at one end of a glass tube, of which both ends are open ; so that the fumes produced may be impelled by the 288 INORGANIC CHEMISTRY. blast through the tube from one orifice towards the other. By these means, milky spots will appear on the glass, in consequence of the condensation of water containing fluo- silicic acid, if this be an ingredient in the mineral. Of the Reaction of Sulphur, Selenium, and Tellurium, with the Metals of the Earths and Alkalies. 1554. Sulphur unites with all the metals of the alkalies and alkaline earths, so far as the experiment has been tried, whether presented to them in the metallic state, or in that of oxide. Its power of reducing their oxides is greater than that of any other basacigen body; as when present in excess, it acts by its affinity for the oxygen and the metal. (523, &c.) The affinity of the halogen bodies for oxygen, is so inferior to that of sulphur, that when oxygen is expelled from oxides by one portion of them, it does not combine with another, however great the excess in which they may be present. 1555. Sulphides (sulphurets) are also formed by deoxi- dizing the sulphates by carbon or hydrogen with the aid of heat, (1436, 1437,) by boiling in water equivalent weights of sulphur and the earth or alkali to be com- bined; or by passing sulphydric acid into water, holding the oxide in solution or suspension. When this is done under favourable circumstances, the metal is converted into a sulphobase by the sulphur of one portion of the acid ; while the compound thus formed unites with another portion of the acid, forming a sulphosalt, denominated a sulphydrate. This view of the subject we owe to Berzelius, who has shown that sulphur, selenium, and tellurium, all have the property of forming acids with one set of radicals, and bases with another; and that the sulphacids and. sul- phobases thus formed, are capable, like oxacids and oxy- bases, of forming compounds which he considers as sulpho- salts, or salts in which sulphur performs a part analogous to that which oxygen performs in oxysalts, such as the sulphate or nitrate of potash. 1556. Formerly it was supposed that, when absorbed by an alkaline solution, sulphydric acid (sulphuretted hydro- gen) combined with the oxybase, forming what was called a hydrosulphuret. It was also supposed that a sulphide of an alkalifiable metal, by solution in water, would be con- verted into an oxybase by the oxygen of the water; while LITHIUM. 289 the hydrogen, with a double proportion of sulphur, form- ing hisulphuretted hydrogen, would combine with the oxy- base. 1557. Through the sagacity and industry of Berzelius, much knowledge has of late years been acquired respect- ing the combinations of sulphur with the alkaline metals. He mentions seven compounds, in which, supposing the quantity of the potassium in each to be the same, the quan- tities of the sulphur are severally 1, 2, 3, 3, 4, 4^, 5. 1558. To remember the details respecting the prepara- tion and characteristics of these sulphides, would be too great a burthen for the memory of those who are not so situated as to take a particular interest in them. 1559. Sulphides of the metals of the earths and alkalies, on being moistened with water, evolve sulphydric acid, and produce this result still more actively on being subjected to chlorohydric acid. 1560. The selenides of the metals of the earths and alkalies may, in most cases, be produced by heating the metal with selenium. The selenides of these metals bear a great resemblance to the sulphides, and when heated are reduced to the metallic state, producing the smell of horse- radish. 1561. The tellurides are but little known, and, except so far as they act as telluracids or telluribases, so as to give pretensions to tellurium to be placed among the basa- cigen elements, they are uninteresting. Experimental Illustrations. 1562. Sulphides in solution exhibited. Earths precipi- tated by acids. OF METALS PROPER. 1563. The metals included under this head, are gold, platinum, silver, mercury, copper, lead, tin, bismuth, iron, zinc, arsenic, antimony, palladium, rhodium, iridium, osmium, nickel, cadmium, chromium, cobalt, columbium, manganese, molybdenum, titanium, tungsten, uranium, cerium, and va- nadium. 37 290 INORGANIC CHEMISTRY. SECTION I. OF GOLD. 1564. Gold is usually found in nature nearly pure. It is not liable, like other metals, to be disguised by a union with oxygen or sulphur. The precipitate obtained from a solution of gold coin in aqua regia, by the green sulphate of iron, is pure' gold. This metal is also purified by exposure to heat and air, or by nitric acid, by which means baser metals are oxidized; as in the processes of cupellation and parting. 1565. From the sands, or ores, in which they exist naturally, minute portions of gold are collected by trituration with mercury, with which they amalgamate. The mercury is distilled from the amalgam thus obtained, by means of an iron alembic. 1566. Properties. The specific gravity of gold is 19.3, and its equiva- lent 200. Its colour and lustre are too well known to need description. It is the most malleable and ductile metal, and suffers the least by exposure to air and moisture. Gold leaf, which is about 1000 times thinner than printing paper, retains its lustre in the air. Gold leaf transmits a greenish light, but it is questionable whether it be truly translucent. Placed on glass, and viewed by transmitted light, it appears like a retina. It is erroneously spoken of as a continuous superfices. 1567. Gold fuses at a low white-heat, but requires the temperature pro- duced by the compound blowpipe, by galvanism, or by the explosive power of electricity, to volatilize or oxidize it. Its not being liable to tarnish by exposure, is due to the weakness of its affinity for oxygen or sulphur. 1568. When a solution of chloride of gold is mixed with sulphuric ether, the ether takes the metal from the chlorine, retaining it in solution. If iron or steel be moistened with this ethereal liquid, it is productive of a slight gilding. 1569. Phosphorus, carbon, and the baser metals, also hydrogen gas and its compounds, by a superior affinity for oxygen or chlorine, precipitate gold from the solution of its chloride in the metallic form. 1570. The abstraction of oxygen precipitates gold, by liberating the hydrogen of water. The hydrogen thus liberated, takes chlorine from gold, forming of course chlorohydric acid, which has no affinity for this metal, unless in the state of chloride. As oxygen is necessary to the base of an oxysalt, so chlorine is indispensable to the constitution of a chlorosalt. 1571. The union of gold with mercury, was adduced as an exemplifica- tion of simple chemical combination. (515.) The compound thus formed, when the ingredients are in due proportion, is of great use as the mean of that kind of gilding which is the most firm and durable. The affinity between the mercury and copper, renders it easy to coat with the amalgam the surface of any mass formed of this metal. Subsequently, the mercury may be driven off by heat, leaving a pellicle of gold upon the cupreous sur- face, which only requires burnishing, in order to display the colour and brilliancy of gold. 1572. With arsenic, gold combines energetically, absorbing this metal in the form of vapour, at a red-heat, without changing colour. Gold loses its malleability by acquiring yjo"th of its weight of arsenic. Probably gold may be united with all the metals. Phosphorus forms with it a brittle compound. GOLD. 291 1573. The affinity between chlorine and gold is pre-eminently energetic. A combination ensues, whether the metal be heated in the gas, or presented to it in aqueous solution, or in aqua rrgia, which is essentially a solution of chlorine in water. Aqua rogia is produced by the mixture of chlorohydric with nitric acid. It ought not, however, to be considered as a combination of them. As soon as the mixture is effected, a decomposition of both of the acids commences. 1574. One atom of nitric acid, by yielding three out of its five atoms of oxygen, (957,) can take all the hydrogen from three atoms of chlorine. (874.) Of course, three atoms of chlorine and one of nitric oxide are emancipated. If the acids employed be concentrated, both the nitric oxide and the chlo- rine are evolved ; but if there be a sufficiency of water, the chlorine remains in union with it, forming a more concentrated aqueous solution of chlorine than can otherwise be made. Excepting that it contains chlorine in a higher degree of concentration, which of course enables it to act with more energy, aqua regia does not differ, in its solvent powers, from a solution of chlorine in water. It cannot properly be considered as a distinct acid; since it only acts by imparting chlorine, being incapable, as an aggregate, of entering into combination. 1575. The name of aqua regia, or royal water, was given to this solvent, on account of its property of dissolving gold, the alleged king of metals. Since the promulgation of the French nomenclature, it has been called nitro-muriatic acid; but as this conveys a false idea of its nature, I would call it by its old name, aqua regia, or, if a new name be necessary, I would suggest that of nitrohydrous chlorine. Latterly Gay-Lussac has alleged that iodic acid is a solvent of gold ; and by Mitscherlich, the same power is ascribed to selenic acid. When boiled with three parts of sulphur, and one of potash, one part of gold is dissolved as an ingredient in a solu- ble sulphosalt. (1541.) Of the Compounds of Gold icith Oxygen. 157G. By subjecting a protochloride of gold to a solution of caustic potash, oxide of potassium, the chlorine and oxygen exchange places; so that a protoxide of gold, and chloride of potassium result. The trioxide of gold is obtained by digesting an aqueous solution of the bichloride with magnesia in slight excess. This oxide, which is capable of acting both as an oxacid and as an oxybase, in this instance acting in the former capacity, combines with the magnesia, and constitutes an aurate, of which the greater part precipitates, while the remainder continues in solution. The preci- pitate should be washed with water until it ceases to acquire a yellow colour by the addition of chlorohydric acid. It should then be digested with nitric acid, which combines with the magnesia, and thus isolates the trioxide. If the nitric acid em- ployed, be concentrated, we obtain the trioxide in an anhydrous state, and of a brown colour; but if dilute, as a yellowish-red hydrate. 1577. The protoxide consists of one atom of gold and one of oxygen, the trioxide, of one of gold and three of oxygen. Hence, agreeably to the example of Thenard, I designate it as a frzoxide. (756.) Acting as a base, this oxide combines with nitric or sulphuric acid. It is precipitated from these combinations by water, which acts, probably, in this case, as an oxybase of hydrogen. (826.) 1578. As an oxacid, trioxide of gold unites with all the alkalies and alkaline earths. The aurate of ammonia, a compound which explodes by percussion, has long been known under the name of fulminating gold. Berzelius alleges that there are two kinds; one, containing an excess of ammonia, detonates more powerfully ; the other, formed with a lesser quantity of the alkali, contains chloride of gold, by which its power is enfeebled. 1579. A precipitate, of a beautiful purple colour, may be obtained either by mixing diluted solutions of the chlorides of tin and gold ; or by immersing an ingot of tin, or tin foil, in a solution of chloride of gold, containing some free chlorohydric acid. To this precipitate the name of purple powder of Cassius has been given. I infer from the account of this compound, given by Berzelius, that it consists of gold, tin, 292 INORGANIC CHEMISTRY. hydrogen, and oxygen. Respecting the mode of combination there is some ob- scurity. 1580. In consequence of this property of producing the purple of Cassius, tin, whether in the metallic state or that of dissolved protochloride, is the best test for gold. 1581. Berzelius does not consider the purple powder into which gold is reduced by successive electric discharges, as any thing more than metallic gold in a state of minute division. Of the Compounds of Gold with the Halogen Bodies. 1582. The protochloride of gold is obtained by exposing the trichloride to a gentle heat, which drives off two atoms of chlorine, leaving the gold in combination with the remainder. If the heat be carried too far, it is apt to decompose the protochlo- ride into metallic gold and chlorine. On this account it is better to stop the opera- tion before the trichloride is entirely decomposed, and to wash the resulting mass with water, which removes the trichloride, and leaves the protochloride, which is insoluble in that fluid when cold. A solution of the trichloride of gold is obtained when gold is dissolved in aqua regia, any excess of chlorohydric acid is expelled by heat. It is of a pale yellow colour, and has an astringent and disagreeable taste. This chloride combines as an acid with the chlorides of the alkaline metals, forming chloroaurates. Hence I consider this as entitled to the appellation of chloroauric acid. The trichloride of gold, as its name implies, is composed of one atom of gold, and three atoms of chlorine. 1583. Bromine forms with gold a tribromide, which corresponds in composition and chemical properties with the trichloride of the same metal. The iodide of gold agrees, in composition and chemical relations, with the protochloride of gold. The cyanide of gold appears to act as an acid. Of the Compounds of Gold with Sulphur. 1584. Gold forms with sulphur a protosulphide and a trisulphide. The protosul- phide is formed by passing a current of sulphydric acid gas through a boiling solution of the trichloride. It is of a deep brown colour, and is decomposed by heat into metallic gold and sulphur. The trisulphide may be precipitated by passing a current of sulphydric acid into a dilute solution of the trichloride, or by adding an acid to a solution of the sulphurate of potassium. The trisulphide is of a deep yellow colour, and is decomposed by heat. With sulphobases it acts as an acid, but with the more powerful sulphacids as a base. Experimental Illustrations. 1585. Some gold leaf is placed in two glass vessels. Nitric acid being poured into one, and chlorohydric acid into the other, the gold is not acted upon; but when the contents of the two vessels are united, the gold disap- pears. 1586. Gold, dissolved by aqua regia, and precipitated by sulphate of iron, or by chloride of tin. A cylinder of phosphorus, immersed in a solution of the metal, acquires the appearance of a cylinder of gold. Separation of gold from its solution by ether. Effects of the ethereal solu- tion exhibited. Action of mercury on gold leaf. PLATINUM. 293 SECTION II. OF PLATINUM. 1587. This metal is found in South America, and in Russia, in an im- pure granular form, known as the native grains of platinum. In addition to this metal, the native grains contain several other metallic substances in a state of combination or mixture. The aggregate thus described is, for the most part, soluble in aqua regia; the habitudes of platinum, in this respect, as well as in others, being more analogous to those of gold than any other body in nature. On adding to a solution of the native grains of platinum, in aqua regia, a solution of sal-ammoniac, an orange-yellow precipitates, but little soluble in water, is obtained. This being carefully washed and desic- cated, and finally exposed to a red-heat, in a platina, porcelain, or black lead crucible, the metal is isolated in a mass so porous, as to have received the name of platina sponge, from its resemblance in structure to the well known substance to which this name belongs. By extreme mechanical pressure the platina sponge is so far consolidated that by intense heat and hammering it is welded into a perfectly tenacious mass, having, in a high degree, all the attributes of a noble metal. (1404.) 1588. I have lately been enabled, by an improvement in my hydro-oxy- gen blowpipe, to fuse twenty-five ounces of platinum into a malleable mass. The metal thus obtained, is less liable to flaws than that produced by the welding process above described. My process is especially important as enabling us to unite old platina ware, or clippings, into malleable masses of convenient dimensions, without re-solution in aqua regia. The necessity of taking this last mentioned course, reduce^ platina in that state, to a value not more than higher than that of the native grains. (394.) 1589. According to Berzelius, platinum, as obtained by the process above-mentioned, is alloyed with iridium, and inferior to the pure metal in colour, brilliancy, ductility, and malleability ; while at the same time it is stronger and more suitable for the purposes for which it is usually em- ployed. It may be obtained pure, by precipitating chloroplatinic acid from its aqueous solution by chloride of potassium, igniting the precipitate, redissolving it, and precipitating again by sal-ammoniac; and lastly, by re- ducing the precipitate by ignition to the spongy form, from which by pres- sure and the welding process, it may be made coherent and malleable, as in the abovementioned process for obtaining the metal. 1590. Properties. The colour of this metal, as ordinarily obtained, is intermediate between that of silver and steel; but when pure, as above stated, it resembles silver both in colour and softness, more than when alloyed with iridium. Its specific gravity is 21.53. A cubic inch of it weighs more than three-fourths of a pound. It is nearly twice as heavy as lead, being the heaviest body known. It is less ductile and malleable than gold, but harder and more tenacious; though, in these respects, inferior to iron, Like iron, it is susceptible of being hammered and welded at a white-heat. It can neither be oxidized nor melted by the highest temperatures of the air- furnace, or forge. It was first fused in a focus of the solar rays, afterwards by means of a stream of oxygen gas on ignited charcoal, but much more easily by the compound blowpipe, under which it was first oxidized and dis- sipated by heat. It fuses and burns \-isi]\ in the Voltaic circuit, and is 294 INORGANIC CHEMISTRY. dispersed and oxidized by mechanical electricity. It is one of the worst conductors of heat among metals. 1591. In its habitudes with oxygen, chlorine, and the acids, it is analo- gous to gold, being, like that metal, detected by protochloride of tin, which produces with it a claret colour. It unites so energetically with tin at a red-heat, as to occasion the phenomena of combustion. (348.) When in a divided state, as obtained by igniting the chloroplatinate of ammonium, it amalgamates with mercury by trituration. 1592. Platinum combines with boron, silicon, and phosphorus. On ac- count of its infusibility at the highest temperatures produced by the air-fur- nace, or forge, and its insusceptibility of being corroded by the acids usually employed in chemical processes, it is much used by chemists for crucibles, evaporating vessels, and spoons; also in experiments in which Voltaic series are resorted to as a means of decomposition. I employ it in my galvano- ignition apparatus. (335.) At high temperatures, it is acted upon by the alkaline hydrates, and by almost all metals, especially tin and lead. I had a platinum crucible perforated, by fusing in it some flint glass, which con- sists mainly of lead, silicic acid, and potash. 1593. The equivalent of platinum is 99. Of the Compounds of Platinum with Oxygen. 1594. Platinum forms a protoxide, consisting of one atom of metal and one atom of oxygen, which may be obtained from the chloride, by the addition of potash. It forms also a bioxide, containing two atoms of oxygen to one of metal, as the name implies. The protoxide acts as an oxybase only ; the bioxide, both as an oxybase and oxacid. In the last mentioned capacity it enters into combination with ammo- nia, in the compound called fulminating platinum, and which we may with propriety call platinate of ammonia, or ammonium. Dr. Thomson alleges the existence of some other oxides of platinum. Of the Compounds of Platinum with the Halogen Class, 1595. Of Chloroplatinic Acid. The platinum, in the solution of aqua regia above described, being in the state of a bichloride and acting as an acid agreeably to my fundamental definition, (631,) is capable of combining with other chlorides acting as chlorobases. With either the chloride of potassium, or the chloride of ammonium, (sal ammoniac, 1109,) it forms compounds which are but very sparingly soluble in water. Hence the precipitate resulting from the addition of the last mentioned chlorobase, and the employment of the chloride (or chlorobase) of potassium, in the process recommended by Berzelius. (1589.) But since the bichloride of platinum acts as an acid, it is proper to designate it as a chloroplatinic acid. In this I am supported by the authority of Dr. Thomson. It follows that the pre- cipitates obtained as above described, are severally chloroplatinates of am- monium, and potassium. 1596. The superior solubility of the chloroplatinate of sodium, enables us to distinguish solutions in which this metal exists as the radical, from those in which potassium performs the same part; as with the latter only is orange-coloured precipitate obtained, on adding chloroplatinic acid. 1597. Of Chloroplatinous Acid. This name is given to the protochlo- ride of platinum, as it is, according to Berzelius, capable of combining with the same chlorobases as chloroplatinic acid. Chloroplatinous acid is ob- tained by exposing the bichloride (chloroplatinic acid) to heat. It is alleged to have a grayish colour, and to be insoluble in water. Its compounds with chlorobases must consistent^ be called chloroplatinites. PLATINUM. 295 Experimental Illustrations. 1598. Platinum exhibited in the state of native grains, and in the malleable state. Precipitated from its solution by chloride of ammonium, and chloride of tin. A precipi- tate produced in salts of potash by chloride of platinum, distinguishes them from salts of soda. Combustion of pla- tinum with tinfoil. Of the Nomenclature of Compounds formed with Halogen Bodies, called Double Salts by Berzelius. 1599. In order to present an intelligible view of the discordant names of the salts above described, I will here subjoin a table of the names of some compounds formed with chlorine by platina, of which mention has been made. (1596.) Table of the various Names given to the Double Chlorides, such as those described in the case of Platina. Names according to the old Theory of the Muriates. Potash, } Soda, Muriate of . In chlorine, this metal takes fire spontaneously, forming a protochloride, which, from the butyraceous consistency assumed in melting, received from the old chemists the appellation of the butter of bismuth. This compound may also be ob- tained in the anhydrous state, by heating three parts of the bichloride of mercury with one of bismuth. When anhydrous, the protochloride is white, volatile, and deliquescent: when subjected to water, a white insoluble oxychloride is formed. 1786. A crystalline hydrate of the protochloride of bismuth may be formed by dis- solving bismuth in aqua regia, and evaporating the solution. * Thenard, Traite de Chimie, 6eme ed. ii. 484. 324 INORGANIC CHEMISTRY. 1787. Bromides of bismuth may be obtained by heating bismuth with bromine. Iodides may be produced in like manner. 1788. Fluorine and cyanogen both combine with bismuth. The cyanide, however, is known only in a state of combination. Of the Compounds of Bismuth with Sulphur and Selenium. 1789. Bismuth forms a bisulphide when heated with sulphur. At the moment when the combination takes place,' a great deal of heat is evolved. It is crystalliza- ble, less fusible than bismuth, and possesses the metallic lustre and a grayish-yellow colour. 1790. When selenium is heated with bismuth, a crystalline selenide is formed of a silvery white colour. Experimental Illustrations. 1791. Bismuth and its oxide, exhibited. Its hue and habitudes with the blowpipe, compared with those of zinc, antimony, and arsenic. SECTION IX. OF IRON. 1792. This metal is found abundantly in nature, principally in union with sulphur or oxygen. 1793. Large masses of iron have been . observed to fall to the earth at different times, and in various countries. Besides these metallic masses, a great number of stony bodies, called meteorolites, or aerolites, have fallen in like manner. In the latter, iron always exists both in the state of prot- oxide, and in that of metallic globules. The iron in these globules, and in the masses abovementioned, always contains nickel or cobalt, or both. Native metallic iron has also been found in small quantities, but does not contain nickel or cobalt. Iron is one of the most generally distributed substances in the creation, and, in the state of oxide, probably the most universal colouring matter. 1794. Four species of ferruginous minerals are very abundant in nature; magnetic oxides and sulphides, and sulphides and oxides which are not magnetic. 1795. Since ferruginous minerals, if not magnetic in the first instance, becomes so by exposure to the flame of the blowpipe, the magnet is a most useful test for iron. The ores of iron consist principally of the sesquioxide, or of a compound of this oxide with the protoxide, called the black or mag- netic oxide. The means of extricating iron from its ores, will be mentioned in treating of the compounds of iron with carbon, which will on that ac- count be treated of first. 1796. Properties. The mechanical properties of iron are too well known to need description. It is the most tenacious substance in nature, especially as steel, and the hardest among the malleable metals. In ducti- lity it has a still higher pre-eminence. Few metals are more easily oxidized by the joint agency of air and moisture. In the pulverulent form, in which it is reduced from the sesquioxide by means of hydrogen, iron is liable to become ignited by the access of atmospheric oxygen, even after it has been IRON. 325 completely refrigerated. This result is more likely to ensue, if a little alu- mina has been previously mixed with the oxide ; since this prevents the union of the particles, and thus keeps them in that state of minute division which is favourable to the success of the experiment. Iron is nearly as difficult to fuse as platinum. Its specific gravity is 7.788. 1797. The equivalents of iron, and of its compounds with oxygen, chlo- rine, and sulphur, are as follows : Iron - ...... 28 Protoxide, 1 atom metal, 1 atom oxygen 36 Sesquioxide, or ^ 2 atoms 3 atoms 80 Red oxide, Magnetic or V 3 atoms 4 atoms v Black oxide, l Or 1 atom protoxide and 1 atom sesquioxide } Protochlovide, 1 atom metal, 1 atom chlorine 64 Sesquichloride, 2 atoms 3 atoms 164 Protosulphide, 1 atom ,, 1 atom sulphur 44 Sesquisulphide, 2 atoms 3 atoms 104 Bisulphide, 1 atom 2 atoms 60 Of the Compounds of Iron with Carbon, Boron, Silicon, and Phosphorus. 1798. When ferruginous salts, containing carbon as a constituent, are exposed to heat without access of air, the iron and carbon are left in a state of combination in various proportions. Some of these carburets, that from the oxalate, or from the tanno gallate or Prussian blue, for instance, are liable to take fire when exposed to the air. 1799. The process of evolving iron from its ores, comes under the fourth case of affinity, in which one body in excess, combines with two others previously united. The carbon with which the ore is ignited, combines both with the oxygen and metal, converting the one into a fusible carburet, called cast iron, the other into carbonic acid. The proportion of carbon in cast iron varies from 1 part in 25, to 1 in 15. In commerce, there are four varieties of cast iron; the ichite, the black, the gray, and the mottled. In the white, there is the least carbon, in the black, the most; and probably, in the other kinds, less than in the black, and more than in the white kind. 1800. It should, however, be understood, that cast iron is probably never a pure carburet. Usually, it contains silicon and manganese, and frequently magnesium and phosphorus. This last mentioned element renders the iron less malleable at a high temperature. From cast iron, the malleable metal is extricated by exposure to heat and air; by which carbon, and silicon when present, are oxidized; the one being separated as a silicate of iron with the scoria, the other escaping as carbonic acid. 1801. In some cases, malleable iron is obtained directly from the ore, by means of heat and charcoal. 1802. Pure malleable iron is converted into steel, by being heated in contact with charcoal in ovens without access of air. The process is called cementation. By these means, iron acquires from l-50th to l-120th of its weight of carbon. The bars are blistered by the operation as they are seen in commerce. Broken up and welded, they form shear steel. Fused, they constitute cast steel. 1803. It would appear that silicon is a frequent, if not a necessary ingredient in steel. According to Berzelius, the presence of manganese and phosphorus is essen- tial to the formation of good steel. Damask steel is a peculiar species, which pos. sesses the property of exhibiting waving lines on its surface, when acted on by an acid. It is alleged by Thenard, that some experiments which have recently been made, tend to prove that this is owing to the presence of two carburets of iron ; one of which is blackened by the acid, while the other resists its action. I think it more probable, that the appearance in question is owing to a mixture of iron and steel. It has, however, been ascertained that a peculiar variety of this steel called wootz, which comes from India, contains aluminium, and may be imitated by the introduc- tion, into steel, of a minute portion of that metal. 326 INORGANIC CHEMISTRY. 1804. A silicuret, and probably a boruret of iron, maybe obtained by, heating iron with a mixture of charcoal and silicic or boric acid. 1805. A phosphuret of iron is produced, when phosphate of iron is heated with lampblack. It resembles iron in colour, but is brittle, and fusible by the blowpipe. Of the Compounds of Iron with Oxygen. 1806. Iron forms two oxides, a protoxide and a sesquiox- ide:- the former, consisting of an atom of each constituent; the latter, of two atoms of metal, and three atoms of oxy- gen. Both these oxides act as bases. 1807. The protoxide is formed during the solution of the metal in diluted sulphuric acid. The reaction which ensues under these circumstances, is always attended by the evolution of hydrogen, arising from the decomposition of the water in combination with the acid, the oxidation of the metal, and the formation of a sulphate of the protoxide. 1808. I infer that the atom of water, which, by a union with the anhydrous acid, constitutes the aqueous sulphuric acid of Berzelius, or in other words the acid of the shops of sp. gr. 1.850, acts as an oxybase. So that the result may be ascribed to the exchange of one radical for ano- ther; an atom of iron taking the place of an atom of hy- drogen. Agreeably to this view of the subject, the aqueous acid should be regarded as a sulphate of hydrogen. 1809. The protoxide of iron, forms with sulphuric acid, a green solution, which, by evaporation, yields crystals of the same colour, known in pharmacy as green vitriol, or green sulphate of iron. From a solution of this salt, the protoxide may be precipitated by an alkaline solution in the state of a white hydrate. From this hydrate the water cannot be expelled either by heat or desiccation, without causing the protoxide to acquire oxygen, either from the water in union with it, or from the air. 1810. In consequence of this avidity for oxygen, solu- tions of this oxide become gradually more or less solution3 of the sesquioxide; exchanging their grass green colour for that of red wine. 1811. The protoxide appears to exist in chalybeate springs, and, in its nascent state, to be soluble in water; although I do not find that other chemists are aware of the fact. Its existence in them is ascribed usually to the presence of carbonic acid; but I have observed it in the water of the Yellow Springs, which gave no precipitate with lime-water. IRON. 327 1812. We have only to make a pile of silver coin, alter- nated with disks of sheet iron, in a glass tumbler, supplied with water, in order to impart to the latter the property of chalybeate spring water. In the tumbler, as in those springs, the red oxide will soon be seen precipitating, and tinging, with its appropriate hue, both the liquid and the vessel. 1813. As light promotes the further oxidation and con- sequent precipitation of the iron, the solution of the prot- oxide, by the means which I have described, will be more permanent in an opake vessel. 1814. There does not appear to be any mode in \vhich the protoxide of iron can be isolated. 1815. The sesqnioxide, or peroxide of iron, also called the red oxide from its colour, which is of a dingy blood-red, exists in nature in great abundance, forming, sometimes, large beds or masses, at other times, botryoidal, or mam- millary concretions. 1816. Ochres consist of alumina, mixed with the sesqui- oxide of iron, either uncombined with water, or in the state of hydrate. 1817. The sesquioxide, as we have already stated, is spontaneously produced by the absorption of oxygen by the protoxide, when exposed to the air. In fact, by the addition of nitric acid to any ferruginous solution, the iron becomes more or less sesquioxidized. On the other hand, it may be partially deoxidized, and restored to the state of protoxide, by digestion with iron filings, or by the addition of protochloride of tin. Hence, the black colour of the tanno gallate of iron, which, when suspended in water, constitutes common writing ink, is removed by the addi- tion of this protochloride. It appears probable, that the tin passes to the state of oxychloride in the following way. One portion of this metal takes chlorine from another por- tion to form a bichloride, while the other portion abstracts oxygen from the iron, forming of course an oxide. The resulting oxide combining with the bichloride, an oxychlo- ride is produced. In the state of protoxide, to which the iron is brought by the partial deprivation of oxygen, it forms a colourless compound with the tanno gallic acid.* * Protochloride of tin is the most efficient remedy for removing ink stains, or iron mould. It is made by the reaction of chlorohydric acid with an excess of tin in powder or in tinfoil, or otherwise sufficiently comminuted. It is better to use it 328 INORGANIC CHEMISTRY. 1818. When a solution of the protoxide of iron is added to a solution of the chloride of gold, this metal probably relinquishes its chlorine to one portion of the iron in the protoxide. The oxygen, consequently displaced, sesqui- oxidizes another portion of the iron ; so that metallic gold precipitates, and the chloride and oxide of iron, combining in the state of an oxychloride, remain in solution. 1819. By intense heat the acid may be expelled either from a nitrate or sulphate of iron, and the sesquioxide consequently obtained. It has been stated, in treating of sulphuric acid, that it was originally distilled from copperas or green vitriol, the sulphate of the protoxide of iron. The oxide which remains after the expulsion of the acid, has long been known under the name of colcothar of vitriol. The metal necessarily becomes peroxidized during this process by the partial decomposition of the acid. (771.) To ren- render it free from all remains of acid, it should be washed with water. 1820. The protoxide and sesquioxide of iron combine in various proportions. The scales, called finery cinder, which fly off during the forging of incandescent iron, con- sist of protoxide and sesquioxide. The oxide formed by subjecting iron at a red-heat to steam, is the black oxide, composed of one atom of protoxide and one of sesquioxide. 1821. The native magnetic oxide of the mineralogists, is, according to Thenard, the same as that obtained when iron is oxidized by steam. 1822. The same author alleges that neither the hydrate of the protoxide nor sesquioxide are magnetic ; this quality being exhibited only when the two oxides are associated in the proportion of one atom of protoxide to one of ses- quioxide. Of the Reaction of Iron with Acids. 1823. The reaction of iron with sulphuric acid when hot and concentrated, is quite analogous to that already de- scribed as taking place between that acid, and mercury, copper, lead, &c. The reaction of iron with this acid with an equal portion of acetic acid, and the addition of its volume of water. The spot to be operated upon should be first moistened with water, to prevent the chlo- ride from spreading unnecessarily. After the stain disappears, the remains of the solution should be well washed, as-otherwise corrosion might ensue. IRON. 329 when dilute, has been mentioned and explained above. (1807.) 1824. In its habitudes with nitric acid, iron resembles tin and bismuth. If the acid employed be concentrated, and the iron minutely divided, the reaction is liable to be- come explosive. 1825. With gallic and tannic acids, as existing in the infusion of galls, the sesquioxide of iron produces a purple or black colour, in other words, ink.* With succinic acid the sesquioxide yields a brown precipitate; with benzoic acid, an olive coloured precipitate; and with meconic and sulphocyanhydric acid, a blood-red colour. Of the Compounds of Iron with the Halogen Class. 1826. Chlorine forms with iron a protochloride and sesquichloride, which correspond in composition with the oxides. 1827. The anhydrous protochloride may be obtained by passing chlorohydric acid gas over iron filings heated to redness in a glass tube. 1828. The hydrous protochloride may be procured by the action of liquid chlorohydric acid on iron filings. The protochloride, in its anhydrous state, is of a pale green colour, astringent, crystallizable, very soluble in water, and volatilizable by heat. When exposed to the action of the air, it absorbs oxygen, and forms an oxychloride, consist- ing of the sesquioxide, and sesquichloride. 1829. The hydrous sesquichloride of iron is produced, * The materials for common writing ink are an infusion of galls, sometimes with the addition of a small proportion of an infusion of logwood, and green sulphate of iron, which, in its ordinary state, contains more or less of the sesquioxide of that metal. The black hue of the liquid resulting from these infusions, increases in in- tensity by exposure to the atmospheric oxygen, and consequent increase of the pro- portion of sesquioxide. Dr. Ure conceives that ink made of iron, in an inferior de- gree of oxidizement, penetrates the paper better than that which is made by solutions of the sesquioxide, and finally becomes equally black upon paper. There is some obscurity respecting the composition of this liquid on account of the discordancy of opinion which has existed respecting the acids of which it consists. It may be inferred that the acid prevailing in a fresh infusion of galls, is mainly that which \v;is formerly called tannin, and latterly tannic acid. This acid is gradu- ally converted into gallic acid, when the infusion in which it exists is exposed to the air. Either acid will produce ink, with ferruginous solutions, but it does not appear to me, that it is known which of the two answers the best for this purpose. I have found a beautiful blue black ink to result from the reaction of a filtered in- fusion of galls in cold water with finery cinder. It is too much prone to precipitate, but by agitation is always resuspended. The old practice of introducing cotton into an inkstand, removes this inconvenience in great measure. Over common ink it has these advantages, it contains no free sulphuric acid, and makes no grounds which cannot be resuspended. 42 330 INORGANIC CHEMISTRY. when the sesquioxide of iron is exposed to the action of chlorohydric acid. It may be obtained in the anhydrous state, by heating iron filings in an excess of chlorine. Thus obtained, it is volatile and deliquescent. 1830. Bromine and iodine form compounds with iron, which no doubt correspond in composition with its oxides and chlorides. 1831. There are two fluorides of iron which act either as acids or bases. 1832. The protocyanide of iron is formed by exposing the cyanoferrite of ammo- nium, which is a compound of the cyanides of iron and ammonium, to heat in a re- tort. The cyanide of ammonium, which is volatile, passes over, leaving the proto- cyanide of iron in the form of a grayish-yellow powder. This cyanide acts as a powerful cyanacid, combining in that capacity with the cyanides of almost all the metals. It also combines with cyanhydric acid, but whether as an acid or a base, appears to me doubtful. I incline to the opinion that it acts as an acid, forming a cyanoferrite of the cyanobase of hydrogen. 1833. The sesquicyanide of iron is obtained by mingling a solution of the fluosili- cate of the fluobase of iron with a solution of the cyanoferrite of potassium. A fluo- silicate of the fluobase of potassium precipitates, and the sesquicyanide of iron re- mains dissolved. Its solution is of a deep brownish-yellow colour, and an astringent taste. If we attempt to obtain it in the solid form by desiccation, it is partially decomposed, and converted into Prussian blue. 1834. Of Prussian Blue. When the cyanide of potassium is mingled in solution with a ferruginous salt, a precipitate ensues, well known under the name of Prussian blue, having been first accidentally discovered at Berlin. It would seem, that to perfect the colour of this precipitate, both oxides of iron should be present; so that the protoxide may produce the protocyanide, and the sesquioxide the sesquicyanide. These cyanides, by their union, form the compound in question. (1299, &c.) Of the Compounds of Iron with Sulphur and Selenium. 1835. Iron forms with sulphur a protosulphide, a sesquisulphide, and a bisulphide. Moreover, the protosulphide combines in various proportions with the bisulphide or with the metal. 1836. Hydrated protosulphide is alleged to be formed during the combustion which arises from triturating with moisture two parts of iron filings with one and a half of sulphur. This hydrated protosulphide is liable to absorb oxygen with a rapidity so great as to produce ignition. Owing to this property, its presence in bituminous coal beds sometimes causes them to take fire spontaneously. 1837. Native protosulphide of iron is of rare occurrence ; but the magnetic and bisulphides are abundantly found in nature, especially the latter, which is one of the most common minerals. From its resemblance to gold, it is frequently mistaken for that metal by inexperienced observers. When intensely heated, a portion of its sul- phur sublimes; and hence it is one of the sources of that important substance. 1838. Of the I/sulphide, it is alleged by Thenard, that there are two varieties, which, though identical in composition, are dissimilar in their crystalline form and in their properties. Of these varieties, only one is susceptible of spontaneous reac- tion with air and moisture, and consequent conversion into a sulphate. To a similar transformation of this and other sulphides, we are indebted for the greater part of the green vitriol, or sulphate of iron, used in the arts. Beds of t.besc~minerals, in a state of decomposition, are to be met with in every country. 1839. Sesfjuisiilpkide of iron is produced, when the sesquioxide of this metal is exposed to a current of sulphydric acid, provided the temperature be not above 212. At a higher temperature, a bisulphide results. 1840. The protosulphide and bisulphide of iron, constitute, as Thenard mentions, the mineral called magnetic pyrites. This mineral is also formed, as he alleges, when iron in a state of intense ignition is presented to sulphur, and when either the ses- quisulphide or bisulphide is fused. In fnct, it would seem that he considers none of the other sulphides as magnetic ; although the presence of a greater proportion of iron in the protosulphide \voulii lead us to suspect in it a greater susceptibility of magnetic influence. Berzelius, however, considers the protosulphide as magnetic. 1841. The selenide of iron is formed by causing the vapour of selenium to pass over iron filings heated in a glass tube. It has a metallic brilliancy, and a deep gray colour approaching to yellow. ZINC. 331 Experimental Illustrations. 1842. Iron, dissolved by chlorohydric and sulphuric acid. Red and magnetic oxide of iron, exhibited; and their solutions precipitated by galls, and by cyanoferrite of potassium. Effects of protochloride of tin on the colour of the precipitates. Ores of iron, rendered magnetic by the blowpipe. SECTION X. OF ZINC. 1843. This metal exists in nature in four states; in that of sulphate, sili- cate, carbonate, and sulphide. As a silicate or carbonate, it is known in mineralogy under the name of calamine ; its sulphide is called blende. 1 844. From calamine or from blende, when converted into an oxide by roasting, the metal is obtained by heating it with charcoal, in a crucible with a hole in the centre of the bottom. To this a sheet iron tube is adapted by which the zinc is conveyed in liquid globules or vapour to a vessel of water situated beneath, within which the vapour consequently condenses. This process is called distillation by descent, " distillatio per descensum." Zinc may be purified by redistillation. 1845. Properties. -Zinc is of a brilliant metallic white colour, tinged with the hue of lead. Its structure is strikingly crystalline. Its specific gravity is about 6.86. Under ordinary circumstances it is not malleable, but may be laminated by rollers at a heat somewhat above that of boiling water. It melts at about 680. That it may be volatilized at a higher tem- perature must be evident from the process by which it is obtained as above- mentioned. (1844.) By exposure to the atmosphere it is slightly oxidized, but at a white heat burns rapidly with intense light, the resulting oxide be- ing volatilized in fumes. Water is rapidly decomposed when passed in the state of steam over ignited zinc, or when presented to it together with a due proportion of sulphuric or chlorohydric acid. Zinc combines with carbon and phosphorus. 1846. The equivalents of zinc, and of its compounds with oxygen, chlo- rine, and sulphur, are as follows : Zinc, ....... 32 Protoxide, 1 atom metal, 1 oxygen, 40 Peroxide, doubtful. Chloride, 1 1 chlorine, 68 Sulphide, 1 1 sulphur, 48 Of the Compounds of Zinc with Oxygen. 1847. The protoxide of zinc is formed during the com- bustion of the metal in atmospheric air. From the light- 332 INORGANIC CHEMISTRY. ness and fleeciness of its texture, when obtained in this way, it was formerly variously called pompholix, nihil album, or lana philosophica. The protoxide may be ob- tained from one variety of the ore called calamine, by heating it to expel carbonic acid. To prepare it as it is presented to us in the shops, the ore is roasted, pulverized, and levigated. A better process, as I conceive, is that of collecting the woolly matter produced by the combustion of the metal. But to either of these modes I should prefer that of precipitating the oxide from the sulphate in solu- tion, by liquid ammonia. 1848. Peroxide of zinc has been obtained by mingling bioxide of hydrogen with a dilute solution of the nitrate of this metal, as in the process for the peroxide of copper, which it resembles in many of its properties. (1706.) The protoxide usually acts as a base, though in some- cases it may act feebly as an acid. The peroxide performs the part neither of a base nor of an acid. 1849. The reaction of sulphuric acid with zinc is similar to that of the same acid with iron. (1807.) When subjected to nitric acid, zinc takes all the oxygen from one portion of the acid, while the protoxide thus formed is dissolved by another portion; meanwhile the nitrogen escapes with violent effervescence. Professor Emmet has recommended the reaction of this metal with the nitric acid in nitrate of ammonia, as the means of procuring pure nitrogen. 1850. If the solution of the acetate of zinc, obtained by the reciprocal decomposition of the acetate of lead and sulphate of zinc, (522,) be clarified by subsidence or filtra- tion, and then evaporated, the acetate of zinc may be ob- tained in the crystalline form. It will also be in a state of purity if the materials have been used in the equivalent proportions, or with a slight excess of the acetate of lead. Pure acetate of zinc may also be obtained by the process for forming the arbor Saturni; as in that process, after a sufficient time, the lead is completely precipitated by the zinc, which remains in solution. In this process a piece of zinc being suspended in a solution of acetate, or, prefera- bly, nitrate of lead, and having a greater affinity for oxy- gen, it deoxidizes the lead. This, being thus rendered insoluble, precipitates; while the resulting oxide of zinc is seized by the acid and dissolved. ZINC. 333 1851. The acetate of zinc is also obtained, agreeably to one of the formulas of the Pharmacopoeias, as a tinc- ture, in other words, in alcoholic solution, by subjecting a mixture of sulphate of zinc and acetate of potash, in equi- valent proportions, to alcohol. The mixture of the salts is followed by a reciprocal decomposition, analogous to that produced by the mixture of sulphate of zinc, and ace- tate of lead; excepting that the resulting sulphate of lead is quite insoluble in water, and separates by precipitation; while, in the other case, both of the resulting salts, being more or less soluble in water, alcohol is employed to sepa- rate them. This liquid does not dissolve the sulphate of potash, while it readily takes up the acetate of zinc. Of the Compounds of Zinc with the Halogen Class. 1 852. Anhydrous chloride of zinc is formed during the combustion of zinc in chlorine. It was formerly called the butter of zinc, from its con- sistency. It is of a grayish-white colour, translucid, astringent, fusible at the temperature of boiling water, and volatilizable at a red-heat. By dis- solving zinc filings in chlorohydric acid, and evaporating the solution to dryness, we may obtain this chloride in the state of hydrate. 1853. Zinc combines with iodine, fluorine, and cyanogen. The cyanide acts as an acid, the fluoride both as a base and an acid. Of the Compounds of Zinc loith Sulphur and Selenium. 1854. Sulphide of zinc may be obtained by heating the sulphate to whiteness with a carbonaceous paste. It is difficult to combine zinc directly with sulphur; but when the vapour of sulphur is passed over incandescent zinc, a combination takes place with a violent commotion, and the evolution of so much heat as to volatilize part of the zinc. The same result ensues when zinc filings are suddenly and in- tensely heated with the persulphide of potassium, or the powdered bisulphide of mercury. r w .V>. Sulphide of zinc is solid, yellow, tasteless, less fusible than zinc, indecom- posable by heat alone, but reducible by intense ignition with charcoal. It is a power- ful sulphobase. I >.">i'. When the sulphate of zinc is decomposed at a low red-heat by hydrogen, an oxysulphide, or in other words a compound of the sulphide and oxide, is formed. l-'7. When the vapour of selenium is passed over zinc heated to redness, the union of the two substances takes place with violence, being attended with the phe- nomena of active combustion. The resulting selenide is a yellow powder. Experimental Illustrations. 1858. Zinc, subjected to diluted sulphuric, and diluted chlorohydric acid. Arbor Saturni, produced by it in a so- lution of nitrate of lead. Combustion of the metal in an incandescent crucible. Its habitudes with the blowpipe, 334 INORGANIC CHEMISTRY. exhibited. Reaction of zinc filings and bisulphide of mer- cury; also of the melted metal with a fused nitrate. e < SECTION XL OF ARSENIC. 1859. This metal is found in nature, in combination with oxygen, sulphur, and various metals. It is sold in commerce under the name of cobalt, and in the state in which it bears this name, it is full of crevices, and so much tarnished or blackened by oxidizement, both internally and externally, that it is not possible, even by a fresh fracture, to see the true colour and lustre of the metal. 1860. In order to attain this object, the cobalt (as it is absurdly named) should be coarsely pulverized, and intro- duced into a glass tube sealed at one end. The tube should be less than half full. Thus prepared, it should be placed within a cylinder of iron, closed at the base. The butt-end of a gun barrel will answer. The space between the iron and the glass should be filled with sand, and another gun barrel applied, so as to receive any fumes which may arise, and conduct them into a chimney. That portion of the glass tube which contains the arsenic, should be kept red-hot for about half an hour. After the appara- tus is quite cool, the metal will be found in crystals of great splendour, occupying that portion of the glass tube which is next the part heated to redness. 1861. Properties. Exposed before the blowpipe, arsenic is distinguished by burning before it fuses, and by emitting copious white fumes, which have the odour of garlic. These fumes are easily produced, by projecting a portion of the metal upon a hot iron, or by subjecting it in any other way to heat and air. They are evolved on a large scale during some metallurgic operations, and, after being purified by a subsequent sublimation, constitute the ar- senious acid or white arsenic of the shops. This metal is extremely brittle and friable, and, when newly sublimed, has the colour and brilliancy of polished steel. It requires less heat to vaporize than to fuse it; so that it cannot be melted without the aid of a pressure greater than that of ARSENIC. 335 the atmosphere. Thenard alleges that it may be sublimed in a retort filled with nitrogen, at the temperature of 356. I am under the impression, that the nitrogen must co- operate as a solvent in this result ; taking up the metal in the warmer part of the retort, and depositing it in the colder part. 1 have ascertained that metallic arsenic, situated in a glass tube immersed in melted lead, is not volatilized, unless so far as it may be oxidized ; and, more- over, in the process for obtaining the arsenical ring, I have remarked that it is formed just beyond the part of the tube which is reddened by the heat. 1862. The following table gives the equivalents of arsenic, and of its compounds with oxygen, chlorine, and sulphur. Arsenic, 38 Suboxide, doubtful. Arsenious acid, 2 atoms metal, 3 atoms oxygen, 100 Arsenic acid, 2 atoms 5 atoms 116 Protochloride, 1 atom 1 atom chlorine, 74 Sesquichloride, 2 atoms 3 atoms 184 Protosulphide, 1 atom 1 atom sulphur, 54 Sesquisulphide, 2 atoms 3 atoms 124 Persulphide, 2 atoms 5 atoms 156 Of the Compounds of Arsenic with Oxygen. 1863. According to Berzelius, the black matter which obscures the brilliancy of metallic arsenic on exposure to the air, is a suboxide. Thenard seems inclined to con- sider it as a protoxide; while by other chemists it is treat- ed as a mixture of arsenious acid and the metal ; as, when exposed to heat or to acids, it yields arsenious acid, and metallic arsenic. But as it appears that arsenious acid is a compound of oxygen and the metal, in the ratio of three atoms of the former to two of the latter, it would be rea- sonable to infer the existence of a compound consisting of an atom of each. Besides, it has been ascertained by Berzelius, that the exposure of arsenic to air never causes an absorption of more than eight per cent, of oxygen; whereas, to form arsenious acid, the metal must absorb thirty-two per cent. Now it seems very improbable that, under the same circumstances, one portion of the metal 336 INORGANIC CHEMISTRY. should absorb thirty-two per cent, of oxygen, while ano- ther portion should absorb none. 1864. Arsenious acid is found in nature both in crystal- line form and in that of white powder. It forms the fumes which are so copiously evolved when arsenic is ignited in the air. It is milk-white, has a rough and slightly acid taste, followed by a flavour feebly sweet. It is hardly necessary to state that it is a virulent poison. When subjected in open vessels to a low red-heat, it softens, and sublimes, in the form of a white powder, or, when the ves- sels are large and the operation slow, in regular octohe- dral crystals. 1865. Arsenious acid is soluble in water, but not to any great extent. Berzelius states that a saturated solution of it in boiling water, in which the deposition of crystals has commenced, contains but a twelfth or thirteenth of its weight. There is much uncertainty, and some mystery, respecting the extent of its solubility in cold water. Ber- zelius quotes an observation made by Fischer, that the portion employed is never entirely dissolved; and that as the ratio of the water to the acid increases, this being al- ways in excess, the quantity dissolved lessens. Thus 80 parts of the former take up-^Vth of its weight; 160 parts, -rioth; 240 parts, ^th; and 1000 parts, only ^Voth. 1866. Arsenious acid, when subjected in close vessels to a heat approaching to redness, fuses into a transparent glass of the specific gravity of 3.699, unchangeable in dry air, but gradually becoming white and opake in a humid atmosphere. In the last mentioned state, it appears to be more soluble in boiling water, and to be retained in solu- tion to a greater extent than in the transparent state. The transparent acid reddens litmus ; while, by the opake, litmus previously reddened may be restored to its original colour. These varieties of arsenious acid are, therefore, considered as isomeric. (1153.) 1867. Of Arsenic acid. By digestion in aqua regia or in strong nitric acid, evaporation of the resulting solution to dryness, and subsequent ignition nearly to redness in a platinum crucible, arsenious acid acquires two additional atoms of oxygen ; so that a compound is formed in which the metal is to the oxygen, in the proportion of two atoms to five. This compound is arsenic acid, which is solid, white, and caustic, and capable of reddening litmus. ARSENIC. 337 When exposed to heat it melts into a glass ; but if the heat be pushed to redness, it is decomposed into arsenious acid and oxygen gas. This is a more powerful acid, a more virulent poison, and more energetic in its affinities, than arsenious acid. Like other acids, which bear a high temperature without decomposition or volatilization, it expels, when aided by heat, the volatile acids from their combinations. It forms, with certain metallic oxides, salts which crystallize in the same form as the corresponding phosphates; whence, as I have elsewhere stated, (474,) arsenic and phosphoric acid are said to be isomorphous. Of such bodies, one may be substituted for the other in crystalline compounds, without altering the form of the resulting crystals. 1868. Arsenic acid is deliquescent, and much more so- luble than arsenious acid ; yet after being vitrified by heat, it does not dissolve completely at first, but deposites a white powder, which, by frequent stirring, finally dissolves. In consequence of this and some other differences in their properties, it has been supposed that the melted and un- melted arsenic acids are isomeric with regard to each other. 1869. Arsenious and arsenic acid severally combine with the metallic oxides. Arseniate of potash is formed, when arsenious acid or metallic arsenic is deflagrated with nitrate of potash. Fowler's solution, the liquor potasses, ar- senitis of the U. S. Pharmacopoeia, is made by boiling ar- senious acid and carbonate of potash, of each 64 grains, with a pint of distilled water, and adding four fluidrachms of the spirit of lavender. The arsenious acid, displacing the carbonic acid, forms with the alkali an arsenite of pot- ash. This solution produces a yellow precipitate with ni- trate of silver, without the aid of ammonia, as the place of this base is supplied by the potash. 1870. The soluble arsenites and arseniates yield preci- pitates with solutions of copper and silver, and destroy the blue colour of the iodide of starch, by the superior affinity of iodine for arsenic. In the instance of copper and sil- ver, an arsenite or arseniate of those metals is formed. The arsenite of copper is of an apple-green colour, and forms a pigment called Scheele's green. The arsenite of silver is yellow ; the arseniate, brick-red. 1871. Sulphuric acid when cold does not react with ar- 43 338 INORGANIC CHEMISTRY. senic; but when warm, the acid is decomposed, and arse- nious acid formed. 1872. Of nitric acid the reaction with arsenic is similar to the reaction of sulphuric acid with the same metal ; ex- cept that it takes place without the aid of heat, and that the arsenious acid which is at first produced, is finally con- verted into arsenic acid. i Of the Compounds of Arsenic with the Halogen Class. 1873. A sesquichloride of arsenic is obtained by the direct reaction of chlorine with arsenic, or by the distillation of this metal with the .bichloride of mercury. If, in this process, the protochloride of mercury be substituted for the other, a protochloride of arsenic is generated : and by the reaction of the metal with an excess of chlorine, a perchloride results. 1874. The sesquichloride is a colourless, fuming liquid, of an oleaginous consistency, quite analogous, both as to the means of evolution and its pro- perties, to the bichloride of tin, or fuming liquor of Libavius. (1766.) 1875. Bromine and iodine severally form compounds with arsenic, which correspond in composition with the sesquichloride. 1876. The fluoride of arsenic is a colourless, fuming liquid, which pro- bably consists of two atoms of arsenic, and three of fluorine. Of the Compounds of Arsenic with Sulphur and Selenium. 1877. There is scarcely any limit to the number of proportions in which arsenic and sulphur appear to be capable of combining; yet Berzelius ad- mits the existence of but five distinct sulphides, and Thenard recognises only three, a protosulphide, a sesquisulphide, and a persulphide. By the union of these with various quantities of the metal, or of sulphur, all the other compounds are supposed to be produced. 1878. The proto, sesqui, and persulphide severally combine with sulpho- bases, as sulphacids. 1879. The protosulphide of arsenic^ known in commerce by the name of realgar , may be obtained by heating a mixture of two parts of sulphur, and rather less than three and a half parts of arsenic. It is procured in the large way by distilling arsenious acid with sulphur. It is tasteless, crystallizable, less fusible than arsenic, and of an orange-red colour. When heated in close vessels it volatilizes unchanged, but if the air be ad- mitted it is converted into arsenious and sulphurous acid. It is found native. 1880. The sesquisulphide is obtained by adding chlorohydric acid to a mixed solution of sulphide of potassium and arsenite of potash. The oxy- gen of the arsenious acid and of the potash unites with the hydrogen of the chlorohydric acid, the chlorine with the potassium, and the sulphur with the arsenic. The chloride of potassium remains in solution, while the arsenic and sulphur precipitate in the state of sesquisulphide, and in the form of beautiful yellow flocks. 1881. The sesquisulphide is found in nature, and is known in commerce under the name of orpiment. It is crystallizable. When heated gently in close vessels it melts, and if the heat be further elevated, volatilizes, and may be condensed unchanged. If the access of air be permitted during the operation, sulphurous and arsenious acid are formed. 1882. The persulphide of arsenic is formed by passing sulphydric acid ARSENIC. 339 gas through a solution of arsenic acid in water. It is yellow, and resem- bles orpiment. It is fusible, volatilizable, and capable of reddening litmus. 1883. A selenide is produced, when arsenic is dropped into selenium, previously liquefied by heat. If this selenide be subjected to distillation at a red-heat, a perselenide is obtained. Of the Compounds of Arsenic with Phosphorus and Hydrogen. 1884. A phosphuret of arsenic may be formed by heating phosphorus with the metal. It is black and brilliant. 1885. Of arseniuretted hydrogen. If in charging the self- regulating reservoir for the evolution of hydrogen, (797, &c.) an aqueous solution of arsenious acid be substituted for water, the other materials being as usual sulphuric acid and zinc, arseniuretted hydrogen will be evolved with no less facility, than that with which the evolution of the pure gas is accomplished, when the arsenious acid is not present. 1886. When this gas is made to pass through a tube kept by means of a lamp or a coal fire, as hot as the glass will bear, the arsenic is precipi- tated in the metallic form, in the cooler part of the tube, just beyond the heated part. 1887. The process above described, is decidedly preferable to any other, not only as respects convenience and economy, but the safety of the ope- rator. 1888. To procure this gas devoid of pure hydrogen, Soubieran recom- mends that an alloy of equal weights of arsenic with zinc be made by fusion, and subjected to strong chlorohydric acid. 1889. If confidence is to be placed in the recommendation of the distin- guished chemist above named, it follows, that by the introduction of such an alloy into the self-regulating reservoir, substituting strong chlorohydric for diluted sulphuric acid, there would be a supply of pure arseniuretted hydrogen at command. 1890. Arseniuretted hydrogen is highly inflammable, in common with all other aeriform compounds of hydrogen. It is extremely deleterious to life, being injurious when liberated in quantities too small to be immediately annoying to the operator. It is productive of nausea and vomiting, some- times of constipation, sometimes of purging. As palliatives of these symp- toms, Berzelius recommends warm tea, and sulphydric acid gas. 1891. In generating this gas for illustration, by the apparatus employed for the philosophical candle, (805,) I inadvertently inhaled enough to pro- duce a transient indisposition. Gehlen, a respectable German chemist, lost his life by a similar inadvertency. This gas is the more insidious, since we are not warned of its presence by the fetidity of its odour, as in the case of the combinations of hydrogen with sulphur and phosphorus, and other substances. A ten-thousandth part of this gas may be detected in a gaseous mixture, by the metallic pellicle which it causes upon a solution of corrosive sublimate. 1892. Oil of turpentine appears to form a crystalline compound, by re- acting with arseniuretted hydrogen. 1893. A solid compound of arsenic with hydrogen has been made, by subjecting an alloy of potassium and arsenic to water ; and likewise by the decomposition of water by the Voltaic series, one of the wires, employed for the purpose, terminating in a piece of arsenic immersed in that liquid. 340 INORGANIC CHEMISTRY. Experimental Illustrations. 1894. Appearance and habitudes of arsenic, in its me- tallic and crystalline form, contrasted with those of zinc, antimony, and bismuth. Arsenious acid and its solutions, exhibited; also, Fowler's solution, or solution of arsenite of potash. Arsenious and arsenic acid, in solution, added to large vessels of clear water, and detected by sulphy- dric acid, or by ammoniacal nitrate of silver or copper. Same acids precipitated by lime-water. Exhibition of Scheele's green, or arsenite of copper. Combustion of arseniuretted hydrogen, displayed. Of the Means of detecting Arsenic, in Cases where poisoning by Arsenical Compounds is suspected. 1895. As respects arsenic, the most important object of attention is the means of detecting this metal, in cases in which an arsenical compound may be used as a poison. 1896. The first steps are of course directed to the col- lection and preservation of all the matter which may have come from the patient in vomiting, or which may be ob- tained by opening the stomach. As the combination of this metallic poison usually administered is arsenious acid in the pulverulent form, all the matter collected and the surface of the stomach should be rigidly examined, in order to detect any particles which may remain in that state. Berzelius counsels us especially to scrutinize those spots in the stomach which appear to have been inflamed, in order to ascertain whether any particles of the poison are lodged in them. 1897. In the next place, the whole mass, collected and preserved as above advised, should be thrown into water, which, while stirred to cause the suspension in it of the lighter portions of the matter, should be poured off, to- gether with that lighter matter from the heavier subsiding portion. The liquid thus separated should be filtered; and both the resulting filtered solution, and the heavier matter which may have sunk to the bottom of the vessel, should be evaporated to dry ness in an appropriate oven, or in a vessel kept hot by boiling water. The whole being quite ARSENIC. 341 dry, it should be introduced into a glass or porcelain ves- sel ; and, adding a sufficient quantity of strong nitric acid to cover the mass, it should be subjected to a heat adequate to cause a brisk reaction. This should, if necessary, be sustained by further additions of the acid, until there is no longer any organic matter undecomposed. 1898. As nitric acid can have no other effect upon ar- senic than that of converting it into arsenic acid, in which state it is less volatile than in any other; this process tends at the same time to annihilate the organic impurities, and to secure the metal. Thus the matter to be assayed is much diminished in bulk, and if it contain arsenic must hold it as arsenic acid, which is more soluble than arseni- ous acid. Hence, if the dry mass be digested with water, a solution will be obtained, which, being filtered, may be precipitated by lime-water. The arseniate of lime which precipitates, being dried, should be mingled with about one-fourth of its weight of powdered charcoal, and intro- duced into a 'glass tube, sealed at one end. The mixture having been made to settle down to the sealed end within as narrow limits as possible, a little cotton wick must be fastened to the end of a wire, by twisting the wire so as to form one end into an eye, and passing the wick through the eye, and winding it about the end of the wire, until a plug of cotton be made just large enough to slide in the tube like a piston. For greater security, the wick may be wound about the wire, so that one end may be held in the hand. By means of the piston, thus formed, the portion of the tube, not occupied by the mixture, may be wiped clean. The tube should now be subjected to the flame of a spirit lamp, the piston being retained in it, as near the mixture as it can be without being injured by the heat. The heat should be applied at first to the anterior part of the mass, proceeding to the posterior part afterwards ; and as soon as the whole ceases to give out aqueous vapour, the piston should be passed quickly down, so as to wipe away the moisture condensed, together with any accom- panying foulness. The piston being again beyond the reach of the heat, the part of the tube containing the mix- ture should, by the aid of a blowpipe, be exposed to a tem- perature as high as the glass will bear. If there be arsenic in the mixture, it will now appear in a bright metallic ring, just beyond that part of the tube which was heated red- 342 INORGANIC CHEMISTRY. hot. On cutting the tube at the part where the ring ap- pears, and heating it by a spirit lamp, the alliaceous smell of arsenic will be perceived, if this metal be present; and the same smell will be experienced on igniting the cotton of the piston above mentioned. 1899. The process thus described for obtaining the ar- senical ring is nearly the same as that which I employed in the analysis of some matter sent to me from Westches- ter by Dr. Thomas; having been obtained from the sto- mach of a woman poisoned by her husband. I afterwards repeated it successfully at Westchester, in presence of Dr. Thomas and another physician ; and upon their evi- dence of the result so obtained, the murderer was con- victed. Before his execution he confessed himself to be guilty. 1900. Where no arsenic can be detected in the contents of the stomach, it may be found in the membranes, or coats. Hence, in making the examination for arsenic, the stomach should be boiled in nitric acid, until all the organic matter is destroyed. 1901. Very minute quantities of arsenic may be detected by the aid of silver or copper in solution. With silver, arsenic acid gives a brick-red, arsenious acid, a yellow precipitate. With copper, arsenious acid produces a very striking green precipitate of arsenite of copper, called Scheele's green. Sulphydric acid gas produces, with either acid, a yellow precipitate of sulphide of arsenic. As these results are precarious, and liable to be produced by other causes, they should not be considered as conclu- sive evidence. 1902. In the case of the murder above mentioned, I found that the arsenic acid, as procured from the contents of the stomach, would not assume the appropriate hue in precipitating with silver, whether before or after its union with lime. Instead of a brick-red, it was of a muddy colour. By Dr. Feutchwanger, who was present during many of my experiments, this was ascribed, correctly, as I believe, to phosphoric acid. It has been stated, that it is difficult to separate these acids when associated, from their isomorphism, or, in other words, crystallizing in the same form. (474.) 1903. By simple affinity, neither arsenious nor arsenic acid can be precipitated by the soluble salts of silver or ARSENIC. 343 copper. Hence an alkali must be present, either in union with the arsenical acids, or with the metallic salt. This object is attained conveniently, by the addition of ammonia to the nitrate of silver or copper; as, with either of those metals, that alkali forms a soluble ammoniacal nitrate. (524). 1904. A great improvement in our means of detecting arsenic has been introduced by Marsh, of London. It has been mentioned, (1885,) that if in the process for evolving hydrogen by a self-regulating reservoir, an aqueous solu- tion of arsenious acid be substituted for pure water, the materials and manipulation being otherwise the same, in lieu of pure hydrogen, arseniuretted hydrogen will be ge- nerated. From the observations of the ingenious mecha- nician above named, it appears, that if any mixture con- taining arsenic be added to water and acid, used in an analogous miniature apparatus, the nascent hydrogen will combine with the arsenic, however minute the proportion. Consequently, a jet of the gas when inflamed, by its hue, fume, and odour, and still more when allowed to play upon the surface of a piece of porcelain or glass, will demon- strate the presence of arsenic. In this last mentioned case, a dark stain will be made, consisting of concentric circles, of which that which is central will have the metallic hue of the arsenical ring, especially when examined through the glass. 1905. The great objection to this process, as it came from the hands of Marsh is, that when the proportion of arsenic is very small, the whole may escape before the operator may be enabled to detect it. Hence, it w r ould seem preferable to resort to the expedient recommended by .Soubieran, of passing it through a tube heated by a lamp (1886); or to pass all the gas generated through some liquid competent to effect a complete absorption of the arsenic. For this purpose a solution of corrosive sub- limate might answer. (1891.) Experimental Illustrations. 1906. Small portions of arsenious acid, or of the ar- seniate of lime, mingled with powdered charcoal, and sub- jected to heat in a glass tube. Arsenical ring, produced and exhibited. 344 INORGANIC CHEMISTRY. 1907. Self-regulating reservoir of hydrogen, charged with an aqueous solution of arsenious acid, sulphuric acid, and zinc. (796, &c.) Deposition produced by the flame upon glass, mica, or porcelain. Gas passed through a glass tube, reddened by a lamp, or gas flame, deposits me- tallic arsenic in a film resembling in appearance the ar- senical ring. SECTION XII. OF ANTIMONY. 1908. Antimony sometimes occurs in nature in the metallic state and in that of oxide, also abundantly as a sulphide. It is in fact to the sulphide that the name of antimony is given in commerce, the metal being designated as the regulus of antimony. 1909. The ores of this metal had been known for a long time; but for its extraction from them, the world is indebted to Basil Valentine, who lived towards the close of the fifteenth century. Since that period, from its utility in medicine, it has been eminently an object of investigation. 1910. Metallic antimony may be obtained by mingling the sulphide with two-thirds of its weight of bitartrate of potash, and one-third of its weight of nitre, and deflagrating the mixture in a red-hot crucible. The oxygen of the nitre converts the sulphur into sulphurous acid, which escapes ; while the alkali of both the salts operates as a flux, or in other words promotes the fusion of the mass. The carbon of the tartaric acid counteracts the oxidizement of the metal. 1911. Charcoal, intimately intermingled with carbonate of potash or soda, may be used instead of the bitartrate. 1912. Antimony thus obtained is not quite pure. To render it so it may be dissolved in aqua regia, precipitated in the state of oxychloride by water, and revived by ignition with bitartrate of potash. 1913. Properties. Antimony is so brittle as to be easily pulverized. It displays a crystalline structure, and may be crystallized by the process resorted to in the case of sulphur. (750.) When quite pure and newly fractured, it is of a silver-white colour, and very brilliant. If it be rubbed between the fingers, they acquire a perceptible odour. Its specific gravity is 6.7. It fuses a little below a red-heat. When thrown in a state of fusion upon a board, it produces a beautiful effect, being dispersed into a multitude of ignited globules, which emit copious fumes of oxide, and leave their traces upon the board. The temperature of the globules seems to be supported by their own combustion. 1914. A single globule of the metal, being brought to a state of ignition by the blowpipe flame upon a piece of charcoal, if held, after operation of the blowpipe is discontinued, in a current of air, such as exists usually at an aperture in a flue, will, in consequence of the heat arising from its union with the atmospheric oxygen, continue at a bright red-heat until nearly consumed. 1915. According to Berzelius, the purity of antimony is indicated by a ANTIMONY. 345 silvery whiteness, and a granular or fine lamellar texture; whereas the metal otherwise does not excel tin in whiteness, and is coarsely lamellar, almost as if susceptible of cleavage. It appears to me, that the differences here re- ferred to, are dependent, as in other cases, on slowness or quickness of cool- ing. A button which was granular when taken from a crucible refrigerated in water, by fusion in an iron mortar in which it was prevented from cool- ing quickly by proximity to a fire, acquired a lamellar texture. Bad anti- mony looks like hornblende rock when broken, as to its crystalline texture, and cannot be fused into a globule as liquid or pure. It will not answer as well for the experiment of throwing on the board, as the pure metal. 1916. The equivalents of antimony, and of its compounds with oxygen, chlorine, and sulphur, are as follows : Antimony, ........ . 64 Sesquioxide, 2 atoms metal, 3 oxygen, 152 Antimonious acid, 2 4 160 Antimonic acid, 2 5 168 Sesquichloride, 2 ,,3 chlorine, 236 Bichloride, 2 ,,4 272 Perchloride, 2 5 - 308 Sesquisulphide, 2 ,,3 sulphur, 176 Bisulphide, 2 ,,4 192 Persulphide, 2 ,,5 208 Of the Sesquioxide of Antimony. 1917. Sesquioxide of antimony may be obtained by ex- posing the metal to heat with access of air; by moderately roasting the sulphide; or by subjecting the sesquichloride to water, in which case a powder precipitates, called powder of Algaroth, from the name of the physician who first recommended it to public attention. This powder, being an oxychloride, by digestion with the carbonate of potash, is converted into the sesquioxide. It may also be obtained by the reaction of the metal with diluted nitric acid, afterwards repeatedly digesting the resulting subsalt in water, until this liquid no longer reddens litmus. In the form in which the sesquioxide is obtained by heat and air, it received formerly the name of argentine flowers of antimony. When obtained from the oxychloride, the ses- quioxide has a tinge of gray. If the sesquioxide, as pro- cured by the last mentioned method, be heated, it takes fire, and is converted into antimonious acid. 1918. Sulphuric acid, when cold or diluted, does not re- act with antimony, but, when warm and concentrated, is partially decomposed, evolving sulphurous acid, and form- ing a sesquioxide of the metal, with which the undecom- posed acid combines. By water the acid may be for the 44 346 INORGANIC CHEMISTRY. most part removed from this sulphate, so as to cause in it an excess of oxide so great as to render it competent for the production of tartar emetic, by digestion with the bi- tartrate of potash. In this case, the excess of oxide in the sulphate, and the excess of acid in the bitartrate, unite, converting the latter salt into the double tartrate of pot- ash and antimony, or tartar emetic. 1919. The sesquioxide acts feebly both as an acid and a base. Combined with bitartrate of potash, it constitutes tartar emetic, and is the only compound of antimony with oxygen, which is considered as medicinal.* 1920. Tartar emetic may be considered as consisting of Two equivalents of tartaric acid, 66 x 2 = 132 One of sesquioxide of antimony, 152 One of potash, 48 Two of water, 9x2= 18 350 Of the Compounds of Antimony with Oxygen, of inferior importance medicinally. 1921. Antimonious acid is generated" by digesting antimony in nitric acid, evaporating the liquid to dryness, and calcining the residue; or by thoroughly roasting the sulphide of antimony with access of air. Antimo- nious acid is white, tasteless, infusible, fixed, indecomposable by heat, and insoluble in water. 1922. When nitric acid is added to a solution of the antimonite of potash, the antimonious acid is precipitated in the state of hydrate. In this state it reddens litmus paper. 1923. Anhydrous antimonic acid is obtained by subjecting the oxychlo- ride to the action of nitric acid, and afterwards exposing the resulting mass to a temperature of 500 or 600, to expel any excess of this acid. By de- flagrating the metal with four times its weight of nitre, dissolving in water the resulting mass, and afterwards adding nitric acid, which combines with the alkali, hydrous antimonic acid is also procured. 1924. Anhydrous antimonic acid is yellow, tasteless, and insoluble in water. When hydrous, it is white, and has the property of reddening litmus. 1925. Just at the moment when certain antimonites and antimoniates, subjected to a low red-heat, lose their water of crystallization, they give rise to a transient light, as vivid as would result from a true combustion. Yet * In the last edition of this work, I quoted, on the subject of tartar emetic, an article previously published by Dr. Bache, in the American Cyclopedia of Practical Medicine. This article I shall not introduce into this edition, because the informa- tion which it comprises, has been given in the United States' Dispensatory, which we owe to my friend abovementioned, and to my colleague, Dr. Wood. I presume that of this Dispensatory, every matriculant of our university will be provided with a copy, as it appears to rne to be of itself equivalent to a choice library of useful medical knowledge. ANTIMONY. 347 they incur in consequence no change in weight. Their colour is rendered brighter, and they become less susceptible of decomposition by acids. This result ensues especially with the antimoniates of copper, cobalt, and zinc. 1926. The reaction of diluted nitric acid with antimony, is quite analo- gous to that already described in the case of bismuth. According to Ber- zelius, a subnitrate results, which may be decomposed by water as already stated, and converted into a hydrated sesquioxide. But Thcnard informs us that, if this metal be subjected to nitric acid, it is converted into hydrous antimonious acid (acide antimonieux b!anc et hydrate). Possibly the dif- ference may arise from the acid being in one case concentrated, in the other dilute. Of the Compounds of Antimony with the Halogen Class. 1927. Sesquichloride of antimony may be obtained, as Thenard alleges, by distilling the metal with the bichloride of mercury ; also by the reaction of aqua regia with metallic antimony, and subsequent distillation of the resulting liquid, collecting the product in a fresh receiver when it becomes oleaginous in its consistency. He recommends as preferable, however, the action of chlorohydric acid on the sesquisulphide with heat, allowing the sulphydric acid gas to escape into the fire. sThe resulting liquid is to be decanted, and concentrated by heat in a retort, until it acquires an oleaginous consistency. 1928. The sesquichloride has been designated as the butter of antimony. It is white, semitransparent, very caustic, fusible below a boiling heat, and crystallizable in tetrahedrons by refrigeration. It is volatile at a heat be- low redness, and deliquescent, so as to be liquefied by exposure to air. It has already been mentioned, that by subjecting this chloride to copious affusions of water, (eight times its weight, according to Thenard) an oxy- chloride results, formerly called the powder of Algaroth. 1929. Bichloride of antimony, agreeably to the last mentioned author, exists only in combination with chlorohydric acid. 1930. Per chloride of antimony is formed by the combustion of the metal in chlorine. It is a yellow liquid, sending forth thick fumes into the air, with a strong and disagreeable smell. It attracts moisture, and is, in con- sequence, at first converted into a white crystalline mass, but afterwards liquefied by a further accession of humidity. Yet by exposure to a large quantity of water with heat, it is decomposed, and deposits hydrous anti- monic acid. This process is recommended as the best for obtaining this compound. Of the Compounds of Antimony with Sulphur and Selenium. 1931. It has been stated that antimony is procured principally from the native sesquisulphide, which is found in the shops under the name of anti- mony, the metal being distinguished as the regulus. 1932. Sesquisulphide of antimony may be formed from its ingredients, by heating the metal in a state of division with sulphur. It is more fusible than metallic antimony, is crystalline in texture, has a metallic lustre, and a bluish-gray colour. It may act either as a sulphacid, or as a sulphobase. With the sulphides of the alkalifiable metals it forms compounds which may be designated as hyposulphantimonites. 1933. The sesquisulphide and sesquioxide of antimony enter into com- bination with each other in different proportions, forming compounds which 348 INORGANIC CHEMISTRY. must be called oxysulphides, consistently with the nomenclature adopted in the case of the analogous compounds of oxides with chlorides. 1934. When the sesquisulphide of antimony is roasted, in other words exposed to heat with access of air, it becomes more or less oxidized, ac- cording to the duration of the exposure, the degree of heat, and the supply of air. If, after the roasting has continued for some time, the temperature be raised so as to fuse the mass, a vitreous compound will result, the com- position of which will vary according to the ratio of the oxide to the sul- phide, at the time of effecting the fusion. According to Thomson, when the ratio of the former to the latter is as five to one, the compound has the name of crocus of antimony; when the ratio is as three to one, it has been called liver of antimony. 'This name, however, is given by Berzelius to a compound of the sulphides of antimony, with the sulphide of potas- sium or sulphide of sodium. 1935. If the sulphide of antimony, instead of being poured out as soon as it is melted, be kept for a great length of time in a state of fusion in an earthen crucible, it derives a portion of oxide of iron and silicic acid from the crucible, and thus forms a transparent mass of a yellow-hyacinth co- lour, commonly called the glass of antimony. This glass, according to Thenard, is a mixture of oxysulphide of antimony, with the silicates of an- timony and iron. 1936. By the reaction of the sesquisulphide of antimony with the alka- lies, either caustic or carbonated, and either in the wet or dry way, a com- plicated reaction ensues, by which the antimony of the sulphide is more or less oxidized, the metal of the alkali more or less sulphurized; while the residual sulphide of antimony, acting as a sulphacid, combines more or less with the resulting sulphobase of the alkalifiable metal. 1937. The extent to which the sesquisulphide, in the resulting sulpho- salt, can be retained by the sulphobase in an aqueous solution, appears de- pendent upon temperature. Hence, whether the sulphosalt be produced in the dry way and dissolved in hot water, or be generated by boiling the in- gredients in this liquid, the sesquisulphide precipitates by refrigeration. 1938. The precipitate thus obtained, under the name of kermes mineral, was so much in vogue in France, about a century ago, as to induce the go- vernment of that country to purchase from a surgeon of the name of La Ligerie, the art of preparing it. 1939. Thenard alleges that it appears from the analysis of Henry, Jr., that the composition of kermes varies according to the process employed for its production. When prepared by boiling the sesquisulphide in a solu- tion of carbonate of potash or soda, kermes may be considered as a hy- drated oxysulphide ; but when procured by boiling the sesquisulphide in a solution of caustic potash or soda, or by fusion with them or their carbon- ates, and subsequent solution in hot water, it is a hydrated sesquisulphide, containing very little if any oxide. As obtained by precipitation from tartar emetic by sulphydric acid, it is a pure hydrated sesquisulphide. After the kermes has precipitated, a portion of the sesquisulphida still remains in union with the sulphobase. Hence, on the addition of an acid, a further precipitation takes place, both of the sesquisulphide of antimony, and the sulphur of the sulphobase; and these, either by combination or mixture, constitute the golden sulphur of antimony, another well known pharma- ceutical preparation. 1940. According to the analysis of Henry, Jr., as quoted by Thenard, ANTIMONY. 349 the composition of kermes, when obtained in the wet way by carbonate of soda, is as follows : Sesquisulphide of antimony, 62.5 Sesquioxide of antimony, - - - 27.4 Water, 10 Soda, ..... a trace. 1941. Upon the whole it is inferred that the sesquisulphide, in precipi- tating by refrigeration as abovementioned, combines with water in all cases ; and that when the process is conducted in the wet way by means of a car- bonated alkaline solution, the precipitating hydrated sesquisulphide combines with the sesquioxide, forming an oxysulphide. The presence of carbonic acid in union with the alkali is requisite, in order to enable the menstruum to form and dissolve while hot, a double carbonate of the alkali and sesqui- oxide. The latter, being thus taken up by the aid of heat, subsequently, in consequence of the refrigeration and its affinity for the hydrated ses- quisulphide, precipitates in combination with this sulphide, as already men- tioned. 1942. The officinal preparation, called precipitated sulphuret of antimony, is obtained by adding diluted sulphuric acid to a solution of the sesquisul- phide of antimony in a hot solution of caustic potash. A precipitate re- sults which may be considered as a mixture of kermes mineral and golden sulphur of antimony. 1943. Bisulphide of antimony is obtained, according to Thomson, by dissolving antimonious acid in chlorohydric acid, and subjecting the result- ing liquid to sulphydric acid. I infer that four atoms of chlorohydric acid, acting on two atoms of antimony, in union with four atoms of oxygen, will be productive of a bichloride, and that this will be converted into a bisulphide by reaction with the sulphydric acid. 1944. The bisulphide, being resolvable into the sesquisulphide and sul- phur by heat, cannot be produced by the fusion of its constituents. It is of an orange-red colour, and acts as a sulphacid. 1945. Per sulphide of antimony is obtained by passing sulphydric acid through a diluted solution of the pe'rchloride of this metal, to which tartaric acid has previously been added. Its colour resembles that of the bisulphide, though somewhat paler. 1946. The selenide of antimony is obtained by heating this metal with selenium. Like the sulphide, it is capable of entering into combination with the oxide. Experimental Illustrations. 1947. Antimony and its sulphide, exhibited, and exposed to the blowpipe: also, the crystals and solution of tartar emetic. Kermes mineral, golden sulphur, and precipitated sulphuret of antimony, exhibited. Antimony, subjected to acids. Kermes mineral, precipitated from a solution of tartar emetic by sulphydric acid. 350 INORGANIC CHEMISTRY. SECTION XIII. OF METALS PROPER OF MINOR IMPORTANCE. OF PALLADIUM. 1948. Besides iron, copper, and lead, four metals, palladium, rhodium, iridium, and osmium, are found in union with, or accompanying the native grains of platinum, as imported from South America. Accordingly, if a portion of that assemblage of metallic particles, of which the native grains of platinum above mentioned form the principal part, be digested in aqua regia, the platinum, together with the palladium, rhodium, copper, and lead, will be dissolved ; while a black powder will be left, consisting of osmium and iridium in combination with each other. 1949. The platinum having been precipitated from this solution (1587) by the chloride of ammonium, any palladium which it may contain, with all of the other noble metals which may be present, may be precipitated by a bright plate of zinc. The resulting precipitate, after being digested with chlorohydric acid and washed with water, should be redissolved in aqua regia. Any excess of acid should be neutralized by carbonate of soda. From the neutralized solution the palladium may be thrown down by a solution of bicy- anide of mercury which yields its cyanogen to the palladium. An insolu- ble cyanide of palladium, being thus formed, precipitates. By the aid of heat this precipitate is decomposed, the cyanogen is expelled, and the metal is isolated. 1950. Mr. Cloud, of the United States' mint, found this metal in a native alloy of gold which was brought- from Brazil. 1951. The colour of palladium appears to me to have a minute degree of tendency towards the rosy hue of bismuth, not being quite so pale as platinum, which it otherwise much resembles in appearance. It is however more fusible, rather harder, and more elastic. Its specific gravity, also, is much less, being about 11.5. It is malleable and ductile, and insusceptible of oxidizement by heat and air. OF RHODIUM. 1952. After the palladium has been precipitated, the solution contains the chloracids of rhodium, mercury, and several other metals, united with the chloride (or chlorobase) of sodium, resulting from the carbonate of soda, employed as abovementioned to neutralize the excess of acid. There is likewise present a portion of the undecomposed bicyanide of mer- cury. Under these circumstances, chlorohydric acid must be added, in order to convert this bycyanide into a bichloride, and the solution after- wards must be evaporated to dryness. The resulting mass should then be washed with alcohol, which dissolves all the chlorosalts of sodium present, except the chlorhodiate. Rhodium is obtained from this by heating it in a current of hydrogen, which removes the chlorine combined with the metal- the chloride of sodium being removed by water. 1953. Rhodium, according to Berzelius, cannot be fused, except by sub jecting it, when in the state of a sulphide or arseniuret, to an intense heat. After fusion, it resembles platinum in appearance. Its salts are generally either red or yellow. It is named from its chloride, which is rose-red. IRIDIUM. OSMIUM. NICKEL. 351 OF IRIDIUM. 1954. When the black powder, consisting of the osmiuret of iridium, which remains as above stated, after we have subjected the crude grains of platinum to aqua regia, is heated with soda, an osmiate of soda is formed, which may be removed by dissolving it in water. The remaining mass is to be treated with aqua regia, in which the iridium, converted into a chlo- ride, dissolves. By repeating this process, the whole is finally converted into solutions of chloride of iridium, and of osmiate of soda. 1955. From the former, crystals of the chloride of iridium may be ob- tained by evaporation, which, on exposure to a strong heat, yield metallic iridium. 1956. Iridium resembles platinum in appearance, and is probably, ac- cording to Thomson, the heaviest of the metals. When heated in con- tact with air nearly to redness it is oxidized, but on the application of a higher temperature it is again restored to the metallic state. Thenard, how- ever, states, that iridium which has been subjected to a strong heat, is abso- lutely insusceptible of oxidizement by the air at any temperature. 1957. Iridium is said to be the most refractory of the metals, having never been fused until it was placed between the poles of Children's large galvanic battery. It was then converted into a globule, possessing metallic whiteness and lustre. OF OSMIUM. 1958. Osmic acid may be obtained by distilling the solution of osmiate of soda, procured as above described, with nitric acid at a gentle heat. The osmic acid passes over, and may afterwards be reduced by the addi- of chlorohydric acid and mercury. It is, however, alloyed with mercury, and mingled with the chloride of this metal. These may be sublimed by a gentle heat, leaving pure metallic osmium. 1959. Osmium obtained in this way, is of a grayish-black colour; but if a portion of the volatilized oxide be made to pass with a current of hydro- gen through a glass tube, the osmium- is deposited in the form of a ring of metallic brilliancy, and of a white colour. It is so difficult to fuse in close vessels, and so liable to be volatilized when heated in the air, that it has only been obtained in powder, or in minute friable masses. Its volatility in the air arises from its great susceptibility of oxidizement, and the vola- tility of its oxide, the fumes of which are pungent. OF NICKEL. 1960. A mineral had been known to the German miners by the name of kupfer nickel, or false copper. About the middle of the last century, Cronstedt alleged the existence, in this mineral, of a peculiar metal. Never- theless, the metal, thus indicated, was considered by many chemists as an alloy of copper with iron. About 1775, Bergmann confirmed, by an analysis, the allegation of Cronstedt. 1961. Kupfer nickel is principally an arseniuret of nickel, but contains, also, sulphur, iron, cobalt, and copper. Nickel is extricated from it by a tedious and intricate process. 1962. Nickel is of a white colour, difficult of fusion, malleable and not easi- ly oxidized by the air. It is so susceptible of the magnetic influence that a permanent magnet may be made of it. If sufficiently abundant, nickel would be very valuable in the arts. A white alloy of this metal with cop- 352 INORGANIC CHEMISTRY. per, had long been known in China, under the name of packfong. Of late this alloy has been brought into use in Europe, under the name of argen- tane or German silver. It serves for pencil cases and many analogous uses nearly as well as ^ silver. It combines with oxygen, chlorine, iodine, cyanogen, sulphur, and the metals. Its oxides are soluble in the acids, and in their habitudes are much like those of copper. The solubility of its protoxide in caustic ammonia, is an important means of separating nickel from its alloys. OF CADMIUM. 1963. This metal has been derived only from the ores of zinc. During the reduction of calamine, a substance sublimes which yields from 12 to 20 per cent, of cadmium. 1964. A solution of the ore in sulphuric acid, being impregnated with sulphydric acid, the cadmium precipitates in the state of sulphide, mixed with a little sulphide of zinc, and sometimes with sulphide of copper. When these sulphides are exposed to chlorohydric acid, the sulphur unites with the hydrogen of the acid and escapes, and they are converted into chlorides. Carbonate of ammonia being added to the resulting solution of cadmium and zinc, a carbonate of cadmium is alone precipitated. From this, the metal may be obtained by means of heat and charcoal. 1965. Cadmium is almost as white as tin, is without odour or taste, very brilliant, and susceptible of a fine polish. It is crystallizable, mallea- ble, and ductile, and so soft as to yield easily to a file or knife. Its specific gravity is 8.6 nearly. It is too scarce to be usefully applied. It fuses and volatilizes at a very low temperature. OF CHROMIUM. 1966. This metal is found in nature only in the state of an acid and of an oxide, generally united with lead or iron, though in some instances pure. It was in the native chromate of lead, found usually in crystals which rival the ruby in colour, that this metal was discovered by Vauquelin. A com- pound of the sesquioxides of chromium and iron, called incorrectly chro- mate of iron, is found plentifully in this country. The sesquioxide of chro- mium, when intensely heated with charcoal, is reduced, but not without great difficulty. 1967. The presence of chromium in a mineral may be detected by the fusion of a minute portion before the blowpipe with borax, or preferably, with the ammoniacal phosphate of soda. In thi way, a globule of a beauti- ful emerald green results, which preserves its colour either in the oxidizing, or reducing flame. By these characteristics it may be distinguished from copper or uranium; since uranium communicates a green hue only in the reducing flame, copper only in the oxidizing flame. 1968. Chromium is a hard, brittle metal, of a grayish- white colour, and very difficult to fuse. Its specific gravity is 5.9. Its equivalent is 28. It forms with oxygen a sesquioxide and an acid. The compound, heretofore considered as a deutoxide, proves to be a mixture of sesquioxide and chro- mic acid. 1969. The sesquioxide of chromium is easily obtained by exposing the chromate of mercury to heat, by which the mercurial oxide and a portion of the oxygen of the acid are expelled, while the sesquioxide remains in the form of a grass-green powder. It may also be obtained in the state of hydrate, by mixing solutions of the bichromate of potash, and persulphide CHROMIUM. 353 of potassium. This sesquioxide is of a beautiful green colour, which it communicates to some of its compounds, being in fact the colouring matter of the emerald. It appears to act both as an acid and a base. 1970. In common with zirconia and oxide of titanium, the sesquioxide of chromium, when obtained from the hydrate by expelling the water by a gentle heat, becomes incandescent at a certain elevation of temperature, in a way which is altogether unaccountable. At the same time it loses its property of solubility in acids which it before possessed. 1971. Chromic acid may be procured by the following process: Let four parts of the chromate of lead be mixed with three parts of fluoride of calcium, both finely pulverized. Then let five parts of sulphuric acid, de- prived of water as far as possible by boiling, be added, and let the whole be distilled in a leaded or platinum alembic at a gentle heat. A red gas will be developed, producing in the air yellow fumes. This red gas is a fluoride of chromium, which, on being passed into water, is converted into fluohydric and chromic acids. The former may be expelled by evapora- tion, the chromic acid remaining in a state of purity. 1972. If, instead of causing the gaseous fluoride of chromium to enter water, it be conducted by means of a tube into a receptacle of platinum, closed with moistened paper, and having a small quantity of water at the bottom, the gas will be decomposed by the aqueous vapour, mingled with the air of the vessel, and will deposite first about the mouth of the tube, and afterwards throughout the vessel, a flocky vegetation, consisting of ruby- red crystals of chromic acid. 1973. Chromic acid is solid, soluble in water, and capable of reddening litmus. It is decomposed by heat, and by most substances which possess an affinity for oxygen. It possesses an acid and astringent taste, and a ruby-red colour, which it communicates to some of its compounds, as al- ready noticed in the case of native chromate of lead. It forms striking and beautiful precipitates with various metals. That which it produces with lead, is of a splendid orange-yellow, and is much used as a pigment. The colour of the streak left by the red crystals above described, when rubbed upon a hard surface, is likewise orange-yellow ; and the same change en- sues from pulverization. The bichromate of potash is poisonous, and no doubt the acid and its compounds are generally poisons. Chromic acid creates a stain upon the skin which cannot be removed by water, unless it contain an alkali. Where there is any abrasion of the cuticle, the presence of this acid will induce a painful ulcer. Hence the sores to which dyers are exposed who employ bichromate of potash as a dye-stuff. These sores have been alleged to arise even from exposure to the vapours or fumes of this acid. When received into the stomach, chromic acid is a virulent poison. Dr. Ducatel informs us of the case of a labourer who died in five hours, after drawing into his mouth from a syphon, a solution of bichromate of potash ; although he was under the impression that, by spitting, he had avoided taking it into his stomach. 1974. Dr. Ducatel suggests an alkaline solution as the best antidote for this poisonous salt ; as he ascribes its activity mainly to the excess of acid. An instance of a criminal prosecution for poisoning by this bichromate, is men- tioned, which failed from that ignorance of its deleterious properties which Dr. Ducatel's communication must tend to correct.* * See Journal of the Philadelphia College of Pharmacy, for January, 1834, page 272, vol. 5. 45 354 INORGANIC CHEMISTRY. OF COBALT. 1975. This metal is found in nature, principally in union with arsenic* By the exposure of the mineral, thus containing it, to heat, with access of air, the arsenic is oxidized and expelled, and the cobalt is reduced to the state of an impure oxide, called zaffre. By fusion with the alkali and sand, zaffre yields a beautiful blue glass, which, when pulverized, forms the blue vitreous powder called smalt. 1976. Cobalt may be obtained from its oxide, by intense ignition with charcoal, or by subjecting it, while ignited in a porcelain tube, to a current of hydrogen. 1977. Cobalt is brittle, of a grayish-white colour, and feeble lustre. Its specific gravity is 8.5 nearly. It requires a high temperature for its fusion. OF COLUMB1UM. 1978. A metal discovered by Hatchett, in 1801, in a mineral obtained from America, received the name of columbium. It was afterwards detected by Ekeberg in two Swedish minerals, called tantalite and yttrotantalite ; and being supposed to be a new metal, was called tantalum. Wollaston afterwards demonstrated the identity of tantalum with columbium. 1979. This metal is found in the state of an acid, combined either with manganese and a little iron, or with yttria. Both combinations are very rare. It may be reduced by heating the fluocolumbate of potassium, or fluoride of columbium and potassium, with potassium. 1980. Columbium is a brittle metal, of an iron-gray colour, having the metallic lustre. It is infusible by the most intense heat of the forge fire. OF MANGANESE. 1981. Manganese exists in nature principally in the state of a black bioxide; rarely in that of phosphate, sometimes in the state of sulphide. The utility of this oxide, as a source of oxygen gas, as an ingredient in glass, and as one of the agents for evolving chlorine, has been noticed. (663.) The metal is obtained by heating the oxide intensely with charcoal or potassium. It is gray, brittle, hard, and scarcely fusible by the highest heat of the forge, or air furnace. In the metallic state, it has not been applied to any useful purpose. 1982. Manganese is remarkable for the number of compounds which it forms with oxygen. Besides a protoxide, sesquioxide, and bioxide, it forms two acids, the manganic, and oxymanganic or permanganic acids. The salts of the latter detonate with combustibles. 1983. When the black oxide (bioxide) is fused with nitrate of potash, a compound results, of which the aqueous solution becomes blue, violet, and red, and finally colourless, Hence this compound has been called chame- leon mineral. These colours appear to be produced by the conversion of the manganate of potash, into an oxymanganate. OF MOLYBDENUM. 1984. This metal is only found in the state of sulphide, resembling plum- bago, or united with oxygen and lead in the state of molybdate of lead. From the sulphide it is obtained by ebullition with nitric acid, which acidifies both the sulphur and metal. The sulphuric acid being expelled by heat, the molybdic acid is decomposed by intense ignition with charcoal. TITANIUM. TUNGSTEN. URANIUM. CERIUM, &C. 355 1985. As from the difficulty of fusing it, molybdenum has been only obtained in small grains, its properties are but little known. It is alleged to have a high degree of metallic lustre, and a white colour. OF TITANIUM. 1986. Titanium, like many other metals, is only interesting as an item in the knowledge which human skill and assiduity have accumulated, with respect to the materials of the globe which we inhabit. It is obtained by separating the oxide from the substances with which it is naturally mixed, and heating it intensely with charcoal. 1987. Titanium was first ascertained to exist in the state of oxide, by Mr. Gregor, in a mineral called menachanite. It was subsequently detected in the metallic state by Dr, Wollaston, in minute cubic crystals, in the slag found at the bottom of a smelting furnace. 1988. These crystals were conductors of electricity, of the specific gra- vity of 5.3, and hard enough to scratch rock crystal. In colour and lustre, they were like burnished copper. They resisted the action of nitric acid and aqua regia, but were oxidized by being heated with nitre. OF TUNGSTEN. 1989. In 1781, Scheele, having analysed a stone known by the name of tungsten, or heavy stone, concluded that it consisted of an acid united with lime. Bergmann suspected the radical of this acid to be metallic. Messrs. D'Elhuyart verified his conjecture, by heating tungstic acid intensely with charcoal. 1990. Tungsten is grayish-white, brilliant, and extremely difficult to fuse. Its specific gravity is 17. 6- OF URANIUM. 1991. Uranium is a rare production in nature, and has scarcely been found in sufficient quantities for an adequate observation of its properties. It is stated to have the metallic lustre, a reddish-brown colour, to be crys- talline in its structure, and scarcely susceptible of fusion by the heat of a forge fire. OF CERIUM. 1992. Cerium, according to Vauquelin, who was unable to obtain it in masses larger than the head of a common pin, is a white brittle metal. From some experiments made by Children and Thomson, it appears to be susceptible of volatilization. OF VANADIUM. 1993. Vanadium was discovered, in 1801, by Del Rio, in a lead ore from Zimapan, in Mexico ; but Collet Descotils, to whom the mineral was sent, having made some new experiments upon it, pronounced it to be an ore of chromium. Del Rio himself having acquiesced in this opinion, it was generally adopted until 1830, when Sefstrom discovered this metal again in a variety of Swedish iron, and in the scoria of the forge at which the iron had been wrought. 1994. Vanadium resembles molybdenum in appearance; and in its pro- perties lies between that metal and chromium. 356 INORGANIC CHEMISTRY. Experimental Illustrations. 1995. Exhibition of various specimens of the metals mentioned in the preceding pages. Magnetic influence of nickel, demonstrated. Solutions of silver, mercury, and lead, precipitated by chromate of potash. Sesquioxide of chromium, evolved by heating the chromate of mercury. Exhibition of the fluoride of chromium. Effects of co- balt, also of manganese, upon vitrified borax. SALTS. 1996. In my preliminary exposition of the grounds of the classification and nomenclature adopted in this work, I alleged the word salt to be insus- ceptible of any definition consistent with the use made of it by Berzelius as a basis of nomenclature. As the reader, who has studied this work so far, as to have reached this page in due course, should have acquired a know- ledge of the facts upon which the above cited allegation was founded, I will here quote the language in which those facts were stated, and my inferences from them justified. 1997. The most striking feature in the nomenclature of Berzelius, is the formation of two classes of bodies; one class called " halogene" or salt producing, because they are conceived to produce salts directly ; the other called " amphigene," or both producing, being productive both of acids and bases, and of course indirectly of salts. To render this division eligible, it appears to me that the terms acid, base, and salt, should, in the first place, be strictly defined. Unfortunately there are no terms in use, more broad, vague, and unsettled in their meaning. Agreeably to the common accepta- tion, chloride of sodium is pre-eminently entitled to be called a salt ; since in common parlance, when no distinguishing term is annexed, salt is the name of that chloride. This is quite reasonable, as it is well known that the genus was named after this compound. Other substances, having in their obvious qualities some analogy with chloride of sodium, were, at an early period, readily admitted to be species of the same genus; as, for in- stance, Glauber's salt, Epsom salt, sal ammoniac. Yet founding their pre- tensions upon similitude in obvious qualities, few of the substances called salts, in the broader sense of the name, could have been admitted into the class. Insoluble chlorides have evidently, on the score of properties, as little claim to be considered as salts, as insoluble oxides. Luna cornea, plumbum corneum, butter of antimony, and the fuming liquor of Libavius, are the appellations given respectively to chlorides of silver, lead, antimony, and tin, which are quite as deficient of the saline character as the corre- sponding compounds of the same metal with oxygen. Fluoride of calcium (fluor spar) is as unlike a salt as lime, the oxide of the same metal. No saline quality can be perceived in the soluble " haloid salts," so called by Berzelius, while free from water ; and when a compound of this kind is SALTS. 357 moistened, even by contact with the tongue, it may be considered as a salt formed of an hydracid and an oxybase, produced by a union of the hydro- gen of the water with the halogene element, and of the oxygen with the radical. It is admitted by Berzelius, vol. 3, page 330, that it cannot be demonstrated that the elements of the water, and those of an haloid salt, dissolved in that liquid, do not exist in the state of an hydracid and an oxy- base, forming a salt by their obvious union. 1998. On the other hand, if, instead of qualities, we resort to composi- tion as the criterion of a salt ; if, as in some of the most respectable che- mical treatises, we assume that the word salt is to be employed only to de- signate compounds consisting of a base united with an acid, we exclude from the class chloride of sodium, and all other " haloid salts," and thus overset the basis of the distinction between " halogene" and " amphigene" elements. 1999. Moreover, while thus excluding from the class of salts, substances which the mass of mankind will still consider as belonging to it, we assem- ble under one name combinations opposite in their properties, and destitute of the qualities usually deemed indispensable to the class. Thus under the definition that every compound of an acid and a base, is a salt, we must attach this name to marble, gypsum, felspar, glass, and porcelain, in com- rrlon with Epsom salt, Glauber's salt, vitriolated tartar, pearlash, &c. But admitting that these objections are not sufficient to demonstrate the absurdity of defining a salt, as a compound of an acid and a base, of what use could such a definition be, when, as I have premised, it is quite uncertain what is an acid, or what is a base. To the word acid, different meanings have been attached at different periods. The original characteristic sourness is no longer deemed essential ! Nor is the effect upon vegetable colours treated as an indispensable characteristic. And as respects obvious properties, can there be a greater discordancy, than that which exists between sulphuric acid, and rock crystal; between vinegar, and tannin; or between the vola- tile, odoriferous, liquid poison, which we call prussic acid, and the inodo- rous, inert, concrete material for candles, called margaric acid ? 2000. While an acid is defined to be a compound capable of forming a salt with a base, a base is defined to be a compound that will form a salt with an acid. Yet a salt is to be recognised as such, by being a compound of the acid and base, to which, as I have stated, it is made an essential mean of recognition. 2001. An attempt to reconcile the definitions of acidity given by Berze- lius, with the sense in which he uses the word acid, will, in my apprehen- sion, increase the perplexity. 2002. It is alleged in his Traite, page 1, Vol. II., "that the name of acid is given to silica, and other feeble acids, because they are susceptible of combining with the oxides of the electropositive metals, that is to say, with salifiable bases, and thus to produce salts, which is precisely the principal character of acids." Again, Vol. I., page 308, speaking of the halogene elements, he declares that " their combinations with hydrogen, are not only acids, but belong to a series the most puissant that we can employ in chemistry ; and in this respect they rank as equals with the strongest of the acids, into which oxygen enters as a constituent principle." And again, Vol. II., page 162, when treating of hydracids formed with the halo^ene class, he alleges " The former are very powerful acids, truly acids, and perfectly like the oxacids ; but they do not combine with salifable bases ; on the contrary, they decompose them, and produce haloid salts." 358 INORGANIC CHEMISTRY. 2003. In this paragraph, the acids in question are represented as pre- eminently endowed with the attributes of acidity, while at the same time they are alleged to be destitute of his "principal character of acids" the property of combining with salifiable bases. 2004. In page 41, (same volume,) treating of the acid consisting of two volumes of oxygen and one of nitrogen, considered by chemists generally as a distinct acid, Berzelius uses the following language. " If I have not coincided in their view, it is because, judging by what we know at present, the acid in question cannot combine with any base, either directly or indi- rectly; that consequently it does not give salts, and that salifiable bases de- compose it always into nitrous acid, and nitric oxide gas. It is not then a distinct acid, and as such, ought not to be admitted in the nomenclature." Viewing these passages with all that deference which I feel for the produc- tions of the author, I am unable to understand upon what principle the ex- clusion of nitrous acid from the class of acids, can be rendered consistent with the retention, in that class, of the compounds formed by hydrogen with " halogene" elements. 2005. It is certainly to be regretted that there should be so much diffi- culty in giving a precise meaning to a word used so extensively as that which led to the language above quoted. The best definition which I can devise, in this case, is that a salt is a compound, resulting from the union of at least two acid, acrid, or corrosive ingredients ; forming, agreeably to the language of the older chemists, a tertium quid, or in plain English, a third something, differing materially from its constituents. It should, as I conceive, be crystallizable, and soluble either in water or alcohol. I do not think that a satisfactory line of demarcation can be drawn between salts, acids, and bases. Some compounds which lean so much towards salinity* in their characteristics, as to have been classed with salts, have latterly been found to play the part of acids or bases, as instanced by the binary halogen salts. I would consider them as salts when acting as such, and as acids or bases when acting as acids or bases. Berzelius has sug- gested this kind of contingent definition in the instance of water ; which he represents as acting as a base with some acids, and as an acid with some bases. Thus it seems possible for the same body to act either as an acid, a salt, or a base, accordingly as it may be associated. Of the Principal Groups of Salts. 2006. As respects composition, I conceive that there are at least three groups of salts. 2007. 1st. Binary saline compounds of a halogen ele- ment and a metal. 2008. 2d. Saline compounds of acids and bases, tertium quids agreeably to the definition of acidity and basidity. (631.) 2009. 3d. Saline compounds containing either an or- ganic acid or an organic base; or consisting of such an acid, united with such a base. * I am unable to refer to any authority for the use of this word, but conceive myself justified in employing it, as, by analogy, it cannot be misunderstood by the reader. OXYSALTS. 359 2010. As far as consistent with the due allotment of time, I have given ah account of the first group in treat- ing of the metals. But the class thus constituted are capable of combining with each other, and with the electro- negative or acid compounds, formed by the union of their halogen ingredients 'with non-metallic radicals. In this way compounds are produced, which Berzelius designates as double haloid salts. I, however, consider them as much entitled to be treated as saline compounds of acids and bases, as the double sulphides, selenides, or tellurides, which are so treated by that distinguished chemist. (627.) 2011. I shall designate the salts comprised in the 1st and 2d groups abovementioned by their basacigen ingredi- ents. (633.) Hence the nine following classes ; oxysalts, sulphosalts, selenisalts, tellurisalts, chlorosalts, bromosalts, iodosalts, fluosalts, and cyanosalts. Obviously, of these the first four are formed by the amphigen bodies, and the rest by the halogen bodies of Berzelius. SECTION I. OF OXYSALTS. 2012. In describing the oxysalts, I shall be constrained to confine my remarks to some of the more important characteristics of each of the sets of salts formed by the different inorganic oxacids with the more energetic bases. Some of those formed by acids of minor importance will be omitted altogether. Of Chlorates and Hypochlorites. 2013. As agreeably to the premised arrangement, the oxacids, first made the objects of attention in this work, were those formed by the union of chlorine with oxygen ; it follows that the saline combinations formed by those acids with bases, should be the first to be treated of among oxysalts. 2014. We have four acids consisting of the two ele- ments abovementioned, and, consequently, should have four species of salts, hypochlorites, chlorites, chlorates, and perchlorates, or oxychlorates. It seems, however, doubtful whether chlorous acid can be presented to a base, without being resolved into a chlorate and chlorine. In this respect, it seems to rest on the same footing as ni- 360 INORGANIC CHEMISTRY. trous acid. (984, 2004.) Of course there are no chlo- rites. 2015. The chlorates and hypochlorates are the products of one process, in which an oxybase is made to react with chlorine. In the process alluded to, a fixed alkali, or any of the three more powerful alkaline earths, whether in solu- tion, in a state of suspension, or in the pulverulent state of a hydrate, being sufficiently exposed to chlorine, is found to acquire the bleaching and disinfecting properties with which that gas is so remarkably endowed. 2016. In the case in which a solution of potassa is saturated with the gas, besides the acquisition of bleaching power, by the mother water, crystals result of chlorate of potash, which from their inferior solubility precipitate. 2017. This process was rather an empyrical improve- ment, when first employed; because, agreeably to the science of the day, nothing could have been less likely to succeed. At that time, chlorine was considered as an oxacid of an unknown radical. (886.) But if the bleach- ing and disinfecting properties of chlorine were due to acidity, nothing could be less consistent with the retention of those properties, than saturation with powerful bases. Subsequently, when the elementary character of chlorine became known, the ascertained retention of its bleaching and disinfecting power, after combination with an oxy- base, appeared much more consistent with the supposed nature of the ingredients. 2018. It was conceived, that chlorine feebly attracted to an oxybase, was liberated by its affinity for colouring- matter, or feculent emanations, or by the affinity of any other principle for the oxybase. Accordingly, until within the last ten years, the impression generally prevailed, that the liquids, powders, or salts employed in bleaching, were compounds of an oxybase with chlorine. Hence, the terms chloride of lime, or chloride of potassa, or of soda, which are still in use, especially among manufacturing chemists. 2019. It was in the treatise of Berzelius, that I first met with the explanation which I gave in the- last edition of this text book, of the process under consideration, and which I now subjoin. 2020. When into a solution of potash, (oxide of potas- sium,) chlorine is introduced, one portion of it combines OXYSALTS. 361 with the potassium, separating from each atom the atom of oxygen by which it was oxidized. The oxygen thus liberated from several atoms of the metal, coming into contact with another portion of chlorine, forms with it chlorous acid. Each atom of the acid, thus formed, unites with an atom of potash, producing a chlorite. By con- tinuing the operation until all the potash which remains free is decomposed, that which has meanwhile united with the acid is attacked by the chlorine, and the oxygen, libe- rated in consequence from each atom of the chlorite, con- verts another portion of this salt into a chlorate. This salt being inferior in solubility to the chloride, precipitates in crystals, which being subjected to boiling water, are purified by the recrystallization which cooling induces. 2021. This explanation seems to require modification, only so far as to introduce the hypochlorous in lieu of the chlorous acid, (688,) agreeably to the new view of the subject presented in treating of the compounds of chlorine with oxygen. Reference is there made to the investiga- tions of Balard, by which it has been shown that the gase- ous product supposed to be the protoxide of chlorine, called euchlorine by Davy, is really a mixture of chlorous acid with chlorine; and also that the real protoxide of chlorine, is the acid which is formed during the process for making chlorate of potash, or bleaching powders, and which is now designated as hypochlorous acid. 2022. The impure hypochlorite of lime, called bleach- ing salt, is obtained by exposing hydrate of lime to chlo- rine. Analogous salts of potash and soda are found in the mother waters of the chlorates of those alkalies, and may likewise be obtained, by double decomposition, from the hypochlorite of lime; and carbonate of potash or soda. When obtained by these methods, hypochlorites are min- gled with the chlorides of the metals peculiar to their respective bases. 2023. Properties. The hypochlorites are extremely susceptible of decomposition. This, however, takes place in a manner which varies with the circumstances in which they are placecl. Bleaching or disinfection is effected by them when quite pure, by imparting oxygen; being re- solved into this element and a chloride. Chlorine pro- duces similar effects, by causing water to impart oxygen. No doubt the result is the consequence of complex affinity, 46 362 INORGANIC CHEMISTRY. the hydrogen being attracted by the chlorine, the oxygen by some oxidizable substance. 2024. When carbonic acid has access to an hypochlo- rite, it combines with the base of the salt, displacing the acid; and if a chloride be present, its radical is oxidized by the oxygen of the acid thus displaced; while its chlo- rine is liberated, as well as that of the chlorous acid. Of course an evolution of chlorine must ensue from the employment, in like case, of any acid, which, in its affini- ties, is not less energetic than carbonic acid. If, however, a pure hypochlorite, formed by the action of hypochlorous acid on a base, be subjected to the action of a more powerful acid, the hypochlorous acid may be liberated without being decomposed. 2025. When an aqueous solution of a hypochlorite is boiled in pure water, one portion of the chlorite is con- verted into a chloride; while the oxygen, which is libe- rated from it during this transformation, converts another portion into a chlorate. 2026. According to Thomson, when chloride of am- monium is introduced into a retort containing the hypo- chlorite of lime of commerce, made into a paste with water, gaseous nitrogen is evolved with a reaction so vio- lent, that, in order to delay the extrication until his ar- rangements for collecting the product were completed, he found it expedient to wrap the hypochlorite in blotting paper. Experimental Illustrations. 2027. Production of hypochlorite of lime. Its effects upon colouring matter. Evolution of nitrogen from chlo- ride of ammonium, by hypochlorite of lime. Properties of the Chlorate. 2028. The chlorates resemble the nitrates in deflagrat- ing with combustibles ; but the residuum which they leave is always a chloride; and the deflagration is more power- ful and more easily effected. If chlorate of potash be triturated in contact with sulphur or phosphorus, an ex- plosion ensues. Salts of this class give up their oxygen, and are converted into chlorides, simply by being heated. They are almost all soluble in water. The chlorate of the protoxide of mercury is said to be but sparingly soluble. OXYSALTS. 363 2029. The properties of the chlorates are most con- veniently illustrated by the chlorate of potash, which is an efficient material in several varieties of the matches which are ignited either by contact with sulphuric acid, by fric- tion, or crushing. 2030. Alcohol, or any of the essential oils, oil of turpen- tine for instance, may be ignited by means of chlorate of potash and sulphuric acid. Experimental Illustrations* 2031. Ignition of phosphorus with chlorate of potash by percussion. Explosion of sulphur mixed with the chlo- rate, by trituration. Composition for friction matches con- sisting of chlorate of potash, sulphur, and phosphorus, mingled with gum, exhibited and ignited. About as much chlorate of potash as may be piled upon a half cent, being deposited in a heap amid the inflammable liquid, the af- fusion of concentrated sulphuric acid upon the heap, causes the liquid to be inflamed. Combustion of Phosphorus under Water, by means of Chlorate of Potash and Sulphuric Add. 2032. Let there be two tubes, one within the other, as here represented ; the larger one, closed at the lower end, and containing water; the other open at both ends, the upper orifice funnel-shaped, and the bore about one-twelfth of an inch in diameter. Allow some very small pieces of phosphorus, and a few crystals of chlorate of potash, to fall down to the bottom of the large tube. Then, into the smaller tube, pour some sulphuric acid ; so that, without being much diluted, it may descend upon the chlo- rate and phosphorus. A vivid ignition ensues, in despite of the surrounding water. 2033. The sulphuric acid, uniting with the potash of the chlorate, liberates chlorine and oxygen, which, coming into contact with the phosphorus, cause its combustion. 364 INORGANIC CHEMISTRY. Of Perch/orates or Oxy chlorates. 2034. One of the processes for procuring oxychlorate of potash, has been mentioned in the text, while treating of oxychloric acid, (712,) and another is mentioned in a note. Oxychlorates of other bases, are obtained either by double decomposition ; or by the direct union of the acid, made as already suggested. (713.) 2035. The oxychlorates, in general properties, resemble the chlorates. They appear, however, to be less suscepti- ble of decomposition; since the oxychlorate of potash is not decomposed by any of the acids at ordinary tempera- tures, and does not react as violently with sulphur as the chlorate of potash. 2036. Nearly all of the oxychlorates would appear to be deliquescent, and soluble in alcohol, excepting those of potash, lead, protoxide of mercury, and ammonia. At the temperature of 59, oxychlorate of potash requires for its solution sixty-five times its weight of water. OF NITRATES. 2037. This class of salts is distinguished by deflagrating with charcoal and other combustibles. When the com- bustible is susceptible of acidification, the resulting acid unites always with the base. Thus in the case of char- coal, a carbonate is left ; in the case of silicon, a silicate ; in the case of sulphur, a sulphate ; in the case of arsenic, an arseniate. They differ from the oxysalts containing an acid with a halogen radical (the chlorates for instance,) in leaving an oxide after deflagration, instead of a haloid salt. Thus the nitrate of potash leaves the oxide of potas- sium ; while the chlorate leaves a chloride of potassium. 2038. If subjected to concentrated sulphuric acid, the nitrates, when dry, emit fumes of nitric acid. When added to liquid chlorohydric acid, by dehydrogenating the chlorine, they enable it to act on gold leaf, as it does when presented to this metal in aqua regia. 2039. The neutral nitrates are all soluble, and many of them deliquescent. Experimental Illustrations' 2040. Deflagration of a nitrate upon ignited charcoal, of charcoal and other substances upon fused nitrate of NITRITES AND HYPONITRITES. SULPHATES. 365 potash, soda, copper, or strontia. A nitrate added to liquid chlorohydric acid containing gold leaf, causes the solution of the metal. Decomposition of a nitrate by heat. OF NITRITES AND HYPONITRITES. 2041. It would appear that the compound, which, con- sistently with the practice of the British and French chem- ists, has been designated as nitrous acid, is decomposed when presented to bases, forming a nitrate and hyponitrite. It is. probable, therefore, that there are no salts which properly deserve the name of nitrites, in the sense in which this appellation has been used by the chemists abovemen- tioned. It has already been stated that Berzelius does not admit the existence of any acid intermediate, as respects the quantity of oxygen contained, between nitric and hy- ponitrous acid, and, therefore, calls the acid to which the last mentioned name has been applied, nitrous acid, and of course designates its compounds as nitrites. (984.) The hyponitrites of the English and French chemists, or nitrites of Berzelius, resemble the nitrates in most of their properties ; but may be recognised by the red vapours which they evolve on the addition of any of the stronger acids. (981, &c.) OF SULPHATES. 2042. Their solutions all yield precipitates with solutions of baryta. Heated in contact with charcoal or hydrogen, they are converted into sulphurets, which, if moistened, smell like rotten eggs. They are almost all insoluble in alcohol. The sulphates of baryta, tin, antimony, bismuth, and lead, are quite insoluble in water. Those of strontia, lime, yttria, mercury, silver, and the sesquioxide of ce- rium, are nearly insoluble; while all other sulphates are soluble. Experimental Illustrations. 2043. Precipitation of sulphates by solutions of baryta. Conversion of a sulphate into a sulphuret before the blow- pipe, demonstrated by the subsequent effect upon a metal- lic solution. 366 INORGANIC CHEMISTRY. OF HYPOSULPHATES, SULPHITES, AND HYPOSULPHITES. 2044. The hyposulphate of baryta, is obtained by adding sulphide of barium to a solution of hyposulphate of manganese. (764.) The hypo- sulphates of lime and strontia are procured in the same manner, and the hyposulphates of the other bases, either by double decomposition, or by adding the acid directly to the base. 2045. The neutral hyposulphates are probably all soluble. This pro- perty, together with their conversion into sulphates by heat, and the odour of sulphurous acid which they emit on the addition of concentrated sul- phuric acid, is sufficient to enable us to recognise them. 2046. The insoluble sulphites are obtained by double decomposition; those which are soluble, by the direct action of the acid on the base. 2047. The sulphites are generally insoluble, and may be recognised by the odour of sulphurous acid which they emit on the addition of diluted sulphuric acid ; while they do not, like the hyposulphites, simultaneously deposite sulphur: also by their not yielding, like the hyposulphates, a neu- tral sulphate by heat. 2048. The hyposulphites are procured by treating metallic zinc, iron, or manganese, with liquid sulphurous acid. Each atom of this acid abandons one atom of oxygen to the metal, being consequently converted into hypo- sulphurous acid, which, with the resulting oxide, forms a hyposulphite. 2049. The hyposulphites may likewise be formed by boiling sulphites with flowers of sulphur, by which each atom of acid in any sulphite takes up an additional atom of sulphur, converting the sulphite into a hyposul- phite. 2050. The hyposulphites may all be decomposed by heat, and, when acted on by sulphuric acid, deposite sulphur and liberate sulphurous acid. OF SELENIATES. 2051. The seleniates greatly resemble the sulphates in properties. They are in fact isomorphous with them, and crystallize with the same quantity of water of crystallization. The seleniates are, however, more susceptible of decomposition than the sulphates, and when thrown on burning coals deflagrate. OF PHOSPHITES. 2052. The phosphites are obtained either by presenting the acid directly to the base, or by double decomposition. When thrown on burning coals they produce a yellow flame, the colour of which increases in intensity with the quantity of acid contained in the salt. OF PHOSPHATES. 2053. The phosphates all give precipitates with solutions of baryta, lime, lead, and silver. 2054. The phosphates are not decomposable by heat alone. Those of the metals proper may be converted, by heat and charcoal, into phosphurets of the metals peculiar to their respective bases. In the case of the phosphates of the earths and alkalies, a portion of the phosphoric acid CARBONATES. BORATES. SILICATES. 367 is deoxidized by the carbon, evolving phosphorus; while the remainder forms with the base a subphosphate. 2055. By heat the phosphates are converted into para- phosphates, identical in composition, though different in properties. 2056. According to Thenard, phosphoric acid combines with bases in five different proportions, forming biphos- phates, sesquiphosphates, neutral phosphates, sesquibasic phos- phates, and bibasic phosphates, in which the equivalents of acid to those of the base are respectively as 2 to 1, II to 1, 1 to 1, 1 to li, and 1 to 2. OF CARBONATES. 2057. This class of salts is distinguished by being sus- ceptible of decomposition, with effervescence, by any of the acids, excepting a few that are remarkably feeble, as, for instance, the cyanhydric and meconic acids. 2058. All the alkaline carbonates are decomposable by heat, excepting those of potassa, soda, baryta, strontia, and probably hthia. 2059. Each of the alkalies, potash, soda, and ammonia, forms with carbonic acid, a carbonate, consisting of an equivalent proportion of each ingredient; a sesquicarbon- ate, in which there are one equivalent and a half of acid to one of alkali; and a bicarbonate, in which there are two equivalents of the acid to one of alkali. When satu- rated with the acid, they are more susceptible of crystal- lization, and less nauseous to the taste. 2060. The evolution of the acid from the carbonates of lime and ammonia has been already exhibited. OF BORATES. 2061. The biborate of soda is found in nature in certain lakes, and is known in commerce as borax. In the examination of minerals by the blowpipe, it is very useful. 2062. The other soluble borates, which are those of potash, soda, lithia, and ammonia, are obtained by uniting the acid directly with the base. The borates, which are quite or nearly insoluble, are procured by double de- composition with the borate of soda. Borates are undecomposable by heat, when their bases are undecomposable by that agent. Other borates, when intensely heated, are resolved into oxygen, a metallic radical, and boric acid. OF SILICATES. 2063. The silicates are procured either by double decomposition, or by heating silicic acid strongly with the base. They are not decomposable by 368 INORGANIC CHEMISTRY. heat alone; although, when heated with charcoal, some of the silicates are converted into silicurets. All the silicates, excepting those of potash, soda, and lithia, are insoluble. OF CYANATES AND FULMINATES. 2064. The soluble cyanates are decomposable by water, and, if insolu- ble, by acids, into carbonic acid and ammonia. The fulminates are chiefly remarkable for the violent explosions which they produce by heat or per- cussion. The fulminate of mercury is employed as priming in percussion gun locks. It may be obtained by the following process : Dissolve 100 grains of mercury with heat in a measured ounce and a half of nitric acid of moderate strength ; when cold, mix the solution with a measured ounce and a half of alcohol, and apply heat till effervescence takes place. When red fumes appear, check the action with water. The powder which preci- pitates, well washed with water, and afterwards dried at a gentle heat, will be the fulminate of mercury. OF DOUBLE OXYSALTS. 2065. There are many cases in which two salts, formed by different bases but of the same acid, enter into combination. A compound thus con- stituted, formerly received the appellation of a triple salt, but is now desig- nated as a double salt. 2066. Tartar emetic is a double tartrate, consisting of tartrate of potash combined with tartrate of antimony. (1919.) 2067. Rochelle salt is a compound of tartrate of potash with the tartrate of soda. An analogous compound is formed by the union of tartrate of pot- ash with tartrate of iron, called ferri et potassce tartras, or tartrate of potash arid iron, in the United States' Dispensatory ; to which I refer stu- dents for much valuable information which my limits will not allow me to add. 2068. The saline compound, well known under the name of alum, is composed of one atom of trisulphate of alumina, and one of sulphate of pot- ash, besides twenty-four atoms of water of crystallization. 2069. Other double sulphates have been formed analogous to alum, sub- stituting soda or ammonia for potash, or iron, manganese, or chromium for alumina. 2070. Double silicates and carbonates exist in nature. Dolomite is a species of marble," consisting of the carbonates of lime and magnesia in equivalent proportions. Felspar consists of a silicate of alumina and a sili- cate of potash. Many native crystals, well known to mineralogists, are double silicates. 2071. Glass, in general, is a combination of one or more silicates. Flint glass, according to Turner, is a double sexsilicate of lead and potash. 2072. It ought not to be supposed that double salts are always produced by the combination of single salts previously existing separately. In the case of tartar emetic, the bitartrate of potash, containing two equivalents of acid to one of base, is converted into the double tartrate of potash and anti- mony, by saturating with one equivalent of the sesquioxide of this metal, one equivalent of the acid in the bitartrate. Thus a tartrate of antimony is produced in combination with a tartrate of potash, and a double salt is of course formed. 2073. It appears possible for two double salts to combine, as when bibo- SULPHOSALTS. SELENISALTS AND TELLURISALTS. 369 rate of soda (borax) is added to bitartrate of potash, in order to produce the " soluble cream of tartar" of pharmacy. According to Berzelius, this compound may be considered as consisting of a double tartrate of potash and soda (sal Rochelle), combined with a double tartrate of potash, and boric acid acting as a base. See United States' Dispensatory. SECTION II. OF SULPHOSALTS. 2074. Berzelius alleges that the metallic sulphides, which are capable of combining with each other to form sulphosalts, contain for each atom of radical, the same number of atoms of sulphur, as the salifiable oxybases and oxacids of the same radicals contain of oxygen. In consequence of this analogy in composition, if sulphydric acid gas be transmitted through a concentrated solution of an oxysalt, in which the acid and base have each a metallic radical, the hydrogen of the sulphydric acid takes all the oxygen from both radicals. Meanwhile, an equivalent number of atoms of sulphur, consequently liberated, take the place of the oxygen, forming a sulphosalt, consisting of a sulphacid and a sulphobase, analogous, in the number of atoms of each ingredient, to the oxysalt, from the decomposi- tion of which it originates. 2075. In order, however, to effect the combination of the electro-positive metallic sulphides which act as bases, with the sulphides of non-metallic radicals which act as sulphacids, a different method must be adopted. In the case of sulphydric acid gas, which does not combine, except with the sulphides of the metals of the alkaline earths and alkalies, it is either brought into contact with a carbonate of the base heated to redness, or else made to enter into a solution of the hydrate. Whichever method be adopted, no access of atmospheric oxygen should be allowed. In either case, one portion of the sulphydric acid is decomposed, its hydrogen com- bining with the oxygen of the base, and its sulphur with the metal ; while the other portion of the acid unites with the sulphide thus formed, pro- ducing a sulphydrate. 2076. It has been stated, (1248,) that combinations of sulphocarbonic acid may be formed with most of the electro-positive sulphides, either by direct union, or by double decomposition. There are other methods of pre- paring these sulphosalts, of which I cannot treat, consistently with the limits prescribed for this work. SECTION III. OF SELENISALTS AND TELLURISALTS. 2077. As has been already stated, both selenium and tellurium are capable of combining with different radicals, forming selenides and tellu- rides. These, in many cases, like the corresponding compounds formed by sulphur, unite together to form selenisalts and tellurisalts. The resulting combinations, however, have been but little studied. 47 370 INORGANIC CHEMISTRY. SECTION IV. OF CHLOROSALTS, BROMOSALTS, IODOSALTS, AND FLUOSALTS OF THE SECOND GROUP. 2078. The chlorosalts are generally obtained by mingling chloracids with chlorobases (631), either in the wet or dry way. In the latter case, heat must be employed in order to facilitate their union. 2079. The bromosalts and iodosalts may in general be obtained in the same manner, by mingling;bromacids with bromobases, or iodacids with iodobases. 2080. I have mentioned, in treating of the chlorides of the metals, seve- ral instances in which combinations are formed by them with chlorohydric acid. Such compounds, however, are rare, and, when they do occur, ap- pear not to possess stability. 2081. I have stated (1396,) my opinion that the compounds, designated by Berzelius as fluohydroboric acid and fluohydrosilicic acid, should be considered as tertium quids, in which the fluoride of hydrogen performs the part of a base, while the fluorides of boron and silicon act as acids. Hence fluohydroboric acid is a fluoborate of hydrogen, and fluohydrosilicic acid, a fluosilicate of hydrogen. 2082. With the fluorides of columbium and titanium, the fluoride of hydrogen forms compounds analogous to those abovementioned, and which I would designate as fluocolumbate, and fluotitaniate of hydrogen. 2083. When any fluosalt like those abovementioned, in which hydrogen exists as a radical, is brought into contact with an oxybase, of which the radical is capable of forming a fluobase, the hydrogen unites with the oxy- gen of the oxybase, while the radical of this base unites with the fluorine. The fluacid of the fluosalt, consequently liberated, combines with the re- sulting fluobase. 2084. The other fluosalts are formed by the direct reaction of the fluacids and fluobases which compose them, either in the wet or dry way. By add- ing fluohydric acid to the fluorides of potassium and sodium, fluohydrates of those fluobases may be formed. (1398.) SECTION V. OF CYANOSALTS. 2085. The cyahosalts are in general obtained either by the direct union of a cyanacid with a cyanobase, or by decomposition. It is by the latter method that the cyanoferrite of potassium is formed, the sulphate of the protoxide of iron being presented to the cyanide of potassium. In this case the sulphuric acid, and the oxygen of the protoxide of iron, are transferred to one portion of the potassium. The cyanogen, consequently liberated, forms with the iron, cyanoferrous acid, which unites with the undecom- posed portion of the cyanide of potassium. (1299. &c.) COMPENDIUM THE COURSE OF CHEMICAL INSTRUCTION THE MEDICAL DEPARTMENT THE UNIVERSITY OF PENNSYLVANIA. BY ROBERT HARE, M.D. PROFESSOR OF CHEMISTRY. PART II. COMPRISING THE CHEMISTRY OF ORGANIC SUBSTANCES; BEING A COMPENDIOUS SELEC- TION FROM THE PREVIOUS EDITION: THE "TREATISE OF ORGANIC CHEMISTRY," BY LIEB1G: GREGORY'S TURNER: KANE'S "ELEMENTS," AND THOSE OF GRAHAM: INTERSPERSED WITH SOME ORIGINAL MATTER. Also, a Letter on the Berzelian Nomenclature, with the Reply of Berzelius ; with some Subsequent Remarks and Suggestions by the Author. And an Effort to Refute the Arguments advanced in favour of the Exist- ence of Compound Radicals, like Cyanogen, in the Amphide Salts. PHILADELPHIA: SOLD BY J. G. AUNER, No. 333 MARKET STREET, AND CAREY & HART, CORNER OF FOURTH AND CHESNUT STREET. John C. Clark, Printer, 60 Dock Street. 1843. OF ORGANIC CHEMISTRY, OR THE CHEMISTRY OF ORGANIC SUBSTANCES. CONTENTS. Organic substances defined Ultimate elements Of organic hydrates, Prout's opi- nion respecting Influence of heat upon vegetables, with and without access of air Ultimate analysis of organic substances Of the mode in which their ulti- mate elements are associated Of compound radicals Of substitution, Page 373 to 379 OF COMPOUND RADICALS. Of amide Carbonic oxide Benzule, benzoile, or benzyl Cinnamyl Salicyl Ethyl Acetyl Kacodyl Mesityl, or misitylene Methyl Formyl Amyl Glyceryl Cetyl, - - Page 380 to 398 OF NUTRITIOUS VEGETABLE SUBSTANCES DEVOID OF NITROGEN. Of Gum Sugars Grape sugar Sugar of milk Mushroom sugar Fermentable matter of diabetes Liquorice sugar Manna sugar, - Page 400 to 406 Of fecula, or starch Of diastaste, and of the conversion of fecula into dextrine and grape sugar Lignin, - Page 406 to 409 OF VEGETO-ANIMAL SUBSTANCES. Of gluten Vegetable albumen Gluten and albumen of wheat Legumen, or ve- getable caseine, - Page 411 to 413 Composition of vegetable fibrin, vegetable albumen, vegetable caseine, and vegeta- ble gluten Composition of animal caseine, Page 418 to 419 OF VEGETABLE COLOURING MATTER. Of vegetable colouring matter, or dyes, and of dyeing Of the colouring matter of leaves and flowers, Page 419 to 420 OF OILS. OF FIXED OILS. Of stearine Margarine Olein Saponification Properties of the fixed oils, Page 424 to 426 OF VOLATILE OILS. Of the resemblance and dissimilarities of the fixed and volatile oils Volatile oils in particular Volatile oils containing sulphur as an ultimate element Volatile oil of mustard Volatile oils containing oxygen Volatile oils devoid of oxygen Of oil of turpentine Camphor Artificial camphor Camphene, or camphelene, and terebene Kreosote Essential oils which are hydrurets Hydruret of ben- zule, or oil of bitter almonds Amiduret of benzule, or benzamide, Page 429 to 442 IV CONTENTS. OF SUBSTANCES MORE OR LESS RESINOUS. Of resins Wax Caoutchouc, or gum elastic, and caoutchoucine Balsams Gum- resins Opium Bitumen, petroleum, naphtha, amber, and mineral coal, Page 442 to 452 OF ACIDS. 'Of acids relatively to the proportions of base required for their saturation Formula for monobasic salts Of acetic acid Pyroligneous acid Acetates Acetate of ammonia, or spirit of mindererus Lactic acid Citric and malic acid Tartaric acid, and paralartaric, or racemic acid Liquid and solid pyrotartaric acid Gui- acine, or guaiacinic acid Tannic acid Artificial tannin Gallic acid Meconic acid A method of detecting the presence of opium Acids formed from sugar Formic acid Valerianic acid Caffeic acid and caffee tannic acid Acids modi- fied by an union with organic matter Acids modified by union with an oxidized compound radical Sulphovinic acid, or the sulphate of ether, and water Suc- cinic acid Benzoic acid Properties of benzoic acid Hippuric acid The hip- purates Formobenzulic acid, - Page 453 to 478 Of salicylous or saliculous acid, also called the hydruret of salicyl, but more pro- perly considered as salicohydric acid, and other compounds of salicyl Of the acids from the oil of gaultheria, - - Page 479 to 482 Saliculous acid with bases Saliculate of ammonia Saliculimide Saliculite of pot- ash; neutral Saliculites of soda, lime, baryta, and magnesia Basic saliculite of lead Saliculite of silver Melanic acid Saliculic acid Chlorosaliculic acid Chlorosaliculimide Bromosaliculic acid lodosaliculic acid Nitrosaliculic acid, - - Page 480 to 482 OF URIL AND URIC ACID. Of uric acid Allantoin Alloxan Alloxanic acid Mesoxalic acid Mycomelinic acid Parabanic acid Oxaluric acid Thionuric acid Uramilc Uramilic acid Alloxantin Products of the decomposition of alloxantin Murexide Mu- rexan On the influence of benzoic acid in lessening the generation of uric acid in human urine, - Page 484 to 492 OF ORGANIC ALKALIES OR BASES. Table of the organic alkalies Organic alkalies of doubtful existence Of the state in which the organic alkalies exist in the products of vegetation, and the means of extricating them, generally described, Page 493 to 496 Of morphia Paramorphia Codeia Narcotina Narcea Quinia On the reaction of chlorine with quinia and its salts Of cinchonia Aricina Strychnia Bru- cia Delphia Veratria Sabadilla Jervina Colchicina Emetia Solania Caffein Chelerythrina Chelidonia Atropia Aconitia B^lladonia Datu- ria Conina Nicotina Lobelina Picrotoxine Antiarine Bases from the oil of mustard Thiosinnamina Sinnamina Sinapolina Cinchovine Cisampe- lina Hederina, surinamina, and jamaicina, Page 496 to 518 Of certain general characteristics of the vegetable alkalies, distinguishing them from inorganic bases, and of those which distinguish them into several different sets. Constitution of the organic alkalies, Page 518 to 520 OF IMPORTANT NEUTRAL ORGANIC PRINCIPLES. Ofsalicin, a neutral principle, and of some compounds derived from it, or to the production of which it contributes Saliretine Chlorosalicine Rutiline Phlo- ridzine Phloridzeine Asparao-ine, asparamide, altheine, agedoile Taraxacine, Page 521 to 524 Of certain Vegetable Principles devoid of Nitrogen. Of gentianine Santonine Picrolichenine Cetrarine Elaterine Colocynthirie Byronine Mudarine Scillitine Cathartine Xanthopicrine Columbine Quassiine Lupuline Lactucine Ergotine Porphyroxine Saponine Smi- lacine Senegine Guiacine Plumbagine Cyclamine Peucedanine Impe- ratorine Yanghinine Meconine Cubebine, - Page 524 to 527 CONTENTS. V OF ETHERS, AND THEIR COMPOUNDS AND DERIVATIVES. OF ETHYL ETHERS. Of the oxide of ethyl, common ether, erroneously called sulphuric ether Of the properties of the oxide of ethyl, and of the means of obtaining it Of heavy oil of wine ; also of light oil of wine Of Hoffman's anodyne liquor Of alcohol, or the hydrated oxide of ethyl Of ethero-sulphurous acid, or sulphurous ether Of hyponitrite of the oxide of ethyl, called nitric ether, or nitrous ether Of the process for sweet spirit of nitre Of the perchlorate of the oxide of ethyl, or per- chloric ether Of acetic ether, or acetated oxide of ethyl Of oxalic ether, or oxalated oxide of ethyl Of carbonic ether, or carbonated oxide of ethyl For- miated oxide of ethyl, or formic ether Of benzoated oxide of ethyl, or benzoic ether Of the tartrate and citrate of the oxide of ethyl, and other " salts" of ethyl, so called, of minor importance Of cenanthated oxide of ethyl, or renan- thic ether, - - Page 529 to 544 Of Simple Ether 's, formed by the Substitution of another Basacigen Body for Oxygen in the Oxide of Ethyl; or for the Hydrogen in the Water united with that Oxide. Of chloride of ethyl Bromide of ethyl Iodide of ethyl Sulphide of ethyl Sal- phydrate of the sulphide of ethyl, or mercaptan Bisulphide of ethyl Selenide of ethyl Telluride of ethyl Cyanide of ethyl, - Page 545 to 546 Of the Dehydrogenation and Oxidation of Ethyl, as contained in Ether or Alcohol, and of the Oxidation of the Residual Products. Of the hydrated oxide of acetyl, called aldehyde Ammoniated aldehyde, or the hy- poacetite of ammonia Acetal, a compound of aldehyde with ether Resin of aldehyde Metaldehyde Elaldehyde, - Page 547 to 549 Of some interesting Results of the Substitution of Chlorine, Bromine, Sul- phur, and other Basacigen Bodies, for the Hydrogen or the Oxygen in the Compounds of Ethyl and Acetyl. Of the chlorohydrate of the chloride of acetyl Chloride of acetyl Bromohydrate of bromide of acetyl, Bromide of acetyl, lodohydrate of iodide of acetyl Chlo- roplatinate of chloride of acetyl Oxychloride of acetyl Oxysulphide of acetyl Chloroxalic ether Chloral, - - Page 549 to 550 OF METHYL ETHERS. Of the oxide of methyl, or methylic ether Of hydrated oxide of methyl, called py- roxylic, or wood spirit, methylic alcohol Neutral sulphated oxide of methyl Acid sulphated oxide of methyl, bisulphated oxide of methyl, sulphomethylic acid Nitrated oxide of methyl Of the hyponitrite of the oxide of methyl, or methylic hyponitrous ether Oxalated oxide of methyl Formiated oxide of methyl, Page 551 to 555 Reaction of Chlorine, Iodine, Cyanogen, and Sulphur, with Methyl, and its Compounds. Chloride of methyl Iodide of methyl Fluoride of methyl Cyanide of methyl Sulphide of methyl Sulphydrate of sulphide of methyl, or methylic mercap- tan Perchloride of carbon, Page 555 to 556 OF FORMYL ETHERS. Compound of hydrated oxide of formyl with oxide of methyl, or methylal For- miated oxide of methyl Artificial oil of ants, Page 556 to 557 Compounds of Formyl with Chlorine, Bromine, Iodine, and Sulphur. Protochloride of formyl Bichloride of formyl Perchloride of formyl, chloroform Chlorohydrate of the chloride of formyl Perbromide of formyl, bromoform Periodide of formyl, iodoform Sulphide of formyl, Page 558 to 559 VI CONTENTS. Of Xylite, or Lignone. Mesiten Mesite Xylite naphtha Xylite oil Methal, - Page 559 to 560 OF THE ETHEREAL COMPOUNDS OF MESITYL, OR MESITYLENE. Of the chloride of mesityl Oxide of mesityl Chloride of pteleyle Of the nitrated oxide of pteleyle Mesitic aldehyde, or the hydrated oxide of pteleyle, Page 560 to 561 OF AMYL ETHERS. Of the hydrated oxide of amyl, or oil of potato spirit, or amylic alcohol Acetated oxide of amyl, amylo acetic ether Of the bromide and iodide of amyl, Page 561 to 562 OF ANIMAL SUBSTANCES. Indifferent nitrogenized substances common to the vegetable and animal kingdoms proteine and its modifications, - - 564 Modifications of proteine, - - - 565 The blood, - 569 Brain and nervous matter, - - 572 Animal secretions and excretions, - - 574 Bile and biliary calculi, - - - 576 Urine and urinary calculi, - - 579 Changes which occur during the life, growth, and nutrition of vegetables and animals, - - 582 Of Respiration, - 593 Of Fermentation, - 596 Of the saccharine and vinous fermentations, - - 597 Of the acetous fermentation, a process of acetification, - 598 Of the lactic or viscous fermentation, - 598 Of the Putrefactive Fermentation, - - 604 OF ORGANIC CHEMISTRY, OR THE CHEMISTRY OF ORGANIC SUBSTANCES. 2086. , Under the appellation of organic substances are comprised 2087. 1st. All those which are created in vegetables and animals. 2088. 2dly. Such as are generated from those above mentioned, either by spontaneous changes, aided by tem- perature or catalysis, or by reciprocal reaction. 2089. 3dly. Such as arise from the substances created or generated as above described, in consequence of their reaction with inorganic bodies. 2090. In this department of the science it is, perhaps, less difficult to acquire some general ideas, than to make an equal progress in the chemistry of inorganic substances. The ultimate elements of vegetable and animal matter are fewer, and are peculiarly well known. But the light which is thrown upon inorganic compounds, by resolving them into their ultimate elements, is much more satisfactory than any which we can, by the same means, extend to or- ganic products. Between these, ultimate analysis can de- monstrate little more than a difference in the proportions of the hydrogen, oxygen, carbon, and nitrogen, of which they are constituted ; although in their influence on vitality they may display the opposite properties of the most de- licious food, or the most deleterious poison; of delighting or offending our senses in the extreme. 2091. Hydrogen, oxygen, and carbon, are the principal ultimate elements of vegetable substances ; especially car- bon, which is pre-eminently essential to their constitution, and has been alleged to perform, in vegetables and ani- mals, a part analogous to that which silicon performs in minerals. 2092. In some essential oils, in caoutchouc, in ammonia 48 372 ORGANIC CHEMISTRY. in cyanogen, and in some compounds formed or derived from these substances, there is no oxygen, while in oxalic acid, and some other oxides of carbon, no hydrogen exists. But in no instance, excepting that of ammonia, and its hy- pothetical associates amide and ammonium, is carbon de- ficient; and in the great majority of instances, the three elements above named are indispensable ingredients. Al- though, comparatively, nitrogen be found only in a few substances, those into which it does enter are generally pre-eminently active in their properties ; and, agreeably to Liebig, without its assistance, vegetation cannot thrive. Hence, as he alleges, it is always to be found in vegetable organs, although not a constituent of many substances which they secrete or excrete. 2093. Magnesium, calcium, sulphur, phosphorus, iron, silicon, bromine, iodine, fluorine, are also found in minute proportions in certain parts of certain vegetable or animal products; and it maybe inferred that they perform some use- ful office; but although subservient, in an important degree, to the functions of animals and plants, they are constituents neither of their organic tissues, nor secretory products. 2094. It is generally a marked distinction, between or- ganic and inorganic products, that the latter can, in a much greater number of instances, be imitated by art. 2095. The incompetency of chemists to regenerate the substances analyzed by them, has caused the accuracy of their deductions to be questioned. Rousseau, having heard Rouelle lecture on farinaceous matter, said he would not confide in any analysis of it, till corroborated by its reproduction from the elements into which it was alleged to have been resolved. I conceive that an acquaintance with facts, thoroughly demonstrable by modern chemistry, would have rendered that ingenious philosopher less scep- tical. At first view it may seem reasonable to consider synthesis as the only satisfactory test of the truth of ana- lysis. But if when diamond is burned in one bell glass, and charcoal in another, in different portions of the same oxygen gas, and subsequently, in each vessel, in lieu of the diamond and charcoal, carbonic acid is found, from which, by potassium, carbon may be liberated, who would hesi- tate to admit both substances to consist of carbon, because this element cannot be recovered in its crystalline form from the gaseous state? INFLUENCE OP HEAT ON VEGETABLES. 373 Of Organic Hydrates. 2096. It was suggested by Prout, that as, in many vege- table substances, consisting only of carbon, hydrogen and oxygen, the two last mentioned elements existed exactly in the proportion for forming water, they might be consi- dered as constituted of water and carbon, and, conse- quently, as hydrates of carbon. 2097. But it has since been shown, that either the hy- drogen of these supposed hydrates, may, in various in- stances, be supplanted by other elements without separa- ting the oxygen; or that the oxygen may be suppjanted without separating the hydrogen. 2093. It is, however, an important and interesting fact, that almost all vegetable substances which are neither acid, oily, nor resinous; such, for instance, as gum, sugar, starch, lignin, hold the elements of water in the ratio re- quisite to form this liquid, however these elements may be associated. Of the Influence of Heat upon Vegetables, with and without Access of Air. 2099. When subjected to distillation, vegetable sub- stances devoid of nitrogen, in the first place, yield the water and essential oils previously existing in them. At a higher temperature, certain essential oils or spirits, analogous to alcohol, resulting from a new arrangement of the ultimate elements, are in some instances evolved; and either at the same time, or subsequently, at a higher temperature, acetic acid, associated with bituminous or empyreumatic matter, with carbonic oxide or carbonic acid, and carburetted hy- drogen are generated. By further ignition, the volatile products thus obtained, may be resolved into carbonic ox- ide and carburetted hydrogen; a deposition of carbon in the solid or pulverulent state, being always a concomi- tant of the change. In proportion as the hydrogen is ra- refied by heat, its capacity to suspend the carbon appears to be diminished (1259). So far as nitrogen is present, by the union of an atom of this element with carbon or hydrogen, ammonia or cyanogen, or some of their com- pounds, may be generated. 3000. The results above mentioned evidently proceed, in a great measure, from the superior volatility of the 374 ORGANIC CHEMISTRY. hydrogen and oxygen, which causes them to pass off into the aeriform state, with such portions of the carbon as they may, under these circumstances, he capable of retaining. 3001. The experiments of Sir James Hall show, that ve- getable matter, wood for instance, when subjected to heat and pressure, is converted into a bitumen analogous to that of mineral coal. Under these circumstances, caloric destroys the organic structure, but does not sever the constituents of many bodies, which would be otherwise partially dissipated. When ignited in the air, it were almost unnecessary to say that hydrogen, oxygen, and carbon must yield water and carbonic acid only. These are the only products of hydrogen and carbon, when burned where there is an ample supply of oxygen. 3002. By a carefully managed heat several vegetable acids may be converted into acids of a different kind. In some instances, difference of temperature is sufficient to vary the character of the resulting acid. Of the Ultimate Analysis of Organic Substances. 3003. The analysis of vegetable and animal matter has been latterly accomplished by heating the substance with oxide of copper, so as to oxidize all the carbon and hydrogen, and liberate, in the gaseous state, any nitrogen which may be present. The hydrogen has been in general estimated from the water produced; the carbon, from the quantity of carbonic acid. Hence the products of the operation have been first passed over chloride of calcium, and after- wards subjected to hydrate of potash, lime-water, or alka- line solutions. The- water is estimated from the increased weight of the chloride, and the carbonic acid by the vo- lume absorbed, or the increased weight of the alkaline so- lution employed for its detention. 3004. By Messrs. Will and Varrentrapp, the proportion of nitrogen in a compound has lately been ascertained by heating it with a mixture of quicklime and hydrate of soda, in a tube of refractory glass. Under these circum- stances, the element in question, uniting with hydrogen to form ammonia, is easily secured by means of a dilute so- lution of chlorohydric acid. The resulting chloride of am- monium is precipitated by chloroplatinic acid, and the re- sulting salt is washed in a mixture of ether and alcohol. The quantity of nitrogen is estimated by the table of equi- ULTIMATE ANALYSIS OF ORGANIC SUBSTANCES. 375 valents, and by ascertaining the loss of weight consequent to exposure to a red heat. Agreeably to the table of equivalents, w of the loss thus sustained is nitrogen. 3005. When chlorine is present, chromate of lead is used in lieu of the oxide of copper, because the chloride of copper, being volatile, would be carried into the cavities employed for the absorption of water and carbonic acid. 3006. When liquids are to be analysed, small portions are introduced into glass bulbs so as "to alternate in a tube with oxide of copper, or some other oxidizing agent. Of the Mode in which the Ultimate Ponderable Elements of Organic Bodies are associated. 3007. As in the analysis of the mineral kingdom, we de- signate as elementary, those substances which we cannot analyse further, so, in examining organic products, those substances of which the grouping cannot be altered without destroying their most important characteristics, are to be viewed as the elementary principles, by which the nature of compounds is to be understood and described. 3008. Liebig alleges, that the principal object of organic chemistry, is the investigation of the properties and com- position of organic combinations, and the mode in which their elements are grouped. The idea attached to the word grouped in this instance, may be illustrated by contempla- ting the formula of a compound in one way, so as to exhi- bit only the proportions in which each ultimate element exists in it ; in another way, so as to make evident not only their proportions, but their grouping likewise. Thus the formula C 2 O 3 shows, that two atoms of carbon and three of oxygen enter into the composition of oxalic acid ; but CO x CO 2 shows, that this acid is composed of car- bonic oxide CO, and carbonic acid CO 2 (556, &c.). 3009. In like manner, cyanhydric acid may be repre- sented as a compound of two atoms of carbon, one of ni- trogen, and one of hydrogen, C 2 N H, or as a compound of cyanogen, C 2 N and hydrogen, H, formula, C 2 N+H. 3010. The compounds thus cited, CO carbonic oxide, and C 2 N cyanogen, are considered as acting as compound ra- dicals. This appellation is .employed to designate in these instances and in others, certain groups of ultimate ele- ments which appeared to be endowed with the power, like that of simple ultimate elementary atoms, of entering in 376 ORGANIC CHEMISTRY. combination with one or more of their composing atoms, or of other simple elementary or compound atoms. 1 * 301 1. From a deficiency of better words I shall consider a " compound radical," so called by Liebig, as a compound element, when, like cyanogen or ethyl, it acts as a simple element. I shall restrict the use of the name radical, agreeably to the definition in my Inorganic Chemistry, to such bodies as do not form the common ingredient of an acid and a base. 3012. Compound elements, like cyanogen, which, when they unite with an anion and a cathion, form with the former an acid, with the latter a base, I consider as be- longing to the basacigen class (627). 3013. As on the one hand, it is seen that cyanogen per- forms the part of a basacigen body, or one capable of pro- ducing acids and bases, by combining with radicals; so, on the other, we may perceive ammonium, consisting of hy- drogen and nitrogen, N x H 4 , capable like a metallic radi- cal of forming compounds with the basacigen class, which have basic properties in some instances of great energy. But latterly, pursuant to the suggestion of Kane, ammonia is conceived to contain a compound element analogous to cyanogen, consisting of NH 2 which is called amide, and which combines with hydrogen and other radicals, form- ing compounds called amidurets, capable of union with other definite compounds. Thus it is inferred, that white precipitate consists of amide, mercury and chlorine, NH 2 Hg + Cl Hg, the symbol of amide is Ad, which being substituted in the above, we have Ad Hg + Cl Hg for the formula of white precipitate/)" 3014. This view of the subject is now generally sanc- tioned, although neither amide nor ammonium have been isolated. 3015. In fact, it has been shown of late, that there are a * Strictly, an element cannot be compound; but chemists, before the idea of com- pound radicals originated, distinguished compounds capable of entering into com- bination and of being separated again, and transferred to other compounds, as proxi- mate elements, in contradiction to simple elements also called ultimate elements. Upon this view of the subject, the ultimate analysis has been understood to convey the idea of the resolution of a substance into its simple elements, in contradistinc- tion to an analysis by which its proximate elements are separated. Alcohol sub- jected to ultimate analysis would be converted into hydrogen, oxygen and carbon, while by another procedure, it may be resolved into its proximate elements water and ether. I feel myself authorized, under this view, to call those bodies compound elements, which, consisting of more than one element, act like simple elements. I N is the symbol of nitrogen, H of hydrogen, Cl of chlorine, Ad of amide, Hg of hydrargyrum or mercury (556, &c.). OF COMPOUND RADICALS. 377 great number of compound radicals existing in, or arising from, vegetable or animal matter, as capable of uniting with basacigen bodies as do elementary radicals, forming like these, oxides, chlorides, bromides, iodides, fluorides, cyan- ides, sulphides, &c. Of the compounds thus produced, some play the part of a radical in an acid, some an analo- gous office in a base or even of an alkaline base. More- over the acids and bases thus produced, unite similarly to those generated by a union of ultimate elements, which they are in many cases competent to displace from com- bination. 3016. Compound organic radicals may be divided into three classes accordingly, as capable of forming acids, or bases, or neither. Hence, they may be distinguished as acidifiable, as basifiable, or as indifferent. 3017. The acidifiable compound radicals are as follows : Formula. Carbonic oxide or protoxide of carbon, C O Cyanogen or bicarburet of nitrogen, C 2 N Mellon or sesquicarburet of nitrogen, C 6 N 4 Benzoile, benzule or benzyl, C 14 H 5 O 2 Cinnamyl or cinnamule, C 18 H 8 O 2 Salycyl or salicule, C 14 H 5 O 4 Acetyl or acetule, - C 4 H 3 Forrnyl or formule, C 2 H 3018. The basifiable compound radicals are Amide, N H 2 Ethyl or ethule, - C 4 H 5 Methyl or methule, C 2 H 3 Cetyl or cetule, - C 32 H 33 Glyceryl or glycerule C 6 H 7 Amyl or amule - C 10 H 11 Mesityl or misitylene C 6 H 4 Kacodyl or kacodule C 4 H 6 3019. There are likewise some subordinate compound radicals. 3020. As with very few exceptions in formulae expressing the composition of organic substances, only four different letters are requisite, with the figures showing the relative proportions, the employment of symbols for that purpose is evidently highly advantageous. The student, therefore, 378 ORGANIC CHEMISTRY. is advised especially to overcome, by a proper degree of resolution, any repugnance to the study of the formulae above given, or others which may be resorted to in this or in other modern treatises of chemistry. A comparison of their formulae, respectively, will convey an idea of the difference in composition existing between the radicals in the preceding list. 3021. Agreeably to Liebig, the term " compound radical" denotes a class of compound bodies possessing the capacity of uniting with the simple elements, and forming, with them, combinations analogous in their properties to com- binations of two simple elementary bodies. 3022. From combinations formed as above mentioned, the simple element may be removed and replaced by ano- ther element, simple or compound. 3023'. According to the same authority, compound radi- cals are capable of combining with each other, and of forming acids with oxygen, sulphur, or hydrogen. 3024. He assumes that all organic compounds may be arranged in groups, each derived from their appropriate compound radical by the combination of this radical with elementary atoms, and the union of the resulting com- pounds with other compound bodies. 3025. Under the head of crystallization (494), I advert- ed to the fact that certain elements may be substituted, the one for the other, without changing the crystalline form. Dumas has latterly held an analogous doctrine respecting the substitution, in organic products, of one element for ano- ther, or of a compound radical for an element, without " altering the general chemical type" as he calls it ; and would have the bodies thus formed grouped together, con- stituting a natural family. Liebig alleges, that "recipro- cal substitution of simple or compound bodies, acting in the manner of isomorphous bodies, should be considered as a true law of nature." This substitution may take place between bodies which have neither the same form, nor any analogy in composition. It depends exclusively on the chemical force, which we call affinity. 3026. In consonance with the law in question, Dumas has found, that in acetic acid chlorine may be substituted for hydrogen, and that in this way a new acid, designated as chloroacetic, may be produced. . 3027. This chloroacetic apid is by him alleged to be, in OF SUBSTITUTION. 379 its properties, so analogous to acetic acid, that to know the habitudes of the one, conveys an idea of those of the other. This analogy he conceives to arise from a chemi- cal law, agreeably to which the properties of a compound depend rather on the type of the composition, than on the particular character of the elements which may have been exchanged. 3028. Berzelius asserts that chloroacetic acid differs much from acetic acid in properties, and that the facts ad- duced justify nothing beyond an opinion, originally ex- pressed upon the subject by Dumas himself, who, speaking of the law of substitution, admitted it to be an " empirical law, deserving our attention only so long as it might hold good" 3029. It appears to me, that the facts of the cases ad- verted to in the support of the doctrine of substitution, demonstrate them to come under the fourth case of affi- nity (523), in which two bodies, simple or compound, being in union, another body, added in excess, unites with both. 3030. In the case of acetic acid exposed to an excess of chlorine, there is the affinity between hydrogen and chlo- rine, and that between chlorine and the elements, with which hydrogen is previously combined. 3031. Hence results chlorohydric and a new acid, called chloroacetic, in which chlorine may act as a radical, as it is known to do in its combinations with oxygen. The exist- ence of chlorocarbonic acid demonstrates that the display of affinity between chlorine and oxides of carbon, is not an anomaly. 3032. Either of the classes of radicals abovementioned, may be distinguished into primitive and derived radicals. Mellon, a sesquicarburet of nitrogen, is derived from cy- anogen ; and acetyl and formyl, from ethyl and methyl. 3033. Being convinced that in the present state of che- mistry, more even than heretofore, it is best to aim at general knowledge first, and afterwards to proceed to particulars, I shall not treat of the compounds formed with radicals or products obtained from them, under their heads respectively, unless where the substances alluded to are of practical importance. 49 380 ORGANIC CHEMISTRY. Of Amide, NH 2 . 3034. Ammonia, it will be remembered, consists of an atom of nitrogen and three of hydrogen, NH 3 . Amide is assumed to consist of one atom of nitrogen and two of hydrogen, as the formula above given indicates. 3035. The phenomena which ensue when potassium is heated in ammonia, had long been an object of unsuccess- ful speculation. The metal, when so exposed, becomes converted into an olive-coloured mass, which, by contact with water, is converted into potash and ammonia. 3036. I believe that Dr. Kane was the first to suggest, that in this case the alkalifiable metal takes the compound radical, amide, from the ammonia. Thus a compound is generated of amide arid potassium. When the amiduret of potassium, produced as described, is presented to water, this liquid regenerates ammonia, by supplying an additional atom of hydrogen to the amide, while the po- tassium is, by simultaneous oxidizement, converted into potash. It follows that ammonia is an amiduret of hy- drogen. 3037. Compounds of amide are called amides by Liebig ; amidides by Kane; though it will be seen, that when com- bined with hydrogen, Liebig designates the resulting com- pound as a hydruret; in French, hydrure. Consistently with the nomenclature which I have employed, the termi- nation in ide is restricted to the basacigen class ; I shall therefore use the termination in uret for the compounds of amide. It is singular that Liebig should use the same word, amide, for the radical and for its compounds. 3038. As by the subtraction of an atom of hydrogen from ammonia, amide is generated, so, by the addition of a like atom, we generate ammonium, of which I have al- ready treated (1106). 3039. Liebig represents amide as acting with hydrogen in the place of an electro-positive radical. Hence, agree- ably to his language, ammonia is a "hydrure d'amide," in English, a hydruret of amide; or, more briefly, he calls it hydramide. Of course, consistently, ammonium is a bihy- druret, or bihydramide. 3040. The following formula will serve to explain the composition of some of the compounds of amide. It should be kept in mind that Ad is the symbol of amide. White OP AMIDE, CARBONIC OXIDE, &C. 381 precipitate is a compound of amiduret of mercury and bi- chloride, Ad, Hg + Hg CP. Another amido-chloride is formed by the reaction of white precipitate with alkalies, when results a compound of an amiduret with the bioxide and bichloride of mercury, Ad Hg + Hg O 2 -f Hg Cl 2 . Two atoms of amiduret of mercury unite with a subsul- phate, whence we have a biamido-subsulphate, Ad Hg 2 + So 3 2HgO. Biamido-sesquinitrate of mercury consists of two atoms of amiduret of mercury, two of acid, with three of bioxide of the same metal, 2Ad Hg + 2NO 5 3Hg O 2 . Amido-subnitrate, consisting of an atom of amiduret and two of subnitrate, Ad Hg NO 5 2HgO. 3041. White precipitate has been designated as chlor- amide of mercury: I prefer the name, above employed, of amido-chloride. Of Carbonic Oxide as a Compound Radical. 3042. Of this radical I have already treated as an oxide of carbon. By combining with carbonic acid, CO 2 , it con- stitutes oxalic acid, C 2 O 3 . This acid, by combining with hydrated ammonia, NH 3 4- HO, or more properly with ox- ide of ammonium, consisting of the same ultimate elements differently grouped (1116), forms neutral oxalate of ammo- nia, so called. This oxalate is principally used as a test for lime. 3043. Chloroxy carbonic acid is a product of the union of carbonic oxide with chlorine, of which some mention has been made (1240). 3044. Carbamide is the name given to a compound formed Ky the union of carbonic acid with amide. It is obtained by mingling chloroxycarbonic acid with ammo- nia. In this way solid white crystals are produced, con- sisting of carbamide and chloride of ammonium. 3045. Oxamide, C 2 O 2 + Ad, consists, as may be seen from the preceding formula, of two atoms of carbonic ox- ide and one of amide. It may be designated as an amido- oxide of carbon. 3046. This compound is obtained in great purity, by decomposing oxalic ether by liquid ammonia, or by heat- ing an oxalate of ammonia in a retort, with a receiver an- nexed. The oxamide passes into the receiver, and con- denses in white flocks. These, being insoluble in water, are depurated by washing with this liquid upon a filter. 382 ORGANIC CHEMISTRY. 3047. Oxamide is described as a brilliant white powder, insoluble in alcohol, ether, and in cold water, but soluble, in a small proportion, in hot water. 3048. Subjected to dry distillation, it is resolved into water, carbonic acid, cyanhydric acid, cyanic acid, and ammonia. 3049. Oxamide differs from the common oxalate of am- monia, consisting of oxalic acid and oxide of ammonium, in having two atoms less water. 3050. Oxalic ether, which may be decomposed instantly by an aqueous solution of ammonia, consists of anhydrous oxalic acid and ether, or oxide of ethyl. The acid yields an atom of oxygen to one of hydrogen to form water, by which the ether is converted into alcohol, while on the one side there remains carbonic oxide, CO, on the other, amide, NH 2 , which by reciprocal union constitute oxamide. 3051. When oxamide is heated with alkalies or acids, by the accession of an atom of water, oxalic acid and am- monia are generated. The same result ensues from the exposure of a mixture of oxamide and water, to a tempera- ture above the boiling point. Of Benzule, Benzoile or Benzyle, C 14 , H 5 , O 2 . 3052. The preceding name is given to a compound ra- dical inferred to exist in benzoic acid, and in the essential oil of bitter almonds, giving rise to several interesting com- pounds. By the addition of an atom of oxygen and an atom of water,^ it forms crystallizable benzoic acid, which, like many other acids, cannot exist without an atom of water, or some other base. 3053. By the substitution of an atom of hydrogen for an atom of oxygen, benzoic acid is converted into the pure essential oil of bitter almonds, C 14 , H 5 , O 2 , which Liebig designates as a hydruret of benzule. 3054. By bringing either of the halogen bodies (627), or various acids in contact with this hydruret, with or without exposure to the distillatory process, a variety of compounds may be produced. These compounds, in com- position and properties, are somewhat analogous to ethers; inasmuch, as they mix either with ether or alcohol, and re- tain their radical with an energetic affinity. 3055. The hydruret of benzule does not pre-exist in bit- ter almonds, but is the product of the mysterious catalyzing OF BENZULE, CINNAMYL. 383 influence of two substances which they contain, amigdalin and emulsin, or synaptase, in an aqueous mixture when subjected to distillation. During the reaction thus in- duced, cyanhydric acid being generated, endows the resul- ting oil or hydruret, with a well known poisonous proper- ty, which, in the absence of that acid, has been ascertained not to exist. 3056. Benzule forms a compound with amide, called benzamide, by the reaction of chloride of benzule with dry ammoniacal gas; and likewise an acid, by uniting with formic acid, called formobenzulic acid. Hippuric acid, which is the uric acid of the horse, consists probably of benzamide and another peculiar acid; or of hydruret of benzule, with cyanhydric and formic acids. 3057. According to Mr. Alexander lire, benzoic acid taken internally by man, is discharged in the urine as hip- puric acid, the proportion of uric acid undergoing a cor- responding diminution. Cinnamyl, C 18 , H 8 , O 2 . 3058. Between this radical and benzule, there is much analogy ; since cinnamyl plays a part in pure oil of cin- namon, or hydruret of cinnamyl and cynnamic acid, analo- gous to that which benzule plays in its hydruret and in ben- zoic acid. In either case, the substitution of oxygen for hydrogen, converts the hydruret into an acid having the same radical. 3059. Cinnamyl exists in oil of cinnamon, which, when pure, constitutes a hydruret, and in an acid called cynnamic, playing a part similar to that which benzule has been re- presented as performing in two analogous compounds. In either case, the oily hydruret may be converted into an acid having the same radical, by the substitution of an atom of oxygen for one of hydrogen. 3060. This radical is said to exist in an oil, separable from the balsams of Peru and Tolu. 3061. It does not appear that the compounds formed with this radical are numerous or important. 3062. By the reaction of pure colourless nitric acid with Chinese oil of cinnamon, a crystallized nitrated hydruret of cinnamyl may be obtained, C 18 , H 8 , O 2 -f HO + NO 5 , which by addition of water liberates the pure hydruret of cinnamyle, C 18 , H 8 , O 2 . 384 ORGANIC CHEMISTRY. OfSalicyl, C 14 , H 5 , O 4 . 3063. This hypothetical radical is inferred to exist in the oil of the spirea ulmaria or queen of the meadow, and in that evolved from a neutral crystallizable substance, called salicin, which may be extricated from the leaves and bark of any species of willow, of which those parts have a bitter taste; and also from some species of poplar. It was originally discovered by Buchner and Leroux, in the bark of the salix helix. 3064. This radical has a great analogy to benzule in properties, as well as proximity in composition, as must be evident from a comparison of their respective formula. It is in fact benzule plus two atoms of oxygen. 3065. The oil above mentioned has the same relation to salicyl, that the oil of bitter almonds has to benzule, both being hydrurets. The oil of spirea is treated as a hy- dracid, which it will be well to keep in mind when sour- ness is insisted upon, as a property peculiar to what are improperly called hydracids. 3066. This hydruret may be obtained in a state which is isomeric, if not identical with that in which it is extricated from the spirea, by distilling one part of salicin with three parts of bichromate of potash, four and a half of sulphuric acid, and thirty parts of water. 3067. It is a colourless, oily, inflammable liquid, with a burning taste; density 1.731, freezing at 4, boiling at 335.7 when obtained from spirea, but 359.6 as obtained from salicin. It dissolves easily in water, alcohol and ether. 3068. Salicyl, like benzule, forms compounds with the halogen bodies, or with acids, by their reaction with its hy- druret. The reaction with ammonia differs from that of benzule, as it unites with the ultimate element, nitrogen, instead of amide. Of Ethyl, C 4 H 5 . 3069. If this be really, as is generally now believed by chemists, the radical in the well known liquid, alcohol, certainly, for good or evil, it is one of the most important and interesting compounds in nature. 3070. In the year 1836, in the last edition of my Or- ganic Chemistry, agreeably to the doctrine prevailing at the time, I treated alcohol as a compound of two atoms of OF SALICYL, ETHYL. 385 water and one of etherine, C 4 H 4 + 2HO. Common ether differing from alcohol only in having an atom less of water essential to its constitution, was represented to be a monohydrate of etherine, C 4 H 4 4- HO. No change has taken place as to the ultimate analysis of these liquids. It is only as to the grouping of the ultimate elemen- tary constituents, by which we have in ether, C 4 H 5 O, and in alcohol the formula of ether, with an additional atom of water, C 4 H 5 O -f HO. Thus, instead of a mono- hydrate of etherine, ether becomes an oxide of ethyl; and alcohol, from a bihydrate of etherine, is transferred into a hydrated oxide of ethyl. 3071. Agreeably to either view, the transformation of alcohol into ether requires only the removal of an atom of water. 3072. It is well known that common ether may be ob- tained by the distillation of alcohol with sulphuric acid, and that when, to the materials employed for this purpose, an acid, or a salt containing an acid, is added, an etherial compound of ether with the acid, having more or less ana- logy with common ether in properties, may be obtained. 3073. There is hardly an acid, with which a peculiar ether bearing its name has not been formed, such as nitric ether, acetic ether, tartaric ether, oxalic ether, muriatic ether, &c. 3074. The rationale is evident : as to convert alcohol into ether, the removal of an atom of water is all that is requisite; to generate -any other ether, it is only necessary that this oxide, in its nascent state, shall be in contact with an acid, or be presented to any basacigen body in union with hydrogen ; so that the ethyl may be deoxidized by the formation of water, and presented naked to the basaci- gen element. 3075. Under this view of the composition of ether, it is unaccountable, that this oxide will not combine with acids, excepting when it is in a nascent state; but this ob- jection may apply also to the existence of etherine as the base of the ethers. 3076. It does not appear that ethyl has ever been iso- lated. I have not only distilled pure ether from potas- sium, without decomposing it, but have likewise cohobated it with potassium in a glass tube, hermetically sealed. The lower end, to which the contents naturally subsided, 386 ORGANIC CHEMISTRY. was kept boiling by a water bath for several days, without being decomposed more than partially. The potassium became coated with a white crust, which being removed, the metal appeared in its metallic state. 3077. The etherial compounds of ethyl may be classi- fied as forming one order of ethyl ethers. 3078. We have then, in this order, the following class- es: Class 1st. Simple ethers, formed by the union of ethyl with any basacigen element which are named after such element. 3079. In this class we have the Oxide Chloride Bromide Iodide Sulphide Selenide Telluride of ethyl, 3080. Complex ethers are formed by the union of an acid with any one of these. Excepting those formed with the oxacids and sulphydric acid, there are no ethers in this class. The oxacid ethers may be considered as form- ing a genus comprising an etherial compound for almost every acid of importance. 3081. There is only one sulphacid ether, mercaptan, or the sulphydrate of the sulphide of ethyl. 3082. In consequence of its being obtained by the dis- tillation of sulphuric acid with alcohol, the oxide of ethyl was formerly called sulphuric ether, and is still mentioned under that name in commerce, agreeably to the opinion that it consisted of water and etherine, as other ethers consisted of etherine and an appropriate acid. In the last edition of my Organic. Chemistry, I designated this oxide as hydric ether. It is a curious consequence of the change which has taken place, as above described, in the prevail- ing opinion on this subject, that the name above mentioned is now due to alcohol, which, as respects composition, is, in fact, hydric ether. Yet it differs from ethers in general in having a strong affinity for water in all proportions. 3083. It may be well to premise, that I shall adopt for the oxide of ethyl, when not particularly desirous to recall its chemical composition, the usual name of ether, which OF SALICYL, ETHYL. 387 it may claim by prescription, however temporarily it may have been otherwise designated. 3084. As alcohol differs from ether only in the presence of an atom of water, it follows that any chemical reaction, which should effect the removal of that atom, ought to convert it into ether. Yet, excepting the reaction, during distillation, with one or two chlorides, a resort to which would not be found economical, the conversion of one li- quid into the other is accomplished by a most complicated and intricate play of affinities, which has been a most pro- lific source of discussion among the most eminent che- mists. Nevertheless, this subject is still debateable, not- withstanding that much light has been thrown upon the ac- companying phenomena. 3085. It may be well for the student to recollect the relative composition of these important liquids, and that the conversion of one into the other arises from the sub- jection of alcohol, mingled with certain acids, to the dis- tillatory process. 3086. When sulphuric acid is employed as is usual, the first result is a combination between two atoms of this acid, one of oxide of ethyl, and one of water, forming what has been called, heretofore, sulphovinic acid, or what Lie- big designates as the acid sulphate of the oxide of ethyl. 3087. Evidently it would be more properly defined as a double sulphate of ether and water ;* for as, what is called concentrated sulphuric acid, when deprived of water as far as this effect can be produced by ebullition, is a sulphate of water; sulphovinic acid, consisting of one atom of this sulphate, and one atom of sulphate of the oxide of ethyl, must be a;'double sulphate of the oxide of ethyl, and wa- ter.f 3088. So long as the proportion of water present in * The water in hydrous sulphuric acid, has been latterly considered as acting as a base, so that when a metal, by contact with the acid, displaces hydrogen, it is mere- ly a case in which one radical supplants another. Agreeably to a new doctrine, all the sulphur and oxygen present, acts as a compound radical, and, as such, is trans- ferred from one radical to another; but this I think I have shown to be untenable. See Effort to refute the Arguments in favour of the existence of Compound Radicals in Amphide Salts, 6, 92. t In order to understand the above given explanation, it should be recollected, that the boiling point of diluted sulphuric acid rises, as the proportion of water in union with it lessens, till it attains the point at which the sulphate of water itself vaporizes, which is about 600 : also, that the affinity of concentrated sulphuric acid for water is so great, as to enable it to abstract the elements of this liquid from or- ganic substances; in which case they are blackened, and said to be carbonized, in consequence of the evolution of carbon. 50 388 ORGANIC CHEMISTRY. the mixture of sulphuric acid and alcohol, is adequate to keep the temperature sufficiently low, the ether, in the double sulphate, being more volatile than the water, ex- isting in excess in the solution, yields the acid to this li- quid, and comes over, accompanied by a proportional quan- tity of steam, and at the outset, of alcoholic vapour. Thus ether, alcohol, and water, being partially removed, the pro- portion of acid relatively to the residual materials, is in- creased: but as this takes place, its avidity for water aug- ments, and the boiling point of the mixture rises. In consequence of the increased avidity for water, the acid takes from a portion of the ether, C 4 H 5 O, an atom of each of the elements of this liquid, HO. Thus etherine is evolved, C 4 H 4 . 3089. Meanwhile the increased heat causes a portion of the etherine to give up the whole of its hydrogen to a part of the oxygen, of a portion of the acid. Hence sul- phurous acid and carbon are evolved; the one being indi- cated by the carbonaceous colour, the other by its well known suffocating fumes. Under these circumstances, a triple compound, consisting of sulphuric acid and oxide of ethyl, and a portion of undecomposed etherine, being form- ed, comes over with sulphurous acid and ether, forming a yellow liquid. When this liquid is deprived of its sulphu- rous acid by ammonia, or any other alkaline base, and the ether is removed by distillation, the residue is the liquid long known as oil of wine, being the efficient and charac- teristic ingredient of Hoffman's anodyne, erroneously re- presented in several European works as a mere mixture of alcohol and ether. The preferable mode to isolate the oil of wine, is to expose the yellow liquid, in vacuo, over sul- phuric acid in one capsule and slaked lime in another. The sulphurous acid is absorbed by the lime, the ether by the sulphuric acid. The quantity of acid in the oil varies with the mode of isolation; being greatest when the last mentioned mode is resorted to. 3090. The word ether was originally employed to desig- nate a supposed elastic aeriform matter, vastly more rare and subtile than air. It is still used in that sense as an ap- pellation for the matter, which is, according to the undula- tory theory, the medium by which luminous bodies radiate light. By analogy, the word ether was employed to de- signate a liquid which bore the same relation to other OF ACETYL. 389 liquids, as ether proper to air. This appellation has natu- rally been extended to other liquids analogous in proper- ties and composition. Of ethers in general, common ether may be considered as the best exemplification. What mainly distinguishes the liquids thus called, from alcohol, is their very inferior miscibility with water. Many of them are, however, heavier than water, so that, upon the score of density, they do not merit to be distinguished as etherial. 3091. It will be seen that there are several hydrates, formed with other compound radicals, which are congeners of alcohol in composition, and, to a limited extent, resem- ble it in properties. 3092. Generally, substances considered as etherial are susceptible of distillation, are inflammable, little soluble in water, but highly susceptible of union with alcohol, essen- tial oils, and resins. They are, for the most part, fragrant and stimulating to the taste, affecting the animal nerves powerfully when inhaled, or swallowed, even in a minute quantity. OfAcetyl, C 4 H 3 . 3093. The preceding name has been given to a hypo- thetical sub radical containing the same number of atoms of carbon as ethyl, with three atoms of hydrogen instead of five. This radical is inferred to play the same part, in a liquid lately discovered and called aldehyde, that ethyl does in alcohol. In fact, the only difference in composi- tion existing between these liquids, is that between their radicals; the former being produced from the latter by the removal of two atoms of hydrogen. 3094. Acetyl is chiefly interesting as the radical of the important acid of vinegar, designated by modern chemists as acetic acid. This acid, in the hydrated state, in which alone it is capable of isolation, results from the addition of two atoms of oxygen to aldehyde. By the lesser addition of one atom of the same element, another acid has been made, called acetous acid, or aldehydic acid.* * As both this acid and acetic acid have the same radical, the compound, having the lesser proportion of oxygen, should terminate in ous (1052, &c.). Hence the acid in question should be called aldehydous acid, if named, so as to show its deriva- tion from aldehyde, and acetic acid should be called aldehydic acid; but aldehyde itself enters, as an acid, into an ammoniacal compound, the formation of which is a precursory step in obtaining it in a state of purity. Of course, if these compounds 390 ORGANIC CHEMISTRY. 3095. By Liebig, olefiant gas is treated as a hydruret of acetyl, C 4 H 3 + H = C 4 H 4 , which is just double the quantity of carbon and hydrogen contained in a volume of olefiant gas. But, according to Berzelius, the two atoms of carbon, and two atoms of hydrogen, in a volume of this gas, constitute an independent radical, which he calls elayl. Agreeably to Liebig's view, olefiant gas is isomeric with etherine, or etherole, the name given to etherine by him. 3096. Agreeably to the view of the former, the oil re- sulting from the reaction of olefiant gas with chlorine, is a chlorohydrate of chloride of acetyl, C 4 H 3 Cl + HC1, while, if the Berzelian idea be adopted, it consists of two atoms of elayl and two of chlorine, C 4 H 4 Cl 2 . 3097. When this compound is dissolved in a solution of potash and alcohol, it is decomposed into chlorohydric acid, which forms water and chloride of potassium with the potash, and a compound, which escapes in the gaseous form, consisting of C 4 H 3 Cl. The composition of this gas is evidently such, that it may be considered as a chloride of acetyl; and its formation must be regarded as confirm- ing the view taken by Liebig of the composition of the oil of the Dutch chemists. Bromine, like chlorine, on being presented to olefiant gas, produces a compound, which may either be considered as a bromohydrate of the bro- mide of acetyl, or simply as a bromide of elayl, in other words, of olefiant gas; but which, by reaction with the al- kalies, evolves a gas, the composition of which, it would seem, can only be reconciled with the idea of a bromide of acetyl. The action of iodine is analogous, but not so well ascertained. The product is pulverulent in its consistency, but in other respects resembles that which results from the reaction of chlorine with olefiant gas. OfMesityl or Misitylene* C 6 H 4 . 3098. The vapour of pure acetic acid, in passing through a red-hot porcelain tube, is decomposed, yielding a colour- be all considered as oxacids of acetyl, as I think would be more proper, agreeably to the nomenclature adopted in analogous instances, their names would be acetic acid, acetous acid, and hypoacetous acid. But aldehyde, as a congener of alcohol, is, per- haps, preferably designated as a hydrated oxide of acetyl. * Liebig does not introduce this radical into his general list of radicals, but treats of it as a product of the decomposition of acetyl. The same course is pursued in respect to kacodyl, although this contains, as will soon appear, arsenic, an element which does not exist in acetyl. It will also be found that he places sugars under ethyl, as yielding ethyl by their decomposition. This does not appear to me judicious, because, by the same rule that mesityl is placed under acetyl, ethyl should come OF MESITYL. 391 less, limpid, volatile, inflammable, empyreumatic liquid, which has received the name of acetone. This liquid may be obtained, also, by dry distillation, from any dry acetate of an alkali or alkaline earth; also by heating sugar of lead with quicklime, by means of an iron bottle. When acetone is distilled with half its volume of fuming sulphuric acid, upon the liquid which passes into the receiver a yel- low oil swims, which, after being washed with water, is rectified. The first portions contain a little acetone, which is removed by redistillation, by means of a water bath. 3099. This oil is mesityl, being a colourless, oleaginous, inflammable liquid, having a feeble odour, recalling that of garlic. It is lighter than water. With alkalies it under- goes no change. With sulphuric acid, nitric acid, and chlorine, its habitudes resemble those of benzule. Its com- position is equivalent to two atoms of acetone, less two atoms of water. Two atoms of acetone 2C 3 H 3 O = C 6 H 6 O 2 Deduct two atoms of water H 2 O 2 And we have mesityl C 6 H 4 4000. Acetone was inferred to be an hydrated oxide of mesityl; but Dr. Kane, the author of the inference, has admitted that there are not sufficient grounds to justify him in retaining that idea of its composition. Acetone has peculiar and useful powers as a solvent. Many salts \vhich are soluble in both alcohol and water, are insoluble in acetone, especially chloride of calcium and hydrate of potash. It burns with white flame, and has nearly the same density as alcohol. Its taste is disagreeable, having some analogy, however, with that of peppermint. 4001. Metascetone, C 6 H 5 O, is the name given to a co- lourless, volatile, fragrant, inflammable liquid, soluble in al- cohol and ether, but insoluble in water, and which boils at 182.5. It may be considered as two atoms of acetone, minus one atom of water, C 6 H 6 O 2 HO = C 6 H 5 O, me- tascetone. 4002. This liquid is generated simultaneously with ace- tone, when one part of sugar, and eight parts of powdered quick-lime, are subjected to distillation. under sugar. But where a radical only furnishes the elementary ingredients to another compound, or derives its ingredients from one, I do not conceive that any connexion in classification should be made between it and the substances whence it is obtained, or to the formation of which it contributes. 392 ORGANIC CHEMISTRY. 4003. Mesityl forms various compounds with the basa- cigen bodies, which it is not deemed proper to describe here. With sulphuric acid it forms a compound which affords soluble salts with baryta and lime. Reflections on the Relation or Analogy between Acetyl, Ethyl, Amide, and Ammonium. 4004. By the addition of an atom of water, HO, to am- monia, NH 3 , an oxide of ammonium is produced, NH 4 O, which is the base of ammoniacal oxysalts (1116). In like manner it was supposed by Boullay and Dumas, that by the acquisition of an atom of water, etherine, a hydruret of carbon (1267), was enabled to play the part of a base in the neutralization of oxacids. This idea was, for some time, generally sanctioned, and hence, in the last edition of this Compendium, etherine was represented as the base of all the ethers which have, in this edition, been represented as having ethyl as their radical, and its oxide for their base. 4005. It has already been mentioned (1109), that agree- ably to the doctrine advanced by Berzelius, and generally adopted, in the salts formed by presenting ammonia to li- quid acids, the elements of the resulting base exist, not as a hydrate of ammonia, but as an oxide of ammonium. So far as an analogy with the habitudes of ammoniacal com- pounds would influence the view adopted, a corresponding conception would be created, that in etherial compounds the base should be an oxide of ethyl, not a hydrate of etherine. Besides the correspondence thus existing, there was no small analogy between the relation borne by amide to ammonium, and acetyl to ethyl : the only discordancy being, that the susceptibility of forming acids, displayed by acetyl, has not been observed in amide. Of the Compound Hypothetical Radical, Kacodyl, C 4 H 6 AS, Symbol Kd. 4006. The substance to which the name above men- tioned has been given, is one of the many compound radi- cals of which the existence has lately been inferred by chemists. It has the unusual feature of containing, among its essential constituents, an atom of a metallic radical, arsenic. Its name is from **$, bad, and *Jx odour. 4007. The protoxide of kacodyl constitutes a fetid, viru- lently poisonous, etherial, spontaneously inflammable, vola- OF KACODYL 393 tile, limpid liquid, long known as the fuming liquor of Cadet, its discoverer. This liquid, now called alcarsin, is obtained by distilling dry acetate of potash with an equal weight of arsenious acid. By digesting alcarsin, or oxide of kaco- dyl, in chlorohydric acid, chlorine taking the place of oxy- gen, a chloride of kacodyl results. From this the radical is separated, by reaction with metallic zinc, at the tempe- rature of 230, and removing the resulting chloride of zinc by water. 4008. Kacodyl is an etherial, limpid, spontaneously in- flammable liquid having a nauseous odour. It sinks in water without dissolving, but is soluble in alcohol or ether. It boils at 338. At a red-heat its vapour is resolvable into arsenic, olefiant gas, and light carburetted hydrogen. 4009. The following compounds are formed by this ra- dical, of which it does not appear consistent to treat par- ticularly here. Kd O Alcarsin Oxide KdCl Chlorarsin Chloride Kd S Sulpharsin Sulphide Kd Cy Cynarsin Cyanide Kd O 3 + HO Alcargen Hydrated trioxide of kacodyl. 4010. Agreeably to the preceding formulae of the com- pounds of kacodyl, it may be seen that, excepting alcar- gen, they differ, in composition, only as respects one of their ingredients, a basacigen element, to the presence of which they owe the diversity of the names given in one of the lists. 4011. Alcargen, or kacodylic acid, differs from the rest in holding an atom of water, HO. 4012. Liebig supposed the bodies in question each to consist of an atom of acetyl and an atom of arsenuretted hydrogen, As H 3 , not grouped into one radical; but Ber- zelius suggested that they were so grouped, and this Bun- sen has proved to be true, by isolating kacodyl as above described. 4013. It may, however, be well to point out, that the composition of kacodyl is consistent with the idea of Lie- big, since an atom of acetyl, - C 4 H 3 and an atom of arsenuretted hydrogen, As H 3 are equivalent to an atom of kacodyl, C 4 H 6 As 394 ORGANIC CHEMISTRY. 4014. I object to the unmeaning names above given, as not conveying any idea of composition. Hence I shall use those which indicate the composition. 4015. Alcargen, more significantly called kacodylic acid, or hydrated trioxide, agreeably to the nomenclature which would make hydrous sulphuric acid a sulphate of water, would be a kacodylate of water. Of Methyl, C 2 H 3 . 4016. After it had become evident that the etherial com- pounds, derived from the reaction of alcohol with acids or halogen bodies, had all a common compound radical, che- mists were naturally led to infer, that there might be other series, similar in their nature, having the same electro- negative ingredients united with other compound radicals. These speculative inferences first received a practical verification, from the labours of Dumas and Peligot re- specting the composition and combinations of pyroxilic spirit, obtained from the products of the destructive distil- lation of wood or other organic products. From the in- vestigations of these chemists it has been made evident, that pyroxilic spirit is the alcohol of a series of compounds having methyl as a radical. 4017. The compounds of methyl with the basacigen class, and those formed between its oxide and acids, are produced by reactions with methylic alcohol or ether, or their products, similar to those by which analogous com- pounds with ethyl are effected. There is, likewise, a great analogy in the properties of the two series; yet methylic ether (or in other words the oxide of methyl the com- pound which is the congener of ether proper), is gaseous, in lieu of existing like ether as a liquid. Moreover, a ni- trated oxide of methyl, or a true methylic nitric ether, is readily generated when wood spirit (hydrated oxide of me- thyl), is presented to nitric acid. This etherial compound, has no congener among those of ethyl, because the reac- tion, between nitric acid and alcohol, is attended by a reciprocal decomposition, by which hyponitrous acid is evolved and combines, while nascent, with oxide of ethyl, existing in an undecomposed portion of the alcohol. Hence it arises, that hyponitrous ether is generated in- stead of nitrated oxide of ethyl. On the other hand no hyponitrite of the oxide of methyl, results from the reac- OF FORMYL. 395 tion of nitric acid with wood spirit ; since the decompo- sition, requisite to the development of hyponitrous acid, does not ensue. Consequently, Liebig alleges that no con- gener of hyponitrous ether exists among the etherial com- pounds of methyl. 4018. I have recently been enabled to fill up this inter- val in the methyl series, by subjecting wood spirit to a hy- ponitrite, in contact with a diluted acid. Of Formyl. 4019. Formyl has a relation to methyl, similar to that which acetyl has to ethyl. In either case, there is a radi- cal differing from another, only by the subtraction of two atoms of hydrogen. 4020. The hydrated oxide of formyl is inferred to exist in a liquid, obtained by the reaction of two parts of wood spirit with three of sulphuric acid, three of water, and two parts of peroxide of manganese. An inflammable, etherial, colourless liquid, of an agreeable aromatic odour and sus- ceptible of solution in three parts of water, was thus pro- cured. This liquid has been inferred to be a compound of two atoms of oxide of methyl, and one of hydrated ox- ide of formyl. 4021. There are in the formyl series no compounds corresponding to aldehyde, or acetous acid. The only oxide is that long known as formic acid, from its having been first obtained from ants. This acid is obtained from formyl, as acetic acid from acetyl, by the addition of three atoms of oxygen. 4022. Agreeably to Liebig, three chlorides of formyl have been isolated. The perchloride has been known for a good while, having been obtained by distilling alcohol with hypochlorite of lime. It was obtained about ten years since in this country by Gurthrie, and for some time confounded with the etherial oil of olefiant gas, which is now considered by Liebig as the chlorohydrate of the chloride of acetyl. Amyl, C 10 H 11 . 4023. A peculiar liquid was noticed by Scheele to ac- company potato spirit. Subsequently, by Pelletier, Ca- hours and Dumas, it was inferred to be the hydrated oxide of a peculiar compound radical, to which the name at the 51 396 ORGANIC CHEMISTRY. head of this article was given. It follows that this liquid must be a congener of alcohol, its formula being C 10 H 11 + HO. 4024. The amyl series of compounds corresponds with those of other radicals to a certain extent, but is upon the whole very incomplete, having no oxide to occupy the place of a congener of ether. Even the chloride does not appear to be permanent per se. The bromide and iodide are more enduring, and in their habitudes somewhat analogous to corresponding combinations in the series of other radicals. 4025. Yet in the case of sulphoamylic acid, the ana- logy is well supported to other etherial double sulphates, such as sulphovinic acid, and there have been formed sul- phoamylates capable of decomposition and of reproducing the hydrated oxide, potato spirit. 4026. An amylic acetic ether has been produced, by distilling two parts of acetate of potash, one part of potato spirit, and one part of sulphuric acid. As respects in- flammability, volatility and insusceptibility of mixture with water, the amylo acetic ether is truly etherial in its nature. 4027. By the substitution of two atoms of oxygen for a like number of hydrogen, effected by treating potato spirit with hydrate of potash, a change in composition arises analogous to that by which alcohol is converted into acetic acid. An acid is in this way created, called valerianic, in consequence of its being identical in properties and com- position with that extricated by distilling water from the root of valerian. 4028. This acid was produced, also, by causing potato spirit to fall slowly in successive drops upon platinum black duly heated. Peculiar liquids, somewhat etherial in their properties, have been evolved from potato spirit, of which the one C 20 H 17 Cl 3 O 2 seems to be a congener with chloral, the other with olefiant gas the hydruret of carbon of Liebig. Glyceryl, C 6 H 7 . 4029. The wonderful fabric of scientific knowledge for which we are indebted to the skill, sagacity and ingenuity of modern chemists, is formed in part of materials which are altogether new, and in part of such, as although long known, owe nearly all their present theoretic value to the OF GLYCERINE. 397 part which they have latterly been made to answer in the great fabric to which I have alluded. 4030. In the preceding account of the amyl series it may be noticed, that a liquid long since distinguished by Scheele, and known under the name of oil of potato spirit or oil of potatoes, has latterly been dignified with a place among the congeners of alcohol. 4031. In glycerine, C 6 H 7 O 5 + HO, the hydrated oxide of the compound radical glyceryl, we find, in like manner, a compound of similar antiquity, and, as respects its dis- coverer, of like origin ; having been well known since the time of Scheele, as the sweet principle of oils. For the rank which it now occupies, the scientific world is indebted to Chevreul and Pelouze. 4032. Anterior to the labours of Chevreul, an erroneous notion existed that the process of saponification consisted in nothing more than a union between the alkali and oil; so that it was deemed to be a case simply of combination. The existence in every oil of an electro-negative, and an electro-positive ingredient, the one performing the part of a base, the other of an acid, was not imagined. 4033. The oxide of glyceryl is the base common to a majority of vegetable and animal fixed oils, whether liquid or the solid state, denominated fat, being liberated during the boiling of those substances with fixed alkalies, as in the process of saponification. It is best prepared by sapo- nifying oil of olives with litharge, separating the resulting solution of glycerine, and precipitating any dissolved lead by sulphydric acid (897, 899). 4034. Glycerine is said to be deficient of two properties belonging to its alcoholic congeners, solubility in ether, and susceptibility of distillation without decomposition. It is sweet, colourless, and inflammable; of the density of 1.252, being about one-fourth heavier than water. 4035. It does not appear that there are any other im- portant compounds formed with this radical by the basaci- gen bodies or the acids, so as to be productive of com- pounds congeneric with those so formed by most of the other etherefiable compound radicals. There is, neverthe- less, a congener of sulphovinic acid in sulphoglyceric acid, more properly called the double sulphate of the oxides of glyceryl, and of hydrogen. 398 ORGANIC CHEMISTRY. Cetyl, C 32 H 33 . 4036. Of cetyl it may be sufficient to say, that it is per- fectly analogous as respects the part which it performs in spermaceti, with that performed by glyceryl, as the radi- cal in the base of the fixed oils generally. 4037. The diversity of such oils, in other cases, is pro- duced by variation in the acids with which the oxide of glyceryl in them severally is combined. Spermaceti has been represented as a solitary instance in which a change of properties results in a concrete fixed oil, from a pecu- liarity in the hydrated oxide constituting the base, while the acids, combined with this base, are those which have been described as entering into the composition of oleagi- nous products in general. Recently, this view of the sub- ject has been controverted by Smith. Silliman's Journal, October, 1842. (See 5055, page 426.) 4038. The hydrated oxide of cetyl, C 32 H 33 O + HO, may be elaborated from spermaceti by saponification, in a mode resembling that by which glycerine is obtained. It has been designated by the name ethal, a word made up of the initials of alcohol and ether. It differs from other alco- holic hydrated oxides, in being deficient of that solubility in water which is one of the most striking and distinguish- ing attributes of alcohol proper. It differs also in being solid until heated to 118. The analogy with glycerine fails as respects taste, being insipid; also in this, that gly- cerine is soluble in water, and insoluble in ether. 4039. Cetyl has not been isolated; but by repeated dis- tillation with anhydrous phosphoric acid, ethal has been made to yield an inflammable liquid compound, C 32 H 32 , having to it a relation analogous to that which etherine or etherole, C 4 H 4 , has to ethyl, C 4 H 5 . Cetene, as this liquid is called, seems to be of the nature of an essential oil, since it may be distilled. It requires, however, the high tempe- rature of 527 for this purpose. 4040. Cetyl coincides in habitudes with the other com- pound radicals of this class, as respects the formation of double sulphates, analogous to the sulphovinates. It also forms a chloride capable of being distilled, and by the sub- stitution of three atoms of oxygen for two of hydrogen, is converted into an acid, denominated ethalic, C 32 H 31 O 3 , which is a congener of acetic acid. OF GUM. 399 OF NUTRITIOUS VEGETABLE SUBSTANCES DEVOID OF NITROGEN. 4041. Under this head I place gum, sugar, fecula, and lignin. Immediately, this last mentioned substance is rather food for worms than for man; but it will be seen that lig- nin may be converted into sugar. 4042. The substances above enumerated might be treat- ed as hydrates of carbon, agreeably to the suggestion of Prout (2096), were it not that their properties do not war- rant the idea, that the hydrogen and oxygen are more in- timately allied to each other, than to the carbon. Of Gum. 4043. Substances known under the generic name at the head of this article have certain properties in common, but vary with the tree by which they are generated. Some, like gum arabic, or gum Senegal, are perfectly soluble in water; while others, like tragacanth, are capable only of forming a paste with the same liquid. Those of the first mentioned kind are susceptible of rapid desiccation and induration, by access of atmospheric air, while the others give up water, comparatively, with reluctance. They are all distinguished from resins, which they resemble exter- nally, in being insoluble in alcohol, ether, or essential oils. They differ from sugar in the want of sweetness, and from starch in not being coagulable by heat. 4044. Guerin, in an elaborate treatise on gums, divides them into three classes: 1. Arabin, of which gum arabic is the type, soluble in cold water. 2. Bassorin, which swells into a jelly, but does not dissolve in water: gum bassora, or tragacanth, may exemplify this class. 3. Ce- rasin, from the gum of the cherry-tree. Cerasin is also insoluble in cold, but soluble in boiling water, and when treated with nitric acid, gives about one-fourth less mucic acid than bassorin. 4045. Of arabin, by his analysis, the formula is C 6 H 5 O 5 . Gum Senegal, and the soluble parts of gum tragacanth and bassora gum, consist of arabin. 4046. Of bassorin the formula is C 10 H 11 O 11 . 4047. Cerasin appears to be metamorphic arabin; for it has precisely the same composition, and is changed into it by solution in boiling water. The gums of the cherry, apricot, prune, peach, and almond tree, are of this kind. 400 ORGANIC CHEMISTRY. 4048. Berzelius employs the word mucilage to desig- nate that species of matter which is exemplified by the bassorin of Guerin. Varieties of this kind of gum are seen in infusions of flaxseed, of slippery elm, and pith of sassafras. This use of these terms is not adopted by Tur- ner, Kane, or Graham. The principal difference between gum and mucilage, agreeably to general acceptation, seems to be, that mucilage is not susceptible of spontaneous har- dening by desiccation. Graham admits only of two genera of gums, exemplified by gum arabic and gum tragacanth. By Kane, they are treated of under three heads arabin, cerasin, and dextrine, or artificial gum. This last men- tioned variety is obtained from starch, and does not ap- pear to have higher pretensions to be ranked as a gum, than the modification of starch by heat, known as British gum. Substances which come under the name of gum, agree in general properties ; yet there are scarcely any two which are quite similar. Gum arabic is deemed to be the most perfect specimen of the substances bearing this name. 4049. Berzelius considers the reaction of a solution of this substance with a solution of the silicate of potash, as the most striking characteristic of its properties. One portion of it forms, with one part of the alkali and all the acid, a triple compound, which precipitates ; while another portion of the gum, and the remainder of the potash, com- bine and remain in solution. 4050. Gum arabic differs from other gums in combining with the sesquioxide of iron, and forming a compound in- soluble in water, but soluble in acids. A solution of gum arabic in 1000 parts of water, being mixed with a solution of the sesquioxide of iron, yields, in 24 hours, a yellow precipitate. This species of gum also combines with, and precipitates the protoxide of mercury from the nitrate. There appears to be no important difference between gum Senegal and gum arabic. Of Sugars* 4051. Under this head I would place two genera of sub- stances; crystallizable sugars, and syrups incapable of * Liebig treats of sugars under the general head of an " appendix to the combina- tions of ethyl and acetyl." His commentator, Gregory, alleges that they are "thus treated of, since from them are derived all the compounds of ethyl; and, also, be- OF SUGARS. 401 crystallization, and which might be called suavin. Of the former, sugar candy, and the crystals found in raisins and honey, are specimens. The latter are exemplified by the uncrystallizable syrups of raisins and of honey; also the sweet matter of the sweet potato, and the uncrystallizable syrup of the sugar cane, known as molasses. 4052. The qualities, both of crystallizable and uncrys- tallizable sugars, vary with the plants from which they are produced. In the power of imparting sweetness to infusions, the crystallizable sugar of the cane is pre-emi- nent. 4053. As sugar has been found to be very susceptible of yielding alcohol by fermentation, this property has been made the basis of defining the meaning of the word, so that every substance capable of the process alluded to, is to be considered as sugar, whatever may be its taste, or however it may differ in its properties from the substances usually called by the name. 4054. Thus the fermentable "wort" of distillers or brewers, the uncrystallizable juices of fruits, a substance found in mushrooms or ergot, also an insipid matter found by Thenard in diabetic urine, are all to be considered as consisting of sugar, so far as they are capable of yielding alcohol by fermentation. 4055. I am reluctant to employ words in a sense dif- ferent from that in which they are generally understood. Agreeably to usual acceptation, sweetness is an indispen- sable attribute of sugar. Sugary and sweet are synony- mous. " As sweet as sugar" has long been an expression conveying the idea of superlative sweetness. 4056. Chemists have erred, I think, in assuming that cause the uncertainty in which we are as to their true constitution, renders it im- possible to arrange them on scientific principles." That ethyl compounds are derived from sugars, might be a reason for treating of them under sugars ; but I cannot perceive the converse to be true. But as aldehy- dous or acetous acid, and acetic acid, are placed under the head of acetyl, and the compounds of mesityl are derived from acetic acid, a compound not necessarily de- rived from sugar, if the reason above given were sufficient for placing sugars under ethyl, it is, on that same ground, improper to place them under acetyl, since this ra- dical is not necessarily a product of sugar. In reply to the last sentence quoted, it might be demanded, why inability to ar- range sugars upon scientific principles, justifies their being placed under the head selected, in preference to any other: whether every set of substances which cannot be arranged on scientific principles, are to be discussed under the joint head of com- binations of ethyl and acetyl? The best justification which occurs to me for any connexion between cane sugar and acetyl is, that when anhydrous it is isomeric with acetyl, one atom containing three of this radical, acetyl, & R* -f- 3 =s C H O^. 402 ORGANIC CHEMISTRY. nothing besides sugar is susceptible of the vinous fermen- tation. The conversion into alcohol of the insipid product of diabetes, which has been treated as sugar, because proved to be susceptible of the process in question, might with more propriety, as I conceive, be deemed to demon- strate that this process may be undergone by substances which are not sufficiently of a saccharine nature to merit the name of sugar. 4057. According to Kane, after cane sugar has been subjected to a ferment, at a certain time before its conver- sion into alcohol, it affects polarized light in the same way as grape sugar. Hence it is inferred, that cane sugar is not directly susceptible of the vinous fermentation; and that of all sugars, that of the grape only is capable of immediately undergoing that process. It follows, that if the contested definition be not disregarded, the sweet crystallizable matter extracted from the cane, hitherto considered as the most perfect of the sugars, must be de- prived of its title, and occupy a place on a level with starch, as being, like this substance, incapable of the vi- nous fermentation, without a previous transformation into grape sugar. 4058. Liebig enumerates the following varieties of su- gar. Cane sugar* grape sugar, lactin or sugar of milk, un- crystallizable sugar, and sugar of mushrooms. To these Graham adds, insipid diabetic sugar, manna sugar or man- nite, and liquorice. 4059. As a good account of the sources of the sugar of commerce, and the means by which it is elaborated may be found in the United States' Dispensatory, it will be doubly inexpedient to extend in this treatise the informa- tion given, beyond its chemical composition and habitudes. 4060. Of cane sugar, perfect specimens are seen in the best double refined sugar, and in colourless sugar candy. Its specific gravity is 1.6. At 350 it fuses into the well known form of barley sugar, which, by exposure to air, is alleged to become white, opaque, and crystalline. 4061. Exposed to the temperature of 650, by losiirg an atom of water besides that of crystallization, sugar is transformed into the dark brown substance called caramel. Thus obtained, caramel is not entirely exempt from unde- composed sugar and other impurities, but may be freed from them by solution in water, and precipitation by alco- OF GRAPE SUGAR. 403 hoL The precipitate thus created, when dried, forms a black or dark brown powder, which may be redissolved in water. It is insipid, not fermentable, and neither acid nor alkaline. Caramel is used to deepen the colour of fer- mented or spirituous liquors. During its decomposition by heat, fumes are emitted by sugar, which not only dis- guise, but, as I believe, neutralize fetid emanations. For its solution, cane sugar requires one-third of its weight of cold water, but the effect of this liquid at a high tempera- ture, is rather that of lowering the point of fusion, than acting as a solvent; since, at the temperature of 350, su- gar liquefies per se, and of course may liquefy with the mi- nutest proportion of water which can be added. Hence the liquefaction is due to heat rather than to water. 4062. If a concentrated solution of sugar be subjected, for some time, to the temperature requisite to vaporize the excess of water, under the whole pressure of the atmos- phere, it is changed by degrees into uncrystallizable sugar. Hence, of late years, the vaporization is aided by a reduc- tion of atmospheric pressure, by means of an air pump. (172.) 4063. Sugar combines with some salts; and acts feebly as an acid, so far as to unite with some bases. In the insoluble compound, formed by anhydrous sugar with oxi- dized lead, the base is a dioxide. With one atom of ba- ryta, sugar forms a crystalline compound; with common salt it forms crystals readily soluble in water. 4064. Berzelius alleges that an aqueous solution of su- gar dissolves the carbonate and subacetate of copper, giving rise to a green liquid, from which the metal is pre- cipitated by sulphydric acid, or cyanoferrite of potassium, but not by alkalies. When boiled with solutions of cu- preous salts, it causes the reduction of the copper. 4065. Several products are obtained by the reaction of various acids, either dilute or concentrated, with the various kinds of sugar; also by their reaction with alkalies. These products being complicated in their nature and of little practical utility, I shall not treat of them here. Grape Sugar. Crystallized, C 12 H 14 O 14 ; Anhydrous, C M H 12 O 12 . 4066. Crystals of this sugar may be seen in raisins, in what are called candied sweetmeats, and in honey, in either 52 404 ORGANIC CHEMISTRY. of which it forms the least fluid portion. Fruits generally owe their sweetness to its presence. The sugar formed from starch by digestion with diastase, or sulphuric acid, is of this species; and also the sugar of diabetes.* 4067. Grape sugar may be obtained in crystals from grape juice, by neutralization with chalk, clarifying with albumen, evaporation, and subsequent repose: also from diabetic urine, by evaporation to dryness, by means of a water bath, washing the resulting crystalline mass on a filter with cold alcohol until it becomes white, and repeated re-solution and recrystallization. 4068. It is remarkable, that notwithstanding the ana- logy between cane and grape sugar, they differ much in their chemical qualities, as shown by their habitudes with chemical reagents. Strong mineral acids, which react but feebly with grape sugar^ readily decompose cane su- gar. With alkalies an opposite result ensues. The com- pounds which are formed by these sugars respectively, with bases, are quite different. 4069. From an alcoholic solution, grape sugar crystal- lizes in transparent square tables or cubes; from an aque- ous solution, it consolidates into a spongy mass of crys- talline grains.t Sugar of Milk, or Lactin. 4070. The formula of crystallized sugar of milk is C 24 H 24 O 24 , or C 24 H 19 O 19 + 5HO. By a heat of 248 it loses two atoms of water, and by 302, five atoms. (Berzelius.) It is obtained by evaporating the whey of milk, and puri- fying the first crystalline product by animal charcoal and recrystallization. It forms white, semi-transparent, quad- rangular prisms, which have the density 1.543. They are soluble in five or six parts of cold water, and in two and a half parts of boiling water. The taste of the crystals is very feeble, being inferior, in sweetness, to that of their solution. Sugar of milk is unalterable in the air, or by a heat under 212, and is insoluble in alcohol or ether. When milk is exposed to a temperature of from 95 to * Dumas has proposed that grape sugar be called glucose; but as Liebig alleges that all sugars, even that of the cane, have to be converted into grape sugar in order to be rendered susceptible of the vinous fermentation; it would seem, consistently with the received definition of sugar (4053), as if cane sugar should be called glu- cose, yielding the name of sugar to the sweet matter of the grape. t See fermentation; also (4071). OF MUSHROOM SUGAR, &C. 405 104, it undergoes the vinous fermentation, generating al- cohol, while its sugar disappears. But it is presumed that the latter is converted first into grape sugar, probably under the influence of the free acid, which, being formed, curdles the milk. Milk sugar forms two compounds with oxide of lead, of which the formulae are C 24 H 19 O 19 + 5PbO, and C 24 H 19 O 19 + lOPbO. (Berzelius.) Mushroom Sugar. 4071. This sugar, of which the formula is C J2 H 13 O 13 , according to an analysis by MM. Liebig and Pelouze, was obtained by M. Wiggers, by subjecting the tincture of the ergot of rye to water. It is crystallizable and solu- ble in water and alcohol, but insoluble in ether. Mush- room sugar is also fermentable by yeast, and diffuses the odour of caramel when carbonized by a high temperature. The only property by which this sugar is distinguished from the ordinary species is, that it does not throw down sub-oxide of copper from a boiling solution of the acetate. Of the Fermentable Matter of Diabetes, called Insipid Sugar. 4072. It has been stated (4052), that a substance was obtained, by Thenard, from the urine of diabetes insipidus, and, subsequently, by Bouchardat, from the same source, which was insipid, or only faintly sweet. The aqueous solution of this sugar was fermentable by yeast, and sus- ceptible of being converted into the sugar of grapes by di- lute sulphuric acid. Liquorice Sugar. 4073. The inspissated juice of the root of the Glycyr- rhiza glabra contains a species of unfermentable sugar, which may be obtained by clarifying the juice with albu- men, precipitating the sugar with sulphuric acid, washing the precipitate with water, dissolving it in alcohol, which separates some undissolved albumen, and then decom- posing the sulphate of liquorice sugar by carbonate of pot- ash. After evaporation, the sugar remains as a yellow translucent mass, cracked in all directions, and easily de- tached from the vessel in which it has been desiccated. Liquorice sugar is capable of forming soluble or sparingly soluble compounds, with both the mineral and vegetable acids. It also combines with bases. 406 ORGANIC CHEMISTRY. Manna Sugar, or Mannite. 4074. The formula of manna sugar is C 6 H 7 O 6 , accord- ing to the analysis of Oppermann and of Liebig. Manna is in oblong globules or masses, of a yellowish-white co- lour, being an exudation from various trees, principally the fraxinus ornus, and encalyptus mannifera of New South Wales. It exists also in the juices exuded by cherry and plum trees, in those of various kinds of mushrooms, and of celery and other roots. Manna sugar may be prepared by dissolving the manna of the shops in boiling alcohol, and allowing the solution to cool. It may be purified by repeated crystallizations. Mannite crystallizes in slender, colourless, four-sided prisms, of an oily lustre. It has a slightly sweet taste, forms, with water, a solution which is not fermentable. It is anhydrous, and may consequently be heated to redness, without any loss of weight. Its aqueous solution dissolves oxide of lead. Nitric acid con- verts mannite either into oxalic, or saccharic acid; but not into mucic acid. Mannite is also one of the products of the vinous fermentation of cane, or grape sugar. 1 * Fecula, or Starch. 4075. A substance, of which starch is a good specimen, and of which the generic name is fecula, may be obtained from the rneal or flour of grain, and from the tubers of the potato, and various other vegetables. It is found in com- merce under the names of sago, tapioca, arrow-root, &c. Of the sources of these varieties of fecula, an excellent ac- count is given in the United States Dispensatory. It is more or less a constituent of vegetables in general. When the farinaceous matter, procured from such sources by rasping or grinding, is washed, the fecula is suspended, and subsequently deposited. Where there is vegeto-animal matter, as in wheat flour, fermentation is employed to get rid of this substance. 4076. It was discovered by Leeuwenhoeck, with the aid of a microscope, in 1716, that starch consists of globular trains, each enveloped in a tegument, pocket, or sac, dif- jring from the internal mass. In 1825, these observa- tions were confirmed and extended by Raspail, who also * Graham, page 757. OF DIASTASE. 407 observed that the envelope, or tegument, was insoluble in water, while the interior portion was soluble in this liquid. Agreeably to the microscopic observations of this last mentioned author, the sizes of the globules of fecula vary with the plant whence it may be derived. Those of the potato did not exceed in diameter ws of an inch; those of wheat 2T7 of an inch; and of arrow-root TGV. As, accord- ing to Payen and Persoz, the tegument does not form more than four or five thousandths of the weight, the internal portion may be considered as characterizing the whole, uninfluenced to any important extent by the tegumentary matter. 4077. Fecula is blackened by a certain quantity of io- dine, becomes blue with less, and violet with still less. The iodide of starch becomes colourless at a temperature less than 200, and if not made to reach the boiling point, regains its colour on cooling. 4078. Starch does not combine with cold water, but forms a viscid solution with hot water. It is neither dis- solved nor acted upon by alcohol or ether. 4079. Fecula dissolves in nitric acid without heat, and when heated with it is converted into oxalic acid. A slight torrefaction changes its nature, so that it may be used as a substitute for gum. Triturated with potash, fecula ac- quires the property of dissolving in cold water. The so- lution is clouded by acids. 4080. Its solution in hot water is precipitated by sub- salts of lead, and in cold water by an infusion of galls. s OF DIASTASE, And of the Conversion of Fecula into Dextrine and Grape Sugar. 4081. Boiled in water, constantly replenished for nearly forty hours, with between T V and T ihr of its weight of sul- phuric acid, fecula is converted into grape sugar. A simi- lar change is alleged to have ensued partially in starch, which was made into a paste with twelve times its weight of boiling water, and kept for two years. By the addition of the glutinous matter obtained by washing wheat dough, and the application of a heat between 122 and 167 Fah., a similar result is said to have been attained in about ten or twelve hours. 408 ORGANIC CHEMISTRY. 4082. It is well known to those who are acquainted with the manufacture of whiskey from grain, that a portion of malt is necessary to render the wash or wort susceptible of the vinous fermentation; and that the product is much affected by the circumstances under which the infusion of the grain is accomplished. Nearly thirty years ago, my late friend, Col. Anderson, who had distinguished himself by his ingenuity and sagacity in improving the processes and apparatus of our American distilleries, expressed to me an opinion, that the mixture of farina and water be- came sweeter towards the close of the process of infusion, and that he believed a chemical change was induced, by which more or less sugar was generated. The inference of our ingenious countryman has been fully justified by the researches of Payen and Persoz, whence it appears that, by digestion with malt, fecula is at first partially changed into a sweetish gummy matter, called dextrine, and that this matter is afterwards converted into grape sugar. Dextrine has received its name from a peculiar influence which it exercises upon the plane of polarization, during the passage of light.* It may be considered as holding, as respects its properties, an intermediate position between fecula and grape sugar. 4083. The sugar-producing property thus existing in malt, has been traced to a peculiar principle called dias- tase, which exists therein in a proportion not exceeding a five-hundredth. It is obtained by moistening ground malt with half its weight of water, and exposing the mass to pressure. The exuding liquor is mingled with a quantity of alcohol of 840, by which the diastase is thrown down impure. By three successive solutions in water, and pre- cipitations by the same means, with subsequent exposure on a glass pane, in thin layers, to a current of air about * When light, polarized by reflection from the surface of a plate of black glass, or from the surm.ce of a pile of superposed plates of transparent glass, reaches the eye through a disc of tourmalin, a solution of dextrin being interposed in a tube between the reflecting plate and tourmalin, the light does not disappear in those positions of the tourmalin in which light would be completely absorbed without the interposition of the solution of dextrine ; but prismatic colours are produced which follow a certain order, if the plane of polarization is turned from left to right. It is by the order of these colours, that a liquid is said to polarize light to the right or to the left. The solution of starch polarizes to the right, and that of dextrine considerably more so in the same direction ; while a solution of cane sugar produces the succession of colours in an inverse order, and is said therefore to polarize to the left. The progress of chemical changes may thus often be observed in a solution of starch, the juices of plants, and other organic fluids. Graham, 743. OF LIGNIN. 409 121 Fah., pure and dry diastase is obtained in the state of a white amorphous solid matter. Diastase does not alter gum, sugar, gluten, nor albumen, nor the teguments of fecula, but operates surprisingly, as above described, on fecula proper. This change is effected without any ab- sorption of the air, or any evolution of gaseous matter. It may take place either in pleno or vacuo. An infusion of 100 parts of starch in 39 parts of water, at about 90 Fah., being mixed with 6.13 parts of diastase, dissolved in 40 parts of cold water, and digested afterwards for an hour, at a temperature between 90 and 100, gave 86.91 parts of sugar. At the temperature of 158, one part of dias- tase will convert 2000 parts of starch into sugar.* 4084. When sulphuric acid is employed in lieu of dias- tase, if, by confinement, the temperature and pressure are raised (192), less sulphuric acid will suffice. Less time is requisite when care is taken to prevent too rapid refrige- ration. 4085. If a paste, made by subjecting starch and water to ebullition, be gently poured into a boiling dilute solution of sulphuric acid, the pasty consistency soon disappears. In like manner, starch paste loses its gelatinous character when mingled with malt wort, and if kept at a temperature between 190 and 200, becomes, at the end of some hours, converted into grape sugar. 4086. In proportion as the diastase saccharifies the starch, it disappears itself; and when the solution no longer acts on a fresh portion of starch, the presence of diastase cannot be detected in it. The reaction is proba- bly chemico-electric, and if understood, would throw light on a multitude of phenomena. 4087. When dried, diastase is a white, solid, amorphous substance, soluble in water and in weak alcohol, but in- soluble in absolute alcohol. It is not known to enter into combination with any substance.t It received its name from JWjj^,, I separate, in reference to separation of the envelope of the starch globules (4065). Lignin. 4088. The tasteless, inodorous, insoluble, but tenacious fibres of wood, hemp, cotton, or flax, and other plants, * Graham, 745. Annales de Chimie et de Physique, Vol. 53, p. 73. t Gregory's Turner, 943. Graham, 744. 410 ORGANIC CHEMISTRY. have been deemed to consist of a peculiar vegetable sub- stance, called lignin, from lignum, the latin for wood. The formula of lignin, dried between 300 and 350, is C 12 H 8 O 8 (Prout). 4089. Graham alleges, that it constitutes about 95 per cent, of baked wood, and that it may be obtained in purity by treating the sawings of wood, paper, or the fibre of lint, cotton, hemp, &c., successively with ether, alcohol, water, diluted acid, and a caustic alkaline solution, so as to dis- solve and remove all the matter soluble in those menstruse. Wood consists of an association of capillary tubes, in which, after it is desiccated, agreeably to the observations of Hartig, a quantity of starch remains, in spherical grains of a grey colour. Hence by triturating it, in the state of fine saw-dust, with water, from one-fourth to one-fifth of its weight of starch may be obtained. 4090. If Payen is to be credited, wood consists of two organic principles, one of which is isomeric with starch, having the same formula, C 12 H 10 O 10 , being named cellu- lose by him. The other principle, which forms the tubes, is considered by the same author as the true lignin. Cellu- lose was obtained by subjecting sawings of beech wood to several times its weight of the most concentrated nitric acid, which leaves that principle, while it dissolves the lig- nin. Cellulose is dissolved by concentrated sulphuric acid without blackening, and is then converted into dextrine. The formula of lint, hemp, straw, and linen cloth, was found by Payen to be C 35 H 24 O 20 . Oak wood, by the ana- lysis of Gay-Lussac and Thenard, is C 36 H 22 O 22 . 4091. When hemp, straw, &c., are added cautiously to concentrated sulphuric acid, so as to prevent elevation of temperature, not only is dextrine created, but also ligno- sulphuric acid, analogous to benzo-sulphuric acid, which forms a soluble salt with baryta, or with oxide of lead. 4092. The dextrine formed when lignin is dissolved in sulphuric acid, is converted, by dilution and boiling, into starch sugar. 4093. Saw-dust, gum, and starch, dissolve in the most highly concentrated nitric acid, without decomposing the acid ; and, if immediately diluted with water, give a white pulverulent neutral substance, insoluble in water, which contains the elements of nitric acid, and is highly combus- tible. OF VEGETO- ANIMAL SUBSTANCES. 411 4094. To obtain grape sugar from lignin, twelve parts of shreds of paper or linen, or of wood shavings, are inti- mately incorporated by trituration with seventeen parts of concentrated sulphuric acid (according to Vogel five parts), and one of water, carefully preventing any rise of temperature. After twenty-four hours, the resulting tarry mass is to be dissolved in water, boiled for ten hours, neu- tralized with chalk, and being filtered and evaporated to a syrupy consistence, the residue is to be left to crystallize. 4095. According to Brunner, 100 parts of fecula yield 100 of crystallized grape sugar; according to De Saussure, 110. Agreeably to calculation, 100 of fecula, with four atoms of water, should be productive of 120 of sugar. 100 parts of linen shreds produce 114 of sugar, according to Bracconot; or, according to Guerin, 115 parts'. 4096. lit is worthy of remark, that the formula of crys- tallized grape sugar may be made by adding to the for- mula of lignin six atoms of water; to that of starch, four atoms; to that of cane sugar, three atoms; and to that of sugar of milk, two atoms. Formula of lignin, C 12 H 8 O 8 Starch, C 13 H 10 O to Six atoms of water, H 6 O 6 Four atoms of water, H 4 O * Crystallized grape sugar, C 13 H 14 O 14 Grape sugar, C ia H 14 O 14 Crystallized cane sugar, C 13 H 11 O 11 Sugar of milk, C 13 H 13 O 12 Three atoms of water, H 3 O 3 Two atoms of water, H 3 O a Grape sugar, C 13 H 14 O 14 Grape sugar, C 14 H 14 O 14 OF VEGETO-ANIMAL SUBSTANCES. Under this Head are included Gluten, Vegetable Albumen, Vegetable Fibrin, and Legumen, or Vegetable Caseine. 4097. Plants contain substances which have been desig- nated as vegeto-animal, on account of their analogy with the white of egg, and the fibrin of animal matter. Nitro- gen is always an ultimate element in them, and occasion- ally sulphur and phosphorus. As they are to be found in all vegetables, to a greater or less extent, it appears pro- per to arrange them under the head of the general princi- ples of vegetables. 4098. It had long been known that wheat dough, by being enclosed and kneaded within a porous bag, while 53 412 ORGANIC CHEMISTRY. subjected to water, might be resolved into a portion which would be washed away by the water, and an adhesive por- tion left within the bag. 4099. Beccaria first drew the attention of chemists to the substance thus obtained. Subsequently, Rouelle, Jr., demonstrated the existence in the expressed juices of many plants, of a substance coagulable by heat, like animal albu- men. This coagulable matter was, by Fourcroy, deemed to be of the same nature as the albumen of eggs. Subse- quently, Einhof demonstrated the existence, in rye, barley, peas, and beans, of two vegeto-animal substances; one re- sembling white of egg, the other, which he designated as gluten, was not considered as resembling any animal sub- stance. 5000. It may be inferred, from the account of gluten given by Berzelius, that both Einhof and Taddei subjected the gluten of Beccaria to boiling alcohol, and thus resolved it into two substances; one similar to albumen in its pro- perties, the other soluble in alcohol, especially when boil- ing, and possessing, in a high degree, the adhesiveness and other properties by which gluten had been distinguished. 5001. The matter taken up by the boiling alcohol was, by Taddei, designated as gliadine, from y A<, glue, the por- tion remaining undissolved, zimome, from yfM7 , leaven. Berzelius treats the matter, soluble in alcohol, as gluten nearly pure, and the residue as vegetable albumen, and gives the following account of the sources and properties of gluten and the vegetable albumen with which it is as- sociated. Gluten. 5002. It owes its name to the adhesive property which it possesses, and which it communicates to wheat dough. It exists in the seed of the grape, and of the cerealia es- pecially; also in those of leguminous plants, such as peas and beans, in which it is found in combination with starch and vegetable albumen. Its distinguishing characteristics are as follows. When isolated, it is almost insoluble in water. It is gluey when moist, yellow and translucent when dry. Ordinarily, it has an acid reaction with litmus, in consequence of the presence of acetic and phosphoric acid. It is soluble in alcohol, especially when boiling, and likewise in diluted aqueous solutions of acids, caustic alka- OP VEGETABLE ALBUMEN. 413 line leys, &c. It is precipitated from the latter by ferro- prussiate of potash. With nut-galls it gives a precipitate, which is not redissolved even by ebullition. N Vegetable Albumen. 5003. It is found in the above mentioned seeds in com- bination with gluten ; in seeds which yield emulsions, as, for instance, in almonds; and likewise in the seeds of the ricinus, where it is found in combination with an oil. It exists in all vegetable juices which coagulate with heat. Vegetable albumen is soluble in water, until coagulated by heat, but is not soluble in alcohol; it is not adhesive, and by desiccation becomes opaque, and of either a white, gray, brown, or black colour. It dissolves readily in caustic alkaline solutions, neutralizing their caustic taste, and is precipitated by a great excess of acid. The pre- cipitate is a chemical compound of albumen with the acid, soluble in water when pure, but less so when this liquid is acidulated. 5004. The aqueous solution of vegetable albumen is precipitated by acids, by ferro-prussiate of potash, by chlo- ride of mercury, and infusion of galls; being, in these re- spects, perfectly analogous to animal albumen. 5005. Gluten and vegetable albumen spontaneously un- dergo decomposition, accompanied by an evolution of am- monia, a production of the acetate of ammonia, and like- wise the fetor which distinguishes the putrefaction of ani- mal substances. At a certain period of putrefaction, they have, whether separate or mixed, the smell of old cheese. Of the Gluten and Albumen of Wheat. 5006. If we make a thick paste of wheat with water, in a porous bag, and knead this paste within the bag, under water, until this liquid is no longer rendered milky, there remains, finally, a gray coherent elastic residue. This residue consists mainly of a mixture of gluten and vegeta- ble albumen, not quite free from other matter derived from the wheat, and more or less of starch, which it is difficult to remove completely. This residue does not contain the whole of the vegeto-animal matter of the wheat, a part being carried away by the water during the kneading of the paste. 414 ORGANIC CHEMISTRY. 5007. To separate from each other the albumen and gluten proper, contained in the gluten of Beccaria, it is ne- cessary to subject it to boiling alcohol, till this liquid, on being filtered, is not made turbid by cooling. The alcohol dissolves the gluten proper, as well as another substance imperfectly known, leaving the vegetable albumen. The gluten is obtained by mixing the alcoholic solution with the water, and removing the alcohol by distillation. A liquid remains, in which the gluten floats in coherent volu- minous flocks. A very small portion of gluten remains in solution, combined with gum. 5008. The gluten being separated from the liquid, is of a pale yellow, and readily becomes agglutinated into a mass, which sticks to the fingers, is elastic, insipid, and endowed with a peculiar odour. In dry air it becomes spontaneously polished on the outside, and of a deeper yellow, drying, by little and little, into a translucent mass of a very deep yellow, resembling dried animal matter. Alcohol dissolves the gluten, and the solution, which is of a pale yellow, being evaporated, the gluten remains in the form of a yellow transparent varnish. If the gluten be macerated in cold alcohol, it is whitened, and forms a milky solution, from which an insoluble matter is depo- sited. This is not gluten, though of a kindred nature, being soluble by the aid of ebullition; the resulting solu- tion, when concentrated, acquires a mucilaginous consist- ence on cooling. Gluten dissolves in boiling officinal alco- hol, and precipitates by refrigeration, without having lost its gluey quality. It is insoluble in ether, or in fixed oils or volatile oils. If we subject it to acetic acid, it becomes, in consistency, mucilaginous, semi-liquid, losing its yellow colour. Mixed in this state with water, it gives a muci- laginous flocky residuum and a milky solution. 5009. From the investigations of Einhof, as stated by Berzelius, it appears that a matter, analogous to that above described as true gluten, may be obtained from rye, barley, oats, or even from maize, which, from the absence of any cohesiveness in its moistened meal, would not be supposed to contain any matter deserving to be distin- guished as gluten. 5010. It will be perceived, from the preceding history of the opinions and observations of chemists, respecting the vegeto-animal matter obtained from wheat and the seeds OF THE GLUTEN AND ALBUMEN OF WHEAT. 415 of other vegetables, that the idea lately put forth by Lie- big, respecting the identity of their composition with ani- mal albumen, has long been entertained, though never be- fore presented so forcibly to popular attention. 5011. Respecting the matter treated as gluten by Ber- zelius, Liebig advances views which are in some respects new, and somewhat discordant. I will here quote the lan- guage of the author last mentioned: " These nitrogenized forms of nutriment in the vegetable kingdom may be re- duced to three substances, which are easily distinguished by their external charac- ters. Two of them are soluble in water, the third is insoluble. " When the newly-expressed juices of vegetables are allowed to stand, a separa- tion takes place in a few minutes. A gelatinous precipitate, commonly of a green tinge, is deposited, and this, when acted on by liquids which remove the colouring matter, leaves a grayish white substance, well known to druggists as the deposite from vegetable juices. This is one of the nitrogenized compounds which serves for the nutrition of animals, and has been named vegetable fibrin. The juice of grapes is especially rich in this constituent, but it is most abundant in the seeds of wheat, and of the cerealia generally. It may be obtained from wheat flour by a mechanical operation, and in a state of tolerable purity; it is then called gluten, but the glu- tinous property belongs, not to vegetable fibrin, but to a foreign substance present in small quantity, which is not found in the other cerealia. 11 The method by which it is obtained, sufficiently proves that it is insoluble in water; although we cannot doubt that it was originally dissolved in the vegetable juice, from which it afterwards separated, exactly as fibrin does from blood. "The second nitrogenized compound remains dissolved in the juice after the sepa- ration of the fibrin. It does riot separate from the juice at the ordinary temperature, but is instantly coagulated, when the liquid containing it is heated to the boiling point. " When the clarified juice of nutritious vegetables, such as cauliflower, asparagus, mangel wurtzel, or turnips, is made to boil, a coagulum is formed, which it is abso- lutely impossible to distinguish from the substance which separates as coaarulum, when the serum of blood or the white of an egg, diluted with water, are heated to the boiling point. This is vegetable albumen. It is found in the greatest abundance in certain seeds, in nuts, almonds, and others, in which the starch of the gramineae is replaced by oil. " The third nitroorenized constituent of the vegetable food of animals is vegetable caseine. It is chiefly found in the seeds of peas, beans, lentils, and similar legu- minous seeds. Like vegetable albumen, it is soluble in water, but differs from it in this, that its solution is not coagulated by heat. When the solution is heated or evaporated, a skin forms on its surface, and the addition of an acid causes a coagu- lum, just as in animal milk. "These three nitrogenized compounds, vegetable fibrin, albumen, and caseine, are the true nitrogenized constituents of the food of graminivorous animals; all other ni- trogenized compounds, occurring in plants, are either rejected by animals, as in the case of the characteristic principles of poisonous arid medicinal plants, or else they occur in the food in such very small proportion, that they cannot possibly contribute to the increase of mass in the animal body. " The chemical analysis of these three substances has led to the very interesting result that they contain the same organic elements, united in the same proportion by weight; and, what is still more remarkable, that they are identical in composi- tion with the chief constituents of blood, animal fibrin, and albumen. They all three dissolve in concentrated muriatic acid with the same deep purple colour; and even in their physical characters, animal fibrin and albumen are in no respect different from vegetable fibrin and albumen. It is especially to be noticed, that by the phrase, identity of composition, we do not here imply mere similarity, but that even in re- gard to the presence and relative amount of sulphur, phosphorus, and phosphate of lime, no difference can be observed." 5012. In addition to the information conveyed in the preceding quotation, we are informed in a note (8) that 416 ORGANIC CHEMISTRY. the portion of wheat flour, above alluded to, under the name of fibrin, is that which is not taken up by boiling al-- cohol from the glutinous mass mechanically obtained by washing wheat dough in a bag. 5013. The vegetable fibrin of Liebig is, therefore, the vegetable albumen of Einhof and Berzelius, or the zimome of Taddei. 5014. The statement in the note, that "pure gluten is the portion of raw wheat flour which is soluble in hot alcohol" is not consistent with the allegation, that the glutinous quality is due to a foreign substance present in small quantity, and which is not found in other cerealia. This allegation is, moreover, inconsistent with the observations of Einhof, as stated by Berzelius, that gluten is found in rye, barley, and in small proportion in maize. Besides, it is difficult to be- lieve that the adhesiveness of wheat dough, to which it owes its power of confining the carbonic acid generated during panification, can be the effect of a small quantity of/ foreign matter. It would seem to require a quantity of matter intimately associated with the farina, and pervading the whole of the dough, into which it is converted in the bread making process. 5015. There seems, however, to be good grounds to suppose the existence of an error in estimating the nourish- ing power of different kinds of grain, to be in proportion to the quantity of glutinous matter obtained from them by washing, since the farina of maize, which for equal weight is in this country considered at least as nutritive as wheat, seems to have not perceptible adhesiveness. Hence, the statement of Liebig, however inconsistent with precon- ceived opinions, may point towards an important truth, that there is a vegetable fibrin meriting the highest rank as animal food, which differs from pure gluten in not being soluble in alcohol nor glutinous; and from vegetable albu- men, in not being soluble in water, nor coagulable by heat. 5016. The idea, above quoted from Berzelius, respect- ing the superiority of wheat as a nutriment, being due to its holding a peculiarly large* proportion of gluten, has ge- nerally prevailed ; and by Sir H. Davy the opinion was entertained, that the wheat of more southern climates was, on account of a greater abundance of gluten, more nutri- tious than grain of the same kind, raised in colder lati- tudes. To a greater abundance of the same matter, has OF THE GLUTEN AND ALBUMEN OF WHEAT. 417 been ascribed the superior capability in wheat dough of what is called rising; as the gluten, by preventing the escape of carbonic acid, causes the inflation of innumera- ble little cavities producing the cellular structure which distinguishes leavened bread. 5017. It appears, that during panification there is ac- tually a generation of alcohol, as well as carbonic acid, so that in the usual process there is an incipient fermenta- tion. 5018. Gingerbread, however, owes its lightness to a dif- ferent process. Being made of flour and molasses, with a suitable addition of an alkaline carbonate, an acid is gra- dually generated by the absorption of atmospheric oxygen, which displaces the carbonic acid from the carbonate, (1198.) The gas, thus liberated from the alkali, being confined by the gluten, when the bread is placed in an oven, an inflation of every part arises from the expansion of the gaseous matter. 5019. A bicarbonate is more efficacious than pearlash in causing gingerbread to rise, as in proportion to the al- kali it yields double the quantity of gas. A bicarbonated alkali is found to act as a leaven for cakes, when old cider is mingled with the dough. Tartaric acid has been used for this purpose, and lime juice might be employed, or any well flavoured vegetable acid. An equivalent portion of chlorohydric acid might be resorted to. 5020. It is supposed that bakers generally use a sufficiency of pearlash to neutralize the acidity which is liable to supervene in their yeast or lea- ven; and that latterly, carbonate of soda having become cheaper, has been preferred. An erroneous prejudice has existed as respects this practice, whereas evidently sourness in bread must be more injurious to health than an alkaline acetate. 5021. Carbonate of ammonia has been used, and is alleged, by being vapourized during the baking process, to contribute to the inflation and con- sequent sponginess of the bread in which it is used. 5022. More than forty years since, a candidate for graduation in our university, Dr. Pennington, published a thesis, in which bread was described as being simultaneously salted and raised, by the addition to the dough of chlorohydric acid and carbonate of soda, in due proportion. Rolls are al- leged to be rendered lighter, when made with carbonated water, of the Con- gress spring at Saratoga. The knowledge which we now have of the equi- valent proportions in which to use bases and acids, renders experiments of this kind much more easy than they were at the period when Dr. Pen- nington graduated. Of course a bicarbonated alkali should in all cases be preferred, for the reason above given. 418 ORGANIC CHEMISTRY. Legumen, or Vegetable Caseine. 5023. The substance bearing these names, appears to be intermediate between gluten and vegetable albumen, not being coagulable by heat like the one, nor like the other soluble in alcohol while insoluble in water. It is, however, alleged by Liebig, that agreeably to recent ana- lyses made in his laboratory, there is no difference as re- spects composition, between gluten, vegetable albumen, vegetable fibrin, and vegetable caseine, nor between these substances and those of the same names derived from ani- mals. Composition of Vegetable Fibrin, Vegetable Albumen, Vegetable Caseine, and Vegetable Gluten. VEGETABLE FIBRIN. Sherer.* a Carbon Hydrogen Nitrogen Oxygen Sulphur Phosphorus I. ii. in. 53.064 54.603 54.617 7.132 7.302 7.491 15.359 15.809 15.809 Jones.* 6 IV. 53.83 7.02 15.58 Gluten, as obtained from wheat flour. Marcet. c Boussingault. 55.7 14.5 7.8 ii. 53.5 15.0 7.0 24.445 22.285 22.083 a Ann. der Chem. und Pharm. XL. 7. c L. Gmelin's Theor. Chemie, II. 1092. 23.56 22.0 24.5 b Ibid. XL. 65. VEGETABLE ALBUMEN, a Carbon Hydrogen Nitrogen Oxygen Sulphur Phosphorus From Rye. Jones.* 54.74 7.77 15.85 > 21.64 Carbon - Hydrogen Nitrogen Oxygen, &c. Wheat. Jones.* 55.01 7.23 15.92 21.84 Gluten. Varrentrapp & Will.* 54.85 6.98 15.88 22.39 ingault. i27 52 6.9 18.4 22.0 Almonds. Jones.* 57.03 7.53 13.48 21.96 Varrentrapp and Will.* 15.70 a Ann. der Chem. und Pharm. XL. 66, and XXXIX. 291. VEGETABLE CASEINE. a Scherer.* 54-138 7.156 15.672 23.034 Jones.* 55.05 7.59 15.89 21.47 Sulphate of Caseine and Potash. Varrentrapp and Will. Carbon Hydrogen Nitrogen Oxygen, &c. a Ann. der Chem. und Pharm. XXXIX. 291, and XL. 8 and 67. 5141 7.83 14.48 51.24 6.77 13.23 OF VEGETABLE COLOURING MATTER. 419 VEGETABLE GLUTEN. Jones.* a Boassingault. Carbon - - 55.22 54.2 52.3 Hydrogen - - 7.42 7.5 6.5 Nitrogen - - 15.98 13.9 18.9 Oxygen, &c. - 21.38 24.4 22.3 a Ann. der Chem. und Pharm. XL. 66. The pure gluten, analyzed by Jones, was that portion of the raw gluten from wheat flour which is soluble in hot alcohol. The insoluble portion is vegetable fibrin, the analysis of which has been already given. Composition of Animal Caseine. a Scherer. From fresh milk. From sour milk. . A From milk by acetic acid. Albuminous sub- stance in milk, b I. 54.825 7.153 15.628 ^^ II. 54.721 7.239 15.724 ^l in. 54.665 7.465 15.724 IV. 54.580 7.352 15.696 54.507 6.913 15.670 22.394 22.316 22.146 22.372 22.910 Carbon Hydrogen Nitrogen Oxygen > Sulpnur a Ann. der Chem. und Pharm. XL. 40 et seq. b This substance, called, in German, zieger, is contained in the whey of milk after coagulation by an acid. It is coagulated by heat, and very much resembles albumen. Mulder, a Carbon 54.96 Hydrogen 7.15 Nitrogen 15.89 Oxygen ..... 21.73 Sulphur 0.36 a For the analysis of vegetable caseine, see the preceding page. Of Vegetable Colouring Matter, or Dyes, and of Dyeing. 5024. None of the operations of nature are more inscrutable, than those by which organic substances are endowed with the immense variety of colours with which vegetables and animals are adorned. The chemist may know how to elaborate dyes, to fix them, and in fixing them, by the interposition of mordants, to vary their hues; but excepting the influence of transparent media, or of crystalline structure, in dispersing refracted or po- larized rays, he is still quite ignorant of the differences in the arrangement of particles which 'give rise to diversity of colour; or of the mode in which chemical combination causes the various colours of precipitates. 5025. Colouring substances or dyes are divided into substantive and ad- jective dyes. The former, with little disposition to dissolve in water, have a strong affinity for the fibre to be dyed, and enter directly into union there- with. The adjective colours, having little or no affinity for the fibre to which they are to be attached, an union is produced by an intermediate sub- stance having an affinity for both, and which is consequently called a mor- dant, from mordant, biting, in French. In some cases the colour is changed by the mordant, in others improved and heightened. 5026. Lakes are precipitates of colouring matters, made by the sub- stances used as mordants. By presenting them, in a proper state of com- bination, to colouring matter, both alumina and oxidized iron are used ex- 54 420 ORGANIC CHEMISTRY. tensively as mordants, and for the formation of lakes. By means of cochi- neal dye and protoxide of tin, the well known scarlet of the military uni- form of Great Britain is produced. The ordinary carmine of commerce, is a lake produced from that dye by alumina. Chinese carmine is pro- duced by the same dye with protoxide of tin. 5027. Indigo is a substantive dye which is made to attach itself to woollen cloth, without the aid of a mordant. By digestion with lime and green sul- phate of iron, it is rendered white. When in this state it unites with the woollen fibre, and by subsquent exposure to air, regains its blue colour. The rationale of this process, suggested by Liebig, is as follows : 5028. A soluble colourless substance, which may be called indigogene being generated in the indigo plant, is by oxidizement converted into the insoluble blue indigo of commerce. In the process of dyeing, the oxide of indigogene or blue indigo is deoxidized by protoxide of iron, liberated by the lime from the sulphate, and is thus restored to its whiteness and so- lubility. In this state, combining with the organic fibre, it is subsequently reconverted into insoluble blue indigo by union with atmospheric oxygen. 5029. But Kane conceives, that Dumas has proved by analysis, that so- luble white indigo is a hydruret of insoluble blue indigo. Each atom of the hydruret being deprived of an atom of hydrogen, during the macerating process of the manufacturer, the indigo loses its solubility and assumes its appropriate blue colour. In this state it is found in commerce, and when subjected to the process of the dyer, above alluded to, is made to receive an atom of hydrogen liberated by an atom of water, of which the oxygen is simultaneously seized by the protoxide of iron. The hydruret thus formed combining with the organic fibre, while colourless and soluble, by subse- quent exposure to air is dehydrogenated, and thus again converted into an insoluble blue dye. 5030. Indigo is soluble in concentrated sulphuric acid, especially the fuming acid of Nordausen. The solution thus made, yields what is called the Saxon blue. Previously to the immersion of the cloth, the solution is neutralized by carbonate of soda, which uniting with the acid, the dye at- taches itself to the organic fibre, whether it be wool, silk, or cotton. 5031. Indigo forms various peculiar combinations, to which it would be inexpedient to direct the attention of those who study chemistry only as auxiliary to medicine. , Of the Colouring Matter of Leaves and Floivers. 5032. The green colour of plants is said to be due to the pressure of a substance called chlorophyll. This has not been obtained sufficiently pure to have any formula assigned to it. It does not contain nitrogen, is inso- luble in water, but soluble both in ether and alcohol, and in strong acids. From these, however, it precipitates on dilution. It combines with bases. 5033. Berzelius conceives three kinds of chlorophyll to exist. The first, existing in fresh leaves, dissolves in acetic acid with a rich grass-green co- lour; the second, formed from the first by drying, gives with the same acid an indigo blue solution; the third, which exists principally in the dark leaved plants, is brownish green. 5034. So potent is the colouring power of chlorophyll, that Berzelius has calculated that all the foliage of a large tree seldom contains ten grains of it. When trees change colour in the fall, chlorophyll is, according to. the same chemist, replaced by other colouring matter. OP OILS. 421 5035. Chlorophyll floats in the cells, existing in the green leaves of plants in general, in the form of green globules, from which it may be ex- tracted by ether. The etherial solution thus obtained, being subjected to the distillatory process to remove the solvent, the residue is digested in al- cohol, which takes up impure chlorophyll. The alcohol, being entirely re- moved, the residual matter is subjected to concentrated chlorohydric acid, by which a fine emerald green colouring matter is dissolved. This precipi- tating on dilution, is digested in a strong lixivium of potash. The resulting compound being dissolved by water, the solution, after being filtered, is satu- rated with acetic acid, when beautiful green flocks precipitate of pure chlo- rophyll, which in drying become bluish green. Graham, 907. Of Oils. 5036. When not figuratively used to describe substances having only an oleaginous consistency, like oil of vitriol, the word oil has been applied to two classes of substances, differing in most respects in their properties and chemical constitution. One of these classes has been called fixed, from their insusceptibility of being distilled without decom- position. But as margaric acid, a principal constituent in a majority of fixed oils, and spermaceti, a concrete animal oil, may be distilled without change, this definition is not universally consistent. It would, therefore, be preferable to designate as fixed oils those which do not spontaneous- ly evaporate when exposed to the air, or which are not vaporized at the boiling point of water, when subjected to the distillatory process with that liquid.* Of Fixed Oils. 5037. I propose rather to treat briefly of the general properties of fixed oils, of their composition, and of the theory of their conversion into soap, than to give an ac- count of each of them particularly. 5038. There is no essential difference between fat, and oil. The one differs from the other, merely, in a greater * By distinguished writers, such oils have been designated as fat or unctuous oils. But as unctuous and oily are synonymous words, and as fats are concrete oils, the use of the words in question, in the way alluded to, were equivalent to saying oily oils, or fat fats. The word greasy though inelegant, would be more appropriate, simi- larly applied, than unctuous, as one of the most characteristic differences between volatile and fixed oils is the presence of this property in the one, and its absence from the other. Kane distinguishes fixed oils as saponifiable. But as chemists consider compounds of certain oily acids with bases as soaps, evidently (4032) fixed oils are native compounds meriting this appellation; as will shortly be made more evident. It is the oily acid ingredient, not the compound formed with it, which can be saponified. I should conceive it, therefore, more proper to designate the oils in question, as soap oils, or unctuous soaps. 422 ORGANIC CHEMISTRY. propensity to the fluid state. That which may pass for fat in winter, may become oil in summer. The oils of an- imals are generally in the solid state of fat; those of ve- getables are generally liquid. 5039. Although fats and oils, as they exist in nature, appear to be homogeneous, they all consist of two or more oleaginous substances, of which one is more fluid than the rest. The more fluid ingredient, named olein, is found in its chemical habitudes and composition to be the same in a great majority of instances, but the less fluid portion con- sists very extensively of a matter called stearine, more or less associated with another, rather more fusible and much more soluble in alcohol and ether, called margarine. In- deed, this last mentioned substance abounds in human fat, and in that of some other animals, and in vegetable oils predominates. Besides margarine and stearine, the fol- lowing analogous substances have been noticed in various kinds of fat, or oily matter; as for instance, spermaceti in the cachalot whales; delphinine in the oil of the dolphin and common whale; butyrin, caproin and caprin in butter; myristicine in butter of nutmegs; ricino stearine, ricino olein, and ricin, in ricinus communis; crotonine in the oil of crotontiglium; cocostearine in cocoa nut oil ; palmatine in palm oil.* 5040. Spermaceti is obtained, as is well known, from the crania of cachalot whales, whence its inappropriate name, from sperma, seed, and cetus, a whale. The part allotted to it, is analogous to that which stearine performs in tallow or suet ; but that it differs in composition has been already mentioned, and to keep it in fusion requires a temperature peculiarly high. Hence it crystallizes from its solvent olein, at the ordinary temperature of the air. 5041. The summer strained and winter strained oils of commerce, severally consist, the one of a large portion of olein, with a small proportion of stearine, the other of the same materials, but with a greater proportion of the more solid constituent. The appellation given to these oils, conveys the idea of the fact, that the one is obtained by * Mr. Stenhouse having isolated the stearine of palm oil, alleges its formula to be as follows, C 33 H 66 O 4 ; and that it consists of one atom of a peculiar fat acid, which he calls the palmatic, C 32 H 62 -j- O 3 , and one atom of oxide of glyceryl. He assigns, however, a new formula for the latter, C 3 H* Qi, which Berzelius does not consider as admissible upon the evidence of this author alone, while inconsistent with the previous analysis made by Liebig and Pelouze. OF OILS. 423 straining at a lower temperature than the other. In like manner, a liquid may be obtained from crude olive oil when thickened by cold, which, when employed to lubri- cate delicate machinery, like that of watches, does not, by congealing, impede the movements in frosty weather. 5042. Subsequently, the following more effectual process was discovered by Chevreul, of isolating the constituents of oil, whether liquid or in the concrete state of fat. 5043. The whole being dissolved in boiling alcohol, the margarine and stearine separate by congelation on cool- ing. The mass thus separated is subjected to ether, with as much heat as the low boiling point of this solvent will permit. The margarine is taken up by the ether, in which it is soluble, leaving the stearine undissolved. Of course, by distillation, the alcohol may be removed from the olein, the ether from the margarine. 5044. Stearine is white, crystallizable, soluble in alcohol when boiling, but insoluble in cold alcohol, water, or ether. 5045. It is best obtained from mutton suet, by washing with ether as long as any thing is taken up, or by agitating melted suet with six times its volume of ether, and subject- ing the mass, when cold, to intense pressure. In either case the ether removes the olein and margarine, leaving the stearine pure. Thus obtained, it is usually crystalline. Like spermaceti it is not in the least greasy to the touch, and is easily pulverized. It is insoluble in ether or alco- hol, when cold, but is soluble in those liquids when boiling, and by refrigeration crystallizes from the solution. 5046. Stearine consists of an atom of glycerine or oxide ofglyceryl, C 6 H 7 O 5 Two atoms stearic acid, C 136 H 132 O 10 Two atoms of water, - - - H 2 O 2 Hence the formula of stearine is - C 142 H 141 O 17 5047. Margarine is obtained from the ether employed as above mentioned to depurate stearine, by vaporizing the ether, and redissolving the mass in boiling alcohol. From this alcoholic solution the margarine crystallizes, on cooling, any olein which may be present remaining dis- solved. Excepting its greater fusibility, melting at 118, and its solubility in alcohol and ether, already mentioned, it much resembles stearine. 424 ORGANIC CHEMISTRY. 5048. Its composition will appear from the following formula of its ingredients : One atom oxide of glyceryl, - C 6 H 7 O 5 Two margaric acid, C 68 H 66 O 6 One water, - - HO Formula of margarine, - C 74 H 74 O 12 5049. Olein. In concrete oils, usually called fats, olein exists in but a small proportion, but constitutes a large portion of all the fixed oils which are not drying, or, in other words, capable of hardening by exposure to the air. As found in nature, it always holds more or less stearine and margarine. Margarine abounds in olive oil. In the oil obtained from sweet almonds by expression, there is less margarine in proportion to the olein than in any other. In this respect rape seed oil approximates most nearly to the oil of sweet almonds. 5050. Olein is best obtained by dissolving almond oil in ether heated nearly to its boiling point, and afterwards cooled till the margarine congeals, so as to be separated by straining. Olein, thus obtained, remains liquid at zero, F. 5051. The composition of olein is inferred to be as fol- lows : One atom of glyceryl, - - C 6 H 7 O 5 Two oleic acid, C 88 H 78 O 8 Two water, - - - H 2 O 2 Hence the formula of olein is - - C 94 H 87 O 15 Of Saponification. 5052. In treating of glyceryl and cetyl (4029, 4036), it has been explained, that all fixed oils, whether concrete or liquid, are supposed to be compounded of two ingredients, one acting as a base, the other as an acid, and that in a great majority of cases an oxide of glyceryl is inferred to be the base. Hence, when substances in which it exists in this capacity are boiled with an alkaline oxide, the oxide of glyceryl is dispossessed of its acid. The acids thus trans- OF SAPONIFICATION. 425 ferred to the alkaline oxide have been named from the substances by which they are respectively yielded. Thus Stearine gives Stearic acid. Margarine Margaric acid. Olein Oleic acid. Butyrin ) Butyric acid. Caproin Caproic acid. Caprin } Capric acid. Delphinine Delphinic acid. Myristicine of Nutmeg Butter Myristicic acid. Ricino Stearine } Ricino Stearic acid. Ricino Olein > Castor Oil Ricino Oleic acid. Ricin ) Ricinic acid. Crotonine, Oil of Croton Tiglium Crotonic acid. Cocoa Stearine Cocoa Stearic acid. 5053. It remains doubtful whether the acids thus elabo- rated exist ready formed, in union with the oxide of glyce- ryl, or whether both base and acid are generated during the process of saponification. The former opinion, how- ever, is supported by the fact, that, by the direct union of stearic acid with the oxide of ethyl, an oil is formed, which, on being cooled below 90, solidifies with all the a~ppearance of a fat. If the artificial fat, consisting thus of ethyl, be boiled with caustic potash, the results of the reac- tion of that alkali with stearine, under similar circum- stances, are exactly reproduced ; except that while stea- rate of potash is formed in both cases, an oxide of ethyl is liberated in the latter instead of the oxide of glyceryl. It may, therefore, be presumed, that stearine, olein, &c., may be regarded as definite salts formed by the union of the fat acids, which are respectively produced from them with the oxide of glyceryl. 5054. The oxide of glyceryl is the base of a majority of oleaginous bodies, the difference between them being pro- duced by the diversity of the acids which enter into their composition. In the single case of spermaceti this general rule is reversed, the acids being the same as those which are present in large quantities in the fat of men or of sheep, while the base is the oxide of another radical, cetyl, capa- ble, as already mentioned, of combining with sulphuric acid to form a compound corresponding to sulphovinic acid, and likewise of existing as a hydrate, or in a state analogous to 426 ORGANIC CHEMISTRY. that of ethyl in alcohol. It would appear, therefore, that while we must regard common tallow, or suet, as a stea- rate, margarate, and oleate of oxide of glyceryl, sperma- ceti must be looked upon as a margarate and oleate of oxide of cetyl. It may be observed, that the view of the composition of the different fats here given, and founded on the fact of their decomposition by alkalies into an acid and a base, is confirmed by the result of direct analysis, which, when disposed in a rational formula, in all cases gives the number of atoms necessary to represent the or- ganic acid and base which they are supposed to contain. 5055. In a paper published in the last number of the American Journal of Science, Dr. Smith, as the result of a careful analytical investigation, alleges that ethalic acid is the sole electro-negative product of reaction of spermaceti with alkalies, in the process of saponification ; and that the margaric and oleic acids, are not evolved by that pro- cess. He supposes that an atom of spermaceti, C 64 H 64 O 4 , is separated by the action of potash into an atom of ethalic acid, C 32 H 31 O 3 , and one atom of ethal, C 32 H 33 O. From the fact that the ethal, thus separated, by a farther treat- ment with potash at a high temperature and with access of air, may be completely converted into ethalic acid, Smith infers that the saponification of spermaceti differs from that of ordinary fats, since the glycerine, which they yield, is insusceptible of further acidification: also that sperma- ceti must be regarded as a homogeneous fatty body, not containing, ready formed, either the acid or base which it affords when treated with alkalies. Properties of the Fixed Oils. 5056. I infer that fixed oils, when not accompanied by any other matter, are nearly colourless, insipid, and in- odorous. The smell and taste produced by them, in the state in which they come under our observation, is ob- viously due to some volatile oil or acid with which they are associated. Their colour is evidently caused by foreign matter, as they may be decolorized by charcoal. In some instances impurities exist in them naturally, in others are produced during their elaboration or subsequent expo- sure to atmospheric oxygen, by which they are more or less oxidized, and brought into the state called rancidity. The fine flavour of fresh grass butter, and the nauseous PROPERTIES OF THE FIXED OILS. 427 savour of that which is rancid, are neither of them to be ascribed to the pure oil of butter, which, when fresh made from cream obtained from cows fed on hay, although sweet, is not highly flavoured. 5057. The difference between cold pressed olive, or cas- tor oil, and that obtained with the aid of heat, shows, that in proportion as substances of this kind are more near to the natural state, the less they are endowed with colour, or any activity as respects taste or smell. 5058. Boiling with magnesia, diminishes the unpleasant smell and taste of rancid oils, by removing the acid which causes those defects. 5059. As in every animal, and in a great number of ve- getables, fixed oils are more or less to be found, of which each affects the sight, the smell, and taste, in a different way, it might be imagined that there was much difference in the proportions of the ultimate elements of which they are formed.* 5060. But it has already been made evident, that, in or- ganic products especially, diversity of properties, is not at- tended by corresponding diversities in the proportions of ultimate elements. However, in the case of the substances under consideration, it is probable that there would be very little difference in properties to be accounted for, could those substances be obtained free from certain volatile oils and acids by which they are accompanied. It is not, therefore, surprising, that the results of ultimate analysis do not display any material difference as to the ratio in which carbon, hydrogen, and oxygen, enter into their com- position. 5061. Agreeably to quotations made by Raspail, of the ultimate analysis, by various distinguished chemists, of twelve species of oils, including white wax, it appears that the differences resulting from the diversity in composition, * Mr. M. S. Wright has, by means of ether, extracted from spurred rye or ergot (secule coruntum) a fat and saponifiable oil, which has the odour of the ergot, and which he alleges to have a like efficacy. This oil is changed by exposure to air, es- pecially if simultaneously heated, becoming, in consequence, brown. Nevertheless it may be kept unchanged, in well closed vessels. It is soluble in alcohol, ether, sulpho-carbonic acid, and fixed and volatile oils. Berzelius deems it worthy of a more thorough examination. Report for 1841, page 150. It may be inferred, so far as reliance is to be placed on the statement of Mr. Wright, that the active principle of ergot is associated with the oil abovementioned. No reference is made to the ergotin of Wiggers, supposed by him to be the active principle of ergot. U. S. Dispensatory, 585. 55 428 ORGANIC CHEMISTRY. are less than those arising from variation in the manipula- tions of the different analysts. 5062. There seems, however, to be some justification for the idea, that in concrete oils there is more carbon; and that solubility in alcohol increases with the proportion of oxygen. 5063. The carbon in the less fluid portion of olive oil is to that in the more fluid portion, as 82-? -f- 2HO, being a bibasic acid. The orange-coloured oil, formed simul- taneously with elaidic acid, has not been well examined. Pure elaidic acid fuses at 113, and is soluble both in alcohol and ether. In the reaction of olive oil with nitrate of mercury, by which citrine ointment is made, both elaidic acid and the orange-red oil are produced. To the latter the cha racteristic smell and hue of the ointment is attributed. 430 ORGANIC CHEMISTRY. 5071. Agreeably to the same rationale, inverting a lighted candle causes an extinction of the flame. On the other hand, any volatile oil in the vicinity of an ignited body forms, on contact with the air, a superstratum of va- pour intermingled with atmospheric oxygen, so as to con- stitute an inflammable mixture. Hence the approach of any thing ignited or inflamed, causes a conflagration of the whole surface. This makes it evident wherefore, in the combustion of fixed oils, as in lamps and candles, a wick is requisite, which being brought into a state of combustion at the upper extremity, and drawing up the oleaginous matter by capillary attraction, causes minute portions to be successively subjected to the heat requisite to a decom- position into the combustible gas and vapour, by which flame is, in such cases, supported. 5072. Although volatile oils may be described as im- miscible with water, they are not like those of the other class perfectly insoluble in that liquid. Hence rose water, cinnamon water, peppermint water, as well as many ana- logous preparations, are formed by the union of a minute portion of an essential' oil with water, during its distillation from the native product containing the oil, or from a por- tion of it previously procured. 5073. Water by agitation with a fixed oil, may acquire a savour resembling that associated with the oil, but this is owing to a solution of the foreign matter to which that savour is due, rather than the presence of the oil itself. Yet the repulsion which exists between the oily, and aqueous particles, causes a surprisingly rapid distribution of oleaginous liquids over the surface of the water, so that it is difficult to remove every trace of greasiness after it has been imparted. It is in consequence of this proper- ty that oil has been found to abate the size and duration of waves by lessening that hold of them, taken by the wind ; to which they owe their existence. 5074. The great affinity existing between fixed and vo- latile oils, renders it possible to combine them in any pro- portion. The volatile oil, being usually the most liquid, is considered as the solvent, and this appears especially pro- per, when oil, in the solid form of fat, is taken up by them. Hence the efficacy of oil of turpentine in removing paint, which consists of a drying oil and the metallic compound, forming the pigment. Hence, also, the oil of turpentine OF VOLATILE OILS. 431 is used to attenuate paints and varnishes, made with sic- cative oils. 5075. The readiness with which fixed oils imbibe those of the volatile kind, has led to their employment in se- curing the delicate essences of certain flowers. The odo- riferous petals being stratified between alternate layers of carded cotton, imbued with an inodorous fixed oil, their essence is taken up by the latter, and is subsequently se- parated by distillation with water.* Of Volatile Oils in particular. 5076. After the efforts made in the preceding pages, to discriminate fixed from volatile oils, it must be evident, that the latter are distinguished from the former, by sus- ceptibility of spontaneous evaporation, and of being dis- tilled with the steam of boiling water, by greater inflamma- bility, the absence of greasiness, superior solubility in water or alcohol, and lastly, an insusceptibility of being decomposed by alkaline and other bases, so as to yield to the latter saponifiable, oily acids. Like fixed oils, many volatile oils consist of a more fluid, and a less fluid oil, of which the former is, of course, more readily congealed by cold. They are also prone, like fixed oils, to absorb oxy- gen, and to have a portion of their hydrogen removed by uniting therewith; being thus partially converted into a resinous mass, which remains in solution in the rest of the oil. 5077. By some chemists, the less fusible or liquid por- tion is called stearopten, the more liquid part, elaopten. By others, the words stearessence and oleessence are sub- stituted, respectively, for the names above mentioned. 5078. In some respects there is a great analogy in the properties of volatile oils and ethers. The latter as respects volatility, incapacity to mix with water, solubility in alco- * For removing oils from clothes, oil of turpentine or any other volatile oil may be used, burfollowed by some inconvenience from the smell of the oil enduring for some time afterwards. By enclosing the greasy spot between folds of blotting pa- per, and applying a hot smoothing iron to the paper, the oil is drawn up hy capillary attraction; and the more readily if its bulk and fusibility be previously increased by the addition of an essential oil. It is by capillary attraction that moistened clay, in drying, draws grease out of a floor; and in like manner leather is, by previous moistening, made to take up oil, applied to it superficially, as the moisture is vaporized. Strong alcohol, especially when hot, may be used to extract grease; also aqua ammonia, or the alcohol and ammonia, without being heated, may^be united for this purpose, with still greater effect. 432 ORGANIC CHEMISTRY. hol, and ability to unite in all proportions with volatile oils, cannot be distinguished from them. But as to com- position there is no analogy; while between fixed oils and certain ethers, both consisting of acids in union with an oxidized compound radical, the analogy in composition is perfect. 5079. Volatile oils may be arranged into several sets, or classes, according to their origin. ,5080. 1st. Oils directly produced by vegetables and ex- tricated by pressure, heat, or solvents, so as to be obtained in their native state. 5081. 2d. Oils which result from the reaction of the proximate elements of vegetation, as the oil of bitter al- monds, of spirea, and black mustard seed. 5082. 3d. Oils which have been produced by the reac- tion of their ultimate elements during destructive distilla- tion, or by the reaction of organic substances with chemical agents. Among these we may place mineral naphtha, coal naphtha, kreosote, camphogen, caoutchouchine, and a great variety of liquids resulting from the exposure of bituminous or resinous substances to heat. 5083. It must be evident that for almost every flower and fruit, as well as many leaves and roots, there is an appropriate odour; and moreover, that in some instances, as in that of the orange, different parts of the same plant will be productive of different odours. In all cases where such odours are observed, we have good reason to infer the existence of a peculiar volatile oil. It is plainly among the wonders of the creation, that such diversity of proper- ties should be found in substances of which a great number consist, as far as chemical skill can determine the question, of only two ultimate elements, carbon and hydrogen, which are severally, when isolated and pure, inodorous. Many different kinds of non-oxygenated volatile oils are com- posed of these elements in the same proportion. 5084. The volatile oils generated by vegetation, are gene- rally extricated by subjecting the substance containing them to distillation with water, when, agreeably to the Daltonian law (229) that one vapour acts as a vacuum to another, a portion of the oil comes over, bearing the same ratio to the aqueous steam, that the tension of the one vapour in vacuo would have to that of the other. Thus, supposing that at 212 the oil would boil, when within the containing OF VOLATILE OILS. 433 vessel the pressure should be equal only to five inches of mercury, while the aqueous steam may be formed under a pressure of 30 inches, then the vapour which would come over when they are both subjected to distillation at 212, would be a mixture of five volumes of steam for one of vaporized oil. 5085. Some oils are obtained by expression, those of the skins of oranges and lemons for instance, while others are procured by maceration in fixed oils (5075), which, when inodorous, may be used as a vehicle for their subsequent application, or may be made to give them up by distillation with water, as already mentioned. 5086. Ether may be advantageously employed to isolate volatile oils. It is an excellent solvent of them, and when quite pure evaporates, leaving them unchanged. 5087. When distilled or evaporated without protection, there is a reaction between them and atmospheric oxygen, or other impurities, by which more or less resin is gene- rated. Hence, when used as solvents for resins, they do not dry off as well as alcohol or ether. The affinity which oil of turpentine has for some resins, common resin among others, is so great that mere evaporation in the air never causes its entire removal from them. 5088. By agitation with diluted sulphuric acid with al- cohol, or preferably with a solution of chloride of calcium in alcohol, the resin may be removed from an essential oil, as is shown by the colour imparted to the detergent liquid, and the diminution of that of the oil.* 5089. According to Graham, the odour of essential oils is due to oxidizement, since no oil has any smell imme- diately after its distillation, in an atmosphere of carbonic acid. This may afford an explanation of a fact, which I have long noticed, that an alcoholic solution of a volatile oil has more odour than the oil when isolated. Hence the importance of keeping such substances in well closed bot- tles must be evident. 5090. The inflammation of an essential oil by concen- trated nitroso-nitric acid, has been shown. A compound results from its reaction with them, when inflammation * A small proportion of alcohol, and also of water, is liable to be held by essential oils. This may be removed by chloride of calcium. In fact, this chloride has been recommended lately to be used, in order to detect the falsification of such oils by a!- cohol. If, on adding a lump of anhydrous chloride to the oil, no change in the sur- face is perceived, the oil may be considered as free from both alcohol and moisture. 434 ORGANIC CHEMISTRY. does not ensue, which has not been well examined. With iodine some of the volatile oils have an explosive reac- tion. 5091. Volatile oils, at a high temperature, dissolve much sulphur, and a small proportion of phosphorus, and are in some degree soluble in several vegetable acids, as for in- stance, acetic, oxalic,- succinic, and the oily acids. With the exception of oil of cloves, of cinnamon, and of cedar wood, they do not form compounds when heated with alkaline or earthy bases. They are not susceptible of saponification. When triturated with sugar they are more ready to mingle with water. They are excellent solvents of the fixed oils, fat, spermaceti, wax, and generally for re- sins. Agreeably to my observations, the volatile oils, es^ pecially those containing oxygen, absorb sulphurous acid copiously; and even when washed with liquid ammonia, do not give all the elements of the acid, but retain it, proba- bly in the state of hipposulphuric acid. 5092. The density of native essential oils varies between 0.750 as in the case of that of coriander, and 1.096 in the instance of oil of sassafras. 5093. From caoutchouc, or gum elastic, an oil has been obtained of the density of .670, which is much less than that of any native oil evolved from vegetables. 5094. Volatile oils, in general, absorb six or eight times their volume of ammoniacal gas ; but the oil of lavender absorbs 47 times its volume. 5095. Oil of turpentine absorbs one-fifth of its volume of carbonic acid; nearly double its volume of carbonic oxide; twice its volume of olefiant gas; 27 per cent, of nitrous oxide, and five times its volume of cyanogen. 5096. Volatile oils are converted into resins by those metallic oxides which are readily deoxidized : also by the chlorides of tin and of antimony. What is called Star- key's soap, obtained by triturating oil of turpentine with an alkali, is a combination of a resin, produced during the process, with the alkali employed. Volatile Oils containing Sulphur as an ultimate Element. 5097. The presence of sulphur in the volatile oils, which come under the preceding designation, forms a remarkable exception to the prevailing composition of such oils. The VOLATILE OIL OF MUSTARD. 435 volatile oils of black mustard seed, of horse-radish, of onions, of asafcetida, of water pepper, of hops, and some others, contain sulphur. Volatile Oil of Mustard, C 8 H 5 NS 2 . 5098. This oil is obtained, by distillation with water, from the black mustard seed, being, it is alleged, the result of the reaction of an albuminous constituent called myro- zine, and an acid denominated rnyronic acid. Volatile oil of mustard is colourless, heavier than water, affecting the olfactory nerves so painfully as to induce tears, and pro- ducing inflammation and blisters on contact with the skin. Its boiling point is 289.4. When inflamed, it gives fumes of sulphurous acid. By distillation from hydrated oxide of lead, it is deprived of its sulphur, and resolved into ammo- nia, and a crystalline substance called sinapoline. 5099. From the formula it will be seen that this oil con- tains one atom of nitrogen, as well as two atoms of sul- phur. From the contact of this oil with ammonia in a well closed phial, a crystalline compound is formed, sup- posed to be an amiduret. Of this the formula is C 8 H 5 NS 2 + NH 2 . 5100. The remarks which were made respecting the in- expediency of treating of fixed oils in detail, apply equally in the case of the volatile oils. 5101. For information respecting their medical proper- ties, their botanical relations, and the processes of extri- cating them, where they are among the articles of the ma- teria medica, reference may be had to the United States Dispensatory. 5102. It has been mentioned that there are two classes of oils ; one containing oxygen, the other devoid of that element. The following tables of the more important vo- latile oils, with and without oxygen, are given by Kane. 56 436 ORGANIC CHEMISTRY. Volatile Oils containing Oxygen. Plant yielding the Oil. S j?-. S^- as Liquid. Boiling Point. Formula. Sp. gr. of Vapour. Cajeput .... 0.927 347 C 10 H 9 Q Lavender .... 0.896 397 C 15 H 14 O Rosemary . . . 0.897 365 C 45 R 38 Q3 Pennyroyal . . . 0.925 395 C 10 H 8 O Camphor tree . . 0.910 C 30 H 16 O Valerian .... 518 C 20 H 13 O Spearmint . . . 0.914 C 35 H 28 O Marjoram .... 0.867 354 C 50 H 40 Asarum .... C 16 H 9 O 3 Fennel .... 0.997 C 30 H 13 O a Anise C 20 H 13 O 3 Peppermint . . . 0.902 C*i H 30 O 3 Rue 0.837 446 C 28 H 38 O 3 7690 Olibanum .... 0.866 323 C 35 H 28 O 0.860 418 C 30 H 1S O 3 5094 Volatile Oils devoid of Oxygen. Plant yielding the Oil. Sp. gr. as liquid. Boiling Point. Formula. Sp. gr. as Vapour. Circular Polarizing Power. Citron . < 0.847 343 Q} c o _C Xj ID O fcT .S - c ^* 4- 80 9, right Copaiva 0.878 473 CD -^ ,** 4- 34 2, left Parsley 410 2 .a* , " S Juniper 0.839 311 "S 5 T-J O 'o ^ 3 5, left Savine . 315 O O ;/; c3 2 Cubebs . 0.929 J^ c " ^ ^ 40 l,left Black Pepper . a- +^ c X! o 0. II Bergamotte _ 73 CO 4- 29 3, right Turpentine 0.864 315 43 3, left 5103. Generally, essential oils containing oxygen may be separated into an acid and an oil destitute of oxygen, by reaction with fused hydrate of potash. Thus, from oil of valerian, valerianic acid has been obtained, and an oil which, absorbing oxygen rapidly, is converted into com- mon camphor.* Oil of cumin, by similar treatment, yields cuminic acid, which is analogous with benzoic acid, and is conjectured to have a relation to a peculiar compound ra- dical, cumyl, analogous to that which the acid last men- tioned, has to benzule or benzyl. Gerhardt and Cahours. OILS CONTAINING OXYGEN. 437 5104. The composition of all the essential oils free from oxygen, may be represented by C 5 H 4 , their formulas being multiples of these numbers. Turpentine has the formula of C 20 H 16 ; cubebs C 15 H 12 ; and the rest C 10 H 8 . 5105. Kane observes, that an examination of the tables above given, will make it appear that all essential oils con- sist of multiples of C 5 H 4 with oxygen and water. 5106. Of Oil of Turpentine. This is the cheapest, and hence by much the most used of all the volatile oils, and furnishes a good exemplification of an essential oil devoid of oxygen. When pure, it is as colourless and limpid as water. Its volatility, inflammability, hot pungent taste, and disagreeable smell, recalling that of camphor, are well known. At 72 F. its density is .86. Its boiling point is above 300. In water it is but minutely soluble, and cold alcohol only takes up about one-seventh of its bulk. When hot, it takes up a larger proportion, which is de- posited by refrigeration. As found in commerce, oil of turpentine is said to contain oxygen, whereas, in truth, it holds a resin, in which that element is a constituent, and from which it may be freed by distillation with water, or by agitation either with alcohol, with diluted sulphuric acid, or with an alcoholic solution of chloride of calcium. From the diversity of the two compounds formed with it by chlorohydric acid, there cannot be a doubt that it con- sists of two volatile oils differing but little in composi- tion. These are alleged to give rise to two different resins, found in the rosin which is associated with it in its native state.* See artificial camphor, camphene, &c. 5112, 5114. * Recently distilled, and after being carefully purified of any resinous matter, oil of turpentine has been found capable, lately, of being burned in Argand lamps of a peculiar construction, and of giving a light much more intense than that produced by fixed oil, wax, or gas. In fact, the excess of carbon which makes the flames of volatile oils too fuliginous for use, as subjected to combustion in ordinary lamps, is, in the case in point, the cause of the superior light, as it is well known that the intensity of the illumination is as the quantity of carbon oxidized in a given space. The odour of oil of turpentine, and a flocculent deposition of carbon, notwithstand- ing that there is no apparent association of such matter with the flame; also the ad- ditional danger in case of fire resulting from the presence even of a small quantity of a volatile inflammable liquid, are the great objections to the general use of this cheap and brilliant method of illumination. For streets and light-houses, where gas cannot be employed advantageously, a resort to this process may be highly expe- dient. The principles already adverted to, by which a liquid in contact with matter in a state of vaporization, will be vaporized proportionably to the tension of the vapour which it would form in vacuo at that temperature, are brought into play when a so- lution of turpentine in alcohol is burned in lamps of an appropriate form. This con- trivance is founded upon experiments made by myself more than twenty years ago, 438 ORGANIC CHEMISTRY. Of Camphor. 5107. Camphor, C 20 H 16 O 2 , or C 20 H 14 + 2HO, seems to have a relation to the volatile oils, resembling that of stea- rine or spermaceti to the fixed oils, being a species of con- crete oxidized volatile oil. It is represented as the stea- ropten of the oil of camphor. Its consistency, smell, taste, solubility in alcohol, in ether, and in the fixed and volatile oils; also its insolubility in water, and susceptibility of volatilization or evaporation in the air, are well known. Camphor fuses at 347, boils at 399.2. Its density in the solid state, as compared with that of water, 0997 ; in the state of vapour, as compared with air, 5317. 5108. By repeated distillations with anhydrous phos- phoric acid, it loses two atoms of water, and is reduced to the state of a colourless liquid hydruret of carbon, C 20 H 14 , of the density of .861 at 57, being denominated by Du- mas, its discoverer, camphogen. Camphogen is analogous to benzole or naphthaline. 5109. Liquid camphor, C 20 H 16 O 1 , is a product of the same tree as concrete camphor, and contains a more liquid portion, and less liquid portion. The former, the elaopten, differs from concrete camphor in containing only half as much oxygen. Its density is less than that of the solid camphor. In composition, the latter differs from oil of turpentine only in the presence of two atoms of oxygen; liquid camphor in the presence of one atom of the same element. 5110. An interesting account of this substance will be found in the United States Dispensatory. 5111. Other volatile oils, besides that of the camphor tree, yield stearopten analogous to camphor. Of such oils Kane gives the following table: when I used a mixture of six parts of alcohol, and one of oil of turpentine, in an Ar- gand lamp. Subsequently, however, on being consulted, I objected to the use of the contri- vance on account of the danger arising from its liability to inflame. Experience has shown, by many melancholy disasters, that this counsel was correct. OF ARTIFICIAL CAMPHOR. 439 Plant giving the Camphor. s T P-.g r .- as Liquid. Melting Point. Boiling Point. Sp. gr. of Vapour. Formula. Rose (Otto) . 77 550 CH Parsley . . 70 552 c H? 0* Iris Florentina C 4 H*O Elecampane . 108 C 7 H 5 O Asarum . . 104 530 C 18 H ll Q4 Fennel . . 1.014 68 428 Q20 H 13 Q3 Anise . . . 64 430 5680 C 30 H 13 O a Peppermint 91 406 5455 C 31 H 20 O 3 Cubebs . . . C 18 H 14 O Turpentine 1.057 302 311 C*o H ao o* " On comparing these formulae with those of the corresponding oils, it is seen that the camphors arise from very various causes ; in some cases they are isomeric with the oils, in others oxides of them, and in others hydrates; thus, the camphor of tur- pentine may be formed at will, by agitating the oil with water and then exposing it to cold; the hydrate crystallizes out in colourless prisms, sometimes of great size. " The peppermint camphor has been found to yield, by the action of reagents, a series of compounds. Thus, by the action of glacial phosphoric acid, or of oil of vitriol, a light oil was obtained, having the formula C 21 H 18 , which is termed men- then. By the action of chlorine, a thick heavy liquid is produced, C 21 H 14 Cl 6 O 2 . By nitric acid, menthen yields a heavy oily liquid, C 21 H 18 O 9 , which possesses acid properties; and with chlorine, menthen yields a syrupy yellow liquid, having the formula C^ H* CIV Artificial Camphor. 5112. If one hundred parts of oil of turpentine, refrige- rated by snow and salt, be saturated with chlorohydric acid gas, by means of an impregnating apparatus, a quan- tity of the gas, equal to about one-third of the weight of the turpentine, is absorbed. Meanwhile the turpentine is changed into a soft crystalline mass, from which, allowing it to drip for some days, about twenty parts of a colour- less acid liquor are obtained, charged with many crystals, and one hundred parts of a white, granular, crystalline sub- stance, which so much resembles camphor in odour and volatility, that it has received the same appellation. 5113. Artificial camphor is lighter than water. It does not redden litmus. It may be sublimed, but not without partial decomposition. If passed through an incandescent tube, it is resolved into its constituents. It dissolves in al- cohol, and is precipitated from it by water unchanged. Chlorine is disengaged from it by nitric acid. This sub- stance has been analyzed both by Dumas and Oppermann. According to the former chemist, it is composed of one volume of chlorohydric acid united to one volume of a 1 I 440 ORGANIC CHEMISTRY. compound, formed of ten atoms of carbon and eight of hydrogen, and consequently identical in composition with pure oil of turpentine. Of Camphene or Camphelene, and Terebene. 5114. From artificial camphor, by subjection to the distillatory process with quick-lime, an oil separates, called, by Dumas, camphene, by others, camphelene. This oil is identical in composition with pure oil of turpen- tine, and differs from it so little in properties, that were it not that the latter has a power of causing a pencil of polarized rays to turn to the left, of which power the former is devoid, one could not be distinguished from the other. The liquid from which the artificial camphor crystallizes, has the smell of camphor no less than the crystalline portion, and consists of nearly the same ultimate elements, united to chlorohydric acid. It has a relation to artificial camphor like that which the eleapten of a volatile oil bears to the stearopten. When this liquid artificial camphor is distilled with sul- phuric acid at as low a heat as possible, an oil is obtained, called terebene, which is, like camphene, devoid of the power of causing any rotation in po- larized rays. Yet either terebene or camphene, by uniting again with chlo- rohydric acid, may regenerate each the kind of artificial camphor from which it was evolved, and in this respect they differ from each other, while differing from the pure native oil as already stated. Yet, by combining with chlorine, both camphene and terebene acquire a power of causing, in polarized light, a rotation in a direction the opposite of that produced by the native oil of turpentine (4052). v Of Kreosote. 5115. This name has been given to an essential oil, to which allusion has been above made, as one of the pro- ducts of the destructive distillation of vegetable matter. It is represented as highly interesting and important, on ac- count of its efficacy as a medicine, and in preserving meat; being in fact considered as the principle to which pyrolig- neous acid and wood smoke are indebted for their antisep- tic powers, and tar-water for its medicinal virtues.* 5116. Kreosote is elaborated either from crude pyrolig- eous acid, or from wood tar, by a series of distillations, and subjection to different agents. 5117. Besides its activity in medicine, kreosote is al- leged to have energetic powers as a chemical agent. It is an oleaginous, colourless, transparent, and highly refract- ing liquid. It has the smell of crude pyroligneous acid, or of smoked meat, and its taste is caustic and burning. To * The antiseptic power of oil of cloves, and still more that of oil of cinnamon, are equal to those of kreosote, agreeably to my experiments made with meat or cream. A few drops of cinnamon oil added to a paste of gum tragacanth, will prevent, for months, the fetor which otherwise is soon acquired. OF ESSENTIAL OILS WHICH ARE HYDRURETS. 441 the touch it is a little greasy, and its consistency is similar to that of the oil of almonds. It is rather heavier than water, being of the specific gravity of 1.037. It boils at 397. 5118. Kreosote is devoid of acid or alkaline reaction. With water it forms two combinations one a solution of one part x of kreosote in four hundred of water, the other a solution of one part of water in ten of kreosote. It unites in all proportions with alcohol, ether, and naphtha, and is capable of dissolving a large quantity of iodine and phos- phorus, and likewise sulphur, especially when assisted by neat. Agreeably to Thenard, the composition of kreosote is expressed by the formula, C 14 H 9 O 2 . Of Essential Oils which are Hydrurets. 5119. Among the oils which may be called hydrurets, are the hydruret of benzule or oil of bitter almonds; an oily hydruret existing in the commercial oil of cinnamon or cassia, called hydruret of cinnamyl; the oil of spirea ulmaria or hydruret of salycyl; and the hydruret of cumyl, derived from the oil of cumin. Of the three first men- tioned oils, some account has been given in treating of their radicals ; and to the hydruret of cumyl, allusion was made in paragraph 5103. I do not, however, deem it ex- pedient to give any details here respecting any of these oils, excepting the hydruret of benzule. Of this I shall treat for the purpose of exemplification. Of the Hydruret of Benzule, or Oil of Bitter Almonds. 5120. The formula of this hydruret is O 4 H 5 O 3 -f H, or BZ + H. By distilling bitter almonds, or the leaves of cherry laurel, with water, a vola- tile product comes over, consisting of a mixture of the hydruret of benzule, of benzoic acid, of gum benzoin, and cyanhydric acid. In order to extri- cate the hydruret from this mixture, a second distillation is requisite, with the previous addition of chloride of iron, hydrate of lime, and sufficient water to liquefy the whole. Under these circumstances, the oil may be distilled, accompanied by water, which may be separated by the usual means, and subsequent agitation with chloride of calcium. 5121. Properties. This hydruret is colourless and transparent, refract- ing light strongly, being endowed with a strong odour like that of cyanhy- dric acid, and a hot taste. Its specific gravity is 1.043; its boiling point 356. It is soluble in thirty parts of water, and in alcohol in proportion. Its vapour may be transmitted through a red-hot tube without decomposi- tion. It burns with a white, though smoky flame. By absorbing two atoms of atmospheric oxygen, one to unite with an atom of hydrogen, the other to take its place, this hydruret is converted into benzoic acid. Sub- 442 ORGANIC CHEMISTRY. jected, at a high temperature in close vessels, to hydrate of potash, it forms a benzoate of that base by absorbing the oxygen, and liberating the hydro- gen of an atom of water. 5122. The hydruret of benzule undergoes no change by being in contact with aqueous solutions of caustic alkalies or earths, but, while thus situated, a few drops of cyanhydric acid will enable crystals of benzoin to be gene- rated. 5123. By contact with chlorine or bromine, the hydruret of benzule is converted into chloride or bromide, its hydrogen being simultaneously con- verted into chlorohydric or bromohydric acid, by uniting with one or the other of those elements. 5124. An iodide of benzule can be obtained by the reaction of the chlo- ride of this compound radical with the iodide of potassium ; in like manner a sulphide, by the distillatory reaction of a chloride with the sulphide of lead; and a cyanide, by substituting a cyanide of mercury and resorting to the same means. Of the Amiduret of Benzule or Benzamide, BZ NH 3 . 5125. From the preceding formula it must be evident that the compound, of which the name is above given, consists of benzule, and the compound radical, amide. 5126. This amiduret arises from the reaction of the chlorides of the same radical with dry ammonia. It is likewise evolved by the reaction of hip- puric acid with the peroxide of lead. 5127. Amiduret of benzule crystallizes in right rhomboidal pearly prisms or tables. A hot concentrated solution by refrigeration, yields a soft mass of very fine crystalline needles, which are gradually transformed into broad colourless laminae. These crystals melt at 239 into a colourless liquor, and at higher temperatures are susceptible of forming an inflammable va- pour. They are soluble either in water, alcohol, or ether. 5128. Water being present, alkalies or acids resolve this amiduret into ammonia and benzoic acid. On being heated with anhydrous baryta, a benzoate of this base is produced, with a disengagement of ammonia, much heat, and the volatile oil called benzole. Similarly treated with potassium, a cyanide of this metal results, with the evolution of an oleaginous aromatic liquid of a slightly sweet taste. The hydruret of benzule unites also with anhydrous formic acid, generating a compound acid called formobenzolic acid ; also with benzoic acid, forming x what is by Liebig termed a benzoate of the hydruret of benzule. Of Resins. 5129. Resin is now the generic name of a class of bo- dies, of which common resin or rosin is an exemplification, having had its name extended to the class in consequence of their analogy with it. On this account, English writers have latterly used the word resin, generally employing the word rosin as the name for the substance which formerly was designated either as resin or rosin. In pharmacy, rosin is also known as colophony or colophonium; especially on the continent of Europe. OF RESINS. 443 5130. Resins are found in vegetables and in the fossil state, as in the instance of amber and asphaltum ; but in every case, are considered as having been originally the products of vegetation. 5131. In vegetables, resins exist more or less in combi- nation with essential oils; and I believe them to be gene- rally produced by the reaction of such oils with oxygen. It has been mentioned that, when distilled per se, almost every volatile oil is liable to be partially converted into a resinous substance, which does not come over. It is also true, that any resin, exposed to destructive distillation, gives rise to more or less pyrogene oils of the volatile kind, as well as carburetted hydrogen, and carbonaceous deposi- tions, and residues. 5132. In many cases, as in that of the turpentine of commerce, the compound formed by the resin and the volatile oil with which it is naturally associated, is suffi- ciently liquid to flow from incisions made through the bark and sap wood. It is thus that the copious supply of turpentine found in commerce, is obtained from the long- leaved pine of the Carolinas. 5133. Another portion of resinous matter, expelled by fire, forms the tar of commerce. This contains some re- markable volatile compounds generated by heat, called paraifine, eupion, and kreosote. The former is a concrete oil, the others liquid. Tar also contains acetic acid in combination with the several peculiar resins, called pyre- tene, or pyrogene resins, by Berzelius. 5134. As the expulsion of resinous matter by the tar- producing process destroys the peculiar properties of re- sins, I believe it is not resorted to in obtaining resins in other cases. More valuable resins, which do not sponta- neously exude, are generally extracted by digesting the vegetable product containing them in alcohol. From the alcoholic solution, when it takes up other substances, the resin is precipitated by water.* * The celebrated varnish of the island of Japan exudes from the rhus vernix, which is among the forest trees of the United States, being notorious for its poison- ous influence on some persons, while to others comparatively harmless. The active principle to which its poisoning power is due, would be a worthy object of investiga- tion by any one not susceptible of the injurious effects alluded to. In the art of ja- panning in this country and in Europe, other substances are made to imitate the effect of the real Japan varnish, named from the country in which it is employed. 57 444 ORGANIC CHEMISTRY. 5135. Resins are all insoluble in water, and for the most part, directly or indirectly, soluble in alcohol, and in vola- tile and fixed oils. They cannot, like volatile oils, be dis- tilled with the aid of water. When subjected, per se, to the distillatory process, they are decomposed, as above mentioned, into carburetted hydrogen, carbon, peculiar re- sins, and volatile oils, some acids, and more or less car- bon partly in the state of lamp-black, partly in union with the other products, whence their dark or black colour. 5136. In few instances do resins assume a crystalline form. They are brittle when pure, and generally translu- cent, rarely colourless, having, commonly, various hues of yellow or brown, but sometimes green or red. There is a great resemblance in properties between resins and con- crete oils, such as suet, tallow, spermaceti. 5137. Resins are distinguished by a greater hardness and tenacity, and in being sticky to the touch instead of being greasy. Hence rosin serves to create the necessary attrition between the hair of the bow and the strings of the violin, which is an effect the opposite of that for which oil is used in machinery. In this, as well as in other re- spects, wax approaches the resins in character more than any other concrete fixed oil. But this adhesiveness is much increased by heat, so that at ordinary temperatures copal, amber, and many other resins, are not sticky. In consistency resins much resemble gums, but are distin- guished from them by insolubility in water, and solubility in fixed and volatile oils, and generally in alcohol and ether. 5138. Some resins resemble fixed oils, in containing two substances, of which one is more soluble, the other less so- luble in alcohol. This characteristic is, in some instances, displayed in their habitudes with some essential oils. Ro- sin, for instance, is said to be only partially soluble in naphtha. 5139. Resins, also, are susceptible of saponification, so far as to combine with alkaline and other bases forming salts, in which the base, being imperfectly neutralized, pos- sesses the detersive power. It is well known that rosin is a constituent of common brown soap, yet, according to Ure, it cannot enter into it advantageously beyond the proportion of a third. There is this important difference, however, in the phenomena of the reaction of fixed oils OF RESINS. 445 with bases, and that of resins, that there is no base to be expelled analogous to the oxide of glyceryl. 5140. Concentrated nitric acid and resins react, in some cases, with an explosive ignition. According to Berzelius, they dissolve in concentrated sulphuric acid, when cold, without decomposition, although when hot reciprocal de- composition ensues. I have ascertained that sulphuric acid forms, either with oil of sassafras, or with oil of cloves, resins, by which it is coloured to a miraculous de- gree, since a six-millionth part suffices to create a rosy tinge. A similar effect, in an inferior degree, ensues from the presence of oil of cloves. To the resins thus produced, I have given the names of sassarubrin and cinnarubrin. I believe in any case it will be found, that more or less resin is produced by the reaction of concentrated sulphuric acid with essential oils. In fact, such oils, to a certain extent, act as bases to this acid, diminishing the sourness of a diluted solution, and when such a solution is saturated with ammonia, a resin formed from the oil separates. 5141. Resins are soluble without alteration, either in acetic or chlorohydric acid.* 5142. Prof. F. W. Johnson has proposed to represent all resins by two general formulae, either of which contains * It appears from Unverderben's laborious investigations, that by the various use of cold or hot alcohol or ether, resins, as they are found in nature, may be resolved into various substances, differing from each other as respects readiness to combine with bases; so that he has classed them as resins strongly electro-negative, mode- rately electro-negative, feebly electro-negative, and indifferent. This author founds this diversity of designation, on their greater or less disposition to combine with ammonia, carbonate of soda, or caustic alkaline solutions. Agreeably to Johnson's Report to the British Association, for 1832, Buchner and Herberger had described some resins as having weak basic properties. Resins ex- tracted from jalap and euphorbium had each been found a compound of two resins and one acid, the other a weak base: also all drastic gum resins were considered by those chemists as similarly compounded. It is well known that all resins are electrics, and by friction become negatively electrified. According to the author last mentioned, sandarach is a mixture of three resins; copal of five; benzoin of three; guiac of two; and lac and colophony of several. When rosin or colophony is subjected to cold alcohol, of the density of 867, one portion dissolves, called alpha resin or pinic acid; while another remains, called beta resin or sylvic acid. By exposing pinic acid to distillation, another acid is generated called colopholic. Again, the solution of pinic acid may be decomposed by acetate of copper, of which the oxide precipitates with the acid, leaving an indifferent resin in solution. The white rosin, from the pinus maritina, consists of an acid, crystallizable resin, called pimaric acid. Distilled in vacuo, pimaric acid gives rise to another, called pyromaric acid. Boiled with nitric acid, pimaric yields azomaric acid. But there is no end to the variety of compounds resulting from subjecting resins to heat and va- rious solvents. It may be of some practical importance to know, that resins are not homogeneous substances, and that even the rosin of different trees may contain dif- ferent acids. 446 ORGANIC CHEMISTRY. forty atoms of carbon, while one holds from sixty to sixty- eight atoms of hydrogen, with from one to twenty of oxy- gen; the other, forty to fifty-four of hydrogen with from seven to fourteen atoms of oxygen. 5143. He infers, that the resin of scammony, C 40 H 33 O 20 , extracted from crude scammony by alcohol, contains the largest quantity of oxygen of any resin hitherto analysed; and that the resin of jalap, obtained by evaporating the al- coholic extract, and subsequent boiling in water, of which the formula is C 40 H 34 O 18 , is, as respects the quantity of contained oxygen, surpassed only by scammony. 5144. Agreeably to the same author, there is a striking relation between the formulae of the resins of ammoniac and asafcetida, the former being C 40 H 25 O 9 , the latter, C 40 H 26 O 10 , as if the one were merely a hydrate of the other. 5145. Berzelius considers our knowledge of the compo- sition of resins as yet too imperfect to justify us in placing much confidence in these suggestions of Johnson as to the grouping of all resins under two formulae as above men- tioned. Report for 1841, 171. 5146. The following list of the more important resins of commerce, with their formulae, is taken from Kane's Ele- ments, p. 969. Anime Resin Elemi Resin Fossil Copal B.* Mastic Resin Antiar Resin B. Copal Resin Birch Resin A. Mastic Resin Copaiva Resin A. Elemi Resin B. Olibanum Resin C. Sandarach Ammoniac Resin B. Asafoetida Guiacum Bdellium Resin A. Sandarach Of Wax. 5147. This word is generally used to designate the sub- stance of which bees make their honeycomb; more accu- C 40 H 33 O B. Sandarach A. Euphorbium C 40 H 32 O Asphaltene C 49 H 31 O 2 A. Olibanum CH 30 O a Labdanum C 40 H 31 O 3 Pasto Resin C 40 H 33 O 3 Sagapenum C 40 H 31 O 4 Scammony Jalap Resin C 40 H 32 O 4 Galbanum Dragon's Blood OH 30 O 6 Gamboge C 40 H 24 O 9 A. Asafcetida C 40 H 26 O 9 Acaroid Resin C 45 H 23 O 10 Opoponax B. Benzoin Resin V A. Benzoin Resin OH 31 6 C 40 H 32 8 C 48 H 3S O 7 C 40 H 32 O 8 C 40 H 33 O 20 C 40 H 34 O 20 C 40 H 20 O 19 C 40 H 30 O 13 C 40 H 22 9 * Where a native resin has been separated into two, by solvents, the letters A and B are used to distinguish one from the other. OF WAX. 447 rately called bees- wax. Other kinds of wax are found to form the pollen of flowers, the varnish on the upper sur- faces of the leaves of certain trees, and the skins of certain stone fruit ; also to be yielded by the cabbage, and in a large proportion by the berries of several species of the myrtle, myrica angustifolia, latifolia, and cerifera. 5148. Formerly bees-wax was supposed to arise from the pollen of flowers swallowed and excreted by bees; but it has been proven that the wax of bees is secreted by an organ situated on the sides of the medial line of the abdo- men of the insect. On raising the lower segments of the abdomen these sacs were observed ; also the scales, or spangles of wax arranged in pairs upon each segment. Mr. Huber ascertained that bees, while prevented from going abroad in quest of food, and fed solely on sugar, were capable of generating wax. 5149. These conclusions have been strengthened by the fact, that myrtle wax yields, by saponification, stearic, margaric, and oleic acids, and glycerine, like a true fat, while, when subjected to the same reagents, bees-wax is capable only of a partial saponification, yielding in lieu of any congener, of ethal, or of the sweet principle of oils, a substance called cerain, which differs neither in composi- tion nor properties from that portion of wax which is inso- luble in boiling alcohol. 5150. This portion has been called myricine, while the portion dissolved in the hot alcohol is called cerine. It is cerine only, that is capable even of the partial saponifica- tion to which allusion has been made. As respects this separation into cerine, and myricine, by boiling alcohol, bees-wax resembles a fat, consisting of stearine and mar- garine, while devoid of oleine; but in its chemical constitu- tion and habitudes, with bases, it resembles the resins. Wax is also destitute of the greasiness or slipperiness of fat, tending, when interposed between surfaces, to impede their sliding, rather than to facilitate it like an oil. Upon the whole I consider bees-wax as a substance intermediate between a concrete fixed oil and a resin. 5151. The yellow wax of commerce is obtained by fu- sing, and washing, the crude wax of the comb with boiling water. Yellow wax is converted into white wax by causing it to form thin ribbons by flowing while melted upon a re- volving wooden cylinder, half immersed in water, and sub- 448 ORGANIC CHEMISTRY. sequently exposing these ribbons to the solar light and the air, as in the old process for bleaching linen. The wax of the honeycomb, before being supplied with honey, is white. 5152. Pure white wax is of the specific gravity 960, 966. It is insipid and inodorous, insoluble in water, partially so- luble in boiling alcohol, and perfectly soluble in essential or fixed oils. It fuses at about 154. Its general uses are too well known to need description. Not being much act- ed on by acids, it is used to defend corks, and as cement or lute, for chemical apparatus.* Of Caoutchouc or Gum Elastic, and Caoutchoucine. 5153. Caoutchouc exudes, in the state of an emulsion, from incisions made in certain trees, and congeals in the form of the mould upon which it may be received. Like essential oils, devoid of oxygen, it consists only of carbon and hydrogen, C 8 H 7 . As respects its chemical habitudes, it might be, considered as a resin, were it not for its wonderful and peculiar elasti- city, and the mechanico-chemical property of allowing gases to get through its pores with a celerity not corresponding with the minuteness of their atomic weights. In its native state, instead of being held in solution, as re- sins are usually, by an essential oil, it is merely suspended in water, as but- ter and caseine are in milk. Faraday found in a portion of caoutchouc milk which he examined, the following ingredients: Brown bitter azotized matter, soluble in alcohol and water, and precipitable by nitrate of lead, Vegetable albumen, .... Substance soluble in water, insoluble in alcohol, Water holding a small quantity of free acid, Caoutchouc, .... 100.00 5154. Pure caoutchouc, carefully prepared from the native emulsion, is of the density of .925, being transparent and colourless, and, when in mass, yellowish white. 5155. It is utterly insoluble in water or alcohol, but soluble in pure ether (oxide of ethyl), and likewise generally in pure essential oils, especially oil * Of Cerosie. Mr. Avequin has examined the wax which covers the sugar cane, and the lower part of the leaves by which it is surrounded. It may be obtained by scraping the surfaces covered with it. In the violet variety of the plant in question, this wax is so abundant, that it Is inferred by Mr. Avequin that it might be profitably collected for the purpose of making candles. The scrapings are digested in cold al- cohol to remove impurities. Afterwards they are dissolved in boiling alcohol. This solvent being removed by distillation, the wax is isolated. This wax is slightly yellow, hard, brittle, easily reducible to powder of a bright white, fuses at 176, and burns like ordinary wax or spermaceti. It is less soluble in ether than alcohol. From boiling solutions in either solvent, it separates in pearly needle-shaped crystals by refrigeration. Mr. Avequin proposes for this wax the name cerosie, from the Greek ceros, wax. The formula of this wax is, according to analysis by Dumas, C2Q HW O'. OF CAOUTCHOUC. 449 of sassafras, cajeput, and turpentine. It does not, however, readily liquefy, but, absorbing many times its bulk of the solvent, may be liquefied after- wards by rubbing through a sieve. It is, perhaps, even more soluble in the pyrogene oils, such as naphtha, whether native or as obtained from coal, and in the peculiarly volatile oil, called caoutchoucine, which it yields itself by destructive distillation, and repeated subsequent rectifications. It has been mentioned, that this oil was lighter than any analogous native product. It is, in fact, lighter and more volatile than common ether, its density being only 670, and for its boiling point 90. From none of the volatile oils, not even caoutchoucine, have I recovered caoutchouc, without more or less de- terioration. This may be presumed to arise from a minute quantity of re- sinous matter formed at the expense of the solvent which remains with the caoutchouc. I have found a great diversity in the solubility of caoutchouc. Neither in caoutchoucine, nor in ether, have I found the ordinary bag caout- chouc to dissolve readily. It softens and swells up, but does not liquefy. But a large lump of massive caoutchouc, sent to me from London by Mr. Enderby, was readily liquefied either by the one or the other of the last mentioned solvents, and by the ether was deposited in a perfect state. I have not learned the source of the more soluble caoutchouc thus alluded to, nor have I met with any notice respecting this difference of solubility. Caoutchouc burns with an excessively fuliginous flame in atmospheric air, but in oxygen gives an intense light by the oxidation of the carbon forming the smoke (645). When fused, per se, it is converted into a tarry matter, which does not indurate by drying. This tar may be ignited by nitroso- nitric acid. 5156. Dr. Mitchell ascertained that caoutchouc bags, after soaking in a mixture of ether and alcohol of the specific gravity of from 750 to 780, or the usual officinal strength, may be inflated with air, and the material of which they consist consequently extended to various degrees of tenuity, ac- cording to the peculiar character of the variety subjected to trial. Hence it may be used to make balloons, gas bags, or sheet gum elastic, which is very useful for fillets, with which to make air-tight junctures or lutings. There is no better mode of joining a tube to the tubulure of a retort, or re- ceiver, than by tying about the tubulure the body of a small caoutchouc bag, while the tube is inserted into the neck, and carefully secured by a ligature. Fused caoutchouc is useful in some cases as a lute. It will not, however, resist fuming nitroso-nitric acid. 5157. Dr. Mitchell has made some very interesting observations respect- ing the power of gases to pass through thin membranes of caoutchouc. By some inconceivable process, gases, which are all prone, in a greater or less degree, to reciprocal intermixture, will effect this result, notwithstand- ing the interposition of caoutchouc, and the opponent influence of great pressure. 5158. When a vessel filled with atmospheric air, and having the mouth closed by a caoutchouc membrane, was introduced into a vessel of hydro- gen, this gas made its way into the vessel, until the membrane burst out- wards; but when the vessel, while similarly closed by the membrane, and replete with hydrogen, was exposed to common air, the hydrogen escaped until the membrane burst inwards. A tube, with a trumpet-shaped mouth, being bent so as to form a syphon, and the larger orifice closed by the mem- brane while full of atmospheric air, a suitable quantity of mercury was poured into the syphon, until it stood in both legs at the same height. Un- der these circumstances, when the membrane was brought into contact sue- 450 ORGANIC CHEMISTRY. cessively with different gases, they were found to enter with various degrees of celerity, as will appear from the following statement : H. M. Ammoniacal gas ----01 Sulphydric acid 2 Cyanogen 3^ Carbonic acid - 5 Protoxide of nitrogen - - - 6 Arseniuretted hydrogen - 27^ Olefiant gas - 28 Hydrogen 37 Oxygen 1 13 Carbonic oxide - - 2 40 Nitrogen 3 15 5159. The gases continued in some instances to enter until the mercury in the longer leg rose to the height of sixty inches. 5160. It is quite surprising that the atoms of ammonia should pass through the membrane with greater celerity than those of hydrogen, when each of the former consists of three of the last mentioned gas, united with one atom of nitrogen. Also that two atoms of oxygen, while associated with an atom of carbon, should permeate the membrane more speedily than an isolated atom of oxygen. 5161. It also appears from experiments made by Dr. Mitchell, and re- peated by myself, that caoutchouc is probably more highly susceptible of electric excitement, than any other organized body ; and probably is at least equal in excitability to any inorganic substance. Of Balsams. 5162. The word balsam has been used to designate na- tive solutions of resinous matter in essential oils, which, like the turpentine of commerce, exude spontaneously from trees or shrubs. 5163. Among these, however, there are some distin- guished by the presence of benzoic or cinnamic acid, or both. It is to the balsam of Peru and Tolu that this re- mark applies particularly (3060). Styrax has also been alleged to contain a minute proportion of benzoic acid, but is not included among balsams by Soubieran, and by this author the corresponding French word baume is em- ployed to designate artificial compounds of resins with an acid and volatile oil. 5164. According to Fremy, balsam of Peru consists of resinous matter, of cinnamic acid, a liquid essential oil, called cinnameine, and a crystallizable oil supposed to be a hydrate of cinnamyle (3058), called metacinnameine. 5165. Balsam of Tolu consists of resin, cinnameine, cinnamic acid, and, perhaps, metacinnameine. OF GUM-RESINS. 451 5166. Balsam of copaiva, or copaiva balsam, consists of a volatile oil, and two resins without any acid. 5167. But agreeably to the investigations of Deville, benzoic acid also exists in the two first mentioned balsams, and when the balsam of Tolu is distilled, per se over a naked fire, a volatile oil, and likewise benzoic ether, are obtained. It is suggested that the resin of the balsam is an oxide of this ether. 5168. It appears that, by reaction with caustic potash, cinnameine is resolved into cinnamic and benzoic acid in union with the alkali : an oily substance, little soluble in water, called peruvine, being simultaneously evolved. There is some analogy between this process, with its re- sults, and those of saponification. 5169. By some authors the word balsam is restricted to resiniferous liquids containing benzoic acid. It might be more reasonable to consider an acid of some kind as requisite, yet it is evident that ordinary acceptation does not justify the idea that the presence of an acid is neces- sary. Of Gum-resins. 5170. This name is applied to a class of vegetable sub- stances, which consist of a mixture of resin, gum, essential oil, and extractive matter. Opium, aloes, ammoniac, asa- fcBtida, eupJiorbium, galbanum, gamboge, myrrh, and scam- mony come under this head. 5171. As the resin and essential oil require alcohol, the gum and extractive matter water, for solution, proof spirit is the best solvent of the gum-resins. Of Opium. 5172. This complex substance contains the following proximate principles ; 1. Morphia, in the state of neutral sulphate, and super- meconate. 2. Paramorphia. 3. Pseudomorphia. 4. Codeia, in the state of supermeconate. 5. Narcotina. 6. Narceia. 7. Meconin. 8. Meconic acid, partly combined with bases. 58 452 ORGANIC CHEMISTRY. 9. Ulmin. 10. A peculiar resin. 11. A fatty oil. 12. Caoutchouc. 13. Gum. 14. Bassorin. 15. Lignin. 16. The sulphate of potash, lime, and magnesia. 5173. Of these substances, morphia, par amor pliia, pseudo- morphia, codeia, narcotina and narceia are ranked as vege- table alkalies, all having the power of neutralizing acids. Meconin is an indifferent or neutral subtance, which was announced to exist in opium in 1832, by M. Couerbe, but which is found to be identical with the crystalliz able princi- ple of M. Dublanc, jun., discovered several years before. Paramorphia, pseudomorphia, narceia, and meconin, exist in opium in very small amount. For a method of detecting opium, see meconic acid (5265). Of Bitumen, Petroleum, Naphtha, Amber, and Mineral Coal. 5174. There is in nature a gradation of substances, apparently arising from the wreck of a former world, from naphtha, which is highly volatile, to anthracite, which is extremely insusceptible of the aeriform state. Possibly the diamond may be considered as terminating the series; as it has been suggested to result from the decomposition of vegetable matter. 5175. Bitumen, in a concrete state, is exemplified by asphaltum. The coal called bituminous, owes to the presence of bitumen its capability of caking, and yielding carburetted hydrogen when ignited. Bitumen is found also in a tarry state, or more or less liquid, according to the quantity of petroleum with which it may be united. Caking coal may be considered as a compound of carbon with bitumen, and a minute portion of silex and iron, and sulphur: anthracite, as consisting of the same ingredients, substi- tuting water for bitumen, though in a lesser proportion. 5176. Petroleum, or naphtha, is the name given to an inflammable liquid which rises out of the earth like spring water, so that some wells cannot be freed from it. The name of naphtha is more properly given to a very vola- tile oil which may be obtained from petroleum by cautious distillation, prefer- ably with water. Besides more or less bitumen, by which it is discoloured to a greater or less degree; agreeably to the researches of Pellelier and Walter, petroleum comprises three volatile oils, and a species of paraffin. The names, boiling points, and formulas of the oils, are as follows: naphthol, C 3 * H 32 , boils at 384 ; naphthene, C 10 H 16 , boils at 239 ; naphtha, C 14 H 13 , boils between 185 and 194. OF ACIDS. 453 5177. Naphtha proper. The last mentioned oil may be considered as the true naphtha, being the liquid employed for the preservation of the me- tals of the alkalies. It much resembles oil of turpentine in properties and composition. Potassium, of which the specific gravity is .865, sinks readily in naphtha. 5178. During the destructive distillation of bituminous coal, a bituminous liquid, called coal tar, condenses, from which an artificial naphtha may be extricated, which is used as a solvent of caoutchouc. 5179. Seneca Oil, American Oil. Under these names two liquids are now to be met with in commerce. The former is obtained from the vicinity of the lake after which it is named ; the latter from a well in Kentucky, which was sunk for the purpose of obtaining spring water. Either yield, by distillation with water, more or less naphtha, arid contain heavier oils requiring a higher heat to bring them over by distillation. 5180. Amber is a singular fossil, which is supposed to owe its origin to vegetable matter. It is distinguished by burning with a peculiar odour, and yielding, when subjected to distillation, succinic acid, and a peculiar essen- tial oil, called oil of amber, which resembles crude naphtha in smell and other properties. The acid sublimes into the neck of the retort in crystals. Amber is insoluble both in water and alcohol. Dr. Kane suggests that it may be the turpentine of an extinct species of tree, belonging to a former geological epoch. It would seem rather to be a variety of copal, which it so much resembles in appearance and properties, as that the one may be mistaken for the other, on superficial examination. OF ACIDS. Of Acids relatively to the Proportions of Base required for their Saturation. 5181. It has long been known, that certain acids, such for instance as nitric, or chloric acid, cannot be isolated so as neither to be in unison with water, nor with any other oxide acting as a base. Until of late, however, it does not seem to have been perceived, that the water in such acids must act as a base. Now it is held, that wherever water, unless replaced by another oxide, cannot be expelled from an acid without a decomposition of the acid, or a destruc- tion of its properties, such water, while combined with the acid, must be considered as acting as a base. More- over, as when one atom of water, or other oxide, is found indispensable to the existence of an acid, that one atom has been considered as performing a basic part, so, con- sistently, when two or three atoms of water or other oxide are ascertained to be no less necessary, the two atoms, or three atoms of water or other oxide thus required, are con- sidered as acting as bases. Experience has shown that in this way, some acids require one, others two, and others 454 ORGANIC CHEMISTRY. three atoms of base, and are called accordingly monobasic, bibasic, or tribasic acids. 5182. But. it may be inquired, how is this diversity in the acids ascertained? The answer is, by ascertaining the loss of weight which they sustain, on combining with a base to saturation. Of course, the weight of the salt formed with a dry base, should be the aggregate weight of that base and the anhydrous acid. This may be found on desiccating the resulting salt. The difference between the weight of this Saline aggregate, and that of the sum of the weights of the hydrated acid and dry base, must be due to the escape of basic water. 5183. Although when water, which can be replaced by another base, is essential to the existence of an acid, it follows that it must be considered as basic ; the student ought not to infer that it cannot act as a base to acids which can exist without it. Both sulphuric and phospho- ric acid unite with water as a base, although capable of existing in the anhydrous state. This preliminary ex- planation having been given, it is hoped that the stu- dent will be prepared to understand the following state- ment, respecting the three classes of acids above men- tioned. 5184. Acids, as respects the quantity of base with which they are capable of combining, may be divided into three classes. Those requiring one equivalent of base, called monobasic; those requiring two equivalents, called bibasic; those requiring three equivalents, called tribasic acids. Water acts as a base in combining with any acid of either class, and is subject to the same laws as other bases. 5185. The compounds, hitherto called hydrated acids, are in combination with one, two, or three atoms of basic water, accordingly as they belong to the monobasic, the bibasic or tribasic class. 5186. When the hydrate of an acid of either kind is pre- sented to a base, capable of displacing water, for every atom of the new base which unites with the acid, an atom of water must be expelled. As the single salts of mono- basic acids can have only one equivalent of base, so in them there can only be one kind of base ; but in bibasic acid salts the equivalents may be of one kind only, or of two kinds ; and in tribasic acid salts, of one kind, or of OF ACIDS. 455 two, or of three kinds. In either case, water, acting as a base, is liable to be present in the same proportions as any other base, and may replace or be replaced by other bases. All that has been said of water, is also true in many cases of oxide of ammonium. 5187. Different bases, salified by the same monobasic acid, may combine to form double salts. Of course, salts having water for their base are not excepted ; but double salts thus formed with an equivalent of basic water, on ac- count of their sourness or reaction with litmus, have been called acid salts. When in such salts the water is re- placed by another base, two neutral salts result, which may be separated by crystallization, provided they differ in solubility, and crystallize separately, in forms sufficient- ly different to be distinguished. 5188. When monobasic acids are united to more than one equivalent of base, not being neutral, as bibasic or tri- basic acids are, with the same number of basic equivalents, they are called basic salts ; which conveys the idea of a salt consisting of an acid united to one or more atoms of base in excess. Yet when the atoms thus situated, are presented to another atom of the same monobasic acid, in the state of hydrate, they can displace no more than one atom of basic water; for this obvious reason, that there can be no more than one atom of basic water in union with such an acid. 5189. Salts of bibasic acids, when one of their atoms of base is water, are, from their sourness, called acid salts ; yet, substituting another base for water, does not produce a double salt. For this, two atoms of acid and four atoms of base would be requisite. 5190. Acids produced by dry distillation, are called py- rogene acids. Such acids are rarely created by subjecting monobasic acids to that process; but pyrogene acids, when thu^created, are always monobasic. 5191. Under like circumstances, bibasic acids give birth often to two new monobasic acids, as in the instance of gallic acid. 5192. By the same process, tribasic acid may give rise to three equivalents of a monobasic acid, as in the case of cyanuric acid; or they may be resolved into two monoba- sic acids, or a bibasic and a monobasic acid, as may be seen in the case of meconic acid. 456 ORGANIC CHEMISTRY. 5193. In the following table, taken from Gregory's Lie- big, the anhydrous acid is represented by R, the metallic oxybase by MO, and water by the usual symbol HO. Formula for Monobasic Salts. R + HO, hydrate of acid. R-j-MO, neutral salt. (R + MO)+MO, basic salt. (2R+2MO+MO, do. (R+MO)+2MO, do. R \ "*" > mO \ double salt with two bases. 8 R \ + \ mo' \ double salt with two bases ' 2R > 2HO . , ,. MO acidsaU ' > , $ General formulae for the salts of the bibasic acids. R -f 2 HO, hydrate of acid. R + \ J acid salt. R + 2 MO, neutral salt. R -f \ n i neutral salt with two bases. General formulae for the salts of the tribasic acids. R -f 3HO, hydrate of the acid. f OTJQ i R -f J ,-^ > salt with one atom of a fixed base. R -f- 5 9T\1O i sa ^ w ^ tb two atoms f a fi xe( ^ base. R + 3MO, tribasic salt. HO ) R -f < MO > salt with two different fixed bases. mO, ^ Of Acetic Acid. 5194. Acetic acid is monobasic, being a hydrated triox- ide of acetyl (3093), as may be seen from its formula, C 4 H 3 O 3 +HO. 5195. As the cause of the sourness in fermented liquors, and various products of vegetation, this acid, having been OF ACETIC ACID. 457 the first to attract human observation, has given a name to the whole class of acids; though at this time many of the compounds recognised as acids, are devoid of the attri- bute on which the general name is founded. Acetic acid is the only valuable ingredient in vinegar, causing the sour- ness indicated by its name, which differs but little from vin aigre, the words expressive of sour wine in French. 5196. This acid occurs in nature in many products of the vegetable and animal organization: as for instance; in the black elder (sumbucus niger); the pleurix dactilifera, and rhus tiphinus; in sweat, urine, milk, and the fluids of the stomach. 5197. It had long been observed that the fermented li- quors containing the most spirit made the strongest vine- gars. Although pure alcohol is not liable to be acidified per se, when diluted with water holding fermentable sub- stances, it is readily converted into vinegar. For this purpose each atom requires four of oxygen. Two atoms of this element are requisite to remove two of hydrogen, by which ethyl (3069), the radical of the alcohol, is changed into acetyl (3093), the radical of acetic acid. At the same time, two atoms of oxygen are required to be added to the one atom previously in union with the ethyl, to make the three required for acetic acid, which is a trioxide of acetyl. The formula of alcohol is C 4 H 5 O+HO. If to this we add four atoms of oxygen, we have C 4 H 5 O 5 +HO, which gives the formula of hydrated acetic acid = C 4 H 3 O 3 HO+2HO in excess.* See paragraph 3094 and note. 5198. I shall defer the exposition of the phenomena, causes, and circumstances, on which the conversion of vi- nous liquids into vinegar is dependent, until I treat of fer- mentation. Practically, every body has a general idea of the mode in which wine, cider, or beer, vinegar, is obtained. 5199. Ajcetic acid is also a product of the destructive distillation*of wood. In that case it forms what has been * Liebig alleges that a strong and agreeable vinegar may be made by exposing to the air for some weeks in a warm situation, the following mixture; 100 parts water, 13 brandy, 4 parts honey, and 1 crude tartar. Of course, one part cream of tartar might be substituted for the crude tartar. The acetification of mixtures of vegetable juices with spirit, has been very much expedited, of late years, by a high temperature, and allowing the liquor to drop from a tube through holes like those of a colander, on beach wood shavings. Respecting this, and other processes for the generation of acetic acid, much information will be found in Ure's Dictionary of Arts and Manufactures; also in Liebig's Traite de Chymie Organique, 386. 458 ORGANIC CHEMISTRY. called pyroligneous acid, which contains various other sub- stances. From these the acid is extricated by combining it with a base, and subsequent distillatory decomposition of the resulting salt by sulphuric acid, the impure acetate having been first cautiously fused to get rid of impurities. 5200. The acetic acid, thus obtained, is much diluted with water, from which it may be freed by digestion with anhy- drous sulphate of soda, and subsequent distillation. In this way, according to Liebig, a sufficient degree of concentra- tion may be attained to render the acid crystallizable. As in the case of other organic, acids, that in question cannot exist excepting in combination with basic water, or some other base. 5201. The distillation of dry acetate of copper, has been long made the means of evolving the contained acid, in a concentrated state. Resort has also been had to the de- composition of the dry acetate of soda, or lead, with equi- valent portions of concentrated sulphuric acid. 1. Accord- ing to Liebig, the proportions should be, 3 acetate of soda, with 9.7 acid : or, 3 acetate of lead, with 8 acid. 5202. Pure hydrated acetic acid crystallizes in shining, transparent lamellar, or tabular, crystals. At the tempera- ture of 63 nearly, these crystals fuse into a limpid liquid, of the density of 1.063; of which the pungent and distin- guishing smell and taste may be inferred, from the inferior effect of strong vinegar. In its concentrated form, as it is capable of blistering the skin, its action upon the tongue must be insupportable. Like other liquids greedy of wa- ter, it produces fumes on contact with the aqueous vapour of the atmosphere. It boils at 142, and unites in all pro- portions with water, alcohol, ether, many essential oils, camphor, and some resins. When in the state of vapour, it is capable of burning with a blue flame, and being re- solved into water and carbonic acid. 5203. It has been mentioned, that, when liquid, crystal- lizable acetic acid is denser than water. To a certain ex- tent, by admixture with this liquid, a condensation ensues; but a further addition of water causes the opposite change. Equal parts by weight have the same density as the pure hydrate. The highest density attainable is 107, indicating the presence of three atoms of water, and one of anhydrous acid; or by weight, 772 acid, and 228 water. OF ACETIC ACID. 459 5204. Allusion has been made to the process by which platinum black causes the acetification of alcohol* (1607). 5205. Of Pyroligneous Acid. The process by which charcoal is obtained by the destructive distillation of wood, has been mentioned as one by which acetic acid is generated. Thus produced, it is generally known as py- roligneous acid, being very much disguised by impurities. In fact, pyroligneous acid so called, contains beside the acetic acid, paraffine, eupione, kreosote, and the pyrogene, resinous matter, called pyretene by Berzelius. 5206. When the process is performed with a suitable apparatus, this acid is collected. Pyroligneous acid may be considered as the matter of wood smoke in the liquid form; and when applied in this state to salted meat, is at least as efficacious as when employed as smoke in the usual way. The process of the smoke-house is less sus- ceptible of precision, and is liable to produce an injurious rise of temperature. 5207. Of the Acetates. These salts are soluble, with very few exceptions. Only two are cited as insoluble by Liebig; those of molybdenum and tungsten. The ace- tates of silver and of the protoxide of mercury, are soluble only to a very small extent. All the acetates smell of ace- tic acid, on the affusion of sulphuric acid. Those formed with oxides of the metals proper, yield their acid on the application of heat, with a partial decomposition. When the base is a fixed alkali or alkaline earth, they are re- solved into carbonates and acetone (3098). 5208. When in diluted aqueous solution, especially when the base is in excess, any alkaline acetate undergoes a partial resolution into a carbonate. 5209. Of course, any of the acetates may be formed by the saturation of the acid with the proper base. In some cases, they may be obtained advantageously by double de- * Dr. Ure alleges, that by means of twenty to thirty pounds of platinum powder, which does not waste, \ve may transform, daily, three hundred pounds of bad spirits into the finest vinegar. For this purpose, platinum black may be made, by fusing platina ore with twice its weight of zinc; pulverizing the resulting alloy, and subjecting it successively to diluted sulphuric and diluted nitric acid, the latter with heat. The zinc being dis- solved or oxidized, the residual powder, after washing with a solution of potash and water, is fit for the purpose in question. The process has been conducted in a wooden box having a capacity of twelve cu- bic feet. 59 460 ORGANIC CHEMISTRY. composition, as illustrated in the case of sulphate of zinc, and acetate of lead, which when added together in a state of solution, form sulphate of lead and acetate of zinc. Formerly, the acetate of potash was known as foliated earth of tartar, acetate of ammonia as spirit of minde- rerus. 5210. Of Acetate of Ammonia, or Spirit of Mindererus. This salt may be obtained by distilling sal ammoniac with acetate of soda, when, after the escape of some ammonia, the acetate comes over liquefied, and crystallizes in trans- parent, colourless needles. 5211. This acetate has an acid reaction, is deliquescent, and soluble in all proportions in water and alcohol. Of the acetates of lead some mention has already been made. (1740.) 5212. Sugar of lead, according to Liebig, contains an equal number of atoms of acid and base. Besides this, there is sesguibasic acetate, consisting of two atoms of acid, with three atoms of base. 5213. Tribasic acetate, consisting of one atom of acid, with three atoms of base. 5214. Sexbasic acetate, holding one atom of acid to six atoms of base. Sugar of lead is, of course, the neutral acetate. Of Lactic Acid. 5215. This acid is that which exists in sour milk, whence its name from lac, the latin for milk. It has lately been shown to be generally the product of a peculiar fermenta- tion, called viscous, to which the juices of plants, contain- ing albumen, are spontaneously liable, when yeast is not added, at a temperature between 86 and 104. This fer- mentation differs from the vinous, in being accompanied by the evolution of inflammable gases, as well as carbonic acid, and in not being productive of alcohol, but of lactic acid and manna sugar, or mannite (4074). It is obtained from sour milk by saturation with soda, and decomposing the resulting lactate by sulphuric acid. By a previous ad- dition of lactin, in the ratio of eight ounces to eight pints of the milk, the quantity of acid produced may be advan- tageously increased. 5216. Lactic acid is monobasic, and as it exists in the anhydrous salt which it forms with zinc, consists of C 6 H 5 O 5 . OF CITRIC OR MALIC ACID. 461 Its composition is remarkable, since, as the hydrogen and oxygen which it contains exist in the proportion for forming water, it might be represented as a hydrate of carbon; a composition which usually belongs to bodies, which, as it respects basic and acid properties, act indif- ferently. When in its most concentrated form, it appears as a sour syrup, incapable of crystallization. On being heated to 482, it is decomposed, yielding, among other products, a large amount of a crystallized acid sublimate. As this consists of C 6 H 4 O 4 , it was for some time treated as anhydrous lactic acid; but as the anhydrous lactate of zinc is said to contain H 5 O 5 , this sublimate must be re- garded as a distinct acid. By boiling in water, the new acid combines with an atom of oxygen and an atom of hy- drogen, and is consequently reconverted into lactic acid. Of Citric and Malic Acid. 5217. The name of citric acid indicates its origin.* It exists in the lime and lemon, in union with mucilage and malic acid. Its combination with mucilage is so intimate as to render it impossible to separate the acid without first uniting it with some other matter. Alcohol combines with the acid, and precipitates the mucilage. Yet, the al- coholic solution, thus obtained, does not yield crystals, even after evaporation, re-solution in water, and evapora- ting the water. 5218. The most efficient mode of obtaining this acid pure, is to saturate the juice of lemons with chalk or whiting, and afterwards to decompose the citrate of lime thus formed, by sulphuric acid, duly diluted. The citric acid may be obtained in crystals, from the supernatant li- quid, by evaporation. 5219. Citric acid is crystallizable. Its taste is intense- ly acid when concentrated, but agreeably sour when dilute. 5220. It is a tribasic acid; its formula, when dried at 212, being represented by C 12 H 5 O 11 + 3HO. The atoms of water are essential to the composition of the acid in its free state, and cannot be removed unless by substitution of an equivalent number of atoms of some other base. 5221. Malic acid derives its name from the apple, as * From thp fruit of the genus citrus, including the orange, citron, lemon, lime, and shaddock. 462 ORGANIC CHEMISTRY. in this fruit it predominates, as well as in gooseberries, currants, and other similar fruits. It may be had pure by saturating lime with apple juice, and decomposing the ma- late of lime by sulphuric acid. 5222. Professor Wm. Rogers, of the University of Vir- ginia, has ascertained that this acid abounds in different species of sumach, in the state of bimalate of lime. Malic acid is bibasic, its formula being C 5 H 4 O 8 + 2HO. 5223. Malic and citric acids afford very good examples of the operation of a law, to which a great many of the vegetable acids are subjected. At a tem- perature a little above that at which they melt, they severally yield new acids* That yielded by citric'acid, is identical with the acid found in the aconitum napellus, and also the various species of equisitum. Hence, it has received the name of aconitic or equisitic acid. Whether obtained from citric acid by heat, or from either of its other sources, it exists in the form of white crystals, soluble in water, and sour in taste. The acid into which malic acid is changed, under similar circumstances, is also found in nature in the Iceland moss, and in the fumaria officinalis. Hence it has been called fu- maric acid, although Pelouze, who first obtained it from malic acid by heat, .called it paramalic acid. Both of these acids differ from the citric and malic acid, from which they are produced, only in having lost the elements of two atoms of water. 5224. When either of the acids thus obtained, by heating citric or malic acid, is exposed to a higher temperature, a further change takes place, and volatile acids are formed, fumaric acid yielding malic, and aconitic producing itaconic acid. The former would seem to be formed by a mere transposition of the elements of water present, which appear as two atoms of water of crys- tallization, instead of entering as before as two basic atoms into the integral composition of the acid. A farther application of heat converts itaconic into citraconic acid ; while malleic acid, if kept in a state of fusion for a length of time, reverts to the condition of furnaric acid. 5225. It must be observed, that if citric or malic acid be heated, without keeping them at the temperatures necessary for the formation of the acid compounds which they respectively produce, the result will be a mixture in the one case of fumaric acid and malic acid, in the other, of aconitic, ita- conic and citraconic acids. Of Tartaric Acid, and Paratartaric or Racemic Acid. 5226. Tartaric acid is found in many vegetables. It is named from tartar, an appellation given to a deposition from wine, which contains this acid united with potash arid water. This tartrate, when freed from impurities, is known officinally under the name of cream of tartar. When to twenty-four parts of this salt, thirteen of carbonate of soda are added, sal Rochelle, a tartrate of potash and soda, is produced ; and in like manner, tartar emetic, by replacing the basic water by the sesquioxide of antimony. Another pharmaceutical compound, called tartarized iron, is pro- OP TARTARIC ACID. 463 duced by replacing the water of cream of tartar by iron, which is taken up in the state of protoxide, but becomes, by exposure, more or less sesquioxidized. 5227. Tartaric acid is procured from cream of tartar in fine crystals, by adding chalk until effervescence ceases, and decomposing the precipitate by diluted sulphuric acid. The neutral tartrate of potash left, may be decomposed by quicklime or chloride of calcium, and the resulting tartrate of lime will yield the acid in the same way as the analo- gous tartrate, obtained in the first instance by the addition of chalk. 5228. Tartaric acid is extremely sour, and reddens lit- mus. It is bibasic, its formula being C 8 H 4 O JO + 2HO. In consequence of this bibasic character, the salts which it forms with one atom of a fixed base are sour, have an acid reaction, and require the presence of an atom of basic water. Thus the salt heretofore described as the bitar- trate of potash, must now be considered as the tartrate of potash and water, since it consists of one atom of tartaric acid, one atom of potash, and an atom of basic water. 5229. Of Paratartaric or Racemic Acid. A manufac- turer of Thann, in Germany, in preparing tartaric acid from cream of tartar, which had been deposited from the wine of that country, discovered an acid differing from that which it was his object to procure, and which he sup- posed to be the oxalic. Gay-Lussac subsequently proved, that while possessed of peculiar qualities, its equivalent was the same as that of tartaric acid. By Berzelius it was afterwards shown to be isomeric with this last men- tioned acid, and he has consequently named it paratar- taric acid. The appellation of racemic, has also been ap- plied to it. Paratartaric acid crystallizes in a different form from tartaric acid proper. It is likewise less solu- ble. 5230. The action of heat on tartaric acid is strikingly peculiar. At a temperature merely sufficient to produce fusion, two atoms of the acid give off one of the four atoms of the basic water combined with them, losing at the same time one fourth of their saturating power, and causing the acid to become sesquibasic, so that two atoms of it saturate only three of base. The name of tartralic has been applied to the acid in this state. 5231. A still further application of heat removes another half atom of water and produces tartrelic acid, which is monobasic, saturating only one atom of base, and requiring in the free state the presence of but one atom of water. A still higher temperature removes all basic water, and leaves a porous white mass, insoluble in water, and hence no longer sour or capable 464 ORGANIC CHEMISTRY. of reddening litmus. The composition of this body is C 8 H 4 O 10 . Conse- quently, it is identical with that of tartaric acid freed from its basic water, as it exists for instance in the bibasic tartrate of lead. If left long in con- tact with the water, this insoluble compound gradually takes up two atoms of the oxide of hydrogen, and becomes the ordinary soluble bibasic tartaric acid. It has been considered, that the absence of sourness, in this only in- stance of an isolated anhydrous organic acid, is favourable to the idea that oxacids are hydrurets of compound radicals owing their acid reaction to hydrogen; but it should be recollected, that the absence of this action is an invariable consequence of insolubility. No insoluble hydruret of which there are instances among the oils or etherial compounds is sour. Nor is it that portion of water which enters the tartaric acid as a base, and on the hydrogen of which the hypothesis relies, which confers either sourness or the capacity for acid reaction with vegetable colours. Independently of moisture, the gaseous hydracids, erroneously so called, have, I believe, no such properties. 5232. Of Liquid and Solid Pyrotartaric Acid. By destructive distil- lation, tartaric acid yields two acids, to which the preceding appellations have been given. Liquid pyrotartaric acid forms a monobasic ether, and various salts. Its formula is C 8 H 3 O 5 . Solid pyrotartaric acid is gene- rated in small proportion, during the destructive distillation of tartaric acid ; but is yielded more- copiously by subjecting cream of tartar to that process. Graham, 948. Of Guiacine, or Guiacinic Acid. 5233. In the Journale de Pharmacie, for 1842, p. 386, notice is given by J. Pelletier, of the results of an investigation, which, though it had not been completed, enabled him to allege that the peculiar principle of gum guiacum, which he calls guayacine, in English guiacine, may be isolated by either of two processes. According to one, an alcoholic solution of acetate of lead is to be added in successive portions to a tincture of the resin, reject- ing the latter portions of the precipitates formed. The compound thus pro- cured, is to be well washed with water first, and afterwards with alcohol. Then being suspended in water, is to be exposed to sulphydric acid, by which the lead is precipitated as a sulphide. The guiacine is then taken up by alcohol. 5234. According to the other process, hydrate of lime is added to the tincture, by which means a compound, of the guiacine and lime, is obtained. From this the guiacine may be easily extricated. 5235. Guiacine has, in a high degree, the property of becoming blue by absorbing oxygen, and, after being thus coloured, may be restored to its previous state by substances greedy of oxygen, such as sulphydric or sul- phurous acid, protoxide of iron, or protochloride of tin. Re-exposure to the air restores the blue colour. 5236. Moist chlorine, or an aqueous solution of this gas, turns guiacine blue; but an excess renders it green, and yellow, successively. From the last mentioned state it cannot be restored, having undergone a chemical change. 5237. Notwithstanding the property of combining with bases, Mr. Pelle- tier hesitated to designate it as an acid, but in this, as it was found to com- bine with bases, I consider him as misjudging. The analogy between this resin and indigd, as respects changes of Colour, must strike every one ac- quainted with the facts. OF TANNIC ACID. 465 5238. I presume in English the principle which he has isolated, will be called guaicine ; or if it be an acid, as from the account given, it evidently ought to be considered, the name will be guaicinic acid. Of Tannic Acid. 5239. From its formula, C 18 H 5 O 9 + 3HO, it may be seen that the tannic acid is tribasic. 5240. The art of converting the hides or skins of ani- mals into leather, by soaking them in infusions of the bark of oak and other trees, had long been practised. Subse- quently it was ascertained that this change arose from a che- mical combination ensuing between the gelatin of the skin or hide, and a vegetable principle called tannin, from its ef- ficiency in the process of tanning abovementioned. Ber- zelius first treated of tannin as an acid. This view being adopted, the principle is now universally designated as tannic acid. It is peculiarly abundant in oak galls, giving to an infusion of them the property of causing, with iron, an ink colour, whence its use as an ingredient of common writing ink. 5241. Tannic acid is likewise found in a great number of vegetables, generally in their bark or roots, but not un- frequently in their leaves and seeds, and even in their flow- ers and fruits, before they have reached maturity. It is, in fact, the most frequent cause of astringency in vegetable products. 5242. It may be procured, according to Mr. Pelouze, in a state of purity, by introducing powdered galls into a ves- sel, with a body and pipe resembling that of a funnel, but contracted above into a neck like that of a bottle. The pipe of this vessel should be furnished with a cock, and must be made to descend into a tincture bottle through the mouth. The galls are then to be covered with sul- phuric ether, of the officinal strength, and the mouth of the vessel being corked, they are to be left in contact with the ether for several hours. The liquid being then allowed to descend into the bottle, will be found to separate into two portions, of which the heaviest is a solution of tannic acid. From this solution the acid may be obtained in the solid form by washing with ether, and evaporation, in vacuo, over sulphuric acid. Thus obtained, it is inodorous, as- tringent, yellowish white, and somewhat crystalline. 5243. The oxides of the following metals form insoluble 466 ORGANIC CHEMISTRY. tannates, and hence yield precipitates with tannic acid, or an infusion of galls. The colours of these precipitates are as follows : The precipitate formed with lead or antimony, white. With tin, nickel, cobalt, silver, various shades of yellow. With tantalum or bismuth, orange. With titanium, blood red. With platinum, green. With chrome, molybdenum, uranium, and gold, brown. With osmium and sesquioxide of iron, deep purple, blue, or ink colour. 5244. On account of the insolubility of the tannate of antimony, an infusion of galls, or of oak bark, is an anti- dote for tartar emetic and other antimonial preparations. 5245. Tannic acid has also been found a test for, and precipitant of, the organic alkalies, and must be more or less an antidote for their poisonous influence. 5246. The aqueous solution of tannic acid reddens lit- mus. It does not affect solutions of the protoxide of iron; and the intense colour produced as abovementioned, with the sesquioxide, may be removed by reagents, which re- duce the iron to the state of protoxide, as already illus- trated (1817). 5247. Ink is best made with the green sulphate of iron, because, so long as the iron is not sesquioxidized, remain- ing in solution, it can penetrate the paper better ; and it soon peroxidizes, and consequently blackens, by exposure to the atmospheric oxygen. (Ure.) 5248. By a piece of raw hide, pure tannic acid may, in a few hours, be taken up from a solution so completely, that if no gallic acid be present, the liquid will not be af- fected by a solution of sesquioxide of iron. 5249. According to Graham, tannic acid precipitates a solution of starch and albumen, and is capable of com- bining with animal fibrin. 5250. Of Artificial Tannin. A substance resembling tannic acid in many of its properties, and called, gene- rally, artificial tannin, is formed during the action of ni- tric or sulphuric acid on a great variety of vegetable sub- stances. One variety of this tannin is formed by the reac- tion of nitric acid with charcoal. OF GALLIC ACID. 467 Of Gallic Acid. 5251. Formula of the dry acid, C 7 HO 3 2HO. When crystallized, one additional atom of water is present. 5252. This acid and tannic acid appear to be almost always more or less associated; so that they are generally both present, where either is found. This is now explained by the fact, that tannic acid is liable to be converted into gallic acid spontaneously. 5253. Agreeably to one, of the processes recommended for procuring the last mentioned acid, nut galls, made into a paste with water, are to be exposed to the air for seve- ral weeks at the temperature of 80 nearly, water being supplied so as to compensate for evaporation. The re- sulting mass is to be subjected to boiling water, and the solution thus obtained being filtered, the gallic acid sepa- rates in the crystalline form. It is rendered quite pure by re-solution, digestion with animal charcoal, and re-crystal- lization. 5254. If the precipitate, obtained by adding sulphuric acid to a concentrated extract of galls, be washed with a small quantity of water, and then dissolved by gradually adding it to a boiling solution of one part of sulphuric acid in two of water, gallic acid is generated, and, by refrige- ration, separates from the liquid in crystals. The impure acid thus isolated, may be purified partially by re-solution and crystallization; or more thoroughly by adding to a solution of it acetate of lead, and decomposing the result- ing insoluble gallate of the protoxide of lead, by sulphydric acid (899). By these means the lead is converted into a sulphide, which separates this metal, and much colouring matter, simultaneously; the acid remaining dissolved. Graham, 941. 5255. Again, if tannic acid be subjected, for a few mi- nutes, to a solution of caustic potash, on the addition of sulphuric acid in excess, crystals of gallic acid will be co- piously formed on the cooling of the liquid. Kane, 1010. 5256. Gallic acid crystallizes from a hot solution in thin silky needles, which, for solution, require 100 parts of cold water, although, when boiling, three parts are sufficient. It is very soluble in alcohol, and sparingly soluble in ether. Although it is productive of the same changes in solutions 60 468 ORGANIC CHEMISTRY. of sesquioxide of iron as tannic acid, it differs from it in not causing any precipitate in solutions of gelatine. 5257. It would appear doubtful whether this acid exists ready formed in nature, or whether it be not always a pro- duct of the oxidation, or partial decomposition of tannic acid. It has been stated, that the exposure of the latter to the air, or boiling it with an excess of alkali, without the presence of the atmosphere, produces this change; and that it may also be effected by means of sulphuric acid. 5258. On the one hand it has been observed, that three atoms of tannic acid contain the elements of six atoms of gallic acid, and one of grape sugar; and on the other, that the absorption of eight atoms of oxygen would convert an atom of tannic acid into four atoms of carbonic acid and two of crystallized gallic acid. As, according to Bracon- not, alcohol and carbonic acid have been evolved from nut- galls during their fermentation, it seems possible that tan- nic acid may be produced, according to circumstances, either by fermentation, or by the oxidation of the princi- ples present in nut-galls. Indeed, tannic acid itself would appear, from the nature of the sources from which it is obtained, to be, in many instances, the result of a gradual decay of other principles in plants; and when gallic acid, either in its free state, or as it exists in the gallates, is ex- posed to the air, it' undergoes a still further change into carbonic acid, and a brown vegetable substance. Hence it may be conjectured, that both of the acids in question are the products of different stages of one continued trans- formation. 5259. If gallic acid be heated to about 400, it is decomposed into car- bonic acid, and a new acid which sublimes in brilliant white plates. This acid has received the name of pyrogallic, and is soluble in water, alcohol, and ether. If, on the contrary, the heat be raised above 450, an insoluble black mass remains in the retort, to which, from its combining with alka- lies, and its colour, the name of melangallic acid has been given. These results are only worthy of notice as forming part of a series of transforma- tions which most of the organic acids undergo through the application of heat. 5260. An acid, called the elagic, is frequently produced during that ex- posure of galls to the air, which gives rise to the formation of gallic acid. There are several species of vegetable products in which acids, resembling the gallic and tannic acids, though not identical with them, have been dis- covered. Thus, in the bark of the various species of cinchona, combined with quinia or cinchona, are found two acids, the cinchonic and cinchona- OF MECONIC ACID. 469 tannic, whose physical properties stand in very nearly the same relation to each other as that borne by gallic and tannic acid ; and in catechu, an ex- tract obtained from the mimosa catechu, there have been discovered two acids, the catechuic and the catechutannic, of which nearly the same state- ment may be made. It does not appear, however, that in either case one of them has the property of being converted into the other, as is the case with tannic and gallic acids. Berzelius, however, is of the opinion, that all the forms of tannic acid found in plants are identical in composition, but modified by association with other matter. Of Meconic Acid. 5261. Formula,C 14 HO n +3HO; when crystallized + 6HO. Meconic acid is tribasic. 5262. When a solution of acetate of lead is added to an infusion of opium, a precipitate is obtained, consisting of meconate of lead. From this the lead may be precipitated as a sulphide by means of sulphydric acid, and a solu- tion of the liberated meconic acid obtained by filtration. This acid exists in opium, combined with morphia and codeia. 5263. With solutions of the sesquioxide of iron, meconic acid produces an intense red colour; with protoxide of lead an insoluble precipitate. It is to this affinity, for oxidized lead, that we owe the process, above described, for pro- curing this acid. 5264. Meconic acid produces a taste, at first sour, and subsequently bitter, and reddens litmus paper. Being a tribasic acid, it forms three classes of salts, in which the water present may be replaced, partially or entirely, by one, two, or three atoms of base. Like other organic acids which have been described, meconic acid is converted by heat into another acid, the komenic, carbonic acid being evolved; and as this komenic acid cannot be volatilized, it is, at a higher temperature, converted into pyromeconic acid, which may be sublimed without further change. Each of these transformations is accompanied by the loss of an atom of basic water, and a diminished capacity of saturating bases. Of a Method of detecting the Presence of Opium. 5265. The property which meconic acid has of precipi- tating with lead, and of producing a red colour with iron, may enable us to detect opium, when present in a very small quantity in solution. 470 ORGANIC CHEMISTRY. 5266. If ten drops of the tincture of opium, commonly called laudanum, be mingled with half a gallon of water, on adding a few drops of subacetate of lead, there will be a precipitation which, at the end of a few hours, will be per- ceptible in flocks. The descent of these flocks may be ac- celerated by detaching them gently from the sides of the recipient with a glass rod. The vessel should be conical, so as to concentrate them during their descent. After they are collected at the bottom of the vessel, about 30 drops of the red sulphate of iron, and an equivalent portion of sulphuric acid should be introduced among them by means of a small glass tube. The presence of the me- conic acid will be rendered evident by the redness which ensues. 5267. When a red colour is produced by the means here described, it is probable that opium is present; as me- conic acid is found only in that drug, and having no active qualities, is not used separately from it in any pharmaceu- tical preparation. 5268. It may be proper to mention, that sulphocyanhy- dric acid produces, with the sesquioxide of iron, a colour resembling that produced by meconic acid. Of the Acids formed from Sugar. 5269. Cane sugar may be made to combine, as sugar, with the alkaline earths, and with some of the metallic oxides, though not with the alkalies. In these compounds the sugar exists unchanged, but united to the base by an affinity so feeble, that it may be displaced by carbonic acid. 5270. Nevertheless, if sugar be kept a long time dissolved in an alkaline solution, it undergoes a transformation into a real acid, the glucic acid, which has a sour taste when free, and combines with bases to form salts. In this acid, as in lactic acid, the oxygen and hydrogen are present in the proportion for forming water; and the only change which sugar experiences by conversion into glucic acid, is the loss of several atoms of water. The formula for glucic acid would appear to be C 12 H 8 O 8 . 5271. If heat be applied to a solution of sugar with an alkaline base, melassic acid is produced either from the sugar directly, or from the glucic acid. It is said to consist of C 24 H 12 O 10 , so that in forming it, sugar parts not only with water, but also with oxygen. 5272. By the reaction of diluted nitric acid with sugar, a crystallizable acid of a strong sour taste is produced. It was at first supposed to be malic acid, but was afterwards distinguished by the name of oxalhydric. It is now called saccharic acid. Its formula is C 13 H 5 O 14 5HO. The five atoms of water are essential to the composition of the acid in what is called the free state. When it is united to other bases, the water is replaced, ^wholly or in part, by a corresponding number of atoms of base. The an- hydrous salt which it forms with lead, consists of C 12 H 5 O 11 + 5PbO ; OF FORMIC ACID. 471 and by its union with the oxide of that metal, it forms three other salts, in which we find C 13 H 5 O 11 combined, respectively, with 3PbO + 2HO, 2PbO + 3HO, and PbO + 4HO. These facts respecting the composition of the saccharates are instructive, as furnishing support to the theory of poly- basic acids ; since, if we do not have recourse to that theory, we must sup- pose the existence of a distinct acid in each of the salts above mentioned, and that one of them has the property of combining with five atoms of base, and not with any smaller quantity. 5273. When lactin (sugar of milk, 4070) is subjected to the action of diluted nitric acid, mucic acid is produced. It may also be obtained by substituting gum, or mannite, for the sugar of milk. It exists as a crystal- line powder of difficult solubility, and a feebly acid taste. Its formula is Of Formic Acid. 5274. It is inferred, that between formic acid, formyl (4019), and methyl (4016), the same relation exists as be- tween acetic acid, acetyl, and ethyl; and also that the part performed by alcohol, the hydrated oxide of ethyl, in the one case, is performed by pyroxylic spirit, the hydrated oxide of methyl in the other. Either the methylic, or ethy- lic alcohol, by losing two atoms of hydrogen, and acquiring two of oxygen, are converted, the one into acetic, the other into formic acid. Moreover, the same catalytic agent, pla- tinum sponge, or black, may in either case be competent to induce the requisite reaction with atmospheric oxygen. The features which are wanting to complete the resem- blance, are congeners severally of aldehyde, C 4 H 3 O + HO, and acetous acid, C 4 H 3 O 2 + HO. To correspond with these compounds, no hydrated oxide of formyl, nor formous acid, are known. 5275. To render this statement more intelligible, the following formulae are subjoined. Methyl, C 2 H 3 ; formyl, C 2 H; anhydrous formic acid, C 2 HO 3 . To form the hy- drated acid, one atom of water, HO, must be added. 5276. Formic acid was originally obtained from ants. It appears to exist in them naturally. 5277. This acid may be obtained by adding to one part of sugar in an alembic, three parts of well pulverized peroxide of manganese, and three parts of sulphuric acid diluted with its weight of water. The acid should be added in three successive portions. At first, the efferves- cence is so great as to require the vessel to have fifteen times the capacity which would be necessary to contain the material when quiescent. The formic acid associated 472 ORGANIC CHEMISTRY. with formic ether, is brought over by distillation. It may be saturated with chalk or an alkali, and the resulting formiate decomposed and isolated by distillation with ten parts by weight of sulphuric acid, diluted with four of water. 5278. According to the late Professor Emmet, the pre- sence of peroxide of manganese in this process is unneces- sary. Agreeably to his observations, the conversion of many vegetable substances into formic acid, among others maize, may be effected by any of those agents which would effect the evolution of ether from alcohol. 5279. From the investigations of Dobereiner, it ap- pears that formic acid is an excellent reagent for separat- ing the noble metals from solutions in which they are in- termingled with other metals proper. If a solution con- taining one or more noble metals, be elevated nearly to the temperature of ebullition, on adding an alkaline formiate, the noble metals will be immediately and entirely precipi- tated in a very minute state of division. At the same time, by ascertaining the weight of the gas simultaneously evolved, that of the metal thrown down may be deter- mined. 5280. From its solution in water, the bichloride of mer- cury is converted into calomel with so much facility, and in a state of division so perfect, by formic acid or formiate of soda, that their employment in the preparation of that protochloride was suggested by Dobereiner. 5281. If the same quantity of sulphuric acid and man- ganese be mingled with six parts of alcohol, the process being, in other respects, the same as that for formic acid above described, formic ether becomes the predominant product. It is freed from formic acid by magnesia, from alcohol by a small quantity of water, and from water by chloride of calcium. By a more extensive contact with water, formic ether is decomposed, and alcohol and formic acid are generated. 5282. Formic acid has a pungent taste, and a peculiar sharp odour. It is more energetic in its affinities than acetic acid. The formiates, like the acetates, are gene- rally very soluble. OF MODIFIED ACIDS. 473 Of Valerianic Acid, O H O 3 + HO. 5283. This acid was described in the last edition of this Compendium, as a product yielded by the root of valerian, (valeriana officinalis,) when subjected to distillation with water. Since that time, it has been found to be producible, artificially, from a totally different source. It has been dis- covered by Cahours, that if oil of potato spirit (hydrated oxide of amyl, 4023), be allowed to fall in successive drops no faster than it can be im- bibed upon platinum black, previously heated, an acid vapour arises from the oxidation of the elements of the oils, which has all the properties of the valerianic acid, obtained from the root of valerian as above mentioned. 5284. During this process, two atoms of hydrogen are replaced by two atoms of oxygen, so that it is quite analogous to the play of affinities by which the acetic and formic acids are generated ; the former from alcohol, the latter from pyroxylic spirit. 5285. Valerianic acid is also generated in potato spirit, by the sponta- neous absorption of atmospheric oxygen by exposure to the air. 5286. Valerianic acid is a colourless liquid, having an oleaginous con- sistency, a sharp, acid taste, and a persistent odour, which recalls that of the root of valerian. In the state of protohydrate, according to Graham, it produces a white spot upon the tongue when applied to it. The density of this acid is nearly 937 at 62. It boils without alteration at 347, and remains liquid at 5. When heated in a platinum spoon it takes fire rea- dily, burning with a white flame and much smoke, leaving little residue. It is soluble in eighty times its weight of cold water, and in all proportions in alcohol. It is capable of taking up 20 per cent, of water without losing its oily consistence. 5287. From the formula of this acid it is supposed, that it may consist of a compound radical analogous to acetyl, for which the name valeryl is suggested; formula, C 10 H 9 . Of Cafeic Acid and Cafee Tannic Acid. 5288. According to Kane, the coloured precipitate produced in a decoc- tion of raw coffee, by subacetate of lead, comprises two substances, which may be extracted by impregnation with sulphydric acid while suspended in water, subsequent evaporation of the filtered liquid to the consistence of syrup, and digestion in strong alcohol. A peculiar kind of tannic acid dis- solves, called caffee tannic. A white powder subsides, which, when heated, evolves the peculiar smell of roasted coffee. Its solution in water reddens litmus. It is called caffeic acid. It is not known whether the tannic acid of tea and coffee are the same. Of Acids modified by an Union with Organic Matter. 5289. Two sets of acids may claim this description. Of these, in one set the organic matter to which the change in them is due, is an oxidized compound organic radical, acting as a base, capable, under favourable circum- stances, of being transferred to other acids. In the other set, the matter producing the change does not contain a 474 ORGANIC CHEMISTRY. compound radical, capable by oxidation of acting as a base, and transferrable to other acids. Of Acids modified by Union with an Oxidized Compound Radical. 5290. Acids of this set, when formed of a monobasic acid, require for existence two atoms of acid and two atoms of base. One of the acid atoms must be in union with the oxidized radical, the other in union with an atom of basic water, or some other oxide acting as a base. Hence, as already suggested in the case of sulphovinic acid (3086), such compounds may be viewed as double salts of an oxi- dized radical and oxide of hydrogen, so that, agreeably to the language of Graham, sulphovinic acid is a sulphate of ether and water. But this does not explain the fact, that a neutral compound of the acid and oxidized radical cannot be made. Hence, another view, presented by the same author, seems to be more satisfactory, agreeably to which the two atoms of acid act as one bibasic acid,* of course isomeric with that of which it has been formed. This ra- tionale seems to derive strength from the fact, that one atom of tartaric acid in tartrovinic acid, performs the part of two of sulphuric acid in sulphovinic acid, agreeably to the usual idea. 5291. In the other set of modified acids, the organic matter does not appear to be in a basic state, not being an oxide of a compound radical, nor capable of separation without decomposition. 5292. In three of the acids belonging to the first set (sulphovinic, phosphovinic, arseniovinic acid), ethyl, being the principal radical, is united to an inorganic acid. 5293. There are other instances, as in that of sulpho- methylic acid, in which the oxide of a compound radical plays the same part in combination with a double atom of sulphuric acid, that the oxide of ethyl plays in the three acids above mentioned. Also in tartrovinic, oxalovinic, and camphovinic acid, one atom of tartaric, oxalic, or camphoric acid, performs the office of a double atom of sulphuric, arsenic, or phosphoric acid, in the analogous compounds arising from their association with the same oxidized radical. Other acids exist, having a similar con- * Elements, 773. OF SULPHOVINIC ACID. 475 stitution to those last mentioned, and that there will be many more produced hereafter, there is much reason to suppose. 5294. In the second set, there are several which are as- cribed to an union of hyposulphuric acid with carbon, hy- drogen, and water; as, for instance, Isethionic C acid consisting of } + C 4 H 4 O Hyposulpho-naphthalic < S 2 O 5 hyposulphu- - + C 20 H 8 Hyposulpho-benzoic ( ric acid ) + C 14 H 4 O 3 5295. Other acids consist of the elements of some defi- nite organic compound, such as sugar or indigo, so united to an acid as to form, with bases, crystalline compounds; which, besides the peculiarity of their crystalline form, have a solubility altogether wanting in the salts generated, per se, by the acid with which they are formed. This de- scription is intended for sulpho- saccharic acid, and hypo- sulpho-indigotic acid; one created by the union of indigo with hyposulphuric acid, the other by the union of sugar with sulphuric acid. 5296. Analogous to the former of these acids, a new acid has been created, by the reaction between sulphuric acid and acetic acid, of which the formula, represented as C 4 H 4 O 3 -f S 2 O 5 , makes it a compound of hyposul- phurous acid; but Berzelius suggests that the same ulti- mate elements, in a different order, would give C 4 H 4 O 2 + 2$O 3 ;* and that the formula thus made out, being di- vided by two, would give C 2 ITO + SO 3 . This would make it a sulphated oxide of elayl, of olefiant gas in other words (3095).t Of Sulphovinic Acid, or the, Sulphate of Ether, and Water. 5297. Of the acids above described, of the first class, I shall here treat of sulphovinic acid only. While the limits prescribed to a text-book do not allow me to do more, the importance of this acid, arising from the part which it performs in the production of ethers, and the expediency of select- ing it as an exemplification of the set to which it belongs, renders it pro- per that 1 should add something to the notice already taken of it under the head of ethyl (3069). 5298. Sulphovinic acid is produced by heating, to the boiling point of the resulting mixture, or about 280, equal weights of concentrated sulphuric acid and alcohol of from 830 to 850; or by saturating sulphuric acid with the vapour of ether, and adding water after some hours have elapsed. In * Report on Chemistry for 1841. t It also contains the elements of a hydrated bisulphate of the oxide of acetyl. C C8 N 3 H4 10 \ O + 5HO = alloxantine, C" N 3 H* O" 1 1 ammonia + 2HO = uramile C 8 N 3 H 5 O 8 OF URIC ACID. 485 Of Uric Acid, and various Substances to which it gives rise. Of Uric Acid, C 10 H* O 8 N 4 . 5361. As the most frequent and abundant material in urinary calculi, uric acid, and the substances which con- tribute to its formation, or which may be derived from it, merit the most sedulous attention. 5362. This acid is an ingredient in the urine of men, and generally in that of carnivorous animals, forming, as already mentioned, calculi, depositions from urine, and gouty or arthritic concretions. In the state of urate of ammonia, it constitutes the greater proportion of the ex- crement of the boa constrictor and other serpents; also of birds, more especially those of the carnivorous species. I found it to abound in that of a young eagle. An accumu- lation of the excrement of certain aquatic birds, containing a large amount of this acid, on some islands near the coast of Peru and Chili, under the name of guano, is much used as manure. 5363. I infer that the best process for obtaining uric acid is as follows: Boil the substance from which it is to be extracted in a dilute solution of caustic potash. On al- lowing the decoction to cool, urate of potash, which is al- most insoluble in cold water, precipitates, leaving some impurities in solution. After being well washed with water, the urate thus separated is redissolved in a boiling solution of potash, next filtered, while hot, and afterwards added to an excess of chlorohydric acid maintained in a state of ebullition. The uric acid which precipitates, is to be rendered pure and white by repeated aqueous ablu- tion. 5364. Liebig recommends, that in extracting uric acid from excrement, a solution of borax be employed, as it does not take up so large a portion of the impurities as caustic potash. 5365. Uric acid crystallizes in thin spangles, with a daz- zling white satin lustre. It is insipid and inodorous. At a boiling heat the crystals sustain no loss of water. It is heavier than water, almost insoluble in that liquid when cold, and but little soluble in it when hot. The solution feebly reddens litmus. 5366. When to a well refrigerated aqueous solution of 486 ORGANIC CHEMISTRY. borate of soda, holding uric acid dissolved, chlorohydric acid is added, the uric acid precipitates in a hydrated state, forming a transparent jelly, which, by a feeble heat, is converted into a crystalline powder, consisting of anhy- drous uric acid. 5367. This acid is soluble in concentrated sulphuric acid, but separates on dilution with water. It is more soluble in concentrated chlorohydric acid than in pure water. 5368. Subjected to dry distillation, it yields the same products as urea, that is to say, cyanic acid, cyamelide, cyanhydric acid, a little carbonate of ammonia, and a brown and carbonaceous residue very rich in nitrogen. During this decomposition, the hydrated cyanic acid and ammonia unite in the neck of the retort, forming urea. 5369. In dilute nitric acid, uric acid dissolves, with lively effervescence, from the escape of equal volumes of carbonic acid and nitrogen. The resulting solution con- tains alloxan, alloxatin, urea, parabanic acid, and ammo- nia. 5370. By the addition of an excess of ammonia, the concentrated liquid becomes purple red, from the genera- tion of murexide. This effect is one of the means of re- cognising the acid. 5371. Fused with hydrate of potash, uric acid produces, with the alkali or its metal, a carbonate, a cyanate, and a cyanide. 5372. Subjected to boiling water with the bioxide of lead, it is resolved into allantoin, oxalic acid, and urea. Heated to 320, with a little water in a tube hermetically sealed, this acid is dissolved, without the evolution of gas, forming a yellow transparent liquid, which, on lowering the temperature, assumes a gelatinous appearance. 5373. Uric acid is peculiar in combining with metallic oxides, without abandoning water. The urates of the al- kalies and alkaline earths are little soluble in cold water, but very soluble in this liquid when boiling, the solubility being augmented by an excess of alkali. The urates formed with other metallic oxides and with ammonia, are white and insoluble. All the urates are easily decompo- sable by acids, even by the acetic acid. When first libe- rated, uric acid assumes the form of a jelly, which is soon changed into fine brilliant spangles. OF URIC ACID. 487 5374. Allantoin is a substance arising from the urine of a fetus in the ttterus of a cow, and may be obtained from the waters of the allantois of this animal, by evaporation and crystallization. Jt may be more easily procured by the following means: To uric acid, diffused through twenty parts of boiling water, freshly prepared, bioxide of lead is to be added as long as the colour is affected. The boiling liquor is to be filtered, and eva- porated until crystallization commences. It is then allowed to cool in a quiescent state. By this procedure the allantoin separates in crystals, an oxalate of the protoxide of lead being simultaneously produced. 5375. In order to understand this process, the composition of the mate- rials and products should be remembered. They are as follows: Uric acid, C 10 H 4 N 4 O 8 ; bioxide of lead, one atom of protoxide, one of oxygen; urea, C 2 N 3 H* O 3 ; allantoin, C 4 N 4 H 5 O 5 ; oxalic acid, C 3 O 3 . 5376. Hence, assuming that five atoms of water are taken up, and one atom of oxygen for, each of the four atoms of bioxide of lead, the materials are: Two atoms of uric acid, - - - C 30 H 8 N 8 O ia Five water, - H 5 O 5 Four oxygen, - O * C 20 H 13 N 8 O 31 The products are two urea, C * H 8 N 4 O * Four oxalic acid in the oxalate, C 8 O 13 One allantoin, - - - - C 8 H 5 N 4 O 5 C 20 H 13 N 8 O 21 The protoxide of lead being in both of the aggregates, does not affect the result by being omitted from both. 5377. It is from the results of this reaction between uric acid and bioxide of lead, that Liebig has inferred the existence of uril as above mentioned (5319). 5378. Alloxan, or erythric acid, is one of the products which have re- sulted from the decomposition of uric acid. To prepare alloxan, one part of uric acid is to be added to four of nitric acid, of a density between 1.41 and 1.5. As the reaction causes much heat and effervescence, the uric acid should be added in successive small portions. Little white granular bril- liant crystals are gradually formed, until the whole becomes one aggregate of them, which, after being allowed to drain in a glass funnel, must be dried on porous brick, of porcelain earth. By re-solution and re-crystallization, the crystals of alloxan, thus formed, will be rendered quite pure. 5379. Alloxan crystallizes in octahedra, with rhomboidal bases, colour- less, transparent, very brilliant, and often of an inch in diameter. They are efflorescent, losing 25 per cent, of water. By a gentle heat, alloxan, thus crystallized, is rendered anhydrous. It may be obtained in anhydrous crystals, in the form of oblique rhomboidal prisms, which resemble rhom- boidal octahedra with truncated summits, from an aqueous solution of al- loxane saturated while hot. It is very soluble in water, has a nauseous smell, and a salt and feebly astringent taste. It reddens vegetable colours, and tinges the skin purple. By reaction with alkalies, it is decomposed into alloxanic acid. Boiled with an alkali, it is transformed into urea and mes- 488 ORGANIC CHEMISTRY. oxalic acid. It is transformed into alloxantin by sulphuretted hydrogen, chloride of tin, or metallic zinc, and chlorohydric acid. An excess of am- monia transforms it into mycomelic acid. Nitric acid converts it into para- banic acid; sulphuric or chlorohydric acid into alloxantin; sulphurous acid and ammonia into thionurate of ammonia ; alloxantin and ammonia into murexide. Subjected, simultaneously, to an alkali and a salt of protoxide of iron, it produces an indigo-blue liquid. With metallic oxides it cannot combine without decomposition. 5380.* Alloxanic acid (supposed anhydrous), C 4 N 3 HO 4 ; is produced 'by the metamorphosis of alloxan by caustic alkalies. The anhydrous acid contains the elements of half an atom of alloxan, minus one atom of water. 5381. Mesoxalic acid (hydrated), C 6 O 9 H + 4HO; or rather C 3 O 4 + 2HO, is one of the products of a solution of alloxanate of baryta or stron- tian, saturated at a boiling heat. Also, when a solution of alloxan is poured, drop by drop, into a boiling solution of acetate of lead, a very heavy granu- lar mesoxalate of lead precipitates, while nothing remains in the acid liquor besides the excess of acetate of lead and pure urea. Both this and the pre- ceding acid may be separated and crystallized. They are powerful acids. 5382. Mycomelinic acid, C 16 N 8 H 10 O 10 , is formed on adding an excess of ammonia to a solution of alloxan, and raising the mixture to the boiling point. It is almost insoluble in cold water, and is thrown down as a yel- low gelatinous precipitate, which becomes a yellow porous powder on dry- ing. 5383. Parabanic acid, C 6 N a O 4 -f 2HO, is one of the products of the decomposition of uric acid or alloxan by nitric acid, discovered by Liebig and Woehler. It is prepared by dissolving one part either of uric acid or alloxan in eight parts of nitric acid of ordinary strength, evaporating the liquor to a syrup, and allowing it to crystallize. 5384. It has a very sour taste, resembling that of oxalic acid, and forms thin transparent six-sided prismatic crystals. It is very soluble in water and does not effloresce; it is in some degree volatile. 5385. Oxaluric acid, C 6 N 2 IP O 7 + HO, is formed on adding ammonia to a boiling solution of parabanic acid, or on supersaturating with ammonia a solution, recently prepared, of uric acid in nitric acid, which yields, by evaporation, crystals of oxalurate of ammonia. The acid, when separated, is a light brilliant white crystalline powder; its taste is very sour, and it reddens litmus. Its aqueous solution is decomposed completely by ebulli- tion, and resolved into oxalic acid and oxalate of urea. It is formed by the combination of the elements of parabanic acid with two atoms of water. The crystallized acid contains the elements of two atoms of oxalic acid and of one atom of urea, and may be considered as uric acid in which the urile is replaced by oxalic acid. 5386. Thionuric acid, C 8 N 3 H 5 O 6 (S 3 O 6 ) + HO, is a bibasic acid produced by the simultaneous action of sulphurous acid and ammonia upon alloxan. Liberated from thionurate of lead by sulphuretted hydrogen, it crystallizes in very thin needles, is persistent in air, very soluble in water, and has an acid taste. It contains the elements of one atom of alloxan, one * Finding Graham's Elements to contain an abridgment of the account given by Liebig, of the compounds, or products, of uric acid, I have made a free use of it, with such changes in the language as to make it my own, where it was not such as I should have used. In some cases I have made a similar use of Kane's Elements, and of Gregory's Translations from Liebig, especially in the account of saliculous acid and its compounds. OF URIC ACID. 489 atom of ammonia, and two atoms of sulphurous acid. On heating thionuric acid, two atoms of oxygen of the alloxan reunite with two atoms of sul- phurous acid to form sulphuric acid, while the elements of urile, ammonia, and water, combine and give rise to uramile. 5387. Uramile, C 8 N 3 H 5 O 8 , is prepared by adding hydrochloric acid to a saturated and boiling solution of thionurate of ammonia, till it is strongly acid. The heat is continued till the liquid begins to become turbid; it is then allowed to cool for crystallization. Uramile crystallizes in thin and hard tufts; or presents itself in the form of a brilliant white powder com- posed of very thin silky needles. It is sparingly soluble in hot water, wholly insoluble in cold water, dissolves in ammonia and caustic alkalies, and is again precipitated, without alteration, by acids. Either diluted acids or a solution of potash, boiled upon uramile, convert it into uramilic acid, disengaging ammonia. The arnmoniacal solution of uramile becomes pur- ple-red in air, and deposits crystalline needles of a green colour and metal- lic lustre. In contact with oxide of mercury or oxide of silver, it is decom- posed, by ebullition, into murexide, and at the same time reduces the oxides to the metallic state. 5388. Uramilic acid, C 16 N 5 H 10 O 15 , is prepared by dissolving thionu- rate of ammonia in cold water, adding to the saturated solution a small quantity of sulphuric acid, and evaporating by a water-bath. After a time, uramilic acid is deposited in transparent four-sided prisms of a vitreous lus- tre, or in silky needles. It is soluble in six or eight parts of cold water, and in three parts of boiling water, forming a feebly acid solution. For the creation of uramilic acid, two atoms of uramile unite with the elements of three atoms of water, yielding up, at the same time, the elements of one atom of ammonia. 5389. Alloxantin. Formula, C 8 N a H 5 O 10 . Alloxantin was first ob- served by Dr. Prout among the products of the decomposition of uric acid by nitric acid, and more lately produced and studied by MM. Liebig and Woehler, by whom several processes are given for its preparation. 1. From uric acid. One part of uric acid is boiled with thirty-two parts of water, and dilute nitric acid added, by small portions at a time, till the uric acid is completely dissolved, and the liquor evaporated to two-thirds. In the course of a few days, or sometimes a few hours, the alloxantin is deposited in crys- tals, which are purified by new crystallizations. 2. From alloxan. It is produced in large quantity by conveying a stream of sulphuretted hydrogen into a solution of alloxan. Sulphur is first deposited, and then the whole becomes a thick mass of crystals of alloxantin, which are separated from sulphur by solution in boiling water. The alloxantin crystallizes by evapo- ration in a state of purity. 3. On exposing a solution of alloxan to the ac- tion of the voltaic battery, oxygen is evolved at the anode, and alloxantin is deposited at the cathode in crystalline crusts. 5390. Alloxantin crystallizes in oblique prisms of four sides, which are colourless or slightly yellow, hard, and easily reduced to powder; they be- come red in air impregnated with ammonia, and acquire a green metallic lustre. They are not altered at 212, but at 302 (150 centig.) lose three atoms of water; are sparingly soluble in cold water, more soluble in boiling water; the solution reddens litmus. Alloxantin heated in chlorine-water, or in strong nitric acid, is changed into alloxan. With salts of silver it pro- duces a black precipitate of metallic silver. It is decomposed by alkalies; baryta-water produces, in its solution, a violet precipitate, which is made colourless by heat, and finally disappears. By the action of boiling sui- 490 ORGANIC CHEMISTRY. phuric acid, two atoms of alloxan are converted, with the concurrence of two atoms of water, into one atom of alloxantin, three atoms of oxalic acid, two atoms of ammonia, and two atoms of carbonic acid. 5391. The circumstances of the formation of alloxantin are thus ex- plained by M. Liebig. By the action of nitric acid, the uril of the uric acid combines with one atom of oxygen, and with the elements of five atoms of water, giving rise to one atom of alloxantin, and to quadroxide of nitro- gen, NO*, which, in contact with water, is converted into nitrous and nitric acids; the nitrous acid is decomposed, and half of the urea set at liberty; while the other half of the urea forms, with nitric acid, nitrate of urea. In the process with sulphuretted hydrogen, one atom of oxygen of the alloxan combines with hydrogen from the sulphuretted hydrogen to form water, which remains in the constitution of the alloxantin ; the sulphur set free is deposited. 5392. Products of the decomposition of Alloxantin. When a stream of sulphuretted hydrogen is carried into a boiling solution of alloxantin, more sulphur is deposited, and on saturating the solution with ammonia, a salt crystallizes in thin colourless needles, of which the formula is C 8 N 3 H 7 O 3 , which is considered a compound of a new acid, dialuric acid, with ammonia. This acid is resolved into new products when liberated by ano- ther acid; one of these produced by exposure to air, and evaporation of the solution of the ammoniacal salt in dilute sulphuric or hydrochloric acid, is dimorphous alloxantin, a body having the same composition as alloxantin with a different form. On mingling boiling solutions of sal ammoniac and alloxantin, the mixture becomes suddenly of a purple-red colour, then gra- dually loses its colour, becoming turbid, and deposits colourless brilliant plates of uramile, which become rose-red on drying. The liquid contains, after its decomposition, alloxan and free hydrochloric acid. When a solu- tion of alloxantin is heated with caustic ammonia, uramile and mycomeli- nate of ammonia are first formed, but are decomposed into other products by the prolonged action of ammonia and air. A recent solution of alloxan- tin in ammonia gradually absorbs oxygen from the air, and deposits crys- tals of oxalurate of ammonia. Murexide. 5393. Formula, C 12 N 5 H 6 O 8 (Liebig and Wcehler). This beautiful product of the decomposition of uric acid was first described by Dr. Prout, under the name of purpurate of ammonia. Murexide may be formed by evaporating a solution of uric acid in dilute nitric acid, until it acquires a flesh-red colour, and treating it, when cooled to 160, with a dilute solution of ammonia, till the presence of free ammonia is perceptible; the liquid is then diluted with half its volume of water, and allowed to cool. It may also be formed by the contact of ammonia with various other products of the reaction of nitric acid with uric acid, with ammonia, with or without the presence of atmospheric air. 5394. The following method, proposed by Liebig and slightly modified by Gregory, appears to be the easiest and most certain, and also most pro- ductive: Seven grains of hydrated alloxan, and four grains of alloxantin, are dissolved by boiling in 240 grains of water, and the boiling solution added to 80 grains, by measure, of a cold and strong solution of carbonate of ammonia. This mixture has precisely the proper temperature, and de- posits very fine crystals of murexide. The experiment is not so successful OF URIC ACID. 491 on a large scale; probably because the liquid, by remaining longer warm, undergoes a partial change. It is best to try first a saturated solution of carbonate of ammonia in cold water. If it do not yield good crystals, add a little water, and repeat the experiment till a solution of the carbonate is obtained, which gives a good result. The difficulty is owing to the sponta- neous formation of different carbonates by the action of water on the car- bonate of the shops; but when a proper solution is obtained, the experiment never fails. 5395. Murexide crystallizes in short four-sided prisms, of which two faces, like the upper wings of cantharides, reflect a green metallic lustre. The crystals are garnet-red by transmitted light. Their powder is reddish- brown, and acquires a green lustre under the burnisher. Murexide is but slightly soluble in cold water, but colours it of a magnificent purple; it dis- solves, however, readily in water at 158, and crystallizes again as the so- lution cools. It is insoluble in alcohol, ether, or in water saturated with carbonate of ammonia. But this substance cannot be purified or obtained in crystals of large size by crystallizing it from boiling water; for on boil- ing murexide in a small quantity of water for the time necessary to dissolve the whole, the crystals become colourless, and, upon cooling, a yellow gela- tinous matter precipitates. Hence, probably, the slight uncertainty which attends even the best process for the preparation of this substance. Murex- ide dissolves in a solution of potash, producing a superb indigo-blue colour, which disappears with the application of heat, ammonia being disengaged. All the inorganic acids decompose murexide, precipitating from its solution murexan in small brilliant plates. Sulphuretted hydrogen decomposes it immediately into alloxantin, dialuric acid and murexan, while sulphur is set free. 5396. Murexan, C 6 N 3 H 4 O 3 , was named purpuric acid by Prout. It is formed on dissolving murexide with heat in caustic potash, heating till the blue colour disappears, and then adding an excess of dilute sulphuric acid. It crystallizes in colourless plates which have a silky lustre, and are very brilliant; is insoluble in water and dilute acids; it dissolves in ammo- nia and other alkalies, in the cold, without neutralizing them. The proper- ties of murexan closely resemble those of uramile. Like uramile, murexan boiled with water, red oxide of mercury, and a little ammonia, yields mur- exide. The composition of murexan and uramile, also, not differing much in 100 parts, Dr. Gregory admits it to be possible that these two substances may be essentially the same. 5397. As the habitudes of uric acid, and of the substances from which it may be generated, or to which it may give rise, must be an object of inte- rest to the surgeon and physician, I have deemed it proper to make a co- pious abstract respecting it from Graham. I do not, however, as respects other bodies, deem it expedient to go farther into these boundless regions of chemistry. The multiplication of compounds, rendered distinguishable in their properties by shifting the associations of ponderable, with imponderable matter, seems to be as unlimited as the images which may be produced in the kaleidoscope, by varying the relative positions of the coloured beads: and as, in a majority of instances, the compounds created by the changes alluded to, have either the electro-positive, or electro-negative character, which distinguishes acids and bases from other bodies; so it must happen that there will be a prodigious and increasing number of substances stamped with the attributes of acidity or basidity. Even adepts in the science will 63 492 ORGANIC CHEMISTRY. find it impossible to retain any available knowledge of the details respecting such compounds, and of course, however important it may be to register all that is known of them in systematic works, in a text book it can answer no good purpose to dwell on that which could not be remembered even if it were once well learned. 5398. I propose, however, in an appendix, to give some alphabetical ta- bles, in which the information, with which it were inexpedient to clog the body of this work, may be found. On the Influence of Benzole Acid in lessening the Generation of Uric Acid in Human Urine. 5399. Allusion has been made to the discovery, by Mr. Alexander Ure, that benzoic acid, taken into the human stomach, is converted into hippuric acid, causing a diminu- tion of the uric acid generated in the urine. The observa- tions and inferences of Ure have been confirmed by those of Bouchardat, who alleges, that in the case of a patient in the hospital of Hotel Dieu, at Paris, labouring under acute rheumatism, and whose urine was depositing an abundance of uric acid, the spontaneous deposition of the acid ceased after the due administration of benzoic acid : also, it is al- leged by Mr. Garrod, that having repeatedly performed tire's experiment, by swallowing from a scruple to half a drachm of benzoic acid at a time, he had always been ena- bled to obtain from his urine, passed three or four hours subsequently, on the addition of hydrochloric acid, from fifteen to twenty-nine grains of hippuric acid.* 5400. There is, however, the opposite testimony of a commission of the French Academy of Sciences, drawn up by Gay Lussac and Pelouze, that they could not find any verification of the results of Mr. Ure. Agreeably to the knowledge which I have obtained respecting the manner in which such commissions are managed by some of the most distinguished of the academicians, I attach very little importance to their negative testimony. With excellent intentions, they are too much occupied, too much dis- tracted, to do their duty well in such cases. 5401. I have not met with any statement tending to ex- plain in what manner the elements of benzoic and uric acid can give rise to hippuric acid. * Bell's Pharmaceutical Journal, London, page 50. No. 12. June, 1842. OF ORGANIC ALKALIES. 493 OF ORGANIC ALKALIES OR BASES, Also called Vegetable Alkalies, Vegeto-Alkalies, or Alkaloids. 5402. The discovery of the substances which bear the above mentioned names, is of the highest importance to mankind. It has enabled the physician to avail himself of the active principles of some of the most powerful reme- dies, with a certainty which was before unattainable. The patient, in lieu of being nauseated and even injured by doses, of which the greater part, perhaps the whole, may be inert, if not injurious, has to swallow nothing which can be inefficacious, when judiciously prescribed. 5403. The organic alkalies are entitled to rank as bases, under the definition of acidity, deduced from the practice of chemists, and given in this work (note 631), that what- ever saturates a well defined acid must be deemed a base. 5404. The compounds formed with acids by the alkaline bases, under consideration, resemble those formed with metallic oxybases; their acids and ingredients being no less susceptible of precipitation by the appropriate tests. Thus their sulphates are liable to be deprived of their acids by a solution of baryta, their chlorides by solutions of silver or lead. There is in this respect a striking difference between the habitudes of these organic alkaline bases and those which are formed of oxidized compound radicals, like the oxides of ethyl, formyl, and methyl, which cannot be trans- ferred from one acid to another, unless in a nascent state, or under peculiar circumstances. Even when isolated, the bases last mentioned refuse to unite with hydrated acids, which is far from being the case with the alkaline bases in question. Generally, the latter differ very much from the alkalies proper, in being much more soluble in alcohol than in water. In consequence of this last mentioned trait their alkaline reaction with vegetable colours is very feeble, be- ing displayed more in their power of restoring such colours, than by directly producing the changes which result from solutions of the inorganic alkaline bases. 5405. The following table of the organic alkalies indi- cates their sources and composition: 494 ORGANIC CHEMISTRY. Pf|6bbpcp H p6|p^| MW>c^-- O zJ Q , PH Q o pq Vf r-* T ^*T 'W rm. X . s g^jd S^^3 > S 5.S ^ o t: 3 j> QJ i^pQ PQ U "^ ^ U $ ine, amorphin( udomor o i -| OH ^ O fc, 0.0 iat or mor orphia or orphia codei Cti U fl ^ VH c O ^ H Ctf rph ra P O G a-i-l! o r e od a .ar .s'3 ' - ^ ri QQ O ra ro .- SPHP^^^^U OF ORGANIC ALKALIES, 495 I! . o S. 'Mlsr* .1*0 cd J i LI c ^ o> c 'S ^3 ^j Iff a o .s ;-=H a? .S i .a a es g-.S =- IIJS I | tl ill ff! i.*. as sa-s :-. * - .-_; - O "3 .^ - 5 X 3 "o ^^ S llSiSi'lssIs 'llllsii^fi - '- sl s 496 ORGANIC CHEMISTRY. 5406. The salts, formed by the organic alkalies with oxacids, always contain the elements of an atom of water essential to their existence. In this respect they agree in their habitudes with the analogous ammoniacal compounds formed with the same acids. But in uniting with chlorohydric acid, or other halohydric acids,* no water is requisite. In this respect also, there is an agreement between their habitudes and those of ammonia. Hence it might be reasonably inferred that in the one case the halogen body unites with a hydruret of the organic alkali, while in the other, the oxacid unites with an oxide of such a hydruret. This theory has made no change in the names of ammoniacal oxysalts ; but as respects haloid compounds it has changed muriate of ammonia into chloride of ammonium, and induced an analogous result in the case of the ammoniacal compounds of each halogen body. Consistency then would seem to require that a like change should be made in the nomenclature of the compounds of the halohydric acids with the organic alkalies ; but we have had no proof that any of those al- kalies are metallized, and of course could not call muriate of morphia chlo- ride of morphium. Under these circumstances, chlorohydruret is the name to which I would resort for any compound of chlorohydric acid with an or- ganic base. In practice, however, until the relation between ammonia and these alkalies is better understood, it will be as well to employ the officinal appellation (muriate) above mentioned ; keeping the other in view in order to prevent a theoretic misconception, that any combination can be formed with an organic base which merits to be designated as a muriate. 5407. The organic alkalies are, for the most part, pro- ducts of vegetation; yet the following substances, not de- rived from vegetables, are alleged to be allied to the class of vegetable bases, ammeline, melamine, aniline, urea: also some substances obtained from the animal oil of Dippel, called severally odorine, ammoline* and animine. Organic Alkalies of doubtful Existence. 5408. " The following bases are still problematical : api- rine, azaridine, blanchinine, buxine, carapine, castine, chi- occine, crotonine, cynapine, daphnine, digitaline, esenbeck- ine, eupatorine, euphorbine, fumarine, glancine, glaucopic- rine, jamaicine, menispermine, paramenispermine, pitayine, sanguinarine, staphisaine, surinamine, violine. Besides two bases in Carthagena quinquina bark and in chinova bark." Graham's Translation from Liebig, 983. Of the State in which the Organic Alkalies exist in the Pro- ducts of Vegetation, and the Means of extricating them, generally described. 5409. The organic alkalies appear in almost every in- stance to exist in the vegetables to which they belong, in * Halohydric is the generic name which I apply to acids formed of a halogen body and hydrogen. OF ORGANIC ALKALIES. 497 union with an acid. Thus, morphia is united with sulphu- ric and meconic acid, cinchonia and quinia with kinic acid, delphia with malic acid, and veratria with gallic acid. In some instances, the acids have not been specified; but the method requisite for the analysis, shows that they are pre- sent. The salt thus formed is entangled sometimes with resinous matter, sometimes with colouring matter, at others with fatty matter, and in a few instances with caoutchouc. In some cases several, in others all of these impurities may be present. 5410. In the extrication of the organic alkalies charac- terized, and situated as has been stated, the first object of the chemist will be to employ some solvent which will take up the native salt in which it exists. This may in many cases be effected by water alone; but an aqueous solution of some powerful acid, usually sulphuric or chlorohydric acid, appears to have been found preferable. The next step is decomposition of the salt formed with the organic base. This may, of course, be effected by any stronger base, and accordingly, potash, soda, ammonia, lime, and magnesia, have all been more or less employed. The al- kali when insoluble in water, as happens in a great majority of cases, precipitates with or without the precipitant, ac- cordingly as the compound which this forms with the acid is or is not soluble. In either case, the next object to be attained is to extricate the organic alkali from the impuri- ties which may have been precipitated with it. These may consist of resinous matter, fatty matter, colouring matter, caoutchouc, &c. To remove these, washing with weak alcohol, ether and water, has been employed, or re-solution in an acid, and subjection to the depurating and decolori- zing efficacy of animal charcoal. Repeated solution and recrystallization by means of alcohol, or acids, are also used to effect a final depuration. When the alkali to be extricated is soluble in water, and volatile as in the in- stance of conicine, the leaves, flowers, roots or seed, are subjected, with a weak, aqueous, alkaline solution, to the distillatory process. The water which distils in conse- quence, contains more or less of the organic alkali, as well as some ammonia resulting from its decomposition. Being first neutralized by diluted sulphuric acid, then concentra- ted by evaporation, and afterwards digested in a close ves- sel with ether, this liquid dissolves the organic alkali, 498 ORGANIC CHEMISTRY. which may of course be easily isolated by subsequent ex- posure to a water bath sufficiently heated to expel the ether and ammonia. 541 1. In some instances the decomposition of the native salts in which the organic alkalies are constituents, may be effected by acetate of lead. As this metal generally forms insoluble compounds with vegetable acids, by com- plex affinity the acid goes to the oxide of that metal, while the alkali combines with acetic acid. From the solution of the acetate thus formed, the lead of any excess of the acetate of lead may be precipitated by sulphydric acid.* Of Morphia or Morphine. 5412. Morphia, the most important among the active principles of opium, was discovered by Serturner, of Eim- bech, in Hanover, and recognised by him as an organic alkali. This formed the first step in a new career in chemical discovery, having induced those subsequent re- searches by other chemists, to which we are indebted for our knowledge of the series of analogous principles men- tioned in the preceding table. 5413. Morphia exists in opium in chemical union with meconic acid only, but is mechanically associated with various substances, of which an account has been given. (5172.) 5414. It is remarkable, that since we have learned the existence of morphia, it has become evident that the means of detecting its presence in laudanum, almost extempora- neously, had long been at hand in the shop of every drug- gist. Dr. Staples, a graduate of our school, demonstrated, about twenty years ago, that to cause a precipitation of crystals of morphia, it were only requisite to add to that tincture equal parts of liquid ammonia and alcohol. The crystals thus obtained, being redissolved by acetic acid, * The following process for elaborating the organic alkalies, suggested by M. O. Henry, is founded on the property of tannic acid to precipitate the organic alkalies in general. Neutralize by potassa a clear infusion obtained by digesting the vegetable matter containing the alkali, or an extract procured from it, in tepid water, acidulated by sulphuric acid : add an infusion of galls so long as any precipitate ensues. The pre- cipitate, after being washed with cold water, is to be thoroughly mingled with hy- drate of lirne, somewhat in excess, and being dried by the heat of boiling water, must be digested in alcohol or ether. The resulting solution, after filtration, is to be subjected to a heat sufficient to drive off the alcohol. The residual liquid, consisting of water which had been in combination with the alcohol, holds the alkali in solu- tion, and after a few days repose deposits it in crystals. OF MORPHIA OR MORPHINE. 499 and again precipitated by ammonia, may be purified of the matter by which they are, in the first instance, discoloured. A particular account of an improved process, devised by Dr. Staples, may be found in the United States Dispensa- tory, by the editors of which it is highly recommended. 5415. The following process, suggested by Wittstoch, is recommended as probably the best, by Kane. 5416. One part of opium, from eight to ten of water, with two of chlorohydric acid, are to be digested together for six hours. The solution being then decanted, the resi- due is to be subjected twice successively to the same or- deal. The resulting solutions being united, the whole is to be saturated with chloride of sodium. The matter which consequently subsides, is to be separated by filtra- tion, and ammonia being added, in slight excess, to the fil- tered liquid, it must be allowed to rest undisturbed for twenty-four hours. The resulting precipitate is to be col- lected upon a filter, washed with a little water, dried, and digested in alcohol, of 0.820, which takes up the morphia. The greater part of the spirit being removed by distilla- tion, morphia crystallizes on cooling in a state sufficiently pure. 5417. The effect of the chloride of sodium is to preci- pitate narcotina, and some other impurities. The meco- nin, codeia, thebaine, and some other principles, are re- tained in solution by the alcoholic mother liquor. 5418. Morphia crystallizes in rhombic prisms, contain- ing for each atom, two of water, which are liable to be lost by efflorescence. It has an enduring bitter taste, and is almost insoluble in water, as it requires for solution 400 parts, even at the temperature of ebullition, and precipi- tates, almost entirely, as the liquid cools. It has an alka- line reaction, readily dissolves in alcohol, but sparingly in ether. It is also soluble in aqueous solutions of the al- kalies and earths. 5419. As usually procured, this alkali, or any of its combinations, is reddened when brought into contact with nitric acid. The phenomenon is produced by the same acid on contact with other vegeto-alkalies, and, according to Kane, is not produced with morphia when absolutely pure. Subjected to chlorine in water, morphia is first made orange red, and then dissolved. On contact with morphia, the iodine of iodic acid is liberated. A solution 64 500 ORGANIC CHEMISTRY. of sesquichloride of iron assumes a rich blue colour on the addition of morphia, or any of its salts. With tannic acid morphia affords a copious white precipitate. It is capable of neutralizing the strongest acids, and of forming with them compounds which are soluble and crystallizable. 5420. Agreeably to the late observations of Larocque and Thibierge, the perchloride of gold produces with mor- phia a precipitate which is at first yellow, next bluish, and lastly violet. In the state in which it assumes the colour last mentioned, the gold is revived; while the precipitate, of which it forms a part, becomes insoluble in water, alco- hol, caustic alkalies, or in sulphuric, nitric, or chlorohydric acids. Yet with aqua regia, it makes a solution which is precipitated by the green sulphate of iron. 5421. With the oxacids, with organic acids, and with the halogen bodies, morphia generates salts which are ca- pable of crystallization and of being dissolved by water. The medicinal properties of the alkali are not impaired by these combinations. In this country the sulphate is the most used ; but Dr. Kane alleges the " muriate " to be the most important compound of morphia. Of Paramorphia^ or Thebaine. 5422. Paramorphia is an alkali lately discovered by Pel- letier in minute proportion in opium. It is identical with morphia in composition, but quite distinct in its properties. It is, therefore, isomeric with morphia, and hence its name. 5423. Paramorphia is white, scarcely soluble in water, of an acrid and styptic, rather than a bitter taste, and very soluble in alcohol or ether, even when cold, and still more so when hot. It differs from morphia in not being redden- ed by nitric acid, in not forming crystallizable salts with acids, and in not striking a blue colour with the salts of iron. It also differs from morphia in its action on the system, producing tetanic symptoms in doses of a grain. 5424. Pseudomorphia is a name given to another alkali discovered by the same distinguished chemist in opium, likewise in minute proportion. It resembles morphia in the characteristic properties of becoming red with nitric acid, and of striking a blue colour with the salts of iron, and yet differs from it in not being poisonous. It is not always present in opium, and the circumstances under which it is produced are not known. OF CODEIA, NARCOTINA, NARCEIA AND QUINIA. 501 Of Codeia, or Codeine. 5425. This vegetable alkali was discovered in 1832, by Robiquet. It exists in opium as a meconate. It is in the form of colourless crystals, which are soluble in two parts of boiling water, also soluble in alcohol and ether, but in- soluble in alkaline solutions. Its capacity of saturation is very nearly the same as that of morphia ; but it may be distinguished from that alkali by the different form of its crystals, x by its greater solubility in water, and by its in- solubility in alkaline solutions. It has a decided action on the animal economy, producing first excitation, and af- terwards depression. Of Narcotina, or Narcotine. 5426. In order to obtain narcotina, opium may be com- minuted, and digested with as much ether as will cover it, at a temperature near the boiling point of the ether, for three or four days. The ether being decanted and allow- ed to evaporate, the narcotina will appear in slender pris- matic crystals, soiled by caoutchouc, resin, and colouring matter. Being subjected to boiling alcohol and recrys- tallized by refrigeration therefrom, they are rendered purer, and further purified by repeated solution and recrystalliza- tion. To remove all the narcotina, opium must be sub- jected to successive portions of ether. Of Narceia, or Narceine. 5427. This alkali was discovered in opium by Pelletier in 1832. It exists in white, silky, acicular crystals, ino- dorous, of a slightly bitter taste, sparingly soluble in water, more soluble in alcohol, and insoluble in ether. It is ren- dered blue by the dilute mineral acids, but does not, like morphia, become blue with the salts of iron, nor red with nitric acid. Of Quinia, or Quinine. 5428. In the various kinds of cinchonia, known in com- merce as Peruvian bark, there are three organic alkalies, quinia, cinchonia, and aricina, of which the most impor- tant is that which bears the name at the head of this pa- ragraph. Quinia is generally procured from yellow bark. The process usually employed for its elaboration is as follows. The bark, coarsely powdered, is boiled with sul- 502 ORGANIC CHEMISTRY. phuric or chlorohydric acid. In the case of sulphuric acid, the proportions given are three fluid drachms to a gallon of water; in the other case, two of acid to ten of water; a pound of bark being employed. 5429. The bark is to be subsequently exposed to a simi- lar ordeal with a half, and with a fourth part of the quan- tity of acid at first employed. To the united solutions, strained and cooled, add hydrate of lime till there be an alkaline reaction. The precipitate is to be collected. This, when sulphuric acid is used, will consist in part of sulphate of lime; but when the other solvent is used, the lime will remain in solution in the state of chloride. In either state, the precipitate being digested in alcohol, the alkali is taken up. The solution thus formed, is subjected to distillation with water. The residue being treated with sulphuric acid in excess, on evaporation affords crystals of sulphate of quinia; the sulphate of cinchonia remaining in solution. From the sulphate, pure quinia may be ob- tained by adding to a solution of it caustic potash, also in solution, drying the resulting precipitate, dissolving it in a quantity of alcohol, as small as possible, and allowing the liquid thus obtained to evaporate leisurely in a place moderately warm. Under these circumstances, quinia crystallizes in union with an atom of water, forming of course a crystalline hydrate. This water it loses by fusion. Quinia is intensely bitter. It requires for solu- tion, two hundred parts of hot water, and is almost insolu- ble in cold water. In alcohol or ether it dissolves readily. The salts of this alkali are soluble in water, as well as in alcohol, and are capable of crystallizing. In common with those of other alkalies, and of ammonia, the oxysalts which it forms, require an atom of water, as already mentioned (5406). 5430. Of the Chlorohydruret or Muriate of Quinia. This salt forms pearly crystalline needles, which are very solu- ble in water. It acts as a base with chloroplatinic, or chlorohydrargyric acid (corrosive sublimate), forming what are called double salts by some chemists, but which I con- ceive should be called, severally, chloroplatinate or chloro- hydrargyrate of the chlorohydruret of quinia ; or for the sake of brevity, as in other cases, simply a chloroplatinate of morphia, or chlorohydrargyrate of quinia (5406). 5431. Basic Sulphate of Quinia consists of two atoms OF Q.UINIA. 503 of quinine, one of sulphuric acid, and eight of water; its formula being Qu So 3 8HO. The manufacture of this compound is conducted on a large scale, according to the process above given for the extrication of quinine, and va- rious other methods. In crystallizing, this sulphate enters into combination with six atoms of water of crystalliza- tion, and two acting as a base. Hence in dry air, or when gently heated, it relinquishes six, yet retains two, which cannot be expelled without partial decomposition. This salt is but sparingly soluble in water, requiring thirty parts at a boiling heat, and seven hundred and forty in the cold. Of alcohol, unaided by heat, it requires eighty parts for solution; but much less at the temperature of ebullition. Its crystals are small pearly plates or needles, which, when heated, fuse, and phosphoresce vividly, being totally decom- posed at a high temperature. 5432. Neutral Sulphate of Quinia. This salt crystal- lizes in rectangular prisms, of which the formula is Qu So 3 8HO. They are prone to effloresce, dissolve in ten parts of water at 60, and undergo aqueous fusion at 112. This sulphate is very soluble in alcohol, and, though from its constitution it should be neutral, reddens litmus. 5433. Basic Sulphate of Quinia of Commerce. In the state in which basic sulphate of quinia is sold in com- merce, under the name of sulphate, it is sometimes adulte- rated with boric acid and with sulphate of lime. These substances may be detected by exposing the aggregate to a red heat, by which the elements of the sulphate may be dissipated, and the adulterations exposed to view. Sugar and margaric acid have also been used as adulterations. Of these, the latter may be detected by its insolubility in diluted acids, the former by washing a sample in water, and adding carbonate of soda to precipitate the quinia, when the sweet taste of the sugar will become perceptible. 5434. Phosphate of Quinia crystallizes in small, but bril- liant needles, soluble both in water and in alcohol. 5435. Ferroprussiate, or Cyanoferrite, of Quinia is formed by boiling one part sulphate of quinia, and one and a half of cyanoferrite of potassium, in seven of water. The ge- nerated salt separates as greenish yellow, oily substance. The mother liquor being decanted when cold, the cyano- ferrite is to be redissolved in boiling alcohol, whence on refrigeration it crystallizes in greenish yellow needles. 504 ORGANIC CHEMISTRY. On the Reaction of Chlorine with Quinia and its Salts. 5436. If sulphate of quinia be made to form a dilute so- lution with water, impregnated with chlorine, and liquid ammonia be added, a green precipitate ensues, the liquid assuming an intensely green colour. The precipitated substance has been called dalleiochin. If the residual green liquid be evaporated with access of air, it changes to dark red, while sal ammoniac is generated, and two bodies, of which only one is soluble in alcohol. The solu- ble body is called rusiochin, the other, melanochin. Kane's Elements. Of Cinchonia, or Cinchonine. 5437. This alkali abounds in the gray bark (cinchona micrantha) from which it may be extricated by means ana- logous to those employed in the case of quinia. Usually it is obtained from the mother waters of the sulphate of the alkali last mentioned, by saturating the excess of acid by which it is retained in solution during the crystalliza- tion of the sulphate of quinia. Under these circumstances, being precipitated by an alkaline base, and afterwards re- dissolved by alcohol, it is obtained in thin, colourless, pris- matic crystals, by vaporizing this solvent. Its taste is peculiar, as well as bitter. Boiling water only takes up 2rW part; but it readily dissolves in alcohol and ether. It fuses at 330 without loss. Between its salts and those of quinia, there is a great resemblance. 5438. The chlorohydruret of cinchonia crystallizes in bril- liant interwoven needles, and like the congenerous com- pound of quinia (5389) acts as a base with electronegative chlorides, such as chloroplatinic, and chlorohydrargyric acid. 5439. Basic sulphate of cinchonia, C 2 + SO 3 forms rhom- bic prismatic crystals, which require for solution 54 parts of water. The neutral sulphate holding only half as much base, is more soluble, crystallizing in large well formed rhombic octohedrons. Of Aricina, or Aricine. 5440. This alkali was discovered in 1829 by Pelletier and Coriol, in a bark brought from Arica, on the Pacific OF STRYCHNIA AND BRUCIA. 505 coast of South America, which was fraudulently mixed with the Calisaya bark. It is a white, transparent, crys- talline substance, having a warm and intensely bitter taste, which is long in developing itself. It dissolves in alcohol and ether, but is completely insoluble in water. By nitric acid it is coloured green. The salts agree in their proper- ties with those of quinia and cinchonia. Of Strychnia, or Strychnine. 5441. The poisonous principle of the Strychnos nux vomica, and Strychnos ignatia or colubrina, is considered as an alkali, and called strychnia. It may be developed by a process similar to that used for morphia. It was origi- nally obtained by Pelletier and Caventou, by subjecting the bean of the Strychnos ignatia, duly rasped, to nitric ether in a Papin's digester, to remove fatty matter; and subsequent exposure of the residue to alcohol, in which the strychnia, in union with an acid, dissolves. The alco- hol having been evaporated, and the residuum dissolved in water, the addition of potash caused the alkali to precipi- tate. It was afterwards washed in cold water, and redis- solved in alcohol, from which it crystallized by evapora- tion. 5442. The colour of strychnia is white. Its taste is intolerably bitter, leaving a metallic impression in the mouth. It is nearly insoluble in water, or ether, but is very soluble in alcohol. It is a terrible poison, very small quantities producing tetanus to a fatal extent; being used by the natives of Borneo to render their arrows poisonous, under the names either of upas tieuta, or woorara. Of Brucia, or Brucine. 5443. This alkali exists in the bark of the Brucia anti- dysenterica, or false angustura. The bark was first sub- jected to sulphuric ether, and afterwards to alcohol. The alcohol being evaporated, afforded a dry residuum, which was dissolved in water. The solution in water was satu- rated with oxalic acid, and evaporated to dryness. An oxalate of brucia resulted, which, after being depurated by alcohol of colouring matter, with which it was associated and disguised, was decomposed by lime or magnesia. As either of these bases forms an insoluble salt with oxalic 506 ORGANIC CHEMISTRY. acid, while brucia is soluble in 500 times its weight of boiling water, or in 850 parts of cold, it was separated from the insoluble oxalate by water. 5444. Brucia crystallizes in oblique prisms, with paral- lelograms for their bases. It is less bitter than strychnia, but its taste is more acrid and durable. It melts when heated a little above 212, and congeals on cooling into a mass resembling wax. It neutralizes acids, affording a distinct class of salts. On animals, its effects are analo- gous to those of strychnia, but less violent.* Of Delphia, or Delphine. 5445. It was in the seeds of the Delphinium staphisa- gria, or stavesacre, in which it exists as a malate, that this alkali was detected. A decoction of the seeds, which had been cleansed and reduced to a pulp, was filtered. The fluid, which passed the filter, was boiled with magnesia, which liberated the delphia. It was then separated from the magnesia by alcohol, and from this solvent by evapo- ration. 5446. Delphia is white, pulverulent, and very soluble in alcohol and ether. It is inodorous, but its taste is extreme- ly acrid and bitter. Water derives from it an acrid taste, though it does not dissolve any appreciable quantity. By combination with acids, it forms neutral salts, which are soluble in water, and very acrid and bitter. 5447. Concentrated sulphuric acid reddens, and after- wards carbonizes delphia. Chlorine renders it green. Courbe alleges that stavesacre contains, in addition to that which has been described, a yellow, resinous sub- stance, of which the formula is C 32 H 23 O 4 N; and the name suggested for it is staphysain. This is distinguished by insolubility in ether, or water; and solubility in dilute acids, without neutralizing them. * Mr. Fuch advances that brucia is a combination of strychnia with a resin which this last mentioned substance holds obstinately, and which has the pro- perty of being reddened by nitric acid. It is to this impurity that brucia owes its liability to be made red by the acid above mentioned. Mr. Fuch has found a method of separating this resin from brucia, and consequently of converting this supposed peculiar alkali into strychnia. He has not, however, succeeded in causing strychnia to combine with the resin in question so as to form brucia. Although Mr. Fuch mentioned it to be his intention to publish his process for the depuration of brucia, a year has elapsed without any further information having been promulgated by him on this subject. Berzelius' Report for 1841, p. 141. OF VERATRIA AND SABADILLA. 507 Of Veratria, or Veratrine. 5448. Veratria is an alkali obtained from the seed of the Veratrum sabadilla; also from the roots of the Vera- trum album (white hellebore), and Colchicum autumnale (meadow saffron). 5449. The seeds, partially depurated by digestion with ether, yielded a coloured tincture with heated alcohol. This tincture deposited some waxy matter on cooling, and by evaporation afforded a residuum, soluble in water, excepting a small portion of extraneous matter. The wa- tery solution being slowly and partially evaporated, until an orange-coloured precipitate ceased to appear, acetate of lead was added to it. A copious yellow precipitate en- sued, and the liquor, being separated from it by a filter, became almost colourless. This fluid was subjected to sulphydric acid, to precipitate any lead which it might contain. The solution then gave, with magnesia, a precip- itate, from which alcohol took up veratria. From the al- coholic solution, the veratria was afterwards isolated by evaporation. 5450. Veratria is white, pulverulent, and inodorous, but, nevertheless, poisonous when inhaled, producing vio- lent and dangerous sneezing. Its taste is not bitter, but excessively acrid. It reacts like an alkali, is insoluble in water, but very soluble in alcohol and ether. It melts at 230. Its salts are for the most part crystallizable and neutral, but decomposable by water into free acid, and a basic salt. Taken into the stomach in minute quantities, it produces intolerable nausea and vomiting, and in large doses, death. Of Sabadilla. 5451. Sabadilla was discovered by Couerbe, as an al- kali accompanying veratria in veratrum sabadilla, and in the roots of the Veratrum album (white hellebore), and Colchicum autumnale (meadow saffron). 5452. By boiling the precipitate, obtained by carbonate of soda from an infusion of sabadilla seeds in diluted sul- phuric acid, sabadilla may be separated in radiated needles, of a pale rose colour, which may be rendered white by de- puration. This alkali is a white, crystallizable substance, 65 508 ORGANIC CHEMISTRY. in supportably acrid, fusible by heat, readily soluble in hot water, very soluble in alcohol, and wholly insoluble in ether. Of Jervina, or Jervine. 5453. Jervina is found in veratrum album, associated with veratrine, from which the sparing solubility of its sulphate, and its readiness to crystallize from an alcoholic solution with four atoms of water, renders it liable to be separated. Jervina, when pure, is white, easily fusible, de- composable at 400, nearly insoluble in water, but copious- ly soluble in alcohol. Of its salts, the acetate readily dis- solves in water, although in this liquid its sulphate, nitrate, and chloride, are sparingly soluble. The chloride of jer- vina unites with chloroplatinic acid. Kane, 1069. Of Colchicina, or Colchicine. 5454. Colchicina is a vegeto-alkali existing in the seeds of the meadow saffron (Colchicum autumnale). 5455. It may be extricated by the following process. Digest the seeds in a mixture of sulphuric acid and weak alcohol; neutralize the excess of acid by lime, remove the alcohol by distillation, decompose the residual liquor by car- bonate of potash in excess, dissolve the washed and dried precipitate in absolute alcohol, decolorize the solution by animal charcoal, add a few drops of water, and evaporate it until the colchicina crystallizes in colourless needles. 5456. This alkali is intensely bitter, but not so biting to the taste as veratrine, nor is it productive of violent sneez- ing. It is moderately soluble in water, very soluble in al- cohol, or ether. Though but feebly alkaline in its reaction, in other respects it neutralizes acids thoroughly. By tinc- ture of iodine it is precipitated of a rich orange colour, by nitric acid it is coloured dark violet blue. Though most abundant in the seeds, it pervades all parts of colchicum. Kane, 1069. Of Emetia, or Emetine. 5457. This alkali is obtained from ipecacuanha. The roots, well pulverized, are digested in ether. They are then subjected to alcohol, the resulting solution is evapo- rated, and the residuum dissolved in water, and macerated upon magnesia, which causes the emetia to precipitate. OF SOLANIA. 509 This precipitate is washed with cold water to remove co- louring matter, and afterwards subjected to alcohol, which takes up the emetia. The emetine again separated from its solvent by evaporation, being dissolved by diluted acid, and blanched by animal charcoal, may be precipitated pure by any of the alkaline oxides. 5458. Thus obtained, emetia is white, pulverulent, and unalterable by the air, scarcely soluble in water, but very soluble in ether or alcohol. Its taste is slightly bitter. It possesses strong alkaline properties, restoring the colour of litmus, when reddened by an acid. It is capable of forming salts, which, though neutral, are not crystallizable. It appears to possess all the emetic properties of the root from which it is procured. Of Solania, or Solanine. 5459. Solania is the name which has been given to an alkali which exists in the black nightshade (solanum ni- grum), and in the bittersweet (solanum dulcamara), also in the shoots of the solanum tuberosum, or potato. 5460. The filtrated juice of the berries of the nightshade being digested in ammonia, the resulting precipitate is washed on the filter, and digested in boiling alcohol. After the evaporation of this fluid, solania is obtained in suffi- cient purity. It is a white, opake, pearly powder, which is inodorous, slightly bitter, and nauseous. Its acid solu- tions are more bitter. Its salts, though neutral, are un- crystallizable. In cold water it is insoluble, and in hot dissolves only to a small extent. It is very soluble in alco- hol, but is not dissolved by ether. It restores the colour of litmus, reddened by an acid. It causes vomiting at first, afterwards sleep, or death, according to the dose, being a strong narcotic poison. With salts of emetine, tannic acid, or corrosive sublimate, it produces white precipitates; with iodine and chloroplatinic acid, brownish yellow preci- pitates. According to Kane, the injurious properties of unripe potatoes result from the presence of this body. It exists abundantly in the early shoots (underground) and buds of the tubers. 510 ORGANIC CHEMISTRY. Of Caff em or Caffeia* or Theine. 5461. It seems hardly credible that there should be a crystallized nitrogenated principle common both to tea and to coffee. Yet, agreeably to analyses recently made, the substances which had been discovered in tea and coffee, and called theine, or caffein, are identical in composition and properties. 5462. Moreover, a principle elaborated from guarana, a paste made from the seeds of paullinia sorbilis, is alleged by Martius to be identical in composition with caffein, and to be a base in its properties. 5463. To extract caffeia, the raw coffee seeds, well dried and pulverized, are to be exhausted by boiling water. In the next place subacetate of lead must be added to the re- sulting solution. This is to be filtered afterwards, and any excess of lead precipitated by sulphydric acid. After a second filtration, the solution being concentrated suffi- ciently by evaporation, the caffeia crystallizes on cooling. Re-solution, and recrystallization are requisite to render it pure. 5464. Caffeia may also be extricated from a filtered de- coction of tea leaves : hence its other name, theine. 5465. Caffeia assumes the form and appearance of nee- dles, having a silky lustre. It is feebly bitter, sparingly soluble in ether, cold water, or alcohol. At 212 it loses eight per cent, of water. It fuses at 352, and sublimes at 725. From its solution it may be thrown down by tannic acid. Boiled with caustic potash, or baryta, caffeia is re- solved into ammonia, cyanuric, formic, and carbonic acids. With sulphuric or chlorohydric acid it forms crystalline compounds. Its composition, according to Liebig, is re- presented by the formula above given. 5466. Graham alleges that the active properties of tea and coffee are not due to caffeia; but it is admitted that no other vegetable substance contains so large a propor- * Caffeia is one of the crystalline organic principles which it is difficult to name, or to classify, on account of the discordancy of the authorities which bear upon the question. Heretofore it has been placed among the neutral principles, and in the United States Dispensatory, and in the recent works of Kane, Graham, and Grego- ry, has been treated of as such, and called caffeia. But in the report of Berzelius for 1841, it is mentioned that Martius has " found it to be identical with guaranine," an organic base, elaborated from the seeds of paullinia sorbilis. Accordingly it is placed by Berzelius, in his list of contents, under the head of vegetable bases, with morphine, brucia, &e. But while Martius and Berzelius assign to it the rank of an alkali, they do not change the terminating monosyllable, as the continental chemists have not adopted the termination in a for alkaline bases. OF CHELERYTHRINA. 511 tion of nitrogen, and Liebig remarks that 2^ grains of caflfeia may furnish all the nitrogen required by an ounce of human bile. This fact naturally suggests that tea and coffee may be serviceable in furnishing nitrogen for biliary and other secretions, in beings whose habits of life do not make it healthful or agreeable to consume a sufficient quantity of bread and meat to supply all the nitrogen ne- cessary to the vital functions. 5467. According to this view of the subject, it is re- markable, that civilized nations, comprising a majority of mankind, should in modern times have been led, as it would seem, intuitively, to resort to two sources, apparently so different, as the tea leaf and coffee berry, for the same preeminently nitrogenated principle as an almost indispen- sable article of daily food. " Chelerytkrina, or Chelerythrine. 5468. "This substance is extracted from the roots of the chelidonium majus, by digestion with dilute sulphuric acid. The liquor so obtained is to be evaporated and mixed with ammonia. The brown precipitate which falls is to be washed, pressed between folds of paper, and digested in alcohol, with some sulphuric acid. The alcoholic solution being mixed with water, and the spirit distilled off, the re- sidual liquor is precipitated by ammonia, and the precipi- tate being washed and dried by pressure, is to be digested in ether, and the ethereal solution evaporated to dryness. The mass so obtained is then digested in dilute muriatic acid, which leaves a resinous substance undissolved. The deep red liquor evaporated to dryness, and washed with ether, leaves a mixture of muriate of chelerythrine and muriate of cheledonine ; the former of which is dissolved by washing with a small quantity of water, whilst the latter remains undissolved." 5469. "From the solution of the muriate, the cheleryth- rine is precipitated by ammonia, as "a white curdy powder. From its ethereal solution it remains as a resinous mass, which remains soft for a long time ; it is insoluble in wa- ter; its solutions in alcohol and ether are pale yellow. With acids it forms salts of a rich crimson colour, which generally crystallize. Tannic acid produces in their solu- tions a precipitate soluble in alcohol." Verbatim from Kane, 1070. 512 ORGANIC CHEMISTRY. "Chelidonia, or Chelidonine. 5470. " The preparation of this substance has been in great part described in the preceding article. By digest- ing the sparingly soluble muriate with ammonia, then dis- solving in sulphuric acid and precipitating with muriatic acid, it is freed from all traces of chelerythrine, and finally the pure chelidonine, separated by ammonia, is dissolved in boiling alcohol, from which it crystallizes, on cooling, in brilliant colourless tables. It is insoluble in water, so- luble in alcohol and ether; it tastes bitter, and reacts alkaline ; its salts are colourless, and those with the mine- ral acids crystallize ; its solutions give with tannic acid a precipitate." Verbatim from Kane, 1071. Of Atropia, or Atr opine. 5471. Atropia is procured from a decoction of the leaves of the Atropa belladonna, or deadly nightshade. Two pounds of the leaves were boiled in successive por- tions of water, which being united, and sulphuric acid added to the whole, the resulting liquid was filtered, and yielded a crystalline precipitate with potash. This preci- pitate, repeatedly dissolved in acids, and precipitated by alkalies, gave pure atropia. Thus obtained, it is snow- white, and quite tasteless. When recently precipitated, it is slightly soluble in water. After being dried, it is insolu- ble in water, ether, or oil of turpentine. In cold alcohol it is sparingly soluble; but copiously in the same menstruum when boiling hot. 5472. Atropia forms compounds with acids, which can- not, however, be rendered so neutral, as not to indicate acidity. Of Aconitia, or Aconitine. 5473. The fresh expressed juice of the monkhood, aco- nitum napellus, being boiled and filtered, the resulting clear liquor, subjected to an excess of carbonate of potash, is to be agitated with ether so long as it takes up any thing. On vaporizing the ether, aconitia is deposited. From the dry plant, or its seeds, a solution of aconitia may be ob- tained by water holding an ounce of sulphuric acid for each pound. This may be decomposed by carbonate of OF BELLADONIA AND DATURIA. 513 soda, and the alkali extricated from the resulting precipi- tate by ether or alcohol. Aconitia crystallizes from an etherial or alcoholic solution, partly in white grains, but for the most part forms a colourless vitreous-looking mass. It has a sharp bitter taste, and is intensely poisonous. It is capable of neutralizing the most powerful acids. Its so- lutions give a white precipitate with alkalies proper, or with chloride of gold; with iodine an orange precipitate. Of Belladonia, or Belladonine. 5474. This alkali is obtained by subjecting the dried root of belladonna to distillation with a solution of caustic potash, precipitating, from the liquid which comes over, the alkali with which it is accompanied, by chloroplatinic acid, and heating the washed precipitate with carbonate of potash. The belladonia being sublimed, condenses in colourless, rectangular, prismatic crystals. Belladonia, thus isolated, has a penetrating odour resembling that of ammonia, and forms a solution with water, which reacts like that of an alkali. It is not very poisonous. Its salts are much like the corresponding ammoniacal salts. Of Daturia, or Daturine. 5475. The seeds of the datura stramonium, vulgarly known as the thorn apple, Jamestown, or jimson weed, and the juice of the leaves, capsules, and stems, contain the alkaline principle to which the name at the head of this article is given. It is to this, that the efficacy of the ointment constituted by the inspissated juice, and the well known poisonous property of the plant, are due. 5476. Agreeably to the process of Brandes, who first isolated daturia, the seeds are to be boiled in alcohol, and magnesia being added, the resulting precipitate is to be redissolved by the same liquid. According to Kane, it may be obtained by the same processes as aconitia, above described. 5477. From its solution in spirit, it crystallizes in very brilliant groups of needles. It is quite inodorous when pure, although the juice of the plant smells disgustingly narcotic. It is bitter, and tastes somewhat like tobacco. For its solution, it requires 72 parts of boiling water, 250 of cold water, 21 parts of ether, and 3 of alcohol. It fuses below 212, and at a higher temperature volatilizes, un- 514 ORGANIC CHEMISTRY. changed, in white clouds. It reacts like an alkali, and is capable of forming, with acids, crystallizable salts, which are highly poisonous. In its habitudes with reagents, it resembles atropia. Of Conina, or Coneine. 5478. This alkali exists in all parts of the hemlock (co- mum maculatum), especially in the seeds, from which it may be extricated by the following means : They are to be bruised, and being mingled with one part of a concen- trated solution of potash, and eight of water, are to be sub- jected to the distillatory process till the water, which dis- tils, becomes inodorous. The distilled solution, after being neutralized by sulphuric acid, must be evaporated to the consistency of a syrup; and being, in this state, treated two or three times with a mixture of one part of ether, and two of alcohol of 820, the coneine is taken up. Some water being added, the ether and alcohol are removed by distillation, and the residual water by evaporation. The de- siccated residuum is to be mingled with half its weight of a concentrated solution of caustic potash, and subjected to distillation with a receiver carefully refrigerated. The oily portion must be separated from the aqueous portion of the liquid which comes over, and this last again distilled from hydrate of lime. From any ammonia with which it may be associated, the coneine may be freed by exposure for a few hours in vacuo, over sulphuric acid. 5479. Pure coneine is extremely poisonous, existing in the form of a colourless transparent liquid, of the density of .890. Its taste is disgustingly sharp, its smell highly nau- seous and pungent, somewhat like that of the plant. It is soluble in 100 parts of cold water, which becomes turbid by being heated; but four parts of coneine dissolve one of water, forming a solution which may be rendered turbid by the heat of the hand. With alcohol, ether, and oils, it mingles in all proportions. It distils, per se, at 370, but requires less heat when associated with the steam of boil- ing water. It reacts like an alkali with the assistance of water, but not when anhydrous. It is capable of satu- rating acids completely, having the least atomic weight of any known organic alkali. Its salts, which crystallize but imperfectly, are decomposed by much water. In alcohol, or a mixture of this solvent with ether, they readily dis- OF NICOTINA OR NICOTINE. 515 solve, but are insoluble in pure ether. The precipitate given by their aqueous solutions with iodine is saffron yel- low; that yielded with tannic acid, white. 5480. Coneia is coloured blood-red by nitric acid. By exposure to air it turns brown, and is resolved into ammo- nia, and a bitter, inodorous, resinous substance, which is not poisonous. Of Nicotina or Nicotine. 5481. The preceding name is given to the active poi- sonous principle, to which tobacco (nicotiana tobaccum) and some other plants owe their active qualities. For its elaboration, the means described as suitable for the elabo- ration of coneia may be used, though in either case mag- nesia, or any other alkaline earth, or alkali, might be sub- stituted for potash in the first step of the process. 5482. Pure nicotina or nicotine is a colourless oily liquid, endowed, in a high degree, with the odour and taste of to- bacco. It is soluble in water in all proportions, which is a property displayed by no other organic base. It is also soluble in ether or alcohol. When anhydrous, it emits white fumes at 212, and at 480 distils, undergoing, how- ever, a partial decomposition. Its distillation is accom- plished easily with the aid of water. 5483. Nicotina is highly alkaline, neutralizing and form- ing soluble salts with acids. Of these, some are crystalli- zable, retaining, however, the savour of tobacco. Sub- jected to alkalies, they evolve the characteristic odour of the plant.* 5484. Of Lobelina or Lobeline. It appears by an article in the American Journal of Pharmacy for April, 1841, Vol. 13, that Mr. Procter, jr., has obtained an organic alkali from the seeds of the lobelia inflata, by acidulated alcohol, displacement, ether, and evaporation. This alkali is repre- / * A new process for the evolution of nicotina is given in the Journale de Pharma- cie, for February, 1842, of which the steps are as follows : Maceration for 24 hours in water acidulated by sulphuric acid; expression, evaporation to a syrupy consist- ence; distillation with potash, water being added to prevent injurious concentration; neutralization by oxalic acid ; evaporation to dryness ; treatment with absolute alco- hol, which takes up oxalate of nicotina; evaporation, decomposition by potash; solu- tion in ether; evaporation, whence results nicotina free from all impurity, excepting water and alcohol in a minute proportion. Agreeably to M. V. Ortigosa, the author of this new process, nicotina forms compounds with chloroplatinic, and chlorohydrar- gyric acid. 66 516 ORGANIC CHEMISTRY. sented as having a great resemblance to nicotina, but as much less poisonous. Picrotoxine or Picrotoxia. 5485. The extremely poisonous principle of cocculus in- dicus has received the name of picrotoxine, but has not been conceived to have basic properties, nor to agree with the organic alkalies in holding nitrogen as an element. Nevertheless, in the late work of Liebig and Gregory, 1168, it is arranged among the organic bases, arid is al- leged to have been shown, by the recent researches of Mr. Francis, to contain 1.38 per cent, of nitrogen. Yet a new formula for picrotoxine had not been published by that chemist. 5486. I subjoin an account of the process for obtaining this alkali, and a description of its properties. 5487. The bruised cocculus indicus, after being sub- jected to pressure in order to expel as much as possible of their fat oil, are boiled in alcohol. The alcohol being se- parated from the matter which it takes up by distillation, this matter is redissolved in boiling water, slightly acidu- lated. From the resulting solution, on cooling, the picro- toxine separates in short, thin, colourless prisms, insuscep- tible of fusion. Picrotoxine is soluble in twenty-five parts of boiling water, and very soluble in alcohol. It is in- tensely bitter, and highly poisonous. Its formula is pro- bably C 12 H 7 O 5 N. Of Antiarine or Antiaria. 5488. The deadly poison to which the name of antiarine has been given, is in a predicament analogous to that in which picrotoxine has heretofore been placed. I mean that of resembling many of the organic bases in its acti- vity as a poison, while devoid of nitrogen, and of the abi- lity to react like a base. It is not, however, improbable, that further researches may prove the pretensions of an- tiarine to rank with the organic alkalies, both as to pro- perties and composition. Antiarine is the active principle of that most deadly upas poison, respecting which, highly exaggerated accounts were published about forty years ago, representing that the tree producing it could not, without loss of life, be approached, unless upon the wind- BASES FROM THE OIL OF MUSTARD. 517 ward side. Its formula is alleged to be C 12 H 10 O 5 . It crystallizes in small scaly crystals, soluble in 250 parts of cold water, 70 of alcohol, and 2790 of ether. Bases from the Oil of Mustard. 5489. Thiosinnamina. When the oil of mustard is brought in contact with three or four times its volume of strong ammonia, crystals are formed, which are purified by recrystallization. These are thiosinnamina : formula, C 8 H 8 N 2 S 2 . 5490. Thiosinnamina is soluble in hot water, less so in cold water, soluble in alcohol and ether. It has a bitter taste, and no smell. At 392 it is resolved into ammonia, and a resinoid basic compound not fully investigated. Thiosinnamina combines with acids, but its salts do not crystallize: it yields a chloroplatinate with chloroplatinic acid = C 8 H 8 N 2 S 2 HC Cl + Pt Cl; and with corrosive sub- limate a chlorohydrargyrate = C 4 H 4 NS Cl + Hg Cl. 5491. Sinnamina. This new base is obtained in the fol- lowing way: Thiosinnamina is digested with moist hy- drated protoxide of lead till all the sulphur is removed. The residue is then subjected to water, finally to alcohol. The resulting solution is evaporated to a syrup, which, after some time, deposits fine transparent crystals of sin- namina. 5492. Sinnamina is a powerful base, expelling ammonia from its salts, and precipitating the solutions of peroxide of iron, of copper, and of lead. It combines with acids, but yields no crystallizable salts. It is precipitated by chloro- platinic and chlorohydrargyric acid, and throws down sil- ver from its solution in nitric acid. When heated, it evolves ammonia, and leaves a basic resinoid matter. The production of sinnamina from thiosinnamina is ef- fected by the separation of all the sulphur with more or less hydrogen. I say more or less, since it is not known with certainty whether the formula of sinnamina is C 8 H 6 N 2 or C 4 H 3 N 2 . (Varrentrapp and Will.) 5493. Sinapolina. This compound, discovered by Si- mon, is obtained by depriving oil of mustard of its sul- phur, by the action of baryta or of oxide of lead. It is soluble in hot water and alcohol, and crystallizes in shining, fatty, fusible scales. Its solution has an alkaline reaction. It combines with acids, and may be separated 518 ORGANIC CHEMISTRY. from them by ammonia. When combined with chlorohy- dric acid, it precipitates the chloroplatinic and chlorohy- drargyric acids. It is generated from the oil of mustard by the abstraction of two atoms of bisulphuret of carbon, and the addition of two atoms of water. Thus C 16 H 10 N 2 S 4 + 2HO = C 14 H 12 N 2 O 2 + 2CS 2 . The formula of sina- polina is C 14 H 12 N 2 O 2 . Liebig and Gregory, 1156. 5494. Cinchovine is the name given by Manzini to a new alkali which he has extricated from a species of Peruvian bark, " cinchona ovata." It is obtained by a process analogous to that usually employed to obtain qui- nia. No statement is made respecting its efficacy. On this account, and because of the alleged inefficacy of the species of cinchona, from which it is derived, it may be inferred that cinchovine has little or no practical value, and will not merit that more should be said of it here. Comptes Rendu, 25, 125. 5495. Of Cisampelina or Cisampeline, also called pelosine. In his Re- port on Chemistry for 1841, Berzelius gives the following information re- specting this base, lately discovered by Wiggers. A filtered solution of the roots of cisampelos pareira, obtained by digestion in water acidulated by sulphuric acid, is saturated with carbonate of soda, avoiding to add an ex- cess. The precipitate twice washed, and well dried by filtering paper, and subsequent exposure to a heat of 212, is subjected to pure ether. Being taken up by this solvent, it is recovered from it pure and anhydrous by the distillatory process. 5496. Cisampelina, thus procured, is hard and brittle, and to the taste, sweetish bitter and nauseous. It has not been crystallized. It is to this principle that the medicinal properties of the cisampelos pareira are as- cribed. The alkali is called pelosine by Wiggers, its discoverer; but I concur with Berzelius, that the other appellation is preferable as recalling the idea of its source. 5497. Of Hederina, Surinamina, and Jamaicina. In 1824, Mr. Hut- tenschmidt alleged that he had discovered two bases in the "cortex geofFriae jamaicensis and surinamensis." Agreeably to Berzelius' report, the exist- ence of these bases has lately been confirmed by Wiggers. Vandamme and Chevalier, according to the same authority, have discovered a base in hedera helix. As no important efficacy is ascribed to these bases, I do not deem it necessary to notice them further. The same considerations have prevented me from noticing some other bases, of which accounts are to be found in the reports of the great Swedish chemist; and likewise melamine and ammeline, derived from melam, a product of the decomposition of sul- phocyanide of potassium. Of certain general characteristics of the Vegetable Alkalies distinguish- ing them from Inorganic Bases, and of those which distinguish them into several different sets. 5498. It is observed by Liebig and Gregory, that the organic bases re- quire less acid for saturation in proportion as they contain more oxygen; although it is well known, that the more the oxygen in an inorganic base, the greater the quantity of acid which its saturation requires. BASES FROM THE OIL OF MUSTARD. 519 5499. Agreeably to the same authority, the salts formed with aconita, atropia, brucia, cinchonia, codeia, conicina, delphinina, emetia, morphia, narcotia, quinia, strychnia, veralria, are precipitated white by an infusion of galls. The precipitate is a tannate, which, by exposure to the air, be- comes converted into a soluble gallate.* 5500. I will here quote from Liebig and Gregory the following arrange- ment of the alkalies, as I consider such generalization always instructive, and serviceable to the memory. 1. Volatile bases containing no oxygen. These are anilina and nicotina, to which may be added conicina, although it is not certain that this base is destitute of oxygen. 2. Bases derived from the oil of mustard. These are thiosinnamina, sinnamina, and sinapolina. 3. Bases of cinchona bark. These are quinia, cinchonia, and aricina. 4. Bases of the papaveracece, or the various species of poppy. These are morphia, codeia, narcotina, thebaina, pseudomorphia, narceia, and chelidonia. 5. Bases found in the solanacece, strychnacea, and other plants of the same kind. These are atropia, solania, jervina, brucia, strychnia, sabadillia, veratria, delphia, staphisia, menispermia, picrotoxia, emetia, corydalina, berbina, pi- perina, harmalina, caffeia, and theobromia. 5501. I have pointed out the inconsistency of supposing (5406), that when chlorohydric acid combines with an organic alkali, it can form a combination meriting to be called a chlorohydrate, while the compound which is engendered by the contact of this acid with ammonia is supposed to be ammonium; in other words, a chloride of the hydruret of that gaseous body. On the subject of iodine, Berzelius has urged that "a direct combi- nation of it with a vegetable alkali is as unlikely to exist, as would be a like combination with any other salifable base; and, moreover, experience shows, that such compounds are neither iodates, nor iodohydrates of the vegetable alkali." 5502. It must be evident, that whatever objections exist to assuming the existence of iodohydrates of organic bases, apply with equal force to the existence of chlorohydrates, bromohyd rates, fluohydrates, &c. &c. 5503. Agreeably to the representations of Berzelius, founded, in great measure, on the investigations of Bouchardat, the vegetable alkalies have, in common with ammonia, a propensity to combine with two atoms of io- dine, the recognised combinations consisting, not of an atom of iodine and an atom of the vegetable alkali, but of a compound of iodine and an iodo- hydrate of such an alkali. This view of the subject is alleged to be cor- roborated by the fact, that the combinations, with organic bases alluded to, are obtained, with pre-eminent facility, by a double decomposition conse- quent to the reaction of bi-iodide of potassium with a salt formed by an acid with one of these alkalies. The precipitates of the alkalies in question, thus obtained, are nearly insoluble, and in many instances well characterized. Hence the bi-iodide of potassium may be more confidently relied upon as a precipitant of the organic bases than tannic acid. From the precipitated * This does not altogether confirm the allegation quoted from O. Henry (5307, note), that tannic acid may be used as a general mean of precipitating, and thus ob- taining the vegetable alkalies. No suggestion is made as to any advantageous mer thod of extracting the alkali from the precipitate. 520 ORGANIC CHEMISTRY. compound of iodine with the organic base, the latter may be liberated by subjecting them in water to sulphydric acid. By these means the iodine is converted into iodohydric acid, after which, an inorganic alkaline base will separate the organic alkali in an isolated state. Berzelius' Report for 1840, p. 179. 5504. It may be proper to mention, that bi-iodide of potassium is formed by digesting iodine in a solution of iodide of potassium, usually erroneously designated in the shops as hydriodate of potash. The bi-iodide can only exist in solution, according to Berzelius.* Constitution of the Organic Alkalies. 5505. All the organic alkalies are constituted of hydro- gen, carbon, oxygen, and nitrogen, except melamine, nico- tina, and anihna, which are devoid of oxygen. 5506. It is remarkable that these alkalies contain a very large proportion of carbon, and that in all of them nitro- t * "Chloride of Gold as a test of certain Vegetable JlUcalics.MM. Larocque and Thibierge find, that perchloride of gold is a more decisive test of certain vegetable alkalies, than the double chloride of sodium and gold already employed for this pur- pose. The following are the colours of the precipitates which it produces with the salts of the annexed alkalies dissolved in water: Quinia, buff-coloured; cinchonia, sulphur-yellow ; strychnia, canary-yellow ; veratria, slightly greenish-yellow ; bru- cia. milk, coffee, and then chocolate-brown; morphia, yellow, then bluish, and lastly violet. In this last state the gold being reduced, the precipitate is insoluble in water, alcohol, the caustic alkalies, and sulphuric, nitric, or hydrochloric acids; but forms with aqua regia a solution which is precipitated by protosulphate of iron. " All these precipitates, with the exception mentioned, are very soluble in alcohol, insoluble in ether, and slightly soluble in water. They appear to be combinations of gold, chlorine, and the vegetable alkali, since their alcoholic solutions, treated with tannin, give a greenish-blue precipitate of reduced gold ; if the solution be filtered, and the alcohol be evaporated by heat, a precipitate of tannate of the alkali employed is formed. The liquor again filtered, gives with nitrate of silver a white precipitate insoluble in nitric acid, but soluble in ammonia. " Among the reactions of chloride of gold, those which occur with morphia and brucia, to the authors appear to be especially important, as they are sufficiently marked to prevent these alkalies from being mistaken for each other, and also yield pretty good characteristics for distinguishing brucia from strychnia. " The authors have also, as the results of their experiments, arrived at the follow- ing conclusions : " 1st. By the aid of reagents it is possible to determine the presence of morphia, strychnia, and brucia, in substances, which, after being mixed with the salts of these alkalies, have undergone the vinous, acetic, or putrefactive fermentation. M. Orfila has already shown that the putrefactive fermentation does not alter morphia. "2dly. Crystallized iodic acid, or a concentrated solution of this acid, is suscepti- ble of being decomposed by neutral azotized bodies; but a dilute solution of this acid cannot be decomposed by them, unless there be added concentrated sulphuric acid, crystallizable acetic acid, oxalic, citric, or tartaric acid. " 3dly. Iodic acid should not be employed as a test of morphia without the greatest caution. " 4thly. Perchloride of gold produces such effects with the vegetable alkalies, as serve to distinguish morphia, brucia, and strychnia, from each other. " Sthly. The reagents, on which the greatest reliance may be placed as tests of morphia, are nitric acid, neutral perchloride of iron, and perchloride of gold. " Gthly. By the use of reagents, morphia, which has been mixed with beer, soup, or milk, may be detected. " 7thly. It is also easy to prove, by reagents, the presence of meconic acid in soup or milk, especially when the meconate of lead is decomposed by dilute sulphuric acid," Journal de Chimie Medicale, Octobre, 1842 (5265). OF IMPORTANT NEUTRAL ORGANIC PRINCIPLES. 521 gen is likewise a constituent. It was at one time alleged, that agreeably to the analysis of Liebig, in an equivalent of any of the alkalies of this class, only one atom of ni- trogen could be found; but subsequent observation has shown that this rule has exceptions, since strychnia and brucia are found each to contain two atoms of the element in question ; and in some other organic bases, the propor- tion of nitrogen exceeds that of an atom to each equiva- lent. 5507. As morphia differs from codeia only in having one atom more of oxygen; and as the three alkalies of Peruvian bark differ only in the same way; quinia having one atom of oxygen more than cinchonia, and aricina one atom more than quinia, the idea has been suggested, that in either case a compound radical may exist, capable of different degrees of oxidation : hence morphia might be a bioxide, and codeia a protoxide, of the same radical; and in like manner cinchonia might be a protoxide, quinia a bioxide, and aricina a trioxide, of one radical. But were such the case when presented to chlorohydric acid, these oxides should severally have their basic oxygen replaced by as many atoms of chlorine, which is alleged not to ar- rive when the experiment is tried. They all form muriates, so called, under the circumstances alluded to, or chloro- hydrurets, agreeably to the view which I have taken re- specting their composition (5406). See Kane, 1078. OF IMPORTANT NEUTRAL ORGANIC PRINCIPLES. Of Salicin, a neutral Principle, and of some Compounds de- rived from it, or to the production of which it contributes. 5508. The discovery of an analogy, if not an identity, between the properties of the oil of gaultheria, and that of spirea ulmaria, induces the idea that there may be essen- tial oils in other vegetables of the United States, which may be worthy of examination. Under these circum- stances, every fact connected with the origin of the oil of spirea ulmaria, must be interesting to the lover of science. I have, therefore, deemed it expedient to give some details respecting salicin, the principle from which the artificial " hydruret of salycyl," saliculous acid, is extricated, and likewise of some substances resulting from the reaction of salicine with other bodies (5321, &c.). 522 ORGANIC CHEMISTRY. 5509. Salicin, C 42 H 23 O 16 + 6HO. This interesting principle, discovered by Le Roux and Buckner, is found in the bark and leaves of bitter willows, and in that of some species of poplar. It is obtained by subjecting the bark, in a divided state, to successive portions of boil- ing water. The resulting decoctions being united and concentrated by further ebullition, are, while boiling, min- gled with litharge gradually added until the liquor be- comes colourless. The lead, combining with the salicin, may be precipitated from it, together with various im- purities, by adding sulphuric acid at first, and^ then sul- phide of barium. With the aid of charcoal, and repeated crystallization, the salicin is obtained finally in delicate, silky white transparent needles, permanent in the air. It is bitter and inodorous, but without any reaction with ve- getable colours. It sustains no loss of weight at a boiling heat, but at a higher temperature is decomposed, becoming yellow, resinous, evolving inflammable vapour, and finally leaving a carbonaceous residue. It is soluble in five parts of cool water, and in any proportion in boiling water. It is no less s'oluble in alcohol, but is insoluble in ether, or the fixed oils. It forms with concentrated sulphuric acid a blood-red solution, which is blackened when heated. Any bark which contains salicin is liable to be reddened by contact with sulphuric acid. Salicin is thrown down from any of its solutions by acetate of ammonia. That saliculous acid is evolved by distilling salicin with sulphu- ric acid and bichromate of potash, has already been men- tioned (3066, 5320). 5510. Saliretine, C 30 H 15 O 7 + HO, is a resinous substance produced by boiling salicin either in diluted sulphuric, or chlorohydric, acid. It is soluble in caustic alkalies, excepting ammonia ; likewise in alcohol or ether, but is insoluble in water. By sulphuric acid it is changed to a blood-red ; and it seems likely that it is to the generation of this resin that the reddening of salicin by that acid is due. One atom of hydrated saliretine, with an atom of raisin sugar, comprise the elements of one atom of hydrated salicin. 5511. Chlorosalicine, C 42 H 25 Cl 4 O 22 . When a solution of salicine is im- pregnated with chlorine, a crystalline deposition ensues, which dissolves in water with difficulty, but in hot alcohol with ease. It may be considered as comprising the same elements as salicin, excepting the substitution of four atoms of chlorine for a like number of hydrogen. 5512. When during the impregnation, in the process above described, the temperature is raised to 140, a compound is obtained in which seven atoms of hydrogen have been replaced bv a like number of chlorine ; for- mula C 42 H 18 Cl 7 O 18 . OP IMPORTANT NEUTRAL ORGANIC PRINCIPLES. 523 5513. Rutiline. Under this appellation Braconnot designates a substance arising from the decomposition of salicine by concentrated sulphuric acid. Pure rutiline, when moist, appears at first reddish-brown, but soon becomes yellow ; when desiccated, its colour is brownish-black. It is friable, insi- pid, inodorous, and insoluble in water or alcohol. By inorganic acids its hue is changed to a beautiful red, by alkalies to a deep violet. 5514. Phloridzine, C 43 H 33 O 18 + 6HO. The preceding name has been given to a principle discovered by De Koninck in the bark of the roots of apple, pear, cherry, and plum trees. In composition and properties it is very analogous to salicin ; and differs, as respects elementary constituents, only in having two more atoms of oxygen. Phloridzine is extracted from any bark in which it may exist, by boiling alcohol of the specific gravity of .850. From the alcoholic solution thus obtained, it crystallizes on the re- moval of the solvent in delicate, colourless, silky, rectangular, prismatic needles; which are soluble in 1000 parts of cold water, and in every pro- portion in boiling water. The solution has an astringent, bitter savour, without any power to change vegetable colours. In alcohol it is also- solu- ble, but is insoluble in ether. At 212 it loses four atoms of water of crys- tallization. It melts at 320, but is not decomposed under 390. 5515. Phloridzeine, C 43 H 29 O 38 N 2 . This name is employed to desig- nate a substance obtained by the reaction of phloridzine with ammonia and atmospheric oxygen. As its name differs from that of this last mentioned substance only in the presence of an additional e, and conveys no idea of its composition, it seems very ill chosen. By simultaneous contact with at- mospheric oxygen and gaseous ammonia, moist phloridzirce is transformed into a red matter, which, readily dissolving in liquid ammonia, may be pre- cipitated therefrom by acids. The precipitate, thus obtained, is phlorid- zeine. It is formed by the addition of eight atoms of oxygen, and the ele- ments of two atoms of ammonia, to phloridziwe. An ammoniacal solution of phloridzeine, evaporated within an exhausted receiver, including some fragments of the hydrate of potassa, is converted into a purple blue resi- duum, having a cupreous metallic brilliancy. This residuum is unalterable in dry air, soluble in cold water, to which it communicates a magnificent purple blue. This solution is decolorized by deoxidizing substances, but resumes the oxygen thus lost, and the blue colour, on being re-exposed to the air. This blue residuum is compounded of an atom of phloridzeine, and an atom of ammonia. 5516. Asparagine, asparamide, altheine, agedoile. These are the syno- nymous appellations of a principle capable of forming a crystalline hydrate, C 8 H 8 O 3 N 3 + 2HO, which loses its water of crystallization at 248. It is found in asparagus, in liquorice, in the root of althea officinalis, in that of the potato, and various other plants. It crystallizes in large, transparent, right rhombic prisms. It has a cooling and somewhat nauseous taste, is soluble in water and diluted alcohol, but insoluble in this last mentioned liquid when concentrated, or in ether. By reaction with acids or alkalies, assisted by heat, asparagine is resolved into ammonia, and an acid called aspartic. The considerations which were mentioned as giving importance to caffein, must apply to asparagine as being a highly nitrogenated princi- ple, since such principles, without any very sensible activity, may, agree- ably to the suggestions of Liebig, be of importance in supplying the nitro- gen requisite to facilitate the functions of life. 5517. Taraxacine. Mons. Polex has extracted from the milky juice of the leontodon taraxacum, a crystallizable substance, which he has named 67 524 ORGANIC CHEMISTRY. taraxacine. The milky juice of the plant is boiled in distilled water, by which means the albumen is coagulated, involving the resin, fatty matter, and caoutchouc. The concentrated liquor is filtered, and allowed to evapo- rate spontaneously in a place moderately warm. The taraxacine crystal- lizes during this operation, and may be afterwards purified by repeated crystallizations from alcohol or water. It forms arborescent or star-shaped crystals. These melt readily, are not volatile, and have a bitter and rather acrid taste. They are sparingly soluble in cold water, but dissolve abun- dantly in boiling water, in alcohol, or ether. They dissolve in the con- centrated acids without being decomposed. Taraxacine contains no nitro- gen. 5518. When the albuminous precipitate, which has been separated from the water, is boiled in alcohol, a colourless substance, in the form of small cauliflower crystals, is obtained on the evaporation of the alcohol. On being dried it falls into a powder, very fusible, but difficult to be ignited. It is insoluble in water, but very soluble in alcohol and ether. The solu- tion has an acid taste, and yields no precipitate with acetate of lead. It is insoluble in the caustic alkalies. Berzelius' Report on the Progress of Science. Of certain Vegetable Principles devoid of Nitrogen. 5519. I have quoted verbatim, from Gregory and Liebig's new edition of Turner's Chemistry, 1118, the following account of vegetable principles de- scribed as devoid of nitrogen, and of a nature not yet fully ascertained; in hopes that some of my pupils may be induced, by their investigations, to endeavour to remedy the imperfection in chemical science thus admitted to exist. 5520. " Gentianine. Extracted by ether from the root of Gentiana lutea, and purified by solution in alcohol. It forms golden yellow crystals, of a very bitter taste, which may be sublimed. According to TrommsdorfF, when quite pure it is no longer bitter, and has acid properties, expelling car- bonic acid from the alkaline carbonates, and forming, with the alkalies, golden-yellow crystallizable salts. 55:21. " Santonine is found in the flowers of several species of Arte- misia, and in the so called Semen Cyncz, which is much used as a ver- mifuge, and is a mixture of the flowers, buds, and unripe seeds of these plants. Four parts of this mixture are digested with one-half of slaked lime and twenty of alcohol, at 90 per cent. The santonine is dissolved, in combination with lime and with a brown resin. It is separated by acetic acid, but is still contaminated with resin. This is removed by washing with a little alcohol; and the residue being dissolved in eight or ten parts of alcohol at eighty per cent., and boiled with animal charcoal, the liquid, on cooling, deposits santonine in colourless crystals, which must be kept in the dark, as they become yellow when exposed to light. It is tasteless and in- odorous, fusible and volatilizable, sparingly soluble in water, more easily in alcohol and ether. It has acid properties, and forms salts with potash and soda, the latter of which crystallizes. Acids dissolve it without altering it, and water precipitates from the solution the santonine unchanged. It forms crystalline salts with lime and baryta, and insoluble compounds with many metallic oxides. Its composition is represented by the formula C S H 3 O (Ettling); but its atomic weight must be twelve times greater, to judge from its capacity of saturation. OF VEGETABLE PRINCIPLES DEVOID OF NITROGEN. 525 5522. " Picrolichenine. Discovered by Alms in the lichen Vuriolaria amara, from which it is extracted by alcohol. It is purified from a green matter which accompanies it, by washing with a dilute solution of carbonate of potash. It forms obtuse double four-sided pyramids, which have a most intense bitter taste. When acted on by ammonia in a close vessel, it dis- solves; and after some time the solution becomes yellow, and deposits yel- low crystals, which are not bitter. When the arnmoniacal solution is ex- posed to the air, a dark red substance is formed, which indicates an analogy between this substance and orcine, which, as will be hereafter mentioned, occurs in other lichens. Its composition is unknown, but it contains no ni- trogen. It is said to be powerfully febrifuge. 5523. " Cetrarine is analogous to the preceding. It occurs in several lichens, as in Iceland moss, Cetraria Islandica, and in Sticta pvlmonacea. It is extracted by alcohol. It forms a fine white powder, very bitter to the taste. Concentrated hydrochloric acid colours it deep blue. Its other pro- perties are little known, but it is said to be used as a febrifuge in Italy. 5524. "Elattrine is the active principle of elaterium, the inspissated juice of the fruit of Momordica elaterium. The elaterium is dissolved in hot alcohol, and the concentrated solution thrown into water, which precipi- tates the elaterine. By repeating this process it is obtained pure. (Morries.) It forms delicate silky crystals of a very bitter taste. One-sixteenth of a grain acts as a drastic purgative. Its composition is unknown. It merits a more minute examination. 5525. " Colocynthine. The bitter and purgative principle of colocynth, which is the pulp surrounding the seeds of Cucumis colocynthis. It is ob- tained by evaporating the infusion made with cold water, at first in oily drops, which afterwards solidify into a brown, brittle mass. It is soluble in water, alcohol and ether, intensely bitter, and acts as a drastic purga- tive. Its chemical characters are imperfectly known, and it is probably a mixture. 5526. " Byronine. Obtained by a somewhat similar process from the juice of the root of Byronia alba and B. dioica. It forms a brown or yel- lowish-white mass, having a taste at first sweetish, then acrid and very bit- ter; soluble in water and alcohol, insoluble in ether. It appears to contain nitrogen, and is probably a mixture of several compounds. It is a drastic purgative, and has poisonous properties. 5527. " Mudarine is found in the bark of the root of Calotropis Mu- darii. (Duncan.) It is soluble in water and alcohol. The aqueous solu- tion gelatinises when heated to 95; at a higher temperature it is coagu- lated, the mudarine separating as a viscid mass. On cooling, it is slowly but completely redissolved. Mudarine has powerful emetic properties. 5528. " Scillitine. Obtained from the juice of squills, the bulb of Scilla maritima. A brittle mass, of a nauseous bitter taste. It acts as an emetic and as a purgative, and appears to be poisonous. (Tilloy.) 5529. " Cathartine. Similar to the preceding. Obtained from the leaves of Cassia Senna and C. lanceolata, and from some other plants. It has a bitter nauseous taste, and purgative properties. 5530. "Xanthopicrine is found in the bark of Xanihoxylum Clava Her- culis. It forms greenish- yellow silky crystals, intensely bitter and astrin- gent. It is very soluble in alcohol, and has neither an acid nor an alkaline reaction. Its action on the system has not been studied, but the bark is used as a remedy in the Antilles. 526 ORGANIC CHEMISTRY. 5531. " Columbine. Obtained from columbo, the root of Menispermum palmatum. It is extracted by alcohol or ether. Forms colourless and transparent oblique rhombic prisms, or delicate white needles: is neutral, fusible, and contains no nitrogen. It is very bitter, and becomes still more so when dissolved in acetic acid. It is the active principle of columbo. (Wittstock.) 5532. " Quassiine is the bitter principle of the wood of Quassia amara. When pure, it forms small white opaque prisms, which are intensely bitter, and very soluble in alcohol. From the analysis of Wiggers, its formula is probably C 20 H 12 O 6 . 5533. " Lupuline is the bitter principle of hops, the female flowers of Humulus lupulus. It is neutral, uncrystallizable, soluble in water and al- cohol, and very bitter. 5534. " Lactucine is the active principle of Lactucarium, the inspissated juice of Lactuca sativa, L. wrosa, and L. scariola. It forms yellowish indistinct crystals, which have a strong persistent, bitter taste. It is spa- ringly soluble in water, very soluble in alcohol. The anodyne effects of lactucarium are most probably to be ascribed to lactucine. 5535. "Ergotine. Discovered by Wiggers in the ergot of rye, Secale cornutum. It is obtained as a brown powder, of a pungent and bitter taste, and is conceived by Wiggers to be the active principle. He describes it as narcotic and poisonous; but its composition and properties are unknown, and it is most probably a mixture. 5536. " Porphyroxine. Discovered by Merck in Bengal opium. It forms small brilliant crystals, which, when dissolved in diluted mineral acids and heated, yield a red colour. It is neutral, soluble in alcohol and ether, insoluble in water. It is quite distinct from the other crystalline sub- stances found in opium, but as yet has been but little examined. 5537. " Saponine is found in the root of Saponaria ojficinalis and Gyp~ sophila Struthium. It is extracted by alcohol, and purified by repeated crystallization from that solvent. It forms a white brittle mass, not crys- tallizable. It has a taste at first sweetish, then acrid and irritating; and the smallest quantity of the powder introduced into the nostril causes violent sneezing. It is soluble in water; and the solution, even when very dilute, froths like a solution of soap. The root is used as a detergent. 5538. " Smilacine : Syn. Parilline, Salseparine. Extracted by alco- hol from Sarsaparilla (Smilax sarsaparilla). It is crystallizable, soluble in hot water and alcohol, colourless and tasteless. Its solutions have the property of frothing. Its formula appears to be C 15 H 13 O 5 . (Poggiale; Thubffiuf; Petersen.) The Chinova bitter of Winkler, found in China nova, has been shown by Buchner, jun., to be identical in its properties with smilacine; and Petersen has shown that its formula is C 15 H 13 O 4 , differing from that of smilacine only by 1 eq. of water. 5539. "Senegine: Syn. Polygaline, Polygalic Acid. Is found in Polygala senega and P. virginea. It is a white powder, at first tasteless, afterwards very acrid, and causing a feeling of astringency in the gullet. It also acts as a sternutatory. According to Quevenne, its formula is C 11 H 18 O 11 . 5540. "Guaiacine. Discovered by Trommsdorff in the wood and bark of Guaiacum officinale. It forms a yellow brittle mass, which has a sharp acrid taste. It is no doubt one of the active principles of the gum-resin of guaiacum, and is the cause of its acrid taste. 5541. Plumbagine occurs in the root of Plumbago Europcea. It is OP VEGETABLE PRINCIPLES DEVOID OF NITROGEN. 527 extracted by ether, and forms fine orange-yellow crystals, which at first have a sweet taste, followed by a burning acrid sensation. It is neutral, and soluble in hot water. Alkalies give to its solution a cherry-red colour, but acids restore the yellow. The root also contains a peculiar fat, not yet investigated, which gives to the skin a lead-gray colour, whence the name of the plant is derived. 5542. "Cyclamine: Syn. Arthanitine. Found in the root of Cycla- men Europaum. It crystallizes in fine white needles, of a burning acrid taste, and having emetic and purgative properties. 5543. " Peucedanine. Discovered by Schlatter in the root of Peuceda- num officinale. Extracted by alcohol. It forms delicate white prisms, fu- sible, insoluble in water, soluble in alcohol and ether. The solution has an acrid burning taste. It is neutral. Formula, C 4 H 2 O. In some roots that had long been kept, Erdmann found a modification of peucedanine, dif- fering from it only in being insoluble in ether. Its formula was C 8 H 4 O 3 ; which only contains one atom of oxygen more than the formula of peuce- danine doubled, and was, therefore, probably formed from it by the action of the atmosphere. 5544. " Imperatorine. Found by Osann in the root of Imperatoria Os- trutium. Is extracted by ether. It forms long transparent prisms, has an acrid burning taste, is neutral, fusible, insoluble in water, soluble in alcohol and ether. Formula, C 24 H 13 O 5 . . (F. Drebereiner.) 5545. " Tanghinine. Extracted by ether from the seeds of Tanghinia Madagascariensis after the fixed oil has been removed by pressure. It is crystallizable; soluble in water, alcohol, and ether; very bitter and acrid. It is also poisonous. (Henry and Ollivier.) 5546. " Meconine. Discovered by Couerbe in opium. It is dissolved, along with most of the other ingredients of opium, when water is used as the solvent ; and, being soluble in water, it remains dissolved when mor- phia, narcotine, &c., are precipitated by ammonia. Part of it, however, falls along with the precipitate. It is purified by the alternate action of al- cohol, water, and ether; in all of which it is soluble with the aid of heat. When pure, it forms fine white prisms, which are at first tasteless, after- wards acrid. It is fusible, and may be sublimed unchanged. It requires for solution 266 parts of cold water, and 18 parts of boiling water. When heated with water, it first melts into an oily fluid, and gradually dissolves. Sulphuric acid, diluted with half its weight of water, dissolves meconine, forming a colourless solution, which, when heated, becomes dark green. Water throws down from the green solution brown flocks, which dissolve in alcohol with a rose-red colour. From this alcoholic solution the salts of alumina, lead, and tin, throw down fine red lakes. Meconine is quite neu- tral. Its formula, according to Couerbe, is C 10 H 5 O 4 , or rather the half of this; but its composition cannot be considered as ascertained. By the ac- tion of chlorine it is converted into mechloic acid, and nitric acid changes it into nitro-meconic acid. 5547. " Cubebine. Found by Soubeiran and Capitaine in cubebs pep- per (the seeds of Piper Cubeba). It is neutral, crystallizable, tasteless, sparingly soluble in water and alcohol. Its formula is probably C 34 H 17 O 10 . 5548. " The following substances are neutral, have generally a bitter taste or are tasteless, and are to a certain extent problematical, as the ob- servations regarding them are very imperfect. It is probable that many of them will be found identical with some of the preceding. 528 ORGANIC CHEMISTRY. "Alcornine, from Alcornico, the root of Hedwigia mrgelioides. "Alismine, from Alisma Plantago. " Arnicine, from Arnica montana. " Asclepine, from the root of Asclepias gigantea. " Absinthiine, from the flowers of wormwood, Artemisia absinthium. " Antiarine, from Antiaris toxicaria. " Amanitine, from Agaricus muscarius, A. bulbosus, and others. " Buenine, from the bark of Buena hexandra. " Canelline, from the bark of Canella alba. " Cascarilline, from the bark of Croton Eleutheria. " Cassiine, from Cassia fistula. " Centaurine, from Erythrtea Centaurium. " Colletine, from Colletia spinosa. " Coriarine, from Coriaria myrtifolia. " Cornine, from the bark of the root of Cornus Jlorida. " Corticine, from the bark of Populus tremula. " Cytisine, from the seeds of Cyiisus Laburnum. " Daphnine, from the bark of Daphne Mezereum and other species. It is crystallizable. "Datiscine, from Datisca cannabina. "Diosmine, from the leaves of Diosma crenata. "Euonymine, from the seeds of Euonymus Europ&us. " Fagine, from Fagus sylvatica. " Fraxinine, from the bark of Fraxinus excelsior. " Geraniine, from the Geraniacece. " Granatine, from unripe Pomegranates. " Guacine, from Guaco leaves. " Hesperidine, from the spongy part of the Orange rind. Crystallizes. "Hyssopine, from Hyssopus officinalis. "IHcine, from 7/ea; aquifolium. Crystallizable. "Lapathine, from Rumex obtusifolius. " Ligustrine, from the bark of Ligustrum vulgare. " Lilacine, from Syringa or Lilac. " Liriodcndrine, from the bark of the root of Liriodendron tulipifera. " Me.nyanthine, from Menyanthes trifoliata. *' Melampyrine, from Melampyrum nemorosum. " Narcitine, from Narcissus pseudo-narcissus. " Olivile, from OZea Europ&a. " Olivine, from the leaves of O/ea EuroptBa. " Primuline, from the root of Primula veris. " Pyrethrine, from the root of Anthemis Pyrefhrum. " Populine, from the bark and leaves of Populus tremula. " Phillyrine, from the bark of Phillyrea media and latifolia. '* Rhamnine, from Rhamnus frangula. " Scordine, from Teucrium Scordium. ** Scutellarine, from Scutellaria lateriflora. " Serpentarine, from Aristolochia serpentaria. " Spartiine, from Spartium monospermum. " Spigeline, from the root and leaves of Spigelia anthelmia. " Tanacetine, from Tanacetum vulgare. " Tremelline, from Tremella mesentherica. "Zedoarine, from the root of Curcuma aromatica." OF ETHERS. 529 OF ETHERS, AND THEIR COMPOUNDS AND DERIVATIVES. Of Ethyl Ethers (3090). 5549. Agreeably to the classification proposed in treat- ing of ethyl (3077), common ether, the oxide of that com- pound radical, as the first in the class of simple ethyl ethers, is primarily to be the object of attention. Of the Oxide of Ethyl, common Ether, erroneously called Sulphuric Ether, C 4 H 5 O. 5550. It has been mentioned, that this compound is now called ether, on account of a sort of prescriptive claim, al- though the name by which it is designated has been ap- propriated to a class of bodies having, in common with it, some important characteristics (3083). 5551. Of the Properties of the Oxide of Ethyl. The ox- ide of ethyl is a colourless, transparent, volatile liquid, having only seven-tenths of the density of water, or seven- eighths of that of absolute alcohol. 5552. It is so inflammable, that a jet of it may be in- flamed throughout its whole length, when extending many feet. It has a fragrant smell and an aromatic taste, which, although pungent and stimulating, is not unpleasant. Its density to that of water at 60, is as 725 to 1000. It boils between 97 and 98, and congeals before it reaches the temperature of 47. With alcohol it unites in all pro- portions, but may be recovered therefrom by agitation with twice its bulk of water, which, combining with the alcohol, subsides gradually, allowing the liberated ether to form a superstratum easily separable. 5553. One part of ether dissolves in ten of water, and one part of this liquid in thirty-six of ether. Essential oils are soluble in ether to any extent, and also the margarine and olein of fixed oils; but stearine is so little soluble in ether, that it is employed to depurate it. of the two other above mentioned constituents of fat. Ether is likewise a solvent of most of the resins. It takes gold, in the metal- lic state, from a solution of the chloride of that metal, forming an ethereal solution, which has been employed to gild steel. It dissolves several of the haloid compounds, especially the chloride of zinc and bichloride of mercury; 530 ORGANIC CHEMISTRY. also several organic acids, the acetic, gallic, benzoic, oleic, and stearic, for instance. The solubility of various or- ganic alkalies in ether has been mentioned in treating of their extraction. Of sulphur, it takes up A of its weight; of phosphorus, from 7 V to aio-, according as it is more or less free from water. Bromine and iodine are copiously soluble in ether, the solutions being, however, liable to spontaneous decomposition, producing bromohydric and iodohydric acid, and some other products which have not been studied. 5554. According to Liebig, gaseous chlorine decomposes ether immedi- ately, each bubble inflaming spontaneously at the ordinary temperature of the air, giving birth to chlorohydric acid, and liberating carbonic acid. An- hydrous sulphuric acid, in the cold, generates from ether, isethionic, and ethionic acid, besides heavy oil of wine, light oil of wine (5537), and sul- phovinic acid. At a high temperature, these acids are resolved into heavy oil of wine, water, ether, sulphurous acid, and olefiant gas. 5555. Nitric acid, aided by heat, converts ether into formic, oxalic, and carbonic acid, together with aldehyde. 5556. Of chlorohydric acid gas, ether absorbs a large quantity ; and by distilling a concentrated solution, chloride of ethyl is generated. 5557. Dry alkaline hydrates have no reaction with pure ether at ordi- nary temperatures, but when moisture and oxygen are present and heat is employed, cause it to become brown after some time, and to form alkaline acetates or formiates. Potassium and sodium are alleged, by Liebig, slowly to deoxidize ether, and finally to decompose it into gaseous and oily carbo- hydrogens, forming oxides with which the ether combines as an acid. 5558. In presence of iron, lead, or zinc, with access of oxygen, this ele- ment is absorbed, generating acetates. 5559. Ammoniated ether may be obtained by subjecting ether, slaked lime, and chloride of ammonium, to the distillatory process. 5560. An etherial solution of the bi-iodide of mercury is obtained by the solution of one part of the bi-iodide in twelve parts of ether. One part of the bichloride of iron dissolves in four parts of ether. On agitating an aqueous solution of this bichloride with ether, this liquid takes the bichloride from the water, forming a golden-yellow liquor, from which light causes a crystalline protochloride to precipitate. 5561. In consequence of the solubility of narcotina, and insolubility of morphia in ether, it is employed to denarcotize opium in preparing it for making denarcotized laudanum. 5562. The tension of the vapour of ether being, per se, adequate to sup- port a pressure about half as great as that of the atmosphere, it conse- quently doubles the volume of any gas to which it may be added. This may be made evident by introducing a measured quantity of any gas into a volumescope, and adding, subsequently, a portion of ether* (818). * Agreeably to the experiments of Dalton, the vapour of any liquid in contact with the air, or any permanent gas, supports a proportion of the atmospheric pressure, which bears the same ratio to the whole pressure, as the height of the column of mer- cury, which the vapour in question will support, per se, in an exhausted receiver, is OF ETHERS. 531 6563. It was mentioned, in treating of olefiant gas, that when a volume of that gas was mingled with four volumes of hydrogen and two of oxy- gen, no condensation ensued when the mixture was ignited. The elements of the gas combining with those of water in the act of uniting, generated a new gas containing the elements of both. It was likewise mentioned, that half a volume of ether had about as much efficacy when substituted for the olefiant gas, as a whole volume of the latter. 6564. This is interesting, as tending to show that in the same space ether vapour contains about twice as much carbon and hydrogen as olefiant gas (1216). 5565. Of the Means of obtaining Ether. Respecting the means by which ether is elaborated, a general explanation has already been given in treating of ethyl (3804). The old recipe for its manufacture, was to distil two measures of officinal alcohol of about 0.840 with one of sulphuric acid, without any subsequent addition of alcohol ; but, latterly, the proportions have been nearly reversed by using, at the outset, nine parts of acid, by weight, with five parts of alcohol, the proportion of this liquid being sus- tained by subsequent additions, compensating the diminution resulting from the vaporization of the products. Liebig recommends, that in using these proportions, the alcohol be added to the acid in a copper or cast iron vessel, the liquids being mingled by stirring them with an iron spatula; but agree- ably to the experience of a manufacturer in this vicinity, who, for many years, was in the practice of distilling a large quantity of the etherifying materials at a time, it is preferable to introduce the alcohol into the alembic first, and then the acid, in a continued stream. This stream, by its supe- rior weight, produces a descending current, carrying along with it the alco- hol with which it comes into contact, and forming a compound, of which the boiling point is about 280. The descending current displacing the liquid previously near the bottom of the alembic, causes it to ascend at the sides, and thus establishes a circulation, by which a complete intermixture of the materials is effected. The heat generated meanwhile, acting upon some of the alcohol not in contact with the acid, is, in a greater or less de- gree, expended in vaporizing a portion of this ingredient, which, condensing in the receiver, should be restored to the body of the still or retort employed. This method of manipulation, to which I have myself long resorted, has se- veral advantages over that of Liebig; agreeably to which, the alcohol being poured over the acid, and in contact with the air, must sustain some loss by evaporation. The mixture being made in one vessel, and the distillation in another, causes unnecessary trouble, and the heat generated by combina- tion is lost, which, in the other case, requires little aid from the fire em- ployed to cause the distillation to commence. 5566. The most advantageous method of applying heat in this and many other cases, is that already described of a furnace having coals in a drawer which can be withdrawn in an instant, partially or wholly, so as to render the temperature perfectly controllable (963). Where carburetted hydrogen to the height of the mercury in the barometer at the same time. Hence, as the co- lumn which the vapour of ether will support, per se, at ordinary temperatures, is about half that of the usual height of the barometric column, it follows, that when liquid ether is introduced into any gas, its vapour relieves the gas of half the pressure, and at the same time deprives it of half the space, so that they require twice as much room as the gas required, per se ; consequently the volume of the mixture becomes twice as great as that of the gas previously. 68 532 ORGANIC CHEMISTRY. is supplied to a laboratory, from a gas light establishment, and a glass re- tort is to be used, a tube, forming a circle of four or five inches diameter, and perforated at intervals of about half an inch, so as to allow in its circum- ference from twelve to twenty gas lights, forms an efficient mean of apply- ing a competent and manageable heat. If the distillation of the etherifying materials be carried on until the resulting carbonaceous mass swells up so as to endanger its coming over, it will be found that the first products con- sist of ether with undecomposed alcohol, then ether and water, and after- wards ether with sulphurous acid and heavy oil of wine, forming a yellow liquid. But, according to Liebig, if before alcohol ceases to come over in a minute proportion, absolute alcohol be gradually added by a tube, with a very small aperture at the lower end, terminating under the surface of the mixture so as to keep it at the same level, by compensating the diminution resulting from the distillation, the evolution of ether and water continues without the extrication of sulphurous acid and oil of wine. If, says Liebig, " the operation be well managed, only ether and water will be evolved ; and the acid may serve for the preparation of ether, indefinitely, without per- ceptible diminution." When alcohol of the officinal density is used, in the way thus proposed, the acid soon becomes too much diluted to perform the office of an etherifyer. Liebig admits that when the spirit of wine employ, ed, contains 90 per cent, of anhydrous alcohol, only 31 parts can be etherified by 90 of sulphuric acid, and when the proportion of water to the acid exceeds the ratio of 9 to 2, ether cannot be evolved.* 5567. As respects the refrigeration of the ether vapour, as it comes over, I have been accustomed to employ an inverted open-necked bell-glass, through the axis of which a glass tube passes, being made to form an air-tight junc- ture with the neck, by means of a gum elastic bag, cut off near the bottom, so as to embrace the neck of the bell, while its own neck embraces the tube, being secured to both by ligatures. The beak of the retort is drawn out by means of a fire, and bent at right angles so as to descend into the upper orifice of the refrigerating tube. The bell is supplied with ice and water, this liquid being drawn off by a syphon as the ice melts, in order to allow more to be added. The refrigerating tube must terminate within a thin bottle, surrounded by ice and water. It is usually recommended to separate the ethereal portion of the product, and rectify it over milk of lime, or a * That sulphovinic acid is the inevitable consequence of mixing and heating sul- phuric acid with alcohol beyond a certain point, has already been mentioned in treat- ing of ethyl (3036) and of sulphovinic acid (5297). This combination arises probably from the affinity of hydrous sulphuric acid, sulphate of water, when undiluted, for etherine, and for more water, so that while one portion attracts the ether of the alco- hol, the other attracts the water. Agreeably to the representations of Liebig. above stated, if, during the etherifica- tion of alcohol by sulphuric acid, that ingredient be supplied in the proportion neces- sary to compensate the evolution of ether and water, a given quantity of acid may serve to etherify alcohol to an unlimited extent. The fact that, under such circum- stances, only the alcohol appeared to undergo decomposition, being noticed by Mi- cherlith, led him to infer that the part performed by the acid was merely catalytic. But this inference is irreconcilable with the well-established fact of the formation of sulphovinic acid whenever alcohol and sulphuric acid are mingled in due propor- tion and heated (5298). Yet, upon this view of the phenomena it is difficult to un- derstand how the mixture can at the same time evolve ether from one portion of the sulphovinic acid present, and yet absorb alcohol to form another portion of the same acid The most feasible explanation is, that the contact of the alcohol with the acid, in one part of the mixture, causes a reduction of temperature to the point at which the acid can combine with oxide of ethyl, while in other parts of the mixture, the temperature may be sufficiently high to cause other atoms of the same base to be disunited from the acid. OF ETHERS. 533 caustic alkaline solution, with the heat of a water bath of about 120. I have found ammonia the most speedy agent for this depurating process. 5568. Agreeably to the old process, oil of wine was generated towards the last. Hence, after the ether was distilled, a compound of alcohol and oil of wine remained, and could be brought over by raising the water bath to a boiling heat. Hoffman's anodyne liquor was thus obtained. Of heavy Oil of Wine, denominated by Liebig, "the double Sulphate of the Oxide of Ethyl and Etherole" the true Sulphuric Ether, C 4 H 5 O + C 4 H 4 -f- 2SO 3 : also of light Oil of Wine. 5569. When the proportion of sulphuric acid, in the mixture of this acid and alcohol employed to produce ether, becomes sufficient to retain the ether until the temperature rises above 324, a reaction ensues by which a yellow, sulphurous, ethereal solution of oil of wine comes over (3039) (5299). This consists of nearly equal parts of sulphurous acid and ether, the oil of wine being present only in a comparatively minute proportion. This liquid be- ing subjected to distillation at a heat not exceeding 120, the greater part of the ether and sulphurous acid may be brought over. The residue may then be exposed in vacuo over sulphuric acid and slaked lime. By these means all the sulphurous acid ether, and water, are absorbed, the oil of wine being isolated. 5570. Properties. Thus obtained, oil of wine has an unctuous consist- ency, whence its name. It is transparent, nearly colourless, and highly fragrant. Its taste has a resemblance to that of peppermint. 5571. Of the Composition of Oil of Wine. In the first instance, by Hennel, and afterwards more fully by Serallas, that kind of oil of wine which is designated as " heavy," was shown to be a chemical compound of sulphuric acid, carbon, and hydrogen. Subsequently, it was considered as a neutral hyd rated sulphate of etherine, 2C 4 H 4 + HO + 2SO 3 . This, of course, contains the same elements as if it were considered as an anhydrous neutral sulphate of the oxide of ethyl, 2C 4 H 5 O + 2SO 3 . Lately, it has been represented by Liebig, as a double sulphate of the oxide of ethyl and etherole; this last mentioned ingredient being, in other words, etherine, OH 4 . 5572. Oil of wine, thus defined, has been called heavy oil of wine, be- cause it sinks in water. It appears that it may be more or less deprived of its sulphuric acid, by being distilled from milk of lime, or by being digested with caustic alkaline solutions, and then forms what is called light oil of wine, being lighter than water. From the heavy oil, when free from water, I was unable to remove the acid entirely by distillation from potassium. 5573. When alcohol is etherified by chloride of zinc, two light oils are alleged to be evolved, one having the formula C 8 H 7 , the other C 8 H 9 . Being devoid of sulphuric acid, these oils are of course quite different from the heavy oil, of which the formula is above given. The allegations re- specting the composition of this heavy oil, are to me quite unsatisfactory, and lead to the impression that we are still ignorant of its true constitution. Nothing can be more anomalous, and inconsistent with the laws of chemical combination, with which experience has made us acquainted, than that two atoms of an acid, being comprised within a compound, and one of them in union with an oxidized radical acting as a base, as ether does, the other should refuse to unite with another atom of that base, and yet combine with a non- oxidized radical, etherole or etherine. In its free state, this last mentioned compound unites neither with sulphuric acid, nor any other acid, and yet 534 ORGANIC CHEMISTRY. it is represented as replacing the basic water, and completely neutralizing the acid properties of sulphoviriic acid, so that no immediate reaction en- sues on contact with the most powerful bases. It is unnecessary to repeat here the suggestions respecting the bibasic character of sulphovinic acid, made in treating of its inexplicable properties (5289). 5574. Of Hoffman's Anodyne Liquor. In consequence of the innova- tions made in the manufacture of ether, with the view of saving the acid, agreeably to the explanations above given (5566), the genuine anodyne li- quor of Hoffman, being no longer a collateral product of that manufacture, a mixture of ether and alcohol came to be substituted in commerce for the true medicine. This drew the attention of some of our older physicians, Dr. Wistar, and my late colleague, Dr. Physick. Dr. Wistar had remark- ed that the modern anodyne liquor did not produce any milkiness in water, when added to it, and he observed that the presence of this appeared es- sential to the efficacy of the medicament. In consequence of the request of Dr. Physick, having given some attention to the subject, I ascertained that in the officinal anodyne there was generally no oil of wine, and hence nothing to be separated on the addition of water. This phenomenon was found only to ensue in the anodyne prepared by those druggists who ad- hered to the old method of manufacture. As both by Drs. Physick and Dewees, much value was attached to the real anodyne " as highly useful in some disturbed states of the system, in tranquillizing and disposing to sleep," I regret that no efforts' have been made, by those who are in the practice of medicine, to ascertain whether there is any separate efficacy in the oil of wine, or whether it operates by giving greater permanency to the impression made by ether by lessening its volatility; and if this be the case, whether other essential oils cannot be used in lieu of oil of wine, as a ve- hicle for ether. 5575. A Process for making Hoffman's Anodyne. It has been men- tioned, that when the materials employed for the generation of ether have a certain ratio, and the temperature reaches a certain height, a yellow liquid comes over, which consists of heavy oil of wine, ether and sulphurous acid. This liquid being refrigerated by ice, and mingled, gradually, with ammo- nia, also refrigerated in a bottle surrounded by ice water, the ethereal solu- tion loses about half its bulk and weight. The residual liquid, which floats upon the resulting ammoniacal solution, being separated by dilution with twenty-four parts of alcohol, forms the anodyne liquor which I have been accustomed to prepare. Of Alcohol, or the Hydrated Oxide of Ethyl. 5576. In treating of ethyl, the theoretical composition of alcohol was, I trust, sufficiently explained (3069). I have now to treat of the means of obtaining it, and of its properties. 5577. Alcohol can only be obtained through the me- dium of the process called the vinous fermentation, being that by which the juice of the grape, of the apple, or pear, or infusions of sugar, or farinaceous substances, are ren- dered spirituous. By subjecting fermented liquors thus originating, to distillation, alcohol, diluted with water, and OF ETHERS. 535 flavoured by various peculiar empyreumatic oils, is ob- tained, being known as brandy, rum, or whiskey, accord- ingly as it may be derived from wine, from molasses, or from grain or cider. 5578. The vinous fermentation may be induced by the addition of yeast to a solution of sugar, kept between 60 and 70. During this process, a new distribution of the elements takes place, so as to form alcohol and carbonic acid. One atom of dry grape sugar, C 12 O 12 H 12 , is con- verted into two atoms of alcohol, 2(C 4 H 5 O + HO) and four atoms of carbonic acid, 4CO 2 . Two atoms of alcohol, C 8 H 12 O 4 With four atoms of carbonic acid, C 4 O 8 Form one atom of sugar, C 12 H 12 O 12 5579. It can hardly be necessary to mention, that the intoxicating power of the various liquids known generally in commerce as spirits, as well as that of wine, beer, ci- der, and other fermented liquprs, is due to the alcohol which they contain. These spirits, whether known as whiskey, gin, rum, brandy, or arrack, in a chemical point of view, may be considered as mixtures of water with al- cohol. Proof spirits is a term applied to any of these mixtures, when consisting of their principal ingredients in equal proportion. 5580. When, in consequence of the request of the Bri- tish treasury department, a committee of the Royal So- ciety undertook to make a table, showing the relation be- tween the density and the quantity of alcohol in a series of mixtures of this liquid and water, though the most scru- pulous accuracy was displayed, the conclusion was adopt- ed, that the matter existing in the various kinds of spirit, on which their diversity as respects flavour and value is dependent, was too small to require to be taken into ac- count. Nevertheless, it is well known that peculiar vola- tile oils accompany the whiskey obtained from grain and potatoes; and Ure alleges, that spirit obtained from da- maged grain, has been found to contain a peculiar volatile matter augmenting its intoxicating power, so as to produce in some persons a sort of frenzy. This matter, at the end of a few months, was spontaneously decomposed, so as to render the spirit less nauseous and unwholesome. The 536 ORGANIC CHEMISTRY. impression which has existed in this country, that peach brandy is more unwholesome than other spirituous liquids, may depend on an analogous cause. I am under the im- pression that brandy and rum contain principles which cause their peculiar flavour, and that the difference be- tween old and new spirit, is due to the modification of those essential oils on which the peculiarity of quality is in such cases dependent. 5581. By distilling one-half of the volume from proof spirit, officinal spirit of wine is procured, and by careful rectification, a liquid of the density 0.825 may be obtained, still containing eleven per cent, of water. But it is impos- sible for the vapour of any liquid to be formed in the pre- sence of another liquid, without becoming associated with a portion of its vapour. Besides, the inferior density of aqueous vapour creates in it a tendency to rise within the vapour of alcohol, as hydrogen does in atmospheric air. Hence the presence of two or three per cent, of water, it is alleged, makes the boiling point of alcohol lower. Con- sequently, a more aqueous portion distils first under these circumstances. But on the other hand, when the propor- tion of water reaches to six per cent., the result is invert- ed, so that the product, which first comes over, is less aqueous than the subsequent product. According to Gro- ning, if the capital of the still be kept at 174, no vapour which contains less than ninety per cent, of alcohol can pass over. Of course, the same object would be obtained, by passing the beak of one retort into the tubulure of ano- ther quite empty, and preserving the latter at a proper temperature, while its beak is made to communicate with a receiver properly refrigerated. 5582. Alcohol may likewise be concentrated by being subjected, in a well cleansed bladder, to the temperature of 122. The bladder is made more efficient by being smeared with a solution of gelatine, four times inside and twice outside. 5583. But to procure absolute alcohol, or, in other words, that which is devoid of water, a resort must be had to a chemical agent having a great affinity for water. Re- cently ignited carbonate of potash, quick-lime, or fused chloride of calcium, may be employed. In either case, the spirit must be kept in contact with the substance employed for some time before distillation. Chloride of calcium, re- OF ETHERS. 537 cently fused, is generally preferred. Of the spirit of wine of not more than 0.833 in density, and of the chloride of calcium, equal weights being mixed so as to form a satu- rated solution by the distillation of this and a well con- trived refrigerator, half the volume of absolute alcohol may be obtained. In this state it has a specific gravity, according to Ure, of 0.791 at 68. 5584. Alcohol has a very powerful affinity for water, so as to absorb it from the atmosphere, and from organic substances in general. It is by neutralizing water that it preserves anatomical preparations, performing, in this re- spect, a part analogous to that of brine. As the freezing point of mixtures of this liquid with water is extremely low when added to snow, it operates as deliquescent salt, and produces cold (419). The opposite effect results from its union with water, as it forms in that case a liquid, of which the capacity for heat is less than the sum of the capacities of its ingredients. Alcohol, by combustion, yields only water and carbonic acid. It is more expansible than wa- ter, and boils at 176. Its capacity for heat, whether in the liquid or aeriform state, is much less than that of water. It is a powerful solvent, and highly useful agent in pharmacy, and in the delicate analysis of vegetable and aninml matter. There is no satisfactory evidence that al- cohol has ever been frozen. The most intense cold pro- duced by solid carbonic acid and ether, by Dr. Mitchell, caused it to become syrupy in consistence, but did not freeze it. The addition of one-seventh of oil of turpentine will render the flame of alcohol so luminous, as to be a competent substitute for a candle flame. When alcohol is passed through a red-hot porcelain or copper tube, it is decomposed into water and carburetted hydrogen. Of EtherO'Sulphurous Acid, or Sulphurous Ether. 5585. Although no definite compound of sulphurous acid with the oxide of ethyl has been made, an affinity exists between this acid and oxide, re- sembling that between alcohol and water. Sulphurous acid boils at 12, ether at 98, the difference being 110. Of course, were not the affinity between these fluids more energetic than that between alcohol and water, of which the boiling point differs only by 36, they would not remain united at ordinary temperatures. The boiling point of sulphurous ether is lowered, in proportion as the ratio of the acid to the sulphuric ether is increased. When it contains oil of wine, the temperature necessary to ebullition of the aggregate, is inversely as the quantity of the sulphurous acid, and directly as that of the oil of wine, to the quantity of the other ingredient. Hence, 538 ORGANIC CHEMISTRY. although I have obtained sulphurous ether, which boils at 28, it is not pos- sible, with 'the heat of a boiling water bath, to separate the last portion of this ether from the oil of wine, since a part of the latter distils with it. I kept twenty-six measures of the compound of sulphurous ether and oil of wine in a glass measure, over water, for three weeks, without the slightest perceptible diminution of the quantity of the former. By means of a stop- ple secured by screws, about an ounce of the volatile sulphurous ether was kept in contact, with water for more than six weeks without apparent altera- tion. Even when in contact with ammonia, the transfer of the acid from the ether to the alkali takes place slowly, unless agitation be employed. 5586. Of Hyponitrite of the Oxide of Ethyl, Hyponitrite of Ethyl, Nitrite of Ethyl, Nitric Ether, Nitrous Ether, C 4 H 5 O + NO 3 . This ethereal compound is generated by the mixture of alcohol with nitric acid, provided the con- centration and proportion of the latter and the tempera- ture, be such as to prevent the reaction from being too violent; in which case the products are liable, according to Liebig, to be carbonic, acetic, and formic acid, with acetic and formic ether. This distinguished chemist omits to mention the residual elements of the nitric acid em- ployed. From the copious display of red fumes, there seems to be reason to infer that nitrous or hyponitrous acid is abundantly evolved. It is alleged by the same author, that when the reaction is sufficiently mitigated by the dilution of the reagents, and moderation of the tem- perature, only aldehyde and hyponitrous ether are gene- rated. 5587. Of this I presume the following rationale may be given: From an atom of the acid employed, two atoms of oxygen, uniting with two of the hydrogen of an atom of the alcohol, convert it into aldehyde. Meanwhile three atoms of oxygen, remaining united with one of nitrogen, in the state of hyponitrous acid, combine with an atom of the oxide of ethyl, expelling the water by which it was enabled to exist as alcohol. It follows, that at a minimum, one-half of the alcohol must be destroyed. 5588. According to Liebig, the best process for the ge- neration of this ether, in purity, is to impregnate alcohol with the vapour resulting from the reaction of nitric acid with starch, passing the aeriform proceeds through a well refrigerated tube to a receiver in a similar state. I have repeated this process twice, and have found a very small quantity of pure ether to be produced, with comparatively large consumption of the materials. OF ETHERS. 539 5589. I conceive that the best process is that of which I gave an account about four years ago, and which is as follows : 5590. Fourteen parts of the hyponitrite of soda with just enough water for its solution, seven parts of alcohol, eight of sulphuric acid diluted with twelve parts of water, are to be refrigerated, and introduced into a bottle immersed completely in water. In a very short time, hyponitrous ether will be seen swimming on the mixture; and after about six hours the pro- cess will be so far perfected, as to make it expedient to decant the ether. 5591. In lieu of including the materials within a bottle, as above de- scribed, the salt, previously dissolved in water, may be introduced into a tubulated retort, with a beak recurved and adapted to a refrigerating appa- ratus and receiver surrounded by ice- water, as already described. Through the tubulure of the retort, a tapering glass tube, terminating in an orifice of about a tenth of an inch in diameter, should descend nearly to the bottom, being secured air-tight to the tubulure by gum elastic or other lutings. 5592. The alcohol, acid, and water, being united and quite cool, may now be poured in through the tube; the ether rapidly generated is con- densed in the receiver in a state quite free from aldehyde. Water contain- ing a very little lime, potash, soda, or ammonia, may be used to free it en- tirely from acid, and quick-lime to free it from water. 5593. Hyponitrous ether, thus obtained, differs from the ether ordinarily known as nitric or nitrous ether, in having a more bland and saccharine taste, milder odour, and greater volatility. It boils below 65 F., and, by its spontaneous evaporation from the bulb of a thermometer, produces a cold of 15 3 below zero, F. Touched with the finger or tongue, it hisses as does water with a red-hot iron. 5594. If, after having boiled for some time, it be allowed to stand for a while at a temperature below its boiling point, the boiling will recommence at a lower temperature than that which was indicated by the thermometer when the boiling ceased. 5595. This seems to arise from the partial re-solution of the ether into an ethereal gas, which appears to be formed by the materials by which the liquid ether is generated, even when refrigerated below the freezing point. I have collected this aeriform ether, in large quantities, in bells over mer- cury. When subjected to great pressure, it condenses, more or less, into a yellow liquid, which produces, when allowed to escape into the mouth or nostrils, the same impression as the liquid ether. I have conjectured that this ether might be a compound of the liquid ether with nitric oxide gas, or that it may be isomeric with the liquid ether. Notwithstanding many ef- forts to obtain a liquid ether not resolvable partially into this gas, I have never succeeded. Hence the boiling point is extremely variable, as I have seen bubbles escaping below 40 from the liquid ether, when recently con- densed after distillation. 5596. In the production of cold by mixture with solid carbonic acid, Dr. J. K. Mitchell found this ether more efficacious than that commonly known as sulphuric ether, more properly called hydric ether. 5597. When the new ether, as it is first evolved, is distilled from pow- dered quick-lime, this earth imbibes an essential oil, which, with the aid of water, is yielded to pure hydric ether. Of course, it is easy to remove this solvent by evaporation or distillation. 69 540 ORGANIC CHEMISTRY. 5598. The odour of this oil seems to be an ingredient in that of ordinary nitric ether. Possibly the hyponitrous ether may resolve itself gradually into this oil and the gaseous ether, so that its boiling point may be probably varied by this chemical change. I suspect that the essential oil in question, is one of the impurities which causes the boiling point of the ether generated by nitric acid and alcohol, to be higher than the boiling point of that ob- tained, as in my process, by nascent hyponitrous acid. 5599. When the heat is raised, after the volatile ether ceases to come over from the materials above mentioned as producing it, ethereal products are distilled, of which the boiling point gradually rises as the process pro- ceeds. Meanwhile, the product thus obtained, becomes more and more acrid, till at last it is rendered insupportable to the tongue, as respects the after taste. On mingling these liquids with a solution of green sulphate of iron, the ether is all absorbed; but an acrid liquid, which causes the after taste, is not absorbed, and may be separated by hydric ether. The ether being vaporized by heat, the acrid liquid remains. The smallest drop of this liquid is productive of an effect upon the organs of taste and smell like that of mustard or horse-radish. 5600. The new ether, when secured in a glass phial by means of a well ground stopper, does not undergo any change by keeping in a cool situation for several months. A phial was suspended about fifteen feet below the surface of the ground, in a cistern of water, for about five months; another was left in a cool cellar for a longer period, without any apparent change of properties. In this case pressure prevented the escape of the ethereal gas as above mentioned. 5601. All the ethereal compounds, formed by the reaction of the oxacids of nitrogen with alcohol appear to be decomposable by green sulphate of iron. Under these circumstances, according to Berzelius, a malate of iron is formed from common nitric ether. 5602. Concentrated sulphuric acid absorbs the elements derived from the alcohol, and liberates nitric oxide gas, which is, it is well known, rapidly absorbable by the green sulphate above mentioned. Let there be three cy- lindrical glass jars, of such a ratio to each other in size, as to allow two in- terstices of about half an inch between the second or intermediate jar, and the outer and innermost jar; likewise, let two bell-glasses be provided, of such a size as that one of them may enter the inner interstice, while the other will cover and descend into the outer interstice. Let a wine glass, containing the ether, be placed in the innermost jar, and let the outer jar be supplied with green sulphate of iron, the other two with concentrated sul- phuric acid, and let the bells be put in their respective places. 5603. Under these circumstances, the ether will be gradually vaporized, and the alcoholic elements, with some oxygen, will be absorbed by the acid, while nitric oxide, being liberated, will pass into the sulphate, and be, con- sequently, absorbed. Of the Process for Sweet Spirit of Nitre. 5604. This name is applied to a dilute solution of im- pure hyponitrous ether in alcohol, which has acquired its name from being obtained by -subjecting nitre and sulphu- ric acid to distillation with a great excess of alcohol. The proportions, agreeably to the United States Dispensatory, OF ETHERS. 541 are two pounds of nitre, one and a half pounds of acid, nine half pints of alcohol, the product being rectified from a pint of proof spirit and an ounce of carbonate of potassa. The sweet spirit of nitre of commerce is a very uncertain article as to the nature and proportion of its ingredients, as I have been informed by eminent druggists, as well as physicians. By keeping, it becomes partially acidified, whereas I have kept pure hyponitrous ether in a cool cel- lar for nearly a year without deterioration. I am of opi- nion, that it would be advantageous if the prescriptions of our physicians were made with reference to ingredients of a high degree of purity. The physician should know how much real ether is contained in the diluted article which he directs his patient to use. Hence the pure hyponitrite or oxide of ethyl should be prescribed, adding as much al- cohol or water as may be deemed necessary. Agreeably to the present practice, it is in the power of manufacturing chemists to impoverish ethereal preparations with little danger of detection. 5605. Pursuant to the London Pharmacoposia, three ounces of nitric acid, by distillation with a quart of alco- hol, are allowed to produce twenty-four fluid ounces of sweet spirit of nitre. According to Thenard, the quantity of ether, when the materials are in the ratio of equality, amounts to two-thirds the weight of the acid. Hence it is probable, that the quantity of ether in twenty-four fluid ounces of sweet spirit of nitre, obtained as above men- tioned, is not more than two ounces. I infer that sweet spirit of nitre, of a more uniform strength, would be ob- tained by the addition of alcohol to pure nitric ether, to an extent no more than adequate to render it soluble in water, and then adding water to the alcoholic solution, until the ether should form ( only a twelfth of the aggregate. In a preparation thus made, the properties of the ether would not be unnecessarily associated with those of alcohol, as in the usual officinal preparation. Of the Perchlorate of the Oxide of Ethyl, or Perchloric Ether. 5606. This ether was discovered, in my laboratory, by Mr. Martin Boy6 and Mr. Clark Hare. 5607. It was obtained by subjecting about ninety grains of crystallized sulphovinate of baryta, with an equivalent proportion of perchlorate of ba- ryta, to the distillatory process, receiving the product in from one to two drachms of absolute alcohol. By complex affinity, the sulphuric acid of the 542 ORGANIC CHEMISTRY. sulphovinate dispossesses the perchloric acid of the baryta, while, at the same time, the last mentioned acid combines with the oxide of ethyl. 5608. The perchlorate of ethyl is a transparent, colourless liquid, pos- sessing a peculiar, though agreeable smell, and a very sweet taste, which, on subsiding, leaves a biting impression on the tongue, resembling that of the oil of cinnamon, but more acrid and enduring. It is heavier than water, through which it rapidly sinks. It explodes by ignition, friction, or percus- sion, and sometimes without any assignable cause. Its explosive properties may be safely shown, by pouring a small portion of the alcoholic solution into a small porcelain capsule, and adding an equal volume of water. The ether will collect in a drop at the bottom, and may be subsequently sepa- rated by pouring off the greater part of the water, and throwing the rest on a moistened filler, supported by a wire. After the 'water has drained off, the drop of ether remaining at the bottom of the filter may be exploded either by approaching it to an ignited body, or by the blow of a hammer. The violence and readiness with which this ether explodes is not surpassed by that of any other known compound. By the smallest drop, an open porcelain plate may be reduced into fragments, and by a larger quantity, to powder. In consequence of the force with which it projects the minute fragments of any containing vessel in which it explodes, it is necessary that the operator should wear gloves, and a close mask, furnished with thick glass-plates at the apertures for the eyes, and perform his manipulations with the intervention of a moveable wooden screen.* 5609. In common with other ethers, the perchlorate of ethyl is insoluble in water, but soluble in alcohol; and its solution in the latter, when suffi- ciently dilute, burns entirely away without explosion. It may be kept for a length of time unchanged, even when in contact with water; but the addi- tion of this fluid, when employed to precipitate it from its alcoholic solution, causes it partially to be decomposed. Potassa, dissolved in alcohol, and added to the alcoholic solution, produces immediately, an abundant precipi- tate of the perchlorate of that base, and, when added in sufficient quantity, decomposes the ether entirely. 5610. The perchlorate of ethyl has been subjected to the heat of boiling water without explosion or ebullition. 5611. It may be observed that this is the first ether formed by the com- bination of an inorganic acid containing more than three atoms of oxygen with the oxide of ethule, and that the chlorine and oxygen in the whole compound are just sufficient to form chlorohydric acid, water and carbonic .oxide with the hydrogen and carbon. It is also the only ether which is ex- plosive per se. Of Acetic Ether, or Acetated Oxide of Ethyl, C 4 H 3 O 3 -f O H 5 O. 5612. In common with other oxacid ethers, this ether may be obtained agreeably to the principles already set forth (5303), by distilling alcohol and sulphuric acid, or in other words, sulphovinic acid, with any acetate, or any sulphovinate with concentrated acetic acid. 5613. Acetic ether is colourless, burns readily with a pale yellow flame, has a refreshing odour, with a density of 0.890 at 60. It boils at 165, does not redden litmus, is soluble in seven parts of water, and in every pro- * For the particulars of the process I refer to the American Philosophical Transac- tions, Vol. 8, New Series-, also to Silliman's Journal, Vol. 42, for 1842, page 63. OF ETHERS. 543 portion in alcohol or ether. In general it is a solvent of all the substances which dissolve in this last mentioned liquid. By alkalies it is readily decomposed, likewise by sulphuric acid by which it is resolved into ether and acetic acid. Of Oxalic Ether, or Oxalated Oxide of Ethyl, C 4 H 5 O + O 4 H 3 O 3 . 5614. This ethereal compound, discovered by Thenard, may be obtained by the following process : Four parts of binoxalate of potash are mixed in a retort, with five parts of oil of vitriol, and four parts of alcohol, of 840, and briskly distilled. As soon as the product becomes turbid on the addi- tion of water, the receiver is changed. The subsequent product being quickly mixed with four times its bulk of water, the ether sinks to the bot- tom. It should be separated and washed with successive portions of water, till it becomes neutral to test paper. The ether thus washed is transferred to a small dry retort, filled up to nine-tenths of its capacity, and rectified. As soon as the product becomes clear, and the boiling goes on, regularly, the receiver is changed. What now passes over is pure anhydrous oxalate of the oxide of ethyl (oxalic ether) (Ettling). It is a colourless, transpa- parent, oily fluid, of sp. g. 1.0929 at 46, boiling at 370, miscible with alcohol and ether, and having a peculiar aromatic smell. In a state of pu- rity it may be kept many days under water, in which it is very sparingly soluble without decomposition; but when it contains but a minute proportion of free acid or alcohol, it is speedily decomposed into oxalic acid, which is deposited in large four-sided prisms, and alcohol. The same reaction ensues with an excess of fixed alkali. Of Carbonic Ether, or Carbonated Oxide of Ethyl, C 4 H 5 O -f CO 3 . 5615. Discovered by Ettling by the following means : Fragments of potassium being added to oxalic ether, duly warmed, as long as any gas is evolved and any excess of the metal removed, the resulting mass was sub- jected to distillation. Carbonic ether was generated, and being conveyed into the receiver, formed a superstratum upon the other products of the pro- cess. Being separated, and freed from water by the chloride of calcium, it was redistilled from potassium till, on contact with caustic potash, no ox- alate could be formed. 5616. Carbonic ether is colourless, ethereal, and very liquid, having an ardent taste, and an aromatic odour, resembling the ether from which it originates. It is lighter than water, has the specific gravity 0.975 at 66, boils at 260, and burns feebly with a blue flame. It may be mingled in all proportions with alcohol and ether, but is insoluble in water. When mixed with an alcoholic solution either of the hydrate of potash or soda, it is quickly resolved into alcohol and an alkaline carbonate, which separates in water as an oily concentrated solution, or forms as a crystalline powder, if no water be present. The formation of carbonic ether, which is attended by the production of several substances not yet examined, is still unex- plained. Formiated Oxide of Ethyl, or Formic Ether, C 4 H 5 O + C 3 H O 3 . 5617. To prepare formic ether, seven parts dry formiate of soda are dis- tilled with ten parts of sulphuric acid, and six of alcohol, of about 830. 5618. Formic ether is generated, and comes over for the most part with- out the application of heat. It is depurated of acid by milk of lime, and 544 ORGANIC CHEMISTRY. from water by chloride of calcium, which should be added so long as it be- comes moist (5281). 5619. Formic ether is a limpid liquid, of a penetrating, aromatic odour, being of the density of 0.912. It boils at 128. Its taste is cooling and spicy. It requires for its solution ten parts of water, but dissolves in all proportions in alcohol and ether, in pyroxylic spirit and several fixed -and volatile oils. It is acidified by exposure to air. OfBenzoated Oxide of Ethyl, or Benzole Ether, C 14 H 5 O -f C 4 H 5 O. 5620. This ether, discovered by Sheele, and analyzed by Woehler and Liebig, is generated by distilling a mixture of four parts of alcohol, of 830, two parts of crystallized benzoic acid, and one of concentrated, liquid, chlo- rohydric acid. As soon as the product renders water turbid, the receiver should be changed, as what passes over subsequently is benzoic ether. The ether, thus obtained, must be added to water to separate it, and be af- terwards boiled, with water and litharge, to remove free benzoic acid, and, lastly, digested with chloride of calcium. 5621. Benzoic ether is colourless, neutral, and very liquid, having an ethereal but suffocating odour, and provoking tears. Its specific gravity, at 50, is 1.0539. It'bpO* at 410, is soluble in alcohol and ether, but in- soluble in water. It is decomposed by chlorine, according to Malagutti, producing, among other products, chloride of benzule. Of the Tartrate and Citrate of the Oxide of Ethyl, and other "Salts" of Ethyl, so called, of minor importance. 5622. There are few oxacids which may not be united with the oxide of ethyl and other oxidized compound radicals, so as to form combinations in composition analogous to the complex ethers. Those formed with citric and tartaric acid, are hardly ethereal in their properties. The citrate re- quires a heat of 540 for ebullition, and is partially decomposed during dis- tillation. The tartrate, not being capable of neutralization, is more a con- gener of sulphovinic acid, viewed as a bibasic acid (5290), than of the com- plex ethers (3079). 5623. I shall forbear to treat of various compounds, analogous in com- position to those above described, whether having the oxide of ethyl, or any other oxidized compound radical, as a base, for reasons like those already given in relation to the acids (5397). Of (Enanthated Oxide of Ethyl, or (Enanthic Ether, C 4 H 5 O+C 14 H 13 3 . 5624. This liquid is called ethereal oil of wines, by Graham, which tends to confound it with the oil of wine, Liebig's sulphate of ethyl and etherole. It is alleged to be the cause of the characteristic odour by which wines are generically distinguished from dilute alcohol. It forms a portion of the re- sidue of the distillation of brandy from wines in the large way. It is said to constitute about one part in 40,000 of wine. The bouquet by which some wines are distinguished, ought to be ascribed to this ethereal compound. 5625. (Enanthic ether is a colourless liquid, having an intense odour of wine, almost intoxicating when plentifully inspired, and a strong disagree- able taste. It is soluble in ether and in alcohol, whether concentrated or dilute ; but not in water. Its density is 362 ; its volatility feeble. It re- quires a temperature between 434 and 446 for ebullition. This ether is instantly decomposed by fixed caustic alkalies ; but not by ammonia, or OF ETHERS. 545 alkaline carbonates. When distilled with caustic potash, it is resolved into alcohol, which comes over, and a very soluble oenanthate of potash. Gra- ham's Elements. Of Simple Ethers, formed by the Substitution of another Basacigen Body for Oxygen in the Oxide of Ethyl; or for the Hydrogen in the Water united with that Oxide. 5626. Chloride of ethyl, C 4 H 5 Cl, also called chlorohydric ether, for- merly, muriatic ether. It must be evident, from the comparison of the for- mula above given, with that of ether, C 4 H 5 O, that this chloride differs from that oxide, only in the substitution of an atom of chlorine for an atom of oxygen. 5627. Chloride of ethyl is generated by the distillatory reaction of chlo- rohydric acid, or various chlorides, either with the oxide of ethyl, with al- cohol, or any other of the compounds of that oxide, such as acetic, citric, oxalic, tartaric ether, &c. Agreeably to one process, alcohol is to be first saturated with chlorohydric acid gas; according to another, it should be distilled with an equivalent proportion of a strong aqueous solution of that acid, by means of a glass retort, communicating by a tube with some water, at a temperature of about 90 F., in a bottle with three orifices. Through one orifice, the tube proceeding from the retort enters, and is luted air-tight; into another orifice, a tube of safety is inserted; from the third orifice pro- ceeds another tube, arranged so as to communicate, through a refrigerating apparatus, with the interior of a phial surrounded by a freezing mixture. The water in the intermediate vessel detains any alcohol or acid evolved with the ether, which, in consequence of its greater volatility, reaches the phial. The product is freed from water and alcohol by digestion, for twen- ty-four hours, on chloride of calcium, cooled by ice-water. 5628. Chloride of ethyl is a colourless, ethereal liquid, with an aromatic, penetrating, and somewhat alliaceous odour. Its density is .874 at 41. It boils at 52; does not redden litmus; dissolves in twenty-four parts of water, producing a solution which has a fresh, aromatic taste. With solu- tions of silver it gives no precipitate. It burns with a bright flame, green at the border, evolving fumes of chlorohydric acid. In passing through an incandescent tube, it is resolved into equal volumes of that acid, and defiant gas. The exposure of this chloride to gaseous chlorine, aided by the solar rays, has given rise to a series of compounds. It is decomposed after some time, by the alkaline hydrates, into a chloride of the ingredient metals, and alcohol. 5629. Bromide of ethyl, C* H 5 Br, was discovered by Serullas, by dis- tilling a mixture of one part of bromine, four of alcohol, and one-eighth of phosphorus. It is a colourless liquid, denser than water, and very vo- latile. 5630. Iodide of ethyl, C 4 H 5 I, may be obtained by distilling alcohol, saturated with hydriodic acid gas. It is a colourless liquid, of the density of 1.9206. It boils at 161. 5631. Sulphide of ethyl, C 4 H 5 S, is formed by transmitting the vapour of chlorohydric ether, through an alcoholic solution of the proto-sulphuret of potassium; the chlorine being precipitated with the potassium, the sul- phur unites with the ethyl and is dissolved, or distils over, if kept suffi- ciently warm. It is a colourless liquid ; the boiling point, 135; density, 0.825 at 68. 546 ORGANIC CHEMISTRY. 5632. Sulphydrate of the Sulphide of Ethyl, or Mercaptan, C 4 H 5 S + HS. It might be advantageously called sulphalcohol, since sulphur performs in it the part allotted to oxygen in alcohol proper, sulphydric acid occupying the place of water, as may be perceived by the name and for- mula. 56.33. The best way to prepare this compound, discovered by Zeise, is to distil a solution of the sulphovinate of lime, of the density of 1.28, with a solution of sulphydrate of the sulphide of potassium, generated by satura- ting a solution of potash, also of the density of 1.28, with sulphydric acid gas. 5634. The product may be condensed by means of a refrigerating ap* paratus, like that mentioned as having been used for ether (5567). It may be purified from an excess of sulphydric acid, alcohol and water, by a second distillation from a small quantity of red oxide of mercury, and sub- sequent digestion with chloride of calcium. Mercaptan boils at* 100 near- ly, being a colourless, ethereal liquid, with a most penetrating and insup- portable alliaceous odour. Its density is said to be 0.835 at 70, an$ 0.842 at 59. It is soluble in alcohol and ether, but it is very slightly so- luble in water. The sulphydric acid of mercaptan reacts powerfully with metallic oxides, generating water, and a sulphide of the metal. This sul- phide remains in combination with the sulphide of ethyl, thus forming a class of sulphur salts. The oxide of mercury is instantly converted, by mercaptan, into a compound of this class, the mercaptide of mercury, C 4 H 5 S -f Hg S, which is a white, crystalline mass, soft to the touch, without odour, insoluble in water, and fusible, like wax, at 185. This mercaptide when distilled leaves cinnabar, and affords a volatile liquid, which has not been examined. The oxide of gold is also strongly acted on by mercaptan ; but other metallic oxides are less affected in proportion as they are more electro-positive. Thus, the hydrates of potash and soda have no sensible reaction with mercaptan. When gently heated, with nitric acid, mercaptan is converted into a new acid, which contains sulphide of ethyl, and the ele- ments of sulphuric acid, C 4 H 5 S 3 O 3 (Loewig, Kopp). 5635. Bisulphide of ethyl, C 4 H 5 S 3 . A transparent, oily liquid, which boils at 123.8, is obtained by distilling a mixture of sulphovi- nate of potash and the persulphide of potassium. It is decomposed by caustic potash, or by nitric acid (Zeise, Pyrame, Morin). 5636. Selenide of ethyl is obtained, according to Loewig, in the same way as the sulphide, substituting in the process, selenide of potassium for the sulphide of potassium. 5637. Telluride of ethyl, C 4 H 5 , a very volatile liquid, of a deep orange colour (Wheeler), may be obtained also by a similar process, using the tel- luride of potassium. 5638. Cyanide of ethyl, improperly called cyanhydric ether, = C 4 H 5 N, is a colourless liquid, with an insupportable odour of garlic, was obtained by Pelouze, by exposing a dry mixture of sulphate of ethyl and potash to a gentle heat, gradually increased. It has also been formed by distilling a mixture of sulphocyanide of potassium, alcohol, and sulphuric acid. It is a thick, oily liquid, of the density of 0.7, boiling at 179.6. OF ETHERS. 547 Of the Dehydrogenation and Oxidation of Ethyl, as con- tained in Ether or Alcohol, and of the Oxidation of the residual Products. 5639. The precipitation of carbon which gives a fuligi- nous character to the flame of essential oils and resins, has been ascribed to an inadequate supply of oxygen, and the superior affinity of hydrogen for oxygen, comparative- ly with carbon, at moderate temperatures. In consequence of this preference thus given, when some of the compounds of ethyl are subjected to oxidating agents, in processes below the temperature of ignition, more or less hydrogen is removed according to the intensity of the reaction. Thus, from alcohol C 4 H 5 O + HO, two atoms of hydrogen being taken, aldehyde is engendered, C 4 H 3 O + HO. These elements, by the absorption of one atom of oxygen, form an acid which has been called aldehydic acidj or acetous acid, C 4 H 3 O 3 + HO. Another atom of oxygen converts this acid into acetic acid, C 4 H 3 + O 3 + HO. Aldehydic acid has also been designated as acetows acid, having the same radical, and less oxygen than acetzc acid (3094). 5640. Acetyl, of which the formula is C 4 H 3 O, has been already described as a compound radical, indebted for its existence to the removal of two of the five atoms of hydro- gen belonging to ethyl (3093). Liebig attributes this re- sult to the oxidation of the ethyl ; but it is, as I conceive, a case of dehydrogenation of ethyl, resulting from the oxi- dation of two-fifths of its hydrogen. The relation between this radical and its progeny may be seen in the following table. Acetyl, - - C 4 H 3 Aldehydic, or hydrate of the oxide of ace- tyl, - C 4 H 3 O + HO. Acetous, or aldehydic acid, - C 4 H 3 O 2 + HO. Acetic acid, C 4 H 3 O 3 -f HO. No oxide of acetyl has been ascertained to exist uncom- bined with water and corresponding to common ether. Of the Hydrated Oxide of Acetyl, called Aldehyde. 5641. By inspection of the respective formulae, it will be perceived, that this compound differs from alcohol only 70 548 ORGANIC CHEMISTRY. in the loss of two atoms of hydrogen. Hence its name from the first syllable of each of the words alcohol and de- Aydrogenatum. Aldehyde is one of the products of the decomposition of alcohol, or ether, by passage through a tube at a low red heat: during etherification by nitric acid (5586): by platina wire in the lamp without flame, and in other cases. Liebig's process for the preparation of alde- hyde is as follows : Six parts of oil of vitriol with four of water ; four parts of spirits of wine and six of black oxide of manganese, are to be distilled with a very gentle heat, and the product collected in a receiver surrounded with ice-water. This process is completed as soon as the ma- terials in the retort cease to froth up. Kane observes that a purer product may be obtained by distilling two parts of spirits of wine with three of bichromate of potash, three of oil of vitriol, and six of water; the two last being previous- ly mixed and allowed to cool. To obtain aldehyde abso- lutely pure, it must be combined with ammonia; the result- ing crystallized ammoniacal compound must afterwards be decomposed by dilute sulphuric acid, distilled, by means of a water-bath at 120, with great care, and finally rectified over fused chloride of calcium. 5642. Aldehyde is a colourless, inflammable liquid, of a peculiar ethereal and suffocating odour. It boils at 72% has the density 0.790 at 64.40, and is soluble in water, alcohol and ether. By absorbing atmospheric oxygen, it is converted spontaneously into acetic acid. It dissolves phosphorus, sulphur and iodine. Aldehyde is capable of combining directly with ammonia and potash, thus evincing an approach to the acid character. 5643. Ammoniated Aldehyde, or the Hypoacetite of Ammo- nia, C 4 H 3 O, NH 3 -f HO. In this compound aldehyde ap- pears to act as an acid in entering into union with the oxide of ammonium (1106), so that it might be consistently de- signated as hypoacetous acid. Ammoniated aldehyde crys- tallizes in acute, colourless, transparent, brilliant, friable rhomboids, of a considerable magnitude, and which have an odour of spirit of turpentine. These crystals fuse be- tween 150 and 172, and distil without decomposition, at 212. They burn with a yellow flame. In the air, or even in closed phials, they turn brown, acquiring the smell of a burnt feather. Under pure ether they may be preserved, but not for a long time. These crystals are soluble in OF ETHERS. 549 water in all proportions, and more readily in hot than in cold alcohol. In ether they are but little soluble. 5644. Acetal, a compound of aldehyde with ether, C 4 H 5 O -f C 4 FPO -f- HO = C 8 H 9 O 5 , was discovered by Dobereiner, and described as oxy- genated ether. It is formed by the reaction of platinum black with the va- pour of alcohol, with the presence of oxygen. Acetal is a colourless liquid, having a peculiar odour, suggesting that of Hungary wines. It boils at 203 ; its density is 0.823 at 68. It is soluble in six or seven parts of water, and mixes with alcohol in all proportions. 5645. The crude formula of acetal being C 8 H 9 O 3 , two atoms of it will be found to contain the ingredients of three atoms of ether, and one of acetic acid. 5646. Resin of aldehyde is a product of the decomposition of aldehyde by alkalies, with the assistance of air. 5647. Elaldehyde. When pure anhydrous aldehyde is kept for some time at 32, while gradually losing its power to mix with water, it is trans- formed into a coherent mass of long, transparent, needle-shaped crystals, re- sembling spiculaB of ice. This is elaldehyde, which is similar in composi- tion to aldehyde, but of three times the atomic weight, judging from the density of its vapour. Elaldehyde fuses at 35.6, and boils at 201.2. 5648. Metaldehyde is another product of the condensation of the ele- ments of aldehyde, which appears in aldehyde left for some time in a well- stopped phial, in the form of white and transparent needles, or colourless prisms, which gradually attain a certain magnitude. It sublimes at 248, without fusing, and condenses in the air in snowy and very light flocks. It is insoluble in water, but dissolves easily in alcohol. Of some interesting Results of the substitution of Chlorine, Bromine, Sul- phur, and other Basacigen Bodies, for the Hydrogen or the Oxygen in the Compounds of Ethyl and Acetyl. 5649. Of the Chlorohydrate of the Chloride of Acetyl, Chlorine Ether, Bichlorine Ether, C 4 H 3 Cl + 01 H. Under the head "olefant gas" (1274), it was mentioned (1292) that olefiant gas received its name from its capacity of forming a liquid of an oily consistency, having an agreeable smell and taste. On account of its resemblance to ethereal compounds, as respects fragrance, solubility and taste, and the presence in it of two atoms of chlorine, it has been called bichlorine ether. Considering olefiant gas as a hydruret of acetyl, C 4 H 3 + H, the liquid in question is, by Liebig, treated of under the appellation at the head of this article, which indicates it to consist of chlorohydric acid, CH, and chloride of acetyl, C 4 H 3 Cl. 5650. This liquid is usually made by the confluence of equal volumes of moist chlorine and the gas above mentioned, within a large receiver, over water. Liebig recommends the reaction of the same olefiant gas with the perchloride of antimony, so long as there is any absorption. The resulting mass is to be subjected to distillation, till the product ceases to yield any ethereal liquid on the addition of water. The combination thus elaborated, requires to be depurated by redistillation with water, and subsequent agitation with sulphuric acid to depurate it of moisture. This ordeal is to be repeated until it ceases to be affected by sulphydric acid, or to emit chlorohydric acid during distillation. Finally, being successively washed with water, and kept in contact with chloride of calcium, it becomes quite pure. 550 ORGANIC CHEMISTRY. 5651. Thus obtained, the chlorohydrate of the chloride of acetyl is co- lourless, very liquid, and, as respects smell and taste, sweet and agreeable. It boils at 179. It maybe distilled, without decomposition, from the alka- line hydrates. It communicates its smell to water, although insoluble therein. In alcohol and ether it dissolves in all proportions. By an alco- holic solution of potash, it is decomposed into chloride of potash and chlo- ride of acetyl. It was by the exposure of this chlorohydrate to reaction with chlorine, in the sunshine, that Faraday (1*242) obtained the sesqui- chloride of carbon. 5652. Chloride of Acelyl. This is a gaseous product, of which men- tion is above made as resulting from the reaction of its chlorohydrate with potash, in alcohol. It has an alliaceous odour, and may be liquefied at the temperature of 6. 5653. Bromohydrate of Bromide of Acetyl, Bromide of Acetyl, lodo- hydrate of Iodide of Acetyl. Substances are described by Liebig, to which these names are given, which indicate their analogy with the two com- pounds of chlorine last described. 5654. Chloroplatinate of Chloride of Acetyl. By this name a com- pound has been designated, in which chloroplatinic acid takes the place of chlorohydric acid in the chlorohydrate of the chloride of acetyl. 5655. Oxychloride of Acetyl, C 4 H 3 Cl 2 O. This name has been given to a colourless oily liquid, which results from the saturation of anhydrous ether with chlorine, desiccated by being passed through concentrated sul- phuric acid. The formula of ether being C 4 H 5 O, two out of the five atoms of hydrogen are converted into chlotohydric acid, while two atoms of chlo- rine supply their place. Thus the oxychloride of acetyl is generated by a process analogous to that by which acetic acid is generated, oxygen per- forming, in one case, the same part as chlorine in the other. 5656. It must be evident that we have, in the formula of this compound as above given, the ingredients of acetyl combined both with oxygen and chlo- rine. It is therefore designated as an oxychloride, although usually this name has been applied to the union of an oxide and a chloride, each seve- rally combined with distinct atoms of the same radical. 5657. Oxysulphide of Acetyl, C 4 H 3 S 3 O. In this compound, sulphur occupies the place which chlorine fills in the oxychloride of acetyl, and of course that which oxygen fills in anhydrous acetous acid. The substitution of sulphur is effected by the reaction of the oxychloride of acetyl with sul- phydric acid; during which, the two atoms of chlorine uniting with the two of hydrogen, two atoms of sulphur supply the place of the chlorine thus re- moved. During this last mentioned reaction, another compound is formed, in which only one atom of the chlorine in the oxychloride is replaced by sulphur. The formula, of course, is C 4 H 3 Cl SO. The ethyl in acetic ether may, by reaction with chlorine, have its hydrogen so far replaced by chlorine as to be converted into an oxychloride, while its union with the acetic acid remains unbroken. Benzoic ether may not only have its base similarly changed, but the oxygen, forming its acid with benzule, may be re- placed by chlorine; so that for Bz O -f- C 4 H 5 O, a compound results, re- presented by Bz Cl + C 4 H 3 Cl a O. 5658. Chloroxalic Ether, C 4 Cl 5 O -f C 3 O 3 . This ether is created by the substitution of chlorine for the whole of the hydrogen in oxalic ether, of which the formula is C 4 H 5 O -f- C 3 O 3 . It will be seen, on comparing these formulae, that they differ only in this; five atoms of chlorine in one are sub- stituted for a like number of hydrogen in the other. It was obtained by OF ETHERS. 551 subjecting oxalic ether in a retort, surrounded by boiling water and exposed to the solar light, to a current of chlorine. 5659. Chloral,* C 4 H 3 O -f- HO, is the name given to a compound dis- covered by Liebig, in which all the hydrogen of aldehyde is replaced by chlorine. It might, with propriety, 1 think, be called hydrated oxide of chloracetyl, chloracetyl being understood to apply to the compound C 4 Cl 3 , which takes the place of acetyl as the organic radical. Chloral is the ultimate product of the dehydrogenation of anhydrous alcohol, by dry chlorine, and the substitution of three atoms of chlorine for five of hy- drogen. 5660. By subjecting, for twelve or fifteen hours, anhydrous alcohol to chlorine, dried by passage through sulphuric acid, a copious evolution of chlorohydric acid ensues, and a dense oily liquid is generated, which con- geals on cooling, being an impure hydrate of chloral. It is requisite to check the reaction in the first instance by immersion in water, afterward to assist by heat the expulsion of the chlorohydric acid. The hydrate is pu- rified first by heating it in a well-stopped flask, with nearly three times its bulk of sulphuric acid, when the chloral, depurated of water, forms a super- natant stratum. This being separated, and boiled to expel free chlorohy- dric acid, or alcohol, to remove any residual moisture, the chloral should be distilled from an equal volume of sulphuric acid. Finally, it must be rectified from lime, which, after being slaked, was rendered anhydrous by exposure to a bright red heat. 5661. Chloral, thus obtained, is a dense, oily, colourless liquid, greasy to the touch, having a penetrating, disagreeable odour, which provokes tears. Its taste is at first greasy, then caustic. It produces on paper an evanescent stain. Its density, at 64.4 is 1502; its boiling point is 201, nearly. It may be distilled without alteration. Its vapour is nearly five times as dense as that of air, its equivalent being four volumes. Chloral is miscible either with alcohol or ether. Aided by heat it dissolves sulphur, phosphorus, or iodine, apparently without alteration. OF METHYL ETHERS. Of the Oxide of Methyl, or Methylic Ether, C 2 H 3 O. 5662. In treating of the hypothetical compound radical, methyl, it was stated, that it was considered as performing, in the compound above mentioned, a part analogous to that which ethyl is inferred to perform in alcohol. 5663. The oxide of methyl is prepared by distilling one part of wood spirit, with four parts of sulphuric acid, the resulting gas being transmitted, successively, through a bottle containing milk of lime, and several bottles duly charged with pure water. In this liquid the gas dissolves, and being evolved by a boiling heat, may be collected over mercury. Oxide of methyl is an inflammable, colourless * The account of chloral, given under the head of inorganic compounds of carbon, being very brief, I have not hesitated to treat of it again, as an organic product, without reference to that imperfect notice. 552 ORGANIC CHEMISTRY. gas, of an agreeable ethereal odour. For liquefaction it requires a temperature below 3.2. Thirty-seven volumes of this gas dissolve in one of water. Alcohol, hydrated ox- ide of methyl, and concentrated sulphuric acid, take it up to a greater extent. From the latter it separates on dilu- tion with water. The density of the gas is, by experiment, 1605; by calculation, 1570; its combining measure being two volumes. 5664. By combining with the vapour of anhydrous sul- phuric acid, in a glass balloon, carefully cooled, the oxide of methyl forms a neutral sulphate. (Regnault.) Of Hydrated Oxide of Methyl, called Pyroxylic, or Wood Spirit, Methylic Alcohol, C 2 H 3 O + HO. 5665. In the process of purifying acetic acid from wood (5199), the crude acid is saturated by lime, and concentrated by distillation, of which the first product contains the crude wood spirit, which may be partially purified by repeated distillation from quick-lime; and is found in this state in commerce. It is still a heterogeneous mixture, containing, besides the hydrated oxide of methyl, which forms the larger part of it, acetone, and several other volatile and inflammable liquids. To purify the spirit in question, it is treated with an excess of chloride of calcium, in a retort, and distilled by a water-bath heat, which expels the more volatile liquids, and leaves the wood spirit in union with the chloride of calcium. A volume of water, equal to the volume of wood spirit employed, is then added to the re- tort, and the distillation continued. The spirit comes over imbued with a small quantity of water, from which it may be completely separated by subsequent distillation from quick-lime (5711, &c.). 5666. Wood spirit is a volatile, colourless liquid, simul- taneously recalling the taste and odour of acetic ether and alcohol. It is very inflammable, and burns with a pale flame. It mixes with pure water without becoming turbid, and likewise with alcohol and ether. Its density is 0.798 at 68; its boiling point, 140. The density of its vapour is, by experiment, 1120; by calculation, 1100; its combining measure or equivalent comprises four volumes. 5667. With the aid of heat, hydrated oxide of methyl dissolves small portions of sulphur and phosphorus, and may also serve as a solvent for the resins employed in OF ETHERS. 553 making varnishes. It mixes with volatile oils. Wood spirit is, like alcohol, acted upon by chlorine, peroxide of manganese or sulphuric acid, and by oxidizing agents in general, and yields analogous products. It is also decom- posed by potassium, with disengagement of pure hydrogen. 5668. Anhydrous barytes, although not soluble in alco- hol, dissolves in pure wood spirit, with much heat, and forms a compound, C 2 H 3 O HO + Ba O, which crystal- lizes in needles of a silky lustre. Lime is likewise soluble in wood spirit. 5669. Chloride of calcium dissolves eagerly in this sol- vent, so as to cause much heat. From a concentrated solution, it crystallizes in large, deliquescent, hexagonal tables, which contain two atoms of hydrated oxide of me- thyl, united with one atom of chloride of calcium. 5670. Neutral Sulphated Oxide of Methyl, C 2 H 3 SO 3 . This member of the methyl series, which has no analogous compound in that of ethyl, is generated either when oxide of methyl and anhydrous sulphuric acid are brought into contact, or when one part of the hydrated oxide is distilled with eight or ten parts of sulphuric acid ; the product being purified by washing with water, and distillation from chloride of calcium and quick- lime, successively. Sulphated oxide of methyl is a colourless liquid, of an alliaceous odour, of density 1.324 at 71. 6. It boils at 370. 4, and may be distilled without change. The density of its vapour is 4363.4 ; it con- sists of equal volumes of anhydrous sulphuric acid and oxide of methyl, condensed into one volume ; its combining measure being four volumes, the same as that of oxide of methyl. It is very slowly decomposed by water when cold, but rapidly when hot; the acid sulphated oxide of methyl and water being formed, while oxide of methyl is liberated. By double decom- position this compound may be employed in preparing all the other com- pounds of methyl. 5671. Acid 'Sulphated Oxide of Methyl, Bisulphated Oxide of Methyl, Sulphomethylic Acid, C 2 H 3 O + S 3 O 6 HO. This congener of sulphovi- nic acid, discovered by MM. Dumas and Peligot, and by Dr. Kane, about the same time, is formed by mixing concentrated sulphuric acid with hy- drate of oxide of methyl; or by dissolving the neutral sulphate in boiling water. Obtained by the latter method, and concentrated by evaporation, it is a colourless, syrupy, and very acid liquid ; which, in dry air, becomes a mass of white crystalline needles. It combines with bases forming double salts, in which the basic water of the acid is replaced by a metallic oxide. These double salts are soluble in water. 5672. Nitrated Oxide of Methyl, Me O NO 5 . To prepare this com- pound, one part of nitrate of potash, and a mixture of two parts of concen- trated sulphuric acid with one part of wood spirit, are introduced into a re- tort. The mass rises in temperature, and a liquid distils without additional heat. For its condensation, a refrigerated tube should be employed, termi- nating in a refrigerated flask. The heavier of the two liquids found in the flask is nitrated oxide of methyl, contaminated by a portion of a very vola- tile compound, supposed to be formiated oxide of methyl, which imparts the 554 ORGANIC CHEMISTRY. odour of cyanhydric acid. The product is rectified from chloride of cal- cium and from litharge. The last portions which distil over are perfectly pure. Nitrated oxide of methyl is a colourless liquid, of a weak, ethereal odour, which burns readily with a yellow flame; its density is 1.822 at 71.6, and boiling point 150. 8. Heated above 248, its vapour is decom- posed explosively, producing carbonic acid, water, and deutoxide of nitro- gen. This ether is soluble in water, and miscible in all proportions with alcohol, ether, and wood spirit. Of the Hyponitrite of the Oxide of Methyl, or Methylic Hyponitrous Ether. "Nitrite d 1 Oxide de Methyl" of Liebig, and others. 5673. In his late Treatise on Organic Chemistry, Liebig makes the fol- lowing statement: "The reaction which nitric acid exercises with the hy- drated oxide of methyl, is not like that which it exercises with alcohol, since, while this liquid is decomposed with great difficulty, giving birth to certain oxidized products and hyponitrite of the oxide of ethyl, the hydrated oxide of methyl is not altered by nitric acid, unless at a boiling heat. When a great excess of this acid is employed, formic and oxalic acid are generated, but no hyponitrite ("nitrite") nor nitrate of the oxide of methyl. It would seem, therefore, that the hyponitrite of the oxide of methyl does not exist." Traite, 552. 5674. Last winter, however, Dec. 1841, I found that by subjecting pure wood spirit to the process already described for producing the hyponitrite of ethyl, a congenerous ethereal product was obtained (5583). Hyponitrite of methyl has a great resemblance to its congener above named, in colour, smell, and taste; though there is still a diversity sufficient to enable a care- ful observer to distinguish one from the other. 5675. \^hen the process in which hyponitrous ether is generated, by in- troducing the refrigerated materials into a bottle surrounded by ice and water, was resorted to, substituting wood spirit for alcohol, it was found that the ether did not separate from the spirit as completely as in the process in which alcohol was the material. This I ascribe to the affinity between water and wood spirit being inferior to that between this last mentioned li- quid and alcohol. The boiling point of both of the ethers seemed to be nearly the same, and in both, in consequence of the escape of an ethereal gas, an effervescence resembling that of ebullition, was observed to take place at a lower temperature, than that at which the boiling point became sta- tionary. 5676. From the language of Liebig above quoted, I infer that previous efforts to produce the methylic hyponitrous ether had failed. The failure of others, and my success, cannot excite surprise, when the difference of the habitudes of wood spirit and alcohol, with nitric acid and alcohol, are taken into view, and the difference between my process and those followed in Eu- rope, by which more or less nitric acid is brought into contact with the spi- rit employed. When alcohol is presented to nitric acid, a reciprocal de- composition ensues. The acid loses two atoms of oxygen, which, by taking two atoms of hydrogen from a portion of the alcohol, transforms it into al- dehyde, while the hyponitrous acid resulting inevitably from the partial de- oxidizement of the nitric acid, unites with the base of the remaining part of the alcohol. But when pyroxylic spirit is presented to nitric acid, this acid, without decomposition, combines with methyl, the base of this hydrate: hence, as no hyponitrous acid is evolved, no hyponitrite can be produced. OF METHYL ETHERS. 555 Thus in the case of the one there can be no ethereal hyponitrite, in that of the other no ethereal nitrate. 5677. Oxalated oxide of methyl, C 3 H 3 O, C 3 O 3 , is a white, transpa- rent, and brilliant mass, composed of rhomboidal tables, which fuses at 123.8, and boils about 321.8. It is decomposed by water, and resolved into hyd rated oxalic acid and wood spirit. 5678. Formiated oxide of methyl is obtained by a process analogous to that for the formiated oxide of ethyl (5617), substituting pyroxylic spirit for alcohol. It is lighter than water, and boils between 96 and 100; its odour suggesting that of acetic ether. Reaction of Chlorine, Iodine, Cyanogen, and Sulphur, with Methyl and its Compounds. 5679. Chloride of Methyl, C 2 H 3 , Cl. This compound is produced by the reaction of chlorohydric acid with hydrated oxide of methyl : the rationale being the same as when this acid is presented to a hydrated metallic protox- ide. But it is best obtained, as are all the halogen compounds of methyl, by distilling the haloid salt, containing the halogen body with which the union is to be made, with a mixture of sulphuric acid and hydrated oxide of methyl: of course, in the case in point, chloride of sodium may be used. Chloride of methyl is a colourless gas, of an ethereal odour and sweet taste, having the density 1737.8 by experiment, and 1729 by calculation; the combining measure being four volumes. Water dissolves 2.8 volumes of this gas at 60. 8. It is not liquefied by a cold of 0.4. It should be re- membered that the chloride and oxide of methyl, are both much more vola- tile than the chloride and oxide of ethyl (873). 5680. Iodide of Methyl, C 2 H 3 !. This is a colourless liquid, which inflames with difficulty, and boils between 104 and 122. Its density is 2.337 at 69.8. 5681. Fluoride of Methyl, C 3 H 3 F, is obtained by distilling sulphated oxide of methyl with fluoride of potassium. It is a colourless gas, of which the density is 1186 ; and, for the solution of which, fifteen volumes of water are requisite. 5682. Cyanide of Methyl, C 3 H 3 Cy, is an ethereal liquid, insoluble in water. 5683. Sulphide of Methyl, C 3 H 3 S, is a very limpid liquid, of which the odour is extremely disagreeable. Its density is 0.845 at 69.8, and its boiling point 105. 8. The density of its vapour is by experiment 2115, by theory 2158 ; its combining measure being two volumes. Sulphide of methyl is formed by double decomposition, when chloride of methyl is transmitted through an alcoholic solution of p^rotosulphide of potassium. 5684. Sulphydrate of the Sulphide of Methyl, or Methylic Mercaptan, is a colourless liquid, lighter than water, which boils at 69 3 .8 and acts on oxides of mercury and lead like sulphydrate of sulphide of ethyl. 5685. Compounds having methyl for their radical, correspond so closely with those in which ethyl sustains the 'same character, that knowing the history of one class, it is easy to imagine the properties of the other. An- hydrous metallic salts do not alter them, while the hydraled alkalies disen- gage hydrated oxide of methyl from them with great facility. 5686. Chlorine decomposes the gaseous oxide of methyl, forming chlo- rohydric acid, and the following products, as observed by M. Regnault: Monochlorinated oxide of methyl, - C 3 H a Cl O 71 556 ORGANIC CHEMISTRY. Bichlorinated oxide of methyl, - C 3 H Cl 2 O Perchlorinated oxide of methyl, - C 3 Cl 3 O 5687. Chlorine is absorbed with great avidity by hydrated oxide of me- thyl, a heavy oil being generated, which has not been well examined. 5688. The reaction of chlorine with chloride of methyl, is the source of a series of compounds, in which, generally, the proportion of chlorine in- creases as the reaction is prolong Chloride of methyl, - C 3 H 3 Cl Monochlorinated chloride of methyl, - C 2 H 3 Cl Bichlorinated do. (chloroform), C 3 H Cl 3 Perchlorinated do. C a Cl Cl 3 5689. The monochlorinated chloride of methyl has an odour which is very sharp, but is, in other respects, similar to the oil of olefiant gas. Dis- tilled with an alcoholic solution of potash, a trifling precipitate of chloride of potassium is formed, and it comes over unchanged. 5690. The perchloride of carbon, C 3 Cl 4 , which is named, above, per- chlorinated chloride of methyl, is not altered by a solution of sulphydrate of potassium. It is decomposed by heat, yielding different chlorides of car- bon according to the temperature. 5691. At a low red heat, this chloride, C 3 Cl 4 , appears to be converted into another chloride of carbon, C 3 Cl 3 , supposing the combining measure of the latter to be four volumes, its density being 4082. This new chloride of carbon must therefore be isomeric with Faraday's sesquichloride, C 4 Cl 8 , but of only half the density. When decomposed at a higher temperature, it gives small silky crystals, constituting the chloride of carbon of Julin, C Cl. Lastly, at a bright red heat, the liquid chloride of carbon, C 4 Cl 4 , is the product. 5692. Chlorine acts readily upon the sulphide of methyl, and upon the compounds of the oxide of methyl with acids, constituting the compound methylic ethers. A benzoate and acetate of an oxychloride of formyl have been produced, having the following formulae : C 3 H Cl 3 O + Bz 0. C a H Cl 3 O + Ac O. From a mixture of iodine, nitric acid, and wood spirit, left to itself for a long time, yellow crystals are deposited. Bromine, under the same circum- stances, yields a heavy oily liquid. Of Formyl Ethers. 5693. Hydrated oxide of methyl, when brought into contact with plati- num black and atmospheric air, is converted into pure formic acid, by the substitution of two atoms of oxygen for two of hydrogen. The change ef- fected is, therefore, perfectly similar to that by which alcohol is, by the same agent converted into acetic acid. Oxide of methyl, formula C 3 H 3 O -f HO and 4O, is equivalent to formic acid, C 3 HO 3 + 3HO. Hence the inference, that formic acid contains a radical formyl, C 3 H, to which it has the same relation as acetic acid has to acetyl: acetic acid, C 4 H 3 + O 3 ; formic acid, C 3 H -f O 3 (4019). 5694. Formyl is the hypothetical radical of the following compounds: Hydrated oxide of formyl contained in methylal, C 3 HO -f HO Anhydrous formic acid, - * C 3 HO 3 OF FORMYL ETHERS. 557 Hydrated formic acid, - - - - C 9 HO 3 + HO Perchloride offormyl (chloroform), - - C a H Cl 3 Perbromide offormyl, - - - C 3 H Br 8 Periodide offormyl, - - - - - C 3 H I 3 Of Methylal, C 8 H 8 O, a Compound of Hydrated Oxide of Formyl, with Oxide of Methyl. 5695. By distilling two parts of wood spirit with two parts of peroxide of manganese, and three parts of sulphuric acid, diluted with three parts of water, Dr. Kane obtained a substance mixed with several other bodies, which he named formomethylal. It was considered a tribasic formiated oxide of methyl, but was afterwards shown by Malaguti to be a mixture of formiated oxide of methyl and a particular substance which he named me- thylal. To purify the methylal from the formiated oxide of methyl, the latter must be decomposed entirely by hydrate of potash. 5696. Methylal is an ethereal, colourless liquid, of a very agreeable aro- matic odour; which is miscible with three parts of water, and may be sepa- rated from that liquid by chloride of calcium, or hydrate of potash. It is very inflammable, and burns with a white flame. The density of methylal is 0.8551 ; its boiling point 107.6; its combining measure contains four vo- lumes. Methylal may be represented as a compound of one atom of hy- drated oxide of formyl with two atoms of oxide of methyl = C 2 HO, HO -f 2C 2 H 3 O. Regnault has explained its formation, by supposing that three atoms of oxide of methyl, formed by the action of sulphuric acid upon hyd rated oxide of methyl, group together so as to form a single molecule = C 6 H 9 O 3 . This molecule, by exposure to peroxide of manganese, loses one atom of hydrogen, gaining one of oxygen, so that the compound C 6 H 8 O 4 results. The formation of acetal, which corresponds with methylal in the acetyl series, is explained by Regnault in the same manner. 5697. Artificial Oil of Ants, C 5 H 3 O 3 (Stenhouse). This name was applied, by Dobereiner, to an oil generated during the preparation of formic acid. It was obtained by Dr. Stenhouse in larger quantity than it is pro- duced during the ordinary process, by distilling a mixture of equal weights of oat-meal, or saw-dust, and sulphuric acid diluted with its own bulk of water. In the process for formic acid, the peroxide of manganese cannot be omitted without greatly reducing the product; but in the process in ques- tion it should be left out. When oil of ants is purified, the taste and smell are very pungent and aromatic, resembling that of oil of cassia. It burns very readily with a bright yellow flame. Its density is 1.1006 at 80.6; its boiling point 334.4. It is soluble in water, but more so in alcohol and ether. It is decomposed by potassium with effervescence ; but neither the aqueous nor the alcoholic solution of potash is affected by it. Compounds of Formyl with Chlorine, Bromine, Iodine, and Sulphur. 5698. Protochloride of Formyl, C 2 H Cl. One of the substances which Regnault obtained by the reaction of chlorine with chloride of acetyl, name- ly, C 4 H 3 Cl 3 , is considered by Liebig as the protochloride of formyl, its atomic weight being divided by two. 5699. Bichloride of Formyl, C 3 H Cl 3 . According to Liebig, of one of the combinations, generated by the reaction of chlorine with the chloride of ethyl, the formula is C 4 H 3 Cl 4 . This being divided by two, gives that of the bichloride, as above stated. 558 ORGANIC CHEMISTRY. 5700. Perchloride of For my I, Chloroform, C 3 H Cl 3 . This compound may be made, by exposing a mixture of chloride of methyl, C 2 H 3 Cl, and chlorine to the direct rays of the sun; by distilling chloral with barytic water, or milk of lime, but more conveniently by distilling a dilute solution of hypochlorite of lime, or bleaching salt, with acetone, alcohol, or wood spirit. For this purpose, one part of slaked lime is suspended in twenty- four parts of water, and impregnated with chlorine till the greater part of the lime is dissolved. The lime must be in sufficient excess, however, to render the liquid slightly alkaline. When the solution of hypochlorite thus made has become clear, ^ T of its volume of alcohol should be added. The aggregate, having been allowed to rest for twenty-four hours, is to be subjected to the distillatory process, at a gentle heat, by means of a capa- cious retort. The product, consisting of perchloride of formyl, mixed with alcohol, being agitated with water, the perchloride separates as a dense li- quid, and may be obtained perfectly pure by digesting it upon chloride of calcium, and rectification with concentrated sulphuric acid. 5701. Perchloride of formyl is a colourless, oily liquid, of an agreeable ethereal odour, and sweetish taste; its density is 1.480 at 64.4; its boiling point, 141. 44. It is difficult to inflame, but burns in the flame of a lamp, imparting a green colour. An alcoholic solution of potash converts it into formiate of potash, and chloride of potassium, on which the name chloro- form is founded, Fo Cl 3 and 4 Po O = Po Fo O 3 and 3 Po Cl. The den- sity of its vapour is, by experiment, 4200; by calculation, 4116; its com- bining measure is 4 volumes. Chloroform may be distilled from sulphuric acid, potassium, or potash, without being sensibly altered. Exposed with chlorine to the direct rays of the sun, it is decomposed, and converted into chlorohydric acid, and a particular chloride of carbon, C 3 Cl 3 , which boils at 172. 4, and of which the density of the vapour is 5300, and combining measure four volumes. This chloride results from the substitution of chlo- rine for the whole of the hydrogen and oxygen in formic acid, C 2 Cl -f Cl 8 ; while the well known sesquichloride of carbon, C 4 Cl 3 -f Cl 3 , is similarly derived from acetic acid. 5702. When the above described chloride of carbon is made to pass in vapour through a porcelain tube, at a low red heat, it is resolved into two new chlorides of carbon, of one of which the composition is C Cl, while of the other the composition is C Cl 3 , according to Regnault. 5703. Chlorohydrate of the chloride of formyl, 2 C H Cl H Cl, is one of the products of the reaction of chlorine, with the chlorohydrate of the chloride of acetyl. 5704. Perhromide of formyl, bromoform, C 3 H, is prepared like the per- chloride, and very analogous to it in properties. Its density is 2.10. It is less volatile than the perchloride, and more easily decomposed by alkalies. 5705. Periodide of formyl, idoform, C 3 H I 3 , is a yellow, volatile sub- stance discovered by Serullas, which is often described as an iodide of car- bon. To obtain it, an alcoholic solution of potash is added to a solution of iodine in alcohol till the last is decolorized, carefully avoiding any excess of the alkali. The alcohol being allowed to escape by gentle evaporation, the iodide of formyl is deposited in crystals, which are purified from iodide of potassium by washing with pure water. This compound results from the reaction of one atom of alcohol, with six atoms of potash and eight atoms of iodine, by which one atom of periodide of formyl, one atom of formiate of potash, five atoms of iodide of potassium, and four atoms of water, are formed. OF XYLITE, OR LIGNONE. 559 1 atom of alcohol, 8 atoms of iodine, 6 atoms of potash, C 4 H 6 O I 8 Po 8 1 atom ofperiodide of formyl, - - C 3 H I 3 1 atom of formiate of potash, - C a H O 4 Po 5 atoms of iodide of potassium, - - - I s Po 5 4 atoms of water, H 4 O 4 C 4 H 6 O 8 1 8 Po 6 5706. lodoform crystallizes in brilliant yellow plates: has a character- istic odour suggesting that of saffron ; is insoluble in water, but very soluble in alcohol, ether, and wood spirit. It sublimes at 212, and at 248, is resolved into carbon, iodine, and hydriodic acid. When distilled with chloride of phosphorus, or with corrosive sublimate, it yields a peculiar liquid, of a deep red colour, and a density of 1.96, which contains chlorine, iodine, and formyl. 5707. Sulphide of formyl, C 2 H 3 S 3 (Bouchardat), is a liquid obtained by distilling one part of iodide of formyl, with three parts of sulphide of mercury. By reaction with hydrate of potash it may be converted into sul- phide of potassium and formiate of potash. Of Xylite, or Lignone. 5708. Having received from Dr. Ure a bottle of a liquid, which I under- stood to be pure wood spirit, I subjected it to the usual test of saturating it with chloride of calcium, with which wood spirit reacts eagerly, generating heat as already mentioned. I found, however, that a colourless liquid separated, and formed a supernatant stratum, in which the chloride above named did not appear to be soluble. 5709. When this liquid, and the solution of the chloride in wood spirit, were subjected to the distillatory process, by means of a boiling water bath, only the former come over, the wood spirit being retained by the chloride. 5710. It seems from the account given by Graham, 836, that the liquid which was distilled, has been examined by VViedman and Schweiger, and described under the names at the head of this section. The formula as- signed to it is C 6 H 6 O a ; which, as the admission of half atoms is incon- sistent with the grounds on which the atomic theory is built, should be doubled. 5711. The boiling point of xylit is about 142, its density 0.816. The density of its vapour to that of atmospheric air as 2177, by experiment, and 2159 by calculation. Pure xylit has an agreeable, sharp, empyreu- matic taste. It is soluble in water, and burns with a white flame. 5712. Mesiten, C 8 H 5 O 3 , agreeably to the same authority, is a liquid obtained by distilling equal parts of xylit and sulphuric acid. Chloride of calcium is utterly insoluble in mesiten, of which the boiling point is 145, and the density 0.808. 5713. Mesite is the name given to a liquid which is a concrete product of the destructive distillation of wood, which gives birth to wood spirit and 560 ORGANIC CHEMISTRY. to xylit. Being less volatile than the last mentioned product, it comes over later, and hence it may be isolated. It is formed also by the reaction of xylite with potash and potassium. 5714. Xylite Naphtha, C H 6 O 1 *, results from the reaction of hydrate of potash with mesite. It is in its properties ethereal ; being colourless, very liquid, and having the odour of peppermint. It is but slightly soluble in water, but very soluble in alcohol, in wood spirit, xylit or ether. It boils at 230, and burns with white smoky flame. 5715. Xylite oil is produced from xylit naphtha, by a renewed reac- tion with hydrate of potash. This oil has ethereal properties. 5716. Methal, C 6 H 9 , is a liquid generated by the reaction between sul- phuric acid and xylit. Pyroxanthin, by the distillation of crude wood spirit from slaked lime. These substances are more of the nature of an essential oil, or camphor, than of that of an ether. Of the Ethereal Compounds of Mesityl, or Mesitylene. 5717. The origin and characteristic properties of mesityl were stated in the general account of it, as one of the compound radicals among which it stands distinguished as being one of the few which are capable of isola- tion. As respects its properties, it may be considered as an ether, per se. 5718. Of the Chloride of Mesityl, C 6 H 5 Cl. I give precedence to this compound over the oxide, contrary to the course pursued in the other cases; as it is only by means of the former that the latter has been elaborated. To procure the chloride in question, two parts of perchloride of phosphorus are mixed gradually with one of acetone in a refrigerated vessel. On ihe addition of water to the resulting mass, an oily liquid separates, which is sufficiently heavy to sink in water, and which heat resolves into chlorohy- dric acid and mesityl. This oily liquid is the chloride of the last mentioned radical. 5719. The Oxide of Mesityl, C 6 H 5 O, is obtained by the reaction of the alcoholic solution of the chloride, above described, with caustic potash in excess ; followed by the addition of a large quantity of water, an oily liquid separates, which, being desiccated by contact with chloride of cal- cium, is afterwards distilled. Thus purified, it is a colourless liquid, having the odour of peppermint. It boils at 248, is inflammable, and burns with a brilliant flame, attended with much smoke. 5720. An impure Iodide of Mesityl has been obtained by subjecting a mixture of acetone, phosphorus, and iodine, to the distillatory process 5721. Chloride of Pteleyle. When mesityl is impregnated with chlo- rine, a sort of sub-radical is generated, C 6 H 3 , having a relation to mesityl, C 6 H 5 , analogous to that which acetyl (3093), C 4 H 3 , has to ethyl, C 4 H 5 . With the sub-radical thus generated, which was named by its discoverer, Kane, pteleyle, the chlorine combines, forming a chloride. 5722. Of the Nitrated Oxide of Pteleyle, C 6 H 3 Cl. When two parts of acetone, and one part of fuming nitric acid, are mingled, a violent reac- tion ensues. After the resulting aggregate has become cool, the addition of water causes the separation of a mixture resembling a yellow oil, which consists of two liquids. The more fluid of these has received the name of nitrite of the oxide of peteleyle. It is heavier than water, and is decomposed thereby. Paper imbued with it burns like prepared tinder. It is capable of bearing the heat of 212 without decomposition, but at a higher tempe- rature it explodes violently ; hence it cannot be distilled. 5723. Mesitic Aldehyde, C* H 3 O -f HO, or the Hydrated Oxide of OF AMYL ETHERS. 561 Pteleyle. Of the oily mixture, above described as resulting from the reac- tion of fuming nitric acid with acetone, mesitic aldehyde forms the more viscid portion. It may also be produced by subjecting a mixture of mesityl and nitric acid to ebullition as long as any reaction takes place. From the formula of this, above given, it is seen that it resembles aldehyde in being a hydrated oxide of a sub-radical, obtained from another radical by dehy- drogenation. 5724. Mesitic aldehyde is a heavy, viscid, reddish-yellow liquid, with a sweetish taste and penetrating odour. Of Amyl Ethers. 5725. It must appear from the account given of the hy- pothetical compound radical, amyl (4023), that, in certain compounds it has been inferred to play a part analogous to that which ethyl, methyl, and other bodies of like kind play in certain other compounds ; and that, especially, it has been inferred that the oxide of this radical exists in the oil of potato spirit, in union with water. This oil be- ing, therefore, a hydrated oxide of amyl, plays in the com- pounds of amyl, a part like that which alcohol performs in ethyl series, or wood spirit in the methyl series. Yet as the oxide of amyl has not been isolated, we have no amy- lic congener of ether, of which the preparation and pro- perties, in an isolated state, are to be described. Hence, the first object to be presented to the attention of the stu- dent is the hydrated oxide. Of the Hydrated Oxide of Amyl, or Oil of Potato Spirit, or Amylic Alcohol, C 10 H n O + HO. 5726. The congener of alcohol, to which the preceding name has been given, is generated during the vinous fer- mentation of an infusion of potatoes; and comes over to- wards the close of the distillation, by which potato spirit is separated from the rest of the products or residue of that process, rendering the water, which simultaneously condenses, milky. Being insoluble in this liquid, it sub- sides after some time, together with a portion of moisture and alcohol. From the latter of these impurities, it is se- parated by agitation with water, and from water by chlo- ride of calcium and redistillation. To bring over the pure hydrated oxide of amyl, a temperature of 270 is required. 5727. Potato spirit is a colourless liquid, oily in appear- ance, with a strong smell, which at first is pleasant, but becomes afterwards extremely nauseous. The inhalation 562 ORGANIC CHEMISTRY. of the vapour causes asthmatic pains, cough, and even vo- miting. Its taste is very acrid. It burns with a bluish- white flame; boils at 270; has a specific gravity of 0.8124 at 60. The density of the vapour is = 3.147, represent- ing four volumes. At 4 it solidifies, forming crystalline plates. It produces a stain on paper, which disappears after a short time; dissolves sparingly in water, to which it communicates its odour; and is rniscible in all propor- tions with alcohol, ether, fixed and volatile oils, and strong acetic acid; dissolves sulphur, phosphorus and iodine, with- out being altered by them; and may also be mixed with a solution of caustic potash, or soda, without change ; but when heated with dry potash, hydrogen is disengaged, and valerianate of potash is formed (Dumas, Stas). It absorbs a large quantity of chlorohydric acid gas, with evolution of heat. When mixed with sulphuric acid, a violet colour appears, and the bisulphate of oxide of amyl is produced.* When distilled with dry phosphoric acid, a carbohydrogen is obtained, to which Cahours has given the name of ami- lene. Amylic alcohol combines with the bichloride of tin, forming a crystalline compound, which in the air, and more rapidly when in contact with water, is slowly re- solved into its component parts, bichloride of tin, and hy- drated oxide of amyl. See valerianic acid (5283). 5728. Acetate of Oxide of Amyl, Amylo Acetic Ether, C 10 H"O, C 4 H 3 O 3 = Ayl O, Ac O 3 . It is easily obtained by distilling a mixture of two parts of acetate of potash, one of hydrated oxide of amyl, and one of oil of vitriol. The product, after being dried by means of chloride of cal- cium, and rectified along with oxide of lead, yields the acetate in a state of purity. It is a colourless liquid, having an ethereal, aromatic odour, and insoluble in water. It boils at 248. Of the Bromide and Iodide of Amyl. 5729. By distilling eight parts of bromine with fifteen parts of amylic alcohol, and one part of phosphorus, a bromide of amyl, having ethereal properties, has been obtained ; and likewise an iodide, by the same process, substituting iodine for bromine. The iodide is described as an ethereal liquid. 5730. Of Glyceryl and Cetyl, there are no ethereal com- pounds. Accordingly, I here terminate the chapter on ethers. * A congener of sulphovinic acid (5297). OF ANIMAL SUBSTANCES. 5731. Respecting the substances which come under the preceding definition, I had prepared selections from the former edition of my Compendium, and from all the other more recent sources of information within my reach, when the concluding part of the work on Organic Chemistry, by Liebig and Gregory, fell into my hands. Finding it to be sufficiently condensed, I have concluded to substitute a portion of that work for the matter which I had prepared. My only motive for publishing a text book, has been my inability to find any work comprising descriptions of my apparatus and peculiar experimental illustrations, and having the requisite arrangement and condensation. But as the portion of the work by Liebig and Gregory, to which I have alluded, is deficient neither in arrangement nor in brevity, I deem it judicious to embody it in this Compendium. 5732. As certain facts and hypotheses adduced or sanc- tioned by the philosopher of Giessen and his disciples, con- stitute the organic chemistry now in vogue, and have an important bearing on physiology, it seems expedient, so far as practicable, to allow them to be studied in that au- thentic form which they have been made to assume by Gregory, the associate editor of Liebig. Unfortunately, the organic chemistry of Liebig, as translated by Gregory, is in general too voluminous and abstruse, to serve as a chemical text book for a medical class. 5733. I shall change some names in order to produce an accordance with the nomenclature adopted in this work, and to correct an inconsistency in using the noun "nitrogen" and yet employing the adjective " azotized" Evidently either azot and azotized, or nitrogen and nitro- genized, are required by consistency.* * The reader will not be misled by some slight differences in orthography, as in fibrin and fibrine, legumen and legumine 72 564 ORGANIC CHEMISTRY. Indifferent Nitrogenized Substances common to the Vegetable and Animal Kingdoms Proteine and its Modifications. 5734. " Under this head we have to consider a few very important com- pounds, which are formed in the vegetable kingdom, and are also found to constitute a large proportion of the animal body. These are Albumen, Fi- brine, and Caseine. Till very recently, it was believed that vegetable al- bumen and fibrine differed from animal albumen, fibrine, and caseine; but the recent researches of Mulder have shown this opinion to be erroneous, and Liebig has demonstrated that caseine exists in vegetables with all the characters of that found in milk (5023). 5735. " The most important step recently made in advance in this im- portant investigation is doubtless the discovery, made by Mulder, that albu- men, fibrine, and caseine, are all modifications of one compound, to which he has given the name of Proteine (from Trganva, I take the first place), as being the original matter from which all these varieties are derived. 5736. "Proteine is composed of carbon, hydrogen, nitrogen, and oxy- gen ; and Mulder has shown, that two analyses of proteine do not differ more than analyses of fibrine, albumen, or caseine do, either from one ano- ther, or from that of proteine, as far as regards these elements. He has further shown, that all of these bodies, whether they contain proteine ready formed or not, readily yield it when acted on by alkalies. While proteine, however, contains no inorganic matter, albumen, fibrine, and ca- seine each contain small but essential quantities of mineral substances, such as sulphur, phosphorus, potash, soda, common salt, and phosphate of lime. Further, it has been established by the still more recent researches of the school of Giessen, that animal and vegetable albumen, animal and vegeta- ble fibrine, and animal and vegetable caseine, are respectively identical in every particular. We may therefore assume that there is but one albumen, one fibrine, and one caseine ; and it is convenient to consider them all as compounds of proteine with small proportions of inorganic matter (5023). 5737. "Proteine. When animal or vegetable albumen, fibrine, or ca- seine, are dissolved in a moderately strong solution of caustic potash, and the solution heated for some time to 120, the addition of acetic acid causes a gelatinous precipitate, which has the same composition and properties, from whichever of these compounds it has been prepared. When well washed and dried, this is proteine. 5738. "It forms a yellowish brittle mass, insoluble in water and alcohol. Mulder has analyzed proteine from animal and vegetable albumen, from fibrine and from cheese, or caseine; and Scherer has analyzed proteine from animal albumen and fibrine, from the crystalline lens, from hair, and from horn. The results from all these analyses agree best with the for- mula C 48 H 38 N 6 O 14 (Liebig) ; Mulder first gave the formula C 40 H 31 N 5 O 13 . The symbol of proteine is Pr. 5739. " Proteine combines with both acids and bases : with diluted sul- phuric acid it forms sulphoproteic acid, Pr + SO 3 ; with diluted chlorohy- dric acid, another acid, Pr -f- 2HC1. When chlorine is passed through a solution containing proteine, white flocks are deposited, which Mulder calls chloroproteic acid, Pr + CIO 3 . (Mulder.) 5740. "When proteine, or any of its modifications, is digested in nitric acid, a yellow compound is formed, along with oxalic acid and ammonia. The yellow compound is called xanthoproteic acid, and its formula is C 34 OP ANIMAL SUBSTANCES. 565 H 34 N 4 O 13 , 2HO. It seems to combine both with acids and bases. Its salts with bases dissolve with a red colour. (Mulder.) 5741. "When boiled with an excess of caustic potash, proteine, albumen, &c., are decomposed, yielding, besides ammonia and carbonic and formic acids, three azotized products, protide, erythroprotide, and leucine. Ery- throprotide is a reddish-brown amorphous mass; and its formula, in the compound it forms with oxide of lead, is said to be C 13 H 8 NO 5 . Protide is a yellowish, soluble, uncrystallizable substance, and its formula is C 13 Ei 9 NO 4 . Leucine crystallizes in shining scales, which sublime unaltered at 338. Its formula is C 13 H 13 NO 4 . With one atom of hydrated nitric acid it yields nitroleucic acid, which forms crystallizable salts. Leucine may also be formed by the action of sulphuric acid on proteine or its com- pounds. (Mulder.) 5742. "According to Mulder, proteine combines with the oxides of lead and silver in the proportion of ten atoms to one of the base : and the same amount of proteine is contained in albumen and fibrine; the former being lOPr + S 3 + P, the latter lOPr + S 4 + P. 5743. "According to Liebig, (Animal Chemistry, p. 106,) proteine is produced by vegetables alone, and cannot be formed by animals ; although the animal organism possesses the power of converting one modification of proteine into another, fibrine into albumen, or vice versa, or both into ca- seine, &c. In this point of view the vegetable forms of proteine, vegetable albumen, fibrine, and caseine, become signally important, as the only sources of proteine for animal life, and consequently of nutrition strictly so called, that is, the growth in mass of the animal body. 5744. " Proteine is never found, as such, in nature; but occurs in the shape of albumen, fibrine, or caseine, both in vegetables and animals, and in some other forms in the animal body. Modifications of Proteine. 5745. " Albumen. This important substance forms the white of eggs, and occurs in large quantity in the blood. It is also found in other animal fluids, and in most of the animal solids. 5746. "It occurs also in many vegetable juices, and in many seeds, such as nuts, almonds, &c. From whatever source it is obtained, its properties are the same. 5747. "Albumen is naturally soluble in water, and is found dissolved in the serum of the blood, and in vegetable juices. The white of eggs is quite soluble ; and the albumen of wheat flour also dissolves in water, if it have been purified without the application of heat. But when it has once been heated to 160, it becomes insoluble; and, if previously dissolved, a heat of 158 causes the dissolved albumen to coagulate, and the coagulum is inso- luble in water. Hence albumen is described in two states, the soluble and the coagulated. 5748. "If white of egg, or serum of blood, be dried up at 120, the resi- due is soluble albumen in an impure state. It may be purified by being well washed with cold ether and alcohol, which remove fat, salts, and other foreign matters. 5749. "Dry soluble albumen, when placed in water, first swells up, and then forms a glairy fluid. This solution is coagulated by heat, by acids, by alcohol, by creosote, &c. The acids which do not coagulate albumen are acetic acid, phosphoric and pyrophosphoric acids. The coagulated al- 566 OP ORGANIC CHEMISTRY. bumen dissolves, with the aid of heat, in strong hydrochloric acid, pro- ducing a purple solution. This reaction takes place with all the modifica- tions of proteine, and indicates a great similarity of constitution among them. 5750. "The solution of albumen is also coagulated or precipitated by the acetate of lead and the bichloride of mercury, and by infusion of galls ; also by the ferrocyanide of potassium if acetic acid be added. From the insolu- bility of the precipitate with bichloride of mercury, white of egg, beat up with water, is used as an antidote to that poison. One egg combines with about four grains of corrosive sublimate. 5751. "The precipitates formed by acids are compounds of albumen with the acid employed. They are soluble in pure water, but quite insolu- ble in diluted acids. 5752. " Coagulated albumen is quite insoluble in water, but is readily dissolved by caustic alkalies, which it even neutralizes. These compounds yield insoluble albuminates with the metallic salts. 5753. "Coagulated albumen, when acted on by hydrochloric acid, yields from one to two per cent, of phosphate of lime; and soluble albumen ap- pears to possess the property of dissolving that salt, a property which ena- bles the blood to convey to the bones their earthy part, and probably also to carry away that which is found in the urine. 5754. " When albumen is analyzed, it yields the same results as pro- teine, in regard to carbon, hydrogen, nitrogen, and oxygen; but it contains less than one per cent, of sulphur and phosphorus together, which are ab- sent in proteine. According to Mulder, it is lOPr -}- S 3 + P ; but we have no means of determining with accuracy such small proportions of sulphur and phosphorus, and it is therefore preferable to represent albumen as pro- teine with certain small indeterminate proportions of sulphur and phos- phorus. When burned, it also leaves ashes, which contain phosphate of lime and alkaline salts. 5755. "To prove the presence of unoxidized sulphur in albumen, dis- solve it in potash, then add acetate of lead as long as the precipitate formed is redissolved, and heat the solution to the boiling point. It instantly be- comes black by the separation of sulphuret (sulphide) of lead. The same test applies to fibrine and caseine. (Liebig.) It is not known in what state the phosphorus exists in albumen, after phosphate of lime has been sepa- rated. The fetid smell of putrefying albumen, indicates distinctly the pre- sence of sulphuretted hydrogen (sulphydric acid) among the products of its putrefaction. 5756. " When the juice of many vegetables, after being separated from the coagulum or deposit which spontaneously forms in it, and which is vegetable fibrine, is heated, a new coagulum is formed, which is vegetable albumen. When nuts, almonds, and similar seeds, are freed from their oil by pressure, the residue is chiefly vegetable albumen in the soluble form. It is, in every respect, identical with the albumen of eggs and of blood. 5757. " Albumen must be considered as the true starting point of all the animal tissues. This appears from the phenomena of incubation, where all the tissues are derived from the albumen of the white and of the yolk, which contains albumen also, with the aid only of the air, of the oily matter of the yolk, and of a certain proportion of iron, also found in the yolk. It is clear from this, that albumen may pass into fibrine, caseine, membranes, horn, hair, feathers, &c. OF ANIMAL SUBSTANCES. 567 5758. " Fibrine. This modification of proteine occurs, like albumen, in two forms, dissolved and coagulated. The former is found in fresh-drawn blood and in fresh-drawn vegetable juices, from both of which it coagulates spontaneously on standing. In the coagulated state it is found in muscular fibre, and in the gluten of wheat flour and the seeds of the cerealia gene- rally. 5759. " The characters of insoluble or coagulated fibrine closely resem- ble those of coagulated albumen. With strong acetic acid it forms a jelly, which may be dissolved by boiling water, and is precipitated by ferrocyan- ide of potassium. It is similarly acted on by other acids; and, like albu- men, dissolves in alkalies, which it neutralizes. It gives a purple solution with strong hydrochloric acid. 5760. "When fresh blood is allowed to stand, the fibrine dissolved in it coagulates very soon, and forms the clot, which, however, is coloured by the globules of the blood ; but if the blood be stirred with a stick while co- agulating, the fibrine adheres to the stick in grey stringy masses, which dry, like albumen, into a horny matter. Like albumen, it contains sulphur and phosphorus, and its ashes contain phosphate of lime. It contains less sulphur, however, than albumen.* 5761. "As albumen, during incubation, passes into fibrine, so fibrine, in the animal body, passes into albumen ; for example, in the case of an ani- mal fed on muscular fibre, whose blood contains the usual proportion of al- bumen. Nay, Denis has shown that the fibrine of venous blood, by diges- tion with a solution of nitre, is dissolved, and acquires the characters of albumen, being coagulated by heat and by acids. Scherer has shown that the fibrine of arterial blood does not undergo this change, nor that of the buffy coat, nor even venous fibrine after exposure to the air for some time. Hence he concludes that it is rendered incapable of dissolving by the action of oxygen, and that the fibrine of venous and of arterial blood are thus dis- tinct; the former being soluble, the latter coagulated. 5762. " He found that the above mentioned solution of venous fibrine in nitre, when exposed to the air, deposited an insoluble matter, identical with arterial fibrine. He also observed, that, after being boiled for a short time, venous fibrine became insoluble, and had lost the property, possessed by it when fresh, of absorbing oxygen and giving off carbonic acid. 5763. " The fibrine which spontaneously coagulates from certain vege- table juices, such as those of carrots, turnips, and beet-root, and that con- tained in the gluten of wheat flour, are identical in properties and composi- tion with animal fibrine. 5764. " Fibrine, both animal and vegetable, is a most important element of nutrition, and yields, in the animal body, albumen, caseine, and the tis- sues derived from them. 5765. " Caseine. This, the third important modification of proteine, is found in milk, and constitutes that ingredient which is neither coagulated spontaneously, like fibrine; nor by heat, like albumen; but by the action * To determine the quantity of fibrine in blood, M. Simon receives it in a flask containing little bits of metal first weighed without the flask, then with this reci- pient ; and after the introduction of the blood, the flask and its contents are weighed together. On agitating the flask, the bits of metal become coated with fibrine. Sub- sequently they are washed with water, dried, and weighed. By these means, guard- ing against any deficit, the weight of the fibrine may be deduced. Agreeably to the same authority, menstrual blood contains no fibrine." Berzelius' Report 1841 page 263. 568 ORGANIC CHEMISTRY. of acids alone. Cheese, made from skimmed milk and well pressed, is nearly pure caseine. A substance quite identical is found abundantly in the seeds of leguminous plants, and was formerly called Legumine. Liebig has recently shown that legumine is nothing but caseine; and, from what- ever source, it is found to be a compound of proteine. Thus its analysis gives the same results as those of fibrine and albumen for the four organic elements ; and it differs from these bodies in containing no free phosphorus. Its ashes are very rich in phosphate of lime and in potash ; and in this point also animal and vegetable caseine agree. 5766. " Coagulated caseine is generally a compound of caseine with the acid employed to coagulate it. When milk, on standing long, coagulates, it is found to contain free lactic acid, some of which by combining with the caseine has caused the precipitate. When sulphuric acid is used, the coa- gulum is sulphate of caseine ; which, when the acid is removed by carbon- ate of lead, yields pure caseine. 5767. " When dry, caseine thus prepared is like gum. It is not readily dissolved by water, and never forms a clear solution. It is precipitated by acetic acid, but in other respects resembles a solution of albumen, except that it is not coagulated by heat. When milk is placed in contact with rennet^ which is the lining membrane of a calf's stomach, it is coagulated. Liebig has shown, that, unless the membrane be in a state of decomposition, this change does not take place ; and it probably depends on the formation, under the fermenting influence of the membrane, of sufficient lactic acid to neu- tralise the alkali of the milk, and thus coagulate the caseine. When sweet milk or cream is used, the cheese contains much butter besides the caseine. 5768. " When milk is heated in an open vessel, a pellicle is formed, which, if removed, is continually renewed, and is insoluble. It is owing to the action of oxygen, for it does not form in an atmosphere of carbonic acid. (Scherer.) 5769. " When peas, beans, or lentils are softened in cold water, then ground with that fluid, and the mass further diluted, and strained through a fine sieve, there passes through a solution of caseine in which starch is suspended. When the starch has settled, the supernatant liquid is a solu- tion of caseine, which is always, like milk, turbid, partly from suspended fat, partly from the gradual action of the air on the dissolved caseine, lactic acid being slowly formed, which causes a gradual separation. 5770. " This solution has all the characters of skimmed milk ; it is coagu- lated by acids, not by heat, and forms a pellicle when heated. It also co- agulates after long standing from the formation of lactic acid ; and, when the coagulum putrefies, the odour is exactly that of putrid cheese. (Liebig.) 5771. "The ashes of soluble caseine, whether animal or vegetable, are very strongly alkaline ; and there is reason to believe that the potash found in the ashes had served, by combining with the caseine, to render it soluble. 5772. " Caseine occurs also in the oily seeds, such as almonds, nuts, &c. along with albumen, and must be considered as a very important element of nutrition. 5773. " Scherer, by acting on the serum of blood with water and a little caustic potash, obtained a neutral solution, which no longer coagulated by heat, but formed a pellicle like milk. As this pellicle appeared identical with that from milk, the experiment seems to prove the conversion of albu- men into caseine. 5774. "Mulder considers caseine to be lOPr-fS; but pure caseine is OF ANIMAL SUBSTANCES. 569 not known, and caseine, as it usually occurs, contains 6.5 per cent, of in- organic matter, chiefly phosphate of lime and potash. There is no doubt, however, that the organic elements of caseine are united in the same pro- portion as those of proteine, albumen, and fibrine ; while, like the two latter, it yields a purple solution when heated with strong chlorohydric acid. The action of milk, also, in the nutrition of young animals proves that caseine is capable of conversion into albumen and fibrine ; while the production of milk in an animal fed on albumen or fibrine, or both, shows that these bo- dies may be reconverted into caseine. 5775! We may exhibit the connection between these substances as follows. Pr represents proteine, C 48 H 38 N 6 O 14 . P and S represent, not equivalents, but only small indeterminate quantities, of phosphorus and sulphur. Albumen is . Pr-f S a +P-f- salts. Fibrine is . Pr+S +P-f salts. Caseine is . Pr-j-S -f salts. 5776. " We can thus easily understand the formation of any one of them from proteine, or the conversion of one into the other. Albumen, losing half its sulphur, becomes fibrine; and fibrine, losing its phosphorus, be- comes caseine : but the salts are not exactly the same, nor in the same pro- portions in all the three cases. The Blood,. 5777. " This important fluid, from which alt parts of the body are form- ed, possesses very remarkable properties. In the veins it is dark-coloured, in the arteries bright red. When drawn, it presently forms a red clot, composed, as we have seen, partly of fibrine, while the serum contains a large quantity of albumen. 5778. " The colour of the clot is owing to a compound which has. been called Hcematosine, which has many properties in common with albumen ; but the globules of the blood, in which the colour naturally resides, are not composed of hsematosine alone, but contain another albuminous compound, to which the name of (rlobuline has been given. It is probable that neither of these compounds is known in a state of purity. 5779. " To obtain them, blood is well stirred to separate the fibrine, and mixed with six volumes of a saturated solution of sulphate of soda, in which the globules are insoluble. They are then boiled with alcohol acidulated with sulphuric acid, which dissolves a sulphate of hsematosine, and leaves a sulphate of globuline. The red alcoholic solution is mixed with carbonate of ammonia, which separates the sulphuric acid as sulphate of ammonia, along with a little globuline. The filtered solution, being evaporated, leaves hsematosine as a dark brownish red mass. 5780. " Hsematosine thus prepared is insoluble in water, alcohol, and ether, but forms red solutions with alcohol, to which either acids or alkalies are added. Its ashes contain iron, but Liebig and Scherer have shown that the red colour does not depend on that metal, which may be removed either from the globules, or from ha3matosine, by strong sulphuric acid, without destroying the red colour; and in this experiment the red matter left gives a white ash, free from iron. Iron, however, is essential to the blood, and is consequently supplied in the food. The ashes of almost all vegetables con- tain a little iron; flesh, of course, does so, as it is mixed with blood; and the yolk of egg is found to contain an oily matter, of which iron is an in- gredient. 570 OF ORGANIC CHEMISTRY. 5781. " Globuline forms the principal part of the blood-globules. It has not been obtained in a pure state, but has all the characters, as well as the composition, of dissolved albumen. The compound with sulphuric acid above mentioned, is grey, or white, and was found to contain four atoms of sulphuric acid and one of proteine. 5782. "Besides albumen, the serum of the blood contains fat and saline matters. When heated, the albumen coagulates, and floats in a watery liquid called the Serosity. This contains common salt, sulphates, phos- phates, and carbonates. The blood probably also contains the ingredients of the secretions and excretions, such as bile and urine; but these are in so small a proportion, that, except in cases of disease, it is hardly possible to detect them. The fatty matter in blood is obtained by drying up the serum and digesting with ether. It consists of the usual animal fats, and is said likewise to contain cholesterine, or the fat of bile. 5783. " The following table gives the results of two careful analyses of blood by Lecanu : Human blood. Water 780.145 785.590 Fibrine . 2.100 3.565 Colouring matter (haematosine and globuline) - - 133.000 119.626 Albumen - . 65-090 69.415 Crystalline fat - - 2.430 4.300 Oily matter - . 1.310 2.270 Extractive matter (soluble in water and alcohol) - 1.790 1.920 Albuminate of soda - - - 1.265 2.010 Alkaline chlorides, carbonates, phosphates, and sulphates 8.370 7.304 Carbonates of lime and magnesia, phosphates of lime, > i no 1 414 magnesia, and iron, peroxide of iron Loss - - - 2.400 2.586 1000.000 1000.000 5784. " It is obvious, that, as the blood is chiefly composed of compounds of proteine, its composition cannot be very different from that of proteine or its modifications. In fact, dried blood, when analyzed, yields the formula C 48 H 39 N 6 O 15 , which is proteine, C H 36 N 6 O 14 + HO + H a . (Playfair and Boeckmann.) This excess of hydrogen is probably derived from the presence of fat. 5785. " From the blood, that is, from the compounds of proteine in the blood, are derived all the animal tissues. Some of these are compounds of proteine, others have no longer the characters of such compounds ; but in all cases they are derived from proteine. 5786. " Muscular tissue, or muscular fibre, is composed chiefly of fibrine, mixed however in the ordinary state with blood, membranes, ner- vous matter, and fat. Dried flesh, when analyzed, gave the same formula as dried blood, namely, C 48 H 39 N 6 O 15 . (Playfair and Boeckmann.) 5787. " When flesh is acted on by hot water, there is dissolved a quan- tity equal to 17 per cent, of its weight. The dissolved matter contains the salts of flesh, and several organic matters probably produced in the opera- tion, the nature of which is very little known. One of these has been de- scribed unde.r the name of Osmazome, and is supposed to give to soup and dressed meat their peculiar flavour : but osmazome is certainly not a pure substance, as at present known ;* and the whole subject of the changes * In other words, osmazome is not a definite compound to which any formula can be assigned, but probably a mixture of substances not yet distinguished. OF ANIMAL SUBSTANCES. 571 produced in food by cooking is understood to be under investigation by Liebig. 5788. " Gelatinous tissue. Under this name are included the organic tissue of the bones, that of tendons and ligaments, the cellular tissue, the skin, and the serous membranes. All these substances dissolve by long- continued boiling in water, and the solution on cooling forms a jelly. The coarser forms of gelatine, from hoofs, hides, &c. are called Glue; that from skin and finer membranes is known as Size; and the purest gelatine, from the air-bladders and other membranes offish, is called Isinglass. Gelatine does not exist as such in the animal tissues, but is formed by the action of boiling water.* 5789. " Gelatine is soluble in water, and the hot concentrated solution forms a jelly on cooling. It is precipitated by tannic acid, forming an inso- luble compound, which forms the chief part of leather. Leather is made by steeping softened skins in a strong infusion of oak-bark, catechu, or other astringent vegetables containing tannic acid. Skins are prepared in other ways, yielding different kinds of leather, such as tawed leather, wash- leather, &c.; but the process of tanning depends on the action of tannic acid on the gelatinous tissue. 5790. " Gelatine, when acted on by sulphuric acid, yields gelatine su- gar, or glycicoll, C 8 H 7 N 3 O 5 , 2HO. When treated with potash, it is said to yield glycicoll and leucine. Glycicoll unites with oxide of lead, forming a compound, C 8 H 7 N 3 O 5 , 2PbO. (Mulder.) It also combines with nitric acid, forming a compound acid, C 8 H 7 N 3 O 5 -f 2NO 5 -f 4HO, which crystallizes, and forms double salts with bases. That with lime is CaO,C 8 H 7 N 3 O + 2(CaO, NO 5 ). 5791. "According to Scherer, the composition of gelatinous tissue is represented by the formula C 48 H 41 N 7 O 18 , or doubled, C 96 H 83 N 15 O 38 ; which latter formula represents 2 atoms proteine -f- 3NH 3 , -f-HO -f O 7 . 5792. " Although gelatine is thus nearly related to proteine, and is doubt- less formed from one or other of its modifications, yet it has none of the characters of a compound of proteine. It does not yield proteine when acted on by potash, and it does not produce a purple colour with hydrochlo- ric acid. It therefore no longer contains proteine. 5793. " This accounts for the fact, that animals, fed exclusively on gela- tine, die with the symptoms of starvation. The gelatine, containing no proteine, cannot yield albumen, fibrine, or caseine; and it has already been stated that the animal system, although it can convert one form of proteine into another, cannot form proteine from compounds which do not contain it. Blood therefore cannot be made from gelatine, and the animal soon dies. But when mixed with other food, especially compounds of proteine, gelatine may be useful, and may serve directly to nourish the gelatinous tissues. (Liebig, Animal Chemistry, 98, 130.) This would explain the use of gelatine as a part of the food of convalescents, whose debilitated sys- tem cannot readily convert albumen, &c. into gelatine for the nutrition of these tissues, and finds it ready-made in the food. The experiments of D'Arcet on the gelatine from bones have proved, that, as part of the diet in hospitals, gelatine produces the best effects, and materially abridges the * How happens it then, that, as it exists in the hides or skins of animals, it com- bines with tannic acid to form a substance (leather), precisely the same in its che- mical composition as the precipitate formed by a solution of gelatine with that acid ? 73 572 ORGANIC CHEMISTRY. period of convalescence. When it is given alone, all animals soon refuse it with disgust, and die if confined to gelatinous food. 5794. " Chondrine. This substance forms the tissue of cartilage as it occurs in the ribs, trachea, nose, &c. and of the cornea. It is slowly dis- solved by boiling with water, and when dry resembles glue. But it differs from gelatine in not being precipitated by tannic acid, and in giving pre- cipitates with acetic acid, alum, green vitriol, and acetate of lead. Bones, when in the cartilaginous state, are composed of it. According to Scherer, it is composed of C 48 H 40 N 6 O 30 ; that is, of proteine + 4HO + O 3 . Chondrine leaves, when burned, from 4 to 6 per cent, of ashes, chiefly bone-earth. 5795. " Arterial Membrane. The middle coat of the artery, which is a very elastic membrane, leaves, when burned, 1.7 per cent of ashes. According to Scherer, it is composed of C 48 H 38 N 8 O 16 ; that is, proteine + 2HO. 5796. "Horny matter. This occurs in two forms, membranous and compact. The former constitutes the epidermis, and the epithelium, or the lining membrane of the vessels, of the intestines, and of the pulmonary cells. The latter forms hair, horn, nails, &c. 5797. " Scherer has analyzed numerous specimens of both kinds of horny matter, and deduces from his results the formula C 48 H 39 N 7 O 17 ; that is, proteine + NH 3 -f O 3 . 5798. " Horny matter, when acted on by potash, yields proteine on the addition of acetic acid. 5799. " Feathers are closely allied to horny matters, but, according to Scherer, contain one atom of oxygen less ; the formula of feathers, deduced from his analysis, being C 48 H 39 N 7 O 16 . 5800. " Pigmentum nigrum oculi. This substance, according to Scherer, contains more carbon than any of the preceding ; but its formula has not been ascertained. 5801. " It is to be particularly observed, that the formula above given for the principal tissues of the body, are only intended to show the relation they actually bear to proteine. It is not meant that they are formed in the body by the addition of water, ammonia, or oxygen, to proteine : on the contrary, we are as yet ignorant of the conditions under which they are produced; and in some cases, as, for example, in gelatine, several different views may be taken of their formation. Brain and Nervous Matter. 5802. " Nervous matter is distinct from all other animal tissues, and is produced by the animal system exclusively. In composition it is interme- diate between fat and the compounds of proteine, containing nitrogen, which is absent in fats, but in far smaller quantity than proteine does; and being, on the other hand, much richer in carbon than proteine or its compounds. It appears likewise to contain phosphorus as an essential ingredient. 5803. " From the recent researches of Fremy, brain appears to contain a peculiar acid, analogous to the fatty acids, which he calls cerebric acid, and which contains nitrogen and phosphorus; this is mixed with an albu- minous substance, with an oily acid the oleophosphoric acid, with choles- terine, and finally with small quantities of oleine and margarine, and of oleic and margaric acids. 5804. " The two acids peculiar to the brain and nervous matter, occur OF ANIMAL SUBSTANCES. 573 sometimes free, but generally combined with soda or with phosphate of lime. 5805. " Cerebric acid is extracted by ether from the brain after it has been exposed to the action of boiling alcohol, which coagulates the albumen. The matter deposited on cooling by the ether is a mixture of cerebric acid, generally combined with soda or bone-earth, oleophosphate of soda, and a little albumen. 5806. " This mixture is acted on by alcohol, acidulated with sulphuric acid, which precipitates sulphates of lime and soda, and albumen. The fil- tered solution contains cerebric and oleophosphoric acids; cold ether re- moves the latter, and the former is purified by solution in hot ether and crystallization. 5807. " When pure, it is white, crystalline, and pulverizable. In hot water it swells up like starch, but does not dissolve. It contains phos- phorus, but no sulphur if purified from albumen ; the phosphorus amounts to barely one per cent. ; and it contains 2.3 per cent, of nitrogen. It has the characters of a fatty acid, but its acid properties are feebly marked. 5808. "Oleophosphoric acid. This acid has not yet been obtained quite pure. With the alkalies it forms soaps, and its compound with soda ap- pears to exist in the brain. When it is long boiled with water or alcohol, it is resolved into oleine and phosphoric acid. This change is accelerated by acids, but it takes place also spontaneously at the ordinary temperature, only more slowly ; and the presence of animal matter in a state of decom- position seems to cause it to be resolved into oleine and phosphoric acid. Thus, when brain has been allowed to undergo partial putrefaction, it no longer yields oleophosphoric acid, but oleine and phosphoric acid. It con- tains two per cent, of phosphorus. The oleine of this acid is identical with that of human fat. 5809. " Cholesterine. This fat, as extracted from the brain, in which it occurs in considerable quantity, has the same composition and properties as the fat of biliary calculi. (Couerbe; Fremy.) Fremy has also suc- ceeded in detecting in the liver, traces of the characteristic fat acids of the brain. 5810. " The grey portions of the brain appear to be chiefly albuminous; while the white portions consist of an albuminous tissue similar to the grey, but loaded with the fats above described. 5811. " The softening of the brain in diseases of that organ seems to be the result of putrefaction, and is accompanied by the separation of the oleine from the phosphoric acid. The oleine itself also is decomposed, yielding free oleic acid. 5812. "There can be no doubt that the brain and nervous matter (which is quite similar to brain) are formed in the body from compounds of pro- teine, either by the loss of some azotized compounds, or by the addition of highly carbonized products, such as fat. But we are ignorant in what part of the body, or by what organs, nervous matter is prepared. This point requires minute investigation. In the mean time, according to Chevreul, the fatty matters, which occur in small quantity in the blood, are similar to those of the brain. 5813. "Bones. The bones of animals are composed of bone-earth and gelatinous tissue. By the action of hydrochloric acid, the earthy matter is dissolved, and the animal tissue is left. It is soft, retains the form of the bone, and, when dried, becomes brittle and semitransparent. When boiled 574 ORGANIC CHEMISTRY. with water, it yields a solution of gelatine, fatty matter remaining undis- solved. 5814. " Tljeaearthy matter is formed of a peculiar phosphate of lime, 8CaO + 3P 3 0*= HO, 2CaO, P 2 O 5 -f 2(3CaO, P 2 O); that is, a com- pound of two forms of tribasic phosphate. It forms rather more than half the weight of the bone, and contains a variable proportion of carbonate of lime. Fluoride of calcium is sometimes, but not always, present in recent bones; in fossil bones, and in human bones from Herculaneum, it is always found. 5815. "Teeth contain the same ingredients as bones, but the proportion of earthy matter is greater, amounting to nearly seventy per cent. The enamel of the teeth contains no animal matter, and fluoride of calcium is found in it. 5816. "In rickets, the proportion of earthy matter is much diminished. Callus and exostosis are said by Valentin to contain more carbonate of lime than sound bone, and carious bone to contain less. 5817. "When bones are heated in the open fire, they leave an earthy skeleton, which is quite white, and has the form of the bone. If bones are heated in close vessels, they give off carbonate of ammonia and tarry pro- ducts, and leave a black mass, which consists of bone-earth, with about ten per cent, of finely divided charcoal. It is called bone or ivory-black, and is much used to decolorize organic solutions. Animal Secretions and Excretions. 5818. "Milk. This important secretion, destined for the support of the young of the mammalia, is characterized by the caseine it contains. But it also contains certain oily or fatty matters which constitute butter, and which, besides fats analogous to the ordinary animal fats, contain certain volatile acids (5052, 5056), to which the smell and peculiar taste of butter are owing. Milk further contains sugar of milk, or lactine (4070) ; and, when the caseine has been coagulated by an acid, the whey, besides lactine and salts, contains an albuminous matter, which is coagulated by heat. 5819. " The composition of milk is such, that it is capable of supporting animal life without any other food. Its caseine and albumen serve for the formation of blood, and for the nutrition of the animal tissues, while its su- gar and fat support respiration ; and it furnishes, besides, all the salts which the body requires. 5820. " The following table exhibits the composition of the milk of wo- man, of the ass, and of the cow. (Henry and Chevallier.) Milk of Woman. Ass. Cow. Cheese or caseine - - 1.52 1.82 4.48 Butter .... 3.55 0.11 3.13 Sugar of milk - 6.50 6.08 4.77 Salts and mucus - - - 0.45 0.34 0.60 Water .... 87.98 91.65 87.02 100.00 100.00 100.00 5821. " When the food is highly farinaceous, the proportion of butter is increased ; but when the food contains much of the compounds of proteine, there is less butter and more caseine present. The more active exercise is taken, the smaller also is the proportion of butter. OP ANIMAL SUBSTANCES. 575 5822. " Milk, after it has become sour, undergoes the vinous fermenta- tion (5215). 5823. " Saliva. This fluid, secreted by the salivary glands, is com- posed of water, with about one per cent, of solid matter, partly saline. It often contains a trace of sulphocyanide of potassium, or at least of a salt which strikes a red colour with persalts of iron ; but this might be done by an acetate. The animal matter of saliva has been described under the name of Salivary matter. It is soluble in water, and not coagulated by heat. 5824. " Saliva possesses, in an eminent degree, the property of frothing with air, like a solution of soap; and Liebig (Animal Chemistry, p. 113) conceives that its use is to introduce in this manner, during mastication, a certain quantity of air into the stomach, the oxygen of which is employed in digestion.* * As I find that Berzelius, Graham, and Kane, give more importance to pepsine than is accorded by Liebig and Gregory, I deem it expedient to subjoin the follow- :ount of it, prepared by me recently, from Berzelius' Report, 1840, ing abridged account of it, preparei 322, and Graham's Elements, 1030. Pepsine. The name of pepsine has been given to a peculiar matter constituting the active principle of the gastric fluid, the discovery of which is due to Mr. Wasmann. Pep- sine may be obtained by infusing the mucous membrane of the stomach in acidu- lated water. The solution thus procured, has the property of dissolving the coagu- lated white of egg completely in half an hour. When the membrane, without being cut into pieces, but well washed, is digested in a large quantity of water, at a temperature between 86 and 98, a variety of sub- stances are extracted as well as pepsine ; but if afterwards cold water be substituted for the warm, scarcely any matter besides pepsine is taken up. The extraction may endure with successive portions of water, until symptoms of putrefaction ensue. The solution thus obtained, with the addition of a little chlorohydric acid, has the property of dissolving coagulated albumen speedily. Pepsine, extracted by these means, contains a little albumen, which may be precipitated by ferrocyanide of po- tassium, or by heating the solution, if not too dilute, to a temperature between 170 and 212 without ebullition. By these means the coagulated albumen is precipitated in flocks, with a little modified caseine. Pepsine may be precipitated from its solutions by the protosulphate of iron, sul- phate of copper, acetate of lead, or protochloride of tin. From the precipitates thus made, it may be separated by exposure, while suspended in water, to sulphydric acid. In precipitating, pepsine retains a sufficient portion of the acid of the saline pre- cipitant to have a decided reaction with litmus, and is highly endowed with its ap- propriate solvent powers. Acetate of pepsine may be procured by decomposing, by sulphydric acid, the pre- cipitate made as above suggested, by acetate of lead, evaporating the residual solu- tion to the consistence of syrup, and subjecting it to alcohol. The acetate separates in white flocks, which, by desiccation, acquire the appearance of a gum, and are readily soluble in water. Of pepsine in this form, one part in 60,000 parts of water, with a minute addition of chlorohydric acid, dissolves indurated albumen within about six or eight hours. A similar efficacy is ascribed to the chlorohydrate of pepsine, which may be ob- tained by precipitating the solution by bichloride of mercury, and subjecting the pre- cipitate to the process above described in case of the acetate. Mr. Wasmann has remarked, that the pepsine obtained from the pig is devoid of the power to coagulate milk, although that of the calf is highly endowed with this power. Agreeably to some comparative trials of the solvent powers of dilute chlorohydric acid, without pepsine, and one other portion of the same acid containing this princi- ple, it appeared that the one was endowed with all the solvent powers of the gastric fluid in a high degree, at ordinary temperatures, while the other, under like circum- stances, displayed them only to an insignificant extent; but when the acid, without pepsine, was aided by boiling heat, its solvent powers were equal to that of the solu- tion of pepsine. 576 ORGANIC CHEMISTRY. 5825. " Gastric Juice. This remarkable fluid seems to contain hardly any principle capable of accounting for its solvent power. In the empty stomach it is neutral, but during digestion it becomes acid, from the sepa- ration of free muriatic acid. According to Wasmann and other chemists, it contains a peculiar principle, Pepsine, which has the property of dissolv- ing food, and which is obtained by the action of water on the well-washed lining membrane of the stomach of the pig. According to Liebig, however, pepsine, as a distinct compound, does not exist. The solution of the lining membrane, slightly acidulated with chlorohydric acid, certainly dissolves albumen and fibrine, if kept in contact with them out of the body at the ordinary temperature. But none of these effects take place, unless the membrane has been previously exposed to the air, and is in a state of de- composition. Hence Liebig ascribes (Animal Chemistry, 109 seq.) the solvent power of the gastric juice to the gradual decomposition of a matter dissolved from the membrane, aided by the oxygen introduced in the saliva. Albumen, &c. when thus in contact with decomposing or fermenting mat- ter, are rendered soluble by a new arrangement of their particles. The accumulation of free chlorohydric acid, derived, no doubt, from common salt, at last puts a stop to further change. The whole food is now brought into the form of chyme, an opaque homogeneous fluid, which afterwards passes, first into chyle, and finally into perfect blood. In the chyle, the formation of fibrine has already taken place ; for, when drawn, it coagu- lates spontaneously, like blood.* 5826. " Pancreatic Juice. The fluid secreted by the pancreas is pour- ed into the duodenum, and mixes with the chyme as the latter leaves the stomach. It contains albumen, and, according to some, caseine, and is acid. Its nature, however, is little understood, and its uses at present are unknown. Bile and Biliary Calculi. 5827. " The bile is a yellowish green viscid liquid, secreted by the liver. It has a faint disagreeable smell ; and its taste is at first sweet, afterwards bitter and nauseous. Ox bile has been chiefly examined, but that of man and other animals is very similar. The researches of Tiedemann and Gmelin, of Berzelius and Demarcay, have shown that bile may be made to yield a vast number of different compounds, most of which are products of decomposition. 5828. " The bile, according to Demar9ay, contains soda in combination with a peculiar acid, choleic acid. When bile is boiled with an excess of chlorohydric acid, it yields ammonia, taurine, and choloidic acid; and, when boiled with caustic potash, it yields carbonic acid, ammonia, and cholic acid. 5829. " Choleic Acid. When bile is acted on by alcohol, certain im- purities are left undissolved. The purified bile gives with acetate of lead a * Chyle resembles blood in resolving itself into a coagulum, and a liquid like se- rum, which, according to Dr. Prout, consists partly of albumen, but principally of incipient albumen. The coagulum, according to Vauquelin, is imperfect fibrin ; but Brande considers it as more allied to caseous matter. The opinions of Prout and Vauquelin derive support from the consideration that, as chyle is destined to become blood, it may be reasonably expected to contain the principal constituents of that liquid, in a state advancing towards maturity. These inferences respecting chyle, made in the former edition of this Compendium, appear to be sanctioned by those of Liebig expressed in the text. OP ANIMAL SUBSTANCES. 577 precipitate of choleate of lead, which, when acted on by sulphuretted hy- drogen, yields choleic acid. 5830. " It forms a yellow spongy mass, soluble in water and alcohol, which has an acid reaction and a bitter taste, and is decomposed by heat. It combines with soda, forming a compound which Dema^ay considers as a soap, the solution of which in water has the physical characters of bile. But although this be the case, and although the composition of the choleic acid appears to be the same as that of the organic part of bile, yet we can- not consider the bile as choleate of soda ; for the latter is decomposed by acetic acid, which has no action on bile. .5831. " According to the analyses of Demarcay and Dumas, as calcu- lated by Liebig, the formula of choleic acid is C 76 H 66 N a O 3 , and this for- mula may represent also the organic part of the bile. 5832. " When choleic acid is boiled with chlorohydric acid, it yields ammonia, taurine, and choleidic acid. The latter, being insoluble, is de- posited, and the taurine is extracted from the mother liquor by concen- trating and adding a large quantity of alcohol, when the taurine slowly crystallizes. 5833. " Choloidic Acid. This acid is solid, fusible, of a yellow colour and bitter taste, insoluble in water, soluble in alcohol. It combines with bases, neutralizing them, and forming salts which are soluble in alcohol. It contains no nitrogen, and its formula is C 73 H 56 O 13 . 5834. " Taurine. This substance forms white crystalline needles, which are soluble in water, and sparingly soluble in alcohol. Its formula is C 4 H 7 NO 10 . 5835. " The production of these substances is easily explained. If from choleic acid . . . C H N2 022, We subtract 1 atom taurine C 4 H? NO 10 ) ,-,, Uin , ^.n And 1 atom ammonia . R3 N ] = *> There remains 1 atom choloidic acid . = C K O'2 5836. " Cholic acid. This acid is formed, along with carbonic acid and ammonia, when bile or choleic acid is boiled with an excess of caustic potash. It is precipitated by acetic acid, and purified by alcohol from un- altered choleic acid. 5837. "When pure, it forms fine needles, which are permanent in the air; or large tetraedrons, which become opaque on exposure. It is inso- luble in water, soluble in alcohol and ether. It forms neutral salts with bases. Its formula is C 74 H 60 O 18 , and its formation is easily explained. If from choleic acid C H<* N2 O^, We subtract 2 atoms carbonic acid C 2 O 4 ) ^ Tj fi And 2 atoms ammonia . . N2 Re < ^ ' ' There remains 1 atom cholic acid . = C 74 H 60 O 18 5838. " Berzelius states that the bile is far from being so simple in its constitution as Dema^ay supposes; and by a series of ingenious processes has obtained from the bile a number of different substances, which he has named Biline, Biliverdine, Dyslysine, Fellinic Acid, and Cholinic Acid, besides taurine and cholic acid, as already described. Biline is essentially the same as Demarcay's choleic acid ; and it is probable that most of the others are products of decomposition. But even supposing choleic acid to be composed of two or more different compounds, not isolated by Demar- 578 ORGANIC CHEMISTRY. 9&y, y et > as Liebig has well remarked, (Animal Chemistry, 315) we must not overlook the fact, that it is constant in its composition, and that from this composition we can deduce the principal products of the action of acids and alkalies on bile. It is choleic acid or bile as a whole, whether it be one compound or a mixture of several, to which we have to look for the expla- nation of the changes by which bile may be formed or decomposed. The researches of Berzelius have rendered it probable that choleic acid is not a single compound ; but this does not affect its ultimate composition, nor its relation to decomposing agents. It is also clear that bile is very prone to change in almost all circumstances, and yields a great variety of products, most of which have little physiological interest. For these reasons we shall merely refer the reader to the elaborate paper of Berzelius in the foreign journals. The results of Demargay we have given more in detail ; because, as calculated and interpreted by Liebig, they admit of direct application to physiology. 5839. " When dried bile is acted on by alcohol, the pure bile or choleate of soda is dissolved, and the residue is found to contain mucus, salts, and fatty matter. The latter consist of cholesterine and ordinary fat, and pos- sibly contain a portion of the peculiar fats of brain. The dissolved portion, besides true bile, contains a small portion of soaps of margaric and oleic acids with soda. 5840. " The sugar of bile or picromel of Gmelin, so called from its sweet and bitter taste, appears to be choleic acid or biline, altered by the processes to which it has been subjected. 5841. " Biliary Calculi. The concretions which form in the gall-blad- der, and are often the cause of much suffering, are almost always composed of cholesterine, with more or less colouring matter. Hot alcohol dissolves the cholesterine, and deposits it in shining scales on cooling. These calculi have often a form nearly cubical, and a pearly lustre. 5842. " Lithofellic Acid. This acid has recently been discovered by Goebel in a biliary concretion, and appears to be the chief constituent of the concretions called bezoar stones, which occur in herbivorous animals. According to Ettling and Will, its formula is C 40 H 36 O 8 . It is soluble in 'hot alcohol, and forms a crystalline powder on cooling. It is insoluble in water, and forms with alkalies soluble soaps, with oxides of lead and silver insoluble compounds. It is decomposed by heat, and when acted on by nitric acid yields a new acid. 5843. " According to Liebig, who deduced the above formula from the analysis of Ettling and Will, lithofellic acid may be formed, along with hippuric acid, by the oxidation of choleic acid. j r*i* rrR TWO r*w } C 2 eq. hippuric acid, CSG H'6 N2 O' 1 eq choleic acid, C H<* N* O = S l JJ lit ^ fellic aci j C40 H 36 O 8 and 10 eq. oxygen, O'o ^4^. water, H" O H C?6 R66 N2 Q32 O H N* O32 5844. "Excrements. The excrements of man contain about one-fourth of their weight of solid matter. The ashes of dry faeces amount to 13.58 to 15.00 per cent., and are composed of phosphates and other salts. The excrements also contain nitrogen, and yield ammonia when they putrefy. The value of night-soil as manure depends on the salts and ammonia of the faBces, and also in a great measure on the ammoniacal and other salts of OP ANIMAL SUBSTANCES. 579 the urine. The colour of faeces is generally said to be owing to bile ; but Liebig states that there is only a mere trace of bile, if any, to be found in the freces either of man or animals. The yellow matter of faeces is insolu- ble in alcohol, with the exception of a small proportion, and even that has not the characters of bile. 5845. ''Lymph. The lymph of cellular membrane is water, with a small trace of albumen and of common salt. The lymph secreted by the serous membranes is much more highly charged, containing seven or eight per cent, of albumen and salts. It coagulates when heated, or by the ac- tion of nitric acid. The liquor amnii and the fluid of hydatids is similar; but the fluid of dropsy is said to contain urea, and to have cholesterine sus- pended in it. 5846. "Mucus. This is the secretion of the mucus membranes. When dried, it leaves six or seven per cent, of yellowish solid matter, of which about five parts are mucus, the remainder albumen and salts. Mucus does not dissolve in water, but swells like tragacanth into a viscid mass. It dis- solves in caustic potash. 5847. " Pus is the matter secreted by ulcerated surfaces. When healthy, it is a thick yellowish liquid, formed of opaque globules floating in a clear fluid. When mixed with water, the globules fall, forming a yellow insolu- ble sediment. Pus contains about 14 per cent, of solid matter, and is co- agulated by heat and by acids. It contains albuminous matter, fatty mat- ter, and salts. 5848. " The matter of the globules of pus is similar to that of the glo- bules of blood, or globuline. Pus is distinguished from mucus by the mi- croscope, or by the action of caustic potash, with which pus becomes thick and ropy, while mucus forms a thin solution. Urine and Urinary Calculi. 5849. "Urine. This important excretion is separated from the arterial blood in the kidneys. It has a pale yellow colour, and a peculiar smell. Its density varies from 1.012 to 1.030. It has an acid reaction, or is neu- tral, but never alkaline in a state of health. 5850. " On standing, it deposits a slimy mucus-like substance, secreted from the lining surface of the bladder. This mucus acts as a ferment, and causes the urine, after a time, to undergo decomposition ; for, when it is separated by the filter, the urine may be kept unchanged for a much longer time. 5851. " When spontaneous decomposition has taken place, the urine is alkaline from the presence of carbonate of ammonia, derived from the urea. Urine contains about seven or eight per cent, of solid matter, the remainder being water. 5852. " The characteristic organic principles of urine are urea and uric acid (5359, 5361). The urea* has been recently declared by Cap and * "Anomalous Cyanate of Ammonia; Urea. Discovered by Fourcroy and Vau- quelin in urine, by Wohler as the first organic compound artificially produced. It is a constituent of uric acid, and is contained in the urine in combination with lactic acid (Henry). Urea is also a product of the reaction of cyanogen on water when a solution of that gas is allowed to undergo spontaneous decomposition (Pelouze and Richardson). " Prep. By mixing fresh urine evaporated to the consistence of a syrup at a gen- tle heat, which should never reach that of ebullition, when still warm, with its own volume of colourless nitric acid of sp. gr. = 1.42. If the evaporation has been car. 74 580 ORGANIC CHEMISTRY. Henry to be combined with lactic acid ; but, in repeating their experiments, the editor has always obtained pure urea instead of the lactate. It would appear, therefore, that in some individuals it occurs uncombined, in others ried sufficiently far, the whole will form a thick crystalline mass; to insure this, a small portion of the urine should be tried from time to time. The crystalline mass consists of a compound of nitric acid and urea, which is sparingly soluble in nitric acid. By the action of the nitric acid on the warm solution, heat is developed, and effervescence ensues. This is chiefly owing to the destruction of the colouring mat- ter, and if no external heat is applied, the urea not only is not decomposed, but forms, from the first, nearly white crystals of nitrate. When cold is employed, ac- cording to the method formerly recommended, the crystals are very brown, and are purified with difficulty. It is advisable to separate from the inspissated urine as much as possible of the chlorides it contains, by crystallization, before adding the nitric acid (Cap and Henry). " A solution of the colourless crystals of the nitrate of urea is treated with car- bonate of baryta until it is rendered perfectly neutral ; on evaporating, crystals of nitrate of baryta, and then of urea, will be obtained. The crystals of the latter, by being redissolved in a little cold water, are freed from the last portions of the nitrate of baryta; the solution in alcohol gives crystals of pure urea (Wohler). Gregory states that coloured crystals of urea are best decolorized by a little permanganate of potash, which destroys the colouring matter, but has no action on urea. Any ex- cess of the salt is removed by alcohol, which converts it into peroxide of manga- " Instead of using nitric acid, the concentrated urine may be added to a boiling saturated solution of oxalic acid, when the sparingly soluble oxalate of urea falls, which, after being deprived of its colour by charcoal, may be decomposed into the insoluble oxalate of lime and pure urea, by being digested with pounded chalk (Ber- zelius). It can also be prepared by the decomposition of the cyanate of oxide of silver by sal ammoniac, or of the cyanate of oxide of lead by pure or carbonate of ammonia.* " Prop. Crystallizes in colourless, transparent, four-sided, somewhat flattened prisms, of the sp. gr. 1.35, is soluble in its own weight of cold, and in every propor- tion in hot water, in 4.5 parts of cold, and in 2 parts of boiling alcohol : the aqueous solution has a cooling bitter taste like nitre ; when pure, it is perfectly permanent in the air, is not deliquescent, fuses at 250 into a colourless liquid, is decomposed by a higher temperature into ammonia, cyanate of ammonia, and dry solid cyanuric acid. Alkalies do not cause the separation of ammonia in the cold. Unites with several acids without decomposition to crystallizable saline compounds: by evapo- rating its solution with nitrate of silver or acetate of lead it is decomposed; the pro- ducts being, with the first, nitrate of ammonia and crystalline cyanate of silver; with the second, acetate of ammonia and carbonate of lead. With hyponitrous acid it is instantly decomposed into nitrogen and carbonic acid gases, which are evolved in equal volumes; with chlorine it forms hydrochloric acid, nitrogen, and carbonic acid. When fused with the hydrated alkalies, or heated in concentrated sulphuric acid, it is decomposed together with the constituents of three eq. of water into car- bonic acid and ammonia. Urea contains the elements of cyanate of ammonia (NH 4 O -j- C 2 NO); it may also be considered, according to Dumas, as a second compound of carbonic oxide and amide, in which the quantity of the latter is double that in ox- amide C^ 02 -f 2NH2. " Nitrate of Urea. This compound, when recently precipitated from urine, ap- pears in the form of fine crystalline plates of a brown colour and mother-of-pearl lustre; the purer they are, the more they lose this appearance: a solution of pure urea treated with nitric acid gives a granular white crystalline precipitate, which is soluble in eight parts of cold, but more freely in hot water, from which it crystallizes in broad, scarcely translucent plates ; is sparingly soluble in nitric acid, with which it may be boiled without decomposition. Is composed of one eq. of nitric acid, one of urea, and one of water (Regnault)." * I am surprised the following process is not mentioned : Impure cyanate of pot- ash is prepared by roasting the cyanoferrite of potassium. Aqueous solutions of the cyanate thus obtained, and of sulphate of ammonia, being mingled, the aggregate is subjected to boiling alcohol, which takes up the urea only. On cooling, the urea crystallizes, and may be rendered purer by recrystallization from the same men- struum. Kane, 1164. OF ANIMAL SUBSTANCES. 581 as lactate. It is not known precisely in what state of combination the uric acid occurs; but, when it is not deposited spontaneously, it appears on the addition of an acid, and the spontaneous deposition of it is probably owing to the presence of free acid in unusual quantity. 5853. " The proportion of urea has been found by Lecanu to be tolera- bly uniform in the same individual, but to vary much in different persons. It is larger in adult men than in women, and least of all in old people and very young children. The proportion of uric acid varies in a similar way. The following analysis of urine, by Berzelius, will give a view of the usual composition of human urine : Water ....... 933.00 Urea ...---- 30.10 Uric acid ....... 1.00 Lactic acid, lactate of ammonia, and animal matter ad- hering to them - - - 17.14 Mucus of the bladder ..... 0.32 Sulphate of potash - - - 3.71 Sulphate of soda ..---- 3.16 Phosphate of soda - - - 2.94 Phosphate of ammonia - - - - - 1.65 Chloride of sodium ..... 4.45 Hydrochlorate of ammonia - - 1.50 Earthy matters, with a trace of fluoride of calcium - 1.00 Siliceous earth .... - 0.03 1000.00 5854. " Scharling has recently examined the brown organic matter which gives the colour to inspissated urine, and seems also to be the source of its peculiar odour. He obtained a brown, fusible, resinous mass, having a strong odour of castoreum when dry, and a urinous smell when boiled with water. He calls it oxide of omichmyle, (from 0ft/p, urine,) and supposes it to contain a radical, omichmyle, the composition of which is still unknown. 5855. " When urine is distilled with an excess of nitric acid, there are formed several products, among which Scharling states that he has observed benzoic acid, and an acid containing chlorine derived from the salts of the urine. This acid appears also to be formed when oxide of omichmyle is distilled with nitromuriatic acid. From his analysis, Scharling deduces the formula C 14 H 4 Cl O 3 -f HO, which represents benzoic acid, in which one eq. of hydrogen is replaced by one eq. of chlorine. It is also isomeric with chloride of salicule or chlorosaliculic acid (5336). 5856. "Along with this acid there is formed a volatile greenish-yellow oil, which Scharling found to contain twice as much chlorine, and the ele- ments of nitric acid. This compound he calls nitro-chloromichmyle. When heated with acids, it is decomposed, and yields another oily matter, chloro michmyle. All these observations require confirmation. 5857. "The urine of herbivora is alkaline, and, when the animals are stall-fed, contains, besides urea, hippuric acid ; but when they live in the open air, or are forced to labour, benzoic acid alone is found. 5858. " The urine of the carnivora is acid, and contains phosphates and sulphates of ammonia and soda, as well as uric acid and urea. 5859. "The urine of serpents and of birds is of a soft semisolid consist- ence, and dries into a mass like chalk. It is almost pure urate of ammo- nia, but contains a small quantity of phosphates. 582 ORGANIC CHEMISTRY. 5860. "Urinary Calculi. The most abundant calculi are those of uric acid. They have generally a fawn colour, are soluble in caustic potash, and precipitated from the solution by acids. They also dissolve in nitric acid with the aid of heat ; and the solution, when gently evaporated to dry- ness, leaves a purple stain of murexide. This species of calculus is totally consumed before the blowpipe, leaving a mere trace of ashes. 5861. "Urate of Ammonia occasionally forms a calculus, which is dis- tinguished from the former by giving out ammonia when digested with pot- ash. 5862. " Bone-earth forms a common calculus, which is earthy, soluble in diluted acids, except acetic acid, insoluble in potash, and indestructible by heat. 5863. " Ammoniaco-magnesian Phosphate also occurs pretty frequently. It is the same double salt which forms whenever magnesia, phosphoric acid, and an excess of ammonia, are brought together. It is soluble in acetic acid, and precipitated again by ammonia. It has often a crystalline aspect. When heated, it gives off ammonia, and leaves phosphate of mag- nesia. 5864. " Fusible Calculus. This very common calculus is a mixture of the two preceding. It is white and chalky, and melts easily before the blowpipe. Acetic acid dissolves part of it, hydrochloric acid the rest. 5865. "Oxalate of Lime, or Mulberry Calculus, has a dark-coloured rough surface, and is very hard. It is insoluble in acetic acid ; but, when heated to redness, it is converted into carbonate of lime, which dissolves in acids with effervescence. 5866. " Xanthic Oxide is a rare calculus, first observed by Dr. Marcet. It has a light brown colour, and becomes resinous by friction. It dissolves in caustic potash, and is precipitated from the solution by carbonic acid. It dissolves in nitric acid without effervescence; and, when evaporated, leaves a yellow mass. Its formula is C 5 H 3 N 3 O 2 . 5867. "Cystic Oxide is also very rare. Discovered by Wollaston. It is yellowish-white and crystalline, with a waxy lustre. It dissolves in caustic potash, and is deposited from the solution in hexagonal plates on the addition of acetic acid. It also dissolves in ammonia and the mineral acids; with the latter it forms crystalline compounds. When its solution in potash is heated, ammonia is first given off, and afterwards a combusti- ble vapour, with the odour of sulphuret of carbon. Its formula is C 8 H 6 NS'O*. 5868. "Both the preceding species are entirely consumed before the blowpipe. 5869. " Calculi sometimes occur, in which layers of uric acid alternate with layers of phosphate of lime, ammoniaco-magnesian phosphate, and fu- sible calculus. Changes which occur during the Life, Growth, and Nutrition of Vegeta- bles and Animals. 5870. ** When we consider that the food of vegetables and of animals is either altogether different from their substance, or passes, before being assimilated, into a new form, we cannot hesitate to admit that the nutri- tion and growth of both classes of organized beings depend on chemical agencies, although these operate under peculiar conditions, and are influ- enced by the unknown force which we call Vitality, so as to produce re- OP ANIMAL SUBSTANCES. 583 suits that cannot be imitated by the chemist in his experiments on dead matter. 5871. "The food of vegetables, as far as their organic structure is concerned, consists entirely of inorganic compounds ; and no organized body can serve for the nutrition of vegetables until it has, by the processes of decay or putrefaction, been resolved into certain inorganic substances. 5872. " These are carbonic acid, water, and ammonia, which are well known to be the final products of putrefaction. But, even where these are supplied to vegetables, their growth will not proceed unless certain mineral substances are likewise furnished in small quantity, either by the soil, or in the water used to moisten it. Almost every plant, when burned, leaves ashes, which commonly contain silica, potash, phosphate of lime ; often also magnesia, soda, sulphates, and oxide of iron. These mineral bodies appear to be essential to the existence of the vegetable tissues, so that plants will not grow in soils destitute of them, however abundantly supplied with carbonic acid, ammonia, and water. 5873. " In the process of germination, oxygen is absorbed, heat is given out, and in some cases at least an acid, said to be the acetic, is formed, the use of which appears to be to extract -from the soil the bases necessary for the future progress of the plant. The starch, or albumen of the seed, be- comes soluble, and in the juice undergoes certain changes, by which the woody fibre or lignine, required for the stem and leaves, is produced ; but, as soon as leaves and roots are developed, the further nutrition of the plant depends on their power of absorbing from the atmosphere and the soil the matters which constitute the food of the plant. 5874. " According to Liebig (see his Agricultural Chemistry), the whole of the carbon is now derived from carbonic acid, which is either absorbed from the atmosphere and rain-water by the leaves, or from the moisture and air in the soil by the roots. Its carbon is retained, and its oxygen given out ; this decomposition being effected in the plant at all times when exposed to the action of light, along with a certain temperature. 5875. " The hydrogen and oxygen of vegetables are derived from wa- ter ; and the reader will here observe, that the great mass of vegetables, consisting of lignine, starch, gum, &c. is actually composed of carbon plus water. 5876. " The nitrogen of vegetables is derived chiefly, if not exclusively, from ammonia, which is supplied to them in rain. Liebig has shown be- yond all doubt, that rain-water always contains more or less carbonate of ammonia. If we acidulate pure rain-water with a little sulphuric acid, and evaporate to a small bulk, the addition of lime causes the disengagement of ammonia, easily known by its pungent smell. It is remarkable that the ammonia of rain-water has always a putrid smell, which indicates its origin. In fact, it is derived from the putrefaction of preceding races of animals and vegetables, and must at all times exist in the atmosphere ; although its rela- tive quantity is so small, that it is not easily detected until it has been accu- mulated in rain, which, in passing through the air, dissolves it readily, and conveys it to the earth. 5877. " It is also to be observed, that the soil itself, like all porous bo- dies, possesses the property of absorbing ammonia, and therefore will attract it from the atmosphere. Alumina, peroxide of iron, and humus, all absorb ammonia powerfully. Gypsum (sulphate of lime) and other sulphates con- vert the carbonate of ammonia into the more fixed sulphate, which remains 584 ORGANIC CHEMISTRY. in the soil till absorbed by the roots. This explains in a great measure the use of these ingredients in fertile soils. 5878. " It is only under the influence of light that plants can decom- pose carbonic acid, fixing its carbon and setting free its oxygen. During the night, on the contrary, they undergo a kind of slow combustion, oxygen being absorbed, and carbonic acid formed. But the balance in this curious alternation is vastly in favour of the process by which oxygen is sent into the atmosphere, for, the whole carbon of a forest, for example, being derived from carbonic acid, an equivalent quantity of oxygen must have been liberated ; and this consideration alone enables us to explain the fact, that, notwithstanding the enormous amount of oxygen withdrawn from the at- mosphere by the respiration of animals, by combustion, by putrefaction, and by the action of vegetables during the night, in all of which processes the oxygen is converted into carbonic acid of equal volume, the proportion of oxygen in the atmosphere does not diminish, and that of carbonic acid does not increase. 5879. " From these considerations it appears that there must always exist a balance or fixed proportion between the existing amount of animal and that of vegetable life. Where animals abound, and where men carry on the usual operations of civilized life, there, carbonic acid must be largely formed. But this carbonic acid, in yielding its carbon to vegetation, yields also its oxygen to restore the purity of the air, and support again the respi- ration of men and animals. Again, the decay and putrefaction of both ani- mals and vegetables yield carbonic acid and ammonia, the very substances which form the food of a new race of vegetables ; and these again contri- bute to the nourishment of new animals ; so that, in this unceasing round of chemical changes, the death of one generation supplies the means of life to that which is to follow. 5880. " It has long been the prevailing opinion, that the carbon of plants is derived directly from humus or humic acid existing in the soil, which is supposed to be absorbed in the form of a solution in water, or as humate of ammonia; but it must be admitted, as Liebig has shown, that there is no evidence whatever that humus is directly absorbed by plants. Humus, as it exists in the soil, is almost entirely insoluble in water, and, when a solu- ble form occurs, the solution, however weak, is always of a dark brown colour; whereas the juices of plants, when first absorbed, are colourless. Again, humic acid, as described by chemists, never occurs in soils, but is a product of the action of alkalies on humus, and besides forms solutions as dark-coloured as those of humus. Good fertile soil digested with cold wa- ter yields to it no colour; water, filtering through such soil, passes colour- less, as may be daily observed ; nay, moss-water, which is actually colour- ed brown by humus, is decolorized by passing through a good fertile soil containing humus; finally, a peaty soil, which contains more humus than any other, is notoriously barren. 5881. "On the other hand, the first vegetables which grew on the earth could not have derived their carbon from humus, which is a product of the decay of vegetables, but could only have obtained it from carbonic acid ; and if this source of carbon were then sufficient, there is no reason to look for another. Besides, if we reflect on the extreme luxuriance of vegetation in uninhabited countries, where the soil has never been manured, we cannot fail to perceive that the carbon of that vegetation must have been chiefly derived from the atmosphere ; and when, in addition to this, we find that the proportion of humus in all soils bearing vegetation increases rather than OP ANIMAL SUBSTANCES. 585 diminishes, in spite of the vast amount of carbon annually accumulated and removed in the crops, we are compelled to adopt the same conclusion. 5882. " This latter consideration shows, that the humus and other or- ganic matters in manures do not act directly in furnishing carbon, and that their use chiefly depends on other ingredients. These, as Liebig has de- monstrated, are, first, the ammonia they contain or yield by putrefaction ; and, secondly, the mineral bodies, such as potash, phosphate of lime, &c., found in their ashes. 5883. " But, although there is no evidence that humus is directly absorb- ed by plants, and the phenomena of peat and mossy soils prove, that the soluble forms of humus are unfavourable to vegetation, yet it cannot be doubted that humus or mould, both of the soil and the manures, performs an important function. It slowly and gradually undergoes combustion, yielding a constant and steady supply of carbonic acid in moderate quanti- ty. This is partly absorbed by the roots, and partly rises into the atmos- phere to be absorbed by the leaves ; but, as the proportion of humus in the soil does not diminish, that which is thus consumed is probably restored to the soil by the secretions, or rather excretions, from the roots. 5884. " Humus also probably acts by absorbing and fixing the ammonia of the atmosphere. 5885. " According to the views above stated, which have been admira- bly laid down by Liebig in his Agricultural Chemistry, the chief use of manures is not to supply plants with carbon, but with ammonia and inor- ganic matters. Every plant requires certain mineral substances, without which it cannot prosper ; and a soil is fertile or barren for any given plant, according as it contains these. Thus, the ashes of wheat-straw contain much silica and potash, while the ashes of the seeds contain phosphate of ammonia and magnesia. Hence, if a soil be deficient in any one of these, it will not yield wheat. On the other hand, a good crop of wheat will ex- haust the soil of these substances, and it will not yield a second crop till they have been restored, either by manure or by the gradual action of the weather in disintegrating the subsoil. Hence the benefit derived from fal- lows and from the rotation of crops. 5886. " When, by an extraordinary supply of any one mineral ingre- dient, or of ammonia, a large crop has been obtained, it is not to be expect- ted that a repetition of the same individual manure next year will produce the same effect. It must be remembered, that the unusual crop has ex- hausted the soil probably of all the other mineral ingredients, and that they also must be restored before a second crop can be obtained. 5887. " The salt most essential to the growth of the potato is the double phosphate of ammonia and magnesia ; that chiefly required for hay is phos- phate of lime; while for almost all plants potash and ammonia are highly beneficial. 5888. "From the principles above mentioned we may deduce a few valuable conclusions in regard to the chemistry of agriculture. First. By examining the ashes of a thriving plant, we discover the mineral ingredients which must exist in a soil to render it fertile for that plant. Secondly. By examining a soil, we can say at once whether it is fertile in regard to any plants, the ashes of which have been examined. Thirdly. When we know the defects of a soil, the deficient matters may be easily obtained and added to it, unmixed with such as are not required. Fourthly- The straw, leaves, &c. of any plant must be the best manure for that plant, since every vegetable extracts from the soil such matters alone as are essential to it. 586 ORGANIC CHEMISTRY. This important principle has been amply verified by the success attending the use of wheat-straw or its ashes as manure for wheat, and of the clip- pings of the vines as manure for the vineyard. Where these are used, no other manure is required. Fifthly. In the rotation of crops, those should be made to follow which require different minerals; or a crop which ex- tracts little or no mineral matter, such as peas, should come after one which exhausts the soil of its phosphates and potash. 5889. " Of the chemical manures now so much used, bone-dust supplies the phosphates, which have been extracted by successive crops of grass and corn, the whole of the bones of the cattle fed on these crops having been de- rived from the soil ; its gelatine also yields ammonia by putrefaction. Gu- ano acts as a source of ammonia, containing much oxalate and urate of ammonia with some phosphates. Night-soil and urine, especially the lat- ter, are most valuable for the ammonia they yield, as well as for phosphates and potash : but are very much neglected in this country, although their importance is fully appreciated in Belgium and China. Bran is a very valuable manure, especially for potatoes, as it contains much of the ammo- niaco-magnesian phosphate. 5890. " Nitrate of Soda probably acts by its alkali, replacing potash, but it is possible that its acid may also yield nitrogen to plants, although we possess at present no evidence of this, and indeed no evidence that plants can derive their nitrogen from any other source than from ammonia. 5891. "Such is a brief sketch of the general laws of vegetation as at present known, in so far as they are connected with chemistry. Of the changes in the juices of vegetables, by which the numerous products of the vegetable kingdom are formed, we know nothing. The juices of plants contain ammonia and sugar, gum or starch ; all the elements are therefore present from which the nitrogenized compounds, albumen, fibrine, and caseine, in other words, proteine, may be formed, and it appears that vege- tables alone can produce proteine. Thus the final products of vegetation form the food of animals; the modifications of proteine serving for nutri- tion, properly so called, and the starch, gum, sugar, and oil serving for the support of respiration. 5892. " The life of animals is distinguished chemically from that of vegetables by the circumstance, that in the former oxygen is constantly absorbed and replaced by carbonic acid, while in the latter carbonic acid is absorbed, its carbon retained, and its oxygen given out. Consciousness and the power of locomotion are peculiar to animals. 5893. " In animals two processes are constantly carried on ; that of respiration, by which the animal heat is kept up ; and that of nutrition, by which the matter consumed in the vital functions and expelled from the body is restored. 5894. " Respiration is essentially a combustion of carbon, which in com- bining with oxygen is converted into carbonic acid, and at the same time furnishes the animal heat. Liebig calculates that the amount of carbon daily burned in the body of an adult man is about fourteen ounces, and that the heat given out is fully sufficient to keep up the temperature of the body, and to account for the evaporation of all the gaseous matter and water expelled from the lungs. 5895. " This carbon is derived in the first place from the tissues of the body, which undergo a constant waste, but ultimately from the food. 5896. " In the carnivora, whose food is almost entirely composed of compounds of proteine, albumen, &c. one part is devoted to supply the OF ANIMAL SUBSTANCES. 587 waste of the tissues, while another portion, or a corresponding amount of previously existing tissue, is decomposed so as to yield the carbon required for respiration. As the tissues can only be decomposed by the exercise of the vital functions, this is the reason why, in the carnivora, an enor- mous amount of muscular motion is required to furnish the necessary sup- ply of carbon. 5897. " On the other hand, the food of the herbivora contains but little of the compounds of proteine, only sufficient to restore the waste of the tissues ; while the carbon required for respiration is supplied by the starch, gum, sugar, oil, &c. which form the great mass of their food, and no such amount of muscular motion is required in them as in the carnivora. 5898. " It is in the form of bile chiefly that the carbon undergoes com- bustion. Hitherto, the true function of the bile has been disputed; and by most authors that fluid has been considered as an excretion, intended to be expelled from the body in the fseces. But Liebig has shown that only a small fraction of the whole amount of bile can be detected in any shape in the fseces, and that the bile unquestionably is reabsorbed in the intestinal canal, and re-enters the circulation, where it soon disappears ; and as the proportion of carbon in the bile is very large, although not sufficient to account for all the carbonic acid given out, there is no reason to doubt that it is gradually consumed by the oxygen of the arterial blood, and convert- ed into carbonic acid and water, which escape by the lungs and skin. 5899. " To return to the subject of the animal heat : the food that is required, and hence the appetite, must be proportional to the amount of carbon required to supply the animal heat. Now, in hot climates, where the external cooling is less, less heat is required, the appetite is much more feeble, and the usual food, consisting of fruits and vegetables, contains a far smaller amount of carbon than in cold climates, where the appetite is keen, and the food highly carbonized, such as flesh, or even blubber. For the same reasons, warm clothing, by diminishing the loss of heat by ex- ternal cooling, blunts the appetite ; and those who remove from a cold to a warm climate always find that their appetite fails. This is a warning from nature to diminish the amount of food taken ; and if it were attended to, and the common but absurd practice of stimulating the appetite by ardent liquors and hot spices abandoned, Europeans might enjoy as good health in the East or West Indies as at home. It is obvious that, even in Europe, more food is required in winter than in summer. (Animal Chemistry, 23.) 5900. " In endeavouring to explain the formation of the bile, it is ob- viously of no moment whether we derive it from the albumen, fibrine, &c. of the food, or those of the tissues, their composition being identical. Liebig, assuming choleic acid to be the chief organic constituent of the bile, and its formula to be C 78 N a H 86 O 23 , has shown that the half of this formula, added to that of urate of ammonia, C 10 H 5 N 7 O 8 , which gives the sum C 48 N 6 H 40 O 17 , is equal to the formula of blood or flesh, C 48 N 6 H 39 O 15 , with the addition of one atom water and one atom oxygen. (Animal Chemistry, 135, 136.) Again, proteine, C 48 N 6 H 36 O 14 , plus three atoms of water, gives the same sum, excepting one atom of hydrogen, viz. C 48 N 8 H 39 O 17 . In this way we can see how the tissues, acted on by oxygen and water, may yield the ingredients of bile and urine. This is the first attempt which has been made to trace chemically the connection between the food, the blood or the tissues, and the secretions or excretions ; and showing, as it does, that these questions are capable of elucidation on chemical principles, it 75 588 ORGANIC CHEMISTRY. must be regarded as the most important idea yet suggested in animal che- mistry. 5901. " Supposing it to be well-founded, the tissues which are consumed are resolved first into bile and urate of ammonia. The former is secreted from the liver, reabsorbed and burned, as before stated. The latter, in ser- pents and birds, is expelled unchanged ; but in man and quadrupeds, in whom the amount of oxygen inspired is much greater, it is also oxidized, yielding finally carbonic acid, ammonia, and urea. 5902. " Should the supply of oxygen in the human subject be insuffi- cient to act on the urate of ammonia, then the uric acid is deposited as gravel or calculus ; if the supply of oxygen be somewhat greater, but still deficient, oxalic acid is the result, and mulberry calculus occurs ; but, if much exercise be taken and abundance of oxygen supplied, the oxidation of the uric acid is completed, and nothing is left but urea or carbonate of ammonia. 5903. " This explains the true cause of uric acid and mulberry calculus to be a deficiency of oxygen; it also explains why uric acid calculus is fol- lowed by mulberry calculus in those who remove from the town to the country, where more exercise is taken ; and from these considerations we may see how valuable are the results which will flow from a thorough in- vestigation of all departments of animal chemistry. 5904. " The urine of the herbivora differs from that of man, in contain- ing, besides urea, hippuric acid when they are at rest or stall-fed, and ben- zoic acid when they are in full exercise, and when consequently more oxygen is supplied. Liebig has shown, that, if to five times the formula of blood, we add nine atoms of oxygen, we have the elements of six atoms hippuric acid, nine atoms urea, three atoms choleic acid, three atoms am- monia, and three atoms water; and that, if to five times the formula of blood we add forty-five atoms oxygen, we obtain the elements of six atoms benzoic acid, thirteen and a half atoms urea, three atoms choleic acid, fifteen atoms carbonic acid, and twelve of water. Moreover, two atoms proteine, with two atoms of water, contain the elements of six atoms allantoine (found in the urine of the foetal calf), and one atom choloidic acid, which is sup- posed to be the same as the meconium. 5905. " The bile of the herbivora is much more abundant than that of the carnivora, an ox secreting, according to Burdach, 37lbs. of bile daily. As the waste of matter in the herbivora is but limited, it is obvious that it cannot supply all the bile, and consequently a great part of it must be de- rived from the starch and other nonazotized constituents of their food, which lose oxygen, and enter into combination with some azotised product of the decomposition of compounds of proteine. 5906. " In order to show how this is possible, Liebig points out that the elements of two atoms of proteine, with those of three atoms uric acid and two atoms oxygen, amount to the same sum as six atoms hippuric acid and nine atoms urea ; while, if to five atoms starch we add two atoms hippuric acid and two atoms oxygen, the sum is equal to two atoms choleic acid and twenty atoms carbonic acid. 5907. " Again, if the elements of proteine and starch, oxygen and water being present, undergo transformation, and mutually affect each other, the products of this metamorphosis may be urea, choleic acid, ammonia, and carbonic acid. Thus : OP ANIMAL SUBSTANCES. 589 5 atoms proteine, 5 (C N* H O") = C* Nao H'80 O 15 starch, 15 (C* H'O') = O e <> H'5O'> H'2 And 5 oxygen, = 05 The sum is - c-120 N 30 H 342 O 837 . 9 atoms choleic acid, 9 urea, 3 ammonia, 60 carbonic acid, 9 9 3 60 (ON (C2 NS C N (C H33Q") H3 ) 02) C342 N9 = N3 --60 H297Q99 H9 Q120 The sum is = 020 N3 H^ Q237 5908. " The reader will observe that these equations are given, not as representing what is actually proved to occur, but only to show how such changes may be conceived on ordinary chemical principles. But it is to be borne in mind, that all the necessary substances meet in the circulation ; proteine and starch from the food, oxygen in the arterial blood, and that water is never absent: while the resulting products are the chief constituents of the secretions and excretions; viz. carbonic acid, excreted by the lungs; urea and carbonate of ammonia, excreted by the kidneys; and choleic acid, secreted by the liver. (Animal Chemistry, 150 et seq.) 5909. " We have thus seen how the carbon in the form of choleic acid or bile, may be obtained in a state most favourable for its oxidation or com- bustion. But, if the supply of oxygen be deficient, the choleic acid may by a partial oxidation yield hippuric and lithofellic acids, just as we have seen that uric acid, partially oxidized, yields oxalic acid ; for two atoms choleic acid +10 atoms oxygen are equal to two atoms hippuric acid, one atom lithofellic acid, and fourteen atoms water. Thus one species of biliary cal- culus, identical with the bezoar stones found in the herbivora, may have an origin similar to that of the mulberry calculus, both arising from a deficient supply of oxygen. (Liebig.) 5910. " Soda is necessary to the formation of bile, and is supplied in the form of common salt. Where the supply of soda is defective, the meta- morphosis of proteine can yield only fat and urea. If we assume for fat the empirical formula C 11 H 10 O, then two atoms proteine, with twelve atoms water, and fourteen atoms oxygen, in all C 96 N 13 H 84 O 54 , are equal to six atoms urea, six atoms fat, and eighteen atoms carbonic acid. If we assume fat to be C ia H 10 O, a similar result may be traced ; and the composition of all fats lies between these two empirical formula?. Now, it is worthy of ob- servation, that, if we wish to fatten an animal, we must carefully avoid giving much salt in its food. (Liebig.) 5911. " As another point of connection between the products of the me- tamorphosis of bile and of the constituents of urine, in addition to the pos- sibility already mentioned of both being derived from the oxidation of pro- teine, it may here be remarked, that three atoms taurine and three atoms ammonia are equal to one atom uric acid, one atom urea, and twenty-two atoms water; and that one atom taurine and one atom ammonia are equal to one atom allantoine and seven atoms water. (Liebig.) 5912. " It may further be noted that one atom uric acid, fourteen atoms water, and two atoms oxygen, correspond to two atoms taurine and one atom urea; or, if two atoms water be added, to two atoms taurine and two atoms carbonate of ammonia. Moreover, one atom alloxan and ten atoms 590 ORGANIC CHEMISTRY. water are equal to two atoms taurine ; and one atom taurine contains the elements of two atoms oxalic acid, one atom ammonia, and four atoms wa- ter. (Liebig.) 5913. " As alloxan is a product of the oxidation of uric acid, and as it has been shown above to be related to taurine, that is, to bile, it would be very important to study its action on the system. It might probably act beneficially in some diseases of the liver. It may be safely administered in considerable quantity. (Liebig.) 5914. " In the urine of the carnivora we find soda in moderate quantity, combined with sulphuric and phosphoric acids. This soda was contained in their food, and, after contributing to form the bile, has been secreted by the kidneys. But it is never sufficient to neutralize the acids produced, and consequently we find much ammonia along with it, while the urine is acid. 5915. "But in the urine of the herbivora soda is present in far larger quantity, and combined with carbonic, hippuric, or benzoic acid. This shows that the herbivora require a far greater amount of soda than is con- tained in the amount of blood daily consumed, which in them is small ; and this soda is obtained from their food, and employed in producing their abun- dant bile. 5916. " The plants on which the herbivora feed cannot grow in a soil destitute of alkalies; but these alkalies are not less necessary for the sup- port of the animals than of the plants. The soda is found in the blood and bile ; and the potash is now known to be absolutely essential to the produc- tion of caseine, that is, the secretion of milk. In like manner, the phosphate of lime, which is essential to the growth of grasses, is equally essential to the production of bone in the animals which feed on these plants. It is im- possible not to be penetrated with admiration of the wisdom which is shown in these beautiful arrangements. 5917. " Let us now consider the changes which the food undergoes in the process of digestion, and we shall observe this process in the carnivora, where it is most simple, as their food is identical in composition with their tissues. 5918. " When the food has entered the stomach, the gastric juice is poured out, and after a short time the whole is converted into a semifluid, homogeneous mass, the chyme. Many researches have been made to dis- cover the solvent contained in the gastric juice, but in vain. It contains no substance which has the property of dissolving fibrine, albumen, &c.; and we are compelled to adopt the opinion of Liebig, according to which the food is dissolved in consequence of a metamorphosis, analogous to fermen- tation, by which a new arrangement of the particles is effected. As, in fermentation, the change is owing to the presence of a body in a state of decomposition, or motion, which is propagated from the ferment to the sugar by contact; so, in digestion, the gastric juice contains a small quantity of a matter derived from the lining membrane of the stomach, which is in a state of progressive change, and the change or motion is propagated from this to the particles of the food under certain conditions, such as a certain tempe- rature, &c. 5919. " The phenomena of artificial digestion confirm this view. If the lining membrane of a stomach, perfectly clean and fresh, be infused in wa- ter feebly acidulated with chlorohydric acid, the liquid acquires no solvent action on albumen ; but if the membrane be exposed to the air for some time, or be left in water for a while, in short, if decomposition be allowed OF ANIMAL SUBSTANCES. 591 to commence, then the infusion, if coagulated albumen or fibrine be placed in it, and the whole kept at the temperature of the body, by degrees effects a perfect solution or digestion. 5920. " Prout has shown that the gastric juice contains free chlorohy- dric acid. This is derived from the common salt, the soda of which com- bines with the albumen or fibrine, while its acid, being set free, at length by its accumulation checks further change. Besides the gastric juice, the only other substance employed in digestion is the oxygen which is intro- duced into the stomach with the saliva, which from its viscidity encloses a large quantity of air. The chyme then leaves the stomach, and gradually passes into the state of chyle, which resembles blood, except in colour, being already alkaline, not acid like the chyme. 5921. " By means of the circulation oxygen is conveyed in the arterial blood to every part of the body. This oxygen, acting on the tissues des- tined to undergo change, produces a metamorphosis, by which new soluble compounds are formed. The tissues thus destroyed are replaced by the new matter derived from the food. Meantime, those of the products of me- tamorphosis which contain the principal part of the carbon, are separated from the venous blood in the liver, and yield the bile; while the nitrogen accumulates, and is separated from the arterial blood in the kidneys in the form of urea or uric acid. 5922. " It has been already mentioned, that vegetables alone possess the power of forming proteine, which they furnish to animals in the forms of albumen, fibrine, and caseine. In the animal body these forms of proteine are employed to yield the different tissues, most of which bear a simple re- lation to proteine. Thus, Fibrine, albumen, caseine, are Pr + S -f- P + salts. Arterial membrane is - - Pr -j- 2HO. Chondrine is - - - - Pr-f 4HO -}- (X Hair, horn, &c., are - - Pr + NH3 -f Q3. Gelatinous tissues are - - 2Pr -f 3NR3 + HO -j- (X 5923. " It is not meant that these formulas express the actual constitution of the tissues, but only that they give the proportion of the elements actually present, and show how they might give rise to the tissues. Some of these tissues contain proteine, or at least yield it when acted on by potash : this is the case with hair and horn. But others, as, for example, the gelatinous tissues, although doubtless derived from proteine, do not contain it, and con- sequently cannot yield any of its modifications. This explains the fact that gelatine alone cannot support animal life. It cannot yield blood or muscular fibre, although it may serve to nourish the gelatinous tissues. (See Gelatine.) 5924. "Liebig has shown (Animal Chemistry, p. 141), that gelatine may be formed from proteine in two ways; either by adding to two atoms proteine three atoms allantoine and three atoms water (which are equal to one atom uric acid, one atom urea, and four of water), or by subtracting from three atoms proteine half an atom choloidic acid, and adding four atoms water. These statements apply to Mulder's formula for gelatine; but as the true formula is still doubtful, they are only mentioned to show the method by which we may hope to arrive at accurate results. 5925. " There is another constituent of the animal body, namely fat, the production of which deserves notice. It is not an organized tissue, but is formed and collected in the cellular tissue under certain circumstances. 592 ORGANIC CHEMISTRY. These are rest and confinement, that is, a deficiency of oxygen, and an abundance of food devoid of nitrogen. Carnivorous animals are never fat; and the herbivora only become so in confinement. 5926. " Now the chief source of fat is starch, or sugar, the composition of which is such, that, if deprived of oxygen, fat remains. If from starch, C ia H 10 O 10 , we take nine atoms oxygen, there remains C 13 H 10 O, which is one of the empirical formulae for fat. Or if from starch we remove one atom carbonic acid, CO 2 , and seven atoms oxygen, the remainder, C 11 H 10 O, represents the other empirical formula of fat. We have already seen how fat may be derived from proteine when soda is deficient ; and we may here add, that all the elements of food contain more oxygen than fat, in propor- tion to the carbon. Thus, in albumen, fibrine, and caseine, for 120 eq. carbon there are contained 36 eq. oxygen; in starch, for 120 eq. carbon, 100 eq. oxygen; in sugar and gum, 110 eq. oxygen; in sugar of milk, 120 eq.; and in grape-sugar, 140 eq. oxygen; while in fat there are only 10 eq. oxygen for 120 eq. carbon. 5927. " It is obvious, therefore, that fat can only be formed by a process of deoxidation. But we have seen that it is produced where oxygen is de- ficient ; and it appears, as Liebig has pointed out, that when there is a defi- cient supply of oxygen, the production of fat, which is the consequence of this deficiency, yields a supply of that element, and thus serves to keep up the animal heat and the vital functions, which would otherwise be arrested. This is another beautiful instance of contrivance, equally simple and won- derful. 5928. " That fat must be formed by the deoxidizing process above al- luded to, is proved by the phenomena of the fattening of animals. A goose, tied up, and fed with farinaceous food altogether destitute of fat, ac- quires, in a short time, an increase in weight of several pounds, the whole of which is fat. Again, the bee produces wax, a species of fat, from pure sugar. 5929. " With regard to the production of nervous matter, which animals alone can form, we see, from its composition, intermediate between that of proteine and fat, that it may be formed, either by depriving proteine of some nitrogenated product, or by adding such a product to fat. Where it is formed we do not know ; but it must be formed in the animal body : and Liebig has suggested that the power of the vegetable alkalies to affect the nervous system, may be owing to their composition, which approaches nearer to that of nervous matter than any other compounds. These alka- lies may promote or check the formation of nervous matter, and thus pro- duce their peculiar effects. 5930. " In like manner, certain vegetable products analogous to the ve- getable alkalies, such as caffeine (or theine) and theobromine, may be sup- posed, according to Liebig, to promote the secretion of bile, their compo- sition being related to that of some of the products of bile. 5931. "Thus one atom caffeine (or theine), with nine atoms water and nine atoms oxygen, may yield two atoms taurine. Again, one atom theo- bromine, with twenty-two atoms water and sixteen atoms oxygen, corres- ponds to four atoms taurine and one atom urea; or one atom theobromine, eight atoms water, and fourteen atoms oxygen, contain the elements of two atoms taurine and one atom uric acid. (Animal Chemistry, 180.) 5932. " Now it is surely very remarkable, that the vegetables containing these compounds, tea, coffee, and cocoa, should be, one or other of them, used by almost all nations to yield a refreshing drink; and it is still more OF RESPIRATION. 593 curious that the peculiar principle of tea should turn out to be identical with that of coffee, as recent researches have demonstrated. 5933. " We may suppose, with some degree of probability, that where the formation of bile, and consequently that of urine, which is connected with it, does not go on as it ought, the use of these beverages, by promoting the secretion of bile, may assist the process of respiration, promoting the animal heat, and, at the same time, contributing to the due performance of all the vital functions. At all events, neither the beneficial and refreshing effects of these articles of diet, nor their relation to bile and urine, can be overlooked ; and the universal adoption of the practice of using tea, coffee, or chocolate, is a proof that men have discovered and obtained from dif- ferent sources the means of producing the same effect. 5934. " The preceding observations are sufficient to show that we may expect, in progress of time, to explain the action of all remedies on chemical principles. The true path has been opened up, and it only remains for ex- perimenters to pursue it with energy and perseverance." OF RESPIRATION. 5935. The quotation from Gregory's work being con- cluded, I subjoin an article which I had prepared on respi- ration, as it contains some ideas which are not found in the preceding matter, and some objections to Liebig's ex- planation of the phenomena of that process. 5936. Chemistry demonstrates, that during this process, the volume of the air respired by animals is diminished, but that a portion of the oxygen is replaced by an equal bulk of carbonic acid. Although, at one time, by respect- able observers, the volume of this last mentioned gas was alleged not to be uniformly equal to that of the absorbed oxygen, the ratio of the one to the other, being represented as varying with the time of day and the season, not only in different animals, but also in the same animal, later ob- servation seems to have produced a general opinion, which is zealously espoused by the distinguished chemist above mentioned, that the expired carbonic acid is, upon the whole^ exactly equivalent to the oxygen consumed. 5937. The prevalence of nitrogen, in animal substances, naturally led to the idea that it might be assimilated more or less during respiration; but experience has led to an opposite opinion; and Liebig has endeavoured to show, that in the nutriment of granivorous animals, there is no deficiency of vegeto-animal matter having as large a pro- portion of nitrogen as flesh and blood* (5023). * I subjoin the following opinion of Berzelius. Report for 1840, page 313. " The question has often been put, whether animals assimilate nitrogen during respiration. In examining air which has been breathed by them, it has been found 594 ORGANIC CHEMISTRY. 5938. When first, by the Lavoiserian school, the heat of all ordinary fires was shown to be attributable to the union of oxygen with the combustible employed, the idea naturally followed, that respiration being attended by a like union of oxygen with combustible matter, animal heat ought to be ascribed to this source. Many objections to this explanation of the origin of animal heat were subse- quently urged, and, among others, the fact that the heat of the lungs, the fire place, is no higher than remoter parts of the animal frame. 5939. To remove this objection, Crawford suggested that the capacity for heat, of arterial blood, being greater than that of venous blood, caloric was taken up by the blood in one state, to be evolved when in the other. This suggestion respecting the relative capacities for heat, of arterial and venous blood, has not been supported by sub- sequent experience; and another view of the subject has been taken, which renders it quite consistent that the tem- perature should not be peculiarly high in the lungs. 5940. It is supposed that the blood merely absorbs oxy- gen in the lungs, but that this oxygen is carbonized during its circulation, and thus causes heat to be given out in all parts of the system. The carbonic acid thus produced, on reaching the lungs in combination with the venous blood, is exchanged for oxygen, and consequently expired with the breath. 5941. Liebig conceives that the iron in the hematosin of the red globules is held by the arterial blood, in the state of hydra ted sesquioxide; but in the capillaries, the sesquioxide passing to the state of protoxide, by yielding oxygen to the carbon in the blood, combines with the ear- that in some cases a deficit of nitrogen has ensued, in others an excess, while in others, again, the proportion has remained unchanged. Yet rigorous experiments have proved, that the nitrogen of respired air is quite passive, and cannot be assimi- lated during respiration : moreover, that the blood, in common with all other liquids in contact with the air, contains nitrogen and oxygen in the proportion in which they are present in the gaseous mixture employed ; so that when a mixture, con- taining more nitrogen, is respired, a greater quantity is absorbed. When the mix- ture, under like circumstances, has an inferior quantity of nitrogen, this principle is given out by the blood. It may be assumed, that experiments have completely de- cided that the proportion of nitrogen in the animal frame is altogether independent of the quantity of air respired." It does not, however, appear to me to be true, that all liquids in contact with air take up its ingredients in the same proportion ; or if they do, that they continue to hold them in that proportion, uninfluenced by the chemical affinity between their constituents and oxygen. OF RESPIRATION. 595 bonic acid thus produced, and gives rise, in the venous blood, to a carbonated protoxide. 5942. When the venous blood reaches the lungs, the protoxide exchanging carbonic acid for oxygen, this gas is expelled with the breath, while the regenerated sesquioxide is again, by union with water, reconverted into a hydrate. The well known change of hue which follows the transfer of the blood from the veins to the arteries, through the pulmonary organs, seems to be considered as a collateral consequence of these chemical reactions. Yet this change does not appear to me sufficiently accounted for, since no such alteration of colour can be produced by the transfor- mation of a carbonated protoxide of iron to a hydrated sesquioxide. Moreover, the fact that no peculiar elevation of temperature takes place on the surfaces where the ve- nous blood meets the breath, seems to me inconsistent with Liebig's explanation, since the heat must be extri- cated in the space where the iron is peroxidized. 5943. Upon the whole I now think as 1 have for forty years, whatever other opinions may have prevailed, that there must be a degree of heat derived from respiration proportioned to the quantity of oxygen converted into car- bonic acid; but with all due deference for Liebig, I do not agree with him, that it is possible to give a satisfactory explanation of this process upon purely chemical affinities, such as exist independently of vital power. It appears to me that nature has the power, within certain limits, of making chemical affinities to suit her own purposes, and can therefore cause the oxygen to be absorbed, the carbon to combine therewith, and the heat to be given out when and where the processes of vitality require it. If nature have not the alleged power, how does it happen that, out of the heterogeneous congeries of elements existing in the egg, the bill, the claws, the feathers, the bones, the blood, and flesh, are made to appear at the various stations, at which their presence is requisite, for the existence of a young bird?* * Mr. Winn, (L. and E. Phil. Mag. 174,) considers the extension and contraction of the fibrous tissues of the arteries, during pulsation, as among the causes of animal heat. It is well known that caoutchouc grows warm when rapidlj extended ; and Mr. Winn found a portion of the aorta of an ox to be capable of a similar rise of tem- perature, when, during two minutes, it was made to undergo turgescence, and col- lapse similar to that which takes place during pulsation. To have decided this ques- 76 596 ORGANIC CHEMISTRY. 5944. Liebig cites the following interesting facts. An active man expires 13.9 ounces of carbon, and daily con- sumes, in the same time, 37 ounces of oxygen = 51,648 cubic inches, or about 223 gallons. Reckoning 18 inspi- rations per minute, there must be 25,920 consumed per day, and consequently fiftt = 1.99, or nearly two cubic inches of oxygen in each respiration. In one minute, therefore, there are added to the blood 1.99 x 18 = 35.8 cubic inches of oxygen, weighing rather less than twelve grains. 5945. In one minute, ten pounds of blood pass through the lungs, measuring 320 cubic inches, among which 35.8 being divided, there must be one cubic inch of oxygen for nine of blood nearly.* 5946. Ten Hessian pounds of blood = 76,800 grains, if in the arterial state, contain 6lT 5 w grains sesquioxide of iron; if in the venous state, 55-njV of protoxide.t 6 T 4 w, the difference, is the quantity of oxygen which the iron of the venous blood can acquire in the lungs, which, deducted from twelve grains, the whole quantity of oxygen absorbed, leaves 5.60 grains requiring some other means of absorp- tion. But 55ro 4 o grains of protoxide of iron would take up 73 cubic inches of carbonic acid, which is double the vo- lume that the 35-dhr of oxygen can generate. 5947. One glaring defect in this part of the explanation, arises from the admitted fact, that nearly one-half of the absorption of oxygen is unaccounted for ; 5.60 in twelve parts. OF FERMENTATION. 5948. Certain spontaneous changes which ensue in organic substances, by which they are more or less decomposed or resolved into new combina- tions, have been generically designated under the name of fermentation. 5949. For a long time only three kinds of fermentation had been recog- nised, called, severally, the vinous, the acetous, and the putrefactive; but now we have several others added to the list, among which are the saccha- rine, and the viscous or lactic. 5950. The production of cyanhydric acid (1323) by the reaction of tion, the author should have shown that heat might be permanently caused by the extension and contraction either of caoutchouc or the ox artery. But were it de- monstrated that heat could be thus permanently generated, there would be no less difficulty in explaining how the organic substances employed could thus give rise to heat. It involves the question of the materiality of caloric, since, if material, a per- manent supply could not be derived from an isolated strip of caoutchouc. * Stated upon the authority of Muller. " Physiologic, Vol. 1, p. 345." t Deduced from the Researches of Denis Richardson and Nasse, Handworterbuch der Physiologic, Vol. 1, p. 138. Note. Measures and weights are Hessian. OF FERMENTATION. 597 emulsine with amydaline (3055), that of the oil of mustard by myrozine and myronic acid (5091), are, by Boutron and Fremy, considered as cases of fermentation; and to these, it seems, we may add the generation of ni- cotin, which is alleged to be the effect of a species of fermentation promoted in the leaf of the tobacco plant after it has been gathered. 5951. To the saccharine, the vinous, acetous, and viscous or lactic fer- mentation, allusion has already been made in treating of starch (4082); of cane sugar (4057); of alcohol (5578); of lactin (4070); acetic acid (5197); lactic acid (5215). Of the Saccharine and Vinous Fermentations. 5952. The saccharine fermentation is exemplified in the change which takes place in the mash or wash of the distiller, by which the starch of the grain, C ia H 10 O 10 , takes two atoms of water, 2HO, to form dry grape su- gar, C 13 H 12 O 12 . 5953. The vinous fermentation ensues in all cases where alcohol is pro- duced by an internal change in organic solutions. By some chemists, it is supposed that alcohol is produced only when grape sugar is present at the outset, or generated subsequently ; since it is alleged that cane sugar and other saccharine substances must be converted into grape sugar before they can enter into the vinous fermentation. It has been stated, that by this fermentation an atom of grape sugar is resolved into the elements of two atoms of alcohol and four atoms of carbonic acid (5578). 5954. The juice of the apple, the pear, or the grape, at any temperature above 50, spontaneously enter into the alcoholic fermentation. This is ascribed to the existence, in them, of a vegeto-animal matter, which being first oxidized, afterwards mysteriously causes the sugar to be resolved into alcohol and carbonic acid, as already stated (5578). The preservation of fruits and other organic substances by heat, in well closed vessels, is as- cribed to the prevention of that oxidizement of the vegeto-animal ferment, which is the necessary precursor of fermentation. 5955. In the case of wort as prepared in breweries, there is great diffi- culty in inciting a proper vinous fermentation, without the assistance of yeast arising from a preceding process. Yet during every well conducted operation, a large quantity of this substance has to be thrown off. The thorough performance of this process, called cleansing, has always been known to be necessary to the flavour of the beer; but Liebig alleges that it also lessens the liability to acetification, and that by a process practised in Bavaria, the yeast being more thoroughly removed by deposition, such a superiority was attained as respects insusceptibility of sourness, that large premiums were offered in other German states for those who should suc- ceed in imitating that process. This consists in the exposure of the beer, in open shallow vessels, to atmospheric oxygen, at a temperature below 50, by which the vegeto-animal matter which forms the yeast, is oxidized and precipitated at a temperature too low for that simultaneous conversion of the alcohol into acetic acid, which would be the consequence of a higher tem- perature under like circumstances. 5956. During fermentation there is a commensurate attenuation of the liquor, of which the extent may be ascertained by the hydrometer. In fact, this instrument and a thermometer are indispensable to enable a manufac- turer to conduct well any fermenting process. The hydrometer shows that diminution of density which measures the gain in alcohol. This attenua- 598 ORGANIC CHEMISTRY. tion is estimated roughly by the change in the froth or head, which, while the presence of saccharine matter is abundant so as to envelope the car- bonic acid, rises high, but gradually falls as the solution becomes thinner, until, in consequence of the formation of the yeast, a new head rises, formed of that viscid matter. Of the Acetous Fermentation, a Process of Acetification. 5957. To acidify, signifies to produce any species of acidity; but the application of the word acetify is confined to those processes by which ace- tic acid is produced, of which there are several. 5958. Of the processes alluded to, that by which fermented and spirituous liquids are made to generate acetic acid in the form of vinegar, has been designated as the acetous fermentation being accompanied by an apparent intestinal reaction between the ingredients in the liquid mixture or solution, which undergoes this acetifying process. This fermentation differs from the vinous in requiring an extraneous supply of atmospheric oxygen, by which, as has been mentioned, ethyl is changed into acetyl by the oxidation of two atoms of hydrogen, and the acetyl is afterwards acidified by the acquisition of two more such atoms (5197), so that, from a hydrated prot- oxide of ethyl, a hydrated trioxide of acetyl arises. 5959. Yet alcohol, whether strong or dilute, does not, per se, undergo the change just described. The presence of some substance which may attract oxygen from the air, appears necessary to cause its acetification. Thus dilute alcohol and water do not ferment ; but a mixture of one part of honey and one of crude tartar to thirteen of alcohol and one hundred of water, will, in warm weather, produce vinegar in a few weeks (5197). The change effected in the alcohol may be understood from the formulae already given. 5960. The usual method of producing vinegar by the exposure of liquors in open vessels, demonstrates that the necessity of atmospheric oxygen had been learned in practice. Latterly, the process has been greatly expedited by allowing the liquor to fall, in drops, upon the shavings of beach wood, the temperature being kept up nearly to 100. According to Liebig, in this way one part of spirit of wine, containing eighty per cent, of alcohol with about five parts of water and Yw?r tn f y east of honey or other ferment, may be converted into vinegar in from twenty-four to thirty-six hours. Of the Lactic or Viscous Fermentation. 5961. This has only of late been treated as a distinct process, although its effects have long been known to those engaged in the manufacture of sugar and fermented liquors, whether for distillation or drink. The ropi- ness in beer, ale, or porter, the premature acidity of the distiller's wash, are referrible to the process under consideration. It is this fermentation which supervenes in the absence of yeast, or whenever any nitrogenized substance, oxidized by the air to a certain extent, is present. It differs from the vinous, in giving rise to lactic acid, mannite, and a viscous matter, usually called ropy, with hydrogen, as well as carbonic acid. Many years since I was surprised to find the gas given out by cider in a state of intense fermentation, take fire, and discovered, on examination, the inflammable gas to be hydrogen. 5962. Agreeably to a statement given in Graham, 803, an atom of man- OF FERMENTATION. 599 nite, and an atom of lactic acid, are equal to one atom of grape sugar, minus an atom of oxygen. 5963. I am under the impression that all the four fermentations may ensue either successively, or, to a certain degree, simultaneously. Thus, either starch or lactin may be converted into grape sugar. This product may be partially changed into alcohol, and in part into lactic acid and mannite (4074); while a portion of alcohol simultaneously generated, may be undergoing acetification. 5964. Each fermentation has its appropriate ferment. Thus diastase incites the saccharine fermentation, yeast the alcoholic, oxidized diastase, caseine or curd, the lactic; while the scum or sediment, called mother of vinegar, promotes the acetic fermentation. It is the obje*ct of the vintner, the brewer, and distiller, to permit only the two first fermentations, the al- coholic especially, to which the saccharine is accessary. This object is secured by taking great care to have the juice or wort simultaneously sub- jected to a temperature between 60 and 70, and a limited exposure to air, with the addition of the proper ferment, where this is necessary ; while, by great cleanliness, the presence of any matter capable of inducing the ace- tous or lactic fermentation is avoided. Much liquor is spoiled by the sub- stitution of the viscous for the alcoholic fermentation. 5965. In a memoir published in the Annales de Chymie, 3d series, 2d Vol. 257, Messrs. Boutron and Fremy have made some interesting obser- vations respecting the generation of lactic acid in milk. Oxidized caseine (5123) is considered by them as pre-eminent in efficacy as a ferment, for the lactic fermentation, by acting on the sugar of milk or lactin ; but in consequence of an affinity for the generated acid, the oxidized caseine forms with it an inert compound which precipitates. 5966. The generation of lactic acid requires the presence both of lactin and free oxidized casein. Of course, in order to increase the production of the acid, it was found necessary to add an additional quantity of lactin to milk, but to renew the efficiency of caseine, it was found sufficient to satu- rate the lactic acid as often as the production of this acid was arrested by the precipitation of the oxidized casein. 5967. Diastase, after being exposed a few days to the air, becomes ca- pable of inducing the viscous or lactic fermentation. The membranes of the stomach of a dog or calf, or the substance of a bladder, by a like ex- posure, were found capable of inciting the fermentation in question. Yet animal matters, in appearance similarly prepared, are productive of different results, as respects the proportions of mannite, of viscous matter, of lactic acid, or alcohol, generated. The means by which the various ferments, respectively, produce their appropriate changes are involved in the greatest obscurity. Some important additions have been made to our knowledge, as respects the facts. The ferments have all been shown to be vegeto-animal matter in a state of oxidizement, and an analogy seems to have been esta- blished between their influence and that of some other agents, which have been considered as acting by what has been called catalysis, which is a new name given by Berzelius to an old mystery. It has long been known that there are two modes by which chemical changes are to be excited. In one of these, the presentation of one or two extraneous elements causes de- composition and recom position, by the reactions between the elements so presented, and those subjected to alteration, as in the various cases of elec- tive affinity (508, &c.). In the other mode, substances undergo transfor- mations by being made to rearrange their constituents into one or more new 600 ORGANIC CHEMISTRY. combinations, by the presence of other bodies with which they do not com- bine, and which, in some cases, undergo no change themselves. It is to the last mentioned mode of reaction that the name above mentioned has been applied. Yet, under this head, processes have been crudely associated which have discordant features. Liebig indiscriminately gives a common explanation to these processes, and to those of fermentation, so far as they might be crudely referrible to catalysis. 5968. The following processes are associated by this distinguished che- mist under one rationale : the solubility acquired by platina by being al- loyed with silver: the catalyzing influence of platina sponge or platina black : the explosion of fulminating powders by slight causes : the reci- procal decomposition of bioxide of hydrogen and oxide of silver: the agency of nitric oxide in the generation of sulphuric acid : the action of ferments. 5969. To me it seems that there is a great diversity in the characteris- tics of the processes thus alluded to. In the case of the platina alloy there is at least an atom of silver for each atom of platina in actual combination with this metal ; and the change which the latter undergoes is precisely the same as that to which the former is subjected. 5970. In the case of platina sponge causing the formation of water, or of platina black, causing the acetification of alcoholic vapour, the inducing agent undergoes no change itself; and it enters not into chemical combi- nation either with the materials, or the products. Liebig ascribes the re- sult in this instance to the alternate absorption and subsequent evolution of oxygen by the powder; since, after exposure to the gas, it may, by ex- haustion, be made to give up a portion. But the agency of this metallic mass cannot differ, in this case, from that in which it causes the pure ele- ments of water to combine, and in which, if absorption take place, it is not confined to oxygen more than to hydrogen. But the fact established by Faraday, that hydrogen and oxygen may be made to unite by a well clean- ed plate of platina, seems irreconcilable with the idea that absorption is the mean of its accomplishment. But if absorption be not operative in one case, how can it operate in the other? 5971. In this, as in all other cases, Liebig seems to overlook the all important agency of electricity in the phenomena of nature. I should infer, that the metal most probably acts by altering the electrical po- larity, and consequent association of imponderable matter. But having assumed, that during the dehydrogenation of alcohol by atmospheric oxy- gen in the presence of platina black, this powder is alternately endowed with the power to take it from the air, and to impart it to that, of which the attraction for oxygen, under the circumstances, is too feeble to take it from the same source, this distinguished philosopher proceeds to make the inference that honey, mother of vinegar, and other substances pro- motive of acetification, act in the same way by absorbing oxygen from the air, and abandoning it to hydrogen. But if agreeably to the view above presented, platina black does not act by absorption, no argument, founded on the agency of that substance, will justify the idea that absorption avails in other cases ; and it should be recollected, that platina black is very active when perfectly free from moisture, while honey, yeast, mother of vinegar, and other substances which cause acetification, have no attraction for oxy- gen in the absence of water : moreover, that the necessity for moisture to the preparatory oxidizement of gluten, caseine, diastase, and other organic substances, which by exposure in a humid state acquire their capacity to OF FERMENTATION. 601 act as ferments, is inexplicable. Water is powerful both as a catalyzer and as a solvent. 5972. Before referring to the absorption of oxygen by honey, as a ground of explanation founded on the analogy of platina black, the ability of water to cause honey to absorb oxygen should be first elucidated. 5973. An electric spark or any ignited body, a wire made incandescent by a galvanic discharge, has an influence analogous to platina sponge, of which the minutest particle is sufficient to cause ignition throughout an in- flammable mixture, however large. There is, in this respect, an analogy between the explosion of inflammable gaseous mixtures and those of gun- powder, and of other fulminating powders, of which some, as it is well known, detonate by percussion or friction, or any cause adequate to derange the equilibrium of their particles. In the cases last mentioned, the change produced is the same, whatever may be the exciting cause, and the mi- nutest portion of the congeries being made to undergo the change, is of itself competent to produce a like result as respects the whole. 5974. The property which bioxide of hydrogen, and the oxide of silver, or bioxide of lead, have, of undergoing an explosive deoxidizement in con- sequence of mere superficial contact, is evidently another case, since the re- action is reciprocal. In the solution of the alloy of platina with silver, one body induces another to undergo the oxidizement to which it is itself sub- jected. In the case of the bioxide of hydrogen and oxide of silver, two bodies, both prone to deoxidizement, reciprocally induce that species of change. But in this phenomena there is no third body to perform a part analogous to that of the nitric acid. 5975. In case of ferments there is not only the power to produce a change, but also to produce the particular changes by which sugar, alcohol, and acetic or lactic acid, and mannite, are respectively generated. More- over, these bodies are themselves undergoing an oxidation or decomposition which is necessary to their power; but this change is not like that which they induce. Hence, obviously, they operate differently, either from the platina sponge, or platina black, or from the silver in the alloy formed by it with platina. Liebig conceives, that this increased solubility of platina by union with silver, is at war with electro-chemical principles, agreeably to which, any metal in contact with another metal, relatively electro- positive, becomes less susceptible of attack. But this is not alleged of two metals in chemical combination, but of masses in contact, or having a metallic conductor extending from one to the other. I am surprised that Liebig should find the mystery of catalysis lessened by the solution of the alloy alluded to, when it must be evident that if the oxidation of one atom were a sufficient reason why another atom combined with it should be oxi- dized, an alloy of gold with silver ought to be soluble. Whereas, it is known that the common process of parting is founded on the utter insolu- bility of gold when so alloyed. 5976. Liebig alleges that there can be no doubt that the acidification of alcohol is of the same order as the reaction by which nitric oxide provokes the formation of sulphuric acid in the leaden chamber (1019), in which process the oxygen of the air is transferred to sulphurous acid by the in- tervention of the bioxide of nitrogen, since, in like manner organic sub- stances associated with spirit of wine, absorb oxygen, and bring it into a particular state which renders it liable to be absorbed. 5977. But in the case thus cited, for every equivalent of acid formed, an equivalent of the bioxide combines first with an equivalent of oxygen, and 602 ORGANIC CHEMISTRY. in the next place with an equivalent of the sulphurous acid, forming a com- pound which is decomposed by water into sulphuric acid and the regenerated Dioxide. There appears to me to be no analogy between this process and that of the influence of matter existing in no equivalent proportion, and which cannot be shown to form a definite chemical compound, either with acetyl or hydrogen. It is not represented that, in the vinous fermentation, any union, either transient or permanent, takes place between the elements of the sugar and those of the ferment : on the contrary it is alleged, that the oxidation and precipitation of the yeast proceeds, pari passu, with the alcoholification. 5978. As to all the processes referred to for illustration, as well as those of fermentation, which they are alleged to resemble, it appears to me that Liebig and his disciples have been too sanguine of their capacity to give adequate elucidation. 5979. Respecting changes of the kind above described as catalytic, Dr. Kane uses the following language: "The elements of a compound are re- tained together in certain molecular arrangement, because the affinities are there satisfied; but it is natural to suppose that whilst the elements remain the same, their affinities for each other might be just as completely satisfied by a different molecular arrangement." This language might be held more reasonably, were this variation in arrangement accompanied by no concomitant acquisition of chemical properties; but is it reasonable to consider the difference between sugar, and the alcohol and carbonic acid into which it is resolvable, as arising merely from molecular arrangement? Can the active influence of alcohol upon the animal nerves be due merely to the situations respectively occupied by its three ultimate ponderable ele- ments, carbon, hydrogen, and oxygen, of which it consists? Admitting that the union of oxygen with the ingredients of gluten could, by imparting any consequent mechanical impulses, cause the hydrogen and oxygen of an atom of water to unite with the elements of sugar, and to separate into alco- hol and carbonic acid as above mentioned, how can that movement, or the consequent rearrangement of the ponderable particles, explain the acqui- sition of new properties, of which the combining atoms, or the compounds previously containing them, were destitute? That the presence of yeast in- duces the fermentation of alcohol, and that diastase determines the genera- tion of sugar, is admitted; but I am surprised that any philosopher should conceive, that without first ascertaining upon what the difference of the pro- perties of alcohol and sugar is dependent, we can understand how that dif- ference is caused. Liebig infers that a body in the act of decomposition or combination, may communicate a movement to the atoms of an adjoining compound, so that gluten in the state of oxidation, in which it is called yeast, induces sugar, C 13 H 11 O 11 , existing in the same liquid, to unite with the elements of water, making C 13 K 13 O 13 , separating into four equivalents of carbonic acid and two of alcohol. 5980. Adopting the same views as Liebig, Dr. Kane alleges " that the slow decomposition of diastase communicates to the molecules of many thousand times its weight of starch, the degree of motion necessary for their rearrangement, and the appropriation of the elements of water requi- site for the formation of starch sugar." 5981. It is perfectly evident, that the particles of the catalyzed substance are in some way so affected by the catalyzing body as to be put into a state of reaction, which had not otherwise ensued ; but that this is accomplished merely by imparted motion appears to me to be a surmise destitute of plau- OF FERMENTATION. 603 sibility. The fact that the weight of the diastase requisite to saccharify starch is so very small, as is alleged by Dr. Kane, evidently renders it ex- tremely improbable that it acts by creating any mechanical disturbance. Yet this respectable chemist is so completely carried away by this idea, that he proceeds to make the following remark: " This law, of which the simplest expression is that where two chemical substances are in contact, any motion occurring among the particles of the one may be communicated to the other, is of a more purely mechanical nature than any other princi- ple yet received in chemistry; and when more definitely established by succeeding researches, may be the basis of a dynamic theory in chemistry, as the law of equivalents and multiple combination expresses the statical condition of bodies which unite by chemical force " 5982. I perfectly agree in opinion with the author of these suggestions, as to the purity of the mechanical attributes of the principle on which they are founded, but cannot on this very account deem them competent to ex- plain the phenomena on which he conceives them to bear. 5983. As the mechanical influence of the motion of bodies is as the weight multiplied by the velocity, is it conceivable that any movement in the particles of one part, by weight, of diastase, can be productive of ana- logous movements in two thousand parts of starch ? 5984. The idea that yeast might owe its power to animalcules, suggested itself to me more than thirty years ago, and seems to have some support from the fact, that fermentation only thrives within the range of tempera- ture compatible with animal life. Latterly, its activity has been ascribed to the power of extremely minute vegetables. Kane, while admitting the existence in yeast of a vast number of globular bodies, possibly animal- cules, treats the idea as untenable, because the weight of the alcohol and carbonic acid is greater than that of the sugar employed. But if the union of water with the elements of the sugar, can add to the weight of the products, without the assistance of animalcules, wherefore should their agency be inconsistent with an augmentation from the same source? But the weight of the alcohol and carbonic acid are just equal to that of the sugar, if this be assumed to be in the state of sugar of grapes (5578). 5985. Independently of any agency of this kind, which seems even more probable in the case of some species of infection, than in that of fer- mentation, I conceive that the present state of our knowledge does not allow of our comprehending the means by which bodies, whether organic or inor- ganic, are endowed with the powers ascribed to catalysis ; but that we have great reason to believe that these powers, as well as all the properties which ultimate elements acquire by diversity of association, as in compound radi- cals, are due to the same source as the phenomena of galvanic and statical electricity. 5986. It is well known, that although pure zinc is not susceptible of oxi- dation by exposure to dilute sulphuric acid, yet that, when containing mi- nute proportions of other metals, as in the case of commercial zinc, it be- comes liable to rapid oxidation by the same reagent. This Faraday ex- plained by the electro-chemical influence of the comparatively electro-nega- tive metallic particles distributed throughout the mass of the zinc, which he conceived to be productive of as many local galvanic circuits with corres- ponding currents. This explanation has, I believe, been universally sanc- tioned, and was consistent with the previous discovery of Sturgeon, that when, by amalgamating the surface with mercury, a metallic communica- 77 604 ORGANIC CHEMISTRY. tion was made between the electro-positive and electro-negative metallic particles, so as to prevent the formation of electrolytic currents through the oxidizing liquid, the zinc became nearly as insusceptible of union with oxy- gen, as when in a pure state. 5987. Nevertheless, either when pure, or when amalgamated, the zinc was found oxidizable by diluted sulphuric acid, provided it were made the element of a galvanic pair. 5988. The facts above mentioned having been recalled to the attention of the scientific reader, I beg leave to inquire whether the influence thus as- cribed by Faraday to the electro-negative metallic particles has not a greater analogy with that of a ferment, than those which have been brought for- ward by Liebig, Kane, and others, with a view to explain the influence of that class of agents upon mechanical and chemical principles'? Wherefore may not the distribution of nitrogenated substances throughout a mass of inorganic matter, operate as do the metallic impurities in commercial zinc? The existence of a powerful voltaic series in the gymnotus and other elec- trical fishes, shows that the substances which enter into the composition of animal matter are, when duly associated, as capable as metals of forming the elements not only of simple, but of complex galvanic circuits. OF THE PUTREFACTIVE FERMENTATION. 5989. To that species of spontaneous decomposition which is called pu- trefactive, animal substances, in general, are much more disposed than ve- getable; and the effluvia which they emit, during the change, are much more offensive. It seems as if certain affinities which exist between the ultimate elements of many vegetable and animal substances, although sus- pended by the inexplicable powers of vitality, resume their operation as soon as those powers cease, with greater or less activity, according to the nature of the substance, and the influence of heat and moisture. 5990. The presence of phosphorus and sulphur contributes greatly to the fetor of animal putrefaction. On the other hand, few animal substances are susceptible of the vinous or acetous fermentation. 5991. Liebig seems disposed to obliterate the line which was heretofore drawn between fermentation proper, and putrefaction. He alleges, that in practice the principal mean of discrimination has been the diversity of odour. To fermentation has been ascribed all processes attended by trans- formations, resulting from internal reaction, which are attended by no un- pleasant smell ; whereas fetid processes, in other respects analogous, have been designated as putrefactive : but that, in point of fact, the presence of nitrogen seems to have been the usual associate of substances prone to what is called putrefaction. 5992. But so far as fetidity is an essential attribute of putrefaction, the presence of hydrogen, with sulphur and phosphorus, seems to me more es- sential than that of nitrogen, since this element is much more rarely the vehicle of fetid emanations, and, when isolated, is remarkably inodorous. 5993. The presence of water, or of its elements, seems indispensable to the spontaneous decomposition of organic substances. In no instance is either the vinous, acetous, or putrefactive fermentation induced, in sub- stances which are perfectly dry. The effect of desiccation in preserving meat and fruits, sufficiently proves the correctness of this allegation. It is, probably, by paralyzing the activity of the water in meat, that salt favours OF THE PUTREFACTIVE FERMENTATION. 605 its preservation ; and the beneficial influence of sugar upon preserves may in like manner be explained. 5994. The peculiar efficacy of water in promoting fermentation, of \vl at- ever kind it may be, rests, as I conceive, on the same basis as its peculiar efficiency in promoting electrolysis. And until we are capable of compie- hending the part it performs in the one case, we shall vainly endeavour to understand the duty which it fulfils in the other. 5995. When, in addition to water, nitrogen is a constituent, the tendency to decomposition is increased. Gluten and yeast, which contain nitrogen, are very liable to an extremely offensive putrefaction. To their deficiency in this principle, Dr. Turner ascribes the indisposition of oils to putrescency ; but I conceive their freedom from water, and incapacity to unite with it, to be the true cause. 5996. The insusceptibility of the vegetable alkalies to decomposition, while containing both hydrogen, oxygen, and nitrogen, may arise partly from their sparing solubility in water, and partly from the predominance of carbon in their composition (5506). 5997. Although heat, to a certain extent, is necessary to putrefaction, it may be arrested by a high temperature, as well as by frost. In the one case, water, being vaporized, is removed ; in the other, being congealed, be- comes inert. 5998. Thenard alleges that water is not decomposed during putrefaction, but, on the contrary, generated. 5999. Besides water, we may enumerate ammonia, with carbonic, acetic, and sulphydric acid, also carburetted and in some cases phosphuretted hy- drogen, among the products of putrefaction. INDEX THAT PORTION OF THIS COMPENDIUM WHICH RELATES TO INORGANIC CHEMISTRY. Absorption of aeriform fluids, 222 by charcoal, 223 of heat, 6 of light, 79 of nitric oxide, 183 produces heat, 6, 223 by silk and woollen stuffs, 223. Acetate of ammonia, 5 of baryta, 276 of copper, 314 of lead, 90, 318 of zinc, 332. Acetates in general, 459.* Acid, acetic, 314, 318* alumina acts as an, 268 antimonic, 346 antimonious, 346 arsenic, 335, 336* arsenious, 91, 335, 336 auric, trioxide of gold, 291 benzoic, 329 boric, 250 bromic, 129 carbonic, 225, 229 chloriodic, 133 chloric, 126 chlorohydric, 141, 157, 162, 163 strength of, 164 chlorous, 123, 124, 125 chloroplatinic, 294 chloroplatinous,294 chloroxycarbonic, 233* chloroplatinic and chloroplati- nous,282 chromic, 353 croconic,232* cyanhydric, 153, 246, 278, 367* cy- anic, 243* cyanoferric, 243 cyanofer- rous, 243, 246 cyanuric, 243* denned, 357 dephlogisticated marine (i. e. chlo- rine), 117 fluoboric, 258 fluohydric, 134, 256 fluosilicic, 134, 251, 257 fluohydroboric, 257 fluohydrosilicic, 257 fulminic, 243* hydrochloric, 160, 162, 163, 285 hydrofluoric, 256 hy- drous cyanic, 244 hyperiodic, 133 hypochlorous, 123, 362 hyponitrous, 183 hyposulphuric, 1 37 hy posulphu. rous, 137 iodic, 131, 133 iodohydric, 131, 159, 165 iodous, 133 manganic, 354 margaric, 202* mellitic, 232 muriatic or chlorohydric, 160 nitric, 190, 191 nitro-muriatic (aqua regia,) 291,292 nitrous, 184 nitrosonitric,213 oxalic, 231* oxy, or per, manganic, 354 oxymuriatic,119t perchloric, 127 phosphoric, 216 phosphorous, 216 * See Index to Organic Chemistry. t See Emendation, end of Index, page xix- prussic (cyanhydric), 246, 248* selen- hydric, 171 selenic, 141, 142 sele- nious, 141, 142 silicic, 253 stearic, 202 succinic, 329 sulphydric, 166, 168* sulphocarbonic, 234 sulphocy- anhydric, 245 sulphuric, 139, 140 sulphurous, 137 tartaric, 346* tellu- hydric, 171 tungstic, 355. Acidifiable metals, 261. Acidity, 201. Acids, amphydric, 304 halohydric, 159, 304 organic, 109* relation to positive pole, 109 with mercury, 304 reaction of, with litmus, 203. Action, mechanical, of the lungs, 29. Aeriform or elastic fluids, 105. Aerolites, 324. Affinity, simple and double elective, or complex, 89, 90. Agency of water, 151.* Aggregation, attraction of, 83. Air, 11, 18, 19, 22, 23, 24, 28, 41, 103, 154, 174 cold and cloudiness consequent to rarefaction of, 37 condensation of, 27 elastic reaction of, 22 pump, 21, 24 rarefaction of, 23 weight of, 14. 104. Alcohol, 101, 239.* Alloys, 263. Alkalies, fixed, 278, 288 organic, 109.* Alkanet, as a test for alkalies, 203.t Alkaline earths, 270, 271. Alum, 264, 266. Alumina, 267 hydrate of, 266, 267. Aluminate of magnesia, of zinc, 265. Aluminium, 268. Amalgams, 301. Amalgam of ammonium, 209. t Amalgam of gold, 290 of potassium, so- dium, 208, 209. Amalgams of calcium, barium, strontium 272. t * See Index to Organic Chemistry. t See Index to Electricity. 11 INDEX. Amethyst, 265. Ammonia, 90, 92, 205, 206, 207* reac- tion with oxide of silver, or that of cop- per, 90 nitrate of, 180. Ammoriiacal nitrate of copper, 91 of sil- ver, 91. Ammonium, 208 chloride of, 209 reac- tion of chloride with lime, 92. Amphigen bodies, 108. Analysis of gaseous mixtures, eudiometer for, 185, 228 volumescope, Volta's eu- diometer for, 148 of olefiant gas, 238. Animal charcoal, 222* respiration, 227* substances, 370.* Anhydrous antimonic acid, 346 sulphu- ric acid, 139.* Annealing, 254, 255, 263. Anode, 197. t Anthracite, 220. Antimony, 89, 344 bichloride of, 347 bisulphide of, 349 crocus of, 348 glass of, 348 golden sulphur of, 348 liver of, 348 oxysulphide and hydrated oxysulphide of (kermes mineral), 348 precipitated sulphide, 348 perchloride of, 347 regulus of, 344 selenide of, 349 sesquichloride, 347 sesquioxide, 345, 347, 349 sesquisulphide, 347, 348 sulphide, 348. Aqua ammonite, 208. Aqua marina, 269. Aqua regia, 291. Aqueous vapour, 31 to 41 ; 151 to 155. Arbor Dianse, SO Saturni, 86. Argand lamp, 65. Argentine flowers of antimony, 345. Aridity of the air, 155. Arsenic, 334 compounds of, 338* means of detecting, 340 poisoning by, 340 selenides of, 339 sulphides of, 338 reactions of, 338, 339. Arseniates and arsenites, 337. Assay furnace, 299. Athermane and diathermane bodies, 56. Atmosphere, 19, 174; see^r eudiometer for analysis of, 214. Atomic theory, weights, 95, 96, 97. Attraction, 2, 83, 88. Attrition, ignition by, 61. Aurate of ammonia, 291. Avena sensitiva, hygrometer by, 39. Azote (nitrogen), 172.* Barium, 271, 272, 276 process for evolu- tion of, 272. t Barometer and barometric column, expla- nation of, 14 to 26. Barometer gauge, 26. Baryta, or barytes, 275, 276. Basacigen elements, 108, 261. Basidity, 109. Basifiable metals, 261. Base metals, 260. Bellows, of and forge fires, 65. Benzoic acid, 329. Benzoate of lead, 317. * See Index to Organic Chemistry, t See Index to Electricity. Berzelius. See letter from. Biborate of soda, 249, 367. Bibromide of mercury, 307. Bicarburet of hydrogen, 235, 240. Bicarburet of nitrogen or cyanogen, 241.* Bichloride of antimony, 345. Bichlorine ether, or chlorohydrate of chlo- ride of acetyl, 233, 241* Bichloride of mercury, 301, 306. Bichromate of lead, 317. Bicyanide of mercury, 241, 246, 308. Bihydroguret of carbon (fire damp), 236. Biiodide of lead, 319. Biiodide of mercury, 307. Binary salts, 358. Bioxalate of potash, 231. Bioxide of lead, 316. Bioxide of manganese, 354. Bioxide, 136. Bioxide of barium, 276. Bioxide of calcium, 275. Bioxide of hydrogen, 156 of mercury. 301 of tin, 320. Biphosphates, 367. Bismuth, 322, 323. Bisulphide of antimony, 345 of bismuth, 324 of carbon, 234 of iron, 325 of mercury, 301. Bitartrate of potash, 281, 369. Bitter almonds, oil of.* Bitumen, 220. Bituminous coal, 220. Black oxide of copper, 312 of iron, 325 of manganese, 354 of mercury, 302. Bleaching, 119,361. Bleaching salt, 172, 361. Blende, 331. Blowpipe, 65. Blowpipe, compound, or hydro-oxygen, 66. Blue stone, or blue vitriol (sulphate of copper), 313. Boiling point, 31 to 37, 52. Bone, or ivory black, 221. Borates, 367. Borax, 367. Boron, 249, 250. Boruretted hydrogen, 284. Boruret of potassium, 284. Brass, 89, 263. Brazil wood, test for alkalinity, 203. Bromide of carbon, 233 of cyanogen, 245 of iodine, 133 of mercury, 304 of selenium, 142 of silver, 299 of sul- phur, 140. Bromine, 128 in mineral springs, 129. Bronze, 89. Cadmium, 352. Calamine (silicate or carbonate of zinc), 331. Calcia, or lime, 273 alkalinity of, 203. Calcination, 274. Calcium, 272, 300 apparatus for evolu- tion of, 272. Caloric, 3, 5, 14, 74, 263. Calomel, 304. * See Index to Organic Chemistry. INDEX, 111 Calori motor.! Cannel coal, 221).* Caoutchouc, 239.* Carbohydrogen, 235, 240, 241.* Carbon, 220. Carbonates, 367. Carbonate of cadmium, 352 of lead, 277, 317, 318 of lime, 274 of magnesia, 271 of zinc, 331. Carbonic acid, liquid, solid, 225, 226, 229, 230. Carbonic oxide, 224.t Carburets of potassium, 283. Cast steel, 325. Cathode, 197.t Cementation of iron, 325. Cerium, 262. Ceruse, 277, 319. Chalybeate springs, 326. Chameleon mineral, 354. Charcoal, 220, 221,223. Chemical affinity, 83, 88 attraction, 83 equivalents, 94 implement, 21 reac- tion, 2. Chemical symbols, 96. Chemistry, definition of, 1. Chloracid, 268. t Chloral, 232.t Chlorate, 362. Chlorate of potash, 361. 363. Chloride, 122, 285. Chloride of aluminum, 268 ammonium, 209 boron, 251 bromine, 130 of glu- cinium, yttrium, thorium, 285 gold, 292 hydrogen, 160 iodine, 133 iron, 329 mercury. 304 of lithium, deli- quescence, solubility of, in alcohol, 284 of nitrogen, 128 phosphorus. 121, 217 potassium, 127 selenium, 142 silicon, 254 silver, 299 sulphur, 140 thorium, 270, 285 yttrium, 285. Chlorides of carbon, 233 of sulphur, 140. Chlorine, 108, 117, 119, 157, 241 hydrate of, 156. Chlorite or hypochlorite of lime, 172. Chlorobases, 200. Chlorohydrate of the chlorobase of cop- per, 314. Chlorosalts, 370. Chlorohydrates, 285. Chromates, 319. Chromium, 350. Cinnabar, 300. Cisterns, hydropneumatic, 105, 106. Classes of metals, 260. Classification, 108, 109, 110, 198. See let- ter on Berzelian nomenclature. &>c. Clay, 266. Cobalt, 251, 354. Cohesion, 83, 91. Coke, 220. Cold, 27, 62, 68, 73 by combination, 73 by vaporization, 60 radiation of, 50, 55. Colouring matter of the blood, 245.* Colours, different rays, 78, 79. Columbium, 354. * See Index to Organic Chemistry, f See Index tn Electricity. Cork, 239 to ascertain specific gravity of, 100. Combustibles, foundation of idea of, 198. Combination, Cl, 91. Combustion, 113, 118, 136, 194, 251, 310. Complex or double elective affinity, 90. Compound, or hydro-oxygen, blowpipe, 66. Concave mirrors, 53. Condensation, 27 to 30. Condensation of gases by charcoal, 222 for illumination, 240. Condenser, 27. Congelation of water, 67 to 73 of car- bonic acid, 229 of prussic acid, 248 of sulphur, bismuth, antimony, zinc, 86. Copper, 310, 311,312. Corindon Telesie, 265. Corrosive sublimate, 305. Croconate of potash, 232. Crocus of antimony, 348. Cryophorus, 71, 72. Crystallization, 83, 84. Crystallized potash, 282. Crystallography, 84. Crystals of Venus, 314. Cubic galena, 141. Cuprum ammoniatum, 313. Cupel and cupellation, 297. Culinary paradox, 32. Cyanates, 368. Cyanide, or bicyanide, of mercury, 241, Cyanide, cyanure, or cyanuret, of potas- sium, 370 silver. 299 zinc, 333 iron, 242. Cyanobases, 200. Cyanoferrate of potassium, 243. Cyanoferrite qf potassium, 243, 247. Cyanogen, 108, 157, 241, 242. Cyano salts, 370. Cyanures, cyanurets, or cyanides, 287,370. Dalton on vapour, 40. Damask steel, 325. Daniell's blow-pipe, erroneously so called, 67. Decayed wood, light from, 76. Decoloration by charcoal, 222 by proto- chloride of tin, 322. Decomposition of ammonia, 207 of water, 152. Decrystallization, 87. Definite proportions, 83, 93. Dephlogisticaled marine acid, (chlorine,) 117. Derbyshire spar, (chloride calcium,) 251, 256. Desiccation of air, means of effecting, 70 of the skin, 154. Detection of arsenic, 340. Deuto carbohydrogen, 235, 237. Deutoxidcs defined, 136. Deutoxide of hydrogen, 156. Diacetate of lead, 318. Diamond, 220. Diaspore, 266. * See Index to Organic Chemistry. IV INDEX, Diathermane, and athermane, bodies, 56 Dicarburet of hydrogen, 236. Dichloride of carbon, 233. Bichloride of copper, 314. Dioxide, disulphide of lead, 319. Differential thermometer, 13. Dilatation by heat, 9. Dioxide defined, 136. Dioxide of lead, 316. Disinfecting power of charcoal, 222. Disinfection by hypochlorites, 361, 362. Dispersion of light, 78. Disulphide of copper, 311, 315. Dolomite, 271. Double elective, or complex affinity, 90. Double oxysalts, 368. Double salts of metals, 261. Double silicates, 368. Drummond's lime light, so called, 67. Dutch gold leaf, combustion of, in chlo- rine, 119. Ductility of metals, 263. Dyeing, 267 mordants for, 267.* Dynamic electricity, 82. t Earths, 264. Ebullition, 32 by cold, 32. Effervescence, 43. Elasticity, 15 to 44. Elasticity of metals, 263. Electricity, see separate treatise on. Electro magnetism.t Electrometer and electroscope, t Electro-negative metals, 261. t Electrophorus, 58.t Electro- positive metals, 261. t Emerald, 269. Epsom salts, 89, 271,356. Equivalents, 94. Essential oils, 241.* Ether, 209.* Ether, chloric, perchloric, explosive, 128.* Etherine, 236 * Euchlorine, 124, 361. Ethiop's mineral, 300 Euclase, 269. Eudiometer, 185, 238 of Volta, 148 sli- ding rod, 175, 176, 185. Eudiometry, 148, 184, 213. Evaporation, 40, 41 by air, 41 cold pro- duced by, 41, 68 to 73. Everitt's process for cyanhydric acid, 247. Evolution of iodine, Exception to the law that chemical reac- tion requires fluidity, 92. Exceptions to the law that liquids expand by heat, 9. Exhaustion, 43. Expansion of fluids, 10,30 liquids, 8 so- lids, 6 supposed exception to the, 7 theory of, 31 water, 9. Explosive power of steam, 37. Extreme pressure, vaporization of liquids under, 37. Explosion of fulminating mercury, 5 by high steam, 37 mechanical action in- ducing decomposition, 62 of chlorous * See Index to Organic Chemistry, t See Index to Electricity. acid, euchlorine, 126 oxychlorate of ethyl, 128* chlorine with hydrogen, 160 hydrogen with oxygen, 148 ok- fiant gas with oxygen, 239. False copper. Kupfer nickel, 351. Feldspar, 268, 357. Ferri et potassae tart, 368. Ferroprussiate, or cyanate of potash, cy- anoferrite of potassium, 242. Ferruginous minerals, 324. Fffitid or feculent emanations neutralized, 224, 360. Filters of charcoal, &c., 222. Finery, cinder, 328. Fire damp, 235. Flame, 162 of hydrogen, 146 reddened by strontia, 277. Flowers of sulphur, 135 antimony, 345 zinc, 331. Fluids, ae'riform, 10, 14 to 44, 105. See Gases. Fluoride of arsenic, 338 bismuth, 324 calcium, 212, 256 chromium, 353 bo- ron, 134, 255 silicon, 255 lead, 319 mercury, 308 silver, 299 zinc, 333, Fluorides, 370.t Fluosalts, 370.t Fluoborate of hydrogen, 258.t Fluocolumbate of potassium, 354. Fluohydrate of potassium, 258.t Fluoglucinate of potassium, 269. Fluorine, 108, 134, 157, 252. Fluorine acids, or fluacids, 157. Fluosilicate of hydrogen, 370.t Fluothorate of potassium, 270. Flux, black, white, crude, 322* Forge fires, 65. Fossil coal, 220.* Fowler's solution, 337. Freezing of mercury, 71, 230 mixtures, 73, 230 water, 68, 73. French alum, 266. Friction, ignition by, 60. Frigorific mixtures, 73. Fulminates, 368. Fulminating gold, 206 mercury, 303 silver, 206. Fulminate of mercury, 368. Fusible carburet of iron, (cast iron,) 325. Fusion of platina, 68. Gadolinite, 269. Gahnite, 265. Galena, 141, 315. Galena argentiferous, 297. Galvanism.! Gases, table of specific gravities of, 104 of equivalent weights and volumes, 189. Gaseous ammonia, 205 chlorohydric acid, 162 sulphydric acid, 166 sulphuric acid, 139. Gaseous mixtures, eudiometrical analysis of, 148, 175, 185, 224 influence of pla- tina on, 296. * See Index to Organic Chemistry. f See Essays and Letters on Nomenclature. J See Index to Electricity. INDEX, Gas lighting, 239. Gasometers, 106, 107. Gay Lussac on volumes, 107. German silver, (packfong,) 352. Gibbsite, 266. Gilding, 290.t Glass, 251, 254,297,368. Glass formed by fused borax, 251. Glauber salt, 88, 89, 356. Glucina, 268, 269. Glucina fluacid of, 269. Glucinium, 268. Gold, 290. Golden sulphur of antimony, 348. Gold and silver coin, 263. Goniometer, 85. Goulard's extract, 318. Gravimeter, 102. Gravity, specific, 100, 102, 103. Green vitriol, 326. Gypsum, 85, 357. Hematite, 141. Halogen bodies, or elements, 108, 202. Haloid salts, 356. Hardening metals by refrigeration by the hammer, 263. Heat, 47, 48, 49, 62, 64 capacities for, 44 by condensation, 63 for chemical purposes, 64 latent, 4 by solution, 62 radiation of, 52 specific, 44. Hexacarbohydrogen, 236, 240. Hexacetateoflead, 318. High pressure boiler, 35. High steam, 35. Homogeneous attraction, 83. Honystone, 322. Hydracids, 157. See Jlcids, halohydric. Hydrargyrum precipitatum album, 309 amido bichloride of mercury.* Hydrate, 151. Hydrate of alumina, 266, 267 of carbon,* 220 of chloral, 232 of chlorine,* 156 of lime, 274. Hydrate of lithia, 284 of potash, 136, 280 of soda, 281. Hydrated bioxide of tin, 320 dioxide of copper, 314 protosulphide of iron, 330 subnitrate of bismuth, 322. Hydric ether, oxide of ethyl, 238, 273.* Hydrogen, 143, 156, 160, 206.* Hydrogen, polysulphide of, 170. Hydrometers, 101. Hydropneumatic cisterns, 105. Hydrosublimate, Howard's, 305. Hydrous protochloride of iron, 329. Hygrometer of Daniell, 155. Hygrometers, 39. Hygrometic process of Dalton, by the dew- point, 155. Hypochlorite of lime, 361. Hyponitrites, 365. Hyponitrous ether, 238.* Hyposulphates, 366. Hyposulphites, 366. * See Index to Organic Chemitry. t See Index to Electricity. Ice, 10,70, 71,74, 163. Ignition, galvanic, 58, 59. Illustration of equivalents, 95. Implement, chemical, 21. Imponderable substances, 3. Indigo, 202.* Influence of air on apparent weight of bodies, 103. Influence of pressure on the bulk of air, 28. Influence of solution on chemical reac- tion, 92. Infusions, hygrometer for, 101. Ink, 329.* ' Inorganic chemistry commenced, arrange- ment of, in treating, 107. Inorganic substances, 107. Insects, light evolved by, 76. Insoluble chlorides, pretensions to the sa- line character, 356. Insoluble oxalates, 232. Insoluble oxides, 356. Insoluble sulphides, 366. Instrument for the inflammation of small portions of gas, 219. lodacids, 157. Iodide of arsenic, 338 bismuth, 324 cy- anogen, 245 gold, 292 iron, 330 lead, 319 mercury, 307 silver, 299 sulphur, 140 tin, 321 zinc, 333. Iodides of carbon, 233. Iodine, 108, 130,131,134,297. Iodine in sea salt, 286. lodo salts, 370. lodous acid, 133. Iridium, 293, 297, 351. Iron, 91 , 245, 324 with acids, 328 with carbon, 263 with gold, 328 wire, 181. Isomeric bodies, 217. Isomorphous substances, 84. Kermes mineral, 348. Kernels of bitter almonds, 246 * Kupfer nickel, 351. Laboratory thermometer, 12. Lakes, 267.* Lamp, Argand, 65, 235. Lamp enamellers, 66. Lamp without flame, 65. Latent caloric, 4. Laurel water, 246. Lavoisier's apparatus for recomposition of water, 153. Lead, 315 reagents by which it may be precipitated from its solutions, 317. Lead water, 318. Lepidomene, 284. Leslie's thermometer, 13. Light, 3, 75, 76", 77, 78, 79. Light, chemical effects of, 80. Light carburetted hydrogen, 236. Light, sources of, 76 polarization of, 80, 81 without caloric, 76. Lime, 92, 273, 274 with silicic acid, 275 with oxides, 275 with water, 275. Lime light, 67. * See Index to Organic Chemistry. VI INDEX, Liquefaction of carbonic acid, 229. Liquefaction of chlorohydric acid gas, 163 of cyanogen, 241 of nitrous ox- ide, 181. Liquids, caloric in, 50. Liquid chlorohydric, or muriatic acid, 163. Liquid sulphurous acid, 138. Lithia, 284. Lithium, 284. Litmus, 119,268. Liver of antimony, 348. Loss of gas by condensation, 240. Luna cornea, 299. Lunar caustic, 300. Lungs, action of, 29. Lustre of metals, 263. Magistery of bismuth, 323. Magnesia, 270. Magnesite, 271. Magnesium, 270. Magnesiferous alumina, 267. Magnetic influence of nickel, 351. Magnetic oxide of iron, 328. Malateoflead, 317. Malleability of metals, 263. Malleable iron, 325. Manganese, 138, 354. Manganic acid, 354. Manufacture of oil of vitriol, 193. Marble, 273, 357. Margaric acid, 202.* Marsh's apparatus, 343. Matter, 1,3. Massicot, 316. Maugham's blowpipe, so called, 68. Mechanical division, 223. Mechanico-chemical agency of charcoal, 223. Media of refraction, 79. Meconate of lead, 317. Melting ice by combustion of carbon, 222. Menachanite, 355. Mercury, 91, 300, 301. Mercury, frozen, 230. Mercurial salts, 301. Mercurio-pneumatic cistern, 105. Metallic crystals, 87. Metallic oxides, 206.t Metals, 197, 262, 263. Metals of alkalies, 284. Metals of earths, 264, 284. Metals, expansion of, 6, 7. Metals proper, 261. Metameric bodies, 244. Meteorolites, 324. Meterioric iron, 324. Mineral crystals, 87. Mineral waters, 130. Minium, 316. Moisture in air, 154. Moisture in clay, 266. Molybdate of lead, 354. Molybdenum, 354. Moon, light of, 76.* * See Index to Organic Chemistry. t See Essays and Letters on Nomenclature. Mordants, 267. Mortar, 275. Muffle, 299. Muriate of ammonia, 92. Muriate of lime, 275. Mytheline, or methyl, 235* chlorohy- drate of, 235.* Naphtha, 209, 229, 283.* Naphthaline, 235, 240. Native naphtha, 241.* Native protosulphide of iron, 330. Neutral acetate of copper, 314. Neutral nitrates, 364. Neutral phosphates, 367. Newton on light, 75. Nickel, 351 spongy, 297. Nitrate of ammonia, 180 of copper, 313 of cobalt, 268 of lead, 317 of lime, 275 of silver, 299 of zinc, 332. Nitrates, 364. Nitrites, 365. Nitrogen, 172, 173, 174, 179, 283. Nitric oxide (nitrous air of Priestley), 182, 212. Nitrous oxide, 179 liquefied, 181. Nituret, or amiduret, of potassium, 283.* Nituret, or amiduret, of sodium, 283.* Nituret, or amiduret, of copper, 311. Noble metals, 260, 261. Nomenclature, 122, 136, 157, 158, 198-9. Nordhausen, sulphuric acid of, 139. Numerous compounds of carbon, 235. Obsidian, 269. Ochres, 327. Odour, alliaceous, of phosphorus, 211 of arsenic, 342. Odour of selenium, 140, 141. Oil of turpentine, 229, 238.* Oils, fixed, volatile.* Ointment, mercurial, 300. Olfactory nerves peculiarly affected by selenhydric acid, 171. Olefiant gas, hydruret of acetyl, 188, 235, 238.* Ores of zinc, 352. Organic acids, 109* alkalies, 109. Osmiate of soda, 351. Osmium, 297, 351 alloys of, 351. Osmiuret of iridium, 351. Oxacid of gold, 291.t Oxacids, 157, 158. Oxalate of copper, 232 iron, 232 lead, 317 lime, 232 magnesia, 232. Oxalis acetosella, 231 Oxibases, 258, 285. Oxidability of metals, 263. Oxide of boron, 250 bromine, 129 cad- mium, 352 calcium, 273 cobalt, 354 glucinium, 269 iridium, 351 lith- ium, 284 magnesium, 270 magnetic, 263, 328 of molybdenum, 354 nitric, 182 nitrous, 181 of osmium, 351 se- lenium, 141 silicon, 253 tellurium, 143 thorium, 270 titanium, 353, 355 yttrium, 269 zirconion, 259.t * See Index to Organic Chemistry. t See Index to Electricity. INDEX, Vll Oxides of antimony, 345 arsenic, 335, 336, 337 barium, 277 bismuth, 323 calcium, 273, 275 chlorine, 123 chro- mium, 352 copper, 312 gold, 291 hydrogen, 156 iron, 325, 326 iodine, 133 lead, 316, 317 manganese, 354 mercury, 302, 303 nickel, 352 nitro- gen, 17!) phosphorus, 215 potassium, 283 platinum, 294 silver, 298 so- dium, 283 strontium, 277 sulphur, 137 tin, 320 zinc, 331, 332. Oxybase of ammonium, 209. Oxy chlorate of potash, 127 of barytes, 281 of ethyl.* Oxychloride of antimony 345 of bis- muth, 323 of mercury, 306. Oxygen, 108, 110, 111, 112, 113, 114, 115* acids, 157. Oxygenated water, 156. Oxyhydrogen blow-pipe, 66 eudiometer, 176. Oxysalts, 359. Oxysulphide of antimony, 349 of tellu- rium, 143. Oyster shells, 274. Packfong, (German silver,) 352. Palladium, 350 alloys of, 350 sponge, 297. Palm glass, 38. Paracyanogen, 242. Paradox, culinary, 32, 33. Particles, 1. Peach leaf, 246. Pearl ash, 280. Pencil of solar light, 76. Perbromide of iodine, 133 of phosphorus, Percarburet of potassium, 283. Perchlorates, 364. Perchloride of antimony, 120, 345 of cy- anogen, 245 of iodine, 133 of phos- phorus, 217. Percussion, heat produced by, 60. Percussion powder, 368. Periodide of carbon, 233. Perkins on steam, 37. Peroxide of barium, 277 of calcium, 275 of copper, 311 of potassium, 283 of silver, 299 of sodium, 283 of stron- tium, 277 of zinc, 331. Perphosphuretted hydrogen, 218.t Persulphide of antimony, 345 of arsenic 335, 338 of lead, 319. Petalite, 284. Pewter, 263. Philosophic candle, 147. Phlogiston, 196. Piston valve volumeter, 178. Phosphate of iron, 326 of lead, 319 of liine,211 of soda, 211. Phosphates, 366, 367. See Emendation, end of Index to Organic Chemistry. Phosphites, 366. Phosphorescent wave, 76. * See Index to Organic Chemistry, t See Index to Electricity. Phosphorus, 114, 121, 181,211,213,363 combustion of, 212 crystallized, 212 ignited by radiation, 53 isomeric acids of, 217 with gold, 290. Phosphuret of arsenic, 339 of iron, 326 of zinc, 331 of potassium, 283. Phosphurets, 366. Phosphurets of mercury, 309. Phosphuretted hydrogen, 219.t Physical reaction, 1. Physiological reaction, 2. Plants require air and water, 154 absorb carbonic acid, 227.* Platinated asbestos, 297. Platinum or platina, 293, 294, 295, 297. Platinum, fusion of, 68 scroll, 296 sponge, 74, 296, 297. Plumbago, 220, 223. Plumbum corneum, 319. Pneumatic chemistry, 83. Polarization of light, 80. Poles, negative and positive, 197.* Polymeric, 235. Polysulphuret of hydrogen, 170. Pompholix, 332. Ponderable elements, 107 fluids, 104. Porcelain, 268, 207. Porosity of charcoal, 55, 223. Porous bodies, 223. Potash, 282. Potash, bichromate of, 353 bitartrate and biborate of, 369 manganate of, 354. Potassium, 162, 178, 279 chloroplatinate of, 295. Powder, bleaching, 172, 361. Precious stones, 85, 265. Precipitated sulphuret of antimony, 349. Preparation of oxygen, 111, 112 of potas- sium, 278. Pressure, 28 of the atmosphere, 14, 15, 18, 33 on fluids, 30, 31 of liquids, 32, 33 modifies boiling, 34 restrains che- mical action, 43. Prince Rupert's drops, 255. Principal character of acids, 358 groups of salts, 358.t Prism, 77, 78, 80. Proportions, definite, 93. Protobromide of iron, 133. Protochloride of arsenic, 335 bismuth, 323 carbon, 233 copper, 311, 314 cyanogen, 245 gold, 291, 292 iodine, 133 iron, 183, Io6, 325 mercury, 301 306 tin, 320, 327. Protocyanide of iron, 330 phosphuretted hydrogen, 318 selenide of copper, 315 sulphate of iron, 183, 186 sulphate of tin, 320. Protosulphide of arsenic, 335,338 copper, 311 gold, 292 iron, 325, 330 lead, 319 mercury, 301, 308 tin, 321. Protoxide of barium, 277 bismuth, 323 calcium, 273 copper, 311 iron, 325, 326 lead, 316 manganese, 354 mer- cury, 301 nickel, 352 nitrogen, 179 * See Index to Organic Chemistry, t See Emendations, p. xx. Vlll INDEX. potassium, 280 silver, 298 sodium 280 strontium, 277 tin, 320 zinc 331. Prussian blue, 330. Prussiate of potash, 330. Pulse glass, 38. Pump, air, 21 condensing, 27 exhaust- ing, 27 forcing, 27 lifting, 27 water, 19, 21. Purple powder of Cassius, 291. Pyroligneous acid, 235. Pyrometer, 6 Daniell's, 7 Wedge- wood's, 8. Pyrophorus, 112, 283. Pyroxylic spirit, 235. Quadroxide, 137. Quantity of air in a given space is as its pressure, 29. Quartz, 251, 253. Quick communication of heat, 52. Quicklime, 205, 206, 274. Radiant light, 75. Radiation of cold, 55 of heat, 55. Radiators, 54, 55. Radical of an acid or base, the combustible body in, 157. Radicals, metallic, 110, 143 non-metallic, 110, 143. Radiant heat, 52, 56. Rain storms, non-electric, 40. Rarefaction, 23, 37, 39. Rationale of frangibility of glass, 48 re- frigeration of a jet of high steam, 36 diversity of radiating power of, 54. Rays, chemical, heating, illuminating, 56,57,78. Reaction, elastic, of air,22 intense corpus- cular, 196 attractive, 2 repulsive, 2. Reaction of particles and masses of mat- ter, 1. Reaumur's scale, 12. Receiver, exhausted, 22 to 27 condensa- tion of air in, 29. Recomposition of water, 153. Red cabbage, infusion of as a test, 203. Red oxide of copper, 311 of iron, 325 of lead, 354,316 of mercury, 302. Reduction of metals, 263. Reflectors, 54. Refraction, 76, 78. Refrangibility of light, 79. Refrigeration, 73, 74 ? 234. Registering thermometer, 12. Regulus of metals, 263. Relaxation of pressure on air, or rarefac- tion of, produces cold, 38. Remarks on nomenclature, 122, 136 157, 198, 199. See Essays, letters, fyc. Repulsion, 2 repulsive influence of ca- loric, 3, 9. Reservoir for hydrogen, 144. Reservoirs, self-regulating, 226. Respiration, 29, 227. Resistance of air, 28. Revival of metals, 263. Rhodium, 350. Rhubarb, test for alkalies, 203. Rochelle salt, 269. Rock crystal, 56 salt, 56. Roll sulphur, 136. Ruby, 265. Rumex acetosa, 231. Safety lamp, 236, 237. Sal alembroth, 307 ammoniac, 204, 356. Saline solutions, 101. Salinity, 358. Salts, 108, 356. Salts of the ocean, 270 of potash, 282 of protoxide of copper, 314 of rhodium, 350-of soda, 2*2. Sanctorio's thermometer, 11. Saturni arbor, 86, 332, 333. Scale of equivalents, 94. Scales of iron, 328. Scheele's green, 337. Scoria, 355. Selenacids, 158. Selenide of antimony, 349 arsenic, 339 bismuth, 324 iron, 330 lead, 319 mercury, 304 tin, 322 zinc, 333 of phosphorus, 217. Selenisalts, 369. Selenium, 108, 140, 141, 142. Selenium acids, or selenacids, 157. Seleniurets, or selenides of phosphorus-, Seleniuretted hydrogen, 171. Self-repellent power of caloric, 55. Self-registering thermometers, 12. Self-regulating reservoir, 58. Sensible heat from electricity, 57. Sesquibasic phosphates, 367t bromide of phosphorus, 217. Sesquicarbonates, 367. Sesquichloride of antimony, 345 of ar- senic, 335, 338 of carbon, 233 of iron, 325. Sesquicyanide of iron, 330. Sesquioxide, 137 oxide of aluminum, 268 of bismuth, 323 of cerum, 365 of chromium, 352 of chromium and iron, 352 of manganese, 354. Sesquiphosphates, 367.t Sesquisulphide of antimony, 345, 347 of arsenic, 335 of iron, 325, 330. Sexsilicate of lead and potash, 368. Shear steel, 325. Silica, 253.t Silicate of alumina, 268 of iron, 325 of magnesia, 271 of potash, 268 of zinc, 331. Silicates, 367. Silicon, 251. t Silicuret of potassium, 284. Silicurets, 368. Silver, 91, 119, 297, 298, 299 arseniate of, 337 ajsenite of, 337 chemical ves- sels, 256 coin, 298. Simple affinity, 89 combination, 89. Simple valve volumeter, 179. Slag, 355. Slaked barytes, or hydrate of, 276. t See Emendations, end of Index, p. xx. INDEX, IX Slaked lime, or hydrate of, 92, 274. Sliding-rod gas measure, 178. Smalt, 354. Smell of arsenic, 342 of selenium, 141. Smoky rock crystal, diathermane proper- ties of, 56. Snow and sulphuric acid, 73. Soaps, 202.* Soda, 92, 286. Sodium, 279, 230, 301 amalgam of, 208 chlorhodiate, 350 chloride of, 285 chloroplatinate of, 295. Solar rays. 57. Solar spectrum, 78, 79. Solid carbonic acid, 229 hydrate of chlo- rine, 119 sulphuric acid, 140. Solids, circulation of heat in, 47 expan- sion of, 6. Solution, 92, 285 produces heat or cold, 62. Solvent of gold, 119. Sores from chromic acid, 353. Sources of heat, 57, 64. Space, specific heat of, 46. Specific gravity, 83, 98. 100, 101, 103. Specific heat, 44, 45, 98 of gases, 46. Spectrum, 79. Spinelle ruby, 265. Splendid combustion, 113, 114, 115. Spodumene, 284. Spongy indium, 297 nickel, 297 palla- dium, 297 platinum, 74, 293, 296 rho- dium, 297. Springs of Virginia, 169. Stalactite, 266. Stalactite, calcareous, 226. States of caloric in nature, 74. Steam, condensation of, 52 decomposi- tion of, 152. Steel, 263, 325. Steel mill for giving light in mines, 236. Strontia, 92, 277 apparatus for evolving, /4/t). t Strontium, 271. Subacetate of copper. 314. Subnitrate of silver, 300. Suboxide of arsenic, 335 of potassium, 283 of silver, 299 of sodium, 283. Suction pump, 19, 20. Sugar of lead, 318. Sulphacids, 158, 288. Sulphate of antimony, 365 of baryta, 276, 365 of bismuth, 365 of copper, 313 of lead, 365 of lime, 3&5 of mag- nesia, 89, 270 of mercury, 365 of sil- ver, 365 of soda, suspended crystalli- zation of, 88 strontia. 365 thorina, 270 tin, 365 yttria, 365. Sulphates, 365. Sulphide of barium, 276 of cadmium, 352 of copper, 315 of hydrogen, or sul- phydric acid, 166, 167 of manganese, 354 of molybdenum, 354 of platinum, 297 of potash, 136 of selenium, 142 of silver, 299 of zinc, 331, 332 Sulphides, 135, 288, 359 of antimony, 349 of arsenic, 338 of iron, 325 of * See Index to Organic Chemistry, t See Index to Electricity. lead, 319 of mercury, 301 of phos- phorus, 217. Sulphites, 366. Sulphobases, 288. Sulphocyanide of iron, 245. Sulphocyanide of potassium, 245. Sulphocyanogen. 245. Sulphosalts, 288, 369. Sulphur, 108, 115, 134 chlorides of, 140. Sulphurets, sulphides, 135, 288. Sulphuretted hydrogen, 160, 170. See Add, sulphydric. Sulphur springs, 169, 299. Supercarbonate of magnesia. 271. Supporters of combustion, 198. Surfaces, radiating, 54. Suroxide, or bioxide, of barium, 276. Symbols, chemical, 96. Sympathetic picture, 169. Synthesis of ammonia, 207 of chlorohy- dric acid, 160 of nitrous acid, 184. Table of affinity, 92 of equivalents, 189 of freezing mixtures, 73, 74 of me- tals, 262 of weights of gases, 104 of volumes, 189. Tanno gallate of iron, i. e. ink, 327. Tantalite, 354. Tantalum (see Columbium), 354. Tartar emetic, 346, 368. Tartrate of iron and potash, 368 of anti- mony and potash, 346, 368 of lead, 317 of potash, 282 of potash and soda, sal Rochelle, 369 of soda, 282.* Tartrates, 368. Telluriacids, 158, 289. Tell urhyd rates, 158. Telluribase, 200. Telluride of mercury, 304. Tellurides, 289, 359. Telluri-salts. 143, 369. Tellurium, 108, 142, 157. Temperature and moisture, 154. Tertium quid, 109, 358. Test of arsenic. 343 of chlorine, 119 of copper, 311 of iodine, 131 of potash, 282 of silver, 119, 298 of soda, 282. Tetartocarbohydrogen, 236, 240. Theory of atoms, 95 of chlorine, 165 of electro-magnetism, appendix of Mello- ni, 56 of phlogiston, 196. Theory of volumes, 187. Thermo-electric batteries, 323. t Thermo-electric pile, 56.t Thermometer of Sanctorio, 11. Thermometers, 10, 14, 36. Thermoscope of Melloni, 56. Thillorier's process for congelation of car- bonic acid, 44, 230. Thomson's equivalents, 94. Thorina. 269, 270. ! Thorite, '269. i Thorium, 269. Tin, 89, 292, 320. Tinder, 221. Tin, crystalline hydrate of, 321. Tin, hydrated bioxide of, 320. I * See Organic Chemistry, 5181 to 5193, also 5^28. t See Index to Electricity. INDEX. Titanium, 355. Topaz, 265. Torricellian experiment, 17. Toughness of metals, 263. Transmission of contagion, 223. Triacetate of lead, 318. Tribromide of gold, 292. Trichloride of gold, 292. Trioxide of gold, 291. Trisulphide of gold, 292. Tritocarbohydrogen, 235. Tubulated retort, figure of, 161. Turmeric, 203, 277. Turpeth mineral, 303. Tungsten, 355. Type metal, 89. Undulations of light, 75. Uranium, 355. Urea, 244. Vacuum, 43, 46, 70, 71 Torricellian, 46. Vanadium, 355. Vapour, 40, 47 Berzelius on, 42 of chlo- ride of carbon, 233 ethereal, 47 of io- dine, 131 of sulphur, 136. Vaporization, 31, 37, 40 cold produced by, 68 of ice, 71. Vegetable colouring matters, 203 char- coal removes them, 222 destroyed by chlorine, 119 by hypochlorous acid, 124 by hypochlorites, 361. Velocity of sound accelerated in hydro- gen, 146. Vinous fermentation, 226. Vitality, a source of heat, 64. Vitrified borax, 356. Vitriolated tartar, i. e. sulphati potassa, 357 Vitriol, colcothar of, 328. Vitriol, oil of, 139. Vitreous compound of antimony, 348. Voice affected by hydrogen, 147. Volatile alkali, 204 oxide of osmium, 351 oxide of selenium, 141. Voltaic current, action of, on phosphorus, 211. Voltaic electricity,! power of fishes,t poles, 109, 197 series, 197.t t See Index to Electricity. Volumes, 187, table of, 189. Volumescope, 149, 185. Volumeter, 178. Water, 150, 151, 153, 154, 257 acts like an acid with bases, 151 acts like an acid with lime, 274 acts like a base with acids, 151 an absorbent, 119, 163, 227 congelation of, 69 expansion of, 9 frozen by boiling ether, 68 in oxalic acid, 231 of crystallization, 87 oxy- genated, 156 pump, 19 basic, See Or- ganic Chemistry and Appendix, for es- says on nomenclature, salt, and radical theory. Weight of air, 104 of the atmosphere, 14, 18 of gases, 104 of fluids, 104 of steam, 104. Weighing in vacuo, 104. Weights, atomic, 96, 97. Welding process, 263. Wheel lap, 44. White hydrate of iron, 326. White sulphur springs, 199. Wild oat, beard of, as an hygrometer, 39, 155. Winds from the African deserts, aridity of. 154. Winds replete with aqueous vapour, 40. Wire gauze, 236. Wollaston's equivalents, 94, 95 cryopho- rus, 71. Wootz, a peculiar variety of steel, 325. Woulf 's apparatus, 163 improved, 163. Yttria, 269. Yttrio cerite, 269. Yttrio tantalite, 269. Yttrium, 269 chloride of, 285. Zaffre, 354. Zinc, 89, 331 acetate of, 90, 333 car- bonate of, 331 cyanide of, 333 fluo- ride of, 333 iodide of, 333 oxides of, 331 selenide of, 333 silicate of, 331 sulphate of, 331 sulphide of, 331. Zirconion, or zirconium, 259. t See Index to Electricity. INDEX TO THAT PORTION OF THIS COMPENDIUM WHICH RELATES TO ORGANIC CHEMISTRY. Absinthine, 528. Acetal, 549. Acetate of ammonia, 460 of tungsten, and of molybdenum, 459 of oxide of amyl, 562 of pepsine, 575. Acetates of lead, 459, 460, 498. Acetated oxide of ethyl, acetic ether, 542, Acetone, 391. Acetous fermentation, 596, 598. Acetyl, or acetule, 377, 392, 547 chloride of, 549, 550 chlorohydrate of chloride of, 549 oxychloride of, 550 trioxide of, 457 trioxide hydrated, 456. Acid, acetic, 379, 456, 458, 547, 597 ace- tous, 471, 547 aldehydic, 547 allox- anic, 488 azomaric, 445 benzole, 382, 441, 450, 476, 492, 588 bromohydric, 479 bromosaliculic, 482 butyric, 425 caffeic, 473 caflfee tannic, 473 ca- pric, 425 caproic, 425 carbonic, 372, 375, 583, 584, 586* cerebric, 573 chlo- ric, 453 chlorochromic, 482 chloro- proteic, 564 chlorosaliculic, 481 cho- leic, 576, 589 cholic, 577 choloidic, 577, 588 cholopholic, 445 cinnamic, 383, 450 citric, 461 citraconic, 462 cocoastearic, 425 crotonic, 425 cyan- hydric, 375* cyanoxalic, 484 cyan- uric, 455 delphinic, 425 dialuric, 490 elaidic, 429 erythric, 487 ethalic, 426 ethero-sulphurous, 537 ethionic, 530 fellinic, 577 formic, 471 formo- benzulic, 478 formous, 471 fumaric, 462 fuming nitric, 449* gallic, 455, 467 glucic, 470 guaiacinic, 464 hip- puric, 383, 477, 492, 588 humic, 584 h nap yposulphobenzoic, 475 hyposulpho- aphthalio,475 hyposulphurous,475 iodosaliculic, 482 isethionic, 475, 530 itaconic, 462 kacodylic, 393 lactic, 460, 568, 598 lignosulphuric, 410- li- * See Inorganic Chemistry. thofellic, 578 malic, 462 margaric, 425, 447 meconic, 451, 469, 497 me- lanic, 481 melassic, 470 mesoxalic, 488 mucic, 399, 471 mycomelinic, 488 myristicic, 425 myronic, 597 nitric, 453* nitroso-nitric, 433* nitro- saliculic, 482 oleic,424, 425,447 oleo- phosphoric, 572, 573 oxalhydric, 470 oxalic, 372* oxaluric, 488 palmatic, 422 parabanic, 486, 488 paratartaric, 462 pimaric, 445 pinic, 445 pyro- gene, 455 pyroligneous, 440 pyro- maric, 445 racemic, 462 ricinic, 425 ricino oleic,425 ricino stearic, 425 saccharic, 470 salicohydric, 479 sali- culic, 481 saliculous, 479, 521 salicy- lous, 479 stearic, 425, 447 succinic, 453, 476 sulphoamylic, 396 sulpho- cyanhydric, 470* sulphogly eerie, 397 sulphomethylic,474 sulphoproteic,564 sulphosaccharic, 475 sulphovinic, 474, 532 sulphuric, 497* sylvic, 445 tannic, 465, 473 tartaric, 417, 462 tartralic, 463 tartrovinic, 474 thionu- ric, 488 uramilic, 489, 490 uric, 484, 485, 579 uric anhydrous, 486 valeri- anic, 473, 562 xan'thoproteic, 564. Acidifiable radicals, 377. Acids, bibasic, 454, 456 from gaultheria, 482- from sugar, 470 monobasic, 454 polybasic, 471 pyrogene, 455 tri- basic, 454, 456 volatile, 427. Aconitia, or aconitine, 512. Aconitum napellus, 512. Adjective dyes, 419. Agedoile, 523. Albumen, 41 1 , 564, 565, 566 animal, 413, 415 vegetable, 413, 415. Alcargen, alcarsin, 393. Alcohol, 374, 384, 468, 547, 598 amylw, 561 ethylic, 384 methylic, 552. * See Inorganic Chemistfy. Xll INDEX. Alcornine, 528. Aldehyde, 389, 547, 548 ammoniated, 548 mesitic, 560, 561 resin of, 549. Alismine, 528. Alkalies, organic, 493, 496 vegetable, 493, 494. Alkaloids, 493. Allaritoin, 487. Alloxan, 486, 487 hydrated, 490. Alloxatin, 486, 489 dimorphous, 490. Almonds, bitter, oil of, 432, 441. Aloes, 451. Altheine, 523. Alumina, 419.* Amanitine, 528. Amber, 443, 452. American oil, 453. Amide, 372, 377, 380. Amido chloride of mercury, 376, 381. Amido subnitrate of mercury, 381. Amidurets, 376. Amiduret of benzule, 442 of hydrogen, 380. Ammeline, and ammoline, 496. Ammonia, 371, 380, 586* benzoate of, 477 cyanate of, 579 hamate of, 584 magnesian phosphate of, 582 purpu- rate of, 490 saliculite of, 480 urate of, 582. Ammoniac, 451. Ammoniacai gas, 434.* Ammonium, 372, 376, 380, 392* oxide of, 455. Amygdaline, 383. Amyl, or amule, 377, 395 bromide of, 562 ethers, 561 iodide of, 562. Amylic alcohol, 561. Analysis of blood, 570 organic, 497 ul- timate, 374 of urine, 581. Angustura, false, 505. Anilina, or aniline, 519, 520. Anhydrous formic acid, 556. Animal growth, 582 life, 586 products, 372 substances, 563. Animine, 496. Anodyne, Hoffman's, 534. Anthracite, 452. Antiaria, or antiarine, 516, 528. Ants, 471. Aorta of the ox, 595. Apirine, 496. Aqua ammoniae, 431.* Arabin, 399 rnetamorphic, 399. Aricine, 504. Arterial fibrine, 567. Arthanitine, 527. Artificial camphor, 439 cold, 539 diges- tion, 590 fat, 425 fibrin, 567 naph- tha, 453 oil of ants, 557 tannin, 466. Asclepine, 528. Asparagine, 523. Asparamide, 523. Asafcetida, 446, 451. Association of vegetable bodies, 375. Astringency, 465. Atropia, atropine, 512, 519. * See Inorganic Chemistry. Azaridine, 496. Balsam of Peru, 383 Tolu, 383, 450. Balsams, 450 Basacigen class, 376. Base, 377. Bases, organic, 493. Basic equivalents, 455. Basic saliculate of lead, 480. Basic sulphate of quinia, 503. Basic water, 453, 455. Bassorin, 399, 452. Bdellium resin, 446. Beans, 568. Bean, tonka, 481. Beer, Bavarian process for, 597. Beeswax, 447. Belladonia, or belladonine, 513. Bengal opium, 526. Benzamide, 383, 442. Benzole, 438. Benzoated oxide of ethyl, 544. Benzoic ether, 544. Benzoate of ammonia, 477. Benzoile, 377. Benzule, 377. Benzule, or benzyl, 377, 382 hydruret of, 441. Berbina, 519. Bezoar stones, 578, 589. Biamido sesquinitrate of mercury, 331. Biamido sulphate of mercury, 381. . Bibasic acids, 454, 456. Bichloride of formyl, 557. Bichlorinated chloride of methyl, 556. Bichlorinated oxide of methyl, 556. Bihydramide, 380. Bihydrate of etherine, 385. Bihydruret of amide, 380. Bile, 576, 587 acids of, 576, 577 sugar of, 578. Biliary calculi, 573, 576, 578. Biline, 577. Biliverdine, 577. Bioxide of lead, 486.* Bisulphide of ethyl, 546. Bitter almonds, oil of, or hydruret of ben- zule, 382. Bitumen, 374, 452. Black elder, 457. Blanchinine, 496. Blood, analysis of, 570 arterial, 567 menstrual, 567 venous, 567, 595. Bone earth, 574 bones, 573. Brain, 572. Bread, leavened, 417. Brewing, Liebig on Bavarian process of, 597. Bromide of acetyl, 550. Bromide of amyl, 562 of ethyl, 545. Bromine with formyl, 557. Bromoform, 558. Bromohydrate of bromide of acetyl, 550. Bromosaliculic acid, 482. Brucia, or brucine, 505. Bryonia alba, 525. Bryonine, 525. * See Inorganic Chnmistry. INDEX. Xlll Buenine, 528. Butter, 422. Butyrin,422,425. Buxine, 496. CafFeina, or caffein, 495, 510. Calcium, 372.* Calculi, 578, 582. Calculus, fusible, 582 mulberry, 582, 588. Camphelene, 440. Camphene, 440. Camphogen, 432. Camphor, artificial, 439. Camphor, 438. Camphor, liquid, 438. Candle, necessity of wick to a, 430. Cane sugar, 402. Canelline, 528. Caoutchouc, 371, 448, 449. Caoutchouchine, 432, 448. Caprin, 422, 425. Caproin, 422, 425. Caramel, 403. Carapine, 496. Carbamide, 381. Carbon, 371.* Carbon, hydrates of, 373. Carbon, hydrurel of, 438. Carbon, perchloride of, 556. Carbonic ether, 543. Carbohydrogen, 562. Carbonic oxide, 375. Carmine, 420. Garni vora, urine of, 581, 590. Cascarilline, 528. Caseine, 568, 569, 411, 418, 564, 567. Cassiine, 528. Castor oil, 427. Castine, 496. Catalysis, 599. Catechu mimosa, 469. Cathartine, 525. Cellulose, 410. Centaurine, 528. Cerain, 447. Cerasin, 399. Cerifera, 447. Cerine, 447. Cerosie, 448. Cetene, 398. Cetraria islandica, 525. Cetrarine, 525. Cetule, or Cetyl, 377, 398, 425, 562 chlo- ride of, 398 hydrated oxide of, 398. Charcoal, or carbon, 372.* Chelidonia, chelidonine, 512. Chelerythrina, 495, 5H. Chelerythrine, 495, 511. Chemical type, 378. Chemico-electric reaction, 409. Chicoccine, 496. Chinova bark, 496. Chinova bitter, 526. Chloral, 551. Chlorarsin, 393. Chloride of acetyl, 549, 550. Chloride of calcium, 374, 433. * See Inorganic Chemistry. Chloride of ethyl, 545. Chloride of mesityl, 560. Chloride of methyl, 556. Chlorides, 377.* Chlorides of forrnyl, 395. Chlorine ether, 549. Chloroform, 558. Chlorohydrate of chloride of formyl, 558. Chlorohydruret, 496, 502, 504. Chlorohydruret of cinchonia, 504. Chlorophyll, 420. Chloroplatinate of chloride of acetyl, 550. Chlorosalicine, 522. Chlorosaliculimide, 482. Chloroxalic ether. 550. Choleateofiead, 577. Choleate of soda, 578. Cholesterine, 570, 573. Chondrine, 572. Chromate of lead, 375. Chyle, 576. Chyme, 576. Cider, 457, 598. Cinchonia, or cinchonine, 494, 504. Cinnamon, oil of, 440. Cinnamule, or cinnamyl, 377. Cinnamyl, hydrate of, 450. Cinnarubrin, 445. Cisampelina, or cisampeline, 495, 518. Clay, 431. Classes of radicals, 377. Cloves, oil of, 440. Coagulated caseine, 568. Coal, mineral, 452. Coal, naphtha, 432. Cocoa, analogous effects as food to those of coffee and tea, 592. Cocoa stearine, 422. Cochineal, 420. Codeia, or codeine, 451, 494, 501, 519. Coffee seeds, 473, 514, 592. Colchicina, or colchicine, 495, 508. Colchicum, 507. Colletine, 528. Colocynthine, 525. Colophonium, colophony, or rosin, 442. Colouring matter, vegetable, or dyes, 419. Columbine, 526. Compound element, 376. Compound radicals, 375, 377. Compounds of proteine, 591. Conina, or coneine, 495, 514. Contraction of arteries, 595. Copaiva, 446. Copal, 446, 453. Copper, carbonate, 403 subacetate, 403.* Coradalina, or coradaline, 495. Coriarine, 528. Cornine, 528. Corticine, 528. Corydalina, 519. Crotonine, 422, 496. Crystallizable sugars, 400. Cubebs, 527. Cubebine, 527. Cucumis colocynthis, 525. Currants, 462. * See Inorganic Chemistry. XIV INDEX, Currarina, or currarine, 495. Cyanapine, 496. Cyanarsin, 393. Cyanate of ammonia, 579. Cyanide of methyl, 555. Cyanides, 377.* Cyanoferrite of quinia, 503. Cyanogen, 372, 377.* Cyclamine, 527. Dalleiochin, 504. Daphnine, 496, 528. Datiscine, 528. Daturia, 513. Dehydrogenation of ethyl, 547. Delphia, or delphine, 506. Delphinine, 422. Density of essential oils, 434. Derivative radicals, 379. Dextrine, 407, 408. Diabetic urine, 401. Diamond, 372.* Diastase, 407, 409. Digestion, artificial, 590. Digitaline, 496. Diosmine, 528. Distillation, 373 dry, 382. Dulcamara, 509. Dyeing, 419. Dyes, 419. Dyslisine, 577. Elaldehyde, 549. Elaopten, 431,438. Elaterium, 525. Emetia, or emetine, 508. Emulsin, 383. Equivalents, basic, 455. Ergot, 401. Ergotine, 526. Ery throprotide of potash, 565. Esenbeckine, 496. Essential oils, 371, 433, 441. Ether, acetic, 542 benzoic, 544 bichlo- rine, 549 carbonic, 543 chlorine, 549 formic, 543 oenanthic, 544 oxalic, 382, 543 sulphuric, 529 sulphurous, 537. Etherine, 385. Etherple, 533. Ethers, simple, 545 formyl, 556. Ethyl, or ethule, 377, 384, 386 bisulphide of, 546 bromide of, 545 chloride of, 545_compounds of, 386 cyanide of, 546 formiated oxide of, 543 hydrated oxide of, 544 oxide, citrate of, 544 cenanthated oxide of, 544 iodide of, 545 selenide of, 546 sulphide of, 545 sulphydrate of the sulphide of, 546 tartrate of the oxide of, 544 telluride of, 546. Eupatorine, 496. Euphorbine, 496. Euphorbium, 451. Excrements, human, 578. Exostosis, 574. * See Inorganic Chemistry. Fagine, 528. False angustura, 505. Fat, 421 of animals, 592. Feathers, 572. Fecula, 399 with potash. 407 with io- dine, 407. Fennel, 436, 439. Fermentable matter of diabetes, 405. Fermentation, 596, 598, 604. Fibrin, 411, 415, 567 arterial, 567 ve- nous, 567. Fixed oils, 426, 429. Flax, 409. Fluoride of calcium, 574. Fluorides, 377. Fluorine, 372. Food in cold climates, 587 in warm cli- mates, 587 of vegetables, 583. Formiated oxide of ethyl, 543 of methyl, 557. Formic ether, 543. Formulae of resins, 446. Formyl, or formule, 377, 395, 557. Fossil copal, 446. Fraxinine, 528. Fumarine, 496. Galbanum, 451. Gamboge, 451. Gas, chlorohydric acid, 530. Gastric juice, 576. Gaultheria, 479, 482, 521. Gelatine, 571,591. Gelatinous tissue, 571. Gentianine, 524. Geraniine, 528. Glass bulbs, analysis of volatile liquids by, 375. Glaucine, 496. Glaucopicrine, 496. Gliadine, 412. Globuline, 569, 570. Glue, 412. See Gelatine. Gluten, 409, 411, 412. ^Glycerine, 397. Glyceryl, or glycerule, 377, 396, 562. Graminivorous animals, 415. Granatine, 528. Grape sugar, 403, 404. Gravel, 588. Grey part of brain, 573. Guacine, 528. Guaiacine, 464, 526. Guaiacum, 526. Guano, 485. Guarana, 510. Gum, 373, 399, 586 arabic, 399 elastic, 448 Senegal, 399 tragacanth, 399. Gypsum, 583. Hair, 566. Halogen bodies, 382.* Harmalina, 519. Heat by arterial contraction, Winns' hy- pothesis, 595. Heavy oil of wine, 476. * See Inorganic Chemistry. INDEX. XV Hederina, 518. Hematosin, 594. Hemp, fibres of, 409, 410. Hesperidine, 528. Hippurates, 478. Hoffman's anodyne, 534. Horn, 566, 572." Honeycomb, 446. Humate of ammonia, 584. Humus, 584. Hydrate of etherine, 385 of potash, 374 of soda, 374. Hydrated oxide of acetyl, 547 of amyl, 473, 561 of ethyl, 385, 534 of formyl, 395__of methyl, 394, 552. Hydruret of amide, 380 of benzule, 382, 441 of cinnamyl, 383. Hypoacetate of ammonia, 548. Hypoacetous acid, 390. Hyponitrate of oxide of methyl, 554. Hyponitrous ether, 539. Hypothetical radical, 384. Hyssopine, 528. Ilicine, 528. Imperatorine, 527. Impure iodide of mesityl, 560. Impurities of rain water, 583. Influence of heat, 373. Insipid sugar, 405. Insoluble, or coagulated fibrine, 567. Iodide of amyl, 562 of ethyl, 545 of me- thyl, 555. Iodides, 377 iodides, alkaline, 519. Iodine, 372.* Ipecacuanha, 508. Iron, 372, 595. Islandica cetraria, 525. Isinglass, 571. Ivory black, 574. Jamaicina, or jamaicine, 496, 518. Jervina, or jervine, 508, 519. Juice, gastric, 576, 591 pancreatic, 576. Kacodule, or kacodyl, 377, 393 chloride of, 393 cyanide of, 393 hydrated tri- oxide of, 393 oxide of, 393 sulphide of, 393. Kreosote, 432, 440, 441. Lactin, 404, 574. Lactucarium, 526. Lactucine, 526. Lakes, 419. Lapathine, 528. Law of substitution, 379. Lentils, 568. Leucine, 565. Life, changes during, 582. Light, polarized, 408* polarization of, by dextrine, 408 by starch, 408 by su gar, 402. Lignin, 373, 407, 408, 409, 452. Lignosulphuric acid, 410. Lignone, 559. Ligus trine, 528. * See Inorganic Chemistry. Lilacine, 528. Lime, oxalate of, 582. Lime-water, 374. Liquid camphor, 438. " iquorice sugar, 405. Liquids, 375. Liriodendrine, 528. Lobelia inflata, 515. Lobelina, 515. Lobeline, 515. Lupuline, 526. Lute, chemical, 448. Lymph, 579. Maceration, 433. Magnesia, 497. Magnesium, 372. Maize, 414. Malt wort, 409. Manna, 406. Manna sugar, 460. Mannite, 406, 460. Manures, 585. Margarine, 422, 425. Meadow saffron, 507. Meconin, 451 , 452. Meconine, 527. Meconium, 588. Melamine, 520. Melampyrine, 528. Mellon, 377, 379. Membrane, arterial composition of, 572. Menispermia, 519. Menispermine, 496. Menthen, 459. Menyanthine, 528. Mercaptan, 546. Mesite, 559. Mesiten, 559. Mesityl, or mesitylene, 377, 560. Metacetone, 391. Metaldehyde, 549. Methal, 560. Methyl, or methule, 377, 394, 471 com- pounds of, 556 cyanide of, 555 ethers, Methylal, 557. Methylic alcohol, 552 ether, 551 mer- captan, 555. Methylous hyponitrous ether, 554. Milk, 404, 457, 460, 574. Mineral coal, 374, 452. Mineral naphtha, 432. Modifications of proteine, 564. Molasses, 401. Molybdenum, peculiar insolubility of its acetate, 459. Momordica elaterium, 525. Monobasic acids, 454, 455 salts, 456. Monkhood, 512. Mordants, 419. Morphia, or morphine, 498. Mould, 585. Mucus, 579. Mudarine, 525. Mulberry calculus, 582, 588. Murexide, 490, 491. * Se Inorganic Chemistry. XVI INDEX. Muriate of morphia, 500. Muscular fibre, 570 tissue, 570. Mushrooms, 401 sugar of, 405. Myrica angustifolia, 447. Myricine, 447. Myristicine, 422. Myrrh, 451. Myrtleberries, 447. Naphtha, 452 artificial, 453. Naphthene, 452. Naphthol, 452. Narceia, 451,501. Narcitine, 528. Narcotina, or narcotine, 451, 501. Nervous matter, 572. Neutral organic principles, 521. Neutral sulphated oxide of methyl, 553. Nicotina, or nicotine, 515, 520. Night shade, 509. Night soil, cause of efficacy as manure, Nitrated hydruret of cinnamyl, 383. Nitrated oxide of methyl, 553. Nitrogen, 372.* Nutrition and growth, 582. Oak galls, 465. Oats, gluten in, 414. Odorine, 496. CEnanthated oxide of ethyl, 544. CEnanthic ether, 544. Oil of amber, 453 of ants, artificial, 557 of anise, 439 of asarurn, 439 of bella- donna, 428 of bitter almond, 384, 432 of black mustard, 432,435 of cloves, 440 of cinnamon, 383, 440 of cubebs, 439 of elecampane, 439 of fennel, 439 of hops, 435 of horse-radish, 435 of mustard, 517 of parsley, 439 of peppermint, 439 of potato spirit, 473 of olives, 423 of onions, 435 of rose, 439 of sassafras, 445 of spirea ulrna- ria, 384, 483 of sunflower, 428 of tur- pentine, 439 of water-pepper, 435 of wine, 533 >of wine, heavy, 533. Oils and fat, 421. Oils, fixed, 421,426. Ole-essence, 431. Olefiant gas, 549.* Olein, 422, 425. Olivile, 528. Olivine, 528. Opium, 451. Organic alkalies, 498 hydrates, 373 sub- stances, 371 tissues, 372. Osmazome, 570. Oxacids, 464.* Oxalate of ammonia, 381. Oxalated oxide of ethyl, 543 oxide of methyl, 555. Oxalic ether, 543. Oxalurate of ammonia, 490. Oxamide, 381,382. Ox bile, 588. Oxide, carbonic, 381 of copper, 374 * See Inorganic Chemistry. cystic, 582 of ethyl, 385 of glyceryl, 397 of mesityl, 560 of methyl, 551. Oxides, 377. Oxidized iron, use of, as a mordant, 419. Oxychloride of acetal, 550. Oxygen, 371.* Oxygen, volatile oils containing, 436. Oxysulphide of acetal, 550. Pahnatine, 422. Palm oil, 422. Papin's digester, 505. Paraffin, 452. Paramenispermine, 496. Paramorphia, 451, 500. Peas, legumen or vegetable caseine in, 414, 568. Peat, 585. Pepsine, 575. Perbromide of formyl, 557. Perchlorate of oxide of ethyl, 541. Perchloric ether, 541. Perchloride of carbon, 556. Perchloride of formyl, 557, 558. Perchlorinated oxide of methyl, 556. Periodide of formyl, 557. Phenomena of fermentation, 600, 602, 603. Phloridzeine and phloridzine, 523. Phosphate of ammonia, 582 of lime, 415. 574, 582. Phosphorus, 372, 415. Phillyrine, 528. Picrolichenine, 525. Picromel, 578. Picrotoxia, or picrotoxine, 516, 519. Pigmentum nigrum, 572. Piper cubeba, 527. Pitayine, 496. Platina sponge and black, 471, 600.* Plumbagine, 526. Polarized light, 408.* Polygala senega, 526. Poplar, 384. Poppy, 519. Populine, 528. Potash, 497. Potassium, 372, 385.* Prirnuline, 528. Principles devoid of nitrogen, 524. Proof spirit, best solvent for gum resins, 451. Proteine, 564 compounds of, 591. Prolide, 565. Protochloride of formyl, 557. Pseudomorphia, 451, 500. Pteleyle, 560 chloride of, 560 nitrated oxide of, 560. Pus, 579. Putrefactive fermentation, 604. Pyretine resins, 443. Pyrethrine, 528. Pyrogene acids, 455 oils, 443 resins, 443. Pyroxylic spirit, 394, 552. Quadroxide of nitrogen, 490. * See Inorganic Chemistry. INDEX. XV11 Quassine, 526. Queen of the meadow, 384. Quinia, or quinine, 501, 519. Quinia, basic sulphate of, 502 neutral sulphate of, 503 phosphate of, 503 salts of, 503, 504. Quinquina bark, 496. Radicals, compound, primitive, deriva- tive, 379. Reagents, chemical, 520. Rennet, alleged cause of its efficacy, 568. Repulsion, 430. Resins, 442 saponification of, 444 table of, 446. Resin of aldehyde, 549 benzoin, 446 colophony, 445 copal, 446 guaiac,446 sandarach, 446. Rhamnine, 528. Rhus vernix, 443. Ricino olein, 425. Ricino stearine, 425. Rickets, 574, Rising of wheat dough, 317. Rosin, 442. Rotation of crops, 586. Rutuline, 523. Rye, gluten in, 414. Sabadilla, 507, 519. Saccharine fermentation, 597. Sago, 406. Salacin, 384, 521, 522. Saliculites, 480. Saliculite of potash, 480. Salicyl, or salicule, 377, 384. Salicyl, hydruret of, 521. Saliretine, 522. Saliva, 575. Salivary glands, 575. Salt.* Salts of morphia, 500. Salts of ethyl, 544. Sambucus niger, 457. Sanguinarine, 496. Santonine, 524. Saponine, 526. Sassarubrin, 445. Saxon blue, 420. Scammony, 451. Scilla, maritima, 525. Scillitine, 525. Scordine, 528. Scutellarine, 528. Secretions, 574. Secretory products, 372. Semen cynte, 524. Seneca oil, 453. Senegine, 526. Serpentarine, 528. Serosity of the blood, 570. Sesquibasic acetate, 460. Sesquicarburet of nitrogen, 377. Sesquioxide of iron, 470. Sexbasic acetate of lead, 460. Siccative oils, 428. * See Inorganic Chemistry. C Silicon, 371, 372.* Silver, saliculite of, 481. Simple ethers, 545. Sinapoline, 435. Skins of animals, 571. Smilacine, 526. Smilax sarsaparilla, 526. Soda, choleate of, 578. Soda, hyponitrite of, 539 nitrate of, 586. Soil for potatoes, 585. Solanacae, 519. Solania, or salanine, 509. Solvent of oils, 433,434. Spartine, 528. Spermaceti, 398, 444. Spigeline, 528. Spirea ulmaria, 479. Spirit of Mindererus, 460. Staphisia, 519. Starch, 373, 406, 586. Starkey's soap, 434. Stavesacre, 506. Stearate of potash, 425. Stearine, 422. Stearopten, 431, 438, 481. Stones, bezoar, 578, 589. Straw, 410. Strychnine, 505. Strychnos, nux vomica, 505. Suavin, 401. Subordinate radicals, 377. Substantive dyes, 419. Suet, 444. Sugar, 373, 399, 401 anhydrous grape, 403 of bile, 578 of the cane, 402 diabetic, 402 grape, 402 liquorice, 402 of manna, 402 of milk, 402, 404 mushroom, 402, 405 of lead, 460 un- fermentable, 405, 406 acts as an acid, 403. Sugars, 400. Sulpharsin, 393. Sulphate of ether, 475. Sulphate of ether and water, 474. Sulphated oxide of elayl, 475. Sulphate of indigo, 420. Sulphide of ethyl, 545 of methyl, 555. Sulphocyanide of potassium, 575. Sulphur, 372, 415. Sulphuric ether, 529. Sulphurous ether, 537. Summer strained oil, 422. Surinamina, or surinamine, 496, 518. Sweat, 457. Sweet spirits of nitre, 540. Symbols, 377. Synaptase, 383. Synthesis, 372. Syrups, 400. Table of alkalies, 494, 495. Table of oxygen oils, 436. Tallow, 426, 444. Tanacetine, 528. Tanghinine, 527. Tannin, artificial, 466. * See Inorganic Chemistry. XV 111 INDEX. Tantalum, 466. Tapioca, 406. Taraxacine, 523. Tartar, cream of, 462. Tartarized iron, 462. Tartrate of potash and soda, 462. Tar water, 440, 592. Taurine, 577. Tawed leather, 571. Tea, 510. Teeth, 574, 592. Terebene, 440. Tests of morphia, 500, 520. Thebaina, or thebaine, 500, 519. Theine, 510, 592. Theobromia, 519. Thiosinnamina, 517. Titanium, 466. Tobacco, oil of, 428. Tonka bean, 481. Torrefaction, 407. Trernelline, 528. Trioxide of acetyl, 457. Tungsten, peculiar insolubility of its ace- tate, 459. Turpentine, oil of, 433. Ulmin, 452. Ultimate analysis, 371. Uncrystallizable sugars, 401. Uramile, 489, 490. Urate of ammonia, 485, 582. Urate of potash, 485. Urea, 579. Urea, nitrate of, 580. Uril, 484, 487. Urinary calculi, 582. Urine, 457, 492, 579 acid and alkaline, 581 of birds, 581 carnivora, 581 of the herbivora, 581 of serpents, 581. Valeryl, 473. Varnish, 428. Vegetable acids, 374 alkalies, 493. Vegetable albumen, 413 caseine, 411, 415, 418 elements, 418 fibrin, 415 growth, 582 life, 586 substances, 371 Vegeto-alkalies, 493. Vegeto-animal ferment, 597. Vegeto-animal substances, 411. Veratria, 507, 519. Veratrine, 507. Veratrum sabadilla, 507. Venous blood, 595 fibrine, 567. Vinegar, 457. Vinous fermentation, 597. Violine, 496. Viscous fermentation, 598. Volatile bases, 519 oils, 429, 434 oils formula of, 436. Watch work, oil for, 423. Water, 373, 374* rain, contains ammo- nia, 583. Waves, abating influence of oil on, 430. Wax, 446, 447, 592. Wheat, 413, 416. White helebore, 507. Will and Varentrap's process for nitro- gen, 374. Willow, salycyl or salicin, from bark of the, 384. Winter strained oil, 422. Wood, 409 distillation of, 457. Wood spirit, 395, 552. Wool, dyeing of, 420. Wort, 401, 409, 597. Xanthopicrine, 525. Xanthic oxide, 582. Xylit, 559. Xylite, 559. Xylite naptha, 560. Xylite oil, 560. Yellow wax, 447. Zedourine, 528. Zimome, 412. * See Inorganic Chemistry. EMENDATIONS 'ding the Isomeric Acids of Phosphorus, the Atomic Weight of Silicon, and Composition of Silica. It will be perceived by the readers of that portion of this Com- pendium which treats of " acids relatively to the proportion of base required for saturation"(51Sl), that a new doctrine has been ad- vanced on that subject. Consistently a very important modification has been made with respect to the three previously supposed isome- ric states of phosphoric acid (1153). They are inferred to differ from each other only in the proportions of water, or other base which they require severally for their saturation; so that there is a monobasic, a bibasic, and tribasic phosphoric acid (5184). When in the state heretofore designated as free, they are considered as con- stituting three phosphates of water. This assumed constitution of these isomeric acids has been represented by Dr. Kane, and other respectable chemists, as affording strong evidence of the existence of compound radicals in certain salts. Hence having, in arguing against the existence of such radicals, adverted to the constitution of the dif- ferent phosphates of water,* I deem it expedient to give, in the lan- guage of Dr. Kane,t an account of the acids of phosphorus to which reference is made, and of their habitudes with basic water and other bases. "The Phosphoric acid has a great affinity for water, combining with it almost ex- plosively. It may form three distinct compounds, phosphates of water, the constitu- tion of which is as follows: Monobasic phosphate of water, - - PO 5 + HO. Bibasic phosphate of water, - - PO + 2HO. Tribasic phosphate of water, - - PO + 3HO. This relation was first established by the researches of Graham. Phosphoric acid combines not only with water in these three proportions, but each of them is a type of a series of salts, which the phosphoric acid is capable of forming. Thus, there is a class of monobasic phosphates, another class of bibasic phosphates, and a third, which is the most common, of tribasic phosphates; the water contained in the phosphates of water being replaced to a greater or less extent, by means of equivalent proportions of ammonia or metallic oxides. A solution of phosphoric acid in water, may contain any one of the three phos- phates of water that have been described, and when neutralized by bases may hence produce totally different salts. The properties of a solution of phosphoric acid may, therefore, be totally different according to the manner in which it had been prepared, and hence this acid was at one time ranked as a remarkable instance of isomerism ; but Graham has beautifully shown, that the difference of properties is only the result of the existence of the different states of combination in which the phosphoric acid actually exists. It will consequently be necessary to study separately the properties of the three compounds of phosphoric acid with water. iwbasic Phosphate of Water. -A solution of this body reacts powerfully acid, it precipitates albumen (white of egg) in white curds; when neutralized by a -alts which contain but on<; atom of base, their formula being PO^ -\- RO; and a soluble salt of it produces in solutions of silver, a white, soft, precipitate, PO 5 -f- effort to refute the arguments in favour of the existen^o-^ ^mphide salts of a compound radical like cyanogen. t Elements, page 485. XX AgO. This is the least stable of the phosphates of water, it gradually passes into the other forms, particularly when its solution is boiled. Bibasic Phosphate of Water. This form of the acid may be prepared by decompo- sing bibasic phosphate of lead by sulphuretted hydrogen. Jt is characterized by combining always with two equivalents of base, forming salts, whose formula is I'd* 4- 2RO; its salts give, with nitrate of silver, a white precipitate, PO* -j- 2AgO, which is not pasty like the monobasic phosphate. The salts of this acid may contain only one equivalent of fixed base, the other being water, and may hence, at first sight, appear to be constituted like the monobasic salts ; the basic water is, how- ever, easily known to be present, by its not being expelled by a moderate heat, with the water of crystallization, but requiring a temperature approaching to ignition for its expulsion. Tribasic Phosphate of Water. This is the form of phosphoric acid which represents the class of salts most generally known ; it is characterized by not precipitating al- bumen, and by combining with three equivalents of base when fully neutralized. In the majority of cases of the three equivalents of base, one is water; thus the com- mon phosphate of soda is a tribasic phosphate, its formula being (PO 5 -}- 2NaO.HO) 4- 24Aq; when moderately heated, or even by long exposure to dry air, it loses the 24Aq, but it requires to be melted at a red heat, in order to drive off the twenty-fifth atom of water; and if this be done, on redissolving the fused mass in water, it crys- tallizes in a totally different form, and is found to have been changed into bibasic phosphate of soda, the formula of which is (PO + 2NaO) -f- lOAq. The difference is remarkably shown by the action of these salts on a solution of silver ; common phosphate of soda precipitates nitrate of silver of a canary yellow, and the solution becomes acid ; one equivalent of tribasic phosphate of soda, decomposing three equi- valents of nitrate of silver, producing one equivalent of tribasic phosphate of silver, two of nitrate of soda, and one of nitrate of water; this last being liquid nitric acid, of course renders the liquor acid. The reaction may be simply expressed PQ5 + 2NaO.HO and 3 (NO -J- AgO) give PO- -f 3AgO . . . 2(NO* + NaO) and NO 3 4- HO. If on the other hand, bibasic phosphate of soda be used, the liquor remains neutral, for PO5 4- 2NaO and 2(NO* 4- AgO) give PO* 4- 2AgO and 2(NO* 4- JNaO). In the tribasic phosphates, it frequently occurs, that there shall be but one equi- valent of fixed base, the other two being water; such salts have frequently an acid reaction, and were formerly called biphosphates. Thus one tribasic phosphate of soda is PO 3 4- NaO.2HO; the biphosphate of ammonia is tribasic, its formula being PO' 4- NHO. 2HO. These salts of phosphoric acid were originally designated by Graham, metaphos- phates, pyrophosphates, and common phosphates." It may be proper to add that the opinion of Professor Rose re- specting the identity in composition of the different kinds of phos- phuretted hydrogen(1166), of which one only is spontaneously in- flammable, has been confirmed. According to analysis, either con- sists of an atom, or volume, of phosphorus and three atoms, or six volumes, of hydrogen, the whole aggregate being condensed into four. Their unlikeness, as respects spontaneous inflammability, is ascribed to the presence of impurities which tend either to promote or to re- tard reaction with atmospheric oxygen. fltomic Weight of Silicon and Composition of its Oxide. Jn this Compendium (1361), the equivalent of silicon is stated to be 8, and that taking one atom of oxj^gen to form silicic acid, the equivalent of this compound, known also as silex or silica, is 16. But latterly it has been inferred that the equivalent of silicon is 22.22 And that to form silicic acid it takes 3 atoms of oxygen = 24. -~ -,* Consistently the equivalent of silicic acid is 46.22 RETURN TO the circulation desk of any University of California Library or to the NORTHERN REGIONAL LIBRARY FACILITY Bldg. 400, Richmond Field Station University of California Richmond, CA 94804-4698 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS 2-month loans may be renewed by calling (510)642-6753 1-year loans may be recharged by bringing books to NRLF Renewals and recharges may be made 4 days prior to due date. DUE AS STAMPED BELOW SEP 2 3 2001 r~ _ 12,000(11/95) UNIVERSITY OF CALIFORNIA, BERKELEY FORM NO. DDO, 15m, 2/84 BERKELEY, CA 94720 f