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J> _> >'3 > J» » »J > > V"> > > ^ ■ >■ , ■ > >>>>.> ^> y Z> > * >•) ]> > > ^> J> ~> >» > -•> '"> » Z> J> p>>."t> > > ^ i" >>■>"> :> >.: > > >5 3>.>3[> > >> > ^> .... xx> r~> >» >.■'>-» > ^» >3>>^> ^r yy> y h V* t * fci SYSTEM / • OF CHEMISTRY FOR * THE USE OF STUDENTS OF MEDICINE 'J ^ v BY FRANKLIN BACHE, M. D. MEMBER OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA. at the sa™ «™> ^ I P I , In -haV,ng pursUed this Plan> therefore the advantage has been gained of avoiding fractions in the equi- valent numbers of the different chemical substances. PREFACE. v The compound ponderable bodies are considered under the four heads of salifiable bases, acids, salts, and unsalifiable com- pounds. The expression, salifiable base, as applicable to those bodies, which form, with acids, neutral compounds, for the most part crystallizable and soluble, is sanctioned by the usage of the best chemical writers of the present day, and may now be consi- dered as constituting a part of the scientific language of che- mistry. This mode of appellation, I have adopted without hesi- tation, but I have not followed the usual nomenclature of the divisions of the salifiable bases. Thus I have used the expres- sion of alkaline salifiable bases, to designate the compounds, usually distinguished by the separate appellations of alkalies, and alkaline earths, retaining no division corresponding to the latter. To the bodies, usually called earths, I have assigned the name of earthy salifiable bases, and to the compounds, which are generally denominated metallic oxides, I have applied the expression of salifiable bases, not alkaline or earthy. The arrangement of the acids into five classes has been found- ed upon the relations of their various bases to oxygen and hy- drogen, which bodies are considered as acidifying principles. This arrangement is entirely artificial, and has no other purpose than that of suggesting the composition of the different acid bo- dies. An account of the principles, which govern it, has been given in a separate chapter in the body of the work. In treating of the salts, I have thrown them into as many classes, as there are salifiable bases, formed from distinct radicals. If I had adhered to uniformity in the arrangement of these com- pounds, perhaps I should have considered them in as many sets, as there are salifiable bases themselves. By doing so, however, I should have separated salts, which stand more naturally toge- ther. For example, I should have had a class of salts, formed from the protoxide of iron, and another class, formed from the peroxide; but as the salifiable bases, present in these salts, have a common radical, they could not be considered with advantage separately. In distinguishing the different classes of salts, I have never employed the name of the radical, which may furnish the salifiable base or bases, present in them. Hence it is, that, in the following work, the expressions, salts of iron, salts of lead, salts of mercury, &c. never occur. When the chemist speaks of the salts of potash, the expression is strictly correct, and desig- nates all those salts, in which potash is present as a salifiable base. When, however, he speaks of the salts of iron, the mode of ex- pression is devoid of the same precision, and distinguishes the salts, formed from those salifiable bases, which contain iron as their radical. In strict propriety, it is as incorrect to speak of a salt of iron, as it would be to speak of a salt of sodium or a salt of potassium. VI PREFACE. This want of uniformity in the nomenclature of salts, how- ever trifling, in its influence, it may be considered by the initiated chemist, is nevertheless a source of considerable embarrassment to the student, who undertakes a course of elementary studies in chemistry for the first time. Acting under the conviction, therefore, that the mere student in chemistry might be misled from the influence of this errone- ous mode of nomenclature, I have endeavoured to overcome the difficulty by adopting a new plan for designating the classes of salts, usually distinguished by the names of the radicals of the salifiable bases present in them. For example, I have appro- priated, to the salts formed from the protoxide and peroxide of iron, the title of salts of oxidized iron, instead of the usual one, of salts of iron. The expression, oxidized iron, when thus em- ployed, may be viewed as a generic one, including under its meaning the two distinct oxides of iron. When, however, this mode of expression is used to distinguish salts, formed from salifiable bases, whose radicals furnish but one of these com- pounds respectively, it should be viewed merely as a more con- cise appellation, than the adoption of the name of the salifiable base itself would furnish. Thus, although the expression, salts of the oxide of silver, is equally correct with that of salts of oxi- dized silver, yet the latter is always preferred. Although I have, in the manner just explained, deviated from the usual methods of distinguishing particular classes of salts, I have not ventured to make corresponding deviations from the usual nomenclature of the salts themselves. I have been thus particular in explaining the peculiar mode, which has been adopted in naming certain classes of the salts, as explanations on the point were inadvertently omitted in the body of the work. The fourth division of compound ponderable bodies has for its title, unsalifiable compounds. Under this head, I have ar- ranged several important substances, which could not stand with propriety in the other divisions of the compound bodies. The epithet unsalifiable, as here applied, although not altogether unexceptionable, is more appropriate than any other which has occurred to me. Having finished the account of ponderable matter, I proceed to consider the imponderable bodies. Light and heat are the only ones considered. Light occupies but very little attention, as not being a legitimate ojbject of chemical investigation. Heat, however, is treated of much more fully, and, in some respects, in an original manner. According to the arrangement, which I have adopted, the general principles of chemical action are next considered. Up- on this subject, very little has been said; but, perhaps, as much PREFACE. vii space has been devoted to the subject, as could with propriety be appropriated to it, without swelling the work to an inconve- nient size, or excluding matter of practical importance. In the second part of the work, the application of the science of chemistry is not made to the examination of all the depart- ments of nature. Mineralogy is too extensive a science, and too remotely connected with the more immediate object of the work, to have permited its introduction with any prospect of advan- tage. I have, therefore, entirely omitted any chemical examina- tion of m.nerals. The chemistry of vegetable and animal sub- stances, however, is given, and treated of in the partial manner, as already explained. While on the subject of the second part of the work, I ought to mention, that I have commenced it with the chemical account of the atmosphere and water. Perhaps these subjects should, more properly, have had a place in the first part; but I was unable to assign to them any position in this part, where they could stand with even tolerable propriety. The chemical nomenclature of the present work differs, in many respects, from that in general use, and is sometimes indeed peculiar to myself. Whatever may be the defects of the one, which I have adopted, I have, at least, avoided the error of re- commending one plan of nomenclature, and adopting another in chemical descriptions. It is certainly due from the sincerity of a chemical writer, that he should be the first to adopt the alte- rations, which he may suggest. I have adopted a system of che- mical terms, from various sources, without regard to their being the ones in current use, under the impression, that it was the most appropriate, which could be used, in the present state of the science. This system of terms, I have uniformly adhered to in chemical descriptions. With regard to the names adopted, which are not in current use in this country, I feel very desi- rous that some of them should get into general use. I here allude particularly to the chemical names, invented by Gay-Lussac, of hydrochloric acid and hydrocyanic acid, instead of the usual ones of muriatic acid and prussic acid. About the fate of the names, which I have myself proposed, I feel little so- licitous. I have, however, been unwilling, that what might otherwise be useful, should be less so, in consequence of my innovations; and, accordingly, I have always introduced the current names (in parentheses) in explanation of the new names. Should, therefore, my suggestions in nomenclature, after being submitted to canc'id criticism, be deemed injudicious, the com- prehension of the facts, detailed in the work, will not be the less easy, from their having been proposed. I have made a similar us? of current names, in explanation of all parts of the nomen- clature adopted, which are not in familiar use. viu PREFACE. To this general account of the work, it is proper to add, that tables have been given of the more important chemical sub- stances. This plan has been pursued with regard to all the un- decompounded bodies, and also with regard to the salifiable bases and acids. These tables, I permit myself to believe, will be found useful to the student of chemistry, as well by re- capitulating the information contained in the text, as by present- ing interesting comparative views of the properties of the differ- ent sets of chemical bodies. I have also given a view of the classification pursued of the undecompounded and compound bodies, in the tabular form. It is proper, before closing this preface, that I should say something on the subject of the sources, from which the present work has been compiled. The great mass of my materials have been derived from the fifth edition of Dr. Thomson's system, published in 1817. This work is the most comprehensive one on chemistry in the English language, and contains an abstract of every thing of importance, which has been done in the sci- ence. In preparing the chemical part of the present work, I have availed myself of the information contained in this system, as far as it was applicable to my purpose. Whenever I have found it silent or unsatisfactory on any particular point, I have sought for information elsewhere, and principally in Accum's and Da- vy's works, and Nicholson's Chemical Dictionary. Occasionally, I have consulted Coxe's edition of Henry's Chemistry. For the pharmaceutical chemistry, and for the notices of the medicinal properties of the various chemical preparations, I am indebted almost exclusively to Coxe's Dispensatory. In compiling the department of the work, devoted to the chemistry of animals, I have occasionally derived my facts from Johnson's Animal Chemistry. While I have thus compiled the work from the most approved systems of the day, I have not been unmindful, that, meanwhile, the science, of which I was treating, was in a progressive course of improvement. In order, therefore, that it might contain all important discoveries, up to the present time, I have consulted the periodical journals on chemistry. From these sources, I have derived the facts, contained in the sections on selenium and its acid compounds, on cadmium, wodanium, lithia and thorina, on the purpuric and sorbic acids, and on strychnin; and also the notices, which I have given, of the discoveries of The- nard, on the oxidizement of water and the acids. In all these cases, the authority is quoted at the foot of the page. November, 1819. CONTENTS. Page Part I. Science of Chemistry,...........2 Book I. Of Ponderable Bodies,..........3 Division I. Of Undecompounded Ponderable Bodies, . . ib. Chap. I. Of Undecompounded Supporters of Combustion, 4 Sect. 1. Of Oxygen, ..........ib. 2. Of Chlorine,..........6 3. Of Iodine, ..........11 4. Of Fluorine, . .........12 Chap. II. Of v ndecompounded Incombustibles, ... 13 Sect. 1. Of Azote, ..........ib. Chap. III. Of Undecompounded Combustibles, ... 17 Class I. Acidifying Combustibles, ......18 Sect. 1. Of Hydrogen, .........ib. Class II. Acidifiable Combustibles,......20 Sect. 1. Of Carbon,...........ib. 2. Of Boron, ...........25 3. Of Phosphorus,..........26 4. Of Sulphur,...........32 5. Of Arsenic,...........35 6. Of Chromium,..........37 7. Of Molybdenum,.........39 8. Of Tungsten,..........40 9. Of Columbium,..........42 10. Of Selenium,..........43 Class III. Intermediate Combustibles,.....44 Sect. 1. Of Antimony,..........ib. 2. Of Tellurium,..........48 Class IV. Basifiable Combustibles,......50 Sub-Class I. Alkalifiable Combustibles, . . . . ib. Sect. 1. Of Potassium,..........ib. 2. Of Sodium, ..........54 3. Of Lithium, ..........58 4. Of Calcium, ..........ib. 5. Of Barium,...........60 6. Of Strontium,..........62 7. Of Magnesium, .........63 Sub-Class II. Basifiable Combustibles, forming, with Oxygen, Earthy Salifiable Bases, . 64 Sect. 1. Of Yttrium,...........ib. 2. Of Ghicinum, . . •.......65 b CONTENTS. \ Sect. 3. Of Aluminum...........1~' 4. Of Zirconium,..........?b 5. Of Thorinum,..........}»' 6. OfSilicum,...........ib. Sub-Class III. Basifiable Combustibles, forming, with Oxygen, Salifiable Bases, which are neither Alkaline nor Earthy, . • 67 Sect. 1. Of Iron. ib. 2. Of Nickel,...........J£ 3. Of Cobalt,............" 4. Of Manganese, .........^9 5. Of Cerium,...........82 6. Of Uranium............83 7. Of Zinc,............8J 8. Of Lead,............87 9. Of Tin,............91 10. Of Copper,...........9*J 11. Of Bismuth,..........." 12. Of Mercury, ..........1°° 13. Of Silver,............108 14. Of Gold.............no 15. Of Platinum,.........113 16. Of Palladium...........H6 17. Of Rhodium, ..........117 18. Of Iridium,...........118 19. Of Osmium, ..........119 20. Of Titanium,..........120 Chap. IV. Account of the Arrangement of the Unde- compounded Ponderable Bodies, . . . .125 Chap. V. Sketch of the Atomic Theory of Chemical Com- bination, ............139 Division II. Of Compound Ponderable Bodies, .... 148 Chap. I. Of Salifiable Bases,..........149 Class I. Alkaline Salifiable Bases,.......ib. Sect. 1. Of Ammonia,..........ib. 2. Of Potash,...........154 3. Of Soda,............158 4. Of Lithia ...........159 5. Of Lime, ...........160 6. OfBarytes,...........163 7. Of Strontian,..........165 8. Of Magnesia,..........167 Class II. Earthy Salifiable Bases,.......168 Sect. l.OfYttria,............169 2. OfGlucina,...........170 3. Of Alumina,...........171 4. Of Zirconia,...........172 5. Of Thorina,...........173 6. Of Silica,............174 CONTENTS. XI Class III. Salifiable Bases, not Alkaline or Earthy, . 177 Chap. II. Of Acids,.............134 Class I. Acids, whose Bases form Acid Compounds with Oxygen or Hydrogen indifferently, . ib. Sect. 1. Of Chloric Acid,.........ib. 2. Of Oxychloric Acid,........185 3. Of Hydrochloric Acid,.......186 4. Of Iodic Acid,..........194 5. Of Hydriodic Acid,........195 6. Of Sulphuric Acid,........196 7. Of Sulphurous Acid,........200 8. Of Hyposulphurous Acid,......201 9. Of Hydrosulphuric Acid.......202 10. Of Hydrosulphurous Acid,......204 11. Of Selenie Acid,.........ib. 12. Of Hydroselenic Acid,.......205 13. Of Telluric Acid, • • *.......206 14. Of Hydrotelluric Acid,.......207 Class II. Acids, whose Bases form Acid Compounds with Oxygen only,........ib. Sect. 1. Of Nitric Acid..........208 2. Of Nitrous Acid,.........212 3. Of Hyponitrous Acid,.......ib. 4. Of Carbonic Acid,........213 5. Of Boracic Acid,.........215 6. Of Phosphoric Acid,........216 7. Of Phosphorous Acid,.......218 8. Of Hypophosphorous Acid,.....219 9. Of Arsenic Acid..........220 10. Of Arsenious Acid,........ 221 11. Of Chromic Acid,.........223 12. Of Molybdic Acid, . . •.....224 13. Of Molybdous Acid,........225 14. Of Tungstic Acid,.........ib. 15. Of Columbic Acid,........226 16. Of Antimonic Acid,........227 17. Of Antimonious Acid*.......ib- Class III. Acids, whose Bases form Acid Compounds with Hydrogen only, ....... 228 Sect. 1. Of Hydrofluoric Acid,.......ib. 2. Of Hydrocyanic Acid,.......230 Class IV. Acids of Irregular Constitution, .... 236 Sect. 1. Of Chlorocarbonic Acid,......ib. 2. Of Chloriodic Acid,........237 3. Of Borofluoric Acid,........238 4. Of Silicofluoric Acid, .......239 5. Of Chlorocyanic Acid,.......241 6. Of Sulphocyanic A cid........242 7. Of Ferrocyanic Acid, . . %.....243 Xll CONTENTS. Class V. Acids in which Oxygen and Hydrogen arc both present,.......... l~4<> Sect. 1. Of Uric Acid...........247 2. Of Purpuric Acid,.........248 3. Of Gallic Acid, .........249 4. Of Formic Acid,.........250 5. Of Oxalic Acid,..........251 6. Of Sorbic Acid,..........253 7. Of Succinic Acid, . . . !■.....254 8. Of Acetic Acid,.........255 9. Of Tartaric Acid,.........258 10. Of Benzoic Acid,.........260 11. Of Saclactic Acid,.........261 12. Of Citric Acid, .........262 13. Of Mellitic Acid, ........265 14. Of Camphoric Acid,........266 15. Of Malic Acid..........ib. 16. Of Lactic Acid,.........267 17. Of Pyrotartaric Acid,.......268 18. Of Moroxylic Acid,........269 19. (if Suberic Acid,.........270 20. Of Laccic Acid,.........ib. 21. OfKinic Acid, .........271 22. Of Zumic Acid,.........272 23. Of Boletic Acid,.........ib. Chap. III. Definition and Classification of Acids, . . 283 Chap. IV. Of Salts, ............286 Sect. 1. Salts of Ammonia,........287 2. Salts of Potash, .........294 3. Salts of Soda,..........310 4. Salts of Lithia, .........322 5. Salts of Lime,..........323 6. Salts of Barytes,.........331 7. Salts of Strontian, ........335 8. Salts of Magnesia,........338 9. Salts of Yttria,..........343 10. Salts of Glucina,.........344 11. Salts of Alumina,.........346 ] 2. Salts of Zirconia,.........351 13. Salts of Thorina,.........352 14. Salts of Silica,..........353 15. Salts of Oxidized Iron,.......ib. ] 6. Salts of Oxidized Nickel,......363 17. Salts of Oxidized Cobalt,......364 18. Salts of Oxidized Manganese,.....365 19. Salts of Oxidized Cerium,......367 20. Salts of Oxidized Uranium,......368 21. Salts of Oxidized Zinc,.......369 22. Salts of Oxidized Lead,.......374 C3. Salts of Oxidized Tin,.......379 24. Salts of Oxidized Copper,......381 CONTENTS. xin Sect. 25. Salts of Oxidized Bismuth,......386 26. Salts of Oxidized Mercury,......387 27. Salts of Oxidized Silver, ......394 28. Salts of Oxidized Gold,.......397 29. Salts of Oxidized Platinum,......399 30. Salts of Oxidized Palladium,.....400 .. 31. Salts of Oxidized Rhodium,......401 32. Salts of Oxidized Iridium,......402 33. Salts of Oxidized Osmium, .....402 34. Salts of Oxidized Titanium, . . , . . ib. 35. Salts of Oxidized Antimony,.....403 36. Salts of Oxidized Tellurium,.....408 Chap. V. Of Unsalifiable Compounds, ......409 Sect. 1. Of Alcohol,...........ib. 2. Of Ethers............412 3. Of Volatile Oils,.........416 4. Of Fixed Oils,..........418 5. Of Spermaceti,..........422 6. Of Soaps, ...........ib. Book II. Of Imponderable Bodies,.........427 Chap. I. Of Light,.............ib. Chap. II. Of Heat,.............430 Sect. 1. Of the Nature of Caloric,......ib. 2. Of the Agencies by which Caloric is put in motion,............431 3. Of the different ways, in which Caloric tends to a state of rest.........440 1. Radiation of Heat,........ib. 2. Conduction of Heat,...... . 442 4. Of the relative quantities of Heat existing in Bodies,.......« . . . 444 5. Of the Changes produced by Caloric in Bo- dies, .............445 1. Changes in Bulk.........ib. 2. Changes in State,........447 3. Chemical Changes,........453 6. Of Instruments for measuring the Intensity of Heat,...........454 1. Common Thermometer,......ib. 2. Leslie's Differential Thermometer, . . 455 3. Wedgewood's Pyrometer,.....456 Book III. Of the General Properties of Matter, upon which Chemical Changes depend,........457 Chaf. I. Of the Attraction of Aggregation, .... .458 Chap. II. Of Chemical Affinity,........f 459 Part II. Chemical Examination of Nature,....... 463 Book I. Of the Atmosphere and Water generally, . . . .464 Chap. I. Of the Atmosphere,..........465 Chap. II. Of Water,............470 0 xiv CONTENTS. Book II. Vegetable Chemistry...........476 Chap. I. Of the Proximate Constituents of Vegetables, . ib. I. Proximate Constituents of the First Set, • . 477 Seot.1. (f Vegetable Acids,........lb- 2. Of Tannin,...........478 3. Of Sugar............480 4. Of Sarcocoll,..........482 5. Of Gum,............ib. 6. Of Mucus,...........483 7. Of Jelly.............484 8. Of Ulmin, ...........484 9. Of Colouring Principles,.......485 10. Of Bitter Principles,........ib. 11. Of Nicotin,...........487 12. Of Extractive,..........488 13. Of Emetin,...........489 II. Proximate Constituents of the Second Set, 490 Sect. 1. Of Morphia,...........ib. 2. Of Strychnin...........491 3. Of Asparagin,..........492 4. Of Cerasin,...........493 5. Of Inulin..........• . . ib. 6. Of Starch,...........494 7. Of Indigo,...........496 8. Of Gluten,...........497 9. Of Pollenin,...........499 10. Of Fibrin,...........ib. ■ III. Proximate Constituents of the Third Set, . ib. Sect. 1. Of Oils,............ib. 2. Of Wax,............500 3. Of Camphor,...........501 4. Of Bird-Lime,..........503 5. Of Resins,...........ib. 6. Of Guaiacum,..........506 7. Of Balsams,...........507 8. Of Gum-Resins,.........508 9. Of Caoutchouc,..........511 IV. Proximate Constituents of the Fourth Set, 512 Sect. 1. Of Cotton,...........ib. 2. Of Suber,............513 3. Of Medullin,...........ib. 4. Of Lignin,...........ib. 5. Of Fungin,...........514 V. Proximate Constituents of the Fifth Set, . 515 >f.ct. 1. Chlorides,...........ib. 2. Acids,.............ib. 3. Salifiable Bases..........ib. <"V\p. II. Of th*> Ultimate Constituents of Vegetables, . 518 CONTENTS. xv Book III. Animal Chemistry,........ . . . 520 Chap. I. Of Animal Constituents, ........ ib. Sect. 1. Of Gelatin............ib. 2. Of Albumen...........522 3. Of Fibrin,............524 4. Of the Colouring Matter of the Blood, . . 525 5. Of Mucus,...........526 6. Of Osmazome,..........527 7. OfPicromel...........ib- 8. Of Urea.............528 9. Of Saccharine Matter,.......530 10. Of Cantharidin,.........531 11. Of Cochenilin,..........ib. 12. Of Oils.............531 13. Of Animal Resins,.........532 14. Of Compound Substances, described in the first part of the work, as Animal Consti- tuents, ............533 Chap. II. Analysis of Animal Substances,.....534 I. Organized Parts,..........*b. Sect. 1. Of Bone,............535 2. Of Nail,............536 3. Of Muscle,...........lb- 4. Of the Skin, ..........538 5. Of Membrane, Tendon, Ligament and Car- tilage, ...........539 6. Of Gland, ...........540 7. Of Brain and Nerve, .......ib. 8. Of Marrow,...........542 9. Of Hair.............54S II. Healthy Products, ........544 Sect. 1. Of Chyle, ...........ib. 2. Of Blood, ...........546 3. Of Feces,............548 4. Of Saliva,...........550 5. Of the Gastric Secretion,......551 6. Of the Pancreatic Secretion, ..... 553 7. Of Bile,............ . ib. 8. Of Tears,............554 9. Of the Mucus of the Nose, .....555 10. Of the Cerumen of the Ear, ..... ib. 11. Of the Humours of the Eje,.....556 12. Of the Liquor of the Pericardium, *. . . 557 13. Of Sinovia,...........ib. 14. Of Urine, ...........558 15. Of Sweat,...........563 16. Of Semen,...........565 17. Of Milk, ...........ib. 18. Of the Liquor of the Amnios,.....569 CONTENTS. HI. Morbid Products, .........569 Sect. 1. Of Pus,............ib- 2. Of the Liquor of Dropsy,......571 3. Of the Lh)uor of Blisters,......572 4. Of Concretions of Phosphate of Lime, . . ib. 5. Of Biliary Concretions, ......570 6. Of Urinary Concretions,......57-t 7. Of Gouty Concretions,.......581 Chap. HI. Reflections upon the Chemical Constitution of the Human Body,.........583 Chap. IV. Of Animal Functions, elucidated by Che- mistry,.............588 Sect. 1. Of Respiration,..........589 2. Of Secretion and Assimilation, . . . .594 Chap. V. Of the Decomposition of Animal Bodies after death,............600 ERRATA. Page 11, line 22, for much stronger, read not nearly so stron ■•■ 66, 3, zirconium, read zirconia. 159, 23, pelalile, read petalite. A SYSTEM OF CHEMISTRY STUDENTS OF MEDICINE. IT is proposed, in the present work, to take such a view of Plan of the the science of Chemistry, as will mark, more particularly, its work' numerous relations to that of Medicine. Accordingly, while the whole ground which the science embraces will be gone over, so as to make the work complete in itself; those par- ticular portions of it only, the knowledge of which is abso- lutely essential to the formation of a medical education, will be particularly dilated upon, and the practical details connected with them carefully noted. In a complete system of chemistry, the subject naturally what a divides itself into two parts: one in which the science, complete strictly so called, is detailed; the other, in which all the braces. substances in nature, within the reach of the chemist, are examined, and the facts connected with them recorded: this second part of the subject has been very properly called a chemical examination of nature. But in the present work, this arrangement will be con-In what the siderably modified. In the first part, the science of chemistry, Pres and or practising medicine, will be but cursorily noticed; while oAhTdif- of others, such as of many of the salts, metals, acids, &c. ference. substances which constitute important parts of the materia medica, the chemical history will be more fully given. In the second part, instead of taking a view of the whole of nature, a chemical examination will be made of the atmosphere and waters of the. globe, and of vegetable and animal substances generally, closing with a particular ac- count of the animal chemistry of the human body. A [ 2 ] PART I. SCIKNCE OF CHEMISTRY. With what 1 HE science of chemistry is concerned in noticing those phenomena actlons 0f matter upon matter, which take place at insensible of^hemis* distances. This branch of knowledge may be very naturally try is con- divided into two parts; the first giving a history of the cerne ' changes produced upon bodies, as consequences of these actions; and the second, detailing the laws by which the Division 0facti°ns themselves are regulated. The first part may be this part of called a chemical account of bodies: the second treats of the the subject, attraction of aggregation and chemical affinity. The various bodies which are presented to the observation of the chemist differ in a certain particular, which makes it convenient to describe them in two distinct sets. One set are capable of being estimated by weight; the other set, comprising light and heat, are imponderable. The latter, having many common properties, are described with great propriety by themselves; and being more difficult to under- stand than the ponderable bodies, it is proper to postpone their consideration until the substances which may be es- timated by weight have been disposed of. Agreeable then to the foregoing view of the subject, the science of chemistry, properly so called, will be treated of under the three following heads, forming the subjects of as many books: I. Ponderable bodies, II. Imponderable bodies, III. The general properties of matter upon which chemical changes depend. [ 3 ] BOOK I- OF PONDERABLE BODIES. ALL the bodies which are included under this title may Book 1. be separated into certain constituents, which resist the Ponderable efforts of further analysis. Although it is demonstrable thatches simple substances must exist in the nature of things; yet it is by no means certain, that those at present undecompound- ed are really simple. In fact the large number of such bodies, at present reckoned by chemists, is rather unfavourable to the opinion. These constituents, therefore, of ponderable bodies will be denominated undecompounded bodies; the epithet undecompounded expressing the bare fact only that such bodies have never been resolved into simpler consti- tuents___Now all the ponderable bodies must be either unde- are either compounded, or bodies known to be compound. Accordingly, "^Sded;" on this basis, the ponderable bodies will be arranged into two or known sets under the title of divisions; namely, p°ound!°m 1. Undecompounded ponderable bodies. 2. Compound ponderable bodies. DIVISION I. OF UNDECOMPOUNDED PONDERABLE BODIES. In conformity with Dr. Thomson's arrangement, these Division of ... .,,,/.• i i • the unde- bodies will be divided into compound- 1. Supporters of combustion, ed ponder- « r u ..-ui able bodies. 2. Incombustibles, 3. Combustibles. The substances arranged under each of these heads, will be treated of in the three following chapters. After the consideration of the undecompounded pondera- ble bodies has been thus completed, the arrangement of them which has been adopted will be explained and illustrated; and then the theory of definite proportions in chemical combination, and the atomic theory, will be noticed. These two subjects will be given in a fourth and fifth chapter, as they will form a very proper sequel to the chapters employed in describing the chemical bodies in- cluded in the present division. 4 UNDECOMPOUNDED SUPPORTED. Book I. Division I. CHAPTER I. OF UNDECOMPOUNDED SUPPORTERS OF COMBUSTION. Term sup. The term supporter is applied to those bodies, whose porter ex- preScnce is absolutely necessary in every case of combus- Pla,ned' tion: the undecompounded supporters are those bodies of 'this kind which have never been decomposed. The undecompounded supporters are reckoned as three; they are the following: 1. Oxygen, 2. Chlorine, 3. Iodine. The substance called fluorine is supposed to have most of the properties of an undecompounded supporter. But its title to a place in this class of chemical bodies is founded, for the most part, upon analogical reasonings; and until its real nature is more accurately developed, it is better, with- out classing it, to describe its properties, as far as they are known, at the end of the present chapter. The supporters above enumerated will constitute the sub- jects of the three following sections. SECTION I. OF OXYGEN* GAS. Hephlogisticated Air of Priestley. Method of L Oxygen gas may be obtained by the following process: obtaining Putinto a flask a quantity of the black oxide of manganesef, XJgen" a substance to be described hereafter, and pour upon it a portion of oil of vitriol, sufficient to form it into a thin paste. Fit to its mouth a glass tube, bent in the shape of the • From o^oT»f acidity, and yiyvofiat to generate. f It is imp< ssiblc. from the i.atuie of the science of Chemistry, to commence with any part of it, so completely elementary, as not to require the introduction of other parts to aid in explanation. From this fact, it becomes necessary, at 'he very threshold of the work, to intro-mce substances to the notice of the" reader, of which lie is presume'! to have no knowledge This being an inevitable diffi- culty, the reader is advised, whenever he meets with a new term, to consult the index of the wo k. in order that ht- may refer to the chemical substance which such term is intended to convey, and thereby acquire some idea of its nature. OXYGEN. 5 etter S. Adjust the mouth of the tube so as* to be in the Chap.i. proper relative position to the pneumatic apparatus*, pre--------- viously prepared with an inverted jar filled with water. Apply heat to the flask by means of a lamp or candle. An air will be perceived passing up in bubbles into the inverted jar: this air is oxygen gas. II. The rationale of the formation of oxygen gas by the Expiana- above process appear to be this: the oil of vitriol dots nottionofthe i-i m i i 1 1 • i r u process. dissolve easily, the black oxid- ct manganese; but veryr readily the green oxide of this substance, which contains only half as much oxygen as the black. Accordingly the oil of vitriol, by its action upon the black oxide, displaces half its oxygen which appears in the gaseous form, and, after be- ing reduced to the state of green oxide, dissolves it. III. Oxygen gas was first obtained by Dr. Priestley in Discovery. 1774: it was afterwards discovered by Scheele before he had any knowledge of the previous discovery of Priestley. IV. Oxygen gas is a colourless and elastic fluid like Properties. common air. It is entirely destitute of taste or smell. V. Bulk for bulk, it is a little more than one and one- Spec. grav. tenth times as heavy as atmospheric air. 1108- VI. Oxygen gas supports flame with greater vividness, Oxygen and for a longer time than atmospheric air. If a burning supports body be introduced into a glass vessel containing this gas, its flame is increased exceedingly in brilliancy. The products of combustion in this gas are called oxides. It supports re- and respi- spiration, and animals live longer in it than in an equalratI0n" bulk of atmospheric air. The consideration of its uses, however, both in combustion and in respiration, will be de- ferred until these subjects come to be treated of particularly. VII. Oxygen gas is a constituent in atmospheric air, of Composes* which it forms in bulk a little more than one-fifth part. It Part of the is also a constituent of water, forming eight-ninths of that and°of wa* liquid by weight. ter. • * This apparatus consists of a trough of wood, generally lined with sheet lead or tin, in which a shelf is fitted, about three inches from the top. In the shelf, a hole or slit, about an inch in diameter, is made. When used, the trough is filled with water to about an inch above the surface of the shelf; a glass vessel filled with water and inverted is then placed upon it, over the hole or slit: now if the beak of a retort or the extremity of a glass tube be plunged into the trough, so that its mouth shall be under this opening; any air or gas which may be forced through either, will ascend through the opening in the shelf into the upper part of the vessel, inverted upon it, displacing, at the same time, the water. In this manner the gases which are not absorbed, or very sparingly so, by water, are preserved. Any gas which is taken up largely by water, is collected by a similar apparatus in which quicksilver is substituted for water. 6 UNDECOMPOUNDED SUPPORTERS Book I. Division I. ------ SECTION II. OF CHLORINE* GAS. Dephlogisticated Muriatic Acid of Schcch'i—O.nigenized Muriatic Acid ol Berthollet. Method of I. Chlorine gas may be obtained by the following pro- obtaining cess: put }nto a small glass retort a quantity of the black gas"™ oxide of manganese in powder, and pour upon it a sufficient quantity of the marine acidf of the shops, to convert it into a thin paste. Plunge the beak of the retort into a pneumatic trough, and apply the heat of a lamp to its bottom. A gas is extricated, which may be collected in inverted glass phials, in a manner similar to that described in the last section. The phials may be removed from the trough, and the gas preserved by fitting to their mouths accurately ground stoppers. This gas is chlorine. Expiana- II. Chemists have ascertained that the marine acid is a tion of the compound of the gas under consideration, and an inflamma- ble air to be described hereafter under the name of hydro- gen. In the process just given, the acid and the oxide mu- tually decompose each other; the chlorine of the former is extricated while its hydrogen combines with the oxygen of the latter. Chlorine III. Chlorine gas was discovered by Scheele in 1774. b'HTheef- *n 1785' Berthollet made a set of experiments upon it, by ' which he was supposed to have proved it to be a compound of the marine acid and oxygen. In 1809 Gay-Lussac and Thenard published some experiments going to demonstrate that oxygen could not be shown to exist in Berthollet's true nature oxygenized muriatic acid. Sir H. Davy soon after took up hTsi °H ^e SUDJect' anc^ ln two PaPers which were published in the Davy. Philosophical Transactions for 1810, fully demonstrated that all the experiments which were supposed to indicate the compound nature of oxymuriatic acid, as the gas under consideration was then called, were fallacious; and in fact that it was as yet an undecompounded substance: he ac- cordingly changed its name to chlorine. Properties. IV. Chlorine is in the form of a gas, and possesses the mechanical properties of atmospheric air. Its colour is greenish yellow; its smell, very strong and suffocating, exactly like that produced upon mixing together aqua fortis * From %\ughc green. | An acid which may be obtained from common salt by the action of the oil of vitriol, to be described hereafter. CHLORINE. 7 and the marine acid. It destroys all vegetable colours, Chap. i. changing them to white. V It is nearlv two and a half times as heavy as atmos- Spec. grav. ... J 2-4700. phenc air. VI. Chlorine gas supports combustion. Some of the Supports metals, as antimony, arsenic, zinc and iron, take fire spon- combustlon taneously when plunged into it. The products of these combustions are compounds formed of the burning body and chlorine: they are called by chemists, chlorides. VII. Chlorine gas does not support respiration. An ani- but not re- mal forced to breathe it, dies almost instantly. From this spira it appears, that chlorine, although it agrees with oxygen in supporting combustion, is very different from the latter in being unrespirable. VIII. Chlorine gas is absorbable by water, with which Absorbable it forms a liquid having the characteristic properties of the by water- gas itself. When fully saturated, water contains twice its volume of chlorine. IX. Chlorine combines in four proportions with oxygen, Forms four and forms compounds, which have been distinguished by °°Kxy.ds the following names: gen. 1. Protoxide* of Chlorine. 2. Deutoxide of Chlorine. 3. Chloric acid. m 4. Perchloric acid. • Chloric and perchloric acids will be described hereafter under the head of acids; the latter under the changed name of oxychloric acid. The oxides of chlorine will be noticed this place. 1. Protoxide of Chlorine may be obtained by distilling at l. Protox- a gentle heat, the substance formerly called hyperoxymuriate l^°£ chI°" of potash, but at present more properly named chlorate of potashf, mixed with a small proportion of marine acid. A gas is extricated which must be received over mercury. This gas is the protoxide of chlorine. The rationale of its formation is not very obvious. * Oxide is the term applied to all substances of two ingredients, of which Oxygen is one, unless such substances have acid, alkaline, or earthy properties. When oxygen combines in two proportions with a body, without the appearance of these properties, the oxides formed are distinguished by the prefixes proto or prot, abbreviated from xqurot first, and deuto or deut, from JWtfo? second; the former being applied to the oxide which contains the least oxygen, the latter to the oxide which contains the most. When a greater number than two oxides of the same substance are to be distinguished, other prefixes derived from the Greek numerals are employed. This mode of distinguishing oxides was de used by Dr. Thomson. ■j" Chlorate of potash is prepared by passing a current of chlorine gas through a solution of common potash, until the latter becomes saturated. The liquid thus formed, upon standing deposites crystals of chlorate of potash. It is a com- pound of chloric acid and potash, and will be described hereafter. 8 UNDECOMPOUNDED SUPPORTERS. Book I. 2. This gas was discovered in 1811 by Sir H. Davy, by Division * whom it was named euchlorine; but its present name, given by Dr. Thomson, is preferable, being expressive of its com- position. Properties. 3. Protoxide of chlorine has an intenselv yellow colour, and a smell resembling that of burnt sugar. It destroys ve- getable blue colours, but not until after it has given them a tint of red. Spec. grav. 4. It is somewhat less than two and a half times as heavy 2-407 i as atmospheric air. 5. It is absorbable by water. This liquid when fully sa- turated, contains eight times its bulk of the gas, and pos- sesses its peculiar colour and smell. Composi- 6. Protoxide of chlorine is composed of tion' Chlorine 36 Oxygen 8 44 2. Deutox- 1. Deutoxide of Chlorine may be obtained by the following ide of chlo- process: Tike a very sm til quantity of chlorate of potash (the same substance which is employed in the formation of the protoxide of chlorine) ind form it into a dry paste by mixing it with oil of vitriol. Put this paste into a small retort, and immersgits belly in hot water, whose temperature must not be allowed to reach the boiling point. A gas is immediately extricated, which must be collected over mercury. This gas is deutoxide of chlorine. 2. Deutoxide of chlorine was discovered about the same time by Sir H. Davy and Count Von Stadion. Properties. 3. It has a bright yellowish-green colour, and a peculiar aromatic smell. Spec. grav. 4. It is about two and one-third times as heavy as com- 23 l' mon air. 5. It exerts no action upon any of the combustibles except phosphorus. This substance, when introduced into it, pro- duces an explosion, and burns with gn-at brilliancv. 6. Water absorbs seven times it bulk of this gas. The solu- tion has a deep yellow colour, and an astringent corrosive taste. Composi- 7. Deutoxide of chlorine is composed of tl0n- Chlorine 36 Oxygen 32 68—so it appears that -this oxide of chlorine contains four times as much oxygen, CHLORINE. 9 united to the same quantity of chlorine, as the one last Chap, t. described. X. The property which chlorine possesses of destroying Chlorine all vegetable colours, suggested its use to Berthollet as an jJJ^> agent in bleaching. Accordingly it is used extensively for that purpose, wherever bleaching is carried on largely. XI. Chlorine is found to be a most efficacious agent in and in des«. destroying contagion and putrid exhalations of all kinds. ^gJJ^ It is at present in general use in the anatomical theatres and putrid both of Europe and America, and in the naval and military miasmata: hospitals of Great Britain. In order to prepare this gas for the purpose of destroying contagion or miasmata of any kind; all that is necessary is to mix together two parts of common salt and one of the black oxide of manganese; and to pour upon the mixture two parts of oil of vitriol: the fumes of chlorine immediately arise and are distributed in the infected atmosphere with the effect of destroying the miasmata. XII. Chlorine gas produces very striking effects upon the and as a human system. When taken internally, or when externally remedy. applied in solution by sponging or in the form of a bath, it very soon creates uneasiness in the throat upon swallowing, a redness of the gums, and a burning sensation over the roof of the mouth. These effects are succeeded by the for- mation of little ulcerated specks, which penetrate the cuticle only, on the inside of the mouth and tongue; but fetid ul- cerations, such as are formed by the use of mercury, are never produced. When employed extr rnally the teeth par- take of the uneasy feeling of the mouth, but are in no case injured. All these effects are very fugitive, passing away in some cases in a very few days. On the general system it has the effect of quickening the pulse. It appears to act with considerable energy upon the glandular system. Of all the glands in the body, it appears to exercise the greatest influence over the liver, increasing the secretion of bile in an eminent degree. It is to Dr. H. Scott particu- larly that the medical world is indebted for having first pointed out the effects of chlorine in the diseases of the liver. This physician was in the habit of using it as a remedy in the hepatitis of India, which according to him is a mixture of the acute and chronic states of that disease. In such cases he has found chlorine to be equallv efficacious with the oxides of mercury, without its use being attended with the disagreeable, and sometimes injurious, effects of the latter remedies. To those cases of derangement of the biliary sys- tem, which are accompanied by uneasy nervous feelings, he B UNDECOMPOUXDKD SUPPORTERS. found the use of this supporter particularly suited, by un- clogging the vessels of the liver and calming the nervous sysu-m. . Dr. Scott compares the remedial powers of chlorine to those: of mcrcurv; but attributes to tie former the advan- tage of being harmless as a remedy, even in unskilful hands. It is particularly suited, according to him, to those cases of disease, which appear to require mercury; but which, oc- curring in peculiar or delicate constitutions, forbid the use of that remedy. Chlorine is spoken of as a remedy also in syphilis; but the experience of its use in this disease has not been sufficiently diversified to afford conclusions to be depended upon. Dr. Scott uses the remedy internally; and also externally, in the form of a bath, by sponging, and by immersion of different parts of the body. Dr. Scott makes his bath of a mixture of equal parts of marine acid and nitrous acid*, diluted with water until its acidity is about equal to that of weak vinegar. He prepares it warm and directs its use once a day, continuing each bathing half an hour. When used internally, Dr. Scott directs the mixture, ren- dered very weak by dilution, to be taken in small quantities at a time during the day, using the precaution of washing the mouth after each dose. It is presumed that as much of the mixture may be taken through the course of a day as may be conveniently swallowed. Water saturated with chlorine was found by Dr. Scott to have the same effects as a remedy as his preparation of mixed acids. This physician therefore does not hesitate to believe that chlorine is the active part of his remedy; and in accordance with this opinion, the same medical proper- ties attributed by Dr. Scott to his acid mixture, have in the present section been assigned to chlorine. | • An acid to be described hereafter, which, by mixture with marine acid, extricates chlorine. j See Dr. Scott's paper on the internal and external use of the nitro-muriatic acid in the cure of diseases, from which the above facts are taken; republished in the Med. Recorder, Vol. 1. p. 81. IODINE. 11 Chap. I. SECTION III. OF IODINE.* I. Iodine may be obtained by the following process: Iodine.how Digest a quantity of kelpf in water, until every thing solu- PrePar8d ble is taken up. Filter the solution and evaporate it until all the common salt, which will fall, has separated in crystals. Boil the residual liquor with a portion of oil of vitriol for some time. Put the liquid thus formed into a small retort, and add as much black oxide of manganese as had pre- viously been employed of oil of vitriol. If heat be applied to the liquid after this addition, a violet coloured vapour arises, which by condensation in a proper receiver is con- verted into a brilliant solid substance. This substance is ■<; iodine. II. Iodine was discovered in 1811 by Courtois, a salt- Discovery. petre manufacturer of Paris. Very little progress, however, was made in the investigation of its properties until the winter of 1813-14, when it received a particular examina- tion from Gay-Lussac and Thenard, and Sir H. Davy. III. Iodine is a solid substance of a greyish black co- Properties. lour, and possessing the metallic lustre. Its smell is similar to that of chlorine but much stronger. Its taste hot, and acrid, leaving a lasting impression on the mouth. Like chlorine it destroys vegetable colours. IV. Iodine in the solid form is nearly five times as heavy Spec. grav. as an equal bulk of water. In a state of vapour it is more as * 9°'ld than eight and a half times as heavy as atmospheric air. Its as vapour melting point is at the temperature of 224|°. 8 C78- V. If a piece of phosphorus be thrown upon a quantity of iodine, the two substances unite rapidly with the evolu- tion of a great deal of heat, but no light is visible. The compounds formed between iodine and combustibles or incombustibles are called iodides. Iodine supports the com- bustion of several of the combustibles as will be seen here- after. VI. Water dissolves not more than ToVartn Part °f its weight of iodine, and acquires an orange yellow colour, and the smell of iodine, but no taste. VI I. Iodine combines in one proportion with oxygen Combines forming iodic acid, and in one proportion with chlorine, wltn °*J' forming what has been called the chloriodic acid. The con- chlorine. • From louinf, violet coloured. \ Kelty is ashes of certain sea plants, which are burnt on account of the soda which they yield. Y2 UNDECOMPOUNDED SUPPORTERS. Book I. sideration of these compounds will be defered until the Piv'gion L class of acids come to be treated of. Has no VI11. Iodine has never been applied to the purposes of uses. medicine. But from the experiments of Orfila, who ascer- tained it to possess very active, and in large doses, poisonous properties, there is reason to hope that it may become hereafter a very useful article of the materia medica. SECTION IV. OF FLUORINE. Fluorine, I. This name has been given by Sir H. Davy to a sub-. the nnme stance< tne existence of which he has rendered very proba- foTthebase ble, although the body itself has never been obtained in a of the acid SCparate state. It is necessary to notice the reasonings upon spar"°r which the belief of its existence is founded in this place; as the substance, so far as its nature has been inferred, ap- pears to bear a close resemblance to the supporters. whichthere H» 1* is tne supposed base of the acid of fluor spar, is reason which it is considered to form in combination with hydrogen. fng isepecu-Thc facts wnich lead to this opinion of the nature of the liar in its acid of fluor spar are strong though not decisive. For ex- nature, ample, if this acid, perfectly free from water, is brought in contact with potassium (the metallic base of the vegetable alkali potash) a violent action takes place, hydrogen is emitted, and a solid white substance is formed. Now the inference drawn from this experiment is that the compound formed is made up of a constituent of the acid of fluor spar, unknown m the separate state, and potassium; and that the hydrogen emitted had been previously united to this pecu- liar radical, constituting the acid. Several experiments of a similar kind to that above stated, have strengthened the sup- position that the acid of fluor spar contains a radical of a peculiar nature; but all attempts heretofore made to obtain it in a separate state have proved unsuccessful. These facts are stated merely to give the reader some idea of what is known concerning this hypothetical substance. AZOTE. |3 Chap. II. CHAPTER II. OF UNDECOMPOUNDED INCOMBUSTIBLES. An incombustible may be dtfined, a body which is Definition eapable, neither of supporting- combustion, nor of undergo- °£mabnus£' ing that process. But one undecqrapounded body, answer- ble. ing to this definition, is known. It is called azote, and will be described in the following section. SECTION I. QF AZOTE.* Nitrogen gas of Chaptal.—Phlogisticated air of Priestley. I. This gas may be obtained by the following process: Azote: ho\r Put a mixture of iron filings and sulphur, moistened byobtained- water, in a small plate, under a glass vessel, containing air and placed over water. Let the apparatus stand in this state for a few days, and it will be found that part of the air has disappeared, and that the space, which it had previously occupied, is filled with water. The air which remains is azote. II. To understand the above process, it is necessary for Process the reader to know that atmospheric air is composed of exP,aine(I« the gas under description and oxygen. By the exposure of a portion of atmospheric air in close vessels to the influence of a moistened mixture of iron filings and sulphur, that part of it which consists of oxygen is absorbed, while its azotic portion remains behind. III. Azotic gas was discovered in 1772, by Dr. Ruther- Discovery. ford of Edinburgh. IV. It is a gaseous fluid, having all the mechanical pro- Properties, perties of atmospheric air. It has neither taste nor smell. V. It is not quite so heavy as atmospheric air, compared Spec grav. with that gaseous fluid, bulk for bulk. °'978- VI. It is not fit to carry on the process of respiration. Unfit to Animals forced to breathe it die as they would from suf- suPP°.rt re- c .. . . . . , J , spiraUon, location. Neither is it fit to support combustion; no com- or combus- bustible substance will burn in it. tion- * From k privatire of, and f«» life. 14 UNDECOMPOUNDED INCOMBUSTIBLES. Book I. VII. It is scarcely absorbable by water; unless this li- Divisiool. guid be freed from the air which it usuany contains by boil- ing; in the latter case it is taken up in small quantity. Combines VIII. Azote is capable of uniting with oxygen in five ^inV" ProPortions and forms compounds which have received proportions the following names: 1. Protoxide of azote (nitrous oxide) 2. Deutoxide of azote (nitrous gas). 3. Hyponitrous acid.* 4. Nitrous acid. 5. Nitric acid (aqua fortis). The two first named only of these compounds will be described in this place; the three last, having acid proper- ties, will be described under the head of acids. i.Protox- 1. Protoxide of azote, the dephlogisticated nitrous gas How^Te^ of Dr. Priestley, may be obtained by the following pro- pared, cess: Expose dry nitrate of ammoniaf to the heat of a lamp, in a retort adjusted to a mercurial trough. A gas is immediately extricated. This gas is the protoxide of azote. Discovery. 2. Protoxide of azote was discovered in 1776 by Dr. Priestley. Spec grav. 3. It has all the mechanical properties of atmospheric air. 152- It is very little more than one and a half times as heavy as common air. Supports 4. It supports combustion. Bodies burn in it with nearly oombustion: the same brilliancy as in oxygen gas. When respired it ces singular produces very extraordinary effects, which have some re- effects semblance to those arising from intoxication. Animals breathed forced to breath an atmosphere composed of this gas, die after the lapse of some time. 5. It is absorbable by water. This liquid when fully sa- turated contains somewhat more than three-fourths of its bulk of the gas. Composi- 6. Protoxide of azote is composed of Azote 14 Oxygen 8 22 * The characteristic termination of the name of an acid compound, is in ic. When several acid compounds are formed from the same ingredients united in different proportions, the termination in ic distinguishes the name of that one which contains the largest proportion of oxygen; the termination in out is ap- propriated to the name of the one which contains the next largest quantity. If a third acid compound formed of the same ingredients exist, containing oxygen in a still smaller proportion, the name by which it is known ends in ous also, but is distinguished from that of an acid containing oxygen next in degree to the highest, by the prefix hypo, derived from the Greek uVe under. f A substance to be described hereafter. Hon AZOTE. 15 7. From the very powerful effects produced by the Chap. II. protoxide of azote when respired, there can be little doubt that it might be used very advantageously in some dis- eases, by respiration. But although many of the pneumatic medicines produce valuable effects upon the human consti- tution, yet their expensiveness will alwrays prevent them from coming into general use. 1. Deutoxide of azote or nitrous gas may be obtained 2. Deutox. by the following process: Pour the aqua fortis of the shops ^t°f. how upon a quantity of copper filings placed in a retort. The obtained. filings are rapidly dissolved, and a gas is extricated, which may be collected in glass vessels over water. This gas is deutoxide of azote. 2. Aqua fortis is composed of azote united to the Explana- largest quantity of oxygen with which it is capable of com-t,onofth* bining: when poured upon copper filings, part of its oxygen is abstracted, by combining with them, and what remains continuing to be united to the azote, forms the gas in question. 3. Deutoxide of azote was accidentally discovered by Discovery. Dr. Hales, but its properties were first investigated by PriesUey. 4. It is an invisible and elastic fluid. It is very little Spec grav. heavier than atmospheric air. It supports the combustion of some combustibles, but not of others. A lighted taper introduced into it goes out; sulphur is also extinguished even when introduced burning with a white flame; but it supports the combustion of phosphorus with great bril- liancy. 5. When employed in respiration, it proves exceedingly Noxious in noxious. Animals forced to breathe it become immediately respiration. suffocated. 6. Water previously freed from air, absorbs about one- tenth of its bulk of this gas. The solution formed has no taste, and is incapable of reddening vegetable blues. 7. Whenever the deutoxide of azote comes in contact Effects of with atmospheric air, the latter is decomposed, and the mix-tts- ™ixine ture assumes a yellow colour. The oxygen of the atmos- pheric ai?" pheric air combines with the deutoxide and forms the acid called nitrous acid, which gives rise to the yellow colour just mentioned. If the experiment be made in glass ves- sels over water, a very considerable condensation will be observed; this arises from the absorbability of the product (nitrous acid) by water. The residual gas after the con- densation is complete is azote. The same acid is formed 16 UNDECOMPOUNDED INCOMRUSTIBLES Book I. when the deutoxide of azote is mixed with oxygen gas Division I. -m do9e vesstis. but in thls case, there is no residual gas. Composi- 8. Deutoxide of azote is composed of tion- Azote 14 Oxygen 16 30—so it appears that this oxide of azote contains twice as much oxygen as the protoxide last described. Azote, a IX. Azote in combination with oxygen gas, together constituent witn moisture and a very small proportion of carbonic acid, pheriTaTr. constitutes the atmosphere which surrounds the globe. The atmosphere will be treated of hereafter in a separate chapter; it is only mentioned in this place incidentally, in order to complete the account of the different combinations of azote and oxygen. Chloride of X* Azote has the property of combining with chlorine, azote. and forming a compound called chloride of azote. How pre- *• This chloride may be prepared by the following pro- pared, cess: Place a solution, not quite saturated, of nitrate of ammonia in a flat dish. Invert over it a glass jar containing chlorine. The gas is slowly absorbed, and there collects on the surface of the solution an oily substance, which gra- dually sinks to the bottom: this oily substance is the chloride in question. Discovery. 2. Chloride of azote was discovered in 1812 by Dulong. P erties 3" *' 's a transparent liquid, of a colour very like that of ' olive oil. Its smell is strong and peculiar. It is extremely volatile. When exposed to the temperature of 212°, it explodes with prodigious violence. Great caution is neces- sary in its preparation, owing to the last mentioned property; and, when experimented upon, larger quantities than a grain should not be employed. Spec. grav. 4. Chloride of azote is somewhat more than one and 1.653. a half times as heavy as water. It is not capable of solution in water; but when it is mixed with that liquid, it is decomposed, its chlorine dissolves, while its azote is li- berated.—The composition of this chloride has not been exactly ascertained. XI. Azote combines in one proportion with iodine, azote? ° forming the compound called iodide of azote. 1. This iodide may be prepared by putting a quantity of tion. iodine in a solution of ammonia:* the iodine is converted * Ammonia is the substance which causes the odour of hartshorn. One of- its constituents is azote. It will be described hereafter. UNDECOMPOUNDED COMBUSTIBLES. 17 into a blackish brown powder, constituting the iodide Chap. m. under consideration. It was discovered by Courtois. "------— 2. It is very volatile; fl\ ing off in vapour, without leav- Prepar- ing any residuum, when exposed to the open air. It detonates ties- violently when heated, or even when slightly touched, and azote and iodine are formed. The proportion in which its constituents are united is not ascertained. XII. The foregoing are all the compounds which azote is capable of forming with the substances already described; its combination with other substances will be mentioned under the heads of such substances respectively. XIII. Azote has never been applied to any medical or Azote is economical use. applied to CHAPTER III. OF UNDECOMPOUNDED COMBUSTIBLES. Bt combustibles are meant, bodies whose combination Definition with supporters is attended by the emission of sensibk light of a.00"*- and heat. In the present chapter it is proposed to treat of those bodies answering to this definition, which have never been resolved into simpler constituents. The undecompounded combustibles will be divided into Undecom- four classes, characterized as follows: pounded I. Undecompounded combustibles which act the part of D°™j"vided an acidifying body. Combustibles of this class will be called into acidifying combustibles. At present there is but one bodv -1' Acidlf}- i li • i • i • • ii j . 7 J lnScom- known belonging to this class; it is called hydrogen. bustibles. II. Undecompounded combustibles which are capable of 2. Acidifia- forming acids, but not salifiable bases, by combining with tibeie£mbur' oxygen. Combustibles of this class are, 1. Carbon; 2. Boron; 3. Phosphorus; 4. Sulphur; 5. Arsenic; 6. Chromium; 7. Molybdenum; 8. Tungsten; 9. Columbium; 10. Selenium. These will be called acidifiable combustibles. III. Undecompounded combustibles, which form com-3. Interme- pounds with oxygen, capable of performing the part of {Ji*ujbc.om- acids or salifiable bases, under different circumstances, in the formation of neutral salts. These are, 1. Antimony; 2. Tellurium. These bodies will be called intermediate combustibles. IV. Undecompounded combustibles which form salifiable bases-, but in no instance acids, by combining with oxygen. Such combustibles will be distinguished by the name basi- C 18 ACIDIFYING COMBUSTIBLES. Book I. fiable* combustibles. This class will be divided into three Pivisionl sub-classes. 4. Biisifia- 1. Combustibles forming, with oxygen, salifiable bases biecnm. which h;ive alkaline properties. These will be called al- whShWml kahfiable combustibles: they are, 1. Potassium; 2. Sodium; are divided 3. Lithium; 4. Calcium; 5. Barium; 6. Strontium; 7. Mag- in three sub-classes. Uesium. 2. Combustibles forming, with oxygen, salifiable bases, which have earthy properties: these are, 1. Yttrium; 2. Glucinum; 3. Aluminum; 4. Zirconium; 5. Thorinum; 6. Silicum. 3. Combustibles forming, with oxygen, salifiable bases, which have neither alkaline nor earthy properties: these are, 1. Iron; 2. Nickel; 3. Cobalt; 4. Manganese; 5. Cerium; 6. Uranium; 7. Zinc; 8. Lead; 9. Tin; 10. Copper; 11. Bis- muth; 12. Mercury; 13. Silver; 14. Gold; 15. Platinum; 16. Palladium; 17. Rhodium; 18. Iridium; 19. Osmium; 20. Titanium. CLASS I. OF ACIDIFYING COMBUSTIBLES. Acidifying Tins class of undecompounded combustibles will be completed by the accoui.t of hydrogen in the following section. combusti bles. SECTION I. OF HYDROCEN.t (Formerly called Light Inflammable Air.) Hydrogen; I. Hydrogen may be obtained by the following process: tainedb ^ut one Part °^ *ron ^nSs *n a retort, having an opening in its upper and convex part, just over the containing cavity: such a retort is called tubulated by chemists^ Pour upon the filings two parts of oil of vitriol, previously diluted with four times its bulk of water, through the opening just described, and then close it. A quantity of air immediately rushes out of the mouth of the retort; but being impure by admixture of atmospheric air, must • I make no apology for forming this adjective to distinguish this class of combustibles. It is sufficient lor my purpose that it expresses very well the idea intended to be conveye.l. and supersedes the necessity of circumlocution. t From vtug water, and ytywpeu to generate. HYDROGEN. 19 not be collected for some moments. As soon as this impure Ghap. m. air has passed out, adapt the retort to the pneumatic appa-------— ratus, and collect the gaseous product in jars over water. The product is hydrogen gas. II. In explaining this process, it is necessary to inform Process ex- the reader that water is composed of ox\ gen and hydrogen P,ained- chemically combined. Now the water with which the oil of vitriol is diluted is decomposed; its oxygen unites with the iron and forms an oxide, while its hydrogen is evolved. III. Some of the properties of this gas were noticed in Discovery. the last, and even in the seventeenth, century; but very little was known respecting its nature, before Cavendish distinguished it from atmospheric air, and noted most of its properties. IV. Hydrogen gas is an invisible and elastic fluid, like Proper- common air. When perfectly pure, it is destitute of smell. ties- V. It is the lightest body at present known; it is about Spec. grav. one-fourteenth as heavy as common air. '0732. VI. It does not support combustion. All burning bodies Extinguish- are extinguished when plunged into it. es flame» VII. Respiration cannot be carried on by its means, and is unfit Animals forced to breathe it expire as they would from |?r resPira- _ v J tion. suffocation. VIII. Hydrogen is not sensibly absorbed by water, unless this liquid be previously freed from air by boiling. IX. If a lighted taper be brought to the mouth of a phial How it containing hydrogen, it takes fire, and burns, when pure,burns- with a yellowish white flame. X. Hydrogen unites with oxygen in one proportion only, Combines and forms the compound called water. The combination is wlth.ox7- ^cn in one always attended by combustion; and the heat produced is proportion more intense than that generated by any other substance °nlv» and while undergoing the same process. Taking advantage of ter: this fact, Dr. Hare, of this city, many years ago, contrived an instrument which enables the experimental chemist to avail himself, in his researches, of the intense heat thus ge- nerated. This instrument has since been employed in Great Britain without acknowledgment. Water is too important a compound to be cursorily described under the head of hydrogen: it will therefore be considered hereafter in a separate chapter. It is proper, however, to notice the proportion in which its constituents combine. It is composed of Hydrogen 1 Oxygen 8 9 20 Book I. Division I. with chlo- rine in one proportion only, form- ing hydro- chloric acid: and with io- dine in one proportion, forming hy- driodic acid Combines with azote in one pro- portion on- ly, forming ammonia. ACIDIFIABLE COMBUSTIBLES. XL Hydrogen combines in one proportion only with chlorine, and forms the marine acid, or, as it is generally called, muriatic acid. The compound deserves very particu- lar attention, and will be treated of hereafter, under the name of hydrochloric acid. XII. It combines also in one proportion with iodine, and forms an acid called hydriodic acid. This compound will be noticed hereafter, under the head of acids. XIII. By the hvpothetical composition of the acid of fluor spar, as has been already mentioned, hydrogen is con- sidered as one of its constituents, existing in a state of combination with a peculiar substance, proposed to be called fluorine. Although the composition of this acid is involved in great doubt, vet the compound itself is of considerable importance, and will be described hereafter under the name of hydrofluoric acid. XIV. Hydrogen combines in one proportion only with azote, and forms the compound called ammonia. It is usually distinguished by the names of hartshorn and vola- tile alkali. It will receive a separate consideration hereafter. Acidifiable combusti- bles. CLASS II. ACIDIFIABLE COMBUSTIBLES. The acidifiable combustibles are: 1. Carbon; 2. Boron; 3. Phosphorus; 4. Sulphur; 5. Arsenic; 6. Chromium; 7. Molybdenum; 8. Tungsten; 9. Columbium; 10. Selenium. These bodies will be noticed in the ten following sections. Charcoal how obtain' ed. How pre- pared for the arts. SECTION I. OF CARBON, (Common name Charcoal.) I. Charcoal may be obtained in the following manner: Expose a piece of wood placed in a crucible* and covered with sand, to a red heat for some time. The wood will be converted into the substance called charcoal. II. Charcoal is prepared, to be used in the arts, in the following manner: A number of billets of wood, stripped of their bark, and about four feet long and five or six inches thick, are piled on their ends in a conical form. The pile is then covered with clay, except at certain places, through * A pot made of black lead or earth, in which fusions are generally made- CARBON. 21 which the fire is applied. The pile smokes in consequence Chap. III. of the slow combustion which is going on; and in two or three days it is uncovered, and the charcoal raked out of the ashes. III. Charcoal is a black shining brittle substance, some- Properties. what sonorous when struck; and when pure, destitute of taste or smell. It is insoluble in water, and infusible in the highest heats that can be raised. It is somewhat less than Spec. grav.. half as heavy as water. °'**L IV. The diamond chemically considered is nearly the Chemically same as charcoal. It is the hardest and most splendent of ^j^8*™^ the precious stones. It has heretofore been found only in diamoud. India and Brazil. At a mean, it is about three and a half times as heavy as water. V. When heated to the temperature of 800° in the open During air, charcoal combines rapidly with oxygen; the chemical combustion action being attended by all the phenomena of combustion, with oxy- The product is a gaseous acid, which is called carbonic acid. &en; It will be noticed hereafter, under the head of acids. ductPIcar- VI. Besides carbonic acid, charcoal forms another com tonic acid. pound with oxygen. It is in the gaseous form also, and is Combines called carbonic oxide. dose of"* 1. Carbonic oxide may be obtained in the following man- oxygen, ner: Expose a mixture of equal parts of iron filings and^™^ chalk, made as dry as possible, in an iron retort, to a red oxide: heat. A great quantity of gas is extricated. Agitate the gaseous product with lime-water, which absorbs a part of it: the residue is carbonic oxide. 2. In explaining this process, it is necessary to inform the reader, that chalk is a compound of carbonic acid and lime. Now carbonic oxide contains less oxygen Jian car- bonic acid. In consequence of the heat to which the mixture is exposed, the filings are capable of abstracting a portion of oxygen from the carbonic acid of the chalk; whereby the acid is reduced to the state of carbonic oxide. The oxide, however, is not extricated pure by the above process; it always has mixed with it a portion of carbonic acid. This is removed by the agitation with lime-water, by which it is absorbed. 3. Dr. Priestley was the first chemist who distinguished Discovery. carbonic oxide as a peculiar gas; but Cruickshanks first ascertained its real composition. 4. Carbonic oxide is an invisible and elastic fluid like Properties. atmospheric air; and very nearly of the same weight. Spee. grav. 5. It is capable of undergoing combustion. When set 0956. on fire, it burns with a lambent blue flame, emitting very little light. During the combustion it combines with an 22 Book I. Division I. Unfit to be respired. Combines with chlo- rine and forms an acid. Forms a gaseous compound with hy- drogen. Composi- tion. ACIDIFIABLE COMBUSTIBLES additional dose of oxygen, and the product is carbonic acid. • i i j 6. It is unfit for supporting respiration. Animals placed in an atmosphere of this gas, drop down dead almost instantly. 7. Carbonic oxide has the property of combining with chlorine, and forms a compound, having acid properties. It will be described hereafter under the name of chloro- carbonic acid. 8. Carbonic oxide is capable of forming a gaseous com- pound with hydrogen. This gas was lately discovered by Dr. Thomson while experimenting upon the ferrocyanate of potash, commonly called triple prussiate of potash. It is formed by the action of oil of vitriol upon the above men- tioned substance by the assistance of heat. It has a peculiar, but not a disagreeable smell, and an aromatic taste, attended by a hot impression upon the mouth, which continues for some time. It is not absorbable by water. It burns readily, when brought in contact with a candle, with a deep blue flame. It is very little lighter than atmospheric air.* 9. Carbonic oxide is composed of Carbon 6 Oxygen 8 Carbon combines with azote and forms cyanogen: how obtain- ed. Discovery. Properties. Spec. grav. 1-80. Both a sup- porter and a combusti- ble. 14 VII. Carbon combines with azote and forms the com- pound called cyanogen. 1. Cyanogen may be obtained by exposing the substance usually called prussiate of mercury,f in a dry state, to a heat rather under redness, in a small retort. It blackens, and a gas is extricated which must be collected over mer- cury. This gas is cyanogen. 2. Cyanogen was discovered in 1815, by Gay Lussac. 3. It is an invisible and elastic fluid like common air. Its smell is peculiar, strong and disagreeable. It is about one and four-fifth times as heavy as common air. 4. Although a compound of an incombustible and a com- bustible, this gas is nevertheless a supporter of combus- tion. It supports the combustion of potassium. On the other hand it is a combustible. The products of its com- bustion are carbonic acid and azote. 5. It possesses the singular property of combining with * See a paper by Dr. Thomson, on triple prussiate of potash. Annals of Philosophy, xii. 102. f This substance will be noticed hereafter. CARBON. 23 several combustibles, and even with some salifiable bases, Cbap. hi. without undergoing decomposition. These compounds, when Forms cya- they do not possess acid properties, are called cyanodides. nodides. Some of them will be noticed hereafter. 6. Cyanogen is composed of Carbon 12 Azote 14 26 VIII. Carbon combines with hydrogen in two propor- Carbon tions, and forms compounds, which have been named by forms two " ' ii r i i i -i. i f compounds Dr. Thomson hydroguret ot carbon and binyclroguret ot with hydro- carbon. Sen- 1. Hydroguret of carbon, formerly called defiant gas, l. Hydro- may be obtained by applying the heat of a lamp to a mix- j^^f ture of four parts of oil of vitriol and one part of strong spirit of wine: the gas in question is immediately disen- gaged, and may be collected in jars over water. 2. This gas was discovered in 1796, by the associated Discovery. Dutch chemists. 3. It is an invisible and elastic fluid, destitute of taste or Properties. smell. It is very little lighter than common air. It burns Spec. grav. with splendour, the products being carbonic acid and water. Q$7*5- It is absorbable by water, which liquid when saturated contains one-tenth of its bulk of the gas. 4. Hydroguret of carbon combines with chlorine, and Combines forms a compound which Dr. Thomson proposes to call ™*e for^. chloric ether. It may be obtained by making a current of ing chloric the two gases meet in a large glass receiver. A chemicaletIier- union immediately takes place, and the compound in ques- tion collects at the bottom of the receiver. It is a limpid and colourless liquid like water, possessing a peculiar sharp sweetish agreeable taste, and in smell resembling the ether formed from hydrochloric acid (marine acid). It is a little Spec grav. more than one and one-fifth times as heavy as water. It 12201- burns with a green flame, vapours of hydrochloric acid (marine acid or muriatic acid) being formed, together with much soot. When passed through a red hot porcelain tube it is decomposed into hydrochloric acid, and a gas com- posed of hydrogen and carbon; while charcoal is depo- sited. 5. Hydroguret of carbon is composed of Composi- Carbon 6 tion of the hydrogu- Hydrogen 1 ret. 7 24 ACIDIFIABLE COMBUSTIBLES. Book I. Division I. 2. Bihydro- guret: how obtained. The same as the fire- damp. Spec. grav. 0-555. Composi- tion. Nature of heavy in- flammable gas. 1. Bihydroguret of carbon, usually called carburetled hy- drogen, may be obtained in the following manner: Attach a piece of wood to an inverted glass jar in such a way as to cause it to float on water with its mouth a little below the surface; being at the same time filled with water. Place the glass jar thus prepared upon the surface of a stagnant pond, and stir up the mud at the bottom, just under its mouth; a number of air bubbles will ascend into the jar and displace the water. This gas, after being washed with lime- water to separate carbonic acid, is pure bihydroguret of carbon. 2. Bihydroguret of carbon is the gas which forms in coal- mines, distinguished by the name of fire-damp, and which has occasioned such fatal consequences to miners by its explosions. 3. Bihydroguret of carbon is an invisible and elastic fluid, destitute of taste or smell. It is somewhat more than half as heavy as common air. When set on fire, it burns with a yellow flame; the products of the combustion are water and carbonic acid. 4. It is composed of Carbon 6 Hydrogen 2 8—so that it appears that this* gas contains twice as much hydrogen as the simple hydroguret; and hence the reason that it is distinguished from the latter by the prefix bi, contracted from the Latin word bis, twice. IX. The inflammable gases, which are obtained by the distillation of moist charcoal, pit-coal, or wood, are found to be mixtures, in different proportions, of hydrogen, hvdro- guret and bihydroguret of carbon, and carbonic oxide. From the constituents of these gases varying continually, according to the substances from which the distillation is made, the degree of heat, and the stage of the process at which they may be collected, there is reason to believe that none of them are chemical compounds, but chemical mix- tures only. X. The gas obtained from pit-coal and from tar is now employed both in Europe and America for the purposes of illumination. Dr. Thomson ascribes the merit of the sug- gestion of gas-lighting to Mr. Murdoch of Birmingham. The gas from pit-coal is found to be a compound of hy- droguret and bihydroguret of carbon mixed with carbonic oxide. BORON. 25 XI. Charcoal has been used with several views in medi- Chap, hi. cine. At one time it was given internally in consumption as Medical a deoxidizing remedy, under the influence of the theory, JjJJjJj. that this disease depended upon the superoxygenation of the blood. It has been recommended very highly for the cure of intermittent fever. Its antiseptic powers make it a proper ingredient in poultices for gangrene, and sloughing or fetid ulcers. The same power renders it one of the best tooth powders that can be used, more especially for carious teeth. SECTION II. OF BORON. I. Boron may be obtained by the following process: Boron; Expose equal parts of boracic acid,* obtained as pure as h°we?b'" possible, and potassium, placed alternately in a copper tube, for some minutes, to an obscure red heat, in a small furnace. Upon withdrawing the heat, there is found in the tube an earthy looking matter, which must be treated with water, until every thing soluble be taken up: the residue, after being washed repeatedly, until the water comes off unaltered, is to be dried in a capsule at a moderate heat: it is now pure boron. II. Boracic acid is a compound of the substance under Expiana- description and oxygen. Potassium is an ingredient in the tion oftlie ■ DTOC6SS vegetable alkali potash, and is found to have a very strong tendency to combine with oxygen. Now this substance com- bines with the oxygen of part of the boracic acid, and be- comes converted into pure potash; while the peculiar sub- stance called boron is liberated from combination. Part of the potash formed remains pure, and part combines with the boracic acid not yet decomposed, forming the compound called borate of potash. Upon washing the product, these latter substances, being soluble, are removed; and what re- mains when dried is pure boron. III. Although Sir H. Davy had reason to believe that Discovery. he had decomposed the boracic acid, when he exposed it to the action of galvanic electricity in 1807; yet the discovery of boron belongs to Gay-Lussac and Thenard, who were the first chemists who put its existence beyond doubt, by decomposing boracic acid, and afterwards recomposing it from its constituents. • Boracic acid is s sour substance obtained by decomposing borax, 26 ACIDIFIABLE COMBUSTIBLES. Book I. Division I. Proper- ties. Phenome- na attend- ant on its combus- tion: product, an acid. Combus- tion in chlorine uncertain. It combines with fluo- rine, and forms an acid. IV. Boron is a brownish-green solid, destitute of taste, and producing no effect upon vegetable blues. It is infusible and not volatilizable at a very intense heat. It is insoluble in water, alcohol (strong spirit of wine), ether or the oils, whether hot or cold. Its specific gravity has not been accurately ascertained. V. Upon exposure to a cherry red heat in the open air, boron takes fire, and burns for some time. Its surface, by the absorption of oxygen, is converted into boracic acid, which vitrifies by the heat, and thereby puts a stop to the combustion. The crust of acid thus formed may be dissolv- ed off, and what remains is boron, not yet acted upon. By alternate combustions and solutions, the whole of the boron may be converted into boracic acid. From this statement thv.* inference may be drawn, that boron, during combustion, combines with oxygen and forms boracic acid. The account of this acid will be deferred until the class of acids come under consideration. VI. According to Gay-Lussac and Thenard, boron does not burn in perfectly dry chlorine; but according to Sir H. Davy, it burns in this supporter with a brilliant white flame. VII. Boron combines with the radical of the acid of fluor spar, or fluorine, and forms an acid compouad, which wUl be treated of under the head of acids. SECTION III. Phospho- rus; how obtained. OF PHOSPHORUS. I. Phosphorus may be obtained by the following process: Mix 100 parts of calcined or burnt bones, reduced to fine powder, and diluted with four times their weight of water, with 40 parts of oil of vitriol, in a porcelain or stoneware basin: the mixture grows hot, and a number of air-bubbles escape. Stir the mixture occasionally, and at the end of twenty-four hours, pass it through a filter of linen cloth. Calcined bones are composed of a sour compound (consist- ing of phosphorus and oxygen, and called phosphoric acid) united with lime. The oil of vitriol, by its action, has the ef- fect of detaching from combination with the phosphoric acid, nearly all the lime; with which it forms a compound which renders the mixture turbid, it being of an insoluble nature. By throwing the whole upon a linen filter, the PHOSPHORUS. 2f insoluble compound is retained, while a transparent liquid, Chap.iD:. consisting of phosphoric acid combined with a small portion of lime and dissolved in water, passes through. The next step in the process is to add gradually to the liquid thus obtained, a solution of the nitrate of lead (a compound of nitric acid (aqua fortis) and oxide of lead) as long as any white powder is thrown down: the consequence of this ad- dition is, that the nitric acid combines with the lime, which it holds in solution; while the oxide of lead unites with the phosphoric acid, and falls in the form of an insoluble powder. This insoluble compound of phosphoric acid and oxide of lead, called by the chemists phosphate of lead, must be separated by the filter, washed, and dried. Then mix it with one-eighth of its weight of charcoal powder, and expose it gradually, by means of a furnace, to a white heat in an earthenware retort, whose beak is plunged under water. For some time bubbles t.f air, which occasionally inflame, break from the surface of the water; at a particu- lar temperature, the phosphate of lead becomes decomposed; the charcoal abstracts all the oxygen which it contains, and flies off in the form of carbonic acid;* so that nothing is left but lead and phosphorus. The lead remains in the retort in. a state of fusion, while the phosphorus is driven forward in the state of vapour, and drops from its beak into the water. II. Phosphorus was accidentally discovered by Brandt, aits discove- chemist of Hamburgh, in 1669, while attempting to extract j7 and from human urine a substance capable of converting silver into gold. In 1674, it was again discovered by Kunkle, a German chemist, although all he knew of Brandt's process was the animal fluid which was employed in it. Boyle, by his own account, also discovered phosphorus, and communicated his process to his assistant, Godfrey Hankwitz, a London apothecary, who continued for many years to supply all Europe with this substance. In 1<737, a person appeared in Paris who asserted that he could make phosphorus. Several members of the French academy witnessed his process, for communicating which he was rewarded by the French government. It was a very tedious one, consisting in evaporating putrid urine, and produced only small quantities of phosphorus at a time. Soon after this period, Margraff published a more expe- ditious process for obtaining phosphorus, which consisted in mixing inspissated urine with a salt of lead. In this way * The reader is presumed to know the constituents of carbonic acid, they having been given under the head of Charcoal, p. 21. 28 ACIDIFIABLE COMBUSTIBLES. Book I. he proved that urine contained a substance, which, when Dlvia<"1 L mixed with charcoal, produced phosphorus. Exists in The next step in the investigation of phosphorus was the b0ne8, discoverv of its existence in bones, made by Gahn. This was followed by Scheele's inventing a process by which phosphorus might be obtained from these animal substances. Proper- III. Phosphorus is a white substance; and, when per- Ue8- fectly pure, is transparent and nearly colourless; but as usually procured, it is of a bright amber colour, and semi- transparent. After having been kept for some time under water, it assumes the appearance of white wax. When heated to the temperature of 148°, it takes fire, burning with a very bright flame. By combustion in atmospheric air or oxygen gas, it is converted into an acid compound called phosphoric acid. By mere exposure to the air, it undergoes a kind of slow combustion; and an acid com- pound is formed, which is now generally considered to be a mixture of phosphoric acid, and another acid of phos- phorus called phosphorous acid. Spec. grav. IV. Phosphorus is a little more than one and three-fourth .1-770. times as heavy as water. Its melting point is at the tempe- rature of 108°. When air iafexcluded, it evaporates at 219*, and boils at 554°. Combines V. Phosphorus combines with oxygen in four propor- with oxy- tions, and forms compounds which are distinguished by the gen in four c ,. . * ° J propor- following names: tions. Oxide of phosphorus. Hypophosphorous acid. Phosphorous acid. Phosphoric acid. The three last mentioned compounds being acids, their description will be deferred until the class of acids come to be treated of. The oxide of phosphorus will be noticed in this place. Oxide of 1. Oxide of phosphorus may be obtained in the following phospho- manner: Expose a small quantity of phosphorus to the heat obtained. OI" boiling water in a long narrow tube; a white vapour arises, and condenses on the inside of the tube: this consti- tutes the oxide in question. It contains less oxygen than the acid compounds of phosphorus and oxygen: its properties have not been ascertained. Phosphorus VI. Phosphorus combines in two proportions with chlo- S>rmpoinds rine' and f?rms compounds distinguished by the names of with chlo- protrochloride and perchloride of phosphorus. iinproto- 1' PrQtochloride of phosphorus is obtained by passing chloride: the vapour of phosphorus through heated corrosive subli- how ob- mate (a compound of chlorine and mercury) in a glass or PHOSPHORUS. 29 porcelain tube, to one end of which a receiver is luted. A Chap. hi. liquid collects in the receiver, which consists of this proto- chloride. 2. This chloride was first made in quantities and exa- Discovery. mined by Gay-Lussac and Thenard; but its real constituents were first demonstrated by Sir H. Davy. 3. Protochloride of phosphorus is a colourless liquid, of Properties. an acid and very caustic taste. It smokes strongly in the open air; but in close vessels it remains unaltered. When dropped into water, this liquid is decomposed, and its con- stituents uniting to the constituents of the chloride, form hydrochloric (muriatic) acid, and phosphorous acid. It is Spec. grav. nearly one and a half times as heavy as water. l 45- 4. Protochloride of phosphorus is composed of Composi- Phosphorus 12 tion- Chlorine 43* (nearly) 55 1. Per chloride of phosphorus may be obtained by burn-2. Perchlo- ing phosphorus in dry chlorine gas. obuunedW 2. It is an exceedingly volatile substance of a snow- Properties. white colour. Its vapour reddens litmus paper; from which it would appear that it possesses acid properties. It decom- poses water with great energy, and combines with its con- stituents in such a way as to form hydrochloric (muriatic) acid, and the phosphoric acid. Although a product of com- bustion, it is still capable of undergoing that process; when in the form of vapour, it burns, when lighted, in the open air. 3. Perchloride of phosphorus is composed of Composi- Phosphorus 12 tion- Chlorine 80* 92.—So that it appears that this chloride contains somewhat less than twice as much chlorine as the protochloride. VII. Phosphorus combines in two proportions with Phosphorus iodine, and forms the compounds called by Dr. Thomson,forms tw0 • ,. . . . ,. , JT . . _,/ . .. , 'compounds protiodide and periodide ot phosphorus. 1 hese iodides were with iodine. first noticed by Sir H. Davy; but Gay-Lussac was the first chemist who subjected them to an accurate examination. 1. Protiodide of phosphorus may be formed by mixing i. Protio- dide: how ' formed. • The above analysis does not accord with the theory of definite proportions. Hereafter every analysis, which is at variance with this theory, until the reader is made acquainted with it, will be distinguished by an asterisk. This mark of distinction the reader will find convenient when he comes to apply the theory. 3Q ACIDIFIABLE COMBUSTIBLES. Book i. together in a glass tube, 1 part of phosphorus, and 10*41 Division I. parts 0f iodine; the combination takes place rapidly with the evolution of much heat, but no light. Properties. 2. It is a solid substance of a reddish-brown colour. Its melting point is at the temperature of 212°. When thrown into water, it decomposes that liquid, and at the same time is converted into hydriodic acid and phosphoric acid. Composi- 3. Protiodide of phosphorus is composed of tion. Phosphorus 12 Iodine 125 137 8. Perio- 1. Periodide of phosphorus may be prepared by mixing db[e- 'd* toSet^er 1 Part 0mP phosphorus and 20-82 parts of iodine; they combine with violence and with the evolution of a great deal of heat. Properties. 2. It is a solid substance of a black colour. Its melting point is at the temperature of 115°. It dissolves in water with the evolution of much heat; being at the same time decomposed. f;°™p0SI* 3* Periodide of phosphorus is composed of Phosphorus 12 Iodine 250 tion. 262—so that it appears that the periodide contains exactly twice as much iodine as the protiodide. Phosphorus VIII. Phosphorus dissolves in small proportion in dissolves in azote# The combination is attended by a small increase of azote. J bulk. Effects of IX. Phosphorus may be melted and sublimed in protox-' protoxide j^g Qf azote (nitrous oxide) or even touched while in that it; gas with a red hot iron, without alteration; but if a wire heated to whiteness, be presented to the phosphorus, it takes fire and explodes; the products being azotic gas, and nitric and phosphoric acids. and of chlo- X. Phosphorus, brought in contact with chloride of azote, nde of explodes violently. It has not been possible to collect the products. Forms two XI. Phosphorus combines in two proportions with hy- wiu\PhUdro- drogen, anc* forms compounds, which Dr. Thomson calls gen. hydroguret and bihydroguret of phosphorus. l. Hydro- 1- Hydroguret of phosphorus, or phosphuretted hydrogen guret of as it is usually called, may be obtained in the following man- rus°how ner: Throw into a small retort, filled with water acidulat- obtained. ed with hydrochloric (muriatic) acid, a portion of the com- pound formed of phosphorus and lime, which has been PHOSPHORUS. 31 carefully secluded from the air; a quantity of gas is imme- Chap, hi. diately extricated, which must be collected over water. This gas is the hydroguret of phosphorus. 2. Hydroguret of phosphorus was discovered in 1783 by Discovery. Gengembre, while heating a mixture of liquid potash and phosphorus in a small retort. 3. It is in the form of a colourless and elastic fluid. Its Properties. smell is similar to that of onions; its taste exceedingly bit- ter. It is somewhat lighter than atmospheric air. When it Spec grav. comes in contact with common air, it takes fire sponta- °9022- neously and burns with great splendour. In chlorine gas it burns with a greenish yellow flame; the products being hydrochloric (muriatic) acid and chloride of phosphorus. Water saturated with it contains rather more than two per cent.; and acquires a yellow colour, an intensely bitter taste, and a smell similar to that of the gas. 4. Hydroguret of phosphorus is composed of ComposI- Phosphorus 12 tion- Hydrogen 1 13 1. Bihydroguret of phosphorus may be obtained by ex- Bihydrogu- posing hydroguret of phosphorus to the action of the direct rfJXho^ rays of the sun: phosphorus is thereby deposited and the gas is converted into this hydroguret. 2. Bihydroguret of phosphorus was first particularly ex- amined in 1812, by Sir H. Davy, by whom it was obtained by exposing crystallized phosphorous acid to heat. 3. It is in the form of a colourless and elastic fluid. Its Properties. smell is similar to that of hydroguret of phosphorus, but not so disagreeable. It is very nearly as heavy as atmos- pheric air. It does not burn spontaneously in atmospheric air or oxygen gas; but when heated to the temperature of 300° in either of them it explodes, the products being wa- ter and phosphoric acid. When mixed with chlorine, a spon- taneous combustion takes place, attended with a white flame. The products are hydrochloric (muriatic) acid and chloride of phosphorus. It is absorbable by water, which when sa- turated contains one-eight of its bulk of the gas. 4. Bihydroguret of phosphorus is composed of Composi- Phosphorus 12 tion. Hydrogen 2 14.—-So that it appears that the bihydroguret contains twice as much hydrogen as the hydroguret. 32 ACIDIFIABLE COMBUSTIBLES. Book 1. 5. Mr. Dalton does not admit of the existence of this on L hydroguret. This chemist considers that there is but one dWdb6 combinati°n °f phosphorus and hydrogen; and that, the one Dahon. 7 which has just been described under the name of hydrogu- ret of phosphorus; that when it is obtained from phosphuret of lime, which has been exposed even for a few.hours to the atmosphere, it is liable to be more or less contami- nated with free hydrogen; and that the bihvdroguret of phosphorus is hydroguret of phosphorus, mixed with a variable quantity of free hydrogen.* Combus- XII. Phosphorus is a very combustible substance. When tion(* heated to the temperature of 148°, in the open air, it com- phospho- .. .,, . ,r , . ..* 111 rus: bines rapidly with oxygen; the action being attended by a vivid combustion. Under such circumstances, phosphorus product, combines with the largest dose of oxygen with which it is phosphoric capable of uniting, and forms the acid called phosphoric acid, already mentioned. Medical XIII. Phosphorus has never been used extensively in properties medicine; and vet, from its active properties, there is rea- of phospho- . ' •, . • , , r 1 • rus. son to believe, that it might be very useful in many cases of disease. When taken in the dose of from one-eighth to one-fourth of a grain, rubbed up with some mucilage of gum arabic, it produces great heat about the stomach, and occa- sionally violent purging. It has been used in France, as well as in this country, as a stimulant in low fevers; but it would appear that the success was not very encouraging. In debility of the sexual organs, it it said to have been used with advantage. The effects of this substance upon the system deserve to be particularly investigated. It is not important to know in what diseases it has been tried; but if a complete history of its effects was made out, it would enable practitioners to know what results they had a right to expect from it, and to use it accordingly. SECTION IV. OF SULPHUR, (Commonly called Brimstone.) Sulphur: I. Sulphur may be easily obtained by distilling the mi- tamed^ neral called pyrites.f It rises in a state of vapour, and may be made to deposite in proper receivers. In this state it is called flowers of sulphur. * See Dalton on Phosphuretted Hydrogen. Thomson's Annals, xi. 7. f Metallic combinations, containing a very large proportion of sulphur. SULPHUR. 33 II. Sulphur is found native abundantly, especially in the Chap. hi. neighbourhood of volcanoes. III. It is a hard brittle substance of a greenish yellow Properties. colour, without any smell, but possessing a weak taste. It remains unchanged in the open air, and is insoluble in water. IV. It is nearly twice as heavy as water. Its melting Spec. grav. point is at the temperature of 218°. l"°- V. When heated in the open air to the temperature of Itscombus- 560°, a rapid combination with oxygen takes place, attend- ^ej!s" ed by all the phenomena of combustion; while at the same time, fumes of a suffocating odour are emitted. The flame is of a pale blue colour. If the combustion be performed in pure oxvgen, the product is found to be an acid, which is product an called bv chemists the sulphurous acid. Besides this acidRC1 ' formed by combustion, sulphur forms with oxvgen two other acids, which are called hyposulphurous and sulphuric acids. The last mentioned acid, in common language, is called oil of vitriol. These acid compounds will be describ- ed hereafter under the head of acids. VI. Sulphur combines in one proportion with chlorine, Forms one and forms chloride of sulphur. wZchh?- 1. Chloride of sulphur may be obtained by passing a cur- rine. rent of chlorine through flowers of sulphur; or by heating Chloride °* sulphur in a dry glass vessel containing chlorine. how obtain- 2. It is in the form of a liquid, of a brownish red colour «!■ or of a yellowish green, according as it is viewed by re- roper ie fleeted or transmitted light. Its smell is strong and some- what similar to that of sea plants. Its taste is acid, hot and bitter, affecting the throat with a painful tickling. It smokes very much in the open air; and the eves when exposed to its vapour, become filled with tears, and'are affected with that smarting sensation, produced by smoke. It changes the co- lour of moist litmus paper to red. It is about one and Spec. grav. three-fourth times as heavy as water. l'7, 3. Chloride of sulphur is composed of Compost- Sulphur 16 tion- Chlorine 36 52 VII. Sulphur combines in one proportion with iodine, Forms one and forms iodide of sulphur. witKmi 1. Iodide of sulphur may be easily formed by mixing together its constituents, and exposing them to a heat suf- ficient to melt the sulphur. 2. It is of a greyish black colour, and radiated struc- ture. It was first described by Gay-Lussac. E 34 ACIDIFIABLE COMBUSTIBLES. Book I. VIII. Sulphur combines in two proportions with hydro- p»i«on_L gen< and forms compouncis, which are generally known by Sulphur t"he names of supersulphuretted hydrogen, and sulphuretted compounds hydrogen. Sulphuretted hydrogen possesses all the proper- with hydro-ties of an acid; while the supersulphuretted hydrogen has gen; the characteristic property of that class of chemical bodies, which are in as much as it forms compounds analogous to salts with to adds"8 salifiat)k bases. Both these compounds will be described among the acids, under the names of hydrosulphurous and h) drosulphui ic acids. and one IX. Sulphur combines with carbon, and forms the com- 3Trn-d Pound c^led sulphuret of carbon. hon. ' 1. Sulphuret of carbon may be obtained by the following Sulphuret proceS8. piace a porcelain tube, filled with charcoal, through of carbon; r r ' . . •» i howobtain-a lurn.ice, fixed in an inclined position. Lute to its lower ed- extremity a glass tube of such a shape that it may be passed into a bottle of water; to the other end, lute another glass tube, containing bits of sulphur, and furnished with a wire fixed in such a way as to admit of being used to push the sulphur forward, without admitting the air. Heat the charcoal to redness, and continue it at that temperature, until bubbles of air cease to be disengaged;- then push the sulphur by means of the wire into the porcelain tube. A substance will pass into the bottle and condense under the water: this substance is the sulphuret of carbon. Properties. 2. Sulphuret of carbon is a transparent and colourless liquid, of an acrid, pungent and somewhat aromatic taste; and nauseous, fetid, and quite peculiar smell. It is one of the most volatile liquids known. It was first obtained in 1796 by Lampadius, upon distilling a mixture of pyrites and sulphur. This chemist supposed it to be a compound Spec. grav. of sulphur and hydrogen. It is somewhat more than one 1-272. anci one-fourth times as heavy as water. Its boiling point is between the temperature of 105° and 110°. It does not con- geal when cooled down to — 60°. It produces a greater cold by its evaporation, than any other substance known The mercury in a thermometer, whose bulb is enveloped in fine lint wetted by it, sinks from 60° to about zero. In a re- ceiver of an air pump, which is rapidly exhausted of air, a thermometer under the same circumstances sinks to — 82° in the course of a few minutes. When raised to a certain temperature in the open air, it burns with a blue flame: the products being sulphurous acid, carbonic oxide and car- bonic acid. ARSENIC. 35 3. Sulphuret of carbon is composed of Chap, hi. Sulphur 32 Composi- Carbon G tion- 38 X. Sulphur combines with phosphorus, and forms sul- Sulphur phuret of phosphorus. This sulphuret is readily formed by 5|Jh,plJJg. melting its constituents together under water. The heatphorus. must be applied cautiously. The constituents of this sulphu- ret unite in various proportions. XI. Sulphur furnishes the physician with a very valuable Sulphur, laxative. It appears particularly suited for haemorrhoidal ^j^g. affections. In psora, when mixed with some mild ointment, it constitutes one of the best external applications. SECTION V. OF ARSENIC. I. Arsenic may be obtained pure by the following pro- Arsenic; cess: Expose a mixture of two parts of white arsenic (ajj^ed. compound of oxygen and arsenic) with one part of black flux,* to a gentle heat; the flux separates the oxygen from the white arsenic, which is thereby reduced to a state of purity, and then slowly sublimes. II. Arsenic, generally combined with sulphur or oxygen, Where is found principally in Germany. It has been found intound- some parts of the United States; combined with iron near Boston; with nickel in Maryland; and with cobalt in Con- necticut.! III. It is a metallic substance of a bluish white colour Properties. and considerable brilliancy. When cold it has no smell; but when heated it emits an odour resembling that of garlic. It is the softest of all the metals; and so brittle that it may be reduced to powder in a mortar. When exposed to the air, it loses its lustre, turns black and falls to powder; but un- der water it remains unaltered. IV. It is somewhat less than eight and one-third times Spec. grav. as heavy as water. Its fusing point is not known, in conse- 8-31- quence of its subliming before fusion. * Flux is a term applied to substances, used by chemists to facilitate the fusion of metals, or the reduction, to the metallic state, of metallic ores. The black flux is made by detonating one part of nitre and tv o parts of tartar together in an ignited crucible. f See Cleaveland's Mineralogy. 36 ACIDIFIABLE COMBUS'l IBL1 ■'..•>. Book I. V. Arsenic burns with a pale blue flame. The product Division I. 0f the combustion is an acid. Forms two VI. Arsenic combines in two proportions with oxygen, Poundsm" and forms compounds having acid properties. They are with oxy- called by chemists the arsmious acid and arsenic acid. The Ben- former is that which is formed during combustion; they will be described hereafter under the head of acids. Forms one VII. Arsenic combines in one proportion with chlorine, v/iuTc°hlod and forms chloride of »rsenic- rine.C ° 1. Chloride of arsenic, formerly called butter of arsenic, Chloride of mav De obtained by distilling a mixture of six parts pf cor- oEnedh°Wroe'ive sublimate (a chloride of mercury) and one part of arsenic, with a gentle heat; the chloride in question passes over, and may be collected in a receiver. Properties. 2. Chloride of arsenic is a volatile transparent liquid of the consistence of oil. It is decomposed by being mixed with water; arsenious acid being prccipitattd. Arsenic VIII. Arsenic combines with iodine and forms iodide of Vith^ocfine arser»ic It may be prepared by bringing its constituents into 'contact, whereupon they unite readily. This iodide is of a dark purple red colour. It possesses acid properties. and with IX. Arsenic has the property of combining with hydro- hydrogen. gen^ an(j forms the compound called arsenuretted hydrogen. Arsenarct- 1. Arsenuretted hydrogen may be obtained very readily genhVhov°' by pouring sulphuric acid (oil of vitriol) diluted with twice obtained, its weight of water, upon a mixture of four parts of zinc and one of arsenic: a gas is immediately extricated. This gas is arsenuretted hydrogen. It becomes formed in consequence of the decomposition of water; the hydrogen of that liquid, just at the moment of its formation, comes in contact with the arsenic and dissolves it in minute proportion. Properties. 2. Arsenuretted hydrogen is a colourless and elastic fluid like common air. Its smell is nauseous. When drawn into the lungs it produces very deleterious effects. It is capable of combustion. When set on fire, it burns with a blue flame. It was discovered by Scheele during his experiments upon arsenic. Arsenic X. Arsenic has the property of combining with phos- with phos- ph°i"t>s, forming the compound called phosphuret of arsenic. phorus; It may be obtained by distilling a mixture of equal parts of its constituents over a moderate fire. This compound has a brilliant appearance and a black colour. It requires to be kept under water for preservation. and with XI. Arsenic combines with sulphur and forms sulphuret sulphur. 0f arsenic. Sulphuret 1. This sulphuret may be obtained by melting together of arsenic. jts constituents in a covered crucible. When thus formed CHROMIUM 3_ it is usually called realgar, and is a solid substance of a Chap. hi. scarlet colour, about three and one-third times as heavy-------- as water. It has no taste. This same sulphuret may be formed also by pouring a solution of hydrosulphuric acid (sulphuretted hydrogen) into a solution of arsenious acid in hydrochloric (muriatic) acid. It falls in the form of a powder of a fine yellow colour. In this state the sulphuret is usually called orpiment. 2. Sulphuret of arsenic occurs native both in the form of Found ua- realgar and of orpiment. Native orpiment however is nottive- in powder, but composed of thin plates which possess some degree of flexibility. XII. Arsenic, in the metallic state, 'ias not been applied Metallic to any medical use; but the acids which this metal furnishes arsen.ic not are very powerful articles of the materia medica. dicme? ™ SECTION VI. OF CHROMIUM.* I. Chromium may be obtained by the following process: Chromium; Take two parts of the mineral called chromate of iron, which howobtam- consists of an acid of chromium combined with an oxide ofe iron, and expose it, mixed with one part of nitrate of pot- ash (nitre), to the action of a strong heat. By this means, part of the mineral will be decomposed. Digest the mass thus altered in water, until every thing soluble is taken up. Separate this solution and set it aside; it contains nothing but chromic acid. Treat the residue, left after the action of the water, with hydrochloric (muriatic) acid, which will dissolve off the oxide of iron, which had been previously combined with the separated chromic acid. What remains now of the mass is nothing but the undecomposed chromate. By repeating the treatment just detailed a number of times, the mineral is at last totally decomposed. This being ef- fected, mix all the aqueous solutions of the chromic acid together, and saturate the whole by means of nitric acid (aqua fortis). This latter acid combines only with the chro- mic acid, without uniting to impurities, and may be made to crystallize in this state of combination. Separate the crystals of the combined acids, dissolve them in water, and mix the solution with a solution of nitrate of mercury, a • From xfifia. colour; because it has the property of giving colour to other bodies in a remarkable degree. 38 ACIDIFIABLE COMBUSTIBLES. Book I. compound formed of nitric acid and oxide of mercury. The Division L chromic acid immediately separates the nitric acid of the nitrate, combines itself with the oxide of mercury, and in this state precipitates in the form of chromate of mercury. Expose the chromate of mercury, after being well washed, to a strong heat in a stone-ware retort. The mercury is thereby volatilized, and nothing remains but pure chromic acid. Expose the chromic acid mixed with charcoal to a strong heat in a porcelain furnace. The charcoal combines with the oxygen of the acid, flying off in the form of carbo- nic acid; while the pure chromium remains behind. How found II. Chromium in its pure state has never been found na- m nature. t-lve. but aerified anrl combined with oxide of lead it oc- curs in Siberia, under the name of the red lead ore of Siberia. The chromate of iron has been found in France, and abundantly near Baltimore in the United States. Discovery. HI. In 1797 Vauquelin ascertained the true nature of the red lead ore of Siberia, by discovering that it contained a metallic body previously unknown. To this metallic body, he gave the name of chromium. Properties. IV. Chromium is a brittle metal, of a white colour, in- termediate between that of tin and steel. It is capable of being polished. It is not altered when exposed to air, but becomes oxidized when subjected to heat. Acids act upon it with great difficulty. Spec. grav. V. It is somewhat less than six times as heavy as water. 5'90, It requires a very high temperature to bring it into a state of fusion. Forms VI. Chromium combines with oxygen in three propor- three com- tions, and forms compounds which are called protoxide of oxvgen;one chromium, deutoxide of chromium, and chromic acid. The of which is jast named compound will be described under the head of an acid. • j acids. l.Protoxide 1. Protoxide of chromium may be prepared by exposing oxideCen chromic acid to heat in close vessels. Oxygen gas is driven off and the acid is reduced to the state of this oxide. It has a green colour. It is very soluble in acids, but is not capa- ble of forming salts by combining with them. Its exact composition has not been determined. 2. Deutox- 2. Deutoxide of chromium may be prepared by dissolv- 'oxide1'™"™"1^ l^e Protoxide in nitric acid (aqua fortis), evaporating the solution to dryness, and exposing the dry mass to heat until it cease to emit nitrous fumes. It is a brown brilliant powder, scarcely soluble in potash or soda. It is totally in- soluble in acids, and consequently incapable of forming any salt. MQLYBDENUM. 39 Ghat. HI. SECTION VII. OF MOLYBDENUM.* I. Molybdenum may be obtained by the following pro- Moiybde- cess: Roast the mineral called molybdena, which is a sul- obumedW phuret of the metal under consideration, slowly and repeat- edly at a moderate red heat, until it is reduced to the state of a fine powder. By this treatment the sulphur is driven off, and the metal is oxidized. In order to separate any im- purity, dissolve the powder in pure ammonia, filter the so- lution thus formed and evaporate it to dryness. The am- monia dissolves the oxide alone, leaving the impurities; and when the solution is evaporated to dryness, the ammonia is is driven off, and nothing remains but pure oxide of molyb- denum. Mix the pure oxide thus obtained with some char- coal powder, and expose it to a violent heat; its oxygen combines with the charcoal forming carbonic acid, while the pure molybdenum remains behind. II. Molybdena, the mineral from which molybdenum is History of generally obtained, was first analyzed by Scheele, whodlscoverT- ascertained it to be composed of sulphur and a white powder which possessed acid properties. Bergman sus- pected that the acid powder discovered by Scheele was a peculiar acid, containing a metal before that time alto- gether unknown. This suspicion was soon after confirmed by Hjelm, who had undertaken the analysis of the powder at the request of Bergman. III. Besides in molybdena (sulphuret of molybdenum) Mineralso'f molybdenum has been discovered in Carinthia, in another ™°£[b^re mineral, called molybdate of lead (a compound of an acid found. of molybdenum and oxide of lead). Both these minerals have been found in the United States. The sulphuret occurs most abundantly in Maine; the molybdate of lead has been found in the Perkiomen lead mine, near Philadelphia, and the Northampton lead mine, Massachusetts.! IV. Molybdenum is a brittle metal of a silvery white Properties. colour, possessing frequently a shade of yellow. V. It is between seven and a half and eight and a half Hjeim times as heavy as water. It is extremely infusible; no heat Buchoiz _______________________________________________________ 8'6U- * From /uow/iSaiva plumbago or black lead; because the mineral from which molybdenum is oht-iined, was formerly considered a species of plumbago. t See Cleaveland's Mineralogy. 40 ACIDIFIABLE COMBUSTIBLES. Book I. to which it has been hitherto exposed has been sufficient to Division '• melt it into a solid button. Forms VI. Molybdenum combines with oxygen in three propor- tlu-ee com-tjons and forms oxide of molybdenum, molybdous acid, pounds with ■ , . .. . . m. , i j u • oxygen; two and molybdic acid. The two last named compounds, having of which acid properties, will be deferred for description under the are acids. • j .• • . head ot acids. Oxide of 1. Oxide of molybdenum may be obtained by expos- nTm^how inS t0 a white hcat' in a crucib^ lhe compound formed obtained, of molybdic acid and ammonia, mixed with some charcoal. The molybdic acid of the compound, by this measure, is partly deoxidized, and reducetl to the state of this oxide. Properties. 2. It has a copper brown colour, and a crystallized ap- pearance. It does not possess the property of forming salts with acids. Moiybde- VII. Molybdenum combines with sulphur, and forms num forms suipnuret Qf molybdenum. It is exactly similar to the asulphuret; r J J native sulphuret called molybdena. how obtain- 1- Sulphuret of molybdenum may be obtained by distil- ed- ling together one part of molybdic acid and five parts of sulphur; the oxygen of the acid is separated, while the metal unites with the sulphur. Properties. 2. This sulphuret has a bluish colour, very much like that of lead. In texture it is composed of scaly particles, which adhere slightly to each other. VIII. Molybdenum forms no other compounds with the substances already described of sufficient importance to be noticed. SECTION VIII. OF TUNGSTEN. Syn. Jt'olframium— Scheelium. Tungsten; I. Tungsten may be obtained by the following process: how obtain- Digest one part of the mineral called tungsten (a compound of an acid, whose base is metallic tungsten, and lime) re- duced to powder, in three parts of nitric acid (aqua fortis) until it acquire a yellow colour. The nitric acid decom- poses part of the mineral, combines with its lime, and sets free a portion of the acid of tungsten. Treat the residue with ammonia, by which means the free tungstic acid is taken up. Put the ammoniacal solution aside. By repeating the treatment, as already described, for a number of times, the mineral may at last be totally decomposed. Now mix TUNGSTEN. ^ j all the ammoniacal solutions of the tungstic acid together, Chap. hi. and add nitric acid as long as any precipitate may appear. The nitric acid thus added combines with the ammonia; and the tungstic acid set free, being insoluble, causes the precipitate above alluded to. Separate the precipitate, and let it be well washed and dried. Then expose it, mixed with charcdai^%te violent heat, in a covered crucible. The charcoal rc^s wP&cid of its oxygen, so that nothing remains but pure tungsten. II. In 1781, Scheele analyzed the mineral called tungs-Discovery, ten, and resolved it into lime, and a peculiar acid which he called tungstic acid. Bergman suspected the base of this acid to be metallic, and his suspicion was afterwards veri- fied by the Messrs. D*Elhuyarts. Th.se chemists found the tungstic acid of Scheele in another mineral called wol- fram;* and they succeeded in decomposing it, by mixing it with charcoal, and exposing it to a very intense heat. III. Tungsten is a brittle metal of a greyish white Properties. colour like that of steel. It possesses considerable bril- liancy. It is one of the hardest metallic bodies. IV. It is one of the heaviest of the metals; being very Spec. grav. nearly seventeen and a half times as heavy as water. It 17'*- requires a very high degree of heat to bring it into a state of fusion; not less than 170° of Wedge wood. When heated in the open air, it becomes oxidized. V. Tungsten combines with oxygen in two proportions, Forms two and forms compounds called oxide of tungsten and tuncrstic compounds drr>, , ' 11- -j • with oxy- . 1 he latter compound having acid properties, its ieni <>ne description will be deferred until the class of acids come to ot wllich is be treated of. an acid- 1. Oxide of tungsten may be formed by passing a current Oxide of of hydrosulphuric acid (sulphuretted hydrogen) through a tungsten; quantity of tungstic acid, heated to redness in a glass tube, tained. The hydrogen of the former abstracts part of the oxygen from the latter, which is thereby reduced to the state of this oxide. 2. Oxide of tungsten has a flea brown colour. When Properties, heated in the open air, it takes fire and is converted into tungstic acid. It is not capable of forming salts with acids. VI. Tungsten combines with sulphur, and forms sulphu Tungsten ret of tungsten. This sulphuret mav be obtained by expos- forms ;i sul ing a mixture of one part of tungstic acid and four parts of p sulphuret of mercury, in a retort, covered with charcoal, to * Wolfram consists of tungstic acid, combined with manganese and iron, F 42 ACIDIFIABLE COMBUSTIBLES book I. a violent heat for half an hour. It is in the form of a greyish Division I. uu^ powder VII. Tungsten forms no alloys with the metals already described. SECTION IX. OF COLUMBIUM. Tantalum of Ekeberg. rniumbi I- Columbium may be obtained by the following pro- »X cess: Fuse together one part of the mineral called tantalite," obtained: five ts Qf salt Qf tartar, and two parts of borax, in a pla- tinum crucible. This fusion is performed in order to make the mineral more soluble in acids. Soften the fused mass with water, and then digest in hydrochloric (muriatic) acid. This acid dissolves off the oxides of iron and of man- ganese, leaving the oxide of columbium untouched. Separate the oxide of columbium from the dissolved oxides, and let it be washed and dried. Then expose it to a violent heat in a charcoal crucible. The charcoal combines with its oxygen, and reduces it to the metallic state. in what mi- II. Columbium has heretofore been found in two mi- nerals found nerals only; the tantalite of Ekeberg, and the columbite and where. of jjatchett. Ekeberg's specimen was found in Sweden; Hatchett's came from America. Historyof HI- This metal was first discovered, in 1801, by discovery. Hatchett, as a constituent in a mineral belonging to the British museum, which had been sent by Mr. Winthrop of Massachusetts to Sir Hans Sloane. Hatchett gave it the name of columbium. Soon after this discovery, Ekeberg detected a new metal in a mineral found in Sweden, to which he gave the name of tantalum. In 1809, Dr. Wollas- ton proved that the columbium of Hatchett, and the tanta- lum of Ekeberg, were the same metal. Properties. IV» Columbium is a dark grey metal, showing the metallic lustre when rubbed against a fine grindstone. It is one of the most infusible metals known, and so hard that its grains are capable of scratching glass. It is also very' brittle, and may be reduced to powder in a mortar. It is extremely insoluble; not being acted upon by hydrochloric 'Tantalite is composed of oxide of columbium combined with oxide of iron and of manganese. SELENIUM. 43 (muriatic) acid, nitric acid, or a mixture of these acids &—>.HI. usually called aqua regia, although digested upon it for several days. V. Columbium is somewhat more than five and a half Spec. grav. times as heavy as water. VI. When heated to redness, it burns feebly without How it any flame; but the combustion ceases the moment it isburns# withdrawn from the fire. VII. Columbium combines with oxygen in one propor- Forms one tion only; and forms a compound called columbic acid. ™™^™y- This compound, having acid properties, its consideration gen; which will be deferred until the class of acids come to be treat- ••an acid' ed of. VIII. Columbium forms no important alloys. SECTION X. OF SELENIUM.* I. This substance was discovered about the beginning of Selenium, the year 1818, by the celebrated Swedish chemist Berzelius, JjfCgVeer^eed in the iron pyrites of the mine of Fahlum in Sweden. Itlius. had been mistaken for the metallic substance called tel- lurium, which will be described hereafter. Berzelius has since found that it constitutes one-fourth of a mineral previ- ously supposed to be an ore of tellurium, in which it is associated with silver and copper. II. Selenium is considered by Berzelius to be a metal, its proper- although having many analogies to sulphur. It has a bril-ties- liant metallic lustre, with a tinge of red. When cooled rapidly it exhibits the vitreous fracture; but, after slow cooling, its fracture is granulated. It is about four and a Spec. grav. half times as heavy as water. It has a certain, but scarcely 4'6- perceptible, transparency. It softens at the heat of boiling water, and in a higher heat, melts. When heated suffi- ciently, it is converted into a yellow vapour like sulphur. It may be sublimed in large vessels, and deposites flowers of the colour of cinnabar. It acquires a certain degree of consistency while cooling, in which state it may be mould- ed in the fingers, or drawn into very fine threads. In a candle it burns with an azure-blue flame, and emits an * From Tixuvn the moon, on account of its analogy to the metal called tellu- rium, which is derived from tellus, the earth 44 INTERMEDIATE COMBUSTIBLES. Book I. odour resembling that of horse-radish, and so powerful Division I. *u„i____cr.:.lL _r „ _ ..-_ _r -^ .1___.___...A ;„ Miflir-iont >. .that one-fiftieth of a grain of it, thus treated, is sufficient to scent a large room. It forms an HI* Selenium combines with oxygen in one proportion, acid with anf] forms an acid. It is therefore an acidifiable combustible. hydRogenr Selenic acid will be described hereafter under the head of indifferent- acids. . It combines also with hydrogen, forming what is called selenur tted hydrogen. This gas has considerable re- semblance to hydrosulphuric acid (sulphuretted hydrogen), and forms compounds analogous to salts, by combining with salifiable bases. It will be described hereafter under the name of hydroselenic acid.* CLASS III. INTERMEDIATE COMBUSTIBLES. Interme- This class contains those combustibles, whose com- bu»tibiesm" Pounds with oxygen are capable of performing the part defined, of acids, or of salifiable bases, under different circumstan- ces, in the formation of neutral salts. and enume- There are only two combustibles belonging to this class; rated. namely, antimony and tellurium. These substances will form the subjects of the tyvo following sections. SECTION I. OF ANTIMONY. Antimony, I. Antimony may be obtained by the following process: toinedb Project by degrees 100 parts of sulphuret of antimony (crude antimony), upon 32 parts of iron filings, previously heated to redness in a crucible. When the whole is in a state of fusion, add by degrees 20 parts of nitrate of potash (nitre); keep it in this state for a few minutes, and then pour it into an iron melting cone, previously heated and greased. The metal, tolerably pure, will be found at the bottom of the cone. How found. II. Pure antimony very seldom occurs native. It occurs most abundantly mineralized with sulphur. In its pure state it has been found at Harwington, in Connecticut. In the form of sulphuret it occurs in several parts of the United States.f * For a further account of selenium, sc Thomson's Anmls, vol. xi. 1818. f See Cleavcland's Mineralogy. ANTIMONY. 45 III. Pure metallic antimony was not known to the Chap. in. ancients; and although they were acquainted with the sul- 3 [ , c -..j ^l ^i_ .wot known phuret of antimony, it does not appear that they supposed pure totho it to be of a metallic nature. Who first obtained it *mancient8- the pure state is not at present known; but the process for procuring it was first described by Basil Valentine, in his writings on antimony, towards the end of the fifteenth century, IV. Antimony is a brittle metal of a greyish white Properties colour, and laminated texture. It possesses a good deal of brilliancy. Its hardness is about equal to that of gold. It communicates to the fingers, when rubbed upon it, a peculiar taste and smell. When exposed to the open air, it undergoes no change except the loss of lustre. V. Antimony is six and nearly three-fourth times as Spec. grav. heavy as an equal bulk of water. It melts when heated to 6'712, redness; if the heat be increased beyond that point, it evaporates. VI. Antimony is capable of combustion. When exposed to a white heat, and then suddenly agitated, it takes on that process. The product of the combustion is an acid called antimonious acid. VII. Antimony combines with oxygen in three propor-Forms tions, and forms compounds which are called oxide ofthree com" antimony, antimonious acid, and antimonic acid. The two wk'hoxy- latter compounds having acid properties, their description Sen;> tw0 of will be deferred until the class of acids come under consi- ^jCsh are deration. The oxide of antimony will be considered in this place. OXIDE OF ANTIMONY. Precipitated Calx of Antimony of the Dublin College. 1. Oxide of antimony may be obtained by diluting with Oxide of water a solution of antimony in hydrochloric (muriatic) antimony; acid. A precipitate appears, which consists of the oxide of tatoed. antimony, combined with a little hydrochloric acid. To separate the acid, wash the precipitate, and boil it for some time in a solution of salt of tartar; wash it again and dry it on a filter. The precipitate is now pure oxide of an- timony. 2. Oxide of antimony is of a dirty white colour, and Properties, destitute of lustre. It is extremely fusible. It has the property of forming salts by combining with acids. 3. Oxide of antimony was formerly used in medicine. At Medical present, however, it is not employed except in combination uses* with sulphuret of antimony, with which it unites in several proportions. These compounds will be described presently. 46 INTERMEDIATE COMBUSTIBLES. Book I. VIII. Antimony combines with chlorine, and forms """on chloride of antimony. Antimony forms a CHLORIDE OF ANTIMONY. Muriate of Antimony of the Ed. College; formerly called Butter of Antimony. 1. This chloride may be obtained by distilling a mixture of two parts of corrosive sublimate (a chloride of mercury) and one part of antimony. It is formed also by the combus- tion of antimony in chlorine gas. When introduced into this gas, the metal catches fire, and the product is the chloride under consideration. 2. Chloride of antimony is a fatty looking substance, of a greyish white colour; very deliquescent and very volatile. When heated moderately it melts. When mixed with water, this liquid is decomposed; its hydrogen combines with the chlorine, forming hydrochloric (muriatic) acid, while its oxygen forms antimonious acid with the antimony. 3. Chloride of antimony is composed of Antimony 45 Chlorine 36 chloride; how ob- tained. Properties. Composi- tion. Medical nses. Iodide of antimony. Phosphu- ret. Sulphuret. Properties, 81 4. Chloride of antimony constitutes one of the most pow- erful caustics known. Being however in a liquid form it is difficult to limit its operation. At present it is never used as an escharotic. IX. Antimony combines with iodine, and forms iodide of antimony. It is very readily obtained by fusing its con- stituents together. It has a dark red colour. When digested in water, it is converted into hydriodic acid and oxide of antimony; that liquid being at the same time decomposed. X. Antimony combines with phosphorus and forms phos- phuret of antimony. It may be prepared by dropping phosphorus into melted antimony. It is a brittle substance, of a white colour and laminated texture. XL Antimony7 combines with sulphur, and forms sul- phuret of antimony. SULPHURET OF ANTIMONY. Crude Antimony. 1. Sulphuret of antimony may be farmed by fusing to- gether its component parts in a crucible. 2. This sulphuret occurs native, and constitutes a very abundant ore of antimony. 3. It has a light leaden grey colour and the metallic lus- tre. Its texture is foliated or radiated. It is much more ANTIMONY. 47 fusible than pure antimony. It is about four and one-third c«ap. ii. times as heavy as water. 4. Sulphuret of antimony combines in several proportions Combines with the oxide of antimony. This combination in the gene- wfiUl .oxide ral way is formed by adding the sulphuret to the oxide nyin seve- while in a state of fusion. It may be formed also by melt- r.al propor- ing in a crucible, the oxide of antimony with different pro- Uons" portions of sulphur: part of the antimony is thereby revived and unites to the sulphur forming a sulphuret; and this sul- phuret combines with the remaining undecomposed oxide. The acids of antimony may be employed, for fusion with sulphur as well as the oxide, in the formation of these com- pounds; as the former are always reduced to the state of the latter during the process. When the sulphuret of antimony is united to the oxide in In one pra- the proportion of one part of the former with eight of the Port,on latter, and the compound fused by a sudden heat, it con- stitutes the preparation called glass of antimony. GLASS OF ANTIMONY. Vitrified Oxide of Antimony with Sulphur of the Ed. College. [1.] Glass of antimony is prepared by the apothecaries, by forms glass exposing sulphuret of antimony in powder, to a gentle heat, of antimo- for a considerable time, in an open vessel. This exposure to ny" heat has the effect of driving off the sulphur from one part of the antimony, which is then converted into oxide. Part of the sulphuret, being in this way oxidized, the whole is melted in a crucible, and kept at an intense heat until it assume the appearance of glass. It is a semitransparent substance of a fine red colour. [2.] Glass of antimony was formerly used in medicine as Medical an emetic; but its operation is so very irregular and uncer- uses- tain, that it has gone out of use. When melted with one- eighth of its weight of yellow wax, it forms the preparation called cerated glass of antimony. The cerated glass is both emetic and cathartic, but more certainly the latter. At pre- sent it is not much employed; and most probably for the same reason that the use of the glass has been discon- tinued. Sulphuret of antimony, combined with oxide of antimony in In another the proportion of one part of the former with four of the ProPortion> latter, constitutes the preparation called crocus of anti- mony. 48 INTERMEDIATE COMBUSTIBLES. Book I. CROCUS OF ANTIMONY. Division I. A)s0 cal,e(] Crocu„ JUetallor urn.—Oxide of Antimony, with Sulphur, by Mtrau of Potash, of the Ed. College. Crocus of [1.] Crocus of antimony may be prepared in the follow- antimony. jng manner. Expose a mixture of equal parts of sulphuret of antimony and nitrate of potash (nitre) each separately pulverized, to a red heat in a covered crucible. A red matter is produced, which must be separated from a whitish crust which is also formed, and afterwards reduced to pow- der and washed, until the water emplo\ ed comes off taste- less. This red matter is the crocus of antimony. Medical C2'] Crocus of antimony agrees in medical properties uses. with the glass; but like the latter preparation, it sometimes acts mildly, at other times most violently. It has accord- ingly gone entirely out of use. Composi- 5. Sulphuret of antimony forms no other important com- w3"htthte Pounc^s l^an ^e two just described. It is composed of Antimony 45 Sulphur 16 61 Medical 6. When reduced to the state of impalpable powder, sul< uses°f the phuret of antimony is sometimes employed in medicine. In general its operation is that of a diaphoretic; but occasion* ally, especially if it meet with acid in the stomach, it is violently emetic and cathartic. It is a powerful remedy in glandular obstructions, and in obstinate cutaneous erup- tions. The dose is from ten to thirty grains. XII. Antimony forms no important alloys with the me- tals already described. Pure anti- XIII. Antimony in the metallic state appears to have very mony not litde or no medical properties. medicinal. SECTION II. OF TELLURIUM. Tellurium: I. Tellurium may be obtained by the following process: how obtain- Dissolve the ore in which tellurium is alloyed with gold and iron, in a mixture of hydrochloric (muriatic) and nitric acids, commonly called aqua regia; and precipitate the gold and iron by adding potash in excess. Separate the precipi- tate, and then add to the solution, hydrochoric (muriatic) acid, just sufficient to saturate the excess of potash: a pre- cipitate appears, which consists of the oxide of tellurium. TELLURIUM. 49 The metal may be obtained from the oxide, by exposing it, Chap. hi. formed into a paste with linseed oil, to heat in a retort. -------~ Brilliant metallic drops make their appearance in the upper part of the retort; these drops consist of tellurium in a state of purity. II. The ores from which tellurium is extracted, have Where heretofore been found only in Transylvania. fouud- III. In 1782 Mtiller was led to believe that the white Account of gold ore (one of the ores of tellurium) contained a new me- d,sc°very. tal, different from all others at that time known. This con- clusion was completely confirmed in 1798 by Klaproth. IV. Tellurium is a bluish vhite metal of a laminated Properties. texture, possessing considerable brilliancy. It is very brittle, and may be easily reduced to powder. Next to mercury and arsenic, it is the most volatile of all the metals. V. Tellurium is somewhat more than six times as heavy Spec. grav. as water. 6l15- VI. When tellurium is exposed to the action of the blow- its combus- pipe, upon burning charcoal, it takes fire and burns with a cribed. lively blue flame, edged with green. VII. Tellurium combines with oxygen in one proportion Forms one only, and forms a compound possessing acid properties. Dr. ^|It'hI>0)"?.d Thomson calls it telluric acid. But as it enters, as a consti- gen, with tuent into neutral s.alts, sometimes as an acid and somc-aci(1.Pro" times as a salifiable base; it would perhaps be better to call r it either telluric acid or oxide of tellurium, according to the It will be part which it may perform in the constitution of any parti- j|escrlbed cular salt. It will be described in this place as a base. 1. Oxide of tellurium may be formed by dissolving the oxide of metal in aqua regia, and diluting the solution with a large quan- how "bud tity of water: a precipitate falls which consists of this oxide, ed. 2. Oxide of tellurium has a white colour. When exposed Properties. to heat, it melts readily into a straw-coloured mass; after fusion if the heat be increased, it is, volatilized. When made into a paste with oil or charcoal powder, it is deoxi- dized with a kind of explosion. 3. It is composed of Compost- Tellurium 32 tioa- Oxygen 8 40 This oxide, in consequence of its acting the part of an acid in some salts, will be ndticed hereafter in the enume- ration of the acids. VIII. Tellurium combines with chlorine and forms chlo- Chloride of ride of tellurium. It is easily formed by introducing the tellurium. metal into chlorine gas; it catches fire spontaneously, and the product of the combustion is this chloride. G 50 BASIFIABLE COMBUSTIBLES Book I. l. Chloride of tellurium is a white and semitransparent Division I. substance. When heated it is converted into vapour. Wa- Properties. ter decomposes it, and precipitates the tellurium in the state of oxide combined with water. Composi- 2. This chloride is composed of Tellurium 32 Chlorine 29'5* tion 61-5 Iodide. IX. Tellurium combines with iodine, when brought in contact with it. The iodide thus obtained, forms a dark purple-red solution in water. X. Tellurium combines with hydrogen and forms a ga- seous compound called telluretted hydrogen. This gas pos- pound with sesses the more essential properties of an acid, and will hydrogen. De described hereafter under the name of hydrotelluric acid. XL Tellurium combines by fusion with sulphur; and the sulphuret formed has a leaden colour. XII. Tellurium forms no important alloys with the me- tals already described. Tellurium forms an acid com- Sulphuret. Basifiable combusti- bles defin- ed. First sub- class of CLASS IV. BASIFIABLE COMBUSTIBLES. Basifiable combustibles have already been defined, to be those combustibles which form the bases of neutral salts, but in no instance acids, by combining with oxygen. These combustibles will be arranged in three sub-classes, as has been already mentioned. SUB-CLASS I. ALKALIFIABLE COMBUSTIBLES. This sub-class includes those basifiable combustibles, which form salifiable bases, possessing alkaline properties, ^eiandefn" ky combining with oxygen. All the salifiable bases formed from these combustibles change vegetable blues to green, with more or less energy. These combustibles are the fol- lowing: namely, enumerat- *• Potassium; 2. Sodium; 3. Lithium; 4. Calcium; 5. Ba- edf rium; 6. Strontium; 7. Magnesium. These substances will form the subjects of the seven fol- lowing sections. SECTION I. OF POTASSIUM. Potassium: I- Potassium may be obtained by the following process: how obtain- Bend a gun barrel in such a form as that its central portion POTASSIUM. 51 will form a curve below the level of its extremities. Fill Chap. hi. this central portion with a quantity of turnings of iron quite clean; and then fix the gun barrel in a furnace surrounded with clay to preserve it from fusion. Place one extremity of the barrel a little higher than the other. Put into the upper extremity a quantity of potash, made as pure and dry as possible; and then adapt to it a curved tube, with its lower extremity plunged into a vessel of mercury. Heat that part of the gun-barrel which contains the iron turnings, to white- ness; and at the moment that this is accomplished, lute a short copper tube to the lower extremity of the gun-barrel, and keep it as cool as possible. Things being thus arranged, apply a sufficient heat to the upper extremity of the gun- barrel, to convert the potash, contained in it, into vapour. The potash thus vaporized passes through the iron turn- ings, and becomes decomposed, and the substance called potassium condenses in the copper tube. As soon as all the potash employed has been converted into vapour, which will be known by there ceasing to be any farther gaseous products, the heat is to be discontinued. The apparatus, after having its ends closed with luting, is then taken from the furnace and cooled as soon as possible. The substance called potassium will be found in the copper tube. To pre- serve it pure it must be kept under naphtha.* II. Potash is composed of the substance under descrip- Explana- tion and oxygen. The explanation of the above process js tion of the therefore this: the potash in vapour, by coming in contact with the iron turnings raised to a white heat, is instantly decomposed; its oxygen combines with the iron, while the potassium liberated from combination passes on and con- denses in the copper tube. III. The important discovery of the compound nature of Discovery. potash was made in 1807, by Sir H. Davy, by the agency of galvanic electricity. The process just described is an out- line of that invented by Gay-Lussac and Thenard. IV. Potassium is a white metal, possessing the metallic Properties. lustre as perfectly as mercury or silver. At the temperature of 50° it is soft and malleable; at 136^° it is perfectly liquid; while at 32° it is hard and brittle. When thrown into water it decomposes that liquid; the hydrogen evolved, carrying with it small particles of the metal, catches fire, and causes the whole of the potassium to burn with a kind of explosion. V. Potassium is lighter than water, being only between Spec. grav. eight and nine-tenths as heavy as that liquid. °865- VI. Potassium combines in two proportions with oxygen, Forms with and forms compounds called potash and peroxide of potas- oxvsen» * Naphtha is a fine thin colourless oil, which comes from Persia. 52 BASIFIABLE COMBUSTIBLES. Book I. sium. The former is formed bv the combustion of potas- Division I. sium in atmospheric air. It will receive a separate conside- ration under the head of alkaline salifiable bases; the latter will be noticed in this place. peroxide of l. Peroxide of potassium is formed by heating potassium how obtain-in Pure oxygen gas. A vivid combustion takes place, and ed. the potassium combines with a larger dose of oxygen, than by combustion in the open air. Discovery. 2. Peroxide of potassium was discovered in 1810, by Gay-Lussac and Thenard. Properties. 3. It is a solid body, of a yellow colour. When thrown into water, it parts with so much oxygen as to convert it into potash. When brought into contact with sulphur, phosphorus, or carbon and the temperature raised, com- bustion takes place; these bodies become acidified, and thus changed, unite to the peroxide now reduced to the state of potash. Under similar circumstances, it converts sulphu- rous acid and protoxide of azote into sulphuric acid and nitric acid respectively. Chloride of VII. Potassium combines with chlorine, and forms chlo- potassium: r'l(\e 0f potassium. CHLORIDE OF POTASSIUM. Usually called Muriate of Potash.—Febrifuge or Digestive Salt of Sylvius. Regenerated Sea Salt of Boerhaave. how obtain- *• Chloride of potassium may be obtained by saturating ed. potash with hydrochloric (muriatic) acid, and exposing the compound formed to a red heat. The chlorine of the acid* combines with the potassium of the potash, while the hydro- gen of the former and oxygen of the latter unite and form water. The exposure to a red heat of the compound has the effect of driving off the water in a state of vapour; so that nothing then remains but chloride of potassium. Another 2. Another method for obtaining this chloride is to heat method, potash in chlorine. The chlorine combines with the potas- sium of the potash, while the oxygen of the latter is disengag- ed. It is also formed when potassium is burnt in chlorine gas; the combustion is attended with a brilliant red flame. Properties. **. Chloride of potassium has a white colour, and a taste resembling that of common salt, but more inclined to bitter. It is not altered by exposure to the atmosphere. Composi- 4. It is composed of tion. Potassium 40 Chlorine 36 76 * The reader is presumed to Le acquainted with the constituents of hydrt- chloric acid; they having been mentioned undsr the head of hydrogen, p. 20- POTASSIUM. 58 5. Chloride of potassium was formerly used in medicine chap, hi. as a sudorific; but at present it has gone entirely out of use. VIII. Potassium combines with iodine and forms iodide Iodide of of potassium. It may be formed by causing the vapour 0f P0,assuun- iodine to come in contact with potassium; the metal takes fire and burns with a violet coloured flame, and this iodide is formed as the product of the combustion. It is in the form of crystals possessing a pearly lustre. It dissolves readily in water. Its exact composition has not been ascer- tained. IX. Potassium combines with hydrogen and forms the Hydruret compound called hydruret of potassium. It may be ob- jJPJ"- tained by heating the metal in hydrogen gas. It is a grey substance destitute of metallic lustre. It is infusible in any heat to which it has as yet been exposed. It does not burn Properties. spontaneously either in common air or oxygen gas. It de- composes water, and is converted into potash, while its hy- drogen, together with that furnished by the water, is evolved. It was discovered by Gay-Lussac and Thenard. X. Potassium exerts no action upon azote; but when Potassium heated in the protoxide of azote (nitrous oxide), it takes ^"™'dw|jlen fire and combines with oxygen in the proportion to form protoxide peroxide of potassium. of azote, XI. Potassium is not known to have any action upon and also carbon; but when heated in carbonic oxide, it catches fire, ™ id5*rbomc and is converted into potash by combining with the oxygen of this gas, while its carbon is deposited. XII. Potassium combines with phosphorus and forms Phosphuret phosphuret of potassium. It is easily prepared by heating °£P°ta8" its constituents in contact with each other. Their combina- tion is attended by the emission of a weak light. It is of a chocolate colour. It burns readily in the open air; and when thrown into water, a kind of detonation is produced in consequence of the rapid evolution of hydroguret of phosphorus (phosphuretted hydrogen). It is composed of Composi- Potassium 40 tion- Phosphorus 12 52 XIII. Potassium combines with sulphur and forms sul-Sulphuret. phuret of potassium. It may be obtained by heating toge- ther its constituents; an intense chemical action occurs, at- tended by all the phenomena of a violent combustion, and the product is this sulphuret. It is of a dark grey colour. Properties. When thrown upon water, it acts upon that liquid with great energy, and hydrosulphuric acid (sulphuretted hydro- gen) is evolved. Although a product of combustion, it is 54 BASIFIABLE COMBUSTIBLES Book I. nevertheless capable of undergoing that process, by which ITIMOn L it is converted into sulphate of potash; its ingredients first uniting with oxygen and afterwards combining with Composi- each other. Sulphuret of potassium is composed of Potassium 40 Sulphur 16 56 XIV. Potassium forms no important alloys with the me- tals already described. SECTION II. OF SODIUM. Sodium: I. Sodium may be obtained from pure soda by a process how obtain- precisely similar to that just described for obtaining potas- sium. It may be obtained also by exposing a mixture of dry common salt and potassium to heat in a close vessel. The salt is decomposed and sodium appears. The explana- tion of the latter process for obtaining sodium is this. Com- mon salt is a compound of chlorine and sodium. When thi|i compound is heated in mixture with potassium, its chlorine. combines with the potassium, forming chloride of potassium; while the sodium liberated from combination appears in its pure state. Discovery. II. Sodium was discovered in 1808 by Sir H. Davy as a constituent in soda, which substance this chemist first de- composed by the agency of galvanic electricity. Properties. III. Sodium is a metal of a white colour, intermediate between that of silver and lead. At the common tempera- ture of the atmosphere, it is soft and malleable. Its fusing point is at the temperature of 194°. Spec. grav. IV. It is very nearly as heavy as water. For'mJsoda ^* Sodium burns in the open air when sufficiently heated, by combus-and combines with oxygen. The product of the combustion air.nlndPen is soda; soda therefore is an oxide of sodium. Soda is also formed when sodium is exposed to the open air; the surface of the metal being converted into soda, by the decomposi- tion of the moisture of the atmosphere. When sodium is thrown into water, this liquid is decomposed, hydrogen is evolved, and it is converted into soda. Soda will receive a separate consideration under the head of alkaline salifiable bases. Besides soda, sodium forms another oxide by com- bining with a larger dose of oxygen than exists in soda; this compound is called peroxide of sodium, and will be noticed in this place. SODIUM. 55 1. Peroxide of sodium may be formed by heating sodium Chap. hi. in oxygen gas; the metal takes fire and burns with great peroxi(le of splendour. The product of the combustion is this peroxide, sodium by It is of a dirty greenish yellow colour. When thrown into ^xyleT water, it gives off so much of its oxygen as to be reduced gas. to the state of soda. It was discovered by Gay-Lussac and Thenard. It is composed of Composi- r c ,. . _ ti6n. Sodium 48 Oxygen 24 72 VI. Sodium combines with chlorine and forms chloride of sodium. CHLORIDE OF SODIUM. Usually called Muriate of Soda.—Common names, Common Salt.—Sea Salt. 1. Chloride of sodium may be obtained by saturating com- Chloride of mon soda (carbonate of soda) with hydrochloric (muriatic) sodium: . , - rv , . ' , - , . v 'howobtain- acid. Its formation in this case takes place in consequence ed. of a double decomposition. The carbonic acid of the carbo- nate is liberated and flies off in the form of gas; the chlo- rine of the hydrochloric acid combines with the sodium of the soda; while the hydrogen of the former uniting with the oxygen of the latter, forms water. It may be obtained however free from water by burning sodium in chlorine gas. The combustion is vivid, and attended by the emission of bright red sparks. The dry chloride also may be obtained by passing a current of chlorine gas over soda previously heated to redness: the chlorine combines with the sodium of the soda, while its oxygen is set free. 3. Chloride of sodium has been known from the earliest Researches ages; but it has only been by very gradual steps that its '"t0 '*s true nature has been ascertained. Glauber knew that hydro- nature* chloric (muriatic) acid could be obtained from it, and Stahl asserted that its base was alkaline. Duhamel ascertained that the base which appeared upon its decomposition was soda, and distinguished it from potash. From these facts, common salt was supposed to be proved to consist of hy- drochloric (muriatic) acid and soda; and it had never been suspected that these alleged constituents did not exist in it, but were in fact the results of new combinations, occurring during its decomposition, before Sir H. Davy made the remarkable discovery, that oxymuriatic acid (chlorine) as yet was an undecompounded substance; which lead the way to the ascertaining of the true nature of the compound un- der consideration. 56 BASIFIABLE COMBUSTIBLES. Book i. 3. The processes just given for obtaining chloride of Division r sodium (common salt) are merely for the purpose of illus- Chloride oftratjnK jts compOS-,tion. The chemist has no occasion to sodium oc- ° , ' ..... i l i »i »• • cursabun- resort to them; as this chloride occurs abundantly native in dantiy na- all parts of the world. It occurs in masses forming the chief part of some mountains. It is found also in solution, in springs, and lakes, but particularly in the ocean. The principal salt mines are found in Poland, Hungary, England and Spain. That near Cracow in Poland has been worked ever since the year 1251. Salt springs are found in almost all parts of the world. Salt lakes are almost peculiar to Russia. Iteextrac- 4. Chloride of sodium (common salt) is obtained from tion from its various sources by different kinds of management. It is and salt ' extracted from salt mines in blocks. If sufficiently pure all springs des-that is necessary is to pound it for U3e; otherwise it must be purified by solution and crystallization. When it occurs in nature in solution, it is extracted by evaporation. If the water contain 15 per cent, of salt, it is generally exposed to artificial heat in a series of large shallow iron pans for eva- poration. It deposites the principal impurities in the fits! pans; and by the time that it has arrived at the last pan is the series, the liquid is a saturated and tolerably pure solu- tion of common salt. The salt precipitates, and is raked out and placed to drain on an inclined plane, at the edge of the last evaporating pan. If a salt spring contain but a small portion of salt, it may cause too great expense in fuel to extract it by the method of artificial heat. In this case, it is brought to the requisite strength, which is considered to be that of containing 30 per cent, of salt, by means of an operation, called graduat- ing. This consists in pumping up the brine to the height of nine or ten yards, and allowing it to fall upon a pile of fag- gots, upon which it is distributed by means of troughs. There is a reservoir below, to receive the brine as it falls. This management has the effect of exposing the brine to the air, minutely divided; whereby evaporation, the sole object of the process, is greatly increased. The brine is pumped up again and again, and allowed to fall over the faggots, until it has acquired the requisite concentration. It is then subjected to evaporation by artificial heat. Sea-water A great deal of common salt is extracted from sea-water erea't8deaf ^v evaporation. This water contains between two and three of common per cent, of common salt. After being first concentrated in salt. large reservoirs, by evaporation in the sun, until it contain about 30 per cent, of salt, it is subjected to artificial evapo- ration. SODIUM. 57 5. Chloride of sodium (common salt) has the well known Cimp.hi. taste, which is distinguished by the epithet salt* It crystal- Chloride of lizes in cubes. It dissolves in about 2*8 parts of cold water, S0^hiu'Ja des" and in about 2*7 parts of boiling water. When somewhat heated, it decrepitates; at a red heat it melts; and at a white heat it evaporates, without undergoing decomposition, in the form of a white smoke. When pure it is not affected by exposure to air; but if contaminated by chloride of magne- sium (muriate of magnesia) it becomes deliquescent. Hence moistness in common salt is an indication of impurity. It is Spec. grav. somewhat more than twice as heavy as water. 2-125. 6. It is composed of Sodium 24 Chlorine 36 60 7. Chloride of sodium (common salt) is of immense uti- Its general lity to mankind. It would appear that man, as well as alluses> phytivorous animals, have an instinctive relish for it as an article of food. It is unquestionably a strong and very grate- ful stimulus to the stomach, exciting that organ and pro- moting the process of digestion. It is one of the most pow- erful antiseptics known. By means of it the flesh of animals may be preserved, fit for food, for any length of time. This property of common salt makes it invaluable to mankind. 8. In medicine, chloride of sodium (common salt) is a Its uses as very useful substance. In active haemorrhagies of the lungs a medicine- and stomach, it is one of the most efficacious and prompt remedies that can be used. In such cases, it may be given dry in the dose of a table spoonful. It is also well suited to some cases of worms in children. In solution it forms the salt bath, which is a very useful remedy in many diseases. It is particularly useful in the scrofulous habit; in chronic eruptions, and in short in all diseases, in which it is expe- dient to excite the vessels on the surface. VII. Sodium does not act upon azote; but when heated Sodium in protoxide of azote (nitrous oxide), it combines with a burns'." maximum of oxygen and is converted into peroxide ofofazote,* sodium. VIII. Sodium has no action on carbon; but when heatecl and in ear- in carbonic oxide gas, it takes fire and is converted intobonic oxide- soda, carbon being deposited. IX. When sodium and phosphorus are brought in con- Phosphuret tact, they combine with the emission of a feeble light. The of S0(,ium- result of the combination is phosphuret of sodium. It has the colour and appearance of lead. When exposed to the open air, or thrown into water, it combines with oxvgen in H 58 BASIFIABLE COMBUSTIBLES. Book i. such a way as to be converted into phosphate of soda. It is ^!°lL composed of Sodium 24 Phosphorus 12 36 Sulphuret X. Sulphuret of sodium may be formed by bringing its of sodium, constituents in contact. The union is attended by the charac- teristic phenomena of combustion; there being much heat and light emitted. It has a deep grey colour. When heated in the open air, it takes fire and is converted into sulphate of soda. It is composed of Sodium 24 Sulphur 16 40 XI. Sodium forms no important alloys with the metals already described. SECTION III. OF LITHIUM. Lithium, I. Lithium is the name proposed to be given to the the metallic peculiar metallic substance, obtained by Sir H. Davy, upon iithia*anew the decomposition of lithia, a new alkaline salifiable base, alkaline discovered about the beginning of the year 1818, by Mr. base.able Arfwedson, a young Swedish chemist, and a pupil of Berzelius. II. Lithium has considerable resemblance to sodium. The only combination into which it is known to enter, ia that with oxygen; whereby it forms lithia.* The alkaline nature of its oxide makes it proper to arrange it among the alkalifiable combustibles. Lithia will be noticed hereafter. SECTION IV. OF CALCIUM. Calcium; I. Calcium may be obtained by exposing mercury to how obtain- negatiVe electricity in contact with pure lime. The lime is decomposed and its base calcium is found, in the state of an amalgam. The calcium may be separated from the mer- cury by distillation in the vapour of naphtha. * See Annals of Philosophy, Vols. xi. and xii. (1818.) CALCIUM 59 II. While Sir H. Davy was pursuing his experiments Chat, hi. upon lime, in order to decompose it, to which he was led its discove- by his previous discovery of the metallic radicals of potash ry- and soda; he received a letter from Berzelius, in which the Swedish chemist communicated the information, that he had, in conjunction with Dr. Pontin, succeeded in decom- posing this substance, and obtaining its radical in a state of combination with mercury. III. Calcium has been but very imperfectly examined. Properties. It is a solid metal of a white colour, resembling that of sil- ver. It possesses considerable weight. IV. When calcium is heated in the open air, it burns Burns in the brilliantly, and the product of the combustion is pure lime. °P^n' Mr Lime will be considered hereafter as an alkaline salifiable iime. base. Calcium has been lately ascertained by Thenard to be capable of combining with more oxygen than exists in Is capable lime. This combination may be effected by adding lime aperoxidf. in excess to superoxidized hydrochloric acid.* The oxygen existing in the acid becomes transferred to the lime and thereby forms a peroxide of calcium.f V. Calcium combines in one proportion with chlorine, Calcium and forms chloride of calcium. foi;ra!with chlorine, CHLORIDE OF CALCIUM. chloride of calcium. Usual chemical name—Muriate of Lime. Old names—Fixed Sal Ammoniac—Calcareous Marine Salt. 1. Chloride of calcium may be obtained by saturating This chio- carbonate of lime (chalk) with hydrochloric (muriatic) acid. ride> how The carbonic acid is evolved; the oxygen of the lime com- ° U,ne ' bines with the hydrogen of the hydrochloric acid, so as to form water; while the calcium of the former and the chlo- rine of the latter unite to form the chloride. It may be ob- tained also by heating lime in chlorine gas. The lime becomes decomposed; its calcium combines with the chlo- rine, while its oxygen is set free. 2. Chloride of calcium has a very bitter and pungent its proper- taste. It is very deliquescent and very soluble. It can-^3- not be easily obtained in crystals. When exposed to a violent heat, a portion of hydrochloric (muriatic) acid is exhaled, which owes its formation to the decomposition of water. The chloride thus altered, has the property of shin- * Thenard has very lately made the extraordinary discovery that hydrochloric. (muriatic) acid, as well as many other acids, is capable of combining with a number of doses of oxygen. The peculiar method, which this chemist practised to effect these combinations, will be mentioned under the heads of the different acids respectively. t Thomson's Annals. (Jan. 18190 60 BASIFIABLE COMBUSTIBLES Book I. Division I. Composi- tion. ing in the dark, as Homberg first observed, and is usually called the phosphorus of Homberg. 3. Chloride of calcium is composed of Calcium 21 Chlorine 36 Medical uses. Iodide of caleium. 57 4. Chloride of calcium in a state of solution, under the name of the water of muriate of lime, has been recom- mended by several physicians in scrofula and other glandu- lar diseases. The average dose for children is thirty drops, and for adults a drachm repeated twice or thrice a day. VI. Calcium combines with iodine, and forms iodide of calcium. It may be obtained by saturating lime with hy- driodic acid, and exposing the compound formed to a strong heat. In the first instance there is formed this iodide and water, by a new binary arrangement of the constituents of the acid* and of the lime. The water formed is then driven off by the strong heat which is directed to be employed. The properties and composition of this iodide have not been made out. SECTION V. OF BARIUM. I. Barium may be obtained by submitting barytes to the same electrical agency by which lime is decomposed. It has been obtained by Dr. Clarke, by exposing barytes to the intense heat produced by the combustion of a stream of oxygen and hydrogen gases, mixed in the requisite propor- tion to form water. II. Barium is a solid metal of the colour of silver. It melts at a temperature below redness; but is not volatilized by a heat capable of producing the fusion of plate glass. It sinks rapidly in water, and is at least four or five times as heavy as an equal bulk of that liquid. III. Barium combines in two proportions with oxygen, and forms barytes and peroxide of barium. Barium, when tesancfper-txposed to the air, absorbs oxygen and is converted into oxide of barytes. When thrown into water, it decomposes this li- quid with great rapidity, and is converted into the same alkaline body; hydrogen being at the same time evolved. Barium; how obtain ed. Its proper- ties. It forms with oxy- gen, bary * The reader is presumed to be acquainted with the constituents of hydriodie acid; they having been mentioned under the head of hydrogeo, p. 20. BARIUM. 61 Barytes will be considered hereafter under the head of al- cha*. hl kaline salifiable bases. The peroxide of barium will be no- ———■ ticed in this place. 1. Peroxide of barium may be formed by heating dryTheperox- barium in oxygen gas. The gas is absorbed very rapidly, jjjj^j^ without the emission of any light. It may be formed also, by adding barytes in excess to superoxidized hydrochloric acid. The oxygen of the acid is transferred to the barytes, which precipitates in the state of peroxide.* 2. This peroxide has a grey colour. When thrown into Properties. water, it separates from so much of its oxygen as to be converted into barytes. When heated in hydrogen, a rapid absorption of the gas takes place, accompanied by the emis- sion of sparks from the peroxide. Its exact composition has not been ascertained. IV. Barium combines in one proportion with chlorine, Barium and forms chloride of barium. chloride. 1. Chloride of barium, usually called muriate of barytes, may be prepared very easily, by saturating carbonate of barytes with hydrochloric (muriatic) acid. The carbonic acid is liberated, and the constituents of the barytes and the acid, unite in such a way as to form the chloride in question and water. It may be formed also by heating ba- rytes in chlorine. The barytes becomes decomposed; its barium combines with the chlorine, while its oxygen is evolved. 2. Chloride of barium has a pungent and disagreeable Its proper- taste. It dissolves in 2^113 of its weight of either hit orties- cold water. It is not altered by exposure to the air. When exposed to a heat, gradually increased, it first decrepitates, then dries, and afterwards melts; but no heat, to which it has hitherto been exposed, is capable of effecting its decom- position. 3. It is composed of Composl- Barium 70 tion- Chlorine 36 106 4. Chloride of barium exerts a very powerful action upon Is an active the animal economy. When taken into the stomach in suf- P0,son- ficient quantities, applied to the skin, or injected into the veins, it produces death very quickly.f Its poisonous qua- lities, however, have not prevented its use in medicine. * Annals of Philosophy, (Jan. 1819.) f See Nancrede's abridgment of Orfila's work on Poisons, p. 167. 62 BASIFIABLE COMBUSTIBLES. Book i. Given in solution, in three times its weight of water, in p"'"on L doses of from five to ten drops, cautiously increased, it is said to have been found useful, as a deobstruent, in remov- ing scrofulous and other tumours. It has also been used in worms, and as an external application in cutaneous erup- tions. But from the present limited knowledge of the powers of this chloride, much cannot be expected from its use. Its extreme activity, however, points to the propriety of ascer- taining the exact operation which it exercises on the human system, when taken in small doses. This once known, it might afterwards, perhaps, be employed in a number of diseases upon sure principles. Iodide of V. Barium is capable of forming an iodide. It may be barium. obtained by passing hydriodic acid over barytes, at the temperature of—4°. The barytes becomes red hot, suffers decomposition, and the resulting compound is iodide of barium. It may be formed also, by saturating barytes with hydriodic acid, and exposing the compound formed to a red heat. In the first instance an iodate of barytes is formed^ this, by the subsequent exposure to heat, is converted into iodide of barium which remains fixed, and water which is driven off in the form of vapour. SECTION VI. OF STRONTIUM. Strontium; I. Strontium was obtained by Sir H. Davy, from how obtain- strontian, by the same means, which were employed in the decomposition of lime and barytes. Its proper- II. It is a solid white metal, considerably heavier than ties. water; and having a close resemblance to barium. Forms with IIL When strontium is exposed to air or thrown into oxygen, water, it combines with oxygen and is converted into stron- and perox- **an' This oxide of strontium will be described hereafter as ide of stron-an alkaline salifiable base. Strontium is capable of forming a peroxide, as Thenard has lately ascertained. It was ob- tained by this chemist by adding strontian in excess to superoxidized hydrochloric acid; the strontian abstracts the excess of oxygen from the acid and falls down as a per- oxide.* Chloride of IV. Strontium combines with chlorine, and forms chloride strontium. 0f strontium, usually called muriate of strontian. • Annals of Philosophy, (Jan. 1819.) MAGNESIUM. 63 1. This chloride may be obtained by saturating car- Chap. Hi. bonate of strontian with hydrochloric (muriatic) acid. It How ob ■ is formed in consequence of a similar decomposition to tained. that which takes place in the formation of the chlorides of calcium and of barium, as already given. 2. It may be formed also by heating strontian in chlorine Another gas: the chlorine combines with the metallic base of the method- strontian, while oxygen is evolved. 3. Chloride of strontium has a peculiar, sharp, penetrating Properties. taste. It dissolves in two-thirds of its weight of cold water; but without limit in boiling water. It is nearly one and a Spec. grav. half times as heavy as water. 1'44" 4. It is composed of Composi- Strontium 44 tion. Chlorine 36 80 V. Strontium combines with iodine, and forms iodide of Iodide of strontium. This iodide may be obtained by saturating 8tl*onUu,l8' strontian with hydriodic acid, and exposing the compound formed to a violent heat in a close vessel. The hydrio- date of strontian is first formed, which, by the subsequent exposure to heat, is converted into the iodide in question. SECTION VII. OF MAGNESIUM. I. Sir H. Davy first obtained this substance from mag- Magnesium nesia, by subjecting it to the same galvanic agency by fijSD°^itt" which barytes and lime had been decomposed. H. Davy! II. Magnesium is a solid white metal, in colour resem- bling silver. III. Magnesium combines in one proportion only with Forms oxygen, and the resulting compound is magnesia. This m»8ne8,a combination takes place whenever magnesium is exposed gen. to the air, or thrown into water. Magnesia will be described hereafter, in a separate section, under the head of alkaline salifiable bases. IV. Magnesium combines in one proportion with chlorine, chloride of and forms chloride of magnesium, usually called muriate o/'magnegium. magnesia. (j4 BASIFIABLE COMBUSTIBLES. Book i. l. This chloride may be formed by heating pure magnesia nix-won I. jn chlorine gas. The chlorine combines with the magnesium, How ob- while the oxygen is evolved. It may be prepared also by tained. dissolving carbonate of magnesia in hydrochloric (muriatic) acid. When prepared in the manner last mentioned, the chloride is combined with water. The water owes its formation to a particular decomposition, of which the reader has had many examples already. Present in 2. Chloride of magnesium combined with water exists •ea water. rea(jy formed in sea water, and in some mineral springs. Properties. 3. Chloride of magnesium has a hot and biting, and extremely bitter taste. It is deliquescent in the air, and cannot be made easily to crystallize. It dissolves in rather more than half its weight of water. When exposed to a strong heat, if water be present, that liquid is decom- posed, and the chloride is changed into hydrochloric. (muriatic) acid and magnesia. Spec. grav. 4. This chloride is somewhat more than one and a half 1-601- times as heavy as water. Composi- 5. It is composed of Magnesium 12 Chlorine 36 48 V. Magnesium is not known to combine with any other substances already described. tion. SUB-CLASS II. Second sub- This sub-class embraces those basifiable combustibles 1fiSbi0fba w*"ck are converted into earthy salifiable bases by com- mnborti- bining with oxygen. They are, 1. Yttrium; 2. Glucinum; bieaenume-3. Aluminum; 4. Zirconium; 5. Thorinum; 6. Silicum. These bodies will form the subjects of the six following sections. SECTION I. OF YTTRIUM. Yttrium: I. Very little can be said under the head of Yttrium. Sir how obtam- h. Davy succeeded in the decomposition of the earthy sa- lifiable base yttria, by passing potassium over it, when heated to redness: the potassium was converted into potash, and a number of metallic particles were developed. From the result of this experiment, there can be no doubt that ALUMINUM. 65 yttria was decomposed; but its base was obtained in quan- Cbap. HI tities too small to admit of accurate examination. II. At present the only substance known to be capable Combined of combining with yttrium is oxygen; and the result of the gjn\S combination is yttria. Yctria will be described hereafter yttria. under the head of earthy salifiable bases. SECTION II. OF GLUCINUM. I. Glucinum was obtained from the earthy salifiable Glucinum: base glucina, by heating it in contact with potassium. The howobtaiu- potassium became converted into potash, and a number of dark coloured metallic particles were developed. These particles were considered to consist of a peculiar metal, which was accordingly called glucinum. II. Glucinum, when thrown into water, decomposes that Forms glu- liquid, combines with oxygen, and is converted into glucina. JJJ^jJj,^ Synthesis, therefore, as well as analysis, goes clearly to with oxy- show that glucina is an oxide of glucinum. Glucina will be Sen> described hereafter under the head of earthy salifiable bases. SECTION III. OF ALUMINUM. I. Sir H. Davy was led, from analogy, to suspect that Aluminum: alumina (in an impure state called clay) like the other howobtaiu- earthy salifiable bases, was a compound of a metallic body and oxygen; and he verified this suspicion by passing potassium over alumina heated to whiteness. The potas- sium became converted into potash, and a peculiar metallic substance was developed, which, when thrown into water, combined with oxygen, and produced alumina. The fair conclusion to be drawn from these facts is, that alumina is composed of the peculiar metal thus obtained and oxygen. It is this peculiar substance which is called aluminum. II. Aluminum has not been obtained in sufficient quanti-Its proper- ties to enable the chemist to give it an accurate examination. *"*> not as" The only combination into which it is known to enter is Combined that with oxygen, which results in the formation of alumina, with °*y- as already stated. Alumina will be described hereafter, Ifum^™ under the head of earthy salifiable bases. I (J6 BASIFIABLE COMBUSTIBLES. dS/i. SECTION IV. OF ZIRCONIUM. Zirconium: I. Zirconium was exposed by Sir H. Davy to the same how obtain-agents of decomposition, by which the other earthy salifia- ble bases were decomposed; and it gave similar indications of being a compound of a peculiar metallic body and oxy- gen. Zirconium is the name applied to this peculiar sub- stance. formszir- II. It has not been possible heretofore to make out the coma m properties of this metal. The only substance with which it is combina- f r ... • i 1 • t_ •,. r tion with known to combine is oxygen, with which it torms zirconia. oxygen. Zirconia will be described hereafter under the head of earthy salifiable bases. SECTION V. OF THORINUM. Thorinum, I. Berzelius has discovered, in a mineral found in eu^dwfT"Sweden, an incombustible body, which has all the pro- of the perties of an earthy salifiable base. He has given to it the earthy sah-name Qf thorina. There can be very little doubt that this nflOlP D33C thorina. body is similarly constituted to those usually called earths, and consequently that it is a metallic oxide. Depending upon the evidence of this close analogy, Berzelius has assigned to it a metallic base, which he calls thorinum. Thorinum, therefore, is a hypothetical substance; and is introduced here for the sake of perspicuity, and to avoid the anomaly in arrangement of placing thorina in the same class with azote; which position it would have to assume upon the supposition that it was not a compound. II. Thorina will be described hereafter, under the head of earthy salifiable bases. SECTION VI. OF SILICUM.* Silicum: I« Silicum was first obtained, through the agency of how ed. how obtain-galvanic electricity, from silica (pure flint) by professor * Dr. Thomson places silicum among the acidifiable combustibles; because he believes that sufficient reason has been given for supposing that silica (oxide ot silicum) performs the part of an acid. In this particular I have not followed Dr. Thomson; not being satisfied that its close analogy to acids has been well made out. There are indeed some circumstances with regard to silica, in which it differs particularly from all the other earthy salifiable bases; but these do not call for the measure of associating it with acids, where it cannot stand without vio- lating the obvious and natural analogies of chemical bodies. IRON. 67 Berzelius of Sweden. It was, however, in a state of alloy Chap.ih. with iron. It was afterwards obtained in a separate state, by Sir H. Davy, by passing potassium in excess overheat- ed silica, contained in a platinum tube. But the quantities in which it was obtained were too small to enable this chemist to make out many of its properties. II. Silicum, obtained by Sir H. Davy's method, appears Forms siii- in the form of a dark coloured powder. It seems capable of "a» um*ed bearing a very high temperature without alteration. When thrown into water, it decomposes that liquid, combines with oxygen, and is converted into silica. Silica will be described hereafter, under the head of earthy salifiable bases. III. Silicum, combined with fluorine, is supposed to con- Supposed stitute the peculiar acid called fluosilicic acid. It is form- to form an ed by the distillation of fluor spar with sulphuric acid in fluorine. glass vessels. It will be described hereafter under the al- tered name of silicofluoric acid. SUB-CLASS III. This sub-class of basifiable combustibles comprises those Basifiabit which form, by combining with oxygen, salifiable bases, ^ mbf8,J_" which have neither alkaline nor earthy properties. They third sub- are the following: class. e"u- 1. Iron; 2. Nickel; 3. Cobalt; 4. Manganese; 5. Cerium; merate,r- 6. Uranium; 7. Zinc; 8. Lead; 9. Tin; 10. Copper; 11. Bismuth; 12. Mercury; 13. Silver; 14. Gold; 15. Plati- num; 16. Palladium; 17. Rhodium; 18. Iridium; 19. Os- mium; 20. Titanium. All these combustibles are metals. They will be described in the order in which they have been named in the follow- ing sections. SECTION I. OF IRON. I. Iron may be obtained pure by the following process: Processfoi Treat the mineral called pyrites, which is a sulphuret of iron, .obtainins repeatedly with boiling nitric acid. By this measure the ir°n ptlVe' sulphur becomes acidified and the iron oxidized; so that the sulphuret is changed into a sulphate of iron. Decompose this sulphate by means of hydrochloric (muriatic) acid: this acid separates the sulphuric acid, and combines with the oxide of iron, leaving the impurities untouched. To the solution as it now stands, add chloride of barium (muriate of barytes): water is immediately decomposed; the barium 58 BASIFIABLE COMBUSTIBLES. Book I. is converted into barytes, which, combining with the sul- Division I. phuric juid, forms the insoluble compound called sulphate of barytes; while the chlorine combines with hydrogen, and is changed into hydrochloric (muriatic) acid. After separating the insoluble sulphate of barytes by the filter, nothing re- mains but a solution of pure oxide of iron in hydrochloric (muriatic) acid. To this solution add a solution of carbo- nate of soda (common soda): a double decomposition in- stantly takes place; the carbonic acid and oxide of iron com- bine and form the insoluble compound called carbonate of iron; while the hydrochloric acid and soda unite so as to form chloride of sodium (common salt) and water. Separate the carbonate of iron by the filter, and after being washed and dried, expose it to the action of a strong red heat: the car- bonic acid is driven off, the oxide is reduced, and a button of pure iron is obtained. Iron, ex- II. When iron is separated from its ores by the manu- tracted facturer, the process is very different from that just given; ores, ob- and the result is the production of the metal in a state very tained in far from beine pure. It is called cast iron, and owes its pe- the form of ,. • . »u c u east iron, cuhar properties to the presence ot carbon. Process for !• The ore from which cast iron is obtained is generally obtaining a mixture of oxide of iron and clay. It is reduced to small east iron. pjeees^ mjxed with charcoal and limestone (carbonate of lime) and exposed to a violent heat in a furnace, whereby the whole becomes melted. After remaining in fusion for a sufficient time, a hole is opened in the lower part of the furnace and the iron runs out. Process 2. In the above process the use of the limestone and explained, charcoal may be thus explained. At the high temperature to which the ore is raised, the oxygen which it contains, combines with the charcoal and flies off in the form of car- bonic acid. On the other hand the lime of the limestone combines with the clay and forms a kind of liquid glass. This fused compound being lighter than the iron, swims on the surface. In this way both the substances, with which the metal is combined in the ore, are separated. The open- ing made in the lower part of the furnace allows the iron to run out unmixed with the supernatant impurities. 3. If the iron ore contain sulphur and arsenic, these substances are to be driven off by exposure to a sufficient heat. This process is called roasting. Cast iron is 4. Cast iron, according to its colour, is distinguished into flWh' e several kinds. White cast iron is very hard and brittle; not cast iron; susceptible of being filed, bored or bent, and very liable to 2. Grey break when suddenly cooled. Grey or mottled cast iron has on"or a granular texture, and is not nearly so hard or brittle as WON. 69 the preceding kind. It may be cut, bored, or turned on a Chap. hi. lathe. Artillery are manufactured from this kind of cast--------- iron. Black cast iron is the most variable in its texture of 3. Black all the species of cast iron. It is more fusible and less co- cast iron- hesive than the other varieties. Cast iron melts when heated to about 130° of Wedgewood's pyrometer.* Upon fusion it contracts considerably, contrary to the usual effects of heat. It is between seven and seven and a half times as heavy as water. 5. Besides carbon, cast iron contains oxide and phosphu- Different ret of iron, and silica. It has been found by experiment that ££ l0£a White cast iron "] S „ f ryth of its weight of carbon, different Grey cast iron tlji*- ed pure. 76 BASIFIABLE COMBUSTIBLES. Book I. ists alloyed by several others, in sulphuric acid, assisting PivUion l the solution by the addition of some nitric acid. Concen- trate the solution, and let it stand for several hours. Green crystals of sulphate of nickel will be observed to form. This treatment must be repeated until a sufficient number ot these crystals are obtained. Dissolve them in water, and drop into their solution, a solution of potash or of soda. This addition precipitates the nickel in the state of oxide. The oxide may be deoxidized by being made into a paste with oil, and exposed in a charcoal crucible to a very vio- lent heat. The oxygen flies off in combination with the char- coal, so that nothing remains but the pure metal. Its ores, II. The ores of nickel are found, for the most part, in found* Germany. That which occurs most abundantly is called kupfern'tckel, or false copper, from its resemblance to the ores of copper. It is composed principally of nickel and arsenic. Its discove- HI. Nickel was discovered in 1751 by Cronstedt, by *y- whom it was called by its present name. Properties IV. Nickel has a fine white colour, resembling silver. Its of nickel, hardness is considerable, but less than that of iron. It is malleable when either hot or cold. Like steel it may be converted into a magnet. It is not altered by exposure to air or immersion in water. Its fusing point is at least as high as 160° of Wedge wood. Spec. grav. V. It is somewhat less -than eight and a half times as 8-402. heavy as water. Its weight is considerably increased by hammering. Nickel VI. Nickel combines in two proportions with oxygen, forms ancj forms protoxide and peroxide of nickel. l. a protox- 1» Protoxide of nickel may be obtained by dissolving nick- ide, and el in nitric acid, and adding potash to the solution thus formed. The nickel is thrown down in the state of this oxide. 2. Protoxide of nickel has a blackish ash-grey colour, but no taste. Its solutions in acids have a grass green co- lour. It forms a pale blue coloured solution with ammonia. 3. It is composed of Nickel 27 Oxygen 8 ide 35 2.aperox- 1. Peroxide of nickel may be obtained by the following process: Pass a current of chlorine gas through water, in which protoxide of nickel is suspended: water becomes de- composed; its hydrogen combines with the chlorine, forming hydrochloric (muriatic) acid, while its oxvgen unites to a portion of the oxide, so as to change it from protoxide to COBALT. 77 peroxide. The peroxide thus formed, being insoluble, is Chap. III. easily separated. The unaltered portion of the oxide dis- solves in the hydrochloric acid. 2. Peroxide of nickel has a black colour. It dissolves in ammonia with effervescence, yielding up at the same time part of its oxygen, which combines with the hydrogen of the ammonia, the azote of the latter being evolved. Its so- lution in acids is attended with effervescence also; owing to the evolution of oxygen, during its conversion into pro- toxide. 3. It is composed of Nickel 54 Oxygen 24 78.—Thus this oxide contains one and a half times as much oxygen as the pro- toxide; or, which is the same thing, twice as much nickel, united to three times the quantity of oxygen. VII. Nickel combines in one proportion with chlorine, Chloride of and forms chloride of nickel. This chloride cannot be form- n,c e ' ed by combustion; but it may be obtained by subliming dry hydrochlorate (muriate) of nickel. Its properties and com- position have not been ascertained. VIII. Phosphuret of nickel may be formed by dropping Phosphu- phosphorus upon metallic nickel, while at a red heat. It is ret- a very britde and moderately hard substance of a tin white colour. It possesses the metallic lustre. IX. Sulphuret of nickel may be formed by fusing toge- Sulphuret ther its constituents. It has a yellowish white colour. SECTION III. OF COBALT. I. Cobalt may be obtained by the following process: Cobalt;how Treat, by the assistance of heat, one part in powder ofobtaIne<1 the ore of cobalt, in which the metal exists minera- lized by arsenic, iron and sulphur, with three parts of aqua regia, as long as any portion of it is dissolved. The aqua regia dissolves all the ore except the sulphur. Filter the liquid obtained, in order to separate the insoluble part, and add to it, a solution of carbonate of potash, as long as it causes any precipitate. This precipitate consists of cobalt combined with iron and arsenic. Separate it by the filter, dissolve it in nitric acid and add ammonia. This step in 78 BASIFIABLE COMBUSTIBLES. Where found. Its discove Properties of cobalt. Spec, grav 8-53. Cobalt forms two oxides. 1. Protox- ide. Its proper- ties. the process throws down the metals in combination with am- monia. The metals, by being in this state of combination, are rendered soluble in acetic acid (pure vinegar). Accord- ingly dissolve the precipitate last formed in acetic acid, and evaporate the solution until it let fall a red powder this powder will prove to be oxide of iron. After it is se- parated, the remaining solution consists of acetate of cobalt contaminated with arsenic. In order to separate the arsenic add liquid ammonia. The ammonia combines with th« co- balt and remains in solution, while the arsenic falls* The arsenic being separated by the filter, nothing remains but an ammoniacal solution of cobalt. Evaporate this solution to dryness, to drive off the ammonia, and expose the dry mass, being oxide of cobalt, mixed with three parts of black flux and one part of borax, to a violent heat in a crucible. The oxygen becomes separated by the flux, and there is obtained a metallic button of cobalt. II. Cobalt is found principally in Germany, Sweden, Norway and Hungary, mineralized usually by arsenic, iron and sulphur. It has occasionally been found combined with sulphuric and arsenic acids. III. Cobalt was discovered in 1733 by the Swedish che- mist Brandt, by whom it was called by its present name. IV. Cobalt is of a grey colour with a shade of red. It is rather soft, and has very little metallic brilliancy. It has scarcely any taste or smell. It undergoes no change from exposure to air or immersion in water. Its fusing point is at the temperature of 130° of Wedge wood. V. It is a little more than eight and a half times as heavy as water. VI. Cobalt unites in two proportions with oxygen, and forms protoxide and peroxide of cobalt. 1. Protoxide of cobalt may be obtained by dissolving co- balt in nitric acid, and precipitating the solution by means of potash. The precipitate must be washed and dried, and exposed to a cherry red heat, to drive off the oxygen, which it will have absorbed during the process of drying; it is then pure protoxide of cobalt. 2. This oxide has a fine blue colour. It dissolves in acids without effervescence. Its solution in hydrochloric (mu- riatic) acid, when eoncentrated is blue, but when diluted, red. In sulphuric or nitric solutions, it is always red. It enters into the composition of the salts of oxidized cobalt. 3. Protoxide of cobalt is composed of Cobalt 29 Oxygen 8 37 MANGANESE. 79 1. Peroxide of cobalt may be formed by heating the pro- Chip. in. toxide in the open air. The protoxide absorbs oxygen and 2 Perox. becomes converted into peroxide. ide. 2. This oxide has a black colour. It gives out part of its its proper- oxygen with effervescence, when dissolved in hydrochloricties- (muriatic) acid; chlorine being at the same time evolved. It does not enter into the composition of salts. 3. Peroxide of cobalt is composed of Cobalt 58 Oxygen 21* 79.—When this oxide is compared with the protoxide as to composition, it will be perceived that it contains twice as much cobalt, combined with somewhat less than three times as much oxygen. So that the numbers of the two oxides do not admit of any exact comparison. VII. Chloride of cobalt may be formed by burning chloride of cobalt in chlorine gas. It has not been examined with ac- cobalt. curacy. VIII. Phosphuret of cobalt may be formed by heating Phosphu- the metal red hot, and dropping into it small pieces ofret- phosphorus. It is a white and brittle substance, which soon tarnishes in the air. It contains about T*Tth of its weight of phosphorus. IX. Sulphuret of cobalt may be formed by melting the Sulphuret. metal with sulphuret of potash: the sulphur combines with the metal, and the potash is separated. It has a yellowish white colour. Its composition is not accurately known. SECTION IV. OF MANGANESE. I. Manganese may be obtained by the following pro- Manganese cess: Make up the black oxide of manganese, finely pow- Jj°w obtain" dered, into a ball with pitch. Put it into a crucible lined P"re with charcoal, and filled with charcoal powder. Close the crucible with a cover, which must be well luted on. The whole must then be exposed, for an hour, to the strongest heat that can be raised. A small button of the metal will be found in the bottom of the crucible. II. Manganese, almost always in the state of oxide, is Where found abundantly distributed in different parts of the world; found- particularly in France, Spain, Germany and England. 80 BASIFIABLE COMBUSTIBLES. Book I. Division I. Discovery. Properties of manga- nese. Spec. grav. 8 013. Manganese forms three oxides. 1. Protox- ide. III. About the year 1770, several chemists suspected that the mineral called manganese was a metallic oxide; and Kaim published a set of experiments to prove that a metal might be obtained from it. Numerous attempts were made to reduce it to the metallic state, which were unsuccessful, until Gahn invented the process which has just been des- cribed. IV. Manganese has a greyish white colour, resembling that of cast iron, and considerable brilliancy. It has neither taste or smell. It is softer than cast iron and yields to the file. It is very brittle, and its fracture is uneven and fine grained. In the air, it loses its lustre; becoming succes- sively grey, violet, brown and at last black. When thrown into water it decomposes that liquid with considerable ra- pidity; hydrogen being at the same time evolved. Its fusing point is at the temperature of 160° of Wedgewood. V. It is very little more than eight times as heavy as water. VI. Manganese combines in three proportions with oxy- gen, and forms protoxide, deutoxide and peroxide of man- ganese. 1. Protoxide of manganese may be obtained by dissolv- ing the mineral called manganese in an acid, and precipi- tating the solution by potash. The precipitate which appears consists of this oxide. It is an olive-green powder, which becomes black upon exposure to air, in consequence of the absorption of oxygen. It is this oxide generally, which en- ters into the composition of the salts of oxidized man- ganese. 2. It is composed of Manganese 28 Oxygen 8 •&. Deutox- ide. 36 1. Deutoxide of manganese may be formed by exposing nitrate of manganese to heat; or by burning the protoxide in the open air. It has a black colour. 2. It is composed of Manganese 56 Oxygen 24 80.—So it appears that this oxide contains three times as much oxygen, united to twice as much manganese, as the protoxide.* * Thomson's Annals, xi. 228. (Mar. 1818.) MANGANESE. 3 J 1. Peroxide of manganese (black oxide of manganese) Chap. hi. need never be formed by the chemist. It occurs abuudantly 3 perox. native, particularly in the county of Devonshire, England, ide. When pure it has a radiated texture, and a dark steel-grey colour. Its lustre is considerable. It is brittle, very soft, and soils the fingers. It is about four and three-fourths as heavy as water. When heated to redness, it is converted into a red powder, which, by treatment with acids, imme- diately separates into protoxide and deutoxide.* Hence it is probable ihat this powder is a mixture of these oxides. 2. Peroxide of manganese is composed of Manganese 28 Oxygen 16 44—so that it contains twice as much oxygen as the protoxide.f VII. Manganese combines in one proportion with chlo- Manganese forms a chloride. rine, and forms chloride of manganese. 1. This chloride was first obtained by Dr. John Davy, by dissolving peroxide of manganese in hydrochloric (mu- riatic) acid, evaporating the solution to dryness, and ex- posing the dry mass, thus obtained, to a red heat in a glass tube with a narrow orifice. 2. Chloride of manganese has a delicate pink colour, and Its propef- a lamellar texture. Whene xposed to the open air, it deli-ties- quesces, and is converted into hydrochlorate (muriate) of manganese. 3. It is composed, in whole numbers, of Manganese 28 Chlorine 33* 61 VIII. Phosphuret of manganese may be formed by Phosphuret dropping phosphorus upon red hot manganese. It is aot m&nSAm white brittle substance of a granular texture. It is not altered by exposure to air. It fuses much more readily than manganese. IX. Sulphuret of manganese may be formed by heating Sulphuret. sulphur and manganese together. Its properties and com- position have not been accurately made out. ' Thomson's Annals, xi. 228. (March, 1818.)—f Ibid. 32 UASIPIABLE C«»IBUSTIBLK> Book I. Division I. SECTION V. OF CFKIUM Cerium; how obtain ed pure. I. Crrjum may be obtained by the following process:— Digest the mineral called* cerite (u compound of oxide of cerium, silica, and oxide of iron) in fine powder in nitric acid, until every thing soluble is taken up. The nitric acid dissolves the oxides, and leaves, the silica untouched, which appears in the form of, an insoluble residue. Decant the clear solution from this residue, and add to it oxalic acid, as long as any precipitate appears. This acid falls in combina- tion with the oxide of cerium, while the oxide of iron still remains in solution. Separate this precipitate, and, after being washed and dried, expose it. to a red heat* The oxalic acid is decomposed and driven off, and a red powder ia obtained, which is cerium in the state of oxide. The reduc- tion of the oxide to the metallic state, by means of carbo- naceous substances, is attended with great difficulty, and is accomplished, under the most favourable circumstances, ill an imperfect manner only. Sir H. Davy, however, suc- ceeded in obtaining the metal pure, by heating the oxide in contact with potassium. The potassium becomes converted into potash, and the pure metal is developed. II. Cerium has been found hitherto principally in Sweden. It occurs combined with silica andiron, in the mineral called cerite; and also with hydrofluoric (fluoric) acid, yttria, and thorina, in several other minerals. III. Before the discovery of the metallic nature of the earthy salifiable bases, it remained for some time doubtful whether the powder obtained from cerite was an earth or a metallic oxide. Klaproth supposed it was an earth; and Vauquelin was in doubt which of the two to consider it Hisinger and Berzelius obtained the same peculiar pow- der from the mineral, and considered it a metallic oxide: but these chemists were unable to reduce it.to the metallic state. Vauquelin re-examined the powder, with the view.W reduce it, if possible. These attempts, although unsuccessful, were sufficient to demonstrate its metallic nature. It was ultimately reduced by Sir H. Davy in the manner already mentioned. IV. Cerium has been but very imperfectly examined. According to Sir H. Davy, it is a deep-grey metallic powder. Forms two V*. Cerium forms, with oxygen, a protoxide and a oxides. peroxide. The former is white; the latter reddish-brown. Where found. Account of its discove- ry. Properties of cerium. URANIUM. 33 No accurate analysis has been made of them. They both Cbaf. hi. enter mto the composition of the salts of oxidized cerium* "^—~r~~~ SECTION VI. OF URANIUM. I. UraniOm may be obtained frompechblende (a mineral Uranium; in which the metal exists in the state of oxide, mixed with Jj"^*""- sulphuret of lead, oxide of iron, and silica) by the following process: Roast the mineral for some time, in order to drive off the sulphur; and then digest it in nitric acid, until every thing soluble is taken up. The acid dissolves the metals, and leaves the silica. Decant the clear solution, and add to it carbonate of potash as long as any precipitate appears: this precipitate consists of oxide of uranium, united to carbonic acid. Separate it, and, after being washed and dried, expose it, made up into a paste with oil, in a crdcible lined with charcoal, to a violent heat. The carbonic acid is driven off, and the oxygen of the oxide separated; so that nothing remains but pure uranium. II. Uranium is found in the state of oxide, mixed with Where small quantities of iron, lead, and copper, in ores which fo?nd- occur in Germany, Norway j France, and England. III. It was discovered in 1789* by Klaproth, by whom it was called by its present name. IV. Uranium is a metal, having an iron-grey colour, and Its proper- considerable lustre. It is soft enough to yield to the file. ties- V. It is somewhat more than eight times as heavy as Spec. grav. water. 810°- VI. Uranium forms, with oxygen, a protoxide and per- Forms two oxide; both of which have the property of neutralizing oxides. acids. I. Protoxide of uranium may be formed by heating the i. Protox- metal to redness in an open vessel. It glows like a liveide- coal, absorbs oxygen, and is converted into a powder, which consists of this oxide. Its colour is greyish black. 2. It is eon posed of Uranium 125 Oxygen 8 133 1. Peroxide of uranium may be obtained by dissolving 2. Peroxide. uranium in nitric acid, and precipitating the solution by potash. The precipitate which appears is the oxide in question. It has a yellow colour. Ghievreul has noticed that 84 BASIFIABLE COMBUSTIBLES. Book I. it is capable of changing the blue colour of litmus to red. Divi3ion L He has, therefore, attributed to it acid properties.* If it should prove to be capable of neutralizing salifiable bases, it would be more properly called uranic acid. 2. It is composed of Uranium 250 Ox\ gen 24 274—or, which amounts to the same thing, it contains three times as much oxygen, united with twice as much uranium, as the protoxide. SECTION VII. OF ZINC. Zinc; how I. Zinc may be obtained by exposing the mineral called obtained, blende (sulphuret of zinc), after being roasted and reduced to a fine powder, to a strong heat, mixed with charcoal, in large clay pots closed from the air. By this treatment the blende is first changed from a sulphuret into an oxide, which is afterwards deoxidized by the charcoal. Occurs ge- II. Zinc occurs abundantly native, mineralized most m rally as a generally by sulphur, constituting the ore called blende. It su p uret. occurs^ in t^e form 0f an oxide, in the iron mines of Sussex county, New Jersey. Properties III. Zinc has a brilliant white colour, with a shade of of zinc. blue. It is rather soft, and in texture consists of a num- ber of thin plates adhering together. It has a peculiar taste and perceptible smell. Its malleability is at a mean; being not so malleable as copper, or so brittle as antimony or arsenic. It may be pressed out into thin plates, by rollers, without breaking. When heated to 212°, it becomes very malleable. It is also ductile in a certain degree. When heated to the temperature of 680*, it melts; and if it be exposed to a greater heat in close vessels, it evaporates and mav be distilled overt In air it suffers only a slight tarnish; but, under water, it absorbs oxygen at the expense of this liquid, and becomes black. Spec. grav. IV. It is some what less than seven times as heavy as water. 6 86i y^ Zmc combines with oxygen in one proportion only, bu't'oneox-and forms OX',(le °f Z'mC' ide; 1. Oxide of zinc, formerly called fiowers of zinc, may be formed by heating zinc to redness in an open vessel. The * Annals of Philosophy, xii. 144. (August 1818.) ZINC. 85 metal takes fire, and burns with a brilliant white flame, chap. hi. emitting white flakes in great abundance. These flakes con- stitute the oxide in question.^ 2. It is a tasteless and insoluble white powder. It com- bines easily with acids, and forms salts. 3. It is composed of Zinc 33 Oxygen 8 41 4. Oxide of zinc is used in medicine. It acts as a tonic, which is and is supposed to be suited to the cure of spasmodic "se.d in me- diseases. It has been particularly praised in epilepsy. Its dose is from one to eight grains. When made into the form of an ointment, it has been found useful as an exsic- cant in excoriations. 5. When lead ores, which are accompanied by zinc, are impUro ox. refined, there condenses, in the chimnies of the furnaces em- We of sine, ployed, a substance, which is oxide of zinc in an impure descrioed. state. It was formerly called tutty. It is a brown substance full of protuberances on the outside, but smooth and yel- lowish within. It is employed in medicine, in the form of an ointment, which is considered very efficacious as an ap- plication to inflamed eye-lids. It has hardly been applied to any other use. VI. Zinc combines with chlorine, and forms chloride of Zinc forms zinc. a chloride. 1. This chloride may be obtained by dissolving zinc in hydrochloric (muriatic) acid, evaporating the solution to dryness, and exposing the dry mass to a red heat in a glass vessel with a narrow orifice. By the exposure to the red heat, the hydrochlorate of zinc, which is first formed, is decomposed into chloride of zinc which remains fixed, and water which is driven off in the state of vapour. It may be obtained also by direct combination, by introducing zinc into chlorine gas: the metal catches fire, undergoes combustion, and is converted into this chloride. 2. Chloride of zinc is fusible, but does not sublime, at a Its proper- red heat. When exposed to the air, it deliquesces, and is ties- converted into hydrochlorate (muriate) of zinc. 3. It is composed of Zinc 33 Chlorine 33* 66 VII. Zinc combines with iodine by means of heat. The iodide of iodide formed has a white colour, and is deliquescent in zinc- 85 BASIFIABLE COMBUSTIBLES. Boo* I. the air. When dissolved in water, it decomposes this Division I. ijgmjd. and is converted into hydriodate of zinc It is composed of Zinc 33 Iodine 125 158 Phosphu- VIII. Phosphuret of zinc may be formed by dropping «*• small pieces of phosphorus into melted zinc. It has a white colour and the metallic lustre. It possesses some degree of malleability. Sulphuret. IX. Sulphuret of zinc, as has been mentioned* occurs native in abundance under the name of blende. It cannot easily be formed artificially. It is a tasteless, insoluble substance of a brown colour. It is about four times as heavy as water. Cadmium, Since this volume was prepared for the press, I find, by a new me- the scientific journals, that Stromeyer has discovered a wed'Ty new metal, to which he has given the name of Cadmium* Stromeyer. The discovery was made in the autumn of 1817. This metal owed its discovery to the following circum* stances. Stromeyer, while making a general inspection of the apothecaries' shops, found, that, in several of them, a carbonate of zinc was sold under the name of the oxide. Upon inquiring the reason of this, at the manufactory where the preparation of zinc had been made; the explana- tion given was, that the carbonate, when exposed to heal for conversion into oxide, always assumed a yellow colour, seeming to indicate the presence of iron or lead, although neither of these metals could be detected in it. The result of the examination of this suspected oxide, by Stromeyer, was the discovery of cadmium, to which it owed its pecu- liar colour. Since making this discovery, Stromeyer has found the same metal in tutty, and several other oxides of zinc, but always in small amount, varying from 1 per cent. to -^ of 1 per cent. He has, however, more lately discover- ed it in a preparation of zinc from Silesia, which had been supposed to contain arsenic. In this last, the new metal exists to the amount of three per cent. Its proper- Cadmium has a light white colour, inclining a little to ties. grey. It possesses considerable brilliancy, and admits of a fine polish. It has a compact texture and hackly fracture. Spec. gray. It is about eight and three-fourth times as heavy as water. 8750. it is ductile and malleable, when either cold or hot. Its melting point is somewhat under redness, and its point ef LEAD. 87 vaporization, under that at which mercury boils. It is pre- Chap. ni. cipitated from its solutions by zinc in the metallic state. It forms but one oxide, which may be obtained readily by combustion. This oxide has a greenish-yellow colour. It possesses all the properties of a salifiable base, and the salts, which it forms, have generally a white colour.* Lampadius has lately discovered a new metal in awodani- mineral from Hungary, supposed to have been a cobalt J1™^^! ore. He has given it the name of Wodanium. It occurs in e(j meUi. the Hungarian mineral to the amount of 20 per cent, asso- ciated with sulphur, arsenic, iron and nickel. This new metal has a bronze yellow colour. It possesses its proper- malleability, and has a hackly fracture. It is not tarnishedties- by mere exposure to air; but when heated, it is converted into a black oxide. It is about eleven and a half times as Spec grav. heavy as water, f SECTION VIII. OF LEAD. I. Lead may be obtained pure by the following process: Lead; how Dissolve the lead of commerce in nitric acid, and preeipi- obta,ned tate the solution by means of sulphuric acid. Separate the precipitate thus formed; and, after being washed and dried, mix it with two or three times its weight of black flux, and expose it to a red heat.—When sulphuric acid is added to a nitric solution of impure lead, a pure sulphate of lead preci- pitates. The lead is obtained from this sulphate in conse- quence of the heat to which it is exposed, which drives off the sulphuric acid and oxygen. II. Lead is obtained, in the large way, by a very different How ob- process: The ore called galena (sulphuret of lead) is sepa- J*""*1 in rated from impurities as far as possible, and then pulverized way. and washed. It is next roasted in a reverberatory furnace; taking care to stir it about, in order to expose all its surfaces to the air. When it begins to soften, it is to be mixed with charcoal, and the mixture stirred, while the heat is increas- ed gradually. After some time the lead in the metallic state begins to run, and passes through holes in the bottom of the furnace into a recipient below. The metal is then cast in • Annals of Philosophj, (Feb. 1819) p. 108, et seq. f Ibid. (March 18191 p. 232. 88 BASIFIABLE COMBUSTIBLES. Book I. Division I. Lead oc- curs native usually as a sulphuret. Properties of lead. iron moulds, so as to form the oblong masses, known in commerce by the name of pig lead. III. The most abundant ore of lead is galena (sulphuret of lead). The metal occurs also in the state of oxide, and in combination with acids. IV. Lead has a bluish white colour, and, after being newly melted, a bright surface, which soon tarnishes. It has a perceptible taste, and a peculiar smell upon friction. It is very soft and malleable; but its ductility is not very great. Its fusing point is at the temperature of 612°; and when subjected to a greater heat, in close vessels, it boils and rises in the form of vapour. V. It is somewhat less than eleven and a half times as heavy as water. VI. Lead combines in two proportions with oxygen, and forms protoxide and peroxide of lead. Litharge is an impure protoxide of lead, and will be described immediately after the protoxide. Red lead is a mixture of the two oxides of lead, and will be noticed after the peroxide. All these oxides, when vitrified by fusion, are found very use- ful in purifying silver and gold. When in fusion, they have the property of oxidizing, and combining with, all the inferior metals. Hence, if impure silver or gold be melted with a portion of lead, in a shallow cup called a cupel, made of ashes and burnt bones, and the heat continued for some time; the lead becomes oxidized, and, after vitrification, com- bines with the contaminating metals and sinks into the cupel; while the silver or gold remains behind in a pure state. This process, from the name of the cup employed, it called cupellation—The oxides of lead will now be consi- dered individually. I. Protoxide of Lead or Massicot. Protoxide 1. This oxide may be obtained by dissolving lead in nitric of lead; its ac'1(j? so as to form a colourless solution, and precipitating it by means of carbonate of potash, added in excess. The precipitate, after being washed and dried, and exposed to a red heat, consists of the oxide in question. 2. Protoxide of lead is of a yellow colour. It has no taste; and is insoluble in water, but dissolves in acids and in pot- ash. When exposed to a gentle heat, it melts into a yellow semi-transparent brittle glass. 3. It is composed of Lead 104 Oxygen 8 Spec. grav. 11-352. Lead forms with oxy- gen, 1. Protox- ide. 2. Litharge. 3. Peroxide. 4. Red ox- ide. Vitrified oxides of lead used in cupella- tion. prepara tion Properties. Composi- tion. 112 LEAD. gg 4. The massicot of commerce appears to be this oxide; but Chap. in. it is prepared in a different manner from that just described, w ~— L<-ad is kept melted, and the pellicles which form on its protoxide surf.ice are successivelv removed, until at last, the whole oflea<' its of the metal has undergone this conversion. The substance tion. thus formed is next exposed, in an open vessel, to heat, and stirred, until it assume a yellow colour: by this manage- ment it becomes converted into massicot. The pellicles, when first obtained, are a mixture of metallic lead and protoxide. By the subsequent exposure to heat and stirring in an open vessel, the metallic portion absorbs oxygen, whereby the whole is converted into protoxide. II. Semi-vitrified oxide of Lead, or Litharge. 1. Semi-vitrified oxide of lead is formed during the pro- 1 Litharge; cess for separating from lead, a portion of silver, with ,ts.prepa" which, in larger or smaller amount, the metal is usually combined. The process consists in this: The lead is placed upon a large fl.it dish called a test.* The flame of a blast furnace is made to act upon its surface; the effect of which is to convert the lead into a semi-vitrified substance; part of which is blown off the test, while the remainder sinks into it. Whatever portion of silver the lead may have con- tained, remains unaltered on the test. The semi-vitrified substance is this oxide of lead, commonly called litharge. 2. Semi-vitrified oxide of lead appears to be composed Consists of of scales, partly of a red, and partly of a golden-yellow co- Proto^1,,e> lour. It is found to consist of protoxide of lead, combined with car- with a small portion of carbonic acid. bonic a?id- 3. Semi-vitrified oxide of lead or litharge has several uses tharge in in the arts. It is employed in the glazing of pottery; and the arts; by painters to render linseed oil more drying. It enters as a component part in some kinds of glass; in the manufac- ture of which, it is useful by facilitating fusion. 4. It is also very useful in pharmacy. It constitutes the and in phar- bases of a number of plasters, which unquestionably are macv- useful in abating inflammation, and as drying applications. III. Peroxide of Lead. 1. This oxide may be prepared by causing chlorine gas 3 Perox- to pass into a vessel, partly filled with water, and contain-,deoflea.v»«ml. which consists of this Qxide# Its proper- 2. Peroxide of lead is a very fine light tasteless powder ties. 0f a fiXa-brown colour. It is not acted upon by sulphuric or nitric acid. It decomposes hydrochloric (muriatic) acid, its hydrogen being absorbed, while its chlorine is evolved. When heated, it gives out half its oxygen and is converted into protoxide. Composi- 3. it is composed of Uon- T J 1,^A Lead 104 Oxygen 10 120.—So that it appears that this oxide contains twice as much oxygen as the pro- toxide. IV. Red oxide of Lead, Minium, or Red Lead. i Redox- 1. Red oxide of lead may be obtained by the following prepara-d: Process: Expose massicot, ground to fine powder, for forty- tion. eight hours to heat, and let the flame of a furnace act upon its surface, while it is constantly stirred. The massicot ah- sorbs oxygen and is converted into red oxide of lead. Properties. 2. Red oxide of lead is a very heavy powder of an in- tensely red colour. It has no taste. When heated to redness, it gives out oxygen, and gradually melts into a dark brown coloured glass. Red lead of 3. The red lead of commerce is found to contain, besides commerce, red oxide of lead, some protoxide, together with sulphate redVide.6 an{^ hydrochlorate (muriate) of lead, and silica. When se- parated from these substances, it was found to be com- posed of Lead 208 Oxygen 24 232.—Hence it would ap- pear that red oxide of lead is an intermediate oxide, con- taining three times as much oxygen, united to twice as much The red ox-lead, as the protoxide. But the results obtained by the ac- pounded of ?'on °*" acids upon this oxide, favour the supposition that the protox- it is a compound of protoxide and peroxide, rather than a oxIdT1 PCr' Pecu^ar oxide. Thus if nitric acid be poured upon the red oxide of lead, a portion only is dissolved, which proves to consist of protoxide: the other portion, not attacked by the acid, is found to be peroxide. Now this separation into pro- toxide and peroxide always takes place, when the attempt is made to dissolve red oxide of lead in acids. Uses of the 4. Red oxide of lead as a paint is extensively used in the red oxide. arts# Qf aU the oxi(Jes Qf lead> jt jg preferred as a flux in fa manufacture of glass. TIN. 91 VII. Lead combines in one proportion with chlorine and Chap, hi. forms chloride of lead. Lead forms 1. Chloride of lead (horn lead) may be formed by precipi- °.ne Ro- tating a solution of nitrate of lead by chloride of sodium n e (common salt). The precipitate obtained, by being melted, is converted into this chloride. 2. Chloride of lead is a semi-transparent substance of a Its proper- greyish-white colour, having some resemblance to horn.tiei- When heated in the open air, it evaporates in the form of a white smoke; but inclose vessels, it remains fixed even at a red heat. 3. It is composed of Lead 104 Chlorine 36 140 VIII. Lead is capable of forming an iodide by means of Iodide of heat. It has a fine yellow colour. Its exact composition islead- not known. IX. Phosphuret of lead may be formed by dropping bits Phosphu- of phosphorus into melted lead. It has a silver-white colour,ret with a shade of blue. X. Lead combines with sulphur and forms sulphuret of Sulphuret lead. It occurs abundantly native under the name of cja-ot ,lead> or lena. It may, however, be formed artifically, by dropping sulphur into melted lead. It is a brittle, brilliant substance of a deep blue colour. It is much less fusible than lead. It is composed of Lead 104 Sulphur 16 120 XL The only important alloy which lead forms with the Alloy of metals already described is that with antimony. When itlead and contains about sixteen parts of lead united with one of an- *" timony, it constitutes the metallic compound, of which prin- ters* types are made. XII. The preparations of lead, when taken into the sto- Lead,a mach, prove poisonous, poison. SECTION IX. OF TIN. I. Tin may be obtained pure, by boiling the tin of com- Tin; how merce, in nitric acid, for some time, and heating strongly obtained 02 BASIFIABLE COMBUSTIBLES. Book I. the white powder thereby formed, in contact with about Pi"™» '• one fourth of its weight of charcoal powder, in a covered crucible lor half an hour. . How ob- H. This metal is obtained from its ores, bv fusion with £'oeresfr°m powdered charcoal. The charcoal separates the oxygen of the ore; and the sulphur, when that is present, is driven off. Ores of tin, III. The ores of tin are the sulphuret or tin pyrites, and where two oxides, called tin stone and wood tin. In Europe,they found- are found abundantly in particular districts in Germany, Spain and England. They are found abundantly also in some parts of Asia. In South America they occur, but only in small amount. Pro ertics Iv« Tin has a fine vv*"te colour like silver, and conside- ofT"' rable brilliancy, when free from tarnish. It has a slightly disagreeable taste, and a peculiar smell when rubbed. Its hardness is between that of gold and lead. It is very mal- leable, but does not possess much ductility. It is flexible and produces a crackling noise when bended. In air it loses its lustre, and becomes of a greyish black colour. Under water, at the common temperature of the atmosphere, it remains unaltered. Its melting point is at the tempera- ture of 442°. Spec. grav. V. Tin is nearly seven and one-third times as heavy as 7291. water. Tinf.rms VI. Tin combines in two proportions with oxygen, and two oxides. forms protoxide and peroxide of tin. l. Protox- 1. Protoxide of tin may be obtained pure by adding pot- •de. ash, in excess, to a solution of tin, in hydrochloric (muriatic) acid, formed by the assistance of heat. A white powder falls, part of which is redissolved; what remains is protoxide of tin. Its proper- 2. Protoxide of tin has a dark grey colour, and some ties. metallic lustre. It has no taste. It is soluble in acids and in solutions of the principal salifiable bases. When heated it takes fire, undergoes combustion, and is converted into the peroxide. When in solution, the same conversion takes place by the absorption of oxygen. 3. It is composed of Tin 59 Oxygen 8 67 s. Perox- 1. Peroxide of tin may be formed by heating tin in strong ide. nitric acid. A violent effervescence takes place, and the whole of the metal is converted into a white powder, which consists of this oxide. It may be obtained also by heating tin very violently in an open vessel. The metal catches fire, and the product of the combustion is this oxide. TIN. 93 2. Peroxide of tin, when pure, has a yellow colour; but Chap. ill. very often it is obtaine I white, which is owing to the pre- lls proper. sence of water. It combines with both acids and salifiable ties. basts. 3. It is composed of Tin 59 Oxygen 16 75.—So that it contains twice as much oxygen as the protoxide. VII. Tin combines in two proportions with chlorine, and Tin forms forms proiochloride and perchloride of tin. rides*10 1. Protochloride of tin may be obtained by evaporating, i proto- to dryness, the hydrochlorate (muriate) of tin, and fusingchlonde- the dry mass in a close vessel. 2. It has a grey colour and the resinous lustre and frac- its proper- ture. When it comes in contact with water, this liquid istie9, decomposed; and the chloride is changed into a hydrochlo- rate (muriate); when heaied in chlorine gas, it undergoes combustion, and is converted into the perchloride. 3. It is composed of Tin 59 Chlorine 36 95 1. Perchloride of tin (fuming liquor of Libavius.—Oxy- 2. Perchio- muriate of tin) may be formed by distilling, at a moderate ride- heat, a mixture of six parts of tin, one part of mercury, and thiru -three parts of perchloride of mercury (corrosive sub- limate). At first a colourless liquid passes into the receiver; but afterwards there suddenly rushes in a white vapour, which condenses, in the receiver, into a fuming liquid: this liquid is perchloride of tin. This same chloride is obtained by the combustion of tin in chlorine gas. When introduced into it, the metal undergoes this process and the product is the chloride in question. 2. Perchloride of tin is a colourless liquid like water, its proper- When exposed to the air, it fumes violently, owing to theties- avidity with which it absorbs moisture. 3. It is composed of Tin 59 Chlorine 82* 141.—So that this chlo- ride contains considerably more than twice as much chlorine as the protochloride. The chlorides of tin do not admit of any exact comparison as to composition. VIII. Iodide of tin may be formed by bringing the melt- iodide of 94 BASIFIABLE COMBUSTIBLES. Book i. ed metal in contact with the vapour of iodine. It is a very Divi3ion '• fusible substance of a dirty orange colour. When it comes in contact with water, it decomposes that liquid, and is con- verted into hydriodic acid and oxide of tin. Phosphu- IX. Phosphuret of tin may be formed by dropping phos- ret phorus into melted tin. It has the colour of silver, and its filings resemble those of lead. When thrown upon hot coals, the phosphorus, which it contains, catches fire. It is com- posed of Tin 59 Phosphorus 10* 69 Tin forms X. Tin combines in two proportions with sulphur, and reu.8UlphU"forms sulphuret and bisulphuret of tin. l. Suiphu- 1. Sulphuret of tin may be obtained by fusing tin with ret# sulphur, reducing the resulting mass to powder, and fusing it again, with another portion of sulphur; taking care to keep it at a temperature sufficiently high to drive off the superabundant sulphur. Its proper- 2. This sulphuret has a lead colour, and the metallic lus-1 tie8- , tre. When acted upon by hydrochloric (muriatic) acid, it is converted into oxide of tin and hydrosulphuric acid (sul- phuretted hydrogen.) 3. It is composed of Tin 59 Sulphur 16 75 2. Bisui- 1. Bisulphuret of tin, formerly called mosaic gold (aurum phuret. mosaicum) may be obtained by exposing a mixture of twelve parts of tin, seven parts of sulphur and three parts of hy- drochlorate of ammonia (sal ammoniac) to a strong heat, for eight hours, in a black lead crucible, to which is luted a vessel to receive the sublimed product. This sulphuret will be found sublimed. Its proper- 2. Bisulphuret of tin, when pure, consists of light scales t,es- of the colour of gold. When heated it lets go part of its sulphur, and is converted into the simple sulphuret. It is insoluble in water, and is not acted upon by hydrochloric (muriatic) or nitric acid. 3. It is composed of Tin 59 Sulphur 32 91.—So that it is pro- perly entitled to the name of bisulphuret; as it contains twice as much sulphur, as the simple sulphuret. COPPER. 95 XL The following are the only alloys of tin with the Chap. hi. metals already described, that deserve to be mentioned. AMoyTof 1. An alloy of tin and antimony constitutes the metallic tin, with plates upon which music is engraved. antimony; 2. Tin and iron are not very readily combined, so as to with iron; form an alloy; but the formation of tin plates affords suffi- cient proof that there is some affinity between them. Tin plate is made by dipping into melted tin, thin plates of iron, made thoroughly clean, first by rubbing them with sand, and afterwards by steeping them in water acidulated by bran or sulphuric acid. The tin gives a coating to the iron, which it renders uniformly white. 3. An alloy of tin and zinc constitutes the principal part with zinc; of some species of pewter. 4. Tin and lead, united in different proportions, consti- and with tute plumber's solder, as well as the more common kinds ,ead- of pewter. Tin foil always contains a portion of lead. XII. Tin has many uses. The covering which it affords Uses of tin. to iron and copper vessels, makes it of great importance to mankind. XIII. Tin, in a state of powder, is sometimes used in Medical medicine. In large doses, it is considered very efficacious uses- for expelling the tape worm. SECTION X. OF COPPER. I. Copper may be obtained pure by the following pro- Copper; cess: Dissolve the copper of commerce in strong hydrochlo- how obtain- ric (muriatic) acid. Immerse into the solution thus formed,e pure" diluted with water, a polished piece of iron. The copper is precipitated in the metallic state. The precipitate, after being washed and dried, is pure copper. II. The copper of commerce may be obtained from its How ob- ores, by first pounding and washing them; and afterwards, tained from if they contain sulphur, subjecting them to the operation of [hVTarge roasting for several successive times. They are then to be way. melted into a mass. After the copper is obtained) in a certain degree of purity, by these processes, it is fused hastily with three times its weight of lead. This latter metal dissipates, or separates in scoriae, the sulphur, arsenic, iron, and other foreign substances, with which it may be contaminated. It is afterwards subjected to a second fusion, by which other impurities are made to rise to the surface, in the form of 96 BASIFIABLE COMBUSTIBLES. Book I. Division I How found native. Properties •f copper. Spec. grav. 8 895. Copper forms two oxides. 1. Protox- ide. Its proper- ties. 2. Perox- ide. Its proper- ties. Copper forms two ehlorides. scoriae. The purity of the metal is then tested by the im- mersion of a rod of iron into the melted mass: the iron becomes coated with copper, the quality of which may be readilv ascertained upon examination. III. Copper is found abundantly, in different parts of the world, in the states of sulphurets, oxides and salts. IV. Copper has a fine red colour, and a great deal of brilliancy. It possesses a nauseous and styptic taste, and a disagreeable smell when rubbed. It is very malleable, and possesses considerable ductility. Its hardness exceeds that of silver. It is not altered under water. Its fusing point is at 27° of Wedgewood; and when exposed to a greater heat, it evaporates in visible fumes. When subjected to a violent heat, such as is produced by the combustion of a mixture of oxygen and hydrogen gases, it takes fire and burns with great brilliancy, emitting a very intense green light. V. It is very nearly nine times as heavy as water. VI. Copper combines in two proportions with oxygen, and forms protoxide and peroxide of copper. Both these oxides enter into the composition of salts. 1. Protoxide of copper may be obtained by putting piecei of rolled copper into a solution of copper in hydrochloric (mtt« riatic) acid, contained in a phial, which must then be closely corked. After some time, the colour of the solution, which is at first green, becomes converted into a dark brown. Add, to the liquid as it now stands, a solution of potash. A preci- pitate immediately falls, which consists of protoxide of copper. 2. This oxide is red when native; but when formed arti- ficially, it has a yellow colour. It is composed of Copper 64 Oxygen 8 1. Peroxide of copper may be formed by keeping red hot for some time, in an open vessel, the scales which form on the surface of copper, when exposed to a red heat. By being thus treated, the scales absorb oxygen and are converted into the peroxide in question. 2. This oxide is a tasteless black powder, soluble in acids. It is composed of Copper 64 Oxygen 16 80.—So that it is ob- vious that this oxide of copper contains twice as much oxygen as the protoxide. VII. Copper combines in tivo proportions with chlorine, and forms protochloride and perchloride of copper. COPPER. 97 1. Protochloride of copper may be formedbyheatingaCHAP.nl. mixture of two parts of perchloride of mercury (corrosive i. p,.oto. sublimate) and one part of copper. The chlorine separates chloride. from the mercury, and combines with the copper, so as to form this chloride. 2. This chloride has an amber colour, and a certain de- its proper- gree of transparency. In close vessels it is not decomposed *>«• at a red heat; but at the same temperature in the open air, it dissipates in white fumes. It is composed of Copper 64 Chlorine 36 100 1. Perchloride of copper may be formed by evaporating 2. Perehhv prrhydiochlorate (green muriate) of copper to dryness, at a ride. heat not exceeding 400°. The hydrogen of the acid, and the oxvgen of the oxide of copper are driven off, and what remains consists of this chloride. -2. Perchloride of copp«r has a brownish yellow colour, its proper- When exposed to the air, it absorbs moisture, and becomes,ties- first white and then of a green colour. Heat drives off part of iis chlorine, and converts it into the protochloride. It is composed of Copper 64 Chiorine 72 U6.—So that it is ob- vious that this chloride of copper contains twice as much chlorine as the protochloride. VIII. Iodide of copper may be formed by heating its iodide of constituents together. It has been but very slightly examin- copper. ed. Its composition is not known. IX. Phosphuret of copper mayT be formed by throwing Phosphu- pieces of phosphorus upon red hot copper. This phosphuretret* is neither ductile nor pulverizable. It is harder than iron, and much more fusible than copper. When exposed to the air, it loses its lustre, and falls to pieces; the copper being oxidized, and the phosphorus converted into phosphoric acid. X. Sulphuret of copper may be formed, by exposing, in Sulphuret. a glass receiver, a mixture of eight parts of copper filings, and three parts of flowers of sulphur, to the heat of burning coals. The mass first melts, and then explodes gently; after which, when the combination is complete, it becomes red hot. It is a brittle substance, of a deep blue-grey colour. It is much more fusible than copper. It is composed of Copper 64 Sulphur 16 N 80 98 BASIFIABLE COMBUSTIBLES. Book I. XL The following alloys of copper, with metals already n'v'"on r described, deserve to be mentioned. Alloys of l. The variety of iron, which is brittle when red hot, and Slron; from ^ circumstance called hot short, is supposed to de- rive its peculiar qualities from the presence of copper. with zinc; 2. The alloy of copper and zinc constitutes different kinds and of brass. It is formed, by the manufacturer, by melting together, granulated copper, the native ore called calamine, and a proportion of charcoal powder. The fusion must be kept up for five or six hours. By this mode of proceeding, the zipc of the calamine becomes deoxidized, and combines with the copper. The most intimate compound of these me- tals is in the proportion of 64 parts of copper, to 33 parts of zinc. Brass is much more fusible than copper. It is malleable when cold, if not containing too large a proportion of zinc; but brittle when heated. It possesses ductility, and may be drawn out into very fine wire. An alloy of copper and zinc, in which the zinc predomi- nates in a certain degree, constitutes pinchbeck, or prince Rupert's metal. with tin. 3. The alloy of copper and tin, united in different pro- portions, constitutes the metals of which bells, bronze, can- nons and the mirrors of telescopes are made. The tin in these alloys diminishes the ductility of the copper, but in- creases its hardness, fusibility and sonorousness. Bronze and the metal of which cannons are made, are composed of from eight to twelve parts of tin, combined with one hundred parts of copper. Bell metal contains about one-fourth of its weight of tin. The alloy for the mirrors of telescopd is composed of two parts of copper united to one part of tin. Process of 4. In consequence of the ease, with which copper may tinning cop- be alloyed with tin; the former may be, very readily, cover- ed. t ' "ed with a coating of the latter. A coating of tin is very fre- quently given to copper vessels, intended for use in cooking, to guard against the bad effects of the copper. The process of tinning copper is conducted in the following manner. The vessel to be tinned has its interior surface scraped very clean with an iron instrument, and then rubbed with hydrochlo- rate of ammonia (sal ammoniac). It is then heated, and a little pitch thrown into it, which is allowed to spread. While in this state of preparation, the tin is rubbed over the whole surface, which immediately assumes a silvery white colour. The previous steps in the process are neces- sary to render the copper perfectly clean; for the tin will not adhere, if the surface of the copper be in the least de- gree tarnished. BISMUTH 99 Most generally it is not tin, but an alloy of tin and lead, Chap. hi. which is used to give this coating to copper vessels- It was supposed probable, therefore, that the latter metal might be dissolved, when such vessels were used for preparing food, more particularly acid food. Experiments have been made to ascertain this point; and it appears that the presence of the tin prevents altogether any solution of the lead. Ac- cordingly copper vessels, tinned with this alloy, may be em- ployed for the preparation of food without hazard. XII. Metallic copper is not employed in medicine. But Metallic in different states of combination, it furnishes the phvsi- CO('i,er' not cian with several valuable preparations. These will be no- dicine. ticed hereafter under distinct heads. SECTION XI. OF BISMUTH. I. Bismuth may be obtained by the following process: Bismuth; Dissolve the bismuth of commerce in strong nitric acid,how obta,1>- and precipitate the solution by adding water. Wash the precipitate, which consists of oxide of bismuth; and after being dried, expose it for twenty minutes to a dull red heat, mixed with black flux. The precipitate becomes deoxidized, and a button of pure bismuth is obtained. II. Bismuth is usually obtained from its ores, by fusion How ob- with one-eighth of their weight of white flux. The sulphur *aine',from and oxygen, which may be present, are separated, and the pure bismuth remains behind. III. Bismuth has been found in Sweden, France and Eng- Where land; but it occurs in by far greater abundance in Saxony foun,J- than in any other country. It exists usually in the state of sulphuret or of oxide. IV. Bismuth has a white colour with a tint of red. It is Properties tasteless and inodorous. In texture, it is composed of bril- of bismuth liant plates, adhering to each other. When exposed to the air, it suffers a slight tarnish, but remains unaltered under water. It is neither malleable nor ductile. In hardness it is inferior to copper. Its fusing point is at the temperature of 476°; and if the heat be increased beyond this degree in close vessels, the metal may be distilled over. V. It is somewhat less than ten times as heavy as water, spec. gr«v. VI. Bismuth combines with oxyrgen in one proportion .9*822. only, and forms oxide of bismuth. formsUbut 1. This oxide may be formed by keeping bismuth in a one oxide; state of fusion, exposed to the open air. A pellicle forms on 100 BASIFIABLE COMBUSTIBLES Book I. the surface of the metal, which is quickly succeeded by an- Dirisionl. other. as soon as the first is removed. By continuing the fu- sion, the whole metal may at last be converted into these pellicle3. They are then to be heated, with agitation, lor some time in an open vessel; by which treatment they absorb oxygen and are converted into the oxide in question. Oxide of bismuth may be formed also by combustion. When bismuth is exposed to a strong red heat, it catches fire, and burns with a faint blue flame; the product being this oxide. 2. Oxide of bismuth is a tasteless insoluble y ellow pow- der. It is composed of Bismuth 71 Oxide 8 79 and but one VII. Bismuth combines in one proportion with chlorine,^ chloride. and forms chloride of bismuth. 1. Chloride of bismuth, formerly called butter of bis- muth, may be obtained by keeping in a state of lusion for several hours, a mixture of perchloride of mercury (corro- sive sublimate) and bismuth. The chlorine is transferred from the mercury to the bismuth, with which it forms the chloride in question. The mercury, in the metallic state, sinks to the bottom of the vessel. 2. This chloride is opaque, of a greyish yellow colour, and granulated texture. In close vessels it does not sublime, even at a red heat. It is composed of Bismuth 71 Chlorine 36 107 Iodide of VIII. Iodide of bismuth may be formed by heating its bismuth, constituents together. When thus formed, it is an in- soluble substance, of an orange yellow colour. It has not been analyzed. Sulphuret. IX. Sulphuret of bismuth may be formed by fusing together its constituents. It is a very brittle and fusible substance, of a bluish grey colour. It is composed of Bismuth 71 Sulphur 16 87 SECTION XII. OF MERCURY. Common name, Quicksilver. Mercury; I. Mercury mav be obtained pure, bv exposing, to an tiow obtain- l ji_ #• ^ ed pure, obscure "d heat, a mixture of two parts of native sulphuret MERCURY. 101 of mercury (cinnabar) and one part of iron, contained in a Chap. hi. stoneware retort, furnished with a receiver filled with- water. The sulphur combines with the iron, and the mercury appears in the metallic state. II. Mercury, either native or mineralized, has been Where found in Spain, Germany, and Hungary; in China and infound* Peru. The most productive mines are those of Idria, and of Almadcn, near Cordova, in Spain. It occurs, forming an amalgam with silver; as a sulphuret (cinnabar), and as a chloride (horn mercury). III. Mercury has a white colour, resembling that of Properties silver, and possesses considerable brilliancy. It is liquid ofmerc»"'y- at the common temperature of the atmosphere; in which respect it differs from all other metals. It solidifies at the temperature of 39° below zero, of Fahrenheit's scale, and becomes much heavier. Its boiling point is at the tempera- ture of 656": accordingly it may be subjected to distillation, whereby it may'be freed from admixture of contaminating metals. It is not altered by being kept under water, and suffers a slight tarnish only by exposure to the air. IV. It is somewhat more than thirteen and a half times Spec. gray. as heavy as water. 13 568. V. Mercury combines in two proportions with oxygen, Mercury and forms protoxide and peroxide of mercury. foi:ms tw0 PROTOXIDE OF MERCURY. Formerly called, Ethiops per se. j(je 1. This oxide may be formed by digesting protochloride How pre- of mercury (calomel) in a solution of potash. A powder is Parcd- thereby formed, which consists of the oxide in question. It may be formed also by subjecting mercury, contained in a phial, to constant agitation. It was obtained in this way by the earlier chemists; and, from the manner of the process, was called ethiops per se. 2. Protoxide of mercury is an insoluble powder of a black colour and coppery taste. It is destitute of metallic lustre. It is composed of Mercury 200 Oxygen 8 208 3. Mercury becomes slowly converted into protoxide by Formed contact with the atmosphere. When minutely divided, by a,8° V? tri' mechanical means, this conversion takes place much sooner; Wuh cer- in consequence of the great increase of surface exposed to tain sub" the influence of the air. Accordingly, whenever this metal8tances' is triturated with powders or viscid substances, it is con- verted into protoxide, which combines with the substance 102 BASIFIABLE COMBUSTIBLES. Several medicinal prepara- tions thus obtained. Book I. employed. By taking advantage of this circumstance, several Division I. important preparations of mercury are made. When the metal is triturated with carbonate of lime (chalk), until its metallic nature disappear it forms a preparation of the London college, under the name of quicksilver with chalk. In very nearly the same manner, the officinal preparation of the Dublin college, called quicksilver with magnesia, is prepared. When triturated with conserve of roses, and afterwards mixed with some powder, such as of liquorice or of starch, to give the mass a proper consistence, it con- stitutes the preparation of which the officinal mercurial pills are formed. Mercurial ointment, the most common prepa- ration of mercury for external use, consists of this oxide, formed, and combined, by trituration with lard. PEROXIDE OF MERCURY. Common name, Red Precipitate of Mercury. 1. This oxide may be obtained by dissolving mercury in nitric acid, evaporating the solution to dryness, and exposing the dry mass to a heat gradually increased, until it become converted into very red scales. These scales consist of the oxide in question. 2. The Edinburgh college directs, for the preparation of this oxide, four parts of purified mercury to be dissolved in three parts of diluted nitrous acid. The solution thus form- ed is to be evaporated to dryness, and the mass obtained ground to powder. This powder is to be exposed, in a sand bath, to a gradually increased heat; until the whole is con- verted into very red scales. In both these processes the metal is peroxidized at the expense of the acid, which is partially decomposed. 3. This oxide may be prepared also by exposing mercury, contained in a glass vessel, with a large bottom and a narrow mouth, to a greater heat than 656°, or the boiling point of mercury. The metal is converted into vapour, and, in that state, is oxidized by the atmospheric air, and condensed. By a continuance of the heat, for several months, the mercury is ultimately converted into a red powder, which consists of the oxide in question. When the peroxide is prepared in this manner, it is called calcined quicksilver by the London and Dublin colleges. It possesses, however, no superiority over that obtained by the action of nitric acid, when care- fully prepared. The peroxide obtained by the method of the Edinburgh college is called the red oxide of quicksilver by nitric acid. 4. Peroxide of mercury, or red precipitate, has a bright • scarlet colour, and an acrid and disagreeable taste. It is somewhat soluble in water. 2. Peroxide. How ob- tained. Prepara- tion for use in medicine. Another method. Peroxide described. MERCURY. 103 5. It is composed of Chap. HI. Mercury 200 Oxygen 16 216—so that it appears, that this oxide contains twice as much oxygen as the protoxide. 6. Peroxide of mercury is a very useful preparation in Its medical medicine. It operates as a poison in the stomach, anduses> possi-ss^s the properties of an active caustic when applied to the skin. When mixed with a mild ointment, it forms one of the best applications for indolent and other ill-con- ditioned ulcers. VI. Mercury combines in two proportions with chlorine, Mercury and forms protochloride and perchloride of mercury. forms two 11 J chlorides. PROTOCHLORIDE OF MERCURY. 1. p,.oto. Usual chemical names, Mild Muriate of Mercury—Sub-Muriate of Mercury, chloride, or Common name, Calomel. calomel. 1. Protochloride of mercury or calomel may be prepared How ob- by the following process: Dissolve in boiling nitric acid astained" much mercury as this solvent can take up. Make a solution of chloride of sodium (common salt), containing half as much of this chloride, as the nitric solution does of mercury. Into the solution thus formed, pour cautiously the boiling nitric solution of the mercury. This addition causes a white precipitate to fall, which must be washed until the water employed comes off tasteless, and then dried on a filter. This precipitate consists of the chloride under considera- tion. It is formed in this process in consequence of a double decomposition. No sooner is the nitric solution of the mer- cury added to the solution of the chloride of sodium, than the mercury, being previously deoxidized, falls in combina- tion with the chlorine of the chloride, in such a proportion as to constitute the protochloride of mercury. The sodium of the common salt becomes oxidized, and combines with the nitric acid; so that, after the precipitated chloride is re- moved, the remaining liquid is a solution of nitrate of soda. 2. The Edinburgh college directs the following process Prepara- for preparing this chloride: Rub together in a glass mortar, tion for me- with a little water, four parts of pulverized perchloride of lca use" mercury (corrosive sublimate) and three parts of pure mercury, until all the metal is extinguished. Sublime the powder thus formed, after being dried, in an oblong phial only one-third filled, by the heat of warm sand. When the sublimation is finished, break the phial, and separate the red matter found near its bottom, and the white matter near its neck. Sublime the remainder a second time, grind it into a very fine powder, and wash it with boiling distilled 104 BASIFIABLE COMBUSTIBLES Book I. water. It is now pure protochloride of mercury or calo- Divimou I. mel ThU, 3. In the above process of the Edinburgh college, the tri- proces? ex-turation of the perchloride of mercury (corrosive sublimate) plained. wjth pure mercury, has the effect of decomposing the form- er, and enabling its chlorine to combine with the metallic mer- cury, as an additional quantity. What, therefore, was at first a perchloride becomes, in this way, converted into a proto- chloride. This conversion, however, is not entirely complete; and hence the necessity of sublimation. But even alter this measure is taken, there still exists, in the upper and lower parts of the vessel, in which the sublimation is performed, portions of perchloride not completely converted into the protochloride. These, therefore, are directed by the Edin- burgh college, to be separated from the middle portion, which is again sublimed as a measure of farther precaution. The other colleges, however, triturate in a mortar, the entire product of the first sublimation, so as to mix its several parts; and sublime it again, the Dublin college once, and the Lon- don college four times. The mode of proceeding of these colleges must be considered as equally good, in result, with that pursued by the Edinburgh college; and it has the ad- vantage of economizing the ingredients. It is very proba- ble that one sublimation, as pursued by the Dublin college, may be sufficient. At any rate, no unpleasant consequences would arise from the use of calomel, prepared in this way, if it be carefully washed; since, in this process, all adher- ing perchloride (corrosive sublimate), from its greater solu- bility, would be abstracted. Properties 4. Protochloride of mercury, or calomel, is an insoluble °fthie^d°" Powder of a dull white colour, and possessing very little taste. It is somewhat more than seven times as heavy as water. When acted upon by chlorine gas, it is converted into perchloride of mercury (corrosive sublimate.) 5. It is composed of Mercury 200 Chlorine 36 236 Thischio- 6. It would require volumes to recount the many valua- lmpoAantT kle applications of this chloride. It is suited to almost every medicine, case, in which the internal employment of mercury is indi- cated. It acts as a gentle purgative in most cases; but its most remarkable property is that of stimulating the secre- , tory organs, more parcicularly the liver. It is the prepara- tion of mercury most usually given to produce a salivation. In the venerv-tl dise-se, except in peculiar cases, no form of mercuiy can be substituted for it with advantage. MERCURY 105 PERCHLORIDE OF MERCURY. Chap HI. Usual Chem. names, Corrosive Muriate of Mercury.— Oxymuriate of Mercury. 2. Perchlo- Common name, Corrosive Sublimate. ride, orcor- . i -jlj- i • rosive subli- 1. This chloride may be obtained by dissolving peroxide mate; how of mercury in hydrochloric (muriatic) acid. The hydrogen obtamed- of the acid, and the oxygen of the oxide combine and form water; while the chlorine of the former, and the mercury of the latter unite to form the chloride. 2. The British colleges, for the formation of this chlo- Prepara- ride, direct the following process: Take of purified mercu- *,on for me- ry, four parts; sulphuric acid, five parts, and dried chloride of sodium (common salt) eight parts. Boil the mercury in the sulphuric acid, contained in a glass vessel, until the mass become dry; and then mix it, when cold, with the chloride of sodium. Sublime the mixture, in a glass vessel, with a heat gradually increased. The sublimed product is perchlo- ride of mercury. 3. In the process just given, the mercury, by being boiled Last pee. with the sulphuric acid, becomes oxidized at the expense cfs? *£* of part of the acid; while, with the remainder, it forms the compound called sub-sulphate of mercury. When the sub- sulphate is sublimed in a state of mixture with dry chloride of sodium (common salt), a double decomposition takes place; the chlorine of the chloride combines with the mer- cury of the sub-sulphate, and this compound sublimes; while the sulphuric acid unites with the sodium, previously converted to the state of soda, by the oxygen, which had been displaced from combination with the mercury. The residue of the sublimation is, therefore, a sulphate of soda (glauber salt.) 4. Perchloride of mercury, or corrosive sublimate, when Its proper obtained by sublimation, is a beautiful white semi-transpa- tie8* rent substance. It has an excessively acrid and caustic taste; and leaves, for a long time, a disagreeable, metallic, stvptic impression in the mouth. It is soluble in about twenty times its *> eight of cold water, and in twice its weight of boiling water. It is soluble in sulphuric, nitric or hydrochlo- ric (muriatic) acid; and may be obtained, from solution in either, by evaporation unaltered. It is decomposed by so- lutions of potash or of soda, which throw down the mer- cury in the state of peroxide, of a yellow colour, becoming afterwards brick-red. 5. When ammonia is added to a solution of perchloride Forms a of mercury (corrosive sublimate), a white precipitate falls. Precipitate consisting of the perchloride, combined with a small pro- moma"1"1" portion of ammonia. This compound is usually called by chemists, a subpxymuriate of mercury-and-ammonia; it ip O 106 BASIFIABLE COMBUSTIBLES. Book I. the white calx of quicksilver of the London college, and is Divi9ion' employed medicinally only in the form of ointment. If named in conformity with the improved nomenclature, it ought, perhaps, to be called the ammoniated perchloride of mercury. 6. Perchloride of mercury is composed of Mercury 200 Chlorine 72 272.—So that it is evi- dent that this chloride contains twice as much chlorine as the protochloride. Its medical 7. Perchloride of mercury or corrosive sublimate is so uses. very active a substance, as to be properly classed among poisons. Nevertheless it may be employed internally, in small doses, for the cure of diseases. It has been given for the cure of the venereal disease; but it does not deserve the same confidence as the protochloride (calomel); neither is it so innocent or manageable. As an external application, it is useful in solution, to destroy fungous flesh, to cleanse ulcers and to cure herpetic eruptions; but the strength of the solution must be carefully attended to. A large portion of ulcerated surface cannot be washed with it without dan- ger. The solution is very useful also in ulcerations of the throat, and in promoting the desquamation of eruptions. Poisoning 8. When this chloride is taken, whether by accident or bythischio- design, in too large quantities, it occasions very dreadful clibed. consequences. It causes a burning heat and sense of stric- ture in the throat; excruciating pain in the stomach; nausea and vomiting, attended by violent efforts.* It has been as- certained by late experiments, that the most effectual anti- dote to this poison is albumen or white of the egg. This latter substance, given in large quantities, beat up with wa- ter, combines with the poison, with the effect of rendering it nearly inert.j Mercury VII. Mercury combines in two proportions with iodine. forms two The protiodide has a yellow colour, and the periodide, a 1 es' beautiful red. They are both soluble in water. Phosphuret VIII. Phosphuret of mercury may be formed by distil- of mercury. Hng a mixture of peroxide of mercury with phosphorus. The oxide parts with its oxygen, which acidifies a portion of the phosphorus; and after being thus reduced to the me- tallic state, combines with the remainder of this combusti- ble, to form the phosphuret in question. It has a black colour and a pretty solid consistence. When exposed to the air it exhales vapours of phosphorus. * See Nancrede's edition of Orfila on Poisons, p. 26. f Ibid. p. 39, et seq. MERCURY. 107 IX. Mercury combines in two proportions with sulphur, Chap, in. and forms sulphuret and bisulphuret of mercury. Mercury forms two SULPHURET OF MERCURY. sulphurets. Common name, Ethiops Mineral. 1. This sulphuret may be formed by adding mercury, 1. Sniphu- slowly, to its own weight of melted sulphur; stirring at the pf'1^ same time the mixture constantly, until the union be com- plete. It may be formed also by passing a current of hydro- sulphuric acid (sulphuretted hydrogen) through a solution of mercury in an acid. The precipitate which will appear is the sulphuret in question. 2. Sulphuret of mercury is a black powder, which re- Described mains unaltered in the air. When exposed to heat, it emits sulphureous fumes. It is insoluble in nitric acid, but dis- solves in a solution of potash; from which it may be preci- pitated unchanged by acids. It is composed of ' Mercury 200 Sulphur 16 216 3. This sulphuret has been used in medicine, as an alter- Its medical ative, in glandular and cutaneous diseases. But, withoutuses doubt, no effects can be expected from its use, which are not more certainly produced by other preparations of mer- cury. BISULPHURET OF MERCURY. Common names, Cinnabar.— Vermilion. 1. Bisulphuret of mercury may be obtained by subliming 2. Bisul- the simple sulphuret at a red heat. The sublimed product Phuret constitutes this sulphuret. 2. It is a tasteless insoluble substance of a fine scarlet Properties. colour. It is not altered by exposure to air. When heated it takes fire and burns with a blue flame. When in the form of a very fine powder, it is known in commerce by the name of vermilion. It is composed of Mercury 200 Sulphur 32 232.—Accordingly it con- tains twice as much sulphur as the simple sulphuret. 3. Bisulphuret of mercury was formerly much more em- Used in ployed in medicine than at present. It is sometimes used in medicine- fumigations for venereal ulcers of the nose and throat; and most usually produces a very prompt ptyalism. X. Mercury combines with most of the metals. These Amaiga» combinations are called amalgams. Only two of them will be mentioned. 108 BASIFIABLE COMBUSTIBLES. Book I. 1. The amalgam of zinc, composed of two parts of zinc, DlTl!,io"l and five parts of mercury, is found useful for promoting the of zinc: excitement of electrical machines. of tin. 2. The amalgam of tin is used for silvering the backs of looking glasses. The process is as follows: tin foil is spread upon a marble table, and mercury poured upon it, and in- corporated with a brush. The plate of glass, to be silvered, is then slid over the amalgam, so as to prevent the presence of air between it and the metal; and pressed down by weights. The superfluous mercury is thereby pressed out from under the plate; and by continuing the pressure for a certain length of time, a thin layer of the tin amalgam ad- heres to the surface of the glass. Mercury, XI. From what has already been said of some of its com- 'n'tiiTmate- Pounc^s» n iS verv evident that mercury constitutes one of ria niedica. the most important articles of the materia mtdica. In the progress of the work, however, several other important preparations of this metal will be noticed. SECTION XIII. OF SILVER. Silver; how I. Silver may be obtained pure by the following pro- obtained cess: Dissolve the silver of commerce in nitric acid, and precipitate the solution by chloride of sodium (common sjlt). Ignite the precipitate, after being washed and dried, with three times its weight of carbonate of potash (salt of tartar), mixed with a little charcoal powder. A button of pure silver will be obtained. How found. II. This metal is found in the state of alloy, with gold, antimony, arsenic and bismuth; as a sulphuret; in the form of oxide, called red silver ore; in the form of a chloride (horn silver); and combined with carbonic acid. It occurs in Bohemia, Norway and Transylvania. But by far the most productive mines of silver are those of South America. How ex- III. The most usual method of extracting silver is the fronts following: The ore is first pounded, then roasted and wash- ores. ed, and afterwards triturated with mercury under water. An amalgam of silver becomes in this way formed, which is washed and strained through leather. It is then subjected to distillation; whereby the mercury is driven off and the silver left pure. Properties IV. Silver has a white colour with a tint of yellow. It of silver, has no taste or smell. It possesses a good deal of brilliancy* Its hardness is intermediate between that of copper and gold* SILVER, • *\Q It is remarkably malleable and ductile. In the air it suffers Chap, hi. a tarnish, which is ascertained to be produced by sulphur. ~" Its melting point is at 22° of Wedgewood. When subjected to the heat produced by the combustion of a stream of oxygen and hydrogen gases, it burns rapidly with alight blue flame. V. Silver is about ten and a half times as heavy as water. Spec grav. VI. Silver combines with oxygen in one proportion only, Sil*°*7*" and forms oxide of silver. forms but 1. It may be obtained by dissolving silver in nitric acid,one oxida; and precipitating the solution by lime water. The precipi- tate obtained consists of this oxide. 2. Oxide of silver is a tasteless insoluble powder of a dark olive brown colour. It dissolves readily in nitric acid. When heated to redness, it is deoxidized and reduced to the metallic state. It is composed of Sdver 110 Oxygen 8 118 VII. Silver combines with chlorine and forms chloride and hut one of silver. cbloridc- 1. Chloride of silver (muriate of silver), formerly called horn silver, may be obtained by dissolving silver in nitric acid, and adding the solution thus formed to a solution of chloride of sodium (common salt). A precipitate appears which consists of this chloride. After it is separated, what remains is a solution of nitrate of soda. 2. Chloride of silver is a white substance, very insoluble Properties in water. When exposed to the air, it acquires a purple co- °.f.the chl°" lour. At a heat of 500° it melts; and upon cooling, assumes the form of a grey semi-transparent mass, having some re- semblance to horn. It is soluble in ammonia and in hydro- chloric (muriatic) acid. Both potash and soda in the state of carbonates produce its decomposition; but in the pure state, have no effect upon it. None of the acids are capa- ble of effecting its decomposition. When dissolved in am- monia, and mixed with running mercury, the silver gradually combines with the latter, and crystallizes into that beau- tiful appearance, called Arbor Dians or Diana's tree. The ammoniacal solution of this chloride when heated, deposites a powder, which is• oxide of silver combined with ammo- nia. This powder has the property of detonating when struck, and is hence called fulminating silver. 3. Chloride of silver is composed of Silver HO Chlorine 36 146 no Book I. Division I. Iodide of silver. Phosphu- ret. Sulphuret. Alloy of sil ver with copper, forms sil- ver coin. BASIFIABLE COMBUSTIBLES. VIII. Iodide of silver may be obtained by dropping an hydriodate into a solution of nitrate of silver. The hydno- die acid is decomposed; its iodine combines with the silver, so as to form the iodide in question; while its hydrogflB combining with the oxygen of the oxide of silver, formi water. It is an insoluble substance of a greenish-yellow co- lour, having considerable resemblance to chloride of silver. IX. Phosphuret of silver may be formed by melting to- gether equal parts of silver and phosphoric acid, along with one-eighth of their weight of charcoal. The phosphoric acid parts with its oxvgen to the charcoal; and thus reduced to phosphorus, combines with the silver. It is a solid sub- stance of a white colour and granular texture. It is decom- posed by heat; the phosphorus exhaling in fumes. X. Sulphuret of silver may be formed by melting toge- ther thin plates of silver and sulphur, laid alternately in a crucible. It occurs native of a deep violet colour. It is much more fusible than silver. It is composed of Silver 110 Sulphur 16 126 XI. The only alloy of silver with metals already describ- ed, which will be noticed, is that with copper. This alloy u harder and more sonorous than silver. It is white, and re- tains that colour, even when the proportion of copper ex- ceeds one half. Its hardness is greatest, when it contains about one eighth of its weight of copper. Silver coin con- sists of this alloy. The proportion of copper directed by dif- ferent nations to make their silver standard is various. The following table gives the proportion of pure silver, combin- ed with one part of copper, in the silver coin of several countries. COINS. Parta of pure lilver, eontbjafi with one of copper. Silver coin of the United States,...... 8*3 Britain,..........12*3 France,.......... 9* Spain,........... 8'7 SECTION XIV. OF GOLD. Gold; bow I. Gold may be obtained pure by the following process: obtained Treat native gold with aqua regia, until every thing soluble pure" be taken up. If any silver had been present, it remains behind GOLD. Ill in the form of an insoluble chloride (horn silver). Separate chap. in. the clear solution from this residue, and add to it a solu--------** tion of sulphate of iron, (green \ itriol): a precipitate falls, which consists of pure gold. After being separated and washed, it may be fused into a mass. II. Gold occurs native, only in combination with other How found, metals. It is alloyed by silver, copper, and sometimes iron. and where- In Europe, it is found in Hungary, Sweden, Norway and Ireland. In the tropical regions, where it is by far the most abundant, it occurs in Africa in the sands of rivers; in South America and in India. In the United States, it has been found in North Carolina. III. To separate gold from earthy or sandy matters, with How sepa- which it may be mixed, in the form of grains, in nearly a™^/1^. pure state; the method is to reduce the auriferous earth totainingit. coarse powder, and afterwards to place it upon a cloth with a long nap, where it may be subjected to the action of a stream of water. By this management, the greater part of the earthy and sandy particles are washed away; while those of the gold, by reason of their greater weight, remain be- hind entangled in the cloth. The particles, thus obtained, are disengaged from the cloth, and further purified by agitation with water; this acts by suspending the lighter particles, which may be drawn off from those which remain at the bottom. When the gold particles are brought to this state of purification, they are triturated with mercuryT in an iron vessel containing boiling water. An amalgam of gold is thereby formed; but it is still mixed with earthy matters. These may be separated by farther washings; and finally by laying the whole mass upon an inclined surface; from which the amalgam may be made to run by a little stirring, leaving the impurities behind. After the amalgam is thus obtained in a pure state, it is subjected to distillation; whereby the mercury is driven off in the state of vapour, and the gold is left behind. If it contain silver as it usually does, this metal may be separated by subjecting it, in very thin leaves, to the action of nitric acid. This acid dissolves the silver and leaves the gold untouched1. IV. Gold is a soft metal of a fine light yellow colour. It Properties is destitute of taste or smell. Its lustre is very considerable, of gold. It is the most malleable and ductile of all the metals. In the air or immersed in water, it does not lose its lustre, and is not in the least affected by these fluids. When subjected to a heat of 32° of Wedgewood, it fuses and assumes on the surface, a bright bluish green colour. V. Next to platinum, it is the heaviest substance known; Spec. grav. being more than nineteen times as heavy as water. t9'3 112 BASIFIABLE COMBUSTIBLES. Book I. VI. Gold combines in two proportions with oxygen, and Du.aonJL forms protoxide and peroxide of gold. Gold forms j. Protoxide of gold may be obtained by exposing per- l Protox-*' hydrochlorate (permuriate) of gold to heat, until it ceases ide. to give out chlorine. The chlorine appears in consequence of the decomposition of part of the hydrochloric acid; the corresponding hydrogen of the same acid combines with part of the oxygen of the peroxide, so as to reduce it to th state of protoxide; and thus the perhydrochlorate becomes a simple hydrochlorate. When caustic potash is added to this hydro- chlorate, it throws down the protoxide in the form of a powder. its proper- 2. This oxide is of a green colour. In a very short time t,es- it becomes s- parated into two parts. Two thirds of it are reduced to the metallic state; the oxygen from which, com- bining with the other third, converts it into peroxide. It is composed of Gold 200 Oxygen 8 208 2. Peroxide l. Peroxide of gold may be formed by dissolving the metal in a mixture of one part of nitric acid, and four parts of hydrochloric (muriatic) acid; and treating the heated so- lution by potash. A precipitate gradually appears, which must be washed carefully and dried; it consists of the per- oxide in question. Its proper- 2. This peroxide is a tasteless reddish brown powder; in- ties- soluble in water, but dissolving readily in hydrochloric (muriatic) acid. A very moderate heat drives off its oxygen and reduces it to the metallic state. It is composed of Gold 200 Oxygen 24 224—From these num- bers, it is evident that this oxide contains three times as much oxygen as the protoxide. Its medical 3. Peroxide of gold, as well as several other compoundi uses. 0f this metal, has been recommended by a French writer for the cure of the venereal disease. But it is believed that the subsequent trials of the preparations of the metal have not confirmed the reports made in its favour. Chloride of VII. Chloride of gold may be formed by heating the gold. metal, in a state of minute division, in chlorine gas. It is a brown substance. When exposed to the air, it decomposes moisture, and is converted into perhydrochlorate (permu- riate) of gold. VIII. Phosphuret of gold may be formed by fusing to- PLATINUM. 113 gether in a crucible one part of gold and two parts of dry Chap. hi. phosphoric acid, surrounded by charcoal. It i6 a very brittle substance of a much paler colour than gold. IX. Sulphuret of gold cannot be formed by fusing to- Sulphuret. gether its constituents; but if hydrosulpbate of potash or of soda be dropped into a solution of gold, this sulphuret falls in the form of a precipitate. It has a black colour. X. Gold combines with the majority of the other metals; Alloy of but the only combinations of this kind, which will be men- Sold ylh tioned here, are those with copper and mercury. silver^ ° 1. The alloy of gold and copper is easily formed by fu- forms gold sion. The copper increases the hardness, without injuring00"1 the colour of the gold. When gold is prepared for coining, it is alloyed either with this metal, with silver, or with a mixture of both. The gold, if coined perfectly pure, would be too soft for the purposes of money. The quantity of alloy- ing metal, which enters into the composition of the gold coin of the United States, Britain, France and Spain, may- be seen by the following table. Parts of pure gold, com- bined with oue part # of alloying metal. Gold coin of the United States contain . 11 -----------------Britain......11 •--------------France...... 9 nearly. -----------------Spain ...... 5'5 nearly. Goldsmiths, to express the purity of gold, suppose its alloys to be divided into 24 equal parts, which they call carats; and the pure gold is expressed in 24th parts. Thus gold said to be 20 carats fine, contains f^ths of pure gold and iVhs °f alloying metal. If gold is said to be 24 carats fine, it must be perfectly pure gold. 2. The amalgam of gold is used in some of the methods Amalgam of gilding. Silver, brass and copper may be gilded by it. ol g°\(iy The process consists in applying with a brush, a thin layer gHdin". of the amalgam, upon the metal to be gilded, and then ex- posing it to the heat of a charcoal fire. The mercury is in this way volatilized, and a thin layer of gold remains cover- ing the metal. SECTION XV. OF PLATINUM. I. Platinum may be obtained pure by the following pro- Platinum; cess: Dissolve the South American ore in aqua regia, and how ol»tain precipitate the solution by hydrochlorate of ammonia (salecl pure P 114 BASIFIABLE C0MBUST1BLKS b»ok I. ammoniac). Dissolve the precipitate in aqua regia also, and 1)ivision *• precipitate again by hydrochlorate of ammonia. The pro- duct of the second precipitation, when heated to whiteness, is pure platinum. Where II. Platinum has been found heretofore only in Spain; found. an(j jn three piaces in South America. Its localities in South America are, near Choco in Peru, at Santa Fe in New Granada, and in a district in the Brazils. It is usually al- loyed by a number of metals. Itsdiscore- HI. This metal, in its impure state, was first noticed in '.v 1741. Nothing, however, was ascertained of its propenies, until Dr. Lewis published his papers on it, in the Philoso- phical Transactions for 1754. Properties IV. Platinum is a white metal, possessing considerable of platinum brilliancy; but inferior in this respect to silver. Its hardness is intermediate between that of copper and iron. It is very ductile and malleable; possessing these qualities in a greater degree than any other metal, except gold. It is one of the most infusible metals. It is not in the slightest degree alter- ed by exposure to air or immersion in water. It is capable of being welded at a white heat. It may be made to burn by subjecting it to the intense heat, produced by the com- bustion of a stream of oxygen and hydrogen gases. Spec. grav. V. It is the heaviest body known, being about twenty- 21 *7- one and a half times as heavy as water. Platinum VI. Platinum combines in two proportions with oxygen, forms two anc[ forms protoxide and peroxide of platinum. OX IOCS l. Protox- 1- Protoxide of platinum may be obtained by dropping a •«'e- solution of mercury, into a dilute solution of hydrochlorate (muriate) of platinum in hot water. A powder precipitates, which is a mixture of protochloride of mercury (calomel) and this oxide of platinum. Expose this powder to a heat just sufficient to volatilize the protochloride; what remains will consist of the protoxide of platinum in a state of purity. It is in the form of a powder of a deep black colour. 2. Peroxide 2. Peroxide of platinum may be formed by decomposing sulphate of platinum, by pure potash added in excess. A precipitate appears, which must be heated to separate some water. It is then pure peroxide of platinum. Its colour is dark brown; when exposed to a high temperature it is re- duced to the metallic state. It dissolves in potash and soda, and in their carbonates. Platinum VII. Platinum combines in two proportions with chlorine, f°rTo9chio- an(* f°rms protochloride and perchloride of platinum. The ride and a protochloride is merely known to exist; its properties or composition have not been ascertained. The perchloride will be noticed in the following paragraphs. PLATINUM. 115 1. Perchloride of platinum may be formed by boiling the Chap. Ill metal in strong hydrochloric acid, adding occasionally a perchloX little nitric acid. The solution is to be evaporated to dryness, ride. and the dry mass digested in a little hydrochloric acid; which also is to be driven off. The dried residue is to be cautiously heated to redness, and afterwards boiled in a considerable quantity of water. Being separated and dried, it is pure perchloride of platinum. 2. This chloride has a dull olive brown colour. It is in- fusible and scarcely soluble. It is not altered by exposure to air. When exposed to a red heat, it exhales chlorine, and is reduced to the metallic state. VIII. Platinum combines in two proportions with phos- It forms a phorus, and forms protophosphuret and perphosphuret of platinum. 1. Protophosphuret of platinum may be obtained by heat- protophos- ing together phosphorus and platinum in an exhausted glass i'huiet,and tube. At a temperature below redness, they combine with a vivid ignition and flame. It has a bluish-grey colour, and is destitute of taste or smell. 2. Perphosphuret of platinum may be formed by heating perphos- hydrochlorate of platinum-and-ammonia, (ammonio-muriate phuret. of platinum), with two-thirds its weight of phosphorus, in a small retort over mercury. After the union has taken place, the whole must be exposed to a dull red heat to expel every thing volatile: what remains will consist of this perphos- phuret. It is a tasteless inodorous substance of an iron- grey colour. IX. Platinum appears capable of forming three sulphu- Platinum ^etS. forms three 1. Protosulphuret of platinum may be formed by heating su,Phurets- together equal weights of platinum "and sulphur, 'in an ex- hausted glass tube; and afterwards exposing the mass form- ed, nearly to a red heat, to drive off every thing vaporizable. It is a tasteless and inodorous substance of a dull bluish- grey colour. 2. Deutosulphuret of platinum may be obtained by pre- cipitating platinum from solution, by means of hydrosulphu- ric acid (sulphuretted hydrogen). The precipitate obtained must then be heated in a close vessel. It is a tasteless pow- der of a bluish black colour. 3. Persulphuret of platinum may be obtained by exposing a mixture of three parts of ammonio-hydrochlorate (ammo- nio-muriate) of platinum, and two parts of sulphur to a heat gradually increased to redness, and continued at that tem- perature, until every thing volatile is driven off. This sul- phuret has a dark iron-grey colour. It is not fusible when 116 Book I. Division I. Alloys of platinum. Platinum as a medi- cine. BASIFIABLE COMBUSTIBLES. exposed to a considerable heat in close vessels; but when subjected to a red heat in the open air, it is decomposed; the sulphur is dissipated, and the platinum is left behind in the metallic state. X. The alloys of platinum have not as yet been applied to any useful purposc, if that with copper be excepted. This alloy has been employed, with advantage, for forming the mirrors of reflecting telescopes. Platinum itself may be considered useful in every case, in which hard and indes- tructible metallic substance is required. XI. Platinum, in solution in aqua regia and combined with soda, has been empoyed, with seeming advantage, in some cases of syphilis. SECTION XVI. OF PALLADIUM. Palladium; how obtain- ed p'u«. Found in ende pla- tina. Its proper- ties. I. Palladium may be obtained pure by dissolving crude piatina from South America in aqua regia, and pre- cipitating the solution, by means of a solution ol cyanodide (prussiate) of mercury. The precipitate thus obtained, after being washed, dried and exposed to a strong heat, is con- verted into pure palladium. II. Palladium is one of the peculiar metals, which have been detected in the crude piatina of South America. It was discovered in 1803 by Dr. Wollaston. III. Palladium is white, and susceptible of being polish- ed. It is somewhat harder than wrought iron. It possesses some malleability. It undergoes no alteration in the air. It is extremely infusible: in the highest heats that can be rais- ed, it fuses only in minute portions. When fused on char- coal by means of a jet of oxygen, it was made to boil, and at last to undergo combustion; emitting at the same time brilliant sparks. IV. It is about eleven and a half times as heavy as water. V. Palladium combines with oxygen in one proportion only, and forms oxide of palladium. It may be obtained by heating palladium filings with pure potash, mixed with a little nitrate of potash (nitre). It has a chesnut-brown co- lour. It is composed of Palladium 56 Oxygen 8 64 Chloride of VI. Chloride of palladium may be formed by the agency palladium. 0f heat. Its properties have not been examined. Spec. grav. 11-55. Formb hut one oxide. RHODIUM. 117 VII. Sulphuret of palladium may be formed by throwing Csxat.iii. sulphur upon strongly heated palladium. The metal imme- Sulphuret. diately enters into a state of fusion, and the union takes place. It is very brittle, and rather paler than palladium. SECTION XVII. OF RHODIUM.* I. Rhodium may be obtained by the following process: Rhodium; Subject crude piatina to the action of aqua regia, as long as JjJ pur?™" this menstruum dissolves any thing. Separate the black powder, which will be found to have resisted the action of the aqua regia; and to the clear solution, add a solution of hydrochlorate of ammonia (sal ammoniac): this addition will throw down nearly all the platinum. After separating this precipitate, immerse, into the clear solution, a rod of zim : this metal throws down rhodium, confeminated with copper, lead, platinum ann palladium, in the form of a black powder. Bv submitting this powder to the action of diluted nitric acid, the copper and lead will be dissolved; while the other inv-uls, which it contains, will remain untouched. What is left after the at tion of the nitric acid is then dis- solved in aqua regia, and chloride of sodium (common salt) aucL-d to the solution. The whole is then evaporated to dry- ntss; and the mass obtained will consist of the oxides of rhodium, platinum and palladium in combination with the chloride of sodium. The oxides of platinum and palladium, in this state of combination, are soluble in alcohol; whereas the oxide of rhodium is insoluble. By washing the mass, therefore, repeatedly in alcohol, the oxides of platinum and palladium are removed; so that nothing remains but oxide of rhodium in combination with chloride of sodium. Dis- solve this residual compound in water, and place in the solution a rod of zinc: this metal throws down the rhodium in the form of a black powder, which may be fused into a mass along with borax. II. Rhodium has been found only in the crude piatina Found only from South America. It was discovered by Dr. Wollaston "'crude in 1804. plat,na- III. Rhodium is a brittle metal of a white colour; and, its proper- excepting perhaps iridium, next to be described, the mostties* infusible of the metals. It has the distinguishing property of being insoluble in all the acids. • From fif,o(, rose-coloured, on account of tht red eolonr of dilute solutions of the salts of this metal. 118 BASIFIABLE COMBUSTIBLES. Book I. IV. It is somewhat more than ten and a half times as DWisfonL^ heavy as water. Spec. m-av. V. Rhodium combines in three proportions with oxygen. Fw'649' I* Protoxide of rhodium may be obtained by exposing three* ox- rhodium in powder, in an open vessel, to a moderate red Ides. heat. It is a black substance, which is insoluble in acids. When heated with tallow, it deoxidizes with detonation. It is doubtful whether this oxide enters into the composition of any salt. 2. Deutoxide of rhodium may be formed by heating the metal, in powder, with a mixture of potash and nitrate of potash (nitre), and exposing the resulting mass to the action of sulphuric acid. This acid dissolves off the potash; and what remains consists of the oxide in question. It has a brown colour. It does not enjoy the property of a salifiable base. 3. Peroxide of rhodium may be prepared by precipitating the compound*)! oxide of rhodium and chloride of sodium (soda-muriate of rhodium), by potash, and exposing the precipitate obtained to heat. It has a red colour. It is this oxide which is present in the salts of oxidized rhodium. SECTION XVIII. OF IRIDIUM.* Iridium; I. Iridium may be obtained pure by the following pro- how obtain- CCss: Expose the black powder, which remains undissolved by the action of aqua regia upon crude piatina, mixed with five times its weight of pure soda, in a silver crucible, to a red heat for half an hour. Subject the resulting mass to the action of water, in order to dissolve off the soda. Treat the residue alternately with hydrochloric (muriatic) acid and potash, until it becomes totally dissolved: by the action of the potash a peculiar metal is separated, which will be described in the next section; that part of the residue, how- ever, which dissolves in the hydrochloric acid, consists of iridium. Evaporate the acid solution to dryness; and, in order to get rid of some osmium, dissolve the dry mass in hydrochloric acid, and evaporate the solution until it crys- tallize. The crystals, thus obtained, will consist of hydro- chlorate (muriate) of iridium. Expose them to a high * From iris, the rainbow; on account of the remarkable variety of colours which this metal exhibits in solutions. OSMIUM. 119 temperature in a platinum crucible; the acid, and the oxygen Chap. in. of the oxide are driven off; so that nothing will remain but pure iridium. II. Iridium was discovered in 1803, about the same Found only time, by Tennant and Descotils. It exists only in the crude "j T1(le piatina of South America. III. Iridium is a brittle metal of a white colour. It isluproper- the most infusible metal known. It resists the action of alltie8- solvents except aqua regia; and this last makes but a slight impression upon it. IV. At a mean, it is about nineteen times as heavy as Spec. gray. water. 1896- V. Judging from the phenomena, which attend the solu- Supposed tion of iridium in hydrochloric (muriatic) acid, it would oxides? tW° appear that this metal is capable of forming two oxides; but nothing is known of their individual properties. SECTION XIX. OF OSMIUM.* I. OsMiuft may be obtained by the following process: Osmium; Distil the black powder obtained from crude piatina, mixed h?w obtaifl" with nitrate of potash (nitre), at a low red heat: the potash e PUr of the nitrate combines with the osmium present in the black powder; and, from this combination, allows it to sublime in the state of oxide. Dissolve the oxide thus obtained in water, and agitate the solution along with mer- cury: the oxide becomes reduced to the metallic state, and forms a combination with mercury. By distilling this amal- gam, the mercury is driven off in the state of vapour, while the pure osmium remains behind. II. Osmium was discovered by Tennant in 1804. Like Found only the two metals last described, it has been found only in the in crude crude piatina from South America. pi»una. III. Osmium has a dark-blue colour, and the metallic Its proper- lustre. When exposed, in close vessels, to a white heat, itUes- does not melt or undergo any change; but, when heated in the open air, it becomes oxidized, and evaporates with a peculiar smell, resembling that of chlorine. After being ex- posed to heat, it is not acted upon by any acid. Its weight, compared with that cf water, has not been ascertained. • From ; C> Q D C a- o p 3 ^mSlmes.^"^- ' 1. Carbon. 2. Boron. 3. Phosphorus. 4. Sulphur. 5. Arsenic. 6. Chromium. 7. Molybdenum. 8. Tungsten. 9. Columbium. JO. Selenium. II. Acidifiable combustibles. III. Intermediate C 1. Antimony. combustibles. \ 2. Tellurium. III. Combustibles.^ IV. Basifiable combustibles. f 11. Potassium. a. Basifiable combustibles, J 3* uUniitn forming, with oxygen, alv ± Calcium. kaline salifiable bases; or, j s Barium alkalifiable combustibles. 6'. Strontiilm. ^ 7. Magnesium. f 1. Yttrium. , „ ., ,, , .... ! 2. Glucinum. b Basifiable combustibles,! 3 A,Qminum. forming, with oxygen,^ 4 zirconium. earthy salifiable bases. 5. Thorinum. v. 6. Silicum. c. Basifiable combustibles, forming, with oxygeu, sa- lifiable bases, having nei-< ther alkaline nor earthy properties. r 1. Iron. 2. Nickel. S. Cobalt. 4. Manganese. 5. Cerium. 6. Uranium. 7. Zinc. 8. Lead. 9. Tin. 10. Copper. 11. Bismuth. 12. Mercury. 13. Silver. 14. Gold. 15. Platinum. 16. Palladium. 17. Rhodium. 18. Iridium. 19. Osmium. 1.20. Titanium. ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. J25 Chap. IV. CHAPTER IV. ACCOUNT OF THE ARRANGEMENT OF THE UNDECOMPOUNDED PONDERABLE BODIES. The arrangement of these bodies, as seen by the table, Arrange- is in many respects different from that adopted by Dr. ment of un- Thomson;'although founded on the classification of thisJSSSrf author. The work of Dr. Thomson has been constantly ponderable before me; and I do not know whether the same arrange- ££{&, up. ment would have occurred to me, if I had never seen his on that pmy system. Be that as it may, the truth is, I never hesitated to ?,u*d bv Dr- alter his arrangement; when, upon careful consideration, a conviction was felt," that the alteration would tend to sim- plification and precision. In short, I never altered, merely for the sake of altering; neither did I, in any case, give up my mature judgment, merely because it differed from that of a chemist of high authority. In as concise a way as possible, I shall take notice of the alterations which have been made in Dr. Thomson's arrange- ment; and afterwards mention what appear to be the prin- cipal defects of the classification, as it stands in the present work. The arrangement adopted, in its primary divisions, agrees It agrees with that of Dr. Thomson: the undecompounded pondera- *"h Dr#, , , . ,. i • • i i • c i ■ * homson's, ble bodies are divided into supporters of combustion, in- initsprima- combustibles, and combustibles, ry divisions. Dr. Thomson divides the combustibles into three genera, Dr. Thom- w hich he defines in the following words. SOn divi.des " I. Bodies forming acids by uniting with the supporters Wes into' of combustion or with hydrogen." thlee ge- " II. Bodies forming alkalies or bases, capable of consti-nera" tuting neutral salts with acids, by uniting with the suppor- ters of combustion."* 44 III. Bodies producing by their union with the suppor- ters of combustion, imperfect acids, or substances interme- diate between acids and alkalies."! As introductory to the account of the third genus, Dr. Thomson gives the following distinguishing characters to the bodies included under that head. 44 The substances belonging to this genus may be consi- dered as intermediate between the first and the second • Thomson's Chemistry, vol. I. p. 220. f.lbid. P- 221.—Ed. 1817. 126 ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. Book I. Division I. What bo- dies Dr. Thomson includes under his first genus; what, un- der his se- cond genus and what, under his third Arrange- ment adopt ed has a set of acidi fiabie com bustibles; which con- stitute the second class. genus. They differ from those of the second genus, by forming compounds with oxygen, which do not neutralize acids; and from those of the first genus, by not entering into any gaseous combinations. They agree with the bodies of the first genus; because their oxides possess acid proper- ties. They agree with the bodies of the second genus; be- cause these acids are but imperfectly soluble in water, and act with but little energy upon animal and vegetable bodies."* Under his first genus, Dr. Thomson gives hydrogen, carbon, boron, silicum, phosphorus, sulphur, arsenic, and tellurium; to which he adds osmium from analogy. Under the second genus, he includes the following bodies, divided into five families. 1st Family; Potassium, sodium, calcium, barium, strontium, magnesium. 2d Family; Yt- trium, glucinum, aluminum, zirconium, thorinum. 3d Fa- mily; Iron, nickel, cobalt, manganese, cerium, uranium. 4th Family; Zinc, lead, tin, copper, bismuth, mercury, silver. 5th Family; Gold, platinum, palladium, rhodium, iridium. Under the third genus, he gives antimony, chromium, molybdenum, tungsten, columbium, titanium. In my arrangement of the combustibles, I have a class of ' acidifiable combustibles. But the definition of it is differ- . ent from that, given to the corresponding class by Dr. Thom- son, as may be seen by the table. It includes such com- bustibles as form acids, and in no case salifiable bases, by uniting with oxygen. Hydrogen, therefore, is excluded from it, as this combustible forms no acid with oxygen; and is erected into a separate class, for reasons which will be given presently. Silicum is excluded also; because the proofs of its oxide (silica) being an acid are not satisfactory. Tellu- rium is excluded; because it forms a compound with oxy- gen, which performs the part of a base, as well as of an acid. The definition, however, while it excludes some bodies of Dr. Thomson's genus, embraces others, not included in his. Thus chromium, molybdenum, tungsten and columbium are brought in here, from Dr. Thomson's third genus, where they are called bodies capable of forming with oxygen im- perfect acids; because they form acids with oxygen, but never salifiable bases.f The acidifiable combustibles, as just enumerated, form the second class of combustibles in the table. The first con- tains one body only, and that is hydrogen. * Thomson's Chemistry, vol. I. p. 528. t Selenium has been classed with the acidifiable combustibles, since the above tvis written ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. 127 There are a number of acids, which agree, as to constitu- Chap. iv. tion, in no other particular than in containing hydrogen. These The first are hydrochloric (muriatic) acid, hydriodic acid, hydrosul- c|?«s con- phunc acid (sulphuretted hydrogen), hydroselenic acid JJJJj^JjJjf!*" (selenuretted hydrogen), hydrotelluric acid (telluretted hy- drogen), hydrofluoric (fluoric) acid, and hydrocyanic (prus- sic) acid. It is for this reason that I have put hydrogen in a class by itself, and ventured to call it an acidifying body. The term acidifying is not meant to convey the idea of any which is exclusive agency of the hydrogen in the production of the ca!le^ an acid properties, in the particular acids above mentioned; but combust^ it is used as being convenient, and best suited to express ble- the idea. It is, certainly, equally admissible with the term acidifiable; since an active participle may be used with the same propriety as the passive potential. Besides, hydrogen does not stand well along side of the Arrange- bodies, with which Dr. Thomson has associated it in his mc".tinthis first genus. Excepting hydrogen, all the bodies of this ge-jEfied^ nus form acids with oxygen, (assuming Dr. Thomson's opinion respecting silicum), and agree very well in this par- ticular. Hydrogen, however, forms no acid with oxygen; while with sulphur, one of the substances, also included in the genus, it forms a compound having acid properties. The title of my third class is adopted from Dr. Thomson; Title of but by intermediate combustibles, I do not mean the samethird class thing with this author. He understands by intermediate SbKJbS." combustibles, such bodies as form 44 by their union with the rowed fr0«» supporters of combustion, imperfect acids, or substances £n.UuJe intermediate between acids and alkalies." Under the accep- term inter. tation in which the term is here taken, it designates those r^di?te ta" combustibles, which, by union with oxygen, form com- new uwp. pounds, which act the part of acids and of bases, in differ-tation- ent cases of combination. Hence the reason that chromium, molybdenum, tungsten, and columbium are carried into the second class in this work; since the oxides of these bodies, which enter into the constitution of salts, always take the part of acids, and in no case of salifiable bases. Titanium also is excluded from the class of intermediate combusti- bles, where Dr. Thomson has placed it; as not answering to the meaning of the term, as here adopted. It does not, in fact, answer to its meaning, as explained by Dr. Thom- son himself; who nowhere, in his work, ascribes, to its compounds with supporters, acid properties of any kind; or any other properties, which would justify the belief, that they are substances intermediate between acids and alkalies. Under the particular acceptation, in which the title inter- mediate combustibles is here taken; I retain but one body 128 ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. Book i. placed under this head by Dr. Thomson; and that is and- Division I. mony. it is because this metal forms compounds with oxy- gen, one of which performs the part of a salifiable base; while the others (antimonious and antimonic acids) perform the part of acids. Tellurium, which was excluded from Dr. Thom- son's genus of acidifiable combustibles, is inserted here; be- cause the only compound which it forms with oxygen is sometimes an acid and sometimes a salifiable base. The reader, however, will observe this difference between anti- mony and tellurium; that while the respective offices of acid and of base are performed by different oxides of anti- mony; both these offices belong to the only oxide, which tellurium is capable of forming. Two bodies Thus it is perceived that the class of intermediate com- ed'under"1" bustibles is made to embrace but two bodies; antimony and the title of tellurium. It is placed next to the class of acidifiable com- interme- bustibles; in order that the bodies, which it embraces, may bustibles. stand as close as possible to the acidifiable metals, to which they bear a very close analogy. Combusti- My fourth class is called by the'title of basifiable com' bies em- bustibles. It corresponds exactly with Dr. Thomson's braced un- . c r ,._■'... in der the second genus, as tar as the definition is concerned. Hut fourth class besides the bodies included under it by this chemist; I liable. 3Sl have added silicum, to which its old position is given; osmium, because the force of analogy is not sufficiently strong to justify its position among the acidifiable combus- tibles; and titanium, for the reasons which excluded it from the class of intermediate combustibles. I do not retain the families into which Dr. Thomson has divided this class; because they have no well marked This class characters, except the first and second. The class is divided, divided into jn the present work, into three sub-classes: the first sub-class classes. embraces alkalifiable combustibles;* the second, combusti- bles forming earthy salifiable bases; and the third, combus- tibles forming salifiable bases, having neither alkaline nor earthy properties. Thus I have given the reasons, which induced me to modify Dr. Thomson's arrangement of the undecompounded ponderable bodies. Indeed, I have taken so many liberties with it, as to change almost entirely its aspect; and, while the arrangement of the present work bears resemblance to it, in some respects; in otheTS, it is totally different. It ii confessedly founded upon the arrangement of Dr. Thorn- * This sub-class contains lithium, in addition to-the bodies included under it bf Dr. Thomson. Lithium was not known when the last edition of this chemist' work was put to press. ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. 129 son; and when I first undertook to prepare this volume, Chap.IV. from materials, drawn, principally, from his copious work, "~ I had not conceived the design of altering it. But in my progress there appeared to be several alterations which could be made witb advantage. These, however, were not made hastily; for I gave every point very scrupulous atten- tion, in order to see whether further investigation would destroy my first impressions; and, not till after I was unable to convince myself that I was wrong, did I adopt the mo- difications. I should not have employed so much time in giving the preceding account of the arrangement, which I have adopt- ed; but that I have attempted to substitute something, in many respects my own, for what has received the approba- tion of a respectable portion of the chemists of the day. Unknown as I am in chemistry, my suggestions in the scientific arrangement of its objects can have no weight of authority; but must stand upon their intrinsic merits, and depend, for their adoption, upon the exhibition of satisfac- tory reasons. After all the attention I have bestowed upon the Prominent arrangement of chemical bodies, I freely acknowledge, that,defects of in several respects, the one which is adopted is far from rangement being satisfactory. In the first place, it is not probable that »s adopted. the phenomena, attendant on combustion, will long continue to afford a convenient basis, upon which to erect the primary divisions of chemical bodies. Already is the class of sup- porters swelled to four by the addition of bodies, which do not stand well associated with oxygen; and yet it does not contain all the bodies which legitimately belong to it. Potassium, sulphur and phosphorus are as fully entitled to be called supporters as iodine or fluorine; because, in some of their combinations with bodies not supporters, the chemical action is so intense as to produce both sensible light and heat. Thus it is perceived, that, under the definition of a supporter, bodies, in many respects dissimilar, would be unnaturally grouped together, and the end of scientific ar- rangement thereby defeated. Again, all the substances, which are arranged under the title of combustibles, forming salifiable bases, with oxygen, having neither alkaline nor earthy properties, in strict pro- priety do not belong here. Without doubt, the oxides of cerium, of uranium, of titanium, and of some other metals arranged here, are as perfect earths as yttria, glucina, or any of the other bodies, which have generally been de- nominated earths. Hence there is no reason why these R 130 ARRANGEMENT OF THE UNDECOMPOUNDED BODIES. (Book I. metals should not be classed along with the basifiable com- Divigion '• bustibles, forming earthy bases with oxygen. Having thus finished the account of the arrangement of the undecompounded ponderable bodies, pursued in this work; it may not be without its use to recapitulate, in tables, their more important properties. Table of the Supporters of Combustion, Incombustibles, and the Acidifying Combustibles. Names of the Bodies. Discoverers, and thin- of discover). Synonymes. State as to ag-gregation at the common temperature of the air. Colour. Smell. Taste. Quantity solu-' ble in 100 cu-1 bic inches of water; in cu-. bic inches. Specific Gravity. i ™™' Compared with Compared wiih air as unity. water as uiu- combustion. : spiration. i 1. Oxygen. Priestley; 1774. Depblogisticat-ed air; vital air. Gaseous. Colourless. Inodorous. Insipid. 1-108. Supporter. Respirable. 2. Chlorine. Discovered by Scheie; 1774. True nature made out by Davy and (jay-Lusiac. Diphlogisticat-ed muriatic acid; uxymuri-atic acid. Gaseous. Greenish-yel-low. Strong and suf-focating. 200-00. 2-4700. Supporter. Unrespirable; noxious. 3. Iodine. Courtois; 1811. Solid. As a solid, greyish-black. As vapour, violet. Similar to, but not so strong as that of chlo-rine. Acrid and hot. Very sparingly soluble. As vapour, 8-678. As a solid, 4-948. Supporter. 4. Fluorine. Existence made probable by Davy; 1810. Probably solid. White, in com-bination with Potassium.* 5. Azote. Rutherford; 1772. Phlogisticated air; nitrogen gas. Gaseous. Colourless. Inodorous. Insipid. 1-47. 0-978. Incombustible. Respirable; but not capable uf supporting life. 6. Hydrogen. Cavendish; 1766. Light inflam-mable air. Gaseous. Colourless. Inodorous. Insipid. 1-S3. 0-0732. Combustible. Respirable; but not capable of supporting life. * Nothing more is known of this substance; it never having been obtained in a separate state. Table of the Acidifiable Combustibles. Names of the Bodies.* Discoverers, and time of discovery. Synonymes. Whether me-tallic. Colour. Smell. Taste. Specific Gra-vity compared with water as unity. Melting Point. Point of vapo- Acids formed, of which each body is the base. Fahrenheit. Wedgewood. rization, or vo-latilization. 1. Carbon. Charcoal. Non-metallic. Black. Inodorous. Insipid. 0-441. Infusible. Carbonic acid. 2. Boron. Gay-Lussac and Thenard; 1808. Non-metallic Brownish-green. Inodorous. Insipid. After exposure to beat; 1-844 + Infusible. (,.; Not volatiliza-ble. Boracic acid. 3. Phosphorus. Brandt, a Ham-burgh chemist, 1669. Non-metallic. White, when pure. Bright amber, as usually ob-tained. 1-770. 108° 219° Hypophospho-rous acid. Phosphorous acid. Phospho-ric acid. 4. Sulphur. Known from the earliest ages. Brimstone. Non-metallic. Greenish-yel-low. Inodorous. Perceptible, but weak. 1-990. 218" 170« Hyposulphu-rous avid. Sul-phurous acid. Sulphuric acid. Hydro>tilphu-rous acid. Hy-drosulphurie acid. 5. Arsenic Unknown. Metallic. Bluish-white. Inodorous when cold; but smelling like garlic when heated. 8-31. Unknown. 356° Arsenious acid. Arsenic acid. 6. Chromium. Vauquelin; 1797. Metallic. Between that of tin and steel. S-90. §170"+ Chromic acid. • All tlu- bodie. described in thi» table are aalida, at the common temperature of the air. i IW lx i;viu»in« of Wndfuewd1. Mate imilMlliUMl. with «►«• of F^ma»hcit'i, or a red beat; and every degree of it U e<|ual to ISO* of the latter. Table of the Acidifiable Combustibles (continued) and of Intermediate Combustibles. Discoverers, and time of discovery. Synonymes. Whether me-tallic. Colour. SmelL Taste Specific Gra-vity compared with water as unity. Melting "oint. I Point of vapo- Aculs form d. »f which each Names of the Bodies.* Fahrenheit. Wedgewood. nwjt-on or vo- b ^ a lhe Utilization. ; tasJ 1 7. Molybdenum. Bergman and Hjelm: 1782. Metallic. Silver-white. Hjelm, 7-400. Bucholz, 8-611. 170" + Molybdous acid. Molybdic acid. 8. Tungsten. Messrs. D'El-huyarts: 1782. Wolframium. Scheelium. Metallic Greyish-wbite. 17-4. 170° + Tungstic acid. y. Columbium. Hatchett and Ekeberg: 1801. Tantalum. Metallic. Dark-grey. 5-61 170° + Coluinbic acid. 10. Selenium. Berzelius: 1818. Intermediate between metal-lic and non-me-tallic bodies. Slightly red. During com-bustion, like that of horse radish. 4-6. Somewhat higher than that of boiling water. Selenic acid. Hydroselenic acid. 1. Antimony. Basil Valen-tine: end of 15th century. Metallic Greyish-white. Peculiar. Peculiar. 6-712. 947° Antimonious acid. Antimonic acid. 2. Tellurium. Klaproth: 1798. Metallic. Bluish-white. 6-115. 612« + 612° + Telluric acid. Hydrotelluric acid. • All the bodiei deicribed in this Table are solids, at the common temperature of the air. Table of the Basifiable Combustibles. Names of the Bodies. Discoverers, and time of disco-very. State as to aggre-gation, at the common t?m-perature of the air. Colour. Smell. Taste. Specific Gravity. compared with w«ter as unity. Melting i-'ahreuhtit. Point V\ edgewood. 1. Potassium. Davy; 1807. Solid. White. 0 865. 136-5° 2. Sodium. Daw; 1808. Solid. White; between that ot" silver and lead. 0972. 194° 3 Lithium. Davy; ,1818. Solid. White. 4. Calcium. Berzelius & Pou-tin, and Davy; 1808. Solid. Resembling that of silver. 5. Barium. Berzelius and Pontin; 1808. Solid. Resembling that of silver. Four or five times as heavy as wa-ter. Under a red beat. 6. Strontium. Davy; 1808. Solid. White. 7. Magnesium. Davy; 1808. Solid. White. | Table of the Basifiable Combustibles,—Continued. Names of the Bodies. Discoverers, and time of disco-very. State as to aggre-gation, at the common tem-perature of the air. Colour. Smell. Taste. Specific Gravity, compared with water as unity. Melting Point. Fahrenheit. Wedgewood. 8 Yttrium. Davy; 1808. Solid. 9. Glucinum. Davy; 1808. Solid. Dark. 10. Aluminum. Davy; 1808. Solid. 11. Zirconium. Davy; 1808. Solid. 12. Thorinum. Existence render-ed probable by Berzelius; 1815. Berzelius and 13. Silicum. Davy; 1808. Solid. Dark. 14. Iron. Known from the earliest ages. Solid. Bluish-white. Peculiar, v.lien rubbed. Styptic. From 7-6 to78. 158°. Table of the Basifiable Combustibles,—Continued. Names of the Bodies. Discoverers, and time of discove-ry. State as to aggre-gation, at the common tem-perature of the air. Colour. Smell. Taste. Specific Gravity,! compared with water as unity. Melting Point. Fahreniieit. Wedgewood. 15. Nickel. Cronstedt; 1751. Solid. White. 8-402. 160«. 16. Cobalt. Brandt; 1733. Solid. Grey, with a tint of red. Scarcely any. Scarcely any. 8-53. 130". 17. Manganese. Kaim and Gahn; between 1770 & 1775. Solid. Greyish-white, Like that of cast-iron Inodorous. Insipid. 8013. 160o. 18. Cerium. Berzelius & Davy; between 1804 k 1807. Solid. Deep-grey. Difficultly fusible. 19. Uranium. Klaproth; 17S9. Solid. Iron-grey. 8-100. 170-. 20. Zinc. Unknown. Solid. White, with a shade of blue. Perceptible. Peculiar. 6 861. 680°. 21. Lead. Known from the earliest ages. Solid. Bluish-white. Peculiar, when rubbed. Perceptible. 11-352. 1 612«. Table of the Basifiable Combustibles,—Continued. Naii- s of the Bodies. Discoverers, and time of disco-very. Slate as to aggre-gation, at the common tera-perature of the air. Colour. Smell. Taste. Specific Gravity, compared with water as unity. Melting Point. 1 /----------A----------A Fahrenheit. Wedgewood j 22 Tin. Kn'-un from the earliest ages. Solid. White, like that of silver. Peculiar when rubbed. Slighti v disagree-able. 7291. 442°. 2.S. Copper. Known from the earliest ages. Solid. Red. Peculiar and dis-agreeable. Styptic and nau-seous. 8-895. 27°. 24. Bismuth. Not kniwn in p. pure state before the inidiileof the 18th century. Solid. While, with a tint of red. Inodorous. Insipid. 9822. 476°. 25 Mcrcuiy. Known from tht earliest ages. Liquid. White, like that of sil vet. Inodorous. Insipid. 13 568. —39°. i 26. Silver. Known from the earliest ages. Solid. Brilliant white, with a shade of yellow. Inodorous. Insipid. 10-474. 22°. 97 Gold. Jnown from the earliest ages. Solid. Pine light yellow. Inodorous, Insipid. 193. 32°. Table of the Basifiable Combustibles,—Concluded. 1 Names of the Bodies. Discoverers, and time of disco-very. State :;s to aggre-gation, at the common tem-perature of the air. 1 ————— Taste. Specific Gravity, compared with water as unity. Melting Point. I Colour. Smell. Fahrenheit. Wedgewood.1 28. Platinum. Lewis; 1754. Solid. White, but less brilliant than that of silver. Inodorous. Insipid. 21-47. 170° + 29. Palladium. Wollaston; 1803. Solid. White. At a medium, 11-55. 170° + 30. Rhodium. Wollaston; 1804. Solid. White. 10-649. 180° + 31. Iridium. Tennant and Descotils; 1803. Solid. White. At a mean, 18 96. , 180"+ 1 S2. Osmium. Tennant; 1804 Solid. Dark-blue. Odorous, when heated. Very i ifusible. 33. Titanium. 'Vauquelin and Hecht; 1796. Solid. Like that of copper. 170» + ACCOUNT OF THE ATOMIC THEORY. 139 Chap. V. TABLE Of the Specific Gravities, as far as they are known, of the Undecompounded Ponderable Bodies, given in the order of their relative amounts. Compared with air as unity. Compared-with -water as a unity. 1. Hydrogen 0*0732 20. Zinc 6 861 2. Azote 0978 21. Tin 7-291 .1. Oxygen 1 108 22. Iron 7-7 medium. 4. Chlorine 2-4700 23. Manganese 8013 Compared -with ■water as unity. 24. Uranium 8100 5. Potassium 0865 25. Arsenic 831 6. Sodium 0-972 26 Nickel 8-402 7. Magnesium 1 + 27. Cobalt 8-53 8. Phosphorus 1-770 28. Molybdenum 8-611 Bucholz. 9. Boron 1-844 29. Copper 8895 10. Sulphur 1-990 30. Bismuth 9822 11. Carbon $ charcoal 0-441 (diamond 3*5 31. Silver 32. Rhodium 10474 10649 12. Barium 4 5 estimated. 33. Lead 11-352 13. Strontium 45 estimated. 34. Palladium 11-55 medium. 14. Selenium 4-6 35. Mrcury 13-568 15. Iodine 4948 36. Tungsten 17-4 16 Columbium 5-61 37. Iridium 18 96 medium. 17 Chromium 5-90 1 38. Gold 19-3 18. Tellurium 6 115 39. Platinum 21-47 19. Antimony 6712 1 The undecompounded bodies, whose specific gravities have not as yet been ascertained, are fluorine, lithium, calcium, yttrium, glucinum, aluminum, zirconium, thori- num, silicum, cerium, osmium, and titanium. CHAPTER V. SKETCH OF THE ATOMIC THEORY OF CHEMICAL COMBINATION. At this stage in the progress of the present work, it ap- Object of pears to be most expedient to introduce to the notice ofthis chaP- the reader, the leading facts known respecting the propor- ter stated' tions and the manner in which bodies unite chemically. For the purpose of illustration, a set of bodies will be selected; and the quantities in which each of them combines with oxygen and hydrogen, both taken at unity, will be noted. 140 ACCOUNT OF THE ATOMIC THEORY. Bo ok I One part of C 4-5 parts of chlorine, forming protoxide of chlorine. Division I. Oxygen 1 -75-------carbon, -------carbonic oxide. ---------- combines J 1 5 ------phosphorus,-------phosphorous acid. Statement witn V. 2- ------sulphur, —— hyposulphurous acid. of chemical propor- One part of C 45 +8 or 36 parts of chlorine, forming hydrochlorio acid. tions. Hydrogen J 75+ 8 or 6------- carbon ----hydroguret of carbon. combines | 1*5 HorU ——-— phosphorus —— hydroguret of phoaphonu. with I. 2 +8 or 16 ------ sulphur ----hydrosulphuric acid. Deduction From the above statement, it must be evident, that what- from this ever quantity of chlorine, carbon, phosphorus or sulphur statement; ,? X, . ' . r • l • T,,u,» combines with a given quantity of oxygen; eight times such quantity unites with the same amount of hydrogen. which is on- The proposition, however, as just stated, is only true of der certain ^e c°mP°unds spoken of, when their constituents combine circumstan-in the simplest proportions. But when one body combines ce8, with another in more than one simple proportion; even- new proportion is some multiple of the first. Proposition Now, the proposition just made, with respect to oxygei fomTtate- anc* hydrogen, -s not on-y true w^h regard to their combine ment given, tions with chlorine, carbon, phosphorus and sulphur; but also universally Wlth regard to those compounds, which they form with all bodies unite other substances; at least as far as such compounds have in the sim- been carefully investigated. So that it may be stated as uni- portLm™ Versal-V true, that the quantities in which bodies combine, chemically, with any one body, in the simplest proportion, are invariably proportional to the quantities in which the same bodies combine with any other body. Proposition It is further found, that when two bodit-s, a and b, combine extended; with a th-ird c; by whatever multiple the quantity in which c combines with b, exceeds the quantity in which c com- bines with a; then, in the combination of a and b, by the same multiple will the quantity a exceed the quantity*. illustrated For example: both oxygen and hydrogen combine with chlo- ampTe."" rine> x Part of oxygen with 4*5 of chlorine; 1 part of hy- drogen with 36 of chlorine. Now 36 is 8 times 4*5; there- fore the quantity in which chlorine combines with hydro- gen, exceeds that in which it combines with oxygen, by the multiple 8. But one part of oxygen combines with the eighth part of one of hydrogen or 0*125; therefore by the same multiple, by which the quantity of chlorine combining with hydrogen, exceeds the quantity of the same body uniting The composition of all the«hemical compounds, which are se lee ted, for the purpose of illustration in this chapter, «ill not be found in the preceding part* 2wJ? ."I,"16' ltfWOuU,(!„not b? ea8> t0 Pve eve" « toler,bly clear aceountaf tbl d&b2eT& a ,n.ustrat,onf8 *«* •»«"*> only from tne compounds slmdj Sons wkh whfnheK « 'V Vheref°;'C' re1ue?te(l t« take for granted the «»[»* SpSd ^^t^ic^ir^ac,i,,ainted'and which are °°* ACCOUNT OP THE ATOMIC THEORY. ± 4 j[ with oxygen; does the quantity of oxygen exceed the quan- Chap. V. tity of hydrogen in the combination of oxygen and hy-""" drogcn. Now the reader will bear in mind, that what is here said of oxygen, hydrogen, and chlorine, applies to all other bodies, whose coqiibinations have been accurately ascer- tained. If the question be asked, why hydrogen combines with 8 times as much of any body as ox> gen does; the probable explanation may occur to the reader, if he advert to the fact, that, in the compound formed by these two bodies, the hydrogen constitutes £th only of the amount of the oxygen; and he may say, that as the hydrogen is assumed as one, which is 8 times greater than its proportional equivalent, compared with that of oxygen taken at unity also; then in that relative amount, it combines with 8 times as much of another body as oxygen does. But if taken at its simple equivalent, which is one-eighth of 1, or 0*125; then that quantity of hydrogen combines exactly with the same quan- tity of any other body, as 1 of oxygen does: or, to express the same thing without a decimal, 1 part of hydrogen com- bines with the same quantity of any other body, as 8 parts of oxygen do. The law of combination, last stated, holds good with re- gard to all compounds, whose constituents unite in simple proportions. So that if the chemist should find that the sim- plest combination of hydrogen and sulphur contained 1 part of the former and 16 of the latter; he would be able to infer, that the same quantity of any body, which combines, simply, with 1 part of hydrogen, will unite, in the same manner, with 16 parts of sulphur. The reader has now been made acquainted with several re- The lead- markable coincidences in the proportional numbers, in which ins proposi- chemical bodies combine: it is natural for him to inquire, ;ng t0 defi- upon what peculiarities in the manner of their combination ""e chemi- do these depend? fij^ The explanation of this point cannot be made to rest now stated; upon absolute proof; but upon a train of reasonings so ex-and act in all its parts, as to make it almost universally ad- mitted. If it be supposed, that, when two bodies unite chemically, it is either a union of 1 atom of one of them, with 1 atom of the other; or 1 atom of one, with 2 atoms of the other; or 2 atoms of one with 3 atoms of the other, and so on for any number of atoms; then it will follow, that, in any com- pound, whose constituents, there is reason to believe, unite atom with atom, the relative weights of such atoms must 142 ACCOUNT OF THE ATOMIC THEORY Book I. be proportional to the relative weights of the constituent! Division I. themselves. Thus if oxygen and hydrogen be supposed to unite one atom with one atom, when they combine to form water; then since the weight of the hydrogen is to the weight of the oxygen as 1 to 8; therefore, if the weight of an atom of hydrogen be assumed as 1, the weight of an atom of oxygen will be 8. the occur- Now, if it be reasonable, in the nature of things, to I?uce ?ffi suppose that bodies unite atom to atom; and if, upon assura- niteTpro-" ing the supposition as true, it be found that the proportions, portions in which the constituents of the bodies most familiar to the counted"^ chemist combine, tally exactly with it; is not the conclu- most satis- sion almost irresistible, that such supposition is not only factor,|y> by reasonable, but absolutely true, in the nature of things. supposing . ' / ' . . ° that bodies If it be asked, what data the chemist has tor supposing •orabioe that hydrogen and oxygen unite atom with atom, and not in by atoms, any other atomical proportion; the answer is that hydrogen which have an(i oxvgen combine in one known proportion only; and weights. tnat it is not probable that any other proportion of combi- nation will hereafter be discovered. Accordingly it is rea- sonable to suppose that, if hydrogen and oxygen unite ato- mically, they combine atom with atom. Upon any other supposition, it would become necessary to consider the only compound of oxygen and hydrogen known, as one in which the constituents unite in unequal numbers of atoms. The suppo- The reader, it is believed, will be ready to allow, there- sition of fore, that if hydrogen and oxygen unite atomically, the tion by union takes place atom with atom; and if so, that, taking atoms, as- the weight of an atom of hydrogen as 1, the weight of an sumeu: and . /- • «« ■ _ thei,. atom ot oxygen will be 8. weights in The supposition of atomic combination will now be made bodtes de- w*th regard to several other compounds; and first to hydro- duced from chleric (muriatic) acid. This acid is composed of 1 part of data"" hydrogen united to 36 parts of chlorine. Now supposing its constituents united atom with atom; the weight of an atom of hydrogen being taken as 1, the weight of an atom of chlorine will be 36. Hydriodic acid is composed of 1 part of hydrogen, united to 125 parts of iodine. Now if this be a compound, in which the constituents unite one atom with one atom; then the relative weight of an atom of iodine will be 125. Hydrosulphuric acid (sulphuretted hydrogen) is com- posed of 1 part of hydrogen, united to 16 parts of sulphur. Supposing this to be a combination of one atom with one atom also; then the relative weight of an atom of sulphur will be 16. Thus, taking the weight of an atom of hydrogen as one (and ACCOUNT OP THE ATOMIC THEORY 143 unity will always be assumed to express the atom of this Chap. v. body) then the relative weight of the atom Of Chlorine will be 36 Of Iodine 125 Of Sulphur 16—as deduced from the composition ot the three acids just mentioned. The relative weights of the atoms of these same bodies will now be deduced from their combinations with oxygen. Oxygen combines in four proportions with chlorine. The con pounds formed are composed as follows: 1. Protoxide of chlorine, of 8 oxygen + 36 chlorine. 2. Deutoxide of chlorine, of 32 ■ + 36 —-—— 3. Chloric acid, of 40 ---- + 36 ----— 4. Oxychloric (perchloric) acid, 56 ---- + 36 ——— Now as the protoxide ot chlorine is the particular combi- nation, between oxygen and chlorine, in which the constitu- ents combine atom with atom, for reasons of general applica- tion, which will be given hereafter; the relative weight of an atom of chlorine must be deduced from this oxide: and it is perceived, that it turns out to be the same, as when deduced from the combination of this same suppor- ter with hydrogen. It is also perceived, that the deutoxide contains 4 times, chloric acid, 5 times, and oxychloric (perchloric) acid, 7 times as much oxygen, combined with the same quantity of chlorine, as the protoxide. Here then the chemist infers that these compounds are composed of 1 atom of chlorine, combined respectively with 4 atoms, with 5 atoms, and with 7 atoms of oxygen. Iodic acid is the only compound formed between iodine and oxygen; it is composed of 8 oxygen + 25 iodine; or, which is the same thing, of 40 —— +125 ---- From the above numbers, it is necessary to infer, either, that the atom of iodine is rated 5 times too high, as deduc- ed from its combination with hydrogen; or that the com- pound in question contains five atoms of oxygen. The lat- ter inference is by far the most probable; since the weight of an atom of iodine, deduced from a number of its com- pounds, turns out to be the same as when calculated from hydrogen. Oxygen forms with sulphur three compounds, which are composed as follows: 1. Hyposulphurous acid of 8 oxygen + 16 sulphur. 2. Sulphurous acid of 16 —— + 16 —— 3. Sulphuric acid of 24 —— +16 ____ 144 ACCOUNT Or THE ATOMIC THEORY. Book I. Supposing hyposulphurous acid to be the particular com- Div'"on *• pound of the three, in which the constituents are united in the simplest atomic manner; then it is obvious that the weight of the atom of sulphur will be 16, the same number assigned for it, from the consideration of its combination u ith hydrogen. It is also obvious, from the foregoing state- ment, that sulphurous acid contains two, and sulphuric acid, three atoms of oxygen, united with one atom of sul* phur. These The fair conclusion to be drawn from the above state- deduced,80 rnents is, that the same relative weights, for the atoms ot turn out to chlorine, iodine, and sulphur, are deducible from the foVthe33"16 combinations of these bodies, with either hydrogen or oxy- same body. gen. If then, there is good reason to believe that the rela- tive weights, of the atoms of chlorine, iodine and sulphur are correctly stated at 36, 125, and 16 respectively; it may be matter worthy of inquiry, what relative weights would be assigned to these same bodies by the consideration of the combinations formed between themselves. These combinations are chloriodic acid, chloride of sulphur, and iodide of sulphur. One only of these substances has been accurately analyzed; and the proportion, in which its con- stituents combine, confirms the statement above given. Thus chloride of sulphur is composed of 36 parts of chlo- rine united to 16 parts of sulphur. Chloriodic acid and iodide of sulphur afford no data; as their composition it not correctly known. In the foregoing bbservations, the reader has been told that bodies probably combine by atoms: and that when- ever there is good reason to believe that the constituent* of any body combine one atom with one atom; then the num- bers which express the relative weights of such constitu- Howacom-ents, represent also the relative weights of their atoms. But, bination in ft may De asked, what are the indications which make it proportions probable, when several different compounds are formed is to be from the same constituents combining in different propor- tions, that some one of them is formed by the union of one atom with one atom; and not by the union of an unequal number of atoms. To illustrate this question, it will be convenient to ad- duce an instance, in which a number of compounds are formed from the same constituents, united in different pro- portions; and to consider them with the view to determine, in which of them the constituents unite in the simplest pro- portion, or one atom with one atom. ACCOUNT OF THE ATOMIC THEORY. 145 Thus the Cbap v- Protoxide of azote is composed of 14 azote + 8 oxygen. Deutoxide of azote.....14 + 16 Hvponitrous acid......14 +24 Nurous acid.......*4 +32 Nitric acid........*4 + 40 or the Protoxide of azote is composed of 40 oxygen + 70 azote. Deutoxide of azote.....40 +35 Hvponitrous acid......40 + 23-3 Nitrous acid.......40 +17*5 Nitric acid........40 + 14 If it be supposed that nitric acid is a compound of one atom of oxygen and one of azote; then it is seen, by the last statement of those just given, that nitrous acid will be made to be a compound of one atom of oxygen, and one atom and a fraction of azote; or if the azote be taken at the same number in both these acids, then the latter will be made a compound of one atom of azote, and a fraction of an atom of oxygen. Now neither of these suppositions is tenable, consistently with the nature of an atom. If it be supposed, that the protoxide of azote is a cdmpound of one atom of azote, and one atom of oxygen; then the deu- toxide is either a compound of one atom of oxygen and half an atom of azote, or of two atoms of oxygen and one atom of azote; as will be seen most clearly by the statement last given. Now the last supposition may be held consistently with the atomic theory; and therefore there is nothing in the suppo- sition that the constituents of the protoxide unite atom with atom, which is inconsistent with an atomic composition for the deutoxide. But it is necessary that no atomic inconsis- tency should exist upon viewing the other compounds of azote and oxvgen; otherwise the atomic assumption alrea- dy made would be untenable. Now it is seen by the first statement, that, without atomic inconsistency, hyponitrous acid may be considered a compound of 1 atom of azote, united to 3 atoms of oxygen; nitrous acid, of 1 atom of azote, united to 4 atoms of oxygen; and nitric acid, of 1 atom of azote united to 5 atoms of oxygen. It may, indeed, be said that the deutoxide of azote is a compound of 1 atom of oxygen, united to 1 atom of azote; and that the protox- ide is composed of 1 atom of oxygen united to 2 atoms of azote; and as far as this supposition goes, there would no atomic inconsistency in it. But when the same atomic sup- position is attempted to be applied to the other compounds of azote, it will be found entirely to fail; as it will make a resort to a fractional atom unavoidably necessary. T 146 ACCOUNT OF HIE ATOMIC THEORY Book i. It is difficult to give a concise rule, for determining when Division l a combination takes place in the simplest proportion, or one atom of one constituent with one atom of the other; but it may be stated in general terms, that the particular combi- nation between any two substances, uniting in several pro- portions, is the simplest, of either of the constituents of which, the same constituent, in every other compound of the same ingredients, may be some exact multiple. What has The facts and reasonings, upon which the atomic theory be^.ncisean''119 rests, are too diversified to allow a full enumeration of enable any them to be made in this place. All that is intended by the one to satis- imperfect sketch, which has just been completed of this trfthTtruth theory, is to enable the student, by means of the outline or falsity of given, to test its accuracy, by pursuing the subject In all the atomic • -r theory. lts ramifications. This may very easily be done by any one, who will take the trouble of examining any compound already described, the composition of which is ascertained with tolerable ac- curacy. The numbers in all the analyses, already given, are made to accord with the atomic theory, as far as the results of actual experiments would warrant. The weightj of the atoms are all compared with the weight of an atom of hydrogen; which is assumed as unity in conformity with Mr. Dalton's plan. Every analysis, which was found not to accord with any supposition of atomic combination, is distinguished by an asterisk. But in all such cases, the equivalent number of the substance, under which the analy- sis is given, is assumed; whilst the amount of the body, with which it may combine, is calculated proportionally. Reasons for It may appear strange to the reader, that he is introduced ha H°g 'd to a knowledge of the atomic theory, for the first time, at the atomic a pe.riod when the work has considerably progressed; and theory at that he has been studying numbers adjusted in conformity the8 present wn^ a theory, about which he should be presumed to know work. nothing. But the object of this course is easily explained. The student could not, with any prospect of advantage, have been made acquainted with the atomic theory at the very threshold of his inquiries. He is then presumed to know very little of chemical science; and consequently, not to be in possession of the data, without which, it would be im- possible for him to understand the subject. But, after he had been made acquainted with these data to a sufficient extent, by pursuing part of the work; it became expedient to bring forward the theory, in order that the remainder might derive every possible advantage from its application. Nothing as yet has been said of the rise and progress of the theory, which has just been attempted to be described. ACCOUNT OF THE ATOMIC THEORY. 147 It appears to be generally admitted, that the idea of bodies Chap. v. uniting chemically by particles or atoms, was first suggest- idea of " ed by Higgins in 1789. Many facts respecting definite pro- combina- portions were afterwards ascertained by Dr. J. B. Richter,^^^^ between the years 1T92 and 1802. It was this chemist, who suggested discovered, that, upon the decomposition of neutral salts, [jf ^gg8"18 the resulting salts preserved a neutral state also; and, fur- ther, that whatever quantities of the acids were found to sa- turate any particular salifiable base, proportionate quanti- ties would saturate every other base; and conversely, what- ever quantities of salifiable bases were sufficient to saturate any particular acid, proportionate quantities would saturate every other acid. These facts led very directly to the sup- position of atomic combination; but it does not appear that Dr. Richter drew any conclusion from them of this kind. It was reserved for Mr. Dalton to put forth the atomic Dalton, theory, supported by such evidences as to render it almost now«ver» ii i • , rrn • i - i . . ■ . msybecon- universally admitted. I his chemist, who may be considered sidered the the author of the theory, as early as the year 1802, began to real author perceive many facts, which led to the supposition of defi- mjc theory. nite proportions, and atomic combination; and, in successive years, the theory has been gradually matured, so that, at the present time, it wears every appearance of truth; and, from its tendency to establish fixed relations between the numbers, expressive of chtmical combination, may be justly reckoned one of the most important discoveries yet made in chemistrv. Having thus finished the account of the atomic theory, Weights of the reader may be presented, with advantage, with thethe atom» weights of the atoms of each of the undecompounded pon- decom-Un" derable bodies, as far as they have been ascertained. pounded Statement of the weight of the Atom of each of the Undecom- bodies!^ pounded Ponderable Bodies.* 35. Manganese 36. Cerium 37. Uranium 1. Oxygen 2. Chlorine 3. Iodine 4. Fluorine 5. Azote 6. Hydrogen 7. Carbon 8. Horon 9. Phosphorus 10. Sulphur 11. Arsenic l£. Chromium l.>. Molybdenum 14. Tungsten 15. Columbium 16. Selenium 17. Antimony 8 36 125 14 1 6 12 16 47« 28' 48" 96« 146* 40' 45" 18. Tellurium 19 Potassium 20. Sodium 21. Lithium 22. Calcium 23. Barium 24. Strontium 25. Mxgnesium 26. Yttrium 27. Glucinum 28 Aluminum 29. Zirconium 80. Thorinum 31. Silicum 32 Iron 33. Nickel 34. Cobalt 32 40 24 10 21* 70 44 12* 28 27 29 28" 38. Zino 39. Lead 40. Tin 41. Copper 42. Bismuth 43. Mercury 44. Silver 45. Gold 46. Platinum 47. Palladinm 48. Rhodium 49. Iridium 50 Osmium 51 Titanium 125* 33 104 59 64 71* 200 110 200* 56* * All the numbers in the table cannot be deduced from analyses already given but they will be confirmed by compositions, which will be laid before the reader during the progress of the work. 148 COMPOUND PONDERABLE BODIES. BaoK i. The weight of the atom of those substances, whose cor- Division "• relative number is distinguished by an asterisk in the pre- ceding table, is to be considered as approximated only. Advantages As the numbers above given have the same ratio to each to be gained other, as the weights of the atoms, which they respectively le7ctJng°the represent; it must be obvious, that, whenever two bodies equivalent unite in the simplest proportion, they unite in the ratio tx- etamiieiS °f Passed by their equivalent numbers. Hence if the equiva- bodies. lent numbers be recollected, the ratio in which any combi- nation takes place in the simplest manner, must also be known. For example, if it be borne in mind, that the equi- valent number for sulphur is 16, and for chlorine 36; then it will be known that if sulphur and chlorine combine in a simple proportion, it is in the ratio of 16 to 36: again, if it be recollected that the equivalent number for oxygen is 8, and that for azote 14, and also that nitric acid is com- posed of 1 atom of azote combined with 5 atoms of oxygen; then it may be at once deduced, that, in nitric acid, the azote is to the oxygen as 14 to 40. DIVISION II. OF COMPOUND PONDERABLE BODIES. sons Some com- Many of these bodies have been already described, when pound bo- treating of the different undecompounded bodies. Of course, dynoticed, under this head, those compound ponderable bodies only, not heretofore described, will find a place. It may not be very obvious, why some of these bodies are described under the undecompounded bodies; while others and for are reserved for this division of the work. Various reasons, whatrea- however, have operated in determining where different com- pounds should stand. The chlorides, iodides, sulphurets, phosphurets and carburets, are described under the unde- compounded ponderable bodies; because their descriptions are generally short; and by standing near the bodies of which they are formed, the association of the compound with its most important constituent is more direct and better preserved. The alkaline and earthy salifiable bases are reserved for this part of the work; because, they are important in themselves, and require a separate description. On the other hand, the remaining salifiable basts (usually called metallic oxides) are treated of under the metals of which they are formed; because, generally speaking, their individual importance is not very great. AMMONIA. 149 The compound ponderable bodies will be treated of un- Chap. I. der the four heads of Compound Salifiable Bases. ponderable . * bodies, con- Acids. sidered un- Salts. t'er wur Unsalifiable Compounds; and will formheada the subjects of as many chapters. After the chapter on acids has been completed; the term acid, in the chemical sense, will be explained; and some account will be given of the principles of the classification of acids, pursued in the pre- sent work. These subjects will be embraced in a separate ohapter. CHAPTER I. OF SALIFIABLE BASES. The salifiable bases will be divided into the three follow- Salifiable bases, ui- ing classes. Tided into I. Alkaline salifiable bases. three class- II. Earthy salifiable bases. III. Salifiable bases, having neither alkaline nor earthy properties. CLASS I. ALKALINE SALIFIABLE BASES. The alkaline salifiable bases are: 1. Ammonia, 4. Lithia, 7. Strontian, Alkaline 2. Potash, 5. Lime, 8. Magnesia. salifiable D&968 ClaU™ 3. Soda, 6. Barytes, merated. They will be treated of, in the order in which they have been enumerated, in the eight following sections. SECTION I. OF AMMONIA. Common names, Volatile Alkali.—Hartshorn. I. Ammonia may be obtained by exposing a mixture of Ammonia; three parts of quicklime, and one part of hydrochlorate of howobtain- ammonia (sal ammoniac) in powder, in a retort, to the heat 150 ALKALINE 9ALTHABLE BASKS. Book I. of a lamp. A gas is formed, which must be collected over Division II. mercurv. This gas is ammonia. Process ex- II. Hydrochlorate of ammonia is a salt composed of plained. hydrochloric (muriatic) acid, and the substance under des- cription. By being heated with lime, it is decomposed; the hydrochloric acid forms with the latter substance, chloride of calcium and water, while the ammonia is disengaged. Process HI. Ammonia is obtained, by the manufacturer, by the themanu-7 destructive distillation of all animal substances (except fat), facturer. which have not suffered spontaneous decomposition. The substances generally employed are refuse bones and the pith of horns. The distilled product is an impure ammonia, partly in a concrete state and partly dissolved in water, containing a portion of carbonic acid and some empyreuma- tic oil. To be obtained pure, it is first saturated with sul- phuric acid, and then converted into hydrochlorate of am- monia by double decomposition with chloride of sodium (common salt). The hydrochlorate is made to yield up its ammonia in the manner just described. Discorery. IV. This gas was first obtained in a pure state by Dr. Priestley. Besides the names already given, it formerly had several others; such as spirit of urine, because it was ob- tained by the distillation of urine; and spirit of sal ammoniac, because it was sometimes obtained from sal ammoniac. Properties. V. Ammonia is a gaseous substance, transparent and colourless like air. Its taste is acrid and hot; and its smell, exceedingly pungent. It changes vegetable blues to green. When exposed to a cold of — 45°, it assumes the liquid form; but becomes a gas immediately, if the temperature be rais- ed. When passed through a red hot tube it is decomposed. Spec. grav. VI. It is a very nearly six-tenths as heavy as common 0-590. air< Itcannotbe VII. Ammoniacal gas is, strictly speaking, unrespirable: theTun"st0 w^en l^e attempt is made to draw it into the lungs, the glottis closes spasmodically. It does not support combus- tion: when a lighted candle is let down into it, its flame is extinguished; but, previously to that effect taking place, at the moment of immersion, it is enlarged by being surround- ed by another flame of a pale yellow colour, which descends from the top to the bottom of the containing vessel. Ammo- niacal gas, although containing a combustible substance, will Burns un- not burn in atmospheric air; but when expelled from a tube derpecu- with a narrow orifice, and surrounded by oxygen gas, it stances on- burns with a pale yellow flame; water being formed and 'y- azote liberated. Combines VIII. This gas combines very readily with water, and Md'fcrmiT forms the compound called liquid ammonia. AMMONIA. 151 Chap. 1. LIQUID AMMONIA. H ater of Ammonia of the Edinburgh College. 1 This combination takes place whenever ammoniacal gas liquid am- comes in contact with water. The union is attended by an monia- increase of temperature, as well as of the bulk of the water employed. 2 The Edinburgh college directs the following process, Liquid am- for the preparation of the water of ammonia: To two pounds ™Z'e4 of quicklime, previously slaked by one pound ot water, for medicai and placed in a retort, add one pound of hydrochlorate of use. ammonia (sal ammoniac), dissolved in five pounds ot wa- ter. Shut the mouth of the retort, and mix the substances by agitation. Now distil into a refrigerated receiver, with a gentle heat, until twenty ounces of liquid have been ab- stracted. 3. The above process agrees with that given for the pre- its proper- paration of pure ammonia; except that the presence of wa-t,es- ter, in the latter, causes the ammonia to come over combined with that liquid. 4. Liquid ammonia is the usual form, in which ammonia is employed by the chemist. When it is heated to the tem- perature of 130°, the ammonia separates in the form of gas: When exposed to a cold of — 46°, it crystallizes. If sud- denly cooled to — 68°, it assumes the appearance of a thick jelly; having scarcely any smell. 5. Liquid ammonia is capable of dissolving the oxides of Dissolves silver, copper, iron, tin, nickel, zinc, bismuth and cobalt. ?%™^ It deoxidizes the oxides of mercury, lead and manganese; deoxidizes water being formed, and azotic gas emitted. others. 6. Water, when saturated with ammonia, contains 670 Composi- times its bulk of the gas, which amounts to about one-third Jj™ °^o of its weight; and its specific gravity is reduced to *875.. „ia. 7. Liquid ammonia is a very powerful stimulant. It is Medical not often given internally, because other preparations for JJJg jj^ internal use, are preferred. When applied to the skin, it acts nja. powerfully as a rubefacient, and is used with a view to this effect in chronic rheumatism and in paralysis. The ammo- niacal gas, which exhales from it, stimulates strongly the nose and eyes. When applied to the nose, it constitutes a very- efficacious stimulant in syncope. It is sometimes applied to the eyes in chronic ophthalmia. IX. A mixture of ammoniacal gas with oxygen may be Ammonia- fired by the electric spark. If the oxygen be in excess, partcai andoxy' of the ammonia is decomposed, and nitric acid and water fired by the are obtained; the former of which combines with the un- el*0*™ decomposed portion, and forms nitrate of ammonia. 152 ALKALINE SALIFIABLE BASES. Book i. X. When pure ammonia is mixed with chlorine gas, Division II. combustion takes place, and it is partially decomposed. The Effects of azote of the decomposed portion is evolved: while its hy- ed with'X dr0Sen combines with the chlorine, so as to form hydrochlo- ehlorine. ric (muriatic) acid; which then unites with the undecom- posed portion, and forms hydrochlorate of ammonia (sal ammoniac). Sulphuret XL The sulphuret of ammonia may be formed by causing of ammo- ammonia to come in contact with sulphur in a state of va- pour. Its properties have not been investigated. XII. Ammonia does not appear capable of combining with the metals. Whenever it appears to dissolve them, it is after having oxidized them at the expense of the water, with which it is combined. Ammonia XIII. Ammonia combines with the oxides of gold, of sil- combmes ver^ antj Qf platinum, and forms compounds, called fulminat- ofgold, ing gold, fulminating silver, and iulminating platinum. forming j. Fulminating goId may be prepared by dissolving gold goi™ina ,ng in aqua regia, diluting the solution with thrice its weight of water, and adding to it, by degrees, liquid ammonia, as long as any precipitate appears. The precipitate thus obtained must then be washed in pure water, and dried slowly on filtering paper. It is now fulminating gold, or the ammo- niuretted oxide of gold. To prevent accidents, the phial, in which it is kept, must not be corked; but its mouth covered with a piece of linen or paper. 2. Fulminating gold is a yellow powder. It has its name from the property of exploding whenever it is violently struck. The cause of this property is the sudden decompo- sition of the powder. The hydrogen of the ammonia com- bines with the oxygen of the oxide, forming water; the gold is reduced, and the other constituent of the ammonia, (azote) suddenly assumes the elastic form, and gives rise to the explosion. with oxide 1. Fulminating silver is formed by allowing liquid am- of silver, m0nia to stand for twelve hours, upon the precipitate form- forming ful- ... .. ,. r -i i i- r™ minating ed, in the nitric solution ot silver, by lime water. 1 he pre- Bilrer: cipitate must then be separated, and dried in very small portions upon filtering paper. It is now fulminating silver. 2. This powder, even when moist, explodes violently when struck; when dry, the same effect is produced by the least touch. The explanation of its explosion is the same with that given of the same property in fulminating gold. 'xkteof1 *" Culminating platinum is formed by digesting the pre- pbtinum, cipitate, formed in a solution of platinum in aqua regia by ibrmingful-hydrosulphuric acid (sulphuretted hydrogen), in nitric acid, AMMONIA. 153 until it is converted into sulphate of platinum: this sulphate, Chap, i^ being dissolved in water, is then precipitated by liquid minating^ ammonia; the precipitate formed, after being washed, isP1*1"""™- boiled for some time, with a solution of potash, in a Florence flask, and then separated by the filter. The powder, thus obtained, after being washed and dried, con- stitutes fulminating platinum. 2. Fulminating platinum is a brown powder. It does not explode by trituration or percussion, but by exposure to heat, very violently. XIV. Ammonia is composed of Ammonia, Hydrogen 3—three atoms. composed Azote U-one atom. J^Jj- Giving 17 for the number representing the atom of this alkaline base. XV. The nature of ammonia was gradually developed by Discovery the labours of Scheele, Priestley, and Berthollet. Scheele °fitscom- j. 11 i • • i j i_ • position. discovered, that when ammonia is decomposed by certain metallic oxides; the oxides are reduced, the gas disappears, and a quantity of azote is found in its place. Priestley as- certained, that, when heat is applied to the peroxides of lead and mercury, confined in ammoniacal gas; these oxides are reduced, water is formed, and, in the place of the am- monia, a quantity of azote is found. The results, obtained by these chemists, led to the conclusion, that ammonia is a compound of azote and hydrogen; an opinion, afterwards amply confirmed by Berthollet. XVI. A galvanic experiment, made by Berzelius and Ammonia, Pontin, gave reason to believe, at one time, that ammonia *uPP°sed to was composed of a metallic radical, united to oxygen. uc oxide. These chemists found, upon negatively electrifying mer- cury, in contact with a solution of ammonia, that a globule was produced, having the metallic lustre, and a volume, five times as great as the mercury employed. The conclusion, which they drew from the phenomena of this experiment, was, that this globule is an amalgam formed with some metal, previously unknown, and probably the radical of ammonia. The experiment of Berzelius and Pontin was re- peated, with the same result, by Davy; who was inclined to coincide, in opinion, with these chemists, with regard to the nature of the globule. The conclusions, drawn from the experiments of Berzelius and Pontin, going to establish a perfect analogy between all the salifiable bases, were received, rather favourably, by the chemical world. The subsequent experiments, how- ever, of Gay-Lussac and Thenard, made with great care, U 154 ALKALINE SALIFIABLE BASES. Boost, induced these chemists to conclude, that the supposed Pi™"" "• amalgam is, in reality, a compound of mercury and am- monia; and, at present, the general impression is very much in favour of their opinion. SECTION II. OF POTASH. Syn. Pure Kali.—Caustic Vegetable Alkali. Potaihi I. The only method to obtain potash, absolutely pure, is to how obtain- expose the peroxide of potassium to a sufficient heat, to edpure. drive off the second dose 0r oxygen, which it contains. In this way, perfectly pure potash was first obtained, by Sir H. Davy. For the common purposes of the chemist, however, the hydrate* of potash, or potash pure in every respect, except that of containing a portion of water, in the solid form, is sufficiently pure; and, when potash is spoken of, in any part of this volume, it is the hydrate, which is meant; unless otherwise particularly specified. Howob- II. Berthollet's method for obtaining potash, is the thTstate of following: Mix any quantity of the pearl-ash of commerce, hydrate, with twice its weight of lime, and ten times its weight of water. Put the mixture in a close glass vessel; and let it stand for forty-eight hours, shaking it occasionally. Filter the liquid, and then boil it rapidly, in a silver vessel; until upon cooling, it may be able to assume the consistence of honey. Now add to it, a quantity of alcohol (spirit of wine) equal to one-third of the pearl-ash, originally employed. After having shaken the whole, boil it for a few minutes, and then pour it into a glass vessel; which must then be tightly corked. By degrees, the mixture separates into two portions; the upper portion must be decanted into a silver basin, and evaporated rapidly, until a crust form upon its surface. It is then to be poured into a porcelain vessel, and allowed to concrete. The substance, thus obtained, is potash. The last III. The pearl-ash of commerce is an impure carbonate pUrined eX"°f potash. Now lime has a stronger affinity for carbonic acid, than potash has; and, therefore, in the process just given, it separates the greater part of this acid from the pearl-ash. The lime becomes converted into carbonate of Hydrates are solid compounds, which contain combined water. POTASH. 155 lime (chalk), which is insoluble; and the pearl-ash, into a Chap. I. mixture ot pure potash, and undecomposed carbonate. Fil- tration removes the carbonate of lime. Alcohol possesses the property of dissolving potash, but does not act upon its carbonate. The treatment, therefore, of the filtered liquid, with alcohol, results in the formation of an alcoholic solu- tion of potash, free from admixture of the carbonate. This solution swims on the surface, and is separated by being decanted. The rapid evaporation, to which it is after vards subjected, drives off the alcohol, and leaves the potash pure. IV. The Edinburgh college directs the following process Prepara- for obtaining potash: Evaporate the solution of potash,* Uon"t Pot" until ebullition cease, and the liquid flows like oil. Whenjicai use. this happens, the water of the solution will have been driven off. Now pour the liquid on a smooth iron plate; and, before it hardens, divide it into small pieces, and keep them in well stopped phials. The precaution, last mentioned, is necessary, to prevent the absorption of car- bonic acid. V. Potash, obtained by either of the processes last Properties described, is a solid white substance, having an unctuous potMh' feel, and an extremely acrid taste. Its smell resembles that, which is perceived during the slaking of lime. It changes vegetable blues to green. It is deliquescent in the air. After being exposed to a red heat; it still contains water, to the amount nearly of 16 per cent. VI. It is about one and three-fourth times as heavy as Spec grav. water. i7°- VII. Potash dissolves readily in water, and forms a so- Potash lutioo, which will be called liquid potash. ^'™*> *ith LIQUID POTASH. quid potash. fFaUr of Potash, of the Edinburgh college—commonly called Caustic Lie. 1. The process of the Edinburgh college, for preparing Liquid pot- this solution, is the following: Mix eight ounces of lime*8n!.now with twenty-eight ounces of warm water: the lime will mSS?6* slake violently, and cause the ebullition of the mixture. As use. soon as this is over, add instantly six ounces of carbonate of potash (salt of tartar); mix the whole, and let it stand to cool, in a covered vessel: the carbonic acid becomes trans- ferred to the lime, which is thereby converted into carbo- nate of lime; while the pure potash remains in solution. After the mixture has cooled, agitate it well to mix its * Solution of potash is an officinal preparation, to be mentioned presently. 156 ALKALINB SALIFIABLE BASES. Book I. several parts; and then filter it gradually, from a covered Dlv'si""n- glass funnel, whose throat is obstructed by a piece of dean linen, and whose tube is inserted into a glass vessel, to re- ceive the filtered product. As soon as the liquid should cease to drop; add, cautiously, to the mixture in the funnel, a few ounces of water, in such a manner, as that the latter may swim on the surface of the toraier. This addition causes the liquid again to drop; and similar ones are to be repeated, until three pounds of the filtered liquid are pro- cured; which quantity will be obtained alter the lapse of two or three days. The object of the filtration is to separate the insoluble carbonate of lime, which remains upon the funnel; nothing passing through but the solution ot the potash. Water is directed to be added occasionally, until the filter- ed liquid shall amount to three pounds; in order that the solution, being intended for medical use, may always be prepared of the same strength. The solution must be kept in well stopped bottles, in order to guard against the ab- sorption of carbonic acid. Properties 2. Liquid potash is transparent, and has the consistency of i..|uid of oil. It is in this form, that potash is usually employed potash. ^y chemists. When it is a saturated solution, it contains about two-thirds of its weight of potash. Its medical 3. Liquid potash has enjoyed, at various times, con- uses, siderable reputation, as a solvent of calculi. It has, un- doubtedly, relieved many cases of stone; but, in many others, it has totally failed. This difference, in its effects, is explained, by supposing the existence of a different kind of calculus, in the various cases, in which it has been used. Modern chemistry has thrown great light on the nature of urinary concretions. It has ascertained them to be of a great many different kinds. Some are soluble in potash, and in soda; while others dissolve only in the acids. Now, it appears, that the solution of potash is best suited to the former kind; which are found to consist of a certain acid, called by chemists uric acid, either alone, or combined with ammonia. To ascertain the nature of the calculus, which may exist in any particular case, it is necessary to subject the urine to a chemical examination. When it is determined to use the solution of potash, in a case of calculus, it must be ordered in a very diluted state. Besides its use by the mouth, it has been proposed to inject the solution into the bladder, in cases to which an alkaline solvent may be suited. When this is done, the bladder must be evacuated, and washed out with tepid water. The solu- tion, made so dilute as to admit of being held in the mouth without uneasiness, is then injected into the bladder, and POTASH. 157 allowed to remain there for half an hour. After it is Chap. I. evacuated, it is to be tested for the presence of calculous ~ mutter in solution. VIII. Potash, when not in the state of hydrate, may be Potash made to combine with an additional dose of oxygen. It is ^.jf™" thus converted into peroxide of potassium. gen-, IX. Dr. Thomson has recently ascertained, that potash a„d with is capable of forming a chloride. This chemist succeeded, chlorine. in obtaining it, by double decomposition, from a salt of pot- ash, and chloride of lime. The latter chloride, he found, to constitute the principal part of Mr. Tennant's bleaching salt.* If potash, however, be heated to redness in chlorine gas; chloride of potassium, and not chloride of potash, is form- ed; oxvgen being at the same time evolved. Potash suf- fers a similar decomposition, when heated in contact with iodine. X. Potash combines, in one proportion, with sulphur; Sulphuret and forms sulphuret of potash. * of pou*h; 1. Sulphuret of potash, formerly called liver of sulphur, how form- may be formed, by fusing together, two parts of carbonate ed- of potash (salt of tartar) and one part of sulphur. The car- bonate becomes decomposed; the carbonic acid is liberated, while the potash combines with the sulphur. 2. Sulphuret of potash is a hard and brittle substance, of Its proper- a liver-brown colour. It has a vitreous fracture. Its taste istie8, acrid, caustic, and bitter. Its smell resembles that of sublim- ed sulphur. It deliquesces, and suffers decomposition, in the air. It is very fusible. It has not hitherto been analyzed. XI. Potash is incapable of uniting with the metals; but, Potash,in when in a state of solution, it is capable of oxidizing seve- solution, ral of them. These metals are zinc, iron, tin, and osmium, some me- lt is capable of dissolving the oxides of the following tais. metals; namely, arsenic, molybdenum, tungsten, antimony, tellurium, nickel, cobalt, manganese, zinc, lead, and tin. XII. Potash is composed of Composi- Potassium 40—one atom. tion of pot- Oxygen 8—one atom. Giving 48 for the number represent- ing the weight of its atom. XIII. Potash decomposes, almost instantaneously, ani-Uses to the mal substances of all kinds. This property makes it useful to 8urSeon- the surgeon, for the purpose of destroying fungous flesh, or excrescences; and for opening abscesses. It is from this ap- plication of it, that it is called, in common language, caustic. • Annals of Philosophy (Mar. 1819.) p. 185. 158 ALKALINE SALIFIABLE BASES soda in na- ture. SECTION III. OF SODA. Common names, Caustic Fossil Alkali.—Caustic Mineral Alkali. Soda; how !• Soda, absolutely pure, was first obtained by Sir H. obtained Davy, by burning sodium in a quantity of oxygen gas, just sufficient to convert it into soda. When thus prepared, it has a grey colour, and presents, when broken, the vitreous fracture. For fusion, it requires a strong red heat. When water is added to it, it becomes solidified; and the soda is converted into a hydrate. When the word soda is used, in chemical descriptions, it is this hydrate which is always meant, unless Otherwise specified. How ob- II. Tne best method for obtaining soda, pure in every tamed in . , , _ r . . ° . r , ' the state of other respect than that of containing water, is to decompose hydrate, the soda of commerce, commonly called barilla, which is a carbonate of soda, by means of lime; and afterwards to treat the resulting mass with alcohol. The manipulations of the process, and its explanation, are exactly similar to those given, when describing the preparation of potash. Sources of HI. Soda is obtained from several different sources io nature. It may be extracted from common salt; which is a compound of sodium, the radical of soda, and chlorine. It is found, in large quantities, combined with carbonic acid, in Egypt, and in several other parts of the world. The ashes of many sea plants, especially of those belonging to the genus salsola, yield it in considerable abundance. IV. Soda was confounded with potash, to which it bears considerable resemblance, until Du Hamel, in 1736, point- ed out its distinguishing properties. The conclusions of Du Hamel were afterwards confirmed by Margraff. Properties V. Soda is a greyish white solid; agreeing exactly with of soda. potash, in taste, smell, and the action which it exerts upon animal substances. It changes vegetable blues to green. It is readily soluble in water. When exposed to the air, it ab- sorbs moisture and carbonic acid; assumes, at first, the consistence of paste; but, afterwards, becomes dry, and crumbles into powder. Under similar circumstances, pot- ash would liquefy. The different manner, in which exposure to air affects potash and soda, affords a very obvious crite- rion for distinguishing these alkaline bodies. Spec. grav. VI. Soda is about one and one-third times as heavy a» 1-33. Water. It is, therefore, considerably lighter than potash. Soda com- VII. Soda is capable of combining with an additional oxygen!th dose of ox-vSen»' whereby it is converted into peroxide of LITHIA. 159 sodium. This oxide has already been described under the Chap. I. head of sodium. VIII. Soda may be made to form a chloride, by double and with decomposition, between a salt of soda, and chloride ofchlonne- lime. This tact has Ken lately ascertained by Dr. Thom- son.* When, however, soda is heated in chlorine gas, it is de omposed, and chloride of sodium (common salt) be- comes formed. Soda undergoes a similar decomposition, when heated in contact with iodine. IX. Soda is composed of Composi- Sodium 24—one atom. tion oisoda. Oxygen 8—one atom. Giving 32 for the number representing the weight of its atom. X. Soda enters, as a constituent, into many important Soda, a con- chemical medicines. Its medical properties will be noticed stitu^ntma i r !•#- i • i i ■ • number ot hereafter, as moained in these combinations. medicines. SECTION IV. OF LITHIA f I. Lithia is an alkaline salifiable base, which has been Minerals latch discovered by Mr. Arfwedson of Sweden. It occurs w.h|* *jjr" to the amount of five or six per cent, associated with alu- mina and silica, in the mineral called pelatile, where it had been previously mistaken for potash. It is present also, in triphane, in the proportion of eight or nine per cent, asso- ciated with alumina, silica and oxide of iron; and it con- stitutes about four parts, in the hundred, of green tourma- line (crystallized lepidolite) where it is present along with alumina, silica, boracic acid, and the oxides of iron and of manganese. II. It was discovered in consequence of its very high neutralizing power. When saturated with an acid, in the course of the analysis of petalite by Arfwedson; the calcu- lated amount of salifiable base present, under the supposi- tion that it was either potash or soda, always produced a gain, which was too great to be attributed to common sour- ces of error. The investigation of the causes of this gain resulted in the discovery of lithia. • Annals of Philosophy (Mar. 1819.) p. 185. t Kroir. xiflnof, stony, because this alkaline base is furnished exclusively by the mineral kingdom; whereas potash and soda, are not. ,,-p. ALKALINE SALIFIABLE BASES. Book I. III. Lithia may be obtained from its carbonate by boil- Division H. inR a concentrated solution of the latter, along with slukej Method of lime: its carbonic acid is thereby transferred to the lime, obtaining it which becomes carbonate of lime. This latter carbonate is pUrC' then separated by the filter; and the remaining liquid, eva- porated to dryness in a silver crucible. The dry mass is pure lithia. IV. Lithia has a caustic alkaline taste; as strong as that of potash or soda. It acts powerfully on vegetable blues. It remains dry in the air, and dissolves with difficulty in wa- ter. These circumstances, as well as that of its forming t deliquescent salt with nitric acid, are sufficient to distin- guish it from potash or soda. V. Lithia is composed, in whole numbers, of Lithium 10—one atom. Oxygen 8—one atom. Its proper ties. i lomposi- tion of li- thia. Giving ing the weight of its atom.* 18 for the number represent- pure. SECTION V. OF LIME. Common name, Quicklime. Lime, how I» Lime may be obtained perfectly pure by the follow- obtained ing process: Dissolve oyster shells, reduced to powder, in acetic acid (distilled vinegar), and add to the solution ob- tained, a solution of carbonate of ammonia, as long as any precipitate appears: oyster shells are an impure carbonate of lime; and when they are dissolved in acetic acid, a pure acetate of lime is obtained; this acetate is decomposed by the carbonate of ammonia, and the precipitate which appears is a pure carbonate of lime. Expose the carbonate of lime, thus obtained, after being well washed and dried, for seve- ral hours to a white heat: the carbonic acid will be driven off; so that nothing will remain but the pure lime. II. Lime, in the large way, for the purposes of the arts, is obtained by exposing different species of limestone, which consist almost entirely of carbonate of lime, to a white heat: The carbonic acid is driven off, and the pure lime remains. This process is called burning lime. III. Lime abounds in all parts of the world, combined native"*'7 w^ different acids; but it occurs most abundantly in the form of carbonate of lime. Exists * Annates de Chimie et de Physique, tome x. p. 82, et seq. (Jan. 1819.) LIME. 161 IV. Lime it a white substance, very easily reduced to Chap. i. powder. It has a hot burning taste, and is capable of cor- Propertiea roding the animal fibre. It changes vegetable blues to a of ika*. green colour, which afterwards becomes yellow. When ex- posed to the open air, it gradually attracts moisture and carbonic acid. V. Lime is about two and one-third times as heavy as Spec. grav. water. Its fusing point is at a temperature, the highest 2'3- that can be raised. By subjecting it to the heat produced by the combustion of a jet of oxygen and hydrogen gases, Dr. Clarke succeeded in fusing it into a brilliant limpid glass. VI. Lime forms two combinations with water; one in a Lime forms solid form, called hydrate of lime; the other in the liquid *„,[^"oiu- form, called lime-water. The hydrate is formed, whenever tion. water is sprinkled on lime. The lime swells, becomes hot, and falls to powder. The water added exists in the solid state, combined with the lime. Lime-water will be noticed in the following paragraphs. 1. Lime-water may be prepared by throwing a quantity Lime-wa- of lime, in powder, into pure water. After the whole haster; ho* remained for some time, closed from the air, the water willprepare " have dissolved as much lime as it is capable of holding. The clear solution, after being decanted, is pure lime- water. 2. Lime-water is a transparent and colourless liquid, pos- itsproper- sessing an austere acrid taste. It changes vegetable blues to ties- green. When a perfectly saturated solution, it contains, not more than rfoth part of its weight of lime. 3. Lime-water appears to possess astringent properties. Its medical It is a very efficacious antacid and anti-emetic. The for- uses- mer property makes it suited to relieve certain affections of the stomach, attended with acidity and flatulence. Its anti- emetic powers are very conspicuous, when employed in the obstinate vomitings, attendant upon bilious and yellow fevers. VII. Lime suffers no change by mere exposure to the Lime may influence of oxygen gas. But it is, nevertheless, capable ofbe.suPer" combiniag with this supporter, as- has been already men-oxld,zed- tioned, under the head of calcium. This compound is called peroxide of calcium. It, however, remains yet to be proved, that oxidized lime is necessarily an oxide of calcium. VIII. Lime is capable of combining with chlorine. That It forms a this is the case, is proved by the result of a recent analysis ofc"' Mr. Tennant's bleachingsalt, usually called oxymuriate of lime, performed by Dr. Thomson. This chemist found it to consist of chloride of lime, mixed with uncombined lime. Chloride of lime, when exposed to heat, gives out oxygen, A - chloride. 162 ALKALINE SALIFIABLE BASES. Book I. and is converted into chloride of calcium, (dry muriate ol DiTi,ion "• lime).* Lime is capable of forming an iodide also. Phosphuret IX. Phosphuret of lime mav be obtained by the following of lime. process: Put at the bottom of' a glass tube, closed at one end, one part of phosphorus; and holding it horizontally, introduce into it, five parts of lime, in small lumps, so as to be within about two inches of the phosphorus. Put the tube across some burning coals, in such a manner, as that the lime may be brought to a red heat, while the phosphorus is comparatively cold. As soon as this is accomplished, move the tube along the coals, so as to expose the phosphorus to the heat; by which it will be converted into vapour, and, in this state, combine with the lime. During the combina- tion, the mass becomes of a glowing red heat, and a quantity of hydroguret of phosphorus (phosphuretted hydrogen) is emitted; which takes fire as soon as it comes in contact with the atmosphere. This phosphuret has a deep brown colour. It falls to pieces when exposed to the air. It is not soluble in water; but, when thrown into this liquid, it causes its decomposition, and hydroguret of phosphorus is evolved. It has not been analyzed. Sulphuret. X. Sulphuret of lime may be formed by heating its con» stituents together in a crucible. It has a reddish colour, which becomes greenish yellow, when exposed to the air or moistened with water. It has not been analyzed. Lime, with XI. Lime, combined with potash, forms the officinal potash, preparation, commonly called milder common caustic. caustie? 1. The Edinburgh college directs the following process for preparing this compound: Evaporate liquid potash (so- lution of potash) in a covered vessel, to about one-third. After being thus concentrated, add to it as much hydrate of lime (new slaked lime), as will bring it to the consistency of a pretty solid pap. The mass constitutes the caustic in question. It must be preserved in bottles, well closed from the air. Its uses to 2. This compound of lime with potash is the caustic usu- ally employed by surgeons for opening abscesses, for mak- ing issues, and, indeed, for most of the purposes, for which a caustic is required. 5°mprK'™- ^^' Lime, as the reader has already been informed, is an oxide of a peculiar metal, called calcium. It is composed of Calcium 21—one atom. Oxygen 8—one atom. Giving 29 for the number represent- ing its atom. the sur- geon. tion of lime. • Annals of Philosophy (Mar. 1819) p. 182. BARYTES. 163 XIII. Lime is of very great importance in the arts. It Chap. I. constitutes the principal ingredient in mortar. The best pro- Lime> the portions for this cement are principal Fine sand 3 parts. »£*£ Coarser sand 4 Lime, recently slaked, 1 Water, a sufficiency only to mix the ingredients. Mortar owes its property of becoming hard to the absorp- tion of carbonic acid, as well as to the solidification of a portion of water. By means of this property, as well as that of adhering strongly to brick or stone; it is capable of join- ing these substances together, as firmly as if they had been originally in one piece. The addition of a little clay to this cement, gives it the property of hardening under water. Certain lime stones contain a proportion of clay; and these, when burnt, furnish a very proper lime for water mortar. The best water mor- tar, however, is composed of lime, and puzzolano, a volca- nic sand found in Italy. XIV. Lime acts with considerable energy, as a corro-Is eorro, sive, upon the animal fibre. Its principal medical properties,Slve- when in solution, have already been mentioned, and need not be repeated here. SECTION VI. OF BARYTES.* I. Barytes may be obtained pure by the following pro- Barytes; cess: Expose a mixture, in a crucible, of eight parts in how 0°tain- powder, of ponderous spar (sulphate of barytes), and one ed pure' part of charcoal powder, for several hours to a red heat: by this treatment, the sulphate of barytes becomes converted into a sulphuret. Dissolve the sulphuret in water, and add nitric acid to the solution, as long as any precipitate appears: this acid combines with the barytes, and throws down the sulphur. Separate the sulphur by the filter; and evaporate the clear liquid, until it form crystals of nitrate of barytes. Expose the crystals, thus obtained, to a strong heat, gradu- ally increased: the nitric acid will be driven off, and the barytes left pure. II. Barytes occurs native, only in combination with sul- Howfoand. • From fiafif, heavy; on account of the unusual weight of the spar, from which it was first obtained 164 ALKALINE SALIFIABLE BASES Its proper- ties. Combines quid. Book l phuric or carbonic acid, forming sulphate or carbonate of Prv'si""Earvtes. 8 III. It was discovered by Scheele, in 1774. IV. Barytes is a porous substance, of a greyish-white colour. It is easily reduced to powder. It has an acrid, uri- nous taste, more caustic than that of lime. It possesses no perceptible smell. When exposed to the air, it attracts moisture, swells, evolves heat, and is converted into a hy- drate. If the exposure be long continued, it gradually at- tracts carbonic acid, and loses its causticity. It is capable of decomposing animal substances; but not with as much energy as potash or soda. V. Barytes is about four times as heavy as water. VI. Barytes combines with water in two forms: in the Manvdrateso^ ^orm» a3 a hydrate; and in the liquid form. The hy- and as a li- drate may be formed by slaking barytes; that is, by sprink- ling it with water, as long as this liquid is absorbed. The cold solution of barytes, when saturated, contains not more than one-twentieth of its weight of barytes; but the hot so- lution is capable of containing more than half its weight* The hot solution, as it cools, lets fall the barytes, in the form of transparent colourless crystals. These crystals, when exposed to the heat of boiling water, undergo the watery fusion, as it is called; that is, are dissolved in the water, which, at a lower temperature, existed, combined with them, in the solid form. If the heat be, afterwards, gradually increased, this water is driven off, and the barytes becomes dry. When the temperature arrives at the point of redness, the dry mass melts, and flows like oil. But whea barytes is obtained by decomposing the nitrate, it is per- fectly infusible in the most intense heat, that can be raised. This infusibility of barytes, as obtained from the nitrate, is supposed to be owing to the absence of water. VII. Barytes is capable of combining with oxygen. This compound has been already noticed as peroxide of barium. VIII. Barytes is capable of forming a chloride, as Dr. Thomson first ascertained. This chemist obtained it, by double decomposition, between a salt of barytes and chlo- ride of lime.* When, however, chlorine gas is passed over red hot barytes; the latter is decomposed, oxygen is evolved, and the resulting compound is chloride of barium. Phosphuret IX. Phosphuret of barytes may be formed by heating its of barytes. ingredients together, in a tube, closed at one end. A rapid combination takes place, and the phosphuret is formed. It is a brilliant, very fusible substance of a dark brown colour. Combines also with oxygen; and with chlorine. • Annals of Philosophy, (Mar. 1819) p. 185. STRONTIAN. \Q$ When thrown into water, it decomposes this liquid; the Chap. 1. hydrogen of which, combining with part of the phosphorus, ~- forms hydroguret of phosphorus, which inflames as soon as h comes in contact with the air; while the oxygen of the water, combining with the remaining phosphorus, forms phosphoric acid. X. Sulphuret of barytes may be formed, by melting its Sulphuret. constituents together in a crucible. A red heat is required for the fusion. It has a reddish-yellow colour, and no smell. When exposed to the air, or dissolved in water, it becomes decomposed; and hydrosulphuric acid (sulphuret- ted hydrogen) is evolved. XI. Barytes, as has been already mentioned, is an oxide Constitu- of a peculiar metal, which has been called barium. Its exact ™H° *' composition has not been ascertained by any direct experi- ments. XII. Barytes acts as a very violent poison on the human Barytes, a system. The effects of the chloride of barium have already P0,son- been noticed; and the cases, in which it has been used as a medicine, pointed out. It does not appear, however, that any compound has been used medicinally, in which barytes exists ready formed. XIII. In cases of poisoning by barytes, Orfila recom-itsantidote. mends the swallowing of large quantities of some sulphate; such as of sulphate of soda (Glauber's salt) or of sulphate of magnesia (Epsom salt). In this way, he proposes to form, in the stomach, a sulphate of barytes; which, from its great insolubility, may be considered as nearly inert. Afterwards, in case vomiting does not take place sponta- neously, he recommends that it should be encouraged by the usual methods.* SECTION VII. OF STRONTIAN.f I. Strontian may be obtained pure by the following Strontian; process: Dissolve the mineral called strontianite (carbonate how »htain- of strontian) in nitric acid: this acid will displace the car-edpure' bonic acid, and dissolve the strontian. Evaporate the nitric solution, until it form crystals of nitrate of strontian; and • Nancrede's abridgment of Orfila on Poisons, p. 170. t So called, from having been first found in the lead mine of Strotitian, in Ar grleshire, Scotland. 166 ALKALINE SALIFIABLE BASES. Book I. expose them to a red heat: the nitric acid will thereby be Division II. driven off, and the strontian left pure. How found. II* Strontian has been found, heretofore, only as a sul- phate, or a carbonate. It was discovered, in 1791, by Dr. Hope. Properties III. Strontian is a porous substance, of a greyish-white of Btwnti- colour, and possessing an acrid taste. It converts vegetable blues to green. It attracts moisture and carbonic acid. It is not poisonous; and acts but feebly upon animal substances. It tinges flame of a lively purple colour. It resembles ba- rytes in many respects; hut it may be distinguished from the latter, by the colour, with which it tinges flame; and by its salts, which are very different from those of barytes. IV. Strontian is between three and four times as heavy as water. Strontian V. Like the other alkaline salifiable bases, strontian is forms ahy. capable of existinjr in two states of combination with water. drate and a rr.T - . °. .. , . -it -i solution. I he hydrate may be formed, by sprinkling strontian with water. The strontian swells, becomes hot, and falls to powder, exactly as barytes does. The cold solution, when saturated, contains not more than-yf^rd part of its weight of strontian. Barytes is, therefore, much more soluble than strontian. The hot solution, however, contains a much larger quantity; and, as it cools, it lets fall the strontian i the form of crystals. Crystallized strontian is fusible at a red heat; but, when obtained from the nitrate, it is infusi- ble. The fusibility of the crystals is supposed to be owing to the presence of water. May b* so- VI. Thenard has recently ascertained, that strontian is peroxidized capable of being peroxidized. This combination has already been noticed, under the name of peroxide of strontium. Forms a VII. Chloride of strontian may be formed, by double ohlonde. decomposition, from a salt of strontian, and chloride of lime, as Dr. Thomson has lately ascertained.* When, however, chlorine gas is passed over strontian, at a red heat, the latter is decomposed, oxygen is evolved, and chloride of strontium is formed. Iodine combines with strontian, always without decomposition. Composi- VIII. Strontian, as the reader has already been inform- strontian. e<^»ls an oxide of a peculiar metal, which has been called strontium. Its exact composition has not, as yet, been as- certained by any direct experiment. IX. Strontian has no uses, either in medicine, or the arts. * Annals of Philosophy, (Mar. 1819) p. 185 MAGNESIA J67 Chap. I. SECTION VIII. OF MAGNESIA. (Usually called, Calcined Magnesia.) I. Magnesia may be obtained pure, by dissolving sul-Magnesia; phate of magnesia (Epsom salt) in water, and precipitating h^w^*itt" the solution by potash. The potash combines with the sul- pUr phuric acid, and remains in solution; while the magnesia, being insoluble, falls in the form of powder. II. Magnesia is obtained, by the apothecaries, by ex- How ob- posinc:, in a crucibie, carbonate of magnesia (common mag- tained for r • \ r i l i u * t'l i ■ ?j medical use. nesia) for several hours, to a red neat. Ine carbonic acid is thereby driven off, and the magnesia, left pure. From the nature of this process, magnesia is very frequently called calcined magnesia. III. Uncombined magnesia has been found at Hoboken, How found. in New-Jersey; but it is a very rare mineral. The stones, which contain magnesia, have certain external characters, by which they may be known. They have an unctuous feel, a greenish colour, a fibrous texture, and a silky lustre. The salts of magnesia, which occur native, are the sulphate, carbonate, and borate. IV. Magnesia was first introduced into medicine, at the Discovery. beginning of the last century. Its preparation was kept secret; but, notwithstanding, it was discovered, that it was present in the lixivium, remaining after the preparation of nitrate of potash (nitre). It was, however, confounded with lime, by most chemists, until Dr. Black published his Chemical experiments upon it, in 1755. The conclusions of this natu,!e» "^ chemist were confirmed, and extended, by Margraff, in by Black. 1759; and by Bergman, in 1775. V. Magnesia is a very soft, white, insoluble powder; its proper- possessing very little taste, and not the least smell. It*'"- converts delicate vegetable blues to green. When exposed to the air, it absorbs moisture, and carbonic acid; but this absorption goes on exceedingly slow. VI. Magnesia is about two and one-third times as heavy Spec grav. as water. It is infusible, when exposed to the strongest a3, heat, which can be raised in a furnace. But, by subjecting it to the heat, produced by the combustion of a stream of oxygen and hydrogen gases, Dr. Clarke succeeded, with great difficulty, in fusing it into a white enamel. VII. Magnesia is decomposed, at a red heat, by chlo- Is decom- rine; and its metallic radical magnesium becomes converted p??ed. ^ eh l Anne. 163 EARTHY SALIFIABLE BASKS. Book l into a chloride. It combines with iodine, however, without Division II. decomposition. Sulphuret VIII. Phosphuret of magnesia has never been formed. of magne- fiut tne sulphuret may be obtained by heating gently, in a crucible, one part of sulphur, and two parts of magnesia. It is in the form of a yellow powder, slightly agglutinating. When thrown into water, it causes the evolution of a small quantity of hydrosulphuric acid (sulphuretted hydrogen). Composi- IX. Magnesia, like all the other alkaline salifiable bases, tionofmag- js a metallic oxide. But the proportion, in which its con- nesia. . . , * r. ,, ^ . , stituents unite, has not been experimentally ascertained. Its medical X. Magnesia is a very valuable medicine. Its effects are uses, those of an antacid and gentle aperient. For removing acidity of the stomach, it acts more promptly, and with less inconvenience, than carbonate of magnesia (common magnesia). Theclassof Having finished the account of the alkaline salifiable hfi^bie^baT bases; it is now proper to inform the reader, what proper- ses, charac-ties, possessed in common by these bodies, constitute the tenzed. basis of their arrangement into one class. The usual divi- sion of the salifiable bases, is into alkalies, alkaline earths, earths, and metallic oxides. Now, instead of the two first of these classes, the class of alkaline salifiable bases hat been substituted. Barytes and lime do not stand well, sepa- rated from potash and soda; for they possess the distinctive properties of the latter, although in a less degree. The same remark, with very little variation, will apply to strontian. Magnesia appears to be on the line, between alkaline and earthy salifiable bases; but, having the power of changing some vegetable blues to green, it has been associated with the former. So that the common property, possessed by the alkaline salifiable bases, is that of changing vegetable blues to green. Besides this property, these bodies have, nearly all, an acrid taste, and act as a caustic upon the skin. CLASS II. EARTHY SALIFIABLE BASES. Earthy sah- The earthy salifiable bases are the following bodies: fiabie bases, i. Yttria. 3. Alumina. 5. Thorina. 2. Glucina. 4. Zirconia. 6. Silica. They will be described, in the order in which they have been enumerated, in the following sections. enumera ted. TTTRIA. 169 Chap. I. SECTION I. OF YTTRIA.# I. Yttria may be obtained from the mineral, called Yttria; gadolinite, which is a compound of this salifiable base and ^lure*"1* silica, combined with the protoxides of cerium and of iron, by the following process: Digest the mineral in aqua regia, as long as any thing is dissolved; and evaporate the solu- tion obtained, nearly to dryness. Then filter it, and dilute it with a considerable quantity of water: by these measures, the silica is separated. Evaporate the liquid, as it now stands, to dryness; heat the dry mass to redness, and afterwards redissolve it in water, and filter the solution formed. To this second solution, add liquid ammonia: a powder immediately falls, which is composed of oxide of cerium, and yttria. Dissolve this precipitate, after having been heated to redness, in nitric acid; and evaporate the solution to dryness, in order to remove any excess of the acid. Dissolve the dry mass in 150 times its weight of water, and add crystals of sulphate of potash to the so- lution: after the hpse of a few hours, as the crystals gra- dually dissolve, the oxide of cerium precipitates, in the form of a white powder. Separate the oxide of cerium, by the filter; and add, to the clear solution, liquid ammonia. This addition throws down a powder; which, after being separated, washed, and heated to redness, is pure yttria. II. Besides in gadolinite, yttria has been found, in the Minerals, mineral called yttrocerite, associated with lime, thorina, ?hi.chaf: oxide of cerium, and hydrofluoric (fluoric) acid; and in °" ytt"a' yttrotintalite, in combination with columbium. III. Yttria was discovered, in 1794, by Gadolin. IV. Yttria is in the form of a fine, white insoluble pow- Properties der, destitute of taste, or smell. It produces no changeofjttria- upon vegetable blues. It is insoluble in alcohol, or in pot- ash or soda; but it dissolves in the carbonates of these alkaline bases. V. It is nearly five times as heavy as water. It is the Spec. grav. heaviest of the earthy salifiable bases. 4'84* VI. Yttria, as has already been mentioned, is a com-Composi- pound of a peculiar metal, which has been called yttrium,tion- and oxygen. But the exact proportion, in which its consti- tuents unite, has not been ascertained. • From Ytterbv, the name of a quarry in Sweden; where the mineral, from whioli yttria was first obtained, was found. "merai, irom Y 17Q EARTHY SALIFIABLE BASE^ BookL Division II. SECTION II. OF GLUCINA.* Glucina; I. Glucina may be obtained from the beryl or the edpitfe.ai!l'emer»W, in which it is combined, principally, with silica and alumina, by the following process: Reduce the stone to powder, and fuse it with three times its weight of potash. After the mass has been diluted with water, dissolve it in hydrochloric (muriatic) acid, and evaporate the solution formed to dryness. Treat the dry mass with a large quan- tity of water, and throw the whole upon a filter: the glu- cina, and alumina, in the state of solution in hydrochloric acid, pass through; while the silica, which constitutes more than half the stone, remains behind, retained by the filter. To the clear solution, thus obtained, add carbonate of pot- ash (salt of tartar), as long as this salt produces any preci- pitate: this reagent will throw down the glucina and alu- mina, in a state of mixture. Dissolve the precipitate thui obtained, after being washed, in sulphuric acid; add to the solution formed, sulphate of potash; and then evaporate it to a proper consistency, and let it stand to crystallize: crystals of alum will form, which will contain the whole of the alumina. Separate the crystals from the solution; and, to the remaining liquid, add a solution of carbonate of am- monia, in excess. Then filter the whole, and boil it for some time. A powder gradually falls, which consists of glucina. In what II. Glucina has been found, heretofore, only in the beryl, minerals and tne emerald. The beryl is found, particularly, in Siberia; the emerald comes chiefly from Peru. III. Glucina was discovered, in 1798, by Vauquelin. Its proper- IV. Glucina is in the form of a soft, light, white powder, ues* destitute of taste, or smell. It is insoluble in water, or al- cohol; but dissolves in solutions of potash or soda. SP«C- §Fav- V. It is very nearly three times as heavy as water. Composi- VI. Glucina is an oxide of a peculiar metal, which has tion. been named glucinum. Its exact composition, however, is not known. * From yKvxvf, sweet; on account of the sweet taste of the salts, which ■< forms. ALUMINA 171 «HAP. I. SECTION III. OF ALUMINA.' Common names, Argil.—Pure Clay. I. Alumina may be obtained by the following process: Alumina; Dissolve alum, which is a compound, principally, of sul- Jj pU°rbetain" phuric acid and alumina, in water; and add to the solution, liquid ammonia, as long as any precipitate appears: the greater part of the sulphuric acid, present in the alum, combines with the ammonia, and remains in solution; while a small remainder of it falls in combination with the alumina. Wash the precipitate, thus obtained, in a large quantity of water; and then heat it strongly in a platinum crucible: the small portion of sulphuric acid present is thereby driven off, and the alumina, obtained pure. II. Alumina exists very abundantly native. It constitutes Exists in a large amount in all clays, and exists in a great number of c,ays- minerals. III. The discovery of alumina, in a pure state, is very Account of much connected with the investigations, made by chemists, ^jl1800' into the nature of alum. This latter substance was early known to contain sulphuric acid, and an earth. This earth was supposed to be lime, by Stahl and Neumann. This supposition was proved to be incorrect, in 1728, by Geoffroy, junior; who identified it with the earth, which exists so abundantly in clay. In 1754, Margraff confirmed the conclusions of Geoffroy, obtained the earth in tolerable purity, and described its peculiar properties. Since that time, its nature has been fully investigated by Macquer, Bergman, Scheele, and Saussure, junior. IV. Alumina is a fine white powder, destitute of taste Properties or smell. It adheres strongly, when applied to tne tongue, of alumina. It is insoluble in water; but dissolves readily in solutions of potash or of soda. When exposed to heat, it suffers con- traction. At low temperatures, this contractiori is probably owing to the dissipation of moisture; bat, at high ones, it takes place also, without losing any sensible weight. In the latter case, the increase of density may be accounted for by supposing a more intimate union of the partieles of the alumina. V. Alumina is about twice as heavy as water. When • From alttmen, the Latin for alum, the substance from which it was first ob- tained in a state of purity; se called by Morveau. 172 EARTHY SALIFIABLE BASES. Hydrate of alumina. Book I. exposed to the violent heat, produced by the combustion of msion II. charcoal, by means of a stream of oxygen gas; it undergoes the commencement of fusion, and is converted into a very hard, semi-transparent enamel. VI. Alumina combines with water, in the form of a hydrate. It is always in this state, when precipitated from solution in acids. In the state of dry hydrate, it is capable of absorbing, and retaining, about two and a half times its bulk of water. It exists, in the state of hydrate, in the mi- neral called wavellite. VII. Alumina, in combination with peroxide of iron, forms the yellow paint, called yellow ochre. VIII. When alumina is heated, with either potash or soda; a loose mass is formed, destitute of transparency. When dissolved in solutions of these alkaline bases, it may be precipitated from them, by means of an acid. Alumina is usually obtained, in a state of purity, by this method. IX. Alumina is a compound, as the reader has already been informed, of oxygen, and a peculiar metal, which has been named aluminum. But the proportion, in which its constituents are combined, has not been correctly ascer- tained. X. Alumina constitutes the chief material in China and stone-ware of all kinds. In dyeing, and in calico-printing, it is of indispensable utility. Composi- tion of alu mina. SECTION IV. OF ZIRCONIA.* Zirconia; I. Zirconia may be obtained from the zircon, or the en this place view of all the salifiable bases. Of the metals, which, by their combinations with oxygen,The saiifia- give rise to the formation of salifiable bases of the third {*„•„ £sess of class, seven appear to be capable of forming but one oxide; arevery va- namely, zinc, bismuth, silver,palladium, osmium, antimo- jjjj™.fi ny" and tellurium: three are capable of forming three ox-blepower* ides; namely, manganese, rhodium and titanium; and all • In this statement, the word oxide is used in the strict sense. Of course anti- monious acid and antimonic acid are not included under its meaning z 178 SALIFIABLE BASES, NOT ALKALINE OR EARTHY. Book I. the rest, but two oxides. The oxides of zinc, bismuth and livisi0n II- silver have the salifiable property in a very perfect degree. As far as the oxide of palladium is known, it does not seem to possess the salifiable power in any remarkable degree. No experiments have proved that oxide of osmium is not salifiable; and yet it is not known to enter into the compo- sition of any salt: in strict propriety it ought not to stand here. Oxide of antimony enjoys the property of neutraliz- ing acids, only in a slight degree; and requires almost always, in its saline combinations, to be associated with a second base. Oxide of tellurium possesses the properties of an acid, more than those of a salifiable base; it enjoys but a very imperfect neutralizing power. Of the metals, which combine, in three proportions with oxygen, the middle oxides are not known to be salifiable. The remaining oxides, included under this class of sa- lifiable bases, are very various in their salifiable property. The protoxides and peroxides of iron, of nickel, of manga- nese, of cerium, of uranium, of tin, of mercury, of gold, of platinum, and of titanium, are both salifiable; but not in equal degrees for all these metals. Of tin and mercury, both the oxides possess the salifiable property in nearly equal degree; but the oxides of the former metal, have little affinity for acids. Of all the other metals, just enumerated, except gold and platinum, the protoxides combine with acids, with the greatest facility. With regard to the oxides of gold, there is some doubt whether the protoxide is sali- fiable; at least, this oxide enters into but one known salt. Of the oxides of platinum, the peroxide seems to be the most readily salifiable. Of some of the metals which have been enumerated, ^s furnishing the salifiable bases of this class, the protoxides only are salifiable. This is the case with cobalt and lead; for the peroxides of these metals do not enter into the composition of any salt. On the other hand, the peroxides of copper and rhodium, appear alone to be salifiable; while their protoxides do not possess this pro- perty. With respect to iridium, too little is known, to ena- ble a decision to be made, with regard to the relative sali- fiable power of its oxides. With this general account of the salifiable bases of the third class; the consideration of the whole of the salifiable bases, is completed. Supposing that all the oxides of the metals, which furnish the third class of salifiable bases, SALIFIABLE BASES, NOT ALKALINE OR EARTHY. 179 were really known to enter into the composition of some Chap. I. salt; then the total number of salifiable bases of all kinds ~ would be 54: namely, 8 Alkaline salifiable bases; 6 Earthy salifiable bases; and 40 Salifiable bases having neither alkaline, nor earthy properties. Upon taking a general view of the salifiable bases, it is very readily perceived that these bodies, in chemical nature, bear a very exact analogy to each other; being all, with the exception of ammonia, metallic oxides. They are all solids, the same substance excepted. A comparative view of their properties may be seen in the following tables. TABLE OF THE ALKALINE SALIFIABLE BASES. Names. Synonymes. Discoverer, and time of discovery. State as to aggre-gation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. Specific Gravity. Melting Point. Composition. Weight of an atom of each. Compared with air. Compared with water. 1. Ammonia. Volatile Alkali. Hartshorn. First obtained pure by Dr. Priestley. Gaseous. Colourless. Exeeed-ingly pungent. Acrid and hot. Water takes up 670 times its bulk. 0-590. Hydrogen 3 three atoms. Azote 14 one atom. 17 2. Potash. Pure Kali. Caustic Vegeta-ble Alkali. Solid. White. Like that produced by slaking lime. Extremely acrid. Water dissolves twice its weight- Deliquescent. 1-70. Fusible. Potassium 40 one atom. Oxygen 8 one atom. 48 i. Soda. Causlie Fossil Alkali. Caustic Mineral Alkali. Solid. Greyish-white. Like that produced by slaking lime. Extremely acrid. Readily soluble. Absorbs mois-ture and car-bonic acid, and falls to powder. 1-33. Fusible. Sodium 24 one atom. Oxygen 8 one atom. 32 4. Lithia. Arfwedson; 1818. Solid. . Caustic and alkaline. Difficultly solu-ble. Remains dry. Lithium 10 one atom. Oxygen 8 18 one atom. <■ 5. Lime. Quicklime. Known from the earliest ages. Solid. White. Hot and burning. Dissolves in 759 times its weight of water. Attracts mois-ture and car-bonic acid. 2-3. Very high. Calcium 21 one atom. Oxygen 8 one atom. 29 6. Barytes. Scheelej 1774. Porous solid. Greyish-white. Inodorous. Acrid and urinous. Cold water dis-solves l-20th of its weight; hot water, more than half its weight. Attracts mois-ture, swells, and becomes hot. 4* At a red heat, when a hydrate. Barium. Oxygen. 7. Strontian. Hope; 1791. Porous solid. Greyish-white. Acrid. Dissolves in 162 times its weight of water. Attracts mois-ture and car-bonic acid. Between 3 and 4. At a red heat, when a hydrate. Strontium-Oxygen. 8. Magnesia. Calcined Mag-nesia. Distinguished from lime, by Black. Soft powder. White. Inodorous. Nearly tasteless. Insoluble. Attracts mois-ture and car-bonic acid very slowly. 2-3. Exceed-ingly high- Magnesium. Oxygen. TABLE OF THE EARTHY SALIFIABLE BASES. Names. Discoverer, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. Specific Gravity. Melting Point. Constituents. Weight of an atom of each. 1 Yttria. Gadolin; 1794. Fine powder. White. Inodorous. Tasteless. Insoluble. 4-842. Yttrium. Oxygfen. 2. Glucina. Vauquelin; 1798. Soft light pow-der. White. iuoJPk. Tasteless. Insoluble. 2-976. Glucinum. Oxygen. 3. Alumina. Margraff; 1754. Fine powder. White. Inodorous. Tasteless. Insoluble. 2- Undergoes the commence-ment of fusion, in a very in-tense heat. Aluminum. Oxygen. 4. Zirconia. Klaproth; 1789. Fine powder. White. Inodorous. Tasteless. Insoluble. 4-+ Softened by the heat of a good forge. Zirconium. Oxygfen. 5. Tborina. Berzelius; 1815. Whenjust separa-ted, a gelatinous and semi-trans-parent mass. White. Inodorous. Absorbs carbonic acid. Very infusible. Presumed to be a peculiar metal, and oxygen. 6. Silica. Peculiar nature, made out by Bergman and Scheele. Harsh powder. White. Inodorous. Tasteless. Insoluble, e\e<|.t when newly preci-pitated. 2-66. Exceedingly infusible. Silicum 8 one atom. Oxygen 8 one atom. 10 182 TABLE OF THE SALIFIABLE BASES, HAVING NEITHER ALKALINE*N0R EARTHT PROPERTIES. NAMES. COLOUR. COMPOSITION. Weight of an atom of each. 1. Protoxide of Iron. Black. I-on 28—one atom. Oxygen 8—one atom. 36 2. Peroxide of Iron. Red. j \\on 56_two atoms. 1 8() | Oxygen 24—three atoms. | 3. Protoxide of Nickel. Ash-grey- Nickel 27—one atom. Oxygen 8—one atom. 35 4. Peroxide of Nickel. Black. Nickel 54—two atoms. Oxygen 24—thie atoms. 78 5. Protoxide of Cobalt. Blue. Cobalt 29—one atom I „_ Oxygen 8—one atom. 1 6. Peroxide of Cobalt* ni . J Cobalt 58—two atoms. BlacK- 1 Oxvgen 21— 1. _. 7 Protoxide of Manganese. r..- • Manganese 28—one atom. Olive-green. 1 ,k & „ ,.„. & | Oxygen 8—one atom. 1 36 8. Deutoxide of Manganese f R. . 1 Manganese 56—two atoms. BiacK. | ()xvgeri 24—three atoms. 80 9. Peroxide of Manganese- Dark steel-grey. Manganese 28—one atom. Oxygen 16—two atoms. 1 44 10. Protoxide of Cerium. White. ----- 11. Peroxide of Cerium. Reddish-brown. 12. Protoxide of Uranium. Greyish-black. Uranium J§§—one atom. Oxygen 4K—one atom. 133 13. Peroxide of Uranium. Yellow. Uranium 250—two atoms. j __. Oxygen 24—three atoms. 14. Oxide of Zinc. White. Zinc 33—one atom. Oxygen 8—one atom. 41 15. Protoxide of Lead. Yellow. Lead 10-i—one atom. Oxygen S—one aiom. 112 16. Peroxide of Lead.* Flea-brown. Lead 104—one atom. J .^ Oxygen 16—two atoms. | 17. Protoxide of Tin. Dark-grey. Tin 59—one atom. Oxygen _, 8—one atom. 67 18. Peroxide of Tin. Yellow. Tin 59—one atom. Oxygen 16—two atoms. 75 19- Protoxide of Copper.* Yellow. Copper 6i—one atom. Oxygen 8—one atom. 72 20 Peroxide of Copper. } Black. Copper 64—one atom. Oxygen 16—two atoms. 80 21. Oxide of Bismuth. Yellow. Bismuth 71—one atom. Oxytren 8—one atom. 79 22. Protoxide of Merccury. Black. Mercury 20O—one atom. Oxygen 8—one atom. 208 23- Peroxide of Mercury. Bright scarlet. Mercury 200—one atom. Oxjgen 16—two atoms. 216 * The oxides marked thus * do no( possess the salifiable property. f This oxide is not known to enter, as a constituent, into any salt 183 TABLE CONCLUDED. NAMES. COLOUR. COMPOSITION. Weight of an atom of each. 24. Oxide of Silver. Dai-k olive-brow u. Silver 110—one atom. Oxygen 8—one atom. 118 25 > *i otnxide of Gold.* Green. j Reddish~ brown. (■ M 200—one atom. Oxygen 8—one atom. 208 20. Peroxide of liold. 1 Gold 200—one atom. | Oxygen 24—three atoms. 224 2' I'rotoxide of Platinum. Deep-black. 2* IVroxide of Plsuinum. Dark-brown. 29. ' Ixide of Palladium. 3d Protoxide ot Rhodium.* Chesnut-brown. Palladium 56—one atom. J -. Oxygen 8—one atom. | Black. 1 1 31 Deutoxide of Rhodium.* Brown. 32. Peroxide ot Rhodium. 1 Red. 33. Protoxide of Iridium. 34. Peroxide of Iridium. 35. Oxide of Osmium.* 1 Semi-trans-| parent. 36. Protoxide of Titanium. Blue, or purple. 37. Deutoxide of Titanium.* Red. 38. Peroxide of Titanium. White. 39. Oxide of Antimony. Dirty white. 40. Oxide of Tellurium.$ White. Tellurium 32—one atom. Oxygen 8—one atom. 40 * It is doubtful whether these oxides are salifiable. * These oxid-s an- not known to be salifiable. § This oxide is salifiable only in an imperfect degree. 184 Book I. Division II. ACIDS CHAPTER II. OF ACIDS. Acids, ar- The acids will be arranged in five clases; each class em- fiveScia»ses. bracing acids, characterized as follows: Class I. Acids, whose bases form acid compounds with oxygen or hydrogen indifferently. Class II. Acids, whose bases form acid compounds with oxygen only. Class III. Acids, whose bases form acid compounds with hydrogen only. Class IV. Acids of irregular constitution. Class V. Acids, in which oxygen and hydrogen are both present. CLASS I. ACIDS, WHOSE BASES FORM ACID COMPOUNDS WITH OXYGEN OR HYDROGEN INDIFFERENTLY. Acidsofthe Acids belonging to this class are the following: first class 1. Chloric acid. 6. Sulphuric acid. 11. Selenic acid enumera- 2. Oxychloric acid. 7. Sulphurous acid. tei 3. Hydrochloric acid. 8. Hyposulphurousactd. 4. Iodic acid. 9. Hydrosulphuric acid. 5. Hydriodic acid. 10. Hydrosulphurous acid These acids will be described in the following sections 12. Hydroselenic acid. 13. Telluric acid. 14. Hydrotelluric acid. Chlorine forms two acids by combining with oxygen; namely, chloric acid and oxychloric acid. These acids will be noticed in the two following sections. Chloric acid; how obtained. SECTION I. OF CHLORIC ACID. Former chemical name, Hyperoxymuriatic Acid. I. Chloric acid may be obtained by adding diluted sul- phuric acid to a solution of chlorate of barytes, as long as any precipitate should appear: the sulphuric acid combines with the barytes, so as to form an insoluble sulphate of ba- rytes. Remove the insoluble sulphate by the filter; and the remaining liquid will be a solution of chloric acid in water. OXYCHLORIC ACID. 185 II. Berthollet first obtained chloric acid, without being Chap. II. await- oi its nature, in a state of combination with potash, Account of by p.issmg a current of chlorine gas, through a solution of its discove- carbonatc of potash. He suspected that the substance, which1"7 became combined with the potash, was different from chlo- rine (then called oxymuriatic acid); although the manner in which the experiment was conducted, naturally led to a contrary belief. Chenevix afterwards confirmed thesuspition ot Berthollet, that the substance which became united with the potash, was not chlorine; and was right in the compo- sition which he assigned to it; if the circumstance be ex- cepted, that he adopted the then prevailing opinion with regard to chlorine, that it was a compound of oxygen and hydrochloric (muriatic) acid. Gay-Lussac, however, first obtained the acid in a separate state, in 1814, by the pro- cess just described. HI. Chloric acid is a colourless liquid, destitute of smell, Its proper- unless when concentrated; and possessing a very acid taste.ties" It reddens vegetable blues; but after its action has conti- nued for several days, it destroys them entirely. It is not altered by exposure to light. When exposed to a gentle heat, it mav be concentrated, so as to assume an oily consistency; but when subjected to a strong heat, part of it becomes de- composed into oxvgen and chlorine; while the remainder distils over without alteration- It does not possess the pro- perty of precipitating metals from their solutions. It dis- solves zinc rapidly, with the emission of oxygen gas; but it acts feebly upon mercury. Its specific gravity has not been ascerta ned. It combines with* jsalifiable bases, and forms a genus of salts called chlorates, formerly called, hy- peroxymuriates. IV. Chloric acid is composed of Composi- Chlorine 36—one atom. tf°n Oxygen 40—five atoms. **■ Giving 76 for the number represent- ing its atom. SECTION II. OF OXYCHLORIC ACID. I. Oxychloric acid may be obtained by the following Oxychiori* process: mix 200 grains of strong sulphuric acid with 50*^n^w grains of chlorate of potash; so as that the whole may form a yellow coloured mass: a violent chemical action will take place between the constituents of this mixture. As soon as 2 A 186 ACIDS. Book I. this action is over; expose the mass to heat, until its yellow Division II. coiour disappear: by this exposure to heat, the mass be- comes a combination of the acid under description, with potash; rendered impure, however, by admixture of bisul- phate of potash. Dissolve the mass in water, and let it stand to crystallize: all the bisulphate of potash will sepa- rate in crystals; so that, after these are removed, what re- mains will be a pure solution of oxychlorate of potash. Distil this solution, in a retort, mixed with its own weight of sulphuric acid, at a heat of 280°: the oxychlorate of pot- ash becomes decomposed; sulphate of potash is formed, and oxychloric acid distils over. Discovery. II. Oxychloric acid was lately discovered by Count Von Stadion; by whom it was obtained by the process just des- cribed. its proper- HI. Oxychloric acid has been but very imperfectly exa- nes not mined. None of its properties hav e, as yet, been ascertained. The only salt, into which it is known to enter as a consti- tuent, is oxychlorate of potash. Composi- IV. Oxychloric acid is composed of Chlorine 36—one atom. Oxygen 56—seven atoms. Giving 92 for the number representing its atom.* tion. Chlorine forms but one acid with hydrogen; namely, hydro- chloric acid. This acid will be described in the follow- ing section. SECTION III. OF HYDROCHLORIC ACID. Usual chemical name, Muriatic Acid. Old names, Marine Acid.—Spirit of Sea Salt. Hydrochlo- I. Hydrochloric acid may be obtained by distilling, in hCwC'bt' a retort' at l^e ^eat °f a lamP» a mixture of equal parts of ed., chloride of sodium (common salt) and liquid sulphuric acid. As soon as the mixture is made, a violent effervescence en- sues. The gas which is extricated is at first mixed with * Dr. Thomson calls this acid perchloric acid. But I have not followed him in this particular; because his prefix per may lead to ambiguity. Should chrorie acid prove, hereafter, to be capable of combining with a peroxidiaed base; the salt which would be formed, would be a perchlorate. Now this is the very name, which would properly belong to a salt, formed by Dr. Thomson's perchloric acid. HYDROCHLORIC ACID. 187 atmospheric air, and should be allowed to escape. After the Cahp. n. lapse of a few minutes, the pure gaseous product may be collected in glass jars over mercury: it consists of hydro- chloric acid. II. The formation of hydrochloric acid, by the above Process ex process, is the result of a very complicated play of chemi- P,ained cal affinities. The acid, ready formed, is not present in any of tiie constituents employed; but is produced by a combi- nation of its ingredients, which takes place during the pro- cess. The chloride of sodium becomes decomposed, and, at the same time, a portion of water, with which liquid sul- phuric acid is always mixed. The sodium of the chloride, after being first converted into soda, by oxygen furnished bv the decomposition of the water, combines with the sul- phuric acid, so as to form sulphate of soda; while the chlo- rine unites with the corresponding hydrogen of the same liquid, so as to form hydrochloric acid. III. The nature of hydrochloric acid remained a long Account of time enveloped in uncertainty. It was generally considered Jfee8,dwlSch to be a compound; yet no one was able to demonstrate its led to as- ronstituents. certaining constituents. ..... tbe nature The first step, in the investigation, which terminated in 0f hydro- the discovery of the true nature of hydrochloric acid, was chloric acid-. made by Gay-Lussac and Davy. These chemists ascertain- ed, that the gas, which had been previously called oxymu- riatic acid, under the influence of the belief, that it was a compound of muriatic (hydrochloric) acid and oxygen, had never been decomposed; and that neither its reputed con- stituents, nor any other, could be demonstrated to exist in it. Hence, therefore, it is as yet an undecompounded body. In consequence of this discovery, it became necessary to change its name; and, accordingly, Sir H. Davy substituted, for oxymuriatic acid, the name of chlorine, as has been al- ready mentioned. The experiment, which was supposed to demonstrate the compound nature of oxymuriatic acid; and that oxygen and muriatic acid were its constituents, was first made by Ber- thollet. This chemist exposed a saturated solution of oxy- muriatic acid to the influence of the light of the sun, for several days; so arranged as to enable him to collect the gaseous products. At the end of this time, the gas which had been extricated, proved to be oxygen; and the oxymu- riatic solution was converted into a solution of muriatic acid. The more obvious conclusions to be drawn from this experiment are, that the oxymuriatic acid had been decom- posed; that the oxygen, which appeared, was derived from it; and that oxymuriatic acid, deprived of oxygen, became muriatic acid. 188 ACIDS. Book I. The evidence, therefore, that oxymuriatic acid was a iivisionll. Cf)mp0nnd of oxygen and muriatic acid, appeartd to be de- rived from analysis; and its composition was supposed to be perfectly settled. This continued to be the prevailing opinion, until 1809; when Gay-Lussac and Thenard pub- lished some experiments, going to demonstrate that oxygen could not be separated from oxymuriatic acid. In 1810, Sir H. Davy published two papers on the same subject; detailing experiments, which went to prove, that oxymu- riatic acid had never been decomposed. This chemist subjected it to a number of trials, with a view, if possible, to detect oxygen in it; but all these trials failed. He found that none of the compounds of oxymuriatic acid with inflammable bodies or metals, could be made to yield a particle of oxygen; and when the oxymuriatic acid gas was subjected to the action of charcoal, intensely ignited in it, or to the strongest powers of electricity, it underwent no change. The experiments and observations of these dis- tinguished chemists were well calculated to throw an air of doubt upon the reality of the decomposition of oxymu- riatic acid by Berthollet. Some time before these new opinions, respecting oxy- muriatic acid, were promulgated; it had been observed by Gay-Lussac and Thenard, that, when equal volumes of oxymuriatic acid and hydrogen are exposed to the action of the sun's rays, an explosion takes place; the gases combine, and the product is an equal volume of muriatic acid.* The conclusion, which these chemists first drew from this experiment, was, that muriatic acid gas, as usually obtained, is a compound of dry muriatic acid and water; and that the hydrogen, which disappears, unites with the oxygen of the oxymuriatic acid (adhering to the prevailing opinion respecting its composition), and forms water; while the dry muriatic acid, furnished by the decom- position of the oxymuriatic acid, combining with this water, gives rise to the formation of muriatic acid in its usual state. The merit of first drawing the proper conclusion from the experiment, above detailed, belongs to Sir H. Davy. This chemist admitted no explanation of it, which required the improper assumption, that oxygen is a constituent in oxvmuriatic acid (his chlorine); more especially as the ex- periments, which seemed to indicate such a constituent in * This experiment was performed about the same time by Mr. Dalton, as Dr. Thomson informs us, before the former chemist had any knowledge of what had been done by Gay-Lussac and Thenard. HYDROCHLORIC ACID. 189 it, were liable to so obvious a source of fallacy, by the Chap.il presence of water, or other substances which contain oxy- ~" gen, as to destroy all confidence in them. He, accordingly, insisted, that the only inference, which could be properly drawn from the experiment, above given, is, that oxymu- riatic acid, as an elementary substance, by combining with hydrogen, forms muriatic acid. Adopting this explanation of the formation of muriatic acid, in the above experiment; the nature of the fallacy in the experiment, by which Berthollet was supposed to indi- cate the constituents of oxymuriatic acid, is sufficiently manifest. The oxygen, which made its appearance in this experiment, owed its formation to the decomposition of water; the corresponding hydrogen of the same liquid, be- ing employed in the production of the muriatic acid, by combining with the oxymuriatic acid. If the source of the oxygen, in Berthollet's experiment, be the decomposition of water, as is here contended, and not the oxymuriatic acid; then it ought to be found, that the quantity of hydrogen necessary, by the new theory, to convert any portion of oxymuriatic acid into muriatic acid, is exactly the proper amount, to convert, into water, all the oxygen, which is alleged to be derived from the decompo- sition of an equal portion of this substance by the old theory. Now this is found to be the fact precisely; for the hydro- gen necessary to convert a given portion of oxymuriatic acid into muriatic acid, by the new doctrine, bears the same proportion to the oxygen, which, by the old doctrine, must be separated from it, during the same conversion; as these substances do, to each other, when they unite to form water. The doctrine of Sir H. Davy, that muriatic acid is a compound of oxymuriatic acid (chlorine) and hydrogen, at first, had many able opponents; who were disposed to coin- cide in opinion with Gay-Lussac and Thenard, as to its nature. These chemists, however, very soon embraced the new doctrine. Notwithstanding, the new views were still opposed by a number of chemists; but, in the progress of the controversy, new facts were elicited, which confirmed more and more the doctrine of Davy; and, since the recent discovery of iodine; which, among other striking analogies to oxymuriatic acid, possesses the property of forming an acid with hydrogen; the new explanations are almost uni- versally admitted* It may conduce to give a clearer idea of the new views and explanations, which have been introduced into che- mistry, by the discoveries, connected with muriatic acid, to / 190 ACIDS. Book I. exhibit them in comparison with those formerly held, in the E^LiL following manner. FORMER opinions. Compari- u Oxymuriatic acid is a son be- compound of muriatic acid tween the an(J oxygen. old and new * » opinions respecting oxymuriatic acid, and muriatic acid. 2. Muriatic acid has never been resolved into simpler constituents: it is, therefore, a simple body. 3. When a solution of oxy- muriatic acid, in water, is exposed to the light of the sun; the oxymuriatic acid disappears, and the only pro- ducts are muriatic acid and oxygen. These products must, therefore, be the constituents of oxymuriatic acid; PRESENT OPINIONS. 1. Neither muriatic acid, oxygen, nor any other sub- stance, has been detected in oxymuriatic acid: it is, there- fore, as yet, an undecom- pounded body. 2. Muriatic acid is a com- pound of oxymuriatic acid and hydrogen. 3. The products obtained, by exposing a solution of oxymuriatic acid, in water, to the influence of the light of the sun, owe their forma- tion to the decomposition of water. The muriatic acid is formed, in consequence of the combination of the hy- drogen of this liquid, with the oxymuriatic acid. The oxygen, appears, as the cor- responding constituent of the decomposed water. The propriety of appropriating a new name to the sub- stance, which had been previously called oxymuriatic acid, is sufficiently obvious. Its old name had a tendency to keep up an erroneous estimation of its constituents, calculated to embarrass the student of chemistry. The name of chlorine, which has been given to it by Sir H. Davy, has always been employed in this work. Hydrochloric acid has been substituted also for muriatic acid, in conformity with the usage of Gay-Lussac; the former name being preferred, because it suggests the constituents of this acid. But as the name, muriatic acid, is much more familiar, to most chemical readers, than that of hydrochloric acid; the former has, in most cases, been inserted, in parentheses, to explain the latter. Properties ^V. Hydrochloric acid possesses the following proper- of hydro- ties. It is a gaseous fluid, invisible like common air. It possesses a very sour taste, and peculiar smell. It reddens vegetable blues. When it comes in contact with the at- chloric acid. HYDROCHLORIC ACID. 191 mosphere, it appears in the form of white vapour, owing to Chap. II. its combination with moisture. V. This acid is about one and one-third times as heavy Spec. grar. , • • 12847. as atmospheric air. VI. It is incapable of supporting combustion. It is, strictly speaking, unrespirable: when the attempt is made to draw ir into the lungs, the glottis closes spasmodically. VII. Hvdrochloric acid is capable of combining with a Hydmchlo- numbt-r of dosts of oxvgen. This curious fact has lately ™£«J been ascertained by Thenard. This chemist moistened a combined portion of peroxide of barium with water; and then dissolv- ™Jj£ f ed it in diluted hydrochloric acid. He afterwards added dos^sof0 sulphuric acid. This addition produced a precipitate ofoxygen. sulphate of barytes, without any evolution of oxygen gas. The oxygen of the peroxide proved to have entered into combination with the hvdrochloric acid. By separating the precipitated sulphate, the oxidized acid was obtained in a separate state. In this way, Thenard obtained an oxidized hydrochloric acid, containing four times its volume of oxygen. It was an acrid and colourless liquid, nearly desti- tute of smell. It reddened vegetable blues. When boiled, nearly all the oxygen separated: when oxide of silver was added to it, chloride of silver immediately precipitated; water was formed, and oxygen evolved. By pursuing his researches, Thenard was enabled to oxidize this acid in a much higher degree. He re-oxi- dized the acid, obtained by the method just given, by repeating it fifteen times successively. The acid thus ob- tained, was found to contain seven times its volume of oxygen, at the temperature of 68°. By other methods, however, this chemist succeeded in combining a much larger portion of oxygen with this acid. After having ob- tained an acid, as highly oxidized as possible, by the method already indicated; he added to it sulphate of silver: chloride of silver was precipitated, and all the oxygen, previously combined with the oxyhydrochloric acid, except that necessary to form water with the hydrogen of the same acid, became united to the sulphuric acid, in the form of an oxysulphuric acid. He now added to this acid, a quantity of hydrochloric acid, less than existed in the oxidized acid, at first employed. Barytes was then added, just sufficient to precipitate all the sulphuric acid present. The excess of oxygen, in the latter acid, became instantly transferred to the hydrochloric acid; so as to form a very highly oxidized hydrochloric acid. If the previous step be taken of precipitating, in part, the sulphuric acid from the oxysulphuric acid (whereby it becomes more highly oxidiz- 192 ACIDS Book i. ed), before it is employed to form the oxyhydrochloric acid; Divu"'"11- the result will be the production of this acid, in the highest state of oxidizement, which Thenard was capable of effect- ing. By pursuing these processes, this chemist succeeded in obtaining an hydrochloric acid, containing 16 times its volume of oxygen. The combination of hydrochloric (muriatic) acid and oxygen, which has thus been discovered by Thenard, ought to have proved identical with chlorine (oxymuriatic acid); if the old theory, respecting the composition of the latter substance, had been correct. But this is very far from being the case. The advocates of the former doctrine may now satisfy themselves, that a real oxymuriatic acid and chlorine are distinct substances.* Water, sa- VIII. Water saturated with hydrochloric acid gas, is, witnhydro-^n common language, called muriatic acid. This solution of ohioricacid, the acid gas, in water, is the only form, in which the acid is quWhvdro-uset* *°r t*le OI"dinary purposes of chemistry, or in medi- chloric acid. cine. When hydrochloric acid is spoken of; it is to be always understood, unless otherwise specified, that the solution of the gas in water is meant. The liquid form of the acid will now be considered. LTQU1D HYDROCHLORIC ACID. Usual chemical name, Muriatic Acid. Liquid hy- 1. The Edinburgh college directs the following process ack£hho"C for obtaining the liquid acid: Expose two pounds of chlo- obtained ride of sodium, (common salt) to a red heat for some time. for medical After the chloride has cooled; put it in a retort, and pour upon it sixteen ounces of sulphuric acid, previously di- luted with one pound of water. Distil the mixture, in a sand bath, at a moderate heat, as long as any acid comes over. Prooess ex- 2. The explanation of this process is the same with that plained. glVen 0f the formation of the acid in the gaseous state; with this difference only, that the water, directed by the Edinburgh college, distils over in combination with the gaseous acid. Its proper- 3. Liquid hydrochloric acid, when perfectly pure, is fies* colourless; but, as usually obtained, it has a pale yellow colour, owing to the presence of a small portion of iron. It possesses the peculiar smell of the gaseous acid. When ex- * See Thenard's paper, as translated in the Annals of Philosophy, (Jan. 1819.) HVDROCHLORIC ACID. 193 posed to the air, it gradually emits the acid gas, which Cbap.ii. combines with the moisture of the atmosphere, and appears Spec, grav- in white fumes. It is about one and one-fifth times as heavy 1203' as water. 4. When the liquid acid is formed by saturating cold water with the acid gas, the water becomes hot; and, as the heating advances, the absorbing power of the water dimi- nishes, until the heat arrives at the boiling point, when it is entirely lost. Hence it is, that, if the liquid acid be exposed to heat, the acid gas may be procured. It was in this way that Dr. Priestley first obtained the acid in the gaseous form. 5. Liquid hydrochloric acid, when a perfectly saturated Composi- solution, contains 515 times its volume of the acid gas; ortion- more than half its weight. 6. Liquid hydrochloric acid acts as a stimulant, when Medical taken into the stomach. In low fevers of all kinds, when properties. diluted sufficiently to be agreeably sour, it is a very proper drink. In relaxed states of the stomach, it has been found useful in restoring the tone of that organ; but, for this pur- pose, liquid sulphuric acid is generally preferred. Almost any quantity of the solution may be taken, when sufficiently diluted. IX- Hydrochloric acid is not capable of combining with any of the undecompounded combustibles. When the at- tempt is made to combine the acid with some of them, it becomes decomposed; its chlorine forms a chloride with the combustible, and its hydrogen is evolved. X. Hydrochloric acid combines with some of the salifia- ble bases, and gives rise to a genus of salts, which will be called hydrochlorates. These salts are usually called mu- riates. Most of them, when exposed to a red heat, undergo a double decomposition; so as to be converted into a chlo- ride and water. XI. Hydrochloric acid is composed of SnSif" Chlorine 36—one atom. drochlom Hydrogen 1—one atom. acid. Giving 37 for the number represent- ing the weight of its atom. XII. This acid has been employed to destroy contagion, Employed and putrid miasmata. Morveau used it, with success, for JJVjjjJJJJ neutralizing the putrid exhalations, which pervaded the cathedral of Dijon. But, for these purposes, it is inferior to chlorine. 2 B 194 ACIDS. Book I. Division II. Iodine Iodine forms but one acid compound with oxygen; namely, add1 with° iodic acid# This acid wiU be described in thc following oxygen. section. , SECTION IV. OF IODIC ACID. Iodic acid; I. Iodic acid maybe obtained by the following process: how obtain-put jnto a D m tube, closed at one end, 100 grains of chlo- rate of potash; and pour upon them, 400 grains of hydro- chloric acid, of the specific gravity of 1*105. Make the bent tube communicate with a long necked receiver, containing 40 grains of iodine; and apply a gentle heat to the mixture, which it contains. A quantity of protoxide of chlorine is immediately formed. As soon as this gaseous oxide enters the receiver; each of its constituents combines with a por- tion of the iodine, and gives rise to the formation of two acids; the acid under description, and another acid, which is called chloriodic acid. By exposing the mixed acids to heat, the chloriodic acid, being volatile, flies off; while the iodic acid remains behind. This acid was first obtained, in a separate state, by Sir H. Davy. Its proper- H- Iodic acid is a white semi-transparent solid, destitute ties- of smell; but possessing a strong, astringent, sour taste. When exposed to a moist atmosphere, it gradually deli- quesces. When heated to a temperature, a little below that, at which olive oil boils; it is decomposed into iodine and oxygen. It sinks rapidly in sulphuric acid; hence its specific gravity must be considerable. It is readily soluble in water. Its solution first reddens, and afterwards destroys, vegeta- ble blues. When it is exposed to heat, the water gradually evaporates, and the acid is reduced to the consistency of syrup. Afterwards, if the heat be increased, the acid may be driven over unaltered; but, when the temperature arrives at a certain point, the acid becomes decomposed. III. Iodic acid has the property of combining with a number of acids, as was first ascertained by Sir H. Davy. With those already described, however, it does not appear capable of combining. When iodic acid and hydrochloric acid are brought into contact; they mutually decompose each other, and the products are water and chloriodic acid. Iodic acid combines with several of the salifiable bases, and forms salts, called iodates. HYDRIODIC ACID. 195 IV. Iodic acid is composed of Chap. II. Iodine 125—one atom. Composi- Oxygen 40—five atoms. tion of iodic Giving 165 for the number represent- ing the weight of its atom. Iodine forms but one acid compound with hydrogen; namely, Iodine hydriodic acid. This acid will be described in the follow- S^add, ing section. with hydro* gen. SECTION V. OF HYDRIODIC ACID. I. Hydriodic acid may be obtained, by exposing, in a Hydriodic retort, to heat, a mixture, moistened with water, of four obtained* parts of iodine, and one part of phosphorus. A gas is im- mediately formed, which must be collected over mercury. This gas is hydriodic acid. II. Hydriodic acid was discovered by Clements; but its properties were first investigated by Davy and Gay-Lussac. III. Hydriodic acid is an invisible and elastic fluid, like its proper- common air. Its smell is similar to that of hydrochloric ties- acid. Its taste is very sour. When brought in contact with chlorine, hydrochloric acid is formed, and iodine de- posited. IV. It is about four and a half times as heavy as com- Spec grav. 4443. mon air. V. Liquid hydriodic acid is readily formed by saturating Combines water with the gaseous acid. It may be formed also, by pass- mtix w*ter- ing a current of hydrosulphuric acid gas (sulphuretted hy- drogen) through water, in which a portion of iodine is pre- viously placed. The hydrogen of the acid combines with the iodine; and its sulphur is deposited. Liquid hydriodic acid may be concentrated by exposure to a heat, under 26*°. In this way, its specific gravity may be increased to 1*7. At the temperature of 262°, it boils, and may be distilled over. It has the property of dissolving iodine; whereby it assumes a dark colour. VI. Hydriodic acid is composed of Composi- Iodine 125—one atom. , d°iod°fhy' Hydrogen 1—one atom. aci,j Giving 126 for the number represent- ing its compound atom. 196 ACIDS Book I. Division II. Sulphur Sulphur forms three acid compounds with oxygen; namely, arith'wrtih6 sulphuric acid, sulphurous acid, and hyposulphurous acid. oxygen. These acids will be described in the three following sec- tions. Sulphuric acid; how obtained pure. Process ex- plained. Its proper- ties. SECTION VI. OF SULPHURIC ACID. Dissolves in water, and forms liquid sulphuric acid. I. Sulphuric acid may be obtained by the following pro- cess: Distil sulphate of iron (green vitriol), which has pre- viously been exposed to heat, to drive off its water of crys- tallization: a black coloured fuming substance will come over, very nearly twice as heavy as water; it constitutes the fuming sulphuric acid, as prepared, for many years, in Nordhausen in Germany. Distil this fuming liquid, in a retort, with a moderate heat, into a receiver surrounded with ice: a vapour is driven over; which condenses in the re- ceiver. If the distillation be stopped in time, the condensed vapour will consist of pure sulphuric acid. II. The fuming sulphuric acid of Nordhausen is consider- ed to be a very concentrated sulphuric acid, containing but little water. The manner of its preparation indicates this to be its nature; being distilled from dried sulphate of iron. Now when this fuming acid is distilled cautiously, nothing but the pure acid is driven over; what water it may have contained, being left behind. III. Sulphuric acid is a solid under the temperature of 66°; but above that temperature, it assumes the form of colourless vapour, which takes on the appearance of white clouds, when it comes in contact with moist air. In the solid form, it is composed of filaments, having a silky ap- pearance; which gives the acid some resemblance to the mineral substance, called asbestos. It is tough, and cannot be easily cut. When exposed to the air, it fumes, and gra- dually flies off in the form of vapour. When held between the fingers, it exerts no action upon the skin; but after some time, it produces pain. The specific gravity of this acid, either in the solid form, or in the state of vapour, has not been ascertained. IV. Sulphuric acid has a strong affinity for water. When thrown into this liquid; the combination takes place with such rapidity, as to produce a noise, similar to that caused by a red hot iron, under equal circumstances. Sulphuric acid, dissolved in a certain quantity of water, forms liquid sulphuric acid, or the sulphuric acid of commerce. SULPHURIC ACID. 197 Chap. II. LIQUID SULPHURIC ACID.------- Former name, Vitriolic acid. Common name, Oil of Vitriol. 1. When the pure solid sulphuric acid is dissolved in Liquid sul- about one-fifth of its weight of water, it forms liquid sul- P«»uricac,d; phuric acid, of the usual strength, in which it occurs in commerce. 2. Liquid sulphuric acid is obtained by the manufacturer, how obtain- by burning a mixture of one part of nitrate of potash (ni-JjJJjJfrJJ tre) and seven parts of sulphur, in chambers lined withturer. lead; whose floors are covered with a certain depth of wa- ter. The water becomes impregnated with the acid; and when the impregnation has reached to a certain degree, the acid water is concentrated, by evaporation, first in leaden retorts, as long as the acid is too weak to act upon them; and afterwards in glass retorts, until it become of a certain strength. This strength, for the purposes of commerce, is indicated by a specific gravity of about 1*85. The acid may be concentrated beyond this strength; but it has not been found possible, by any distillation, to drive off all the water, which it contains. 3. The rationale of the formation of liquid sulphuric acid Manofac by the above process, is thus given by Clement and Desor- c"£8iIe^_pro" mes, and Davy. The combustion of a mixture of sulphur plained. and nitrate of potash (nitre) gives rise to the formation of sulphurous acid and deutoxide of azote (nitrous gas). The latter of these substances is immediately converted into ni- trous acid, by coming in contact with the air. The acid thus formed and the sulphurous acid then combine, lose their gaseous form and precipitate into the water. As soon as the combined acids come in contact with the water, the sulphurous acid becomes converted into sulphuric acid, by combining with a dose of oxygen, at the expense of the ni- trous acid; which latter is thereby brought back to the state of deutoxide of azote; and thus changed, assumes, again, the gaseous form. No sooner does it come in contact with the air, than it is again converted irito nitrous acid, precipi- tates in combination with sulphurous acid, converts the lat- ter acid into sulphuric acid, and again assumes the gaseous form, as deutoxide of azote. The same round of composi- tions and decompositions is repeated as long as any sul- phurous acid may remain. 4. Liquid sulphuric acid was discovered, in the middle Account of ages, either by the Arabian chemists, or the alchemists. It ^e^"of is spoken of by Basil Valentine, who wrote early in the fif- the liquid teenth century. It was, for a long time, obtained by dis- acld- tilling sulphate of iron (green vitriol); a process which is 198 ACIDS. Book i. still followed in Germany. It was afterwards prepared by Division n. burning a mixture of 3ulphur and nitrate of potash (nitre) under a glass bell. From this mode of preparation, it was formerly frequently called oleum sulphuris per campanam. The method, which has been described at length in the be* ginning of the present account, and which is pursued by al- most all the manufacturers of sulphuric acid, was invented by Dr. Roebuck; who established the first manufactory of the kind, at Prestonpans in Scotland. Properties 5. Liquid sulphuric acid is colourless like water. It is nearly acid.C l(1U' destitute of smell, but possesses an intensely sour taste. It has somewhat of an oily consistency; from which circum- stance it has got the common name of oil of vitriol. It red- dens vegetable blues. It acts upon animal and vegetable substances with considerable energy, and speedily converts them into charcoal. Its specific gravity and boiling point vary with the quantity of water which it may contain. When composed of Sulphuric acid 40—one atom, Water 9—one atom; its specific gravity is 1*85,—and its boiling point, 620°. When com- posed of Sulphuric acid 40—one atom, Water 18—two atoms; its speci- fic gravity is 1*78,—and its boiling point, 435°. When com- posed of Sulphuric acid 40—one atom, Water 27—-three atoms; its spe- cific gravity is 1*65, and its boiling point, 350°.—Water, however, does not combine with sulphuric acid, only by atoms. So far from this being the case, it appears capable of uniting with the acid, in every proportion. It is not easy to reconcile this fact with the atomic theory. 6.- Liquid sulphuric acid, when exposed to the air, at- tracts moisture, and becomes heavier. The quantity of wa- ter, which it is capable of absorbing in this way, is always less, as the quantity of this liquid, which it already contains, is greater. 7. The congealing point of liquid sulphuric acid varies with its density. But it is found that this variation takes place in such a way, as that the freezing point of the acid lowers, according as its density varies, either above or be- low a certain density. The freezing point of liquid sulphu- ric acid, of the specific gravity of 1*78 is at 45°. Now it is found, that if the acid be much more, or much less con- centrated; its freezing point lowers considerably. When SULPHURIC ACID 199 concentrated as far as possible, its freezing point is as low Chap. h. as — 36°. 8. Liquid sulphuric acid is decomposed by many of the Action of undecompounded combustibles. SS/aJli [1.] When liquid sulphuric acid and hydrogen are made combusti- to pass together, through a red hot porcelain tube; the acid b,es- is completely decomposed, water is formed, and sulphur de- posited. At a boiling temperature, it is converted, by char- coal, into sulphurous acid; but by the action of the same com- bustible, at a red heat, it is totally decomposed. When heated in contact with phosphorus; sulphurous acid is dis- engaged, and the phosphorus becomes converted into phos- phoric acid. When boiled along with sulphur, it becomes converted into sulphurous acid. [2.] Liquid sulphuric acid, when very much diluted, acts violently upon zinc and iron. Part of the water present is decomposed; these metals are oxidized, and hydrogen is evolved. When the acid is concentrated, it acts upon these metals, but much less violently; part of the acid, in this case, being decomposed, and flying off in the form of sulphurous acid. Upon tin and copper, the action of the liquid acid is but feeble, unless it be assisted by heat; in which case, it oxidizes and dissolves them. On silver, mercury, antimony, bismuth, arsenic and tellurium, a pretty high temperature is required for the acid to produce any effect; and the action, which takes place, consists in the oxidizement of these me- tals, at the expense of part of the acid, which flies off in the form of sulphurous acid; while the remainder combines with the oxides formed. At the boiling temperature, it oxidizes lead, and dissolves cobalt, nickel and molybdenum. The liquid acid exerts no perceptible action upon gold or platinum. 9. When liquid sulphuric acid is dropped into a concen- trated solution of iodic acid; the two acids fall, in combina- tion, in the form of a solid precipitate. This precipitate, after fusion, assumes the form of crystals, which have a pale yellow colour. When strongly heated, it is partly sub- limed, and partly decomposed into oxygen, iodine and sulphuric acid. 10. Gay-Lussac, has lately succeeded in oxidizing liquid The liquid sulphuric acid. His method consisted in adding his recent- ^ ofbeine ly discovered oxyhydrochloric acid to sulphate of silver, oxidized. The products are chloride of silver, water and oxysulphuric acid. The formation of oxysulphuric acid has already been noticed, when detailing the different methods for obtaining oxyhydrochloric acid, page 191. 200 ACIDS. Book I. 11. Liquid sulphuric acid, when sufficiently diluted, fur- P*waion IL nishes a very powerful article to the materia medica. Its The liquid general action is that of a stimulant and tonic. In weak ?n m«3f-d and relaxea* states of the stomach, it is used to excite appetite cine. and to promote digestion. It is a useful acidulous drink, in all fevers, below the par of action. When taken in large quantities, it passes off by the kidneys and the skin. V. Sulphuric acid combines with the salifiable bases, and forms salts, which are called sulphates. These salts will be described under the heads of their respective bases. Composi- yj# Sulphuric acid is composed of tion of sul- r oil r. „ phuricacid. bulphur 16—one atom. Oxygen 24—three atoms. Giving 40 for the number represent- ing its compound atom. SECTION VII. OF SULPHUROUS ACID. Phlogisticated Sulphuric Acid, of Stahl. Sulphurous I. Sulphurous acid may be obtained by the following TteinetT Process: Expose a mixture of two parts of mercury, and one part of sulphuric acid, in a retort, to the heat of a lamp: an effervescence takes place, and a gas is extricated, which must be collected, in glass vessels, over mercury. This gas is sulphurous acid. In this process, the mercury robs the sulphuric acid of just so much oxygen, as to convert it into sulphurous acid; which, being a gas, causes the effervescence, just spoken of. The acid gas is collected over mercury, in consequence of its absorbability by water. Its history. II. Sulphurous acid was first examined by Stahl. About the year 1774, Scheele and Priestley obtained it in the ga- seous form, and described many of its properties. Since that time, it has been thoroughly examined, by Berthollet in 1782 and 1789; by Fourcroy and Vauquelin in 1797, and by Thomson in 1803. its proper- III. Sulphurous acid is a gaseous fluid, transparent and ties. colourless, like common air. Its taste is exceedingly acid and sulphurous. Its smell is strong and suffocating, resem- bling exactly, that produced by the burning of sulphur. It changes vegetable blues, first to red, but afterwards destroys them. It destroys the colours of many animal and vegetable substances; which property makes it useful in the bleaching HYPOSULPHUROUS ACID. 201 •f wool, and for removing stains from linen, produced by Chap. n. fruit. IV. Sulphurous acid gas is about two and one-fifth times Spec. grav. as heavy as atmospheric air. When exposed to a cold of 2'22- — i 8-, in a state of compression, it is condensed into a li- quid. It does not support combustion. Neither is it fit for respiration. Animals forced to breathe it are very soon des- troyed. V. Water, when perfectly saturated, contains 33 times Absorbable its volume of this acid gas: or by weight, 100 parts of wa-bywater' ter take up 91*5 parts of the gas. When thus combined with water, it constitutes liquid sulphurous acid. It is very littie heavier than water. It may be frozen, without parting with any of the gas which it contains. VI. Sulphurous acid gas and oxygen gas, when dry, do not act upon each other; but if moist, they combine gradu- ally, and the product is sulphuric acid. These gases com- bine also by heat and electricity. VII. At a red heat, sulphurous acid gas is decomposed Action of by hydrogen and charcoal; water and carbonic acid are f°mbusti- formed, and sulphur deposited. It is not decomposed by sulphur or phosphorus, under similar circumstances. VIII. Of the metals, sodium and potassium decompose this acid gas readily. Iron dissolves in it, without the evo- lution of any gas. The peroxides of lead and of manganese absorb it, and are converted into sulphates of these metals. This occurs in consequence of the transfer of part of the oxygen of these oxides, to the sulphurous acid; where- by the latter is converted into sulphuric acid. The action of the other metals on this acid gas, is but imperfectly known. IX. Sulphurous acid gas is composed of Composi- Sulphur 16—one atom. tionofsul- /-v .. * phurous Oxygen 16—two atoms. aCy# " Giving 32 for the number representing its compound atom. SECTION VIII. OF HYPOSULPHUROUS ACID. I. Oxygen combines with sulphur in a smaller proportion Hyposul- than that which exists in sulphurous acid. This compound add'has ne* of oxygen and sulphur exists in certain salts, which have yer been been called hyposulphites. Although it has never been ob- a^eparau 2 C state. 202 ACIDS. Book I. Division II Book I tained in a separate state, it is supposed to possess acid pro- ' perties, and the name hyposulphuric acid has been assigned to it. II. It is considered to be composed of Sulphur 16—one atom. Oxygen 8—one atom. Giving 24 for the number represent- ing its atom. Sulphur Sulphur forms two acid compounds with hydrogen. These forms two compounds are usually known by the names of sulphu- nydrogenh retted hydrogen, and supersulphuretted hydrogen. They will be described in the two following sections, under the names of hydrosulphuric acid, and hydrosulphurous acid.* SECTION IX. OF HYDROSULPHURIC ACID. Usual chemical name, Sulphuretted Hydrogen. Hydrot/uonic\ Acid, of the German Chemists. Hydrosui- I. Hydrosulphuric acid may be obtained by pouring phuricacid; diluted sulphuric acid upon the mass formed by fusing to- ed.W ' gether, in a crucible, three parts of iron filings and two parts of sulphur. The gas, which becomes immediately extricated, consists of hydrosulphuric acid. It must be collected over mercury; being absorbable by water. When obtained by this process, however, it is generally contaminated with hy- drogen. It may be obtained, perfectly pure, by digesting * These names were proposed by me, for the compounds of sulphur and hy- drogen, in an essay, which I read in 1812, before the Columbian Chemical So- ciet), and which was published, the succeeding year, in their Memoirs.§ The same name has been proposed for one of them, namely sulphuretted hydrogen, by Gay-Lussac. I have adopted the name hydrosulphuric acid, for sulphuretted hydrogen, not only because the compound has acid properties; but especially because recent discoveries have made chemists acquainted with acids, precisely analogous in composition, in which a similar plan of nomenclature has been adopted, or pro- posed by high authority. The acids alluded to are the hydrochloric, the hydri- odic, and the hydrocyanic acids. With regard to the supersulphuretted hulro- gen, this compound is probably a binary combination of sulphur and hydrogen. it combines with some of the salifiable bases, and forms compounds, in many respects, analogous to salts These circumstances, together with that of its con- taining less hydrogen than sulphuretted hydrogen, have induced me to venture upon giving it a name, with the characteristic termination of a sub-acid, and to place it among the acid bodies. t From hydrogen and frjjov sulphur. § Memoirs of the Columbian Chemical Society, p. 1>0 HYDROSULPHURIC ACID. 203 sulphuret of antimony, in powder, in hydrochloric (muriatic) Chap, ir acid. II. The properties and composition of this gas were first its history. investigated by Scheele in 1777. The gas was further examined, in 1786, by Kirwan; who first shewed that it possessed acid properties. This conclusion of Kirwan was fully confirmed by Berthollet in 1794. It was still further investigated by Berzelius in 1807; and, more lately, by Gay-Lussac and Thenard, and Davy. III. Hydrosulphuric acid is a colourless and elastic fluid, its proper- like common air. Its smell is strong and fetid, not unlike ties that of rotten eggs. When in solution in water, it converts vegetable blues to red. It is about one and one-fifth times Spec grav. as heavy as common air. It is capable of combustion. When 1-19- set on fire, it burns with a bluish-red flame; and a quantity of sulphur is deposited. When electric sparks are passed through it; it is converted into an equal bulk of hydrogen gas; the sulphur being deposited. When its combustion is complete, it is converted into water and sulphurous acid. IV. This acid gas is not fit for respiration. Animals forced to breathe it are destroyed. V. Hydrosulphuric acid gas is rapidly absorbed by water; Forms with in which state of solution, it forms liquid hydrosulphuric J^J^^,. acid. When the liquid acid is a perfectly saturated solution, sulphuric it contains about two and a half times its bulk of the gas. J^ *£jj The liquid acid possesses the property of precipitating nearly all nearly all the metals from their solutions. The metal falls the metals. generally as a sulphuret; the hydrogen of the acid and the oxygen of the metallic oxide, going to form water. The acid, therefore, becomes a very useful test for the presence of metals in solution; more especially as the colour of the precipitate produced most generally indicates the particular metal present. The colour of the metallic precipitates, which it produces, may be seen in the following statement. Gold and Platinum are reduced. Lead is precipitated **'»<*■ Silver is precipitated Black. Zinc White. Mercury Black Bismuth Black. Palladium Dark-brown. Antimony Orange. Copper Black. Arsenic. Yellow. I'in Brown. Molybdenum. Chocolate. Iron, nickel, cobalt, manganese, cerium, uranium and tita- nium are not precipitated from solution, in the mineral acids, by liquid hydrosulphuric acid; and but imperfectly from solution in vegetable acids. VI. Hydrosulphuric acid combines with most of the Forms with salifiable bases, and forms a set of compounds, which arebases'h.v 204 AClDS. Book I. very analogous to salts. These combinations will be describ- Division II. e(j un(ier tne hetids of their respective bases. drosul- VII. Hydrosulphuric acid is composed of Its'compo- Sulphur 16—one atom. sition. Hydrogen 1—one atom. Giving 17 for the number represent- ing the weight of its atom. SECTION X. OF HYDROSULPHUROUS ACID. Usual chemical names, Hydroguretted Sidphur.—Supersulphuretted Hydrogen Hydrosul- I. Htdrosulphurous acid may be obtained by adding, acid^how gra(luaUy, hydrochloric (muriatic) acid, to the brown- obtained, coloured liquid, obtained by boiling together, liquid potash and sulphur. Hydrosulphuric acid is evolved, and, at the same time, a substance precipitates. This substance is hydrosulphurous acid. II. Hydrosulphurous acid was first noticed by Scheele; but it was Berthollet who first ascertained its chemical nature. Its proper- III. Hydrosulphurous acid is a liquid of a yellowish- t,es" brown colour, having considerable resemblance to oil. When exposed to heat, it drops a portion of its sulphur, and exhales in the form of hydrosulphuric acid gas. A si- milar decomposition of it takes place upon exposure to air. It forms, with some of the salifiable bases, compounds, which are usually called hydroguretted sulphurets. They will be called, in the present work, hydrosulphites, and be described under the heads of their different bases. Selenium Selenium forms one acid compound with oxygen; namely, nlc'a'cicf16 selenic acid. This acid will be noticed in the following with oxy- section. gcn SECTION XI. OF SELENIC ACID. Selenic I. Berzelius has ascertained, that if selenium be heated acid; how \n a large flask, full of oxygen gas or atmospheric air, it evaporates, without undergoing combustion, and is convert- ed into a gaseous oxide. This fact ought to have been HYDROSELENIC ACID. 205 mentioned under the head of selenium. On the other hand, Chap. DT. if selenium be exposed to heat in a hollow globe of glass, ——— about an inch in diameter, in which it has not room to evaporate, and a current of oxygen be made to pass through it; this peculiar substance, at the moment of ebullition, enters into combustion, with a flame, white at its base, but green, or bluish-green, at the edges, and sublimes without residue. The sublimed product is selenic acid. Selenium is converted into selenic acid also, by the action of nitric or sul- phuric acid, or aqua regia. II. Selenic acid, immediately after it is formed, has a Its proper- lustre peculiar to itself, which it soon loses by the absorp- ties- tion of humidity from the air. It has an acid taste, leaving a weak burning sensation upon the tongue. In the form of gas, it has a penetrating odour. It dissolves readily in cold water, and in all proportions in boiling water. It combines with salifiable bases, so 'as to form peculiar salts. III. Selenic acid is composed, in whole numbers j of Composi- Selenium 40—one atom. ton- Oxygen 16—two atoms. Giving 56 for the number representing the weight of its atom.* Selenium forms one acid compound with hydrogen, which Selenium is called by Berzelius, selenuretted hydrogen. It will droTeienie be noticed, in the following section, under the name of acid with hydroselenic acid. hydrogen. SECTION XII. OF HYDROSELENIC ACID. I. Hydroselenic acid may be procured, by pouring di- Hydrose- luted hydrochloric (muriatic) acid upon selenuret of potas- nenic ?"^; sium, contained in a small retort. The selenuret swells and ed. becomes red, and a gas is extricated. This gas is hydrose- lenic acid. It was discovered by Berzelius. II. Hydroselenic acid is an invisible and elastic fluid, Its proper- like common air. It acts, with great violence, upon the41". organs of respiration and of smell. A bubble of the gas, not larger than a pea, is capable of destroying the sense of smell, so far, as not to be sensible to the impression of am- monia for several hours. The irritation, which it produced, * Berzelius, Annates de Chimie et de Physique IX. 231. et seq. (Nov. 181 SO 206 AC1DS Book I. caused a violent defluxion from the nose, and the eyes to Division II. become instantly red. Ir dissolves in .vater, totally deprived of air, without decomposition; but ihc presence of the smallest quantity of air, causes the solution to assume a red colour. This appearance of a red colour is owing to the reduction of the selenium; the hydrogen of the acid, com- bining with the oxygen of the common air present, forming water. The solution is colourless, and possesses an hepatic taste. It stains the skin of a brown colour, which cannot be removed by washing. It becomes decomposed by exposure to air, first in the upper parts, but afterwards the whole, and changes throughout to a red colour; the selenium being reduced. It precipitates all metallic solutions, not excepting those of zinc and iron, when in a neutral state. All these precipitates are of a black or brown colour, except those of zinc, manganese, and cerium, which are of a flesh colour. The acid gas combines with some salifiable bases, and forms compounds analogous to salts. Composi- ui# Hydroselenic acid is composed, in whole numbers, of Selenium 37 Hydrogen 1 38*.—Supposing it a com- pound of one atom of each of its constituents; then the weight of an atom of selenium would be represented by the number 37. Thus it is perceived, that the same equivalent number cannot be deduced from the consideration of the selenic and hydroselenic acids. tion Tellurium Tellurium forms one acid compound with oxygen; namely, forms td- telluric acid. This acid will be noticed in the following luric acid with oxy- section. *en- SECTION XIII. OF TELLURIC ACID. Telluric I» Tellurium forms, with oxygen, but one compound, acid, al- which, in different salts, sometimes performs the part of an *!2!L?« o acid, and sometimes of a salifiable base. As the account of salifiable the salifiable bases precedes that of the acids, in this work, base- it became necessary to describe this compound first as a salifiable base; and this is done under the head of tellurium, page 49. It is mentioned here incidentally, in order that * Berzelius, AnnalesdeChimie etde Physique IX. p. 231. et seq. (Nov. 1818.) HYDROTELLURIC ACID. 207 the enumeration of the acids, embraced by the present Chap, h. class, may be complete. Tellurium forms one acid compound with hydrogen. This Tellurium combination is generally called telluretted hydrogen. It telluric will be noticed, under the name of hydrotelluric acid, acid, with in the following section. hydrogen. SECTION XIV. OF HYDROTELLURIC ACID. I. Hydrotelluric acid may be formed by pouringHydrotei- diluted sulphuric acid upon a mixture of oxide of tellurium, 'unc a"d.» potash and charcoal, the latter having been previously ex- ed. posed to a red heat. A gas is immediately evolved, which must be collected over mercury. This gas is hydrotelluric acid. It was discovered, in 1809, by Sir H. Davy. II. Hydrotelluric acid is a colourless and elastic fluid Its proper like common air. Its smell is strong and peculiar, andties" somewhat resembles that of hydrosulphuric acid (sulphu- retted hydrogen). It burns with a bluish flame, and is con- verted into oxide of tellurium. Its solution in water has a claret colour. Like hydrosulphuric acid, it precipitates most metallic solutions. It is capable of neutralizing salifiable bases, with which it forms compounds analogous to salts. CLASS II. ACIDS, WHOSE BASES FORM ACID COMPOUNDS, WITH OXYGEN ONLY. Acids belonging to this class are 1. Nitric Acid. 2. Nitrous Acid. 3 Hyponitrous Acid ■V. Carbonic Acid. 5. Boracic Acid. 6. Phosphoric Acid. 7. Phosphorous Acid. 8. Hypophosphorous Acid. 9- Arsenio Acid. 10. Arsenious Acid. 11. Chromic Acid. 12. Molybdic Acid. 13. Molybdous Acid. 14. Tungstic Acid. 15. Colurobic AHd. 18. Antimonic Acid. 17. Antimonious Acid. Second class of acids enu- merated. These acids will be described, in the order in which they have been enumerated, in the following sections. 208 ACIDS Book I. Division II. Azote Azote forms three acids with oxygen; namely, nitric acid, acidhwitb.6 nitrous acid, and hyponitrous acid. These acids will be oxygen. described in the three following sections. SECTION I. OF NITRIC ACID. Common names, Spirit of Nitre.—Aqua Fortis. Nitric acid; I. Nitric acid may be obtained by the following pro- ^ow obtain-cess. Mix tWQ parts 0f nitrate of potash (nitre) with one part of sulphuric acid, in a glass retort. Adapt, to the mouth of the retort, a receiver, from which a glass tube passes into one of the exterior openings of a bottle with three mouths. Pour a little water into the bottle, and fix a tube of safety* to its central mouth. To its third mouth, adjust a second tube, and let it communicate with the pneumatic trough. The apparatus being thus arranged, apply heat to the retort, and gradually increase it, until it reach the tem- perature of 500°. A vapour is evolved, which condenses in the receiver. This condensed vapour consists of nitric acid, holding in solution a portion of deutoxide of azote (nitrous gas). Expose it, for some time, to the influence of heat: the deutoxide of azote will be driven off; and the nitric acid, left behind. The nitric acid is formed in this process, in consequence of the decomposition of the nitrate of potash. The sulphuric acid combines with its potash, while the nitric acid is extricated in the form of vapour. II. The Edinburgh college directs the following process for preparing nitric acid: Expose nitrous acid, in a retort^ furnished with a receiver, to a very gentle heat, until its reddest portion shall have passed over. What remains in the retort will be nitric acid. The liquid, which is called by the Edinburgh college, nitrous acid, is in fact nitric arid, holding, in solution, a quantity of deutoxide of azote (nitrous gas). The same kind of nitric acid is obtained in the process detailed in the preceding paragraph. When it is exposed to heat, the deutoxide of azote is driven off. • A tube of safety is a tube, which is fixed in vessels, in which distillations are made, with one end open, communicating with the external air, and the other immersed below the surface of the liquid contained in them. It has the eff-ct of preventing the bursting of vessels; for if a vacuum take place, the air rushes down the tube of safety, and restores the equilibrium of pressure. On the other band, if any gaseous fluid be suddenly extricated, the contained liquid is forced up the tube. NITRIC ACID 209 III. Nitric acid appears to have been first obtained bv Chap ii. Ravmond Lully, a chemist, who lived in the 13th centurv. ~-----~ IV. Nitric acid, when recently prepared, is a transparent its proper- and colourless liquid like water. Its taste is exceeding acrid, ties, It corrodes rapidly animal substances of all kinds. When applied to the skin, it stains that membrane of an indelible yellow colour. It constantly emits white fumes, which have an acrid and disagreeable odour. It is very readily decom- posed; even the action of light will cause it to evolve oxy- gen gas, and to form deutoxide of azote, whereby it assumes a yellow colour. V. Nitric acid has never been obtained perfectly free Always from admixture of water. When as much concentrated as conta,n» possible, it is about one and a half times as heavy as spec, grav, water. Whtn its sp. cific gravity is 1'42, its boiling point 1'55- is at the temperature of 248°. If it be more or less concen- trated, its boiling poin* is lower. When exposed to the temperature of — 66°, it begins to congeal; and, if agitated, is converted into a mass of the consistence of butter. The fact, that nitric acid has never been obtained free from water, proves the strong affinity which it has for this liquid. It attracts moisture from the atmosphere; but not with the same avidity as sulphuric acid does. VI. Nitric acid is capable of combining with oxygen, as May be Thrnard has lately discovered. This chemist obtained the oxldlzed l« oxidized acid in the following manner:—Peroxide of barium grees. w--.s first moistened with water, so as to make it fall to powrier, and then mixed with seven or eight times its Weight of water. Diluted nitric acid was now added to the mixture: no gas was evolved, and the solution was found to be neutral. Upon adding sulphuric acid to the solution, sulphate of barytes was immediately precipitated; and the second dose of oxygen of the peroxide, instead of being evolved, was transferred to the nitric acid. After the in- soluble sulphate was removed, the remaining liquid proved to be an oxidized nitric acid. Oxy nitric acid is a colourless liquid. It is capable of reddening vegetable blues. It pos- sesses most of the properties of nitric acid. When heated, it parts with its oxvgen, but not completely, unless after being kept boiling for a considerable time. It was concen- trated so far, by Thenard, as to contain eleven times its bulk of oxygen. It combines with some of the salifiable bases, with which it forms very decomposable, non-crystal- lizable salts.* * The fact* above given, respecting oxynitric acid, were taken from a trans« Itktion of Tbenard's paper, in the Annuls of Philosophy. 2 R 210 ACIDS. Book I. Division II Action of combusti- bles upon nitric acid. Nitric acid absorbs deutoxide of azote. It is de com posed, when mix- ed with hy< droabloric acid. It forms ni- trates with bases. Composi- tion. VII. Nitric acid is decomposed by all the combustibles, ex- cept the diamond, gold, platinum, palladium, rhodium, and columbium. It is not affected by hydrogen, at the common temperature of the air; but, if passed along with this com- bustible, through a red-hot porcelain tube, a violent detona- tion takes place; water is formed, and azote evolved. When poured upon charcoal, perfectly dry and minutely divided, it is decomposed with such rapidity, that the charcoal is instantly inflamed. In like manner, it inflames phosphorus and sulphur, at high temperatures. When poured upon perfectly dry iron filings, it parts with its oxygen so suddenly, as to set them on fire. The same effect is pro- duced, when the acid is poured upon zinc, tin, or bismuth, in a state of fusion. When poured upon drying oils, it sets them on fire instantaneously. The same effect is produced upon other oils, provided a little sulphuric acid be first added to them. VIII. Nitric acid has the property of absorbing deutox- ide of azote (nitrous gas), in different proportions. This combination was formerly called phlogisticated nitric acid. When the gas is placed in contact with the acid, the latter becomes at first a pale yellow, then a bright yellow. After a considerable quantity of the gas is absorbed, the acid becomes dark-orange, then olive, which colour increases in intensity, as the absorption proceeds. The next colour, which appears, is bright-green; and lastly, when fully sa- turated, it is blue-green. IX. When nitric acid is mixed with hydrochloric (mu- riatic) acid, a decomposition instantly takes place, and the odour of chlorine becomes perceptible. Part of the nitric acid is decomposed into deutoxide of azote (nitrous gas) and oxygen. The deutoxide of azote remains in solution in the acid; the oxygen combines with the hydrogen of the hydrochloric acid, while the chlorine of the latter is evolv- ed. The mixture of nitric and hydrochloric acids was former- ly called aqua regia. X. When nitric acid is poured upon iodic acid, in a con- centrated state, white crystals are deposited, which, upon drying, are partly sublimed, and partly decomposed into iodine, oxygen, and nitric acid. XI. Nitric acid combines with the different salifiable bases, and forms a set of salts called nitrates. These salts will be described under the heads of their respective bases. XII. Nitric acid is composed of Azote 14—one atom. Oxygen 40—-five atoms. Giving 54 for the number representing the weight of its atom. NITRIC ACID. 211 XIII. Priestley and Lavoisier made the preparatory in- Chap. II. vestigations, which led to the discovery of the constituents Account of of nitric acid. Lavoisier had suspected, from an experi- the disco- ment, in which he decomposed nitrate of potash (nitre) by JJJJtJl,!1' charcoal, that the base of nitric acid is azote. Several of ents. Dr. Priestley's experiments seemed to show the same thing. But its particular constituents were not absolutely demonstrated, before Cavendish made his celebrated expe- riment of forming nitric acid, by passing repeated shocks of electricity, through a mixture of oxygen and azotic gases. XIV. Nitric acid, in a state of vapour, has been employ- Nitric acid ed to destroy the contagion, or noxious effluvia, with which faffo*^ jails, hospitals, ships, and over-crowded places, are liable to u-oying^ become infected. The manner, in which it is employed, is to co"tag,?n» &no noxious put half an ounce of nitrate of potash (nitre) in a saucer, effluvia. placed in an earthen vessel, filled with heated sand. To the nitrate of potash, two drams of sulphuric acid are to be added; which decomposes the nitrate, the nitric acid flying off in a state of vapour. The nitric fumes, from the decom- position of half an ounce of nitrate of potash, are calculated to be sufficient to fill a cube of ten feet. The application of nitric acid vapour, to the purposes of purifying infected apartments, was first made by Dr. Carmichael Smyth; who received for his discovery, from the British govern- ment, a reward of five thousand pounds. XV. Nitric acid constitutes an important article of the Nitric aeid, materia medica. Its action appears to be that of a very an import- powerful stimulant. It has been used, with advantage, in cine. low typhus fevers. In the venereal disease, when combined with deutoxide of azote (nitrous gas), under the form of what is commonly called nitrous acid, it has been used with unequivocal advantage. It has suspended all the symptoms of that disease, whether of its first or second stage; and, in some cases, they have not returned. It cannot, however, be depended upon as a remedy in syphilis; but as an auxiliary means in its treatment, in some cases, it is of indispensable importance. These cases are such, in which, from an impaired constitution, mercury cannot be resorted to at once. Here then the acid removes the more alarming symptoms, increases the strength of the system, and thereby prepares the way for the subsequent exhibition of mercury. 212 ACIDS Book I. Division II. SECTION II. OF NITROUS ACID. Nitrous L Nitrous aciD may be obtained by distilling perfectly lacid; how j . i i « c j • u • A obtained "rv nitrate ot lead in a retort, fitted with a receiver. A pure, liquid comes over, which is nitrous acid. II. Nitrate of lead is composed of nitric acid and pro- toxide of lead. When it is exposed to heat, the lead becomes peroxidized at the expense of the acid, which distils over in the form of nitrous acid. discover- III. This acid was discovered by Scheele. This chemist Seheel found, that, when nitrate of potash (nitre) was exposed, lor a certain time, to a red heat, a quantity of oxygen was ex- tricated; yet the neutral properties of the salt were not altered. If acetic acid be poured upon this salt, Vapours of nitrous acid are evolved. Properties. IV. Nitrous acid is an orange-coloured, very volatile, fuming liquid. Its taste is very sour. When mixed with water, an effervescence ensues, and deutoxide of azote (nitrous gas) is extricated. It, therefore, appears incapable of uniting with water. Spec grav. V. It is somewhat less than one and a half times as 1*51- heavy as water. Its boiling point is at the temperature of 82°. VI. It combines with many of the salifiable bases, and forms a set of salts called nitrites. These salts will be described under the heads of their respective bases. Composi. VII. Nitrous acid is composed of Azote 14—one atom. Oxygen 32—four atoms. Giving 46 for the number representing the weight of its atom. SECTION III. OF HYPONITROUS ACID. Hyponi- I. Gay-Lussac has made it probable, from his experi- Us^xwt!- ments' l^at there is another compound of azote and oxygen, ewe ren- possessing acid properties, which contains less oxygen than babieb"*" nitrous acid. To this combination he gives the name of Gay-Lus- pernitrous acid. The name adopted here is that proposed WK>. CARBONIC ACID. 213 by Dr. Thomson. This compound has never been obtained Goat. II. in t separate state; neither is it known whether it is capa- ~ ble of combining with salifiable bases. II. It appears to be composed of Azote 14—one atom. Oxygen 24—three atoms. Giving 38 tor the number representing its atom. Carbon forms but one acid by combining with oxygen; Carbon namely, carbonic acid. This acid is described in the fol-^"^d lowing section. *'>th oxy- gen. SECTION IV. OF CARBONIC ACID. Sy n. Fixed Air.—Aerial Acid —Mephitic Acid.—Calcareous Acid. I. Carbonic acid may be obtained by pouring sulphuric Carbonia acid upon a quantity of chalk, mixed with water. An obtaineT effervescence takes place, and a gas is extricated: this gas is carbonic acid. II. Chalk is a compound of the acid under description and lime. The sulphuric acid poured upon it combines with the lime, and displaces the carbonic acid, which flies off in the form of gas. III. Carbonic acid is a gaseous fluid, invisible and|jM>roP«" elastic like common air. It is destitute of smell. It reddens tincture of turnsol, but no other vegetable colour. It is not altered by exposure to heat in close vessels, or by be- ing passed through a red-hot tube. IV. It is a little more than one and a half times as heavy Spec. grav. as common air. Its weight is sufficient to admit of its being 1-527- pour-d from one vessel to another. V. Carbonic acid does not support combustion. When a lighted candle is plunged into the gas, it is immediately extinguished. The same effect is produced when the gas is poured upon a burning body. It is not fit for supporting respiration. VI. At the temperature of 55°, water absorbs a little Absorbable more than its bulk of this gas, and suffers a small increase by water' in its specific gravity. At the temperature of 35°, liquid carbonic acid has no taste; but at 88°, it becomes sparkling, 214 ACIDS. Book I. and agreeably acid. Ice is not capable of absorbing this Difwon II. gas; aQ(j j£ water, saturated with it, is either frozen or boiled, the whole of the gas is separated. By artificial pressure, water may be easily made to take up six times its bulk of this ga6, or even a much larger quantity. Water, when thus impregnated, and a portion of carbonate of soda dissolved in it, constitutes the soda water, which is so largely drunk, in the summer season, in the cities of the United States. Action of VII. The undecompounded supporters do not appear to bies. U8t* nave auy action upon carbonic acid. Of the combustibles, charcoal, at a red heat, robs it of part of its oxygen, and converts it into carbonic oxide. Phosphorus is capable of decomposing this acid when combined with lime, by means of heat; phosphoric acid is formed, which combines with the lime, and charcoal is deposited. Combines VIII. Carbonic acid combines with salifiable bases, and and forms8' f°rms a set of compounds called carbonates. These salts carbonates, will be described under the heads of their respective bases. Composi- IX. Carbonic acid is composed of Carbon 6—one atom. Oxygen 16—two atoms. Giving 22 for the number representing the weight of its atom. Carbonic X. The nature of carbonic acid was gradually ascertain- t*oHades-Wn et* ^y tne successive labours of chemists. Hales had noticed that a certain air could be separated from limestone and similar substances, and that it was one of their constituents. The bare fact of its existence was all that was known con- cerning it, before the discoveries of Black. This chemist ascertain- ascertained, that it existed in chalk, in common magnesia, edbyBiackancj^n common potash and soda; and that these substan- to deprive ... r. i • i r i • potash, so- ces, in their caustic state, were deprived ot their causticity, da and by combining with this air. As it became fixed in these their oaus- bodies, under certain circumstances, he gave it the name of ticity, by fixed air. After Black, Cavendish and Priestley made ex- with them, periments upon the air, and ascertained many of its proper- ties. Kier was the first to ascribe to it acid properties; which were afterwards proved to belong to it by Bergman and Fontana. Bergman adopted the opinion of Priestley, that it was an element of atmospheric air, and called it aerial acid. From its occasioning death when respired, Bewdley called it mephitic acid. By the labours of the chemists just mentioned, the more important properties of fixed air were ascertained. But the important question was yet to be answered; was it to be considered a compound or an elementary substance? BORACIC ACID. 215 Priestley and Bergman, at first, appear to have consi- Cha». 11. dered it an elementary substance; while some other che- Supposed, mists accounted it an acidifying principle. As soon as its Jg^™ compound nature was ascertained, and that oxygen wastobean' one of its constituents, the general belief was, that it was a elementary compound of oxygen and phlogiston; and when hydrogen8Ub8tance- (according to Kirwan) came to signify the same thing as phlogiston, of oxvgen and hydrogen. While the opinions of chemists were thus vacillating, as prove/Tby to the real nature of fixed air, Lavoisier succeeded in^™^. proving its constituents to be oxygen and carbon. It was posed of this chemist who gave it the name of carbonic acid, from the «JgJ ™* name of its base. Boron forms but one acid with oxygen; namely, boracic Boron acid. This acid is described in the following section. ^cid with oxy- gen. SECTION V. OF BORACIC ACID. Sedative or Narcotic Salt of Homberg. I. Boracic acid may be obtained by dissolving borax Boracic in hot water, filtering the solution, and afterwards precipi- Jjjj^y tating it, by means of sulphuric acid, added in excess. A crystallized precipitate falls, which, when washed, and dried on filtering paper, is boracic acid in the state of hydrate. II. Borax is a compound of boracic acid and soda. When sulphuric acid is added to its solution, it is decom- posed; sulphate of soda is formed, and boracic acid, preci- pitated. III. Boracic acid has heretofore been found only in bo-Exists only rax, in a state of combination with soda. IV. Boracic acid was discovered, in 1702, by Homberg, Discover- by whom it was called sedative or narcotic salt, while dis- h^^^ tilling a mixture of green vitriol and borax. Homberg was not aware of its real nature; and it was not until about 50 years afterwards, that its acid properties were ascertained, when it was named boracic acid. The discovery of its compound nature and constituents, by Gay-Lussac and Thenard, and Davy, has already been noticed under the head of boron. V. Boracic acid, as obtained by the process given in the Properties. first paragraph, is a solid, in the form of scales, of a silver- 216 ACIDS. B«»ok I. Division II Spec, grav, 1-479. Action of combusti- bles. Boracic acid, form- erly used in medi- cine. white colour. It has a greasv feel, and has some resemblance to spermaceti. Its taste is somev\hat sour at firsi; it then becomes bitterish and cooling, and at last agreeably sweet. After being heated to redness, however, it loses its sour taste. It has no smell; but the addition of sulphuric acid to it, produces a transient odour of musk. Vegetable blues are changed to red by its action. VI. It is somewhat less than one and a half times as heavy as water. It is perfectly fixed in the fire. Its melting point is at a red heat. By fusion, it is converted into a h.ird transparent glass, which becomes somewhat opaque by ex- posure to air. In this state, its specific gravity is 1*803. VII. Boiling water scarcely dissolves the -gJ^h part of its weight of boracic acid; and cold water, a still smaller quantity. When this solution is distilled in close vessels, part of the acid comes over with the water. Hence, al- though extremely fixed in the dry state, when in solution, it is somewhat volatile. VIII. None of the undecompounded supporters exert any action upon boracic acid. Of the undecompounded combustibles, the only ones, which appear capable of de- composing it, are potassium and sodium. IX. Boracic acid combines with many of the salifiable bases, forming salts called borates. X. The exact composition of boracic acid has not been well made out. The analyses of Gay Lussac and Davy are so discordant, as to forbid any confidence being placed in either. XI. Boracic acid was considered by its discoverer, Hom- berg, to be a very efficacious remedy in continued fevers; and, for a long time, it enjoyed considerable r.put ition, in France, for the cure of this class of diseases. At the present day, although an article of some power, it is very seldom employed. Phospho- Phosphorus forms three acids by combining with oxvgen; three acids namely, phosphoric acid, phosphorous acid, and h\po- vith oxy- phosphorous acid. These acids will be described in the three following sections. SECTION VI. OF PHOSPHORIC ACID. Phosphoric I. Phosphoric acid may be obtained bv the following obtained!' process: Mix the liquid, obtained by the slow combustion of phosphorus, with nitric acid, allow the mixture to stand PHOSPHORIC ACID. Q\1 for a few days, and then evaporate it to dryness. The dry Chap. II. mass i^ ])h isnhoric acid in the state of hydrate. II. When phosphorus is subjected to slow combustion, a liquid is formed, which is a mixture of phosphorous and phosphoric aci Is. When this liquid is mixed with nitric acid, the phosphorous acid is further oxidized at the ex- pense of the nitric ici'i; so that the whole becomes phos- phoric acid. The mixture is then exposed to a drying heat, in order to drive off any adhering nitric acid. III. The most abundant source in nature of phosphoric lt is ?">- acid is the bones ot animals. bones. IV. Phosphoric acid is a solid substance, sometimes Its proper- transparent, when it has considerable resemblance to glass. Ues" Ustu'lly, however, it is not perfectly clear, but possesses a degrtt of milkiness. It possesses a very sour taste, but no smell. It changes vegetable blues to a red colour. It does not possess corrosive properties. When exposed to the air, it absorbs moisture, and deliquesces into a thick, oil-like liquid. V. Phosphoric acid is a little more than two and two- sP|Cg8^av- third times as heavy as water. When exposed to a red heat, it melts into a transparent liquid, which, upon cooling, assumes the appearance of glass. In this state, it is known by the name of phosphoric glass: it is phosphoric acid, nearly, if not entirely, deprived of water. Phosphoric glass is about three times as heavy as water. VI. Phosphoric acid dissolves, very readily, in water. Soluble in When in the form of a dry acid, the solution takes place water- with a hissing noise, resembling that produced by red hot iron, when plunjred into water. In the form of glass, it is much less soluble. These solutions are attended by the evolution of some heat. The deliquesced acid is a solution of phosphoric acid. It is in this state that it is generally employed by chemists. Its specific gravity is 1*417. VII. Of the undecompounded combustibles, carbon, po- Action of tassium, sodium, iron, zinc and tin, are capable of decom- ^embustl" posing phosphoric acid; these bodies being oxidized, and phosphorus developed. The liquid acid oxidizes antimony, iron, manganese, zinc, lead, tin and bismuth; but some of these metals, very slowly. The oxidizement of the latter metals, takes place in consequence of the decomposition of water; as is evinced by the evolution of hydrogen. It has no action upon arsenic, nickel, cobalt, copper, silver, mer- cury, gold, or platinum. VIII. Phosphoric acid combines with most of the salifi- able bases, forming salts called phosr>Vat?*-.. Th^se salts will be described under the heads of their respective bases. 2 E 218 ACIbS Book I. IX. Phosphoric acid is composed of Div",ion11; Phosphorus 12—one atom. Composi- Oxygen 16—two atoms. tion. Giving 28 for the number represent- ing the weight of its atom.* Discovery X. Phosphoric acid had been for a long time known, of composi-before its composition was ascertained. Stahl considered it to be the same with hydrochloric (muriatic) acid; which acid, in combination with phlogiston, or the inflammable principle, he supposed to form phosphorus. Margraff ascer- tained that it was different from all other acids; but still it was considered to be a constituent in phosphorus. The composition of phosphoric acid was supposed to be perfectly well understood, when Lavoisier published his ex- periments on the acids; whereby he overturned the prevail- ing phlogistic doctrines, and demonstrated the true com- position of this acid. SECTION VII. OF PHOSPHOROUS ACID. Phospho- !• Phosphorous acid may be obtained by the following rous acid; process: Sublime phosphorus through pulverized perchloride how obtain-Q£ mcrcury (corrosive sublimate) contained in a glass tube: a chloride of phosphorus will be formed, and the mercury revived. Upon mixing this chloride with water, it will be converted into hydrochloric (muriatic) acid and phospho- rous acid, by combining with the constituents of this liquid. Evaporate the mixed acids, until the' whole become of the consistence of syrup: the evaporation will drive off the hy- drochloric acid; whereby the phosphorous acid will be ob- tained pure. Liquid ob- H» The acid, obtained by the slow combustion of phos- tained by phorus, was formerly called phosphorous acid. But this acid combustion xs now ascertained to be a compound of phosphoric acid, of phospho-and the acid, described, in the present section, as the phos- ed'acid1"'*" Parous 2LC'1^- Dulong, considering it to be composed of the two acids, just mentioned, united in a fixed proportion, has applied to it the name of phosphatic acid. III. Phosphorous acid was first obtained, in a pure state, by Sir H. Davy. * This composition is given on the authority of some late results, obtained by Sir H Davy. See Annals of Philosophy, p. 210. (March, 1819); or Sir H, Davy's paper, Phil. Trans. 1818. part II. HYPOPHOSPHOROUS ACID. 219 IV. Phosphorous acid is a solid substance, possessing a Chap. ii. very sour taste. It reddens vegetable blues, and has all the Properties characters of a strong acid. When heated strongly in the of phospho- open air, it catches fire and emits abundance of hydroguretrous aci of phosphorus (phosphuretted hydrogen); the residue being phosphoric acid. V. Phosphorous acid combines with some of the salifiable bases, forming salts called phosphites. VI. Phosphorous acid is composed of Its compo- Phosphorus 12—one atom. 8,Uon- Oxygen 8—one atom. Giving 20 for the number represent- ing the weight of its atom.* SECTION VIII. OP HYPOPHOSPHOROUS ACID. I. Hypophosphorous acid may be obtained by the follow- Hypophos- ing process: Allow phosphuret of barytes to remain in water, l»»'",(;',s as long as it gives out any gas. The water will be decom- obtained. posed; its hydrogen, by combining with part of the phos- phorus, gives rise to the formation of hydroguret of phos- phorus, the gas, which is extricated; while its oxygen com- bines in two proportions with the remaining phosphorus, so as to form the acid under description and phosphoric acid. Both these acids, as soon as formed, combine with the ba- rytes. Now phosphate of barytes is insoluble, while the hy- pophosphite dissolves in water: accordingly, upon filtering the liquid, the phosphate of barytes will be removed, and nothing will be left, but a solution of hypophosphite of ba- rytes. Add cautiously to this solution, sulphuric acid, as long as any precipitate should appear: this acid will form an insoluble compound with the barytes, and thereby libe- rate the hypophosphorous acid from combination. Separate the insoluble sulphate of barytes, and what remains will be a solution of hypophosphorous acid. II. Hypophosphorous acid was discovered in 1816 by Dulong. III. Hypophosphorous acid, in the state of solution, hasl.kprop61- a very sour taste, and possesses the property of reddening " This composition accords with a late result obtained by Sir H. Davy. See a notice of this chemist's paper (published in the Philosophical Transactions for 1811), in Thomson's Annals, p. 210. (March 1819). 220 ACIDS. Book I. vegetable blues. It absorbs oxvgen from the atmosphere. DivisionII. yf. cn , XpOSe(j to heat, it is totally decomposed; hydrogu- ret of phosphorus (phosphurettcd hydrogen) being evolved, and phosphoric acid remaining behind. It may be concen- trated by evaporation, so as to assume the form of a viscid liquid; but it cannot be made to crystallize. Composi- IV. According to Sir H. Davy, hypophosphorous acid is composed of Phosphorus 24—two atoms. Oxygen 8—one atom. Giving 32 for the number represent- ing the weight of its atom.* tion Arsenic Arsenic forms two acids by combining with oxvgen; name- fo ms two ly arsenic acid and arsenious acid. These acicis will be oxygen. described in the following sections. SECTION IX. OF ARSENIC ACID. Arsenic I* Arsenic ACID may be formed by the following process: aci', how dissolve three parts of arsenious acid (white oxide of ar- o tame . senic)in seVen parts of hydrochloric (muriatic) acid; and mix the solution with five parts of nitric acid: the arseniois acid becomes converted into arsenic acid, at the expense of the oxygen of the nitric acid. Evaporate the whole to dryness and then expose it to a red heat: the nitric and hydrochloric acids will be driven off, and the arsenic acid obtained pure. Its proper- II. Arsenic acid, when thus prepared, is a white sub- tie>- stance; poss- ssing scarcely any taste v/hen dry. It attracts moisture from the atmosphere. It is not volatile; but when exposed to a sufficient beat, it melts into a transparent liquid, which has the appearance of glass, when cold. If the heat b very strong, it gives out some oxygen, and is converted into arsenious acid, which rxhales the garlic odour. Spec grav. HI. Arsenic acid is about three and one-third times as 339. heavy as w tier. It dissolves slowly in six parts of cold water; hut instantlv in two parts of boiling water. In a state of solution, its taste is acrid, caustic and metallic. It may • For this composition, see \nnnlsof Philosophy, p. 210 (March 1819,) or Sir H. Davy's paper ')n th» compounds of phosphorus with oxygen, published in the Philosophical Transactions, part 11. (1818.) ARSENIOUS ACID. 221 be evaporated to the consistence of a syrup. In this form, Chap, ii. it contains half its weight of water. IV. Arsenic acid oxidizes arsenic, antimony, iron, nickel, its action cobalt, manganese, zinc, lead, tin, copper and bismuth; and on metaU- in a strong heat, mercury and silver. It does not act upon gold or platinum. V. Arsenic acid combines with many of the salifiable bases, and forms salts called arseniates. These salts will be described hereafter. VI. Arsenic acid is composed of Composi- * ah tion. Arsenic 4r>— Oxygen 24—three atoms. 70 VII. Arsenic acid is one of the roost virulent poisons Is a virulent know n. It is equally deleterious with arsenious acid. It is poia not used in medicine. SECTION X. OF ARSENIOUS ACID. Oxide of Arsenic of the Edinburgh College. Common names, Arsenic. White Arsenic. I. Arsenious acid may be formed by exposing metallic Arsenious arsenic to heat, in the open air. The metal sublimes in the Jgjj^ form of this acid. II. Ars« nious acid is obtained, for the purposes of com-How ob- merce and the arts, during the extraction of cobalt from its {J'en^ ores. These ores contain arsenic. During their roasting, way. arsenious acid, in an impure state, sublimes. The impure acid is afterwards purified by a subsequent sublimation, mixed with potash. III. Arsenious acid is a white, brittle, compact solid, of its proper* a vitreous appearance. Its taste is sharp and acrid, accompa-ties- nied bv an impression of sweetness. It changes vegetable blues to red. When heated, it emits fumes, which have a smell, resembling that of garlic. If a plate of copper be ex- posed to these fumes, it becomes white. IV. Arsenious acid is about three and three-fourths as Spec grav. heavy as water. When heated to the temperature of 283° 37a in the open air, it may be entirely sublimed. Hence, a very obvious means is afforded for the detection of adulterating substances, such as carbonate of lime (chalk) or sulphate of lime (gypsum). When subjected to heat, in close vessels, it melts into a pellucid glass, which soon becomes opaque by exposure to the air. 222 ACIDS Book I. V. Arsenious acid is soluble in 80 parts of cold water; Dmsion II but it dissolves in 15 parts of boiling water. In the state of Dissolves solution, the acid has an acrid taste, and changes vegetable m water, blues to a re(j coiour. When slowly evaporated, the acid falls in the form of crystals. VI. Arsenious acid combines with some of the salifiable bases, forming salts called arsenites. Some of these salts will be described hereafter. Itscompo- VII. Arsenious acid is composed of Arsenic 47—one atom. Oxygen 16—two atoms. Giving 63 for the number represent- ing the weight of its atom. The weight of an atom of arsenic, however, as deduced from this acid, is somewhat higher than when calculated from the arsenic acid. The proportions, in which arsenic combines with other bodies, do not accord well with the atomic theory. Arsenious VIII. Arsenious* acid is one of the most virulent poisons ient'poison. known. When taken into the stomach, or applied to a wounded part, it gives rise to a train of the most terrible symptoms, to which the human system is liable. Its anti- IX. A number of experiments have been made to ascertain dote" the best antidote for the arsenious acid. It has been found, that, of all the substances tried, liquid hydrosulphuric acid (sulphuretted hydrogen) promises to be the most effectual. Hydrosulphuric acid combines readily with arsenious acid, and forms a compound, which may be taken, in tolerably large doses, with impunity. Treatment When a case of poisoning by the arsenious acid is to be noisonine^treate<*J l^e ^rst steP *s to encourage vomiting, by giving by arsenic, large draughts of warm water, and by irritating the fauces with a feather. No emetic substances are to be used to produce this effect; as they add to the irritation. After the vomiting has ceased, it is next proper to wash out the sto- mach repeatedly with water, injected into that organ, through a gum elastic catheter, and returned again through the same instrument. After these measures have been carried fully into execution, liquid hydrosulphuric acid is to be adminis- tered in as large quantities as can be taken.* Uses of ar- X. Arsenic is sometimes exhibited in the form of a senious solution of arsenious acid. Four grains of the acid are dicbe. dissolved in a pint of water. The dose is a tablespoonful, gradually increasing. In this form, it has been exhibited in * For a full account of the arsenical poisons, see Nancrede's Abridgment of Orfila on Poisons; the work from which the above facts hare been taken. CHROMIC ACID. 223 cancer. It has also been used, both in powder and in solu- Chap. ii. tion, as an external application to cancerous sores. The arsenious acid, in substance, is given in the form of pills, in doses of about one-eighth of a grain. Chromium forms but one acid with oxygen; namely, chro- Chromium mic acid. This acid will be described in the following Jj(mwJ" Section. oxygen. SECTION XI. OF CHROMIC ACID. I. Chromic acid may be obtained by the following Chromic i> l- c •.. r P acid- how process: Koast a inixt re ot one part ot nitrate or potash obtained. (nitre) and two parts of the mineral called chromate of iron, in a hessian crucible. Treat the mass with water, until every thing soluble be taken up. By this management, part of the mineral becomes decomposed; the chromic acid of the decomposed portion combines with the potash of the nitrate of potash; and, in this state of combination being soluble, when the mass is treated with water, it is dissolved off, while the undissolved residue consists of oxide of iron and undecotnposed chromate. Dissolve off the oxide of iron by means of hydrochloric acid, and repeat the treat- ment already detailed, upon what remains. By these mea- sures the mineral will at last be totally decomposed. When this is effected, mix all the solutions of chromate of potash together; and saturate the liquid formed, with acetic acid, and then evaporate it, until it let fall crystals of chromate of potash. Dissolve these crystals in water, and add to the solution formed, chloride of barium (muriate of barytes): the chromic acid immediately falls in combination with ba- rytes. Wash the chromate of barytes, thus obtained; and, having dissolved it in nitric acid, add sulphuric acid cautiously to the solution: the sulphuric acid falls in com- bination with the barytes, while the chromic acid remains in solution along with the nitric acid. Remove the insoluble sulphate of barytes by the filter, and evaporate the remain- ing liquid to dryness, at a low red heat: this exposure to heat will drive off the greater part of the nitric acid. By Solutions and evaporations, repeated several times, the whole of the nitric acid may be removed. What remains will then be pure chromic acid. II. Chromic acid was discovered, in 1797, by Vauquelin, Discovery in chromate of lead (red lead ore of Siberia). 224 acids. ties. Book I. III. Chromic acid is a solid substance, of a deep red Division 11. coiour. jts taste js acrid^ sharp, and strongly metallic It Its proper- slowly absorbs moisture, when exposed to the air. When subjected to heat, it gives out oxygen gas, and is converted into protoxide (green oxide) of chromium. It is soluble in water, and may be obtained, from the solution, in crystals of a ruby-red colour. IV. Chromic acid combines with several of the salifiable bases, and forms salts called chromates. V. Chromic acid is composed of Chromium 28—one atom. Oxygen 24—three atoms. Giving 52 for the number represent- ing the weight of its atom. Composi- tion. Moiybde- Molybdenum forms two acids by comhining with oxygen; two adds" namely, molybdic acid >md molybdous acid. These acids with oxy- will be noticed in the two following sections. gen. SECTION XII. Molybdic acid; how obtained. Its proper- ties. OF MOLYBDIC ACID. I. Molybdic acid may be obtained bv the following process: Distil nitric acid off the mineral called molvbd na (sulphuret of molvbdenum) reduced to the state of powder: the nitric acid, by yielding up its ox\gen, will acidify the molybdenum, and, in part, the sulphur; so that after the distillation is completed, the mass obtained will consist of molybdic acid, mixed with sulphuric acid and some ad- hering nitric acid. By washing the mass carefully with water, the sulphuric and nitric acids will be removed; so that nothing will remain but pure molvbdic acid. II. Molvbdic acid was discovered, in 1778, bv Scheele. III. Molybdic acid is in the form of a white powder. When subjected to heat, in close vessels, it melts, and as- sumes the form of crystals upon cooling; but in open ves- sels, it sublimes in the form of brilliant yellow scales. IV. Mol)bdic acid is soluble in 90O parts of boiling water. The solution has a yellow colour, but no taste, ft is capable of reddening vegetable blues. The acid is precipi- tated, from the solution, by sulphuric, nitric, or hydrochloric acid. TUNGSTIC ACID. 225 V. Molybdic acid combines with some of the salifiable Chap, il bases, forming salts called molybdates. " VI. Molybdic acid is composed of Composi- Molybdenum 48—one atom. tion- Oxygen 24—-three atoms. Giving 72 for the number represent- ing the weight of its atom. SECTION XIII. OF MOLYBDOUS ACID. I. Molybdous acid may be obtained by the following Molybdous process: Triturate, in a porcelain mortar, a mixture of oneadd;h°w part of molybdenum, with two parts of molybdic acid, made into a pap with a little hot water, until the whole assume a blue colour. Then add eight or ten parts of water, and boil for a few minutes. Filter the liquid ob- tained, and evaporate it to dryness, at a heat not exceeding 120*. The dry mass will be molybdous acid. II. Molybdous acid is in the form of a blue powder, Its proper- soluble in water. It has the property of converting vegeta-t,e§- ble blues to red. It combines with salifiable bases, forming salts called molybdites. III. Molybdous acid is composed of Composi- Molybdenum 48—one atom. tIon- Oxygen 16—two atoms. Giving 64 for the number represent- ing the weight of its atom. Tungsten forms but one acid by combining with oxygen; Tungsten namely, tungstic acid. This acid will be described in the ^"tub.6 following section. oxygen. SECTION XIV. OF TUNGSTIC ACID. I. Tungstic acid may be obtained by the following Tungstic process: Boil three parts of hydrochloric (muriatic) acida?id'.hodv upon one part of the mineral, called wolfram (tungstate of iron) for several hours; and allow it to stand until it de- 2 F 226 ACIDS. Book i. posite a powder. Separate the powder by the filter, and msion II. dissolve it in ammonia. Evaporate the ammoniacal solution to dryness, and expose the drv mass to a red heat. The dry mass is now pure tungstic acid. It was discovered, in 1781, by Scheele. II. Tungstic acid is an insoluble yellow powder, incapa- ble of acting on vegetable blues. It, however, possesses the essential property of an acid, of forming salts with the sa- lifiable bases. III. Tungstic acid is composed of Tungsten 96—one atom. Oxygen 24—three atoms. Giving 120 for the number representing the weight of its atom. Its proper ties. Composi tion. Columbi- um forms one acid with oxy- gen. Columbium forms but one acid by combining with oxygen; namely, columbic acid. This acid will be noticed in the following section. SECTION XV. Columbic acid; how obtained. Its proper ties. Composi- tion. OF COLUMBIC ACID. I. Columbic acid may be formed by detonating a mixture of pulverized columbium and nitrate of potash (nitre), in a red-hot crucible. The nitric acid of the nitrate acidifies the columbium, and then is dissipated; so that the resulting mass is a mixture of columbic acid and potash. Dissolve the mass in water, and add, to the solution, hy- drochloric (muriatic) acid: this acid combines with the potash and remains in solution, while the columbic acid falls in the state of hydrate. II. Columbic acid was discovered, and its acid nature ascertained, by Hatchett, in 1801. III. Columbic acid is in the form of a white powder, insoluble in water, nitric or sulphuric acid. It combines with some of the salifiable bases, and forms salts called columbates. IV. Columbic acid is composed of Columbium 146—one atom. Oxygen 8—one atom. Giving 154 for the number repre- senting the weight of its atom. ANTIMONIOUS ACID 227 Chap. II. Antimony forms two acids by combining with oxvgen; Antimony namely, antimonic acid, and antimonious acid. These ^dsViith acids will be described in the two following sections. oxygen. SECTION XVI. OF ANTIMONIC ACID. I. Antimonic acid may be obtained by the following Antimonie process: Expose a mixture of one part of antimony in afl<1;. h°w powder, and six parts of nitrate of potash (nitre) for an hour, in a silver crucible, to as strong a heat as the vessel will bear: the mass formed will be found to be a mixture of antimonic acid, potash, and undecomposed nitrate of potash. Wash off the two latter with water; and digest the insoluble residue in hydrochloric (muriatic) acid, in order to be certain that all the potash is removed. After this treatment, dr\ it, and expose it to a sufficient heat to drive off all the water, which it may contain. What remains is pure antimonic acid. II. Antimonic acid is a straw-coloured powder. It is in-Its proper soluble in water, and does not redden vegetable blues, unless Ues" it be in the state of hydrate. When heated to redness, part of its oxygen is disengaged, and it is converted into antimonious acid. Its combinations with salifiable bases are called antimoniates. As yet no analysis of this acid has been made that can be depended upon. III. The mediciml preparation, formerly called diapho-Nature of retic antimony, the calcined antimony of the London col- diai)horetie • ' r • . , t • j • l. /-i-l -.antimony. lege, consists of antimonic acid, combined with one-nftn ot its weight of potash. It is formed pretty much in the manner just given for the acid itself; with these slight dif- ferences that the sulphuret of antimony, instead of the pure metal, is employed, and the product is not washed with hydrochloric acid, to separate adhering potash. SECTION XVII. OF ANTIMONIOUS ACID. (Formerly called Argentine Flowers of Antimony.) I. Antimonious acid may be obtained by dissolving Antimoni- antimony in nitric acid, evaporating the solution to dryness, ho^obtain- and exposing the dry mass to a red heat. It may be formed ed. 228 ACIDS Book I. also by subjecting protoxide of antimony to a red heat, or DivisionII. metallic antimony to a violent heat, in either case, combus- tion takes place, and antimonious acid sublimes in the form of crystals. When procured by sublimation, the acid was formerly called argentine flowers of antimony. Its proper- II. Antimonious acid is a powder, possessing a fine tie8, white colour and considerable lustre. It is insoluble in water, and dissolves with difficulty in acids. It requires a pretty high temperature to produce its fusion; but it is vo- latilized at a point comparatively low. Its combinations with salifiable bases are culled antimonites. It has not been analyzed with precision. CLASS III. ACIDS, WHOSE BASES FORM ACID COMPOUNDS BY COMBINING WITH HYDROGEN ONLY. Two acids Two acids only are known, belonging to this class: only belong namely, hydrofluoric acid, and hydrocyanic acid. The daw of"1'"1 former has an undecompounded base (fluorine), the latter acids. a compound base (cyanogen). These acids will be describ- ed in the two following sections. SECTION I. OF HYDROFLUORIC ACID. Usual chemical name, Fluoric Acid. Hydrofloo- I. Hydrofluoric acid may be obtained by the follow- ric acid; jng proceSs: Distil, with a gentle heat, from a leaden retort how obtain-.Rto a leaden receiveri any quantity of pure white fluor spar, which is a hydrofluate (fluate) of lime, with twice its weight of concentrated sulphuric acid. The receiver must be surrounded with a mixture of snow and salt, and the joinings of the apparatus, luted with clay. The product of the distillation will be hydrofluoric acid. Process ex- II. The mineral called fluor spar is a compound of hy- plained. drofluoric acid and lime. When it is mixed with sulphuric acid, it becomes decomposed; this acid combines with the lime, and the hydrofluoric acid is disengaged in the form of vapour, which afterwards condenses in the refrigerated receiver. Glass vessels could not be employed in the appa- ratus; since they would be corroded by the hydrofluoric HYDROFLUORIC ACID. 229 acid. The same objection does not apply to leaden vessels; Chap, il these not being acted upon by the acid. III. Hydrofluoric acid was first obtained pure, in 1808, This acid by Gay-liussac and Thenard; by whom the process, above Jf^"^ described, was invented. The acid, previously considered to Gay-Lus- be the acid of fluor spar, was ascertained by them to con-!?0*1"1, ... ■ 1 • j* I nenard. tain silica as an essential ingredient. IV. Hydrofluoric acid, at the temperature of 32°, is a its proper- colourless liquid. At the temperature of 60°, it still con- Ues- tinues a liquid. Its smell is similar to that of hydrochloric acid, but much stronger. When exposed to the open air, it fumes violently, and is entirely dissipated. It can only be preserved in metallic vessels; glass vessels are instantly corroded by it. It acts with great energy upon animal sub- stances of all kinds. When dropped upon the skin, it acts as a powerful escharotic. The fumes of the acid, when inhaled, prove exceedingly deleterious. It combines with a number of salifiable bases. The salts, which are thus formed, will be called hydrofluates. V. Hydrofluoric acid, when perfectly freed from water, Spec. gray. is very little heavier than this liquid; but, when diluted to 106, a certain extent, it suffers a condensation, and becomes one-fourth heavier than water. Its freezing point is not known. When exposed to a cold of — 4°, it does not con- geal. Its boiling point is not exactly ascertained; it is, how- ever, known to be very low. VI. Thenard has lately succeeded in combining this acid It may be with oxygen. The method of effecting it, is to add oxyhy- 0Xldlzed- drochloric acid to hydrofluate (fluate) of silver. The pro- ducts are chloride of silver, water, and oxyhydrofluoric acid. VII. When hydrofluoric acid is dropped into water, the Action of action is so violent, as to produce a noise, similar to that water« occasioned by plunging red-hot iron into the same liquid. On the other hand, when water is dropped into the acid, the former enters immediately into ebullition. The acid, even though very largely diluted, still retains its fuming property. VIII. When hydrofluoric acid is brought in contact with and of potassium, a violent action takes place; a white solid is PotaBS,um- formed, and a quantity of hydrogen gas, evolved. This re- sult is explained by supposing that the peculiar radical of hydrofluoric acid, which it is proposed to call fluorine, is combined with hydrogen in the formation of the acid itself; this radical is considered to combine with the potassium, while the hydrogen is evolved. IX. When silica, which has been precipitated from an This acid 230 ACIDS Book I. alkaline solution, is dried, and mixed, in a state of powder, D'VIMOnlL with pure hydrofluoric acid, a gaseous substance is instantly combines formed, which possesses the properties of an acid. This with uhca. gaseous acid is generally considered to be a compound of silica and hydrofluoric acid. It will be described hereafter. Its proba- X. It has already been mentioned, that chemists have sition. obtained the strongest evidences, that hydrofluoric acid is a compound of a peculiar radical and hydrogen.* This radical (fluorine) has not, indeed, been obtained in a separate state; but forming peculiar compounds with bo.lies already known. Hence, it must be different from every other form of matter, with which chemists are acquainted. SECTION II. OF HYDROCYANIC ACID. Usual chemical name, Prussic Acid. Scheele's I. Scheele's process for obtaining hydrocyanic acid is obttunh.g°r ^*e following"* Boil a mixture of ten parts ot Prussian blue hydrooya- in powder, five parts of peroxide of mercury, and thirty nic acid, parts of water, in a glass vessel, for some minutes. Filter the liquid obtained; and throw upon the matter, remaining on the filter, ten parts of hot water, to wash it completely. Pour the filtered liquid upon two and a half parts of clean iron filings, add at the same time one part of concentrated sulphuric acid, and mix the whole by agitation. Distil the mixture, as it now stands, at a gentle heat, until one-fourth of it has passed over into the receiver. The distilled pro- duct will be hydrocyanic acid. It is, however, rendered impure, generally, by admixture of a small portion of sul- phuric acid. By a re-distillation, off a portion of carbonate of lime, the sulphuric acid present will be retained, and the acid procured in a state of purity. * This is the proper place to inform the reader, why the name of the acid of fluor spar has been altered from fluoric to hydrofluoric. The probable composi- tion of the acid suggested the propriety of the prefix hydro. But this circumstance alone would not have been deemed sufficient to justify the alteration. What piincipally influenced me, were the suggestions of analogy. Both chlorine and iodine form acids by combining with oxygen or hydrogen indifferently; now is it not probable that the radical of the fluor spar acid may form an acid by combin- ing with oxygen? If such an acid compound should be discovered, it could not be called fluoric acid, unless the name of the arid, commonly so called, were changed to hydrofluoric So that it appears, that if the discovery, anticipated, should really be made, then the alteration, here proposed, would become abso- lutely necessary. On the otber hand, should it not be made, the new name will "•till be useful, by suggesting the probable composition of the acid. HYDROCYANIC ACID. 231 II. The explanation of Scheelc's process, if given in con- Cbap. II. fortuity with the light of recent discoveries, may be thus Schee,e»8 stated.' Prussian blue is a compound of peroxide of iron, process ex and a peculiar acid, composed of the elements of hydrocya- pai nic acid united to iron, called ferrocyanic acid. When this substance, in powder, is boiled with peroxide of mercury and water, it becomes decomposed; and its acid combines with the peroxid-, in such a manner, as to form cyanodide (commonly called prussiate) of mercury and peroxide of iron. The cyanodide of mercury being soluble, when the whole is placed upon a filter, it passes through; while the peroxide of iron, derived from the decomposition of the Prussian blue, as well as that formed in the manner just mentioned, is retained. When the solution of the cyanodide, in the next step of the process, is poured upon clean iron filings, and sulphuric acid added, the whole being shaken together; water becomes immediately decomposed, its hydrogen combines with the cyanogen of the cyanodide, forming hvdrocyanic acid, the mercury being revived; while its ox\gtn oxidizes the iron. The oxide of iron, thus formed, is then dissolved by the sulphuric acid; so that the resulting substances are mercury, and a liquid containing hydrocyanic acid and sulphate of iron in solution. Now hydrocyanic acid is volatile, which is not the case with sulphate of iron. Accordingly, when the liquid, containing them, is distilled; the acid is driven over into the receiver; while the sulphate is left behind. III. Gay-Lussac's method for obtaining hydrocyanic Ga^-Lus- acid is the following: Put a mixture of cyanodide (prus- ™*pri • • • i ii discovered, nature of Prussian blue. 1 his pigment was accidentally ,iuring the discovered, in 1760, by Diesbach, a preparer of colours, at analysis of •n t t«i • • i • r • •» Prussian Berlin. I his artist was desirous ot precipitating a particu- bjue, lar colour; and, for that purpose, borrowed some potash from Deppel, the chemist, who is known as the discoverer of an animal oil, formtrly much used in medicine. The potash, instead of producing the colour desired, threw down a beautiful blue powder. Upon investigating the cause of the unexpected production of this blue powder, it was ascertained that the potash emploved had been calcin- ed with blood, in some of Di ppel's processes. Guided by this information, Diesbach afterwards succeeded in con- triving a process, by which he could produce the blue pow- der at pleasure. This blue powder is Prussian blue. • Vauquelin's paper on cyanogen and hydrocyanic acid may be found in the AnnaUsde Cbimie, Vol. IX. (Oct 1818). All the Tacts given in the three last paragraphs are taken from bis paper. 2 G 234 ACIDS; Rook i. Prussian blue may be prepared by igniting, at a moderate 'n;heat, three parts of dried blood, and two parts of carbonate Prussian 0f potash (common potash). The mass is then dissolved in obtained* water, and the solution formed, precipitated by a solution of one part of sulphate of iron (green vitriol) and two parts of sulphate of alumina-and-potash (alum). The precipitate which is obtained is green; but, after being washed with diluted hydrochloric (muriatic) acid, it becomes of a beau- tiful blue colour. Its chemi- As Prussian blue constituted a very important pigment; cal nnure jt Decame a desideratum with chemists, to ascertain its ed by Mac- exact composition, Macquer was the first chemist of note, quer; and wno entered upon this investigation. He ascertained several facts, correctly, of it; but drew the erroneous conclusion, that it was composed of iron, supersaturated with phlogis- ton, or the hypothetical substance, whose presence was supposed to give combustibility to combustible substances. by Scheele, Scheele was the next chemist of eminence, who took up the rat-Vftsco- subject. He discovered a method, by which the colouring louring matter of the pigment, might be separated; and came to "h^h; t l^e conclusi°n» *^at lt; was a compound of ammonia and thename of charcoal. His process has already been given, in the begin- prussic ning of the present section. The colouring matter was soon after named prussic acid by Morveau; and it continued to be called by that name, until very lately. Berthollet repeated and extended the experiments of Scheele. This chemist came to the conclusion, that prus- sic acid does not contain ammonia ready formed, but is a triple compound of carbon, hydrogen, and azote. This conclusion was confirmed by Clouet, who found that prussic acid was formed, when ammonia is made to pass through a red-hot porcelain tube, filled with charcoal. Now, the ammonia must have been necessarily decom- posed, under such circumstances. Although the researches of Scheele and Berthollet had made manifest the constituents of prussic acid; yet no chemist was aware of the manner, in which they were combined. This discovery was reserved for Gay-Lussac. Manner in This chemist discovered, in 1815, that a peculiar gaseous which the fluid might be obtained, by exposing the substance, usually enuofthe ca"ea" prussiate of mercury, to a heat, somewhat under colouring redness. He ascertained that it possessed many curious unitldr a" properties, and that it was a compound of carbon and azote. certam'ed It is the cyanogen* gas, already noticed under the head of by Gay- Lussac; ———————————————————————— * Cyanogen is derived from xi/«»of, a blue colour, and yryno/iai to generate; it being the characteristic constituent in Prussian blue. HYDROCYANIC ACIB. 235 carbon. He discovered also, that this gas, combined with Chap.ii hydrogen, constitutes pure prussic acid; and, consequently, that the azote, in this acid, is not combined with hydro- n!)me gen, in the form of ammonia, but with carbon, forming changed cyanogen. This discovery, of the manner in which the con- [fc ^ by-*" stituents of the acid are combined, induced Gay-Lussac to drocyanic alter its name from prussic to hydrocyanic. acid- IX. Hydrocyanic acid, as obtained by Gay-Lussac's pro- Properties cess, is a colourless liquid, possessing a strong smell, simi- of hydrocy- lar to that of peach blossoms; and a sharp taste, which, at first, appears cooling, but afterwards produces a burning sensation in the mouth. At the temperature of 44$°, its specific gravity is 0*70. At the temperature of 64J°, it is 0*69. Its specific gravity, in a state of vapour, compared with common air, is 0*94. Its boiling point is at 79*7°, and its point of congelation, about 5°. X. Hydrocyanic acid vapour is inflammable. When fired by the electric spark with oxygen, the products are water, carbonic acid, and azote. Iodine exerts no action upon it: this supporter may be volatilized in the acid vapour, with- out undergoing any change. It is decomposed by chlorine, chlorocyanic acid being formed, and hydrogen, evolved. XI. When potassium or sodium is heated in hydrocyanic acid vapour, the latter becomes decomposed; cyanodide of potassium or sodium is formed, and hydrogen, evolved. In like manner, cyanodides are formed, when potash, soda, or barytes is heated in this acid gas. When passed over red- hot iron or platinum, the acid vapour is completely decom- posed into its ultimate constituents. XII. Hydrocyanic acid cannot be kept, for any length it decora- of time, without undergoing a total change. The pro- P°ses.«pon- ducts or its decomposition are ammonia, and a charry }nt0 ammo- matter, which is deposited. It does not appear capable of niaand combining with salifiable bases. When the attempt is made to produce this combination, a double decomposition takes place, and a cyanodide and water are formed. Some of these decompositions will be detailed under the heads of the salifiable bases. XIII. Hydrocyanic acid is composed of Itscompo- Azote 14—one atom. 1 « _« sition- Carbon 12-two atoms.) " Cyanogen 26-one atom. Hydrogen 1—one atom. Giving 27 for the number representing the weight of its atom. XIV. Hydrocyanic acid is a very deleterious, narcotic Its proper- poison. It has been employed of late, by Magendie, as at,es' ■?a 236 acids. Book I. remedy in pulmonary consumption. It does not appear ca- Pivision II. pablc of arresting the progress of this dreadful disc »se, when completely formed; but in some cases, yet in the incipient state, it has calmed the irritation, which gives rise to cough, and lessened expectoration in a remarkable de- gree. This acid, as a remedy in phthisis, has deservedly attracted the attention of practitioners in different countries; and is now undergoing such tri-ds, as will, no doubt, deter- mine, with precision, its medicinal powers. CL.ASS IV. ACIDS OF IRREGULAR CONSTITUTION. Acids of ir- This class of acids embraces the following compounds: regular con- stitution, L Chlorocarbonic Acid. 5. Chlorocyanic Acid. enumerat- 2 Chloriodic Acid. 6. Sulphocyanic Acid. ed. 3. Borofluoric \cid. „ 7. Ferrocyanic Acid. 4. Silicon1 none Acid. These acids will be described in the seven following sections. SECTION I. OF CHLOROCARBONIC ACID. Phosgene gas of J. Davy. Chlorocar- I. Chlorocarbonic acid may he obtained by the fol- bomcacid; lowing process: Into a flask, made as dry as possible and td, " exhausted of air, introduce equal volumes of chlorine gas and carbonic oxide gas, previously dried, as completely as possible, by being left in contact with fused chloride of calcium (muriate of lime). Expose the mixture to sunshine for about a quarter of an hour. The gases diminish to one- half their original bulk, the chlorine, at the same time, losing' its peculiar colour. The resulting gas is chloro- carbonic acid. It was discovered, in 1812, bv Dr. John Daw. Its proper- II. Chlorocarbonic acid is a gaseous fluid, invisible and tie8, elastic like common air. Its smell is very strong, and has been compared to that which would be produced by the mixture of the odours of chlorine and ammonia. Its fumes are more strong and suffocating than those of chlorine: th'-ir action on thi eves causes a painful sensation, and a rapid flow of tears. It changes vegetable blues to red, and CHLORIODIC ACID 237 has other properties of an acid. It is decomposed by water, Chap.II. and is converted into hydrochloric (muna.ic) acid and car- bonic acid. Its decomposition is produced also, when anti- mony, arsenic, zinc, or tin, is heated in it; the chlorine being absorbed by these metals, and carbonic oxide, left behind. It is not known to combine with any salifiable base but ammonia. III. Chlorocarbonic acid is composed of Itscompa. O.. -\ si tion. xyuen 8—one atom. 1 n , • • a * 4 ^> V _ > = Carbonic oxide 14—one atom. Carbon 6—one atom. J Chlorine 36—one atom. Giving 50 for the num- ber representing the weight of its atom. SECTION II. OF CHLORIODIC ACID. Chloruret of Iodine of Gay-Lussac. I. Chloriodic acid is formed, when a current of chlo- Chloriodic rine is made to pass into a vessel containing iodine. A ob'trined* combination takes place, and the compound formed is chlo- riodic acid. II. This acid was first discovered by Sir H. Davy; and afterwards b\ Gay-Lussac, without being aware of the pre- vious discovery of Davy. HI. Chloriodic acid is a solid substance; and, when Itsproper- neither of its constituents is in excess, it has a yellowties- colour. When, however, the iodine is in excess, it is red. It is very volatile, and deliquesces, when exposed to the open air. IV. Chloriodic acid dissolves in water. This solution is Dissolves a. colourless, if neither constituent of the acid be in excess; water- but if the chlorine predominates, it has a yellow colour. It gradually destroys vegetable colours, and possesses many of the properties of an acid. It is always decomposed, whenever the attempt is made to unite it with a salifiable base; water being decomposed, and hydrochloric (muriatic) and iodic acids, being formed. No analysis, which can be depended upon for accuracy, has been made of this acid. ACIDS. SECTION III. OF BOROFLUORIC ACID. Usual chemical name, Fluoboric Acid. Boroflua- I. Borofluoric acid may be obtained by applying the ric acid; heat of a lamp to a mixture, in a retort, of one part of ed, " finely pulverized fused boracic acid, two parts of fluor spar (hydrofluate of lime) and twelve parts of sulphuric acid. A gas is disengaged, which must be collected over mercury: this gas is borofluoric acid. It was discovered, in 1808, by Gay-Lussac and Thenard. its proper- H« Borofluoric acid is a gaseous fluid, invisible and ties. elastic like common air. Its taste is exceedingly acid, and its smell resembles that of hydrochloric (muriatic) acid. It instantly changes vegetable blues to red. It may be passed over red-hot iron, without undergoing decomposition. It Spec grav. is about two and one-third times as heavy as common air. 3'37- It combines with salifiable bases, and forms salts which will be called borofluates. Absorbed, III. Water absorbs 700 times its volume of borofluoric m large acj^ ~a_ anj becomes nearly four-fifths heavier. Liquid amount, by «? • • 1 i • 1 • i r • 1 water. borofluoric acid, which is thus formed, has a certain degree of viscidity; in which circumstance, as well as in requiring a high temperature for ebullition, it resembles liquid sul- phuric acid. When heated, it emits fumes, until about one- fifth of the acid gas has separated; after which, the further increase of heat produces no effect. It agrees also with liquid sulphuric acid, in the manner in which it acts upon animal and vegetable substances; it converting them into charcoal. IV. When potassium or sodium is heated in borofluoric acid gas; these metals undergo combustion, and the acid is decomposed. Fluoride of potassium or of sodium is form- ed, intermixed with boron. When either of these fluorides is thrown into water, this liquid is decomposed, and hydro- fluate (fluate) of potash or soda is formed. Hence, it is evident that borofluoric acid is a compound of boron and fluorine; but united in what proportional quantities is not known. 238 Book I. Division II. SILICOFLUORIC ACID. 239 Chap. II. SECTION IV. OF SUJCOFLUORIC ACID. Usual chemical names, Silicated Fluoric Acid.—Fluosilicic Acid. The Fluoric Acid of Scheele. I. Silicofluoric acid may be obtained by exposing siiicofluo- equal parts of pulverized fluor spar and glass, made into a ™c ac»d:. *.. ir. • -j »i 1. * • a howobtam- paste with sulphuric acid, to a gentle heat, in a retort. Aed. gas is extricated in abundance, which must be collected over mercury. This gas is silicofluoric acid. II. As the history of this acid gas is very much connect- Account ed with the researches, which have been made by chemists, ^h*h™" from time to time, into the nature of fluor spar, frequently which led called Derbyshire spar, it is proper to give a short accountt0 the dL?r of them. its true na- Fluor spar was formerly used as a flux to facilitate theture- fusion of ores; and it is from this circumstance that it has its name. Nothing had been ascertained of its chemical nature, except that it had the power, under certain circum- stances, of corroding glass, a fact which was known, at Nuremberg, as early as the year 1670, until Margraff pub- lished a dissertation on it, in the Berlin Transactions for 1768. This chemist ascertained, that sulphuric acid was not one of its ingredients, as had been previously conjec- tured; and procured, by the action of this acid upon it, a white sublimate, which he supposed to be the fluor spar itself, undecomposed. He observed, also, that the retort, in which the experiment had been made, was corroded into holes in several places. In 1771, three years after the publication of Margraff; Scheele published a set of experiments upon fluor spar. This chemist resolved it into lime, and a peculiar acid, before that time unknown, to which he gave the name of fluoric acid, from the name of the spar itself. He examined the acid, which he obtained, and noted many of its proper- ties. The subject was soon after pursued by Priestley. This chemist demonstrated that the acid, obtained by Scheele, was a gaseous fluid, and added considerably to the knowledge previously possessed with regard to its nature. Although the fluoric acid of Scheele remained an unde- compounded substance, contrary to the analogy of the other acids; yet it was considered to be perfectly well ascertained, that it was the acid existing in fluor spar. This •pinion was universally held, when Weigleb, Bucholz, and 240 ACIDS Book I. Meyer successivelv proved, that the fluoric acid of Scheele Division II. contained siiica, whieh did not exist, n. cessarily, in the acid of fluor spar; but entered into combination with it, in consequence of its extrication in glass vessels; such vessels being always, in part, dissolved by its action. In 1808, Gay-Lussac and Thenard discovered, that, by distilling fluor spar containing no silica, with concentrated Sulphuric acid, in leaden vessels, an acid is obtained, very different from the fluoric acid of Scheele, in which silica is not a constituent. In 1812, Dr. John Davy ascertained, that the fluoric acid of Scheele contained silica, not as an accidental, but as an essential constituent; and th t the acid of Scheele was compos-d of the fluoric acid of Gay-Lussac ar>d Thenard, and silica, united in an invariable proportion. Hence, therefore, Seheele did not discover tht acid of fluor spar; but the acid, which he obtained, is a peculiar one, com- posed of the true acid of this spar and silica. It is this pe- culiar acid, which furnishes the subject of the present section. The true acid of fluor spur, commonly called fluoric acid, has already been described, under the name of h> drofluoric acid. Properties III. Silicofluoric acid is a gaseous fluid, invisible and of sihcoflu- eiastic lite common air. It possesses a very sour taste, and a smell, similar to that of hydrochloric (muriatic) acid. It changes vegetable blues to red. When allowed to escape into the open air, it assumes the form of white fumes, ow- Spec. grav. ing to its combination with moisture. It is about three and 3S7' a half times as heavy as common air. It is absorbed by water, which takes up 263 times its volume of the acid gas; but it is decomposed, md deposites its silica. Itsproba- IV. As to the composition of silicofluoric acid, the ble compo-most usual opinion is, that it is a compound of h\ dro- fluoric (fluoric) acid and silica. If this should turn out to be its true composition; then, according to the nomen- clature adopted in this work, it should be called silicated hydrofluoric acid. Sir H. Davy, however, supposes, from analogy, that it is composed of fluorine and silicum.* * The reader has, no doubt, noticed, that I have taken the liberty of proposing new names for the acids last described. I purposely omitted any explanation on the subject, until both acids were described; in order that one notice of the alte- rations might serve for both. As I had rejected the opinion that silica is an acid, or silicum acidifiable, I could not give, to the names of these substances, the characteristic termination of an acid Hence, it could not be proper to call the acid, here denominated silico- fluoric acid, by the name of fluosilicic acid, or the salts formed by it, fiuosilicates. These latter salts have, therefore, been called silicofluates, which is a better term; as it has some conformity with tr^i • old name, fluates. The discoverers of borofluoric acid (Gay-Lussac 8c Thenard) have given to it, the name of fluoboric CHLOROCYANIC ACID 241 8hap II. SECTION V. OF CHLOROCYANIC ACID. Oxyprussic Acid of Berthollet. I. Chlorocyanic acid may be obtained by the follow-Chiorocya- incr process: Pass a current of chlorine through a solution £1C ac'cl:. r i ■ • • i • -i l i i- i howobtain- of hydrocyanic acid, in water, until the latter discolours ed. indigo dissolved in sulphuric acid. Agitate the liquid obtained with mercury, in order to remove any excess of chlorine. The liquid is now a solution of chlorocyanic acid. To separate it in a pure state, a glass cylinder is filled, two-thirds with mercurv, and the remainder with this li- quid, and then inverted in a basin of mercury. The cylin- der, thus disposed, is put under the receiver of an air-pump, and the air exhausted, until the whole of the mercury and liquid, contained in the cylinder, sinks into the basin; the space in the cylinder, being filled with chlorocyanic acid vapour. Upon letting the air into the receiver again; the mercury rises in the cylinder, and the chlorocyanic vapour becomes condensed into a liquid, and is thus obtained pure. II. Berthollet was the first chemist who formed this Discovery. acid; but he was led to believe, that it was a compound of oxygen and prussic (hydrocyanic) acid. Its real nature was ascertained, in 1815, by Gay-Lussac, who obtained it, in a separate state, by the process just given. III. Chlorocyanic acid is a colourless liquid, possessing its proper- a peculiar odour. Its vapour, when drawn into the nose,Ue8, stimulates the Sneiderian membrane, and occasions a flow of tears. It is capable of combining wTith water. It is not known to combine with any of the salifiable bases. IV. Chlorocyanic acid is composed of Azote 14—one atom. 1 n ac . _ n , not sidered it to be a compound ot protoxide ot iron and hy- correctly drocyanic (prussic) acid. Dr. Thomson, however, fromknown- theoretical grounds, considered it, in his system of chemis- try, a compound of iron and cyanogen, and called it ferro- cyanic acid. This latter chemist has recently published a paper upon the triple prussiate of potash,* in the course of which he examines Porrett's acid, and concludes that it is a compound of hydrocyanic acid and iron; he, however, was not enabled to reconcile this composition with the atomic • Annals of Philosophy XII. 102. 246 ACIDS. Book I. theory. In consequence of the investigations of Thomson; DivisionII. porrett was led to re-examine the same triple prussiate; and the results which he obtained, induced him to believe that the ferruretted acid contains metallic iron, as Dr. Thomson first supposed, combined with the elements of two atoms of hydrocyanic acid —an atom of azote. Or to state the composition fully, he considers the ferruretted acid to be composed of Carbon 24—four atoms. Azote 14—one atom. Hydrogen 2—two atoms. Iron 28—one atom. 68 The composition, which Porrett assigns to the ferruret- ted acid gives an equivalent number for it, which acccords very well with that deduced from the ferrocyanates of bary- tes and potash.* Although it is doubtful in what way the constituents of this acid are united; yet it appears to be perfectly well as- certained that hydrogen is one of its ingredients. Of course Dr. Thomson's name, ferrocyanic acid, is not correctly formed. Notwithstanding, this appellation is retained, in preference to Porrett's name, which has the disadvantage of being long and harsh-sounding. As the ferrocyanic acid, as well as the acid last described, contains hydrogen, perhaps these compounds should have been classed as acids, whose bases form acid compounds with hydrogen only. But as their chemical nature is but imperfectly understood, and as yet a subject of controversy, it appeared most expedient to place them amongst the acids of irregular constitution. CLASS V. ACIDS IN WHICH OXYGEN AND HYDROGEN ARE BOTH PRESENT. Fifth class Acids belonging to this class are the following: of acids 1. Uric Acid. enumerat- 2. Purpuric Acid. ed. 3. Gallic Acid. 4. Formic Acid. 5. Oxalic Acid. 6. Sorbic Acid. 7. Succinic Acid. 8. Acetic Acid. 9. Tartaric Acid. 17. Pyrotartaric Acid IVIoroxylic Acid. 10. Benzoic Acid. 18 11. Saclactic Acid. 19. Suberic Acid. 12. Citric Acid. 20. Laccic Acid. 13. Mellitic Acid. 21. Kinic Acid. 14. Cam phone Acid. 22. Zumic Acid. 15. Malic Acid. 23. Boletic Acid. 16. Lactic Acid. * Annals of Philosophy XII. 215. (Sept. 1818.) URIC ACID. 247 These acids will be described, in the order in which they Chap.ii. have been enumerated, in the following sections. SECTION I. OF URIC ACID. (Formerly called Lithic Acid.) I. Uric acid may be obtained by the following process: Uric acid; dissolve calculi, which are composed principally of thishow obtam- acid, in liquid potash, and precipitate the solution by means of hydrochloric (muriatic) acid. The precipitate, after being washed with a little ammonia to separate adhering acid, and afterwards with warm water, is pure uric acid. II. Certain urinary calculi are composed almost entirely of uric acid. They are known by certain external marks, familiar to the chemist. When they are dissolved in liquid potash, a solution of urate of potash becomes formed. When hydrochloric acid is added to this solution, it com- bines with the potash and remains in solution, while the uric acid is precipitated. III. Uric acid was discovered in 1776 by Scheele, who Its history. described many of its properties. The results of this chemist were afterwards confirmed by Bergman. The French chemists soon after gave it the name of lithic acid. In 1797, Dr. Wollaston published a paper on the calculous concretions, and added much to what was previously known respecting this acid. The following year Dr. Pearson published a paper on the same subject, and enlarged considerably the previous knowledge of its nature. This chemist proposed to alter the name of the acid, from lithic to uric, a change which is now almost universally adopted. Fourcroy and Vauquelin next examined the acid, in their treatise on uri- nary calculi. Lastly Dr. Henry, in 1807, published a very full account of the uric acid. IV. Uric acid is a white powder, possessing a harsh, but Its proper- not a gritty feel. It is destitute of taste or smell. It changes ties- infusion of litmus to a red colour. It dissolves in 1720 times its weight of water, at the temperature of 60°; and in 1150 times its weight of boiling water. As the boiling solution cools, the acid falls in the form of minute crystals. When subjected to distillation, there come over into the receiver, 1. a drop or two of water, holding carbonate of ammonia in solution; 2. dry carbonate of ammonia; 3. a substance, which has acid properties, and which has been distinguished by the name of acid sublimate; and there remains in the retort, a coal amounting, in weight, to about one-sixth of the acid employed. 248 acids Book I. V. Uric acid combines with salifiable bases, and forms Division n.sahs calkd urates< Itscompo- VI. According to an analysis lately made by Dr. Prout, sition. urjc acid j5 composed of ing its atom. Azote Carbon Hydrogen Oxygen Giving * 14—one atom. 12—two atoms. 1—one atom. 8—one atom. 35 for the numb SECTION II. Purpuric acid; form> ed by the action of nitrie acid upon uric acid. How ob- tained in a separate state. Its proper ties. OF PURPURIC ACID. I. Ever since the discovery of uric acid, it had been ob- served by chemists, that this acid, when treated with diluted nitric acid, forms a solution of a beautiful pink colour. This solution has lately been examined by Dr. Prout, who has ascertained that it is composed of a peculiar acid prin- ciple united to ammonia. For the acid principle, Dr. Wol- laston has proposed the name of purpuric acid, which is adopted by Dr. Prout. It is this newly discovered acid, which furnishes the subject of the present section. II. Dr. Prout obtained the purpuric acid in a separate state by the following process: He digested pure uric acid in dilute nitric acid; whereby an effervescence took place, and the uric acid was dissolved. He next neutralized the excess of nitric acid with ammonia, and concentrated the whole by slow evaporation: as the evaporation proceeded, purpurate of ammonia separated in dark-red granular crystals. By treating the purpurate with sulphuric or hydrochloric (mu- riatic) acid, the ammonia was separated, and the purpuric acid fell in the form of a precipitate. III. Purpuric acid is in the form of a very fine powder, of a slightly yellowish or cream colour. Its specific gravity is considerably above that of water. It is verv sparingly soluble in water, and perfectly insoluble in alcohol or ether. It does not affect the colour of litmus paper, which Dr. Prout supposes to be owing to its sparing solubility. It does not deliquesce in the air, but acquires a purplish tint, which is owing to the spontaneous formation of ammonia. • Annals of Philosophy XL 355. GALLIC ACID. 249 When exposed to heat, it neither melts nor sublimes, but Chap, ii. becomes purple and burns away gradually, without exhaling any remarkable odour. When heated in close vessels, the products are carbonate of ammonia, some hydrocyanic (prussic) acid, a little liquid having an oily appearance, and charcoal. It combines with a number of salifiable bases, with which it forms peculiar salts, proposed to be called purpurates. IV. According to Dr. Prout, purpuric acid is composed CompoJi- of «°* Azote 14—one atom. Carbon 12—two atoms. Hydrogen 2—two atoms. Oxygen 16—two atoms. Giving 44 for the number represent- ing its atom.* Upon comparing purpuric acid with uric acid, it is per- ceived that they agree as to constituents. The only differ- ence between them consists in the presence of an atom of hydrogen and of oxygen in the former, not to be found in the latter. The uric and purpuric acids are the only acid compounds of the fifth class which contain azote. All the remaining acids, belonging here, are ternary combinations of carbon, hydrogen and oxygen. SECTION III. OF GALLICf ACID. I. Gallic acid may be obtained by exposing pulverized Gallic acid; how "L ed. nutgalls, in a large retort, to a heat, cautiously and gradual h ly raised. A substance sublimes in a crystallized form, which is pure gallic acid. This process, however, does not succeed without a great deal of precaution; for if the heat be not withdrawn soon enough, a portion of oil is driven over also, which dissolves the crystals, which may have previously formed. The following method is more easily managed. • The above facts respecting purpuric acid have been taken from Dr. Prout's paper on an acid principle prepared from uric acid.— Phil. Trans. 1818. part 11. p. 420. f r'rom gal/a, the Latin name for the oak-gall, the vegetable substance frnm which gallic acid was first obtained. 2 I 250 ACIDS. Book I. Division II Another process. Properties of gallic acid. Its compo- sition. II. Expose an infusion of nutgalls, for a long time, to the air, removing from time to time the mouldy skin, which will form upon its surface. In consequence of the exposure, the infusion will form a quantity of sediment. Separate this sediment, and, after having washed it in cold water, dis- solve it in hot water, and then filter the solution formed and evaporate it gradually. Crystals of gallic acid will gradually be formed, which are rendered impure by ad- mixture of tannin.* To separate the tannin, make the crys- tals perfectly dry, and expose them to a gentle heat, in a glass vessel: the gallic acid alone sublimes, while the tannin remains behind. III. Gallic acid has been found in a number of vegetable substances; but far most abundantly in nutgalls, from which it takes its name. Its properties were first examined by the Dijon academicians, in 1777. IV. Gallic acid is in the form of transparent crystals. It has a sour taste, mixed with a degree of astringency. When heated, it emits a peculiar, but rather unpleasant, aromatic odour. It is not altered by exposure to the air. It is a very important re-agent for the detection of metallic bodies. It is soluble in twelve parts of cold water, and in one and a half parts of boiling water. When the solution is exposed to the air, it assumes a brown colour, its surface becomes covered with mouldiness, and the acid is destroyed. It combines but imperfectly with salifiable bases. The salts which it forms are called gallates. V. According to an analysis of Berzelius, reduced to numbers, which best accord with the atomic theory, gallic acid is composed of Carbon 11 80—two atoms nearly. Hydrogen 1*03—one atom, very nearly. Oxygen 800—one atom. Supposing this acid to contain exactly the number of atoms, which seem to be indicated by the above numbers, then the number representing the weight of an atom of gallic acid would be 21. Formic acid; how obtained. SECTION IV. OF FORMICf ACID. I. Formic acid may be obtained by the following pro- cess: Infuse any quantity of red ants in three times their * Tannin is a peculiar substance to be described hereafter. f Derived from the Latin word formica, an ant. OXALIC ACID. 251 weight of water. Distil the infusion from a silver vessel, Chap. ii. as long as any liquid comes over, free from a burnt smell. " Saturate the liquid obtained with carbonate of potash, and evaporate to dryness. Mix the dried mass with sulphuric acid diluted with half its weight of water, sufficient to sa- turate the potash. Now distil to dryness. The liquid ob- tained, after being subjected to a second distillation to separate adhering sulphuric acid, is pure formic acid. II. That an acid liquor could be obtained from the red Its disco- ant was noticed as early as the year 1671. Very little,very' however, was known respecting its nature, before Margraff published a dissertation upon it in 1749. This chemist may, therefore, be considered as the discoverer of formic acid. III. Formic acid is a liquid, possessing a sharp sour Its proper; taste. It is not capable of crystallizing, even when subject-t,e8, ed to artificial cold. Its combinations with salifiable bases are called formates. In specific gravity, it is a little more Spec. grav. than one-tenth heavier than water. 1'11" IV. According to an analysis, performed by Berzelius, its compo- given in proportional numbers, which best accord with thesition- atomic theory, formic acid is composed of Carbon 12*01—two atoms, very nearly. Hydrogen 1 •05—one atom, nearly. Oxygen 24*00—three atoms. Supposing this acid to contain exactly the number of atoms, which appear to be indicated by Berzelius' analysis, then the number representing its atom would be 37. SECTION V. OF OXALIC* ACID. (Formerly called Acid of Sugar.—Saccharine Acid.) I. Oxalic acid may be obtained by the following pro-Oxalic acid; cess: Pour nitric acid upon a quantity of sugar in powder, h«wohtain- contained in a retort, and expose the whole to a moderate heat. An effervescence immediately takes place, accom- panied by the emission of a large quantity of deutoxide of azote (nitrous gas) and carbonic acid, and the sugar disap- pears. As soon as the effervescence is over, as the liquid in the retort cools, a number of crystals are found to form. These crystals consist of oxalic acid in the state of hydrate. • Derived from the Latin word oxatis, sorrel: because the oxalic acid has been detected, ready formed, in a species of sorrel, called oxalis acetosella. 252 ACIDS. Book i. This acid was discovered by Bergman and Scheele. A Division II. niimher 0f substances yield it besides sugar. It may be formed by the action of nitric acid upon gum, alcohol, honey, and a great variety of animal and vegetable sub- stances. Its proper- II. Oxalic acid, obtained by the process just given, is in t,eB# the form of transparent crystals, possessing a fine white co- lour and considerable lustre. They have an acid taste, and redden all vegetable blues except indigo. When cautiously exposed to heat, in a sand bath, they lose their water of crystallization, and fall to powder. When in the form of crystals, the acid is not altered by exposure to air; but when subjected to a considerable heat, it emits a smoke, which affects disagreeably the nose and eyes, and becomes partially decomposed. When taken into the stomach, in considerable quantities, it acts as an energetic poison. In the amount of an ounce, it proves almost immediately fatal. III. Crystallized oxalic acid is soluble in twice its weight of water, at the temperature of 65*7°, and in its own weight of boiling water. The solution, when concentrated, has a very acrid taste; but when sufficiently diluted, it becomes agreeably sour. Oxalic acid dissolves in h\ drochloric (mu- riatic) acid without decomposition. It is partly decomposed by sulphuric acid when assisted by heat, and a portion of charcoal formed. It is totally decomposed by nitric acid, being converted into water and carbonic acid. Products of IV. The combinations of oxalic acid with salifiable bases its decom- are called oxalates. When these salts, in a dry state, are posrion y eXpOSCCj to a re(j heat, their acid becomes totally decom- posed, and its constituents recombine so as to form five new substances; namely, water, carbonic acid, carbonic oxide, bihydroguret of carbon (carburetted hydrogen) and charcoal. Hence its constituents are carbon, hydrogen, and oxygen. Its compo- V* According to an analysis, performed by Gay-Lussac sition. and Thenard, calculated in proportional numbers, which best accord with the atomic theory, oxalic acid is com- posed of Carbon 12*05—two atoms, very nearly. Hydrogen 1»20—one atom, nearly. Oxygen 32*0< —four atoms. Supposing this acid to contain exactly the number of atoms, which appear to be indicated by the above analysis, then the number representing its atom would be 45. SORBIC ACID 253 Ghap. II. SECTION VI. OF SORBIC* ACID. I. Sorbic acid was discovered, in 1815, by Donovan, Sorbic acid; in the expressed juice of the berries of the mountain ash ,ts ,,lsc0" (pyrus aucuparia). Its peculiar nature has since been amply confirmed by Vauquelin and Braconnot. II. The outline of Donovan's process for obtaining thisPrepara- acid is to saturate the expressed juice of the berries withtU)n* acetate of lead (sugar of lead), whereby a sorbate of lead becomes formed. This sorbate is then partially decompos- ed by sulphuric acid, and the lead, contained in the resulting supersorbate, is thrown down by means of a current of hy- drosulphuric acid (sulphuretted hydrogen). III. Sorbic acid, when first obtained, is a liquid, colour-Tts proper- less and inodorous, and possessing an intensely sour taste. Ues" When evaporated to the consistence of a syrup, it forms a mass of a crystalline structure, which still contains a con- siderable quantity of water, and deliquesces in a moist atmosphere. With acetate of lead, it gives a precipitate, white and flocculent at first, but afterwards becoming of a crystalline appearance. By the action of nitric acid, it is converted into oxalic acid; from which circumstance Vau- quelin concludes, that it bears considerable analogy to malic acid. This chemist also suggests that sorbic acid, being co- lourless and inodorous and possessing an agreeable taste, might be employed, in medicine and the arts, as a substitute for tartaric and citric acids. IV. According to an analysis performed by Vauquelin, Composi reduced to numbers, which best accord with the atomicU0D" theory, sorbic acid is composed of Carbon 11*76—two atoms, nearly. Hydrogen 7*00—seven atoms. Oxygen 22*89—three atoms, most nearly. Supposing this acid to contain exactly two atoms of carbon, and three atoms of oxygen, then the number representing its atom would be 43.f * From sorbus, the old generic name of the plant from which this acid is ob- tained. f The greater part of the facts, contained in this section, are taken from abstracts of the papers of Vauquelin and Braconnot, contained in the Annals of Philosophy, Vol. Xll. (Oct. 1818.) p. 290. ct seq. 254 acids. Book I. Division II SECTION VII. Succinic acid; how obtained. Kurnished by amber only. Properties of succinic acid. Its compo- sition. OF SUCCINIC1' ACID. Common name, Salt of Amber. I. Succinic acid may be obtained by the following process: Fill a glass retort, half full, with a mixture of am- ber reduced to powder, and fine sand. The object of the sand is to prevent the amber from running into a mass, when exposed to heat. Distil the mixture, in a sand bath, at a heat gradually increased* A substance sublimes in the neck of the retort. This substance is succinic acid, rendered impure by an oily substance, called oil of amber, which is also a product of the distillation. The acid may be obtained pure by dissolving the sublimate in water, filtering the so- lution formed, and setting it aside for spontaneous evapo- ration. Crystals will form in the solution, which consist of succinic acid. II. Amber is the only substance, which is known to yield succinic acid. It is a brown, transparent, inflammable body, susceptible of polish, found at some depth in the earth, and on the sea coasts of several countries. It had long been known that a volatile substance could be obtained from it by dis- tillation; but it was Boyle, who first remarked that this sub- stance had acid properties. Its chemical nature, however, was first ascertained experimentally by Pott. III. Succinic acid, when obtained by the process just given, is in the form of transparent, white, shining crystals, possessing an acid taste. It is capable of reddening some vegetable blues. It does not possess corrosive properties. At the heat of a sand bath, it melts and sublimes, but not without suffering a partial decomposition. It is soluble in either sulphuric or nitric acid, without decomposition. Hy- drochloric (muriatic) acid, when cold, has very little effect upon it. It dissolves in 96 times its weight of water at the temperature of 50°, and in twice its weight of boiling water. Its combinations with salifiable bases are called succinates. IV. According to an analysis, performed by Berzelius, given in numbers, which best accord with the atomic theory, succinic acid is composed of Carbon y 24*0—four atoms. Hydrogen 2*2—two atoms, nearly. Oxygen 24*0—three atoms. • Derived from the Latin word succinum, amber. ACETIC ACID. 255 Supposing there existed, in this acid, hydrogen exactly Chap. ii. equivalent to two atoms, then the number representing an "~ atom of succinic acid would be 50. V. Succinic acid is never used in medicine, but oil of amber is sometimes employed as an antispasmodic. SECTION VIII. OF ACETIC- ACID. (Radical vinegar.) I. Acetic acid may be obtained by distilling acetate of Acetic acidj copper (verdigris) at a heat, gradually increased to the h°w obtoin- point ol redness. A liquid is driven over into the receiver, which has a greenish tinge, owing to the presence of copper. By a re-distillation, the copper is separated, and a colour- less liquid obtained, which constitutes a very concentrated solution of acetic acid. II. It may be obtained, in the form of crystals, by distil- ling a mixture of three parts of acetate of potash, and four parts of sulphuric acid. A liquid is driven over into the receiver, which is a very concentrated solution of acetic acid, mixed with a portion of sulphuric acid. To separate the latter acid, distil the liquid, off acetate of barytes: the sulphuric acid is retained, and the liquid, which comes over, forms crystals of pure acetic acid. III. Acetic acid constitutes the basis of the well known It is the liquid called vinegar. In vinegar, however, it is largelyacid of Vl" diluted with water, and mixed with bitartrate of potashneSar (tartar), a portion of alcohol, several vegetable acids, colour- ing matter and a portion of mucilage. Vinegar is made by exposing wine, beer, or similar liquids to the contact of the atmosphere, at a temperature at least as high as 80°, mixed with some substance to act as a ferment. When vinegar is distilled, it loses many of its impurities, and takes the name of distilled vinegar, or acetous acid. Vinegar, when thus altered, was formerly supposed to contain an acid, dif- fering from the acetic acid, in containing less oxygen; and hence it got the name of acetous acid. But it has been as- certained that there is no other difference, between acetous and aceticacid, than in the quantity of water which they con- tain; the acetous acid being, in fact, acetic acid, diluted to a certain extent. Properly speaking, therefore, acetous acid • Derived from acetum, the Latin word signifying vinegar. 256 ACIDS Book I. does not exist. As vinegar is a very important substance, Division II. t^h jn the arts ancj jn mctiicine> it may be proper to notice its manufacture and properties. Boer- L Boerhaave gives the following method for making wine haave'sme- vinegar: Prepare two large oaken hogsheads, with a wooden making^- grate» fastened at about one foot from their bottoms. Set the negar. hogsheads upright, and after having placed a moderately close layer of green twigs or cuttings of vine upon the grates, fill them up to the top with the foot stalks of grapes. The wine, to be converted into vinegar, is now poured into the hogsheads, so as to fill one of them to the top, and the other half full. They are left in this state for twenty-four hours; at the end of which time, the half full hogshead is filled to the brim, from the full hogshead. This operation is repeated every twenty-four hours, so as to keep the hogs- heads alternately full and half full, for fifteen days in sum- mer, but for a longer time in winter. This mode of proceed- ing has the effect of suspending the fermentation, in one of the hogsheads, every other day; as this process goes on in the half full hogshead only. If the fermentation was not in this way suspended, it would proceed too rapidly, and the spirituous part of the vinegar, be dissipated. Substances 2. Besides wine, the infusion of malt, cyder, molasses, which yield the refuse of raisins, and several other substances may be "negar. empi0yed to produce vinegar. The fermentation, by which liquids are converted into vinegar, is called the acetous. It is not easy to discover exactly what chemical operations are going on in the process. It appears certain, however, that the presence of mucilage is absolutely necessary, and that oxygen is absorbed from the air. Properties 3. Vinegar is a liquid of a reddish or yellowish colour, of vinegar, having an agreeable odour and pleasant sour taste. It is very liable to decomposition; but by being boiled for some time, this liability is removed. It is very little heavier than water. Properties IV. Acetic acid, obtained by the first process given in acid?6 ° l^e beginning of the present section, is in the form of a liquid, of an extremely pungent and acrid taste. It is very volatile, and, when heated in the open air, takes fire rea- dily. It acts with considerable energy upon animal sub- stances. When applied to the skin, it reddens and corrodes this membrane in a very short time. It combines with water in every proportion, and the union is attended by the evolution of a good deal of heat. Its specific gravity varies with the quantity of water which it may contain. It is 1 "08 or a maximum, when the acid contains somewhat more than half its weight of water, and it diminishes if the acid ACETIC ACID. 257 contain more or less than this quantity. When the acid is Chap. II. passed through a red-hot porcel tin tube, it is partially de- composed; and if the tube be filled with charcoal, it is com- pletely resolved into its constituents. Its combinations with salifiable bases are called acetates. These salts, when dis-Its salts tilled with certain precautions, yield a peculiar inflammable ^'then* liquid, which has been called pyro-acetic spirit. This liquid distilled. Will be noticed in the following paragraphs. 1. Pyro-acetic spirit may be obtained by distilling an Pvro-acetic acetate, at a heat always kept as low as possible. It is ex- f^™1^0™ actly the same, whatever acetate may be employed. Dif- ferent acetates, however, yield it in different quantities. Those acetates, whose bases are least easily deoxidized, yield the most. The acetates of soda and of potash yield a considerable portion of the spirit, and the acetate of barytes produces the spirit entirely, and no acetic acid. The pyro- acetic spirit was discovered by Chenevix. 2. Pyro-acetic spirit is in the form of a white limpid Its proper- liquid. Its taste is at first acrid and hot, but afterwards itUes" becomes cooling, and, in some sort, urinous. Its smell is peculiar, and may be compared with that which would be produced by a mixture of oil of peppermint and bitter al- monds. It is somewhat more than three fourths as heavy Spec. grav. as water. Its boiling point is at the temperature of 165°. °78, It is inflammable, and burns with a flame, white exteriorly, but of a fine blue colour within, leaving no residue. 3. Pyro-acetic spirit combines with water, alcohol, or the Action of volatile oils in any proportion. It dissolves a small portion (ll^erent - , , ' , £ , • ii i substances ot phosphorus or sulphur, and is an excellent solvent ot upon it. camphor. It dissolves potash also, and forms a dark co- loured liquid, from which the spirit may be separated by distillation unaltered. It is decomposed by sulphuric acid, which developes charcoal. It is altered in its properties by nitric acid, and its colour changed to yellow. It is rendered brown by hvdrochloric (muriatic) acid, and by distillation may be made to combine with this acid, forming a very different compound from hydrochloric ether. The exact composition of the pyro-acetic spirit is not known.—The consideration of the acetic acid will now be resumed. V. According to an analysis, performed by Berzelius, Composi- reduced to numbers, which best accord with the atomic Jjon °/ac«- theory, acetic acid is composed of Carbon 24*0—four atoms. Hvdrogen 3*2—three atoms, nearly. Oxygen 24*0—three atoms. Supposing this acid actually composed of the number of 2K 258 ACIDS. Book I. atoms, which appear to be indicated by the above analysis, Division II. tfren j^g number representing its atom would be 51. Its uses in VI. Acetic acid has several uses in medicine. In a dilute medicine. state, containing certain foreign substances, in the form of vinegar, it is used in scurvv, and for the purpose of coun- teracting the effects of narcotic poisons. In the form ot vinegar also, when mixed with water, it furnishes a very proper drink in inflammatory fevers, and its vapour may be inhaled with advantage in sore throat. Externally appli- ed, it forms a verv useful fomentation or bath. Several medicines are infused in vinegar, which infusions constitute what are called medicated vinegars. Of this class of remedies, there are the following officinal preparations; namely, aromatic vinegar or the vinegar of four thieves; it contains, infused, several aromatic vegetables, and formerly possessed considerable celebrity as a preventive of the plague. Also vinegar of colchicum or meadow-saffron, vinegar of squills, and camphorated vinegar. The three last mentioned medicated vinegars contain proof spirit also. Acetic acid, in its pure state, is a pretty powerful stimu- lant and rubefacient. In this state, it is employed in faint- ing, hysteria, headache and similar affections. The manner of using it, is to snuff it up the nostrils. SECTION IX. OF TARTARIC* ACID. I. Tartaric agid may be obtained by the following pro- cess: Dissolve bitartrate of potash (tartar) in boiling water, and add to the solution formed, carbonate of lime (chalk) in powder, as long as any effervescence should occur, or the solution redden vegetable blues. The lime of the car- bonate combines with the excess of acid in the bitartrate, so as to form tartrate of lime which is insoluble, while its carbonic acid is set free, and causes the effervescence above alluded to. After the chemical action is over, the resulting substances are tartrate of lime and neutral tartrate of potash. Separate the tartrate of lime by the filter, and pour upon it as much diluted sulphuric acid, as had at first been em- ployed of carbonate of lime, and let the mixture stand for twenty-four hours, stirring it occasionally. The sulphuric acid decomposes the tartrate, and combines with its base, Tartaric acid; how obtained. * From tartar the name of the substance, from which the acid is obtained TARTARIC ACID. 259 so as to form insoluble sulphate of lime, which falls to the Chap. II. bottom of the vessel, while the tartaric acid remains in solu- " tion. Decant the solution of tartaric acid, and evaporate it slowly. Crystals will be deposited whicn consist of tartaric acid in a state of hydrate. II. Tartaric acid exists ready formed, in combination Sources in with potash, in the lees of wine, and in the substance nature, and ....«•!• i il j-i c account ot which is found mcrusted upon the bottom and sides ot its disco- wine casks. This substance is called tartar. It had beenTerv- proved by Duhamel, Margraff and Rouelle, that tartar is composed of an acid united to potash; but the nature of the acid was altogether unknown. In 1770, Scheele succeeded in obtaining the acid of tartar in a separate state, and described many of its properties. It is this acid, under the name of tartaric acid, which furnishes the subject of the present section. III. Tartaric acid is in the form of crystals, white, firm, Properties and but imperfectly transparent. Its taste is exceedingly °£.tartar,c sour. It is not altered by exposure to air. It is somewhat s ' v more than one and a half times as heavy as water. When i-59. exposed to a heat, a few degrees above the boiling point, it melts into a limpid, transparent liquid, like water. At the temperature of 250°, it boils without losing its transparency. On cooling, it concretes into a hard semi-transparent mass, having considerable resemblance to sugar, which has been exposed to the same temperature. By this exposure to heat, the acid is altered in its properties, for it now deliquesces in the atmosphere. It dissolves in water. When the solution is very dilute, the acid suffers decomposition. It combines with the greater number of the salifiable bases in two pro- portions. Its salts are called tartrates. When these salts are distilled at a sufficiently strong heat, the acid is decompos- ed, so as to form water, carbonic acid, bihydroguret of car- bon (carburetted hydrogen), oil and charcoal. Hence, it is evident that its constituents are carbon, hydrogen and oxygen. IV. According to an analysis, performed by Berzelius, Composi- calculated in proportional numbers, which best agree with Jio? of l.ar_ the atomic theory, tartaric acid is composed of Carbon 24*1—four atoms, nearly. Hydrogen 2*6— Oxygen 40*0—five atoms. Supposing this acid to contain three atoms of hydrogen, and exactly four atoms of carbon, then the number repre- senting its atom would be 67. V. Tartaric acid, in its pure state, is not an article of the materia medica; but combined with certain salifiable bases, it forms some very important saline medicines, to be de- scribed hereafter. 260 ACIDS Book I. Division II. SECTION X. Benzoic acid; how obtained. Its proper- ties. Composi- tion. Medical usea. OF BENZOIC* ACID. (Formerly called, Flowers of Benzoin.—Salt of Benzoin.) I. Benzoic acid may be obtained by digesting benzoin in sulphuric acid. A crystallized substance is sublimed, which is benzoic acid. II. Benzoin is the product of a tree, which grows in the island of Sumatra, called by the botanists, styrax benzoe. It is not, however, the only substance which yields benzoic acid. Several other substances, both animal and vegetable, have been found to furnish it also. III. Benzoic acid is a fine light white powder, possessing a kind of ductility. Its taste is sweet, hot, and somewhat bitter. As usually prepared, it possesses a slight odour, which is peculiar and aromatic, and which it owes to the presence of a little aromatic oil; but, when perfectly pure, it has no smell. It suffers no alteration by exposure to air. It changes some vegetable blues to a red colour. It dis- solves in 200 parts of cold water, and in 20J parts of boil- ing water. It dissolves in sulphuric, sulphurous and nitric acids without alteration; and when water is added to the solutions, the benzoic acid separates and coagulates on the surface. It is not dissolved, however, by chlorine, hydro- chloric acid or phosphoric acid. Its combinations with salifiable bases are called benzoates. IV. According to an analysis by Berzelius, reduced to numbers, which best accord with the atomic theory, benzoic acid is composed of Carbon 29—five atoms, nearly. Hydrogen 2—two atoms. Oxygen 8—one atom. If this acid contained exactly five atoms of carbon, then the number representing its atom would be 40. V. At the present day, benzoic acid is seldom prescribed alone in medicine. It is, however, an ingredient in the pa- regoric elixirs of the British colleges. There is no reason to believe that the acid, by its presence in these prepara- tions, adds much to their efficacy; but, having an agreeable taste and smell, it renders them less unpleasant for exhibi- tion. * Derived from benzoin, a kind of resin brought from the East Indies, from which substance the acid was first obtained. SACLACTIC ACID. 261 Chap.IL SECTION XL OF SACLACTIC" ACID. Acid of the Sugar of Milk of Scheele. I. Saclactic acid may be obtained by the following Saclactic process: Pour two parts of nitric acid upon one part ofa£1(H h*\w gum arabic, or other similar gum, contained in a retort, and expose the mixture to a gentle heat, until some deu- toxide of azote (nitrous gas) and carbonic acid come over. The mixture, upon cooling, deposites a powder, which may be separated by the filter. This powder is saclactic acid, rendered impure by admixture of a portion of oxalate of lime, and a compound of gum and lime. The oxalate of lime may be separated by digesting the powder in diluted nitric acid; and the compound of gum and lime, by treating it with hot water, which takes up the acid alone. The hot solution thus obtained, upon cooling, deposites saclactic acid in the form of crystals. II. Saclactic acid may be prepared from sugar of milk.f When this substance is employed for its preparation, it is obtained pure, at once, by the action of nitric acid. Saclac- tic acid was discovered, in 1780, by Scheele. III. Saclactic acid is a white, gritty powder, possessingitsproper a slightly sour taste. It is soluble in 60 parts of boilingties- water. The hot solution, as it cools, lets fall the acid in the form of crystals. When in solution, it reddens the infusion of turnsol. When exposed to heat, it suffers decomposition. When distilled, the products are an acid liquor, a red-co- loured acrid oil, carbonic acid gas, bihydroguret of carbon, and a large proportion of charcoal. Its combinations with salifiable bases are called saclactates. IV. According to an analysis by Berzelius, calculated inComposi- numbers, which best agree with the atomic theory, thistion- acid is composed of Carbon 34*8—six atoms, most nearly. Hydrogen 5*3—five atoms, nearly. Oxygen 64*0—eight atoms. Supposing this acid to contain exactly six atoms of carbon and five atoms of hydrogen, then the number representing its atom would be 105. • Abbreviated of the two Latin words, saccharum, sugar, and lac, milk; be- cause the acid was first obtained from the substance called sugar of milk. f Supir of milk is a peculiar white crystallized substance, obtained from the whey ot milk, to be described hereafter. 262 ACHKv Boor I. Division II. ----- SECTION XII. OF CITRIC* ACID. ( rystallized Citric Acid of the Dublin College. Citric acid; I. Citric acid may be obtained by saturating boiling how obtain-lemonjuice with carbo"nate 0f ijme (chalk) in powder: the carbonate becomes decomposed, its acid flies off in the state of gas, while its base combines with the pure acid of the lemonjuice, so as to form the compound called citrate of lime. Separate the citrate of lime by the filter, and, after having washed it well, add to it sulphuric acid diluted with six times its weight of water, in sufficient amount to separate all the lime. Boil the mixture, thus formed, tor a few minutes, and then separate the insoluble powder, which will be formed, and which consists of sulphate of lime. The remaining liquid is now a solution of citric acid. By eva- porating it to the consistence of a syrup, and setting it aside to cool, the acid will be deposited in the form of crystals. II. Citric acid exists most abundantly in the juice of oranges and lemons; but it is present in the juices of many other vegetable substances. It was first obtained in a pure state, and described accurately, by Scheele. its proper- III. Citric acid, in the form of crystals, has an intensely t,es- sour taste, which becomes pleasant, when it is sufficiently diluted with water. It is not altered by exposure to air. It is exceedingly soluble in water. It dissolves in three-fourths of its weight of cold water, and in half its weight of this liquid at the boiling temperature. The solution may be kept for a long time, in close vessels; but at last it putrefies and the acid is decomposed. When the acid is subjected to the action of concentrated sulphuric acid, it is converted into acetic acid. By nitric acid, it is changed into oxalic acid; but, to produce this change, care must be taken not to use too large a quantity of nitric acid, otherwise acetic acid would be formed. When exposed to the open fire, it first melts, then swells and exhales an acrid vapour, and a quantity of charcoal is left behind. When distilled, in close vessels, it evaporates, partly unaltered, and partly decom- posed into acetic and carbonic acids and bihydroguret of carbon (carburetted hydrogen), and a portion of charcoal is left behind. Its combinations with salifiable bases are called citrates. • From citrus, the Latin name for the orange tree. CITRIC ACID. 263 IV. According to an analysis by Berzelius, calculated Chap II. in numbers, which best accord with the atomic theory, compo^i- citric acid is composed of ll('"- Carbon 42*2—seven atoms, nearly. Hydrogen 3*9—four atoms, nearly. Oxvgen 56*0—seven atoms. Upon the supposition that this acid contains exactly the number of atoms, which appear to be indicated by the above analysis, then the weight of its atom would be 102. V. Citric acid forms the important part of the acid Medical drinks, made from the juice of lemons and limes, which uses" are so usefully employed in inflammatory fevers. In the form of crystals, as directed to be prepared by the Dublin College, it is not liable to spoil, as when in the form of lemon juice; hence it is the best preparation of the acid for medical employment. Of the acids, composed of carbon, hydrogen and oxy- gen, belonging to the present class, the ten already described are the only ones, which have been analyzed with tolerable accuracy. The atomic composition of these acids is reca- pitulated in the following table. NAMES. ATOMS OF Carbon. Hydro-gen. Oxygen. Gallic acid. Formic acid. Oxalic acid. Sorbic acid. Succinic acid. Acetic acid. Tartaric acid. Benzoic acid. Saclactic acid. Citric acid. 2 2 2 2 4 4 4 5 6 7 1 1 1 7 2 3 3 2 5 4 1 3 4 3 3 3 5 1 8 7 Table of the atomic composi- tion of the ten acids last des- cribed. By multiplying the atoms of carbon by 6, and those of oxygen by 8, the products will be the proportional quanti- ties of these two constituents, in the acids above enumera- ted. The atom of hydrogen being taken at unity, the pro- portional quantity of this constituent is indicated by the number of atoms themselves. The atomic composition of some of these acids, as given Variations by Dr. Thomson,* has not been followed in this work.from * Sorbic acid has been placed among the acids of this class, whose composition is known, since the above was written. Its atomic composition is deduced from a recent analysis by Vauquelin. 264 ACIDS. Book I. Division II Thomson's statements of the ato- mic com- position of some of these acids, noticed, and the ginunds of them ex- plained. Explana- tion of the manner in which the atoms of ternary compounds may com- bine. The atomic composition of the oxalic acid is deduced from an anahsis given by Gay-Lussac, rather than from one made by Berzelius, which cannot be employed without creating the anomaly of a fractional atom of hydrogen, or deducing a disproportional atomic amount for the other constituents ot this acid. The atomic composition of citric acid is given differently from Dr. Thomson; because the hydrogen of the acid is given by this chemist theoretically, and not in accordance with actual analvsis. Dr. Thomson gives the gallic acid, as composed of six atoms of carbon, three atoms of hydrogen, and three atoms of oxygen; which composition, if I understand the atomic theory right, in nowise differs from two atoms of carbon, one atom of hy- drogen and one atom of oxygen, or Dr. Thomson's num- bers, reduced to their lowest terms. For a similar reason, benzoic acid is given as a compound of five atoms of car- bon, two atoms of hydrogen, and one atom of oxygen, instead of Dr. Thomson's numbers of fifteen atoms ot car- bon, six atoms of hydrogen and three atoms of oxygen. By possibility, indeed, two ternary compounds of the same ultimate constituents, united in the same proportions, may not be identical, in consequence of some variation, between them, in the predisposing binary combinations of their constituents: and, taking this view of the subject, Dr. Thomson's atomic compositions for citric and benzoic acids may differ from those here adopted. But, however this question may be decided in the abstract, it is believed that no instance can be adduced of two substances, agree- ing in the way here mentioned, which are not identical. The atomic compositions of the ten acids, last described, have not been given, under the influence of a belief that much dependence can be placed upon their accuracy; but as approximations only, which may be received, until cor- rected by more exact observations. Three atoms of different bodies cannot be conceived to unite together as atoms. Two of them must first combine together, and the new atom, thus formed, may then com- bine with the third. Neither can an unequal number of atoms of three different substances unite together, without the supposition being necessary of a previous binary com- bination. The atoms of two of the substances, after having combined together, may then unite with the atoms of the third: or the atoms of any two of the substances may separately combine with atomic portions of the third, and the two binary compounds, thereby formed, may afterwards unite; but in no other way, in the case here supposed, is it probable that a union can take place by atoms. Taking this MELLITIC ACID. 265 view of the subject, therefore, it is very probable that all Chap. II. the acids of this class, except the two first, are compounds, in different proportions, of carbonic oxide or carbonic acid, with the two hydrogurets of carbon, modified by the pre- sence of different portions of water. The description of the remaining acids, embraced by the fifth class, will now be resumed. SECTION XIII. OF MELLITIC* ACID. I. Mellitic acid may be obtained by boiling the mineral Mellitic called mellite, which is composed of this acid and alumina, "f"1! how r , • " ■ . • t 'obtained. in a state ot powder, in seventy-two times its weight ot boiling water. The mellitic acid dissolves in the water and the alumina separates in flakes. Remove the alumina by the filter, and evaporate the clear solution, until it form crystals. These crystals will consist of mellitic acid. II. Mellitic acid has heretofore been found only in the Exists only mineral called mellite. This mineral has usually a honey-m mel,lle* yellow colour, but sometimes a straw-colour. It is crystal- lized, generally smooth and brilliant, and presents, when broken, the glassy fracture. It has some resemblance to amber. It is partly combustible. It is an exceedingly rare mineral, having been heretofore found only in Thuringia and Switzerland. It was first analyzed, and a peculiar acid found to be one of its constituents, by Klaproth in 1799. III. Mellitic acid, in the form of crystals, has a brownish its proper- colour, and a taste, at first sweetish-sour, but afterwards ties' bitterish. It is very soluble in water. When exposed to heat, it emits abundance of smoke, without smell, and the residue is a small quantity of insipid ashes. It combines with some of the salifiable bases, and forms salts called mellates. Its exact composition has not been made out; but there is no doubt that it is a compound of carbon, hydrogen and oxy- gen. * This acid has its name from the mineral called mellite. The name of this mineral is derived from mel, Latin for honey, on account ef its honev-yellow co- lour. 2 L 266 ACIDS Book I. Division II. SECTION XIV. Camphoric acid; how- obtained. Its proper- tics. OF CAMPHORIC ACID. I. Camphoric acid may be obtained by distilling to- gether, one part of camphor, and eight parts of nitric acid, at a sand heat: a good deal of deutoxide of azote (nitrous gas) and carbonic acid are extricated. As soon as all the nitric acid has come over, the same quantity, as first em- ployed, is to be distilled off the camphor, at two successive distillations. After the retort has become cool, a number of crystals will make their appearance. These crystals consist of camphoric acid. This acid was discovered by Kosegarten, in 1785. II. Camphoric acid, in the form of crystals, has a snow- white colour, a slightly sour, bitter taste, and a smell re- sembling that of saffron. It reddens vegetable blues. When exposed to the air, it effloresces. It dissolves in ninety-six parts of water, at the temperature of 60°, and in eleven partB of boiling water. It is soluble in hydrochloric, sulphuric and nitric acids. When distilled, it first melts, and then sublimes unaltered. When placed on ignited coals, it emits dense aromatic fumes, and is entirely dissipated. It combines with some of the salifiable bases, and forms salts called campho- rates. Its constituents are carbon, hydrogen and oxygen. SECTION XV. ed OF MALIC* ACID. Malic acid; !• Malic acid may be obtained by the following pro- how obtain-cess: Saturate the juice of apples with carbonate1 of potash, and, to the liquid obtained, add acetate of lead (sugar of lead) as long as any precipitate should appear: the precipi- tate formed will be a compound of malic acid and protoxide of lead. Separate it by the filter, and, after having washed it carefully, pour upon it, diluted sulphuric acid, until the solution formed has a perceptibly sour taste: the added acid will combine with the protoxide of lead, and precipitate in the form of sulphate of lead. After this sulphate is removed by the filter, the remaining liquid will be a solution of malic acid. * From malum, the Latin word for apple; because the malic acid was first ob- tained from the juice of this fruit. LACTIC ACID. 267 II. Malic acid may be obtained from other substances, Chap, il besides the juice of apples. It exists in abundance in the Substances juice of the house-leek (sempervivum tectorum); in which whUsh fur- plant, it is combined with lime. It may be procured from Dli sugar, by distillation with its own weight of nitric acid. It was discovered in 1785 by Scheele. III. Liquid malic acid has a reddish-brown colour, and Its proper- a very sour taste. When evaporated, it does not crystallize,tie8" but becomes thick and viscid, resembling a syrup. When exposed to a dry atmosphere, in thin layers, it dries entire- ly, and assumes the appearance of varnish. It is very soluble in water. When acted upon by sulphuric acid, it is charred, but by nitric acid, it is converted into oxalic acid. When subjected to distillation, the products are an acid water, a little bihydroguret of carbon, and a large quantity of carbonic acid. When heated in the open fire, it turns black, and emits acrid fumes, and a voluminous charcoal is left behind. Hence it is evident that this acid is a compound of carbon, hydrogen and oxygen. Its combinations with salifiable bases are called malates. SECTION XVI. OF LACTIC* ACID. I. Lactic acid may be obtained by the following pro-Lactic acid; cess: Evaporate sour whey to one-eighth, and separate the h°wobtam_ cheesy part by the filter. Precipitate the phosphate of lime, present in the remaining liquid, by means of lime water. Separate any lime, which may have been dissolved, by means of oxalic acid. Evaporate the liquid, as it now stands, to the consistency of honey, and treat it with alcohol: This liquid dissolves the lactic acid alone, and leaves every thing else untouched. To the alcoholic solution of the acid, add a small quantity of water, and distil with a moderate heat: the alcohol is driven over, so that nothing remains in the retort but a solution of lactic acid in water. II. Lactic acid was discovered, in 1780, by Scheele. Its existence was afterwards doubted, and several chemists supposed that they had proved it to be acetic acid, con- taminated with some foreign matters. In 1808, Berzelius subjected the acid to a thorough investigation, which termi- nated in completely establishing its peculiar nature. • From lac, the Latin word signifying milk; it being this liquid from which lactic acid is procured. 268 ACIDS. Book I. III. Lactic acid is in the form of a liquid, having a mMon11- brownish-yellow colour, and a sharp sour taste. It h s no Its proper- smell when cold, but when heated, it emits a sharp sour odour, not unlike that of sublimed oxalic acid. It is not ca- pable of crystallizing. When evaporated to dryness, it as- sumes the appearance of a smooth varnish. When distilled, it is converted into empyreumatic oil, water, acetic acid, carbonic acid and inflammable gas. When heated in the open fire, it boils, emits a sour smell, and leaves a bulky charcoal. It combines with some of the salifiable bases and forms salts called lactates. Its constituents are carbon, hydrogen and oxygen; but the proportion, in which these bodies are combined is not known. SECTION XVII. OF PYROTARTARIC* ACID rVrotaiia- I. Pyrotartaric acid may be obtained by the follow- nc acid; jng proCcss: Distil a quantity of bitartrate of potash (tartar), ed. and, after saturating the acid liquor which will be obtained with potash, let it stand to crystallize. The crystals, which form, consist of the acid under description, combined with potash; they may be purified by repeated solution and crys- tallization. By distilling these crystals with diluted sulphuric acid, they are decomposed, sulphate of potash becomes formed, and the pyrotartaric acid passes over into the receiver, where it condenses into a liquid; when this liquid is exposed to spontaneous evaporation, the acid is deposited in the form of crystals. its history. II. Pyrotartaric acid, in an impure state, was known before tartaric acid. Tartar had been long considered an acidulous salt, whose base was easily shown to be potash by combustion. When distilled, it yielded an acid liquor; but this was evidently not the acid of tartar, since it did not form tartar by combining with potash. This inference was subsequently fully confirmed, in 1770, by Scheele, who discovered the true acid of tartar. The acid liquor thus obtained from tartar, although different from tartaric acid, yet appearing to possess peculiar properties, the French chemists, when they adopted their new nomen- clature, gave it the name of pyrotartaric acid. Its peculiar * From xvg, fire, and tartar, the name of the salt from which this acid is ibtained by the action of fire. MOROXYLIC ACID. 269 nature was afterwards, in 1799, called in question by Cbap.ii. Fourcroy and Vauquelin, who supposed they had proved it to be acetic acid, disguised by admixture of empy- reumatic oil. This conclusion of the French chemists was combated, in 1806, by Gehlin, who revived the original opinion of its peculiar nature. In consequence of the expe- riments of this chemist, Fourcroy and Vauquelin submitted the acid liquor to a new examination, which terminated in confirming the conclusions of Gehlin. III. Pyrotartaric acid is in the form of crystals, and Its proper- possesses an extremely sour taste. It is readily soluble in Ues- water, and the solution formed deposites crystals by spon- taneous evaporation. When heated, it melts, and sublimes in the form of a thick smoke, without leaving any residue. It combines with some of the salifiable bases, forming salts called pyrotartrates. Its ultimate constituents are carbon, hydrogen and oxygen; but the proportion in which they are united is not known. SECTION XVIII. OF MOROXYUC* ACID. I. Moroxylic acid may be obtained by the following Moimylie process: Dissolve the saline exudation, found on the bark ac,di h°w of the white mulberry tree, in water, and let the solution stand, until it deposite crystals. These crystals will be small and needle-form, and consist of a salt composed of the acid under description and lime. After a sufficient number of them have been deposited, dissolve them in water, and add to the solution formed, acetate of lead (su- gar of lead). This addition decomposes the moroxylate of lime, and causes a moroxylate of lead to precipitate. Sepa- rate the moroxylate of lead, and decompose it by means of sulphuric acid, diluted with twice its weight of water. The lead falls in combination with this acid, in the form of an insoluble sulphate of lead; while the moroxylic acid remains in solution. Separate the sulphate of lead, and evaporate the clear solution, until crystals make their appearance. The crystals, which will form, consist of moroxylic acid. This acid was discovered, in 1803, by Klaproth. II. Moroxylic acid is in the form of fine needle-shaped Its propet- _____^_^__________—________^____ t'cs- * From moras, the mulberry tree, and |wa«v, wood. 270 ACIDS Book I. crystals, of a pale wood colour. Its taste is similar to that ■ "'5'0." If' of succinic acid. It is soluble in water. It suffers no altera- tion by exposure to the air. When distilled, an acid liquor is first driven over, and afterwards part of the acid sublimes unaltered upon the upper part and the neck of the retort. What remains behind is a coaly residuum. Its combinations with salifiable bases are called moroxylates. Its ultimate constituents are carbon, hydrogen and oxygen. SECTION XIX. OF SUBERIC* ACID Suberic I. Suberic acid may be obtained by the following pro- obta',,T cess: ^gest one Part °*: cork *n s'x Parts °*7 nitric acid. After the action of the acid is over, evaporate the mixture to the consistence of an extract, dilute it with water, and then expose it, for some time, to a sand heat. The liquid, thus obtained, by being set aside, forms on its surface a substance resembling wax, and deposites white flocks at its bottom. Both these substances must be separated, and the remaining liquid, concentrated by evaporation. As the concentration proceeds, a powder falls, which, after being washed with cold water, is pure suberic acid. This acid was discovered, in 1787, by Brugnatelli. its proper- II. Suberic acid is in the form of a white powder, having some resemblance to starch. Its taste is sour, without any mixture of bitterness. It dissolves in 80 parts of water, at the temperature of 55*5°, and in 38 parts, at the tempera- ture of 140°. When exposed to heat, it first melts, and then sublimes. Its combinations with salifiable bases are called suberates. Its ultimate constituents are carbon, hydrogen and oxygen. ties. SECTION XX. OF LACCIC ACID. Laccic I. Very little is known respecting laccic acid. It was uined from obtained, by John, from stick-lac, a substance which comes lar. from the East Indies. This substance has been ascertained * From suber, the Latin name for cork. KINIC ACID. 271 to constitute the nidus of a certain insect, called chremes Chap, ii lacca. When chemically examined, it is found to consist principally of resin. II. Laccic acid has a wine-yellow colour, and a sour Its proper- taste. It is soluble and crystallizable. Its combinations with Ues- salifiable bases are called laccates. Its ultimate constituents are carbon, hydrogen, and oxygen. SECTION XXI. OF KINIC* ACID. I. Kinic acid may be obtained by the following pro-Kinic acid; cess: Macerate yellow Peruvian bark in cold water, and ^w obtaiir- concentrate the infusion formed by evaporation. Let it stand for some time, until crystals make their appearance. Separate the crystals which form, and purify them by re- peated crystallizations: they consist of the acid under description, combined with lime. In order to obtain the kinic acid in a separate state, dissolve the crystals in water, and add oxalic acid to the solution formed. This acid sepa- rates the lime, in the form of an insoluble oxalate of lime, while the kinic acid remains in solution. Kinic acid was discovered by Vauquelin, combined with lime, in a salt, prepared from Peruvian bark, by Deschamps, junior, an apothecary of Lyons. Deschamps' salt was, therefore, a kinate of lime. II. Kinic acid, in the form of solution, has a brown Its proper colour, and a sour and somewhat bitter taste. It is nottie*' altered by exposure to air. When concentrated, by evapo- ration, to the consistency of a syrup, it does not crystallize spontaneously, but instantly, upon being touched with a glass rod. When exposed to the action of heat, on burning coals, it first melts, then froths and blackens, and after- wards exhales an acrid vapour. The residuum is a small portion of charcoal. Its ultimate constituents are carbon, hydrogen, and oxygen. * Contracted of quinquina, the French name for the Peruvian bark 272 ACIDS Book I. Division II. Znmic aciil; how obtained. Its proper. ties. SECTION XXII. OF ZUMIC* ACID. I. Zumic Acid may be obtained by the following pro- cess: Allow a mixture of rice and water to ferment; and evaporate the liquid thus procured, after being strained, almost to dryness, so as to form a gummy mass. Digest the gummy mass in alcohol, and evaporate the solution formed, until crystals make their appearance. These crys- tals consist of zumic acid combined with a portion of lime. Separate them and dissolve them in water, and, to the solution formed, add barytes water as long as any preci- pitate ensues: the barytes combines with the zumic acid, and remains in solution, while the lime is precipitated. Separate the lime by the filter, and add to the clear solution sulphuric acid, in just sufficient quantity to precipitate all the barytes of the zumate of barytes. The precipitate thus formed being separated, nothing remains but a solution of zumic acid. II. Zumic acid was lately discovered by Braconnot, by treating rice in the manner just detailed. It is not, how- ever, peculiar to the fermentation of rice, but appears to be formed pretty generally by the spontaneous fermentation of vegetable substances. III. Zumic acid is a colourless liquid, possessing a very sour taste. It is incapable of crystallization; but, upon suf- ficient evaporation, it forms a syrup. When subjected to distillation, it yields charcoal and acetic acid. Hence its constituents must be carbon, hydrogen and oxvgen. Its combinations with salifiable bases are called zumates by Dr. Thomson.f Boletic acid. SECTION XXIII. OF BOLETIC* ACID. I. Boletic acid was discovered, in 1811, by Bracon- not, in the expressed juice of the boletus pseudo-igniarius. • Zumic is the name given to this acid by Dr. Thomson, instead of nanceic, derived from Nancy, the name of the city in which its discoverer resides. Dr. Thomson's name is derived from £vju.* leaven. 11 find, by a notice contained in the Annals of Philosophy, Vol XII. p. 391, that the peculiar nature cf zumic acid has been called in question by Yogel. This chemist informs us that he has obtained it from different species of corn, and finds it, when properly purified, to be the lactic acid of Berzelius. t From boletus, the L:itin name for the mushroom. BOLETIC ACID. 27* It is a crystallized solid, of a white colour. Its taste is si- Chap. II. milar to that of bitartr >te of potash (tartar). When in the state of solution, it reddens vegetable blues. It is not alter- ed by exposure to air. It dissolves in 180 parts of water at the temperature of 68°. When distilled, the greatest part of it sublimes unaltered. When exposed to the action of the open fire, it rises in white vapours, which irritate the throat, and condense on surrounding bodies, in the form of a larinaceous powder. Its combinations with salifiable bases ar<- called boletates. Its ultimate constituents are probably carbon, hydrogen, and oxygen. Having thus finished the consideration of the acids, in conformity with the plan pursued with regard to the other sets of chemicnl bodies, their principal properties will be recapitulated in a series of tables. 2 M I. Table of Acids, whose Base* form Acid Compounds by combining ivith Oxygen or Hydrogen indifferently. Nsur.t s :'r;u ,lv. Kft'e.'tSOf 1 Wei-lit of all atom of each. :uid time of discovery. to :.i,r;^i'e-gMli.ii.. Compared, ^i™"* with air. | *" ' water. heat or 1 Composition. colli 1. Chloric Acid. Hyperoxymu-riatic ucid. Gay-Lussac, in a separate state; 1814. Liquid. Colourless. None, un-less when concentra-ted. Very acid. Chlorine 36 one atom. Oxygon 40 fi\e atoms. 76 2. Oxychloric Acid. Perchloric acid of'Dr.Thomsou. Count Von Stadion. Liquid. ----- Chlorine 36 one atom. Osy(»en 56 seven atoms. 92 (Hydro-■ chloric lAcid. Composition ascertained by Gay-Lussac and Thenard. Gaseous. Invisible. Peculiar. Very sour. Forms, with wa-ter, liquid hy-drochloric acid. 1-2847. L'li Inline 36 one atom. Hydrogen 1 one atom. 37 1 il.iqilid Hy-rihochloric [Acid. Muriatic acid. Marine acid. Spirit of Sea Salt. Liquid. Colourless when per-icvtly pure. The same as that of the gase-ous acid. Combines with moisture, and appears in white fumes. 1-203. When a satura-ted solution, water 1 vol. ai-idgas 51* vol. 4. Iodic Acid. 11. Davy. White and Solid. semi-trans-.parent. None. Astringent and sour. Readily solu-ble. Deliquescent in a moist air. Inline 125 one atom. Oxygen 40 live atoms. 105 5. Hydriodic Acid. Clements. Gaseous. 1 Invisible. Like that of hydro-chloric acid. Very sour. Keadily absor-bable by water. 4-443. Iodine 125 uiie atom. Hydrogen 1 one atom. 120 k Sulphuric lAcid. Absolute sul-phuric acid. Solid, | In the below the solid form, temp, of ilikc asbes-66". tos. X- ■ I Dissolves m wa-ter, with which it forms liquid sulphuric acid. Fumes and flies oft' in \apour. Sulphur 10 one atom. Oxygen 24 three atoms. 40 il.iqilid ■ Sulphuric I (Acid. || Vitriolic acid. Oil ol Vitriol. Liquid of | an oily con- Colourless. sistency. Nearlj none. Intensely sour. Attracts mois-ture and be-comes heavier. Maxiinuiu. 1-85. Boils at 'c . . .. 620=. nau. Sulphuric acid combined with Futto Ht various quanti-— 36", max. ties of water. of Acids, whose Bases form Acid Compounds by combining with O.vygen or Hydrogen indifferently__Concluded. 1 Names adopteil in tlits work. OKI names or Synonymes. Discoverers, and time of discovery. State as to aggre-gation. Colour. Smell. Taste. Solubility. Effects of ex-posure to ail- Specific Compared with air. (iravity. Compared with water. K fleets of heat or eolil. Composition. Weight of an atom of each. 7. Sulphurous Acid. Scheele and Priestley; 1774. Gaseous. Invisible. Sirongand Very acid suffocat- and sul-ing. phurous. Water takes up 33 times its vo-lume of the gas.i 2-22. Condenses into a liq. bv a cold of- 18°. Sulphur 16 one atom. Oxygen 16 two atoms. S3 ■i. Hypnsul-phurutis Acid. Not yet ob-tained in a sr para te-state. Supposed to be Sulphur 16 one atom. Oxygen 8 one atom. 24 0. Hydrosul-phuric Acid. Sulphuretted Hydrogen. Hydrothionic acid of the Germans. Scheele; 1777. Gaseous. Invisible. Strong and fetid. Water takes up 2-5 times its vo-lume of the gas. 1-19. Sulphur is one atom. Hydrogen 1 one atom. 17 to. Hydrosul-phurous Acid. Hydroguretted Sulphur. Supersulphuret-ted Hydrogen. Scheele. Liquid resembling oil. Yellowisli-brown. Decomposed in-to hydrosulphu-ric aciil gas and sulphur. Sulphur. Hydrogen. 11. Selenic Acid. Berzelius. Solid. Acid and burning. Readily soluble. Absorbs mois-ture. Selenium 40 one atom. Oxygen 16 two atoms. -56 12. Hydrosele-nic Acid. Berzelius. Gaseous. Invisible. Acts with violence on the sense of smell. Dissolves in wa-ter, totally de-prived of a;r. Selenium 37 Hydrogen 1 one atom. 13. Telluric Acid. Oxide of Tellurium. Powder. White. Melts into a stiaw-eo-lourtd mass. Tellurium 32 one atom. Oxygen 8 one atom. 40 14. I'ulrol.-I-lurio Aeid.i '......._J Tellureltrd H\ilr.,gen. H. Daw; 1809.' Gaseous. Invisible- Strong and peculiar. Forms a claret-coloured solu-tion. II. Table of Acids, whose Bases form Acid Compounds by combining with Oxygen only. Names. Old names or Synonymes. Discoverers, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. Specific Gravity. Effects of heal or cold. Composition. Weight of an atom of each. 1. Nitric Acid. Spirit of Nitre. Aqua Fortis. Raymond Lully; I.'itli century. Composition discovered by Cavendish. Liquid. Transpa-rent and colourless. Its fumes, acrid and disagree-able. Exceed-ingly acrid. It ha* never been obtained free from water. Attracts mois-ture. Maximum, 1-55. Maximum boiling point, 248°. Freezing point, —66". Azote 14 one atom. Oxygen 40 five atoms. 54 X Nitrous 1 Acid. Scheele. Very volatile 1 Orange-liquid. 1 coloured. Very sour. Decomposed by water. Emits fumes. 1-451. Boiling point, 82". Azote 14 one atom. Oxygen 38 four atoms. 46 3. Hyponi-trous Acid. '- Pernitrous Acid of Gay-Lussac. Existence made probable by Gay-Lussac. Not known; it never hav-ing been ob-tained in a se-parate state. Supposed to be Azote 14 one atom. Oxygen 24 three atoms. 38 4. Carbonic Acid. Fixed Air. Aerial Acid. Meplntic Acid. Calcareous Acid. Black; 1755. Composition discovered by Lavoisier. Gaseous. Invisible. None. Water, at 55°, absorbs a little more than its bulk. 1-527. Carbon 6 one atom. Oxygen 16 two atoms. 22 .'. Boracic Acid. Sedative or Narcotic Salt of Homberg. Homberg; 1702, Composition discovered by Gay-Lussac & The-nard and H. Davy. Solid, in the form of scales. Silver^ white. None. Sour at first, be-coming bitt. rish and cooling. Sparingly-soluble. 1-479. After fusion, 1-603. Melting point, at a nil heat. Roron. Oxjgen. '". Ph.i-phuric Acid. Coml>osition discovered by Lavoisier. Solid. Semi-transpa-rent. None. Very sour. Dissolves readily. Deliquesces into an oil-likt liquid. 3-687. Melt, at a red heat After fusion, ealli it phos-phoric glass. Phosphorus li one atom. Oxvgen 16 two atoms. 28 7. Phospho-rous Acid. First obtained pure by H. Davy. Solid. Very sour. When healed, catclies tire Phosphorus 12 out atom. Oxjgen S one atom. 90 Table of Acids, whose Bases form Acid Compowids by combining with Oxygen only—Continued. ji Old namc3 Names, h or 1 Synonymes. Discoverer, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. •Specific Gravity Effects of heat. Composition. Weight of an atom of each. 8. Hvpophos-phoroua Acid. Dulong; 1816. Liquid; viscid when concentrated. Very sour.j^l^ater. Ai'>°'''" •W-1 1 Phosphorus 24 _ . I two atoms. Decomposed. 0xyffen 8 one atom. 32 9. Arsenic Acid. Solid. White. Scarcely any, when dry. In so-lution, acrid and metallie. Dissolves in 6 parts of colli water, and in 2 parts of hot. Attracts moisture. 3-39. Melts into a glass, and emits oxygen. Arsenic 46 Oxygen 24 three atoms. 10. Arsenious Acid. Oxide of Arsenic. Arsenic. White Arsenic. Compact solid. White. When heated like that of garic Sharp and acrid, with some sweetness. Dissolves in 80 parts of cold water, and in 15 parts of hot. 3 70. Sublimes at the temp, of 283°. Melts in close vessels. Arsenic 47 one atom. Oxygen 16 two atoms. 63 11. Chromic Acid. Vauquelin; 1797. Solid. Deep-red. Acrid, sharp and metallic. Soluble. Absorbs moisture slowly. Gives out oxygen gas. Chromium 28 one atom. Oxygen 24 three atoms. 52 12. Molybdic Acid. Scheele; 1778. Powder. White. Dissolves in 960 parts of boiling water. In the open air, sublimes; in close ves-sels, melts. Molybdenum 48 one atom. Oxygen 24 three atoms. 72 13. Molybdous Acid. Powder. Blue. Soluble. Molybdenum 48 one atom. Oxygen 16 two atoms. 64 14. Tungstic Acid. Scheele; 1781. Powder. Yellow. Insoluble. Tungsten 96 one atom. Oxygen 24 three atoms. 120 Table of Acids, whose Bases form Acid Compounds by combining with Oxygen only—Concluded. Names. Old names or Synonymes. Discoverer, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. Specific Gravity. Effects of heat. Composition. Weight ! of an atom of each. 15. Colnmbic Acid. Hatchett; 1801. Powder. White. Insoluble. Columbium 146 one atom. Oxygen 8 one atom. 154 16. Antimonic Acid. Powder. Straw-coloured. Insoluble. At a red heat, gives out oxy-gen gas. Antimony. Oxygen. 17. Antimoni-ous Acid Argentine Flowers of Antimony. Fine white. Insoluble. Fuses at a pretty high heat. Antimony. Oxjgen. to "J 00 III. Table of Acids, whose Bases form Acid Compounds by combining with Hydrogen only. Names adopted in this work. Usual chemical names. Discoverers, and time of discovery. St:»te as to aggregation. Colour. Smell. Taste. Solubility. Effects of ex-posure to air. Specific Gravity. Effects of heat or cold. Composition. Weig',1 of an atom ot each. 1. Hydrofluo-ric Acid. Fluoric acid. First obtained pure by Gay-Lussac and Thenard; 1808. Constituents made probable by Am-pere and H. Davy. Liquid. Colourless. Like that ofhydroch-ioric acid, hut stronger. Not known; very corro-sive. Combines with water violently, evolving heat. Fumes violent-ly, and is dissi-pated. 1-06. 1 Boiling point,! Constituents very low. supposed to be Freezing a peculiar radi-point, lower cal and hydro-than-4°. gen. 2. Hydrocya-nic Acid. > Prussic acid. True nature disco-vered by Gay-Lussac; 1815. Liquid. Colourless. Strong; like that of peach blos-soms. Sharp; at first cool-ing, but af-terwards burning. Combines with water. At the temp, of 64-5 o, 0-69. As vapour, 0-94. Boiling point. Cyanogen 26 79*7°. one atom. Freezing Hydrogen 1 point, 5°. I one atom. 27 IV. Table of Acids of Irregular Constitution. Names adopted in this work. Usual chemical names, or Synonymes. Discoverers, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubilitv. Effects of ex-posure to air. Specific Graiit.i . Composition. Weiglit of an atom of each. 1. Chlorocar-bonic Acid. Phosgene gas of J. Davy. J. Daw; 1812.' Gaseous. Invisible. Like the mixed odours of chlorine and ammonia. Decomposed by water into hydro-chloric and car-bonic acids. Emits very strong and suf locating fumes. Carbonic oxide 14 | one atom. IChl irine 36 uuc atom. 50 2. Chloriodic Acid. Chloruret of Iodine of Gay-Lussac. H. Davy, and Gay-Lussac. Volatile Solid. Yellow. Forms a colourless solution. Deliquesces. Chlorine. Iodine. 3. Borofluoric Acid. Fluoboric acid of Gay-Lussac. Gay-Lussac and Thenard; 1808. Gaseous. Invisible. Like that of hydrochloric acid. Exceed-ingly acid. Water absorbs 700 times its bulk, and becomes 4 iths heavier. 2-57. Boron. Fluorine. 4. Silicofluoric Acid. Siiicated Fluoric Acid. Fluosilicic Acid. Fluoric Acid of Scheele. Discovered by Scheele. True nature made out by J. Davy. Gaseous. Invisible. Like that of hydrochloric acid. Very sour. Water absorbs 263 times its bulk. Forms white fumes, owing to moisture. 3-57. Supposed consti-tuents, Silicum. Fluorine. 5. Chlorocya-nic Acid. Oxyprussic Acid of Berthollet. Discovered by Berthollet. True nature made out by Gay-Lussac, 1815. Liquid. Colourless. Peculiar. Capable of com-bining with water. Cyanogen 26 one atom. Chlorine 36 one atom. 62 6. Sulphocya-nic Acid. Sulphuretted Chya-zic Acid of Porrett. Anthrazothionic Acid of Grotthuss. Porrett; 1808. Liquid. Colourless. Strong; like that of acetic acid. 1-022. Hydrocyanic acid 27 one atom. Sulphur 51 7. Ferrocyanic 1 Acid. 1 Ferruretted Chyazic Acid of Porrett. Porrett; 1814. Crystals. In solution, pale yel-low. None. According to Pon-ett. Carbon 24—four at. Azote 14—one at. Hydrogen 2—two at. Iron 28—one at. 68 V. Table of Acids, in which Oxygen and Hydrogen are both present. Names. From what substances usually obtained. Discoverers and time of discovery. State as to aggre-gation . Colour. Smell. Taste. Solubility. Eff cts of exposure to air. Specific Gravity. Effects of heat or cold. Composition. Weight of an atom of each. 1. Uric Acid. Certain urinary concretions. Scheele; 1776. Powder. White. None. None. Dissolves in 1720 parts of cold wa-ter, and in 1150 parts of hot. Decomposed when distilled. Azote 14—one atom. Carbon 12—two atoms. Hydrogen 1—one atom. Oxygen 8—one atom. 35 2. Purpuric Acid. Uric acid; by the action of nitric acid. Prout; 1818. Fine powder. Slightly yellowish. Very sparingly soluble. " 1 Acquires a: purplish 1 tint. By heat, be-comes purple and consumes. Azote 14—one atom. Carbon 12—two atoms. Hydrogen 2—two atoms. Oxygen 16—two atoms. 44 3. Gallic Acid. Oak-galls. The red Ant. Dijon Academicians; 1777. Crystals. Trans-parent. Unpleasant aromatic, when heated. Sour, with astringen-cy. Dissolves in 12 parts of cold wa-ter, and in 1*5 of hot. None. Carbon 11-8— Hydrogen 1*0—one atom. Oxygen 8-0—one atom. 21? 4. Formic Acid. Margraff; 1749. » Liquid. Sharp sour. Ml. Not crystalliz-able by cold. Carbon 12*0—two atoms. Hydrogen l-o—one atom. Oxygen 24*0—three atoms. 37? 5. Oxalic Acid. Sugar, Gum, Honey, &c. Bergman and Scheele. Crystals. Fine white with lustre. Very acid. Dissolves in 2 parts of cold wa-ter, and in 1 part ol'hot. None. By a gentle heat, loses wa-ter and falls to powder. Carbon 12*0—two atoms. Hydrogen 1-2— Oxygen 32*0—four atorai. 45? 6. Sorbic Acid. Juice of the berries of the Mountain Ash. 1 Donovan; 1815. Liquid. Colourless. None. Intensely sour. Carbon 11-7— Hydrogen 70—seven atoms. Oxygen 22*8—■ 43? 7. Succinic Acid. Amber. Boyle first remarked its acid properties. Crystals. White. Acid. Dissolves in 96 parts of cold wa-ter, and in 2 parts ot* hot. By a sand bath lieat, melts ami sublimes. Carbon 24-o—four atoms. Hydrogen 2-2— Oxygen 24H>—three atoms. 50? 8. "Vcetic Acid. ! Acetates, by dis-1 filiation. Volatile Liquid. 1 Extremely pungent and acrid. Combines with water in any proportion, j m„. .., .'When heated, Maximiiin',1 , c ' ,.„„ '.takei ore rea-1 °8- | dily. j Carbon 24-0—four atoms. 1 Hydrogen 3-»— 51? Oxygen 24-0—three atoms. Table of Acids, in which Oxygen and Hydrogen are both present—Continued. Names. From what Bubstances usually obtained. Discoverers, and time of discover)-. State as to aggre-gation. Colour. Smell. Taste. Solubility. Effctsof'g if exposure if,1 .„ .„ „•„ Gravity. to air. J Effects of beat or cold. Composition. Weight of an atom nt each 9. Tartaric Acid. Tartar. Scheele; 1770. Crystals. White. Exceed-ingly sour. Soluble. None. 1-59. Melts at a heat a little above the boil-ing point. Carbon 24-1— Hydrogen 2*6— Oxygen 40-0—five atoms 67? '10. Benzoic Acid. Benzoin. Fine light Powder. White. None, when pure. Sweet, hot and some-what bit-ter. Dissolves in 200 parts of cold water, and in 20-5 of hot. None. Carbon 29— Hydrogen 2—two atoms. Oxygen 8—one atom. 40? 11. Saclactic Acid. Sugar of milk and gum, by the action of nitric acid. Scheele; 1780. Gritty Powder. White. Slightly sour. Dissolves in 60 parts of boiling water. Carbon 34-8— Hydrogen 5-3— Oxygen 64-0—eight at. 105? 12. Citri* Acid. The juice ot oranges and lemons. Scheele. Crystals. Intensely sour. Dissolves in three-fourths of its weight of cold water, and iu half its weight of hot. None. When heated, first melts, and then emits an acrid vapour- Carbon 42-2— Hydrogen 3-9— Oxygen 56-0—seven at. 102? 13. Mellitic Acid. The mineral called mellite. Klaproth; 1799. Crystals. Brownish. At first sweetish-sour, then bitterish. Very soluble. Carbon. Hydrogen. Oxygen. 14. Camphoric Acid. Camphor. Kosegarten. 1785. Crystals. Snow-white. Like that of saffron. Slightly sour, and bitter. Dissolves in 96 parts of cold water, and in 11 parts of hot. Efflores-ces. When distil-led, first melts and then sub-limes. Carbon. Hydrogen. Oxygen. 15. Malic Acid. The juice of ap- ~ . , pies or of the Sc,h,teJe; house-leek. 17*5' Viscid Liquid. Beddish-brown. Very sour. Very soluble. In a dry air, be-comes like varnish. Carbon. Hydrogen. Oxygen. 16. Lactic Ac.d. The whey of milk. Scheele; 1780. Liquid. Brownish-yellow. Sharp sour, when heated. Sharp sour. When evapo-rated to dry-ness, appears like varnish. Carbon. Hydrogen. Oxygen. Table of Acids, in which Oxygen and Hydrogen are both present—Concluded. Names. From what substances usually obtained. Discoverer, and time of discovery. State as to aggregation. Colour. Smell. Taste. Solubility. Effects of exposure to air. Specific Gravity. Effects of heat or cold. Composition. Weiglit of an atom of each. 17. Pyrotarta-ric Acid. Tartar, by distillation. Crystals. Extremely sour. Readily solu-ble. By heat, melts, and sublimes in a thick stnoke. Carbon. Hydrogen. Oxygen. 18. Moroxylic Acid. The exudation on the bark of the mulberry. Klaproth; 1803. Crystals. Pale-wood. Like that of succinic acid. Soluble. None. Carbon. Hydrogen. Oxygen. 19. Suberic Acid. Cork. Brugnatelli; 1787. Powder, like starch. Sour, with-out any bitterness. Dissolves in 80 parts of cold water. By heat, melts and sublimes. Carbon.' Hydrogen. Oxygen. 20. Laccic Acid. Stick-lac- John. Crystals. Wine-yellow. Sour- Soluble. Carbon. Hydrogen. Oxygen. 21. Kinic Acid. Peruvian Baric. Vauquelin. Liquid. Brown. Sour and somewhat bitter. None. By heat, may be concentrated to the consistence of a syrup. Carbon. Hydrogen. Oxygen. 22. Zumic Acid. Vegetable substances, by fermentation. Bmmmuww Syrupy Liquid:. Colourless. Very sour. When distilled, converted into ace-tic acid and char-coal. Carbon. Hydrogen. Oxygen. 23. Boleut Acid. A species of Mushroom. Braconnot; 1811. Crystals. White. Like that ofbi tar-trate Of potash. Dissolves in 180 parts of cold water. None. When distilled, part sublimes. unaltered. Carbon. Hydrogen. Oxygen. DEFINITION AND CLASSIFICATION OF ACIDS 283 Chap, ill CHAPTER III. ACIDS DEFINED, AND THE CLASSIFICATION OF THEM PUR- SUED IN THE PRESENT WORK EXPLAINED. Having now finished the consideration of the acids, and given a tabular view of their properties, the reader is pre- pared to understand what is meant, in a chemical sense, by the term acid. The term acid, as used by the chemist, has a very dif- Definition ferent meaning from its common acceptation. In common ° language, this term is used as synonymous with sour; but when employed by the chemist, it is applied to a class of substances, which have either or both of the following pro- perties. 1. A sour taste. 2. The property of combining with certain compounds, called salifiable bases, with the effect of destroying their distinctive properties, as well as of losing their own. The second property mentioned may be considered as the most distinctive of acids. It is possessed by all this class of chemical bodies, except, perhaps, hydrocyanic (prussic) Acids of > acid, chloriodic acid and chlorocyanic acid. Chlorocarbonic character acid is found to be capable of neutralizing four times its enumerat- volume of ammoniacal gas; and although it is not known to eda be capable of combining with any other salifiable base; yet this one combination is sufficient to establish its acid nature. In strict propriety, perhaps, hydrocyanic acid should not stand among the acids. Acid properties were first attributed to it, under the influence of the erroneous opinion, that it is capable of neutralizing, or destroying the distinctive pro- perties of, salifiable bases. But it is now found, that it is always decomposed, when presented for combination with a salifiable base. Besides, it has not a sour taste, and is in- capable of reddening vegetable blues. Chloriodic acid, like hydrocyanic acid, suffers decompo- sition, whenever the attempt is made to combine it with a salifiable base. It does not redden vegetable blues, but des- troys them. Its taste has not been ascertained. Perhaps it would have been more correct to have adopted Gay-Lussac's opinion respecting its nature, and excluded it from the list of acids. Chlorocyanic acid is not known to combine with any sali- fiable base; but it reddens vegetable blues. It is certainlv 284 DEFINITION AND CLASSIFICATION OF ACIDS Book I. an acid of very doubtful character. So that it appears that Division II. two oUt Qf tjjC three acids, which are unable or not known to combine with salifiable bases, belong to the class of acids of irregular constitution, so called in this work. It is not improbable that further researches may make it necessary to strike out these combinations from the list of acids. Property of As to the property of reddening vegetable blues, which reddening js generally supposed to be distinctive of acids, it would vegetable ° , J. . rr , .. blues, not appear that it is mt rely a property, very generally associat- possesscd ed wjth the essential one of neutralizing salifiable bases. y aci s. por tkjg reason< jt js convenient to take the indications of acidity from it; and this course can lead to no error, when the chemist is acquainted with those acids, which do not possess this property. Having now considered the principal properties character- istic of the class of acids, and noticed those acids, which are of doubtful character; it is next proper to say something of the arrangement of these bodies, which has been adopted in this work. French After the chemistry of the French school had overturn- doctrine of erj the doctrines, connected with the supposed existence of and'acidifi- phlogiston or an inflammable principle; a fundamental doc- cation ex- trine of the new theory was, that oxygen is essential to the plained. production of combustion and acidity. It was contended, that, in every case of combustion, oxygen combines with the burning body, and separates from its light and heat; and that, when a body is acidified, it combines with oxygen, and in no case with any other substance. Found to The reader has already been put in possession of a suf- be errone- ficient number of facts, to enable him to determine that the French doctrine of combustion and acidification was erro- neous. This very evidently appears, when it is recollected that a plurality of supporters have been discovered, and that a number of acids are now known, into which oxygen does not enter as a constituent. The new The discovery of acids, into which oxygen does not enter viesrts- as a constituent, having destroyed the exact analogy, pre- di/cation*'' viously observed between the acids, a new arrangement of made a new them appeared to be absolutely necessary. A classification tio rcid °* *hem has been devised by Dr. Thomson; but it is too in- necessary, tricate to be of practical utility. The arrangement, which has been adopted in the present work, is founded upon the analogies in composition of the different acids. A number of acids, which have not oxygen as a consti- tuent, agree in containing hydrogen as a common principle. These acids are hydrochloric (muriatic) acid, hydriodic acid, hydrosulphuric acid (sulphuretted hydrogen), hydro- DEFINITION AND CLASSIFICATION OF AClDfe 285 fluoric (fluoric) acid and hydrocyanic acid. This striking fact Chap. hi. of the uniform presence of hydrogen in a number of im- ciassifica- portant acids, in which oxygen does not exist, suggested tion adopt- tht expediency of erecting a classification of these bodies, „p0n°"heed founded upon the presence or absence of oxygen or hydro- presence or gen in them. ox^Tno? Upon the presence or absence of oxygen or hydrogen, hydrogen. four classes of acids may be founded: I. Acids, in which oxygen is present, but not hydrogen. II. Acids, in which hydrogen is present, but not oxygen. III. Acids, in which neither oxygen nor hydrogen is present. IV. Acids, in which oxygen and hydrogen are both present. This, however, is not exactly the arrangement, which is adopted. Some of the acids, in which oxygen is present but not hydrogen, have bases, which are capable of forming acid compounds with hydrogen. This circumstance suggested the expediency of letting those acids stand in a class by themselves, whose bases form acid compounds, by combin- ing with oxygen or hydrogen indifferently. By this measure, acids whose bases are the same, are made to stand together. So that the arrangement, founded upon the presence or absence of oxygen or hydrogen, modified in the way just mentioned, gives rise to five classes: I. Acids, whose bases form acid compounds with oxygen or hydrogen indifferently. II. Acids, whose bases form acid compounds with oxy- gen only. III. Acids, whose bases form acid compounds with hy- drogen only. IV. Acids in which neither oxygen nor hydrogen is pre- sent. V. Acids, in which oxygen and hydrogen are both pre- sent. These classes, except the fourth, exhibit exactly the ar- rangement adopted. The fourth class, in the arrangement pursued, has the title of acids of irregular constitution. The acids which stand here cannot, indeed, be called acids, which contain neither oxygen nor hydrogen, although this is the case with some of them; so that, in this particular, the classification, founded upon the presence or absence of oxy- gen or hydrogen, has not been adhered to. The object of the classification, which has been adopted, is to afford a key to the memory for recollecting the consti- tuents of the different acids, by exhibiting their chemical relations to oxygen and hydrogen. With reference to the 286 SALTS. of th Book I. production of acidity, it would appear that chemical bodies P^f^liL arrange themselves in two sets; bodies called the bases of Theory of acids on the one hand, and oxvgen and hydrogen on the Uon^h'ich other- The concurrence of one body, at least, from each of leciVthe these sets, appears to be absolutely essential to the produc- dassifica- tion Qf aciditv. That this necessitv of concurrence is not uon adopt- imaginary^ but nz^ is evinced by this fact, that the bodies of neither set can produce acids by combinations among themselves.* Hence it is, that no acids, except those of doubtful character, are destitute of both oxygen and hy- drogen. , Advantages By the first class of acids, the fact is clearly shewn, that ~f*hear- chlorine, iodine, sulphur, selenium and tellurium are acidi- gC fiable by combining with either oxygen or hydrogen. The second class contains those acids, whose bases are acidifiable by oxygen only. These acids agree exactly in chemical con- stitution, and stand very well together. The third class con- tains the hydrofluoric (fluoric) acid and the hydrocyanic acid. The former has an undecompounded base, the latter, a compound base. Both these bases may be considered as acidified by hydrogen. The fourth class appears to contain a very proper association of acids. They are called acids of irregular constitution; and they are certainly irregular, with reference to any theory. Acids of the fifth class are those in which oxygen and hydrogen are both present. They are all, except the two first, triple compounds of carbon, hy- drogen and oxygen. In any arrangement of acids, they would necessarily stand by themselves. CHAPTER IV. OF SALTS. Salts are Having finished the consideration of acids and given compounds some account of their arrangement, the compound bodies, formed be- next tQ be considered, are those which are formed by the andesX union of acids and salifiable bases. These combinations arc bie bases. caued, by the chemist, salts. The salts will be treated of in as many classes as there are salifiable bases; those formed by each base constituting the subject of a separate section. * Some of the compounds, included under the class ofaeida of irregular consti- tution, are exceptions to this statement; but their composition is so imperfectly ascertained, that it is not unlike!j thut they may hewnfter prove to contain oxy gen or hydrogen. SALTS OF AMMONIA. 287 Chap. IV. SECTION I. SALTS OF AMMONIA. Salts of Ammonia are combinations of acids with the sa- Saltsofam- lifictble base ammonia. The most important of these salts ™JJta,jom. are the following. pounds. I. Chlorate of Ammonia.—Formerly called Hyperoxymu- Chlorate of riate of Ammonia.—This salt was first formed by Chenevix. smmonia- It m «y be prepared by dissolving carbonate of ammonia in chloric acid. The acid combines with the ammonia, and car- bonic acid is extricated. It is in the form of crystals of an exceedingly sharp taste. It is soluble in water. When thrown upon a burning coal, it detonates with a red flame. It is decomposed by heat; chlorine, azote and oxygen being evolved, and hydrochlorate of ammonia (sal ammo- niac), left behind. II. HYDROCHLORATE OF AMMONIA. Usual chemical name, Muriate of Ammonia.—Common name, Sal Ammoniac. 1. Hydrochlorate of ammonia may be formed either by Hydrochlo direct combination, or by decomposing sulphate of ammo- r?te; h°w nia by chloride of sodium (common salt). 2. Originally this salt was procured, in Egypt, from the soot of camels' dung, by sublimation. It is now made in great abundance in Europe by the direct union of its con- stituents, or by the decomposition of the hydrochlorates (muriates). 3. Hydrochlorate of ammonia is sometimes found native, especially in the neighbourhood of volcanoes. It has been known for several centuries. Its composition, however, does not appear to have been ascertained until the beginning of the last, when it was pointed out by Geoffroy, Junior. 4. In commerce, this salt occurs generally in the form of Properties. firm, round, elastic, concavo-convex cakes. But by solution and crystallization it may be obtained in crystals. It has a pungent, urinous taste, and, in the compact cake, is not alter- ed by exposure to air. Its specific gravity is 1*450. It is soluble, when in the cake, in somewhat more than three times its weight of cold water, and in its own weight of boiling water. In crystals, it requires less water for its solu- tion. When heated, it sublimes unaltered, emitting a pecu- liar odour. 5. Hydrochlorate of ammonia, has the property of form- Combines ing a permanent compound with perchloride of mercurywith ?er'- (corrosive sublimate). This compound was called by the mS!Sr. 288 SALTS D??°.K *• alchemists sal alembroth, and is usually called bv chemists lVn?2__" a muriate of mercury-and-ammonia, under an ide.i th.it it is a triple salt. According to the new chemical views re- specting the nature of oxymuriatic acid (chlorine), it can- not be considered as a salt. When a solution of carbonate of potash or of soda is added to a solution of this com- pound, there falls a precipitate, which is the ammoniated perchloride of mercury, noticed under the head of the per- chloride, page 106. 6. Hydrochlorate of ammonia is composed of Hydrochloric acid 37—one atom. Ammonia 17—one atom. Composi Horn. Giving 54 for the number repre- senting the weight of its atom. Medical 7. This salt was formerly used in medicine as an aperient properties, and attenuant; but, at the present day, it is never given in- ternally. Externally, it is used in solution for the purpose of removing chronic inflammation, and as a discutient in indolent tumours. It appears to act at first by the cold which it produces, and afterwards, as a stimulant, by creating a new and more healthy action. III. Iodate ofAmmonia.—--This salt maybe formed by sa- turating iodic acid with ammonia. It is in the form of crys- tals, which detonate when thrown upon heated coals, emit- ting a weak violet light and giving out vapours of iodine. IV. Hydriodate of Ammonia.—This salt may be formed by mixing together equal volumes of hydriodic acid gas and ammoniacal gas; or by dissolving liquid ammonia in a solution of hydriodic acid. It is in the form of crystals, which are soluble in water and deliquescent in the air. V. SULPHATE OF AMMONIA. Secret Sal Ammoniac of Glauber.— Vitriolated Ammoniac. Sulphate of 1. This salt may be prepared by saturating ammonia with 1 sulphuric acid, or by decomposing hydrochlorate of ammo- nia by means of the same acid. It has a sharp bitter taste. It is soluble in twice its weight of cold water, and in its own weight of boiling water. In the air, it slowly attracts moisture. 2. It is formed by manufacturers from the impure liquid sub-carbonate of ammonia, obtained by distilling bones and other animal substances, by saturating it with sulphuric acid; or more economically, by double decomposition be- tween it and sulphate of lime (gypsum). It js procured by them to be employed afterwards in the manufacture of hy- drochlorate of ammonia (sal ammoniac), by double decom- position with chloride of sodium (common salt). prepara tion. How ob- tained by the manu facturer. SALTS OF AMMONIA. 289 VI. Sulphite of Ammonia.—The taste of this salt is cool- Chap, iv. ing and penetrating,and leaves a sulphureous impression in "" the mouth. It dissolves in its own weight of cold water, with the production of cold. Exposed to the air, it attracts moisture and is converted into a sulphate. VII. HYDROSULPHATE OF AMMONIA. ' Usual chemical name Hydrosulphuret of Ammonia. 1. This salt may be obtained perfectly pure by causing Hydrosul- hydrosulphuric acid gas and ammoniacal gas to pass into P^jj^. a bottle surrounded with ice. It is in the form of transpa- how obtairi- rent and colourless crystals. It is very volatile, and when ed- kept in a bottle sublimes gradually to the top. U. For medical employment, it may be formed by passing a current of hydrosulphuric acid gas, through liquid ammo- nia. The solution of the salt, which is thus formed, is of a greenish-yellow colour. 3. This salt was first used in medicine by Cruickshank. Its action It acts very powerfully upon the living system, inducing^n^ys" vertigo, drowsiness, nausea and vomiting, and lessening the tem. action of the heart and arteries. It has been used, in solution, in diabetes by Dr. Rollo and others, in doses of from five to ten drops twice or thrice a day. Its activity entitles it to the notice of practitioners. VIII. Hydrosulphite of Ammonia.—Usual chemical name Hydrosni- Hydroguretted Sulphuret of Ammonia.—This salt may be phlle obtained by pouring hydrosulphate of ammonia upon sul- phur. The fuming liquor of Boyle is a hydrosulphite of am- monia with excess of base. This liquor may be prepared by distilling a mixture of equal parts of hydrochlorate of ammonia, sulphur and lime. It is a liquid of a deep-orange colour, which constantly emits white fumes of a strong am- moniacal and fetid odour, owing to the excess of its base. When allowed to stand, it gives off this excess, whereby its fuming property is destroyed, and deposites a portion of sul- phur, sufficient to reduce its acid to the state of hydrosul- phuric acid. In this way, it becomes converted into a hy- drosulphate of ammonia. IX. Nitrate of Ammonia.—Old names, Nitrum Semivo- Nitrate. latile; Nitrum Flammans.— This salt may be prepared by dissolving carbonate of ammonia in dilute nitric acid, and allowing the solution to stand until crystals form. These crystals constitute the salt in question. It has a very acrid, bitter, disagreeable taste. It is soluble in twice its weight of cold water, and in half its weight of boiling water. When exposed to the air, it attracts moisture, and deliquesces. When subjected to a heat, not exceeding 500°, it is whollv 2 O 290 SALTS. of ammo- nia. Book l converted into protoxide of azote (nitrous oxide) and water. Divismn IT. jt js from t^js sa^ t^ai ^^ protoxide is usually obtained. When exposed to a heat above 600°, it is totally decom- posed, and converted into deutoxide of azote (nitrous gas), nitrous acid, water and azote. X. CARBONATE OF AMMONIA. (Formerly called, Prepared Ammonia.—Mild Volatile Alkali.) Carbonate 1. This salt mav be prepared by subliming a mixture of two parts of pure carbonate of lime (chalk) and one part of hydrochlorate of ammonia (sal ammoniac) both in powder, and made as dry as possible. The sublimed product is car- bonate of ammonia. Prepara- 2. Carbonate of ammonia is obtained, by the manufac- tionofthe turer, by the destructive distillation of animal substances, impure . ^ carbonate which contain azote. The substances generally employed by the ma- are refuse bones and horns. The distilled products are 'water, subcarbonate of ammonia and empyreumatic oil. Water is first driven over; then the subcarbonate, which dissolves in the water to the point of saturation and after- wards concretes in the upper parts and sides of the receiver, and lastly the oil. These three products are respectively called the volatile liquor, salt and oil of hartshorn. The vo- latile liquor and the salt contain a portion of the oil, which adheres obstinately, while the oil holds in solution a por- tion of the salt. None of these products, except the water, pre-exist in the distilled substance; they are all formed, during the process, by a new arrangement of its ultimate constituents. Azote and hydrogen combine to form ammo- nia, carbon and oxygen, to form carbonic acid, and carbon, oxygen and hydrogen, to form oil. The volatile liquor and salt of hartshorn are too impure for use in medicine. The carbonate of ammonia, which they contain, may be saturated with sulphuric acid; and the sul- phate thus formed is employed in the manufacture of hy- drochlorate of ammonia (sal ammoniac) by the agency of chloride of sodium (common salt), as already mentioned under the head of the sulphate. A hydrochlorate being thus obtained, it may be converted into a pure carbonate in the manner detailed in the first paragraph. Properties. 3. Carbonate of ammonia is in the form of a white crys- tallized mass of a fibrous texture, having the smell and taste of pure ammonia, but much weaker. It is soluble in twice its weight of cold water. In boiling water, it is volati- lized. Its specific gravity is 0*966. Water of 4. The solution of carbonate of ammonia is officinal, ofammo- una Book I. 4. They are not volatilized, when exposed to a red heat, IV'SI0"11, as is the case with the salts of ammonia. When they contain a combustible acid, such acid is decomposed, and the resi- due, after the heat is withdrawn, is carbonate of potash, mixed with a little charcoal. When their acid is not com- bustible, they fuse without suffering decomposition. To this, however, there are several exceptions; the acid of the nitrate is decomposed at a red heat; and, at the same tem- perature, the sulphite becomes a sulphate, sulphur being sublimed. 5. They let fall an orange-coloured precipitate, when treated with a solution of platinum. SECTION III. SALTS OF SODA. Salts of so- Salts of soda are compounds of the different acids with compounds l^e salinaDle base soda. The following are the most im- portant of these salts. Chlorate of I. Chlorate of Soda.—Former chemical name, Hyperoxy- soda- muriate of Soda.—This salt may be formed by dissolving carbonate of soda in chloric acid; or by passing a current of chlorine through a solution of the same salt. It is in the form of crystals, of a sharp, cooling taste. When placed on burning coals, it melts into globules, and produces a yellow light. No hydro- II. Hydrochlorate of Soda does not exist. When the Cod°ratC °f attempt *s made to combine hydrochloric acid with soda, a double decomposition takes place; the hydrogen of the acid combines with the oxygen of the soda and forms water, while the chlorine of the former and the sodium of the latter unite and form a chloride. This chloride (com- mon salt) was formerly supposed to be a muriate (hydro- chlorate) of soda. It has already been described in a pre- ceding part of this work. III. Iodate of Soda.'— This salt may be formed by dis- solving iodine in a solution of soda. It is in the form of crystals, soluble in about 14 times their weight of cold wa- ter. When heated sufficiently, it gives out 24$ per cent, of oxygen gas, and is converted into iodide of sodium. IV'. Hydriodate qf Soda.—This salt may be formed by dissolving carbonate of soda in hydriodic acid. It is in the form of large deliquescent crystals, which contain a good deal of water of crystallization. SALTS OF SODA. 311 V. SULPHATE OF SODA. CHAP IV (Common names, Glauber's Salt.—Vitriolated Natron.—Vitriolated Fossil ^ Alkali.) 1. This salt may be formed by saturating carbonate of Sulphate of i • -j soda. soda with sulphuric acid. 2. It is obtained by the manufacturer, most generally, How pre- from the residuum of the process for obtaining hydrochlo- P^J^ rate (muriate) of ammonia, by,the mutual action of sul- waey. ° phate of ammonia and chloride of sodium (common salt). It may be obtained, economically, by making into a paste with a sufficient quantity of water, eight parts of burnt sul- phate of lime (gypsum)j five parts of clay, and five parts of chloride of sodium (common salt). This mixture is burnt in a kiln or oven, then ground to powder, and afterwards treated with water, and evaporated until crystals of sulphate of soda form. 3. This salt has been found native, in large quantities, in Persia, Bohemia and Switzerland. 4. Sulphate of soda is in the form of crystals, possessing Properties. a taste at first salt, but becoming afterwards nauseous and bitter. It is soluble in 2*86 parts of cold water, and in 0*8 parts of boiling water. When heated to redness and thus deprived of its water of crystallization, it requires 3*3 parts of water, at the temperature of 144°, for its solution. When exposed to the air, it falls into a white powder, and loses about half its weight in water of crystallization. When sub- jected to a heat gradually increased, it first undergoes the aqueous and afterwards the igneous fusion. 5. This salt, when anhydrous,* is composed of SlnT*1" Sulphuric acid 40—one atom. Soda 32—one atom. Giving 72 for the number representing the weight of its atom. 6. This salt is by far the most commonly used of the Medical saline purgatives. When taken in a dose of from half an properties. ounce to an ounce or more, it is a mild, but effectual cathartic. When given in smaller doses, largely diluted, it acts as an aperient and diuretic. When in a state of efflor- escence, the dose should be reduced to one-half. VI Hydrosulphate qf Soda.—Usual chemical name, Hy- Hydrosul- drosulphuret of Soda.—This salt may be prepared by the Phate- same processes as the hydrosulphate of potash. It is in the form of transparent and colourless crystals of an alkaline and intensely bitter taste. It is very soluble in water. When ex- * An anhydrous salt is one in which no water exists, 312 SALTS Hydrosul phite. Nitrate. Book I. posed to the air, it deliquesces and assumes a green colour. Division H. jt is decomposed by acids, hydrosulphuric acid gas being evolved. VII. Hydrosulphite of Soda.—.Usual chemical name, Hy- droguretted Sulphuret oj Soda.—This salt may be obtained by the same process as the hydrosulphite of potash. It is of a deep-red colour, inclining to brown. Its taste is acrid, and, as it were, bitter and cooling. It stains the skin of a deep- green colour. When kept in close vessels, it deposites sul- phur, becomes colourless, and is converted into hydrosul- phate of soda. VIII. Nitrate of Soda.—Formerly called Cubic Nitre.— This salt may be iormed by the direct combination of its constituents, or, by double decomposition, from nitrate of lime and sulphate of soda. It is in the form of transparent crystals of a cool sharp taste, somewhat more bitter than that of nitrate of potash (nitre). It is soluble in about three parts of cold water, and in less than its own weight of boiling water. When exposed to the air, it attracts mois- ture. It exhibits the same phenomena as the nitrate of pot- ash when exposed to heat, except that it does not melt so easily. It is composed of Nitric acid 54—one atom. Soda 32—one atom. Giving 86 for the number represent- ing the weight of its atom. Carbonic acid combines in two proportions with soda, and forms carbonate and bicarbonate of soda. IX. CARBONATE OF SODA. Common names, Prepared Natron.—Mild Fossil Alkali. 1. This salt may be obtained from impure carbonate of soda (Spanish barilla) by solution in boiling water, filtration and evaporation. Crystals of this salt will be found de- posited. . . 2. The carbonate, here used, is a fused mass, consisting principally of carbonate of soda, but containing also char- coal, earthy substances, and some salts. The insolubility of the charcoal and earthy substances, renders it easy to sepa- rate them. The foreign salts are separated by taking ad- vantage of their different solubility in hot and cold water, when compared with that of the carbonate. 3. Carbonate of soda of commerce has two principal sources in nature. It is obtained from the ashes ot certain marine plants, and from chloride of sodium (common salt) and sulphate of soda, by chemical decomposition. It may be Soda forms two salts with car- bonic acid. I. Carbo- nate of soda; how obtained pure. Impure carbonate of com- merce; its sources. SALTS OF SODA. 313 obtained also by exposing bicarbonate of soda, which is Chap.IV. found native, to heat. [1] The marine plant, from which carbonate of soda isHowob- most usually obtained, is the salsola soda; but there are ^i^etrom several other plants, which yield it in considerable abun- plants. dance. The proper plants are cultivated in salt marshes by the Spaniards. They are cut down, dried like hay, and formed into bundles. Several of these bundles are set on fire and thrown into a deep pit. After they are in a state of complete combustion, others are thrown in from time to time, until the pit is fulL After the incineration is complete, the impure carbonate of soda is obtained in a solid mass, and dug out and broken into pieces. The impure carbonate of soda, thus prepared, is called Forms ba- barilla in commerce. When of good quality, it is firm, r'l,a wJje.n • 11 1 ° i- 11 c 11 thus obtain- hard, heavy, dry, sonorous, spongy, and internally 01 a blue ed. colour, mixed with white in spots. When the impure carbonate is prepared from different when ob- species of fuci, it is called kelp in England and America, j*ined by and varec by the French. It is much more contaminated fuc^caUed with foreign matters than the barilla of Spain. ke|p atld [2] Chloride of sodium (common salt) may be decom- (j^bonate; posed, so as to yield carbonate of soda by the agency of howobta'm- three substances; namely, semi-vitrified oxide of lead (li- ^J^f" tharge), lime and iron. chloride of When four parts of semi-vitrified oxide of lead and onesodlum- part of chloride of sodium are pulverized, mixed together and macerated in water for several hours, a mutual decom- position takes place: water is decomposed; hydrochloric (muriatic) acid is formed, which combines with the pro- toxide of lead, in the form of an insoluble subhydrochlorate, while the carbonic acid, which exists in the semi-vitrified oxide, combines with the sodium, previously converted into soda, and forms carbonate of soda. When a mixture of chloride of sodium and lime is form- ed into a paste with water, and left in a moist situation, a decomposition takes place, and there is formed chloride of calcium (muriate of lime) and carbonate of soda. The carbonic acid is obtained from the atmosphere. Carbonate of soda, however, is not manufactured by means of lime. A manufactory by this process was about to be established in France in 1782; but it appears never to have gone into operation. Carbonate of soda is not extracted in the large way by means of iron; but the fact, that it might be obtained in this way, was ascertained by Scheele, who found that a piece of iron suspended in a cellar for fourteen days, after having 2R 314 SALTS. Book I. been dipped into a solution of chloride of sodium (common Division II. sajt^ became incrusted with carbonate of soda. It has been proposed to decompose chloride of sodium by means of acetate of lead (sugar of lead); or by the salt formed by combining the semi-vitrified oxide of lead (li- tharge) with the acid liquor obtained by distilling wood. An acetate of soda is formed in either case, which is to be exposed to a strong heat, whereby the acetic acid is p r- tially converted into carbonic acid, and the salt itself, chang- ed into a carbonate. Carbonate [3] Sulphate of soda may be decomposed so as to yield may be ob- carbonate of soda, 1. By carbonate of potash; 2. By acetate sTphtteof of lime; 3. By semi-vitrified oxide of lead (litharge); 4. soda; By charcoal. j B The decomposition by carbonate of potash is effected, in means of the large way, by the following process. A boiling saturat- of^otaslr ed solution of 56° pounds of impure carbonate of potash (potashes) is ladled into a boiling solution of sulphate of soda. They are agitated together, and again quickl\ heated to ebullition. The liquid is next drawn off into wooden cis- terns lined with thick sheet-lead, and allowed to cool at a temperature not exceeding 55°. After the salt has deposited, the remaining liquor is drawn off from it, and it is washed with cold water, and afterwards boiled with clean water. This second solution is evaporated at a low red heat, until pellicles of sulphate of potash no longer form on its surface. The fire is then withdrawn, and the solution is allowed to cool pretty low, when it is ladled out into the cistern to crystallize. 2. By ace- When the carbonate is obtained from the sulphate of tateoflime; soda by acetate of lime, the latter salt, with a view to economy, is formed by combining the impure acetic acid, obtained in the distillation of wood, with lime. When the acetate of lime is mixed with the sulphate, a double de- composition takes place, and acetate of soda and sulphate of lime become formed. The acetate, by being exposed to a strong heat, has its acid changed, and becomes converted into carbonate of soda. 3. By li- When the semi-vitrified oxide of lead is used to decom- tharge;andp0se the sulphate, by the mutual decomposition of these two substances a carbonate of soda becomes formed at once. 4. By char- When the sulphate is decomposed by charcoal, the car- °oa'- bonate becomes formed in consequence of the power, which this combustible possesses, of decomposing sulphuric acid at a high temperature. The process, in the large way, is to grind together 500 pounds of sulphate of soda and 100 pounds of charcoal, and to expose the mixture formed to SALTS OF SODA. 315 the heat of a reverberatory furnace, until it becomes pasty. Chap, iv. It is then transferred to large casks, where it is lixiviated, evaporated and crystallized. The carbonate of soda, when carefully prepared by means of any of the decompositions just mentioned, becomes suf- ficiently pure to be used in medicine and the arts. This, however, is not the case with the carbonate, obtained by the incineration of marine vegetables (barilla). 4. Carbonate of soda is in the form of large and beauti- Properties ful crystals, possessing a taste precisely similar to that of nate^f carbonate of potash. Its specific gravity is 1*35. It is soluble soda. in two parts of cold water, and in rather less than its weight of boiling water. When exposed to the air, it effloresces and falls to powder. When subjected to a heat gradually increased, it first undergoes the watery fusion, next becomes dry, and afterwards suffers the igneous fusion and assumes the appearance of a transparent liquid. After this has taken place, if the heat be further urged, part of its acid is driven off. It contains in crystals nearly 65 *>cr cent, of water, which is driven off when the salt is dried by heat. 5. It is composed of Composi- f- , . , t«®n. Carbonic acid 22—-one atom. Soda 32—one atom. Giving 54 for the number represent- ing the weight of its atom. 6. In medical properties, carbonate of soda is verv simi- Its medical lar to carbonate of potash; but in many respects it is pre- ferable to this salt. Its form of permanent crystals enables its dose to be better regulated; and after efflorescence it may be exhibited in the form of pills. In this litter state, it forms the officinal preparation called dried carbonate of soda. This is best prepared by exposing the pounded cr\ stals before the fire, and not, as the Dublin college directs, by subjecting them to heat, until they undergo the aqueous fusion and af- terwards become dry. The effloresced carbonate of soda was first recommended by Dr. Beddoes, as a substitute for the supercarbonated alkaline waters, when the latter did not agree with par- ticular constitutions. It has a very powerful operation on the urinary organs, and is by far the most efficacious re- medy known in a majority of cases of calculus, sometimes removing the disease entirely, and almost always alleviating and palliating the symptoms. If the doctrine of the chemical physicians be correct, the carbonates of potash and of soda exert their power in calcu- lous cases, in which the uric acid is most abundant. Now 316 SALTS. Book I. it has been found by chemists, that more than one-half the Division II. caicvlli^ which have come under their notice for analysis, are composed of uric acid, either alone or combined with ammonia. The effloresced carbonate of soda may be given to the extent of one or two scruples or more during the 24 hours, made up into pills with soap. X. BICARBONATE OF SODA. 2 Bicarbo- !• This salt may be formed by exposing a solution of nate of carbonate of soda to an atmosphere of carbonic acid gas. It soda; oc- . ,.. , * ., ° , curs native ls an uncrystalhzed mass, possessing a taste similar to the in Africa in carbonate, but much milder. It contains about 23 per cent. masses. Q£ water# jt occurs native in considerable quantities in Africa, in the province of Sukena, near Fezzan, and is called trona by the natives. It was not distinguished from the carbonate of soda of commerce until 1802, when Klap- roth pointed out its distinguishing properties. It is in the form of striated masses, not altered by exposure to the air, and so hard that it is said that the walls of a fort in Africa, now in ruins, was built of it.' Composi- 2* II is composed of tion. Carbonic acid 44—two atoms. Soda 32—one atom. Giving 76 for the number repre- senting the weight of its atom. The native bicarbonate, how- ever, contains somewhat less carbonic acid. Medical 3* This ssi^t m solution constitutes the water of super- properties, carbonate of soda of (he Edinburgh college. It is prepared by saturating a very dilute solution of carbonate of soda with carbonic acid, made to pass through it in a stream. This solution is more pleasant, and may be taken to a greater extent, than the solution of the carbonate. Soda forms Boracic acid combines in two proportions with soda, and two salts forms borate and subborate of soda. The subborate will with bora- , , ., , r cic acid. "e described first. XL SUBBORATE OF SODA. Common name, Borax. l. Subbo- 1. This salt is extracted from tincal, a substance which elutsfm°da; comes from the East Indies, by repeated solutions, filtrations the waters and crystallizations. It exists in the waters of certain lakes UkeY1*"1 and wells'to be found in Thlbet and China. These waters are evaporated, and the salt obtained in an impure state, in- termixed with sand, small stones and other impurities, when it is called tincal. In this state it occurs in commerce. SALTS OP SODA. 317 m masses, composed of a few large crystals, but chiefly of chap, rv. small ones, possessing a colour, partly white and partly green, with an appearance as if joined together by a greasy yellow substance. 2. Subborate of soda (borax) was known at least as early as the tenth century; nevertheless it was a long time before its chemical nature was ascertained. In 1712, Homberg discovered boracic acid as one of its constituents, and, without being aware of its acid nature, gave it the name of sedative salt. It was not until fifty years afterwards that Baron demonstrated that its base was soda. 3. Subborate of soda is a crystallized salt of a white its proper- colour, and styptic, alkaline taste. It possesses the property &<*. of changing vegetable blues to green. It is soluble in twenty parts of cold water, and in six parts of boiling water. In the air, it effloresces slightly. When heated, it loses nearly half its weight in water of crystallization, and assumes the form of a light, porous, very friable mass, called calcined borax. In a stronger heat, it melts into a transparent glass, without losing its solubility. It has been long familiar to artists, as a flux, to facilitate the fusion of the precious me- tals, and for its use in the formation of imitations of the pre- cious stones. 4. The medical properties of subborate of soda have Medical been but very little investigated. It is rarely given inter- uses nally. It is said to possess the properties of a diuretic and emmenagogue. It is employed in solution, or mixed with white sugar, to cleanse the mouth and fauces of infants, when these parts are affected with aphthae. Upon the whole, it seems to deserve more notice than is generally given to it by physicians. XII. Borate of Soda.—-This salt may be formed by satu- 2. Borate of rating subborate of soda with boracic acid. It has been but toi*' very imperfectly examined. , Phosphoric acid combines in two proportions with soda, Soda forms and forms phosphate and biphosphate of soda. ^th^hos- XIII. PHOSPHATE OF SODA. phoric aeid Wonderful Perlated Salt of Haupt. 1. Dr. Pearson gives the following formula for the pre- i. Phos. paration of this salt. To a solution of 1400 grains of crys- Phate °f tallized carbonate of soda in 2100 grains of water, placed ** in a long necked matrass, add, gradually, 500 grains of phosphoric acid of the specific gravity of 1*85. Boil the liquor for a few minutes, filtrate it while hot, and pour it into a shallow vessel, which must be placed in a cool situa- 318 SALTS. Book I. tion. During the course of several days, crystals of phosphate P^jo^of soda will be deposited. Prepara- 2. Phosphate of soda is prepared by the apothecaries by anothV1"5 treat*ng burnt bones (phosphate of lime) with sulphuric ries. acid. This acid partially decomposes the phosphate, and forms with the base of the decomposed portion, an insolu- ble sulphate of lime (gypsum), while the disengaged phos- phoric acid combines the undecomposed portion, and iorms a superphosphate of lime, which remains in solution. The sulphate of lime is separated by the filter, and the remain- ing solution, containing the superphosphate, is decomposed by a solution of carbonate of soda. The carbonate, how- ever, does not decompose the superphosphate completely; but its base combines with the excess of acid in this salt, and forms a phosphate of soda, which remains in solution, whereby the soluble superphosphate becomes reduced to the state of an insoluble phosphate. The phosphate of lime is now separated by the filter, and by treatment again with sulphuric acid and carbonate of soda may be made to yield a new portion of phosphate of soda. The solutions of phosphate of soda, thus obtained, are next evaporated until they deposite crystals. Exists in 3. This salt exists ready formed in urine; but as it would unne. not yield phosphorus when treated with charcoal, it was suspected to contain an acid different from the phosphoric. Proust supposed he had obtained this acid, to which he gave the name of perlated acid; but the substance obtained by him was afterwards proved by Klaproth to be a phosphate of soda with excess of phosphoric acid, that is, a biphosphate of soda. 4. Phosphate of soda is in the form of crystals, possess- ing a cooling and urinous, but not disagreeable taste. It is soluble in about four parts of cold water, and in two parts of boiling water. Its specific gravity is 1*3;>3. It contains about 62 per cent, of water of crystallization. When ex- posed to the air, it effloresces on the surface. When sub- jected to heat, it first undergoes the watery fusion, and afterwards, when it has reached the point of redness, melts into a white enamel. Before the blow-pipe, it fuses into a transparent globule, which becomes opaque upon cooling. It is not altered by combustibles or metals. With most of the metallic oxides, it fuses into a coloured glass. It is p.irtially decomposed by hydrochloric (muriatic), sulphuric and nitric acids, and converted into a biphosphate. Its medical 5. Phosphate of soda was introduced into the practice of properties, medicine, as a purgative, by Dr. Pearson. It possesses the same medical properties as sulphate of soda (Glauber's Its proper ties. SALTS OF SODA. 3 \g salt), but it has this advantage over the sulphate, that it is Chap. IV. much less disagreeable to swallow. The dose is eight or~ ten drachms. It may be given very conveniently in soups, to which it imparts a taste, very similar to that occasioned by chloride of sodium (common salt), and not unpleasant to the most delicate palate. XIV. Biphosphate of Soda is a soluble salt not easily 2. Biphos- crystallized. It may be obtained in thin scales, not unlike p " boracic acid. It was this salt, which Proust supposed to be the acid of the phosphate. XV. Ammonio-phosphate qf Soda.—-Old names, Micro- Ammonio- cosmic Salt; Fusible Salt of Urine—It was a long time Pha°spb^.ex. known that this salt might be extracU d from urine, before traeted any correct notions of its chemical composition were form- from unne ed. Margraff showed that it contained ammonia, and might be made to yield phosphorus; but it was Fourcroy, who first subjected it to a precise analysis. Its properties are those, very nearly, of phosphate of soda and phosphate 01 ammonia, joined together. When subjected to heat, its am- monia is driven off, and the salt is converted into a super- phosphate. When exposed to the air, it suffers efflorescence and graduallv loses its ammonia. XVI. Hy^rojluate of Soda.—Usual chemical name, Fluate of Soda.—This salt may be formed by pouring a solution of soda into hydrofluoric acid. A combination takes place with the evolution of much heat. It is in the form of small crystals, soluble in water, and not altered by exposure to air. When heated, it decrepitates, and afterwards undergoes the igneous fusion. XVII. Silicqfluate of Soda.—Fluosilicate of Soda of Dr. Thomson.—Scheele affirms that this salt may be formed by the same means as the silicofluate of potash; but Gay-Lus- sac and Thenard could obtain the hydrofluate (fluate) of soda only, the salt described in the preceding paragraph. XVIII. Sulphocyanate of Soda.—This is a crystallizable deliquescent salt. XIX. Ferrocyanate qf Soda.—Formerly called, Triple Ferrocya- Prussiate of Soda; Prussiate qf Soda-and-Iron.— This salt JJ^j may be formed by a process similar to that given for the preparation of the ferrocyanate of potash. It is in the form of transparent crystals, of a yellow colour and bitter taste. When exposed to the air in a warm place, it falls to powder, and loses 37$ per cent, of its weight. It is soluble in 4| parts of cold water, and in a much smaller quantity of boiling water. Its specific gravity, when in crystals, is 1-458. XX. Urate qf Soda.—The concretions, called chalk-Urate. 320 SALTS Book l stones, which form in joints long affected by gout, arc Division II. found to consist entirely of this salt. XXI. Acetate of Soda.—Formerly called, Crystallized fo- liated earth.—This salt is usually prepared by saturating acetic acid with carbonate of soda, and evaporating the so- lution until a pellicle forms on its surface. Upon cooling, crystals of acetate of soda are deposited. This salt has a sharp taste, approaching to bitter. It is not affected by ex- posure to air. It is soluble in nearly three parts of cold water. When heated, it first loses its water of crystalliza- tion, which amounts to about 40 per cent, and afterwards melts, if the heat be sufficiently urged. sodatrate°f XXI1* Tartrate of Soda___This salt may be formed by dissolving carbonate of soda in tartaric acid. It is in the form of needle-shaped crystals, soluble in about their weight of cold water. It is capable of combining with an excess of acid, forming a salt nearly as insoluble as the bitartrate of potash (cream of tartar). It is composed of Tartaric acid 67—one atom. Soda 32—one atom. Giving 99 for the number representing the weight of its atom. XXIII. TARTRATE OF POTASH-AND-SODA. (Common name, Rochelle Salt.—Formerly called, Salt of Seignette.) Tartrate of l. This salt is usually prepared by adding gradually, as soda! how ^on8 as effervescence occurs, carbonate of soda to a solution prepared, of one part of bitartrate of potash (cream of tartar) in five parts of boiling water; and afterwards, when the saturation is complete, filtering the solution, and evaporating it to the consistence of a syrup. Upon cooling, it deposites crystals of tartrate of potash-and-soda. In this process, the salt be- comes formed in consequence of the soda of the added car- bonate saturating the excess of acid in the bitartrate. 2. This salt was first formed, and introduced into the practice of medicine, by Mr. Seignette, an apothecary at Rochelle, by whose name it was formerly generally known. For some time its composition was kept secret. In 1731, however, Boulduc and Geoffroy ascertained its chemical nature. Properties. 3. Tartrate of potash-and-soda is in the form of large crystals, permanent in the air, and soluble in five times their weight of water. It has a bitter taste. When exposed to heat, it suffers decomposition. Its specific gravity is 1*757. SALTS OF SODA. 321 4. It is composed of Chap. IV. Tartrate of potash 115—one atom. Tartrate of soda 99—one atom. Giving 214 for the number represent- ing the weight of its atom. 5 This salt is frequently used as a purgative. It is not Medical so disagreeable to take as sulphate of soda, but more sous than the phosphate; and it has this disadvantage, that it re- quires to be given in a larger dose than either of these salts. Of the remaining salts of soda, the ammonio sulphate, List of salts sulphite, selenate, h\ pophosphite, arseniate, arsenite, chro- Jj™^™* mate, molybdate, tungstate, purpurate, formate, oxalate, so?bate, succinate, benzoate, lactate, citrate, mellate, cam- phorate, malate, saclactate and suberate have been formed, and more or less accurately described, by chemists; but they are of too little importance to be described. The rest of the salts of soda, amounting in number to 24, are unknown. The salts of soda may be known by the following pro- General properties perties. of the salts 1. Thev are all soluble in water, and much more so than 0f soda. the salts of potash. 2. When exposed to heat, they undergo the aqueous fusion, by reason of the large quantity of water of crystal- lization which they contain. If the heat be continued, the water is dissipated, and they assume the form of a dry white powder. When the heat is increased to redness, if the acid present in them be combustible, it is destroyed; if volatile, it is driven off; but if fixed, the whole undergoes the igneous fusion, and, on cooling, assumes the appearance of an opaque white mass, usually destitute of water. 3. Their solutions are neither precipitated by tartaric acid, nor enabled to deposite crystals of sulphate of potash- and-alumina (alum), by the addition of sulphate of alumina. These last mentioned marks distinguish them very com- pletely from the salts of potash. 2 S 322 SALTS. Book I. Di™on "■ SECTION IV. SALTS OF LITHIA. Salts of U- Salts of Lithia are combinations of acids with the sali th,a:J*haH. fiable base lithia. In consequence of the recent discovery compounds. . » _ , , , , of this substance, very few of these salts nave been exa- mined. The following are the principal ones, which have been described. Sulphate of I. Sulphate of Lithia.—This salt may be obtained from fithia. petalite, by exposing the mineral in powder for 2\ hours to heat, along with carbonate of barytes; dissolving off the excess of the barytes by hydrochloric acid added in excess, and precipitating the remainder of this substance by an excess of sulphuric acid. After the insoluble sulphate of barytes 'i6 separated, the remaining liquid will be a solution of the sulphate of lithia, containing alumina. Precipitate the alu- mina by carbonate of ammonia, and evaporate to dryness: the dry mass consists of this sulphate. It is a very soluble salt, possessing a purely saline taste. It suffers no change in the air. It is composed, in whole numbers, of Sulphuric acid 40—one atom. Lithia 18—-one atom. Giving 58 for the number represent- ing the weight of its atom. Nitrate. II. Nitrate of Lithia.—This salt is deliquescent, and possesses a taste like nitrate of potash (nitre). When heated, it fuses into a liquid, running like water. Carbonate. III. Carbonate of Lithia.—This salt may be formed by decomposing the sulphate of lithia by acetate of barytes. In this way there becomes formed an acetate of lithia. This acetate, by being heated to redness in a platinum crucible, has its acid decomposed, and is converted into a carbonate. Carbonate of lithia has an alkaline taste. It restores the colour of turnsol, reddened by acids. It melts when exposed to a dull red heat. It is capable of attacking platinum, a property which is not possessed by the carbonate of potash or of soda. Several other salts of lithia have been examined, such as the borate, acetate, tartrate, &c. but these salts are not of sufficient importance to be described.* • Annales deChimie et de Physique, tome X. (Jan. 1819.) SALTS OF LIME 323 Chap.IV. SECTION V. SALTS OF LIME. Salts or Lime are combinations of the different acids Salts of with the salifiable base lime. The following are the most'"1* ; wh"£ - ° compounds. important of these compounds. I. Chlorate of Lime.—Former chemical name, Hyperoxy- Chiorateof muriate of Lime.—This salt may be obtained by the follow-l,me- ing process: Pass a current of chlorine gas through a solution of lime in hot water, the temperature of which is not allow- ed to fall. Two substances are in this way formed; namely, chloride of calcium and chlorate of lime. In order to get rid of the chloride, boil phosphate of silver in the solution of the chloride and chlorate. This salt decomposes the chlo- ride, and forms with it a chloride of silver and phosphate of lime, both of which are insoluble and may be separated by the filter; while the chlorate of lime remains in solution untouched, and may be obtained in crystals by evaporation. Chlorate of lime has a sharp and bitter taste, and is very deliquescent. When allowed to dissolve in the mouth, it produces a strong sensation of cold. When slightly heated, it undergoes the watery fusion. II. Hydrochlorate of Lime, it would seem, does not exist. Hydrochlo- The salt, which has heretofore been considered a hydro-|?teof,'me chlorate (muriate) of lime, does not differ, in any respect, exist. from chloride of calcium artificially formed. Hence there is good reason to believe, that, when the attempt is made to unite hydrochloric (muriatic) acid to lime, a double de- composition takes place, which results in the formation of chloride of calcium and water. III. Iodate of Lime.—This salt may be obtained by dis- solving carbonate of lime (chalk) in iodic acid; or by double decomposition between a salt of lime and iodate of potash. It is usually in the form of powder, but may be obtained in crystals. It is sparingly soluble in water. It is similarly affected by the action of heat to the iodate of potash, excepting that it requires a higher temperature for decomposition. IV. Hydriodate of Lime.—This salt may be formed by saturating hydriodic acid with carbonate of lime (chalk). It is a very soluble and deliquescent salt. When exposed to a strong heat, it is converted into iodide of calcium, water being at the same time formed. 324 SALTS. Book I. Division II Sulphate of lime occurs native. Its proper- ties. Anhydrous sulphate. Hydrosul- phate. V. SULPIUTK OF LIME. Syn Gypsum —Selenite.—Plaster of Pant. 1. Sulphate of lime occurs abundantly native in different parts of the world, and consequently is v.rv seldom formed artifici lly. It was known to the ancients under the name of gypsum, but its composiiion was not asc« rtained before it was subjected to analysis by Margraff and viacquer, who proved it to be a compound of sulphuric acid and lime. Its properties were afterwards investigated with precision by Bergman. 2. This salt is found native in the form of crystals, some- times exceedingly transparent. Its taste is slightly nauseous, but scarcely perceptible, unless in water impregnated with it. It is not altered by exposure to the air. When heated, it decrepitates and falls to powder, losing at the same time its water of crystallization, which amounts to about 21 per cent. In this state, it is called plaster of Paris, and is much employed in the formation of casts, and of some species of stucco, as well as for giving the last coat of plastering to the apartments of houses. It becomes well fitted for these pur- poses from the avidity with which it combines with, and solidifies, water, a property which enables it, when made into a paste with this liquid, to dry quickly and harden. When the sulphate is exposed to a violent heat, it melts. Before the blow-pipe, it affords an opaque vitreous globule. 3. Sulphate of lime is composed of Sulphuric acid 40—one atom. Lime 29—one atom. Giving 69 for the number represent- ing the weight of its atom. Besides the sulphate of lime, just described, which con- tains water, there has been found native an anhy drous sul- phate. It is in the form of transparent crystals, whose broad surfaces have the appearance of pearl. Its hardness is con- siderable. Its specific gravity is about 2*96. It usually phosphoresces when heated. It coincides with the common sulphate in properties, and in constituents, excepting that it contains no water. VI. Hydrosulphate qf Lime.—Usual chemical name, Hydrosulphuret of Lime.—This salt may be formed by passing a current of hydrosulphuric acid gas through water, suspending a portion of lime. When thus obtained, it is in the form of a colourless sqbation, possessing an acrid, bitter taste. SALTS OF LIME. 325 VII. Hydrosulphite of Lime—Usual chemical name, Chap iv. Hydroguretted Sulphuret of Lime.— This salt is formed, Hy(lr0SHl_' whenever sulphuret of lime is exposed to the air or mois-phite. Uned with water. The conversion takes place in consequence of the decomposition of water. It may be formed also by boiling a mixture of sulphur and lime in about ten times its weight of water. When thus prepared, it forms a solu- tion of a beautiful orange colour, exhaling the fetid odour of hydrosulphuric acid gas. Exposed to the air, it gradually absorbs oxvgen, which first combines with the hydrogen and afterwards acidifies the sulphur, whereby the hydro- sulphite is converted into a sulphate. When kept in close vessels, sulphur is deposited, and it becomes changed into a hydrosulphate. VIII. Nitrate qfLime.—Th\s salt may be formed by Nitrate. dissolving carbonate of lime (chalk) in nitric acid, evapo- rating the solution to the consistence of a syrup, and setting it aside to crystallize. It is in the form of crystals, which are exceedingly deliquescent, and possess an acrid and bitter taste. Cold water dissolves four times its weight of them, and boiling water, any quantity. When exposed to the air, it attracts moisture with such avidity as soon to li- quefv. It is this affinity for moisture, which fits it for the purpose of drying gases. When heated, it readily undergoes the aqueous fusion, and afterwards, when the water of crystallization is evaporated, it becomes converted into a white powder. When strongly heated, the nitric acid is decomposed, and deutoxide of azote (nitrous gas), oxygen and azote are evolved, while pure lime is left behind. IX. CARBONATE OF LIME. (Common name, Chalk.) 1. Carbonate of lime exists very abundantly native, Carhonate under the different names of chalk, lime-stone, marble, &c otllJ1^tbu and is, therefore, very seldom formed artificially by the dantiy na- chemist. It may be obtained, however, in a very puretivc- state, in the form of a precipitate, by adding a solution of carbonate of soda, to a solution of chloride of calcium (muriate of lime). When prepared in this way, it forms the precipitated chalk of the Dublin college. 2. For the purposes of medicine, it is prepared from the How pre- impure carbonate (chalk) by trituration in an iron mortar, p.ared for and subsequent levigation on a porphyry stone. The impal- poses of pable powder, thus formed, is next diffused in water, and,medicine- while this liquid continues to be loaded with the minute particles, it is poured off and allowed to settle. 3. Carbonate of lime is often found native in perfectly Properties. transparent crystals. It has scarcely any taste. It is inso- 326 SALTb Book I. luble in cold water. Its specific gravity is about 2*7. In Pivision IL the air, it suffers no alteration. When exposed to heat, it first decrepitates, and loses its water of crystallization, which amounts to about eleven per cent.; and afterwards, it the heat be continued to be raised, the carbonic acid is en- tirely driven off, nothing remaining but pure lime. Burning of 4. The process of exposing different carbonates of lime ,ime e*- (lime-stone) to a sufficient heat to drive off their acid is pame " called calcining or burning lime. It is in this way that all the lime is formed, which is used in the arts. It continued, for a long time, a problem of considerable difficulty to as- certain what lime-stone lost in the process for converting it into lime. It had been concluded by some of the earlier chemists that it was pure water. Stahl's opinion was most generally acceded to, that the change of properties was to be ascribed to the more minute division of the particles of the lime by the action of fire. On the other hand, Boyle supposed that the new properties depended upon the fixa- tion of fire, an opinion which was embraced by Newton. The chan- The fallacy of all these theories was completely shown by Se pS the discovery of carbonic acid by Dr. Black, in 1755. This in the pro- chemist satisfactorily proved that lime-stone was compos- c^'tedfor et* °^ *ime anc* carbonlc aci(^ ant* tnat» in the process of by Dr. calcining, the carbonic acid was driven off, while the pure Black. ijme remained behind. 5. Anhydrous carbonate of lime is composed of Carbonic acid 22—one atom. Lime 29—one atom. Giving 51 for the number represent- ing the weight of its atom. Medical 6. In medicine, carbonate of lime is an antacid and ab- bon8 °fofF"sorbent* II is therefore wel1 suited to remove acidity of Iime.te ' the stomach, more especially when accompanied with diar- rhoea. It removes acidity, in consequence of its acid being displaced by almost every other. For exhibition, it is gene- rally joined with sugar and aromatics, in the form of a mixture. Lime forms Phosphoric acid is capable of combining with lime in four Sthphos- proportions, forming phosphate, biphosphate, quadri- phorica'cid. phosphate and subphosphate of lime. These salts will be described in the order, in which they have been named. X. PHOSPHATE OF LIME. {Earth of Bones.—Burnt Hartshorn of the Colleges.) LPhos- 1. This salt may be prepared by exposing bones to a phate of wbite heatr reducing the substance formed to powder, dis- Srepared* solving it in hydrochloric (muriatic) acid, and precipitating SALTS OF LIME. 327 the solution by means of ammonia. The precipitate formed, Chap, iv. after being washed and dried, is pure phosphate of lime. 2. Bones are composed of a basis of phosphate of lime, united to a certain portion of cartilaginous matter. The ex- posure to a white heat burns off all the animal matters, and leaves nothing remaining but phosphate of lime. The phos- phate, however, is not pure. To render it perfectly so, the impure phosphate is treated with hydrochloric (muriatic) acid, which dissolves the pure salt alone. The ammonia, which is then added, combines with the hydrochloric acid and remains in solution, and causes the dissolved phosphate of lime to precipitate. 3. This salt was first noticed in 1774 by Scheele and Discovered Gahn; but for the first precise account of its properties, ^dSQChene chemistry is indebted to Ekeberg, Fourcroy and Vauquelin. 4. Phosphate of lime is a white insoluble powder, desti- Properties. tute of taste, and unaltered by exposure to air. It is solu- ble in hydrochloric (muriatic) and nitric acids, and may be precipitated from solution in them by means of ammonia. When exposed to a very violent heat, it undergoes a kind of fusion, and is converted into a white semi-transparent porcelain. 5. According to an analysis by Berzelius, calculated in numbers, in which the equivalent number for lime is as- sumed, phosphate of lime is composed of Phosphoric acid 34*3— Lime 29*0—-one atom; so that it appears that the composition of this salt cannot be recon- ciled with the atomic theory. 6. Phosphate of lime has been employed as a remedy in Employed rickets, a disease in which there appears to be a deficiency m lickets of this salt deposited in the bones. Its usefulness in this disease may be considered rather doubtful, unless the di- gestive powers of the system should be improved at the same time. XI. Biphosphate qf Lime.—This salt may be formed by 2. Biphfts digesting phosphate of lime in phosphoric acid, dissolved P1**1^ in hot water. The acid takes up so much of the phosphate as contains its own weight of phosphoric acid; hence this salt is a biphosphate. It does not crystallize; but, when evaporated to dryness, forms a white mass, somewhat deli- quescent in the air. It is soluble in water, but does not dis- solve in acids. Before the blow-pipe, it fuses into a trans- parent tasteless glass. XII. ^uadriphosphate of Lime.—Glassy Phosphoric Acids. Quadri- of the Apothecaries.—This salt may be formed by digest- phosphate ing, for some time, finely powdered phosphate of lime in a quantity of sulphuric acid, sufficient to saturate all the limr 328 SALTS. BookL of the phosphate, and afterwards diluting the mixture with vision u. a Sl,flicicnt quantity of water, and filtering. S ilph »te of lime remains on the filter, and a liquid quadriphosphate passes through. In this process, the sulphuric acid abstracts three- fourths of the lime contained in the phosphate, the corres- ponding portion of acid combining with the remaining un- decomposed phosphate. This salt, therefore, contains four times the proportional quantity of phosphoric acid that exists in the phosphate. When evaporated, it does not cry s- tallize, but forms soft crusts, which are soluble in water, and have an acid taste. When heated, it readily melts into a transparent tasteless glass, insoluble in water and acids, and not affecting vegetable blues. It is this salt from which phosphoric acid is made; hence the name given to it by the apothecaries. It is this salt also, from which phosphate of soda is formed by double decomposition with carbonate of soda. 4. Subphos- XIII. Subphosphate qf Lime.—This salt occurs native under the names of apatite or asparagus stone. Tungstate XIV. Tungstate of Lime.— Tungsten; Ponderous Stone.— 0 une' It was in this salt that tungstic acid was discovered by Scheele. It is somewhat transparent and of a yellowish grey colour. It is sometimes crystallized. It is insoluble in water, and not altered by exposure to heat. XV HYDROFLUATE OF LIME. [Usual chemical name, Fluate of Lime.—Common names, Fluor Spar—Der- byshire Spar. Hydroflu- 1. This salt exists abundantly native, and therefore need ate of lime. never De formed artificially by the chemist. In its pure state, free from silica, it is the salt from yvhich hydrofluoric (fluoric) acid is obtained by the action of sulphuric acid. Properties. 2. Hydrofluate of lime is found frequently crystallized. Its specific gravity is about 3*15. It is destitute of taste, and insoluble in water. It is not altered by exposure to air. When heated, it decrepitates and phosphoresces strongly in the dark. If it be kept hot for some time, it loses the phosphorescent property, which cannot be restored, unless its constituents are separated and then recombined. When exposed to a very intense heat, it melts into a transparent glass. 3. According to an analysis by Sir H. Davy, given in numbers, in which the acid is calculated proportionally from the equivalent number for lime, this salt is com- posed of Hydrofluoric acid 10-Q— Lime 29-0—one atom. SALTS OF LIME. 329 Supposing the foregoing numbers correct, and that this Chap.IV. salt is a compound of a single atom of each of its proxi- ~ mate constituents, then the equivalent number for hydro- fluoric acid would be 10*9. XVI. Silicofiuate of Lime—This salt occurs very abun- g,|jjj,*lf dantiy native, and cannot be distinguished by the eye from the hydrofluate (fluate). When distilled with sulphuric acid, it yields silicofluoric acid. The difference between this salt and the last described should be attended to; as it is only from fluor spar, perfectly free from silica, that the hydro- fluoric (fluoric) acid can be obtained. XVU. Sulphocyanate of Lime—This is a deliquescent salt, which may be obtained crystallized in needles. XVIII. Ferrocyanate of Lime.—This salt may be formed by pouring fifty-six parts of lime-water upon two parts of perferrocyanate of iron (Prussian blue), and boiling the mixture, until it no longer alters paper stained with tur- meric. It must then be filtered. The liquid, thus obtained, is a solution of this salt. It has a greenish yellow colour and an unpleasant bitterish taste. When evaporated, it yields small crystalline grains. XIX. Oxalate qf Lime.—This salt may be formed by Oxalate. dropping oxalic acid into a solution of any salt of lime. It immediately precipitates in the form of a white powder, which is destitute of taste. The readiness with which oxalic acid forms this salt, when it comes in contact with lime, makes it a very useful test for the presence of the latter substance. XX. Tartrate qf Lime.—This salt may be formed by Tartrate of adding carbonate of lime (chalk) in powder to a solution,,,uae in boiling water, of bitartrate of potash (cream of tartar), as long as any effervescence ensues. The carbonate is de- composed; its acid is evolved and causes the effervescence, while its base combines with the excess of acid in the bitartrate, and falls down in the form of an insoluble tar- trate of lime. This salt is a tasteless white poyvder, nearly insoluble in cold water. It is rendered soluble, however, by being mixed with tartrate of potash (soluble tartar) or tartrate of potash-and-soda (Rochelle salt). XXI. Tartrate of Potash-and-Lime may be formed by Tartrate of adding lime-water to a solution of tartrate of potash, until potash-and- a precipitate begins to appear, and allowing the mixture to lr cleposite crystals by spontaneous evaporation. XXII. Benzoate of Lime may be worth mentioning, in Benzoate order to insert the curious fact that it has been found abun- of Lime* dandy in the urine of cows. It is in the form of white, 2T 330 SALTS. Book I. shining, pointed crystals ot a sweetish taste, which arc Division H. mucl) mort soluble in hot than in cold water. XXIIL Moroxylate of Lime.—This is the salt, found crystallized on the bark of the mulberry tree, and from which the moroxy lie acid, already described, is obtained. Kmateof XXIV. Kinate of Lime has already been noticed as the umej sajt 0f Deschamps, from which Vauquelin first obtained the kinic acid. It may be prepared by macerating yellow Peru- vian bark in yvater, concentrating the liquid formed, and setting it aside for spontaneous evaporation. It is in the form of white crystals, destitute of taste, and having some flexibility under the teeth. It dissolves in about five times used in me-its weight of cold water. It has been used in medicine as dicine. a SUDStitute for the pcrUvian bark, tnd it is said to possess all the virtues of this valuable medicine. List of salu Besides the salts of lime here mentioned, there have been described01 described, more or less accurately by chemists, the sul- phite, hyposulphite, selenate, hydroselenate, tellurate, bo- rate, hypophosphite, arseniate, arsenite, chromate, molyb- date, antimonite, urate, gallate, purpurate, sorbate, succinate, acetate, saclactate, citrate, mellate, camphorate, malate, lactate, suberate, zumate, and boletate; but these salts are not of sufficient importance to be described. The remain- ing salts of lime, amounting in number to 16, are un- known. General The salts of lime may be recognised by the following ofthe'saits general properties or marks. of lime. 1. A large proportion of them are insoluble, and those which are soluble cannot be crystallized. 2. The insoluble salts, by being boiled in a solution of carbonate of potash, y ield a white powder, which is soluble with effervescence in nitric acid, and has all the characters of carbonate of lime (chalk). 3. The soluble salts, upon the addition of potash or soda, let fall a white powder, which has all the properties of pure lime. 4. When oxalate of ammonia is dropped into a salt of lime, a dense white precipitate immediately appears, con- sisting of oxalate of lime. SALTS OF BARYTES. 331 Chap. IV, SECTION VI. SALTS OF BARYTES. Salts of Barytes are combinations of the salifiable base Saitsofba* barytes with the different acids. The most important of ry^sj'o^nhdast these salts are the following. I. Chlorate of Barytes.—Former chemical name, Hy- Chlorate of per oxymuriate of Barytes.—This salt may be obtained barJte8- and purified by an analogous process to that given for form- ing chlorate of lime, to which salt the reader is referred. It has a sharp austere taste, and is soluble in about four times its weight of cold yvater. When heated, it loses 39 per cent, in oxygen gas. II. Hydrochlorate qf Barytes does not exist. This is Hydrochlo- made evident from the circumstance, that chloride of bari- rate l^?es urn, artificially formed, does not differ from the compound, which is generally considered a muriate (hydrochlorate) of barytes. Hence the presumption is that hydrochloric (muriatic) acid and barytes never come in contact without mutual decomposition. III. Iodate qf Barytes.—This salt may be obt lined by dissolving carbonate of barytts in iodic acid. It precipitates in a powder, which, after being dried, resembles flour. When heated sufficiently, it is decomposed into oxygen, iodine and barytes. IV. Hydriodate of Barytes.—This salt is in the form of crystals, very soluble in water and slightly deliquescent. When exposed to the air, it is partially decomposed; a por- tion of its acid is dissipated, and carbonate of barytes, formed. In close vessels, it may be heated to redness yvith- out undergoing alteration; but at the same heat in the open air, it is converted into iodide of barium. V. Sulphate of Barytes.—Formerly called, Ponderous Sulphate of Spar.—This salt is found abundantly in difft-rent parts of Darytea- the world. Its composition yvas first ascertained by Gahn. It is found native crystallized, but has never been obtained in crystals by art. It is insoluble in water, and in sulphuric acid unless concentrated and boiling. When suddenly heated, it breaks to pieces and flies about with a crackling noise, owing to the conversion of the water yvhich it contains into vapour. Before the blow-pipe, it melts into a white opaque globule. When formed into a thin cake with flour and yvater, and heated to redness, it acquires the property *f phosphorescing in the dark. There is a variety of this 332 SALTS. Book l salt found native, called Bologna stone, which has this pro- nivi8ion11- perty naturally. It is composed of Sulphuric acid 40—one atom. Barytes 78— 118 Supposing this salt to be a compound of a single atom of each of its ingredients, then the number representing an atom of barytes yvould be 78, and that for the salt, 118. Hydrosul- VI. Hydrosulphate of Barytes.—Usual chemical name, phate. Hydrosulphuret of Barytes.—This salt may be obtained by pouring boiling water over sulphuret of barytes. As the solu- tion obtained cools, a number of crystals form, which consist of the salt in question. In this process, by the decomposi- tion of water, a large quantity of hydrosulphuric acid gas (sulphuretted hydrogen) becomes formed; part of which combines with the barytes and is deposited in crystals. The remainder, before it combines with the barytes, unites with an excess of sulphur, and then forms, with this alkaline base, a hydrosulphite (hydroguretted sulphuret), which re- mains in solution. Hydrosulphate of barytes is in the form of white crystals, possessing a silky lustre. Its solution in water has a slight green tinge, and an acrid and sulphureous taste. When exposed to the air, it is readily decomposed. Hydrosul- VII. Hydrosulphite of Barytes.—Usual chemical name, phite. Hydroguretted Sulphuret of Barytes.—This salt remains in solution, after the crystals of hydrosulphate of barytes have deposited from the liquid, formed by treating sulphuret of barytes with boiling water. It has a green colour and an acrid taste. Nitrate of VIII. Nitrate qf Barytes.—This salt may be obtained barytes. by dissolving native carbonate of barytes (witherite) in nitric acid, and evaporating the solution, until crystals form. It has a hot, acrid and austere taste. It is soluble in twelve parts of cold water, and in three or four parts of boil- ing water. Its specific gravity is 2*9. It undergoes very little change in the air. When exposed to heat on coals, it decrepitates, undergoes a kind of fusion, and afterwards becomes dry. In a very strong heat, its acid is dissipated, and pure barytes remains behind. It is composed of Nitric acid 54—one atom. Barytes 78— 132 On the supposition that this salt contains one atom of baryt s only, it is perceived, that, from its composition, the seme equivalent number is deduced for the atom of barytes, as from the composition of the sulphate. SALTS OF BARYTES. 333 IX. Carbonate of Barytes.—Witherite of Mineralogists.— Chap. IV. This salt may be prepared, artificially, by exposing barytes Carbonate Water to the open air, or by submitting it to the action of a of barytes. stream of carbonic acid gas. It was first examined by Berg- man; but Dr. Withering discovered it native, and hence its name of witherite. It exists native in crystals. It has no sensible taste. The specific gravity of native specimens is 4*3, while that of the salt, artificially formed, scarcely ex- ceeds 3'7. It is but sparingly soluble in water, and not altered by exposure to the air. In a very violent heat along with charcoal, it is decomposed. It is not employed in me- dicine, but is used in the preparation of the chloride of barium, which is officinal. It is composed of Carbonic acid 22—one atom. Barytes 78— 100 The above numbers scarcely differ from those of the most careful analyses, heretofore made of this salt. This, there- fore, is an additional evidence that 78 is the real equivalent number for barytes. X. Hydrofluate of Barytes.—Usual chemical name, Flu- Hydi-oftu- ate of Barytes.—When hydrofluoric (fluoric) acid is drop- jj1*^ ba" ped into barytes water, this salt is precipitated in white flocks, which are tasteless, and insoluble in water. XI. Silicqfluate of Barytes.—Usual chemical name, Sili- cated Fluate of Barytes.—When nitrate of barytes is poured into silicofluoric (fluosilicic) acid, after an interval of some minutes, this salt precipitates in the form of small hard crystals, yvhich are insoluble in yvater, and in nitric and hy- drochloric (muriatic) acids. XII. Sulphocyanate qf Barytes is a deliquescent salt in the form of crystals of a brilliant yvhite colour. XIII. Ferrocyanate of Barytes.—This salt may be form- Fen-owa- ed by adding perferrocyanate of iron (Prussian blue) to hotnate °^ba" barytes water, until the former ceases to be discoloured. The liquid thus obtained, after being filtered and gently evapofated, yields crystals consisting of this salt. It has a yellow colour, and is sparingly soluble in water. When ex- posed to a red heat, it is decomposed, and its acid destroy- ed. According to an analysis by Porrett, it is composed of Ferrocyanic acid 68*2— Barytes 78-0— Assuming 78 for the equivalent number for barytes, it is perceived that the proportion, in which the proximate con- stituents of this salt combine, goes to confirm the chemical constitution, assigned by Porrett to the ferrocyanic acid. 334 SALTS. Book l XIV. Acetate qf Barytes.-—When barytes or its carbo- DivisionII. nattr 19 dissolved in acetic acid, or when the sulphuret of Aeetate. barytes is decomposed by the same acid, the liquid forned deposites this salt, by spontaneous evaporation, in transpa- rent needle-form crystals. It has an acrid and somewhat bitter taste, and effloresces in the air. It is decomposed by almost all the sulphates; its base precipitating in combina- tion yvith sulphuric acid. From this circumstance, it is often employed to detect sulphuric acid in solutions. List of the Of the remaining salts of barytes, there have been more rytes°nota or *css described by chemists, the sulphite, s. lenate, hydro- described, selenate, tellurate, borate, phosphate, phosphite, hy pophos- phite, arseniate, arsenite, chromate, tungstate, antimoniate, antimonite, urate, purpurate, formate, oxalate, sorbate, suc- cinate, tartrate, benzoate, saclactate, citrate, mellate, cam- phorate, malate, lactate, suberate, zumate, and boletate; but these salts are of too little importance to be described. The rest of the salts of barytes, amounting in number to 18, are unknoyvn. Chemical Several of the salts of barytes are of considerable im- saTu oVba- Portance to tne chemist. It was by taking advantage of the rytes. insolubility of the sulphate, that Porrett was enabled to in- sulate the ferrocyanic acid, and Gay-Lussac, to obtain chloric acid in a separate state. The processes, by which these acids are obtained, have been already described. They are All the salts of barytes are poisonous, unless the sulphate poisonous. .g an exception. The innocence of this salt is to be attribu- ted to its great insolubility. What was formerly considered to be a muriate (hydrochlorate) of barytes, but now found a chloride of barium, has been used in medicine; but its utility, as a remedy, is rather equivocal. The medical pro- perties attributed to it have been noticed under the head of chloride of barium. The consti- By the analyses, which have been selected in the present barytes section, the reader has no doubt observed, that 78 repre- may be cal- sents the atom, or, if the term be preferred, the combining from^er- We*ght OI" barytes. This alkaline base has not been analyzed tain data, with precision, but notwithstanding the proportion in which its constituents combine may be made evident by data fur- nished in the analysis of chloride of barium, given at page 61. By this analysis, it is perceived, that the number repre- senting the atom, or combining weight, of barium is 70. Now if it be supposed, agreeably to the analogy of the other alkaline salifiable bases, that barytes contains one atom only of oxygen, then the weight of its compound SALTS OF STRONTIAN. 335 atom would be 70-f 8«s=78, the same number, which is ob- Chap.IV. tained by the analysis of the salts of barytes. This coinci- dcnce makes it almost certain, without recourse to analysis, that barytes is composed of 70 barium+8 oxygen. The salts of barytes may be known by the following General general properties or marks. AXlXi 1. A large proportion ot them are insoluble in water, 0fbarytes. even larger than of the salts of lime. 2. When a small quantity of sulphate of soda (Glauber's salt) is dropped into them, there is formed a white precipi- tate, which is insoluble in sulphuric acid, and has the pro- pi rties of sulphate of barytes. 3. When heat is applied to them, they remain unaltered, unless they should contain a combustible or volatile acid. In the first case, the acid is driven off; in the second, it is converted into carbonic acid, which combines yvith the barvtes. SECTION VII. SALTS OF STRONTIAN. Salts of Strontian are combinations of strontian with Salts of the different acids. The following are the most important st[ontian» r , , ° r what com- oi these salts. pounds. I. Chlorate qf Strontian.—Former chemical name, Hy- Chlorate of peroxymuriate of Strontian.—This salt may be obtained8trontian- and purified by a similar process to that given for obtaining chlorate of lime. It is in the form of deliquescent crystals. On burning coals, it undergoes fusion and emits a purple flame. II. Hydrochlorate of Strontian does not exist. When Hvdrochio- hydrochloric acid and strontian are allowed to act on each rate does othes, a double decomposition takes place, and water and not exi8t' chloride of strontium are formed. III. Iodate of Strontian.—This salt may be obtained by dissolving carbonate of strontian in iodic acid. It is in the form of small crystals which are soluble in water. IV. Hydriodate of Strontian.—This salt is very soluble in water. It melts, when exposed to a heat rather below redness. Its fusion produces but little alteration in close vessels, but, in the open air, causes a partial decomposition, vapours of iodine being emitted. V. Sulphate qf Strontian—This salt may be formed Sulphate. 336 salt.v Book I. artificially by dropping sulphuric acid into strontian water. DivisionH. jt occurs abundantly native, usually in the form of crystals, in different parts of the yvorld. I is destitute of taste, and scarcely soluble in water. Sulphuric acid dissolves it r. a- dily by the assistance of heat; but it is separated again by the addition of water. It is composed of Sulphuric acid 40—one atom. Strontian 52— 92 The numbers, above given, scarcely differ from the most accurate analyses, hitherto made of this salt. Supposing one atom only of strontian in its composition, then the number representing the atom of strontian would be 52. Nitrate. VI. Nitrate qf Strontian.—This salt may be formed, either by dissolving carbonate of strontian in nitric acid, or decomposing the sulphuret of strontian by means of the same acid. In either case, the liquid obtained is evaporated to dryness, re-dissolved in water, and then evaporated slow- ly, until crystals form. This salt has a strong, pungent, cooling taste. Its crystals are perfectly transparent, and possess a great deal of lustre. Its specific gravity is 3'0u6. It is soluble in its own weight of cold water, and in a little more than half its weight of boiling water. In the air, it undergoes no change. It deflagrates on hot coals; and, in a crucible exposed to heat, it first decrepitates gently, and then melts. At a red heat, it boils and its acid is dissipated. If a combustible be brought in contact with it at this time, it deflagrates with a vivid red flame. When one of its crystals is put into the wick of a burning candle, it com- municates a purple colour to its flame. It is composed of Nitric acid 54—one atom. Strontian 52— 106 The numbers, above given, scarcely differ from those of the best analyses, heretofore made of this salt and it is per- ceived that the equivalent number for strontian turns out to be the same as when deduced from the sulphate. Carbonate. VII. Carbonate qf Strontian.—-This salt has been found native at Strontian and Leadhills, in Scotland. It yvas first distinguished from carbonate of barytes, in 1798, by Craw- ford. It is usually found in striated, semi-transparent masses of a greenish tinge. Its specific gravity is about 3*66. It has no taste, and is nearly insoluble in yvater. It is not al- tered by exposure to air. When made into a paste with SALTS OF STRONTIAN. 337 charcoal and strongly heated, it is entirely decomposed. It Chap. IV. is composed of Carbonic acid 22—one atom. Strontian 51— 74 As the same quantity of strontian combines with an atom of carbonic acid, as with an atom of sulphuric or nitric acid, the equivalent number for an atom of this base may be safely taken at 52; and 74 m.iy be considered as the number representing the weight of an atom of carbonate of strontian. VIII. Hydrofiuate of Strontian.—Usual chemical name, Hydron* Fluate of Strontian.—When hydrofluoric (fluoric) acid is ate. dropped into strontian water, this salt precipitates in the form of a white powder, insoluble in water, but soluble in hydrofluoric (fluoric), nitric, and hydrochloric (muriatic) acids. IX. Ferrocyanate of Strontian.—Usuai chemical names, FerrooyaV Triple Prussiate of Strontian; Prussiate of Strontian-and- nate- Iron.—This salt may be formed by adding perferrocyanate of iron (Prussian blue) to hot strontian water, as long as the former becomes discoloured, and evaporating gently the liquid obtained, until it deposites crystals. It does not crystallize nearly so readily as the ferrocyanate of barytes. When evaporated to dryness, it does not deliquesce. It is soluble in less than four times its weight of cold water. Of the remaining salts of strontian, the following have List of salts been more or less ^examined by chemists; namely, the hy- ^j"^.^ posulphite, hydrosulphate, hydrosulphite, selenate, hydro-ed. selenate, borate, phosphate, hypophosphite, arseniate, arse- nite, chromate, sulphocyanate, urate, purpurate, oxalate, succinate, acetate, tartrate, citrate and zumate; but these salts are of too little importance to be described. The rest •f the salts of strontian, amounting to 34, are unknown. From the analyses, which have been given of the salts of The com- strontian, it appears that the atom or combining weight of P^j"of strontian is represented by 52. By the composition of the may be cat- chloride of strontium, it appears that the atom of strontium culated- is represented by 44. Now, if it be supposed that strontian contains one atom of oxygen, then its composition will be 44 strontium + 8 oxygen = 52. This composition agreeing precisely with the equivalent number for strontian, deduced from its salts, its correctness may be considered as almost certain. The salts of strontian may be distinguished by the fol- General lowing properties or marks. propertUSs 2Uf 338 SALTS. Boor I. 1. They are in general more soluble than the salts of Divi,iopl1- barytes, but less so than the salts of lime. of thi- salts u. Their solutions in water are precipitated by the sul- o strontian. phates> phosphates, and oxalates. 3. They are distinguished from the salts of barytes, very readily, by means ot oxalate of ammonia. This salt, when dropped into the salts of strontian, produces no precipitate; but when added to the salts of barytes, a precipitate imme- diately appears. 4. A piece of paper, dipped in a salt of strontian and set on fire, burns with a red flame; but after being dipped into a salt of barytes, it burns with a yellow flame. 5. The salts of strontian are not poisonous, as is the case with the salts of barytes. SECTION VIII. SALTS OF MAGNESIA. Salts of Salts of Magnesia are combinations of magnesia with wh^co*'- the different acius. The following are the most important pounds. of these salts. Chlorate of L Chlorate of Magnesia.—Former chemical name, Hy- magnesia. peroxymuriate of Magnesia —This salt may be prepared and purified in the same manner as the chlorate of lime, which it resembles very much in properties. Hydrochlo- II. Hydrochlorate of Magnesia does not exist. What rate does jja(j Deen previously considered a muriate (hydrochlorate) of magnesia does not differ from chloride of magnesium, artificially formed. Hence there is reason to believe that hydrochloric (muriatic) acid and magnesia never act upon each other without mutual decomposition. III. Hydriodate of Magnesia.—This is a deliquescent, difficultly crvstallizable salt, which is decomposed when heated to redness, its acid being driven off. IV. SULPHATE OF MAGNES1 V. (Common names, Vitriolated Magnesia—Epsom Salt.) Sulphate of 1. This salt is obtained, in great abundance, by evapora- magnesia; tion, from the bittern, left after the extraction of chloride of tion?an* sodium (common salt) from sea water. It exists plentifully in the springs at Epsom in England, from which it is ob- tained in considerable quantity, mixed with a portion of sulphate of soda (Glauber's salt). 2. It is obtained in Italy from certain minerals contain- SALTS OF MAGNESIA. 33$ ing sulphur and magnesia. These minerals are first roasted, Chap. IV. and afterwards moistened with water and exposed to the- air. By this treatment, the sulphur becomes acidified, and the sulphate of magnesia effloresces on their surface. The salt is afterwards purified by solution in water, by treatment with lime to precipitate any metallic substance, and by re- ptated crystallizations. 3. Sulphate of magnesia has an intensely bitter taste. Its Proper- specific gravity is 1*66. It dissolvts in its own weight of*"*8, cold water, and in rather less than two-thirds of its weight of boiling water. When exposed to the air, it effloresces and is reduced to powder. Its deliquescence is owing to the presence of chloride of magnesium (muriate of magnesia.) When exposed to heat, it undergoes the watery fusion, and afterwards, if the temperature be increased, its water, which amounts to about half its weight, is driven off, and the salt becomes dry; but it is not decomposed, hoyvever high the temperature may be raised. Before the blow-pipe, it melts with difficulty into a vitreous globule. It is composed of Composi- Sulphuric acid 40—one atom. tion- Magnesia 20—• 60 Supposing this salt to contain but one atom of its base, then the equivalent number for magnesia would be 20. 4. In medicine, sulphate of magnesia is a mild and gentle Medical purgative, operating, in general, without occasioning grip- ProPert'«8- ing or sickness of stomach. It may be so managed, however, as to promote evacuation through other channels. If the patient be kept warm after its exhibition, it promotes per- spiration; and, if he take exercise in the cool air, it pro- duces discharges through the kidneys. Its dose is from six drachms to one ounce. V. Nitrate of Magnesia.—This salt may be prepared by Nitrate of saturating nitric acid with magnesia, and evaporating the magnesia. solution thus obtained to a proper consistency. It precipi- tates in the form of crystals, which have a bitter and dis- agreeable taste. It dissolves in a little more than its weight of cold water, and in a smaller proportion of boiling water. In the air, it is deliquescent. When exposed to heat, it undergoes the watery fusion, and, if the heat be continued, loses its water of crystallization, amounting to about thirty per cent, and is converted into a drv powder. In a strong heat, its acid is decomposed and driven off, while its base remains behind in a state of purity. It is composed of Nitric acid 54—one atom. Magnesia 20— 74 340 SALTS. Book I. If this salt contain but one atom of its base, then the Division H. tgujvalent number for magnesia will be twenty, exactly the same number which is deduced from the composition of the sulphate. Magnesia Carbonic acid combines in two proportions with magnesia, ■aits w!tb° anc* *onn8 carbonate and bicarbonate of magnesia. °*r,bonic VI CAKBONATE OF MAGNESIA. acid. (Commonly called, White Magnesia.) 1. Carbo- nati of magnesia; how obtain ed. How oh. tained in the large way. Another method. Froperties. l.This salt may be obtained by mixing together, solu- tions of equal parts of sulphate of magnesia (Epsom salt) . and carbonate of potash (salt of tartar), and boiling them for some time; a white precipitate is formed, which con- sists of carbonate of magnesia. It must be washed repeat- edly wuh water, until this liquid comes off tasteless. 2. The explanation of the above process is this: By the mutual action of the salts employed, a double decomposi- tion takes place, and there is formed sulphate of potash (vi- triolated tartar) and bicarbonate of magntsia. Both these salts remain in solution at first; but, by the subsequent boil- ing, some carbonic acid is driven off, whereby the bicarbo- nate is converti d into a carbonate, which, being insoluble, immediately forms a precipitate. It requires to be washed, in order to dissolve ayvay any sulphate of potash, with which it may be mixed. 3. Carbonate of magnesia, in the large way, is generally obtained from bittern, or the liquor which is left after the crystallization of chloride of sodium (common salt), in salt works. This liquor contains chloride of magnesium (mu- riate of magnesia) and sulphate of magnesia. 4. It may be obtained also in the process for forming sul- phate of ammonia, for the purpose of forming afterwards hydrochlorate of ammonia (sal ammoniac) by double decom- position with chloride of sodium (lommon salt). This sul- phate is prepared by double decomposition, from sulphate of magnesia (Epsom salt) and carbonate of ammonia (mild volatile alkali); and there is obtained, at the same time, a carbonate of magnesia. By this process, it was manufactur- ed bv Dr. Campbell in England. 5. This salt exists abundantly native, in the magnesian lime-stone of England. It has been for a long time known, but its composition was first ascertained by Dr. Black. 6. Carbonate of magnesia is a very light, yvhite, opaque substance, destitute of taste or smell. It is soluble in about 480 times its weight of water, SALTS OF MAGNESIA. 341 7. It is composed of Chap. IV. Carbonic acid 22—one atom. Magnesia 18— 40 This analysis gives 18 for the equivalent number of mag- nesia. This number does not agree very well yvith that de- duced from the composition of the sulphate and nitrate. 8. As a medicine, the properties of carbonate of magnesia Medical art those of a purgative and corrector of acidity. Its purga- P,>0Perties- ti»e property, however, is not very manifest, unless it meet with an acid in the stomach; in which case, it is decomposed, and i's base, combining with such acid, forms a new com- pound, which often proves purgative. When such a decom- position takes place, the extrication of carbonic acid will sometimes create a troublesome flatulence. VII. BICARBONATE OF MAGNESIA. 1. This salt mav be obtained by mixing together, in so-2 Bicarbe- lution, 123 parts of sulphate of magnesia (Epsom salt) and naJ*.5 ho.w 136 parts of carbonate of soda, and filtering the liquid formed. In a few days, the bicarbonate falls doyvn in crys- tals. It may be formed also by passing carbonic acid into water, in which carbonate of magnesia has been diffused. The carbonate is thereby converted into a bicarbonate, and dissolves in the water. 2. This salt has little taste. It is soluble in about 48 parts Properties. of cold water when in crystals; but in powder, it requires at least ten times as much for solution. When exposed to the air, it effloresces and falls into powder. It contains about 25 per cent, of water. When heated, it decrepitates, becomes converted into a powder and is decomposed. 3. It is composed of Carbonic acid 44—two atoms. Magnesia 22— 66 Bv this analysis, 22 turns out to be the equivalent number for magnesia, which differs from that deduced from the composition of the sulphate and nitrate. These two salts give it at 20. There is reason, hoyvever, to consider 20 as the correct number, since the mean of the numbers, afford- ed in the analysis of the two carbonates, is exactly 20. 4. There can be very little doubt that the bicarbonate of a good sub- magnesia would prove a very excellent substitute for the stitute ft* common carbonate as a medicine. The additional quantity ntteTs^ of carbonic acid, yvhich it contains, could not fail to make medicine. 342 SALTS. Book i. it better suited to some cases, in yvhich the common carbo- Division n n tf(j Js use(^ an(j jts 8u|ubility, in this state of preparation, would render it much Itss disagreeable to be swallowed. There is very little question that the different preparations of magnesia in the liquid form, sold in thv United States, are nothing else but solutions of bicarbonate of magnesia. Phosphate VIII. Phosphate of Magnesia.—When the solutions of ojuagne- phosphate of soda and sulphate ol magnesia (Epsom salt) are mixed together, no appartnt change takes place at first. In a few hours, however, this salt forms in large transpa- rent crystals, possessing very little taste, but leaving a cooling and sweetish impression on the tongue. It is solu- ble in about 15 parts of cold water, and in a smaller quan- tity of boiling water. In the open air, it loses its water of cr stallization and falls to powder. It has been detected in the bones of all animals, except those of man. Hydro- IX. Hydrofluate qf Magnesia.—Usual chemical name, Fluate of Magnesia.—This salt may be formed by dissolv- ing carbonate of magnesia in hydrofluoric (fluoric) acid. When thus obtained, it is a tasteless yvhite powder, insolur ble in water, and scarcely soluble in acids. When formed, by double decomposition, from hydrofluate (fluate) of pot- ash and sulphate of magnesia, it is at first in the form of a gelatinous mass, soluble in acids; but after it has become dry, it is insoluble. X. Tartrate of Magnesia.—This salt is insoluble, unless it contains an excess of acid, in which case it may be ob- tained by evaporation in small crystals. Tartrate of XI. Tartrate qf Potash-and-Magnesia.—This salt may pot«sii-and-be formed by dissolving magnesia, or its carbonate, in magnesia, bitartrate of potash (tartar). The extra atom of tartaric acid, in the bitartrate, becomes saturated with magnesia, and thus the triple salt is formed. Its properties have not been investigated. Its constituents render it deserving of a care- ful examination by physicians, with a view to its medicinal powers. List of the Besides the salts of magnesia just described, there m'-^ne'sia ^ave been more or ^ess examined by chemists, the am- notdescrib- monio-sulphate, potasso-sulphate, soda-sulphate, sulphite, ed- ammonio-sulphite, hydrosulphate, hydrosulphite, selenate, hydroselenate, ammonio-nitrate, borate, ammonio-phos- phate, arseniate, chromate, molybdate, tungstate, sulphocy- anate, ferrocyanate, urate, purpurate, gallate, oxalate, sor- bate, succinate, acetate, benzoate, saclactate, citrate, cam- phorate, malate, lactate, ammonio-lactate, suberate, and SALTS OF YTTRIA. 343 zumate. The rest of the salts of magnesia, amounting in Chap. iv. number to 27, an unknown. Assuming 20 as the true number representing the atom Constitu- or combining weip-ht of magnesia, yvhat composition can be entsof. ■ i • i l • v . c • c • magnesia, reasonably assigned to this substance, in confirmation ot its deduced correctness? In answer to this question, it may be saiu, theoreti- that the atom of magnesium, as deduced from its chloride,ca y turns out to be 12. Now if it be supposed, that magnesia is a compound of one atom of magnesium and one atom of oxygen, its equivalent number will be 12+8=20, the same number as given by the salts of magnesia. This, therefore, may be considered the true composition of magnesia. The salts of magnesia may be known by the following General general properties or marks. properties 1. A large proportion of them are soluble in water and 0f magne- capable of crystallization. sia. 2. They let fall a white flocky precipitate, when potash or soda, or the carbonates of these alkaline bases, are drop- ped into their solutions. When the pure bases are used, the precipitate is pure magnesia; but when the carbonates are employed, the precipitate is carbonate of magnesia. 3. If phosphate of soda be dropped into a salt of mag- nesia, no apparent change takes place; but afterwards, if ammonia be added, a triple salt, composed of phosphoric acid, ammonia and magnesia, will fall in the form of a white precipitate. SECTION IX. SALTS OF YTTRIA. Salts or Yttria are combinations of the earthy salifiable Salts of base y ttria with the different acids. Five only of these ytlria: compounds will be described. jjjjj con>- puuuus. I. Hydrochlorate of Tttria—Former chemical name, Hydrochlo Muriate of Tttria—This salt does not crystallize, but at-^ofyt- tracts moisture very rapidly from the atmosphere and runs tria' into a jelly. When exposed to a gentle heat, it dries with difficultv, and afterwards melts. II. Sulphate of Tttria.—When yttria is dissolved in sul-Sulphate phunc acid, this salt crystallizes in small brilliant white grains. Its taste is sweet and astringent, and its colour, light- red. It is not altered by exposure to air. Its specific gra- vity is 2-791. It is soluble in about 30 parts of cold water. When exposed to a red heat, it suffers decomposition. 344 SALTS. BookL III. Nitrate of Tttria.— This salt may be obtained by Duision II. dissolving yttria in nunc acid. The solution has a sweet Nitrate. astringtnt taste. It can hardly be obtained in crystals. When exposed to the air, it attracts moisture and deli- quesces. IV. Carbonate of Tttria.—This salt may be obtained by precipitating any acid solution of yttria by means of car- bonate of potash or of soda. It is a white, tasteless, insolu- ble powder. V. Hydrofluate of Tttria.—Usual chemical name, Fluate qf Tttria.—This salt may be formed by decomposing hy- drofluate (fluate) of potash by means of hydrochlorate (muriate) of ytti ia. It is a white, tasteless poyvder, totally insoluble in water. List of the Of the remaining salts of yttria, there have been more t*',U ^d" or less examined by chemists, the hydrosulphate, selenate, scribed. phosphate, arsenite, chromate, oxalate, succinate, acetate and tartrate; but these are not of sufficient importance to be described. The rest of the salts of yttria, amounting in number to 49, are unknown. General The salts of yttria may be known by the folloyving pro- P*°rrti|S perties or marks. •f yttria! *• They are precipitated by phosphate of soda, carbonate of soda, oxalate of ammonia, and tartrate of potash (soluble tartar). 2. They bear considerable resemblance to the salts of lime, in the degree of their solubility; but they may be distinguished from these salts, by being converted into a sulphate, which is soluble and has a sweet taste, very dif- ferent from the sulphate of lime. SECTION X. SALTS OF GLUCINA. Salts of rIu- Salts of Glucina are combinations of plucina with the cina; what different acids. Five only of these compounds will be compounds. describcd. Sulphate of I* Sulphate of Glucina.—When glucina is dissolved to glucina. saturation in sulphuric acid, and the solution evaporated, this salt forms in needle-shaped crystals. It has a very s-veet and somewhat astringent taste. It is soluble in water. By heat, it undergoes the watery fusion, and afterwards its SALTS OF GLUCINA. 345 water is dissipated, and it is converted wito a powder. At a Chap. IV. red heat, its acid is driven off, and nothing remains but pure glucina. II. Nitrate of Glucina.—This salt may be formed by Nitrate. saturating nitric acid with glucina. It cannot be obtained in crystals. When its solution is evaporated, it gradually assumes the form of a white powder. It has a sweet and astringent taste, and is very soluble in water. When ex- posed to the air, it attracts moisture very rapidly. When heated, it readily melts; and if the temperature be increas- ed, its acid is dissipated, while the pure earthy base remains behind. III. Carbonate of Glucina.—This salt mav be obtained Carbonate. by precipitating an acid solution of glucina, by means ot the carbonate of potash or of soda. It is in the form of a soft, white, and exceedingly light powder, which has a greasy feel. It is destitute of taste, and insoluble in water. It is not altered by exposure to the air. It is easily decomposed when submitted to the influence of heat, its acid being driven off. IV. Phosphate of Glucina—When phosphate of soda is Phosphate. added to a solution of glucina in sulphuric, nitric or hy- drochloric (muriatic) acid, this salt precipitates in the form of a tasteless white powder, which is insoluble, unless it contains an excess of acid. It is incapable of crystallizing, and is not altered by exposure to the air. V. Hydrofluate of Glucina.—Usual chemical name, Fluate Hydro- of Glucina.—This salt may be formed by dropping hydro-fluate' fluate (fluate) of potash into hydrochlorate (muriate) of glurina. When first precipitated, it is in the form of a jelly, yvhich dissolves in hot water, and deposites in small crys- tals as the solution cools. Of the remaining salts of glucina, there have been more List of or less examined, the hydrochlorate, hydrosulphate, sele-saltsof 8lu* nate, chromate, chromo-sulphate, oxalate, succinate, and described. acetate; but these are not of sufficient importance to be inserted. The rest of the salts of glucina, amounting in number to 49, are unknown. The salts of glucina may be known by the following General properties or marks. properties 1. They are much more soluble than the salts of yttria, and of glucina3 but a small proportion of them are capable of crystallizing. 2. They are precipitated by oxalate of ammonia, or by tartrate of potash; which circumstances sufficiently distin- guish them from the salts of yttria. ') X 346 SALTS Book I. Divition II. ----- SECTION XI. SALTS OF ALUMINA. Salts of aiu-Salts of Alumina are combinations of alumina with the what com- different acids. The foiloyving are the principal of these pounds. compounds. Hydrochlo- !• Hydrochlorate of Alumina.—This salt may be obtain- rate ofalu- ed by dissolving alumina in hydrochloric (muriatic) acid. It always contains an excess of acid. It is scarcely capable of crystallizing. It is either in the form of a gelatinous mass or of a yvhite powder. It is extremely soluble in wa- ter, and deliquescent in the air. When exposed to heat, it melts; its acid being dissipated, while its earthy base re- mains behind. Sulphate. II. Sulphate of Alumina.—This salt may be formed by dissolving alumina in sulphuric acid, evaporating the solu- tion formed to dryness, and afterwards dissolving the dry mass in water, and evaporating the solution until it crystal- lizes. It is very soluble in water, and has an astringent taste. It does not crystallize without difficulty. Its crystals consist of thin plates, which are soft and pliant, and have a pearly lustre. It is not altered by exposure to the air. When somewhat heated, it loses its water of crystallization and falls to powder. In a strong heat, its acid is decom- posed and dissipated, and the pure earthy base remains behind. It was never properly distinguished from the dif- ferent alum salts, before the memoirs of Vauquelin and Chaptal appeared on the nature of alum. C SUPERSULPHATE OF ALUMINA AND-POTASH. IIL I SUPERSULPHATE OF ALUMINA-AND-AMMONIA. Chemical 1. As these salts scarcely differ in properties, and can be nature of distinguished only by analysis, they will be described to- gether. They constitute, either singly, or mixed in different proportions, the very useful substance called alum. The account of alum, therefore, will be the account of these two salts. Alum; how 2. Alum is obtained from different earths, whose princi- obtained. pal ingredients are sulphur, and clay or alumina. These earths are called aluminous, and are of several different kinds. Some of them contain sulphuret of iron (pyrites), and others, variable quantities of bituminous matters. The outline of the process is this: The alum earth is roasted, in order to acidify the snlphur which it contains. The sul- phuric acid, thus formed, combines with the alumina, SALTS OF ALUMINA. 347 which, in this state of combination, becomes soluble. The Cbap.IV. roasted earth is next lixiviated, and the solution obtained, concentrated by evaporation, and afterwards putrid urine or a solution of common potash, added. The alum becomes deposited in crystals, which are sometimes mixed with those of sulphate of iron (green vitriol), in case the alu- minous earth should have contained sulphuret of iron. 3. The sulphate of alumina, first formed, after being Use of pot- lixiviated, requires to be mixed with potash or ammonia, ash and am- or some substance which furnishes these alkaline bases; theprocess, for it must be recollected, that alum is a triple salt, which explained. contains either potash or ammonia, or both these substan- ces, as well as alumina, combined yvith sulphuric acid. When putrid urine is used in the manufacture, ammonia is the second base which the alum contains; as this secretion, after having undergone the putrefactive process, contains a large proportion of ammonia, and only a minute quantity of potash. 4. Sometimes alum is prepared by burning sulphur in Another chambers, whose floors are covered with fraements of ametho to the aluminous lixivium, was absolutely necessary for the formation of alum; unless indeed the earth, from which it may have been manufactured, should contain pot- ash. Various conjectures were made, as to the part which potash performed in the manufacture; but nothing decisive was known on the subject, before Vauquelin and Chaptal published their experiments, by which they proved incon- testably that alum is a triple salt, composed of sulphuric acid, united to alumina and potash, or alumina and am- monia. Alum des- 7. Alum is a crystallized salt, capable of changing vege- cribed. table blues to red, and always containing an excess of acid. Its taste is sweetish and very astringent. Its specific gra- vity is 1*71. When exposed to the air, it effloresces slightly. It is soluble in from 15 to 20 times its weight of cold wa- ter, and in three-fourths of its weight of boiling water. When exposed to a gentle heat, it undergoes the watery fusion. In a pretty strong heat, it foams and swells, and loses about 44 per cent, in water of crystallization. The residue, after this exposure to heat, is called calcined or burnt alum. In a very violent heat, it has the greater part of its acid dissipated. Homberg'a The principal ingredient in Homberg's pyrophorus is pyropho- alUm. To form this substance, three parts of alum and one formed. Part °f sugar or flour are melted in an iron ladle, and the heat continued, until the mixture becomes blackish and ceases to swell. It is then reduced to fine powder, and exposed to a sand heat in a phial, until a blue flame issues from its mouth. After burning a minute or tyvo, it is withdrawn from the fire and allowed to cool. The substance, thus formed, is the pyrophorus. It has the singular property of catching fire, yvhenever it is exposed to the open air, espe- cially if the atmosphere be moist. its disco- This substance was accidentally discovered, about the vei7- beginning of the 18th century, by Homberg. It was for a long time supposed that alum is an essential ingredient in it; but it has been ascertained, that, if alum be deprived of its potash, it will not form pyrophorus. According to Davy and Coxe, its properties depend upon the presence of a small portion of potassium, which they suppose to be de- veloped, during a partial decomposition of the potash, by the agency of heat. When a certain excess of potash is added to an alum li- quor, the salt does n>t crystallize in the usual form, and, from the shape of its crystals, is called cubic alum. If a still larger quantity be added, the liquor deposites no crys- SALTSTOF ALUMINA. 349 uls, but lets fall a number of flakes. Both these substances Chap. iv. mav b« considered as varieties of alum. 8. Supersulphate of alumina-and-potash is composed of Composi- Sulphuric acid 160—four atoms. tion of one a i • er\ species of Alumina 50— a|um. Potash 46—one atom, nearly. Supposing three atoms of sulphuric acid combined with the alumina, and the remaining atom, with the atom of potash; then the composition of this salt would be Sulphuric acid 120—three atoms. Alumina 50— Forming 170 sulphate of alumina; combined yvith Sulphuric aciu 40—one atom. Potash 46—one atom, nearly. Forming 86 sulphate of potash. And, supposing the sulphate of alumina to contain three atoms of earthy base, then the atom or combining weight of alumina would be represented by 16*6. 9. Alum is of indispensable utility in the arts. To enu-Alum, very merate all its uses could not be done, consistently with u*eful m the plan of this compendious yvork. It is employed prin- ' cipally in tanning, and as a mordant in dyeing. 10. In the materia medica, alum is a very powerful an active astringent. On account of this property, it was formerly the'm^teria used internally for restraining haemorrhages; but it now medica. yields in efficacy to many other articles. Its dose is from ten to twenty grains. In large doses, it is apt to produce nausea. Externally, it is used in solution, as a repellant lo- tion and in astringent collyria. It forms a good injection in certain stages of gleet, and in fluor albus. It enters into the composition of several pharmaceutical preparations of acknoyvledged efficacy. When deprived of its water of crys- tallization, in the form of burnt alum, it acts as an escarotic. IV. Sulphate of Alumtna-and-Potash; Sulphate of Alumi- \\am 8atu, na-and-Ammonia.—Formerly called, Alum saturated with its p*"1 witb> earth.—These two salts may be described together, as theylts eart are formed by saturating different species of alum with alumina. They are prepared by boiling a solution of alum with pure alumina. They are both in the form of a tasteless insoluble powder, which is incapable of crystallizing. They are not altered by exposure to the air. In a verv violent heat, part of their acid is driven off. The addition of sul- phuric acid converts them into alum. They have not here- tofore been applied to any useful purpose. 350 SALTS. Book I. Division II. Nitrate of alumina. Carbonate. Acetate. Mellate of alumina, the mellite of minera- logists. V. Nitrate of Alumina.—When alumina is dissolved in nitric acid, this salt may be obtained in crystals by evapo- ration. It has an acid and astringent taste. It is exceedingly soluble in water. In the air, it attracts moisture and deli- quesce.-.. When heated, the acid is readily driven off, and the earhy base remains behind in a state of purity. VI. Carbonate of Alumina.—It is not completely settled whether this salt can exist. In the dry state, it cannot be obtained; but it has been ascertained, that water saturated with carbonic acid is capable of dissolving a portion of alumina. The combination, however, is destroyed by mere exposure to air. VII. Phosphate of Alumina.—This salt may be formed by saturating phosphoric acid with alumina. It is a taste- less insoluble powder. VIII. Hydrofluate qf Alumina.—Usual chemical name, Fluate of Alumina—This salt may be formed by pouring hydrofluate (fluate) of potash into a solution of supersul- phate of alumina-and-potash (alum). It is in the form of a white powder, insoluble in water, but soluble in an excess of acid. After having been well dried, it is nearly insoluble in acids. IX. Acetate of Alumina.—When acetic acid is digested upon alumina recently precipitated, by evaporation this salt may be obtained in needle-form crystals, which have an astringent taste, and are very deliquescent in the air. This salt is employed in the processes of dyers and calico prin- ters. X. Mellate of Alumina.—This salt exists native under the name of mellite. It is the only substance in which mellitic acid has hitherto been found. It may be formed artificially by dropping mellitic acid into a solution of sul- phate of alumina. When thus formed, it assumes the ap- pearance of a white flaky powder. List of salts Besides the salts of alumina just described, there have ot aiumma been more or less noticed by chemists, the sulphite, sele- not des- , . J , , cribed. nate, borate, arseniate, tungstate, sulphocyanate, urate, purpurate, gallate, oxalate, sorbate, succinate, tartrate, po- tasso-tartrate, benzoate, saclactate, camphorate, malate, suberate and zumate; but these salts are not of sufficient importance to be described. The rest of the salts of alu- mina, amounting in number to 36, are unknown. General The salts of alumina may be known by the following properties pr0perties or marks. ot the salts r r .... , , , • j of alumina. 1. A large majority of them are soluble in water, and but very few capable of crystallizing. SALTS OF ZIRCONIA. 351 2. They have a sweet and astringent taste. In this parti- Chap.IV. eul ir, however, they resemble the salts of yttria and glu- cina. 3. They are not precipitated by oxalate of ammonia or tartaric acid; which circumstances sufficiently distinguish them from the salts of yttria. 4. If sulphuric acid, and afterwards sulphate of potash be added to a salt of alumina, crystals of supersulphate of alumina-and-potash (alum) will speedily make their ap- pearance. SECTION XII. SALTS OF ZIRCONIA. Salts of Zirconia are combinations of the different Salts of zir- acids with the salifiable base zirconia. Only five of these conia' wh.at ..... . ' compounds. compounds will be noticed. I. Hydrochlorate of Zirconia.—Usual chemical name, Hydrochlo- Muriate of Zirconia.—-When hydrochloric (muriatic) acid rate. of Eir" is poured upon newly precipitated zirconia, the latter be- con,,■ comes dissolved, and, by proper evaporation, this salt may be obtained in small transparent needle-form crystals, which become opaque in the air. It is colourless, and very solu- ble in yvater. Its taste is very astringent. When exposed to heat, it is decomposed. II. Sulphate of Zirconia —This salt may be formed by Sulphate. dissolving zirconia in sulphuric acid, and evaporating the solution to dryness. It is usually in the form of a white powder; but it may be obtained in crystals. It is tasteless, insoluble in water, and not altered by exposure to the air. By exposure to heat, its acid is readily driven off. III. Nitrate of Zirconia.—This salt maybe formed by Nitrate- dissolving newly precipitated zirconia in nitric acid. It always contains an excess of acid. It is but sparingly solu- ble in water. Its taste is astringent. When exposed to heat, it suffers decomposition. IV. Carbonate of Zirconia.—This salt may be formed by precipitating an acid solution of zirconia by means of the carbonate of potash or of soda. It is a tasteless white powder. When heated, its acid is driven off. V. Hydrofluate of Zirconia.—Usual chemical name, Fluate of Zirconia.—This salt is precipitated in the form of an insoluble white powder, when hydrofluate (fluate) of potash is added to hydrochlorate (muriate) of zirconia. 352 SALTS. BookL Of the remaining salts of zirconia, there have been more Division II. or iess examined, the sulphite, selenate, bor .te, phosphate, List of salts gallate, oxalate, acetate, tartrate, benzoate, saclactate, citrate notZd7scrib-ant^ malate» Dut these salts are not of sufficient importance ed. to be noticed. The rest of the salts of zirconia, amounting to 46, are unknown. properties The following circumstances are characteristic of the of the salts salts of zirconia. of zircoma. }> They have an astringent taste, which is harsh and disagreeable. 2. They are decomposed by all the alkaline and earthy salifiable bases, zirconia being precipitated. SECTION XIII. SALTS OF THORINA. Salts of Salts of Thorina are combinations of thorina with the thonna; different acids. But four of these compounds have been what eom- .... . . r pounds. distinctly examined. Hydrochlo- I. Hydrochlorate of Thorina.—Usual chemical name, rate of tho- j^Ur'tate 0J Thorina.—This salt may be formed by dissolv- ing thorina in hydrochloric (muriatic) acid. It may be ob- tained in a syrupy mass, which does not deliquesce in the air, but dries and becomes yvhite like enamel, by evaporat- ing the solution in a moderate heat; but it cannot be made to crystallize. Sulphate. II. Sulphate of Thorina.—-This salt may be formed by dissolving thorina in excess of sulphuric acid, and evapo- rating the solution obtained, until it forms crystals. It has a strong styptic taste, and is not altered by exposure to the air. Nitrate, III. Nitrate of Thorina.—This salt may be formed by dissolving thorina in nitric acid. The solution takes place very readily, unless the thorina has been previously exposed to a red heat; in which case, it is effected by long boiling only. The solution cannot be made to crystallize, but forms a mucilaginous mass, which becomes liquid by exposure to the air. It is converted, by evaporation in a moderate heat, into an opaque white mass similar to enamel, and in a great measure insoluble in yvater. Carbonate. IV. Carbonate of Thorina.—This salt is easily formed by precipitating an acid solution of thorina by carbonate of potash or of soda. Thorina seems to have considerable SALTS OF OXIDIZED IRON. 353 affinity for carbonic acid. When newly precipitated, during Chap.IV. the process of drying it attracts this acid from the air. What other salts this newly discovered salifiable base is eapable of forming has not been ascertained. The following circumstances are characteristic of the General salts of thorina. ofoie's'aUs 1. They are precipitated by oxalate of ammonia. of thorina. 2. When the nitrate or hydrochlorate of thorina is eva- porated by a strong heat, it leaves, on the edges of the vessel employed, an opaque white film, which has the ap- pearance of enamel. SECTION XIV. SALTS OF SILICA. In consequence of the property, which hydrofluoric Salts of sl- (fluoric) acid possesses, of dissolving glass or flint, it was ,IC* d° notj formerly supposed that at least one salt of silica exists, speaking, More recent researches, however, have proved, that the exist- combination of hydrofluoric (fluoric) acid and silica is not a salt, but a peculiar acid. In strict propriety, therefore, there is no such combination as a salt of silica. Silica is consequently not a salifiable base; but it has been classed as such, as giving it the most natural position, which it could assume in the arrangement adopted. SECTION XV. SALTS OF OXIDIZED IRON. Salts of Oxidized Iron are combinations of the protox- Salts of oxr ide or peroxide of iron with the different acids. The fol- 5n,'zed iron; lowing are the most important of these salts. pounds?"1 Hy drochloric acid forms one salt with each of the oxides Oxidized of iron,* and a triple salt with the peroxide and ammonia, ihree'saks I. Hydrochlorate of Iron.—Usual chemical name, j^L?-with hydro- riate of Iron.—This salt may be formed by dissolving iron^r,c ———__—————_______——_____________ 1. Hydro- ._. .,.......... chlorate of The reader has already had explained to him the meaning of the prefixes ir0n. proto and per, as applied to oxides It may now, very probably, be a matter of inquiry with him, hou salts, containing different oxides of the same metal, arc to be distinguished from e:ich other. Dr Thomson has adopted the plan of prefix- es:, to the salts themselves. th» syllables, distinguishing the oxides vhich thev 2 Y 354 SALT? Book I. filings in hydrochloric (muriatic) acid. The solution must Division II. be kept from ^ a^ ^^ ^ evaporation, yields the salt in crystals. The salt has a pale-green colour, and is extremely soluble in water. Its solution attracts oxygen from the air, or from nitric acid, and the salt itself becomes converted into a perhydrochlorate (permuriate). Its solution also is ca- pable of absorbing deutoxide of azote (nitrous gas) in large quantity; and yvhen saturated, it acquires a dark-broyvn co- lour, and a much more astringent taste than the salt has in its usual state. When the salt is exposed to a red heat, it is decomposed, and converted into a protochloride of iron; yvater being at the same time formed. II. PERHYDROCHLORATE OF IRON. (Usual chemical name, Permuriate of Iron.) 2. Perhy- j# This salt may be formed by dissolving peroxide of drochlorate. • , , ,,•✓ . . N -X , ,5r • t_ ofiron. iron in hydrochloric (muriatic) acid, and evaporating the solution to dryness. It is an uncrystallizable, deliquescent, orange-coloured mass. In solution, it has a deep-brown co- lour, a peculiar odour, and, even when very much diluted, an exceedingly astringent taste. Like chlorine, it tinges ani- mal and vegetable substances of a yellow colour. When distilled, it suffers decomposition; the hydrogen of the acid combines with a portion of the oxygen of the peroxide, reducing the latter to the state of protoxide, and forms water; while its chlorine passes over. When exposed to a red heat, water is formed and dissipated, and it is convert- ed into a perchloride of iron. Tincture of 2. The London colleges form a tincture of this salt, under this salt; the tjtje Q{ tne tincture qf muriated iron. They dissolve half a pound of percarbonate of iron (rust of iron) in three pounds of hydrochloric (muriatic) acid, and evaporate the solution, so as to form one pint of liquid, to which they add three pints of alcohol. The other colleges prepare a simple hydrochlorate (muriate) of iron for the formation of the tincture. But as it is very doubtful whether the simple hy- drochlorate will dissolve in alcohol; and, if it will, as the fact is yvell ascertained that it is very liable, by exposure to air, may contain. This plan I proposed in a short paper, published in the Memoirs of the Columbian Chemical Society, in 1813; but I was not then aware that it had been adopted by Dr. Thomson The plan, however, although original with my- sedf, and sanctioned by the usage of this respectable chemist, upon further consi- deration, I propose to modify in the following manner: Whenever a protoxide is the base of a salt, which is by far most generally the case, I propose to employ no prefix; uhile, on the other hand, when a peroxide constitutes the base, the prefix/» 360 SALTS. Book I. appear, however, that the animal substances, by being igni- DiTision II. ted with carbonate of potash, form a cyanodide of potash. These substances appear to be essential to the process, only by furnishing the necessary quantity of azote for the for- mation of the cyanogen. On the supposition that the ferro- cyanic acid is a compound of hydrocyanic acid and iron, then the explanation of the formation of the salt would seem to be this: at the moment that the sulphate of iron is added to the cyanodide of potash, water is decomposed, and at the same time, a portion of the oxide of iron of the sulphate, deoxidized. The cyanogen of the cyanodide, alter being converted into ferrocyanic acid by combining with the hydrogen of the decomposed yvater and the reduced iron of the sulphate, then unites to the unreduced portion of the oxide, previously converted to the state of peroxide, so as to form the perferrocyanate. After the perferrocya- nate is separated, the remaining liquid is a solution of sul- phate of potash. The supersulphate of alumina-and-potash (alum), which is employed, is for the purpose of diluting the colour. Hence the Prussian blue of commerce ahvays con- tains a portion of alumina. It is yvashed with diluted hy- drochloric acid, in order to dissolve away some oxide of iron which remains in excess. Properties 3. Perferrocyanate of iron is in the form of a powder of a of the per- deep bhie colour. It is insoluble in water, and scarcely dis- anate. solves in acids. It remains unaltered in the air. When de- composed by heat, cyanogen is driven off, and oxidized iron remains behind. Pergallate XXII. Pergallate of Iron.—This salt may be formed by of iron. dropping gallic acid into a peroxidized salt of iron. It is in the form of a black precipitate, very fine and light, and remaining a long time suspended. If a portion of mucilage or syrup be added to the water holding the black precipi- tate, it becomes permanently suspended, and constitutes the Chemical liquid called writing ink. Ink is generally made by adding MTitrngink.a quantity of water to a mixture of powdered nut-galls and sulphate of iron of commerce. This sulphate is a mixture of the two sulphates of iron; and accordingly, only part of it is proper to produce the precipitate of pergallate of iron. The portion of the sulphate, containing the protoxide, is found to form yvith gallic acid, a combination, which is colourless, but which, by attracting oxygen from the air, soon becomes converted into a pergallate and turns black. These facts supply the reason why some inks, at first very pale, become afterwards quite black by exposure to air. XXIII. Per succinate of Iron.—When succinate of soda is dropped into solutions of the persalts of oxidized iron, this SALTS OF OXIDIZED IRON. 361 salt precipitates in the form of brownish-red fhkes. Succi- Cb-p.iv. nate of soda is therefore a very excellent test of the pre- sence ot peroxide of iron, in solutions. Acetic acid forms a distinct salt with each of the oxides of Oxidized iron forms ,ron* two salts XXIV. Acetate of Iron.—This salt maybe formed by with acetic dissolving sulphuret of iron in acetic acid. It is in the form ac,d- of cry stals of a green colour, and sweetish styptic taste. XXV. Per acetate of Iron.—This salt may be prepared, either by mixing together sulphate of iron and acetate of lead (sugar of lead), and exposing the mixture to the air, or by dissolving iron in the impure acetic acid obtained by- distilling wood. It is deliquescent, and cannot be made to crystallize. When evaporated, it assumes the form of a jelly. Its solution in water has a brownish-red colour. It is much employed by calico printers; it being the most easily de- composed of any of the persalts of oxidized iron. When prepared with alcohol, it forms the tincture of acetated iron, of the Dublin college. Tartaric acid forms one salt with protoxide of iron, and Protoxide one salt with protoxide of iron and potash. terTuito"1 XXVI. Tartrate of Iron.—When tartaric acid is poured two tar- into a solution of sulphate of iron, and the mixture heated, traies' this salt may be obtained in the form of crystals yvhich are sparingly soluble in water. XXVII. TARTRATE OF POTASH-ANDIRON. (Old names, Chalybeated Tartar—Tartarized Iron.) 1. This salt may be obtained by boiling a mixture of tyvo 2. Potasso- parts of bitartrate of potash (cream of tartar), and one parttartrate- of iron filings, previously made into a paste with yvater, in a sufficient quantity of this liquid. The extra atom of acid in the bitartrate becomes saturated yvith protoxide of iron. By proper evaporation, the salt may be obtained in crystals— The Dublin college form this triple salt by boiling one part of carbonate of iron and tyvo parts of bitartrate of potash, in thirty-two parts of yvater. The liquor thus obtained is filtered, and evaporated for crystallization. 2. Tartrate of potash-and-iron is in the form of small needle-shaped crystals, possessing a chalybeate taste. It is very soluble in yvater. 3. When this salt is employed as a medicine, it acts as a Its medical tonic and aperient. From its chemical composition, there P10lHrtlcs is reason to believe that it yvould be of service in many- cases of chronic disease. It certainly deserves more atten- 2 Z 362 SALTS. Book I. tion than is generally paid to it by the medical profession DivisionII. m this country. its jogg is from 10 to 30 grains# Chalybeate or ferrated wine may be considered as th'19 triple salt dissolved in yvine; since this liquid dissolves iron, only in consequence of the bitartrate of potash (tartar), which it contains. To make a uniform chalybeate wine, it yvould be preferable to dissolve a determinate quantity of the triple salt, ready formed, in some yvine. Peroxide of Tartaric acid forms but one salt with peroxide of iron. iron forms vvxriTt r» • • i 1 but one tar- AAV 111. Pertartrate of Iron.—When iron is dissolved trate. jn tartaric acid, and heat applied to the solution, this salt becomes formed. It has a red colour. It is not crystalliz- able by evaporation, but assumes the form of a jelly. List of salts Of the remaining salts of oxidized iron, there have been ironXiioted more or less examined by chemists, the sulphite, hyposul- described. phite, hydrosulphate, selenate, borate, molybdate, antiino- rnate, sulphocyanate, purpurate, oxalate, benzoate, citrate, mellate, malate, lactate, suberate, zumate, and boletate; but these salts are of too little importance to be described. The rest of the salts of .oxidized iron, amounting to 31, are un- known. General The salts of oxidized iron may be recognised by the ofX'saits following properties or marks. of oxidized 1. The majority of them are soluble in water; and in iron. general, they have a greenish or yellowish-red colour, and an astringent taste. 2. Ferrocyanate (triple prussiate) of potash, when drop- ped into their solutions, occasions a precipitate, which is either deep blue, or acquires this colour by exposure to the atmosphere. This precipitate is the perferrocyanate of iron (Prussian blue). 3. Phosphate 'of soda occasions a white precipitate in their solutions. 4. Succinate of ammonia precipitates the peroxidized salts of a flesh-colour, but has no effect upon the protoxi- dized salts. SALTS OF OXIDIZED NICKEL. 363 Chap. IV. SECTION XVI. SALTS OF OXIDIZED NICKEL. Salts of Oxidized Nickel are combinations of the Salts of oxi- oxides of nickel with the different acids. Only three of ^j2^™0*' these compounds will be noticed. compounds. I. Hydrochlorate of Nickel.—Usual chemical name, Hydrochio- Muriate of Nickel.—When pure nickel is dissolved in hy-™teofmck" drochloric acid assisted by nitric acid, and the solution evaporated, this salt is obtained in crystals of an apple- green colour. In the air, they at first deliquesce, but, by long exposure, suffer decomposition. When somewhat heated, the salt becomes yellow, and loses about 55 per cent, in water of crystallization; but its original quantity is restored again, when it is exposed to the air, by the ab- sorption of moisture. In a stronger heat, it is decomposed. II. Sulphate of Nickel.—This salt may be formed by dis- Sulphate. solving pure nickel in sulphuric acid, occasionally assisted by nitric acid. It is in the form of crystals, yvhich have a beautiful green colour, and are not altered by exposure to the air. It has an astringent taste, and is very soluble in water. When heated, it swells without melting, and as- sumes a yellow colour, owing to the loss of its water of crystallization. III. Nitrate of Nickel.—When nickel is dissolved in Nitrate. nitric acid by the assistance of heat, the solution, by evapo- ration, yields this salt in crystals. These crystals, by expo- sure to air, at first deliquesce, but afterwards fall to pow- der, and gradually lose their acid. Of the remaining salts of oxidized nickel, there have List of salts been more or less examined by chemists, the ammonio- of oxidized sulphate, potasso-sulphate, ferro-sulphate, selenate, ammo- described. nio-nitrate, carbonate, borate, phosphate, arseniate, chro- mate, molybdate, sulphocyanate, purpurate, oxalate, acetate and zumate; but these salts are of too little importance to be noticed. The rest of the salts of oxidized nickel, amount- ing to 48, are unknown. The salts of oxidized nickel may be recognised by the General folloyving properties or marks. properties 1. They are generally soluble in water; and their solu-of oxidized tions have a beautiful green colour. nickel. 2. When ferrocyanate (triple prussiate) of potash is drop- ped into their solutions, a milk-white precipitate is formed. 3. Hydrosulphate (hydrosulphuret) of potash, occasions a black precipitate. 364 SALTS Book I. Division II. SECTION XVII. Salts of oxi- dized co- balt; what compounds, Hydrochlo' rate of co- balt. Sulpliate. Vitrate. SALTS OF OXIDIZED COBALT. Salts of Oxidized Cobalt are combinations of the pro- toxide of cobalt with the different acids. The peroxide is not known as a salifiable base. Only four of these com- pounds will be noticed. I. Hydrochlorate of Cobalt—Usual chemical name, Mu- riate of Cobalt.—This salt may be formed by dissolving cobalt in hydrochloric (muriatic) acid, assisted by nitric acid. The solution, when sufficiently concentrated, deposites small deliquescent crystals, which are at first blue, but af- terwards become red by the absorption of moisture. This salt, when dissolved in water, forms one of the best sym- pathetic inks known. When the solution is very much dilu- ted, it is nearly colourless; and if employed to trace letters on paper, the writing remains invisible in the cold; but if the paper be gently heated, the letters become visible of a fine green colour. When the salt is heated to redness in a retort, those portions of it, which are in contact with the vessel, undergo decomposition, tinging, at the same time, the glass of a blue colour; the rest melts, and aftenvards sublimes in grey-coloured flowers, which are difficultly solu- ble in water. II. Sulphate of Cobalt.—When boiling sulphuric acid is digested upon cobalt, the metal is dissolved; and there is obtained a brownish-red mass, which, by solution and eva- poration, yields this salt in small needle-form crystals. It has a reddish-colour, and is not altered by exposure to air. When heated, it loses 42 per cent, in water of crystalliza- tion, and becomes converted into an opaque, rose-coloured mass. ... j- j III. Nitrate of Cobalt.—When nitric acid is digested upon cobalt with the assistance of heat, the solution obtain- ed, by evaporation, yields this salt, in the form of crystals, which are deliquescent in the air, and suffer decomposition by heat. . IV. Hydrofluate of Cobalt.—Usual chemical name, Fluate of Cobalt.— This salt may be obtained by dissolving pro- toxide of cobalt in hydrofluoric (fluoric) acid, and evapo- rating the solution formed. It is in the form of small red crystals, which contain a small excess of acid. When treat- ed with water, it is divided into two salts; a superhydro- fluate which remains in solution, and a neutral hydrofluate which precipitates in the form of a red powder. SALTS OF OXIDIZED MANGANESE. 355 Of the remaining salts of oxidized cobalt, there have been Chap. iv. more or less noticed by chemists, the selenate, ammonio- List of salts nitrate, carbonate, borate, phosphate, arseniate, antimoniate, of oxidized antimonite, sulphocyanate, purpurate, oxalate, acetate, tar- jjobaH» "j* trate, and zumate. The rest of the salts of oxidized cobalt, amounting in number to 46, are unknown. The salts of oxidized cobalt may be recognised by the General following properties or marks. properties 1. The greater number of them are soluble in water; and of oxidized their solutions, when containing a neutral salt, have a red- cobalt. dish colour. 2. Potash or soda, when dropped into them, occasions a blue precipitate. 3. Ferrocyanate (triple prussiate) of potash occasions a yellowish-brown precipitate, often having a shade of blue. SECTION XVIII. SALTS OF OXIDIZED MANGANESE. Salts of Oxidized Manganese are combinations of the Salts of ox- protoxide and peroxide of manganese with the different,dlzed raan" acids: the deutoxide is not known to enter, as a constitu- what com- ent, into any salt. Four only of these salts will be noticed. Pounds- I. Hydrochlorate of Manganese.—Usual chemical name, Hydrochio- Muriate qf Manganese.—This salt may be formed by dis- manganese solving protoxide or carbonate of manganese in hydrochloric acid. It is difficult to obtain it in crystals. It is transparent, and has a rose-red colour, and a caustic taste, which leaves a saltish impression upon the tongue. It speedily deliques- ces in the air. When exposed to heat, it undergoes the watery fusion; and if the temperature be increased to red- ness, the greater part of the acid is driven off. Sulphuric acid forms a salt with either the protoxide or Oxidized peroxide of manganese. manganese II. Sulphate of Manganese—-This salt may be obtained SSwiA by dissolving carbonate of manganese in sulphuric acid. It sulphuric is formed also, yvhen the peroxide is treated with sulphuric acid" acid, with the assistance of heat. The oxide becomes re- duced to the state of protoxide (oxygen being extricated in the gaseous form) and then dissolves in the acid. It is in the form of silky, needle-shaped crystals, of a sweetish taste. It is not altered by exposure to the air. After being 366 SALTS. Book I. dried, it is soluble in about three times its weight of cold l>ivi8ionI1- water. III. Persulphate of Manganese.—This salt may be ob- tained by distilling sulphuric acid off the peroxide of man- ganese. A mass is thus obtained, which, by treatment yvith water, affords a violet-coloured liquor, holding this sulphate in solution. It cannot be obtained easily in crystals. When the solution is evaporated, it is converted into a jelly-like mass, intermixed with soft crystals of little permanency. When evaporated to dryness, it yields thin red-coloured crusts, which are formed by successive precipitations from the surface. Nitrate of IV. Nitrate of Manganese.—Nitric acid dissolves man- manganese. ganese wjtn effervescence, owing to the formation of deu- toxide of azote (nitrous gas). It acts with great difficulty upon the peroxide; but, after long digestion, the solution is effected. Its solvent power is greatly assisted by the addi- tion of sugar or gum, as the solution is going on, and a quantity of carbonic acid is emitted. This circumstance shows, that part of the oxygen of the peroxide is yielded up to combine with the carbon of the substances added. The easiest method, however, for forming this salt, is tb dissolve the carbonate in nitric acid, and to evaporate the solution cautiously. The salt is thus obtained in needle- form crystals, semi-transparent and of a yvhite colour. It has a sharp bitter taste, and is soluble in water and deli- quescent in the air. list of salts Besides the four salts just described, there have been of oxidized more or \ess noticed by chemists, the hydrosulphate, sele- •jmitted. nate, carbonate, phosphate, arseniate, chromate, tungstate, antimoniate, hydrofluate, sulphocyanate, oxalate, succinate, acetate, tartrate, potasso-tartrate, benzoate, citrate and zu- mate of manganese; but these salts are of too little im- portance to be described. The rest of the salts of oxidized manganese, amounting in number to 43, are unknown. General The salts of oxidized manganese may be knoyvn by the lfthClt,?u following properties or marks. of oxidized 1. Their solutions are precipitated, by the carbonate of manganese. p0tash or soda, of a yvhite or reddish colour, becoming black by exposure to air. This precipitate is a carbonate of manganese. 2. Ferrocyanate (triple prussiate) of potash occasions a white precipitate. 3. Hydrosulphate (hydrosulphuret) of potash occasions a white precipitate. SALTS OP OXIDIZED CERIUM- 367 Chap. IV. SECTION XIX. SALTS OF OXDDIZED CERIUM. Salts of Oxidized Cerium are combinations of the ox- Saitsofoxi- iocs ot cerium with the different acids. Five only of these d.ized_ce* compounds will be noticed. what'com- • i t_ •» <• • pounds. Hydrochloric acid combines with the peroxide of cerium only. I. Perhydrochlorate of Cerium.—Usual chemical name, Perhydro- Muriate of Cerium.—When peroxide of cerium is treated chlorate Qf with hydrochloric acid, a solution is obtained, which, by concentration, may be mz.de to yield this salt in crystals of a yellowish-white colour. It has an astringent and sweet taste, and deliquesces in the air. When exposed to heat, it is completely decomposed. Sulphuric acid forms a distinct salt with each of the oxides Oxidized of cerium. cerium II. Sulphate of Cerium.—This salt may be formed by suiphates; dissolving the protoxide or carbonate of cerium in sulphuric acid. The solution is colourless and has a sweet taste, and readily yields the salt in crystals. III. Persulphate of Cerium—By digesting peroxide of eerium, for some time, in diluted sulphuric acid, there is obtained an orange-coloured solution, which yields, by eva- poration, this salt in needle-form crystals. Its colour is partly lemon-yellow and partly orange. It is not soluble in water, unless it contain an excess of acid; in which case its solution has an acid and sweet taste. When exposed to the air, it falls into a yellow powder. Nitric acid forms a distinct salt with each of the oxides ofandtwoui- cerium. IV. Nitrate qf Cerium.—When nitric acid is poured upon the protoxide or carbonate of cerium, this salt is readily obtained in solution. The solution, which is colour- less and possesses an austere sweet taste, always retains an excess of acid, and cannot be made to crystallize without difficulty. V. Pemitrate of Cerium.—When peroxide of cerium is dissolved in hot nitric acid, the solution yields this salt in small white crystals, which deliquesce yvhen exposed to the air, and suffer decomposition by heat. trates. Of the remaining salts of oxidized cerium, the folloyving List of salts have been noticed by chemists; namely, the potasso-sulphate,of oxidized 368 SALTS. Book I. sulphite, selenate, carbonate, phosphate, arseniate, molvb- Division II. date, oxalate, succinate, acetate, tartrate, benzoate and ci- cerium trate. The rest of the salts of oxidized cerium, amounting omitte . in number to 48, are unknoyvn. General The salts of oxidized cerium may be distinguished bv ofSheS the foUowing maTks. of oxidized !• The protosalts are white, and the persalts, yellow. cenum. 2. Their solutions in water have a sweet taste. 3. Hydrosulphate (hydrosulphuret) of potash occasions a white precipitate, consisting of the protoxide. 4. Ferrocyanate (triple prussiate) of potash occasions a milk-white precipitate. SECTION XX. SALTS OF OXIDIZED URANIUM. Salts of Salts of Oxidized Uranium are combinations of the uranium- oxides of uranium with the different acids. Four of these ■what com- salts only will be noticed. pounds. Hydrochlo- I. Hydrochlorate of Uranium.—.Usual chemical name, rate of ura- Muriate qf Uranium.—Hydrochloric acid scarcely acts upon uranium in the metallic state, but dissolves the protoxide. The solution formed yields this salt in crystals, which have a yellowish colour, and are deliquescent in the air. Sulphate. II* Sulphate qf Uranium.—Sulphuric acid, vvhen cold, has very little action upon uranium; but when diluted and assisted by heat, it dissolves its protoxide, and the solution obtained yields needle-formed crystals of this sulphate. This salt has a lemon-yellow colour. It dissolves in some- what more than half its yveight of cold water, and in a less quantity of boiling water. When exposed to a red heat, its acid is entirely dissipated, and nothing remains but the pure protoxide. Protoxide Nitric acid forms a neutral salt and a subsalt with protox- rf^ntom jde Qf uranium. nitrates. HI* Nitrate of'Uranium.—This salt may be formed by dissolving protoxide of uranium in nitric acid. It is in the form of lemon-yellow crystals, which are greenish on the edges; but if it contain an excess of acid, the crystals are entirely greenish. Cold war. r dissolves about twice its tveight of this salt. Boiling yvater dissolves any quantity; SALTS OF OXIDIZED ZTNC. 369 the water of crystallization being sufficient to effect the so- Chap. iv. lution at the boiling temperature. When exposed to the air, ' heated to about the temperature of 100°, it very soon falls into a white powder; but in a cold and damp situation, it deliquesces, and is converted into a liquid. IV. Subnitrate of Uranium.—This salt may be formed by heating nitrate of uranium, until it becomes of an orange- yellow colour, and then treating it with water. The portion of it, yvhich remains undissolved, is the subnitrate. It is in the form of a powder of a lemon-yellow colour. Besides the four salts just described, there have been List of salts noticed, by different chemists, the selenate, phosphate, ar- of oxidized , , , '., ' r r 7 uranium semate, molybdate, tungstate, sulphocyanate, acetate and omitted. tartrate of uranium; but these salts are of too little im- portance to be described. The rest of the salts of oxidized uranium, amounting to 52, are unknown. The salts of oxidized uranium may be distinguished by General the following marks. properties 1. The greater number of them are soluble in water; and0f0xfdized the solutions have a yelloyv colour. uranium- 2. Potash and soda, or their carbonates, occasion a white precipitate, yvhich is soluble in excess of these salifiable bases. 3. Ferrocyanate (triple prussiate) of potash occasions a brownish-red precipitate, which is not in the form of flakes. 4. Hydrosulphate (hydrosulphuret) of potash occasions a brownish-yellow precipitate. SECTION XXI. SALTS OF OXIDIZED ZINC. Salts of Oxidized Zinc are combinations of the oxide Salts of ox- of zinc with the different acids. The following are theidized zinc» most important of these salts. p0hunds.m I. Chlorate of Zinc—Former chemical name, Hyperoxy- chlorate of muriate of Zinc.—Chloric acid dissolves zinc without ef- zinc. fervescence, and the solution contains both chlorate and chloride of zinc. Hence, it is evident, that part of the acid is decomposed; the oxygen of the decomposed portion oxidizes a part of the zinc, with yvhich the undecomposed portion combines in the form of chlorate of zinc; tvhile its chlorine forms a chloride with the metallic zinc. This salt, however, may be obtained, in a separate state, bv dissolv- 3 A 370 SALTS. Book i. ing carbonate of zinc in chloric acid, and evaporating the ivisionll. soiUIjon nmi\ it crystallizes. It has a very astringent taste. ^ On burning coals, it fuses and produces a yellow light, but does not detonate. Hydrochlo- II. Hydrochlorate of Zinc.—Usual chemical name, Mu- zinc. riate of Zinc—This salt may be formed by dissolving zinc in hydrochloric acid. The solution is attended yvith effer- vescence, owing to the extrication of hydrogen gas. When evaporated, it does not crystallize, but forms a mass re- sembling jelly. When distilled, a portion of its acid sepa- rates, and a solid mass is left behind, which is very soluble in water, and attracts moisture from the air, so as to assu ne a gelatinous consistency. When evaporated to dryness, and afterwards exposed to a red heat in a glass vessel with a narrow orifice, it is converted into chloride of zinc. III. Iodate of Zinc—This salt mav be obtained by dis- solving carbonate of zinc in iodic acid. After an interval of a feyv hours, the salt precipitates in spherical grains. It is but sparingly soluble in yvater. IV. Hydriodate of Zinc—This salt may be formed by heating iodine, yvith excess ot zinc, under yvater. The water at first acquires a deep brown colour; but afterwards, if the heat be continued, it becomes colourless. It now constitutes a solution of this hydriodate. It cannot be made to crystal- lize. When evaporated to dryness and fused, it is converted into a crystallized iodide of zinc. V. SULPHATE OF ZINC. (Common names, Vitriolated Zinc.— White Vitriol.) Sulphate of 1. This salt may be formed by dissolving three parts of zim; zjnc filings in five parts of sulphuric acid, previously dilu- tained." ted yvith twenty parts of water. The solution, on being set aside, deposites the sulphate in crystals. 2. It is prepared by the manufacturer by roasting native sulphuret of zinc (blende). By this measure, the sulphur becomes acidified, and the metal, converted into an oxide. The mineral, thus altered, is then dissolved in water, and the solution obtained, concentrated so far as that the sul- phate suddenly crystallizes in a mass, not unlike white sugar. In this state, it constitutes the white vitriol of com- merce. It is, however, impure, owing to admixture of iron, copper and lead. Apothecaries very frequently put up, in prescriptions, the impure sulphate of commerce; but, before being used medicinally, it ought always to be purified by solution, and mixture with a quantity of zinc filings. Zinc has the property of precipitating all metals from their solutions; and hence its use in the purification, as it throyvs SALTS OF OXIDIZED ZINC 371 down all the foreign metals, and takes their place. The im- Chap.IV. pure sulphate may be distinguished by its hiving yellow spots, and by letting fall, upon solution, a dirty brown sedi- ment. J. This salt was discovered in Germany about the mid- dle of the sixteenth century. It was first proved to contain zinc by Henkel and Newmann; but it yvas Brandt, yvho ascertained its composition completely. 4. Sulphate of zinc has a yvhite colour, and a metallic Proper- sty ptic taste. It dissolves in about two-thirds of its weightties' of cold yvater, rucl to anv amount in boiling water. Its spe- cific gravitv, when in the form of crystals, is 1-912; but, in an impure state as it occur* in commerce, it is 1*327. When exposed to heat, it speedily melts, then loses its water of crystallization, amounting to about 36 per cent, and at last, when the temperature is considerably raised, it parts with the greater portion of its acid. 5. It is composed of Sulphuric acid 40—one atom. Oxide of zinc 41—one atom. Giving 81 for the number .represent- ing the weight of its atom. 6. Sulphate of zinc is frequently used in medicine, and Uses iu with various intentions. When employed in small doses, itraedlcme- is said to act as a tonic. In doses of from ten grains to half a drachm, it acts as a very prompt emetic, and on this ac- count is generally preferred for the purpose of dislodging poison from the stomach. When given with this view, it ma) be exhibited, in urgent cases, in very large doses. In solution, it is frequently used as an injection in gonorrhoea, to act as a sedative and astringent application. It forms a part of the most efficacious astringent colly ria. In solution, along with supersulphate of alumina-and-potash (alum), it forms the compound alum water of the London college, formerly called Bates's alum yvater, which is frequently- used for the purpose of cleansing ulcers, and as a wash for cutaneous eruptions. VI. Nitrate of Zinc.—This salt may be formed by dis-Nitrate of solving zinc in nitric acid. The acid acts upon the metalzlQC- with great energy, and large quantities of deutoxide of azote (nitrous gas) are emitted. The solution is transpa- rent and colourless, and possesses a styptic taste. When sufficiently evaporated, it yields the nitrate in crystals. This salt is soluble in water, and deliquescent in the air. When heated on burning coals, it first melts, and then de- tonates with a red flame. In a strong heat, it is completely 37:2 SALTS. BookL decomposed, its acid being converted into deutoxide of Division II. azote and oxygen gas. VII. CARBONATE OF ZINC. (Common name, Calamine.) Carhonate 1. This salt may be formed by precipitating a solution of of zinc any sa|t 0f zinC) by means of the carbonate of potash or of soda. How pre- 2. For the purposes of medicine, it is prepared from ca- paredfor iamine a native carbonate of zinc, found abundantly in use in nip- • % ■__* dicine England, Germany, and other countries, by a process simi- lar to that for forming prepared carbonate of lime (chalk). The native carbonate has a variety of colours; the most usual are greyish, brownish, yellowish, or pale reddish. Its hardness is considerable. Before the blow-pipe, it de- crepitates and sublimes. It dissolves in many of the acids with effervescence. 3. It is composed of Carbonic acid 22—one atom. Oxide of zinc 41—one atom. Giving 63 for the number represent- ing the weight of its atom. Medical 4. This salt is used in medicine as an external applica- properties. t-lon oniy. it 1S employed in collyria for defluctions from the eyes, and as a drying application for moist running ulcers, and excoriations. It is usually applied in the form of a cerate. This cerate is called epulotic cerate. It is essen- tially the same with Turner's cerate. VIII. Hydrofluate of Zinc.—Usual chemical name, Flu- ate of Zinc—This salt may be obtained by dissolving zinc in diluted hydrofluoric acid; or by precipitating sulphate of zinc by means of hydrofluate of potash. It is a white, taste- less, insoluble powder. IX. ACETATE OF ZINC. Acetate ot 1. This salt may be formed by dissolving zinc in acetic zinc; how jj. or b mixing together the solutions of sulphate ot °btalned' zinc (white vitriol), and acetate of lead (sugar of lead). When obtained by the latter method, a double decomposi- tion takes place; and an insoluble sulphate of lead preci- pitates, while the acetate of zinc remains in solution. When- ever these two salts are prescribed in solution together, this double decomposition takes place; and an acetate ot zinc becomes formed. But this is not a good way to pre- scribe the acetate; as, in many cases, ignorant patients will shake the liquid, which contains it, in order to diffuse the SALTS OF OXIDIZED ZINC. 373 insoluble sulphate, which appears as a sediment, at the Chap.IV. bottom of the vial, under the impression that it may be a-- useful part of the medicine. The acetate, therefore, should always be ready prepared in the apothecaries' shops. It is easily formed by mixing the solutions of sulphate of zinc and acetate of lead together, and filtering the liquid obtain- ed to separate the insoluble sulphate. 2. Acetate of zinc may be obtained in crystals by evapo- Properties. rating its solution. It has a bitter metallic taste, and is very soluble in water. In the air, it suffers no alteration. When thrown upon live coals, it burns with a blue flame. When distilled, it yields water, an inflammable liquid, and some oil, and towards the end of the operation, the oxide of zinc sublimes. 3. This salt is very much used, in solution, as an injec- Medical tion in gonorrhoea. It appears to be one of the best metallic uses- preparations, which can be employed for abating inflamma- tion. It is ordered by the Dublin college to be dissolved in alcohol; under which form, it is called the tincture of ace- tate of zinc. When thus prepared, it is used as a stimulating eollyrium and injection. Of the remaining salts of oxidized zinc, there have been List of salts more or less examined by chemists, the ferro-sulphate, °f ox,<1lz?d cobalto-sulphate, sulphite, hyposulphite, hydrosulphate, se- ted.' lenate, borate, phosphate, arseniate, chromate, molybdate, tungstate, antimoniate, sulphocyanate, purpurate, oxalate, succinate, tartrate, potasso-tartrate, benzoate, citrate, ma- late, lactate, and zumate; but these salts are not of sufficient importance to be described. The rest of the salts, formed by this metallic oxide, amounting in number to 33, are un- known. The salts of oxidized zinc may be known by the follow- General ing properties or marks. properties 1. The greater number of them are soluble in water, and ofoxfdized their solutions are transparent and colourless. zinc. 2. Hydrosulphate (hydrosulphuret) of potash occasions a white precipitate, when dropped into them. 3. Ferrocyanate (triple prussiate) of potash occasions a white precipitate. 4. They afford no metallic precipitate, by metals, sus- pended in their solutions. 374 SAl.lv Protoxide of lead en- ters into two hydro- chlorates. Book I. Division If. ----- SECTION XXII. SALTS OF OXIDIZED LEAD. dized°iead''Salts of 0ximZED Lkad are combinations of the pro- whatcom- toxide of lead wnh the different acids. The peroxide pounds. is not knoyvn to combine with any acid: hence, strictly speaking, it is not a salifiable base. The following are the most important of these salts. Chlorate of I. Chlorate of Lead.—Former chemical name, Hyper- oxymuriate of Lead.—This salt may be formed by dissolv- ing the semi-vitrifnd oxide of lead (litharge) in chloric acid. The solution has a very syveet astringent taste. By spontaneous evaporation, it deposites the chlorate in bril- liant crystals. On burning coals, it emits a white smoke and the lead is revived. Hydrochloric acid forms a hydrochlorate and a subhydro- chlorate by combining with protoxide of lead. II. Hydrochlorate of Lead.—Usual chemical name, Mu- riate of Lead.—This salt may be formed by decomposing nitrate of lead by means of hydrochloric acid. It precipi- tates in the form of a white poyvder, which has a sweetish taste, and is soluble in twenty two parts of cold water. When dissolved in boiling water, it deposites, as the solu- tion cools, in crystals of a white colour, and brilliant ap- pearance like satin. These crystals are not altered by expo- sure to the air; but when heated, they melt and are converted into chloride of lead (horn lead). This salt is composed of Hvdrochloric acid 37—one atom. Protoxide of lead 112—one atom. Giving 149 for the number repre- senting the weight of its atom. III. Subhydrochlorate of Lead.—Usual chemical name, Submuriate of Lead.—This salt may be formed by treating, with water, a mixture of one part of semi-vitrified oxide of lead (litharge) and four parts of chloride of sodium (com- mon salt). This process constitutes one of the methods for obtaining; carbonate of soda from chloride of sodium (com- mon salt); and it has been described and explained under the head of carbonate of soda. Subhydrochlorate of lead is insoluble in water, and when neyvly formed has a white colour. After exposure to heat, by the action of which it becomes of a fine yellow colour, it is employed as a paint. Sulphate of IV. Sulphate qf Lead.—Sulphuric acid, when cold, has little action upon lead; but in a boiling heat, it oxidizes and lead SALTS OF OXIDIZED LEAD. 375 dissolves this metal, sulphurous acid being at the same Chap.iv. time emitted, and forms uith it a thick white mass, con-~" sisting of this sulphate. This salt, however, may be more readily formed by precipitating acetate of lead by the sul- phate of potash or of soda. It is a tasteless white powder. It occurs native in the form of crystals. It is composed of Sulphuric acid 40—one atom. Protoxide of lead 112—one atom. Giving 152 for the number repre- senting the weight of its atom. Nitric acid forms a nitrate and a subnitrate by combining Protoxide with protoxide of lead. of lead V. Nitrate of Lead.—This salt may be formed by dis- *S£* solving lead or its carbonate in nitric acid. It is in the form of crystals, which are opaque and white, and have a silvery lustre. It has a sweetish and harsh taste, and is not altered by exposure to air. It is soluble in water. When ex- posed to heat, it decrepitates, undergoes a kind of detona- tion, and emits brilliant sparks. It is composed of Nitric acid 54—one atom. Protoxide of lead 112—one atom. Giving 166 for the number repre- senting the weight of its atom. VI. Subnitrate of Lead.—This salt maybe obtained by boiling a solution of nitrate of lead upon protoxide of lead, and filtrating the liquid formed while hot; upon its cooling, the subnitrate is deposited in pearl-coloured crystals, yvhich have a sweet astringent taste. Ml. CARBONATE OF LEAD. (Common names, White Lead—Cerusse.) 1. This salt may be obtained by precipitating a solution Carbonate of lead in nitric acid, bv means of the carbonate of potash oflead;how or of soda. For the purposes of the arts, it is prepared by prepared exposing thin plates of lead, rolled spirally and placed on their edges, to hot vapours of common acetic acid (vinegar). The plates, after a certain time, become covered with a yvhite crust, which is scraped off. They are again and again exposed to the vapour of the acid, until they are en- tirely corroded. The yvhite substance thus formed is car- bonate of lead. The carbonic acid is probably formed by the decomposition of the acetic acid. 2. The carbonate of lead has been considered to be an oxide; and accordingly, the Edinburgh college calls it the white oxide of lead. It has also been called a subacetate of 376 SALTS. Book I. lead, on account of the manner in which it is prepared, it Division II. being by the action of common acetic acid (vinegar); but it is in fact a carbonate of lead, as was first ascertained by Bergman. 3. Carbonate of lead occurs native, sometimes in the form of crystals having a white colour and considerable lustre. Its specific gravity in this state is 7*23. 4. Carbonate of lead, when artificially formed, is a brittle, friable, heavy substance, insoluble in water, and possessing a snow-white colour and sweet taste. The beauty of its colour depends principally upon the purity of the lead from which it is manufactured. It has a scaly and foliated texture. 5. It is composed of Carbonic acid 22—one atom. Protoxide of lead 112—one atom. Giving 134 for the number represent- ing the weight of its atom. Used in the 6. Carbonate of lead is very much employed in the arts arts and m as a white paint. In pharmacy, it is used in the composition medicine r» of certain plasters and ointments, which are supposed to be efficacious as drying applications. Chromate VIII. Chromate of Lead.—When the solutions of nitrate of lead. Qf jea(j an(j cnromate of potash or of soda are mixed to- gether, this salt precipitates in the form of a powder. It con- stitutes a very important yellow pigment, under the name of chromic yellow. It is manufactured in the United States by decomposing the native chromate of iron, by means of potash, and precipitating the chromate of potash, thereby formed, by means of nitrate of lead. Chromate of lead occurs native under the name of the red lead ore of Siberia. In this state, it is in the form of crystals of a red colour, with a shade of yellow. Hydro- IX. Hydrofluate of Lead.—Usual chemical name, Fluate flnate. 0J Lead.—Hydrofluoric acid has no sensible action upon lead. Hence vessels of lead are generally used to contain this acid, instead of glass ones, yvhich are corroded by its action. This salt, hoyvever, may be formed by dropping hy- drofluoric acid into acetate of lead. It is in the form of brilliant plates, which are insoluble in water, but dissolve in nitric, hydrochloric and hydrofluoric acids. When heat- ed to redness, it melts, becomes yellow, and loses a portioa of its acid. SALTS OF OXIDIZED LEAD. 377 Acetic acid combines in two proportions yvith protoxide of Chap.iv. lead, and forms acetate and subacetate of lead. Protoxide X. ACETATE OF LEAD. fJSft** Syn. Sugar of Lead.—Sugar of Saturn.—Icetated Cerusse. acetates. 1. There are two processes for manufacturing acetate of l. Acetate lead. One consists in dissolving carbonate of lead, prepared ^^apdr;e. by exposing the metal to the fumes of vinegar, or the semi- pared. vitrified oxide of lead (litharge), in acetic acid, and evapo- rating the solution until it crystallizes. The other method is to immerse thin plates of lead in acetic acid; and as those which are nearest the surface become incrusted yvith a coat of oxide, to place them near the bottom, and thereby to bring other plates to the surface, to be incrusted in their turn. These plates also are transferred to the bottom; and by being changed in this manner every day, the whole at last become dissolved. The solution obtained is then crys- tallized by evaporation. 2. Acetate of lead is in the form of yvhite needle-shaped Its proper- crystals, which have a glossy appearance. It has a sweetUe8 and somewhat astringent taste. Its specific gravity is 2*345. It dissolves in rather less than four times its weight of cold water, and in a somewhat smaller proportion of boiling water. In the air, it undergoes no change. It is affected by the light; and when exposed to heat, its acid is entirely de- composed. It is composed of Acetic acid 51—one atom. Protoxide of lead 112—one atom. Giving 163 for the number represent- ing the weight of its atom. 3. This salt constitutes a very active article of the materia Uses in medica. It appears to exert a very powerful influence over medicine. hamorrhagies of the active kind. It acts in many alarming cases of this nature with wonderful promptitude. When the case is urgent and cannot admit of delay, the salt may be given in doses of from five to twenty grains, frequently repeated, or even in larger quantities. The danger of its exhibition, in large doses, appears to have been veryr much overrated. It is in very general use as an external applica- tion to abate inflammation. It is applied in solution by cloths or by means of crumbs of bread, or in substance, combined with cerate in the form of an ointment, formerly called saturnine ointment. XL SUBACETATE OF LEAD. 1. This salt may be formed by boiling together, in water, 100 2. Subace- parts of acetate of lead, and 150 parts of drv semi-vitrified ute°ne*d' oxide of lead (litharge), deprived of its carbonic acid. It is in 3 B 378 SALTS. Book I. the form of crystalline plates. It is not so sweet as the acetate, Division II. or so soluble in yvater. The preparation, formed by boiling acetic acid (distilled vinegar) upon semi-vitrified oxide of lead as long as the latter is dissolved, is a solution of sub- acetate of lead. It was first made by Goulard, a surgeon of Montpelier, and recommended by him as an excellent ap- plication in inflammation. It was formerly distinguished by the same the names of Goulard's extract, antl vinegar of lead; and hrd's ex- *s l^e same w*tn t*le 7Vater °f acetated litharge of the tract of London college. When formed into a cerate with yellow lead. wax anci olive oil, yvith the addition of a little camphor, it constitutes the preparation well known by the name of Goulard's cerate, the compound cerate of acetated litharge of the London college. Medical 2. Subacetate of lead had once considerable reputation as uses- an abater of inflammation; but, at the present day, it is not considered to possess any advantages over the solution of the simple acetate, as an application in such cases. List of salts Of the remaining salts of oxidized lead, there have been kaTomit^ more or less examined by chemists, the sulphite, selenate, ted. tellurate, nitrite, borate, phosphate, nitrophosphate, phos- phite, arseniate, molybdate, tungstate, antimoniate, antimo- nite, sulphocyanate, purpurate, gallate, formate, oxalate, sorbate, succinate, tartrate, potasso-tartrate, benzoate, sac- lactate, citrate, mellate, malate, lactate, suberate and zumate; but these salts are not of sufficient importance to be noticed. The rest of the salts of oxidized lead, amounting in number to 27, are unknown. General The salts of oxidized lead may be known by the follow- properties ing properties or marks. ofoxfdized *• A- considerable number of them are scarcely soluble in lead. water, without an excess of acid. Those which are soluble, form solutions, which are generally colourless and transpa- rent. 2. They have all, more or less, a sweet taste, accompanied yvith a degree of astringency. 3. Ferrocyanate (triple prussiate) of potash occasions a white precipitate in their solutions. 4. Hydrosulphate (hydrosulphuret) of potash occasions a black precipitate. sALTS OF OXIDIZED TIN. 379 Chap. IV. SECTION XXIII. SALTS OF OXIDIZED TIN. Salts of Oxidized Tin are combinations of the oxides Salts of ox- of tin with the different acids. Wized tin; what com- Hydrochloric acid forms a distinct salt with each of the 00x"J}fz8ed oxides of tin. tin forms I. Hydrochlorate of Tin—Usual chemical name, Muriate J™"*1*ro qf Tin.—When tin is dissolved in four times its weight of chloric ^ hydrochloric acid, the brownish-yellow solution formedaci(L yields, upon evaporation, this salt in needle-shaped crys- chiorateof tals, which are soluble in water, and somewhat deliquescent t"». in the air. When treated yvith water, it is converted into a subsalt which precipitates, and a supersalt which remains in solution. When evaporated to dryness and afterwards fused in close vessels, water becomes formed, and the salt is con- verted into protochloride of tin. II. Perhydrochlorate of Tin.—-Usual chemical name, 2. Perhy- Permuriate of Tin.—The hydrochlorate is very liable todrochl°- be converted into this salt. It abstracts an atom of oxygen rate" from a great number of bodies containing this supporter, and thereby has its protoxide converted into peroxide. This change is produced by the contact of air, and by the addition of nitric acid. It is effected also by arsenious and arsenic acid, which become reduced to the metallic state. When molybdic or tungstic acid is dropped into a solution of the simple hydrochlorate, the former becomes converted into molybdous acid, and the latter, into oxide of tungsten. The persalts of oxidized iron and of copper are reduced to protosalts, by being added to the same solution; while, under the same circumstances, antimonious acid, the oxide of zinc and silver, and the peroxide of mercury and man- ganese, are reduced to the metallic state. In all the chemical changes just enumerated, there is formed a perhydrochlorate of tin. This salt is an important agent in the production of the scarlet dye. When concen- trated, and distilled yvith sulphuric acid by means of a gentle heat, it is converted into perchloride of tin (fuming liquor of Libavius). Sulphuric acid forms a distinct salt yvith each of the oxides Oxidized of tin. tin forma III. Sulphate of Tin.—This salt may be formed bySSiTuF pouring sulphuric acid into hydrochlorate of tin. It is in phuric acid. the form of a yvhite poyvder, yvhich may be crystallized by solution and evaporation. 380 SALTS. dmSo h IV#- PersulPhate °f T*n___Sulphuric acid, when cold, lias v""on ' very little action on tin; but when assisted by heat, it first peroxidizes this metal, and then dissolves it. The solution obtained cannot be made to crystallize; but when evaporat- ed, it assumes the form of a gelatinous mass, which deposites a white powder when treated with water. Oxidized Nitric acid forms one salt with protoxide of tin, and one tin. enters ,. • , • , r • i into two ni- salt w,tn peroxide of tin and ammonia. trates. V. Nitrate of Tin.—Nitric acid acts with great energy upon tin; a great deal of heat is evolved, and the metal becomes oxidized. When nitric acid, of the specific gravity of 1*114, is poured upon tin, a yellow coloured solution is obtained consisting of this salt. If water be added to this solution, the salt becomes decomposed, and protoxide of tin precipitates in the form of a povrder. During the solu- tion of the tin, a quantity of ammonia is formed. From this fact, it is evident, that both yvater and the acid are de- coi' posed, and yield oxygen to oxidize the tin; while the hydrogen of the former, by combining with the azote of the latter, forms ammonia. The ammonia may be made sensible by its odour, upon the addition of potash to the solution. VI. Ammonio-pernitrate of Tin.—When nitric acid, of the specific gravity of 1*25, is poured upon tin, a violent action takes place, the metal becomes peroxidized, but does not dissolve. Hence there is no pernitrate of tin. But a quantity of ammonia becomes formed, in the manner just explained, which is capable of combining with nitric acid and peroxide of tin, so as to form the triple salt here noticed. Whenever nitric acid appears to dissolve the peroxide of tin, it is by the assistance of ammonia, and the result is the formation of this triple salt. fluate^0* VI1' per hydrofluate of Tin.—Usual chemicalname, Fluate of Tin.—Hydrofluoric acid does not act upon metallic tin. This salt, however, may be formed by dissolving peroxide of tin in hydrofluoric acid. The solution, by evaporation, becomes opaque from the precipitation of the salt, which may be again dissolved by the addition of water. List of salts Qf the remaining salts of oxidized tin, there have been of oxidized , .°ii , • i ii-ii i tin omitted, more or less examined by chemists, the sulphite, hydrosul- phate, selenate, borate, phosphate, arseniate, sulphocyanate, purpurate, oxalate, succinate, acetate, tartrate, potasso-tar- trate, benzoate and zumate; but these salts are of too little importance to be noticed. The rest of the salts of oxidized tin, amounting to 43, are unknown. SALTS OF OXIDIZED COPPER. 381 The salts of oxidized tin may be known by the following Chap. iv. properties or marks. General 1. They are generally soluble in water, and their solutions properties have usually a yellowish or brownish tinge. Sometimes, rf£^d£l5j however, they are colourless. tin. 2. Ferrocyanate (triple prussiate) of potash occasions a white precipitate when dropped into their solutions. 3 Hydrosulphate (hydrosulphuret) of potash occasions a brownish-black precipitate in solutions of the protosalts, and a golden yellow precipitate in solutions of the per- salts. SECTION XXIV. SALTS OF OXIDIZED COPPER. Salts of Oxidized Copper are combinations of the per- Salts of oxi- oxide of copper with the different acids. The protoxide dizedcop- of copper is not known to enter into the composition of com-™ any salt as a base. Hence all the salts to be enumerated pounds. in this section are persalts. The following are the most important of them. I. Perchlorate of Copper.—Former chemical name, Hy- Perchlo- peroxymuriate of Copper.—This salt may be formed byrateofcoP" dissolving peroxide of copper in chloric acid. It has a green colour. When exposed to heat, it fuses and gives out a green light. It cannot be crystallized without difficulty. II. Perhydrochlorate of Copper.—Usual chemical name, Perhydro- Muriate of Copper.—This salt may be formed by dissolving chlorate' copper in hydrochloric acid assisted by heat, or its per- oxide in the cold acid. The solution has a fine green colour, and may be made to yield crystals by concentration. This salt has a fine grass-green colour, and an exceedingly acrid and caustic taste. It is very soluble in water. By ex- posure to air, it attracts moisture, and is converted into an oil-like liquid. When evaporated to dryness, at a tempera- ture not exceeding 400°, it is converted into perchloride of copper. If the heat be further increased, a portion of chlorine is driven off, and the perchloride becomes convert- ed into a protochloride. The compound, first formed by Proust, and heretofore considered a simple hydrochlorate (muriate) of copper, turns out, upon further examination, to be a protochloride of copper. 382 SALTS. Book I Sulphuric acid forms three salts with peroxide of copper. Division H. ~nA *.«« -™l*„ ...:.u______j_ _r______ • rr ' and two salts with peroxide of copper and ammonia. Peroxide of copper en- HI. BIPERSULPHATE OF COPPER. ters into rn „ five sul- (.Common names, Vitriolated Copper—Blue Vitriol.) phat.es. L This salt is very seldom formed by the direct combi- suipiiate of nat'0n °f its constituents. It is manufactured, in the large copper. way, by evaporating and crystallizing mineral waters, con- taining the salt in solution; or by burning the native sul- phuret of copper, or moistening it with water, and exposing it to the air. When formed by the latter methods, the sul- phur becomes acidified, and the copper, oxidized; and, by their combination thus altered, they form the salt in question. Properties. 2. Bipersulphate of copper is in the form of crystals, which have a deep blue colour, and a strong, styptic, me- tallic taste. It changes vegetable blues to red. Its specific gravity is 2*19. It is soluble in about four parts of cold water, and in one and a half parts of boiling water. When exposed to the air, it undergoes a slight efflorescence, and its surface becomes covered with a greenish-white powder. When heated, it loses its water of crystallization, which amounts to about 36 per cent, and becomes converted into a bluish-white powder. In a pretty strong heat, its acid is entirely driven off, and peroxide of copper remains behind. 3. It is composed of Sulphuric acid 80—.two atoms. Peroxide of copper 80—one atom. . . 160 Hence it is evidently a bipersulphate. Usesinme- 4. Bipersulphate of copper, even in small doses, proves ,cine' powerfully and promptly emetic. But its internal use, oyv- ing to its activity, is not safe; and accordingly, it is not much employed. Externally, it is used, as an escharotic, to destroy warts and fungous excrescences; and as a stimu- lating application to indolent and ill-conditioned ulcers. 2. Persul- IV. Persulphate of Copper.—This salt resembles very p a e' much the one last described. It is formed by saturating the extra atom of acid, contained in the bipersulphate, yvith peroxide of copper. x Subper- y. Subpersulphate of Copper.—When a solution of pure potash is poured into a solution of the persulphate of cop- per, the potash abstracts a portion of sulphuric acid from the persulphate, and this salt appears in the form of a green powder, which swims on the surface of the solution. i. Ammo- VI. Ammonio-persulphate of Copper—This salt has been phaFe"111 f°rmed Dy Berzelius. It is a compound of one atom of sulphate of ammonia, and one atom of persulphate of copper. SALTS OF OXmiZED COPPER. 383 VII. AMMONIO SUBPERSULPHATE OF COPPER. ihap.iv. (Formerly called, Ammoniacal Copper.) 1. This triple salt may be formed by pouring ammonia 5. Ammo- into a solution of bipersulphate of copper (blue vitriol), and JjJJj[iE?r" afterwards adding alcohol (pure spirit of wine) to the blue liquid obtained. The alcohol has a stronger affinity for water than the triple salt has, which is in solution; hence the latter separates in the form of blue silky crystals. 2. It is prepared, by the apothecaries, by rubbing together, in a mortar, until all effervescence ceases, a mixture of bi- persulphate of copper (blue vitriol) and carbonate of am- monia. The mixture becomes moist, in consequence of the triple salt formed containing less water of crystallization than its constituents in a separate state. It is then dried and preserved in well stopt vials. As it is liable to partial decomposition during its exsiccation, it is much preferable to prepare the salt by the method given in the foregoing paragraph. 3. This salt has been used in the treatment of epilepsy. Medical But its doubtful efficacy, and the disagreeable effects, which uses- it sometimes produces, have been the cause of its being in a great measure laid aside. The dose is about half a grain, exhibited twice a-day, and gradually increased. Nitric acid combines in two proportions with peroxide of Peroxide of copper, and forms pernitrate and subpernitrate of copper. *°PPer VIII. Pernitrate of Copper.—This salt may be formed salts with by dissolving copper in nitric acid, and slowly evaporating nitric aci«*; the solution until it crystallizes. The solution is attended with effervescence, owing to the emission of deutoxide of azote (nitrous gas). This salt is in the form of crystals, which have a fine blue colour, and an acrid and metallic taste. It is exceedingly caustic, and acts upon the skin yvith great energy. It is very soluble in water, and deliquescent in the air. At a heat, not exceeding 100°, it undergoes the watery fusion; and, if the temperature be increased, loses its water, and ultimately a part of its acid. It acts yvith great energy upon tin; and if a portion of it be moistened with water and wrapt up in a sheet of tinfoil, a strong heat is produced, a quantity of deutoxide of azote is quickly form- ed, and the tinfoil bursts open and in many cases catches fire. It is composed of Nitric acid 54—one atom. Peroxide of copper 80—one atom. 134 IX. Subpernitrate of Copper.—When a solution of potash is poured into a solution of pernitrate of copper, but not 384 SALTS. Book I. in sufficient quantity to decompose the dissolved salt com- Dl-islon II. pletely, part of its acid is abstracted, and a supernitrate ap- ~" pears in the form of a precipitate, which is at first blue, but becomts green by agitation. Percarbo- X. Percarbonate qf Copper.—This salt may be formed by J^ofcop" precipitating a solution of pernitrate of copper, by a solution of carbonate of potash or of soda. It has a fine apple-green colour. It occurs native under the various names of mala- chite, blue copper ore, and anhydrous carbonate, according as it is modified by the presence or absence of yvater. XI. Perarseniate of Cobper.—Several varieties of this salt have been found in the copper mines of Cornwall in England. Perarsenite XII. Perarsenite of Copper—Scheele's Green—This salt of copper^ may be obtained bv the following process: Form two so- orSdieele's lution3. Qne by dis'solving two parts of bipersulphate of copper (blue vitriol) in forty-four parts of water; and the other by dissolving, in the same quantity of water with the assistance of heat, two parts of common carbonate of potash (potash of commerce) and one part of arsenious acid (white oxide of arsenic). The latter solution will con- tain an arsenite of potash. Add gradually the solution of the bipersulphate, while hot, to the solution of the arsenite, stirring the whole frequently. The mixture upon standing, gradually deposites a fine green powder, which, after being well washed and dried, constitutes the perarsenite of copper. XIII. Perkydrofluate of Copper.—Hydrofluoric acid does not act upon copper. This salt, however, may be formed by dissolving peroxide of copper in an excess of hydrofluoric acid. The solution, upon evaporation, deposites the salt in the form of small blue cry stals. XIV. PERACETATE OF COPPER. Peracetate 1. Acetic acid acts upon copper very slowly in open of copper, vessels, and exerts no action upon it in close ones. This how obtain- sal^ however? may be readily formed by dissolving per- oxide of copper in acetic acid. Verdieris- 2- Verdigris of commerce appears to be a mixture of an impure peracetate and subperacetate of copper. But its composition peracetate. is not invariable; and it very frequently contains a pretty Preparation large proportion of percarbonate of copper. Verdigris is of verdigris. coinmonly prepared by exposing plates of copper to the fumes-of vinegar. In France, it is usually made bv strati- fying, in earthen pots, plates of .copper with vine-stalks; the latter having previously undergone the acetous fermenta- tion by being immersed in wine for a sufficient time. After the metallic plates have remained in this situation for from SALTS OF OXIDIZED COPPER, 385 ten to twenty days, they are taken out of the earthen pots, Chap. iv. and placed on their edges in cellars, with their surfaces in contact; and during the course of seven or eight days, they are alternately dipped in water, and allowed to dry, for six or eight times during each day. They are then found to have swelled, and to be every where covered yvith a coat of verdigris. The verdigris may be easily scraped off with a knife, and is now in the state of a paste. It is afterwards beaten well with wooden mallets, and then packed in bags of white leather, in which it is dried by exposure to the air and sun. Verdigris, when good, is of a bluish-green colour, Its proper- difficult to break, and free from black or white spots; itties* should not be deliquescent nor have a salt taste. 3. Peracetate of copper, when pure, is in the form of Properties crystals of a bluish-green colour. Its taste is disagreeably oflhe i'ure mt tallic. It is but sparingly soluble in water. In the air, it suffers efflorescence. It is frequently used in dyeing. The impure peracetate (verdigris) is very much employed in the formation of green paints. 4. Verdigris is very seldom used internally as a medicine; Uses in me- and yvhen so employed, it acts as an emetic. Its externald,cme- use is much more common. Dissolved in vinegar and after- wards mixed with honey, it forms the oxymel of verdigris, which is sometimes used to cleanse ulcers, more especi- ally such as are venereal and are situated in the mouth and throat. But its use for the latter purpose is not convenient; as part of the preparation is liable to pass into the stomach, and thereby produce unpleasant consequences. When mix- ed with some mild ointment, it forms a gently escharotic application, which is well suited to particular states of ex- ternal ulcers. Of the remaining salts of oxidized copper, there have Salts of ox, been more or less examined by chemists, the potasso-sul-"l,Zt:<, C?P" ,. il- i i • i n per. omit- phate, sulphite, potasso-sulphite, selenate, tellurate, nitrate, ted. borate, phosphate, chromate, molybdate, tungstate, anti- moniate, antimonite, sulphocyanate, purpurate, formate, oxalate, ammonio-oxalate, potasso-oxalate, soda-oxalate, sorbate, succinate, tartrate, potasso-tartrate, benzoate, sac- lactate, citrate, mellate, lactate, suberate and zumate; but these salts are of too little importance to be noticed. The rest of the salts cf oxidized copper, amounting to 29, are unknown. The salts of oxidized copper may be distinguished by Their gen- the following properties or marks. erai_pro- 1. They are almost all soluble in water, and their solu- pe' tions are either blue or green. 3 C 386 SALTS. Book I. 2. Their solutions are changed to a deep-blue colour by DiTi8ionlt the addition of ammonia. 3. Ferrocyanate (triple prussiate) of potash occasions a red precipitate when poured into their solutions. 4. Hydrosulphate (hydrosulphuret) of potash occasions a black precipitate. 5. A plate of polished iron, by being plunged into their solutions, becomes covered with a coat ot metallic copper. SECTION XXV. SALTS OF OXIDIZED BISMUTH. Salts of oxi-Salts of Oxidized Bismuth are combinations of the dizedbis- oxide of bismuth with the different acids. Only four of mutn; what , , . , , , , J compounds, these salts will be described. Hydrochlo- I. Hydrochlorate of Bismuth.—'Usual chemical name, muth! S Muriate of Bismuth.—Hydrochloric acid, while cold, has scarcely any action upon bismuth; but when mixed with nitric acid, it is capable of dissolving the metal. The solution formed, upon evaporation, yields this salt in small crystals. II. Sulphate of Bismuth.—-Sulphuric acid acts upon bis- muth by the assistance of heat, and converts the metal into a white powder. The sulphate formed, when treated yvith water, is divided into a supersulphate and a subsulphate of bismuth. Nitric acid combines in two proportions with the oxide of bismuth, and forms nitrate and subnitrate of bismuth. III. Nitrate of Bismuth.—Nitric acid, when concentrated, acts with great violence upon bismuth, and converts it into a white poyvder. When diluted, it converts the metal into the same white powder, which becomes dissolved as soon as formed. This salt is deposited, from the solution, in the form of white crystals, which, upon exposure to air, at- tract a little moisture, and become covered with a white crust of hydrated oxide. On burning coals, they detonate feebly, and a yellow powder remains behind, not easily redu- ced to the metallic state. IV. SUBNITRATE OF BISMUTH. (Formerly called, Magistery of Bismuth.) 1. When the nitrate of bismuth in crystals, or the nitric solution of bismuth is treated with water, this liquid ab- stracts a portion of acid from the neutral salt, and a sub- nitrate of bismuth precipitates in the form of a white pow- Oxidized bismuth forms two salts with nitric acid. 1. Nitrate. 2. Subni- trate. SALTS OP OXIDIZED MERCURY. 387 der. When the nitric solution is treated with chloride of Chap iv. sodium (common salt), or bitartrate of potash (cream of ** tartar), a subnitrate also appears to be formed. When thus prepared, it constitutes the paint, called pearl or flake white, which is sometimes used to give the skin a beautiful white colour* 2. Of late years, the subnitrate of bismuth has been intro- Used in duced into practice, and, from the experience already had ""^m5"^- of it, appears to be well entitled to the attention of physi- cians. Its medical properties are those of a tonic and anti- spasmodic. In several deranged states of the stomach, as shown in violent pain or spasms in this organ, and in some cases of dyspepsia, it has been found, in the hands of several distinguished practitioners both in Europe and America, a very valuble remedy. Its medium dose is about two grains, given twice or thrice a-day. In severe cases, it may be given in doses of five grains. Of the remaining salts of oxidized bismuth, there have Saiu of oxl- been noticed by chemists, the sulphite, carbonate, borate, diz!u b""-* ,, J . 111,1 i muth, omit* phosphate, arseniate, molybdate, sulphocyanate, oxalate, ted. succinate, acetate, tartrate, and benzoate; but these salts are not of sufficient importance to be described. The rest of the salts of oxidized bismuth, amounting to 48, are un- known. The salts of oxidized bismuth may be recognised by the Their gea- following properties or marks. t.rrtiPr0 1. Their solutions in acids are usually colourless; but when water is added to them, a white precipitate makes its appearance. 2. Ferrocyanate (triple prussiate) of potash occasions in their solutions, a white precipitate, sometimes with a shade of yellow. 3. Hydrosulphate (hydrosulphuret) of potash occasions a dark-brown precipitate. SECTION XXVI. SALTS OF OXIDIZED MERCURY. Salts of Oxidized Mercury are combinations of the Salts of ox- oxides of mercury with the different acids. The follow-idized "P61"" ing are the most important of these salts. impounds. Chloric acid forms a distinct salt with each of the oxides mercury of mercury. 388 SALTS. Book I. I. Chlorate of Mercury.—When chloric acid is poured Division II. UpQn protoxide ot mercury, the latter becomes dissolved; forms two and, as the solution proceeds, this salt precipitates in the salts^'ith form of yelloyvish grains. It is but sparingly soluble in acid! water, and has a metallic taste. When heated, it detonates and gives out oxvgen, being converted into perchloride of mercury (corrosive sublimate). II. Perchlorate of Mercury.—Former chemical nnme, Hy peroxymuriate of Mercury.—This salt may be formed by dissolving peroxide of mercury in chloric acid. It always contains an excess of acid. It is pretty soluble in yvater, and has a strong taste, resemhlinp; that of perchloride of mercury (corrosive sublimate). When heated in a glass tube, it yields a considerable quantity of oxygen; antl a yellow matter remains behind, which appears to be a mix- ture of peroxide of mercury, and the two chlorides of this metal (calo nel and corrosive sublimate). Hydrochlo- HI. Hydrochlorate of Mercury—Hydrochloric (muria- ™I?..?,L tic) acid does not appear capable of combining with the does not oxides of mercury. When the attempt is made to produce exist. thjs union, a double decomposition takes place; the hydro- gen of the acid combines with the oxygen of the oxide, and forms water; while the chlorine ot the former unites with the metallic mercury, and forms a chloride. The compounds, formerly considered to be muriates (hydro- chlorafs), under the names of calomel and corrosive sublimate, are now found to be chlorides of mercury. They have been already described under the head of mercury. Oxidized Sulphuric acid combines in two proportions with protoxide mercury Qf mercury, and forms sulphate and supersulphate of saiuwith" mercurv; and in two proportions also with the peroxide, sulphuric forming persulphate and superpersulphate of mercury. acid. The galt of each oxiciei with excess of acid, will be des- cribed before the neutral salt. l. Super- IV. Supersulphate of Mercury.—When sulphuric acid is sulphate of b0,led upon mercury, and the process stopped before the mercury. whole of the acid jg ^r\vtn off by evaporation, this salt is obtained in the form of a white mass, capable of reddening vegetable blues, possessing an acrid tast--, and of different degrees of solubility, according to the proportional excess of acid which it may contain. 2. Sulphate. V. Sulphate of Mercury.—This salt may be obtained by repeatedly washing the salt, last described, in small por- tions of yvater. The excess of acid, which it contains, is thereby separated, and it becomes reduced to the neutral state. It may be formed also by boiling sulphuric acid, diluted with its own weight of water, upon mercury. A SALTS OF OXIDIZED MERCURY. "$89 solution is formed, which, by proper evaporation, may be Chap.IV. made to yield the salt in white crystals. It is not altered by exposure to air, but becomes decomposed by heat. It is soluble, without decomposition, in 500 parts of cold yvater, and in about 287 parts of boiling water. VI. Superpersulphate of Mercury.—U \he process by which 3. Super- the supersulphate is formed be not discontinued while there pn^"1" yet remains an excess of acid, but the heat be kept up; part of the acid in excess is gradually decomposed, (sulphurous acid being disengaged), the protoxide of mercury combines with an additional atom of oxygen, and there results a salt, containing the peroxide with excess of acid. This salt appears to vary in the proportional excess of acid, which it may contain. When obtained at once in the form of a dry mass, it has a fine white colour, and is somewhat deliques- cent. It contains considerably more than one atom of acid, united to an atom of bast. VII. PERSULPHATE OF MERCURY. {Yellow Subsulphate of Mercury, of the Edinburgh college—Formerly called Turpeth Mineral.) 1. When the salt last described is treated yvith water, the 4. Persul- excess of acid w hich it contains is washed off, and a neutral Phate» or persulphate remains behind. mineral. 2. This salt is directed by the Edinburgh college to be Prepara- prepared by boiling, to dryness, three parts of sulphuric utealus™6 acid upon two parts of mercury; and throwing the white mass formed, previously pulverized, into boiling water. A poyvder immediately appears, which consists of the salt in question. 3. It is generally supposed, that the treatment of the su- perpersulphate of mercury yvith water, separates this salt into a supersalt remaining in solution, and a subsalt, which precipitates; and consequently that the turpeth mineral is a salt with excess of base. But it has been correctly as- certained, that the salt, from wh;ch the turpeth mineral is precipitated, is already a supersalt; and that the effect of the treatment with water is merely to wash off the excess of acid, which it contains; whereby it becomes converted to the state of a neutral salt, which, being insoluble, appears in the form of a precipitate. 4. Persulphate of mercury, or turpeth mineral, has a its proper- bright yelloyv colour, and a somewhat acrid taste. It isties- soluble in 2000 parts of cold water, and in 600 parts of boiling yvater. Its specific gravity is 6*44. It is composed of Sulphuric acid 40—one atom. Peroxide of mercury 216—one atom. 256 390 SALTS. Book i. 5. This salt constitutes a very active article of the materia Division H. medica, and is too much neglected by practitioners in the Forms an United States. Its most prominent virtue is its strong diciue.me emetic property; which, considered in connection yvith its mercurial nature, would naturally lead, a priori, to the be- lief, that it is a preparation of great activity. When exhibit- ed with a view to its emetic effect, it occasionally produces a salivation, unless this event is guarded against by the use of purgatives. It is said to be useful in swellings of the tes- ticle from a venereal cause, and may be presumed, in such cases, to act both by its emetic and antisyphilitic powers. It has been employed also, with success, in inveterate dis- eases of the skin, and in obstinate glandular obstructions. When mixed with the powder of liquorice root, snuff, or some similar substance, it forms a very convenient errhine. In small doses of one or tyvo grains, it acts as an alterative. Its dose, when exhibited with a view to its emetic property, is from two to eight grains. v Oxidized Nitric acid is capable of combining with protoxide of mer- entersmto curY» with protoxide of mercury and ammonia, or with three ni- peroxide of mercury; and, in each combination, forms a trates. distinct salt. l. Nitrate VIII. Nitrate of Mercury.—Nitric acid, without the of mercury. assistance of heat, is capable of dissolving very nearly its own weight of mercury; an effervescence takes place, owing to the emission of deutoxide of azote (nitrous gas), and the metal becomes protoxidized. The solution obtained is colourless, very heavy, and exceedingly caustic. It tinges the skin and almost all animal substances, of an indelible black colour. When treated with water, it does not separate into a supersalt and a subsalt. By spontaneous evaporation, it yields transparent crystals of the nitrate. When this salt is placed upon burning coals, it detonates feebly, emitting a lively white flame. When mixed with a little phosphorus, and struck with a hot hammer, a violent detonation takes place, and the mercury is revived. IX SUBNITRATE OF MERCURY-AND-AMMONIA. {Ash-coloured Oxide of Mercury of the Edinburgh college.) * Ammo- *• This salt is ordered to be prepared by the Edinburgh iio-subni- college by the following process: Dissolve four parts of trate. mercury in five parts of diluted nitrous acid; then gra- dually add fifteen parts of water. To the mixture, thus formed, add yvater of carbonate of ammonia as long as any precipitate appears. The precipitate, after being separated, yvashed and dried, constitutes the triple salt in question. 2. This salt is misnamed an oxide by the Edinburgh SALTS OF OXroiZED MERCURY. 391 college. The solution of mercury, in the nitrous acid of the Chap.iv. colleges, forms, in fact, a solution of nitrate of mercury; for-------- their nitrous acid is nitric acid holding deutoxide of azote (nitrous gas) in solution. The addition of the water of car- bonate of ammonia throws down a subnitrate, combined with a portion of ammonia. 3. Subnitrate of mercury-and-ammonia, prepared by the Properties. process just given, is a grey powder. It does not appear perfectly homogeneous. Acetic acid is capable of dissolving a portion of it, consisting perhaps of protoxide of mercury. The white powder, which remains behind, may be consi- der! d as the pure subnitrate. 4. This preparation is used, as a substitute for the protox- Usesinme- ide of mercury prepared by trituration, to form a mercurialmcine- ointment; and although much more easily prepared than the oxide, it does not appear to be often employed. X. PERNITRATE OF MERCURY. 1. When nitric acid is made to act upon mercury by the 3. Pemi- assistance of heat, a large quantity of deutoxide of azote trate- (nitrous gas) is emitted, and the metal becomes peroxidized and converted into a yellow crystalline mass, constituting this nitrate. This salt is acrid and corrosive. When in solu- tion and treated with cold water, it is divided into a super- salt which remains in solution, and a subsalt which precipi- tates in the form of a white powder. If the water with which the salt is treated be hot, the same division of it takes place; but the precipitated portion, instead of being white, is greenish-yellow. 2. Pernitrate of mercury, prepared in a certain way with Forms yel- hog's lard, forms the valuable ointment, called yellow, or,ow flinV. citron-coloured ointment. The following is the method pur- hog"! lard! sued by the colleges. [l.] Dissolve one part of mercury in two parts of nitrous acid of the shops by digestion in a sand heat. While the solution, thus formed, is quite hot, add twelve parts of hog's lard, previously melted by itself, and just beginning to grow stiff. The lard must then be mixed intimately with the nitric solution, so as to form an ointment. What is called the milder yellow ointment is prepared in the same manner, there being three times the quantity of hog's lard employed. [2.] The yellow ointment is an active preparation of mer- Medical cury, well suited as an application to herpes, tinea capitis, uses °»yei- and similar obstinate cutaneous affections. It is also narti- low .oint" cularly efficacious in venereal blotches, and ulcerations. Its chief inconvenience, as an ointment, is its tendency to be- come hard and pulverulent; which is owing to the excess of acid used in its preparation. This objection may be ob- 392 SALTS. Rook I. viated by preparing the ointment, by mixing with hog's Division 11. }ar(i the subpernitrate of mercury, which is precipitated from the solution of the pernitrate by the addition ol hot water. When thus formed, it continues perfectly solt, even for six months. Carbonate XI. Carbonate of Mercury.—Carbonic acid does not act of mercury. UpQn mercury; but when a carbonate of potash or of soda is dropped into a solution of nitrate of mercury, this salt ap- pears in the form of a white precipitate. XII PERPHOSPHATE OF MERCURY. Perphos- i. This salt may be formed most conveniently by mixing *iate' together solutions of phosphate of soda, and pernitrate of mercury. A double decomposition takes place, and per- phosphate of mercury becomes precipitated. How pre- 2. It is directed to be prepared by the dispensatories in pared for the following manner. Calcined bones (phosphate of lime) use. are decomposed by means of diluted sulphuric acid; and, after all the sulphate of lime (gypsum) formed is separated, the remaining superphosphate is saturated with pure potash. The liquid thus obtained, by evaporation, yields crystals of phosphate of potash. This salt is then dissolved in water, and decomposed by a solution of pernitrate of mercury. A precipitate immediately appears, which must be completely washed v\ith warm water, and slowly dried; it is now pure perphosphate of mercury. What remains in solution, after the precipitate is separated, is nitrate of potash (nitre). Properties. 3. Perphosphate of mercury is in the form of a white powder. Its specific gravity is 4'98. When rubbed in the dark, it phosphoresces. By distillation, it may be made to yield phosphorus. Medical 4. This salt has of late years been introduced into the uses. practice of medicine. It has the usual properties of the mercurial preparations for internal use, but is far more ac- tive. It must, therefore, be exhibited with great caution, and in small doses. Even in doses not exceeding half a grain, it has produced violent vomiting and ptyalism. It is said to be preferable to all other preparations of mercury, in certain cases of the venereal disease, occurring in patients of torpid and insensible fibres. It is also said to have been found useful in exostosis, in obstructions of the lymphatic system, and in chronic complaints of the skin. XIII. Hydrofluate of Mercury.—Hydrofluoric (fluoric) acid does not act upon mercury; but, by the assistance ot heat, it is capable of dissolving its peroxide. The solution, by evaporation, deposites this salt in small yellow crystals. It always contains an excess of acid. By repeated affu?ions, SALTS OF OXIDIZED MERCURY. 393 nearly all the acid may be washed away, leaving scarcely Chap iv. any thing behind but the peroxide. XIV. Hydrocyanate of Mercury.—This salt does not ex- Hydrocya- ist. When peroxide of mercury is heated in hydrocyanic acid natl of •i 11 u u • i i mercury vapour, a violent action takes place; much heat is evolved, does not and the compound is destroyed. When the same acid vapour exist is brought in contact with the peroxide, it becomes absorb- ed; and a compound is formed, which, by being heated, gives out water in a state of vapour, and is converted into the substance usually called prussiate of mercury. This substance, however, is in reality a cyanodide of mercury; since the water which appears is evidently the result of a mutual decomposition between the acid vapour and the peroxide. Now a similar decomposition is supposed to occur, yvhenever the attempt is made to form a hydro- cyanate. Hence, therefore, the compounds, usually called prussiates, are in fact cyanodides. Acetic acid forms a distinct salt with each of the oxides of Oxidized mercury. mercury XV. ACETATE OF MERCURY. saltTwith° 1. This salt may be prepared by mixing together the so- acetic dM- lutions of. nitrate of mercury and acetate of potash, and 0fni^cury setting the mixture aside to crystallize. In this case, a double decomposition takes place, which results in the for- mation, of acetate of mercury and nitrate of potash. The former being much less soluble than the latter, enables the operator to separate it by crystallization. 2. Acetate of mercury is in the form of crystals, possess- ing a silver-yvhite colour, and an acrid taste. It is but spa- ringly soluble in cold yvater, but dissolves readily in boiling water. 3. This acetate is sometimes employed in medicine, and Used some has a place in the dispensatories. It is highly probable, thattim" .,n it claims no superiority over the preparations of mercury in common use. XVI. Peracetate of Mercury.—When peroxide of mer-2. Perace- cury is treated with acetic acid, it is dissolved; and thetate- solution, when evaporated to dryness, forms a yellow deli- quescent mass, which, yvhen treated with water, divides into a supersalt remaining in solution, and a subsalt, which pre- cipitates. Of the remaining salts of oxidized mercury, there have sa'ts of been more or less examined by chemists, the hy drosulphate, oxidized selenate, borate, arseniate, chromate, molybdate, tungstate,omittedT' sulphocyanate, purpurate, oxalate, succinate, tartrate, po- 3 D 394 SALTS. perties. Book I. tasso-tartrate, benzoate, saclactate, citrate, mellate, malate, Division II. lactate and zumate; but these salts are of too little im- portance to be noticed. The rest of the salts of oxidized mercury, amounting in number to 37, are unknown. Their ge- The salts of oxidized mercury may be distinguished by "p'hIF1'0" l^e follow'ng properties or marks. 1. When strongly heated, they are generally volatilized. 2. Ferrocyanate of potash, dropped into their solutions, occasions a whitish precipitate, which becomes yellow upon exposure to the air. 3. Hydrosulphate (hydrosulphuret) of potash occasions a black precipitate. 4. When a plate of copper is placed in their solutions, the mercury is revived. SECTION XXVII. SALTS OF OXIDIZED SILVER. Salts of oxi- Salts of Oxidized Silver are combinations of the oxide dized sil- of silver with the different acids. The following are the ^mp'ound, most important of these compounds. Chlorate of I. Chlorate of Silver.—Former chemical name, Hyper- Sive°r oxymuriate of Silver.-T\Cis salt may be formed by dissolv- ing oxide of silver in chloric acid. It is in the form of opaque crystals, which are soluble in water. Hydrochlo- IL Hydrochlorate of Silver does not exist. When the SeofT attempt is made to form this salt, water and chloride of verdon silver (horn silver) become formed. This chloride was not exist. ^rerl^called mu4te of silver, from a wrong notion of i^n:t^7^t0.-When the solutions of nitrate of silver and iodate of potash are mixed together, a double de- ^osftlon takes place, and this salt falls in the form of a VY\Tsuiphate ofSilver.-SulPhuric acid, while cold does not act up{n silver; but in a boiling temperature, it attacks -hi. metal when reduced to the state of powder, the action ^ nK a t nded by the extrication of sulphurous acid gas, and inverts it inl a white mass soluble m diluted sulphu- ric acid. This solution is colourless and yieUIs upon eva poration, the salt in question m the form of bnUiant white crystals. This salt is but sparingly soluble in water. It dis solves in nitric acid without decomposition. When heated, SALTS OF OXIDIZED SILVER. 395 it first melts, and afterwards is decomposed into silver, sul- Chap.iv. phurous acid and oxygen gas. V. NITRATE OF SILVER. (Common name, Lunar Caustic.) 1. Nitric acid acts readily upon silver, and dissolves Nitrate of about half its weip-ht of this metal. The solution is attended filver» or li_n.tr Ccius*" by effervescence, owing to the disengagement of deutoxide tic. of azote (nitrous gas). The nitric acid ought to be perfectly pure. If it contain hydrochloric (muriatic) acid, as the ni- tric acid of commerce always does, then a chloride of silver (horn silver) appears in the form of a white insoluble pow- der. It is by means of a solution of nitrate of silver, that manufacturers of nitric acid are enabled to separate any hydrochloric acid, with which their acid may be mixed. The nitric solution of silver is colourless, and exceedingly heavy and caustic. When evaporated until a pellicle begins to form on its surface, nitrate of silver is deposited in the form of brilliant crystals. 2. The colleges direct this salt to be formed by dissolv-Its prepa- ing pure silver in diluted nitrous acid of commerce, and ratl0n {?v • i i • , r,-,, , . medical evaporating the solution to dryness. 1 he dry mass is next use. exposed, in a crucible, to a heat gradually increased, until it melts and floyvs like oil. It is then poured into cylindrical iron moulds, which are previously anointed with tallow, and heated. 3. Nitrate of silver is soluble in its oyvn weight of cold Its proper- water. It is not deliquescent in the air; but when exposedties* to a strong light, the silver is in part deoxidized. When heated, it melts, and when cool, it forms a grey coloured mass, crystallized internally in needles. It is only after fu- sion, that it is employed in medicine and surgery. When exposed to a red heat, or placed upon burning coals, it detonates, and the silver is -revived. It has the properly of detonating also, when mixed with phosphorus and struck with a hammer. Most of the metals, particularly mercury and copper, are capable of precipitating the silver from its solution in the metallic state. It is composed of Nitric acid 54—one atom. Oxide of silver 118—one atom. 172 '4. Nitrate of silver is a very important salt in the hands Usesinsur- of the surgeon. Its property of decomposing animal sub- Sery; stances renders it useful in removing fungous excrescences and callous edges of ulcers, and for destroying strictures of the urethra. It is the most manageable caustic employed by surgeons; and, for the purposes just enumerated ajid 396 SALTS). dSu* ii m^ny others» no other caustic can be used with equal ad- . v'si0n ' vantage. In th. form of a weak solution, it is a good stimu- lating application to indolent ulcers. and in me- It has been employed internally for the cure of epilepsy, dicine. anci some o^er diseases. It must be admitted that it is an active substance; but how far it may be suited to the treat- ment ot epilepsy, requires to be more satisfactorily ascer- tained. Its dose is one-fourth of a grain, repeated several times a day, and gradually increased. Arsenite of VI. Arsenite qf Silver.—When a solution of nitrate of silver *i * i • silver is dropped into a solution containing arsenious acid, this salt falls in the form of a yellow precipitate, yvhich af- tenvards becomes of a brown colour. The property, yvhich the oxide of silver possesses, of combining with arsenious acid, whenever it nn ets with the latter, has suggested the employment of nitrate of silver for the detection of this deleterious substance. VII. Hydrofluate of Silver.—Usual chemical name, Fluate of Silver.—Hydrofluoric (fluoric) acid has no action on me- tallic silver; and hence silver may be conveniently used in vessels for containing this acid; but it readily dissolves the oxide of silver. The hydrofluate, thus formed, has a strong metallic taste, and is very soluble in water. It does not crystallize. Salts of ox- Of the remaining salts of oxidized silver, there have been idized sd- m0re or less described by chemists, the sulphite, selenate. ver, omit- . , , J , . ' .* ', » ted. nitrate, carbonate, borate, phosphate, arseniate, chromate, molybdate, sulphocyanate, purpurate, oxalate, succinate, acetate, tartrate, potasso-tartrate, benzoate, saclactate, ci- trate, mellate, malate, lactate and zumate; but these salts possess too little interest to be noticed. The rest of the salts of oxidized silver, amounting in number to 35, are unknown. Their gen- The salts of oxidized silver may be distinguished by the perties0 following properties or marks. 1. When exposed to the action of the blow-pipe upon burning charcoal, they are decomposed, and a globule of silver is obtained. 2. Ferrocyanate of potash occasions, in their solutions, a white precipitate. 3. Hydrosulphate (hydrosulphuret) of potash occasions a black precipitate. 4. Hydrochloric (muriatic) acid, or the chlorides of po- tassium or of sodium occasion a yvhite heavy flaky,precipi- tate, resembling curd. This precipitate is chloride of silver (horn silver). SALTS OF OXIDIZED GOLD. 397 5. A solution of sulphate of iron precipitates the silver Chap. IV. in the metallic state from solutions of these salts* 6. A plate of copper, placed in their solutions, precipi- tates the silver in the metallic state. SECTION XXVIII. SALTS OF OXIDIZED GOLD. Salts of Oxidized Gold are combinations of the per- Salts of ox- oxide of gold with the different acids. Unless there existsl(]tzed &oW* a simple hydrochlorate of gold, which is very doubtful, pounds. the protoxide of gold enters, as a constituent, into no salt. Only three of these salts are certainly known: they are the following. I. PERHYDROCHLORATE OF GOLD. (Usual chemical name, Muriate of Gold.) 1. When a mixture of one part of nitric acid and four Perhydro- parts of hydrochloric acid is poured upon gold, the metal Co|d'rate of is immediately attacked, the action being attended with efftrvescence, owing to the disengagement of deutoxide of azote (nitrous gas). The solution formed is of a deep yellow colour. It has the property of tinging the skin, as well as almost all animal and vegetable substances, of a deep pur- ple colour. When evaporated, perhydrochlorate of gold is deposited in crystals, possessing a fine yellow colour. 2. This salt is exceedingly deliquescent. Its taste is acrid Its propei-- and somewhat bitter, but not in the least metallic. Whenties- heated, it gives out chlorine, and is converted into a straw- coloured mass, yvhich is supposed to be the simple hydro- chlorate. It is decomposed by the alkaline salifiable bases, peroxide of gold being precipitated in the form of a yellow powder; but ammonia, potash or soda, if added in sufficient quantity, re-dissolves this precipitate, and forms a triple salt. It is decomposed also by most of the metals, and the gold thrown down, either in the metallic state, or in the form of a purple powder. When iron, zinc, copper, bis- muth, or mercury is plunged into its solution, the gold is precipitated in the metallic state. The gold is precipitated in the form of a purple poyvder by lead, tin or silver. It is precipitated also, from the solution of this hydrochlorate, by means of sulphate of iron, which becomes converted into a persulphate; but no effect is produced by the persul- phate of iron ready formed. By a similar action, hydrochlo- 398 SALTS. Book I. Division II It is preci- pitated hy hydrochlo- rate of tin, the precipi tate being the purple powder of Cassius. Proposed as an anti- syphilitic remedy. Persul- phate of gold. Pernitrate. rate of tin throws down protoxide of gold, combined with peroxide of tin; the tin being peroxidized, and the gold re- duced to the state of protoxide, by a transfer of oxygen from the latter to the former. This compound oxide is the purple precipitate of Cassius, and is used to give a red colour to porcelain and glass. On the other hand, the perhydro- chlorate of tin has no effect on the solution of the perhydro- chlorate of gold; as the oxide, which it contains, is already combined with a maximum of oxygen, and is, therefore, incapable of reducing the gold to the state of protoxide. 3. Different preparations of gold have been proposed by Dr. Chrestien as antisyphilitic remedies. The use of the peroxide with this view has already been noticed. Besides this oxide, Dr. Chrestien has proposed the perhydrochlo- rate just described combined with chloride of sodium (common salt), the purple powder of Cassius, and the am- moniated oxide. All of them were employed by friction on the tongue, cheeks and gums. The preparation of the perhy- drochlorate is by far the most active of those which he em- ployed, and was prescribed by him in doses of from -rVth to Tfrth of a grain, mixed with starch or charcoal. II. Persulphate of Gold.—When-peroxide of gold is treat- ed yvith warm sulphuric acid diluted with water, a solution of this salt is formed, having a yellow colour and a very styptic taste, and always containing an excess of acid. III. Pernitrate of Gold.—When concentrated nitric acid is poured upon peroxide of gold, it is dissolved; and there is formed a solution of this salt, possessing a brown colour, and containing an excess of acid. When treated with water, the peroxide is precipitated. The remaining salts of oxidized gold, amounting in number to 60, are unknown. Salts of ox- The salts of oxidized gold may be distinguished by the Kno™following properties or marks. 1. Their solutions in water have a yellow colour. 2. Ferrocyanate of potash occasions a white or yellowish- white precipitate, when poured into their solutions. 3. A plate of tin or hydrochlorate of tin occasions the purple precipitate of Cassius. 4. Sulphate of iron throws down the gold in the metallic state. SALTS OF OXIDIZED PLATINUM. 399 Chap. IV. SECTION XXIX. SALTS OF OXIDIZED PLATINUM. Salts of Oxidized Platinum are combinations of the Saitsofox- oxides of platinum with the different acids. Two only ofidized Pla- these salts will be described. whTcom- I. Perhydrochlorate of Platinum.—Usual chemical name, ^",^0- Muriate of Platinum.—When sixteen parts of a mixture, chlorate of composed of one part of the strongest nitric acid and three Platinum- parts of hydrochloric acid, are boiled upon one part of platinum, the solution of.the metal is gradually effected, being attended with a violent effervescence. The solution formed is at first of a yellow colour, which gradually deep- ens until it becomes of a deep red. It is exceedingly acrid and caustic, and tinges the skin of an indelible dark-brown colour. When sufficiently concentrated by evaporation, per- hydrochlorate of platinum is deposited in the form of crys- tals of a reddish-brown colour. This salt has a disagreeable, astringent, metallic taste. When cautiously heated nearly to redness, it is converted into perchloride of platinum. If the heat be still farther increased, the chlorine is driven off and nothing remains but the pure platinum. II. Sulphate of Platinum—This salt may be obtained by Sulphate of boiling to dryness, in nitric acid, the black powder precipi- platinum. tated from a solution of platinum in hydrochloric acid as- sisted by nitric acid, by means of hydrosulphuric acid gas, passed through it in a stream. This black powder is a sul- phuret of platinum, mixed with hydrosulphuric acid and sulphur. When it is boiled to dryness in nitric acid, the sul- phur becomes acidified, and the platinum oxidized, where- by it is converted into a sulphate of platinum. This salt is in the form of a porous crust, of a dark-brown colour, approaching to black. It is brittle and easily reduced to powder. Its taste is acid, metallic and somewhat caustic. It has the property of slightly reddening vegetable blues. It is very deliquescent, and consequently very soluble in water. The sulphuric acid cannot be separated from it by the usual methods, owing to the tendency which it pos- sesses of forming triple salts with most of the alkaline Forms tvi-' and earthy salifiable bases. When heated to redness, it is pie salts. entirely decomposed; oxygen and sulphurous acid being disengaged, and a strong fuming sulphuric acid, obtained. The residuum consists of pure platinum. The following are the triple salts which this sulphate is capable of forming; namely, the ammonio-sulphate, potasso- 400 S\LTS. Book! sulphate, soda-sulphate, barvto-sulphate and alumino-sul Division II. -i--~ t,or.ate of solution, which does not crystallize. When hydrochlorate of ammonia (sal ammoniac) or nitrate of potash (nitre) is added to this solution, no precipitate appears; but a triple salt is formed with ammonia or potash, according to the substance added. II. Persulphate of Rhodium.—-When hydrosulphate (hy- persui- drosulphuret) ot ammonia is mixed with the compound of phate. chloride of sodium and peroxide of rhodium, a sulphuret of rhodium precipitates. When fuming nitric acid is boiled to dryness upon this sulphuret, it becomes changed into a persulphate. This salt deliquesces in the air, and assumes a red colour. When dissolved in water and evaporated, it is converted into a syrupy, orange-coloured mass. III. Pernitrate of Rhodium.—Peroxide of rhodium dis-Pernitrate. solves in nitric acid, and forms a red solution, yvhich does not crystallize. The rest of the salts of oxidized rhodium are unknown. Salts of oxi- The salts of oxidized rhodium may be distinguished by ,'jj'^ hh0°^ the folloyving properties or marks. know'n. 1. Their solutions in yvater are red. 2 Neither ferrocyanate nor hydrosulphate of potash oc- casion any precipitate in their solutions. 3 E 402 SALTS. Book I. 3. Ammonia, potash or soda throws dovvn from their so- ms,on IL lutions a yellowish powder, soluble in excess of these alkaline bases. SECTION XXXII. SALTS OF OXIDIZED IRIDIUM. Salts of oxi- These salts have heretofore been but very imperfectly di«dindi- examined: the only one which has been formed is the hy- drochlorate. They may be recognised by the following marks. 1. They are soluble in water. The solution is at first green, but afterwards, by concentration in the open air, becomes red. 2. Their solutions are rendered colourless, when ferrocy- anate of potash, or infusion of nut-galls is dropped into them. SECTION XXXIII. SALTS OF OXIDIZED OSMIUM. Salts of oxi- It has already been mentioned, that, strictly speaking, „medo0*™* the oxide of osmium is not a salifiable base, and conse- strictiy quently that no such compound as a salt containing this speaking, OXlde is known to exist. But it is reasonable to suppose, that it is unknown as a salifiable base, not because it is in- capable of forming salts, but in consequence of the imperfect manner in which its chemical relations have been investi- gated. SECTION XXXIV. SALTS OF OXIDIZED TITANIUM. Salts of oxi-These salts are combinations of the protoxide or peroxide dizedtita- f titan;um wjtn different acids. The deutoxide is not mum; what . , • • r i r\ i compounds, known to enter into the composition ot any salt, uniy four of these compounds will be noticed. I. Perhydrochlorate of Titanium.—Usual chemical name, Muriate of Titanium.—Hydrochloric acid has no action on deutoxide of titanium; but it dissolves readily the percar- bonate. SALTS OF OXmiZED ANTIMONY. 4Q3 II. Sulphate of Titanium.—Boiling sulphuric acid has Chap, iv. no action upon deutoxide of titanium; but it oxidizes and dissolves a portion of metallic titanium. The solution, when evaporated, is converted into a white, opaque, gelatinous mass. III. Pernitrate of Titanium.—Nitric acid exerts no action upon deutoxide of titanium, and scarcely any on the metal itself; but it dissolves, by the assistance of heat, the per- carbonate oftitanium. The solution, when evaporated, yields transparent crystals of this nitr te. IV. Percarbonate qf Titanium.—This salt may be form- ed by melting together one part of deutoxide of titanium, and six parts of carbonate of potash, and washing the mass formed completely with water. A white powder, with a slight red tinge, is left behind undissolved, yvhich consists of the percarbonate. The rest of the salts of oxidized titanium are unknown. The salts of oxidized titanium may be known by the fol- Their dis- lowing characters. tinguishing 1. They are generally colourless, and, in some degree, soluble in water. 2. Carbonate of potash or of soda occasions a white flaky precipitate in their solutions. 3. Ferrocyanate of potash occasions a grass-green preci- pitate, mixed with brown. 4. Hydrosulphate of potash occasions a dirty grass-green precipitate. 5. Infusion of nut-galls occasions a very bulky reddish- brown precipitate. SECTION XXXV. SALTS OF OXIDIZED ANTIMONY. The reader has already been informed, that of the three Salts of oxi- compounds formed by antimony with oxygen, that onedized anti- only, which contains the least oxygen, is a salifiable base, ™h!a com- The other two are acids, and, according to the quantity pounds. of oxygen which they contain, are distinguished by the names of antimonious and antimonic acids. It is this cir- cumstance of the different agency of these compounds, in the formation of salts, which has led to the classification of antimony as an intermediate combustible. The salts to be described here are accordingly compounds of the oxide of antimony with the different acids. 404 SALTS. Book I. Division II. Oxide of antimony combines vith hydro- sulphuric acid, form- ing hydo- sulphate of antimony, or kermes mineral. Its prepa- ration for medical use. Its compo- sition. Oxide of antimony is not known to combine with sulphuric acid; but with hydrosulphuric acid (sulphuretted hydro- gen), it forms hydrosulphate of antimony. I. HYDROSULPHXTE OF ANTIMONY. (Usual chemical nime, Hydrosulphuret of Antimony.— Brown Antitnoniated Sulphur, of the 'ublin college.—Common name, Kermes .M.neral) 1. When hydrosulphate of ammonia or of potash is drop- ped into an acid solution of antimony, this salt precipitates in the form of a beautiful orange-coloured powder. 2. It is directed to be prepared by the Dublin college by the following process: Melt together equal parts of prepar- ed sulphuret of antimony and carbonate of potash in a cru- cible; and when the miss is cool, reduce it to powder, and then boil it in a glass vessel with forty times its yveight of water for an hour. The vessel is then taken off the fir-, and as soon as the liquor has become clear, it is cautiously de- canted and set aside to cool. During the cooling, the hy- drosulphate is deposited in the form of a powder. 3. The manner in which the hydrosulphate is formed, in the foregoing process, is thus explained. Upon fusing to- gether carbonate of potash and sulphuret of antimony, car- bonic acid is disengaged, and the mass obtained is a mixture of the sulphurets of antimony and of potash. Water, by being boiled upon the mixed sulphurets, becomes decom- posed; its oxygen oxidizes the antimony, while its hydrogen converts the sulphur into hydrosulphuric acid. Part of the acid, thus formed, combines with the oxide of antimony, while the remainder unites with the potash; so that the mixed sulphurets become a mixture of hydrosulphate of antimony and hydrosulphate of potash. Now the former of these salts is soluble, at the boiling temperature, in the latter, but not at the ordinary temperature of the air: heuce, therefore, it precipitates as the liquid cools. 4. The method of preparing this salt was first discovered by Glauber, and afterwards by Lemery, the elder. It ac- quired great celebrity, as a medicine, about the beginning of the last century. Its preparation was kept secret before 1720, in which year the French government purchased the process and made it public. 5. Kermes mineral, when obtained from the sulphuret of antimony and potash, was found by Thenard to consist of Hydrosulphuric acid 20*30 Oxide of antimony 72*76 Sulphur 4*15 Water and loss -"79 100*00 SALTS OF OXIDIZED ANTIMONY. 405 This analysis does not agree well with any atomical sup- Chap. iv. position for the composition of this salt. It evidently ap-~ pears that the compound cannot be much modified, in its medical properties at least, by the presence of 4 per cent. of sulphur. Kermes mineral may therefore be considered, without much want of precision, a hydrosulphate of anti- mony. 6. When the liquor, from which the kermes mineral has Hydrosnl- precipitated, is treated with diluted sulphuric acid, a preci- phite of an- • . r i l-lj'/v • ■..• r ^l tllllOOV, or pitate is formed, which differs in composition, from the one golden sul- last described, in containing a larger proportion of sulphur, ph""-- According to the plan of nomenclature adopted in this work, it may be called a hydrosulphite of antimony. Its usual chemical name is hydroguretted sulphuret of antimo- ny', formerly called, golden sulphur* It is officinal with the British colleges. 7. Kermes mineral is an active preparation of antimony, Medical and certainly not sufficiently attended to by medical practi- properties tioners in the United States. It has the usual properties of mineral; the antimonial remedies. Its dose is from a grain to a grain and a half. It is very apt to excite vomiting. The golden and of gold- sulphur is very similar, in medical properties, to the kermes ensulPl»uf. mineral; but on account of the additional quantity of sul- phur which it contains, it may be given in larger doses. Oxide of antimony is not known to combine with phospho- Oxide of ric acid; but with phosphate of lime, it forms phosphate *"m™jnned of lime-and-antimony. with phos- phate of II. PHOSPHATE OF LIME-AND-ANTIMONY. lime, forms phosphate {Oxide of Antimony with Phosphate of Lime, of the Edinburgh College. oflime-and- Common names, Antimonial Powder—James's Powder.) antimonv, 1. This compound is directed to be prepared by the Bri- powder. tish colleges by the following process. Put a mixture of equal parts of sulphuret of antimony and shavings of harts- horn in a red-hot iron pot, and stir it constantly, until it is burnt into a mass of a grey colour. It is then removed from the fire, ground into a powder, and placed in a crucible, over which there is luted another, perforated at its bottom. The mass is now exposed to a white heat gradually raised, and kept at that temperature for two hours. It is then with- drawn from the fire, and, when cold, ground into a fine powder. It now constitutes the preparation in question. 2. To understand the foregoing process, it must be recol- lected, that shavings of hartshorn are phosphate of lime containing some animal matter. When they are exposed to a white heat, the animal matter is burnt off, and they be- come converted into pure phosphate of lime. During the 406 SALTS. Book I. same exposure, the sulphuret of antimony, with which the Division II. shavings are mixed, becomes converted into oxide of anti- mony, and, thus altered, combines with the phosphate. 3. The formula, just given, was invented by Dr. Pear- son of London. It furnishes a preparation, yvhich agrees in constituents yvith the celebrated antimonial powder of Dr. James. Its compo- 4. This triple salt is composed of SlUOn- T»U L fl- A* Phosphate of lime 43 Oxide of antimony 57 Its medical 5. Phosphate of lime-and-antimony is a very valuble an- properues. timonial preparation. In doses of from three to eight grains, repeated every third or fourth hour, it is well suited to the treatment of febrile diseases, and acts as a diaphoretic and antiphlogistic remedy. In larger doses, its operation is both emetic and cathartic. Oxide of Tartaric acid has no action upon metallic antimony, and is formTatri- capable of dissolving small portions only of its oxide; pie salt but bitartrate of potash (tartar) combines with the oxide, ^tateof^ot- an(* f°rms tartrate of potash-and-antimony. ash, called m TARTRATE QF POTASH-AND-ANTIMONY. tartrate of potash-and- (Tartrite of Antimony of the Edinburgh college.—Also called, Tartarized An- antimony, timony—Antimoniated Tartar.—Common name, Tartar Emetic.) or tartar a emetic. \t T/he London and Edinburgh colleges direct the pre- paration of this triple salt by the following process: Boil a mixture of three parts of crocus of antimony (a sulphuretted oxide of antimony) and four parts of bitartrate of potash (tartar), in thirty-two parts of distilled water, in a glass vessel, for about a quarter of an hour. Filter the liquor through paper, and set it aside to crystallize. 2. In the above process, the oxide of antimony is dissolv- ed in the extra atom of acid of the bitartrate of potash; so that there is formed a tartrate of antimony, while the bitartrate is reduced to a tartrate (soluble tartar). The tar- trate of antimony, however, does not combine with all the tartrate of potash formed, but a proportion of it only. Hence it is that the liquid, from which tartar emetic is deposited, is a solution of tartrate of potash. 3. Besides the crocus of antimony, several other forms of oxide of antimony have been employed in the formation of this triple salt. These are the glass of antimony (a sul- phuretted oxide) and subhydrochlorate of antimony (pow- der of Algaroth). When the glass is used, its sulphur is left undissolved, as is the case with the crocus; and when the subhydrochlorate is employed, the small portion of acid, which it contains, combines with the potash of the bitartrate SALTS OF OXIDIZED ANTIMONY. 407 and remains in solution. The Dublin college employs the Chap, iv. uncombined oxide of antimony, which is precipitated from chloride of antimony (buttt r of antimony) by means of car- bonate of potash. This is perhaps the best method for pre- paring tartar emetic; but at the same time it is the most expensive. 4. Tartrate of potash-and-antimony has a white colour Properties and a crystalline appearance. When exposed to the air, it ofmt'^v effloresces and loses its transparency. It is soluble in fifteen parts of water at the temp- rature of 60°, and in three parts of boiling water. When exposed to heat, its acid is destroy- ed, and there remains behind a mixture of potash and oxide of antimony. It is decomposed by the alkaline salifiable bases and their carbonates, by the hydrosulphates, and by several of the metals. It is decomposed also by vegetable juices, and by decoctions of vegetable substances, especially of such as are astringent and bitter. Hence care must be taken not to associate these substances with tartar emetic in compound prescriptions. 5. The composition of tartar emetic may be thus stated: its compo- 182 parts, or one atom of bitartrate of potash require for8,tl0n' saturation 98 parts of oxide of antimony. As, however, the oxide combines only with the extra atom of acid in the bitartrate, there consequently results 165 parts of tartrate of antimony, composed of 67 parts, or one atom of tartaric acid, and 98 parts of oxide of antimony; and 115 parts, or one atom of tartrate of potash, composed of 67 parts, or one atom of tartaric acid, and 48 parts, or one atom of potash. The. 165 parts of tartrate of antimony, during the pre- cipitation of the tartar emetic, combine with 72 parts only of the tartrate of potash formed, the remainder of the tar- trate of potash, amounting to 43 parts, being held in solu- tion. The above numbers are calculated from an analysis per- formed by Thenard. It is easy to perceive that they do not accord yvith any supposition of atomic combination. 6. Tartrate of potash-and-antimony is of indispensable Tartar e- utility in the practice of medicine. In doses of from three 1™^^^- to five grains, it is a prompt and effectual emetic: and in bie utility doses of from one-eighth to one-fourth of a grain, repeated at |n the i,rac- ■ . 1** 1*1 • r T1CC Ot IDC* short intervals, it is one ot the most certain means ot repres- dicine. sing febrile action, %hich can be employed. When dissolv- ed in wine, it forms the valuable medicine, familiarly known by the name of antimonial wine. This preparation is offici- nal with the different colleges; but it is to be regretted, that 408 SALTS. Book i. it is not of uniform strength. The wine ordered by the Division li. Edinburgh college contains two grains of the triple s tit to the ounct; while the wims of the London and Dublin col- leges contain twice that quantity. Saltsofoxi- Besides the salts of oxidized antimony just described, mony,8" there have been formed and slightly noticed by chemists, omitted, the oxalate, acetate and benzoate. The rest ot these salts are unknown. Their gen- Xhe salts of oxidized antimony may be recognised by perties. -ne following properties or murks. 1. Their solutions in acids are usually of a brownish- yellow colour, and in most cases let fall a white precipi- tate upon the addition of water. a. Hydrosulphate of potash occasions an orange-coloured precipi.ate in their solutions. 3. When a plate of iron or zinc is plunged into their so- lutions, a black precipitate immediately forms. SECTION XXXVI. SALTS OF OXIDIZED TELLURIUM. Saltsofoxi- These salts are the compounds, into yvhich oxide of tel- rium; what^u"um enters as a constituent, not as an acid, but as a base. compounds. It was the double office of the oxide of tellurium in its dif- ferent saline combinations, which caused the metal itself to be associated with antimony, under the title of interme- diate combustibles. Tellurium, however, differs from anti- mony in this respect, that, being capable of forming but one oxide, the same oxi .e, under different circumstances, appears both as an acid and as a salifiable base; whereas it is different oxides of antimony, which assume the double office. The hydrochlorate, sulphate and nitrate of tellurium have been formed by Berzelius; but they are too unimpor- tant to be described. No other salts, into which the oxide of tellurium enters as a salifiable base, are known. General The salts, into which the oxide of tellurium enters as a ofthe'iwrtt constituent, may be recognised by the following characters. into which 1. Potash or soda, when dropped into their solutions, telhirium occas'ons a white precipitate, yvhich disappears when either of these alkaline bases is added in excess. ALCOHOL. 409 2. Ferrocyanate of potash occasions no precipitate; but Chap.v. hvdrosulphate of potash throws down a brown or blackish enters as a precipitate. constituent. 3. Iron, zinc, and antimony throw down the tellurium in the form of a bLck powder, which acquires the metallic lustre when rubbed. CHAPTER V. OF UNSALIFIABLE COMPOUNDS. It is proposed, in the present chapter, to treat of the more important unsalifiable compounds. They will be ar- ranged under the six following heads: 1. Alcohol. 4. Fixed oils. 2. Ethers. 5. Spermaceti. 3. Volatile oils. 6. Soaps. These heads will furnish the titles of the six following sections. SECTION I. OF ALCOHOL. (Common name, Spirit of Wine.) 1. By the distillation of various fermented liquors, a pe-Product of culiar liquid is obtained. The distilled product of yvine is the ',l:'ll!a' brandy ; of the fermented juice of the sugar cane, rum; and mented li- of the fermented juice of the apple or of the fermented in- *luors- fusion of malt, whiskey or gin. All these different kinds of ardent spirits are essentially the same. They consist of pure spirit or alcohol, diluted with water, and containing a Ardent little oil or resin, to which they owe their flavour and colour. *Pirit is di- When these ardent spirits are distilled, there is obtained hoi? a C°^ a light transparent liquid, known in commerce by the name of rectified spirits. This liquid, however, is not pure alcohol; it still contains a considerable portion of water. The method, formerly practised to separate the water from the rectified spirits, was to mix them with carbonate of potash (salt of tartar), previously made dry and warm. 3 F 410 UNSALIFIABLE COMPOUNDS. Book I. This salt is insoluble in pure alcohol; but combines yvith Division II. avidity with yvater. Hence it is, that, upon being mixed with the spirits, it separates the greater part o the yvater yvhich they contain, and falls to the bottom of the vessel employed. The spirits hayc now become lighter and purer than before; but they still contain a considerable quantity of y\ater. Absolute Alcohol, absolutely pure, was first obtained, in 1796, alcohol, , T • r r» ii T-n .- i • 1 • first obtain-">' -L.oyvitz ot retersburgh. I he process ot this chemist is ed by Low-as follows: Mix together, in a retort, two parts of carbo- nate of potash, perfectly dry and still yvarm, and one part of alcohol, brought to the specific gravity of 0.821, by means of the common treatment yvith carbonate of potash. This mixture forms a solid mass, without any superabun- dance of alcohol. Allow it to remain for twenty-four hours, and then distil by a heat, so gentle as that about two seconds will elapse betyveen the falling of the drops of the distilled liquor from the beak of the receiver. When the interval becomes greater, the process must be stopped. In this way, an alcohol is obtained of the specific gravity of 0*791: it may be considered as absolute or pure alcohol. Richter obtained alcohol of the specific gravity of 0*792, by distilling an alcohol of the specific gravity of 0*821, off a little more than its yveight of chloride of calcium (muriate of lime), pulverized and yet warm, and which had previ- ously been exposed to a red heat. Properties 2. Absolute alcohol, obtained by the processes just given, oj" absolute is a transparent colourless liquid, possessing a pleasant smell, and strong, penetrating, agreeable taste. Its specific gravity, as has already been mentioned, is 0*791. When mixed with yvater, its specific gravity becomes higher in proportion to the quantity added, and the mixture is at- tended by a condensation. Hence the purest spirits are those which are specifically the lightest. 3. Alcohol does not congeal, when exposed to the greatest artificial cold which has hitherto been produced. It has been subjected to a cold of — 91° without losing its liquidity. 4. It is a very volatile liquid. When of the specific gra- vity of 0*820, its boiling point is at 176°. In a vacuum, it boils at the temperature of 56°. From this it is evident, that, were it not for the weight of the atmosphere, it would always exist in the form of an elastic vapour. This vapour possesses the mechanical properties of common air. Its specific gravity is 1*61. 5. When alcohol is exposed to a high temperature, it takes fire and burns with a blue flame, leaving no residuum. The products of its combustion are water and carbonic acid. ALCOHOL. 411 6. Alcohol is capable of dissolving a small portion of Chap, v. phosphorus. It dissolves a portion of sulphur also. When *~ water is added to sulphuretted alcohol, the sulphur is pre- cipitated. 7. Alcohol has the property of combining with ammonia; it combines with yvhich it forms the officinal preparation, called ammo- w>tl\ani- mated alcohol, or spirit of ammonia. This compound is Arming best prepared by mixing together one part of hydrochlorate ammonia- of ammonia (sal ammoniac) and two parts of lime, and pour- teJ alcoho • ing upon the mixture, placed in a retort, four parts of al- cohol. The yvhole is then distilled to dryness. The hydro- chloric acid of the hydrochlorate combines w ith the lime in such a way as to form chloride of calcium and yvater; while the ammonia, combined with the alcohol, distils over. Several active articles of the materia medica are dissolv- Ammonia- ed in ammoniated alcohol. The compounds thus formed te',Jaleoho1* ,, , • , , -i • used as a are called ammoniated or volatile tinctures. solvent for 8. Alcohol is capable also of dissolving potash and soda, several ac- and forms with them, a reddish-coloured acrid solution. Itcjne8me is by means of alcohol, that these alkaline bases are gene- rally obtained in a pure state. It is decomposed by the ac- tion of sulphuric and nitric acids; but all the other acids are soluble in it, except phosphoric acid and the metallic acids. It is capable of dissolving a considerable number of salts. Some of these compounds, however, are entirely inso- luble in it. When it holds in solution certain substances, their presence is indicated by the peculiar colour of its flame. Thus boracic acid and the salts of oxidized copper tinge its flame green; nitrate of strontian, purple; chloride of calcium, red; nitrate of potash and perchloride of mer- cury, yelloyv. 9. It is composed of Composi- Hydrogen 3—three atoms. Uonofaico- Carbon 12—tyvo atoms. Oxygen 8—one atom. 23 The atomic statement, above given, of the ultimate con- stituents of alcohol coincides very^ nearly yvith an analy- sis, performed with great care by Theodore de Saussure, in 1813: it may, therefore, be considered a pretty near ap- proximation to truth. The proximate constituents of this liquid are unknoyvn; as there are no data, by which to indi- cate the manner in yvhich its ultimate constituents are united. 10. The effects of alcohol in a diluted state upon the Effects of human body, under the various forms of ardent spirits, are anCOuo1 on too yvell knoyvn to require detail. They are certainly those 412 UNSALEABLE COMPOUNDS. Book I. of a most powerful and diffusive stimulus. In pharmacy, Division H.aicoholT generally in the diluted state, is very much era- constitu- ployed to extract the virtues of certain medicinal substances. The solutions, thus formed, are called tinctures. It is to be regretted, however, that so many medicines are exhibited, prepared with this menstruum, more especially in chronic diseases. Their habitual use not unlrequently renders the stimulus of the alcohol, at first merely grateful to the sto- mach, at last indispensably necessary, to create, artificially, that comfortable tone of animal feeling, without which to live is to be miserable. SECTION II. OF ETHERS. General Ethers are very fragrant and volatile liquids, formed by properties distilling alcohol with various acids. The reader has alrea- dy been made acquainted yvith the liquid lormtd by the union of hydroguret of carbon (defiant gas) and chlorine, under the name of chloric ether. Besides this compound, six distinct ethers have been described by chemists; namely hydrochloric {muriatic) ether, hydriodic ether* sulphuric ether, nitric ether, formic ether, and acetic ether. Three only of these ethers will be described; namely hydrochloric, sulphuric and nitric ethers. I OF HYDROCHLORIC ETHER. (Usual chemical name, Muriatic Ether.) Hydrochlo- 1. This ether may be obtained by distilling a mixture of ric ether; equal bulks of hydrochloric acid and alcohol, both obtained ejj7° tain*as strong as possible. The retort, from which the distilla- tion is made, must have a tube luted to its beak, which should communicate with a glass jar, half full of water, and furnished with three mouths. From the middle mouth, a tube of safety should proceed; and from the third mouth, a tube, so connected with the pneumatic trough, as to ena- ble the operator to collect the gaseous product. As soon as the heat is applied, the gaseous product passes to the vessels in the yvater trough; while any alcohol, acid or water, which may be driven over, is arrested in the jar with the three mouths. The gas thus obtained is hydrochloric ether. Properties. 2. Hydrochloric etherial gas has the strong smell of ether, and a syveetish taste. Its specific gravity is 2*219. When exposed to a cold of 52°, it is condensed into a liquid, in which state it is colourless and has the same taste and ETHERS. 413 imell as when in the for n of gas. At the temperature of Chap. v. 4;°, i's specific gravity is 0*874. It burns readily with a"~" green flame; and, at the same time, a very considerable portion of hydrochloric acid is disengaged in a state of va- pour. Notwithstanding, the presence of this acid is not indicated by the usual tests. 3. This ether is composed of Composi- Hydrochloric acid 29*44 tion- Carbon 36*61 Oxygen 23*31 Hydrogen 10-64 100*00 II. OF SULPHURIC ETHER. (Formerly called, Vitriolic Ether.) 1. Sulphuric ether may be prepared by distilling a mix-Sulphuric ture of equal parts of alcohol and sulphuric acid, in a retort, ethe,7 Pre" to which is luted a large receiver, surrounded with ice or l>ara cold water. A vapour comes over, which condenses in the receiver and runs down its sides in striae. This condensed vapour is the sulphuric ether. It is rendered impure, how- ever, by admixture of sulphurous acid, alcohol and water. It may be purified from the first, by mixture with a lit- tle yvater and a portion of lime, and a re-distillation. It may be deprived of the water, by mixture with dry pulve- rized carbonate of potash. The alcohol is separated by means of dry chloride of calcium (muriate of lime), which combines with it and sinks, while the pure ether remains syvimming on the top. By pursuing these methods of puri- fication, sulphuric ether has been obtained of the specific gravity of 0 632, at the temperature of 60°. 2. Sulphuric ether is a colourless liquid, of a very fra- Properties, grant smell and hot pungent taste. It is exceedingly vola- tile and vaporizable. When poured out in the open air, it disappears in an instant, being converted into vapour, and produces, by its evaporation, a very considerable degree of cold. If a glass vessel, containing yvater and surrounded with a clothy be dipped in ether for several successive times, after it has previously evapor ited, the water in the vessel will be converted into ice. This ether does not combine yvith water. At the temperature of 98°, in the open air, it boils; but it boils at a temperature of — 20° in a vacuum. Its freezing point is at the temperature of — 46°. The specific gravity of its vapour is 2*58. It is very inflammable; and yvhen kindled in a state of vapour, it burns rapidly yvith a fine white flame. 414 UNSALIFIABLE COMPOUNDS. Book I. 3. It is composed of Division n Hydrogen 14*40 Composi- Carbon 67*98 Oxygen 1762 100-00 4. Sulphuric ether, mixed yvith tyvice its weight of alco- hol, forms the sulphuric ether with alcohol of the Edinburgh college; formerly called the dulcified spirit of vitriol. This compound is used in the formation of some ethereal tinc- tures. When prepared with cinnamon and other aromatics, it forms the aromatic sulphuric ether with alcohol of the same college. It enters also into the composition of the anodyne liquor of Hoff nan. 5. The aromatic sulphuric acid of the Edinburgh college, usually called the elixir of vitriol, is, in fact, an aromatic sul- phuric ether yvith sulphuric acid. It is formed by dropping, gradually, one part of sulphuric acid upon four parts of alco- hol, and digesting the mixture in a close vessel, at a gentle heat, for several days; at the end of which time, the aromatics are added. III. OF NITRIC ETHER. Nitric eth- 1. Thenard has ascertained, that the liquid, heretofore er; prepa- considered as nitric ether, is in fact a mixture of alcohol, water, ether, nitrous and acetic acids. To obtain nitric ether pure, this chemist devised the following process: Pour equal weights of alcohol, and nitric acid of the specific gravity of 1*283, into a retort. Prepare an apparatus, consisting of five tall and narrow glass jars, half filled with a saturated solution of chloride of sodium (common salt), and connect- ed together by means of a series of bent tubes. This con- nection by tubes is to be arranged in the following manner: the first tube is to pass from the top of the first jar to the bottom of the second jar; the second tube, from the top of the second jar to the bottom of the third, and so on of all the rest of the jars. The first jar is then to be connected yvith the retort by means of a glass tube, one end of which must be luted to the beak of the retort, and the other pass down to the bottom of this jar. The last jar is connected, by means of a tube, to the pneumatic trough. All the jars are noyv surrounded by a mixture of chloride of sodium (common salt) and snow, to keep them as cold as possible. A moderate heat is then applied to the retort. What gases become formed by the action of the heat, pass through the different solutions to the water trough. The ether itself is deposited in the different jars, and swims on the surface of the contained solutions. It is then separated, and may be Elixir of Vitriol.- ETHERS. 415 freed from nitrous and acetic acids by agitation, in a close Chap, v. vessel, with carbonate of lime (chalk), until vegetable b'.ues are no longer affected by its action. 2. Nitric ether, yvhen thus obtained, is a liquid, having a Properties. slightly yellow colour, and a very strong ethereal odour. Its taste is peculiar and strong.-It is somewhat heavier than alcohol, and much more volatile than sulphuric ether. It is but sparingly soluble in water, but dissolves in alcohol in every proportion. It burns brilliantly with a yvhite flame, like sulphuric ether. When kept for some time or heated, or when agitated yvith water, both nitrous and acetic acids become formed. It is liquid at the temperature of 70°, and .when the barometer stands at 30 inches; but if the heat be increased beyond this temperature, or the barometrical pres- sure lessened, it assumes the form of a vapour. Composi- tion. . It is composed of Oxygen 48*52 Carbon a 8*45 Azote 14-49 Hydrogen 8*54 100*00 The above is an analysis performed by Thenard. It does not agree well with the atomic theory. It is perceived that this ether differs from other ethers in containing azote as a constituent. 4. The nitrous ether of the Dublin college is an impure Nitrous nitric ether. It is formed by pouring a mixture of alcohol ether»an. and sulphuric acid upon dry and coarsely powdered nitrate trie ether. of potash (nitre), placed in a retort. The retort is furnished with a receiver, yvhich must be kept cool by means of water or snow. No artificial heat is requisite to produce the proper degree of action. The spirit of nitrous ether (sweet spirit of nitre) may be Sweet spi- considered a mixture of nitric ether and alcohol. It is rit of nitre, formed by distilling a mixture of one part of nitrous acid 0f „itric of the shops and three parts of alcohol, by the heat of boil- ether and ing water, into a receiver kept cool by cold water or snow. a c0 ° ■ The mixture of the acid and alcohol is made by adding the former by degrees to the latter, contained in a capacious phial immersed in cold water, and agitating the whole at every addition. The mixture must then be kept for seven days, before it is exposed to heat. Spirit of nitrous ether constitutes a very valuable medi- itg medical cine. Its chief property is that of a stimulating diaphoretic; properties. which fits it for exhibition in the latter stages of fevers, where the skin remains dry, and the febrile action has be- gun to abate. 416 UNSALIFIABLE COMPOUNDS. Book I. Division II. SECTION III. OF VOLATILE OILS. 1. There are a great number of these substances. It ic not intended, however, to give an account of each ot them individually; their general characters only will be noticed. General 2. Volatile oils mav be distinguished by the followine propcrUes , t-.. ° ,. ,. . , . ° ofvoiatile g>ener-u properties. They are usually liquid; but some- oils, times they have the consistence of butter. Their taste is acrid, and their smell, strong and fragrant. They are volati- lized by a heat under 212°. They are soluble in alcohol, and but imperfectly so in yvater. When dropped upon paper and exposed to a gentle heat, they evaporate entirely with- out leaving a greasy stain. This last circumstance, particu- larly, distinguishes them from the fixed oils. 3. Volatile oils are almost all obtained from vegetables; and from every part of the plant, except the substance of the cotyledons. On the contrary, the fixed oils are generally- contained in these portions of the plant. Method of 4. Sometimes volatile oils are obtained by simple expres- them?"5 sion; but, in general, they can be extracted only by dis illa- tion. The method is to put the part of the plant, containing the oil, in a still with water, and to apply a gentle heat: the volatile oil is driven over yvith the water, and is found syvim- ming on its surface. 5. The specific gravity of the volatile oils is very various. Most generally, however, it is beloyv that of yvater. The point at yvhich different volatile oils congeal varies very much also. Oil of anise and of fennel become solid at 50°, and oil of turpentine begins to melt at 14°. Several volatile oils require a cold as low as —17° for their congelation. Effects of 6. When volatile oils are exposed to the open air, their exposure to cojour gradually deepens, their odour diminishes, and they become more viscid. Bv long exposure, they at last assume the appearance of resins. When sufficiently heated, they take fire and burn with a clear bright flame, emitting a vast quantity of smoke. The products of their combustion, be- sides the soot, are water and carbonic acid. Action of 7. Volatile oils, by the action of chlorine, are converted chlorine jnto a yellow resinous substance. Oil of turpentine, in a ' state of vapour, passed through a glass tube along with this supporter, combines with it, and forms a thick, heavy, white oil, yvhich sinks immediately in water, and has a taste and smell resembling that of nutmegs. They dis- 8. Volatile oils dissolve a portion of sulphur. When di- VOLATILE OILS. 417 gested upon this substance, at the temperature at which it Chap. V. melts, they dissolve a portion of it, and acquire a brown ~; ~ i it- i r J 11 .-*-., solve sul- colour and a disagreeable taste and smell. Ihese combina-phur and tions are called balsams of sulphur. Volatile oils also dis- PhosP,l°- Bolve a small portion of phosphorus at a digesting heat, but they deposite it again as they cool. They are all more or less soluble in alcohol, ether, and the fixed oils. 9. Sulphuric acid acts with considerable energy upon the Action of volatile oils. It first dissolves them, then converts them the s.tronS-; . c . ' , , . , .er acids up* into a substance ot a resinous nature, and ultimately into on them. charcoal. Hydrochloric acid has much less action upon them than sulphuric acid: it combines with the oil of tur- pentine, and forms a compound very similar in appearance to camphor. Nitric acid, when thrown upon them suddenly in a concentrated state, generally sets them on fire; but when sufficiently diluted, it effects their solution, and con- verts them into a yellow substance, resembling resin. 10. Volatile oils are found to consist of hydrogen, carbon and oxygen, united in various proportions; but no exact analysis has been made of them. 11. Some of the volatile oils are used in the arts. They Their uses give to different perfumes their odorous properties. The oilin the artsJ of turpentine is used to dissolve resins, which are afterwards employed as varnishes and for many other purposes. 12. A great many volatile oils are employed in medicine, and in mefc Their chief use is to conceal the taste of the more nau-didne* seous medicines, by substituting an agreeable pungency. In many cases, the medicinal virtues of the substances, from which they are obtained, are preserved in the oil itself. Thus it is found that the oil of juniper berries is diuretic; that of scurvy-grass, antiscorbutic; that of mint, stomachic, and so of many others. The most important volatile oil, in a medical point of view, is the volatile oil of turpentine (spirit of turpentine). It is obtained by distilling the com- mon oil of turpentine along yvith yvater. Its principal properties are those of a diaphoretic and diuretic. When given in large doses, it operates with great power upon the urinary organs. This oil certainly deserves more attention than is generally bestowed upon it bv the practitioners of the United States. 3 c; 418 UNSALIFIABLE COMPOUNDS Book I. Division II SECTION IV. OF FIXED OILS. Gene™i 1. The fixed oils have the following general properties: of thTfixed l^ey are usually liquids, possessing a certain degree of oils- viscidity, and having an unctuous feel and mild taste. They are very combustible, and are insoluble in water, and nearly so in alcohol. Their boiling point is above 600°. When dropped upon paper, they leave a greasy stain, which is not removed by exposure to a gentle heat. 2. Fixed oils are obtained from both animal and vegeta- ble substances by simple expression. They are all lighter than water; but they differ from one another in the degree of their specific gravity. Their com- 3. Fixed oils, in a state of vapour, catch fire on the ap- cribed? es proach of an ignited body, and burn with a yellowish-white flame. It is on this property of the fixed oils, that the burn- ing of lamps and candles depends. By the approach of an ignited body to the wick, it catches fire; and sufficient heat is thereby produced to convert a portion of the tallow or oil into vapour, which immediately takes fire in the wick. The heat thus generated is sufficient to convert a fresh por- tion of the tallow or oil into vapour, which in its turn in- flames. In this manner, the flame is preserved as long as any talloyv or oil remains. The products of this combustion are water and carbonic acid. 4. All the fixed oils, which are liquid at the common temperature of the atmosphere, lose their liquidity when exposed to a sufficient degree of cold; but the congealing points of different oils are exceedingly various. 5. All the fixed oils, when exposed to the air, gradually absorb oxygen, become more and more viscid, and are at last converted into solids. Some oils, after having under- gone this change, remain transparent, while others become Divided in- opaque like tallow. Those which remain transparent are ods'andtat ca^ec^ drying oils; while those which become opaque are oils. denominated fat oils. Oils may be 6. Most of the fixed oils may be converted into drying made dry- 0j|s ^v artificial management, and are thereby rendered fit ins* artinci- J ° • j ally. for use by the painter and varnisher. The management Mi-nner in consists in boiling the oil for some time in an iron pot. It which this thereby acquires a deeper colour and greater consistency, owing to a partial decomposition; there being abundance of watery vapour and hydroguret of carbon separated during the boiling. For some purposes, the oil is set on fire and FIXED OILS. 419 allowed to burn for some time, yvhen it is extinguished by Chap, v. covering the vessel in which it is contained; after which- the boiling is continued, until the oil acquires the necessary viscidity, and loses, in a great measure, its unctuous quali- ties. It is common also, in many cases, in forming the dry- ing oils, to boil them with a portion of the semi-vitrified oxide of lead (litharge). The change which takes place in oils, whereby they are rendered drying, is not well under- stood. 7. The fixed oils dissolve a small portion of phosphorus Fixed oils by the assistance of heat. They dissolve readily a portion J'^Jj,*,. of sulphur, by the same agency. The solution formed is rus and sul- of a reddish colour, and when allowed to cool, deposites Phur- the sulphur in crystals. 8. The fixed oils are insoluble in water. When agitated They are with water, the mixture assumes a milky appearance; but l°*°g1!.ble m upon rest, the two liquids gradually separate, the oil swim- ming above the water. If a mucilaginous substance, such as gum arabic, be incorporated with the mixture, it becomes a kind of bond of union to the oil and water, which now con- stitute a permanently milky compound. These mixtures of oil and water, by means of mucilage, are called emulsions. When oily seeds, such as almonds, are triturated with water, the same kind of mixture is formed; because, in these seeds, a mixture of oil and mucilage exists ready formed. 9. Most of the fixed oils are but sparingly soluble in and but alcohol. This liquid takes up very little olive or almond snar'ngbr oil, but somewhat more of linseed oil; whereas it dissolves alcohol. any quantity of castor oil. In general these oils are more soluble in sulphuric ether than in alcohol. Like alcohol, sulphuric ether dissolves any quantity of castor oil. 10. The fixed oils unite readily with the alkaline and They unite earthy salifiable bases, and form compounds called soaps. j"j,tl?sa,ifia" But it would appear, that they do not unite with these bodies as oils, but undergo a singular change, at the mo- ment of saponification, yvhich will be explained hereafter. They also combine with salifiable bases of the third class, commonly called metallic oxides, and form compounds called plasters. 11. The action of acids upon the fixed oils has been but Action of very imperfectly ascertained. Sulphuric acid acts upon them fixed oils with considerable energy; they are at first converted into a black substance resembling bitumen; but if the action of the acid be allowed to continue long enough, they are ulti- mately entirely decomposed into yvater, charcoal, and an acid. Nitric acid has a more powerful action upon them. 420 UNSALIFIABLE COMPOUNDS Book I. Division II Rancidity explained. When poured suddenly upon the drying oils, they are set on fire. The same effect is produced upon the fat oiK, if the nitric acid employed be previously mixed with a portion of sulphuric acid. Nitric acid, sufficiently diluted, converts the dry ing oils into a substance like resin, and fat oils into a muss resembling tallow. 12. Fixed oils, upon keeping, are liable to undergo a change, yvhich is known by the name of rancidity. They become thick, and acquire a brown colour, an acrid taste, and a disagreeable smell. It is generally supposed that this change depends upon the presence of uucilaginous matter, yvhich many oils when newly extracted contain; but hoyv this matter acts is not known. It is ascertained, however, that an acid is generated during the conversion; since ran- cid oils have the property of changing vegetable blues to red. 13. The fixed oils are of indispensable use in pharmacy. Under the forms of tallow, mutton-suet and hogslard, they constitute the basis of all kinds of ointments and plasters. Among the most useful of them are the olive and castor oils. The latter furnishes the physician with an excellent mild purgative. 14. The fixed oils are compounds of hydrogen, carbon and oxvgen, united in various proportions. The only fixed oil which has been accurately analyzed is the olive oil. Its constituents were ascertained by Gay-Lussac and Thenard, by burning a determinate quantity of it, mixed with chlo- rate of potash. They are Hydrogen 13*? 60 Carbon 77*213 Oxygen 9*427 100 000 The above analysis is given without reference to the atomic theory, with which it does not well accord. 15. The constituents just stated for the fixed oils may be called their ultimate constituents. Besides these, by a pecu- liar mode of analysis, they mav be resolved into two dis- tinct substances, which may with propriety be called their Proximate proximate constituents. These substances were discovered constitu- by Chevreul in 1814, as the proximate constituents of all kinds of animal fat; and in the succeeding year, Braconnot proved that a similar constitution obtained in the fixed oils of the vegetable kingdom. An account of these two sub- stances, under the names of stearin and ela'in, appellations stearin and assigned to them by Chevreul, will form a very proper se- i'ixed oils useful in pharmacy. Ultimate constitu- ents of fix- ed oils. puts of all fixed oils are t» o pe culiar sub- stances, called ela'in quel to the present section on the fixed oils. FIXED OILS. 421 Chap.V. I. OF STEARIN.* 1. This substance may be obtained by treating purified Stearim^ hogslard wth boiling alcohol. As the alcohol cools, a white e°b° crystalline substance is deposited, which is stearin. Chevreul. 2. Hogslard, being an animal fat, is composed, as has been already mentioned, of sUarin and elii'n; the former is soluble in boiling alcohol only; the latter, in alcohol whether hot or cold. It is on this account, that the stearin is obtain- ed in a separate state by the process just given; for the alcohol, upon cooling, is no longer able to hold in solution the stearin, which is therefore deposited, while the ela'in still remains in solution. 3. The above method for obtaining stearin is that of Method of Chevreul. Braconnot employs a simpler one. It consists in Braconnot. this: if the oil to be analyztd is in a liquid state, it is first congealed, and afterwards subjected to strong pressure be- tween the folds of blotting paper. The ela'in is imbibed by the paper, while the stearin remains behind pure. The con- crete oils may be subjected to pressure at once, without any previous preparation. 4. Suarin, when thus obtained, is a white, brittle sub-Properties stance, having some resemblance to wax. When pure, it is of stearin. destitute of smell or taste. It does not alter the colour of vegetable blues. It is somewhat different in its properties, according to the animal oil from which it may be obtained. II. OF ELAIN.t 1. Chevreul's process for obtaining ela'in is to dissolve Elam; pro-' tallow of some kind in boiling alcohol, to allow the stearin cess for ob- to precipitate by cooling, and to distil the alcohol fromtMning l1, the ela'in. Braconnot obtains it from the paper which has imbibed it in his method by pressure. The paper is soaked in water and subjected to pressure. The pure ela'in is there- by forced out. 2. Ela'in has very much the appearance of a vegetable oil. Its proper- It differs considerably, according to the tallow or oil fromties- which it may be separated. Sometimes it is obtained desti- tute of smell or colour; but more usually it has both, owing to the presence of foreign substances. The properties of stearin and ela'in having thus been briefly given, it may be worth yvhile to state the propor- • From 4- f "icofluonc acid. 5. Chlorocyanic acid. 6. Sulphocyanic acid. 7. Ferrocyanic acid. 5. Acids, in which Oxygen ^ 1. Uric acid. % Purpuric acld. 3. Gallic acid. 4. Formic acid. 5. Oxalic acid, 6. Sorbic acid. 7. Succinic acid. 8. Acetic acid. 9. Tartaric acid, 10. Benzoic acid. 11. Saclactic acid. j w1? . wnicn Ux3'gen l »• saclactic acu and Hydrogen are botbV 12. Citric acid Present. 13. Mellitic acid If' euphoric acid. 15. Malic acid. 16. Lactic acid. 17. Pyrotartaric acid. 18. Moroxylic acid. 19. Suberic acid. 20. Laccic acid. 21. Kinic acid. 22. Zumic acid. .23. Bol«tic acid. f This division of com- j pound ponderable bodies J is tieaied of in as many "S classes, as there are sa- lifiable bases, formed Urom distinct radicals. f 1. Alcohol. 2. Ethers. J 3. Volatile oils. *y 4. Fixed oils. I 5. Spermaceti. V. 6. Soaps. C 427 ] BOOK II. OF IMPONDERABLE BODIES. Under this title are included those substances, which book ii cannot be weighed, or exhibited in separate and distinct:------*" masses. These bodies may be enumerated as light, heat. able'b«iUs, electricity and magnetism. Light and heat only wifl bedefined and noticed in this work. They will be treated of in the two ted!"16™ following chapters. CHAPTER I. OF LIGHT. 1. It is intended to give a very cursory sketch only of the properties of light. This substance is not legitimately an object of chemical imestigations, although it is concern- ed in a number of chemical phenomena. 2. Light is generally considered to be a substance, com- Properties posed of inconceivably small particles, constantly separating of light. from luminous bodies, and which, by entering the eye, ex- cite the phenomena of vision. Some philosophers, however, consider light to consist in the undulations of a subtle fluid, filling all space, which, in a quiescent state, has not the poyver of exciting vision or of rendering bodies luminous. 3. The most distinctive property of light is its amazing It m0Tes velocity. It has been demonstrated by Roemer, a Danish with great astronomer, that it moves at the rate of 200,000 miles in a ve,ocity- second. 4. Light moves constantly in straight lines. It may be it changes frequently made to change its direction; but every new '^8 (lirec- direction will be a straight line. As long as a ray of light Spring™ remains in the same medium, its direction remains thenewmeJi- same; but if it pass obliquely from a rarer to a denser um? niis m dium, it takes a new direction approaching a perpendi- refracted. cular line, drawn from the surface of the new medium, at th^ angle of incidence of the ray. But if the ray pass from a denser to a rarer medium, it is turned in a new direction 428 IMPONDERABLE BODIES. Book II. Reflection described. Transpa- rency ex- plained. from the perpendicular. This change in the direction of light, when it passes from one medium to another, is called its refraction. When a ray of light, passing through one medium, strikes against the surface of another yvith a cer- tain obliquity of direction, it is turned back again in the same medium. This turning back of a ray in one medium, in consequence of its impinging on the surface of another medium, is called its reflection. The angle, in yvhich the ray falls upon the neyv medium, is called the angle of inci- dence; and the angle, which it makes with the same medium after it has assumed its new direction, is called the angle of reflection. The angles of incidence and reflection are ahvays found to be equal. 5. Light, by falling upon bodies whose particles are uniformly arranged, gives rise to what is called their transparency. When light falls upon a transparent body, it passes through it in all directions without impediment. Rays of light excite the vision of the objects from yvhich they proceed, after having passed through such bodies, nearly as well as when passing in open space. It is probable, that light is enabled to pass through transparent bodies, without restraint, in consequence of its being attracted equally on all sides, thereby not being turned out of its Causes of straight course. On the other hand, bodies are opaque, opacity and when the rays of light which enter their surfaces are irre- 8' gularly attracted by their particles, whereby they are im- peded and ultimately arrested in their progress. Bodies are semi-transparent, when some rays pass through them, while others are reflected from different points of their interior substance. 6. Light, as it is generally seen, is compounded of seven different kinds of light. It may be decomposed by pounded'of being passed through a triangular prism of glass. It thereby seven kinds assumes the form of an oblong image, usually called spec- tary neht" trum> composed of seven different coloured portions, each portion produced by a different ray of light. This decompo- sition takes place in consequence of a difference in the re- frangibility of the component parts of light. Each part, in consequence of this difference, is turned off in a direction peculiar to itself, and consequently located by itself, when arrested by the interposition of an opaque surface. These seven component parts of light, according to the colour which each excites in vision, are called red, orange, yellow, green, blue, indigo or violet light. They are enumerated in the order in which they are arranged in the spectrum, which is also the order of their refrangibility; the red light being the least, and the violet the most refrangible. parency. Light, as usually seen, com- LIGHT. 429 7. When a compound ray of light falls upon a body, all Chap. i. its elementary rays may be absorbed or reflected, or part Coiour ex! of them may be absorbed and part reflected. When a body plained. absorbs the whole ray of light, its colour is said to be black; but, in reality, it ought to be snid to have no colour, as it makes not an absolute but a negative impression on the optic nerve. When a body is white, it is in consequence of the whole ray being reflected from its surface, and en- tering the eye. When a body absorbs some parts of the compound ray and reflects other parts, its colour is pro- duced by those rays, which are reflected. If the blue ray be reflected, while the rest are absorbed, the body appears blue; if the green ray, the body appears green; and if two or more rays are reflected, while the rest are absorbed, the body so reflecting will be of a colour compounded of the colour of such rays. 8. The absence or presence of light produces very re- Effects of markable effects upon different bodies. Plants, in the open,ifhton , D-f»nts &nd air exposed to the light of day, generally reflect the green metallic ray of light, or are green; but if placed in a dark room, oxides. they acquire the property of reflecting the whole ray of light without decomposition, or, in other words, they be- come white. Similar changes take place in the ray reflected from various metallic oxides, in consequence of an exposure to an increased quantity of light. 9. The changes, in the colour of metallic oxides by light, Light sepa- are attended by a deoxidizement of these compounds. It j^f^" is not known in what yvay this chemical decomposition the latter. takes place; but it is ascertained, that, of the different co- lorific rays already mentioned, the violet has the greatest deoxidizing poyver; and that this power decreases gradually towards the red end of the spectrum. It appears by some late experiments, that the deoxidizing poyver is possessed, to a still greater extent, by some rays which are found a little beyond the violet end of the spectrum. These rays are not colorific, and, from their most remarkable property, have been called deoxidizing rays. 10. The sources from which light is emitted are very Sources of various. The principal ones are the sun, burning bodies, "'S01- and heated bodies. The rays of the sun appear to be com- pounded of rays of light and rays of heat. The sun is incomparably the most abundant source of light. Bodies undergoing combustion always emit light as well as heat. Burning bodies, next to the sun, are the most abundant sources of light. All bodies, yvhich do not previously un- dergo volatilization or combustion, upon being heated to a certain temperature, become luminous, or, in other words, 430 IMPONDERABLE BODIES BooK D- emit light. Thus iron, upon ignition, becomes first red and afterwards white hot. To this rule, however, there is one exception; the gases do not become luminous, in any heat to which they have as yet been exposed. CHAPTER II. OF HEAT. (Chemical name, Caloric.) The word The word heat is used in two different acceptations. !*ea*j_ufed When a person speaks of feeling heat, he alludes to the accepta- sensation produced by an accession of heat to some part of tions. his body. Heat, therefore, when spoken of with reference to sensations, is always a relative term. The sensation of cold may be said, in a philosophical sense, to be a sensation of heat; that is, a sensation of caloric or the matter of heat passing out of the body. Hence it appears, that the matter of heat is the cause of the sensation both of heat and cold; and that the difference in the impression which it produces depends aione upon the direction in which its motion is established with respect to the sentient body. Its mean- In this chapter, it is the matter of heat, or caloric which ing in a js the subject of consideration. The reader will, therefore, sense. take care not to confound the matter of heat yvith its effects on sentient bodies. The sub- The subject of caloric will be treated of under the six jectofheat, following heads: treated of _ .r,, ° r , under six !• *■he nature of caloric. heads. 2. The agencies, by which caloric is put in motion. 3. The different ways in which caloric tends to a state of rest, after having been put in motion. 4. The relative quantities, in which heat in a state of rest exists in bodies. 5. The changes produced by caloric upon bodies. 6. The different instruments in common use for measuring the intensity of heat. These heads will form the titles of the six following sections. SECTION I. OF THE NATURE OF CALORIC. Two opin- *• Heat is considered by almost all the philosophers of the ions enter- present day to be a substance, composed of inconceivably tamedof smari particles. Count Rumford and Sir H. Davy, how- CALORIC. 431 ever, are of opinion, that heat depends upon a peculiar Chap. ii. motion, and is not owing to the presence of a subtle fluid, ^TnatuT" which chemists have designated by the name of caloric. of caloric 2. The opinion, that the phenomena of heat depend upon a peculiar fluid, and not upon a peculiar motion betyveen the particles of bodies exhibiting such phenomena, will be adopted in the present chapter. But whether heat be an attribute of matter or a substance, the facts detailed in the following sections are not the less certain. SECTION II. OF THE AGENCIES BY WHICH CALORIC IS PUT IN MOTION. 1. All the effects which caloric produces depend direct- All theef- ly or indirectly upon its motion. H.nce the account of the fr.'f °fca" agencies by which it is put in motion is exceedingly im- pen attrI- 7. 1 here are many familiar instances of the agency of tion and condensation in producing a distributable excess of caloric cJjemieal in bodies. A piece of iron, by repeated blows of a hammer, E anse * may be made to become red-hot. This is a case of conden-of adistri- sation, produced by percussion; and that this condensation b,,tab,.ee!c" i .. l • r i • ri • i . . cess ol ealo- lessens the capacity at the iron for heat, is proved by the ric pi-odu- fact, that a piece of iron once hammered until it becomes ofce<1 by con- a maximum of density cannot be again heated by this ensatlon- means, unless it be previously exposed to a red heat, and thereby lessened in density and increased in capacity. The condensation of air is capable of disengaging a sufficient excess of distributable heat to produce combustion. Thus, if a piece of tinder be placed in the bottom of a syringe, and the air contained in the barrel of this instrument be sud- denly compressed upon it, by quickly urging down the pis- ton, sufficient distributable heat is evolved to set the tinder on fire. The collision of the flint and steel may be mention- ed under the head of condensation. By the stroke, a piece of the steel is driven off in a condensed state, which is thereby heated sufficiently to take fire in the air. The col- lision of two flints produces a distributable excess of heat in the same manner; but there is this difference in the result, that the piece of flint driven off does not take fire, being incapable of combustion. 8. If the question be asked, why, by condensation, the capacity of a body for heat is decreased, it may be answer- ed, that it probably depends upon the nearer approach of the particles co'mposing a body. This approach increases the repulsive poyver of the contained caloric, which is thereby made to fly off in the form of distributable heat, 9. Attrition or friction is capable of producing a distri- Examples butable excess of caloric in bodies; but the manner in yvhich of attrition it produces this excess has never been satisfactorily ex-tjveofa plained. There is found to be no condensation or chemical distributa- action produced, which might occasion a decrease of capa- 0feCajori*9 city. It was certain experiments, made to ascertain the quantity of distributable heat produced by friction, yvhich induced Count Rumford to deny the existence of heat as a substance; and to conclude that all the effects attributed to the matter of heat depended entirely upon peculiar motions. 3 I 434 IMPONDERABLE BODIES. BookH Distributable heat produced by friction must therefore be considered, in the present state of knowledge, as an excep- tion tiom the general position, that heat is throwu into a distributable state by those causes only, which decrease the capacities of bodies. Combus- 10. Combustion is by far the most usual means, employed heat into a D>' man> for putting caloric in a distributable state. This distributa- process appears, most evidently, to be one, in which two estate, bodies by their union form a third, which has a capacity for heat much less than that of either of its constituents; and hence the appearance of heat in a distributable state. This theory does not explain the appearance of light in combustion: but is it not probable, that bodies may have different capacities for light as well as for heat; and that light, during combustion, may appear in cons' quence of the diminished capacity of the product for this fluid? 11. The action which is going on in the sun is the cause of putting a very large quantity of heat in the distri- butable state. Philosophers know nothing of the kind of action going on in this great luminary; but, judging from the effects it produces, there is good reason for believing, that it is analogous to that which takes place in combustion, if not absolutely the same. Combustion 12. Having now mentioned combustion, as one of the explained means by which heat may be thrown into a distributable in various state; it is next proper to give a short account of the most waJ«- remarkable theories, which have been, from time to time, invented to explain this wonderful process. StshPsthe- 13. All the theories, invented before the time of Stahl, ory, the appear to have been crude and unsatisfactory. The theory itnportance of Stahl yvas simply this: all combustible bodies agree in It supposed containing a peculiar substance, to yvhich they owe their an inflam- combustibility. This substance, Stahl denominated phlogis- ™Hb,e'>r,n* ton. When a body burns, nothing takes place but the se- parate from paration of phlogiston; and the light and heat which ap- h!u\burning pear are mere properties of the phlogiston, when in a state of motion. The theory of Stahl was called the phlogistic theory. 14. The phlogistic theory remained for a long time to be almost universally admitted, as well because it was easily understood, as that its ingenious author supported it by many experiments and apparent proofs. Suhi's the- 15. The first important modification, which the Stahlian ory^modifi- theory received, yvas that given to it by Priestley. This Priestley, chemist found, that, when a combustible is allowed to burn until it becomes extinguished in a portion of air in a close vessel, the air is altered in its properties, and is no longer CALORIC. 435 fit to support this process. To account for the change pro- Chap. n. duced in air by combustion, he supposed, that the phlogis- ton of the combustible united with the oxygen of the air, in which the combustible was burnt. Under the influence of this theory, he called oxygen gas, dephlogisticated air; that is, air, which, by reason of its not containing phlogiston, is fit to attract phlogiston from combustibles, or, in other words, to cause them to burn. On the other hand, air, which had been altered by combustion, he called phlogisticated air; that is, air saturated with phlogiston, derived from burning bodies during their combustion. Priestley's modification of Stahl's Priestley's theory changed entirely the leading features of the latter. a"»d Stahl's Stahl's phlogiston produced the light and heat of combus- compared. tion: Priestley's phlogiston was no sooner separated from the combustible than it combim d with the air which sup- ported the combustion. Stahl's theory required for combus- tion merely a combustible and a sufficient heat to com- mence the separation of the phlogiston: Priestley's theory, besides these prerequisites, made the presence of some body necessary to attract the phlogiston from the combus- tible. In Stahl's theory, one set of bodies only were con- cerned, namely bodies containing phlogiston: in Priestley's theory, besides such bodies, a set to attract phlogiston from the combustible were also necessary. According to Priest- ley, a combustible became dephlogisticated by being burnt; while, on the other hand, his supporters of co nbustion were phlogisticated, by having combustible bodies burnt in them. 16. Priestley's theory appeared to leave unaccounted for Priestley's the appearance of light and heat during combustion. This th*',r> ,,,d not -iccouiit* point Stahl attempted to explain by referring these princi- for the ap- ples to the motion of the separated phlogiston. Dr. Craw- pearance of ford, in order to remove this difficulty, made an addition nfat fn" to Priestley's theory, by supposing, that, when the phlogis- combustion. ton of a burning body united with the air by which the combustion was carried on, at the same moment there is separated from such air a quantity of light and heat. 17* The theory, as amended by Dr. Crawford, was cer- tainly more satisfactory, as it accounted for the appearance of the light and heat of combustion; but still it contended for the existence of a substance entirely hypothetical. Phlo- giston yvas supposed to exist by Stahl, only because the supposition yvas convenient for him: no succeeding chemist had proved its existence by experiment. 18. To remove this objection, Kirwan substituted hydro- gen for phlogiston, and attributed to it almost every agency, yvhich had been previously assigned to the inflammable principle. He supposed, that every combustible contained 436 IMPONDERABLE HODIES. Book il hydrogen, and that, during combustion, hydrogen separated ""from the combustible and combined with the oxygen of the air. Lavoisier's 19. About the time that the Stahlian theory received its overturned *ast Modification from Kirwan, Lavoisier made known to the Stah- the world his discoveries; by which he was supposed to iiTaifits^ P1"0*'^ t^iat m every case of combustion, oxygen combines forms. with the burning body, and separates from the light and heat previously combined with it yvhen in the gaseous state. The product is incombustible, since it is entirely saturated with oxygen, and is therefore incapable of occasioning the emissiou of more light or heat, by a further combination with this principle. 20. The theory of Lavoisier, called the antiphlogistic theory, very soon overturned the modified Stahlian doctrine, which had been previously almost universally admitted. Chemists yvith very few exceptions adopted the new doc- trine, and had no longer recourse to the hypothetical sub- stance phlogiston to explain the process of combustion. Lavoisier- 21. The theory of Lavoisier, although true in the main, urn theory nevertheless has required considerable modifications to reu- butone der it consistent with the light of more modern discoveries. supporter According to Lavoisier, oxygen is the only body which is of combus- iir I ..• • l j r tion; name- capable ot supporting combustion, or, in other words, ot ly oxygen: separating from its light and heat, in the act of combining ew-r'bave"'"w *tn a combustible. Subsequent experiments, however, been disco- have proved this position to be untrue; for it has been vered. found, that several bodies, besides oxygen, combine with combustibles in such a manner as to exhibit the phenomena of combustion. Hence, therefore, instead of there being but one supporter of combustion as Lavoisier supposed, there are at least three, if not four. The discovery of a plurality of supporters does not, however, destroy the theory of Lavoisier, it merely enlarges its boundaries. 22. The reader has already been made acquainted with the division of chemical bodies, with reference to combus- tion, into supporters of combustion, incombustibles, and combustibles. The foundation of this division is very intel- ligible and need not be explained here. Some of the 23, According to the theory of Lavoisier, the whole of th^L,8 °f' ^e ^8^1; and heat, appearing in combustion, is furnished by sierian the- the supporter. Some very valid objections have been ory, object- brought against this supposition by Dr. Thomson. This ed tob\ Dr. . °. , ° , , ,rr , J . c , i l • Thomson, chemist has observed, that the quantity ot heat evolved in combustion is always greater, the greater the proportional qu ntity of a supporter which combines with a combustible; but tha,t the reverse of this is the case yvith regard to the CALORIC. 437 light emitted. For example, the heat evolved by the com- Chap. II. bustion of hydrogen, carbon, and phosphorus is greater, in proportion as the quantities of oxygen which they consume are greater; but the light evolved in the same process is greater where the heat is less. It is on this account, that Dr. Thomson thinks it probable, that the light which appears in combustion is derived from the combustible, while the supporter furnishes the heat. There are several circum- stances which make this opinion very plausible, but it is not less certain that some others militate against it. 24. After all, the doctrines of combustion, as generally Doctrines received, do not appear to be entirely confirmed by more of combus- recent investigations. During certain combinations of com- seuiecTby bustibles with each other, both light and h at are emitted; re.entdis- and therefore the chemical action which takes place cannotcovenes" be distinguished, in a philosophical sense, from combustion. This is the case in the combination of potassium or sodium with sulphur. During the combination of sulphur and cop- per filings, there is so much heat evolved, that the com- pound becomes red-hot, or, in other words, luminous. Cyanogen gas, formed of azote and carbon, an incombus- tible and a combustible, appears not only to be combustible, but also a supporter of combustion; for it burns in air, the products being carbonic acid and azote, and supports the combustion of potassium, which absorbs it without decom- position. Hence the cyanodide of potassium, whose ultimate constituents are two combustibles and one incombustible, is nevertheless a product of combustion. 25. It thus appears pretty evident, that the facts at pre- The facts sent knoyvn relating to combustion cannot be arranged upon connected principles founded on general analogies. Chemists have dis- JJJeM*re- covered so many gradations in chemical action, attended by fusetoyield the emission of light and heat, from the most intense, as $ general occurs in strongly marked cases of combustion, to that-ation. which is attended with but a feeble emission of these prin- ciples, that it has been difficult to determine yvhat chemical actions are combustions and what are not. The neyv disco- veries, however, seem to make it necessary to distinguish those chemical actions which are attended with flame, from those attended by the emission of light and heat without flame. 26. Upon the whole, in the present state of knowledge Difficult on combustion, it does not appear expedient to attempt to of the sub- settle any general principles to explain the process. All that-'601, can be safely asserted on .the subject is, that it is chemical action attended with the emission of light and heat. The Defects of distinction of supporter of combustion and combustible the Sua? 438 IMPONDERABLE BODniS. Book ii. cannot properly be preserved; for by possibility every sup- dirision of"Porter may on some occasion become a combustible, and bodies, every combustible a supporter. How then is the chemist to oombustion. ascerta*n which are combustibles and which supporters? In a philosophical sense, when oxygen and hydrogen unite, the oxygen may be said, with equal propriety, to burn in the hydrogen, as the hydrogen in the oxygen; for, yvithout doubt, the combustion of these gas'-s might be effected by causing a small stream of oxygen, raised to the proper temperature, to pass into an atmosphere of hydrogen. Un- der such circumstances, the oxygen might be said to burn in the hydrogen; but the process is in no wise different trom that of burning hydrogen in oxygen; since the union takes place only where the gases are in contact. Again, a body may be incombustible with reference to oxygen, but how is the chemist to be certain, that it is so with reference to every other substance? Although it may not form a com- bination yvith oxygen with the emission of light and heat, is it impossible that it should combine with some other body wLh the emission of these principles? No body can, there- fore, be said to be necessarily incombustible. 27. Whatever theory is adopted respecting combustion, this position may be assumed as certain, that, in every case of this process, quiescent heat is changed into distributable heat; or, in other words, the product is not capable of holding in a quiescent state as much heat, comparatively with other bodies, as its constituents were before undergo- ing the process. Now this peculiar alteration in bodies im- plies a decrease in their capacity. Consequently the products of all combustions must possess a less capacity for heat than the mean capacity of their constituents. 28. The consideration of combustion, as a cause of putting quiescent heat in a distributable state, being finished, the remaining causes, which have the same agency, will now be considered. Other che- 29. Other chemical combinations, besides those yvhich mical chan-are attended by combustion, throw quiescent heat into a combus- CS distributable state. These combinations generally take place don, put between liquids, but sometimes between gases. As a gene- beaTfn a* ra* ru^e* n mav ^e sa^' l^at l^e c°mP°und formed suffers a distribuu- decrease in density. Now this is what would naturally be bie state, expected to occur; since these mixtures suffer a decrease in capacity, as is evinced by their being incapable of holding as much heat in a quiescent state as their constituents se- parately. , Examples 30. As instances of chemical combinations, other than chemical combustions, in which quiescent heat is throyvn into a dis- changes. caloric. 439 tributable state, may be mentioned the combination of sul- Chap. II. phur c acid and water, of alcohol and water, or of ammonia- ~~ cal gas and hydrochloric (muriatic) acid gas. There are innumerable instances of this kind, occurring in almost every chemical change. 31. Before closing the account of the different means, by Electricity which quiescent heat is thrown into a distributable state, it Puts V***: * , • • to.* a -j -n cent heat in is proper to mention electricity. 1 his fluid, more especially moUon. when set in motion by means of the galvanic apparatus, is capable of putting, very suddenly, a great quantity of qui- escent heat in a distributable state, and of causing as in- tense a degree of heat as can be produced by any other means. It is not possible to explain this agency on the general principles of decreased capacity. It may therefore, like friction, be considered an exception to the position, heretofore laid down, that all agencies, which convert qui- escent heat into distributable heat, produce a decrease of capacity in the bodies upon which they act. 32. Having finished the account of the different ways, in which the quiescent heat of a body may be diminished and part of it converted into distributable heat, and thus com- pleted the history of one of the ways by which heat is put in motion; the other way, by which heat is disturbed from its quiescent state, comes next under consideration. 33. This other way depends upon an increase of capacity Heat is put in a body. After undergoing an increase of capacity, a body«" motion requires a larger share of quiescent heat, comparatively with quea^f8" that possessed by surrounding bodies. Hence part of the theincieai- caloric of surrounding bodies is put in motion, and thereby &£$££?* becomes distributable; but ultimately, by combining with the body whose capacity has been increased, it becomes quiescent. This motion continues, until the caloric has ad- justed itself in the body whose capacity has been increased and in surrounding bodies, in such quotas as to suit the new relation, which the capacity of the altered body bears to the capacities of surrounding bodies. In all such cases, cold is Cold al- produced; since the heat of surrounding bodies is first ren- wa^ £ene" dered distributable, and ultimately becomes quiescent in such cases. the body whose capacity has been increased, or, in other words, all surrounding bodies yield up part of their caloric, which passes into the body whose capacity has been in- creased. 34. All the causes of increased capacity of bodies, or, in Causes of other words, of the production of cold, appear to be chemi- "nore^sed cal. Evaporation is a very powerful means of producing bodTeTJre1 cold, and acts by increasing capacity. Many chemical com- always che- binations result in an increase of capacity in the compound mical' 440 IMPONDERABLE BODIES. Book ii. formed, and consequently produce cold. These consist ge- "" nerally of different kinds of salts mixed with water, and are called fi'igorinc mixtures. SECTION III. OF THE DIFFERENT WAYS, IN WHICH CALORIC TENDS TO A STATE OF REST, AFTER HAVING BEEN PUT IN MOTION. 1. Having in the foregoing section explaim d the different ways in vhich caloric is put in motion, the subject passes, by a natural transition, to the consideration of the different Bodies are modes in which it tends to a state of rest. And here it will often heat be proper to remark, that it is from the tendency, which tendency of distributable heat has to assume a state of rest, that bodies caloric to are most generally heated. In the last section, it has been stateof * shown how heat is primarily set in motion, so as to become rest. a heating cause; but an excess of distributable heat may be accumulated in many bodies, in which it is not primaraly set in motion; and this depends upon no other cause than the tendency yvhich heat, in the distributable state, has to assume a quiescent state. Thus combustion is a primary cause of putting heat in a distributable state; but there is no inherent poyver in a stone to produce the same effect. Nevertheless, if a stone be put in the fire, the distributa- ble heat of the latter, in its tendency to rest, first meets with the stone and heats it; the fire is constantly parting with heat to the stone, and the stone to the hearth upon which it rests, or to the air yvhich surrounds it. It is in this way, that bodies, which cannot originate a distributable excess of heat, are heated during the cooling process of those which can. Ueatinmo- 2* The P"ncipaJ ways in which heat tends to a state ot tioen tends' rest are by radiation and conduction. The account, there- to a state of fore^ Qf the manner in which heat is radiated and conducted Sio^and' will comprise all that is necessary to be said in this section. conduction. . „ I. OF THE RADIATION OF HEAT. Radiation 1. When a body is made to contain by any means a dis- expiained. tributable excess of caloric, one way in which this excess tends to a state of rest is by passing off in right lines in all directions from its surface. This peculiar manner of passing off of caloric from a body is called radiation. The a. 2. From the experiments of Leslie, it appears, that the mount of quantity of heat distributed by radiation depends almost b|?tPven. entirely upon the nature of the radiating surface. I his phi- CALORIC. 441 losopher filled with boiling water a thin globe of bright tin, chap. ii. and found, that the water took 156 minutes to cool down halfationde. way from its original temperature, to that of the room in pends upon which the experiment was made. The same experiment be- t!?.e. nat"J'e , r . , , . . . , , , r . . "I the ladl- ing repeated with this variation only, that the tin globe was ating sur- covered with a thin coating of lampblack, the hot yvaterface- took but 81 minutes to cool to the same temperature. From this it was evident, that hot yvater in a tin globe cooled nearly twice as fast, when its surface was covered yvith a coating of lampblack, as when it yvas clean and bright. No- thing could exemplify more strongly the effect of surface in increasing radiation than this simple experiment. 3. Heat distributes itself, by radiation, in all directions Heat radt- from the surface of a hot body; but most copiously in a di- a*es in al1 rection perpendicular to the radiating surface. For exam- fronfsTrL pie, it was found by Leslie, that, when a tin canister, filled ces- with hot water, is presented without any obliquity to a re- flector, the effect is greatest, as ascertained by a thermome- ter placed in its focus, and that it becomes less and less in an oblique position, according to the degree of obliquity. 4. Leslie has found, that different substances differ very much in the radiating power of their surfaces. This he as- certained by applying different substances in succession to one side of a canister, filled yvith hot water and placed be- fore a reflector. The effect of each was measured by the degree of heat observed in the focus. The following are the principal results of these trials. Taking the radiating poyver of lampblack as 100, Radiating that of yvriting paper will be 98 power of of crown glass 90 ^Se, of ice 85 of tarnished lead 45 of clean lead 19 of polished iron 15 of tin plate 12 of gold, silver, or copper 12 5. From these experiments, it appears, that metals dis- tribute less heat by radiation than any of the bodies tried. The radiation, however, is influenced not only by the nature of the substance, but also by the nature of the surface in the same substance. In the foregoing statement, it is seen, that the radiation of clean lead is 19, yvhereas that of tarnished lead is as high as 45. The smoothness of the surface of a metal being destroyed increases its radiating power. Thus, if the side of a bright tin canister produce a radiation equal to 12 by rubbing it in one direction with fine sand paper, the ra- 3 K 442 IMPONDERABLE BODIES Book il diating effect will be increased to 22; but when rubbed in — the cross direction, the effect is somewhat diminished. 6. Radiating heat, when it falls upon different bodies, m.\\ be absorbed or reflected, or partly absorbed and partly reflected. The nature of the body and of the surface varies Absorbing vel7 much these circumstances. It has been found, that povei ot°a those bodies and surfaces, which have the greatest radiating rettijV-o- POWtr- have also tne greatest absorbing power. This is yvhat portionai, might have been expected; since it is reasonable, that the nectin^" same peculiarities, v>hich enable heat to pass out of a sur- power in- face in the greatest abundance, would also enable it to pass versely in# On the other hand, it has been found, that the worst ra- ai'^toTura-diating surfaces are the best reflecting surfaces; or, which dialing is the same thing, that the worst absorbing surfaces are best suited for reflecting. Radiating 7# RadjatinK cai0ric is capable of being refracted by neat may o «■ , • oil f be refract- transparent bodies, as well as of being reflected by surfaces, ed- and in this way, it may be very much concentrated, as well as by reflection. The radiating caloric, emitted by the sun, may be so concentrated by refraction, as to produce as pow- erful a heat as can be excited by any other means. Radiation 8. From the experiments of Leslie, it appears, that radia- takcs place tion can take place in elastic media only. In common cases, niediaSoniy. the medium is atmospheric air; but as far as his experi- ments have gone, radiation does not appear to be influenced by the particular elastic medium in which it occurs. It, how- ever, decreases in proportion to the rarefaction of the medi- um, and at different rates in different media. IL OF THE CONDUCTION OF HEAT. Conduction 1. If one end of a bar of iron, 20 inches long, be put in of heat ex- t^t fire^ jt jS some time before the other end experiences any emphfied; increase of heat> From this it is evident, that heat takes some time to travel through a bar of iron. This slow man- ner, in which heat distributes itself under the circumstances just stated, is called its conduction. 2. It is in this yvay that heat always distributes itself in solid bodies. In the same mode, it may be distributed through liquids and gases; but with far less celerity than by other means to be explained presently. and ex- 3. The explanation of the conduction of heat appears to plained. be this: whatever quantity of heat is absorbed by the exterior stratum of particles exposed to the heating cause, a propor- tion of it is immediately transferred to the stratum under- neath: and whatever quantity of heat is thus transferred to a substratum, a proportion of it is immediately transferred to It has its li- the next stratum, and so on for any number of strata within mit- a certain limit. These transfers may be said to depend upon CALORIC. 443 the affinity of the different strata for caloric; but, be this as Chap.ii. it may, it certainly takes place upon the same general prin- ciples, that distributable heat will combine yvith all bodies, yvhose quotas of caloric are relatively defective. 4. The limit, which obtains yvith regard to the conducting This limit power of bodies, depends upon the quantity of caloric, with ^"{J, which they will combine before they change their state as to quantity of aggregation. Every dose of caloric absorbed by a conduct- ^j1^ bo ing body, excepting that yvhich changes its state, causes an Xhus, if any quantity of distributable heat adjusts itself, in a state of rest, between any tyvo bodies, in proportions as tyvo to one; then that body, yvhich has the double share, is CALORIC. 445 said to be double the capacity of the other. The capacity Chap, il of bodies for heat is sometimes called their specific caloric. 5. It is reasonable to suppose, that the relative quantities And these of heat in different bodies are indicated by their capacities; capacities since it is probable, that distributable heat would adjust it- measures of self in the same proportional quantities between bodies, to- the relative tally deprived of their caloric, as at any particular tempera- ofheatcon- ture. It must not be denied, however, that some facts are tained in rather unfavourable to this supposition. bodleS- 6. In many books of chemistry, a good deal is said to ex- Equality of plain, why bodies assume an equality of temperature; but turede-" the explanation of this fact can be nothing else than to give pends upon the reasons, why heat in a state of motion tends to a state of" rest'of'heat rest. Nothing else is meant by equality of temperature be- between tween any two bodies, than that the heat which they contain bodies- is not impelled to move from either to the other. It would appear, that the general principle, upon which caloric moves after having been set in motion, is its being unequally press- ed in different directions; and that this motion continues, until its cause, namely the unequal pressure, ceases. SECTION V. OF THE CHANGES WHICH CALORIC PRODUCES IN BODIES. These effects may be arranged under three heads. l.Changesby Changes in bulk. 2. Changes in state. 3. Chemical changes, calorie are, changes in I. OF CHANGES IN BULK. *>uik, in 1. As a general law, it may be stated, that an accession of chemical heat to a body increases its bulk; but to this law there are chanSes- several exceptions, which will be stated hereafter. Caloric in- 2. The expansion produced by a given quantum of heat is fr^?se? ^he very different in solids, liquids and gases. As a general dies. rule, in the gases it is greatest, in liquids much less, and in solids least of all. All gases suffer the same expansion by the same degree of heat, supposing them placed in like cir- cumstances. The expansion of liquids is not found to be uniform. It has been ascertained, however, that the lower their boiling point, the greater is the expansion produced by a given increment of heat. Thus the boiling point of alcohol is low, that of water higher, and that of mercury higher than either; and the expansion, produced by any given in- crease of temperature in these three bodies, is greatest in the alcohol, less in the water, and least of all in the mercu- ry. It has also been found, that the rate of the expansion in- 446 IMPONDERABLE BODIES. Book II. Exceptions to the law of expan- sion by heat. Water an exception. Alumina, another ex- ception. creases, the nearer liquids are to the boiling point. The ex- pansion of solid bodies by heat is so very small, as to re- quire very nice instruments to measure it; but as far as ex- periments have gone, it appears to be equable. 3. The exceptions to the general law of expansion by heat are, water below a certain temperature, alumina or clay, and certain substances in the act of solidification. 4. When water in the liquid state, at any temperature be- low 40°, is exposed to heat, it gradually contracts with every increment of heat, until its temperature reaches 40°, after which it expands by every addition of heat, until it reaches the boiling point, when it changes its state. Hence at 40Q and above it, heat produces its usual effect on water; but below that temperature, it contracts this liquid. So that water is at a maximum of density at the temperature of 40°; and if it be heated above or cooled below that temperature, it is expanded. 5. The final cause of water having a maximum of density above the freezing point, would seem to be to put a limit to the consolidation of this liquid in the winter season. When yvater in rivers, above the temperature of 40°, is exposed to causes which abstract its heat, they operate upon a stratum on the surface, and, by the abstraction of its heat, render it speci- fically heavier than the water underneath; it therefore sinks to the bottom. By this means, a neyv stratum is exposed to the operation of the cold, and sinks in its turn. This exposure to cold of successive strata continues, until the yvhole of the water has acquired the temperature of 40°, when it ceases. It ceases, because the uppermost stratum, being at 40°, in- stead of being contracted by an abstraction of its heat, is in fact expanded, and therefore cannot sink. Hence then the cold acts continually upon the same stratum, which remains im- moveably on the top,and cools it down to 32°, when it freezes. If there were no maximum of density in yvater above the freezing point, the successive presentation of strata to the cooling cause would continue to take place, yvith regard to the yvater in rivers, until the yvhole liquid, from top to bottom, yvould be cooled down to the freezing point; at which pe- riod, the whole would be liable to freeze into a solid mass of ice. Thus it would appear, that water yvas formed an excep- tion, to the general law of the expansion of liquids by heat, by the great Author of nature, to guard against the calami- tous consequences to man, which would result upon the freezing of rivers in the winter into one solid mass of ice to the bottom. 6. Alumina seems to constitute an exception to the gene- ral law of the expansion of bodies by heat. This earthy base CALORIC. 447 undergoes a diminution of its bulk by exposure to heat. Chap. II. This diminution, at low temperatures, appears to depend upon ~ the dissipation of moisture. But at high ones, it takes place also, without any sensible loss of weight, and therefore can- not be attributed to this cause. At high temperatures, it pro- bably contracts in consequence of its particles being urged into closer contact, so as to leave no interstices. It is not unlikely, that after fusion it may expand by heat as other bodies. 7. Although several substances expand upon freezing, Bodies, and seem to be exceptions to the general law under consi- w|>'chcrys- . * » /• i . • «• t&iiizt? upon deration, yet upon a nearer view ot the subject, perhaps, the cooling, ex- reason of the apparent exception may be explained upon differ- par- ent principles, without interfering with the general law. All the bodies, which expand under such circumstances, are such as assume the crystalline form. May it not reasonably be supposed, that in crystallization their particles may arrange themselves, so as not accurately to fill space; and if so, the particles themselves might be diminished in bulk, while their aggregate, including the interstices, would take up more bulk than at first. 8. The most remarkable instances of this kind of expan- Instances of sion occur in the congelation of water, and during the consoli- fxparnsl0n. dation of several of the metals. The force, with which yvater liLtion* expands in the act of freezing, has been ascertained to be very great. Bombs, filled with water and plugged, have been known to be burst asunder on being exposed to a hard frost, in consequence of the freezing of the contained water. Of all the metals tried with a view to this subject, but three were found to expand upon solidification, namely, cast iron, bismuth and antimony. 9. In all cases, in yvhich liquids, in becoming solid, assume the crystalline form, the change of state is accompanied by expansion; on the other hand, when the change takes place yvithout being attended by any regularity of arrangement in the particles of a body, contraction is the consequence. In- stances of the latter kind are furnished in the congelation of oils, and of some of the metals, particularly mercury. This latter metal is found to lose ?Ld of its bulk in the act of congelation. II. OF CHANGES OF STATE PRODUGED BY CALORIC. 1. All bodies, as far as they are known, occur in one of Bodies oe- the three following states, as solids, as liquids, or as elastic c.ur a?s°- fluids or gases; nevertheless, in yvhichsoever state they occur, or Mses^5' they are all capable or presumed to be capable to assume the other two, by the addition or subtraction of heat. Thus 448 IMPONDERABLE BODIES Book II. sulphur at common temperatures is in the solid state; but Some b~ when heated to the tempi r.iture of 218°, it becomes liquid, dies may be anc[ at a neat Qe about 570°, it becomes an elastic fluid or mane to as- . . T .. . , , sume the gas. Again, water at ordinary temperatures is a liquid; hut three when heated to 212°, it becomes an elastic vapour, and when cooled to 32°, a solid in the form of ice. G:*ses, at common temperatures, are not susceptible of becoming solid by an abstraction of heat; one of them, however, (ammoniacal gas) is capable of being condensed into a liquid, by a cold of — 45. Hence the presumption is, that every species ot air might be condensed into a solid, if chemists had it in their poyver to produce a sufficient degree of artificial cold. 2. When solids are converted into liquids by an addition of heat, the change takes place either instantaneously or gradually; and there appears to be a good deal of difference in the manner, in which the liquefaction is produced in these diff rent ways. It begins to occur, in all common cases, when the solid body contains a certain quantum of heat, or, in other words, is of a particular temperature. Water, 3. Water, in common cases, is converted into ice at the converted temperature of 32°; but, by peculiar management, it may be at 32°; but cooled considerably below this temperature without losing may be its liquid form. This peculiar management consists in low that6 having the water perfectly pure and free from air, and in point with- exposing it to a gradually decreasing temperature. Under hsVquid8 sucn circumstances, it may be cooled down to the tempera- form, ture of 22° without freezing; but if a small piece of ice be When it thrown into it, or if it be made to take on a tremulous mo- freezes it *% rises to32°. tion, part of it suddenly freezes, and the temperature of the whole immediately rises to the freezing point. Inferences 4. The facts stated in the foregoing paragraph prove, tobe drawn that, when water cooled down below the freezing point is facts.the8C made to freeze, the part frozen, at the moment of its so- lidification, gives out sufficient heat to raise itself, and the remainder of the yvater, yet in the liquid state, to the tempe- rature of 32°. Hence the general fact may be deduced, that, although the abstraction of heat puts yvater in a condition to solidify, yet, in the act of freezing, heat is given out, not as the cause but as the effect of this act; or, in other yvords, part of the quiescent heat of yvater is converted into dis- tributable heat, by the energy of the power yvhich induces its congelation. Ice, during 5. If a piece of ice be brought into a warm room, the melting, re-quiescent heat Qf surrounding bodies is thrown into a dis- ceives heat, ^ ., ,, .. ." . •,••.. but no in- tnbutable state, in its tendency to give the ice its proper crease of quota of caloric. The caloric, however, yvhich the ice re- tempera- cejveSj js not distributable to bodies at the temperature of caloric. 449 32°, in other words, does not warm the ice; but combines Chap.ii. with it and converts it into water- As soon as all the ice is in this way dissolved, the water obtained is exactly of the same temperature yvith that of the ice, from which it was formed. But as it has been receiving a large share of heat during its formation, this inference may be fairly drawn, that, when caloric is in a state of rest with respect to yvater and ice, water contains a larger quantity of caloric than ice; or, to express the same idea in other words, when ice lique- fies, it combines with heat in such a way as to render this fluid non-distributable. Water must, therefore, have a great- er capacity for heat than ice. 6. What has just been said, respecting the manner in which water solidifies and ice melts, is equally true with re- gard to every liquid, which can become solid, and every solid capable of liquefaction. It may, therefore, be laid down as universally true, that, whenever liquids solidify, quiescent heat is converted into distributable heat; and yvhenever so- lids liquefy, it is in consequence of an accession of heat, yvhich becomes non-distributable in them. 7. Chemists have not only been able to deduce this gene- Thequanti- ral law respecting all liquids and solids, but have actuallyty,?f.lie,ft ascertained by experiment the quantity of heat, yvhich chan- ges Us state ges its state during the freezing of water or the liquefaction »*»thefreez- f ingof water U t • • r andmelt- 8. For example, if equal quantities of pounded ice at 32° in? of ice, and water at 172° be mixed together, the ice instantly J1?* a,scer" melts, and the temperature of the mixture is found to be only 32°. The difference between the temperature of the ice and of the yvater before mixture is 140°. Now the yvhole of this heat is put in motion, and converts the ice into water, in yvhich it exists in a non-distributable state, as it has not raised its temperature. From this experiment, it is concluded, that, when ice liquefies, 140 degrees of heat are reduced to a non-distributable state; that is, to a state in which they no longer affect the thermometer. 9. When the foregoing experiment is repeated with tyvo portions of yvater of equal weights, one portion at 32° and the other at 172°, the result is widely different. The tem- perature of the mixture is found to be an exact mean of the temperatures of the tyvo portions of water before mixture; for here the heat, which enters the yvater at 32°, does not become non-distributable, but gradually raises its tempera- ture, and assumes a state of rest only, when half the excess of the heat contained in the hotter portion has entered the colder. 3L 450 1MPONDERAMLE BODIES Book ii. 10. The fact has already been mentioned, that, when wa- Expiana- ter cooled down below the freezing point is made to freeze, tion of the just so much heat is thrown into a distributable state, as is watercwl- safficient to raise the temperature of the ice formed and of cddown the remaining yvater to the freezing point. If the question be below the asked, yvhv the quantity of heat thrown out is exactly suffi- ti-eezing -. . * J , . . , J point, when cient to raise the yvhole to the freezing point, the true an- it freezes, swer perhaps is, that it could not be less, because the fustM?" whole of the water in a freezing condition would not be fro- muciiheat zen, and it could not be more, compatibly with any conge- duce the* lation at a11* Hence it is,- as Dr. Thomson has proved by freezing experiment, that the quantity of ice formed by agitation in turePtra* water» cooled down below the freezing point, bears a con- stant ratio to the previous coldness of the liquid; since the colder the yvater, a greater quantity of ice may be formed, without the evolved caloric being sufficient to raise the tem- perature of the yvhole above the freezing point. Dr. Thom- son has found, that, when water is made to freeze after being cooled 5° below the freezing point, the quantity of ice formed amounts to ^Vtn Part of the whole; yvhen cool- ed down 10° below the same point, the ice amounts to ,'jth part, or twice as much. Hence this chemist has inferred, that, for every 5° of diminution of temperature below the freezing point, ^th part of water freezes suddenly by agi- tation; and consequently, that if a portion of water could be cooled down below the freezing point 28 times 5°, or 140°, upon agitation, the yvhole of it would be suddenly converted into ice of the temperature of 32°; in other words, its tem- perature would be suddenly raised 140°. Thus the reader perceives, that the same quantity of heat becomes distributa- ble or capable of affecting the thermometer by the freezing of yvater, as is rendered non-distributable by the melting of ice. MM'.nerin 11* It may be curious to inquire, in what peculiar man- wiiK-h wa- ner heat leaves water with the effect of making it solidify. ter trcezes T , , , , .- . ° , explained. It cannot be, that, when water is at the freezing point, the cooling cause acts exclusively upon a small portion of it, * and converts it into ice by abstracting 140° of caloric: by no means; for the 140° of caloric, yvhich appear when water is converted into ice, is the consequence and not the cause of its freezing. It appears to me, that the phenomena, vrhich take place in the freezing of water cooled down below the freezing point, furnish the basis for a true explanation; since it is reasonable to suppose, that, during the ordinary freezing of water, the same happens on a small scale, which occurs in these other cases on a large one. When water is cooled down to the freezing point, it must suffer CALORIC. 451 a small decrease of temperature before it can freeze. Now Ckap. il I suppose, that, when the first portion of ice is formed, it*~ is exactly so much, as is sufficient, by means of the heat it gives out in the freezing act, to raise the yvhole (both wattr and ice) to the freezing point. If the cooling cause continue to act, the temperature of the remaining water, sinks again, and again so much ice is formed, as is suffici- ent, by its heat evolved, to raise the yvhole once more to the freezing point. In this manner, by the water repeat- edly falling below the freezing point, and being as often raised to the same point, by heat evolved during the freez- ing of a portion of it, the whole at last becomes converted into ice. This explanation yvould seem to be much more consistent with facts than the one, which insists upon the evolution of distributable heat, during freezing, sensible to the thermometer, while standing at the freezing point.* 12. By a similar mode of reasoning, the manner in yvhich Manner in ice melts may be explained. The ice, at the freezing point, wh,ch ,ee receives a small increment of temperature; and, at the same plained! moment, so much of it melts, as is sufficient, by the heat yvhich is necessarily absorbed, to reduce the yvhole again to the freezing point. The ice receives another small incre- ment of heat, and, by the melting of another small portion of it, is again reduced to the freezing point. By a repetition of these small risings and fallings in temperature, the whole at last becomes dissolved. 13. All that has been said of the conversion of solids into liquids and the contrary, by the addition or abstraction of heat, is equally applicable to the conversion of liquids into vapours, and the condensation of the latter into the former. Distributa- 14. With respect to yvater, chemists have been enabled ,,'e lieR** to ascertain by experiment, hoyv much heat, previously in hitoquies- a distributable state, is rendered quiescent and not sensible cent heat to the thermometer by its conversion into steam. One of <£""&■£ -n the most intelligible experiments, by which this quantity is of water'in- estimated, is the following: By means of pressure, in a ma-t08team- chine called a Papin's digester, water may be heated to the temperature of 4009, that is 188° above the boifing point. This becomes practicable, in consequence of the pressure preventing the formation of steam, by which alone, in ordi- nary cases, water is prevented from becoming hotter than the boiling temperature. If the mouth of the digester, con- taining the yvater thus heated, be suddenly opened, about £th of it immediately escapes in the form of steam, yvhich ne- * It is asserted that a delicate thermometer, suspended over water while in the set of .freezing, is capable of indieat'mq; this evolution of heat by the rise «f the mereurv. 452 IMPONDERABLE BODIES. The quan- tity thus rendered non-distri- butable amounts to B« k ii. cessarily has the temperature of 212Q, and the remainder immediately falls in temperature to the boiling point. Now the ^th of the yvater, converted into steam, at the moment of its conversion, contained 188° of heat, which, after its con- version, are no longer sensible to the thermometer, as it in- dicates the temperature ot 212* only; but, besides these 188" of heat, the steam formed has rendered non-distributable 188°, received from each of the remaining fifths of the wa- ter, or four times 188°, equal to 752°; which, added to the 188°, yvhich the steam, before its conversion, had contain- ed in a distributable state, will give 940° of heat, thrown into a non-distributable state by the conversion of water into steam. 15. By other experiments, the quantity of heat, yvhich be- comes non-distributable during the conversion of water into steam, is indicated to be above 1000°. The calculation by Lavoisier makes it about 1000°. Upon the whole, yvhile nearly 1000 results remain thus discordant, the quantity may be taken degrees. at 1000° yvithout any sensible error. Dr Black 16. The reader has noyv been put in possession of the fiJst eV leading facts, ascertained respecting the changes of state, piciintMi inc 1*1.* *i i • • "i manner in yvhich caloric undergoes during its agency in the conver- which heat sion of solids into liquids, and liquids into elastic fluids. non^dlstri- ^t *s proper now to inform him, that, for their discovery, butabieinii-and for the proper conclusions to be drawn from them, qj'f^rm^ chemistry is indebted exclusively to the sagacity of Dr. lids, and in Black. This chemist designated the heat, which becomes vapours non-distributable during the change of state of a body, la- tent heat, on account of its lying hid as it were, and thereby not influencing the thermometer. He supposed that it be- came chemically combined with a body after its change. 17. It has already been mentioned as probable, that li- quids have a greater capacity for heat than the solids, from yvhich they are formed by the agency of caloric. The same reasons, yvhich m;-ke this probable, concur to create a belief, that vapours have a greater capacity than the liquids from Absolute yvhich they are obtained by the same agency. This appears caloric of to have been the opinion of Dr. Irvine of Glasgow, who cuiated by a*so supposed, that the capacity of bodies for heat remained Dr. Irvine, the same at all temperatures. These two opinions taken for granted, he proposed to found upon them a calculation to determine the absolute quantity of heat in bodies, as mea- sured bv degrees of the thermometer. To apply his method of reasoning to the case of water, he supposes, that the num- bers which express the capacities for heat of water and ice, express also the ratio of their absolute calorics; and as the capacity of the former to that of the latter is as 10 to 9, formed from Ii quids. CALORIC 453 therefore, the quantity of heat in water at 32° is to that in Chap, ii. ice at the same temperature, as these numbers are to each "~ other; or, which amounts to the same thing, water, in the act of freezing, gives out ^th of its heat; but this tenth of the heat of water is ascertained to be equal to 140°, there- fore, the whole of its heat must be equal to 140 x 10, or 1400°. 18. The plan, upon which Dr. Irvine's calculation is con- Dr Irvine's ducted, is unquestionably correct in itself; but the data upon daU» ™% which it is founded are far from being certain. Some experi- ments, indeed, seem rather unfavourable to the idea, that the capacity of a body for heat remains the same at all tem- peratures. Dr. Irvine supposed also, that, when a body changed its state, its capacity was altered, and heat conse- quently either given out or absorbed. Thus, when yvater is converted into steam, heat is absorbed, or rendered non-dis- tributable, because steam has a greater capacity for heat than water. But the absorption of the heat cannot be accounted for, by saying, that steam has a greater capacity for heat than yvater; for the question arises, what converts the water into steam? It cannot be answered, heat; since this would amount to saying, that water becomes steam because it ab- sorbs heat; and water absorbs heat because it becomes steam. All that can be safely said is, that, at a particular temperature, water so combines with a certain quantity of heat, as to render it non-distributable; and that this peculiar combination of water and heat results in the formation of an elastic fluid, of greater capacity than yvater, namely steam. III. OF CHEMICAL CHANGES PRODUCED BV CALORIC. 1. Very few words will be said under this head. It is Heat pro. mentioned for the sake of precision in the classification of duces man* the subject. The reader is already acquainted with the fact, changes that heat constitutes the most powerful means of analysis in the hands of the chemist; since it has been evinced at every step in the progress of the present yvork. Heat is supposed to produce decompositions, by altering the relative intensi- ties of affinities. It assists combination, by diminishing the force of cohesion in the particles of homogeneous bodies. 454 IMPONDERABLE BODIES BookIL SECTION VI. OF THE DIFFERENT INSTRUMENTS IN COMMON USE FOR MEASURING THE INTENSITY OF HEAT. Instru- The instruments, which it is proposed to describe in this measuring secti°n» are the common thermometer, Leslie's differential heat are thermometer, and Wedgewood'*s pyrometer. 1. Common I. OF THE COMMON THERMOMETER. thermome* ter. 1. The thermometer is an instrument, composed of a tube of glass, blown at one end into a bulb, partly filled with mercury and hermetically sealed. When it is plunged into a hot body, the mercury expands and rises in the tube; when put in contact with a cold body, it contracts and falls. In order to measure the expansion, the tube is divided into equal parts called degrees. 2. The thermometer yvas invented about the beginning of the seventeenth century. The invention is attributed by some to Sanctorius. Science, hoyvever, is indebted to New- ton for the method of making thermometers, which might be compared with each other. Thermo- 3. Thermometers, to answer the purpose of comparison, meters must have certain fixed invariable points in their scales. fixed points The temperature, at yvhich ice melts, and water boils under on their a given pressure of the atmosphere, is invariably the same; scales. these temperatures, therefore, are taken as the fixed points, and the scale is graduated in different directions from them. When a thermometer is ready for graduation, it is plunged into melting snow or ice, and the point at which the mercury- stands in the tube is marked on the glass. It is afterwards plunged into boiling yvater, and the neyv point at which the mercury rests is also noted. The space between the freez- ing and boiling points, thus obtained, is then divided into a convenient number of equal parts called degrees. 4. Different nations have followed different plans in the graduation of thermometers, but, in all of them, the freezing and boiling temperatures of yvater are the fixed points in the scale. There are four mercurial thermometers in common use in various parts of the world, differing in no other re- spect than in the manner of their graduation. Thermo- 5. In Fahrenheit's thermometer, the space betyveen the JK-diren-f ^reezing and boiling points is divided into 180°; but the be- hdi; ginning of the scale is fixed at 32° beloyv the freezing point, at the temperature produced by mixing together snow and common salt. Hence the freezing point is marked 32°, CALORIC. 455 and the boiling point 212°. This thermometer is used in Chap, il Britain and the United States. 6. In Celsius's thermometer, the space between the freez- of Celsius; ing and boiling points is divided into 100°, the freezing point being placed at zero, and the boiling point at 100°. This thermometer is used in Sweden, and has been employed in France since the revolution, under the name of the centi- grade thermometer. 7. In Reaumur's thermometer, the scale begins at the0fReau- frcezing point, and the boiling point is marked 80°. This mur: and thermometer was used in France before the revolution. 8. In De Lisle's thermometer, the space between the of De Lisle. boiling and freezing points is divided into 150°; but it dif- fers in this particular from all other thermometers, that its graduation begins at the boiling point, which is marked O, and increases towards the freezing point, which stands at 150°. This thermometer is used in Russia. II. OF LESLIE'S DIFFERENTIAL THERMOMETER. 1. This thermometer consists of a glass tube, bent in the 2. Leslie's form of the letter U, and terminating at each extremity in a thermome^ hollow bulb of the same size. The tube is partly filled with how con- sulphuric acid, tinged red by carmine. Both bulbs are al- structed. lowed to be full of air, and communicate with the tube. To one leg of the instrument, an ivory scale is affixed, divided into 100 equal parts, the zero of which is made to corres- pond to a point of the tube, a little above the bend. The other leg is left bare, and the ball, belonging to it, is called, by way of distinction, the focal ball. Before the glass is sealed, the sulphuric acid is so disposed, as that its upper surface may stand opposite to zero of the ivory scale. Now it is evident, that, if this instrument be placed in any situa- tion, in which both the balls are exposed to the same tempera- ture, the sulphuric acid will not move in the tube, since it is pressed equally in contrary directions by the air contained in the balls. But supposing, that the focal ball be exposed to a temperature higher than that yvhich influences the other ball, then, by a necessary consequence, the sulphuric acid is pressed towards the colder ball, and rises in the leg to which the scale is attached, proportionably to the excess of tempera- ture of the focal ball over that of the other ball; and this rise is measured by the divisions marked on the ivory scale. This Uses of this instrument, it must be obvious, is well suited for ascertain- thermome- ing an accumulation of heat at a particular point, yvhich does ter' not extend to the surrounding atmosphere, as happens in the focus of a reflecting mirror; and it yvas by means of it, that 456 IMPONDERABLE BODIES BookII. Leslie was enabled to make such precise observations upon- the radiating and reflecting powers of different bodies. III. OF WEDGEWOOD'S PYROMETER. 3. Wedge- 1. The fitness of this instrument, for the purposes of a rometei"3 measurer OI" neat, depends upon the property which clay has of contracting in high temperatures. This fact respecting clay has already been noticed, while enumerating the excep- tions to the general law of the expansion of bodies by heat. Wedgewood's pyrometer consists of a number of pieces of structed." c^ay °*? a determinate size, and an instrument for measuring their bulk with accuracy. The latter is formed of tyvo brass rules twenty-four inches long, fastened upon a plate, half an inch apart at one end, and three-tenths of an inch at the other. The rules are divided into 240 equal parts, or tenths of an inch, called degrees. The clay pieces are small cylin- ders, first exposed to a red heat, and then made to fit be- tween the brass rules, opposite the first degree of the scale, which therefore corresponds with a red heat, or 947° of Fahrenheit's thermometer. How used, 2. The manner, in yvhich a high temperature is ascertained by this instrument, is to expose one of the clay pieces to the heat, yvhich it is intended to measure, until it has acquired the same temperature. It is then withdrawn from the fire, and when cool, slid between the brass rules; and the degree, which its bulk has diminished, is ascertained by the distance it is capable of passing up between the rules. Wherever it stops, the intensity of the heat is indicated by the corres- ponding divisions on the brass rules. Not an ex- 3. It is to be regretted that the contraction, produced by act measur- tjje same degree of heat, in different pieces of clay is not precisely the same. This instrument, therefore, cannot be considered as an accurate measurer of heat. Notwithstand- ing, its invention has been attended with considerable prac- tical utility, in ascertaining high temperatures, in operations in which great accuracy is not essential. [ 457 ] BOOK III. OF THE GENERAL PROPERTIES OF MATTER, UPON WHICH CHEMICAL CHANGES DEPEND. 1. In the tyvo books, just completed, of the science of Book III. chemistry properly so called, all the bodies, yvhich come ^7~ J7T" under the notice of the chemist, have been described, and sent book a history of the chemical chances produced by their mutual treatsoi the action has been given. Those two books, therelore, may be chemical consider^ d as having been employed in recording the ef- changes. fects of chemical action: the causes of th se effcos, or the general principles upon yvhich chemical changes occur, will form the subject of the present book. 2. What takes place during any chemical change must be considered as a mere insulate I fact; and reasoning upon such fact, the mind does not hesitate to believe, that, upon whatever proptrties impressed upon matter, the changes oc- curring in one chemical action depend, upon the very same properties all chemical changes must depend. 3. Chemical changes always take place at insensible dis- These tances; the causes of these chancres, therefore, must operate t'1',nses ..... , ° ' ■ take place at insensible distances also. atinsensi-, 4. Whatever the power may be, yvhich holds together the b,e distan- particles of bodies which form masses, it is a force yvhich penVu" on" operates at insensible distances. It is a force also, yvhich va- attractions ries in intensity, as is proved by the different degrees of tue^n'simi- counteracting force necessary to overcome it. This force lar particles has been called the attraction of aggregation. ot matter; 5. Again: Whatever it may be which holds together dis- dissimilar similar particles in a chemical compound, it is a force yvhich P;"'l^lLJS- acts at insensible distances also. That this force is different attraction is in intensity, when acting between different dissimilar parti- thatot ag- cles, cannot be proved by any mechanical means, but this fh^uer fact is demonstrated by yvhat occurs in chemical decompo- chemical sition; for here a force, yvhich holds together dissimilar par-attracUon' tides, is overcome by a force the same in kind; the overcom- ing force must, therefore, be greater in degree. This force, on account of its holding together dissimilar particles, is called chemical attraction, or, more usually, chemical affinity. 6. Thus it is perceived, that th>*re may be fairly deduced, from the phenomena exhibited by matter, the existence of an attraction between its particles, acting at insensible dis- tances, and varying in its intensity under different circuim 3 M 458 ATTRACTION AT INSENSIBLE DISTANCES. Book III. stances; and this attraction, so acting, may either be between particles the same in kind, or dissimilar particles. 7. The existence of an attraction, varying in intensity be- tween dissimilar particles, is evinced in every chemical combination and decomposition. But the existence of such an attraction merely, without supposing it in some cases greater in intensity than the attraction of aggregation, would not be sufficient to explain chemical action; for supposing the attraction of aggregation to be always the stronger, there would be no force adequate to separate simil ir parti- cles from each other. Hence, therefore, it may be said, that all chemical changes may be referred to the operation of an attraction, various in its intensity, which takes place at in- sensible distances betwetn dissimilar particles of matter, and yvhich, to be efficacious, must be stronger than the same kind of attraction, occurring between similar particles. 8. Having thus given an account of the general principles, upon which chemical changes occur, it will next be proper to consider the attractions concerned in them, namely the attraction of aggregation, and chemical affinity. This will be done in the two following chapters. CHAPTER I. OF THE ATTRACTION OF AGGREGATION. (Syn. Attraction of Cohesion—Corpuscular Attraction—Homogeneous Affinity.) Attraction 1« But a few words will be said under this head. There of aggrega- IS no difficulty in understanding, that, by means of this at- inbtenrity.tn^ti011* matter is enabled to assume the form of masses. In solids, it has the greatest force; and in different indivi- dual solids, its intensity is very various. As a general rule, it is much the strongest in the metals, the tenacity of which depends upon the energy of this attraction. What is called strength in inanimate objects depends upon the degree of this attraction; and it is principally owing to the great tena- city or strength of the metals, that they are of such im- mense importance to mankind. 2. The attraction of aggregation between the particles of liquids, although much less than that between the particles of solids, nevertheless exists to a certain degree. With re- spect to water, it is proved in the formation of adrop of this liquid, in which every particle is urged towards the other by a between * certain degree of force, as is evinced by its spherical figure. the parti- 3. Between the particles of gases, there is no attraction jL.8, of aggregation. These fluids, as far as observation has yet ATTRACTION OF AGGREGATION. 459 extended, are capable of indefinite expansion; so that the Chap. I. smallest portion of them may fill the largest imaginable space. 4. The attraction of aggregation, as has been already It opposes mentioned, is always opposed to the efficacy of chemical af- 0fechemieai finity. Whenever the particles of two dissimilar solids or affinity. liquids combine by chemical affinity, it is because this latter attraction is stronger than the attraction of aggregation be- tueen the individual particles of each body. This fact sup- plies the reason, why heat is so efficacious in facilitating chemical combination; for it lessens that power, which ne- cessarily opposes chemical affinity. When a solid is convert- ed into a liquid by heat, in so far it is rendered more capa- ble of chemical combination. When a liquid is by the same means converted into an aeriform fluid, the attraction of ag- gregation, as an opposing force to chemical affinity, becomes entirely removed. CHAPTER II. OF CHEMICAL AFFINITY. (Sometimes called, Heterogeneous Affinity.) 1. Chemical affinity has already been explained to be that Chemical attraction, by which particles not of the same kind are held a^nlty.ex together. A particle of sulphate of soda is composed of a particle of sulphuric acid and a particle of soda, held to- gether by chemical affinity; but the different particles of the salt itself are kept together by the attraction of aggregation. 2. The force of this peculiar attraction varies very much according to the bodies between which it is exerted; and it is upon this variableness in its force, that all the decomposi- tions, which can be effected by the chemist, depend. 3. Chemists at an early period attempted to ascertain the laws of chemical affinity, by observing the phenomena of composition and decomposition. 4. The first step in this investigation yvas made in 1677 its nature by Mayow, who demonstrated, that the previous notion, that investiSat- the ingredients of any chemical compound are destroyed iny0wm *" their union, yvas not founded in truth. This chemist re-l677: marked, with some precision, the power, which certain sub- stances have, of displacing others from their combinations. These observations were much further extended in 1718 by and by Geoffroy, senior, yvho ascertained a much larger number GfG . r07* decompositions, and attempted to prove, that bodies separate msT'" 460 ATTRACTION AT INSENSIBLE DISTANCES. Book III. eacn other from chemjc.,] combinations in an invariable or- der, «hich depended upon the comparative force of their attractions. This chemist was the first to construct tables of affinity. Bergman 5. Nothing of importance was done, in investigating the on th?sub-*aws ot chl mical affi"itv, from this period, until Bergman jet-tin i"/"5; published his dissertation on elective attractions in 1775. e"thatSche- Accorcl'ng to this philosopher, chemical affinity is a certain mical affini-invariable force; so that when a substance is presented to a *?.'!-8kinln' comP°und, h ving a stronger affinity for one of its constitu- force. ents tnan tncv have for each other, it necessarily combines with such constituent and separates the other. Berg nan il- lustrated his opinions, and answered the objections of others with so much success, as to cause his doc rine to be univer- sally admitted, and to be considered as some of the best de- monstrated parts of the philosophy of chemistry. He con- structed very copious tables of chemical affinity, in which the different chemical bodies were arranged in columns, in the order in which they separated each other, considered with reference to a given substance which was placed above them. The body, which separated all the rest, was placed at the head of the column, and the remainder in the order in which they separated each other. The opi- 6. The opinions of Bergman on chemical affinity continued nions of to receive the universal assent of chemists, until Berthollet comlatted published a dissertation on affinity in the third volume of by Berthol- the Memoirs of the Institute, and his Essay upon Chemical let in 1803. statics, in 1803. According to this chemist, affinity is not an invariable force. It is, indeed, different in degree in dif- ferent bodies; and the affinity of one body for any other is modified by the mass, in which it is presented for combina- tion. A body, which has an affinity, for one ingredient of a compound, stronger than that by which such ingredient is held, does not necessarily separate the whole of such ingre- dient, but combines with a portion of it only; and the por- tion separated bears the same relation to that yvhich remains still combined, as the respective affinities of the attracting body and the retaining body have to each other. Again; a body, reputed, by the old doctrine, to have a weaker affinity for one of the constituents of a compound than such consti- tuents have for each other, may nevertheless, according to Berthollet, cause a partial decomposition, by bringing into operation the modifications occasioned by mass. For exam- ple, a large quantity of potash is capable of separating a portion of sulphuric acid from a small quantity of sulphate of barytes. 7. The doctrines of Berthollet, respecting affinity, are in CHEMICAL AFFINITY. 461 many respects very differ nt from those advocated by Berg- Chap il man. According to the last named chemist, when one affi- n- cirines nity is creater than another, the weaker affinity has no in-<•» B-rgman n • 111 •»• •! and Ber- fluence in a result, and decomposition is necessarily com- th,)llet con. plete: according to Berthollet, when a body has an attrac-trasted. tion, tor another body in combination, stronger than that by which such body is held, the body attracted does not become wholly separated, but is divided, between the attracting bodv and the body with which it was first united, in por- tions, bearing the same relation to each other, as the respec- tive affinities of these bodies. According to Bergman, mass has no influence over decomposition: according to Berthol- let, the poyver of attraction of the decomposing body is in- creased by the relative excess of its mass. b. Although mass appears to be efficacious, it by no means identifies chemical affinity with gravitation; for it is not absolute but relative mass, which has an influence in mo- difying the force of chemical affinity. 9. The doctrines of chemical affinity, in their present un- Doctrines settled state, seem to require for their explanation, that che- Pjj^. ^* mical combinations should be divided into those which t kemiCH| affinj. place in definite proportions, and those which do not occur ty» very un- in this yvay. 10. The reader has already been made acquainted with the leading features of the atomic theory in a preceding part of this work. All combinations, which tally with this the- ory, would appear to take place according to tht principles of Bergman, mass being in nowise efficacious. This appears to be particularly the case in the mutual decomposition of salts, yv h«. re there is a complete interchange of ingredients. But when bodies do not combine in definite proportions, then mass appears to be efficacious, by increasing the quan- tity, which one ingredient of a mixture may take up of some other ingredient without being saturated. For it yyould ap- pear, that bodies have less attraction for others, with which they can comhine in any proportion within certain limits, the nearer the quantities, with which they have already com- bined, approach such limits. For example, the increase of the mass of a solvent, while the body dissolved re- mains the same, unquestionably makes the limit of combi- nation recede, and may thereby increase the affinity. 11. Since the new facts respecting chemical affinity have Tables of been made known, tables of affinity have become of compa-jj*™^' ^ ratively little value. Tables, exhibiting the order in which not^ve bodies decompose each other, must be taken with certain pr.cise in- exceptions. Thus, yvith respect to hydrogen and carbon, it is ot impossible to ascertain yvhich has the greatest affinity for 462 ATTRACTION AT INSENSIBLE DISTANCES Book hi. oxygen; for, while charcpal decomposes water at a red heat, hydrogen in its turn is capable of decomposing carbonic acid at the same temperature. Several similar anomalies in decomposition obtain with regard to other bodies. 12. It is on these accounts, that the student cannot with any safety depend upon the information given by tables of chemical affinity. There is one general rule, however, which he may recollect with advantage. It is, that acids, either uncombined or as constituents of salts, almost invariably precipitate, from acid solutions, those bases, yvith yvhich they form insoluble saline compounds. And this is equally true with regard to those bases, which form insoluble salts with particular acids. Hence the importance becomes evident ol recollecting those salts which are insoluble. [ *w 1 PART II. CHEMICAL EXAMINATION OF NATURE. IT is proposed, in the second part of the present work, to Pakt ii. make but a partial chemical examination of the differentTT---- i • r a n .ill- Subjects, objects ot na;ure. All material bodies are not equally embraced interesting to the student of medicine. The mineral kine-,n th.e 8e" , ?• . , . . ° cond partof dom constitutes a very interesting study; but it is not a ne-the present cessary part of medical chemistry. The vegetable kingdom w°rk, are furnishes a great number of important aliments and medi- thfdhemh- cines: vegetables, therefore, will be examined so far, as to try of the bring under consideration the nutritive or medicinal forms Jj"man bo" of the matter which compose them. With regard to ani- mals, the view will be extended no farther than to give the chemistry of the different parts, which compose the human body. But in taking this partial chemical vieyv of nature, the at- and theat- mosphere which surrounds the globe, and water, yvhich, in mosPhere d./r r • r • c . and waters liferent states ot purity, forms so important a part ot it, of the must not be neglected to be noticed. These portions of nature globe. are particularly interesting to the student of medicine, and should be carefully studied by him. Accordingly, the second part of this yvork will commence with an account of the at- mosphere and yvater, forming the subject of a first book. Vegetable chemistry will then be considered in a second book, and human animal chemistry, in a third book. I 464 ] BOOK I. OF THE ATMOSPHERE AND WATER, GENERALLY. Vart II. 1. A very large proportion of the matter, which consti- Book 1 tutes our globe, consists of the atmosphere, yvhich floats round it on all sidts, and the water, yvhich covers so large a Nature of portion of its surface. The height of the atmosphere cannot the atmos- De calculated; for the indefinite expansibility of air does not leave room for belief, that this fluid yvould ever refuse to- expand in open space, however rare it might become. The weight ot the atmosphere may be ascertained bv observing the weight of a column of mercury, sustained b\ its pressure in a barometrical tube. The yveight of a column of mercury, thus sustained, has been demonstrated to be equal to that of all the atmosphere, yvhich presses upon a base equal to the base of such column. The height of the column sustained by the atmosphere is different at different times, and hence it is proved, that the weight of the atmosphere varies; but taking the mean height of the barometer to be thirty inches, and consequently the mean weight of the air to be indicated by the weight of such a column, then it is evident, that the weight of a hollow shell of mercury, enclosing the earth and thirty inches in thickness, would be the same as the yveight of the whole atmosphere at a medium pressure. In this way, the atmosphere has been calculated to weigh more than 955 millions of millions of tons. The water 2". There is no method for ascertiining the quantity of of the g'°be water, of which the globe is formed, as there is no means of calculated determining the depth of the ocean, yvhich forms the great with any reServoir of this liquid. Upon the supposition, that the mean preefston. depth of the sea is not more than a quarter of a mile, and that three-quarters of the earth's surface is covered by it, Dr. Thomson calculates, that the solid contents of the ocean would be somewhat more than thirty-two millions of cubic miles. 3. What has been already said, respecting the atmosphere and yvater of the globe, may be considered as belonging to the department of mechanical philosophy rather than to che- mistry. It now becomes proper to take up the consideration of these objects for investigation separately, in a chemical point of view; and this is done in the two following chapters. THE ATMOSPHERE. 465 Chap. I. CHAPTER I. OF THE ATMOSPHERE. 1. It has already been stated in a foregoing part of this The atmo?- Work, that the great bulk of the atmosphere consists of an PJJ* ^ <* air composed of oxygen and azote. This air has been called by chemists atmospheric air. But, besides this compound air, the atmosphere contains a variable quantity of water in a state of vapour, and a small proportion of carbonic acid. So that, excluding accidental bodies which may float in it, the atmosphere is made up of L Atmos- 1. Atmospheric air, pheric air. 2. Vapour, ^.Vapour. ,-, r. . . . 3. Carbonic 3. Carbonic acid. acid. 2. In the common acceptation, however, of the term at- mospheric air, the yvhole atmosphere is meant. The pre- sence of vapour and carbonic acid, occurring in so small amount, docs not alter perceptibly its properties; and yvhen the mechanical properties of atmospheric air are investigated, it is sufficiently pure for the purpose of experiment, as it exists in the atmosphere. 3. Atmospheric air is an invisible elastic fluid. By^ rea- Properties son of its elasticity, it is densest near the surface of the ^^^j. earth, and its density diminishes with its height. It has been ascertained by experiment, that the density decreases in a geometrical, as the height increases in an arithmetical pro- gression. Its apparent visibility, deduced from the blue co- lour of the sky, has been ascertained to depend upon the presence of vapour. Saussure has found in his observations, that the sky has a deeper shade of blue, the higher the point is, from yvhich it may be vieyved. This circumstance, he ascribes to the diminishing quantity of vapours suspended in the higher regions of the air, affording a diminished reflection of light. 4. By the common consent of chemists, atmospheric airTheweighr is assumed as the standard, with which the specific gravities ofa''sase- r n i- n • i i ii- •<- oim fluids, ot all aeritorm nuids are compared; and hence its specific compared gravity is taken at unity. Compared bulk for bulk with yva- with !t as a ter, it is 828 times lighter than this liquid. One hundred cubic inches of it weigh 30.5 grains, troy. 5. According to the most accurate analyses, reduced toTtscompo- numbers which best accord yvith the atomic theory, atmos-s'lion .gl,I?n" pheric air is composed of Oxygen 8*00—one atom. Azote 26*33— From this statement it appears, that the proportion, in which oxygen and azote combine in the formation of atmos- 3N 466 THE ATMOSPHERE AND WATER GENERALLY. Part II. pheric air, does not acord yvith any atomic supposition ot Book 1. cotnbination. lhe quantity of azote, combined with one atom of ox> gen, indicates someyvhat less th.m tyvo atoms. Atmospheric air is undoubtedly a chemical compound, al- though its ingredients may be united in a manner peculiar to the gases, y\hen they combine without losing their gaseous form. by bulk, One hundred parts of atmospheric air are composed, by bulk of Oxygen 21 Azote 79 and by weight. First step in the dis- covery of the consti- tuents of al> mospheric air, made by Priest- ley. by yveight of Oxygen Azote 100 23*299 76*701 Scheele's researches upon at- mospheric air; and his con elusions. 100*000 6. Having given the composition of atmospheric air, it is nex proper to lay before the reader some account of the discovery of its compound nature. The first step in this ob- ject of research was made by Priestley, in his discovery of oxygen gas. This chemist supposed, that the gas now known by the name of azote was in fact nothing but ox-, gen gas saturated with phlogiston; and hence he believed, that com- mon air was oxygen gas, combined with a variable quantity of this imaginary principle. Ahout the same time that Priestley came to this conclusion respecting the nature of atmospheric air, Scheele was employed in making experi- ments with a view to determine its composition. This che- mist found, that, upon exposing a given portion of air to the action of the liquid sulphurets, its bulk was diminished, and it was no longer capable of supporting flame. He, therefore, concluded, that the portion which gave the air the property of supporting fl une had disappeared, and called what re- mained foul air. He ascertained also, that the air which had disappeared yvas the same with that, yvhich is extricated from nitrate of potash (nitre), or peroxide of manganese by heat; since upon mixing this air yvith his foul air in certain pro- portions, he produced atmospheric air. To this latter air, he gave the name of empyreal air. ■ 7. Thus it appears, that Scheele discovered the actual constituents of atmospheric air. He, however, did not be- lieve, that the effect of the liquid sulphurets was to absorb his empyreal air. According to his theory, this latter air disappeared in consequence of its combining with the phlo- giston of the sulphuret; in which state of combination, he THE ATMOSPHERE. 467 supposed it to form caloric, and to pass through the vessel. Ohap.l So that Scheele, like Priestley, erred in the theory, which he adopted respecting the constituents of air. 8* Lavoisier appears to have been the first chemist, who Laroisier drew the proper conclusions from the experiments, which fhrf^r0e*r indicated the constituents ol atmospheric air. He exposed conclusions mercury to its boiling heat, and found that it became con-fr°™^he verted into the peroxide (red oxide). Part of the air which "Jnttl" had been confined over it had disappeared, and what remain- which indi* ed was incapable of supporting flame. This chemist ascer- c0nestitu_e tained further, that the air which had disappeared had actu- entsof at- ally combined wiih the peroxide formed; for when this ox- ^pnenc ide yvas exposed to heat, it yielded an air, which, by mix- ture with the residual air just spoken of, reproduced the at- mospheric air. Lavoisier also ascertained, that the liquid sulphurets actually absorbed one constituent of atmospheric air, the constituent afterwards known by the name of oxygen gas, and that the sulphur which they contained was acidi- fied. Thus he disproved the theory of Scheele yvith respect to the disappearance of the oxygen gas. 9. As soon as the composition of atmospheric air was sa- The purity tisfactorily made out, upon comparing together the proper- pher™°a8fr ties of its constituents, chemists very confidently concluded, presum- that its purity must depend upon the quantity of oxygen ed at firs' which it might contain. Accordingly, they set about con- Up0n the triving a number of instruments, bv which the proportion of quantity of ... . • . c * \ . oxygen it oxygen, existing in any given portion ot atmospheric air, mignt con. might be measured. These instruments, from their supposed tain. use in ascertaining the purity of air, were called eudiome- ters. 10. All the eudiometers invented agreed in being so many Principal different pians, by which the oxygen contained in any given terg10^" portion of air might be wholly abstracted; and the purity of those of the air experimented upon was supposed to be proportional PrlestJey> to the smallness of the residuum. The principal ones are \0ita and those of Priestley, of Scheele, of Volta, and of Berthollet. Berthollet. The eudiometer of Priestley depended, for the results yvhich it gave, upon the property possessed by deutoxide of azote (nitrous gas), of absorbing oxygen gas from atmospheric air and being converted into nitrous acid. That of Scheele con- sisted of a portion of air, confined with an alkaline sulphu- ret, or a moistened mixture of iron filings and sulphur, in an inverted graduated glass tube, over yvater. These sub- stances have the property of absorbing all the oxygen con- tained in any insulated portion of atmospheric air. Hence the quantity of the oxygen is indicated by the quantity of air which has disappeared, as measured by the ascent of the 468 THE ATMOSPHERE AND WATER GENERALLY p^*t I'. water in the tube. Volta's eudiometer consisted of a mix- _______ ,ure* >n proper proportions, of atmospheric air and hydrogen gas, v\hich was fired by the electric spark. The hydrogen by its inflammation separates all the oxygen, the product being water; so that yvhat remains is pure azote. The oxy- gen is indicated by the diminution in bulk of the airs em- ployed. Berthollet's eudiometer indicated the proportional quantity of oxygen in atmospheric air by means of the slow combustion of phosphorus. This combustible was confined yvith a given portion of air over water. After the lapse of some time, the whole of the oxygen present became ab- sorbed. Atmosphe- n. Xhe result of the experiments made with eudiometers ric :tira!- , , l . . ways con- nas Deen to show, that atmospheric air, from whatever situ- tains the ation it may be obtained, always contains the same propor- poin.n'of t'ons 0,r ox>'gen and azote. Air has been examined from oxygen. different parts of the world; it has been analyzed as it exists on the tops of the highest mountains, and in situations more than tour thousand feet above the earth's surface, from which height it has been brought down by balloons; it has been subjected to experiments as it exists in places in the vicinity of marshes, and where putrid and noxious effluvia abound; and notwithstanding it has ahvays been found to contain exactly the same proportions of oxygen and azote. Thus, then, have terminated the eudiometrical experiments, from which so much was expected in elucidation of the hid- den causes of the unwholesomeness of air in particular situ- ations, and during the prevalence of epidemic diseases. They have shoyvn most clearly, that the causes, which ren- der atmospheric air noxious, are not such as produce che- mical changes upon it, but probably are of so hidden a na- ture as to be out of the reach of chemistry to discover. Besides at- 12. Having finished the consideration of atmospheric air, a^'Theat0- °^ wh'cn Vtry nearly the whole bulk of the atmosphere is ruu'sphere composed; it is next proper to consider its other compo- contains mnt p,rts, namely, water and carbonic acid. state of 13. it has been ascertained, that the atmosphere in its vapour. dryest state contains a quantity of water. Thus concentrated sulphuric acid abstracts moisture from it under all circum- stances; and hence this acid by exposure to air becomes gradually more and more diluted, or in other words loses its strength. Some substances imbibe water from the atmos- phere y\hen it is loaded with moisture, and part with it again when it becomes comparatively dry. Such substances have been employed to measure the quantity of moisture, which may exist in the atmosphere at different times, by taking advantage of their property of expanding by absorp- THE ATMOSPHERE. 469 tion of moisture, and contracting by its abstraction. Instru- Chap. I. ments constructed by mens of such substances are called j,nstru_ hygrometers. Saussure's hygrometer is tormed of a human ments hair, so arranged as to move an index. Deluc's hygrome- * tJ? Jh'en ter is the same in construction as Saussure's, but the hygro- quantity of metric substance en.ploved is a thin slip of whalebone. The !?ol8VJi'!Lm , • .it 1 • r » the atmos- hygrometer invented by Wilson consists ot a rai s bladder, phere, call- to which is fixed a tube, part of which, together yvith the ed h)Sl°- bladder, is filled with mercury. The contractions or di- latations of the bladder produce a corresponding rising or falling of the mercury in the tube. The scales of hygrome- ters are formed by ascertaining two points, the extremes of moisture and dryness, and dividing the intervening space into one hundred equal parts, calkd degrees. The point of extreme dryness is obtained by exposing the hy grometer to air, made as dry as possible by salts which are known to have an avidity for moisture; and the point of extreme mois- ture, by exposing the instrument to air, in its most humid state. 14. It was originally supposed, that water existed in the Water is atmosphere in a state of dissolution, and many philosophers "otdissolv- i r , ... . . „. . ' . . - / r ed in the at- nave embraced this opinion. 1 his supposition, however, ap- mosphere. pears to have been completely disproved by Dalton, who considers, that the water, existing in the atmosphere, is al- ways in the form of an elastic vapour. The following very conclusive reasons have been adduced by this chemist in proof of this opinion. [l.] Water loses its liquid form faster when exposed to a rare air than to a dense air; and it disappears fastest of all in an exhausted receiver. Now this is just what ought to take place on the supposition, that water exists in the atmos- phere in a state of vapour, but diametrically contrary to what ought to occur, if the atmosphere acted as a solvent merely. [2.] When water disappears in air by yvhat is called spon- taneous evaporation, cold is generated. Now if the water which disappears is merely dissolved, there is no reason why cold should be produced; whereas, on the supposition that it exists in the air in a state of vapour, the production of cold would be a necessary consequence of its evaporation. [3.] Mr. Dalton has proved that water, which is present in air, possesses the same degree of elasticity, as it does in a state of vapour, in a vacuum, at the same temperature. Therefore the conclusion is unavoidable, that it exists in the state of vapour in air. 15. Nothing has as yet been said respecting the quantity Quantity of of water, in a state of vapour, in the atmosphere. This is Thermos- 470 THE ATMOSPHERE AND WATER GENERALLY Part ii. known to every one to be very variable. Saussure calculates, °°K that a cubic foot of air, when fully saturated with moisture, phere,vari-contains about eight grains of water, or j^th part of its weight. Dalton, from nis experiments, concludes, that ihe medium quantitv ot vapour, h^ld by the atmosphere in England, is ^.h of its bulk. The third 16. The other ingredient in the atmosphere, carbonic acid, part'oflh"1 is a*wa.vs present, although in small amount. It has been atmosphere detected in the atmosphere of mountains, and in air, yvhich achn'tTx0 kac* been brought down from a very grea. height above the istsinaii earth's surface by means of balloons. Its quantitv, estimated places, and by bulk, according to Humboldt, varies from on.- to half a heights. Per cent. Dalton calculates its quantity at T-tW'h °f the bulk The quan- °f the atmosphere, that is, T\-th of one per cent.; but the me- tity piesent thod adopted by this chemist for ascertaining the point is stated by not susceptible of much precision. Considering how great a chemists, quantity of this acid is formed during the respiration of ani- mals and in combustion, it must be matter of surpiisi, that so small a portion of it exists in the atmosphere. It has i»ei n ascertained,that air, containing fch of its weight of carbo- nic acid, extinguishes flame and is noxious to animals. There is reason, however, to believe, that the vegetable kingdom prevents the occurrence of any over-proportion of carbonic acid in the atmosphere; as it has been completely ascertained, that plants decompose this acid during their ve- getation. CHAPTER II. OF WATER. 1. Water having been noticed incidentally only under the head of hydrogen, it becomes necessary to give it a par- ticular consideration; and this will be done in the present chapter. Properties 2. Water, rendered pure by distillation, is a transparent ^pure wa- Xiquici, destitute of colour, taste, or smell. In its purest state in nature, it contains atmospheric air, carbonic acid, and carbonate of lime. It loses its gaseous constituents by boil- ing, and becomes flat and insipid. By the common consent of chemists, it is made the standard of comparison of the specific weight of all solid and liquid bodies. A cubic foot of water, at the temperature of 4' >9, at which point its den- sity is greatest, weighs very nearly one thousand ounces, avoirdupois. 3. When cooled down to the temperature of 32°, water takes the crystallized form, and is called ice. When expo- WATER. 471 »ed to a heat of 212°, it becomes an elastic fluid tinder the Chap, ii. name of sttam. Steam, at the temperature of 212° and un- iu tVeez- der a medium pressure, is 1698 times lighter than an equal ^Kl^t, bulk of water. Its specific gravity is 0*623, compared ingpoin'tj' with atmospheric air as 1. At high temperatures, its tlasti- 2i-«. citv is exceedingly great. It is by its elasticity that steam acts, in causing the niOtion of that most useful machine^the steam engine. 4. Wattr, as it exists in nature, is distinguished by seve- Water is rai names, accordiner to its quality and the sources from distinguish- o * * , qi\ into sc- which it is obtained. Rain water constitutes a very pure Veral kinds. water; it contains, however, common air and carbonic acid gas, and some carbonate of lime. Snow water is very pure, and destitute of any air. The yvater of rivers is very variable in its purity, and as to the foreign bodies yvhich it may con- tain; and this arises from the particular nature of its bed. In general, this water contains the usual gaseous constituents, together with a small quantitv of carbonate of lime and chlo- ride of sodium (common salt). Well water is generally a very impure kind of water. It is usually obtained from a very considerable depth in the earth, where water is almost always impregnated, by gradual filtration from the surface, with a number of salts. Well water is most frequently of that kind yvhich is called hard water, so called from its cur- dling soap. Such water is unfit for washing clothes and other domestic purposes, and owes its property of decom- posing soap to the presence generally of sulphate of lime (gypsum). The acid of this salt, when it meets yvith soap, combines with the alkaline base of the latter, while the lime forms an insoluble compound with its fixed oil. 5. By far the largest portion of the water of the globe Sea water contains, dissolved in it, a number of substances in pretty ye"aj"snus0!e" large amount, constituting what is called sea water. A stances. great number of experiments have been made to ascertain the exact constituents of sea water. The amount of the substances dissolved in it has not been found to differ much in different latitudes; it varies from three to four per cent. 10,000 parts of sea water, obtained from the Frith of Forth, of the specific gravity of 1*029, was found by Dr. Murray Analysis of tO contain of of sea water Chloride of sodium (common salt) 220*01 ivLrraV. magnesium (muriate of magnesia) 42*08 calcium (muriate of lime) 7*84 Sulphate of soda (Glauber's salt) 33*16 303*09 472 THE ATMOSPHERE AND WATER GENERALLY. Part II. Book I. Effects of important chemical substances on water. It is capa- ble of being oxidized to various de- grees . This proportional quantity of constituents for sea water amounts to about 3 per cent. The chloride of sodium (com- mon salt) amounts to 2) per cent. In analyses of sea water as usually made, the sulphates of lime and of magnesia are given. These salts arc not among the constituents of sea water in the above analysis; and Dr. Murray has shown, that they do not exist in sea water, but are formed by double decompositions, which occur during the usual processes of analysis by evaporation and crystal- lization. 6. Some of the chemical relations of water have been given, in the account of almost every substance treated of in this work. Notyvithstanding, it mav be proper to reca- pitulate some of them in the present chapter. Water is not decomposed by any of the undecompounded supporters or by phosphorus or sulphur; but charcoal, at a red heat, ef- fects its decomposition, carbonic acid and bih\drogur. t of carbon being formed. It is decomposed rapidly bv potassi- um and sodium, hydrogen being extricated, which infl.imes by the heat generated, and the combustibles themselv. s con- verted into potash and soda respectively. It is decomposed also, by iron, zinc, antimony, and tin, when assisted by heat; but is not acted upon by copper, silver, gold or pla- tinum. It combines with the alkaline salifiable bases both in the solid and liquid form; but with the earthy bases, in the form of a hydrate only. It forms hydrau-s also with a number of salifiable bases of the third class, commonly call- ed metallic oxides. 7. Water is capable of combining yvith oxygen. This ex- traordinary discovery was made, towards the close of the last year, by Thenard, while pursuing his researches on the oxidizement of different substances, to yvhich he was led by his previous discovery of the oxidized acids. [l.] The first process, which Thenard pursued to oxidize water, was to pour, by degrees, barytes water upon oxy- sulphuric acid: sulphate of barytes was immediately form- ed, and the excess of oxygen of the acid became transferred to the water. By this method, water was obtained, contain- ing six times its volume of oxygen. This chemist after- wards obtained water, containing forty-one times its vo- lume, in the following manner: he placed 1200 parts of water, containing three and a half times its volume of oxygen, under the receiver of an air pump, with a cap- sule containing sulphuric acid placed above it. Upon ex- hausting the receiver, the oxidized water became congealed, and, after the lapse of some days, yvas reduced to 30 parts, yvhich proved to contain all the oxygen, yvhich existed ori- ginally in the 1200 parts. WATER. ^yg [2.] Water, containing forty-one volumes of oxygen, was Ghap. II. found to possess the following properties. It is . n insipid, inodorous, colourless liquid, not decomposable by freezing, or in the vacuum of an air pump. It disengages its oxvgen upon boiling. Its oxygen becomes disengaged also by the addition of metallic oxides, »is, dur- ing the years 1814 and 1815, by H. Davy, Gaultier de Claubry, and,John. Davy discovered traces of iodine in them; but Gaultier de Claubry has subjected several of them to an elaborate analysis, by which it appears, that io- dine exists in them in the state of hydriodic acid, combined with potash. ' 8. Kinic acid has heretofore been found in the cinchona officinalis or peruvian bark only, combined with linie. 9. Gallic acid exists in a great number of plants, chiefly in their barks. As far as observation has yet extended, it occurs most abundantly in different species of oak and in sumach. SECTION II. OF TANNIN. Tannin ex- 1. Tannin is a peculiar vegetable substance, which exists •stainnut- very abundantly in nut-galls. The soluble portion of these vegetable productions, which amounts to somewhat less than two-fifths of their weight, is found to consist of two-thirds tannin, and the remaining third, of gallic acid, mucilage, extractive and lime. Many methods have been proposed to obtain the tannin perfectly pure from the solution, but none of them appear to answer the purpose completely. It may- be obtained tolerably pure by mixing lime water with the solution, and treating the precipitate thus formed with di- luted nitric acid. Upon filtration a substance is left behind, which is tannin, contaminated however with a portion of extractive. Account of 2. Dr. Lewis, while pursuing some experiments instituted its discove- t0 ascertain the best method of making ink, observed some of the properties of tannin, yvithout being able to obtain it in a separate state. Deyeux was, perhaps, the first chemist, who made out the peculiar nature of tannin. Seguin ascer- tained, that it was the substance which combined with leather in the process of tanning. Hence it was called tan- nin or the tanning principle by the French chemists. TANNIN 479 .>. Tannin, in the purest state in which it can be obtained, Chap. I. is a brittle substance, possessing a brown colour, and break- propertjes ing with a resinous fracture. Its taste is bitter and very astringent. It dissolves readily in both hot and cold water, and forms a solution, which does not undergo spontaneous decomposition. It is insoluble in pure alcohol; but alcohol, containing T^th of its weight of yvater, is capable of effect- ing its solution. Nitric acid communicates oxygen to it, and converts it into a yellowish-brown matter, similar in pro- perties to extractive. With the metals, it does not appear to combine; but with most of their oxides, it forms insoluble compounds. This latter property makes the infusion of nut- galls very useful in precipitating metallic solutions. 4. One of the most important properties of tannin is that Forms au of forming an insoluble compound with gelatin (glue).ill80luble Hence these two substances are reciprocally the tests of each wlth^ei"' other. It combines with all the alkaline, and nearly all the tin- earthy bases, and is thereby deprived of its property of pre- cipitating gelaiin. It combines also with most of the acids, forming with them compounds more or less soluble. Nitric and sulphuric acids, however, decompose it by their action. 5. According to Berzelius, tannin is composed of Hydrogen 4*186 Carbon 51-ltiO Oxygen 44*654 100-000 6. A substance, very similar to the tannin found ready Artificial formed in certain vegetablts, may be obtained by the action tamiin ob" of diluted nitric acid on charcoal. It is called artificialJheacthfn tannin. Science is indebted for this discovery to Hatchett. of nitric It is formed by mixing together 100 grains of charcoal, £^1. and 500 grains of nitric acid of the specific gravity of 1*40, diluted with twice its weight of water. The mixture is then exposed to heat, which produces an effervescence, occa- sioned by the escape of deutoxide of azote (nitrous gas). After two days digestion, more nitric acid is added, and the heat continued, until the solution is complete. The so- lution is then evaporated to dryness, whereby a brown- coloured mass is obtained, which is artificial tannin. 7. Artificial tannin agrees very nearly in properties with Properties natural tannin. It differs, however, from the latter, in beine ofartificial soluble without alteration in nitric acid. In composition, it tann'n' diners also by containing azote in addition to the ingredi- ents of natural tannin. 8. Hatchett has found, that even- species of charcoal is susceptible of conversion into artificial tannin by the action 480 VEGETABLE PROXIMATE CONSTITUENTS. Part n of nitric acid. He has ascertained, that it may be formed _Ji__LLL. also by digesting nitric acid upon several substances, which contain a large proportion of carbon; as for instance, indigo and several of the resins. When formed from these sub- stances, however, the tannin is somewhat different from that formed from charcoal. The same chemist has found, that sulphuric acid, digested upon the resins or camphor, con- verts these bodies into a substance analogous to t;innin. Tannin ex- 9. Tannin exists ready formed in many vegetable sub- form^dl^ stances besides nut-galls, but appears to have some variety many in its properties, according to the vegetable from which it plants. js obtained. It is considered, that the oak furnishes the same variety of tannin, which is obtained from nut-galls. More than half the yveight of catechu, or the Japan earth as it is improperly called, is composed of a variety of tannin. Another variety of this substance constitutes a very l.irge proportion of the kino of the shops. In fact, tannin may be considered the peculiar principle, yvhich gives astringenc to vegetable substances. It is to the property of tannin of forming an insoluble compound with gelatin, that its use- fulness in the art ot tanning is to be attributed; since the hide is converted into leather by its gelatin uniting to the tanning principle. SECTION III. OF SUGAR. Sugar is 1. Sugar is a peculiar vegetable substance, chiefly ob- chieflv ob- Gained from the sugar cane, by inspissating its expressed the sugar juice by boiling. By this first preparation, it forms a brown cane. granular substance, constituting an impure sugar. It is pu- rified by being dissolved in water, mixture with lime, and treatment yvith bullock's blood. It is then boiled to a proper consistence, and cleared of its impurities, as they rise to the top, by scumming. It is afterwards poured into unglazed conical earthen pots, whose apices are perforated to allow impurities to separate. The base of the cone is covered with moist clay, which allows a small portion of water gradually to filter through the sugar, with the effect of removing some further impurities. It is now in the state of loaf sugar. Its proper- 2. Sugar, in the pure state, is a white, brittle substance of ties* some hardness, having a very strong sweet taste, but no smell. It is not altered by exposure to air. Water, at the temperature of 48°, dissolves its own weight of it, and boiling water, any quantity. In the form of a saturated so- SUGAR. 481 lution, it is called syrup. It is also soluble in alcohol, but Chap. I. hss so than in water. Its specific gravity is between 1*4 and 1*6. 3. Sugar appears to be capable of combining with both acids and salifiable b is«.s. Sulphuric and hydrochloric acids convert the greater part of it into charcoal. Nitric acid changes it into oxalic and malic acids. 4. When exposed to heat, sugar m> Its, becomes blackish- brown, emiis a.r bubbles and exh des a peculiar s>nell. At a red heat, it bursts into fl unes, which are white with blue edges. 5. By being burnt with chlorate of potash, sugar was Composi- found by Gay-Luss ic and Thenard to be composed of tlon• Oxygen 50-63 Carbon 42*47 Hydrogen 6*90 100 00 6. Besides the common sugar which is obtained from Sugar is of the sugar-cane, and the sugar extracted from the sap of £lff'V'ei,t the sugar-maple and from the beet, which does not appear to differ from common sugar, there are several other spe- cies of sugar, each having distinctive properties. 7. There is a sugar, which differs from comnon sugar in Liqnidsu- being always in the liquid form. It exists in the sugar ^aievx,st? cane, and forms a considerable part of molasses. It exists vegetable also in a number of fruits, such as grapes, peaches, apples,substan- &c. and has been extracted from the stalks of Indian corn. Ce Besides this sugar, the sugar of figs, of grapes, and that which exudes from the fraxinus ornus, a species of ash, are all peculiar sugars. The latter, under the name of manna, constitutes a valuable laxative; and differs from common sugar, in being much more abundantly soluble in alcohol, in yielding saclactic as well as oxalic acid by the action of nitric acid, and in not being fermentable. 8. Starch may be converted into sugar, possessing the Starch tray same properties as the sugar of grapes, by mixture with1*!50"* •> four times its weight of water, and y^th part of its weight gjr"'t0 m' of sulphuric acid, and exposure to a boiling heat for 36 hours, supplying water as fast as it evaporates. The acid is then saturated with lime, and the insoluble sulphate of lime, which becomes formed, separated. The remaining liquid, after concentration by heat, is found to contain a peculiar su- gar. The manner, in which the conversion is effected by this treatment, is not understood. 9. Sugar is undoubtedly one of the most ntritims sub- stances known. It constitutes a very important part of the 3 P 482 VEGETABLE PROXIMATE CONSTITUENTS PahtII. food of most civilized nations. Its uses in pharmacy are OOK • various. Its antiseptic properties make it very useful for preserving different vegetable substances from putrefaction. SECTION IV. OF SARCOCOLL. Sarcocoli, 1. This substance is generally considered to be a gum- anexuda- resin. It is formed by spontaneous exudation from a tree, tion from . , • */-•*-•• t a tree. sa«d to grow m Atrica. In its impure state, it is in the form of oblong globules, from the size of a particle of sand to that of a pea. Its colour is usually yellow, but sometimes reddish-broyvn, and its smell peculiar. About four-fifths of it only consist of pure sarcocoli. It is distinguished from gum and mucilage by being precipitable by tannin. It ap- proaches in its nature to liquorice, and forms, when dis- solved in water, a solution which tastes very like a decoction of this substance. It is sometimes employed in medicine. certain trees SECTION V. OF GUM. Gum ex- 1. Gum is a peculiar vegetable substance, which exudes udes from fr0m certain species of trees in the form of a thin transpa- rent liquid, which gradually hardens by the action of the air. That which is usually employed in the arts and in medicine is an exudation from the mimosa nilotica, a tree which grows in Arabia and Egypt, and occurs in commerce under the name of gum arabic. The gummous matter which exudes from the black cherry tree is composed principally of gum. The gum Senegal is composed almost entirely of this vegetable pi inciple. Its proper- 2. Gum is usually in the form of small pieces, moderately hard, and somewhat brittle while cold. It has generally a yellowish tinge; but when pure, it is perfectly colourless, and possesses some lustre. It has no smell, and hardly any taste. It dissolves in large quantities in water, and forms a solution, usually called mucilage, which is thick and adhe- sive, and may be kept for years without undergoing putre- faction. 3. By exposure to heat, gum softens and swells, but does not melt. It then emits air-bubbles, blackens, and, when nearly reduced to charcoal, gives out a low blue flame. After Ues. SARCOCOLI^GUM—MUCUS. 483 it has consumed, there remains a small quantity of ashes, Chap. I. composed chiefly of the carbonates of lime and of potash. 4. From the experiments of Dr. Thomson, it appears Gum com. that gum has some affinity for the peroxides of mercury ^J *£h and of iron. This chemist found, that gum produced no ides. precipitate in solutions of the alkaline or earthy bases, ex- cept in that of silicain potash. In this latter solution, even though very dilute, he found that a white flaky precipitate was produced. 5. The vegetable acids dissolve gum without alteration, Vegetable but the stronger acids effect its decomposition. Bv sulphuric ac!ds ,||S" acid, it is blackened and converted into charcoal. With hy- unchanged. drochloric acid, it forms a brown-coloured solution, which becomes transparent when diluted with water, but at the same time deposites a charry matter. Nitric acid, slightly heated upon gum, forms a solution, which, upon cooling, deposites saclactic acid. At the same time, some malic acid is formed. If the heat be continued for some time, the gum is at last changed into oxalic acid. 6. Gum is insoluble in alcohol, ether, or the oils; but when triturated with the latter, it renders them miscible yvith water. When alcohol is poured into mucilage, it com- bines with its yvater, and precipitates the gum in soft opaque white flakes. 7. According to Gay-Lussac and Thenard, gum is com- Composi- pOSed of tionofgunf. Oxygen 50*84 Carbon 42*23 Hydrogen 6*93 100*00 8. Gum is very much used in the arts and in medicine. Its uses. It is employed very extensively to give stiffness and lustre to linen, and in calico printing to give consistency to the colours. It is nutritious, and may be used as a nutriment in diseases, yvhen almost every other substance would be im- proper. In the composition of many medicines, it is of indispensable utility. SECTION VI. OF MUCUS. 1. This vegetable constituent had been confounded with Mucus, di.- gum, until Dr. Bostock proved its peculiar nature experi- t*">R"i*ed' mentally. There are a number of varieties of it, which mav 'gnFSL be obtained from the roots, leaves and seeds of different took. 484 VEGETABLE PROXIMATE CONSTITUENTS Part 11. plants. It may be obtained, in its purest form, from flax- Boqk II seff* jt mav be extracted also, yvith some differences in properties, from quince s< eds and from the root of the hyacinth. It exists in considerable quantities in mallows, in the leaves of the althaea, in mam of the fuci, but in a still greater number of the lichens. 2. Mucus is distinguished from gum, in being preci- pitated copiously from us solution in water by acetate of lead; in being throyvn down by alcohol in white flakes, yvhich do not render the liquid opaque, as happ ns under similar circumstances yvith gum; and in remaining unalter- ed upon the addition of silicated potash. SECTION VII. OF JEI LY. Jelly may 1. Jelly appears to be a peculiar vegetable substance. It be obtained may be obtained from ripe blackberries, currants, oranges, raTfruhs6" lemons, gooseberries, and similar fruits, by allowing their expressed juice to gelatinize, and afterwards to drain upon a fine sieve. In this way thi acid parts separate and pass through the si» ve, while the jelly in a tolerably pure state remains behind. It is then washed with a little cold water, to separate any adhering acid. Its proper- 2. Jelly, upon dry nj^, contracts considerably in bulk, and ties. becomes a h ,'the is capable of assuming. It is obtained by evaporating the ^""!',1'f of aqueous infusion ot the plant to the consistence of hon> y; saffron> and and in that state, digesting it in alcohol, filtering the alco- holic solution, and evaporating to dryness. The dry mass is pure polychroite. It has an intensely yellow colour. It is very soluble both in alcohol and water, but scarcely so in sulphuric ether. When exposed to the air, it absorbs mois- ture and is converted into a viscid liquid. II. Hematin is the name given by Chevreul to the sub- hematin, stance, first recognised by him to be of a peculiar nature,.the vh-n exposed to the air, is liable to putrefaction. W.ien mix d with sulphate or hydrochlorate of alumina, a precipitate falls, consisting of alumina and extractive combined. It is precipitated from its solutions bv hydrochloric or sulphuric acid. It unites with the alkaline bases, as well as with most of the salifiable bases of the third class, usually called me- tallic oxides, forming insoluble compounds. Extractive, 2. Extractive is different in its properties, according to did" rem as the vegetable substance from which it may be obtained. It from"diffe- exists in the sap of almost all the trees which have been rent *ege- examined. It is thrown down from this vegetable liquid u ' bv means of chlorine, or by evaporation at a sand heat. It is a constituent also in all barks, as far as they have been the subject of experiment. It almost always accompanies tannin. 3. Extractive is present in catechu. It mav be obtained from this astringent substance by repeated washings, until the water yvhich comes off gives no indication ot the pre- sence of tannin upon the addition of gelatin. What remains will consist of extractive. 4. Senna dissolves in tvvice its weight of cold yvater, and forms an infusion, which contains, besides a considerable pro- portion of carbonate of lime, sulphate of potash, carbonate of magnesia and a little silica, a certain q tantity of extrac- tive. This may be made evident by m ms of hydrochloric acid or chlorine, either of which throws down the extractive somewhat altered in its properties. The extractive of sen- na, whin placed upon burning coals, emits a thick smoke and exhales an aromatic smell, the residuum being a spongy charcoal. EXTRACTIVE—EMETIN. 489 5. Peruvian bark was found by Fourcroy to contain a Chap. I. peculiar extractive. It is separated, by treating the watery extract of the bark with alcohol. The alcoholic solution thus obtained, by evaporation, affords the extractive. When dry, it is a black and brittle substance, which breaks with a polished fracture. Its taste is bitter. It is insoluble in cold yvater, but dissolves in hot water and in alcohol. SECTION XIII. OF EMETIN. 1. Emetin is the name given to the peculiar substance, Emetin, discovered in ipecacuanha by Majendie and Pelletier, tothe l,.ecu.,!' ..... * , . J :' ' arpnnci- yvhich this vegetable owes its emetic property. pieofipe- 2. It is obtained in the following manner. An alcoholic cacuanha' solution of ipecacuanha which had previously been digested in sulphuric ether, is evaporated to dryness; and the dry mass obtained, dissolved in water, and treated with a solu- tion of acetate of lead. A precipitate is thereby formed, composed of emetin and oxide of lead. This precipitate, be- ing washed and diffused in water, is subjected to the action of hydrosulphuric acid gas (sulphuretted hydrogen). This acid gas throws down the lead, and the disengaged emetin dissolves in the water. It is afterwards obtained from its aqueous solution by evaporation to dryness. 3. Emetin is a broyvnish-red uncrystallizable substance, Its proper in the form of transparent scales, destitute of smell, andtics" having a taste, bitter and somewhat acrid, but not in the least nauseous. It is soluble both in yvater and in alcohol. It is not affected by any heat below the boiling point; and above that temperature, it does not melt, but swells, black- ens, and is decomposed into yvater, carbonic acid, a little oil, and acetic acid. 4. It is not acted on by sulphuric acid in a diluted state but when concentrated, it is charred and destroyed by its' action. Ni'tric acid forms with it a red-coloured solution gradually becoming yellow, and depositing crystals of oxalic acid. Hydrochloric and phosphoric acids dissolve it with- out alteration. Acetic acid is one of its best solvents. Ace- tate of lead precipitates it from solutions in abundance. 5. When given to the amount of half a grain, it proves _t3 act[oil violently emetic. Its operation is followed by sleep. In do- upon !he „- ses of twelve grains, or even much smaller ones, it proves nimal ecr' fatal. Upon dissection after death produced by it, it was R°m7' found that the lungs and intestinal canal were inflamed 3Q 490 VEGETABLE PROXIMATE CONSTITUENTS. Part II. Book U. SECOND SET. SUBSTANCES INSOLUBLE LY COLD WATER, BUT PAR- TIALLY SOLUBLE IN HOI. SECTION I. OF MORPHIA. Morphia, 1. Serturnf.r gives the name of morphia to a peculiar the narco- substance, yvhuh he discovered in 1817 in opium, and to tic pnnci- i-uu- ii i- • • • pie of opi- which this vegetable medicine owes its narcotic properties. um. Precisely the same substance has been ascertained by Vau- quelin to exist in the opium from the garden poppy. 2. This substance exists in opium combined wi h a pe- culiar acid, which Scrttirner calls meconic* acid.f It is extracted by the following process. Rub together eight ounces of pulverized opium with two or three ounces of strong acetic acid and a little water, until the whole has assumed the consistency of a soft pap. Pour upon the mix- ture, thus formed, two or three pounds of water, and strain the whole through a cloth. A coloured liquid passes through, which contains acetic acid and meconate of mor- phia, a little morphia combined with extractive, and neu- tralized free extractive. Upon the addition of caustic ammonia, morphia, contaminated with extractive, is thrown down in abundance. To separate the extractive, digest the impure morphia in a very small quantity of alcohol. This li- quid takes up the extractive and leaves the morphia behind. its proper- «•*• Morphia is a colourless crystallizable substance, spa- ties, ringly soluble in boiling water, but forming solutions rea- dily with alcohol or ether which have a bitter taste. It combines with many of the acids, forming neutral com- pounds, and appears, in some respects, to bear considerable analogy to the alkaline salifiable bases. When exposed to a gentle heat, it melts and assumes someyvhat of the appear- ance of melted sulphur. It burns easily in the open air; but when heated in close vessels, it is converted into a solid re- sinous black mass, having a peculiar smell. It has not been analyzed, but St rtiirner considers it to be a compound of oxygen, carbon and hydrogen. its action 4. Morphia is found to exert a powerful action upon man^ k"* the animal system. When given in the dose of half a grain, tem. * From finxov, the poppy. f In a late number of the Annales de Chimie (Nov. 1818), "Vauquelin attri- butes the discovery of morphia and meconic acid to Seguin. He certainly proves that Seguin insulated and characterized both these substances, although fie did not appropriate to them peculiar names. MORPHIA-STRYCHNIN. 491 dissolved in spirits, to a young person, it produced flushing Chap.I. of th< face, and an increase of muscular power. The same dose, repeated in half an hour, occasioned a dull pain in the head, giddiness, stupor and nausea. A third dose of half a grain bang given, all the effects of the substance were so much increased, as to create alarm for the safety of the subject of the experiment. SECTION II. OF STRYCHNIN.* 1. Pelletier and Caventou have succeeded in obtaining Strychnin, the poisonous principle of the nux vomica and St. ignatius's jMeJ2J; bean in a separate state, which proves to be the same in cipie of the both. The plants which furnish these substances belong to ""*™raj_ the genus strychnos. The wood of another species ot this ignaarUus's' genus (s. colubrina) has yielded, to these chemists, the bean. same peculiar principle. It is in consideration of these facts, that Pelletier and Caventou have named the peculiar prin- ciple strychnin. 2. Strychnin is a white and granular substance, scarcely Its proper- soluble in water. Notyvithstanding its sparing solubility, itties* possesses a very intensely bitter taste. The impression, which it leaves upon the mouth, has been compared to that occasioned by the metallic salts. It is entirely destitute of smell. It restores the colour of vegetable blues, previously reddened by acids. It suffers no alteration in the air. When exposed to a heat gradually increased, it is decomposed at a lower temperature than is sufficient to destroy the genera- lity of vegetable substances, and charcoal is developed. The products of its decomposition by heat are an empyreumatic oil, some acetic acid, carbonic acid, bihydroguret of carbon (carburetted hydrogen) and a bulky charcoal. It is conse- quently composed of oxygen, hydrogen, and carbon. 3. Strychnin possesses the properties of a salifiable base, inasmuch as it forms yvith acids neutral compounds, which are transparent, soluble, and crystallizable. A number of salts have already been formed from it, and their proper- ties noticed by Pelletier and Caventou. It forms a peculiar salt with nitric acid, when diluted; but is changed to a red colour and altered in its properties by the action of this • It has already been mentioned, that Dr. Thomson's classification of vegeta- ble proximate constituents is adopted in this work. Strychnin, however, was not known when the last edition of this chemist's work was put to press; and 1 have placed it where it is most probable Dr. Thomson would have placed it himself. 492 VEGETABLE PROXIMATE CONSTITUENTS. Part IL Book II. Its action upon ani- mal life is that of an energetic poison. acid in a concentrated state. The acid appears to oxidize the strychnin, yvhich, after being thus altered, still retains its salifiable property, though less alkaline in its nature. By the repeated action of nitric acid, it gradually becomes less and less alkaline and bitter, and at last loses its deleterious properties. 4. Strychnin is united, in the nux vomica and bean, with a peculiar acid, yvhich is called, by its discoverers, igasuric acid, from the Malay name of the bean. 5. Strychnin is a very violent poison. Half a grain of it, blown into the throat of a rabbit, killed the animal by teta- nus in five minutes. Upon introducing the same quantity of the poison into an incision on the back of a rabbit, death yvas produced by tetanus in three minutes. The salts form- ed from this substance are found to be even more power- ful; yvhich circumstance is attributed to their solubility. Nitrate of strychnin, given to a rabbit in the dose of a quar- ter of a grain, caused tetanus in tyvo minutes, and death in three more. Strychnin, when oxidized, becomes less poi- sonous, and by the repeated action of nitric acid is rendered at last harmless. Its effects are counteracted, in an eminent degree, by the use of opium. Majendie has given it a trial as a medicine, and observed the same effects from its use, as from that of the nux vomica, the bean, or the upas of Java; stimulating especially the spinal marrow, and indu- cing a true tetanus. It is, however, more powerful than these substances. When exhibited in closes of a quarter of a grain, in a case of muscular debility, occurring in a man of sixty years of age, in consequence of a cerebral disease, it induced several attacks of tetanus*. SECTION III. OF ASPARAGIN. Asparagin, 1. Asparagin is the name given by Dr. Thomson to the a peculiar peculiar vegetable substance, which was noticed by Vauque- extracted lin and Robiquet to be deposited in crystals, when the ex- fromaspa- pressed juice of asparagus, evaporated to a syrup, is allowed ragus. to stand. These crystals are white and transparent, and have a cooling and slightly nauseous taste. They are very soluble in hot water, but sparingly so in cold. In alcohol they are insoluble. * The facts given in the above section were taken from a paper on strychnjn by Pelletier and Caventou, which appeared towards the close of the last year in the Annates de Chimie. ASPARAGIN—cerasin—inulin. 493 Chap. I. SECTION IV. OF CERASIN. 1 Cerasin is the name, by which Dr. John distinguishes Cerasin has a peculiar vegetable substance, heretofore confounded with J*^^°nr.e gum, and which possesses the following properties. It is founded harder than gum, but has the same appearance and taste as with gum. this vegetable substance. When put into water, it imbibes this liquid, and becomes transparent and gelatinous, but does not dissolve. It may be dissolved in boiling water, but it precipitates as the liquid cools. It is insoluble in alcohol and ether. 2. The only vegetable substances, mentioned by Dr. itisfurnish- Thomson as furnishing cerasin, are the gum tragacanth, and ed DJ 8um the different gums which exude from the cherry and plum whfch'b'the trees, as well as from the almond and apricot. hardened 3. Gum tragacanth is the juice, hardened in the sun, ofJtrece^° a the astragalus tragacantha, a thorny shrub, which grows in Candia and other islands of the Levant. It may be consi- dered as pure cerasin. When put in water, it imbibes a large portion of this liquid, encreases in volume, and forms a jelly-like mass. By agitation, this mass may be so diffused, as to form a liquid, having the appearance of whey, and which, upon rest, becomes clear again. When a solution of gum arabic is poured into the whey-like liquid, so far from forming any union with the tragacanth, the latter sub- sides much faster than it otherwise would do. When treated with nitric acid, it yields abundance of saclactic acid. 4. The gummous exudations from the trees already Gummous mentioned are found by Dr. Thomson to be compounds ofexudations i j • r are mix- real gum and cerasin. turesof gum and _ cerasin. SECTION V. OF INULIN. 1. Dr. Thomson has given this name to the peculiar sub- lnuiin,a stance, which Rose discovered in the roots of the inula he- PK«u-'ar lenium (elecampane.) It may be obtained by allowing their fuVrishecT decoction to stand for several hours. The powder which Dv e'ecam- will be found precipitated is inulin. pane- 2. Inulin is insoluble in cold water, but may be diffused through this liquid, so as to have the appearance of milk. It is readily soluble in hot yvater. Alcohol produces no change in the aqueous solution yvhen first added, but aftenvards pre- 494 VEGETABLE PROXIMATE CONSTITUENTS. Part II. cipitates the inulin in the form of a bulky white powder. BooK 1L Gum, similarly treated, would remain milky for several days. SECTION VI. OF STARCH. Starch; 1* This peculiar vegetable substance may be readily ob- ho» obtain-tained trom wheat flour, by forming it into a paste yvith wa- wheat flour.ter*. and kneading it continually under a stream ot water, until this liquid runs off colourless. The water is found to have separated a portion of the flour, and to have assumed a milky appearance. Upon standing, it deposites a white powder. This powder is starch. What remains of the flour not affected by the stream of water is gluten, a substance which will be described hereafter. Process 2* Starch is obtained by the manufacturer by the follow- pursued by ing process. Wheat is steeped in cold water, until the grains facturer.U ^aVfc DeCOme so s°ft as to yieU* a milky juice when squeezed. It is then put into coarse linen sacks, and subjected to pressure in vats filled with cold water. The milky juice is in this way squeezed out of the grains, and becomes dif- fused in the water. The wheat is repeatedly steeped in wa- ter and subjected to pressure, as long as it yields any of the milky juice; after which the sacks and their contents are removed from the vats. The starch soon subsides, and the water which covers it gradually undergoes a fermentation, during which a portion of alcohol and vinegar is formed. The vinegar dissolves the impurities, and leaves the starch untouched. The supernatant liquid is then drawn off, and the starch washed, and dried at a moderate heat. During drying, it cracks into small columnar masses, possessing considerable regularity. It is now in the state in which it is used for stiffening linen and cotton cloth, and for other pur- poses. Properties 3. Starch has a fine white colour, scarcely any smell, and of starch. veiy iittie taste. When exposed to air in a dry state, it un- dergoes no alteration. It is insoluble in cold water. With hot water, it may be formed into a kind of jelly, which can be diffused in boiling water, so as to remain suspended for a longer or shorter time, but does not dissolve. It is per- fectly insoluble in alcohol, even when assisted by heat. It is insoluble also in ether. None of the salifiable bases, as far as they have been tried, is capable of precipitating it, ex- cept barytes. Its most characteristic property consists in its being thrown doyvn, combined yvith tannin, from all solu- STARCH. 495 tions by infusion of nutgalls. It constitutes a very deli- Ch^l cate trst of the presence ot iodine. 4. Sulphuric acid dissolves starch slowly, and developes Effects of a verv bulky charcoal. When diluted and heated, this acid *etJ™1*" dissolves it without alteration. Diluted nitric acid dissolves upon it. starch slowly, and forms a green-coloured solution, on the surface of which then swims a white matter, not acted upon by the acid. This peculiar mode of action of nitric acid has been taken advantage of, to detect starch in vegetables. Strong hydrochloric acid dissolves starch slowly, and yvith- out effervescence. When the proportion of the starch does not exceed j^th of the acid, the solution is transparent and colourless; but when in larger amount, it loses, in a degree, its liquidity, and becomes of a brown colour. 5. When starch is thrown upon a hot iron, it melts, blackens, froths and swells, and burns with a bright flame, emitting a large quantity of smoke; but it does not explode, or emit the peculiar smell, which sugar does under similar circumstances. 6. According to an analysis by Gay-Lussac and Thenard, Composi- starch is composed of tion ?f w i „ w_ starch. Hydrogen 6'77 Carbon 43*55 Oxygen 49*68 100*00 7. A very large proportion of the vegetables, employed as starch is food by man, contain starch. It may, therefore, be justly b,g!,,y nu- considered a highly nutritious vegetable principle. Its me- dicinal properties are those of a demulcent. It is often ad- vantageously used in diarrhoea and dysentery, both by the mouth and in the shape of clyster, more particularly in the latter form, when there is irritation in the rectum. The parts of plants, in yvhich it is most abundantly found, are their seeds and bulbous roots. The following table exhibits the proportion of starch contained in one-hundred parts of the seeds, which constitute the greater portion of the vege- table food of man. DIFFERENT VEGETABLE SEEDS. Flour of yvheat (triticum hybernum) rye (secale cereale) barley (hordeum vulgare) Seeds of orysa sativa (riceJ pisum sativum (pea) _______phaseolus vulgaris (kidney bean) Quantity ot starch per cent. 74*5* 62 67f from 84 to 85 33 36 • According to Proust. Thomson's Annals xii. 202 11 hud by the Annals of Philosophy, that Proust has lately subjected barley 496 VEGETABLE PROXIMATE CONSTITUENTS. 8. The bulbous root of the potatoe (solanum tuberosum) was found by Einhof to yield 15 per cent, of starch. 1 he m< thod of obtaining it, is to grate down the potatoe to a 15 per cent. PU*P* anc* t0 wash it repeatedly with water on a fine sieve. of starch, The water carries with it the starch, and must be received in proper vessels and allowed to settle. This starch differs from wheat starch, in forming a thicker paste with water, in having a perceptible crystallized appearance, and in being specifically heavier. 9. The sago, salop and tapioca of the apothecaries, sub- stances so frequently ordered as diet for the sick, are all different varieties of starch. Part II. Book II. The pota- toe contains vhich dif- fers from ■wheat starch. SECTION VII. Indigo, ob' tained trora several plants. Process described. Indigo of commerce described. OF INDIGO. 1. Indigo of commerce is the produce of several species of plants, which grow in the West Indies and South Ame- rica. These are the indigofcra argentea, or wild indigo, the indigofera disperma, or Guatimala indigo, and the indigo- fera tinctoria, or French indigo. The first mentioned yields the best indigo, but in smallest quantity; the last named, the greatest. 2. The indigo is separated from the plants by steeping them in water, until they undergo a species of fermentation, at yvhich time, they communicate a green colour to the wa- ter. The water is drawn off and agitated, by which means blue floculi appear, and the whole becomes curdled. Lime yvater is now added, which is supposed to act by prevent- ing putrefaction, and the floculi are allowed to subside. The water is then drawn off, and the pigment placed in linen bags to drain; after yvhich, it is put into little square boxes and dried in the shade. 3. The indigo of commerce is a light friable substance, of a deep blue colour and compact texture; its colour, ho\v- ever, varies somewhat with the different modes of its pre- paration. That which is lightest is most free from impurities, and is therefore best. to analysis, and finds it to contain only 32 per cent of starch. This chemist con- ceives, that he has detected a new vegetable principle in this grain, in the amount of 55 per cent, which he calls hordein. (Annals, xii. 201.) INDIGO—GLUTEN. 497 4. According to Bergman, the indigo of commerce is Chap. I. composed of Pure indigo 47 Gum 12 Resin 6 Barytes lime and silica 22 Oxide of iron 13 100 Thus it appears that more than half the weight of the indigo of commerce consists of impurities. 5. Pure indigo is a soft powder of a deep blue colour in- Pure indigo dining to purple, and destitute of taste or smell. It under- desenbed- goes no alteration in the air. It is insoluble in water. When ex- posed to heat, it emits a bluish-red smoke, and at last burns with a faint white flame. The residuum is a portion of ashes. 6. Diluted sulphuric acid, digested upon common indigo, Effects of has no other effect than to dissolve the impuritits; but the thest™n" • i l . ■. r . , Rer acida same acid, when concentrated, dissolves pure indigo with upon it. the evolution of heat, and forms the solution, known by the name of liquid blue. Nitric acid, by its action upon it, pro- duces tannin and bitter principle, and also, by peculiar ma- nagement, benzoic acid. SECTION VIII. OF GLUTEN. 1. This substance may be obtained from wheat flour, by Gluten, forming it into a paste with water, and kneading it under a novobtaia- jet of water, until this liquid comes off colourless. The starch XST is thereby washed off, so that nothing remains but pure gluten. flour- 2. Gluten is a ductile, exceedingly tenacious and elastic Its proper- substance of a grey colour. When spread very thin, it isties- nearly white and has considerable resemblance to tendon or animal membrane. Its smell is peculiar, and its taste very slight. When exposed to the air, it at first assumes a brown colour, and becomes, as it were, covered by a coat of oil. Afterwards it becomes dry, in which state it has some re- sem bance to glue; for it is now slightly transparent, has a dark brown colour, and is pretty hard and brittle, break- ing with a fracture like glass. 3. Gluten in its fresh state always contains a certain quan- when titv of water, which it holds with great obstinacy, and to^h-con- which it owes its elasticity and tenacity. When macerated tains watev' in cold water for a considerable time, an opaque liquid, sus- pending small films, is formed. This liquid, by repeated 3 R 498 VEGETABLE PROXIMATE CONSTITUENTS PautII. Book U. Moist glu- ten putre- fies upon keeping. Effects of the stron- ger acids upon glu- ten. Effects of drying and of heat Gluten re- sembles animal matter. It is found in a great variety of highly nu- tritious sub' stances. filtration, may be rendered transparent, but still it contains a small proportion of gluten. From this it appears, that this vegetable substance is somewhat soluble in water. When the transparent solution is heated, the gluten separates in yellow fl.ikes. 4, When gluten is kept moist, it very soon undergoes a kind of putrefactive fermentation. It swells, emits bubbles of air consisting of hydrogen and carbonic acid, and exhales a putrid odour, similar to that which attends the putrefac- tion of animal substances. When continued in the same state for 24 days, the gluten becomes converted into a kind of paste, of a greyish-white colour, which is denominated fer- mented gluten. If the exposure be still continued, the gluten at last acquires the smell and taste of cheese. 5. Fresh gluten does not dissolve in alcohol, but is thrown down from its aqueous solution by this liquid. It is insolu- ble in ether also. 6. Concentrated sulphuric acid, when poured upon gluten, renders it at first violet-coloured, but at last black; in- flammable air is evolved, and water, ammonia and charcoal formed. When nitric acid is heated upon it, azotic gas is evolved, oxalic and malic acids are formed, and a number of yellow-coloured oily ftXkcs make their appearance. When the infusion of nut-galls is added to a solution of gluten, a yellowish-brown precipitate appears, which does not dis- solve by the application of heat. 7. When moist gluten is suddenly dried, it swells ex- ceedingly. When dry gluten is exposed to heat, it cracks, swells and melts, then blackens and exhales a fetid odour, burning precisely like feathers or horn. 8. Gluten approaches, in many respects in its nature, to animal matter. Yielding ammonia by destructive distillation and by fermentation, one of its constituents must be azote. Its other component parts are oxygen, hydrogen and carbon. 9. Gluten, besides existing in large proportion in wheat flour, which is thereby so well fitted to form bread, is found in many other nutritious vegetable substances, in greater or less amount. The principal of these are rye, barley, peas, and beans, as well as chesnuts, horse-chesnuts and acorns. It has not been discovered in the potatoe. After being fer- mented, it forms, by trituration with a small quantitv of al- cohol and afterwards mixture with a considerable quantitv, a solution, which constitutes an excellent varnish for paper or wood, as was first ascert ined by Cadet. This same che- mist ascertained, that fermented gluten formed a very; good ground for paint. It is also useful for the purpose of ce- menting pieces of china. POLLENIN—FIBRIN—OILS. 499 Chap. I. SECTION IX. OF POLLENIN. 1. This is the name given by Dr. John to a peculiar sub- Pollenin,« stance, which may be extracted from the pollen of the pinus J„£jJlnce abies, pinus sylvestris and lycopodium clavatum, and which extracted is supposed by him to be the characteristic constituent of fromtho^ the pollen of every species of plant. the pine. 2. Pollenin is a yellow substance, destitute of taste and smell. It is insoluble in water, alcohol, ether or the oils. When exposed to the air, it very soon acquires the odour and taste of cheese, and afterwards runs into the putrefac- tive fermentation, forming a considerable quantity of ammo- nia. It is closely allied to gluten in its properties. SECTION X. OF FIBRIN. 1. Fibrin must always be considered as a substance ra-fibrin ex- ther of animal than of vegetable origin. But as a substance ^cttfthe has been detected by Vauquelin in the milky juice of the papawtree. papaw tree (carica papaya), which appears to be the same as the fibrin of the blood; fibrin, although previously consi- dered exclusively of animal origin, must be mentioned here to complete the enumeration of vegetable proximate consti- tuents. The description of this substance will be deferred, until treating of fibrin as an animal constituent. THIRD SET. SUBSTANCES WHICH MELT WHEN HEATED, IF NOT ALREADY LIQUID, AND BURN LIKE OILS. SECTION I. OF OILS. 1. This class of vegetable constituents has been divided Oils are di- into fixed and volatile oils. vi(led '"to 2. The fixed oils are found very rarely in any parts of Sue"1 vegetables except their seeds, which are almost always Di- cotyledonous. Olive oil is an exception to this rule, being extracted from the pulp which surrounds the stone of the fruit. On the other hand, the volatile oils are found in every part of the plant, except the cotyledons of the seeds. 500 VEGETABLE PROXIMATE CONSTITUENTS Part II. These latter oils are verv numerous, existing in fact in all Book ii. pi,,nts having a peculiar'odour, which in every case de- pends upon their presence. Some account of the volatile and fixed oils has already been given. The subject is resumed merely for the purpose of making the enumera- tion of the proximate constituents of vegetables complete. Wax may be extract- ed from se- veral plants. Bees-wax described. Wax eonv bines with fixed oils. Composi- tion of wax SECTION II. OF WAX. 1. Wax may be extracted in considerable abundance from several plants. The greatest quantity of this sub- stance, however, is fabricated by bees from vegetable ma- terials. Bees-wax will be first described, and afterwards the principal varieties of this substance will be noticed. 2. Bees-wax, when pure, is of a whitish colour, and nearly destitute of taste and smell. In its common state, it is yellow, and has a pretty strong aromatic odour; but it loses both colour and smell by bleaching, which is effected by exposing the wax, in thin ribands, for some time tothe at- mosphere. It is insoluble in water and in cold alcohol; but alcohol, assisted by heat, is capable of dissolving ivth ot its weight of it. When the solution cools, the greater part ot the wax falls down, and the remainder may be precipitated bv water. Dr. John has ascertained, that one portion of bees-wax is insoluble in boiling alcohol, and has properties distinct from the soluble portion. The insoluble portion he calls myricin, and the soluble portion, cerin. 3. Wax combines readily with fixed oils, and forms com- pounds of more or less consistency, according to the pro- portions used. This combination forms the application made to sores, which is known by the name of cerate. 4. Wax combines with potash, soda and ammonia, and forms compounds analogous to soaps. 5. Acids have but little action upon wax. Chlorine pro- duces no other change upon it than to destroy its colour when in the unbleached state. Its insolubility in acids fits it as a lute to confine corrosive acids, and for stopping bottles rontaininc* these substances. 6 According to Gay-Lussac and Thenard, wax is com- Oxygen 5*544 Hydrogen 12*672 Carbon 81-784 100-000 WAX—CAMPHOR. 5Q1 7. It has been ascertained, that the varnish, which covers Chap. 1. the upper surface of the leaves of many plants, consists of Varnisk e0. a substance, which possesses all the properties of bees-wax. veringsome It may be separated by the following process: Digest the ^v"of,s a bruised leaves, first in water and then in alcohol, until every wax. thing soluble is taken up. Treat the residuum with six times its weight of water of ammonia, as long as this liquid will dissolve any thing. Then decant the solution formed, and, after filtering it, add diluted sulphuric acid, more than suf- ficient to saturate the ammonia, stirring the whole constant- ly. A precipitate, in the form of a yellow powder, will fall, which, after being carefully washed, .and melted over a gentle fire, is the substance in question. 8. Myrtle wax is obtained from the myrica cerifera, a Myrtle- shrub which grows abundantly in Louisiana and other parts *** of the United States. The wax is separated by boiling the berries, which are covered with a coat of it, in water. The boiling water melts the wax, which is skimmed off its sur- face. It is then passed through a cloth, dried, melted again, and cast into cakes. This wax is insoluble in water, and but sparingly soluble in alcohol. Its specific gravity is greater than that of bees-wax. It forms compounds with potash, soda and ammonia, very similar to those formed by bees-wax. When strongly heated, it burns with a clear white flame, emitting an aromatic odour. 9. Wax is of indispensable utility in pharmacy. It enters Uses of into the composition of almost all the cerates, ointments and ^armacy. plasters, employed in practice. SECTION III. OF CAMPHOR. 1. Camphor is obtained from the laurus campnora, a Camphor, tree which grows in Japan, and other parts of Asia. It J^"^ comes to Europe and America in a crude state, formed by which distilling the wood of the plant with water. It is refined for jJJ££ the purposes of medicine by a second distillation m glass vessels 2. Camphor, after being refined, is a white brittle sub- Its proper- stance, possessing a strong acrid taste, and peculiar aro- es- matic smell. It is insoluble in water, but dissolves readily in alcohol, from which it may be precipitated by water. It is soluble also in both fixed and volatile oils. It is not act- ed on by potash or soda, whether pure or m the state ot carbonates. 502 VEGETABLE PROXIMATE CONSTITUENTS Part II. Book II. Camphor of volatile oils. Artificial camphor, formed by the action of hydro- chloric acid on oil of turpentine. Properties of artificial camphor. 3. Most of the acids dissolve camphor, and generally it may be precipitated from the r solutions unaltered. 4. When camphor is exposed in an open vessel in warm weather, it evaporates completely. It is volatilized also, when exposed to heat; but if the heat be suddenly applied, it may be melted before it evaporates. It is very inflamma- ble, catching fire readily and emitting a great deal of flame, and leaving no residuum. When burnt in a large globe filled with oxygen gas, and containing a little water, the products are camphoric acid and carbonic acid which impregnate the yvater, and charcoal which covers the inner surface of the globe. 5. There are several kinds of camphor, besides that which has just been described. The principal ol them are the cam- phor of volatile oils, and the camphor formed by treating oil of turpentine with hydrochloric (muriatic) acid. 6. The camphor of volatile oils exists in almost all these bodies. It may be obtained by subjecting them to various degrees of cold, exposed to the open air: the oil gradually evaporates, and the camphor is left behind. 7. Artificial camphor is made by passing hydrochloric acid gas into a vessel containing oil of turpentine. The gas is absorbed, and the oil becomes hot, is increased in bulk, and its colour changed to dark brown. After standing for 24 hours, the oil deposites crystals of artificial camphor. These crystals at first have a slight odour of oil of turpen- tine. To remove this smell, they must be sublimed, mixed yvith their weight of charcoal powder, wood-ashes or quick- lime. 8. When thus purified, artificial camphor has a smell re- sembling that of common camphor, but not so strong. Its taste also is similar to that of common camphor. It swims on water, and may be burnt upon its surface, as is the case with natural camphor. It dissolves completely in alcohol, from which it may be precipitated by water. Nitiic acid of the specific gravity of 1*261 has no action upon it, although this acid dissolves readily common camphor. Concentrated nitric acid, however, dissolves it with the emission of deu- toxide of azote (nitrous gas), and the solution formed is not precipitated by the addition of water. Hence it would appear, that artificial camphor resembles common camphor in every particular, except in the action of nitric acid. BIRD LIME—RESINS. 503 Chap. I. SECTION IV. " OF BIRD-LIME. 1. The viscid matter, which covers the epidermis of Bird-lime, the robinia viscosa, has been ascertained by Vauquelin to °btained be a peculiar vegetable substance. The substance called SofrT bird-lime, by an analysis of Bouillon la Grange, is found binia- to owe its peculiar properties to the presence of a body, very analogous to the peculiar viscous principle just men- tioned. It is on this account, that Dr. Thomson proposes to call the vegetable principle itself by the name ot bird-lime. 2. The biro-lime, which exudes spontaneously from plants, its proper is a green adhesive substance, destitute of taste or smell. Itties- softens between the fingers, to which it sticks with great obstinacy. It is insoluble in yvater, and in alcohol when cold; but it dissolves in hot alcohol. It combines readily with oils. Ether dissolves it with facility, without the assistance of heat. 3. Artificial bird-lime is usually prepared from the middle Artificial bark of the holly. This bark, after being boiled six or eight bn. Dragon's [3.] Dragon's Blood.—Almost all the dragon's blood blood. UStCi in medicine comes from the East Indies, and is the produce principally of the calamus draco. It is also furnish- ed by the pterocarpus draco, a native tree of South Ame- rica, whence it was formerly frequently exported to Spain. It is a brittle, tasteless, inodorous substance, insoluble in water, but almost entirely soluble in alcohol. The alcoholic solution is of a fine deep red colour, and is sometimes used to stain marble. It is fusible and combustible. By the ac- tion of nitric acid, it is converted into benzoic acid and artificial tannin. SECTION VIII. OF GUM-RESINS. Characters 1. The gum-resins may be distinguished by the follow- oi the gum- jng characters: they are solid and usually brittle substances, of a fatty appearance, and opaque or but imperfectly trans- GUM-RESINS. £flfl parent. They are not fusible as the resins are, neither are Chap I they so combustible. When exposed to heat, they soften-----:— and melt. Almost all of them have a strong smell, and an acrid taste. They are but partially soluble in water, with which they form a permanent mixture, always opaque, and generally of a milky app. arance. They form with alcohol, transparent solutions, which are rendered turbid by the ad- dition of water. The strong acids convert most of them into tannin and charcoal. They are usually specifically heavier than the resins. They have been considered to be composed of gum and resin; but all their properties do not accord with such a supposition. They all contain a volatile oil, or a substance intermediate in properties between an oil and a resin. It is to this constituent of them, that their property of forming an opaque solution with water is to be ascribed. The best knoyvn of the gum-resins are the following: The chief [1.] Galbanum.—This substance is the milky juice, hard-Sum-resiin ened by exposure to the air, of the root of the bubon gal- ^Gaiba- banum, a native plant of Africa. It is brought from the nuin- Levant in pieces, composed of tears agglutinated together, which have a yellowish or white colour. It has an acrid and bitter taste, and a peculiar smell. It forms a milky so- lution with water. It is partially soluble in alcohol. [2.] Ammoniac—This substance, which is brought from 2. Ammo- the East Indies, is the produce of an unknown plant. It is niae- composed of small pieces agglutinated together, and has a yellowish white colour. It has a nauseous sweet taste, mix- ed with some bitterness. Its smell resembles that of galba- num, but is more pleasant. Part of it is soluble in water, yvith yvhich it forms a milky solution. More than half its weight dissolves in alcohol. [3.] Aloes.—This gum resin is the inspissated juice of a 3. Aloes. variety of the aloes perfoliata, a plant which grows in the island of Socotora in the East Indies. It has a resinous ap- pearance, a reddish-yellow colour, a bitter taste, and an aromatic smell. It has been found by Braconnot to contain a peculiar principle, similar to that which was detected by Vauquelin in the febrifuge barks. ^[4.] Olibanum—(Frankincense.)-----This gum-resin is4.0liba- brought from Arabia and India. That from Arabia is mostnum' esteemed. It remains doubtful what plant yields this sub- stance. It is brittle and semi-transparent, has a whitish- yellow colour, and an acrid and aromatic taste. When burnt, it diffuses an agreeable odour. When heated, it melts with difficulty, but burns with brilliancy, leaving some white ashes. 510 VEGETABLE PROXIMATE CONSTITUENTS. Pa»t II. [5.] Sagapenum.—It is not certainly known what plant J^£lJL_yields this gum-resin. The substance itself is brought from 5. Sagape- Alexandria, and is composed of tears agglutinated together. num. jt nas a yellow colour, a hot and bitter taste, and an allia- ceous smell. It is but sparingly soluble in water, but dis- solves almost entirely in alcohol. 6. Assafe- [6.] Assafxtida.—This is the hardened juice of the root tida. of the ferula assafattida, a native plant of Persia. It occurs in commerce, in the form of small grains of different co- lours, as whitish, reddish, violet and brown. It has an acrid and bitter taste, and a strongly alliaceous and fetid smell. It is in part soluble both in water and in alcohol. 7. Scam- [7.] Scammony.—This gum-resin is the hardened juice mony. of the roots of the convolvulus scammonia, a climbing plant of Syria. It has a dark-grey colour, a peculiar and nauseous smell, and an acrid and bitter taste. It forms with water a greenish opaque solution. The greatest part of it is dissolved by alcohol. 8. Opopo- [8.] Opoponax.—This gum-resin is obtained by wounding nax- the roots of the pastinaca opoponax, a native plant ot the countries surrounding the Levant. It is in lumps of a red- dish-yellow colour on the surface, but yvhite within. It has a bitter and acrid taste, and a peculiar smell. About one half of it dissolves in water, with yvhich it forms a milky solution. It is acted upon but feebly by alcohol. 9. Gam- [9.] Gamboge.—This gum-resin is the produce of the hoge. stalagmitis gambogioides, a tree which grows wild in Siam and Ceylon. In Siam, it is obtained by wounding the shoots, but in Ceylon, it exudes from wounds in the bark. It is in the form of yellow cakes, which are opaque and brittle, and break with a vitreous fracture. It has no smell, and very little taste. It forms with water a yellow turbid liquid. It is almost completely soluble in alcohol. 10. Myrrh. [10.] Myrrh___It is not ascertained what plant furnishes myrrh. It is, however, known to grow in Abyssinia and Arabia. It is in the form of tears, of a reddish-yellow colour. It has a peculiar smell, and an aromatic bitter taste. It forms with water a yellow opaque solution. The alcoholic solution becomes opaque upon the addition of water, but no precipitate subsides. CAOUTCHOUC. 511 Chap. I. SECTION IX. OF CAOUTCHOUC. (Commonly called, Indian Rubber.) 1. This peculiar substance first came into notice about Caoutchouc the beginning ot the last century. Some account of it wasis the pro~ sent, in 1736, to the French academy by Condamine, one verai°trees of the academicians, who went to South America to measure of South a degree of the meridian. It is the produce principally ofAmenca' two trees of South America; the hocvea caoutchouc and the jatropha elastica. When these trees are punctured, they yield a milky juice, which, by exposure to the air, lets fall a concrete substance. This substance is caoutchouc. 2. Caoutchouc is a soft and pliable substance, destitute its proper- of taste or smell, and exceedingly elastic and adhesive.ties- When perfectly pure, it is white. In its common state, it has a blackish colour, owing to the manner in which it is dried. This consists in spreading a thin layer of the milky juice over a mould formed of clay, and then exposing it to the action of smoke, which gives it a thin coating of soot. Another layer of the juice is then applied and dried in the same way, and so on for any number of layers, until the coat has the requisite thickness. Caoutchouc is not altered by exposure to the air. It is perfectly insoluble in water, but if boiled for some time in this liquid, it becomes some- what transparent, owing to the abstraction of the sooty matter, and so soft, as that two pieces when pressed together may be welded into one. This property, which it possesses, enables the artist to form tubes of it with facility; for if a slip of it, of uniform thickness, be wound spirally round a glass or metallic rod, so that its edges touch accurately, and then boiled for some time in water, the whole will ag- glutinate so as to form a tube. 3. Caoutchouc is insoluble also in alcohol. Ether, how-it is insoiu- ever, dissolves it, if it be previously subjected to washing; nJjj '^'J6^. yvhich operation seems to act by separating a portion ofiubiein alcohol, and substituting for it a small quantity of water. ether- From this solution, the caoutchouc may be obtained by evaporation unaltered; and hence, by taking advantage of this menstruum, it may be formed into different instru- ments. For common purposes, however, this solvent is too expensive to be employed. It is soluble, without alteration also, in rectified petroleum. In volatile oils it dissolves, but when obtained againrby evaporation from them, it is alter- ed in its properties; being rendered glutinous, and conse- quently unfit for most of the uses to yvhich it is applied, 512 VEGETABLE PROXIMATE CONSTITUENTS Part II. 4. Dr. Thomson has found, contrary to what was formerly BooK H- supposed, that caoutchouc combines with some of the alka- It is soluble line salifiable bases. This chemist accidentally discovered, also in am- w^'le making some experiments, that ammoniacal «as was 3J5 so-1' absorbed when contained in a botUe of this substance. It da*~ was at the same time ascertained, that if the caoutchouc was allowed to absorb successive portions of the gas, it lost its elasticity, and became soft and glutinous. Dr. Thomson afterwards found, that both potash and soda dissolved a small portion of caoutchouc, producing the same changes. 5. Sulphuric acid, after long digestion, chars caoutchouc superficially, but there is no trace of artificial tannin form- ed. When treated with nitric acid, it yields azotic gas, carbonic acid gas, and hydrocyanic acid gas. Hydrochloric acid has no action upon it. > # 6. When exposed to heat, it readily melts; whereby it is changed in its properties, having always afterwards the consistence of tar. When heated sufficiently, it burns with a bright flame emitting a fetid odour. G.nstitu- ?• Caoutchouc is composed of carbon, hydrogen, azote eots of ca- and oxygen, but combined in what proportion is not known. outehoue. FOURTH SET. SUBSTANCES, INSOLUBLE IN WATER, ALCOHOL OR ETHER, AND HAVING A FIBROUS TEXTURE. SECTION I. OF COTTON. ,; h 1. Cotton is the soft down, which envelopes the seeds tained from of various plants, especially several species of gossypium, severalsPe-the us which furnishes the cotton of commerce. Very Xnu. little is known respecting the chemical nature of cotton, but sufficient has been ascertained to demonstrate its pecu- liar nature. , Its proper- 2. Cotton is a substance, composed of very fine hbres, Ji«P P possessing neither taste nor smell. It is somewhat different in its colour, according to the variety of the plant from which it is obtained, but is capable of being rendered of a beautiful white by bleaching. It is completely insoluble in water, alcohol, ether, the oils, and all the vegetable acids. In diluted solutions of potash or of soda, it is in*olume; but these solutions, when concentrated and assisted by heat, dissolve it. It is capable of combining with oxide ot iron, GOTTON—SUBER—MEDULLIN—LIGNIN. £13 and oxide of tin, when dipped into solutions of these me- Chap. I. tals. It combines also with tannin, when immersed in an in- fusion of nut-galls, or other astringent vegetable substance. Hence the use of all these substances in dyeing. 3. Nitric acid, when assisted by heat, converts cotton into oxalic acid. Sulphuric acid developes charcoal. Chlo- rine, if not too much concentrated, bleaches it. SECTION II. OF SUBER. 1. Common cork, the outer bark of the quercus suber, Suber or has been ascertained to possess peculiar chemical proper-®jj[£'r*P*e' ties, and suber is the name by which chemists distinguish it. table sub- 2. Suber is a light, soft, elastic substance, which burnsstancc- with a bright white flame, leaving a black bulky charcoal. When distilled, it yields ammonia. By the action of sul- phuric acid, it is converted into charcoal; and by nitric acid, into suberic acid, a substance resembling wax, artificial tannin, and a kind of starchy matter. SECTION III. OF MEDULLIN. 1. Dr. John gives this name to the pith of the helianthus Meduiiin, annuus (sun-flower), of the cyringa vulgaris, and some fjjj^jj other plants. It is found to be a peculiar substance, pos- pith ofseve. sessing the following properties. ral Plants- 2. It is inodorous and tasteless, and insoluble in water, ether, alcohol, and the oils. It has a peculiar porous struc- ture. It forms oxalic acid, but no suberic acid, by the action of nitric acid. By distillation, it yields ammonia, and the residuum is a charcoal, which has a metallic appearance and some resemblance in colour to bronze. SECTION IV. OF LIGNIN. 1. If the vegetable substance, commonly called wood, belignin; well dried, and then digested first in water, and afterwards ^obuuo- in alcohol, until every thing soluble in these liquids is taken up, what remains will be lignin or woody fibre. n 3T 514 VEGETABLE PROXIMATE CONSTITUENTS Pakt II. 2. It is composed of longitudinal fibres, somewhat trans- ——---parent, and destitute of taste or snull. It is insoluble in tlesPr0per water or m a*cohol. Solutions of potash or of soda, when assisted by heat, decompose it, rendering it soft, and changing its colour to a deep brown. Weak solutions of the same alkaline bases dissolve it, and it may be thrown down from them unaltered by means of an acid. When ex- posed to heat, it blackens without melting or frothing, ex- hales an acrid fume, and leaves a charcoal exactly the shape of the lignin employed. When distilled, it yields an acid liquor, formerly considered peculiar under the name of the pyrolignous acid, but yvhich is ascertained by Fourcroy and Vauquelin to be the acetic acid, combined with empyreu- matic oil. By means of some substance, which Dr. Thom- son considers to be animal charcoal, the empyreumatic oil may be separated, and very good vinegar obtained from this acid liquor. Vinegar is in this way manufactured both in Britain and France. Its compo- 3. According to Gay-Lussac and Thenard, lignin from the oak is composed ot Oxygen 41*78 Carbon 52*53 Hydrogen 5*69 100*00 4. It has been found, that the lignin of all the vegetables yet examined is very nearly the same. When wood is burnt with a smothered flame, a quantity of charcoal is formed, and this is entirely evolved from the lignin. Hence then the quantity of charcoal, which different woods yield, will indi- cate the proportion of their lignin. SECTION V. OF FUNGIN. Fungin, 1. Braconnot has given this name to the substance, how obtain- which remains after the mushroom has been deprived of every thing soluble either in water or alcohol. Its proper- 2. It is a soft, white, insipid substance, possessing but ties- little elasticity. It is insoluble in water, alcohol, ether, and the oils. Solutions of potash or of soda, when diluted, have but little action upon it; but when concentrated and assisted by heat, they dissolve it, so as to form a saponaceous liquid, from yvhich it may be precipitated again by acids. FOREIGN INGREDIENTS'. 515 Chap. I. FIFTH SET. SUBSTANCES, FOUND IN PLANTS, WHICH BELONG RA- THER TO THE MINERAL THAN VEGETABLE KINGDOM. SECTION I. CHLORIDES AS FOREIGN INGREDIENTS. The chlorides which have been found in plants are the Several chlorides of potassium (muriate of potash), of sodium, (com- n^'^'n mon salt), and of magnesium (muriate of magnesia). Chlo- f0„nd iB r.ide of potassium is usually a constituent in vegetable ashes, plants. Chloride of sodium is present in all plants, which vegetate on the sea or near the sea shore. Chloride of magnesium has been detected in some of the fuci, and will not improba- bly be found as a constituent in most marine plants. SECTION II. ACIDS AS FOREIGN INGREDIENTS. The foreign acids found in plants are the sulphuric, ni-L;stoffo. trie, carbonic and phosphoric acids. They are usually com- rdgn acids bined yvith bases in the form of salts. United with lime, p°lant8.m sulphuric acid exists in clover. Nitric acid has been found, combined with potash in the sun-flower, and with soda in barley. Carbonic acid, combined with potash, is found in the ashes of almost all vegetables. Phosphoric acid exists in a free state in the onion; it is present, in union with lime, in all kinds of grain, and combined with potash in barley. SECTION III. SALIFIABLE BASES AS FOREIGN INGREDIENTS. The salifiable bases heretofore found in plants are potash, Sa,inaMe soda, lime, magnesia, alumina, silica, oxidized iron, and base^found oxidized manganese. are, I. Potash is a constituent of almost all vegetables, which L PoUsh- grow at a distance from the sea. Vauquelin has made it pro- bable, that it exists in them combined either with acetic or carbonic acid. It is obtained bv burning plants, which dis- sipates every thing but their alkaline and earthy constitu- ents The residuum is called the ashes, from which the pot- ash may be obtained bv lixiviation; it beiDg soluble while 516 VEGETABLE PROXIMATE CONSTITUENTS PahtII. the other bases are not. It may be obtained from som< ___K"IL plants, without the aid of incineration, as has been lately ascertained by Peschier of Geneva. The plan, which this chemist pursues, is to treat the expressed juice or decoc- tion of any plant yvith magnesia. This salifiable base forms insoluble salts with the acids, whether free or in a state of combination, which usually occur in vegetables. It conse- quently happens, in common cases, that the magnesia sepa- rates all the acids present in these liquids, and falls in the form of an insoluble powder. By this mode of proceeding, Peschier obtained liquids, having all the properties of a so- lution of carbonate of potash. This plan, however, will not succeed, in case the potash exists in the state of nitrate or of sulphate; as neither of these salts are decomposed by magnesia.* The quan- The following table indicates the quantity of ashes and tity of ashes 0f potash, yielded by 100 parts of several plants. and of pot- r J J r »!_««•. ash furnish- _ A8hes- PotMh- ed by seve- Fumitory......21*9 . . . 7*9 raivegeta- Wormwood.....9*7 ... 7*3 bles. ~, Common nettle .... 10*6 . . . 2*5 Beans with their stalks . . — ... 2 Stalks of turkey wheat . . 8*8 . . . 1*75 Oak........1*3 .. . 0*15 Poplar.......1*2 .. . 0*07 Fir........0-34 . . ---- By the above table, it is perceived how small a quantity per cent, different plants yield of ashes and of potash. The fumitory yielded nearly 8 per cent, of potash, while the oak afforded only \\ per cent, of ashes, and one and a half parts only in the 1000 of potash. By the above table also, it is seen, that the quantity of potash, which a plant contains, bears no certain ratio to the ashes which may be formed from it during combustion; and this arises from the circumstance, that the ashes contain variable quantities of other substances. Besides carbonate of potash, (the state in yvhich potash is obtained by incineration from vegetables), there exists usually in them the following compounds; namely, sulphate of potash, sulphate of lime, phosphate of lime, and chloride of potassium. 2. Soda. II. Soda may be obtained from almost all the plants which grow in the sea, or on the sea shore; and it is from different species of the salsola, a genus of plants of this kind, that a large proportion of the soda of commerce is extract- ed. Plants which yield soda, as a general rule, contain a larger proportional quantity of this alkaline base, than other * Annals of Philosophy, xii. 336. FOREIGN INGREDIENTS. 517 vegetables do of potash. Thus the salsola soda furnishes Chap. i. very nearly 20 per cent, of ashes, and nearly 2 per cent, of soda. III. Lime is contained in larger or smaller quantity in 3. Lime. every plant, which has hitherto been examined, except the salsola soda. It has already been stated, that it exists in them frequently combined with sulphuric or phosphoric acid. IV. Magnesia does not exist so generally in vegetables as 4. Magoe- lime. It has been discovered in several sea plants, especiallysia* the fuci. Vauquelin found that the salsola soda contains nearly 18 per cent, of magnesia. V. Alumina has been found in plants in but very small 5. Alumina. quantities. VI. Silica exists in many plants, but particularly in 6. Silica. grasses and equisetums. Sir H. Davy has ascertained, that it forms a part 0$ the outermost bark of these plants. This chemist found, that the epidermis of the bonnet cane yielded 90 per cent, of silica; that of the bamboo 71 per cent.; that of the common reed 48 per cent, and that of the stalks of corn 6J per cent. The concretions sometimes found in the bamboo cane, and called tabasheer, have been ascertained to be composed of silica, sometimes associated with potash. VII. Oxidized iron has been found in considerable quan- 7. Oxidized tities in the ashes of the salsola soda. It has also been de-iron- tected in linen and cotton cloths. It has been discovered in many other vegetable substances. VIII. Oxidized manganese yvas first detected in vegeta- 8. Oxidized bles by Scheele. It has been found by Proust in the ashes raan&ane)*' of the pine, of the vine, the green oak, and the fig-tree. The following table gives the quantity in grains of the six last mentioned salifiable bases (the lime and magnesia in the state of carbonates), contained in thirty-two ounces of the seeds of wheat, of rye, of barley, of oats, and in the same quantity of rye straw, as ascertained by the experi- ments of Schroeder. Substances present. Wheat. Uye. Barley. Oats. Rye Straw. Carbonate of lime. Carbonate of magnesia. Alumina. Silica. Oxidized iron. Oxidized manganese. 12 6 13-4 •6 13-2 2-5 50 134 142 1-4 15.6 •9 3-2 248 25-3 42 66-7 3-8 6-7 33-75 33-9 4-5 144-2 4-5 6-95 46-2 282 3-2 152 2-4 6-8 47-3 48-7 131-5 227-8 238-8 , 518 VEGETABLE ULTIMATE CONSTITUENTS Part II Book II. CHAPTER II. OF THE ULTIMATE CONSTITUENTS OF VEGETABLES. Ultimate The consideration of the proximate constituents of vege- constitu- tables is noyv finished. But these constituents may be refer- en Is of vc*" *j i • • getabies. rea to ctrtain ultimate constituents, or, to speak more cor- rectly, to substances as yet undecompounded. It is the ob- ject of the present chapter to notice them. The folloyving statement gives a view of the yvhole of the ultimate constituents of vegetables, and the states of com- bination in which they occur. SUPPOR- TERS. \: OXYGEN. CHLORINE. 3. IODINE. In various states of combination. CComhincd with Potassium, Sodium ^ and Magnesium, forming chlo- / rides. C Combined with Hydrogen, in the £ form of hydriodic acid. INCOMBL TIBLE i-i 1. AZOTE. r r \ COMBUSTI- B LES. various states of combination! HYDROGEN. 2. CARBON. 3. PHOSPHORUS. 4. SULPHUR. 5. POTASSIUM. G. SODIUM. 7. CALCIUM. 8. MAGNESIUM. 9. ALUMINUM. 10. SILICUM. 11. IRON. 12. MANGANESE. In various states of combination. In various states of combination. Combined with Oxygen, forming phosphoric acid. C Combined with Oxygen, forming 2. sulphuric acid C Combined with Oxygen forming < potash, and with Chlorine form- / ing chloride of potassium. C Combined with Oxygen forming < soda, and with Chlorine forming / chloride of sodium (common salt) C Combined with Oxygen, forming £ lime. Combined with Oxygen forming magnesia, and with Chlorine form- ing chloride of magnesium. Combined with Oxygen, forming alumina. Combined with Oxygen, forming silica. Combined with Oxygen, forming oxidized iron. Combined with Oxygen, forminp oxidized manganese. VEGETABLE ULTIMATE CONSTITUENTS. 519 These ultimate constituents occur in very different quan- Chap, u. tities in plants. The great bulk of them is composed of one The great supporter, oxygen, and two combustibles, hydrogen and car-bulkofve- bon. In some vegetable substances, azote is associated with^mpcTed the three substances already named; and where it is present, of oxygen, it occurs next in amount to them. The remaining ultimate g^ ewrtwn constituents, comprising two supporters and ten combusti- bles, occur in comparatively very small quantities. C 520 J BOOK III. ANIMAL CHEMISTRY. Part II. This portion of the subject will be treated of in five —^—- chapters. Chapter I will embrace the consideration of the chemist constituents of animals, as far as they have been discover- treated of ed by the researches of chemists. Chapter II will have for "\^ye its title the analysis of animal substances, and will give in p rs detail the composition of the organized parts, and the pro- ducts of the human body. In Chapter III, reflections will be entered into upon the chemical constitution of the human body. In Chapter IV, those animal functions which are elucidated by chemistry will be briefly noticed. In Chap- ter V, the chemical changes yvhich take place in animals after death will be described. CHAPTER I. OF ANIMAL CONSTITUENTS. Proximate The proximate constituents of animals may be arranged constitu- under the following heads: ents of ani- mals enu- 1. Gelatin. 9. Saccharine matters. merated. 2. Albumen. 10. Cantharidin. S. Fibrin. 11- Cochenilin. 4. Colouring matter of the blood. 12. Oils. 5. Mucus. 13 Resins. 6. Osmazome. 14. Compound substances, already de- 7. Picromel. scribed in the first part of this work, S. Urea. as animal constituents. All the substances, included in the above enumeration, except cantharidin, cochenilin and the resins, are consti- tuents of the human body. They will be noticed in the or- der in which they have been named, in the following sec- tions. SECTION I. OF GELATIN. Gelatin ex- 1» Gelatin forms an essential constituent in bone, liga- ists in seve-ment, tendon, membrane, and in several other parts of ani- !iub!uKe>. mals» ** exists in Sreat abundance in the hide of the ox, GELATIN. 521 from which it may be extracted by the following process. Chap. I. Take a portion of the hide, and, after having separated the Proccss for hair and other impurities, yvash it with cold water, until extracting this liquid ceases to abstract an. thing. Then boil it in wa- j* froni ^e i • . l j • 1 j j bide of the ter for some time, and evaporate the decoction, until reduced ox. to a small quantity. The concentrated decoction, upon cool- ing, assumes a solid form and a tremulous consistency, and is the same with the animal jelly, used sometimes as food. It is called by chemists gelatin. If the tremulous gelatin be evaporated to dryness by exposure to air, it becomes hard and semitransparent, and breaks with the glassy fracture. In this state, it is called dry gelatin, and is the same sub- stance, which is so frequently employed in the arts under the name of glue. 2. When perfectly pure, gelatin is colourless. It is desti- Properties tute of taste or smell. In the dry form, it does not dissolve °*"gelaun. readily, but swells and forms a soft mass; but in the tremu- lous state, it is completely soluble, if mixed and shaken with water soon after it has gelatinized. It is soluble in hot water, and forms an opal-coloured solution. When made by dissolving one part of gelatin in one hundred parts of hot water, the solution assumes the tremulous form, upon cooling. 3. Dry gelatin undergoes no change by exposure to the Effects of atmosphere; but tremulous gelatin, or gelatin in solution, *eJJ,™D*" very soon undergoes the putrefactive process. When in a dry" state, if it be exposed to heat, it first whitens and curls up like horn, then blackens, and is gradually converted into charcoal. Tremulous gelatin, under similar circumstan- ces, first melts, and afterwards becomes black. 4. When nitric acid is digested upon gelatin, it is partly dissolved, and partly converted into oxalic and malic acids, and an oilv matter which appears on the surface of the liquid. Hydrochloric (muriatic) acid dissolves it readily, and forms a brown-coloured acid solution, which gradually lets fall a white powder. With sulphuric acid, it forms a brown solu- tion, which gradually deepens in colour. 5. Solutions of potash or soda dissolve gelatin readily. The compounds formed do not possess the properties of soap. 6. Gelatin is insoluble in alcohol; and when this liquid is added to a solution of gelatin, the latter becomes milky. When tannin is dropped into a solution of gelatin, it throws Forms, a down a copious white precipitate, consisting of tannin and JJg2l. Kelatin, which forms an elastic adhesive mass. This preci- pitate soon dries in the open air, whereby it becomes con- verted into a brittle, resinous-like substance, insohi n in water capable of resisting the greater number of chemical 3 U 522 ANIMAL CONSTITUENTS Part II. agents, incapable of putrefaction, and possessing, in short, 00K ' L all the properties of overtanned leather. It is on account of this property of tannin, that it is usually employed to detect Tannin ^e presence of gelatin in animal liquids. It must be borne throws in mind, however, that tannin throws down albumen also in rotnas welll^e *orm of a white precipitate; and hence this substance is as gelatin, not a decisive test of gelatin. To prevent all fallacy in as- certaining the presence of gelatin, an animal liquid should be first tested by means of perchloride of mercury (corro- sive sublimate), which will separate albumen, if any be pre- sent. Composi- 7. According to an analysis by Gay-Lussac and Thenard, tion of geia-gelatin is composed of Carbon 47 881 Oxygen 27*207 Hydrogen 7*914 Azote 16*998 100*000 Glue, size 8. Gelatin, with some variety of properties, is used in the and isin- arts under the several names of glue, size and isinglass. different Ta- The uses of glue are very well known. It is manufactured from rieties of the parings of hides, and from the hoofs and ears of horses, gelatin. OXen and other domestic animals, by boiling them in water, and evaporating the solution formed to a proper consistency, Size is a purer kind of glue, manufactured from eel skins, parchment, some kinds of white leather, the skins of horses, cats, rabbits, &c. It is employed in the manufacture of pa- per, and in several other arts. Isinglass is very nearly pure gelatin. It is prepared, almost exclusively in Russia, from the air-bladders of different species of fish of the genus acci- penser. This kind of gelatin is employed in clarifying spi- rituous liquors, in stiffening silk, and for other purposes. SECTION II. OF ALBUMEN. Albumen, 1. The peculiar substance, found in the eggs of fowls, and th*pecuJ,]ar called the white of the egg, is very nearly pure albumen. Sued the" 2. Albumen, when exposed to heat, assumes the solid white of the form, and is said to be coagulated. Coagulated albumen is eg5' very distinct in its properties from uncoagulated albumen, and will be noticed separately. Properties 3. Uncoagulated albumen is a glairy liquid, having very of uncoagu-little taste and no smell. It is readily soluble in yvater; and utedaibu- t^c soiution cnanges vegetable blues to green, in conse- ALBUMEN. 523 quence of the presence of soda. When exposed to the tern- Chap I. perature of 165°, it is converted into coagulated albumen. The same effect is produced by acids or alcohol. When ex- posed to the air for spontaneous evaporation, or to a low heat, it is converted into a brittle, transparent substance, having some resemblance to glass, which may be again dissolved in water, so as to form a glairy liquid as at first. When uncoagulated albumen is diluted with a large quantity of water, for example, ten times its weight, it is no longer coagulable by heat; though acids are still capable of producing its coagulation. When diluted with a still larger quantity of water, even acids lose their coagulating power. The same is the case with dried uncoagulated albumen: when dissolved, in this state, in nine parts of water, it is completely coagulable by heat; but when dissolved in thir- teen parts of water, an imperfect coagulation only takes place by the same means, and the liquid admits of being poured from one vessel to another. 4. During coagulation, albumen neither gains nOr loses {£ "J**1** any principle, nor alters in the least in its specific gravity. h'^t^ot It therefore, becomes a difficult point to ascertain upon yet explain- what its coagulability depends. It is, however, most.proba- «•■ bie, that the coagulating cause gives a new play to chemical affinities, so that the constituents of the albumen assume new states of combination. 5. Uncoagulated albumen, unless dried, very soon un- dergoes putrefaction; and this the more readily, the more it is diluted. Its smell, during putrefaction, is like that ot pus. 6. Dr. Bostock has ascertained, that a saturated solution %£*£** of perchloride of mercury (corrosive sublimate) is a mosta good tesJ delicate test of the presence of albumen. A liquid, contain- for albu- ing not more than „Wth part of its weight of albumen is — rendered sensibly milky by the addition of a drop of this chloride. Tannin also has the property of precipitating al- bumen. It falls, in combination with the albumen, in the form of a very copious yellow precipitate, having the con- sistence of pitch, and which, when dried, becomes brittle and resembles overtanned leather. Tannin, however, is a much less delicate test of albumen than of gelatin. 7. Coagulated albumen is a tough substance haying footed pearl-white colour, and a sweetish, mucilaginous taste. Udet)Bribedi is insoluble in water, and is much less susceptible: ofputre- faction or decomposition than when in the uncoagulated state. When dried at a heat of 212°, it is converted mta hard brittle, yellow substance, semitransparent like horn. From this dried state, it may be brought back to that of newly coagulated albumen, by digestion for several hours in water. 524 ANIMAL CONSTITUENTS. PatitII. 8. Coagulated albumen, by being steeped in diluted nitric Book III ■Hcid lor some time, is converted, as Hatchett has ascert; [Un- converted ed, into a substance, soluble in yvater and possessing the bwhfac-'11 dlstinSuishinK properties of gelatin. tion of ni- 9* Coagulated albumen is readily soluble in a boiling so- tnc acid, lution of potash; ammonia becomes disengaged, and an ani- mal soap is formed. Composi- 10. According to an analysis by Gay-Lussac and The- nard, albumen is composed of Carbon 52*883 Oxygen 23*872 Hydrogen 7'540 Azote 15-7^5 tion of albu men. 100-000 11. It deserves to be mentioned, that, besides these con- stituents, Berzelius considers sulphur, phosphorus, calcium and magnesium to be essential component parts in albumen. Thi first of them, sulphur, is a never-failing attendant upon albumen, wherever it may be found. This circumstance would seem to prove this combustible to be an essential constituent in it; but how far the same is true with regard to phosphorus, calcium, and magnesium remains yet to be satisfactorily shown. SECTION III. OF FIBRIN. Fibrin, how 1« Ir the clot, which forms in blood soon after it is drawn obtained from ;in animal, be put into a linen cloth, and washed re- from blood ,, . , ' ' .. . . , peatedly yvith water, until it ceases to give colour or taste to this liquid, what remains behind will consist of fibrin. This substance was formerly called the fibrous part of the blood. It is found to exist abundantly in the muscular structure of animals, from which it may be obtained by repeated boilings in water. Its proper* 2. Fibrin is a solid substance, having a white colour, Ues* which deepens upon drying, and no taste or smell. When newly extracted from blood, it is soft and elastic, and re- stmbles vegetable gluten. That which is extracted from muscle is brittle, and possesses some degree of transparency. It is not altrred by exposure to air, or speedily so by being kept under water. It is insoluble in cold water. In boiling yvater, it curls up; and, after the boiling has continued for some time, a kind of milky solution is formed, precipi- table by infusion of nut-galls in white flocks, which do not cohere as those produced in a solution of gelatin do. FIBRIN—COLOURING MATTER OF THE BLOOD. 525 3. Both alcohol and ether dissolve fibrin, but not without Chap. I. altering its properties. When it is obtained again by eva- iy1MOiVes in poration from these solutions, it is in the state of a fatty ■■^^•VJjJ mass, having a strong and unpleasant smell. alteration. 4. In solutions ot pure potash or soda, fibrin swells, and becomes transparent and gelatinous. At last a complete so- lution is effected, having a yellow colour with a shade of green. This solution has no analogy to soap, but the fibrin has undergone some alteration in its properties. It is preci- pitated by acids and by alcohol. 5. When exposed to heat, fibrin contracts suddenly, Effects of moves like a piece of horn, and exhales the odour of burn- heat- ing feathers. When the heat is increased to a certain tem- perature, it melts. 6. According to an analysis by Gay-Lussac and Thenard, Compos.- fibrin is composed of Carbon 53360 Oxygen 19*685 Hydrogen 7*021 Azote 19*934 100*000 SECTION IV. OF THE COLOURING MATTER OF THE BLOOD. 1. This peculiar animal substance may be obtained in Colouring the following manner: Mix one part ol the clotot blood, as ^^ completely freed from serum as possible, with four parts ol obtained. sulphuric acid, diluted with eight parts of water. Keep the mixture at the temperature of 158° for five or six hours, and then filter it while hot, washing the residue with tour parts of hot water. Evaporate the liquid, thus obtained, to one-half, and then add ammonia, until the acid is almost, but not completely, saturated. A precipitate appears, which after being washed and dried, is the colouring matter of ^L^ue'nhoeck, by microscopical observations, ascertained Account «c the existence of globules of a red colour, floating in the ry blood; and his statements were confirmed by subsequent ob- servers The red globules were, accordingly, considered to be the colouring matter of the blood but nothing was known of their chemical nature. In 1797, Dr. ^pub- lished a paper, in which he attempted to prove, that the colouring matter of the blood is a peculiar animal sub- tance. This opinion, however, was not acceded to: as it 526 ANIMAL CONSTITUENTS. Pabt II. Book III. Properties of the co- louring matter. Its ashes contain iron. appeared to be proved bv Fourcroy and Vauquelin, that the red colour of the blood was owing to the presence of a subphosphate of iron. This continued to be the prevail- ing opinion, until Brande published his chemical researches on the blood in 1812; in which he proved experimen- tally, that the colouring matter of the blood is a peculiar animal substance. It appears, however, that the results of Brande had been anticipated by Berzelius, in a work pub- lished in 1808 in the Swedish language, but which was not knoyvn in England at the time Brande wrote. 3. The colouring matter of the blood is destitute of taste or smell. When dry, its colour is black. It is not so- luble in cold water, but when suspended in this liquid, it has a wine-red colour. Boiling water produces the same effects upon it, as upon fibrin. It is soluble in all the acids, tried by Vauquelin and Brande. It dissolves in diluted ni- tric acid without any change in colour. Solutions of potash or soda dissolve it and form purple liquids. When exposed to heat, it neither alters its form nor colour; but gives out an animal odour, and yields carbonate of ammonia and a purple oil, the residue being a bulky charcoal. The great bulk of this animal constituent is considered to be composed of some modification of fibrin. When incinerated, it leaves ■g^th of its weight of ashes, which are composed, according to Berzelius, of Oxidized iron 50-0 Subphosphate of iron 7*5 Phosphate of lime with traces of magnesia 6*0 Pure lime 200 Carbonic acid and loss 16*5 100*0 4. Berzelius calculates, that the colouring matter of the blood contains about 3fjj-th of its weight of oxidized iron. This chemist considers, that the substances, indicated in his analysis, do not exist in the colouring matter, but are formed during its incineration. He supposes the radicals only to be present; namely, iron, phosphorus, calcium, and magnesium. SECTION V. OF MUCUS. Animal 1* Animal mucus must not be confounded with the ve- ™r.ff^f" geta^e substance of the same name. The former, however, has several properties in common with the latter. Accord- fers from MUCUS—OSMAZOME—PICROM EL. 527 mgto Dr. Bostock, it may be obtained, by solution and fil- Chap.I. tration, from the white matter, formed by evaporating sa- vegetable liva. This chemist also obtained it, by macerating an oyster mucus. in water, and evaporating the liquid formed. When thus prepared, it has the following properties. 2. It agrees with gum arabic in appearance, taste, solu-Its proper- bihty, and in the property which it possesses of formingties' with water an adhesive solution. After evaporation to dry- ness, it is transparent and inelastic, and resembles gum: it is now insoluble in water, but readily so in all the acids, even when much diluted. It is insoluble in alcohol or ether. It does not coagulate by heat, or gelatinize by evaporation. It is not precipitated by perchloride of mercury (corrosive sublimate), or the infusion of nut-galls; but subacetate of lead occasions a copious white precipitate. SECTION VI. OF OSMAZOME.* 1. This substance may be obtained by the following pro- Osma- cess: Macerate small fragments of beef, in water, for seve- zome, how rai hours, and repeat the maceration several times with fresh ° quantities of water. The liquid, thus obtained, holds, in solution, albumen, the salts of the beef, and osmazome. Se- parate the albumen by coagulating it by heat, and treat the residue, evaporated to the consistence of a syrup, with alco- hol; this liquid takes up the osmazome, and leaves the salts behind. 2. This substance was first pointed out by Rouelle. The name, by which it is here distinguished, was applied to it by Thenard. Dr. Thomson thinks it not improbable, that it is fibrin, somewhat altered in its properties. 3. Osmazome is a brownish-yellow substance, having the its proper- taste and smell of broth. It is soluble both in water and al- *•«• cohol. Its aqueous solution is precipitated by infusion of nut-galls, by nitrate of mercury, and by acetate and nitrate of lead. SECTION VII. OF PICROMEL-f 1. Thenard has given this name to the peculiar sub- Picromei, stance which characterizes bile. It may be obtained by the |^e°b~ * From «rpn smell, and £»,««,- broth, f From T»Xp^ bitter, and ^em honey. 528 ANIMAL CONSTITUENTS. Paht II. following process: Mix fresh bile with sulphuric acid, dilu- UootlIII. ted with three or four times its weight of water. The yel- low precipitate, which thereby appears, must be allowed to subside, and then separated. 'Next heat the mixture gently for some hours, and then decant the liquid part: a green matter will remain, formerly called resin of bile, but at pre- sent ascertained to be a compound of tlu peculiar substance, under notice in the present section, and sulphuric acid. Digest this matter with carbonate of barytes and water. An insoluble sulphate of barytes will be formed; and the picro- mel, liberated from combination, will be found dissolved in the water. It may be obtained trom its aqueous solution by evaporation to dryness. Its proper- 2. Picromel resembles inspissated bile very exactly. It t«es. has a yellowish-green colour, and an intensely bitter taste, which leaves an impression of sweetness. It is soluble in water and alcohol. It dissolves in ether also, but not with- out alteration in its properties. It is not precipitated by the infusion of nut-galls, but is thrown down by nitrate of mer- cury, subacetate of lead, and the salts of oxidized iron. SECTION VIII. OF UREA. Urea, how 1. Urea may be obtained by the following process: obuined. Evaporate any quantity of human urine, by a gentle heat, to the consistence of a syrup, and set it aside to cool: it will be found concreted into a crystalline mass. Pour upon this mass, at several intervals, four times its weight of alcohol, and apply a gentle heat: this menstruum will leave nothing, but some saline substances. Distil the alcoholic solution, thus obtained, in a retort, until it assumes the consistence of syrup; at which time, the whole of the alcohol will have been driven over. The syrupy mass, upon cooling, takes the form of crystals. These crystals consist of urea. 2. This substance was first examined, m 1773, by Kou- elle, iunior, under the name of the saponaceous extract ot urine. In 1799, a full investigation of its nature was made by Fourcroy and Vauquelin, by whom the name urea was Its proper- ^TlJrea is a crystallized substance, usually of a yellowish- «•«• white colour; but, when pure, semitransparent and white. It has a fetid smell, somewhat similar to that of garlic. Its taste is acrid, resembling that of the ammoniacal salts. It is viscid and difficult to cut, and has somewhat the appear- UREA. 529 ance of thick honey. By exposure to air, it attracts mois- Chap. I. ture, and is soon converted into a thick brown liquid. It is very soluble in water, and during its solution a considera- ble degree of cold is produced. It dissolves also readily in alcohol, but not in so large a proportion as in water. The aqueous solution, when left to itsell, gradually putrefies, and the urea appears to be converted into ammonia and acetic acid. When distilled, it exhales a very fetid alliaceous odour, and yields carbonate of ammonia, bihydroguret of carbon, charcoal, benzoic acid, chloride of sodium, and hy- drochlorate of ammonia;* but the three last products are considered by Fourcroy and Vauquelin to be foreign sub- stances. 4. When nitric acid is poured upon crystallized urea, a Action of violent effervescence takes place, large quantities of deu-n,tl,c*fld toxide of azote, carbonic acid, and azote are evolved, and the mixture assumes a dark red colour. After the action is over, there remains, together with some drops of reddish liquid, a white concrete matter, which, when heated, deto- nates like nitrate of ammonia. When, however, nitric acid is dropped into a concentrated solution of urea in water, there immediately fall a number of bright pearl-coloured crystals, which are found to consist of nitric acid and urea. No other acid tried ptoduces this singular effect upon urea. When a solution of urea is mixed with one-fourth of itsofsuiphu- weight of sulphuric acid, no effervescence ensues; but whenrlc acid; heat is applied, there appears, on the surface of the liquid, a quantity of oil, which concretes upon cooling. The other and of by- products of the action of this acid are acetic acid and am-"10™ monia. Hydrochloric acid dissolves urea without alteration. 5. Urea dissolves readily in solutions of potash or of soda, and ammonia becomes evolved. The same evolution is produced by barytes, lime, or even magnesia. The am- monia is derived from hydrochlorate of ammonia, with which urea is constantly mixed. 6. According to an analysis by Dr. Prout, urea is com- Its compo- , r siuon. posed ot Azote 14—one atom. Carbon 6—one atom. Hydrogen 2—two atoms. Oxygen 8—one atom.t 30 • It may be worth while to remark, that the products of the distillation of urea sre a good deal similar to those furnished by uric acid, under like circumstances. f This analysis is taken fiom an abridgment of Or. front's paper on the nroximate principles of the mine. Annals of Philosophy, \\- 3.vi. proximate principles 3 \ 530 ANIMAL CONSTITUENTS. Part II. It consequendy appears, that urea differs from uric acid, Bq»k ill. -m containing an atom less of carbon, and an atom more of hydrogen; and from purpuric acid, in containing an atom less of both carbon and oxygen* SECTION IX. OF SACCHARINE MATTER. Principal Three kinds of saccharine matter of animal origin may anr>uai°sac- ^e numerated; namely, sugar of milk, honey, and the sut charine gar of diabetic urine. These substances will be briefly no- matter are ticed \n the order in which they have been named. 1 Sugar of L Sugar of milk may be obtained by the following pro- n»»lk; cess: Evaporate fresh whey to the consistence of honey, and, after it has concreted into a solid mass by cooling, dissolve it in cold water, and clarify the solution by means of the white of eggs: then filter it, and evaporate it to the consistence of a syrup. This syrup, upon cooling, deposites a number of brilliant white crystals. These crystals consist of the substance in question. Sugar of milk is in the form of semi-transparent crystals, having a whitish colour and a sweetish taste, but no smell. Its specific gravity is 1*5. It is soluble in five times its weight of cold water, and in two and a half times its weight of boiling water. It is insoluble both in alcohol and ether. When exposed to heat, it emits the smell of burning sugar. When distilled, it yields very nearly the same products as sugar. When treated by nitric acid, it is converted into saclactic acid. According to Gay-Lussac and Thenard, it is composed of Oxygen 53*834 Carbon 38*825 Hydrogen 7*341 100*000 3. Honey; II. Honey is, perhaps, rather of vegetable than of ani- and mal origin. It has a yellowish colour, a soft and grained consistence, a saccharine taste, and an aromatic smell. It is converted into oxalic acid by the action of nitric acid. It is very soluble in water, with which it forms a syrup. 3. Sugar of HI* The sugar, which may be extracted from the urine diabetic of persons labouring under diabetes, possesses properties analogous to those of common sugar. When treated with nitric acid, it yields, like common sugar, a portion of oxalic acid. No saclactic acid is formed. SACCHARINE MATTER—CANTHARIDIN—COCHENILIN—OILS. Chap. I. SECTION X. ----- OF CANTHARIDIN. 1. Dr. Thomson gives this name to the substance, disco- Canthari. vered in 1810 by Robiquet, in which the vesicating proper- din*th? ty of cantharides resides. It is obtained from the Spanish JrineTjKrf flies by digesting them, successively, in water, alcohol, and cantharides. sulphuric ether. It is in the form of shining crystalline plates, insoluble in water and in cold alcohol, but soluble in boiling alcohol, which lets it fall upon cooling. It is soluble also in ether and in the oils. When applied to the skin, it acts with great energy as a vesicatory. SECTION XI. OF COCHENILIN. 1. Cocheneal is well known as an insect, which inhabits Coeheniiinj different species of cactus, and is propagated in Mexico *he coiowr- and in some other countries, for the sake of the beautiful cloche-** dye, which it affords. It constitutes the scarlet dye of cloth.neal- Dr. John has succeeded in separating the colouring matter of this insect, to which he has given the name of cochenilin. It has a fine carmine-red colour. It is permanent in a dry air, but becomes glutinous in a moist one. It is soluble in acids, and in pure potash or soda. SECTION XII. OF OILS. 1. Oils are noticed in this place, in order that the enu- Oil enters meration of animal substances may be complete. The rea- WeJy'nt0 der will no doubt recollect, that the oils in general were £1*. treated of pretty fully in a previous part of this work. It would, therefore, be a needless repetition to enter upon their consideration in this place. It may not, however, be without its use to give some account of the animal oil of Dippel. 2. This oil is obtained by distilling the gelatinous and al- buminous parts of animals. The product of the first distil- lation is redistilled, mixed with water; and the oil which first comes over is the animal oil in question. It is a colour- less and transparent liquid, possessing a strong and rather aromatic smell. It is nearly as light, and quite as volatile 532 ANIMAL CONSTITUENTS, PAnTii as ether. It is partially soluble in water. It changes vege- 0 tan*e blues to green, owing, as is supposed, to the presence of ammonia. It dissolves in acids, and forms a kind of im- perfect soap. It yvas formerly held in high estimation as a remedy for fevers, but it is a long time since it has lost its celebrity. SECTION XIII. OF ANIMAL RESINS. Several substances of an animal origin, yvhich partake of the nature of resins, have been classed together under the name of animal resins. The principal of them will be briefly noticed in the following paragraphs. I. Ambergris.—This substance is found floating in the sea, near the coasts of tropical countries, especially of India, Africa, and Brazil. It has been supposed to be of vegetable origin; but it is now generally believed, that it is a concre- tion formed in the stomach and intestines of the physeter macrocephalus, or spermaceti whale. It is a soft substance of an ash-grey colour, with brownish, yellow, and white streaks, and of a specific gravity, varying from 0*78 to 0*92. It has an agreeable smell, and an insipid taste. It is com- posed principally of resin, and a matter with properties in- termediate to those of fat and wax, mixed yvith benzoic acid and charcoal. II. Propolis or Bee-glue.—This is the substance, which bees employ to cover the bottom of a hive, when newly placed in it. It is not altogether certain, that it is an ani- mal substance. It is at first soft and ductile, but, by expo- sure to air, becomes hard. In masses it appears black, but in thin pieces, semi-transparent. It has no taste, but possesses an aromatic odour. It was ascertained by Vau- quelin to be composed principally of resin and wax. III. Civet.—This substance is obtained from the ingui- nal region of the civet cat. It is a yellow substance of the consistence of butter. It is employed as a perfume only, for which purpose it requires that its odour, which is very strong, should be greatly diluted. It has not been analyzed by any chemist; but it may, without impropriety, be classed among the animal resins, until its nature is better known. IV. Castor.—This substance is contained in two bags, a large and a small one, situated in the inguinal regions of the beaver. It is the larger bag on each side, which con- tains the true castor; the smaller one contains a substance resembling it, but much less esteemed. Castor has a yellow Principal animal re- Sins are 1. Amber- gris: 2. Bee- glue: 3. Civet: i. Castor: and RESINS—CHLORTOES—ACIDS—SALIFIABI.E BASES. 533 colour, and, when newly taken from the animal, is nearly Chap. I. liquid. By exposure to air, it hardens, becomes dark-co- loured, and assumes the appearance of a resin. Its taste is acrid and bitter, and its smell strong and aromatic. When used as a medicine, it acts as a stimulating antispasmodic, encreasing the heat of the body in a slight degree only. V. Musk.—This is a secretion, which is deposited in a 5. Musk. kind of bag, situated in the umbilical region of the mos- chus moschiferus, or musk deer, an animal, which inhabits the more elevated regions of Asia, particularly the moun- tains which divide Thibet from China. It has a brownish- red colour, a bitter taste, an intensely strong and aromatic smell, and an unctuous feel. It is partially soluble in water, to which it imparts its odour; and also in alcohol, but this liquid retains none of the odour. It is dissolved, and ren- dered inodorous, by sulphuric or nitric acid. As a medi- cine, it acts as a very powerful stimulating antispasmodic. SECTION XIV. OF COMPOUND SUBSTANCES, DESCRIBED IN THE FIRST PART OF THIS WORK, AS ANIMAL CONSTITUENTS. These substances are either I. Chlorides; II. Acids; Compound ... 0 ,.c li o substances III. Salifiable liases. already I. Chlorides.—In a large proportion of the liquids of the described, human body, and in some of the solids, chloride of sodium c^ut,,. (common salt) is detected upon analysis. Chloride of potas- ™£>e*re sium (muriate of potash) is present also in several animal j1^,^. substances. noes: II. Acids.— There have been discovered, in the analysis 2. Acids: or of the human body, the following acids; namely, the hydro- chloric, sulphuric, carbonic, phosphoric, uric, oxalic, and lactic. The four first named are acids of two constituents; the sixth and seventh are composed of oxygen, hydrogen, and carbon, and the fifth, of the same ingredients, with the addition of azote. The uric and lactic acids are peculiar to animal.matter. Hydrochloric acid is found in urine com- bined with ammonia. Sulphuric acid is a constant ingredi- ent in human urine. Carbonic acid is a constituent in seve- ral parts of the human bodv. Phosphoric acid is the most abundant acid in man, as well as in other animals. Com- bined with lime, it constitutes the basis of bone. It consti- tutes also a component part of almost all the solids and liquids of the body. The uric acid is found exclusively in urine and urinary calculi. Oxalic acid has been found as a 534 ANALYSIS OP ANIMAL SUBSTANCES. Part II. constituent in a species of urinary calculi, to be noticed Book hi. hereafter. Besides these acids, which have been detected in the different parts of the human system, the benzoic acid has been found abundantly in the urine of cows, and the formic, acetic and malic acids have been extracted from the red ant, the first as peculiar to this insect. 3. Salifiable III. Salifiable Bases.—The salifiable bases, found in the constitution of the human body, are ammonia, potash, soda, lime, magnesia, silica, oxidized iron, and oxidized manga- nese. Ammonia exists ready formed in human urine, and is produced abundantly by the putrefaction of animal substan- ces. Potash exists in a few of the liquids of the body. Soda is present in almost all parts of the human structure. Lime exists abundantly in bones, combined with phosphoric acid. Magnesia has been detected in human urine, combined yvith phosphoric acid and ammonia. Silica has been detected in small quantities in hair. Oxidized iron has been found as a constituent of blood, and oxidized manganese as a consti- tuent of hair. CHAPTER II. ANALYSIS OF THE SUBSTANCES COMPOSING THE HUMAN BODY. Animal rob- All the substances, composing the human body, may- be JJlEJider! arranged under the general heads of 1. Organized parts, 2. ed under Products of vital action. But the products of viul action ih Oraa*1*-^ may ^ either natural or healthy, or morbid; and it will be zed parts, convenient to describe them separately, according as they 2'J*ealtny may be the one or the other. Animal substances, therefore, 3. Morbid will be noticed under the following heads: products. I. Organized Parts. II. Healthy Products. III. Morbid Products. J. ORGANIZED PARTS. Organized The substances included under this head are, S.aeI^tednU" 1. Bone. . CMembrane, Tendon, > 7. Brain and Nem meraiea. a. Nail. »• £ Ligament k Cartilage. 5 8. Marrow. 3. Muscle. 6. Gland. 9. Hair. i. Skin. They will be noticed, in the order in which they have been enumerated, in the following sections. BONE. 535 CffAP. II SECTION U ---- OF BONE. 1. The external appearances of bone are too well known to require description. Its internal structure is more or less cellular. Its weight is somewhat various, but is at least twice that of water. Its component parts by chemical analy- Bone eon- sis are chiefly four; namely, an incombt tstible part, fat, gel»" ££imate tin and albumen. consthu- 2. The incombustible part may be (>btained by burning «nt£n in> the bone to whiteness, or by steeping it, for a sufficient time, combustible in a diluted acid. In the first case, the f at, gelatin and albu- part. men are burnt off; in the second, the incombustible part dissolves in the acid liquor, from whicl l it may be thrown down by proper precipitants. 3. The fatty part may be obtained frc >m bone by boiling 2< patty it, reduced to small pieces, in water. Th« s fat will be found matter. swimming on the surface. 4. The gelatin is obtained by boiling tl le bone, for a suf s. Gelatin. ficient time, in water, by which means i t is dissolved. If the solution be sufficiently concentrated, ; as it cools the ge- latin assumes the solid form. It is this < ;onstituent which renders bone fit for the formation of portt tble soup, the ba- sis of which is gelatin. Bone contains abo ut TVth part of its weight of gelatin. 5. When bone is deprived by boiling ot ? its fatty and ge- 4. An aibu- latinous parts, and of its incombustible pe irt by the action j£n«» ^ of a diluted acid; a soft, white, elastic si ibstance remains, cartilage of which has the figure of the original bone, a md which appears bone. to be the same substance, found tipping tl le ends of bones, and called by anatomists cartilage. Cher nically examined, it is found to possess all the properties of coagulated al- bumen. 6. The incombustible part of human b< one, according to Principal n .. 1 r constituent Berzelius, is composed 01 ^the in. Phosphate of lime 81*9 combustible Hydrofluate (fluate) of lime 3*0 gt ofhu- Lime 10 O phosphate Phosphate of magnesia 1*1 of ■»«■ Soda 2*0 Carbonic acid 2*° 1000 7. The substances given in this analy.- lis, together with gelatin, albumen and a portion of fat, wh: ich three constitu- ents form thirty-seven parts in every hundred of fresh bone, make up the proximate constituent ;s of human bone. 536 ANALYSIS OF ORGANIZED PARTS. Part II. They may be all referred to the following ultimate constitu- "0K ni cnts; namely, oxygen, fluorine, azote, hydrogen, carbon, phosphorus, sodium, calcium, and magnesium. Of these, oxygen, carbon, phosphorus and calcium are the principal ingredients. Teeth are 8* Teeth are composed of bone, which is somewhat dif- bone, co ferent from common bone. That portion of them, which a peculiar protrudes beyond the gum, is covered with a peculiar hard substance, matter, denominated enamel. Enamel is destitute of albu- caHedena- mjnous an£j gelatinous parts. When subjected to the action of diluted acids, it is totally dissolved. According to Pepys, one hundred parts of enamel are composed of Phosphate of lime 78 Carbonate of lime 6 Loss and yvater 16 100 Enamel 9* Berzelius has detected about three per cent, of hydro- contain shy-fluate (fluate) of lime in recent teeth, as well as in bone. ^ro^uate o Teeth differ from common bone, in containing more phos- phate of lime and less cartilaginous albumen. Bone of in- 10. The bones of the inferior animals agree in composi- feriorani- tion with those of man. Ox bone yielded to Berzelius, mfcaiiy the uPon analysis, all the constituents of human bone, with the sameashu- additional one, in small proportion, of chloride of sodium man bone. (common salt.) Phosphate of magnesia exists in the bones of inferior animals in larger proportion than in human bone. SECTION II. OF NAIL. Nail is a 1. The human nail is the well known covering of the ends kind of co-0f tne fingers and toeQ This substance has been found by feumen. *" Hatchett to be chiefly -imposed of a membranous substance, which has the properties of coagulated albumen. It appears to contain also a small quantity of phosphate of lime. 2. The horns and hoofs of inferior animals are the same in chemical nature with the human nail; except, indeed, the horn of the buck and hart, which agrees exactly in properties with bone, and which, therefore, may be considered as im- properly denominated horn. Tortoise-shell approaches very nearly to nail in its chemical nature. SECTION III. OF MUSCLE. Muscle de- *• Muscle is the substance, which, in common language, scribed. is called flesh. It is composed of a number of fibres or NAIL—MUSCLE. 537 threads, generally of a reddish colour. It is not easy to se- Chap. II. parate the muscular part, properly so called, from other substances, with which it is mixed. These are a portion of fat, a quantity of blood which pervades its yvhole substance, and cellular membrane which envelopes each fibre. 2. WThen muscle is cut into small pieces and washed re- Analysis of neatedlv with yvater, it is converted into a white, fibrous muscle» r , ' . . . r _, \ _,, how con- substance, having the characteristic properties ot nbrin. 1 he ducted. water, obtained from it, appears as if a portion of blood had been mixed with it; and, when heated, flakes of albumen, combined with the colouring matter of the blood, appear on its surface, and some fibrin precipitates. After being suffi- ciently concentrated, the whole gelatinizes. When in this state, if it be evaporated to dryness and treated yvith alco- hol, a peculiar matter is taken up, while the gelatin and some ammonio-phosphate of soda remain behind. This mat- ter had been considered to be a kind of extractive by Thouvenel; but Berzelius appears to have proved it to con- sist of lactic acid and lactate of soda. If muscle, after being treated with cold yvater, be boiled, it yields an additional portion of the substances already mentioned. 3. Hence it would appear, that muscle is composed of Its constitu- fibrin, to which it owes its form and fibrous texture, united ents- with albumen mixed with the colouring matter of the blood, gelatin, extractive, and ammonio-phosphate of soda. 4. Berzelius gives the following result of an analysis of Itscompo- . ° sition, ae- muscle: cording to I. Solid matters. Berzelius. Fibrin, vessels and nerves 15*8 Cellular matter dissolved by boiling 1*9 17.7 II. Liquid bodies. Chloride of sodium (muriate of soda), "I ^ .g0 and lactate of soda J Albumen and colouring matter of the ") 2#2Q blood J Phosphate of soda 0*90 Extractive 0*15 Albumen, holding in solution phos-1 0.Q8 phate of lime J Water and loss 77*17 82*30 100*00 5. Berzelius's analysis of muscle differs, in many respects, from that deduced from the action of water and alcohol 3 Y 538 ANALYSIS OF ORGANIZED PARTS. PAn-r II. upon the same substance. It agrees with this analysis, ia BoOK lu- giving fibrin, albumen and colouring matter, and phosphate of soda; while the lactate of soda of Bcrzelius's analysis may be taken as equivalent to the extractive of the other. On the other hand, it disagrees in giving chloride of sodi im (muriate of soda), extractive and phosphate of lime as addi- tional constituents, and in omitting gelatin. Muscles of 6. The account, here given, of the chemical constitution animals,dif-0f muscle is to be considered as deduced from the exami- sensible nation of the muscular flesh of the ox. Although the mus- quaiities cular fibres of different animals differ very much in colour, another.6 ant* *n taste when used as articles of food; yet there is no reason to suppose, that they would afford any chemical difr ferences by analysis, unless, indeed, in the proportions of their constituents. It is for these reasons, that the above account of the muscle of the ox will apply with sufficient accuracy to the muscular parts of man. Ultimate 7. From the analysis of Berzelius, just given, it would constitu- appear, that the ultimate constituents of muscle are oxvgen, oj^enu™"!"chlorine, azote, hydrogen, carbon, phosphorus, sodium, and rated. calcium. Of these, oxygen, azote, hydrogen and carbon occur in much the largest proportion. The remaining substances occur in small proportion, and may, perhaps, be considered as accidental constituents. In the above enu- meration, the ultimate constituents of the colouring mat- ter of the blood are excluded, as belonging to a foreign ingredient. SECTION IV. OF THE SKIN. The skin, *• The human skin is composed of three laminae; the composed cuticle or epidermis, the cutis vera or true skin, and a pul- u-mTskin PV lamina between these, called the rete mucosum, or mu- and mucous cous network. network. 2. The cuticle or epidermis is the exterior lamina of the 1. Cuticle, skin, and is that portion of it, which is raised in blisters. It is easily separated from the true skin by maceration in hot water. It is thin and semi-transparent, and possesses a very great degree of elasticity. It is totally insoluble in water or in alcohol, but dissolves in solutions of pure potash or so- da, and of lime; but slowly in solutions of the latter sub- stance. It is not acted upon sensibly by sulphuric or hydro- chloric acid; but nitric acid causes it to lose its elasticity and fall to pieces. This ljtter acid has the property of ting- ing the living cuticle of an indelible yellow colour. The SKIN-MEMBRANE, TENDON, LIGAMENT AND CARTILAGE. 539 same effect is produced upon the dead cuticle by the action Chap.il of this acid, but it requiies a much longer time. The cuticle, when thus tinged, has its colour changed to a deep orange by the action of ammonia. The same cff ct is pro- duce d upon coagulated albumen under similar circumstan- ces. From this fact, and from the effects of reagents upon It «M»b»a cuticle, as above detailed, there is every reason to believe te(, a,j,u_ that this animal substance consists entirely of coagulated al- men. bumen. 3 The true skin is an elastic, dense and strong mem- 2. True brane, composed of a great number of fibres, interwoven in *k.n. an intricate manner. When macerated for several hours in water, the blood and other extraneous substances are re- moved, and the cutis remains, still preserving its fibrous texture. When boiled for a long time in water, it dis- solves completely into a viscous liquid, which, upon evapo- ration, yields gelatin. Hence; it.would appear, thaithe-cu,»«■£ lis of man is composed of gelatin, modified in its nature, so gelatin. as to enable it, by the compactness of its texture, to resist the action of water, except under particular circumstances. th4. The cutis vera constitutes the part of the hide of in- T.^skin ferior animals, which is susceptible of «mye"l°n "£ |£; responds *cr; and it is its gelatinous ™™ "***»£J^&?^ nuroose. The hide is treated with lime, which destroys me rior ani_ cuticle and the hair; and the cutis, which remains, is then mals. steeped in an infusion of oak bark, whereby it combines with tannin, and becomes leather. . 5. The rete mucosum has never been subjected to chemi- .Mucous cal analysis. It is known, however, that it gives rise to the t0 cal analysis. *i occurring n different vane- u.e differ- difference in colour of the skin, °ccurnnS h ence ,f c0. ties of the human race. The true skin, in all nations, is tte |n the same both in colour and in texture; so also is the cu ticL. human On the other hand, the rete mucosumi u,b ack m Ae neptj, yellow or ^""^^JSZ^ Len through in the aborigines of America^an^ b q{ ^^ .^ the transparent cuticle, gives rise to tne y the skin of the human species TheUack c ^ ^ mucosum is destroyed by the action o Beddoes first proved by experiment, on the nnger negro. __^^ SECTION V. OF MEMBRA, TENDON, UGAMENT, AND CART.LAGE. careful analysis; so that a very t>ub complete this section. 540 ANALYSIS OF ORGANIZED PARTS. Part II. Book HI. 1. AL-ro- hrane con- sists of ge- latin. 2. Tendon consists en- tirely of ge- latin. 3. Ligament is modified coagulated albumen, containing a portion of gelatin. Cartilage is coagulated albumen, containing a little gela- tin. I. Membrane is a thin, transparent covering, with which different parts of the body are enveloped. The dura and pia mater, the pleura, peritoneum, and periosteum are all a- amples of membrane. It is susceptible of being tanned and converted into leather. WThen boiled a long time in water, it dissolves almost entirely, and the liquid formed is found to be a solution of glue. When burnt, it leaves scarcely any residuum. There can be no doubt, that membrane consists almost entirely of gelatin. II. Tendons are too well known to require description. In common language, they are called sinews. When boiled a sufficient time with water, thev are completely dissolved, and converted into gelatin. III. Ligament, the substance yvhich binds the bones toge- ther, differs someyvhat in chemical nature from the sub- stances just described. When boiled, it yields a portion of gelatin; but, so far from dissolving entirely, it retains its form and even its strength. It is not unlikely that the part, yvhich is insoluble after long boiling, is coagulated albu- men, somewhat modified. IV. Cartilage differs essentially from both membrane, tendon and ligament. It appears to yield a portion of gela- tin by boiling; but the great mass of it is composed of a substance, insoluble in hot water, and analogous in its na- ture to coagulated albumen. Gland is a ver> hete- rogeneous substance. SECTION VI. OF GLAND. 1. Glands are very complex bodies, made up of several distinct parts. The great mass of them is composed of blood-vessels. These vessels are held together by a kind of cellular texture, which, together with the blood pervading them, and the excretory vessels of those performing secre- tions, may be considered as comprising their yvhole sub- stance. There is very little doubt, that they consist almost entirely of gelatin. Brain de- scribed. SECTION VII. OF BRAIN AND NERVE. 1. Brain is a soft substance, possessing a soapy feel. Its specific gravity exceeds that of water. When kept in close vessels, it has very little tendency to undergo putre- GLAND—BRAIN AND NERVE. 541 faction. Under such circumstances, it has remained a yvhole Chap. II. year without experiencing hardly am change. But when-" exposed to the open air at the temperature of 60°, in a few days it becomes green, exhales a very letid odour, and gives out abundance of ammonia. 2. Cold water does not dissolve brain; but when tritu- rated with this substance, a kind of emulsion is formed, which partly coagulates by heat, or by the action of acids or ot alcohol. The part which coagulates is found to be al- bumen. 3. When brain is triturated with diluted sulphuric acid, Effects of with the exception of its albuminous part, it is totally dis- *"j§1u°^n solved. This solution, by evaporation, deposites crystals of it; sulphate of ammonia; and when this operation is continued to dryness, a black mass is obtained, which is partly soluble in water. The insoluble portion is charcoal; while the so- luble portion is found to consist of the sulphates of ammo- nia and of lime, phosphoric acid, and the phosphates of so- da and of ammonia. The sulphuric acid of the sulphates of ammonia and of lime is derived from the solvent; so that it would appear, that the salts contained in brain are the phosphates of lime, of soda, and of ammonia. Traces of sulphate of lime, however, are detected. All these salts, taken together, do not amount to more than 7o-ffth part of the weight of brain. 4. Nitric acid also dissolves the whole of brain, except and of ni the albuminous part. When the solution is concentrated bytr,cacI ' heat, carbonic acid gas and deutoxide of azote (nitrous gas) are given out, and afterwards a large quantity of ammonia is disengaged. There remains a bulky charcoal, mixed with a quantity of oxalic acid. 5. According to an analysis performed by Vauquelin, 100 its compo- parts of brain are composed ot cording to Water 80-00 Vauquelin. White fatty matter 4*53 Reddish fatty matter 0*70 Albumen 7*00 Osmazome 1*12 Phosphorus, 1'50 Acids, salts and sulphur 5.15 100-00 6. Supposing the salts of Vauquclin's analysis to be the same as those just stated to exist in brain, then the ultimate constituents of this substance would be oxygen, azote, hy- drogen, carbon, phosphorus, sulphur, sodium and calcium. 7. Anatomists have ascertained, that the nerves are com- posed of small fibres, consisting of a substance analogous to 542 ANALYSIS OF ORGANIZED P\RTS. Paht IT. brain, and invested by a membrane, yvhich appears to be de- Boqk III. rjve(i from this organ. Vauquelin has found th'-m to possess Nerves, the same chemical nature as brain. The same is true with the same in regard to the medulla oblongata and medulla spinalis. nature as brain. i ■= SECTION VIII. OF MARROW. Marrow of 1. In the cavities of the long bones, there is found a pe- tnff'0*' J101 cu^ ir substance of a fatty nature, yvhich is denominated fromhu- marrow. Berzelius has examined, in detail, the chemical man mar- properties of this substance, as it exists in the t ugh bone of the ox. As it is not probable, that the marroyv of human bones differs essentially from ox marroyv, it may not be without its use to give the result of this examination. Its analysis, 2. Cold water, when digested upon ox marrow, takes up duct d"1 aDout To-o-tn Part ot tn*s substance, which is ascertained to consist of coagulated albumen mixed yvith phosphate of lime and of iron, gelatin, and the peculiar extractive of Thouvenel. Boiling yvater causes it to melt and swim on its surface, and dissolves a part of it, which is found to con- sist chiefly of extractive, gelatin, and a peculiar matter, ap- proaching, in properties, to coagulated albumen. 3. If marroyv, after having been thus subjected to the ac- tion of hot and cold water, be melted and passed through a cloth, a portion remains on the cloth consisting of blood- vessels &c. It may noyv be considered as being in a state of purity. Pure mar- 4. Pure marrow, thus obtained, is a soft substance, having row descri- a bluish-white colour, a*ad rather sweetish taste. It melts bed' when heated to the temperature of 113°. When distilled, it yields a liquid and a solid oil, water, carbonic acid gas and bihydroguret of carbon, and there remains a dark broyvn and brilliant charry matter, amounting to £Tth part of the marrow employed. 5. Berzelius states the constituents of 100 parts of ox marrow as follows: Pure marrow 96 Skins and blood-vessels 1 Albumen Gelatin Extractive Peculiar matter Water 100 MARROW—HAIR. 548 6. From this statement, it appears, that marrow, as it is Cbap. II. found in bone, is composed almost entirely of a peculiar fixed oil, to which Berzelius gives the name of pure mar- row. All the component parts of marrow, exclusive of the phosphates of lime and of iron, may be referred to oxygen, azote, hydrogen or carbon as ultimate constituents. SECTION IX. OF HAIR. 1. Vauojjelin has published a minute analysis of human Analysis of hair. By means of a Papin's digester, this chemist was en- ^nrjahc°^, abled to dissolve this animal substance, which, at the boiling by Vauqae- temperature, is insoluble in water. The solution contains a hn* kind of oil, which may be separated by the filter. 2. The filtered solution, when treated with an infusion of nut-galls, lets fall a copious precipitate, which Vauquelin considers to be inspissated mucus, but which is considered by Hatchett, with more probability, as some modification of coagulated albumen. When silver is exposed to its action, it is blackened, yvhich indicates the presence of sulphur. When very much concentrated by evaporation, it does not gelatinize. This would appear to show the absence of gela- tin, but Achard and Hatchett have proved by experiment, that hair contains a portion of gelatin, to which it oyves its suppleness and toughness. 3. When alcohol is digested upon black hair, it separates from it two kinds of oil; one of which falls in the form of white shining scales, as the alcohol cools, while the other, which is greyish-green, is obtained by evaporation. 4. When hair is incinerated, the ashes amount to not more than \\ parts in the 100. Vauquelin found these ashes to be composed of iron and manganese, phosphate, sulphate and carbonate of lime, chloride of sodium (muriate of soda), and a considerable quantity of silica. 'I he ashes of red or white hair contain less iron and manganese than those ol* tained from other varieties; but thev have magnesia as an ingredient, not found in the ashes of hair of other colours. 5 From these various data, furnished by the researches of Vauquelin and Hatchett, it would appear, that human hair is composed of the following substances: Coagulated albumen, somewhat modified. Iuconstitu- Sulphur. G.latin. Two kinds of oil. 544 ANALYSIS OF HEALTHY PRODUCTS. enumera ted Iron and manganese. Phosphate, sulphate, and carbonate of lime. Chloride of sodium (muriate of soda.) Silica. 6. From the above statement it follows, that the ultimate constituents of hair are oxygen, chlorine, azote, hydrogen, carbon, phosphorus, sulphur, sodium, calcium, silicum, iron, and manganese. II. HEALTHY PRODUCTS. Healthy The healthy products of the vital action of the human products body are nearly all secretions. They will be arranged as fol- lows: a. Products of the digestive function.—These are Chyle, Blood, and Feces. All the remaining healthv products are secretions, and will be called by that name in giving the remaining groups of the arrangement. b. Secretions subservient to the digestive function.—These are Saliva, Gastric Secretion, Pancreatic Secretion, and Bile. c. Secretions subservient to the organs of sense.— These are Tears, Mucus of the nose, and Cerumen of the ear. d. Secretions contained in circumscribed cavities. —These are Humours of the eye, Liquor of the pericardium, and Sinovia. e. Secretions of an excrementitious nature.—These are Urine, and Sweat. f. Secretions dependent upon sexual organization.—These are Semen, Milk, and Liquor of the amnios. The healthy products will be noticed, in the order in yvhich they have been named, in the following sections. o a. Products of the Digestive Function. The products of the digestive function are Chyle, Blood, and Feces. SECTION I. OF CHYLE. Chyle is ta- 1. Chyle is the liquid taken up from the food in the in- ken up testines, after the latter has undergone certain changes in the CHYLE. 545 stomach. Alimentary matter, thus fitted to yield chyle, is call- Ca**- IL ed chy me; and the vessels, which separate the chy le from it, from the are called lacteals. These vessels unite together and form »•">'• • ■' T one trunk, called the thoracic duct, yvhich communicates d^char^d with the blood-vtssels. Chyle is, therefore, a product of into the digestion, yvhich passes into the blood, in order to supply g^"1"™" the waste, which this important liquid is constantly suffering in the circulation. 2. It is only within a few years, that the chemical nature of chyle has been investigated. The ch.le of the horse was examined experimentally, in 1811, by Emmert, and, in 1812, bv Vauquelin; in yvhich year also, Brande examined the nature of this iiquid. In 1815, Marcet made a comparative examination of the chyle of animals, according as they live upon vegetable or animal food. 3. Chyle, examined from the thoracic duct about five Chyle de- hours after food has been taken, is a white, opaque, liquid,scn e{ • yvithout smell, and having a slightly acid taste, mixed with a perceptible sweetness. In about ten minutes after it is drawn, it coagulates into a stiff jelly. After remaining tyven- It coagu- ty-four houis, it separates into two distinct parts; a firm, contracted coaguium, and a colourless liquid. 4. Vauquelin considers the coaguium, as a substance in- itscoagu- termediate, in properties, bet* een albumen and fibrin. He Jj^J^ considers it in the course of conversion from albumen to tween aibu- fibrin. It is not so fibrous, in its texture, as fibrin, or so{»enandn- easily acted upon by solutions of pure potash or of soda. When burnt, it leaves a charcoal, yvhich is found to contain chloride of sodium (common salt), phosphate of lime, and traces of iron. 5. The liquid part of chyle becomes coagulated by heat, Its liquid *r i r • 11 p«*Pt COD- bv alcohol and acids; hence, therefore, it contains albumen. taingalbu. After the albumen is separated, if the remaining liquid be ■»«» ™* evaporated to one-half, in a heat not exceeding 200°, on cool- £g£° ing, it deposites crystals, which Brande considers to be sugar of milk. 6. From the foregoing statement, there may be deduced the folloyving constituents of chyle: Water A substance intermediate in nature betyveen albumen and fibrin, Albumen, Sugar of milk, Phosphate of lime* Chloride of sodium, 7 These substances may be referred to the following ul- 3 Z 546 ANALYSIS OF HEALTHY PRODUCTS. HARTm timate const,tuents; namely, oxygen, chlorine, azote, hy- Jl----1 drogea, carbon, phosphorus, sodium, calcium and iron. 8. The chemical account of chyle, here given, can be con- sidered as applying to the chyle of the horse only. There can be very little doubt, however, that the chyle of man is the same in constituents, varying somewhat in the propor- tions in yvhich they combine. SECTION II. OF BLOOD. Blood de- 1. It can hardly be necessary to describe the general ap» scribed. pearances of blood. In the more perfect animals, as in man for example, it has a red colour, an unctuous feel, a slightly saline taste, and a peculiar smell. The mean specific gravity of human blood is 1*0527. It separates 2. Blood, soon after it is drawn, coagulates into a solid ousi'^nto mass* wn*cn slowly separates into two parts; a liquid part, two parts, which is called serum, and a solid part, forming, as it were, called se- an island in the former, yvhich is called crassamentum. crtssamen- The crassamentum generally constitutes about one-fourth tum. of the blood; but its quantity is not uniform. In some rare cases, it is said to compose one-half, and in others only one- fifth of the mass of the blood. The cause of the spontaneous decomposition of blood is not satisfactorily known. It takes place equally in close or in open vessels, or whether it be allowed to cool, or is preserved at the animal heat. l.Serum 3. Serum is a light, greenish-yellow liquid, having the described. taste, smell and feel of blood, but much less consistency. Its mean specific gravity is 1*0287. It changes some vegetable blues to green, owing to the presence of soda. When heated to the temperature of 156Q, or when mixed with boiling wa- ter, it coagul ites, and the coaguium proves to be albumen. The coagulation, however, is prevented, if it be mixed with six times its weight of cold water. If the coaguium be cut into small pieces and squeezed, a liquid is forced out, which is called serosity. Besides albumen, serum contains a large proportion of water, holding in solution soda, lactate of soda, chlorides of sodium and of potassium (muriates of soda and of potash), and some animal matter. Its compo- 4. Berzelius found the constituents, just enumerated, mi'-dhiRto comb*n«"d in the following proportions in the serum of hu- Berzelius; man blood: BLOOD. 547 Water 905*0 Chap.II. Albumen 80*0 Chlorides of potassium and of sodium (muriates of potash and of soda) Lactate of soda yvith animal matter 4.0 Soda, phosphate of soda yvith animal matter 4*1 Loss 0*9 } 6.0 1000*0 5. Dr. Marcet found human serum composed as fol- according lows: t0 Ml4lcet Water 900*00 Albumen 86*80 Chlorides of potassium and of sodium ") (muriates of potash and ot soda) J Muco-extractive matter 4.00 Subcarbonate of soda 1 '65 Sulphate of potash 0*35 Earthy phosphates [of lime and magnesia] 0*60 1000*00 6. Dr. Marcet's analysis agrees very nearly with that of Berzeiiurs Berzelius in the three first items. Dr. Thomson considers jj™!^^', the muco-extractive matter of Dr. Marcet to be equivalent ^8 ^pj" to the lactate of soda with animal matter of Berzelius's ana- ed. lysis. Berzelius detected, in serum, phosphate of soda, which does not appear in Dr. Marcet's analysis. The soda in the first analysis was no doubt in the state of subcarbo- nate, as stated in the second. The substances, stated in the two last items of Dr. Marcet's analysis, occur in exceed- ingly minute proportion. Their constituents, except the pot- ash, are considered by BerMius to be formed during in- cineration; their radicals, namely, sulphur, phosphorus, cal- cium and magnesium, being supposed by this chemist to be component parts of albumen. 7. The crassamentum of the blood has a red colour, and 2. Crassa- considerable consistency. Its mean specific gravity is about J^,™ 1*245. When washed with water as long as this liquid ab- stracts any thing, a white elastic solid substance remains, which is found to possess all the properties of fibrin. The portion, which is carried off by the water, is the colouring matter of the blood. Besides these ingredients, there exists in the crassamentum a portion of albumen. 8. From these statements, it appears, that the whole of Constitu- the constituents of blood arc the folloyving: "J^ Serum—composed of Water. Albumen. 548 ANALYSIS OF HEALTHY PRODUCTS. Paut II. Chlorides of potassium and of sodium. 00K llt- Lactate of soda yvith animal matter. Soda, phosphate of soda yvith animal matter. Crassamentum—composed of Colouring matter of the blood. Fibrin. Albumen. 9. All these substances may be referred to the following ultimate constituents; namely, oxygen, chlorine, azote, hy- drogen, carbon, phosphorus, sulphur, potassium, sodium, calcium, magnesium and iron. Blood is dif- 10. Very little has been done, in ascertaining the compa- dlfie'r-ent rative nature of blood, in different animals, at different ages animals. of the same animal, and as altered by disease. Kouelle ex- amined the blood of a number of animals, and found the same constituents in all, though united in different pro- portions. Fourcroy has examined the blood of the human foetus, and found it to differ from adult blood in the follow- ing particulars. It contained a larger proportion ol colouring matter and of a darker colour. Albumen was present in it, but no fibrin or phosphoric acid. Diseased 11. The blood of persons, labouring under different c£ai}feXof diseases, has been examined by Deyeux and Parnruntier. That peculiar appearance, yvhich blood usually exhibits during inflammation, called the buffy coat, is found to be formed, in consequence of the subsidence of the colouring matter of the blood from the crassamentum, thereby leaving its fibrin, unmixed on the surface. This appearance of blood seems to depend upon the slowness yvith which it coagulates, or its want of viscidity. The blood, drawn from patients labouring under scurvy, was nor found to differ from healthy blood, except in not being so easily coagulated. The serum of the blood of diabetic patients frequently puts on the ap- pearance of whey. It has been ascertained, that blood, when drayvn in this disease, contains no perceptible quantity of sugar. SECTION III. OF FECES. The suite 1. After the food has undergone certain changes in the inCthenfoodstomacn ^y l^e act'on °f the gastric secretion, it passes into explained, the duodenum, where it undergoes f irther changes by being which re- niixed with the bile and pancreatic secretion. After experi- sults in the . . . . .' _ , _. . , , , , ' . formation encing these changes, it is fitted to afford chyle by the action of chyle of the lacteals; and accordingly these vessels separate this FECES. 549 milky fluid from the alimentary mass, especially in the small Chap.ii. intestines, as it passts along the alimentary canal. The ~" whole of the alimentary mass, however, is not fit for con- version into chyle; but a refuse part, unfit for the purposes of nutrition, is propelled successively through the whole length of the tube, and is ultimately discharged per anum. This refuse part constitutes the feces. 2. In order to elucidate the process of digestion, Berze- Analysis of lius, in 1806, undertook the disgusting task of analyzing S^ed human feces. The result of this chemist's researches will be by Berxe- given in the present section. hus" 3. Feces are supposed to derive their colour from admix- ture of bile, which, being present in different proportions, causes their variety in this respect. Their odour is fetid and peculiar, and changes gradually to sourish. Their taste is sweetish-bitter. 4. The proportion of aqueous parts in feces is variable. As a medium, it may be considered that they lose about three- fourths of their weight in drying. 5. "When feces are diffused through water by maceration and agitation, and the liquid, thus formed, strained through a linen clcth, there is obtained upon it about seven per cent. of a greyish-brown matter, which, upon being dried, proves to be the remains of animal and vegetable substances used as food. The strained liquid, upon standing, deposites a yel- lowish-green slimv matter, amounting to fourteen per cent. ot the feces examined, which is found to be composed of three distinct substances: 1. A fatty matter, resembling picromel, taken up by alcohol; 2. A peculiar yellow-colour- ed substance, which may be separated by water; and, 3. A greenish-grey substance, neither soluble in water nor alcohol, which leaves, when incinerated, some silica and phosphate of potash. After this slimy matter is separated, the liquid which remains is at first of a light yellow colour, but after- wards, by exposure to the air, becomes brown, and at last muddy. When concentrated by evaporation, crystals of am- monio-phosphate of magnesia make their appearance. Besides this triple salt, the liquid is found to contain, 1. Albumen, amounting nearly to one per cent. 2. About the same pro- portion of a mixture of picromel and soda, which Berzelius considers as bile. 3. A peculiar reddish-brown substance soluble both in water and alcohol, and precipitable by a small portion of tannin in the form of a red powder, in the amount of 2*7 per cent. 4. Various salts; namely, carbonate and sulphate of soda, and phosphate of lime, together with chloride of sodium (common salt). These substances, in- cluding the ammonio-phosphate of magnesia, constitute 1*2 per cent, of feces. 550 ANALYSIS OF HEALTHY PRODITTS. Part II. 6. The following statement gives the pi< aue result of the Bo0K ni analysis of 100 parts of feces, as conducted by Berzelius. Result of Water 73*3 Berzeiius's Vegetable and animal remains 7*0 analysis. _. ° . ohmy matter; consisting of altered picromel, a peculiar yellow solubli substance, and agreen- ish-grey insoluble substance 14*0 Albumen *9 A mixture of picromel and soda *9 A peculiar reddish-broyvn substance 2*7 Salts, &c. 1*2 1000 The an- 7. The above analysis cannot be considered as very satis- salu'factory ^actory. The chemist is presented wiih three substances, yvhich have not been identified with any known forms of matter, and yet probably are not peculiar in themselves. These substances, including the altered picromel, amount to more than three-fourths of the feces, exclusive of the aqueous part and the animal and vegetable remains. Con- sequently, they compose the great bulk of this animal sub- stance, and must be considered as its most characteristic part. It yvould be important to have the peculiar nature of these substances satisfactorily ascertained, or, otherwise, their identity with knoyvn forms of matter manifested. It certainly would be an object of curious inquiry to investi- gate the peculiarities in the constituents or manner of combi- nation of matter, which render it unfit to be absorbed by the lacteals. Will any particular ultimate constituent be found redundant in such matter? This question deserves to be satisfactorily answered. b. Secretions subservient to the Digestive Function. These secretions are Saliva, Gastric Secretion, Pancreatic Secretion and Bile. SECTION IV. OF SALIVA. Saiivadei- *• Saliva is a limpid and somewhat viscid liquid, des- cribed, titute of taste or smell. Its specific gravity is very little greater than that of water. It does not mix readily with water, but by trituration in a mortar, the union may be ef- fected. It is said to absorb oxygen readily from air. When triturated with several of the metals, as gold, silver, or mer- cury, it is known to cause their oxidizement. When evapo- SALIVA—GASTRIC SECRETION. 551 rated, it swells exceedingly and leaves a brown-coloured Chap, n. crust. When dis illed, it yields water, a little carbonate ol ammonia, some oii, and an acid. 2. According to an analysis by Berzelius, 1000 parts of Its eompo- saliva are composed of slt,on' "Water 992*9 Peculiar animal matter 2*9 Mucus 1 4 Chlorides of potassium and of sodium 1 } (muriates of potash and of soda) Lactate of soda, and animal matter 0-9 Pure soda 0*2 1000*0 3. In the above analysis, the peculiar animal matter pos- sesses the properties ol mucus, as heretofore detailed; while the mucus of Berzelius bears a close analogy to coagulated albumen. 4. The peculiar substance, in common language called tartar, which adheres to the teeth, was found by Berzelius to be composed principally of the phosphates of lime and of magnesia. • SECTION V. OF THE GASTRIC SECRETION. 1. Very little is knoyvn at present of the exact chemical Gastric s»- nature of the gastric secretion. The accounts of different ^Jjj."'^ physiologists, who have examined it, are so discordant, that ^perfectly no precise notion of its composition, in the healthy state, ^certain- can be formed from them. This discordancy, without doubt, is to be attributed, in part to the difficulty of obtaining this secretion pure, it being always mixed with the remains of food and often yvith bile; but principally to its natural varia- tions, depending upon the nature of the food, the peculiar constitution of the animal, and upon the longer or shorter time after a meal, at which it is examined. 2. Several methods have been employed by physiologists Different for obtaining the gastric secretion pure. One method is to "^dngft kill an animal, after it has fasted tor a considerable time. fr„m the and to take the secretion from the stomach. Another me- stomach. thod is to force animals to swallow tubes, perforated with holes and containing drv sponge, and afterwards to return them by vomiting. In this way, Spallanzani obtained a liquor from the stomach of rrows. which he considered to be the gas- tric juice. No dependence, however, can be placed upon any 552 ANALYSIS OF HEALTHY PRODUCTS. Pakt ii. method for obtaining this secretion, of which vomiting makes Bo0K in- a part; since in all cases, where the stomach is nearly empty, vomiting produces a discharge of bile. A third method, for obtaining the secretion, is to excite vomiting in the morn- ing before taking food. This method, Spallanzani and Gossc practiced on themselves. Its proper- 3. Spallanzani found, that the liquid, yvhich he threyv up ties.accord- \n the morning, and yvhich he considers to be the gastric se- mg to Spal- . . °T i.i-i • . ° lanzani. cretion in a pure state, had a saltish taste, yvithout any mixture of bitterness. When first ejected, it yvas frothy and somewhat glutinous. Upon standing, it deposited a scanty sediment, and became as limpid as water. It had no tendency to pu- trefaction; for when kept in a stopped vial, for longer than a month, exposed to the heat of an Italian summer, it un- derwent no perceptible change. Properties 4. According to the observations of Brugnatelli, the gas- tric'secre- tr'c stcretion of carnivorous animals has an acid and resi- tion of infe-nous odour and a bitter taste, is not at all watery, and nor am- consists of an uncombined acid, a resin, an animal substance, and a small portion of common salt. According to Spallan- zani, who seems to have settled the point by experiment, the secretion in these animals, including rftan, is neither acid nor alkaline in its natural state; and becomes acid only by the use of vegetable food in large proportion, which proper- ty it derives from such aliment in its tendency to undergo the acetous fermentation. Again, Brugnatelli asserts, that the gastric secretion of herbivorous animals has a bitter, saltish taste, and contains ammonia, an animal extract, a pretty large proportion of common salt, and a large quantity of water. The gastric secretion of oxen and calves has been proved by Macquart and Vauquelin to contain, invariably, uncombined phosphoric acid. Experi- 5. It is much to be desired, that an elaborate analysis of jn*ntal,n" the gastric secretion of man and other animals should be xerydesira-performed by some chemist well fitted for the task. It is blh°n l!lf not exPectcd, that any light yvould be thrown upon the func- thVgastric t'on °f digestion by this research; for it would seem, that secretion, this operation has some hidden connection with vitality, with which chemistry can have no concern. This good, however, might fairly be expected to result from the inves- tigation: it would illustrate the difficult disease of dyspepsia, by pointing out the chemical peculiarities of the secretion in particular cases, and thereby suggesting the appropriate remedies. It would also be productive of important advan- tages, by ascertaining in yvhat cases of derangement in the digestive organs, the gastric secretion of particular animals would be serviceable as a remedv. PANCREATIC SECRETION—BILE. 553 6. On the subject of the gastric secretion as a remedy, it Chap.ii. may be proper to remark, that this liquid, derived from JT ~~" • • . ... * ine gastric graminivorous animals, has been successfully employed as secretion as an external application to ill conditioned ulcers, especially a iemedJ- such as have a sloughing tendency, and are attended with great pain. The ulcer is bathed with the liquor, and then dressed with lint moistened with it. It is considered to act as a stimulating antiseptic. By its stimulus, it substitutes a healthy for a diseased action, and by its antiseptic qualities, it destroys the foetor, which is an invariable attendant upon such ulcers. In some cases of indigestion, attended by vomit- ings of acid and black matter, and when the gastric secre- tion has lost its energy, the internal exhibition of the gas- tric liquor from ruminating animals, has been found by Carminati to be of great use. The dose employed was one ounce of the fresh secretion. This same philosopher yvas enabled to cure intermittents by the use of the liquor; in which cases, he increased the dose to three ounces a day. SECTION VI. OF THE PANCREATIC SECRETION. 1. Nothing is knoyvn as to the chemical nature of this Pancreatic secretion. There is Rood reason, however, to believe, that it secretion , ° ,. ' ' ' supposed to is very similar to the saliva. resemble saliva. SECTION VII. OF BILE. 1. Human bile is a liquid, generally viscid, of a some-Human bile what bitter taste. Its colour is variable, being sometimes described. green, sometimes yellowish, and occasionally nearly colour- less. It usually contains a yelloyv matter, suspended in it. When evaporated to dryness, the xesidue is a broyvn mass, amounting to about ^th of the weight of the bile experi- mented upon. 2. According to an analysis by Berzelius, 1000 parts of Its com in- human bile are composed of Water 908*4 Picromel 80*0 Albumen 3*° Soda 4*J Phosphate of lime 0*1 Chloride of sodium (common salt) 3*4 Phosphate of soda with some lime 1*0 1000*0 4 A 554 ANALYSIS OF HEALTHY PRODUCTS. PAnT ii. 3. Bv an analysis of ox bile performed bv Thenard, it ap- Book in. j. . . y. . . __pears, that this liquid contains all the ingredients of human .-------^-----~, ----- -----—j— wv».»»...,.„ — -— —pj.--------- Ox bile and bile, as ascertained by Berzilius, t x. cpt albumen; and the compared, additional ingredients of resin, which may be considered as included under the title of picromel in Berzelius's analysis, yellow matter, yvhich is probably equivalent to the albumen of the human bile, sulphate of soda, and oxidized iron. So that the real difference, between the bile of man and of the px, consists in the presence of sulphuric acid and oxidized iron in the latter, not to be found in the former. Thenard examined the bile of the calf, the dog, the sheep, and the cat, and found it to resemble ox bile exactly in proper- ties and constituents. On the other hand, the bile of the soyv was found to differ entirely from that of the animals just mentioned; for it does not contain albumen, animal matter, or picromel. Ultimate 4. The substances, enumerated in Berzelius's analysis of constitu- human bile, may be all referred to the following ultimate ents ot bile. . J , , , Y , „ constituents; namely, oxygen, chlorine, azote, hydrogen, carbon, phosphorus, sodium, and calcium. c. Secretions subservient to the Organs of Sense. These secretions are Tears, the Mucus of the Nose, and the Cerumen of the Ear. SECTION VIII. OF TEARS. 1. The tears are a transparent colourless liquid, having scarcely any smell, but a perceptibly saltish taste. Their spe- cific gravity is somewhai greater than that of distilled wa- ter. They change some vegetable blues to a green; which property they possess in consequence of the presence of Analysis of uncombined soda. When exposed to the air, the aqueous tears, how portion gradually evaporates, and the residue assumes some conducted. consistency# When brought nearly to a state of dryness, cubic crystals of chloride of sodium (common salt), combi- ned with a portion of soda, make their appearance. When evaporated completely to dryness, they lose 96 per cent, of water, and the residue is a yellow matter, having the pro- perties of inspissated mucus. This mucus is insoluble in water, which is supposed to be owing to the absorption of oxygen. When it is burnt in the open air, the residuum TEARS—MUCUS OF THE NOSE—CERUMEN. 555 contains traces of phosphate of lime and phosphate of soda. Chap, il Tlv.se salts, together with the uncombined soda and the chloride of sodium, amount to about one per cent, in the constitution of tears. 2. From these data, it may be stated, that 100 parts of tears are composed of Water 96 Mucus 3 Chloride of sodium, soda, phos- phates of lime and of soda } 100 3. These substances may be all referred to one or other of the following ultimate constituents; namely, oxygen, chlorine, hydrogen, carbon, phosphorus, sodium and cal- cium. SECTION IX. OF THE MUCUS OF THE NOSE. 1. Berzelius gives the following analysis of the mucus of Mucus of the nose. the n09e- Water 933*7 Mucus 53*3 Chlorides of potassium and of sodium 1 fi (muriates of potash and of soda) J Lactate of soda with animal matter 3*0 Soda 0*9 Albumen, and animal matter soluble in water ") but insoluble in alcohol, with a trace of phos- > 3*5 phate of soda J 1000*0 SECTION X. OF THE CERUMEN OF THE BAR. 1. Cerumen is that orange-yellow substance, commonly Cerumen of called ear wax, which is found in the auditory canal. It is j.h* e*£ d secreted by glands situated on this canal, and is at first li- quid, but becomes gradually concreted by the action of the air. Its taste is bitter. When heated on paper, it leaves an oily stain, and emits a slightly aromatic odour. 2. Fourcroy and Vauquelin consider cerumen as compo- Itsconstitu- sed of the folloyving ingredients; 1. albumen, 2. an inspissa- ents" ted oil, 3. a colouring matter, 4. soda, 5. phosphate of lime. 556 ANALYSIS OF HEALTHY PRODUCTS. PAnT n. Book III. d. Secretions contained in Circumscribed Cavities. These secretions are Humours of the Eye, Liquor of the Pericardium, and Sinovia. Humours of the eye are the a- queous and vitreous hu- mours, and the crystal- line lens. Composi- tion of the different humours. SECTION XI. OF THE HUMOURS OF THE EYE. 1. Anatomists describe three distinct transparent sub- stances as filling up the internal cavity of the eye, under the names of the nqueous and vitreous humours, and the crys- talline lens. These substances have been examined chemi- cally by Chenevix and Berzelius. 2. The experiments have been made chiefly on the eyes of sheep; so that the analyses, which will be given in this section, are to be considered as of the eye of this animal. But as there is no perceptible chemical difference between the humours of the human eye, and of the sheep's eye, what- ever may be said of the humours of the latter may be con- sidered applicable to those of the former. 3. Berzelius found that 100 parts of the aqueous humour are composed of Water 98-10 Albumen trace. Muriates [chlorides], and lactates 1*15 Soda, yvith animal matter soluble only in water 0*75 100*00 4. This chemist found the same ingredients, united in somewhat different proportions, in the vitreous humour. 5. 100 parts of the crystalline lens were found by Ber- zelius to be composed of Water Peculiar matter Muriates [chlorides], lactates, and animal mat- 1 ter soluble in alcohol J Animal matter soluble only in water, with some 1 phosphates J Portions of remaining insoluble cellular membrane 100-0 6. The peculiar matter, mentioned in the foregoing analy- sis, was found to have all the characters of the colouring matter of the blood, except the colour. When burnt, it leaves a small residue, containing a very small quantity of iron. 58*0 35*9 2*4 1*3 2*4 OPTIC HUMOURS—LIQUOR OF THE PERICARDIUM—SINOVIA. 557 7. Leopold Gmelin has been enabled to ascertain several Chap. II. of the properties of the black pigment, found on the choroid pr„(K.rties coat of the eye. He collected 75 grains of this substance of the black from 500 eyes of oxen and calves. It has a blackish-brown fiJ^o? colour, and no taste. When applied to the tongue, it ad- the ox. heres like clay. It is insoluble in water, alcohol, ether or oils, but dissolves in solutions of potash or of ammonia, from which it may be precipitated by acids. How far the black pigment, on the same coat of the human eye, may possess similar properties, remains yet to be ascertained. SECTION XII. OF THE LIQUOR OF THE PERICARDIUM. 1. Dr. Bostock has examined this liquor, obtained from a Liquor ol boy who had died suddenly. He considers it to be compo- ^JJJ* sed of the following constituents. Water 92.0 Albumen 5'5 Mucus 2-0 Chloride of sodium (common salt) 0-5 1000 SECTION XIII. OF S1N0VIA. 1. Sinovia is a peculiar slippery liquid, found in the capsular ligaments of joints, and intended to facilitate the motion of bones upon each other. ... 2. Margueron has analyzed this liquid, as it exists '" Ana^of the joints of the ox. How far it may be the same in iheofthew. human joint remains yet to be ascertained. In the mean^ «»- time, it may not be uninstructive to give the result of thwjj^ chemist's analysis. ,. , ron* 3. When sinovia is treated with alcohol, a white sub- stance precipitates, possessing all the properties of albumen. After this is separated, the liquid continues as viscid as at first; but if acetic acid be added, it loses its viscidity, and there precipitates a peculiar fibrous substance having the colour, smell, taste and elasticity of vegetable gluten. If this fibrous matter be separated, and the remaining liquid --g ANALYSIS OF HEALTHY PRODUCTS. Part il concentrated by evaporation, crystals of acetate of soda arc Boor HI. fleposiitd. which indicate the presence of soda. Wncn the sinovia is exposed to a dry atmosphere, its aqueous parts gradually evaporate, and there remains a scaly rcbiouum, in which cubic crystals of c loride of sodium, and a saline efflorescence consisting of carbonate of soda make their appearance. When exposed to destructive distillation, the products are water, the same liquid containing ammonia, empyreumitic oil, and carbonate of ammonia. The residue is a coal, containing some phosphate of lime. Its compo- 4. According to Margueron, the constituents of sinovia siuon. just given are combined in the folloyving proportions. Fibrous matter 11*86 Albumen 4"52 Soda *71 Chloride of sodium (common salt) 1*75 Phosphate of lime *7° Water 80'46 100*00 «. Secretions of an Excremmtitiovs Nature. These secretions are Urine and Sweat. SECTION XIV. OF URINE. Researches 1. This animal secretion engaged the attention of che- into the na- mists at a very early period, as being the liquid from which tUiee°made phosphorus was first obtained. The labours of the early bTseyTrai chemists were chiefly directed to obtaining the phosphoric chemists. salts> scheele yvas perhaps the first chemist, who advanced considerably the knowledge of the component parts of urine, by discovering several substances not before suspected to exist in it. Since his time, Cruickshanks, Proust, Fourcroy and Vauquelin, and Berzelius have made a complete inves- tigation of its properties. Healthy 2. Healthy urine, at the time it is voided, is a transparent urine de- liquid, of a light amber colour, aromatic odour, and dis- ,cribed. agreeable bitter taste. Its specific gravity varies from 1*005 to 1*033. Upon cooling, it loses its aromatic odour, and acquires a urinous one. In a feyv days, by standing, it ac- URINr 559 quires an odour resembling that of sour milk, and ultimately chap. II. an alkaline smell. 3. By much the greatest bulk of urine consists of yvater. it contains, Berzelius has ascertained, that, in healthy urine, 933 parts L Water: in the lOOO are water. 4. It urine be evaporated by a slow fire to the consistence of a syrup, it will have a deep brown colour, and exhale a fetid ammoniacal odour. When this syrup cools, it forms a crystallized mass, consisting of all the component parts of urine. It this mass be treated with four times its weight of alcohol and slightly heated, a part of it is dissolved, and the alcohol assumes a brown colour. If the alcoholic solu- tion be dis.ill -d in a retort at a sand heat, until it is reduced to the consistence of a svrup, at which period all the alcohol will have been driven off, the mass obtained, upon cooling, assumes the form of crystals. These crystals consist of 2. Urea, up a. i his peculiar substance constitutes about 30 parts in ^J^ every 1000 of urine, including the water; but if the aqueous teristicin- portion be excluded, it forms nearly one-half of this seen.- gredient: tion. Urea is characteristic of this liquid, and possesses its taste and smell. Its presence in urine may be detected, very readily, by evaporating this liquid to the consistence of syrup, and then adding concentrated nitric acid. This acid will fall down, combined with the urea, in the form of yvhite shining crystals.* 5. Urine is capable of converting some vegetable blues to red. The uncombined acid, which is thereby indicated, was first supposed to be the phosphoric acid, and afterwards the acetic acid by Thenard; but Berzelius has shown, that it is the lactic acid. Besides uncombined lactic acid, Berzelius ^.Lactk has detected in urine, lactate of ammonia, and a peculiar J^^od, animal matter together with some urea which cannot be and animal separated from it. These three ingredients, according to ™«er: Berzelius, constitute 17*14 parts of urine in the 1000. 6 If urine be slowly evaporated to the consistence ot 4 Chloride svrup, a number of crystals will make their appearance on °f sodium: its surface. These crystals are found to consist of chloride of sodium (common salt). ... ^v. 7 If urine be acidulated with nitric acid to prevent the precipitation of the phosphates which it contains, upon the addition of chloride of barium (muriate of barytes), a pre- cipitate falls consisting of sulphate of barytes. This precipi- 5 Sulphates and of soda: ^ • •,„. ,„i,ovc a «lear idea of the nature of urine, would do memory on the subject of their properties. 560 ANALYSIS OF HEALTHY PRODUCTS. Paut ii. tation demonstrates the presence of sulphuric acid in urine* BooR "L It has been ascertained, that it exists in combination with potash and soda. These facts were made knoyvn by Berzelius. 8. If the saline mass, which remains after the separation of urea by the action of alcohol from crystallized urine, be dissolved in a sufficient quantity of hot water, and allowed to crystallize spontaneously in a close vessel, two distinct sets of crystals will be formed. They may be separated from each other by exposure to a dry atmosphere; the upper- most set will effloresce and fall to powder, yvhile the low- 6. Phos- ermost set will remain unaltered. The former is found to sodTand of consistof phosphate of soda united to a small quantity of phos- ammonia. phate of ammonia; whereas the latter is composed of phosphate of ammonia combined with a small portion of phosphate of soda. These salts, as they exist in the impure saline mass above alluded to, were formerly known by the names of fu- sible salt of urine and microcosmic salt. 7. Hydro- 9. When urine is cautiously evaporated, cubic crystals chiorateof may 0ften Dt. discovered among its salts. These crystals are ascertained to consist of hydrochlorate (muriate) of am- monia. 8 Phos- 10. If liquid ammonia be added to fresh urine, a white pow- phates of der precipitates, which is found to be phosphate of lime con- magnesia, taining a little magnesia. The magnesia is ascertained to be and hydro- derived from some phosphate of magnesia, which is de- limef ° composed by the action of the ammonia. The phosphate of lime contains also, according to Berzelius, a minute portion of hydrofluate (fluate) of lime. *3.Uricacid. 11. If urine be evaporated to -jy^th part of its weight, it lets fall a subtle powder, which adheres firmly to the bottom of the vessel employed. This substance is uric acid. The quantity of this acid contained in urine is very variable. The brick-red substance, which is deposited when urine cools, is composed of phosphate of lime and uric acid. The presence of the uric acid may be made evident by dissolv- ing the sediment in diluted nitric acid. If the solution, upon being evaporated to dryness, assume a fine rose colour, uric acid is present. This solution consists of purpurate of ammonia. \o. Mucus: 12. The cloud, yvhich forms in urine as it cools, is ascer- and tained to consist of the mucus of the bladder. It may be separated by the filter. n. Silica. 13. Besides the substances already enumerated as consti- tuents of urinej"- Berzelius has detected a very minute por- tion of silica in healthy urine. ORlNE 561 COHStitU- 933*00 30*lO eNtf: of urine c-coritmg to Berzelius. 17*14 4*45 3*71 3*16 2*94 1*65 1*50 1*00 1*00 0*32 0*03 14. The following table exhibits the result of Berzelius's Chap, il analysis of 1000 parts of healthy urine. Water Urea Free lactic add; lactate o'f ammonia; and "J animal matter, containing urea not scpa- > rable from it J Chloride of sodium (muriate of soda). Sulphate of potash Sulphate of soda Phosphate of soda Phosphate of ammonia Hydrochlorate (muriate) of ammonia Phosphates of lime and of magnesia, with a 1 trace of hydrofluate (fluate) of lime j Uric acid Mucus of the bladder Silica 1000-00 15. Besides these constituents of urine, as ascertained by Resides Berzelius, other chemists have detected substances not men- JtuentT tioned by him. there have 16. When fresh urine is put under the receiver of an air- ^J^y pump, air bubbles are extricated, which prove to consist of others, carbonic acid. The presence of this acid in urine was first ^.arbonic ascertained b\ Proust. 1". If hydrochloric (muriatic) acid be added to fresh 2. Benzoic urine, previously evaporated to the consistence ot a syrup, a precipitate appears, yvhich has all the properties of benzoic acid. The quantity of this acid in urine varies in amount from one to ten parts in 10,000. 18. If an infusion of tannin be dropt into urine, a white 3. Albumen precipitate appears, which has been ascertained to consist of ^JseIat,n: tannin, combined yvith albumen and gelatin. This precipi- tate, according to Cruickshanks, amounts to one part in 240 of healthy urine. 19. When urine is boiled in a silver basin, it blackens the 4.SujPhur metal; and if employed in sufficient quantity, small crusts of sulphuret of silver are formed. These facts prove the *prtsence of uncombined sulphur in urine. 20. Hence it appears, that, besides the substances enu- merated in Berzelius's analysis, urine contains carbonic and benzoic acids, albumen and gelatin, and sulphur. 21. The ultimate constituents of urine are oxygen, chlo- rine, fluorine, azote, hydrogen, carbon, phosphorus, sulphur, potassium, sodium, calcium, magnesium, and silicum. 4 B 562 ANALYSIS OF HEALTHY PRODUCT> Part II. 22. The urine is altered considerably in its properties, "OOK Hl under the different circumstances of tnabh and disease. In the following paragraphs, the most remarkable of these al- terations are noticed. 23. The quantity of urea contained in urine is very vari- able. In the urine voided soon after a meal, scarcely any urea can be detected. In chronic hepatitis, Hose has ascer- tained, that the urine contains no urea. This faci h is been confirmed by Dr. Henry. The urine yvhich flows during hysterical paroxysms is known to be abundant and quite limpid. Urine, voided under such circumstances, contains scarcely any urea or gelatin, but a large proportion of salts'. 24. Phosphate of lime is said to abound in the urine of rickety patients. The presence of this salt in excess, in the urine, might very reasonably be expected in this disease. It is, however, contended by some, that the morbid peculiarity of the urine of rickety patients consists in the presence of oxalate of lime. Pink-co- 25. The pink-coloured sediment, which appears towards loured sedi- the close of some diseases, and is called by physicians the la- urme. tcritious sediment from its brick colour, was considered by Scheele to consist of uric acid, mixed with some phosphate of lime. Prou t, hoyvever, finds the acid of this sediment to diffVr from uric acid in several particulars; and, considering it as peculiar, has given it the name of rosacic acid. Ac- cording to Proust, the lateritious sediment is composed of rosacic acid, mixed with a small proportion of uric acid and phosphate of lime. Prout considers it probable, that it is his neyvly discovered acid (purpuric acid), combined with am- monia, or perhaps occasionally with soda.* This sediment is deposited towards the termination of fevers, especially of the intermittent type. It falls also towards the termination of a paroxysm of gout, and during the course of diseases of the liver. Attention to the appearance of this sediment in urine becomes important, as it indicates the close ot most inflammatory diseases. 26. The quantity.of albumen in urine is very much in- creased in certain diseases. It has already been stated, that the proportion of this substance in healthy urine is very Albumen of small. In general dropsy, the urine is loaded with albumen, urine, en- whiCh may be coagultted by heat, or at least bv acids. In creasedin - » 7 . * - , »eneiai dropsy, however, complicated yvith disease ot the liver, tne dropsy, but urine contains no albumen, but is hip-h-coloured and scanty, notmdron- .... ,. ^ lT7| , ,. .- sy from dis-and deposites the lateritious sediment. When the digestive eased liver. ______ * Prout, Phil. Trans. (1818). Part II. 420. SWEAT. 563 process is imperfectly performed, the urine is found to fur- ChaMI. nish a copious precipitate with tannin. This precipitate is ascertained to be tannin, combined with albumen and gela- tin. The presence of albumen and gelatin, in large propor- tion in urine, is indicated, if it speedily take on the putre- factive process. In some cases, urine becomes putrid as soon as voided. This occurrence may always be taken as a sure indication of some defect in the powers of the digestive organs. 27. Bile is sometimes found in small quantities in the Urine con- urine, especially in iaundice. It mav be detected by the ad-tains4P,,e In dition of hydrochloric acid, which, if bile be present, will render the urine green. 28. The urine, in the disease called diabetes, has a sweet and saccha- taste, and is found to contain a large quantity of saccharine [nndeia"etes.r matter. In one case, recorded by Dr. Bostock, the sugar contained in the urine, yvhich a patient discharged in twenty- four hours, amounted to twenty-nine ounces. 29. The tendency of urine to putrefaction seems to de- Urine pu- pend upon the facility, with yvhich its most remarkable in-*^Jv> on gredient, urea, suffers decomposition. The products of this account of decomposition are acetic and carbonic acids, and ammo- ;yet^,'(|,ed.en' nia; and hence the ammoniacal smell, which attends the pu- composition trefaction of urinv. The ammonia, thus formed, neutralizes of urea. the free lactic acid present in the urine; and, as a conse- quence, the phosphate of lime precipitates, it having been held in solution by this acid. It also combines yvith the phosphate of magnesia, yvith which it forms a triple salt. It neutralizes the uric and benzoic acids naturally present in the urine, and likewise the acetic and carbonic acids, the products of the putrefaction. Notwithstanding all these com- binations, into yvhich the ammonia enters, it still remains in excess. From this statement, it may be inferred, that the putrefaction of urine results in the formation of a number of salts, all of which contain ammonia. SECTION XV. OF SWEAT. 1 It has been ascertained by experiment, that an invisi- Matter is bie vapour is constantly separating from the surface of the j™^ body. This vapour is called insensible perspiration. Under tncskin. peculiar circumstances, however, the matter, which passes through the skin, assumes the liquid form, and then it >s known by the name of syveat. 564 ANALYSIS OF HEALTHY PRODUCTS. Part ii. 2. The amount of the insensible perspiration, for a given Boor in. time, has not been precisely determined. Cruickshanks, Amount of who ascertained the insensible perspiration of the hand for insensible a given time, calculates that for the yvhole body, to be, on Son^caicu- an average, seven pounds six ounces troy, for tyventy-tour lated by se- hours. Lavoisier and Seguin made experiments of a much reenters? more accurate nature, to elucidate the same point. These chemists noted the yveight, lost by an individual, in a given time, both by respiration and perspiration. They afterwards ascertained the loss, for the same time, by respiration alone. This they were enabled to do, by enclosing the same person in a bag of varnished silk, completely impervious to air or vapour, and so arranged, by glueing the edge of a slit in it to the circumference of the mouth, as that respiration might be carried on in the open air without inconvenience. By this contrivance, all the matter emitted by the lungs yvas lost, yvhile that emitted by the surface of the skin yvas re- tained in the bag. The difference in yveight of the subject of the experiment, just after entering the bag and just be- fore leaving it, must give the amount of loss by respiration alone; and this amount, subtracted from the loss occuring on both accounts, will give the amount of the insensible per- spiration. In this way, Lavoisier and Seguin ascertained, that the maximum of perspired matter in a minute was 26*25 grains troy, and the minimum, 9 grains; which, calculated at a medium, gives 4 lbs. 4*89 ounces as the average amount of perspired matter for twenty-four hours. Sweat con- 3. Syveat is chiefly composed of yvater; but besides this ifwater: ''quid, several other substances have been discovered in it. 4. Air, which has remained for a long time in contact yvith the skin, is found to consist almost entirely of carbonic acid. There being no increase in the bulk of the air thus changed, it becomes a question, how the change is effected. 2. Carbon: Either carbon must be emitted and after.vards become car- bonic acid, or oxygen gas must be absorbed and carbonic acid ready formed be subsequently throyvn out. 3. Lactic 5. Sweat contains an acid. This yvas at first supposed to acid.- be the phosphoric acid, and afterwards, by Thenard, acetic acid; but Berzelius has rendered it probable, that the acid of sweat is the lactic acid. 4. Animal 6. A small quantity of animal matter was obtained from matter.- SWeat by Thenard. This chemist supposes it to be similar to gelatin in its nature. 5. Oily mat- 7. Besides these ingredients, sweat undoubtedly contains t6r- an oih matter, from yvhich Cruickshanks believes it to de- rive its odorous properties. It is well knoyvn, that the dog can distinguish his master by the scent. This seems to SEMEN—MILK. 565 prove, not only the odorous nature of the perspiration, but also its peculiarity in every individual. In the negro, the odorous part of the perspiration is in great abundance. Cuap.1I men. /. Secretions dependent upon Sexual Organization. These secretions are Semen, Milk, and the Liquor of the Amnios. SECTION XVI. OF SEMEN. 1. Semen is the liquid, secreted by the testes, and intend- ed for the impregnation of the female. Heretofore only hu- man semen and the milt of certain fishes have been subjected to analysis. It is intended in this section to notice the che- mical nature of the former. 2. Vauquelin analyzed human semen in 1794, and found Analysis ot it to be possessed of the following properties. When newly ejected, it is evidently a mixture of two different substances; the one, liquid and milky and considered to be the secretion of the prostate gland, the other, thick and mucilaginous, which appears to be the true secretion of the testes. Its smell is slightly disagreeable, and its taste acrid and irrita- ting. Its specific gravity is greater than that of water. As it cools, the mucilaginous part becomes transparent, and ac- quires greater consistency; but, by the expiration of twenty minutes, it has liquefied." Before this spontaneous liquefac- tion, semen is insoluble in water, but afterwards dissolves in this liquid. . c 1nn 3. Vauquelin gives the following constituents for 100 parts of semen: Water 9° Mucilage [mucus] » Phosphate of lime 3 Soda [carbonate of soda] __*_ 100 SECTION XVII. OF MILK. 1 Milk is the peculiar liquid, secreted by certain glands with wh ch he female of a particular class of animals called Mammalia is furnished, and intended for the nourishment of the offspring. 566 ANALYSIS OF HEALTHY PRODUCTS Part II. 2. According to the plan proposed to be adopted in this _Book HL wor]Ci human milk should alone come under notice. But as Co»s'milk, cows' milk constitutes a very important part of the food of thUsecuon. man* an(* *s the milk upon which the greatest number of experiments have been made; it is proposed in this section to giy e the analysis of cows' milk, and afterwards to take a comparative vieyv of human milk. Its proper- 3. The sensible qualities of cows' milk are too well known **e8* to require detail. Its boiling and freezing points are very nearly the same yvith those of water. Its specific gravity is between that of water and of blood. It reddens vegetable blues. It is easily 4. Milk may be readily separated into three parts. When ■eparated allowed to remain at rest for some time, a thick unctuous cream, curd yellow substance collects on it** surface, denominated cream. and whey. After this substance is separated by skimming, the liquid which remains is much thinner than unskimmed milk, and has a bluish-white colour. Skim-milk, by being heated to the temperature of about 100° and the addition of a little rennet,* coagulates into a solid tremulous mass. This mass, upon being broken into pieces, separates into two distinct parts; the one solid called curd, the other liquid called whey. l. Cream 5. The peculiar nature of cream is derived from the pre- consistsof sence 0f a concrete oil; but besides this oil, cream contains ed with both curd and whey. The oil may be separated from the curd and curd and whey by agitation. It constitutes the well known w ey" article of food, called butter; and the mechanical process, by which it is separated, is called churning. 6. Butter, as it is commonly made, still contains a por- tion of curd and of whey. If heated to the temperature of 96°, it melts, becomes transparent, and has the appearance of an oil. If kept for some time in a melted state,- a little curd and whey separate from it; but, after this separation, it has lost its peculiar flavour. 7. Berzelius has ascertained, that the ingredients of cream are united in the following proportions: Butter 4*5 Cheese [curd] 3*5 Whey 92*0 100-0 8. Thus it appears, that cream contains between 4 and 5 per cent, of butter; and that butter-milk consists of curd and whey without any oily part. • Rennet is water, which has been digested upon the inner coat of the calf's stomach, and preserved with salt. MILK. 567 9. Butter may be obtained by agitating or churning milk Chap, ii. newly drawn from the cow; and in this case a larger pro- Butter ob- portion ot butter is afforded. It has been ascertained also, ^V* that skim-milk and even yvhey still continue to contain a ^^ portion of the oily part of milk, and may be made to yield butter by churning. Sour cream, however, is generally pre- ferred for making butter. Such cream yields as much but- ter as fresh cream, and requires but one-fourth as much churning. It is not known in what way the acidity of the cream operates; but it has been observed, that butter pro- duced from such cream is as sweet as any other, while the butter-milk itself is not so sour as the cream from which it had been formed. Hence there is an evident disappearance of acidity. The manner in which churning acts is not well understood. It is said to effect the separation of butter, even though the contact of air be prevented. lo! The usual means, by which skim -milk is separated into ftCjJ de- curd and whey, have already been pointed out. Curd is a white solid substance, possessing a good deal of brittleness when completely separated from the aqueous parts. It may be precipitated from skim-milk by means of acids, which fall in combination with it. It mav be afterwards disengaged from these combinations, by digesting them in the solution of some salifiable base, which forms an insoluble compound with the acid present. The acid combines with such base, and the liberated curd dissolves in the water. Curd, ren- dered soluble in this way, is somewhat altered in its proper- ties. Its solution has a yellow colour, and some resem- blance in appearance to a solution of gum. When evapora- ted to dryness, it leaves a yellow m ss which is readily so- luble in water. When its solution is boiled, a P^le forms upon its surface, nearly insoluble in water and similar to that, which is formed upon boiling milk. Curd appears toUjjtad be closely allied to coagulated albumen in properties. « is.te€lalbu. composed ot oxygen, azote, hydrogen and carbon. m^'msthc 11. Curd is the part of milk from which cheese is made. Itformstbe The richness and good quality of this article offo°dd^ cheese. peud very much upon the quantity of the cream^ or oily part of milk, which may be allowed to remain in it. If the curd be too much heated and too forcibly pressed,, a nch whey is driven out and an infer-tor cheese is formed. On the contrary, it the hea ^ not so grea^ jan ^ m^m'tl^^ ^ ■* 'Tl Whfv'asitis generally obtained, is rendered im-,Whe pure by admixture of curd. It may be separated from the 568 ANALYSIS OF HEALTHY PRODUCTS Pam IL latter by first filtering, and afteryvards boiling it for some Book IH. t\mti) anci carefully separating the scum yvhich collects on its surface. Whey, when thus rendered pure, is a transpa- rent liquid of a yellowish-green colour and syveetish taste. It reddens vegetable blues, owing to the presence of lactic acid. The greater part of it consists of water. When sloyvly evaporated, it at last deposites a number of yvhite crystals consisting of sugar of milk. Besides this substance, it con- tains the chlorides of sodium and of potassium (muriates of soda and of potash), the phosphates of lime and of magne- sia, sulphate of potash, a peculiar extractive, and, according to Fourcroy and Vauquelin, phosphate of iron. Gomposi- 13. According to Berzelius 1000 parts of milk, deprived ti°Its0ff°°° °^ *ts cream» are composed of skim-milk. Water 928*75 Curd with a little cream 28*00 Sugar of milk 35*00 Chloride of potassium (muriate of potash) 1 *70 Phosphate of potash 0-25 Lactic acid, acetate of potash, with a trace "I fi>QO of lactate of iron J Earthy phosphates (phosphates of lime and 1 of magnesia) j >*30 1000*00 14. This 'analysis of Berzelius of skim-milk, by ex- cluding the curd, may be considered as giving the con- stituents of whey. When taken with this exception, it is perceived, that it indicates the same constituents for this part of milk, as those already given upon the authority of other chemists; with the exception of chloride of sodium (common salt), sulphate of potash and phosphate of iron,* not found by Berzelius, and with the addition of phosphate and acetate of potash, and lactate of iron, detected by this chemist alone. With regard to the iron, it is seen, that Berzelius differs, from Fourcroy and Vauquelin in finding it combined with lactic acid, instead of phosphoric acid. 15. As cream is composed of butter, curd and whey, Berzelius's analysis of skim-milk may be considered as containing every ingredient of milk, except the oil or but- ter. Taking his analysis, therefore, yvith this addition, milk may be stated as having the following ultimate constituents; namely, oxygen, chlorine, azote, hydrogen, carbon, phos- phorus, potassium, calcium, magnesium and iron. Woman's *6» Woman's milk differs from cows' milk in the fol- miik, com- lowing particulars. Its taste is much sweeter. It forms, cows' miW. when allowed to remain at rest, a more abundant cream. LIQUOR OF THE AMNIOS—PUS. 569 which, however, cannot be made to yield butter. It does Chap. II. not coagulate by any of the means which succeed with cows' milk; but this does not depend upon the absence of curd, but arises from the small portion which it contains of that ingredient of milk. Human milk yields a larger proportion of sugar of milk than cow's milk. These are the principal differences between cows' milk and human milk. SECTION XVIII. OF THE LIQUOR OF THE AMNIOS. 1. The foetus in utero is contained in a membranous bag, Liquor of called the amnios. The liquor of the amnios is the liquid, Jhe n'^'uHn with which this bag is filled, and in which the foetus swims, which the 2. This liquor, in the human female, has a slight milky ^s. colour, a weak pleasant odour, and a saltish taste. When evaporated to dryness, 98*8 per cent, are driven off in the form of water, and the residue, amounting to 1*2 per cent. consists of albumen, chloride of sodium (common salt), car- bonate of soda, phosphate and carbonate of lime. III. MORBID PRODUCTS. The morbid products of the human body come next un- Morbid .. .' m, -.i products der consideration: 1 hese are either are eithel: a. Morbid secretions; as pus, liquor of dropsy, and liquor of *c^°™ blisters; or . tions. b. Morbid concretions; which will be noticed under the titles of concretions with basis of phosphate of lime, biliary concretions, urinary concretions, and gouty concretions. Morbid products, thus arranged, will be treated of in the seven following sections. a. Morbid Secretions. These secretions are, Pus, Liquor of dropsy, and Liquor of-blisters. _ , SECTION I. OF PUS. Pus is the thick liquid, secreted generally by the surface Pusisof of an open sore. There are, however, a great many shades g»j««* of difference in this animal product, as secreted from sores 4C 570 ANALYSIS OF MORBID PRODUCTS. Paft ii. in different states. One kind of it, which always attends an Book in. uicer while in a healing condition, is generally called good pus. It is proposed first to consider this kind, and after- yvards those modifications, which do not indicate a repara- tion of injured parts. Good pus I. Good pus is a liquid about the consistence of cream. described, t. i nil- . • •» 1 It has a yelloyvisn-white colour, an insipid taste, and no smell yvhen cold. When viewed through the microscope, it has the appearance of a transparent liquid, in which white globules are swimming. Its specific gravity is somewhat greater than that of yvater. Hence, when thrown into this liquid, it sinks. It does not mix readily with water. By slight agit.ition, it forms a milky liquid, but the pus sub- sides again by rest. Nevertheless, by repeated agitation, a permanent mixture may be formed, which passes through the filter unaltered. Action of Pus forms with sulphuric acid a purple-coloured solution, ereacuL°n8 ^rom whicn it may be precipitated by the addition of water. It dissolves with effervescence in concentrated nitric acid, forming a yelloyv-coloured solution, from which when re- cent it may be throyvn down, in the form of grey flakes, by the addition of water. A similar solution may be made in hydrochloric acid by the assistance of heat, and decompos- ed in like manner. The facts, last stated, are sufficient to distinguish pus from mucus, a discrimination of some im- portance yvith regard to expectorated matter. andofalco- Pus, when treated with alcohol, is not dissolved, but h°l« thickened. With solutions of potash or soda, it forms a whitish ropy liquid, which is decomposed by water. Am- monia first reduces it to the state of a transparent jelly, and then dissolves it partially. When pus is dried at a moderate heat, it assumes the ap- pearance of horn. When exposed to destructive distillation, the chief products are yvater, ammonia, carbonate of ammo- nia, and an empyreumatic oil. The residuum is a light bril- liant coal, containing traces of iron. No precise analysis has been made of pus; but from what has been already said, it is obvious, that it bears considera- ble analogy to albumen. Iti-condi- II. Ill-conditioned pus.—There are a great many shades uoned pus 0f difference in ill-conditioned pus. It has an acrid irritating is ot several _ . , ., . ,r , . , ,° kinds. nature, a fetid smell, and much less consistence than good- conditioned pus. That secreted by what is called the hos- pital sore has been examined by Mr. Cruickshanks. It pos- sessed most of the properties of good-conditioned pus. Its fetid odour yvas not destroyed, but changed by lime water: it yvas increased by sulphuric acid or alcohol; but was des- i LIQUOR OF DROPSY 571 troyed by nitric acid and nitrate of mercury, by perchloride Chap, ii. of mercury and chlorine. These latter substances, there- fore, are considered by Cruickshanks as the proper washes for destroying the foetor of ill-conditioned ulcers. III. Matter of cancer.— This matter has been examined Matter by Dr. Crawford. It changes some vegetable blues to green, ][™£ bv indicating the presence of an alkaline base. When treated described.' with sulphuric acid, a gas is extricated, having the proper- ties of hydrosulphuric acid (sulphuretted hydrogen). Dr. Crawford supposes, tha- this acid exists in the matter com- bined with potash. Its odour is completely destroyed by chlorine. Hence this supporter is recommended as the best wash for cancerous ulcers. IV. Expectorated matter.—Dr. Pearson has examined Expectora- with much care the different kinds of expectorated matter,ted matter of which he enumerates seven. All these kinds, excluding true pus, he finds to consist of water, holding in solution a quantity of albumen in a state of combination with potash, together with a number of salts in small proportion, and traces of sulphur, phosphorus, and oxidized iron. SECTION II. OF THE LIQUOR OF DROPSY. 1. This liquor has a yellowish-green colour, and is some- Liquor of times transparent and sometimes turbid. A colourless li- scrib/d> quor, extracted from a dropsical patient and examined by Wurzer was found to contain albumen, mucus, hydrosul- phuric acid (sulphuretted hydrogen) phosphate of lime chloride of sodium (common salt), and soda. Dr. Bostock analyzed a liquor, obtained by puncturing a tumour on the spine, and found it composed of the following constituents. Water 7'8 Chloride of sodium (muriate of soda) 1*0 Albumen °'5 Mucus and gelatin u'7 T . trace Lime _____ 100-0 572 ANALYSIS OF MORBID PRODUCTS- Part II. Book III. SECTION III. LIQUOR OF BLISTERS. Constitu- 1. Margueron has ascertained, that this liquor is composed entsofthe of the following constituents. SK* Water 78 Albumen * 8 Chloride of sodium (muriate of soda) 2 Carbonate of soda * Phosphate of lime 1 100 b. Morbid Concretions. These are, Concretions with basis of phosphate of lime, Biliary Concretions, Urinary Concretions, and Gouty Con- cretions. SECTION IV. CONCRETIONS WITH BASIS OF PHOSPHATE OF LIME. Concre- Under this title may be enumerated the following con- Sri'rf* cretions* phosphate I. Pineal concretions.Smsll concretions, about the size of lime are, 0f grains of sand, are frequently found in that part of the l. Pineal t>rain, called the pineal gland. Dr. Wollaston has ascertain- tio>.s. ed that they are composed of phosphate of lime. 2. saiirary H. Salivary concretions.—Small concretions are some- Uons™5 times found in the salivary glands, especially the parotid and sublingual. By the experiments of Wollaston, Four- croy and others, it is ascertained, that these bodies are composed of phosphate of lime, together with a mem- branous substance, which remains undissolved, preserv- ing the shape of the concretion, after the phosphate is re- moved by the action of an acid. The pancreatic concretions are supposed not to differ from these concretions. 3.Puimo- III. Pulmonary Concretions.—Small, round, white con- cretions' cret*ons are frequently coughed up by persons suffering un- der diseases of the lungs. They are found generally to con- sist of phosphate of lime, united to a membranous sub- stance, which remains and retains the shape of the concre- tion, after the phosphate itself is removed by a corrosive acid. Occasionally these concretions have been found to be composed of carbonate of lime. PHOSPHATE OF LIME CONCRETIONS—BILIARV CONCRETIONS. 573 Chat. II. SECTION V. OF BILIARY CONCRETIONS, OR GALL-STONES. 1. Concretions occasionally form in the gall-bladder, Biliary con- and, by getting into the gall-duct, prevent the flow of the f™Jn0jn,t|ie bile into the intestines, and are thereby a cause of jaundice, gaii-blad- It is, therefore, of some importance to the practitioner to der* be acquainted with the chemical nature of these substances. 2. Several different kinds of biliary concretions have been They are distinguished, founded upon their external characters. undT™1 3. One species has a white colour, and a crystallized, shining, lamellated structure. Occasionally its colour is yel- low or greenish. One only of this kind of biliary concretion is found at a time in the gall-bladder. It is sometimes as large as a pigeon's egg, but generally much smaller. It is formed invariably upon a nucleus of inspissated bile. Its specific gravity is less than that of water. When exposed to a heat of about 278°, it softens and melts, assuming the ap- pearance of oil and giving out at the same time the odour of melted wax. When the heat is withdrawn, it again crys- tallizes as it solidifies. It is insoluble in water, but dis- solvt s in hot alcohol, from which it deposites in brilliant plates upon cooling. It is soluble also in oil of turpentine. From these facts, it is evident, that this species of concre- tion is composed of a peculiar matter. This matter, from its resemblance both to fat and wax, was called by Four- croy adipocire. Chevreul, however, has examined it more lately, and finds it to possess properties, distinct from those of adipocire, and proposes to call it chole*ferine. Pelletier and Caventou have investigated the action of nitric acid on this substance, and find that it becomes converted into a peculiar acid substance, which they propose to call choles- teric acid. This new acid is capable of forming salts with the different salifiable bases. 4. Biliary concretions, belonging to the species next to be noticed, have a polygonal shape, and light greyish-brown colour. When broken they exhihit a structure, composed ot an exterior thin crust, consisting of concentric layers alter- nately crystallized, and enveloping a nucleus, formed ot a substance resembling granulated honey. Dr. Thomson ana- lyzed six gall-stones of this kind, and found them to con- tain 96 per cent, of adipocire. The remainder was made up of some picromel, and a very small portion of a substance resembling albumen. . 5. Besides these kinds of biliary concretions, Thenard has described a species consisting of altered matter of bile: 574 ANALYSIS OF MORBID PRODUCTS. Part II and Dr. Saunders another, the stones belonging to yvhich Book in. arR insoluble both in alcohol and spines of turpentine, are not inflammable, but, when exposed to heat, become red, and waste away to ashes. SECTION VI. OF URINARY CONCRETIONS. Urinary *• ^T 1S we^ knoyvn, that concretions sometimes form in concretions the human bladder, and give rise, by their presence, to one ^msV^ht ** of the most painful diseases, to which the body is liable. bladder. 2. At an early period, these concretions engaged the at- tention of physicians and chemists; in the hope, that the in- vestigation, by ascertaining their constituents, might lead to the discovery of the proper solvents when the stone is al- ready formed, or, when the tendency only to the formation is manifested, of the appropriate means of prevention; Firstaccu- 3. Very little advance was made in the investigation, rateiyexa- until Scheele, in 1776, published a dissertation on the subject Scheele and *n ^ Stockholm Transactions; which was folloyved by Bergman in some remarks by Bergman. No very important additions 1//6; who were raarie to the observations of Scheele and Bergman, lowed in until 1797, when Dr. Wollaston's experiments and observa- nce investi- tions appeared in the Philosophical Transactions, followed Wollaston the next year by a paper from Dr. Pearson on the same m 1797; by subject. The labours of these chemists were succeeded by i^sThv"1 a most complete dissertation on urinary calculi by Fourcroy Fourcroy & and Vauquelin in 1799; in the course of which, these che- inai79sTl»nd m*sts g*ve tnc result of their analysis of 500 calculi. In by Brande 1808, Brande published a paper in the Philosophical Trans- m 1808. actions, in yvhich he gives the result of the analysis of 150 calculi from the Hunterian Museum. 4. Urinary calculi are very various, both in their exter- nal appearance and in their composition. It would, there- fore, be impossible to describe them in general terms. It is proposed first to give an account of all the substances hitherto discovered in calculi, and afterwards the descrip- tion of the different species of these concretions, as founded upon their various chemical constitutions. Eleven sub- 5* The substances, heretofore discovered in urinary cal- stances culi, are the following: hare been i. Uric acid. 6. Magnesia. detected in 2. Phosphate of lime. 7. Phosphate of iron. calculi. 3. Phosphate of magnesia-and- 8. Silica. ammonia. 9. Urea. 4. Oxalate of lime. 10. Cistic oxide. ">. Hydrochlorate (muriate) of 11. Mucus. URINARY CONCRETIONS. 575 [l.] It has already been mentioned, that uric acid was Chap.ii. discovered by Scheele, while analyzing urinary calculi. It f uricacid, is by tar ;he most characteristic ingredient of urinary con - discovered cretions. All those analyzed by Scheele consisted entirely gc^£ bT of this acid. It was found in almost all the calculi analyzed by Pearson, Fourcroy and Vauquelin, and Brande, in larger or smaller amount. Ot 150 concretions analyzed by Brande, sixteen were found entirely composed of this acid. The prtsence ot uric acid is easily manifested by dissolving any calculus in a solution of potash or of soda, and precipitating the solution formed by the addition of a weak acid. The pit cipitate, if it consist of uric acid, will form the pink so- lution of purpurate of ammonia yvith nitric acid. 2.] Phosphate of lime yvas first detected as an ingredient 2. Phos- of urinary c.dculi by Bergman. It was afteryvards found by {^^j. other chemists, but Wollaston was the first to discover cal- detected by culi entirely composed of this salt. They yvere of a brown Bergman.. colour, smooth externally and polished, and composed of concentric layers, easily separable from each other. Calculi of the same chemical nature, examined by Fourcroy and Vauquelin, were white, friable, and stained the hands. [3.] Calculi, containing phosphate of magnesia-and-am- 3. Ammo- monia, were first noticed by Tennant, but were afterv ards ^['eh°sf" more fully investigated by Wollaston, and Fourcroy and magnesia. Vauquelin. This triple salt usually occurs in white semi- transparent layers, but sometimes on the surface of the cal- culus in crystals. [4.] Oxalate of lime was first detected in urinary calculi 4. Oxalate by Dr. Wollaston. Its presence characterizes the species of J^^f this concretion, previously denominated mulberry calculi ur. Wol-y from their shape. Calculi of this kind, examined by Dr. -aston. Wollaston, contained also phosphate of lime and uric acid; but Fourcroy and Vauquelin found some of this species combined only yvith animal matter. [5.] Hydrochlorate (muriate) of ammonia was first de- 5. Hydroeh- tected in calculi by Brande; who considers this to have ^^ been in reality the ammoniacal salt present in urinary cal-first noticed culi, announced as a urate by Fourcroy and Vauquelin. b> B™">e. Accordingly Brande does not believe, that any such salt as urate of ammonia exists in concretions of the bladder. [6 ] Alemani, an Italian apothecary, has detected magne- 6. Magnesia sia and phosphate of iron in a urinary calculus, which heand»™- subjected to analysis. [7.1 Silica, mixed with phosphate of lime, and occunng 7. silica. in calculi of the mulberry species, has been detected in two urinary concretions only of 600, which were examined by 576 ANALYSIS OF MORBID PRODUCTS. Paht ii. Fourcroy and Vauquelin. These calculi were particularly Book in. hard jn their texture. s.Ureafirst [8,3 ^he presence of urea in calculi was first ascertained detected My experimentally by Brande. Fourcroy and Vauquelin, how- Brande. ever, had previously suspected its existence in them. It may be obtained from the calculi which contain it, by digestion in water or alchohol, and subsequent evaporation. 9.Cistic [$•] Dr. Wollaston has detected a peculiar substance in oxide. calculi, to yvhich he has given the name of cistic oxide. A small calculus, entirely composed of this substance, was white, dense and brittle. It dissolved both in acids and in solutions of potash or soda, and formed, with either, crys- tallizable compounds. It was insoluble in water, alcohol or ether. When treated with nitric acid, it formed a solution, which was not pink-coloured, and from which the oxide might be precipitated by the addition of water. When dis- tilled, it yielded carbonate of ammonia and oil; and the re- sidue consisted of a small portion of phosphate of lime. 10. Animal [l0«] All calculi contain more or less of an animal mat- matter, ter, yvhich serves as a cement to keep together their other ingredients. This matter had been considered to be albu- men, but the more probable opinion is, that it is some modi- fication of mucus, derived from the bladder. 6. Having thus given short notices of the different sub- stances heretofore discovered in calculi, it will be next pro- per to give the classification of these bodies, as devised by different chemists. CNassinca- 7. By far the most complete classification of calculi is tion of cal- that pursued by Fourcroy and Vauquelin, founded upon the Fourcroy & results of the examination of 600 urinary concretions. These Vauquelin chemists divide them into three genera and twelve species. Swfi.812 The following is their arrangement: Genus I. Calculi composed of one ingredient. Sp. 1. Calculi composed of uric acid. Sp. 2. urate of ammonia. Sp. 3*...... ■ oxalate of lime. Genus II. Calculi composed of two ingredients. Sp. 1. Uric acid and the phosphates in layers. Sp. 2. Uric acid and the phosphates mixed. Sp. 3. Urate of ammonia and the phosphates in layers. Sp. 4. Urate of ammonia and the phosphates mixed. Sp. 5. The phosphates mixed or in layers. Sp. 6. Oxalate of lime and uric acid in layers. Sp. 7. Oxalate of lime and the phosphates in layers. URINARY CONCRETIONS. 577 Genus III. Calculi containing more than two ingredients. Chap.ii. Sp. 1. Uric acid or urate of ammonia, the phosphates and oxalate of lime. Sp. 2. Uric acid, urate of ammonia, the phosphates and silica. The following are the characters of these different spe- cies: Sp. 1. Uric acid.—Colour that of wood, with various First,or shades of red and yellow. Surface, usually smooth and po- "™;*?m1 ,. ■ i m / . i •• i f speciea. lished. lexture, laminar and radiated, compact and tine. Specific gravity, from 1*276 to 1*786. Soluble in solutions of potash or soda, without emitting the odour of ammonia. This species is by far the most common of all. Of the 600 calculi examined by Fourcroy and Vauquelin, one in every four belonged to this species. Sp. 2. Urate qf ammonia.—Colour brownish-white. Sur- Second spe- face often crystallized. Texture laminar. Laminae easilyc,e'' separable. Specific gravity, from 1*225 to 1*720. Soluble in hot water, especially if in the state of powder. Solution in potash or soda attended by the odour of ammonia. This is a very uncommon species. Brande considers the calculi be- longing to it to be in fact composed of uric acid, urea and hydrochlorate of ammonia. Sp. 3. Oxalate of lime.—Colour soot-brown. Surface co-Third, or ?ered with pointed or rounded protuberances, and hence j^^7 called the mulberry species, lexture dense and hard, re- sembling ivory. When sawn asunder, emitting the odour of semen. Specific gravity, from 1*428 to 1*976. Insoluble in potash or soda, but soluble, with difficulty, in acids. When burnt, leaves a residue of carbonate of lime. This species occurs frequently. Sp. 4. Uric acid and the phosphates in layers.—Surface Fourth spe- white like chalk, or sparry and semitransparent, according c,e»- as the exterior layer happens to consist of the phosphate of lime, or of the phosphate of magnesia. Often large. When cut asunder, a nucleus of uric acid presents. Specific gravi- ty very variable. One in every fifty calculi may be consi- dered as consisting of this species. Sp. 5. Uric acid and the phosphates mixed.—This species Fifth ipe- is very variable in its appearance. Specific gravity fromc,es- 1*213 to 1*739. Its proportional occurrence is about one in every forty calculi. Sp. 6. Urate of ammonia and the phosphates in layers.— Sixth spe- This species does not differ in external appearance from the c,es- fourth species; but when cut asunder, it presents a nucleus of urate of ammonia. It is not a common species. ^ Seventh Sp. 7. Urate qf ammonia and the phosphates mixed.—-This speciea. 4 D 578 ANALYSIS OF MORBID PRODUCTS. PAn-rTI. Boor III. Eighth spe cies. Ninth spe- cies. Tenth spe- cies. Eleventh species. Twelfth species. Arrange- ment of Fourcroy and Vau- quelin, very complete; that of Wollaston is more simple and species resembles the fifth, but may be distinguished from it, bv emitting the odour of ammonia when treated yvith potash. The calculi belonging to this species, are small and rather uncommon. Sp. 8. The phosphates mixed or in layers.—This species is white like chalk, friable, and soils the fingers like that substance. Texture laminar; laminae easily separable. Thin layers of phosphate of magnesia-and-ammonia, sparry and semitransparent, often interspersed. Specific gravity from 1*138 to 1*471. Soluble in acids, but insoluble in potash or soda. It occurs in the proportion of one in fifteen of the cal- culi, examined by Fourcroy and Vauquelin. Sp. 9. Oxalate of lime and uric acid in layers.—This spe- cies occurs either composed of a nucleus of oxalate of lime, covered by a layer of uric acid, or of a calculus of the mul- berry species, covered with a layer of the same acid. These varieties are easily manifested upon sawing the calculus in two. It occurs in the proportion of one in thirty. Sp. 10. Oxalate of lime and the phosphates in layers.— This species is characterized by a nucleus of oxalate of lime, covered with a coat of the phosphates. It agrees in ex- ternal appearance with several of the species, but its pecu- liar nature is rendered obvious, when the calculi belonging to it are cut asunder. Next to the uric species, this kind oc- curs most frequently in urinary calculi; being in the propor- tion of one in five of those examined by Fourcroy and Vau- quelin. Sp. 11. Uric acid or urate of ammonia, the phosphates, and oxalate of lime.—Calculi of this species have a nucleus of oxalate of lime, covered by a layer of uric acid, urate of ammonia, or a mixture of both, with an external coat of the phosphates. Sp. 12. Uric acid, urate of ammonia, the phosphates and si/ica.—Calculi belonging to this species have a nucleus, composed of silica and phosphate of lime, covered by a layer of uric acid and urate of ammonia, with an exterior coat of the phosphates. Calculi belonging to this species will resem- ble those of several other species. Their distinctive nature depends upon their internal arrangement. They are of very rare occurrence, four only having been heretofore observed. 8. The arrangement of Fourcroy and Vauquelin of uri- nary calculi is certainly very complete and satisfactory. Having had the advantage of examining a larger number of these concretions than any other chemists, their opportuni- ties yvere greater to observe the proportional occurrence of calculi chemically the same. In a practical point of view, however, so minute a division of calculi, as adopted by URINARY CONCRETIONS. 579 these chemists, can hardly be deemed of advantage. The Chap, il following arrangement bv Dr. Wollaston, in this respect, practical; answers much better. Calculi are divided by this chemist dividing ' calculi into into I. Uric calculi.—Under this name, are included such cal-l. Uric cal- culi as are wholly or chieflv composed of uric acid. This species may be considered as corresponding yvith Fourcroy and Vauquelin's first species. Calculi belonging to it are completely soluble, or very nearly so, in solutions of pure potash or soda. II. Fusible calculi.—This species includes such calculi as 2. Fusible are composed chiefly of phosphate of lime, and phosphate of magnesia-and-ammonia. It may be considered as corres- ponding, perhaps, with the 4th, 5th, 6th, 7th, 10th, 11th and 12th species in the arrangement of Fourcroy and Vauque- lin. The calculi belonging to it are distinguished by melting into an enamel before the blowpipe. They are completely soluble, or nearly so, in hydrochloric acid. III. Mulberry calauli___Under this name are included J-Muihw- by Dr. Wollaston, such calculi as are composed chiefly ofryo' oxalate of lime, or of oxalate of lime and phosphate of lime. This kind corresponds with the 3d, 10th and perhaps the 9th species of Fourcroy and Vauquelin's arrangement. They dissolve slowly, but completely or nearly so, in hydrochloric acid. When there is any residuum, it consists of uric acid. IV. Bone-earth calculi.—Under this epithet are included 4. Bone- by Dr. Wollaston, all calculi which are composed chiefly of Jj[J ra' phosphate of lime. This kind may be considered, perhaps, as corresponding with the 8th species in Fourcroy and Vauquelin's arrangement. These calculi are soluble in hy- drochloric acid. 9. By comparing the composition of urinary calculi with AU tf.ejn- that of urine, it will be found, that all the ingredients ot*fcalculi these concretions are present in this animal liquid, except are found^ oxalate of lime, phosphate of iron, and cistic oxide. lneceplox»_ phosphate of iron is given on the authority of a single ana- late of lime, lysis, and is certainly an ingredient in calculi of very rare pho^ate occurrence. Too little is known of the manner in which the cistic „xide. constituents of cistic oxide are combined, to allovv of a con- jecture to be formed of the probable source of this peculiar substance. The oxalic acid found in calculi is probably formed from uric acid; for Brugnatelli has observed, that oxalic acid is instantaneously formed, when chlorine is pas- sed through water holding uric acid in solution. 10. As to the manner in which urinary calculi originate, it may be remarked, that, as far as observation his gone it would appear that uric acid is formed in the kidneys. 1 he cqq ANALYSIS OF MORBID PRODUCTS. Part il calculous granules, emitted by persons labouring under ne- Book HI. phritic complaints, are found to consist of this acid. It is, therefore, probable, that uric calculi are not formed origi- nally in the bladder; but, by descending from the kidneys yet of small size, become the nucleus of a future calculus in that viscus. Calculi may 11. Fourcroy and Vauquelin have made a number of ex- be dissol- periments, in order to ascertain how far it would be practi- 'ht'body. cable to dissolve urinary calculi, by injecting solvents sy solutions through the urethra. As far as solvents are concerned, these bas^so^of concretions may be arranged under three heads: 1. Calculi acids, so composed of uric acid or of urate of ammonia; 2. Those be^eidVn composed of the phosphates; and 3. Those composed of the mouth oxalate of lime. Solutions of pure potash or soda, so weak witheutin- as that they may be held in the mouth without inconveni- ence*111" ence and swallowed yvithout pain, dissolve readily calculi of the first kind. Nitric or hydrochloric acid, so much di- luted as to cause no inconvenience when swallowed, dis- solves very quickly calculi of the second kind. The third kind are of more difficult solution. Such calculi, however, dissolve slowly in nitric acid, and in solutions of the carbon- ates of potash or of soda, so much diluted as not to irritate the bladder. These sol- 12. It is proposed by these chemists to inject the solvent, vents, pro- at the blood heat, into the bladder, previously emptied of ?nje?ted°in? urine. In order to ascertain the proper solvent, they propo- to the blad- setl nrst to inject a weak solution of potash, the solvent pro- der# per for calculi of the most frequent occurrence. After the injection has remained for half an hour or longer, it is to be discharged, filtered, and tested by means of hydrochlo- ric acid. If any uric acid has been dissolved, it will be thrown down by this test in the form of a white powder. If no indication of the presence of uric acid exists, and that after the solution of potash has been used for several days; it is next proper to proceed as if the stone present was com- posed of the phosphates, and accordingly to inject hydro- chloric acid, diluted to the proper degree. Should the stone prove to be composed of the phosphates, then by testing the solvent, after being returned from the bladder, by am- monia, phosphate of lime will precipitate. If this should not be the case, the last resort is to proceed in the manner proper for the mulberry calculus, and inject a properly di- luted nitric acid. In case any of the solvents succeed for some time and afterwards cease to have effect, they should be changed for others, until the proper solvent may be hit upon, to suit the chemical nature of the particular coat of the concretion which may present exteriorly. GOUTY CALCULI. 581 Chap. II. SECTION VII. ------ OF GOUTY CALCULL 1. It is well known, that certain concretions are formed Gouty eai- in the joints of persons long subject to the gout, which, J^,.*™^ from their white colour and softness, are generally called soda. chalk stones. These concretions were first analyzed in 1797 by Dr. Wollaston, who found them composed of urate of soda. Having thus finished the consideration of all the parts and products of the human body, which have been observed with any degree of accuracy; it may conduce to give a cor- rect comparative idea of their chemical nature, to present a synoptical view of their constituents. Such a view is at- tempted to be given in the annexed table. A. Extractive is excluded from the enumeration of the in- gredients of muscle and marrow, as not being sufficient- ly characterized. B. The true skin is composed of gelatin, and the cuticle of modified albumen. C. The reader will recollect, that chyle contains a substance, considered as intermediate between albumen and fiXrin. D. To understand the ultimate constituents of blood as given in the table, it is necessary to recollect, that phos- phorus, calcium, magnesium and iron arc considered as constituents of the colouring matter of this liquid. E. The colouring matter of the blood is not, strictly spf-ak- ing, an ingredient in the lens, but a matter having all the properties of this substance, except colour: see page 556. F. It is the curdy part of milk which is considered as al- bumen, although somewhat different in its properties. The analysis of milk given in the table is to be consider- ed as of cows' milk. G. Pus, strictly speaking, does not contain albumen, but is made up principally of a substance, a good deal allied to albumen in properties. H. If Chevreul's opinion should prove to be correct, then adipocire is not a constituent in gall-stones; but the substance, taken for adipocire, is a peculiar one, yvhich Chevreul proposes to call cholesterine. TABULAR VIEW OF THE PROXIMATE AND ULTIMATE CONSTITUENTS OF ANIMAL SUBSTANCES. ANIMAL PARTS AND PRODUCTS. PROXIMATE CONSTITUENTS. ULTIMATE CONSTITUENTS. a •s .2 o \ a 41 a 3 JS < c "S JS 1 JS <+* O u s p 3 '£ V L-"3 o .2* '■3 < et u t. V ■o o o '■3 3 1 3 5n 3 00 4> o I JS 3 en 5 09 3 u o JS e. to O J3 CU c 3 jii. "5 4) « •u o ■J} 4> a .2 u B SB a a 53 c 0 •c 41 H3 o 4) 09 41 C so 3 a a '»* 0 a 3 a a a. "3 4) ■a 'C o 3 a 3 1 .3 "o 4) T3 'E o j= U ■3 a ■a '3 a 0 'a 0 JS a W ■a '0 ct 0 '0 s a 4> » '0 a 0 3 a .2 5 a a a 0 i) a JS 0 a u ■c p-. S .2 'c 0 a a a "o 4) a O .2 s a a a "8 4) a 0 a -3 .3 a 0 u-0 4. ■m a .5 "3 CO j£ a 0 Q. •■*. 0 4) a e 0 X> a O JS a 5. <*« 0 4> +-> a "5. 0 .c 0. i 0 c-0 41 3 4) O < a 0 09 "S 4) a J3 _Q. "3 SO a ■0 8 "3 4) a u eg -a 0 ■i 4) es c 0 •e a O a -o 0 — 0 4) a "3. s -c Ph a TO 8 "3 4) a 4> a "o 4> a J= O. ■3 CO 4» 3 a 4> e. 0 ■s a 4) a 0 41 a JS & 0 -c a. P 4) 6 4) a "3 X! 0 4) a 0 a a 3 oa 0 1. -a t-. 33 s .2 4> C be a 0 4> a ^= O. o> 0 J= EL s 'c 0 a a a •i c a .2 41 c so ffl S "0 41 a j= & O j: S- 3 O I-0 4) a •a 2 c t. _!-"S 41 a a c 4) SO 4) e JS 4) a •c a 3 J. 4) 0 c 41 s >-, e 0 JS i. a 0 3 5 ■a j3 2- u a JS 3 ■Jl 3 s 0 so Calcium. Magnesium. Silicum. iron. Manganese. Bone. p P S s s s 0 0 0 0 0 0 0 0J0 | Nail. P T — 0 0 0 0 0 0 Muscle. A — s — p — s S S s S — — 0 0 0 0 0 0 0 (>l 4 Skin. B p p 0 0 0 0 1 Membrane and Tendon. p 0 0 0 0 Cartilage and Ligament. S p T T 0 0 0 0 Brain. S p p s p p — P P s S 8 S T T 0 0 0 0 G 0 0 0 1 j | Marrow. A T 0 0 0 0 0 0" j | ! Hair. P s s T T T T T T T 0 0 0 0 0 0 0 0 0 j I 0 Chyle. C - P S T S S 0 0 0 0 0 0 0 0 i 1 < Blood. D p s p S s •S s S s 0 0 0 0 0 0 0 0 0 0 | | f! ■ ; - Feces. "I |: ■ 1 i s s P S s T ' T |T T T S 0 0 0 i 0 0 0 0 0 ! ! : Saliva. — p s p P p s 0 0 0 0 0 0 0 0 Gastric Secretion. s P 0 0 0 0 0 0 0 0 0 •0 0 Bile. s P s s T s s ■ T Tears. s p s s s S 0 0 0 (j 0 0 0 0 1 Mucus of the Nose. s p p s S s T s 0 0 0 0 0 (J 0 0 0 0 0 0 0 0 0 Cerumen. p P s s 0 0 1 Aqueous and Vit. Humours. T p s T T 0 0 ol oj oj | | 0 0 TT Crystalline Lens. E p s T T 0 0 » 0 (J 00 o| 1 Liquor of the Pericardium. p s p s — 0 0 0 0 0 0 Sinovia. P p p s S s 0 0 0 0 0 0 0 0 1 1 Urine. s s s P T p T S s s s s s S S S s s s s T s 0 0 0 0 0 0 0 0 0 0 000 | Sweat. s P p s 0 0 0 0 Semen. p p S s 0 0 0 0 0 c 0 Milk. F s P P p S s S s s s T 0 0 0 0 0 0 c 0 0 0 Liquor of the Amnios. s p s s S s • 0 0 0 (J 0 0 c 0 Pus. G p <( 0 c 0 Expectorated Matter. p s P I 0 0 c 0 ( 1 Liquor of Dropsy. s p s p T s 0 0 0 0 0 c 1 0 Liquor of Blisters. p p s s s i 0 0 0 0 0 0 t ) 0 Gall-stones. H s P P • j 0 0 0 0 Urinary Concretions. s S S s S p s p p I P S 0 0 0 0 0 0 0 0 0 0 Gouty Concretions. 1 P i 0 0 0 0 c ....."1 N.B. In the above Table, P stands for principal ingredient, S for secondary ingredient, and T for trace. The cypher indicates the presence merely of the substance at the head of the column, in which it is placed. For the notes belonging to the alphabetical references, see page, facing the back of the Table. [TofacenagedS.i.] • CHEMICAL CONSTITUTION OF THE HUMAN BODY. 583 Chap. III. CHAPTER III. REFLECTIONS UPON THE CHEMICAL CONSTITUTION OF THE HUMAN BODY. 1. By the assistance of the table just given, the reader will be enabled to enter into a general examination of hu- man animal constituents. 2. Bv far the greater part of the matter which composes Chief parts the human body may be referred to the general heads of jj^jjj1* bone, of muscle, of membrane, tendon, cartilage and liga- muscle,' ment, of fat, and of blood. It is evident, therefore, that ^f™g™d gelatin, albumen, fibrin, oil, and phosphate of lime are the fat&h[^: proximate constituents of the human body, which compose henceiu^ nearly the whole of its substance, whether solid, soft or li-mate con- quid. Gt latin occurs in bone, though not in large amount; stituents it constitutes the whole of membrane and tendon, and forms JU^e'™' a part of cartilage and ligament. Albumen enters largely fibrin, oil, into the composition of bone, of cartilage and ligament, and J^1^' of blood: it occurs in small amount in muscle, while it is ume. absent in membrane and tendon. Fibrin is the characteristic ingredient of muscle and of blood; and is no where else to be found, unhss the fibrous matter, detected in sinovia by Margueron, be considered as this substance. Muscle and blood are so verv analogous in constituents, as to justify the remark, so frequently made, that muscle is nothing else than solid blood. Oil exists in bone, and composes the whole of the adipose membrane; but is absent in the other principal parts of the animal structure. Phosphate of lime, as a characteristic ingredient, is peculiar to bone. 3. Besides being present in some of the principal parts of the human body already mentioned, gelatin, somewhat modified, forms the whole of the true skin, and a part ol marrow and hair; while it occurs in small quantity in sweat and in urine, according to some experiments. 4. Albumen constitutes a very important ingredient in most of the subordinate parts of the body. Somewhat mo- dified, it constitutes the whole of nail and of cuticle, and apart of brain, of marrow, of hair, of chyle of feces, of saliva, of bile, of the mucus of the nose of the cerumen of the ear, of sinovia, of urine, of milk in the form of curd, of all the serous liquids, and of pus. 5. Fibrin must be considered as peculiar to muscle and fa™^ to blood. . . . . muscle and 6. Colouring matter of the blood is certainly a very sm- blood. gular animal constituent; more especially if Berzelius s 584 CHEMICAL CONSTITUTION OF THE HUMAN BODY Paut ii. opinion shoald prove to be correct, that ph^phorus, cal- Bo"K UI- cium, magnesium, and iron are constituents in it, in no par- ticular state of combination. As to what composes the great bulk of this animal substance, there is some discrepancy of opinion. The most probable supposition perhaps is, that it is some modification of fibrin. The singular substance ana- logous to the colouring matter of the blood, found by Ber- zelius in the crystalline lens, requires further investigation. 7. It would be of considerable importance to ascertain the exact differences between vegetable and animal mucus. If they are really distinct substances, to avoid confusion they should have different names. Chemists have distinguished a vegetable and an animal jelly, a vegetable and an animal extrac ive, a vegetable and an animal fibrin. A solution of vegetable jelly is called gelatinous, as well as a solution of animal jelly or gelatin. This yvant of precision leads to error. Extractive is a very indefinite term, and means dif- ferent things as used by different chemists. The term mu- — ■ cilage is frequently employed without precision; it some- times means a solution of gum, and sometimes a solution of mucus. The solution of the latter might be distinguished by the adjective mucous. 8. It may be considered as very doubtful whether the peculiar nature of osmazome has been established. Picromel is 9. Picromel may be considered as the characteristic in- charactens-orre(ijent jn \y\\Ct [t enters into the constitution of gall-stones. tie of bile. ° , , • r t e mi It composes also a very large portion ot the feces. 1 he opi- nion of the excrementitious nature of the bile is not with- out support from the latter fact. 10. Certain gall-stones have been considered as composed entirely of adipocire. This opinion has been lately called in question by Chevreul, who considers that the gall-stones, previously supposed to consist of this substance, are in fact made up of a form of matter not previously recognized, which he proposes to call cholesterine. Ureabcha- 11. Urea is the characteristic ingredient of urine. This, racteristic secretion is very little else than a solution of urea in water. This animal substance is occasionally found as a constitu- ent of urinary concretions. 12. Cistic oxide is a peculiar animal substance, which occurs as a very rare ingredient in urinary concretions. Sugar of 13. Sugar of milk was first discovered in milk. Its dis- miik, found covery in chyle strengthens the analogy observed between well as hf* these animal liquids, which have a number of other consti- miik. tuents in common. A portion of iron is detected in both. 14. Oily substances, varying considerably in nature, are to be found in the various parts and products of the body. Be- CHEMICAL CONSTITUTION OF THE HUMAN BODY. 585 Bides the fixed oil, which constitutes the fat so universally Chap, lir found, filling up interstices and giving an uniform figure to the body and limbs, there are oils peculiar to particular parts. Marrow, according to Berzelius,contains a peculiar fixed oil. Human milk contains a peculiar oil, which, hoyv- ever, is not concrete, as that yvhich may be extracted from cows' milk. Brain and hair are found to contain peculiar coloured oils. Cerumen contains a peculiar oil, and so also does sweat. Bone possesses an oily part, yvhich is not strict- ly speaking a part of the bone. 15. According to Vauquelin's analysis of brain, phosphorus Phosphorus enters into it as a constituent. It is difficult to understand, "J^s. 'annd how such a substance could be present, without entering into some particular combination. 16. Uncombined sulphur has been detected as a consti- ""COI?bi|li'r tuent in brain, in hair, and in urine. It may be worthy of j^JMj,1" inquiry, whether the sulphur, detected in these substances, hah- and is derived from the albumen, which is one of their consti- uru,e- tuents. It is certain, that albumen cannot be obtained entire- ly free from sulphur: but, hov/ far this fact may prove Ber- zelius to be correct in asserting, that sulphur is an essen- tial ingredient in albumen, remains yet to be demonstrated. However this may be, it is certain, that uncombined sulphur has not. been detected in any animal substance, in which albumen has not been found. Phosphorus and sulphur are the only undecompounded substances, in an uncombined state, yvhich occur in animal bodies. Hence they are enu- merated in the table, both as proximate and as ultimate constituents. 17. Water must be considered as a very important con-Water, a stituent of animal bodies. It causes the liquidity of all those ^n «*p°£ parts of animals, which require to have this state, in order constituent. to answer the purposes for which they are intended. It is the only menstruum employed by nature. It must not, how- ever, be considered as unimportant in itself; as it consists ol two principles, as universally present in animal matter as any others. It may, therefore, be considered as very mate- rially concerned in nutrition. . . . J. Soda is an ingredient in bone, m blood, ,n feces m a*^_ saliva in bile, in tears, in the mucus ot the nose, in ceru- umber rf men, in the aqueous and vitreous humours of' «h<, «£ and— sub- in sinovia. The portion .of this alkaline base, which ex- lS„b and blood, is very small. That found in feces mav oe considered as derived from the bile. It occurs ,„ tears on account perhaps of its detergent property. The mucus "fTheXoseVobably derives its soda from the tears, which are con.nu.dv passing into this cavity. It may be pro- A K 586 CHEMICAL CONSTITUTION OF THE HUMAN BODY. PaktII. per to remark here, that Dr. Pearson, contrary to the re- Bqok ill. cejvej opinion, considers potash, and not soda, to be the al- kaline base present in the animal fluids. 19. Uncombined lime occurs in bone, in bile, and in the liquor of dropsy; but in very minute quantity in each. This ingredient cannot be considered of importance in animal sub- stances. 20. Uncombined magnesia occurs as a constituent in one class only of the animal substances, mentioned in the table; namely, urinary concretions. But one calculus has been found heretofore to contain uncombined magnesia. 21. Silica has been found in three animal substances only; namely, hair, urine, and urinary concretions. It occurs in very minute proportion in hair and urine. In concretions of the bladder, it is a rare ingredient. Iron, de- 22. Traces of uncombined iron, or of oxidized iron, have tected m Deen detected in chyle. The same metal, together yvith man- chvic iron * * o and manga- ganese, has been detected in hair. nese, in 23. Chloride of potassium occurs, in small amount, in Chloride of blood, in saliva, in the mucus of the nose, in the aqueous and potassium vitreous humours, in the crystalline lens, and in milk; but un? hfwhat wnetner as an essential ingredient, and in an invariable pro- animal sub- portion, has not been correctly ascertained. Chloride of so- stancespre- dium occurs in muscle, in hair, in chyle, in blood, in saliva, in the gastric secretion, in bile, in tears, in the mucus of the nose, in the aqueous and vitreous humours, in the crystal- line lens, in the liquor of the pericardium, in sinovia, in urine, in the liquor of the amnios, in the liquor of dropsy, and in the liquor of blisters. Thus it appears, that this chlo- ride is present in every animal substance, in which the chlo- ride of potassium is found, except milk; and in a great num- ber of substances, in which it exists alone. This very gene- ral occurrence of chloride of sodium, in small proportion in the animal fluids, favours the belief, that this chloride is rather an accidental than an essential constituent, more es- pecially as it is introduced, into the stomach, so universally yvith the food. Uric acid, a 24. Uric acid occurs in small amount in urine, where urea chief mgre-js abundant; but as a very principal ingredient in urinary culi; but a concretions, in which urea is a rare ingredient. It has con- subordinate siderable analogy to urea in some of its properties; and the inverse proportion, in which these tyvo substances occur in urine and in urinary calculi, favours the opinion, that urea is convertible into uric acid, and by undergoing this conver- sion gives rise to the formation of uric calculi. Besides uric acid, several other uncombined acids are present in ani- mal substances; as carbonic acid in bone, urine, and syveat; one in urine. CHEMICAL CONSTITUTION OF THE HUMAN BODY. 587 benzoic acid in urine only; and lactic acid in urine, sweat, Chap, ni. and milk. 25. Of salts, hydrochlorate (muriate) of ammonia occurs Salts pre- in urine and in urinary calculi, and no where else; phos- "jjl™"1' phate of ammonia, in brain and in urine; lactate of ammonia stances. and the sulphates of potash and of soda, in urine only; car- bonate of potash, in expectorated matter; phosphate and ace- tate of potash, in milk only; urate of soda, as peculiar to gouty concretions; and carbonate of soda, in semen, in the liquor of the amnios, and in the liquor of blisters. The phos- phate of soda occurs more generally distributed than any of the salts just named. It is found in muscle, in brain, in blood, in bile, in tears, in the mucus of the nose, and in urine. Lactate of soda occurs in muscle, in blood, in saliva, and in the mucus of the nose. Traces of sulphate of lime have been detected in brain and in hair, but in no other ani- mal substances; and of carbonate of lime, in hair and the li- quor of the amnios. Phosphate of lime has already been Phosphate mentioned as constituting the basis of bone. It occurs also in °n"rmcet'eris. nail, in muscle, in brain, in hair, in chyle, in bile, in tears, in tic of bone. cerumen, in sinovia, in urine, in semen, in milk, in the liquor of the amnios, in the liquor of blisters, and as a common in- gredient in urinary concretions. Thus this salt, besides forming the greater part of bone is found distributed, in small quantity, in many animal substances both solid and liquid. Oxalate of lime occurs as an ingredient of urinary Oxalate ot calculi only. Hydrofluate (fluate) of lime is found as a con- »J™ ^d. stituent in bone, and, in very minute proportion, in urine. narycalcu- Phosphate of magnesia is present in bone, in urine, and in''. milk; while the ammonio-phosphate is found only in urinary concretions. Oxidized iron has been found in the state of phosphate in a calculus, and in the state of lactate in milk. 26. The uncombined acids have been noticed already, as Acids found being the uric, carbonic, benzoic and lactic acids. All these |^™n».* acids, except the benzoic, occur also in saline combinations, ed or otter- Besides these acids, there are found, always in a combined re- state, the hydrochloric, sulphuric, phosphoric, oxalic, acetic, and hydrofluoric (fluoric) acids: so that the total number of acids found in animal substances is ten. Uric acid is found combined only with soda, in the form of gouty con- cretions; carbonic acid, only with potash, soda and lime; lactic acid, with ammonia, soda and oxidized iron. Uric and lactic acids are exclusively of animal origin. Hydrochlo- ric acid is found combined with ammonia only; sulphuric acid with potash, soda and lime. Phosphoric acid exists combined with ammonia, potash, soda, magnesia, oxidized iron most but particularly with lime. This acid is by far the Phosphori [ abundant in animal substances. The oxalic acid oc-**-» mos' 588 ANIMAL FUNCTION'S ELUCIDATED BY CHEMISTRY. Pa»' II. curs in combination with lime, only in certain species of I*""" '** urinary calculi. The acetic acid combined with potash has ab-ixiantiy been detected in milk by Berzelius alone. The hydrofluoric present ot (fluoric) acid is a very rare constituent in animal substan- nnimais! cesi and is always combined yvith lime. Lime, the 2'r* Of the alkaline salifiable bases, lime is beyond all most i.imn- comparison the most abundant in animal substances. Next We brwe,fia'to n comes soda, then potash, then magnesia, and lastly am- monia, the three latter being in very small amount. The only earthy base heretofore detected in animal substances is silica, and that in very small proportion. Oxygen, a- 28. As the ultimate constituents of animal substances, it zote, hy- js perceived by the table, that oxvgen, azote, hydrogen and cIr>Son the carDon comprise nearly their whole amount. Phosphorus and most abun- calcium are the next most abundant, being ultimate consti- matVc11"- tuents °f Done* Chlorine occurs in combination with potas- stituents. sium and sodium; and combined with hydrogen forming hydrochloric acid. This supporter is present in small amount in nearly tyvo-thirds of all animal substances. Flu- orine is given in the table, on the supposition, that the radi- cal of the hydrofluoric (fluoric) acid will prove to be some neyv form of matter. Sulphur, as an ultimate constituent, occurs, in minute quantities only, in animal substances. Po- tassium, sodium, magnesium and silicum occur nearly in the same relative proportions as potash, soda, magnesia, and silica, of which they are the radicals. Excepting the alkaline and earthy metals, iron and manganese are the on- ly metallic bodies found in animals. Now it will be recol- lected, that these same metals alone were detected in vege- tables. It can hardly be supposed possible, that animals could contain a constituent, which did not exist in vegeta- bles; as the former, either directly or indirectly, draw all their nutritive materials from the latter. CHAPTER IV. OF ANIMAL FUNCTIONS ELUCIDATED BY CHEMISTRY. A great deal of interesting matter might be arranged under this title; but the proposed limits of the present work will or.-ly permit of giving a sketch of what is known on respiration, and some reflections on secretion and assimila- tion RESPIRATION. 589 Chap. IV. SECTION I. OF RESPIRATION. 1. All animals are furnished with some contrivance or All animals other for exposing their blood to the influence of the air. B?hiec}, _, t-,,. i • i- i i rt • i their blood 1 his remark is applicable to fish, to insects and to worms, to the ac- as well as to the more perfect animals. tion of air. 2. The contrivance, in man and in the warm blooded ani- Mechanism mals, consists in a cavity, capable of being increased in size °.f re*P,ra: by the action of muscles, and containing vascular bags, called bed. the lungs. These bags are so arranged, as that the commu- nication of the external air, with the cavity, must take place through apertures in them, and in no other way. It conse- quently happens, that when the cavity is enlarged by mus- cular action, the external air presses into the bags; but when it is rendered smaller, the contained air is pressed out; and it is on this mechanical principle, that breathing is carried on. 3. What purpose, then, does this exposure of the blood In respira- to the influence of atmospheric air effect? This question can ^°V^ air be answered only by investigating the changes, which are and the consequent to it, upon the respired air and the blood; and k'0**5 j^1" accordingly these objects of research have engaged the at-° tention of numerous chemists and physiologists. 4. Common air, which has been respired, is altered in the following particulars: a portion of oxygen has disap- peared, a quantity of carbonic acid has been formed, and it is loaded with water in a state of vapour. 5. Taking the general results of experimenters on the subject, it will be found, that the bulk of the carbonic acid, formed during respiration, is very nearly, if not precisely, equal to that of the oxygen which has disappeared. Now it is well knoyvn, that oxygen, when ohanged into carbonic acid, does not alter its bulk; hence the presumption is, that the whole of the oxygen, yvhich disappears as uncombined oxygen, enters into the composition of the carbonic acid emitted. This is a more probable opinion than the one which supposes, that the oxygen yvhich disappears has com- bined permanently with the blood, and that the carbonic acid evolved had previously existed in this animal liquid ready formed. 6. In this way, tyvo of the changes which take place in air by respiration, namely the disappearance of uncombined ox> gen and the evolution of carbonic acid, are explained. It is only uncombined oxygen yvhich has disappeared; for the oxygen, in the combined state, is still present in the car- bonic acid formed. From this it is evident, that air in re- 590 ANIMAL FUNCTIONS ELUCIDATED BY CHF.MIsTRV Part ii. spiration loses nothing, but gains a quantity of carbon; and jjook in. tms carbon is separated from the blood. The fair conclusion Reip-.-smn therefore is, that the principal intention of respiration is to carbon16' eliminate carbon from the blood. from the 7. The third alteration, which takes place, in respired air, blood. js jts being loaded yvith vapour. This vapour cannot be con- sidered as formed in the lungs, as is the case with the car- bonic acid; since all the oxygen which disappears goes to the formation of this acid. It is, therefore, probable, that water is given out by the vessels of the lungs, and becomes dissolved in the respired air on account of its increase of temperature. 8. The quantity of carbonic acid, emitted by the lungs, is found to vary at different times in the 24 hours. It has been ascertained by Dr. Prout, that the quantity of this acid formed is greatest at noon and least at midnight. Average 9. Several calculations have been made to ascertain the quantity probable quantity of carbonic acid emitted by respiration in ot carbon t^e 24 hours. Dr. Thomson considers the average to be emitter is .... . . . , ° . three- 40,000 cubic inches, a quantity which contains about three- fourths of a quarters of a pound avoirdupois of solid carbon; and this hours.m estimation does not differ much from that made by Allen and Pepys, as deduced from their experiments. Under par- ticular circumstances, however, the usual quantity of car- bonic acid formed is lessened. Thus it has been ascertained . by Dr. Prout and Dr. A. Fyfe, that the carbonic acid, pro- duced by respiration, is diminished by the use of spirituous and fermented liquors, by the action of mercury or of ni- tric acid, and by a vegetable diet. 10. The amount of aqueous vapour, emitted in the twenty- four hours, is no doubt exceedingly various in different in- dividuals, and under different circumstances. From some trials to ascertain this point, made upon himself, Dr. Thom- son found, that nearly nineteen ounces was the quantity emitted by his lungs for that space of time. Arterial 11 • It nad been observed at a very early period by ph\ - diffeisinco-siologists, that the blood, which flows in the veins, is differ- ▼enous°m ent *n appearance from that contained in the arteries. Ve- blood. nous blood has a dark purple colour, while arterial blood is of a bright scarlet. Now it is well known, that blood in the venous state is returned, from all parts of the body, into the heart, on its right side, whence it passes into the lungs by the ramifications of the pulmonary artery, and is ultimately received again into this organ, on its left side, from the pul- monary veins. But by the time it has arrived on this side, it is no longer of a dark colour, but has assumed a bright scarlet one, and the arterial character. It therefore appears, RESPIRATION. 59 \ that this change in blood takes place exclusively in the Cuap.IV. lungs; and it is fair to conclude, that it depends entirely :$^~£. upon the influence of air in respiration. This influence has comes arte- already been stated to consist in the separation of carbon. jJthe1 u»*s 12. An absolute chemical difference has never been by being de- made out, by experiment, between arterial and venous carbonized. blood; but it is fairly inferable from the facts, just stated. How then, it may be asked, does arterial blood acquire a redundancy of carbon, whereby it becomes changed into ve- nous blood? To this it may be answered, that the redundan- Probable cy propably occurs, in the course of the circulation, in con-causeofre' sequence of the abstraction, in secretory processes, of a0fcarbon in larger proportional quantity of all the constituents of blood venous except carbon, than of the carbon itself. Whether this con- ge°s°e(i!US" jecture be well founded, could only be ascertained by noti- cing, if all the constituents of blood, except carbon, be pre- sent in larger amount in the secretions, taken collectively, than carbon itself. 13. Respiration has as yet been considered as carried on Atmosphe- by atmospheric air, the only gaseous fluid which supports •«»•''• the the process properly; but, besides this fluid, there are seve- ™maintain rai other prases, which may be respired, but which sooner or the respira- 1 .. j .. it toiyfunc- later destroy life. tion; others 14. One set of these respirable gases, which do not sup- are respira- port life, seem to act negatively, by depriving an animal of j^'J^"* uU the air, proper to carry on natural respiration. In this yvay destroy life. azote and hydrogen are supposed to destroy life. Another set of respirable gases appear to be unfit for respiration, in consequence of some positive effect which they produce on the blood. In this yvay, the bihydroguret of carbon (carbu- retted hydrogen), hydrosulphuric acid (sulphuretted hydro- gen), and carbonic oxide are supposed to act. A third set may be breathed for some time, yvithout much inconvenience, but would unquestionably sooner or later produce death. Of this kind are the protoxide of azote (nitrous oxide), and oxy- gen gas. These gases yvould appear to be improper for sup- porting life, on account of the too great stimulus, yvhich they produce. The protoxide of azote is known to give rise to a very strong degree of stimulation, and oxygen gas appears to require some other gas to be mixed with it, for the pur- pose of dilution. Common air, which is the only proper ga- seous fluid for respiration, may be considered as oxygen gas diluted by azote. Oxygen, diluted by hydrogen to the same degree, carries on respiration without inconvenience; and the formation of carbonic acid goes on as regularly as when common air is the respired fluid. There are, however, these differences when oxygen and hydrogen are employed, that 592 ANIMAL FUNCTIONS ELUCIDATED BY CHEMISTRY. Part II. Book HI Certain ga- ses cannot be drawn into the lungs. Effects of different gasi 3 on ve- nous blood. Effects of different gases on arterial blood. Animal heat, attri- buted to respiration Crawford's theory of animal heat is founded up. a portion of the oxygen disappears, and azote is found in its place, and the animal, breathing the mixture, has a ten- dency to sleep. 15. Some gases cannot be drawn into the lungs, the glottis closing spasmodically whenever the attempt is made. These have been called unrespirable gases. To this set belong am- moniacal gas, carbonic acid gas, and in short all the acid gases. 16. It has already been stated, that venous blood becomes arterial, by passing through the lungs. Now it has been as- certained, that venous blood, out of the body, assumes the colour of arterial blood, yvhen exposed to some of the g.ises. Venous blood, subjected to the influence of pure oxygen gas confined over it, instantly assumes a scarlet colour. The same change in this kind of blood is effected by common air, but not so rapidly. In both cases, the bulk of the air re- mains very nearly, if not absolutely, the same; but the air itself is changed, a portion of its oxygen being converted into carbonic acid. Hence it yvould appear, that the same changes take place in venous blood, when exposed to com- mon air or oxygen gas, out of the body, as yvhen in the lungs. 17. Venous blood, exposed to the action of deutoxide of azote (nitrous gas), becomes of a deep purple colour. Un- der similar circumstances, the protoxide of azote (nitrous oxide) changes its colour to a bright purple. In both cases, a portion of the gases is absorbed. When exposed to the action of carbonic acid, it becomes much darker, and a small portion of the gas is absorbed. Bihydroguret of carbon changes it to a fine red colour, a shade deeper than that pro- duced by oxygen gas. 18. On the other hand, arterial blood, exposed to the ac- tion of azote, hydrogen or carbonic acid confined over itr assumes the colour of venous blood. This same change takes place in it, however, yvhen placed in vacuo. Hence it must be considered as independent of the action of any external agent. This change, in arterial blood, is not pre- vented even by exposure to the action of oxygen gas, although it is very considerably retarded. 19. Animal heat is usually attributed, as an effect, to re- spiration, although there are many circumstances unfavour- able to this opinion. The fact, however, is a striking one, that the heat of different animals is greater, in proportion as their apparatus for breathing is on a larger scale. 20. By far the most ingenious theory of animal heat, de- duced from the respiratory process, is that of Dr. Cravv- ford. Dr. Black had considered, that animal heat is pro- duced in the lungs, in consequence of the conversion of RESPIRATION. 595 latent into sensible heat. Upon such a supposition, hoyvever, Cbap.IV. the heat could not be uniform all over th body. Dr. Cra*.\-on a difTer- ford gets over this difficulty, bv supposing, that part of the ence in the heat of the respired air becomes latent in the blood, after it heatof ar- has assumed the arterial character. This transler, he consi- tem.1 and ders to take place, in consequence of a simultaneous alteration J^™8 in the specific caloric of the air of respiration and of the blood; that of the air being decreased, while that of the blood is proportionably increased. In this way, the caloric, derived from the air, and which yvould otherwise have been sensible or distributable, is instantly transferred to the blood, to fill up its increased capacity. Now Dr. Crawford found, that the specific caloric cf oxygen gas and arterial blood on the one hand, was greater than that of carbonic acid and venous blood on the other; just what ought to be the case, if the theory which he advocated were correct. Hence it must follow, that, in the course of the circulation, as the arterial blood is gradually assuming the venous character, in consequence'of those actions which are implied in the functions of secretion and nutrition, it is at the same time suffering a decrease in specific caloric or capacity, and must be, in the same proportion, evolving distributable heat. 21. Although subsequent experiments have confirmed This differ the conclusions of the difference in specific caloric of car -^^ bonic acid and oxvgen gas, and of venous and arterial Crawford blood; yet they are far from making it as great as was cal- supposed. cuiated by Crawford. From the experiments of Delaroche and Berard, it appears, that the specific caloric of carbonic acid is to that of oxygen gas, as 0*8280 to 0-S848; while those of Dr. Davy determine the relative specific calorics of venous and arterial blood to be as 0*903 to 0*913. These differences are so small, that they would hardly be consi- dered as sufficient to account for all the animal heat on Crawford's theory; but, when it is recollected, that the whole of the blood of the body makes a compete revolu- tion in less than three minutes,* when the fact is adverted to that arterial blood is undergoing the change intbvenous blood in all parts of the body at the same moment, >hese differences in specific caloric may not perhaps be ^e,med too minute to account for the production of animal he:*. 22. It appears by some late expenments, pertormei byB*9 Brodie, tha , when respiration is carried on artificially™ a JJJ^ seem unfavoura- ble to the ■—---------- . . Bie 10 uie ^.. .i .„„ ^Fthc time which the whole of the blood of the body tr'~s supposition • Tim calculation of the me wh.ch ltl0ns, lhat the amount »thJtPl.e8 U to pass throug£ |J° h|J ^nX"that the average number of pulsaUons ,n a nu- ation c»us ££ is" 75 fnd th t'tne^uanti y of blood exiled at each pu.saUon „ two ar.d g^ a half ounces. ^ 594 ANIMAL FUNCTIONS ELUCIDATED BY CHEMISTRY Part II. decapitated animal, the usual proportion of carbonic acid Book ill. continues t0 De formed; and, notwithstanding, instead of the animal heat being preserved under such circumstances, it is actually lost quicker than it would be in an animal re- cently killed. To judge how far these results invalidate the conclusions of Crawford, it would be necessary to inquire, whether, in Brodie's experiments, the blood returned to the lungs in the arterial or venous state. If it returned in the ve- nous state, it would seem to prove, that the blood had under- gone those changes, which are consequent to its employment in secretion and nutrition; but it is not probable that it could be thus employed in a decapitated animal. But if it be sup- posed, that the blood, in such cases, undergoes little or no change in the course of the circulation, is not the loss of animal heat, just what ought to take place according to Crayvford's theory, which considers that the animal tempe- rature is kept up, as a consequence of the gradual conver- sion of arterial into venous blood. On the other hand, if the blood goes the round of the circulation without losing its arterial character, yvhence is the carbonic acid derived, which Brodie found to be invariably formed in his experi- ments. Respiration 23. Upon the whole, perhaps the most correct opinion is probably on the subiect of animal heat is to suppose, that the princi- the Drinci- *^ <* pal cause of pal cause of it is respiration, by effecting upon the blood animal such a change, as that, upon another change during the cir- aMtstedby8 culation, it will be giving out, gradually, distributable heat; other greatly assisted, however, by the vital actions, such as se- causes. cretion, digestion, muscular action, and, in short, by every process implying- r tion, which occurs in the living body. SECTION II. jECRETION AND ASSIMILATION. Fooduu- 1. -li'-rent parts of the animal system are constant- dergoes ly -, ;, ^ a yvaste, which is supplied by materials ta- ebangesbe-k ^ »^ stomach. These materials undergo a suite of fore it be- ( han/e<. .•■: the processes of digestion and chylification; and blood! '*'•-* F,u(ict *s tnrown mio tne blood vessels, where it be- et . «rfect blood. Into this complex liquid, all the nu- ;.•■•■ . matter, taken into the stomach, must be converted, Bir-.. - one particle of it can be employed to supply the exi- *r les of the living animal; for it is from blood alone, that ' .'. ] the parts of the body, yvhether solid or liquid, are jrmed. Now the action, by which certain liquids are sepa- SECRETION AND ASSIMILATION. 595 rated from the blood, is called secretion; and the action, Chap. IV. by which the same animal liquid is converted into the orga- nized parts of the body, is called assimilation. Blood being, then, the material from which all the parts of the body are formed, it follows, as a necessary consequence, that this li- quid must contain all the elementary principles of animal substances. 2. The secretory action takes place in the body, appa- Secretions rently with two views: 1. to form from the blood a sub- ^Ve^sed, stance to be applied to some useful purpose; and 2. to se- or to be parate something from the same liquid, which is either thrown off. noxious or useless, and which is to be thrown off from the body entirely. 3. All the secretions of the human body may be consi- Excremen- dered as formed with the first view; except that of urine in JJJJgJ,"^ the kidneys, of sweat by the skin, and, without perhaps re- urine, sorting to any very strained analogy, of carbon and water by **reba*nand the lungs. It may be considered doubtful, whether bile is se- creted with the first or second view; but the latter supposi- tion is the most probable. 4. Considering then the useful secretions, the question An *hceo°1Ji' arises, are the constituents of these substances to be found "t\auee„ts of in the blood. The answer is yes, so far as it regards the useful ultimate constitutents. Indeed most of their proximate ^tl0ns constituents are present in this liquid, but not all. Thus, blood, but mucus is present in saliva, tears, the mucus of the nose,££*£*•. the liquor of the pericardium, and in semen, but not in constitu- blood. Sugar of milk is present in chyle and in milk, but is cms. absent in blood. These facts are sufficient to demonstrate to the physiologist, that, during secretion, substances alrea- dy formed are not merely separated; but that the blood ac- tually suffers decompositions and recompositions in the process. ,. . 5. In the process of assimilation, a great many very dis- Aj^ similar organized substances are formed trom the blood. I he organized principal of these are muscle and bone. Blood contains, in parts. abundance, the substance, which is the characteristic ingredi- ent of muscle, namely fibrin; hence the formation of the latter from the former may be very well explained. But the prin- cipal ingredient in bone is phosphate of lime; how then does the blood furnish this salt, which does not exist ready form- ed in it. It is indeed true, that phosphoric acid exists in blood and so also does the radical of. lime according to Berzelius, as a constituent in its colouring matter. Accord- ingly it may be said, that the phosphate is composed in the -ict of forming or repairing the bone; or it may be contend- ed that its quantity in the blood, sufficient to renew the 596 ANIMAL FUNCTIONS ELUCIDATED BY CHEMISTRY. Part h. daily waste of bone, is too small to be detected in the mass B|1"- In of this liquid. ... Z 7~ 6. By viewing the table given of animal substances, it will STuli be seen, that blood contains all the ultimate constituents m,*t con- found in them eXcept fluorine, silicum and manganese. I he anSsut question, therefore, arises, how can blood form bone which ■tan«-s are contains fluorine, or hair which contains silicum and manga- rn°blLnd nese* Are these facts to warrant the conclusion, that neither fluorine, silicum, nor manganese are simple substances; or should thev not rather be explained by supposing, that these bodies exist in too minute quantities in the blood to be de- tected. . Blood re- 7. It is reasonable to suppose, that the blood, suffering quires, not so many abstractions of its constituents in secretion and only to be assimilation> WOuld require, not only to be renewed con- buaheVro. stantlv by new accessions of matter, but also to have thrown portions of off from jt particular constituents, yvhich might be left in Sto'lSiS: excess by a too abundant abstraction of others. And this, justed; and indeed, appears to be the fact; and to separate such redun- Sstmenfis dant constituents, would appear to be the purpose of the effected several secretory actions, which eliminate substances to be E?£S£7 ^rown out of the body. tions of 8. The substances, which it is here proposed to consider waste- as secretions of waste, are carbon emitted from the lungs, Separation urine, sweat, and the bile. The process, by which carbon is e.be interrupted in its function, the lungs suffer. This is usually hence the accounted for by supposing, that the aqueous fluids, which sympathy should pass through the skin, are thrown upon the lungs; °ans,e6e but ma)' not the suspension of the separation of carbon through the skin, in cases of suppressed perspiration, be the 598 ANIMAL FUNCTIONS ELUCIDATED BY CHEMISTRY. Paht n. principal cause of the inconvenience, suffered by the pulmo- BooK lir- nary organs. It is well knoyvn, that the kidneys perform the vicarious office of the separation of aqueous fluid, when such fluid is prevented from passing through the skin; now, when carbon is retained as a consequence of suppressed per- spiration, does not the coincidence in office between the skin and the lungs make it probable, that these organs may excrete a superabundant quantity of this combustible, as long as the suppression by the skin may continue. It is a well known law, yvhich the Authorof nature has impressed upon the animal economy, that the different organs, like kind friends, assist each other in the performance of their respective functions, when, from disease or otherwise, any one of them may be unable to perform its own. Theinten- 13. Bile has been enumerated as a substance, which is se- tion of bile parated from the blood as useless; but this point is far from stul conti- f. . l l a _i • i ■ r.. . . . nuesdoubt- being settled. Adopting, however, the supposition that it is ful. separated for the sake of the blood, there are no circum- stances which lead to the belief, that it contains any particu- lar principle, yvhich it is the chief purpose of the liver to se- parate. Secretion 14. With regard to the manner in which secretion and iaUondo"11 assignation take place, very little or nothing is known. The not consist reader has had abundant proof, however, that the first is not in the sepa- the separation of something, already formed in the blood, or ration ot ., . * , . P . J , , * something the latter, a mere deposition; since, in innumerable cases, already compound substances are found in the secretions and in the the™6 fun". solid parts, not previously existing in the blood. Hence tions imply then chemical decompositions and recompositions must ne- action's*1 cessarily take place in these vital functions. 15. Notwithstanding these strong facts, there have not been wanting some physiologists, who have denied altoge- ther the agency of chemical attractions in the vital pro- cesses. According to them, chemistry, so far from assisting the animal functions, is in perfect war with life; and when the former has gained an ascendancy over the latter, destruction is the consequence. In proof of this assertion, the putrefac- tion of animal bodies, after death, is alleged. 16. To prove how fallacious this mode of reasoning is, let it be supposed for a moment, that those agencies of mat- ter upon matter, which are called chemical attractions, were annihilated; what would be the consequence? Most unques- tionably it would be impossible for any animal to live. 17. But although chemical actions do take place in animal processes, it does not follow that they are beyond the con- trol of other agencies; the fact is that they are not; and life, yvhatever it may be, whether dependent upon a peculiar SECRETION AND ASSIMILATION. 599 principle or upon organization, is the something which di- Cbap. IV. rects them. -------- 18. The agency, however, which directs the chemical vital agen- changes in animals, is not absolute in its power, but yields c780me" under extraordinary circumstances. Thus, if peculiar sub- JJlJeSe-" stances be taken into the stomach, they make their way into m»«l agen- the secretions, and even into the solids themselves. Musk cy" and indigo have been made to pass into some of the secre- tions, and the colouring matter of madder into the bone. Hence it would appear, that the digestive organs cannot convert every substance to the purposes of the animal; and that even when unusual substances get into the blood, they cannot always be excluded, by the secreting or assimilating powers, from entering into the composition of the solids and fluids. 19. In what manner the control over the ordinary che- Particles mical affinities is exercised in the living body, would be composing difficult to determine. It is not possible, that the particles obey*che- which compose animal bodies can enjoy any immunity from mical at- the influence of the chemical attractions. They cannot con-tractl0n'* stitute an exception to the universal lot of matter. If this po- sition be true, then the springs to chemical action cannot be considered as suspended, but the chemical actions themselves counteracted by opposing actions. Shall it be said, that it is life which is the counteracting force, or are there any agen- cies which exercise the same influence over chemical affini- ties out of the body? If there be, then certainly an identity of effect may be fairly ascribed to an identity of cause. Now it has been fully proved, that galvanic electricity has the power of counteracting the ordinary results of chemical af- finity; and may not the same agency be the proximate cause of a similar counteraction of chemical affinities in living bodies. 20. After all, even admitting the supposition just stated to be true, still this electrical agency must be under the con- trol of some other power; and this power may be denomina- ted life. 21. As soon as life leaves the body, the different chemi- cal affinities are no longer controlled, and its constituents form compounds totally distinct from its original component parts. A sketch of yvhat is known concerning the changes, which take place under such circumstances, will be given in the following chapter. 600 PUTREFACTION OF ANIMAL IJODIES. Part II. Book 111. ---- CHAPTER V. OP THE DECOMPOSITION OF ANIMAL BODIES AFTER DEATH. Dead ani- j. IT js a Wi>\\ known fact, that the matter composing ani- putrefies; mal bodies, which have ceased to be influenced by vitality, undergoes certain changes, accompanied by the emission of a disgusting fetor. These changes are expressed by the term putrefaction. 2. It does not, hoyvever, necessarily happen, that dead animal matter should putrefy. A certain complexity in its composition, by which is meant a mixture of a number of substances already compound, is a necessary pre-requisite to the putrefactive changes. Thus, animal substances, which are uniform compounds, such as oils and resins, do not pu- trefy. Besides this complexity, dead animal matter requires to be under the influence of heat and moisture, before it can take on the putrefactive process. This is proved by the cir- cumstance, that animal matter, exposed to a freezing tempe- rature, or perfectly dried, undergoes no change whatever. Exposure to air is not an indispensable pre-requisite; for the putrefactive changes take place in close vessels, although somewhat modified under such circumstances. 3. Animal matter, exposed to the predisposing circum- stances just stated, undergoes a suite of changes, of yvhich the following is an outline. If it be a portion of flesh, it first becomes pale and somewhat soft; its texture next begins to be destroyed, and it emits a disagreeable smell. The expo- sure being still continued, it diminishes in bulk, and exhales an ammoniacal odour. This smell is dissipated by the sur- rounding air, and is succeeded by the insupportable odour denominated the putrid smell. This continues for some time, but is at last restrained by the production of ammo- nia. This alkaline base has no sooner been dissipated, than the putrefactive process recommences, and the flesh swells up, emitting a number of air bubbles, and then subsides. At this stage of the decomposition, the fibrous texture of the flesh is scarcely distinguishable, and the whole becomes a soft mass of a brown or greenish appearance, and having a faint and nauseous smell. After this stage of the process, the odour is gradually lost, and the putrefied matter acquires some consistence and a deep colour. It is finally converted into a friable matter, which breaks into coarse powder, like earth, between the fingers. This substance consists of the fixed parts of the animal matter, mixed with some charcoal, oil, and ammonia. The gaseous products vary somewhat, according to the substance yyhich may be subjected to the ifcomplex in its na- ture, and sub- jected to certain de grees of heat and moisture. Putrefac tion de- scribed. PUTREFACTION OF ANIMAL BODIES. gQl putreiactive process; but they consist principally of hydro- Chap, v. gen gas, combined with sulphur phosphorus and carbon, of ammonia and carbonic acid gas, and perhaps of azote. Oc- casionally nitric acid appears to be formed. 4. Thus it would appear, that animal matter, after its It depends death, being no longer embarrassed by the operations of vi- uP°n * n*w tality, is influenced by a new play of chemical affinities, niues° & which causes irs ultimate constituents to enter into new and more simple modes of combination. 5. Putrefaction, as already described, must be taken as Putrefac- applying to dead animal matter, putrefying separately andt10" '* re" in contact yvith the air. When buried in the earth, animal modified in. bodies putrefy much more slowly; and when a great num- buried ber of carcases are buried in the same pit, the animal mat- ter is converted into a peculiar saponaceous substance, com- posed of a fatty matter combined with ammonia. This sin- gular substance was first observed, as the result of the de- composition of animal bodies, under peculiar circumstances, in the burial ground of the Innocents in Paris, yvhere it had been the practice to deposite the bodies of the poor, each in a separate coffin, in large pits, until they were filled nearly to the top, when the whole was covered over by a layer of earth about a foot deep. These pits usually contained from 1000 to 1500 bodies. It has been arcertained, that bodies, so circumstanced, require about thirty years to be converted into this peculiar fatty matter. 6. As on many occasions it becomes necessary to pre- putrefac- serve, from putrefaction, animal substances to be used as JJ^J** food, so the proper measures, to be pursued with this view, tei. may be become a very important subject of inquiry. It has already prevented. been stated, that the contraries of heat and moisture, name- ly cold and dryness, suspend the process of putrefaction; and accordingly meat in cold countries is preserved in the winter season by being frozen, and drying is a very common expedient for the same purpose. Besides these means of preventing putrefaction, others seem to act by combining with the substance preserved. In this way, it is probable, that chloride of sodium (common salt) and nitrate of pot- ash (nitre) act in preserving flesh. The manner, in which other substances, such as sugar, acids, alcohol &c. act, is not quite so obvious. Dr. Thomson supposes it is by the affinity of these substances for water, whereby they are en- abled to abstract one of the principal agents in putrefaction. 4G INDEX. A Acbtated cerusse, page 377 litharge, compound ce- rate of, 378 yvater of, 378 Acid^ acetic, 255 composition of, 257 medical uses of, 258 properties of, 256 aerial, 213 anthrazothionic, 242 antimonic, 227 antimonious, 227 arsenic, 220 very poisonous, 221 arsenious, 221 its antidote, 222 medical uses of, 222 very poisonous, 222 benzoic, 260 uses in pharmacy, 260 boletic, 272 boracic, 215 medicalluses of, 216 borofluoric, 238 calcareous, 213 camphoric, 266 -carbonic, 213 carbonic, as a constituent of the atmosphere, 470 cai bonic, composition of,214 cetic, 425 chloric, 184 chloriodic, 237 chlorocarbonic, 236 chlorocyanic, 241 , chromic, 223 citric, 262 columbic, 226 crystallized citric, 262 dephlogisticated muriatic, 6 ferrocyanic, 243 ferrocyanic, account of the discovery of, 244 ferrocyanic, properties of, 245 ferruretted chyazic, 243 fluoboric,238 fluoric, 228, 239 fluosilicic, 239 formic, 250 gallic, 249 hydriodic, 195 hydrochloric, 186 hydrochloric, account of the discoveries, which led to ascertaining the true na- ture of, 187 hydrochloric, composition of, 193 hydrochloric, may be oxidi- zed, 191 hydrochloric, properties of, 190 hydrocyanic, 230 hydrocyanic, composition of, 235 hydrocyanic, Gay-Lussac's process for obtaining, 231 hydrocyanic, history of the discovery of, 233 hydrocyanic, medical pro- perties of, 235 hydrocyanic, plants which yield, 477 604 INDEX. Acid, hydrocyanic', properties of, 235 hydrocyanic, Proust'9 pro- cess for obtaining, 233 hydrocyanic, Scheele's pro- cess for obtaining, 230 hydrocyanic, Vauquelin's process for obtaining, 232 hydrofluoric, 228 hydrofluoric, may be oxidi- zed, 229 hydroselenic, 205 hydrosulphuric, 202 hydrosulphurous, 204 hydrotelluric, 207 hydrothionic, 202 hyperoxymuriatic, 184 hyponitrous, 212 hypophosphorous, 219 hyposulphurous 201 iodic, 194 kinic, 271 laccic, 270 lactic, 267 liquid hydrochloric, 192 hydrochloric, medi- cal uses of, 193 hydrosulphuric, 203 sulphuric, 197 sulphuric, how ma- nufactured, 197 sulphuric, may be ox- idized, 199 sulphuric, medical properties of, 200 lithic, 247 malic, 266 margaric, 424 marine, 186 mellitic, 265 mephitic, 213, molybdic, 224 molybdous, 225 moroxylic, 269 * muriatic, 186,'l92 nitric, 208 composition of, 210 may be oxidized, 209 medical properties of, 211 vapour of, destroys contagion, 211 Acid, nitrous, 212 of sugar, 251 of the sugar of milk, 261 oleic, 425 oxalic, 251 oxychloric, 185 oxygenized muriatic, 6 oxyprussic, 241 perchloric, 186 phlogisticated sulphuric,200 phosphatic, 218 phosphoric, 216 phosphoric, composition of, 218 phosphorous, 218 prussic, 230 plants which yield, 477 purpuric, 248 pyrotartaric, 268 saccharine, 251 saclactic, 261 selenic, 204 silicated fluoric, 239 silicofluoric, 239 silicofluoric, account of the discovery of the true na- ture of, 239 silicofluoric, properties of, 240 sorbic, 253 suberic, 270 succinic, 254 sulphocyanic, 242 sulphuretted chyazic, 242 sulphuric, 196 composition of, 200 sulphurous, 200 . tartaric, 258 properties of, 259 telluric, 206 tungstic, 225 vitriolic, 197 uric, 247 composition of, 248 zumic, 272 Acids, 184 as animal constituents, 53S definition and classifica- tion of, 283 fifth class of, 246 INDEX. 605 ' Acids, fifth clas« of, tables of, 280, 281, 2K2 first class of, 184 tables of, 274, 275 foreign, in plants, 515 fourth class of, 236 table of,279 present in animal sub- stances, 587 second class of, 207 second class of, tables of, £76, 277, 278 third class of, 228 table of, 278 vegetable, 477 Adipocire, 573 AeXal acid, 213 Affinity, chemical, 459 chemical, opinions of Bergman on, 460 chemical, opinions of Berthollet on, 460 heterogeneous, 459 homogeneous, 458 Air, atmospheric, 46 < atmospheric, changes pro- duced upon, by respiration, 589 atmospheric, composition of, 465 atmospheric, discovery of the compound nature of, 466 depldojnsticated, 4 em nyreal, 466 fi:.i:d, 213 foul, 466 light inflammable, 18 phlogisticated, 13 Albumen, 522 coagulated, 523 uncoagulated, 522 Alcohol, 409 absolute, 410 ammoniated, uses of, in pharmacy, 411 Alkali, caustic fossil, 158 cau-tic mineral, 158 caustic vegetable, 154 mild fossil, 312 mild vegetable, 301 phlogisticated, 305 Alkali, prussian, 305 volatile, 149 Alloy of copper and tin, 98 zinc, 98 lead and antimony, 91 platinum and copper, 116 silver and copper, i 10 tin and antimony, 95 iron, 95 lead,95 zinc, 95 Aloes, 509 Alum, 346 composition of, 349 medical properties of, 349 properties of. 348 saturated with its earth, 349 Alumina, 171 acetate of, 350 -and-am monia,sulphate of, 349 -and-ammonia, super- sulphate of, 346 -and - potash,sul phate of, 349 -and-potash, supersul- phate of, 346 carbonate of, 350 contracts by heat, 446 fluate of, 350 hydrate of, 172 hydrochlorate of, 346 hydrofluate of, 350 mellate of, 350 nitrate of, 350 phosphate of, 350 plants contain, 517 sulphate of, 346 Aluminum, 65 Amalgam of gold, 113 tin, 108 zinc, 108 Amber, 506 salt of, 254 Ambergris, 532 Ammonia, 149 acetate of, 292 -and-iron, muriate ot. 355 -and-iron, perhydro- chlorate of, 355 606 INDEX. Ammonia-andiron, perhydro- chlorate of, medical properties of, 355 -and-iron, prussiate of, 292 benzoate of, 293 borofluate of, 292 carbonate of, 290 carbonate of, medical properties of, 291 chlorate of, 287 chlorocarbonate of,292 citrate of, 293 composition of, 153 ferrocyanate of, 292 fluate of, 291 hydriodate of, 288 hydrochlorate of, 287 hydrochlorate of, med- ical properties of, 288 hydrofluate of, 291 hydroguretted sulphu- ret of, 289 hydrosulphate of, 289 hydrosulphate of, me- dical properties of, 289 hydrosulphite of, 289 hydrosul phuret of, 289 iodate of, 288 liquid, 151 medical uses of, 151 muriate of, 287 nitrate of, 289 oxalate of, 292 phosphate of, 291 prepared, 290 purpurate of, 292 silicofluate of, 292 soap of, 423 succinate of, 292 sulphate of, 288 sulphite of, 289 sulphocyanate of, 292 sulphuret of, 152 tartrate of, 293 triple prussiate of, 292 urate of, 292 water of, 151 Ammoniac, 509 Ammoniac, sal, 287 vitriolated, 288 Ammoniacal copper, 383 iron, 355 Amnios, liquor of the, 569 Analysis of animal substances, 534 Animal chemistry, 520 constituents, 520 functions, elucidated by chemistry, 588 heat, Crawford's theory of, 593 probable causes of, 594 substances, analysis of, 534 substances, ultimate con- stituents of, 588 Anime, 505 Annealing described, 176 Anthrazothionic acid, 242 Antimonial powder, 405 wine, 407 Antimoniated sulphur, brown, 404 tartar, 406 Antimonic acid, 227 Antimonious acid, 227 Antimony, 44 argentine flowers of, 227 butter of, 46 cerated glass of, 47 chloride of, 46 crocus of, 48 medical uses of, 48 crude, 46 diaphoretic, chemical nature of, 227 glass of, 47 medical uses of, 47 hydroguretted sulphu- ret of, 405 hydrosulphate of, 404 hydrosulphite of, 405 hydrosulphuret of, 404 iodide of, 46 muriate of, 46 oxide of, 45 INDEX. 607 Antimony, oxide of, with sulphur, by nitrate of potash, 48 Antimony, phosphuret of, 46 precipitatedcalx of, 45 sulphuret of, 46 sulphuret of, medical uses of, 48 tartarized, 406 tartrite of, 406 vitrified oxide, with sulphur, 47 Antiseptics, manner of action of, 601 Aqua fortis, 208 Argentine flowers of antimony, 227 Arsenic, 35, 221 acid, 220 chloride of, 36 Fowler's solution of, 304 iodide of, 36 oxide of, 221 phosphuret of, 36 sulphuret of, 36 white, 221 Arsenical neutral salt of Mac- quer, 304 Arsenious acid, 221 Artificial bird-lime, 503 bitter principle, 487 camphor, 502 tannin, 479 Ash-coloured oxide of mercury, 390 Asparagin, 492 Assafcetida, 510 Assimilation, 595 Atmosphere, 465 Atmosphere, and water generally, 464 Atmospheric air, 465 Atomic theory, sketch of, 139 Atoms of undecompounded bo- dies, weights of the, 147 Attraction, corpuscular, 458 of aggregation, 458 of cohesion, 458 Aurum mosaicum, 94 Azote, 13 chloride of, 16 Azote, deutexide of, 15 iodide of, 16 protoxide of, 14 B Balsam of copaiva, 507 Gilead, 507 Peru, 507 styrax, 50T tolu, 507 Balsams, 507 liquid, 507 solid, 508 Barilla, 313 Barium, 60 chloride of, 61 a poison, 61 iodide of, 62 peroxide of, 61 Barytes, 163 acetate of, 364 antidote for, 165 carbonate of, 333 chlorate of, 331 chloride of, 164 ferrocyanate of, 333 fluate of, 333 hydrate of, 164 hydriodate of, 331 hydrofluate of, 333 hydroguretted sulphuret of, 332 hydrosulphate of, 332 hydrosulphite of, 332 hydrosulphuret of, 332 hyperoxymuriate of, 331 iodate of, 331 muriate of, 61 nitrate of, 332 phosphuret of, 164 poisonous, 165 silicated fluate of, 333 silicofluate of, 333 sulphate of, 331 sulphocyanate of, 33S sulphuret of, 165 water, 164 Bases, alkaline salifiable, 149 alkaline salifiable, charac- ters of the, 168 earthy salifiable, 168 608 INDEX. Bases, earthy salifiable, charac- ters of the, 176 salifiable, 149 Bee-slue, 532 Bf.r/.oic acid, 260 Benzoin, 508 flowers of, 260 salt of, 260 Bile, 553 Bird-lime, 503 artificial, 503 Bismuth, 99 chloride of, 100 hydrochlorate of, 386 iodide of, 100 magistery of, 386 muriate of, 386 nitrate of, 386 oxide of, 99 subnitrate of, 386 subnitrate of, as a reme- dy, 387 sulphate of, 386 sulphuret of, 100 Bitter principle, artificial, 487 principles, 485 Black pigment of the eye, 557 Bleaching salt, Tennant's, 161 Blende, 86' Bli-ters, liquor of, 572 Blood, 546 arterial, 590 arterial, effects of gases on, 592 buffy coat of the, 548 changes produced upon,by respiration, 590 colou ring matter of the, 525 constituents of, 547 diseased changes of the, 548 redundant constituents of, hoyv separated, 596 venous, 590 venous, effects of gases on, 592 Blue vitriol, 382 Bodies,compound ponderable, 148 imponderable, 427 ponderable, 3 undecompounded ponder- able, 3 Bodies, undecompounded ponder- able, account of the ar- rangement of, 12.i undecompounded ponder- able, specific gravities of the, 139 undecompounded ponder- able, table of arrange- ment of the, 123 Boiling explained, 443 Boleric acid, 272 Bologna stone, 332 Bone, ^S5 Bones, earth of, 326 Boracic acid, 215 Borax, 316 Borofluoric acid, 238 Boron, 25 Brain, 540 Brass, 98 Brimstone, 32 Brown antimoniated sulphui, 41:4 Burnt hartshorn, 326 Butter, 566 C Cadmium, 86 Caffein, 486 Calamine, 372 Calcareous acid, 213 Calcined magnesia, 167 Calcium, 58 chloride of, 59 medical uses of, 60 iodide of, 60 peroxide of, 59 Calculi, bone-earth, 579 classification of, by Four- croy and Vauquelin, 576 classification of, by Wol- laston, 579 composed of oxalate of - lime,solvents proper for, 580 composed of the phos- phates, solvents proper for, 580 fusible, 579 gouty, 58J mulberry, 579 INDEX. 609 Calculi, mulberry species of, 577 solvents of, 580 uric, 579 uric, solvents proper for, 580 uric species of, 577 Calomel, 103 Caloric, 430 absolute, of bodies, 452 changes in bulk by, 445 in state by, 447 produced by, 445 chemical changes produ- ced by, 453 how it tends to a state of rest, 440 how put in motion, 431 nature of, 430 Camphor, 501 artificial, 502 of volatile oils, 502 Camphoric acid, 266 Cancer, matter of, 571 Cantharides, vesicating principle of, 531 Cantharidin, 531 Caoutchouc, 511 Carbon, 20 bihydroguret of, 24 hydroguret of, 23 hydroguret of, combines with chlorine, 23 sulphuret of, 34 Carbonic acid, 213 as a constituent ol the atmosphere, 470 Cartilage, 540 Cassius, purple powder ot, 3y» Caaior, 532 Caustic fossil alkali, 158 lie, 155 lunar, 395 milder common, loa milder common, uses to the surgeon of, 162 mineral alkali, 158 vegetable alkali, 154 Cerasin, 493 Cerate, Goulard's, 378 Cerin, 500 Cerium, 82 muriate of, 367 nitrate of, 367 oxides of, 82 perhydrochlorate of, 367 pernitrate of, 367 persulphate of, 367 sulphate of, 367 Cerumen, 555 Cerusse, 375 acetated, 377 Cetic acid, 425 Chalk, 325 Chalybeated tartar, 361 Charcoal, 20 chemically the same with diamond, 21 medical uses of, 25 Cheese, 567 Chemical constitution of the hu- man body, 583 examination of nature, 463 Chemistry, animal, 520 science of, 2 vegetable, 476 Chloric acid, 184 Chlorides as animal constituents, 533 found in plants, 515 Chlorine, 6 as a remedy, 9 deutoxide of, 8 protoxide of, 7 used in bleaching, 9 Chloriodic acid, 237 Chlorocarbonic acid, 236 Chlorocyanic acid, 241 Cholesterine, 573 Chromic acid, 223 Chromium, 37 deutoxide of, 38 protoxide of, 38 Chyle, 544 Cinnabar, 107 Citric acid, 262 Citron-coloured ointment, 391 Civet, 532 . Classification of acids explained, 283 4H 616 INDEX. Clay, pure, 171 Cobalt, 77 chloride of, 79 fluate of, 364 hydrochlorate of, 664 hydrofluate of, 364 muriate of, 364 nitrate of, 364 peroxide of, 79 phosphuret of, 79 protoxide of, 78 sulphate of, 364 sulphuret of, 79 Cocculus indicus, bitter principle of, 486 Cocheneal, colouring matter of, 531 Cochenilin, 531 Coffee, bitter principle of, 486 Coin, gold, 113 silver, 110 Colouring matter of the blood, 525 principles, 485 Columbic acid, 226 Columbium, 42 Combustibles, acidifiable, 20 acidifiable, table of, 132,133 acidifying, 18 acidifying, table of, 131 alkalifiable, 50 basifiable, 50 basifiable, forming earthy salifiable bases, 64 basifiable, forming salifiable bases, not alkaline or earthy, 67 basifiable, tables of, 134,135,136,137, 138 intermediate, 44 intermediate, table of, 133 undecompounded, 17 Cembustion,434 Lavoisier's theory of. 436 J Combustion, Priestley's theory of, 434 Stahl's theory of, 434 Thomson's theory of, 436 Compound cerate of acetated li- tharge, 378 Compounds, unsalifiable, 409 Concretions, biliary, 573 pineal, 572 pulmonary, 572 salivary, 572 urinary, 574 with basis of phos- phate of lime, 572 Conduction of heat, 442 Constituents, animal, 520 Copal, 505 Copper, 95 ammoniacal, 383 ammonio-persulphate of, 382 am monio-subpersul phate of, 383 ammonio-subpersulphate of, medical uses of, 383 bipersulphate of, 382 bipersulphate of, medical properties of, 382 hyperoxymuriate of, 381 iodide of, 97 muriate of, 381 peracetate of, 384 perarseniate of, 384 perarsenite of, 384 percarbonate of, 384 perchlorate of, 381 perchloride of, 97 perhydrochlorate of, 381 perhydrofluate of, 384 pernitrate of, 383 *y' peroxide of, 96 * persulphate of, 382 phosphuret of, 97 protochloride of, 97 protoxide of, 96 subpernitrate of, 383 subpersulphate of, 382 sulphuret of, 97 tinning of, described, 98 vitriolated, 382 INDEX. 611 Copperas, 355 Cork, 513 Corrosive sublimate, 105 Cotton, 512 Crassamentum, 547 Cream, 566 of tartar, 307 Crocus metallorum, 48 Crystalline lens, 556 Crystallized citric acid, 262 foliated earth, 320 Crystals of tartar, 307 Cubic nitre, 312 Curd, 567 Cuticle, 538 Cyanogen, 22 D Daphnin, 487 Decomposition of animal bodies after death, 600 Derbyshire spar, 328 Diabetic urine, sugar of, 530 Diamond, chemical nature of, 21 Diaphoretic antimony, chemical nature of, 227 Dippel's animal oil, 531 Diuretic salt, 307 Dragon's blood, 508 Dropsy, liquor of, 571 E Ear, cerumen of the, 555 Earth, crystallized foliated, 320 of bones, 326 Egg, white of the, 522 Elain, 421 Emetin, 489 . action of, on the, animal economy, 489 Enamel of the teeth, 536 Epsom salt, 338 Epulotic cerate, 372 Equality of temperature explain- ed, 445 Ether, aromatic sulphuric, with alcohol, 414 hydrochloric, 412 muriatic, 412 nitric, 414 nitrous, 415 Ether, sulphuric, 413 with alcohol, 414 vitriolic, 413 Ethers, 412 Ethiops, martial, 70 mineral, 107 per se, 101 Eudiometers, 467 Expectorated matter, 571 Extract, Goulard's, of lead, 378 Extractive, 488 Eye, humours of the, 556 F Feces, 548 Ferrocyanic acid, 243 Ferruretted chyazic acid, 243 Fibrin, animal, 524, 583 vegetable, 499 Fire damp, 24 Fixed air, 213 oils, 418 Flint, 174 . Flowers, martial, 355 of benzoin, 260 Fluoboric acid, 238 Fluoric acid, 228, 239 Fluorine, 12 Fluor spar, 328 Fluosilicic acid, 239 Flux, black, 301 yvhite, 301 Formic acid, 250 Fossil alkali, mild, 312 vitriolated, 311 Fuci, ashes of, furnish carbonate of soda, 313 Fuming liquor of Boyle, 289 Libavius, 93 Fungin, 514 Fusible salt of urine, 319 Galbanum, 509 Galena, 91 Gallic acid, 249 Gall-stones, 573 Gamboge, 510 Gases, heavy inflammable, 24 respirable, 591 unrespirable, 592 Hartshorn, burnt, 326 salt of, 290 volatile liquor of, 290 Heat, 430 conduction of, 442 instruments for measuring, 454 latent, of Dr. Black, 452 radiation of, 440 relative quantities of, in bo- dies, 444 Hematin, 485 Homberg's pyrophorus, 348 Honey, 530 Human body, chemical constitu- tion of the, 583 Humour, aqueous, 556 vitreous, 556 Humours of the eye, 556 Hydriodic acid, 195 Hydrechloric acid, 186 Hydrocyanic acid, 230 Hydrofluoric acid, 228 Hydrogen, 18 arsenuretted, 36 carburetted, 24 phosphu retted, 30 selenuretted, 44 sulphuretted, 202 su persulphuretted,204 telluretted, 50, 207 Hydroguretted sulphur, 204 Hydroselenic acid, 205 Hydrosulphuric acid, 202 Hydrosulphurous acid, 204 Hydrotelluric acid, 207 Hydrothionic acid, 202 Hygrometers, 469 Hyperoxymuriatic acid, 184 Hyponitrous acid, 212 Hypophosphorous acid, 219 Hyposulphurous acid, 201 612 INI Gastric secretion, 551 as a remedy, 553 Gelatin, 520 Gland, 540 Glass, bottle, 175 crown, 175 described, 175 flint, 175 Glassy phosphoric acid, 327 Glauber's salt, 311 Glucina, 170 carbonate of, 345 fluate of, 345 hydrofluate of, 345 nitrate of, 345 phosphate of, 345 sulphate of, 344 Glucinum, 65 Glue, chemical nature of, 522 Gluten, 497 Gold, 110 chloride of, 112 fulminating, 152 mosaic, 94 muriate of, 397 perhydrochlorate of, 397 perhydrochlorate of, as a remedy, 398 pernitrate of, 398 peroxide of, 112 peroxide of, medical pro- perties of, 112 persulphate of, 398 phosphuret of, 112 protoxide of, 112 sulphuret of, 113 Golden sulphur, 405 Goulard's extract of lead, 378 Gouty calculi, 581 Graphite, 72 Green, Scheele's, 384 vitriol, 355 Guaiacum, 506 Gum, 482 tragacanth, 493 Gum-resins, 508 Gunpowder, composition of, 300 Gypsum, 324 H Hair, 543 Hartshorn, 149 I Ice, manner in which it melts ex- plained, 451 Incombustibles, table of, 131 undecompound- ed, 13 Indian rubber, 511 Indigo, 496 Ink, sympathetic, 364 INDEX. 613 Ink, writing, 360 Inulin, 493 Instruments for measuring heat, 454 Iodic acid, 194 Iodine, 11 chloruret of, 237 Ipecacuanha, emetic principle of, 489 Iridium, 118 oxides of, 119 Iron, 67 acetate of, 361 ammoniacal, 355 -and-ammonia, phosphate of, 358 arseniate of, 358 carbonate of, 357 carburets of, 72 cast, 68 chromate of, 359 cold short, 75 ferrocyanate of, 359 hot short, 98 hydrochlorate of, 353 iodide of, 72 medical uses of, 75 muriate of, 353 nitrate of, 357 peracetate of, 361 medical uses of, 361 perarseniate of, 358 percarbonate of, medical properties of, 358 perchloride of, 72 perferrocyanate of, 359 pergallate of, 360 perhydrochlorate of, 354 perhydrochlorate of, tinc- ture of, 354 permuriate of, 354 pernitrate of, 357 peroxide of, 71 peroxide of, medical uses of, 71 perphosphate of, 358 persuccinate of, 360 persulphate of, 356 persulphuret of, 75 pertartrate of, 362 Iron, phosphate of, 358 phosphuret of, 74 protochloride of, 71 protosulphuret of, 75 protoxide of, 70 medical uses of, 70 prussiate of, 359 red oxide of, 71 rust of, 358 scales of, 70 subbipersulphate of, 356 subperphosphate of, 358 sulphate of, 355 medical proper- ties of, 356 tartarized, 361 tripersulphate of, 357 tungstate of, 359 vitriolated, 355 Isinglass, chemical nature of, 522 J James's powder, 405 Jelly, 484 K Kali, pure, 154 Kelp, 313 Kermes mineral, 404 Kinic acid, 272 Lac, 505 Laccic acid, 270 Lactic acid, 267 Lead, 87 acetate of, 377 medical uses of, 377 black, 72 carbonate of, 375 carbonate of, uses in phar- macy of, 376 chlorate of, 374 chloride of, 91 chromate of, 376 fluate of, 376 horn, 91 hydrochlorate of, 374 hydrofluate of, 376 614 INDEX. Lead, hyperoxymuriate of, 374 iodide of, 91 muriate of, 374 nitrate of, 375 peroxide of, 89 phosphuret of, 91 protoxide of, 88 red, 90 red oxide of, 90 semi-vitrified oxide of, 89 semi-vitrified oxide of, uses of, in pharmacy, 89 subacetate of, 377 subhydrochlorate of,374 submuriate of, 374 subnitrate of, 375 sugar of, 377 sulphate of, 37 4 sulphuret of, 91 vinegar of, 378 white, 375 Lie, caustic, 155 Ligament, 540 Light, 427 Lignin, 513 Lime, 160 -and-antimony, phosphate of, 405 -and-antimony, phosphate of, medical properties of, 406 benzoate of, 329 biphosphate of, 327 burning of, 326 carbonate of, 325 carbonate of, medical pro- perties of, 326 chlorate of, 323 chloride of, 161 composition of, 162 ferrocyanate of, 329 fluate of, 328 hydrate of, 161 hydriodate of, 323 hydrofluate of, 328 hydroguretted sulphuret of 325 hydrosulphate of, 824 hydrosulphite of, 325 hydrosulphuret of, 324 hyperoxymuriate of, 323 Lime, iodate of,32S iodide of, 162 kinate of, 330 moroxylate of, 330 muriate of, 59 nitrate of, 325 oxalate of, 329 oxidized, 161 oxymuriate of, 161 phosphate of, 326 a constituent in bone, 535 medical uses of, 327 phosphuret of, 162 plants contain, 517 quadri phosphate of, 327 silicofluate of, 329 stone, 325 subphosphate of, 328 sulphate of, 324 anhydrous, 324 sulphocyanate of, 329 sulphuret of, 162 tartrate of, 329 tungstate of, 328 water, 161 medical uses of, 161 with potash, a caustic, 162 Liniment, volatile, 423 Liquid ammonia, 151 potash, 155 Litharge, 89 Lithia, 159 carbonate of, 322 nitrate of, 322 sulphate of, 322 Lithium, 58 Liver of sulphur, 157 Logwood, colouring matter of, 485 Looking glasses, sdvering of de- scribed, 108 Lunar caustic, 395 M Magistery of bismuth, 386 Magnesia, 167 bicarbonate of, 341 bicarbonate of, medical properties of, 341 calcined, 167 INDEX. 615 Magnesia, carbonate of, 340 carbonate of, medical properties of, 341 chlorate of, 338 fluate of, 342 hydriodate of, 338 hydrofluate of, 342 hyperoxymuriate of, | 338 medical uses of, 168 muriate of, 63 nitrate of, 339 phosphate of, 342 plants which contain, 517 sulphate of, 338 sulphate of, medical uses of, 339 sulphuret of, 168 tartrate of, 342 vitriolated, 338 white, 340 Magnesium, 63 chloride of, 63 Malic acid, 266 Manganese, 79 chloride of, 81 deutoxide of, 80 hydrochlorate of, 365 muriate of, 365 nitrate of, 366 peroxide of, 81 persulphate of, 366 phosphuret of, 81 protoxide of, 80 sulphate of, 365 sulphuret of, 81 Marble, 325 Margaric acid, 424 Marine acid, 186 Marrow, 542 Martial flowers, 355 Massicot, 88 Mastich, 504 Matter, expectorated, 571 general properties of, cau- sing chemical changes, 457 of cancer, 571 Medullin, 513 Mellite, 350 Mellitic acid, 265 Membrane, 540 Mephitic acid, 213 Mercury, 100 acetate of, 393 ammoniated perchloride of, 106 -and-ammonia, muriate of, 288 | -and-ammonia, subni- trate of, 390 -and-ammonia, subni- trate of, medical uses of, 391 -and-ammonia, suboxy- muriate of, 105 ash-coloured oxide of, 390 bisulphuret of, 107 bisulphuret of, medical uses of, 107 carbonate of, 392 chlorate of, 388 corrosive muriate of, 105 hydrofluate of, 392 hyperoxymuriate of, 388 mild muriate of, 103 nitrate of, S90 oxymuriate of, 105 peracetate of, 393 perchlorate of, 388 perchloride of, 105 perchloride of, medical uses of, 106 perchloride of,poisoning by, 106 periodide of, 106 pernitrate of, 391 pernitrate of, uses in pharmacy of, 391 peroxide of, 102 peroxide of, medical uses of, 103 perphosphate of, 392 perphosphate of, medi- cal uses of, 892 persulphate of, 389 persulphate of, medical properties of, 390 phosphuret of, 106 protiodide of, 106 616 INDEX. Mercury, protochloride of, 103 protochloride of, medi- cal uses of, 104 protoxide of, 101 protoxide of, uses in pharmacy of, 102 red precipitate of, 102 submuriate of, 103 sulphate of, 388 sulphuret of, 107 sulphuret of, medical uses of, 107 superpersulphate of, 389 supersulphate of, 388 yelloyv subsulphate of, "389 Microcosmic salt, 319 Milk, 565 cows', 566 sugar of, 530 woman's, 568 Mineral, kermes, 404 medical proper- ties of, 405 turpeth, 389 Minium, 90 Molybdenum, 39 oxide of, 40 sulphuret of, 40 Molybdic acid, 224 Molybdous acid, 225 Moroxylic acid, 269 Morphia, 490 action on the human system of, 490 Mortar, component parts of, 163 Mucous network, 539 Mucus, animal, 526 of the nose, 555 vegetable, 483 Muriatic acid, 186,192 Muscle, 536 Musk, 533 Myricin, 500 Myrrh, 510 Nail, 536 Narcotic salt, 215 Natron, prepared, 312 Natron, vitriolated, 311 Nature, chemical examination of, 463 Nerve, 541 Nickel, 75 chloride of, 77 hydrochlorate of, 363 muriate of, 363 nitrate of, 363 peroxide of, 76 phosphuret of, 77 protoxide of, 76 sulphate of, 363 sulphuret of, 77 Nicotin, 487 Nitre, 299 cubic, 312 fixed, 301 spirit of, 208 sweet spirit of, 415 Nitric acid, 208 Nitrogen gas, 13 Nitrous acid, 212 gas, 15 dephlogisticated, 14 Nitrum flammans, 289 semivolatile, 289 Nose, mucus of the, 555 Nux vomica, poisonous principle of, 491 O Ochre, yelloyv, 172 Oil of vitriol, 197 Oils, animal, 531 fixed, 418 uses in pharmacy of,420 vegetable, 499 volatile, 416 uses in medicine of, 417 Olefiant gas, 23 Oleic acid, 425 Oleum tartari per deliquium, 303 Olibanum, 509 Opium, narcotic principle of, 490 Opoponax, 510 Osmazome, 527 Osmium, 119 oxide of, 120 INDEX. 617 Oxalic acid, 251 Oxide, carbonic, 21 of antimony, wiih phos- phate of lime, 405 Oxidized iron, in plants, 517 manganese, in plants, 517 water, 472 Oxychloric acid, 185 Oxygen, 4 Oxyprussic acid, 241 P Palladium, 116 chloride of, 116 hydrochlorate of, 400 muriate of, 400 nitrate of, 400 oxide of, 116 sulphate of, 400 sulphuret of, 117 Pancreatic secretion, 553 vPerchloric acid, 186 Pericardium, liquor of the, 557 Peroxidized water, properties of, 473 Peruvian bark contains extrac- tive, 489 Pewter, 95 Phlogisticated alkali, 305 sulphuric acid, 200 Phosgene gas, 236 Phosphoric acid, 216 glassy, 327 Phosphorous acid, 218 Phosphorus, 26 bihydroguret of, 31 Homberg's, 60 hydroguret of, 30 medical uses of, 32 oxide of, 28 perchloride of, 29 periodide of, 30 protiodide of, 29 protochloride of, 28 slow combustion of, products of, 218 sulphuret of, 35 Pio-omel, 527, 584 Pierotoxin, 486 Plaster of Paris, 3 24 Platinum, 113 deutosul phuret of, 115 fulminating, 152 medical employment of, 116 muriate of, 399 perchloride of, 115 perhydrochlorate of, 399 peroxide of, 114 perphosphuret of, 115 persulphuret of, 115 protochloride of, 114 protophosphuret of, 115 protosulphuret of, 115 protoxide of, 114 sulphate of, 399 Plumbago, 72 Pollenin, 499 Polychroite, 485 Ponderous spar, 331 stone, 328 Potash, 154 acetate of, 307 medical uses of, 307 -and-antimony, tartrate of, 406 -and-antimony, tartrate of, medical properties of, 407 -and-antimony, tartrate of, properties of, 407 -and-iron, prussiate of, 305 -and-iron, sulphate of, 356 -and-iron, tartrate of, 361 -and-iron, tartrate of,me- dical properties of,361 -and-lime,tartrate of,S29 -and-magnesia, tartrate of, 342 -and-soda,tartrate of,320 -and-soda,tartrate of.me- dical properties of,321 arseniate of, 304 arsenite of, 304 arsenite of, medical pro- perties of, in solution, 304 4T bio INDEX. Potash, bicarbonate of, 303 bicarbonate of.solution of, used in medicine, 303 binarseniate of, 304 binoxaiate of, 306 bitartrate of, 307 bitartrateof, medical pro- perties of, 308 carbonate of, 301 carbonate of, how obtain- ed, 302 carbonate of, medical properties of, 303 carbonate of, properties of, 302 chlorate of, 294 chlorate of, explodes yvith combustibles, 294 chlorate of, medical em- ployment of, 295 chloride of, 157 citrate of, 309 composition of, 157 ferrocyanate of, 305 ferrocyanate of, metallic precipitations by, 306 fluate of, 305 fluosilicate of, 305 hydriodate of, 296 hydrofluate of, 305 hydroguretted sulphuret of. 298 hydrosulphate of, 297 hydrosulphate of, medi- cal uses of, 298 hydrosulphite of, 298 hydrosulphuret of, 297 hyperoxymuriate of, 294 iodate of, 296 liquid, 155 medical uses of, 156 muriate of, 52 nitrate of, 299 gunpowder contains, 300 medical pro- perties of,301 oxychlorate of, 295 perchlorate of, 295 Potash, plants contain, 515 preparation of, for medi- cal use, 155 pyrotartrate of, 309 silicofluate of, 305 soap of, 42 1 sulphate of, 296 sulphate of, medical pro- perties of, 297 sulphite of, 297 sulphocyanate of, 305 sulphuret of, 157 supertartrite of, 307 surgical uses of, 157 tartrate of, 308 medical pro- perties of,309 tar trite of, 308 triple prussiate of, 305 Potassium, 50 chloride of, 52 chloride of, animal sub- stances containing, 586 chloride of, medical uses of, 53 hydruret of, 53 iodide of, 53 peroxide of, 52 phosphuret of, 53 sulphuret of, 53 Powder, antimonial, 405 James's, 405 Precipitations of metals by hydro- sulphate ofpotash, 299 of metals by hydro- sulphite oi potash, 299 Prepared ammonia, 290 natron, 312 Principles, bitter, 485 colouring, 485 Propolis, 532 Proximate constituents, chief, of animals, 583 Prussian alkali, 305 blue, 359 native, 358 Prussiate of iron, 359 INDEX. oli, Prussiate of soda-and-iron, 319 strontian-and-iron, 337 Prussic acid, 230 Pure clay, 171 Purpuric acid, 248 Pus, 569 good,570 ill-conditioned, 570 Putrefaction, animal, 600 animal, in buried bodies, 601 animal, means of preventing, 601 animal, products of, 600 Pyrites, cubic, 75 magnetic, 75 Pyro-acetic spirit, 257 Pyrometer, Wedgewood's, 456 Pyrophorus, Homberg's, 348 Pyrotartaric acid, 268 Q Quassia, bitter principle of, 486 Quassin, 486 Quicklime, 160 Quicksilver, 100 yvhite calx of, 106 R Radiation of heat, 440 Radical vinegar, 255 Red lead ore of Siberia, 376 precipitate of mercury, 102 Resins, animal, 532 vegetable, 503 Respirable gases, 591 Respiration, 580 Rete mucosum, 539 Rhodium, 117 deutoxide of, 118 perhyd rochlorate of,401 pernitrate of, 401 peroxide of, 118 persulphate of, 401 protoxide of, 118 Uochelle salt, 320 Rosin, 504 Rust of iron, 358 S Saccharine acid, 251 Saccharine matter, animal, 530 Saclactic acid, 261 Saffron, colouring matter of, 485 of mars, 71 Sagapenum, 510 Sago, chemical nature of, 496 Saint Ignatius's bean, poisonous principle of 491 Sal alembroth, 288 ammoniac, 287 fixed, 59 secret, 288 de duobus, 296 polychrestus, 296, 297 Salifiable bases, 149 alkaline, 149 table of, 180 as animal consti- tuents, 534 earthy, 168 table of, 181 neither alkaline nor earthy, 177 neither alkaline nor earthy, ta- ble of, 182,183 present in animal substances, 588 present in plant»r 515 Saliva, 550 Salop, chemical nature of, 496 Salt, calcareous marine, 59 common, 55 yields carbonate of soda by chemical decomposition, 313 digestive, 52 diuretic, 307 Epsom, 338 febrifuge, 52 fusible, of urine, 319 Glauber's, 311 microcosmic, 319 narcotic, 215 of amber, 254 of benzoin, 260 620 INDEX. Salt, of lemons, essential, 306 of Seignette, 320 of steel, 355 of wood-sorrel, 306 petre, 299 regenerated sea, 52 Rochelle, 320 sea, 55 sedative, 215 wonderful perlated, 317 Salts, 286 Salts of alumina, 346 ammonia, 287 barytes, 331 glucina, 344 lime, 323 lithia, 322 magnesia, 338 oxidized antimony, 403 bismuth, 386 cerium, 367 cobalt, 364 copper, 381 gold, 397 iridium, 402 iron, 353 lead, 374 manganese, 365 mercury, 387 nickel, 363 osmium, 402 palladium, 400 platinum, 399 rhodium, 401 silver, 394 tellurium, 408 tin, 379 titanium, 402 uranium, 368 zinc, 369 potash, 294 silica, 353 soda, 310 strontian, 335 thorina, 352 yttria, 343 zirconia, 351 present in animal substan- ces, 587 Sarcocoli, 482 Saturnine ointment, 377 Scammony, 510 Scheele's green, 384 Scheelium, 40 Scillitin, 486 Sea yvater, analysis of, 471 Secretion, 594 gastric, 551 pancreatic, 553 Secretions, excrementitious, 595 Selenic acid, 204 Selenite, 324 Selenium, 43 Semen, 565 Senna, extractive is present in, 488 Serum of the blood, 547 Silica, 174 composition of, 176 forms glass with potash or soda, 175 plants containing, 517 Silicated fluoric acid, 239 Silicofluoric acid, 239 Silicum, 66 r, Silver, 108 arsenite of, 396 chlorate of, 394 chloride of, 109 coin, 110 fluate of, 396 fulminating, 152 horn, 109 hydrofluate of, 396 hyperoxymuriate of, 394 iodate of, 394 iodide of, 110 muriate of, 109 nitrate of, 395 surgical and me- dical uses of, 395, 396 oxide of, 109 phosphuret of, 110 sulphate of, 394 sulphuret of, 110 Sinovia, 557 Size, chemical nature of, 522 Skim-milk, composition of, 568 Skin, 538 true, chemical nature of, 539 INDEX. 621 Voap, hard, 423 of ammonia, 423 of potash, 424 of soda, 423 soft, 424 Soaps, 422 Soda, 158 acetate of, 320 ammonio phosphate of, 319 -and-iron, prussiate of, 319 animal substances contain- ing, 585 bicarbonate of, 316 bicarbonate of, medical pro- perties of, in solution, 316 biphosphate of, 319 borate of, 317 carbonate of, 312 carbonate of, medical pro- perties of, 315 carbonate of, properties of, 315 chlorate of, 310 composition of, 159 dried carbonate of, is offici- nal, 315 ferrocyanate of, 319 fluate of, 319 fluosilicate of, 319 hydriodate of, 310 hydrofluate of, 319 hydroguretted sulphuret of, 312 hydrosulphate of, 311 hydrosulphite of, 312 hydrosulphuret of, 311 hyperoxymuriate of, 310 iodate of, 310 muriate of, 55 nitrate of, 312 phosphate of, 317 medical pro- perties of,318 plants containing, 516 silicofluate of, 319 soap of, 423 subborate of, 316 medical uses of, 317 sulphate of, 311 Soda, sulphate of, medical proper- ties of, 311 sulphate of, yields carbo- nate of soda, by chemical decomposition, 314 sulphocyanate of, 319 tartrate of, 320 triple prussiate of, 319 urate of, 319 Sodium, 54 chloride of, 55 chloride of, animal sub- stances containing, 586 chloride of,yields carbo- nate of soda, by chemi- cal decomposition, 313 peroxide of, 55 phosphuret of, 57 sulphuret of, 58 Solder, plumber's, 95 Soluble tartar, 308 Sorbic acid, 253 Spar, Derbyshire, 328 fluor, 328 ponderous, 331 Specific gravities of the unde- compounded bodies, ta- ble of, 139 Spermaceti, 422 Spirit of Mindererus, 293 nitre, 208 sea salt, 186 wine, 409 pyro-acetic, 257 Squill, bitter principle of, 486 Starch, 494 how converted into su- gar, 481 Steam, heat becomes non-distri- butable in, 451 Stearin, 421 Steel, 72 blistered, 74 cast, 74 natural, 7o salt of, 355 Stone, Bologna, 332 Storax, 508 Strontian, 165 carbonate of, 336 022 INDEX. Strontian, chlorate of, 335 chloride of, 166 ferrocyanate of, 337 fluate of, 337 hydrate of, 166 hydriodate of, 335 hydrofluate of, 337 hyperoxymuriate of, 335 iodate of, 335 muriate of, 62 nitrate of, 336 sulphate of, 335 triple prussiate of, 337 Strontium, 62 chloride of, 63 peroxide of, 62 Strychnin, 491 action of, on the ani- mal economy, 492 Suber, 513 Suberic acid, 270 Sublimate, corrosive, 105 Subsulphate of mercury, yelloyv, 389 Succinic acid, 254 Sugar, 480 acid of, 251 of diabetic urine, 530 of lead, 377 of milk, 530 acid of the, 261 of saturn, 377 Sulphocyanic acid, 242 Sulphur, 32 animal substances con- taining, 585 chloride of, 33 golden, 405 hydroguretted, 204 iodide of, 33 liver of, 157 Sulphuretted chyazic acid, 242 hydrogen, 202 Sulphuric acid, 196 Sulphurous acid, 200 Sulphurous salt of Stahl, 297 Supersulphate of alumina-and- ammonia, 346 of alumina-and- potash, 346 Supersulphuretted hydrogen, 204 Supertartrite of potash, 307 Supporters of combustion, table of, 131 of combustion, unde- compounded, 4 Sweat, 563 Sweet spirit of nitre, 415 T Tacamahac, 504 Tannin, 478 artificial, 479 Tantalum, 42 Tartar, 807 antimoniated, 406 chalybeated, 361 cream of, 307 crystals of, 307 emetic, 406 salt of, 301 soluble, 308 vitriolated, 296 Tartaric acid, 258 Tartarized antimony, 406 iron, 361 vegetable alkali, 308 Tartrate of potash-and-soda, 320 Tartrite of antimony, 406 potash, 308 Tears, 554 Teeth, chemical nature of, 536 Telluric acid, 206 Tellurium, 48 chloride of, 49 oxide of, 49 sulphuret of, 50 Temperature, equality of, explain- ed, 445 Tendon, 540 Thermometer, Celsius's, 455 common, 454 De Lisle's, 455 Fahrenheit's, 454 Leslie's, 455 Reaumur's, 455 Thorina, 173 carbonate of, 352 hydrochlorate of, 352 muriate of, 352 nitrate of, 352 INDEX. 625 Thorina, sulphate of, 352 Thorinum, 66 Tin, 91 ammonio-pernitrate of, 380 bisulphuret of, 94 fluate of, 380 hydrochlorate of, 379 medical uses of, 95 muriate of, 379 nitrate of, 380 oxymuriate of, 93 perchloride of, 93 perhydrochlorate of, 379 perhydrofluate of, 380 permuriate of, 379 peroxide of, 92 persulphate of, 380 phosphuret of, 94 plate, 95 protochloride of, 93 protoxide of, 92 sulphate of, 379 sulphuret of, 94 Tincal, 316 Tincture of acetated iron, 361 muriated iron, 354 Titanium, 120 deutoxide of, 121 muriate of, 402 percarbonate of, 403 perhydrochlorate of, 402 pernitrate of, 403 peroxide of, 121 protoxide of, 121 sulphate of, 403 Tobacco, characteristic principle of, 487 Trona, 316 Tungsten, 40, 328 oxide of, 41 sulphuret of, 41 Tungstic acid, 225 Turner's cerate, 372 Turpeth mineral, 389 Tutty, 85 U Ulmin, 484 Unrespirable gases, 592 Unsalifiable compounds, 409 Uranium, 83 hydrochlorate of, 368 muriate of, 368 nitrate of, 368 peroxide of, 83 protoxide of, 83 subnitrate of, 369 sulphate of, 368 Urea, 528, 584 Uric acid, 247 Urine, 558 composition of, 561 diseased states of, 562 pink-coloured sediment of, 562 Vapour of yvater, as a constituent of the atmosphere, 468 Varec, 313 Varnish of leaves, 501 Vegetable acids, 477 alkali, caustic, 154 mild, 301 tartarized, 308 vitriolated, 296 chemistry, 476 Vegetables, proximate constitu- ents of, 476 ultimate constitu- ents of, 518 Verdigris, medical uses of, 385 preparation of, 384 Vermilion, 107 Vinegar, chemical nature of, 255 medical uses of, 258 of lead, 378 properties of, 256 radical, 255 Vitriol, blue, 382 green, 355 oil of, 197 yvhite, 370 Vitriolated ammoniac, 288 copper, 382 fossil alkali, 311 iron, 355 magnesia, 338 natron, 311 zinc, 370 Vitriolic acid, 197 624 INDEX. Volatile alkali, 149 mild, 290 liniment, 423 oils, 416 W Water, At0 beloyv a certain tempera- ture, contracts by neat, 446 composition of, 473 discovery of the composi- tion of, 474 manner in which it freezes explained, 450 may be cooled below the freezing point, yvithout becoming ice, 448 of acetated litharge, 378 of acetate of ammonia, 293 of acetate of ammonia,me- dical properties of, 293 of ammonia, 151 of carbonate of ammonia, 290 of potash, 155 peroxidized.properties of, 473 sea, analysis of, 471 Wax, 500 myrtle, 501 uses iu pharmacy of, 501 Whey, 5C7 White lead, 375 White magnesia, 340 of the egg, 522 vitriol, 370 Wine, antimonial, 407 chalybeate, 5(X spirit of, 409 Wodanium, 87 Wolfram, 359 Wolfiamium, 40 Yelloyv ointment, 591 Yttria, 169 carbonate of, 344 Yttria, fluate of, 344 hydrochlorate of, 343 hydrofluate of, 344 muriate of, 343 nitrate of, 344 sulphate of, 34 > Yttrium, 64 Zinc, 84 acetate of, 372 medical uses of, o7j carbonate of, 372 medical pro- perties of,37 2 chlorate of, 369 chloride of, 85 floyvers of, 84 fluate of, 372 hydriodate of, 370 hydrochlorate of, 370 hydrofluate of, 372 hyperoxymuriate of, 369 impure oxide of, 8jj iodate of, 370 iodide of, 85 muriate of, 370 nitrate of, 371 oxide of, 84 medical uses of,85 phosphuret of, 86 sulphate of, 370 medical uses of, 371 sulphuret of, 86 vitriolated, 370 Zirconia, 172 carbonate of, 351 fluate of, 351 hydrochlorate of, 351 hydrofluate of, 351 muriate of, 351 nitrate of, 351 sulphate of, 351 Zirconium, 66 Zumic ajcid, 272 •art: . 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