LIBRARY UNIVERSITY OF CALIFORNIA. OK Mrs. SARAH P. WALSWORTH. Received October, 1894. Accessions No. Class Mo. ELEMENTS CHEMISTRY; CONTAINING THE PRINCIPLES OF THE SCIENCE, *. -' * *>. EXPERIMENTAL AND PRACTICAL, INTENDED AS A TEXT-BOOK FOR ACADEMIES, HIGH SCHOOLS, AND COLLEGES. ILLUSTRATED WITH NUMEROUS ENGRAVINGS. BY ALONZO GRAY, A. M. Teacher of Chemistry and Nat. Hist, in the Teachers Sem., Andover, Mass. SECOND EDITION, REVISED AND ENLARGED. NEW YORK: PUBLISHED BY DAYTON AND S A X T O N, SCHOOL BOOK PUBLISHERS, Corner of Fulton and Nassau Streets. BOSTON : SAXTON AND PIERCE. 1841. fll? Entered according to Act of Congress, in the year 13-iO, Bv AI.ON/.O GRAY, In the Clerk's Office of the District Court of Massachusetts. \ ALLEN, MORRELL, AND WARDWELL, PRINTERS. ', > ^5 PREFACE. IN compiling tlie first edition of this work, the author attempted to prepare a text-book which should be well fitted for elementary instruction. Most of the works on chemistry appeared to him to be either too profound, on the one hand, for those who were just commencing the study, or too superficial, on the other, for those who wished to obtain a scientific knowledge of the subject. The design was to avoid these two extremes, and com- bine the scientific with the popular and useful parts of the subject. The rapid sale of the first edition, and its intro- duction into 'several colleges, has led to the inference that the attempt has not been wholly unsuccessful. The author has therefore been induced to revise and enlarge the work, and put it into a permanent form. A large amount of matter, and numerous engravings, have been added, for the purpose of rendering the work better adapted to academies and other schools. It is believed that greater success would attend the efforts of teachers in this branch of science, if more attention were given to the principles of chemistry, and less to its details. The fundamental principles being thoroughly understood by the * student, he is prepared to attend to the details with greater pleasure and success, as he will be able to connect the effects with their appropriate causes. Under the influence of this belief, the author has given a greater prominence to the imponderable agents and the thir- PREFACE. teen non-metallic substances, than to other parts of the work. Most of the illustrations and experiments are introduced in this part, so as to present and illustrate the philosophy of chemical combinations, and the general nature of the com- pounds thus formed ; in other words, the causes of chemical changes and the mode of studying them. By the introduction of numerous experiments and illus- trations, the object has been to give to the work a prac- tical character, so that the teacher, with a very simple apparatus, and with limited means, may be able to give numerous experimental illustrations to his classes. The im- portance of studying chemistry experimentally, is admitted by all ; and to aid teachers in constructing the more simple forms of apparatus, many notes and drawings have been added, and experiments described, which may easily be performed by those who are not privileged with more costly and extensive means of illustration. In the arrangement of the imponderable agents, the phe- nomena of common and voltaic electricity, electro-magnet- ism, and magneto-electricity, are classed as effects of one- agent electricity. In the arrangement of the simple substances, the logical order has been adopted ; that is, each simple substance is described, and then its combinations with those only which have been previously described ; so that only one substance with which the pupil is unacquainted is presented at a time. This classification appears to be the most convenient for presenting the different compounds, and less liable than any other to confuse the mind of the learner. "This order, how- ever, has been adopted only with the simple substances and their binary compounds. The salts occupy a separate chapter, in the arrangement of which Turner's Chemistry has been made the basis. Several new salts, and one entire family, the silicates, have been added. PREFACE. P Organic chemistry has become so extensive, and so far a distinct branch of the subject, that a short chapter only is inserted. For a complete description of these compounds, the student is referred to Thompson's Chemistry, " Organic Bodies," which is the most extensive and valuable work on the subject which has hitherto appeared. The chapter on Analytical Chemistry has been consider- ably enlarged ; but the methods of analysis have become so accurate, the details so minute, and the processes so com- plicated, that those who would obtain a full mastery of the subject, must consult works which treat particularly of :ical analysis. Sufficient only has been inserted to give the pupil some idea of the nature of the processes, and to enable him to test, if not actually to analyze, the sub- stances which are-mentioned. The Glossary of chemical terms has been selected from that prepared by Daniell, of London, and adapted to this work. The table of contents has been much enlarged, and a complete analysis of the work presented, in the form of topics, which are intended to be used instead of questions ; the topics being so arranged that, when the teacher sug- gests one, the pupil may give a complete description of it. This plan, it is believed, will prevent the evils incident to direct questions, while it will secure all their advantages. Chemical formulae have been extensively adopted. This appears highly important, especially for those who intend to become thorough students in the science. The notation, (the use of symbolical language,) to express, in a condensed form, complicated chemical changes, seems to be as useful in chemistry as in a ] gebra, and, although these symbols may be unintelligible to the common reader, he who will thorough- ly study them will find them the most efficient aid to a clear, definite, and easy comprehension of the whole science. In the description of the ponderable bodies, brevity has PREFACE. been consulted, as far as was consistent with perspicuity. The illustrations and descriptions are much more extended in the first two hundred pages than in other parts of the work. The method of description which is employed in natural history has been adopted, where the subject did not require a more popular style. By this means, and by using different kinds of type, a large amount of matter has been condensed into a small compass, while, at the same time, that which is more important to be studied is rendered conspicuous. Many subjects of minor importance are only alluded to, and reference frequently made to more extensive works. The source from which most of the materials have been drawn, is Turner's Chemistry. The works of Henry, Silli- man, Webster, and Griffin's Chemical Recreations, have been frequently consulted, and also many original papers in the scientific journals of the day ; and it is confidently be- lieved that the work contains the most valuable recent discoveries up to the present time, so far, at least, as they have been made known to the scientific public. The acknowledgments of the author are here due to Professor Charles B. Adams, of Middlebury College, for important aid, especially in the department of Organic Chemistry. A. G. TEACHERS' SEMINARY, Andover, September, 1841. CONTENTS. INTRODUCTION. Page Science defined Physical and Natural science 21 Definition of matter how many properties does it embrace ? 21 DIVISION or NATURAL SCIENCE. I. NATURAL PHILOSOPHY method and object of. 21 II. CHEMISTRY method and object of. 22 III. NATURAL HISTORY method and object of 22 PLAN OF THE WORK. PART I. IMPONDERABLE AGENTS why so called 22 II. CHEMICAL AFFINITY definition of. 23 III. PONDERABLE BODIES chemical and natural substances. 24 Division of substances ; simple and compound bodies. ... 24 Analysis and synthesis; arrangement of chem. substances 24 PART FIRST. IMPONDERABLE AGENTS. CHAPTER I. CALORIC. The term heat how used meaning of caloric 25 1. Sensible caloric defined. 2. Insensible caloric do 25 SECT. 1. SENSIBLE CALORIC COMMUNICATION OF. The most important property of sensible caloric 26 I. Conduction meaning and illustration of. 26 Conducting power ; how does it differ in bodies ? 26 Different degrees of this power illustrated 27 1. Conducting power of solids ; illustrated by conductometer 27 Best and poorest conductors, metals, stones 27 Uses of conductors, benevolence of God illustrated 28 Ratio of the conducting power of solids 28 2. Conducting power of liquids ; how are liquids heated ? Ills 28 Heat applied at the top of liquids in a glass jar 29 3. Conducting power of gases ; how are they heated ? 29 II. Radiation defined; radiant caloric, how projected ? 30 3 . Law of the intensity of heat at different distances 30 2. Degree of radiation, dependent upon what ? 30 Difference between bright, and dark or rough surfaces, Ills 30 Greater radiating power of rough surfaces, depends on what?. . 30 8 CONTENTS. 3. Rapidity of radiation dependent upon .what ? 31 III. Disposition of Radiant Caloric reflect., absorb., transmit. 31 1. Reflection of caloric ; law of reflection, angles of incidence and reflection. Concave mirrors described 31 2. Absorption of caloric ; depends upon what ? 32 Best absorbers, reflectors, and radiators 32 Color of surface ; its effect upon the power of absorp., Ills 32 3. Transmission of caloric ; through air and gases, glass, etc 32 Opinions of Leslie, Brewster, De la Roche, and other chemists. 33 Radiant caloric modified by its connection with solar light 33 IV. Theories of Radiation how many are worthy of notice ?. . 33 1. Theory of Pictet, described 33 2. Theory of Prevost, do. grounds of preference 33 V. Application of the Theory of Prevost to the Expl. of -carts Phen. 1. The phen. of the mirrors explained ; apparent radiation of cold.. 34 2. Formation of dew, process described and explained 34 Quantity of dew ; dep. upon what? grass, and polished surface.. 34 Why is there no dew in a cloudy night ? 35 VI. Cooling of Bodies different modes by which it is effected. 35 Velocity of cooling, defined; law of cooling, according to Newton. 35 VII. Prac. Application of the Laws of Conduct, and Radiant Caloric. Best materials for windows ; double walls, doors, windows 35 Object of clothing ; kind best for different season* of the year 36 Effects of Free Caloric. I. General Law Caloric expands all Bodies; Liquids, Solids, Gases. 1. Caloric expands solids : illustrated by what ? 36 2. Equal degrees of caloric expand some solids more than others. . . 36 Illustrated by pyrometer ; description of pyrometer 36 3. Effect of equal add'ns of caloric on the same solid at dif. temp's. 37 Expansion of brass and iron rods in the higher or lower temp s. . 37 4. Uniformity in the expansion of certain solids 37 II. Caloric expands Liquids more than Solids. 1. Illustrated by heating water in a glass tube, common thermom'r 38 2. Effect upon different liquids of equal degrees of caloric 38 3. Effect upon the same liquids of equal degrees at different temp's 38 Apparent exceptions to the general law that heat expands 38 III. Caloric expands Gases more than Solids or Liquids. 1. The expansion of air ; in glass ball, bladder 38 2. Law of the expansion of gases at all temperatures 39 Difference between gases, and solids or liquids 39 Theory of expansion ; caloric and cohesion, how related ? 39 IV. Apparent Exceptions to the General Law. Water near the point of congelation ; Illustration 40 V. Force of Expansion when Water freezes. Florentine Academicians ; experiments of Major Williams 40 Theory, or the cause of expansion when water freezes 40 VI. Advantages of this Excep. wisdom and benevolen. of God 40 Process of freezing water ; effect if the contractions continued. ... 41 Cast iron and antjmony, how affected in cooling ? 41 VII. Practical Uses of the General Law of Expansion and Contract. Banding of wheels, steam-engine boilers, gallery at Paris 41 Winds ; depend upon what ? land and sea breezes 42 Thermometers ; by whom invented ? 42 1. Air thermometers j plan of Sanctorius, illustrated 42 CONTENTS. 9 Objections to air for the common purposes of a thermometer .... 43 2. Differential thermometer of Leslie ; mode of construction 43 Best substance for thermometers ; solids, liquids, or gases ? 43 3. Mercurial thermometer; construction and graduation 44 Different scales; Fahrenheit's, Reaumur's, De Lisle's, Celsius's 45 4. Register thermometer; construction, object, and principle of... 45 Pyrometers ; derivation and meaning of the term 46 1. Pyrometer of Wedgwood ; founded upon what property 46 2. do. of Daniell ; construction of. 46 3. Metallic thermometer of Brequet ; construction, Illustrated 46 Amount of knowledge obtained by therm's and other instruments 47 SECT. 2. INSENSIBLE CALORIC. Specific caloric ; meaning of, illustrated 47 Methods of determining specific heat of solids and liquids 48 Laws of Specific Heat, 1, 2, 3, 4, 5 48 Practical inference from the doctrine of specific heat 49_ Effects of Insensible Caloric. I. Liquefaction states in which bodies exist 49 1 . Point of liquefaction ; fusion, congelation 49 2. Caloric of fluidity ; Illustr., quantity in different substances. ... 49 3. Freezing mixtures; how produced? salt and snow 50 4. Limit to the degree of cold ; greatest cold by these processes. . . 51 5. Absolute amount of heat ; estimated by what means ? 52 II. Vaporization defined, difference between gas and vapor. .. 52 Definition of volatile and fixed bodies ; liquids how vaporized 52 Ebullition ; \ . Boiling point defined ; is it fixed ? 52 2. Circumstances which modify the boiling point of liquids 53 Pressure of the atmosphere ; variations of 53 Barometer, construction and illustration of. 53 1. Law of the boiling point as the pressure diminishes 53 Mercury frozen under the exhausted receiver of an air-pump . . 53 2. Law of the boiling point as the pressure increases 54 Marcet's digester ; construction of. . 55 Absorption of free caloric in ebullition, Illustration 55 Table of the latent heat of different vapors 56 Steam ; its formation and laws of expansive force 56 Sensible and insensible caloric of steam at all temperatures 57 Application of Steam to practical Purposes. 1 . Warming rooms ; water baths, dyeing vats, etc 57 2. Steam engine ; invention of. principle illustrated 58 3. Steam generator of Mr. Perkins ; steam artillery 58 Distillation; process illustrated and described 59 Evaporation difference between it and ebullition 59 1. Evaporation of different liquids ; depends upon what ? 59 2. Effect of increased and diminished pressure upon evaporation. . . 59 3. Extent of surface ; how does it affect the rapidity of evaporation 60 4. State of the atmosphere; " " " 60 5. Absorption of free Caloric by Evaporation ; cryophorus described CO 6. Cause of evaporation ; how have some accounted for it ?....,... 61 7. Uses of evaporation ; cooling rooms, warm climates 61 Effect of perspiration explained ; fire kings, oven girls 61 Injurious effects of evaporation, miasma, fever and ague 62 10 CONTENDS. Hygrometers ; reduced to three principle* 62 1. Saussure's hygrometer ; depends up^n what property ? 62 2. Leslie's hygrometer ; depends upon what property ? 62 3. Hygrometer depending upon the quantity of dew, etc 62 Application of the Laws of Insensible Caloric to the Expl. Nat. Phen. 1. Processes of thawing and freezing ; effect upon climate 62 2. Effect of vaporization ; to modify the heat of summer 63 3. Effect of condensing vapors ; rain, source of the cold 63 4. Effect of freezing water; to modify the approach of winter 63 Why are the shores of a country warmer in winter, etc 63 SECT. 3. SOURCES OF CALORIC AND OF COLD. 1. Sun ; concentration of its rays, degree of heat 64 2. Chemical action ; combustion defined 64 3. Condensation ; machinery, friction, percussion 64 4. Vital action ; how is caloric produced in animals ? 65 Sources of cold, what? 65 SECT. 4. NATURE OF CALORIC. Theory of Sir W. Herschel and Prof. Airy ; undulatory theory 65 Theory of Newton ; what supposition did he make ? 65 CHAPTER II. LIGHT. I. Physical Properties of Light belong to what science ? 66 Velocity of light ; disposition of it 66 II. Reflection the circumstances which govern it 66 III . Refraction defined, refrangibility, Illustration 66 IV. Decomposition of Light how many kinds of rays ? 67 1. Colorific rays; mode of separating them by prism, Illustration.. 67 Opinion of Wollaston, of Brewster, illuminating power 68 2. Calorific rays ; their position, and degree of refrangibility 68 3. Chemical rays ; their position in the spectrum Relations to water, to hydrogen ; bleaching effects 1 36 Relations to animals ; uses ; 1. Bleaching process, theory 1 -'-7 2. Disinfecting agency ; dissecting rooms ; diseases of skin 138 Hypochlorous acid; Symb. Equiv. Sp. gr. process, properties .. 138 Chlorous, chloric, and perchloric acids ; process, properties 139 SECT. 3. IODINE. Symb. Equiv. Sp.gr.; history of discovery ; natural history .... 140 Process ; Physical and chemical properties, tests, uses 142 lodic acid ; process, properties ; periodic, and chloriodic acids 143 SECT. 4. BROMINE. Symb. Equiv. Sp. gr. ; history of discovery 143 Natural history ; process, physical and chem. properties illustrated 144 Bromic acid; properties, chloride of bromine; bromide of iodine. . . 145 SECT. 5. FLUORINE. Symb. Equiv. ; natural history, properties as far as known 145 SECT. 6. HYDROGEN. Symb. Equiv. Sp.gr.; history; nat. history, processes 146 1. By heated iron ; Illustration 146 2. By zinc and acidulated water ; theory, impurities 147 Physical properties ; soap bubbles, method of filling gas bags. . 148 Aerostation ; description of balloons 149 Chemical properties; illustrated, theory, relations to animals.. 149 Protoxide of hydrogen, water ; Symb. Equiv. Sp. gr., process. ... 150 Physical and chem. properties illustrated, solvent properties 151 Composition, eudiometer described ; compound blowpipe 152 Heat produced by blowpipe ; binoxide of hydrogen, properties .... 153 Hydrochloric acid ; history, natural history, process, theory 154 Woulfe's Appa., physical and chemical properties, illustrated .... 155 Constitution ; uses and impurities 156 Hydriodic acid; Symb. Eq. Sp.gr.; process, properties, tests .... 156 Hydrobromic acid; Symb. Equiv. Sp. gr. ; properties 157 Hydrofluoric acid; history, process, theory, uses illustrated 157 CONTENTS. . 15 SECT. 7. NITROGEN. Sy mb. Equiv. Sp. gr. ; history of discovery 158 Natural history ; process, 1. By phosphorus 159 2. By sulphur and iron. 3. By muscle and nitric acid 159 Theory of process ; physical and chemical properties 159 Effect on combustion ; respiration, its nature 159 Common air; physical properties, elasticity illustrated 160 Pressure of the air ; how discovered ? 160 Extent and composition of the atmosphere 161 Thetny of the diffusion of gases of different sp. gr.; Illustrated. 162 Impurities of the air ; eudiometry, uses of the air 163 Protttride of nitrogen ; history, process, theory of, properties 163 Respiration of; effect upon animals 164 Binoxide of nitrogen; history of discovery, process 164 Tht-ory of process, properties, illustrated, affinity for water 165 1 1 yi>o nitrous acid ; properties, nitrous acid, history 165 Processes, properties, respiration of. Nitric acid, history 166 Process, illustrated, impurities, properties 167 Chemical properties, illustrated, uses 168 J\'itrolnjilrochloric acid, aqua regia ; nitrohydrojluoric acid 168 (Juailrochloride of nitrogen ; process, properties 169 Teriodide of nitrogen ; Sy mb. Equiv. properties 169 Ammonia; history, process, theory of, properties, tests, uses 170 SKCT. 8. CARBON. Symb. Equiv. Sp. gr. ; nat. hist.; the diamond, where found, uses 172 Plumbago, anthracite, bituminous coal, peat, and lamp-black 173 Charcoal ; 1. Process by slow combination of wood 173 2. By distillation of wood. 3. By hot sand 173 Properties, hardness, theory of its absorbing properties 174 Clarifying agency, combustion of, durability of, infusibility, uses 175 Carbonic oxide ; carbonic acid, history of discovery 1 76 Nat. hist, process, theory of, relation to flame, to water 177 Fermenting liquors, best test of carbonic acid, solidification of. ... 178 Relations to animals, choke-damp 179 Sources of carbonic acid, respiration explained 180 I h oridc, perchloridc of carbon, Chloro-carbonic acid, chloral. . . . 181 Periodide and protiodidc of, bromide of carbon, properties 181 Dirarburet of hydrogen ; history, process, properties. Illustration.. 182 Olefiunt gas, or 2 carburet of hydrogen, Symb. Equiv. Sp. gr 182 History, process, theory of, properties, Ills. ; action of chlorine. . . . 183 | Carburet of H. etherine, 3 carburet, parrijfine, eupione, naphtha. . 183 Naphthaline, paranaptkaline, idrialine, camphene, and citrene 184 Gas lirrlits ; history, process, portable gas, fire-damp 184 Efforts'of Davy ; discovery of Wollaston 186 Effect of gauze wire upon flame ; safety lamp, construction, etc. . . 187 Bicarb urei' of nitrogen or ci/anogen, history, process, properties. . . 188 Cyanic, fuhninic. and cyanuric acids 188 Parn cyan-uric acid, chloride, bichloride, and bromide of cyanogen.. . 189 Hydrocyanic acid. Process, properties 189 SECT. 9. SUI-PHUR. Symb. Equiv. Sp. gr. ; nat. hist., process ; Illus., sublimation. ... 190 Properties, effect of heat, structure, impurities, uses 191 Hypviulphurous and sulphurous acids, process, theory, crucibles. 192 16 CONTENTS. Hyposulphuric acid, process, properties ; sulphuric acid, process . . 194 Hydrous sulphuric acid, manufacture of, theory 195 Properties, affinity for water ; Illus. decomposition, tests 190 Uses ; dichluride, iodide, and bromide of sulphur l!>7 Hydrosulphuric acid, process, theory of l'.>7 Properties, liquid form, tests, uses ; Illustration Production of sulphur; Illustration; hydrosvlphurovs acid !!>!> Bisulphuret of carbon, or alcohol of sulphur, carbosulphuric acid . . 1 99 Sulphuret and bisulphurct of cyanogen 200 Hydrosulphocyanic and cyanohydrosulphuric acids 200 SKCT. 10. PHOSPHORUS. Symb. Equiv. Sp. gr. ; history, source 200 Process, properties, inflammability ; Illustrated v 201 Theory of the heat and light, relation to animals. . . . T 202 Oxide of phosphorus ; hypophosphorous acid 202 Phosphorous acid, process ; phosphoric acids 203 Phosphoric acid, process, properties ; pyro and meta phosp. acids . . 204 Sesquic hloride of phosphorus, Symb. Equiv., process, properties .. '204 Perchloride, protiodide, sesquiodide, and periodide of phosphorus . . 205 Protobromide, perbromide, phosphuret of hydrogen, properties 205 Perphosphuret of hydrogen, process, properties, inflammability of, 206 Jack o' the lantern ; sulphur et of phosphorus 207 SECT. 11. BORON. Discovery ; process, property 207 Boracic acid; source, process, evaporating dishes 208 Tcr chloride of boron ; fiuoboric acid, suphuret of boron 209 SECT. 12. SELENIUM. Discovery, oxide of, seJenious acid, properties 210 Selenic acid ; chloride and bromide of, hydroselenic acid 211 SECT. 13. SILICON. Symb. Eq., discovery, properties, silicic acid, nat. history, process, 212 Chloride, bromide, and sulphuret of silicon, fluosilicic acid 213 ' ** CHAPTER II. CLASS II. METALS, WITH THEIR PRIMARY COMPOUNDS. General properties of metals, metallic lustre 214 Sp. gr. of; malleability defined 214 1. Ductility, tenacity. 2. Hardness. 3. Structure. 4. Fusibility 215 5. Volatility. 6. Affinity for other simple bodies 215 Combustibility ; number and date of discovery 217 Classification of the metals 217. 218 ORDER I. Metals which, by Oxidation, yidd Alkalies or Earths. SECT. 1. METALLIC BASES OF THE ALKALIKS. Potassium ; history of discovery 218 Process, properties, combustibility; Illustration 219 Protoxide of potassium ; properties, hydrate of; Ills., tests 220 Potassa; teroxide, iodide, bromide, fluoride, and chloride of. 221 Hyduret, nituret. sulphurets, phosphurets and seleniuret of. 222 CONTENTS. 17 Cyanuret, properties ; sulphocyanuret of ....................... 223 Sodium; Symb. Equiv. Sp.gr ................................ 223 Process, properties, affinity for oxygen, ..................... ... 223 Protoxide of soda, process ; sesquioxide, chloride of, origin, uses. 224 Iodide, bromide, fluoride, sulphuret, and cyanuret of ............ 225 Chloride of soda, alloys of sodium and potassium ............... 225 Lithium ; protoxide of, or lithia, process, properties, fluoride of. ... 226 SECT. 2.' METALLIC BASES OF THE ALKALINE EARTHS. fsarium ; protoxide of, or baryta, how distinguished ............. 227 Uinoxide, chloride, iodide, bromide, fluoride, sulphuret .......... 228 Cyanuret, sulphocyanuret, phosphuret of ...................... 229 Strontium ; protoxide, strontia, peroxide and chloride of. ......... 229 Iodide of, fluoride, protosulphuret ............................ 230 Calcium; protoxide of, or lime, peroxide, chloride, uses; iodide.. 230 Bromide, fluoride, bisulphuret, phosphuret of, chloride of lime. . . . 231 Mti ! ni'siiim ; discovery, process, properties ..................... 232 Protoxide of, or magnesia, properties, uses ..................... 2!>3 Chloride of, iodide, bromide, fluoride .......................... 233 SECT. 3. METALLIC BASKS OF THE EARTHS. ^Humlniiim; discovery, process, properties, sesquioxide of ........ 234 Scsquichloride, sesquisulphuret, sesquiphosphuret .............. 235 fjluciniuni ; Symb ; Equiv. Sp. gr. ; discovery, properties ........ 236 JSi'squioxide of, glucina, discovery, process, properties ........... 236 Yttrium ; Symb. Equiv. ; process, properties .................... 236 Thorium ; bymb. Equiv. ; process, properties, protoxide, do ...... 237 yrab. Equiv. ; discovery, process, properties ........ 237 ORDER II. Metals the Oxides of which are neither Alkalies nor Earths. SECT. 1. METALS WHICH DECOMPOSE WATER AT A RED HEAT. tMi>i7 Tellurium, oxide of; tellurous acid, chloride, sulphurets Copper; nat. history, process, properties, uses, red or dioxide of.. i2C>!) Black, or protoxide of, copper black, properties, binoxide of. 270 Bichloride, chloride, diniodide, sulphuret, copper pyrites, tests. . . . 270 Alloys ; brass, Dutch gold, pinchbeck, bell-metal, bronze '-'To Lead ; protoxide, red oxide, peroxide, chloride, and iodide of L'71 Alloys of lead ; common pewter, fine solder, pot metal 271 SECT. 3. METALS THE OXIDES OF WHICH ARE REDUCED TO THE METALLIC STATE BY A RED HEAT. Mercury ; cinnabar, propeities, protoxide of, properties 273 Binoxide, process, properties; protochloride, process, properties.. 274 Bichloride of mercury, or corrosive sublimate, process, properties. 274 Protosulphuret, bisulphuret, properties, cinnabar, ethiops mineral. 275 Bicyanuret of; amalgams, described, protiodide, etc 275 Silver, ; process, properties, cupellation, uses 276 Oxide, fulminating silver, torpedoes, chloride of. 277 Iodide, sulphuret, cyanuret, and alloys of. 277 Gold ; nat. history, process, quartation, properties 278 Protoxide, binoxide, and teroxide of; fulminating gold 279 Proto, and terchlorides of; alloys, water-gilding, gold powder.... 280 Platinum; properties, spongy platinum, proto, and binoxide of. ... 281 Sequioxide, protochloride, bichloride of 281 Protiodide, biniodide, protosulphuret, and bisulphuret of 282 Fulminating platinum, palladium, rhodium 282 Osmium, osmic acid, iridium, latanium 282 CHAPTER III. CLASS III. SALTS, OR SECONDARY COMPOUNDS. SECT. 1. CRYSTALLIZATION. Crystal and crystalography defined 283 Planes, faces, edges, angles, primary and secondary forms of 284 CONTENTS. 19 I. Prisms have six-sided or four-sided bases 284 (1.) Right Prisms J . Hexahedron, or cube 284 2, 3. Right square and right rectangular prisms 284 4, 5. Right rhombic and right rhomboidal prisms 284 6. Regular hexagonal prism 285 (2.) Oblique Prisms 7. Rhombohedron. 8. Obi. rhombic prism 285 9. Oblique rectangular prism. 10. Oblique rhomboidal prism .... 285 II. Octohedrons 11. Regular octohedron. 12. Square octoh. 285 13. Rectangular octohedrons. 14. Rhombic octohedrons 286 III. Dodecahedrons 15. Rhombic dodecahedron 286 Secondary forms ; cleavage defined, faces and direction of 286 Isomorphism, crystallogenic attraction, water of crystallization. . . . 287 SECT. 2. OXY-SALTS. General formula for the composition of the salts 288 1 . Sul/ihates of potassa, soda, Glauber's salts 289 Of lithia, ammonia, baryta, strontia, lime, gypsum 289 Of magnesia, alumina, manganese, protoxide of iron 291 Of protoxide of zinc, (white vitriol,) nickel, cobalt, chromium. . . . 292 Of copper, (blue vitriol,) mercury (turpeth mineral,) silver 293 Nitro-sulphuric acid, sulphate of soda, lime, potassa, and magnesia 294 Ammonia, soda, iron, chrome, and mangan. alums. 2. Sulphites 294 :>. >\"it. rates of potassa, (nitre beds,) of soda, ammonia 295 Of baryta ; pyrotechny, green-fire 296 Of strontia, (red-fire,) lime, magnesia, protoxide of copper 297 Nitrate and dmitrate of protoxide of lead, of mercury, of silver. ... 297 Properties, illustration, lunar caustic, indelible ink 298 I . Nitrites. 5. Chlorates of potassa, properties 299 Lii -iti-r matches, chlorate of baryta, process, properties 300 6. Perch/orates. 7. Chlnrites. 8. Hypochlorites. 9. lodates 301 lodate of potassa. 10. Bromatcs. 1 1 . Phosphates 302 I. Phosphates triphosph., diphosph., and phosph. of potassa 302 Of soda and ammonia, ammonia, Tune, magnesia, ainm. and mag. 303> Triphosphate of silver. 1 1. Pyrophosphates 304 III Mctaphospkntes of soda, baryta, silver, etc 305 12. Jlrseniates ; of soda, table of compounds 305 13. Jrsenitts ; general properties, tests 306 14. Chromates; of potassa, lead. 15. Borat.es; of soda, borax.. .. 307 16. Carbonates ; of potassa, soda, ammonia 308 Of baryta, strontia, lime, magnesia 310 Of iron, copper, lead, white lead, mercury 311 17. Double Carbonates 312 18. Silicates ; simple, bi, tri, and quadri silicates 312 SECT. 3. ORDER II. HYDRO-SALTS ; acids of 314 SECT. 4. ORDER III. SULPHUR-SALTS; constitution of. 316 SECT. 5. ORDER IV. HALOID-SALTS; constitution and descrip. of 319 CHAPTER IV, NATURAL SUBSTANCES. ORGANIC CHEMISTRY. Nature of organic compared with inorganic compounds 321 Decomposition of, formation of; relation to inorganic bodies 322 VEGETABLE CHEMISTRY. Proximate principles, proximate analysis, ultimate analysis 322 Results of Wfthler, Liebig, Pelouse, and Dumas 323 20 CONTENTS. 1. Amides, or .imidets ; theory, meaning of oxamide and amide. .. 323 2. Benzoyl; theory. 3. Ethers; theory, radical of the ethert 323 4. Pyracids ; theory. 5. Theory of substitutions; dehydrogenizing 3:23 SECT. 1. VEGETABLE ACIDS ; general properties, description of. .. 323 SECT. 2, VEGETABLE ALKALIES ; constitution and description of 332 SECT. 3. NEUTRAL SUBSTANCES; constitution and description of 334 SECT. 4. OILS ; fixed and volatile oils described 337 SECT. 5. SPIRITUOUS AND ETHEREAL SUBSTANCES ; description of 341 SECT. 6. COLORING MATTERS ; lakes, dyes, etc 3-13 SECT. 7. FERMENTATION ; saccharine, vinous, putrefactive 345 SECT. 8. GERMINATION ; growth and food of plants 347 CHAPTER V. ANIMAL CHEMISTRY. SECT. 1. PROIIM. PRINCIPLES NEITHER ACID OR OLEAGINOUS. . . . 349 SECT. 2. ANIMAL ACIDS ; general principles and description of. ... 349 SECT. 3. ANIMAL OILS AND FATS ; description of 350 ,SECT. 4. COMPLEX ANIMAL SUBSTANCES; blood, chyle, etc 351 CHAPTER VI. ANALYTICAL CHEMISTRY. SECT. 1. ANALYSIS OF MIXED GASES. 1 . Gaseous mixtures containing oxygen 356 2. Gaseous mixtures containing nitrogen 3;7 3. Gaseous mixtures containing carbonic acid 357 4. Gaseous mixtures containing hydrogen and other infl'le bodies 357 SECT. 2. ANALYSIS OF MINERALS AND METALLIC ORES. I. Analysis of minerals soluble in acids, with effervescence 357 II. Analysis of minerals insoluble in acids 358 III. Analysis of minerals containing carbonate of lime 358 Silica, oxide of iron and magnesia : . . . . 3.>H IV. Tests of the metallic ores 35! 1 . Ores of antimony. 2. Of lead. 3. Of mercury 35!) 4. Ores of zinc. 5. Of tin. (5. Of iron. 7. Of copper. 8. Of silver 359 9. Ores of gold and platinum ; earthy sulphates 359 SECT. 3. ANALYSIS OF MINERAL WATERS. 1. Rain water. 2. Well and spring water. 3. Acidulous springs. 360 4. Alkaline springs. 5. Chalybeate and saline springs 360 6. Sulphureted springs ; detection of hydrosulphuric acid 361 Test tubes ; filtration ; filtering process ; supports 361 APPENDIX; Wollaston's synoptic scale of chemical equivalents.. . 364 Cementing ; various cements 3 GLOSSARY 373 GENERAL INDEX 385 INDEX OF PLATES 396 NOTE. F. and Fahr. for Fahrenheit's thermometer. T. refers to Turner's Chemistry. W. to Webster's Chemistry, 3rd Ed. L. to Liebig. B. to Berzelius. Eq. and Equiv. for Equivalent. - Symb. for Symbol or formula. INTRODUCTION. SCIF.M'E is classified knowledge. Physical or Natural Science is the knowledge of the material world. The defi- nition of matter embraces two properties, without which we cannot even conceive of its existence. These properties are cftiiision, which includes length, breadth, and thickness, and impenetrability, or the impossibility that any two portions of matter should occupy the same space. There are other prop- erties, which do not necessarily enter into our conception of matter, but which universally belong to it, such as gravitation, inertia, mobility, etc. Natural Science consists of three great branches, whi(dl are characterized chiefly by peculiar methods of investigation. I. NATURAL PHILOSOPHY employs the method of general ;;'/j/>/r.s ; th'it is, it observes, for example, the gravitation of a stone let fill to the ground, and, neglecting the other proper- ties of the stone, observes the same property in other bodies, and generalizes the phenomena under a law. It is therefore conversant with general laws, but not with all the general laws, for its observation is restricted to the phenomena of pn-n ptibln di stances which can be formed in the laboratory. These are chemical substances. The second division will embrace natural substances, or animal, vegetable, and mineral com- pounds, which have been formed by natural agencies. Chemists divide substances into simple and compound. A simple substance is one which never has been separated into two kinds of matter v$ or which has never been decomposed./, There are about fifty-four simple substances. A compound body ( is one which is composed of two or more simple bodies, of which there are many thousands. ,24 INTRODUCTION. The composition of bodies is ascertained by two methods : 1. /By separating the body into its simple elements, which is called analysis ; t and, 2. By causing the elements to combine and form the body, which is called synthesis.^ Chemical substances are arranged in three general di- visions : I. Non-metallic elements, and their primary compounds with each other. II. Metals, and their primary compounds. III. Salts, or secondary compounds. In the arrangement of the simple substances and their primary compounds, the logical order is pursued ; that is, after describing one substance, the rest are described with the compounds which they form with those previously described. The Salts are divided into four orders : I. Ozy~salts t or those salts the acid or base of which is an oxidized substance. II. Hydro-salts. This order includes no salt, the acid or base of which does not contain hydrogen. III. Sulphur-salts, or those salts, of which the electro- positive or electro-negative ingredient is a sulplutnt. IV. Haloid-salts, including none, the electro-positive or electro-negative ingredient of which is not haloidal, i. e., analogous in composition to sea salt. CHEMISTRY PART I. IMPONDERABLE AGENTS. VI CHAPTER I. CALORIC. THE word heat has two meanings, ^t is the sensation whici we experience when we touch a hot body/t or it is the caust- of the sensation. In the first sense, it is an effect producer onhy upon animals. In the second, it is the cause of a grea' variety of effects in the mineral, vegetable, and animal king- doms. The word caloric (Lat. calor) is used in the latter sense. Where there can be no ambiguity, the word heat is often retained in the same sense. Caloric exists in a free or sensible, and in a latent or insensible state. 1. Sensible Caloric. In this state, caloric is capable of producing the sensation of heat, and of expanding bodies. It has sometimes been called the caloric of temperature. Temperature expresses the power of exciting the sensation, and is proportioned to the quantity of free caloric. A high temperature is owing to a great quantity, and a low temper- ature to a small quantity. 2. Insensible Caloric. In this condition, caloric produces no sensation, but exists, often in great quantity, in substances, without affecting their temperature, and appears to be com- bined with them. 3 i2t> Conduction of Caloric. SECT. 1. SENSIBLE CALORIC. Communication of Sensible Caloric. The most important property of free caloric is its tendency to an equilibrium; that is, a tendency to escape from hotter to colder bodies, so as to produce in all the same degree of temperature. This communication takes place in two ways by conduction, and by radiation. I. Conduction. By this is meant the passage of caloric through a body, from panicle to particle. i-rimfnt. Place bits of phosphorus alon<; an iron rod, and apply heal to one eiui <>f it; the progress of the caloric will be indicated by its igniting the phosphorus. The property in the body, on which this transmission depends, is called the conducting power. If one end of an iron rod be held in the fire, the sons-it inn ofhoat will so.m bo experienced at the other extremity, in consequence of the conduction of caloric from particle to particle along the rod. If the rod be of glass it will he much longer before any heat is felt. Hence different sub- stances conduct caloric irith different degrees of facility. If two bodies are in contact, caloric may be conducted from one to the other. ij|e more permit the contact, otlvr things being equal, the more rttjnd the conduction. This is the reason why a heated body, when grnsppd firmly by t!i hand, will burn it more - :un when held loosely. The contact of two solids with each other, or of a solid with a gas, is not so perfect as that of a solid with a liquid ; and hence the communication is more rapid in the latter C:IM\ When liquids are mixed with liquids, or gases with gases, the contact is still more perfect, and the caloric is more rapidly diffused through the whole. From the two f.ict> which have been mentioned, it follows that the rapidity of conduction from a heattd to a cold body depends upon the conducting power of each substance, and the closeness of conta.t. Conducting Poircr of Sot, 27 Plunge a heated iron into cold water, and again, equally heated, into mercury. In the latter ease, it will cool more rapidly ; lor, while the heat is with equal facility in b.-tii cases from the interior to the surfaee. it is taken from the surfaee mure rapidly by the mercury than by the water. tereury two equal balls, one of iron and the othei Be temperature. The iron Imll will cool the more rapidly, because the caloric is more freely conducted from its in - surface. Plunjje the iron hall into mercury, and the marble into water. The iron \\ilfcool more rapidly, for two" reasons; the heat will come to its surface more freely, and be taken otf by the mercury more rapidly, iron and mercury being each better conductors than marble or water. Of the dillerent forms of matter, 'solids are better conduct- ors of caloric than //\//c/., and liquids than gu- 1. Conducting Power of Solids. This power varies greatly in different solids. This fact may be shown by Fig. 1. the conditctonntrr, (Fig. 1,) [] _ f] |] _ [] II (l.fl which consists of a tin or iron . in which there may be inserted small solid cylinders of the same dimensions, but of different materials. A /:.r/>. Place upon one end of each, bits of phosphorus, and apply to the ,i her ends the sai.ie decree of heat by placing the case over boil in | water The oal >rie will be e.ndueted alon^r | r om one extremity of rru-h ; . and tii- substance which conducts most rapidly will ,'iite the phosphorus. irr to the experiments of M. Despretz, if the con- power of (iold be represented by 1000 Tin . . Siher will be . . ." 973 Lead . . Copper S1 Porcelain Iron 374.3 Fine clay . 11.4 //me . .... IIIIIIIIIOIllll Metals generally are the best conductors of caloric, while furs and porous substances are the poorest conductors. The conductiiur power of stones is next to that of the metals, and crystal line stones are better conductors than the uncryst illized. . 28 Caloric Conducting Power of Liquids. The earths generally are bad conductors. Bricks, glass, dry wood, charcoal, conduct less; and feathers, silh hair, and down, least of all. Among the latter, the finer tfojibre, the less its conducting power. Hence the utility of fine wool and furs in the winter, to prevent the escape of caloric from the body ; while, in the summer, we select those substances for our clothing which have a coarser fibre. In this we see the benevolence of God in furnishing those animals which inhabit the colder regions of the earth, with finer clothing than those which inhabit warm climates. The fur of animals is also finer in whiter than in summer. Snow and ice are poor conductors ; and hence, by a wise constitution, the earth in winter is rarely frozen to any con- siderable depth. The ice and snow keep it warm by pre- venting its vital heat frora escaping. The conducting powers of solids are generally in the ratio of their densities; especially of the same ..substance. In- crease of density will increase the conducting power, and vice versa. 2. Conducting Power of Liquids. In liquids the conduct- ing power is much less than in solids. So feeble is it, that some, among whom is Count Rumford, have denied its ex- istence. But, notwithstanding the slight conducting power of liquids, heat can be diffused through them much more rapidly than through solids. This is effected by a motion among the particles, which brings them successively into contact with the heated surface. If, for example, heat is applied to the Fig. 2. ^bottom of a vessel of water, (Fig. 2,) those particles of water which are in contact with the bottom, are soon heated, and con- sequently expanded and made lighter, so that they are forced to rise, in order to give place to the heavier cold particles, which fall to the bottom. The latter, in turn, are heated, and give place to others ; and thus the process continues until two currents are established, the one of-heated particles rising to the surface, and the other of colder particles falling to the bottom. In this way all the water is soon heated by Conducting Power of Gases. 29 direct contact with the bottom.* A little powdered auiber or gum copal, put into the water, will indicate the direction of the currents. But if heat be applied to the top of the ves- FS- 3. sel, the water at the bottom will remain cold, while that at the top is boiling. Erp. Suspend in a tin cup a hot cannon ball on the top of a jar of water, (Fig. 3,) at the bottom of which is a piece of ice. The water will boil npidly at the top, while the ice remains umuelied. But if the ice is phc.ed upon the top, and heat applied to the bottom, the ice will all be melted before the water can be made to boil. Erp. Or, burn ether (Fig. 4) on the top of a glass fnnin -1 filled with water, into which an air thermome- ter is cemented. The thermometer will not be sensibly affected. A ring of tin should be phced on the top of the water, within half au inch of the sides of the fun- nel ; and the ether, poured within this ring, will burn, without the risk of breaking the ghiss. It has, however, been shown that liquids do conduct heat, independently of any intestine motion. Cut the power is very slight. 3. Conducting Pawn- of Gnats. Gases and vapors conduct heat very slightly, if at all. Their particles move with so much facility when heated, that it is difficult to arrive at any satisfactory results on this subject. Heat may be diffused through them in the same manner as through liquids, but with much greater rapidity. II. Radiation. If a heated body be suspended in the air, its caloric will be diffused both by the currents of air, which circulate to and from its surface, and, in a slight degree, by the conducting power of the air. But if the hand be placed beneath the heated body, a sensation of heat will be perceived, which is not due to either of these causes, but to the direct passage of the rays through the air. For if a heated body be suspended in a vacuum, entirely removed from conducting substances, it will rapidly cool * A Florence flask, or a glass tube, may be used for this experiment, and the water heated by a common tin lamp filled with alcohol. 3 * 30 Radiation of Caloric down to the same temperature with surrounding bodies. Caloric, which is thus thrown off from heated bodies in all directions, like rays of light from the sun, is called radiant caloric. 1. If a thermometer be placed at the distance of two inches from a heated body, it will be affected but one fourth as much as at the distance of one inch ; if it be placed at the distance of three inches, one ninth as much ; if at four inches, one sixteenth as much ; at five inches, one twenty-fifth, etc. Hence, in consequence of a radiation in all directions, the intensity of the heat is in the inverse ratio of the square of the distance. The intensity of light and the force of gravi- tation follow the same law. 2. The degree of radiation, and consequently the intensity of radiant heat, are greatly modified by the kind of surface. Bright, polished surfaces do not radiate so rapidly as those which are dark and rough. Fig. 5. 6 Exp. Take a square tin cup, a, (Fig. 5,) one suit 1 of which is bright, another rough, a third painted black, and the fourth painted white. Fill it with hot water, and bring an air ther- mometer, c, near each side. The rough and black surfaces will radiate more rapidly than those which are white and polished. If the rays of caloric are brought to a focus by the mirror A, the dif- ferent degrees of caloric from the several surfaces will be much more evident.* The greater radiating power of rough surfaces is supposed to be due to the great number of radiating points; or perhaps * The late experiments of Melloni do not seem to confirm this view. By using a cup of marble, whose external surfaces were differently prepared, the first polished, the second smooth but tarnished, the third streaked in one direction, and the fourth in two, crossing each other at right angles, and filling the vessel with hot water, each of the sides projected the same quantity of radiant caloric. Edin. Philos. Jour X&VL 299. Reflection of Caloric. 31 it may be owing to the greater amount of surface exposed within a given space. 3. The rapidity of radiation also depends upon the differ- ence between the temperature of the radiating body and that of the surrounding bodies. Hence, with a given temperature of the latter, the higher the temperature of the radiating body, the more rapid the radiation. * III. Disposition of radiant Caloric. Radiant caloric passes in right lines through a vacuum, through air and gases, with- out any apparent obstruction; but when it falls upon solid or liquid substances, it is disposed of in three ways: 1. It re- bound:, from the surface, or is reflected. 2. It enters into the substance, or is absorbed. 3. It passes through the body, or is transmitted. 1. Reflection of Caloric. When radiant caloric falls upon bright, polished surfaces, it is mostly reflected in lines, which form angles with a perpendicular to the reflecting surface, ! to the angles formed by the same perpendicular, and the lines in which the rays went to the surface. Thus, let BAG (Fig. 6) be a smooth sur- Fig. 6. f '( ', S the incident ray, P the perpendicular to the surface, and R the reflected ray. The angle RAP is equal to the angle PAS. The angle PAS is called the angle of incidence, and PAR the angle of reflection. Light fol- lows the same law. If a concave surface be used, the rays of caloric will be reflected and brought to a focus. This may be shown by two metallic mirrors, as in Fig. 7. a and b Fig. 7. 32 Absorption of Caloric. are two reflectors of polished metal, (brass or tin,) 12 inches in diameter, and segments of a sphere of 9 inches radius. Place them at any convenient distance apart, from 6 to 12 feet. If a heated ball of iron be placed in the focus of or, and an air thermometer in that of 6, the caloric will first radiate to the surface of a, and then he reflected in parallel lines to the surface of 6, whence the rays will be reflected to the focus in which the bulb of the thermometer is placed, and will cause the liquid to descend, showing an increase of tempera- ture. If phosphorus be placed in the focus, it will be ignited. If snow be substituted for the heated ball, the thermometer will show, by the rise of the liquid, a diminution of tempera- ture. As bright, polished surfaces reflect most of the calorific rays which fall upon them, we can see the reason why they are not easily heated. 2. Absorption of Caloric. When radiant caloric falls upon rough, opaque substances, it is mostly absorbed ; that is, it passes directly into the substance, and renders it hot : some of the rays are also reflected. The power of absorption, as well as of radiation and re- flection, depends mostly upon the surface. Those surfaces which reflect most, radiate and absorb least, and those which radiate and absorb most, reflect least. The power of absorp- tion and that of radiation are equal ; and as each increases, the power of reflection diminishes. The color of the surface also affects the power of absorp- tion. Dr. Stark has shown that black surfaces, other things being equal, absorb the most ; dark green next to black ; scarlet next ; and white the least of all colors. Exp. This fact may be shown by placing strips of cloth of different colors upon snow, exposed to the sun's rays ; the black will be found to sink into the snow to the greatest, and the white to the least, depth, because the black absorbs the rays which melt the snow, and the white reflects them. Hence the advantage of painting rooms white, or of whitewashing them : the rays of caloric are thus kept passing from side to side, without being absorbed and conducted away. 3. Transmission of Caloric. When radiant caloric falls upon the surface of transparent solid or liquid bodies, it passes through them in a slight degree. It passes easily through air and other gaseous substances, without sensibly affecting them; but glass and crystalline T/icories of Radiation. 33 pnbstances intercept most of the rays. Prof. Leslie contends tint glass does not permit the rays to pass directly through it, but absorbs them at one surface, and transmits them to the other by conduction, from which they are again radiated. This opinion is supported by Dr. Brewster by an argument drawn from his optical researches. But the experiments of Do la Roche lead to a different conclusion that the calorific rays do pass through glass, although slowly. This opinion is supported by other chemists. The radiant caloric which is associated with solar light passes readily through glass and other transparent bodies. The caloric, in this case, seems to be modified by its con- nection with light, and may be collected into a focus with trie light, as in the case of a burning-glass. Caloric, thus asso- ciated, suffers refraction in passing from one medium to another, and in general is subject to the same laws with light IV. Theories of Radiation. Of the various theories to account for radiation, only two seem worthy of notice. 1. The theory of Pictet supposes that a hot body will radiate caloric to surrounding colder bodies, until the equi- librium is restored, andthen cease. 2. The theory of Prevost supposes that all bodies, what- ever be their temperature, are constantly giving out and receiving radiant caloric. When a body is giving out more r iys than it is receiving, it is cooling. When it gives and receives an equal number, its temperature remains stationary, and is in equilibrium with surrounding bodies. When it receives more rays than it gives off, its temperature is in- creasing. On this theory, all bodies the polar ice, as well as the burning sands of the tropics are constantly radiating and absorbing caloric. Although most of the phenomena of radiation may be explained on both theories, preference is generally given to that of Prevost. The ground of this preference is found in the close analogy between the laws of light and heat. It is well known that luminous bodies continually exchange rays. A feeble light sends rays to one of greater intensity, and the quantity of rays emitted by each does not seem to be affected 34 Application of the. Theory of Prcvost. by the vicinity of other luminous bodies. In like manner all bodies are supposed continually to exchange rays of caloric. V. Application of the Theory of Prcvost to the Explana- tion of various Phenomena. 1. In the experiments with the mirrors, if the ball in the focus of one mirror is of the same temperature with the thermometer in that of the other, and with surrounding objects, the thermometer will remain stationary, because it receives from the ball the same quantity of rays which it sends to it; but if the temperature of the ball be raised above that of the surrounding objects, the thermometer will receive more rays than it imparts, and will consequently show an increase of temperature. ^If ice be substituted for the ball, the thermometer will show a diminution of temperature, be- cause it gives out more rays than it receives. When ice is placed in the focus of a mirror, there is an apparent radiation of cold. But on this theory it is easily explained, and is what might be expected previous to experi- ment.* Cold is a negative term, merely expressing the absence, in a greater or less degree, of caloric. 2. The formation of dew depends upon radiation, and is satisfactorily accounted for on this theory. The earth, during the day, becomes heated by absorbing the sun's rays, and the moisture is driven off into the air. During the night, it radi- ates more caloric than it receives, and becomes colder than the surrounding atmosphere. Successive strata of air charged with moisture, come in contact with the earth, and the moisture is condensed in the form of dew. The quantity of dew will therefore depend upon the radi- ating power of the surface, and the quantity of moisture in the air ; the more rapid the radiation, the more dew will be formed. There is more dew upon grass and leaves than upon stones; and the thermometer will sink 15 or 20 lower, when placed upon grass, than when suspended in the air, or laid on polished surfaces. In India, ice is formed by ex- posing water in pans in a clear night, when the temperature * See Turner, Gth edition, p. 13, note Cooling of Bodies. 35 of the air is never down to the freezing point. But why is there no dew in a cloudy night? Because the clouds reflect back the radiant caloric to the earth, which therefore cannot become cooler than the air. In a clear night, there is no such interchange of rays, and the caloric passes off into the regions of space.* VI. Cooling of Bodies. The cooling of a hot body is effected in two ways, already noticed. When surrounded by solid bodies in contact with it, the heat is carried off by conduction, and the velocity of cooling will depend upon the conducting power. When the heated body is immersed in liquids, the same is true to some extent, although much de- pends upon the mobility of the particles. But when sur- rounded by gases, the cooling takes place by means of con- duction and radiation, and in a vacuum, by radiation alone. Velocity of cooling means the number of degrees lost in a given time. Law of cooling refers to the relation which the velocities of equal successive periods bear to one another. The higher the temperature, other things being equal, the greater the velocity. If a body heated to 1000 lose 100 during the first second, Newton inferred that it would lose T Vf tne remainder, or 90, during the next second, 81* the next, 72.9 the next, and 65.6 the next. These numbers form a geometrical series, whose ratio is 1.111 ; and, though the law is not universal, it holds true, when the temperature is but a little elevated above the air. VII. Practical Application of the Laws of Conducted and Radiant Caloric. The material for windows should be a bad conductor of heat, as well as transparent ; hence glass is best adapted to the purpose. Glass also admits solar heat, while it prevents the escape of artificial heat. Double walls, doors, and windows, add to the warmth of buildings, because they confine between them a stratum of air, which, when not in motion, is a good non-conductor. Snow, furs, woollens, etc., are better non-conductors, because they enclose air. Stoves which are rough radiate more heat than those which are * The quantity of dew seems to depend also upon the difference be- tween the temperature of the atmosphere and that of the earth. 36 Effects of Free Caloric. polished. As the temperature of the human body usually exceeds that of the atmosphere, the object of clothing in cold weather is to retain the natural warmth ; and hence it is made of good non-conductors. In hot weather, clothing should conduct off the heat more freely. Also, under a hot sun, a black dress is more uncomfortable than one of light color. Many articles employed in the common uses of life are selected with reference to their conducting and radiating properties, as materials for furnaces, culinary apparatus, etc. Effects of Free Caloric. The phenomena which may be ascribed to caloric as an agent, and which may therefore 1 be classified as its effects, are numerous : some of these effects will now be enumerated. The most remarkable property of caloric, as we have seen, is the repulsion, which exists among its particles, by which it tends to an equilibrium, or to bring all substances to the same degree of temperature. This property enables it to penetrate all bodies, and, by its accumulation, to separate the integrant molecules from each other. It thus acts in oppo- sition to cohesive attraction ; hence it may be stated as a general law, that I. Caloric expands all bodies; liquids more than solids, and gases more than either. 1. Caloric expands solids. This may be shown by fitting an iron cylinder to an aperture, so that it will just slide through; heat it, and it will be too large to pass through. 2. Equal degrees of caloric expand some solids more than others. -This may be shown by an instrument called a pyrometer, or fire measurer. Fig. 8 represents this instrument. It is furnished with several rods, as iron, brass, copper, lead, and glass. BB, posts standing in A, and secured from spreading apart by the two bars CC. G, a thumbscrew, .passing through the post B, and entering one end of the rod D, holds it against a lever at the other end ; as the rod is heated, it expands and presses against the lever, which raises E, at the end of which is a cord passing up, over the hub of the index, and down Expansion of Solids. 37 again to the balance rod F ; E is raised by the expansion of the rod D ; F falls, drawing the cord, and giving motion to the hand. Fie. 8. The following substances, when heated from 32 to 212 Fahr., are elongated as follows: * its length. Flint glass, .... T2 V* Iron, .... ..V Copper, ..... Brass, ...... Lead . . . '. . . 3. Equal increments, or additions of caloric, at different temperatures, do not expand the same solid equally. That is, the expansion of a brass or iron rod will be much greater between 500 and 600, than between 100 and 200, or than between 200 and 300. The higher the tempera- ture, the greater the expansion, with equal additions of caloric. This results from the fact that the power of cohe- sion is constantly diminished, the farther the integrant parti- cles are removed from each other by heat. 4. The expansion of some solids is more uniform than others, with equal additions of caloric. The expansions of the more infusible solids are uniform within certain limits. From 32 to 122, their expansion is equal to that between 4 38 Expansion of Liquids. 122 and 212. But above 212, the higher the temperature, the greater the expansion, for equal additions of caloric. II. Caloric expands liquids more than solids. 1. This fact may be illustrated by heating a column of water in a glass tube, and an iron rod of the same dimensions, by a spirit lamp ; the water will rise in the tube, while the iron will scarcely be affected. The reason is, that the cohesive at- traction in liquids is nearly destroyed. Exp. Plunge a common thermometer into a jar of hot water, (Fig. 9.) The bulb of the thermometer will be ex- panded, and its capacity increased, but the mercury will be more expanded, and will rise in the tube. Fig. 10. 2. Equal increments of caloric ex- pand some liquids more than others. This may be illustrated by partially filling several glass tubes furnished with bulbs with different liquids, and placing them in hot water; as the liquids expand, they will rise to dif- ferent heights in the tubes, as shown in Fig. 10. 3. Equal additions of caloric, at different tempt <-raturrt t do not expand the same liquids equally. The same law holds here as in the case of solids the higher the temperature, the greater the expansion for equal amounts of heat; and those liquids also* which expand the least are more uniform within certain limits. Apparent exceptions to the general law .-.re found in the case of some liquids, near the point of con- gelation. Water expands by a diminution of temperature, and contracts by an addition of caloric, between the freezing point and 40 Fahr. III. Caloric expands gases more than solids or liquids. 1. The expansion of air may be shown by simply inverting a glass tube terminated by a bulb, and partly filled with water, (Fig. 11,) in a vessel of the same liquid : on heating the bulb, the air will expand, and expel the liquid from the tube ; or by holding a bladder partly Fig. 11. Expansion of Gases. 39 filled with air near the fire, the air will soon expand, fill the bladder, and even burst it.* 2. All gases, at any temperature, are expanded equally h :/ < (jual additions of caloric. In this respect, gases differ from solids and liquids. If, therefore, we can ascertain the expansion of one gas for a given number of degrees, we may know that of all others. The law of the expansion of air has been determined by Gay Lussac, who found that a given quantity of dry air dilates to ^bv of the volume it occupied at 32, for the addition of each degree of Fahr. Tluonj of Expansion. This has been already noticed. In the case of solids, the integrant particles are held together by cohesive attraction, but the caloric, being self-repellent, has the 'effect to overcome this force, and to separate the particles from each other. t In case of liquids, cohesive at- traction is much more feeble ; it will therefore require less power to separate the particles, and hence they are more expansible than solids. Gases are still less under the influ- ence of cohesion, and hence are more expansible. In fact, the form which matter assumes seems to depend upon the relative force of caloric and cohesion. In solids, cohesion preponderates ; in gases, caloric ; but in perfect liquids, these forces are in equilibrium, (the caloric being in a combined, and not a sensible state.) IV. Apparent Exceptions. Allusion was made to water and some other substances as apparent exceptions to the general law that heat expands and cold contracts all bodies. Water continues to contract, until it arrives at 39, and then begins to expand until congelation takes place. * So great is the tendency of air and other gases to expand, that, if a given portion be confined in a bladder, or in a very thin glass of a square form, and put under the exhausted receiver ofan air pump, the 5a:ne effect will be produced as when heat is applied; the particles of gases seem to be wholly free from the influence of cohesive attraction, and expand by their own caloric when the pressure is removed. t On the supposition that caloric is material, the effect is easily ac- counted for; but though &s particles repel each other, they must have a strong attraction fur matter, or they could not be introduced into it. Caloric, therefore, is the antagonist force to cohesive attraction, but possesses a powerful attraction for matter, peculiar to itself. 40 The Force of Expansion. Exp. Take a glass tube, with a bulb at one end, fill it with warm water, and place it in a mixture of salt and enow. The water in the tube will sink until it arrives at 39, and then begin to rise until it arrives at 32. The water, in becoming ice, will increase in bulk and ice, in melting, will diminish in bulk y^} hence, if the specific gravity of water is 10, ice will be 9. The maximum density of water is at 39 Fahr. V. The force of expansion, when water freezes, is very great. The Florentine academicians burst a hollow brass globe, whose cavity was only one inch in diameter, by freez- ing the water contained in it. This must have required a force equal to 27,720 pounds. Major Williams, in ITH-l-S, performed similar experiments at Quebec, by bursting bombs, which also illustrated the amazing force of water in the act of congelation. In consequence of this expansive force, glass and earthen vessels are broken, by suffering water to freeze within them ; water pipes are burst; pavements are thrown up, and de- .stroyed, and walls, especially in moist grounds, thrown down. Theory. The cause of this expansion is supposed to be due to crystallization. The particles, at 39, seem to be endowed with a kind of polarity, and attract the edges of each other ; and, at 32, they are arranged in ranks and files, which cross at angles of 60 and 120, as may be seen when water is freezing in a saucer. This new arrangement of the particles is supposed to increase the bulk ; but, whether this hypothesis be correct or not, it seems best to explain the effect.* VI. Advantage of this Exception. The wisdom and be- nevolence of God are strikingly exhibited in this arrange- ment. Otherwise, all our rivers, and lakes, and the ocean itself, in cold climates, would become solid masses of ice ! When a body of water is freezing, there are two currents * This hypothesis relieves us from the necessity of supposing a real exception to the laws of nature. The effect is due to the operation of another law, (crystallization,) to which the law of expansion gives place. For, after the crystallization is completed, the usual law pre- vails, and ice contracts, with the further reduction of temperature. Fis- sures are thus produced, in extreme cold weather, by the contraction of ice on ponds. Uses of the Law of Expansion. 41 established, as in the case of boiling water. The surface gives off its caloric to the air, and the particles become heavy, and sink down. - This forces the warm particles below to rise. But at 39 these currents are arrested, because the colder particles begin to expand, and remain at the top. As soon as they are frozen, a covering of ice prevents, in a great measure, the escape of caloric from beneath, and the process of freezing is greatly retarded. But, if the contraction ex- tended to the freezing point, the colder particles would con- tinue to fall to the bottom, until the whole should be brought to that point, and then suddenly freeze ; or, if they should freeze upon the surface, the ice would continue to sink down until the whole should become a solid mass. I fence, in coif climates, the rivers and lakes would be converted into solid ice, and all their inhabitants would be destroyed ! But, by this simple and beautiful arrangement, the ice is retained upon the surface, and confines sufficient stores of caloric to preserve the inhabitants of the waters, and render the coldest climates habitable by man. Water is not the only liquid which expands under the reduction of temperature; as the same effect has been ob- served in a few others, which assume a highly crystalline structure, on becoming solid. Hence the exactness with which cast iron fills the mould, and the use of antimony in casting types. Mercury is a remarkable instance of the re- verse ; for, when it freezes, it suffers a very great contrac- tion. VII. Practical Uses of the general Law of Expansion and Contraction. All kinds of machinery are, of course, affected by this' law. It must be strictly regarded in the construction of delicate time-pieces. Great use is made of it in the band- ing of wheels ; the iron is heated, and fitted to the dimen- sions, and then suddenly cooled, so that, by its contraction, it presses with great force, and becomes immovably fixed. In riveting together iron plates for steam engine boilers, it is necessary to produce as close a joint as possible. This is effected by using the rivets red-hot ; the contraction, which the rivet undergoes in cooling, draws the plates together with a force which is only limited by the tenacity of the metal of which the rivet itself is made. M. Molard, a few years since, at Paris, availed himself of this 4* 42 Thermometers. principle, to restore to their perpendicular direction two opposite walls of a gallery, which had been pressed outward by incumbent weight. Through holes in the walls, several strong iron bars wt-re introduced, so as to cross the apartment, with the ends projecting ; upon which strong iron plates were screwed. The bars were then heated, and, while hot, the plates were screwed up. On cooling, the bars con- tracted, and drew the walls together. By repeating this process several times, they were restored to their original position. Balloons were first sent up filled with air which had been expanded by heat. Winds. The phenomena of winds depend upon the expan- sion of the air by the heat of the sun. In this way the trado winds are produced. Land and sea breezes depend upon radi- ation and expansion. During the day, the earth is more heated than the water, and the air is more expanded, and rises up. This will produce currents-a-fl^pold air from the water to the land, % called sea breezes. During the night, the earth radiates caloric more rapidly than the water, the air be- comes cooler, and currents pass from the land to the water, which are called land breezes. Winds are also produced in those deserts which become greatly heated during the day. T/tcrmometers. But one of the most ingenious and useful applications of this law is to be found in the thermome- ter. Its invention is 'generally ascribed to Sanctorius, who flourished in the seventeenth century. Some ascribe it to Cornelius Drebel, and others to Galileo. 1. Air Thermometers. The substance employed by Sanctorius was atmospheric air, by the expan- Fig:. 12. sion and contraction of which he was enabled to (~} measure variations of temperature. His plan was very simple. The instrument consists of a glass tube, (Fig. 12,) open at one end, with a ball blown at the other ; enough of some colored liquid is poured in to fill half the tube, which is then in- verted in a vessel of the same liquid. The air in the bulb, by its expansion, causes the water in the tube to sink, and, by its contraction, the pressure of the atmosphere causes it to rise. By adapting a scale to the tube, the instrument is fitted for use.* On one account, air is the best substance for a thermometer, * This instrument is easily constructed by heating a glass tube in the fire, and blowing a bulb upon the end; then insert the open end in ome colored liquid. Differential Thermometer. 43 because its expansions and contractions are equal, with equal additions of caloric. But there are two objections to the use of this instrument ; it can be depended upon only when the barometer stands at a fixed point; variations of atmospheric pressure materially affect the rise or fall of the liquid. The expansion of gases, also, with slight degrees of caloric, is so great, that the length of the tube for measuring high or low temperatures would render the instrument inconvenient in practice. 2. Differential Thermometer. Sir J. Leslie, in 1804, con- structed a thermometer, in which air is used, which is not affected by atmospheric pressure. It consists of two glass balls, (Fig. 13,) joined together by a glass tube, bent twice at ri:_ r ht angles. The balls contain air, but the tube is nearly filled with sulphuric acid, CDlored with carmine. To one leg of this t'.i'x' is applied a scale It is evident that no effect will be produced upon the liquid, if both balls are heated alike, because the air in both will suffer equal expansion; but the slightest difference between the temperature of the two balls, will instantly be indicated by the rise or fall of the Kquid in the tube. Hence its only use is to detect slight variations of tempera- ture between two substances, or of two contiguous spots in the same atmosphere, in very delicate experiments, where caloric is reflected, or refracted to a focus. It is hence called the Differential Thermometer. A much more delicate instrument of this kind has been constructed by Dr. Howard, of Baltimore, in which the vapor of ether, or alcohol, in vacua, is used instead of air. But if air expands too much, and is affected by pressure, so as to be unfitted for the common purposes of measuring the degrees of temperature, solid substances, on the other hand, expand too little. The substance most convenient is a liquid, and the object is, to find some liquid whose dilations are nearly equal with equal additions of caloric, and whose boiling and freezing 44 Mercurial Thermometer. f points are removed at the greatest distance from each other. Alcohol and ether would answer this purpose very well in one respect, they resist congelation to a very low tempera- ture, but boil much sooner than water. Mercury seems to be the only substance which will answer the necessary condi- tions. 3. Mercurial Thermometer. This instrument Fig. 14. (Fig. 14) is constructed in the following manner : A tube is selected with a small bore, of uniform diameter, and a small ball is blown at one end. The,air is then mostly expelled from the bulb, by holding it in a spirit lamp, and the end of the tube quickly inverted in a cup of clear, dry mercury. As the bulb cools, the atmosphere forces the mer- cury into the bulb, which fills it two thirds full ; the bulb is again heated, and the mercury rises up, nearly filling the tube, and expelling the air. It is again inverted over mercury, when the bulb and one third of the tube are filled ; it is then heated until it boils, and fills the tube to the top. A fine (lame is then darted from a blowpipe * upon the open extremity of the tube^ so as to fuse the glass, and clo;je the aperture before the mercury recedes. It is then said to be her nut i- cally sealed, and the space abandoned at the upper extremity of the tube, as it cools, is a vacuum. N. Graduation. This is effected by ascertaining two fixed points ; and, as water always freezes at the same temperature, and also boils at tin- same temperature, when the barometer stands at the same height, we have only to immerse the bulb and a part of the stem in melting snow, or water containing ice, and mark the point to which the mercury sinks. This is the freezing point. To fix the boiling point, distilled water should be used, and the barometer should stand at 30 inches. A small quantity of the water, not more than one inch in depth, and contained in a deep metallic vessel, is made to boil briskly, and the point to which the mercury riees, is marked ; this is the boiling point. These two points being fixed, the interval is variously divided into equal parts. Fij? * Fig. 15' represents the most common forms of the blowpipe. It consists of a brass or Copper tube, tapering nearly to a point, through the small end of which the air is forced, either by placing the large end in the mouth, or by adapting to it a pair of bellows. Register Thermometer. 46 Newton first suggested a scale, in which the zero was placed at the freezing point, and the interv.il divided into 40 parts, or degrees. In Fahrenheit's thermometer, which is generally used in this country and in England, the zero is placed at 32 below the freezing point, and the interval between the freezing and the boiling points is divided into 180 parts, so that the boiling point of water is 212. Fahrenheit fixed his zero by immersing the thermometer in a mixture of snow and salt. Reaumur's scale places the freezing point at zero, and the boiling at 80. De Lisle placed the boiling point at zero, and the freezing at 150 below ; this is used in Russia. But the most convenient scale is that of Celsius, in which the freez- ing point is at zero, and the boiling at 100, called the Centigrade thermometer; this is used in France. The different scales are seen in Fig. 16. The scale is either marked on the tube by a diamond, or on ivory or paper, and at- tached to the tube. The degrees above the boiling and below the freezing points occupy o(ju;il spaces w-th those between these points. The temperature expressed by one scale can be reduced to that of another, by knowing the relation which exists between their de- grees. The lower part of the scale, in labo- ratory thermometers, (Fig. 14,) turns up by a hinge, so that the bulb can be immersed in corrosive liquids. Fig. 10. J Fahrenheit. | Centigrade. J Reaniniir. Tl J De Lisle. 710- Jt _ *<> " = 90 ;,' [0 : -. : ,_, . Go I /'j - 50 140 " * ;o - GO _ MO- 76' ; BO- r-40 .90- loo- to 80- ;i y.j- 70 1.^0 12D-- 60 C(V tin Tff U; '-, - _ V ~ - Q _r, -- _ : - 10 R 55 r - - Fig. 17. 4. Register Yjfurmomfter, This instrument consists of two thermometer tubes, (Fig. 17,) bent at right angles, and retaining a horizontal position. One tube contains alcohol, and the other mercury. A small piece of black enamel is placed in the tubes on the surface of each liquid. As the alcohol contracts by exposure to cold, the enamel follows it towards 46 Pyrometers of Wedgwood and Daniell. the bulb ; but when it expands, the enamel remains stationary, and steers the liquid to pass by it. When the mercury con- tracts, the'enamel does not follow it; but when the mercury expands, it is forced along. Consequently, it remains at the highest temperature. The -enamel, in the tube of alcohol, will indicate the lowest, and that in the tube of mercury the highest, temperature during any given time. For measuring temperatures below 39 F., the freezing point of mercury, alcohol, or ether, must be employed ; for temperatures above 662, no liquid can be used, as they are all either decomposed, or dissipated in vapors. For very high temperatures, therefore, some of the more infusible solids are used. The instruments for this purpose are called Pyrometers. This term is derived from two Greek words, signifying measurer of fire. 1. Pyrometer of Wedgwood. This is founded on the property which clay possesses of contracting when strongly heated, without expanding when cooled ; but the indications of this instrument cannot be relied on, and it is seldom used. 2. Pyrometer of Danidl. This instrument, the best now in use, consists of a bar of platinum enclosed in a case 7J inches in depth, made of black lead : one end of the bar is fixed ; the other is made to move an index, as it is heated. This, however, is not perfectly accurate, owing to the greater expansion of the platinum, in high temperatures, with equal degrees of heat. Generally, these instruments depend upon the elongation of a metallic bar by heat ; and one of the best for illustration is described on page 37. 3. On the same principle is the Metallic Thermometer of Brequet, (Fig. 18,) for temperatures between the freezing and boiling points of water. It consists of a slip of silver and one of platinum, united face to face with solder, and coiled into a spiral, r/, one end of which, c, is fixed, while the other is connected with an index, e, which moves over a circular, graduated plate, f, f. This index is found to move over equal spaces with equal additions of caloric; and so sensible is it to slight Fig. 18. Insensible Caloric. 47 variations, that when enclosed in a large receiver, which was rapidly exhausted by an air pump, it indicated a reduc- tion of temperature from 66 to 25=: 41, while a sensible mercurial thermometer fell only 36. It will be readily seen that thermometers do not give us the absolute, but only the relative quantity of caloric con- tained in bodies. The true zero, or that point where abso- lutely no caloric exists, is unknown. Some have conjectured that it is 1200 or 1400 below the freezing point of water. But it is mere conjecture ; nor is it known, on the other hand, how high a temperature might result from an accumulation of heat. Neither limit is known. The thermometers and other instruments measure only a few degrees, in the middle of a scale, whose extremities are indefinitely extended. SECT. 2. INSENSIBLE CALORIC. Every one sees that a quart of water contains double the quantity of caloric which is contained in a pint of the same liquid, when the temperature of both is the same. This is called insensible caloric, because ij does not affect the ther- mometer. Specific Caloric. But different quantities of caloric are required to raise equal weights of different substances to the same temperature ; and, conversely, different quantities arg given out by them in cooling equally. Suppose, for example, that, on adding a given quantity of heat to a pound of water at 50, the temperature will become 60, the addition of the same quantity to a pound of sperm oil at 50, will raise the temperature to 70, while a pound of pcftvdered glass will be raised from 50 to 100 by the same quantity of caloric. The temperature is increased 10, 20, and 50, in these dif- ferent substances; i. e., if the required temperature to which they shall be raised be given, the oil will require but half as much heat as the water, and the glass only one fifth as much. Specific heat is the relative quantity of caloric requisite to raise the temperature of substances equally; i. e., taking water for a standard at 1, the specific heat of sperm oil will be -fo> and of powdered glass T 2 ^.* * The phrage capacity for caloric was formerly used, and was in- 48 Methods of determining Specific Heat. In these experiments, a portion of caloric disappears. This portion has been called latent or combined caloric, in reference to the theory mentioned in the note below The phrase insensible heat is preferred, as not involving any theory. Methods of determining Specific Heat. Various methods have been employed to ascertain the specific heat of sub- stances. The most convenient method is to mix with the substances, all being at the same temperature, a given quantity of some liquid, as water, at some other given temperature, and observe the relative effects. Thus, as in the example given, a pound of water at 80 may be added to a pound of the same at 50, and the resulting temperature will be the mean, 65 ; another pound of water at 80 to a pound of oil at 50, and the resulting temperature will be 70 ; i. e., the oil will gain 20 while the water loses but 10 ; and ajra'm, ;i pound of water at^80 to a pound of glass at 50, and the temperature of the mixture will be 75, the glass gaining 25 by 5 loss of the water. Other and more difficult experi- ments are necessary to ascertain the specific heat of gases and of solid bodies. Laws of Specific Heat. The principal laws of specific heat are the following : 1. At the same temperature, and, in the case of gases, with the same pressure, the specific heat of each body is constant. 2. The higher the temperature, and, in the case of gasrs, the less the pressure, the greater the specific heat of the same body. This is supposed to be owing to expansion. In gases, the specific heat varies with the density and elasticity ; the greater the density, the less the specific caloric ; and the greater the elasticity, the greater the specific caloric. 3. A change of form is accompanied by a change of spe- cific cidoric. The specific heat of a body, as it passes from a solid to a liquid state, is increased. It is also supposed to tended to convey the idea, that a portion of the heat enters into and is combined with substances in a latent state ; but this is hypothetical, and the phrase specific heat is preferred, as involving merely a fact. Effects of Insensible Caloric. 49 be increased by a change of the body from a liquid state to that of a gas or vapor. 4. As each substance has a specific heat peculiar to itself, it follows that a change of constitution is accompanied by a change of specific heat. 5. A change of specific heat is generally accompanied by a change of temperature. Thus the expansion of a gas, which increases its specific heat, diminishes its temperature. As a practical inference from the doctrine of specific heat, it may be remarked, that much less fuel will be necessary to heat some substances than others. Effects of Insensible Caloric. These are liquefaction and vaporization.* I. LIQUEFACTION. All bodies exist in one of three states, solid t liquid, or gaseous, and their forms seem to depend, as we have seen, (page 39,) upon the relative forces of cohe- sion and caloric. Hence, by the increase and diminution of either of these forces, we can cause the body to assume either of these states. If a solid be sufficiently heated, it will become liquid, and then gaseous. So general is this fact, that it may be stated as a law. 1. Point of Liquefaction. The temperature at which liquefaction takes place, is called the melting point, or point offitfion t as that at which liquids solidify is termed the point of congelation. These points are identical; but there is a very great difference in substances as to the degree of heat which is required to fuse them. Each substance has a fixed point effusion and of congelation. 2. Caloric of Fluidity. If a pound of ice, which is at 32, be melted in a pound of water at 172, the temperature of the whole will not be at the mean of 102, but at 32, showing that 140 have been taken into a latent state, by the liquefaction of the ice. Generally, liquefaction is accom- * Classed as effects of insensible caloric, because the free caloric passes into an insensible state, which is essential to the process. 5 50 Caloric. Freezing Mixtures. panied by the conversion of free into insensible heat. The heat which thus disappears seems essential to the process of liquefaction, and is called the caloric of fluidity. Its quantity varies in different substances, as in the following table : Ice . . , 140 Fahr. Beeswax . 175 Fahr. Sulphur . 143.68 " Zinc . . 490 Spermaceti 145 " Tin . . 500 Lead . . 162 " Bismuth . 550 It fine. When the process is reversed, in congelation, this insensi- ble caloric is thrown out. in a free state. Thus the freezing of water produces heat. 3. Freezing Mixtures. Liquefaction may be produced without the addition of heat, and hence the caloric of fluidity will be obtained, in part, from the temperature of the sub- stances melted, but chiefly from the surrounding bodies ; ;i great degree of cold is thus often produced. On this princi- ple varioys freezing mixtures are contrived. The most com- mon method of producing cold is, to mix together eqiuil quantities of fine salt and fresh fallen snow, or pounded ice. The salt melts the snow by its affinity for water, and the water dissolves the salt, so that both are liquefied. The drjrrer of cold produced is 32 below the freezing point of water, or at zero. This led Fahrenheit to commence his si -ilc ;it that point. Any other substance, which has a strong affinity for water, may be substituted for salt. The crystallized chloride of calcium is the best, because it produces the most rapid liquefaction. The following table, constructed by Mr. Walker, contains the proportions of several substances to produce different degrees of cold. Dep. of Cold produced. MIXTURES, ft v P Weiht f Thermometer sinks Sea-salt . ;' , , ; 1 ) . , . to 5 Snow . . . ; 2 J Sea-salt 2) Muriate of ammonia . 1 > ' < V^. to 12 Snow 5 } Sea-salt 5 \ Nitrate of ammonia . 5 > . . . to 25 Snow 12 ) Diluted sulphuric acid 2 ) Snow 3 } from + 32 to 23 55deg. Freezing Mixtures. 51 Concentrated muriatic acid 5 J froM + 330 to _ 2r ^ deg Concentrated nitrous acid 4 from 4. 33 to _ 30 62 Snow ...... 7 ) Chloride of calcium . . 5) from + 32 o to _ 40 72 Snow ...... 4 J Snow P taSSa ' *om+32to--5l 83 Freezing may also be effected by the rapid solution of salts. The following table exhibits the proportions, taken from Walker's essay in the Phil. Trans. 1795. The salts must be finely powdered and dry. MIXTUIKS. Thermometer*,* Muriate of ammonia ..51 Nitrate of potassa . . 5 > from +50 to + 10 40 deg. Water ...... 16 ) Watef ^ amm nia 1 I fr m + 5 l + 4 4G Nitrate of ammonia . . 1 | Carbonate of soda . . 1 > from -f- 50 to 7 57 Water ...... l) Sulphate of soda . . U rom + 50 to -- 3 .53 Diluted nitrous acid . . 2 ) Sulphate of soda . . . 6| Nitrate of ammonia . . 5 > from -|- 50 to 14 64 Diluted nitrous ncid . . 4 ) Rhosphate of soda . . | from + 50 o to _j 2 o 02 Diluted nitrous acid . 4 J Phosphate of soda . . 9 | Nitrate, of ammonia . 6 > from -f- 50 to 21 71 Diluted nitrous acid . . 4 J Sulphate of soda 8 ) c Mariaticacid .... 6 } from + 50 to 50 Sulphate of soda . 5 I f Q0 y Diluted sulphuric acid . 4 ^ In order to the greatest effect, the substances should be cooled in a freezing mixture before they are united. 4. The degree of cold produced by these artificial pro- cesses, is limited. The greater the difference between the temperature of the air and that of the mixture, the more rapidly will the air communicate caloric to it; and this soon 52 Vaporization Ebullition. puts a limit to the degree of cold. According to Mr. Walker, the greatest cold did not exceed 100 below the zero of Fahrenheit. But a more intense cold is produced by evapo- ration. 5. No process, however, will deprive a body of all its caloric. Dr. Irvine has attempted to infer the absolute amount from the specific caloric of bodies ; thus ice contains T \j Jess specific caloric than water; and, as this T \y is equal to 140, it is inferred, that water contains ten times the amount, or 1400 of caloric ; but the estimates made by different chemists vary from 900 to 8000, which shows that but little confidence can be put in their calculations. II. VAPORIZATION. By vaporization is meant the conver- sion of liquid and solid substances into vapor. It is generally supposed that, if sufficient caloric be applied, all substances are susceptible of this change. A gas differs from a vapor in the circumstance that it is not so easily condensed into a liquid ; it retains its state at ordinary temperatures and pressures. " The only difference between gases and vapors is the relative forces with which they resist condensation." T. Some substances yield vapor readily, and are called vola- tile. Others sustain the strongest heat of furnaces, without volatilizing, and are hence said to bejixed in the fire. This difference seems to depend on the relative forces of cohesion and caloric. Liquids are more easily vaporized than solids; and solids, with a few exceptions, like camphor, assume the liquid state before they are converted into vapor. Liquids may be vaporized in two ways: 1. by ebullition ; 2. by evaporatibn. In the first case, there is a rapid produc- tion of vapor, causing commotion in the liquid; and in the second, the process is conducted silently, the vapor impercep- tibly passing off from the surface of the liquid. Ebullition. 1. Boiling Point. The temperature at which a liquid is converted by ebullition into a vapor, is called its boiling point. This point varies greatly in different liquids under the same circumstances, and in the same liquid under different Ebullition. 53 degrees of pressure. But each liquid has a fixed boiling point, when all the circumstances are the same. 2. The chief circumstance which modifies theJooiling point of the same liquid, is the pressure of the atmosphere. A column of air, extending to the top of the atmosphere, presses upon every square inch of surface with a force equal to 151bs. This is sufficient to sustain a column of mercury 39 inches, or a column of water 34 feet. But the pressure varies at different times on the surface of the earth ; and as we ascend high mountains, the pressure diminishes rapidly. The instrument by which this variation is measured is called the Barometer, the principle of which may be illustrated by filling a glass tube, open at one end, and about 33 inches long, wfth mercury, and inverting the open end in a cup of the same liquid. (See Fig. 19.) The pressure of the atmos- phere on the surface will sustain the mercury in the tube to the height of from 27 to 31 inches. When the barometer stands at 30 inches, ether boils at 96, alcohol at 176, water at 212, and mercury at 662, F. If the barometer stand at 28 inches, all these substances will boil at a lower temperature, and if it rise to 31 inches, the boiling points will be raised. Hence the two following laws : 1 . As the pressure on the surface of liquids diminishes , their boiling temperatures diminish. Thus water heated to 72, and placed under the receiver of an air pump, will boil, on exhausting the air, if the temperature be preserved. Ether will boil violently, under an exhausted re- Fig. 19. ceiver, at the common temperature of the atmos- phere. Exp. 1. Fill the barometer tube a with mercury, (Fig. 19,) and invert it in a cup c of the same liquid ; then introduce a. small quantity of ether. As soon as it reaches the vacuum r, it boils rapidly, and the vapor forces the mercury down the tube. Fig. 20. Exp. 2. The pulse glass (Fig. 20) acts on the same principle. It is con- structed by blowing a bulb b on the end of a glass tube, in which a small open- ing is made, and through this a similar 54L Influence of Pressure, upon the Boiling Point. buH^ a is blown on the other end. Some spirits of wine are now in- troduced, and heated in the closed bulb a until the vapor escapes from the aperture in 6, when it is hermetically sealed. The heat of the hand upon eer bulb is sufficient to cause violent ebullition. Etheflboils in vacuo at 44, alcohol at 36, and. water at 72, an(} liquids generally boil at temperatures 140 less in vacuo thar^at the common pressure. It is owing to this fact, that intense cold can be produced by boiling ether in vacuo. Water, and even mercury, under favorable circumstances, may be frozen. To render the experiment successful, there should be sulphuric aci3 in the receiver to absorb the vapor of ether, which, by its pressure, would otherwise soon prevent the ether from boiling. 2. As the pressure on the surface of liquids increases, their boiling temperatures increase. When water is heated to the temperature of 212, its force upon each square inch is equal to 15 Ibs. As this is equal to the pressure of the atmosphere, it will, at this temperature, escape in vapor; hence it cannot be heated in the open air above this point. But if the pres- sure be increased sufficiently, it may be heated to any extent, without exhibiting the phenomena of ebullition. Fig. 21. Exp. Boil water in a Florence flask, (Fig. 21,) and cork it tight ; the ebullition will instantly cease, because the steam formed will press upon its surface ; but by pouring on cold water, and condensing the steam, it will boil violently; pour on warm water, ana it will stop boiling. This is a convenient mode of illustrating both of the above laws : as the pressure is increased by the formation of steam, the boiling point is raised, while it is lowered by condensing the vapor and diminishing the pressure. This is called the culinary paradox. But, in order to exhibit the influence of pressure upon the boiling point, we must employ a strong metallic boiler, called a digester, which consists simply of a strong boiler furnished with stop-cocks and valves, and an apparatus to ascertain the temperature and pressure. Water confined in this boiler may be heated to a very high temperature without boiling ; but the steam which will be formed will endanger the boiler, before we can ascertain its greatest expansive force or pres- sure upon the liquid. Marcet's Digester. 55 For experiments on the pressure of Fig. 33. steam, Marcet's digester (Fig. 22) is well adapted : a is a strong brass globe, into which a portion of mercury is poured, and then half filled with water; 6 a ba- rometer tube passing through a steam- tight collar to the bottom of the globe ; c is a thermometer graduated to 400 or 500 ; d a stop-cock ; e a spirit lamp ; * andy a brass stand, upon which the whole is supported. Upon the stop-cock d a j^team gun may be screwed. When heat is applied, the pressure is measured by ( the height to' which the mercury rises in the tube 6, and the temperature is ascer- tained at the same time by the thermome- ter c. On the application of heat, as soon as the water boils, the thermometer will stand at 212, and the pressure, of course, will be equal to one atmosphere, or 15 Ibs. to the square inch. As the temperature increases to 217, the pres- sure will elevate the mercury 5 inches, and at 242 about 30 inches, each degree of temperature raising the mercury about one inch. Absorption of Free Caloric in Ebullition. When water is converted into steam, a great quantity of sensible heat is taken up into a latent state ; which, on condensation, again appears in a free state. If, for example, steam at 212 sufficient to form one pint * The spirit lamp is very useful for pro- ducing heat in the laboratory. It consists of a small glass lamp a, (Fig. 23,) the wick of which passes through a metallic collar c; b is an extinguisher, to prevent the wick from absorbing water when not in use. It is filled with alcohol, which burns in the same manner as oil, but does not yield any smoke. A common glass or tin lamp will answer a very good, purpose, using alcohol instead of oil. Fig. 33. a 56 Steam. of water, be condensed in ten pints of water at 117, the temperature of the whole will be 212; the ten pints will be elevated 95 : this is equivalent to raising the temperature of one pint 950. The latent heat of steam is, therefore, 950 ; other substances are subject to the same law. Hence it may be stated generally, that, in ebullition, he.at is taken into a latent state, and given out on condensation. The latent heat of different vapors is various, as may be seen in the following table: Latent Heat. Vapor of water at its boiling point . . . 967 Alcohol V . ; . . : \ > . . 442 Ether 302.379 Petroleum . . .'' . '. . . 177.87 Oil of turpentine . ;:'' V . . 177.87 Nitric acid .". j .;!". . 531.99 Liquid ammonia . . . . . 837.28 Vinegar '-. '.;"..''.. . 875 Steam is formed, ordinarily, by ebullition. At the moment when water takes the state of vapor, in the open air, it has an expansive force equal to one atmosphere, or 15 Ibs. on the sq. inch. If, then, it be disconnected from water, its laws of expansion ad contraction, at all temperatures above 212, are the same as all gaseous bodies. Equal increments of caloric expand it equally, and its expansion is in the ratio of the heating power; for every degree of Fahrenheit's ther- mometer, it expands ^fa of what its volume would be at 32, if it did not condense. It may be heated, like any gas, until it is red hot, if the vessel is sufficiently strong. But steam is usually formed in the boiler where water is present, and, as the temperature increases, fresh portions of steam are con- stantly added to that which is already formed, so that its expansive force increases in a much more rapid ratio. According to the experiments of Dulong and Arago, if we take atmospheric pressure for unity, we shall find the pres- sure of steam at 233.96, equal to 1 j atmospheres. 250.52 equal to 2 atmospheres, or 301bs. to the sq. inch. 275.18 " 3 " 45 320.36 " 6 " 90 " Uses of Steam. 57 374 equal to 12 atmospheres, or 1801bs. to the sq. inch. 435.56 " 24 " 360 " " 486.59 " 40 " 600 510.60 " 50 " 750 " When steam, at a high temperature, is condensed in cold water, a loud, crackling noise is heard, which is due to the collapse of the water, a vacuum being formed by the sudden condensation of the steam. Ezp. Let a jet of steam rush from the digester through a pipe into cold water. When liquids are converted into vapor, under high pres- sure, the vapor is very dense. If, then, it is allowed to escape from the orifice of the boiler, the hand may be held at a short distance without being burned, though the temperature of the steam, before it escapes, is several hundred degrees. This is due to its expansion, and the consequent absorption of its sensible caloric. When water is converted into steam at 212, it absorbs 950 of caloric. If now it be condensed to 32, it will give out 950 of latent, and 180 of sensible caloric^ 1130. Now, if we take the same weight of steam, at a higher temperature, 250, and condense it to 32, it will give out 912 of insensible, and 218 of sensible caloric = 1130; hence the sum of the sensible and insensible caloric contained in equal tonights of steam, is exactly the same at all temperatures =. 1 130. The absorption of caloric seems to perform a similar office in vaporization and liquefaction, being essential both to the formation of vapors and of liquids. Application of Steam to practical Purposes. 1. It is used for warming- rooms. For this purpose it is conveyed in pipes, and continues to heat the room until its caloric is nearly exhausted. It is then condensed to water, and gives out its latent caloric. Every cubic foot of steam in the boiler will heat 200 feet of space to 70 or 80 ; and each square foot of steam pipe will warm 200 cubic feet of space. It is used for heating water-baths and dyeing-vats; for 58 Caloric. Steam Engine. bleaching cloth; for producing a vacuum by its condensa- tion; for various culinary purposes; also, for .drying various substances, such as muslins, calicoes, gun-powder, etc. 2. But its most important application i? to the propelling of machinery : the instrument employed for this purpose is the steam cngint; the invention ef which is due to Capt. Savery. The principle of his invention may be illus- trated by a tube, with a bill blown at one end, (Fig. 24): fill this with water, and invert it in the same liquid ; apply heat to the bulb, and, as soon as the water is at 212, steam will be formed, and force the water out ; but, as soon as the steam comes in contact with the cold water in the vessel, it is suddenly condensed; a vacuum is formed, and the atmosphere forces the water with great violence up the tube, so as to fill the bulb. If a piston be fitted to the tube, it will constitute the instrument devised by Dr. Wollaston, except that the steam in his apparatus is con- densed by putting the bulb into cold water. The atmos- phere presses the piston down, while it is raised by causing the water in the bulb to boil. The moving power of the steam engine is the same as in this apparatus, but the steam is condensed in a separate ves- sel called the condenser : this constitutes the improvement of Watt, by which means, the temperature of the cylinder is never below 212 Fahr. 3. The steam generator of Mr. Perkins sustains a pres- sure of 800, 1000, and even 15001bs. on the square inch. The steam is then so hot as to set fire to tow, and even ignite the generator at its orifice. At this very high temperature, it is about half as heavy as water. It is a remarkable fact, that, at such pressures, the steam will not rush through a small aperture, through which it will rush with great violence, and a roaring noise, when the temperature arid pressure are diminished. Mr. Perkins thinks that 400 atmospheres, or 6000 Ibs. to the square inch, is the maximum of pressure; i. e., that under this pressure, water will remain liquid at any temperature, even at a white heat. The boiler of the gener- ator is small, and not more than a gallon of water is used at a time. Evaporation. 59 Steam Artillery. Mr. Perkins has succeeded in applying this amaz- ing force to the propelling of cannon balls. He states that sixty 41b. balls can be discharged in a minute, with the accuracy of a rifle musket, and to a proportional distance. A musket may also be made to throw from one hundred to a thousand balls per minute. It is great- ly to be hoped that his experiments will prove successful ; for, if such engines of death could be brought into the field of battle, few nations would be willing to settle their disputes in that way. Few would fight in the prospect of certain death. Fig. 25. Distillation. This process is conducted by converting liquids into vapor, which passes into a long, metallic tube, or worm,sur rounded by cold water. The va- por is condensed, and the liquor runs off at the opposite extremity of the tube. Fig. 25 represents this apparatus ; a a copper boiler, 6 its head, connected with the worm, which is coiled in the refrigerator d. The vessel d is filled with cold water to condense the vapor in the worm as it passes through it. Evaporation. The only difference between evaporation and ebullition is, that the one takes place quietly, and the other with the ap- pearance of boiling. Evaporation takes place at all temper- atures, but ebullition at fixed temperatures. The former takes place, not only in all liquids, but in many solids, as camphor; the latter is confined to liquids. 1. Evaporation is much more rapid in some liquids than in others, and it is always found that those liquids whose boiling points are lowest evaporate with the greatest rapidity. Thus alcohol, which boils nt a lower temperature than water, evaporates also more freely, arid ether, whose point of ebullition is yet lower than that of alcohol, evaporates with still greater rapidity. Also, if the temperature of the liquid be raised or lowered, the evaporation will be more or less rapid. 2. Increase of pressure checks evaporation, and diminution of pressure promotes it ; thus water will evaporate much more rapidly in a vacuum. 60 Caloric. Uses of Evaporation. This is precisely what we should expect from the fact just mentioned, that evaporation is most rapid in liquids whose boiling point is lowest; for the diminution of pressure lowers the boiling point. From the three facts which have been mentioned, it may be inferred that evaporation is more rapid as the distance between the boiling point and the tttn- perature of the substance diminishes. The other circumstances that influence the process of evaporation are, 3. Extent of Surface. As evaporation goes on from the surface, it is evident that, the greater the extent of surface, the more rapid the evaporation.' 4. State of the Atmosphere. If the atmosphere be already saturated with moisture, evaporation will be checked ; or, if the air remain still, it will soon become saturated, and the evaporation is promoted by the motion of the air. 5. Absorption of Free Caloric by Evaporation. If a dish of water be placed in the exhausted receiver of an air pum]>, and another, of sulphuric acid, to absorb the vapor of the water, the water will evaporate so rapidly, as to be frozen by the absorption of its sensible caloric.* Hence the cffcit of evaporation is to produce cold ; because the sensible caloric passes into an insensible state. Exp. This may be further illustrated by filling a small glass tube with water, and surrounding it with cotton wool. If the cotton wool be soaked with ether, and a current of air, from a common Iwlluws, In- directed upon it, the water, in the course of a few moments, will congeal. Exp. A very satisfactory experiment is performed with the cryophorus, an in- . Fig. 26. strument invented by Dr. Wollaston. * - - - - It consists of two glass balls, (Fig. 20,) %/^\^ ~?\ connected by a glass tube. Both balls \N=^ are free from air ; but one of them con- jF^ tains a portion of distilled water. When the other ball is placed in a freezing mixture, so as^ to condense the watery vapor as fast as it formed, the evaporation is so rapid from the * The most intense cold which has been produced is the effect ot evaporation. If a large quantity of carbonic acid gas be condensed into a liquid by pressure, and suffered to escape through a small aper- ture, it will congeal by its own expansion ; the solid acid thus formed will evaporate so rapidly in a vacuum, as to produce the cold of 13(> Fahr. At this temperature, the strongest alcohol becomes viscid, and common alcohol becomes frozen. Uses of Evaporation. 61 surface of the water in the other ball, as to freeze it in two or three minutes. 6. Cause of Evaporation. The cause of evaporation is, doubtless, the same as that of ebullition caloric; although some have attempted to account for it on the supposition of an affinity between the air and the evaporated liquid ; but evaporation in a vacuum is fatal to this hypothesis. 7. Uses of Evaporation. It is well fitted for cooling apartments. All that is necessary for this purpose, is to sprinkle the floor with water. It moderates the he;it of warm climates; hence places near large bodies of water are cooler in the summer than those more remote, and the greater the heat from the sun's rays, the more rapid the evaporation, and of course the greater quantity of sensible caloric goes into an insensible state. Evaporation not only takes place from the surface of water, but from the surface of the earth, and from plants and ani- mals: hence it tends to defend the animal, as well as the vegetable system, from external heat. When an animal is exposed to external heat, perspiration commences over the whole surface, and the liquid, in passing to a vapor, absorbs the sensible caloric. On this principle firo-kings subject themselves to a high temperature, with but little inconve- nience. The oven girls of Germany, also, often expose them- selves to a temperature of from 250 to 280, and one girl breathed five minutes in an atmosphere of 325. In these cases, water boils rapidly, and beef-steak is cooked in a few minutes. If, however, the air be moist, or the body be varnished, so as to prevent perspiration, the heat cannot be sustained for a moment. The heat produced by violent exercise is carried off in the same manner. But the vital principle, doubtless, has much to do in forti- fying the system against the extremes of heat and cold ; for, although men may be subjected to a range of temperature of more than 400, from 350 above to 75 or 80 below zero, -the temperature of their bodies does not vary five 6 62 Caloric. Hygrometers. degrees, but remains stationary at 98 and 100, during a/I the varieties of external temperature. Evaporation often fills the air with deadly miasma. The fever and ague is supposed to be produced in this way. Con- siderable effect is also produced upon the bulk of gases, and it becomes a point of great interest to ascertain the amount, especially when delicate experiments are to be performed. The atmosphere, of course, always contains a portion of watery vapor. At the freezing point it contains f\^ of its volume, and the higher the temperature, the more vapor is it capable of sustaining. The instruments for measuring the amount of vapor in the air, and other gases, are called Hygrometers. These vary in form, but may ail be reduced to three principles. 1. TMie first is founded on the property of some substances to elongate when placed in a moist atmosphere, and to con- tract when dry. The human hair possesses this property in an eminent degree, and is the substance employed by Saus- sure. 2. The second kind of hygrometer depends on the rapidity of evaporation, the temperature and pressure being the same; the more vapor there is in the air, the slower will the process go forward. Leslie's hygrometer is constructed on this prin- ciple. 3. The third kind depends on the fact that, if a cold body be introduced into moist air, the moisture will condense on it; as is sometimes seen on the surface of glass and earthen vessels filled with cold water, and is an indication of rain. The temperature at which the moisture is condensed is called the dew point. Application of the Laws of Insensible Caloric to the Explana- tion of Natural Phenomena. 1. We have seen that, when solids are converted into li- quids, they absorb large quantities of caloric. Hence the process of thawing, contrary to the common belief, is a freezing process. Ice, in becoming water, absorbs 140 of sensible caloric ; hence countries surrounded by water are Explanation of Natural Phenomena. 63 cooler in the spring than those where less ice is formed dur- ing the winter. 2. Liquids, in passing to vapors, absorb sensible caloric. In the vaporization of water, nearly 1000 of caloric are ab- sorbed. It is therefore a much more powerful cooling pro- cess than the liquefaction of ice; hence the heat of warm countries is greatly reduced by the constant formation of vapor. This is the reason why the transition from the cold of winter to the heat of summer is not sudden, but gradual ; the ice and the water cannot obtain caloric in sufficient quantities to convert them into vapor. 3. When vapors and gases become liquids, they give out large quantities of caloric; hence it is usually warmer after a rain, a large quantity of caloric being evolved by the con- densation of the vapor in the atmosphere. If, nowever, the earth is dry and hot, the heat converts the water into vapor, and renders the air cooler. 4. Liquids, in becoming solids, give out caloric; hence the process of freezing is a heating process. To prevent some substances from freezing, we have only to place them near those which congeal at a higher temperature; thus water placed in a cellar will prevent vegetables from freezing, because they require a lower temperature than water to freeze them ; before they reach the point of congelation, the freezing of the water renders its insensible caloric sensible, and prevents them from attaining it. By the process of converting water into ice, a process constantly going forward when the thermometer stands at 32 Fahr., large quantities of caloric are thrown off into the itmosphere ; hence the shores of a country are warmer in the winter than the interior ; hence, too, the approach of the cold season is gradual, the greatest degree of cold rarely occurs till after the winter solstice, twentieth of ^December. Were these laws suspended, September and March would be of equal temperatures. June would be the warmest, and December the coldest month in the year. 64 Caloric. Sources of Caloric. SECT. 3. SOURCES OF CALORIC. The principal sources of caloric are, 1. The sun. 2. Chemical action, including electricity, galvanism, and combustion. 3. Condensation by mechanical action, including percus- sion and friction."" 4. Vital action. 1. Sun. The heat produced by the sun varies with the kind and color of the surface, according to principles already noticed. The temperature produced by their direct action is seldom more^than 120 ; but, when the rays are concentrated by means of convex lenses, or concave mirrors, a very intense heat is produced. Lenses have been constructed concen- trating sufficient heat to melt some of the most refractory metals ; but the most intense heat, at any considerable dis- tance, is produced by several concave mirrors, which reflect the rays to one focus. Metals and minerals have thus been melted at the distance of 40 feet, and wood ignited at the distance of 120 feet from the mirrors. 2. Chemical Action. Caloric is often produced by chem- ical and electrical action. A very great heat occurs in the phenomena of combustion, which may be defined to be the disengagement of light and heat in substances by chemical action. But the most intense heat is produced by voltaic or electrical action. 3. Condensation. It has been already stated that sub- stances develop caloric by diminution of their bulk, as when gases pass to liquids and to solids. A fire is often kindled by rubbing pieces of dry wood against each other; heavy machinery, if not properly oiled, often ignites wood, and axletrees of carriages are burned off; the sides of vessels are set on fire by the descent of the cable. The friction in these cases condenses the parts, and the caloric is developed. So, Nature of Caloric. 65 when iron is struck with hammer several times, it becomes hot. Fire is also struck from steel with any hard substance, like flint. This is denominated percussion. 4. Vital Action. The caloric developed by vital action is supposed to be owing, in part, to the chemical action of the air upon the blood ; but it is more probable that the vital principle operates to produce most of it, in a way not well understood. Sources of Cold. The sources of cold are, liquefaction, vaporization, and rarefaction.* SECT. 4. NATURE OF CALORIC. On this subject there are two theories. Sir H. Davy and some others considered caloric as a property of matter ; and Sir William llerschel and Prof. Airy have attempted to ex- plain its nature by supposing that there exists a subtile ether, which pervades all space and all matter, and that caloric is the effect of vibrations made in this fluid, somewhat similar to the vibrations of the air which produce the sensation of sound. This theory is called the undulatory theory, and is most favorably received by chemists. Sir Isaac Newton supposed that caloric was a subtile, ma- terial fluid. If caloric is material, it is matter under very peculiar circumstances. So far as we can determine, it pos- sesses few, if any, of the common properties of matter; its particles are self-repellent, opposed to cohesive attraction. If it is material, its particles must be exceedingly small, as they penetrate all other substances, however dense. They must also be influenced by gravity ; but no quantity of them, however great, possess the least appreciable weight. It pos- sesses neither extension nor impenetrability ; but if it is mat- ter, it must have these properties. 6* 66 Physical Properties of Light Refraction. CHAPTER II. LIGHT. The physical properties of light belong to the science of Optics, a branch of Natural Philosophy. But light has also chemical properties, which come within the province of Chemistry. I. Physical Properties of Light. Light is emitted from every visible point of a luminous object, and is equally dis- tributed on all sides, if not interrupted, diverging like radii drawn from the centre to the circumference of a sphere. It travels at the rate of 192,000 miles in a second, requiring about eight . Nitrate of lead and hydriodic acid, yellow. Exp. Vegetable infusion and, an alkali, green. Exp. Aquae ammonia and sulphate of copper, blue. /,*>/;. Ferro-cyanuret of potasaa and sulphate of iron, indigo. E.cp. Red and indigo, mixed, form vk>let. 3. When all the rays are absorbed, so that none can be reflected, the body is black ; for the same reason, everything * See Jour. Franklin Inst. XXIV. 207. 70 Light. Ignition Phosphorescence. is black in total darkness. If none of the rays are absorbed, and all are reflected, the body is white.* VI. Ignition and Incandescence. The phenomena of ignition and incandescence include all kinds of artificial light, which is obtained by the combinations of inflammable matter, or the heating of non-combustible bodies. Solids begin to emit light in the dark at 700, and in the light at 1000 F. Gases require a higher temperature; flame is in- candescent gas. The color of the rays depends upon the kind of substances and the degree of heat: the white light of oil, candles, etc., when transmitted through a prism, has but three primary colors red, yellow and green. The dazzling light emitted by lime intensely heated, gives the prismatic colors almost as bright as the solar spectrum. Different substances assume different colors when intensely heated. Chemical rays exist very feebly in most artificial light, but in the intense light of lime, under the compound blowpipe, they are more easily detected. VII. Phosphorescence : There are many substances in nature which possess the property of shining in the dark, without the emission of caloric. These are said to be phos- phorescent, and are known by the term phosphori, (although there is no phosphorus connected with the phenomena.) 1. Solar Phosphori. Many bodies acquire this property on exposure to the solar rays for a few hours. Such, for example, is Canton's phos- phorus, a composition made by mixing three parts of calcined oyster shells with one of the flowers of sulphur, and exposing the mixture for an hour to a strong heat in a covered crucible. Chloride of r;-l- cium (Homberg's phosphorus) possesses the same property ; also, nitrate of lime, (Baldwin's phosphorus,) and a variety of other sub- stances, such as carbonate of baryta, strontia and lime, the diamond, fluor-spar or chlorophane, apatite, boracic acid, etc. Scarcely any phosphori act unless they have been exposed to light. When phosphorescence ceases, it can be restored by a second exposure to the light, or by passing electric dis- charges through the substance. 2. Phosphorescence from Moderate Heat. Chlorophane and several mineral substances require to be heated before * Colors have an important influence on the absorption and disen- gagement of odorous matters. White bodies are the least absorbent, and dark the most so. Photometers. 71 they phosphoresce. Lime is a remarkable instance ; when heated, it gives out a dazzling white light, too intense to look upon without injury to the eyes. Light is also emitted during the crystallization of many salts, as the sulphate of potassa and fluoride of sodium. Exp. Put three drachms of the vitreous arsenous acid into a matrass, with an ounce and a half of hydrochloric acid, and half an ounce of water; boil the mixture for ten minutes, and then suffer it to cool slowly. When crystallization commences, each little crystal will be attended by a spark ; on sudden agitation, great numbers of crystals shoot up, accompanied with an equal number of sparks ; if larger quantities are taken, and the vessel shaken at the right moment, the emission of light is so powerful as to illuminate a dark room. 3. Animal and Vegetable Phosphori. Some animal and vegetable substances emit light at common temperatures, without exposure to the sun's rays. This property is re- nrirkable in some fish, as the mackerel ; the light makes its appearance just before putrefaction commences, and ceases when it is completely established. Some species of decayed wood possess this property in a remarkable degree. VIII. Photometers. It is sometimes desirable to measure the intensity of light, emitted from different objects, and an instrument has been invented for this purpose, called the Photometer, or light measurer. The principal one employed for this purpose is that of Leslie. It consists of a very delicate and small differential ther- mometer, one bulb of which is made of black glass, and the whole is enclosed in a small glass tube. The white ball transmits all the light and heat, and is of course unaffected ; the black ball absorbs all the rays, and heats the air within, so as to cause the liquid to rise. Its action of course depends upon the heat produced by the absorption of light. Some objections to this instrument have been stated by Turner. Count Rumford's Photometer determines the comparative strength of lights, by a comparison of the shadows of bodies. Sources of Light. These are similar to those of caloric the sun, stars, chemical action, mechanical action, and caloric. IX. Nature of Light. Light and caloric have been re- garded by some as identical. Newton supposed that light 72 -- Electricity. was a material, subtile fluid, which emanated from luminous bodies in all directions in right lines, and produced the sen- sation of vision, by falling upon the retina of the eye; this is termed the Newtonian theory. But Descartes, Huygens, and Euler, proposed a different theory, which has been lately revived by Sir John Herschel and Prof. Airy. This theory supposes that light is produced by vibrations in an elastic medium, which pervades all space, and that vision is the effect of these vibrations, meeting the retina, in the same manner as pulsations of air impress the nerve of hearing, and produce the sensation of sound. At present, the strongest evidence is in favor of this theory, which has received the name of the undulatory theory. (See Sir J. Herschel's article on Light in the Encyclopedia Mi-tro/ml- itana.) Either of the above theories answers the purpose of classifying the facts, and it is not material which is adopted. CHAPTER III. ELECTRICITY. The word electricity is derived from the Greek name for amber,* a substance which possessed the property of at- tracting light bodies when rubbed. 1. If a piece of sealing-wax, or a glass rod, be rubbed with a dry woollen or silk cloth, each becomes capable of attracting and repelling light substances. In this state each is said to be electrified, or electrically excited. When friction is applied to many other substances, they exhibit similar phe- nomena. The cause of this attraction and repulsion is as- cribed to an agent called electricity, and when it is excited by friction, it is designated by the title of common elec- tricity. 2. If a plate of copper and a plate of zinc, having copper wires soldered to each, be immersed in acidulated water, and the ends of the wires brought into contact, they will * HlexTQov. Common Electricity. 73 exhibit similar phenomena of attraction and repulsion. When electricity is excited in this way, there is always a chemical action between the metal and the liquid, and it is called Galvanism, in honor of Galvani, who made the discovery; also Voltaic electricity, from Volta, who first demonstrated its existence as independent of the animal system. SECT. 1. COMMON ELECTRICITY. Common electricity is generally excited by the friction of one substance upon another. 1. If a piece of sealing wax, or any resinous substance, be rubbed with a silk cloth, and a pith ball, suspended by a thread, be brought near it, the ball will be at first attracted, and then repelled. 2. If a rod of glass, or other vitreous substance, be rubbed in a similar manner, and brought near the ball, it will attract it, while the seahng-wax will repel it. 3. If two balls be each electrified by the sealing-wax, or by the glass; they will repel each other ; but if one is electri- fied by the wax, and the other by the glass, they will attract each other ; hence, when friction is applied to resinous and vitreous bodies, opposite effects are produced. The state induced by friction upon the glass, was called by Dr. Frank- lin positive, and that induced upon the wax negative, and the substances were said to be positively or negatively electrified. Theories. 1. Franklin. supposed that electricity pervaded matter generally, and that friction tended to bring it upon the surface of bodies, or drive it from them ; that it was in its nature self-repellent, but possessed a powerful attraction for common matter; when a body was electrified positively, it had more than its share of electricity , when it was electri- fied negatively, it had less than its natural portion. 2. Du Fay supposed that there were two fluids : the one de- veloped by the friction of the glass he called vitreous, which . answers to the positive electricity of Franklin, and the other, developed by the friction of the wax, he called resinous, which corresponds with the negative electricity of Franklin. Each 7 74 Electricity. Gold Leaf Electrometer. fluid repels itself, and attracts the other. It follows from this theory, that substances electrified by the same fuid rv a brass chain, C. Attached to the machine is a cylindrical metallic conductor, P, which is also insulated by a glass pillar. When the machine is in operation, vitreous electricity flows from the rubber and glass, by means of fine points, to the prime conductor, P, and resinous electricity passes in an opposite direction. If the hand be placed upon the con- ductor, currents of electricity will pass in opposite directions, the vitreous passing into the body from P, and the resinous down the chain G to the ground. But if the hand be held at a little distance from the conductor, a spark will dart though the air, and cause a prickling sensation, accompanied by a slight report, with light and heat. The sound is pro- duced by the collapse of the air, as the fluid forces a passage through it; and the light and heat are supposed to result from the sudden condensation of the air, as in the fire syringe. Induction. If an insulated body be brought near the prime conductor, it will manifest signs of electricity opposite to that of the conductor, on the side nearest the conductor, and similar to the conductor on the other side, while the centre of the body will be neutral. The electricity, in this case, is induced by the presence of the electrified conductor; and 76 Electricity. Induction Theory. the process is called induction. Several insulated conductors placed contiguous, will exhibit the same phenomena if a communication be made between the last and the ground. Thus, (Fig. 31,) Fig. 31. let A represent the positive conductor of an electric ma- chine, b and c in- sulated conductors, with a chain pass- ing to the ground. The conductor b will be electrified by induction, as will he indicated by the attached balls. Thus 1, being positive, will attract 'the balls 2, which are rendered negative by induction. The balls 3 are also rendered positive, 4 negative, and "> positive, while the centres b c will remain neutral. Theory. The phenomena of induction led Faraday to propose a theory of attraction and repulsion. The reason why an excited body attracts another is, that it induces in it an opposite electrical state. He considers induction an essential function, both in \he development and continuance of electrical currents; that it consists in a polarized state of the particles, or positive and negative points, induced by the presence of an electrified body. Application of the Theory. According to this theory, an excited body attracts light substances, because it induces in them an opposite state of electricity. 1. On moving the hand towards the prime conductor, it is electrified negatively by induction ; when a spark is received, the equilibrium is restored. 2. When a cloud, positively or negatively electrified, passes over a tower, or a tree, it induces an opposite state in them, and a stroke of lightning follows in consequence of the attraction between the two accumulated fluids ; hence the utility of lightning-rods to form a communication between the clouds and the ground. 3. The action of the Leyden Jar is due to induction. It consists of a glass jar, lined on the inner and outer surfaces, save a few inches near the mouth, with tin foil. Through the stopper, made of dry wood or sealing-wax, a brass rod com- Electrometers. 77 Fig. 32. municates with the inner surface. When positive electricity is applied to the inside, it drives off the same fluid on the outer surface, and induces the negative fluid. These fluids exert a strong mutual attraction upon each other, through the glass, and enable both to accumulate in larger quantities than they would do on separate conductors. When a com- mimic-ition is made between the inner and outer surfaces, the equilibrium is suddenly restored, accompanied by a sharp report. When several jars are connected by their outer surfaces, and also by their inner surfaces, they consti- tute an electrical battery. 4. The action of the Ekctrophorus (bearer of electricity) (Fig. 32) de- pends upon the same principle. It may be constructed by pouring melted resin into the cover of a firkin, taking care, \viicn it cools, to render the surface even. Ad ipt to this a circular piece of board covered with tin foil, and fix a glass rod in 1 lie centre for a handle. This instru- ment may be used instead of the machine for charging Ley- d'2n Jars. Electrometers, or Electroscopes, These are instruments for detecting the presence of electricity, as in the Gold Leaf Electrometer, (page 74,) or for determining the degree of its tension, or attracting and repelling power. For this last purpose, the Balance Electrometer is used. Thus A (Fig. 33) is a Leyden jar, which may be con- 7* 78' Laws of the Accumulation of the Electric Fluid. nected with the prime conductor of an electric machine ; B, a brass ball connected with D,* E ; C, another ball, with a chain, G, connecting it with the table or the outside of the jar ; D, a brass rod balanced at the centre, and insulated by the glass post H ; E is a ring which may be placed at any distance from F, bringing the ball in contact with B. If, now, the jur be positively electrified, the ball on the end of E will be re- pelled, C will be electrified negatively by induction^ and there will be a powerful attraction between C and the ball on the end of D, which will bring them together, and the equilibrium will be restored. The force of attraction will be measured by the distance between the balls and the weight applied at E. With a powerful electrical battery, successive vibrations may be produced in the beam, and a bright spark and loud report produced at each contact of the balls. Laws of the Accumulation of the Electric Fliti-.!. 1. Free electricity is always accumulated upon the surface of an insulated conductor, and does not penetrate its Mib- stance ; hence the quantity does not depend upon the t/iftinflti/ of matter in the conductor, but upon the extent of surface. 2. The mode in which electricity is distributed over the surface of conductors, depends upon their form. On a sphere, it forms a uniform stratum.- On an ellipsoid, the stratum is thickest on the extremities of the longer axis, and, as these extremities approach to the form of points, the accumulation increases till the tension becomes so great, that it flows off into the atmosphere; hence electricity cannot be retained on a conductor which has points attached to it. 3. This tendency to escape is due to the repulsion of its particles. 4. Coulomb proved by his Torsion Electrometer, that the repulsion of two bodies similarly electrified, and the attraction of two oppositely electrified, varies inversely, as the square of the distance between them. SECT. 2. VOLTAIC ELECTRICITY, OR GALVANISM. History. In the year 1791, Galvani, an Italian Professor of Anatomy at Bologna, discovered that if a silver probe were made to touch the crural nerve of a recently killed frog, and a strip of zinc the muscle, violent contractions would be pro- duced at each contact of the two metals the same effect as Simple Voltaic Circles. 79 is produced by an electric spark. Hence he concluded that the phenomena were due to electricity, generated by the animal system. Some years after, Prof. Volta, of Pavia, dis- covered that the animal system was not necessary to the de- velopment of this kind of electricity, which he proved by the construction of a pile of insulated plates, of different metals, called the Voltaic pile. This discovery has given to this form of exciting electricity the epithet voltaic. But the identity of the agent concerned in galvanism, and of that in the common, electrical machine, is now a matter of demonstration. Magnetism is doubtless due to the same agent, and probably chemical affinity, which reduces the four subjects to one, and renders it much more simple, and easy to classify effects which were once supposed to originate from as many distinct agents. I. Simple Voltaic Circles. Erp. Place a piece of zinc upon the tongue, and a piece of silver under it : whenever the projecting edges of these metals are brought into contact, a peculiar sensation will be perceived, and, if the plates are large enough, a flash of light. This effect is not due to elec- tricity generated by the animal system, but to that developed in the metals; for if the sa-ne plates, Fie. 34. or larger plates, be placed in water, (Fig. 34,) and the connection made, electricity will be excited; feeble in- deed, but in sufficient quantities to be detected by a proper apparatus. If, however, a few drops of sulphuric or nitric acid be added to the water, and the ends of the plates C and Z brought into contact directly, or by means of wires soldered to the plates, bubbles of hydrogen gas will rise from the surface of the copper plate C, and electricity will be developed in larger quantities. The currents will continue to circulate from one plate to the other, as long as the ^ires are kept in contact, but will cease when they are separated. This is a case of a simple voltaic circle. The direction of the positive current is indicated by the position of the arrows. When the wires are in contact, the circuit is said to be closed, and a current of positive electricity flows through the water from the zinc plate Z to the copper C, and from the copper along the con- 80 Electricity. Compound Voltaic Circles. ducting wires to the zinc. A current of negative electricity, on the theory of two fluids, passes in an opposite direction. When the wires are separated, the circuit is said to be broken. The contact may be made above the water, or in it, or the plates may touch each other throughout, or be soldered to- gether; in either case electricity will be excited; but if one plate is out of the liquid, no currents can be produced. A simple voltaic circle may be formed of one metal and two liquids, provided a stronger chemical action is induced on one side of the plate, than on the other. Simple voltaic cir- cles may also be formed of vari< .s materials ; but, generally, they consist of one perfect and two imperfect conductors of electricity, or of two perfect and one imperfect conductors. Metals and prepared charcoal are perfect, water and aqueous solutions imperfect conductors. But, whatever be the construction, chemical action seems absolutely necessary to the development of voltaic currents. The most common and convenient form of the simple battery, is that of two cyl- inders of copper, C, (Fig. 35,) the one within the other, separated about one inch, with a bottom soldered on, so as to contain the exciting liquid, a, between them, and a cylinder of zinc, Z, placed between the two cylinders of copper, and insulated by ivory handles. The two plates are furnished with wires, terminated by the cups b 6, which contain a globule of mercury. The connection is made by means of wires dipped into the mercury in the cups. Or, the copper and zinc may be coiled around each other, so that each surface of zinc may be opposed to one of copper, but separated from it by a small interval. By thus exposing a large surface of zinc to a similar sur- face of copper, Dr. Hare was enabled to melt the most refractory metals, and from this circumstance gave it the name of Calorimotor. II. Compound Voltaic Circles. Compound circles consist of a series of simple circles, for the purpose of increasing the intensity of voltaic currents. The first combination of this kind was made by Volta, and is called the voltaic pile. Compound Voltaic Circles. 81 1. This pile consists of zinc and copper plates, Fig. 36. (Fig. 36,) placed alternately one above another, with strips of woollen cloth moistened with salt water between each pair. By connecting the top and bottom plates, currents of electricity will be set in motion. 2. But other forms of voltaic circles are now in use. The most convenient is that invented by Wollaston. It consists of any convenient number of zinc and copper plates, so arranged, that each zinc plate is surrounded by two of copper. A (Fig. 37) is a trough to contain the exciting liquid ; B a case passing around the plates, and -connected by chains to the windlass C, by means of which the plates can be lowered into the liquid, or raised to any position required.* EE are small hand-vices attached to the poles. The zinc plates are confined in copper cases, insulated by wood at each end. The copper cases are separated of an inch, by pasteboard, which, with the wood, is saturated by oil and wax. The connection between the zinc and copper plates is made by strips of copper soldered to the zinc of one pair, and to the copper of the adjacent pair; by this construction, the power of the battery is increased nearly one half. Fig. 37. - As each zinc plate is connected to the adjacent copper plate, the currents nre urged along from one to the other, in opposite directions, till they meet at the poles. The size and number of plates may be varied at pleasure. The largest battery ever constructed is that of Mr. Children, * In some batteries, the plates are stationary, and the trough is raised and lowered. This is the most convenient construction, especially ia large batteries. 82 Electricity. Theories of Galvanism. the plates of which were 6 ft. long and 2 ft. 8 inches broad. The most convenient size is 4 inches by 6. A battery con- taining 200 or 300 plates, and thrown into vigorous action, is nearly as powerful as one much larger.* The battery of Dr. Hare is called a Deflagrator, from its surprising power of burning the metals. The direction of the currents in this apparatus is the same as in the simple circles : positive electricity passes from tfie zinc through the liquid to the copper plates, and is given off at the copper pole of the battery, while negative electricity takes the opposite direction, and appears at the zinc or negative pole. During the action of the battery, all the hydrogen evolved in the process is given off at the surface of the copper, and the weight of the hydrogen during any given time, and thnt of the zinc dissolved, will be as 1 to 32.8, which is the ratio of their chemical equivalents. This shows the close con- nection between electricity, thus excited, and chemical affinity. Theories of Galvanism. On this subject there are three theories: 1. The first originated with Volta, who conceived that electric currrnts are set in motion, and kept up, solely by contact of the dif- ferent metals. He regarded the interposed solution merely as a conductor to convey the electricity from one point to another. 2. The second theory was proposed by Dr. Wollaston, who supposed that chemical action was the sole cause of exciting and continuing the voltaic currents; and the fact that no sensible effects are produced by a combination of conductors, which do not act chemically upon each other, is the strongest proof of its truth : even in the' voltaic pile, the energy of the action depends upon the oxidation of the zinc. * In experimenting with the battery, the plates should not be im- mersed in the liquid but a few minutes at a time ; by raising 1 and low- ering them for each experiment, their vigorous action will be kept up much longer ; or the troughs may be so constructed, that, by a partial icvolution, the exciting liquid may be withdrawn from the plates, or thrown upon them at pleasure. Laws of the Action of Voltaic Circles. 83 3. The third theory was suggested by Sir H. Davy, and is intermediate between the two preceding. He supposed that the electric equilibrium was disturbed by contact of the metals, and the electric currents kept up by chemical action. The theory of Wollaston is now generally embraced. Laws of the Action of Voltaic Circles. Electricians distinguish between quantity and Intensity in Galvanism, as in ordinary electricity. Quantity refers to the amount of the electric fluid set in motion; tension, or intensity, to the energy or effort with which a current is iaipelled. Common electricity has great tension; voltaic, great quantity, and this is the principal difference between them. 1. In the broken circuit, there is a strain to establish ;in electric current, because without this, oxidation cannot take place. Tiiere exists between the exciting fluid and the zinc, a desire, as it were, for chemical action, which cannot be gratified until, by closing the circuit, a door is opened for the escape and circulation of electricity. This strain or tension is great, according as the affinity between the exciting fluid and the zinc is great. Currents of high tension are urged forward with greater impetuosity than feeble one's, and hence they more readily overcome obstacles to their passage. 2. Currents from a single pair of plates have not a hi^h A 7?s/Vw; but if the plates are large, a great quantity of elec- tricity is set in motion. The condition which causes a high tension is an extended liquid conductor, along the whole line of which successive pairs of plates are arranged ; each acted upon chemically by the exciting liquid, and urging on the current in the same direction. But the quantity in this case may not be great ; for, although its tension is increased by the force which each plate gives to the current as it passes, the quantity which passes along the wire, according to Faraday, is exactly equal to that which passes through one of the cells in which the plates are immersed. 3. The energy of voltaic currents is measured either by their power of deflecting a magnetic needle, or by that of chemical decomposition. The deflection of the needle depends 84 Electricity. Effects of Galvanism. upon quantity; hence a single pair of plates will deflect the needle more than a number of small ones combined ; but de- composition depends upon quantity and intensity together. The decomposing power of the battery, however, does not increase in the ratio of the number of plates, but as the square root of the number, so that, when the number varies as 1 to 4, the decomposing power is as 1 to 2. The deflecting power of a single pair of plates varies in- versely as the square root of the distance between them. Thus, if a plate of zinc be placed at one, four, and nine inches from a plate of copper, the deflecting powers will be in the ratio of 3, 2, 1. 4. The velocity of common electricity through perfect con- ductors, is surpassed only by that of light, being, according to Wheatstone's Experiments, about 118,000 miles per second. From some experiments, it is infered that the velocity of voltaic electricity is somewhat less. Hence this agent h;is been employed to communicate intelligence from one place to another. The Electro-Magnetic Telegraph, by which this is effected, depends upon the velocity of electricity and its power to deflect the magnetic needle. Effects of Galvanism. I. The effects of common and voltaic electricity have many points of resemblance. 1. If a zinc and copper plate be immersed in dilute nitric acid, and the wire attached to the zinc plate be made to touch a gold leaf electrometer, the leaves will diverge with negative electricity, and if the wire of the copper plate be applied, it will indicate positive electricity. This effect is much greater when a battery of several pairs of plates is employed. It appears to be due to the disturbed equilibrium in the zinc plate ; the chemical relation of which to the acid renders the metal positive, at the expense of the attached wire, while the copper plate, induced by the contiguous zinc, be- comes negative, at the expense of its wire, which becomes positive. 2. A Lcyden jar may be charged from either wire of an unbroken circuit, provided a large quantity of electricity be developed, connected with high tension. This effect depends upon the number of plates and the energy of the action. 3. Voltaic, like common electricity, passes through the Effects of Galvanism. 85 air, and other non-conductors, in the form of sparks, accom- panied with a report, and the development of light and heat. Hence it will inflame gunpowder, phosphorus, hydrogen and oxygen, and other inflammable substances. 4. Its tension, however, is so feeble, compared with com- mon electricity, that it has, according to Mr. Children, a very small striking distance; i. e., the space of air through which the spark will pass is comparatively small. With a battery of 1250 pairs of four-inch plates, he found the striking dis- tance to be ^\y of an inch. If the air be rarefied, the distance will be increased, and diminished by condensation. 5. The effect of voltaic electricity upon the animal sys- tem is similar to that of common electricity. 6. Both kinds also deflect the magnetic needle, and pro- duce chemical decomposition. II. One of the most surprising effects of voltaic currents is their power of igniting the metals. Exp. Attach to each pole of the battery strips of metallic leaves, and bring them in contact ; the metals will burn with the most vivid scintillations. (See Fig. 37.) The color of the light varies in different metals. Gold leaf burns with a white light, tinged with blue, and yields a dark brown oxide. Silver emits an emerald-green light, of great brilliancy ; copper, a bluish-white light, with red sparks; lead, a beautiful purple ; and zinc, a brilliant white HI; lit, tinged with blue and red. If the communication be made with charcoal points, (that from the box-wood is the best,) the light is equal, if not superior, in intensity, to that emitted during the combustion of phosphorus in oxygen gas, and the heat is sufficient, it is said, to partially fuse the car- bon, a substance which is fusible by no other means of pro- ducing heat.* Theory. The heating power seems to be due, for the most part, to the quantity of electricity developed ; hence, for melting wires, a calorimotor is preferable to a compound bat- tery. The heat is supposed to arise from the difficulty with which the electric currents pass along the conductors ; but * On examining the points after they have been subjected to the action of a powerful battery, one will present a conical appearance, like the head of a pin, the other a corresponding cavity. The matter thus transposed has been supposed to be partially melted ; but probably it is nothing but earthy matter in the carbon. 8 86 Electricity. Chemical Effects of Galvanism. as the substances are good conductors, the effect will take place only when the quantity of electricity transmitted, is out of proportion to the extent of surface over which it has to pass. As heat and light are produced in vacua, under water, or in gases which do not contain combustible matter, these phe- nomena cannot be attributed to combustion, but to the pro- duction of light and heat by the electric fluid itself. The effects of common electricity from the electric machine, and in the case of lightning, are so similar to those above described, that there can be no doubt of the identity of the agents concerned in their production. III. Chemical Effects of Galvanism. The phenomena which accompany chemical combinations are similar to those produced by voltaic electricity. But the agency .of voltaic currents to effect the decomposition of chemical compounds is a most important and useful discovery, which was first made by Carlisle and Nicholson. 1. The first substance decomposed by the gal- vanic battery was water. The water for decom- position is put into a small vessel, a, (Fig. 38.) The tubes h o, after being filled with water, are inverted in the vessel, passing through holes in the stopper; n and p are platinum wires passing through the sides of the vessel into the open ends of the tubes. When the poles of the battery are connected with the wires, the positive with p, and the negative with n, hydrogen gas is disengaged at the negative, and oxygen at the positive wire. The two gases will rise up in the tubes in small bubbles, and displace the water. By measuring the gases, it will be found that there will be exactly two measures of hydrogen in the tube h to one of oxygen in the tube o. If the gases are col- lected in the same tube and exploded in the eudiometer, they will entirely disappear, and water will again be formed. By this means, the composition of water, both by analysis and synthesis, is accurately ascertained. This important discovery led to similar trials upon other substances. Other compounds, such as acids, salts, and alka- Chemical Effects of Galvanism. 87 lies, were subjected to the agency of galvanism, and all were decomposed one of their elements appearing at the positive, the other at the negative pole. In these decompositions, it was found that the same kind of body always went to the same pole. The metals, inflammable substances in general, alkalies, earths, and the oxides of the common metals, were uniformly found at the negative wire, while oxygen, chlorine, and the acids, were found at the positive pole. This led to a division of substances into Electro-positive, and Electro- negative adistinction,however, which is not found, by later experiments, to accord with facts. 2. The transfer of chemical substances from one vessel to another was noticed by Sir II. Davy. This transfer may be shown by two wine-glasses, (Fig. 39.) Put a solution of sulphate of soda into one, 71, and distilled water into the other, p ; then connect them with moistened amianthus or cotton thread. If, now, the negative pole of the battery is connected with n, and the pos- itive with p, the acid will pass over into the cup p containing the distilled water if the poles are reversed, the alkali will pass over into this cup. If, instead of distilled water, infusion of purple cabbage be used, the presence of the acid will be detected by the red color which it will give to the infusion, and that of the alkali by its changing the infusion to green.* But the effect in this experiment, and in those where three vessels are used, (the middle one of which, although contain- ing a very delicate test of the presence of an acid or of an alkali, will suffer them to pass through it without detection,) can be accounted for on the principle that a part of the salt passes over into the cup by capillary attraction ; as it has Fig * A very simple apparatus for showing the changes of color when salts in solution are subjected to galvanic action, is shown in Fig. 40, which consists of a glass tube, bent in the form of the letter U. Fill both legs with a neutral salt colored with the infusion of purple cabbage ; on immersing the poles p and n } the color may be trans- ferred from one leg to the other as often as the poles are changed. 88 Electricity. Chemical Effects of Galvanism. been proved by Faraday that decomposition never takes place unless the electric fluid actually passes through the sub- stance. It was in pursuing these researches that Davy made his great discovery of the x decomposition of the alkalies and earths, which, until that time, had been considered simple bodies.' 77ieory. The theory of decomposition, proposed by Davy, was this : He conceived that the poles of the battery were centres of attraction to one element of the compound, and of repulsion to the other ; hence, when the two poles were im- mersed in water, the. oxygen of the water was attracted by the positive, and repelled by the negative pole, while the hy- drogen was repelled by the positive and attracted by the neg- ative pole. The elements, thus acted upon by four forces, were separated, and made to appear at their respective poles. But this theory does not account for all the phenomena. If it were true, we should expect decomposition to be effected by one pole alone, as it exerts the attractive and repellent influence ; but this is never the case. Mr. Faraday has lately revised this part of the subject, and not only, added much that is new, but shown that many prin- ciples, especially the above theory, are erroneous. He contends that the poles have no attractive or repulsive tendency, but simply afford a path for the voltaic currents to enter the liquid. Instead of poles, he calls them elec- trodes* which means the way or door for electric currents, and may be air, water, metal, or .any other substance ^capable of conducting the currents to and from the substance to be decomposed. The point where the positive current enters the liquid, he calls the anodej and that where it quits it, the cathode, f When a compound is decomposed by galvanism, it is said to be electrolyzed,$ and substances capable of decomposition are called electrolytes; the elements of an electrolyte are * From yJLixTQor and 6$o=;, a, icay. t From ai, upwards, and o(W, the way in which the sun rises. t From xctro, downwards, the way in which the sun sets. From jjAexrfov and xuw, to unloose or set free. Results qf Faraday's Investigations. 89 called ions* Anions are the ions which appear at the anode ; cations, those that appear at the cathode. The anions are the electro-negative substances, such as oxygen, chlorine, acids, etc. ; the cations, the electro-positive, such as hydro- gen, alkalies, metals, etc. The following are the principal results of Faraday's inves- tigations : 1. All compounds, contrary to what has been hitherto supposed, are not electrolytes ; that is, are not directly de- composable by the voltaic currents. But many bodies may be decomposed by secondary action. Thus water is directly decomposed by an electric^ current ; but nitric acid is decom- posed by secondary action the decomposition of the water contained in it, aids the decomposition of the acid. Very numerous secondary actions are produced in this way, because the disunited elements, separated by direct action, are pre- sented in their nascent form, which is peculiarly favorable to chemical action. 2. Most of the salts or secondary compounds are resolva- ble into acid and oxide ; but in the binary compounds, such as acids and oxides, the ratio of combination has an influence which has been hitherto overlooked. No two elements ap- pear capable of forming more than one electrolyte. The proto-chloride of tin is readily decomposed, but the by-chlo- ride is not. Hence substances which consist of a single equivalent of one element, and two or more of another, are not electrolytes, that is, are not decomposed directly by electricity. 3. Most of the simple substances are -ions, that is, capable of forming compounds decomposable by galvanism. 4. -A single ion, by itself, has no tendency to pass to either of the electrodes, that is, it is indifferent to the voltaic cur- rents. 5. There is no such thing as a transfer of the ions, in the sense supposed by Davy. In order that the elements of water should appear at the two electrodes, there must be a row of particles between them. 6. The air, or the surface of water, may constitute an elec- trode, as well as metals. 7. Electro-chemical decomposition cannot occur unless a current of electricity actually passes through the compound ; * From tov, going, neuter participle of the verb to go. 8* 90 Theory of Electro-Chemical Decomposition. that is, the compound must be a conductor of electricity. On this principle many substances, by change of state, resist decomposition. Water is easily decomposed, but ice is not; many solid substances, also, are not electrolytes, because they are not conductors. CHemical compounds differ in the trical force required for their decomposition ; some require but a feeble current, others a powerful one. 8. The conduction of the electric currents in the cells of a battery depends upon decomposition. If the zinc or the cop- per be attacked chemically by a substance which is simple, or a non-conductor, no currents can be set in motion. 9. Electro-chemical decomposition is perfectly di finite ; that is, in the voltaic circle 32.3 parts of zinc are dissolved during the evolution of one part of hydrogen. This is in the ratio of their chemical equivalents. The same is true of all electrolytes. Hence Mr. Faraday has given to the quantities of electricity, requisite to effect the decomposition of various substances, the name of electro-chemical equivalents. This is a new and important discovery ; it seems to prove that the cause of chemical combination or affinity is eltitridtti. Hence, in order to estimate the quantity of electricity circu- lating in a voltaic apparatus, it is only necessary to collect the gas evolved from the acidulated water during any given time. Theory of Electro-Chemical Decomposition. We have al- ready noticed the theory of Davy, which supposes that all substances are in one of .two states of electricity, and that the poles have an attractive and repulsive force ; but Mr. Faraday has shown that this theory cannot be true. All substnnr* < are indifferent when by themselves, but assume one of the two states when brought in contact. Only one substance is absolutely negative oxygen ; and but one absolutely posi- tive potassium : between these extremes, they may be made to assume either positive or negative states. To account for the decomposition of water, we must conceive of a line of particles between the two electrodes, along which the current passes. When a particle of oxygen is evolved at the positive electrode, its hydrogen is not transferred at once to the op- posite electrode, but unites with the oxygen of the contiguous particle of water, on the side towards which the positive current is moving ; then it passes to the next, and so on, until Magnetic Effects of Electricity. 91 it arrives at the pole. A similar row of particles of oxygen start from the negative electrode at the same moment, and combine successively with, the particles of hydrogen as they pass them on their way to the positive pole or electrode.* Jjt is supposed that other compounds are decomposed by a similar process. Magnetic Effects of Electricity, of Electro-Magnetism. History. It had been noticed for a long time that, when a ship, for example, was struck with lightning, the magnetic needle often had its poles destroyed or reversed, and that the iron often became magnetic. This led to the supposition, that electricity might be employed to communicate the mag- netic properties to iron or steel ; but no results of importance were obtained until the winter of 1819, when Prof. Oersted, of Copenhagen, made his famous discovery, which forms the basis of a new and very important branch of science. I. Influence of Voltaic Currents upon the Magnetic Nee- dle. The discovery made by Oersted was, that the me- tallic wire, or any part of a closed voltaic circle, causes a magnetic needle, when brought near it, to deviate from its natural position, and assume positions depending upon the relative position of the needle and the wire. Thus, suppose a magnetic needle freely suspended with its poles pointing north and south. (See fig. 41.) 1. If, now, a positive current pass from north to south in the same plane with the needle, but a little above it, the north pole will turn to the east, and the south pole to the west. 2. If the current pass under the needle, the north pole moves west, and the south east. 3. If the current pass on the west side of the needle, and in the same horizontal plane, the magnet will have a tendency to move in a vertical direction, the north pole being elevated, and the south depressed. 4. If the current pass on the east side, the north pole is depressed, and the south elevated. 5. If the current flow from south to north, the needle will move in opposite directions. * The quantity of electricity sufficient to decompose a single grain of water would be equal to a powerful flash of lightning. 92 Magnetic Effects of Electricity, or The deflection is rarely 45, in consequence of the mag- netism of the earth ; but if that force, is counteracted, as it may be, by suspending two magnets near each other, of equal power, with their poles reversed, the declination will be 90 ; hence the tendency of a magnetic needle is to stand at right angles to an electric current* 6. If the wire be placed in a plane, perpendicular to the one in which the magnet moves, and the positive current ascends or descends to the centre of the needle, no action will take place ; but if it be moved towards the north or south poles, they will be attracted or repelled, lltncr the plane in which a needle moves is always perpendicular to that in which the voltaic currents circulate. 7. The phenomena of Electro-Dynamic action result wholly from electricity in motion, and depend upon quan- tity alone ; hence a simple circle of large plates is best fitted for exhibiting it.* From the above facts it will be seen, that the magnetic needle may be employed, not only to ascertain the existence and direction of voltaic currents, but also to measure their force. The instruments used for these purposes are called Galvanometers or Atu&ipKo't. As it is proved by experi- ment that every part of a wire in a closed circuit exerts an equal force upon the poles of a needle, if we can increase the number of points, the combined force will be greatly increased. This can be done by coiling the wire into the form of a circle or rectangle; each coil will exert its own force, independent of its neighbor, and the united force will depend upon the num- ber of coils. Thus (Fig. ' *T 41) NP are the two ends ^ L of a copper wire bent in ^T V -^ ^ CL the form of a rectangle, 11 fn the centre of which, ^ u' IT and in a plane perpendio " * ular to the plane of the wire, is placed a mag- netic needle. A gradu- ated circular plate meas- * The simple battery, Fig. 35, p. 80, is best fitted for experiments on this subject. The exciting liquid should be a solution of sulphate of copper. "wr I CL Electro-Magnetism. 93 ures the degree of declination, which indicates the quantity of electricity circulating along the wires. It will be seen, that if the positive current pass above the needle from north to south, that is, from P to , and then pass around the south pole from A to B, there will be double the effect produced. By increasing the number of coils, the deflection of the needle will be much greater. This constitutes the Electro- Magnetic Multiplier of Schweigger. If the directive power of the needle be destroyed, or if the currents are sufficiently powerful, the needle will stand at right angles to the direction of the currents. Then, if, at the moment it has attained this point, the currents be sent in an opposite direction, it will perform a revolution. Thus, by changing the direction of the currents, a needle may be made to revolve rapidly. If the magnet is fixed, and the rectangle suspended free to move, it will exhibit the same phenomena while the voltaic currents are passing around it. '' Fig. 42. 94 Magnetic Effects of Electricity, or The Revolving Rectangle is constructed on this principle. MM (Fig. 42) is a permanent horse-shoe magnet ; C, a rec- tangular coil of copper wire, connected at each end to an axis, by which means it may be made to revolve ; ZP are two cups, to form a connection with the poles of a battery ; the wires bb are connected with the cups, and press on opposite sides of the cylindrical metallic pole-changer, which revolves between them. The pole-changer consists of two pieces of silver, with a small space between them ; one of these pieces is connected with one end of the wire of the rectangle, and the other piece with the other end ; a is an arch of brass to support the rectangle and the wires. If the two cups be connected with the battery, P with the positive, and '/* with the negative pole, the positive current will pass along the wire b next to N, and from the wire to one side of the pole- changer, and thence several times around the rectangle to the wire b next to S. When the positive current is passing from P around this rectangle, one side is impelled towards one pole of the magnet, and the other towards the other pole. When the sides arrive in the plane of the poles, the force still continues to act, and they are forced by, and complete half a revolution, standing again at right angles to the poles of the magnet, the point at which they commenced their revolution: at this point the pole-changer sends the currents in opposite directions, and the revolution is continued. Reverse the current, by chang- ing the battery wires, and the rectangle will revolve in an opposite direction. II. TJic influence of voltaic currents on soft iron and steel was noticed by Davy and Arago about the same time. If an iron or steel needle be suspended in the galvanometer instead of the common needle, at right angles to the conducting wires, permanent \magnetism will be communicated to the steel, and the iron will become powerfully magnetic, as long as the currents circulate, but will lose this property when the circuit is broken. Davy succeeded in- producing a similar effect by a discharge from a common electric battery. 1. This effect can be exhibited in the most satisfactory manner by coiling an insulated copper wire in the form of a helix, d, (Fig. 43,) and connecting the two ends of the wire bb with the cups CZ, into which the poles of a battery may Electro-Magnetism. 95 be inserted. Bars of soft iron or steel, placed in the coil, will become magnetized the instant the voltaic cur- rents circulate around the coil. If the positive current flows from Z around the helix, n will be the north pole, and s the south pole. If it flow from C, the poles will be reversed. 2. If a bar of soft iron (Fig. 44) be wound with copper wire from c to a in one direction, and from a to c? in an opposite direction, and currents of electricity passed around the bar, by connecting the wires b e with a voltaic battery, the bar will have three poles ; c and d will be similar poles, and a an opposite pole com- mon to the other two, as may be shown by bringing a magnetic needle near each. By changing the direction of the battery currents, the poles are reversed; hence the kind of pole depends upon the direction of the voltaic currents. 3. Although soft iron does not re- tain its magnetism, yet its magnetic properties, while the voltaic currents are passing around it, are truly sur- prising. If a soft iron cylinder, two inches in diameter, and bent in the form of a horse-shoe magnet D, (Fig. 45,) be wound with copper wire, and the ends BC connected with the battery, it will be converted into a powerful magnet. On applying the armature A, it will sustain several hundred pounds. Mag- nets of this description may be made to sustain from 200 to 2000 Ibs. It will be seen that the principle is the same as in the helix ; and, as in the mul- . 43. Fig. 44, Fig. 45. 96 Magic Circle. tiplier, by increasing the number of coils, the magnet becomes more powerful, but the force does not increase directly as the number of coils; for each additional coil is farther from the axis of the iron bar, and the power it exerts is inversely as the square of the distance from the axis. 4. The Magic Circle, with two iron ar- matures, acts also on the same principle. r (Fig. 46) is a coil of insulated copper wire ; ab the two ends which may be con- nected with the battery. When the wires b a are connected with the battery, and the two armatures are brought into contact, one of them passing through the ring, they adhere to each other very strongly, and, although they weigh less than J lb., they will sustain a weight of 56 Ibs. without separation. The voltaic currents not only communi- cate magnetism to the iron and steel placed in the ring, but the helix itself becomes magnetic while transmitting the cur- rents, as is proved by its attracting iron filings. These ,mv induction, the positive currents passing from west to east, because then they would coincide with the same currents in the earth which pass from east to west; hence the reason that a magnetic needle stands north and south, is, that the currents of electricity circulating around the earth, and those circulating in the needle, will coincide only when the needle takes that direction. VI. Thcrmo-Electricity. Thermo-electric phenomena re- sult from currents of electricity excited in metals by heat. The existence of these currents was first demonstrated in 1821 by Seebeck. If a magnet be suspended in a rectangle formed of a bar of antimony or bismuth, having its extremities connected with copper wires, -and heat applied to one end of the bar, the needle will be deflected in one direction, and in an opposite direction when heat is applied to the other end. Similar effects are produced when either end is cooled below the natural temperature. Other metals, treated in the same manner, exhibit similar phenomena, but bismuth and ai- timony are the best. Prof. Gumming has shown that a rotary motion may be produced by placing platinum and silver wires, soldered together in a circular form, upon a magnet, and applying heat. VII. Nature of Electricity. Some suppose that there is no transfer of any thing in what are called electric currents, but a process of induction passing progressively along among the molecules of a conductor. Others ascribe them to waves of vibrating matter, just as the phenomena of light and caloric are explained, by the undulatory theory. VIII. Uses of Electricity. 1. Both voltaic and common electricity have been employed in medicine ; in some cases, with highly beneficial effects. It acts powerfully upon the Electro-Magnetic Telegraph. 103 nervous system, and has been the means of restoring sen- sation to parts of the body which had become paralytic ; so powerfully does it act upon the vital energies, that persons who have been deprived of life, either by some accident, or by design, have been resuscitated by its agency. Its influ- ence is constant and universal in the animal, vegetable, and mineral kingdoms. 2. Attempts have been made to employ voltaic electricity as a motive power in the arts, to supersede the use of steam ; but all attempts hitherto have been unsuccessful. Suf- ficient power has been generated to turn a small lathe ; and it is to be hoped that an apparatus will yet be constructed to render available the great force which this agent is capable of exerting. This force depends upon the property of the voltaic currents to communicate magnetism to soft iron, thus producing a powerful attraction, arid the property of the iron to change its poles, and consequently its attracting and repel liner power as currents circulate in different directions. (See Fig. 42.) 3. Electro-Magnetic Telegraph. A most beautiful and useful application of voltaic electricity, to communicate in- telligence from one place to another, has lately been made, in the Electro-Magnetic Telegraph. Two stations are taken fit some distance apart; at one of the stations is the battery, with wires extending to the other station, and connected with a magnetic needle in such a way that, when the wires are attached to the battery, a motion is produced in the needle, to which is attached a pencil, to mark certain characters which are agreed upon as symbols of ideas. The wires at the second station may be connected with an electro-magnet, upon the poles of which an armature, having a letter or word, may be attracted the moment the currents circu- late. In this case, there must be as many electro-magnets as there are letters employed. The experimenter at the first sta- tion inserts the wires a, for example, in the battery, and the observer at the second station sees the armature move upon the poles of the electro-magnet, raising the letter a ; the wires con- nected with the letter b (or any other letter) are then inserted, and b rises. In this way any word may be spelled. A pencil may be attached to the armatures, to mark in a line all the a's, and in another line all the 6's, and so of all the other letters ; hence the words may be written down so as to be easily read. Intelligence may thus be communicated to any distance that is desired with the rapidity of lightning. 104 Electricity. Elcctrography : 4. Electrography. A still more recent application of voltaic electricity has been made to the " production of perfect metallic casts or copies of medals, copperplates, and other works of art." The discovery appears to have been made about the same time, by Prof. Jacobi, of St. Petersburg, and Mr. Spencer, of Liverpool. The instrument by which this effect is produced is the Electrotype ; and the effect depends upon the decomposition of some metallic salt, by which the metal is precipitated upon the object to be copied, either forming a mould for the cast, or raising lines which may be used for making impressions on paper or other materials.* Fig. 52 represents one form of the electrotype, and the mode of taking impressions. A is a glass vessel, in which a division is made by casting across it plaster of Paris, (earthen ware, a bladder, or any porous mem- . brane, as thick pasteboard, will answer the same purpose.) Into one of the partitions is put a saturated solution of sulphate of copper, and into the other acidulated water. The object C to be copied is soldered to one end of a wire, r/, and a piece of zinc, Z, to the other end ; the object is then iinmci >* -d in the cupreous solution, and the zinc into the acidulated water. The deposit of metallic copper then commences upon the object c, copying, with the most scrupulous exact- ness, every line, and even the shades of polish. In about two or three days, a complete mould may be obtained. The copper mould is separated from the matrix by gentle heat. Theory. The metallic salt and the water are both decomposed. The sulphate of copper is resolved into sulphuric acid and oxide of copper, the water into oxygen and hydrogen. The acid and oxygen go to the zinc, and the hydrogen and the oxide of copper to the copper pole, the hydrogen unites with the oxygen of the oxide of copper, and the me- tallic copper is deposited upon the metal or object to be copied. * For a description of this process, see Journal of Science, Vol. No. 1 ; also, Part IV. of Griffin's Scientific Miscellany. PART II. CHEMICAL AFFINITY I\ all those phenomena, which appropriately come under the observation of the chemist, chemical affinity is the great cause to which they are referred. Other agents, as light, heat, electricity, cohesion, etc., modify its action, and some knowledge of them is therefore an essential preparation for the study of this, the great subject of chemistry. The de- tails, to which we shall attend in the examination of particu- lar substances, are, almost exclusively, but the effects of this principle. The student, therefore, should be familiar with the circumstances which modify its action, its varieties or different modes of operation, its effects, and especially the laws in accordance with which these effects are produced. Chemical Affinity is an attraction, which acts only at in- .< ntiblc distances, between particles of different kinds* Co- hesion is distinguished from it, by acting only between par- ticles of the same kind, as well as by being governed by dif- ferent laws. Varieties of Chemical Affinity. Although this power is the same in all cases, it will facili- tate the progress of the student to distinguish some of the * A late writer (Griffin, Chemical Recreations) maintains that there is no such thing as chemical affinity, because we know merely that bodies combine. We might as^well deny that any force or power ex- ists because we see only its effects. From the fact that bodies do corn- bine, we infer that some power causes them to combine, although, indeed, we know nothing of it, except in its effects. X 106 Varieties of Chemical Affinity. different cases in which it operates. Between many sub- stances it does not exist at all, as is seen in mixing oil and water. The most simple case is the direct union of two sub- stances, as when oxygen gas and iron unite, and form iron rust. This is called Simple Affinity. The combination of alcohol with camphor is another example. Exp. But if water be added to this solution of camphor, the alcohol will combine with the water, and desert the camphor, which again ap- pears free, or is technically said to be precipitated. As the alcohol appears to choose the water in preference to camphor, such cases are called examples of single elective ujfinity* The following are examples of the same kind : Exp. Into a solution of sulphate of copper (blue vitriol) immerse a dean iron wire; the sulphuric acid (oil of vitriol) will elect the iron, and the copper will be precipitated, forming a metallic coating upon the wire. Exp. Into a solution of protonitrate of mercury put a sheet of cop- per, or cents, well cleaned with dilute sulphuric acid ; the nitric acid will elect the copper, and the metallic mercury will be. precipitated, and form a covering over the cents, which will give them the appear- ance of silver. But, in other cases, two compounds mutually decompose each other, and form two new compounds. EXT). Thus, if carbonate of ammonia and hydrochlorate of lime be mingled, each will be decomposed. The former consisting of carbonic acid and ammonia, and the latter of hydrochloric acid and lime, tfie carbonic acid will unite with the lime, and the hydrochloric acid with the ammonia, forming carbonate of lime, and hydrochlorate of ammo- nia. This change may be very easily understood from the annexed formula, in which the symbols are used.t C + Am. ' C abandons Am. and goes to Ca; at the same time HC1 abandons Ca, and goes to Am. ; and the results are C + Ca. and HC1 -f- Am. HC1 + Ca. * Elective djfinity is the basis of chemical science ; for if each sub- stance attracted every other with the same force ; when combination had once been effected, the decomposition of many, if not of most substances, would be impossible; h^hce there would be but few changes in matter which would come under the investigation of the chemist. t C= Carbonic acid, and Am. = Ammonia; HC1 = Hydrochloric acid, and Ca. = Lime. Operation of Chemical Affinity. 107 Exp. To a solution of alum (sulphate of alumina and potassa) add a solution of acetate of lead. Sulphate of lead and acetate of alumina are formed by a double decomposition. The sulphate of lead will be precipitated, and the acetate of alumina will remain in solution. Exp. Nitrate of ammonia and sulphate of soda will mutually decom- pose each other. In all cases of double decomposition, the alkali in one of the compounds will just neutralize the acid in the other, so that, if any delicate test of an acid or an alkali (as vegetable infusion) be placed in the mixture, no effect will be produced upon it ; hence, as the quantities of acid and of alkali, in all neutral salts, are just suffi- cient to saturate each other when double decomposition takes place, these quantities are called equivalents. Such cases are examples of double elective affinity* Cases are more numerous, however, in which the changes are much more complicated ; but they may all be referred to the three modes stated above. Circumstances which modify the Operation of Chemical Affinity. That one substance has a stronger affinity for some than for others, cannot be doubted. But combination and decom- position do not always depend upon the relative force of af- finity alone. Several circumstances modify the operation of this power. These are, cohesion, elasticity, quantity of matter, gravity, and the imponderable agents. I. Cohesion. In order that substances should combine with each other, it is necessary that their particles should be in contact. But cohesion holds together the particles of each substance, so that they cannot be freely intermingled. Co- hesion must, therefore, be destroyed to facilitate chemical action. This may be effected in three ways : 1 . By reducing the substance to powder. Exp. Take two pieces of crystallized nitrate of copper ; roll one of them up in tin foil ; grind the other to powder, and wrap it in a piece of the same metal; drop a little water upon both as they are rolled up. In a few minutes, that which is pulverized will combine with the metal, and burst into a flame, while the other will not be affected. Exp. Take two equal portions of chalk, and pulverize one ; pour * Single and double elective affinity are the same in principle. The only difference is, that, in the one case, a compound is decomposed by a third substance, and but two affinities are in operation, while, in the other, two compounds mutually decompose each other, arid four affin- ities are brought into action. 108 Operation of Chemical Affinity. dilute sulphuric acid on each, and the action will be rapid in the case of the pulverized chalk, but moderate in the other case. In this ex- periment, one of the substances is in solution ; and usually it will be found insufficient to pulverize botli substances, and resort must be had to the second method. 2. By dissolving the body in some liquid. Exp. Mix together tartaric acid and carbonate of soda; no action will follow; pour on water, and they will be dissolved, and a violent action ensue. Solution is effected when a solid is put into a liquid, and entirely disappears, leaving the liquor clear. The body which thus disappears is said to be soluble ; the liquid is called a solvent, and the compound liquor a solution. Water is the principal solvent; alcohol, ether, oils, alkalies, and acids, are also employed. When water, or any solvent, has dissolved as much of any substance as it can, it is said to be saturated, and the solution is called a saturated solution. Solution should not be confounded with diffusion, which is merely a mechanical mixture. Exp. This distinction may be seen by mixing magnesia in water. The particles of magnesia are suspended at first in the water, rendrr'mrr it turbid, and they would soon subside to the bottom ; but if nitric acid be added, the magnesia will be dissolved, and the water will become clear. Most substances are more soluble in hot than in cold water; as a hot saturated solution cools, the water will not therefore be able to hold in solution all of the sul>st;:m-<' which had been dissolved, and it appears again in a solid state. The power of cohesion has the ascendency over the affinity of the liquid for the solid, and forms the hitter into crystals. Hence the phenomena of crystallization are owini: to the ascendency of cohesion over affinity. By evaporation, also, the solid may be recovered from so- lution. In either case, the crystallization is often confused, especially when the process is rapid. Insolubility has been found'to exert a remarkable influence on affinity, in the case of an alkali with two acids, or an acid with two alkalies, one of which will form with the alkali a soluble, and the other an insoluble compound. The one which is insoluble is always formed in preference to the solu- ble compound. Exp. Thus, if nitric and sulphuric acids and baryta be thrown to- gether in water, sulphate of baryta, which is insoluble, will be formed in preference to nitrate of baryta, which is soluble. It is obvious that, while the solution of one of the substances Operation of Chemical Affinity. 109 is usually necessary, the solution of both will further facilitate the action. 3. By heat. Fusion is there duction of a solid to a liquid state by caloric, and facilitates chemical action by enabling the particles to intermingle, and come within the sphere of each other's affinity. In liquids a slight degree of cohesion remains, and hence heat is applied to them with advantage. A hot liquid will act more powerfully upon most solids than the same liquid when cold. II. Elasticity. Cohesion, as we have seen, opposes chemical action by keeping the particles out of the sphere of each other's influence. Elasticity, or the gaseous state, is still more unfavorable to the operation of affinity, because the particles are removed too far from each other to be at- tracted ; hence most gases, though possessing a strong attrac- tion for each other, will not combine unless they are in the nascent state, that is, when in the act of assuming the gase- ous form. In this way elasticity not only prevents chemical union, but it favors decomposition. 1. When two highly-elastic gases combine, forming a liquid or solid, the compound will be decomposed -by a very slight cause : the chloride of nitrogen is a familiar example. It is an oily liquid, composed of two gases. A slight eleva- tion of temperature will cause instant decomposition, even with explosive violence. Generally all compounds which contain a volatile principle are easily decomposed by a high temperature. Hence caloric sometimes favors chemical action by destroying cohesion, while at others it prevents it, and favors decomposition by promoting elasticity. 2. There are some gases, however, which readily combine at a high temperature, as in the case of gaseous explosive mixtures. Oxygen and hydrogen gases require the heat of flame to effect their union. The caloric, in such cases, ac- cording to Berthollet, expands the gases in immediate con- tact with the flame, which acts as a violent condensing force to contiguous portions, and brings them within the sphere of each other's attraction. The same explanation is applied to the combination of gases effected by passing electric shocks through them. III. Quantity of Matter. Oxygen combines with lead in 10 110 Operation of Chemical Affinity. three proportions, forming three distinct compounds. The peroxide, or that which has the greatest quantity of oxygen, is easily decomposed by heat; the second compound, in which there is less oxygen, requires a higher temperature to effect decomposition ; and the third, which has the least oxy- gen, will sustain the heat of our furnaces without yielding up its oxygen. Hence, generally, when one substance combines with another in several proportions, the affinity is stronger in the case of the less than of the greater portions* On this principle, also, when a salt is dissolved in water, the first portions are dissolved more rapidly than the last, and the force of affinity diminishes up to the point of saturation, when it is overcome by the cohesion of the solid. This principle led Berthollet to account for all chemical changes without the aid of affinity, the existence of which lie was disposed to deny ; but M. Dulong has found that the principle of Berthollet is not in accordance with the results of experiment. IV. Gravity. The influence of gravity on chemical action is seen when substances of different specific gravities com- bine; as, when two liquids are put together, the heavier liquid will sink to the bottom ; or, when salt is dissolved in water, the salt will remain at the bottom, and prevent the particles of water from coming into contact with those of the salt. V. Imponderable Agents. The influence of caloric over chemical phenomena has already been alluded to. It favors chemical action in the case of solids, by destroying cohesion, and opposes chemical action in the case of gases, by increas- ing their elasticity. The influence of light has already been noticed. Common electricity is often employed for the com- bination of gases, and galvanism for decompositions ; but the same effects may be produced by either. * In consequence of the influence of quantity of matter over chem- ical changes, the chemist generally employs more of one substance than is necessary to effect the decomposition of another. Measure and Effects of Chemical Affinity. Ill Measure of Affinity. Since some substances have a stronger affinity than others, attempts have been made to measure its different degrees of force. It was once supposed that its relative strength could be ascertained by the order of decomposition, as may be ex- plained from the following table: Sulphuric J3cid. Baryta, Lime, Strontia, Ammonia, Potassa, Magnesia. Soda, If to the sulphuric acid, united with the magnesia, forming the sulphate of magnesia, ammonia be added, the acid will leave the magnesia, and elect the ammonia, forming the sul- phate of ammonia. If to this, lime be added, the acid will desert the ammonia, and unite with the lime ; this again will be decomposed by the soda, and so on to baryta. Hence sulphuric acid has the strongest affinity for the baryta, and the force is in the order in which the several substances are arranged. / ' //. This order may be shown experimentally thus : To a filtered solu- tion of nitrate of silver add metallic mercury ; the silver will be precip- itated, and the nitric acid will combine with mercury, forming the nitrate of mercury. Immerse in this a piece of clean sheet lead; the mercury will now be precipitated, and the lead will remain in solution. Suspend in this a strip of clean copper; the lead will be thrown down, and the nitrate of copper will remain in s'olution. In this place a sheet of bright iron, and in a short time the iron will displace the copper, forming a solution of nitrate of iron. To this present a piece of zinc ; the iron will be separated, and the zinc will combine with the acid. Add liquid ammonia ; the zinc will be separated, and nitrate of ammo- nia remain in solution. To this pour lime water; the ammonia will be liberated in the form of a j^as. and nitrate of lime remain in solution. Add to this oxalic acid, and the oxalate of lime will be thrown down, while a mixture of water and nitric acid remains. Hence the practical chemist, when he wishes to decom- pose any compound, is enabled to decide upon the substance which will produce that effect. But the circumstances which modify the action of chemical affinity are so numerous, that the order of decomposition is not, in every case, the measure of affinity. To determine the 112 Effects of Chemical Affinity. relative force of affinity in doubtful cases, observe the ten- dency of several substances to unite with the same, under the same circumstances ; and then notice the apparent facility of decomposition, when these compounds are exposed to the same decomposing agent. / Effects of Affinity. The changes which accompany the action of affinity are changes of chemical properties of color, form, temperature, and specific gravity. I. Change of Chemical Properties. It is one of the most remarkable facts in chemistry, that, when two bodies combine chemically, the compound is generally possessed of properties entirely different from those of the components. Ezp. 1. Pour sulphuric acid upon magnesia, and the compound will be Epsom salts, entirely unlike either. Exp. 2. Burn oxygen and hydrogen gases, and water will be formed, which is wholly different from either of its constituents. There are some cases in which affinity produces com- pounds without much change of properties, as in the case of solution ; but the force of affinity in such cases is very feeble. Exp. Salt dissolved in water, and camphor in alcohol, are instances. II. Change of color is often the effect of affinity. Exp. 1. To the chloride of calcium add nitrate of silver, both in solution ; a white precipitate will be formed, which is the chloride of silver. (See page 69.) Exp. 2. To a solution of nitrate of lead add a few drops of hydriodic acid, and a beautiful yellow pigment will be formed. Exp. 3. Into an infusion of purple cabbage pour a few drops of any alkali, and the color will become green ; add an acid jrnis-i.-illy, drop by drop,* and the purple color will be restored; add a few drops more * For this and sim- Fig. 53. ilar purposes, the drop- ping tube a (Fig. 53) may be used, ft is a glass tube, with a bulb, as , with a small ap- erture at the smaller end, through which any liquid may be drawn up into the bulb by pla- cing the mouth upon the larger end. Having partially filled the bulb, Elace the thumb over this end, and, by admitting the air slowly, the quid will drop out at the smaller end. Effects of Chemical Affinity. 113 Fi?. 54. of acid, and it will become red. By the gradual addition of the alkali, the effects may now be reversed. III. Change of form frequently accompanies chemical combination. E.rp. 1. Take oxygen and hydrogen gases, and explode them; they will form a liquid water. Hence chemical affinity converts gases into liquids. I'.rp. 2. If the two gases, ammonia and the hydrochlo- ric acid, be brought together in their nascent state, i. e., at the moment of their for- mation, they will produce the solid hydrochlorate of ' ni'i'Miia. Hence chemical afrinity converts gases into solids. The two gases may be formed by putting hy- drochlorate of ammonia and lime in one retort, (Fig. 54,) and liquid hydrochloric acid in the other, and applying heat ; as the gases meet in the glass receiver b, they will combine and form a white solid. E.rji. -T Take chloride of calcium in solution, and pour in sulphuric acid ; a solid precipitate the sulphate of lime will be thrown down Hence affinity converts liquids into solids. Exp. 4. Into a solution of pearlash or saleratus pour sulphuric acid, and a portion of the liquid is converted into the form of a gas, which escapes with effervescence. l-lrjt. Add one part of fuming nitric acid to two of alcohol ; both liquids will be converted into ammonia, and pass off in gas. Hence affinity converts liquids into gases. ^ Eip. 5. Mix two solids, the nitrate of ammonia and sulphate of soda; on rubbing them in a mortar, they will become liquid. Hence chemical affinity converts solids into liquids. Erp. 6. Explode gunpowder; it will be wholly converted into gas. Hence chemical affinity converts solids into gases. IV. Change of Temperature. The heat arising from the combustion of fuel, is owing to chemical action. Exp. Wet a piece of paper with spirits of turpentine and sulphuric acid, and then throw on a few grains of chlorate of potassa; the paper will instantly be in flames. V. Change of Specific Gravity. In changes of gases into liquids or solids, or of the latter into the former, there is, of course, a great change of density. But where there is no change of form, there is usually more or less of this change. Exp. Mix 100 measures of strong sulphuric acid with 100 of water, and the mixture will be less than 200 measures. 10* 114 Laws of. Chemical Affinity. Laws of Chemical Affinity. The laws which regulate the action of affinity, constitute the most important part of the whole subject ; for they are the foundation of modern chemistry. As they are expressed mathematically, they have consequently imparted to it a high degree of accuracy, and greatly elevated its rank as a science. Most substances have been found to combine in dt finite f)ro- portions, and with such the laws of affinity are chiefly con- cerned ; but there are numerous cases of apparently indefinite proportions, which first demand a separate consideration. I. Indefinite Proportions. Of these there are two c: in the first of which, any quantity of one substance may be combined with any quantity of another. Thus a drop of alcohol will combine with a quart of water, or a drop of w.-itrr with a quart of alcohol. Exp. Take a large glass vessel, and fill it nearly full of water . r.,]i.r it purple with the infusion of red cabbage; a drop of sulphuric :icid will change it red, or a drop of alkali will give it a green color, which shows that both the acid and the alkali must combine with the whole of tin- water. In the second case, the proportions are indefinite within certain limits. Thus with 2J Ibs. of water, a pound or any less quantity of common salt will combine, but if a larger quantity of salt be employed, all the excess above a pound will remain undissolved. The limit to the process is the point o"t saturation. (See page 108.) The most common instances of indefinite proportions are solutions where the proportions are indefinite below the point of saturation. Instances of unlimited indefinite proportions are less numerous. It is important to observe, in these cases, that the force of affinity is usually feeble, and the change of properties slight. Thus, in the common liquors, the properties of the alcohol are slightly modified by its combination with water ; and in solutions there is also little change. II. Definite Proportions by Weight. In the most numerous and interesting cases of chemical combination, a certain portion of one substance unites with one, two, three, or Laws of Chemical Affinity. 115 more times a given weight of another. These cases are usually characterized by a greater energy of combination, and a much greater change of properties than thos^e which have been described. The great law of definite proportions by weight may be thus stated : 1. The proportions in which substances combine may be ef pressed by fixed numbers, or by the multiples of these num- bers. The following table is an illustration : Water is compo Binoxide of Hydrogen Protoxide of Nitrogen Binoxide Hyp'initrous acid Nitrous acid Nitric acid *' >sed of Hydrogen 1 part - " . 1 " - Nitrogen 14 " - " 14 " - " 14 " - " 14 " - " 14 " - - Oxygen 8 parts. 16 " " 8 " " .6 " L 24 " " 32 " u 40 " A comparison of all the cases shows that hydrogen enters into combination in less quantity relatively than any other substance. It is therefore taken for a standard of comparison, and in the above table appears as unity. The lowest ratio in which oxygen combines with other substances is eight times that of hydrogen. The lowest combining ratio of nitro- gen is fourteen. If any simple substance does not combine with hydrogen, its lowest combining ratio may be ascertained from its combination with any otter substance, whose ratio has been determined. Thus from the above table the com- bining ratio of nitrogen is seen in its compounds with oxy- gen, whose ratio was ascertained in its compounds with hydrogen. The lowest combining ratio is also called an equivalent, or proportional. (See page 107.) Inspection of the above table will show, that while eight is the lowest combining ratio of oxygen, it combines also in the ratio of 16, 24, 32, and 40 parts; that is, two, three, four, and five times the lowest r.itio, agreeable to the above-men- tioned law. There are some cases in which substances do not unite with one equivalent of one to one, two, or more equivalents of another, but apparently of one to one and a half. Such an irregularity conforms to the general law, on the supposi- 116 Laws of Chemical Affinity. tion that two of the former unite with three of the latter. In some cases, also, two equivalents of one substance unite with five of another. The law of definite proportions by weight may be thus illustrated algebraically : If x and y be the equivalents of any two substances, their compounds must be z+y, x-f-2y, x-|-3y, x + 4y, etc. ; sometimes we shall have 2x + 3y, and rarely 2 x-|-5 y. It is evident from the above that the equivalent of any compound is the sum of the equivalents of its constituents, each being multiplied by the number of times it enters into the combination. Thus, in the above table, the equivalent of water is l+8zr9, of nitric acid, 14-f-40=54, etc. 2. The second law of definite proportions is the follow- ing: Every substance has its constitution invariable. Thus nitric acid is always composed of one equivalent of nitrogen and five of oxygen. No other substances, and no other number of equivalents of these, by combination can form nitric acid. The same is true of every substance whose elements com- bine in definite proportions. The least change of these de- terminate quantities will either form an entirely different sub- stance, or a portion of that substance which is 'n excess will remain uncombined ; hence whatever be the circumstances under which chemical substances are formed, whether formed ages ago by the hand of nature, or quite recently by the agency of the chemist, their composition is always inva- riable. The merit of establishing this law is due to Wenzel, a Saxon chemist, who published his views in 1777. But Dr. Dalton, an eminent English chemist, discovered the first law, and deduced from the scattered facts a theory of chemical union, embracing the whole science, and first published in 1803. Drs. Wollaston, Thompson, and other chemists, fol- lowed out these views. But to no one, in this department', is science so much indebted as to Berzelius. Laics of Chemical Affinity. 117 The application of these laws, in the arts, is of immense importance. In the manufacture of compounds, they teach precisely what proportions of the ingredients should be used. If these are expensive, an excess of one would be a seri- ous loss. III. Definite Proportions by Volume. The principal law of definite proportions by volume is precisely similar to that of definite proportions by weight, the parts being determined by measure, as in the former case by weight. This law holds true only in the case of gases and vapors. It is supposed that substances which have not yet been made to assume the form of a gas or vapor, would conform to this law, if they should assume such form. The law may be illustrated by the following table : 100 vols. carbonic acid gas combine with 100 of ammoniacal gas. u u u 200 " " fluoboric " " 100 " " 200 " But there are two laws of definite proportions by volume, which do not hold true to the same extent in definite propor- tions by weight. The first is, that a simple ratio of one to two, one to three, &,c., exists between the volumes of differ- ent constituents in the same compound. This may be seen in the above table. The second law is, that, in combination, gases and vapors are condensed by a portion, which is in a simple ratio to the volume of one of the constituents. The laws of definite proportion by weight and by volume are not inconsistent with each other, for the specific gravity always bears such a relation to the combining ratio by volume as to establish their harmony. Thus hydrogen and oxygen combine in the ratio of two of the former to one of the latter by volume, and of one to eight by weight. But as oxygen is sixteen times heavier than hydrogen, one volume of it is eight times as heavy as two of the latter. In other words, the compound ratio of the specific gravity and of the equiva- lents by volume, is equal to the ratio of the equivalents by weight. 118 The Atomic Theory. Atomic Theory. Existence of Atoms. The atomic theory supposes matter to be composed of minute, indivisible atoms. Hypotheti- cally, matter is infinitely divisible, that is, to Almighty power; but in fact it is not infinitely divided. Sir Isaac Newton re- garded it as probable, "that the primitive particles, being solids, are incomparably harder than any porous bodies com- pounded of them, even so very hard as never to wear, or break in pieces; no ordinary power being able to divide what God himself made one in the first creation." Theory of definite. Proportions by Weight. When sub- stances combine in their lowest equivalents, they unite atom to atom, (Fig. 55 ;) Fig . 55 . in higher proportions, one atom of one to two, three, or more atoms of the other. This theory exactly accounts for the facts of definite propor- tions; for if in one compound we have one atom of A joined to one of B, and in another one of A joined to two of B, through the whole mass, the sum total of B in the latter case will be exactly twice as much as in the former case. Atomic Weight. If in a compound of one grain of hydro- gen with eight of oxygen there be an equal number of atoms of each, an atom of the latter will be eight times as heavy as an atom of the former. In this way we know the relative weights of the atoms of all substances, whose equivalents are known. As the numbers are the same, the terms are often interchanged. The absolute weight and magnitude of atoms cannot be determined. Dr. Thompson calculates that a cubic inch of lead contains more than 883,492,000,000 atoms. The shape of atoms is matter of hypothesis. They are generally supposed to be spheroidal. Isomerism. Cause of Chemical Affinity. 119 Isomerism. It was formerly supposed that when two elements combine in the same ratio, they must always give rise to the same compound ; but it has of late been discovered that this is not always the case. Thus there are 3 compounds of oxygen and phosphorus, whose composition is identical, each being composed of 31.4 parts by weight of phosphorus, and 40 parts by weight of oxygen ; and yet these substances differ in their properties. The same is true of the two cyanic acids. Berzelius has applied to such compounds, as a class, the general term isomcric, from two Greek words,* which ex- presses an equality in the ingredients; and to distinguish the isomeric bodies from each other the terms parai and mcta are prefixed. To reconcile the phenomena of isomerism with the theories of chemical combination, we have only to suppose that the same elements may combine in different ways, so as to give rise to compounds essentially distinct; for example, we may suppose that the 2 atoms of phosphorus and the 5 atoms of oxygen, which form 3 isomeric bodies, may be grouped dif- ferently; thus, 2 atoms of oxygen may first unite with the 2 of phosphorus, and this compound unite with the other 3 atoms of oxygen, or 4 of oxygen may unite with 1 of phosphorus, and 1 of oxygen with 1 of phosphorus : these two compounds may then combine, and form a different sub- stance from the first, although both contain the same number of atoms of each element. It is evident that these groups may be varied still further; hence the kind of substance may depend upon the order in which the atoms are united. In a few cases, the equivalents of isomeric bodies differ : defiant gas and etherine are an example. The equivalent of olefiant gas is 14.24, and that of etherine 28.48, or exactly double. Cause of Chemical Affinity. The cause of affinity is probably electricity. In those cases where the electrical state of substances can be ascer- tained, they are always found to be oppositely electrified, * loos, equal, and /te^oj, part. t Ilc/yct, near to. 120 Cause of Chemical Affinity. when combination takes place. Voltaic electricity is the most powerful decomposing agent, and the whole phenomena of electro-chemical decomposition seem to prove the identity of affinity and electricity. This view accords best with the simplicity every where observed in the laws of nature. By ascribing the phenomena of electricity, galvanism, mag- netism, and chemical affinity, to the same agent, we seem to be progressing in the chain of causation nearer to the great and ultimate cause, the agency of God. Some suppose that what we call the agents and laws of nature, have no real existence as distinct powers. They deny the agency of second causes, and ascribe every operation of nature to the immediate power of God. Others suppose that there are real agents or causes dependent upon God, but possessed of power in themselves, to act as second causes, or subordinate agents, in the various phenomena of matter. Whichever view we take, we must, in the end, refer the ultimate cause to the impulse of the divine will ; although, for the mere purposes of scientific classification, something, perhaps, is gained by the introduction of second causes. PART III. PONDERABLE BODIES Specific Gravity means the relative weight of different substances, compared with some standard. In the case of solids and liquids, the weight of the body is compared with water as unity ; i. e., if a given quantity of water by measure be weighed,* and that weight represented by 1, the weight of an equal quantity by measure of any other substance is compared with it. In the case of gases, air is taken for the standard of comparison, or for unity, and an equal quantity of any other gas is weighed, and compared with it. There are several methods of ascertaining the specific gravities of bodies. 1. One of the best, if the body is a Fig. 56. solid, is to weigh it in the air, and then in water, in a manner represented in Fig. 56. If the body weighs 100 grains in the air, and (50 grains in water, then, to ascertain its specific gravity, institute the following proportion: As 100 60, or 49 : 100 : : 1 ; 2.5; hence the sp. gr. of the body is 2.5, or two and a half times as heavy as water. If the solid is lighter than water, suspend to it a body heavier than water, whose specific gravity is known, and then weigh it as in the first instance. 2. To ascertain the specific gravity of liquids, the Areom- eter is a convenient instrument. It consists of a tube, A cubic foot of distilled water weighs 62.5 Ibs. 11 122 Nomenclature. a, (Fig. 57,) graduated with numbers, upon the end Fig- 57. of which are two balls, the lower filled with mer- U cury. If the instrument sink in distilled water to 1, it will sink below that mark in liquids which are lighter than water, and will remain above it .n those which are heavier. The specific gravity of each liquid is thus ascertained by the numbers I v ' on the scale. The specific gravity of liquids is also ascertained 5(H||jjl|IJi|^ by the use of a small bottle containing just 1000 grains of water; by filling it with any other liquid, its weight will express directly its specific gravity. 3. The specific gravity of gases is more difficult : a given portion of air is carefully weighed in a thin glass flask ; the air is then exhausted, and the flask weighed ; the difference gives the weight of the air ; this is taken for unity, and the weight of an equal quantity of any other gas is compared with it; thus, 100 cubic inches of dry air, at 60 F. and 30 in. barometer, weigh 31.0117 grains; 100 cubic inches of oxygen weigh 34.109 grains. Now, to ascertain the sp. gr. of oxygen, institute the following proportion : As 31.0117 : 34.109 : : 1, the sp. gr. of air, to 1.10:J.",, the sp. gr. of oxygen. The sp. gr. of any other gas may be found in the same way. Nomenclature. The study of particular substances has been greatly facili- tated by the introduction of the nomenclature. By the use of systematic names, expressive of the constitution of substances, the recollection of the name will call to mind the constitu- tion ; while, on the other hand, if there be any difficulty in remembering names, the constitution will at once show what the name must be. Hence, although compounds are very numerous, the student can have no difficulty in remembering their names and constitution, for the one necessarily suggests the other. The present nomenclature was introduced in 1787 by the French chemists. It resulted from the labors of Lavoisier, Berthollet, Guyton-Morveau, and Fourcroy. Since that time, it has undergone but a few slight changes. The former no- Nomenclature. 123 menclature, if such the entire want of system could be called, was barbarous in the extreme ; fanciful names were introduced, and often many such were attached to the same substance. I. Simple Substances. The names of such elementary sub- stances as had long been known, remain unaltered, as of gold, iron, etc. Those which have been discovered within the period of modern chemistry, have received names ex- pressive of some obvious property; thus the name oxygen signifies a generator of acids ; iodine, violet-colored, from the beautiful color of its vapor ; chlorine, green, from the color of the gas. The following are the names of the simple substances, with their symbols annexed : Oxygen, O. Chlorine, Cl. Iodine, I. Bromine, Br. Fluorine, F. Hydrogen, H. Nitrogen, N. Carbon, ". C. Sulphur, 8. Phosphorus, P. Boron, B. Silicon, Si. Selenium, Se. Potassium, (Kalium,) K. Sodium, (Natrium ) Na. Lithium, L. Barium, Ba. Strontium, Sr. Calcium, Ca. Magnesium, Mg. Aluminium, Al. Glucinum, .' G. Yttrium, Y. Thorium, Th. Zirconium, Zr. Manganese, Mn. Iron, (Ferrum,) Fe. Zinc,. ..Zn. Cadmium, Cd. Tin, (Stannum,) Sn. Cobalt, Co. Nickel, Ni. Arsenic, As. Chromium, Cr. Vanadium, V. Molybdenum, Mo. Tungsten, (Wolfram,) W. Columbium, (Tantalum,) Ta. Antimony y (Stibium,) Sb. Uranium, U. Cerium, Ce. Bismuth, Bi. Titanium, v .Ti. Tellurium, Te. Copper,'(Cuprum.) Cu. Lead, (Plumbum,) Pb. Mercury, (Hydrargyrum,) . . : .Hg. Silver, (Argentum,) Ag. Gold, (Aurum,) Au. Platinum, PL Palladium, Pd. Rhodium, R. Osmium, Os. Iridium, Ir. Latanium La Q.Acid Compounds. The names of acid compounds have a peculiar construction. All the acids formed by combination of oxygen with other substances, including a great majority of the whole number, take the name of the other substance, (which is called the base,) changing its termination. If there 124 Nomenclature. be two oxygen acids formed with the same substance, the stronger, which contains more oxygen, takes the termination ic, and the weaker, ous. In the case of more numerous acid compounds, the prefix hypo signifies inferiority, as in the following of oxygen with sulphur, beginning with the stronger, and proceeding to the weaker : Sulphuric acid, Sulphurous acid, Hyposulphuric acid, Hyposulphurous acid. Sometimes the prefix per is used to indicate an additional, but indefinite quantity of oxygen. Thus pirchluric acid contains more oxygen than chloric acid. Acids which do not contain oxygen receive names which >are compounded of the names of their constituents, the first enunciated terminating in o, and the last in ic ; as, chloro- carbonic acid. Often the first is shortened ; as, fluo-boric, in- stead of fluro-boric : this is the case with the hydrogen acids ; as, hydrochloric acid, hydrosulphuric acid. 3. Primary Compounds which are not Acids. In such com- pounds, the names are composed of the names of their con- stituents. In the compounds of oxygen, chlorine, iodine, bromine, and fluorine, with other substances, they are first enunciated, and receive the termination ide ; as, oxide of iron, chloride of iron, iodide of mercury, bromide of carbon, fluoride of zinc. In their compounds with each other, the order of enunciation is not essential, although it is com- monly that in which they are above mentioned; thus we may say, chloride of bromine, or bromide of chlorine; but the former is more common. Compounds of the other non-metallic substances with each other and with the metals, receive names of similar construc- tion, except that the termination urct takes the place of idc ; as, carburet of iron, bicarburet of hydrogen, sulphuret of arsenic. In many cases, one substance unites with another in several proportions, and the compounds are designated by numeral prefixes proto the first, bi (formerly dcuto was used) the second, fpr the third, ouadro the fourth, etc., and per the Nomenclature. 125 highest degree, but indefinite ; scsqui signifies one and a half. If, however, the last enunciated substance, or base, be in two or more proportions, the dividing prefixes di, tri y etc., are used; subsequi indicates one and a half of the base. The following table exhibits all the cases of the use of numeral prefixes : Triphosphuret of copper =1 equiv. phosphorus and 3 equiv. copper. of copper = 1 " oxygen and 2 copper. Subses.juiphospliuret of copper =1 " phosphorus and 1 copper. Protoxide of copper =1 " oxygen .and 1 copper. Sexjuinxide of manganese = ^4 " oxygen and 1 ' manganese. Binoxide of manganese =2 " oxygen and 1 manganese. Trriodide of nitrogen =3 iodine and 1 nitroen. Quad rochloride of nitrogen =4 " chlorine and 1 " nitrogen. Peroxide of iron = iron oxidated in the highest degree. Many metals, whose names terminate in urn, merely change ium or um into a to indicate the state of protoxide. Thus potassa protoxide of potassium, lithia protoxide of lithi- um, etc. The protoxide of calcium has long been known by the name of lime. Alloys, or compounds of metals with each other, not being yet reduced to the laws of definite proportions, have no sys- tematic names. Some primary compounds, whose combinations are analo- gous to those of simple substances, receive simple names, which in composition receive the termination uret, and follow the rules above given. These are ammonia and cyanogen. Another primary compound, water, forms compounds which are called hydrates ; as, hydrate of lime. 4. Secondary Compounds, or Salts. These are formed by the combination of acids with other primary compounds, which are called, in reference to them, bases. The name of a salt is composed of the names of the acid and base. If the name of the acid have a termination ic, it is changed into ate ; ous is changed into ite. Numeral prefixes are used according to the rules which have been given, as in the following ex- amples : Dinitrate of the protoxide of lead =r 1 cq. nitric acid and 2 eq. protoxide of lead. Protonitrate of mercury = 1 " and 1 " " of mercury. Sesqui-ulphate of potassa = 1 " sulphuric acid & 1 " potassa. Bisulphateof peroxide of mercury = 2 " " and 1 ' perox. of mercury. Tersulphate of alumina =3 " and 1 " alumina. 11* 1*26 Notation. As the acids never unite with the metals directly, but gen- erally with their oxides, and sometimes other compounds, in the case o/ the oxides, the name is abbreviated: thus, by protonitrate of mercury is always understood protonitrate of the protoxide of mercury. Also, the prefix proto is often understood, and we say, nitrate of mercury. There are many secondary compounds, little known, how- ever, except to the chemist, called sulphur salts, and haloid salts, whose nomenclature follows the rules of primary com- pounds which are not acid. Notation. Notwithstanding the great advantages of the chemical no- menclature, a much greater help is given to the student in the notation. By this, as in algebra, long and intricate pro- cesses are exhibited to the eye at a glance, and the relations of the constituents in complicated compounds easily compre- hended. Each element is represented by a symbol consisting of its initial, or, in the case of two or more which have the same initial, of the initial and one of the following letters, as on page 123, where the symbols of all the elementary substances are given. In the case of potassium, sodium, tin, iron, and several others, the symbols are derived from the Latin names. The symbols of compounds are composed of the symbols of their constituents, algebraically connected; as, Fe-|-Cl, chloride of iron. In primary compounds, the sign -(- is often omitted. Coefficients are used to show the number of equiv- alents; as, N-|-4C1, quadrochloride of nitrogen ; or, if several symbols are written together without the sign -)-, an index is substituted for the coefficient, because the coefficient multi- plies all which come between it and the next sign. Thus the symbol of the substance last mentioned may be written NCI 4 . Cyanogen, ammonia, and water, although compounds, have simple symbols, like the elements ; thus we have Cy, Am, and Aq, (Aqua,) instead of NC', H 3 N, and HO. Notation, 127 The symbols of oxygen and sulphur are abbreviated. The symbols for the compounds of oxygen are written thus : N for N + 5O, N for N + 4O, N for N.+ 3O, etc., each dot indicating an equivalent of oxygen. A comma is used in the same manner for the compounds of sulphur ; thus, P for PS. In place of the coefficient 2, a dash is often drawn through or beneath the symbol. This is very convenient in the case of half equivalents ; as, Mn, signifying 2Mn -|- 3O, that is, Mn-f- 1JO, sesquioxide of manganese. In compounds of compli- cated constitution, it is often necessary to multiply several terms by one number, or to connect them as a whole to another term. This is done, as in algebra, by the use of vincula or parentheses ; thus (K-(-2S)-{- Aq, shows that Aq is combined with K-)-2S, as with one substance; but if the parentheses were omitted, thus, K -|- 2S -j- Aq, the symbol would indicate a combination of three distinct substances, each one with the other. Also in 2(K+2S), the first coeffi- cient belongs to what is within the parentheses as to one substance. If the student will, for practice, explain the constitution and give the names of the compounds in the annexed table, he will become familiar with the rules of nomenclature and notation. The following table contains the names, equivalents, and symbols of the thirteen non-metallic elements, and the sym- bols of their compounds with each other, in the order in which they are described in this work : Oxygen, equiv. 8 ; symbol, O. Chlorine, 35.42 Cl, Cl + O, C1 + 4O, C1 + 5O, Cl -|-7O. Iodine, " 126.3 " I, I + 5O, I -f 7O, 3d -f I. Bromine, " 78 " Br, Br -f- 5O or BrO 5 . Fluorine, " 18.68 " F. Hydrogen 1 J H, H + O or H, H + 2O or H, H-f Cl, Hydrogen, $ H + 1, H + Br, H + F or HF. Nitrogen, 14.15 $ *> NO or N, NO* or N, N O 3 or N, NO< ^ or N, NO 5 or N, NCI 4 , NF, NH S . 128 Chemical Substances. Oxygen. c, c, c, c + ci,cci 5 , c*ci, cci 3 , rrK - fi 10 C1 i CH 2 , CH S , C, S'Cl, SCI, HS, ( HS, CS*. Phosphorus " 15 7 J P ' pl ' p3 ' P' 03 ' pSO5 > pSCI3 PSC15 P1 ' ' { P 8 ! 3 , PBr, P*Br, H 3 P S . Boron, " 10.9 " B, B-f- 3O, B-f-3Cl, B-f 3F. r Se, Se-f-O or Se, Se-f 2O or Se, Se4-3O Selenium, " 39.6 " Cor Se. Silicon, 22.5 Si, Si-j-O, SiCl, SiBr, SiS, SiF. CHAPTER I. CHEMICAL SUBSTANCES. + These substances will be arranged in three classes : 1st, non-metallic elements, and their primary compounds, with each other ; 2d, metals, with their primary compounds ; and 3d, secondary compounds, or salts. Class I. Non-metallic Elements and their Primary Com- pounds with each other. SECT. 1. OXYGEN. Symb .O. History. Oxygen was discovered by Dr. Priestley, of Eng- land, August, 1774, by exposing the red oxide of mercury to the solar focus. It was also discovered by Scheele, a Swe- dish chemist, in 1795, and the same year by Lavoisier, of Paris, neither being acquainted with the discovery by the others. The honor of the discovery, as is usual in such cases, is as- cribed to Priestley, who called it dephlogisticatcd air; Sheele gave it the name of empyreal air ; Condorcet, vital air ; and Lavoisier, oxygen. This latter name was suggested from the belief that it was the only acidifying principle in nature. It Pneumatic Cistern. 129 is derived from two Greek words,* signifying a generator of acids. It has since been found, however, that, although present in most acids, it is not the only substance capable of forming acid compounds. But, as a great majority of acids are oxygen acids, the name is not inappropriate. Natural History. Oxygen is the most abundant substance known. It forms of the atmosphere, f part of water. By far the greater part of the solid crust of the earth is composed of oxydized substances, and it will not be far from the truth, if we estimate oxygen to constitute f of all the matter with which we are acquainted.f Processes. Oxygen can easily be obtained from the oxides of metals, and from some of the salts. The oxides of man- ganese and of lead, and the chlorate of potassa, are most commonly used. The separation is effected by exposing these substances to a red heat, in an iron retort, connected by a pipe with the pneumatic cistern. For the collection of gases which are not absorbed by water, the Pneumatic Cistern is Fig. 55. generally employed. It consists of an oblong box, C, (Fig. 58,) made water-tight ; b b, two shelves to support re- ceivers, as r ; ID, a well filled with water, across which a board is placed, also to support receiv- ers, with small holes to let the gas through as it comes from the retort, which is placed over the side of the box. The shelves b b may be made for gasometers, or gas- holders ; and in that case they are boxes open at the bottom of the cistern, with stop-cocks passing through one corner in the top of each. These are made air-tight by a lining of sheet lead. When they are filled with water, the gas is in- troduced, by means of a lead pipe, through an aperture in the * * O^v$ and yirwitn. t If we suppose the sun and planets, with the stellary systems, to be composed of matter similar to our earth, the quantity of oxygen which actually exists must be immeasurably great. 130 Oxygen. side of each, near the bottom; as it rises up, it displaces the water; / is a lamp-stand and retort,* as it is connected with the cistern. t Theory. To understand the theory of the process by man- ganese, it is necessary to notice the composition of its three oxides. Manganese. Oxygen. Protoxide, 27.7 or I equiv. -f- 8 or 1 equiv. = 35.7 Sesquioxide, 27.7 " -f-12orli =39.7 Peroxide, 27.7 " -j- 1(i or 2 " = 43.7 The oxygen may be separated from the binoxide in two ways : 1. By simply exposing it to a red heat. In this case, the binoxide parts with equiv. of oxygen, and is converted into sesquioxide. 1 oz. of'manganese will yield 128 cubic inches of oxygen. 2. By putting it, in fine powder, into a glass flask, with an equal weight of concentrated sulphuric acid, and heating the mixture by a spirit lamp, the manganese parts with one equiv. of oxygen, and the sulprmte of the protoxide of manganese remains. About twice the quantity of gas is obtained by this process, 1 oz. yielding 256 cubic inches of gas. But the former method is most convenient in practice. For these processes, the manganese should be previously ascertained to be free from carbonate of lime, which yields carbonic acid gas on being heated. \ Oxygen obtained in this way is not quite pure, but is sufficiently good for all pur- poses of experiment. The gas obtained from chlorate of potassa is much purer, but more expensive. It may be easily obtained by subjecting the salt to a dull red heat in a green or white glass flask, made without lead, * Jletorts are either plain, as in Fig. Fig. 59. 58, or tubulated, as Fig. 59. A Florence flask will answer a good purpose, if a lead tube is fitted to it. See Fig. 60. t The cistern may be made of wood, / or, what is better, of copper, of any con- / - venient dimensions. One five feet long, \ twenty inches wide, and twenty inches in height, is sufficiently large for com- mon purposes. $ It may be freed from carbonate of lime by washing it in dilute hydrochloric acid. Physical and Chemical Properties. 131 or in an iron retort.* It first becomes liquid, and is then resolved into oxygen and chloride of potassium. Theory. The chlorate of potassa is composed of chloric acid and potassa, and the theory of the process may be thus explained : KO -|- CLO 3 are resolved into K-f-CL, which remains in the flask, and equiv. of oxygen, which are collected over the cistern. One ounce of chlorate of potassa will give about 640 cubic inches of oxygen. Physical Properties. Oxygen is transparent, colorless, tasteless, and inodorous. In the simple state, it always exists in the form of a gas. It cannot be condensed to a liquid or a solid, by pressure or cold. It refracts light the least of all substances ; is a non-conductor of electricity ; is the only substance whose electric state is absolutely negative; and of course it always goes to the positive pole in the galvanic circuit. Its specific gravity is 1.1026; conse- quently, 100 cubic inches, when the thermometer is at 60 Fahr. and the barometer at 30 inches, will weigh 34.1872 grains. It is a little heavier than atmospheric air. Chemical Properties. Oxygen possesses more extensive powers of combination than any other substance. It may be made to combine with all the simple substances. For acids and alkalies it has little affinity, because these substances have already received their proportion of it. Some of its combinations with the metals, and with combustibles, are very energetic. Erp. 1. Let down a pendent candle into ajar of the gas, (Fig. 61,) and it will burn with great brilliancy. * The iron retort is an iron bottle with a long neck. After the salt or the man- ganese is put into it, it may be placed in a furnace, and a lead pipe, as o or a, (Fig. 60,) adapted to the mouth, by means of a cork, a, a. The cork is first perforated by a hot, sharp iron, and en- larged, so as exactly to fit the tube, by a round file ; it is then pressed into the mouth of the bottle. The other end may then be conveyed to any part of the pneumatic cistern, or to the gas- ometers. This is the simplest mode of connecting apparatus together ; and it may be done either with glass or lead tubes. Fig. GO. 132 Oxygen. Theory. Fig. 62. Exp. 2. Blow out a candle, leaving a red wick, Fig. 61. and let it down into a jar of the gas, when it will be relighted with a slight explosion. This process may be repeated several times in rapid succession with the same jar of gas. Exp. 3. If a bit of lighted phosphorus, in a capsule, be immersed in this gas, (Fig. 62,) it will burn with great energy and intense brilliancy. Substitute for the phosphorus a small ball formed of turnings of zinc, in which a small bit of phosphorus is enclosed, and set fire to the ^phosphorus, as before. The zinc will be inflamed, and burn with a beautiful white light. Metallic arsenic, moistened with spirits of turpentine, and various other metals, in tine powder, may be burned in a similar manner. Homberg's pyrophorus flushes spontaneously, like inflamed gun- powder. Exp. 4. If iron wire, with a small lighted match attached "to one end, be let down into a tubulated bell glass of oxygen, it will burn rapidly ; and if a watch-spring be used, (Fig. 63,) the bell glass will be filled with beautiful star-shaped scintillations. Exp. 5. Or, let a stream of oxygen upon ignited charcoal, upon which is placed the end of a watch- spring ; it will burn with great brilliancy, and throw out immense numbers of the star-shaped scintillations. Exp. 6. Put a small bit of phosphorus into a test- glass tube, and fill the tube with warm water, so as to melt the phosphorus. Direct, now, a stream of oxygen gas from the gas bag, or a bladder, to which a tube is attached, upon the phosphorus. A brilliant combus- tion will be produced under water. All substances, by combustion in oxygen, increase in in iglit, in the proportion of about of a grain for every cubic foot ot Exp. 7. Fill the bowl of a tobacco-pipe with iron wire, coiled in a spiral form, and carefully .weighed ; heat the bowl of the pipe red hot, and then attach the pipe to a bladder filled with oxygen gas. Uy forcing a stream of the gas through the pipe, the iron will burn, and will be found, when weighed, to be heavier than before. When com- pletely oxidized, 100 parts of iron will gain an addition of about 30. Theory. In these experiments, the oxygen combines with the combustible substance, and forms a compound, which, being now oxidized, is incapable of further combustion. In case of the iron, an oxide is formed, the weight of which is exactly equal to that of the iron and the oxygen together. In case of the phosphorus, an acid is formed, which is absorbed by water, if present, or appears as a fine powder. The heat and light appear to arise from the condensation of the .gas.* * In the case of combustion, the common opinion that the matter is destroyed, is erroneous. If the products are collected, they will be found equal in weight to the substances burned. It is a universal law that no particle of matter is annihilated. Chlorine. 133 The combination of oxygen with other substances is called oxygcnation, and if the compound be an oxide, oxidation* Oxygen is slightly absorbed by several substances ; 100 cubic inches of water absorb three or four cubic inches of the gas. The relation of oxygen to animal life is very intimate and important. It is the only substance which will, for any length of time, support respiration. No animal can live without it. If confined in gases destitute of oxygen, death is the certain consequence. A few years since, 148 persons were confined in a prison called ' Black Hole,' in Calcutta, for a night, and, although there were two windows open in the west end of the building, only twenty-three were found alive in the morning. Pure oxygen gas is generally destructive to animal life. The animal confined in it lives too fast ; breathing becomes difficult, and if it remain for any time, death will ensue. If the quantity be small, it will support life longer than the same quantity of common air. A bird will live five or six times as long in a few gallons of oxygen as in the same quantity of confined air. In order to its most salutary effects, it should be diluted with nitrogen, as we find it in the atmosphere. The Creator has, in this respect, adapted it to the support of life, as any thing which destroys the relation thus established, renders it deleterious to the animal constitution. Uses. Oxygen has been used with good results in certain diseases, such as paralysis of the thorax, and general debility. Its effect upon the blood is to change it from dark red to a bright vermilion. SECT. 2. CHLORINE. cs u m v $ by vol. 100. o r, C 2.47 Air =1. Symb. Cl. Equiv. wgt . 35.43. p. Gr. ^ ^ Hyd =1 History. Chlorine was discovered by Scheele in 1774, and described under the name of dephlogisticated marine * It has been customary with many to call oxygen, and some other kindred substances, " supporters of combustion," while the substances with which they combine are called combustibles. But the supporters of combustion and the combustibles are alike essential to the combustion, and both are consumed in the process. Indeed, if the latter be in ex- 12 134 Chlorine. History. acid. The French chemists called it oxygenized muriatic acid, afterwards contracted to oxy-muriatic acid. This name implied a theory of its composition, suggested by Berthollet, that it was a compound of muriatic acid and oxygen. Gay Lussac and Thenard, in 1809, first suggested that it might be a simple substance. Sir H. Davy, after subjecting it to the most powerful decomposing agents, without in the least affecting its character, denied its compound nature, and maintained that, according to the true logic of chemistry, it should be regarded as a simple body. The views of Davy were for a long time combated. Drs. Murray and Thomp- son in England, and Berthollet, Gay I^ussac, and Thenard in France, engaged with great warmth in the controversy. But the name chlorine, suggested by Davy from a Greek word* signifying green, not implying any theory as to its nature, came gradually into use, and the contest subsided. It is now universally regarded as a simple substance. The introduction of chlorine into the class of simple bodies changed entirely the views of chemists relative to the theory of combustion. Previous to the discovery of oxygen, the Stahlian theory of combustion was generally adopted. According to this theory, combustion was the escape from combustibles of a certain principle called /j///w"-/>70//, which pervaded most bodies. Soon after the discovery of oxyirrn, Lavoisier made an attack upon the phlogistic, or Stuhli.in theory, and proved that combustion was produced by the union of oxygen with some combustible body. But when the properties of chlorine were investigated, and it was viewed as a simple substance, it was found to produce all the phenomena of combustion. Hence the theory of Lavoisier, that combus- tion was owing to the union of oxygen with a combustible, u us extended ; and the phenomena of combustion are not referred to any more specific cause than intensity of chemical action. Natural History. Chlorine is one of the constituents of common salt, and therefore exists in the ocean in large quan- tity. Other compounds in the mineral kingdom are numerous. cess, a portion of it will remain, while the former will be entirely con- sumed. Generally, the supporter of combustion, as it is called, is a gas which envelops the combustible ; but there is no scientific distinction. Physical and Chemical Properties. 135 Processes. 1. It may be obtained in the form of a gas, by the action of hydrochloric acid upon the binoxide of manga- nese. Take the latter, finely powdered, in a retort, and pour on twice its weight of concentrated hydrochloric acid. Collect the gas over the cistern in inverted bottles containing warm water, or, more conveniently, over a small cistern of warm water. The water should be raised to 70 or 80 Fahr., as cold water japidly absorbs the gas. Apply a moderate heat ; and, when the bottles are filled, they should be stopped with ground glass stoppers smeared with tallow. Theory. In this process, the binoxide of manganese is decomposed into protoxide and oxygen. A part of the acid combines with the protoxide, and another is decomposed, its hydrogen uniting with the oxygen, and forming water, and the chlorine is set free. In other words, the MnO 2 and HC1 are converted into MnO + HC1 ; and HO, which remain in the retort, and Cl, which comes over. 2. The cheapest mode of obtaining chlorine is the follow- ing : Put eight ounces of common salt, with three ounces of pulverized peroxide of manganese, and five ounces of sulphuric acid, diluted with equal weights of water, into a Florence flask or retort, and apply heat as before. The MnO 2 , Na + Cl, and 2SO 3 are converted into MnO-f SO 3 , NaO + SO 3 , and Cl. Physical Properties. Chlorine gas is of a greenish-yellow color ; has an astringent taste, and a disagreeable odor ; is a non-conductor of electricity, and goes to the positive pole in the galvanic circuit. By the pressure of four atmospheres, or 6;) Ibs. to the square inch, it is condensed into a yellow liquid, and into a solid by the reduction of the temperature below 32.* 100 cubic inches of this gas at 60 Fahr., and 30 barometer, w^igh 76.5988 grains. Chemical Properties. Chlorine unites with many sub- stances with great energy, producing combustion; but its range of affinity is more limited than that of oxygen. * Mr. Faraday succeeded in condensing it in a bent tube, sealed hermetically. The pressure is produced by the accumulation of the gas evolved by the affinities between the materials in the short end of the tube. The experiment is attended with the hazard of breaking the tube, and should not be attempted, unless the hands and face are protected. 136 Chlorine. Exp. 1. If a small lighted taper be immersed in a jar of the gas, the taper will burn for a short time with a small red flame, evolving large quantities of smoke, and then go out. The reason is, that the Rune is mostly composed of carbon and hydrogen ; the chlorine unites \vith the hydrogen, but not with the carbon ; the latter is therefore precipitated in the form of smoke, and soon puts the light out. Exp. 2. Into a tall glass vessel, filled with chlorine, throw finely- pulverized antimony ; the metal will burn as it falls through the gas. Exp. 3. A rag wet with oil of turpentine will instantly be inflamed, when immersed in the gas. Ksp. 4. Introduce phosphorus into ajar of chlorine; the phosphorus will soon ignite, and burn with a pale-green flame. Exp. 5. Instead of the phosphorus, drop in a few drops of liquid ammonia; the ammonia will be decomposed; a flash and a white smoke will be instantly produced. Several other metals and combustibles combine with chlo- rine with such energy as to exhibit the phenomena of com- bustion. Chlorine is readily absorbed by water. Recently-boiled water, when cold, absorbs twice its bulk, but gives it off when heated. Exp. Into a jar furnished with a well-fitted glass stopper, and filled with cold water, let up chlorine gas enough to displace half the water; stop it tight, and shake it, and most of the gas will be absorbed by the water. Open the jar under more cold water, which will rush into it to fill the vacuum occasioned by the absorption of the chlorine ; then re- peat the process once or twice, and the water will be saturated with chlorine, and possess most of its properties. If the water in this ex- periment be at the temperature of 32 Fahr., the chlorine will form a definite solid compound with it, in yellow crystals, which will be set n on the sides of the jar. The crystals are composed of 35.42 or 1 atom of chlorine, and 90 or 10 atoms of water. Chlorine forms with hydrogen, if the vapor of water be present, a mixture which explodes violently when exposed to the direct rays of the sun, or even in a bright day with- out such exposure. Ex. Mix, in a dark place, equal measures of hydrogen and chlorine. Expose the mixture to the light of day, and a slow action will take place. Cover the glass with a black cloth, to which a string is attached, and place the vessel in the direct rays of the sun. Remove the cloth by means of the string, taking care to have some object, as a door, be- tween you and the receiver; as soon as the rays of light strike the mixture, a violent explosion will occur, and an acid compound will be formed. Chlorine possesses remarkable bleaching properties. Exp. ]. Immerse in the gas strips of calico, flowers, etc., and they will be bleached in a short time ; or the saturated water may be used. Uses of Chlorine. 137 Exp. 2. Pour some of the saturated water into a small quantity of ink, and the color will be discharged; or put into it some writing, which will become invisible, but will be restored if immersed in a solu- tion of prussiate of potassa. Printers' ink will not be affected ; and hence chlorine water may be used for removing blots from books. Chlorine is not an acid; for it does not redden vegetable purples, and it combines directly in definite proportions with the metals, which is not true of any acid. It is not alkaline. Chlorine is very destructive to animal life. A few bubbles of gas, in the atmosphere of a room, will bring on coughing. Half a gill undiluted in the lungs would cause death. If diluted largely with air, it irritates the throat and lungs, and if pure, destroys their texture. Pelletier is said to have fallen a victim to its effects. The antidote is ammonia. Use*. 1. Thf bleaching properties of chlorine are turned to great account in the art of bleaching. Both the gas and the water saturated with it were employed as early as 1784-5 for bleaching cloths ; but it proved injurious to the workmen. In 1789, the gas was condensed in a solution of pearlashes, and went by the name of " Liquid javelle." But this sub- stance soon gave place to Mr. Tennant's preparation of the chloride of lime, in 1798. Since that period, most of the bleaching of cotton and linen goods has been effected by this substance. The articles to be bleached are first steeped in hot water, boiled in a weak alkali, and then immersed in a solu- tion of the chloride of lime. They are next taken out, and washed in water ; sometimes diluted sulphuric acid is applied to increase their whiteness; and, finally, they are boiled in pearlashes and soap, to render them free from the odor of chlorine. Chloride of soda, magnesia, and potassa, are some- times used, but they are more expensive.* Theory. The theory of this process, perhaps, would be better un- derstood after learning the composition of water; but it can be given * The advantages of this mode of bleaching, over the one formerly employed, are very great. By the old method, large fields in the vicinity of every manufactory were devoted to the purpose of spread- ing- the cloths. These fields are now devoted to agriculture. It re- quired also several weeks, and even months, to complete a process which may now be performed in as many days. In the former case, they were dependent upon the light of the sun and fair weather ; in the latter, they are independent of the weather, and of the seasons of the year. 12* 138 Chlorine and Oxygen. here with a little explanation. Water is necessary to the bleaching effects of chlorine. It is composed of oxygen and hydrogen. The chlorine, having a strong affinity for the hydrogen, decomposes the water, and leaves the oxygen to combine with the coloring matter. The coloring matter may also contain hydrogen, and thus be directly decomposed by the chlorine. The coloring matter is rendered soluble by combination with oxygen, and is removed by the alkali. The pro- cess of bleaching by chlorine is but one out of many useful con- tributions of science to art. 2. Another use of chlorine arises from it* difinfrcting agency. It seizes hold of every species of animal and vege- table effluvia, and decomposes them. Hence its utility in contagious diseases. The chloride of lime is used for this purpose. Moisten the dry chloride with water, and place it in the infected apartment, which will soon be purified. It is thus very useful for dissecting-rooms, for cleaning drains, sewers, vessels, and even the atmosphere, when charged with miasma. Its use in medicine is mostly confined to the puri- fication of apartments of the sick. The chloride of sod;i is, however, used in certain cases of inflammation, such as ulcers, mortification, and cutaneous diseases. It is also used as a wash for the teeth.* The compounds of chlorine with the metals are called chlorides. Chlorine and Oxygen. The compounds of chlorine and oxygen are held together by very feeble affinities, and are never met with in They cannot be made to combine directly, unless they are in the nascent state, that is, at the instant of their formation. Hypochlorous Acid. Symb. Cl + O or CIO. Equiv. 35.42 -f 8 = 43.4 Sp. gr. 3.0<2l2. It was discovered by H. Davy, in 1811, and called euchlorine from its being of a brighter color than chlorine. Preparation. Put two parts of the chlorate of potassa and one of hydrochloric acid into a retort, and apply the heat of water under 200 Fahr. Collect over mercury ; or it may be more conveniently prepared for experiment by placing the materials in a flask, * So many and great are the advantages of cleanliness and pure air, that chloride of lime should be kept in every family, especially in cities and large towns ; but an apartment in which it has been used should be thoroughly ventilated before it is again occupied, or weak lungs may be seriously injured. Chlorine and Oxygen. 139 Fig. 64. a, (Fig. 64,) connected by a glass tube, bent twice at right angles, with a tall receiver, b. Apply heat as before ; the gas, being heavier than the air. will displace it, and fill the receiver. Theory. The hydrochloric acid and the chlo- ric acid in the chlorate of potassa mutually decom- pose each other, and the results are water and the hypochlorous acid. 2 equiv. HC1, and one of KG -|- CIO 5 , are converted into KO, 2 Aq, and 3C1O. If the gas be collected over mercury, the chlorine unites with the mercury, and the acid remains in a pure state. Properties. Greenish yellow color, more brilliant than chlorine ; odor like burned sugar ; absorbed rapidly by water, ;uid gives to it an orange color; bleaches vegetable sub- stances; gives vegetable blues a red tint before destroying them ; does not unite with alkalies, and hence has been con- sidered as a protoxide of chlorine; highly explosive, the heat of the hand being sufficient often to explode it. Many sub- stances take fire in it spontaneously. Erp. A rag dipped in spirits of turpentine will kindle in it with a slight explosipn. /.//>. Phosphorus explodes in it spontaneously. Fifty measures of this gas, and eighty of hydrogen, form an explosive mixture. C' dorms Acid. Symb. C1 + 4O, or CIO 4 . Equiv. 35.42 -f .\l 67.42. Sp. gr. 2.3374. Discovered by Davy, in 1815, and soon after by Count Stadion, of Vienna, and has been heretofore described as peroxide -of chlorine. Pn partition. Make a paste of strong sulphuric acid and chlorate of potassa ; put it into a retort, and apply the heat of warm water under 212 Fahr. Collect over mercury, or as in Fig. 64. For the purposes of experiment, take a wine or champagne glass, and put into it a few grains of chlorate of potassa; then pour on sulphuric acid; the gas will soon fill the glass. As the gas often explodes spontaneously, this is the safest mode of collecting it. The preceding compound may be formed in the same way. Properties. Color, bright orange-green, richer than the preceding- compound ; aromatic odor ; is absorbed rapidly by water, and gives it its peculiar color; bleaches powerfully, and is more explosive than hypochlorous acid. Exp. Put a bit of phosphorus into a wine glass filled with the gas. It will instantly ignite, with a slight explosion. Chloric Acid. Symb. Cl -f 5O, or CIO 5 . Equiv. 35.42 + 40 75.42. It was first noticed by Mr. Chenevix, and ob- tained in a separate state by Gay Lussac. 140 Iodine. Preparation. To a dilute solution of chlorate of baryta add dilute sulphuric acid sufficient^ combine with the baryta. Pure chloric acid will remain after the baryta subsides. Theory. The sulphuric acid has a stronger affinity for baryta than the chloric acid with which it has combined, decomposes it, and leaves the chloric acid. Properties. Sour to the taste; reddens vegetable blue colors, but possesses no bleaching properties, by which it is distinguished from the preceding compounds. It may be concentrated by gentle heat into an oily liquid of a yellow tint, emitting the odor of nitric acid. In this state, it sets fire to paper and dry organic matter, and converts alcohol into acetic acid. Perchloric Acid. Symb. Cl + 7O or CIO 7 . Equiv. 35.42 -f 56 = 91 .42. Sp. gr. 1 .65, water = 1 . It was first described by Count Stadion, of Vienna. Process. It may be obtained by heating a mixture of I part of water, 3 of sulphuric acid, and 5 of perchlorate of potassa. At a teni|M-r:iiiii<' of 284, white vapors arise in the receiver, which are soon condensed into a colorless liquid. By admixture with sulphuric acid, and distillation, it crystallizes in elongated prisms. It is a very stable compound ; absorbs moisture from the air powerfully, and boils at 392 Fahr. When thrown into water, it hisses like red-hot iron. SECT. 3. IODINE. 70g Ajr =1 History. Iodine was discovered in 1812, by a manu- facturer of saltpetre M. Courtois, of Paris. The substance in which it was first noticed, was the residual liquor after the preparation of soda from the ashes of sea-weeds. This dark- colored liquor possessed the peculiar property of powerfully corroding metallic vessels ; on the application of sulphuric acid, life noticed that it threw down a dark-colored substance, which was converted into a violet-colored vapor on the ap- plication of heat. This attracted his attention, and he gave some of it to M. Clement, who, in 1813, described it as a new body. Gay Lussac and Davy soon after proved it to be a simple non-metallic substance, analogous to chlorine. The Physical Properties. 141 name iodine is derived from a Greek word,* significant of the beautiful violet color of its vapor. Natural History. Iodine exists in nature but in small quantities. It is found mostly in sea-weeds, in sponges, in the oyster and some other mollusca, in many salt and mineral springs, both in Europe and America. Vauquelin found it in combination with silver ; marine animals and plants derive it from sea-water. Most of the iodine of commerce is obtained from the impure carbonate of soda, called kelp. This is nothing but the ashes of sea-w.eed, great quantities of which are prepared on the shores of Scotland. Iodine exists, in combination with sodium and potassium, in the liquor which is left after the carbonate of soda crystallizes. Process. Iodine may be obtained by lixiviating the pow- dered kelp in cold water. Evaporate the lye till the car- bonate of soda crystallizes ; take the residual liquor, and evaporate it to dryness ; pour on to this J its weight of sul- phuric acid ; it may then be put into a common retort, to which is attached a globe receiver, and the retort heated; violet-colored fumes will soon arise, and be condensed in the receiver, in the form of opaque crystals, of a metallic lustre. These are to be washed in water, and dried on a filter of unglazed paper. Physical Properties. Iodine, at the common temperature, is a soft, pliable, opaque solid, of a bluish-black color, and of a metallic lustre. It is generally fouftd in small crystalline scales, resembling micaceous iron ore, or the scales from a smith's forge. But it may be made to crystallize in large rhomboidal plates, whose primary form is a rhombic octohe- dron, by saturating hot alcohol, or hydriodic acid, with it, and evaporating in the open air. It is very acrid to the, taste, and has the odor of chlorine. Like O and Cl, it is a non-conductor of electricity, and goes to the positive pole in the galvanic circuit. It acts as a powerful poison to the animal system; fuses at 225, and boils at 347 Fahr. If moisture be present, it volatilizes at the common temperature, 142 Iodine. and sublimes rapidly under 212. The rich violet vapor of iodine is remarkably dense, more than eight times as heavy as air. One hundred cubic inches would weigh 269.8638 grs. Exp. This vapor may be shown by putting a few grains of the iodine into a gloss flask, and applying a gentle heat. Chemical Properties. Iodine has an extensive range of affinity. Like chlorine, it destroys vegetable colors, though in a less degree, and, like oxygen and chlorine, it unites directly with the metals and with non-metallic combustibles with great energy. Exp. Drop a bit of phosphorus upon a few grains of iodine, con- tained in a wine-glass, and it will be instantly inflamed. The compounds thus formed resemble those of oxygen and chlorine. It has little affinity for metallic oxides. It is not inflammable, but a supporter of combustion. The im- ponderables have no effect to change its character, and hence it is regarded as a simple body. It is largely soluble in alcohol, and but sparingly soluble in water, requiring seven thousand times its weight of water for solution. Tests. Starch is a very delicate test of iodine. It gives to the solu- tion a deep blue color. A liquid containing f^v\FW part of its weight of iodine, receives a blue tinge from a solution of starch. Iodine is sometimes adulterated with black lead. This may be de- tached by dissolving it in alcohol, when the lead will not be held in solution. Uses. Used in medicine in the form of a hydriodate of potassa, for certain glandular diseases. The goitre is a kind of wen growing from the neck* which is very common in Switzerland, in the treatment of which iodine has been of great service. Its vapor is irritating to the lungs, and produces copious secretions in the eyes and nostrils. The compounds of iodine with non-metallic combustibles are termed iodurcts ; its compounds with the metals, iodides. Iodine forms with oxygen three, perhaps four compounds : 3. lodic acid, 1 eq. 1, 126.3 + 5 eq. O, 40=166.3 eq. Symb. I + 5O or lO*. 4. Periodic acid, 1 eq. I, 126.3 + 7 eq. O, 56=182.3. Symb. I + 7O or IO 7 . Bromine. 143 The first two compounds, oxide of iodine and iodous acid, are yet doubtful. The first is described by M. Sementini, of Naples, and the second by Mitscherlich. The oxide is a yellow solid, and the acid a similar liquid, but their properties have not been examined. lodic Acid was discovered by Davy and Gay Lussac about the same time. Davy, who first obtained it in a pure state, called it oziodine. Preparation. When iodine is brought in contact with the hypochlo- roua acid, two compounds are formed. The one is a volatile orange- colored substance, chloride of iodine, and the other a white solid, which is iodic acid. Apply heat to expel the chloride, and the iodic acid re- mains in a pure state. (See Turner, for other processes.) In this statr, it is anhydrous iodic acid, that is, destitute of water. Properties. It exists as a white, semi-transparent, crystal- line solid, of a strong, astringent, sour taste, and no odor; fuses at 500 Fahr., and is resolved into oxygen and iodine. It is soluble in water, with which it combines, and forms hydrous iodic acid ; deliquesces in moist air ; reddens vege- table blues, and finally destroys them. With charcoal, sul- phur, sugar, and similar combustibles, it forms detonating mixtures. Periodic, Acid was discovered by Ammermuller and Mag- nus, and is obtained from the periodate of silver, by adding cold water. It has decided acid properties, and is analogous in composition to perchloric acid. Chloriodic Acid was discovered by Davy and Gay Lussac. It may be formed by the direct union of chlorine and iodine. If the iodine is fully saturated with chlorine, it forms a yellow solid ; but if the iodine is in excess, the color is a reddish orange. It is easily fused, and converted into vapor ; deli- quesces in the air ; forms a colorless solution in water ; very sour to the taste ; reddens vegetable blues, and finally de- stroys them; does not unite with alkalies, and hence has been considered a chloride of iodine. Souberaine has lately distinguished a compound of 3 eq. of chlorine and 1 of iodine. SECT. 4. BROMINE. 8,-nb.n, E, History. Bromine was discovered in 1826, by M. Balard, a young French chemist, of Montpellier, who named \tmuride, 144 Bromine. because obtained from the sea ; but, in order to correspond with chlorine and iodine, it was called bromine, from a Greek word,* signifying rank odor. Natural History. It exists in nature in very small quan- tities. It is found in sea-water and marine plants, combined with sodium and magnesium. It is found in every sea whose waters have been tested for it, and in many mineral and salt springs. Process. It is obtained by passing a current of chlorine gas through the bittern of sea-water, and agitating the liquor with a portion of sulphuric ether. The ether dissolves the bromine, from which it receives a beautiful hyacinth-red tint, and, on standing, rises to the surface. Agitate this solution with caustic potassa, and the bromide of potassium and bro- mate of potassa will be formed. Evaporate the liquor, and the bromide of potassium will be left, from which the bromine may be distilled. Physical Properties. Bromine, at common temperatures, is a deep reddish-brown colored liquor, of a disagreeable odor and caustic taste; and, like oxygen, chlorine, and iodine, is a non-conductor of electricity, and a negative electric ; boils' at 116.5 Fahr., and congeals at -4 Fahr. into a brittle solid. It volatilizes at the common temperature and pressure. Exp. This may be shown by pouring a few drops of the liquid into a glass flask; it will soon be converted into a beautiful vapor, some- what resembling the vapor of iodine, having a density of 5.54. 100 cubic inches at 00 Fahr. should weigh 167.5158 grains. Chemical Properties. Its chemical properties are very analogous to those of chlorine and iodine. It readily bleaches litmus paper, and discharges the blue color of indigo. A lighted taper burns for a few moments in the vapor of bro- mine, with a flame green at its base and red at the top, and is then extinguished. Bromine unites with great energy with many combustibles. Exp. Pour a few drops of bromine into a strong wine-glass, and then pour upon it tin or antimony, in fine powder, from a glass fastened to Fluorine. 145 the end of a long rod ; the metals will be instantly inflamed. If potas- sium be used, it will cause a violent explosion. Bromine is soluble in water, alcohol, and ether ; the latter is the best solvent. With water at 32 F., it forms a hydrate, in crystals of a fine red color. It gives to a solution of starch an orange color. Chlorine will displace it from all its com- binations with hydrogen. It acts powerfully upon the animal system, and is very poisonous ; a single drop upon the beak of a bird, destroys it instantly. Bromic Acid (Symb. Br-f-50 or BrO 5 . Equiv. 78.4 -f- 40 = 118.4,) may be obtained by pouring sulphuric acid upon a dilute solution of bromate of baryta, and evaporating the solution. Properties. It has scarcely any odor, acrid to the taste, though not corrosive. It first reddens litmus paper, and then destroys the color. Chloride of Bromine may be formed by transmitting a current of chlorine through bromine, and condensing the disengaged vapors by a freezing mixture. It is a volatile liquid, of a reddish-yellow color, less brilliant than bromine. Its vapor is a deep yellow, taste very dis- agreeable, and odor penetrating, causing a discharge of tears from the eyes. Soluble in water which possesses bleaching properties. Bromides of Iodine. Bromine and iodine unite and form two com- pounds. Tlu> prnto-lromide is a solid easily converted by heat into a reddish- brown vapor, which, on cooling, is condensed into crystals of the same color, and of a form resembling fern leaves. By the addition of bro- mine to these crystals, they are converted into a liquid resembling a strong solution of iodine and hydriodic acid; but the nature of it is not satisfactorily established. SECT. 5. FLUORINE. Symb. F, Equiv. 18.68, eq. vol. 100. Fluorine is a name applied to a substance which has not as yet been obtained in a simple state. It is inferred from the nature of its compounds to be similar to oxygen, chlorine, bromine, and iodine. It has a strong affinity for hydrogen and the metals. . Natural History. It exists abundantly in nature, in fluor- spar combined with calcium, (fluoride of calcium.) Baudri- 13 140 Hydrogen. mont is said to have obtained it, mixed with hydrofluoric and fluosilicic acid gases, by treating a mixture of fluoride of cal- cium and peroxide of manganese with strong sulphuric acid. It appears to be a gaseous body, similar to chlorine. SECT. 6. HYDROGEN. Symb. H. C 0.0689 Air Jl. Hyd. History. The name hydrogen is formed from two Greek words,* and means a generator of water. It was known for many centuries, but was first distinctly described by Mr. Cuv- endish, in 1776. Nine years previous, Dr. Black discovered carbonic acid gas, which was the first gas discovered, except the atmosphere, and hydrogen was the second. Natural History. Hydrogen is a very abundant substance. It forms part by weight of water. Its chief repository, therefore, is the ocean ; but it is widely disseminated through the animal, vegetable, and mineral kingdoms. It ij of most liquids. Processes. 1. Water is always employed for obtaining hydrogen. It is composed of oxygen and hydrogen, and the object is to decompose it by presenting some substance, with which the oxygen will combine, and leave the hydrogen to escape in the form of a gas. Iron is such a substance, and will decompose the water slowly at common temperatures ; the oxygen combining with it, and forming the well-known substance called iron rust. But if the temperature of the iron be raised to 1000 Fahr., and the va- Fig. 65 por of water passed over it, it will de- compose it more rapidly. For this purpose, clean iron turnings, or bright iron wire, are pla- ced in the centre and Processes Theory, 147 of a gun-barrel, C, (Fig. 65,) open at both ends, and passed through a furnace, b. Into one end the vapor bf water is made to pass from the retort a, and the other end is con- nected by a lead pipe with the pneumatic cistern. As the v;ipor passes over the iron, its oxygen combines with it, and its hydrogen passes over into the receiver A.* ~. It is more conveniently obtained by putting small pieces of zinc,t or iron turnings, into a glass or lead retort, and pouring on one part of sulphuric acid, diluted with four pirts by weight of water, and collecting as above. Theory. In this process, the oxygen of the water unites with the zinc, and forms oxide of zinc, which combines with the acid, while the hydrogen of the water escapes. This was formerly supposed to be a case of what was called disposing affinity, in which the acid disposed the oxygen and zinc to unite, that it might combine with the compound ; for it has no affinity for them separately. This is sufficiently absurd. The process commences with zinc and water alone, without the aid of the acid, and is immediately arrested by the forma- tion of a coat of oxide of zinc, which protects the zinc from the action of the water. The acid dissolves away this coat- ing of oxide as fast as formed, and thus the action of the metal and the water is uninterrupted. For every nine grains of water which are decomposed, one grain of hydrogen will be set free. Eight grains of oxygen will unite with twenty-eight of iron, forming thirty-six of the protoxide of iron. One ounce of iron will yield 782 cubic inches, and one ounce of zinc 676 cubic inches of hydrogen. Impurities. The hydrogen, obtained in these processes, is not quite pure. That from the iron contains a volatile oil, produced by the hy- drogen and the carbon in the iron; this may be removed by passing the gas through alcohol. When zinc is employed, (and it is generally * If the water and the iron are weighed before the experiment, and the iron and the hydrogen after itthe increase in the weight of iron and the weight of the hydrogen is just equal to that of the water. Jn this way the" exact composition of water is determined analytically, and is found to be 8 parts of oxygen to 1 of hydrogen, and 1 vol. of the former to 2 of the latter. t The zinc may be conveniently prepared by pouring a stream of the melted metal into cold water. 148 Hydrogen. Physical Properties. preferred,) the impurities result from the sulphur which it generally contains hydrosulphuric acid is formed, and there are also traces of metallic zinc and carbureted hydrogen. These, except the last, may be removed by passing the hydrogen through pure potassa. VYhvn hydrogen of great purity is required^ distilled zinc should be used. Physical Properties. Hydrogen gas is colorless, tasteless, and, when perfectly pure, inodorous. - But as it is generally obtained, it has a fetid odor, arising from the oily matter which it contains, and the hydrosulphuric acid. It is a pow- erful refractor of light, and has never been condensed to a liquid. It is the lightest body in nature. It is sixteen times lighter than oxygen, 36 times lighter than chlorine, 200,000 times mercury, and 300 000 times lighter than Tig. 66. lighter than platinum \ Exp. Fill a gas bag with hydrogen,* (Fig. 66;) con- nect it with a bubble-pipe, and inflate soap bubbles with the gas; they will ascend rapidly, being forced up by the superior weight of the air. Or, if a jar of hydrogen be removed from the cistern, and inverted in the open air, the gas will immediately escape. In consequence of its extreme lightness, hydrogen is used for filling balloons. * The method of filling gas bags with gases from the pneumatic cistern, is repre- sented in Fig. 67. b is the cistern contain- ing water ; the receiver has a stop-cock in its top, upon which another stop-cock, C, connected with the bag a, may be screw- ed. The receiver is filled with gas, and, the stop-cocks being both open, is pressed down into the well, and the water presses the gas into the bag. Then, by closing both stop-cocks, the bag may be removed from the receiver. Fig. 67. Chemical Properties. 149 Aerostation. Roger Bacon first suggested the pos- Fig. 08. sibility of navigating the air by mechanical contri- vances; but nothing of consequence was effected until 17d2. The substance first employed to raise balloons was rarefied air, confined in a silk bag. Since the discovery of hydrogen, it has been universally cm- ployed for this purpose. Balloons are made of various hh;i[>rs and capacities. The spherical form (Fig. 68) is the best, for the reason that a given quantity of can- vass, or silk, made in the form of a sphere, will contain more than any other form, and hence offers the least resistance to the air. The substance employed for bal- loons is either varnished silk or gold-beaters' skin, and the size varies from 1 to 40 feet in diameter. They are generally covered with a net, n, connected by cords to & small boat, c, in which the aeronaut i stationed when he ascends. The hydrogen is prepared by putting iron turnings, sulphuric acid, and water, into several large casks, and connecting each with the balloon ; the hydrogen is then rnpidly evolved, and the balloon tied down until ready for use. Chemifcd Properties. Hydrogen has a strong affinity for many substances, and the energy of its combinations fre- quently produces the phenomena of combustion. Hydrogen is a combustible body, but not a supporter of combustion. Exp. Plunge a lighted taper into an inverted jar of hy- Fig. 69. drrvren ; the gas will instantly be inflamed at the mouth of tiie jar, and burn with a blue light; but the taper, if wholly immersed in the gas, will be extinguished, and relighted uurities. ~ The acid of commerce is not quite pure, containing the chloride of iron, and chlorine. This -MVCS the liquid a yellow color; but, \vhen perfectly pure, it is limpid. Hydriodic Acid. Symb. II + 1. Eq. 12G.3 + 1 = 127 .:*. Sp. gr. 4.3854, air=:l. Discovered by Gay Lussac, of Paris. Preparation. It may be obtained by passing iodine vapor and hydrogen gas through a red-hot porcelain tube. But a more convenient process, by which it may be obtained lor the purposes of experiment, is to put a small bit of phosphorus into a glass tube, filled with water, and drop upon it a few grains of iodine. Theory. The iodine unites with the phosphorus, forming the periodide of phosphorus, and then the water and the periodide mutually decompose each other. The oxygen of * The fact being established that hydrochloric acid is composed of hydrogen and chlorine, the old theory that oxygen was the only acidifying principle is proved false; there are many acids of hydrogen which have no oxygen in them. They are called hydracids. Hydrofluoric Acid. 157 the water unites with the phosphorus, and the hydrogen with the iodine, giving rise to phosphoric and hydriodic acids ; the latter passes over in the form of a colorless gas, and may be collected in a receiver of common air ; it may be passed through water, and absorbed by it. It cannot be collected over mercury, because it acts upon it. Properties. Hydriodic acid is a colorless, transparent gas, very sour to the taste, anil gives an odor like hydrochloric acid ; reddens vegetable blues without destroying them, and, when mixed with air, produces dense white fumes ; has a strong affinity for water ; is decomposed by several of the metals, such as potassium, sodium, zinc, iron, and mercury, and even when exposed to the air. Uses. This acid may be employed to form pigments. EJ }>. Take some of the salts of lead (acetate or nitrate of lead) in solution, and pour on hydriodic acid; it will decompose the salt, and form paints of a yellow color. Tests. The most delicate test of this acid is bichloride of platinum, a single drop of which, in solution, will give to a liquid containing the acid, a reddish-brown color, and a dark precipitate will subside. Exp. Starch is also a sure test. A few drops of sulphuric acid will give to a solution of the acid, mixed with a cold solution of starch, a blue color. Hydrobromic Acitl. Symb. Br + H or BrH. Eq.78.4 + J 79.4. Sp. gr. 2.735-3. Discovered by M. Balard, and may be obtained by immersing a red-hot iron into a mixture of the vapor of bromine and hydrogen ; the combination takes place slowly, without explosion ; or it may be formed, for ex- perimental purposes, by a process similar to that for obtaining hydriodic acid, using bromine instead of iodine. Properties. It is colorless, with an acid taste and pungent odor ; irritates the glottis, so as to excite couching ; exposed to moist air, it yields white dense vapors, and is rapidly absorbed by water ; decom- posed by chlorine instantly ; nitric acid also effects its decomposition. Hydrofluoric Acid. Symb. F + H or FH. Eq. 18.68 -(- 1 = 19.68. Sp. gr 1.0609. History. First procured in a pure state in 1810, by Gay Lussac and Thenard. Process. It is formed by the action of sulphuric acid on fluor-spar, ( fluoride of calcium.) This mineral is pulverized, 14 158 Nitrogen. put into a lead or silver retort, with twice its weight of sul- phuric acid, and heat applied. The acid will distil over, and must be collected in a vessel of the same material, surrounded with ice, to condense the acid. Theory. The hydrogen of the water in the sulphuric acid combines with the fluorine in the mineral, and the oxygen with the calcium ; the sulphuric acid unites with the oxide of calcium : the products are hydrofluoric acid, and sulphate of the protoxide of calcium. Ca, F, SO 3 and HO are converted into CaO + SO 3 and FH. Properties. At 32 F. it is a colorless liquid, and remains in that state at 59 3 , if preserved in well-stopped bottles; but, exposed to the air, it assumes the gaseous form, unites \\ itli the water of the atmosphere, producing white fumes. Its affinity for water is greater than strong sulphuric acid. Its vapor is much more pungent than chlorine or any of the irri- tating gases; the most aeffnto&NW to animal matter of any known substance, a single drop of the concentrated acid causing deep and almost incurable ulcers. It is distinguished for the remarkable property of acting on glass. It readily dis- solves silex, and an acid is produced called the Jtuo-silicir. acid; and hence it cannot be preserved in glass vessels. Uses. It is used for etching on glass. Exp. For this purpose, prepare some resin or beeswax, and form a coat over the glass ; then, with a pointed instrument, remove the coating where you wish the glass to be etched ; ponr on the acid, and in a few minutes the etching is completed. Then, by wash- ing the glass in water, and removing the coating, the figures will appear. The liquor in the retort will answer for this experiment, es- pecially if used within a day or two after the acid and the fluor-spar are mixed. SECT. 7. NITROGEN. Sym ,,N. E,ul T .{* ;',,. Bp. P . {* ft, = j; History. Nitrogen was discovered by Dr. Rutherford, of Edinburgh, in 1772. Three years after, Lavoisier discovered that it was a constituent of the atmosphere. Scheele also made the same discovery. It was called by Lavoisier azote, (from two Greek words,*) because it deprived animals of life ; but this is not the only gas which is azotic. Its present name, nitrogen, is derived from nitre, (nitrate of potassa.) * A and <, Physical and Chemical Properties. 159 Natural History. Nitrogen exists in all animals, in fun- gous plants, and constitutes of the atmosphere; also in some hot springs in Scotland, and in the Alps. It is also evolved from certain springs in the state of New York. Process. It may be obtained from the atmosphere, either by burning out the oxygen of a confined portion of air with some combustible, or by abstracting the oxygen in a more gradual way, by its affinity for some of the simple substances. Exp. 1. Put a small piece of phosphorus in a cup which will float on water, (Fig. 74,) and invert over Fig. 74. it a receiver of common air. On igniting the phos- phorus, it will unite with the oxygen, ana burn until all the oxygen is consumed, forming white fumes the pyrophosphoric acid. This acid, in a short time, will be absorbed by the water, which will rise and fill the jar J- full. This is sufficiently pure for common experiments, but contains vapor of phosphorus and carbonic acid, which may be removed by passing the gas through pure potassa. Exp. 2. Make a paste of flowers of sulphur and iron filings, and invert over it a receiver; the oxygen will combine slowjy with the iron, and leave the nitrogen. A stick of phosphorus will produce the same ef- fect. If the proto-sulphate of iron, charged with the binoxide of nitro- gen, be substituted for the paste, the process is more rapid. Exp. 3. It may also be obtained by pouring nitric acid on fresh muscle, and subjecting it to a moderate heat. Theory. On account of the strong affinity of oxygen for these substances, it leaves the nitrogen, and combines with them. Physical Properties. Nitrogen is colorless, tasteless, inodorous, not condensed into a solid by pressure or cold. 100 cubic inches weigh 30.1650 grains. Chemical Properties. Water, recently boiled, absorbs 1 J volumes of the gas. Nitrogen will not support combustion. Exp. Put a lighted candle into a jar of it, and it will be immediately extinguished ; hence it does not snp/tort Respiration. No animal can live in it, not because of the active properties of the gas, but because it excludes the oxy- gen. . It kills by its negative properties, for which it seems alone to be distinguished. The effect is like that of drowning. Nature of Nitrogen. Nitrogen has been supposed by 160 Nitrogen and Oxygen. some, among whom is Berzelius, to be a body compose J o" oxygen and an unknown base. But this base has never been exhibited in a separate state ; and, until that is done, it must be regarded as a simple substance. Although pure nitrogen is the most inert of substances, some of its compounds are among the most active and useful. Nitrogen and Oxygen. Common Air. Symb. 2N + O. Equiv. 28.30 + 8 = 36.30, eq. vol. 4N+O. Sp. gr. = 1. Th6 earth is sur- rounded by a gaseous fluid or atmosphere, consisting chiefly of common air, extending about forty-five miles from its sur- face, and revolving with it around the sun. Physical Properties. The atmosphere is a permanent, elastic fluid, transparent, inodorous, and tasteless. The air is very compressible. and elastic EXD. The compressibility of the air may be shown by the fire-syringe, by which it may be compressed into a very small compass. If 100 measures of confined air, under pressure of 1 lb., be subjected to double the pressure, or 2 Ibs., it will be diminished to 50 measures; double this pressure, or 4 Ibs., will compress it to 25 measures. On the other hand, if the pressure be diminished, its elasticity will restore it to iU former state. Then, if lb. be applied to the 100 measures, it will ex- pand to 200 measures. Halve this, or 4 of a pound, and the volume will be double, or 400 measures. The same is true of all other gaseous bodies, while they retain their gaseous state. Hence the following law, that The volume of air and of other gaseous fluids is inversely as the pressure applied. Exp. The rlafticitif of the air may be further shown by putting a bladder, half filled with air, under the receiver of an air-pump, and exhausting the air from the receiver; the external pressure being thus taken off, the air within the bladder will expand, fill the bladder, and even burst it. This force is often so great, as to burst the strongest vessels. Hence the danger of forcing too much air into the ball oFan air-gun, or carbonic acid into a soda fountain. Winds. In consequence of the great elasticity and compressibility of the air, it gives rise to the phenomena of winds. It is subject to the laws of elastic fluids in general ; as one portion therefore becomes ex- panded by heat, the colder or more dense portions rush rapidly into its place, and force it to ascend. From the same properties, also, vi- brations are easily produced in it, which give rise to the sensation of sound, musical tones, etc. Pressure of the Air. That the air had weight, was first noticed by Galileo, in 1640. Torricelli, his pupil, carried out Common Air. 161 his suggestions, and in 1643 invented the barometer* by which variations of pressure could be accurately measured. The exact weight of the atmosphere is of great importance in physical-and chemical researches, and has been accurately determined by Dr. Prout. At the level of the sea, its pressure is 15 Ibs. on every square inch of surface. Exp. This pressure may be illustrated by exhausting the air from the receiver of an air-pump ; the pressure on the external surface of the receiver will fix it immovably to the plate. The body of a man sustains constantly a pressure of about 14 tons ! As we ascend above the level of the sea, the mercury sinks in the barometer, because the column of air is shorter ; hence the height of mountains may be measured in a very expeditious manner. Aeronauts in this manner determine the height to which they ascend. t Extent of the Atmosphere. The height of the atmosphere, as estimated by the phenomena of refraction, is found to be about forty-five miles. Above that height, no refraction takes place hi the rays of light. Dr. Wollaston estimates its ex- tent, by the law of the expansion of gases, at forty miles ; that is, the weight of the particles of air (gravity) will over- come their elasticity at that height. Composition of the Atmosphere. Chemists are not agreed whether the atmosphere is a chemical or a mechanical com- pound. The proportions 20 or 21 parts of oxygen and 79 or 80 of nitrogen in 100 never vary, from whatever parts of the earth, or regions of the atmosphere, it may be taken. Gay Lussac brought air from an altitude of 21,735 feet, and its composition did not vary from that on the surface of the earth. Exp. That the atmosphere is composed of 4 parts of nitrogen arid 1 of oxygen, by measure, may be shown by a graduated glass tube of * Torricelli first filled a glass tube three feet in length with mercury, and, on inverting it in a vessel of the same liquid, found that the mer- cury fell about six inches ; hence the atmosphere sustained a column of mercury of about thirty inches. The space abandc.ied by the mercury is called the Torricellian vacuum, and is the most perfect that can be formed. t There seems to be a constant relation between the pressure of the atmosphere and the weather. During a storm, the mercury in the barometer sinks, indicating that the atmosphere is lighter, and rises again when fair weather returns, proving its greater weight. Invalids often complain of the oppressive weight of air in foul weather ; the fact, as we have seen, is the reverse ; they feel a difficulty in respira- tion, because the air is too light. The same difficulty is felt by aero- nauts, and those who ascend high mountains. 14* 162 Nitrogen and Oxygen. known capacity, and bent as in Fig. 75. Putabitof Fig. 75. phosphorus into the bent end, and place the open end in a vessel of water, keeping the finger over the end to prevent the air from escaping. Bring now near the phosphorus a red-hot iron ; the phospho- rus will be inflamed, and will burn out the oxygen of the air ; phosphoric acid will be formed, and absorbed by the water; the latter will rise, and fill the tube l-5th full; the remaining 4-5ths is nitro- gen. This uniformity in the composition of the atmosphere has been regarded as a decisive proof of its chemical constitution. But it has been shown by Dalton, that it is the results of a mechanical, rather than of a chemical law. This law may be illustrated in the following manner : Exp. Take two strong glass tubes closed at one end, and fill the one with oxygen and the other with, hydrogen gas. Close the tube con- taining oxygen with a cork, through the 'centre of which is inserted a small glass tube. Having inverted the tube containing the oxyifn, place upon it that containing the hydrogen, so that one cork shall rl<>s<> both tubes; let thorn remain in an upright position. As the o.\yrt n in the lower vessel is sixteen times as heavy as the hydrogen in the upper, we should expect that eacli would maintain its position; but the fact is otherwise. They mutually intermingle, as is proved by their forming explosive mixtures in both tubes. Similar experiments have been made upon a great number of gases, and it is uniformly found that, after a little time, they will distribute themselves equally through the space occupied by both, whatever be their difference of density ; hence it u ,is inferred by Dalton that different gases are vacuums in rrspcrt to each other; that is, that one gas does not prevent the en- trance of another into the space which it occupies, any more than the vacuum of an air-pump, although it will flow more slowly in the former than in the latter case. All gases and vapors follow the same law ; hence there are as many at- mospheres around the earth as there are gases upon its surface, each occupying the same space which it would oc- cupy if it were entirely alone. This tendency to diffusion renders it difficult to confine gases in bladders, or even over water in the pneumatic cistern. Exp. By placing hydrogen gas in a glass tube, one end of which is stopped by plaster of Paris, over water, the hydrogen will force itself out through this plaster so rapidly as to prevent the entrance of the air, and the water will rise in the tube ; but, as the water rises, the at- mospheric pressure is such as to force the air into the tube, and the water will fall. By igniting the gas, it will explode ; which shows that there has been a mingling of the air with the hydrogen. Protoxide of Nitrogen. 163 Impurities. The air usually contains other gases; car- bonic acid and watery vapor are the most abundant. The quantity of water is determined by the hygrometer. It never amounts to more than one per cent. Carbonic acid rarely exceeds iifov Traces of hydrochloric acid are frequently found in the vicinity of the ocean, and of nitric acid in rain water, produced by lightning. The air ne'ir cities often contains other substanfres, organic matter, sulphuric acid, and ammonia. The odoriferous par- ticles of flowers, and other vegetable and mineral substances, are often detected in it. It was formerly supposed, that the healthy state of the air depended upon the proportion of oxygen in it ; hence the origin of the term ctfr/in/mtry, which was applied to the process of analyzing the air; but, since the oxygen of the air is found to be constant, it is now applied also to the modes of ascertaining its purity. This is effected either by exploding a given portion of air with hydrogen in the (H'l'onutcr, (see page 152,) or by placing in a portion of confined air some substance to abstract the oxygen. Uses of the Air. The utility of the atmosphere in the economy of nature cannot be too highly rated. It is absolutely essential to animal and vegetable life. Its constitution is one of the most beautiful illus- trations of the wisdom and goodness of the Creator. Protoxide of Nitrogen. Symb. NO. Equiv. 14.15 + 8 = 22.15. Sp. gr. 1.5239. 100 cubic inches weigh 47.2536 grains. History. Discovered by Priestley, 1772, and named by him dephlogisticated nitrous air. Davy called it nitrous oxide. Process. This gas may be formed by decomposing nitrate of ammonia. Exp. Put a few grains of this salt into a glass retort, and apply heat. At a temperature of between 400 and 500 Fahr. it liquefies, bubbles of gas begin to appear, and in a short time brisk effervescence. The gas may then be collected in the ordinary way over warm water, and suffered to remain a short time, until the water absorbs the nitrous acid which is often formed with it. Tlicory. The changes which take place may be thus ex- plained : the NH 3 -f-NO 5 , containing 2N, 5O, and 3H, are converted into 3HO, or water, and 2NO. Properties. The protoxide of nitrogen is a colorless, in- odorous gas, of a sweetish taste, and does not affect the vege- table blues ; it is rcot, therefore, an acid or an alkali. 164 Nitrogen and Oxygen. It supports combustion almost as powerfully as oxygen gas. Ezp. A candle is relighted in the same manner as in oxygen gas. Iron wire, charcoal, and most combustibles, burn in it. Phosphorus burns with nearly the same brilliancy as in oxygen gas. Exp. Mix equal volumes of the protoxide and hydrogen gas, and it will form an explosive mixture, which may be exploded in the gas pistol by flame, or the electric spark ; but generally it requires the temperature of the substance to be raised to a higher degree than oxygen, because the heat is necessary to decompose the gas, so that its oxygen may unite with the combustible, and its nitrogen escape into the air. Respiration of this Gas. When respired, it is a powerful stimulant. Its effects upon the animal system were first in- vestigated by Sir H. Davy in 1799. In his experiments on the effects of respiring the various gases, he breathed nine quarts of this gas for three minutes, and twelve quarts for four. No quantity would *tt/>jnn't n ffjirntinn for a longer period. The effects are pleasurable in the highest degree, resembling the first stages of intoxication. The effect varies very much with temperament, but generally gives an unusual propensity to muscular action, a rapid flow of vivid ideas, and the more prominent traits of character are made ttill more prominent. This excitement continues but for a few minutes, and gen- erally is not succeeded by the languor and exhaustion conse- quent upon other stimulants.* Its effects, however, upon some temperaments, have proved decidedly injurious. It is hoped that so powerful a stimulant will be applied to some good use in medicine. Binoxide of Nitrogen. Symb. N + 2O, NO 2 or N. Eq. 14.154-16 = 30.15. Sp. gr. 1.0375. History. Discovered by Dr. Hales ; but its properties were first investigated by Dr. Priestley, in 1772, who gave it the name of nitrous air. Nitric oxide and nitrous gas have also been applied to it. Process. It may be formed by the action of dilute nitric acid (2 parts of water to 1 of acid) upon copper filings, or * It may be administered from a silk or India-rubber bag, furnished with a stop-cock, by repeatedly breathing it from the bag and back again, as long as it will support easy respiration. Nitrous Acid. 165 mercury. Place the materials in a retort, and collect over water. Theory. In this process, the nitric acid is decomposed. 3 equiv. of oxygen unite with the copper, forming the peroxide of copper, and 2 equiv. of oxygen combine with the nitrogen, and form the binoxide ; the peroxide of copper is then united to some undecomposed nitric acid, and forms the nitrate of copper. Cu and !^NO 5 are converted into Cu0 3 -fNO 5 and NO 2 . Properties. This gas is colorless, and slightly absorbed by water. It is perfectly irrespirable, exciting spasms in the glottis, which immediately closes to prevent its passage into the lungs. It extinguishes most burning bodies, although phosphorus and charcoal, introduced in a state of vivid com- bustion, burn with increased brilliancy, owing, doubtless, to its decomposition, which is easily effected by heat or elec- tricity. Binoxide of nitrogen has a strong affinity for oxygen. Exp. Pass oxygen into a jar of it, and red fumes will be formed. This is a test of the gas. Atmospheric air will produce a similar ef- fect ; * hence it may be used to separate the oxygen from the nitrogen of the air. Hyponitrous Acid. Symb. N + 3O, NO 3 or N. Equiv. 14.15-^24 = 38.15. This compound was discovered by Gay Lussac, and is said to be formed when 400 measures of binoxide of nitrogen are mixed with 100 of oxygen, both quite dry. When the resulting orange fumes are exposed to a cold of zero, Fahr., they are condensed into a liquid. Properties. The anhydrous acid is colorless at zero, and green at common temperatures. It is so volatile, that, in open vessels, the green fluid wholly and rapidly passes off in the form of an orange-colored vapor, density of 1.72. In the manufacture of sulphuric acid, it exerts an important agency, by forming with water and sulphuric acid a crystalline com- pound, the production of which seems essential to the process. Nitrous Acid. Symb. N + 4O, NO 4 or N. Eq. 14. 15 -f 32 46.15. History. Known for some time under the name of fuming nitrous acid. Its true nature has been ascertained by Davy, Gay Lussac, and Dulong. * Owing to this property, an attempt has been made to introduce it into cudiometry ; but the results are not perfectly satisfactory. 166 Nitrogen and Oxygen. Processes. 1. It is formed by adding oxygen gas in excess to the binoxide of nitrogen over mercury, and putting a strong solution of potassa into the receiver before mixing the gases ; red fumes appear, and combine with the potassa. 2. It may be obtained in the form of a gas, by exhausting a glass globe of air, and introducing 100 volumes of oxygen to 200 volumes of the binoxide of nitrogen.* 3. The best mode is to expose, in an earthen retort, nitrate of lead, carefully dried, to a red heat, and collect the gas in a tube surrounded by ice. For the purposes of experiment, it may be formed by introducing oxygen, or common air, into a jar of the binoxide, over water; deep orange-red colored fumes appear, which are rapidly absorbed by the water ; or by simply taking up a jar of the binoxide, and exposing it to the air. In each case, nitrous acid is formed, and may be known by its red fumes. Properties. The vapor is of an orange-red color, rapidly absorbed by water. At common temperatures, the liquid is orange-red ; below 32, yellow, and nearly colorless at zero, Fah?. ; density, 1.451 ; anhydrous, exceedingly volatile, pun- gent to the taste, and powerfully corrosive, giving a yellow stain to the skin. It has decided acid properties, t both in the gaseous and liquid states. Exp. Into a long glass tube, filled partly with vegetable infusion, and partly with the binoxide, introduce a frw bubbles of oxygen ; the infusion will immediately turn red, owing to the formation ol nitrous acid, and the absorption of it by the infusion. Respiration of Nitrous Acid. It is highly suffocating and poisonous, exciting great irritation and spasms in the glottis, even when moderately diluted with air. Nitric Acid. Symb. N + 5O, NO 5 or N. Equiv. 14.15 = 54.15. History. This acid was first discovered in distilling a mixture of nitrate of potassa and clay, by Raymond Lully, * If collected over water, it is converted into nitric acid; if over mercury, it is decomposed, and the mercury is oxidized. t Some chemists believe it to be a compound of nitric and hyponi- trous acids, from the fact that, when it is added to an alkaline solution, the products are a nitrate and a hyponilrite of the base. Nitric Acid. 167 Fig. 76. a chemist of the Island of Majorca. Basil Valentine, in the 15th century, describes a process of obtaining it, and calls it the water of nitre. Its composition, however, was first de- termined by Mr. Cavendish, in 1785, by exposing oxygen and nitrogen in a glass tube over mercury, in which some water was present, to the action of the electric battery. It has since been examined by Davy, Dalton, Henry, Berzelius, and Gay Lussac. Process. Gay Lussac ob- tained nitric acid by adding the binoxide of nitrogen slowly to an excess of oxygen over water. By this process, it is found to be composed of 250 volumes of oxygen to 100 of nitrogen. But the usual process for obtaining it, is to heat, in a large tubulated retort, a, (Fig. 76,) a mixture of 3 parts of nitre (nitrate of po- tassa) and 2 of sulphuric acid,* and condensing the gas in the globe receiver 6, by dropping ice-cold water from the tunnel t upon the tube of the retort, or by surrounding the receiver 6 with ice. The liquid, as it is condensed, passes into the bottle C. Impurities. The acid of commerce is not perfectly pure ; three ncids are generated in the process the nitrous, hyponitrous, and nitric. It also contains hydrochloric and sulphuric acids Nitrous., acid gives it a color varying from yellow to orange and green, and may be ex- pelled by heat ; the hydrochloric may be detected and separated by a few drops of the nitrate of silver, with which it will combine and form a white solid. The sulphuric acid is separated by re-distilling it with nitre. Properties. Nitric acid, in its most concentrated state, is a \vhite, or limpid liquid, specific gravity of 1.55, and of a peculiarly nauseous odor. It boils at 248, and freezes at -50 Fahr. * The London College of Physicians employ equal weights of nitrate of potassa and sulphuric acid. The Edinburgh and Dublin Colleges employ 3 of nitre to 2 of acid. According to Thompson, the strongest acid is obtained from 6| parts of sulphuric acid to 12| of nitre; the specific gravity of which is 1.55. 168 Nitric Acid. Chemical Properties. It is one of the most energetic of substances. It acts upon the skin, and gives it a yellow stain ; it is eminently poisonous ; has a very strong affinity for water, and cannot be wholly separated from it, before decomposition takes place. It acts as a supporter of combustion ; in this case, it is decomposed, and the oxygen combines with the combustible. Exp. Pass hydrogen and nitric acid through an ig- Fijr. 77. nited porcelain tube ; a violent detonation will be pro- duced, which is due to the combination of the oxygon of the acid and the hydrogen. Exp. Pour strong nitric acid on dry, powdered char- coal ; the charcoal will be ignited, with the evolution of dense fumes. Exp. Phosphorus takes fire in it, (Fig. 77,) sometimes with violent explosion. Exp. Pour nitric acid on to some of the essential oils, as spirits of turpentine, and they will be iiiH;iin-l. The acid in these experiments should be pour- ed from a wine-glass, attached to the end of a long rod. Nitric acid unites with various metals, such as iron, tin, copper, with great energy, and is decomposed by them. It also suffers decomposition by boiling it in contact with sulphur, or by exposing it to the solar rays. In this case, the color changes to a yellow, and deep orange, in conse- quence of the formation of nitrous acid. The action of the binoxide of nitrogen produces the same effect, as may be shown by passing it through nitric acid. In consequence of its yielding up its oxygen so readily, it is one of the most powerful oxidizing agents. Uses. It is used extensively in chemistry and the arts; for etching on copper, and as a solvent of tin to form a mor- dant for some of the finest dyes; in metallurgy and assaying, to bring the metals to their maximum of oxidation ; in medi- cine, as a tonic. The nitric acid of commerce is J water, and called double aquafortis ; another kind, j water, is called simply aquafortis. Nitrohydrocliloric Acid. This is the aqua regia of the alchemists, and is formed of 1 part of nitric to 4 of hydro- Nitrogen and Chlorine. 169 chloric acid. It possesses the remarkable property of dissolv- ing gold and platinum, but does not form a distinct class of salts. NitroJiydrofluoric Acid. This acid is formed by a mixture of nitric and hydrofluoric, acids, and dissolves metals, which are not dissolved by the preceding acid, and is therefore an important re-agent. Nitrogen and Chlorine. Quadrochhridc of Nitrogen. Symb. N + 4C1 or NCI 4 . Eq. 14.15 + 141.68 = 155.83. Sp. gr. 1.653. Discovered hi 1811 by Dulong, and subsequently examined by Davy and others. Process. This very extraordinary substance may be formed by the union of nitrogen and chlorine in their nascent state, or the chlorine may be obtained in ajar, and inverted over a solution of J part of hy- drochlorate of ammonia to 12 of water; a part of the chlorine unites with the hydrogen of the ammonia, forming hydrochloric acid, and another poition unites with the nitrogen of the ammonia, and forms the quadro-chloride of nitrogen, which appears in the form of yellow, oily drops on the surface of the solution. Properties. A yellow, oily liquid, of an irritating and pe- culiar odor: it retains the liquid state below zero, Fahr. It may be distilled at 160 Fahr., but explodes between 200 and 212, and suffers decomposition. It is- one of the most explo- sive substances yet known. A drop of the size of a pea, brought in contact with phosphorus, or with any of the oils, will explode with great violence. It is dangerous to experi- ment with it, even in so small portions. Dulong lost an eye and a finger, and Davy had both eyes injured by exploding small quantities of it. As it is liable to explode without any assignable cause, great care should be used in its prepa- ration. Nitrogen and Iodine. Teriodide of Nitrogen. Symb. N -f- 31 or NP. Eq. 14.15 + 378.9 392.24. This compound, discovered by M. Cour- tois, is obtained in a similar manner with the preceding. Exp. Put iodine in a solution of ammonia, and there will be precip- itated a blackish powder, which may be thrown, in the course of half an hour, upon a filter, washed and dried. When dry, it explodes by the slightest touch, or even spontaneously. 15 170 Nitrogen and Hydrogen. Nitrogen and Hydrogen. Ammonia. Symb. N-J-3H or NH 8 . Eq. 14.15 + 3 = 17.15. History. This substance was known to the alchemists by the names of hartshorn, volatile alkali, spirit of sal-ammo- niac, etc., but was first noticed as a distinct gas by Dr. Priest- ley, who gave it the name of alkaline air. The name ammo- nia is derived from one of the salts from which it was pro- cured, the hydrochlorate of ammonia, or sal-ammoniac, and this from the temple of Jupiter Ammon, in Lybia, from which place it was first obtained. Process. Mix together equal parts of pulverized Fig. 78. hydrochlorate of ammonia and recently-slacked lime in a common retort, and apply heat. The gas may be collected over mercury, or, in consequence of its being lighter than the air, the materials may be put into a Florence flask, a, (Fig. 78,) to which is at- tached a long glass tube. Invert over it a receiver, r, and the gas will displace the air, and fill the re- ceiver; (for a test of the gas, hydrochloric acid may be used, which produces a white cloud.) It may also be obtained by simply heating the com- mon aqua ammonia of commerce. The liquid ammonia, or aqua ammonia, is prepared by passing the gas through \\ in Woulfe's apparatus, in the same manner as in the prepa- ration of hydrochloric acid. (Seepage 154.) Theory. When lime and the hydrochlorate of ammonia are r.scd, the hydrochloric acid deserts the ammonia, and combines with the lime, leaving the former to escape in the gaseous form. Properties. Ammonia is a colorless gas, of a strong, pun- gent odor ; becomes a transparent liquid under pressure of 6.5 atmospheres, and at a temperature of 50 Fahr. It cannot support respiration in its pure state, but may be inhaled with safety when mixed with the air. It is inflammable, but extinguishes the flame of most burn- ing bodies. Exp. A candle immersed in this gas, burns with increased flame, tinged with yellow before it goes out. When expelled from an orifice Nitrogen and Hydrogen. 171 surrounded by oxygen gas, and ignited, it burns with a pale yellow flame. The products are water and nitrogen. It has a strong affinity for water and for alcohol. Exp. A few drops of water, introduced into a jar of the gas over mercury, will instantly absorb it, and the mercury will rise. Ice pliiced in ajar of it over mercury, is melted rapidly. Alcohol absorbs several volumes of this gas, and the solu- tion has a strong odor, commonly called spirits of hartshorn. The dccojnposition of ammonia is effected by chlorine and iodine. Exp. Place a flask of ammonia over a bottle with a wide mouth, containing chlorine gas. The gases will instantly combine, as will be seen by a sheet of white flame. Theory. The chlorine unites with the hydrogen of the ammonia, forming hydrochloric acid ; and this unites with some undecomposed ammonia, and forms hydrochlorate of ammonia, and will be deposited on the sides of the flask in a solid state. Ammonia, both in the gaseous and liquid form t possesses decided alkaline properties* Exp. Place a jar of ammoniacal gas on a plate containing vegetable infusion, and the infusion will become green. Uses. Ammonia is used in the arts and in medicine. In chemistry, it is employed to neutralize acids. Exp. Colors changed by acids may often be restored by ammonia. Hence clothing spotted by acids, especially woollen clothes, may have the color restored by moistening the spots with the liquid ammonia. In medicine, it is used as a tonic. It is a powerful and * This introduces to us a new class of bodies the alkalies. Am- monia is the only one the base of which is not a metal, and there is still some doubt whether its base, nitrogen, is not a body with a me- tallic base. This view corresponds best with the general analogy of other compounds. The alkalies generally have the following prop- erties : 1. Caustic to the animal organs, corrode woollen cloth, and are gen- erally powerful solvents of animal matter. 2. Volatilized by heat, but, excepting ammonia, are not easily de- composed by it. 3. Combine with acids, and form salts. 4. All soluble in water. 5. Unite with oils, and form soaps. 6. Taste acrid, very different from acids. 7. Change some vegetable blues to green. This last property is a convenient one to distinguish them from acids. One of the best tests of acids and of alkalies, is an infusion of purple cabbage, which is changed to red by acids, and to green by alkalies. 172 Carbon. grateful stimulant, producing the useful effects of alcohol, without its injurious consequences. Ammonia is the sub- stance employed for smelling-bottles.* SECT. 8. CARBON. 3.52 Water =1. 1. OKI- v $ b y vol. 100. .,':> Nitrogen, 75 Hydrogen, 1.75 The gases will be given up again by heating the charcoal, or partially by 'plunging it into water. Theory. Tliis power cannot be, attributed wholly to chemical action, but is due to the porous texture of the charcoal; and the gases appear to be absorbed in the same manner that sponges and other porous bodies absorb liquids. The property is most remarkable in the com- pact varieties, such as that from box- wood, where the pores are numer- ous and small. By reducing it to powder, this power is diminished. In plumbago, and in the diamond, it is wholly wanting. But how does this account for its absorbing more ofone gas than of another ? Chemical affinity has doubtless some influence, but it IB mostly due to the elasticity of the gases. Those gases, easily converted into liquids, are absorbed in greater quantities than those more perma- nent; hence vapors are absorbed more easily than gases, and liquids than ether. Hence, too, charcoal, when exposed to the air, or other gases, increases in weight.* * The increase varies with the kind of wood from which it is made. According to the experiment of Allen and Pepys, charcoal from fir gains 13 per cent. ; lignumvitse, 9.6 per cent. : that from Box, 14. I Oak, 16.5 Birch, 16.3 | Mahogany, . . 18. Properties. 175 The absorption is the most rapid during the first twenty- four hours ; it absorbs oxygen from the air more rapidly than nitrogen. Ii also absorbs the odoriferous and coloring principles from most animal and vegetable substances. I'.rj). Pass ink through pulverized charcoal, and the color will be discharged. Red wines, ruin, and brandy, may be rendered colorless by filtration through it. It is used extensively for refining sugar, rind for preparing colorless crystals of citric acid, and other vegetable produc- tions. Stagnant water, and most animal and vegetable sub- stances, in a putrescent state, will be cleansed and purified by this substance ; hence its use to purify docks, vessels, etc. Putrescent meat is purified by rubbing it with charcoal ; and, generally, all substances subject to putrescence may be preserved for a long time, by surrounding them with charcoal. In consequence of this property, it is used in medicine as nri antiseptic in putrescent diseases. Animal charcoal is the best for these purposes, and as its efficacy depends upon Us power of absorption, it should be heated, to expel all the gas, before it is used, or kept in well-stopped bottles as soon as prepared. It is very combustible. It requires a strong heat to ignite it, but then it will burn for a long time, the oxygen of the air uniting with it and forming carbonic acid.* In conse- quence of this property, it is one of the most useful substances in nature. It is the most durable substance known. Grains of wljeat and rye charred in Herculaneum by the volcanic eruption, A. D. H), were easily distinguished from each other, eighteen centuries afterward ; an arrow head has been charred, and even the form of the feather preserved. The stakes driven down in the bed of the Thames, by the Britons, to prevent the army of Julius Caesar from passing the river, were discovered about fifty years since, and were all charred to a consider- able depth. They were as perfect as when driven ; were made into knife-handles, and sold as antiques at a high price. Farmers char their troughs and posts to prevent decay. * Large quantities of powdered charcoal often ignite spontaneously, owing, doubtless, to the small quantity of potassium which is gener- ally found in connection with it. 176 Carbon. It is infusible. by any degree of heat, except that from a powerful galvanic battery ; and in this case there is reason to doubt whether there is a fusion of any thing but of some im- purities in the carbon. Uses. The uses of carbon have already been stated, and are generally well known. It is orie of those substances which are indispensable to the wants, to the existence of our race ; and the Creator has given us, in its character and abundance, the most decisive proofs of his wisdom and benevolence. Carbon possesses extensive powers of combination, and forms a class of substances of great and permanent utility in chemistry, the arts, and the common business of life. . Carbonic Oxide. Symb.COorC. Equiv. 6.12 + 8= 1 i I -2. Sp.gr. 0.9727, air=l. History. Discovered by Priestley by the distillation of charcoal with the oxide of zinc ; but its composition wa- iir.-t determined by Mr. Cruickshank. Process. The best and most convenient mode of obtain- ing this substance, is to put 2 parts of well-dried chalk, pulverized, to 1 of iron filings, into a gun-barrel, and raise the temperature to a red heat. The gas .may then be col- lected over water ; it may be obtained, also, by heating the oxides of several of the metals with powdered charcoal. Theory. Chalk is composed of carbonic acid and lime. One equiv- alent of oxygen contained in the acid, goes to the iron, and converts the acid to the carbonic oxide ; oxide of iron and lime remain, or CO* -f- CaO and Fe are converted into FeO, CaO, and CO. Properties. A colorless, insipid gas, of an offensive odor. It is highly inflammable, and burns with a pale blue flame when a lighted taper is plunged into it, but does not support combustion. A mixture of 1 part of oxygen to 2 of the gas is explosive ; the result is carbonic acid. It is destruc- tive to animal life ; an animal immersed in it soon dies. When diluted with air, it causes fainting and giddiness. Carbonic Acid. Symb. C +2O, CO 2 or C. Equiv. 6.12 22.12. Sp. gr. 1.5239, air=l. History. Discovered in 1757 by Dr. Black, who called ^ Carbonic Acid. 177 it fixed air* This was the first gas known, except tlie atmosphere, and laid the foundation of pneumatic chemistry. Natural History. Carbonic acid exists very abundantly in nature, generally in combination with lime, forming the carbonate of lime, or marble. Process. It is obtained by the combustion of the diamond in oxygen gas, or by burning charcoal in the air, or oxygen; but it is more easily obtained by decomposing some of the carbonates. Take pulverized carbonate of lime (marble or chalk) in a glass retort, and pour on sulphuric or hydro- chloric acid, diluted with five or six parts of water, and collect over water, or in a globe receiver, in the same man- ner as hypochlorous acid gas.t (See page 133.) Theory. In this process, the sulphuric acid combines with the lime, forming the sulphate of lime, and liberates the carbonic acid. SO 3 , CO 2 -fCaO are converted into SO 3 -fCaO and CO 8 . Properties. It is colorless, inodorous, and elastic, requir- ing a pressure of thirty-six atmospheres, 540 Ibs., to the square inch, to condense it into a liquid more than 1J times as heavy as atmospheric air, and hence may be poured from one vessel to another, like water. It is neither a combustible nor a supporter of combustion. Exp. Into ajar of carbonic acid, let down a pendent candle. It will be extinguished as soon as it reaches the gas, or it may be poured upon the candle from a vessel. The flame does not cease from want of oxy- gen, since four measures of air and one of carbonic acid will extin- guish flame ; hence a positive influence is exerted upon it. It is rapidly absorbed by water. Exp. If a small quantity of water be agitated in a bottle containing carbonic acid gas, it will soon absorb it, and acquire acid properties. Recently-boiled water will absorb one volume of the gas at the com- mon temperature and pressure, but increases in its absorbing power in proportion to the pressure applied. It absorbs twice its volume when the pressure is doubled, three times its volume when the pressure is trebled, etc. * Its composition was first demonstrated synthetically by Lavoisier, who obtained it by the combustion of charcoal in oxygen gas. Smith- son Tennant proved its composition analytically by passing the vapor of phosphorus over chalk, heated to redness in a glass tube. t If intended to be kept long, it should be transferred from the cis- tern in bottles, as the water rapidly absorbs it. 178 Carbon. Water may be acidulated with it, by employing Woulfc's apparatus, in the same manner as wiih hydrochloric acid. (See page 154.) In the common soda fountains, the water is confined in a strong brass or copper vessel, and charged with the gas by a forcing-pump. The pleasant, pungent taste and sparkling appearance of fermented liquors, so.h, and Seidlitz waters, and the waters of many mineral springs, are due to the carbonic acid which they hold in solution. The water saturated with it makes a pleasant and healthful drink. But the gas escapes on exposure to air and heat. Hence all such drinks soon become insipid. If the pressure is removed, the escape of gas is much more rapid. Exp. Place a tumbler of water, (Tip. 79,) satu- rated with this gas, under the receiver a of an air-pump b, and exhaust the air. The gas will escape so rapidly as to present the appearance of boiling. Any of the fermented liquors will produce similar phenomena. If the water saturated with the acid be rapidly congealed, the frozen water has the appearance of snow, its bulk being greatly increased by the immense number of bubbles formed by the liber- ated gas. It is an acid y as shown by chemical tests. Erp. Put a piece of litmus paper into water saturated with it, and it is turned red ; but by heat, or exposure to the air, the color returns, owing to the escape of the acid. This is not the case with any other acid ; the colors they form are generally permanent, unless changed by alkalies. The best test of carbonic acid is lime water t which is ren- dered turbid by the gas. Theory. Carbonic acid unitejs with the lime which the water holds in solution, and forma the carbonate of lime, which is soluble in water, and is precipitated in fine powder. This gives to the water a milky appearance. If, however, you continue to add carbonic acid, it will dissolve the carbonate, and the water will become clear again, carbon- ate of lime being very soluble in excess of carbonic acid. Solidification of Carbonic Acid. It has lately been ascer- Carbonic Acid. 179 tained, that when the gaseous carbonic acid is subjected to a pressure of thirty-six atmospheres, it is condensed into a liquid, and at -85 into a solid resembling compact snow.* Relations to Animal Life. Although water saturated with carbonic acid proves a healthful and invigorating drink, the free acid cannot be taken into the lungs without producing almost instant death ; in fact, the glottis closes at its ap- proach, and will not suffer it to enter. If it be diluted with air, it acts upon the system as a narcotic poison ; an animal thrown into it is usually suffocated. t Carbonic acid is heavier than the air, and hence often remains in wells and deep pits, where it is generated, and called by the miners choki-damp. Before descending, a candle should be let down, and if it will not burn, life cannot ba supported. The acid may be absorbed by pouring down large quantities of water ; it may be partially expelled by exploding gunpow- der near the bottom ; or it may be drawn up with large buckets. Production of Carbonic Acid. Causes are in constant operation to form carbonic acid, and throw it off into the * Mr. Faraday first condensed carbonic acid into a liquid by placing carbonate of ammonia in one end of a strong glass tube, bent twice at right angles, and sulphuric acid in the other end, which is sealed her- metically. When the acid is poured upon the ammonia, it combines with it and liberates the gas, which, by the pressure, is condensed ; but this process is attended with much danger, from the bursting of the tube. A safer method has been contrived by Thillorier, in which tin- gas is condensed in a strong metallic cylinder. By allowing the liquid acid to escape through the stop-cock, it expands so rapidly as to become frozen, owing to the absorption of t its sensible caloric. A re- duction of temperature to -162 is said to have been produced by this means The solid acid thus formed is about the weight of carbonate of magnesia, perfectly white, and of a soft, spongy texture. "It evapo- rates so rapidly that mercury, and even alcohol, (sp. gr. .820,) are frozen. According to the experiments of Mitchell, of Philadelphia, the greatest cold produced by the solid acid in the air was -109, and under an exhausted receiver -136. The pressure at 32 was 36 atmospheres, at 6U, 60 atmospheres, and at 86, 72 atmospheres, or 1290 Ibs. to the square inch. When obtained in a liquid form in a glass tube, it is colorless and extremely fluid In attempting to open the tubes at one end, they uniformly burst into fragments, with violent explosions. t Caution. This gas is always produced in burning charcoal ; and hence the danger and criminality of placing pans of hot coals in sleeping apartments, or in rooms not ventilated by a chimney. The acid gradually mixes with the air, causing drowsiness, and even death, before the person can escape. Every year adds new proofs, in the loss of many lives, to the folly and danger of such practices. 180 Carbon. atmosphere. It is evolved in great quantities from the earth, from ordinary combustion, and by the respiration of animals. In the two last cases, the oxygen of the air is consumed, and carbonic acid takes its place; hence we should expect, if there were nothing to counteract this process, that the whole atmosphere would, in time, be rendered unfit to support respiration ; but not more than T( JQV P art f tne atmosphere is carbonic acid. In places near cities, or where it is evolved from the earth, the proportion may be greater. This ten- dency, however, may be counteracted by the vegetaUe kipg- dom. During the daytime, plants absorb carbonic acid, de- compose it, retain its carbon, and throw off its oxygen. In the night, the process is reversed; oxygen is consumed, and carbonic acid is thrown off; but more of oxygen is emitted in the daytime than is consumed in the night; more carbonic acid also is consumed during the day thun is given off dur- ing the night. The balance from this process is needed to meet the demands of the anima) kingdom, which const; ntlv consumes oxygen, and generates carbonic acid in the pr- of respiration. Thus the equilibrium of the atmosphere is preserved, and both kingdoms flourish together. Ezp. That carbonic acid is given off in renpiration, may be show t, by breathing with a quill through limo \\.it, -r, which will become tur- bid. This tact enables us to understand the process of Respiration. The blood, in its progress through the tem, becomes filled. with carbon, which gives to it a dark color. When it passes into the lungs, the air is brought in contact with it; the carbon unites with the oxygen, fon carbonic acid, which is expelled, and the blood is chan-jrd to a bright red ; it is now fitted to nourish the system. Some suppose that the oxygen enters into the blood, and that the combination takes place during the course of circulation ; but whichever theory be adopted, carbonic acid is thrown off, and oxygen is consumed. Hence, in crowded assemblies, great quantities of this gas are formed, and, as a consequence, dulness and fainting often ensue. Hence, also, the neces- sity of having large public rooms well ventilated. Bichloride of Carbon (Symb. CC1. Equiv. 12.24 -f 35.42 = 47.60) was discovered by M. Julin. It occurs in small, soft, adhesive fibres, of a white color, of a peculiar odor, resembling spermaceti, and is taste- less ; burns with a red flame, emitting much smoke, and fumes of hy- drochloric acid gas. Protochloride of Carbon. Symb. CC1. Equiv. 6.12 -f- 35.42 =41 .54. Jt is obtained by passing the vapor of perchloride of carbon through a Compounds of Carbon. 181 heated glass tube, filled with fragments of rock crystal, to increase the heated surface. It is a limpid, colorless liquid j density, 1 .5526. |- Chloride of Carbon. Symb. C 4 C1 5 . Equiv. 24.48 -f 177.1 = 201.58. Discovered by Liebig, and sometimes called the new chloride of Liebig; obtained by boiling chloral with a solution of lime, potassa, or baryta. It is a limpid, colorless liquid, similar in odor and. appearance to the oily fluid which chlorine forms with olefiant gas ; density, 1.48 : boils at 141 Fahr. Per chloride of Carbon. Symb. C 8 CR 12.24 -f 106.26 = 118.5. Dis- covered by Faraday. When olefiant gas is mixed with chlorine, com- bination takes place between them, and an oil-like liquid is formed, consisting of carbon, hydrogen, and chlorine. Expose this liquid, in a jar of chlorine, to the solar rays, and hydrochloric acid is set free, and the chloiine unites with the carbon. Properties. At common temperatures, it is a colorless, transparent solid, of an aromatic odor, resembling that of camphor ; fuses at 320, and boils at 300. Cliloro-carbonic Add. Symb. O -|- C -f Cl. Equiv. 8 -f- 6.12 -}- 35.42. = 4i>.54. This singular compound of oxygen, chlorine, and carbon, affords a somewhat unusual instance of two acidifying principles uniting with one base to form an acid. It was discovered by Dr. Davy, who called it Phosgene gas. It is formed by exposing equal volumes of chlorine and carbonic oxide to the solar rays, when rapid but silent combustion takes place, and they contract to one half their volume. Properties. A colorless gas, with a strong odor; reddens litmus pa- per, and combines with fou/ times its volume of ammoniacal gas. Wa- ter and* several of the metals decompose it. Chloral (Symb. C 9 C1 6 O 4 . Equiv. 299.60) is a new compound of carbon, oxygen, and chlorine, discovered by Liebig, and prepared by the mutual action of alcohol and chlorine. It is a colorless, transparent liquid, of a penetrating, pungent odor, nearly tasteless, oily to the touch ; density, 1.502, and boils at 201. Pniodide of Carbon was discovered by Serullas, and is obtained by mixing an alcoholic solution of pure potassa and of iodine. It forms crystals of a pearly lustre, sweet to the taste, and of a strong, aromatic odor, resembling saffron. The Protiodide is formed by distilling a mixture of the preceding compound with corrosive sublimate. It is a liquid of a sweet taste, and penetrating, ethereal odor. Bromide of Carbon. Formed by mixing 1 part of periodide of carbon with 2 of bromine : two compounds are formed, the bromide of carbon and the sub-bromide of iodine; the latter is removed by a solution of caustic potassa. It is liquid at common temperatures, but crystallizes at 32 Fahr. ; sweet to the taste, and of a penetrating, ethe- real odor ; distinguished from the protiodide by the vapor which it emits on exposure to heat. 16 182 Carbon and Hydrogen. Carbon and Hydrogen. Two compounds of carbon and hydrogen have been known for some time, but 'of late the number has been increased to at least twelve. Dicarburet of Hydrogen. Symb. C + 2H or CH*. Equiv. 6.12 + 2 = 8.12. Sp. gr. 0.5593, air = 1. History. This substance is generally known under the name of light carbureted hydrogen. The names hrury in- flammable air, the inflammable air of niar. of oxygen, and kindled by flame, or the electric spark, it explodes with great violence. This may be shown by the gas pistol. There is, however, much danger of bursting the pistol; glass vessels should not be employed to explode it. Exp. Bubbles of the mixture may be passed up through the water of the cistern, and exploded upon the surface ; but care should be taken that the fire is not communicated to the vessel containing the mixture, through the bubbles as they rise. It is decomposed by heat. By passing it through a porce- lain tube at a low red heat, charcoal is deposited, and the bicarburet evolved, which, at a white heat, is also decom- posed. It is also resolved into hydrogen and carbon by a succession of electric shocks. Action of Chlorine. When 2 volumes of chlorine and 1 of olefiant gas are mixed and ignited, they burn rapidly, 184 Carbon. Gas Lights. and form hydrochloric acid, while the carbon is deposited but, if the gases remain at rest, they slowly combine, and form an oily liquid, of a yellow color, called chloride of hydro- carbon. Carburet of Hydrogen, EtJurint, (Symb. 4C + 4H. Equiv tCar = 2 Faraday in the process of compressing oil gas into strong copper globes, for the supply of portable gas. It is a highly volatile liquid, the lightest liquid body known. At 00, it is exceedingly combustible, and burns with a brilliant flame. | Carburet of Hydrogen (Symb. 6C-J-3H. Equir. 36.72 + 3 = 39.72. Sp. gr. 0.85) was obtained by Faraday from the same oil gas liquid which yielded etherine. At common temperatures, it is a color- less, transparent liquid, smells like oil gas, with a slight odor of almonds. It is highly combustible, and form* with oxygen a powerful detonating mixture. Parrajfine is a compound of carbon and hydrogen, obtained by the distillation of the petroleum of Rangoon, and also by that of tar de- rived from beech wood. It is a fatty substance, without taste or odor, and burns with a pure white flame. Eupione differs from the preceding compound only in containing a mailer portion of carbon. It is obtained by distillation of the tar derived from bones or horns. It is a tasteless, inodorous liquid, similar to oils, but as limpid as alcohol. Naphtha (Symb. 6C + 5H. Equiv. 36.72+ 5 = 41.72. Sp. gr. 0.753) is obtained from coal tar by distillation. It is a volatile, limpid liquid, of a strong, peculiar odor, and generally of a light yellow color. It is very inflammable, burning with a white name and much smoke. It is used to preserve potassium. Naphthaline (Symb. C'H 4 . Equiv. 61 .2-}- 4 =65.2) is obtained in the same manner as the preceding compound. It is a white, crys- talline solid, heavier than water, has an aromatic pungent taste, ;m voimi air would explode but feebly, and above 14 volumes of air to 1 of gas did not explode at all. It was also found that it re- quired the heat of flame to explode it. Iron at a red heat, and even at a white heat, would not affect it. But the fact which led immediately to the invention of the safity l(nnj), had been observed by Dr. Wollaston, that "an explosive ;///>- ture cannot be kindled through a glass tube so narrate as } of an inch in diameter." It was also noticed that the mixture could not be exploded through fine wire sieves, or gauze wire, which acts on the same principle as longer tubes. * In 1812, an explosion occurred in Felling colliery, in Northumber- land, by which ninety-two men lost their lives. The explosion was heard three or four miles ; thirty-two persons only were saved alive. In 1815, a similar occurrence happened at Durham, and destroyed fifty-seven persons ; and in another, twenty-two lost their lives. Carbon. Safety Lamp. 187 Fig. 8O. Exp. Place the gauze wire a (Fig. 80) over a jet -of the gas; the flame may be pressed down, and will not pass through the wire. Exp. Let a stream of the gas pass through the wire c ; the g;is may be ig- nited on the top of the wire, but will not communicate through it to the tube Fig. 81, b. The same is true of flame,* by whatever substance it is produced. The wires conduct off the heat, so lint they do not gain the temperature requisite to ignite the gas. Safety Lamp. This consists simply of a common lamp, a, (Fig. 81,) with a gauze wire, 6, surrounding the flame. The wire should have at least 625 apertures to the square inch. Furnished with this lamp, the miners can enter the mines in perfect safety from explo- sion, but are exposed to suffocation, when there is not sufficient oxygen in the mines to support the combustion of the oil. To enable the miner to escape from the mine when the atmosphere becomes such as to extinguish the flame of the lamp, a platinum coil may be inserted around the wick. Thus, in the lamp 6, (Fig. 82,) let a platinum coil a be inserted around the wick ; when the flame ceases, the combus- tion will continue slowly for hours, so as to heat the platinum red-hot. This will give sufficient light to enable the miner to escape. This is founded on the fact, that plati- num wire or foil will, if heated, cause certain gases to com- bine gradually, with the production of a red heat, but with- out flame. Exp. Pour a small quantity of ether into the lamp, and, having heated the coil of platinum, plunge it into the ether ; the heat, of the wire will cause the vapor of ether and the oxygen of the air to com * The flames of candles, lamps, gas lights, &c., are hollow, as may be shown by holding a plate of glass over them. Flames formed by a mixture of oxygen with the combustible are solid ; hence the use of the blowpipe, bellows, &c., to render the flame solid and increase the heating power. 188 Carbon and Nitrogen. bine, BO as to keep the wire red-hot, and sometimes even at a white heat, when the ether will burst into a flame Carbon and Nitrogen. Bicarburct of Nitrogen, or Cyanogen. Symb. NC 2 or Cy Equiv. 14.15 + 12.24 = 26.39. Sp. gr. 1.804, air= 1. History. This gas was discovered in 1815, by Gay Lussac. It is sometimes called nituret of carbon, but bicarbunt of nitrogen expresses definitely its composition. Process. It is obtained from the bicyanuret of mercury, by heating the salt in a small glass retort, with a spirit lamp. The retort should be. covered with lute, to prevent its melting. At a red heat, it is decomposed. The cyanogen passes over in the form of a gas, and the mercury is sublimed, and remains in the neck of the retort in small globules. Collect over mercury or air. Properties. This gas is colorless, with a strong, pungent odor; not a supporter of combustion, but burns itself with a beautiful purple flame, resembling the peach blossom Water, at the common temperature and pressure, al>s>r times its volume, and alcohol 25 times its volume. At the tem- perature of 45, and under a pressure of 3.G atmospheres, it is condensed into a limpid liquid, but resumes the ga.~ state when the pressure is removed. The most remark ihlr chemical property of this substance is, that it acts like a simple body in most of its combinations, forming substances consisting of three elementary bodies, analogous to those formed in other cases by two. Cyanic Acid (Symb. Cy + O. Equiv. 26.39 +8 = 34.39) may be obtained by exposing cyanuric acid to a dull red heat. It has a penetrating odor, pungent, and caustic to the skin, producing great irritation of the eyes; very volatile, giving off an inflammable vapor. Fulminic Acid. This is isomeric with the preceding, i. e., identical in composition, but possessed of different properties. It is called fulminic because its compounds of mercury and silver are highly explosive. Cyanuric Acid (Symb. Cy3Q 6 H3. Equiv. 130.17) was obtained by Serullas by gently boiling bichloride of cyanogen Compounds of Carbon. 189 in water: cyanuric and hydrochloric acids are the results. The hydrochloric is removed by evaporation, and the cyan- uric deposited, on cooling, in oblique rhomboidal crystals. The crystals are further purified by solution and evaporation. Paracyanuric Acid is identical in composition with the preceding, but different in properties; it results from the spontaneous decomposition of hydrous cyanic acid. Chloride of Cyanogen. Symb. Cy -f Cl. Eq. 61 .81 . First obtained in a pure stale by Sorullas, in 1829, by exposing bicyanuret of mercury in powder, and moistened with chlorine gas in a well-stopped vial. It congeals at zero in needle-shaped crystals ; is liquid between 5 arid 10, but above this it is a colorless gas, of a very offensive odor, irri- tating to the eyes, corrosive to the akin, and highly injurious to ani- mal life. liichlor'uh of Cyanogen. Symb. Cy-f-2Cl. Eq. 97.23. Discovered also by Serullas, by putting 155 grains of pure hydrocyanic acid into a bottle containing sixty cubic inches of dry chlorine, and exposing it to the solar rays. The acid is vaporized, and, in the course of a few hours, a colorless liquid is formed on the surface of the bottle, gradu- ally growing thicker, until, in the space of twenty-four hours, it sets into a white solid, with shining crystals. This is the bichloride of cyanogen. It is exceedingly poisonous, caustic to the taste, and pene- trating odor, similar to the chloride. Bromide of Cyanogen is similar to the preceding. Hydrocyanic Acid, .or Prussic Acid, (Symb. Cy + H. Equiv. 2 6.39 -(-1=27.39,) was discovered by Scheele, in 1782. Berthollet afterwards ascertained that it was a com- pound of carbon, nitrogen, and hydrogen ; but it was first procured in a pure state by Gay Lussac. Process. The best process is that of Vauquelin. Fill a narrow tube, placed horizontally, with fragments of bicyan- uret of mercury, and then pass a current of dry hydrosul- phuric acid gas very slowly through it. Double decomposi- tion ensues as soon as the gas comes in contact with the bicyanuret, when hydrocyanic acid and bisulphate of mercury are formed. When the bicyanuret becomes black, the acid is expelled by a gentle heat, and collected in a receiver sur- rounded with ice. Properties. It is a limpid, colorless liquid, of a strong, but agreeable odor, similar to that of peach blossoms. It excites, at first, a sensation of coolness on the tongue, which is soon followed by heat; but, when diluted, it has the flavor of bitter almonds; exceedingly volatile; boils at 79, and 190 Sulphur. congeals at zero', unites with alcohol and water in all proportions, but possesses very feeble acid properties. It is a most virulent poison. A single drop, if placed on the tongue of a dog, causes instant death. A girl swallowed a small quantity of it diluted with alcohol, and fell instantlv, as if struck with lightning, and died in two minutes. A professor of Vienna put drops upon his arm, and was deprived of life in a few minutes. But though a most potent poison in its pure state, when much diluted, it has been em- ployed as a medicine, in cases of consumption, with beneficial effects. This, like many other violent poisons, cannot be employed for criminal purposes, without the almost certain risk of being discovered. It Exists in the laurel, peach, and in beef-steak. SECT. 9. SULPHUR. Sulphur has been known from the remotest antiquity. Natural History. It exists in nature, in a pure state, in the vicinity of volcanoes. It collects in the craters, either in fine powder or in crystalline solids; but it exists more abun- dantly in combination with the metals, forming the sulphurets of iron, copper, lead, silver, etc., from which it may be sub- limed by heat, but is not quite pure. It is found also in many mineral waters ; in many minerals, such as gypsum, sulphate of strontia, etc.; in all animals, and some plants. Process. The sulphur of commerce exists in two states ; in rolls, called roll brim ft our t and in fine powder, called flow- ers of fiilp hur ; but the two varieties are readily resolved into each other by the application of heat. Exp. Heat a brick, or small iron cup, to nearly a red heat. Place upon it roll brimstone, and invert over it a bell-glass receiver ; the sulphur will sublime* i.e., pass into a fine po\ydt-r, like vapor, and col- * This may serve to illustrate the process of svUim&tion as applied to other substances. Camphor and gum benzoin are easily sublimed. The process of converting mercury into vapor, and condensing it, is also called sublimation, .although it is a liquid. Sulphur. Properties. 191 lect on the sides of the vessel. In this way the flowers of sulphur are prepared. Properties. Sulphur is a brittle solid, of a lemon-yellow color, nearly tasteless, and inodorous, except when rubbed or heated. It is a non-conductor of electricity, but becomes neg- atively electrified by friction ; fuses at 216 Fahr. ; possesses the highest degree of fluidity between 230 and 280, and is of an amber color; at 320, it begins to thicken, acquiring a red tint ; between 423 and 4S2, it is so tenacious as to re- main in the vessel when inverted ; but, from 482 to its boiling point, it grows fluid again, and sublimes rapidly from 550 to 630 Fahr. When cooled from the several temperatures above named, it possesses different dtgrees of consistency. Cooled suddenly from the most fluid state, it is hard and brittle; but if plunged into cold water between the temperatures of 320 and 482, it is soft, and may be drawn out like wax; cooled from the boiling point, it is of a deep red-brown color, very soft and transparent. It is prepared in this way for taking seals. The native crystals are octohedrons, with rhombic bases; those formed artificially occur in oblique rhombic prisms. Exp. Melt a few pounds of sulphur in an earthrii crucible,* (Fig. 63,) and, when it is partially cooled, pierce the crust so thai the fluid parts may flow out; on breaking the mass when cooled, the interior will'exhibit a cluster of beautiful crystals. Fig. 81 rep- resents a section of the crucible containing the sulphur after it has cooled. Sulphur is soluble in boiling oil of turpentine, which is a test of its puri- ty. Sulphur is highly combustible ; it burns with a pale blue flame, and com- bines readily with the metals. Exp. Mix copper or iron filings with sulphur, and heat them in a glass tube, or crucible, by a spirit lamp. The sulphur will combine, and form sulphurets of these metals. Impurities. Sulphur contains some hydrogen in its purest * There are four principal varieties of crucibles : 1. Wedgwood cru- cibles are made of a mixture of burned and unburned clay ; 2. Black 192 Sulphur. Sulphurous Acid. state; but the more common ingredients are earthy sub- stances and arsenic ; the latter is tested by ammonia. Uses. Employed extensively in the manufacture of gun- powder, for seals, medallions, and as a cement for iron. Used in medicine, for the diseases of the skin, humors, etc. The milk of sulphur, which is sulphur combined with water, and precipitated from some of its alkaline solutions by an acid, occurs in a gray powder, and is sometimes used in medicine. Hyposulplmrous Acid. Symb. 2S + 2O. Eq. 32.2+ 16= 48.2. It is difficult to procure this in a pure state. It may be formed by digesting sulphur in a solution of any sulphitr. It is distinguished by uniting with the oxide of silver, which separates the acid from soda. Sulphurous Acid. Symb. S + 2O or SO 8 . Eq. 16.1 -f 16 = 32.1. Sp. gr. 2.2117, air=l. History. Sulphurous acid appears to have been known from an early period. Stahl first pointed it out as a distinct substance; but its discovery in a pure state was made by Priestley, in 1774, and accurately analyzed since, by Gay Lussac and Berzelius. It exists in nature in the vicinity of volcanoes, and issues from the fissures in the craters, and from the lava, often in immense quantities. Process. Burn sulphur 'in common ;iir, or in dry oxygen gas, over mercury; but the best method is to put 2 parts of mercury and 3 of sulphuric acid into a retort, and apply the heat of a lamp, and collect over mercury. . Theory. The sulphuric acid has 3 equiv. of oxygon, one of which unites with the mercury, forming the oxide of mercury, which com- bines with some undecomposed sulphuric acid, and forms the sul- Icad crucibles are formed by a mixture Fig. 84 of clay and plumbago ; 3. Hessian crucibles are composed of a mixture of sand and clay ; 4. Metallic cruel- lies are made of silver, platina, &c. These latter are used with the spirit lamp in analytical processes. The form of these vessels is represented in Fig. 84. Metallic and porcelain crucibles are generally provided with covers and stands, as in the figure, but the best stand is a piece of fire- brick. Sulphurous Acid. 193 phate of mercury, which remains in the retort, and the sulphurous acid comes over in the gaseous state. The gas is heavier than the air, and can be collected in a manner described on page 139, fig. 64. Properties. A transparent, colorless gas, sour to the taste, and pungent, suffocating odor, by which it is distin- guished from all other gases ; extinguishes burning bodies, but is not combustible. Exp. A candle immersed in a jar of this gas is instantly extin- guished. It is irrcspirable, and fatal to animal life. When largely diluted with air, it excites coughing, and uneasiness about the chest ; when perfectly pure, it excites spasms of the glot- tis, which prevent its introduction into the lungs ; of course, an animal confined in it is instantly suffocated. It reddens vegetable colors, and then discharges them. Exp. Place a rose over an ignited sulphur match in the open air, and it will turn white ; hence it is used for bleaching straw, silk, arid for removing fruit-stains from woollen cloths, etc. It has a strong attraction for water and oxygen. Water absorbs it so rapidly, that, if ajar of the gas be inverted over it, the atmosphere will force the water into the jar with great violence ; recently-boiled water absorbs 33 times its volume. Sulphurous acid will remain with dry oxygen without change, but if water be present, it combines with oxygen, and forms sulphuric acid. It instantly decomposes those oxides, the metals of which have a weak affinity for oxygen, such as those of gold, platinum, and mercury. Nitric acid yields to it one proportion of oxygen, and converts it to sul- phuric acid. Liquid Sulphurous Acid. It becomes liquid by the pres- sure of two atmospheres, and even by surrounding it with a freezing mixture. In this state it is anhydrous, a little heavier than water, (sp. gr. 1.45,) and boils at 14 Fahr. By its evaporation, it produces so intense a degree of cold, that mercury may be frozen, and several of the gases rendered liquid. Exp. Pour liquid sulphurous acid upon water contained in a shal- 17 194 Sulphur. low vessel ; the acid will boil, and its vapor will absorb so much caloric that the water will soon be frozen. Exp. Or pour it upon mercury in a shallow dish, and place it under the exhausted receiver of an air-pump ; the mercury itself will soon congeal. It may be obtained in the solid form in crystals containing water, by passing the moist gas through a receiver, cooled from 50 to 14 Fahr. Uses. Sulphurous acid is often employed for bleaching purposes, for whitening straw and silks, and for the barbarous purpose of killing bees. Ilyposulphuric Acid. Symb. 2S -f- 5O. Equiv. 32.2 -f- 40 = 72.2. This acid was discovered in 1819, by Welter and Gay Lussac. Process. It may be formed by passing sulphurous arid gas through water containing peroxide of m By the interchange of elements, th: 1 sulphate of the peroxide and the hyposulphate of the protoxide of manganese are formal ; the latter remains in solution. The manganese is thrown down by pure baryta, and the hyposulphate of baryta ob- tained, which crystallizes by evaporation, and is then decom- posed by sulphuric acid, by which the sulphate of baryta is precipitated, and hyposulphuric acid remains in solution. Properties. Colorless, inodorous, sour to the taste, red- dens litmus, and cannot be wholly freed from water. Sulphuric Acid. Symb. S + 3O, SO 3 , or S. Equiv. HI. I -f-24 = 40.1. Sulphuric acid was discovered by Basil Valentine, near the close of the fifteenth century. It is commonly called oil of vitriol, because it was first obtained by the distillation of green vitriol, (sulphate of iron or cop- peras.) It exists in nature abundantly in the sulphate of lime, (gypsum.) Process. Anhydrous sulphuric acid may be obtained from the hydrous acid, manufactured at Nordhausen, in Germany, from the protosulphate of iron, and called fuming sulphuric, acid. But the best method is that of Professor Mosander, of Stockholm. Saturate the oxide of antimony with excess of sulphuric acid, and then, by a slow heat, drive off the excess Sulphurous Acid. 195 of acid, when the salt will crystallize as a dry sulphate of antimony. Expose this salt to a dull red heat in a retort, and the anhydrous acid will be driven off, and may be collected in a dry receiver, surrounded with ice. Properties. In this state, the acid has some peculiar prop- erties. It is a white, opaque solid ; fuses at 66 Fahr. ; sp. gr. 1.99; boils between 104 and 122, forming a transparent vapor ; has a powerful affinity for water, so that, on exposing it to the air, it flies off in white fumes. Hydrous Sulphuric Acid, which is the ordinary acid of commerce, may be obtained by several modes. Exp. Burn a mixture of 8 parts of sulphur to 1 of nitre in a vessel of oxygen gas containing a vegetable infusion; the acid will be ab- sorbed by the water, and change the infusion red. But the process for manufacturing this acid in the arts, is done in chambers lined with sheet lead* 8 parts of sul- phur to 1 of nitre, coarsely bruised and mixed together, are put upon iron plates, 1 Ib. to 300 cubic feet of air. The mixture is ignited by a hot iron, and the door closed. Water, to the depth of 6 inches, covers the floor, and absorbs the acid as fast as formed. The room is then ventilated, and the process repeated every four hours, until the water is suffi- ciently acid ; or, by an improvement in the structure of the room, the sulphur is burned in a separate room, and the air, admitted continually, carries the acid vapor into the chamber, where it is condensed by the water. This acidulated water is then drawn off and concentrated by heat, in leaden boilers, until it is of the specific gravity '1.450, and the concentration is finished in glass or platinum dishes placed in sand baths. Theory. By the combustion two gases are formed sulphurous acid from the sulphur, and binoxide of nitrogen from the nitre. The latter combines with the oxygen of the air, and is converted into the nitrous acid. The sulphurous and nitrous acids then combine with the watery vapor, and form a crystalline solid, composed of sulphuric acid, hyponi- trous acid, and water. When this solid drops into the water, it is instantly decomposed, the sulphuric acid is retained in the water, and nitrous acid and binoxide of nitrogen escape. The nitrous acid thus set free, as well as that formed by the binoxide and oxygen of the air, again combines with the moist sulphurous acid, and forms the solid, vhich sinks to the water, and is decomposed again. This process con- * The usual size of the chamber is 20 feet long, and 12 wide ; but in one establishment in England, the chamber is iJiO feet by 40/ and 20 high, containing 96,000 cubic feet. 196 Sulphur. tinues, until the whole is converted into sulphuric acid, and absorbed by the water. Properties. Hydrous sulphuric acid, when pure, is an oily, limpid liquid, colorless, inodorous, intensely sour and corrosive ; destroys, by the aid of heat, all animal and vege- table bodies, with the deposition of charcoal, and formation of water ; hence the acid often attains a brown tinge by charring substances which accidentally fall into it ; boils at 620 Fahr., and freezes at -15. When its specific gravity is 1.78, it congeals above 32, and remains solid up to 45; but when mixed with twice its weight of water, it congeals at -36. It has a powerful affinity for water. It combines with the water of the air, even at boiling temperatures, so power- fully that its greatest concentration can be effected only by glass or platinum retorts with narrow mouths. Exp. 4 parts of sulphuric acid and 1 of water, each at 50, when poured together, have a temperature of 300. The heat is occasioned by the diminution of bulk, by which the insensible caloric becomes free. Exp. 2 parts of acid and 3 of snow form a mixture which will freeze water, and the thermometer will sink even to -23. The cold results from its affinity for water ; it dissolves the snow to obtain it ; and the heat necessary to render the water liquid is absorbed from the acid and the snow, and passes into an insensible state. Exp. \ part of snow to 3 of acid will produce a heating mixture, because the condensation develops more heat than is required to HH It the snow. The decomposition of sulphuric acid is effected by heat, and by the non-metallic, combustibles. Exp. Pass hydrogen gas and sulphuric acid through a red-hot por celaiu tube. Exp. Heat this acid with charcoal, or put into it vegetable sub- stances. Exp. Expose the acid to the galvanic battery; the sulphur will appear at the negative, and tho oxygen at the positive pole. Its spe- cific gravity never exceeds 1.850. Its strength is tested by its specific gravity, and by the quantity required to saturate a given portion of an alkali. 100 grains of the carbonate of soda will neutralize 9*2 of pure sulphuric acid. It may be detected in any solution by the chloride of barium, by which a white, insoluble solid is precipitated the sulphate of baryta. Sulphur and Hydrogen. . 197 It is one of the most powerful of acids, reddens the vege- table infusions, unites with bases, and forms salts, which are called sulphates. It is a most violent poison. The best antidote is dry mag- nesia. If water be taken, it will produce a very great heat, and thus increase its injurious effects. Uses.- It is one of the principal acids of chemistry and of the arts, in which greater quantities are employed than of any other acid ; for the formation of most of the other acids ; for the preparation of soda from salt, of alurn from .sulphate of iron ; for obtaining chlorine and other gases ; for dissolving indigo for dyes. It is used in medicine as a tonic. Dichlori.de of Sulphur (Symb. 2S-J-C1. Eq. 67.62. Sp. gr. 1.687) was discovered by Dr. Thompson, in Ib04. Prepared by passing a current of chlorine gas over flowers of sulphur, gently heated, till nearly all the sulphur disappears. The dichloride is then obtained by distillation in the form of a reddish liquid. Iodide of Sulphur. Firs* described by Gay Lussac. Formed by heating 4 parts of iodine with 1 of sulphur. A dark-colored substance, easily decomposed by heat. Bromide of Sulphur is obtained by pouring bromine on sublimed sulphur. The product is an oily liquid, of a reddish tint; odor resem- bles the dichloride of sulphur. I Sulphur and Hydrogen. Hydrosulphuric Acid. Symb. SH. Equiv. 16.1 + 1 = 17.1. Equiv. vol. 100. Sp. gr. 1.1782, air = l. This sub- stance was discovered by Scheele, in 1777, and has been variously named, sulphureted hydrogen and hydrotliionic acid. Process. It may be obtained from the sulphurets of the metals. The one generally employed is the protosulphurct of iron, which is a native product, but can be prepared by heating 2 parts of iron filings with 1 of sulphur to a red heat, in a covered crucible ; upon this, in a retort, pour dilute sulphuric acid, apply gentle heat, and collect over water. Sesquisulpkuret vf antimony, treated in the same manner with hydrochloric acid, will yield a purer gas ; the former contains a little iron and hydrogen. Theory. The oxygen of the water unites with the iron, and its hydrogen with the sulphur, and the sulphuric acid unites with the oxide of iron ; the products are hydrosulphuric acid and sulphate of 17* 198 Sulphur and Hydrogen. the protoxide of iron. FeS, SO 3 and HO are converted into SO 3 -f FeO, and SH. Properties. It is a colorless gas, but has an excess! a /// offensive taste and odor ; it is this gas which gives the odor to putrescent eggs, sewers, and the waters of sulphurous springs. It extinguishes burning bodies, but burns with a pale blue flame ; forms an explosive mixture with oxygen, and is so destructive to animal life that y-^ v part of this gas in air destroys small birds ; ^ part killed a middle-sized dog, and ,j- a part a horse. If placed on the cutaneous surface of animals, it will prove fatal to them. Reddens lit- mus feebly, but unites with bases and forms salts. Water absorbs 3 volumes of the gas, and forms a colorless liquid, similar to the gas in taste and odor. This water is a test of the. metals. Nitric acid will cause a precipitate of sulphur ; and if poured into a bottle of the gas, a blue flame will pervade the vessel, and sulphur and nitrous acid fumes be produced. If exposed to the air, it deposits, its sulphur on the surface of the vessel ; but it is readily decomposed by metals in solution ; the sulphur combines with the metal, and the hydrogen is liberated. It is also decomposed by chlorine and iodine, because of their great affinity for hydrogen. Hence chloride of lime is used to purify places rendered noxious by this gas. It is partially decomposed by heat, in a porcelain tube. Liquid Hydrosulphurir, Add. Mr. Faraday succeeded in condensing the gas. Under a pressure of 17 atmospheres, it is colorless, limpid, and excessively fluid ; compared with it, ether appears tenacious and oily. On breaking a tube under water, it rushed out violently, and assumed the gaseous state. Test. The best test of this gas is carbonate of lead. 1 part of the gas mixed with 20,000 of air will give a brown stain to a surface whitened with the lead. Hence persons who use preparations of lead to improve their beauty, on coming into the vicinity of this gas, often change their color. Exp. Write on paper with any of the salts of lead in solution, and pass a stream of the gas over it; the writing will instantly appear. Uses. In medicine for cutaneous eruptions, in the labora- tory as a test of metals ; hence its use in analytical processes. Sulphur and Carbon. 199 Production of Sulphur in Volcanoes by the Meeting of Sul- phurous and Hydrosulphuric Acids. These acids are gener- ated in volcanoes, and, as they meet, are decomposed, and sulphur is deposited. This may be shown in the following manner : Let two small retorts a, a, (Fig. 85,) pass into a globe receiver, 6, so that their mouths shall nearly touch each other. Put the materials for sul- phurous acid into one, and for hydrosulphuric acid in the other, and apply heat; as the two gases meet in the receiver, they will be decomposed, and the sulphur will be deposited upon the interior surface, in fine powder. Ht/drosulphurous Add. Symb. 2S -|- H. Equiv. 33.2. Discovered by Schcele, who called it su/>er.*ufphureled hydrogen. The names Injdrotluunous acid, per or bisnlphureted hydrogen, and persulphuret of hydrofeHfh&VG also been applied to it. It is similar in taste and odor to hydrosulphuric acid, but not so powerful ; semi-fluid, inflammable, and easily decomposed by heat into sulphur and hydrosulphuric acid. .r','--" Sulphur and Carbon. Bisulphurct of Carbon, or Alcohol of Sulphur, Carbosul- phuric Acid. Discovered accidentally by Professor Lampa- dius, in 177G ; but its true nature w^is first pointed out by Clement and Desormes. Process. It is obtained by heating, in a close vessel, the native bisulphuret of iron (iron pyrites} with one fifth of its weight of dry charcoal. " The compound, as it is formed, should be conducted, by means of a glass tube, into a vessel of cold water, at the bottom of which it is collected. To free it from moisture and adhering sulphur, it should be distilled at a low temperature, in contact with chloride of calci- um." T. Properties. A transparent, colorless liquid, remarkable for its high refractive power, acid, pungent, and somewhat aromatic taste, and fetid odor; specific gravity, 1.272, ex- ceedingly volatile; boils at 110; very inflammable,, and burns with a pale blue flame. With oxygen, its vapor forms an explosive mixture ; with binoxide of nitrogen, it forms a 200 Cyanogen and Sulphur. mixture which burns with dazzling brilliancy ; dissolves in alcohol and ether, and is precipitated by water; dissolves phosphorus, sulphur, and iodine, giving to a solution of the latter a beautiful pink color. It is decomposed by chlorine. Cyanogen and Sulphur. Sulphurtt of Cyanogen was discovered in 1828, by M. Lassaigne, by the action of bit- van u ret of mercury, in fine powder, upon half its weight of bichloride of sulphur, confined in a small glass globe, and exposed for two or three weeks to daylight. A small quantity of rrvs- tals, biting to the tongue, and of a penetrating odor, collected in the up- per part of the vessel, which form red-colored compounds with per salts of iron. Bimdpkurtt of Cyanogen (Sy mb. 2S -f Cy) was discovered by Liebig, by exposing fused sulphocyanuret of potassium to a current of dry chlo- rine gas ; it forms a dry, yellow powder. Hydrosulphocyanic Jcid. Syrab. S*CyH. Equiv. 50.59. Dis- covered in 1808, by Mr. Porritt, who ascertained it to be a comp>nnw$, light, and ru< two or three inches long, cut into strips. Then pour ^ ]\ a strong solution of carbonate of potassa, filling the retnrt quite full. Place the beak of the retort in the cistern, and apply heat.* The gas will soon form and inflame when it comes in contact with the air, forming beautiful wreaths of snmkc, which rise up from the water. Or it may be collected like any other gas. Properties. This gas is colorless, and has a highly-olTcn- sive odor, and bitter taste ; will neither support flame nor respiration. Fig. 87. o Inflames spontaneously when admitted into air, and explo- sively with oxygen gas. As the bubbles of the gas (Fig. 87) rise through the water in the cistern b into the air, they inflame successively, the phosphoric acid and vapor form a series of rings, as c, of dense white smoke, continually * The readiest mode of obtaining this gas is to heat phosphorus in connection with quicklime, forming the phosphuret of lime. Drop this into water acidulated with hydrochloric acid. The water is de- composed, and its hydrogen and oxygen unite with the phosphorus, and form hypophosphorous acid, phosphoric acid, and phosphuret of hydrogen. Boron. 207 increasing in size as they arise, and producing one of the most striking and beautiful appearances in experimental chemistry. If a bubble of the gas is admitted into a receiver of oxygen gas, a bright flash of light is seen, and the receiver is jarred by the concussion. This is one of the most re- markable properties of this gas, and distinguishes it from all other gases. It is often produced by the decomposition of bones, in swamps and graveyards, and gives rise to those lights which are frequently seen about such places. It is the real " Jack o' the lantern," or " Will o' the wisp." Water absorbs one eighth volume of this gas, and, if the gas is suffered to remain over water for a few days, it loses its spontaneous inflammability, but will inflame on the applica- tion of a lighted taper. Phosphorus and Sulphur. Sulphurct of Phosphorus. The nature of this compound is not accurately settled ; it is formed by bringing sulphur in contact with fused phosphorus. They act on each other with great violence, producing a compound of a reddish- brown color, which fuses at 16 Fahr., and is highly combus- tible. SECT. 11. BORON. Symb. B. Eq. 10.9. Equiv. vol. 100. This substance was discovered in 1807, by Sir H. Davy, by exposing boracic acid to a powerful galvanic battery ; but its properties were first investigated by Gay Lussac arid The- nard, who obtained it in greater quantity by heating boracic acid with potassium. The easiest method of obtaining it is to decompose boro- ftuoride of potassium, by means of potassium and heat. Properties. A dark olive-colored solid, without taste or odor ; a non-conductor of electricity ; sp. gr. nearly 2 ; insolu- ble in water, alcohol, ether, and oils ; does not decompose water at any temperature, and may be subjected to intense heat in close vessels without change ; heated to 600 in the air, it ignites, and is converted into boracic acid. When 208 Boron and Oxygen. heated with nitric acid, or with any substance which yields oxygen freely, it passes into boracic acid. Boron and Oxygen. Boracic Acid. Symb. B-J-3O. Equiv. 34.9. Sp. gr. 1.479, water 1. This substance exists in. nature in small quantities in the Lipari Islands, and the hot springs of Lasso, in the Florentine territory ; in combination with soda, in the well-known substance borax, the biborate of soda, us-d by smiths as a flux. It is also a constituent of the minerals boracitc and datholite. Process. To a solution of purified borax in boiling water, add half its weight of sulphuric acid, diluted with an equal quantity of water. On evaporation* and cooling, shining crystals of boracic acid will be deposited ; it may be purified by repeated solution in hot water and crystallization. This is a hydrate, containing 1 eq. of acid and 3 of water. The anhydrous acid may be obtained by heating this in a plati- num crucible. Properties. The hydrous acid exists in the form of thin white scales, without odor, and nearly tasteless, sparingly soluble in water, which reddens vegetable blue colors, and, like the alkalies, turns turmeric paper brown, soluble in boil- ing alcohol, and gives a beautiful green color to flame. The anhydrous acid is a hard, colorless, transparent ghss absorbs water rapidly from the air, and should be kept in well-stopped vials ; exceedingly fusible, and communicates this property to the substances with which it unites. Hence its use in the arts as a flux. Fig. 88. * Fig. 88 represents the form of evaporating Hi.-itnf ; some are made of clay and sand, oth- ers of porcelain, glass, silver, platinum, and gold. The substance to be evaporated is poured into thorn, and they are placed in a sand bath, which is simply a quantity of com- mon sand contained in an iron vessel, and connected generally with the furnace or fire- place, so as to be kept constantly at a tem- perature below the boiling point. Selenium. 209 Boron and Chlorine. Terchloride of Boron. Symb. B-f 3C1. Eq. 117.16. Pro- duced by the spontaneous combustion of boron in chlorine gas. It is rapidly absorbed by water, and unites with am- monia, forming a volatile fluid. It is also formed, according to Despretz, by passing dry chlorine gas over charcoal and boracic acid, ignited in a porjcelain tube. It was first noticed by Davy, and examined by Berzelius, Dumas, and Despretz. Boron and Fluorine. Fluoboric Add. Symb. B.+ 3F. Equiv. 66.94. Sp.gr. 2.36:22. Discovered by Gay Lussac and Thenard, in 1810. Process. Mix 1 part of pure boracic acid and 2 of fluor- spar with 12 of sulphuric acid, in a glass flask, and apply heat ; or heat a strong solution of hydrofluoric and boracic acids in a metallic retort. Properties. A colorless gas, of a penetrating, pungent odor ; extinguishes flame, reddens litmus powerfully, and unites with bases forming salts called fluoborates. It has a powerful affinity for water, which absorbs 700 volumes of the gas; becomes hot, fuming, and caustic; attacks animal and vegetable substances with great energy. Some doubt yet exists concerning its true nature. Boron and Sulphur. Sulphuret of Boron is formed, according to Berzelius, by burning boron in the vapor of sulphur. The product is a white, opaque mass, readily decomposed by water. SECT. 12. SELENIUM. Symb. Se. Equiv. 39.6. Sp. gr. 4.32. Selenium was discovered by Berzelius, in 1818, and named Selenium, from Selene, the moon, because he at first mistook it for tellurium. Natural History. It is found in small quantities among 18* 210 Selenium. the volcanic products of the Lipari Islands, in Clausthal in the Hartz, combined with lead, cobalt, silver, mercury, and copper. fierzelius obtained it from the iron pyrites of Fahlun. Process. Mix the native sulphuret of selenium with 8 times its weight of peroxide of manganese, and expose it to a low red heat in a glass retort, the beak of which dips into water. The manganese yields its oxygen to the sulphur, and the selenium sublimes pure, or in the form of seleiimus acid. Properties. A brittle, opaque solid, without taste or odor ; its lustre is metallic, resembling lead in the mass, but the powder has a deep red color ; softens at 212, and may be Davy . . 1807. Strontium . 1 Calcium . J Cadmium . Stromeyer .... 1818. Lithium Arfwedson .... 1818. Zirconium Berzelius .; -"x -/ > . 1824. Aluminium } Glucinium > Wohler 1828. Yttrium ) Thorium Berzelius 1829. Magnesium Bussy . . . . . 1829. Vanadium Sefstrom .... 1830. Latanium . Mosander .... 1839. It will be found convenient, in studying the properties of the metals, to arrange them in groups. They may be divided, for this purpose, into the two following orders : Order I. Metals which, by oxidation, yield alkalies or earths. Order II. Metals, the oxides of which are neither alka- lies nor earths. 19 218 Metals. Potassium. ORDER I. includes twelve metals, which may be arranged in three sections or divisions : Section I. Metallic bases of the alkalies. These are, Potassium, Sodium, Lithium. Section 2. Metallic bases of the alkaline earths. These are, Barium, Strontium, Calcium, Magnesium. Section 3. Metallic bases of the earths. These are. Aluminium, Yttrium, Zirconium. Glucinium, Thorium, ORDER II. The metals belonging to this order are ar- ranged in the three following sections : Section 1. Metals which decompose water at a red heat : Manganese, Cadmium, Cobalt, Iron, Tin, Nickel. Zinc, Section 2. Metals which do not decompose water at any temperature, and the oxides of which are not reduced to the metallic state by the sole action of heat : Arsenic, Columbium, Titanium, Chromium, Antimony, Tellurium, Vanadium, Uranium, Copper, Molybdenum, Cerium, Lead. Tungsten, Bismuth, Section 3. Metals, the oxides of which are decomposed by a red heat : Mercury, Platinum, Osmium, Silver, Palladium, Indium. Gold, Rhodium, T. SECT. 1. METALLIC BASES OF THE ALKALIES. POTASSIUM. Symb. K. Equiv. 39.15. Sp. gr. 0.865. History. The discovery of potassium, or kalium, as it was at first called, was made by Davy, in 1807, and consti- tutes an era in the history of chemical philosophy, as it led Properties of Potassium. 219 to the discovery of the metallic bases of the other alkalies and alkaline earths, and to the decomposition of a variety of compounds which were before regarded as simple bodies. The discovery was made by subjecting the hydrate of potassa to the influence of a powerful galvanic battery of 290 pair of plates; oxygen appeared at the positive, and a small globule of a metallic lustre at the negative pole, which proved to be the metal potassium. Process. Potassium is obtained in small quantities by galvanism ; but the best method is that of M. Curaudau, which was improved by Brunner, and modified by Wohler. The substance employed is carbonate of potassa, prepared by heating cream of tartar to redness in a covered crucible. This is raised to a high temperature, in connection with charcoal, in an iron retort ; the oxygen of the potassa com- bines with the carbon, and the potassium distils over. Properties. Potassium, at common temperatures, is a soft, malleable solid, yielding to the pressure of the fingers, like wax ; of a decidedly metallic lustre ; similar tb mercury in color ; somewhat fluid at 70, and perfectly liquid at 150 ; cooled to 32, it is brittle; sublimes at a low red heat in close vessels secluded from the air ; a good conductor of electricity and of caloric. Ptut its most remarkable property is its affinity for oxygen. It oxiclizes rapidly in the air or oxygen gas; but if a piece be thrown upon water, it will decompose it rapidly, disengaging so much heat that the potassium takes fire, and burns with a beautiful purple fame. The evolution of hydrogen gas causes it to move about upon the surface of the water, and, combining with the potassium, augments the brilliancy of the combustion. Exp. Invert a wine-glass filled with water in the cistern, and in- troduce a small piece of potassium ; it will rapidly decompose the water, and the escape of hydrogen gas will displace the water in the glass. This gas may then be ignited. Exp. Heat a small piece of iron, and drop upon it potassium; then invert over it a jar of oxygen gas. Exp. Drop a piece upon ice, and it will instantly inflame ; a deep hole is made in the ice, containing pure potassa. Exp. To show that the action of potassium upon water produces an 220 Metals. Compounds of Potassium. alkali, drop a small piece into a bottle containing vegetable infusion, and it will instantly turn it grr.cn. In consequence of its affinity for oxygen, it must be kept under naphtha, or the essential oil of copaiba. Remark. In the description of the metallic compounds, the abbreviations symb. and equiv. will be omitted, and the symbols and equivalents placed immediately after the naim-j of the substances. Compounds of Potassium. Protoxide of Potassium, (K + O. 47.15,) commonly called potash, or potassa, is always formed when potassium is put into water, or burned in oxygen gas. It exists in nature in the minerals, feldspar, mica, and several others ; in all \ tables, from which it is obtained by leaching their ashes, and boiling the lye. Properties. The pure potassa is a white solid, very caus- tic, possessing powerful alkaline properties ; easily fused by heat, but not decomposed ; deliquesces in the air, and hence is very soluble in water, forming with it a hydrate, which retains the water under the most intense heat. The Hydrate of Potassa contains 1 eq. of water, and is similar in its properties to the anhydrous potassa. The aqueous solution of the hydrate, called aqua potastrr, inny be prepared by decomposing the carbonate with lime. Exp. Put quick lime, with half its weight of carbonate of p- dissolved in 8 or 10 times its weight of water, into a ch'.ui inui v ss. I, and put it into well-stopped bottles, to exclude the air, from which it will absorb carbonic acid. If the solution is pure, it will not effervesce with acids. The solid hydrate may be made from'this by evaporation, and further purification by alcohol, which dissolves only the pure hydrate ; the alcohol is then driven off by heat. This was formerly" called Inpis causticus, but the colleges of Edinburgh and London called it potassa. fusa. Tests. Potassa may be distinguished from all other sub- stances by the precipitates thrown down from its salts in solution. Exp. 1. Take any of the salts of potassa in solution, and pour into them tartaric acid ; a white precipitate will be thrown down the bi- tartrate of potassa. Compounds of Potassium. 221 Exp. 2. Chloride of platinum will give a yellow, and when dissolved in alcohol, n pale yelloic, precipitate. Exp. 3. Alcoholic solution of carbazotic acid throws dowrt yellow crystals of carbazotate of potassa. This is the most delicate test. Uses. Potassa being a very powerful alkali, is of great use in chemistry and the arts. It forms the bases of most soaps; the crude potash is employed for making glass. Owing to its affinity for carbonic acid, it is used for ab- stracting that substance from gaseous mixtures, and for depriving them of moisture. T.rofidv of Potassium (K + 3O. 63.15) is formed when potassium is burned in the air or oxygen gas. It is an ormge-colored substance, caustic, alkaline, heavier than pot issium, and decomposed by galvanism and by water ; by the Litter it is resolved into the protoxide and oxygen ; fuses below a red heat, in which state it burns vividly, in contact with combustibles. Chloride of Potassium (K -j- Cl. 74.57) was long known by the ri.inus ' febrifuge salt of Sylvius,' * regenerated sea-salt.' It may be formed by the spontaneous combustion of potassium in chlorine, or by dissolving potassium in hydrochloric acid, and evapo- rating the solution slowly to dryness. Properties. It occurs in cubic crystals, colorless, of a salifif. and bitter taste, insoluble in alcohol, and soluble in 3 parts of water at 60, and in less at 212 Fahr. . / >dide of Potassium (K-f-I- 165.45) is formed by heating potassium with iodine, or by heating the iodate of potassa. Properties. Fuses readily, and is converted into vapor below a red heat ; deliquesces in air ; very soluble HI water ; dissolves in strong alcohol, and, by evaporating the solution, yields colorless cubic crystals of iodide of potassium. Bromide of Potassium, (K-f-Br. 117.55,) formed by a process similar to that for the iodide, (using bromine instead of iodine,) and has similar properties; very soluble in water, which, by evaporation, yields anhydrous cubic crystals; easily fused, and decrepitates, like sea-salt, when heated. Exp. Put a small piece of potassium into a wine-glass containing a few drops of bromine ; the two bodies will combine with explosive violence. Fluoride of Potassium (K + F. 57.83) is formed by 19* 222 Metals. Compounds of Potassium merely saturating hydrofluoric acid with carbonate of potassa, evaporating to dryness, and igniting to expel excess of acid. Properties. It has a sharp, saline taste, alkaline to the test papers, soluble in water, and the solution acts on glass. It is obtained from its solution, by evaporation at 100, in cubes or rectangular four-sidrd pritmf, nry (/i/if/m.tut. Hydurct of Potassium. Discovered by Gay Lussac aud Thenard, and may be formed by heating potassium in hydro- gen gas. It is a gray solid, readily decomposed by heat or water. Gaseous hyduret of potassium is produced when hydrate of potassa is decomposed by iron, at a white hr.it. It is a colorless gas, and burns spontaneously in air or oxy- gen gas, but loses its inflammability by standing over mercury. Niturrt of Potassium consists, according to Thenard, of 100 parts of potassium to Il.TiteJ of nitrogen, and is formed by lu-atin^ potassium with amtnoniacal gas. Sulphurtts of Potassium. These are five in number, de- pendent on the quantity of sulphur. The Protosulphuret of Potassium (K-f S. 55.25) is prepared by irning potassium and sulphur in the air, or by decomposing tl, phate of potassa by charcoal or hydrogen gas at a red heat. :>!,.v ! with powdered charcoal, it kindles spontaneously. The Bisulphuret of Potassium (K-J-2S. 71.35) is formed by re- posing a saturated alcoholic solution of hydrosulphate of sulplmn I of potassium, until a pellicle begins to form, and then evaporating to dryness. The Terrulphvret of Potassium (K + S. 87.45) is formed by hmiitur carbonate of potassa to low redness, with half its weight of sulphur, known by the name of liver of sulphur. The Qutnlrosulphurct of Potassivm (K-J-4S. 103.55) is prepared \v transmitting the vapor of bisulphuret of carbon over sulphate of potassa at a red heat, until carbonic acid gas ceases to be disengaged. The Quintosulphuret of Potassium (K-f-5S. 11?U>5) is formed by fusing carbonate of potassa with its own weight of sulphur. The properties of the four last compounds are similar ; they are deliquescent, have a sulphureous odor, and are soluble in water. A solution of the last dissolves sulphur, and renders it probable that other compounds may be formed. Phosphurcts of Potassium. Several compounds exist, but their composition is unknown. Obtained by burning potas- sium in phosphureted hydrogen. Sehniuret of Potassium. Formed by fusing potassium and selenium together. They combine with explosive violence, Sodium. 223 and a crystalline, fusible compound results, of an iron-gray color, and metallic lustre. Cyanurct of potassium (K-{-Cy. 65.54) is formed by heating to red- ness the anhydrous ferric ijanuret of potassium in an iron bottle. Properties. Easily fused, and crystallizes in colorless cubes ; pungent and alkaline to the taste, and poisonous, act- ing like the hydrocyanic acid ; deliquescent, and very solu- ble in water; used sometimes as a medicine. Sulplwcyanurct 'if Potassium K -(- Cy. 97.74. SODIUM. Symb. Na. Equiv. 23.3. Sp. gr. 0.972. Sodium was discovered by Sir H. Davy, in 1807, a few days after the discovery of potassium, and by a similar process. Process. It may be obtained in small quantities by gal- vanism. But the process of obtaining it from soda, now generally practised, is precisely the same as that for potas- sium. Properties. Sodium resembles potassium in many of its properties. It is a white, opaque solid, of a metallic lustre, resembling silver : yields readily to the pressure of the fingers, and may be formed readily into leaves ; fuses at 200 Falir., and is vaporized at a red heat. Sodium has so strong an affinity for oxygen that it rapidly decomposes water to obtain it, but does not inflame unless the water is heated, in which case it throws out beautiful scintillations, often with violent combustion. Exp. Thrown upon water, it moves about upon its surface, having the appearance of a silver ball, gradually growing less till the whole disappears. Exp. Drop a piece of sodium into a test-tube partly filled with warm water; it will soon burst into a flame, and often explode with violence. It oxidizes in the air or oxygen gas, but not so rapidly as potassium ; hence, like that metal, it must be kept under naphtha. The product of its combustion in oxygen, and its action upon water, is soda, the alkaline properties of which may be tested by dropping a small piece of the metal into a bottle containing a vegetable infusion. 224 Metals. Compounds of Sodium Compounds of Sodium. Protoxide of Sodium, (NaO. 31.3,) commonly called soda, and by the Germans natron, is formed by the oxidation of sodium in air or water. Properties. A gray solid, similar to potassa, which it resembles in most of its properties ; very caustic, and has powerful alkaline properties. The hydrate has I eq. of water, and is easily fused. In other respects, it is similar to the anhydrous soda; absorbs carbonic acid from the air, and passes into carbonate. It is distinguished from other alkaline bases by yield inn, with sulphuric acid, the well-known substance called (j/tm- ber's salts. All its salt* are soluble in water, and are riot precipitated by any re-agent, and give a rich color to the blowpipe flame. The soda of commerce is generally a car- bonate prepared from the ashes of marine plants, in the same manner as potash is from land plants. Uses. Employed for the manufacture of hard son ps, ;m;l for culinary and medical purposes. Sesquioride of Sodium (2Na-f-3O. 70.6) is formed when sodium is heated to redness, in excess of oxygen gas. It h < an orange color, but no arid or alkaline properties. It is resolved by water into soda and oxygen. Chloride of Sodium. Na + CJ. 58.72. This substance is formed by burning sodium in chlorine gas, or by saturating soda with hydrochloric acid, and evaporating to dryness. It is a very abundant natural product, under the name of rork salt. It exists in sea-water and salt-springs, from which it is obtained by evaporation. Great quantities are manufac- tured on the sea-coast of New England, and at Salina, N. Y. The water at the latter place, according to the analysis of Beck, contains one seventh of its weight of pure dry chloride of sodium. Properties. A well-known solid, crystallizing in regular cubes, and by sudden evaporation, in hollow, quadrangular pyramids. It is dissolved in 2J times its weight of water, at Compounds of Sodium. 225 69 Fahr. ; gradually fuses when heated, and decrepitates when thrown into the fire ; is decomposed by carbonate of potassa and nitric acid. The different kinds of salt, such, as stored, fishery, bay, &c., arise from its different forms, and not from a difference of chemical constitution. It contains small quantities of sulphate of magnesia and lime, and chlo- ride of magnesium. Uses. The utility of salt depends on its property of pre- serving animal and vegetable substances from putrescence. Iodide of Sodium, (Na-f-1- 149.0,) prepared in the same manner as the iodide of potassium, exists in sea-water, salt-springs, and in the residual liquor from kelp. Bromide of Sodium, (Na-f-Br. 101.7,) analogous to sea-salt, exists in sea-water and salt-springs, and crystallizes in cubes. Fluoride of Sodium (Na-f-F. 41.98) is formed by neutralizing hydro- fluoric acid with soda ; crystallizes in cubes, and when carbonate of soda is present, in octohedrons. Nearly insoluble in alcohol ; soluble in twenty-five times its weight of water ; attacks glass vessels when evaporated in them a property which is common to most of the com- pounds of fluorine. Sulphure/. of Sodium (Na-f-S. 39.4) is obtained in the same manner as the protosulphuret of potassa, and has similar properties. The Cijanuret of Sodium (Na-f-Cy. 49.69) and the Sulphocyanuret of Sodium (Na-f-CyS 2 . 81.89) are similar to the corresponding com- pounds of potassium. Chloride of Soda is prepared by passing a current of chlo- rine gas into a cold solution of caustic soda. This liquor has received the name of Lab arr aqua' s Disinfecting Soda Liquid, and is used extensively in the arts, and in med- icine. Properties. A liquid of a pale yellow color, with slight odor of chlorine. Its taste is sharp, saline, and but little alkaline; reddens turmeric, and then bleaches it. When evaporated, it yields damp crystals ; decomposed by exposure to the air. Uses. It may be used for all the purposes of bleaching to which chlorine was formerly applied, in medicine to purify apartments, dissecting-rooms, for destroying the fetor of ulcers, and for removing the offensive odors of-sewers, drains, and all kinds of animal putrescence. Alloy of Sodium arid Potassium. 10 parts of potassium, 226 Metals. Lithium. and 1 of sodium, form an ayoy.which is liquid at zero, Fahr., and is lighter than naphtha, or rectified petroleum. LITHIUM. Symb. L. Equiv. 6.44. This substance was obtained by Davy, by means of gal- vanism, as a white-colored metal, like sodium ; but it oxidized so rapidly that he was unable to examine its properties. Compounds of Lithium. Protoxide of Lithium, Lit/tin, (L-J-O. 14.44,) was dis- covered, in 1818, by M. Arfwedson, in the mineral petalite; it exists in spotlumene, lepidolite, and several varieties of mica. Process. One part of petalite jo two of fluor-spar are finely pulverized, and the mixture heated with four times its weight of sulphuric acid, till the acid vapors are **.* Properties. Pungent and acrid to the taste. The n tals do not change in moist air ; but in a very dry air, ;. they lose their water of crystallization, and are rendered anhydrous at a full red heat ; decomposed by sulphuric acid and alkaline carbonates. Iodide of Barium (Ba-f-I- 195) is formed by acting; on baryta with hydriodic acid, and evaporating the solution. Soluble in water, and forms colorless, needle-shaped crystals. Bromide of litirinm (Ba-f-Br. 147.1) is prepared by boiling protobromide of iron with moist carbonate of baryta, evaporating the filtered solution, and healing the residue to redness. The product crystallizes, by careful evaporation, in white rhombic prisms, which have a bitter taste, are slightly deliquescent, and soluble in water and alcohol. T. Fluoride of Barium (Ba + F. 87.38) is prepared by digesting moist carbonate of baryta in hydrofluoric acid. It is a white powder, soluble in nitric and hydrochloric acids. Sulphurct of Barium (Ba + S. 84.8) is prepared by pass- ing dry hydrosulphuric acid over pure baryta, at a red heat. It dissolves readily in hot water, and deposits colorless crystals on cooling. It may be employed for obtaining pure baryta by a process described by Turner, 5th ed. p. 308. Strontium, Cyanurct of Barium (Ba-j-Cy. 95.09) is procured by the action of hydrocyanic acid on baryta. It is slightly soluble in water, has an alkaline reaction, and is decomposed by the carbonic acid of the air. Sulphocyanuret of Barium (Ba + CyS 2 . 127.29) is ob- tained in the same way as the sulphocyanuret of potassium. It is very soluble in water, and crystallizes in beautiful needles, slightly deliquescent. Phosphuret of Barium is formed by heating to redness anhydrous caustic baryta, and throwing into it pieces of phosphorus. It decora- poses water, and forms phosphuret of hydrogen. STRONTIUM. Symb. Sr. Equiv. 43.8. Strontium was discovered by a process similar to that for barium, which it resembles in most of its properties ; oxi- dizes in the air ; decomposes water, by which process it is converted into strontia. Compounds of Strontium. Protoxide of Strontium (Sr-{-O. 51.8) was discovered by Dr. Hope, in 1792 ; also by Klaproth. Process. It was formerly extracted from strontianite, (a carbonate of strontia,) found at Strontian, in Scotland ; hence its name. It may be prepared from the nitrate or carbonate of strontia, in the same manner as baryta. Properties. It resembles baryta in most of its properties. A gray substance, pungent and acrid to the taste ; slacked with water, it produces intense heat, and is converted into a hydrate which fuses readily, but the highest temperature of- a blast furnace will not separate the water; soluble in boil- ing water, and crystallizes on cooling. The solution, like baryta, is an excellent test of carbonic acid. Peroxide of Strontium (Sr-|-2O. 59.8) is prepared in the same way as the peroxide of barium, and, like it, is em- ployed to form binoxide of hydrogen ; decomposed by dilute acids into strontia and oxygen. It is white, of a brilliant lustre, inodorous, and nearly tasteless. Chloride of Strontium (Sr-|-Cl. 79.22) is obtained in a manner precisely similar to the chloride of barium; crys- 20 230 Mttals. Calcium \ tallizes from its solutions in colorless prismatic cry which are distinguished from baryta by being soluble in twice their weight of water at 60, and by the red. tinge whirh it gives to the flame of an alcoholic solution. The anhydrous chloride fuses at a red heat, and yields a white, crystalline, brittle mass on cooling. T. Iodide of Strontium (Sr-}-I. 1 70. H is prepared in the same manner as iodide of barium. It is very soluble in water, fuses without decom- position in close vessels, but is resolved into iodine and strontia, by a red heat, in the open air. Fluoride of Strontium (Sr-f-F. 02.48) is obtained in the same way as the fluoride of barium. It is a white powder, sparingly soluble. Protosulphuret of Strontium *(Sr -f- S. 59.9) is similar in its pnj>rr- ties, and modes of preparation, to the corresponding compound of barium CALCIUM. Symb. Ca. Equiv. 20.5. Calcium was discovered by Davy, in 1808, by expo lime to the action of the galvanic battery. Properties. It is of a whiter color than barium, and is converted into lime by oxidation. Its other properties arc unknown. Compounds of Calcium. Protoxide of Calcium (Ca -j- O. 28.5) is generally obtained by burning common limestone (carbonate of lime) in kilns, for three or four days, to expel the carbonic aci.2) is formed by passing the vapor of phosphorus over quick lime, at a low red heat. It is a brown sub- stance, and, when thrown into water, form*, by mutual decomposition, phosphureted hydrogen, hypophosphorons acid, and phosphoric mid. Chloride of Lime. Ca + O+ Cl. 63.92. This substance, commonly called oiymur'mtt' of limr, or bit aching powdn. i> prepared by exposing recently-slacked lime to an atmosphere of chlorine. The gas is rapidly absorbed, and enters into direct combination with the lime, although Dr. Ure thinks that no definite compound is formed. Properties. A dry, white powder, similar to quick lime, having the odor of chlorine, which it readily yields up when moistened with water; possesses powerful bleaching proper- ties, for which purpose it is extensively used in the arts. The strength of the chloride is estimated by the quantity of indigo which a given portion of the bleaching solution will deprive of its color. Used also in medicine, as a disinfecting agent ; it should be kept in every family. MAGNESIUM. Syrnb. Mg. Equiv. 12.7. Magjiesium was discovered and obtained in small quantities by Sir H. Davy, by means of galvanism ; but M. Bussy, in 1830, obtained it in greater abundance by the action of po- tassium on chloride of magnesium. Process. For this purpose, five or six pieces of potassium, of the size of peas, were introduced into a glass tube, the sealed extremity of which was bent into the form of a retort, and upon the potassium were laid fragments of chloride of magnesium; the latter being then heated to near its point of fusion, a lamp was applied to the potassium, and its vapor transmitted through the mass of the heated chloride. Vivid incandescence immediately took place; and, on putting the mass, after cooling, into water, the chloride of potassium, with undecomposed chloride of magnesium, was dissolved, and metallic magnesium subsided. T. Compounds of Magnesium. 233 Properties. A very malleable solid, of a white color, like silver, and of a brilliant, metallic lustre. Dry, air and water do not oxidize it, but moist air does; heated to redness in oxygen gas, it burns vividly, and forms magnesia. In chlo- rine gas it inflames spontaneously. Compounds of Magnesium. Protoxide of Magnesium, (Mg-J-O. 20.7,) commonly known by the name of magnesia, is prepared by exposing the car- bonate to a strong heat, to expel the carbonic acid. Properties. A white, fusible powder, of an earthy appear- ance, without taste or odor; sp. gr. 2.3; very infusible, and sparingly soluble in water, requiring 5142 times its weight at (i9, and 36,000 of boiling water to dissolve it. The prod- uct is a hydrate. It changes vegetable infusions slightly, but possesses the properties of an alkali, by forming neutral salts with acids; absorbs water and carbonic acid from the air, and should be kept in close bottles. It exists in nature in serpentine, steatite, jnagnesite, and in sea-water, in con- siderable abundance. Chloride of Magnesium (Mg-f-Cl. 48.12) is prepared by dissolving magnesia in hydrochloric acid, evaporating to dry- ness, mixing the resrdue with its .own weight of hydrochlorate of ammonia, and projecting the mixture, in successive portions, into a platinum crucible, at a red heat. The ammonia is expelled, and the chloride remains a transparent, colorless mass ; very deliquescent, and soluble in water and alcohol. Iodide of Magnesium (Mg-f-I. 139) is formed by dissolving magnesia in hydriodic acid ; known only in solution with water. Bromide of Magnesium (Mg-f-Br. 91.1) is prepared by dissolving magnesia in hydrobromic acid. It occurs in small acicular crystals, of a sharp taste, very deliquescent and soluble ; it is decomposed by a strong heat. Fluoride of Magnesium (Mg -f- F. 31 .38) is formed by digesting mag- nesia in excess of hydrofluoric acid ; it is insoluble, and bears a red heat without decomposition. 20* 234 Metals. Aluminium. SECT. 3. METALLIC BASES OP THE EARTHS. ALUMIXWM. Symb. Al. Equiv. 13.7. Sir H. Davy proved that alumina was an oxidized body, and Wohler succeeded in decomposing it, from which he ob- tained the pure metal, aluminium. Process. This metal may be obtained by heating the chloride of aluminium with potassium in a covered platinum or porcelain crucible. Intense heat is evolved during the process. After cooling the mass, it is put into water, by which the saline matter is dissolved ; hydrogen gas, of an offensive odor, is evolved, and a gray powder subsides. This powder, after being washed in cold water, is pure (iliiininiuni, * Properties. Aluminium, as thus prepared, is a gray powder, similar to platinum, but when rubbed in a mortar, exhibits distinctly a metallic lustre. Fuses at a higher temperature than cast iron, and in this state is a conductor of electricity, but a non-conductor when cold. Ezp. Heated in the air to redness, it burns brilliantly, and f<>rms alumina ; but when introduced into oxygen gas, at a rod heat, it burns with siHJh splendor, that the eye can hardly support the light, and with so much heat, that the resulting alumina is partially fused into yrlloxv fragments, as hard as corundum, which not only scratch, but lutely cut glass. Exp, Takes fire in chlorine gas at a red heat, but is not oxidizrd hy water at common temperatures, nor attacked by cold sulphuric .-m-l nitric acids ; soluble in solutions of potassa and ammonia, and in hot sulphuric, or dilute sulphuric and hydrochloric acids. Compounds of Aluminium. Sesquioxide of Aluminium (2A1 -f- 3O. 27.4 + 24 = 51.4) is the only known oxide of aluminium, and is commonly called alumina, or aluminous earth. Natural History. Alumina is very abundant in nature, being found in every region of the globe, and in rocks of all ages ; hence it is one of the principal ingredients in most soils. The different kinds of clay of which bricks, pipes, and earthen-ware are made, consist mostly of hydrate of alumina. Compounds of Aluminium. 235 It is also found beautifully crystallized, in some of the most beautiful gems. The ruby and the sapphire are nearly pure alumina. Process. It may be prepared for chemical purposes from alum, which is a sulphate of alumina and pot ass a. Dissolve pure alum in water, and precipitate the alumina by carbonate of ammonia. THis, when washed in hot water and filtered, is the hydrate, which may be rendered pure by a white heat. An easier process is to expose the sulphate of alumina and ammonia to a strong heat, so as to expel the ammonia and sulphuric acid. M. Gaudin has succeeded in forming rubies, by mixing ammoniacal alum with -j^^ part of chromate of potassa, and exposing to a high heat. Properties. Inodorous, tasteless, and possesses the proper- tics both of an acid and an alkali ; insoluble in water, but has a powerful affinity for it ; when moistened, it forms a ductile mass, which gives it its great utility in the arts. It is a re- markable exception to the law, that heat expands all bodies. There are probably several hydrates of alumina. Uses. Used for bricks, and various kinds of pottery. ScsquicMoridc of Aluminium (2A1 + 3C1. 133.66) was dis- covered by Wohler, by transmitting dry chlorine gas over a mixture of alumina and charcoal, heated to redness. It is of a p:ile, greenish-yellow color, partially translucent, of a highly crystalline, lamellated texture, somewhat like talc, but with- out regular crystals. On exposure to the air, it fumes slightly, emitting an odor, like hydrochloric acid gas. Exp. When thrown into water, it is speedily dissolved with a hiss- ing noise, and so much heat is evolved, that the water, if in small quantities, is brought into a state of brisk ebullition, and forms the hytlrochl orate of alumina,. Scsquisulphuret of. Aluminium (2A1-J-3S. 75.7) is prepared by drop- ing a piece of sulphur on to aluminium, strongly heated. It is a vitri- fied, semi-metallic substance, of a dark color. Scsquiphosphuret of Aluminium (2Al-f-3P. 74.5) is formed by heat- ing aluminium in contact with the vapor of phosphorus ; it is a black- ish-gray, pulverulent mass, which, by friction, acquires a dark gray metallic lustre, and, in the air, has the odor of phosphureted hy- drogen. Sesquiseleniuret of Aluminium (2Al-{-3Se. 146.2) is obtained by heating to redness a mixture of selenium and aluminium. It is a black, pulverulent substance, which acquires a metallic lustre when rubbed. 236 Metals. Glucinium Yttrium. GLUCINIUM. Syrab. G. Equiv. 26.5. Sp. gr. 3. Glucinium was obtained by Wohler, in 1828, by the action of potassium upon the chloride of glucinium. The process is similar to that for obtaining aluminium. It appears in the form of a gray powder, which acquires the metallic lustre by burnishing, and is easily oxidized. Sesquioxide of Glucinium, or Glucina, (2G-{-3O. .77,) was discovered by Vauquelin, in 1798. It is found only in the minerals emerald, brryl, and cuclase. Process. It is obtained by exposing beryl in fine powder, with three times its weight of carbonate of potassa, to a strong red heat. The fused mass is dissolved in dilute hydrochloric acid, evaporated to dryness, re-dissolved in acidulated water. and the alumina and glucina are thrown down by ammonia , the precipitate macerated oy carbonate of ammonia, which dissolves the glucina, and on boiling the filtered liquor, car- bonate of glucina subsides; the carbonic aci'd is then expelled by a red heat. Properties. A white powder, without taste or odor, quite insoluble in water. Pure potassa or soda precipitates it from its salts; distinguished from alumina by being prrripit;itrI from its solution with carbonate of ammonia, when the solu- tion is boiled. YTTRIUM. Symb. Y. Equiv. 32.2. Yttrium was prepared by Wohler, in 1828, by a process similar to that for obtaining glucinium. Properties. It has a scaly texture, a grayish-black color, and a perfectly metallic lustre. It is a brittle metal, and burns with splendor in common air, and with still greater brilliancy in oxygen gas. The result of this combustion is the earth yttria, which was discovered in 1794, by Gadolin, in a mineral at Ytterby, Sweden. It is of a white color, soluble in sulphuric acid, and combines with sulphur, sele- nium, and phosphorus. Its salts have a sweetish taste, and some of them have an amethystine color. Thorium Zirconium. 237 THORIUM. Symb. Th. Equiv. 59.6. This metal was procured by the action of potassium on the chloride of thorium ; decomposition being accompanied by a slight detonation. On washing the mass, thorium is left, in the form of a heavy, metallic powder, of a deep leaden-gray color ; and, when pressed in an agate mortar, it acquires metallic lustre and an iron-gray tint. T. Properties. Thorium is not easily oxidized at common temperatures, but burns with great brilliancy in the air. It is not acted upon by alkalies, scarcely at all by nitric, and slowly by sulphuric acid; but is readily dissolved by hydro- chloric acid, with the disengagement of hydrogen gas. Protoxide of Thorium, or Thorina, (ThO. 67.6,) was dis- covered by Berzelius, in 1828, in a rare mineral from Nor- way, called thorite. It is a white, earthy substance, soluble in none of the acids, except the sulphuric, and is precipitated from its solutions by the caustic alkalies as a hydrate, in which state it absorbs carbonic acid from the atmosphere, and dissolves in acids. It is distinguished from alumina and glucina, by its insolu- bility in pure potassa, and from yttria, by forming with sul- phate of potassa a double salt, insoluble in a cold, saturated solution of sulphate of potassa. ZIRCONIUM. Syrab. Zr. Equiv. 33.7. t Zirconium was discovered by Berzelius, in 1824. Process. It is obtained by heating the double fluoride of zirconia and potassa, carefully dried and mixed with potassium, in a glass or iron retort. The mass is then washed in hot water, and digested for some time in hydrochloric acid. Properties. This substance exists in the form of a black powder. It may be pressed out into thin, shining scales, but its particles adhere very slightly. It is a non-conductor of electricity. It takes fire, when heated in the open air, at a temperature below a red heat ; the product is zirconia. Scsquioxide of Zirconium, or Zirconia, (2Zr-j-3O. 91.4,) was dis- covered by Klaproth, in 1789, from the Zircon, or Jargon, of Ceylon. Metals. Manganese. 17 parts of this substance, finely pulverized, and mixed with 21 of litharge, may be fused, arid a glass obtained, soluble in acids, from which the zirconia is derived ; or it can be formed directly by the com- bustion of the metal in oxygen or common air. Properties. A fine, white powder, inodorous and taste- less ; sp. gr. 4 ; exposed to a strong heat, it fuses, assuming a light gray color ; when cool, it is so hard as to strike fin* with steel, and to scratch quartz crystal. ORDER II. METALS^THE OXIDES OF WHICH ARE NEITHER ALKALIES NOR EARTHS. SECT. 1. Metals which decompose Water at a red Heat. MjUrGJVVESE. Symb. Mn. Eq. 27.7. Sp. gr. 8.013. History. In 1774, Scheele described the black oxide of manganese as " a peculiar earth." Gahn 'subsequently dis- covered that it contained a new metal, to which he gave the name of magnesium, a term applied aflerwards to the met. -ill i<- base of magnesia ; and for which the words mangancsium and mangamum have been substituted. The metal is not found in the native or tin combined state, but its oxides are very abundant. Process. Make a paste with finely-pulverized oxide of manganese and oil, and expose it to the heat of a smith's foFge, in a Hessian crucible, lined with charcoal, for the space of two hours. Properties. A hard, brittle metal, of a grayish-rwhite color, and granular texture; very infusible; not attracted by the mag- net, except when it contains iron ; soon tarnishes on exposure to the air, and absorbs oxygen rapidly when heated to redness. Decomposes water slowly at common temperatures, but rapidly at a red heat. Compounds of Manganese. Protoiidt of Manganese (Mn + O. 35.7) may be formed, as shown by Berthier, by exposing the peroxide, sesquioxirle, or red oxide of manganese, to the combined agency of char- Compounds of Manganese. 239 coal, and a white heat; or by exposing either of the oxides, contained in a glass tube, to a current of hydrogen gas, at an elevated temperature. Properties. When pure, it is of a light green, or moun- tain-green color, undergoing little if any change in the open air, but oxidizes rapidly at 600 Fahr., and is instantly converted into the red oxide, at a low red heat, and some- times takes fire. It is the salifiable base of the metal, and is contained in all its salts; hence its strong affinity for acids. Sesquioxide of Manganese (2Mn -f-3O, or Mn-f-liO. 79.4) occurs nearly pure in nature, and may be formed by exposing the peroxide to a red heat. It is the chief residue of the usual process of obtaining oxygen gas, but it is difficult to regulate the heat so a,s to obtain it in a pure state. Properties. The color is brown or black, according to the source from which it is obtained ; unites with nitric and sulphuric acids, and is converted, by exposure to the air, into the peroxide. Peroxide of Manganese. Mn-|-2O. 43.7. This is a well- known native product, commonly called black oxide of man- ganese. Properties. It occurs generally in masses, of an earthy appearance, and black color, mixed with other substances; but it is frequently found in small prismatic crystals. It is not affected by exposure to the air or water, but yields oxy- gen when heated to redness, and is the substance most generally employed for that purpose, (see page 130 ;) does not unite with acids or alkalies. Uses. Employed in the arts for coloring glass, in prepar- ing chlorine gas, and in forming the salts of manganese. Red Oxide of Manganese. 3Mn + 4O. 115.1. This is identical with the oxidum manganoso-manganium of Arfwed- son, and occurs as a natural product. It may be formed arti- ficially by exposing the peroxide or sesquioxide to a white heat. Properties. Color, when finely rubbed, is nearly black when warm, and brownish-red when cold. It is permanent in the air at all temperatures, dissolves in small quantities by cold sulphuric acid, and more rapidly by the aid of chlorine ; 240 Metals. Manganese. the solution has an amethystine tint. It is the cause of the rich color of the amethyst. VarticUe. 4Mn4-7O. 166.8. Sp. gr. 4.531. Known only at a natural production, and first noticed by Mr. Phillips among some ores of manganese, found at Hartshill in Warwickshire. It resembles the peroxide in color, for which it was first mistaken, but may be distin- guished from it by its stronger lustre, greater hardness, more lamel- lated texture, and by yielding water when heated to redness. It i* probably, like the red oxide, a comoound of two oxides, consisting of 2 equivalents of the peroxide, and 1 of the sesquioxide of manganese, with 1 of water. T. Manganic Acid. Mn+3O. 51.7. When peroxide of manganese is mixed with equal weights of nitre, or carbon- ate of potassa, and heated to redness, it fuses, and a gr n- colored mass is formed, known by the name of mint ml chameleon, from the property of its solution to pass through several shades of color. Exp. On the addition of cold water, a green solution is formed, which soon becomes blue, ;,tlu- ble in water and alcohol. T/te Prutobromide of Iron (Fe-|-Br. 106.4) and the Perbrmnide of Iron (HFe -f-3Br. 201 .2) are formed in a similar manner \\ itli tin- i and IMV<- similar properties. Protujflunritlt of Iron. Fe -f F. 4t'. > Ptrfiuoride of Iron (2Fe -J- 3F. 112.04) is formed by dissolving JMT- oxide of iron in hydrofluoric acid. As the acid becomes saturated, crystals are formed in small, white, square tables, which are sparingly soluble in water. Protosulphurct of Iron (Fe + S. 44.1) is prepared by heating equal parts of sulphur and iron-filings in a covered Hessian crucible; considerable heat is evolved, and a yel- lowish-gray substance is formed ; this is completely dissolved, if pure, by dilute sulphuric acid, yielding hydrosulphuric acid. It exists in natilre, in the variegated copjxr />i/r/( r.>, and forms a black precipitate, when hydrosulphate of ammo- nia is mixed with the sulphate of the protoxide of iron. Sesquisulphuret of Iron (2Fe4- 3S. 104.3) is formed by the action of the hydrosulphuric acid on the hydrated peroxide of iron. It has a yellowish-gray color, and dissolves in dilute sul- phuric and hydrochloric acids, with the formation of hydro- sulphuric acid and bisulphuret of iron. Bisulphurct of Iron. Fe + 2S. 60.2. This is the iron pyrites of mineralogists, and occurs abundantly in cubes, or in some analogous form, of a yellow color, and metallic lus- tre ; sp. gr. 4.981 ; so hard as to strike fire with steel ; hence its name. It is dissolved by nitrohydrochloric acid, but by no other acid, except the nitric. By heat, it is converted into magnet- ic iron pyrites, if in close vessels, but exposed to the air, into the peroxide of iron. Magnetic Iron Pyrites. (5Fe + S) + (Fe+2S.) 280.7. This natural product appears to be composed of 5 equivs. of the protosulphuret and 1 of the bisulphuret. It may be formed as above. It is much more easily oxidized than the bisulphuret. Tetrasn'phure,t of Iron (4Fe -}-S. 128.1) and the Disulphuret of Iron (2Fe -|- S. .72) may be formed by passing hydrogen gas, at a red heat, ver the anhydrous sulphate of the protoxide of iron, to obtain the di- Compounds of Iron. 245 sulphuret, and over the disulphate of the peroxide of iron, for the tetra- sulphuret. Properties. They exist in a grayish-black powder, soluble in dilute sulphuric acid, with the evolution of hydrogen and hydrofluoric acid gases. of Iron (2Fe-{-P. 71.7) is prepared by heating the phusphuret in a covered crucible, lined with charcoal. Properties. It is a fused, granular substance, which re- sembles iron in color and lustre, but is very brittle, and ren- ders iron brittle, when contained in it, as it sometimes is. Pcrphosjiliiirrt. of Iron (3Fe-j-4P. 140.8) is obtained by the action of phosphureted hydrogen on sulphuret of iron, and resembles the pre- ceding in most of its properties. Carburets of Iron. Carbon and iron unite in several pro- portions; only three seem worthy of notice graphite, cast or pig iron, and steel. Graphite is known as a natural product, under the names of pi iimb ago and black-lead. There is not more than 10 per cent, of iron, and often not 5. Used for pencils, crayons, crucibles, and for burnishing iron. Cast Iron is a compound of carbon and iron, and is the product of melting the ores of iron with charcoal. Its uses are well known. Steel is formed by filling a furnace with bars of the best malleable iron, with layers of charcoal between, and subject- ing them to strong heat away from the air ; about 1.3 to 1.75 per cent, of carbon combines with the iron. This is the substance used for the various purposes of the arts. It is much harder than iron, but more brittle, also less ductile and malleable, but more firm in its texture, and capable of a higher polish. By fusion it forms cast steel. Protocyannret of Iron (Fe -f- Cy. 54.39) is prepared by mixing in solution cyanuret of potassium with sulphate of protoxide of iron; on exposure to the air, it passes to Prussian blue, Protosulphocyanurct of Iron (Fe -f- CyS 2 . 86.59) is obtained by dis- solving iron in hydrosulphocyanuric acid, and evaporating the pale green solution to dryness in vacua. Sequisulphocyanuret of Iron (2Fe -f- 3CyS*. 231.77) is prepared by mixing the sulphocyanuret of potassium with any salt of the peroxide of iron*. It has a blood-red color, and is a very delicate test of the presence of iron. 21* 246 Metals Zinc Z/wYC. Symb. Zn. Equiv. 32.3. Sp. gr. 7.00. Zinc has long been known in the East, India and China, but was first distinctly noticed in the sixteenth century, by Paracelsus, under the name of zinetum. Henckel is the first who obtained the metal from calaminc, in the year 1701 Von Swab first obtained it by distillation in 1742; and Mar- graff published a process in the Berlin Memoirs in 1"4<>. Natural History. Zinc, like most of the metals, is rarely found pure in nature, but is an abundant substance in com- bination with oxygen, carbon, and sulphur. Process. Commercial zinc, or spelter, is generally ob- tained from calaminc, native carbonate of zinc, or from the native salphuret, called by mineralogists zinc hit ml,. This is oxidized by heating it in the open air, called roasting. It is then distilled ; that is, it is heated in a crucible open at the bottom and closed at the top, to which is affixed a mix-, which terminates just above a basiu of water ; the gaseous products, with the vapor of zinc, pass through the tubr, and the zinc is condensed. The first portions are impure, con- taining cadmium and arsenic, which give the brown blaze ; when the blue blaze is seen, the zinc is collected. It con- tains now some impurities, which are removed by a white heat in an earthen retort, to which a receiver full of wai adapted. Properties. This metal is bluish-white, with a strong metallic lustre and lamellated texture. It is a hard and brittle metal; but between the temperatures of 210 and 300 Fahr., it is malleable and ductile, and in this state is rolled out into plates; fuses at 773 Fahr., and when slowly cooled, crystal- lizes in four or six-sided prisms. It is easily pulverized when heated to a certain temperature below redness, and sublimes at a high temperature in close vessels, without change. Uses. Zinc is used extensively in the arts, for the construction of voltaic instruments, and for covering buildings. It has been pro- posed to use it for culinary vessels, water-pipes, and sheathing for ships; but it is so easily oxidized and acted upon by the weakest acids, that it is unfit for these uses. Compounds of Zinc. 247 Compounds of Zinc. Protoxide of Zinc. Zn + O. 49.3. This is the only known oxide of zinc, formerly called fowers of zinc , nihil album, and philosopher's wooL Process. It is obtained by the combustion of zinc in the open air, in oxygen gas, or by heating Jthe carbonate to red- IKISS. It is found native in Franklin, New Jersey. EX/I Melt zinc in a covered crucible, and when it is at a white heal, rouiove the cover; it will burst out into a white flame, forming tin* o.xide. The Hydrated Oxide of Zinc may "be obtained by uniting a rod of iron and zinc, and placing them in caustic ammonia, i(i a close vessel. ^ *'' : ] ' Properties. At common temperatures it is white, but as- sumes a yellow color when heated to redness ; insoluble in water, and is a strong salifiable base. The oxide is precipitated from its solutions, as a ivhiteliy- dratc, by pure potassium and ammonia, and as a carbonate by alkaline carbonates. The oxide is sometimes substituted for white lead for paint; it is more durable, but not so white. Berzelius describes a suboxide, and Thenard a binoxide, but they are doubtful substances. Chloride of Zinc (Zn -(- Cl. 67.72) is formed by burning zinc-filings in chlorine. It is colorless, fusible a little above 212, and has so soft a consistency at common temperatures, as to be called butter of zinc. Iodide of Zinc (Zn -{- I- 158.6) is prepared by digesting iodine in water with zinc-nhngs. Bromide of Zinc (Zn -f- Br. 110.7) is formed in a similar manner with the preceding. Fluoride of Zinc (Zn -f-F. 50.98) is prepared by the action of hydro- fluoric acid on the oxide of zinc. It exists as a white solid. Sulphuret of Zinc (Zn-j-S. 48.4) is a native product, known by the name of zinc blende. It may be formed by heating sulphur with the oxide; it crystallizes in dodeca- hedrons; lamellated structure ; adamantine lustre; color red, yellow, brown, or black. Cyanuret of Zinc ZnCy. 58.69. CADMIUM. Symb. Cd. Equiv. 55.8. Sp. gr. 8.604. History. Cadmium was discovered in 1817, by Stromeyer, of Gottingen, in an oxide of zinc which had been prepared 248 Metals. Cadmium. r or medical use. Dr. Clark detected it in the zinc ores of Derbyshire, and in the common zinc of commerce, and Mr. Herapath found it in considerable quantities in the zinc works near Bristol, England. Process. The following is the process of Stromeycr : The ore of cadmium is dissolved in hydrochloric or sulphuric acid in excess. The sulphuret of cadmium is precipitated by hydrosulphuric acid. Nitric acid decomposes tins, and forms a nitrate, which is evaporated to dryness. To a solu- tion of this in water, an excess of carbonate of ammonia is added, and the white carbonate of the oxide of cadmium is precipitated, which, when subjected to a red heat, yields a pure oxide. The metallic cadmium is obtained from the ox- ide, by heating it with charcoal. Properties. Cadmium resembles tin in its color and lus- tre, but is harder and more tenacious; very ductile and malleable; melts at about the same temperature as tin, ;md is nearly as volatile as mercury. Heated in the open air, it absorbs oxygen, and is converted into the Oxide of Cadmium, (Cd + O. 63.8,) which is the only known oxide ; is a strong alkaline base, forming neutral >a!i> with acids; insoluble in water; fixed in the fire; and pre- cipitated by all the alkaline carbonates, and by pure ammonia and potassa. Chloride of Cadmium. Cd-fCl. 91.22. This compound is formed by dissolving oxide of cadmium in hydrochloric acid. By concentration, the chloride crystallizes in four- sided rectangular prisms, which lose their water of crystal- lization by he*j, and even in dry air ; fused below redness, and sublimes at a high temperature. Iodide of Cadmium (Cd-f-I. 182.1) is formed in the same way as the iodide of zinc ; soluble in water and alcohol, and crystallizes in large, colorless, transparent, hexagonal tables, which do not change in the air, and have a pearly lustre. By heat they lose water, and then fuse. Sulphuret of Cadmium (Cd-j-S. 71.9) occurs in nature in zinc blende, and is prepared by the action of hydrosnlphuric acid on the salts of cadmium. It has a yellowish-orange color, and may be distinguished from the sulphuret of arsenic by being insoluble in pure potassa, and by sustaining a white heat without subliming. Tin. 249 of Cadmium is a gray compound, very brittle and fusible. T/JV. Symb. Sn. Equiv. 57.9. Sp. gr. 7.2. Tin was known to the ancients, in the time of Moses; siid was obtained, chiefly from Cornwall, England, and Spain, at a very early period, by the Phoenicians. Proffsss. The tin of commerce is obtained from the native oxide by heat and charcoal, and* in the form of block an<1 i^rain tin. Stream Tin is the native oxide of Cornwall, which is found in rounded pebbles, occasioned by the action of water. Tin is seldom perfectly pure, containing a little copper, iron, and arsenic. That from Malacca is the purest. Tin Foil is often an alloy of tin and lead. Block tin is less pure than grain tin. Properties. Tin has a color and lustre resembling silver. It is very malleable. Tin foil does not exceed T jVtf of an kich in thickness, but its ductility and tenacity are inferior to many of the metals. When bent backward and forward, a crackling noise is produced, by which it may be readily dis- tinguished from lead, zinc, etc. It fuses at 240 Fahr, When heated to whiteness, it takes fire. If a drop of the fused tin fall upon a board, it will divide into several globules, and burn with a beautiful white light. The brilliancy of its sur- face tarnishes slowly when exposed to the air at common temperatures, but oxidizes at a high temperature. Compounds of Ti?t. Protoxide of Tin (Sn + O. 65.9. sp. gr. 6.666) is formed by fusing tin for some time in an open vessel, or it may be precipitated, as a hydrated oxide, from a solution of chloride of tin, by an alkaline carbonate. Properties. It is a gray powder, permanent in the air, unless touched by a red-hot body, when it takes fire, and is converted into the peroxide. It is dissolved in the strong cids, and the pure, fixed alkalies. It readily absorbs oxygen from the air and other compounds; hence it throws down 250 Metals. Tin. mercury, silver, and platinum, from their salts. With gold, it causes the purple precipitate of Cassius ; by this charac- ter it is readily distinguished. It is precipitated from its solutions by hydrosulphuric acid as a black protosulphuret. Scsquioride nf Tin (2Sn -f 3O. 130.*) is prepared by mixing recentl y- precipitated and moist hydratcd peroxide of iron with a solution of protochloride of tin. The sesqttioxkle is precipitated in a slimy, gray mailer, of a yellowish tint, from oxide of iron ; distinguished from the protoxide by being soluble in ammonia. Binoxide of Tin (8* -|-2O. ?:l.9) is prepared by tho action of nitric acid on metallic tin. The concentrated arid dors not act on the tin, but, on the addition of water, violent effer- vescence takes place, and a white powder the hv!r it.-d l>i- noxideof tin is formed. The water is expelled by ln-at, and the pure binoxide, of a straw-yellow color, results. The hy- drated oxide may also be precipitated from the protochlond<> by potassa, ammonia, or the alkaline carbonates; but the properties differ from that formed in the other way, the latter being dissolved in the strong acids, while the former is not. It acts the part of a feeble acid, uniting with the pure alka- lies, and forming a clnss of compounds the stnnmit' .-. Binoxide of tin is recognized by its being precipitated from its solutions by hydrochloric acids as a bulky hydrate, and by any of the alkalies or alkaline carbonates. When melted with glass, it forms a white enamel. Protochloride of Tin fSn-f Cl. 93.3*2) is obtained by distilling r^ua! weights of tin and bichloride of mercury. It is a gray s >h'l, ot r ous lustre ; fuses below redness, and sublimes at A high : crystallizes in small, white needles. A solution of the j>r,t. .-;,! ,i id" may be prepared for deoxidizing purposes, by heating granuhitril tin in strong hydrochloric acid, as long as hydrogen gas is evolved. Bichloride of Tin (Sn4-2Cl. 126.74) is formed by distilling - of granulated tin with 24 of bichloride of mercury, or by heating the protochloride in chlorine gas. Properties. It is a colorless liquid, very volatile, yielding white fumes in an open vessel ; hence formerly called the fuming liquor of Libavius ; boils at 248 ; sp. gr. of its vapor, 9.1997; mixed with ^ of its weight of water, it forms a solid hydrate, but dissolves in a larger quantity of water. Uses. The solution called ptrmuriate of tin is used in dyeing, and is prepared by dissolving tin in nitrohydrochloric acid. Protiodide of Tin (Sn -j- I. 184.2) is prepared by heating gran tin with 2 times its weight of iodine. It is a brownish-red substance, very fusible, volatile, and soluble. Biniodide of Tin (Sn-f2I. 3105) is prepared by dissolving the hy- Cobalt. 251 drate of the peroxide, precipitated by alkalies, from the bichloride, in hydriodic acid. . It forms yellow crystals of a silky lustre. Proto sulphur e.t of Tin (Sn-}-S. 74) is prepared by pouring melted tin upon its own weight of sulphur, and stirring rapidly with 'a stick. It has a bluish-gray, or nearly black color, and metallic lustre ; fuses at red heat, and has a lamellated texture when cool. Scsqwsulphuret of Tin (2 Sn-|-3S. 164.1) rs obtained by heating to low redness the protosulphuret with J of its weight of sulphur, ft is a deep grayish-yellow compound. Bisulpkuret of Tin. Sn-j-2S. 90.1. This compound wos formerly called Mosaic gold, and may be prepared by heating a mixture of 2 parts of peroxide of tin, 2 of sulphur, and 1 part of hydrochlorate of ammonia, in a glass or earthen retort, to a low red heat, till sulphur- ous acid ceases to be evolved. Properties. It occurs in crystalline scales, of a golderi- yollow color, and metallic lustre ; soluble in pure potassa, and its only solvent among the acids is the nitrohydrochlo- ric acid. It is obtained, as a hydrate, by the action of hy- drosulphuric acid, and the bichloride of tin, in solution. Terphosphuret of 7Yn(Sn-|-3P. 105) is formed, according to Rose, by the action of phosphureted hydrogen on a solution of protochlo- ride of tin. It oxidizes rapidly in the air. COBALT. Symb. Co. Equiv. 29.5. Sp. gr. 7.834. Cobalt was discovered by Brandt, and derives its name, Kobold, an evil spirit, from the belief of the German miners that its presence was unfavorable to that of valuable metals. Natural History. It exists in nature, generally, in com- bination with arsenic. It is also a constant ingredient in meteoric iron, and is found combined with sulphur and other combustibles. Process. It may be obtained from the oxide, by heating it in connection with charcoal, and then passing over it a stream of hydrogen gas, to combine with the oxygen. Properties. Cobalt is a brittle solid, of a reddish-gray color, and weak metallic lustre; fuses at 130 Wedgwood, and crystallizes when slowly cooled. It is attracted by the magnet, and is susceptible of being rendered permanently magnetic ; absorbs oxygen when heated in open vessels. It is also oxidized by nitric acid, and decomposes water at a red heat. 252 Met 0/5. Cobalt. Compounds of Cobalt. Protoxide of Cobalt (Co + O. 37.5) is obtained by de- composing the carbonate, by heat, in a vessel from which the air is excluded. ' Properties. It has an ash-gray color, and is the base of all the salts of the metal, most of which are a pink-blur. When heated, it absorbs oxygen, and is converted into the peroxide. It is distinguished by giving a blue tint to borax when melted with it Zaffre is an impure oxide of cobalt, obtained by hentinir the arseniuret in a reverberatory furnace. When this sub- stance is heated with sand and potassa, a beautiful 111 in-- colored glass is formed, known by the name of smalt, and used in the arts for communicating the blue color to - porcelain, and earthen-ware. The protoxide is easily precipitated from its salts by alka- lies; the precipitates are of a blue or pale pink color; dis- solved in excess of alkali. | Oxide of Cobalt (3Co + 4O. 120.3) if probably a compound of the peroxide and the protoxide. Peroxide of Cobalt (2Co + 3O. 83) is obtained as a black hydrate with 2 equivs.'of water, when chloride of cobnlt is decomposed by chloride of lime. The water is driven <>} by exposure to a heat of 600 or 700. It combines u ith none of the acids, and, when strongly heated, is decomp< and resolved into the protoxide and oxygen. Chloride of Cobalt (Co + Cl. 64.92) is obtained by dis- solving metallic cobalt, or either of its oxides, in hydrochlo- ric acid. The solution is of a pink color, and yields, on evaporation, small crystals of the same color. When these crystals are deprived of their water of crystallization, they assume a blue color a property on which is founded its use as a sympathetic ink. Ezp. Write on paper with a dilute solution of the chloride, and expose it to a gentle heat; it becomes blue. This solution is called Hillot's sympathetic ink, and is described by some chemists as a mu- riate, of cobalt ; but Turner thinks it a chloride, analogous to several other compounds generally described as muriates of the metals. Exp. Draw the branches of a tree with India ink, and put on the foliage with the chloride of cobalt. When cold, the foliage does not appear, but shows itself on the application of heat. A landscape may Compounds of Nickel. 253 be represented, in this manner, as wintry or vernal, according as the heat is increased or diminished. Sulphurets of Cobalt. Cobalt unites with sulphur in three proportions. The Protosulphurct (Co -|- S. 45.6) is formed "by throwing fragments of sulphur on red-hot cobalt ; has a gray color, a metallic lustre, and crystalline texture. The Sesquisulphuret of Cobalt (2Co-f-3S. 107.3) is formed by pass- ing a current of hydrosulphuric acid gas over the oxysulphuret, at a red heat. Tlie. Bisulphuret (Co-}-2S. 61.7) is prepared by heating below red- ness, in a glass tube, 2 parts of the carbonate of the oxide of cobalt, intimately mixed with 3 of sulphur. Subphosphuret of Cobalt (3Co-f-2P. 119.9) is obtained by the action of pliosphureted hydrogen on chloride of cobalt. It is a pulverulent, gray solid. NICKEL. Symb. Ni. Equiv. 29.5. Sp. gr. 8.2579. Nickel was discovered by Cronstedt in 1751, in the kup- fer nickel (copper nickel) of Westphalia. The term nickel was applied to the ore because it looked like copper, but did not yield it. It exists also in meteoric iron. Process. Nickel may be extracted from the ore, which is an arscniuret of nickel, containing small quantities of sulphur, copper, cobalt, and iron, or from speiss ; also an arseniuret which is obtained in forming smalt from the roasted ores of cobalt. This metal is obtained by heating the oxalate or the oxide with charcoal in close vessels.* Properties. Color white, intermediate between tin and silver; strong metallic lustre; ductile arid malleable; at- tracted by the magnet, and, like iron and cobalt, may be rendered permanently magnetic ; a little less infusible than iron ; oxidized at a red heat, and by nitric acid. Compounds of Nickel. Protoxide of Nickel (Ni-|-O. 37.5) is formed by heating the carbonate, oxalate, or nitrate, to redness, to drive off the acid. * For processes, see Turner's Elements, p. 351. 22 254 Metals. Arsenic. Properties. Color at first an ash-gray, but, when exposed to a white heat, it is of a dull olive-green. This is the strong alkaline base of the metal, and nearly all the salts have a green tint. Pure alkalies precipitate this oxide from its salts, as a hydrate of a pale green color. The alkaline carbonates and hydrosulphurets also precipitate it from its salts, the former as a carbonate, the latter as a sulphuret of a black color. Sesquioxlde of JYYdW (2Ni + 3O. 83) is formed by transmitting chlorine through water, in which the hydrate of the protoxide is sus- pended. It has a black color, does not unite with acids, and is decom- posed at a red heat. Cltlnrnit <>J\\ickel (Ni-j-Cl. 64.92) is formed by the action of hydro- chloric acid upon metallic nickel, or one of its oxides; an in. r.ijd- green solution is formed, and, on evaporation, yields crystals ol tin- same tint, which deliquesce in moist air, and effloresce if lite, air is dry. Protofuljihuret of Mfkcl (Ni + 8. 45.6) is formed by a similar pro- cess with the protosulphuret of cdbalt ; occurs native in acicular crystals the lioarkic* of the Germans. When dry, it is of a grayish- yellow color, while the precipitates are dark brown ; soluble in nitric or nitrohydrochloric acid. Ditulphuret ofXickd (2Ni + S. 73.1) is obtained by passing hydro- gen gas over the sulphate of nickel at a red heat; color light yellow, and is more fusible than the preceding. Subphofphurtt , { f .YiVAW (3Ni+2P. 110.9) is obtained by the action of hydrogen on subphosphate of oxide of nickel. Color black, solu- ble in nitric acid, and burns with a flame under the blowpipe. Cyanuret of Mckel (Ni-f-Cy. 55.89) is obtained by mixing in solu- tion a salt of nickel with cyanuret of potassium. A precipii formed, of a pale, apple-green color, which becomes tinged with yellow on drying. SECT. 2. METALS WHICH DO NOT DECOMPOSE WATER AT ANY TEMPERATURE, AND THE OXIDES OF WHICH ARE NOT REDUCED TO THE METALLIC STATE BY THE SOLE ACTION OF HEAT. j*ftSEJY7C. Symb. As. Equiv. 37.7. Sp. gr. 5.8853. Arsenic was first discovered by Dioscorides, who called it Sandarac; but its properties were first investigated by Brandt, in 1733. Natural History. It exists in nature, in small quantities, rarely in a metallic state. It is generally found in com- Compounds of Arsenic. 255 bination with cobalt and iron, and occasionally with other metals Process. Metallic arsenic is obtained by roasting the ores in a reverberatory furnace ; as the arsenic is expelled by heat, it combines with oxygen, and condenses into thick cakes on flu- chimney. These cakes are purified by a second sublima- tion, and constitute the white oxide of arsenic a virulent poison. This substance is then mixed with twice its weight oi' bleu k flux * exposed with charcoal to a red heat in a Hes- sian crucible; and the metal is sublimed and collected in an empty crucible, which is placed over the other, and kept cool for the purpose of condensation. Properties. Arsenic is a very brittle metal, of a steel-gray color, high metallic lustre, and of a crystalline structure. When heated to 356, it sublimes without fusion, and may be collected in close vessels without change ; but, when thrown on a red-hot iron, it burns with a blue flame and white smoke, giving off a strong odor of garlic a property which belongs to no other metal, unless it be zinc; when thus heated in the open air, it is converted into the white oxide of arsenic. Exposed at common temperatures of the air, it oxidizes slowly, forming the substance called jly-powder, which is a mixture of the oxide and the metal. Arsenic detonates with some of the salts, and decomposes them. Exp. Take 3 parts of chlorate of potassa, and 1 of arsenic, finely powdered, and cautiously mixed together. 1. Place a small quantity on an anvil, and strike it with a hammer; the arsenic will instantly combine with the salt, producing an explosion with flame. 2. Set it on fire, and it will burn rapidly. 3 Throw it into concentrated sulphuric acid, and a bright flash of light will be perceived at the moment of contact. Uses. Arsenic is used in the arts. It renders glass white. Compounds of Arsenic. Arsenious acid, (2As-|-3O, 99.4,) commonly called white arsenic and white oxide of arsenic, may be formed by the * Prepared by detonating, in a crucible, 1 part of nitre with 2 of the crystals of tartar. 256 Metals. A rsenic. combustion of the metal ; but the white arsenic of commerce is obtained from the arseniurets of cobalt, by sublimation. Properties. Arsenious acid is white, semi transparent, and, when first formed, of a vitreous lustre and conchoid ;ti fracture. Its acid taste is owing to the inflammation which it produces ; it has a faint impression of sweetness. Its sp. gr. is 3.7; has two crystalline forms, but is usually found in six-sided scales, derived from a rhombic prism ; soluble in water. It is one of the most virulent poisons known ; and, as it is sometimes accidentally or intentionally taken, it is a frequent cause of death, and a subject of judicial investigation. Hence the importance of pointing out the most effectual modes of detecting its presence. Tests. The most valuable are the ammoniac o-nitr ate of silver, ammoniaco-sulphate of copper, hydrosulphuric acid, and hydrogen gas. 1. Obtain as large a quantity of the liquid from the stom- ach as possible. This, with parts of the stomach, should be put into pure water, filtered and evaporated, so as to obtain a concentrated solution; add to this, ammoniacal nitrate of silver,* and if arsenic is present, a yellow arseniate of sil- ver will be thrown down. 2. Add to the suspected liquid ammoniacal sulphate of copper,t and a green precipitate will be formed, called Scheele's green. 3. Pass into the liquid, hydrosulphuric acid, and if aryni- ous acid is present, orpiment, or the sesquisulphuret of arsenic will be formed, giving to the liquor a yellow, turbid appearance. This sulphuret should then be dried, mixed with black flux, carefully introduced into a glass tube, and heated by a spirit lamp; the sulphuret will be decomposed, and metallic arsenic appear on the cool parts of the tube. This is a very satisfactory test ; but if, on heating the sub- * Prepared by dropping into a strong solution of ni train of silver, ammonia, till the oxide of silver, first precipitated, is nearly all dis- solved. t Prepared in Ihe same way with the preceding, by using the sul- phate of copper, instead of the nitrate of silver. Compounds of Arsenic. 257 stance thus deposited, it rises up in white fumes, with an alliaceous odor, and is deposited in white, octohedral crystals, we may be sure that arsenic is present. 4. Introduce a quantity of the suspected liquid into a Florence flask, having a jet pipe and a stop-cock attached, with zinc and sulphuric acid; the water will be decomposed, and the nascent hydrogen, in passing through the water con- taining arsenious acid, will form arseniureted hydrogen; and on burning the gas, as it issues from the jet, metallic arsenic will be deposited on a plate of glass or porcelain, held over the flame. Any one of these tests, however, should not be depended upon in a case where the life of a fellow-being is at stake, as other metals, such as antimony, will sometimes present a similar appearance; but if the suspected substance be tested by each of the four ways mentioned, there can be no doubt but that it contains arsenious acid. Its action upon animals, whether taken into the stomach, or applied to wounds, is attended by pain and vomiting; and if life be prolonged beyond twenty-four hours, diarrhoea, a sensation of heat, and extreme pain in the stomach and intestines, succeed, pulse feeble, countenance anxious, skin livid, often attended by eruptions. The best antidote is per hydrate of iron, with a small quantity of am- monia. In cases rapidly fatal, extreme faintness, cold sweats, attended with slight convulsions, are experienced. (See Christison on Poisons.) Arsenic has the properly of preserving from decay the bodies of those poisoned with it. The stomach and intestines have thus been found entire two years and a half after death. Arsenic Acid (2As-|-5O. 115.4) is formed by dissolving arsenious acid in concentrated nitric, mixed with a small quantity of hydrochloric acid, distilling in a glass vessel until it acquires the consistency of sirup, and then heating nearly to redness, in a platinum crucible, to expel the nitric acid. Properties. It has a sour, metallic taste, reddens the vege- table blue colors, and combines with alkalies, forming arse- niates. It is decomposed by hydrosulphuric acid. This acid is also an active poison. Protochloride of Arsenic (AsCl. 73.12) is prepared by heating in a retort, to nearly 212, arsenious acid, with ten times its weight of con- centrated sulphuric acid, and throwing them in fragments of common salt. SesquirhJoride of Arsenic (As 2 Cl 3 . 181.66) is formed by the sponta- neous combustion of powdered arsenic in chlorine gas. It is a color- 22* 253 Metals. Chromium. less, volatile liquid, giving off fumes, on exposure to the air; hence called fuming liquor of arsenic. Periodidl of Arsenic (2As-|-51. 706.0) is formed by gently heating arsenic with iodine. It is a deep red compound, decomposed by water. Protohyduret of Arsenic (As-f-H. 38.7) is prepared by the action of water on an alloy of arsenic and potassium. Sesquibromide of Arsenic'. 2As + 3Br. 310.6. When arsenic and bromine are brought into contact, they instantly unite with vivid evo- lution of light and^heat. Arscniurcted Hydrogen. 2As-|-3H. 78.4. This gas was discovered by Scheele. It is generally made by digest- ing an alloy of tin and arsenic in hydrochloric acid. It is colorless; has a fetid odor resembling garlic; sp. gr. 2. ()<).">: extinguishes burning bodies, but burns with a blue flame. It is poisonous in a high degree, having proved fatal to Ai. Gehleu. It is decomposed by chlorine, iodine, caloric, and even atmospheric air; it forms with oxygen an explosive mixture. Protosulphuret of Arsenic. As+S. 53.8. This subst .-H-T exists in the mineral kingdom, and is called realgar. It may be formed by heating arsenious acid with half its weight of sulphur, until the mixture is perfe/itly fused. It is ocys- talline, transparent, and of a ruby-red color. Sesquisulphurct quisulpkvret of Chromium (2Cr -{-38. 104.3) may be obtained by heating in close vessels a mixture of sulphur and the hyd rated oxide. It is ofa dark-gray color, acquiring a metallic lustre by irictimi. Protophosphuret of Chromium (Cr-fP or CrP. 43.7') is prepared by passing phosphureted hydrogen gas over the sesquichloride of chro- mium at a red heat; a black compound, burning before the blowpipe, with a flame of phosphorus. VANADIUM. Symb. V. Equiv. 68.5. Vanadium was discovered by Sefstrom, in 1830. It de- rives its name from Vanadis, a Scandinavian deity. Natural History. It exists in the iron ore of Taberg, Sweden, and is found in great abundance in the slag formed by .converting the cast iron of Taberg into malleable iron. It was also found by Johnson, at Wanlock-Head, Scotland, where it occurs as a vanadiate of lead. Process. It has been obtained in various ways by heat- ing vanadic acid with potassium, and by the decomposition of the chloride of vanadium.* Properties. When obtained by means of potassium, it is a brittle, black substance ; but when prepared by decompo- sing the chloride, it is white, resembling silver, of a strong metallic lustre. It is not oxidized by air or water ; boiling sulphuric, hydrochloric, and hydrofluoric acids do not affect it, but it is dissolved by nitric and nitrohydrochloric acids, and the solution has a fine, dark blue color. * For processes, see Turner's Elements. Compounds of Vanadium Molybdenum. 261 Compounds of Vanadium. Protoxide of Vanadium (V-f-O. 7G.5) may be obtained by heating vanadic acid with charcoal or hydrogen gas. It is a dark brown, or black, substance, soluble in nitric acid. Binoxide of Vanadium (V-J-2O. 84.5) may be prepared by heating to full redness 10 parts of the protoxide, with 12 of vanadic acid, in a vessel filled with cnrbonic acid. It is black, very infusible, and insolu- ble jn water. Its salts have a blue color. It acts the part of an acid by uniting with alkaline bases. Vanadic Acid ( V -(- 3O. 92.5) is tasteless, insoluble in alcohol, and very slightly soluble in water. It is easily de- composed by heating it with combustible matter, and in solu- tion by all deoxidizing agents. It unites with bases often in two or more proportions ; most of its neutral salts are yellow. It is distinguished from all other acids, except the chromic, by its color, and from this acid by the action of deoxidizing substances, which give a blue solution with the former, and green with the latter.* MOLYBDENUM. Symb. Mo. Equiv. 47.7. Sp. gr. 8.615. Molybdenum was discovered in 1775. Process. It was obtained from the native sulphuret, by digesting it in nitrohydrochloric acid, and heating the mo- lybdic acid, thus formed, in connection with charcoal. Properties. It is a brittle metal, of a white color, and very infusible. Its properties are imperfectly known. Protoxide of Molybdenum (Mo-f-O. 55.7) is obtained by precipitating the hydrochloric solution of molybdic acid by zinc, when a brown hydrate is formed, giving dark colored solutions with the acids. Binoxide of Molybdenum (Mo -j- O. 63.7) is prepared by putting a mixture of molybdate of soda and sal-ammoniac, in fine powder, in a red-hot crucible, instantly covering it, and continuing the heat until * The bichloride of vanadium, (VC1 2 . 68.5 + 70.34 = 139.34;) the tercldoride of vanadium, (VCR 68.5 + 106.26 = 174.76 ;) the bibromide of ramulium, ( VBr 2 . 68.5 -f- 156.8 = 225.3 ;) the bisuljthuret of vana- dium, (VS 2 . 68.5 -(- 32.2 = 100.7 ;) the tersulphuret, (VS 3 . 68 5 -f 48.3 = llf).8,) are unimportant compounds, for a description of which, see Turner's Elements, p. 365. 262 Mttah. Tungsten. vapors of sal-ammoniac cease to arise. This is a deep brown anhydrous powder, insoluble in acids. Molybdic Acid .(Mo-f 3O, or MO 3 71.7) may be obtained by roasting the native sulphuret in an open crucible, kept at a low red heat, and stirred until sulphurous acid ceases to escape. The yellow powder, thus formed, is treated with ammonia ; the filtered solution evaporated, again dissolved in water and ammonia, and crystallized ; the ammonia is then expelled by gentle heat. It is a white powder ; sp. gr. 34.9 ; fuses at a red heat into a yellow liquid ; slightly soluble in water.* TVNGSTEJt. Symb. W. Equiv. 94.8. Sp. gr. 17.5. Tungsten is found native in the mineral wolfram. Process. It is obtained by exposing a mixture of tungstic acid and charcoal to a strong heat. Properties. It is a very hard, brittle metal, resembling iron in color, and, by the action of heat and air, converted into tungstic acid. Compounds of Tungsten. Binoxide of Tungsten (W + 2O. 110.8) is prepared by the action of hydrogen gas on tungstic acid, at a low red heat. It has a brown color, resembling copper when polished. Tungstic Acid (W + 3O. 118.8) may be obtained by heating the binoxide to redness in open vessels. It is of a yellow color, insoluble in water, and has no action on litums paper. Bichloride of Tungsten (W + 2C1. 165.64) is formed by heating tungsten in chlorine gas.t * For the preparation of the protochloride of molylnl2.42 ;) the Sesquicltliirulr of Uranium, (2U -+-3C1. 540.26,) and the Sulphuret of (7rantum,are un- important compounds. (See Turner, page 380.) CERIUM.* Symbr. Ce. Equiv. 46. Cerium was obtained, by Hisinger and Berzelius, from a mineral called cerite. It exists also in the mineral called allanite, as an oxide, which is very difficult to be reduced to the metallic state. Vauquelin obtained a small globule, not larger than a pin's head, which was not acted upon by any of the simple acids, and but slowly dissolved by the nitro- hydrochloric. Compounds of Cerium. Protoxide of Cerium (Ce + O. Eq. 54) is a white powder, insoluble in water. The salts, which are soluble, have an acid re-action. Sesquioxide of Cerium (2Ce +3O. 1 10) is obtained from cerite, and is a fuwn-red substance, soluble in several of the acids. Protochloride of Cerium. Ce-f-Cl or CeCl. 46 -f- 35.42 = H I.'. Sesquickloride of Cerium . 2Ce + 3C1 or Ce'Cl 3 . 92 + 1 06.26 = 1 '. - . -J > Protosulphuret of Cerium. Ce + S or CeS. G21. (See Turner's Chemistry, p. 381.) BISMUTH. Symb. Bi. Equiv. 71. Sp. gr. 9.822. Native Bismuth occurs in crystals, octohedra, or cubes, containing arsenic and cobalt. It is also found combined with sulphur and oxygen, from which it is obtained by the aid of heat and charcoal. Properties. It is a brittle solid, generally composed of broad plates of a reddish-white color, very fusible ; melts at 476 Fahr., and forms very fine crystals by slow cooling. Exp. For this purpose, fuse a quantity of it in a crucible, and let it cool until a crust is formed ; break the crust and pour out the fluid be- * So called from the planet Ceres, discovered about the same period. Titanium. 267 neath ; the inner surface will be lined with beautiful crystals. Under the compound blowpipe it burns with much brilliancy, producing yellow fumes of protoxide. Protoxide of Bismuth (Bi + O. 79. Sp. gr. 8.211) may be formed as above. It forms salts, most of which are white; sublimes at a high temperature ; fuses at a full red heat into a brown liquid. If the nitrate of the protoxide be thrown into water, a white precipitate is thrown down, formerly called magistery of bismuth, and pearl white, which is some- times used as a paint, for improving the complexion. Sesquioxide of Bismuth (2Bi-f-3O. 160) is formed by fusing potassa with the protoxide of bismuth. It is a brown, heavy powder, little dis- posed to unite with acids, or alkalies. Chloride of Bismuth (Bi-j-Cl. 106.42) is formed by the spontaneous combustion of bismuth in chlorine gas, formerly called butter of bismuth. It is of a grayish-white color, and granular text are. Bromide of Bismuth. Bi -f- Br. 71 -f 78.4 = 149.4. Sulphuret of Bismuth (Bi-j-S. 87.1) is found native. TITANIUM. Symb. Ti. Equiv. 24.3. Sp. gr. 5 3. Titanium was first noticed by Mr. Gregor, of Cornwall. Klaproth gave it the name of titanium, after the Titans of ancient fable. But its properties were determined by Wol- laston, in 1822, who found it in the slag of an iron-smelting furnace in South Wales. Properties. Its color is red, resembling copper. It exists in small cubes, which are so hard as to scratch rock-crystal, and very infusible. It generally contains traces of iron. The pure metal is obtained by heating the chloride with am- monia in a glass tube, when it appears in the form of a deep blue colored powder, which is apt to take fire, if exposed to the air when warm. Compounds of Titanium. Oxide of Titanium (Ti -f- O. 32.3) is obtained by exposing titanic acid to a strong heat in a black-lead crucible. It is of a purple color. Titanic Acid, (Ti-f-2O. 40.3,) also called peroxide of titanium, exists in the minerals anntase and rutile. from which the acid is obtained by the aid of heat and hydrosulplmric acid gas.* * For processes, see Turner's Elements. 268 Met ah. Tellurium. Properties. Titanic acid is of a white color; very infusi- ble, and when once ignited, insoluble in acids, excq>t in the hydrochloric. It is a feeble acid, resembling the silicic. If it is ignited with potassa, and dissolved in hydrochloric acid, a solution of gall-nuts will produce an orange-red color, which is very characteristic of titanic acid. Bichloride of Titanium (Ti + 2Cl. 95.14) was discovered in 1824, by Mr. George, of Leeds, by transmitting dry chlorine gas ovi-r titanium at a low red heat. Properties. A transparent, colorless liquid, which boils at 212. The density of its vapor is 6.615; combines with water with explosive violence from the evolution of intm heat ; on exposure to the atmosphere, it emits dense white fumes, of a pungent odor, similar to chlorine. Bisulphuret of Titanium. Ti + 2S. Eq. 24.3 + 32.2 = 56.5. TELLURIUM. Symb. Te. Equiv. 64.2. Sp.gr. 6.115. Tellurium is a rare metal, found only in small quantities in Transylvania and Connecticut. It was first noticed by Miil- ler, in 1782, but its existence was more fully established in 1798, by Klaproth, who called it tellurium, from tellus, the earth. It is found chiefly in combination with gold and silver. Properties. It is ~a brittle metal, of a bright gray color ; very infusible and volatile. Heated in the air, it burns with a sky-blue flame, edged with greeji; placed upon charcoal before the blowpipe, it inflames with violence, and flies en- tirely off in gray smoke, having a peculiarly nauseous smell. Compounds of Tellurium. Tellurous Acid, (Te + 2O. 80.2,) also called oxide of tel- lurium, is generated by the action of nitric acid on tellurium. It is a white, granular powder, resembling in many of its properties the titanic, and several other feeble acids. Its aqueous solution reddens litmus paper. The other compounds are the Telluric Jciil, (Te -f- 3O. RS.2;) Chlo- ride of Tellurium, (Te + Cl. 99.G2 ;) Bichloride, (Te + 2C1. 135.04;) Bisulphuret. (Te4-2S. 96.4:) Persulphurtt and Hudrotelluric rfcid, (Te-f H. 65.2.) Copper. COPPER. Symb.Cu. Equiv.31.6. Sp. gr. 8.895. Copper, from cuprum, a name derived from the island Cyprus, has been known from the remotest ages. Natural History. It is found native, and in combination with other substances, especially with sulphur. The copper of commerce is chiefly obtained from the native sulphurets. It exists in great abundance in Cornwall, and other parts of Europe, in Liberia, and in America. Schoplcraft found a mass of native copper about thirty miles from Lake Superior, which weighs, by estimation, 2000 Ibs. Process. It may be obtained perfectly pure, by dissolving the copper of commerce in hydrochloric acid, diluting the solution, arid immersing in it a clean plate of iron, upon which the copper will be precipitated. Properties. Copper is distinguished from all other metals, except titanium, by its red color. It is very ductile and malleable; melts at 1996 Fahr. ; burns before the com- pound blowpipe with a beautiful green flame, and if a fused globule be thrown into a glass jar, two feet high, filled with water, it will pass in full ignition to the bottom, and remain some time at a red heat. Uses. Copper is one of the most useful metals, being em- ployed extensively in most of the arts of life. Compounds of Copper. Red, or Dioxide of Copper (2Cu + O. 71.2) is found native in octohedra) crystals. Process. It may be prepared artificially, by heating, in a covered crucible, a mixture of 31.6 parts of copper-filings with 39.6 of the black oxide. Properties. It resembles copper in color ; sp. gr. 6.093 ; soluble in ammonia, and the solution is colorless, but it absorbs oxygen on exposure to the air, which produces a blue color, owing to the formation of the black oxide. 23* 270 Metals. Alloys of Copper. Black, or Protoxide of Copper. Cu + O. 39.6. This is the copper- black of mineralogists, and is formed by the spontaneous oxidation of other ores of copper. Properties. It varies from a dark brown to a bluish-black color, according to the mode of formation; combines with most of the acids, and its salts have a green or blue tint. It forms with ammonia a deep blue solution, which distinguishes it from all other substances. The salts of the protoxide of copper are mostly distinguished by their color. Metallic copper is separated from the salts by a rod of iron- or zinc. Binoxide of Copper. Cu + 2O. 31 6 + 16 = 47.C. Dichlnridc of Copper (2Cu + Cl. 98.02) is formed by the spontane- ous combustion of copper-filings in chlorine gas. It is of various colors, white, yellow, and dark brown, according to the mode ofpreparation ; soluble in hydrochloric acid, but not in water. Chloride of Capper; Cu -f- Cl. 67.02. Diniodide. of Copper ; 2Cu -f- I. 63.2-4-120.3 = 189.5. Sitlphuret of Copper (ru + S. 47.7) is a constituent of copper pyrites, in which it is combined with protnsul- plmrt't of iron. Triphosphuret of Copper; 3Cu-f-P. 110.5. Subse- iiuiphosphuret ; 3Cu-r-2P. 126.2. Cyanurel of Copper; Cu-f-Cy. 57.99. Disulphocyanuret of Copper; Cu + CyS'. 03.2 -f- (2G.:t9 + 32. 2) == 121.79. (See Turner's Elements, p. 389.) Tests. The best mode of detecting copper in mixed liquids is the hydrosulphuric acid. The sulphuret, after being collected, and h< at. d to redness in order to char organic matter, should be placed on a pn .- of porcelain, and be digested in a few drops of nitric acid ; sulplmtr (' the protoxide of copper is formed, which, when evaporated to dryness, strikes the characteristic blue tint on the addition of ammonia. T. Alloys. The alloys of copper are very important and use- ful substances. Brass is an alloy of copper and zinc. The best bra-- consists of four parts of copper to one of zinc. Tutum" contains in addition a little iron. Tombac, Dutch Gold, Si- milor, Prince Rupert's Metal, arid Pinchbeck, contain more copper than brass. Bell-metal and Bronze are alloys of cop- per and tin. The best proportion for bell-metal is 3 parts of copper to 1 of tin; for bronze, 8 to 12 of tin to 100 of copper. In these alloys, according to Dalton, the elements combine in definite proportions. Poisonous Properties of Copper. Copper vessels used for culinary purposes should be coated with tin, as the oxide is poisonous. This is done by making the surface of the copper bright, rubbing over a little sal-ammoniac to prevent oxidation, and then heating the vessel and rubbing it with rosin and tin. Lead. 271 LEAD. Symb. Pb. Equiv. 103.6. Sp. gr. 11.352. Lead was well known to the ancients. It is rarely found native, but its ores are abundant, the most important of which is the sulphuret or galena, from which the pure metal is chiefly obtained.* Berzelius obtained the metal perfectly pure by heating the pure nitrate of lead, mixed with charcoal, in a Hessian crucible. Properties. The properties of lead are generally well known. It is of a bluish-white color, soft, malleable, and ductile; fuses at 612, and by slow cooling, crystallizes in octohedra. The proper solvent of lead is nitric acid. Compounds of Lead. Protoxide of Lead (Pb + O. 111.6. Sp. gr. 9.4214) is prepared by heating the rnetal to a high temperature, and col- lecting the gray film which forms on the surface. This is exposed to heat in open vessels, until it acquires a uniform yellow color, and constitutes the massicot, and when partially fused, the litharge of commerce. This is always mixed with the red oxide ; it is obtained perfectly pure by adding ammo- nia in excess to the nitrate in solution, washing the precipi- tate in cold water, and, when dry, heating it to redness foiuan hour in a platinum crucible. Properties. Its color is red when hot, but acquires a rich lemon-yellow when cold ; fuses at a bright red heat, and, after fusion, has a highly-foliated texture ; insoluble, in water ; unites with acids, and forms the base for all'the salts of lead. It 'is precipitated from its solutions by pure alkalies as a ^_ _J> i i * Process. The ore, in the state of coarse powder, is heated in a reverberatory furnace, when part of it is oxidized, yielding sulphate of protoxide of lead, sulphuric acid which is evolved, and free oxide of lead. These oxidized portions then re-act on sulphuret of lead, by the re-action of 2 equivalents of oxide of lead, and 1 of the sulphuret; 3 equivalents of oxide of lead and 1 of sulphuric acid result, while 1 equivalent of the sulphuret and 1 of the sulphate mutually decompose each other, giving rise to 2 equivalents of sulphurous acid, and 2 of metallic lead. The lead of commerce commonly contains silver, iron, and copper. T. 272 Met ok. Lead white hydrate, which is re-dissolved by potassa in excess , asr a white carbonate, which is the well-known pigment white Irafl, by alkaline carbonates ; as a white sulphate, by soluble sulphates; as a dark brown sulphuret by hydrosulphuric acid ; and as a yellow iodide of lead, by hydriodic acid, or iodide of potassium. T. Metallic Lead is separated from the salts of the protoxide by iron or zinc. Erjt. In a solution of 1 part of acetate of lead in 24 parts of water, contained in a glass bottle, suspend a piece of zinc by a tlm-ad. Tin- lead will be deposited upon the zinc in a form resembling a tree a peculiar appearance, called arbor Saturni. Uses. Protoxide of lead enters into the composition of flint-glass, and is employed for glazing earthen-ware and por- celain. Peroxide of Lead (Pb + 2O. 119.G) is formed by the action of nitric acid upon the red oxide, or minium of commerce. It is of a puce color, insoluble in water, and resolved by strong oiygen acids into a salt of the protoxide and oxygen gas. Red O/idr of Lead (3 Pb + 4O. 342.8) is prepared by heating lead in the air nearly to the point effusion, by which it is oxidized. It is then exposed to a temperature of <>(M)' or 700, while a current of air passes across its surface. It slowly absorbs oxygen, and is converted into the mhihnn of commerce. It is employed as a pigment, and in the manu- facture of flint-glass, but does not unite with acids and form salts. Chloride of Lead (Pb-f-Cl. 130.02) is obtained by adding hydro- chloric acid to a solution of acetate or nitrate of lead. It is sometimes called horn lead ; dissolved in hot water, it appears, on cooling, in small, acicular, anhydrous crystals, of a white color. Iodide of Lead; Pb-fl. 229.9. Bromide of Lead; Pb + Br. 182. Fluoride of Lead ; Pb + F. 122.28. Sulpkuret of Lead ; Pb -f- 8. 11 9.7. Phosphvret of Lead and Carburet of Lead, composition uncertain. Cy- anuret of Lead; Pb-f- Cy. 129.99. (See. Turner's Elements, p. 393.) The salts of lead are generally poisonous, of which the carbonate is the most virulent. Alloys of Lead. Common pncter is an alloy of 20 parts of lead and 80 of tin. Fine solder consists of 1 part of lead and 2 of tin, and is employed for tinning copper. Coarse solder contains one fourth of tin, and is used by plumbers. Pot metal is an alloy of lead and copper. Mi-miry. 273 X SECT. 3. METALS, THE OXIDES OF WHICH ARE REDUCED TO THE METALLIC STATE BY A RED HEAT. MERCURY, or QUICKSILVER. Symb. Hg. Equiv. 202. Sp. gr. 13.568. Mercury was well known to the ancients. Its principal ore is the sulphuret or native cinnabar, from which it is separated by distillation with quick lime, or iron-filings. Properties. Mercury is the only metal which retains its liquid form at common temperatures. It is of a tin-white color, and strong metallic lustre ; boils at 662 Fahr., and congeals at 40 below zero, in which state it is malleable, and has an increased specific gravity 15.612. It is not tar- nished by exposure to cold, moist air, unless it contain other metals. It is sometimes adulterated with an alloy of lead and bismuth, which renders it less fluid and volatile, leaving a residuum when boiled in a silver spoon. Mercury is not acted upon by any of the acids except the sulphuric and nitric. It is used for collecting those gases which are absorbed by water; also for barometers, thermometers, and for forming connections in voltaic circles. Compounds of Mercury. Protoxide of Mercury (Hg-j-O. 210) is prepared by mixing calomel with pure potassa in excess in a mortar, and stirring it briskly to effect a rapid decomposition. The pro- toxide is then washed in cold water, and left to dry in a dark place. Properties. It is a black powder, insoluble in water, com- bining with acids, and bui feebly with alkalies. The alkalies precipitate it from the solution of its salts, as a black protox- ide. The best test of its presence is the hydrosulphuric acid, by which it is thrown down as a black protosulphuret. 274 Metals. Mtrrury. Binoxide of Mercury (Hg+-2O. 218) is commonly known by the name of red precipitate.* Process. Peroxide of mercury may be prepared by dissolving mer- cury in nitric acid, and exposing the nitrate thus formed to a fempera- ture just sufficient to expel the whole of the nitric acid. It may aU<> In- formed by exposing mercury in a matrass, with a long tulie, to tin- agency of heat and air, for the space of three or font weeKs. Properties. It exists in shining, crystalline scales, nearly black when hot, and red when cold; slightly soluble ::i water. The solution has an acrid, metallic taste, and is poi- sonous. This oxide is separated from all acids by the carbonated fixed alkalies, and is reduced to the metallic state by copper. Protochloride of Mercury (Hg-{-Cl. 237.42) is common- ly called calomel, and was first mentioned in the seventeenth century, by Crollius. Process. It may be obtained by bringing chlorine gas in contact with mercury, but it is more commonly prepared by sublimation. This is done by mixing 1 equiv. of the bichloride with 1 eqmv. of mercury, until the metallic globules entirely disappear, and then subliming. To purify it from corrosive sublimate, which is always mixed \\ itli it, when first prepared, it must be reduced to powder, and well washed, \\li.n it will be fitted for chemical or medical purposes. The proto- chloride is also found native, and called horn quicksilver. Properties. When obtained by this process, calomel ex- ists in semi-transparent, crystalline cakes, of a yellow color when warn), but white when cold ; sublimes a little below a red heat, and n part of it is resolved into mercury, and the bichloride. It is insoluble in water, and is tlecomp by the pure alkalies. Used extensively for medical purposes; acts powerfully upon the glandular system. Bichloride of Mercury (Hg-J-2Cl. 272.84) is formed by heating mer- cury in chlorine gas. During the process, the metal burns with a pale red flame. It is prepared fur mediea! purposes hy subliming a mixture of bisulphate of the peroxide of m. icury with chloride of sodium, or sea-suit. . Bichloride of mercury, commonly called - rtttirt HssVtffnaftj is ;\ most virulent poi.M. It sublimes in the form of a dense, white vapor, when heated, * This is t!.e hydrargyri oxidum rubrum of the pharmacopolist. Compounds of Mercury. 275 powerfully affecting the mouth and nose ; soluble in hydro- chloric, nitric, and sulphuric acids, and is decomposed by the alkalies, and several of the metals.* Tests. Place a drop of the suspected liquid on polished gold, and touch the moistened surface with the point of a penknife ; the part touched will instantly become white, owing to the formation of an amalgam of gold". Some animal and vegetable substances convert the bichloride into calomel ; the best is albumen, made by mixing the white of an egg in water , hence the white of an egg is an antidote to poisoning by cor- rosive sublimate. Protosulphutet of Mercury. Hg + S. 218.1. Bisulpkurct of Mercury (flf mercury. It is colorless, inodorous, and highly poisonous. Amalgams. Mercury combines with most of the metals, and forms a class of compounds called amalgams. An amalgam of one part of potassium and seventy of mercury is hard and brittle ; on adding mercury to the liquid alloy of potassium and sodium, solidification and combustion rnsue. Two parts of mercury, one of bismuth, and one of lead form a liquid amalgam, from which cubic crystals of bismuth are slowly formed. The combination of mercury with those metals which are not easily oxidized, enables them to combine with oxygen ; hence gold and silver, in combination with mercury, are easily oxidized by heat and air. With tin, it forms an amalgam for coating mirrors. * Pr of iodide of mercury ; Hg + I. 328.3. Scsqu iodide; Hg 2 ! 3 . 782.9. Biniodidc ; Hgl*. 454.6.' Protobromide ; HgBr. 280.4. Bibromidc of mercury; Hg-f-2Br. 358.8. lodurctcd bichloride of mercury; 20HjrCl a 4- 1. 5583. 1 . lodobichloride of mercury ; 40HgCl 2 + Hgl*. 1 1368.2. 276 Metals. Silver. SILVER* Symb. Ag. Equiv. 108. Sp. gr. 10.51. Silver has been known from the earliest ages. It is found native, and in combination with other substances. The native silver occurs in octohedral or cubic crystals, seldom perfectly pure ; it is generally found in primitive formations. Peru and Mexico contain the richest mines of native silver which are known. Preparation. Pure silver may be obtained from standard silver, by dissolving it in nitric acid and introducing a clean piece of copper. The metal will be precipitated upon the copper; this is then to be washed in pure water, and di- gested in ammonia to remove the copper. A better pro- cess is to decompose the chloride of silver by carbonate of potassa. Silver is often obtained from the argentiferous sulphurct of lead, by a process called eifpeJZdffM.T Some of the orei are also reduced by amalgamation with mercury, and the mercury expelled by heat. Properties. Silver has the clearest white color of all the metals. Its lustre, when polished, is surpassed only by pol- ished steel ; so malleable that it may be extended into leaves less than a ten thousandth of an inch in thickness, and so ductile that it may be drawn into wire finer than the human hair. It fuses at 1873 Fahr., and appears extremely brilliant. * Lat. argentum. t This process is conducted in the following manner : The lead is kept at a red heat, in a flat furnace, with a draught of air playing on its surface. The lead is thus rapidly oxidized, while the silver is un- affected. As fast as the oxide is formed, it melts and runs off through an aperture in the sides of the furnace; so that, in the end. the Ir.-uJ is all removed. The button of silver which remains is then melted in a small furnace resting on a porous earthen dish made with bone ashes, called a cupel, the. porosity of which is so great that it absorbs any por- tions of litharge which may remain on the silver. The ciijtrl is prepared by driving pounded bone ashes into a small brass mould by means of a pestle. It should then be removed and dried on paper. The cupel is then placed in a muffle, which is made of clay, arched above, and closed on all sides except the front. The whole is then placed in a cupelling furnace , which has an opening in one of its sides to receive the muffle. This is a very important process, and much used by re- finers and assayers, in the analysis of alloyed silver- Compounds of Silver 277 It is not oxidized by air or moisture, but is tarnished by sulphurous vapors, which act slowly upon it; it burns with a fine green light, and throws off fumes of oxide when ex- posed to the action of voltaic currents. None of the pure acids act upon it but the sulphuric and nitric; the latter is its proper solvent, with which it forms the nitrate which, after fusion, is the lunar caustic. Use. Silver is one of the precious metals, and is used as a coin, and for various purposes of art. Oxide of Silver (Ag-fO or AgO. 1 16) is best formed by mixing a solution of pure baryta with the nitrate dissolved in water ; it is of a brown color, insoluble in water, and easily reduced by a red heat. Fulminating Silver is a compound of oxide of silver and ammonia. Process. Precipitate nitrate of silver by lime water ; and, after wash- ing and drying the precipitate, put it into a vessel of pure ammonia for twelve hours; a black powder will be thrown down, which, when carefully dried, explodes violently by the gentlest heat, or by slight friction. Great care should be taken in its preparation, and it should be preserved in small quantities in paper boxes. By heating the solution, a more dangerous compound is formed. A compound similar to the above, but .less dangerous, is formed by dissolving silver in nitric acid, and adding to the solution successive portions of alcohol. This substance is used in the preparation of small balls called torpedoes. Chloride of Silver (Ag + Cl. 143.42) is the horn silver of mineralogists. Process. It is formed by mixing hydrochloric acid with a solution of oxide of silver. When first precipitated, it is white, but becomes almost black by exposure to the solar rays; insoluble in water, but very soluble in ammonia, by which it is usually distinguished from other chlorides. It is often employed in analysis as the means of ascertaining the amount of chlorine present in various compounds. Iodide of Silver (Ag-j-I- 234.3) is a greenish-yellow substance. Sulphuret of Silver. Ag -f- S. 124.1. This is the silvrr gl.anc& of mineralogists. Silver has a strong affinity for sulphur. Qn passing a current of hydrosulphuric acid gas through a solution of lunar caustic, a dark brown precipitate subsides, which is a sulphuret of silver. Cyanuret of Silver (Ag-f- Cy. 134.39) is a white, curdy substance. Alloys of Silver. Silver is alloyed with most of the metals. With steel, it forms an alloy used in cutlery ; with copper, 24 278 Metals. Gold. it forms the silver plate and coin,* which is the most useful of its alloys ; with mercury, it forms an amalgam, sometimes employed for plating copper. Thermometer scales and clock dials are usually silvered by an alloy of chloride of silver, chalk, and pearlashes. GOLD.\ Syrab. Au. Equiv. 199.2. Sp. gr. 19.257. Gold Was known to the ancients, and has always been highly valued, as the most precious of the metals. . Natural History.^ Gold occurs native, alloyed with a little silver or copper. It crystallizes in cubes and octohedra ; it is found in large quantities in alluvial soils, and in the beds of certain rivers, especially on the western coasts of Africa and Peru, in Brazil and Mexico, in Europe and the United States.f Process. Gold is generally separated by amalgamation and cupellation ; but the best mode is to fuse the gold with silver, so that the latter shall constitute J of the mass ; nitric acid will dissolve the silver, and leave the gold. This process is called quartation. To obtain gold perfectly pure, dissolve standard gold in nitrohydrochloric acid; evaporate the solution to drymv-s, re-dissolve it in distilled water, filter, and add to the solu- tion sulphate of the protoxide of iron ; a black powder falls, which, when washed in dilute hydrochloric acid and distilled water, yields, on fusion, a button of pure gold. Properties. Gold is distinguished from all other metals by its yellow color; it exceeds all others in ductility and malleability ; it may be beaten into leaves not exceeding SFsWtT f an m h m thickness ; it is very flexible and soft ; fuses at 2016 Daniell, and appears of a brilliant green color. * The standard silver of Great Britain contains 11^- of pure silver, and $. of copper ; that of the United States, 1 part by weight of copper, and 9 of silver. The dollar weighs 4124- grs., and the dime 41 grs. t Lat. aurum. t The gold from all the mines in the United States, in 1836, amounted to 467,000 dollars, 148,100 dollars of which were from North Carolina. Compounds of Gold. 279 It is not easily oxidized, even in the state of fusion ; but, on subjecting a fine wire to an electric discharge, a purple powder is produced, which is probably an oxide; it is readily dissolved by nitrohydrochloric acid. Protoxide of Gold (Au+O. 207.3) is formed by adding a cold solution of potassa to the protochloride; a precipitate falls, of a green color, which changes spontaneously into me- tallic gold and teroxide. Binoxide of Gold (Au-f-2O. 215.2) is formed by the combustion of gold. Teroxide of Gold (Au + 3O. 223.2) is the only well- known oxide of gold. Process. Dissolve 1 part of gold in the usual way, render it quite neutral by evaporation, and re-dissolve in 12 parts of water; to the solution add 1 part of the carbonate of potassa, dissolved in twice its weight of water, and digest at about 170 ; carbonic acid gradually escapes, and the hydrated teroxide, of a brownish-red color, subsides. After being well washed, it is dissolved in colorless nitric acid of sp. gr. 1.4, and the solution decomposed by admixture with water. The hydrated teroxide is thus obtained quite pure, and is rendered anhydrous by a temperature of 212 Fahr. T. Properties. The hydrate is yellow, but the anhydrous teroxide is nearly black, insoluble in water, and completely decomposed by solar light, or a red heat. With alkalies it acts the part of a weak acid, and was called by Pelletier auric acid. When the teroxide is kept in ammonia for the space of a day, a detonating compound of a deep olive color is formed. It is composed of 1 equiv. of gold, 2 of nitro- gen, 6 of hydrogen, and 3 of oxygen. The Fulminating Gold is a similar compound. Process. A-ld pure liquid ammonia to the dilute chloride. The precipitate which is formed will be re-dissolved if too much alkali is used; filter the liquid, and wash the sediment several times in warm water ; dry it by exposure to the air, and preserve it in small paper boxes. Exp. Hold, on the point of a knife, a small portion of the powder over the flame of a spirit lamp, and it will detonate violently. Exp. Place two or three grains on a sheet of copper, and explode it; it will force a hole through the copper ; a spark from the electrical machine, or from a flint, will not affect it ; but the slightest friction will cause it to explode ; hence the danger of forming it, or of putting it up in large quantities. 280 Metals. Gold. Protochloride of Gold. Au + Cl. 234.62. Tcrchloride of Gold (Au + 3Cl. 305.46) is obtained by concentrating a solution of gold, in ruby-red crystals. This is the compound from which pure gold is obtained, and also most of the preparations of gold. Krp. When a strong aqueous solution of the terchlnride is shaken with an equal volume of ether, two fluids result, the lighter of which is an ethereal solution of gold. Exp. When a piece ofcharcoal is immersed in the aqueous solution, and exposed to the solar rays, it is covered with metallic gold. />/. Ribbons are gilded by moistening them in this solution, and exposing them to a current of hydrogen gas. Exp. Add the protochloride of tin to a dilute aqueous solution of gold, and a purple-colored precipitate, the purple of Cnssius, is thrown down. On fusing this powder with sand and borax, it forms a purple enamel, which is used for giving a pink color to porcelain.* Alloys of Gold. Gold forms alloys with most of the metals. With tin it forms a whitish brittle alloy. On this account the old chemists called tin diabolus metal' lorum. With lead, it forms a very brittle alloy. Even the fumes of lead destroy the ductility of gold. With copper, it forms the alloy used for standard gold ; which is perfectly malleable and ductile, harder than pure gold, and resists wear better than any other alloy, except that of silver ; sp. gr. 17.157. The standard gold of the United States is an alloy of 1 part of an alloy of copper and silver, and 9 parts of pure gold. The British "sovereign" is 22 carats fine, that is, 22 parts of pure gold, and 2 of copper and silver. Water-Gilding. Mercury and gold combine, and form an amalgam much employed in gilding. It is applied to the surface of silver, and the mercury driven off by heat. Porcelain is gilded with gold powder, obtained by de- composing the chloride of gold ; applied with a pencil, and burnished after exposure to the heat of a porcelain fur- nace. * Iodides of gold are formed by the action of iodide of potassium on the terchloride of gold. Protiodide of gold; Au -f-I. 325.5. Teriodide of gold; Au -f 31. 578.1. Tersutphuret of gold ; Au -f- 3S. 247.5. Platinum. 281 PLATINUM. Symb. PI. Equiv. 98.8. Sp. gr. 21.25. Platinum is a very rare metal. It occurs native in Brazil, Peru, and other countries of South America, in rounded or flattened grains, mingled with other metals. It is found in larger quantities in the Ural Mountains. Properties. Platinum is the most dense of the metals, of a white color, resembling silver. It is malleable, and so duc- tile that it may be drawn into wire not exceeding -j-g 2 ^ of an inch in diameter. It is soft, and easily welded, conduct- ing caloric with less facility than many other metals. It is not attacked by any of the pure acids. Its solvent is chlo- rine, or nitrohydrochloric acid. It is fused before the com- pound blowpipe, and by voltaic electricity. Spongy Platinum* has the remarkable property of causing oxygen and hydrogen gases to combine. Platinum foil will produce similar effects. This is due to the attraction of the gases for the platinum, and the repulsive power of the gases themselves. They are thus so condensed upon the surface as to bring the particles of the gases within the sphere of each other's attraction. Erp. Let a jot of hydrogen and oxygen upon a piece of spongy platinum ; the gas will soon be inflamed. Protoxide of Platinum (PI -|- O. lOG.d) is prepared by digesting pro- tochloride of platinum in a solution of pure potassa. Biiwxide of Platinum (PI -f2O or P1O 2 . 114.8) is prepared with diffi- culty. According to Berzelins, it should be prepared by exactly de- composing sulphate of binoxide of platinum with nitrate of baryta, and adding pure soda to the filtered solution, so as to precipitate about half of the oxide, which falls as a bulky hydrate, of a yellowish-brown color. Sesquioxide of Platinum. 2P1-J-3O. 221.6. This oxide, of a gray color, is prepared by heating fulminating platinum with nitrous acid. Protocfdoride of Platinum (P1+C1. 134.22) is formed when the bichloride is heated to 450; half of its chloride is expelled, and the protochloride, of a greenish-gray color, remains. Bichloride of Platinum. PI -f 2C1. 169.64. This chloride is obtained by evaporating the solution of platinum in nitrohydrochloric acid to dryness, at a very gentle heat, when it remains as a red hydrate, which becomes brown when its water is expelled. (See Turner, page 408.) * The sponge is prepared by adding ammonia to a solution of the chloride, and heating the precipitate to drive off the ammonia and chlorine. 24* 282 % Metals. Platinum. Protiodide uf Platinum. PI -j- I. 225.1. Biniodidt of Platinum (PI -f- 21. 351.4) is prepared by the action of iodide of potassium on a rather dilute solution of bichloride of platinum. It is a black powder, tasteless, inodorous, and insoluble in water. Protosnlphuret of Platinum (PI + S. 114.9) is prepared by heating the ammoniacal chloride with half its weight of sulphur, until all the sal-ammoniac and excess of sulphur are expelled. Bisulphurct of Platinum (Pl-f-2S. 131) is prepared by dropping a solution of bichloride of platinum into a solution of sulpnuret of po- tassium. fulminating Platinum may be prepared by the action of ammonia in excess on the sulphate of protoxide of platinum. It explodes at 420 with a very loud report, but does not explode by percussion. Palladium, Rhodium, Osmium, and Iridium, are found associated with platinum, but exist in small quantities. Palladium (Pd. 53.3. Sp. gr. 11.5) was discovered by Wollaston, and resembles platinum in color and lustre. Rhodium (R. 52.2. Sp. gr. 11) was also discovered by Wollaston. It is, when fused, of a white color, hard, and extremely brittle. It attracts oxygen at a red heat, and a mixture of peroxide and protoxide of rhodium is formed, not acted upon by any of the acids, unless. alloyed with other metals. Osmium (Os. 99.7. Sp. gr. 7 to 10) was discovered by Tennant, in 1803. It is a black powder, which acquires metallic lustre by friction. When heated in the open air, it takes fire, and is readily oxidized and dissolved by fuming nitric acid. Osmic Acid (Os-j-4O. 137.7) is formed by the oxidation of osmium by acids, by combustion, or by fusion with nitre or alkalies. Its vapor is very acrid, exciting cough, irritating the eyes, and producing a copious flow of saliva.* Iridium (Ir. 98.8. Sp. gr. 15.3629) was discovered by Tennant, in 1803, and about the same time by Descotils, of France. It is the most infusible of all metals, very brittle, and when polished resembles platinum.t * For other compounds of osmium, see Turner, 5th ed. p. 412. t Iridium forms with oxygen four < chlorides. (See Turner, 5th ed. p. 414. t Iridium forms with oxygen four oxides, and with chlorine four "thed. Salts. 283 Latanium (La) is a metal recently discovered by Mosander. It is prepared by calcining the nitrate of cerium, mixed with nitrate of latanium. CHAPTER III. CLASS III. SALTS, OR SECONDARY COMPOUNDS. Salts comprise a very extensive class of compounds, in which acids combine with oxides, or with other compounds having similar properties. The oxide which combines with the acid, is termed a base, or salifiable base. The substances hitherto described are either simple bodies, or, with a few exceptions, compounds of two simple elements, and are hence called binary compounds. Salts, on the other hand, are composed of three or more simple bodies, and are hence termed secondary compounds. As salts, under favorable circumstances, readily assume regu- lar crystalline forms, it seems proper, before proceeding to describe them, to present the subject of crystallization in general. SECTION 1. CRYSTALLIZATION. Most bodies, under favorable circumstances, may be made to assume the form of a regular geometrical solid. The process by which such a body is produced is called crystal- lization ; the solid is termed a crystal; and the science, the object of which is to study the form of crystals, is crystal- ography. The condition, by which this process is peculiarly favored, is the slow and gradual change of a fluid into a solid, the arrangement of the particles being at the same time undisturbed by motion. This is exemplified during the slow cooling of a fused mass of sulphur or bismuth, or the spon- 284 Salts. Crystalography. taneous evaporation of a saline solution. The numerous crys- tals found in the mineral kingdom are due to the same cause. The surfaces which limit the figure of crystals are called planes or faces. The lines formed by the junction of two planes are called edges, and the angle formed by two such edges is a. plane angle; a solid angle is the point formed by the meeting of at least three planes. T. The forms of crystals are exceedingly diversified; they may be divided into primary and secondary forms. The primary forms are fifteen in number, and may be distributed as follows : 1. Prisms ; 2. Octohedrons; 3. Do- decahedrons. I. The prisms have either a six-sided base, or nfo base. (1.) Right Prisms. The bases are either right * or oblique, and the prisms are named according to their bases. 1. The Hexahedron, or Cube, (Fig. 89,) is a figure bounded by six square faces, and all the angles of its edges are equal to 90 degrees. 2. The Right Square Prism (Fig. 90) differs from the cube in having its four lat- eral planes c, c, c, c, rectangles, and the ter- minal planes a a squares. 3. The Right Rectangular Prism (Fig. 90) differs from the former in having the terminal planes a, a, rectangular instead of square. 4. The Right Rhombic Prism (Fig. 91) differs from the two preceding only in its terminal planes a, b t being rhombs. 5. The Right Rhom- boidal Prism (Fig. 92) Fig. 89. Fig. 90. Fig. 91, Fig. 92. * The term right denotes that the lateral and terminal planes are inclined to each other at a right angle. It is used in opposition to Crystalography . 285 96. differs from the preceding form in the terminal planes cc being rhomboids. 6. The Regular Hexagonal Prism (Fig. 93) is bounded by six perpendicu- lar or lateral planes, and two horizontal or terminal planes, a, t, which are at right angles to them. (-2.) Oblique Prisms. 7. The Rhombohcdron -,. Oj< -,. (Fig. 94) is bounded by ' S ' 4 ' F ' S> six rhombic faces, of the same size and form. ' 8. The Oblique Rhombic Prisms (Fig. 95) have the terminal planes ,, rhombs, with the lateral planes forming oblique angles with them. 9. Oblique Rectangular Prism differs from the preceding in having the terminal planes rectangles. 10. Oblique Rhomboidal Prism (Fig. 96) differs from the two preceding forms in the terminal planes a, a, being rhom- boids. 11. The Octahedrons are also named from their bases. The base of the octohedron is a section passing through four angles. 11. Regular Octohe- dron (Fig. 97) has a Fig. 97. square base, a a a a, and is contained under eight equilateral triangles hence all its plane an- gles are equal to 60 de- grees. This figure is a regular solid of geom- etry. 12. Square Octohe- dron (Fig. 98) has a square base, aaaa, and is bounded by eight faces, which are isosceles triangles. * The base is always a square, the only part of the figure which is constant. oblique, which signifies that the sides are not perpendicular, but form an oblique angle with the terminal planes. T. 286 Crystalography. 13. Rectangular Octahedron (Fig. 99) has a rectangular base, aaaa, and is bounded by eight isosceles triangles, four of which are different from the other four. 14. Rhombic Octohcdron (Fig. 100) has a rhombic base, aaaa, and is con- tained under eight similar scalene trian- gles, but all its dimensions are variable. III. Dodecaliedrons. 15. There is but one pri- mary dodecahedron, called the rhombic dodecahedron, (Fig. J01,) and is limited by twelve similar rhombic faces; the faces incline to each other at an angle of 120 degrees . 99. Fig. 101. Secondary Forms. The secondary forms of crystals are, very numerous, amounting to millions. The forms of a single mineral calca- reous spar have been found to be nearly a thousand ; but each of the secondary forms may be reduced to one or more of the primary, by a process called cleavage. This proc< b usually performed with a sharp instrument, by removing thin laminae from the faces, edges, or angles of the crystal. The surfaces exposed by splitting or cleaving a crystal, are termed the faces of cleavage, and the direction in which it may be cleaved is called the direction of cleavage. Some crystals are cleavable in one direction, and some in two, three, four, or more directions. Those which cleave in more than two directions may, by the removal of layers parallel to the planes in their cleavage, * The instrument used for measuring the angles, at which the planes of crystals meet, or incline to each other, are called goniometers. See Dana's Mineralogy, p. 32, New Haven. 1837. Oxy-Salts. 287 be made to assume regular primary forms, whatever be their figure previous to cleavage. It was formerly supposed that each substance always had the same primary form ; but the discovery was made by Mitscherlich, in 1819, that identity of composition did not always indicate identity of crystalline form. To this new branch of science the term isomorphism (from /aoc, equal, and /JO^T), form) is applied.* The phenomena of crystallization are ascribed to cohesive attraction, or, more properly, to crystalogenic attraction. The crystallization of salts is most readily effected by dis- solving them in water, and evaporating the solution. Exp. Introduce into a large matrass a pound and a half of Glauber a salts, (sulphate of soda,) with a pound of water, and boil the mixture until all the salt is dissolved ; cork it tight, as the heat is removed, and let it cool. On taking out the stopper, the salt will suddenly crystal- lize, and the whole will become nearly solid. The water enters into the crystal in definite proportions, and is called the water of crystallization. The quantity of combined water is very variable in different crystals; such salts, when heated, dissolve, if soluble, in their own water of crystallization, undergoing what is termed watery fusion : some salts, when exposed to the air, lose their water of crys- tallization, and crumble down into a fine powder ; this is termed efflorescence: others absorb water from the atmos- phere, and are said to deliquesce. Some salts enclose mechanically within their texture parti- cles of water, by the expansion of which, when heated, they burst with a crackling noise ; this is called decrepitation. The salts are divided into four orders : SECTION 2. ORDER I. GXY-SALTS. This order includes no compound the acid or base of which does not contain oxygen. All the powerful alkaline * * See Turner, 5th ed. p. 429. 288 Salts. Sulphates. bases, except ammonia, are protoxides of an electro-positive metal. If M represent an equivalent of any metal, M-|-O or MO is the strongest alkaline base, and generally the only one which the metal is capable of forming; a single equiv. of acid neutralizes MO, forming a neutral salt. Thus, if an equiv. of sulphuric and nitric acids be represented by SO 3 and NO 5 , all the neutral sulphates and nitrates of the protoxide will be indicated by MO -fr SO 3 and MO + NO 5 ; hence it may be inferred, that, in each family of salts, there is a constant ratio in the oxygen of the base and that of the acid; that for sulphates is as 1 to 3, and the nitrite- as 1 to 5. If the base be a binoxide, the same relation is preserved. Saks sometimes combine with each other, forming double salts ; these are composed of two acids and one base, of two bases and one acid, or of two different acids and two differ- ent bases ; these were formerly called triple salt*. Those salts which are formed by the same acid, combined with different bases, have many properties in common, and hence they are classed in the same family. ^. SULPHATES. Many of the sulphates occur native; of which, those of lime and baryta are the most abundant. They may all be formed by the action of sulphuric acid on the metals, their oxides, their carbonates, or by double decomposition. They vary in solubility in water, and are all decomposed at a white heat, and by carbonaceous matter with the aid of heat. Sulphuric Acid, which is the acid of all the sulphates, is readily detected by the chloride of barium the acid having a stronger affinity for baryta than for any other alkaline base. The sulphates are a very numerous family of salts. The following are the most important : Sulphate of Potassa, (KO -f- SO 3 . 87.25,) yotassa sulphas, Sulphates. Potassa. Soda. 289 was formerly called sal de duobus. It may be prepared by neutralizing carbonate of potassa with sulphuric acid. Properties. Taste saline and bitter. Its crystals belong to the right prismatic system, and contain no water; soluble in 16 times their weight of water at 60, and in 5 of boiling water. Bisulphate of Potassa. KO-f 2SO 3 . 127.35; with 1 equiv. of water, 136.35. This salt is prepared by heating the sulphate, with half its weight of sulphuric acid, in a platinum crucible. Properties. It has a sour taste, and reddens litmus paper;* is more soluble than the sulphates, and its crystals belong to the same order. It is used for cleaning coin, and other works in metal. Sulphate of Soda (NaO + SO 3 . 71.4; in crystals, with 10 equiv. of water, 161.4) is well known as Glauber's salts. It is found in the earth, and in the water of many springs. It is easily formed by saturating SO 3 with carbonate of soda. Properties. Taste bitter, cooling, and saline. Its crys- tals belong to the right prismatic system; effloresces on exposure to the air, and undergoes watery fusion when heated. 12. parts of the salt require 100 of water at 32 to dissolve them. Used in pharmacy, and in the manufac- ture of glass. Bisulpkate of Soda. NaO-f-SSO 3 . 111.5; with 4 equiv. of water, 147.5. Suipltate of Litha (LO-f-SO 3 . 58.1; in crystals, with 1 equiv. of water, 67.1) has a saline taste, very soluble and fusible, and crystal- lizes in flat prisms. Sulphate of Ammonia (H 3 N -f- SO 3 . 57.25 ; in crystals, with 1 equiv. of water, 67.1) sometimes occurs native in volcanoes, and near cer- tain small lakes in Tuscany. It may be prepared by neutralizing sulphuric acid with carbonate of ammonia. It is contained in soot from coal. Properties. It crystallizes in long, flattened, six-sided prisms, soluble in 2 parts of water at 60, and in an equal weight of boiling water; effloresces in warm, dry air, losing * Unglazed paper, moistened in an infusion of litmus, and dried. 290 Salts. Sulph ates. 1 eqniv. of water; yields its water of crystallization by heat, fuses, and is decomposed, yielding nitrogen, water, and sulphate of ammonia. Uses. It is the source of the hydrochlorate of ammonia, which is obtained by a mixture of common salt and sulphate of ammonia by sublimation. Sulphate of Baryta (BaO + SO 3 . 116.8. Sp. gr. 4.4) occurs native in great abundance, and is known by the name of heavy-spar. Properties. Insoluble in water, and is precipitated by adding sulphuric acid to any soluble salt of baryta. So delicate is baryta as .a test of SO 3 , that 1 part of sulphate of soda in 400,000 .of water is detected by it. It fuses at a high temperature into an opaque, white enamel. Uses. It is employed in the manufacture of jasper irare, and for a paint under the name of permanent white.* (See Baryta, page 227.) Sulphate of Strontia (SrO + SO 3 . 91.9) occurs native in beautiful crystals in Sicily, and also on Strontian Island, Lake Erie. Properties. It has a blue tint, and is called celestine; sometimes it is colorless and transparent ; nearly insoluble, requiring 4000 parts of cold, and 3840 of hot water to dissolve it. Heated with charcoal, its acid is decomposed, and sulphuret of strontium is formed. Sulphate of Lime (CaO + SO 3 . 68.6; with 2 equiv. of water, 86.6) occurs in nature in large quantities. Every 'variety of gypsum is the sulphate combined with 2 equiv. of water; such as plaster of Paris, selenite, which is a crystallized variety, alabaster, a white, compact varie- ty, used in statuary, and anhydrite t which contains no water. The salt may be formed by mixing, in solution, a salt r of lime with any soluble sulphate. Properties. Crystals of anhydrite belong to the right, and of gypsum to the oblique prismatic systems. It is nearly tasteless, soluble in 500 parts of cold, and 450 of boiling * It is the best paint for marking phials and jars in the laboratory. It may be prepared by mixing the powder with oil and lampblack. Sulphates. ^ 291 water ; hence it is generally found in spring and river w ater, and especially in those waters called hard. Baryta will de- tect the sulphuric acid, and oxalic acid the lime. Heated to 212 in vacua, it parts with 1 equiv. of water, and at 300 the whole ; in this state it is used as a cement. By mixing it with a certain portion of water, it hardens rapidly, and be- comes dry and so^id ; on this account it is much used for taking impressions, for stereotype plates, and for casts, busts, and a great variety of purposes in the arts. It is used in agriculture as a mineral manure, and is highly useful to most soils. Sulphate of Magnesia (MgO-\-SO*HO. 69.8; in crystals, with (5 equiv. of water, = 123.8) was procured from the springs of Epsom, England, and hence called Epsom salt. It is found native, and constitutes the bitter salt and hair salt of mineralogists. Sometimes it is found incrusting the damp walls of cellars and new buildings. Many saline springs contain it. Process. But it is generally obtained from sea-water, and exists in the bittern which is left after the crystallization of common salt. It is obtained by decomposing the hydro- chlorate of magnesia contained in it with SO 3 . It may also be formed from the carbonate by adding sulphuric acid. Properties. It has a saline, bitter, and nauseous taste. Its crystals are small, quadrangular prisms,* slightly efflores- cent in dry air, soluble in an equal weight of water at 60, and of their weight of boiling water. They undergo watery fusion when heated, and are partially decomposed at a white heat. Sulphate of Alumina. 2AlO 3 -f-SO 3 . 91.5 j in crystals, with 9 equiv. of water, 172.5 Tersulphate of Alumina. 2A1O 1 -f 3SO 3 . 171.7; in crystals, with 18 equiv. of water, 333.7. The Hi/drated Disulphate is calted Mumlnite. Sulphate of Protoxide of Manganese. MnO -{- SO 3 IIO. 84.8. Sulphate of Protoxide of Iron. FeO + SO 3 HO. 85.1 ; in crystals, with 5 equiv. of water, eq. 130.1. This is known * The larger crystals are generally right rhombic prisms. 292 Salts. Sulphates. by the name of green vitriol, or copperas. It is prepared on a large scale for the arts, by exposing the native protosulphu- ret of iron to air and moisture ; the iron is converted into an oxide, and the sulphur into SO 3 ; they then combine and form the sulphate. It may also be formed by the action of SO 3 on the iron. Properties. Its taste is strongly styptic and inky. When pure, it does not redden the vegetable blue colors. Its crys- tals have a blue tint, and belong to the oblique prismatic system ; soluble in 2 parts of cold, and in its weight of boiling water. It is used in the manufacture of fuming sul- phuric acid and in dyeing. Tersulphate of the. Seyuioxide. Fe^ 3 + 3SQ3. 200.3. Disulphate of the Sequioxidc. 2Fe 2 O 3 + SO*. 200.1. Sulphate of the Protoxide of Zinc, (ZnO + SC^HO. 89.4 ; with 6 equiv. of water =. 143.4,) commonly called white vitriol, is formed by the action of dilute sulphuric acid on zinc. It is prepared in the arts by roasting the native sulphuret of zinc. Properties. It crystallizes, by spontaneous evaporation, in transparent, flattened, four-sided prisms, referable to a rii/ht rhombic prism, and isomorphous with Epsom salt. Taste strongly styptic, and, although a neutral salt, reddens vegeta- ble blue colors; soluble in 2| parts of cold, and a less quan- tity of boiling water. Use. A powerful emetic, and poisonous if given in large doses. Sulphate of Protoxide of Nickel (NiO + SO 3 HO. 86.6) crystallizes from its solution in pure water, in right rhombic prisms, and, like most of the salts of nickel, is of a green color. Sulphate of Protoxide of Cobalt (CO + SO 3 HO. 86.6) is formed by digesting dilute SO 3 with oxide of cobalt. On evaporation, it appears in the form of red crystals. Tersulphate of the- Sequioxide of Chromium. Cr 2 O 3 4- 3 SO 3 . 200.3. Sulphates. 293 Sulphates of the Oxide of Copper. The Disulphate (2CuO -f SO 3 . 1 19.3) has not been ob- tained in a separate state. The Sulphate, or Blue Vitriol* (CuO + SO 3 HO. 88.7 ; in crystals, with 4 equiv. of water, 124.7) is formed by roasting the native sulphuret, or by dissolving the protoxide in dilute sulphuric acid, and crystallizing by evaporation. Properties. The crystals are of a blue color, and yield 4 cquiv. of writer at 212, and the whole at 430 Fahr., when it becomes a white powder. When ammonia is dropped into a solution of the sulphate, it forms a dark blue solution, from which, when concentrated, crystals are deposited by the addition of alcohol. This is the ammoniarit of copper of the U. S. Phar. Sulphate of the Oxides of Mercury. The Sulphate of Protoxide (HgO+ SO 3 . 250.1) is formed when '2 p irts of mercury are heated with 3 of strong sul- phuric acid, so as to produce effervescence. If a strong heat is employed, the Bisulphate (HgO 2 -f2SO 2 . 298.2) results, both being an- hydrous. When this bisulphate (the salt employed for making corrosive sublimate) is thrown into hot water, a yel- >\v salt, the Sitbtulphate, (4HgO 2 + 3SO 3 . 992.3,) called turpeth min- eral, is generated. Sulphate of Oxide of Silver (AgO + SO 3 . 156.1) is depos- ited when sulphate of soda is mixed with nitrate of silver, and also by boiling silver with its weight of sulphuric acid. Properties. It is white, and easily fused ; soluble in 80 times its weight of hot water, and deposits small, needle- shaped crystals on cooling. It forms with ammonia a double salt, consisting of 1 equiv. of oxide of silver, 1 of acid, and 2 of ammonia. It crystallizes in rectangular prisms, isomorphous with the double chromate and seleniate of oxide of silver and ammonia. * Great use is now made of this substance for exciting electricity in galvanic batteries. 25* 294 Salts. Sulphates. Nitrosulphuric Acid, consisting of 1 part of nitric dis- solved in 10 of sulphuric acid, dissolves silver, but scarcely acts upon copper, lead, or iron, unless diluted with water ; hence its use in separating silver from old plated articles. Double Sulphates. Sulphate of Soda and Liw (NaOSO 3 + CaOSO 3 . 140) is the Glnuber- ite of mineralogists, and occurs in the salt-mines of New Castle. Sulphate of Putassa and Magnesia (KOSCH + MgOSO 3 ) is formed by mixing solutions of the two salts. Sulphate of Potassa and Alumina. KOSO3 + Al^K) 3 . 3SO 3 . 258.95, do. with 24 equiv. of water = 474.95. This salt, the common alum, is prepared by roasting and lixiviating cer- tain clays, containing iron pyrites, and adding to the lyes a quantity of sulphate of-potassa. It is obtained in Italy from alum-stone. Alum is also found in volcanic countries, pro- duced by the action of sulphurous vapors on rocks com urnm: feldspar. Properties. It has a sweetish, astringent taste ; is soluble in 5 parts of water at 60, and crystallizes in octohedr<:i- Ignited with charcoal, it forms Homberg's Pyrophorus. Exp. Take 3 parts of lampblack. 4 of calcined alum, and 8 of jx-arl- afches; mix them thoroughly, and heat them inan iron tube to a bright cherry-red, for one hour; on removal from the fire, the tube must be carefully breathed upon, ignites with slight explosions. The essential part is stopped. This substance, when exposed to the air and upon, ignites with slight explosions. Tin probably sulphurct of potassium^ in minute divisions. Use. Alum is of great use in the arts, especially in dye- ing and calico-printing, because of its attraction for coloring matter. Ammonia Alum has the same form, appearance, and taste. Soda Alum is also similar, except that it contains 26 equiv. of water. Iron Alum is formed by mixing sulphate of potassa with tersulphate of sesquioxide of iron; it resembles common alum in form, color, taste, and composition. Chrome Alums. The tersulphate of sesquioxide of chro- mium forms double salts, with the sulphate of potassa and ammonia, very similar to the preceding. Sulphites Nitrates. 295 Manganese Alum is formed by mixing a solution of ter- sulphate of sesquioxide of manganese with sulphate of po- tassa. These salts all crystallize in the octohedral system, and are similar in composition, one oxide being substituted for another, to form the different varieties. 2. SULPHITES. The salts of sulphurous acid have not hitherto been mi- nutely examined ; the sulphites of potassa, soda, and ammo- nia, are made by neutralizing those alkalies with sulphurous acid, and are soluble in water ; but most sulphites are spar- ingly soluble, if at all ; they are decomposed by the stronger acids. (See Turner, 5th edit. p. 443.) 3. NITRATES. The nitrates may be prepared by the action of nitric acid on metals, on the salifiable bases, or on carbonates,, As nitric acid forms soluble salts with all alkaline bases, the acids of the nitrates cannot be precipitated by any re- agent. T. The nitrates are all decomposed by a high temperature, and by the agency of heat and combustible matter ; hence they are much employed as oxidizing agents. The process of oxidation by nitre, is called deflagration, which is gener- ally performed by mixing the inflammable body with an equal weight of the nitrate, and projecting the mixture, in small portions, into a red-hot crucible. All the neutral nitrates of the fixed alkalies and alkaline earths, together with most of the neutral nitrates of the common metals, are composed of 1 equiv. of nitric acid, and 1 of the protoxide ; hence the oxygen of the base is to that of the acid, as 1 to 5 ; the general formula is MO -|- NO 5 . Nitrate of Potassa (KO-j-NO 5 . 101.3) is an abundant natural product; it is obtained from the East Indies by lixiviating certain soils ; in Germany and in France, it is pro- duced in what are termed nitre-beds. 206 Salts. Nitrates. The French process consists in lixiviating old plaster rub- bish. Nitre also exudes from new walls. Some caverns in Kentucky afford nitrate of lime, from which nitre is obtained by adding carbonate of potassa ; it is also found under old buildings, and is commonly called nitre and saltpetre. Properties. Colorless ; has a saline and cooling taste ; soluble in its own weight of boiling water ; crystallizes in six-sided prisms without any water of crystallization ; and fuses at ivory has acquired a bright yellow stain ; remove it to a tumbler of dis- tilled water, and expose it to the direct rays of the sun for two hours, * One of the best solvents of silver may be formed by dissolving 1 part of nitre in 10 by weight of concentrated sulphuric acid. When this compound is heated to between 100 and 200 F.-ilir., it will dis- solve about one sixth of its weight of silver without acting in the least upon any copper, gold, lead, or iron, with which the silver may he combined ; hence it is very useful to detach silver from old plate. To recover the silver from the solution, add common salt, and then de- compose the chloride thus formed by carbonate of soda. Nitrates Chlorates. 299 when it will become black, but, on rubbing it, the surface will become bright, resembling pure silver. Nitrate of Silver is the principal ingredient in indelible ink, and in those compounds which are used for changing the color of the hair. In all these cases, the effect depends upon the reduction of a part of the silver to the metallic state. 4. NITRITES. According to Turner, very little is known of these salts. 5. CHLORATES. The salts of chloric acid are very analogous to those of nitric acid. They are all soluble in water, and are dis- tinguished by the action of strong hydrochloric and sulphuric acids, the former disengaging chlorine, and protoxide of chlo- rine, and the latter chlorous acid. The chlorates are mostly composed of 1 equiv. of protoxide and 1 of acid ; hence the oxygen of the base is to that of the acid, as 1 to 5, or Mo-)- CIO 5 . None of the chlorates are found native, and those of baryta and potassa are the only ones which require particular notice. Chlorate of Potassa (KO -f CIO 5 . 122.57) may be formed by transmitting chlorine gas through a concentrated solution of pure potassa, until the alkali is completely neutralized ; the results are chloride of potassium and chlorate of potassa.* Properties. Chlorate of potassa generally occurs in four and six-sided crystalline scales; colorless, and of a pearly lustre ; soluble in 16 times its weight of water at 60, and in 2J of boiling water. It is anhydrous, and fuses at 400 or 500 ; by increase of temperature, it yields pure oxygen gas. It acts very energetically upon many imflammable bodies. Exp. Put 2 grains of the salt into a mortar, with 1 grain of sulphur. Mix them accurately, and then strike the collected mass * For other processes, see Turner's Chemistry. 300 Salts. Chlorates. forcibly with the pestle ; a loud detonation will ensue. Charcoal will produce a similar effect; or, Ezp. Instead of the sulphur, add a grain of phosphorus, and the detonation will be much louder.* Many of the stronger acids decompose this salt. Exp. Mix 2 parts of sugar with 1 of chlorate of potassa, and pour upon it a few drops of sulphuric acid ; the decomposition will be at- tended by a sudden inflammation. Exp. Put 2 parts of this salt with I of phosphorus into a wine- glass filled with warm water, and then pour, by means of the dropping- tube, strong sulphuric or nitric acids directly upon the salt; the phos- phorus will ignite under the water, owing to the development of oxy- gen from the decomposition of the salt. Uses. It is employed in the preparation of percussion powder, in which this salt is substituted for nitre. Matches are also made by first dipping them in melted sul- phur, and then in a composition of chlorate of potassa, sugar, gum arabic, and vermilion. Lucifer Matches have a similar composition. An attempt was made in 1788 to substitute chlorate of potassa for nitre, in the manufacture of gunpowder; but, as might have been expected, on triturating the mixture, it exploded with violence, and destroyed several of the operators. A few grains of this salt, put into water with a few drops of hydrochloric acid, form a convenient bleach in ir liquor. Chlorate of Baryta (BaO + CIO 5 . 152.12) is prepared by digesting for a few minutes a concentrated solution of rhlora of potassa, with a slight excess of silicated hydrofluoric acid ; the alkali is precipitated in the form of an insoluble, double hydrofluate of silica and potassa, while chloric acid remain-* in the solution. The liquid, after filtration, is neutralized by carbonate of baryta, which throws down the excess of silicated hydrofluoric acid, and chlorate of baryta remains in solution. Properties. It yields, on evaporation, crystals in the form of four-sided prisms, has a pungent taste, is soluble in 4 times its weight of cold, and in a smaller quantity of warm water. It is employed for forming chlorous acid. * The hands should be covered with gloves, and the mortar turned from the face. Per chlorate* lodates. 301 6. PERCHLORATES. The neutral protosalts of perchloric acid consist of 1 equiv. of acid and base, as is expressed by the formula MO -(-CIO 7 . Most of the salts are deliquescent, very solu- ble in water, and soluble in alcohol. When heated to red- ness, they yield oxygen gas and metallic chlorides ; and they are distinguished from the chlorates by not acquiring a yellow tint, on the addition of hydrochloric acid. T. The salts are formed by neutralizing the base with per- chloric acid, excepting perchlorate of potassa, which is formed from the chlorate by heat and sulphuric acid. 7. CHLORITES. The alkaline chlorites are formed by transmitting a current of chlorous acid gas into a solution of the pure alkalies ; they are remarkable for their bleaching and oxidizing properties. 8. HYPOCHLORITES. These salts may be formed by the action of chlorine gas on the alkaline bases ; the most important of these is the hypo- chlorite of lime, which is well known as a bleaching powder. 9. lODATES. The salts of iodic acid are very similar in character to those of chloric acid ; in all the neutral protiodates, the oxy- gen of the base and acid is in the ratio of 1 to 5 ; the iodates are easily recognized by the action of de-oxidizing agents. Thus the sulphurous, phosphorous, hydrochloric and hydriodic acids deprive the iodic acid in the salt of its oxygen, and set the iodine at liberty. None of the iodates are found native ; they are all insoluble, or sparingly soluble in water, excepting the iodates of the alkalies. lodate of Potassa (KO + IO 5 . 213.45) may be obtained 26 302 Salts. Pltosphates. by adding iodine to a concentrated, hot solution of pure potassa, until the alkali is completely neutralized. All the insoluble iodates may be procured from this salt ; thus the iodate of baryta may be formed by mixing chloride of barium with a solution of iodate of potassa. 10. The Bromaies are very similar to the chlorates and iodates. 11. PHOSPHATES. There are three acids of phosphorus which are isomeric the phosphoric, pyrophosphoric, and mr.taphosphoric ; hence it becomes necessary to have three corresponding families of salts. I. Phosphates. All the neutral protophosphates are solu- ble in water, and redden litmus paper, on which account they are called super plwsphates. The Tripfiosphatcs, except those of the pure alkalies, are sparingly soluble, or insoluble in water, but are all dissolved by nitric or phosphoric acids. The phosphates and diphos- phates are changed by heat into pyrophosphates and meta- phosphates; the phosphates of the pure alkalies are but par- tially decomposed by heat and combustible matter, and those of baryta, strontia, and lime, undergo no change ; but most of the phosphates of the second class of metals are resolved into hosphurcts by those agents. The insoluble phosphates are decomposed when boiled with a strong solution of carbonate of potassa, or soda. Triphosphate of Potassa (3KO + P 2 O 5 . 212.85) is formed by adding caustic potassa in excess to a solution of phos- phoric acid. Diphosphate of Potassa (2KO.2HO + P 2 O 5 . 165.7J is pre- pared by neutralizing the superphosphate of lime obtained from bones, with carbonate of potassa. Phosphate of Potassa (KO.2HO + P2O 5 . 136.55) is formed by adding phosphoric acid to carbonate of potassa, until the liquid ceases to give a precipitate with chloride of barium, and then setting aside to crystallize. Phosphates. 303 Triphosphatc of Soda. 3NaO-f-P 2 O 5 . 165.3; in crystals, with 24 equiv. of water, ~3S 1.3. This salt is prepared by adding pure soda to a solution of the succeeding compound, until the liquid feels soapy to the fingers; the solution is then evaporated until a pellicle forms; on cooling, the crystals which are deposited, are quickly re-dissolved in water, and are crystallized. Properties. Triphosphate of soda crystallizes in colorless, six-sided, slender prisms, which have an alkaline taste and re- action ; soluble in five times their weight of water at 60, and in still less of hot water; the crystals undergo watery fusion at 170, but are not decomposed at a red heat. The feeblest acid deprives the salt of of its soda. Triphosphatc of Soda and Basic Water. 2NaO.HO-f- P 2 O 5 . 143 ; in crystals, with 24 equiv. of water. = 359. This salt is the most common of the phosphates, being manufac- tured on a large scale, by neutralizing, with carbonate of soda, the acid phosphate of lime, which is procured by the action of sulphuric acid on burned bones. Properties. It crystallizes in oblique rhombic prisms, hence called rhombic phosphate ; its crystals are always alka- line to test paper; effloresce in the air ; soluble in four times their weight of cold, and twice their weight of warm water. Acid Triphosphate of Soda and Basic Water (NaO.2HO -|- P-O\ 120.7 ; in crystals, with 2 eq. water, = 138.7) is com- monly called the biphosphate of soda, and may be formed by adding phosphoric acid to a solution of carbonate of soda, until it ceases to give a precipitate with chloride of barium. When the solution is concentrated, it yields two different kinds of crystals without varying its composition. Phosphate of Soda and Ammonia (NaO.H 3 N-|-P 2 O 5 . 119.85, with 10 eq. water =. 209.85) is easily prepared by mixing 1 equiv. of hydrochlorate of ammonia, and 2 equiv. of the rhombic phosphate of soda ; each being previously dissolved in a small quantity of boiling water. It is known as microcosmic salt, and is much employed as a flux in experiments with the blowpipe ; when heated, it parts with its water and ammonia. 304 Salts. Phosphates. Diphosphate of Ammonia (2H 3 N + P 2 O 5 . 105.7; in crys- tals, with 3 equiv. water, = 132.7) is prepared by adding am- monia to phosphoric acid until a precipitate is formed ; the primary form of the crystals is an oblique rhombic prism. Phosphate of Ammonia (IPN + PO 5 . 88.55; in crystals, with 3 equiv. water, =. 115.55) is formed in the same manner as the phosphate of potassa, crystallizes in octohedrons with a square base, and in right square prisms. Bone Phosphate of Lime (8CaO + 3PW. 442.2) exists in bones after calcination, and falls as a gelatinous precipitate, on pouring chloride of calcium into a solution of rhombic phosphate of soda. Triphosphatc of Lime (3CaO + paQ\ 156.9) occurs in the mineral called apatite. Diphosphate of Lime, (2CaO + P 2 *) 5 + 1 eq. basic water, = 137.4,) commonly called neutral phosphate, falls as a granu- lar precipitate, when the rhombic phosphate of soda is added, drop by drop, to chloride of calcium in excess. Phosphate of Lime (CaO + P*O 5 + 2 eq. basic water, = 117.9) is commonly called the biphosphate, from its acid re- action, and may be formed by dissolving either of the pre- ceding salts in a slight excess of phosphoric acid ; it exists in urine. Diphosphate of Magnesia. 2MgO + F J O 5 . 112.8. Triphosphate of Magnesia. 3MgO -|- P 2 O 5 . 133.5. Phosphate of Ammonia and Magnesia (2MgO -(- 2H 3 N -\- 10HO + P-O 5 . 237.1) subsides as a pulverulent, granular precipitate from neutral alkaline solutions, containing phos- phoric acid, ammonia, and magnesia; it constitutes a variety of urinary concretions.- Triphosphate of Oxide of Silver is formed when the rhombic phosphate of soda is mixed in solution with nitrate of silver ; it is a yellow powder when dry ; on exposure to light, it is speedily blackened. II. Pyrophosphates. The only salts of this family which have been studied, are those of soda and oxide of silver. They are thus constituted : Arscniatcs. 305 Dipyrophosphate of Soda. 2NaO -|- P 2 O 5 . 62.6 -f 71 .4 = 134. Dipyrophospkate in crystals, with 10 eq. water, 90 = 224. Acid Dipyrophosphate of Soda and Basic Water. NaO.HO -f- P 2 O 5 = Pijrophosphate of Soda. NaO.P 2 O 5 . 31 .3 -f 71 .4 = 1 02.7. DijHjrophosphate of Oxide of Silver. 2AgO-fP 2 O\ 232 + 71.4 = 303.4. /7^ III. Mctaphosphates. The only salts of this family yet examined are those of soda, baryta, and oxide of silver. MctapkosphJe of Soda.. NaO P'O 5 , 1 eq. Na, 31.5 + leq. P 2 O 5 , 71.4 = 102.7. M.tanhosphate of Baryta. BaO.P 2 O s , 1 eq. BaO, 767 -f 1 eq. P 2 O 3 , 71.4 148.1. MHU i,i,<>* t ,liate of Silver. AgO.P 2 O 5 , leq. AgO, 116 -f 1 eq. P ! O 5 , 71.4 = 187.4. SiLb-metiphosphate of Silver. 3AgO -f2P 2 O ft , 3 eq. AgO, 348-f2eq. 142.8 = 490.8. 12. ARSENIATES. Arsenic acid resembles the phosphoric in composition, and in many of its properties. The oxygen of the oxide and acid in their salts is as 1 to 5; salts of 2 equiv. of basic water are soluble in water, redden litmus paper, and are usually considered bisalts ; those with 1 equiv. of basic water, in which the oxygen of the base and acid is as 2 to 5, are commonly called neutral arseniates ; those without water are described as- subarscniatcs. This acid has a strong tendency to form trisalts; some of the arseniates bear a red heat without decomposition, but all are decomposed when thus heated with charcoal, metallic arsenic being set at liberty. The soluble arseniates are easily recognized by the tests for arsenic. (See p. 256.) The insoluble arseniates are tested by boiling them in a strong solution of the fixed alkaline carbonates, by which they are deprived of their acid ; the acid may then be de- tected in the usual way. The following are the principal arseniates : Triarseniate of Soda. 3NaO -f As 2 O 5 , 3 eq. NaO, 93.7 + 1 eq. As 2 5 , 115.4 = 209.3. Do. in crystals with 1 eq. water 216 = 425.3. 26* 30C Salts. Arsenites. Diarseniate of Soda and Basic Water. 2NaO + HO + AsK) 5 , eq. 187. Acid Arseniateof Soda and Basic Water. JNaO -j- 2HO -j- As'Oaq. = JC4.7. Triarseniate of Potassa. 3KO -|- AsO, 3 eq. KO, 141 .454- 1 eq. As'OS 115.4 = 256.85. Diarseniate of Potassa. SKO + AsK) 5 , 2 eq. KO, 94.3 + 1 eq. As0% 115.4 = 209.7. Arseniate. of Potassa. KO. As l O, 1 eq. KO, 47.15 + 1 eq. As'O 6 , 115.4 = 162.55. Diarseniate of Ammonia. 2H 3 N 4- AsK) 5 , 2eq. NH 3 34.3+1 eq. As'O*, 115.4 ==149.7. Arseniate of Ammonia. NH 3 , AsK) 4 , 1 eq. NH 3 , 17.554-1 eq. As'O 5 , 115.4 = 132.55. Triarseniate of Baryta. 3BaO + As'O 6 , 3 eq. BaO, 230.1 + 1 eq. As'O 4 , 115.4=345.5. Diarseniate of Baryta. 2BaO+AsO 6 , 2 eq. BaO, 153.4 + 1 eq. As0, 115.4 ==268.8 Arseniate of Byrata. BaO + As'O 5 , 1 eq. BaO, 76.7 + 1 eq. As'O 4 , 115.4 = 192.1. Triarseniate of Lime. 3CaO-hA8O*, 3 eq. CaO, 85.5 + 1 eq. 8 0>, 115.4 = 2()0.9. Diarseniate of Lime. 2CaO + AsO, 2 eq. CaO, 57 + 1 eq. As'O*, 115.4 = 172.4. Arseniate of Lime. CaO + As'O*, 1 eq. CaO, 26.5 + 1 eq. As'O 5 , 115.4 = 143.9. Triarseniate of Lead. 3PbO + As'O 4 , 3 eq. PbO, 334.8 + 1 eq. As0>, 115.4=450.2. Diarseniate of Lead. 2PbO+'A 8 > O 4 . 2 eq. PbO, 223.2+1 eq. As*0, 115.4 = 3384. Triarseniate of Ox-Silver. 2AgO + AsO*, 3 eq. AgO, 348 + 1 cq. As0, 115.4 = 463.4. 13. ARSENITES. The arsenites of potassa, soda, and ammonia, may be prepared by acting with those alkalies on arsenious acid. They are very soluble in water, and have an acid re-action. Most of the other arsenites are insoluble or sparingly solu- ble in water, but are dissolved by an excess of arsenious, nitric, and most other acids, with which their bases do not form insoluble compounds. They are all decomposed when, heated in close vessels. The soluble salts, if neutral, are characterized by forming a yellow arseniate of oxide of silver, when mixed with nitrate of silver, and a green arsenite of protoxide of copper Scheele's green with sulphate of copper. The arsenite of potassa is the active principle in Fowler's arsenical solution. Chromates Borates. 307 14. CHROMATES. The chromates may generally be known by (heir yellow or red color. They may be known chemically by the green solution of chloride of chromium, formed by boiling any chromate with hydrochloric acid mixed with alcohol. They are all decomposed by heat and combustible matter. Chromate of Potassa (KO + CrO 3 . 99.15) is formed by heating to redness- the native oxide of chromium and iron (chromate of iron) with nitrate of potassa, when chromic acid is generated, and unites with the alkali of the nitre. Properties. Taste cool, bitter, and disagreeable, soluble in boiling water, and insoluble in alcohol. Bichromate of Potassa (KO + 2CrO 3 . "151.15) is of great importance in dyeing. It is prepared by acidulating the neutral chromate with sulphuric, or, still better, with acetic acid, and allowing the solution to crystallize by spontaneous evaporation. Properties. When slowly formed, four-sided rhombic prisms are deposited, which are anhydrous, and of a rich red color ; soluble in 10 times their weight of water at 60 and the solution reddens litmus. The insoluble chromates, such as those of baryta, zinc, lead, mercury, and silver, are prepared by mixing the soluble salts of those bases with a solution of chromate of potassa. Chromate of Lead. PbO + CrO 3 . 1G3.6. This is the yellow chromate, and is extensively used as a pigment. Chromate of oxide of zinc may be used for the same purpose. 15. BORATES. The boracic is a feeble acid, and neutralizes imperfectly ; hence the borates, such as soda, potassa, and ammonia, have an alkaline re-action ; hence, also, the more powerful acids separate the alkali from boracic acid, although, at a red heat, boracic acid, owing to its fixed nature, decomposes every salt whose acid is volatile. The borates of the alkalies are solu- 308 Salts. Carbonates. ble in water, but most of the other borates are sparingly soluble ; they are not decomposed by heat, though remark- able for their fusibility. They are distinguished by the following character : By digesting any borate in an excess of strong sulphuric acid, evaporating to dryness, and boiling the residue in 'strong alcohol, the solution will burn with n green fl Biboratc of Soda, (2BO 3 -|- NaO. 191.1 ; in crystals, with 10 equiv. of water, = 101.01,) commonly called borax, oc- curs native in certain lakes in Thibet. It is imported from India under the name of lineal, which, after purification, constitutes the refined borax of commerce. Properties. It crystallizes in hexahedral prisms. w The crystals are efflorescent ; when heated, they lose their water of crystallization, fuse, and form, on cooling, a crystalline mass, called glass of borax. Borax is much used as a flux for welding iron and steel. Boracite is a biborate of magnesia. A new biborate of soda has been lately described ; better as a flux, for the use of jewellers, than the preceding. 16. '.CARBONATES. The carbonates are distinguished from all other salts, by being decomposed with effervescence, owing to the escape of carbonic acid gas, by nearly all acids. All the carbonates, except those of potassa, soda, and lithia, are decomposed by heat; and all, except those of potassa, soda, and ammonia, are of sparing solubility in pure water ; but all are soluble in excess of carbonic acid. Several of them occur native. Carbonate of Potassa (KO + CO 2 . 69.27) is procured by lixiviating the ashes of land plants, and boiling the lye a process which is performed on a large scale in Russia, and in this country" This is the impure carbonate of commerce, known by the names potash and prnr/ash, and is of great utili- ty in the arts, especially in the manufacture of soap and glass. As thus prepared, it always contains other compounds, such Carbonates. 309 as sulphate of potassa, and chloride of potassium. For chemical purposes, it is obtained by heating cream of tartar to redness, when the acid is decomposed, and a pure car- bonate of potassa mixed with charcoal remains. The char- coal is removed by solution in water, and evaporation. Properties. Taste strongly alkaline, and slightly caustic; changes the vegetable purple colors to green ; soluble in less than an equal weight of water at 60; deliquesces on ex- posure to the air; is insoluble in pure alcohol, and fuses at a full red heat, but undergoes no other change. Bicarbonate of Potassa (KO + 2CO 2 . 91.39; in crystals, with 1 equiv. water, = 100.39) is made by transmitting a current of carbonic acid gas through a solution of the car- bonate. This salt is milder than the carbonate, into which it is converted by a low red heat. It does not deliquesce on exposure, and requires four times its weight of water at 60 for solution. Carbonate of Soda (NaO + CO 2 . 53.42; in crystals, with 10 equiv. water, = 143.42) is obtained from the ashes of sea- weeds, in the same manner as carbonate of potassa. The best variety of the impure salt is the barilla, which con- sists of the semifused ashes of the salsola soda, a plant culti- vated on the Mediterranean shores of Spain. Kelp is another variety, and formed from the sea-weeds on the northern shores of Scotland. Properties. Crystallizes in rhombic prisms ; effloresces, and dissolves in its water of crystallization when heated, and becomes anhydrous by continued heat ; soluble in about 2 parts of cold, and in less than its weight of boiling water. Bicarbonate of Soda (NaO + 2CO 2 . 75.54 ; in crystals, with 1 equiv. water, = 84.54) is formed by the same process as the bicarbonate of potassa, and, like that salt, is much milder than the carbonate. Sesquicarbonate of Soda (2NaO + 3CO 2 . 4HO. 164.96) is found native in Africa, on the banks of soda lakes, and is called trona. Carbonate of Ammonia (H 3 N + CO 2 . 39.27) is obtained by mixing dry carbonic acid over mercury, with twice its volume of ammoniacal gas. It is a dry, white powder, and 31 Salts. Carbonates. has an alkaline re-actiou ; its odor is pungent, resembling ammonia. Bicarbonate of Ammonia (H 3 N.2HO + 2CO 2 . 79.39) is obtained by transmitting a current of carbonic acid gas through a solution of carbonate of ammonia, and evaporating the solution by gentle heat. It is deposited in right rhom- bic prisms ; inodorous, and nearly tasteless. Sesguicarbonate of Ammonia (2H 3 N.2HO 2 + 3CO 2 . 118.60) is prepared by heating 1 part of hydrochlorate of ammonia, mixed with 1J of carbonate of lime, carefully dried. The chloride of calcium remains in the retort, and this suit is sublimed; it is hard, compact, translucent, of a crys- talline texture, and ammoniacal odor. Carbonate of Baryta (BaO + CO 2 . 98.82) occurs native in the mineral Witherite. It may be prepared by mixing a soluble salt of baryta with any of the alkaline carbonates. Properties. This salt is anhydrous, very insoluble, and highly poisonous. Carbonate of Strontia (SrO -(- CO 2 . 73.92) is known by the name of strontianite ; it may be prepared in the same manner as carbonate of baryta ; it is soluble in excess of carbonic acid. Carbonate of Lime (Ca-)-CO 2 . 50.62) is a very abundant natural production, occurring under a great variety of forms, such as limestone, marble, chalk, Iceland spar, etc.; often in regular crystals. Carbonic acid and lime have a strong affinity for each other ; and hence moist lime, or lime in so- lution, when exposed to the air, absorbs the acid contained in the atmosphere, and carbonate of lime is formed. It is sparingly soluble in water, but soluble in excess of carbonic acid; the crust formed on the top of lime water is car- bonate of lime. Carbonate of Magnesia (MgO + CO 2 . 42.82; in crystals, with 3 equiv. of water, ^r 69.82) is found native in the mine- ral called magnesite, which is nearly pure anhydrous car- bonate of magnesia. It is obtained in minute, transparent, Carbonates. 311 hexagonal prisms, when a solution of the bicarbonate evapo- rates slowly in an open vessel ; the crystals lose their water, and become opaque by a very gentle heat, and even in dry air, at 60. They are decomposed by water. A Carbonate of Magnesia, consisting of 4 equiv. of water, 3 of acid, and 4 of magnesia, falls as a white powder when carbonate of potassa is added to a hot solution of sulphate of magnesia; this salt is very insoluble, requiring 9000 parts of hot water for solution. Carbonate of Protoxide of Iron (FeO + CO 2 . ,58. 12) is a very abundant natural production, occurring either in masses, or in rhombohedrons. It exists also in most of the cha- lybeate mineral waters. It may be formed by mixing an alkaline carbonate with sulphate of protoxide of iron. It acts as a tonic upon the animal system. Bicarbonate of Protoxide of Copper (2CuO -f Co 2 . 101.32) is found native as a hydrate, in the mineral called malachite, of a beautiful green color. It may be obtained by precipitation from a hot solution of sulphate of protoxide of copper, by carbonate of soda or po- tassa ; this is the mineral green of painters. When the hydrate is boiled for a. long time in water, it loses both carbonic acid and combined water, and the color changes to a brown. The blue copper ore, and the blue pigment called verditer* have a similar composition. Carbonate, of Protoxide of Lead (PbO + CO 1 . 133.72) is the white lead of painters. It occurs native in white pris- matic crystals. As an article of commerce, it is prepared from the subacetate by a current of carbonic acid ; also by * Refiners' Verditer, made by silver refiners, is composed of 3 equiv. of oxide and 4 of carbonic acid. A very good verditer is formed by adding a quantity of lime to ni- trate of copper sufficient to throw down the oxide. The green precip- itate must be washed, and nearly dried upon a strainer. If it is then mixed with 10 per cent, of fresh lime, the color will become blue. It must now be dried, and is then fit for use. 312 Salts. Double Carbonates Silicates. exposing metallic lead in minute division to air and moisture, or by the action of the vapor of vinegar on thin sheets of lead. Dicarbonate of Peroxide of Mercury, 2HgO--f-CO 2 . 458.12. When a solution of the nitrate of peroxide o^ mercury is decomposed by carbonate of soda, this salt falls as an ochre-yellow precipitate. 17. DOUBLE CARBONATES^ The most remarkable of these salts is the double carbovat, of lime and magnesia, (MgO.CO^+CaO.CO 2 . 93.44,) form- ing the minerals called dolomite, bitter spar, and pearl spar. The rock called magnesian limestone is an impure variety of dolomite. Barytocalcite is a double carbonate of baryta and Ihnr. CaO.COs + BaO.CO'. 149.44. Carbonate of Soda, fused with the carbonate of bant -, strontia, or lime, in the ratio of their equiv., yields cry-i :!- line, definite compounds. In the same manner, also, sulphate of soda, heated with the above carbonates, yields double salts, which are very similar. 18. SILICATES. Silicic Acid is one of the most powerful acids. The snlis which it forms, although very numerous and important com- pounds, have not hitherto been fully investigated. The sili- cates are remarkable for their great variety of composition ; they are composed of from 1 equiv. of base and 6 of silicic acid to 1 of acid and 3 of base. Those most frequently met with are, 1. Simple Silicates, or those composed of 1 equiv. of base and 1 of silicic acid. These are a very numerous class of natural compounds, as, silicate of manganese, zinc, glucina, cerium, zirconia, iron, &c. 2. Bisilicates, in which 2 equiv. of silicic acid are com- Silicates. 313 bined with 1 of base. There are many native compounds of this order : tabular spar is a bisilicate of lime ; bottle glass is another example. 3. Trisilicates, in which 3 equiv. of silicic acid are united to 1 of base. The most important of the bisilicates is plas- tic clay, which is a trisilicate of alumina. 4. Quadrisilicates, which are principally artificial com- pounds, among which are crown glass, French window glass, flint glass, and enamel. In addition, it should be remarked, that there are a very great number of simple minerals, which are composed as above, or by the union of silicic acid with other acids and with bases. In fact, the greater portion of the crust of the globe is composed of silicates. The soils, rocks, and mountains, are but masses of silicates. The silicates are all fusible before .the compound blow- pipe, and all, except those of magnesia and alumina, in a forge fire. Those of 2 or more bases are most easily fused; and those of fusible bases are more easily melted than those whose bases are more refractory. In the separation of the metals from their ores, such mat- ters are added as will form with the. earthy parts of the ores fusible silicates. These float like glass on the surface of the reduced metal, and are easily removed. All kinds of glass are formed by heating siliceous sand with alkaline carbonates. When heat is applied, the alkali melts, anil the sand (silicic acid) combines with the alkali, while the carbonic acid escapes in the form of a gas, causing the mass to swell to twice its former bulk. When the car- bonic acid all escapes, the mass subsides, and is called frit. This is then put into a refractory vessel, and placed in a furnace, where it is heated until it is melted and becomes glass. (See page 213.) The silicates are all insoluble, excepting those of potassa and soda. Those compounds formed by the union of 1 or 2 equiv. of silicic acid are more soluble than those of 3 or 4. The double silicates of these alkalies, that is, the union 24 314 Salts. Hydro-Salts. of another acid or base, renders the compounds still less soluble. The silicate of alumina and soda, which is combined with sulphuret of sodium in lapis lazuli, is used by painters, under the name of ultramarine, and is a very important compound The silicates are the most ^important chemical com pounds ; forming, as they do, almost the entire mass of the soil in every country, their influence upon vegetation is con- stant and universal. To the agriculturist they are com- pounds of great interest, and should be made the subjects of intense study. SECTION 3. ORDER II. HYDRO-SALTS. This order includes those salts the acid or base of which contains hydrogen. The salts formerly called muriates or hydrochlorates of metallic oxides, are now generally de- scribed as chlorides of those metals, and also the salts of hydriodic and most other hydracids. The only salts whirh are included in this order are formed by the hydracids with ammonia and phosphurrtcd hydrogen. Hydrochlorate of Ammonia. IPN + HCL. 53.57. This is the sal ammoniac of commerce, and was formerly imported from Egypt, where it was prepared from the soot of camels' dung by sublimation ; but it is now formed by several pro- cesses. The most usual is to decompose the sulphate of am- monia* by the chloride of sodium or magnesium. It occurs native, in masses and in crystals, in the vicinity of volcanoes. Process. It may be produced directly, by introducing liquid ammonia into one retort, (see Fig. 54, p. 113,) and HCL into the other, and apply heat. As the two gases pass * This sulphate is obtained by digesting with gypsum the impure carbonate of ammonia, procured from the destructive distillation of bones and other animal substances, so as to form an insoluble carbonate of lime and a soluble sulphate of ammonia. Hydro-Salts. 315 into the receiver, a white cloud appears, which is hydrochlo- rate of ammonia in fine powder. Properties. This salt has a pungent, saline taste, and is insoluble in water and in alcohol ; it sublimes at a tempera- ture below that of ignition, without fusion or decomposi- tion. Uses. Used in the arts for a variety of purposes, in tin- ning copper, to prevent oxidation, and by dyers. When dissolved in nitric acid, it forms the aqua regia, which is employed for dissolving gold, instead of nitro- hydrochloric acid. Hijdriodate of Ammonia (H 3 N.HI. 144.45) is a white powder, very soluble and deliquescent. Hydrobromate of Ammonia (FPN.HBr. 96.55) is a white anhy- drous salt. Hmlrofluate of Ammonia. H 3 N.HI. 36.83. See Turner, 5th edit, p. 469. Hydrosulphate of Ammonia (H 3 N-|-HS. 34.25) is formed by heating a mixture of 1 part of sulphur, 2 of sal- ammoniac, anji 2 of unslacked lime. It is used as a re- agent, and for this purpose it is formed by saturating a solution of ammonia with hydrosulphuric acid. Hydrocyanate of Ammonia. H 3 N -|- HC 2 N. 44.54. Hydrosulpkocyanatc of Ammonia. H 3 N-f-HCyS 9 . 76.74. Trifluoboratc of A mmonia. 3H 3 N + BF 3 . 1 18.39. Dljluobor ate of Ammonia. 2H 3 N-f-BF 3 . 101.24. Fluoborate of A mmonia. H 3 N -f BF 3 . 84.09. Fluosilicate of Ammonia. H 3 N + SiF. '43.33. Carbosulphate of Ammonia. H 3 N + CS^. 55.47.* Salts of Phosplmreted Hydrogen. Phosphureted Hydrogen resembles ammonia in composi- tion, and in some of its properties; it is a feeble alkaline base, and combines with some of the hydracids. The salt * See Turner, 5th edit. p. 4C9. 316 Salts. Sulphur-Salts. best known is the hydriodate of phosphureted hydrogen, which is composed of 127.3 parts or 1 eq. acid, and 34.4 parts or 1 eq. base, and crystallizes in cubes. SECTION 4. ORDER III. SULPHUR-SALTS. The sulphur-salts are double sulphurets, just as the oxy- salts are double oxides. The sulphur-salts, with two metals, are so constituted, that if the sulphur in each were replaced by an equivalent quan- tity of oxygen, it would form an oxy-salt. The close analogy between the two orders of salts appears also from the fact, that hydrosulphuric and hydrosulphocy- anic acids unite both with ammonia and sulphur bases. The principal sulphur bases are the protosulphurets of potassium, sodium, lithium, barium, strontium, calcium, magnesium, and the hydrosulphate of ammonia ; and the sulphur acids are the sulphurets of arsenic, antimony, tung- sten, molybdenum, tellurium, tin, and gold, together with hydrosulphuric acid, bisulphuret of carbon, and sulphuret of selenium. The sulphur-salts are divided into families which contain the same sulphur acid ; the generic name of each family is formed from the sulphur acid terminated with sulphur (t ; thus the 'salts which contain persulphuret of arsenic or hydrosulphuric acid, as the sulphur acid, are termed arsenio- sulphurcts and hydrosulphurcts, and a salt composed of those sulphur acids, with sulphuret of potassium, is termed arsrnio- sulphurct, and hydro sulphuret of sulphuret of potassium, or simply hydrosulphurct of potassium * * Ifr. Hare has adopted a method of naming the sulphur-salts, founded on the nomenclature of the ozy-salts. He calls the electro- negative sulphuret an acid, and forms its name by changing the termi- nation of the element with which the sulphur is combined into ic, and Sulphur ets. 317 1. HYDRO-SULPHURETS. The salts of this family have hydrosulphuric acid for their electro-negative ingredient; most of them are soluble in water, are decomposed by exposure to the air and by acids. Hydro-sulphurct of Potassium. KS -|- HS. 72.35. The anhydrous salt may be obtained by heating to low redness anhydrous carbonate of pot issa in a tubulated retort, through which a current of hydrosulphuric acid is transmit- ted. It forms, when cold, a white, crystalline solid. The hydrous salt has an acrid, alkaline, and bitter taste. Jfydro-wlphuret of Sodium. NaS + HS. 56.5. Hydro-sulphur tt of Lithium. LS -j- HS. 43.2. Hydrti'sulphuret of Barium (BaS -f- HS. 101.9) is formed by the action of hydrosulphuric acid on a solution of baryta, excluded from the air. It crystallizes in four-sided prisms, and is very soluble. Hydro-sulphuret of Strontium. SrS -f- IIS. Eq. 77. Hydro-sulphurct of Calcium. CaS + HS. Eq. 53.7. Hydro-sulphurct of Magnesium. MgS -\- HS. Eq. 45.9. 2. HYDRO-SULPHOCYANURETS. The acid of these salts is the hydrosulphocyanuric acid. Hydro-sulphon/anurct of Potassium (KS-fHCyS 2 . 1 14.84) is a white, crystalline solid, soluble in water and in alcohol. Hydro-sulphocyanurrt of Hydrosulphate of Ammonia (H3N + HS) + (HCyS 2 . 93.84)' exists in long, brilliant crys- tals, of a lemon-yellow color. 3. CARBO-SULPHURETS. The acid of this family is the bisulphuret of carbon. Carbo-sulpJiurtt of Potassium (KS + CS 2 . 93.57) is pre- pared by agitating bisulphuret of carbon with a strong alco- holic solution of protosulphuret of potassium. The liquid, when set at rest, separates into three layers, the lowest of which is the carbo-sulphuret of potassium. On evaporation, prefixing sulph or sulpha. Thus, persulphuret of arsenic he calls sulpft- arsenic acid, and its sulphur salts, sulpharseniates. Hydrosulphuric acid he denominates sulphydric acid, and its salts sulphydrat es ; so of the rest. 27* 318 Salts. Molybdo-sulphurets. a deliquescent, yellow, crystalline salt is deposited, sparingly soluble in alcohol. The Carbo-sulphuret of Sodium (NaS + CS 2 . 77.72) and the Carbo-sulphuret of Lithium (LS -\- CS 2 . G4.42) are simi- lar to the preceding. Carbo-sulphuret oftfa Hydrosulphate of Ammonia (H 3 N. HS + CS 2 . 72.57) is a very volatile salt, and must be kept in bottles tightly corked. Exposed to the air, it absorbs water and becomes red.* 4. ARSENIO-SULPHURRTS. Each of the three sulphurets of arsenic is capable of acting as a sulphur acid ; giving rise to- three distinct families of sulphur salts, arsenio-protosulphurets, arsenio-sesquisulphttn f.< t and arscnio-persulphurets. The persulphuret of arsenir i.< the most powerful of these acids. The arsenio-persulphurets of the alkalies and alkaline earths, are very soluble in v have a lemon-yellow color when anhydrous, but colorless when combined with water of crystallization, or in solution ; but those of the second class of metals are generally in- soluble. 5. MOLYBDO-SULPHURETS. The acid in this family is the tersulphuret of molybdenum. The most remarkable of these salts is Molybdo-sulphurct of Potassium, (KS + MoS 3 . 151.23,) which is formed by decomposing a solution of molybdate of potassa with hydrosulphuric acid ; on evaporation, beautiful crystals with four and eight sides are deposited. Berzelius de- scribes this compound as the most beautiful which chemistry can produce. The crystals, by transmitted light, are ruby- red, and their surfaces, while moist, and also the solution which yields them, shine like the wings of certain insects, with a metallic lustre, of a rich green tint. * The carbo-sulphuret of barium, (B&S -f- CS*. 123.12,) the carbo-sul- phuret of strontium, (SrS-J-CS'. 98.22,) and the carbo-sulphuret of ail c hi m , (CaS -f- CS*. 74.92,) may be obtained by acting on bisulphurct of car- bon with a solution of the protosulphurete of these metals. The solu- tions are orange or brown, and* the crystals, when dry, are of a citron- yellow color. Carbo-sulphuret of magnesium. MgS-^j-CS 8 . 67.12. Haloid Salts. 319 6. ANTIMONIO-SULPHURETS. The acid of this family is the sesquisulphuret of antimony, and the only salt examined is the antimonio-sulphurct ofpo- tassium, which may be formed by mixing 2 parts of car- bonate ofpotassa, 4 of sesquisulphuret of antimony, and 1 of sulphur, and fusing the mixture. 7. TuNGSTO-SULPHURETS. The best known of this family is potassium. When a solution of tungstate of potassa is decomposed by hydrosul- phuric acid, and the solution evaporates, anhydrous, quadri- lateral, flat prisms are deposited, of a pale-red color, which is the tungstosulphuret of potassium. This salt unites with tungstate of potassa as a double salt. SECTION 5. ORDER IV. HALOID SALTS. This order includes substances composed, like the pre- ceding salts, of bi-elementary compounds, one or both of which are analogous to sea-salt in composition. The haloid acids belong generally to the electro-negative, and the haloid bases to the electro-positive metals. The following are the principal groups or families : ^ 1. Hydrar go-chlorides. The haloid acid is the bichloride of mercury ; they are obtained by mixing their ingredients in the ratio of combination, and setting aside the solution to crystallize. 2. Auro-chlorides. The acid in this family is the ter- chloride of gold ; they are prepared like the preceding; most of them have an orange, or a yellow, color. 3. P latino-chlorides. The haloid acids in this family are the protochloride and bichloride, of platinum. 4. Palladio-chlorides are salts in which the chlorides of palladium act as haloid acids, combining with many of the metallic chlorides. 320 Salts. Haloid Salts. 5. Rhodio-chlorides are formed by the action of sesqui- chloride of rhodium on the chlorides of potassium and so- dium. 6. The Chlorides of Iridium and Osmium are the haloid acids of the iridio-chhrides and the osmio-chlorid;>. 7. Oxy-chlorides. This family embraces a large number of compounds, in which a metallic oxide is united with a chloride, generally of the same metal, but often of other metals. These salts are commonly termed submuriates, on the supposition that they consist of hydrochloric acid, com- bined with two or more equivalents of an oxide. Ory-chloridrs of Iron. When the crystallized protochloride of iron is strongly heated in close vessels, a deep green osy-chloride, in scaly crystals, is formed. A Ox ij-clil aride of Copper constitutes the paint called Brunswick preen, and is prepared by exposing metallic copper to hydrochloric acid. This is the compound formed by the action of sea-water on the copper of Vrss.'Is. Oxy-chtoride of Lead may be formed by adding pure ammonia to a hot solution of chloride of lead ; another ozy-chloride Hie pigment called patent yellow is prepared by the action of moist sea-salt on litharge. 8. Chlorides with Ammonia. The perchlorides of tin and some other metals absorb ammonia at common temperatures, and most of the other chlorides absorb it when gently heated ; but most of these compounds lose their ammonia, on exposure to the air, and nearly all, by heat. 9. Chlorides with Pliosphureted Hydrogen. These are very'similar to those with ammonia, and are not of sufficient importance to be inserted in this place. 10. Double Iodides. These compounds have not yet been closely studied, but the iodides probably form with each other an extensive family of salts. The most important are the Platino-biniodide of Potassium, prepared by digesting an excess of biniodide of platinum in a concentrated solution of iodide of potassium, and the Pl&tino-biniodide of Hydrogen, which is prepared by acting on biniodide of platinum with a cold dilute solution of hydriodic acid. 11. Oxy-iodides. The best known of this family are those formed by the oxide and iodide of lead. The double bromides have not yet been studied. , Organic Chemistry. 321 12. Double Fluorides. There are several extensive fami- lies of these salts, in which the fluorides of boron, silicon, titanium, and other electro-negative metals, are the acids, and the fluorides of the electro-positive metals are the bases. 13. Double Cyanurets and Fcrro-cyanurets. The double cyanurets constitute a large and important family of salts, of which the principal are the ferro-cyanurets, ferro-sesqui- cyanurets, zinco-cyanurets, cobalto-cyanurets, nicco-cyanu- rets, and cupro-cyanurets, in which the proto-cyanuret of iron, sesqui-cyanuret of iron, cyanuret of zinc, cobalt, nickel, and copper, are the electro-negative cyanurets. (See Turner's Elements, p. 487.) CHAPTER IV. NATURAL SUBSTANCES. ORGANIC CHEMISTRY. Organic chemistry treats of those substances which are of animal or vegetable origin, and which are therefore called organic. These substances differ from inorganic substances, in being composed of the same elements, oxygen, carbon, and hydrogen, often with the addition of nitrogen, which is most abundant in fungous plants and animal substances. On the other hand, inorganic compounds are composed of very dif- ferent elements; a few other constituents, as, iron, silica, potassa, sulphur, phosphorus, etc., are sometimes detected in small quantity in organic substances, but can rarely be re- garded as essential constituents. These compounds differ chiefly in the proportions of their constituents ; hence many of them are easily convertible into each other. A second characteristic of organic substances is the facility with which they may be decomposed, and especially in being, Vegetable Chemistry. without exception, decomposed by a red^ieat, and often by a lower temperature ; if heated in the open air, they are con- verted chiefly into water and carbonic acid. With a few exceptions, organic substances cannot be formed artificially, by the direct union of their elements ; they are obtained only as already existing in organic bodies,* or by the conversion of one into another, as of sugar into al- cohol. Many organic acids and alkalies combine with inorganic alkalies or acids, and form compounds, which, although not entirely of animal or vegetable origin, are usually described in connection with their organic constituents. VEGETABLE CHEMISTRY. Most vegetable substances consist of hydrogen and carbon, usually with oxygen ; in fungous plants, and in some others, nitrogen is also present. Proximate Principles. All compounds, which exist in plants ready formed without artificial processes, as, gum, sugar, starch, etc., are called proximate principles ; the pro- cesses by which they are separated, constitute proximate. analysis. Ultimate Analysis consists in the reduction of organic compounds into their elements. This was formerly done by destructive distillation ; the substance was put into a close vessel and decomposed by a high temperature ; the products were collected and examined. The process is now gener- ally conducted by means of the oxide of copper, which easily parts with its oxygen to the carbon and hydrogen of the substance, forming carbonic acid with the former, and water with the latter. These new compounds are collected, and from their weight may be known the weight of the carbon * The agent by which organic bodies are formed is life, whose na- ture and mode of action we do not understand. Vegetable Adds. 323 and of the hydrogen. The loss of oxygen in the oxide of copper is also noted, and compared with the quantity in the carbonic acid and water. The excess of the latter over the former, is the amount derived from the substance under ex- amination; and, if there be no such excess, it is inferred that there was none in the substance. Before entering upon a description of the various vegetable principles, it will be proper to notice the results of the late investigations of Wohler, Liebig, Pelouse, and Dumas. 1. Amides, or Amidcts. Theory. Dumas discovered that when crystallized oxalate of ammonia, represented by the formula C'W + NH 3 was distilled, a white, tasteless powder was obtained, which he called oxamide. On analyz- ing this, he found it composed of C^ 2 -f- NH 2 ; or it is oxalate of ammonia deprived of one equivalent or atom of water. On heating this with potassa, ammonia is disengaged, and oxalate of potassa formed, by which treatment the atom of water is restored. The term amide has been generalized and applied to all those anhydrous compounds of an acid and ammonia, which by heat may be deprived of an atom of water ; or to all those compounds which, by adding an atom of water, can be con- verted into a salt of ammonia ; hence we have from bcnzoate of ammonia (C 14 H 5 O 3 -j-H 3 N) a substance called benzamide, (C^H^O 2 -f H 2 N,) differing from the former by HO, or 1 equivalent of water less. Hence it is inferred that there must be such a compound as H 2 N, to which Liebig has given the name amide, as potassamide, composed of K -j- H 2 N. Dumas has given to these compounds the name of amidet. Thus oxamide he calls amidet of oxide of carbon, (H 2 N -fC 2 O 2 .) 2. Benzoyl. Theory. By the recent investigations of Wohler and Liebig, on the volatile oil of bitter almonds, they have inferred that benzoic acid has a base, to which they give the name of benzoyl, composed of C 14 H 5 O 2 . They also ob- 324 Vegetable Chemistry. tained chloride, bromide, sulphuret, and cyanide of benzoyl, from which it is inferred that benzoyl exists as a separate compound, and that it is capable of combining with other simple bodies. 3. Ethers. Theory. Dumas considers the base of ether to be C 4 H 4 . Liebig regards the base as thus constituted, C 4 II 5 . Sulphuric ether, according to the latter, is an oxide of C 4 H 5 , and is represented by C 4 H5O. Alcohol is a hy- drate of sulphuric ettier, or C^H)-)- HO. The radical of ether (C 4 H 5 ) is capable of combining with chlorine, bromine, iodine, and forms chloric, bromic, and iodic ethers. 4. Pyr acids. Theory. When several of the vegetable acids are distilled, they undergo decomposition, and new acids are generated, which are called by the term pyracids. Tar- taric acid becomes pyrotartaric acid ; gallic, pyrogallic ; and so of several others. The difference in composition seem- i< be that a quantity of water is expelled by the heat. 5. Theory of Substitutions. When oxygen, chlorine, bromine, and iodine, unite with various compounds, the latter give out hydrogen, and the process is termed dehydrogenizing. Thus, when dry chlorine gas is passed into pure oil of bitter almonds, (C^HH^-f-H,) it loses its atom of hydrogen, and an atom of chlorine is substituted, and the compound con- sists of C^HH^-l-Cl, a chloride of benzoyl. This and other analogous facts have been generalized by Dumas, and the following general conclusions made : 1. That when a body is subjected to the dehydrogenizing action of O, Cl, Br, and I, it gains one of the latter for each atom it loses of hydrogen. 2. But if the body contain water, it loses its hydrogen without any substitution. If, after this, hydrogen is extracted, the substitution proceeds as before. 3. The fundamental radical and its derivatives will be neutral or alkaline, whatever be the portion of oxygen, hy- drogen, &c., entering into it. But when the oxygen, bro- Vegetable Acids. 325 mine, &,c., enter into combination with this radical, they render it acid. T. SECT. 1. VEGETABLE ACIDS. Vegetable acids are, for the most part, less liable to spon- taneous decomposition than other organic substances, al- though none of them can exist at the temperature of a red heat ; they all contain carbon and oxygen, and most of them hydrogen also; generally, they have more oxygen than would be sufficient to form water by combination with the hydro- gen ; but a few have these elements in the same ratio as in water, while in benzoic acid the hydrogen is in excess. Ojr.nlir. Add (C 2 Q3. 36, T. 2CO + O. 36.24, L.) was dis- covered by Scheele, in 1776, and is found in several plants, among which is common sorrel, the sour taste of which is caused by the presence of oxalic acid ; it is obtained also by the action of nitric acid on sugar. Many other organic sub- stances, as starch, gum, most of the other vegetable acids also, wool, silk, etc., are converted into oxalic acid by the action of nitric acid ; it contains more oxygen than any other organic substance. Properties. Oxalic acid is sold in small, slender crystals, and much resembles Epsom salts, for which it is sometimes mistaken with fatal consequences. But, although a powerful poison, it may be tasted without danger, when its strong acidity will easily distinguish it; if taken by accident, pow- dered chalk in water or magnesia should be administered. Oxalatcs of Potassa. There are three of these compounds, one of which, the binoxalate, (HO.CW, KO.C 2 O? + 2Aq. 155.63,) is often sold under the name of essential salt of lemons, for removing the stains of iron-rust from linen; a so- lution of oxalic acid will answer the same purpose. Quad- roxalate of potassa is sold for the preceding, and is formed by dissolving the binoxalate in hydrochloric acid,-and crystal- lizing. In this way the salt is manufactured on a large scale. 28 326 Vegetable Chemistry, Oxalaie of Lime (CaO.C Q O 3 + 2Aq. = 82.74) exists in several species of lichen, and, when recently precipitated, is a snow-white flocculent powder. This salt may be distin- guished from most other precipitates by its being insoluble in water, ammonia, and acetic acid, but soluble in nitric and hydrochloric acids. On this account, lime may be detected in solutions from which all other metallic oxides have been separated : thus these oxulates are used to separate lime from magnesia. Lime may also be used to detect oxalic acid. Acetic Acid. C 4 H 3 Q3. 51.48. This acid exists in the of many plants, and is generated in large quantities, in the destructive distillation of vegetable substances, and in the acetous fermentation : it is the acid of common vinegar. Distilled vinegar is transparent and colorless, of a strong acid taste and an agreeable odor. To obtain acetic arid \\\ a purer state, saturate distilled Vinegar with a metallic oxide, as of copper or lead, and distil the compound. Pyroligne- ous acid consists of acetic acid mixed with tar and a volatile oil, and is made by the distillation of wood. The concen- trated acid is very strong and volatile, with a refreshing odor ; its vapor is inflammable. Numerous salts are formed by this acid. Acetate of Lead. 1 eq. acid, 1 protoxide of lead, 3 water. This substance, commonly known under the name of sugar of lead, is prepared by dissolving either the carbonate of lead (white lead) or litharge in distilled vinegar. Like most of the compounds of lead, it is highly poisonous. It is one of the most important of the acetates. It is used in pharmacy, and by dyers and calico-printers for the preparation of acetate of alumina and iron. Acetates of Copper. Of these there are three or four. Verdigris is a variable mixture of them, and is prepared in France by covering copper with the refuse of grapes, after the juice has been extracted. In England, a better article is prepared by covering copper plates with cloth soaked in pyrol igneous acid. Vegetable Acids. 327 Acetate of Alumina is extensively employed by calico- printers as a mordant for fixing colors. Acetate of Iron is also used for the same purpose. Acetate of Ammonia has long been used in medicine. Acetate of Zinc is sometimes applied externally as a remedy, and Acetates of Tin have been recommended as mordants for the use of dyers. Ace- tate of Mercury was once used in medicine. Malic Acid. C 4 H 2 O 4 . 60. This acid is contained in grapes, currants, gooseberries, oranges, apples, and in most of the acidulous fruits. It is also obtained by the action of nitric acid on J of its weight of sugar ; it forms salts with metallic oxides, called malatcs. Citric Acid. C 4 H 2 O 4 . 60. This acid is also found in many acidulous fruits, especially in limes and lemons, from which it is usually obtained. It has an agreeable flavor, and is an excellent substitute for lemons ; it is used in the prep- aration of lemon sirup, in which, however, tartaric acid is largely employed, being much less expensive, but of very inferior flavor. Citric and malic acids are isomeric. Tartaric Acid. C 4 H2O 5 . 66.24. This acid also exists in acidulous fruits, usually in combination with lime or potassa. Tartaric acid is used with the bicarbonate of soda for an effervescing drink ; it forms numerous salts, many of which are double. Bitartratc of Potassa. In an impure form, this is known by the name of crude tartar, and is found incrusted on the sides of wine casks, colored by the wine; when purified, it is white, and is known by the name of cream of tartar. It is used for the preparation of tartaric acid, and as a medicine. Tartrate of Antimony and Potassa. This compound is sold under the name of tartar emetic, and is prepared by boil- ing sesquioxide of antimony with cream of tartar. It is neu- tralized by vegetable astringents, as tea, or Peruvian bark, which may therefore be used as an antidote, in case of taking a too powerful dose. It is a white solid, slightly efflores- cent, and is composed, according to Phillips, of I atom of 328 Vegetable Chemistry. bitartrate of potassa, 3 sesquioxide of antimony, and 3 of water. Tartrate of Potassa and Soda is prepared by saturating an excess of acid in tartar, with carbonate of soda. It has long been used in" pharmacy under the name of Roche lie Salt and Sel de Seignctte. It consists of 1 atom of tartrate of potassa, 1 atom of tartrate of soda, and 10 atoms of water.. Tannic Acid, or Tannin. C^HK) 1 *. 212. This substance exists in gall-nuts, (the excrescences of several species of the oak,) in the bark of most trees, in tea, and in most vegetable astringents, and is the cause of their astringency. \Yith gelatin or glue, it forms an insoluble compound, which is the basis of leather. Hence leather is prepared by soaking skins in water, which contains ground bark, the tannic acid of which is taken in solution by the water. Ezp. To a strong solution of gelatin (common glue answers well enough) add a strong infusion of gall-nuts; a white precipitate will be formed, and may be collected upon a glass rod and pressed together, forming a strong extensible mass, resembling new leather. When ex- posed to the oxygen of the air, it is gradually converted into gallic acid. Gallic Arid. C 7 !!^ 5 . 85. This acid also exists in gall- nuts and in the bark of trees, but is more abundantly ob- tained by the oxidation of the tannic acid of gall-nuts. Common ink owes its color to the compounds of tannic -MM! gallic acids with the sequioxide of iron, and may be extem- poraneously prepared by adding to an infusion of gall-nuts a solution of copperas, which has been exposed to the air.* Some of the most important of the remaining vegetable acids are the following : Mcllitic Acid (C. 91.8 + 10 + 80 = 181.8) exists in cinchona bark, in combination with lime, quinia, and cinchonia. Vyrocitric Acid. C 10 H 2 O 3 . 61.2 + 2 + 24 = 87.2. Racemic Acid (C 4 H 2 O 5 . 24.48 + 2 + 40 = 66.48) is as- sociated with tartaric acid in the juice of the grape. Benzine Acid (C 14 H5Q 3 . 85.68 + 5 + 24=114.68) ex- ists in gum benzoin, from which it is commonly extracted, in the balsams of Peru, and in several other vegetable sub- stances, in the urine of the cow and other herbaceous ani- mals. This acid crystallizes in soft, white scales, flexible, transparent, and of a pearly lustre ; or in hexagonal needles ; is slightly biting, but of a sweetish taste, producing sensation in the throat ; fuses at 250, and sublimes at 300. Exp. Suspend a small branch of a shrub in a tall glass, without a bottom ; place a small quantity of the acid upon a plate of metal ; place the jar over the plate, at the same time applying the heat of a lamp to evaporate the acid ; the branch will be covered with delicate white crystals. Meconic Acid (C 7 H 3 O 7 . 42.84 + 2 + 56=100.84) is found in the poppy, in combination with morphia, and crys- tallizes in white, transparent scales. Pyromeconic Acid. C 10 H; 3 O 4 . Metameconic Acid (C 12 H 4 O 10 . 73.44 + 4 + 80 = 157.44) is obtained from the meconic by boiling its aqueous solution. 28* 330 Vegetable Chemistry. Pyrogallic Acid (CSHW 36.72 + 3 + 24 = 63.72) is obtained by heating galJic acid to 419. Metagallic Add (C^HW 73.44 + 3 + 24 100.44) is formed by beating gallic acid to 480. Ellagic Acid (C7R2CH. 42.84+2 + 32=76.84) is very similar to the preceding. SuccinicAcid (C 4 H2O3. 24.48 +2 + 24 =50.48) exists in amber, and is obtained by the aid of heat. It is obtained in three states : 1. Combined with an atom of water, which, when pure, is the crystallized acid of the shops. 2. With J an atom of water, produced by keeping the crystallized acid for a long time between the temperatures of 260 and 284. 3. Anhydrous. The compounds which this acid forms \\itli bases are termed succinates. Mncic Acid. C6H5Q8. 36.72 + 5 + 64 = 105.72. Camphoric Acid (&*>HO*. 122.4 + 10+ 40 178.4) is obtained from camphor by nitric acid. Vakrianic Acid (C 10 H^O3. 61.2 + 9 + 24 = 94.2) ex- ists in the root valerian, and is obtained by distillation. Rocellic Acid. C^H^O 4 . 97.92 + 16 + 32 = 1 45.1>2. Moroxylic Acid is found, in combination with lime, on the bark of the white mulberry. Oily Acids, so called because they are obtained from oils or fat, and enter into the composition of soaps. Stearic Acid (CH 6 O 5 . 527) is obtained from soap, and is a white, tasteless, inodorous substance, insoluble in water, and burning like wax. Its salts are termed stearates. Margaric Acid (C 70 H 70 O9. 562) is distinguished from the preceding by fusing at 140. When distilled with lime, a white substance is obtained, called margarone. Okie Acid (C 70 H 62 O 7 . 538) is obtained from the soap made from linseed oil and potassa. It burns like the fixed oils, and forms salts, or soaps, called olcates. When olive oil is mixed with half its weight of concentrated sulphuric acid, three acids are formed, one of which has been called sulpho- okic ; and this, when decomposed, affords hydro-olcic acid. Vegetable Acids. 331 From this last compound two liquids have been obtained, of the same composition with olefiant gas. The one has been called olein, the other elain. Olcin (C 6 H 6 ) is a white liquid, lighter than water, strong odor, very combustible, burning with a greenish flame, and yielding a poisonous vapor. Elain is composed of C 9 -|- H 9 , and burns with a fine white flame. The Azulmic Add, (C 8 H 4 N 4 O 4 ,) the Indigotic, (C^HTJ N1O 15 ,) which is obtained by boiling indigo in rather dilute nitric acid, and the Carbazotic acids, (C 15 N 3 O 15 . 252,) also, are obtained from indigo containing nitrogen. Pcctic Acid (C n H 7 O 10 . 153) has been imperfectly ex- amined. Crenic Acid (108) was discovered by Berzelius, in 1832, in the water of Porla well, in Sweden. It is inodorous, a sharp, followed by an astringent taste, yellow and trans- parent; very soluble in water arid in alcohol. When the solution is exposed to the air, apocrenic acid is formed. Its salts are termed crenates, and resemble extracts in ap- pearance, but are incapable of crystallizing. Apocrenic Acid (132) was obtained by digesting the ochre of Porla well with potassa, and precipitating the acid by means of acetate of copper. The apocrenate of copper falls, from which the acid is separated by the action of hydrosui- phunc acid, absolute alcohol, and potassa. It is a brown substance, resembling a vegetable extract. Crenic and apo- crenic acids have been detected in many waters, and in the vegetable mould of soils. There are also a numerous class of compound acids. For a complete description of the vegetable acids, the student is referred to Thompson's Chem., Organ. Bodies. Cyanogen and its Compounds. A numerous class of bodies are formed by the combination of cyanogen with other substances which exist in the vegetable and mineral king- doms ; for a description of which, see Webster's Chem., and also Thompson's Chem., Organ. Bodies. 332 Vegetable Chemistry. SECT. 2. VEGETABLE ALKALIES. The existence of vegetable alkalies was not known until the present century, and very little attention was given to them until 1816. They are eighteen or twenty in number. Their constitution is remarkable, as they each contain 1 equiv. of nitrogen in eaqh equiv. of the alkali. The equiva- lents of oxygen vary from one to six, of hydrogen from twelve to twenty-two, and of carbon from twenty to thirty- four ; all, which have been analyzed, consists of these four elements. In vegetable bodies they usually exist in combi- nation with acids, forming salts. The method of preparation is nearly the same for all of these alkalies; the substance which contains one of them is steeped in a large quantity of water, which dissolves the salt that contains it; the solution is boiled for a short time with lime or magnesia, and the vegetable alkali is set free in ;m insoluble state, and may be collected on a filter with the Inm ; if then boiled in alcohol with powdered charcoal, it is dis- solved by the former, and purified by the latter ; then, by filtering while hot, it is separated from the charcoal, and the lime with which it was mixed; it is deposited from the alco- hol on cooling, by evaporation. Morphia. C 34 H 18 N 1 O 6 = 284. This alkali is the narcotic principle of opium, in which it is combined with sulphuric and meconic acids, and is associated with several other vege- table alkalies, and with gummy, resinous, and coloring mat- ters. Opium contains about nine and a half per cent, of mor- phia ; when pure, it is very insoluble in water, and conse- quently but little poisonous ; but when in the state of a salt, as in opium, it is a very powerful poison ; one half a grain in solution will produce alarming effects on the animal system. When opium has been administered as a poison, the presence of its morphia may be detected by a process too elaborate to be inserted here. A skilful chemist will detect a single grain of morphia in 700 grains of water. Some of the salts of mor- Vegetable Alkalies. 333 phia are useful as medicines; of which ihe-Jiydrochlorate and acetate are the principal. Narcotina(C 40 R^NO^ = 370.24) was discovered by Des- rone, in 1803, and is obtained from opium ; it is a white sub- stance, and may be taken into the human stomach without sensible effects, but it is speedily fatal to dogs. Cinchonia (C 20 H 12 NO1J= 153) and Quinia, (C2<>Hi 2 NO2 162.) These two alkalies were detected by Pelletier and Caventou, in 1820, in Peruvian bark, and impart to it its value as a medicine. Cinchonia is found in the pale bark ; quinia, with a little cinchonia, in the yellow bark ; and both in the red bark. Cinchonia is insoluble in cold water, and nearly so in hot water ; in boiling alcohol it is freely dissolved, and the solution has an intensely bitter taste ; some of its salts are soluble in water. Quinia, or Quinine, is also almost insoluble in water, but with alcohol forms an intensely bitter solution. Quinia forms several salts, one of which, the sulphate, is manufactured in large quantity for medical purposes, and is commonly sold by the name of quinine. It is soluble in al- cohol, or slightly in pure water, and freely if the water is slightly acidulated by sulphuric acid; the solution, although containing but a minute portion of quinia, is intensely bitter. On account of its high value, sulphate of quinia is often adulterated with gum, starch, sugar, magnesia, and various other substances ; gum and starch are insoluble in alcohol, and may be detected by dissolving the suspected quinia in boiling alcohol. Sugar may be detected by adding pearlash to the solution in water, when the quinia will be thrown down, and the sweet" taste may be perceived; magnesia will be left after burning a portion of the adulterated article. Strychnia (C^H^NO 3 237.75) was discovered in 1818, by Pelletier and Caventou. This remarkable alkali is found in the nux vomica and in the upas-tree. It is freely soluble in alcohol, nnd but slightly so in water ; although nearly insoluble in the latter, the minute portion which is taken up, commu- nicates to the water the most intense bitterness; a single 334 Vegetable Chemistry. grain of strychnia will render eight gallons of water bitter. It is one of the most virulent poisons yet discovered ; half a grain in the throat of a rabbit occasioned death in five minutes. Its action is always accompanied by symptoms of locked-jaw. Emetia. This alkali constitutes 16 per cent, of ipeciim- anha, and appears to be the sole cause of its emetic proper- ties. Sanguinaria is a peculiar alkali, discovered, by Mr. Dana, in the blood root, (sanguinaria Canadensis.) Its salts have a red color. Nicotina is the peculiar principle of tobacco ; it is a viru- lent poison. Codeia; discovered in 1832, by Robiquet, in the hydrochlo- rate of morphia. When taken into the stomach in doses of from 4 to 6 grains, it produces an excitement similar to in- toxication, followed by depression, nausea, and vomiting. jBrt/cia, or Brucina, resembles strychnia, and may be pro- cured from the nuz vomica. It is intensely bitter, less poison- ous than strychnia, but similar in its effects. Conia is the active principle of conium-maculatum , or hem- lock, and is the most virulent poison known, with the excep- tion of hydrocyanic acid. Parillia, or Parillina, exists in the common sarsaparilla of commerce. Its color is white, taste, sharp and bitter, and, when swallowed to the extent of 13 grains, produces nausea, vomiting, diminishes the rapidity of the circulation, and acts as a sudorific. SECT. 3. NEUTRAL SUBSTANCES. Sugar. C 12 H 10 O 10 = 162.24. Sugar is found in most ripe fruits, but more abundantly in the sap of the maple-tree, in the sugar-beet, and in the sugar-cane ; from the latter it is obtained by evaporating the juice by a moderate ebullition, until the sirup is sufficiently thick to crystallize on cooling. During this operation, lime water is added to neutralize the Neutral Substances. 335 acid present, and to remove impurities which rise with the lime in a scum to the surface; it is next drawn off into shal- low coolers, in which it becomes a soft solid. Lastly, it is put into barrels with holes in the bottom, through which the molasses gradually runs out, leaving raw or brown sugar. Raw sugar is purified by boiling it with the white of eggs or bullock's blood and lime water ; it is then received into con- ical vessels, and in cooling assumes the form of loaf sugar. When two pieces of loaf sugar are rubbed together in the dark, phosphorescence is observed ; it is obtained in large crystals by fixing threads in a sirup, which evaporates grad- ually in a warm room ; in this state it is called rock-candy. Sugar does not deliquesce when exposed to the air, except when impure, as raw sugar. It is soluble in an equal weight of cold water, and is much more soluble in warm water ; it is soluble in four times its weight of boiling alcohol, from which solution fine crystals are obtained. The vegetable acids diminish the tendency of sugar to crystallize, as in molasses. By the action of sulphuric acid, starch, and common wood, may be converted into sugar. Sugar of Grapes (C 12 H 12 O 12 ) contains rather less carbon than common sugar,, and is rather less sweet. Honnj consists of two kinds of sugar, one of which, when separated, crystallizes, and the other is uncrystallizable. Be- sides sugar, it contains gum, and probably an acid ; when di- luted with water, honey undergoes the vinous fermentation. Common sugar requires the addition of yeast for this change. Manna is the concrete juice of several species of ash, and owes its sweetness, not to sugar, but to a distinct principle called mannite. Liquorice owes its sweetness to a saccharine principle which is quite distinct from sugar. Starch. Starch exists abundantly in the vegetable king- dom. It is the principal constituent of most kinds of grain, potatoes, and other farinaceous substances. It is obtained 336 Vegetable Chemistry. from potatoes by washing them in cold water, when the glu- ten, which is the other principal constituent, remains in the hand, and the starch is mechanically diffused through the water. The water is then allowed to stand, and the starch subsides, while the saccharine and mucilaginous matters remain in solution. When made from the dough of wheat flour, the water containing the soluble and insoluble parts of the flour is allowed to ferment ; acetic acid is thus formed, which dissolves the gluten, and facilitates the separation of the starch. Starch is easily converted into sugar. In the germination of seeds, and in the malting of barley or other grain, this change takes place. If starch is boiled for a considerable time in water, which contains -fa its weight of sulphuric acid, it is converted into a kind of sugar like that obtained from grapes. Arrow-root, prepared from the root of a plant, is a very pure starch. Sago, prepared from the pith of an East India palm-tree, and tapioca and cassava from the root of a plant, are essentially the same. Gluten. Gluten exists with starch in most kinds of grain, which are chiefly composed of two principles. It is obtained from wheat flour by washing out the starch and soluble mat- ter, and boiling the remainder in alcohol. On adding water and distilling off the spirit, it is deposited. It is without taste, very tenacious, elastic, and insoluble in water. When kept warm and moist, it ferments. The tenacity of common paste is owing to the gluten which it contains. The rising of bread is caused by the fermentation of gluten, the tenacity of which retains the bubbles of carbonic acid gas formed in fermentation. Gluten has been resolved into four distinct principles, viz., vegetable albumen, emulsin, mucin, and glutin. These substances are obtained by the action of alcohol upon the gluten of wheat. Gum. Under this name are included all those vegetable principles which form, when dissolved in water, an adhesive, Oils. 337 viscid liquid, called mucilage, and which yield an acid, called mucic acid, when boiled with four times their weight of nitric acid. Gum is insoluble in ether and alcohol, and is precipitated by them from its aqueous solution, as an opaque, white substance; but, with acids and alkalies, it is more soluble than in pure water. Gum Arabic is the most common variety of gum ; it is obtained from several species of acacia or mimosa in Africa and Arabia. Gum Senegal differs in no important respect from gum arabic. The gum of the peach, plum, and cherry-tree, although identical in composition with gum arabic, differs in being insoluble in cold water; after being boiled, however, it assumes the characters of that gum. Gum Tragacanth differs from gum arabic in containing a large portion of bassoric, starch, and water; it is tougher than common gum, which is quite brittle. Gum tragacanth is therefore a very useful ingredient in paste. The jelly of fruits is distinct from gum in some properties, but is nearly allied. Lignin. Lignin, or the woody fibre, constitutes the fibrous structure of plants, and is the most abundant prin- ciple in them. The common kinds of wood contain about 96 per cent, of lignin. It is insoluble in alcohol or water. With strong alkalies or acids, it is changed. With sulphuric acid, it is changed into gum, and, on boiling, is further changed into a sugar like sugar of grapes. Straw, bark, and linen, in the same way, may be converted into sugar. SECT. 4. OILS. These substances are divided into fixed and volatile oils. The former are not much affected by a heat which does not decompose them, while the latter rapidly pass away in vapor. The greasy stain of the former on paper, or any other sur- face, is permanent ; that of the latter soon disappears. 1. Fixed Oils. The vegetable fixed oils are usually ob- 29 338 Vegetable Chemistry. tained from seeds; as the almond, linseed, and poppy-seed. Olive oil, however, is extracted from the pulp around the stone. The density of these oils is less than water, varying from .9 to .96. They are solid at a low temperature. They burn with a clear, white light. By exposure to the air, they become rancid, and at length viscid. In this change, oxygen is absorbed ; and the oil itself probably undergoes some change, although it has been supposed that rancidity was caused by the acidification of some mucilage present. By heating the oil in open vessels, it acquires the property of drying rapidly ; in which process much oxygen is absorbed, and carbonic acid and hydrogen given off. Drying oils are used for paint, and, when mixed with lampblack, constitute printers' ink. Drying oils sometimes absorb oxygen so rapidly as to set fire to combustibles. Spontaneous com- bustion often occurs where cotton has been moistened with them. By means of mucilage or sugar, the fixed oils may be permanently suspended in water. Such a mixture is called an emulsion. With ammonia, they form a soapy liquid called volatile lini?nent, which is a direct compound of oil and the alkali. The fixed alkalies have a similar action in the cold, but, when heated, soap is generated. A further notice of soaps will be found under Animal Chemistry. The fixed oils consist of two proximate principles, one of which, called margarine, is solid at common temperatures, while the other is fluid, and is called oleine.* These oils consist of carbon, hydrogen, and oxygen. The principal fixed oils are the following : Olive Oil, which is expressed from the pericarpum of the fruit of the common olive, (olea Europea.) By the action of hyponitrous acid, the solid substance called elaidin is formed. It contains an acid called claidic, which combines with alkalies and forms soaps. It is used as an article of luxury. * From tiaiov, oil. Oils. 339 Croton Oil is obtained from the croton tiglium of the East Indies, and possesses powerful purgative properties. Palm Oil has the consistency of lard, and is used in the manufacture of yellow soap. Cocoa-nut Oil is a white, hard substance, used as a sub- stitute for tallow.* 2. Volatile or Essential Oils. The flavor of aromatic plants is owing to the presence of volatile oils, which are obtained by distillation. Water must be added to the plants to keep them from burning. Some, however, are obtained by expressing the rinds of certain fruits, such as the orange, lemon, bergamot. Although usually of an agreeable odor, those oils have an unpleasant, acrid taste ; but, when diluted, some of them have an agreeable taste. They are but slight- ly soluble in water, and are freely dissolved in alcohol. Such solutions are commonly sold under the name of essences. Like the fixed oils, they burn with a clear, white light. They have the property of dissolving sulphur, and the solution is called balsam of sulphur. A few of these oils as the oil of turpentine, of lemons, and of copaiva contain only carbon and hydrogen ; others contain oxygen also. A few contain one or more additional elements, as sulphur and nitrogen. The principal volatile oils are, oil of turpentine, lemons, anise, juniper, camomile, caraway, lavender, peppermint, rosemary, cam- phor, cinnamon, cloves, sassafras, mustard, and bitter almonds. Common Spirits of Turpentine consists of resin dissolved in the oil of turpentine which last may be obtained by distillation. Camphor is a volatile oil, solid at common temperatures. On account of its toughness, it is pulverized with difficulty, unless a few drops of alcohol be added. It is insoluble in water, but is freely soluble in alcohol. Artificial camphor * The various kinds of wax such as beeswax, myrtle wax, and cow-tree wax are regarded as similar in composition with the fixed oils, and are classed by some chemists with them. 340 Vegetable Chemistry. may be formed bypassing a current of hydrochloric acid gas through oil of turpentine or oil of lemons. Camphor is very offensive to insects, which are prevented from devouring cab- inets of natural history, collections of birds, insects, etc., by placing pieces of camphor in the cases. Resins. Resins are the concrete juices of plants, solid, brittle, and without taste; they are good non-conductors of electricity, and, by friction, become negatively electrified; they are easily melted, and burn with a yellow flame and dense smoke. They are soluble in alcohol, ether, and the essential oils, but are quite insoluble in water. The different kinds of resin are numerous. Common Resin is procured by heating turpentine; the volatile oil is expelled, and resin remains. Turpentine is the juice of several species of pine-trees. Other resins are copal, lac, mastic, and dragon's blood. Copal is the most important, and is used for varnish. In- dian ink is a solution of borax, lac, and lampblack. The uses of resin are various. Dissolved in oil or alco- hol, and diluted with spirits of turpentine, they form various kinds of varnish. Sealing-wax is made of lac, turpentine, and common resin. It is colored red with cinnabar or red lead, or black with lampblack. The soot, which is procured from the combustion of res- inous wood, turpentine, or resin, is lampblack. When tur- pentine is extracted by heat, it is partially changed, and be- comes tar. When tar is thickened by boiling, it becomes pitch. Amber is a fossil substance, consisting of a peculiar bitumi- nous matter and resin ; it often contains insects. Balsams are the juices of some kinds of trees. Some are solid, others are liquid: They are composed of resin and benzoic acid. Gum Resins are the hardened juices of certain plants, con- sisting of resin, gum, and volatile oil. Their proper solvent, therefore, is a mixture of alcohol and water, or common Oils. Alcohol 341 spirits. They are numerous, and many of them are valuable medicines; among them are aloes, asafoRtida, galbanum, gamboge, myrrh, and guaiacum. Caoutchouc^ or India rubber, is obtained from four species of trees, two of which grow in South America, and two in the East Indies. It is usually black, but when not darkened by smoke, is of a whitish color. It burns with a bright flame ; is insoluble in water or alcohol. It is soluble in ether, the essential oils, etc. If a bag of it be soaked in ether, it will become soft and gelatinous before dissolving, and in that state may be blown out into a very large and thin bag. The most useful solvent of caoutchouc is a dark, volatile liquid, obtained by the careful distillation of caoutchouc itself; about four fifths of the solid pass over in this liquid form. Wax. Wax is found in the pollen or dust of flowers, on some leaves as a kind of varnish, and especially on the berries of the wax-plant, (myrica cerifera.) As bees deposit wax, when fed only on sugar, beeswax is an animal product. Wax is insoluble in water, and is sparingly dissolved by alcohol and ether. It is composed of two principles, cerin and myricin. Creosote. This substance exists in tar, and in pyroligne- ous acid. It is a colorless, oily liquid, with an odor like smoked meat. It has a burning taste, followed by sweetness. Its most remarkable property is that of preserving meat. The antiseptic properties of smoke, and crude pyroligneous acid, appear to be owing to this substance. It is soluble in 80 parts of water, and freely in alcohol. Insects and fish are killed by the aqueous solution. It is said to be useml as a cure for toothache, ulcers, etc. SECT. 5. SPIRITUOUS AND ETHEREAL SUBSTANCES. Alcohol. C 4 H 5 O + HO. 46. This substance is the prod- uct only of fermentation, and is never found ready formed in any vegetable substance. It is obtained by the distillation of ardent spirits, of which it constitutes 50 per cent. After 29* 342 Vegetable Chemistry. a second distillation, it still contains some water, most of which may be removed by carbonate of potassa added in a dry state. Common alcohol has a specific gravity of about .86, but when freed from water, of .82. The purest alcohol boils at a temperature of 170 Fahr., is highly inflammable, burning with a very pale blue, but hot flame. No smoke is produced in its combustion, and hence it is of great utility for lamps in a laboratory, various kinds of apparatus being thus conveniently heated, and not soiled with smoke. Al- though exposed to a temperature of -176 Fahr., pure alco- hol has never been frozen. Alcohol combines with water in every proportion ; with an tqual quantity of water, it constitutes spirit of the Jirtt proof. The density of this is about .92. The density will be in proportion to the weakness of the spirit. Proof spirit is very useful, in cabinets of natural history, for the preser- vation of specimens of fishes, reptiles, etc. Its effects upon the animal system, as a poison, are well known : it has the power of passing into the circulation undigested, and ir- ritates all the organs with which it comes in contact. The stronger wines contain 18 to 25 per cent., and the weaker from 12 to 17 per cent. In wines it appears to have less in- toxicating power than in ardent spirits, which may be owing to its chemical combination with mucilaginous and saccha- rine matters. As a solvent, alcohol is useful. Many vegetable princi- ples, not soluble in water, are freely so in alcohol. Both mineral and vegetable alkalies are soluble, but it does not dissolve the earths, or other metallic oxides. Ethers. Most of the stronger acids, when heated with alcohol, yield a very volatile, inflammable liquid, called ether. Different kinds are formed from different acids. Sulphuric Ether (C 4 !!^)) is the most common. It is pre- pared by boiling equal weights of alcohol and sulphuric acid ; the vapor of ether passes over, and is condensed in' a vessel surrounded by ice-cold water. Ether. Coloring Matters. 343 The specific gravity of pure ether is .7; as commonly sold, .74. It boils at the temperature of blood heat ; in a vacuum, it boils at -40 Fahr. It congeals at -46 Fahr. It is slightly soluble in water, but combines with alcohol in all proportions. Hydrochloric Ether (C 4 H 5 C1) is formed by the action of hydrochloric acid on alcohol. It burns with an emerald- green flame, without smoke. Nitrous Ether (C 4 H 5 O+NO y ) is produced by the action of equal quantities of nitric acid and alcohol, and resembles sulphuric ether, but is more volatile. Oxalic Ethtr (C 4 HfO-f C 2 Q3) is formed by mixing 1 part of alcohol, 1 binoxolate of potassa, and 2 of SO 3 . CEnanthic Ether (C^^O + C^H^O 2 ) gives to wines their peculiar odor, and is obtained in the distillation of wine, as an oily liquid, which is a mixture of oenanthic ether with ex- cess of cerumthic acid. The ether is separated by distillation. It produces intoxication when inspired. Pyroxylic Spirit (C2H 3 O + HO. 32) is a kind of ether formed by heating wood, and comes over with the aqueous liquid. It has an alcoholic and aromatic odor, and is em- ployed by hat-makers, for the purpose of dissolving shellac and mastic, to stiffen and render hats water-proof.* SECT. 6. COLORING MATTERS. The most common colors in the vegetable kingdom are green, yellow, blue, and red. The greater part of the infinite diversity of colors consists of different shades or mixtures of these. The coloring matter of plants is usually diffused through other proximate principles. All vegetable colors are destroyed by chlorine, and usually changed by acids or alkalies. Lakes are insoluble compounds of coloring matter with alumina, or oxide of iron or of tin. * For a complete description of ethers, see Thompson, Org. Bodies. 344 Vcgttable Chemistry. Process. Dissolve alum in a colored solution, and, on add- ing an alkali, (as potassa,) alumina will be precipitated, and, at the moment of separation from the alum, will combine with the coloring matter. In dyeing, some colors have a sufficient affinity for the fibre of the cloth to remain fast on a mere immersion of it. In many cases, however, this is not sufficient, and the color would be removed by washing. A third substance is intro- duced, which, having an affinity both for the coloring matter and the cloth, fixes the former permanently to the latter. This third substance is called the mordant or basis : those which are in common use are, Alumina in alum, oxide of iron in copperas, and chloride of tin, which is converted into the oxide. All the colors of dyed stuffs are produced from the four blue, red, yellow, and black. />'/// Dyes. Indigo is the most important of these, and is obtained from several species of a genus of plants which arc cultivated in America and Asia. The plants are fermented and beaten in water, at the bottom of which the indigo sub- sides. Common indigo contains, in addition to its peculiar blue, a red and a brown coloring matter, with some gluten. Pure indigo sublimes at 550 Fahr., and condenses in acic- ular crystals. It is insoluble in. water, and but slightly soluble in boiling alcohol; it is soluble in sulphuric acid. It indigo be put into a tube with three times its weight of green vitriol, and an equal quantity of slacked lime, with water, the protoxide of iron will be precipitated by the lime from the green vitriol, and the indigo will be de-oxidized by it, and become yellow. Dyers dip their cotton cloth into it in this condition, and by exposure to air the cloth becomes perma- nently blue. Red Dyes. The most common substances for red dyes are cochineal, lac, Archil, madder, Brazil wood, and logwood. Cochineal is obtained from an insect which feeds upon the leaves of several species of the cactus, and which is supposed to derive this coloring matter from its food. It is very solu- ble in water, and is fixed on cloth by means of alumina or Fermentation. 345 oxide of tin. Its natural color is crimson, but when jaitar- trate of potassa is added to the solution, it yields a rich, scarlet dye. The beautiful pigment called carmine, is a lake made of cochineal and alumina or oxide of tin. T. Archil is obtained from a lichen which grows in the Canary Islands. Litmus, which consists of red coloring matter and alkali, is prepared from it. Madder is the root of the rubia tendorum, and employed for dyeing the Turkey red. Yellow Dyes. The principal are quercitron bark, turmeric, saffron, and fustic. Black Dyes. These are prepared from the same ingre- dients as writing ink. The addition of logwood and acetate of copper gives a blue-black. SECT. 7. FERMENTATION. I Many vegetable substances, when exposed to warmth and moisture, undergo spontaneous changes, and the process is called fermentation. It is most commonly observed in sub- stances containing gluten, starch, gum, or sugar. In different stages of the process, sugar, alcohol, and acetic acid are formed, and finally, there is a total dissolution of the sub- stance. These stages of the process are called the sac- charine, vinous, acetous, and putrefactive fermentations. Saccharine Fermentation. - Starch only is subject to this kind of fermentation. The quantity of sugar produced*equals in weight half of the starch employed. The ripening of fruits has been regarded as a kind of saccharine fermentation, in which the acid of the green fruit is converted into sugar ; this change is caused by heat, not by the vitality of the plant. Vinous Fermentation. When sugar with water, and yeast or some other ferment, is exposed to a warm temperature, the sugar is converted into carbonic acid gas and alcohol, in nearly equal weights of each. As starch is convertible into sugar by fermentation, if the process be continued under the above conditions, it will be converted into alcohol and car- bonic acid. All vegetable bodies contain some substances 346 Vegetable Chemistry. which act as a ferment, and therefore, by the addition of moisture and regulation of the temperature, various kinds of grain containing starch, and of ripe fruits containing sugar, will undergo the vinous fermentation. Thus cider is formed from apples, and beer from grain. To obtain ardent spirits. the fermented liquor is heated, and the ajcohol passes over by distillation. In the fermentation of bread, the saccharine matter of the flour is resolved into alcohol and carbonic acid gas. The latter causes the dough to rise, and the former is entirely ex- jv -11 ( M! by the heat of baking. A company in London was formed for collecting the spirit emitted by the baking of bread ; if the fermentation of dough be continued, it under- goes the change next described, and becomes sour. Acetous Fermentation. Any liquid which has undergone the vinous fermentation, or pure alcohol with water and yeast, exposed to the air in a warm place, undergoes a change, in which oxygen is taken from the air, and carbonic acid thrown off. In place of alcohol, acetic acid is found in the liquor. Thus cider becomes sour by age, if exposed to the air, and at length is converted into vinegar. In France, wine is con- verted into vinegar, and in England, an infusion of malt. Acetic arid is often formed in the spontaneous decomposi- tion of vegetable substances without sugar. I ir these < the process is quite different from the acetous fermentation, properly so called. JPutrefuit'ri- /'///// nhttion. Many vegetable principle the acids, oils, resins, and alcohol, are not subject to putrefar- tion ; those which contain oxygen and hydrogen in the pro- portion to form water, and especially those in which nitrogen exists, are subject to this change ; moisture, and a moderately warm temperature, are essential to the prore-s. which is also promoted by air ; water serves to loosen the particles of the substance, and enables them to act freely upon each other. The products of vegetable putrefaction are carbonic acid gas, and light carbureted hydrogen. In stagnant waters, which contain decaying plants, these gases often rise in bub- Germination. 347 bles, especially if the bottom be stirred. Usually, light car- bureted hydrogen is the most abundant gaseous product. In plants, which contain nitrogen, ammonia is generated ; water is the principal liquid product, and vegetable mould, consisting of charcoal, a little oxygen and hydrogen, the solid product. SECT. 8. GERMINATION. Germination refers to the process by which a new plant originates from the seed. The seed consists of two parts. The germ, which is endowed with the vital principle, and the cotyledons, or seed-lobes, which furnish nourishment to the plant before it can derive it from the earth. The germ is composed of the radicle, or that part which descends into the ground, and forms the root, and the plumula, which rises into the air, and forms the stem of the plant. The three conditions necessary to the germination of the plant, are moisture, a certain temperature, and oxygen gas. Dry seeds will riot germinate, or, if moist, germination will not take place at 32, nor at the temperature of boiling water, which deprives the germ of its vitality. The most favorable temperature is from 69 to 80, varying with the nature of the plant. Air is also necessary to germination ; for if seeds are buried deep, excluded from the air, they will never pass through this process. In the malting of barley, the process of germination may be accurately studied. The malting is done by exposing the grain to moisture, warmth, and air, until it begins to germinate, and then drying il in a kiln, where the temperature ranges from 100 to 160, or more. The chemical changes which take place in this process, are the following : The hordein, an insoluble substance, is converted into starch, gum, and sugar, \vhich are soluble and very nutritive substances, easily absorbed by the radicle of the plant ; at the same time, oxygen gas is consumed, and carbonic acid gas is given off. 348 Vegetable, Chemistry. Growth of Plants. There are many points of resemblance between the growth of plants and of animals; and also many points in which they differ. The chemical changes which the sap undergoes, by what is called the respiration of plant*, is probably very analogous to what takes place in the blood of animals ; with this difference, however, that animals cpn- sume oxygen, and throw off carbonic acid, while vegetables absorb carbonic acid and yield oxygen gas, provided, in the latter case, they are exposed to sunshine. In the night, the reverse often takes place; light seems necessary to the color- ing of plants, and to their health and perfection. Food of Plants. Plants derive their food, for the most part, from the earth. The soil generally consists of siliceous earth, clay, lime, and sometimes magnesia, mixed with the remains of animal and vegetable substances. The watt T passes through it, and dissolves the salts contained in it, ;mnt. When plants are burned, their ashes contain various salts which must have been derived from the earth. The peculiar vegetable substances which are formed from sap, appear to. be under the control of the vital principle, over which the ordinary agents of chemical changes have but little power. Animal Chemistry. 349 CHAPTER V. ANIMAL CHEMISTRY. With the exception of the oils, animal substances usually contain a large portion of nitrogen, and have a strong ten- dency to putrefaction. Their proximate principles are much less numerous than those of vegetables. In addition to car- bon, hydrogen, oxygen, and nitrogen, sulphur, phosphorus, iron, earthy and saline matters are usually present in animal bodies. SECT. 1. PROXIMATE PRINCIPLES NEITHER ACID NOR OLEAGINOUS. Fibrin. This principle is the basis of the muscles, and is found abundantly in the blood. It is a white, insipid solid when pure, and easily putrefies. When subjected to the action of nitric taid, it throws off a large quantity of nitrogen, and with acetic acid forms a jelly. Albumen. Albumen exists in a solid state in the skin, glands, and vessels, and in a liquid state in the serum of blood, the fluid of dropsy, and the white of eggs. The latter substance consists almost solely of it. When liquid, it is coagulated by heat, as in the boiling of an egg, or by alco- hol and the stronger acids. Corrosive suhjimate is a very delicate test, producing a milkiness in water, which contains ffirW albumen. Gelatin. This substance is abundant in the solid parts of animals, in the skin, cartilages, membranes, and bones. It is easily soluble in boiling water, and forms a bulky jelly on cooling. One part in 100 of water, will render the whole solid when cool. The jelly is a hydrate of gelatin; and, if the water be expelled by a gentle heat, it may be preserved for any length of time. This is glue, which is prepared from the ears, skins, and hoofs of animals. Isinglass is the purest variety, prepared from the sounds offish. 30 350 Animal Chemistry. Osmazome exists in the muscular fibres. It is very insolu- ble, and is supposed to give to broth its peculiar flavor. SECT. 2. ANIMAL ACIDS. Many acids are found in animals, which are found also in the mineral and vegetable kingdoms ; such are the sulphuric, hydrochloric, phosphoric, and acetic acids. Those which are peculiar to animals, are very few, and are derived chiefly from urine, or from oils and fats ; of the latter are stearic, oleic, and margaric acids. Formic acid is a remarkable acid, found in ants, and is ejected by them when they are irritated. SECT. 3. ANIMAL OILS AND FATS. These substances are very similar to the vegetable oils, and may be used either in the manufacture of soap, or for giving light. Train Oil is obtained from the blubber of the right whale, and is much inferior for lights to spermaceti. Spermaceti Oil is obtained from the blubber of the sperm whale, and from a large cavity in the head, from whirh twelve or fifteen barrels of liquid oil are sometimes dipped out. This substance is strained through stout bags, which are subjected to a strong pressure. The solid which remain- is spermaceti f of which candles are manufactured, and the liquid is the spermaceti oil. As the oil is more liquid in hot weather, summer-strained oil contains more spermaceti, and b given quantity will therefore produce more light, and burn less freely than winter-strained oil ; the latter is usually pre- ferred, as giving a clearer light, and as being less affected by cold, but it is much less economical. Hog's Lard and Suet are well-known substances, differing much in respect to their point of fusion. Animal oils and fats are not proximate principles, but con- Complex Animal Substances. 351 sist chiefly of stearine and margarine, which are solid at common temperatures, and olcinc, which is liquid. Soaps. When any of the animal or vegetable oils or fats are boiled with a solution of potassa or soda, the former are converted into margaric, oleic, or stearic acids, and another principle called glycerine. The acids combine with the ul kali, and form soap. The compounds which they form are soluble in pure water, but in solutions containing salts of lime, oxide of lead, and many other metallic compounds, they combine in preference with these oxides, and form in- soluble compounds. Hence hard water, containing salts of lime, curdles soap. Ambergris, found floating on the ocean, is supposed to be a concretion formed in the stomach of the sperm whale. SECT. 4. COMPLEX ANIMAL SUBSTANCES. Blood. Blood consists of a liquid, through which are diffused red globular particles. The liquid portion consists of water, holding in solution fibrin, with albumen, and saline and oily matters. When set at rest, it coagulates, forming a jelly. The red globules are also compound, containing fibrin and the coloring matter. In mammiferous animals, these globules are spherical ; but in birds, reptiles, and fishes, they are ellipsoidal. When blood is set at rest, it does not separate into the two parts above mentioned, but into a red coagulum called the clot and the serum, which is a yellowish liquid. The saline substances contained in the blood are carbon- ates, phosphates, and sulphates of potassa and soda. It con- tains also chloride of sodium, (common salt,) chloride of potassium, and sesquioxide of iron. More than j of the blood is water ; the coloring matter is in the ratio of 125 parts in 1000, and albumen, about 67 in 1000. The propor- 352 Animal Chemistry. tions vary somewhat, even in the same person, at different times. The following table, by M. Le Canu, represents the com- position of the blood as derived from two careful analyses : Water, 780.145 785.590 Fibrin, . . .*.-.'<>. . . 2.100 Coloring matter, . . %-, * .- . . 133.000 ll'.'.i.Ji; Albumen, . . " . .- . . , s " 65.090 69.4 15 Crystalline fatty matter, . . - .* >* ';' 2.43 4.300 Oily matter, 1 :Ut) Extractive matter soluble in water and alcohol, Al'uinicii mi:iliined with soda, . . . 1.265 Chloride of* sodium, . . . " of potassium, . . CarbonaU>s5, . . 8.370 7.304 Phosphates V of soda and potansa, Sulphates ) Carbonates of lime and magnesia, Phosphates of lime, magnesia, and iron, . 2.100 1.414 Peroxide of iron. Loss, .;.... . . " . . 2.400 2.586 1000.000 1000.000 ron,? The changes which are effected on the blood by respira- tion, are due to the oxygen of the atmosphere. The dark blood of the veins enters the lungs, and, being there exposed to the action of the air through a thin membrane, absorbs oxygen, throws off* or forms carbonic acid gas, and passes into the arteries with a bright red color. A large quantity of carbonic acid is emitted by the lungs, and hence the ne- cessity of a free circulation of air in small or crowded room.-. Animal Heat. There is a striking analogy between the process of combustion and respiration. In both cases, oxy- gen is consumed, and carbonic acid produced. This fact led Dr. Black to infer that the heat generated in the animal sys- tem was derived from the change which takes place in the lungs. That the development of animal heat is dependent upon respiration, is a matter of easy demonstration; but how the effect takes place, has not been satisfactorily explained. In those animals which consume a small quantity of oxygen, the temperature of their bodies varies with the surround inr medium, and are called cold-blooded ; but in those that con- Complex Animal Substances. eume a larger quantity of oxygen, the temperature is nearly uniform, whatever be the temperature of the medium. They are hence called warm-blooded. The temperature of the same animal varies often, according as the respiration is slug- gish or rapid. To account for animal heat, Dr. Crawford proposed the first consistent theory, which is founded on the supposition that the blood, when purified by the oxygen of the air, has its capacity increased for caloric; and hence the heat pro- duced in the lungs by the consumption of the oxygen, enters into an insensible state, in the arterial blood. As this blood circulates through the system and enters the veins, it loses its capacity, and gives out its caloric. But Dr. Davy denies that there is any difference between the capacity of venous and arterial blood. If, however, we suppose that the oxygen does not combine with the carbon in the lungs, but in the course of circulation, there would be heat developed in all parts of the system; and this view would account for the facts, irre- spective of the different capacities of the two kinds of blood. The influence of the vital principle, doubtless, has much to do, both in the development and preservation of animal heat. The nerves have been supposed also to possess a specific power of generating heat ; but, whatever be the cause, it is evident that the arterialization of the blood does not account for all the heat of the animal system, from the fact that a healthy animal imparts more heat to surrounding bodies, than could be produced froin this source alone. Saliva. This liquid contains only seven parts of solid matter in a thousand. It contains chloride of potassium, sulphate, phosphate, acetate and carbonate of potassa, with some other salts. It forms a soft, pulpy mass with the food in mastication, preparing it for more easy digestion. Gastric Juice. This fluid taken from an empty stomach has a saline taste, and is neutral. But when any substance enters the stomach, acid is secreted. Both hydrochloric and acetic acids are formed. All nutritious substances are dis- solved by this juice, and converted into a pulpy mass caJled 30* 854 Animal Chemistry. chyle. It does not act on living substances, or the stomach itself would be dissolved, as sometimes is the fact after death. Its solvent power is due to the acids, which are greatly aided by the temperature of the stomach. By taking magnesia, the acids are neutralized, and the digestive power suspended for the time. Bile. The bile is a yellow or greenish, nauseous liquid, of which I are water, and the remainder a peculiar bitter principle, called picromal, with resin, and several salts. Th< bile stimulates the intestinal canal, and assists in converting the chyme into chyle. Chyle. This is a white fluid resembling milk. It contains about 90 per cent, of water ; of the other constituents, albu- men is most abundant. Milk: This liquid is well known to consist of cream, curd, and whey. 100 parts of cream, of specific gravity 1.0244, contain only 4.5 parts of butter; of the remainder, 92 are whey, and 3.5 curd. The coagulation in sour milk is produced by the generation of acetic acid, which, in com- mon with acids generally, separates the curd from the whey. The same effect is caused by rennet prepared from a c:ilf s stomach, which is impregnated with the gastric juice, and therefore contains acid. Milk is of course curdled when taken into the stomach. Lymph is a peculiar; limpid, transparent liquid, which moistens the cellular membrane, and collects abundantly in some dropsical affections. It consists chiefly of water, with hydrochlorate of soda and albumen. The humors of the eye contain more than 80 per cent, of water ; the other ingredients are albumen, muriate and acetate of soda, pure soda, and an animal matter like curd, which gives it a milky appearance. The tears contain pure soda, chloride of sodium, and phos- phate of soda, with water, and an animal matter analogous to albumen. Mucus is a fluids ecreted by the raucous surfaces, as the nose. Complex Animal Substances. 355 Pus is a liquid matter secreted by an inflamed and ulcera- ted surface. Its characteristic ingredient resembles albumen. Sweat is the vapor which constantly passes off from the skin, and consists mostly of water, mixed with a little jnuriate of soda, and free acetic acid. Urine differs from most animal fluids in serving no ulterior purpose in the animal economy. It is an excretion consisting of substances which would prove injurious to life and health. The urine is separated by the kidneys from the blood, and consists of a great variety of substances, such as water and urea, which are the principal, uric acid, lactic acid, lactate of ammonia, mucus, sulphates of potassa and of soda, phos- phates of soda and of ammonia, muriates of soda and of am- monia, earthy matters with a trace of fluate of lime, and sili- ceous earth. Eggs. The shell of an egg is about -fa, the white -ft, .and the yolk T 3 ^ of the whole. The shell consists chiefly of -carbonate of lime ; and the white, of albumen, with a little sulphur. The yolk contains phosphorus, which supplies phosphoric acid for forming the bones of the chicken. Bones. Bones contain about of animal matter, of phosphate of lime, -^ of carbonate of lime, with a little fluoride of calcium, and some other salts. Teeth have the same com- position, but the enamel contains 78 per cent, of phosphate of lime. The shells of crustaceous animals, as lobsters and crabs, consist of carbonate and phosphate of lime, with anir mal matter ; but the shells of molluscous animals, or true shells, as of the oyster, snail, etc., consist almost entirely of carbonate of lime and animal matter. Horn differs from bone in containing only a trace of earth. The composition of the nails, hoofs, and cuticle of animals is similar to horn. Tendons are composed almost wholly of gelatin. The true skin has nearfy the same composition. Membranes and ligaments contain in addition some substance which is insoluble in water, and is similar to coagulated albumen. Hair contains a peculiar animal substance, insoluble in water at 212, but soluble in a solution of potassa. It also 356 Analytical Chemistry. contains an oil, which gives the peculiar color of the hair, sulphur, upon which the nitrate of oxide of silver acts in stain- ing it, together with silica, iron, manganese, and carbonate and phosphate of lime. Woo/ and feathers are similar in composition to hair. Silk is covered with a peculiar varnish, which amounts to about 23 per cent. Muscle. The lean flesh of animals consists essentially of fibrin, with numerous other ingredients, such as albumen, gelatin, a peculiar extractive matter called osmazomc, fat, and salts. CHAPTER VI. ANALYTICAL CHEMISTRY. It is the object of analytical chemistry to point out the method of separating compound bodies into their simple elements. As the subject is extensive, a few things only will be inserted here, in order to give the student an idea of the nature of the procees. SECT. 1. ANALYSIS OF MIXED GASES. 1. Gaseous Mixtures containing Oxygen. f^ gt 102. The best process by which oxygen gas may be withdrawn from gaseous mixtures, is by . means of hydrogen gas. In case of the air, a given portion is taken, and rather more hydrogen added than is sufficient to com- bine with the oxygen. The mixture is then introduced into a strong glass tube, or eudi- ometer, (Fig. 102,) over water or mercury, and exploded by the electric spark. The total diminution in volume, divided by three, will give the quantity of oxygen present. Instead of exploding the gases, they may be made to combine slowly, by introducing into the mixture platinum sponge. Analysis of Minerals. 357 2. Gaseous Mixtures containing Nitrogen. As the air contains only oxygen and nitrogen, when other substances are withdrawn, if its oxygen is determined, the quantity of its nitrogen may be easily known. The only mode of ascer- taining the quantity of nitrogen in any mixture, is to vvith- carbonate of lead by liquid ammonia, which holas it in solution. 3. Orr.s- of Mercury are mixed with iron-filings or lime, and exposed, in an iron retort, to a strong heat; when the mercury will distil over. 4. Ores of Zinc may be boiled in nitric acid to dry ness, and the pro- cess repeated. If iron is present, it will be peroxidated. and dilute nitric acid will dissolve out the zinc ; filter the solution, and add liquid ammonia in excess ; the lead, if present, will be precipitated, and the zinc will remain in solution. The oxide of zinc is obtained by boiling this solution to dryness. 5. Ores of Tin. As these ores usually contain silica, they must be first treated like an earthy mineral not soluble in acids. The tin will be detected by forming a purple solution with the chloride of gold. 6. Ores of Iron. The peroxide of iron is first rendered soluble by heating it for an hour with one eighth of its weight of powdered char- coal. The black oxide is soluble in dilute hydrochloric acid. If phos- phate of iron is present, it may be detected by adding to the hydrochloric solution 10 parts of water, (which has been boiled, to separate the air,) placing it in a bottle corked tight, and set aside for 6 or 8 days, when the phosphate of iron will be precipitated. The filtered solution may contain oxides of iron, manganese, and zinc, all of which are thrown down by carbonate of soda. The oxide of zinc may then be separated by ammonia, and the oxide of manganese by acetic acid. The oxide of iron will then remain, and, after being ignited, will contain 72 per cent, of the pure metal. 7. Ores of Copper are boiled dry with five times their weight of sul- phuric acid. The sulphate of copper which is formed is dissolved by water, and the metallic copper precipitated by a plate of clean iron. 8. Ores of Silver are dissolved by nitric acid. Immerse in the solu- tion a plate of polished copper, and the silver will be precipitated upon it, if no lead is present. Common salt will throw down the chloride of silver. 9. Ores of Gold and Platinum are dissolved in nitrohydrochloric acid ; the solution is then evaporated until nitrous acid fumes cease to appear, and the odor of chlorine is perceptible ; the product is dissolved in water, and a solution of hydrochlorate of tin added, when a purple precipitate will be thrown down, if gold is present. If platinum is in the mixture, it may be precipitated by hydrochlorate of ammonia. When the solution contains gold with other metals, the sulphate of the protoxide of iron precipitates the gold with the palladium, mercury, and silver, if present. As silver is most frequently present, common salt should be added previous to the sulphate of iron, to precipitate it. Earthy Sulphates. The sulphate of lime is easily analyzed by boil- ing it for fifteen or twenty minutes in a solution of twice its weight of carbonate of soda. The carbonate of lime and sulphate of soda are 360 Analytical Chemistry. formed by doable decomposition. The sulphate of soda is then de>- composed by chloride of barium, and the carbonate of lime analyzed in the usual way.* SECT. 3. ANALYSIS OF MINERAL WATERS. The purest water is obtained by distillation. Rain water, or that from fresh fallen snow, is next in purity. Well and spring water contain some salts, which are de- rived from the soil through which the rain water j> hence the purity of water will depend upon the nature of the soils. If it is filtered through primitive strata, such as ir;m- ite, it will contain few salts, but if through secondary - such as limestone and gypsum, it becomes impregnated with various other substances, and is mineralized. Lame renders it hard. The different kinds of mineral water are ttridulmtt, ti/ka- line, chalybeati, fiilp/inrtttd. .^i/iin , and si/icrnus s/irin^s. 1. In acidulous springs, of which those of Saratoga and Seltzer are examples, the acidity is due to tin- < -arhonic acid with which their waters are impregnated; they frequently contain protoxide of iron, carbonates of lime, magnesia, and other saline compounds. The carbonic acid is easily expelled by heat, and may be collected over mercury. 2. Alkaline springs are very rare; they generally contaiir* a free or carbonated alkali. :*. Chalybeate springs. These waters are character i/.ed by styptic, inky taste, and by striking a black color with ini',- sion of gall-nuts. The iron is either combined with hydnv- chloric and sulphuric acids, or exists in the form of proto- carbonate, held in solution by free carbonic acid. On exposure to the air, the protoxide is oxidized, and the hy- drated peroxide subsides as an ochreous deposit, which is commonly found in the vicinity of chalybeate springs. T. 4. Saline springs owe their properties to saline compounds, such as sulphates and carbonates of lime, magnesia, and so- da, and the chlorides of calcium, magnesium, and sodium. .In the analysis of saline springs, the first object is to ascer- tain the nature of the ingredients. Hydrochloric acid is detected by nitrate of oxide of silver, sulphuric acid by chlo- ride of barium; and if an alkaline carbonate be present, the precipitates will contain a carbonate of oxide of silver, or of baryta. Lime and magnesia may be detected, the former by * For other sulphates, see Turner, p. 241. Test Tubes, 361 oxalate of ammonia, and the latter by phosphate of ammonia. Potassa is known by the action of chloride of platinum. To detect soda, the water should be evaporated to dryness, the deliquescent salts removed by alcohol, and the matter insolu- ble in that menstruum taken up by a small quantity of water, and allowed to crystallize by spontaneous evaporation. The salt of soda may then be recognized by the rich yellow color which it communicates to flame. If the presence of hydri- odic acid be suspected, the solution is brought to dryness, the soluble parts dissolved in two or three drachms of a cold so- lution of starch, and strong sulphuric acid slowly added. T. Sulphurated springs are characterized by their odor, and by the brown precipitate, which a salt of lead or silver occa- sions. This is owing to the hydrosulphuric acid gas which they contain. The quantity of gas is ascertained by boiling the water, which expels it. To detect Hydrosutphuric Jlcid. Take a flask, with a tube bent twice at right angles, one end of which dips into a solution of acetate of lead. (Fijr. 104.) Introduce the water into the flask, and apply heat until it boils. The gas will be driven oft, and decompose the acetate, forming a sulphuret of lead; filter, dry, and weigh. 16.1 parts will be sulphur, and 103.6 parts lead, -fa part of the weight of the sulphur, added to its weight, will give the weight of the hydrosulphu- ric acid If the water, after being boiled, yields a black precipitate, with acetate of lead, acetic acid must be added, and the liquor boiled, and the gas passed through the acetate, as before. The mode of estimating the solid matter held in solution in mineral waters is simply to boil the whole to dryness, and weigh the residue. The different kinds of matter are then detected in the usual way for analyzing other solid bodies. Fig. 104, Test Tubes. For the purpose of test- ing substances in solution, test tubes (Fig. 105) are very convenient. They are glass tubes, from 3 to 12 inches in length, and from J to 1 inch in diame- ter, open at one end, while the closed end is so made that the liquid may be heat- ii Fig. 105. 30-2 Analytical Chemistry. ed as in a retort. A small quantity of any solution may be examined in them with great facility, and they are especially convenient to form precipitates. These tubes may be placed upon a frame, as in the figure, and answer often the threefold purpose of retort, receiver, and test tube. Filtration. When a solution has been prepared for exam- ination, it ought to be perfectly clear. If it appears muddy, it must be subjected to filtration ; that is, it must be passed through a paper filter, by which means it is separated from solid matters, which make it appear opaque. As this oj>< -ra- tion frequently occurs in chemical analysis, and in ni manipulations, it is important to understand the mode of per- forming it. The filtering paper should contain no glazing or sizing, and should be folded in the following form : 1. Take a square piece of paper, and fold it like a sheet of paper, that is, so as to bring two corners together ; then fold it so as to bring four corners together; cut off the corner-. and by opening the folds it will have the form of an inverted cone, and may be placed in a funnel. 2. But for filtering rapidly, the filter may be folded in the following form : Fold the pa- per in two, as before ; then (Fig. 106) fold 10 upon 2, then 10 upon 6, then 1 10 upon 1 8, then 2 upon 8, then 2 upon 6, 2 upon 4, and 10 upon 4 : this will produce 7 folds, all on one side of the pnper. Slake, now, folds between each of these, so as to raise ribs on the opposite side of the paper. Cut out the projecting corners, to give the whole acircularshape ; open it, and form it into a cup. (Fig. 107.) 100. 107. Filtration, 363 Fig. 108. The filter may then be placed in the funnel c, (Fig. 108,) and supported by a lamp-stand or a wood-stand, made for the pur- pose ; or it may be placed in the top of a tall jar. The liquid to be filtered is then put into it, and a vessel placed beneath to con- tain the liquid as it slowly passes through the paper. By this pro- cess, the solid and liquid parts are separated, and either may be examined in their separate st ;lr. : < If it is desired to estimate the quantity of solid matter, the filter must be weighed previous to placing it in the funnel ; and the solid matter, after being washed, by directing a fine stream of water upon it, until the water comes through taste- less, is dried and weighed : the difference of weight shows the quantity of solid matter. Supports of filters and vessels may be of iron wire, made into the form of a tri- angle. (Fig. 109.) Take three pieces of iron or copper wire, and twist the ends as in the figure, leaving a triangular aperture : this may be placed upon the tops of jars and other vessels, or upon the rings of the lamp -stand, to support crucibles, evapo- rating dishes, retort*;, filters, &,c. Fig. 109. * For clicmicni manipulation, and blowpipe analysis, the student is referred to Griffin's Chemical Recieations. APPENDIX Wollaston's Synoptic Scale of Chemical Equivalent*.* The scale consists of a movable slider, with a seri< numbers upon it, from 10 to 320, on each side of whicli on the fixed part of the scale, are set down the names of va- rious chemical substances. The scale is founded on the constancy of composition in chemical compounds, the equivalent power of the quantities that enter into combinations, and the properties of a logo* metric scale of numbers. The numbers are so arranged, that at equal intervals they bear the same proportion to each other. The student \\ ill easily observe and understand this, by measuring a feu dis- tances upon the scale, with a pair of compasses, or even a piece of paper. If his paper extend from 10 to 20, it will also extend from 20 to 40, or from 55 to 110, or from 100 to 320. Whatever number is at the upper edge of the paper will be double at the lower. If any other distance l>r taken, the same effect will be observed. If, for instance, the paper extends from 10 to 14, then any other two numbers found at its upper and lower edge will be in the same proportion as these two numbers 10 and 14. Thus, make the upper num- ber 100, and the lower number will be 140. ' Now, supposing that the paper were cut of such a width that, one of its edges being applied upon the scale to the num- ber representing the equivalent of one body, the other should coincide with the number of the equivalent of a* second body ; then, upon moving the paper, wherever it was placed over the numbers, those at its upper and lower edges would still rep- resent the corresponding proportional quantities of the two bodies as accurately as at first, because the numbers at equal * The paper, by iU author, describing the scale, is inserted in the Philosophical Transactions for 1814. Appendix. 365 distances on the scale are proportional to each other. Thus, suppose the upper edge were made to coincide with 40 and the lower with 78, then the upper edge might be called sul- phuric acid, and the lower baryta; and this width once as- certained, the paper, wherever applied upon the scale, would show at its lower edge the quantity of baryta necessary to combine with the quantity of sulphuric acid indicated by its upper edge. ' It is evidently of no consequence whether the paper be moved up and down over the scale, or the line of numbers be moved higher and lower, to bring its different parts to the edges of the paper. And supposing the piece of paper just described to be pasted upon the side of the scale, then, by moving the latter, any of the numbers might be made to coin- cide with the upper or lower edge at pleasure, and conse- quently the quantity of sulphuric acid necessary to combine with any quantity of baryta, and vice versa, ascertained by mere adjustment and inspection of the scale. Or if, instead of referring to the separate piece of pap'er, marks were to be made on the side of the scale at 40 and 78, and named sul- phuric acid and- baryta, the same object would be attained, and the same method of inquiry rendered available. Other substances are to be put down upon the scale ex- actly in the same manner. Thus, the scale being adjusted until the number 40 coincides with the sulphuric acid already marked, then sulphate of baryta is to be written at 118, and thus its place is ascertained ; nitrate of baryta at 132 ; soda at {- ; sulphate of soda at 72 ; and a similar process is to be adopted with every substance, the number of which has been ascertained by experiment. The instrument, which in this state merely represents the actual numbers supplied by exper- iment, will faithfully preserve the proportions thus set down, whatever the variation of the position of the slider may be. It is therefore competent to change all the numerical expres- sions to any degree required, the knowledge of one only being sufficient, first by adjustment, and then by inspection, to lead to the rest. A few illustrations of the powers and uses of this scale will be sufficient to make the student perfect master of its nature and applications. Suppose that, in analyzing a mineral water, the sulphates in a pint of it have been decomposed by the addition of muriate of baryta, and the resulting sulphate of baryta washed, dried, and weighed ; from its quantity may 31* 366 Appendix. be deduced the exact quantity of sulphuric acid previously existing in the mineral water. Thus, if the sulphate of baryta amount to 43.4 grains, the slider is to be moved until that number is opposite to the sulphate of baryta, and then at sul- phuric acid will be found the quantity required, namely, 14.7 grains. In the same manner the scale will give information of the quantity of any substance contained in a gi\ en weight of any of its compounds; these having previously been deduced from experiment, and accurately set down on the table in the manner just explained. If it be desired to know how much of one substance must be used in an experiment to act upon the other, it is evident that the equivalent must be taken, and this may be learned from the scale. Suppose that a pound of sulphate of harm has been mixed with charcoal, and well heated, to convert it into a sulphuret, and that by the addition <>i nitric aci1 hundredth pans, or somewhat above fa of a pound of six -h acid, \vi!l be sufficient for the pound of sulphate of baryta operated with. If a certain weight of carbonate of baryta be required in that moist and finely-divided state in which it is obtained by precipitation, and in which it cannot be weighed, the racy of the quantity may be insured by taking the equivalent of dry muriate, or nitrate of baryta, precip !v an ex- cess of carbonate of potassa, and then washing off the which remain in solution. Suppose 100 grains of the car- bonate were required; by Bringing that number to carbonate of baryta, it will be found tint the quantity of dry muriate necessary will be 105.8 parts, and Ae quantity of nitrate 133.4 ; and if the quantity of carbonate of potassa necessary for this purpose be also required, it will be found, opposite the name of that substance on the scale, to be a little less than 70 parts, so that 5 or 10 parts more will insure a satis- factory excess. The second paragraph of Wollaston's description of this Appendix. 367 scale may be transcribed, as a further illustration of the powers of the instrument. " If, for instance, the salt under examination be the common blue vitriol, or crystallized sul- phate of copper, the first obvious questions are (1) How much sulphuric acid does it contain ? (2) How much oxide of copper? (3) How much water ? He [the analytic chemist] may not be satisfied with these first steps in the analysis, but may dosire to know further the quantities (4) of sulphur, (5) of copper, (6) of v oxygen, (7) of hydrogen. As means of nr-uiiiiKT this information, he naturally considers the quantity of various re-agents that may be employed for discovering the quantity of sulphuric acid, (8) how much baryta, (9) carbon- ate of baryta, or (10) nitrate cf baryta, would be requisite for this purpose. ( J 1 ) How much lead is to be used in the form of (12) nitrnte of lead; and when the precipitate of (13) sulphate of baryta, or (14) sulphate of lead, are obtained, it will be necessary that he should also know the proportion which either of them contains of dry sulphuric acid. He nny also endeavor to ascertain the same point by means of (15) the quantity of pure potassa, or (10) of carbonate of pot i-s i, requisite for the precipitation of the copper. He rnitrht also use (17) zinc, or (18) iron, for the same purpose; and he may wish to know the quantities of (19) sulphate of zinc, or (20) sulphate of iron, that will then remain in the solution." All these questions and points are answered by moving the slider until the number expressing the quantity operated with, coincides with sulphate of copper crystallized. 5, Water. Let it, for instance, be 100; this being brought opposite crys- tallized sulphate of copper, the information relative to all the above points, except the sixth and seventh, is supplied by mere inspection. The sixth may be supplied by subtracting (5) the quantity of copper from (2) the quantity of oxide of copper, or by halving the quantity at 2 oxygen, or taking the third of that at 3 oxygen. The seventh relates to the quan- tity of hydrogen in the 5 water present in the salt; this quan- tity of hydrogen does not come within the line of numbers, but may easily be obtained by doubling the quantity of water, or doubling the quantity of the salt used, which will then bring 10 hydrogen into the scale, and the half of this is to be taken as the quantity in 5 water, or in 100 grains of the salt. Putting, therefore, 200 to sulphate of copper, 10 hydrogen, is indicated as 17 parts nearly, when of course the half of this, 368 - Appendix. or 8.5 parts, is the quantity in 100 grains of the crystallized salt of copper. Whenever it thus happens that the number known or the number sought for is out of the scale, then some convenient multiplier of the numbers may be used. The most conve- nient method is to use the tens or the hundreds as units. <>r, what is the same thing, to consider for the time that dt< points are inserted between the units and the tens, or bet the tens and the hundreds of all the numbers on the scale. Thus, if it were required to ascertain how much magnesia and sulphuric acid were contained in a pound of crystallized sul- plnte of magnesia, no 1 exists upon the scale, and of course no fractions or small parts of 1 ; but imagine decimal points hetween'the tens and the hundreds, then 10 upon the becomes one tenth, 22 twenty-two hundredth*, 108 one, 220 two and two tenths, and so on. Bringing, therefore, 100 to crystallized sulphate of magnesia, it represents the 1 pound, ;mh burnt quicklime, and two scruples of camphor. Mix tin- whole intimately, and preserve it in small, wide-mouthed bottles, closely corked. When it is to be used, mix it with a little water, and apply it immediately. Irt. Diamond Cement for Glass or Porcelain. Dis.-rature Re- cording to Fahr. Ulantirity uf the vap. taking atmospheric preac. as unitj. ;>erntur ac- cording to Fahr. 1 212 13 380.66 u 233.96 ' 14 386.94 2 250..VJ 15 392.86 2} 263.84 16 898.48 3 275.18 17 403.82 3J 285.08 18 408.92 4 293.72 19 4i:*/> ft 300.28 20 418.46 5* 307.5 21 422.96* 5J 314.24 22 427.28 6 320.36 23 l:*1.42 6} -826.26 24 l:r>r,(; 7 331.70 25 480*34 7J 336.86 30 457.14 8 341.78 35 47*78 9 350.78 40 480..",!) 10 358.88 45 491.1 I 11 366.85 50 510.00 12 374.00 * Brande'i Jour. N. S. viii. 191. GLOSSARY. A. ABSORPTION, from absorbeo, to suck up; the power or act of imbibing a fluid. ACETIC ACID, from acetum, vinegar; the acidifying principle of com- mon vinegar. ACICULAR, from acus, a needle ; having sharp points like needles. ACTION, from uyu>, to move ; the effort by which one body produces, or endeavors to produce, motion in another. ADHESION, -IVE, from ad, to, and htereo, to stick; the tendency which dissimilar bodies have to adhere or stick together. AERATION, from <*/,, the air; the saturation of a liquid with air. AERIFORM, from aer, the air, and forma, a form; having the forr.i of air. AEROSTATION, from <*/,(>, the air, and 'ianjui, to weigh; primarily, it denotes the science of weights suspended in the air; but, in the modern application of the term, it signifies the art of navigating the air. AFFINITY, from ad, to, and finis, a boundary; relationship; the force which causes dissimilar particles of matter to combine together, so as to form new matter. ALBUMEN, -INOUS, from albumen, the white of an egg; an important animal principle. The white of an egg is albumen mixed with water. ALKALI, a soluble body, with a hot, caustic taste, which possesses the power of destroying acidity ; the term is derived from kali, the Arabic name of a plant, from the ashes of which one species is obtained, and the article al. AMALGAM, from aua, together, and yaut'co, to marry ; a chemical term, signifying the union of any metal with mercury, which is a sol- vent of various metals. AMORPHOUS, from a, not, and / t nw, to make rotten; possessing the power of preventing putrefaction. 32 374 Glossary. APPROXIMATE, -IVELY, from ad, to, and proximus, nearest; having affinity with ; bordering upon. AQUA REGIA, i.e., REGAL WATER, a mixture of nitric and muriatic acids; so called from its property of dissolving gold, held by the alchemists to be the king of the metals. Aftufco, from aqua, water; when prefixed to a word, denotes that water enters into the composition of the substance which it signifies. ARC, from arcus, a bow; a part of a curved line, as of a circle, ellipse, &e. ARMATURE, from armo, to arm ; a piece of soft iron applied to a load- stone, or connecting the poles of a horseshoe magnet. ASTATIC NEEDLE, from Uo*, a measure; an instrument for measuring the varying weight of the atinospln- n- BIBULOUS, from 6160, to drink; that which has the quality of drinking in moisture. BINARY, from big, twice ; containing two units. BOREAL, from boreas, the north ; northern. C. CALORIMETER, from color, heat, and mrtrvm, a measure ; an instnun. nt for measuring caloric. CAPILLARY, from capillus, a hair; resembling or having the form of hairs. CAPSULE, from rapsiila, a little chest; a small, shallow cup. CARBON, from carbo, a coal ; the chemical name for charcoal. CATALYSIS, from xaru, thoroughly, and irw, to loosen; an imaginary force, Which is supposed to assist the decomposition of some bodies, and the composition of others. CATHODE, from xaru, downward, and o.Vo, to shine; that which allows a passage to the rays of Tight. DIATIIKHM ANOUS, from Jiu, through, and StQuof, heat; that through which heat will pass is said to lx? diatheriuanous. DILATATION, from dtjfero, to bear apart ; the act of extending into greater space. DIMORPHOUS, from 4t<, twice, and MOQ!< ; an utter separation of particles. DISPERSION, -IVE, from di, in different directions, and sparge, to scat- ter ; the act of scattering. DISRUPTION, from dis, in different directions, and rumpo, to break ; the act of tearing asunder. DISSECTION, from disseco, to cut to piece* ; the act of separating into pieces. DISTILLATION ; separation drop by drop ; the process by which a fluid is separated from another substance, i>y first being converted into vapor, and afterward condensed drop by drop. DIVEM.KNT, from direlloy to tear asunder; that which causes sepa- ration. DIVERGENT, from rfi, in different directions, and rxrgo, to bend ; tend- ing to various parts from one point. DODECAHEDRON, from f*..,rUxu, twelve, and ov, electricity, and Ai/w, to loosen ; the act of decomposing bodies by electricity. ELECTRO-MAGNETISM ; magnetism produced by electricity. ELECTROMETER; an instrument for ascertaining the quality and quan- tity of electricity in electrified bodies. ELECTROPHORUS ; an instrument for producing electricity. ELECTROSCOPE ; an instrument for exhibiting the attractive and re- pulsive agencies of electricity. ELEMENT, -ARY, from clcmentum, an element; that which cannot be resolved into two or more parts, and contains but one kind of ponderable matter. ELLIPSE, from *x, deficiently, and A*//rw, to leave; one of the conic sections, formed by the intersection of a plane and a cone, when the plane makes a less angle with the base than that formed by the base and the side of the cone. EMPIRICAL, from *r, in, and TreiQuotiai, to make trial ; that which is made or is done as an experiment, independently of hypothesis or theory. EMPYREUMATIC, from >, in, and TTV^, fire ; having the taste or smell of burned animal or vegetable substances. ENDOSMOSE, from MtJor, within, and <$, the act of pushing; a flow- ing from the inside to the outside. EXPANSION, from expando, to open out; the enlargement or increase in the bulk of bodies, which is produced by heat. EXPERIENCE, from ezperior, to attempt, to try ; knowledge gained by observation. EXPERIMENT; something done in order to discover an uncertain or unknown effect. EXPLOSION, from ez, out, and plaudo, to utter a sound ; a sudden ex- pansion of an elastic fluid, with force and a loud report. F. FERRUGINOUS, from/errtm, iron; of iron. FILTER ; a strainer. FILTRATION ; the process whereby liquids are strained. FLEXURE, from flecto, to bend ; the act of bending; also, the bend or curve of a line or figure. Focus, -CAL, from/ocus, a fireplace ; a point in which a number of rays of light or heat meet, after being refracted or reflected. FORMULA ; a general theorem; it is called algebraic, logarithmic, &c. 7 according to the branch of mathematics to which it relates. FRICTION, from/rico, to rub; the rubbing or grating of the surfaces of 32* 378 Glossary. bodies upon one another ; also, the retarding force caused by this rubbing of surfaces together. G. GALVANISM, from Professor GALVANI ; current electricity is sometimes so called. GALVANOMETER; an instrument for measuring galvanism. GAS, -EOUS ; a term first introduced by VAN HELMONT ; a permanent, aeriform fluid. GELATINOUS, from gclo, to freeze ; resembling jelly. GONIOMETER, from /cor/a, an angle, and /UT^OI, a measure ; an instru- ment for measuring angles. ' * GRAVITATION, from gravis, heavy; the abstract power which draws bodies towards each other's centres. GRAVITY, from gravu, heavy ; the natural tendency of bodies to fall towards a centre. GRAVITY, SPECIFIC ; the relative gravity of a body considered with regard to some other body, which is assumed as a standard of comparison. H. HALO, from tiJwc, a crown ; a luminous circle, appearing occasionally around the heavenly bodies, but more especially about the sun and moon. HELIOGRAPHIC, from v*io?, the sun, and y, to twist round ; a screw or spiral. HEMISPHERE, from >oic, half* and o6$, moist, and , to consider ; an instru- ment for exhibiting apuroximatively the moisture of the atmos- phere. Glossary. 379 HYPO, from rno, under ; when prefixed to a word, denotes an inferior quantity of some ingredient which enters into the composition of the substance which it signifies. HYPOTHESIS, -TICAL, from i-v/>, under, and Ti&rju, to place ; a princi- ple supposed or taken for granted in order to prove a point in question. 1. IMPINGING, from impingo, to strike against; dashing against. INCANDESCENT, from incandesce, to grow white ; white or glowing with heat. INCIDENCE, from in, upon, and cado t to fall; the direction in which one body falls on or strikes another ; the angle which the moving body makes with the plane of the body struck, is called the " angle of incidence.'' INCREMENT, from incresco, to increase; the quantity by which any thing increases or becomes greater. INDUCTION, -IVE, from in, to, and duco, to lead; the process of reason- ing? D y which we are led from general to particular truths. INDUCTION, ELECTRICAL ; the effect produced by the tendency of an insulated electrified body to excite an opposite electric state in neighboring bodies. INDUCTOMETER ; an instrument for measuring electrical induction. INERTIA, from inertia, inactivity; the disposition of matter to remain in its state of rest or motion INFLAMMABLE, from in, and flamma, a flame ; capable of burning with a tlame. INFLECTION, from in, to, and facto, to bend. INSULATION, from insula, an island; when a body, containing a quan- tity of free heat, or of electricity, is surrounded by non-conductors, it is said to be insulated. INTEGRANT, from integer, whole, entire; those parts of a body which are of the same nature with the whole, are called integrant. INTERSTICES, from interstitium, a break or interval; the unoccupied spaces between the molecules of bodies. IRIDESCENT, from iris, the rainbow; marked with the colors of the rainbow. ISOMERIC, from i'oog, equal, and ufgog, a part; substances which con- sist of the same ingredients, in the same proportion, and yet differ essentially in their properties, are called isomeric. ISOMERISM ; that portion of chemical science which treats of isomeric substances. J. JUXTAPOSITION, from juxta, near, and pono, to place ; the placing of one thirig close to another. L. LAMINA, from lamina, a thin plate ; extremely thin plates, of which some solid bodies are composed. LENS, from lens, a bean ; properly a small glass in the form of a bean ; but more generally it means a piece of glass, or other transparent substance, having its two surfaces so formed that the rays of light, in passing through it, have their direction changed, and are made to diverge or converge, or to become parallel after diverging or converging. LEVIGATION, from tews, smooth ; the art of reducing to a light powder. Glossary. LIQUEFACTION, from liquefacio, to make liquid ; the process of convert- ing Into a liquid state. LITMDS ; a blue pigment obtained from the lichen rocella; it is a most delicate test of acids, which turn it red. LOADSTONE, i.e., LEADSTONE ; an ore of iron having magnetic properties. M. MAGNET, from Magnesia, a town in Asia Minor ; artificial magnets are small bars of steel or iron, which, when placed at liberty, turn one end to the north. MAGNETISM ; the peculiar property possessed by certain ferruginous bodies, whereby, under certain circumstances, they attract and re- pel one another according to certain laws. MAGNETO-ELECTRICITY ; electricity produced by magnetism. MALLEABLE, from malleus, a hammer ; that which is capable of being spread by beating. MAXIMUM, from maximum, greatest; the greatest value of a variable quantity. MECHANICS, from tuix av ',i a machine; the science which treats of the laws of the rest and motion of bodies. METALLURGY, from p'raJUor, a metal, and fyj-oi, a work ; the art of working metals, and separating them from their ores. MINERALOGY ; the science which treats of -bodies not being vegetable or animal. MOIRKE METALLIQUE, from molrtc, a watered silk ; when tin plates are washed over with a weak acid, the crystalline texture of the tin becomes apparent, forming a crystalline appearance, which has been called Moirce Metallique. MOLECULES, -AR, a diminutive from moles, a mass; the infinitely small material particles of which bodies are conceived to be a, eight, and 'ffya, a side; a solid figure con- tained by eight equal and equilateral triangles. OLEFIANT GAS, from oleum, oil, and Jio, to become ; a colorless, taste- less gas, which derives its name from its property of forming an oil-like liquid with chlorine. OPTICS, from onrouai, to see : that branch of natural philosophy which treats of vision, and of the nature and properties of light, and of the various changes it undergoes. ORGANIC MATTER, from ooyuior, an organ ; when matter possesses or- gans, or organized parts for sustaining living action, as animals and plants, it is called organic. ORGANIZATION ; construction in which the parts are so disposed as to be subservient to each other. OSCILLATION, from oscillor, to swing; the vibration or reciprocal ascert and descent of a pendulum. OXIDE ; a combination with oxygen, not being acid. OXIDIZABLE ; capable of being converted into an oxide. OXYGEN, from oi-ug, acid, and yervuw, to produce ; a colorless, aeriform fluid, which was formerly supposed to be the universal acidifying principle. P. PARABOLA, from Tra^u, parallel to, and j$uAAu>,toplace; one of the conic sections, formed by the intersection of a plane and a cone, when the plane passes parallel to the side of the cone. PARALLEL ; a term applied in geometry to lines and planes, which are every where equidistant from one another; straight lines, which, if infinitely produced, never meet, are called parallel straight lines. PARALLELOGRAM ; a four-sided figure, of which the opposite sides are parallel and equal. PARALLELOPIPEDON : a solid figure contained by six parallelograms, the opposite sides of which are equal and parallel. PELLICLE, a diminutive from pellis, a skin or crust ; a thin crust formed on the surface of a solution by evaporization. PENDULUM, from pcndeo, to hang; a heavy body so suspended that it may vibrate, or swing backward and forward about some fixed point, by the action of gravity. PERCOLATE, from prr, through, and coJo, to strain ; to strain through. PERM KATE, from perm?o, to pass through ; to penetrate. PERPENDICULAR ; the straight line which, standing upon another straight line, makes the adjacent angles equal, and consequently right angles, is said to be perpendicular to the line upon which it stands. PHENOMENON, from (pairouai, to appear; an appearance. PHILOSOPHY, -ICAL, from (/uAt'w, to love, and ooyia, wisdom ; the study or knowledge of nature or morality, founded on reason and expe- rience, the word originally implying " a love of wisdom." PHLOGISTON, from , to burn ; a name given by the older chemists to an imaginary substance, which was considered as the principle of inflammability. PHOSGENE, from oroe, time; performed in the same time. T. TACTILE, from tango, to touch; of or relating to touch. TANGENT, -IAL ; the line which touches a circle or any other curve, but does not cut it. TERNARY, from ter, thrice ; containing three units. TETRAHEDRON, from T'OOU, four, and Vuog, heat, and oxo/'ui, to view ; an instrument for exhibiting the powers of heat. TIRE; a hoop of iron used to bend and receive the felly of a wheel. TORSION, FORCE or, from turqueo, to twist; a term applied by Cou- lomb to denote the effort made by a thread which has been twisted to untwist itself. TRANSPARENT ; a term to denote the quality of a substance which not only admits the passage of light, but also of the vision of external objects. TRITURATED, from trituro, to thrash ; reduced to powder. TRUNCATION, from trunru*, cut short ; the cutting off a portion of a solid, as of the solid angle of a crystal. u. UNDULATION, from unda, a wave ; a formation of waves. UNIAXAL, from unus, one, and axis, an axis; having but one axis. V. VACUUM, Latin ; a space empty and devoid of all mattor. VENTILATION, from retitus, wind; the supply of fresh air. VERNIER; an instrument invented by Vernier; it consists of a small, movable scale, running parallel to the fixed scale of a quadrant or other instrument, and Raving the effect of subdividing the divisions of the instrument into more minute parts. VIBRATION, from vibro, to brandish ; the regular reciprocating motion of a, body, as of a pendulum, &c.; a motion to and frg. VOLUME, from volumen, a roll ; the apparent space occupied by a body. W. WEIGHT ; the pressure which a body exerts vertically downward in consequence of the action of gravity. Z. ZERO ; the numeral 0, which fills the blank between the ascending and descending numbers in a series. INDEX A Page. Acetate of alumina 327 ammonia 327 copper 326 iron 327 lead ' 326 mercury, tin, zinc 327 Acetous fermentation 34H Acid, acetic 326 antimonic 264 antimonious 264 apocrenic 331 arsenic 257 arsenious 255 azulmic 331 benzole 329 boracic 208 bromic 145 camphoric 330 carbazotic 331 carbonic ....?.... 176 chloric ; 139 chlorous 1 39 chloriodic 143 chlorocarbonic 181 chromic 259 citric 327 columbic 263 crenic 331 croconic 329 cyanic 1 88 cyanohydrosulphuric 200 cyanuric 188 elaidic 338 ellagic 330 fluosilicic 213 fluoboric 209 fulminic 188 gallic 328 hydriodic 156 hydrobromic 1 57 hydrochloric 154 hydrofluoric 157 hydroselenic 211 33 Acid, hydrosulphoeyanic. . .. 200 hydrosulphuric 197 hydrosulphurous ....... 199 hydrotelluric 263 hy drothionic . 1 1)7 hypochlorous 1 38 hyponitrous 165 hypophosphorous 202 hy posulphuric 1 94 hyposulphurous 192 indigotic 331 Todic 143 iodous 142 kinic 329 lactic 329 malic 327 margaric 330 manganic 240 meconic 329 mellitic 329 metagallic 330 metameconic 329 molybdic 262 moroxylic 330 mucic 330 muriatic . v 154 nitric 166 nitrohydrochloric 1 68 nitrohydrofluoric 1 69 nitrous 165 nitromuriatic 169 oxalic 325 oleic 330 paracyanuric 189 paraphosphoric 204 pectic 331 perchloric 140 permanganic. 240 periodic 143 phosphoric 203 Acidulous springs 360 Acid, phosphorous 203 1 Of\ prussic 18y . *KMJ pyrocitnc i^ 386 Indei. Acid, pyrogallic 330 pyroligneous 326 pyrophosphoric 204 racemic 329 rocellic 330 selenic 211 selenious 210 silicic 212 silicohydrofluoric 213 stearic 330 succinic 330 sulphuric 194 sulphurous 192 tannic 32H tnrtaric 327 telluric 268 trllurous 268 titanic 267 tungstic 262 valerianic 330 vanadic Affinity, chemical 105 disposing 147 double 106 effects of 112 elective 106 measure of Ill simple 1 06 Air 160 Alnbaster 290 Albumen 349 Alcohol 341 Alkalies, metallic bases of. . . 218 Alkaline earths 227 Alloys of antimony 265 copper 970 gold 280 lead 272 manganese 24 1 silver 277 sodium and potassium. .. 225 Alum ....*; ) . r .. 294 ammonia 294 Alum stone 294 iron 294 manganese 294 Alkaline springs 360 Alumina 234 Aluminium 234 Aluminous earth 234 Amalgams 275 Amber 340 Ambergris 351 Ammonia 170 Analysis of carbonate of lime 358 Analysis of minerals ........ :r7 mixed gases ........... 356 Angles of crystals .......... 284 plane ................. 284 solid .................. 284 Analysis of mineral waters.. 360 Anhydrite ................. 290 Anthracite ................. 173 Animal acids ............... 350 chemistry . . ........... 349 heat .................. 353 oils and fats ............ 350 Antimonio-sulphurets ....... 319 Antimony ................. V.MJ3 Appendix ........ ^ ........ Aqua fortis ................ 168 potass* ................ -'-> Aerostation ....,...,. ....... 149 Arrow-root ............... Areeniates ................. table of compounds ..... H Arsenic .................. Arsenites .................. 300 Arsenio-sulphurets ......... Arseniureted hydrogen ..... 258 Atomic theory ............. 118 Auro-chlorides ............. 319 B Balloons ................... M! Balaam of sulphur ......... Balsam ................... 340 Barilla .................... Barium ................... Barometer ................. Baryta .................... 227 Barytes .................. 290 Beltroetal . ................ 270 Biborate of soda ............ 308 Bicarbonate of ammonia ..... 310 potassa ................ :'.!<) soda .................. 310 Bicarburet of nitrogen ...... 188 Bichromate of potassa ....... !$U7 Bichloride of cyanogen ...... 189 mercury ............... 'J? 1 platinum ....>. ......... ','- 1 tin .................... JM titanium ............... tungsten .............. 262 Bicyanuret of mercury ...... 275 Bile ................. 354 Index. 387 Bichloride of molybdenum ... 202 180 Biuiodidc of platinum. . .. . . . 282 14 r . .. 250 lead O7<> . .. A28 magnesium ....... 233 . .. 2(>3 225 Clipper . . . .. 270 1 ( )7 } } ...279 phosphorus 205 hydrogen 153 091 ... 274 selenium .... 211 . .. -><;] silicon 213 . . . 1 64 zinc 247 . .. 281 .. 202 c tin . . . ' 250 47 . . . 2 ,. 228 Cast iron. . 245 388 Index. Cassava ... 336 107 Cementing . . . . :w,\ C e ri n . . 341 '><;;* Cerite ... 26G Complex animal substances. . 173 351 Chloral 181 lf>? CO Dill baryta . . . ... 300 9M4 !>*) ...... 9fW bismuth ...267 .'7-4 bromine . 1 l.'i 3i>7 cadmium ......... 248 . 231 181 252 3V7 ... 270 >-;; cyanogen . . . . . 188 283 lead ... 272 Crystallogenic attraction .... 287 232 263 226 188 233 272 nickel .... 254 >." .. 221 V41 211 954 213 977 . 277 9K soda .... . 225 947 224 99/> Tnbe KM tellurium 268 247 360 .... 179 D 08 * * " " ,.. 284 l.-ad ^ ...,. 307 .... 307 > potassa 307 258 Deliquesce 287 322 Chyle 354 197 .... 333 Difluoborate of ammonia . . . . S16 .... 273 Dipyrophosphate of soda 184 oxide of silver '' nation of metals . 217 soda and basic water .... 3ur> 286 17:> 286 ]). carbonate protoxide of cop- 3^1 1 185 Diahloride of copper .... 251 Dicarbonate of mercury 311 . 344 Dicarburet of hydrogen 1-2 Digester, Marcet's U: phosphate of potassa Diphosphate of ammonia lime magnesia Diphosphuret of iron Din i Irate of protoxide of lead mercury Diniodide of copper Dioxide of copper ijisuiphate of alumina pj-.iloxide of copper Disulphuret of iron nickel Dodecahedron '. Dolomite Double bromides carbonates cyanurets iluorides iodides Drying oils Ductility B Ebullition Effloresce Efaidin Elasticity Electricity Electrical machine Electro-chemical decomposi- tion Electrodes Electrography Electrometer, gold leaf. balance Electro-magnetism theory Electro-magnetic multiplier. . Electrophorus Electrotype Emetia - Emulsion Essences Etching Etherine, four-four carburet of hydrogen Ethers Ethiop's mineral * . . Eudiometer Eudiometry Eupione 33* li^dcx. 55 302 304 304 304 245 297 2.7 270 2(iO 2;<1 244 254 2eo 2SO 320 312 321 321 320 215 52 247 355 338 109 72 74 90 88 104 74 77 91 100 93 77 104 334 338 339 158 184 342 275 152 163 184 389 Evaporation 59 Febrifuge salt of Silvius ..... 221 Feathers .................. 356 Fermentation .............. 345 Fibrin... .................. 349 Filtration ................. 362 Fire-clamp ................. 186 Fixed oils ................. 3:57 Flowers of zinc ............ 247 Fluoborate of ammonia ...... 315 Fluoride of barium .......... 228 calcium ............... 2:U lead ................... 271 lithium ................ 226 magnesium ............ 233 potassium ............. 221 sodium ...... .......... 225 strontium .............. 230 zinc .................. 247 Fluorine .................. 145 Fluosilieate of ammonia ..... 315 Food of plants .............. 348 Fowler's arsenical solution . . 306 Freezing mixtures .......... 50 Fulminating gold ........... 279 platinum .............. 282 silver ................. 277 Fuming liquid of Libavius. . . 250 Fusion .................... 109 Fusion, watery ............. 287 Fusibility .................. 215 G Galena Galvanism * theories effects of Gasometers Gas lights Gastric juice i Gaseous mixtures containing carbonic acid hydrogen nitrogen oxygen Gelatin Germ Germination Glass green bottle crown plate 271 78 '82 84 129 184 353 356 357 357 357 356 349 347 347 213 213 213 213 390 ftgfe, Glass, flint ; 213 Glauber's salts Glucina 236 Glucinium 236 Glue 349 Gluten 336 Gold powder . . .- 280 Green vitriol 291 Graphite 245 Gum 336 arabic 387 Senegal 337 tragacanth 337 reams 340 Gypsum 276 H Hair 355 Hartshorn 170 1 h-mrtitr, red 243 brown 243 Hexahedron 284 Homberg's pyrophorus '4 Hog's lard ,.. 350 Hoiwy 335 Howls 355 Mom :r,:> Hordein 347 Horn silver 277 Hydrates 152 Hydriodate of ammonia 315 Hydro-salts 314 H yd roc Morale of ammonia.. 314 Hydrobromate of ammonia.. 315 Hydrofluate of ammonia .... 315 I lydrocyanate of ammonia. . . 31." Hydrogen 146 Hyduret of potassium 222 Hygrometers 62 Idrialine 184 Ignition 70 Induction 75 Indefinite proportions 114 Indelible ink 298 India rubber 341 Ink 328 Insolubility 108 lodates 301 lodate of potassa 301 Iodide of barium 228 calcium . 231 Iodide of cadmium lead 248 magnesium ............ 13 silver ................. v.'77 sodium ............ .". . . 225 phosphorus ............ 20~> sulphur ............... l!>7 potassium ............. strontium. . . . . . ........ 230 zinc ........ . ......... -JI7 Iodine .................... 140 Iron ...................... 241 Iron pyrites ................ 244 Iridium ................... 282 Indochlorides .............. 320 Isomorphism ............... 2n7 Ivory-black ................ 17:; K Kalium ................... 218 Kermes mineral ........... Kelp ..................... 309 Lakes -.... :,u Lamp-black 173 Lapis causticus Latanium 2H3 Lead si?l Leyden jar 76 Light reflection of (>'> refraction of decomposition of <>7 absorption of Light carbureted hydrogen . . I J Liquefaction 49 Lignin Lime "..., Lime-water 'J30 Liquorice :j:5T> Litharge i>71 Lithia i>J6 Lithium Litmus :'.!.'. Lucifer matches 300 Lunar caustic 298 M Madder 345 Magnesium 232 Magistery of bismuth 2<>7 Magnesia i>33 Index. 391 Magnetic iron pyrites 244 Ma trie circle 9G Malleability 214 Magneto-electric induction . . l .)'j Magneto-electric machine . . 99 Manganese 238 Manua 335 Maigarine 351 Massicot 271 Matches 30C Membranes 355 Mi-lair* 214 Metallic lustre 214 Metaphosphates 305 Mercury 273 Mtlk Microcosmic salt 303 Mineral green. 311 Molasses 335 Molybdosulphurets 318 M.'.lybdosulphuret of potassa. 318 Molybdenum 261 M->rph:a 332 Mosaic gold 251 Mucus 354 Muscle 356 Myricine 341 Nails 355 Naphtha 184 Naphthaline 184 Narcotina 333 Natron 223 Natural substances 321 Neutral substances 334 Nickel i 253 Nicotina 334 Nitre 295 Nitric oxide 164 Nitrous oxide 163 Nituret of potassium 222 Nitrates 295 Nitrate of ammonia. . . .* 296 baryta 296 lime 297 magnesia 297 potassa 295 soda 296 strontia 297 protoxide of copper 297 lead 297 mercury 297 oxide silver 297 Nitrites ." 299 j Nitrogen 153 ! Nitrous ether 343 i Notation ]26 I Nomenclature 122 Ntuc voinica 334 O Oblique prisms 285 rhombic prisms 285 rectangular 285 rhomboidal 285 Octohedron 285 Octohedron, regular 286 square 285 rectangular 286 rhombic 286 OEnanthic ether 342 Oils 337 Oily acids 330 Oil gas 183 Oleine 331 Olefiant gas 182 Orpiment 258 Osmium 282 Osmazome 350 Osmio-chlorides 320 Oxalate of potassa 325 of lime 326 Oxalic ether 343 Oxigenation 133 Oxidation 133 Oxide of selenium 210 cadmium 248 carbon 196 phosphorus 202 titanium 267 silver 277 strontium 230 Oxychlorides 320 chromium 260 Oxygen 128 Oxysalts 287 Oxysulphuret of antimony.. 265 Palladium 282 Palladio-chlorides 319 Palm-oil 339 Paracyanuric acid 189 Paranaphthaline 184 Parraffine 184 Peat 173 Pearlash 308 Perbromide of phosphorus . . . 205 Percarbureted hydrogen 183 392 Percussion powder 2 four-three oxcobalt 252 titanium 2l>7 tellurium 268 lead 271 Permuriate of tin 250 iVrsuhihuret of arsenic 258 tellurium 268 Perphosphuret of iron 245 Pewter 265 Phosphureted hydrogen 206 Phosphorus 200 Phosphorescence 70 Phosphates 302 Phosphate of potassa 302 soda and ammonia 303 ammonia 304 lime 304 magnesia and ammonia. . 304 Phosphuret of potassium .... 22 cadmium 249 calcium 232 manganese 241 hydrogen 205 barium 229 Pitch 340 Pinchbeck 270 Photometers .-. .* 71 Photographic drawing 68 Platinum 281 spongy 2-1 Platinochlorides 31 : biniodide of potassium. . . 320 Plumbago 173 Pneumatic cistern 129 Pot-metal 271 Portable gas 185 Potassa 221 hydrate of. 221 Polassa-fusa . . . 221 Potassium 218 Potash and pearlash Primary forms 284 Printer's types 265 Protobromide of iron 244 potassium Protochloride of iron '.M: ; tin 250 carbon manganese Protochloride of arsenic cerium mercury gold .* platinum 281 uranium Protocyanuret of iron P rot iodide of iron .' 1 ' cadmium 248* carbon 1-1 tin platinum Protohyduret of arsenic .... Protoeulphuret of arsenic .... platinum mercury cerium cobalt nickel manganese ',' II tin iron strontium calcium Protosulphocyanuret of iron . Protoxide of strontium ct-rium hydrogen bismuth '. nitrogen potassium 220 gold 279 sodium 224 copper. 270 lithium.........'. . barium 227 lead 271 calcium magnesium '>''<> mercury 273 thorium 237 manganese 2MS iron 242 platinum 281 zinc ii-17 Index. 393 Protoxide of tin 249 cobalt ; . . . 252 nickel 253 vanadium 201 molybdenum 261 uranium 2(i.> Proximate principles 323 Prussian blue 243 Pus 355 Plumula 347 Putrefactive fermentation .... 346 Pyrometers 37 of Wedgwood 46 of Daniell 46 of Brequet 46 Pyrotechny 296 Pyrophosphates 304 of soda 305 Pyroxylic spirit 343 Q Quadrisilicates 313 Quadrochloride of nitrogen .. 169 Quartation 278 Q,uinia 333 R Radicle 347 Realgar 258 Red dyes 344 Red oxide of manganese 239 lead , 272 Red precipitate . . . t 274 Respiration 180 Resins 340 I\espi ration of plants 348 Revolving rectangle 94 Right prisms 284 Right square prisms 284 rectangular 284 rhombic 284 rhomboidal 284 Rhodium 282 Rhodio-chlorides 320 Rhombohedron '. 285 R.)chelle salt 328 llt.'ck candy 335 gait 224 s Saccharine fermentation 345 Safety lamp 1 87 Sago 336 Sal-ammoniac 314 Saliva Salifiable base Saline springs Saltpetre Salts or secondary compounds double triple Sandarac Scheele's green Sealing-wax Seleniuret of aluminium Seleniuret of potassium Selenium Sesquiphosphuret of alumini- um cobalt Sesquibromide of arsenic .... carbonate of ammonia. . . carbonate of soda Sesquichloride of aluminium. antimony arsenic . . cerium chromium uranium Sesquifluoride of chromium. . Sesquioxide of aluminium. . . . antimony bismuth cerium chromium glucinium manganese nickel platinum sodium tin uranium zirconium Sesquisulphuret of aluminium antimony arsenic chromium tin cobalt , Sesquisulphocyanuret of iron. Sulphocyanuret of barium. . . iron. potassium Shells Silver Silver glance . Silex Silicon 353 283 360 296 283 288 288 254 306 340 235 222 235 253 258 310 309 235 264 257 266 260 266 260 234 264 207 266 259 236 239 254 281 224 250 266 237 235 265 258 260 251 253 245 229 245 223 355 276 277 212 212 394 Silicium Silica Silk Solution ' Spirituous and ethereal sub- stances Spirits of turpentine Soaps Sodium Soda Solder -..# Specific gravity of essential and other oils Spermaceti oil Starch Steam . ........... ;/ artillery engine generator 8teeF. Stream tin Strontia Strontium Strychnia Sugar SKT:::::::::::::: Subphnspharet of cobalt. . . . nickel Subsulphate of protoxide of mercury Subsesquiphosphuret of cop- per Sublimation Suet Sulphur flowers of. . . rool-brimstone Sulphates Sulphate of ammonia alumina baryta lime hthia potassa soda ...- iV strontia potassa and alumina .... potassa and magnesia. . . . protoxide of copper cobalt iron manganese mercury... 212 108 341 2S1 224 121 3f>0 335 56 59 58 58 245 Jl:' U9 :<;;:; 334 Ufl 253 254 293 270 190 350 190 190 190 He SB9 291 290 290 2H9 880 294 2<>4 L> _' 291 Sulphate of nickel silver 3 zinc Sulphureted springs Sulphuret of barium 228 boron bismuth cadmium cobalt copper 270 Sulphuret of cyanogen 200 lead .... 272 potassium silicon sodium silver uranium zinc Sulphur-salts : 6. " for reflection of caloric 31 7. Concave mirror* 31 8. Pyrometers 37 9. 10. A pp. for expansion of liquids 38 11. App. for expansion of air 99 12. Air thermometer 42 13. Differential thermometer 43 14. Common and laboratory do 44 15. Blowpipes 4-1 16. Different scale* of thermometers 45 17. Ri-gMer thermometer 45 18. Metallic thermometer 4G 19. Influence of pressure on the boil- lug point 53 90. Pulse glaa 53 21. App. culinary paradox... 64 SB. Marcet's digester 55 iritlarop 55 94. Steam engine illustrated 56 85, 98. Distillation. Cryopborus..50,60 97. Apparatus for refraction of light. 67 98. Priwn 67 99. Gold leaf electrometer 74 30. Electrical machine 75 31. Apparatus for I nd action 76 39. Electrophone 77 33. Balance electrometer 77 34. Simple voltaic circles 79 35. Calorimotor 80 36. Voltaic pile 61 37. Deflaf rator . . . 81 38. App. for decomposition of water 86 39. Transfer of chemical substances 87 40. App. for change of colors 87 41. Galvanometer 99 42. Revolving rectangle 93 43. Helix and rtand 95 44. Magnet with three poles 95 45. Electro magmt 95 46. Magic circle 96 47. Vibrating magic circle 96 48. 49. Separable helices 97, 98 50. Magneto-electric machine 99 51. Theory of electro-magnetism ... 101 52. Electrotype 104 53. Dropping tube 119 54. App. for change of form 113 55. Ills, of atomic theory 118 56. Specific gravity 121 57. Aerometer 122 58. Pneumatic cistern 129 76. 77. 79. 59. Retorts 130 GO. Lead tubes for connection 131 61, 62,63. Apparatus for oxygen.. J3_> 64. Apparatus for collection of gasea heavier than the air l:W 65. App. for dacoMDOsJUonot w;ii tr ! '>' 66. Gas bag and bubble pipe 67. Method of filling gas bags. . . 68. Balloons, 1 :. 69. Apfi. for musica i . . 1 1'j 7". If \droi;eii pistol 149 71. Eudiiimrii r .pmill.l bli.WpilM) I.Xi 73. \Voulfe*s Hjipnratus 74. App. for obtaining nitrogen. . 75. " for analyzing tli< for obtaining niti showing the properties of nitric an.l I-.H for collecting faMs light. T than the air 17<> for carbonic acid IT* 80. Effect of gauze wire upon flame 187 81. Safety lamp 82. Platinum wire for wicks 1 - v 83. Crytalhr.ation of sulphur. . 84. Crucibles l'J2 85. Production of sulphur in volca- noes r.iy 86. App. for combustion of pin .- , rus in oxygen 87. App. forphcMphureted hydr. 88. Evaporating dihes 908 89. Hexahedron 984 90. Right square prism 984 91. Right rectangular prism 99. Right rh..ml...i.l:il pn-m.... 99. Regular hexagonal prism 94. Rhomhohedron 985 95. Oblique rhombic prism 96. " rhomboidal prism 285 97. Regular octohedron 285 98. Square " 285 99. Rectangular " 286 100. Rhombic 286 101. Dodecahedron 286 102. App. analysis of gases 356 103. App. analysis of minerals 3.V 104. App. to dt-tert hydrwulphuric acid 105. Test tubes 361 106. Mode of folding filters 3>o 1U7 Filters 365 108. App. fur filtration 363 109. Supports 363 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. JAN U 2, t934 LI> 21 UNIVERSITY OF CALIFORNIA LIBRARY