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 32X 
 
 1 2 3 
 
 4 5 6 
 
BY THE SAME AUTHOR. 
 
 CHEMICAL AND GEOLOGICAL ESSAYS. - 
 with a New Preface ; pp. xlvi. and 4S9 ; 8vo. 
 
 •Second Revised Edition, 
 
 MINERAL PHYSIOLOGY AND PHYSIOGRAPHY; With a Gen- 
 eral Introduction, — pp. xvii. and 710. 
 
 Contents. — Preface; I., Nature in Thought and Language; II., 
 The Order of the Natural Sciences; III., Chemical and Geological Relations 
 of the Atmosphere; IV., Celestial Chemistry from the Time of Newton; 
 v., The Origin of Crystalline Rocks; VI., The Genetic History of Crystal- 
 line Rocks;; VII., The Decay of Crystalline Rocks; VIII., A Natural 
 System in Mineralogy, with a Classification of Silicates; IX., History of 
 Pre-Canibrlan Rocks ; X., The Geological History of Serpentine, with Studies 
 of Pre-Cambrian Rocks ; XI., The Taconic Question in Geology ; Appendix; 
 and Index. 
 
 IN PREPARATION: 
 
 MINERALOGY ACCORDING TO A NATURAL SYSTEM. -The 
 
 bignificance of the pliysical characters on which the Natural-History 
 system of Mineralogy has been based, and their relations to the chemical 
 characters of the system of Berzelius and his followers, are set forth in 
 the author's volume entitled A New Basis for Chemistry, and more 
 fully in his Mineral Physiology and Physiography, pages 279-401, 
 687, 688, where a tabular view of the Classes and Orders of the Natural 
 System is given, on page 382. 
 
 The principal points in the new treatise will be : (i) Arrangement of all 
 native and artificial species of the mineral kingdom in classes and orders 
 upon a chemical basis; (2) Their complex chemical structure and high equiva- 
 lent weiglits; (3) Application to them of the principles of polymerism and of 
 homologous or progressive series; (4) Direct relations of the constitution of 
 solids, not only to their specific gravity, but to their hardness and their 
 greater or less chemical indifference, which latter are shown to be connected 
 with the variations in condensation or so-called atomic volume; (5) Recogni- 
 tion of the wide distinction between crystalloid and colloid or amorphous 
 species; (6) Sub-division, on the above grounds, of the orders and sub-orders 
 into tribes, which generally correspond with the orders of the Natural-History 
 system; (7) Arran;j:L'inent of tribes in genera and species, and designation of 
 these by a binomial Latin nomenclature ; (8) Systematic descriptions of 
 native and of some related artificial species; (9) Genetic history of native 
 species, and their artificial production; (10) Their relations to the great 
 groups of rocks in the earth's crust 
 
A NEW 
 
 BASIS FOR CHEMISTRY: 
 
 A CHEMICAL PHILOSOPHY. 
 
 BY 
 
 THOMAS STERRY HUNT, M.A., LL.D. (Cantab.), 
 
 AUTHOB OF "chemical AND OKOLOGICAL ESSAYS," "MINERAL 
 
 PHYSIOLOGY AND PHYSIOGRAPHY," 
 
 ETC., ETC. 
 
 Omnia mensura ot niimcro ct pondnre disposuistl. 
 — Lib. Sapientiae,cap. zX. 
 
 BOSTON: 
 
 SAMUEL E. CASSINO. 
 
 1887. 
 
Copyright, 1886, 
 By Samuel E. Cassino. 
 
 \6 
 
 Hq43 
 
 "^VofNewB.?^ 
 
 39009 
 2/« 
 
 Elrctrotvpbd 
 By C. J. Phters and Son, Boston. 
 
€a 
 
 J. B. STALLO, 
 
 CITIZEN- JURIST-PHILOSOPHER, 
 
 THIS VOLUME IS GRATEFULLY 
 
 DEDICATED BY THE 
 
 AUTHOR. 
 
-r^< 
 
PREFACE. 
 
 It is now more than thirty-eight years since 
 the author, repelled by the contradictions which 
 result from the introduction into chemistry of 
 the atomic hypothesis, and seeking a better 
 foundation than that on which Dalton endeav- 
 ored to build a theory of the science, began a 
 series of publications, having for their object, 
 in the words employed in 1853, to define the 
 " principles which may serve as the basis of a 
 sound theory of chemistry," and at the same 
 time "to enlarge and simplify the plan of chem- 
 ical science." In pursuance of this plan to the 
 present time, he has persistently followed the 
 line of argument foreshadowed in 1848, and 
 fully stated in 1853. Advances were made in 
 the succeeding years ; but the crucial problem, 
 the solution of which was required to complete 
 the projected philosophy of chemistry, namely, 
 that of the relation of equivalent weight to 
 
T •' Preface. 
 
 specific gravity in liquids and solids, remained 
 unresolved until the summer of 1886. With its 
 solution, the author believes that the object so 
 long ago proposed has been attained, and that 
 we have the elements of a new and simple 
 Chemical Philosophy, which he ventures to des- 
 ignate A New Basis for Chemistry. 
 
 Rejecting all hypotheses regarding the con- 
 stitution of matter, as irrelevant to the study of 
 chemistry when rightly understood, and as per- 
 taining to the wholly distinct realm of dynam- 
 ics, the author has attempted to define the 
 limit between the two, and to show that the 
 phenomena of solution, fusion, volatilization, 
 liquefaction, solidification, and crystalHzation, — 
 in a word, all changes of state, — belong to the 
 domain of chemistry, and that, from a right 
 consideration of these, some of the most ob- 
 scure problems of the science become clear. 
 He has therefore endeavored, in a series of 
 chapters, and, in large part, in language quoted 
 from his earlier writings, to define the princi- 
 ples upon which he believes may one day be 
 built a New Chemistry. 
 
 The reader will note that the plan and the 
 
Preface. 
 
 vii 
 
 limits of this little volume exrUide the discus- 
 sion of many subjects which would find a place 
 in a systematic treatise on chemical theory. 
 Among these are the consideration of the 
 periodic law in relation to the law of numbers, 
 the question of valency, and the problems of 
 thermo-chemistry, all of which must be reserved 
 for another time and place. 
 
 It would be unjust on the part of the author 
 not to express his many obligations to J. B. 
 Stallo, now the American Minister at the Court 
 of Italy, whose suggestive volume on the Phi- 
 losophy of Nature, in 1848, was, at that early 
 date, a source of inspiration ; whose friendship 
 during many years has encouraged the writer 
 in his labors ; and whose later volume, on The 
 Concepts and Theories of Modern Physics, in 
 1882, has served to confirm him in the position 
 which he has long maintained with regard to 
 the philosophy of the sciences. To Stallo, 
 therefore, this book is dedicated. 
 
 Boston, January i, 1SS7. 
 
^ Jfi.) ipiw 
 
 h 
 
CONTENTS. 
 
 CHAPTER I. 
 
 INTRODUCTION. 
 
 A new theory of chemistry proposed 
 
 List of the author's publications thereon from 1848 to 1886 
 
 Their partial republication in 1S74 ^nd 18S6 
 
 Their analysis and the completion of the theory attempted 
 
 I 
 I 
 
 5 
 6 
 
 CHAPTER II. 
 
 NATURE OF THE CHEMICAL PROCESS. 
 
 Chemistry as distinguished from physics 
 
 Origin of chemical species by metagenesis and metamorphosis . 8 
 
 Metamorphosis by expansion and by condensation, or polymerism, 8 
 
 Chemical genealogy ; double decomposition 
 
 Polymerism in sulphur-vapor ; in carbon and phosphorus ... 10 
 
 Nature of double decomposition ; catalysis ,, 
 
 Genealogy of species ; their homogcneousness j. 
 
 Chemical identification and differentiation jg 
 
 Chemical integration and disintegration j- 
 
 Crystalline individuality ; chemism, dynamics, biotics . . . .* 18 
 
 Mineralogy and biology ; physiology of matter ,3 
 
 Classification of natural sciences tabulated jg 
 
 Chemism often confounded with dynamism 20 
 
 The activities of matter on different planes 21 
 
 Solution defined as chemical union ^2 
 
 ix 
 
Contents. 
 
 CHAPTER III. 
 
 GENESIS OF THE CHEMICAL ELEMENTS. 
 
 Oken ; his Physiophilosophy and scheme of the sciences ... 23 
 
 Genesis of elements from a primal matter 23 
 
 Cosmogony ; stoichiogeny, or the genesis of elements .... 24 
 
 Studies of Dobereiner, Pettenkofer, and Dumas 24 
 
 Prout's hypothesis of equivalent weights 25 
 
 Brodie's Calculus and his ideal elements 26 
 
 Celestial chemistry ; universality of dissociation 28 
 
 Brodie's Ideal Chemistry in relation to dissociation 29 
 
 Clarke on stellar chemistry ; Lockyer's extension of the view . . 31 
 
 Supposed elemental matter in the solar chromosphere .... 32 
 
 Chemistry of nebula; ; an interstellar medium 33 
 
 Genesis by condensation from primal matter restated .... 35 
 
 The view reiterated by Mills and by Crookes 36 
 
 CHAPTER IV. 
 
 GASES, LIQUIDS, AND SOLIDS. 
 
 Relations between the densities of gaseous and solid species . . 38 
 
 Polymerism and high equivalents of solids 39 
 
 The condensation in liouid species 40 
 
 Liquids and solids as polymers of vapors 41 
 
 Possibility of fixing their equivalent weights 42 
 
 CHAPTER V. 
 
 THE LAW OF NUMBERS. 
 
 Homologous or progressive series in chemistry 43 
 
 Organic chemistry the chemistry of carbon 44 
 
 Extension of the ■ inception of progressive series 44 
 
 Isomeric and anisomeric homologues 45 
 
 Signilicanc: of types and structural formulas 45 
 
 The bearings of the periodic law 46 
 
Coittaits, jjj 
 
 CHAPTER VI. 
 
 EQUIVALENT WEIGHTS. 
 
 The conception of pol3-c.-irbonates and polysilicates 
 Their elevated equivalent weights 
 
 High equivalents in ammonio-cobalt salts and p'olytungs'tates ." ' 48 
 Complex inorganic acids of Gibbs 
 
 Summary of the author's views in i8?i ^^ 
 
 ^^ 49 
 
 CHAPTER VH. 
 
 HARDNESS AND CHEMICAL INDIFFERENCE. 
 
 Density, hardness, and chemical indiflference related .... r, 
 
 their connection with condensation 
 
 the doctrine as stated in 1863 
 
 Relations between chemical ai.d physical characters . . .'. \ !! 
 Types of mineral silicates ; porodic bodies 
 
 Hardness and indifference in oxyds and metallic species" .' .' ." !! 
 
 Action of fluorhydric acid on silicates \ 
 
 Studies of J, B. Mackintosh thereon ....*.'**'' ^ 
 
 CHAPTER Vni. 
 
 THE ATOMIC HYPOTHESIS. 
 
 Two hypotheses as to the constitution of matter gg 
 
 The .-itomic hypothesis down to Dalton's time ....... 60 
 
 The kinetic theory of gases 
 
 Whewell on the difficulties of the atomic hypothesis . . . . . 6,' 
 
 Its relations to chemical theory 
 
 The question of so-c-illed molecular volumes ...... 61 
 
 They .ire the reciprocals of the coefficient of condensation .' .' ." 64 
 
 Misconceptions as to the chemical jirocess ^. 
 
 Extension of the atomic hypothesis from dynamics' to chemistry .' 66 
 
 Its mapphcability to chemical phenomena gg 
 
Xll 
 
 Contents. 
 
 CHAPTER IX. 
 
 THE LAW OF VOLUMES. 
 
 The doctrine of chemical equivalents based on volume .... 68 
 
 The great generalization of Gay Lussac 69 
 
 All things are by measure, and number, and weight 69 
 
 Universality of the law of volumes 70 
 
 Condensation from the gaseous to the solid state 70 
 
 Supposed relations of volume to isomorphism 71 
 
 Conclusions thereon of Dumas and others 72 
 
 The significance therein of crystalline form questioned .... 73 
 
 The coefficient of condensation determined 75 
 
 Relations of density between steam and water 76 
 
 Relations between hydrogen, steam, and water 77 
 
 Equivalent weights of water and of ice 78 
 
 An expression sought for the volume 79 
 
 CHAPTER X. 
 
 METAMORPHOSIS IN CHEMISTRY. 
 
 Chemism defined ; metagenesis and met.imorphosis 80 
 
 Metamorphosis as polymerization and depolymerization ... 81 
 
 Fusion, vaporization, and condensation are chemical changes , . Si 
 
 Arbitrary chemical units for non-volatile species 82 
 
 Metaniorphoses of aldehyde 83 
 
 Chloral and methylene oxyd 84 
 
 The various turpentine-oils 85 
 
 Pontine and its polymerization 86 
 
 The lieat evolved in such changes 87 
 
 Exemplified by metallic oxyds and silicates 88 
 
 Metamorphosis of sulphur-vapor 89 
 
 Polymerism of vapors under pressure 90 
 
 Various liquid polymers; forms of phosphorus 91 
 
 Metamorphosis of tin 92 
 
 Oxygen and ozone ; iodine and chlorine 93 
 
 III 
 
Contents. xiii 
 
 Dissociation a universal law , 
 
 . 94 
 
 Stages in chemical metamorphosis 
 
 Determination of the unit in polymerization ^ 
 
 Uhistrations of condensation 
 
 Species soluble and insoluble in water ' o 
 
 98 
 
 CHAPTER XI. 
 
 THE LAW OF DENSITIES. 
 
 The densities of calcium carbonate examined ,0 
 
 The revised combining weigiit of oxygen .... 
 Variations in density of related species 
 Breithaupt's studies of the calcites 
 Their calculated formulas and densities 
 
 The principle of crystalline admixture "106 
 
 Relations in density of gases and solids ' xoi 
 
 The reciprocal of the coefficient of condensation ...... ,oS 
 
 Densities of water, steam, and hydrogen compared . .' " .' * ,09 
 The density of the hydrocarbon butane 
 
 The formula p~ d = v considered . 
 
 no 
 
 CHAPTER Xn. 
 
 A HISTORICAL RETROSPECT. 
 
 The doctrine of high equivalents and complex formulas ... 1,2 
 Conclusions of Favre and Silbermann 
 
 Graham on polymerism of dissolved salts 
 
 Spencer Pickering on molecular weights 
 
 Guthrie on molecular equivalents 
 
 Tilden and Shenstone on sohition at high temperatures' '. '. [ nl 
 
 Louis Henry on the polymerization of oxyds " ,,s 
 
 Density as a function of equivalent weiglit ... 
 
 Henry's inquiry for the coefficient of polymerization.' . '. ' ' ]Z 
 He restates the author's argument of 18; 1 
 
XIV 
 
 Cojiteiits. 
 
 Oxyds classified with regard to polymerization ...... 121 
 
 Henry Wurtz's geometrical chemistry 122 
 
 His hypothesis of varying molecular diameters ...... 124 
 
 His mode of calculating densities examined 125 
 
 Graham on gaseous and liquid diffusion 128 
 
 His scale of solution-densities 130 
 
 His complex or polymeric molecules 130 
 
 Non-diffusible bodies, or colloids 132 
 
 Favre and Silberniann on some chemical . iianges 133 
 
 Henri Sainte-Claire Deville on dissociation 133 
 
 Dissociation compared to evaporation 134 
 
 Diffusion in gaseous dissociation 135 
 
 Combination compared to condensing of vapors 136 
 
 Connections and consequences of the work of Graham and Deville, 137 
 
 CHAPTER XIII. 
 
 CONCLUSIONS. 
 
 The chemical process again defined 139 
 
 Heterogeneous and homogeneous changes 140 
 
 Metamorphosis and polymerization 141 
 
 Varying stability of polymers 142 
 
 Metamorphoses of so-called elements 143 
 
 Genesis of elemental species 143 
 
 Changes of state considered 144 
 
 Condensation as related to hardness and insolubility 145 
 
 The law of volumes considered 146 
 
 Relations of water, steam, and hydrogen gas 147 
 
 The proportion d.pwwv re-examined 148 
 
 The coefficient of coadcnsation 149 
 
 Density of solids and liquids a function of equivalent weight . 149 
 
 The atomic hypothesis in its relations to chemistry 150 
 
 Pressure as related to chemical change 151 
 
 Heat as the universal disintegrator 151 
 
 Relations of chemistry to dynamics and biotics 152 
 
 
A BASIS FOR CHEMISTRY. 
 
 CHAPTER I. 
 
 INTRODUCTION. 
 
 § I. At an early period in his chemical stud- 
 ies, the writer was led to adopt certain principles 
 which, as said in 1853, would, it was thought, 
 "be found to enlarge and simplify the plan of 
 chemical science," and might "serve as the 
 basis of a sound theory of chemistry," which he 
 believed to be wanting. His principal publica- 
 tions on this subject, from 1848 to 1886, seven- 
 teen in number, are as follows : — 
 
 1. On some Anomalies in the Atomic 
 Volumes of Sulphur and Nitrogen, with 
 Remarks on Chemical Classification ; 
 American Journal of Science for September, 
 1848 (vi. 170-178). 
 
 2. On some Principles to be Considered 
 IN Chemical Classification ; read at the first . 
 
 i 
 
m 
 
 2 A Chemical Philosophy. 
 
 meeting of the American Association for the 
 Advancement of Science, Philadelphia, Septem- 
 ber, 1848, and published in the American Jour- 
 nal of Science in 1849 (vol- vii. 399-405 ; 
 viii. 89-95). 
 
 3. A short treatise on Organic Chemistry, 
 forming Part IV, (pp. 377-538) of the First 
 Principles of Chemistry by B. Silliman, Jr., 
 third edition, 1852. The novel points in 
 chemical theory in this treatise are resumed by 
 the writer in the American Journal of Science 
 for 1853 (vol. XV. 150-152), and set forth more 
 at length in the next paper mentioned. 
 
 4. On the Theory of Chemical Changes 
 AND ON Equivalent Volumes ; published in 
 March, 1853, in the American Journal of 
 Science (xv. 226-234), reprinted in the same 
 year in the London, Edinburgh, and Dublin 
 Philosophical Magazine, and in a German trans- 
 lation in the Chemisches Centralblatt (1853, 
 page 849). 
 
 5. On the Constitution and Equivalent 
 Volume of some Mineral Species ; in the 
 American Journal of Science for September, 
 1853 (xvi. 203-218). 
 
Introduction. 
 
 n 
 
 6. Illustrations of Chemical Homol- 
 ogy ; read before the American Association 
 for the Advancement of Science, at Washing- 
 ton, May, 1854; published in its Transactions 
 for that year (pages 237-247), and in part in 
 the last named journal for September, 1854 
 (xviii. 269-271). 
 
 7. Thoughts on Solution and the Chemi- 
 cal Process ; in the American Journal of 
 Science for January, 1855 (xix. 100-103), and 
 in the Chemical Gazette for the same year, 
 page 90. 
 
 8. The Theory of Types in Chemistry; 
 in the American Journal of Science for March, 
 1 86 1 (xxxi. 256-264). 
 
 9. SuR la nature du Jade ; in the Compte 
 Rendu of the French Academy of Sciences of 
 June 29, 1863, and in an English translation by 
 the author in the American Journal of Science 
 for the same year (xxxvi, 426-428). 
 
 10. The Object and Method of Miner- 
 alogy ; read before the American Academy of 
 Sciences in Boston, January, 1867, and pub- 
 lished in the American Journal of Science for 
 May of that year (xliii. 203-206). 
 
I. 
 
 1! I 
 
 4 A CJiemical PJiilosopliy. 
 
 11. The Chemistry of the Primeval 
 Earth ; a lecture before the Royal Institution 
 of Great Britain, London, May 31, 1867, pub- 
 lished in the Proceedings of the Institution, 
 and the Chemical News of June 21, 1867, sev- 
 eral times reprinted, and translated into French 
 in Les Mondes. 
 
 12. A Century's Progress in Theoretical 
 Chemistry ; being an address delivered at the 
 grave of Priestley, in Northumberland, Pennsyl- 
 vania, on the Centennial of Chemistry, July 3 i, 
 1874, and published in the American Chemist 
 for August and September of that year. 
 
 13. The Chemical and Geological Rela- 
 tions OF the Atmosphere ; published in the 
 American Journal of Science for May, 1880 
 (xix. 349-363). 
 
 14. The Domain of Physiology; or Na- 
 ture IN Thought and Language ; read be- 
 fore the National Academy of Sciences, Wash- 
 ington, April 18, 1 88 1, and published in the 
 London, Edinburgh, and Dublin Philosophical 
 Magazine for October of that year (V, xii. 
 223-253). 
 
 15. Celestial Chemistry from the Time 
 
Introduction. 
 
 5 
 
 OF Newton; read before the Philosophical 
 Society of Cambridge, England, Nov. 28, 1881, 
 and published in its Proceedings (vol. IV. part 
 iii) ; in the Chemical News, and in the Ameri- 
 can Journal of Science for February, 1882 
 (xxiii. 123-133). 
 
 16. A Natural System in Mineralogy, 
 WITH A Classification of Silicates ; read 
 before the National Academy of Sciences, at 
 Washington, in April, 1885, and before the 
 Royal Society of Canada, at Ottawa, in May, 
 
 1885, and published in the Transactions of 
 the latter Society for the same year (vol. III. 
 part iii. pp. 25-93). 
 
 17. The Law of Volumes in Chemistry; 
 published in Science for September 10, 1886. 
 
 Of the above papers, 4, 7, 8, 10, and 11, with 
 portions of 5, 6, and 9, were reprinted in the 
 author's Chemical and Geological Essays (first 
 and second editions), in 1874 and 1878; while 
 13, 14, 15, and 16 appear, with some additions, 
 in his Mineral Physiology and Physiography, in 
 
 1886. A general view of all these was em- 
 bodied in two papers, entitled : A Basis for 
 Chemistry; and Hardness and Chemical 
 
i 
 
 i I 
 
 6 A Chemical Philosophy. 
 
 Indifference in Solids; — read before the 
 National Academy of Sciences, in Boston, 
 November 9 and 1 1, and noticed in Science 
 for November 19, 1886. 
 
 § 2. The fundamental points in the author's 
 system were already set forth in the earlier 
 papers, prior to 1855 ; since which time great ad- 
 vances have been made in dynamical and chem- 
 ical knowledge. The results of all these lead 
 the writer to conclude that the principles laid 
 down by him a generation since should be again 
 brought forward, and presented in a concise 
 form to the attention of the scientific public, 
 with such additions as are required to complete 
 the philosophy of chemistry then first enun- 
 ciated. 
 
 The propositions which were advanced in the 
 various publications named are here set forth, 
 in large part in language quoted from these, 
 in a series of chapters. In making such quota- 
 tions, reference is made by appended numbers 
 corresponding to those prefixed in the preced- 
 ing list. 
 
CHAPTER II. 
 
 NATURE OF THE CHEMICAL PROCESS. 
 
 § 3- In inquiring into the philosophy of 
 chemistry, it was said in 1853 : "We commence 
 by distinguishing between those phenc .ncna 
 which belong to the domain of physics and 
 those which belong to the chemical history of 
 matter. Under the first head we have, be- 
 sides the gravity of matter in the abstract, its 
 various conditions of consistence, shape, and 
 volume, with the relation of the latter to 
 weight, constituting specific gravity, and the 
 relations of heat, light, electricity, and mag- 
 netism." These not only "modify physically 
 the specific characters of matter, but they have 
 besides important relations to those higher 
 processes which give rise to new species" by 
 a complete change in the specific phenomena 
 of bodies. In the capacity of such changes 
 consists the chemical activity of matter." Pro- 
 ceeding, then, to discuss the question of the 
 
8 
 
 A Oiemical Philosophy. 
 
 origin of new species, and the relations of indi- 
 viduals, it was said : " That mode of generation 
 which produces individuals like the parent can 
 present no analogy to the phenomena under 
 consideration ; metagenesis or alternate genera- 
 tion, and metamorphosis, are, however, to a cer- 
 tain extent, prefigured in the chemical changes 
 of bodies." These terms were then adopted in 
 chemical language ; and it was said that meta- 
 genesis, or the production of new species 
 where two or more are concerned, " is effected 
 in two ways : by condensation and union on 
 the one hand, and by expansion and division on 
 the other. In the first case, two or more spe- 
 cies unite and merge their specific character in 
 those of a new species ; in the second case, the 
 process is reversed, and a body breaks up into 
 two or more new species." Of chemical meta- 
 morphosis, which embraces the phenomena of 
 polymerism, it was said : " In metamorphosis 
 by condensation only one species is concerned ; 
 and in metamorphosis by expansion the result 
 is homogeneous and without specific difference." 
 § 4. " The chemical history of bodies is a 
 record of these changes ; it is, in fact, their 
 
Nature of the Chemical Process. 
 
 genealogy. ... By union we rise to indefi- 
 nitely higher species ; but in division a limit is 
 reached in the production of species which 
 seem incapable of farther division ; and these, 
 being regarded as primary or original species, 
 are called chemical elements." The processes 
 of union and division " continually alternate 
 with each other ; and a species produced by the 
 first may yield by division species unlike its 
 parents. From this succession results double 
 decomposition, or equivalent substitution, which 
 always involves a union followed by division; 
 although, under the ordinary conditions, the 
 process cannot be arrested at the intermediate 
 stage. In the production of hydrochloric gas 
 from chlorine and hydrogen, union takes place, 
 followed by immediate expansion without spe- 
 cific difference (metamorphosis) " ; while in the 
 case of compounds of chlorine with hydrocar- 
 bons, which, under changed conditions, break 
 up into hydrochloric acid and a chlorinized 
 species, it was said, " we observe the intermedi- 
 ate stage." 
 
 "A body may divide into two or more new 
 species ; yet it is evident that these did not pre- 
 
 ^ 
 
 i ! S L 
 
 ■*',■:'■ 
 
 ■r \ 
 
wja 
 
 10 
 
 A Chemical Philosophy. 
 
 it! 
 
 ili'l! 
 
 ;ii 
 
 exist in it, from the fact that a different divis- 
 ion may yield other species whose pre-exist- 
 ence is incompatible with the last ; nor can 
 the pre-existence of any species but those which 
 we have called primary be admitted as possible. 
 . . . For these reasons it is conceived that the 
 notion of pre-existing elements, or groups of 
 elements, should find no place in the theory 
 of chemistry. Of the relation which subsists 
 between the higher species and those derived 
 from them, we can only assert the possibility, 
 and, under proper conditions, the certainty of 
 producing the one from the other. Ultimate 
 chemical analyses and the formulas deduced 
 from them serve to show what changes are 
 possible in any body, or to what new species it 
 may give rise by its changes." (4.) 
 
 § 5. The question of metamorphosis by con- 
 densation, or polymerism, noticed above, had 
 already been discussed at some length in 1848, 
 in considering the vapor-density of sulphur, 
 when it was shown that, if regarded as " con- 
 sisting of three equivalents combined in one, 
 the density of its vapor is no longer an anom- 
 aly, as the sulphur-vapor is condensed to one- 
 
Nature of the Chemical Process. 
 
 ir 
 
 third its normal bulk, and its equivalent num- 
 ber is i6 X 3 =48" [32 X 3= 96, in the present 
 notation]. It was at the same time proposed 
 to consider ozone as a similar triple group 
 (000) corresponding to sulphur-vapor (SSS) 
 and to (SOO). (1.) Post, § 56. 
 
 In the same year these conclusions were 
 referred to in connection with polymerism in 
 hydrocarbonaceous bodies, and allotropism in 
 elements was explained as polymerism con- 
 nected with a change in chemical relations. 
 It was said : " Those substances which are con- 
 sidered as elementary may change their equiva- 
 lents, at the same time undergoing a change in 
 their densities; and, as we obtain from the 
 ordinary equivalent and density an idea of ' the 
 volume of the atom,' we say of those forms 
 having an increased density and a correspond- 
 ing increase of equivalenL (so tliat the atomic 
 volume remains unchanged) that two or more 
 molecules have united in one. This is illus- 
 trated in the case of sulphur," and, as was 
 farther shown, in the compounds of mercury, 
 copper, and iron. 
 
 "The so-called elements may then possess 
 
 u 
 
12 
 
 A Chemical Philosophy. 
 
 ,11' 
 
 different atomic weights, which enjoy a simple 
 relation to each other, and in these different 
 states exhibit very different characters. When 
 we speak of one of these as containing two or 
 three atoms of another form condensed into 
 one, it is only an expression in accordance with 
 previously existing ideas. We can no longer 
 attach to the atomic weights of the supposed 
 elements an absolute value [that is, as being 
 the weight of an absolutely elemental species] ; 
 and thus one of the characteristics which serve 
 to distinguish them from known compounds is 
 rendered of no importance." In farther illus- 
 tration of this conception, it was then and 
 there suggested that charcoal, graphite, and 
 diamond being " polymeric modifications of 
 elemental carbon," the first of these " is a spe- 
 cies of anhydrid derived from cellulose " ; and, 
 moreover, that the allotropic red phosphorus 
 might be a similar polymer; — a question which, 
 it was said, "would be solved by a determina- 
 tion of its density in that state." (2.) 
 
 § 6. In 1854, returning to the subject of 
 chemical change, and discussing the question 
 of double decomposition, it was illustrated by 
 
Nature of the CJicmical Process. 
 
 13 
 
 the production of arsenious oxycl and chlorhydric 
 acid by the action of water on terchlorid of 
 arsenic, when it was said : " This decomposi- 
 tion of the sokition of chlorid of arsenic is an 
 example of Avhat is generally called double elec- 
 tive affinity {attractio electiva duplex), and is 
 generally explained by saying that the attrac- 
 tion of arsenic for oxygen, and that of chlorine 
 for hydrogen, enable the chlorid and the water 
 to decompose each other. But these elemental 
 species tlo not exist in the solution, although 
 they are possible results of its decomposition ; 
 and to explain the process in this manner is 
 to ascribe it to the affinities of yet unformed 
 species." 
 
 It was farther said that " double decomposi- 
 tion always involves union followed by division ; 
 although we cannot in every case arrest the 
 process at its first stage. Under some changed 
 conditions of temperature and pressure the de- 
 composition may be counterpart of the previous 
 union " ; as in the example then given of mer- 
 cury and o.xygen. " When the division takes 
 place in a sense different from the union, giving 
 rise to new species, we have double decomposi- 
 
 
^m 
 
 14 
 
 A Chemical Philosophy. 
 
 m\\\ 
 
 iii; 
 
 tion, ... It is only when looked upon as a 
 momentary combination, followed by a decom- 
 position, that the theory of double decomposi- 
 tion becomes intelligible and is in accordance 
 with known facts. From the narrow limits of 
 temperature which often include the processes, 
 and from the ease with which light, warmth, 
 friction, and pressure excite the decomposition 
 of such bodies as the chlorid of nitrogen, the 
 nitrite of ammonia, the oxyds of chlorine, and 
 the metallic fulminates, we may conclude that 
 within still narrower limits, and under condi- 
 tions as yet undefined, many bodies may exhibit 
 affinities for each other which are reversed by 
 a very slight change of condition. In this way 
 we may explain many of those obscure phenom- 
 ena hitherto ascribed to action by presence or 
 catalysis." {7.) 
 
 § 7. The above doctrines were restated in 
 1861, as follows: "All chemical changes are 
 reducible to union (identification) and division 
 (differentiation). When in these changes only 
 one species is concerned, we designate the 
 process as metamorphosis, which is either by 
 condensation or by expansion (homogeneous dif- 
 
Nature of the Chemical Process. 
 
 IS 
 
 ferentiation). In metagenesis, on the contrary, 
 unlike species may unite and, by a subsequent 
 heterogeneous differentiation, give rise to new 
 species, constituting what is called double de- 
 composition ; the results of which, differently 
 interpreted, have given rise to the hypothesis 
 of radicles, and the notion of substitution by 
 residues, to express the relations between the 
 parent bodies and their progeny. The chemi- 
 cal history of bodies is a record of these 
 changes ; it is, in fact, their genealogy, and 
 in making use of typical formulas to indicate 
 the derivation of chemical species, we should 
 endeavor to show the ordinary modes of gen- 
 eration." (8.) 
 
 § 8. In farther exposition of the nature of 
 the chemical process, it was said in 1853 : 
 " Chemical species are homogeneous ; tota in 
 minimis cxistit naturay " Chemical combina- 
 tion is not a putting together of molecules, but 
 an interpenetration of masses." " Chemical 
 union is interpenetration, as taught by Kant, and 
 not juxtaposition, as conceived by the atomistic 
 chemists. When bodies unite, their bulks, like 
 their specific characters, are lost in those of 
 
 «S{ 
 
 -^\\ 
 
 ' ( 
 
. i 
 
 M 
 
 i6 
 
 A Clicviical Philosophy, 
 
 the new species." (4.) In the year 1855 it 
 was farther said of Kant's definition, that "the 
 conception is mechanical, and therefore fails 
 to give an adequate idea. The definition of 
 Hegel, that the chemical process is an identifica- 
 tion of the different and a differentiation of 
 the identical, is, however, completely adequate. 
 Chemical union involves an identification not 
 only of the volumes (interpenetration mechani- 
 cally considered), but of the specific character 
 of the combining bodies, which are lost in 
 those of the new species," (7.) In farther 
 illustration of the above conception, in 1867, 
 in referring to the speculations of Macvicar and 
 Gaudin, as to " the arcj;iitecture of crystalline 
 molecules," it was written : " Nature builds up 
 her units by interpenetration and identification, 
 and not by juxtaposition of the chemical ele- 
 ments." (10.) 
 
 §9, In 1874, in again discussing this ques- 
 tion, it was said : *' In chemical change the 
 uniting bodies come to occupy the same space 
 at the same time, and the impenetrability of 
 matter is seen to be no longer a fact. The 
 volume of the combining substances is con- 
 
Nature of the Chemical Process. 
 
 17 
 
 founded, and all the physical and physiological 
 characters which are our guides in the region 
 of physics fail us, gravity alone excepted. 
 The diamond dissolves in oxygen, and the 
 identities of chlorine and sodium are lost 
 i^ that of sea-salt. To say that chemical 
 union is, in its essence, identification, as 
 Hegel has defined it, seems to me the sim- 
 plest statement conceivable. The type of 
 the chemical process is found in solution, 
 from which it is possible, under changed physi- 
 cal conditions, to regenerate the original 
 species." (12.) 
 
 § 10. Chemical change, then, may be defined 
 as an integration or a disintegration of chemi- 
 cal species, resulting in the genesis of new 
 species, which are themselves chemical ; that 
 is to say, mineral, and not organic. All of 
 these " may be supposed to be formed from a 
 single element, or materia prima, by the chemi- 
 cal process." "The chemical species, until it 
 attains to individuality in the crystal, is essen- 
 tially quantitative." (10.) Gases, liquids, and 
 colloids have a specific existence, but no indi- 
 viduality ; mechanical subdivision does not 
 
 i**! 
 
 \ i 
 
 i*J 
 
i8 
 
 A CJiemical Philosophy. 
 
 destroy them. " The activities of the crystal 
 are purely dynamic, and its crystalline individ- 
 uality must be destroyed before it can be the 
 subject of chemism, while the plant and the 
 animal exhibit not only dynamical and chemical, 
 but organogenic activities, which last are desig- 
 nated as vital phenomena." All of these are 
 necessary for the preservation of the organism. 
 The study of these vital activities constitutes a 
 third division of physics, which we have else- 
 where called biotics. 
 
 ** Mineralogy is the science of inorganic mat- 
 ter, and studies its dynamical and chemical 
 relations ; while biology, which is the science 
 of organic matter, adds to these the study of 
 biotical relations. The dynamical and chemi- 
 cal activities which, in the mineral kingdom, 
 give rise to the crystalline individual, are 
 therein in static equilibrium. The organic 
 individual, on the contrary, is kinetic, and 
 maintains its equilibrium by perpetual ad- 
 justment with the outer world," ** The 
 physiology of matter in the abstract is 
 dynamical ; that of mineral forms is both 
 dynamical and chemical ; while that of organic 
 
Nature of the Chemical Process. 
 
 19 
 
 forms is at once dynamical, chemical, and 
 biotical." (14.)^ 
 
 § II. By keeping in mind the above defini- 
 tions, we shall avoid the error of modern 
 students, who are disposed to confound dyn- 
 amic activities with chemism itself, and thus 
 to lose sight of the essential nature of the 
 chemical process, which, as was pointed out in 
 1853 (§ 3), is to be clearly distinguished from 
 
 ' These relations will be made more apparent by the help of 
 a tabular view of the classification of the natural sciences from 
 the writer's Mineral Physiology and Physiography, page 29. 
 
 Natural Sciences. 
 
 Inorganic Nature. 
 
 Organic Nature. 
 
 Descriptive, 
 
 Mineral Physiography. 
 
 Biophysiography. 
 
 General Physiography 
 
 Descriptive and Systematic 
 
 Organography ; 
 
 or 
 
 Mineralogy ; 
 
 Descriptive and Syste- 
 
 Natural History. 
 
 Geognosy ; Geography ; 
 
 matic Botany and 
 
 
 Descriptive Astronomy. 
 
 Zoology. 
 
 Philosophical. 
 
 Mineral Physiology. 
 
 Biophysiologv. 
 
 General Physiology 
 
 Dynamics or Physics ; 
 
 Biotics. 
 
 or 
 
 Chemistry. 
 
 Organogeny; Morpho- 
 
 Natural Philosophy. 
 
 Geogeny ; Theoretical 
 
 logy; Physiological 
 
 
 Astronomy. 
 
 Botany and Zoology. 
 
 ■■■%• 
 
 Ij 
 
 \\ 
 
 In I 
 
 iii 
 
 .1 \ 
 
 
ii 
 
 20 
 
 A Chemical Pliilosophy. 
 
 the phenomena belonging to what we may call 
 dynamism. As examples of this prevailing 
 confusion, it was said, in 1881 : " Clifford wrote 
 of molecular motion, ' which makes itself known 
 as light, or radiant energy, or chemical action ' ; 
 while Faraday was wont ' to express his convic- 
 tion that the forces termed chemical affinity 
 and electricity are one and the same.' Helm- 
 holtz, from whom I here quote, adds : ' I think 
 the facts leave no doubt that the very mightiest 
 among the chemical forces are of electrical 
 origin . . . but I do not suppose that other 
 molecular forces are excluded, working directly 
 from atom to atom.' " Similar language might 
 be quoted from other not less eminent authori- 
 ties, to show the vague notions still reigning in 
 the minds of modern students as to the scope 
 of chemistry, and its relation to dynamics. 
 
 "The activities which appear in dynamical 
 and in chemical phenomena are one in essence, 
 for force is one. The same is true of the activ- 
 ities manifested in organic growth, and even in 
 thought ; but the unity and mutual convertibil- 
 ity of different manifestations of force afford no 
 ground for confounding, as some would do, 
 
Nature of the Chemical Process. 
 
 21 
 
 dynamics with chemism, or with vital or mental 
 processes. All these phenomena arc but evi- 
 dences of universal animation ; or, in other 
 words, of an energy which is inherent in 
 matter, the manifestations of which, as matter 
 rises to higher stages of development, become 
 more complex, as organic individuals are them- 
 selves more complex than mineral forms." 
 
 " When the energy which is in matter is 
 manifested without reference to species, we 
 call it simply dynamics ; when it results in the 
 production of mineral species, we call it chem- 
 ics, or chemism ; and when it gives rise to 
 organisms, which may be defined as kinetic 
 individuals, we distinguish it as vital, or biotic. 
 In matter we must recognize, with Tyndall, 
 * the promise and the potency of all terrestrial 
 life.'" (14.) Those dynamic activities which 
 manifest themselves as electricity, temperature, 
 and radiant energy, while attendant upon chem- 
 ical processes, are yet to be as carefully dis- 
 tinguished from the essential phenomena of 
 chemism as the latter are from those of biotics. 
 
 § 12. In farther illustration of the nature of 
 chemical combination, it was said, in 1853 : 
 
 1: 
 
 I' 
 
 
f 
 
 '11 
 
 !il 
 
 22 
 
 A Chemical Philosophy. 
 
 " Solution is a result of that tendency in nature 
 which constantly leads to unity, condensation, 
 identification." " Solution is chemical union, 
 as is indicated by the attendant condensation." 
 (4.) Again, in 1855, it was written: "All 
 chemical union is nothing else than solution ; 
 the uniting species are, as it were, dissolved in 
 each other; for solution is mutual." " Solution, 
 then, being identification, the discussion as to 
 whether metallic chlorids are changed into 
 hydrochlorates when dissolved in water is 
 meaningless. Such a solution is a unity, in 
 which we can no more assert the existence of 
 the chlorid, or of water, than of chlorine, hydro- 
 chloric acid, or a metallic oxyd ; although these, 
 and many others, are conceivable results of its 
 differentiation." (7.) In the words already cited, 
 — "The type of the chemical process is found 
 in solution, from which it is possible, under 
 changed physical conditions, to regenerate the 
 original species." (12.) 
 
CHAPTER III. 
 
 GENESIS OF THE CHEMICAL ELEMENTS. 
 
 § 13. There remains to be considered an- 
 other aspect of the chemical process — namely, 
 the production, from a primal undifferentiated 
 matter, of the chemical elements, as suggested 
 by Lorenz Oken.' " The successive steps in 
 
 ^ In this connection we quote from page 3 of Tulk's Trans- 
 lation of Oken's Physiophiiosophy, pul)lished by the Ray 
 Society in 1847, with a preface by Oken himself, the following 
 passage : " Physiophiiosophy is divisible, therefore, into three 
 parts. . . . The first division is the doctrine of the Whole 
 {i/e Toto) — Mathesis. The second that of Singulars {de Eiiti- 
 liiis) — Ontology. The third that of the Whole in Singulars 
 (de Toto in Entibiis) — Biology. The science of the Whole 
 must divide itself into two doctrines ; into that of immaterial 
 totalities — Pneumatogeny; and that of material totalities — 
 Hylogeny. Ontology teaches us the phenomena of matter. 
 The first phenomena of this are the heavenly bodies, compre- 
 hended by Cosmogony. These develop themselves further, 
 and divide [differentiate] into the elements — Stoichiogeny. 
 From these the earth-element develops itself still further, and 
 divides into minerals — Mineralogy. These minerals unite in 
 one collective body, and this is Geogcny. The Whole in 
 Singulars is the living or Organic, which again divides into 
 plants and animals." The study of these includes Biology, 
 with its subdivisions. 
 
 23 
 
 ti 
 
 -J-T- , 
 
 ilJ 
 
 ■Ul \ 
 
1 
 
 1 
 
 1' 
 
 
 H 
 
 A Chemical Philosophy. 
 
 m 
 
 the ontological process are, first, Cosmogony, or 
 the fashioning of the heavenly bodies from the 
 previously formed matter ; followed by the gen- 
 esis therefrom of the chemical elements, Stoi- 
 chiogeny." (14.) 
 
 § 14. The conception of the genesis of the 
 so-called chemical elements first took a definite 
 form from the study of the equivalent weights 
 of related elements, and from the law of num- 
 bers made apparent in hydrocarbonaccous bod- 
 ies. Of this we wrote as follows, in 1874, in 
 the essay on A Century's Progress in Theoreti- 
 cal Chemistry (12) : — 
 
 "As early as 1829, Dobereiner called atten- 
 tion to the triads of related bodies, such as the 
 groups of lithium, sodium, and potassium, and 
 of calcium, strontium, and barium, in which 
 the equivalent weight of the middle term is 
 the mean of that of the extremes. Almost 
 simultaneously, and apparently independently, 
 Pettenkofer and Dumas took up again the 
 question, in 185 1, and noticed the fact that 
 the numerical relations between these and 
 many other mineral radicles are similar to 
 those between the organic radicles known to 
 
Genesis of the Chemical Elements. 25 
 
 result from the condensation of successive 
 equivalents of carbon and hydrogen, such as 
 the olefines, the paraffines, and the alcohol 
 radicles. The possibility that the mineral 
 radicles, related alike in chemical characters 
 and in equivalent weights, might, also, be com- 
 posite bodies, was suggested by Dumas in 
 1857; and with this in view he undertook a 
 re-examination of the equivalent weights of 
 the elements. If, as the numbers adopted by 
 Berzelius seemed to show, no simple ratios 
 existed between those of related elements, the 
 suggestion of Dumas was inadmissible ; but if, 
 on the contrary, as supposed by Prout, a simple 
 and exact relation of this kind was established, 
 it was not impossible that the view of their 
 compound nature might be true." 
 
 '* The results of many years of patient labor 
 devoted to a re-examination of the equivalent 
 weights of a great number of bodies, were 
 given to the world by Dumas, in 1859; and 
 from these he concluded that the law of Prout 
 is so far true that the equivalent weights of 
 the elements are multiples of a unity which is 
 one-fourth that of hydrogen. . . . These re- 
 
 
 *m; 
 
 ;i .Jj- 
 
 
 ill \ 
 
 " ? it 1 
 
 >i 
 
 I 
 
 : f 
 
 I ! 
 
1 
 
 26 
 
 A Chemical Philosophy. 
 
 Ml 
 
 suits, and the analogies between the elements 
 of mineral and of organic chemistry, both in 
 chemical relations and in equivalent weights 
 (which in the mean time had been carefully 
 investigated and developed by J. P. Cooke), now 
 led Dumas to reafHrm his conjecture that the 
 mineral radicles may really be compounds, 
 though their decomposition is perhaps beyond 
 the possibilities of our chemical analysis." (12.) 
 
 § 15. The next step in the development of 
 the doctrine of Stoichiogeny, so far as known 
 to the writer, is to be found in his lecture of 
 1867 (11), quoted below. The history thereof, 
 and of certain views enunciated almost simul- 
 taneously by Brodie of Oxford and the present 
 writer, and subsequently developed and ex- 
 tended by the latter, is given at length in his 
 essay on Celestial Chemistry from the Time of 
 Newton (15), as follows : — 
 
 " In Part I. of his Calculus of Chemical 
 Operations, read before the Royal Society, 
 May 3, 1866, and published in the Philosophi- 
 cal Transactions for that year, Brodie was led 
 to assume the existence of certain ideal ele- 
 ments. These, he said, ' though now revealed 
 
Gcfiesis of the Chemical Elements. 27 
 
 to us through the numerical properties of chem- 
 ical equations only as implicit and dependent 
 existences, we cannot but surmise may some- 
 times become, or may in the past have been, 
 isolated and independent existences* Shortly 
 after this publication, in the spring of 1867, I 
 spent several days in Paris with the late Henri 
 Sainte-Claire Devillc, repeating with him some 
 of his remarkable experiments in chemical dis- 
 sociation, the theory of which we then discussed 
 in its relations to Faye's solar hypothesis. 
 From Paris, in the month of May, I went, as 
 the guest of Brodie, for a few days to Oxford, 
 where I read for the first time, and discussed 
 with him, his essay on the Calculus of Chemi- 
 cal Operations, in which connection occurred 
 the very natural suggestion that his ideal ele- 
 ments might, perhaps, be liberated in solar fires, 
 and thus be made evident to the spectroscope." 
 § 15 A. "I was then about to give, by invita- 
 tion, a lecture before the Royal Institution, on 
 The Chemistry of the Primeval Earth, which 
 was delivered May 31, 1867. A stenographic 
 report of the lecture, revised by the author, 
 was published in the Chemical News of June 
 
 ■' ) 
 
 1 1' 
 
 ! 3 
 
 
 HHfl 
 
 ' i-i 
 
 ■ t 
 
 j 
 
 1 
 
^IF 
 
 28 
 
 A Chemical Philosophy. 
 
 21, 1867, and in the Proceedings of the Royal 
 Institution. Therein, I considered the chem- 
 istry of nebulas, sun, and stars in the combined 
 light of spectroscopic analysis and Deville's 
 researches on dissociation, and concluded with 
 the generalization that the *breaking-up of 
 compounds, or dissociation of elements, by 
 intense heat is a principle of universal applica- 
 tion, so that we may suppose that all the ele- 
 ments which make up the sun, or our planet, 
 would, when so intensely heated as to be in 
 the gaseous condition which all matter is capa- 
 ble of assuming, remain uncombined ; that is to 
 say, would exist together in the state of chem- 
 ical elements ; whose further dissociation in 
 stellar or nebulous masses may even give us 
 evidence of matter still more elemental than 
 that revealed in the experiments of the labora- 
 tory, where we can only conjecture the com- 
 pound nature of many of the so-called ele- 
 mentary substances ' (11)." 
 
 § 16. "The importance of this conception, in 
 view of subsequent discoveries in spectroscopy 
 and in stellar chemistry, has been well set forth 
 by Lockyer, in his late lectures on Solar Phys- 
 
Genesis of the Chemical Elements. 29 
 
 ics,^ where, however, the generalization is de- 
 scribed as having been first made by Brodie, 
 in 1867. A similar but later enunciation of 
 the same idea by Clerk-Maxwell is also cited 
 by Lockyer. Brodie, in fact, on the 6th of 
 June, one week after my own lecture, gave a 
 lecture on Ideal Chemistry before the Chemi- 
 cal Society of London, published in the Chemi- 
 cal News of June 14, in which, with regard 
 to his ideal elements (in further extension of 
 the suggestion already put forth by him in the 
 extract above given from his paper of May 6, 
 1866), he says: * We may conceive that in 
 remote ages the temperature of matter was 
 much higher than it is now, and that these 
 other things [the ideal elements] existed in the 
 state of perfect gases — separate existences — 
 uncombined.' He further suggested, from 
 spectroscopic evidence, that it is probable that 
 ' we may one day, from this source, have re- 
 vealed to us independent evidence of the 
 existence of these ideal elements in the sun 
 and stars.' During the months of June and 
 July, 1867, I was absent on the Continent; 
 1 Nature, Aug. 25, 188 1, vol. xxiv. p. 396. 
 
 • i 
 
 
 1 
 
 \M 
 
 
 % 
 
 '.rx 
 
 i 3 
 
 s\ 
 
m 
 
 
 iiii 'I 
 
 30 
 
 A Chemical Philosophy. 
 
 and this lecture of Brodie's remained wholly 
 unknown to me until its republication in 1880, 
 in a separate form, by its author/ with a 
 preface, in which he pointed out that he had 
 therein suggested the probable liberation of 
 his ideal elements in the sun, referring at the 
 same time to his paper of 1866, from which 
 we have already quoted the only expression 
 bearing on the possible independence of these 
 ideal elements somewhere in time or in space." 
 " The above statements are necessary in order 
 to explain why it is that I have made no refer- 
 ence to Sir Benjamin Brodie on the several 
 occasions on which, in the interval between 
 1867 and the present time [1881], I have re- 
 iterated and enforced my views on the great 
 significance of the hypothesis of celestial disso- 
 ciation as giving rise to forms of matter more 
 elemental than any known to us in terrestrial 
 chemistry. The conception, as at first enunci- 
 ated, in somewhat different forms, alike by 
 Brodie and myself, was one to which we were 
 both naturally, one might say inevitably, led, by 
 different paths, from our respective fields of 
 
 1 Ideal Chemistry, a Lecture. Macmillan, 1S80. 
 
Genesis of the Chemical Elements. 31 
 
 speculation, and which each might accept as in 
 the highest degree probable, and make, as it 
 were, his own. I write, therefore, in no spirit of 
 invidious rivalry with my honored and lamented 
 friend, but simply to clear myself from the 
 charge, which might otherwise be brought 
 against me, of having, on various occasions 
 within the past fourteen years, put forth and 
 enlarged upon this conception without mention- 
 ing Sir Benjamin Brodic, whose only publica- 
 tion on the subject, so far as I am aware, was 
 his lecture of 1867, unknown to me until its 
 reprint in 1880." 
 
 § 17. "It was at the grave of Priestley, in 
 1874, that I for the second time considered the 
 doctrine of celestial dissociation, commencing 
 with an account of the hypothesis put forward by 
 F. W. Clarke, of Cincinnati, in January, 1873,^ 
 to explain the growing complexity which is 
 observed when we compare the spectra of the 
 white, yellow, and red stars ; in which he saw 
 evidence of a progressive evolution of chemical 
 species, by a stoichiogenic process, from more 
 
 11 
 
 If' 
 
 
 
 
 n 
 
 1 Clarke, "Evolution and the Spectroscope," Topular 
 Science Monthly, New York, vol. ii. p. 32. 
 
 ■11 
 
32 
 
 A Chemical Philosophy. 
 
 I 1 
 
 ! 
 
 elemental forms of matter. I then referred to 
 the further development of this view by Lock- 
 yer, in his communication to the French Acad- 
 emy of Sciences in November of the same year, 
 wherein he connected the successive appear- 
 ance in celestial bodies of chemical species of 
 higher and higher vapor-densities with the 
 speculations of Dumas and Pettenkofer as to 
 the composite nature of the chemical elements. ^ 
 I next quoted from my lecture of 1S67 the 
 language already cited (on page 28), to the 
 effect that dissociation by intense heat in stel- 
 lar worlds might give us more elemental forms 
 of matter than any known on earth. It was 
 further suggested that the green line in the 
 spectrum of the solar corona (which had been 
 supposed to indicate a hitherto unknown sub- 
 stance, that, * from its extension beyond even 
 the layer of partially cooled hydrogen, must, 
 according to the deductions of Mr. George J. 
 Stoney, be still lighter than this gas') may 
 be due to a 'more elemental form cf matter, 
 which, though not seen in the nebulai, is libera- 
 ted by the intense heat of the solar sphere, and 
 
 1 Lockyer, Comptes Rendus, Nov. 3, 1873. 
 
Genesis of the Chemical Elements. 33 
 
 m 
 
 ^,i:r \ 
 
 may possibly correspond to the primary matter 
 conjectured by Dumas,^ having an equivalent 
 weight one-fourth that of hydrogen.' (12.) The 
 suggestion of Lavoisier, that * hydrogen, nitro- 
 gen, and oxygen, with heat and light, might be 
 regarded as simpler forms of matter from which 
 all others are derived,' was also noticed in con- 
 nection with the fact that the nebulae, which we 
 conceive to be condensing into suns and planets, 
 have hitherto shown evidences only of the pres- 
 ence of the first two of these elements ; which, as 
 is well known, make up a large part of the gas- 
 eous envelope of our planet, in the forms of 
 air and aqueous vapor. With this I connected 
 the hypothesis that our atmosphere and ocean 
 are but portions of the universal medium which, 
 in an attenuated form, fills the interstcllary 
 spaces ; and further suggested as ' a legitimate 
 and plausible speculation,' that ' these same 
 nebulae and their resulting worlds may be 
 
 1 In the paper of 1874, it was farther said in this con- 
 nection : " Mention should also be made of the unknown ele- 
 ment conjectured by Huggins to exist in some nebulae. This 
 conception of a first matter, or Urstoff, has also been main- 
 tained by Ilinrichs, who has put forward an argument in its 
 favor from a consideration of the wave-lengths in the lines of 
 the spectra of various elements." 
 
 m 
 
 1 
 
 w 
 
 1 \ 
 
 i 
 
34 
 
 A Chemical Philosophy. 
 
 evolved by a process of chemical condensation 
 from this universal atmosphere, to which they 
 would sustain a relation somewhat analogous to 
 that of clouds and rain to the aqueous vapor 
 around us.'" 
 
 § 1 8. "These views were reiterated in the 
 preface to a second edition of my Chemical 
 and Geological Essays, in 1878, and again 
 before the British Association for the Advance- 
 ment of Science, at Dublin,^ and before the 
 French Academy of Sciences in the same 
 year.2 They were still further developed in 
 the essay on The Chemical and Geological 
 Relations of the Atmosphere, published in 
 1880 (13), in which attention was called to 
 the important contribution to the subject 
 by Mr. Lockyer, in his ingenious and beauti- 
 ful spectroscopic studies, the results of which 
 are embodied in his * Discussion of the Work- 
 ing Hypothesis that the so-called Elements 
 are Compound Bodies,' communicated to the 
 Royal Society, Dec. 12, 1878. It was then 
 remarked that the already noticed * speculation 
 
 1 Nature, Aug. 29, 1878, vol. xviii. p. 475. 
 
 2 Comptes Rendus, Sept. 23, 1878, vol. xxxviii. p. 452. 
 
Genesis of the Chemical Elements, 35 
 
 of Lavoisier is really an anticipation of that 
 view to which spectroscopic study has led 
 the chemists of to-day ' ; while it was said that 
 the hypothesis put forth by the writer in 1874, 
 ' which seeks for a source of the nebulous mat- 
 ter itself, is, perhaps, a legitimate extension of 
 the nebular hypothesis.*" (15.) 
 
 § 19. That the law of chemical dissociation 
 by heat is universal, and that in nebulous and 
 stellar masses we may expect to find more ele- 
 mental forms of matter than are known on 
 earth, was maintained by the writer in May, 
 1867. In August, 1874, connecting this con- 
 ception with the earlier speculations of Dumas 
 as to the composite nature of the so-called 
 chemical elements, and with the order of ap- 
 pearance of these in different classes of stars, 
 as noticed by Clarke, it was suggested that the 
 material from which the known elements have 
 been generated by the stoichiogenic process, 
 through successive condensations in cooling, is 
 no other than the unknown element discerned 
 by the spectroscope in the solar chromosphere, 
 as the well known line, 1474. These views, 
 which, as we have shown, have since been per- 
 
 il 
 
 1 
 
 IP 
 
 iil 
 
T-p^ 
 
 36 
 
 A Chemical Philosophy. 
 
 sistently and repeatedly asserted by the writer, 
 are now finding recognition among chemisi 
 some of whom seem to overlook the history oi 
 their origin. Such a genesis of the elements is 
 assumed by E. J. Mills, who, in 1886, writes : ^ 
 " The cooling of the primitive matter may be 
 regarded from a chemical point of view as 
 resulting in a succession of polymers (i, 2, 
 3 ...);/ ; n being the primitive density. 
 But, on account of the evolution of heat when 
 a polymer is formed, there will ensue, as :• 
 physical consequence, the inversion of more 
 less of the cooling, and therefore of the poly- 
 merization " ; a process of which it is easy to 
 trace the history, as Mills has done, in variable 
 stars. 
 
 § 20. In his address before the British Asso- 
 ciation for the Advancement of Science, in 
 September, 1886, Crookes has given a popular 
 statement of the hypothesis of the genesis of 
 the chemical elements from an intensely heated 
 primal matter, during the cooling of which they 
 have been formed by successive polymeriza- 
 
 1 Numerics of the Elements, Part II. L., E., and D. 
 Philos. Mag. xxi. 157. 
 
Genesis of the Chemical Elements. 37 
 
 tions. All of this he connects with Prout's 
 hypothesis of atomic weights, and suggests 
 that an unknown element in the solar atmos- 
 phere may be, if not the primal matter, a 
 substance having one-half the weight of hydro- 
 gen. I had already in 1874 expressed the 
 opinion that this substance might be the ele- 
 ment giving the green line, 1474, of Kirchhoff, 
 so conspicuous in the corona ; of which Young ^ 
 remarks that it would seem that "it must be 
 something with a density far below that of 
 hydrogen." Crookes, however, now suggests, 
 in 1 886, another ^ement, the hypothetical 
 helium of Franklanu, which gives the yellow 
 line D3. Still other unknown lines have of 
 late years been discovered in the solar spec- 
 trum, all of which may correspond to so-called 
 elemental species developed by the stoichi- 
 ogenic process ; and it may be a question to 
 which the primacy should be conceded. 
 
 1 C. A. Young, The Sun, 188 1 ; p. 232. 
 
 'li 
 
 m 
 
 f '^!ii 
 
 •' 'i 
 
 
 ■^ 
 
 c 
 
■^i 
 
 
 ^m 
 
 CHAPTER IV. 
 
 GASES, LIQUIDS, AND SOLIDS. 
 
 § 20. After noting, in 1853, that the equiva- 
 lents for volatile bodies are fixed from their 
 vapor-densities, and for " non-volatile species are 
 generally assumed to be those quantities which 
 sustain the simplest ratio to certain volatile 
 ones," it was said that, " having determined the 
 true equivalent of a species from the density of 
 its vapor, the inquiry arises whether a definite 
 and constant relation may not be discovered 
 between its vapor-density and the specific grav- 
 ity of a species in its solid state. Such a rela- 
 tion being established, and the value of the 
 condensation in passing from a gaFCOus to 
 a solid state being known, the equivalents of 
 solids, like tho5C of vapors, might be deter- 
 mined from their specific gravities." In an- 
 swer to the question then asked, " What is the 
 value of the condensation which takes place in 
 the change from the gaseous to the solid state, 
 
 38 
 
 I 
 
Gases, Liquids, and Solids, 
 
 39 
 
 or what equivalent corresponds to a given spe- 
 cific gravity in any crystalline solid ? " the re- 
 ceived formulas for alum, ferrocyanid of potas- 
 sium, and glucose were discussed ; and it was 
 said : ** The equivalent of a crystallized species 
 may often be a multiple of that deduced from 
 those chemical changes which commence only 
 with the destruction of its crystalline individu- 
 ality." It was added: "There are reasons for 
 believing that the equivalents of these species 
 in the crystalline state correspond to some mul- 
 tiples of the above formulas, a question which 
 is to be decided by an examination of the crys- 
 tallization and the specific gravity of species 
 whose equivalents are admitted to be higher." 
 Farther, it was said : " Favre and Silbcrmann 
 from their researches on the heat evolved in 
 fusion and solution, have been led to conckide, 
 firstly, that crystallized salts arc polymeric of 
 these same salts in solution — that is, they are 
 represented by formulas which are multiples of 
 those deduced from analysis ; secondly, that 
 double salts and acid salts do not exist in solu- 
 tion, being produced only during crystalliza- 
 tion ; and, thirdly, that water, in crystallizing, 
 
 I ! il 
 
40 
 
 A Chemical Philosophy. 
 
 changes from HO to «HO, n being some 
 whole number.^ These conclusions are seen to 
 be in accordance with those deduced from a 
 consideration of the relations of density and 
 equivalent volume. A polymerism is evident in 
 such salts as sulphate of potash and cyanid of 
 potassium, when their specific gravities are 
 compared with those of alum and the ferro- 
 cyanid." 
 
 § 21. Passing thence to the consideration of 
 the alcohols and their derivatives, it was re- 
 marked that several of those then known "have 
 very nearly the same specific gravity, so that the 
 condensation is inversely as their vapor-equiva- 
 Icnts." It was added that, in a farther study 
 of such bodies, " the specific gravity at their 
 boiling-points should probably be chosen for 
 comparison," and that we may expect to " es- 
 tablish a simple relation between the densities 
 of liquids and their vapors." (4.) 
 
 § 22. In resuming this subject in 1867, it 
 was farther said : " There probably exists be- 
 
 'M 
 
 Rccherches sur les quantitds de chaleur degagees dans 
 les actions chimiqucs et moleculaires. 1847. Comptes Rendus 
 de I'Acad. des Sciences, xxiv. 1 081-1090. 
 
Gases f Liquids, and Solids. 
 
 41 
 
 tween the true equivalent weights of non-gas- 
 eous species and their densities a relation as 
 simple as that between the equivalent weight 
 of gaseous species and their spec-nc gravities." 
 That it was possible to discover such a relation, 
 had already been maintained in 1853, when, 
 as we have seen, the doctrines of polymerism 
 and of high equivalent weights for liquid and 
 solid species had been fully set forth. The 
 chemical relation between solids, liquids, and 
 gases was now, however, first clearly defined as 
 follows : 
 
 "The gas or vapor of a volatile body con- 
 stitutes a species distinct from the same body 
 in its liquid or solid state, the chemical 
 formula of the latter being some multiple of 
 the first ; and the liquid and solid species often 
 [probably always] constitute two distinct spe- 
 cies, of different equivalent weights. In the 
 case of analogous volatile species, as the hydro- 
 carbons and their derivatives, the equivalent 
 weights of the liquid and solid species approxi- 
 mate to a constant quantity, so that the densi- 
 ties of those species in the case of homologous 
 or related alcohols, acids, ethers, and glycerids, 
 
 |i 
 
 it- i 
 
 * 
 
 Nij- 
 
 jl :: 
 
I 
 
 42 
 
 A Chemical Philosophy. 
 
 are subject to no great variations. These 
 non-gaseous species are generated by the chem- 
 ical union or identification of a number of vol- 
 umes or equivalents of the gaseous species, 
 which number varies inversely as the density of 
 those gaseous species." (10.) 
 
 In 1874, reverting to the conception of the 
 polymerism exhibited in different forms of car- 
 bon and phosphorus, as maintained in 1848 
 (page 12), it was said: "By the comparison of 
 these with substances known to possess a high 
 equivalent weight, as, for example, some organic 
 bodies, it would even be possible to fix that of 
 these elemental species ; which would certainly 
 be found to have a very elevated equivalent, 
 indicating a high degree of polymerism." (12.) 
 
CHAPTER V. 
 
 THE LAW OF NUMBERS. 
 
 § 23. The law of numbers, which is seen in 
 the doctrine of multiple proportions and in 
 polymerism, received a great extension in the 
 discovery of what have been called progressive 
 series, made known in 1842, by James Schiel, 
 and adopted by Ch. Gerhardt, in 1844, in his 
 Precis de Chimie Organique, under the name 
 of homologous series. This conception was by 
 these chemists applied only to hydrocarbona- 
 ceous compounds, differing from each other by 
 C2H2, which was shown to be the common dif- 
 ference in the formulas of certain series of 
 bodies having similar chemical relations. 
 
 As regards the farther extension of this prin- 
 ciple, and the breaking-down of the distinction 
 hitherto maintained between so-called organic 
 chemistry and mineral chemistry, it was said 
 by the writer, in 1852, that " wc may define 
 
 43 
 
j, 
 
 ■ 
 
 
 44 
 
 A Chemical Philosophy. 
 
 organic chemistry as the chemistry of the com- 
 pounds of carbon." These were then spoken 
 of as " the carbon series " ; while " the silicon 
 series " was made to include all the known 
 silicious compounds. (3.) Of the above defi- 
 nition it has been elsewhere said that, " though 
 a commonplace to-day, it was, perhaps, then 
 made for the first time." (16.) 
 
 (3.) In 1853 it was farther pointed out that 
 " C2H2 may be compared with O2H2 and with 
 O2M2" (CH2, OH2, OM2, in the present notation); 
 so that since species differing by //(CjHa) may 
 be homologous, " it may be expected that min- 
 eral species will exhibit the same relations as 
 those of the carbon series, and the principle of 
 homology be greatly extended in its applica- 
 tion," as was then shown by reference to many 
 silicates. (4.) In the same year it was also 
 said : " The formulas of homologous bodies may 
 be represented as series in arithmetical progres- 
 sion [progressive series]. The first term may 
 be the same as the common difference," as in 
 the hydrocarbons of the series //(CHg), or un- 
 like the common difference, as in the ammo- 
 nias NH3. . . . NH3.«(CH2). "Both of these 
 
The Law of Numbers. 
 
 45 
 
 cases are illustrated in the chemical history of 
 mineral species"; and "M.^Sg, M2O2, and HjOa 
 may be compared with H^Ca." The application 
 of these principles was then shown at length. 
 (5.) The members of a progressive series in 
 which the first term is the same as the com- 
 mon difference may be designated as isomeric 
 homologues ; while all other progressive series 
 are appropriately called anisomeric. 
 
 § 24. The progressive series among gaseous 
 species, except in some few hydrocarbons, are 
 examples of anisomeric homologues. To these 
 gaseous species belong all considerations as 
 to metagenesis, from the study of which have 
 grown up the so-called rational and structural 
 formulas, and the theory of types. With regard 
 to all these it is well to remember " the lan- 
 guage of Ch. Gerhardt, that they ' are not 
 intended to represent the arrangement of 
 atoms, but to make evident, in the simplest 
 and most direct manner, the relations which 
 connect bodies with one another in their trans- 
 formations.' This understood, and with these 
 reservations, they have an important place in 
 chemical teaching." (12.) 
 
 . s. 
 
 m 
 
46 
 
 A Chemical Philosophy. 
 
 The new aspects revealed by the periodic 
 law, and the discovery of the reciprocal rela- 
 tions between the properties and the combining 
 weights of the elements suffice to show that the 
 hypothesis of Prout must, at least, be greatly 
 modified before it can be received, and help, 
 moreover, to give a more profound significance 
 than was before imagined to the law of num- 
 bers in chemistry. 
 
 In 1874 the writer noticed the variations in 
 composition which J. P. Cooke, who had ob- 
 served them in certain alloys, described under 
 the name of allomerism. These alloys were 
 then regarded as "examples of a progressive 
 series of isomorphous compounds of antimony 
 and zinc, of high equivalent, differing from 
 each other by nZu^^ ' The bearing of this 
 conception on the recent views of Boutlerovv 
 and Schiitzenbergcr as to the apparent varia- 
 bility of the law of definite proportions, and 
 on Cooke's discussion thereof,^ is evident. 
 
 ' Hunt, Chemical and Geological Essays, p. 447. 
 2 American Journal of Science (1S83), xxvi. 63, 310. 
 
CHAPTER VI. 
 
 EQUIVALENT WEIGHTS. 
 
 § 25. The conception of high equivalent 
 weights for liquid and solid species, already 
 indicated in the extracts in §§ 20-22, was illus- 
 trated at length in 1853 and 1854, when the 
 carbon-spars were represented in formulas as 
 polycarbonates with from thirty to forty por- 
 tions of carbon (C = 6) ; and the pyroxenes, 
 amphiboles, and feldspars as polysilicates with 
 from thirty-two to sixty portions of silicon 
 (Si = 7). The equivalent weights thus provis- 
 ionally adopted for these species were con- 
 fessedly minima; and their relations to the 
 higher numbers of which they were supposed 
 to be fractions were left undetermined. (5, 6.) 
 Of these elevated equivalent weights and com- 
 plex formulas it was subsequently declared that 
 they do not show " a deviation from the law of 
 definite proportions," but are " only an expres- 
 sion of that law in a higher form." (10.) 
 
 47 
 
 1! 
 
 f i :i n f 
 
 .' f' I 
 
 i 
 
A Chemical Philosophy. 
 
 ^ m 
 
 m 
 
 § 26. Reverting, in this connection, to what 
 has been said in § 22, we repeat, that all liquid 
 and solid species, so far as known, may be 
 represented as polymers of some primary spe- 
 cies or chemical unit. The minimum equiva- 
 lent weights of these chemical units, which, by 
 their polymerism, give rise to higher species, 
 must often of necessity be considerable, as in 
 the case of many of the aniline derivatives, the 
 ammonio-cobalt compounds, and the polytung- 
 states. Wolcott Gibbs, who shows that these 
 latter constitute progressive series, finds the 
 common difference, which he terms the " ho- 
 mologizing term," in the phosphotungstates is 
 not less than 2(W03= 464), and shows for 
 these heavy polytungstates equivalent weights, 
 not only of 5002, but, in one case, of 20,058 ; 
 while for the less heavy ammonio-cobalt salts 
 minimum equivalent weights of from 500 to 
 2500 are deduced. Even these elevated num- 
 bers, as we shall endeavor to show, are but 
 fractions of the true equivalents of the crystal- 
 line polymeric solids, which, for the species 
 under consideration, vary from about 50,000 to 
 more than 220,000. 
 
Equivalent Weights. 
 
 49 
 
 § 27. The proofs which careful analytical 
 studies have afforded of the necessarily high 
 equivalent weights and the complex formulas of 
 the polytungstates, polymolybdates, polyvana- 
 dates, and polyphosphates, led Wolcott Gibbs, 
 in 1877, to designate them as salts of "complex 
 inorganic acids," which, according to him, 
 "form a new department of inorganic chem- 
 istry." It will be remembered that I had 
 already, in 1853, proclaimed that the whole 
 chemistry of solids and liquids is only intelligi- 
 ble when regarded as a history of just such 
 complex inorganic acids and salts ; that the 
 distinction between organic and inorganic 
 chemistry is no longer tenable ; that the 
 same principles of homology and polymerism 
 are applicable alike to the bodies of the car- 
 bon series and the silicon series ; that the 
 native crystalline carbonates, or carbon-spars, 
 are polycarbonates, with equivalent weights 
 of not less than from 1500 to 2500; that the 
 pyroxenes, feldspars, and tourmalines are poly- 
 silicates of equally complex constitution, and 
 are represented by formulas which show the 
 
 1 American Journal of Science, 1877 ; xiv., 61. 
 
 i 
 
 
 I 
 
 ill J 
 
 I 
 
 \ 
 
 I, 
 
 f- 
 
|0 
 
 A Chemical Philosophy. 
 
 existence among them both of polymers, prob- 
 ably homologous, and of anisomcric homo- 
 logucs. These conceptions, all of which were 
 explicitly set forth and defended in 1852 
 and 1853, underlie the writer's philosophy of 
 the mineral kingdom, as then enunciated, and 
 as persistently maintained to the present date. 
 The inquiry as to the value of the unit in these 
 polymers, and of the common difference be- 
 tween the successive members of these homolo- 
 gous series of polycarbonates and polysilicates 
 — whether it be the simplest admissible chemi- 
 cal unit, or some multiple thereof — is one 
 which will be considered in Chapter XI. 
 
 fr 
 
CHAPTER VII. 
 
 HARDNESS AND CHEMICAL INDIFFERENCE. 
 
 § 28. That the specific gravity of solids, lilce 
 that of gases and vapors, varies as their equiv- 
 alent weights, will follow from the principle, 
 already laid down in 1853, that chemical union 
 is essentially an identification of volumes ; or, 
 in other words, a condensation of many vol- 
 umes into one. The farther and very rational 
 deduction from this principle, that the property 
 of hardness in similarly constituted species, as 
 well as their resistance to chemical agents, 
 sustains a direct relation to the condensation, 
 was first indicated in a paper by the writer, 
 on Euphotide and Saussurite, in the American 
 Journal of Science for 1859, wherein were dis- 
 cussed the physical and chemical differences of 
 the related silicates, meionite and zoisite. In 
 referring to this in a note, " Sur la Nature du 
 Jade," presented to the French Academy of 
 
 3» 
 
 m 
 
 i^ 
 
 '■J I ' 
 
 ri 
 
 I ; 
 
52 
 
 A Chemical Philosophy. 
 
 Sciences in June, 1863, it was said, in compar- 
 ing meionite and zoisite : "The augmentation 
 of density, of hardness, and of chemical indif- 
 ference which is seen in this last species is 
 doubtless to be ascribed to a more elevated 
 equivalent ; or, in other words, to a more con- 
 densed molecule.^ These different degrees of 
 condensation, which are constantly kept in 
 mind in the study of organic chemistry, are 
 besides, as I have already elsewhere shown, of 
 great importance in mineralogy, and will form 
 the basis of a new system of classification, 
 which will be at once chemical and natural- 
 historical. The different rhombohedral carbon- 
 spars, cyanite and sillimanite, hornblende and 
 pyroxene, offer, in like manner, examples of 
 different degrees of condensation, and, by 
 their chemical composition, belong to series 
 the terms of which, like those of the hydro- 
 carbons — //(CoHo) — are both homologues and 
 
 ^ Regarding the relations between meionite and zoisite it was 
 said: " L'augmentation de densite, de diirete, ct d'indifference 
 chimique qu'on remarque dans cette derniere espece tient sans 
 doute \ un equivalent plus elev^, c'est i dire k une molecule 
 plus condensee." Comptes Rendus de I'Academie des Sciences, 
 1863, Ivi. 1256. 
 
Hardness and Chemical Indifference. 5; 
 
 multiples of the first term. At the same 
 time, each one of these silicates and carbonates 
 belongs to another possible series, the terms 
 of which differ by //(MgOi), corresponding to 
 more or less basic salts." (9.) 
 
 § 29. These relations of physical and chem- 
 ical characters to condensation were again 
 affirmed in 1867, when, after insisting on the 
 evidences of polymerism " in related mineral 
 species, such as meionite and zoisitc, dipyre 
 and jadeite, hornblende ' nd pyroxene, calcite 
 and aragonite, opal and quartz, in the zircons 
 of differci;:: densities, and in the various forms 
 of titanic oxyd and of carbon," it was said : 
 "The hardness of these isomeric or allotropic 
 species, and their indifference to chemical re- 
 agents increase with their condensation ; or, in 
 other words, vary inversely as their empirical 
 equivalent volumes, so that we here find a 
 direct relation between chemical and physical 
 properties." (10.) 
 
 § 30. The same relation of hardness to 
 condensation is evident throughout natural 
 silicates, and underlies the great distinction 
 made in the mineralogical classification of 
 
 \ 
 
54 
 
 A Chemical Philosophy. 
 
 Mohs between the order Gem, on the one hand, 
 and the order Spar, on the other. This distinc- 
 tion is made still more apparent in the division 
 which I have made the ground of tribal sub- 
 divisions running through the three sub-orders 
 of silicates, and in each separating them into 
 the gem-like or adamantoid type, on the one 
 hand, and the spathoid and hydrospathoid types, 
 on the other. Passing from these three, which 
 are all alike essentially sparry in crystalline 
 structure, to the phylloid or micaceous type, 
 the significance of the varying condensation in 
 species of this type, as regards hardness, is 
 somewhat obscured by the eminent cleavage 
 in one plane. The same is true, for an- 
 other reason, in the colloid, vitreous, or poro- 
 dic type ^ {Porodini of Breithaupt), the species 
 
 ' The term porodic (German porodisch), from the Greek 
 7Ku()6u), to harden, coagulate, or make callous, was proposed by 
 Breithaupt, in 1836 (Handbuch der Mineralogie, I. 324), as 
 synonymous with the German geronnen (curdled or clotted), to 
 designate amorphous, opal-like, gelatinous, or vitreous bodies, 
 destitute of cleavage or other marks of crystalline structure ; 
 and corresponds to the term colloid, subsequently devised by 
 Graham. Among Dorodic species Breithaupt included, be- 
 sides colloidal su)i-...»tes, phosphates, and arsenates, such 
 bodies as opal, serpentine, chrysocoUa, allophane, tachylite, 
 
Hardness and CJiemical Indifference. 55 
 
 of which — in many cases,' at least — include 
 crystalline portions belonging to sparry types. 
 The tribal distinctions above indicated are 
 farther noticed in § 32. 
 
 A similar relation between hardness and 
 chemical indifference and the degree of con- 
 densation has also been pointed out by the 
 author for the anhydrous oxyds other than 
 silicates, and for metals and their compounds 
 with sulphur, selenium, tellurium, arsenic, and 
 antimony, which make up the several tribes of 
 the sub-orders Metallometallate and Spatho- 
 metallate in the great natural order of the 
 Metallates. (16.) 
 
 § 31. The question of the relations of chem- 
 ical indifference to condensation has lately 
 received a new and important illustration from 
 the study of the silicates. That, while many of 
 these are readily attacked by fluorhydric acid, 
 some few of them resist more or less com- 
 pletely its action, has long been known. 
 
 and obsidian — substances alike of aqueous and of igneous 
 origin. Besides an order, Porodini, he subsccjuently defined 
 porodic genera in other orders. See, farther, the author's 
 Mineral Physiology and Physiography, p. 383. 
 
 
 1 
 
 ■1 ■ 1 
 
 1 
 
 1 ,. 
 
 ■1 
 
 i ] 1 H 
 
 1 
 
 if 
 
 ^ 
 
 1% 
 
 1} 
 I 
 
 lit 
 
56 
 
 A CJicmical Philosophy. 
 
 Among the latter had been noticed staurolite 
 and zircon, and, more recently, amphibole, pyrox- 
 ene, and chrysolite, — a fact of which Fouquc 
 availed himself to separate the last two spe- 
 cies from various feldspars and from vitreous 
 silicates. Mr. J. B. Mackintosh, late of Colum- 
 bia College, New York, and now of Lehigh 
 University, in extending these observations, 
 found, as he informed mc, a few months since, 
 that garnet also is indifferent to the action of 
 the acid ; a fact ascribed by me to its great 
 condensation, which I had already concluded 
 to be the cause of the similar indifference of 
 the species above named. In confirmation of 
 this view I suggested a comparison between 
 the more condensed species epidote and spod- 
 umene, on the one hand, and the less con- 
 densed iolite and petalite, on the other ; pre- 
 dicting the insolubility of the first two and the 
 solubility of the last two in fluorhydric acid. 
 This prevision was at once confirmed by 
 Mackintosh, who has since greatly extended, 
 and made quantitative, similar experiments on 
 many of the more important silicates. 
 
 § 32. In an attempt at A Natural System in 
 
Hardness and Chemical Indifference. 57 
 
 
 11 
 
 *il 
 
 1. . 
 
 
 !" \ 
 
 
 \ 
 
 
 Ax. 
 
 .1 
 
 Mineralogy, in 1885 (16), there was proposed, 
 as already noticed, for the three sub-orders into 
 which the order of Silicates was divided, a 
 classification into tribes, based in great part on 
 the different degrees of condensation ;, and it 
 may be said, in a few words, that the results of 
 Mackintosh appear in all cases to verify the 
 law of chemical indifference laid down in 1863. 
 While the Pectolitoids, including pectolite, 
 apophyllite, and calamine; the Protospathoids, 
 like willemite and wollastonite; the Zeolitoids; 
 and the various Protoperspathoids, including 
 the feldspars, scapolites, leucite, iolite, and 
 petalite, are more or less completely attacked 
 and dissolved by fluorhydric acid, the Protada- 
 mantoids, like pyroxene, amphibole, and chryso- 
 lite, resist more or less completely its action* 
 To this tribe, also, rather than to the Pectoli- 
 toids, datolitc, from its great condensation and 
 its comparative indifference to the acid solvent, 
 appears to belong. The same indifference is 
 observed in the Protoperadamantoids, including 
 garnet, epidote, zoisite, axinite, spodumcne, 
 staurolitc, and the tourmalines, besides ido- 
 crase and prchnite. In like manner, the Perad- 
 
;8 
 
 A Chemical Philosophy. 
 
 i 
 
 : 1 
 
 * i 
 
 amantoids andalusite, topaz, and cyanite resist 
 its action. Among the phylloid or micaceous 
 silicates, which are, for the most part, though 
 less hard than spathoids, highly condensed 
 species, the Protophylloid talc, and the Proto- 
 perphylloids ripidolite, margarite, zinnwaldite, 
 and muscovite resist the action of the acid ; 
 while biotite, phlogopite, and jefferisite are but 
 slightly attacked. 
 
 § 33. The rate of attack under similar condi- 
 tions varies greatly for different species. When 
 a given weight of the mineral in grains of a 
 determined size is exposed for an hour to a 
 large excess of a dilute fluorhydric acid which 
 fails to attack sensibly the more resisting sili- 
 cates, Mackintosh finds that, in round numbers, 
 from one to two per cent of amphibole, about 
 five of chrysolite, from twenty-five to thirty-five 
 of petalite, and the feldspars, albite, oligoclase, 
 and labradorite, forty-three of orthoclase, and 
 sixty-six of leucite are dissolved ; while willem- 
 ite, like the colloid species halloysite, is com- 
 pletely dissolved. The same is true of the col- 
 loid, opal, while artificial tridymite is also 
 readily attacked, but quartz is more resisting 
 
Hardness and Chemical Indifference. 59 
 
 than chrysolite. In experiments on a blast- 
 furnace slag, it was found that portions of the 
 mass, which, on slow cooling, had passed from a 
 vitreous or porodic condition to one of crystal- 
 linity, with a notable increase in density, had 
 become much less soluble in the acid. The 
 publication of the farther results of these stud- 
 ies, which are still in progress, and which Mack- 
 intosh has kindly communicated to me, will 
 constitute a most important contribution to 
 chemical mineralogy,* and a farther proof of the 
 dependence of chemical indifference on conden- 
 sation. 
 
 1 They have as yet been made known only by preliminary 
 notices, — in the School of Mines Quarterly, in July, 1S86; 
 in a paper by me, as yet unpublished, read to the Roval 
 Society of Canada, May 26, 1S86; and in an appendix to my 
 recently published Mineral Physiology and Physiography. A 
 more complete account, entitled " The Action of Hydrofluoric 
 Acid on Silica and the Silicates," was read by Mackintosh be- 
 fore the American Chemical Society, in New York, November 
 5, 1886, and appears in the new Journal of Analytical Chem- 
 istry for January, 18S7. 
 
 til 
 
 J? 
 
 J., k. 
 
 i 
 
 
 ff^ 
 
 .1 
 
 ^1 
 
CHAPTER VIII. 
 
 THE ATOMIC HYPOTHESIS. 
 
 § 34. From an early time in the history of 
 thought two distinct and opposite conceptions 
 of the intimate nature of matter have had their 
 partisans. The Pythagoreans taught the infi- 
 nite divisibility of matter, and its continuity in 
 a given mass, — a view held by Plato and Aris- 
 totle, and by Kant among modern masters. 
 The opposed doctrine of the finite divisibility 
 of matter, and the existence of ultimate mate- 
 rial particles, or atoms, taught by Leucippus, 
 can be traced to Phoenician, Hindoo, and, prob- 
 ably, to Egyptian sources. It was maintained 
 by Epicurus and his school, was lauded by 
 Francis Bacon, and adopted by Newton, though 
 controverted by Descartes, Leibnitz, and Euler ; 
 and had fallen into neglect until resuscitated in 
 this century by Dalton, in his System of Chemi- 
 
 60 
 
The Atomic Hypothesis. 
 
 6i 
 
 cal Philosophy, published in i8oS ; since which 
 time it has been accepted by most of the popu- 
 lar writers on chemistry as a necessary part of 
 the law of definite and multiple proportions 
 then unfolded by Dalton.^ The kinetic hypoth- 
 esis of the constitution of gases, which con- 
 ceives them to consist of solid, perfectly elastic 
 spherical particles, moving in all directions, 
 and actuated with different degrees of velocity 
 for different gases, first put forward by D. Ber- 
 noulli, in 1747, and adopted by many modern 
 
 1 See, for a history of the atomic hypothesis, Daubeny, 
 Introduction to the Atomic Theory, and, more concisely, 
 Odling, Watts's Dictionary of Chemistry, under " Atomic 
 Weights." Also for an extended discussion of the history of 
 the atomic hypothesis, and the arguments for and against it, 
 Whewell, History of the Inductive Sciences, vol. i. book vi. 
 chap. 5. He there declares that its doctrines, when they " are 
 tried upon the general range of chemical observation, prove 
 incapable of even expressing, without self-contradiction, the 
 laws of phenomena." " Chemical facts not only do not prove 
 the atomic theory as a physical truth, but they are not, accord- 
 ing to any modification yet devised of the theory, reconcilable 
 with its scheme." He adds that " when we would assert this 
 theory, not as a convenient hypothesis for the expression or 
 calculation of the laws of nature, but as a philosophical truth 
 respecting the constitution of the universe, we find ourselves 
 checked by difiiculties of reasoning which we cannot overcome, 
 as well as by conflicting phenomena which we cannot reconcile." 
 
 ! V. ■ I 
 
•fifi 
 
 62 
 
 A Chemical Philosophy. 
 
 ^ 
 
 in 
 
 physicists, was, according to Graham, resusci- 
 tated in our own time by Herepath, in 1847.^ 
 
 § 35. In discussing, in 1853, the nature of 
 the chemical process, as already set forth in 
 Chapter II., it was asserted that, "as chemical 
 combination is not a putting together of mole- 
 cules, but an interpenetration of masses, the ap- 
 plication of the atomic hypothesis to explain the 
 law of definite proportions is wholly unneces- 
 sary." (4.) Again, it was said that, since " the 
 volumes of the uniting species are always merged 
 in that of the new one . . . the atomic theory, 
 as applied by Dalton, which nakes combination 
 consist in juxtaposition, is ULcCnable." (5.) 
 
 § 36. " If, then, as maintained by the writer, 
 the law of volumes is universal, and if the 
 production of liquids and solids by the con- 
 densation of vapors is a process of chemical 
 union or integration, giving rise to polymers 
 the equivalent weights of which are as much 
 more elevated as their densities are greater 
 than those of the vapors which combine to 
 
 1 Graham, Chemical and Physical Researches, p. 211, note. 
 For a critical examination of this hypothesis, see Stallo, The 
 Concepts and Theories of Modern Physics, chapters iv. vii. viii. 
 
The Atomic Hypothesis, 
 
 63 
 
 pl' 
 
 Jill 
 
 form them, the application of the hypothesis of 
 atoms and molecules to explain the law of 
 definite proportions and the chemical process 
 is not only unnecessary but misleading. Ac- 
 cording to this hypothesis, which supposes 
 molecules to be built up of atoms, and masses 
 of molecules, the different ratios in unlike 
 species between the combining weight of the 
 chemical unit, or molecule (as deduced from 
 analysis and from vapor-density, H = i.o), 
 and the specific gravity of the mass are sup- 
 posed to represent the relative dimensions of 
 the molecules. Hence, the values got for sol- 
 ids and liquids by dividing these combining 
 weights by the specific gravity have been 
 called 'molecular volumes.' The number of 
 such * chemical molecules,' required to build up 
 a * physical molecule ' of constant volume 
 would, according to this hypothesis, be in- 
 versely as their size. If, however, as all the 
 phenomena of chemistry show, the formation of 
 higher and more complex species is by conden- 
 sation or integration, or, in other words, by 
 identification of volume, and not by juxtaposi- 
 tion, it if ws that the so-called molecular vol- 
 
 ifl 
 
 
64 
 
 A Chemical Philosophy. 
 
 
 ■" 5f ' I 
 
 umes arc really numbers representing the rela. 
 tive amounts of contraction of the respective 
 substances in passing from the gaseous to the 
 liquid or solid state, and are the reciprocals of 
 the coefficient of condensation of the assumed 
 chemical units," or atoms, or molecules.^ (17.) 
 
 § 37, Hence it was, that in discussing, in 
 1885, the relations of density to equivalent, 
 while we admitted the language of the atomic 
 hypothesis, and, in making use of the well 
 known formula / -t- <^/:= 7', recognized chemical 
 units or molecules, whose equivalent or combin- 
 ing weights are represented by/, we were care- 
 ful to say that differences in the density of 
 solid species " are not dependent on variations 
 in the hypothetical units adopted for conven- 
 ience in calculation, but belong to the species 
 as an integer, and correspond to a greater or 
 less condensation of its mass ; that is to say, to 
 the identification in a constant volume of a 
 greater or less number of these chemical units. 
 The very terms of atom and molecule which 
 
 1 The paper here quoted, on "The Law of Volumes in 
 Chemistry," is reprinted in the Chemical News for October 
 26, 1886. 
 
The Atomic Hypothesis. 
 
 65 
 
 we apply to these imaginary units, and to the 
 mass, are concessions to a popular terminology, 
 and are not only inadequate but, to a certain 
 extent, misleading when applied to chemical 
 operations." (16.) 
 
 § 38. The confusion which, as already pointed 
 out (§ 11), exists in the minds of many chemists 
 between dynamical and chemical activities, and 
 prevents a clear conception of the nature of the 
 chemical process, has led to the transference 
 of the atomic or molecular hypothesis from the 
 theory of dynamics to the theory of chemistry. 
 The phenomena of elasticity, of the movements 
 of gases and liquids, of temperature, of elec- 
 tricity, and of radiant energy, — in a word, all 
 the manifestations which come under the head 
 of dynamics, — are, in the opinion of many of 
 their students, most easily explained if we sup- 
 pose that the species which is the subject of 
 these phenomena has a structure, not continu- 
 ous, but made up of discrete molecules or atoms 
 of a definite and constant size, which in liquid 
 and solid bodies varies for different species. 
 
 § 39. The acceptance of this hypothesis of 
 the constitution of matter for all species, 
 

 I 
 
 66 
 
 A Chemical Philosop/iy. 
 
 whether solid, liquid, or gaseous, will be seen, on 
 reflection, to have no direct bearing on chemism ; 
 which does not consider the species as such, but 
 only its relations to the species from which it 
 has been derived, or into which it may pass, by 
 processes of specific integration or disintegra- 
 tion, either homogeneous or heterogeneous. 
 
 If it were possible to demonstrate the exist- 
 ence of a molecular structure, for example, in a 
 crystal of calcite ; to fix, as has been attempted, 
 by calculation, the dimensions and the weight 
 of the constituent molecules by the juxtaposi- 
 tion of which the crystal is built up, we should 
 have no better warrant than before for the 
 hypothesis that, in these molecules of cclcite, 
 either the unlike chemical species of carbonic 
 dioxyd and of calcic oxyd, or those others, car- 
 bon, calcium, and oxygen, into which chemical 
 disintegration can resolve the calcite, are pres- 
 ent as such. " Of the relations which subsist 
 between the higher species and those derived 
 from them we can only assert the possibility, 
 and, under certain conditions, the certainty of 
 producing the one from the other." (4.) 
 
 In . jnsidering this subject in 1874 it was 
 
The Atomic Hypothesis. 
 
 67 
 
 said: "Are we not going beyond the limits of 
 a sound philosophy when we endeavor by 
 hypotheses of hard particles with void spaces, 
 of atoms and molecules with bonds and links, 
 to explain chemical affinities ; and when we 
 give a concrete form to our mechanical concep- 
 tions of the great laws of definite and multiple 
 proportions to which the chemical process is 
 subordinated ? Let us not confound the image 
 with the thing itself, until, in the language of 
 Brodie, in the discussion of this very question, 
 * we mistake the suggestions of fancy for the 
 reality of nature, and cease to distinguish be- 
 tween conjecture and fact.' The atomic hy- 
 pothesis, by the aid of which Dalton sought to 
 explain his great generalizations, has done good 
 service in chemistry, as the Newtonian theory 
 of light did in optics, but is already losing its 
 hold on many advanced thinkers in our sci- 
 ence," (12.)' 
 
 1 The reader may ron'^ult with much advantage, in this con- 
 nection, a paper by C. R. A. Wright, On the Relations between 
 the Atomic Hypothesis and the Condensed Symbolic Expres- 
 sions of Chemical Facts and Changes known as Dissected 
 (Structural) Fornuilae, in 1872, L., E., and D. Philos. Mag. 
 (4) xliii. 241-264. See, also, for R, A. Atkinson's strictures 
 thereon, and Dr. Wright's rejoinder, ibid., 428-433, 503-514. 
 
f 
 
 i, 
 
 1 !■ ■ 
 
 1- i . 
 
 ■ i ' 
 
 CHAPTER IX. 
 
 THE LAW OF VOLUMES. 
 
 § 40. " The quantitative relation of one min- 
 eral (chemical) species to another is its equiva- 
 lent weight." (10.) As regards the relation of 
 weight to volume, it was said, in 1853: "The 
 weights of equal volumes of gases and vapors 
 are their equivalent weights ; and the doctrine 
 of chemical equivalents is that of the equiva- 
 lency of volumes. According to the atomic 
 hypothesis, these weights represent the relative 
 weights of the atoms ; and, as equal volumes 
 contain the same number of atoms, these must 
 have similar volumes, so that we come at last 
 to the equiva'oncy of volumes." The conden- 
 sation which constitutes polymcrism " evidently 
 offers no exception to the law of equivalent vol- 
 umes." (4.) Dalton, in his remarkable generali- 
 zations, which are summed up in his theory of 
 
 definite and multiple proportions, '* linked his 
 
 68 
 
mm 
 
 The Law of Vohmies. 
 
 69 
 
 discoveries with the old hypothesis of the 
 atomic constitution of matter, which is, how- 
 ever, by no means necessarily connected with 
 the great laws of combination by weight and by 
 number. It was reserved for Gay Lussac ^ to 
 make known a not less beautitui generalization, 
 by showing that in the combination of vapors 
 and gases there exists an equally simple rela- 
 tion of volumes, and that measure, not less 
 than number and weight, governs all chemical 
 changes." "All things, declares the sage,^ are 
 ordered by measure, by number, and by 
 weight." (12.) Already, in 1853, it had been 
 said : " The simple relations of volume, which 
 Gay Lussac pointed out in the chemical 
 changes of gases, apply to all liquid and solid 
 species, thus leading the way to a correct 
 
 * 
 
 ' In his Theory of Volumes, Memoires d'Arceuil, 1809, 
 ii. 207. 
 
 2 This is, of course, a free reading of the passage which 
 we have chosen fur the motto of this volume : " Omnia 
 mensura, et numero, et pondere disposuisti," Liber Sapientiae, 
 cap. xi., translated in the received English version of the 
 Bible: "Thou hast ordered all things in measure, and num- 
 ber, and weight," Wisdom, xi. 20. The Greek original of 
 this is made by Daubcny the epigraph to his Introduction to 
 the Atomic Theory. 
 
m 
 
 70 
 
 A Chemical Philosophy. 
 
 understanding of the equivalent volumes of 
 the latter." (5.) 
 
 § 41. We had thus in the development of a 
 theory of chemistry clearly defined the princi- 
 ple that the doctrine of chemical equivalents is 
 that of the equivalency of volumes; and that 
 the law of volumes is univen^al, and applies not 
 only to gases but to liquids and solids, which 
 are species distinct from their corresponding 
 vapors. We had, moreover, already, in 1853, 
 inquired ** whether a definite and constant rela- 
 tion may not be discovered between its vapor- 
 density and the specific gravity of a species in 
 its solid state," and had asked "what equiva- 
 lent corresponds to a given specific gravity in 
 any crystalline solid ; or, in other words, what 
 is the value of the condensation which takes 
 place in the change from the gaseous to the 
 solid state t " It was farther said : " Such a 
 relation being established, and the value of the 
 condensation in passing from a gaseous to a 
 solid state being known, the equivalents of 
 solids, like those of gases, might be determined 
 from their specific gravities." (4.) It remains 
 to be shown why the solution of the problem^ 
 
The Law of Volumes. 
 
 71 
 
 now offered for the first time in 1886, which 
 seems an obvious deduction from the principles 
 thus laid down in 1853, was not sooner dis- 
 covered. 
 
 § 42. The explanation is to be found in the 
 fact that, while affirming in a broader sense 
 than had before been stated the universality 
 of the law of volumes, the writer still believed, 
 in accordance with the generally received and 
 as yet unquestioned teaching of those who had 
 studied the volumetric relations of solid species, 
 that this law was conditioned in some manner 
 by crystalline form, so that the volume of 
 solids (and of liquids, also) was an arbitrary 
 and a variable quantity, instead of being, as in 
 the case of gases and vapors, an ideal unit. 
 The general principle laid down by Gmelin, in 
 his Handbook oi Chemistry, as deduced from 
 the studies of the volumes of solids, is that 
 " isomorphous substances have equal atomic 
 volumes." ^ Otto, also, in his learned review of 
 the subject, declares that Dumas, whose stud- 
 ies, in connection with Leroyer, have been the 
 point of departure for all investigations of the 
 1 Gmelin, Cavendish Society's edition, 1848, vol i. 
 
 r 
 
72 
 
 A Chemical PJiilosophy. 
 
 UEC; , 'I 
 
 ::lf|i 
 
 ! 
 
 relation between the specific gravity and the 
 chemical composition of solids, discovered that 
 the relation of equal volumes " is connected 
 with the crystalline form, as it exists only in 
 isomorphous species." He adds, in regard to the 
 formula p-T-d^=.v, ''Dumas was the first to 
 demonstrate that the value of v was sensibly 
 the same for all bodies whose isomorphous 
 relations had been established by Mitscher- 
 lich." 1 Following the line thus indicated, 
 chemists have been led to compare chiefly such 
 isomorphous groups, obtaining results which 
 have served to confirm the belief in the correct- 
 ness of this conclusion as to the significance 
 of crystalline form. 
 
 § 43. All this was before me in 1853, when I 
 wrote, with regard to " some allied and isomor- 
 phous species," that " H. Kopp, in dividing the 
 assumed equivalent weights of such bodies by 
 their specific gravities, obtained quantities which 
 were found to be equal for some of these related 
 species. These numbers evidently represent 
 the volumes of equivalents, and, in accordance 
 
 ' Otto, Chemical Reports and Memoirs o£ the Cavendish 
 Society, 1848, p. 67. 
 
The Law of Volumes. 
 
 73 
 
 with the atomic hypothesis, are said to denote 
 the atomic volumes." As regards the pub- 
 lished investigations up to that time, it was 
 then said: "Their results show that the vol- 
 umes thus calculated for related species of 
 similar crystalline form are generally identical, 
 or sustain to each other some simple ratio." 
 From the comparisons of the values of v in the 
 alums and in the hydrated sodium-orthophos- 
 phates and ortharsenates, and from other 
 examples which were apparently in accordance 
 with the teachings of Dumas as to the identity 
 of volume in related isomorphous species, the 
 conclusion was then reached that ** what are 
 called the atomic volumes of crystallized spe- 
 cies are the comparative volumes of their crys- 
 tals " (4); thus stating in other terms the con- 
 clusion of Dumas that, while isomorphous 
 substances have identical volumes, the volumes 
 in different crystalline systems were unlike ; a 
 point of view which was then illustrated at some 
 length. In 1855, I had more than one confer- 
 ence on this problem with Dumas, who had read 
 with approval, and then discussed at length, 
 my three papers of 1853 and 1854, while he 
 
«BI 
 
 If 
 
 74 
 
 A Chemical Philosophy. 
 
 ingeniously explained the apparent exceptions 
 to his law indicated in the above extracts, by 
 the principle of polymerism. 
 
 § 44. That some broader principle than 
 that involved in isomorphism underlies these 
 apparent conformities in volume was soon 
 after perceived, thoug-h but imperfectly ap- 
 prehended ; and when, in 1874, the essay above 
 quoted was republished in the writer's volume of 
 "Chemical and Geological Essays," a foot-note 
 was added to the portion from which was taken 
 the above cited passage as to the relation of 
 volume to crystalline form, saying, '* The con- 
 clusions in this paragraph may be liable to cor- 
 rection ; but I leave them as they were printed 
 twenty-one years since." It will be noted that, 
 in reviewing this subject in 1867, it was said: 
 " The variable relation to space of the empiri- 
 cal equivalent of non-gaseous species or, in 
 other words, the varying equivalent volume 
 . . . shows that there exist in different spe- 
 cies very unlike degrees of condensation " (10) ; 
 no reference being made to crystalline form as 
 in any way conditioning this condensation. 
 The teaching of Dumas and his successors in 
 
The Law of Volumes. 
 
 ;5 
 
 this field of inquiry for some years, however, 
 maintained the writer, in common with other 
 chemists, in the belief that the accident of crys- 
 talline form has some intimate relation with con- 
 densation. That the similar values of v in the 
 isomorphous species compared involve a rela- 
 tion of equivalents not then suspected, is made 
 apparent by the results of Graham's studies in 
 liquid diffusion, then made known, but not fully 
 understood even by himself ; to the considera- 
 tion of which we shall return in Chapter XII. 
 
 § 45. When we have once attained the con- 
 ception that the law of volumes is a fundamen- 
 tal and a universal law, to which all species, 
 whether gaseous, liquid, or solid, whether col- 
 loid or crystalline, and all changes of state 
 among these, are subordinated, the solution of 
 the great problem proposed in 1853, and stated 
 in § 41, is seen in the familiar processes of the 
 conversion of water into steam and of steam 
 into water. The latter is the change of the 
 vapor H2O into that polymeric liquid species 
 which, at its maximum density, is the unit of 
 specific gravity for all liquids and solids. Ac- 
 cording to the calculation in Ganot's Elements 
 
^^^^ SSSISSSSiSBBs^ ^^S 
 
 mmm 
 
 |! 
 
 ^\i 
 
 ^w$ 
 
 76 
 
 A Chemical Philosophy. 
 
 de Physique,^ based on a comparison of the den- 
 sities of steam as compared with air, and of air 
 as compared with water, the ratio between the 
 weights of equal volumes of steam at 100° and 
 760 mm. pressure, and of water at 0° is i : 1698. 
 The weights of equal volumes of air and water, 
 both at 0°, are as i : 773 ; but those of air at 
 100° and water at 0° as 0.73178:773. The 
 density of steam at 100° and 760 mm. as com- 
 pared with air under the same conditions 
 being as 0.6225 : i, it follows that the ratio 
 between the weights of equal volumes of steam 
 at 100° and water at o" is as 0.73178 X 0.6225 : 
 773 = 0.4555:773= 1:1698. 
 
 § 46. But we may approach this question 
 more directly, by calculating the specific gravity 
 of steam from that of hydrogen. Regnault 
 found for the weight of one litre of hydrogen in 
 the latitude of Paris at 0° and 760 mm. pressure, 
 0.089578 gramme, which from its expansion as 
 determined by him would at 100° be 0.065572 
 gramme. If we assume the equivalent of oxy- 
 gen as 16.0, we have for the weight of a litre 
 of steam, H2O, at 100° and 760 mm., 0.590148 
 
 1 Ganot, Atkinson's translation, fifth edition, 1872, p. 290. 
 
The Latv of Volumes. 
 
 77 
 
 gramme, and, dividing by this number the 
 weight of one litre of water at 4°=iooo.o 
 grammes, we get 1694.49. If, however, we take 
 for oxygen the number 15.9633 (the best figure 
 obtainable), we have for the weight of a litre of 
 steam at 100° and 760 mm., 0.58894 gramme, 
 and, taking this number as the divisor, obtain 
 1697.96; but, as water at 0° has a specific 
 gravity of 0.99987 (Rosetti), the ratio between 
 steam at 1000 and 760 mm. and water at 0° 
 becomes i : 1697.74. 
 
 The close approximation to the directly calcu- 
 lated ratio I : 1698 got by employing the cor- 
 rected equivalent weight of oxygen is such that 
 we may assume this figure as representing the 
 true ratio. But, in order to establish the amount 
 of condensation in the conversion of steam into 
 water, we must take the specific gravity of this 
 liquid at the temperature of condensation, 100°; 
 and this, according to the determination of 
 Kopp, is 0.95878. 
 
 1. 00000 : 0.95878 : : 1698 :,r = 1628.04. 
 
 This figure represents the number of volumes 
 of steam at 100° and 760 mm. which are con- 
 densed in one volume of water at the same 
 
 P 
 
IMAGE EVALUATION 
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 2.0 
 
 1.8 
 
 
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 1.6 
 
 
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 Corporation 
 
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 WEBSTER, NY 14580 
 
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^ 
 
 
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 ^ 
 
 

 78 
 
 A Chemical Philosophy. 
 
 temperature. The equivalent weight of H^O 
 being, according to our second calculation, not 
 18.0, but, more exactly, 17.9633^ that of water, 
 which is i628(H20) = 29,244.^ In first announc- 
 ing these conclusions, in September, 1886 (17), 
 by making HoO =: 18, the number 29,304 was 
 arrived at for the equivalent weight of water ; 
 and the same figure is given in the author's 
 Mineral Physiology and Physiography, p. xvii. 
 Ice is, perhaps, I494(H20), which corresponds 
 to a specific gravity of 0.9177. 
 
 If we take, as a close approximation, for the 
 weight of a litre of hydrogen at 760 mm. and 0°, 
 tne ordinarily received number, 0.0896 gramme, 
 we find for the same at 100°, 0.065588 gramme, 
 and for water-vapor under these conditions, 
 0.589088 gramme. The weight of the litre 
 of water at 100° being 95878 grammes, we 
 have : — 
 
 0.065588 : 958.78 :: I :t= 14,618.2. 
 
 Multiplying by two the value of x, which rep- 
 
 * This corrected value for the equivalent weight of water is 
 given in Science for November ig, in an abstract of the author's 
 coninuniication on " A I^asis for Chemistry " to the National 
 Academy of Sciences, November 9, 1SS6. 
 
The Lazv of Volumes. 
 
 79 
 
 resents the relation of weight between equal 
 volumes of H2 and water, both at 100°, we have 
 29,236.4, or very nearly that corresponding to 
 i628(H20) = 29,244. 
 
 In 1885, when the problem of fixing the 
 equivalent weights of liquid and solid species 
 had not yet been solved, it was shown that this 
 weight for certain solid species, such as the 
 salts of the cobaltic ammonias, and the poly- 
 tungstates, must be several thousand times that 
 of hydrogen (§ 26), with correspondingly large 
 equivalent volumes. Having then noticed what, 
 in the language of the atomic theory, were called 
 the unit-weight and the unit-volume (§ 48), rep- 
 resented by P and V (=/ and 7'), it was said : 
 "The relations alike of this unit-weight and 
 unit-volume to those of the molecule to 
 which it belongs are unknown. But this mole- 
 cule has, by our hypothesis, a constant volume, 
 for which an expression is yet wanting, and can, 
 so far as known, only be attained by assuming 
 as unity the number which corresponds to the 
 highest discovered value of V. The true unit 
 of molecular volume will probably still be some 
 multinle of this number." (1.6.) 
 
Hi 
 
 CHAPTER X. 
 
 METAMORPHOSIS IN CHEMISTRY. 
 
 § 47. Chemism may be comprehensively de- 
 fined as the production of new chemical species, 
 either by integration or by disintegration ; 
 and these changes, as has been farther shown, 
 may be either homogeneous or heterogeneous. 
 In heterogeneous integration two species of 
 unlike centesimal composition unite ; and in 
 heterogeneous differentiation a species is re- 
 solved into two or more unlike ones. This 
 genesis of complex species having a centesimal 
 composition unlike the parents, we have desig- 
 nated aa metagenesis, as set forth at some 
 length in Chapter II. In homogeneous chemi- 
 cal change we have the production of new 
 species by the union or integration of two or 
 more like species, either elemental, or, if com- 
 plex, of identical centesimal composition ; or 
 conversely, the disintegration of such com- 
 
 80 
 
Metamorphosis in Chemistry. 
 
 8i 
 
 pounded species into simpler and lilce forms. 
 These homogeneous chemical changes consti- 
 tute what we have distinguished as metamorpho- 
 sis in chemistry, and include both polymeriza- 
 tion and depolymerization. They have long 
 been familiar to chemists, alike in so-called ele- 
 ments and in many hydrocarbonaceous bodies, 
 as has been noticed in § 5, but their importance 
 is such as to demand a special discussion. 
 
 § 48. It has already been shown that the 
 bodies derived from gases and vapors by lique- 
 faction and sohdification are distinct species, 
 and are polymers of these; their generation 
 being by a process of homogeneous integra- 
 tion, or, in other words, of metamorphosis 
 by condensation ; while the vaporization of 
 such liquids and solids is homogeneous disin- 
 tegration, or metamorphosis by expansion. 
 For all species which are said to volatilize 
 without decomposition, — that is to say, which 
 may be converted into vapor without hetero- 
 geneous differentiation ; or which, in other 
 words, yield thereby simpler species having 
 the same centesimal composition as their par- 
 ent, — the equivalent weights are known from 
 

 82 
 
 A Chemical Philosophy. 
 
 their vapor-densitics ; and the coefficient of con- 
 densation for such liquid and solid species is 
 directly found by comparing the density of 
 these gaseous species with that of their liquid 
 and solid polymers, as already shown in the 
 case of steam, water, and ice. 
 
 When, however, we have to deal with species 
 which are too fixed in the fire to admit of vapor- 
 determinations, or with those which by heat 
 undergo heterogeneous disintegration, — as, for 
 example, sugars, carbon-spars, and hydrous sil- 
 icates, — in place of the unit-weight deduced 
 from vapor-density (as in the case of water, 
 mercuric chlorid, or sulphur), we may make the 
 simplest formula deduced from analysis serve 
 as the unit ; or, for greater convenience in calcu- 
 lation, may, in the case of oxyds and silicates, 
 assign to it a value corresponding to H = i and 
 = 8. The unit for silica thus becomes SiOg 
 = 60-7-4=15; that for alumina Al,06=i02 
 -1-6=: 17 ; and that for the magnesian silicate 
 forsterite,SiMg204 = 140-^8= 17.5. Such unit- 
 weights have been employed by the writer in 
 his late essay on A Natural System in Miner- 
 alogy (16), in the tables of which they have 
 
Metamorphosis in C/iemistry. 
 
 83 
 
 been represented by P ; while the values got by 
 dividing these numbers by the specific gravi- 
 ties have been called unit-volumes, and desig- 
 nated by V. That the units which make up 
 the polymers in such non-volatile species are, 
 however, far greater than these unit-weights 
 is apparent when we consider the highly com- 
 plex formulas, and the elevated equivalent 
 weights, to which we are led by the analyses 
 of many species, as already noted in Chapter VI. 
 § 49. To similar conclusions are we conducted 
 by the study of the phenomena of metamorpho- 
 sis in certain hydrocarbonaceous species, nota- 
 ble examples of which are seen in the alde- 
 hydes, and in the turpentine-oils. It will be 
 remembered that normal acetic aldehyde, with 
 a vapor-density corresponding to C2H4O and a 
 specific gravity of about .800, boiling at 21°, is, 
 in presence of small quantities of various re- 
 agents, such as chlorhydric acid or sulphurous 
 anhydrid, at ordinary temperatures, rapidly con- 
 verted, with considcrabh evolution of heat, into 
 paraldehyde, a liquid of specific gravity .998, 
 boiling at 124°, becoming a crystalline solid at 
 10*, and, from its vapor-density, a tri-aldehyde 
 

 84 
 
 A Chemical Philosophy. 
 
 3(C2H40). The same reagents, at low tempera- 
 tures, convert aldehyde into another modifica- 
 tion, metaldehyde, which is a crystalline solid 
 at 100°, and at a higher temperature volatilizes 
 without fusion. From the readiness with 
 which (like paraldehyde) it is, at a higher tem- 
 perature, reconverted into normal aldehyde, the 
 vapor-density of this polyaldehyde ;ir(C2H40) 
 cannot be determined. 
 
 Chloral, CjCHCyO, in like manner, readily 
 changes into a white insoluble species, meta- 
 chloral, of unknown equivalent weight, which 
 at 180° is converted into the vapor of normal 
 chloral, volatile at 95°. Still more remarkable 
 is the case of formic aldehyde, or methylene 
 oxyd, at ordinary temperatures a gas soluble in 
 water, and, as shown by its vapor-density, 
 CH20 = 30, which spontaneously changes into a 
 white, insoluble polymer. This, which is volatile 
 at 100°, melts at 152°, and its vapor, which is 
 perhaps 3(CH20), is at a higher temperature 
 metamorphosed into the normal aldehyde, which 
 polymerizes again on cooling. We have thus 
 an example of two interconvertible species of 
 identical centesimal composition, the one a gas, 
 
Metamorphosis in Chemistry. 
 
 85 
 
 soluble in water, and the other a white insoluble 
 solid. 
 
 § 50. Chemists have long distinguished 
 among the turpentine-oils a considerable num- 
 ber of species which, while having the same 
 centesimal composition, differ considerably not 
 only in chemical relations, in optical characters, 
 and in, being liquid or solid at ordinary temper- 
 atures, but in specific gravity and in boiling- 
 point. Some of these are found in nature, 
 while others are produced by the transforma- 
 tions of ordinary French or American turpen- 
 tine-oil. This, to which the formula CiqHis is 
 assigned, is readily metamorphosed by heat, 
 and by many reagents, giving rise to a large 
 number of new species. Some of these belong 
 (together with various natural oils) to the class 
 of proper turpenes, including several groups, to 
 all of which is assigned the above formula. 
 Among these natural and artificial turpenes 
 are the liquid pinenes, boiling at about 160° ; 
 the camphenes, having a similar boiling-point, 
 but forming crystalline solids below 50° ; and 
 the limonenes, liquids boiling about 175°- 177% 
 — with several other groups — each of these 
 
 It 
 
 111' 
 
 . I 
 
.6 
 
 A Chemical Philosophy. 
 
 i 
 
 including varieties or sub-species, differing in 
 optical characters and in chemical relations. 
 Besides these true turpenes arc others, re- 
 garded as sesquiturpenes (C15H24), boiling at 
 250°-26o° ; diturpene, or colophene (C20H32), 
 boiling at 300°; and poly turpenes, of still 
 higher equivalent and unknown complexity, 
 boiling above 360°. 
 
 § 51. When the vapor of turpentine-oil is 
 passed through a tube heated to low redness, 
 the products of condensation yield, besides 
 different turpenes, and colophene, a considera- 
 ble portion of a very volatile liquid, boiling 
 between 37° and 40°, with a vapor-density 
 showing it to be a hemiturpene (QH^), which 
 is designated pentine, and is apparently identi- 
 cal with what have been called isoprene and 
 valerylene. Besides these homogeneous trans- 
 formations or metamorphoses, both of integra- 
 tion and differentiation, produced by heat in 
 turpentine-oil, there is a simultaneous hetero- 
 geneous differentiation of a portion, resulting 
 in the production of a homologue of pentine, 
 namely, heptine (C-H12), and probably, also, of 
 the intermediate hexine, together with hydro- 
 
Metamorphosis in Chemistry. 
 
 ^7 
 
 carbons of the benzene-toluene scries, and some 
 permanent gases. 
 
 When pontine is heated in scaled tubes to 
 280°, it undergoes a partial polymerization, a 
 portion of it being changed into a turpene, with 
 a little colophene. When distilled in open 
 vessels, the transformation of this volatile 
 liquid into less volatile products causes the tem- 
 perature of the mass to rise rapidly, without 
 the aid of heat from without, the action some- 
 times becoming explosive. A similar rise of 
 temperature is noticed in the rapid polymeriza- 
 tion of aldehyde, and in that of ordinary turpen- 
 tine-oil, which is produced by contact with 
 sulphuric acid or with small portions of fluorid 
 of boron. ^ Wallach, who has lately reviewed 
 the history of the various turpentine-oils, and 
 the products of the polymerization of pontine 
 and turpene, has designated these as pentine 
 (CjHs) ; di-pentine, including the various tur- 
 pcnes (CjoHjo) ; tri-pentine, including also 
 
 1 See Watts, Dictionary of Chemistr}', under Turpentine- 
 Oil; also the papers of Armstrong and Tilden, Journal of 
 the Chemical Society of London, vols. 35 and 45 ; and later, 
 Wallach, Liehigs Annalen, vol. ccx.xvii., p. 277. 
 
 s 
 
 '3 
 
Ilitti 
 
 1 
 
 ■ 
 
 - 
 
 J 
 
 
 88 
 
 A CJicmical Philosophy. 
 
 
 various sub-species (Cu 24) > ^'^^ tetra-pentine, 
 or colophcnc (C20I 1^2) \ — besides the higher 
 polymers, of unknown complexity, including 
 the so-called mctaturpene. The specific grav- 
 ity of pontine (mono-pentine) is about .680 ; 
 that of the turpenes varies, but is not far from 
 .850; and that of the higher polymers is from 
 .920 to above i.oo. 
 
 § 52. The disengagement of heat, noticed in 
 the polymerization of aldehyde, of pontine, and 
 of turpentine-oil, is analogous to that, resulting 
 in vivid incandescence from internal change, 
 which takes place when many amorphous 
 bodies are heated to low redness, by which 
 change, in the language of Gmclin, they ac- 
 quire " greater specific gravity, greater hard- 
 ness, and less solubility." This incandescence 
 is observed in titanic, tantalic, molybdous, zir- 
 conic, chromic, and ferric oxyds, in magnesium 
 pyrophosphate, and in certain artificial arse- 
 nates and antimonates, as well as in native 
 minerals, like euxenite, gadolinite, and allanite. 
 Such as these were called by Scheerer pyro- 
 gnomic species, and adduced by him as evidence 
 that the granitic veinstones in which they are 
 
Metamorphosis in C lie mis try. 
 
 89 
 
 found were not formed at very elevated tem- 
 peratures.' 
 
 § 53. We have already noticed the question 
 of metamorphosis among so-called elemental 
 species, as discussed in 1S48 (§ 5). As re- 
 gards sulphur, and the threefold condensation 
 of its vapor then suggested, it will be remem- 
 bered that, as was shown by Bineau, in 1869, 
 this vapor, at temperatures approaching 1000°, 
 is expanded to that of normal sulphur. To 
 this we have a parallel in the cases of paralde- 
 hyde and metaldehyde, readily converted into 
 aldehyde, and in turpentine-oil, itself a poly- 
 mer, which may be volatilized as such, but at 
 an elevated temperature is resolved into pentine 
 (CsHg), which, as we have seen, readily passes 
 again into CioHig, and still higher polymers. 
 
 The effect of a given temperature upon a 
 vapor cannot be determined ^ priori ; while 
 sulphur and turpentine-oil volatilize as poly- 
 mers, the vapors of which undergo homogene- 
 ous differentiation only at much higher temper- 
 
 ^ See, in this connection, Gmelin's Hnndbook, Cavendish 
 Society's Edition, I. 106, 107 ; also the author's Mineral Phys- 
 iology, etc., p. 96. 
 
90 
 
 A Chemical Philosophy. 
 
 atures, the vapor of water assumes at once 
 its normal type, H20> and at higher temper- 
 atures undergoes heterogeneous differentiation, 
 or metagenesis, being resolved into hydrogen 
 and oxygen. There are, doubtless, other gas- 
 eous polymers, which, like tri-sulphur, S3, and 
 di-pentine, 2(C5H8), exist within certain limits of 
 temperature and pressure. In this connection, 
 the studies of Cagniard de la Tour, of Drion, 
 and of Andrews, on the conversion of liquids 
 into gases, are very important, and help to 
 enlarge our conceptions of this polymerism in 
 vapors under great pressure ; while farther 
 homogeneous integration, at lower tempera- 
 tures, gives rise to liquid and solid species, 
 more or less stable at the ordinary atmos- 
 pheric pressure. 
 
 § 54. The same gaseous species may yield 
 two or more liquid or solid species of different 
 degrees of density, and of different stability as 
 well, as is evinced by differences in boiling- 
 point. This is seen from the comparison of 
 the various groups of liquid and solid turpcnes, 
 or di-pentines, all of which are distinct from 
 the liquid forms alike of true pentine (mono- 
 
Metmnorphosis in Chemistry. 
 
 91 
 
 pentiiie), of tri-pentine, and of tctra-pentine, 
 and constitute different liquid polymers of 
 2(C5H8). Analogous differences are observed 
 in the isomeric butylic alcohols, which, with 
 a common vapor-density, exhibit, like the tur- 
 penes, considerable differences alike in specific 
 gravity and in boiling-point, and correspond to 
 greater or less degrees of condensation. The 
 various di-pentines are to be compared to ice 
 and water. The latter, under favorable condi- 
 tions, is a liquid of density i.ooo (nearly), even 
 at — 10°, though then readily transformed into 
 ice, with a density of 0.917. In like manner, 
 we have, at ordinary temperatures, besides the 
 unstable liquid phosphorus of density 1.77, the 
 ordinary and readily fusible species with a 
 density of 1.82, and the red crystalline species 
 of density 2.35, all of which, so far as known, 
 are directly changed by heat into the same 
 elemental or normal vapor, without gaseous 
 polymerism, precisely as both ice and water 
 pass directly into the normal vapor, H^^O. 
 
 § 55. A remarkable example of metamorpho- 
 sis in an elemental species is afforded by tin, 
 which, iis observed by Fritzsche, Oudemans, 
 
!*i '■>. 
 
 u 
 
 92 
 
 A Chemical Philosophy. 
 
 Schertel, and Richards,^ when exposed to great 
 natural cold, is changed from the white, tough, 
 malleable metal, having a specific gravity of 
 about 7.30, to a gray, brittle, crystalline body, 
 of much less density. This change takes place 
 not only in pure block tin but, as observed by 
 Richards, in ingots containing 2.5 per cent of 
 mercury, the change, at a minimum tempera- 
 ture of about — 180, gradually extending, in 
 this case, from certain centres, so as in a few 
 weeks to involve the whole mass; which had a 
 radiated structure, and was compared in aspect 
 to stibnite. Its density was found by Richards 
 to be 6.175, that of the unchanged portions 
 being 7.387. Other observers have found for 
 this altered form, with pure tin, densities of 6.0 
 and even of 5.8. Its instability makes this 
 determinatioi: difficult, since the gray, brittle 
 species is readily changed into white tin by 
 strong pressure, by a sudden blow, or by im- 
 mersion in hot water, which restores to it its 
 toughness and its original density of 7.30. The 
 
 1 Watts's Dictionary of Chemistry, Third Supplement; 
 also Richards, in Transactions American Institute of Mining 
 Engineers, xi. 221. 
 
Metamorphosis in Chemistry. 
 
 93 
 
 gray tin exhibits, alike in acid and in alkaline 
 liquids, electrical relations different from those 
 of the ordinary metal. . 
 
 This metamorphosis of tin is comparable 
 to that of water into ice by cold, or that of 
 aragonite into calcite by heat, the transforma- 
 tion in each case being one of homogeneous 
 disintegration from a denser to a lighter species. 
 It is not improbable that similar changes of state 
 analogous to this may take place in other bodies, 
 and that the temporary production of a simi- 
 larly brittle and chemically unstable form of 
 iron, under like circumstances, may explain the 
 apparently ready frangibility of that metal 
 when exposed to severe frosts. 
 
 § 56. Tn 1848 (§ 5), in calling attention to 
 the fact that sulphur-vapor in the only form 
 then known was tri-sulphur, SSS, which was 
 compared to SOO, it was suggested that ozone 
 might be tri-oxygen, OOO. It however is now 
 known that, though condensed oxygen, its 
 equivalent weight corresponds to one-half of 
 this, or to 000 doubled in volume by homo- 
 geneous disintegration. Making H^ the unit 
 of volume, we have for the vapor of tri-sulphur 
 
I! ^N 
 
 Is 
 
 m 
 
 94 
 
 A Chemical Philosophy, 
 
 Sg, and for sulphur-vapor above 500° Sj. If, 
 then, normal oxygen is O2, ozone is not Oe, 
 but O3. So, the vapor of iodine, I2 at tem- 
 peratures approaching 1500°, is, as shown by 
 Crafts, changed in great part into a species, Ij, 
 having but one-half the density which belongs 
 to normal iodine-vapor. i\ similar change, to a 
 less extent, is wrought at high temperatures in 
 bromine and chlorine, as shown by Victor 
 Meyer and others. These so-called elemental 
 gaseous species thus undergo at higher tempera- 
 tures a homogeneous disintegration, like that of 
 the vapor of di-pentine, when, by heat, it is 
 changed into pentine. 
 
 § 57. All of these, and similar changes, are 
 but examples of that law of dissociation by 
 heat, which includes alike so-called elements 
 and compounds ; and, as the writer was the 
 first to teach, in 1S67, is universal, and applies 
 to the chemistry of stellar matter. While 
 oxygen, nitrogen, and hydrogen give no evi- 
 dence of similar dissociation in our laboratories, 
 it was then suggested that they may suffer it 
 in the solar fires ; and later, in 1874, it was 
 pointed out that the unknown element, appar- 
 
Metamorphosis in Chemistry. 
 
 95 
 
 ently of great tenuity, shown by the spectro- 
 scope in the solar chromosphere, as line 1474, 
 Kirchhoff, is probably a more elemental form of 
 matter than any known on earth, if not the 
 primal element from which all others have been 
 generated, as set forth at length in Chapter Til. 
 It is not improbable that the power of flame or 
 the electric spark to effect the sudden union of 
 chlorine and of oxygen with hydrogen may be 
 due to the effect of intense heat in separating 
 momentarily into simpler form portions of 
 these gases, so that we may have in the process 
 of their combination a union of unknown ele- 
 mental and less dense species. 
 
 § 58. Whether in any case the homogeneous 
 differentiation or depolymerization of a volatile 
 condensed species will be effected at a single 
 step as, under the ordinary pressure at least, 
 is the case with water, the alcohols, and most 
 other liquids ; or whether, as with sulphur or 
 iodine, or with the gaseous polymers of pen- 
 tine and aldehyde, by two or more successive 
 steps, cannot, in the present state of our 
 knowledge, be foreseen. When, therefore, we 
 have to do with species which are not suscepti- 
 
 '^11 
 
M 
 
 I 
 
 Ml' 
 
 ^fiii 
 
 ill 
 
 m 
 
 96 
 
 A Chemical Philosophy. 
 
 ble of metamorphosis by expansion, — that is 
 to say, of integral volatilization, — we cannot, 
 in studying their condensation, know whether 
 we have to deal with the simplest possible 
 formula, or with some multiple thereof. Did 
 we not know the existence alike of mono- 
 pentine, and of its polymers, di-pentine, tri- 
 pentine, and tetra-pentine, we could not tell 
 how to write the formula of solid camphene, or 
 of liquid isoprene, pinene, limonene, or colo- 
 phene, although the equivalent weights of 
 these had already been fixed from their spe- 
 cific gravities. In other words, we could not 
 determine whether the unit by the polymeriza- 
 tion of which these liquid and solid species 
 have been generated is, in any given case, QHg, 
 C10H16, C15H04, or C20H32. In like manner, we 
 might ask whether the unit in crystalline 
 sulphur is mono-sulphur, 8=32, or tri-sulphur, 
 83 = 96. Yet the determination of these num- 
 bers, in the one case and in the other, is neces- 
 sary in order to fix the coefficient of condensa- 
 tion in liquid and solid species. 
 
 § 59. Resuming here what has been said of 
 metamorphosis, and its relations to metagen- 
 
 ■t i 1 
 
Metamorphosis in Chemistry. 
 
 97 
 
 esis, we repeat, that the systems of structural 
 formulas, and of types in chemistry, are but 
 expressions of the genealogical relations of 
 species, as deduced from a consideration of 
 the phenomena of metagenesis. This precedes 
 metamorphosis, which, by homogeneous inte- 
 gration, converts the simpler or normal species 
 into polymeric species of higher equivalent 
 weights. In these condensed species, as al- 
 ready pointed out, there is observed an increase, 
 corresponding to the degree of condensation, 
 in their power of resistance to chemical change ; 
 as shown in diminished volatility, fusibility, and 
 solubility, not less than in increased hardness. 
 Carbon dioxyd, CO2, is a gas, and only under 
 exceptional conditions gives rise to liquid and 
 solid polymers, which are rapidly depolymerized 
 at the ordinary pressure and temperature ; 
 while the corresponding silicon dioxyd, Si02, is 
 scarcely known except in insoluble crystalline 
 or colloidal polymeric forms, although it is prob- 
 able that, at a very high temperature, it assumes 
 the gaseous form of normal silicon dioxyd.^ 
 
 ' In an experiment made by the writer in September, 1885, 
 with the electrical furnace of the Messrs. Cowles, in which the 
 
i 1^ 
 
 A Chemical Philosophy. 
 
 § 60. Many complex species, when generated 
 by double decomposition in aqueous solutions, 
 remain dissolved for a greater or less time 
 before separating in an insoluble condition. 
 The interval which thus elapses before the for- 
 mation of such precipitates, as in the case of 
 ammonio-magnesium phosphate, of strontium 
 sulphate, and of gypsum, among others, is that 
 required to convert the soluble normal species, 
 by homogeneous integration, into insoluble 
 polymeric species. 
 
 Theoretically, all species may exist in their 
 normal or soluble forms ; and it is this condi- 
 tion which constitutes the nascent state of 
 bodies. The manner in which oxyds like those 
 of silicon, aluminium, and iron are not only 
 found in nature, but are separated in our labor- 
 atories in a crystalline state from aqueous solu- 
 
 current of a dynamo-electric machine, of thirty horse-power, 
 was passed through a horizontal column of fragments of char- 
 coal, mingled with pure silicious sand, while a portion of this 
 was reduced to silicon, and a still larger amount fused into a 
 glass, a small portion was found in botryoidal masses, like 
 chalcedony in aspect, adhering to the covering tiles of the fur- 
 nace, apparently fr^m direct volatilization. See Transactions 
 American Institute of Mining Engineers for 1885; and Chemi- 
 cal Ne .vs for Nov. C, 1885 ; pp. 235-236. 
 
Metamorphosis in Chemistry. 
 
 m 
 
 tions, shows that these oxyds, before passing 
 into insoluble and highly condensed polymeric 
 forms, have, like the compounds named above, 
 enjoyed a temporary solubility in water. The 
 very soluble forms of silicic, titanic, stannic, 
 tungstic, ferric, chromic, and aluminic oxyds, 
 which were especially studied by Graham, are 
 well known examples of this. That the mineral 
 silicates, sulphids, etc., found in veinstones 
 have also at one time been in similar condi- 
 tions, is evident from geognostical observations.* 
 This question was discussed by the present 
 writer in 1872, when it was said that "it will 
 probably one day be shown that for the greater 
 number of those oxygenized compounds which 
 we call insoluble, there exists a modification 
 soluble in water." The tendency of most 
 normal species to pass into polymeric or con- 
 densed forms, of greater or less stability, is a 
 fact of fundamental importance in chemistry. 
 
 1 Chemical and Geological Essays, page 223, note. 
 
[ii 
 
 .•f< 
 
 I 
 
 if- 
 II • 
 
 CHAPTER XI. 
 
 THE LAW OF DENSITIES. 
 
 § 6 1. The significance of the question raised 
 in § 58 of the last chapter will be made 
 more apparent in considering the densities of 
 some well known solid species ; as, for exam- 
 ple, the minerals included under the name of 
 calcareous spar or calcite, and consisting of 
 calcium-carbonate. In calculating, in Chapter 
 IX., the equivalent weight of water, it has 
 been shown that the direct determination of 
 the ratio between the volume of water at 0° 
 and that of steam at 100° (= i : 1698) agrees 
 closely with the number calculated from the 
 density of hydrogen gas (H = i.o), if that of 
 oxygen be taken at 15.9633 instead of 16.0, as 
 formerly admitted. This correction makes, for 
 water, into which the oxygen-value enters so 
 largely, a noteworthy difference, and gives 
 29,244 instead of 29,304, as the equivalent 
 
 100 
 
The Law of Densities. 
 
 lOI 
 
 weight of water, i628(H20)- ^^'^ species in 
 which this value enters in smaller proportion, 
 the difference is of less moment. Thus, for 
 calcium-carbonate, CCaOg, which, with 0= i6, 
 has a combining number of loo.o, we find, on 
 substituting the corrected value, 0=15.9633, 
 that the number is 99.89. 
 
 § 62. Dividing the first combining number by 
 2.735, ^s the approximate density of calcite 
 (water= i. 000), we get 100.0-7- 2.735 = 35.56 as 
 the reciprocal of the coefficient of condensation, 
 which gives 800 as the coefficient itself ; since 
 800X35.56 = 29,248, or almost exactly the 
 equivalent weight of water, and consequently 
 for the equivalent weight of calcite itself the 
 number 80,000. Substituting the second com- 
 bining number, 99.89, we obtain instead, 79,922. 
 But, since the specific gravity is directly as the 
 equivalent weight, we have for these two val- 
 ues respectively, as follows : — 
 
 29,244:80,000: : I :;ir^ 2.7325. 
 29,244 : 79,922 :: I :.r = 2.7356. 
 
 The small difference of about .003 in these 
 two calculations of the specific gravity of 
 
102 
 
 A Chemical Philosophy. 
 
 I 
 
 
 i'i.i 
 
 1^' 
 
 calcite, which includes nearly one-half its 
 weight of oxygen, being within the limits 
 of error in the ordinary determinations of den- 
 sity in solid species, may be disregarded, and 
 in studying the density of the various native 
 oxyds and silicates, the equivalent weights 
 as generally calculated, with 0=i6, may be 
 employed. 
 
 § 63. Now, while the density of any given 
 gas or vapor is constant at a given temperature 
 and pressure, that of many liquids and solids 
 of identical centesimal composition offers 
 greater or less variations, as may be seen 
 by comparing the specific gravities of the dif- 
 ferent forms of phosphorus, of tin, of the various 
 acetic aldehydes, of the turpenes, of ice and 
 water, of quartz and tridymite, of aragonite and 
 calcite, with one another, and even of different 
 examples of calcite among themselves. These 
 differences of density among related species, 
 upon which the writer has constantly insisted, 
 but which have not hitherto received the atten- 
 tion that belongs to them, are evidently con- 
 nected with the greater or less condensation of 
 matter in the species, or, in other words, with 
 
The Law of Densities. 
 
 loa 
 
 polymerization. Until, however, we had at- 
 tained to a clear conception of the greatness 
 of the condensation, and the consequent high 
 equivalent weight of such species, and of its 
 relation to their respective specific gravities ; 
 and, in accordance with what may perhaps be 
 called "the law of densities," could determine 
 the weights of liquids and solids as compared 
 with water, it was impossible to give to these 
 variations in specific gravity their true sig- 
 nificance. 
 
 § 64. It is now nearly half a century since 
 Breithaupt, by greatly multiplied and most 
 careful and delicate observations of the genus 
 Carbonites, under which he included, with other 
 rhombohcdral carbonates, the true calcites or 
 calcium carbonates, distinguished, among these, 
 numerous species and sub-species, marked not 
 only by variations in angular measurements, 
 in lustre, cleavage, and other superficial charac- 
 ters, but in hardness and in specific gravity. 
 Referring the student for details to the second 
 volume of Breithaupt's Handbuch der Mineral- 
 ogie (1841), it will be sufficient to note the 
 names and the densities of the species and 
 
 'W 
 
 
104 
 
 A CJicmical Philosophy. 
 
 sub-species of rhombohedral calcium-carbonate 
 thus defined : — 
 
 Carbonites archigonius 
 
 Sub-species C. a. levis .... 2.690-2.710 
 
 " C. a. ponderosus . . 
 
 Carbonites paroicus 
 
 Carbonites cugnosticus 
 
 Sub-species C. e. epithematicus . 
 
 " C. e. mediocris . . . 
 
 " C. e. hypothematicus, 
 
 Carbonites diamesus 
 
 Sub-species C. d. polymorphus 
 
 " C. d. mediocris . . 
 
 " C. d. syngcneticus 
 
 Carbonites mero.xeiius 
 
 Carbonites haplotypicus 
 
 Carbonites melleus 
 
 2734-2-7S4 
 2.652-2.678 
 
 2.700-2.708 
 2.716-2.720 
 2.720-2.730 
 
 2.707-2.714 
 
 2.721—2.727 
 
 2.732-2.749 
 2.689-2.705 
 2.72S-2.729 
 2.695-2.697 
 
 Of these, C. diamesus is by far the most 
 abundant and widely diffused species. The 
 hardness of these calcites varies from 4^ and 4 
 to 3I on the scale of Breithaupt, the heavier 
 being the harder species ; while the range of 
 densities observed is from 2.652 to 2.754. 
 
 § 65. Reverting to the law of densities 
 already set forth, and taking CCa03 = 99.89, we 
 arrive, for calcites of different coefficients of 
 condensation, and for aragonite, at the densi- 
 ties given on the following page. 
 
The Law of Densities. 105 
 
 It is evident that, while the Carbonites paroi- 
 CHs of Breithaupt corresponds nearly in density 
 to 775(CCa03) or 78o(CCOa3), Carbonites arc/ii- 
 gonitis, sub-species a. ponderosns, attains the 
 density of 8o5(CCa03), the other calcites cor- 
 responding to some intermediate term ; while 
 that of 86o(CCa03) agrees closely with the 
 known density of aragonite, which was referred 
 by Breithaupt to another genus, and according 
 to him includes Holocdritcs haplotypicus and 
 H. alloprismatieus. 
 
 77S(CCa03) 2.6501 
 
 78o(CCa03) 2.6672 
 
 790(CCa03) 2.7014 
 
 Soo{CCa03) 2.7356 
 
 805(CCaO3) 2.7527 
 
 86o(CCa03) 2.9408 
 
 § 66. The question here arises as to the 
 value of the polymeric unit in these calcium 
 carbonates with densities varying from 2.652 
 to 2.940. In case of acetic aldehyde and 
 the products of its metamorphosis, we are 
 enabled by vapor-densities to show that in one 
 case we have to do with C^jII^O, and in another 
 with 3(C2H40) ; while in the turpentine group 
 
 
 1 ji'i 
 
 >fc,...iili. ml 1 
 
I' il'. 'I ! 
 
 It ; 
 
 «i ■" 
 
 m 
 
 1 06 
 
 A Chemical Philosophy. 
 
 Si ii 
 
 11 
 
 I 
 
 we have in liquid pentine a condensation of 
 CfiHg; the various liquid and solid di-pentines 
 of different specific gravities and boiling-points, 
 being in like manner condensation-products 
 of 2(C5Hg). In all of these, also, the points of 
 fusion and of ebullition help to guide us. 
 When, however, we come to deal with non- 
 volatile solids, like calcite, this mode of deter- 
 mination is no longer open to us, and we can- 
 not say whether in the calcites the unit is 
 CCaOg or a multiple thereof by two, five, 
 or ten ; whether, in short, the formula for 
 the calcite of density 2.7356 is to be writ- 
 ten 8oo(CCa03), 40o(C.jCa20o), i6o(C5Ca50i5), 
 or 8o(CioCaioOoo.) Could we observe sharply 
 marked intervals in the density of various 
 calcites, corresponding to certain multiples 
 of CCaOy, they would furnish the data for 
 the determination of the problem. But in 
 this case we may, from the absence of such 
 intervals, infer the probable intervention of 
 the principle of crystalline admixtures among 
 isomorphous species, giving rise to calcites of 
 intermediate densities. This principle, first 
 clearly applied in mineralogy by Von Walters- 
 
M. 
 
 The Law of Densities. 
 
 107 
 
 hausen, in 1853, and by the writer, more fully, 
 and independently, in 1854 (6), is of impor- 
 tance within the limits then assigned to it ; 
 though, as has been elsewhere shown, its 
 application has been misconceived by Tscher- 
 mak, who some years afterwards adopted it.^ 
 
 § 6"]. In the equation p-^dz=.v, it will be 
 noted that the value of / is, for all gaseous or 
 volatile species, deduced directly from the 
 observed density of the gas or vapor, and 
 represents the specific gravity of such species, 
 hydrogen gas being unity ytX^ = 2.0) ; the same 
 value, for non-volatile species, being assumed as 
 corresponding or equivalent thereto. As ex- 
 amples, for the gaseous carbon dioxyd CO2, 
 we find / = 44 (0= 16); while for the related 
 silicon dioxyd, SiOj, which has only been ob- 
 served in solid, dense, polymeric forms, such as 
 quartz and tridymitc, we assume />== 60, which 
 is the equivalent weight of the unknown nor- 
 mal gaseous silicon dioxyd. For calcite, in 
 like manner, we assume the formula CCaOa 
 with a value for/ 100, which is the equiva- 
 
 * See Mineral Physiology and Physiography, pp. 294-296, 
 
 t 
 
 
 342. 
 
 m 
 
 M 
 
 ■i- 
 

 i,: 
 II 
 
 1 08 
 
 Bli ■ i ' 
 
 IK . 
 
 if ] 
 
 
 A CJicmical Philosophy, 
 
 lent weight of a gas or vapor less dense than 
 that of amylic alcohol. 
 
 On the other hand, d represents the density 
 as computed for liquids and solids ; for all of 
 which that of water at 4"* is taken as unity. 
 The relation d : / is, then, that of the density 
 of water to that of hydrogen gas, — the two units 
 of specific gravity, — or, in general terms, is 
 that of liquid and solid to that of gas and vapor ; 
 while V shows the contraction in passing from 
 the gaseous to the liquid or solid state or, in 
 other words, is the reciprocal of the coefficient 
 of condensation. For water, in which the value 
 of <:/=:i.ooo, it is evident that d=v, or, in 
 other words, that the reciprocal is identical 
 with the gaseous equivalent weight. We have 
 selected water as the first example, precisely 
 because its specific gravity at 4° (=1.000) is 
 made the unit of density for all liquids and 
 solids ; from which it follows that the equivalent 
 weight of its vapor, p (which is its specific 
 gravity, H = 1.000), and its reciprocal of con- 
 densation, V (taking now the corrected equiva- 
 lent weight of oxygen = 15.9633) are alike 
 17.9633. In the case of ice, however, if we 
 
The Law of Densities. i qq 
 
 take d = o.c,iy^ wc have 7' =19.5888. We 
 thus obtain : — 
 
 Water = 1628(1120) 
 Ice = 1492(1120) . 
 
 162S X 17.9633 = 29,244 
 1492 X 19.5SSS = 29,246 
 
 Xing 
 
 § 6S. The question to be settled in fi 
 
 the equivalent of water is to know its specific 
 gravity as compared with that of the same 
 vohmie of hydrogen gas, or of steam, at a com- 
 mon temperature, and at the standard pressure ; 
 for which experiment has accurately determined 
 the weight of these elastic fluids. These rela- 
 tions are conveniently shown in the following 
 table:— " 
 
 ill* 
 
 Speciks. 
 
 Hydrogen 
 
 Steam 
 
 Water 
 
 Formula. 
 
 Ha 
 H2O 
 
 i628(H20) 
 
 Grams i.\ i Litrb ' 
 100° and 760 mm. I Equivalent Weight. 
 
 0.06557a 
 
 0.588940 
 
 93^-780000 
 
 2.0000 
 
 I7.033 
 29,244.0000 
 
 It will be remembered that the contraction 
 of water in cooling from 100° to 4° suffices 
 to raise the weight of the litre to 1000 grams. 
 
 § 69. To give a farther illustration : the 
 hydrocarbon vapor butane, QIIjo = 58, con- 
 
no 
 
 A Chemical Philosophy. 
 
 P 
 
 ^ti« 
 
 I 
 
 I I : 
 
 
 \wm m^ 
 
 denses below io° to a liquid having at o° an 
 observed specific gravity of 0.600, which corre- 
 sponds to an equivalent weight of 17,546, com- 
 pared with water as 29,244. This is not far from 
 302(C4Hio) = i7,5i6, which, at its point of ebul- 
 lition, should have a specific gravity of 0.5989. 
 While the reciprocal of the coefficient of con- 
 densation for steam, ^=17.9633, that for the 
 gaseous hydrocarbon butane, with its observed 
 density, is 
 
 0.600 : 1. 000 : : 58 : 2/ = 96.66. 
 
 The value v in the formula p-^d= Vy being 
 the reciprocal of the coefificient of the conden- 
 sation suffered by the gaseous species (or the 
 hypothetical unit), having its combining weight 
 (or, in other words, its specific gravity, hydro- 
 gen gas being unity) represented by /, in pass- 
 ing to a specific gravity calculated for water at 
 4° as unity, and represented by d. We may, 
 therefore, for brevity, designate the value v thus 
 calculated for the condensed species as its 
 reciprocal number. 
 
 The density of solids, as of liquid species, 
 should for comparison, as already pointed out in 
 
 
The Law of Densities. jjj 
 
 1853 (§ 21), be taken at the temperature of their 
 formation, or, rather, at the highest tempera- 
 ture which they will sustain without chemical 
 change. This point is, however, difficult to 
 fix for many solids; and, as the coefficient 
 of expansion varies for different species, and 
 is at most not very considerable, we take, for 
 the present purposes of study, the densities of 
 these as already determined at ordinary tem- 
 peratures. 
 
i hf'^ 
 
 II' •? 
 
 1 
 
 t 
 
 
 I > ! 
 
 K ., 
 
 Ill 
 
 1 
 
 i^' 
 
 : 
 
 ! 
 ■ 
 
 ] 
 
 1 
 
 i i 
 i 
 
 CHAPTER XII. 
 
 A HISTORICAL RETROSPECT. 
 
 § 70. Of the fundamental conceptions em- 
 bodied in the scheme of chemical philosophy 
 set forth in the preceding pages, there are two 
 which have a historic interest apart from the 
 record of them in the writer's earlier papers. 
 These are : (i.) The doctrine of high equivalent 
 weights and complex formulas for all liquid 
 and solid species, dependent on homogeneous 
 integration or so-called polymerization, and the 
 direct connection of this, not only with hard- 
 ness and insolubility, or chemical indifference, 
 but with specific gravity ; which, it has been 
 maintained, varies for liquids and solids, as 
 well as for gases and vapors, directly as 
 the equivalent weight. (2.) The doctrine 
 that liquefaction, solidification, vaporization, 
 and the condensation of vapors, as well as 
 
 solution, — in short, all changes of state in 
 
 112 
 
■A Historica! Retrospect. j,, 
 
 inorganic species, -are cliemical clun^-es It 
 ■s proposed in the present chapter to notice 
 how far these conceptions have been enter- 
 tamed, and to what extent they have been 
 advanced, by others previous to or durin- the 
 Penod of the development of the scheme 
 wh:ch, after a growth of thirty-eight years, 
 >s now for the first time resumed and stated in 
 a completed form. 
 
 § 71. The conceptions of high equivalent 
 
 weights and of polymerism in solid species, as 
 
 deductions from thermo-chemical studies, were 
 
 .ndicated in a general way by Favre and Silber- 
 
 mann, in ,847, whose conclusions were cited by 
 
 he wmer in his more detailed exposition of 
 
 *7';";""«53(§-'°)- Graham, also, clearly 
 
 stated the notion of such polymers, though 
 
 only as existing in solutions, in ,849, as a de- 
 cluct.on from his studies in diffusion, as will be 
 shown farther on, in J 83. Their existence was 
 mamtamed on other grounds, by the writer, for 
 
 species, both complex and 
 
 elemental. 
 
 in 1S48, and aG:ain 
 
 and 1874, as already recounted 
 chapters. 
 
 in 1853, 1867, 
 
 in preceding 
 
 WA 
 
 Vi^l 
 
 ■11 
 
 Hi 
 
 J ^Hy 
 
 1 
 
 1 
 
^m 
 
 !i ^ 
 
 ' 
 
 fi 
 
 il 
 
 1 
 
 !' 
 
 ■ 
 
 r 
 
 N 
 
 111 
 
 j; 11! 
 
 
 il >; 
 
 114 
 
 ^ Chemical Philosophy, 
 
 Spencer Pickering, who does not seem to be 
 aware of their previous history, has set forth 
 similar views, but only so far as regards poly- 
 merism, and the consequent high equivalent 
 weights, in an essay on The Molecular Weights 
 of Liquids and Solids, in 1885.^ Therein, after 
 declaring that " considerations based on the 
 crystalline form and C'ther physical properties 
 of bodies force upon us the conclusion that 
 liquid and solid molecules are in all probability 
 of a very complicated nature, — certainly, more 
 complex than gaseous molecules," — he writes 
 that " the molecule of the chemist is not neces- 
 sarily identical with the molecule of the physi- 
 cist " ; and supposes that chemical molecules 
 may " agglomerate and act in unison as regards 
 certain physical forces." That such an ** ag- 
 glomerate does not act as a unit towards chemi- 
 cal forces " shows, according to Pickering, that 
 " the force which unites the individuals consti- 
 tuting it is not chemical force, or is chemical 
 force of such a weak nature " as to oppose no 
 
 1 Proceedings of British Association for the Advancement 
 of Science, in the Chemical News for November 13 and 
 20, 1885. 
 
A Historical Retrospect. 
 
 i^i 
 
 Iment 
 and 
 
 perceptible resistance to ordinary chemical 
 agents. We have here, in a mechanical form, 
 and in the language of the atomic hypothesis, 
 a reproduction of the views put forward by the 
 present writer, in his early paper of 1853, as to 
 the polymerism and high equivalent weight of 
 liquid and solid species. 
 
 § 72. Pickering's paper was presented to the 
 British Association for the Advancement of 
 Science in 1885, at the same time with one by 
 Guthrie on Physical Molecular Equivalents. 
 He therein calls attention to bodies previ- 
 ously studied by himself, and designated by 
 him as cryohydrates and subcryohydrates ; 
 which may be described as very fusible, defi- 
 nite crystalline compounds, containing many 
 portions of H2O to a single portion of a salt or 
 alkaloid. In these potassium nitrate is said 
 to be combined with 44.6(HoO), and potassium 
 sulphate with 1 14.2 (HoO) ; while diethylamine 
 forms a well defined and crystalline compound 
 with 27(H20). Guthrie conceives that in these 
 compounds the " constituents arc not in the 
 ratio of any simple multiples of their chemical 
 equivalents." A similar conception is by him 
 
 i 
 
 WM 
 
 .1 
 
 
 II' ;■ 
 
 , t: 
 
 i 
 
 ii 
 
ii6 
 
 A Chanical Philosophy. 
 
 •:1 
 
 ^V\ 
 
 extended to certain metallic alloys, which, from 
 their ready fusibility, he designates, like these 
 cryohydrates, as "eutectic." ^ 
 
 § 'j'}^. On the other hand, Messrs. Tilden and 
 Shenstonc, in their studies of the great solu- 
 bility in water of salts when near their melting- 
 points, have described compounds which, unlike 
 the cryohydrates, are homogeneous liquids, con- 
 taining, in the case of somewhat fusible com- 
 pounds, like silver nitrate and benzoic acid, 
 very small proportions of water ; from which 
 the experimenters are led to conjecture for 
 bodies an indefinite solubility in water under 
 proper conditions of temperature and pressure.^ 
 It is, however, easy to understand from the 
 high equivalent weights of such dense liquids 
 (which from their viscosity are probably col- 
 loidal) that compounds with water may exist 
 in which the proportion of the latter, though 
 definite, is so small a fraction that it would be 
 neglected in the ordinary processes of analysis. 
 
 m 
 
 * Fred. Guthrie, on Physical Molecular Equivalents, Na- 
 ture, Nov. 6, 1885 ; also on Eutexia, L., E., and D. Philosoph- 
 ical Magazine, 1884, xvii. 262. 
 
 2 Philosophical Transactions, 1884; part I., pp. 23-36. 
 
A Historical Retrospect. 
 
 117 
 
 )ugh 
 
 be 
 
 ^sis. 
 
 I, Na- 
 
 3oph- 
 
 The subject of these compounds is discussed 
 by the writer in his Mineral Physiology and 
 Physiography, pp. 221-222, and also p. 245, note; 
 where the geological significance of small por- 
 tions of water in combination under high pres- 
 sure in molten silicated rocks is insisted upon. 
 
 These two cases of apparently homogeneous 
 compounds, — on the one hand, liquids existing 
 at high temperatures, with very small propor- 
 tions, and, on the other, solids at low tempera- 
 tures, with very large proportions of water, — 
 are like illustrations of the complex formulas 
 and high equivalent weights which we have so 
 long maintained. So far from being, as con- 
 jectured by Pickering, and by Guthrie, com- 
 pounds in some sense outside of the domain 
 of chemistry, their constitution, as was said of 
 similar cases in 1867, does not present "a 
 deviation from the law of definite proportions," 
 but " is only an expression of that law in a 
 higher form." (10.) 
 
 § 74. A broader view, and a more complete 
 comprehension of the great problem under con- 
 sideration, is shown in a remarkable paper by 
 Professor Louis Henry, of the Catholic Univer- 
 
 
 i 
 
 iilU 
 
 ilii 
 
ii8 
 
 A Chemical Philosophy. 
 
 i t 
 
 ttii 
 
 i \ 
 
 sity of Louvain, published in August, 1885, 
 on The Polymerization of Metallic Oxyds,^ in 
 which, though without any reference to the 
 present writer's publications, will be found 
 developed alike the conception of polymerism 
 in liquid and solid species, and the dependence 
 thereon, not only of hardness and chemical in- 
 difference, but of specific gravity. In fact, 
 most of the important conclusions announced 
 in the author's publications from 1848 to 1867, 
 inclusive, arc set forth in the language of the 
 atomic hypothesis by Henry in his recent 
 paper. 
 
 He explains the generation of complex oxyds 
 by the union of several equivalents of hydrates, 
 and the successive elimination of equivalents 
 of water, as caught by Adolphe Wurtz in 
 i860, in discussing the origin of polysilicates.^ 
 
 ^ London, Edinburgh, and Dublin Philosophical Magazine 
 (5) XX. 81-117. This essay escaped the notice of the writer 
 until October, 18S6; otherwise it would have been noticed in 
 referring in Science for Sept. 10, 1886, to the paper of Spencer 
 Pickering, when the mode of fixing the value of the coeffi^ 
 cient of condensation for liquids and solids was first set forth, 
 as shown in § 46. 
 
 ^ See the author'^ Mineral Physiology and Physiography, 
 p. 298. 
 
A Historical Retrospect. 
 
 119 
 
 it P' -. 
 
 li r !| 
 
 While the chlorids of carbon, silicon, titanium, 
 and aluminium are species readily converted 
 into vapors of normal density ; and while car- 
 bonic dioxyd is a gas, only changed into a 
 liquid form under great pressure, the oxyds of 
 silicon, titanium, and aluminium are fixed and 
 solid bodies, of greater or less density and hard- 
 ness, and are polymers of the elemental oxyds. 
 These, in their more highly condensed forms, 
 " show a greater resistance to the action of 
 chemical agents than in their former condition, 
 in bome cases even entirely resisting the 
 action of acids and alkalies." Henry concludes 
 that " the true oxyds, which are really compara- 
 ble with the chlorids, are unknown, and that 
 we possess only polymers of these, (RO,r);/." 
 The condensation of these varies, " but appears 
 to attain its maximum in certain fixed and very 
 infusible oxyds, such as silica, alumina, etc. 
 . . . This enormous condensation of their mole- 
 cules may possibly be the cause of the greater 
 resistance which they offer to the action of 
 simple chemical agents, such as hydrogen, 
 carbon, sulphur, etc " 
 
 § 75. Henry next suggests that " the specific 
 
 b 
 
I20 
 
 A Chemical Philosophy. 
 
 \i i 
 
 gravity of a solid body doubtless depends in a 
 great measure on the state of aggregation, and 
 is also intimately connected with the composi- 
 tion of the body, and the size of the molecular 
 weight " ; adding " the density then is, to a cer- 
 tain degree, a function of the molecular weight." 
 Having reached this point, he proceeds as fol- 
 lows : "What, now, is the true value of the 
 coefficient n of polymerization ? What is the 
 real molecular formula of these polymeric 
 oxyds ? These questions arc, doubtless, of 
 great interest ; but it should be stated at once 
 that it is absolutely impossible to give a direct 
 answer. I do not know of any fact which 
 would allow us to assign an absolute value 
 to the coefficient ?i of polymerization. ... So 
 far as facts will permit a conclusion, we may 
 affirm that in most cases this number is very 
 high, although different for different oxyds." 
 
 § ^6. The problem of the value of the con- 
 densation in passing from the gaseous to the 
 solid state, as presented by Henry, in 1885, 
 is thus precisely that put forth by the present 
 writer in 1853, when he asked for a determina- 
 tion of the coefficient of condensation, and at 
 
 Mfi 
 
A Historical Retrospect. 
 
 121 
 
 the same time affirmed more positively than 
 is done by his successor in 1885, that the 
 density in liquids and solids varies directly 
 as the equivalent or so-called molecular weight. 
 (§ 41.) The direct relations of this condensa- 
 tion to hardness, and to chemical indifference, 
 were, moreover, as we have seen in preceding 
 chapters, clearly formulated by the present 
 writer, in 1863, and even in 1848 were sug- 
 gested in the case of the forms of phosphorus, 
 etc. The problem of fixing the coefficient of 
 condensation thus put forth, although not an- 
 swered, in 1853, and again propounded, and 
 declared unsolved, by Henry, in 1885,^ has, it 
 is believed, been successfully resolved in the 
 preceding chapters. 
 
 1 Henry has given, in his paper, the following valuable 
 classification of oxyds, considered with reference to polymeri- 
 zation : — 
 
 A. Normal oxyds, as SO 2, CO2, NO. 
 
 B. Polymerized oxyds, consisting of // molecules of the 
 
 normal oxyds united. 
 I. Volatile oxyds. totally depolymerized by heating, and 
 converted into the normal oxyd. 
 a. Completely depolymerized on volatilization, and 
 yielding a vapor of normal density, as S()3, OSO4, 
 methylene oxyd (CII^O);/, metaldehydc(C2ll40)3. 
 
 m 
 
m ) 
 
 122 
 
 A Chemical Philosophy. 
 
 ||ll 
 
 L 
 
 § TJ. We must here notice an essay which 
 appeared in 1876, entitled Geometrical Chem- 
 istry, by Prof. Henry Wurtz/ of New York, in 
 which he insists on the great significance of 
 density, and of the variations therein, as ob- 
 served in liquid and solid species. He asserts 
 (evidently excepting the temporary changes 
 which depend on variations in temperature) 
 
 b. Incompletely depolymerized at the moment of volatil- 
 ization, the process being completed progressively, as 
 the temperature rises. The vapor-density of these 
 gradually diminishes with increase of temperature, up 
 to a certain point, beyond which it becomes constant, 
 and corresponds to the normal oxyds; N2O4, fatty 
 acids, and paraldehyde, which last, at low tempera- 
 tures, corresponds to (C 2 1140)3, but at higher tem- 
 peratures becomes (C2H4O). [In this category, we 
 may place the elemental species iodine, bromine, and 
 chlorine.] 
 
 2. Volatile oxyds, incompletely depolymerized .it tempera- 
 tures to which they have been subjected, as (AsjOjja. 
 The volatilization of solid arsenious oxyd, at 200°, 
 without fusion, is the change of (As203)« into (As203)2. 
 
 3. Oxyds not capable of depolymerization. 
 
 a. Fixed oxyds, like SiOa, MgO, AI2O3, Fe203' 
 
 b. Oxyds volatile or decomposed by heat, as ^IgO, 
 AgjOi MnOa, CrOs ; also, organic oxyds decomposed 
 by heating. 
 
 ^ Geometrical Chemistry, by Henry Wurtz, pp. 73, reprinted 
 from the American Chemist for March, 1S76. 
 
 w 
 
;t i I 
 
 A Histot ical Retrospect. 
 
 123 
 
 that " change of volume or of density in a 
 specific liquid, or a specifically solid body, 
 whether elementary or compound, — even when 
 occurring without change of crystalline system, 
 — is an infallible indication of change of molec- 
 ular structure, and, consequently, of chemical 
 nature." Without attempting to grapple with 
 the problem of the direct relation of density in 
 such bodies to their equivalent weights, as 
 propounded by the writer in 1853, and again 
 by Louis Henry in 1885, Wurtz, nevertheless, 
 sought to frame, in accordance with the atomic 
 hypothesis, an explanation of the densities of 
 liquid and solid species. To this end he con- 
 structed for these chemical formulas, which, 
 from their frequent complexity, seem to imply 
 polymerism and high equivalent weights. We 
 find, however, on farther examination, that the 
 weights adopted by him do not represent those 
 deduciblc from these formulas, but are the sim- 
 plest combining numbers, — hydrogen being 
 unity, — multiplied, however, by 1000, to avoid 
 fractions. 
 
 § 78. Regarding chemical species as built up 
 by the agglomeration or juxtaposition of ele- 
 
 III 
 
^ 
 
 \li 
 
 I 
 
 124 
 
 A Chemical PJdlosophy. 
 
 mental molecules, Wurtz supposes that similar 
 molecules entering into a compound may pos- 
 sess unlike volumes, and to this attributes the 
 variations in the density of isomeric species. 
 The elemental molecules in his hypothesis have 
 different diameters, represented by integers 
 from 12 to 40, the cubes of these numbers 
 being the volumes of the molecules. These 
 diameters for the metals, hydrogen, and phos- 
 phorus, are very variable ; while for sulphur, 
 chlorine, bromine, and iodine, they are pretty 
 constantly 28 or 24 ; the latter being the diame- 
 ter for chlorine in chlorates and in all monad or 
 dyad chlorids. This being conceded, he ap- 
 plies to any liquid or solid species the formula 
 p-i-d=.z\ and thus gets what has been called 
 its molecular volume, multiplied, like its com- 
 bining weight/', by 1000. Taking now as an ex- 
 ample, liquid chlorhydric acid, with a combining 
 weight for H CI =/= 36,500, and an observed 
 density of 1.27, we get 2^=28,516. Deducting 
 from this the volume of €1 = 24^—13,824, 
 there remains for the volume of H = 14,692, 
 which, as he notes, is "almost identical with 
 the mean figure between 24^ and 25V' whence 
 
A Historical Retrospect. 
 
 125 
 
 he concludes that " liquid hydrochloric acid must 
 be H2CI2, containing H with the two diameters 
 
 24 and 25," and that its " volumic or molecular 
 formula" must be represented accordingly. 
 But the volume, as deduced from this formula 
 = (24^ X 3) + (25^) = 57,097, is, as near as the 
 method will admit, double the value of v ; so 
 that the " molecular formula," as understood by 
 Wurtz, corresponds not to H2CI2, with two 
 diameters for the two molecules of H2, but to 
 a mean between HCl with H = 24 and HCl 
 with H = 25. 
 
 § 79. In like manner, sodium chlorid with 
 density 2.25 is represented by NaCl, in which 
 the diameter of the molecule of sodium = 23; 
 while that with density 2.18 is supposed to be 
 represented by NajCla ,in which we have so- 
 dium with the two diameters of 23 and 24. 
 The same chlorid with density 2.05 is Na2Cl2, 
 having for sodium the two diameters 24 and 
 
 25 ; potassium chlorid, with density 2.01, being 
 K2CI2, with the diameters 28 and 29 for the two 
 potassium molecules. Similarly, phosphorus 
 with density 1.797 is supposed to consist of 
 one molecule with a diameter of 25, and five 
 
 ! f^ 
 
Ur i 
 
 ^ 
 
 
 ir 
 
 
 iiA 
 
 126 
 
 ^ Chemical Philosophy. 
 
 molecules with a diameter of 26 ; while metal- 
 loidal phosphorus, with density 2.297, includes 
 one molecule of 23 and four of 24. In these 
 cases of apparently complex formulas, however, 
 as in the case of chlorhydric acid, the value 
 adopted for/ is not a multiple, but the number 
 representing NaCl or P. Thus, for metal- 
 loidal phosphorus, described above as made up 
 of five molecules of P, and with a density of 
 2.297, we have, with /=: 31,000, a value for v 
 = 13,495. But (248) X 4 + (23') = 67,463 "^ 
 5 = 2^=13,492; while/ -^- £^=:^=: 2.297, the 
 observed density. 
 
 § 80. By thus adding together at pleasure 
 the cubes of any number of integers between 
 1 2 and 40, and dividing the sum by this num- 
 ber, in order to obtain a mean value wherewith 
 to divide the combining weight of the species, 
 it is evident that we may arrive at a near 
 approximation to the value of v as found for 
 any observed density of a given species, and 
 therefrom get by calculation a closely corre- 
 sponding density. The assumption, however, 
 that V represents the volume of the composite 
 molecule generated by the putting together of 
 
A Historical Retrospect. 127 
 
 elemental molecules is, as we have sought to 
 show, unfounded ; while the other assumption 
 that the diameters of these are represented by 
 the integers above indicated is gratuitous. 
 There is no apparent relation in the nature of 
 things between these integers and the amount 
 of contraction suffered, for example, by the 
 gaseous species HCl, with a specific gravity = 
 36.5 (hydrogen being unity), in passing into the 
 liquid species, having a specific gravity of 1.27 
 (water being unity) ; and we must regard the 
 calculations of density, and of chemical consti- 
 tution, arrived at by the above method as illu- 
 sory and essentially fallacious. 
 
 Moreover, as we have elsewhere said, while 
 calling attention to the importance of the 
 study of the densities of liquids and solids, so 
 well insisted upon by Wurtz, " the conception 
 that the chemical elements enter as such into 
 combination, and there retain their volumes, 
 appears to be inadmissible in chemical philoso- 
 phy." (16.) 
 
 § 81. Proceeding now to consider the his- 
 tory of the conception that all changes of state, 
 such as solution, fusion, solidification, vaporiza- 
 
 
 Hi 
 
PI" 
 
 
 
 I 
 
 128 
 
 A CJicmical Philosophy. 
 
 tion, and the condensation of vapors, are chemi- 
 cal in their nature, we arc led to review the 
 phenomena of gaseous and liquid diffusion, as 
 definitely set forth by Graham, in 1849. The 
 diffusion of salts from their solutions into pure 
 water was by him compared to the diffusion of 
 gases, and to the evaporation of liquids into the 
 atmosphere. " The analogy of liquid diffusion 
 to gaseous diffusion is borne out in every char- 
 acter of the former which has been examined," 
 according to Graham ; while diffusion was 
 farther said to be " a property of a fundamen- 
 tal character, upon which other properties 
 depend, like the volatility of substances," 
 "The number of species that are soluble, 
 and therefore diffusible, appears to be much 
 greater than the number of volatile bodies." 
 ** Separations, both mechanical and chemical 
 (decompositions), are produced by liquid, as 
 well as by gaseous diffusion." "Liquid diffu- 
 sion, as well as gaseous evaporation, may pro- 
 duce chemical decompositions." "The diffu- 
 sion of a salt appears to try its tendencies to 
 decomposition very severely." 
 
 § 82. The above citations are from Graham's 
 
A Historical Retrospect. 
 
 129 
 
 Bakerian Lecture on Diffusion, in ,849. From 
 h.s extended studies of this subjeet up to that 
 date, he was led to conclude that there exist 
 groups of equi-diffusive substances, which coin- 
 CKle, m many cases, with the isomorphous 
 groups but, on the whole, are more comprehen- 
 s.ve than the latter. Moreover, for several 
 groups of salts, it was found that the squares 
 of the t,mes of equal diffusion from solutions of 
 the same strength stand to each other in a 
 simple numerical relation. The squares of the 
 times of equal diffusion of gases, as Graham 
 had shown, are to one another in the ratio of 
 the,r densities. From this, by analogy, ,,e 
 ■n erred that the molecules of these several 
 sa ts as they exist in solution, possess densities 
 which are to one another as the squares of their 
 times of diffus.on. These he called their 
 solut,on-dcnsities. which, for the sulphate, ni- 
 trate, and hydrate of potassium, for example 
 
 were found to be as 4 : , ■ , • teinc ,1,. 
 , t ■ - . i , oeing the squares 
 
 of 2, 1.4,43 and I, the numbers representing 
 the relative times occupied in the diffusion of 
 equal weights of these three species, 
 § H Graham thus constructed a scale of 
 
 . ^1 
 
 ■ 
 
 ii 
 
I30 
 
 A Chemical Philosophy. 
 
 (( 
 
 solution-densities which, in his words, "are 
 suggested by the different diffusibi . of 
 salts, and to which alone, guided by the analo- 
 gies of gaseous diffusion, we can refer these 
 diffusibilities. Liquid diffusion thus supplies 
 the densities for a new kind of molecules, but 
 [supplies] nothing more about them." "The 
 fact that the relations in diffusion of different 
 substances refer to equal weights of these sub- 
 stances, and not to their atomic weights or 
 equivalents, is one that reaches to th very 
 bases of molecular chemistry. The Hon 
 
 most frequently perceived is that of equality. 
 In liquid diffusion we appear to deal no longer 
 with chemical equivalents, or the Daltonian 
 atoms, but with masses even more simply 
 related than these in weight. Founding still 
 upon the chemical atoms, we may suppose 
 that they can group themselves together in 
 such numbers as to form new and larger mole- 
 cules, of equal weight for different substances ; 
 or, if not of equal weight, of weights which 
 appear to have a simple relation to each other. 
 It is this new class of molecules which appears 
 to play a part in solubility, and in liquid diffu- 
 
A Historical Retrospect. 
 
 i^ not the ato^s of ehe.ica, Jb' 
 
 The reader can judge how far this generah'za. 
 ;on of Graham, as to an apparent polymeriz-. 
 
 relative rates of aqueous diffusion, led the 
 -mer naturally to the broader doctrine o 
 polymerization alike in liquid and solid specie 
 as put forth by him in ,853, ,„, ^„^^^ .^^^^^ 
 Here, also, .s the view, reiterated by Spence; 
 
 cJesTTh^^''^^^''"""^''''^^^^'-" 
 c« es by th. union of many chemical molecules. 
 
 S 84. Co. -mumg his studies in diffusion 
 
 Graham wrote farther, in ,86,.... So similarTn 
 c aracter to volatility is the diffusive pow 
 
 P sessed by all liquid substances, that we may 
 
 a, csT """" ^ *" "' ^"^"^S"- analyt,- 
 
 cal resources to arise from it " o 
 
 degree of diffusible mobility exhibited^d-ffi 
 nt s b tances appears to be as wide'as t 
 
 UwIsn''" """■"■" °f P°'----' hydrate 
 " "'^ "'^" ^^'^ ">at it has double the velocity 
 
 i 
 
132 
 
 A Chemical Philosophy. 
 
 ft I 
 
 of diffusion of potassium sulphate, and this 
 double that of sugar, alcohol, and magnesium 
 sulphate ; all of which, howc 'er, as regards diffu- 
 sion, he compared to the more volatile bodies — 
 the comparatively fixed, or non-volatile bodies, 
 being represented by the colloids. Of these he 
 remarks that, '* while the rigidity of crystalline 
 structure shuts out external impressions, the 
 softness of the gelatinous colloid partakes of 
 fluidity, and enables the colloid to become a 
 medium for liquid diffusion, like water itself." 
 " Colloids are characterized by mutability." 
 "Their existence is a continual metastasis."^ 
 His conjecture that colloids have perhaps a 
 higher equivalent weight than crystalloids, has 
 apparently no substantial basis. We have 
 elsewhere (§ 30) noticed the earlier observa- 
 tions of Breithaupt on colloids, both of aqueous 
 and igneous origin, called by him porodic bod- 
 ies. The relation of such substances to the 
 process of diffusion was, however, unknown 
 to Breithaupt, and was discovered by Graham. 
 
 ' The papers of Graham above cited, published in the 
 Philosophical Transactions for 1850 and 1861, are reprinted in 
 his Chemical and Physical Researches, 1876, pp. 444-600. 
 
A Historical Retrospect. 133 
 
 § 85. As early as 1847, in a paper already 
 noticed (§ 20), Favre and Silbermann 1 had 
 described the loss and fixation of water in the 
 efflorescence and deliquescence caused by the 
 action of the atmosphere on certain bodies 
 and the precipitation by heat of anhydrous' 
 sodium sulphate from its aqueous solution 
 as alike chemical processes. As facts in the 
 same order, Graham had shown, in 1849, that 
 both liquid and gaseous diffusion may produce 
 chemical decomposition, and had compared 
 these processes to volatilization. It was re 
 served for Henri Sainte-CIaire Deville to take 
 another step in this new way by his studies in 
 chemical dissociation, the publication of which 
 was begun in 1857, when he described the 
 decomposition by heat of potassium hydrate 
 and showed the partial decomposition of water 
 at temperatures much lower than had hitherto 
 been suspected.2 In i860, he said of dissocia- 
 
 n assim- 
 
 tion 
 
 ilating these phenomena to those of the ebulli- 
 .os!-^7'" ''™'"' "= '^^^'- 0" =-■-«. .54;. «iv. 
 
 ^ Ibid., 1857; xlv. 857. 
 
 ^Jll,l 
 
134 
 
 A Chemical Philosophy. 
 
 .»»■■' 
 
 tion of liquids, or the vaporization of non-lique- 
 fiable solids." ^ The action of metallic points 
 in promoting ebullition was then by him com- 
 pared to that of manganese oxyd in fused potas- 
 sium chlorate. 
 
 § ^6. Returning to the subject in 1863,^ 
 in farther discussion of the decomposition 
 of water by heat, Deville wrote : " The com- 
 parisons between the effects of cohesion and 
 of affinity, which are so instructive for liquid 
 and solid bodies, are maintained in the in- 
 verse phenomena of volatilization and de- 
 composition. Admitting this comparison, we 
 see that the phenomena of the decomposition 
 of bodies at a relatively low temperature, or 
 dissociation, corresponds to the vaporization of 
 a liquid at a temperature below its boiling- 
 point ; and that the quantity of the body disso- 
 ciated at a given temperature will be propor- 
 tional to its tension of dissociation expressed 
 in millimetres of mercury ; as the quantity of 
 vapor formed above a liquid at a given tempera- 
 ture is proportional to the maximum tension of 
 
 ^ L., E., and D. Philos. Mag., i860 ; xx. 457. 
 
 2 Comptes Rendus de I'Acad., 1863; Ivi. 195-201. 
 
A Historical Retrospect. 
 
 135 
 
 its vapor." " The phenomenon of the decompo- 
 sition of bodies is in all respects similar to that 
 of the ebullition of liquids, the principal charac- 
 ter of which is the invD "lability of their tem- 
 perature, whatever the intensity of the source 
 of heat, provided the pressure is constant." 
 
 Thus, while looking upon the cohesion of 
 liquids, and their volatilization, as phenomena in 
 some way distinct from those of chemical com- 
 bination and decomposition, Deville was forced 
 to conclude that they are governed by the same 
 la"vv& , involving a change of state and of ther- 
 mic relations, and subordinated to the same 
 conditions of temperature and of pressure. 
 
 § 87. In considering, in 1863, the phenomena 
 of dissociation, as then lately studied by Pdbal 
 for ammonium chlorid, and by Wanklyn and 
 Robinson for sulphuric acid and phosphorus 
 chlorid, Deville recalls the phenomena of diffu- 
 sion, as studied by Graham in aqueous solu- 
 tions, and adds: We have here "a veritable 
 force which leads to the separation of elements, 
 and which must not be neglected in the 
 explanation of the phenomena described by 
 Messrs. P^bal, Wanklyn, and Robinson, since 
 
 iil 
 
136 
 
 A Chemical Philosophy. 
 
 il ! 
 
 the same reasoning applies to aqueous diffu- 
 sion and to diffusion in gases or vapors which 
 have different diffusive powers or rates of 
 transpiration. The new agent of decomposi- 
 tion introduced by Graham is so energetic that 
 we can no longer designate as spontaneous the 
 decompositions produced under its influence." ' 
 
 Still later, in 1865,^ Deville wrote of chemical 
 combination : " We have no knowledge of what 
 combination is ; we do not even know what 
 distinguishes it from solution ; but we can 
 characterize it as a change of state, marked 
 by new physical or chemical properties, serving 
 to distinguish combination from simple mixture. 
 This change of state is most generally accompa- 
 nied by a disengagement of latent heat, which 
 approximates combination to the condensation 
 of vapors ; but it may also be accompanied by 
 an absorption of latent heat, or cooling, as for 
 explosive bodies like NO and NClj, which are 
 formed by combination in the nascent state, 
 and give off heat in decomposing ; so that the 
 
 1 Comptes Rendus de I'Acad., April 20, 1863 ; Ivi. pp. 
 
 729-733- 
 
 2 Bulletin de la Society Chimique; iii. 15. 
 
^ Historical Retrospect. 137 
 
 disengagement of heat, the production of cold, 
 or the absence of thermometric effect, proves 
 nothing for or against the fact of combination." 
 § ^^. Thus we have seen that Favre and 
 Silbermann, in 1847, regarded the separation of 
 salts from solutions by changes of tempera- 
 ture, the fixation of aqueous vapor from the 
 atmosphere by certain bodies, and its loss by 
 others, as all alike chemical changes. Graham, 
 in 1849, insisted upon the likeness of the vola- 
 tilization of liquids to gaseous and liquid diffu- 
 sion, and asserted that all of these processes 
 may produce chemical decompositions. Henri 
 Sainte-CIaire Deville, in 1857 -1863, while 
 adopting Graham's conclusions, farther de- 
 clared that the decomposition of bodies by 
 heat is in all respects similar to that of the 
 evaporation of liquids, and is subordinated to 
 the same laws. 
 
 § 89. The writer, who enjoyed the great advan- 
 tage of personal intercourse alike with Graham 
 and with Sainte-Clairc Deville, and conversed 
 with both of them on the subjects here dis- 
 cussed, had with the latter, whom he had then 
 long known, frequent conferences during the 
 
 Hi 
 
 ii, 
 
i 
 
 138 
 
 A Chemical Philosophy. 
 
 itl 
 
 i-' \ 
 
 spring and summer of 1867, at his laboratory, 
 at the Ecole Normale, in Paris, when the rela- 
 tions of the homogeneous volatilization of liquids 
 and solids were compared with the phenomena 
 of dissociation. Graham, whom I had known 
 since 1856, was there for a few days our com- 
 panion ; and to both of these I maintained, in 
 accordance with the views in my paper, then 
 recently published (10), that the liquid and 
 solid bodies, water and ice, are polymeric spe- 
 cies, distinct from aqueous vapor, their conver- 
 sion into which is a process of depolymerization, 
 or homogeneous disintegration ; a conclusion 
 admitted by both Graham and Deville to be 
 a logical deduction from their own premises, 
 as has already been shown. The views which 
 I have advocated in various publications since 
 1853, and in the preceding chapters, with 
 regard to the constitution of liquids and solids, 
 their high equivalent weights, and all their 
 relations to gases and vapors, appear to be in 
 fact but the legitimate and necessary conse- 
 quences of those first put forward by Favre and 
 Silbermann, and continued by Graham, Deville, 
 and myself. 
 
 < .1 
 
CHAPTER XIII. 
 
 CONCLUSIONS. 
 
 § 90. The views maintained in the preced- 
 mg chapters as a basis for a philosophy of 
 chemistry, may be resumed as follows :_ 
 
 The chemical process may be defined as the 
 integration or the disintegration of chemical 
 spec.es, resulting in the production of new spe 
 ces, also chemical. Both of these chano-es 
 may be either homogeneous or heterogeneous ■ 
 that ,s to say, the species concerned therein 
 may be elementary, or, if complex, may be lilce 
 or unlike in centesimal composition. 
 
 The generation, by heterogeneous change of 
 spec.es dissimilar to the parents we have desig- 
 nated metagenesis. In heterogeneous Integra- 
 t.on two or mo.e unlike species combine to 
 form a new one, and in heterogeneous disinte- 
 grat.on a species separates into two or more 
 unUke to each other. The union of hydrogen 
 and carbon to form acetylene, of oxygen and 
 
 '39 
 
 1 1 
 
140 
 
 A Chemical Philosophy. 
 
 carbon to form carbon dioxyd, the absorption 
 of the latter by sodium hydrate, or of atmos- 
 pheric water by calcium chlorid, are examples 
 of heterogeneous integration. The loss of 
 water in the evaporation of a saline solution, in 
 the efflorescence of hydrated sodium carbonate, 
 and the disengagement of carbon diox3'd by 
 heat from calcium carbonate, are, in like man- 
 ner, examples of heterogeneous disintegration. 
 All solution is heterogeneous integration ; 
 while the separation of crystals from a solu- 
 tion is heterogeneous disintegration. 
 
 What is called double decomposition con- 
 sists in heterogeneous integration, followed 
 immediately by a disintegration generating two 
 (or more) new species. In other words, two 
 species disappear, and two others take their 
 places ; the double decomposition being the 
 result of two consecutive actions, and the hete- 
 rogeneous disintegration following so closely on 
 integration that it is difficult or impossible to 
 arrest the change at the end of the first stage, 
 so as to isolate the unstable species before it is 
 destroyed. When these processes are confined 
 within narrow limits of time and temperature, 
 
Conclusions. 141 
 
 the hitherto unexplained operation has been 
 called catalysis, or action by presence. 
 
 §91- The generation, by homogeneous 
 change, of species like the parents in cen- 
 tesimal composition we have designated met- 
 amorphosis. In homogeneous integration the 
 identity of a species is lost in that of a new 
 one of higher equivalent weight. In homoge- 
 neous disintegration this process is reversed, 
 and a new species is formed, having the same 
 centesimal composition but a lower equivalent 
 weight. These two cases of metamorphosis 
 correspond to what are called polymerization 
 and depolymerization. 
 
 In many instances, as in the vapors of sul- 
 phur at different temperatures, and in pentene, 
 and the various aldehydes and their polymers,' 
 the ratios between the equivalent weights of 
 the species concerned are very simple; but 
 m other cases, as in the polymers of many ele- 
 mental species, such as carbon, tin, and phos- 
 phorus, in silicon dioxyd, and in native silicates 
 and carbonates, these ratios are more complica- 
 ted, and do not correspond to very simple frac 
 tions or multiples. Hence we infer, in the 
 
 tt i. 
 
 i ■ 
 
142 
 
 A Chemical Philosophy. 
 
 sill 
 
 process of metamorphosis, a temporary homo- 
 geneous disintegration of the species into more 
 elemental forms, which, by redintegration, may 
 give rise to new species, either of higher 
 or of lower equivalent weights than the par- 
 ent. 
 
 § 92. Some species with difficulty assume or 
 maintain a polymeric state, — as, for example, 
 carbon dioxyd, which is liquid only at very low 
 temperatures, or under great pressure, and, 
 moreover, forms a very volatile and unstable 
 solid ; while other species, like carbon itself, 
 silicon, and silicon dioxyd, are known to us 
 only in dense polymeric forms, of great though 
 different degrees of condensation. Between 
 these two extremes are bodies which, like 
 phosphorus, pentine, and the aldehydes, yield 
 various polymers of different degrees of com- 
 plexity and of stability. 
 
 All known liquid and solid species, whether 
 elementary or not, are polymers of some simpler 
 species, which, in very many cases, is capable 
 of assuming the form of a gas or vapor. Such 
 vapors themselves are sometimes polymers 
 which, at higher temperatures, may be re- 
 
Conclusions, 
 
 143 
 
 solved into still simpler forms by homogeneous 
 differentiation, as in the case of metaldehyde, 
 of sulphur-vapor below 500°, and of iodine-vapor 
 below 800°. Theoretically, we may suppose 
 that even oxygen, nitrogen, and hydrogen may 
 also undergo such resolutions at higher temper- 
 atures and under diminished pressure. There 
 are, however, many solid species which, from the 
 facility with which they undergo heterogeneous 
 differentiation, or from their high equivalent 
 weights, cannot exist in the vaporous state. 
 
 By integration, alike in metagenesis and 
 metamorphosis, we rise to higher chemical spe- 
 cies, and by disintegration descend to simpler 
 ones. If, as we may suppose, all chemical spe- 
 cies have come from one primal matter, it 
 follows that the final disintegration of all 'so- 
 called elementary species must be a homogene- 
 ous one, giving rise to that primal substance, 
 which can only be conjectured to be a species 
 much more attenuated than hydrogen, and pos- 
 sibly identical with the matter giving the green 
 line 1474 of the corona, or some other unknown 
 solar element. 
 
 § 93. The condensation of gases into solids 
 
144 
 
 A Chemical Philosophy. 
 
 J 
 
 t 
 
 or liquids, and the fusion and volatilization of 
 these, when not attended with heterogeneous 
 disintegration, arc examples of metamorphosis. 
 All such changes of state — the conversion of 
 water into steam, the condensation of this again 
 into water, its conversion into ice, and the fusion 
 and evaporation of the latter — are, conse- 
 quently, chemical processes. The precise na- 
 ture of the liquid and of the colloid or porodic 
 state, as compared with crystalline individual- 
 ized solids, is not yet clear. The passage from 
 the colloid to the crystalline, as well as that from 
 the liquid to the crystalline, is generally at- 
 tended with condensation ; while the fusion of a 
 solid is a metamorphosis by expansion. To this, 
 however, the conduct of water, and some other 
 bodies in solidification, offers an exception. The 
 same vaporous species, steam, gives rise by 
 polymerization to the two distinct species, 
 water and ice, having different equivalent- 
 weights. Analogies to this are s' u j 
 different forms of liquid and •^'' " noi -, 
 and of tin, in the various liqu and .id spe- 
 cies of di-pentines or turpentine-oils '>' ith differ- 
 ent specific gravities and boiling-points, and in 
 
Conclusions. j^c 
 
 the isomeric butylic alcohols, as well as in 
 native silicates and carbonates. It is probable 
 that the so-called isomers of other non-volatile 
 bodies, like the different tartaric acids, are poly- 
 mers similar in their constitution to these. 
 _ By polymerization, or homogeneous Integra- 
 tion, the normal gaseous or volatile species 
 are thus changed into liquids and solids of 
 greater or less degrees of condensation. Of 
 these the denser, other things being equal, are 
 the harder and the more stable or indifferent to 
 chemical changes such as fusion and solution. 
 This relation has been illustrated at length by 
 showing that the hardness and fixity of "native 
 sulphids, oxyds, carbonates, and silicates, and 
 their resistance to the action of solvents, aug- 
 ment with the condensation of the species. 
 
 § 94- All chemical changes are subordinated 
 to measure and weight, as shown in the law of 
 definite proportions alike by volume and by 
 weight. The law of numbers is made evident, 
 not only in multiple proportions, and in met- 
 amorphosis, but in homologous or progres- 
 sive series, which, so far from being ''con- 
 fined to certain hydrocarbonaceous species, are 
 
146 
 
 A Chcviical Philosophy. 
 
 1 ! 
 1 i 
 
 ; '!< 
 
 found throughout all classes of chemical com- 
 pounds. 
 
 In the combination or integration of gases 
 and vapors the volumes uniting are lost in 
 that of the product, there being an identifica- 
 tion of volume. The converse is true in de- 
 composition, or disintegration, which is differ- 
 entiation. The fact that this law of volumes 
 is universal, and applies not only to gases and 
 vapors but to liquids and solids, has been 
 obscured by the false assumption that the vol- 
 ume for solids is a variable and arbitrary quan- 
 tity, conditioned by crystalline form ; so that no 
 constant comparison was possible between the 
 volume of solids and that of gases. Moreover, 
 there have hitherto been two distinct units of 
 comparison, the one for gases, and the other 
 for liquids and solids. The weight of a given 
 volume of a gas or vapor as compared with that 
 of the same volume of hydrogen gas at similar 
 temperature and pressure, — which is its equiv- 
 alent weight, — is, at the same time, its specific 
 gravity, hydrogen being unity. The weight of 
 a similar volume of a liquid or solid species is, 
 on the contrary, compared with that of water ; 
 
 I 
 
Conclusions. „ j.- 
 
 and its equivalent weight varies as its specific 
 gravity, tlut of ^vater, wl,icl, at its maximum 
 density is tl,e unit, being ,628 (H,0) = 29,.44. 
 !>95- In order to compare liquids and solids 
 W'tli gases and vapors, it is necessary to refer 
 them to a common standard of density, or, i„ 
 other wor<ls, to determine the relation of den- 
 s^y between water and hydrogen gas. This is 
 the relation oid:p ,n the proportion d ■./.■■,■„ 
 
 provided ,. be the density of water at 4-; and 
 / that of hydrof en at 0°. To fix this relation 
 we compare the weights of a given volume 
 'one htre) of hydrogen and of steam at 760 mm 
 and ,00", with the same volume of water at the 
 same temperature ; remembering, meanwhile, 
 that this liquid at 4" has a weight of ,000 
 grams to the litre. We have thus the means 
 of determn,ing the specific gravity of hydrogen 
 gas, of steam, and of water at 100°, -the tem 
 perature of its ebullition and its condensation 
 at 760 mm., _ as compared with water at its 
 maxmium density, which has been assumed as 
 the unit of specific gravity for liquids and 
 solids. 
 
 § 96. With gases and vapors, the equivalent 
 
148 
 
 A Chemical Philosophy. 
 
 i,j4^ 
 
 weights of which are directly as their densities, 
 it is evident that in the proportion d : f : \ : v, 
 we have d=^p. But when this formula is ap- 
 plied to liquids and solids, while / still repre- 
 sents alike the equivalent weight and the den- 
 sity (hydrogen being unity) of the normal 
 gaseous ; pecies, d is made to represent the 
 density of some polymer thereof. In the case 
 of water itself, where /= 17.9633, is both the 
 equivalent weight and the density of steam, 
 HoO (hydrogen gas, H2= 2.0000), rt' represents 
 the weight of that liquid at its maximum den- 
 sity (which is assumed as the unit of specific 
 gravity). We have then : — 
 
 1. 0000 : 17.9633 :: i 
 
 I7-9633- 
 
 The number thus found is the reciprocal of 
 the coefHcient of the condensation suffered by 
 p in passing from the gaseous condition to the 
 density in question. To determine the amount 
 of this condensation we have dimply to compare 
 the weight of equal volumes of the gaseous p 
 and the liquid d at the same temperature, or, in 
 other ww.^s, knowing the weight of a litre of 
 steam, HgO, at the standard pressure, and 100°, 
 
Conclusions. 
 
 149 
 
 to compare it with the weight of a litre of water 
 at 1 00°. In this way we have found that water 
 IS formed by the condensation into one volume 
 of 1628 volumes of HoO, and consequently that 
 1628X 17-9633 =29,244 = the equivalent weight 
 of water ; its specific gravity at 100° being 
 0.95878. 
 
 In the proportion d'.pwiw, as applied to 
 any liquid or solid species, / does not represent 
 its real rquivalent weight, but the weight of 
 the normal species which, by its condensation, 
 gives rise to the liquid or solid. The value of v 
 is thus that of the reciprocal of the coefficient 
 of condensation. The equivalent weight of 
 water (and of any other species having a spe- 
 cific gravity of i.ooo) being as given above, 
 we have 29,244 -f- 7- = the coefficient of con- 
 densation. 
 
 From these data, remembering that the law 
 of volumes is universal, and that equivalent 
 weights are but the weights of equal volumes, 
 it is clear that the equivalent weight varies 
 directly as the specific gravity ; so that, this 
 being known, it is easy to calculate the true 
 equivalent weight of any species. 
 
150 
 
 A Chemical Philosophy. 
 
 % 
 
 § 97. The phenomena of temperature, radiant 
 energy, and electricity, ap^ irent in chemical 
 changes, do not belong to chemism, but to 
 dynamics. To the dynamical history of species 
 pertain all questions as to the atomic or molec- 
 ular constitution of matter, on the one hand, or 
 its infinite divisibility, on the other. Contin- 
 ued subdivisions cannot effect the destruction 
 of a chemical species, which is an integer or 
 unit, in which the existence, as such, of none of 
 the species which may be obtained by its disin- 
 tegration can be affirmed. No hypothesis as 
 to an atomic or molecular structure, framed to 
 explain dynamic phenomena in any given spe- 
 cies, can, therefore, be legitimately extended 
 to explain the generation of those species 
 which may be derived from it either by inte- 
 gration or disintegration. For these reasons it 
 is conceived that all such hypotheses, however 
 useful they may be found in the explanation of 
 certain dynamical phenomena, are foreign to 
 the domain < ^ chemistry, and should hold no 
 place in the theory of the science. 
 
 § 98. The chemical process is subordinated 
 to the influences of pressure, temperature, and 
 
Conclusions. 
 
 151 
 
 radiant energy. Pressure influences chemical 
 change, as seen in its relations to vaporization, 
 and to heterogeneous dissociation, as well as 
 to solution and to fusion ; all of which it aids 
 or restrains according as these are attended by 
 condensation or expansion. A remarkable case 
 is seen in its effect on the brittle spec^^s of tin, 
 which, by pressure, undergoes a ready meta- 
 morphosis into the denser species. In like 
 manner, as W. Spring has shown, ordinary 
 phosphorus is, by great pressure, changed into 
 one of the denser red species (§§ 5, 54). Hete- 
 rogeneous integration is moreover directly 
 effected thereby, as in Spring's experiments 
 upon mixtures of metals with sulphur, or with 
 each other. 
 
 Heat promotes union within certain limits, 
 as seen in the solution of many substances in 
 water, and in combustion ; where, however, it 
 may act by first causing dissociation, since 
 nearly all species known are disintegrated at 
 sufficiently high temperatures, when the ten- 
 dency to integration is nullified, and matter 
 becomes indifferent to chemical change. Heat 
 is the universal disintegrator; and chanoe of 
 
152 
 
 A Chemical Philosophy. 
 
 state comes in the primal matter by reduction 
 of temperature, and increase of pressure, with 
 which chemical integration begins. Radiant 
 energy also effects chemical change, as seen in 
 the action of light ; and the electric current 
 causes chemical disintegration, in a way not yet 
 well understood. 
 
 Chemism, however, is not to be confounded 
 with any of the dynamic agencies just mentioned. 
 It is one of the manifestations of an energy per- 
 taining to matter, which inclines it to integra- 
 tion or disintegration, as conditions favor the 
 one or the other mode of change. The energy 
 thus displayed in change of state appears also 
 in these dynamic activities, and is one and the 
 same, whether manifested on the plane of dy- 
 namics, on that of chemism, or on the higher 
 plane of biotics ; but it is an error to confound 
 either dynamical or biotical with chemical 
 activity. 
 
INDEX. 
 
 The black-faced figures in parenthesis — thus, (1) — alike in 
 the Index and in the text, corresi^ond to those prefixed on 
 pages 1-5 to the titles there numbered 1-17, which are printed 
 below in capitals. 
 
 Acetylene, formation of, 139 
 
 Acids, inorganic, complex, 49; fatty, vapor-density of, 122, note 
 
 Action by presence, 14, 141 
 
 Alcohol, butylic, isomers of, 91, 145; vinic, diffusion of, 132 
 
 Aldehyde, acetic, S3; polymers of, S9, 105, 141; formic, 84; 
 
 polymer of, ibid. 
 Allotropism as polymerism, 11 
 Alumina, unit-weight of, 82; density of, 119 
 Amphibole, 47, 57, 58 
 Andrews, Thomas, on vapors, 90 
 Aniline compounds, their equivalent weights, 48 
 Anisomeric homologues, 45 
 
 Anomalies in Atomic Volume, etc. (1), noted, i ; cited, u 
 Aragonite, 53, 93; density of, 105; formula of, ibid. 
 Armstrong and Tilden on turpentine-oils, 87, note 
 Arsenious oxyd, 122, tiote 
 Atmosphere, The Chemical and Geological Relations 
 
 OF (13), noted, 4; cited, 34 
 Atmosphere, part of the interstellar medium, ^^ 
 
 153 
 
 I 
 

 I 
 
 154 
 
 A CJicmical PJiilosophy. 
 
 
 'ft 
 
 Atomic hypothesis, history of, 60 et seq.; Dalton on, 60, 62, 67 ; 
 Brodie on, 67 ; Wright, C. R. A., on, 67, note ; Stallo on, 
 62, note; Whevvell on, 61, note; in chemistry, 62, 65, 66, 
 115, 118, 123, 150; volumes, see Molecular volumes 
 
 Benzoic acid, its solubility, 116 
 
 Bernoulli, kinetic theory of gases, 61 
 
 Biotics definccl, 18, 19; relations of, 21, 152 
 
 Boiling point of liquids, 40 
 
 Breithaupt, A., porodic bodies, 54, note, 132; carbon-spars, 
 
 103 
 Brodie, Benjamin, Calculus, 26, 27; Ideal Chemistry, 29, 31; 
 
 ideal elements, 26, 29, 30 ; atomic hypothesis, 67 
 Bromine, its change by heat, 94, 122, note 
 Butane, its equivalent weight, no 
 Butylic alcohol, isomers, 91, 145 
 
 Cagniard de la Tour on dense vapors, 90 
 
 Calcite, supposed molecular structure, 66; densities, 53, loi, 
 
 \Oi,etseq.; species of, 104; formulas of, 106 
 Camphenes, 80, 96 
 Carbon, chemistry of, 44; series, 44, 49; polymers of, 12,42, 
 
 141, 142; carbon dioxyd, polymers of, 97, 107, 142; 
 
 spars, see Calcite 
 Carbonitcs, the genus, 103 
 Catalysis defined, 14, 141 
 Celestial Ciiemistuv from the Time of Newton (15), 
 
 noted, 4 ; cited, 26-35 
 Changes of state, chemical, 75, 135, 136, 144 
 Charcoal, an anhydrid, 12 
 Chemical activities confounded with dynamics, 19-21, 65, 150, 
 
 152; change related to pressure, 151 ; elements, origin of, 
 
 9, 23 et seq., 37,43, 94; indifference related to equivalent 
 
 weight, 51 et seq., 59, 88, 99, 118 et seq., 145; molecules, 
 
 6},, 114; process, nature of, 7 et seq., 22,80, 139; species, 
 
 integral, 15, 17, 22, 62, 66, 150 
 Chemical Changes, On vwv. Theory of, etc. (4), noted, 2; 
 
 cited, 7-10, 15, 22, 3S-40, 44, 62, 66, 68, 70, Ti 
 
/ 
 
 Index, 
 
 155 
 
 Chemical Classification, On Some rRmcirLEs to be 
 Considered in (2), noted, i; cited, n, 12 
 Remarks on (1). See Anomalies in Atomic Vol- 
 
 UME, lie. 
 
 Chemical Homologies. Illustrations of (6), noted v 
 cited, 47, 106. ^ ^' • ^' 
 
 Chemistry. Celestial, from the Time of Newton (15) 
 ^ee Celestial Chemistry, etc 
 of Primeval Earth ( 1 1 ), noted, 4 ; cited, 26, 28 
 Law of Volumes in (17). noted, 5; cited, 62-64, 78 
 Theoretical, A Century's Progress in (12), notU4; 
 cited 17,22,24-26,31-33 '^' 
 
 rehuion of to dynamics, 20. 21, 65. 152 ; to biotics. ar. 
 
 Chloral, its polymerization, 84 
 
 Chlorids in aqueous solution, 22; as normal species, 119 
 
 Chlorine, its change by heat, 94, ,22, note 
 
 Chlorhydric acid, genesis of. 9; H. Wurtz on its volume, 
 
 Chrysolite, 56, 58 
 
 Clarke, F. W., celestial chemistry, 31, 35 
 
 Clifford, W. K., chemistry and dynamics, 20 
 
 Cobaltic ammonia salts, 48, 79 
 
 Coefficient of condensation, 64, loS, 120, 148 
 
 Cold, action of on tin, 92 ; on iron, 93 
 
 Colloids, their nature, 116, 132; identical with porodic bodies, 
 
 133; their significance in mineralogy, 54; action of fluor- 
 
 hydric acid on, 58, 59 
 
 Colophene, 86-88, 96 
 
 Combination, chemical, Deville on, 136 
 
 Complex inorganic acids of Gibbs, 49 
 
 Condensation, related to hardness, 51, 52 et se<j., 88, 97, nS 
 
 145 ; to chemical indifference, 52, 59,88. 145; in liquid 
 
 species, 40; heat evolved in, 87,88 
 Cooke, J. v., on equivalent weights. 26 
 Corona, the solar, 32, i-], 143 
 Cosmogony, 23, :ioie, 24 
 Cowles's electric furnace, 97, note — - -- 
 
i 
 
 ^1 
 
 156 
 
 A Clicmical Philosophy. 
 
 Crafts, J. M., action of heat on iodine, 94 
 Crookes, W., genesis of elements, 36, yj 
 Cryohyclrates, Guthrie on, 115 
 
 Crystalline individuality, 17, 18, 39; form as related to vol- 
 ume, 71,72 '^^ ■'''"?•' m6 
 Crystallization from solutions, 140 
 Cyanite, 52 
 
 w 
 
 V I 
 
 i 
 
 Hi -J 
 
 Dalton, J., adopts atomic hypothesis, 61, 62, 67, 68 
 
 Datolite, chemical indifference of, 57 
 
 Daubeny, C, the atomic hypothesis, 61, note, 69, note 
 
 Decomposition, double, 9, 13, 14, 98, 140 
 
 Deliquescence, 133 
 
 Density, of solids, relation to equivalent weight, 12, 38, 39, 41, 
 47-49; a function thereof, 118, 120, 149; of water, 
 steam, and hydrogen, 76-78, 147 ; change of, its signifi- 
 cance, 125; variations of in related solids, 102; relation 
 of to temperature, no; law of, loo, 103; units of for 
 gases and solids, 107, 108, -^6 
 
 Depolymerization, 81, 141 
 
 Deville. See Sainte-Claire Deville, H. 
 
 Diethylamine, 115 
 
 Differentiation, chemical, 14, 16, 81, 86 
 
 Diffusion, liquid, Graham on, 75, 129-135; gaseous, 128, 129, 
 136; chemical relations of, 128, 135; applied to chemical 
 analysis, 131 ; compared to volatilization, 128, 131 ; mole- 
 cules of Graham, 130 
 
 Di-pentine, 87 
 
 Dipyre, 53 
 
 Disintegration, chemical, 17, 80 
 
 Disintegrator, heat the universal, 151 
 
 Dissociation, chemical, a universal law, 28 et seq., 35, 94, 151; 
 celestial, 27, 28, 32, 143; compared to vaporization, 
 128, 134-136; Sainte-Claire Deville on, 27, 28, 138 
 et seq. 
 
 Di-turpene, 86 
 
 Dobereiner on chemical triads, 24 
 
 Drion on dense vapors, 90 
 
157 
 
 on 
 
 Index, 
 
 Dumas, J. B., origin of elements, 24-26, 32 et scq., 35; 
 
 atomic volumes, 71, 73; conferences with, 73 
 Dynamics, relation of to chemistry, 19 d seq., 65, 150, 152 
 
 Earth, Chemistry of the Primeval (11). See Chemis- 
 try OK THE Primeval Earth 
 
 Efflorescence, 133 
 
 Electricity, 95, 98, note; in chemical changes, 152 
 
 Elements, chemical. See Chemical elements 
 
 Energy in nature, 21, 152 
 
 Epidote, 56 
 
 Equivalent Volumes, On, etc. (4). See Chemical 
 Changes, On the Theory of; also. Mineral Spe- 
 cies, ETC. 
 
 Equivalent weights, elevated, 47-49, 79, „2; of carbon-spars, 
 47, loi et seq.; of feldspars, 47; of pvroxcnes, ibid.; of 
 water and ice, 78, 109, 149. See Density, etc. 
 
 Euphotide and saussurite, on, 51 
 
 Eutectic bodies, 116 
 
 Eutexia, Guthrie on, 116, note 
 
 Evaporation, related to diffusion, 128, 131, 133, 137; a chemi- 
 cal process, 137, 138, 140, 144 
 
 Faraday on chemistry and dynamics, 20 
 
 Fatty acids, vapor-density of, 122, note 
 
 Favre and Silbermann, thermo-chemistry, 39, 113; chemical 
 
 changes, 133, 137 
 Faye's solar hypothesis, 27 
 Feldspars, 47, 56, 58 
 
 Formulas, structural, in chemistry, 15, 45, (^-j^ note, 97 
 Fouque, fluorhydric acid on silicates, 56 
 Fusibility related to condensation, 119, 145 
 
 Ganot, Elements de Physique, 76 
 
 Garnet, 56 
 
 G-ses, densities of, related to solids, 38, 70, 107, no, 147, 149; 
 
 unit of density for, 107, 146; law of diffusion of, 129; 
 
 Kinetic theory of, 61. See Normal or gaseous species 
 
158 
 
 A Chemical PJiilosophy. 
 
 Gaudin, crystalline molecules, i6 
 
 Gay Lussac, law of volumes, 69 
 
 Gems, order of, 54 
 
 Genealogy, chemical, 9, 15, 97 
 
 Genesis of chemical elements. Sec Chemical elements, origin 
 of 
 
 Gcogeny, 19, note, 23, note 
 
 Gerhardt, Ch., on progressive series, 43; on structural formu- 
 las, 45 
 
 Gibbs, Wolcott, on polytungstates, 48 ; complex inorganic 
 acids, 49 
 
 Gmelin, L., on volumes, 71 ; condensation of oxyds, 88 
 
 Graham, Thomas, on liquid diffusion, 75, 12S, 133; relations 
 of to volatilization, 137; colloids, 132; polymerization 
 in solution, 129-131; conferences with, 13S 
 
 Guthrie, Fred., cryohydrates, 115; physical molecules, 1 1 5-1 18 ; 
 eutexia, iiS 
 
 Gypsum, 98 . , 
 
 V 
 
 ?'5 
 
 Halloysite, 58 
 
 Hardness, its relation to condensation, 51, 52, 88, 97, 118, 
 
 MS 
 
 Heat, its relation to chemical changes, 136, 151; evolved in 
 polymerization, 87 d scq. 
 
 Hegel on chemical change, 16, 17 
 
 Helium, a supposed solar element, 37 
 
 Helmholtz on chemistry and dynamics, 20 
 
 Henry, Louis, on polymerization, 118 d scq. 
 
 Heptine, 86 
 
 Herepath, J., kinetic theory of gases, 62 
 
 Heptine, 86 
 
 Hinrichs, G., on primary matter, t^-}^, note > 
 
 Holoedrites, the genus, 105 
 
 Homogeneous chemical species. Sec Chemical species, inte- 
 gral 
 
 Homologous series, history of, 43, 44, 49, 145 ; their universal- 
 ity, 44, 49, 145 
 
 Homologues, anisomeric, 45; isomeric, ibid. 
 
Index. j-g 
 
 Hornblende, 52, 53 
 Huggins on eloniental matter, ^i, note 
 Hydrofluoric acid, action of on silicates, C6-CQ 
 Hylogeny, 23, note ^ 
 
 Ice. its density, 78 ; relation to water, 91. 144 
 Identification, chemical, 14, 16, 146 
 
 Jollie.'sf "'''""'"■^'^°''' ^^ ^^"-'^ 94, 122, note, 143 
 
 Insolubility related to condensation. ^..Condensation related 
 
 to chemical indifference 
 Integration, chemical, ,7, 139./ ,.5,., ,43, ,3 
 Intcrpenetration in chemistry, 15, 16 
 Iron, supposed effect of cold on, 93 
 Isomorphism, relation to volume, 71-73, 146 
 Isomeric homologues, 45 
 Isoprene, 86, 96 
 
 ]^Zl " """' ™ '^'' ""'"■ ' ■ ""'• 5- 53 
 
 Kant, Em., on chemical union, 15 et sea. 
 
 Kinetic theory of gases, 6i 
 
 Kirchhoff, G., on spectral lines, 37, 95 
 
 Kopp, H., atomic volume, 72; density of water, 77 
 
 Lavoisier on primal matter, 23, 35 
 Leroyer, atomic volumes, 71 
 Leucite, 58 
 
 Light in chemical change, 152 
 Limonenes, 85, 96 
 
 Liquids as polyrners, 41, 48, 143; determination of densities 
 
 or, 40; dmusion in, 1-9-131 
 Lockyer, N., solar physics, 29, 32 
 
 Mackintosh. J. B., action of fluorhydric acid on silicates, 56 
 Macvicar, J. G., on crystalline molecules, 16 
 
 i! 
 
i6o 
 
 A CJicrnical Philosophy. 
 
 II 
 
 ■5||! 
 
 '.i 
 
 •\ ..1 
 
 i 
 
 I; 
 
 Magnesian phosphate, 88, 98 
 
 Materia prima, 17, 23, n, note, 36, 95, 143 
 
 Mathesis, 23, ;/<)/<' 
 
 Matter, divisibility cf, 60 
 
 Meionite, 51, 52, w^te 
 
 Metachlorai, 84 
 
 Metagenesis in chemistry, 8, 15, 45, 80, 97, 139, 143 
 
 Metaturpene, 88 
 
 Metaldchyde, 84, 89, 121, note 
 
 Methylene oxyd, 84, 12 v, note 
 
 Metamorphosis in chemistry, 8, 14, 80 et scq., 141, 142; by ex- 
 pansion, 9, Si ; by condensation, 10, Si 
 
 Metallatcs, 55 
 
 Metallometallates, 55 
 
 Metallic oxyds as polymers, 55, 88, 97, 98, 119, 121, note 
 
 Meyer, Victor, action of heat on chlorine, 99 
 
 Micas, 58 
 
 Micaceous type in mineralogy, 54 
 
 Mills, E. J., genesis of elements, 36 
 
 Mineral Species, On the Constitution and Equiva- 
 lent Volume ok Some (5), noted, 2; cited, 45, 47, 
 62, 70 
 
 Mineralogy, A Natural System of, etc. (16), noted, 5; 
 cited, 55, 57, 64, 65, 79, So, 82, 127 
 
 Mineralogy defined, iS 
 
 Miner/vLogy, OiijKCTS AND METHODS OF (10), noted, 3; 
 cited, i6, 17, 41, 42, 47, 53, 68, 74, 117, 138 
 
 Mitscherlich, isomorphous groups, 72 
 
 Molecular hypothesis. See Atomic hypothesis 
 
 Molecular volume, 63, 65, 124 
 
 Molecules, G3; physical, 63, 114; chemical, 63, 114; diffusion, 
 Graham on, 130 
 
 Mono-pcntme, 88 
 
 Nascen' ?tate of bodies, 98 
 
 Nati iE IN Thought and Language (14), noted, 4; cited, 
 
 14, 18, 19, 20, 21, 2.1, 44 
 N'lbulae, chemistry of, 33-35 ; possible origin of, 2,^ 
 
Index. 
 
 i6i 
 
 Newton, Celestial Chemistry from the Time of (15) 
 
 noted, 4 ; cited, 26-35 
 Newton on atomic hypothesis, 69; his theory of hght, Cn 
 Nitric tetroxvd, 122, note ' 
 
 Normal or gaseous species, 90, 91. 94, 97-99, 107, 119, i=x. note, 
 
 M2, 145, 148, 149 
 Numbers in chemistry, law of, 43 ct scq., 69, 145 
 
 Ocean, part of interstellar medium, ^ 
 
 Oken, Lorcnz, 23; his Physiophilosophy, 23, note 
 
 Umnia mensura et numero, etc., 69, note 
 
 Ontology, 23, note 
 
 Opal, 53, 58 
 
 Osmic oxyd, 121, note 
 
 Otto on atomic volume, 71 
 
 Oxygen, its combining weight, 77, 100, ro2, 108 
 
 Oxyds anhydrous, in mineralogy, 55; solid, as polymers, cc. 
 
 88, 98, 119, 122. note; classification of, 121. note 
 Ozone, II, 93 
 
 Paraldehyde, 83, 84, 89, 122, note 
 
 Pontine, 86 et scq. ■ polymers of, 87, 89-91, 96 
 
 Periodic law, 46 ^ ^ -y 
 
 Petal ite, 56, 58 
 
 Pettenkofer, chemical elements, 24, y 
 
 Phosphorus, polymers of, 12, 42, 91. 126, 141, 142, ici 
 
 1 hylloid type in mineralogy, 54 
 
 PHYsioLor.v, The Domun of, etc. (14). See Nature in 
 
 THOUr.HT AND LANGUAGE 
 
 Physiology, general, 19, note; mineral, ibid. 
 Pickering, Spencer, physical molecules, iij, n; m 
 Pinenes, 85, 96 "^ 
 
 Pneumatogcny, 23, note 
 Polycarbonates, 47, 49, 104-106 
 
 Polymerism defined and illustrated. 10-12, 53, ,,4. ,^5 ; j, ,„ts, 
 39, 40; m non-gaseous species, 41,42, 145; in solids and 
 
■r 
 
 i^ 
 
 162 
 
 A Chemical Philosophy, 
 
 liquids, 48, 142; in water and ice, 40, 75, 76, 82, 91, 108, 
 13S, 144, 147, 148; pentine, 87, 88,89,91,96; aldehydes, 
 83, 84; of butylic alcohol, 91, 145; of various precipi- 
 tates, 98; of oxyds, phosphates, and silicates by heat, 
 88; in solutions, Graham on, 130, 131 ; coefficient of, see 
 Coefficient of condensation ; relation to hardness, see 
 Hardness in relation to condensation ; to chemical in- 
 difference, see Chemical indifference ; to specific gravity 
 of solids, see Density in relation to equivalent weight 
 
 Polymolybdates, 49 
 
 Polyphosphates, 49 
 
 Polysilicates, 47, 49, 118 
 
 Polytungstates, 48, 79 
 
 Polyturpenes, 86 
 
 Polyvanadates, 49 
 
 Porodini of IJreithaupt, 54 
 
 Porodic type in mineralogy, 54, 58, 59, 132; see Colloids 
 
 Pressure, relation to chemical change, 151 
 
 Primal matter. See Materia prima 
 
 Priestley, J., discourse at grave of. See Chemistry, Theo- 
 retical, A Century's Progress in (13) 
 
 Process, The Ciiemical, Thoughts on (7), noted, 3; cited, 
 14, 16, 22; nature of defined, 7-22, 139 
 
 Prout's hypothesis, 25, 46 
 
 Progressive scries in chemistry, 43-45, 48, 145 
 
 Pyrognomic minerals, 88 
 
 Pyroxene, 47, 52, 57 
 
 Quartz, 53, 58, 107 
 
 Reciprocal number, of species, no; of coefficient of conden- 
 sation, 64, loS, no, 14S, 149 
 Rcgnault, V., weight of hydrogen, 76 
 Richards, R. II., metamorphosis of tin, 92 
 
 Ralnte-Claire Devllle, H., on dissociation, 27, 28, 133-136, 
 
 138; conferences with, 137 
 Saussurite. See Euphotide 
 
Index. 
 
 163 
 
 Scheerer, Th, on pyrognomic minerals, 88 
 ^chiel, James, on progressive series, 43 
 
 Sciences, natural, tabular vievv of. 19, „^^, 
 besquiturpenes, 86 " ' 
 
 Shenstone. ^^^ Tilden and Shenstone 
 Silbermann. ^ Favre and Silbermann 
 
 Silicates, tribes of, 57, 58 
 
 Silicon, series of in chemistrv aa ^,^ r 1 
 
 Q7 in, ,'*'>' 44.49; clioxyd,polymerism of, 
 97, 107, 119, 1.2, note, 142; unit-weight for, 82 ; reduc 
 tion and volatility of, 98, note 
 Sillimanite, 52 
 
 Silver nitrate, solubility of, ri6 
 Sodium chlorid, 11. Wurtz on, 126 
 
 Solubility, of oxyd compounds, 99; at high temperatures. it6- 
 
 t geo ogical relations, 1x7; relation of to condensation 
 
 145- •'^'V Chemical indifference, etc 
 
 Solution ano the Chkmical Pkocess. Thoughts on (7). 
 
 noted, 3; cited, 14, 16, 22 '' 
 
 Solution defined as chemical, 22, 1:2. ,4.; as heterogeneous 
 
 integration, 140; densities of Graham, 129 
 Sohds density of as related to gases, 38, 41. 64. 70, 8:. 91, 107. 
 loS, 1:9, 120, r47_,49. unit of density for, 146; as poly- 
 mers, see Tolymerism ^ ^ 
 
 Spar, order of, 54 
 Spathoid type in mineralogy, 54 
 Spathometallates, 55 
 Specific gravity. ^-^-^ Density 
 Spodumene, 56 
 
 Spring, W., chemical effects of pressure, ret 
 btallo on atomic hypothesis, 62, nott 
 Staurolite, 56 
 
 Steam its weight 7fW8, ,09; conversion into water. 75-78. 
 loS, 109, 138-144 » /i /o» 
 
 Stellar matter, chemistry of, 28, 31, 36, 37, 94 
 Stoney, Geo. Johnstone, on solar chemistry, r 
 Stoichiogeny, 23, w/^, 24, 26, 31 
 
1 64 
 
 A Chemical Philosophy. 
 
 I 
 
 Strontian sulphate, g8 
 
 Strii^(.L..al formulas in chemistry, 15, 45, 67, note, 97 
 Sulphur-vapor, density of, 10, 89, 96, 141, 143 
 Sulphur dioxyd, 93, 121, note 
 
 Temperature, relation to chemical change, 150 
 Tetra-pentine, 88 
 
 Tilden. See Armstrong and Tilden 
 Tilden and Shenstone, solution at high temperatures, 116 
 Tin, metamorphoses of, 92, 141, 151 
 Tourmaline, 49, 57 
 Tridymite, 58, 107 
 Tribes in mineralogy, 57 
 Tri-pentine, 87 
 
 Tschermak on crystalline admixtures, 107 
 Turpentine-oils, 85 et seq., 89 
 
 Turpene, its liquid and solid polymers, 85-87, 90, 91 
 Tyndall, J., on potency in matter, 21 
 
 Types in Chemistry, Theory ok (8), noted, 3; cited, 14, 15; 
 their significance, 1 5, 45, 97 ; in mineralogy, 54 
 
 Unit -weights, 79, 82; unit volumes, 79, 83; of density for 
 solids and liquids, 108, 146; for gases, 107, 146 
 
 Valarylene, 86 
 
 Vapors, dense, under pressure, 90; density of as related to 
 solids, see Solids, density of 
 
 Vita! phenomena, 18 
 
 Volatilization, related to diffusion, 131, 137 , compared to de- 
 composition, 134. See Evaporation 
 
 Volumes, Law of in Chemistry (17), noted, 5; cited, 
 62-64, 78 
 
 Volumes, significance of, 71, 79; relation to atomic hypothesis, 
 62, 68; to crystalline form, 71-74, 146; law of, universal, 
 68, 70, 71, 75, 79, 146 
 
 Wallach on turpentine-oils, 87 
 
 Walteishausen, Von, r, ':r"stalline admixtures, 106 
 
Index. 
 
 165 
 
 Water, equivalent weight of, 78, 100; its conversion into steam, 
 75. n^ 78; lieterogeneous dissociation of, 89, 133; its 
 solvent powers at high temperatures, ii6j in flised 
 rocks, 117 
 
 Whewell. W., atomic hypothesis, 61, note 
 Willemite, 58 
 
 Wright, C. R. A., on atomic hypothesis, 67, note 
 Wurtz, Ad., on polysilicates, 118 
 
 Wurtz Henry, geometrical chemistry. 122; on significance of 
 density, 123; his scheme examined, 124-127 
 
 Zircons, varying density of, 53; insolubility of, 56 
 Zoisite compared with meionite, 51, 52 
 

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 Boston.