86 THOMAS STEREY HUNT ON A NATURAL SYSTEM IN 



§ 119. The researches of Gibbs iu these complex inorgauic acids, resuming-, extending, 

 and generalizing those of other laborers in the same field, are of much significance to the 

 chemist in his study of natural mineral species, both by establishing the doctrine of a 

 great complexité" of molecule in similar bodies, and by showing the influence of very 

 small portions of some one constituent iu a compoiind. Thus the addition to twelve 

 molecules, or 2*784 parts of tuugstic oxyd, of one molecule or sixty parts of silica, determines 

 the formation of an octobasic silicotungstate, which differs notably in its chemical rela- 

 tions from the corresponding decabasic metatungstate, equally with twelve molecules of 

 tuugstic oxyd. In like manner, the addition to twenty-four molecules of tungstic oxyd of 

 one of phosphoric oxyd gives rise to a new and distinct complex acid ; while small pro- 

 portions of very various oxyds produce other new and well defined compounds. By an 

 analogy not too remote, we are helped to irnderstand the part played in many natural 

 silicates by small portions of fluorine, of chlorine, of sulphur, of siilphates and carbonates, 

 and even of phosphates, arsenates and vanadates, which have hitherto been iu many 

 cases regarded as accidental impurities. 



§ 120. The readers of the second part of this essay will recall that iu putting forth in 

 1853, the views ever since maintained with regard to the condensation of the molecule, 

 and the very complex structure of so-called inorganic compounds, it was affirmed that 

 these views w^onld not only " lead to a correct mineralogical system," but would " be 

 found to enlarge and simplify the plan of chemical science." This latter result it was 

 then farther shown, was to be attained by establishing, for mineral or inorganic species, 

 complex formulas and high molecular weights, and by applying " to these bodies the laws 

 of substitution, homology and polymerism M^hich have long been recognized in the chemi- 

 cal study of the hydrocarbon series." A generation has jiassed since then, and chemists 

 are now, by the methods then first indicated, advancing in this direction towards what 

 Roscoe calls " the establishment of a systematic inorganic chemistry which needs not 

 fear comparison with the order which reigns in the organic branch of our science." He 

 adds, " it is well to be reminded that complexity of constitution is not the sole prerogative of 

 the carbon compounds, and that before this systematization of inorganic chemistry can be 

 effected we shall have to come to terms with many compounds concerning whose compo- 

 sition we are at present wholly in ignorance," and by way of illustration refers to the 

 complex inorganic acids of Gribbs.' 



§ 121. Recognizing from the beginning of this inquiry that the molecular weights of 

 mineral species, while far exceeding those of hydrocarbonaceous or so-called organic 

 liquids and solids, are equally unknown, we have sought, nevertheless, to show the 

 comparative condensation in different mineral species, and at the same time the existence 

 of homologous series among them, by the use of atomic formulas. In these the results of 

 chemical analysis are reduced to their simplest term, and an» presented independent of all 

 hypotheses as to the structure or the molecular weight of the species. These formulas 

 suggest to the chemist something more than the elemental atoms represented by the 

 symbols employed. While he admits in the simplest mineral silicate or oxyd the existence 

 of oxygen, silicon or one or more metals, all being chemical elements physically dissimilar 



' Sir H. E. Ro-scoo, Address to ttie Chemical Section of the Britisli As.soo. Ailv. Pcieiice, Montreal, Aug., 1884, 

 l.'oporl, !.. GG3. 



