1866.] HUNT— OBJECTS OP MINERALOGY. 113 



state, the chemical formula of the latter being some multiple of 

 the first, and the liquid and solid species themselves often 

 constituting two distinct species of different equivalent weights. 

 In the case of analogous volatile compounds, as the hydrocarbons 

 and their derivatives, the equivalent weights of the liquid or 

 solid species approximate to a constant quantity, so that the 

 densities of these species, in the case of homologous or related 

 alcohols, acids, ethers and glycerids, are subject to no great varia- 

 tion. These non-gaseous species are generated by the chemical 

 union, or identification, of a number of volumes or equivalents 

 of the gaseous species, which varies inversely with the density 

 of these species. It follows from this, that the equivalent weights 

 of the liquid and solid alcohols and fats must be so high as to 

 be a common measure of the vapor-equivalents of all the bodies 

 belonging to these series. The empirical formula, C m H no Oi 2 , 

 which is the lowest one representing the tristearic glycerid, ordi- 

 nary stearine, is probably far from representing the true equi- 

 valent weight of this fat in the liquid or solid state; and if it should 

 hereafter be found that its density corresponds to six times the 

 above formula, it would follow that liquid acetic acid, whose 

 density differs but slightly from that of fused stearine, must have 

 a formula, and an equivalent weight about one hundred times 

 that which we deduce from the density of acetic acid vapor, 

 C 4 H,0 4 . 



Starting from these high equivalent weights of liquid and 

 solid hydrocarbonaceous species, and their correspondingly com- 

 plex formulas, we become prepared to admit that other orders 

 of mineral species, such as oxyds, silicates, carbonates, and sul- 

 phids, have formulas and equivalent weights corresponding to 

 their still higher densities ; and we proceed to apply to these bo- 

 dies the laws of substitution, homology, and polymerism, which 

 have so long been recognized in the chemical study of the mem- 

 bers of the hydrocarbon series. The formulas thus deduced 

 for the native silicates and carbon-spars, show that these poly- 

 basic salts may contain many atoms of different bases, and their 

 frequently complex and varying constitution is thus rendered 

 intelligible. In the application of the principle of chemical ho- 

 mology, we find ready and natural explanations of those vari- 

 ations, within certain limits, occasionally met with in the compo- 

 sition of certain crystalline silicates, sulphids, etc., from which 

 some have conjectured the existence of a deviation from the law 



Yol III. H No. 2 



