On a Difficulty in Isomorphism. 49 



cording to the new view, the anomaly of one class of oxides 

 combining according to a rule different from other oxides, 

 and from other bodies, disappears ; for, according to this 

 view, when Oil of Vitriol, regarded as an Hydrogen acid 



(H2 S), acts on an oxide, it is not a simple combination 

 that takes place, but a double decomposition, resulting in 

 a neutral salt and water, precisely as takes place when 

 Hydro-chloric acid acts on oxides. While, therefore, on 

 regarding Oxygen salts as having metals for their bases 

 instead of oxides, the anomalous aspect of such of them as 

 are formed from oxides of high degrees of oxidation disap- 

 pears, we do not need, in taking this view, to seek any new 

 supposition to stand upon. Nor can it escape your obser- 

 vation, that, regarded in this view, all the oxygen is in a 

 state of unity ; whereas the former view presented it broken 

 asunder, like a sphere, into two irregular parts, which, 

 when examined apart, seemed neither of them symmetrical, 

 but which, being joined again, conceal all that before ap- 

 peared irregular, attesting at once the violence that had 

 rent them asunder and the unity of the artist's design. 



Such unity of all the oxygen in any neutral salt, is re- 

 markably confirmed by the action of the two Sulphates of 

 Mercury on common Salt, in producing by sublimation, 

 Corrosive Sublimate and Calomel. The following diagrams 

 indicate the actions — 



r2Cl ^2HgCl Calo- 



Common salt, . . . . Na C\-\ / mel. 



L Na\ 



v. r2Hg' 



Proto-sulphate of mercury, Hg^S •< ^ \ 



I ^ • NaS Sulphate 



of Soda. 



VOL. IV. 



