On a Difficulty in Isomorphism. 51 



that I have supposed^Oil of Vitriol to have to Oxymanganic 

 acid, assuming both of these to be Hydrogen acids. 



Regarded as having metals for their bases, the salts 

 themselves would be constituted, as follows — 



Sulphate of Barytes, Ba S 



Manganate of Barytes, Ba Mn 



Oxymanganate of Barytes, . . . Ba Mn^ 



Sulphate of Soda So S^ 



Manganate of Soda, ...*.. So Mn^ 



Oxymanganate of Soda, .... So Mn* 



Remembering the relation of the acids, as just now ex- 

 plained — remembering that in the salts, constituted as this 

 table sets forth. Barium has to Sodium the same relation 

 as Tin, in its proto-compounds, has to Tin, in its per-com- 

 pounds — I cannot, in the view here presented, perceive any 

 difficulty requiring elucidation, nor any obstacle to forbid 

 our admitting, as analogous in constitution, the salts that 

 have called for all this consideration, in consequence of 

 their being alike in form. These, represented as analogous, 

 are as follows — 



Oxymanganate of Barytes, . . . Ba Mn^ 



Waterless Sulphate of Soda, . . . So S^ ^ 



Waterless Seleniate of Soda, . . So Se^ 



Sulphate of Silver, Sv §2 



Seleniate of Silver, Sv Se^ 



(Silver, in all that went before, being represented by Ag, 

 at the usual atomic weight, but here by Sv, at double that 

 weight.) 



Throughout the foregoing observations, I desire to be 

 understood, as regarding the suggested analogy of oxyman- 

 ganate of barytes and the other salts in question, not as 

 a main proof, nor indeed as one of the proofs, of the doc- 

 trine of oxygen-salts having metals for their bases, but only 

 as a refutation of the rival doctrine, that such salts have 

 oxides for their bases. 



E 2 



