On a Difficulty in Isomorphism. 441 



implied that the received atomic weights of sodium and sil- 

 ver must be doubled), then a point is established incon- 

 sistent with the older opinion respecting the constitution 

 of the oxygen salts and oxygen acids ; so that, precluded 

 from that opinion, chemists, in reference to the newer 

 opinion, may be in the situation of travellers, who, finding 

 an old road shut-up, are compelled to proceed on the new 

 made road that lies before them, consoling themselves as 

 they go, by considering how soon usage will give it smooth- 

 ness. 



The suggested analogy between the oxymanganate of 

 barytes and the two sulphates already named, is in part 

 consistent with the usual conception of oxygen salts and 

 oxygen acids, and in part inconsistent. So long as we only 

 compare the salts of soda among themselves, or the salts 

 of barytes among themselves, or even when we compare 

 such of the salts of barytes and soda as are produced from 

 the same acid, no discrepancy arises, as the following for- 

 mulas will make apparent : 



.' The sulphate . ' . .Ba S 

 Of barytes . . . •< The manganate . Ba Mn 



^The oxymanganate Ba Mn Mn 



,' The sulphate . . So S 2 

 Of soda .... <! The manganate . . So Mn 2 



[^The oxymanganate So (Mn Mn) 2 



The sulphate of . \ Bar y tes ■ • • • B * S 

 (.Soda So S 2 



The manganate of | Bar Jtes . . . . Ba Mn 

 (.Soda So Mn 2 



The oxymanganate of j Bar >' tes • • • • Ba Mn Mn 



(.Soda So (Mn Mn) 2 



Here, in consequence of the atomic weight of sodium 

 being doubled, soda becomes a binoxide (So), corresponding 

 with the peroxide of tin (Sn), while barytes remains a 

 protoxide (Ba), corresponding with the protoxide of tin 



