OF ARTS AND SCIENCES. 21 



Basic Oxalo-sulphate. — This salt, which in the first part of this 

 paper was assigned to the purpureocobalt series, belongs, as I think, 

 more probably with the salts of roseocobalt, being formed directly 

 from the sulphate of that base. This view compels us to admit the 

 existence of a basic series of roseo-salts, to which, however, I can see 

 no reasonable objection. The formula of the oxalo-sulphate may now 

 be written, 



Co,(NH3),„.0.(aOJ.(SOJ+70H,. 



Acid Oxalo-sulphate. — The acid oxalo-sulphate, described in the 

 same paper, may be written, 



Co,(NH3),„(C,0,),(SA)+30H„ 



and would then be a dioxalo-disulphate. Its structural formula upon 

 this view would be 



O 



Co, 



NH3-NH3- 0-^^202 



nh;-nh3-nh3 Q 

 nh;-nh3-o (.Q 



This formula agrees satisfactorily with the results of the analyses, and 

 with the fact that tlie acid reaction is not very strong. On the otlier 

 hand, it is at least possible that the salt may contain two atoms less of 

 hydrogen. In this case the formula would be 



Co,(NH3),,(C A) (SO,),+C,H A+20H,. 



If the first view be adopted, the formation of the salt by boiling nor- 

 mal sulphate of roseocobalt with oxalic acid may be expressed by the 

 equation : — 



Co,(NH3),„(SO,)3+3CJI,0, = \ Co,(NH3),„(C,OJ,(S,0,)+ 

 C,H,OJ+OH,+SO,H,. 



Upon the second view we should have : — 



Co,(NH3),„(SO,)3+3aH A = \ Co3(NH3),,(C A) (S0,),+ 

 C,H20,^+20H,+SO,H,. 



The second view appears to me preferable, since we have no inde- 

 pendent evidence to show that ordinary sulphates ever lose water to 

 form disulphates, except by the action of heat. 



Oxalates. — Gentli and I have shown that the neutral oxalate of 

 roseocobalt has the formula Co2(NH3)jo(C,Oj3-|-OH2. I find now 

 that, as already stated, this salt is sometimes formed as one of the 

 products of the action of ammonic oxalate upon chloride of puz'pureo- 



