AMMONIA-COBALT BASES. 33 



The advantage of simplicity is evidently in favor of the formula we have 

 adopted. We may also consider it as represented by 



5NH 3 .Co 2 3 ,2S0 3 -r-2C 2 3 ,HO+HO. 



In this case the salt should have a strongly acid taste which it has not. On the 

 whole the formula 



5NH 3 .Co 2 3 j;^ + 3HO 



appears to deserve the preference. 



NEUTRAL OXALO-SULPHATE OP PURPUREOCOBALT. 



When ammonia is added to a solution of the acid oxalo-sulphate just described, 

 a fine violet-red color is produced, and if no more ammonia be added than is suffi- 

 cient to completely neutralize the acid reaction, the liquid jdelds, on evaporation, 

 beautiful red prismatic crystals of a neutral salt. The neutral oxalo-sulphate is 

 much less soluble in water than the acid salt, and has a purely saline taste: it is 

 easily decomposed by boiling. The formation of this salt is represented by the 

 equation 



.5NH 3 .Co 2 3 ,2S0 3 ,2C 2 3 +2NH 4 0=5NH 3 .Co 2 3 ,S0 3 ,C 2 3 +NHAS0 3 +NH 4 0,C 2 3 . 



The fact that the ammonia unites with both sulphuric and oxalic acid, and not 

 simply with two equivalents of oxalic acid, throws much light on the constitution 

 of the acid oxalo-sulphate, and shows, we think, clearly that the formula of this 

 salt cannot be 



5NH 3 .Co 2 3 ,2S0 3 + 2C 2 3 ,HO 4- HO. 



The constitution of the neutral oxalo-sulphate is represented by the formula 

 5NH 3 .Co 2 3 ,|^+7HO 



as appears from the following analyses : 



0.636T grs. gave 0.3217 grs. sulphate of cobalt = 19.23 per cent, cobalt. 

 0.6721 grs» gave 0.2569 grs. sulphate of baryta = 13.12 per cent, sulphuric acid. 

 0.9760 grs. gave 191 c. c. nitrogen at 17°.25 C. and 767 mm .58 (at 17°.8) = 177.43 c. c. at 0° 

 and 760 mm = 22.83 per cent. 



The formula requires 





Eqs. 



Calculated. 



Found. 



Cobalt 



. 2 



19.21 



19.23 



Sulphuric acid 



. 1 



13.02 



13.12 



Oxalic acid 



. 1 



11.72 





Nitrogen 



. 5 



22.80 



22.83 



We may further remark that the character of the action of ammonia upon the 

 acid oxalo-sulphate leads us to hope that the neutral sulphate of Purpureocobalt 

 may be obtained by the action of this agent upon the acid sulphate, and that in 

 fact, this is the salt already mentioned as so obtained, but not yet analyzed. The 

 two oxalo-sulphates described constitute, we believe, the types of an entirely new 

 5 



