on the Ammonia-cobalt Bases. 333 
formed, but only a solution of sulphate of Roseocobalt in am- 
monia, from which, by evaporation, the sulphate crystallizes un- 
ed in large dark-red erystals, frequently of the form rep- 
resented in fig. 3. We are unable to assign a satisfactory reason 
for the capriciousness of the behavior of the red sulphate towards 
ammonia, 
Frémy asserts that sulphuric acid, cautiously added to a 
completely oxydized ammoniacal solution of sulphate of cobalt, 
throws down an acid sulphate of Roseocobalt to which he assigns 
the formula 5NHs.Co20s, 580s+5HO. When this acid sul- 
| phate is boiled for a few minutes with ammonia, a yellow precip- 
; itate of sulphate of Luteocobalt is thrown down. The author 
quence of imperfect washing. 
tely throw hich is easily purified, as above, by 
spate ofan Seetptit 4 ssTigatiott. f he acid mother liquor 
_ Sometimes deposits more sulphate on cooling. The supernatant 
