118 W. Gibbs on the Hexatomie compounds of Cobalt. 
and the formation of the nitrate of Xanthocobalt by the equa- 
tion : 
2Co(NO;),4+-10NH,+2KNO0,+0H,+0=0o,(NH,),,(NOz)s 
(NO,),+20KH. 
varied the above process by adding ammonia first to the solu- 
tion of cobaltic nitrate, and afterward the solution of potassic 
nitrite, but the results were the same. 
4, Action of ammonia and potassic nitrite upon a mixture of 
cobaltic and ammonic sulphates.—In this case as in the others 
the solution becomes brown and deposits an orange crystalline 
mass. the mass is dissolved in water and a solution of 
potassic bromide is added, after standing, fine crystals are 
formed, which after a single recrystallization are pure bromide 
of Xanthocobalt. In one experiment: 
0°5634 gr. gave 0°2496 gr. CoSO, = 16°87 pr. ct. cobalt. 
0°7294 gr. gave 0°4496 gr. silver = 45°65 pr. ct. bromine. 
The formula, Co,(NH,), (NO,),Br,, requires cobalt 16°86; 
5°71. I did 
e. 
sent at all its relative quantity must have been small. The 
formation of sulphate of Xanthocobalt is easily explained by 
the equation : 
2.CoSO, +10NH, +2KNO, +OH, +0=Co,(NH,),,(NO2) 
2(SO,). +20KH. 
in wat of the sulphate of the octamin series. 
