W. Gibbs on the Hexatomic compounds of Cobalt. 291 
is obtained from hot solutions in granular crystals. Its solution 
in hot dilute nitric acid deposits abundant crystals of the ni- 
trate, the oxalate being almost completely decompose ul- 
phate and nitrate of xanthocobalt may be readily prepared 
from the oxalate by boiling with a small excess of mercurous 
sulphate or nitrate, adding, in the first case, a little dilute sul- 
phuric, in the last, a little nitric, acid. As the oxalate can be 
precipitated by ammonic oxalate from the crude nitrate, this 
furnishes a cheap and expeditious method of obtaining the pure 
sulphate. 
The formulas of the salts of xanthocobalt at present known 
become in the new notation: 
Chloride, Co,(NH3;);,(NO,)2Cl, 
Bromide, Co,(NH3),9(NO2).Br, 
Iodide, Co,(NH;),o(NO2)o1, 
Nitrate, Co, (NH), .(NO2).(NO3)4 
Nitrite, Co,(NH,),.(NO2)2(NO2),+40H, 
Sulphate, Co, ( *) 10(NO3)2 
H (SU4)2 
Todo-sulphate, Co,(NH,),o(NO,),(80,)1,4+20H, 
Hyper-iodo-sulphate,  Co,(NH ) ,9(NO2)2(80,)1, 
Auro-chloride _ Co,(NH,),9(NOz)2Cl,+2AuCl, + OH, 
Platino-chloride, Co,(NH,),9(NO2)2 Cl, +PtCl, OH, 
Hydrargo-chloride, Co, (NH3) ,)(NO2)2Cl, + 4HgCl, + OH, 
Oxalate, o,(NH,), o(NOz)o( 24 
Chromate, Co,(NH,) ,9(NO,)2(CrO,)2+20H, 
Dichromate Co,(NH,),9(NOz)2(Cr29;) 
Ammngniaeobalt: 1 100, (NH), »(NO,)z} {Cos (NHs),(NOs)s} 
Ferrocyanide, Co,(NH,)19(% O2)2(FeCy,)+60H). 
I have collected them for the purpose of convenience of 
reference and comparison. 
PURPUREOCOBALT. 
instance, Co,(NH,), ,Cl, 
> 
ing from chloride of purpureocobalt only by water of erystal- 
lization. This view has been adopted by some chemists, re- 
Co,(NH,),,. Reserving the discussion for the present, I pro- 
ceed to ue description of the salts which serve to throw hgit 
upon the question. 
