W. Gibbs on the Hexatomic compounds of Cobalt. 128 
Dichromate.—This salt is easily formed by adding a solution 
of potassic dichromate to one of the octamin nitrate. It 
separates after a few minutes in beautiful orange-yellow needles 
which may be redissolved and again crystallized without decom- 
osition. In appearance and solubility it can hardly be dis- 
tinguished from the corresponding salt of Xanthocobalt, 
Co,(NH;),,(NO2)2(Cr20,) 2 + 20H. 
The formula of this salt is 
Co,(NH,),(NO2)2Cr20;. 
05604 gr. gave 0°4315-gr. BaCrO, = 32°91 per cent Cr,0,. 
The formula requires 88°06 per cent. The determination of 
and ini 
NO,, can be effected more accurately by means of a baric salt 
Subtracting 23-26 per cent platinum from this we have 13°78 
per cent cobalt. 
Calculated. Found. 
Cobalt « 2 18°91 13°78 
Chlorine 6 25°12 25°04 
Platinum 1 23°23 23°26 
The formula of this salt is therefore 
Co,(NH,),(NOz),Clo + PtCh. 
Auro-chioride.—A solution of auro-chloride of sodium, AuCl, 
Na, produces immediately in one of the octamin nitrate a beau- 
Cold water. For analysis the salt was dried on bibulous paper, 
and afterward in pleno over sulphuric acid. The analysis was 
