Ne ee es TRS 
W. Gibbs on the Hexatomic compounds of Cobalt. 117 
of the containing vessel, while a green flaky matter is at the 
same time deposited. When large quantities of material are 
operated upon, the complete oxidation requires several days. 
On filtering, a bright green mass mixed with orange-yellow 
crystals remains upon the filter; the filtrate is olive-green, and 
on standing often deposits small brilliant orange-yellow scales. 
the mass on the filter is treated with hot, very dilute, sul- 
phurie acid, it instantly becomes bright orange and on boiling 
dissolves. The solution then deposits on cooling a splendid 
salt, which has the formula 
Co,(NH;),(NO2),50, 
and which is the sulphate corresponding to the nitrate already 
mentioned. 
Xanthocobalt, while the prismatic crystals are the nitrate of 
the octamin series above mentioned. In one experiment: 
0°3833 gr. gave 0°1890 gr. CoSO, = 18°77 pr. ct. cobalt. 
The formula of nitrate of Xanthocobalt, Co,(NH,), (NO). 
(NO,),, requires 18°73 pr. ct. 
0°7369 gr. gave 0°4050 gr. CoSO, = 20°92 pr. ct. cobalt. 
The formula of the nitrate of the new series, Co,(NH;,) 
8(NO,)4(NO,),, requires 20°99 pr. ct. Ae idin 
For greater certainty I made also a nitrogen determination in 
this nitrate: 
05668 gr. gave 168°5 cc. nitrogen at 13°°5 C and 756-1™ = 
34°79 pr. ct. nitrogen. : 
The formula cited requires 34°88 pr. ct. The two salts were 
further readily recognized by their characteristic reactions. In 
mY experiments the proportion of Xanthocobalt salt found 
Was much the greater. The formation of the new nitrate may 
' this case be represented by the equation 
2Uo(NO,),+-8NH, +4KNO,-+-OH, + 0=00,(NH,)3(NO2) 
4(NO,).-+2KNO,4+20KH. 
