, 
E 
io 
i 
W. Gibbs on the Hexatomic compounds of Cobalt. 287 
Co,(NH,) 19(NO,),(CrO,).4+20H, 
as the following analyses show : 
0°4340 gr. gave 0°3652 gr. CrO, Ba=35°96 per cent CrO,. 
0°3472 gr. gave 0°2900 gr. CrO, Ba=35°70 per cent CrO,. 
0°6954 gr. gave 0°3370 gr. water = 5°38 per cent hydrogen. 
The salt lost only 0°68 per cent water on drying up to 145° C. 
The formula requires 35°84 per cent CrO,, and 5:24 per cent 
hydrogen. It is remarkable that the salt should retain its water 
of crystallization at so high a temperature. The neutral chromate 
of xanthocobalt furnishes the most convenient method of ob- 
taining the chloride and sulphate of xanthocobalt in a state of 
purity. For this purpose the chromate is to be boiled with 
water and a little acetic acid, and a solution of baric chloride 
added until baric chromate is no longer formed. From the 
d 
directly by the action of the red gases upon cobaltic nitrate 
and ammonia may be employed. I am even disposed to con- 
the neutral chromate, it is available as a means of recognizing 
salts of xanthocobalt, and of obtaining them in a state of purity. 
Of this salt 
—53° ie 
0°6570 gr. gave 0°8200 gr. CrO, Ba==53°33 per cent Cr,0, 
0°3974 gr. gave 0:4950 gr. CrO, Ba=53°23 per cent era 
0°4868 gr. gave 0°1830 gr. Cr,0, ==53'40 per cent Cr, 0. 
Iodosulphates.—A solution of potassic iodide gives no precipi- 
xanthocobal 
