256 W. Gibbs and F. A. Genth 
There can be no reasonable doubt that this salt is isomorphous | 
with the corresponding cobalt salt. Like the latter it is an ex- ) 
tremely valuable test for the salts of Roseocobalt and for certain 
salts of Purpureocobalt. 
OXYD OF ROSEOCOBALT. 
brown oxyd obtained by boiling a solution of sulphate of Roseo- 
cobalt, and afterward washing and drying the precipitate in the 
air, has the formula 
Co3;04+8HO 
as the following analyses show: 
I. 0:4430 grs. gave 0°6990 grs, sulphate of cobalt = 60°05 per cent of cobalt. 
II. 09269 grs. gave 01672 grs. sen (ignited with dactuia ht lead) = 18°08 
per cent. 
Ill. 0°7150 grs. ignited in hydrogen gas gave 0°3010 grs. water, which in connec 
: tion with the 2nd analysis gives 21:88 per cent oxygen in the oxyd of cobalt. 
The formula requires - 
Eqs. Calculated. Found. 
ee es.) ae 88°5 60-00 ee 
Mt a rier | 320 21-69 21° 
+... 9 Gena 270 18°30 18-03 
1475 100-00 99°46 
Frémy’s formula requires 64 per cent of cobalt. Claudet gives 
also the formula Co:30.+8HO i robable, but without analyses. 
On the other hand, it is possible that the different salts, not only 
