ee en 
W. Gibbs on the Hexatom‘e compounds of Cobalt. 119 
possess some value as means of investigation from their remark- 
able power of crystallization. 
Sulphate.—Of all the salts of this series the sulphate is that 
the salt is but slightly soluble; but dilute sulphuric acid dis- 
solves it more readily and without decomposition if the boil- 
ing be not continued too long. Stronger acid readily decom- 
with dilute chlorhydric acid, the solution gradually becomes 
violet-red, and on cooling deposits crystals of chloride of Pur- 
pureocobalt. Of these crystals, 
0°2825 gr. gave 01749 gr. CoOSO,=23°56 pr. ct. cobalt. 
The formula Co,(NH,), ,Cl, requires 23°55 pr. ct. 
he decomposition is accompanied by effervescence from 
the escape of gas, apparently nitrogen mixed with a smaller 
quantity of nitrous acid vapors, and may perhaps be expressed 
by the equation 
2Co, (NH,),(NO,),80,=Co (NHL), Cly-+20080, + 20H + 
ONO, +I2N. 
In this reaction we pass from a lower to a higher ammonia-base, 
and Genth and I have shown that we may also pass from Fur- 
pureocobalt’ to Luteocobalt, or from the decamin to the dode- 
06142 gr. gave 0°3596 gr. CoSO,=22°28 pr. ct. cobalt. 
a ae : 
ee 
“  hydr 
15547 gr. gave 0°6785 gr. BaSO,=17'98 
: = 46 ydrogen. 
04693 gr. gave 123°5 c. ¢. nitrogen at 975 ©. and 754-5"==31°38 
per cent. 
