COBALT. 361 



takes place when this oxide is digested in acids : 

 the excess of oxygen flies off in the state of gas, 

 and the protoxide thus formed unites with the 

 acid. From some experiments of Rothoff, quoted 

 by Berzelius,* it would appear that the oxygen 

 in peroxide of nickel is to that in the protox- 

 ide as 3 to 2. If this be the case, the atomic 

 weight of peroxide of nickel will be 4'75, and it 

 will be a compound of 



1 atom nickel . . 3-25 

 1 atom oxygen . . 1*5 



4-75 



If this supposition be well founded, 47*5 grains 

 of peroxide of nickel, when dissolved in sulphu- 

 ric acid, will lose 5 grains, or 14754 cubic inches 

 of oxygen gas. 



SECT. III. 



OF THE ATOMIC WEIGHT OF COBALT. 



THE sulphate of cobalt, when pure, crystallizes 

 in small red rhombic prisms, very similar to the 

 crystalline form of protosulphate of iron. It 

 may be exposed to an incipient red heat, and 



* Annals of Philosophy, III. 355. 



