Memoir on NkkeL 6f 



scdrcely is it united with the blue oxide of cobalt, cspccicilly 

 if recently precipitated, when it beconies deoxygeaated'j 

 \vhile tlie latter turns black, and is then insoluble in ammo- 

 nia. Before I employed this method of analysis, 1 was de- 

 sirous to ascertain whether it would be attended with the 

 success I expected : I look ten decigrammes of oxide of co- 

 balt, and ten of the oxide of nickel ; and, having dissolved 

 them in nitric acid precipitated by potash, added to it hyper- 

 oxygenated muriate of liiiie, and attenipted their separation 

 by ammonia ; which took place completely. A similar trial 

 which I made on a given mixture of green oxide of iron, 

 oxide of cobalt and nickel, showed me more and more that 

 this method would infallibly succeed. But in the second, 

 as in the first trial, the solution of oxide of nickel having 

 been attended, from the beginning to the end of the process, 

 with a disengagement of bubbles, which I ascribed with 

 justice to the decomposition of the ammonia, and which I 

 supposed to be azotic gas, I was desirous to ascertain the 

 cause of it. The arnmonia could not be decomposed either 

 bv the red oxide of iron, or by the black oxide of cobalt ; 

 neither of them was attacked* On the other hand, I wa.'j 

 certain that the green oxide of nickel dissolved in animonia 

 without being deoxidated. This reasoning led me to admit 

 a hypcroxygenated oxide of nickel, and experience soon 

 proved the existence of this oxide, which had been indicated 

 to me by theory. Its distinguishing characters are, that it 

 dissolves without eServcscence in sulphuric, nitric, and 

 muriatic acids; in the first two, with a disengagement of 

 oxygen 5 in the third, with a disengagement of oxygenated 

 muriatic acid, like hypcroxygenated oxide of cobalt. This 

 hypcroxyirenated oxide of nickel is black; like it, is formed 

 under several different circumstances ; it may be obtained 

 by bringing to a cherrv-red heat green oxide of nickel, or by 

 treating this green oxide bv oxygenated muriatic acid, or by 

 oxviienatcd muriatic acid saturated \Vith lime; and the latter 

 method is preferable. 



Experiment V. 

 As these trials left me no doubt in regard to the certainty 

 of separating nickel exactly from cobalt and iron, I agitated 

 the oxides of them recently precipitated with oxygenated 

 muriatic acid, saturated with lime. In a little lime they all 

 three passed to the muxitnnni of oxygenation. Being theu 

 brouoht into contact witii anmionia, the oxide of nickel 

 w*as the only one dissolved. I decanted the liquor t;y heat : 

 Iiaving then volatilized the ammonia from it. the oxide Ac- 

 \1 -2 ' posited 



