56 



Hidrat. 



In thi* state in 

 all its salts. 



HISTORY OF COBALT AND NICKEL. 



ish gray oxide at a minimum. When heated in contact with 

 the air, the oxide is black. 



The minimum oxide is converted into carbonat by exposure 

 to the air. 



Hidrat of Nickel. 



All the salts of nickel, thrown into a boiling solution of 

 potash, are converted into a green hidrat. Boiling does not 

 alter its colour. Potash does not dissolve cither the hidrat or- 

 oxide of nickel. 



The hidrat is reduced to gray oxide by heating. 



In the saline combinations the oxide is in the state of hi- 

 drat. Alkalis precipitate it in this state. 



©xide at a 

 maximum. 



Black. 



Oxigen expel- 

 led by ammo- 



Oxides re- 

 duced. 



Sulphuret. 



Maximum oxide of Nickel. 



The carbonat and hidrat are both oxided to a maximum by 

 the action of oxigenized muriatic acid. The gray oxide is 

 more difficult to oxide. 



The dry oxide of nickel at a maximum is black. When 

 solid its fracture is vitreous. 



This oxide kept in ammonia gives out bubbles, returns to 

 the state of gray oxide, and dissolves in the alkali. 



With muriatic acid at 15° it yields a considerable quantity 

 of oxigenized acid. The solution is greenish yellow, and crys- 

 tals form in it by cooling, 



The oxides of nickel are reduced like that of cobalt. The 

 metal is obtained pretty easily in a button, in which it differs 

 from cobalt, this affording only large grains, 



This metal appears to have taken up a surcharge of sulphur 

 of 46 per cent. ; but Mr. Proust entertains some doubt of the 

 accuracy of this proportion. 



Arscnit and Arseniat. 



Ar^enit. These are made like those of cobalt, and are of a fine apple- 



green colour. 



The arsenit, heated in a tube, loses its colour with its water, 

 gives out white oxide, and changes to an olive green. To ah* 

 strac l>all the arsenic the contact of charcoal is requisite. 



Heated 



