HISTORY OP COBALT AND NICKEL. 55 . 



■«uum comports itself hke that of the simple sulphat. 100 

 parts of this salt afford but 27 or 28 per cent, of carbonat. 



Both these sulphats of nickel are transparent, of a fine 

 emerald green, and unalterable in the air. Mr. Proust is of 

 opinion that the sulphat of potash unites with that of nickel in 

 a constant proportion. 



Extraction o/Nickelin the large way. 



Suppose we have an abundant solution of the ore, first Method of ob- 

 calcined, and afterward vitriolized with the residuums of ether. pu "e" g n '° 

 The business is, to separate the nickel from iron, copper, 

 arsenic, bismuth, and cobalt. The iron is at a maximum of 

 oxidation, and in this state has little affinity with acids. It Iran preeipi- 

 may be precipitated then in the state of arseniat, by means G f a by P otash * 

 potash gradually added. Ammonia, or a prussiat, will after- 

 wrad indicate, whether it be entirely thrown down. 



Into the filtered solution let a stream of sulphurated hidrogen Copper, bis- 

 be passed the copper, bis ninth, and all the arsenic, will be ™^e n j c ai r! . su ], 

 precipitated in the state of sulphuret. phuretted 



When the sulphuretted hidrogen no longer occasions any suipnaTof 

 precipitate, the liquor is to be evaporated for crystallization, mckel from that 

 The triple sulphat of nickel and potash, being less soluble than cry^Hizattpn, 

 that. of cobalt, crystallizes first. By repeating the crystalliza- 

 tions the two salts are sepaiated : but the last portions of the 

 salt of nickel will be contaminated with some sulphat of cobalt, and ablution, 

 from which they may be freed by washing in cold water. 



All these crystallizations require a basis of fine silver, if we in silver vessels, 

 would have the operations go on smoothly. 



A salt of nickel is known to be pure, when the precipitate, Test of its 



dissolved in ammonia, quits this solvent, without our finding puu '" 



any cobalt at the end. 



When we precipitate a sulphat of nickel, we must not be Sufficient pot- 

 r i . • i ii . • ' r -ash mustb« 



too sparing ot potash, otherwise we shall be in danger of pre- use d. 



cipitating sulphat with excess of base, which would affect the 



purity of the precipitate. 



Carbonat of Nickel. 



A hundred parts, heated in a retort, five 54 or 55 of green- Oarbonat of 

 c.. - " . , nickel. 



ish 



