314 Oh the Purificaf'mi of Nickel. 



It is not decomposed by water. — The evaporated solution is 

 immediately decomposed by it. 



Solution of oxide of cobalt in ammonia. — Colour deep red : 

 not decomposed by water. Nor h ihc crofioratcd solution 

 decomposed by water, even when so diluted as to be nearly 

 colourless. 



Solution of oxide of nickel in ammonia. — Colour greenish 

 blue: slowly decomposed by water. Evaporated solution — 

 Colour pure green : decomposed immediately by water. 



As silver and copper may be easily obtained from their 

 solutions by well-known methods, the above-related expe- 

 riments are more particularly applicable for the separation 

 i>f cobalt and nickel; especially ..s the properties of their 

 solutions differ very materially. But as the precipitation by 

 water is often incomplete, and ab.vjys inconvenient on ac- 

 count of the quantity necessarily employed, without ex- 

 amining the extent of its eflects in the present instance, I 

 tried other methods to effect the separation of these oxides, 

 and, after some fruitless attempts, found potash answer this 

 purpose extremely well. When a solution of it is added to 

 the ammoniacal solutions of metallic oxides, the effects pro- 

 .duccd arc as follow : 



Solution of oxide of silaer in ammonia. — Slowly decom- 

 posed, requiring three or four da\s for its completion. The 

 precipitate is blackish brown. I have not examined whether 

 It is fulminating. Evaporated solution — Innnediately de- 

 composed : the precipitate is of a lighter brown than the 

 former. 



Solution of oxide of copper in ammonixi.-~S\o\^'\)' decom- 

 posed, and in very small quantity. Evaporated solution — 

 Ouickly decomposed. 



Solution of oxide of cobalt in ammonia. — Very slowly and 

 sparingly decomposed, even bv large (juantitics of the soki- 

 .tion of potash, and more slowly as the solution is more di- 

 lute. Evaporuled solution, by the addition of potash, gra- 

 dually changes from red to pink ; then becomes scarlet, at 

 length turns brown, and deposits brown oxide of cobalt. If 

 a quantity of solution of potash be added to a small quantity 

 of the evaporated solution, precipitation ensues in a few 

 hours ; but if a considerable quantity of water be added to 

 similar (juantities of the evaporated solution, and of potash, 

 five or six days are required to complete the precipitation, 



Solution of oxide cf nickel in «7/i//io/ji<<.—Iinniedjately de- 

 composed, and the more readily as it is more diluted. Em- 

 poraind iolutivn — The same properties in a greater degree. 



By 



