1839.] 



On Chemical Tests. 



311 



which turns nickel apple green, bat copper blue; and the second 

 produces no immediate precipitate with nickel, but with copper it does. 

 The hydra ted blue oxide of copper is converged to black by boiling. 



b. The greater number of the salts of copper are soluble in water, 

 and speedi'y acquire a blue or green colour on exposure to the air. The 

 salts of sub-oxide of copper are never blue or green, but white, red, 

 brown or black. 



c. The deutoxide of copper is black: it fuses on exposure to a very 

 Strong heat. It readily dissolves in acids. The solution has generally 

 a blue colour. The muriate solution is of an emerald green colour. 



d. The solutions of neutral salts of deutoxide of copper redden lit- 

 mus paper. 



e. Before the blow-pipe with soda on charcoal the salts of copper are 

 reduced to a metallic globule. With borax they give a dark green in 

 the exterior, and a reddish brown colour in the interior flame. 



/. Copper in solution may he decisively distinguished by the joint ac- 

 tion of ammonia and clean iron. Clean iron dipped into and remaining 

 a feiv minutes even in a weak solution of copper, becomes coated with it, 



g. Persalts of copper have a blue or green colour, prosalts are colour- 

 less, but absorb oxygen rapidly and become blue. 



S2. COPPER, metallic detects and precipitates silver in solution. 

 The solution should be somewhat acid in order to precipitate the silver 

 completely. 



a. The following analysis may be introduced here to point out the 

 method of separating copper, from nickel and zinc. See also 41, a. 



b. 24-f grains of copper, 12 grains of zinc, and 20 grains of oxide of 

 nickel were dissolved in nitromuriatic acid. The solution, strongly 

 acidified with muriatic acid, was diluted with about a pint of water; 

 acunentof sulphuretted hydrogen gas was then passed through the 

 solution until all the copper was precipitated; the bisulphuret of cop- 

 per thus formed, having been well washed, was acted on by nitric acid, 

 which dissolved the copper and left some sulphur; after the separation 

 of the latter, the solution of copper was boiled with caustic soda to 

 precipitate the peroxide, which alter ignition weighed 80.4 grains 

 which is equal to 24.3 grains of copper. The solution containing the 

 zinc and nickel was carefully evaporated to dryness to expel the excess 

 of acid, and the residue dissolved in water acidulated with one fluid 

 ounce of strong aceiic acid S. G. l.OtiU and warmed to assist the action. 

 When this was, effected, the solution was diluted to about a pint, and a 

 stream of sulphuretted hydrogen was passed tlnough it until the gas 

 was in excess. A dingy white precipitate of sulphuret of zinc fell 

 which weighed 18 grains, equal to 12 grains of metallic zinc. The 



