114 Notice of some Recent [Feb. 



colour is removed and a red tint appears. The mass is then 

 washed, and boiled with muriatic acid till all the nitric acid 

 is driven off, and the selenium is then precipitated by sul- 

 phate of ammonia. From 1 to If per cent, of selenium is 

 thus obtained from the residue. 



Precipitation of Antimony by Sulphuretted Hydrogen, {Ann. 

 de Pogg. xxviii. 481.) When antimony is precipitated from 

 the solution of its chloride, in water mixed with tartaric 

 acid, by sulphuretted hydrogen, it is in the state of a pure 

 sulphuret, and retains no sensible quantity of chlorine. But 

 when the gas passed through the liquid is insufficient to 

 throw down the whole of the metal, the precipitate is, as 

 M. L. Gmelin observed, a chloro-sulphuret. This com- 

 pound becomes black by drying on the sand bath, and 

 exhales fumes of chlorine and antimony. 



Economical method of preparing the Protoxide of Copper, 

 by M. Malagute, {Ann. de Chim. liv. 216.) Fuse with a 

 gentle heat 100 parts of sulphate of copper, and 59 crystal- 

 lized carbonate of soda, and continue the heat until the 

 mass solidifies. Pulverize it, and add exactly 15 parts of 

 copper filings, then expose to a white heat, and keep it up 

 for twenty minutes. Powder the cooled mass, and wash it. 

 The residue is protoxide of copper, of a beautiful colour, 

 and the first washings contain sulphate of soda, which may 

 be extracted by evaporation. The oxide thus prepared costs 

 only 4s. 2d. for 2 lb. 2 oz. 2 dr. 



If we were content with calcining the sulphate with 

 copper, or employed anhydrous carbonate of soda, the pro- 

 duct would be less beautiful and less pure. The proportion 

 of carbonate of soda given is sufficient to decompose half of 

 the sulphate of copper, and a greater proportion, so far from 

 being advantageous, would afford an oxide much less pure. 



Separation of the Fixed Alkalies from Magnesia. — When 

 the alkalies and magnesia are in the state of chlorides, the 

 bases may be separated by converting them into sulphates, 

 treating the solution with acetate of barytes, heating them 

 after evaporation, and separating by water the soluble alka- 

 line carbonate from the carbonates of barytes and magnesia. 



Formerly, the separation was produced by a strong heat, 

 which converted the greatest part of the chloride of magne- 

 sium into magnesia, by the water of crystallization converting 



