BISMUTH. 169 



Analytical reactions. 



1. Add to solution of copper, hydrosulphuric acid or am- 

 monium sulphide: a black precipitate of cupric sulphide is 

 formed : 



CuSO 4 + H 2 S H 2 SO 4 + CuS. 



2. Add sodium or potassium hydrate : a bluish precipitate of 

 cupric hydrate, Cu2HO, is formed, which is converted into dark 

 brown cupric oxide, CuO, by boiling. (See equation above.) 



3. Add ammonium hydrate: a dark blue solution is produced, 

 containing an ammonio-copper compound. (See explanation 

 above.) 



4. Add potassium ferrocyanide : a reddish-brown precipitate 

 of cupric ferrocyanide falls. 



5. Add solution of arsenious acid and carefully neutralize 

 with sodium hydrate : green cupric arsenite is precipitated. 



6. Add sodium or potassium carbonate : green cupric car- 

 bonate with hydrate is precipitated. 



7. Immerse a piece of iron or steel, showing a bright surface, 

 in an acidified solution of copper : the latter is precipitated upon 

 the iron, an equivalent amount of iron passing into solution : 



CuSO 4 + Fe = FeSO 4 + Cu. 



8. Compounds of copper (chloride especially) color the flame 

 green. 



9. Cupric compounds give a blue, cuprous compounds a red 

 borax bead. 



10. Cupric salts (when not anhydrous) have mostly a blue or 

 green color ; sulphate, nitrate, chloride, and the ammonio-copper 

 compounds are soluble, most other compounds are insoluble. 



Bismuth, Bi m = 210. Found in nature chielly in the metallic 

 state, disseminated, in veins, through various rocks. The ex- 

 traction of the metal is a mere mechanical process, the earthy 

 matter containing it being heated in iron cylinders, and the 

 melted bismuth collected in suitable receivers. 



Bismuth is grayish-white with a pinkish tinge, very brittle, 

 generally showing a distinct crystalline structure. It is occa- 

 sionally used in alloys and in the manufacture of a few medicinal 

 preparations. 



