580 COPPER. 



forms a corresponding subchloride of copper, which is soluble 

 in hydrochloric acid. The hydrated alkalies precipitate a 

 hydrated suboxide from that solution, of a lively yellow colour, 

 which changes rapidly in air from absorption of oxygen. 



Suboxide of copper is also formed when copper is placed in a 

 dilute solution of ammonia, containing air, and is dissolved by 

 the alkali. If the ammonia has been corked up in a bottle with 

 copper for some time, the liquid is colourless ; but on pouring 

 it out in a thin stream, it immediately becomes blue, by absorb- 

 ing oxygen. The liquid may be again deprived of colour by 

 returning it to the bottle, and closing it up, in contact with the 

 metal. 



Compounds have been obtained of suboxide of copper with 

 several acids, particularly with sulphurous acid, the sulphite 

 forming a double salt with sulphite of potash, Cu 2 O, SO 2 + 

 2(KO, SO 2 ), with hyposulphurous acid, with sulphuric, car- 

 bonic and acetic acids. When fused with vitreous matter, the 

 suboxide of copper gives a beautiful ruby red glass ; but it is 

 difficult to prevent the suboxide from absorbing oxygen, when 

 the glass becomes green. 



Subsulphuret of copper, Cu 2 S, forms the mineral copper 

 glance, and is also a constituent of copper pyrites. It is a 

 powerful sulphur base. Copper filings, mixed with half their 

 weight of sulphur, when heated, unite with intense ignition, and 

 form this subsulphuret. 



Subchloride of copper, Cu 2 Cl, may be prepared by heating 

 copper filings with twice their weight of corrosive sublimate. 

 It was obtained by Mitscherlich in tetrahedrons, by dissolving 

 in hydrochloric acid the subchloride of copper formed on mixing 

 solutions of pro to chlorides of copper and tin, and allowing the 

 concentrated solution to cool. Subchloride of copper so pre- 

 pared is white, insoluble in water, soluble in hydrochloric acid, 

 but precipitated by dilution. It is dissolved by a boiling solu- 

 tion of chloride of potassium, which, if allowed to cool in a close 

 vessel, yields large octohedral crystals of a double chloride : 

 Cu 2 Cl-f 2KC1 ; they are anhydrous. It is remarkable that the 

 forms of this double salt, and of both its constituents, all be- 

 long to the regular system.* 



Subiodide of copper, Cu 2 I, is a white insoluble precipitate, 



* MftsdieiHch in Poggendorff s Annalcn, 49, 401. 1840- 



