LEAD. 65 



Protosulpliate of iron, green vitriol, prepared by dissolving iron 

 in sulphuric acid. It is crystalline — of a beautiful green colour — very 

 soluble — efflorescent. Sesquisulphate of iron, — made by action of 

 nitric acid on a solution of the protosulphate ; it has a buff colour, 

 and is sparingly soluble. There is only one carbonate — the proto- 

 carbonate ; this is sometimes found native, and exists in chalybeate 

 springs. There are two nitrates. 



The best tests for iron, are those mentioned under the head of the 

 sesquioxide. 



COPPER. 



Occurs sometimes in native crystals ; but, most commonly, as a 

 sulphuret, from which the metal is extracted by roasting with 

 charcoal. 



Prop. — The only red metal except titanium ; has considerable 

 lustre ; sp. gr. 8*6 ; is very ductile, malleable, and tenacious ; under- 

 goes but little change in dry air ; but, when moist, it is converted 

 into a subcarbonate. Symb. (Cuprum,) Cu. — Eq.31-6. Copper forms 

 two or three oxides. 



Dioxide or red oxide, Cu^O, occurs native, in octohedral crystals ; 

 may be formed by heating together the protoxide and copper filings. 

 It forms colourless salts with bases, which, however, are very un- 

 stable, from their tendency to absorb oxygen. 



Protoxide or black oxide, CuO, the basis of most of the salts of 

 copper; — prepared by calcining metallic copper, by precipitating from 

 any salt by an alkali, and by heating the nitrate. Colour varies 

 from a dark brown to a black. There is also a bi?ioxide. There 

 are two chlorides, iodides, and sulphides of copper, similar in com- 

 position to the first two oxides. 



The most important salts of copper are the sulphate, nitrate, car- 

 bonates, and acetates. The sulphate — well known in commerce, as 

 blue vitriol — is formed by the action of sulphuric acid on copper. 

 The carbonate occurs native, in the mineral malectite. Verdigris 

 is composed of one or more of the acetates of copper. The proper 

 solvent of copper is nitric acid. 



Tests. — Ammonia, in small quantities, throws down from a solu- 

 tion of the sulphate, the bluish-white hydrated protoxide ; but when 

 added in excess, it redissolves the precipitate, forming a deep blue 

 colour. Ferrocyanide of potassium gives a fine reddish-brown fer- 

 rocyanide of copper. It is also precipitated upon iron or steel. 

 Copper forms several important alloys, such as brass, with zinc ; 

 bell metal, with tin ; bronze, with zinc and lead. 



LEAD. 



Procured chiefly from the native sulphuret or galena, by roasting, 

 which converts most of it into a sulphate ; the sulphate and sul- 



6* 



