[ 192 ] [Book VI. 



CHAP. XXXII. 



COPPER. 



General Properties cf Copper. Its Natural Hiftory.- Turquoife Gem, 

 Smelting and refining cf Copper. Antique Statues preferred by the 

 Gresn Rit/f. Union with Acids. Blue Vitriol. Colouring cfGuns. 

 Cuprum Ammoniacum. Verdigris. Union with Metals. White 

 Copper. Pinchbeck. Gun Metal. Bell Metal.~Mctal of ancient 

 Slaiues. Bronze. Speculums of Reflecting Tele/copes. Pot Metal, 

 Tinning of Copper. 



COPPER is a metal of a peculiar red colour, 

 and when its furface is frefh and clean it has a 

 confiderable degree of fplendor. It is hard, ductile, 

 and malleable to a confiderab'e degree, and remarkably 

 fonorous. It has a peculiar and unpleafant fmell, par- 

 ticularly when rubbed. Its tafte is ftyptic and nau- 

 feous. Its tenacity is fuch, that a copper wire of one: 

 tenth cf an inch in diameter is capable of fupporting 

 a weight of about three hundred pounds. Its fracture 

 exhibits the appearance of fmall grains. Its gravity 

 is about nine times that of water. 



Copper has a great degree of ftrength and rigidity > 

 approaching to that of iron. It is nor inflammable 

 like iron, and is therefore iifed in gun-powder works, 

 inftead of that metal. It does not admit, like iron, 

 of being welded, but this defect is compenfated by its 

 greater fufibility, by which it may be always formed 

 into the defired Ihape. It requires for its fufion about 

 the fame heat as gold and fiiver. W hen in fufion, for 

 which it requires a ftrong white heat, it appears of a 

 blueifh green colour, which arifes from a flame of that 

 colour on its furface. By' a very violent heat it boils, 



and 



