254 



METALS. 



remarkable property of fusing in boiling water. Seve- 

 ral compounds of bismuth are used in medicine ; the 

 sub-nitrate, is also employed as a cosmetic. This 

 use of it is quite hazardous, as certain gases which are 

 often present in the air., have the effect, as will be here- 

 after seen, of changing its color to a deep brown or black. 



Copper de- 

 scription, 

 ores, solvents? 



COPPER. 



632. DESCRIPTION. Copper is a red, 

 malleable, and highly tenacious metal. It 



tam i shes in the ^ but ig ] ess i n j ure( } fty 



rust than iron, and therefore more durable. Nitric acid 

 is its proper solvent, and forms with it a green solution. 

 Copper is found in abundance, in the metallic condi- 

 tion, on the southern shore of Lake Superior. It is 

 chiseled out, in masses, from the rocks which contain 

 it. The metal is more commonly obtained from a 

 mineral, called copper pyrites, which is a double sul- 

 phuret of iron and copper. It is also found as pure 

 sulphuret, red oxide, and carbonate. Minute traces of 

 copper are found in human blood. 



633. PRODUCTION. Copper is prepared 



State briefly 



the mode of from the impure 



production. sulphuretj by 



first burning out the sulphur, 



in the air ; and secondly, 



heating with charcoal, to 



remove the oxygen which 



has taken its place. Sand 



is at the same time added, to form a floating slag with 



the oxide of iron, and thus remove it from the molten 



copper. 



