109 



COPPER. 



Copper is sometimes found native, but in very 

 small quantities. It is generally met with in the 

 state of oxide, or united to sulphur, or to acids. 

 In Cornwall there are very rich mines of copper. 



Pure copper is of a red colour, very tenacious, 

 ductile, and malleable. It melts at 27 of Wedge- 

 wood's pyrometer, and burns with a green flame. 



It is not oxided by water. When exposed to a 

 red heat, it becomes covered with a crust of oxide 

 of a blackish colour, this is the peroxide of copper. 

 The fir^t, or protoxide, is of a red colour when 

 found native,but when formed artificially is orange. 



The oxides of copper are reduced to the metal- 

 lic state by heating with charcoal or oils. 



The nitric acid disolves copper with efferves- 

 cence, and the solution has a blue colour. The 

 acid first oxidates the metal, a large quantity of 

 nitric oxide (nitrous gas), is disengaged, and the 

 oxide dissolves ; this forms the nitrate of copper. 



The sulphuric acid does not dissolve copper un- 

 less when concentrated, and in a boiling state. 

 Fine blue crystals, which are the sulphate of copper, 

 are the result. This is what is commonly called 

 blue vitriol. This salt is decomposed by iron ; for 

 if a piece of iron be immersed in a solution of sul- 

 phate of copper, the copper will be precipitated 

 upon the iron. This process is often employed for 

 procuring the copper from the water in copper 

 mines, which has in it a large portion of sulphate 

 of copper. 



The muriatic acid does not act upon copper ex- 

 cept in a state of ebullition, and then the muriate 



