, Chap. 31:] Aft'wn of Salts oh Copper. iq$ 



feems rather to contribute to the prefervation of its 

 internal parts, as may be feen in antique medals and 

 Itatues of this metal. 



Copper does not unite with earthy matters ; its 

 calx, however, promotes their fufion, and forms with 

 them glafles of a deep brown. Cauftic fixed alkalies, 

 digefted in the cold with filings of copper, aiTume, after 

 a time, a light blue ' colour, the copper becoming co- 

 vered with a powder of the fame colour. Copper, 

 treated in the fame manner with volatile alkali, pro- 

 duces, in a few hours, a deep and moft beautiful blue, 

 the quantity of copper taken up being very inconfi- 

 derable. From the ftrong blue colour produced by 

 the action of copper and volatile alkali, they become 

 excellent tefts of the prefence of each other in any body, 

 fluid or folid. 



Copper is in general eafily acted on by acids. The 

 vitriolic acid, however, does not ad on it unlefs con- 

 centrated and affifted by heat ; it then corrodes the 

 copper into a brown matter of a thick confidence, 

 which, by the addition of water, affords a folution of 

 a deep blue colour. If this folution is evaporated to 

 a certain point, and fuffered to cool, long rhomboidal . 

 cryftals are afforded of a deep blue colour, called 

 vitriolated copper, or blue vitriol -, it appears therefore 

 that vitriolic acid forms, with iron, green cryftals ; 

 with zinc, white cryftals ; and with copper, blue cryA 

 tals. 



Copper may be obtained from the folutiori of blue 

 vitriol, by dipping into it pieces of iron. The vitri- 

 olic acid diffolves the iron in preference to the copper, 

 and depofits the latter, in its metallic form, on the fur- 

 face of the iron. Upon this circumftance is founded 

 the procefs for browning fowling-pieces. The barrels 

 O 2 arc 



