COPPER ORES. 297 



decomposition of the sulphurels and other ores. At the Hi- 

 wassee mine, PolU Co., Tennessee, it is abundant, and is 

 worked as an ore. It was found of excellent quality in the 

 Lake Superior copper region, but has there been exhausted. 

 The oxyds of copper are easily smelted by heatirTg with 

 the aid of charcoal alone. They may be converted directly 

 into the sulphate or blue vitriol, by means of sulphuric acid, 

 but are more valuable for the copper they afford. 



blue vitriol. — Sulphate of Copper. ^ife— 



Triclinic. In oblique rhomboidal prisms. Also as an 

 efflorescence or incrustation. 



Color deep sky-blue. Streak uncolored. Subtransparent 

 to translucent. Luster vitreous. Soluble, taste nauseous 

 and metallic. H=2— 2*5. Gi=2*2l. 



Composition: sulphuric acid 32*1, oxyd of copper, 3T8, 

 water 36*1. A polished plate of iron in a solution becomes 

 covered with copper. 



Obs. Occurs with the sulphurets of copper as a result of 

 their decomposition, and is often in solution in the waters 

 flowing from copper mines. Occurs in the Hartz, at Fahlun 

 in Sweden, and in many other copper regions. 



Uses. Blue vitriol is much used in dyeing operations and 

 in the printing of cotton and linen ; also for various other 

 purposes in the arts. It has been employed to prevent dry 

 rot, by steeping wood in its solution : and it is a powerful 

 preservative of animal substances ; when imbued with it and 

 dried, they remain unaltered. It is afforded by the decom- 

 position of copper pyrites, in the same manner as green vit- 

 riol from iron pyrites, (p. 213.) 



It is manufactured for the arts from old sheathing copper, 

 copper turnings, and copper refinery scales. The scales are 

 readily dissolved in dilute sulphuric acid at the temperature 

 of ebullition ; the solution obtained is evaporated to the point 

 where crystallization will take place on cooling. Metallic 

 copper is exposed in hot rooms to the atmosphere after it has 

 been wet in weak sulphuric acid. By alternate wetting and 

 exposure, it is rapidly corroded, and affords a solution \vhic l i 



What is blue vitriol ? Describe it. What is said of its mode of oc- 

 currence 1 For what is it used ? How is it manufactured in the arts? 

 How is copper obtained from solutions in some mines ? Describe 

 green malachite. 



