158 DESCRIPTIONS O MINERALS. 
Composition. Cu O,5+5 aq=Sulphuric acid (or sulphur 
trioxide) 32:1, copper oxide 31°8, water 36:1. A polished 
plate of iron in solutions becomes covered with copper. 
Obs. Occurs with the sulphides 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 foreign copper regions; in 
the Hiwassee copper mine, Tennessee ; Ss uiie Canton mino, 
Georgia ; at Copiapo, Chili. 
Blue vitriol is much used in dyeing operations and in the 
printing of cotton and linen; also for various other pur- 
poses in the arts. It has been employed to prevent dry rot, 
by steeping wood in its solution: and 1t is a powerful pre- 
servative 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 ; but it is manufactured for the arts, 
chiefly from old sheathing- -copper, copper turnings, and cop- 
per refinery scales. 
In Frederick County, Maryland, blue vitriol is made from 
a black earth which is an impure oxide of copper with com 
per pyrites. 
In some mines, the solution of sulphate of copper is so 
abundant as to afford considerable copper, which is obtained 
by immersing clean iron in it, and is called copper of cemen- 
tation. At the copper springs of Wicklow, Ireland, about 
500 tons of iron were laid at one time in the pits; in about 
12 months the bars were dissolved, and every ton of iron 
yielded a ton and a half, and sometimes nearly two tons, of 
a precipitated reddish mud, each ton of which produced 16 
ewt. of pure copper. The Rio Tinto Mine in Spain is an- 
other instance of working the sulphate in solution. These 
waters yleld annually 1,800 cwt. of copper, and consume 
2,400 cwt. of iron. 
Brochantite. An insoluble copper sulphate, containing 17°7 per 
cent. of sulphur trioxide. Color emerald-green. In tabular rhombic 
crystals, from the Urals, Retzbanya, Cornwall, Mexico, Chili, Aus- 
tralia. Krisuvigite and Konigite are the same species. 
Langite, Cyanotrichite (Velvet copper ore), Krénkite, Philippittc, 
Enysite, Linarite, Dolerophanite, Hydroe yanite, are other sulphates 
containing copper, the last two anhydrous ; and Connellite is another 
containing chlorine, from Cornwall. 
The Copper tungstate, Cuprotungstite, occurs of a yellowish-green 
color in Chili. 

