COPPER 



1573 



COPPER CLIFF 



The ore supplying the largest amount is 

 copper glance. Copper pyrites and copper car- 

 bonate are also valuable ores, and usually 

 contain lead and silver. The copper obtained 

 from the Lake Superior mines is in a nearly 

 pure state, and is easily obtained by crushing 

 the rock and separating the metal from it. 

 There are a number of compounds of copper 

 not ores, all of which are very poisonous. 



Preparation. Most of the ores contain sul- 

 phur and more or less rock that has no copper. 

 When taken from the mine these ores are 

 crushed and concentrated, that is, the copper- 

 bearing portion is separated from the waste 

 by running the crushed ore with water over 

 tables that are in constant vibration. The 

 copper-bearing rock, being the heavier, settles, 

 and the waste is washed away. The ore is 

 then roasted to drive off the sulphur, after 

 which it is smelted, forming matte, which is a 

 mixture of copper and slag. The matte is 

 again smelted, and the impurities are thus 

 removed. The metal obtained by the second 

 smelting is known as blister copper and is suf- 

 ficiently pure for ordinary usage. In some 

 works the Bessemer process is used; this pro- 

 duces blister copper from the ore. 



The purest copper is obtained from the 

 blister copper by electrolysis (which see). The 

 process consists in placing a quantity of the 

 impure metal in a tank containing a solution 

 of blue vitriol and a little sulphuric acid and 

 attaching it to the negative electrode, then 

 attaching a small piece of pure copper to the 

 positive electrode, and turning on a strong 

 current. The current dissolves the copper 

 from the mass at the negative electrode and 

 deposits it on the positive electrode, the same 

 as in electroplating, and the impurities fall 

 to the bottom of the tank. 



History. Copper has been known and used 

 longer than any other of the common metals. 

 The Egyptians were familiar with it at least 

 5,000 years before Christ, and possibly earlier. 

 It is often mentioned in the Old Testament; 

 tools of bronze are found side by side with 

 those of stone in Europe in dwellings of a 

 race so ancient that we cannot tell when they 

 lived. Some of the Indians around Lake Supe- 

 rior had hammer heads of copper when they 

 were first known to the Jesuit missionaries, 

 and these tools were the first evidence white 

 men obtained of the existence of copper in 

 this region. 



Copper Compounds. Most copper compounds 

 are blue or green in color. The most familiar 



is the sulphate, which, combined with water, 

 forms large blue crystals, known as bluestone, 

 or blue vitriol. When these crystals are heated 

 the water is driven off, and the uncombined 

 copper sulphate is left as a white powder. If 

 the white powder is allowed to stand in moist 

 air, or if it is dampened, it turns blue again. 

 Some copper compounds were formerly used 

 as blue and green pigments. Chief among 

 these was Paris green. All copper compounds 

 are poisonous, and Paris green is doubly so, as 

 it contains arsenic also. Neither it nor any 

 other copper compound is now much used in 

 paint. Copper compounds are often used to 

 kill fungi and insects injurious to plants; thus 

 potatoes are sprayed or dusted with Paris 

 green to poison beetles, seed grain is dipped 

 in copper sulphate solution to kill smut spores, 

 and Bordeaux mixture (made by mixing cop- 

 per sulphate solution with lime) is applied to 

 grape vines to destroy the mildew and to fruit 

 trees to rid them of fungi. J.F.S. 



Related Subjects. The reader is referred to 

 the following articles, in their alphabetical order 

 in these volumes : 



Alloy 

 Arizona 

 Brass 

 Bronze 

 Copper Glance 



Ductility 

 Michigan 

 Montana 



Steel (for Bessemer 

 Process ) 



COPPERAS, kop' eras, also known as GREEN 

 VITRIOL, is a compound of iron and sulphuric 

 acid, which occurs in light green crystals. It 

 has a puckery taste and a somewhat disagree- 

 able odor. When exposed to the air the crys- 

 tals absorb moisture and turn a rusty brown. 

 Copperas is extensively used in dyeing fabrics 

 black, and in the manufacture of ink and as 

 a disinfectant. It is made by decomposing iron 

 in sulphuric acid and by decomposing iron 

 pyrite, which is a compound of iron and sul- 

 phur. 



COPPER CLIFF, a mining town in the Sud- 

 bury district, Ontario, five miles west of the 

 town of Sudbury, on the Algoma Eastern and 

 the Soo line of the Canadian Pacific Railway. 

 At Sudbury connection is also made with the 

 Canadian Northern system. As its name indi- 

 cates, the town owes its origin to rich copper 

 deposits, which were first worked about 1887. 

 Later the mines were found to contain nickel, 

 and Copper Cliff now has the largest nickel 

 plant in the world. Practically the entire 

 town site and most of the buildings, including 

 a $250,000 hospital, completed in 1913, are 

 owned by the Canadian Copper Company, 



