mutation of metals. Metallic iron 

 placed in certain solutions of unknown 

 composition possessed the power to 

 precipitate metallic copper. With all 

 the wondrous faith in the problems of 

 alchemy the phenomenon was inter 

 preted as one of transmutation and 

 the statement made that iron had been 

 transformed into copper. 



Within the last few years a remark 

 able increase in the output of the cop 

 per mines of the world has been re 

 corded. This is due mainly to the de 

 mand for copper on account of the 

 great strides in electrical achievements 

 during recerit years. Yet there is no 

 doubt that the world's supply is wholly 

 adequate to meet demands on it for a 

 long period to come. The high con 

 ductivity of copper renders it espe 

 cially useful for conveying electric 

 currents and its most important use at 

 present is in electricity. However, it 

 is also a common convenience in many 

 arts. Its alloys are numerous, bronze 

 and brass being the most common. 

 Bronze is an alloy of copper and tin 

 and brass of copper and zinc. The 

 manufacturer of bronze bells finds 

 opportunity for an interesting study of 

 the alloy used in his product. The 

 varying tones of bells are due to the 

 different percentages of copper and 

 tin used in the bell metal. 



In locality and mode of occurrence 

 lead is somewhat closely allied with 

 copper, and the ores of lead and zinc 

 are almostinvariably associated. Hence 

 a description of lead naturally follows 

 that of copper and may also be under 

 stood as typical, so far as occurrence 

 and mining methods are concerned, for 

 that of zinc. 



Lead occurs in nature chiefly in the 

 forms of the sulphide, galenite or ga 

 lena, the sulphate, anglesite and the 

 carbonate, 'cerussite. Galena is lead- 

 gray, quite soft, and frequently occurs 

 in a coarsely crystalline condition, the 

 crystals often being cubical. The lus 

 ter is metallic, hence a superficial ex 

 amination of a specimen might result 



in mistaking the mineral for the copper 

 ore, chalcopyrite, already described. 

 The streak will serve to identify any 

 specimen, however, it being a lead- 

 gray of much lighter shade than that 

 of chalcocite. Anglesite and cerussite 

 are far less abundant than galena. The 

 former varies from white through gray 

 to yellow and has a resinous luster. 

 Cerussite is white or gray, resembling 

 anglesite, and has a brilliant, vitreous 

 luster. Both minerals, like galena, are 

 soft and easily scratched with a knife. 



The ores of lead are widely distrib 

 uted throughout the United States and 

 it is difficult to assign boundaries to 

 special districts. Galena occurs in 

 small quantities too small for profit 

 able working throughout the Appa 

 lachian region, and is found in paying 

 quantities in what is known as the 

 Missouri lead district. In the Colo 

 rado and other western mines the ore 

 is found in silver-bearing veins. Were 

 it not for the presence of silver in those 

 veins the production of lead from them 

 would probably practically cease, as 

 the anglesite, the principal lead ore of 

 the veins, does not occur in amount to 

 pay for working the mines for that 

 product alone. 



White lead, used in paints, is the 

 most important use of the metal. Paint 

 ers prefer the product to zinc-white 

 chiefly because it is much more opaque 

 and possesses a much greater covering 

 power. Much lead is made into pipes 

 for conveying water. Pure lead is not 

 used for the making of shot, but in 

 stead an alloy of lead and arsenic. 

 Unlike pure lead, the alloy assumes a 

 spherical form when dropped through 

 the air. " Shot towers" are constructed 

 to make use of this property in the 

 manufacture of shot. The demands 

 for lead have not been increased by 

 recent extraordinary development of 

 any of the arts employing the metal, 

 hence the world's output of lead dur 

 ing the past decade has had a normal 

 increase. For the year 1897 tne total 

 production of lead was 725,200 metric 

 tons. 



140 



