USEFUL METM.< 161 



:irisc tioin the segregation of the copper in the alloy into 

 Hot boxes may arise from three causes: (1) Segregation of the 

 metal into spots capable of producing intense heat through fric- 

 tion; (2) too coarse a crystalline structure of the alloy, and (3) 

 the presence of dross. Imperfect lubrication plays a very minor 

 part. 



Aluminum bronze as the name implies is an alloy of copper 

 and aluminum. These various alloys are widely used in the arts. 

 One of these consist of 90 per cent, copper and 10 per cent, of 

 aluminum. If the percentage of aluminum falls below 5 or rises 

 above 10 the bronzes are of little techincal value. 



Copper amalgams are used wherever a change from a plastic 

 to a solid state is desired. They are used to some extent in filling 

 teeth. 



One of the new uses to which copper has been successfully 

 applied is the coating of railroad passenger cars, forming a sub- 

 stitute for paint and varnish. The sheet copper used on the sides 

 is 0.012 in. in thickness and fastened to the wood by invisible 

 screws. When in place the copper is washed with a weak acid 

 solution, and the shellaced or lacquered. 



Copper oxide has come into a new use in the painting of the 

 bottom of ships. This forms a substitute for copper sheathing. 

 Copper oxide is used in refining petroleum. The gas is absorbed 

 by the copper oxide forming the sulphide of copper and water. 

 The oxide is regenerated by roasting the sulphide. Cupric oxide 

 is used in the Edison LeLande electric battery, which consists 

 of a zinc element and one of copper oxide. The battery is said 

 to be one of the most economical and durable in the American 

 market. Cupric oxide is used also in coloring glass, the green 

 and the blue depending largely upon the manipulation. Copper 

 oxide is used in the tile and glazed brick industries for decorative 

 effect. It is also used in the oxidation of organic matter for it is 

 an efficient oxidizing agent under heat. 



The output of copper in 1906 was $177,595,888. The 

 smelter production of copper in 1911 in the United States ex- 

 ceeded 1,000,000,000 Ibs. 



Cadmium: Its Properties, Occurrences and Uses 



Properties. Cadmium, symbol Cd, is a bluish white, ductile. 

 malleable and sectile metal. It tarnishes upon exposure to the 

 11 



