COPPER 



939 



thermometers and barometers, for dials, candlesticks, &c. To form this compound, 

 successive layers of copper clippings and white arsenic are put into an earthen crucible ; 

 which is then covered with sea-salt, closed with a lid, and gradually heated to redness. 

 If 2 parts of arsenic have been used with 5 of copper, the resulting compound com- 

 monly contains one-tenth of its weight of metallic arsenic. It is white, slightly 

 ductile, denser, and more fusible than copper, and without action on oxygon at ordinary 

 temperatures ; but, at higher heats, it is decomposed with the exhalation of arsenious 

 acid. The white copper of the Chinese consists of 40'4 copper; 31'6 nickel; 25'4 

 zinc ; and 2'6 iron. This alloy is nearly silver white ; it is very sonorous, well 

 polished, malleable at common temperatures, and even at a cherry red, but very brittle 

 at a red-white heat. When heated with contact of air, it oxidises, burning with a 

 white flame. Its specific gravity is 8'432. When worked with great care, it may 

 be reduced to thin leaves and wires as small as a needle. See GERMAN SILVER. 



Tutenag, formerly confounded with white copper, is a different composition from 

 the above. Keir says it is composed of copper, zinc, and iron ; and Dick describes it 

 as a short metal, of a greyish colour, and scarcely sonorous. The Chinese export it, 

 in large quantities, to India. 



M. Pelouze states that an alloy of equal parts of copper and nickel is greatly pre- 

 ferable to an alloy which contains also zinc. Even 2 of copper and 1 of nickel form a 

 valuable alloy. See PYRITES (!RON). 



COPPER, STATISTICS OF. During a term of about 30 years, the copper-mines have 

 sold their ores at the public sales. The following Table, from ' Eecords of Mining and 

 Metallurgy,' by Messrs. Phillips and Darlington, represents the progress of copper 

 mining from 1726 to 1855 : 



Copper Ore raised and sold in Cornwall and Devon in Decennial Periods for 126 

 Years, from 1725 to 1855. 



From 1855 to 1866 the following have been the quantities of copper produced in 

 Cornwall and Devonshire : 



