Coke

the solid portion that remains after coal is subjected to intense heat. Coke is produced ordinarily in so-called coke ovens of the beehive type. One hundred bushels of coal are poured into the oven, which is then heated gradually to a temperature of 1400 deg. C. As soon as the heat reaches 100 deg. C. gas begins to escape; tarry products are given off up to 600 deg. C. First class coke rings with a metallic sound and has a silvery luster. It is of much importance in melting metals, as it burns with a pure flame without gas or smoke, and, being pure carbon, gives a most intense heat. In some sections of the country, where coke is in great demand for iron furnaces, the gas and tar products are sold cheaply as by-products, or allowed to go to waste. In the sections remote from the iron regions coal is heated for illuminating gas, and coke is a by-product. Where there is a demand it is sold chiefly as fuel. It is not so easily kindled as coal, but is an excellent fuel for heat. Coal is expected to yield about sixty-five per cent of its own weight in coke. The annual coke production of the United States is about 22,000,000 tons, over half of it in Pennsylvania; that of Great Britain is somewhat greater. See Charcoal; Coal; Gas