Page:International Library of Technology, Volume 93.djvu/93

 4. An oil is 88 per cent, carbon and 12 per cent, hydrogen; how many cubic feet of air is required for the complete combustion of 1 pound? Ans. 188.48 cu. ft.

5. Required, the heat value per cubic foot of a gas having the following composition:

Constituents of Gas Per Cent. H 12 CH4 73 C2H4 13 CO 2 Ans. 989.07 B. T. U.

FUELS

PETROLEUM AND ITS PRODUCTS

OCCURRENCE AND ORIGIN

30. In its original or crude state, petroleum is usually found as a dark-brown liquid. Its color, however, varies from that of pure water to a tarry black. It has a greasy feeling and a fatty appearance, the heavier and darker kinds having the consistency of heavy molasses. Usually, the odor is disagreeable, being particularly offensive when sulphur is present in the oil. Water-clear petroleum is of very rare occurrence, and is found only in Persia and at Smith's Ferry, Pennsylvania. Petroleum, like many minerals, is found at various depths beneath the earth's surface. It has been found in springs, oozing from the ground, in shallow wells, and in artesian wells many thousand feet deep. In the United States, it is found in one or the other of its various forms in almost every state. In the state of Pennsylvania, the Indians formerly gathered the oil from the surface of the water in salt marshes, while in the Russian Caucasus large springs have been known for centuries. There is scarcely any division of the earth's surface that has not a deposit of petroleum. The most important of these, however, are the deposits at Baku, on the shores