Asphalt is produced by the distillation of petroleum, but the greater part of the world's product comes from two "pitch lakes"—one in Bermudez, Venezuela, the other in the island of Trinidad, off the Venezuelan coast. The former is the larger and produces a superior quality. Small deposits occur near Los Angeles, Cal., and in Utah. The output of the Venezuelan asphalt is used almost wholly for street pavement.
Probably no other mineral has had a wider influence on both social and economic life, and the industrial arts, than petroleum and its compounds. The kerosene lamp, the aniline dye, the insulation of electric wires, the lubrication of machinery, the cosmetic, the india-rubber solution, and the physician's sedative dose represent only a few of the devices that are derived from petroleum.
Natural Gas.—A natural inflammable gas occurs in or near several of the petroleum horizons. One important belt extends through western Pennsylvania and New York, and another through northwestern Ohio and northeastern Indiana. It is conveyed through pipe-lines and used both as fuel and for lighting. Natural gas occurs in a great many localities, but is used commercially only in the regions noted. It is better adapted for making glass than any other fuel, and on this account extensive glass-making establishments have concentrated in the natural-gas belt of western Pennsylvania.
QUESTIONS FOR DISCUSSION
The statement is sometimes made to the effect that coal is "condensed sunlight"; is it true, or untrue; and why?
Why are the coal areas of Europe and America also areas of various manufactures?
A recent cartoon had for its title—"John Bull and his coal piles (i.e., coaling stations) rule the world"; show why this statement contains a great deal of truth.
What are some of the advantages of steam-vessels over sailing-vessels?
Whale oil, crude turpentine, kerosene, and gas have been used each in turn for illuminants; what is the advantage of each over the preceding?
Describe the structure of an ordinary kerosene lamp-burner, an argand burner, a Welsbach burner.