Asphalt

as'falt, a dark, pitchy, material which, according to one theory, is the result of decomposition of vegetable or animal matter. It appears to be oxidized petroleum. Artificial asphalt, in small quantities, is evolved as a by-product from coal in the making of illuminating gas. Asphalt solidifies when cold, and whether liquid or solid, is insoluble in water. It varies in color from black to a dark brown, but always has a strong, pitchy odor. Asphalt is found in small quantities in Switzerland, in eastern Scotland, in Alsace, in Mesopotamia. Asphalt springs occur abundantly on the shores of the Dead Sea, where it is known to the Arabs as Moses' stone. The greater part of the western world's supply of asphalt, however, is obtained from the island of Trinidad, where a large pitch lake occurs. This lake is about half a mile in diameter and is supposed to be eighty feet deep. Around the shores, the surface is covered with hardened asphalt, but the center is hot and steaming. When the wind blows away from shore, the crusty asphalt is broken into pieces and is sent down to ships in the harbor by means of buckets running on an overhead cable.

An American company has obtained possession of an asphalt lake at Bermudez, Venezuela. This lake is two miles wide. The crusty asphalt is quarried like ice. Liquid asphalt rises as fast as the blocks are removed.

Wooden ships, piling, bridge timbers, and other wooden works exposed to sea water are saturated with hot asphalt as a protection against the ravages of the toredo or borer. About the middle of the nineteenth century asphalt came into use for street paving. The asphalt boulevards of Paris are notable. Its use for this purpose has become general in leading North American cities. The asphalt is first heated in a huge kettle, then mixed with gravel and coarse sand. It is laid in place when hot, rolled heavily, and coated with a sifting of sand. In mild climates it makes a cleanly, elastic, and gratefully quiet pavement, being especially desirable for residence streets. Asphalt is not, however, sufficiently durable for streets with heavy dray traffic. It is open to the further objection of becoming slippery in sleety weather, and of heaving and cracking in northern latitudes. In Washington, D. C., it is the material of all others employed in paving the boulevards which radiate from the Capitol. Broad Street, Philadelphia, has seven miles of asphalt paving.

See Trinidad