Asphalt
2 of the 7 encyclopedias on this shelf carry an entry for Asphalt. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
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 2026 Editor's Note: Asphalt went on to pave the world: it surfaces the vast majority of roads, mixed with stone into the blacktop under every car. The 'small quantities' the entry knows became an industry fed by oil refining, though the astonis hing natural Pitch Lake of Trinidad — a self-renewing lake of tar — still supplies asphalt as it has for centuries. (Ed: BR 2026-06-03)
Collier's New Encyclopedia (1921)
or ASPHALTUM, the most common variety of bitumen; also called mineral pitch. Asphalt is a compact, glossy, brittle, black or brown mineral, which breaks with a polished fracture, melts easily with a strong pitchy odor when heated, and when pure burns without leaving any ashes. It is found in the earth in many parts of Asia, Europe, and the United States, and in a soft or liquid state on the surface of the Dead Sea, which, from its circumference, was called Asphaltites. It is of organic origin, the asphalt of the great Pitch Lake of Trinidad being derived from bituminous shales, containing vegetable remains in the process of transformation. Asphalt is produced artificially in making coal gas. What is known of asphalt rock is a limestone impregnated with bitumen, found in large quantities in Switzerland, France, Hanover, Holstein, Sicily, and other parts of Europe, and in the United States, the purest forms taking the names of elaterite, gilsonite, albertite, maltha, brea, etc. In the trade there is wide distinction between these and the sandstones, and limestones impregnated with bitumen, which are known as bituminous or asphaltic limestone, sandstone, etc. The latter are usually shipped without being previously treated or refined, and are used principally in street paving. The production of asphalt in the United States, produced from domestic petroleum, was in 1918, 527,575 tons, valued at $7,435,204. There were produced from Mexican petroleum in the same year 650,244 tons, valued at $10,- 324,200. The production of bitumines and allied substances in 1918 amounted to 60,034 tons, valued at $780,808. The crude asphalt imported into the United States in 1918 amounted to 114,686 short tons, valued at $624,967. There were exported in the same year 22,108 tons, valued at $577,654.