PETROLEUM (ante), a natural rock-oil. composed principally of hydro-carbons, with bituminous elements, and essential oils. Long known in various parts of the world by its components appearing, either as bituminous springs on the surface, or floating on water, as nnplitha. See curl it is. in fact, a product of natural distillation in the for:natio:I of coal-measures, and occurs as a saturative with shales, clays and coals. Prof. Newbury long ago asserted that this was the case with the gralnunite of Virginia, destined to be largely used as an asphalt in street paving in this country. Similar, probably, are the asphalts of Trinidad and the Join. Soo ASPII ALT. Factories were established for manufacturing burning fluid from imported bog coal as early as 1834, but in 1858 the sinking of the first well changed them all to refineries. In this country the great supply of petroleum, and at present we market for the world, is in n.w. Pennsylvania, in two districts, an upper and lower. There are also districts, for as a rule, petroleum-wells are confined to an area which is always limited and well-defined, iu Ohio, West Virginia, and a large, but not profitable, area in California. Petroleum wells are sunk much as artesian wells (which see), reJes skating the erection of large frames, derricks, and the necessary machinery, etc., known as a " rig." A well may flow water, oil, or oil and water, depending upon the point struck in the internal reservoir. Flowing wells gradually diminish their delivery, aid finally have to he pumped. .0i] is found on any one of the different horizons above the Eocene, and therefore, varies in depth from over 2,000 to less than 200 feet. Three layers cf sand, found at varying distances apart in the first 900 ft., serve as a mark of depth in the oil region. The oil is stored in enormous tanks, and thence tram-ported to the refineries, to New York, the great center of export, or to the sea-board farther south. Pipe lines are now laid from the oil region to the principal refineries, and the receipts of the pipeline companies for so many barrels in tank are negotiable like certificates of grain-delivery. Oil-cars have iron tanks upon them, and oil-barrels are very strongly made, and often serve as return freight for Italian and German ships engaged in the export of oil. Oil is refined in a still (see DisTim.Arfox) by applying heat, and
cooling the worm. The first and highest products are the volatile oils. These are known under various names, and are used for portable or small local gas generators, air being allowed to mix in proper proportion with the material, and the vapor pumped or forced through tubes like common gas. See NAPBTRA. By applying artificial coolers a still more volatile product may be obtained. The last and heaviest products of distillation are the crude oils, dark and disagreeable in smell. They are sold at a low price, either to adulterate commercial petroleum, to be used as antiseptics, like coal-tar, or in extracting pa•affine. See PARAFFINE. The medium products are the burning-fluids of commerce, known under an infinity of names, and more or less refined or adulterated. The best kerosene is simply the best " run " of benzine, most carefully treated. The product is filtered, by centrifugt piston, or other filters, treated with ammonia or sulphuric acid, bleached, deodorized and relieved of the acid. The variety of appliances used in these processes is endless, but the work is accompanied by a noisome odor, and the production of several stinking and deleterious compounds, for which no efficient remedy has yet been discovered. From the heavier grades of middle oils and the finer crude oils, may be manufactured by careful treatment a sup:L rior article of machinery oil, now a very valuable export to England and the continent. The illuminating properties of all the products of petroleum depend upon their union in proper quantities with the air; the test of oils is their flashing point and their limn ing point, and varying as they do in different ratios, both should always be known. Stringent laws, based upon both these tests, can alone regulate traffic in such dangerous commodities. See OIL-WELLS, ante. The.yield of petroleum, estimated twenty years before at about a million barrels, increased as shown by the following table: 1880. 1879. 1878.
Number of hbls. of 42 gallons each, 15.765,800 16,036,000 13.750,000 Total exports 10,000,000 12,300,000 10,000,000 Home consumption or accumulation at sea-board... 5,705,800 3,736,000 3,750,008