ASPHALT MINING, in the ease of rock asphalt, is usually a simple process, in which blasting is employed to loosen the rock. In the Seyssel Mines, in France, the bituminous limestone is blasted from between layers of ordinary white limestone, and the work done for the most part underground. In the United States, the Ken tucky bituminous sandstone and the bituminous limestone of Texas are worked from the surface, after stripping off the overlying material. The MEP general process seems to be employed elsewhere in the United States. In Santa Bar bara County, Cal.. a deposit of sand impreg nated with bitumen is mined by first using a powerful hydraulic jet, supplied by a steam pump and water-pipe. Sonic 11 to 8 feet of loam is thus washed into the ocean; and after a thin layer of clay is spaded off, the bitumi nous sand is then thrown into cable ears by men with hot spades, and hauled up an incline to the refinery. By far the most interesting and expensive asphalt mining and refining plant in the world is that which produces the California Alcatraz product, and which is also located in Santa Barbara County. The asphaltic sand stone is mined at Sisquac, by open-face blasting, and the rock loaded on to a cable car by means of an electric crane and hauled to crushing rolls. Its subsequent treatment to reduce it to a liquid condition for piping to the refilling plant, 30 miles distant, is described below, under Asphalt Refining.
The lake asphalts of Trinidad and of Ber mudez are mined in a simple but interesting manner. The Trinidad asphalt is dug by means of picks before daylight, when brittle. It is loaded into buckets, placed on flat ears which inn on a cable railway extending out onto the asphalt deposit. This railway is supported on palm branches, to prevent its settling into the asphalt, and at its shore end the buckets of asphalt are hoisted by hydraulic power and then conveyed on an atrial cableway to a pier 1700 feet in length, with its head in 30 feet of salt water. The contents of the buckets are
dumped directly into the holds of vessels, and the empty buckets are sent hack up to the lake as the heavy ones come down. The aerial cable way is about 3400 feet in length. half over the land and half over the water, and had in 1000 a capacity of 70 tons per hour. (Sec CABLEWAY, for description of this method of transportation.) Adjoining the Trinidad lake-asphalt deposit is found the so-called land asphalt. This is de scribed as an overllinv from the lake, and is harder and more brittle than the lake product. lt occurs in pockets and other isolated deposits, from which it is dug out, carted to the beach, placed on lighters, and conveyed to and loaded on ocean vessels.
:NA the Bermudez Lake the asphalt is exca vated in practically the same way as at Trini dad: but it is loaded into hand-ears running on a portable track. On shore the ears are dumped into boxes placed on fiat ears. which are hauled by a locomotive about 5 miles to a wharf on the Guanoco Ilive•. If a vessel is at hand, the asphalt. is dumped directly into its hold; otherwise it is stored on shore. The Ber mudez product is softer than that from Trini dad. It is so soft that the holds of the trans ports must be divided into compartments to prevent flowing to one side and giving the ships a permanent list. There is a small refining plant on the shore at the Trinidad Lake, and in 1900 one was being erected at the Bermudez shipping wharf. Most of the asphalt from these two sources is refined after ocean shipment.