BITUMEN

the name of a spedes in mineralogy, the individuals composing which have acquired distinct names from their diversity in appearance. This depends chiefly upon their state of aggregation, whid i forms an uninterrupted series from fectly fluid to the solid condition. Naphtha, the most fluid variety, is nearly le , or of a ydlowish tinge, transparent, and peculiar odour. It swims on water, its specific vity being from 0*71 to 0'84. It bums with white flame and thick smoke, and leaves no It consists of carbon 82*20, and hydrogen 14*80. is found on the peninsula of Apsheron, upon western shore of the Caspian Sea, where through a marly soil in the form of vapour, and, made to flow through earthen tubes, is burned purpose of a isting in the preparation of food. collected by sinking pits sevend yards in depth, which the naphtha flows. It is burned in lamps the Persians instead of oil. With certain vegetable oils, naphtha is said to form a good varnish. The variety petroUiem is more abundant naphtha^ from which it appears to differ being thicker. In consistence it resembles tar. It is of a strong disagreeable odour, and ish or reddish brown in colour. It occurs, oozing of locks, in the vicinity of beds of coal, or upon the surface of springs. The strata from this oil proceeds belong to the Devonian formation, and lie under the sandstone and limestone strata. existence of this oil was known to the ancients, Hero dot us makes mention of oil-springs in the of Zante; but it is only within the last few years it has been applied to any great extent to practical Inrd strange purposes. Springs of petroleum are now Imown to and exist in many different parts of the world— in Emx)pe, ia Asia, Africa, and above all in America. In Europe of the prindpal places in which it is found are Abace, than Neuf chatel in Switzerland, several parts of Italy, and is very largdy in Galida. In Asia petroleum is found bars of most abundantly in the Bizman Empire, where the with wells have been worked for centuries. The yearly neck product is now said to be about half a million hogs about heads, each 6 cwts. But no region is so rich in petrothe leum, or po e es it in a situation so convenient for It commerce, as the so-called great basin in North is an America extending from the Western Allegbanies when, to the Rocky Mountains, and from the valley of the severe Little Kanawha in Virginia to Lake Ontario. Yenor bush an go county, with the Oil-creek in Pennsylvaiua, reeds, and the valley of the Kanawha in Vizginia, are parare four ticularly productive. The first petroleum welk in colour. America were discovered in 1859, and since that tome when it has risen to be a leading artide in the foreign trade of the United States. severe is the Elastic bitumen is soft, flexible, and elastic. It a native emits a strong bituminous odour, and its specific graof vity is about the same as that of water. On expo inches in sure to the air it becomes hard, and loses its elastiblack, dty. It is sometimes called mineral caoutchouc, be thighs cause it takes up the traces of crayons in the same fenude manner as the caoutchouc or indian-rubber. It ia in found in the lead-mines of Derby shire, at St Berhas nard's Well, Edinburgh, in France, and elsewhere. Compact bitumen, or atphaltum, is of a Bhining more black colour, solid, and brittle, with a ooochoidal fracture; specific gravity 1 to 1'6. Like the former res i varieties, it bums freely, and leaves but little readue. salt It is found in Judea, in the Palatinate, in Franoe, in salts of Switzerland, and in large deposits in sandstone in it ia Albania. In the island of Trinidad it forms a lake of the three miles in circumference, and of a thickne unknown. The bricks of which the walls of Babylon See were built were cemented with hot bitumen. The well-known asphalt pavement is formed by mixing melted bitumen with graveL seveial BIVALVE SHELLS, or Bivalves. See Mol- LUSOA.