ASPHALTUM, in chemistry, one ofthe proper bitumens, found in great abun dance in different countries, especially in the island of Trinidad, on the shores of the Red Sea, and in Albania, where it is found in vast strata. It is supposed that it was first liquid, and that it acquired solidity by exposure to the air. Its colour is black, with a shade of brown, red, or grey. Its specific gravity varies. That of Albania, as ascertained by ICIaproth, was 1.20; but it was somewhat contami nated with earth. Kirwan, in purer spe cimens, found the specific gravity to vary from 1.07 to 1.16. Klaproth has lately published an analysis of the asphaltum of Albania. He found it insoluble, both in acids and alkalies, as also in water and alcohol; but soluble in oils, petroleum, and sulphuric ether. Five parts of recti fied petroleum dissolved one part of as phaltum without the assistance of heat, and formed a blackish brown solution, which, by gentle evaporation, left the as phaltum in the state of a black brown shining varnish. The solution in ether was of a pale brown red colour ; and when evaporated, the asphaltum remain ed in the state of a semifluid substance, of a reddish colour, still insoluble in al cohol. A hundred grains of this asphal tum being distilled in a retort, by a heat gradually raised to redness, yielded the following products.
Grains.
Heavy inflammable air 16 A light brown fluid oil 32 Water slightly tainted with ammonia 6 Charcoal 30 Ashes . . . 16
100 These ashes consisted chiefly of silica and alumina, with some iron, lime, and manganese. The asphaltum found in Al bania is supposed to have constitutedthe chief ingredient of the Greek fire. The Egyptians are said to have employed this bitumen in embalming. It was called, mumia mineralis. The ancients inform us that it was used instead of mortar in building the walls of Babylon. The Ara bians still use a solution of it in oil to be smear their horse harness, to preserve it from insects. Buildings are said to be constructed with this pitch ; and Peter de Vol mentions, that he examined very old buildings, the stones of which were cemented by means of mineral pitch ; and which were still firm and good. Asphal tum is seldom absolutely pure ; for when alcohol is digested on it, the colour of the liquid becomes yellow, and, by gentle evaporation, a portion of petroleum is se parated. Mineral tar seems to be nothing else than asphaltum containing a still greater proportion of petroleum. When alcohol is digested on it, a considerable quantity of that oil is taken up ; but there remains a black fluid substance like melt ed pitch, not acted upon by alcohol, and which therefore appears to possess the properties of asphaltum, with the excep tion of not being solid. By exposure to the air, it is said to assume gradually the state of asphaltum.