of vegetables, blended with bitumen and sulphur, or rather the vitriolic acid. And bitumens may reasonably be supposed, to have originated from subterraneous fires existing near strata of coal, and there dissolving the coal, giving rise to bitumenous sources. Bitumens, says Fourcroy, are combustible substances, solid, soft, or fluid; whose odour is strong, sharp, aromatic, and who appear to be a great deal more compounded than the bodies of the mineral reign. There are, however, diversities of opinion on this subject. Some think these combustible bodies belong to the mineral kingdom, and that they are to minerals, what oils and resins are to organic bodies. Others, and apparently with the most reason, insist that they proceed from organic substances, that is, animals and vegetables. Thus the successive beds of bitumens that are found in the bowels of the earth, announce them to have been deposited slowly, and by the waters. By the lapse of time, by saline or by other substances, they are indurated. The oils, and fat of marine animals, seem to have been one of the compositions used by nature to produce certain of them; while in the origin of others, the oils and resin of vegetables are palpable. Those beds beds of coal, says Romé de l'Isle, which form the greatest part of the bitumenous beds that have been yet discovered, are nothing but ancient deposits in the sea, or masses more or less considerable, of animals and vegetables, which, by the action of the vitriolic or marine acid on the oil, or fat matter of these substances, have become by degrees converted into bitumens.* These oils have sometimes been simply interposed in the substances, which have given them birth, and hence turf; sometimes they have flowed into cavities, and being modified by an acid, have passed into a state of bitumen, transparent or opake, as is observable in amber and jet; which former, in Prussia, is commonly found under a bed of turf, both being nearly of the same substance. The name of oil, by the way, by common consent, being given to that fat unctuous substance, which appears to belong exclusively to animals and vegetables. Six bitumens are known. Amber, asphaltum, or the bitumen of Judea, jet, coal, ambergris, and petroleum. Amber is the most beautiful of all the bitumens. Sophocles poetically affirmed, it was formed in India, by the tears of the sisters of Meleager, *Pallas. G 4 Meleager, changed into birds, and deploring the fate of their brother. Others, that Phaeton, burning the heavens and the earth, was precipitated by the thunder of Jove into the waters of Eridanus. There his sisters wept; and the precious tears falling into the waters. but not mixing with them, became solid without losing their transparency. It is capable of a fine polish. When it is rubbed for some time, it becomes electric, and attracts. straws and other light bodies, as we have already observed. It has been erroneously classed among the precious stones. The insects that are often found in it, prove it was once liquid. It is probable that amber is derived from a resinous juice, which flows from certain trees; and which, buried in the bowels of the earth, from the shocks the globe has experienced, there becomes impregnated with certain mineral and saline particles, and is consequently hardened. Other opinions, indeed, would fix it a solid mineral bitumen, not a vegetable resin, or inspissated juice, introduced into the cavities of the earth, and there indurated, and somewhat changed in its quality. They likewise would establish it an unequivocal terrene substance, though it is not unfrequently found in the sea. The The asphaltum, or bitumen of Judea, called also the gum of funerals; the karabé of Sodom; mountain pitch, balm of mummies, &c. is black, not very weighty, solid, and but little brilliant.* It breaks easily, and like a vitrification. While cold, it has no odour. It is found on the waters of the lake Asphaltus, or dead sea in Judea, near to the situations of the ancient cities of Sodom and Gomorrah. It is found also in other places. Its origin is supposed the same with the amber bitumen. ' Jet, called by the Latins gagas, and by Pliny named black amber, is a black, compact, hard bitumen; brittle and vitrificacious in breaking. Rubbed for some time, it attracts light bodies, and appears electric, like amber. Oil is got from it by distillation. Among the varieties. of opinions, the most probable as to its formation is, that it originates like amber, and hardens by lapse of time. Coal, is a black bitumenous substance found in the bowels of the earth. It lies generally in horizontal beds. Above this bitumen, beds of shells and fossil madrepores are frequently found. This has made naturalists generally believe, that coal has been formed by the deposition * Fourcroy. sition and acervation of oily, greasy parts of marine substances. There are different kinds of coal; one kind, remains black after its combustion; another gives spungy substances like scoria; and another, fibrous, as wood, is reduced to cinders. Coal yields a sulpurous smell, only when it contains pyritæ.* It contains an abundance of oil. It yields an abundance likewise of volatile alkali, which favors the opinion of its organic origin, as it is proved, that all animal bodies afford in distillation a salt of that nature. Ambergris, is a concrete bitumenous substance, of a soft though tenacious consistency, like wax. It appears evidently to have been in a fluid state, from the number of different things found in it, as the heads and feathers of birds, bones of fishes, &c. It is found floating on the sea. There is much difference in opinion relative to ambergris. Some believe it to be a sort of petroleum, which runs from rocks, thickened by the action of the sun and of salt water. Others conceive it to be the produce of an animal, viz. the excrement of birds who live on odoriferous herbs; or an inguinal secretion in whales, in whose stomachs it is often found. To the * Fourcroy. whale, |