MESSRS. EVELETH, BISSELL AND REED.
Gentlemen:—I herewith offer you the results of my somewhat extended researches upon the rock-oil, or petroleum, from Venango County, Pennsylvania, which you have requested me to examine with reference to its value for economical purposes.
Numerous localities, well known in different parts of the world, furnish an oily fluid exuding from the surface of the earth, sometimes alone in "tar springs," as they are called in the Western United States; frequently it is found floating upon the surface of water in a thin film, with rainbow colours, or in dark globules, that may, by me chanical means, be separated from the fluid on which it swims.
In some places wells are sunk for the purpose of accumulating the product in a situation convenient for collection by pumping the water out. The oil exudes on the shores of lakes and lagoons, or rises from springs beneath the beds of rivers. Such are the springs of Baku, in Persia, and the wells of Amiano, in the duchy of Parma, in Italy. The usual geological position of the rocks furnishing this natural product is in the coal measures—but it is by no means confined to this group of rocks, since it has been found in deposits much more recent, and also in those that are older—but in whatever deposits it may occur, it is uniformly regarded as a product of vegetable decomposition. Whether this decomposition has been effected by fermentation only, or by the aid of an elevated temperature, and distilled by heated vapour, is perhaps hardly settled.
It is interesting, however, in this connection to remember that the distillation, at an elevated temperature, of certain black, bituminous shales in England and France has furnished large quantities of an oil having many points of resemblance with naphtha, the name given to this colourless oil, which is the usual product of distilling petroleum.
The very high boiling point of most of the products of the distillation of the rock oil from Venango County, Pennsylvania, would seem to indicate that it was a pyro genic (fire-produced) product.
_ _ Bitumen, asphaltum, mineral pitch, chapapote, etc., etc., are names variously given to the more or less hard, black, resinous substance which is produced usually from the exposure of petroleum to the air, and is found either with or without the fluid naphtha or petroleum. The most remarkable examples of the occurrence of these substances, so intimately connected with the history of rock-oil, are the Lake Asphal tites of the Dead Sea, so memorable in history, the well-known Bitumen Lake of Trinidad, and the deposits of mineral pitch or chapapote in Cuba. In one of the provinces of India, vast quantities of petroleum are annually produced, the chief con sumption being local, for fuel and lights, but a portion is also exported to Europe for the production of naphtha. In the United States, many points on the Ohio and its tributaries are noted as producing this oil; nearly all of them within the coal meas ures. A detailed history of these various localities can be found recorded in books of science, and their repetition here would be out of place.