Petroleum, or Rock Oil. - This is a liquid, inflammable substance, including benzole, naphtha, paraffine, asphatum, and various other articles. From time immemorial it has been found on the borders of the Caspian Sea, and to a limited extent it has been used for illuminating purposes. It has also been found in Burmah, Trinidad, Canada, and the United States. It was used by Indians as a medicament in different parts of New York and Pennsylvania; they found it floating on the surface of some of the streams flowing into the large rivers. It was first distilled at Pittsburg, in 1850, and about that time used for illuminating. It was in 1859 that the first successful boring was made, at Oil Creek, and shortly after the wells yielded about 1,000 barrels a day. Soon after it was found to richly repay well-sinking in Ohio, Virginia, and other States. Before many years millions after millions of barrels were brought to the surface. Chemists assert that the oil is the proceeds of animal bodies crushed in the subterraneous recesses of the earth, and their arguments seem to prove this theory. IT. S. surgeons have found it very effectual in curing gangrenous wounds. It has also many other valuable curative properties. In 1880 it was found in large quantities in Russian territory, and extensive works have been constructed to raise it and transport it to different parts of that empire. It now (1881) counts in value among the four or five articles exported from the United States.