ABSTRACT
Petroleum products are made from petroleum crude oil and natural gas, Similar products are made from other natural resources such as coal, peat, lignite, shale oil, and ta r sands. Products from these other sources are frequently called “synthetic,” even though their properties can be indistin guishable from crude oil derived products. Here the term “synthetic" is intended to denote the products came from a raw material other than the more common sources, crude oil or natural gas.
