PETROLEUM A heavy, liquid, flammable oil stored under the surface of the earth, and originally formed as the by-product of the action of bacterium on marine plants and animals. It consists chiefly of carbon and h in the form of hydrocarbons, including most of the liq- uids of the paraffin series, C5H12 to C16H34, together with some of the gases, CH4 to C4H10, and most of the solids of the series from C17H36 to C27H56. It also contains hydrocarbons of other series. While petroleum is used primarily for the production of fuels and lubricating oils, it is one of the most valuable raw materials for a very wide range of chemicals. The name petrochemicals is used in a general sense to mean chemicals derived from petroleum, but it does not mean any particular class of chemicals. Sulfur and he ar by products from petroleum working.Petroleums from different localities differ in composition, but tests of oils from all parts of the world give the limits as 83 to 87% carbon,11 to 14 hydrogen, with sulfur, nitrogen, and oxygen in amounts from traces to 3%. Mexican and Texan oils ar high in sulfur. The crude oil is split by distillate into naphtha, gasoline, kerosene, lubricating oils, paraffin, and asphalt.

PETROLEUM