The chemical industry depends very heavily on petroleum and natural gas as sources of raw materials. It is likely that in excess of 80% of the literally thousands of different basic organic chemicals employed today are derived from these sources. The petrochemical industry has grown with the petroleum industry. As is the case with the latest trends in changing crude oil types, it must also evolve to meet changing technological and humanitarian needs. The manufacture of chemicals from petroleum and natural gas constituents is an excellent example of the conversion of such materials to more valuable products. The individual chemicals made from petroleum and natural gas numerous and include industrial chemicals, household chemicals and paints, as well as intermediates for the manufacture of products, such as synthetic rubber and plastics. The processing of petroleum hydrocarbon to yield materials that are, essentially, the building blocks of other chemicals industries, is now very extensive. The classification of materials such as petrochemicals is used to indicate the source of the chemical compounds, but it should be remembered that many common petrochemicals can be made form other sources, and the terminology is therefore a matter of source identification., Petrochemicals are generally chemical compounds derived from petroleum either by direct manufacture or by indirect manufacture as by-products from the variety of processes that are used during the refining of petroleum. Gasoline, fuel oils, lubricating oils, waxes, asphalts, and the like are excluded from the definition of petrochemicals, since they are not, in the true sense, chemical compounds but are in fact intimate mixtures of hydrocarbons. B级 The chemical industry depends very heavily on petroleum and natural gas as sources of raw materials. It is likely that in excess of 80% of the literally thousands of different basic organic chemicals employed today are derived from these sources. The petrochemical industry has grown with the petroleum industry. As is the case with the latest trends in changing crude oil types, it must also evolve to meet changing technological and humanitarian needs. The manufacture of chemicals from petroleum and natural gas constituents is an excellent example of the conversion of such materials to more valuable products. The individual chemicals made from petroleum and natural gas numerous and include industrial chemicals, household chemicals and paints, as well as intermediates for the manufacture of products, such as synthetic rubber and plastics. The processing of petroleum hydrocarbon to yield materials that are, essentially, the building blocks of other chemicals industries, is now very extensive.