Petroleum is a thick, dark liquid composed mostly of compoundscalled hydrocarbons that contain carbon and hydrogen.` Natural gas usually associated with petroleum deposits consists9.7 Present Sources of Energy, usually associated with petroleum deposits, consistsmostly of methane but also contains significant amounts of ethane,propane, and butane.` As gasoline became more important, new ways were sought toincrease the yield of gasoline obtained from each barrel ofpetroleum.Zumdahl/Decoste | Chemical Principles, 8e, © 2017 Cengage Learning` William Burton invented a process at Standard Oil of Indianacalled pyrolytic (high-temperature) cracking. In this process theheavier molecules of the kerosene fraction are heated to about700 C, causing them to break (crack) into the smaller molecules ofhydrocarbons in the gasoline fraction