Coal oil

Coal oil is a shale oil obtained from the destructive distillation of cannel coal, mineral wax, or bituminous shale, once used widely for illumination.

Chemically similar to the more refined, petroleum-derived kerosene, it consists mainly of several hydrocarbons of the alkane series, with 10 to 16 carbon atoms in each molecule and a higher boiling point (175–325 °C) than gasoline or the petroleum ethers and lower than the oils.

The term was in use by the late 18th century, for oil produced as a byproduct of the production of coal gas and coal tar. In the early 19th century it was discovered that coal oil distilled from cannel coal could be used in lamps as an illuminant, although the early coal oil burned with a smokey flame, so that it was used only for outdoor lamps; cleaner-burning whale oil was used in indoor lamps.

Coal oil that burned cleanly enough to compete with whale oil as an indoor illuminant was first produced in 1850 by James Young on the Union Canal in Scotland, who patented the process. Production thrived in Scotland, creating much wealth for Young.

In the United States, coal oil was widely manufactured in the 1850s under the trade name Kerosene, manufactured by a process invented by Canadian geologist Abraham Gesner. Young triumphed in his patent lawsuit against the Gesner process in the United States in 1860. But by that time, US coal oil distillers were switching over to refining cheaper petroleum, after the discovery of abundant petroleum in western Pennsylvania in 1859, and oil from coal operations ceased in the US.

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