coal gas, gas obtained in the destructive distillation of soft coal, as a byproduct in the preparation of coke. Its composition varies, but in general it is made up largely of hydrogen and methane with small amounts of other hydrocarbons, carbon monoxide (a poisonous gas), carbon dioxide, and nitrogen. It is used as a fuel and illuminant.
"coal gas." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (November 18, 2018). https://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/coal-gas
"coal gas." The Columbia Encyclopedia, 6th ed.. . Retrieved November 18, 2018 from Encyclopedia.com: https://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/coal-gas