Charcoal

Charcoal, form of amorphous carbon produced when wood, peat, bones, cellulose, or other carbonaceous substances are heated with little or no air present. A highly porous residue of microcrystalline graphite remains. Charcoal as a fuel was used in blast furnaces until the advent of coke. A highly porous form, activated charcoal, is used for adsorption in refining processes and in gas masks.

See also: Carbon.