Charcoal is a light, black residue, consisting of
carbon and any remaining
ash, obtained by removing water and other volatile constituents from
animal and
vegetation substances. Charcoal is usually produced by slow
pyrolysis, the heating of
wood or other substances in the absence of
oxygen (see
char and
biochar). It is usually an impure form of carbon as it contains ash; however,
sugar charcoal is among the purest forms of carbon readily available, particularly if it is not made by heating but by a
dehydration reaction with
sulfuric acid to minimise the introduction of new impurities, as impurities can be removed from the sugar in advance. The resulting soft, brittle, lightweight, black, porous material resembles
coal.
