Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood, sugar, bone char, or other substances in the absence of oxygen (see pyrolysis, char and biochar). The resulting soft, brittle, lightweight, black, porous material resembles coal and is 85% to 98% carbon with the remainder consisting of volatile chemicals and ash. The first part of the word is of obscure origin, but the first use of the term coal in English was as a reference to charcoal. In this compound term, the prefix chare- meant turn, with the literal meaning being to turn to coal. The independent use of char, meaning to scorch, to reduce to carbon, is comparatively recent and is assumed to be a back-formation from the earlier charcoal. It may be a use of the word charren or churn, meaning to turn; i.e. wood changed or turned to coal, or it may be from the French charbon. A person who manufactured charcoal was formerly known as a collier (also as a wood collier). The word collier was also used for those who mined or dealt in coal, and for the ships that transported it. Charcoal, or biochar, is also an essential element in the composition of terra preta.
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