Charcoal is a term applied to an impure variety of carbon, especially such as is produced by charring wood. One kind of charcoal is also obtained from bones. Lampblack and coke are also varieties.
Wood charcoal is inannfactured by the partial combustion of wood piled in heaps, with air-spaces between, and covered with turf. Water and various combustible materials are driven off, and impure carbon retaining the original structure of the wood is left. The more modern method is to heat the wood in closed retorts, when, in addition to the charcoal which is left behind, various volatile products of importance are obtained; among these are a combustible gas, wood spirit, pyroligneous acid, and wood tar.
Wood charcoal, well prepared, is of a deep-black colour, brittle and porous, tasteless and inodorous. It is combustible at high temperatures, cannot be fused in any flame or furnace, but is volatilized at the high temperature of the electric arc, presenting a surface with a distinct appearance of having undergone fusion. Charcoal is insoluble in water, and is not affected by it at low temperatures; hence, wooden stakes which are to be immersed in water are often charred to preserve them, and the ends of posts stuck in the ground are also thus treated. Owing to its peculiarly porous texture, charcoal possesses the property of absorbing considerable volumes of air or other gases at common temperatures, and of yielding the greater part of them when heated.
Charcoal likewise absorbs the odoriferous and colouring principles of most animal and vegetable substances, and hence is a valuable deodorizer, disinfectant, and decoloriser. Formerly, water which, from having been long kept in wooden vessels, as during long voyages, had acquired an offensive smell, was deprived of it by nitration through charcoal powder. Charcoal can also prevent the decay of animal and vegetable matter.
Charcoal is used as a smokeless fuel in stoves, etc, as a reducing agent in metallurgical operations, e.g. for obtaining metals from their oxides, and for converting wrought iron into steel by the process of cementation. It is an important component of ordinary gunpowder, and is used in domestic filters. In its finer state of aggregation, under the form of ivory-black, lampblack, etc, charcoal is the basis of black paint; and mixed with fat oils and resinous matter,to give a due consistence, it constitutes printing-ink. Artist's charcoal is formed from sticks of willow wood. Research Charcoal
Abbreviations
SciTech
Research Charcoal