CHARCOAL (probably from 111E, •harken. to crackle.. AS. co/rein?). to creak, variant of craci«n, to crack sole, coal: less plausibly from char, turn, from AS. cure, (.cr. keh•. turn + cols, coal I. A black, porous substanee harming with out smoke or flame, and formed by the imperfect combustion of organic matter. either animal or vegetable. Animal charcoal is produ•ed by cal cining the hones and ivory of animals in closed retorts. In this process the charcoal proper, of the earthy and saline portions of the lame, combined with carhop, is left in the retort, While the volatile matter is allowed to escape into another compartm•nt. when• it is distilled. The escaping gas •ontains, among its other components. an oil when in closed •hands•rs. deposits a soot. which is known as bone-block or Ivory-Wail: pigment. (See LAMPBLACK.) Animal eharcoal, or bone blaek, is itself a most useful material in the arts, on account of its power of absorbing color ing matter and odors. It is the best material known for filtering saccharine solutions (see Sui.mtl, and various processes invent ed for revaleining- bone-black after it has been used until no longer effective.
Wood-chareoor ma y he produced either in temporary furnaces formed by simply covering piles of wood with earth or sand, or in permanent furnaces specially des4med for the purpose. If the former method is employed the wood is fired usually at the top. a central space being left
from bottom to top for the progress of the fire. The gases are allowed to psi-aloe through holes left in the top. This method is much less fre quently employed than formerly, as it not only produces an inferior grade of charcoal for manu facturing purposes. though not for fuel. but also involves the loss of the by-products. which escape in the gases and are lost. A charcoal. furnace is usually it dimw-shaped structure with opening- at the top and side for putting in the wood and a pipe or tube near the top for tho escape or the volatile products. The Wood rests on grates. and the quantity of air is regulated by a closely fitting ash-pit door. The wood is fired at the bottom, and when the process of com bustion has suilhdently advanced, the ash-pit awn- is closed. The wand is now slowly car bonized, and the gaseous products escape into another chamber, where they arc treated as de scribed under LANIPISLAcm.
Wood-chareoal has many uses. It is valuable as a fuel, a polish, a filter, an absorbent of gases and aqueous vapors. As it is a non conductor of heat, it is used as a packing, for ice chests; it. is essential in various kinds of eke trical apparatus. and is an ingredient in gun powder and fireworks.