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CHARCOAL

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Originally appearing in Volume V05, Page 856 of the 1911 Encyclopedia Britannica.
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CHARCOAL , the blackish See also:

residue consisting of impure See also:carbon obtained by removing the volatile constituents of See also:animal and See also:vegetable substances; See also:wood gives origin to wood-charcoal; See also:sugar to sugar-charcoal; See also:bone to bone-charcoal (which, however, mainly consists of See also:calcium phosphate); while See also:coal gives " See also:coke " and " See also:gas-carbon." The first See also:part of the word charcoal is of obscure origin. The See also:independent use of " See also:char," meaning to scorch, to reduce to carbon, is comparatively See also:recent, and must have been taken from " charcoal," which is quite See also:early. The New See also:English See also:Dictionary gives as the earliest instance of " char " a See also:quotation dated 1679. Similarly the word " chark " or" chak," meaning the same as " char," is also See also:late, and is probably due to a wrong See also:division of the word " charcoal," or, as it was often spelled in the 16th and 17th centuries, " charkole " and " charkecoal." No suggestions for an origin of " char " are satisfactory. It may be a use of the word " chare," which appears in " char-woman," the See also:American " chore "; in all these words it means " turn," a turn of See also:work, a See also:job, and " charcoal " would have to mean " turned coal," i.e. wood changed or turned to coal, a somewhat forced derivation, for which there is no authority. Another See also:suggestion is that it is connected with " chirk " or "See also:shark," an old word meaning " to make a grating See also:noise." Wood-charcoal.—In districts where there is an abundance of wood, as in the forests of See also:France, See also:Austria and See also:Sweden, the operation of charcoal-burning is of the crudest description. The method, which See also:dates back to a very remote See also:period, generally consists in piling billets of wood on their ends so as to See also:form a conical See also:pile, openings being See also:left at the bottom to admit See also:air, with a central See also:shaft to serve as a flue. The whole is covered with See also:turf of moistened See also:soil. The firing is begun at the bottom of the flue, and gradually spreads outwards and upwards. The success of the operation—both as to the See also:intrinsic value of the product andits amount—depends upon the See also:rate of the See also:combustion. Under See also:average conditions, Too parts of wood yield about 6o parts by See also:volume, or 25 parts by See also:weight, of charcoal. The See also:modern See also:process of carbonizing wood—either in small pieces or as sawdust—in See also:cast See also:iron retorts is extensively practised where wood is scarce, and also by See also:reason of the recovery of valuable by-products (wood. spirit, pyroligneous See also:acid, wood-See also:tar), which the process permits.

The question of the temperature of the carbonization is important; according to J. See also:

Percy, wood becomes See also:brown at 220° C., a deep brown-See also:black after some See also:time at 28o°, and an easily powdered See also:mass at 310°. Charcoal made at 300° is brown, soft and friable, and readily inflames at 38o'; made at higher temperatures it is hard and brittle, and does not See also:fire until heated to about 700°. One of the most important applications of wood-charcoal is as a constituent of See also:gunpowder (q.v.). It is also used in metallurgical operations as a reducing See also:agent, but its application has been diminished by the introduction of coke, See also:anthracite smalls, &c. A limited quantity is made up into the form of See also:drawing crayons; but the greatest amount is used as a See also:fuel. The porosity of wood-charcoal explains why it floats on the See also:surface of See also:water, although it is actually denser, its specific gravity being about 1.5. The porosity, also explains the See also:property of absorbing gases and vapours; at See also:ordinary temperatures See also:ammonia and See also:cyanogen are most readily taken up; and See also:Sir See also:James See also:Dewar has utilized this property for the preparation of high vacua at See also:low temperatures. This See also:character is commercially applied in the use of wood-charcoal as a disinfectant. The fetid gases produced by the putrefaction and See also:waste of organic See also:matter enter into the pores of the charcoal, and there meet with the See also:oxygen previously absorbed from the See also:atmosphere; oxidation ensues, and the noxious effluvia are decomposed. Generally, however, the See also:action is a purely See also:mechanical one, the gases being only absorbed. Its pharmacological action depends on the same property; it absorbs the gases of the See also:stomach and intestines (hence its use in cases of flatulence), and also liquids and solids.

Wood-charcoal has also the See also:

power of removing colouring matters from solutions, but this property is possessed in a much higher degree by animal-charcoal. Animal-charcoal or bone black is the carbonaceous residue obtained by the dry See also:distillation of bones; it contains only about To% of carbon, the See also:remainder being calcium and See also:magnesium See also:phosphates (8o%) and other inorganic material originally See also:present in the bones. It is generally manufactured from the residues obtained in the See also:glue (q.v.) and See also:gelatin (q.v.) See also:industries. Its decolorizing power was applied in 1812 by Derosne to the clarification of the syrups obtained in sugar-refining; but its use in this direction has now greatly diminished, owing to the introduction of more active and easily managed reagents. It is still used to some extent in laboratory practice. The decolorizing power is not permanent, becoming lost after using for some time; it may be revived, however, by washing and reheating. Lampblack or See also:soot is the See also:familiar product of the incomplete combustion of See also:oils, See also:pitch, resins, See also:tallow, &c. It is generally prepared by burning pitch residues (see COAL-TAR) and condensing the product. Thus obtained it is always oily, and, before using as a pigment, it must be purified by ignition in closed crucibles (see CARBON).

End of Article: CHARCOAL

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