CHARCOAL , the blackish
See also:residue consisting of impure
See also:carbon obtained by removing the volatile constituents of 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 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 early . The New
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 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 France,
See also:Austria and 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 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 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:process of carbonizing wood—either in small pieces or as sawdust—in
See also:cast iron retorts is extensively practised where wood is scarce, and also by reason of the recovery of valuable by-products (wood. spirit, pyroligneous acid, wood-
See also:tar), which the process permits .
The question of the temperature of the carbonization is important; according to J .Percy, wood becomes
See also:brown at 220° C., a deep brown-black after some
See also:time at 28o°, and an easily powdered 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 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 ordinary temperatures
See also:ammonia and cyanogen are most readily taken up; and
See also:Dewar has utilized this property for the preparation of high vacua at low temperatures . This character is commercially applied in the use of wood-charcoal as a disinfectant . The fetid gases produced by the putrefaction and 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 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 stomach and intestines (hence its use in cases of flatulence), and also liquids and solids .
Wood-charcoal has also thepower 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 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 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 soot is the
See also:familiar product of the incomplete combustion of oils, 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) .
JEAN MARTIN CHARCOT (1825-1893)
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