





Charcas, 

 Charcoal. 



C H A 



752 





C H A 



*-*v 



afterwards at the beginning of staves where modula- 

 tion has taken place, are fully treated of by Dr Call- 

 cott, in his Musical Grammar, art. 278, &c. () 



CHARCAS. See BUENOS AYRES, p. 51. 



CHARCOAL. This is a well known black sub- 

 stance, which possesses many singular chemical pro- 

 perties, the details of which will be given under the 

 article CHEMISTRY. In the present article we shall 

 confine ourselves to the modes of preparation employ- 

 ed in Britain and in France, and to its economical 

 uses 



Charcoal which is employed as fuel, is obtained 

 generally from wood of different kinds ; the most 

 dense and hard being preferred. The white and 

 resinous woods are commonly rejected. Large tim- 

 ber is seldom employed for this purpose, both because 

 it is too expensive, and because it does not yield 

 charcoal equal in quality to that procured from cop- 

 pice wood. Pieces of three or four inches thick 

 must be cloven into four pieces. 



It is an object of some moment to ascertain the 

 most productive wood in the preparation of charcoal ; 

 and although accurate results are not to be expected 

 on the great scale, yet experiments made by Mr 

 Mushet afford very good general proportions, which 

 may be the rule by which the products may be esti- 

 mated. 



The following Table exhibits very satisfactorily 

 the results of these experiments. 



Colour. 

 1 00 parts of Lignum Vitae afforded 26.8 charcoal, greyish. 



Mahogany 25.4 



Laburnum 24.5 



Chesnut 23.2 



Oak 22 6 



American Black Beech 21.4 



Holly 19.9 



Sycamore 19.7 



Walnut ........ 20.6 



Beech 19.9 



American Maple . . 19.9 



Norway Pine .... 19.2 



Elm 19.5 



Sallow 18.4 



'Ash .' . 17.9 



Birch 17.4 



Scottish Pine .... 16.4 



brown, 

 velvet black, 

 glossy black, 

 black, 

 fine black, 

 dull black, 

 fine black, 

 dull black, 

 dull black, 

 dull black, 

 shining black, 

 fine black, 

 velvet black, 

 shining black, 

 velvet black, 

 brownish. 



In Scotland very large quantities of charcoal are 



prepared for the iron works, in the following way : 



A platform, having a diameter of from twenty to 

 thirty feet, is formed on the ground, by laying strata 

 of earth upon it, and giving it a slightly convex sur- 

 face. On the centre of this circular area, a circle of 

 sticks are so placed as to cross each other a little be- 

 low the top, and thus to form a cavity resembling an 

 inverted cone, around which successive concentric 

 layers of truncheons, having a diameter of from one 

 to ten inches, are placed ; care being taken, that the 

 truncheons in the same circle are of the same size, 

 and as few interstices as possible left. The exterior 

 circle is composed entirely of brushwood. When the 

 platform is nearly covered, a coating of turf is iaid 

 on the pile, the grassy side being next to the wood ; 

 dry earth is then heaped up around the lower part, 

 and well rammed down, so as to exclude all air. The 

 pile is then lighted, by placing a few inflamed chips 

 of wood in the interior cavity ; and when these are 

 consumed, others are added during the first three or 

 four days. When the upper part of the pile is com- 



pletely inflamed, a row of holes, each of which has a Charcoal, 

 diameter of two inches, is made around it at a few "*" "^T*** 

 inches below the top, and the opening at that part is 

 closed up. The flame then gradually descends to the 

 circle of holes, and its arrival there is announced by 

 a very perceptible diminution of smoke and vapour. 

 Another row of air holes is then made at a distance 

 of six or eight inches below the first row, which are 

 closed up, and the same' ope ration is repeated until the 

 flame has been conducted to the lowest part of the 

 pile, which generally happens in about a fortnight } 

 when the whole is carefully covered until the fire is 

 extinguished. Such pieces as are not completely- 

 charred, are separated, and reserved as fuel for the 

 next pile. 



The charcoal produced from the truncheons is laid 

 aside for particular uses ; and that obtained from the 

 brushwood is sold, under the name of small coal, as 

 fuel. 



In France there is some difference in the mode of 

 preparing the charcoal : it therefore is worth while 

 to give an outline of the various processes there 

 adopted. 



The wood is cut down in large faggots, and after 

 having been well dried for some months, it is divided 

 into brushwood, small and large faggots. The last 

 are cut into truncheons of three or four feet in length. 

 The turf is then taken off a square or circular space, 

 having a diameter of about fifteen feet, and the earth 

 beaten until the surface becomes dry and solid. A 

 stake is next fixed in the middle of the area, and some 

 brushwood laid on the surface as a foundation for 

 the remainder. A stratum of truncheons is then 

 laid on the brushwood, and the same alternatives are 

 repeated, until the pile is completed to the height of 

 about six feet in the form of a truncated cone or py- 

 ramid. As soon as this is done, the whole surface of 

 the pile is covered to the thickness of about two 

 inches with dry earth, over which sods are very com- 

 pactly laid, except at the base, where considerable 

 spaces ars left between them. The central stake is 

 now withdrawn, and the cavity is filled with chips, 

 which arc lighted at the top ; the whole of the chips 

 become inflamed, and after a considerable quantity of 

 smoke has been poured out, a light flame rushes 

 from the chimney in the centre of the pile ; the aper- 

 ture of which is immediately closed by laying a piece 

 of turf over it. 



During the next ten or twelve hours, considerable 

 attention is necessary to prevent any mischief result- 

 ing from the sudden disengagement, and consequent 

 combustion of carburetted hydrogen, which take 

 place during that period of the manufacture. The 

 explosion is announced by a rumbling noise, and sel- 

 dom does any other injury than that of throwing off 

 some portion of the covering, and through the open- 

 ing thus formed flame and smoke issue. It is neces- 

 sary to close up all such openings with a few spade- 

 fuls of dry earth. When the smoke decreases, and 

 the explosions have entirely ceased, the interstices be- 

 tween the sods at the lower part of the pile must be 

 closed. At this stage little attention is required, the 

 combustion gradually extends to the surface, and in 

 about thirty or thirty-four hours after the process 

 commenced the whole pile becomes a glowing mass. 

 The wood is thoroughly charred, the whole is cover- 

 ed with dry earth, and in four or five days it may 



IS - 



