CHARCOAL. 



CHARCOAL. 



putrefaction. He found the odour of succinic 

 and benzoic acids, of bugs, of empyreumatic 

 oils, of infusions of valerian, essence of 

 wormwood, spirits distilled from bad grain, 

 and sulphureous substances were all absorb- ' 

 able by freshly calcined charcoal properly 

 applied. A very ingenious filter has been 

 constructed for purifying water, by passing it 

 through strata of charcoal of different fineness. 



When charcoal is burned, one-third of the 

 heat is discharged by radiation, and two-thirds 

 by conduction. 



The following table of the quantity of char- 

 coal yielded by different woods was published 

 by Mr. Mushet, as the result of experiments 

 carefully made upon the small scale. He says, 

 the woods before being charred were tho- 

 roughly dried, and pieces of each kind were 

 selected as nearly alike in every respect as 

 possible. One hundred parts of each sort 

 were taken, and they produced as under : 



Lignum Vitae afforded 26-0 of charcoal of a grayish co- 

 lour, resembling coke. 



Mahogany - - 25'4 tinged with brown, spongy 

 and porous. 



Laburnum - - 2-1-5 velvet black, compact, very 

 hard. 



Chestnut - - 23 2 glossy black, compact, firm. 



Oak - 22-6 black, close, very fir'm. 



Walnut - - - 206 dull black, close," firm. 



Holly ... 19 9 dull black, loose and bulky. 



Beech ... 19'9 dull black, spongy, firm. 



Sycamore - - 197 fine black, bulky, moderately 

 firm. 



Elm ... 19-5 fine black, moderately firm. 



Norway Pine - - 19'2 shining black, bulky, very 

 soft. 



Sallow or willow - 18'4 velvet black, bulky, loose, 

 and soft. 



Ash ... 17'9 shining black, spongy, firm. 



Birch - - - 17-4 velvet black, bulky/firm. 



Scotish Pine - - 16'4 tinged with brown, mode- 

 rately firm. 



Messrs. Allen and Pepys, from 100 parts of 

 the following woods, obtained the quantities 

 of charcoal as under : 



Beech - 15-00 



Mahogany - 15'75 

 Lignum Vitffi - 17'25 



Oak - 

 Fir - 

 Box - 



- 17-40 



- 18-17 



- 20-25 



It is observable that the quantities obtained 

 by Messrs. Allen and Pepys are in general less 

 than those given by Mr. Mushet, which may 

 be owing to Mr. Mushet not having applied 

 sufficient heat, or operated long enough, to dis- 

 sipate the aqueous matter of the gaseous pro- 

 ducts. 



To those persons who buy charcoal by 

 weight, it is important to purchase it as soon 

 after it is made as possible, as it quickly ab- 

 sorbs a considerable portion of water from the 

 atmosphere. Different woods, however, differ 

 in this respect. Messrs. Allen and Pepys 

 found, that by a week's exposure to the air, the 

 charcoal of 



Lignum Vitae gained - 



Fir - 



Box .... 



Beech - 

 Oak - 



Mahosany - 



- 9-6 per cent. 



- 13-0 ditto. 



- 14-0 ditto. 



- 16-3 ditto. 



- 16-5 ditto. 



- 180 ditto. 



The following is a tabular view of the vo- 

 lumes of the different gases which were ab- 

 ^sorbed in the course of twenty-four hours, by 

 lone volume of charcoal, in the experiments of 

 M.Theodore de Saussure, which were conduct- 

 ed in a way likely to produce correct results. 

 312 



Each portion of charcoal was heated afresh to 

 a red heat, and allowed to cool under mercury. 

 When taken from the mercury, it was instantly 

 plunged into the vessel of gas: 



Ammoniacal gas - 90 i Bicnrbureted hydrogen 85 00 

 Muriatic acid gas - 85 j Carbonic oxyde /- 9'42 

 Sulphurous acid - 65 I Oxygen gas - - 925 

 Sulphureted hydrogen 55 Nitrogen - 7'.M) 



Nitrous oxyde - 40 Carbureted hydrogen 5'00 



Carbonic acid gas - 35 Hydrogen gas - - 1-75 



(C/re's Diet, of Arts.} 



In England charcoal is prepared in two dif- 

 ferent ways. In one, billets of wood are formed 

 into a heap, which is covered with turf, and a 

 few small openings only left for the admission 

 of the air requisite to maintain it in a state of 

 low combustion after it is lighted. When the 

 whole heap is on fire, the holes are stopped ; 

 and, after the mass has cooled, the residue is 

 charcoal. In the other mode the wood is 

 distilled in iron cylinders, in which case the 

 products are pyroligneous acids, and empy- 

 reumatic oil; and what remains in the retort 

 is charcoal. The quantity of the distilled pro- 

 ducts, as well as of the charcoal, depends on 

 the kind of wood employed. 100 parts of dried 

 oak yields, of 



PaiU. 



Pyroligneous acid - - - - - 43- 



Carbonate of potassa - - - 4'5 



Empyreumatic oil ----- 9 06 



Charcoal ------- 26-2 



The charcoal thus procured is lighter than 

 common charcoal. Charcoal should be black, 

 sonorous, brittle, and retain the texture of the 

 wood. It has a powerful attraction for water, 

 gases, and odorous and colouring principles. 

 It is a powerful antiseptic, and well adapted 

 for preserving animal substances from putre- 

 faction. In fine powder it is much used as a 

 tooth-powder, for which purpose, however, it 

 is exceptionable, since, being insoluble, it gets 

 between the teeth and gums and thus leads to 

 their separation and much mischief. 



Ivory, or bone black, is animal charcoal, 

 prepared in the same manner as the second 

 kind of vegetable charcoal. It has a remarka- 

 ble property of abstracting colour from many 

 vegetable solutions, on which account it is 

 much used by sugar refiners. 



"Plants," says Liebig, "thrive in powdered 

 charcoal, and may be brought to blossom and 

 bear fruit, if exposed to the influence of the 

 rain and the atmosphere ; the charcoal may 

 be previously heated to redness. Charcoal 

 is the most unchangeable substance known; 

 it may be kept for centuries without change, 

 and is therefore not subject to decomposition. 

 The only substances which it can yield to 

 plants are some salts which it contains, 

 amongst which is silicate of potash. It .is 

 known, however, to possess the power of 

 condensing gases within its pores, and parti- 

 cularly carbonic acid. And it is by virtue of 

 this power that the roots of plants are supplied 

 in charcoal exactly as in humus, with an at- 

 mosphere of carbonic acid and air, which is 

 renewed as quickly as it is abstracted. 



" In charcoal powder, which had been used 



for this purpose by Lukas for several years, 



| Huchver found a brown substance soluble in 



I alkalies. This substance was evidently due 



