ClIA 



CHA 



escape through it ; a small flue or 

 channel for air may also be left along 

 the ground, under the wood, on the 

 windward side, and passing to the 

 central chimney : this is the simplest 

 construction. Sometimes a pit or 

 walled space is used, in which tiie 

 wood is laid, flues being sunk to con- 

 vey air to the bottom, and a central 

 chimney left, the top being covered 

 with earth, ashes, or cinders. The 

 kiln is fired by placing in the central 

 chimney leaves, straw, or twigs well 

 lighted, and allowing the draught to 

 remain open until the upper logs of 

 wood are well fired, afterward closing 

 the under flue. As soon as the flame 

 dies away, the wood being red-hot 

 above, close the top of the chimney 

 and let the fire smoulder. It requires 

 from six to ten days to burn a kiln, 

 and constant attention must be paid. 

 Hard wood requires most time. The 

 average yield is 16 per cent, of coal, 

 but hard woods, well burned, some- 

 times furnish 25. Box, lignum vitae, | 

 mahogany, chestnut, and oak yield 

 most. In this process, nearly all the , 

 carbon of the wood is left, the oxygen 

 and hydrogen uniting in combustion 

 to form water, and the object in view 

 is to keep out atmospheric air, which 

 would cause the combustion of the 

 carbon also. 



Properties. — Charcoal possesses 

 many remarkable properties. 1st. It 

 has the power ofremoving fetid smells 

 from water, meats, and manures ; 

 hence it is used in disinfecting priv- 

 ies and manures. 2d. It removes the 

 colour of many fluids, and is used in 

 clarifying juices and solutions, espe- 

 cially in refining sugar. 3d. It is re- 

 markably porous, and absorbs from 

 the air and other media, gases : 1 

 cubic inch of fresh box-wood was 

 found by Saussure to absorb and con- 

 dense 90 of ammoniacal gas, 35 of car- 

 bonic acid, 9i of oxygen, and 7^ of 

 nitrogen ; this property gives it great 

 value in putrescent composts, and as 

 a manure. 4th. Charcoal is nearly 

 unchangeable in common air at the 

 ordinary temperature, but burns, 

 when heated to redness, into carbon- 

 ic acid, if abundance of air be present. 



144 



5th. Being a very bad conductor of 

 heat, it is used to line refrigerators 

 and small ice-houses. 



As a Manure. — Charcoal, in small 

 lumps or coarse powder, has been 

 highly recommended of late as a top 

 dressing. About 40 bushels the acre, 

 over grass lands, or among young 

 plants, as turnips, has been known 

 to produce a heavy increase. Its 

 success will, however, depend upon 

 the goodness of the soil, and its 

 wants. Wherever an increased sup- 

 ply of ammonia from the air is want- 

 ing, the charcoal does good. The 

 fresh -burned article also contains 

 much saline matter, soluble in water. 

 The best, and perhaps only advisable 

 way of using it, is to compost the pow- 

 der with night soil, urine, blood, and 

 other putrescent bodies ; it tends to 

 dry up the fluids, and retains the am- 

 monia formed during their decay. 

 Such composts added to the soil, re- 

 tain their virtue much longer than 

 the bodies when used alone. The 

 charcoal yields to roots of plants the 

 gases it has absorbed. But it has 

 been shown by numerous gardeners 

 that charcoal powder, kept moist with 

 rain water, is a good soil for many 

 flowers, and capable of sustaining 

 vigorous vegetation, and that slips 

 take root readily in it. Besides its 

 absorbent action, charcoal will loosen 

 tough soils and increase their warmth 

 by its black colour : it adds to the 

 tilth by giving greater porousness. 



Great dijictdty has been found in 

 obtaining powdered charcoal ; this 

 is readily obviated by crushing the 

 lumps in a rough bark mill, which 

 every farmer can set up with an old 

 stone, turning around a post and 

 pressing on a few flag-stones. See 

 Mill. 



CHARCOAL, ANIMAL. BONE 

 BLACK, IVORY BLACK. These 

 terms are used chiefly to indicate 

 bones charred by heat. It is prepa- 

 red extensively for sugar refiners, be- 

 ing much more valuable in remo- 

 ving colours than common charcoal. 

 Sometimes it is made by placing 

 bones in an open iron vessel and 

 heating until they are sufficiently 



