CHARCOAL

The fixed residuum of vegetables exposed to ignition out of contact of air. In the article Carbon , I have described the general properties of charcoal and the simplest mode of making it. I shall here detail the best systems of manufacturing this product upon the continent of Europe. IMG:4147767755307473660_illo0276a.png:Charcoal Meiler To carbonize wood under a movable covering, the plan of meiler , or heaps, is employed very much in Germany. The wood is arranged either in horizontal layers, or in nearly vertical ones, with a slight slope, so as to form conical rounded heaps of different sizes. The former are called lying meiler , fig. 272. ; the latter standing meiler , figs. 273. and 274. Both are distributed in much the same way. IMG:4147767755307473660_illo0276b.png:Tar catcher In districts where the wood can be transported into one place by means of rivers, or mountain slides, a dry flat space must be pitched upon, screened from storms and floods, which may be walled round, having a slight declivity made in the ground, towards the centre. See fig. 275. Into this space the tarry acid will partially fall, and may be conducted outwards, through a covered gutter beneath, into a covered tank. The mouth of the tank must be shut, during the coaking, with an iron or stone slab, luted with clay. A square iron plate is placed over the inner orifice of the gutter, to prevent it being choked with coal ashes. Fig. 275. represents a walled meiler station; a , the station; b , the gutter; c , the tank, which is covered with the slab d ; e , a slab which serves to keep the gutter clear of coals. The cover of the heaps is formed of earth, sand, ashes, or such other matter as may be most readily found in the woods. They should be kindled in the centre. From 6 days to 4 weeks may be required for charring a heap, according to its size; hard wood requiring most time; and the slower the proce , the better and greater is the product, generally speaking. IMG:4147767755307473660_illo0276c.png:Charcoal mound Charring of wood in mounds ( Haufe or liegende werke ) figs. 276. and 277. differs from that in the meiler , because the wood in the haufe is succe ively charred, and the charcoal is raked out by little and little. The product is said to be greater in this way, and also better. Uncleft billets, 6 or 8 feet long, being laid over each other, are covered with ashes, and then carbonized. The station is sometimes horizontal, and sometimes made to slope. The length may be 24 feet, the breadth 8 feet; and the wood is laid cro wise. Piles are set perpendicularly to support the roof, made of boughs and leaves, covered with ashes. Pipes are occasionally laid within the upper part of the mounds, which serve to catch and carry off some of the liquid products into proper tanks. IMG:4147767755307473660_illo0277a.png:Chabau iere Fig. 278. is a vertical section, and fig. 279. a half bird’s-eye view, and half cro section, at the height of the pit-bottom, of Chabeau ière’s kiln for making wood charcoal. a is the oven; b , vertical air-pipes; c c , horizontal flues for admitting air to the kiln; d d , small pits which communicate by short horizontal pipes e e , with the vertical ones; f , the sole of the kiln, a circle of brickwork, upon which the cover or hood h reposes; i , a pipe which leads to the cistern k ; l , the pipe destined for carrying off the gaseous matter; m m , holes in the iron cover or lid. The distribution of the wood is like that in the horizontal meilers , or heaps; it is kindled in the central vertical canal with burning fuel, and the lid is covered with a few inches of earth. At the beginning of the operation all the draught flues are left open, but they are progre ively closed, as occasion requires. In eight kilns of this kind, 500 dec asters of oak wood are carbonized, from which 16,000 hectolitres of charcoal are obtained, equal to 64,000 pounds French, being about 25 per cent.; besides tar and 3000 velts of wood vinegar, of from 2° to 3°. Baumé . IMG:4147767755307473660_illo0277b.png:Turf-charcoal kiln At Crouy upon the Ourcq, near Meaux, there is a well constructed kiln for making turf-charcoal. It resembles most nearly a tar-kiln. In fig. 280. a is the cylindrical coaking place, whose surrounding walls are heated by the flame which pa es through the intermediate space b . The place itself is divided by partitions of fire tiles into three stages, through the apertures in which the flames of the fire c c , rise, and heat the exterior of the coaking apartment. In order to confine the heat, there is in the enclosing walls of the outer kiln a cylindrical hollow space d , where the air is kept stagnant. Through the apertures left in the upper end at e , the turf is introduced; they are then shut with an iron plate f , which is covered with ashes or sand. The fire-place opens above this aperture, and its outlet is provided with a moveable iron cover g , in which there is a small hole for the i ue of the gases. The sole of the kiln consists of a cast iron slab h , which may be raised by means of a hook i upon it. This is drawn back after the carbonization is completed, whereby the charcoal falls from the coaking space into a subjacent vault. The volatile products are carried off by the pipe k , and led into the condensing cistern; the gases escaping to the fire-place where they are burned. The iron slab is protected from the corrosion of the acid vapours by a layer of coal ashes. CHICA is a red colouring principle made use of in America by some Indian tribes to stain their skins. It is extracted from the bignonia chica by boiling its leaves in water, decanting the decoction, and allowing it to settle and cool, when a red matter falls down, which is formed into cakes and dried. This substance is not fusible, and, when burned, diffuses the same odour as animal bodies do. It is insoluble in cold water, very soluble in alcohol and ether, but, after the evaporation of these liquids, it is recovered unchanged. Fats and unctuous oils both di olve it. It is soluble in carbonated and caustic alkaline lyes, from which it is precipitated by the acids without alteration. An exce of alkali, however, speedily decomposes it. Nitric acid transforms it into oxalic acid, and a bitter matter. Chlorine makes it white. The savages mix this pigment with the fat of the cayman or alligator, and rub their skins with the mixture. It may probably be turned to account in the arts of civilized nations.