ACETIC ACID.— Wood Carbonizers.

17

perature reaching ebullition. Part of the distilledvapours and gases, in their progress downwards,condense into a liquid, which falls into the air-tights, and is thence conveyed by the connecting pipe,T into another tank, collaterally placed, but at alower level, v is a tube from the pipe G, projectinginto the furnace, through which the uncondensedcarbonaceous gases flow into the fire, where theyare utilized as fuel. When the distillation has fairly

Fig. 11.

commenced, these gases serve to maintain almost

sufficient heat to effect the decomposition of thecharge.

lhe usual time allowed for carbonizing each chargeis twenty-four hours. After the wood is exhausted,the fire is withdrawn from the oven for six hours, so

that the apparatus may cool, to allow the charcoal to, e abstracted through the opening at the back, air-t ght sheet-iron boxes being placed beneath the doorto receive it—100 cubic feet of beechwood produce*0 Per cent, of charcoal, as much brushwood beingused to obtain the heat required to carbonize the wood.

lhe apparatus in use at Nuits and Rouen , int' ranee, is the followingIn Fig. 12 A is a largeVOL. i.

sheet-iron cylinder with an opening in the upperpart of one of the sides, into which an adapter, B,is introduced; c is the cover of the cylinder, fittedtightly to it with bolts and screws. The cylinderbeing charged with wood, the cover, C, is fixedtightly in its place, and the cylinder hoisted bymeans of a crane, d, fixed adjacent to the furnace,and deposited in an upright cylinder of brickworkwhich may be covered, at will, by means of a dome,E, made of brickwork. The cylinder is charged withwood and deposited in its receptacle, and the fire isthen lighted. The tube, C, through which the distilledproducts pass off to the condenser, is next connectedto the cylinder by means of the adapter, B, thejoint being well luted. The condenser is similar tothat attached to the oven at Fig. 11, and consists ofa series of pipes, I, I, I, through which C passes.Water from the pipe, L, enters the pipes, i, i, i, bymeans of f and the connecting pipes, t., t,, near thecurvature, the heated water being discharged bythe pipe, o. The condensed products pass off intothe covered receiver. The uncondensed gases areconducted through the pipe, P, back to the furnace,where they are consumed. The pipe, P, terminatesin a rose, N, similar to that of a watering can, a fewinches above the floor of the ashpit. The gasesare by this means regularly distributed through thefire. M is a stopcock, by which the quantity of gasentering the furnace is controlled.

In some factories different methods of condensingthe products are adopted. In a few instances coldair instead of water is the medium by which thevapours are condensed. The evolved products ofthe distillation are in this case caused to traverse anextensive range of piping of large diameter, or areconducted through a series of casks which have beenconnected together by pipes. Water is, however, byfar the most effectual mode of condensation, and istherefore generally employed. About twenty-fourhours are usually allowed to work off each batch ofwood.

Schwartz' carbonizer is shown in Figs. 13, 14,and 15. Fig. 13 is a bird-eye view of the furnace,Fig. 14 a section of the elevation following the linesd d, and Fig. 15 another section, following the linesC C. In each of these figures similar letters areused to distinguish the same objects. A A is thespace where the wood is carbonized; b b b b arethe apertures through which the wood is introducedand the charcoal afterwards is withdrawn; C C arethe fires which heat the furnace ; d <7, the openingsthrough which the acetic acid and tlic smoke, carbonicacid, oleaginous, tarry matters, &c., pass off throughthe pipes, g g, and tlienee through the condenserinto the chimney ; c e are crooked pipes descendingfrom g g, which convey the tar condensed in g intothe vessels, ff (Fig. 14) ; the bend in the pipes, e c,is made in order to prevent access of air into theapparatus ; II n n it are wooden canals, wherein theacetic acid and volatile oils condense; I is the chim-ney, and k a small opening in the chimney, in whicha fire is occasionally lighted to establish a draught.The furnace walls are of fire-brick, or they may be

3