STILL.

245

chests is nearly on a level with the ground, so that the bars do not need to be liftedhigh in charging the furnace. The flame rises between the two chests, passes alsobelow and round them through horizontal and vertical flues, d, and issues from. thefurnace by an opening, H, in the top of the vault, and by orifices, t, which communicatewith the chimneys placed in the angles. The whole is placed within a large cone ofbricks, 25 or 30 feet high, and open at top; this cone increases the draught, makes itmore regular, and carries off the smoke away from the establishment. The furnacehas three doors; two, t (fig. 162), above the chests, serve to admit and to remove thebars ; they are about 7 or 8 inches square ; in each of them a piece of sheet-iron is put,folded back on its edges; upon which the bars are made to slide, so as to save thewall. A workman enters by the middle door, p, to arrange the bars; the trial barsare taken out from time to time by the apertures, s (fig. 161), left in the sides of thechests. The bars are laid in strata, along with wood charcoal in powder, in the saidchests; they are about 3 inches broad, and one third of an inch thick; they mustnot be placed too near each other, lest they should get welded together; the last oruppermost layer is covered with a stratum of loamy matter from 4 to 5 inches thick.The furnace must be gradually heated, not reaching its maximum temperature before8 or 9 days, and the cooling lasts 5 or 6 days; the whole operation 18 or 20 days, andsometimes more, according to the quality of the steel to be cemented. About 13 tonsof coals are consumed ill this period. It is of consequence that the refrigeration beslow, to favor the crystallization of the metal. The grain of the steel varies with therate of cooling, the largest and whitest grain denoting the most fusible steel.

STILL. The continuous system of distillation has been carried in France to a greatpitch of perfection, by the ingenuity chiefly of M. Cellier Blumenthal, and M. Ch.Derosne. Fig. 164 is a general view of their apparatus ; A and b are boilers or alembics

encased in brickwork, and re-ceiving directly the action ofthe flame playing beneaththem; in the copper, A, thevinasse, or spent wine, is finallyexhausted of all its alcohol,c, is the column of distillation;D, the column of rectification;

e, the wine-heating condenser;r, the refrigerator; g, a vesselsupplying vinasse to the cooler

f, and feeding itself at the sametime by means of a ball stop-cock placed in the vessel h;h, reservoir of vinasse; i, tubeof communication conductingthe alcoholic vapors of therectifying column, d, up intothe flat worm of the wine-heater, e; a, stop-cock of dis-charge of the alembic, A; whenthe operation goes on, thespent vinasse runs o/I' con-tinually by this stop-cock;b, a glass tube to show theheight of the liquor in A; c, asafety-valve; d, a stop-cockfor passing the vinasse fromthe alembic, b, into the bottomof the alembic, a ; e, a tubeto lead the alcoholic vapors,generated in a, into the bottomof b, which vapors, in passingthrough the liquor in b, heat it,and are partially condensed;/, glass tube to mark the levelof the liquor in b ; g, and g, levelindicators; h, pipe conducting

the vinasse from the lower part of the wine-heater, e, upon the uppermost of the seriesof horizontal discs, mounted within the column of distillation : i, a stop-cock for empty-ing the wine-heater at the end of an operation; l, l, two tubes fitted to the wine-heater,e, of which the first descends into the last compartment of the rectifier, whence it rises