When the wash above alluded to is ad justed as to density, it is run into the fermenting vats, where, mixed with a small quantity of yeast, it is subjected to the process of fermentation, which con tinues from six to ten or twelve days, the time required for its completion vary ing with the mass of liquid and with the temperature of the atmosphere.
During mashing, as well as during fer mentation, the starch passes into sugar, and the sugar into alcohol ; the conse quence of which is that the wash gradu ally decreases in density or attenuates ; and as soon as this attenuation has reach ed its maximum, which may be deter mined by the hydrometer, it should be distilled, in order to prevent the access of acetous fermentation.
In all large distilleries there are two sets of stills : one for the purpose of dis tilling from the wash a weak spirit, tech nically called low wines ; and the other for redistilling (or rectifying) the low wines. In these distillations there passes over along with the first and last portions of the spirits a peculiar volatile oil of a disagreeable flavor and odor, and render ing the weaker spirit milky. These por tions are called faints, and are carefully turned into separate receivers as soon as the appearance of the runnings from the worm-end indicates their presence.
The quantity of alcohol which may be obtained from a given quantity of sugar will depend upon the skill and care with which mashing, fermentation, and distil lation have been respectively conducted ; theoretically, 100 pounds of sugar are convertible into about 51 of alcohol and 49 of carbonic acid. The quantity of al cohol to be procured from different kinds of grain will also depend upon the same causes, and upon the quantity of sugar, and of starch and gum convertible into sugar, which each may contain.
Sometimes malt only is used ih the dis tillery, in which ease the distiller calcu lates in obtaining two gallons of whiskey of proof strength from each bushel of malt. In some distilleries as much as 3000 gallons per day are produced, and the worm of the still is passed into the body of a second still, so that the heat arising from the condensation in the worm raises the temperature in the second still, and thus economises fuel.
There is a kind of ardent spirits man ufactured in Holland, vulgarly called Dutch gin, Hollands, and sometimes genes, from genievre, the French for juniper, a plant with the essential oil of whose berries it is flavored. One cwt. of ground malt mixed with two ewts. of rye meal are mashed for two hours, with about 450 gallons of water at the temper ature of 160° F. The mash drawn off is reduced with cold water till the liquid part has the density of 45 lbs. per barrel, = specific gravity 1.047; and is then put altogether into the fermenting back at the temperature of 80° F. One or two gallons of yeast are added. The fermen tation soon becomes so vigorous as to raise the heat to 90° and upwards, but it is not pushed far, being generally over in two days, when the gravity of the wash still indicates 12 lbs. of saccharurn per barrel. By this moderate attenua tion, like that practised by the contra band distillers of the Highlands of Scot land, it is supposed that the fetid oil of the husks is not evolved, or at least in very small quantity. The grains are put into the alembic along with the liquid wash; and distilled into low wines, which are rectified twice over, some juniper ber ries and hops being added at the last dis tillation. But the junipers are some times bruised and put Into the mash. The produce of worts so imperfectly fer mented, is probably little more than one half of what the British distiller draws from the same quantity of grain. But the cheapness of labor and of grain, as well as the superior flavor of the Skis dam spirits, enables the Dutch distiller to carry on his business with a respecta ble profit. In opposition to the above facts, Dubrunfaut says that about one third more spirits are _obtained in Hol land from grain than in France, because a very calcareous spring water is em ployea in the mashing operation. Were this account well founded, all that the dis tillers of other countries would have to do would be merely to introduce a portion of chalk into their mash tubs, in order to be on a par with the Dutch. But the statement is altogether a mistake.