A number of roots and tubers, including beet, potatoes, carrots, turnips, asphodel, madder, and chicory, have been availed of for the manufacture of alcohol, the most important being beets and potatoes.

Beets contain about 10 per cent, of sugar, which can be converted into alcohol in several ways, chiefly: - (1) rasping and pressing the roots and fermenting the expressed juice; (2) macerating in hot water; (3) direct distillation.

(1) The roots are washed, rasped (grated), and pressed, yielding 80 to 85 per cent, of juice; this is heated to about 82}° F. (28° C), and run into fermenting-vats; here it is acidulated with not more than 6 1/4 lb. of sulphuric acid to every 1750 pints of juice, to neutralize the alkaline salts present, and hinder viscous fermentation. Alcoholic fermentation is assisted by the addition of about 1 oz. of yeast previously mixed with a little water to every 100 pints of juice, the external temperature being carefully maintained at 68° F. (20° C). The alcohol produced by this process is the best but dearest, requiring most plant and labour.

(2) In the maceration process, the washed roots are cut into slices, having a width of less than 1/2 in., a thickness of 1/25 in., and a variable length; the slices are covered with boiling waterln a wooden or iron macerator for 1 hour, the water containing 1 lb. sulphuric acid for every 50} lb. of beet. The partially saturated water is next drawn off into a second vat, where more slices are added, and maceration takes place for 1 hour; and Anally into a third likewise, after which it goes to the fer-meoting-vat. In mild weather the juice will be at about the right heat for fermentation, say71 1/2° to 751/14° F. (22° to 24° C), but in very cold weather reheating may be necessary. The fermentation is similar to that of pressed juice, and is usually complete in 24 to 30 hours. The alcohol thus obtained is inferior but much cheaper.

(3) Laplay's method of direct distillation of the roots is not generally employed. Operations are conducted in vats of 100 bushels' capacity, and a charge consists of 2500 lb. of the sliced roots, inclosed in porous bags, and immersed in 440 gal. of acidulated water, with the temperature maintained at about 77° to 80 1/2° F. (25° to 27° C). The addition of a little yeast starts the fermentation, which lasts about 24 hours. Distillation is conducted in a simple apparatus, leaving the slices available as cattle-food.

Potato-spirit is made chiefly in Germany, and its manufacture has now assumed considerable importance. Potatoes contain 16 to 20 per cent, of starch, which is capable of being converted into glucose by the action of sulphuric acid or of malt. Three principal methods of effecting the saccharification are in use: (1) the potatoes are baked, and then crushed into pulp; (2) rasped to bring about the same result; (3) the starch may be extracted and converted into sugar afterwards.

(1) In the first method are several operations, viz. cooking the potatoes; crushing them; converting the starch into sugar by means of malt; and finally, fermentation and distillation. The operation of "cooking " is carried on in a boiler set in brickwork, surmounted by a tun made of oak staves. The bottom of the tun, which must be of solid wood, is perforated with a number of small square holes to give admittance to the steam from below. The potatoes placed in this tun are rapidly cooked by the ascending steam; they are then withdrawn and crushed into a thick pulp between two rollers, commonly made of oak, and placed below the level of the tun. As the potatoes swell considerably during the steaming, the tun should never be completely filled. The pulp is placed in a vat, holding 660 to 880 gal., in which the saccharification takes place. About 25001b. of the crushed potatoes and 175 lb. of broken malt are introduced, and immediately afterwards water is run in at a temperature of about 86° to 104° F. (36° to 40° C), the contents being well stirred with a fork meanwhile. The vat is then carefully closed for 1/2 hour, after which boiling water is added until the ternperature reaches 140° F. (60° C), when the whole is left for 3 or 4 hours.

The process of fermentation is conducted in the same vat. Alternate doses of cold and boiling water are run in upon the mixture, until the quantity is made up to 700 to 770 gal., according to the size of the vat, and so as finally to bring the temperature to 75 1/4° to 78 3/4° F. (24° to 26° C). Liquid brewer's yeast (4 1/2 to 5 1/4 pints) is added, and fermentation speedily sets in. This process complete, the fermented pulp is distilled in the apparatus devised by Cellier-Blumen-thai, for distilling materials of a pasty nature; the product has a very unpleasant odour and flavour.

(2) By rasping the potatoes, the expensive operations of cooking and separating the starch are avoided. In this operation, the washed potatoes are thrown into a rasping machine similar to those employed in sugar manufactories. If 2500 lb. of potatoes be worked at once, the vat has a capacity of 484 to 550 gal., and a perforated false bottom carrying a layer of straw. The charged potatoes are allowed to stand for 1/2 hour in order to get rid of a portion of their water. After this, 219 to 262 gal. of boiling water are ran in, and then 175 lb. of malt are added; the whole is stirred up and left to macerate for three or four hours. This done, the liquid is drawn off from beneath into the fermenting-vat; the pulp is drained for 1/4 hour, and the drainings are added to the liquor previously run off. Boiling water (109 gal.) is run in upon the pulp, which is again stirred up energetically. After remaining some little time, the water is again drawn off, the pulp drained and washed anew with 109 gal. of cold water, with agitation. This is again drawn off, and the whole of the water with the drainings is mixed up in the fermenting vat. Teast (5 lb.) is added, and the contents of the vat are left to ferment.

Only the liquor is fermented by this process, but the spirit yielded is nearly as unpleasant to taste and smell as that obtained by process No. 1.

(3) The only means of obtaining alcohol of good quality from the potato is to extract the starch and convert it into sugar separately. The saccharfincation of the starch is effected either by sulphuric acid or diastase, the latter being decidedly preferable. In a vat of 660 gal. capacity are mixed together 220 gal. of cold water, and 1250 lb. of dry or 1875 lb. of moist starch. The mixture is well agitated, and 247 gal. of boiling water are run in, together with 180 to 200 lb. of malt; the whole is stirred up energetically for 10 minutes, and then left to saccharify for 3 or 4 hours. The saccharine solution obtained must be brought to 6° or 7° B. at a temperature of 71 1/2° to 75 1/4° F. (22° to 24° C), and 17 1/2 oz. of dry yeast are added for every 290 gal. of must. Fermentation is soon established, and occupies usually about 36 hours. After remaining at rest for 24 hours, the must is distilled; 250 lb. of starch ought to yield 8 to 9 gal. of pure alcohol, or 9 to 10 gal. of alcohol at 90°.

The spirit obtained by treating the yam or street potato in a similar manner is said to be far superior to that yielded by the common potato.

According to Erfindungen und Erfah-rungen, chicory seems likely to become of importance as a source of alcohol. The root contains an average of 24 per cent, of substances easily convertible into sugar, and the alcohol obtained by its saccharification, fermentation, and distillation is characterized by a pleasant aromatic flavour and great purity.