By the first of these methods the potatoes are disintegrated in such an apparatus as the Bohn steamer described on page 118. A mixture is made of one-third potatoes, two-thirds water, and onetenth part of sulphuric acid. The mixture is steamed for six or eight hours under pressure. The mash is then cooled and the acid neutralized by milk of lime. It is then fermented. By the second and preferable method, dry or wet potato starch is used, which is malted, and the saccharine solution fermented with yeast. The proportions and method for a vat of say 800 gallons capacity are as follows: Two hundred and sixty-five gallons of water are mixed with 1100 lbs. of dry or 1650 lbs. of moist starch. This mixture is well agitated, and 450 gallons of boiling water run in, together with 165 lbs. of malt. The whole is then stirred energetically and left to saccharify for three or four hours. The saccharine solution thus formed must be brought to 6∞ or 7∞ Baume, at a temperature of from 71∞ to 75∞ F. To this is then added 1-1/100 lbs. of dry yeast for every 220 gallons of "must." Fermentation is soon established and usually occupies about 36 hours. After remaining at rest for 24 hours the "must" is distilled. From each 220 lbs. of starch there should be a yield of about nine gallons of alcohol, at 90∞ F. The fermentation of the potato mash is carried on as described in Chapter II. For the preparation of malt see Chapter VI. CHAPTER VIII. ALCOHOL FROM GRAIN--CORN, WHEAT, RICE, AND OTHER CEREALS. The different cereals constitute a very important source of alcohol in all countries, particularly of course for use in the manufacture of whiskey and gin. All cereals contain an abundance of starchy substance which under the influence of diastase,--that is, malt,--is converted into fermentible sugar. The quantity of sugar and hence the yield of alcohol differs widely. The following table shows the results obtainable by good workmanship. 220 lbs. Wheat gives 7.0 gallons pure alcohol " " Rye " 6.16 " " " " " Barley " 5.5 " " " " " Oats " 4.8 " " " " " Buckwheat " 5.5 " " " " " Corn (Indian) " 5.5 " " " " " Rice " 7.7 " " " In addition to these there are other raw materials containing starch which are sometimes used, as millet (55 per cent starch), chestnuts (28 per cent.), and horse chestnuts (40 per cent.). The last is very difficult to work however.