By their arrangement, which is shown in the opposite figure, they form a mechanical system permitting of the rectification of alcohols at temperatures as low as -40° or even -50°. They verify experimentally, by their operation, the theoretical deductions which precede. The boilers, A, which, in an industrial application, may be more numerous, receive their supply of spirits from the country distilleries in the vicinity of the factory. There may even be introduced directly into them _vinasses_, or washes, that is to say, liquids, such as are obtained by alcoholic fermentation. Above the boiler rises a rectifying column composed of superposed plates inclined one over the other, and surmounted by a tubular condenser, which serves to effect the retrogression of the first condensation by means of a current of water supplied by the reservoir placed above. On leaving this condenser, the vapors which have escaped condensation pass into the refrigerator, C, where they are totally condensed by a current of water which goes to the reservoir above. The first products obtained contain ethers and impure alcohols, which are collected in the reservoir, E. When the first products have been thus introduced into the reservoir, and it is ascertained by tasting that good alcohol is passing over, the liquid produced is directed into the second boiler, F. The sliding valve, operated by a screw having a very fine pitch, establishes a communication between the refrigerator, C, and the second boiler, F. The office of this valve we shall learn further on. This first rectification is performed in a vacuum, for a system of metallic pipes connects the entire apparatus with an air-pump, O. The temperature at which the liquids shall enter into ebullition in the boilers, A A, may, then, be regulated in advance. The operations will be carried on with a more or less complete vacuum, according to the nature of the products to be rectified. The distiller will have to be guided in this by practice alone. The good tasted products are received in boiler No. 2, F, and there the liquids are submitted to the action of an almost absolute vacuum. As we have before said, their temperature falls immediately and spontaneously. The vapors which issue from this liquid contain almost solely pure alcohol. The other substances, which passed over in the first distillation, no longer emit vapors at temperatures ranging between -10° and +5°. Their temperature is shown by a thermometer running into the boiler, F.