The oils or products of the last running accumulate at the base of the column, and are carried off to their special refrigerator _Q_. The alcoholic vapors concentrate while rising in the column and quickly attain a strength of 92∞ or 94∞ F. At a height within the column corresponding to the plates whereon alcohol of that strength is to be found, there are provided three taps _u_ whereby the middle runnings or medium grade of alcohol may be drawn off, which have a maximum concentration of 92∞ and 94∞ F. Above these middle plates the alcohol vapors are completely separated from the products of the "tail" that is the aldehydes, amylic oils, etc., and at the upper portion of the column there is found the condenser _K_ which separates the products of the head; that is the first runnings from the alcohol which has passed over with such products to the condenser. The alcohol so separated is completely rectified in the column of final purification _D_ and the finished alcohol is cooled in the refrigerator _O_ below the column of final condensation. In this apparatus the gauge glasses which regulate the exit of the various alcohols and mixtures are controlled by taps having verniers or scales whereby they may be very carefully adjusted, to regulate the relative proportion of the various products. This apparatus is able to produce about 75 or 80 per cent. of first-class alcohol, 10 to 15 per cent. of middle class alcohol, and 5 per cent. of ethers and 5 per cent. of fusel oils, the alcohol produced being about 96∞ Cartier. The alcohol is thus obtained in one single operation and with, it is asserted, only a very small loss in rectification. The apparatus is claimed to be so simple that it may be operated even by unskilled farm labor. It is also claimed that purification by chemical treatment or filtration is unnecessary with the Guillaume apparatus. It may be stated, however, that the Guillaume system has many opponents. The capacity of the rectifying apparatus has a good deal of influence upon both the quantity and the quality of the spirit obtained. Besides being much more difficult to manage, a small apparatus will not yield so large a proportion of spirit as a more capacious one, nor will its products be of equally good flavor. The proportion of alcohol which may be obtained from a successful rectification is very variable; it depends upon the nature of the spirit rectified, the method of extracting the sugar, and the manner of conducting the distillation; it will also be in inverse proportion to the quantity of fusel-oil contained in the raw spirit. The average loss of pure alcohol during the process of rectification is generally estimated at about five per cent.