Test Glass for the High-Grade Alcohol.
Y Test Glass for First Runnings. Y' Test Glass for Last Runnings. Z Test Glass for Determining Degree of Exhaustion of Spent Wash.
In this apparatus the still proper is of the form heretofore described on page 78. The liquid to be distilled enters at the top of the inclined column A and descends to the base thereof. The alcoholic vapor rises through the column and passes off from the head thereof into the rectifying column. At the head of the column A it has a strength of 40 to 50 per cent. The column C is supported upon aft accumulating reservoir V which acts to regulate the flow of the phlegm through the rectifying column and prevents too great an exhaustion of the plates of the column. It acts as a reservoir to contain any excess of phlegm or to supply an additional amount of phlegm to the plates when they have become nearly exhausted.
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 to 94%. 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 concentra-
tion of 92 to 94 per cent. 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 per cent.
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.
In addition to the rectifying as above described, alcohol may be further purified by filtration through charcoal, by chemical means or by electrolysis. The last two methods have not so far been successful. The chemicals used merely act to disguise the disagreeable taste or smell of the spirit and do not really purify. They but substitute one impurity for another. The agents used are many—sulphuric and nitrate acids, soaps, oils and fats soda, lime and potash have each and all been tried, but with no permanent success. As agents for disguising the taste of new and raw spirits, alcoholic extracts of fruits have also been used.
Purification and aging by electricity has been tried many times and in many different forms, but so far has not been commercially practicable.
Filtration still remains the best and simplest adjunct to the rectifier. In small plants, a filter bed several feet in thickness of bone black or beachwood or charcoal is used, laid upon a foundation of gravel in a filtering tank. In the larger plants a series of these vats is used, the charcoal being used in lumps varying from % to / inch in diameter. Two different views of the purification by charcoal are held—one that the charcoal purifies by chemical means, the other that it is purely a physical filtration agent. After filtration the charcoal must be steamed to recover the spirits retained therein and should be heated to a red heat every now and then to cleanse and regenerate it.
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