16 



THE VACUUM STILL. 



The vacuum still, which it is proposed to use for the separation of the 

 alcohol from the sirup in place of the apparatus just described, is illus- 

 trated in Fig. 2. This illustration simply gives an idea of what such a 

 still should be without any attempt at making it technically perfect. 



The object, as indicated, is to separate the alcohol from the sirup at 

 a low temperature, by means of a jet of exhaust steam, in such a way 

 as to secure a minimum dilution of the sirup and the complete separa- 

 tion of the alcohol. The alcohol separated in this way would be of 

 low strength, probably not much above proof spirit, but the sirup 

 would emerge from the still without ever having reached the tempera- 

 ture of boiling water and without any danger of scorching. 



Two methods of procedure may be employed. If it is desired to 

 secure the alcohol in a form ready for subsequent condensation the com- 

 plete apparatus described can be used. If, on the other hand, it is 

 desired to save the heat which would be lost in the condensation of the 

 alcoholic vapors, the vacuum part of the still, that is, the part used for 

 the separation, could be connected directly at the top and to one side 

 with the condensing still. In this process the condensing still would 

 have to operate under a vacuum, and the vacuum apparatus would be 

 simply transferred from the end of the still indicated to the end of the 

 vacuum still. The condensing, or alcohol still, would be placed above 

 and to one side of the beer still, and be provided with a separate scroll 

 or steam jet. Inasmuch, however, as the specific heat of alcohol vapor 

 is somewhat low there would not be a very great loss of heat in con- 

 densing the alcohol in the first place, as indicated, and subjecting the 

 alcohol thus obtained to subsequent distillation. 



The still consists of a beer column B of ordinary construction. It is 

 furnished at V with a vacuum gauge and at T with a thermometer. 

 The exhaust steam is admitted through a pipe S and escapes through 

 the rose R immediately under the first chamber. The chambers of the 

 beer still are separated by perforated diaphragms and connected one 

 with the other with overflow tubes and cups in the usual manner. 

 The sirup enters the still in its upper chamber through the heater JJ, 

 and can be supplied either by a feed pump or from a tank placed higher 

 than H. The supply from the tank would be more easily regulated and 

 would be preferred. 



The sirup, after it has passed through the still and is freed from alco- 

 hol, descends through the tail pipe P to the sirup tank A opening un- 

 derneath the level of the sirup in the tank so as to be completely sealed, 

 as indicated. The length of the tail pipe P is sufficient to produce a 

 free exit of sirup under the vacuum employed. The sirup in tank A, after 

 it has filled the tank to the required level, escapes constantly through 

 the pipe C to the sirup pump. At the end of the operation the sirup 

 remaining in A can be withdrawn by opening the cock w the pipe JE^ 



