20 



* 



tightly the press may be closed. The alcohol soon evaporates from the 

 cloth and leaves the latter sticky with sugar solution. It would proba- 

 bly be easy to arrange a metal cover for the press which would prevent 

 or diminish this loss. An arrangement should also be provided to 

 avoid the exposure of the alcohol sirup to the open air and thus prevent 

 the evaporation of the alcohol. In the ordinary press the alcohol must 

 fall through a space of 2 feet or more before reaching the trough. This 

 loss can not occur in a press arranged as shown in the accompanying 

 sketch (Fig. 3). In this press the filtered sirup passes into a channel 

 (7, and from there through a pipe line to the receiving tank. The cocks 

 A and B are so arranged that one can draw a test sample either from 

 the channel or the filter plate. The channel E is for dilute alcohol and 

 D the sirup alcohol mixture. The pipe line for filtered sirup should 

 be provided with sight glasses in order to promptly detect the flow of 

 turbid sirup. As soon as the flow of turbid sirup is detected, the open- 

 ing into the channel at the proper place should be closed. From time 

 to time the sirup from the closed plate should be examined, since ordi- 

 narily after a short time it will flow clear. 



It is probable that filter bags could be employed with economy in the 

 filtration of these sirups. If so, the cost of the filtering plant would 

 be materially reduced. By means of the improved apparatus sug- 

 gested, the sirup-alcohol mixture would be out of contact with the air 

 at all times and the loss of alcohol from evaporation would be reduced 

 to a minimum. 



The loss of alcohol (calculated as absolute) in the filter-press cake 

 ranged from 3.7 per cent to 15.9 per cent of the weight of the press 

 cake, or to an approximate average of 3.5 pounds per ton of clean cane, 

 or to .5 gallon 90 per cent (by weight) alcohol. This loss would be con- 

 siderably smaller in working on a large scale, since then there would 

 always be sufficient material to produce a firm, hard press cake con- 

 taining a high proportion of solid matters. 



Press- cakes have been obtained containing as high as 70 per cent of 

 solid matter. 



The press employed was not provided with a channel for use in dis- 

 placing the sirup left in the press cake. Such a provision would enable 

 the removal of practically all of the sirup-alcohol mixture from the 

 press-cake, leaving dilute alcohol in its place, thus reducing the amount 

 of sugar and alcohol in this by-product. 



Becommendations in regard to the utilization of the press cakes in 

 the manufacture of alcohol are made in another part of this report. 



PLAN OF EXPERIMENTS. 



The experiments were conducted with a view to the direct comparison 

 of the ordinary and the alcohol processes. It was expected in this way 

 to emphasize the practical difficulties or advantages of either process. 



