MANUAL FOR SUGAR GROWERS. 131 



The presence of a large amount of alcohol arrests 

 the development of the yeast-plant. Hence in the 

 presence of a considerable amount of sugar the fer- 

 mentation comes to an end before all the sugar is 

 converted into alcohol ; it is therefore wasteful to 

 employ solutions which are too concentrated, as this 

 results in loss of sugar. 



When filter-presses are used in the manufacture of 

 sugar there is no waste product to be converted into 

 rum (the name given to the spirit produced from 

 sugar-cane products) save molasses. This is mixed 

 with water in such proportion that the resulting 

 " wash " has a density of about 8° B. The wash is 

 set up to ferment in vats of various sizes, depending 

 on the size of the distillery, 1,000 gallons being a 

 convenient size. Fermentation, as a rule, soon sets 

 in without the addition of any ferment. Bubbles 

 of carbonic-acid gas rise briskly to the surface, the 

 liquid becomes slightly heated, and the density 

 rapidly diminishes, falling to about 1° to 2° B. when 

 the process is completed. This process usually oc- 

 cupies three or four days. This time could doubtless 

 be shortened by adding to the fresh wash a small 

 quantity of yeast or ferment taken from vats in which 

 fermentation was active. It has been already stated 

 that it is necessary that the solution be slightly acid 

 in order that the cane sugar may be converted into 

 glucose. It is usual, therefore, to add a small quan- 

 tity of sulphuric acid to the wash to obtain this 

 necessary condition. It is only necessary to add so 

 much acid as will render the wash very slightly acid 

 to litmus-paper, indicated by turning blue litmus- 



