FERMENTATION 



577 



and from every 100 tons of sugar made, from 3,000 to 9,000 gallons of 

 molasses result, dependent, of course, on the composition of the juice. Given 

 100 tons of sugar per week, from 3,000 to 9,000 gallons of wash per day will 

 be produced, and, allowing the fermentation to take 48 hours, the capacity 

 of the vats must be double this. In practice it would be advisable to allow 

 at least 25 per cent, in excess of the calculated figure. Of course, in many 

 places a longer period than 48 hours is taken in the fermentation, and then a 

 corresponding increase in the capacity of the vats must be allowed. A usual 

 size of vat found in the West Indies is one holding about 3,000 gallons. In 

 Scotch and English distilleries much larger vats are the rule and a capacity 

 of 50,000 gallons is not unusual. The initial cost of erecting a few large vats, 

 and a loft to contain them and cost of upkeep, is less than for a larger number 



FIG. 356 



of small vats, and it is a general opinion that a slightly better fei mentation 

 is obtained in larger vats. 



Antiseptics should find a larger use in distilleries, especially when shut 

 down ; all gutters, pipes, &c., should be carefully cleansed. The antiseptic 

 most in use in Europe now is a I per cent, solution of ammonium fluoride. 



Forms of Stills. The stills used may be divided into two classes, direct 

 fired and steam stills ; or again into intermittent or continuous stills. Direct 

 fired stills are very uncommon and only a few remain in unprogressive 

 districts. They are constructed of copper and set in brickwork over a furnace 

 with a circular flue. Besides being expensive as regards first cost, they are 

 very uneconomical in fuel consumption. 



Vat Still. A sectional view of the general form of steam-heated vat still 

 is given in Fig. 356; a is a wooden vat of capacity varying with the amount 

 of wash to be treated ; at d is shown the pipe through which the lees are 



