264 The Sugar-Beet in America 
reason, evaporation is carried on under reduced pres- 
sure which lowers the boiling point of the liquid. After 
the juice is reduced from about 82 per cent of water to 
about 40 per cent, it is again treated with sulfur and 
filtered in a manner similar to that used for the “thin 
juice.” This is the final process of purifying the beet 
juice, which is then ready for graining. 
In refining cane-sugar, there is no treatment with sulfur ; 
impurities are removed with bone black. This is the 
chief difference in the method of making sugar from cane 
and from beets in the United States. In Europe, where 
raw beet-sugar is produced by many factories, this prod- 
uct also is refined by the aid of bone black. In early 
days blood was used extensively in sugar refining, but this 
practice has now been discontinued entirely. 
GRAINING 
The vacuum-pan serves not only for evaporating the 
sirup but also for crystallizing the sugar. This pan is a 
large cast-iron tank in which the air pressure can be kept 
low to reduce the danger of browning the sugar by high 
heat. If the juice has been purified properly, there is no 
trouble about producing good sugar in this pan; but if 
impurities remain, it is difficult to obtain good crystal- 
lization. This mixture of crystals and sirup is called 
“ massecuite.” It is run through a centrifugal machine, 
like that shown in Plate XXIX, revolving at a rate of 1200 
revolutions a minute. The sirup is thrown out through 
fine perforations in the wall of the machine, and the 
crystals of sugar remain, dropping out through the bottom 
