388 On the Stale of the Manufacture of Sugar in France. 
these graters consist of cylinders furnished on the surface with 
indented plates; these cylinders may be moved so rapidly, by 
means of wheels, that they will make 400 revolutions in a mi- 
nute, and will tear and reduce the beet to a pulp in an instant. 
Two of these graters, put in motion by the same machinery, and 
attended by three women and two children, are sufficient to 
grate daily 10,000 weight of beet, by working only four hours 
a-day, two hours at atime; it is very rare that half an hour 
more is necessary. 
Immediately as the operation of grating is terminated, the 
persons employed begin to cleanse the graters, to wash them, 
and then to place round them the 5000 weight of beet that are to 
be grated at the second operation. 
Tn order that the pulp may be of a good quality, it must have 
the appearance of a soft paste, without any lumps; for the press, 
however powerful, can extract but a very small proportion of 
juice from fragments of beet that have not been torn. When it 
is only crushed between mill-stones, in the manner that is prac- 
tised for making cider and perry, the juice obtained from the 
press is not more than 39 or 40 per cent., whereas when it is 
torn by the graters, from 65 to 75 per cent. is extracted. 2dly, 
As fast as the pulp is formed it is submitted to pressure, in or- 
der to extract the juice. I begin by putting it into small lever 
presses at first, and afterwards removing it to others more power- 
’ tul, so as to extract from 65 to 75 per cent. of juice. The 
operation is perfect when the marc or dregs are so dry that on 
squeezing it hard with the hands it does not wet them. ‘To di- 
minish the expense of manual labour, I place the graters and 
“presses on a Stage, in such a manner that the juice falls of itself, 
through leaden canals, into the boilers, which are placed on the 
ground. It is necessary that the pulp should be expressed as 
fast as it forms, or else it blackens, and a degree of fermentation 
commences, which renders the extraction of the sugar more dif- 
ficult. The juice marks from five to eleven degrees, and com- 
monly from seven to eight by Baumé’s areometer. 
Four men are sufficient to work the presses, in operating upon 
ten thousand weight of beet per day. 
I have before mentioned, that the juices run immediately out 
of the preascs into a boiler, which I call a depurator, in relation 
to its use. Supposing two operations to be effected in a day, 
and that 5000 weight of beet-root is operated upon each time, 
this boiler, which is round, should be five feet and a half wide, 
and three feet eight inches deep; of these dimensions it will 
contain the whole product of one operation. As soon as the 
boiler is one-third or half full, the fire is lighted. By the time. 
that. 
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