6 BULLETIN 921, TJ. S. DEPARTMENT OF AGEICULTUEE. 
DISCUSSION OF RESULTS. 
These results show that raw cane juice, without the addition 
of lime, sulphur dioxid, or other chemicals, can be rapidly filtered in 
an ordinary plate and frame filter press when sufficient infusorial 
earth of a good grade is added to the heated juice. It is very desir- 
able, however, that the infusorial earth be of very low specific 
gravity and also of fine mesh. The best results were obtained with 
commercial grades of infusorial earth obtained from California, 
Oregon, and Washington. It is also desirable that the infusorial 
earth be dry and free from lumps and trash. For successful filtration 
the infusorial earth must be mixed thoroughly with the juice. If it 
is wet and lumpy it does not mix well, and if it is trashy there is 
always trouble with the pump valves becoming clogged. However, 
with a good, clean, dry grade of infusorial earth, such as is at present 
on the market, no trouble whatever was experienced in obtaining a 
steady filtration, a firm press cake with each frame entirely filled, 
and a filtered liquor bright and clear. 
Most of these experiments were made by adding a weighed quan- 
tity of infusorial earth to 200 gallons of juice. Based upon a 78 
per cent extraction obtained by the mill, a dilution of approximately 
14 per cent, and the average final Brix of the dilute juice, which was 
13°, this volume of juice is almost exactly the amount obtained from 
1 ton of cane. With- a good quality of infusorial earth 10 pounds to 
the ton of cane gave a satisfactory filtration. "With less than this 
amount the filtration was slow and there was danger of a slimy, 
almost impervious, coating forming on the cloths which would retard 
the rate of filtration. 
With 10 pounds of infusorial earth per ton, 1,200 gallons of juice, 
or that from 6 tons of cane, could be put through the 18-inch 18- 
f rame filter press in about three and one-half hours. Using 12 pounds 
of this earth to 1 ton of cane, a much more rapid filtration resulted, 
the juice from 5 to 5 J tons of cane filtering in two to three hours. 
With 11 pounds of high-grade infusorial earth per ton, satisfactory 
results were also obtained, the juice from 5 to 6 tons of cane filtering 
in about four hours. No trouble at all was experienced in obtaining a 
steady, clear filtration and a firm press cake. It is not well, however, 
to try to put through the press a larger quantity of juice than will 
filter readily under moderate pressure. In the press available for 
these experiments, using 11 pounds of infusorial earth per ton of 
cane, it was found best not to try to force through more than the 
amount of juice from 5-J tons of cane. This amount, filtered in about 
four hours with a pressure not exceeding 40 to 50 pounds, made a 
hard and firm cake throughout the entire frame. This press cake 
could be washed easily and thoroughly and peeled readily from the 
