J 
THE CLARIFICATION OF FRUIT JUICES. iN) 
plate-and-frame filter presses handle such filtration problems suc- 
cessfully, but the cost of such equipment limits its use to commercial- 
size installations. A pulp filter operated by a steam suction pump 
failed to give satisfactory results. When first started, such a filter 
permits the passage of particles of earth; by the time this ceases the 
surface of the pulp has become coated with a slimy, almost imper- 
vious layer, and filtration becomes extremely slow. Increasing the 
suction upon the filter merely hastens clogging by making this slimy 
layer more compact. Attempts to use a small multiple-disk pulp 
filter fed by gravity were equally unsuccessful; clogging and stop- 
page occurr ed: very quickly under gravity pressures ranging from one- 
fourth to two atmospheres. The difficulty with such filters is two- 
fold. The filtering medium is not sufficiently close in texture to re- 
tain the finer particles until it has become reinforced by a layer of 
earth. As the earth settles out of the undisturbed liquid, the larger 
and heavier particles come down first, followed by the deposition of 
successive strata of finer and finer particles. Such a layer of earth is 
a highly efficient filtering medium in so far as preventing the passage 
of suspended material is concerned, but its working period is short, 
for the reason that there is soon built up on the surface a layer of 
eummy, viscous material which practically stops the flow and necessi- 
tates cleaning and repacking the filter. No satisfactory method of 
overcoming this twofold difficulty in the use of pulp filters either of 
the gravity or of the suction type has been found. 
SIMPLE AND EFFECTIVE METHODS OF FILTRATION WITH 
DIATOMACEOUS EARTH. 
SMALL MULTIPLE-DISK FILTER. 
As a plate-and-frame type of filter press was not available in the 
laboratory, a small multiple-disk pulp filter was so modified as to 
make it essentially a plate-and-frame filter. The circular pulp disks 
were replaced by filter cloths of a closely woven, rather light denim, 
fastened in place at the outer edge and around the central opening 
by rubber gaskets. When all were in place the press was closed and 
water was passed through to wet the cloths thoroughly. A quantity 
of earth sufficient to coat the cloths to a depth of about 0.5 cm. was 
then thoroughly stirred into water and passed into the press. As the 
filter was of the vertical type in which the disks rest one upon another 
like a pile of coins, it was easy to effect uniform distribution of the 
earth over the cloths by running it in while in suspension in water 
under a head of 6 to 10 feet. Water was then passed in until earth 
ceased to wash through. The juice to be filtered was then stirred 
thoroughly with Bee oaccons earth at the rate of two-thirds to 1 
ounce per gallon (4 to 6 pounds per hundred gallons) and passed into 
