16 BULLETIN 1025, U. S. DEPARTMENT OF AGRICULTURE. 
the filter from a feed tank with a gravity head of 10 to 12 feet. The 
juice in the feed tank was vigorously stirred from time to time to 
maintain a uniform suspension and prevent the clogging of the feed 
line. The filtrate was clear and brilliant; filtration was quite rapid 
and was maintained at an almost uniform rate until the press had be- 
come completely filled with quite compact cakes. As the filter was 
not so constructed as to permit thorough cleaning by back flushing, 
it was necessary to open the press to clean it, but the cakes could 
be turned off the cloths practically entire, the cloths washed and 
replaced, and the press made ready for a second run in considerably 
less time than was required to clean and repack the same press with 
filter pulp. 
SUGGESTIONS FOR THE MANUFACTURE OF A SMALL FILTER. 
If the makers of filtering equipment would devote some attention — 
to the manufacture of filtering devices suited to use with diatomace- 
ous earth which would nave the efficiency of some of the small labora- 
tory filters now made for experimental use, placing them on the 
market in a range of sizes and at prices which would put them within 
feach of fruit growers and small operators who make a few hun- 
dred to a few thousand gallons of cider or grape juice annually, they 
should find a very considerable market. Such filters might be of any 
one of several types. A wooden plate-and-frame press to be fed either 
by a pump or under a gravity pressure of 12 to 15 pounds, so con- - 
structed as to permit cleaning by back flushing, should give satis- 
factory results. The vertical multiple-disk filter, consisting of a 
series of superposed metal plates each carrying a disk of filter pulp, 
if modified so as to permit the substitution for pulp of readily at- 
tached filter cloths and to provide for the removal of the cake by back 
flushing with water, should also be efficient, as the vertical position 
ot the filter areas facilitates deposition of a uniform film of earth 
over them and secures uniform cakes free from channels. A further 
advantageous modification of this type would be the deepening of 
the chambers so as to give space for thicker cakes. Such a filter 
might be operated either by gravity or by a pump. 
The leaf filter has a number of features which lend themselves 
very advantageously to the filtration of fruit juices and which make ~ 
it possible to construct inexpensive filters of small capacity. The 
leaf type of construction makes it possible to obtain a large filtering 
area in a small apparatus, while the fact that filtration is from with- 
out inward permits the quick cleaning of the filter cloths as they 
become clogged without removing them from the frames. Such a 
filter might be made up in units of two or more leaves, to be installed 
by the user in any suitable tank and operated either by suction or 
by gravity, at very moderate cost. 
