THE CLARIFICATION OF FRUIT JUICES. 19 
with the material accumulated by scraping the filter, are preserved 
and burned for subsequent use. 
It will be seen from the foregoing description that this arrange- 
ment gives essentially the advantages obtained by the use of molded 
silica filtering plates, with the differences that the material used is 
inexpensive and may be used over and over again practically without 
loss; that there is no danger from breakage, as in the case of filter 
plates; that cleaning and replacement are matters of a few minutes’ 
work only; and that the filtering disks may be made of any size or 
shape desired by the individual operator, who may readily make 
one or more filters of any desired capacity to suit his reeds. 
A FILTER FOR HOUSEHOLD USE, 
For handling small quantities of juice, such as would be put up 
for individual household use, where a suction pump is not available, 
very satisfactory results are obtained by gravity filtration through 
a disk of earth. The vessel used should be a deep one, in order that 
the column of liquid upon the filter may be heavy enough to aid 
filtration; for this reason also the vessel should be kept full while 
filtration is going on. A cask provided with a false bottom for sup- 
porting the filter and a faucet placed just below it for drawing off 
the juice serves very well. The filter disk should be made somewhat 
thicker than would be the case in a filter operated by suction and 
greater care must be employed to pack the earth firmly over the whole 
surface and especially along the walls of the container. Caution 
must be employed in filling the filter for the first time, in order not 
to wash holes in the layer of earth; it is well to place a wooden float 
in the vessel and to pour the juice upon it, as the disk of a gravity 
filter, unlike that of a suction filter, becomes less rather than more 
compact in use. For this reason there is less choking, and a gravity 
filter under a head of 2 feet of liquid will run at a practically uni- 
form rate for a long period, as there is much less tendency to form 
a compact slime layer over the surface than when suction is used. 
A FILTER OF THE JELLY-BAG TYPE. 
A device of the jelly-bag type permits quite satisfactory filtration 
of small quantities which would not justify the making of a more 
elaborate filter. The bag should be made of heavy closely woven 
denim and should have the form of a rather tall cone. The seam 
should be double and should preferably be made by machine in 
order to guard against leakage. After wetting the bag thoroughly, 
it should be suspended and such a quantity of earth, previously made 
into a thin paste with water, poured into it as will practically fill it. 
After the water has drained away the treatment should be repeated, 
