THE CLARIFICATION OF FRUIT JUICES. 17 
SIMPLE METHODS FOR USE WITHOUT SPECIAL EQUIPMENT. 
In the absence on the market of any suitable small-capacity press 
adapted to the handling of juices with diatomaceous earth, some time 
was devoted to the working out of methods by which the small oper- 
ator without special equipment could avail himself of the advantages 
offered by the use of earth. The purpose in view was to devise an 
arrangement in which filtration would occur through a layer of earth 
which could be kept from clogging. Clogging can be effectively pre: 
vented by keeping the mixture of earth and liquid thoroughly agi- 
tated, thus securing the constant renewal of the filtering surface by 
deposition of the solid particles of earth in mixture with the amor- 
phous suspended material of the juice. Without such provision for 
agitation the larger particles of earth would quickly come down, after 
which clogging by the amorphous shmy matter arrested at the surface 
would soon occur. It was necessary also to make provision for the 
easy and quick cleaning of the filter or the renewal of the filtering 
layer. 
A LABORATORY FILTER, 
A very simple arrangement meeting these requirements and using 
a compact layer of earth as a filtering medium has been in use in this 
laboratory for some time. It yields a permanently clear filtrate at a 
satisfactory rate and is readily cleaned when necessary. In the first 
small filter made for use in the laboratory, a piece of 100-mesh nickel- 
wire gauze was cut to fit as closely as possible into a large Buchner 
funnel. A quantity of diatomaceous earth was made up into a thick 
paste with water, spread upon the gauze in a layer 2 to 3 cm. thick, 
packed under gentle suction, and washed with water until earth 
ceased to come through, care being taken to keep the surface of the 
layer of earth as smooth as possible. Filtration was then begun. The 
juice to be filtered was mixed with diatomaceous earth, stirred thor- 
oughly, and immediately poured on the filter. Care was taken to re- 
peat the stirring of the liquid every time the filter was refilled. When 
the formation of a layer of slime over the surface materially reduces 
the rate of filtration, the filter is allowed to empty itself, a thin film 
of earth carrying with it the gummy deposit is removed with a spatula 
or similar instrument and stored for revivification by burning, and 
filtration is resumed. By making the layer of earth 2 to 3 cm. thick 
at the outset and packing it firmly, this treatment can be repeated al- 
most indefinitely, as the material which causes clogging is practically 
wholly arrested at the surface, penetrating at most only a millimeter 
or two into a properly packed disk. 
