THE CLARIFICATION OF FRUIT JUICES. 13 
of wax varying between 5 and 50 per cent by weight,* the relation 
of certain commercially employed upper Miocene deposits of diato- 
maceous earth to oil fields (7, 2), and the character of the flavor im- 
parted to juices indicated that the material might be a derivative 
of wax. This assumption was borne out by its behavior, but no 
attempt to isolate the material in quantity or to study it chemically 
was made. Attention was directed to the working out of simple 
methods for removing it with sufficient completeness to make the 
earth free from discoverable effect upon the flavor of the juices. 
PURIFICATION OF THE EARTH. 
Extraction of the earth with the usual fat solvents completely re- 
moved the material which gives foreign flavor to juices, but such 
treatment on other than an experimental scale is impracticable. <At- 
tempts to wash out the contaminating material in the manner recom- 
mended by some filter-press manufacturers, by stirring the earth 
into boiling water, decanting after settling, and repeating the process 
a few times, proved ineffective, as earth so treated still had percep- 
tible effect upon the flavor of delicate juices after 10 or 12 changes 
of water. Earth boiled on a water bath for several days with re- 
peated changes of water was not wholly freed of the contaminating 
material. 
The most satisfactory method of purifying the earth was by in- 
cineration. In preliminary work small lots were placed in porcelain 
dishes, heated to low redness for 30 minutes in an electric furnace, 
allowed to cool, and rubbed through a sieve having 50 to 80 meshes 
per inch. For the preparation of larger lots a metal container made 
by capping one end of a 4-inch iron pipe 20 inches long and provid- 
ing a loosely fitting plug for the opposite end was used. This was 
filled with the earth, plugged, placed in the fire box of a steam boiler, 
and allowed to remain for an hour. An ordinary heavy-walled steel 
kettle provided with a lid has also been used with satisfactory results. 
The traces of iron thus added to the earth are without discoverable 
effect upon the juices. 
Purification by heating has the obvious advantage that it permits 
repeated use of the earth. On burning a quantity of earth which 
has become loaded with material] derived from the juice an insignifi- 
cant amount of ash remains in the earth, but this does not materially 
increase with repeated use. Carbon progressively accumulates with . 
repeated burnings, ultimately becoming sufficient to exert an appre- 
ciable decolorizing effect upon juices filtered through it. In prac- 
tice it has been found possible to use a single lot of earth 10 to 15 
times, revivifying by burning after each use, before the carbon 
3Mann, Albert. Personal communication to the writer. 
