THE PREPARATION OF CORN OIL. 9 
that some vegetable oils will lighten in color on heating, but indi- 
vidual oils differ in this respect. Corn oil does not appear to bleach 
to a sufficient extent under this treatment alone. 
The third experiment was designed to show the influence of the 
period of contact of the earth with the oil on the bleaching effected 
7 ~e/*pe#a rc/*E /oo * c 
77a*£ 
o 
/minute 
/OM Mures 
ZOMMUT&S 
36. 
23. S 
/3.0 
/3.0 
/?ED 
AS 
/./ 
ASS 
/.60 
s /o 
T/ME //V M/NUTES 
Fig. 4.— Relation between the time of contact with the fuller's earth and the bleaching effected. 
Six per cent of standard fuller's earth was used at a temperature of 
100° C. for periods' of 1, 5, 10, and 20 minutes, respectively. From 
figure 4 it is evident that the maximum bleaching effect is obtained 
after a 5-minute contactj and that about half of the bleaching is 
accomplished in the first minute. 
Some difference of opinion exists as to whether fuller's earth effects 
a more efficient bleach if previously dehydrated. It is said to be the 
67251°— 22— Bull. 1010 2 
