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 



S /O 



ftME //V MtNUTES 



BO 



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 contact} 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 



