The oil saturation value of bleaching earths and carbons

Summary

An adaptation of the oil absorption test as applied to paint pigments has been made to serve as a means of readily comparing the oil saturation value of different bleaching earths and chars.

The weight of oil absorbed by 100 grams of earth under specified conditions is roughly proportional to the amounts of oil which will be retained in the usual process of bleaching vegetable oils.

As a rule that fuller’s earth which has the greatest bleaching power will also absorb the most oil but this is by no means always true. Carbons show much higher oil absorption than fuller’s earths and this increase is greater than their increased bleaching affect on cottonseed oils. With the proposed method a chemist in the laboratory may safely predict whether an earth will give high or low losses in the bleach presses of the refinery. He cannot however say what the factory losses will be without first accumulating a lot of comparative data on the same earths tested in the laboratory and as actually used under the particular conditions of his own plant.