THE PREPARATION OF CORN OIL. 
19 
pounds 9 of corn oil containing 1.76 per cent of free fatty acids, and a 
comparison of these estimates for both methods is presented in 
Table 10. 
TREATMENT WITH CAUSTIC. 
The difference in cost of chemicals and value of oil lost in the two 
methods is 0.064 cent per pound of refined oil in favor of method 2. 
This slightly lower cost of method 2 is due to the lower refining loss 
of. oil and the slightly greater value of the soapstock, although the 
cost of the chemicals is higher than in method 1. 
Since both methods were found to give a good quality of oil and 
since the difference in cost is not considerable, there would appear 
to be little, if any, advantage of one method over the other. As has 
been previously stated, however, method 2 does not require the 
washing of the oil with brine to remove the traces of soap, and this 
is a distinct advantage, especially from the standpoint of the time 
involved. On the other hand, this method calls for special handling 
of the soapstock in order to reduce the refining loss to the figure 
given in Table 10. In this respect method 1 has the advantage. It 
would appear, therefore, that the two methods are practically of 
equal value as to the ease of operation and cost. 
BLEACHING. 
In commercial practice it is generally assumed that the bleaching 
of vegetable oils with fuller's earth results in a loss of oil equivalent 
to 20 per cent of the weight of earth used. On this basis, the cost 
of the bleaching operation on the quantity of oil under discussion as 
regards the cost of earth and the value of the oil lost would be as 
shown in Table 11. 
Table 11. — Cost of material used and, value of the oil lost in bleaching corn oil with 
fuller's earth. 
Items of comparison . 
Weight of oil to be bleached pounds. 
Quantity of fuller's earth required (5 per cent) a do 
Loss of oil by treatment (20 per cent of weight of fuller's earth) do 
Cost of fuller's earth (2\ cents a pound) 
Cost of oil lost (10.5 cents a pound) b 
Total. 
Cost of above items per pound of crude oil 
Cost of above items per pound of bleached oil . 
.cent, 
.do... 
Method 1 
23, 487 
1, 174. 3 
234.8 
$26. 42 
24.65 
51.07 
0.204 
.22 
Method 2. 
23, 640 
1,182 
236.4 
$26. 59 
24.82 
51.41 
0.206 
.22 
« This is a greater percentage of fuller's earth than is used for most vegetable oils, but commercial practice 
andlaboratory tests appear to agree that such a quantity is necessary in the case of corn oil. 
b This figure represents the cost of crude oil plus the approximate cost of the treatment with caustic. 
9 The refining equipment described in this bulletin-is designed to handle 50,000 pounds of oil a week. 
This quantity of oil would be produced in a hominy plant milling from 15,000 to 18,000 bushels of corn daily. 
In a starch plant, which produces at least twice as much oil from the same quantity of corn, the refinery 
would need to be proportionately larger. 
