THE PREPARATION OF CORN OIL. 3 
The oil is placed in a suitable container equipped with a mechanical stirrer and 
agitated constantly while the caustic solution is slowly added. After being stirred 
for five minutes, to insure a thorough mixing, the oil is gently heated to 55° C. over a 
15-minute period . When the oil approaches this temperature it breaks. 5 The stirring 
is now stopped and the oil allowed to stand for three hours at a temperature of 50° to 
55° C. After cooling, it is separated from the deposited soapstock. In the experi- 
ments in which small quantities were used in beakers, the refining losses were deter- 
mined by pouring off the oil from the soapstock. 
In the first experiments with method 1, caustic solutions of 10°, 
12°, 14°, and 16° Be. were used, while with method 2 the solutions 
used were of 5°, 10°, 14°, and 20° Be. strength. In each case the 
test was made on 100 grams of oil. With method 2, 10 per cent of 
caustic in excess of the quantity necessary to neutralize the free fatty 
acids was used. The results are shown in Table 1. 
Table 1. — Results of treating corn oil with several concentrations of caustic in connec- 
tion with methods 1 and 2. 
Method and 
number of 
exper- 
iment. 
Strength 
of caustic 
used. 
Refining 
^loss. 
Free 
fatty 
acids in 
treated 
oils. 
Character of settling and condition of soapstock. 
Method 1: 
1 
2 
3 
4 
Method 2: 
5 
6 
7 
8 
Be. 
16 
14 
12 
10 
20 
14 
10 
5 
Per cent. 
8.47 
5.7 
5.0 
4.6 
27.5 
11.7 
11.9 
12.5 
Per cent. 
0.033 
.031 
.037 
.047 
.076 
.047 
.026 
.056 
Rapid settling; soapstock is light and flaky and occludes 
much oil. 
Soapstock very much like that in experiment 1, but appears 
to contain less oil. 
\ Soapstock forms a semiliquid layer which hardens to soft 
/ petrolatum consistency on cooling. 
Soapstock very slimy and does not settle firmly. 
[Settles more rapidly than in experiment 5; soapstock slides. 
Soapstock liquid when hot; does not harden entirely on 
cooling. 
The soapstock obtained by the two methods differs greatly. That 
obtained by method 1 is in all cases semiliquid while warm, and on 
cooling hardens to a consistency like that of soft petrolatum. Such 
soapstock occludes very little oil, with attendant low refining losses. 
It appears that the weaker concentrations of caustic, such as 10° 
and 12° Be., give better results on corn oil. 
Method 2 results in very high refining losses, because the soapstock 
in practically all cases is very slimy and occludes much oil. Ac- 
cordingly, the most suitable concentration to use is apparently a 
strength of 14° Be. It is evident that with this method it is benefi- 
cial to add some material to harden the soapstock in order to reduce 
the refining losses.- 
The next series of experiments was for the purpose of determining 
the quantity of excess caustic that should be used in method 2. In 
all cases 1.5 per cent of soda ash was added after the break, in order 
to harden the soap'stock. Caustic of a strength of 14° Be. was used 
6 The appearance given to oil when coagulations of soap occur during refining. 
