BULLETIN 1010, IT. S. DEPARTMENT OF AGRICULTURE. 
in 10, 50, 100, and 200 per cent excess, 
these tests. 
Table 2 shows the results of 
Table 2. — Results of using 10, 50, 100, and 200 per cent excess of 14° Be. caustic with 
methods. 
Exper- 
iment. 
Excess 
caustic 
used. 
Quantity 
of soda 
ash. 
Refining 
loss. 
Free 
fatty acid 
after 
treat- 
ment. 
Character of settling and condition of soapstock. 
No. 15..'.. 
No. 16.... 
No. 17.... 
No. IS.... 
Per cent. 
10 
50 
100 
200 
Per cent. 
1.5 
1.5 
1.5 
1.5 
Per cent. 
9.0 
S.2 
8.0 
7.2 
Per cent. 
0.051 
.041 
.033 
.070 
Soapstock very soft and slimy. 
Soapstock slightly .more compact than that in ex- 
periment 15, but slides in mass. 
Soapstock very much like that in experiment 16. 
Soapstock very much like that in experiments 15 
and 16. 
The foregoing tests show that although not enough soda ash was 
used to make the soapstock firm it resulted in the soapstock settling 
to a much thinner layer, so that much less oil was occluded. A num- 
ber of experiments were performed in which other dehydrating sub- 
stances were used; namely, anhydrous sodium sulphate, calcium 
sulphate (plaster of Paris), and common salt. Of these substances 
only the dry sodium sulphate compared favorably with the commer- 
cial soda ash in the hardening effect upon the soapstock. Table 3 
shows the effect of using larger quantities of soda ash in connection 
with method 2. 
Table 3. — Effect of the use of 2 and 3 per cent of soda ash on the soapstock in connec- 
tion with method 2 under several conditions. 
Refining loss— 
Experiment. 
Strength 
of caustic 
used. 
Excess 
caustic 
used. 
Quantity 
of soda 
ash used. 
By pour- 
ing off 
the oil. 
After 
heating 
and re- 
cooling 
soap- 
stock. 
Condition of soapstock. 
No. 19 
oBe. 
14 
14 
14 
14 
Per cent. 
.50 
50 
100 
inn 
Per cent. 
2- 
3 
7.7 
Q 4 
5.6 
5.9 
5.4 
No. 20 • 
Do. 
No. 21 
2 | . 6. 7 
3 5.5 
9 7 2 
Verv firm. 
Dr. 
No. 22 
No. 23 
14 2nn 
No. 24 
14 
200 
3 
7.3 
7.0 
'Do. 
It will be seen from Table 3 that the refining loss can be very materi- 
ally reduced by the use of 2 per cent of soda ash in connection with 
method 2, whether the excess caustic used is 50, 100, or 200 per cent. 
The use of an additional 1 per cent is of no advantage, because a 
greater bulk of soapstock results, with a consequent greater occlu- 
sion of oil. In all these tests the soapstock was firm and permitted 
the thorough draining off of the oil. It was found that when the 
