6 
BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE 
From these measurements it is apparent that there is an optimum 
proportion of soap above which there is on standing a marked sepa- 
ration of the soap from the emulsion and below which there is a tend- 
ency for the glooules to increase in size to such an extent that the 
mixture either fails to emulsify or easily breaks after emulsification. 
Soaps vary greatly in emulsifying power, some brands being use- 
less and, in fact, two batches of the same brand may vary greatly in 
emulsifying power (7) . Under these circumstances the writers found 
it necessary to test each purchase of soap before emulsifying any 
quantity of wormseed oil for experimental purposes. In practice, 
in the hands of the novice, any deficiency in the soap used might 
easily result in an unstable emulsion. The writers therefore made a 
series of tests to determine the possibility of preparing wormseed-oil 
emulsion by means of such standard materials as oleic acid and 
sodium or potassium hydroxide, according to the equation — 
C 8 H 17 CH:CH(CH 2 ) 7 COOH + NaOH = H 2 0+C 8 H 17 CH:CH 
(CH 2 ) 7 COONa. 
In making these emulsions the oleic acid was added to the oil and 
shaken, then N/10 NaOH or N/10 KOH was added. The mixture 
emulsified immediately. 6 The various tests are compared in Table 3. 7 
In using these emulsions in practice it seems advisable either to 
use the oleic acid or, if a commercial brand of soap is employed, to 
be absolutely sure by test that the material will produce a stable 
emulsion. 
Table 3. — Preparation of wormseed-oil emulsions with oleic acid and an hydroxide 
Emulsion number 
Quantities of— 
N/10 
NaOH 
Remarks on emulsions formed 
Oil 
Acid 
1A 
C.c. 
20 
20 
20 
20 
20 
20 
20 
C.c. 
0.12 
0.24 
0.40 
0.80 
1.20 
1.60 
2.00 
C.c. 
3.76 
7.56 
12.60 
25.20 
37.80 
50.40 
63.00 
2 A 
Oil separated out in 1 hour. 
3 A 
4 A .. 
5A.. 
6 A... 
7 A 
Emulsion 
Quantities of— 
N/10 
KOH 
Oil 
Acid 
Remarks on emulsions formed 
8A 
20 
20 
20 
20 
20 
0.20 
0.40 
0.60 
0.80 
1.00 
6.30 
12.60 
18.90 
25.20 
31.50 
Oil separated out. 
9 A 
10 A 
11 A 
12 A.. 
• The molecular weighl of oleic acid is 2*2.37 and its specific gravity is 0.89; it follows that 317.3 cubic centi- 
meters of the icid will make a normal solution. Therefore 317.3 cubic centimeters of oleic acid is neutrali- 
zable by 1,000 cubic centimeters of normal sodium hydroxide, or 0.03173 cubic centimeter of oleic acid by 1 
cubic centimeter N F/10 sodium hydroxide. Conversely, l cubic centimeter of oleic acid is neutralizable by 
81.6 cubic centimeters of N/10 NaOH. 
7 The writers have been guided in the preparation of these emulsions by Clayton (1). 
