The determination of the free acids was accomplished by repeatedly
shaking a portion of the original oil with a 10 per cent sodium
carbonate solution. After removing the adhering oil from the alkaline
liquid by shaking with ether, the solution was acidified and distilled
with a current of steam. A few oily globules floated on the surface of
the liquid. These were extracted with ether and the ether evaporated.
A small amount of oily residue remained, which was distinctly acid.
The oily residue was exactly neutralized with sodium hydrate and
precipitated with silver nitrate solution in three fractions:
Fraction 1. 0.0377 gram silver salt gave 0.0162 gram silver = 42.9
per cent silver.
Fraction 2. 0.0206 gram silver salt gave 0.0091 gram silver = 44.1
per cent silver.
Fraction 3. 0.0663 gram silver salt gave 0.3000 gram silver = 45.2
per cent silver.
The three fractions appear to be a mixture of caprylic and œnanthylic
acids. Silver caprylate requires 42.9 per cent silver; silver
œnanthylate requires 45.5 per cent silver.
A small amount of the insoluble free acids was therefore caprylic acid
(octoic acid), the major portion being œnanthylic acid (heptoic acid).
The distillate from which the oily acids were extracted by ether
was still slightly acid and was accordingly neutralized with sodium
carbonate and precipitated with silver nitrate, two fractions being
obtained. The first corresponded to silver carbonate, due to a slight
excess of sodium carbonate; the second, only trifling in quantity,
indicated the presence of only a trace of formic acid in the free
condition.
Œnanthylic, or heptoic, acid seems to be the predominating free acid in
the oil, with slight traces of formic and caprylic, or octoic, acids.