The free acidity of the oil as indicated by the preliminary tests
was removed by shaking with 10 per cent aqueous sodium carbonate
solution in several portions. The aqueous alkaline extracts, after
being deprived of any adhering oil by extraction with ether, were
concentrated, acidified, and distilled with a current of steam. The
acids which were obtained separated principally as oily globules on the
aqueous distillate, which was only faintly acid.
The free insoluble acids which were separated from the aqueous
distillate by extraction with ether and evaporation of the solvent were
neutralized with a solution of potassium hydroxid and then precipitated
in fractions with a solution of silver nitrate.
Fraction 1. 0.0227 gram silver salt gave 0.0130 gram silver = 57.2
per cent silver.
Fraction 2. 0.0213 gram silver salt gave 0.0119 gram silver = 55.8
per cent silver.
It appears from the above results that the only acid existing in the
free state in the oil is butyric acid, since silver butyrate gives
theoretically 55.3 per cent of silver, fraction 1 being slightly
contaminated, due possibly to a slight excess of potassium hydrate
which was added when the acids were neutralized and which would appear
in the first precipitate.
From the remaining faintly acid distillate, after neutralization with
barium carbonate and concentrating, only a trace of precipitate,
insufficient for silver determination, resulted upon the addition
of silver nitrate solution. The butyric acid detected in the free
insoluble acids was evidently extracted by the ether, in which it is
very soluble.