The original oil was slightly acid, as indicated by the acid number
previously mentioned. The free acid was shaken out from a quantity of
the oil with a 10 per cent solution of sodium carbonate. The shaking
was repeated several times and the alkaline liquids united. The united
alkaline liquids were shaken out with ether in order to remove any oil
held in suspension. The sodium-carbonate solution was then evaporated
to a small bulk on a water bath, acidified with sulphuric acid, and
distilled with steam. No oily globules separated, showing absence of
higher insoluble acids. The distillate, which was decidedly acid, was
neutralized with sodium-carbonate solution and evaporated to a small
volume. The liquid which now represented the sodium salts of the free
acids present in the oil was precipitated fractionally with a dilute
silver-nitrate solution. Four fractions resulted. Each fraction was
dried to constant weight and burned.
Fraction 1. 0.1014 gram silver salt = 0.0785 gram silver = 76.3 per
cent silver.
Fraction 2. 0.1000 gram silver salt = 0.077 gram silver = 77 per cent
silver.
Fraction 3. 0.1116 gram silver salt = 0.0859 gram silver = 76.9 per
cent silver.
Fraction 4. 0.1088 gram silver salt = 0.077 gram silver = 70.8 per
cent silver.
Fraction 4 indicates the presence of formic acid, the silver salt of
which requires, theoretically, 70.5 per cent of silver. Fractions 1, 2,
and 3 indicate silver carbonate (which requires, theoretically, 78 per
cent of silver) with a slight admixture of silver formate. The presence
of silver carbonate was caused by a possible slight excess of sodium
carbonate being added when the acid distillate was neutralized.