N. O. GEAMINE^E 67
lower than the figures found for normal Ceylon oils, in order to meet the
requirements of other oils, such as those from Java or the Straits Settle-
ments, and, in general, those with low terpene-content. But any Adul-
terated oil which might show a higher refractive index than has been
indicated would fail to pass the specific gravity limit if more than traces
of the adulterant were present.
For many years it was the custom to sell citronella oil " guaranteed
to pass Schimmel's test ". This was merely a solubility test, which re-
quired that the oil should dissolve in 10 volumes of 80 per cent, alcohol
with not more than slight turbidity, without any oil globules separating.
It was soon found that the oil could be adulterated down to the limits of
this test, and a so-called "raised test" was suggested, but never applied
to contracts commercially. This consisted in adding 5 per cent, of
kerosene to the oil in question, which should in this condition pass the
ordinary " Schimmel's test ". To-day, however, the empirical character
of these tests is fully realised, and discriminating buyers insist on valuing
the oil on its acetylisable constituents calculated as geraniol. This de-
termination is carried out in the usual manner for the determination of
free alcohols, the citronellal present being, converted into isopulegol and
then into isopulegyl acetate, so that the result expresses the geraniol to-
gether with the citronellal. If it be desired to determine these two
constituents separately, the process of Dupont and Labaune l may be
employed.
This depends on the fact that citronellal-oxime, produced by shaking
the oil in the cold with a solution of hydroxylamine, is converted, on
heating with acetic anhydride, into the nitrile, which is not affected by
saponification with alcoholic potash.
The difference in the molecular weight of the nitrile formed and that
of citronellal is so small as to be negligible, and the calculation of the per-
centage of geraniol from the saponification is made by the usual formula.
- The method of procedure is as follows: 10 grms. of hydroxylamine
hydrochloride are dissolved in 25 c.c. of water; 10 grms. of carbonate
of potash separately dissolved in 25 c.c. of water are added and the
mixture filtered. With this solution 10 grms. of the oil are thoroughly
shaken for two hours at 15° to 18° C. The oil is then separated, dried
by means of anhydrous sodium sulphate, and acetylated with twrice its
volume of acetic anhydride in the usual way for 1-J hours on a sand
bath under a reflux condenser. ' The oil is washed, dried, and neutral-
ised, and a weighed quantity (about 2 grms.) saponified with alcoholic
potash.
Working on a mixture of citronellal and geraniol, the authors ob-
tained 55
- 9 per cent, geraniol as against 55 per cent, theoretically
present, and when the heating with potash was prolonged for four
hours the result was not appreciably altered, showing the stability of
the citronellic-nitrile.
A Java oil which showed 83 per cent, of total acetylisable con-
stituents gave 43 per cent, of geraniol and 40 per cent, citronellal,
whilst a Ceylon oil containing 60*2 per cent, of total geraniol and
citronellal was found to contain 43 per cent, of geraniol.
The authors are convinced, by treating considerable quantities of
citronella oil, notably the Java type, that the quantity of geraniol really
1
Roure-Bertrand's Bulletin, April, 1912, 3.
