100 THE CHEMISTKY OF ESSENTIAL OILS
Fromm and Fluck.
1
These chemists isolated a small fraction of from
1 to 2 per cent, boiling at 208° to 210
°
, which consisted mainly of an
oxygenated compound of the formula C 10 H 16 O, the exact nature of which
is undetermined. Two sesquiterpenes were separated, one boiling at
138° to 140° at 12 to 15 mm., and the other yielding a dihydrochloride
identical in melting-point with that of cadinene. But when mixed with
pure cadinene dihydrochloride, a depression of 10° in the melting-point
results, so that the sesquiterpene is not cadinene. From the highest
boiling residues, a sesquiterpene hydrate C 15 H 26 O melting at 167° was
separated. Eugenol, which has been stated to be present by Horst,
could not be found.
According to Dragendorff, the oil should not be quite soluble in an
equal volume of 85 to 90 per cent, alcohol. He states that the chief
adulterants are oils of pimento and cloves, which are much more soluble
in alcohol. The ready solubility of samples of oil in all proportions of
80 per cent, alcohol is, therefore, probably indicative of adulteration.
Oil of lemon and turpentine have also been used to sophisticate the pure
oil. These will be indicated by the lowering of the specific gravity and
the alteration in the optical rotation.
A galangal oil has also been distilled from Alpinia Galanga and has
been examined by Ult6e.^2 The oil has the following characters:—
Specific gravity....0-974 to 0-985
Optical rotation
Refractive index
Acid value
Ester „+ 4° „ + 6°
1-5164
1 to 2
145
It contains about 50 per cent, of methyl cinnamate and 20 to 30 per
cent, of cineol. Pinene is also present.OIL OF ALPINIA ALBA.Pickles and Earl^3 have made an examination of the essential oil
distilled from the fruit of this plant which is also known as Amomum
medium. They find that the oil resides almost entirely in the seeds.
By distilling the fruits with steam, about 1 per cent, of a pale yellow
oil, having an odour recalling those of lemon and eucalyptus, was ob-
tained. The oil has the following characters :—
Specific gravity 0-9366
Optical rotation - 2° 15'
The oil was shaken, first with dilute sodium carbonate, next with
sodium hydrogen sulphite solution, then with dilute sodium hydroxide,
and finally with 50 per cent, resorcinol solution to absorb cineol. From
the results of this treatment and the subsequent examination of the
various products, the composition of the oil was found to be approxi-
mately as follows: Cineol, 69 per cent., characterised by the crystal-
line additive product with iodol; aldehydes and ketones, 27*5 per cent.,
consisting mainly of citral, which was characterised by means of the
semi-carbazone and the /J-naphthacinchoninic acid ; phenols, 1'5 per
cent.; acids, 1 per cent. A small quantity of crystalline acid, melting-
point, 46° to 48° was isolated, but not in sufficient quantity for identifi-
cation. The residue, amounting to about 1 per cent., seemed, from its
odour, to consist chiefly of terpenes.
(^1) Annalen, 405 (1914), 175. (^2) Schimmel's Bericht, April, 1911, 19.
(^3) Proc. Chem. Soc. (415), 164.