266 THE CHEMISTEY OF ESSENTIAL OILS
It has the formula C 10 H 14 O 2 , and forms a semicarbazone melting at
171° and an oxime melting at 54°.
SPANISH VERBENA OIL.The so-called Spanish Verbena oil was, until recently, believed to be
derived from a verbena species. E. M. Holmes,
1
however, has defi-
nitely identified it as a Labiate plant, Thymus hyemalis. He has shown
that the plant, although called Verbena, does not belong to the Verbena
family, but to the Labiate plants, and is nearly allied to the Lemon
Thyme cultivated in gardens in this country. In habit, however, it is
quite different to Lemon Thyme, having a stiff, rigid, erect growth with
woody stems, and small, short, linear leaves, in small axillary tufts
along the whole length of the stem, giving it quite a heath-like appear-
ance. Until quite recently much confusion has existed between the
different species of thyme found wild on the Continent, the species
either hybridising or varying according to the environment, so that
there has been considerable difficulty in discriminating between species-
and varieties. The full description of the plant is as follows}:—
Thymus hyemalis J. Lange: An undershrub, •£ to 1 ft. high, flexu-
osely branched from the base, with erect branchlets, the younger twigs
hoary with white hairs, the leaves short and linear with revolute mar-
gins, crowded into small tufts in the axils of the leaves, the flowers
forming small crowded heads at the tips of the branchlets. The calyx
is purplish and two-lipped, the upper lip consisting of two subulate
teeth, the lower with three short ovate acuminate teeth, the corolla of a
deep rose colour, and nearly twice as long as the calyx.
This species is related to Thymus hirtus W. and Thymus vulgar is
L., and has been placed by Boissier under Thymus mastichina L., and
by Pourret under Thymus sparsifolius, var. hyemalis, but by J. Lange it
is considered to be a distinct species. Its heath-like habit of growth is,
at all events, very distinctive, as well as the small heads of flowers, each
of which is nearly stalkless.
The oil is frequently known as Spanish Thyme-Lemon oil. The
author and Bennett,
2
have examined a sample, which had the following
characters :—
The oil is of a yellow colour, and has an odour recalling that of
thyme, but with a strong flavour of lemon, differing in this respect from
the oil derived from Thymus serpyllum (wild thyme). The latter oil
also differs in being laevo-rotatory. The following are the chief char-
acters of the sample examined :—Specific gravity at 15° C
Optical rotation in 100 mm. tube
Aldehydes (principally citral)
Proportion absorbed by 5 per cent, potash solut
Refractive index at 19° 0
„ „ of first 80 per cent, distilled
„ „ of 20 per cent, residueion0-901
+ 18° 30'
20 per cent.
10
1-4808
1-4779
1-4980
The portion absorbed by potash solution on separation proved to be
somewhat resinous, and gave only a feeble phenol reaction with ferria
chloride. A small portion of the oil was fractionated in order to give-
some idea of its possible constituents. The results were as follows :—
*P. and E.O
M. (1912), 212.^2 Chemist and Druggist,^69 (1906), 481.