272 THE CHEMISTRY OF ESSENTIAL OILS
From Dried From Fresh From
Flowers. Flowers. Leaves.
Specific gravity.. 0-915 afc 26° — 0-921 at 24°
Optical rotation.. + 23-9° — + 1'96°
Refractive index.. 1-4987 at 26° 1-5031 at 26° 1-4893 at 27°
An oil distilled in the West Indies, from Lantana odorata was found
to have an odour recalling that of amber and hyssop, and had the fol-
lowing characters :—
Specific gravity.". '. 0*9149
Optical rotation
Refractive index at 20°.
Ester value
,, „ (after acetylation)- 1° 36'
1-4963
4-7
51
CONVOLVULACE/E,
OIL OF EOSEWOOD.Eosewood oil or rhodium oil as met with in commerce is almost, if
not quite, invariably an artificial mixture of several essential oils in
which true oil of roses and oil of geranium or Indian geranium are re-
sponsible for the rose or rose-geranium odour. The true oil of rhodium
is distilled from the wood, either of the stem or the root, of Convolvulus
scoparius and Convolvulus floridus, two species indigenous to the Canary
Islands. It is a thick, viscid, pale yellow oil, darkening on keeping.
It has an agreeable rose-like odour and sharp aromatic taste. An oil
examined by Gladstone, but whose authenticity is uncertain, had a
specific gravity 0*906 and an optical rotation - 16°. According to
Gladstone, it contains 80 per cent, of a terpene; but the authenticity
of the sample examined by this chemist is not guaranteed. It is more
probable that a large quantity of sesquiterpene is present. According
to Schimmel & Co. the oil solidifies at low temperatures to a mass of
acicular crystals melting at 11° to 12°. An oil, also of uncertain origin,
examined by these chemists had the following characters:—
Specific gravity 0-951
Optical rotation + 1° 30'
Acid value 0
Ester „ (after acetylation) 151-3
The oil is chiefly used in soap perfumery. The Bois de rose femelle
is the wood of the so-called Brazilian lign-aloe, and yields the corre-
sponding linaloe oil. It is one of the Burseracea, and has no connection
with the above-described rosewood.
PRIMULACE>E,
OIL OF COWSLIP.The fresh roots of Primula officinalis, when strongly bruised, develop
more or less rapidly, but always very distinctly, a marked odour. This
odour recalls at first that of anise, but that of methyl or amyl salicylate
finally predominates.
Further, if the roots thus bruised be treated with ether, a residue is
left on evaporation of the ether which, when dissolved in a little water,
gives a violet-blue coloration on the addition of dilute ferric chloride.