532 THE CHEMISTEY OF ESSENTIAL OILS
THEACEjC.OIL OF TEA.The leaves of the tea plant, Thea chinensis, yields a minute quantity
of essential oil. Van Eomburgh
l
obtained 0'006 per cent. 6f oil which
had a specific gravity 0*866, and optical rotation - 0° 11'. The principal
constituent was found to be methyl alcohol, with possibly a little acetone
(which were recovered from the watery liquid, not forming a portion of
the oil proper). In the oil, methyl salicylate and a body of the formula
C 6 H 12 O, which appeared to be of an alcoholic nature, were detected.
The latter body yielded compounds with acetic and benzoic acids.MALVACEAE,
OIL OF MUSK SEBD.The seeds of Hibiscus abelmoschus yield from Ol to 0-6 per cent, of
essential oil of very aromatic odour. It is known as musk seed or am-
brette seed oil, and has the following characters:—
Specific gravity 0-900 to 0-905 at 15°
„ „ 0-880 „ 0-885 „ 45°
Acid value 75 to 140
Ester „ 70 „ 130
It is semi-solid at ordinary temperature, the melting-point varying
according to the amount of free fatty acids present.
The oil contains the alcohol farnesol, together with free palmitic acid
and constituents not yet identified. A sample of Java distilled oil, how-
ever, was liquid at ordinary temperatures, and a French oil of specific
gravity -908 did not solidify at - 10°.RANUNCULACE^E.OLL OF P^ONIA MOUTAN.The root bark of this plant, which is found in Japan and China,
yields a small amount of essential oil, which at ordinary temperatures is
of a solid consistency. It has the following characters :—
Specific gravity (superfused) at 15° 1*500
Optical activity 0°
Refractive index (superfused) at 20° 1-5646
Acid value 12-6
Ester „ 24-5
„ „ (after acetylation) 220'7
The oil consists chiefly of paeonol, which, according to Nagai,
2
forms
colourless glancing prisms, melting at 50°. It has the formula C 9 H 10 Oa
and the constitution C 6 H 3 (OH)(OCH 3 )(COCH 3 ). It forms a phenyl-
hydrazone melting at 170°, and is^-methoxy-o-oxyphenyl-methyl-ketone.
OIL OF NIGELLA.
The seeds of Nigella damascena yield from 0*4 to 0'5 per cent, of a
fluorescent essential oil having the following characters :—
Specific gravity 0*895 to 0'915
Optical rotation + 1°4' „ - 7-8°
Refractive index ........ 1
*
5582
1
Schimmel's Bericht, April, 1897, 42.
2
Berichte, 24 (1891), 2847.