oil, including menthol, menthone, menthyl acetate, cineol,
amyl alcohol, pinene, l-limonene, phellandrene, dimethyl sulphide,
menthyl isovalerianate, isovalerianic aldehyde, acetaldehyde, acetic
acid, and isovalerianic acid.

_Peru balsam oil_, the oily portion (so-called "cinnamein") obtained
from Peru balsam. Specific gravity at 15 deg. C., 1.100-1.107; optical
rotation, slightly dextro-rotatory up to +2 deg.; refractive index at 20 deg.
C., 1.569 to 1.576; ester, calculated as benzyl benzoate, 80-87 per
cent.; soluble in 1 volume of 90 per cent. alcohol.

The oil consists chiefly of benzyl benzoate and cinnamate, together with
styracin, or cinnamyl cinnamate, and a small quantity of free benzoic
and cinnamic acids.

_Petitgrain oil_, obtained by distillation of the twigs and unripe fruit
of Citrus bigaradia. There are two varieties of the oil, the French and
the South American, the former being the more valuable. Specific gravity
at 15 deg. C., 0.886-0.900; optical rotation, -3 deg. to +6 deg.; refractive index
at 20 deg. C., 1.4604-1.4650; esters, calculated as linalyl acetate, 40-55
per cent., for the best qualities usually above 50 per cent.; soluble as
a rule in 2-3 volumes of 70 per cent. alcohol, but occasionally requires
1-2 volumes of 80 per cent. alcohol.

Among its constituents are limonene, linalyl acetate, geraniol and
geranyl acetate.

_Pimento oil_ (allspice), distilled from the fruit of Pimenta
officinalis, which is found in the West Indies and Central America.
Specific gravity at 15 deg. C., 1.040-1.060; optical rotation, slightly
laevo-rotatory up to -4 deg.; refractive index at 20 deg. C., 1.529-1.536;
phenols, estimated by absorption with 5 per cent. potash solution,
68-86 per cent.; soluble in 1-2 volumes of 70 per cent. alcohol.

The oil contains eugenol, methyl eugenol, cineol, phellandrene, and
caryophyllene.

_Rose oil (otto of rose)_, distilled from the flowers of Rosa damascena,
though occasionally the white roses (Rosa alba) are employed. The
principal rose-growing district is in Bulgaria, but a small quantity of
rose oil is prepared from roses grown in Anatolia, Asia Minor. An
opinion as to the purity of otto of rose can only be arrived at after a
very full chemical analysis, supplemented by critical examination of its
odour by an expert. The following figures, however, will be found to
include most oils which can be regarded as genuine. Specific gravity at
30 deg. C., 0.850-0.858;