436 THE CHEMISTKY OF ESSENTIAL OILS
the extraction of the fresh flowers with petroleum, and extracting the
petroleum extract with alcohol, traces of phenyl aceto-nitrile and a
crystalline body melting at 158°, a ketone with a jasmine-like odour,
possibly identical with jasmone, and a high boiling sesquiterpene alcohol
(nerolidol ?), with traces of a base apparently belonging to the nicotine
series.
OIL OF PETIT-GRAIN.The original oil of petit-grain was obtained by the distillation of the
small unripe orange berry, which, according to Pereira, rapidly underwent
decomposition. The petit-grain oil of to-day, however, is distilled from
the leaves and young shoots of the bitter orange.
The best petit-grain oil is distilled in the south of France, a certain
amount also in Algeria and Spain, and a large amount of less perfume
value is distilled in Paraguay, which form the bulk of the oil of
commerce.
The distillation in Paraguay is carried on in small factories in the
immediate vicinity of orange forests, as the total absence of all means of
communication renders it impossible to centralise the production. Every
group of factories is managed and superintended by one employee. The
woods have always the character of timber forests of the most diverse
varieties, among which is found a sort of undergrowth of smaller dimen-
sions, with patches almost completely covered with orange trees, which
the inhabitants call manchones. Such manchones are scattered about the
forests at certain distances.
In specially favourable situations the bigaradier predominates, in
others the latter is found mixed with the sweet orange and with another
species called assessu, which is a variety of the two first-named. This
species is used preferably for the manufacture of petit-grain oil.
Although the orange forests are very numerous in Paraguay, they
afford but rarely the preliminary conditions necessary for normal working,
as they are mostly far removed from inhabited centres. The leaves are
gathered all the year round, but chiefly between October and April, during
which period the bulk of the oil is produced. For this purpose the trees
are cut down at a height of about 2 ins. from the ground ; the leaves and
young fruit are distilled together, and the wood of the trees is used as
fuel for the boiler.
During the past few years a number of samples of Paraguay petit-
grain oil have been found which had an optical rotation up to + 8° or
- 9°. This appears to be due to the distillation material containing
small, immature fruits, the essential oil of which contains much dextro-
limonene. Normal Paraguay petit-grain oil has the following characters:—
Specific gravity
Optical rotation
Refractive index
Acid value
Ester „0'885 to 0-900- 3° to + 11° (usually under + 5°)
1-4590 to 1-4655
1 „ 3
105 „ 166
The oil is soluble in 1 to 2 volumes of 80 per cent, alcohol, but in the
case of oils with a high dextro-rotation, the presence of limonene may
cause a slight turbidity in the solution. Subject to the same consideration,
the oil is soluble in 3 to 5 volumes of 70 per cent, alcohol.
French petit-grain oil has the following characters :—