440 THE CHEMISTRY OF ESSENTIAL OILS
harvest lasting from September to January. The oil is really a by-
product obtained by distillation during the concentration of the lime-juice,
and the peculiar odour is due to the partial decomposition of the oxy-
genated constituents. Citral decomposes into cymene when boiled with
dilute acids. It contains pinene, limonene, cymene, dipentene, bisabolene,
and Z-terpineol, melting-point 35°, and another alcohol having a strong
lime-like odour forming a urethane, melting-point 131°, but not yet
identified. Distilled lime oil has the following constants :—
Specific gravity 0'860 to 0'872
Optical rotation + 33° „ + 47°
Refractive index 1-4700 „ 1-4715
Aldehydes 1 to 2 per cent.
Hand-pressed West Indian limes oil is of considerably higher value
than the distilled oil. Its characters are as follows :—
Specific gravity 0'878 to 0*902
Optical rotation + 30° ,, + 38°
Refractive index 1*4820 „ 1*4860
Fixed residue 9 to 18 per cent.
Citral.. , 6 „ 9
The fixed residue has a saponification value of 160 to 180. This oil
contains citral, bisabolene, methyl anthranilate, and citraptene.
The leaves of the West Indian lime tree yield an oil on distillation,
which has the following characters :—
Specific gravity 0*877 to 0-878
Optical rotation + 37° „ + 38°
Acid value ......... 3 „ 5
Ester „.22 „ 25
Aldehydes 43 per cent.
The author has examined an oil distilled from the flowers of the
Italian lime tree, and found it to have the following characters :—
Specific gravity 0'870
Optical rotation + 21° 30'
It contains linalol and methyl anthranilate.OIL OF BEBGAMOT.This oil is obtained by expression from the fresh peel of the fruit of
Citrus aurantium subsp. Bergamia, the ordinary bergamot. The chief
centre of the industry is Southern Calabria, which is practically the only
province in which the tree is cultivated, extensive plantations being
situated at, and in the neighbourhoods of, Beggio, Melito, Gallico,
Arangea, Sancta Catarina, S. Lorenzo, Palizzi, Staiti, etc. Almost all
the oil is expressed by machines, but as these are usually adjusted for
globular fruits, any that have the oblong lemon shape are treated by
hand. Hand-pressed oil is, however, rarely met with in commerce. The
trees are best grown on well-irrigated, low-lying lands, and are frequently
cultivated amongst the lemon and orange trees. The fruit is gathered in
the months of November and December and the first week or two in
January, when the manufacturing season is over. The resulting oil is
of a green colour, due to the presence of chlorophyll (not to the presence
of copper, as sometimes stated).
The bergamot tree is a very delicate one, and any inclemency of the
weather will adversely affect the fruit v ry seriously. Excess of either