382 THE CHEMISTEY OF ESSENTIAL OILS
OIL OF MBLALEUCA PAUCIFLORA.This oil is quite different from ordinary Melaleuca oils. It contains
no pinene, the terpenes present consisting of limonene and (probably)
dipentene, with a little eucalyptol, a sesquiterpene, terpineol, and ter-
pinyl acetate. The characters of the oil are as follows :—
Specific gravity 0-9302
Optical rotation + 3-3°
Refractive index 1-4921 at 24
Yield 0-3 per cent.OIL OF MELALEUCA—(NIAOULI).
Oil of " Niaouli " is generally stated to be obtained from Melaleuca
viridiflora, from New Caledonia. The name was given to the plant
yielding the oil by Brongniart and Gris, but as it is quite different from
the true Melaleuca viridiflora of Solander, the plant requires a new
specific name, and should not be described as viridiflora. The oil has
the following characters :-—
Specific gravity 0-908 to 0-929
Optical rotation - 1° „ + 1°
Refractive index 1-4723
It contains d-a-pinene, Himonene, terpineol, eucalyptol, valeric and
benzoic aldehydes, and terpinyl valerianate (?).OIL OF BAY.
This oil is the product of distillation of the leaves of Pimenta acris
(Myrcia acris) and probably other closely allied species, plants flourish-
ing in the -West Indies. The yield of oil obtained is from 2 to 3 per
cent., the oil coming over in two portions, firstly, alight oil which distils
over rapidly, then a heavy oil distilling over more slowly. This, of
course, means nothing more than that there are constituents of bay oil
which have widely different boiling-points. The fact that the United
States Pharmacopoeia of 1880 gave the specific gravity of bay oil as about
1040, caused the heavier fractions to appear in commerce under that
name. Pure normal distillates, however, have a specific gravity of '965
to 1010, and oils with a higher specific gravity must be regarded as
suspicious, being possibly adulterated with oil of cloves or oil of pimento.
Occasionally distillates with a specific gravity of 1020 or thereabouts are
found with phenol values of 65 to 75 per cent., but these are rare.
The erratic manner in which this oil is distilled in the West Indies
results in a large majority of the oils reaching this country being merely
fractions of Bay oil. Umney
l
quotes the following (see opposite page)
as representing commercial samples which he has observed. Those
of very low specific gravity, however, may be actually adulterated.
Eeference to the figures recorded shows that the percentage of
phenols in oils having a specific gravity between 0936 and 0*938 may
vary as much as from 32 to 48 per cent. The strong probability is
that the reason of the variation lies in the changes which the principal
terpene, myrcene, undergoes on keeping, and especially on exposure.
Efforts are being made to improve the Bay Leaf industry in the
West Indies, with a view to a more constant quality of oil being im-
ported.
(^1) P. and E.O.R. (1916), 295.