ANONACE^E 517
performed in dry weather. In Keunion they have succeeded in obtaining
a kilogram of essential oil per 40 kilos of flowers, and by simple but pro-
longed distillation.
This yield is too high and the oil which is obtained is then not of its
best possible value, and its value is much decreased.
In order to have a good essential oil it is necessary only to remove
from the flower 50 to 60 per cent, of its perfume, and in the island of
Eeunion a good product is obtained by only taking 1 kilo of essential
oil per 100 kilos of flowers. For this purpose, in practice, a still of one
hectolitre capacity is charged with 15 kilos of flowers which are distilled
only for nine hours, and yield 150 grams of essential oil.
The analyses which have been made show that if, with a distillation
of short duration a comparatively small yield is obtained, it is compen-
sated by the quality of the essential oil, which is the first condition neces-
sary for the commercial success of this product. It is probable that in
•order to obtain more satisfactory results, the distillation with water should
be replaced by distillation with steam, which not only gives a better pro-
duct but decreases the cost of the operation, and enables several operations
to be performed in a day with the same still.
The distillation conducted for a short time removes only the finest and
best essential oil. Some remains in the flowers, and the product which
is distilled in six or nine hours, once obtained, should be placed on one
-side. Then distillation may be continued in order to collect an inferior
or second quality essential oil, which will be worth rectifying for the pro-
duction of a medium quality which will still be commercially saleable.
The essential oil of good quality is amber-coloured. It is of lower
value if it is brown or whitish.
Immediately after distillation it should be filtered, then preserved in
•opaque vessels of glass, tin, or tinned copper. The vessels should if
possible be fitted with ground-in stoppers.
Attempts have been made to cultivate the ylang-ylang tree in Amani,
by the German colonists there, but from a commercial point of view the
experiments were unsuccessful.
Madagascar, the Seychelles, and various other places have produced
the oil, but so far not in any important quantities.
The characters of ylang-ylang and cananga oils are very variable,
not only on account of the variability in cultivation, climatic conditions,
etc., but also owing to the fact that the oil is prepared by a fractionation
process, the individual distiller stopping the distillation at such point as
he conceives to yield the best combination of quality and quantity.
The following values, which must be accepted with the above quali-
fications, cover most authentic samples of the types mentioned:—
MANILA YLANG-YLANG OIL.Specific gravity....... 0'908 to 0*967
Optical rotation - 27° „ - 87°
Refractive index 1-4800 „ 1-5082
Ester value 42 „ 155
It is soluble in 0'5 to 2 volumes of 90 per cent, alcohol.
Bacon has examined twenty-three samples of oils considered to be
of the best quality, and thirty-six samples of second grade, which he
found had the following characters:—