470 THE CHEMISTEY OF ESSENTIAL OILS
extent from the fruit. The principal species used for distillation are
Bur sera Delpechiana and Bur sera aloexylon. Possibly Bur sera glabri-
folia and Bursera fagaroides are used to a small extent. The wood is
known locally as " Bois de citron du Mexique ". The oil is not to be
confused with the so-called Cayenne linaloe oil, which is derived from an
entirely different species.
According to Dr. Altamirano,^1 Mexican linaloe oil is obtained from the
districts Oaxaca, Puebla, Guerrero, Morelos, and Michoacan down to
Colima. The two trees which are or have been the principal source of
the oil are known as "Spanish linaloe" and "copal limon". The
former is now nearly eradicated, but the latter still flourishes abundantly..
The natives distinguish three kinds according to the external appear-
ance and odour: fine, common, and caraway linaloe. Fine linaloe has a
very delicate and pleasant odour, the common kind less so, and the third
resembles caraway. The wood of the linaloe tree is said to be more com-
pact than that of the copal limon, which is more spongy. The oil which
is met with in commerce is chiefly obtained from the wood of copal
limon. This tree is very hardy and grows even in very stony soil;
although it can most easily be propagated from cuttings, nobody thinks
of planting it. The young trees, however, can only be made use of for
oil production after about twenty years. It is said that during the last
few years oil has frequently been placed on the market which consisted
of a mixture of oils obtained from the wood and from the fruit. The
fruit is ripe in September, and forms fleshy, greenish to reddish berries
of the size of a Spanish pea (garbanzo}. The yield of oil from the fruit
(which is distilled from July to September) amounts to 3 per cent. The
fruit is gathered by stripping it off with a very sharp crescent-shaped
instrument, care being taken to damage the fleshy part of the berries as
little as possible ; the oil obtained in the distillation possesses a herbaceous*
odour, and resinifies very readily. For this reason it is not sold as such,
but is mixed with the oil obtained from the wood, which keeps better.
In order to increase the quantity and improve the quality of the oil, the
Indians used to submit the fruit before the distillation to a kind of fer-
mentation during which the herbaceous odour disappears, by placing the
undamaged fruit in cases well covered with sacks, and keeping it thus for
three to four days at a constant temperature so as to let the fruit mature..
The oil from the wood is best obtained from trees which are quite
old—forty to sixty years; in the case of young trees it is endeavoured to
increase the oil-content by cutting notches in the tree, upon which an
increased formation of oil takes place, which may be regarded as a patho-
logical product. The tree is treated so that strips 16 ins. long and 8 ins,
wide are cut out of the bark and the wood, down to a depth of 2 ins., and
running parallel, or preferably slanting, to the direction of the trunk. If
it is now found that the tree has a " heart," i.e. yellowish, highly aromatic
wood, it can be used at once for distillation. If the tree has no " heart,"
it is left standing with open wounds so that it may develop "heart",
With a view to this, the upper extremity of the notch is cut to a point,
in order that the rain water may run alongside, but,the lower edge is
bevelled off in such manner that no foreign material can collect there
which would set up decay. If, in spite of this, the wood should com-
mence to rot, the part is at once planed off, so as to arrest the injury
which otherwise would cause a cessation of the oil formation. If no
(^1) Report of the Inst. Med. Nac. Mexico (1904), Jan.-Mar., and Schimmel's Report.