414 THE CHEMISTEY OF ESSENTIAL OILS
the oil is removed from the burst oil cells of the peel by a sponge. (2)
The ecuelle method, by which the lemons are rolled about in vessels
covered with spikes and the oil collected in a receptacle in the handle of
the vessel. (3) Machine processes. (4) Distillation. This method gives
a very inferior oil, and is often applied to the peels from which all the oil
obtainable by other processes has been obtained. (5) Expression in bags
in ordinary presses, now rarely, if ever employed.
The sponge method is the typical process in use in the chief lemon
oil districts—Sicily and Calabria; the ecuelle method being employed
chiefly in the South of France and North of Italy, and to a certain ex-
tent, of course, in the south.
The sponge method of obtaining lemon oil has been described by
many manufacturers. Probably the description by Mr. Arthur Barrett^1
is as accurate as any. It is as follows: "The principle on which
ihe extraction of the essence is carried out may be illustrated in this
way. If you hold a piece of lemon peel up to the light, and turn
it inside out, a fine shower of mist will be seen to be forcibly ejected.
This is not all oil, but a mixture of oil and water. Most people are
unpleasantly acquainted with this phenomenon, though many may
not have actually seen it, for in peeling a lemon or orange with the
fingers a little of the oil is often ejected into the eye, causing a con-
siderable amount of pain. By turning the lemon peel inside out
almost the whole of the essence is removed from the peel, for each
little globule of oil appears to be surrounded by water, and the liquid
which remains adherent to the peel consists principally of water. As
it is impossible to turn every piece of peel actually inside out, the
following method is adopted : One man takes a lemon in his hand, and
with three rapid strokes with a large knife cuts off nearly all the peel in
three slices. The central portion which is left consists of most of the
pulp with a little of the peel—top and bottom. This is simply, pressed
for making lemon juice. The slices pass to a second workman, who sits
on a low chair with a common quality bath sponge, worth about sixpence,
in one hand. With the other he presses the slice of peel against the
sponge, pressing the edges of the peel only with his fingers, the object
being to press the convex piece of lemon peel as nearly flat as possible.
The amount of pressure used is very slight, and at first sight it seems in-
credible that the oil globules can have been broken; but, if you try the
experiment of turning this exhausted peel inside out, nothing more can
be extracted. The sponge is periodically squeezed. One man working
in this way can extract 1£ lb. (English) essence of lemon per day. To
ensure the cells being fully charged with moisture it is usual to allow the
lemons to stand in water for a short time ; and I myself propose washing
the lemons in a stream of running water."
The Scorzetta process is a variation of the ordinary sponge method.
The fruits are cut into two halves, the pulp is removed with a kind
of spoon, and all the parts of the peel are then pressed against a sponge
by constantly turning it in the palm of the hand. This method has the
advantage that the peels remain unbroken, and retain their original
appearance. After they have been deprived of the oil, they are salted,
and then exported under the name "Salato". The pulp also remains
unimpaired, so that it yields its full supply of lemon juice. After having
passed twice through the pressers it is used for feeding cattle.
(^1) Year Book of Pharmacy (1892), 505.