Florida Agricultural Experiment Station


be perfectly possible to produce a dry powder, but on account
of the inordinately long time required, as well as certain dis-
advantages inherent in the powder itself, it did not seem to
be commercially promising.
 II. THE EXTRACTION OF OIL FROM THE PEEL
 Next to the utilization of the juice of citrus fruit the ex-
traction of the oil from the peel is the most important phase
of the cull problem. On account of Italian competition, the
problem of manufacturing citrus oils in the United States is
limited to mechanical processes handling large amounts of peel
at low cost. Three fields are open; solvent extraction, pressure,
and distillation.
 It would appear at first that some process of solvent extrac-
tion would offer the best chance of usefulness. The objection
to any such process, however, is that the solvent is likely to
extract a number of things that are undesirable, such as resins,
bitter glucosides, excess of pigment, etc.
 Extraction experiments were tried with petroleum ether, chloroform,
carbon tetrachloride, acetaldehyde, and also with mixtures of solvents. On
the whole the best results were obtained with carefully washed petroleum
ether (washed to remove as much as possible of the strong gasoline-like odor).
The flavor of these extracts was quite good, but they had the disadvantage
of being strongly colored, and it was very difficult to remove the last traces
of the solvent from the extract. It was found possible to accomplish this
last result to a fairly complete extent by treating with a small amount of
alcohol and warming slightly while evacuated. While the oil thus extracted
was superior to that prepared by the use of chloroform, carbon tetrachloride,
or ether, it was not as good as the imported article. The acetaldehyde dis-
solved too much substance from the peel, and the extract presented both
aqueous and oily particles, which were very hard to separate; after separa-
tion, the oil proved to be of inferior quality.
 Accordingly, attention was next turned to methods of ex-
traction by pressure. Two forms of mechanical expression
seemed possible: (1) Between rollers held tightly together by
powerful springs; and (2) squeezing in a hydraulic or screw
press.
 The roller experiments were carried out by passing quar-
tered peels thru a heavy clothes-wringer. While this method
gave some promise of success it was discontinued in view of
more desirable developments.
 With a screw press some very good oil was obtained, but its
keeping qualities were poor and the yields were far from satis-
factory.