PRODUCTION OF SWEET-ORANGE OIL. 
METHODS OF EXTRACTION. 
For use in these experiments a new type of peeling machine * was 
devised which removes the peel and at the same time ruptures the 
oil cells. As the peel comes from the machine it is in a finely di- 
vided condition (fig. 2) and the oil cells are practically all opened. 
The oil being thus released from the cells is more or less absorbed by 
the spongy remainder of the peel. The outer portion of the peel, 
in which the oil cells are contained, is of course the first to be re- 
moved by the machine, and experiments have shown that the peel 
removed by the first third of the length of the grating drum contains 
approximately 76 per cent of the oil; that removed by the second 
third contains about 23 per cent, while that from the last third 
has less than 1 per cent of oil. For this reason it was found eco- 
nomical to discard the peel removed by the last third of the grating 
drum and to employ only that removed by the first two thirds. 
Fig. 2.— Oranges before and after peeling and the finely divided peel. 
In order to recover the oil, distillation by both steam and vacuum 
was employed. It was found, however, that the oil obtained by 
means of steam distillation was not of good quality. It was either 
water white or pale yellow in color and possessed to only a very 
slight degree the valuable odor-bearing and flavoring constituents 
desirable in orange oil. 
For distilling under vacuum a special type of apparatus is neces- 
sary (fig. 3). This apparatus consists of a copper retort connected 
with a condenser and so arranged that nearly all the air within the 
apparatus can be removed by means of a vacuum pump. Distillation 
is then accomplished either by means of heat from the steam jacket 
or by direct admission of steam into the retort. 
The peel is first mixed with water to form a fairly thin paste. 
This mixture is then placed in the retort, the cover clamped down, 
and all connections made air-tight. The vacuum pump is next 
started and the air exhausted from the apparatus. As the air 
pressure becomes less the pressure can be read by means of a gauge 
1 A detailed description of this machine, covered by United States Letters Patent No. 1186317, dedi- 
cated to the public, is given in the second part of this bulletin, pages 13 to 19. 
