PRODUCTION AND CONSERVATION OF FATS AND OILS. 23 
fleshy portion, and the seeds. Just as the pulp of the olive gives 
up its oil, the fleshy part of the palm fruits, the color of which is, 
when ripe, an orange or yellowish brown, yields palm oil. This por- 
tion of the fruit can not be, or at least never has been, dried and 
exported, so that the United States is entirely dependent upon foreign 
lands for its supply of palm oil. While there was a decrease in our 
imports of this oil from over 52,700,000 pounds in 1912 to less than 
30,000,000 in 1916, during the year 1917 we obtained 34,257,000 
pounds in spite of the difficulties of trans-Atlantic shipping. 
PREPARATION. 
The natives crush the soft palm oil from the fruit, often by treading 
it with their bare feet, after which the kernels are removed. The 
crushed pulp is then allowed to ferment in pits, and the oil, as it 
gradually separates and rises to the top, is scooped off into gourds 
or other crude containers, and sold to the local factories. Before being 
exported it is sometimes remelted and strained. For their own use as 
a food oil, the Africans crush and boil with a little water some of 
the best fruit to get what is called "chop" oil. This, however, is 
seldom exported. 
USES. 
In the United States the yellow unbleached palm oil is used very 
largely in the tin-plate industry. So far it is almost the only sub- 
stance which has been found satisfactory as a flux on the discharge 
side of the pots of melted tin through which the sheet-iron plates are 
passed to receive their coats of tin. Recent experiments with hydro- 
genated cottonseed oil, however, indicate that our tin-plate industry 
will be independent of this foreign controlled oil. 
Palm oil can be bleached almost white, in which state it is used in 
combination with other oil in the production of palm oil soaps. 
CORN OIL. 
INCREASING IMPORTANCE. 
Corn oil, which, so far as is known, is made only in this country 
and Canada, has within the last decade come into prominence as 
both a food and technical oil. No reliable figures are obtainable on 
the production of this oil previous to 1912, when nearly 73,000,000 
pounds were made in 16 mills. Our export of corn oil has decreased 
steadily from 1912, when we shipped nearly 23,000,000 pounds, to 
1917, when only a little over 4,700,000 pounds were exported. This 
decrease probably was due to competition with new oils in the foreign 
markets, and also, to some extent, at least, to an increased domestic 
demand for corn oil. It is only within the past few years that the 
refining processes have been so perfected that this oil could be used 
