12 BULLETIN 469, U. S. DEPARTMENT OF AGRICULTURE. 
margaric acid, for which it was often mistaken, and so it was given 
the name " margarin." Later, when soft beef fat, or oleo oil, became 
an important component of this mixture, it was called oleomargarine 
or oleo. The name does not at present, however, indicate the compo- 
sition of the oleomargarine. The principal fats used in its manufac- 
ture in the United States are oleo oil, neutral lard (that is, a spe- 
cially rendered lard), and cottonseed and other oils. All these ingre- 
dients must be pure and prepared with care in order that none of 
them shall have any marked taste or odor. These are mixed in such 
proportions as will give the final product a melting point very near 
that of butter. After being thoroughly mixed the fats are churned 
with a small quantity of milk and sometimes cream, the proportions 
of these used depending upon the quality of the product desired. In 
the preparation of high-grade oleomargarine varying quantities of 
butter are also added. The resulting product is then washed, salted, 
and worked as in ordinary butter-making processes. Owing to the 
ease with which a highly colored oleomargarine might be sold as 
butter, it is illegal to sell oleomargarine unless it is plainly labeled 
as such, and the practice of coloring it to imitate butter is discour- 
aged by a heavy tax. Oleomargarine is not used as extensively in 
this country as in Europe, where it serves both for table and culinary 
purposes. If prepared from pure materials and under sanitary con- 
ditions, it is a wholesome fat, which, according to European investi- 
gators, is well assimilated. It has an energy value of about 3,500 
calories per pound. 
VEGETABLE FATS. 
Vegetable fats are prepared on a commercial scale from oil-bearing 
seeds and fruits and must ordinarily be freed from disagreeable 
flavors and odors as well as from dirt, by-products, and harmful con- 
stituents. In general, the process involves cleaning the seeds or 
fruits and subjecting them to hydraulic pressure. Cold-pressed oils 
usually receive no further treatment. When the seeds or oily pulp 
are hot pressed, however, the raw oil is likely to contain free fatty 
acids and other organic compounds of a disagreeable nature which 
make refining necessary. The refining process is adapted to the 
properties of the oil in question. 
OLIVE OIL. 
Olive oil is obtained by subjecting the ripe olives to pressure. 
The best grade, known as virgin oil, is obtained from perfect olives 
of the proper degree of ripeness. Lower grades may be obtained 
either by crushing and pressing an inferior quality of olives or by 
a second pressing of. the residue from the first pressing of the better 
grades of fruit. The only refining or purification of the better 
