620 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
than would be occasioned by churning milk with a mixture of ‘‘oleo’ 
and ‘‘neutral” lard. I have examined many samples of oleomar- 
garine, received directly through agents from several of the largest 
factories in the United States, the object of the purchase being un- 
known tothe proprietors, receiving a guaranty that the samples were 
of their best make, and have found that in each case they contained, as 
before stated, but a trace of butter. On crystallizing these samples 
by boiling and cooling them, the small crystals peculiar to “‘oleo” 
and lard, ‘‘ neutral” lard, were found. 
I have examined ten samples of butter-like substances, forwarded 
to the Microscopical Division by Hon. J. K. Brown, dairy commis- 
sioner for the State of New York. All of them proved to be fictitious 
butter. Several of the samples consisted of stearin, cotton-seed oil, 
and lard, colored to imitate butter. 
Many samples bought for butter and afterwards suspected as oleo- 
margarine proved on examination to be rancid butter, having a 
strong order of butyric acid. 
USE OF TERMS. 
Some scientific men, even chemists, frequently use the terms beef 
fat, ‘‘oleo,” and stearin indiscriminately in discussions relating to 
the crystallography of fats. 
Pure beef fat consists chiefly of the glycerides of stearic, palmitic, 
and oleic acids. Variations in the proportions of these fatty acids 
constitute the only essential difference between beef fat, ‘‘ oleo,” and 
lard. It is evident, therefore, that when changes are made in the 
proportions of these proximate principles of the fats, either by ab- 
straction or addition, as in ‘‘oleo,” it leads to confusion to apply the 
term beef fat to the new artificial compound. 
OLEO. 
‘‘Oleo,” a term applied by manufacturers of butter substitutes to 
a product expressed from beef fat, consists of olein and palmitin, 
with a very little stearin, the latter being a residue left in the press 
after the oil has been extracted by hydraulic pressure. The object 
of the manufacturer is to separate the stearin from the olein and 
palmitin, and thus obtain a product, ‘‘oleo,” which approaches the 
composition of milk, butter. ‘‘Oleo,” therefore, it will be under 
stood, does not represent beef fat, much less does the separated 
stearin. 
STEARIN. 
Stearin is a glyceride of stearic acid. It does not crystallize as 
quickly as stearic acid, although much more rapidly than butter or 
lard.e Were an ounce each of butter, lard, stearin, and stearic acid 
heated simultaneously in porcelain capsules and allowed to cool in 
a still atmosphere at a temperature of about 70° F., the stearic acid 
would chill and erystallize first, then the stearin, then the butter, 
and lastly the lard. Were an ounce of stearin and an ounce of 
butter melted together and cooled at the same temperature as above 
the compound would harden in thirty minutes to the consistency 
of tallow. An ounce of lard and an ounce of butter thus treated 
would not harden in less than from eight to ten hours. 
