40 BULLETIN 769, U. S. DEPARTMENT OF AGRICULTURE. 
specific demand. For instance, the best oil known for lubricating 
clocks, skips' chronometers, and other delicate instruments is obtained 
from the fat glands in the jaws or head of the porpoise. Very little 
of this oil is made, one firm producing practically the entire amount, 
but it is very valuable, bringing from S25 to S50 a gallon. 
Seal oil is also considered superior as a lubricant for fine machinery, 
and it, too, is made in comparatively small quantities. Whale oil is 
of great importance in Norway, where there are no native vegetable 
oils. After hydrogenation this oil can be used in the manufacture of 
oleomargarine. The American catch is not large enough, however, 
nor do we import a sufficient amount to warrant any such use of 
whale oil in this country. A few experimental shipments of the 
hydrogenated oil were brought in before the Great War, and it is 
possible that at some future time this oil may enter into competition 
with our hydrogenated vegetable oils for making the various com- 
pounds and margarines. 
MISCELLANEOUS ANIMAL FATS AND OILS. 
Chicken fat is rendered and packed by a number of firms for sale 
to Hebrew trade for use instead of butter during certain seasons of 
the sacramental year. It has a sweet taste, a light color, and pos- 
sesses some very desirable physical properties, This fat is also 
highly prized by some of our finest cooks in making certain kinds of 
hot breads and cakes. Since the necessity for economy in the beef, 
pork, and mutton consumption has become of such importance, it 
would seem inevitable that our supply of poultry should increase 
appreciably. The wise housewife will save all chicken fat for use 
as a substitute for butter or lard in cooking. 
One of the most important of the less common animal oils is 
horse ail, which is produced from the carcasses of horses either killed 
for meat or ordered destroyed by public health officials. This oil is 
the basis of a large proportion of the com m ercial neat's foot oil, 
which is merely a wintered horse oil. In the manufacture of many 
lubricating greases, horse oil is considered an essential constituent, as 
it is claimed to be superior to any other fat for mixing with petroleum 
greases. 
The various greases which are grouped together in Table 2 under 
the heading "Packers' and Renderers' Greases" comprise about 10 
per cent of the entire animal and fish oil production, and are handled 
under numerous more or less loosely defined trade names. Much 
of the inedible fat of the packing houses goes on the market as white, 
yellow, or brown grease, being graded according to color and per- 
centage of free fatty acid. These are largely hog fats, but may con- 
tain catch-basin skimming, some of the fat from the tankage, and the 
better grades, rancid lard and crackling greases. 
