DIGESTIBILITY OF SOME ANIMAL FATS. 9 
It seemed of interest also to study the digestibility of the fat from 
different parts of the same animal, since these are known to vary 
materially in composition, hardness, culinary qualities, etc. In a 
series of feeding experiments to determine the best ration to use for 
producing firm rather than soft pork, Shutt 1 found that the com- 
position and physical properties of fat from animals receiving dif- 
ferent rations varied considerably. In some cases the melting 
point of soft bacon was practically 10° C. lower than that of firm 
bacon, and the fat of very young pork was almost always softer than 
that of mature animals. Henriques and Hansen 2 investigated the 
properties of the outer layer of fat in an animal as compared with 
that in the interior of the same animal body, reporting that the 
inner, and outer layers of fat are characterized by different iodin 
numbers and solidification points. In similar studies reported by 
Richardson, 3 the melting points of samples of leaf lard from oily hogs 
averaged several degrees higher than the back fat. Richardson and 
Farey 4 later found that the melting points of samples of back fat, 
leaf lard, and ham fat varied as much as 12° to 22° C. 
While the fat of beef animals may not exhibit as wide a variation 
in physical characteristics as occurs in other animals, it is well known 
that brisket fat is quite different from kidney fat. It is softer and 
has a somewhat granular appearance and has some special culinary 
uses. Inasmuch as this variation in characteristics exists, it has 
seemed desirable to test whether there may be a corresponding dif- 
ference in availability to the body. Accordingly, experiments were 
undertaken in which the digestibility of brisket fat was studied under 
conditions identical with those maintained in the study of beef 
kidney fat. 
The material used for this purpose was purchased in the open 
market, separated from the connective tissues of the brisket by the 
method of rendering previously described, and incorporated in the 
blancmange which formed a part of the simple mixed diet used in 
the digestion experiments. The results of these experiments are 
tabulated on the following page. 
1 Canada Expt. Farms Rpts. 1899, pp. 151-155; Canada Expt. Farms Bui., 38 (1901). 
2Skand. Arch. Physiol., 11 (1901), No. 3-4, pp. 151-165. 
3 Jour. Amer. Chem. Soc, 26 (1904), No. 4, pp. 372-374. 
* Idem, 30 (1908), No. 7, pp. 1191,1192. 
70239°— Bull. 507—17 2 
