DIGESTIBILITY OF SOME ANIMAL FATS. 3 
the temperature of boiling water, to drive off surplus water and thus 
improve its keeping qualities. Care was exercised not to heat the fat 
too high. 1 Judged by the usual household tests, the resulting product 
in all cases was most satisfactory, being of good color and flavor and 
free from sediment. 
As sufficiently large quantities of the fats to be studied could not 
be consumed in the natural state, a method of preparing them for 
eating was sought. The most satisfactory one found was to incor- 
porate the fat in a blanc mange or cornstarch pudding. This was 
best prepared by cooking skim milk, to which sugar and a consider- 
able quantity of a caramel solution had been added, in an ordinary 
double boiler, at as high a temperature as could be reached (nearly 
100° C). A mixture of commercial cornstarch and the fat under 
consideration was then slowly added with continuous stirring, and 
the heating continued until the starch was well cooked. Skim milk 
was used to avoid the presence of any considerable amount of butter 
fat, which would interfere with the study of the particular fat under 
consideration. The caramel solution was designed to mask the pres- 
ence of the large quantity of fat by supplying a characteristic and uni- 
form color and flavor to the blanc mange, for a distinctly fatty flavor is 
disagreeable to many persons and, furthermore, experience has shown 
that it is highly desirable in making experiments of this character to 
avoid as far as possible any psychic effects, which in some instances 
may play an important role in the digestion of food. It was usually 
necessary to add such a large quantity of the caramel solution that 
the blanc mange had a slightly bitter taste, but this feature was 
readily overcome by the addition after cooling of a little vanilla extract. 
The blanc mange prepared in this way resembled a common household 
dessert, except that it was not noticeably sweet. It has been used 
to a considerable extent and with good results in this laboratory as a 
medium for supplying special foodstuffs in experimental diets. The 
question of the nature of the food was not discussed with the subjects 
and the masking of the fat was so complete that none of them appeared 
at any time to notice differences in the flavor of the blanc mange ; at 
least no comments on the matter were made. 
In studying the digestibility of a single food, experience has shown 
that it is desirable to incorporate it in a very simple mixed diet, since 
the ordinary individual is so accustomed to a mixed diet, that, no 
matter how palatable a single food may be at first, it eventually 
becomes distasteful. Consequently, in these experiments it was 
decided to use, in addition to the blanc mange containing the fat under 
consideration, a very simple mixed basal diet composed of a commer- 
cial wheat biscuit, fruit, and tea or coffee, with a little sugar if the 
subject desired. 
1 It has been noted in the Biochemic Laboratory of-the Bureau of Animal Industry that the keeping 
qualities of fats which have been subjected to elevated temperatures have apparently been lessened. 
