Dec. 1, 1925 
Inactivation of Vitamin A by Rancid Fat 
1021 
J ieroxides in rancid fat, and of the intimate admixture of the rancid 
ard with the ration fed to rats Nos. 1 to 6, one is inclined to suspect 
that the rancid lard effected a partial destruction of the vitamin A 
that was originally added to this ration. 
EXPERIMENT 2 
In experiment 2 vitamin A was fed separately from the main 
ration containing the lard, and was thus protected from any injurious 
contact with rancid fat. The supplemental ration containing the 
vitamin A was composed of 36 per cent of dried egg yolk and 64 per 
cent of starch, and was fed to all rats equally in daily portions rang¬ 
ing from 0.3 gram at the beginning of the experiment to 0.8 gram at 
the end. In this manner sufficient vitamin A was provided to cover 
the requirements of the most thrifty of the experimental animals. 
The main portion of the ration, fed ad libitum, was made up as 
follows: 
Per cent 
Dry commercial casein_ 13. 66 
Cassava starch_ 47. 45 
Dried baker’s yeast_ r _ 9. 76 
Salt mixture 3 _ 3. 90 
Lard (sweet or rancid)_ 25. 23 
100. 00 
Naturally, each rat consumed a different amount of this ration, so 
that the quantitative composition of the total food derived from both 
rations varied from day to day and from rat to rat. The relative 
amount of the several food materials consumed by each group of 
rats as a whole, for the entire period of the experiment, however, 
was as follows: 
Per cent 
Per cent 
Sweet lard 
_22. 13 
Rancid lard 
_20. 35 
Casein 
_ 12.00 
Casein _ _ 
_11. 00 
Starch 
_49.47 
Starch. _ 
_50. 65 
Dried yeast 
_ 8. 56 
Dried veast _ 
_ 7. 87 
Salt mixture 
_ 3. 42 
Salt mixture _ 
_ 3. 15 
Dried egg yolk_ _ 
_ 4. 42 
Dried egg yolk _ _ 
_ 6. 98 
100. 00 
100. 00 
The lard used in this experiment, though from a different lot, was 
of the same type and quality and was obtained and prepared in the 
same manner as that used in experiment 1. At the beginning of the 
experiment the sweet lard contained 0.32 per cent of free fatty acids 
calculated as oleic acid, and gave a negative Kreis test and a negative 
test for peroxides. The rancid lard, on the other hand, contained 
0.48 per cent of free fatty acids calculated as oleic acid, and gave a 
positive Kreis test when diluted with 17 parts of pure mineral oil, 
and an intense test for peroxide. 
Eight rats were used in this experiment, the pertinent data con¬ 
cerning which are recorded in Table III. 
* Drummond, J. C., and Watson, A. F. Op. cit. 
