DIGESTIBILITY OF SOME BY-PRODUCT OILS. 3 
cient quantities to obviate long hauls it apparently was necessary to 
find some use for the entire pit. 
The residue, commercially known as press cake, remaining after 
the expression of oil from peach, apricot, and cherry kernels, has 
much the same composition and nutritive value for stock feeding as 
the press cakes obtained from such oil seeds as soy bean, linseed, 
peanut, coconut, and cotton seed. Until very recently, however, the 
outer woody portion of the pits seemed to be of little value except 
for fuel purposes. Experimental tests and large-scale use of the 
carbon produced from the woody portion of fruit pits showed quite 
conclusively that this carbon is valuable, especially for the manu- 
facture of gas masks. Thus, with a possible commercial demand 
existing for all portions of the fruit pits, it seemed desirable to give 
consideration to the utilization of these by-products. 
While the oils obtainable from waste pits and seeds are satisfactory 
for a variety of technical purposes, it is of course evident that if they 
can be commercially prepared so that they are satisfactory for such 
purposes they should be available for food. Especially is this true at 
the present when a world-wide shortage of fats and oils exists. Ac- 
cordingly, laboratory studies of the expression of oils from various 
kernels were made. The results of these studies showed that if care 
was observed both in the preparation of the pits and in the expression 
of oil from them a high-grade edible oil could be obtained. 
If the peach, apricot, and cherry pits were allowed to stand for 
any length of time in the moist condition in which they were re- 
moved from the fruits, fermentation developed and the oil which 
was obtained was usually not suited for edible purposes. On the 
other hand, it was found in laboratory procedure that if the peach, 
apricot, and cherry kernels were dried, ground, and expressed by 
hydraulic pressure (i. e., "cold pressed"), the oils obtained were 
perfectly satisfactory for table purposes without any refining other 
than merely filtering. The peach, apricot, and cherry oils prepared 
in this laboratory by the above procedure were of a bland flavor, and 
when mixed with vinegar and condiments made excellent French 
dressing. In view of these findings it was decided to determine how 
well these oils are tolerated by the human body and to what extent 
they are digested. Accordingly, a supply of a number of oils which 
may be obtained from the by-products of the canning industry was 
secured, and the coefficients of digestibility were determined in the 
same manner as those of the other edible oils reported in previous 
publications. 
DIGESTION EXPERIMENTS WITH MEN. 
The subjects who assisted with this investigation were men in good 
health, whose ages ranged from 20 to 40 years. In order that the 
