128 STORRS AGRICULTURAL EXPERIMENT STATION. 
The method of computation adopted for the total diet was 
as follows: The energy of the food eaten and of the total feces 
was found by multiplying the weights of these materials by 
their heats of combustion per gram. ‘The difference between 
the energy of food and feces represents the energy of the food 
as absorbed from the alimentary canal. The amount estimated 
to be lost to the body through the urine was found by multi- 
plying the heat of combustion of the urine for the experiment 
by its weight. This gave the amount thus lost for a single 
day, and multiplied by three, the amount so lost for the entire 
experiment, since it was assumed that the loss would be con- 
stant from day to day. ‘The amount thus lost was subtracted 
from the total amount absorbed, and the remainder, divided by 
the total energy of the food and multiplied by 100, gave the 
coefiicients of the energy actually available to the body. 
The computation of the available energy of the total diet 
in experiment No. 598 would therefore be as follows: The total 
energy of the food, 8224 calories, minus the energy of the 
feces, 303 calories, gives the energy of the food absorbed from 
the alimentary canal, 7921 calories. The weight of urine for 
the third day of the experiment was 1039.2 grams and its heat 
of combustion .153 calories per gram. The energy lost in the 
urine for the three days of the experiment was therefore 477 
calories (1039.2 X .153 X 3). This amount, subtracted from 
the total amount absorbed, 7921 calories, divided by the total | 
energy of the food, 8224 calories, and multiplied by 100, gives 
90.52 per cent., the coefficient of availability of the energy of 
the total food. | 
The energy of the poultry and fish alone were computed 
according to the method described in detail in a previous report.* 
The energy of the feces from food other than poultry or fish 
was calculated from the weights of protein, fat and carbohydrates 
contained. The factors used were those elsewhere + computed 
as the heats of combustion of the nutrients in an ordinary 
mixed diet, viz., protein 5.65 calories, fat 9.4 calories, and 
carbohydrates 4.15 calories per gram. It was then assumed 
that the ratio of the energy of the total feces as calculated by 
the use of these factors to the energy of the total feces as 
* Storrs Expt. Sta. Rpt. 1904, pp. Ig1-3. 
+ Storrs Expt. Sta. Rpt. 1899, p. 104. 

