I4 STORRS AGRICULTURAL EXPERIMENT STATION. 
products of respiration are determined. In this respect the 
apparatus is similar to those which are used in a number of 
places for experiments on the income and outgo (metabolism ) 
of matter, and to which the name respiration apparatus is com- 
monly given. Provision is also made for weighing and analyz- 
ing all the food and drink, and the solid and liquid excreta as 
well. By comparing the chemical elements and compounds 
received by the body in food, drink, and exhaled air with those 
given off in the solid and liquid forms by the intestines and 
kidneys, and in the form of carbonic acid gas, water, vapor, 
and otherwise by respiration and perspiration through the 
lungs and skin, we are enabled to strike a balance between 
the total income and outgo of matter in the man’s body. 
We thus measure, on the one hand, the total food and - drink 
consumed, their ingredients, the proportions of the several 
nutrients actually digested and taken into the blood to be 
used, and on the.other, the quantities of material given off 
from the body during the period of the experiment. These data, 
taken in connection with what is known of the physiological 
processes that go on in the body, give more accurate informa- 
tion than can otherwise be obtained regarding the ways in 
which the food is used, and the quantities of different food 
ingredients that are needed to supply the demands of the body 
for various purposes of work and rest. Experiments of this 
kind are commonly known as respiration experiments. 
The experiments, as above described, show the balance of 
income and outgo of chemical elements and compounds, and 
serve for the study of the metabolism of material in the body. 
It is desirable, however, to study the metabolism of energy. 
To this end it is necessary to know the potential energy of the 
food and drink, on the one hand, and, on the other, the poten- 
tial energy of the excreta and the amounts of energy given off 
in the form of heat, external muscular work, and otherwise. 
The measurements of the potential energy of the food and 
excreta are made with the bomb calorimeter. The determina- 
tion of the heat given off from the body is attempted by certain 
arrangements connected with the respiration apparatus, which 
have led to the use of the term respiration calorimeter. "The 
accurate measurement of the heat is a matter which presents 
numerous difficulties. It appears, however, that these have 
