


RESPIRATION CALORIMETER AND EXPERIMENTS. Zar 
the body—proteids, fats, and carbohydrates—are burned, ts their 
potential energy transformed into the equivalent kinetic energy 
and into forms which can be measured by the means here used ? 
Or, to state the question more broadly, does the law of the con- 
servation of energy obtain in the living organism ? 
The experiments with a man each continued during eight days, 
during the last four days and five nights of which the subject was 
mm the respiration chamber. The diet during each experiment was 
uniform through the whole eight days. The purpose of the pre- 
liminary period of four days was to bring the body into at least 
approximate nitrogen and carbon equilibrium with the food and 
to make the determination of the amounts of nutrients absorbed 
as nearly accurate as practicable. The income and outgo of nttro- 
gen were determined during this period, which thus amounted to 
a digestion and metabolism experiment. The metabolism of nttro- 
gen, carbon, hydrogen, and energy was determined during the 
final period of four days. 
Ln one of the two experiments the man had as little muscular 
exercise as he could well have with comfort. In the other he was 
engaged in quite active muscular exercise. The external muscu- 
lar work was expended in driving a dynamo which produced an 
electric current, The latter was passed through a resistance coil 
and the energy was transformed into heat which was measured 
with that given off from the body. 
The differences between the income and outgo of energy as 
measured in these two cases were 3.2 and 1.1 per cent., and aver- 
aged 2.2 per cent. The amount of energy as measured was in 
each case less than the theoretical amount of potential energy tn 
the material consumed. The larger discrepancy was in the first 
experiment, Certain sources of error tn this appear to have been 
eliminated, at least in part, in later experiments, of which the 
second was one. In these latter the agreement ts very close, the 
energy found being about ninety-nine per cent. of the theoretical, 
On the whole the agreement between theoretical amounts of energy 
transformed and those found in the experiments ts as close as 
could be expected under the circumstances. 
It would-be wrong to assume that these experiments demonstrate 
completely the conservation of energy in the animal organism. 
They do, however, approach very closely to such demonstration for 
the case of the man under experiment. — 
17 
