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HXPERIMENTS ON METABOLISM OF ENERGY. - 99 
outgo of energy, the potential energy of the food eaten and of 
the solid and liquid excretory products was determined by 
means of the bomb calorimeter,* and the kinetic energy given 
off by the subject was measured by the respiration calorimeter 
and accessory apparatus. 
THST EXPERIMENTS. 
Numerous.test experiments were made in order to prove 
whether or not the apparatus and methods gave ‘accurate 
results. According to one method a known amount of heat 
was generated electrically within the apparatus and this amount 
compared with that actually measured. It was found that the 
differences between the amounts introduced and measured were 
very small, the average being less than o.1 per cent. of the 
quantity of heat generated. 
This method gave no indication as to the accuracy of the 
determinations of carbon dioxid and water. Accordingly, 
ordinary commercial ethyl alcohol of known strength was 
burned in the apparatus and the carbon dioxid, water and 
heat produced were measured in the same way as in the 
experiments with a man. 
A considerable number of these alcohol test experiments were 
made before the apparatus was used for experiments with a man, 
and served to show that the determinations of carbon dioxid, 
_ water and heat could be made with a high degree of accuracy. 
Test experiments were also made at frequent intervals dur- 
ing the progress of the experimental investigations with men 
and served to show whether the apparatus remained in proper 
condition. In a few instances slight differences between the 
theoretical amounts of carbon dioxid, water or heat, and those 
actually found, indicated some slight trouble in the apparatus, 
which was then remedied. 
The details of the various test experiments are published in 
bulletins of the Office of Experiment Stations of the _U. S. 
Department of Agriculture.f In all, 17 test experiments have 
been made, in which over 5 liters of ordinary commercial ethyl 
alcohol have been burned. ‘The total amount of carbon dioxid 
produced was 19,240 grams, of which 19,207, or 99.8 per cent., 

* See Reports Storrs Exp. Sta. 1894, p. 135 and 1897, p. I99. 
+ Buls. 63, 69, and one now in press. » 
