178 A RESPIRATION CALORIMETER. 



MEASUREMENT OP INTAKE AND OUTPUT OF ENERGY. 



The intake is derived from the potential energy, i. e., heats of com- 

 bustion of the food. The output consists of sensible heat given off 

 from the body, the latent heat of the water vaporized, and the potential 

 energy, i. e., heat of combustion of the unoxidized portions of the dry 

 matter of urine and feces. In certain cases, e. g. , work experiments, a 

 not inconsiderable portion of the output is in the heat equivalent of 

 external muscular work. 



As has been stated elsewhere, the heats of oxidation are determined 

 by burning the substances in the bomb calorimeter ; the heat given off 

 from the body is measured by the respiration calorimeter ; the external 

 work is measured by a specially devised ergometer. Allowance is made 

 for heat introduced and removed by the ventilating air current, food, 

 feces, and urine, and for that involved in changes of body temperature, 

 which is also measured. 



ANALYTICAL, METHODS. 



The nitrogen is determined by the Kjeldahl method, the carbon and 

 the hydrogen by the modified L,iebig method, 1 and the heats of com- 

 bustion by the bomb calorimeter. 2 



The observers work in relays and all the work is systematized. An 

 elaborate system of checking weights and observations serves to mini- 

 mize errors or faulty manipulation. 



METABOLISM EXPERIMENT NO. 70. 



The particular experiment here used as an illustration was not pre- 

 ceded by the customary preliminary period, as it was designed to study 

 metabolism after a period of fasting. The experiment shows the met- 

 abolism on the first day after a 5-day fast. 



Since it is not the purpose of this report to discuss metabolism in 

 general, but rather to describe the apparatus and methods of calcula- 

 tion, the results for the experimental day are here given mainly in the 

 form of tables. 



SUBJECT. 



The subject was a young medical student, B. A. S., who had accus- 

 tomed himself to periods of fasting varying from 3 to 10 days. He 

 was in excellent health, and previous to beginning his fast had lived his 

 usual routine of life. 



1 Benedict : Elementary Organic Analysis. 



2 Jour. Am. Chem. Soc. (1903), 25, p. 659. 



