TECHNIQUE FOR METABOLISM DURING WORK. 



135 



of oxygen consumed from the chamber during this prehminary period 

 would therefore be in the following ratio: 



Per cent CO2 found : per cent O2 consumed : : R. Q. : 1 

 Deducting this calculated percentage of oxygen consumed from the 

 percentage of oxygen in outdoor air would give the percentage of oxygen 

 present in the chamber at the beginning of the period, subject to a 

 correction for change in the volume of air in the chamber due to the 

 fact that more oxygen has been consumed than carbon dioxide has been 

 produced. Of the original air 100 volumes were composed as follows: 

 O2, 20.932;! CO2, 0.031; N2, 79.037; total, 100.000. The altered vol- 

 ume is composed of 79.037 parts of unchanged nitrogen plus an in- 

 creased amount of carbon dioxide, and a decreased amount of oxygen, 

 the total being less than 100. The true percentage of oxygen would 



Table 6. — Records of metabolism experiment, with subject walking in treadmill chamber. 

 Subject: Gul. Date, Feb. 3, 1918. Weight with clothes, 64 kg. Experiment began 7''18™ a. m. 



therefore be larger in the proportion as the altered volume is to 100. 

 From this corrected percentage and the volume of air in the chamber, 

 the amount of oxygen present at the start is computed. The analysis of 

 the air by the Sonden gas-analysis apparatus at the end of the experi- 

 ment gave the combined percentage of oxygen and carbon dioxide, from 

 which the percentage of oxygen was found by deducting the percentage 

 of carbon dioxide as determined simultaneously on the two Haldane gas- 

 analysis apparatus. The difference between the volume of oxygen 

 present at the start and at the end, divided by the time, gave the 

 oxygen consumed per minute. The data and calculations of a typical 

 experiment are shown in tables 6 and 7. 



1 Benedict, Carnegie Inst. Wash. Pub. No. 166, 1912, p. 114. 



