90 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



trol within one 12 to 13 minute period, and in one 15-minute period it is 

 possible to secure readings for three determinations of the oxygen con- 

 sumption. 



At the conclusion of a period, oxygen is again admitted, the initial 

 position of the spirometer read, connections made with the subject as 

 before, and a new period begun. All of this can be carried out without 

 stopping the motor. If, during the first period, a larger amount of 

 oxygen has been introduced than is actually consumed, a little more air 

 can be rejected by turning the 3-way valve and lifting slightly the 

 counterpoise. It is thus seen that the oxygen consumption may be 

 approximately measured by the fall of the spirometer and the actual 

 computation of this contraction in volume be completed by using the 

 data obtained regarding the temperature and barometric pressure. 



METHOD OF CALCULATING OXYGEN CONSUMPTION. 



The method of calculating the amount of oxygen consumed in one 

 period of an actual experiment may be illustrated by period 1 of the 

 experiment with Bro on January 8, 1918. (See table 3.) In the two 

 earher periods of this experiment, the mask was employed; in this 

 period the mouthpiece was used, and two sets of records were made, 

 one being included in the other. The intermediate measurement^ 

 is designated for convenience "period ia." 



Table 3. — Calculation of oxygen consumption in experiment with the portable respiration 



apparatus. 



Subject: Bro. Date of experiment, Jan. 8, 1918. 



Apparatus used: Portable respiration apparatus No. 1. Breathing appliance: Mouthpiece. 



No. of period: 1, la. Duration period 1 15'16" (15.27') 



Period 1 began 6 a. m. Duration period la 8' 8" ( 8.13') 



Height of spirometer bell. Temperature of spirometer. 



Period 1. Period la. Period 1. Period lo. 



Beginning 984 mm. 942 mm. Beginning 75 78 



End 820 mm. 853 mm. End 82 80 . 



Difference 164 mm. 89 mm. Av. (°F.) 78.5 79 



Av. (°C.) 25.8 26.1 



Barometer 740.6 mm. 



Logarithms. 



Period 1. Period la. 



Difference in height of spirometer bell 2 . 21484 1 . 94939 



Volume per mm. height of spirometer bell 1 . 32056 1 . 32056 



To reduce to 0° C 9.96071-10 9.96027-10 



To convert to 760 mm. pressure 9.98877-10 9.98877-10 



Decrease in volume at 0° C. and 760 mm. (oxygen consumed) 3 .48488 3 .21899 



Duration of period 1 .18384 0.91009 



. , /2. 30104 2.30890 



Oxygen consumed per mmute ■! _ 200c.c. = 204c. c. 



Correction for reduction of total vol. of air to 0° C. and 760 mm. 



( +1 c.c. for each rise of 1° F.) +7 +2 



207c.c. 206C.C 



Average of two measurements of oxygen consumed per minute . . . 207 c.c. 



^ In this case but one intermediate period instead of two was recorded. 



