CALCULATION OP RESULTS. 8 1 



IV. The volume of air in the remaining carbon-dioxide absorbers, 

 second water- absorber, and pipe from the absorber back to the chamber. 

 To this is also added the fluctuating volume of the air in the pans. 



Volume I is measured at T , the temperature of the chamber ; volumes 

 II, III, and IV are measured at T, the temperature registered by a 

 mercury thermometer near the pans. 



As a result of the removal of carbon dioxide and water vapor and 

 the admission of oxygen, the air in the different parts of the air-circuit 

 is of varying composition, and consequently, in any calculation in 

 which the total residual amounts of carbon dioxide, water vapor, 

 oxygen, and nitrogen are to be determined, the composition of the 

 different parts must be taken into consideration. 



It is assumed that all the water vapor in the air current is absorbed 

 by the first water-absorber during the passage of the air current through 

 the acid, so that there is no moisture in the air above the acid in the 

 water-absorber. It is further assumed that, in general, by the time 

 the air current has passed through the first carbon-dioxide absorber 

 its carbon-dioxide content has been reduced to zero. A second sub- 

 division may therefore be made of the air volumes, based solely upon 

 the variations in composition of different parts of the system. 



The first two sections of the subdivision outlined above, i. <?., I and 

 II, are alike, save as regards the temperature measurements. They 

 differ from sections III and IV in that they contain water vapor in 

 addition to the carbon dioxide, oxygen, and nitrogen. The volume of 

 air containing water vapor, therefore, is the sum of I and II, and 

 may be designated Vj. The air in the third section above, i. e., Ill, 

 though free from water, contains carbon dioxide in addition to oxygen 

 and nitrogen, and consequently the total volume of air containing 

 carbon dioxide is I-fII+III. This volume is designated as V 2 . The 

 sum of the four subdivisions obviously includes the total volume of 

 air in the system, and represents the volume of carbon dioxide, water 

 vapor, oxygen, and nitrogen. This is designated as V 3 . 



COMPOSITION GRADIENT OF AIR IN CI.OSED CIRCUIT. 



In the preceding discussion it is assumed that the air in the various 

 sections of the air-circuit has a uniform composition in each individual 

 section. 



Considering the closed volume of air absolutely independent of the 

 room air, as is the case, barring leakage, it is apparent that the air in the 

 respiration chamber proper and in the outgoing air-pipe, up to the 

 time that it first comes in contact with the acid in the first water- 

 absorber, contains nitrogen, oxygen, carbon dioxide, and water vapor. 



6B 



