120 



SPEC I A L PH YSIOL OGY 



The solution of potassium pyrogallate is prepared by mixing twc 

 parts of 25 per cent, aqueous solution of KOH and one part of 5 pei 

 cent, aqueous solution of pyrogallic acid. 



Comparison must be made between the oxygen content of th( 

 expired air and that of the atmosphere at the time of the experiment 

 If it is desired to calculate the respiratory quotient it will be necessary 

 to make the oxygen analysis from the air that traversed the anima 

 cage in the previous experiment when the CO 2 was being determined 



If it is not desired to compute the respiratory quotient it will b< 

 necessary only to have it traverse the animal cage, drawn througl 

 by the ventilating apparatus. 



The air should come into the cage from out of doors (brought ir 

 through glass or rubber tubes from the window). 



FIG. 63 



Position 1. 



Position 2. 

 Gas burettes to determine oxygen. 



Position 3 



2. Operation. These two constituents of the pyrogallate shoulc 

 be mixed in the pressure tube of the gas apparatus just before th( 

 analysis is made. To collect samples of air for analysis, one fills 

 the gas burette (Fig. 63, A) with water by suction. Connection is 

 then made between the exit tube at k, of the respiration apparatus 

 used in the previous experiment (see Fig. 62), and the upper end oj 

 the gas burette as shown in Fig. 63, position 1 ; the respired air flows 

 in, displacing the water. The stopcocks are now turned so that nc 

 air can escape from the burette. The rubber tube of the pressure 

 tube B, which has been filled with the potassium pyrogallate, is no\\ 



