RESPIRATION 153 



buret. Turn the stop-cocks upon its two ends, and connect its lower 

 end with the rubber tube of the pressure bottle B, containing the potas- 

 sium pyrogallate. Expel the air from the connecting tube and turn 

 the three-way stop-cock so that the pyrogallate may flow into the buret. 

 Raise the pressure tube and finally clamp the connecting tube close to 

 the buret. Turn the buret repeatedly (ten minutes) and open the 

 clamp, allowing the potassium pyrogallate to take the place of the 

 absorbed oxygen. Then remove the clamp, but allow the tubes to 

 remain in connection for another ten minutes. At the end of this period 

 adjust the level of the solution in the buret to the level of the solution 

 in the pressure tube. Take the reading. Analyze the oxygen content 

 of the normal air. Subtract the amount of oxygen of the respired 

 air from that found in the normal air. The result corresponds to the 

 amount of oxygen consumed by the animal. 



