NORMAL PROCESSES OF ENERGY METABOLISM 539 



flows out at J and makes room for air in the two burettes (1) which fill 

 from L at K and K. When these burettes are filled and contents measured 

 the air is driven over, into the potash bulbs I, after which it is drawn back 

 into the two burettes (2), where it is again measured. Thence it is passed 

 into the phosphorus absorbers II and is finally measured for shrinkage due 

 to loss of oxygen in the two burettes (3). The burette (4) is a "thermo- 

 barometer" for recording any change in volume of the air contained in the 



Fig. 18. Respiration apparatus of Zuntz and Geppert. The recording and sam- 

 pling apparatus is shown at the left and the air analysis apparatus at the right. 

 Air enters the apparatus from the lungs of the subject at P, a sample being drawn 

 automatically through a tube L, and being passed in duplicate successively through 

 the burettes numbered 1, 2 and 3. Burette 4 is for control. The part of the apparatus 

 labeled D, E, G is a "thermo-barometer." 



burettes due to alterations of temperature and pressure during an 

 analysis. 



The apparatus R. D. E. G. is another thermo-barometer for recording 

 similar changes in the volume of the total ventilation. 100 c.c. dry air 

 at 760 mm. pressure and have been stored in two metal boxes one of 

 which is inserted into the entrance tube of the gas meter at P, and the other 

 into the exit tube. The air in these boxes communicates with the burette 

 E. The enclosed volume of air will be affected by the temperature of the 

 air entering and leaving the meter and by the atmospheric pressure, and 

 the volume changes can be read off on the burette when the water in G and 



