156 



CARBOX DIOXIDE IN EXPIRED ALVEOLAR AIR, 



passages. One sample represented the last 150 c.c. of expired 

 ail- to leave the mouth, while the either represented the composi- 

 tion when half a litre less was expelled. The figures show 

 that the composition had not changed on four occasions when an 

 extra half litre had passed along the tube; while, on three occa- 

 sions, the last part of the expired air contained a greater amount 

 of carbon dioxide. The mode of sam )ling was then varied 

 slightly, two samples being taken at 25c;n. and 50cm. from the 

 mouthpiece, and two at 175 cm. and 200 cm. The volume of air 

 expelled was also diminished. The results are recorded in 

 Table vi. 



Table vi. 



t After a deep inspiration. 



These results show that the gas along the tube did not vary in 

 thirteen out of the seventeen experiments; while, in experiment 

 No. 4, there was distinctly more carbon dioxide in the air near 

 the mouthpiece; and, in experiments Nos. 7, 9, and 14, there 

 seemed to be sliiihtlv more carbon dioxide in the air breathed 



