BY ETHEL C. PINKERTON. 



155 



The figures show that the percentage of carbon dioxide, in the 

 GUO c.c. passed last into the tube, remained constant within the 

 analytical error of the experiment, even when such small quan- 

 tities as 700 or 800 c.c. were released into the tube. The per- 

 centage of carbon dioxide was varied from 6 to 34*6. These 

 results show that quantities of gas, of similar volume to that ex- 

 pelled from the lungs by a forcible expiration, wash out the air 

 from the last 200 cm. of the brass tube. 



Besultti. — Numerous experiments were carried out after samples 

 of expired air had been passed along the brass tube. As an 

 example, some experiments carried out, with the author as 

 subject, may be described in some detail. The brass tube used 

 w as that employed in the control-experiments with the gaseous 

 mixture. The samples withdrawn in the first series were taken at 

 25cm. and 200cm. from the mouthpiece. Each sample measui-ed 

 about 80 c.c, and was analysed in two portions. The samples 

 distant from the mouthpiece were collected before those nearer 

 to it. The volume of the air driven from the tube was measured 

 in a spirometer, A number of breaths were discharged into the 

 brass tube before the particular breath from which the sample 

 was taken. The results are recorded in Table x. 



Table 



The two metres of the brass tube in connection with the 

 mouthpiece contained the last 625 c.c. expelled from the air 



