CARBONIC ACID AND VENTILATION. 103 



pulse ; and I may say that the experiment is scarcely fair 

 after 25 minutes. The disturbance on the inspirations is 

 more uniform. It is, for example, more perceptible than 

 in the next case. 



Pure air was breathed in the same position as in the 

 previous cases, D. sitting outside the lead chamber, which 

 had been well ventilated. This experiment was made in 

 order to ascertain the influence of breathing through a 

 tube, as it was feared lest some mechanical difficulties 

 might have interfered with the value of the operations. 

 The result shows that no such difficulties occurred. There 

 is a little diversity of one above and one below the average 

 of the pulse, and the breathing is a little lower in one 

 case, instead of being resolutely higher as in every other 

 case given, even when so little as one-tenth of a per cent, 

 of carbonic acid was used. 



Ordinary Atmosphere in the Lead Chamber; breathing 

 through the tubes as before. 



Pulse. Inspirations. 

 18 







74 



After 5 



minutes 74 



„ 10 



„ 



75 



» 15 



II 



74 



„ 20 



1) 



74 



. » 25 



» 



75 



" 30 



'» 



74 



,, 35 



J) 



74 



» 40 



>j 



74 



» +5 



» 



73 



., 5° 



„ 



74 



» 55 



i> 



74 



„ 60 

 Averaee 



i» 



75 



74." 



17 

 18 



17-8 



In a report on the air of mines I discussed questions relat- 

 ing to the absorption of oxygen and poisoning by carbonic 

 acid, quoting several opinions of eminent chemists. The im- 

 portant point is this : How can the blood be influenced by 



