METHOD FOR DETERMINING RESPIRATORY EXCHANGE IN MAN 



559 



Respirations are commenced with the three-way valve turned so as to 

 allow the expirations to pass directly outside. After respiratory equi- 

 librium is established, the three-way valve is turned during an inspira- 

 tory period so that the succeeding expirations may pass into the bag. 

 The time required to fill the bag comfortably is determined with a stop- 

 watch. The air which has been collected in the bag during the period 

 is thoroughly mixed and passed through a meter, the temperature and 

 barometric pressure are noted, and a sample analyzed in the Haldane 



A. B. 



Fig. 181. Haldane gas apparatus {A) and Pearce sampling tube (B). 



gas-apparatus. The bag should be emptied completely by rolling it up 

 when nearly empty. 



5. The Haldane Gas-analysis Apparatus. PRINCIPLE. The Haldane 

 method of analysis of expired air is simple and easily learned. The ap- 

 paratus (Fig. 181) consists of a gas burette, a control burette of the 

 same size (both surrounded with a water jacket), and bulbs containing 

 dilute caustic potash or soda solution for the absorption of the carbon di- 

 oxide and an alkaline pyrogallate solution for the absorption of the 



