ADVANCED EXPERIMENTAL PHYSIOLOGY 135 



CHAPTER XXI 

 CHEMISTRY OF RESPIRATION 



The Composition of Inspired Air, Expired Air and Alveolar Air. 

 For the analysis of these different samples of air the best apparatus 

 is that of Haldane. The gas is measured in the graduated gas- 

 burette A, provided with a 

 three-way tap. Surrounding 

 the gas -burette is a water- 

 jacket. The whole is sup- 

 ported by a clamp and retort 

 stand. The gas-burette is con- 

 nected by pressure tubing to 

 the levelling tube B, which is 

 held by a spring clamp 

 attached to the retort stand. 

 The tubes A and B contain 

 mercury, and by raising or 

 lowering B gas can be expelled 

 from or drawn into A. One of 

 the connections of the three- 

 way tap is used for taking in 

 the sample, the other connects 

 the burette with an absorption 

 apparatus arranged as in the 

 figure. 



The bulb E, filled with 20 

 per cent, caustic potash, ab- 

 sorbs carbon dioxide. The 

 bulb F, filled with alkaline 

 pyrogallic acid solution, 1 ab- 

 sorbs oxygen. The water in 

 G and H protects the pyro 

 solution from the air. F can 

 be emptied and refilled through 

 K when it is necessary. The 

 tap on the absorption pipette 

 places either E or F in connec- 

 tion with the gas -burette. 



The pressure in the burette is 

 adjusted by using the potash 

 pipette as a pressure gauge and 

 bringing the potash before 

 every reading of the burette to 

 the mark M. In order to make 



FIG. 132. Haldane's gas 

 analysis apparatus. 



1 Dissolve 100 grms. of stick caustic potash in 50 c.c. of water, 

 grms. of pyrogallic acid to this solution. 



Add 10 



