118 



METHODS FOR THE ANALYSIS OF BLOOD 



The oxygen is removed by a similar procedure, the gas being 

 passed into the alkaline pyrogallate solution by turning cock 8 

 to communicate with bulb 12. The absorption of oxygen is slower 

 than for CCb, and more care must be taken to get complete absorp- 

 tion. The air in the tubing between the fluid in 9 and stopcock 8 

 must be washed out several times in order to get the oxygen which 

 is left in it after the absorption of the CO2. When this is complete, 

 the final reading on the burette is made and the loss in volume 

 from the second reading represents the oxygen. 



The Calculations. The calculation of the percentile compo- 

 sition of the air is represented in the following example of an 

 actual analysis: 



(The temperature and barometric pressure as taken at the 

 time of the experiment were 20 C. and 747 mm. Hg.) 



CO2 Analysis 



1st reading of burette 20.00 



2d reading of burette after absorption of CO2 .... 19.20 



CO 2 absorbed 0.80 



0.80-7-20 = 4.0 per cent CO2 in expired air. 



02 Analysis 



2d reading of burette 19.20 



3d reading of burette after absorption of COo 15.90 



O 2 absorbed. . . . 3.30 



3.30-7-20= 16.50 per cent of 02 in expired air. 



TABLE FOR REDUCING GASEOUS VOLUMES TO NORMAL 



TEMPERATURE AND PRESSURE 



The observed volume, when multiplied by the factor corresponding to 

 the temperature and pressure, will give the volume of the expired air reduced 

 toO C. and 760 mm. 



