540 



JOHN K. MURLIN 



E has been brought to the same level by moving G. The burette is so 

 divided that, if a volume of say 107.4 is read off during an experiment, 

 the volume of air which has passed through the meter can be reduced to 



normal conditions (0 and 



is is 760 mm. dry pressure) by mul- 



tiplication with '. This 



arrangement is certainly not 

 more accurate and scarcely 

 more convenient than to re- 

 duce by means of a table after 

 reading the barometer and a 

 thermometer placed in the exit 

 tube of the gas meter. 



d. Air Analyzers, With 

 either the spirometer method 

 or the bag method of collect- 

 ing expired air or with the 

 Jaquet type Q f chamber 

 an absolutely essential 

 part of the apparatus is a re- 

 liable device for determining 

 carbon dioxid and oxygen vol- 

 iimetricially. The apparatus 

 most used to-day is the Hal- 

 dane analyzer. This appara- 

 tus is fully described by Hal- 

 dane in his book entitled 

 "Methods of Air Analysis." 

 (Haldane(c).) 



In a general way the 

 method is as follows: A 

 sample of air drawn into a 

 10 c.c. burette is accurately 

 measured under the atmos- 

 pheric pressure; the air is 

 then passed into a potash bulb 

 and back into the burette until 



a constant reading is obtained; the difference is the volume of CO 2 

 in the sample. In the same way the oxygen is absorbed in a solution of 

 pyrogallol in strong potash and the difference in volume obtained repre- 

 sents the volume of oxygen in the sample. 



As used by Boothby in the Mayo clinic the apparatus is shown in Fig. 

 19. Full details for manipulation of the apparatus and for calibration of 



Fig. 19. The Haldane air analyser as used 

 by Boothby. 1. Water-bath. 2. Burette. 3. Con- 

 trol tube. 4. Glazed glass back of water-bath. 

 5. Pressure tubing connecting burette and its 

 mercury reservoir. 6. Mercury reservoir. 7. 

 Ratchet and pinion. 8. Burette tap. 9. Sampling 

 tap. 10. Sampling connection. 14. Potash tap. 

 15. Level marking on potash pipette. 16. Potash 

 pipette. 17. Potash reservoir. 18. Control tube 

 tap. 19. Pyro tap. 20. Level marking on pyro 

 pipette. 21. Pyro pipette. 25. Level marking on 

 manometer tube. 



