204 



PHYSIOLOGY OF NUTRITION. 



102. Methods for Determining the Quantity of Carbon Dioxide 

 Produced in Intramolecular and Normal Respiration. 



In Fig. 97 is depicted an arrangement which may conveniently 



be employed for investi- 

 gating the production of 

 Carbon dioxide in intra- 

 molecular respiration. We 

 will first familiarise our- 

 selves with this. The apparatus 

 to be adopted for experiments 

 on normal respiration is far- 

 simpler. 1 



It is required to pass over 

 .the research material a stream 

 of Hydrogen free from Carbon 

 dioxide, and to determine the 

 quantity of Carbon dioxide pro- 

 duced by the material. The 

 rapidity of the Hydrogen cur- 

 rent can readily be regulated 

 by means of the aspirator A, 

 which must have a capacity of 

 at least 15-20 litres. We can, 

 i.e., measure the quantity of 

 water flowing into the cylinder 

 Mj e.g. every ten minutes, and 

 so adjust the stop-cock H' /r 

 that, say, 3 litres of water 

 run off per hour. For the sake 

 of accurate adjustment this 

 stop-cock is provided with a 

 long pointer, which works over 

 the graduated arc Gb. When 

 the level of the water in the 

 aspirator gets low, the rate of 

 flow is reduced, and the stop- 

 cock H m lias to be frequently 

 regulated. It is hence of ad- 

 vantage to have the aspirator 

 as full of water as possible, 



