254 



GAS METABOLISM OF BACTERIA 



Henderson-Haldane gas apparatus' is extremely accurate, and has proved very satisfactory. 

 Figure 3 shows the method of connecting the gas burette with cock 3 of the manometer for 

 the purpose of withdrawing a sample of the gas for analysis. The gas sample is then measured 



Fig. 3. — The modified Henderson-Haldane apparatus on stand with adjustable platforms to 

 hold the manometer and culture tube or Novy jar. The gas sample is drawn from cock 3 on the 

 manometer, through the capillary connector, into the burette. 



and analyzed. The CO2 is determined by absorption with KOH after which the O2 is re- 

 moved by alkaline pyrogallate. If combustible gases are present, a known amount of O2 is 

 now mixed with the sample, the gas passed into the combustion chamber, and the platinum 

 wire heated to a dull-red glow to give a temperature which is sufficient for the ignition of H,. 

 To determine hydrocarbons, such as methane, the wire must be raised to a bright red so that 



' Novy, F. G., Roehm, H. R., and Soule, M. H.: loc. cit. 



