OXYGEN RESPIRATION 4 1 



An analysis of a gas mixture of carbon dioxide, oxygen and 

 nitrogen has just been described. Determinations of hydrogen, 

 carbon monoxide, methane, ethylene and other gases could also 

 be carried out in the apparatus of Polowzow-Richter. The 

 analysis of a gas mixture of carbon dioxide, oxygen, hydrogen 

 and nitrogen is performed as follows. First the carbon dioxide 

 is measured, then the gas is conveyed to the explosion pipette 

 where it is exploded with the addition of illuminating gas. If a 

 decrease in total volume has taken place after the explosion, a 

 quantity of CO-i-free air, accurately measured in the measuring 

 tube, is added to the gas and again exploded with illuminating 

 gas. If the total volume remains unchanged after the second 

 explosion or if all the oxygen introduced with the air is not used 

 up by the explosion, the volume of hydrogen is computed as 

 follows: if a were the volume of the gas to be analysed, after the 

 C02-absorption, and b, after the explosion, the volume of the 

 hydrogen equals ~i(a — b), in case no change in volume 

 occurred after the second explosion.^ If the gas which was com- 

 bustible with oxygen were pure hydrogen, no trace of CO2 

 would be produced by the explosion. This is tested by treat- 

 ment of the gas mixture with caustic potash after the explosion. 

 It is best to use another sample of gas for the determination of 

 oxygen, and in the admission of hydrogen the amount of 

 hydrogen already in the gas mixture to be analysed is taken into 

 account. Consideration of the procedure of analysis of carbon 

 monoxide, methane and ethylene must be referred to the man- 

 uals of gas analysis, particularly to Bunsen's " Gasometrische 

 Methoden. '2 



It must also be taken into consideration that the apparatus 

 can be made to fit various other types of analyses as required. 

 It is quite possible to use a larger mercury bath on the apparatus 

 and to use more absorption pipettes filled with various solutions. 



The accuracy of gas analysis in the apparatus of Polowzow- 

 Richter is scarcely less than that of the approved methods of 

 Bunsen and Doyere. With care the determinations of CO2 

 reach an accuracy of 0.15%, the oxygen determinations down 



' If further decrease in volume took place after the second explosion, % of the second 

 decrease in volume is still to be added to the above number. 

 2 Bunsen, R. he. cit. Pp. 24, 127 and 130. 



