46 PROBLEMS IN PHOTOSYNTHESIS 



or 



. , 43300 _^„.„ 



1 Ml quanta = ^^.^n ^ in3 = 0-0019 ca. 



22400 X 103 

 According to equation 2, the general equation is 



1 , 12.8 , 



1 ^1 quanta = — r — cal 



A 



§ 18 Theory of Manometry 



In respiration almost as much COo is produced as O2 disappears, while in 

 photosynthesis nearly as much CO.2 disappears as O2 is produced. Warburg 

 succeeded in overcoming this difficulty by adopting a modified technique 

 (19). As already pointed out, there are two phases in the manometer vessel: 

 the liquid cell suspension and the overlying gas phase. Oo and CO2 are 

 soluble to different extents in the liquid phase, much more CO2 being ab- 

 sorbed than O2. For this reason, it is possible to measure the resulting pres- 

 sure changes with a high degree of precision. 



Imagine a manometer vessel pardy filled with a liquid which produces a 

 gas. As the volume is kept constant, the pressure increases and the problem 

 now is to calculate the amount of gas produced from the change in pressure. 

 The temperature in the vessel is kept constant. The magnitudes are : 



P = pressure before the experiment 



P' = pressure after the experiment 



h = pressure change 



IV = volume of the liquid phase in ^1 



]\] = volume of the gas phase in ^1 



T = absolute temperature 



a = absorption coefficient of the gas produced in the liquid phase 



Before the experiment the amount of gas at ° C and 760 mm Hg in the gas 

 phase is 



P 273 



760 T 



ValA 



and in the liquid phase is 



760 ^'^-^ ^^ 



In both phases the amount of gas is 



^/27: 



760V T 



^ (^ Va + f>) Ml 



and after the experiment 



760 



'-^{^^V. + V,a) ,\ 



