48 PROBLEMS IN PHOTOSYNTHESIS 



The fundamental equations 12 and 13 are also valid for the differential ma- 

 nometer. 



Numerical example: 



The manometer vessel contains 270 ^1 cells. 



Vp = 7.000 ml 



Vg = 6.913 ml 



p^ = 10000 mm Brodie 



ao, = 0.03 



acoj = 0.87 



T = 20° C 



Hence, according to equation 7 



273 



Ko^= p ""i™' 



-» 



and 



Vg -y + ' FOico^ 

 Kco, = p mm^ 







SO that 



and 



6913 X 273/293 + 7000 X 0.03 „ . ., 

 ^o. = ^0000 = 0.665 mm- 



6913 X 273/293 + 7000 X 0.87 ^ ._ 

 Kca = —^TT^T^T^ = 1.25 J) mm- 



The values for Aq, and Acq, are calculated from equations 12 and 13. For 

 -y = — 0.8 and h = 60 mm Brodie after 60 min illumination, we find 



0.665 X 1.253 , .n . , 



- ^-^ = ^^ X 1.253 -0.8X0.665 = + ''■''' 



and 



^^ ^ 0.665 X 1.253 

 ^■^«^ = ^^ >< -1.253/0.8+ 0.66 -5 = " ^^'^ ^^ 



§ 19 The Two-vessel Method 



When the value of 7 is unknown, equations 12 and 13 do not suffice for 

 calculating Xq, and .Vco,, because they contain three unknowns. Measure- 

 ments with two vessels, however, permit the calculation of both gas amounts 

 (25, 26). The vessels must be different in size (Fig. 18) and therefore have 

 different vessel constants. However, in each vessel the same amount of cells 

 is suspended in the same amount of liquid. Over equal time periods the 

 values of %, and Vco, should be the same for both vessels. But since the vessel 



