CONNECTION BETWEEN BLOOD AND GASES 523 



air is 79 volumes of nitrogen, 20'96 of oxygen, and O04 of carbon 

 dioxide ; the total pressure is 760 mm. The tension of aqueous 

 vapour at 30 is 31 -5 mm., and must be deducted from the total 

 pressure, 760 31.5 = 728.5 mm. The partial pressure (p) of each 

 gas is as follows : 



Oxygen 



728-5 x " = 152 ' 7 mm< 



79 



Nitrogen = 728 -5 x =-^ 

 1UU 



Carbon dioxide = 728-5 



0-04 



- 0-3 mm. 



The absorbed gas (y) is calculated according to the formula : 



_a. h.p 



*"~7So~' 



in which ft =100 and a = coefficient of absorption given in the above 

 table for 30 ; thus the amount of oxygen absorbed is 



0-0262 x 100x152-7 



760 



= 0-526 c.c. 



The total amounts are : 



Oxygen in 100 c.c. of water 

 Nitrogen in 100 c.c. of water . 

 Carbon dioxide in 100 c.c. of water . 



0-526 c.c. 

 1-045 c.c. 

 0-025 c.c. 



The absorption coefficients of the different constituents of 

 blood can be determined by direct experiment only in the case 

 of those gases which form no chemical combinations with any of 

 the constituents. The data for nitrogen in all cases and for oxygen 

 in the plasma can be determined directly, but not for oxygen and 

 carbon dioxide in the blood or for carbon dioxide in the plasma. 

 In these latter cases Bohr has calculated the coefficients indirectly 

 from the absorption of indifferent gases, such as oxygen and 

 nitrogen in the case of the plasma and hydrogen in the case of 

 blood. The following are the respective values given by Bohr. 



