234: 



.Dr. R. D. Kleeman 



equal 

 good. 



to the observed ; the agreement, however, is not very 



The equation may thus be used to obtain a rough 



idea of the value of the coefficient of diffusion of two gases 



into one another. 



Table IV. 



Diffusion of gas 



takes place from 



right to left. 



H 2 — 2 



Coefficients of diffusion. 



Observed. 



Calculated. 



Calculated by 

 another 

 formula. 





722 



642 

 556 

 480 

 180 

 161 

 160 

 159 

 142 

 089 



•948 

 •940 

 •724 

 •668 

 •166 

 •125 

 •136 

 •159 

 •136 

 •089 



•871 

 •904 

 •723 

 •655 

 •116 

 •160 

 •125 

 •151 

 •125 

 •089 



h; —co 



H 2 — C0 2 



H., — S0 9 



CO-Oo 



0, —CO, 



CO —CO." 



cit 4 — co; 



Air —CO] 



N 2 0— CO., 









The formula for the coefficient of diffusion used in this 

 paper is the one usually given in treatises on the kinetic 

 theory of gases. Maxwell has given another formula for 

 the coefficient of diffusion based on the assumption that the 

 force of attraction or repulsion between two molecules varies 

 inversely as the fifth power of their distances of separation. 

 This law, the writer* has shown, holds approximately for 

 distances of the order of the distances of separation of tbe 

 molecules in a liquid, and the attraction is further propor- 

 tional to the product (Xm\ /2 )(Zm2 2 ) . Maxwell's equation 

 accordingly becomes 



where K : is constant at constant temperature and pressure. 

 The values of B 12 obtained by this equation are given in the 

 fourth column of Table IV. The values of S I2 calculated by 

 these two different formulae agree better with one another 

 than with the observed values. On the whole both agree 

 equally well with the facts. 



* Phil. Mag. May 1910, p. 783. 



