Ml; .T. S. TOWNSKND ON THE DIFFUSION OF IONS INTO OASES. 13'J 



Hence, 



'1321 T-U -0'W> 44-*WC: 



R - " " 



0926 44-50 



This formula holds for gases in general, when the gas which is being absorbed is 

 present in small quantities. This restriction is necessary, since the effect of gravity 

 would disturb the distribution of pressure given in equation (8), especially when the 

 gases A and B differ much in density. 



We therefore conclude that, when two gases, A and B, are mixed together and 

 passed along a tube, the surface of which absorbs A, the ratio of the quantity of A 

 which emerges to that which enters is 



7-3Ulti 44-MK 



4 [-1952 e"^^ -f -0243 e~~&v~ + Ac.], 



where a is the radius of the tube, z its length, K the coefficient of interdiffusion of 

 the gases A and B, and V the mean velocity of the gases in the tube. 



The effect of the velocity being greater at the centre than at the surface of the 

 tube, is to increase the quantity of A that comes through the tube with B. This can 

 be seen* by comparing the formula (10) with the function 



. (2- 



12-404)" K: (VUPK: 



+ ? :L_ + 



(5-52) 1 



which is the ratio of the quantity of A coming through the tube to the quantity 

 entering, calculated on the supposition that the velocity of the gases is the same at 

 every point. 



If a gas, with ions uniformly distributed in it, has a conductivity c, after passing 

 through a tube of length l t , and a conductivity c z after passing through a tube of 

 length If, we see from Equation (10) that 



7-aiK/, 44 SK , 



(11). 



T'llji, 44-MCt, 



~ 



8. When the iouization is produced by Rontgen rays the ratio Ci/c, can be easily 

 determined for most gases when /, = 10 centims., l t = 1 centim., a = 1'5 millim., 



7'31K/ 

 and V about 100 centims. per second. Letting d/Cj = y, and -^-, v ' = *, the values 



of y corresponding to a series of values of x were found, and a curve representing the 

 connection between x and y was drawn. The part of this curve which includes the 

 values of y, which were obtained experimentally, is given in the first diagram, and 



from it the values of ^ ^ ' can be immediately found. 



* JOHN S. TOWXSEND, ' Phil. Mag.,' June, 1898. 

 T "J 



