Mi; J. S. TOWNSEND ON Till! DIFFUSION OF IONS INTO GAM-> 



151 



in the two gases cannot be attributed to a greater rate of recombination of ions in 

 hydrogen, as other experiments show that the ions in hydrogen recombine somewhat 

 slower than the ions in oxygen. 



Another set of 12 tubes were therefore made, 4 centims. long, and of the same 

 diameter as the tubes T,, and substituted in the apparatus shown in fig. 2 instead of 

 the tubes T,. A series of experiments were made, and values of y were obtained 

 which gave the ratios of the conductivities after the gas had passed through tubing 

 4 centims. and 1 centim. in length. The corresponding values of K were obtained 

 from Curve II., Section I. In correcting for recombination in these experiments it is 

 necessary to take into account the recombination in the tubes 1 centim. long. 



The results obtained from experiments with dry hydrogen which contained 1 '6 per 



cent, of air, are : 



K = "117 for the positive ions, 

 and 



K = '181 for the negative ions. 



The coefficients of diffusion in a mixture containing 1'8 per cent, of air, 1*5 per 

 cent, of water vapour, and 967 per cent, of hydrogen are: '121 and '134 for the 

 positive and negative ions. 



These results show that the rates of diffusion in hydrogen are 4 '3 times as great as 

 the rates of diffusion in air. In order, therefore, to obtain the coefficients of diffusion 

 in pure hydrogen at atmospheric pressure, the above determinations must be increased 

 by 3 '3 per cent, for each per cent, of air in the gas. 



Applying this correction, we obtain the following values for the coefficients of 

 diffusion of the ions into hydrogen : 



K = '123 for positive ions in dry hydrogen, 

 and 



K = '190 for negative ions in dry hydrogen. 



The corresponding coefficients for moist hydrogen are : 



K = '128 for positive ions, 

 and 



K = '142 for negative ions. 



The coefficients of diffusion for the four gases which were examined are given in 

 the following tables. 



TABLE III. Coefficients of diffusion of ions in dry gases. 



