﻿Kinetic Theory of Adsorption, 



693 



Williams * from entirely different assumptions, and ean be 

 tested with the help of: Williams's calculations of the 

 measurements of TitofF, Homf ray, and Chappuis. Keducing 

 the equation to his units (adsorption a. in c.c. of gas at 

 N.T.P., pressures in cm. of mercury), we obtain 



loo- « = log (2-988 . 10 8 . f ; -0-4343 

 = A — A^ 



(14) 



The agreement found is very good, as is shown in the 



Table I. 



following table : — 



' Number of 

 Observations. 



Mean divergence of observed 

 results from those calculated 



by equation (14, ^'i-S- 



Nitrogen (Titoff) 



Methane (Homf'rav) ! 



Carbon monoxide (Homfray) ... 



Carbon dioxide (Chappuis) up to 

 an absorption of 40 per cent.! 

 saturation, (excluding one 

 reading) 



10 



49 



09 per cent. 



06 



0-8 



08 



7'0 per cent. 



4-4 



7-0 



Above 40 per cent, saturation, as might be expected, the 

 approximation (14) ceases to hold exactly. 



I have also applied relation (14) to some measurements of 

 Schmidt t on the adsorption of vapours of charcoal; these 

 observations are not very precise (they do not lie evenly 

 on any smooth curve) , but for fairly low concentrations 

 reasonable agreement is found. In rig. 1, log a./p is plotted 

 against a for three series. 



From the experimentally determined values of the 

 constants A anJ A l5 values can be obtained for f, a, and N . 

 These are shown in Table II. The values for a are positive 

 small quantities, and, moreover, for the four gases the relative 

 magnitudes are as would be expected, small for the inactive 

 nitrogen, which cannot saturate much of the field of force, 

 intermediate for methane and carbon dioxide, and largest 

 for the unsaturated carbon monoxide. The values for f, 

 which is a measure of the relative stability of the molecules 

 on the surface, also follow the same sequence, the inactive 

 gases having the shortest life on the surface. Finally, the 



* A. M. Williams, Proc. Rov. Sue. A. xcvi. p. 287 (1919). 

 t Schmidt Zeit.f. Phys. ('hem. xci. p. 115(1916). 



