Physics. — ''On the Course of the Values of a and b for Hydroqen 

 at Diferent Temperatures and Volumes" . III. By Dr. J. J. van 

 Laar. (Communicated bj' Prof. H. A. Lokentz). 



(Communicated in the meeting of Febr. 23, 1918). 



Continuation of § XVI. 



The factor by which the double integrals (7) are niultipJied, now 

 becomes, witii n^=N'.v: 



I mia-^ XMN = \X^ ^Ns' X MN X "- X - , 



s V 



i.e., as I jtNs'^ ^ 4/« ^ {b,,)^ , MN = <t -. 



a' \ a' \ 



è X (b,)^ >: « X - X - == to X ^ X - . 



With omission of 1 : v we get, therefore, for the constant of 

 attraction a: 



when also for F{r) and — F' {r) their valnes according to (8) and (8a) 

 are substituted. When to abbreviate we write /Mbr .v' : (a'— .y'), the 

 above becomes : 



90 « • ÖQ a 



^^ 2a' r rr drXsmddd rr 



a = w X ~. — -. _ + ii'id. 



in .which, therefore, a> = ^ X U^ii)^, X «. 



Let us first discuss the first integral referring to all the molecules 

 that pass the molecule which is supposed not to move, without 

 coming in collision with it. We may write for it: 



90 a 

 _ rr drXsinddd 



.(7") 



' J J r[/a^ 



eos^ <9— (a^ — r')(l— Fr/) 



As was already remarked above, the above calculations only hold 

 for temperatures above a certain limiting temperature 7\, defined 



