( 84 ) 



JPhysics. — ''On the soUil sfiilc." VII. (Conclusion;. By J. J. vaK 

 Laak. (Communicated by Prof. H. A. Lorentz.) 



30. We shall examine now to wijat modifications some formulae 

 and results are subjected, when not tiro simple molecules, but 

 several, e.g. n, associate to a com])Ound molecule. 



In the first place the formula for /i, the degree of dissociation of 

 the compound molecules. Now the calculation of I (These Proc XI 

 p. 767 — 770) is modified as follows. 



The condition of equilibrium : 



— jUi + w ftj = . . (a) 



is reduced to : 



(— CiH-nCj— - r h'*T— + RT{-lopc,-{-nlogc.^ = 0, 



|_ o/ij on, J 



after substitution of the values for »<, and ii.^ (sec |). 707 loc. cit.). 

 In this equation li' = j pdv — pv — RT 2£n^ . log :£n^, Cj, C.,, n,, ?<,, c^ 

 and c^ having the known meaning (see p. 767). Further: 



d^ on, d{i on, rf,i dn, on, 



because n, = 1 — ,^ and n.^ = V. ^^ l'»^^t the equation of e(|uilibrium 

 passes into : 



5<>' c n 



(— (\-\-nC,) - ~ + RTlog ^ = 0, 



or into 



because 



n, 1 — i? n, n^ 



1 «^ + n, 1 + 0*— 1) i? - n, + n, 1 ^- (n— 1) ,? 



Now the value of -r— may be calculated by means of the equation 

 ü3 



of state. From 



(1 -f (n-l),i)/27' a 



P = 7 , (^) 



V — v' 



follows: 



a 



i' 



V 



pdc = {l -\-{n-l)i^)RTlog (v^h) -f 

 because we know that the quantity ,i must be kept constant during 



