50 Larmor, Physical Aspect of t lie Atomic Theory. 



which is the type of formula usually assigned for the 

 ■equilibrium of a triple dissociation. When the amounts 

 ■of interacting materials are given, this formula determines 

 their distribution. 



If BC 2S\6. CA are very transient compared with AB^ 

 we have lla and in\b very small compared with n\c^ while 

 / and g are large compared with // if they take a sensible 

 part in the equilibrium ; then 



^A.B. C= (k, + k.^ + ^^3 — ^--y)ABa 



Ka b c+ n. Cj 



But if we suppose only five substances sensibly operative, 



say ABC, AB, A, B, C, the equations will be the (usual) 



binary ones, 



c.AB = h.A.B, k.ABC=?i.AB.C, 

 yielding 



kc.ABC^Jm.A.B. C, 



which is a different law of equilibrium, being the same as 

 if AB also did not occur. 



If A and B and C are identical, this latter law will 

 hold universally : if only A and B are identical, it need 

 not do so. Generally, the conditions for its validity are 

 that /, m, n should be very small, or else lla = in\b = nlc. 



The tliei-nwdynamic condition of equilibrium employs 

 conceptions and physical constants different from those 

 pertaining to this statistical view of Guldberg and Waage, 

 but at bottom connected and in ordinary cases leading to 

 the same results. If ;//;, in^, vi.^, ;//,2,... denote the quantities 

 of the different simple and compound substances that are 

 present in any phase, and A the available energy, 



IA = + ^x■^h?^^ + jj.^m,^ + + iJi.^„}ni^„ + 



And as the available energy tends to a minimum, under 

 the appropriate conditions, including constancy of tem- 



