( i<ii ) 



may be found. If is Ciisily found from the equation, occurnng in 

 Conl. II p. 146, sliglitly reduced, viz : 



MRT ^^ if -r I i 



From tiiis form we derive, keeping ,i\ constant: 



_^ ^_ dT d{iij,^ — .v, fig-i— 1) 



pdT r"~-^_^.^_^,.^^//,. dT 



for which we may write: 



dp 1^ _ ^ (/.u'fi d (ft,^ — .7?^ ft'aj ) 



r/i — ''"2 TTTi r 



dT ' dT 



, and for —— we get the walue 

 d.l 



Hence : 



fTdp\ ƒ ( rZ7),l 



\pdJ J.C, ^ \ d.v^ ) 



Multiplying the second memt)er by }[RT, we (Ind /r,,. For v\^ 



we find then 2 terms, the first MR f T,, representing the heat of 



evaporation, Avhen the mixture x^ evaporated as an unsplit substance, 



and therefore the vapoui- }»liase would have the same concent ral ion 



/ dJ\ 



as the li(|uid [)hase. The second i)ai't ' , O*'.^ — '''■i) 1 — denotes the mo- 



J d.i'^ 



ditication, which is the consequence of the circumslaiice, that the 



va[)Our phase has another concentration than the licpiid phase. This 



modification can be \'ery considerable in certain cases, viz. when 



A\ — d\ is very large. If 7/^. should (le|iend linearly on ,i\ then 



'dJ\. 

 Th, + (.I'a — .vj = 7V, and for 7/,-, we miulil write in that case, 



denoting the components of the mixture by a and li: 7/,,= 7/.- 



Trdp\ T dp" 



(l-.rJ+7V,.v (Cont. II, p. 155) or - -M = (l-^,) ^ -^ + 



" j' \dJ J.V, rad J 



-f- .'•., — — ;. Then ir.^^ = Ma Va (1 —'^'2) + Mh I'b -I'-z, •^"•' "'<-' process 

 pb dJ 



of mixing in the liquid state will lake place without heat of mixing. 



