( 752 ) 



minator twice with respect to so: 



'dTV /dT\ /d*? 



' P T _ [dx'JpT _ \dx*J Pt T 



dp\ " 2 (dp\ S£p\ ~ 2 fd*p^ 



As - ) must always be positive, also I J will always 



>/hom V UP J het 



(IX J l)l n \«'l ; y//i')i \dx J bi n \dx J l,i n 



In a plaitpoint, besides — also I - - 1 =0, but -^- 



will have a value differing from 0, and so there is a leap in the 



dv 



value of — in a plaitpoint too. 



dp r 



dv\ 



dp, 



( dr\ ( dp\ ^ f dp\ 



be positive and larger than or ]>( -J . 



V dpJ kom \ dvjhom V dvjhct 



At the beginning of t ho condensation the empiric curve will ascend 



less steeply with decrease of volume than that for homogeneous 



phases. 



• f dv \ ( dp\ 



there are cases in which — — = oo, or =0. 1. 



\dpjhet V dvjhct 



on the sides, so for x = and a? = l. Then ( — - ) is infinite, and 



/ MET \ 

 is represented by the principal term — I. 2. if on the binodal 



dx dp 



curve — - is infinite or — = 0; this takes place for those mixtures 

 dp dx 



which behave as a simple substance. 



If in equation (1) we put y = and i\ = r and x 1 = x we could 



derive the same conclusions for the end of the condensation. 



fdp\ fdp\ 



1 he relation between — — and — \ ~r ) at the beginning 



\dvjhet \dvJhoin 



and at the end of the condensation, could be immediately derived 

 by applying the equation : 



fdv\ fdv\ 



dv — hr d P + \1~) dx 

 \dpjx \daj p 



both for the surface of the homogeneous phases and for that of the 



/"dv 

 heterogeneous phases. If we then take into consideration that 



dx , p 



v„ — i\ 



on the heterogeneous surface is equal to - — , we find : 



tl' n tl/-i 



