(53) 



1148 



under its own vaponrpressiire and its corresponding vapourcuive. 

 We put in the formnlae (2)- (4) (VIII) «'=--« and ;:?'=/?. We 

 then may write these : 



(., _ a)r -4- {y-^)s\ dx 4- \{x -a)s + {y --^)t] dy = AdP—BdT. (52) 



r= {A 4- C) c/P-(5 A D)dr \' ' 

 {v-v)dP-(ri'-n)dT=0 (54) 



Let lis first tal<e tiie substance F. The /^, 7kliagrani of this 

 snbstance was already discussed formerly and is drawn in tig. 

 3 (III) and 4 (IV). In fig. 1 arK represents the sublimationcurve, 

 Fd the meitingcurve and KF a part of the limitcurve mKFM of 

 the substance F. We find also in fig: J the y-*, T-diagram of the 

 snbstance F' ; herein <(' vK' is the snblimationcurve, Fd' the melting 

 curve and K' F' a pait of the limitcurve m' K' F' M' of the substance F' . 



The two sublimationcurves touch one another in r ; consequently 

 in r the equilibrium FA;- F' -|- (r occurs, wherein (r has the com- 

 position F =z F' . Therefore from r also a curve rli proceeds, which 

 represents the equilibrium F -\- F' . This curve may proceed from 

 r as well towards higher as towards lower temperatures ; in fig. J 

 the first case has been assumed. It is apparent from the position of 

 the diiFerent curves that we have assumed v' ]> v, r;' > ri, V ^ v 

 and Vyv'. 



dP 



From (54) it follows that - for the equilibrium F^F'-{-L-\-G 



dT 



and F^F' is the same. This is also apparent without more 



explanation : when we remove \'iz. the liquid and the gas from 



M, 



\ 



iMg. 1. 



^F 



