(751 ) 



\/p. 



i/p.j 



das. 



dx. — 



dp J h om ) 



\dp J hom \ 



or 



fdv \ | 



- y - =(1-//) 



V' /'J /iet I 



+ y j 



Now the factor of 



~v V, 



dr. 

 d.v. 



i/p. 



das^\ /V/v, 

 dp J bin \d/> Jh, 



+ 



«1— *1 



d.v, 



x Jp\ V d P /bin \dp J / W m 



dp 



d*$ 



dv\ 



- =(1-2/) 



dpjhei 



<n 



+ 



y 



dXi*/p,7\ d Pjbin 

 8 )p,T\dp J bin \dp Jh 



/d.v' . 

 — — , and we find: 



+ 



(1) 



d.V 2 *Jp ,T\dp J U„ \dp J horn 



If we consider the beginning of the condensation, and so y = 1, 

 the above equation becomes : 



\dpjhei _ \dx 2 y P ,T\dpJ bin \ dp J kom 



in which we must put v, = v and x, = x. It appears from this 

 equation, that never - 



dv\ fdv\ 



— = — I — , and that there must 



dpjhet \dpJhom 



dv dp 



therefore be a leap in the value of — — or of — at the begin- 



dp dv 



ning of the condensation, unless there should be cases in which 



d 2 C,\ /<&eV 



— I I ~ I i s equal to 0. The only case in which this is so, is 

 dx /P,T \dpjbin 



/dp\ fdx\ 



in the critical point of contact. There — = °° and so — = 0. 



\dasjbin \dpjbin 



But then there is properly speaking no longer condensation, and the 



empiric isotherm has disappeared. We might think of a plaitpoint, 



/d*$\ fdp\ 



because f - =0 in it, but on the other hand — 



\d* % Jp,T \dvjbin 



dx\ fd%\ (ox 



— =oo there. If the limiting value of — - I — 

 dp J bin \ da '' Jp,T\dp/b 



d% 



- and 

 or of 



(l,i 



P,T 



dpY 

 da Jan 



is sought, we find by differentiating numerator and deno- 



