J7Ö 



consequently is the maximumtemperatiire of sublimation Tk of the 

 substance F. 



Now we will deduce in another way the saturationcurves under 

 their own vapour pressure of F. The conditions of equilibrium are : 



dZ dZ, dZ dZ, 



These conditions follow also from the equations 1 (II) when we 

 equate herein a = Ö and .i\ = and when we consider Z^ as inde- 

 pendent of .r,. We put 



Z = U -\- RTx log X (18) 



The three conditions (17) pass then into: 



Ö/7 . bU 



C7-.r-^--(y-/V)-- 

 ox oy 



Z-{v,--rl) 



dZ^ 



RTx-^ 



$=0 . 



dU dZ, 



dy d?/, 



i = 



(19) 

 (20) 

 (21) 



From this follows 



[xr -I (.y-r/) ,s + 7^7'] dx -f [...s f (y-) t] dy 

 OF . OF 



F 



■'^■a7-''"-^^'d^ 



tZP 



{y X— i"') h 'hi X 



^i~^-:^) 



ÖF^ 



rfP 



ÖP; ÖF\ 



— K 



sc?,t' -f tdy—t^ di/^ — I - — UP . , 



\dyx dyj 



With the aid of (23) we may also write for (24; : 



* r . - OF ' 



{y,~ ■!) sdx + (y^- V)/ ^?y — T , — fi/,~/>') — — V 



dP 



(22) 

 (23) 

 r24) 



(25) 



so that for the relation between r/,r, c///, c/yj, and c/P we shall consider 

 the equations (22\ 23), and (25). 



In order to examine if a point of maximum- or of minimum- 

 pressure is possible on the saturationcurve under its own vapour- 

 pressure, We take (23). From this follows dP=0 when 



^: = /^ (26) 



In order lo examine if the pressure for this point is a maximum 

 or a minimum, we develop (20) further into a series; when we 

 equate herein //, =r •', we find : 



