747 



which 1^ deci-eiises anil reversally. We see that this is in agreenieut 

 with the direction of the arrows in fig. 5 and 6 (XI). 



If it is desired to know the influence of a small change of 7' 

 on the position of the saturationcnrve under its own vapour pressure 

 going through H, we must also include terms with clT in the 

 previous expansions into a series. Now Ü=Z— It 7]vlo(/.v iUeref ore, 



A IT 



—-= — H — Rv log X, therefore in the point H {x = 0) itself 



dT 



dH 



In the right member of (12), therefore, must be added — dT 



dij 



and terms with S^dT and ijdT; in the left member ^' dT. 



In (13) must be added {H—ii„)dT; in (14) [H—iy)dT; in order 

 to distinguish the coordinate % the entropy of the solid substance 

 F is indicated by t]v 



In the first member of (16) must be added: (y, — ^) {H — ii,)dT; 

 in the second member {y — ^) [H^ — ^.). 



From (13) follows : 



'" = ("-?)'''+••• 



from (14) 



/ dV;\ 



As we must substitute these values in (16), it is apparent that 

 we may neglect the other terms. As 



(i?-^:) H + {y-y) lu + iu-^) H, = (y-^) ^ 

 we obtain : 



AW 



% = a.dr-+{y-^).-^.dT 



2ET\y-^-{y-^)^-^^ 



or, after deduction : 



/ ^\ dH A IF 

 2Rr.K\^--j% = t{y-y,)^^.dP^ ~ dT . . (27) 



and: 



/ 5\ t^iy-y,) dH LW 

 2RT.K[\ 1^= ^/^^. .ir .dT . (28) 



dF\«VP» 



From (28j it follows that not only the saturationcurve under its 



