( 842 ) 



That what we have called hidden plaitpoints, can never exhibit 

 themselves, requires no explanation. That what in general we have 

 called realisable plaitpoints, need not always show themselves, may 

 indeed be assumed as known from the former thermodynamic con- 

 siderations about the properties of the ^-surface - - but yet it calls 

 for further elucidation now that we examine the properties of stability 

 and of realisability by considering- the relative position of the p- and 

 the g-lines. We shall, however, only be able to give this elucidation, 

 when by treating the rule to which I alluded in the beginning of 

 this communication, we have also indicated the construction of the 

 binodal curve. 



To get a clear insight into the critical phenomena for the case 



that for mixtures between two definite values of x the critical point 



(Pfp . _,. . 



falls in the region in which — is negative, we must again distinguish 



two cases; viz.: 1. the case that already at T= T&, the curve 



d *V ^ n 11 I A 4. rp rp 



partly projects above — =0, in which case already at 1 = 1 ^ 

 the two plaitpoints 1\ and I\ are found, and 2. the case that at 

 7'= Tb the curve z — 0, lies unite enclosed within - =0. In 



ft l 7 9 



d.v'- 



dv 



£M=o 



cUdv 



Ë-° 



■-&< 



of T^>Tkj the top of 



di 



fig. 13 the second case is 

 represented. Now if for values 

 dp 



./-if 

 d^ 



there must have been contact 

 of the two curves at a lower 

 7'. and intersection at a higher 

 T. As long as the two 



does fall within 







() 



curves do not yet touch, the 



spinodal curve is little or 



not transformed, and no other 



plaitpoint is .to be expected 



as yet than the ordinary 



Fig. 13. gas-liquid plaitpoint which 



dp 

 lies at smaller value of x than the top of — = 0. If the two-curves 



dv 



intersect, the plaitpoints P l and P a have appeared first as coinciding 

 heterogeneous plaitpoints, later as two separate ones. Naturally the 



