( 742 ) 



the spinodal curve only in two points. If, however, the temperature 

 chosen should lie above {Tic), the q-\ines of still higher degree than 

 of that, passing through the vapour-liquid-plaitpoint, will no longer 

 cut the spinodal curve. 



And finally one more remark on the spinodal curve, which may 



d 2 \\> d*y 



occur in the case of fig. 8. By making the line — = and 



///• 5 



dx'- 



If this should be the 



d'tp d*\p 



= intersect, we have a region, in which both — — and — — is ne- 

 ar dx 



gative. In such a region the product of these quantities is again 

 positive, and it may become equal to I y— 



case, it takes again place in a locus which forms a closed curve. 

 Within this region there is then again a portion of the spinodal 

 curve which is quite isolated from the spinodal curve considered. 

 With regard to the />- and ^/-lines this implies, that there both 



_ an d — is negative; and so that contact is not impossible. Such 

 dxp dxg 



a portion of a spinodal curve encloses then a portion of the i|> 

 surface which is concave-concave seen from below. If we consider 

 the points lying within the spinodal curve as representing unstable 

 equilibria, the points within this isolated portion of the spinodal 

 curve are a fortiori unstable. The presence of such a portion of a 

 spinodal curve not being conducive to the insighl of the states which 

 are liable to realisation, we shall devote no more attention to them. 



It appears from this description 

 and from the drawing (tig. 8) 

 that in this case the spinodal curve 

 has a more complicated course 

 than it would have if the curve 



— = did not exist. It has 



a portion on the liquid side 

 in which it is forced towards 

 smaller volumes. There is, however, 

 no reason to speak here of a 

 longitudinal plait. We might speak 

 of a more or less complicated 

 plait here. But we shall only use 

 the name of longitudinal plait, 

 when we meet with a portion 

 Fig. a that is quite detached from the 



