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öf two separate parts. First that part that we might call vapour- 

 liquid binodal curve. The liquid branch of this part has a regular 

 course, but the vapour line branch has the well-known shape with 

 two cusps. The nodal line belonging to the cusp 7, has its other 

 extremity in the point 7, where the liquid branch tit this binodal line 

 passes through the spinodal curve. In the same way the two points 

 indicated by 6 belong together as extremities of one same nodal line. 

 The remaining part of the binodal curve forms a curve closed in 

 itself. For this part of the binodal curve the two heterogeneous 

 plaitpoints l\ and P, are in the first place of importance. The points 

 on the right and on the left of l\ lie in the stable region, the points 

 on either side of / J 2 in the unstable region. If we continue the branch 

 on the right of 1\, and pass through the spinodal curve in the point 

 a, then to this point as an extremity of a nodal line belongs another 

 point (t as the other extremity of this nodal line, and there must 

 again be a cusp for the binodal curve for this second point a. In 

 this second point a the binodal curve returns again to higher value 

 of ,/', and if it then meets the spinodal curve in the point indicated 

 by $, another point /? belongs to this, at which the right branch has 

 a cusp. From this point the remaining part of the binodal curve 

 has only points in the unstable region, and the points lying between 

 the two points ji are extremities of nodal lines which approach each 

 other and coincide in l\. 



To find the 12 points in which this (/-line cuts the binodal curve, 

 let us apply Maxwell's rule to that portion of the jp-figure with the 

 branches a, l> and c, and determine the points denoted by 1. Let 

 us also add the branch <l, then the equality between the areas above 

 and below the straight line would be disturbed, if the same straight 

 line is retained, i. e. in this sense that the total amount of the areas 

 above the straight line would be too large. From this follows that 

 we must trace the straight line higher. For the points of the binodal 

 curve which are determined by the combination of a with </, the 

 pressure is, therefore, larger, while, as the figure shows, the volumes 

 are both smaller than those of the corresponding points 1. The points 

 determined by this combination have been indicated by 3. If we 

 now also add the branch e, the pressure must again decrease. Then 

 we determine .the points denoted by 2. It will presently appear that 

 the pressure in 2, though it is diminished, is still larger than in 

 the points '1. By means of the combination of h with (/, both branches 

 in the unstable region, we determine the points 4 ; and after addition 

 of the branch e the points 5, which must have lower pressure than 

 the points 4. Finally the combination of c with e remains. Now 



