( 67 ) 



which equation may be written in the following form: 



UJ 



ilr" ill" V tl.nli 



Y 





From this form we sec that I is positive in the unstable region 



V'-V 7 

 d*ip ,/•-> filp\ 



only when - — is positive. If - is negative, then ( — is again 



i/,« 2 r/,r- \dvjq 



negative in the unstable region, and when the g-line intersects the 



d*ip f,Ip\ 



curve = 0, — = oc. In fig. '16 the course of /> as function 



dar \ 'IrJ 



of v when this g-line is followed, lias been schematically represented. 

 P 



Fig. 16. 



Now we have to examine how many points of the binodal line 

 lie on this g-line. For this discussion I shall represent the branch 

 right of point i by a; the branch between 1 and 2 be then the 

 6-branch etc. The number of times that Maxwell's rule can now 

 be applied, is equal to the number of combinations in two of 4 

 quantities. Thus branch a could be combined, not with branch b, 

 but with branches c, d and e. The branch b may be found combined 

 with d and e. And finally branch c with e. We do not mean to 

 say that the application in those 6 cases is always actually feasible. 

 This will be discussed presently when we discuss other j-lines. Bui 

 for the gr-line chosen here, it is really possible to trace those 6 

 Maxwell lines. And then this q-Vme must cut the binodal curve 

 '12 times. These 12 points of intersection are to be found in fig. 17. 

 In this figure the q-Yme has the shape of fig. 8. It intersects the 



