( 16 ) 



of the compound, and that therefore the loci 



dvf' 



Vsf ■= and 



. Wsf = will interchange places on the left and the right of 



d^ 



the line of the compound. 



By means of equation (10) we understand now easily that the 



sign of the quantity r — - . IFs/ must be negative outside the locus 



- — . W,f = 0, and positive within it. 

 dv/ 



As connecting link for the transition to the PjJ'-lines we might 



discuss the TsT-Hnes; for this purpose we should then have to make 



use of the following equation (Cont. II, 106) 



rvj-' ovf . o.vf_ 



OV/ OVf . OWi 



dvf . d.vf 



Ö>1 dT 



By taking x constant we derive from this 



{dT 





or 



T 



dv 

 dT 



7 



— ihf)" 



V. 



sf 



I shall, however, not enter into a discussion of the F7-lines because 

 it is to be seen even without this connecting link, what the course 

 of the P,7Mines must be. 



If now for simplication we call 





Vsf = X^ and 





W^= X 



and if we indicate what the signs are of these quantities in the 

 different regions on the left and the right of the line of the com- 

 pound, and where these quantities become = 0, we get the following : 



left 



Xj — Xj — 



X, = 



right 



x, — o 



X. - ^. + V _ 



