( 13 ) 



• 



of the compound also there it is negative outside, positive inside 

 the first mentioned locus. 



Before proceeding to my real subject, I shall, for the sake of 

 completeness, first call attention to the fact that the spinodal curve, 

 for which the equation : 



d'xb \d.rdvj ö'5 



^ — ^^- — - = or — - = (J (7 1 



p 





holds, lies entirely outside the locus r — = 0. Van der Waals M 



proved this in the following way : 



On the spinodel curve and - — must both be positive, and so 



/d'xpY ^ ö> dp 



also r-^— . As T—- =: — V- IS positive outside the line for which 

 \0:cdi:J ov^ ov 



- — =z 0, the spinodal line will alwavs have to lie outside the curve 



^ = 0. 



Or' 



That the spinodal curve which coming from the left, runs between 



the lines — — . Vg/ =z Q and - — = 0, cuts the line for -— 



Vs/=0 on the left of the line of the compound in two points q^ 

 and q^ which will be discussed afterwards, follows from this, that 



d^xp d^xb 

 on the line of the compound - — . Vsf=^ coincides with = 



and that the line - — - alwavs lies within the spinodal line, whereas 



drf 



on the riglit of the line of the compound - — . Vg/ = lies within 



Ovf' 



ö> 

 the line - — = 0. 



dv/ 



When we start from the maximum temperature of sublimation, 

 we get now i',.i'-lines which have been indicated by T^, 7\, 7\ and 

 T^ in fig, 1 for the equilibria between solid-fluid according to the 

 equation ') 



ö> a-iL'"i 



i^^s-Vf)^-^-\-{.Vs-.vf)^\ 



•^ ■ ■—. ... (8) 



dv/_ 



dxf d'lp 





•) loc cit. 



2) These Proc. YI, p. 489. 



