( 580 ) 



tluvu has boen done up to now. 1 also pointed ont (loc. cit. p. 'J 5) 

 that already before nic Koktkww; has tried to find a finite expression 

 for the plaitpoint line, but has not fidly succeeded in this. His dis- 

 cussion extends after all only over the special case') b^^=b^—li^.^, Oi=aj 

 (but «15 := xa^"), whereas in my paper cited it was assumed in the 



discussion that b^:=^l>^, but that «i ^ (Vj(andai, = l/rt,ö,).KoRTE\VEG's 



paper is of the highest importance, specially with regard to the 



connodal relations, which are often so intricate, and to which we 



shall presently come back. 



The equation of the plaitpoint line once being derived in the above 



mentioned finite form, it was hardly any difficulty to derive also 



1 fdTA 

 for the expression -— — — on the side of lower critical temperature 

 T\ da; J, 



T p 



an accurate expression, in which only the quantities 6 =z —^ and jr =r — 



•' 1 Pi 



occur. In Van der Waals' paper mentioned by me in the paper 

 cited, again only the general differential equation for the expression 

 mentioned is given, (cf. (9) p. 89). 



2. Some important points are left for discussion. 



1^' The discussion of the transition case at the double point, with 

 regard to the shape of the spinodal lines etc; and the discussion of 

 the possibility of the 3'<J case (loc. cit. fig. 3). 



2"'' The treatment of the special case d^^l. 



3"' The different connodal relations in the three chief cases and 

 in the transition case. 



4"' The particularity of the c'Uf:p at R^, R^ and /?,' in the p/T- 

 representations of the three cases (loc. cit. la, 2a and 3a). 



5''' The question concerning the occun*ence of a minimum critical 

 temperature, and in connection with this of a ma.vinmm vapour 

 pressure. 



Let us in accordance with our last paper (loc. cit. p. 144) begin 

 with the fifth point. 



a. Minimum-critical temperature. 



In tills paper I derived the formula: 



1 fdT^\ 1 



"^^~C/-^-'/'^0-']- • ^'^ 



') Arch. Neéi-l. 24 (1891), p. 297, 324, 337 and 341. 



