( 58J ) 



Pilt (ing- L <0, we get: 



s< ^" 



01' 



4jr \/üt 



e < — (3) 



This gives the following synopsis: 



^ = V,s V:. V, V, 1 4 9 16 25 



'9<V. 1 ^. 2 1 lv„ 1"/» 2-A„ 2'7„. 



^ always being assumed >1 (7'j is the lower of the two critical 

 temperatures), a minimum critical temperature can only occur, when 

 .T, i. c. (he ratio of the two critical pressures ^ '/le- 



If jr = '/,, this takes place for nil values of 8 ; if .t = y^, only 

 for values of & between 1 and 2; etc. etc. (For .t ^ 1, a minimum ' 

 occurs in the above series of extreme values for 6, viz. é':=1). 

 Now in by far the most cases jt will probably lie between 1 and 4, 

 so that & will always have to be quite near J , if a minimum critical 

 temperature is to be found. 



Let us take as an illustration tiio normal substances C,H, and 

 N3O, investigated by Kuenen. There 



74 ' 273 + 36 

 rr = — = 1,65, j/.-r = 1.29, f) = — =1,00. 



45 273 + 35 



According to the above rule, 8 has to be smaller than 1,04, if 7', 

 is to be minimum. This is the case here. Kcenen found really a 

 mininuim value for 7!r. 



We also call attention (0 the fact that when /i^ =z b^, so Ji=:8, 

 no value of (^ exists^] satisfyingthe ineipiality (3). For 8=zjt = 1 {a^=a ^, 

 hy = 6.J the two members are equal, and the line of the critical 

 temperatures is a straight line. The foregoing is in perfect concordance 

 with what we have derived in a previous paper with regard to this 

 point (loc. cit. p. 43). 



Also in the special case jr = \ evidently not a .single value of 

 8 exists greater than 1, which satisties (3). But in the case 8 = 1 

 there is nhnmjs a value of jr conceivable, yielding a minimum for 



