( 231 ) 



TT =z 1 the branch AR^Cq would coincide with AB (;ü = b). There- 

 fore the special value 4,44 has been replaced by 6*^ (the value of 

 6 in Q) and the value 9,9 by 6*^, (the value of & in P). 



Of the curve which separates type II from type III we know as 

 jet only the points F and (2 (see fig. 1) and the further course of 

 this line is still quite unknown, for which reason we have denoted 

 it by a dotted line. 



In any case the investigations, described in the Arch. Teylerhave 

 proved, that this very abnormal type III is possible for mixtures of 

 normal substances. If the critical pressures of the two components 

 are the same {n == 1), then we meet with this type when 6 lies 

 between 4,4 and 9,9. The critical temperatures must therefore lie 

 far apart, but not so far (see fig. 1) as would be necessary for the 

 appearance of type I. 



We shall once more emphatically point out that the numeric results 

 of our investigation will naturally be modified, when b is not assumed 

 to be independent of v and T, or when one of the two components 

 should be associating substances. This will cause the types III and I 

 to make their appearance earlier than has been derived above (i. e. 

 with lower values of S with for the rest equal values of tc), but 

 that qualitatively everything will remain unchanged. This appears 

 already from the fact that the substitution of the quite general assumption 



^1 \. ^a fo^' tlie simplified assumption b^ = b^ (in the first paper in 



the Arch. Teyler) has made no change is the existence of a double 

 point in the plaitpoint line with certain corresponding values of 6 

 and jr, and that also the calculations for the limits of type III 

 (in the second paper in the Arch. Teyler) may be carried out for 



the quite general case b^-^b^. So the phenomena remain qualitatively 



the same for very different pairs of values of b^ and /;,, and will 

 therefore not change essentially either, when one delinite pair of 

 values, holding e.g. for the critical circumstances of one of the com- 

 ponents, is subjected to changes, whether by association, or by other 

 causes, when v or T change — no more as e. g. the critical pheno- 

 mena for a simple substance will essentially change when b is no 

 longer constant, but is supposed to be dependent of v and T, or 

 when that substance forms complex molecules. 



The longitudinal Plait. 



2. In former papers it has been demonstrated that in the neigh- 

 bourhood of Co a minimum plaitpoint temperature makes its appearance 



