196 Dr. J. P. Kuenen on the Condensation and Critical 

 Table XVI L 



N 2 0-C 2 H 6 . 



X. 



2 ' 6 27 V 



T c - 



0-18 

 0-43 

 0-55 

 0-76 



302-8 

 2990 

 298-7 

 300-5 



3028 

 29905 

 29905 

 30085 



C 2 H 3 -C 2 H 6 . 



0-27 

 0-41 

 0-51 

 0-61 

 068 



296-7 

 2931 

 293 

 2936 

 294-8 



296-8 

 294-15 

 293-0 

 293 8 

 296-75 



C0 2 — C 2 H 6 . 



015 

 0-30 

 043 

 0-50 



296-1 

 291-8 

 290-7 

 290-8 



296-4 

 291-8 

 290-62 

 290-88 



Table XVII. gives the calculated values of the hypothetical 

 critical temperature as compared with the real critical tem- 

 perature. The former is found to be everywhere lower than 

 the latter (except for mixture 0*43 C0 2 -C 2 H 6 , where the 

 calculated value is 0°'08 above the observed T c , a difference 

 almost within the limits of experimental errors) : for the 

 maximum mixture the two naturally coincide. The differences 

 are very small, especially with N 2 0-C 2 H 6 and C0 2 -C 2 H 6 . 

 For C 2 H 2 -C 2 H 6 they are somewhat higher for mixtures 

 containing more C 2 H 6 : this is in agreement with the fact 

 that the critical phenomena were more marked for those 

 mixtures than for the others. In plotting the values of 

 Table XVII. against the x's, two curves are obtained, connecting 

 the same points C : and C 2 and touching at a point corresponding 

 to B. The curves are close together and the minimum of a/b 

 should belong to approximately the same value of x as the 

 minimum T c . The existence of a minimum for a/b depends on 

 a 12 /b 12 being smaller than both ajbi and a 2 /b 2 *. Table XVIII. 

 gives the values of x for the minimum of a/b and for the 



* Van der Waals, Arch. N6erl. xxiv. p. 23. 



