407 



i.e. wliether (in approximation) I'^fp is <^ or >1 — Vj -^i (1— '^)- 

 And, of course, nothing can be said beforehand with regard lo this. 



9. Some numerical results. 



That in case of mixing of normal substances the lieat of mixing 

 is actually =0 or very slight (+ or — ), when the critical pressures 

 are about equal, appears among others from the following examples 

 (compare also Table V on p. 64 — 65 in Kkemann's book). 



CeHjCl — CeHsBr {p^ = 44,6 and 44,6) 



Dimethylaniline— m. Xylene („ > 35,8 > 35,8) 



Amylformiate — Propylacetate (» » 34,1 > 34,8) 



p-Xylene — m-Xylene ( > * 35,0 » 35,8) 



p-Xylene — o- Xylene (» > 35,0 » 36,9) 



m-Xylene - o-Xylene (» > 35,8 » 36,9) 



ï£;=0to3,3(YouNGl903andKR.) 



-L 2 8 1 



2 I 



^' Kremann c.s. 



~ ^'^ 1914. 



+ 2,3 



+ 2,0 1 



Of the many mixtures studied, of which the critical pressures 

 are more or less different, we liave calculated ^) the following ones 

 according to (10") for a comparison with tlie results of the obser- 

 vation. 



1. Toluene-Benzene. Here we have 



For the calculation of -^^ = v/ : V, (v/-f y/) we may either take 

 the densities at the temperature of the experiment, or — as v^" and 

 y/ will be proportional to bjc^sindbjc.^ — introduce the above values 

 of 6bk {S is a certain numerical value). We have done the latter. 

 We now find : 

 ?<;=^/,X 1,1X562 (0,00462 + 7,1, 03. 0,068 1 0,120-^^1,1. 0,068. 1,744;) 



r= 2162 (0,00462 + 0,0117 j0,120 - 0,033;) 

 = 2162 (0,00462 + 0,00102) = 2162 X0,00564 =: 12,2 gr.cal. 

 Alexejew found 14,0 (from Young follows 15,8, and Kr. found 

 18,9). 



^) Both in Table 5 for w (on p. 164) and in Table 23 for Ai? (p. 175) the 

 "calculated" values in Kremann's book are all inaccurate, because instead of 

 the accurate formula derived by me for Av, an approximate one was used Besides 

 27/9 BTc was put in w instead of a/„ = "/& = IRTc , which in itself already 

 causes the values calculated for w to be twice too small. Etc. 



