4SS 



Here y = 0,711, /9/. = 0,406, /?, =::/?« X 1^439 = 0,411 ; 0,19 

 again remains considerably below this. 



Com bin in, iü; llie found values of fi,, in a (able and comparing them 

 with the theoretical values, we get the following survey. 



tn 



1.95 1.43 1.13 1.04 1.01 



0.95 0.89 0.82 



R calc. 



0.49 0.46 0.435 0.43 0.43 



/? found I 0.55 0.51 0.45 0.43 0.42 



0.42 0.42 0.41 

 0.37? 0.28? 0.19? 



As was alread}' remarked above, the great deviation, especially 

 below Tk {m <C 1)? must not be ascribed to the theory, but to the 

 ex])eriment, or to association in the vapour. 



For the found values of l^g become, as we shall see, even negative, 

 hence impossible, at still lower temperatures — while also /?,,,„^,. is 

 continually found smaller than /?//y. , which of course points to 

 something particular in the vapour: either association, or inaccurate 

 vapour- or volume determinations, in consequence of a systematic 

 erroi'. (Consult also (j. of § 18 for a possible explanation.) 



18. The region of coe.vistence. (Cf. Comm. 131 and These Proc. 

 of Nov. 1913 (Comm. 138)). 



For the calculation of P from the given values of the coexisting 

 vapour and liquid densities it is to be regretted that the vapour 

 pressure observatio-ns (see also Comm. 115) have not been made at 

 exactly the same temperatures as tlie density observations. This has 

 rendered interpolations necessary, which of course impairs the 

 perfect accuracy of the e, which will make its influence felt chiefly 

 on the /^-values which are calculated from the vapour densities. 



In this connection we should not omit mentioning that the value 

 of ƒ, calculated from the first observations ,of the vapour tensions 

 (Comm-. 115). is much too low, viz. 5,712, whereas the much better 



30 



Proceedings Royal Acad. Amsterdam, Vol. XVII. 



