98 Dr. R. D. Kleeman : Determinations of the Law of 



forms. This furnishes the means for further tests of the 

 truth of the above law. 



We have seen that Mills, assuming that the attraction 

 between two molecules separated by a distance z is given 



by — ^j where K 2 is a constant, obtained the formula 



L = D(p\' 3 — p}J 3 ) for the latent heat, which was found to 

 agree well with the facts. To reduce the general law of 

 attraction to this form we must put 





m 



where p c is the critical density and S is a numerical constant. 



Qt 



The value of the constant K 2 is thus -*- (2 a/™,) 2 , and the 



value of D therefore — fe(2\/ wl i) 2 . These values of D 

 m 1 * 6 ' 



should agree with those obtained by Mills from latent heat 



data. This is tested in Table III. for a number of liquids, 



Table III. 



Name of liquid. 

 Ether 



L 



12,830 Pc (S\/m 1 ) 2 



Name of liquid. 



L 



12,830^(2 s/m,)* 



P y*- P ys 



109-5 

 103-6 

 85-6 

 81-2 

 561 

 44-4 

 44-1 

 26 





m^ 



m 7 / 3 



104-4 



98-1 



863 



105-4 



109-9 



102-8 



98-7 



93-0 



112-7 



77-57 

 100-3 

 119-3 

 118-4 



98-7 



85-31 



90-24 



1 



Benzene 



1076 



Di isopropyl 



Di isobutyl 



Isopentane 



Hexametbylene 



1369 



Fluorbenzene 



97-5 



Cblorobenzene 



77-3 



Normal pentane . 

 „ bexane... 

 „ heptane . 

 ,, octane ... 





56-4 



Iodobenzene 



Carbon tetrachloride . 

 Stannic chloride 



41-8 

 52-8 

 26-4 



which contains the mean values of —r^ ^ obtained by 



pl /3 -pl /3 J 



Mills, and the corresponding values of ——(Xx/m^ 2 , putting 



S = 12,830. The agreement is fairly good. 



If we assume that the law of attraction between two 



molecules is — j--, we have that Kj must be equal to 





