910 Dr. R. D. Kleeman on the Attraction Constant of a 



p Now at corresponding temperatures H is the same for all 

 liquids, and P is constant for a compound and its substitution 



v 

 products. The quantity ^ 7 — 8/4 will therefore be constant 



tor a compound and its substitution products at corres- 

 ponding temperatures. The ninth column of Table II. bears 

 this out for the critical molecular volumes of a set of 

 substances. 



By means of equations (2) and (b) we obtain 



P 3/ V x p^v 



* = -Hi-(2Vm 1 ) 1 ' a or / h sV2=-W ' ( 3 > 



(2^0 l/s 



Thus - 



•£ / — xi^ is constant for a compound and its substi- 

 tution products at corresponding temperatures. 



Since — = constant for corresponding states, where E 

 denotes the potential energy of the surface film of a liquid, 



we have that ~z< / — .172 is constant under the same 

 conditions. (*V»h) 



From equations (c) and (2) we have 



T B"-Y2Vm l L, _B 2 P 



where L??i = L! and is the molecular internal heat of evapora- 

 tion of a liquid. The quantity — , — is thus constant under 



the same conditions as the above quantities. This is shown 

 by the last column of Table II. The internal latent heats 

 used relate to 2/3 of the critical temperature ; they have 

 been calculated from the tables of latent heat given by 

 Mills *. 



From equations (c) and (2) we have 



_M 2 P'/ 4 ,— 1/4 P _M 2 P 7 / 4 , K . 



P-- 5 Yj2-(^Vm 1 )^ or (S ^~y/4 ^f]2~ • - (5) 



P 

 Thus ,_-, / — N f74 is constant under the same conditions as 



the quantities discussed above. This is borne out by the 



tenth column of Table II., using the critical pressures of the 



substances. Since the exponent in (2\An 1 ) 1/4 is \ the value 



* Journ. of Phys. Cheni. vol. viii. p. 405 (1904). 



