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V. The Relation of Temperature and Molecular Attraction. 

 By J. E.Mills*. . 



Part I. — The Law of Molecular Attraction. 



IN a series of papers t in the Philosophical Magazine 

 Dr. R. D. Kleeman has investigated a possible fifth 

 power law of the molecular attraction, and in this investi- 

 gation he has used data taken from a paper by the author. 

 Dr. Kleeman seems entirely to have overlooked the fact that 

 the data were used by the author to prove the truth of au 

 equation of the form 



T "p 



3 j — 3-^ = constant, or \ = /u/ ( y/d — v'D). . (1) 



Here L is the heat of vaporization of one gram of the 

 liquid, E e is the energy spent in overcoming the external 

 pressure as the liquid expands to the volume of the saturated 

 vapour. L— E e is therefore the so-called internal heat of 

 vaporization, and is called \. d and D are the densities of 

 the liquid and saturated vapour respectively at the tempe- 

 rature of the vaporization. The constant given by the 

 equation is called fjJ. 



This relation was theoretically derived on the supposition 

 that the molecular attraction varied inversely as the square 

 of the distance apart of the molecules, that it did not vary 

 with the temperature, and that the total force proceeding 

 from a molecule was a constant for any particular molecule. 

 The equation has been extensively studied and discussed by 

 the author J, and it is certain that if the equation is true 

 many of the conclusions of Kleeman are erroneous. 



There is no doubt whatever that the equation is true. The 

 fact that the proof has been so completely overlooked by 

 Kleeman is a sufficient reason for republishing here a very 

 brief summary of the results obtained for comparison with 

 his results. I give such a summary in Table I. below. A 

 mean value of the constant rather arbitrarily chosen for each 



* Communicated by the Author. 



t Phil. Mag. xix. p. 795 (1910), and later articles. 



I Journ. Phys. Chem. vi. p. 209 (1902) j viii. p. 383 (1904) ; viii. p. 593 

 (1904) ; ix. p. 402 (1905) ; x. p. 1 (1906) ; xi. p. 132 (1907) ; xi. p. 594 

 (1907) ; xiii. p. 512 (.1909); Journ. Amer. Chem. Soc. xxxi. p. 1099 (1909); 

 Phil. Mag. Oct. 1910 ; Journ. Phys. Chem. May 1911. These papers need 

 revision badly. The eighth paper should be read first, then the last two 

 papers mentioned. The remaining papers can then be briefly examined 

 in the order in which they were written, making allowance for some 

 necessary changes. See also Mills and MacRae, Journ. Amer. Chem. Soc. 

 xxxii. p. 1162 (1910). 



