356 Intelligence and Miscellaneous Articles. 



results and mine is pointed out and discussed. The results are 

 not antagonistic if put into their proper place with respect to 

 one another. As the subject is one of great importance and it is 

 necessary that some fundamental ideas about it should once for all 

 be settled, I beg to be permitted to emphasize a few of the points 

 contained in the papers mentioned. 



In investigations of the nature of the law of attraction between 

 molecules giving rise to the internal heat of evaporation and 

 surface tension, it is obvious that the investigation should be 

 mathematically sound. Thus it is not only necessary that the 

 formulae deduced from the law assumed should agree with the 

 facts, but it must also be shown that no other law can exist. Now 

 I have shown that the law deduced must contain an arbitrary 

 function (Phil. Mag. Jan. 1911, p. 83). This result is based on 

 no assumptions whatever, but is a mathematical consequence of 

 the nature of the heat of evaporation and surface tension. It 

 follows therefore that we can obtain an infinite number of laws of 

 attraction each of which gives rise to formulae agreeing with the 

 facts, which correspond to different forms of the arbitrary 

 function, but we cannot be sure that any one of the laws is the 

 true one without further evidence. Thus the inverse square law 

 of Mr. Mills is obtained by giving the arbitrary function a certain 

 form, which also determines the constant in his formula for the 

 heat of evaporation, giving a good agreement with the facts. But 

 it can be easily shown that the law cannot be true, for if it were 

 the attraction is that of gravitation and it can be shown that this 

 cannot account for the magnitude of the heat of evaporation (loco 

 cit. p. 89). In the paper Mr. Mills refers to the arbitrary 

 function was put equal to a coustant to see what agreement with 

 some of the facts is obtained on this supposition, but it was not 

 pointed out in that paper that it is arbitrary. 



Mr. A. Batschinski in a letter published in the Phil. Mag. of July 



points out that the formula — ¥ — — .,= constant, where L denotes 



„ .ft -P. 



the internal heat of evaporation, appeared in a paper of his pub- 

 lished previously to one of my papers in which it was given. I am 

 sorry I missed seeing it. But I would like to point out that I 

 did not obtain the formula empirically as he did, but by giving the 

 arbitrary function in the law of attraction discussed above a 

 certain form, which determines the nature of the above constant, 

 and therein lies its principal interest (Phil. Mag. Oct. 1910, p. 678, 

 and Jan. 1911, pp. 98-99). T ours faithfully, 



E. D. Kleeman. 



