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LXXXIII The Coalescence of Liquid Spheres — Molecular 

 Diameters. By Wilson Taylor, Physics Laboratory, 

 University of Toronto, Canada*. 



MOLECULAR phenomena are commonly considered as 

 being caused by some kind of attraction which mole- 

 cules have for each other when they are near together. This 

 idea has been the basis for the explanation of such phenomena 

 as the .liquefaction of gases where the molecules near to each 

 other are attracted so powerfully that they remain per- 

 manently in an aggregation. The idea was probably first 

 suggested by Newton, and Laplace pointed out that the 

 phenomena of surface-tension would result from the necessity 

 for this attraction being unequally distributed among the 

 molecules near the surface of the liquid. But he had to 

 assume that this attraction ceased to be effective when the 

 distance between the molecules was beyond a certain range. 

 This has also been made the basis for the explanation of 

 adhesion and solidification. Maxwell carried out Laplace's 

 idea further, using it as a mathematical basis for the pro- 

 perties of the film in a soap-bubble. But he found difficulty 

 in accounting for the formation of the black spots and the 

 sudden changes in the tension of liquid films noticed by 

 Riiker and Reinold in 1886. In recent years, however, the 

 constitution of the soap and other films has been studied in 

 great detail, and there has been expressed by various investi- 

 gators some doubt as to the validity of the explanations 

 which are based on the attraction of molecules as masses. 

 From direct observation the soap-bubble appears to be 

 composed of a number of strata whose multiples differ in 

 thickness by steps which have been estimated to be from 

 1 to 10 fxfju in height. The difficulty of explaining this by 

 the attraction of molecules, or by any other hypothesis, has 

 been so great that Perrin, who has made an exhaustive study 

 of the bubble (Annales de Physique, Sept. 1918), speaks of 

 it as an enigma. 



This difficulty led the writer to study the action of two 

 spheres of the same liquid when near to each other and when 

 they came into contact; and the following may be considered 

 as an attempt to consider an alternative basis for the explana- 

 tion of molecular phenomena. 



He was not able to find any direct evidence that such 

 spheres attracted each other, no matter how small they were 



* Communicated by the Author. 

 Phil. May. S. 6. Vol. 41. No, 246. June 1921. 3 M 



