THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 





[SIXTH SERIES.] 



DECEMBER 1902. 



LXX. The Electric Origin of Molecular Attraction. 

 By William Sutherland *. 



Introduction. 



BY molecular attraction we understand intermolecular 

 forces whose effects are not appreciable at distances of 

 a larger order than molecular, thus excluding ordinary gravi- 

 tation and ordinary electric and magnetic force. But the 

 law of molecular attraction which I have discussed (Phil. 

 Mag. [5] xxxv., xxxix., and other volumes), namely, that of 

 the inverse fourth power, can be most readily accounted for by 

 tracing it to the electric polarity which the electron theory of 

 chemical valency necessarily ascribes to molecules, because 

 the theory of magnetism familiarizes us with an inverse 

 fourth power force between magnets at distances great com- 

 pared with their lengths. In applying this known magnetic 

 result to account for molecular attraction we are at the outset 

 confronted with the difficulty that in the case of magnets the 

 force is as often repulsive as attractive, the nature of the 

 force depending on the relative direction of polarities in the 

 magnets, whereas the molecular forces required to account 

 for cohesion must be preponderating!}" attractive. 



"We have to investigate how, if the electric axes of molecules 

 are distributed at random, and repulsive forces would there- 

 fore seem to be as common as attractive, it is possible for the 

 attractive so to prevail over the repulsive as to leave a final 

 balance of attraction, as if on the average all the forces were 

 * Communicated by the Author. 



Phil Map. S. 6. Vol. 4. No. 24. Dec. 1902. 2 T 



