Relationship between Molecular Cohesion 487 



appear to exert no effect. By this method, as by the cohesional, 

 all organic chlorine compounds examined were found to have 

 trivalent chlorine and fluorine was monovalent. The agree- 

 ment was good in regard to other elements also. 



The connection between cohesion and diamagnetism is, 

 therefore, again an indirect one. Both involve the molecular 

 weight and the number of valences, but it is clear that cohesion 

 is independent of molecular form, or very largely so; whereas 

 whether a substance is magnetic, or diamagnetic, may depend, 

 in part upon this very factor. Oxygen in an elemental form, 

 is paramagnetic, not diamagnetic, and is quite anomalous in 

 Pascal's scheme; whereas the cohesion of oxygen is not anomal- 

 ous. In other words, whether a body is, as a whole, para- 

 magnetic or diamagnetic, and to what degree, depends, prob- 

 ably, on the possibility of the orientation of the molecules, 

 their polarity, etc., factors which do not seem to affect their 

 cohesion or gravitation. Nevertheless cohesion and magnetic 

 properties are, no doubt, closely related, since both depend 

 on the same molecular properties, only magnetism involves 

 still other properties, (form) not involved in cohesion. 



The fact that cohesion is thus determined by the number 

 of electron couples (atomic and valence) in the molecule 

 plainly points toward the conclusion that cohesion is either 

 electro-static or electro-magnetic in nature. Both of these 

 possibilities have already been suggested. Sutherland, * from 

 his discovery of the relation of cohesion to valence in salts, 

 inferred at first that the cohesion must be of an electromagnetic 

 nature. He supposed these rotating electron couples acted 

 like little magnets, and he attempted to show, though whether 

 successfully, or not, I am unable to judge, that small magnets, 

 at sufficient distances apart, would attract inversely as the 

 fourth power of the distance between them, and this he sup- 

 posed to be the law of molecular attraction. This conclusion 

 was attacked by van der Waals, Jr., 2 who concluded, also 



1 Sutherland: Phil. Mag., [6] 19, i (1910); 4, 625 (1902). 



2 Van der Waals, Jr. : Kon. Akad. v. Wetensch. te Amsterdam, Pro- 

 ceedings, n, 132 (1908-1909). 



