76 THE TRUE VALUE OF a OF VAN DER WAALS' 



if the cohesion -varied inversely as a higher power of the distance 

 than the fourth, or if the mass was greater than this, owing to the 

 faster movement of the electrons, then the cohesion would be greater 

 and the electrons would cohere. If the electron is moving so fast 

 that its mass is Yiooo that °f a hydrogen atom then the cohesion 

 at 1 X I0 -10 cms. distance, disregarding any centrifugal effect of 

 their revolution, would be 32.02 dynes; the repulsion would be 

 only 2:3.75 dynes. They would cohere. The interesting conclusion 

 appears, if our reasoning and assumptions are correct, that if two 

 electrons come sufficiently close together, they will cohere. It may 

 be in this way that the nuclei of the atoms are built up and the 

 valence electrons captured and held by the atoms; and we do not 

 have to assume any positive electricity in the nucleus to explain 

 how the negative electrons are held together. 



Thus we have passed from the cohesion of molecules to the 

 cohesion of atoms to make molecules, and to the cohesion of elec- 

 trons to make atoms. What then is the relation to that cohesion of 

 masses which extends throughout space, the attraction of gravitation? 



IX. RELATION OF GRAVITATION AND COHESION. 



The numerical relation of cohesion and gravitation is given in 

 the formula a = JV 2 (m 2 /c >< ValjMf*. This formula shows that 

 what is called cohesion is but the gravitational attraction intensi- 

 fied in the immediate neighborhood of the molecules by the action 

 of the valence electrons. I do not yet see the significance of the 

 exponent two-thirds. This would seem to imply the importance of 

 the density of the lines of force, which would suggest that these 

 lines of force are repelling each other. Leaving this point for the 

 future we can look at the matter the other way around and in- 

 stead of considering cohesion as intensified gravitation we can with 

 equal right consider gravitation to be simply the' cohesional attrac- 

 tion from which one element has been absorbed, namely the effect 

 produced by the valence electrons. For some reason this element 

 cannot reach farther than the next layer of molecules. Whether this 

 is because it is absorbed by the ether as van der Waals suggested, 

 or whether it is because it is absorbed by the first molecule it 

 encounters, I am not sure, but from the relation of cohesion to 

 magnetism we might assume perhaps as more probable the latter 

 possibility. For some reason then it seems that the effect produced 

 on the gravitational attraction by the valence electrons cannot pene- 

 trate other molecules and so it is shut off by them. The idea occurs 



