286 



Proceedings of the Royal Irish Academy. 



"wMch represents Kepler's well-known third law that the squares 

 of the periodic times are proportional to the cubes of the distances. 



Let us now take a molecule of chlorine, and represent it as^ 

 follows : 



If now. 



then, 



liy - attraction coefOLcient of CI CI, 

 I = radius of chlorine molecule orbit, 

 coi = angular velocity of chlorine molecule orbit, 

 /3 - mass of chlorine ; 



fx,(3 = 4P<o,\ (2) 



