MODELS OF POSITIVE ION 329 



the tube is increased as the moment of momen- 

 tum of the tube is increased, and therefore the 

 pull between the atom and the corpuscle is also 

 increased. Hence an atom with this great amount 

 of internal rotational energy will be attracted 

 towards a negatively electrified body, and behave, 

 as it were, as a positive ion. If the corpuscle 

 approaches very closely to the atom, it will disturb 

 the motion of the electron and tend to slow down 

 its motion. 



The molecule, therefore, when it does not carry 

 a free charge will merely radiate extremely pene- 

 trating waves of very high frequency. These, in 

 fact, are the properties of the emanation. 



As we have seen, the positive oxygen atom is 

 one of the chief factors in the phenomena of 

 phosphorescence. And the fact is also another 

 instance of stored-up energy, except that here the 

 corpuscle approaches much more closely to the 

 rotating system of electrons in the atom. 



The apparent paradox that the radiation is due, 

 as the Zeeman efi"ect requires, to motion of a 

 negative charge on the electron, but that it is 

 from the positive ion that radiation comes, is a 

 point of no small importance in the theory of 

 luminosity. 



The argument for the existence of aggregates 

 of molecules has thus been pursued and subjected 

 to the test of experiment. Notable amongst these 

 is the change of absorption in the fluorescent light 

 during fluorescence. This phenomenon, which has 



