Constitution and Stability of Atom Nuclei. 337 



the alpha particle, especially after it is combined in a com- 

 plex nucleus, to give Rutherford's p^e particle and one 

 neutron (pe). However, Rutherford's work at present 

 seems to indicate that the free alpha particle remains stable. 



Fig. 8. 

 p. 2 9 p a e 



( 



) 



( 



), 



Pi e l 



A A 



o V 



2(iV) 



The writer was the first to show that the fact that the alpha 

 particle exhibits the same packing effect as the other com- 

 plex nuclei, indicates that it is extremely more stable with 

 reference to disintegration into electrons and protons, than 

 the more complex nuclei with reference to disintegration 

 into alpha particles This does not mean that the alpha 

 particles when joined in complex nuclei cannot be broken 

 apart in some other way than into the primary protons and 

 electrons. It seems that this latter type of complete disin- 

 tegration involves the expenditure of more energy than that 

 which the projected alpha particle possesses in the kinetic 

 form, but it is not certain that the neutron and the p z e 

 particle would differ very much from an alpha particle in 

 the magnitude of the packing effect, particularly since it 

 seems to be only the p s e particle which escapes from the 

 nucleus. 



One of the most important problems concerning nuclear 

 structure is that of demonstrating experimentally a variation 

 in the packing effect in various complex nuclei, provided it 

 is great enough to be so demonstrated. One of the most 

 hopeful atomic species for experimental work is the lithium 

 of atomic weight 7, since that is the atomic species which, 

 provided its nucleus contains one alpha particle, contains ;it 

 the same time a very large percentage of material (3/ 7 o£ 

 the total mass) which cannot be a part of an alpha particle. 



Phil. Mag. Ser. G. Vol. 42. No. 249. Sept. 192] . 2 A 



