662 SCIENCE PROGRESS 



of the helium ion with two electrons, as the most stable and 

 readily formed of all compounds of helium. The intense affinity 

 of helium, " an affinity far beyond anything we have experience 

 of in the case of any other element," is, on this view, exerted not 

 between hypothetical smaller material atoms within the helium 

 molecule, as Prof. Armstrong originally proposed, but between 

 the elementary material particle as a whole and its electrons. 

 This affinity is so intense that the compound has never been 

 decomposed by chemical agencies, and, in consequence, other 

 compounds than the monatomic complex containing two electrons 

 have never been obtained. 





