338 On the Constitution and Stahility of Atom Nuclei. 



The constancy of the packing effect in most atomic species 

 suggests that it may be due to a property of the electrons 

 themselves. However, if the packing effect in the group 

 ])- d e 2 is materially different from that in the alpha particle 

 p±e 2 , the fact may be capable of demonstration in a reasonable 

 time, most easily by determining whether the percentages 

 of the isotopes of atomic weight 6 and 7, as determined by 

 the positive ray method., give the mean chemical atomic 

 weight as determined with very great care. The writer 

 wishes to thank Professor A. C. Lunn, of the department of 

 Mathematics, for suggestions concerning the isotopic number 

 plots. 



Summary. 



1. The paper presents seven experimental correlations 



which are believed to exhibit the fundamental relations 

 between the stahility and composition of atom nuclei. 

 These are summarized near the beginning of the 

 paper, and need not be repeated here. Nuclear 

 electrons seem to be associated in pairs, and alpha 

 particles in groups of 10 or usually less, but sometimes 

 more. 



2. Three methods of classifying isotopes are presented. 



While all of these were suggested in a somewhat 

 different form in an earlier paper by the writer, they 

 were not outlined with sufficient definiteness to show 

 their naturalness, and their relation to nuclear 

 stability. The three methods are (1) Classification 

 into four classes according to the cddness or evenness 

 of the number of electrons and protons in the 

 nucleus; (2) Classification into isotopic numbers 

 which vary from —1 for hydrogen and Rutherford's 

 lower isotope of helium, to for the most abundant 

 atomic species, up to 54 for uranium 238 ; (3) Classi- 

 fication according to series relationships. 



3. The problem of nuclear stability is discussed in detail, 



and the relations to the above systems of classification 

 are pointed out. 



4. The discussions and the graphical plots show a marked 



periodicity in the variation of abundance, atomic 

 stability, and a number of functions which express the 

 composition of atom nuclei. This is the only set of 

 periodic relations ever discovered in relation to atoms 

 or elements, which is entirely distinct from the 

 periodic relations found by Newlands and MendelejefF. 



