Constitution -and Stability of Atom Nuclei. 313 



elements alone make up 95*91 per cent. o£ the entire 

 number of atoms in the meteorites. It may be noted here 

 that all of the unknown elements but one have odd atomic 

 numbers. 



The work o£ Aston shows that silicon consists of isotopes 

 of atomic weights 28,29, and possibly 30, while Dempster 

 has found that magnesium consists of 75 per cent. Mg 24 , 

 12'5 per cent. Mg 25 , and 12*5 per cent. Mg 26 . The writer 

 has presented evidence which indicates that iron, the major 

 isotope of which has the atomic weight 56, contains a small 

 percentage of one or more other isotopes of lower atomic 

 weight, with a probable atomic weight of 52 for the lightest 

 isotope. 



Table I. (as presented below) gives the atomic percentage 

 of the most abundant isotope of each of these five elements, 

 these being the five most abundant atomic species in the 

 meteorites. 



Table I. 



The Atomic Percentage oe the Five Most Abundant Atomic 

 Species in the Meteorites (10 Iron and 350 Stone). 



Atomic Atomic IST — P 



species. percent. (- M). P. N. N/P. 



O 53-16 8 16 8 0-5 



Mg 24 9-86 12 24 12 0-5 



Si 28 1382 14 28 14 0'5 



S 1-46 16 32 16 0-5 



Fe 56 1228 26 56 30 0-536 



Total 90-58 



This table shows the important relation that in all of the 

 most abundant species of nuclei the number of positive 

 electrons (P) is even, the number of negative electrons (N) is 

 even, so the net nuclear charge (M) is also even. In 

 addition to this it is to be seen that for all of the lower 

 atomic numbers N = P = M, and N/P = J. 



Importance of the Ratio (N/P) of Negative to Positive 

 Electrons in Atom Nuclei to Nuclear Stability. 



Table I., given above, indicates the surprising fact that 

 five out of the hundreds (probably 300 or more) o( atom if 

 species which exist, make up more than 90 per cent, of all 

 of the atoms in the meteorites. It illustrates also the 

 important law that among the light atoms of atomic 



