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BELL SYSTEM TECHNICAL JOURNAL 



mass of the O'^ isotope are much more nearly integers than many of 

 the chemical atomic weights, but they are not exactly integers. The 

 most famous of all the chemical misfits — the ratio 1.008 to 16.000 of 

 the combining weights of hydrogen and oxygen — is almost exactly 



I 45 

 < 



10 15 20 25 30 35 40 45 50 55 60 65 



Z 



Fig. 6 — Diagram of the isotopes of the elements of atomic numbers up to 60, the 

 difference between mass-number A and atomic number Z being plotted against Z. 



repeated between the isotopes; for both these elements are of the class 

 in which one kind of atom predominates immensely over the rest. 

 The ratio of the masses of the principal isotopes, H^ and O'*', is one of 

 those on which the highest resources of the technique of mass- 



