Constitution of Atoms. 285 



The suggested Dotation * does not indicate any reason why 

 nitrogen atoms should emit both b z e and b ions under a-ray 

 bombardment, while oxygen atoms emit b%e but no b ions. 

 Sir E. Rutherford seems inclined to infer that barons 

 exist, as such, in the nitrogen- nucleus and not in that of 

 oxygen, just as it has been usual to take the emission of 

 a-rays as evidence that the radioactive atoms contain helium 

 nuclei as such. Of course it may be so, but the inference 

 may not be justiiied. A similar inference, long ago proved 

 incorrect, is embalmed in the term carbohydrate. The 

 sugar molecules do not contain water molecules as such, 

 though they do, under certain conditions, emit water mole- 

 cules and leave a residue of carbon. 



It need hardly be said that no claim is made that the 

 formulae suggested in this paper express the atomic consti- 

 tutions in the full sense of the term. There are really as 

 yet no data to justify such an attempt, so far at least as the 

 nuclear part of the atom is concerned. They do, however,, 

 express correctly the nuclear charge (N) and mass (2N + n) 

 and the shell charge, whether of atoms or of ions ; they 

 locate the difference between isotopes in the numerical value 

 of n (and there is no other difference) ; and they serve to 

 correlate the whole system of atoms and their proved pro- 

 cesses of disintegration by means of a comparatively simple 

 notation, which may be employed to illustrate either general 

 rules or special instances. 



If the chart of radioactive transformations, as given by 

 Soddy (J. C. S. Jan. 1919, p. 16) be re-drawn, making the 

 N scale horizontal and the A scale vertical and one unit of 

 the former equal in length to two units of the latter, the 

 n values of all the atoms can be read off on a scale drawn 

 diagonally from N.E. to S.W. across the centre of the chart. 

 A succession of a-ray changes is thus marked by arrows 

 running along a line of equal n, pointing from S.E. to N.W., 

 and such lines of equal n may pass through the symbols of 

 atoms belonging to the same or different series, just as do 

 the vertical isotopic lines or the horizontal isobaric lines. 



The University of Melbourne, 

 8th October, 1920. 



* It may be pointed out here that the {b.x) particle, isotopic with the 

 He nucleus, may be formulated as [Aoe) 2 (^e)_ 1 ], just as the baron may 

 be writen l(b 2 e)(be)_ 1 ~\. These formulae are, of course, merely a repeti- 

 tion of the equations already given for intranuclear changes by which 

 the particles are generated; but the negative value ot* n serves to 

 classify them together and apart from other ions. II is no longer quite 

 unique in this respect. 



