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442 Prof. W. L. Bragg and Messrs. James and Bosanquet : 



The comparison between the two analyses (dotted curves) 

 and the atom model we started with (continuous curve) is 

 shown in fig. 2. The abscissas represent the radii of the 

 shells in A, the ordinates the total number of electrons 

 inside a shell of that radius. When the limits of the atomic 

 structure are reached, the curve becomes horizontal at the 

 value 10, corresponding to the ten electrons. The analyses 

 not only indicate with considerable accuracy the way in 



n3 

 fl 4 



Fig. 2. 



xr._ 



1-5 



sphere, measured 



2-0 

 Angstrom units. 



2-3 



which the electron-content grows as we pass to spheres of 

 larger radii, but also tell definitely the outer boundary 

 of the atomic structure. Both give a number of electrons 

 very nearly equal to zero in the shells outside O70 A. 



5. The F curves for sodium and chlorine can be solved 

 in the same manner. We have expressed our results in 

 two ways. 



First, we have supposed the electrons to be grouped on 

 shells. The numbers of electrons on each shell, and the 

 radii of the shells, have been so adjusted as to give the best 

 possible fit to the experimental curves. In the case of 

 sodium it is found that a fit can be obtained with two 

 shells, and in the case of chlorine with three shells. The 



