Mr Campbell, The number of Electrons in an Atom. 291 
explosion might leave each of the remaining electrons with the 
same energy as it possessed before the disintegration: the energy 
of the system would merely decrease in the same ratio as the 
number of the electrons in it. 
Accordingly we may conclude that if our hypothetical structure 
of the atom — electrons moving in a sphere of positive electricity — 
is at all near the truth, the number of electrons in a radium atom 
must be greater, and probably very much greater, than 1200. 
It is possible, indeed probable, that this structure of the atom 
is not at all near the truth : that greater complexity will have to 
be attributed to the positive portion of the atom and that some of 
the energy of radioactivity may be derived from a change in the 
constitution of this part of the atom. But even if a fundamental 
reconstruction of our notions of the atom should be found 
necessary, the considerations that have been advanced may be of 
some service in drawing attention to features that must be taken 
into account by all designers of model atoms. 
