530 Lord Kelvin: Plan of a Combination of Atoms 
within this atom. The void atom will now experience 
diminished repulsion from the other atom, and an attraction 
towards the electrion diminished by a greater difference. 
Hence repulsion will predominate, and if the system is left 
free, the two atoms will separate to an infinite distance, the 
electrion remaining always within one of the two. The 
whole work done by the excess of repulsion above attraction 
will be spent in the generation of etherial waves, and uniform 
motion through ether, of the void atom and of the other atom 
with the electrion settled at its centre. For brevity, and to 
keep as nearly as possible in harmony with the language 
of J. J. Thomson, Rutherford, and other writers on the 
dynamics of radioactivity, I shall call this action, by which 
two atoms are sent flying asunder with very great velocity, 
an explosion. 
§ 7. To find the work done in this particular kind of ex- 
plosion : first separate the two atoms, leaving the electrion 
in the middle between them. ‘The attraction of the electrion 
4e\ 16¢é? 
on each atom a2 JP will exactly balance the repulsion Le? 
on it by the other atom; and therefore no work is done. 
When the two atoms are at a very great distance, bring the 
electrion slightly nearer to one atom than to the other and 
leave all free. The electrion will be drawn towards the 
nearer atom and will ultimately settle at its centre. The 
work done in this action (Aep., Table * of § 20) will be 
Hence this is equal to the work done in the explosion of $ 6, 
because the initial and final configurations of atoms and 
electrion are the same in the two cases. We may make r as 
small as we please, and so make the energy of the explosion 
as great as we please. 
§ 8. Similar considerations show that if e and e are placed 
on the circumference of the circle in fig. 2 instead of slightly 
within it, the configuration is unstable and is liable to an 
explosion in which one of the electrions ¢ is shot off to an 
infinite distance, while the other settles at the centre of the 
atom. And just as in § 7, we find that the work done in this 
explosion is equal to the work required to extract the elec- 
trion from the centre of the atom and carry it off to an 
* In this table a denotes the radius of the atom instead of 7 as at 
present: and e is the quantity of vitreous electricity belonging to the 
atom instead of 4¢ as at present. Thus instead of e? we have 4e’. 
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