“Ss? 
Structure of the Atom. 263 
compound of the electropositive and electronegative atoms 
will be formed. 
Just as an uncharged conducting sphere will by electro- 
static induction attract a corpuscle in its neighbourhood, so 
a corpuscle outside an atom will be attracted, even though 
the atom has not become positively charged by losing a 
corpuscle. When the outside corpuscle is dragged into the 
atom there will be a diminution in the potential energy, 
the amount of this diminution depending on the number of 
corpuscles in the atom. If now we have an atom A such 
that loss of potential energy due to the fall into the atom of 
a corpuscle from outside is greater than the work required to 
drag a corpuscle from an atom B of a different kind, then an 
intimate mixture of A and B atoms will result in the A atoms 
dragging corpuscles from the B atoms, thus the A atoms will 
get negatively, the B atoms positively electrified, and the 
oppositely electrified atoms will combine, forming a com- 
pound such as A_B.; in such a case as this chemical 
combination might be expected whenever the atoms were 
brought into contact. Even when the loss of potential 
energy when a corpuscle falls into A is less than the work 
required to drag a corpuscle right away from B, the existence 
of a suitable physical environment may lead to chemical 
combination between A and B. For when a corpuscle 
is dragged out of and away from an atom a considerable 
portion of the work is spent on the corpuscle atter it has left 
the atom, while of the work gained when a corpuscle falls 
into an atom, the proportion done outside to that done inside 
the atom is smaller than the proportion for the corresponding 
quantities when the corpuscle is dragged out of an atom. 
Thus, though the work required to move a corpuscle from B 
to an infinite distance may be greater than that gained when 
a corpuscle moves from an infinite distance into A, yet the 
work gained when a corpuscle went from the surface of A 
into its interior might be greater than the work required to 
move a corpuscle from the interior to the surface of B. In 
this case anything which diminished the forees on the 
corpuscle when they got outside the atom, as, for example, 
the presence of a medium of great specific inductive capacity 
such as water, or contact with a metal such as platinum 
black, would greatly increase the chance of chemical com- 
bination. 
The Existence of Secondary Groups of Corpuscles 
within the Atom. 
The expression given on p. 238 for the radius of a ring of 
corpuscles shows that it depends on ve/b*, where ve is the 
