Structure of the Atom. 261 
puseles would escape from it, while the positive charge on 
the system due to the escape of the 59th corpuscle would 
attract the surrounding corpuscles. Thus this arrangement 
could not remain permanently charged ; for as soon as one 
corpuscle had escaped it would be replaced by another. An 
atom constituted in this way would be neither electropositive 
nor electronegative, but one incapable of receiving permanently 
a charge of electricity. 
The group containing 60 corpuscles would be the most 
electropositive of the series ; but this could only lose one 
corpuscle; 7. e. acquire a charge of one unit of positive 
electricity; for if it lost two we should have 58 corpuscles— 
as when the group of 59 had lost one corpuscle—and in this 
case the system would be even more likely than the other to 
attract external corpuscles, for it would have a charge of two 
units of positive electricity instead of one. Thus the system 
containing 60 corpuscles would get charged with one, but 
only one, “unit of positive electricity : it would therefore act 
like the atom of a monovalent electropositive element. 
The group containing 61 corpuscies would not part with 
its corpuscles so readily as the group of 60, but on the other 
hand it could afford to lose two, as it is not until it has lost 
three that its corpuscles are reduced to 58, when, as we have 
seen, 1t begins to acquire fresh corpuscles. Thus this system 
might get charged with two units of positive electricity, and 
would act like the atom of a divalent electropositive element. 
Similarly the group of 62, though less liable even than 
the 61 to lose its corpuscles, could, on the other hand, lose 3 
without beginning to recover its corpuscles; it could thus 
acquire a charge of 3 units of positive electricity, and would 
act like the atom of a trivalent electropositive element. 
Let us now go to the groups at the other end of the series 
and censider the properties of the last of the series, the group 
of 67 corpuscles. The outer ring would be very stable, but 
if the system acquired another corpuscle, the 68 corpuscles 
would arrange themselves with a ring of 21 corpuscles on the 
outside ; as 68 is the smallest number of corpuscles with an 
outer ring of 21, the ring is very nearly unstable and easily 
loses a corpuscle. ‘Thus the group of 67 corpuscles, as soon as 
it acquires a negative charge, would lose it again, and the 
system, like the group of 59, would be incapable of being 
permanently charged with electricity—it would act like the 
atom of an element of no valency. 
The group of 66 would be the most electronegative of the 
series, but this would only be able to retain a charge of one 
unit of negative electricity ; for if it acquired 2 units there 
