262 Prof. J. J. Thomson on the 
would be 68 corpuscles, an arrangement which, as we have 
seen, rapidly loses its corpuscles. This group of 66 would 
therefore act like the atom of a monovalent electronegative 
element. 
The group of 65 would be less liable than that of 66 to 
acquire negative corpuscles, but, on the other hand, it would 
under suitable circumstances be able to retain 2 cor puscles, 
and thus be charged with 2 units of negative electricity, and 
would act like the atom of a divalent electronegative element. 
Similarly, the group of 64 would act like the atom of a 
trivalent electronegative element, and so on. 
Thus, if we consider the series of arrangements of corpuscles 
having on the outside a ring containing a constant number 
of corpuscles, we have at the beginning and end systems 
which behave like the atoms of an element whose atoms are 
incapable of retaining a charge of either positive or negative 
electricity ; then (proceeding in the order of increasing 
number of corpuscles) we have first a system which behaves 
like the atom of a monovalent electropositive element, next 
one which behaves like the atom of a divalent electropositive 
element, while at the other end of the series we have a system 
which behaves like an atom with no valency, immediately 
preceding this, one which behaves like the atom of a mono- 
valent electronegative element, while this again is preceded 
by one behaving like the atom of a divalent electronegative 
element. 
This sequence of properties is very like that observed in 
the case of the atoms of the elements. 
Thus we have the series of elements : 
He “in” Be. Bo 46 ON: HOm ih aaaes 
Ne Na Me Al St P SCL Ang 
The first and last element in each of these series has no 
valency, the second is a monovalent electropositive element, 
the last but one is a monovalent electronegative element, the 
third is a divalent electropositive element, the last but two a 
divalent electronegative element, and so on. 
When atoms like the electronegative ones, in which the 
corpuscles are very stable, are mixed with atoms like the 
electropositive ones, in which the corpuscles are not nearly 
so firmly held, the forces to which the corpuscles are subject 
by the action of the atoms upon each other may result in the 
detachment of corpuscles from the electropositive atoms 
and their transference to the electronegative. The electro- 
negative atoms will thus get a charge of negative electricity, 
the electropositive atoms one of positive, the oppositely 
charged atoms will attract each other, and a chemical 
