ON ELECTROLYSIS. 743. 
circumstances happen to be loosed or joined, per molecule of that sub- 
stance, be it element or be it compound. 
Evidence for the truth of this law has been accumulated by Daniell 
and Miller, by Wiedemann, Hittorf, Matteucci, Becquerel, Soret, and 
Buff. They all separate the anode from the cathode vessel by various 
devices, and it appears as if the more carefully secondary actions are 
prevented or allowed for, the more nearly is the law true. It may be 
sufficient to refer to Wiedemann’s ‘ Hlektricitit’ for an account of a mass 
of research. 
Further evidence may be suggested as given by the behaviour of 
certain electrolytes in series-contact, without electrodes intervening, after 
the manner of Davy; for, if two meeting ions were not precisely equiva- 
lent, the one in excess would have to appear in a solitary state. Sucha 
phenomenon might be well looked for, but it has never yet been certainly 
observed. 
The physical import of law 2 is that it extends the statement of law 1, 
about each atom in a single substance having the same definite electric 
charge, to all electrolytes, and enables us to conclude that .a definite 
quantity of electricity belongs to each unit of affinity of every atom of 
whatever kind; in other words, that every monad atom or radicle (while 
being liberated on an electrode, at any rate) has associated with it a certain 
definite quantity of electricity, no matter from what compound it is being 
liberated, and no matter what the name of the radicle itself may be ; that 
every dyad radicle has twice this quantity associated with it, every triad 
three times as much, and so on. 
It is impossible to overlook the immense interest of such statements 
as these to any chemist wishing to grasp the real meaning of chemical 
combination and affinity. But the tremendous import of the law to phy- 
sicists also may be more vividly indicated by pointing out that the 
electric charge of a nascent monad atom is a kind of natural unit of 
electric quantity, and that fractional portions of such units are, in elec- 
trolysis at least, wnknown. One may have integral multiples of this 
natural unit, as in dyads and triads, but one cannot have submultiples, 
until chemists discover some quantivalence less than that of hydrogen, 
or rather until they see reason to abandon the idea that quantivalence 
proceeds by integers (the basis of their ‘atomic theory ”) altogether. 
Maxwell no doubt intends to call attention to the superlative interest 
of the fact that there appears to be a non-divisible electrical unit, when 
he calls it ‘a molecule (his customary cautious name, intended to include 
atoms also if they exist) of electricity.’ And Helmholtz does not shrink 
from staring the possibility in the face that electricity may turn out to. 
be as ‘atomic’ as matter. 
Atomic Idea of Electricity ; Electrostatic Theory of Chemistry. 
Let us first consider what is really the evidence for sucha view. Elec- 
tricity is found to associate itself with the atoms of matter in multiples of 
one fundamental quantity, but never in fractions of it; it does not then 
follow that fractions of this quantity are impossible, but it may well be 
that we have never yet dealt with them. The evidence for the atomic 
nature of electricity is pretty much of the same nature as that for the 
_ atomic nature of matter. Gains and losses of electricity are apparently 
continuous, but so they are of matter; all that is necessary to satisfy 
