230 Observations and Experiments concermng 
combination. For at every effort towards separation. the 
attraction begins to act, which apparently would permanently 
unite them. a : 
Mr. Davy has no where expressly mentioned his opinion 
that electric energies may be produced in this manner. Yet 
that he has it in view, I think, is deducible from his illustra-- 
tions of the electricities evolved by separation after contact, 
and of the energies being often increased by heating ; all 
of which are apparent after separation only. 
The improbability of this opinion becomes apparent, 
when it is considered, that although bodies are rendered 
electrical by separation, yet there are no grounds for sup- 
posing electricity evolved by contact. On the contrary, it 
is certain that forced states cannot exist together for any 
considerable length of time, especially if the contiguous 
bodies be metallic: and accordingly such bodies, while 
the contact continues, display no powers. Even by the 
hypothesis, electricity is rendered sensible by scparation 
only. Now as it will readily be granted that a power can- 
not act before it is created, I would ask, What is the cause 
of the combination of solids, which are attended by a coin- 
plete change of properties, by a violent evolution of heat 
and light, and other marked effects; which solids, from 
their state of existence, are sufficiently protected by aggre- 
gation from efferts towards separation by any mechanical 
cause? 
Since bodies which possess an affinity cannot exist in 
independently electric states, and since electricity evolved 
by separation is shown to be a cause insufficient for com- 
bination, I see no foundation for Mr. Davy’s first assump- 
tion,—that heterogenous particles of matterare in differently 
electrical states; but consider it as irreconcileable to the 
established laws of electricity and to reason. 
The second assumption,—that different particles of matter 
in combining must still be supposed to retain their peculiar 
states of evergy,—comes next under consideration. 
I begin by stating the principal evidence in favour of this 
supposition. When a compound is decomposed by Voltaic 
electricity, each component is invariably attracted to a de- 
terminate pole. The question stands fairly thus: “ Why 
is the one substance.always attracted to a determinate pole, 
suppose to the negative? Because it is natufally positive. 
But how is it proved that it is naturally positive? Because 
it is attracted to the negative pole.’’ ‘There is no service 
rendered to the hypothesis by this cireular reasoning. 
I shall now submit the evidence against this supposition, 
If 
