156 Prof. A. de la Rive’s Memoir of 
those substances, either simple, like sulphur and phosphorus, 
or compound, such as the-periodids and perchlorids of tin, and 
many others, which continue isolators when fused as well as in 
the solid state. In this first investigation, notwithstanding a 
great number of experiments in which he employed the influence 
of heat and of electricity of high tension in, the study of the . 
conductive power of solid bodies, he did not-succeed in deter- 
mining very accurately the coriditions of electrical conduc- 
tibility; he only ascertained that, with gme-exception, which he 
justly regards as only apparent, there is not a solid body which, 
on becoming conductive by its passage to a liquid state, is not 
decomposed by the electrical current. We may add, so as not 
to return to the subject, that Faraday sometimes had doubts 
upon this point, and he even thought that water could conduct 
electricity without being decomposed. Now experiment shows 
that in all cases, even those which appear most favorable to 
this opinion, electricity cannot be transmitted under any form 
through a compound liquid body, without this body undergoing 
electrochemical decomposition. 
As to the causes of conductibility, they are still far from 
being known; when we see bodiés, such as the gases, becoming 
conductors when greatly rarefied, whilst under the ordinary pres- 
sure they are perfect i 
this difference, as well as so many others presented in this re- 
spect by solid and liquid bodies, is due to the fact that we have 
not yet a correct notion of the molecular constitution of bodies. 
Perhaps the recent theories of several physicists, particularly 
that of Clausius, who regards the particles of bodies as being 
- in a constant state of movement, may succeed in elucidating 
this subject, which is still so mysterious. Faraday himself 
fully foreseen this relation between electrical conductibility and » 
the ideas which we may form as to the nature of matter. In 
an 
nsulators, we are compelled to come to 
the conclusion that the impossibility that we find of explaining: 
po . 
experimental basis, that, in the theory according to which a 
Sealtincs : : | .p 
arated from each other by larger or er intermolecular m~- 
