dingly luminous and bright upon both surfaces of
the charcoal, resembling the brightness of the voltaic discharge on such
surfaces. When the discharge of the unretarded electricity was taken upon
charcoal, it was bright upon both the surfaces, (in that respect resembling
the voltaic spark,) but the noise was loud, sharp, and ringing.

335. I have assumed, in accordance, I believe, with the opinion of every
other philosopher, that atmospheric electricity is of the same nature with
ordinary electricity (284.), and I might therefore refer to certain
published statements of chemical effects produced by the former as proofs
that the latter enjoys the power of decomposition in common with voltaic
electricity. But the comparison I am drawing is far too rigorous to allow
me to use these statements without being fully assured of their accuracy;
yet I have no right to suppress them, because, if accurate, they establish
what I am labouring to put on an undoubted foundation, and have priority to
my results.

336. M. Bonijol of Geneva[A] is said to have constructed very delicate
apparatus for the decomposition of water by common electricity. By
connecting an insulated lightning rod with his apparatus, the decomposition
of the water proceeded in a continuous and rapid manner even when the
electricity of the atmosphere was not very powerful. The apparatus is not
described; but as the diameter of the wire is mentioned as very small, it
appears to have been similar in construction to that of Wollaston (327.);
and as that does not furnish a case of true polar electro-chemical
decomposition (328.), this result of M. Bonijol does not prove the identity
in chemical action of common and voltaic electricity.

[A] Bibliotheque Universelle, 1830, tome xlv. p. 213.

337. At the same page of the Bibliotheque Universelle, M. Bonijol is said
to have decomposed, _potash_, and also chloride of silver, by putting them
into very narrow tubes and passing electric sparks from an ordinary machine
over them. It is evident that these offer no analogy to cases of true
voltaic decomposition, where the electricity only decomposes when it is
_conducted_ by the body acted upon, and ceases to decompose, according to
its ordinary laws, when it passes in sparks. These effects are probably
partly analogous to that which takes place with water in Pearson's or
Wollaston's apparatus, and may be due to very high temperature acting on
minute portions of matter; or th