and the _flash_ before the eyes; but I could obtain no evidence of chemical
decomposition.

57. The various experiments of this section prove, I think, most completely
the production of electricity from ordinary magnetism. That its intensity
should be very feeble and quantity small, cannot be considered wonderful,
when it is remembered that like thermo-electricity it is evolved entirely
within the substance of metals retaining all their conducting power. But an
agent which is conducted along metallic wires in the manner described;
which whilst so passing possesses the peculiar magnetic actions and force
of a current of electricity; which can agitate and convulse the limbs of a
frog; and which, finally, can produce a spark[A] by its discharge through
charcoal (32.), can only be electricity. As all the effects can be produced
by ferruginous electro-magnets (34.), there is no doubt that arrangements
like the magnets of Professors Moll, Henry, Ten Eyke, and others, in which
as many as two thousand pounds have been lifted, may be used for these
experiments; in which case not only a brighter spark may be obtained, but
wires also ignited, and, as the current can pass liquids (23.), chemical
action be produced. These effects are still more likely to be obtained when
the magneto-electric arrangements to be explained in the fourth section are
excited by the powers of such apparatus.

[A] For a mode of obtaining the spark from the common magnet which I
have found effectual, see the Philosophical Magazine for June 1832, p.
5. In the same Journal for November 1834, vol. v. p. 349, will be
found a method of obtaining the magneto-electric spark, still simpler
in its principle, the use of soft iron being dispensed with
altogether.--_Dec. 1838._

58. The similarity of action, almost amounting to identity, between common