led_
from the decomposing mass (518. 519.), not _drawn out by an attraction_
which ceases to act on one particle without any assignable reason, while it
continues to act on another of the same kind: and whether the poles be
metal, water, or air, still the substances are evolved, and are sometimes
set free, whilst at others they unite to the matter of the poles, according
to the chemical nature of the latter, i.e. their chemical relation to those
particles which are leaving the substance under operation.

538. The theory accounts for the _transfer of elements_ in a manner which
seems to me at present to leave nothing unexplained; and it was, indeed,
the phenomena of transfer in the numerous cases of decomposition of bodies
rendered fluid by heat (380. 402.), which, in conjunction with the
experiments in air, led to its construction. Such cases as the former where
binary compounds of easy decomposability are acted upon, are perhaps the
best to illustrate the theory.

539. Chloride of lead, for instance, fused in a bent tube (400.), and
decomposed by platina wires, evolves lead, passing to what is usually
called the negative pole, and chlorine, which being evolved at the positive
pole, is in part set free, and in part combines with the platina. The
chloride of platina formed, being soluble in the chloride of lead, is
subject to decomposition, and the platina itself is gradually transferred
across the decomposing matter, and found with the lead at the negative
pole.

540. Iodide of lead evolves abundance of lead at the negative pole, and
abundance of iodine at the positive pole.

541. Chloride of silver furnishes a beautiful instance, especially when
decomposed by silver wire poles. Upon fusing a portion of it on a piece of
glass, and bringing the poles into contact with it, there is abundance of
silver evolved at the negative pole, and an equal abundance absorbed at the
positive pole, for no chlorine is set free: and by careful management, the
negative wire may be withdrawn from the fused globule as the silver is
reduced there, the latter serving as the continuation of the pole, until a
wire or thread of revived silver, five or six inches in length, is
produced; at the same time the silver at the positive pole is as rapidly
dissolved by the chlorine, which seizes upon it, so that the wire has to be
continually advanced as it is melted away. The whole experiment includes
the action of only two elements, silver and chlori