on could be
produced without the aid of the voltaic battery.

[A] The heat need not be raised so much as to make the alkali tarnish
the platina, although if that effect does take place it does not
prevent the ultimate action.

606. When a solution of tartaric or acetic acid was substituted, in this
mode of preparation, for the sulphuric acid, still the plate was found to
acquire the same power, and would often produce explosion in the mixed
gases; but the strong sulphuric acid was most certain and powerful.

607. If borax, or a mixture of the carbonates of potash and soda, be fused
on the surface of a platina plate, and that plate be well-washed in water,
it will be found to have acquired the power of combining oxygen and
hydrogen, but only in a moderate degree; but if, after the fusion and
washing, it be dipped in the hot sulphuric acid (601.), it will become very
active.

608. Other metals than platina were then experimented with. Gold and
palladium exhibited the power either when made the positive pole of the
voltaic battery (570.), or when acted on by hot oil of vitriol (601.). When
palladium is used, the action of the battery or acid should be moderated,
as that metal is soon acted upon under such circumstances. Silver and
copper could not be made to show any effect at common temperatures.

* * * * *

609. There can remain no doubt that the property of inducing combination,
which can thus be conferred upon masses of platina and other metals by
connecting them with the poles of the battery, or by cleansing processes
either of a mechanical or chemical nature, is the same as that which was
discovered by Doebereiner[A], in 1823, to belong in so eminent a degree to
spongy platina, and which was afterwards so well experimented upon and
illustrated by MM. Dulong and Thenard[B], in 1823. The latter philosophers
even quote experiments in which a very fine platina wire, which had been
coiled up and digested in nitric, sulphuric, or muriatic acid, became
ignited when put into a jet of hydrogen gas[C]. This effect I can now
produce at pleasure with either wires or plates by the processes described
(570. 601. 605.); and by using a smaller plate cut so that it shall rest
against the glass by a few points, and yet allow the water to flow off
(fig. 59.), the loss of heat is less, the metal is assimilated somewhat to
the spongy state, and the probability of failure almost entirely removed.