86 Faraday's Researches

it by pure gold. Then a number of glass tubes were prepared:
they were about nine or ten inches in length, five-eighths of an
inch in internal diameter, were sealed hermetically at one

Fig. 17.

•extremity; and were graduated. Into these tubes was put a
mixture of two volumes of hydrogen and one of oxygen, at the
water pneumatic trough, and when one of the plates described
had been connected with the positive or negative pole of the
voltaic battery for a given time, or had been otherwise prepared,
it was introduced through the water into the
gas within the tube; the whole set aside in a
test-glass (fig. 18), and left for a longer or
shorter period, that the action might be
observed.

306. The following result may be given as an
illustration of the phenomenon to be investi-
gated. Diluted sulphuric acid, of the specific
gravity 1.336, was put into a glass jar, in which
was placed also a large platina plate, con-
nected with the negative end of a voltaic
battery of forty pairs of four-inch plates, with
double coppers, and moderately charged. One
of the plates above described (305) was then
connected with the positive extremity, and im-
mersed in the same jar of acid for five minutes,
after which it was separated from the battery,
washed in distilled water and introduced
through the water of the pneumatic trough into
a tube containing the mixture of oxygen and
hydrogen (305). The volume of gases immediately began to
lessen, the diminution proceeding more and more rapidly until
about three-fourths of the mixture had disappeared. The
upper end of the tube became quite warm, the plate itself so
hot that the water boiled as it rose over it; and in less than a
minute a cubical inch and a half of the gases were gone, having
been combined by the power of the platina, and converted into
water.

307. This extraordinary influence acquired by the platina at
the positive pole of the pile, is exerted far more readily and

Fig. 18.f the quantities evolved in the cases of electro-