sing before him and around him are leading him gradually, but surely,
to results of incalculable importance in relation to the philosophy of
the voltaic pile.

He had always some great object of research in view, but in the pursuit
of it he frequently alighted on facts of collateral interest, to examine
which he sometimes turned aside from his direct course. Thus we find the
series of his researches on electrochemical decomposition interrupted
by an inquiry into 'the power of metals and other solids, to induce the
combination of gaseous bodies.' This inquiry, which was received by the
Royal Society on Nov. 30, 1833, though not so important as those
which precede and follow it, illustrates throughout his strength as an
experimenter. The power of spongy platinum to cause the combination of
oxygen and hydrogen had been discovered by Dobereiner in 1823, and had
been applied by him in the construction of his well-known philosophic
lamp. It was shown subsequently by Dulong and Thenard that even a
platinum wire, when perfectly cleansed, may be raised to incandescence
by its action on a jet of cold hydrogen.

In his experiments on the decomposition of water, Faraday found that
the positive platinum plate of the decomposing cell possessed in
an extraordinary degree the power of causing oxygen and hydrogen to
combine. He traced the cause of this to the perfect cleanness of
the positive plate. Against it was liberated oxygen, which, with the
powerful affinity of the 'nascent state,' swept away all impurity from
the surface against which it was liberated. The bubbles of gas liberated
on one of the platinum plates or wires of a decomposing cell are always
much smaller, and they rise in much more rapid succession than those
from the other. Knowing that oxygen is sixteen times heavier than
hydrogen, I have more than once concluded, and, I fear, led others
into the error of concluding, that the smaller and more quickly rising
bubbles must belong to the lighter gas. The thing appeared so obvious
that I did not give myself the trouble of looking at the battery, which
would at once have told me the nature of the gas. But Faraday would
never have been satisfied with a deduction if he could have reduced it
to a fact. And he has taught me that the fact here is the direct reverse
of what I supposed it to be. The small bubbles are oxygen, and their
smallness is due to the perfect cleanness of the surface on which they
are liberated. The hydro