Faraday as a Discoverer HTML version

Chapter 7
Origin of power in the voltaic pile.
In one of the public areas of the town of Como stands a statue with no inscription on its
pedestal, save that of a single name, 'Volta.' The bearer of that name occupies a place for
ever memorable in the history of science. To him we owe the discovery of the voltaic
pile, to which for a brief interval we must now turn our attention.
The objects of scientific thought being the passionless laws and phenomena of external
nature, one might suppose that their investigation and discussion would be completely
withdrawn from the region of the feelings, and pursued by the cold dry light of the
intellect alone. This, however, is not always the case. Man carries his heart with him into
all his works. You cannot separate the moral and emotional from the intellectual; and
thus it is that the discussion of a point of science may rise to the heat of a battle-field. The
fight between the rival optical theories of Emission and Undulation was of this fierce
character; and scarcely less fierce for many years was the contest as to the origin and
maintenance of the power of the voltaic pile. Volta himself supposed it to reside in the
Contact of different metals. Here was exerted his 'Electro-motive force,' which tore the
combined electricities asunder and drove them as currents in opposite directions. To
render the circulation of the current possible, it was necessary to connect the metals by a
moist conductor; for when any two metals were connected by a third, their relation to
each other was such that a complete neutralisation of the electric motion was the result.
Volta's theory of metallic contact was so clear, so beautiful, and apparently so complete,
that the best intellects of Europe accepted it as the expression of natural law.
Volta himself knew nothing of the chemical phenomena of the pile; but as soon as these
became known, suggestions and intimations appeared that chemical action, and not
metallic contact, might be the real source of voltaic electricity. This idea was expressed
by Fabroni in Italy, and by Wollaston in England. It was developed and maintained by
those 'admirable electricians,' Becquerel, of Paris, and De la Rive, of Geneva. The
Contact Theory, on the other hand, received its chief development and illustration in
Germany. It was long the scientific creed of the great chemists and natural philosophers
of that country, and to the present hour there may be some of them unable to liberate
themselves from the fascination of their first-love.
After the researches which I have endeavoured to place before you, it was impossible for
Faraday to avoid taking a side in this controversy. He did so in a paper 'On the Electricity
of the Voltaic Pile,' received by the Royal Society on the 7th of April, 1834. His position
in the controversy might have been predicted. He saw chemical effects going hand in
hand with electrical effects, the one being proportional to the other; and, in the paper now
before us, he proved that when the former was excluded, the latter were sought for in
vain. He produced a current without metallic contact; he discovered liquids which,
though competent to transmit the feeblest currents--competent therefore to allow the