that of the latter 0.49742 of a grain. Oxygen, as you know, unites
with hydrogen in the proportion of 8 to 1, to form water. Calling
the equivalent, or as it is sometimes called, the atomic weight of
hydrogen 1, that of oxygen is 8; that of water is consequently 8 + 1
or 9. Now if the quantity of water decomposed in Faraday's
experiment be represented by the number 9, or in other words by the
equivalent of water, then the quantity of tin liberated from the
fused chloride is found by an easy calculation to be 57.9, which is
almost exactly the chemical equivalent of tin. Thus both the water
and the chloride were broken up in proportions expressed by their
respective equivalents. The amount of electric force which wrenched
asunder the constituents of the molecule of water was competent,
and neither more nor less than competent, to wrench asunder the
constituents of the molecules of the chloride of tin. The fact is
typical. With the indications of his voltameter he compared the
decompositions of other substances, both singly and in series.
He submitted his conclusions to numberless tests. He purposely
introduced secondary actions. He endeavoured to hamper the
fulfilment of those laws which it was the intense desire of his mind
to see established. But from all these difficulties emerged the
golden truth, that under every variety of circumstances the
decompositions of the voltaic current are as definite in their
character as those chemical combinations which gave birth to the
atomic theory. This law of Electro-chemical Decomposition ranks,
in point of importance, with that of Definite Combining Proportions
in chemistry.

Footnotes to Chapter 6

[1] I copy these words from the printed abstract of a Friday