which he called isomorphism.

Here, then, were two utterly novel and independent sets of
empirical facts which harmonize strangely with the supposition
that substances are composed of chemical atoms of a determinate
weight. This surely could not be coincidence--it tells of law.
And so as soon as the claims of Dulong and Petit and of
Mitscherlich had been substantiated by other observers, the laws
of the specific heat of atoms, and of isomorphism, took their
place as new levers of chemical science. With the aid of these
new tools an impregnable breastwork of facts was soon piled about
the atomic theory. And John Dalton, the author of that theory,
plain, provincial Quaker, working on to the end in
semi-retirement, became known to all the world and for all time
as a master of masters.


HUMPHRY DAVY AND ELECTRO-CHEMISTRY

During those early years of the nineteenth century, when Dalton
was grinding away at chemical fact and theory in his obscure
Manchester laboratory, another Englishman held the attention of
the chemical world with a series of the most brilliant and widely
heralded researches. This was Humphry Davy, a young man who had
conic to London in 1801, at the instance of Count Rumford, to
assume the chair of chemical philosophy in the Royal Institution,
which the famous American had just founded.

Here, under Davy's direction, the largest voltaic battery yet
constructed had been put in operation, and with its aid the