oincidence--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 brilliant
young experimenter was expected almost to perform miracles. And indeed
he scarcely disappointed the expectation, for with the aid of his
battery he transformed so familiar a substance as common potash into
a metal which was not only so light that it floated on water, but
possessed the seemingly miraculous property of bursting into flames as
soon as it came in contact with that fire-quenching liquid. If this
were not a miracle, it had for the popular eye all the appearance of the
miraculous.

What Davy really had done was to decompose the potash, which hitherto
had been supposed to be elementary, liberating its oxygen, and thus
isolating its metallic base, which he named potassium. The same
thing was done with soda, and the closely similar metal sodium was
discovered--metals of a unique type, possessed of a strange avidity for
oxygen, and capable of seizing on it even when it is bound up in the
molecules of water. Considered as mere curiosities, these discoveries
were interesting, but aside from that they were of great theoretical
importance, because they showed the compound nature of some familiar
chemicals that had been regarded as elements. Several other elementary
earths met the same fate when subjected to the electrical influence;