s_, which excited so much attention at the
close of the seventeenth century.

Borri lingered in the prison of St. Angelo till 1695, when he died, in his
eightieth year. Besides _The Key of the Cabinet_, written originally in
Copenhagen, in 1666, for the edification of King Frederick III., he
published a work upon alchymy and the secret sciences, under the title of
_The Mission of Romulus to the Romans_.

INFERIOR ALCHYMISTS OF THE SEVENTEENTH CENTURY.

Besides the pretenders to the philosopher's stone whose lives have been
already narrated, this and the preceding century produced a great number
of writers, who inundated literature with their books upon the subject. In
fact, most of the learned men of that age had some faith in it. Van
Helmont, Borrichius, Kircher, Boerhaave, and a score of others, though not
professed alchymists, were fond of the science, and countenanced its
professors. Helvetius, the grandfather of the celebrated philosopher of
the same name, asserts that he saw an inferior metal turned into gold by a
stranger, at the Hague, in 1666. He says, that, sitting one day in his
study, a man, who was dressed as a respectable burgher of North Holland,
and very modest and simple in his appearance, called upon him, with the
intention of dispelling his doubts relative to the philosopher's stone. He
asked Helvetius if he thought he should know that rare gem if he saw it.
To which Helvetius replied, that he certainly should not. The burgher
immediately drew from his pocket a small ivory box, containing three
pieces of metal, of the colour of brimstone, and extremely heavy; and
assured Helvetius, that of them he could make as much as twenty tons of
gold. Helvetius informs us, that he examined them very attentively; and
seeing that they were very brittle, he took the opportunity to scrape off
a small portion with his thumb-nail. He then returned them to the
stranger, with an entreaty that he would perform the process of
transmutation before him. The stranger replied, that he was not allowed to
do so, and went away. After his departure, Helvetius procured a crucible
and a portion of lead, into which, when in a state of fusion, he threw the
stolen grain from the philosopher's stone. He was disappointed to find
that the grain evaporated altogether, leaving the lead in its original
state.

Some weeks afterwards, when he had almost forgotten the subject, he
received another visit from the stranger. He again entreated