Antonio Exili, an Italian, like many other alchemists of that period,
had spent years in search of the philosopher's stone and the elixir
of life. His vain experiments to transmute the baser metals into gold
reduced him to poverty and want. His quest after these secrets had led
him to study deeply the nature and composition of poisons and their
antidotes. He had visited the great universities and other schools of
the continent, finishing his scientific studies under a famous German
chemist named Glaser. But the terrible secret of the agua tofana and of
the poudre de succession, Exili learned from Beatrice Spara, a Sicilian,
with whom he had a liaison, one of those inscrutable beings of the
gentle sex whose lust for pleasure or power is only equalled by the
atrocities they are willing to perpetrate upon all who stand in the way
of their desires or their ambition.

To Beatrice Spara, the secret of this subtle preparation had come
down like an evil inheritance from the ancient Candidas and Saganas of
imperial Rome. In the proud palaces of the Borgias, of the Orsinis, the
Scaligers, the Borromeos, the art of poisoning was preserved among the
last resorts of Machiavellian statecraft; and not only in palaces, but
in streets of Italian cities, in solitary towers and dark recesses of
the Apennines, were still to be found the lost children of science,
skilful compounders of poisons, at once fatal and subtle in their
operation,--poisons which left not the least trace of their presence in
the bodies of their victims, but put on the appearance of other and more
natural causes of death.

Exili, to escape the vengeance of Beatrice Spara, to whom he had proved
a faithless lover, fled from Naples, and brought his deadly knowledge
to Paris, where he soon found congenial spirits to work with him in
preparing the deadly poudre de succession, and the colorless drops of
the aqua tofana.

With all his crafty caution, Exili fell at last under suspicion of
the police for tampering in these forbidden arts. He was arrested, and
thrown into the Bastile, where he became the occupant of the same cell
with Gaudin de St. Croix, a young nobleman of the Court, the lover of
the Marchioness de Brinvilliers, for an intrigue with whom the Count
had been imprisoned. St. Croix learned from Exili, in the Bastile, the
secret of the poudre de succession.

The two men were at last liberated for want of proof of the charges
against them. St. Croix set up a la