there not some that could fortify the memory,
others destroy it; some re-enforce the spirits, some impart dulness,
and some, which were highly prized, that could secure a return of love?
It had been long known that both natural and artificial waters can
permanently affect the health, and that instruments may be made to
ascertain their qualities. Zosimus, the Panopolitan, had described in
former times the operation of distillation, by which water may be
purified; the Arabs called the apparatus for conducting that experiment
an alembic. His treatise on the virtues and composition of waters was
conveyed under the form of a dream, in which there flit before us
fantastically white-haired priests sacrificing before the altar;
cauldrons of boiling water, in which there are walking about men a span
long; brazen-clad warriors in silence reading leaden books, and sphinxes
with wings. In such incomprehensible fictions knowledge was purposely,
and ignorance conveniently concealed.

[Sidenote: The Arabs originate scientific chemistry.]

The practical Arabs had not long been engaged in these fascinating but
wild pursuits, when results of very great importance began to appear. In
a scientific point of view, the discovery of the strong acids laid the
true foundation of chemistry; in a political point of view, the
invention of gunpowder revolutionized the world.

[Sidenote: Gunpowder and fireworks.]

There were several explosive mixtures. Automatic fire was made from
equal parts of sulphur, saltpetre, and sulphide of antimony, finely
pulverized and mixed into a paste, with equal parts of juice of the
black sycamore and liquid asphaltum, a little quick-lime being added. It
was directed to keep the material from the rays of the sun, which would
set it on fire.

[Sidenote: Incombustible men.]

Of liquid or Greek fire we have not a precise description, since the
knowledge of it was kept at Constantinople as a state secret. There is
reason, however, to believe that it contained sulphur and nitrate of
potash mixed with naphtha. Of gunpowder, Marcus Graecus, whose date is
probably to be referred to the close of the eighth century, gives the
composition explicitly. He directs us to pulverize in a marble mortar
one pound of sulphur, two of charcoal, and six of saltpetre. If some of
this powder be tightly rammed in a long narrow tube closed at one end,
and then set on fire, the tube will fly through the air: this is
clearly the rocket. He