to the air, and appears to be equally permanent
with that of pure gold; the metal is indestructible by fire. Platina
is capable of being alloyed with all metals; is fused with difficulty,
but by great labor may be rendered malleable: it is also the heaviest
metal, being 21 times heavier than water.

_Permanent_, lasting.

Are there any other Metals besides those already mentioned?

In addition to the metals known and used by the ancients, the chemical
science of later ages has, by decomposing other earths, added more
than thirty to the number of metals, some of them more curious than
useful; several of these are lighter than water. All the metals
possess different and distinct properties from each other. They are
divided into two classes, the malleable and the brittle metals. These
last may be again divided into two others,--namely, those which are
easily, and those which are with difficulty fused.

What do you mean by Metallurgy?

The art of obtaining metals from their ores, comprising the processes
of assaying, refining, smelting, &c. By assaying is meant, the
particular manner of examining an ore or mixed metal, according to its
nature, so as to discover not only what metals and what proportions of
metal may be obtained from it, but also what other mineral substances
or earths may be contained in it.

What do the terms Refining and Smelting signify?

Refining is the art of rendering the metal free from all impurities.
Smelting means the melting of a metal from its ore in a smelting
furnace, in order to separate the metallic parts from the sulphur,
arsenic, and the earthy and stony substances with which they may be
combined.

What is Sulphur?

An inflammable, fossil substance, of a dry, solid, friable nature,
melting with a small proportion of heat;--when fired in the open air,
burning almost entirely away with a blue flame and noxious vapor. It
is abundantly diffused in many places, especially where metallic
minerals are found; but more particularly in those districts where
subterranean fires and volcanoes exist. It is also found combined with
many different substances.

Describe the nature of Sulphur, and the places where it is mostly
found.

Sulphur almost pure, called native or virgin sulphur, is found in
volcanoes and grottoes, in the form of transparent crystals; but the
greatest quantity which exists naturally is combined with metals in
ores. Sulphur is both fusible and volatile,--