ion, quicksilver, copper, lead, tin, and other
metals have been discovered. The copper mines being nearest the sea,
are generally worked, the ore being sent to Swansea.

The lofty plateau of Mexico in North America has, from the first, been
celebrated for its rich silver mines, of which there have altogether
existed no less than three thousand, but the larger number of these have
long been unworked. The gold mines of California and of Australia are
too well known to require mention; but we must not forget the rock oil,
concealed for ages in the North American continent. Both the United
States and Canada now yield an abundant supply.

The number of metals discovered beneath the surface, including the
metallic basis of the earth and alkalies, amounts to forty-two, but
metals, commonly so-called, number only twenty-nine. These are
platinum, gold, tungsten, mercury, lead, palladium, silver, bismuth,
uranium, vanadium, copper, cadmium, cobalt, arsenic, nickel, iron,
molybdenum, tin, zinc, antimony, tellurium, manganese, tatiaum,
chromium, columbium, rhodium, iridium, osmium, cerium. Many of these,
however, are so rare, that as yet they are of no practical use. Gold
has been known from the earliest ages, and is found in scales, threads,
grains, and rolled masses, or nuggets, which latter have been discovered
in California and Australia weighing from twenty to thirty pounds, but
the largest of all met with was in Asia, on the southern side of the
Urals.

Large quantities of gold were discovered on a marshy plain which had
been thoroughly turned over, when it was resolved to take down the
buildings in which the gold was washed, and under the very corner of one
of them a lump was found, weighing no less than ninety-six and a-half
pounds troy, and valued at 4000 pounds. Gold has been found in
Scotland, and in the county of Wicklow, Ireland, where about 10,000
pounds worth was picked up in the bed of a river by the inhabitants,
before the Government became aware of its existence. Gold is so
malleable that a single grain can be beaten out to form a gold leaf
covering a surface of fifty-six square inches, and it is so ductile that
the same quantity may be drawn into a wire 500 feet in length. Silver
is found embedded in various rocks, where it occurs in veins, assuming
arborescent or thread-like forms, and occasionally appearing in large
masses. The largest mass found in Europe was brought from Kongsberg, in
Norway, wei