s the "Liberty Bell" of Independence Hall, in Philadelphia, which
rang when Independence was adopted by Congress. This was founded in
England long before the Revolution and later was melted and founded
again in the United States.

It would not be easy to get on without brass and bronze; but even
these alloys are not so necessary as copper by itself. It is so strong
that it is used in boiler tubes of locomotives, as roofing for
buildings and railroad coaches, in the great pans and vats of the
sugar factories and refineries. A copper ore called "malachite," which
shows many shades of green, beautifully blended and mingled, is used
for the tops of tables. Wooden ships are often "copper-bottomed"; that
is, sheets of copper are nailed to that part of the hull which is
under water in order to prevent barnacles from making their homes on
it, and so lessening the speed of the vessel.

People often say that the latter half of the nineteenth century was
the Age of Steel, because so many new uses for steel were found at
that time. The twentieth century promises to be the Age of
Electricity, and electricity must have copper. Formerly iron was used
for telegraph wires; but it needs much more electricity to carry power
or light or heat or a telegraphic message over an iron wire than one
of copper. Moreover, iron will rust and will not stretch in storms
like copper, and so needs renewing much oftener. Electric lighting and
the telephone are everywhere, even on the summits of mountains and in
mines a mile below the earth's surface. Electric power, if a
waterfall furnishes the electricity, is the cheapest power known. The
common blue vitriol is one form of copper, and to this we owe many of
our electric conveniences. It is used in all wet batteries, and so it
rings our doorbells for us. It also sprays our apple and peach trees,
and is a very valuable article. Indeed, copper in all its forms, pure
and alloyed, is one of our best and most helpful friends.

IX

THE NEW METAL, ALUMINUM

Not many years ago a college boy read about an interesting metal
called "aluminum." It was as strong as iron, but weighed only one
third as much, and moisture would not make it rust. It was made of a
substance called "alumina," and a French chemist had declared that the
clay banks were full of it; and yet it cost as much as silver. It had
been used in France for jewelry and knicknacks, and a rattle of it had
been presented to the baby son of th