is known as the "Bessemer process" was invented. One great
difficulty in the manufacture of steel was to leave just the right
amount of carbon in the iron. Bessemer simply took it all out, and
then put back exactly what was needed. Molten iron, tons and tons of
it, is run into an immense pear-shaped vessel called a "converter."
Fierce blasts of air are forced in from below. These unite with the
carbon and destroy it. There is a roar, a clatter, and a clang.
Terrible flames of glowing red shoot up. Suddenly they change from red
to yellow, then to white; and this is the signal that the carbon has
been burned out. The enormously heavy converter is so perfectly poised
that a child can move it. The workmen now tilt it and drop in whatever
carbon is needed. The molten steel is poured into square moulds,
forming masses called "blooms," and is carried away. More iron is put
into the converter, and the work begins again.

The Bessemer process makes enormous masses of steel and makes it very
cheaply; but it has one fault--it is too quick. The converter roars
away for a few minutes, till the carbon and other impurities are
burned out; and the men have no control over the operation. In what is
called the "open-hearth" process, pig iron, scrap iron, and ore are
melted together with whatever other substances may be needed to make
the particular kind of steel desired. This process takes much longer
than the Bessemer, but it can be controlled. Open-hearth steel is more
homogeneous,--that is, more nearly alike all the way through,--and is
better for some purposes, while for others the Bessemer is preferred.

Steel is hard and strong, but it has two faults. A steel bar will
stand a very heavy blow and not break, but if it is struck gently many
thousand times, it sometimes crystallizes and may snap. A steel rail
may carry a train for years and then may crystallize and break and
cause a wreck. Inventors are at work discovering alloys to prevent
this crystallization. The second fault of steel is that it rusts and
loses its strength. That is why an iron bridge or fence must be kept
painted to protect it from the moisture in the air.

If all the iron that is in use should suddenly disappear, did you ever
think what would happen? Houses, churches, skyscrapers, and bridges
would fall to the ground. Railroad trains, automobiles, and carriages
would become heaps of rubbish. Ships would fall apart and become only
scattered planks floating on the