cut out. They are then put together and
varnished. While still on the last, they are dipped into a tank of
varnish and vulcanized--a very simple matter now that Goodyear has
shown us how, for they are merely left in large, thoroughly heated
ovens for eight or ten hours. The rubber shoe or boot is now elastic,
strong, waterproof, ready for any temperature, and so firmly cemented
together with rubber cement that it is practically all in one piece.

During the last few years there have been frequent calls from various
charities for old rubber overshoes, pieces of rubber hose, etc. These
are of considerable value in rubber manufacturing. They are run
through a machine which tears them to shreds, then through a sort of
fanning-mill which blows away the bits of lining. Tiny pieces of iron
may be present from nails or rivets; but these are easily removed by
magnets. This "reclaimed" rubber is powdered and mixed with the new,
and for some purposes the mixture answers very well. Imitation rubber
has been made by heating oil of linseed, hemp, maize, etc., with
sulphur; but no substitute for rubber is a success for all uses.

[Illustration: _Courtesy U. S. Tire Co._

HOW RUBBER GOES THROUGH THE FACTORY

Splitting Para biscuits, mixing the rubber, rolling the rubber fabric
on cylinders, and building tires on the tire machines.]

There are many little conveniences made of rubber which we should
greatly miss, such as the little tips put into pencil ends for erasing
pencil marks. These are made by filling a mould with rubber. Rubber
corks are made in much the same manner. Tips for the legs of chairs
are made in a two-piece mould larger at the bottom than at the top,
and with a plunger that nearly fits the small end. Often on chair tips
and in the cup-shaped eraser that goes over the ends of some pencils
you can see the "fin," as the glassworkers call it, where the two
pieces of the mould did not exactly fit. Rubber cannot be melted and
cast in moulds like iron, but it can be gently heated and softened,
and then pressed into a mould. Rubber stamps are made in this way. The
making of rubber heels and soles is now a large industry; hose for
watering and for vacuum and Westinghouse brakes is made in increasing
quantities. The making of rubber tires for automobiles and carriages
is an important industry. The enormous and increasing use of
electricity requires much use of rubber as an insulator. Rubber gloves
will protect an electrica