quickly in water that is
boiling violently than in water that is boiling gently.

304. When you brush your hair on a winter morning, it
sometimes stands up and flies apart more and more as you
continue to brush it.

305. You cannot see a person clearly through a ground-glass
window, although it lets most of the light through.

306. There is a layer of coarse, _light-colored_ gravel over
the tar on roofs, to keep the tar from melting.

307. It is very easy to slip on a well-waxed hardwood floor.

308. If you have a silver filling in one of your teeth and
you touch the filling with a fork or spoon, you get a slight
shock.

309. You can shake a thing down into a bottle when it will not
slip down by itself.

310. If you rub a needle across one pole of a magnet three or
four times in the same direction, then float it on a cork in
water one end of the needle will point north.

SECTION 34. _Conduction of electricity._

How does electricity travel?

Why do you get a shock if your hands are wet when you touch a
live wire?

If you were to use a piece of string instead of a copper wire to go
from one pole of a battery to another or to spin between the poles
of the magnet of the dynamo, you could get no flow of electricity to
speak of. Electrons do not flow through string easily, but they flow
through a copper wire very easily. Anything that carries, or conducts,
electricity well is called a _good conductor_. Anything that
carries it poorly is called a _poor conductor_. Anything that
allows practically no electricity to pass through it is called an
_insulator_.

EXPERIMENT 65.[5] Turn on an electric lamp. Turn it off by
opening the knife switch. Cover the blade of the knife switch
with a fold of paper and close it. Will the lamp glow? Try a
fold of dry cloth; a fold of the same cloth wet. Connect the
blade to the slot with a piece of iron; with a piece of glass;
with porcelain; with rubber; with dry wood; with wood that is
soaking wet; with a coin. Which of these are good conductors
of electricity? Which could be used as insulators?

[Footnote 5: Read footnote, page 226, before doing this experiment.]

[Illustration: FIG. 119. Electricity flows through the coin.]

HOW YOU CAN GET AN ELECTRICAL SHOCK. A person's body is not a very
good conductor of electricity, but will conduct it somewhat. When
ele