N 67._ Explain why women dampen clothes before
ironing them; why crackers are put up in waterproof cartons;
why an oil shoe polish is better than one containing water.

INFERENCE EXERCISE

Explain the following:

421. You can shorten your finger nails by filing them.

422. You can do it more quickly after washing them than
before.

423. After a flashlight picture is taken, the smoke soon
reaches all parts of the room.

424. A jeweler wears a convex lens on his eye when he works
with small objects.

425. Shoemakers soak the leather before half-soling shoes.

426. Lightning often sets fire to houses or trees that it
strikes.

427. The directions on many bottles of medicine and of
preparations for household use say, "Shake well before using."

428. If you set a cold tumbler inside of one that has just
been washed in hot water, the outer one will crack in a few
minutes.

429. A dry cloth hung out at night becomes wet, while a wet
cloth hung out on a clear day dries.

430. Putting cold cream or tallow around the roots of your
finger nails will help to prevent hangnails.

CHAPTER TEN

CHEMICAL CHANGE AND ENERGY

SECTION 46. _What things are made of: Elements._

What is water made of?

What is iron made of?

Is everything made out of dust?

One of the most natural questions in the world is, "What is this
made of?" If we are talking about a piece of bread, the answer is, of
course, "flour, water, milk, shortening, sugar, salt, and yeast." But
what is each of these made of? Flour is made of wheat, and the wheat
is made of materials that the plant gets from the earth, water, and
air. Then what are the earth, water, and air made of? A chemist is
a person who can answer these questions and who can tell what almost
everything is made of. And a strange thing that chemists have found
out is this: Everything in the world is made out of one or more of
about eighty-five simple substances called _elements_.

WHAT AN ELEMENT IS. An element is a substance that is not made of
anything else but itself. Gold is one of the eighty-five elements;
there are no other substances known to man that you can put together
to make gold. It is made of gold and that is all. There is a theory
that maybe all the elements are made of electrons in different
arrangements, or of electrons and one other thing; but we do not know