Most of us think of air as being “nothing,” but air is definitely “something,” if it is matter made up of certain gases. A gas does not have a definite size or shape, but it takes up space.

The great ocean of air that surrounds the earth and extends for many miles upward is attracted and held to the earth by gravity. Thus air has weight. And since air is everywhere about us, it adds weight to every object it fills. For example, there is a small amount of air in a volley ball. If you were to weigh two such balls, with the air let out of one of them, you would find it’s lighter than the other.