All living things need nitrogen in a form their bodies can use. It is important to plants and animals as well as to humans. It is a necessary part of the protein substance which is man's body-building material. Without this substance, no one could grow or repair d...

Of all the chemical elements known to man, perhaps the most inter­esting one is carbon. Did you know, for example, that in the form of crystal it gives us one of our most valuable gems, the diamond? As graph­ite, carbon forms the lead of lead pencils. And coal, the ...

Fog, dew, and clouds are all related. In fact, just one change in the conditions-such as the presence or absence of air currents-could make the difference as to whether there will be fog, dew, or clouds. Let's see why this is so, and why fogs appear in cer­tain...

Would the world really be so much better off if there were no dust? The answer is: in some ways-yes; in some ways-no. What is dust, anyway? It consists of particles of earth, or other solid matter, which are light enough to be raised and carried by th...

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 exte...

You look out on the street or road and you see water. An hour later in bright sunshine, it is gone! Or wet clothes are hung out on a line, and by the end of the day, they are dry. Where did the water go?

We say the water evaporates...

As we read about man's exploration of the moon and the planets, we often come across the question of an atmosphere. Do other planets have an atmosphere, too?

As far as scientists know, there is no other planet or star that has an atmosph...

When a stream or river plunges over a wall of rock called a cliff or a precipice, we have a waterfall. If the waterfall is of great size, it is called a cataract. Where the rock wall is steeply slanted rather than vertical, the rushing water is called a cascade. Somet...

In an artesian well, the water can leap high into the air like a geyser from its prison far below the surface of the earth. The name comes from the Artois region in northern France where the first European well of this kind was drilled more than 800 years ago. Artes...

For as far back as we can go in the history of man, we find records or tales, or legends, about great floods. The reason for this is that there have always been floods. In fact, primitive man deliberately settled in the valleys that were in the paths of floods-be­cause...