Carbon.

Carbon is important to all forms of life. It makes up less than 1 percent of all matter, but everything that lives or has lived contains this element. The bodies of all living things are made up of compounds containing carbon, and where it found in any quantity in the earth, life has probably existed.

Plants get carbon from carbon dioxide gas of the air and use it in building up their roots, stems, and leaves. Animals get it for food from plants. At the same time, carbon dioxide is being returned to the air by animals when they breathe, and by plants when they decay.

Of all the forms of carbon, the best-known, and perhaps the most valuable to man, is coal. Coal is about four-fifths carbon, the rest being hydrogen and other elements. The attraction between carbon and oxygen is almost like that between a magnet and iron.

This is one of the reasons why coal is so valuable. When coal is put into fire, its element, particularly its carbon, burn or combine with the oxygen in the air. This burning produces heat energy, which used by man in many ways.

Carbon atoms can attach themselves to each other and to the atoms of other elements. They combine in many different ways to from many carbon compounds. One of the simplest one is carbon dioxide, which given off into the atmosphere when carbon burns in oxygen. Carbon monoxide, a poisonous gas, forms when carbon burns where there is not enough oxygen.