Christopher Kingsbury, age 12, of  Ottowa, Canada, for his question:

What is ozone?

Sometimes after a thunderstorm there is a strange smell in the air, This odor comes from ozone which is created from oxygen in the atmosphere by powerful bolts of lightning. Normal oxygen occurs in molecules of two identical atoms. These double atoms in oxygen dislike to be torn apart and it is believed that a particle of ozone is‑composed of three identical molecules of oxygen.

The energy required to make one particle of ozone from three oxygen molecules is equal to 68,800 calories. in food value, this is enough energy to keep you active for a couple of .months. Ozone tends to break down readily into oxygen and, when it does so, this same amount of energy is released, From this fact we get the idea that ozone is a very powerful gas, and so it is. It can do all sorts of jobs in industry,

This is a gas, ozone has a faint bluish tinge. If you have smelled it after a thunderstorm you know it has an unpleasant odor, rather like chlorine. In fact the name ozone is coined from a Greek word meaning smell. It may be harmful to the lungs in large, concentrated doses.

The normal amount of ozone in the air, however, does no harm and may do some good. It is a great germ killer. i~part from lightning, ozone may also be formed in the air by the ultraviolet rays of sunlight. It is also formed when large amounts of water evaporate. This is why we are 'told that we breathe large amounts of ozone at the seashore and on the ocean. The tangy smell we get at the beach, however, it more likely to come from seaweed and decaying fish than from ozone.

At ordinary temperatures ozone soon breaks down into oxygen. There is very little of it in the lower atmosphere, though it is more concentrated and endures longer in the cool, higher layers of the air.

As an air purifier ozone has its drawbacks. In large doses it may kill the people along with the germs. His a water purifier it is excellent. The water supply for Paris, France and some of the water for Philadelphia is purified by ozone. When it has killed the harmful germs it breaks down into harmless oxygen,

Ozone is one of the best of all color removers. It is used to remove dyes and to bleach sugar and flour. It is especially valuable for bleaching flour that has to be stored. For, as it bleaches, it kills all the tiny germs, bugs, and their eggs. Long before the flour is to be used the powerful ozone has broken down into oxygen.

Recently a new job was found for ozone. It is a powerful though expensive, agent for curing wood. This job takes three or four months by the usual methods. Ozone does the job in one month,