Glen Martin, age 10, of Gallup, N.M., for his question:

HOW IS DRY ICE MADE?

One of the fine products used for keeping perishable products cool while being shipped is a refrigerant called dry ice.

Dry Ice is so named because it goes directly from a cold, solid state to a gaseous state at room temperature. You won't find a puddle of water as you do when regular ice melts.

Dry Ice is actually the commercial name for solid carbon dioxide. Carbon dioxide gas, found everywhere in the earth's atmosphere, is first liquefied by using large compressors.    

The liquid is then stored in steel cylinders and when the nozzle is finally opened, the escaping liquid is confined to a larger container.

In the larger container, some of the liquid carbon dioxide evaporates again to gas, thus cooling the chamber. When the container has been cooled to the freezing point of carbon dioxide, the remaining liquid freezes. It is then packaged and used commercially.

There are a number of important things to remember if you come into contact with Dry Ice. First of all, never handle it without wearing gloves or using a pair of tongs. The product has a temperature of minus 110 degrees Fahrenheit ¬and that's cold enough to do serious injury to your hand.

Dry Ice is cold enough to snuff out a burning candle. You can prove this by placing several pieces of Dry Ice in a pitcher with two inches of water. A cloud will form immediately since the carbon dioxide gas is so cold it causes the water vapor in the air to condense. Now tilt the pitcher over a burning candle and the flame will go out as the gas, which is heavier than the air, tumbles over the side and down to the blaze.    

There are a number of other interesting experiments that can be done with Dry Ice. Perhaps your teacher in school can show you some of them. But the important thing to remember when working with the product is that extreme caution is absolutely necessary.