Tommy Harrington, age 14, of McAllen, Tex., for his question:

WHAT IS GLYCERIN?

Glycerin is a colorless, thick, sweet liquid that was first discovered by the splitting or saponification of fats. It is also called glycerol.

First to discover the material was a Swedish chemist named Carl Scheele. He made the first glycerol from olive oil way back in 1783.

The material is used to make synthetic resins that harden paints. It is also used to make ice cream, candy and icings smooth and creamy as well as to make cosmetics and toothpaste smooth.

The chemical industry uses glycerol to make sealing compounds and antifreeze. It is also used to make a powerful explosive that is used to make dynamite and gunpowder.

Air brakes, electrical equipment and oil refining machinery are often lubricated with glycerol.

Most glycerol is a by product of soap making.