Robert Pickergin, age 10, of Winnipeg, Man., Canada, for his question:

HOW DO THEY MAKE GLASS?

Glass is used to make bottles and lenses, windowpanes and windshields and hundreds of other items in our daily lives. With all this glass around, you might suspect that it is easy to make. But this is not so. The basic ingredients must be heated to terrifically high temperatures to make them melt and fuse  together. This requires a very hot furnace, which uses up a fantastic amount of energy.

A glass making factory has thousands of recipes for making different kinds of glass. But the main ingredients are the same in all recipes. Most of the raw material is sand, with a high content of silica. About 15% is soda and about 9$ is lime. Other ingredients are added in small amounts to make special glass for special jobs. A big melting pot may hold more than 100 tons. The furnace is hot enough to produce a temperature of 2,700 degrees Fahrenheit. At this point the ingredients melt and merge together to form a soft, tacky substance. When it cools, it becomes hard, brittle glass