Roy E. Love, age 10, of Arvida, Quebec, Canada, for his question:

Who first discovered glass?

Nobody knows who first discovered how to make glass or when it happened. But trying to solve this mystery is very interesting. Archeologists find their evidence in the buried remains of ancient civilizations. They found glass mirrors in Roman ruins, beautiful glass goblets in the tombs of the pharoahs and even older glass ¬coated beads in long buried cities of Mesopotamia. Each finding helps to trace the story another step into the past.

Maybe you thought that the Age of Plastics began in modern times. If so, then you forgot glass and pottery. Both of these materials are man made plastics    and both were invented thousands of years ago. The people of the New Stone Age learned to make pottery before the dawn of recorded history. They modeled pots from moist clay and baked them hard in their fires. Every different tribe made this discovery, ages before they invented writing. Glass is much harder to make, so its discovery came later. Most likely several different people learned the trick by accident. But once again, the early records are lost in the dim past.

Glass, like pottery, is made by cooking simple minerals from the earth’s crust. The main ingredient is silica, the plentiful mineral used to make sand and a multitude of beautiful quartz stones. However, quartz is the hardest of common minerals. Tremendous heat is needed to fuse and remodel it to form glass. But this melting job requires less heat when soda is mixed with the quartz. And soda is present in certain pale, soft rocks called natrolites. Now let your mind roam back, back to the dawn of history. Picture people building a hearth or a campfire, perhaps on a beach. There is plenty of quartz in that beach sand, but the fire of wood logs is not hot enough to fuse into glass.

Now imagine a happy accident. There are natron stones on the beach and the people use them to build a hearth under their log fire. In the heat, the soft hearth stones boil and bubble. The soda in the natron mineral mixes with the quartz in the sand. The two ingredients fuse and form a clear, tacky material. When the fire dies down, there are gobs of wondrous glass in the ashes. This happy accident was described by a Roman writer, about 2,000 years ago. But it must have happened, perhaps many times, long before this. At least 3,500 years ago, the craftsmen of Egypt had already mastered the art of fine glass making. Their lovely glass goblets were found in the tombs of their kings. Even then, glass making was not new. Glass¬coated beads were unearthed in Mesopotamia, to the north of Egypt. They prove that people there had learned how to make glass at least 4,500 years ago.

Glass made from quartz and soda dissolves in water. But it is hard and durable when lime is added to the brew. This discovery also was made in the forgotten past. Early glass makers used quartz sand, soda and lime. Through the ages, the recipes improved by trial and error. Nowadays, we have thousands of recipes for different kinds of glass. But the basic ingredients are still sand, soda and lime.