glassy edge of a grass—blade? It is just possible that the straw itself furnished all the materials for the lumps of glass. All that was needed was a hot enough fire to melt them together.
The finding of glass where straw had been burned, set those wide-awake Egyptians to thinking and experimenting. They learned to mix sand with ashes, melt them together, and mould, roll and blow glass into various shapes when it was soft and hot. Our word "soda," is the name the early Italian glass makers gave to ashes. "Soda" really means solid. Today, by soda, we mean an alkali. But soda still has that old meaning of soldering or solidifying. It was the soda that fused the sand into a solid mass.
If one of your window panes could tell the story of its birth in a fiery furnace it would say something like this: "I have some of the same things in me as you have. Two of them are silica and lime. You have silica in your glossy (glassy) hair, and lime in your bones. Pure white sand is nearly all silica. And I was made with heat. You couldn’t live unless you were made warm either. I needed more heat than you, that’s all. You use sunshine. I used dead and gone sunshine—coal. As the plant is made up of little cells that the sun acts upon, so every grain of sand in me was acted upon by the fire.
"The heat made the little silica cells in the sand fly apart, and it separated all the other things that are in the sand from them. Then the silica particles flowed together again. ‘Birds of a feather flock together,’ you know. Iron particles flock together when the iron ore is melted. So do gold and silver and silica, or glass. The particles in the sand that are not glass go off by themselves. Where do you suppose they go?
"They just evaporate or disappear in gas. They are attacked by the soda. Soda, lye, potash, or some other alkali does something of the same sort to fats and oils in making soap. It breaks up the fat and eats particles that are not soap. Lime is the purifier, making impurities float to the top. You purify your house with lime. Heat helps, too, as it helps soda and sour milk make a gas to raise mama’s biscuits in the oven."
Clean, white sand, soda and lime are put into enormous pots of fireclay in very hot furnaces. Some broken glass is added. For seed? Perhaps. It may be that the bits of glass, having been through the process before, are able to show the way to the raw materials. In making the big clay pots pieces of old pots are mixed with the
