1. Glass can take these forms: fine like a spider web, heavy like a telescope lens, stronger than steel, or more fragile than paper.
3. Explained very simply, to make glass, use: a mixture of sand, soda, and lime cook and cool.
5. Early glassmaking was slow and costly for these reasons: furnaces were small, the heat produced was not enough to melt the materials, and glass blowing and pressing were unknown.
6. Merchants soon had a need for glass containers when they discovered that oils, honey, and other liquids; could be preserved better in glass.
7. There are many kinds of glass; each possesses a special quality.
8. Flat glass is used when very clear, precise vision is required it comes in the following classifications: sheet, plate, and float.
10. Flat glass, optical glass, and decorative glass; were used prior to this century however, many special types of glass have been invented since 1900.
13. Fiberglass, which is made of tiny; but solid rods of glass, has many uses.
14. The fiberglass industry fills the following needs: heat insulation, yarn and cloth, electrical insulation, firefighters' suits, and automobile bodies.
15. Raw materials used in making optical glass must be pure in order to make flawless lenses for eyeglasses, cameras, and telescopes; therefore, the production of optical glass is expensive.
16. The shaping of glass can be accomplished by these four methods: blowing, pressing, drawing, and casting.
17. In glass blowing, a worker uses a hollow iron blowpipe with one end dipped in molten glass; she or he blows gently into the pipe until the molten glass bulges out and forms a hollow tube.
18. This glass "bubble" can be formed into the desired shape by: squeezing, twirling, or stretching it.
