Today, there is hardly any field of life in which glass is not used in one form or the other. Glass sheets are used in windows of houses, trains, motors cars, ships, and airplanes. The list of its products is, in fact, endless and includes water tumblers, decoration articles, and various kinds of bottles, sunglasses, spectacles, flasks, laboratory items, light bulbs, fluorescent tubes and a large number of other items used in our daily life. Do you know how this useful material is made?
The art of making glass is very old. A blue glass rod made in 2,600 B.C. And found in Babylonia. It is clear from these findings that man knew the art of making glass sometime around 2,600 B.C.
Sand (silica), soda (sodium carbonate) and lime (calcium carbonate) are the main constitutions used in the manufacture of glass. These materials are finely ground, mixed together and melted in a big furnace. When the mixture, after melting becomes homogeneous, it is molded in the shape of sheet or rods. The solid material so formed is glass. There are many kinds of glass. To make different kinds of glass, some other materials are added to the aforesaid mixture before melting it. In general, magnesium oxide, zinc oxide, lead oxides are the main additives used in the glass manufacturing industry.
For making colored glasses, oxides of copper, iron, selenium, chromium, cobalt etc. are used. The cobalt salt is mixed to make blue glass. Chromium or copper compounds impart green color whereas selenium salts make red glass.
Now fibers of glass are also used being produced. These are being used research work. Today scientists have developed a kind of glass which changes its color when illuminated by light. A special kind of glass is now in use for making bricks for building a house. By mixing some special materials in the glass before melting, transparent substances as strong as steel, have been developed. Sheets of this special glass are being used in space ships. Glasses conducting electricity are made by fusing a metallic oxide coating to the surface of borosilicate glasses. These kinds of glasses are used in panels for industrial and house heating.
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