viscosity, having no definite melting point obtained by fusing a mixture of a number of metallic
silicates or borates of Sodium, Potassium, Calcium, and Lead.
Manufactured Glass dates from pre-historic times in the Far East, India and Egypt
Little is known about the first attempts to make glass.
However, it is generally believed that glass making was discovered 4,000 years ago, or more, in Mesopotamia.
The Roman historian Pliny attributed the origin of glassmaking to Phoenician sailors.
He recounted how they landed on a beach near Ptolemais (in modern-day Israel), propped a
cooking pot on some blocks of natron (a naturally-occurring alkali substance) they were
carrying as cargo, and made a fire over which to cook a meal.
Properties of glass :
1. It absorbs, refracts or transmits light.
2. It can take up a high polish and may be used as a substitute for very costly gems.
3. Is has no definite crystalline structure.
4. It has no sharp melting point.
5. It is affected by alkalis.
6. It is an excellent electrical insulator at elevated temperatures due to the fact that glass can be
considered as an ionic liquid. The ions are not easily moved at room temperature because of the
7. It has good workability. It can be blown, drawn or presses. But it is difficult to cast in large
8. It is extremely brittle.
9. It is not affected by air or water.
10. It is not easily attacked by ordinary chemical reagents.