Kim Werner, age 109 of Lancasterg Pa.9 for her question:
HOW DO WE GET GLASS?
Glass can be either a man made product or one from nature. It is certainly one of our most useful materials as we find it playing important roles in many of our activities.
We find glass in our homes in such thins as light bulbsp table service and food containers. And could you imagine a home without windows?
Volcanoes made a natural glass called obsidian long before man discovered how to manufacture it. The man made product was probably discovered about 5000 B.C. by Phoenecian sailors who used blocks of soda to hold their cooking Pots. The heat from the fire melted the sodas and sand that was on the ground combined to Produce glass.
Glass is made largely of silicate limestone and soda ash. Today there are more than 50,000 kinds of glass made for different purposes.
Ordinarily you think of glass as very fragilet and much of it is. But there are also types that can stop bullets.
A common formula for soda lime glass is 72 percent white sand, 15 percent sodaf 9 percent limes 3 1/2 percent aluminum o ide and about 1/2 percent of boric acid. This type of glass will melt at 19350 degrees Fahrenheit, which is a relatively low temperature.
The Egyptians in the 16th century B.C. were known to have the glass making secret, but it wasn't until the fourth century A.D. that glass blowing was invented. During the Roman Empire clear glass was madev and techniques for making decorative colored glass were also discovered by the Romans.
In the late 1200sp a guild of Venetian glass workers was formed. These craftsmen discovered the now famous Cristallo glass that was used in many elaborate forms.
As early as 1609 there was a glass making business in Jamestown in the American Colonies. Little progress was made since there was a lack of skilled craftsmen.
By the time of the American Revolution there were a number of glass making plantso most of them in eastern Pennsylvania. The material they Produced was very e pensive. It wasn't until the 1800s that the glass making industry really flourished.
Glass is nonporous and nonabsorptive and therefore is resistant to many thins, including acid. It is an excellent electrical insulator.
We can blow, roll, hand mold or cast glass. It can also be drawn to produce sheet glass and tubes. There are thousands of uses for the wonderful productq including spinning it into fiber for fireproof curtains.