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Over the last few centuries, man has created many
incredible inventions and made amazing discoveries. Some
of them are the automobile, the computer, dynamite,
electricity, the telescope and paper. Due to all these
inventions, man has been able to lead a very easy and
comfortable life. Glass is also one of the greatest
inventions of man. It is one of the most useful
materials man has made. The Egyptians were said to be
the first to use glass. They used it in a liquid form to
glaze their ornaments. Later, they discovered that a
blob of molten glass on the end of a metal pipe could be
blown in various shapes. If a person spun the pipe while
blowing the bubble of glass, it could be shaped into a
wine glass, a vase or a decanter.
What does glass consist of ? Unlike most solid
substances, it is not made up of crystals. In fact, it
is a liquid that has become rigid and hard. However, it
still has the chemical structure of a liquid.
Sand, soda and lime are needed to make glass. in a
glass factory, machines feed these ingredients into one
end of a huge tank while the molten glass comes out at
the other end. The ingredients are heated until they
melt and are almost white hot. Glass makers may keep the
glass molten for several days to get rid of the bubbles
of gas that form in it.
Molten glass is processed in various ways to make
glass objects. It may be drawn out between heavy rollers
to make sheet glass, or it may be poured onto flat steel
tables to make plate glass. Machines are used to press
small lumps of glass in moulds to make things like
tumblers and dishes or they may blow lumps into other
moulds to make bottles and electric light bulbs.
Today, manufacturers can make glass in fiber form
that can be woven with cloth. It is known as fiberglass.
The glass is drawn into a fine thread and woven with
cloth. When combined with special resins, fiberglass
makes a plastic-like material which is fast replacing
wood and metal because fiberglass is not only strong and
durable but lighter as well.
These are special kinds of glass for all sorts of
purpose, from the windows of aircraft to the lenses of
microscopes. There is also bulletproof glass, a type of
glass that is so tough that a bullet will not shatter
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1. |
(a) What is the advantage of
the use of inventions such as the automobile, the computer, dynamite,
electricity, telescope and paper ?
(b) Explain the meaning of
the word 'amazing'.
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