What is Pyrex Glass?

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Pyrex is a type of glass which is designed to resist heat. It is made by replacing some of the silica (silicon dioxide) in normal glass with boron trioxide. It is also known by the name of borosilicate glass. Pyrex expands very little when it is heated and this prevents it from cracking. It has a higher melting point than normal glass and is resistant to many chemicals. This makes Pyrex containers suitable for use in laboratories and for ovenware in the house. Because it is resistant to contraction and expansion, Pyrex is also used in astronomical telescopes.

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