| Price Rupert's drops are produced by melting small amounts
of glass from the end of a rod, and letting the resulting teardrop- shaped
blobs of glass fall into a vat of water. In the process of rapid quenching,
tremendous internal strains are set up. Breaking the end from a drop will
cause it to shatter into tiny pieces. Beware: this is a dangerous demonstration!
The stress patterns in glass can be observed by placing
the glass between crossed polarizing filters. The drops at the right, from
the United States Military Academy at West Point, have been glued to a
thin sheet of glass for use in a projector.
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