If teacher says flatly that fresh water always freezes at 32° F. under normal atmospheric pressure, she is wrong. Before it can turn to ice, water needs nucleiminute particles, usually of some other substance, e.g., dust. Last week, General Electric Research Laboratory announced that its scientists had succeeded in supercooling water to 39° below zero71° lower than its normal freezing point. At that temperature, nuclei seemed to form spontaneously and the supercooled water finally became ice.
Metals act the same way. Mercury thermometers are of little use in Arctic winters because they freeze at 37.7° below zero. G.E. researchers kept mercury, free...
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