A burning glass or burning lens is a large convex lens that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface. Burning mirrors achieve a similar effect by using reflecting surfaces to focus the light. They were used in 18th-century chemical studies for burning materials in closed glass vessels where the products of combustion could be trapped for analysis. The burning glass was a useful contrivance in the days before electrical ignition was easily achieved.
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Famous quotes containing the words burning and/or glass:
“Being innocent, he dreaded that he died
Hating his God, but what he was was plain:
An old kind man brave in his burning pride.”
—Dylan Thomas (1914–1953)
“Here in the centre stands the glass. Light
Is the lion that comes down to drink. There
And in that state, the glass is a pool.
Ruddy are his eyes and ruddy are his claws
When light comes down to wet his frothy jaws”
—Wallace Stevens (1879–1955)