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:
“Novels so often provide an anodyne and not an antidote, glide one into torpid slumbers instead of rousing one with a burning brand.”
—Virginia Woolf (1882–1941)
“The awaited scream rises,
the shattering
of glass and the cracking
of bone
a polar tumult as when
black ice booms....”
—Denise Levertov (b. 1923)