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:
“us burning plains,
Bristled with cities, us the sea received.”
—Matthew Arnold (1822–1888)
“Only one marriage I regret. I remember after I got that marriage license I went across from the license bureau to a bar for a drink. The bartender said, “What will you have, sir?” And I said, “A glass of hemlock.””
—Ernest Hemingway (1899–1961)