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:
“If I were a Brazilian without land or money or the means to feed my children, I would be burning the rain forest too.”
—Sting [Gordon Matthew Sumner] (b. 1951)
“Like a wild stranger out of wizard-land
He dwelt a little with us, and withdrew;
Black and unblossomed were the ways he knew,
Dark was the glass through which his fire eye shined.”
—Edwin Arlington Robinson (1869–1935)