Ever since the invention by Alhazen (965-1040) of the pinhole camera, which projected an image onto a surface, people sought a way of "fixing," and thus recording, that image. By accident, in 1727, the German chemist Johann Schuize discovered that a mixture of chalk, nitric acid, and silver darkened when exposed to sunlight, and the rate of darkening increased if more silver was added. By 1777 the Swedish chemist Carl Scheele had been able to fix, or make permanent, the results of this change using ammonia.
Joseph Nicephore Niepce (1765-1833) produced the first permanent photographic image in 1826. He first used a flat pewter plate covered with bitumen, but then quickly moved on to silver compounds. Louis Daguerre produced silvered images that were very delicate and could not be copied. Although the exposure time was about ten minutes, he managed to produce daguerreotypes of famous people such as Abraham Lincoln
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