19th Century Photography
Photography is an early example of nanotechnology, which depends on the production of silver nanoparticles sensitive to light.
Photographic film is a thin layer of gelatin containing silver halides and a base of transparent cellulose acetate. The light decomposes the silver halides, producing nanoparticles of silver, which are the pixels of the photographic image. In the late eighteenth century, the British scientists Thomas Wedgewood and Sir Humphry Davy were able to produce images using silver nitrate and chloride, but their images were not permanent. The first successful photograph was produced in 1827 by Joseph Niépce using material that hardened on exposure to light. This picture required an exposure of eight hours. Niépce went into partnership with Louis Daguerre. Although Niépce died of a stroke only four years later, Daguerre continued to experiment, and, in 1839, discovered a way of developing photographic plates, a process which greatly reduced the exposure time from eight hours to half an hour. He also discovered that an image could be made permanent by immersing it in salt.