Johann Heinrich Schulze
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Johann Heinrich Schulze or Schultz (12 May 1687 – 10 October 1744) was a German professor and polymath from Colbitz in the Duchy of Magdeburg.
History
Schulze studied medicine, chemistry, philosophy and theology and became a professor in Altdorf and Halle for anatomy and several other subjects.
Notable discoveries
Schulze is best known for the discovery that certain silver salts, most notably silver chloride and silver nitrate, darken in the presence of light. In an experiment conducted in 1724 he determined that a mixture of silver and chalk reflects less light than untarnished silver. Though his discovery did not provide the means of preserving an image - the silver salts continued to darken unless protected from light - it did provide the foundation for further work in fixing images. The first permanent photograph was made in 1826 by Joseph Nicéphore Niépce in Paris, the first permanent photograph based on this principle was made shortly after by William Henry Fox Talbot. Other researchers in this field included Thomas Wedgwood and Sir Humphry Davy.
See also
