https___en.wikipedia.org_wiki_Johann_Heinrich_Schulze.xml
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Йохан Хайнрих Шулц Йохан Хайнрих Шулц (на немски: Johann Heinrich Schulze) e немски професор, най-известен с откритието, че някои соли на среброто, най-вече сребърен хлорид и сребърен нитрат, потъмняват в присъствието на светлина, както и за използването на тези ефекти да улови временни фотографски изображения. В експеримент, проведен през 1724 г. той установява, че смес от сребро и тебешир отразява по-малко светлина, отколкото чисто сребро. Въпреки че откритието му не осигурява условия за запазване на изображението, то дава основата за по-нататъшна работа, която довежда до създаването на фотографията.
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Johann Heinrich Schulze Johann Heinrich Schulze (12 May 1687 – 10 October 1744) was a German professor and polymath from Colbitz in the Duchy of Magdeburg. History[edit] Schulze studied medicine, chemistry, philosophy and theology and became a professor in Altdorf and Halle for anatomy and several other subjects. Notable discoveries[edit] Schulze is best known for his discovery that the darkening in sunlight of various substances mixed with silver nitrate is due to the light, not the heat as other experimenters believed, and for using the phenomenon to temporarily capture shadows.[1] Schulze's experiments with silver nitrate were undertaken in about 1717.[2] He found that a slurry of chalk and nitric acid into which some silver had been dissolved was darkened by sunlight, but not by exposure to the heat from a fire. To provide an interesting demonstration of its darkening by light, he applied stencils of words to a bottle filled with the mixture and put it in direct sunlight, which produced copies of the text in dark characters on the surface of the contents. The impressions persisted until they were erased by shaking the bottle or until overall exposure to light obliterated them. Because they were produced by the action of light, an extremely broad and literal definition of what a photograph is may allow even these fluid, ephemeral sun printings to qualify, and on that basis many German sources credit Schulze as the inventor of photography.[3][4] Though Schulze's work did not provide a means of permanently preserving an image, it did provide a foundation for later efforts toward that end. Thomas Wedgwood and Humphry Davy produced more substantial but still impermanent shadow images on coated paper and leather around the year 1800. Nicéphore Niépce succeeded in photographing camera images on paper coated with silver chloride in 1816 but he, too, could not make his results light-fast.[5] The first permanent camera photograph of this type was made in 1835 by Henry Fox Talbot.[1] Works[edit] - Abhandlung von der Stein-Chur durch innerliche Artzeneyen überhaupt und insonderheit von der neulich bekannt gewordenen Englischen . Franckfurt, 1740 Digital edition by the University and State Library Düsseldorf - Chemische Versuche . Waysenhaus, Halle 1745 Digital edition by the University and State Library Düsseldorf See also[edit] References[edit] - ^ a b Leslie Stroebel and Richard D. Zakia (1993). The Focal encyclopedia of photography (3rd ed.). Focal Press. - ^ This date is commonly misreported as 1725 or 1727, an error deriving from the belief that a 1727 publication of Schulze's account of experiments he says he undertook about two years earlier is the original source. In fact, it is a reprint of a 1719 publication and the date of the experiments is therefore circa 1717. The dated contents page of the true original can be seen here (retrieved 2015-02-21) - ^ Susan Watt (2003). Silver. Marshall Cavendish. Retrieved 28 July 2013. But the first person to use this property to produce a photographic image was German physicist Johann Heinrich Schulze. In 1727, Schulze made a paste of silver nitrate and chalk, placed the mixture in a glass bottle, and wrapped the bottle in ... - ^ Litchfield, Richard Buckley (1903). Tom Wedgwood, the First Photographer, etc., London, Duckworth and Co. Out of copyright and available free at archive.org. In Appendix A (pp. 217-227), Litchfield evaluates assertions that Schulze's experiments should be called photography and includes a complete English translation (from the original Latin) of Schulze's 1719 account of them as reprinted in 1727. - ^ Niépce House Museum: Invention of Photography: 1816-1818, Niépce's first tries (retrieved 2012-11-01)