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Mosquée du Sultan Achmet Robertson, James  (British, 1813-1888)

Henri-Edmond Robiquet (1822-1860) was a French physicist and a member of the Société de Pharmacie. He mastered photography and much of the photographic science in his textbook was personally tested in his lab at the school. This work contains a photograph using the carbon powder print techniques of Garnier and Salmon. In 1858, Henri Garnier and Alphonse Salmon discovered the photochemical reaction of ferric citrate, altering its hygroscopic and solubility properties. This led to the invention of their "dusting-on" process procédé au charbon using a positive rather than a negative to make the exposure. A year later, Garnier and Salmon abandoned iron salts to pursue emulsions of ammonium dichromate and sugar. The plate in Robiquet’s book is one of few, or maybe the sole, published example from their workshop of their carbon powder method.