French crystallographer and chemist who contributed to the early chemistry of photography by introducing potassium cyanide as a fixing agent which reacted with the silver salts on the light-sensitive plate surface to form soluble silver cyanide which could be washed away water. He published his method in La Lumière on 23 Apr 1853. The following year, in the same journal he published what are regarded as the first experiments with collodion dry plates on 22 Apr and 27 May 1854. In 1873, he grew the first synthetic ruby crystal.