Johann Heinrich Schulze

Johann Schulze was a German physician and anatomy professor who made a significant discovery in the development of photography when he observed that silver salts darkened when exposed to sunlight. In 1725, while attempting to create a phosphorescent material by combining a slurry of chalk with nitric acid containing dissolved silver, he noticed that sunlight, and not heat, turned the substance black. He applied stencils of words to bottles filled with the mixture and put them in direct sunlight. This produced copies of the text in dark characters on the surface. The impressions persisted until they were erased by shaking the bottle or until an overall exposure to light obliterated them.

Schulze never created a permanent image but, because his images were produced by the action of light, a broad and literal definition of what a photograph is, he is a member of the Silver Hall of Fame. Many German sources credit Schulze as the inventor of photography.