earliest fleeting letter photograms (circa 1717) Around 1717, German polymath Johann Heinrich Schulze accidentally discovered that a slurry of chalk and nitric acid into which some silver particles had been dissolved was darkened by sunlight. After experiments with threads that had created lines on the bottled substance after he placed it in direct sunlight for a while, he applied stencils of words to the bottle. The stencils produced copies of the text in dark red, almost violet characters on the surface of the otherwise whitish contents. The impressions persisted until they were erased by shaking the bottle or until overall exposure to light obliterated them. Schulze named the substance "Scotophors" when he published his findings in 1719. He thought the discovery could be applied to detect whether metals or minerals contained any silver and hoped that further experimentation by others would lead to some other useful results. Schulze's process resembled later photogram techniques and is sometimes regarded as the very first form of photography. De la Roche's fictional image capturing process (1760) The early science fiction novel Giphantie (1760) by the Frenchman Tiphaigne de la Roche described something quite similar to (color) photography, a process that fixes fleeting images formed by rays of light: "They coat a piece of canvas with this material, and place it in front of the object to capture. The first effect of this cloth is similar to that of a mirror, but by means of its viscous nature the prepared canvas, as is not the case with the mirror, retains a facsimile of the image. The mirror represents images faithfully, but retains none; our canvas reflects them no less faithfully, but retains them all. This impression of the image is instantaneous. The canvas is then removed and deposited in a dark place. An hour later the impression is dry, and you have a picture the more precious in that no art can imitate its truthfulness." De la Roche thus imagined a process that made use of a special substance in combination with the qualities of a mirror, rather than the camera obscura. The dark place in which the pictures dried suggests that he thought about the light sensitivity of the material, but he attributed the effect to its viscous nature. Scheele's forgotten chemical fixer (1777) In 1777, the chemist Carl Wilhelm Scheele was studying the more intrinsically light-sensitive silver chloride and determined that light darkened