---
title: "History of photography"
chunk: 2/7
source: "https://en.wikipedia.org/wiki/History_of_photography"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:00:07.060798+00:00"
instance: "kb-cron"
---

=== Before 1700: Light-sensitive materials ===
The notion that light can affect various substances—for instance, the sun tanning of skin or fading of textile—must have been around since very early times. Ideas of fixing the images seen in mirrors or other ways of creating images automatically may also have been in people's minds long before anything like photography was developed. However, there seem to be no historical records of any ideas even remotely resembling photography before 1700, despite early knowledge of light-sensitive materials and the camera obscura.
In 1614 Angelo Sala noted that sunlight will turn powdered silver nitrate black, and that paper wrapped around silver nitrate for a year will turn black.
Wilhelm Homberg described how light darkened some chemicals in 1694.

== 1700 to 1802: earliest concepts and fleeting photogram results ==

=== Schulze's Scotophors: 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 it by disintegrating it into microscopic dark particles of metallic silver. Of greater potential usefulness, Scheele found that ammonia dissolved the silver chloride, but not the dark particles. This discovery could have been used to stabilize or "fix" a camera image captured with silver chloride, but was not picked up by the earliest photography experimenters.
Scheele also noted that red light did not have much effect on silver chloride, a phenomenon that would later be applied in photographic darkrooms as a method of seeing black-and-white prints without harming their development.
Although Thomas Wedgwood felt inspired by Scheele's writings in general, he must have missed or forgotten these experiments; he found no method to fix the photogram and shadow images he managed to capture around 1800 (see below).

=== Elizabeth Fulhame and the effect of light on "Silver Salts" (1794) ===
Elizabeth Fulhame's book An essay on combustion described her experiments of the effects of light on silver salts. She is better known for her discovery of what is now called catalysis, but Larry J. Schaaf in his history of photography considered her work on silver chemistry to represent a major step in the development of photography.