1816-1818 — Niépce’s first Experiments
Towards the Invention of Photography
In 1816, a year before the pyreolophore patent runs out, Claude goes to Paris, then to England in 1817, trying to make work the engine invention.
Nicephore starts by himself new research on an idea that has obsessed him for many years : making permanent on a support through a compound the images seen at the back of camerae obscurae.
Until then , these boxes with a lens adapted on a hole , projecting on the back an inverted image of the outside view , had only been used as a drawing aid.
The first world negative (non fixed)
For his first experiments , Nicéphore Niépce positioned at the back of a camera obscura sheets of silver salts coated paper, known to blacken with daylight . In may 1816 he produced the first image of nature : a view from a window . It was a negative and the image vanished because in broad daylight the coated paper becomes completely black . He calls these images “retinas”.
Obtention of Direct Positives
Seeking to obtain positive images, Niépce turned towards compounds that are bleached by light instead of blackened. He then tried with salts and iron oxide, as well as manganese black oxide. Even though he got some results, he stumbled over the fixing problem, which arises when he tried eliminate the initial chemical that had not been transformed by light yet.
The Latent Image Concept
To solve this problem, Niépce tried to find a method that would make him obtain images etched on a base. To do this, he researched the effects of light on acids in the hope to observe their decomposition. Based on these results, he thought he could simply spread acids on calcareous stones, whose strength would vary with light intensity and etch the stone more or less, according to the hues of the image projected. However, acids are not decomposed by light, so this attempt was yet another failure.
Nevertheless, it allowed Niépce to understand that it is not necessary to use a coumpound whose photo-chemical transformation is visible to the naked eye, and that even an invisible change of chemical properties under light action may induce the appearance of an image during a reaction, either with the base or another compound. As a consequence, Niépce got interested by all substances that interact with light.
Parallel research
Niépce stopped his studies on light for almost a year. Following a competion started in France, he tried to find deposits of calcareous stones for lithography (limestone).
In September 1816, the two Niépce brothers, communicating by mail, tried out a new fuel for their engine. Using kerosene, they discovered the fuel injection principle, as we know it in today’s engines.
Principle of the invention of photography
In March 1817, Niépce decidedly took up his research on making images again. While reading chemistry treatises, he focused his attention on the resin of Gaïacum extracted from a coniferous tree. This yellow resin becomes green when exposed to day-light. What made it particularly interesting is that it loses its solubility in alcohol. Niépce understood that thanks to this property it was easy to see the difference between the modified and the intact resin, thus fix the image.
At first he got rather good results experimenting directly with sun-light, but failed when using a camera obscura. He did not know that only U-V rays were active on this resin and that they were filtered by his camera obscura lens. In 1818, next to fixing images, he also developed a keen interest for the dandy horse (ancestor of the bicycle without pedals) and got a lot of attention riding the roads of Saint-Loup-de-Varennes on his “velocipede”.
