1816-1818 > NIEPCE'S FIRST TRIES • 1819-1824 1825-1829

> Towards Photography invention

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 .

Replica of a camera obscura

"Rétine au chlorure d'argent" (Retinas, reconstitution)

> 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“ .

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Obtention of direct positives

Seeking to obtain positive images , Niépce turned towards compounds that light bleaches instead of blackening . He then tried with salts and iron oxide and also manganese black oxide . Even though he got some results, he stumbled over the fixing problem when it is necessary to eliminate the initial chemical that has not been transformed by light .

> The latent image concept

To solve this problem , he tried to find a method that would lead to obtain etched images on a base and studied the effects of light on acids hoping to observe their decomposition. Then one could spread on a calcareous stone some acid whose strength varying with light intensity
more or less would etch the stone, according to the projected image hues. But unhappily acids are not decomposed by light and this is another failure .
Niépce, however , through his last research , understood that it is not necessary to use a coumpound whose photochemical 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 . Consequently he is interested by all the subtances that interact with light .

> Parallel research

Niépce stops his studies on light for almost a year . Answering to a competion started in France he tries to find deposits of calcareous stone for lithography .(lime stone).
September 1816 : the two brothers, communicating by mail , try a new fuel for their engine . Using kerosene , they discover the fuel injection principle as we know it in today’s engines.

> Principle of the invention of photography

In march 1817 , an obstinate Niépce restarted his research on making images . 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 but what made it especially interesting to Nicephore is that it loses its solubility in alcohol . He understood that because of this property one could find the difference between the modified resin and the intact on , therefore fixing the image .
At first he got pretty good results experimenting directly with sun-light , but he 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 . At the same time in
1818 he 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 “