If you have a photosensitive material, there's a chance you can capture an image on it. An English photography pioneer named Thomas Wedgwood covered different materials with silver nitrate. For example, he put the silver nitrate on pieces of leather and glass, stuff like that. Anyway, he then placed these materials inside the camera obscura and projected images onto them. What do you think the result of this was? Of course! He was able to create a photograph on the surface of the material. But there was a catch ... Wedgwood didn't have a way of preserving, or fixing, the image. So when the piece of leather or whatever was exposed to light later, the entire thing would turn dark, and the photo was lost. Obviously this was a problem ... and it was one that Joseph Nicephore Niepce was determined to overcome. He experimented with different types of photosensitive compounds and eventually found success with bitumen-coated paper. Bitumen is a sticky liquid that is found in petroleum, and like silver salts, it's photosensitive. So Niepce took this photosensitive paper and he put it in his camera obscura. After projecting an image on the paper for eight hours, he washed it in lavender oil in order to remove the unexposed bitumen. As a result, he fixed the image and created the first permanent photograph!