Toronto. Niepce was a lithographer with a poor skill in drawing. To overcome this impediment, he tried various means to capture an image on a metal plate. He had initially tried paper and a silver-chloride solution a la Wedgwood, but he too could not keep the paper from going black.
His fresh egg was a solution of bitumen of Judea (asphalt) and solvent to make a varnish coating on a metal plate.The varnish was light sensitive. After a long exposure to sunlight hardened the varnish not shaded, a wash of petroleum and lavender oil removed the softer unexposed parts leaving a negative representation of the subject on the metal plate.
The first successful heliograph image was announced in 1822 and later commemorated in his home town of Saint-Loup-de-Varennes with a stone monument. The earliest photograph or heliograph created in a camera obscura was a scene of his back yard taken in 1826/7 from an upstairs window in his house. The plate is now in the Gernsheim collection at the University of Texas.
Sadly, his process was faint, contrasty, and extremely slow (hours in bright sunlight). He later collaborated with another Frenchman to make the process practical but died before success was achieved.