Niépce's heliography process was groundbreaking but far from perfect. To make the image, Niépce coated a pewter plate with bitumen of Judea, a natural asphalt that hardens when exposed to light. After placing the plate in a camera obscura (basically an ancient version of the camera), Niépce let sunlight pass through, which slowly hardened the bitumen where the light hit. The parts of the plate that remained soft were washed away, leaving behind the image. But because of the long exposure times and the materials involved, the process was far from practical for everyday use. However, Niépce’s work laid the foundation for future innovations in photography.
Here's a video of a guy trying out the process himself.
https://youtu.be/KVcqYsvlpUE?feature=shared 