The albumen silver print, invented in 1850, was the most popular photographic printing process of the 19th century. To make albumen silver prints, a sheet of paper is coated with albumen (egg white) and salts, then sensitized with a solution of silver nitrate. The paper is exposed in contact with a negative and printed out, which means that the image is created solely by the action of light on the sensitized paper without any chemical development. Because the paper is coated with albumen, the silver image is suspended on the surface of the paper rather than absorbed into the paper fibers. The result is a sharp image with fine detail on a smooth, glossy surface.
Video from the George Eastman Museum