Box with cartes de visite of members of the Regout family; Netherlands; c. 1865. Photograph: Kleon3 (2019), Wikimedia Commons

Photographic printing paper that is coated with albumen, or egg white, and salt before being dipped in a silver nitrate solution to make it light-sensitive. Developed by Louis Désiré Blanquart-Evrard around 1850, the albumen print was the most extensively used photographic printing method in the late nineteenth century. It was used for the small-format photographs known as carte de visite whose popularity in Europe helped establish the wide prevalence of photography.