The albumen printing process gave photographers better reproduction of detail, a wider tonal range, and greater print stability than the salted paper process that preceded it. It remained the photographic process of choice throughout the second half of the nineteenth century. Albumen printing and salt printing both use the energy of light waves, rather than chemical reactions, to create an image. With albumen printing, however, the image resides in the layer of albumen on the paper’s surface, not in the paper itself. The albumen process for photographic prints was invented in 1850 by Louis Désiré Blanquart-Evrard (1802–1872). On May 27, 1850, he presented his method to the French Académie des Sciences and then published it in the scientific journal Compte rendus des séances de l’Academie des Sciences (1850). The process begins with the application of albumen, a solution of egg whites and sodium chloride, to the surface of very thin paper. (This thin paper is an identifying characteristic of albumen prints, which are typically mounted to board or card stock.) The egg-white coating produces a semigloss finish. After drying, the paper is then made light sensitive by the application of a silver nitrate solution, which combines with the sodium chloride on the paper to produce light-sensitive silver chloride. The image is developed via contact printing, or pressing a negative or object directly to the paper surface and exposing it to light—historically, diffused sunlight rather than artificial light. After exposure, the paper is submerged in running water to remove excess silver. The process produces a purple to brown image. The photographer can change the color by applying a toner, such as a gold compound. This extra step can also aid in image permanence. Albumen prints require a fixer, such as sodium thiosulfate, to keep the image from fading. A final wash is needed to rid the paper of extraneous chemicals.