Albumen prints are a variety of photographic paper print in which a finely divided silver and gold image is dispersed in a matrix of egg white. Such prints constitute by far the largest category of objects in 19th century photographic collections. Albumen paper became the most widely used photographic printing material about 1855, and remained so until 1895; it did not disappear completely from photographic practice until the 1920's.
The span of time during which albumen paper predominated in photographic usage represents not only an important formative period in photographic aesthetics and technology, It is also the era during which photography first began to be Integrated into a wide range of human activities, thus becoming an influence on the culture at large. This occurred in ways which we are only now beginning to appreciate. One ongoing example is our changing evaluation of the photographs of the American West and American Indian peoples; these images shaped attitudes toward the West at the time they were made--and still do--only now their power is magnified because for us, they embody both artistic achievement and deep historical significance.
(Source: Albumen.conservation.org: http://albumen.conservation-us.org/library/c20/reilly1980.html)
See also Making a Positive: Albumen Print