Did you know that most 1800s photographs are made out of eggs? Photographic prints require a clear substance to both hold the photochemicals to the paper and allow the chemicals to react, or develop, under sunlight. 1800s photographers found that albumen, or egg whites, worked best. Photo paper manufacturers often had chicken farms on site to supply the eggs. . . . The standard 1800s paper photograph is called the albumen photograph.
A later invention named gelatin worked better than albumen, and most 1900s black and white photographs are called gelatin-silver photos.