In some cases there is no way to tell, short of exacting scientific analysis, just what sort of variation was used to obtain a specific result. Most early photographs, however, fall into recognizable categories for which brief descriptions follow in alphabetical order.
Albumen prints outnumber any other type of photographic positive made during the nineteenth century.
They have a sepia color and slightly glossy surface. Thin sheets of paper were first coated with egg white and salt, then floated on silver nitrate to make them sensitive to light. The image is created by printing under a negative in sunlight. The finished picture is fixed, washed, and often gold toned before mounting. Invented by Louis Desire Blanquart-Evrard of France in 1850.