camera obscura - A device initially used by artists to draw. It consisted of a box with a small hole or lens at one end, and a translucent screen on the other. The inverted image of what the hole faced would appear enlarged on the screen, where an artist could then trace the image that was transmitted. This device would become the basis for camera lenses later on.
calotype - Greek for "beautiful picture", it was a photographic process based on negatives, and was invented by W. H. Fox Talbot. The image was produced on paper treated with silver iodide and developed by sodium thiosulphite.
collodion - A colourless or yellow syrupy liquid that consists of a solution of pyroxylin in ether and alcohol.The collodion process involves preparing negatives by coating a glass plate with collodion containing iodide, exposing in a camera while still wet, and then developing with pyrogallol or acidified ferrous sulfate, and fixing in a cyanide solution.
daguerreotype - A type of photography, in which the image was produced on iodine-sensitized silver and developed in mercury vapor. The background became black, and the subject was seen in gradations of gray.
dry plate - A glass plate coated with an emulsion consisting of silver bromide and silver iodide in gelatin. It could be stored for long periods of time before exposure, unlike the wet plate.
emulsion - A substance that is sensitive to light and consists of one or more of the silver halides suspended in gelatin. It is typically applied in a thin layer to one surface of a film; In chemistry, a colloid in which both phases are liquids.
kodachrome - A type of multi-layered color film.
negative - A complete inversion of a positive image (or final print), in which light areas appear dark and vice versa. In regards to color photography, the negatives are additionally color reversed. For example, greens appears magenta and blues appear yellow. Especially important to development of photography, because can make multiple positive prints from a single negative.