Ferrotype

Ferrotype, a photographic process used for the formation of a positive picture without the previous formation of a negative. [Photography.] The process is carried out in the following manner: A thin sheet of blackened iron is coated with an even layer of "iodised" collodion - i.e. collodion containing some iodide and bromide of silver in solution. It is then immersed in a solution of silver nitrate, and is ready for exposure in the camera. The image is usually developed by a solution of ferrous sulphate, and in those parts where the light has acted a deposit of silver of a white or grey colour is produced. The shadows are represented by the black iron showing through the collodion. The plate is fixed by a solution of potassium cyanide, which dissolves away the unaltered silver salts. The process is one very largely used by itinerant and sea-beach photographers, as the photographs, though not usually of high artistic merit, can be taken, developed, dried, and completed in a few minutes.