This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
The relation of the diameter of the aperture of the lens to its focal length. The focal length divided by the diameter of the stop equals the intensity ratio.
(See Image, Latent.)
(See Ammonium Iodide.)
(See Cadmium Iodide.)
(See Potassium Iodide.)
(See Silver Iodide.)
Bluish-black friable plates; metallic luster; peculiar odor; sharp acrid taste. Soluble in a solution of potassium iodide; carbon disulphide; chloroform. Use: Vapor of iodine was employed as a sensitizer by Daguerre for his silver plates. In combination with other compounds iodine is used in sensitive emulsions.
Made by dissolving iodine in alcohol. Used to remove stains of silver nitrate, first touching the stains with tincture of iodine and then with potassium cyanide or hypo.
A metal of a grayish, luster-like color. Use: Various salts of iron are used in photography, especially in the iron printing processes, such as blue-print process (ferro-prussiate), the platinum process, etc. The word ferrous or ferric is often used in place of the word iron. The ferrous salts contain more oxygen than the ferric.
(See Ferric Ammonium Citrate.)
(See Ferric Chloride.)
(See Ferric Nitrate.)
(See Ferrous Oxalate.)
(See Ferric Chloride.)
(See Ferrous Sulphate.)
A term applied to sensitive emulsions which are prepared to render correctly relative color values. (See Orthochromatic.)
An asphaltum varnish
(See Eau de Javelle.)
(See Glass, Jena.)
A printing process quite popular, especially among amateur photographers. Similar in principle to platinum printing process. The action of light changes the ferric oxalate to ferrous oxalate and the latter salt when in solution reduces the silver nitrate to metallic silver, resulting in bluish-black or black images.
A metric measure of weight
A trade name used by the Eastman Kodak Company and applied to both the box and folding cameras made by that concern.
A varnish composed chiefly of shellac dissolved in alcohol, colored with dragon's blood, gamboge, etc.
There are various forms of lamps used in photography for dark-room illumination. In all cases, however, it is essential that the light, in order to be perfectly safe for handling sensitive plates, consist of a deep ruby as well as an orange glass or similar material, either paper or cloth, which will give identical results.