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.
CuSO4 + 5H2O - II.
Large, deep-blue crystals, slowly efflorescent in dry air; stringent, metallic, styptic taste. Soluble in 2.6 parts water. Used to bleach untoned prints or bromides when desired to sketch over with India ink for line reproduction; also, used in conjunction with other chemicals for toning bromide prints.
Term applied to making copies.
(See Mercuric Chloride.)
A plain glass used to protect the film side of a lantern-slide.
(See Lens, Covering Power.)
X. Cramer Plates - II, 551-641.
A large vacuum tube, spherical or pear-shaped, used in conjunction with a powerful induction coil to produce Rontgen, or X-rays.
(See Glass, Crown.)
An earthenware vessel made to withstand very high temperatures. Used for melting or fusing various metals and chemicals.
An inorganic substance which has assumed the form of a regular solid, commonly bounded by plane surfaces. Crystals of various substances may be formed by dissolving or by fusing, and allowing to cool gradually.
The process of becoming crystalized.
The formation of crystals on the surface of the negative due to improperly washing after fixing.
(See Copper Sulphate.)
An optical term used to denote the effect produced by a lens, the field of which is spherical in shape rather than plane. In other words, the focus of the central rays of light on a plane farther from the lens than that of the marginal rays.
Sheets of brass, celluloid or other material, having openings of various sizes and shapes for the trimming of prints by means of a small cutting wheel.
(See Plates, Cutting.)
(See Potassium Cyanide.)
(See Lens, Dagor.)
One of the first photographic processes. The picture is obtained on a highly polished silver plate. With this process a direct positive is obtained, the plate being sensitized by exposure to fumes of iodine in a dark box. After exposure in the camera, the latent image is developed by fumes of mercury and fixed by hypo and sulphite of soda. The process is named after the inventor, Daguerre, and was first successful in 1839.
(See Lens, Dallmeyer.)
Dammar. Yellowish-white, roundish, semi-transparent masses of varying degrees of hardness. Soluble in oil of turpentine, benzole or chloroform. Used in varnishes and retouching mediums.