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.
Manufactured in a similar manner to other kinds of glass, but possesses a very high refractive and dispersive power.
So called because it originated in Jena, Prussia. It is especially valuable for the manufacture of high-class lenses, on account of the quality of the various ingredients employed in its manufacture, which render almost any desired degree of refraction or dispersion.
Made of both flint and crown glass, and lenses constructed of both kinds and placed together overcome chromatic aberration.
Manufactured by an entirely different process from either crown or flint glass and is especially adapted for use in large windows on account of its strength and toughness.
C2H5NO2 - II, 524. Glycocoll. A light, lustrous powder. Soluble in water providing the water has been made alkaline. Uses. It is a powerful but slow acting developer. Gives clear images of a grayish-black color. Especially valuable for copying and photomechanical work.
A yellowish-brown metal. Toning prints with gold consists of depositing a thin layer of metallic gold on the surface of the print. Gold is used in photography only in conjunction with other chemicals.
AuCl3 + HC1 + 4H2O - IV, 51. Gold Trichloride. Yellow crystals. Obtained by dissolving gold in aqua regia (See Aqua Regia). Usually sold in tubes containing 15 grains and is dissolved in 15 drams of water so that each dram of solution contains I grain of gold chloride. Used extensively for toning of silver papers.