A Manual of Photographic Chemistry, Including the Practice of the Collodion Process; Including the Practice of the Collodion Process

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 11 CHAPTER II. THE SALTS OF SILVEE EMPLOYED IN PHOTOGBAPHY. By the term Salt of Silver we understand that the compound in question contains Silver, but not in its elementary form; the metal is in fact in a state of chemical union with other elements which disguise its physical properties, so that the Salt possesses none of the external characters of the Silver from which it was produced. Silver is not the only metal which forms Salts; there are Salts of Lead, Copper, Iron, etc. Sugar of Lead is a familiar instance of a Salt of Lead. It is a white crystalline body, easily soluble in water, the solution possessing an intensely sweet taste; chemical tests prove that it contains Lead, although no suspicion of such a fact could be entertained from a consideration of its general properties. Common Salt, or Chloride of Sodium, which is the type of the salts generally, is constituted in a similar manner; that is to say, it contains a metallic substance, the characters of which are masked, and lie hid in the compound. The contents of this Chapter may be arranged in three Sections: the first describing the Chemistry of the Salts of Silver; the second, the action of Light upon them; the third, the preparation of a sensitive surface, with experiments illustrating the formation of the Photographic image. SECTION I. Chemistry of the Salts of Silver. The principal Salts of Silver employed in the Photographic processes are four in number, viz. Nitrate of Silver, Chloride of Silver, Iodide of Silver, and Bromide of Silver. In addition to theae, it will be necessary to describe the Oxides of Silver. THE FEEPABATION AND PEOPEETIES OF THE NITBATE OF SILVEE. Nitrate of Silver is prepared by dissolving metallic Silver in Nitric Acid. Nitric Acid is a powerfully acid and...