The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Electrograph
Eliminators, Hypo-
being by means of one or several conducting wires. Most methods are based on the fact that selenium becomes more con-ductive under the action of light. Those wishing to study this problem should obtain Liesegang's M Beitrage zum Problem des Electrischen Fernsehen," published by the author at Diisseldorf, 1891. For a long list of references to original papers relating to kindred subjects, see The Amateur Photographer, July 19th, 1901, p. 45.
Electrograph. An apparatus by which a photograph may be telegraphed. It is based on the principle of Bakewell's Copying Telegraph. (See The Amateur Photographer, July 5th, 1901 ; also, see Electric Telephotoscopy.)
Electrotint. A term which has been applied to various methods in which half-tone printing blocks or plates are pro-duced by electrotyping.
Electrotyping. The formation of metal casts from a solution of the metal by electrolytic action, and largely employed in con-nection with the production of photomechanical printing plates. Useful information cannot be given in a few sentences, and the student should obtain Alexander Watts' " Electro-Metallurgy," 45., Electrician Office, Salisbury Court, Fleet Street.
Element. In chemistry a substance regarded as simple or non-decomposable. In optics often applied to one glass or lens of a complex system ; occasionally to an achromatised group in a system. (For list see Equivalence, Chemical.)
Elemi. A concrete resinous exudation from Canarium com-mune, a plant of Malay. It is sometimes used in the preparation of Varnish (q.v.).
Eliminators, Hypo-. Any salt or solution of salt used to get rid of the last traces of hypo from the films or prints. Many so-called eliminators have been recommended, as peroxide of hydrogen, eau de javelle, alum, iodine, acetate of lead, hypo-chlorite of zinc; but opinions seem to be about equally divided as to the benefit of their action. A recent introduction is the persulphate of potassium sold as anthion.
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