The American annual of photography (1917) (14781655554)

Identifier: americanannualof1917newy (find matches)
Title: The American annual of photography
Year: 1917 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University



Text Appearing Before Image:
tol means theoutlay of a good deal of money—the ending of the war wouldmean competition with the European manufacturer and theAmerican manufacturer naturally is not taking any chances.We have been informed, however, that one of the largestworks in this country expects to be able to supply metol underanother name in a few months so that the supply is not likelyto vanish from the market. Working to find a cheap and satisfactory substitute formetol in the form of some altered developer which was athand, the possibility of the use of some of the caustic alkalies,instead of the alkaline carbonates, was tried, as being ofgreater activity. These hydrates, sodium, lithium and potas-sium, respectively, have never been used to any great extentpartly on account of the action on the skin—and partly becauseof a certain softening of the film, as well as a prejudice againststrong alkalies. They are generally regarded by the non-chemist as simply stronger carbonates (that is stronger alkalies 126
Text Appearing After Image:
THE END OF THE VOYAGE. C. E. WAKEFORD. 127 than the carbonates) while in their action they bear no resem-blance to the carbonates. Dr. Andresen first discovered their pecuHar action, and thewell known developer Rodinal is the best known applicationof the hydroxides to developers. Von Hubl in Die Ent-wicklung der photographischen Bromsilber Gelatinplatte beizwiefelhaft richtiger Exposition has given the true explana-tion, of this action in the developer at some length. The hydro-gen in the hydroxyl groups of the phenol or naphthol develop-ers can be replaced by potassium, sodium or lithium, whereasthe alkaline carbonates simply make the solution alkaline with-out changing the nature of the developer. In other words, thehydrates or hydroxides form saltlike compounds which willdevelop even when nearly neutral, although they work betterwhen they are slightly alkaline, while the carbonates formdevelopers which must be alkaline in order to develop in anordinary lifetime. These developers fr