Identifier: americanannualof1918newy (find matches)
Title: The American annual of photography
Year: 1918 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
tbooks. Paramidophenol has many other applications other than photographic, namely: as the basis for the manufacture of a series of dyes, for pharmaceutical preparations, and also as a . chemical re-agent. The use of paramidophenol as a photographic developeroriginated with Dr. M. Andresen about the year 1888, andsince that time the developer has attained wide popularity, andbeing suitable for plates and papers. Commercially, it is met with on the market under the fol-lowing names as a basic salt, viz.:—Unal; and as a solution incitol and rodinal. In the form of a hydrochloride as kodelon.And as the sulphate in emergol, kathol and duitall.Also in the form of a citrate. From a practical viewpoint the hydrochloride, sulphate andcitrate are found to be identical in their characteristics. Theobject of exploiting paramidophenol in the form of a salt isfor the reason that the basic salt is not soluble in water andthat these salts are readily soluble in cold water, more so inhot water. 240
Text Appearing After Image:
HIS MOTHERS ROSARY. R. E. SCAIFE. 241 ■V-. Paramidophenol is soluble to the extent of i part in 90 partsof water; this solubility is not much increased by temperature.The salts are readily soluble in alcohol, insoluble in ether andchloroform—the free base being readily soluble in causticalkaline solutions. It comes in the form of white crystals or plates, melting at184° C. (with decomposition). Development with paramidophenol results in a negative re-markably free from fog or stains (even an old solution). An aqueous solution of paramidophenol keeps well forsome time, darkening in color with age. When diluted withwater, however, it assumes a reddish tinge, and very slowlyloses its developing properties, but if diluted with a 5 to 10%solution of sodium sulphite instead of water, it will keep quitewell for some time. Many photographers fail to get density with paramido-phenol, simply because they do not develop long enough. Theimage appears rapidly, but gains density slowly (as in

Note About Images