File:The American annual of photography (1922) (14779114954).jpg

Identifier: americanannualof36newy (find matches)
Title: The American annual of photography
Year: 1922 (1920s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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of some new chemicalcompounds of the phenolic type, was first called to the atten-tion of photographers by Mr. John H. Gear, Hon. F.R.P.S.,in the British Journal of Photography for May 27, 1921.The keeping properties of D50 according to Mr. Gear repre-sent a decided advance over any other known developing agent.Mr. Gear states that he has successfully used a solution ofD50 that has stood in an open tray for one week. He alsoclaims for it greater energy than most developers in ordinaryuse, and freedom from a tendency to cause fog. Tests con-ducted by Mr. Gear with Dr. Adolphe Abrahams, F.R.P.S.,the famous authority on high speq<d photography, seem toprove the especial value of the new agent for short exposuresMr. Gear recommends the following formula: Solution A. D50 Concentrated solution 240 minims Water to make 10 Oz. Solution B. Sodium Sulphite Dry 200 Grains Sodium Carbonate Dry 125 Potassium Bromide 5 Water to make 10 Oz. An important advance in the research work of the year 12
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uo <w H o w Q 13 which cannot help but have a large influence on future workingmethods is the discoveries of methods of reducing the sensitive-ness of plates so as to allow them to be developed in a brighterlight. The remarkable desensitizing properties of phenolsaf-ranine w^as first noted by Dr. Luppo-Cramer. On Jan. 3, 1921,Mr. Raymond E. Crov^ther published in The British Journalan account of his trials v^ith the same, and very shortly after-ward the Ilford Plate Co. put a compound called Desensitolon the market. Considerable attention has been paid not onlyto the scientific aspects of the matter, but also to its practicalapplication. The first is by no means settled. Dr. Luppo-Cramer considers desensitation as an oxidation phenomenon.M. Lumiere also found that the most effective desensitizerswere mild oxidants. However the restoration of the originalsensitiveness upon washing out the dye indicates that no per-manent change results. Lately M. Lumiere and Seyewetz(B. J. June loth

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