The American annual of photography . suggests thatit is within the range of possibility that an orthochromatic platewhich does not require a screen may be produced by thismethod. Whatever may be the future developments of theprocess it is certain that it has come to stay, and that it isan advance of considerable importance to the practical pho-tographer. As most of the American magazines have pub-lished accounts of the practical working of the method I willrefer the reader to any of the following articles: AmericanPhotography, June 1921, page 328, Camera Craft, April, 1921,page III, Photo Era,
The American annual of photography . suggests thatit is within the range of possibility that an orthochromatic platewhich does not require a screen may be produced by thismethod. Whatever may be the future developments of theprocess it is certain that it has come to stay, and that it isan advance of considerable importance to the practical pho-tographer. As most of the American magazines have pub-lished accounts of the practical working of the method I willrefer the reader to any of the following articles: AmericanPhotography, June 1921, page 328, Camera Craft, April, 1921,page III, Photo Era, May, 1921, page 243, which is a reprintof the article of January 3 in the B. J. The production of panchromatic sensitiveness with mineralsalts by Capstaff of the Eastman Research Laboratory hasopened up a new field for exploration which may develop intoan extremely profitable one. Film bathed in a two per centsolution of sodium bisulphite, and followed by washing fromfive minutes to thirty hours, showed increasing sensitiveness 14. HOWARD GILES—ARTIST. G. W. HARTING. 15 to the red. Without the bisulphite bath washing in wateiconfers Httle or no sensitiveness. The addition of an alkahincreases the sensitiveness, while soluble bromides diminishthe action. The effect is due apparently to the sulphurous con-tent of the bisulphite. No satisfactory theory has yet beenfound. Messrs. Capstaff and Bullock attribute it to a partialreduction of the silver salt to collodial silver. Mr. F. F. Renwick has also found that potassium iodideand sodium and potassium cyanide have the same effect. Inthe Photo Journal January, 1921, he states that a very dilute(1-50,000) solutions of the former are sufficient to render theplate markedly red sensitive. Renwick considers that theaction is due to a change within the silver-bromide-iodide grainrather than anything akin to ordinary sensitizing by dyestuffs. Increasing the speeds of panchromatic plates by treatmentwith ammonia is the subject of some va
Size: 1518px × 1646px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1922
