File:The American annual of photography (1912) (14579327129).jpg

Identifier: americanannualof1912newy (find matches)
Title: The American annual of photography
Year: 1912 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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ossible to successfully compete withthe wet collodion process for black and white work. Al-though not on the market, both are accomplished facts.Whether they become monopolies to be worked by one largephoto-engraving concern, or whether an enterprising manu-facturing firm, which is not looking forward to immediategain, will secure and work them, will probably be settled inthe very near future. NEW SCREEN FOR COLLODION EMULSION. It is well known that collodion emulsion requires shorterscreen distances than wet collodion, which is due to irradia-tion effects. How to make use of this somewhat troublesomeproperty has been ably discussed by Mr. Howard Farmer,of the Polytechnic Institution, London, in his IrradiationProcess lecture some years ago. To avoid sweating ofscreen, small diaphragms were requisite and the exposureswere unduly prolonged. A series of troubles were directlytraceable to long exposures and subsequent drying of theemulsion film. The new screen introduced by Max Levy, 282
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BROOKFIELD MEADOWS. GEO. R. BOSWORTII. of Philadelphia, has a very thin cover glass, and allows ofvery close screen distances and large apertures. If we bearin mind that intensity of illumination cannot be compensatedfor by prolonged exposure the great value of the new screenbecomes self-evident, and cannot be exaggerated. The tend-ency of the high lights closing, due to spreading of light, issuccessfully overcome by increasing the width of the blacklines. A USEFUL COLOR PRESERVATIVE. Collodion emulsion, when sensitized with iso-cyanine de-rivatives, is liable to be affected by atmospheric impurities.Sulphuretted hydrogen, carbon dioxide, sulphur dioxide andnitrous oxides in the dark room or studio have caused trouble.A simple remedy has been found which we can stronglyrecommend. After washing the plate, flow three times with the follow-ing solutions before exposure: Distilled water 50 oz. Gum Arabic i^ oz. Glycerine 3^ oz. or 10 lumps of ordinary white sugar dissolved in one quartof

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