The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Aniline Prooess
stains or dyes in photographic processes; also in orthochro-matising plates and making light filters.
Aniline Process. In 1865 Willis patented this process which consists of impregnating paper with ammonium bichromate and phosphoric acid, drying, and then exposing under a positive to the action of light, and subjecting it to the fumes of aniline, by which means aniline colours were formed. H. W. Vogel sug-gests the following method of procedure: -
Sensitising Solution.
Potassium bichromate ... ... ... 1 parts.
Phosphoric acid, Sp. Gr. 1-124 ... ... 10 ..
Water           ...... ... ... ... 10 ..
Good paper, such as Rives or Saxe, is allowed to float on this for one minute, and then quickly dried. It is then exposed under negative or line drawing, and developed by placing in the bottom of a box, to the lid of which is affixed a sheet of blotting paper impregnated with commercial aniline 1 part, benzine 16 parts. The image appears fairly quickly (in a few minutes), and of a greenish-blue black, which turns to blue when the prints are soaked in water. If the fuming is carried on for some time the tones become blacker. With over-exposure the ground becomes tinged, and this may be removed by alternately bathing in dilute sulphuric acid (1 per cent.) or in hydrochloric acid (5 per cent.), and washing and then bathing in dilute ammonia. Philippe suggested, in 1884, floating gelatinised paper on 10 per cent, solution of bichromate of potash and ammonia. After exposure the print is laid in 1 per cent, solution of potassium cyanide till the whites are clear, then rinsed and developed in
Aniline          ............... 10 parts.
Oxalic acid ... ... ... ... ... 10 ,,
Water           ...............100 ..
In 1866 Endemann suggested the use of vanadic acid. Well-sized paper is sensitised with
Salt..................    480 grains.
Potassium bichromate ... ... ...    480 ,,
Sodium vanadiate ... ... ... ...    320 ,,
Water          ...............      20 ozs.
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