COLOR PHOTOGRAPHY 649 



sure, of course, was made through the celhiloid support and the development was 

 carried out with a tanning developer such as 



Water 1000 cc. 



Metol 1.5 g. 



Hydroquinoiie 1 . 5 g. 



Sodium sulphite (dryj 2 g. 



Sodium carbonate (dry) 17 . 5 g. 



Potassium bromide 1 . 5 g. 



or 



Water 1000 cc. 



Hydroquinone "1 8- 



Sodium sulphite (dry) 2 g. 



Sodium carbonate (dry) 15. 5 g. 



Potassium bromide 1 g- 



or 



Water 1000 cc. 



Pyrocatechin 2 g. 



Sodium sulphite (dry) 2 g. 



Sodium hydroxide 1 . 5 g. 



Potassium bromide 1 g. 



or 



Water 1000 cc. 



Pyrogallol 2 g. 



Sodium sulphite (dry) 16 g. 



Sodium carbonate (dry) 8 g. 



Potassium bromide 0. 5 g. 



These developers do not keep because of the small quantity of sulphite and 

 should therefore be made up just before use. 



Immediately after development and without fixing, the silver images were passed 

 into a bath of hot water in which the emulsion, not affected by the tanning action of 

 the developer, washed away, leaving the colored image in relief. The black silver 

 image was subsequently removed by any of the well-known reducers. The color 

 images were later transferred and registered on a final support in the order — yellow, 

 magenta, and blue-green. 



Although remarkably beautiful results were obtained from this process, it did not 

 meet with any degree of success for reasons not attributable to the process itself. 



Recently a very similar process has originated in Germany and is being marketed 

 throughout the world under the trade name Duxochrome. 



The Duxochrome color films are obtainable in packages containing an equal amount 

 of the three colors. The speed of Duxochrome film is approximately that of an ordi- 

 nary bromide paper. Exposure for this film also must be made through the celluloid 

 support, and the magenta and yellow emulsions require appreciably longer exposure 

 than the blue. The ratio of exposure is, roughly; blue, 1 ; magenta, 2; yellow, 3. The 

 developer recommended is the one supplied by the manufacturer of the color film and 

 is put up in two separate packages to make up stock solutions A and B. 



The processing of Duxochrome film is best carried out by first preparing the various 

 solutions necessary in a stock form from which the working solutions can be quickly 

 prepared by simple dilution. The following stock solutions are necessary: 



Stock solution A and B are made up in accordance with directions in the container. 



Stock Solution C 



Potassium metabisulphite 12 oz. 



Plain water (warm) 24 oz. 



Stock Solution D 



Potassium ferricyanide 1 oz. 



Plain water (warm) 36 oz. 



