TONING 463 



Bleach completely in 



Solution A 



Potassium ferricyanide 2 . 5 g. 38 gr. 



Glacial acetic acid 5 . 5 cc. 96 minims 



Water 250 cc. 9 oz. 



Wash well and tone in 



Solution B 



Uranium nitrate 2. 5 g. 38 gr. 



Water 240 cc. 8 oz. 



Wash well in water free from alkali. 



Green Tones. — By a combination of iron ferrocyanide and silver sulphide green 

 tones may be obtained. For this method the following stock solutions are required. 

 For green tones: 



Solution A 



Potassium ferricyanide (red prussiate of potash) 5 g. 77 gr. 



Ammonia 5 drops 5 drops 



Water to make 100 cc. 3J^ oz. 



Solution B 



Iron and ammonium citrate ferric 2 . 2 g. 33 gr. 



Hydrochloric acid (concentrated) 5 cc. 80 minims 



Water to make 100 cc. 3H oz. 



Solution C 



Sodium sulphide (pure crystal) 1 g. 15 gr. 



Water 100 cc. 3K oz. 



Hydrochloric acid (concentrated) 5 cc. 80 minims 



In toning the following procedure should be followed: The thoroughly washed 

 print is completely bleached in solution A. After washing has removed all the stain, 

 print is immersed in solution B for about 5 min. Again the print is washed and then 

 placed in solution C for about 5 min. Print should be washed again after removing 

 from this solution and dried in the usual manner. 



Dye Toning. — It is possible to replace the normal silver photographic image with 

 one consisting primarily of a colored dye. In such a process the metallic silver is first 

 converted into a mordant, such as silver ferrocyanide, which has the ability to attract 

 and hold many basic dyes. The following mordanting bath is one recommended 

 by Dr. B. T. J. Glover., in his book, "Lantern Slides," and although it is 

 intended for lantern slides and film positives it may be used in some instances for 

 paper prints. 



Mordanting Bath. Stock Solution 



Uranium nitrate 8 g. 70 gr. 



Oxalic acid 4 g. 35 gr. 



Potassium ferricyanide t . 4 g. 35 gr. 



Water to 11. 20 oz. 



The chemicals are each dissolved separately in 5 oz. of water, and the solutions 

 added together in the following order: oxalic acid, uranium nitrate, potassium ferri- 

 cyanide, and finally water to make the required quantity. The solution when pro- 

 perly compounded should be of a pale-yellow color; and because of its light sensitivity 

 should be stored in the dark. For use, 1 part of this stock solution is diluted with 

 4 parts of water. 



The positive after fixing and washing is placed in the mordanting bath until the 

 black silver image has been converted to a light-brown color. It is then washed to 

 remove the yellow stain and transferred directly to the following "dye" solution: 



