632 HANDBOOK OF PHOTOGRAPHY 



particularly during hot weather. Too short immersion, however, prevents even 

 absorption of chemicals throughout the full depth of the gelatin layer, and this ordi- 

 narily results in large irregular color patches particularly noticeable in the blue-green 

 image. These irregularities are readily avoided by treating the tissues in the first bath 

 for a full 3-min. period. 



Type II Solutions (Using Acetic and Hydrochloric Acid; 



Stock Solution A 



Potassium dichromate 1 oz. 28 g. 



Potassium ferricyanide 1 oz. 28 g. 



Potassium bromide ., 1 oz. 28 g. 



Water (distilled) to , 20 oz. 566 cc. 



Stock Solution B 



Glacial acetic acid 1 oz. 35 cc. 



Hydrochloric acid (c.p.) 1 oz. 35 cc. 



Formaldehyde 22 oz. 770 cc. 



Water (distilled) IJ'z oz. 50 cc. 



Working Bath 1 



Stock solution A 1 Part 



Water 3 parts 



Working Bath 2 



Stock solution B 1 Part 



Water 32 parts 



While it is comparatively simple to carry through small carbro prints by the two- 

 solution method, it becomes decidedly awkward when prints larger than 8 by 10 in. 

 are to be handled. 



Since the single-bath method in which the controlling chemicals are mixed with 

 the bleaching and hardening agents has all the conceivable advantages with adequate 

 control, it will be described in detail. 



The manner of handling carbon tissues applies naturally to both methods. 



C.\RBRO Solutions for Single-bath Method 



Type I Solutions (Autotype) 



Stock Solution A 



Potassium bromide 1 oz. 28 g. 



Potassium ferricyanide 1 oz. 28 g. 



Potassium dichromate 1 oz. 28 g. 



Water (distilled) to. . . 20 oz. 566 cc. 



Stock Solution B 



Chromic acid 150 gr. 9.7 g. 



Chrome alum 300 gr. 19.4 g. 



Water (distilled) to 20 oz. 566 cc. 



Working Bath 



Stock solution A 1 Part 



Stock solution B 1 Part 



Water 3 parts 



Type II Solutions 



Stock Solution A 



Potassium bromide 1 oz. 28 g. 



Potassium ferricyanide 1 oz. 28 g. 



Potassium dichromate J^ oz. 14 g. 



Water (distilled) to 20 oz. 566 cc. 



Stock Solution B 



Glacial acetic acid 1 dram 3.5 cc. 



Hydrochloric acid (c.p.) 1 dram 3.5 cc. 



Formaldehyde (40 per cent) 10 drams 35 cc. 



Water 12 drams 42 cc. 



For convenience of accurate measurement the stock solution B could be made up in 

 one-third the normal strength or 



