OIL AND BROMOIL 303 
way of making these bleachers is to keep the ingredients in 
separate 10 per cent stock solutions, and mix as required. 
The best results are obtained with freshly made prints. Old 
prints should be soaked in water at 20° to 25° C. (68° to 
77° F.) until quite limp, or the bleaching bath should be 
raised to these temperatures. Fresh solution should be used; 
repeated use of the same solution leads to irregularities. 
Bleaching may take from 5 to 30 minutes, according to 
temperature and composition of the bath. With those baths 
containing potassium ferricyanide, a subsequent treatment 
with 5 per cent sulphuric acid is advisable. After bleaching 
the print should be washed and fixed in a 10 per cent hypo 
solution containing 214 per cent sulphite, or 15 per cent hypo 
with 114 per cent metabisulphite. If there is any sign of a 
coloured residue in the image, especially in the shadows, it 
may be removed by treatment with 2%4 per cent sulphuric 
acid, and the print washed, or the following may be used: 
Thiocarbamide 25g 192 er. 
_ Ammonium persulphate 25g 192 er: 
Water 1000 ccm 16 oz. 
The prints should be washed for about ten minutes, then laid 
face up on a sheet of glass, the surface gently dabbed with a 
soft linen pad to remove any surface moisture, and should 
then be dried. 
BLEACHING BAaTHs.— 
1 2 3 4 5 6 U 8 
Potassium bichromate 22.5 18.2 10 8 (t) 8 10 29.5 
Potassium bromide 11.25 10.0 Us q 10.3 15 3 
Potassium ferricyanide 11.25 10 20 10 2.3 10 3 59 
Potash alum 45 36.4 10 0.5 th 40 10 ate 
Ammonium alum ba is ne 20.5 Hie aie 
Oitric acid 11.25 10 High 1 
Salt Ae a 53 
Glacial acetie acid aN he 7—14 
Hydrochloric acid z ae ae Be 3 15 a ay 
1. Hewitt; 2. Rennie; 3 Weissermel; 4. Schmidt; 5. Garner; 6. Rennie; 
7. Rennie; 8. Quentin. 
After the print has been bleached in the above baths, it should be immersed 
in a 5 per cent solution of sulphuric acid for 5 minutes, and then washed. 
