142 PHOTOGRAPHIC FACTS AND FORMULAS 
Chloride of lime 6g 46 er. 
Make into a paste with a little water, and add to: 
Sodium carbonate, dry 4.5¢ 34 er. 
Water 250 ccm 4 oz. 
Shake thoroughly, filter, and wash the filter with successive 
portions of water to make the total bulk of the filtrate 
1000 ccm (16 oz.), then add: 
Chrome alum 4¢g 30 gr. 
Immerse the negative and rock the dish for a few minutes; 
then gently pass a pad of absorbent cotton, well wetted, over 
the surface. 
BICHROMATE.— 
Potassium bichromate 20 g 154 gr. 
Sulphuric acid 40 ccm 308 min. 
Water 1000 ccm 16 oz. 
Dissolve the bichromate, and add the acid. This has nothing 
particular to recommend it, and requires rather long washing 
to remove the yellow stain from the negative. 
PERMANGANATE (Namias).— 
Potassium permanganate 0.5 g 4 gr. 
Sulphuric acid 10 ccm 77 min. 
Water 1000 ccm 16 oz. 
It is preferable to mix this just before use, or stock solutions 
can be prepared by dissolving the permanganate in half the 
water, and the acid in the other half; the stock permanganate 
solution must be kept in the dark. This reducer acts evenly 
and can be used for prints as well as negatives. Should any 
brown stains appear, they may be removed by immersing the 
plates or prints in: 
Sodium sulphite, dry 75g 576 gr. 
Oxalic acid 30 g 230 gr. 
Water 1000 ccm 16 oz. 
Wash well after this bath. 
