182 PHOTOGRAPHIC FACTS AND FORMULAS 
Another process with a mercury salt, which is open to ques- 
tion as to permanency, is to tone with: 
Potassium chloroplatinite 3¢g 23 gr. 
Salt 20 g 154 gr. 
Water 1000 ccm 16 oz. 
Tone until a blue-violet colour is obtained; then rinse well, 
and tone again in: 
Mercury sulphocyanide 20 g 154 gr. 
Citric acid 20 g 154 gr. 
Gold chloride 3g 25 Se. 
Water 1000 ccm 16 oz. 
Wash well, and fix as usual. 
GoLp AND UrANiIuM.—This also gives blackish prints: 
Gold chloride 0.25 g 1,9 gr. 
Uranium nitrate 0.25 g 1.9 gr. 
Salt 4g 31 gr. 
Sodium acetate 4g 31 gr. 
Water 1000 ccm 16 oz. 
Dissolve the gold and uranium, and add sufficient sodium 
carbonate to neutralise the solution; then add the other in- 
gredients. Printing must be rather deep; a salt bath should 
be used prior to toning, and an alkaline bath for fixing. 
Uranium Toninc.—This gives more or less red tones, 
the so-called red chalk or Bartolozzi colours. Print rather 
deeply, immerse in a salt bath, wash well, and tone in: 
Uranium nitrate 2¢g 15.4 gr. 
Thiosinamine 10¢g 77 gr. 
Water 1000 ccm 16 oz. 
Wash thoroughly, and fix. 
PALLADIUM ToniInGc.—This gives sepias and warm blacks 
but is not generally used. 
Potassium chloropalladite 0.5 g 3.8 gr. 
Salt 5g 38.5 gr. 
