PLATINOTYPE 285 
foggy results are obtained. The stock solutions are: A, the 
normal potassium chloroplatinite solution; B, sodium ferric 
oxalate 50g (40z.), water 100 ccm (80z.); C, gum arabic 
50g (40z.), water 100ccm (80z.). The sensitiser is: 
Potassium chloroplatinite sol. 4 ccm 65 min. 
Sodium oxalate sol. 6 ccm 98 min. 
Gum sol. 4 ccm 65 min. 
Increased contrast may be obtained by the addition of sodium 
chloroplatinate or potassium bichromate solution as in the 
other processes. The paper must be dried quickly. Expos- 
ing the paper to steam after printing, if the image appears 
of sufficient depth only in the shadows, is of some assistance, 
but, at the best, it is not a satisfactory process. 
Sepia TONES BY DEVELOPMENT.—Ordinary hot bath paper 
may be developed to sepia by the use of the following devel- 
oper (Hubl): 
Potassium oxalate 100 g 768 gr. 
Potassium phosphate 50 g 384 gr. 
Citric acid 20 g 154 gr. 
Potassium chloride 10g 77 gr. 
Mercuric chloride 10¢g TG, ae 
Water 1000 ccm 16 oz. 
Use at a temperature of 80° C. (176° F.). Or the following 
may be used: 
Potassium oxalate 65g 500 gr. 
Potassium citrate LL 85 er. 
Citric acid l6g 123) or 
Mercuric chloride 6.75 g 52\iet: 
Water 1000 ccm 16 oz. 
Heat to 35° C. (95° F.). Or the following (Jacoby) may be 
used: 
Potassium oxalate 250 g 4 oz. 
Zinc oxalate 100 to 125g 800to 1000 gr. 
