286 PHOTOGRAPHIC FACTS AND FORMULAS 
Water 1000 ccm 16 oz. 
Heat to 21° to 28° C. (69° to 83° F.). The larger the 
quantity of zinc oxide the warmer the tone. Or: 
Potassium oxalate 200 g 3% oz. 
Acid ammonium phosphate 25g 200 gr. 
Cupric sulphate lg 8 er. 
Water 1000 ccm 16 oz. 
The following complicated developer has also been recom- 
mended: 
A. Potassium oxalate 250 g 4 oz. 
Water 1000 ccm 16 oz. 
B. Cupric chloride 32 ¢ 125 er. 
Water 1000 ccm 8 oz. 
C. Mercuric chloride 62.5 ¢ 1 oz. 
Water 1000 ccm 16 oz. 
D. Lead acetate l6g 32 gr. 
Water 1000 ccm 4 oz. 
Add 12 parts of A to 4 parts B, then 4 parts C to 1 part D, 
and heat until the precipitate first formed is redissolved. 
Use at a temperature of 80° C. (176° F.). 
LocaL DEVELOPMENT.—By thickening the developer with 
glycerine, it is possible to develop cold-bath prints locally, 
so as to obtain various effects. Paint a sheet of glass larger 
than the print with glycerine, thinly and evenly. Use four 
teacups or saucers; fill A with pure glycerine; B, with 
glycerine 10 parts, saturated solution of potassium oxalate 
1 part; C, with glycerine 10 parts, saturated solution of 
potassium oxalate 5 parts; D, with saturated solution of 
potassium oxalate. Lay the print face up on the glycerined 
glass, and dab into contact with a pad of clean linen. Paint 
the whole of the print with the pure glycerine, using a long- 
handled soft brush, and allow to soak for 3 minutes. Sat- 
urate the brush with the B mixture and paint over the whole 
