288 PHOTOGRAPHIC FACTS AND FORMULAS 
parts B. Intensification will be complete in about 15 minutes. 
Intensifying with gold (Dollond)—The print should be 
placed face up on a sheet of glass, and, if previously dried, 
must be soaked in water first. Dab into flat contact with a 
clean linen pad, and paint the surface with glycerine, using 
a soft brush. Then pour on the surface a few drops of a 1.5 
per cent solution of gold chloride and paint rapidly over with 
the brush. As soon as the desired intensity is reached, rinse 
under the tap, and sponge back and front with a normal metol 
developer diluted with an equal volume of water. There 1s 
some danger of the white assuming a pink or blueish tint with 
this process. 
ToniInG PLATINOTYPES.—Platinum prints can be toned 
with uranium, iron, and catechu. The first gives brownish- 
red tones, the second blue, and the third browns. For the 
uranium toning the following stock solutions are required: 
A. Uranium nitrate 100 g 768 gr. 
Glacial acetic acid 100 ccm 768 min. 
Water 1000 ccm 16 oz. 
B. Potassium ferricyanide 100 ccm 768 gr. 
Water : 1000 ccm 16 oz. 
C. Ammonium sulphocyanide 500 g 3840 er. 
Water 1000 ccm 16 oz. 
For use add 10 ccm A to 1000 ccm water (77 min. to 16 oz.) ; 
then add 10 ccm (77 min.) C and, finally, 10 ccm (77 min.) 
B. Instead of the sulphocyanide, 5ccm (35 min.) of a 10 
per cent solution of sodium sulphite may be used. The well- 
washed print should be placed in a dish, well flooded with 
plenty of the solution, and the dish rocked until the desired 
tone is obtained. On the slightest sign of the solution becom- 
ing cloudy, pour off and apply fresh; otherwise the whites 
will be stained. 
The iron toning requires: 
