178 PHOTOGRAPHIC FACTS AND FORMULAS 
Ammonium or potassium 
sulphocyanide 3.9 ¢g 30 gr. 
Boiling water 1000 ccm 16 oz. 
Dissolve the gold in half the water, add to the sulphocyanide 
dissolved in the remainder, and use when cold. A very con- 
venient stock solution can be made as follows: 
Potassium sulphocyanide 24¢ 184 gr. 
Water 400 ccm 634 oz. 
Heat to 98° C. (208° F.), and add slowly with constant 
stirring: 
Chloride of gold 8g 61 gr. 
Strontium chloride 80 g 614 gr. 
Water 400 ccm 6'4 oz. 
This should be heated to the same temperature. Allow to 
cool, filter, and wash the filter with: 
Water 200 ccm 2 oz. 
For use mix 1 part with 19 parts of water. The stock solu- 
tion must be kept in the dark. Sulphocyanide baths are 
rather apt to give double-toning, that is, blueish high lights 
with brown shadows. The following bath is free from this 
defect : 
Chloride of gold lg 7.7 gr. 
Salt 20 g 154 gr. 
Sodium sulphite, dry 0.5 ¢ 3.84 gr. 
Water 1000 ccm 16 oz. 
This should be allowed to stand for an hour before use. 
Red tones can also be obtained by the use of the following: 
Ammonium sulphocyanide 5g 38.5 gr. 
Potassium iodide 0.10to0.15¢ O.8to1.15 gr. 
Gold chloride 0.25 g 1.92 gr. 
Water 1000 ccm 16 oz. 
Combined toning and fixing baths have found much favour, 
as the final tone is easily determined, which is not the case 
