28 PHOTOGRAPHIC FACTS AND FORMULAS 
Pinacyanol 2 ccm 15 min. 
Water 1000 ccm 16 oz. 
As all the isocyanines are decolourised by the carbonic acid 
dissolved in water, this bath would be rapidly decolourised, 
and in this state would not give such good results. A small 
addition of ammonia or borax is essential. In the above 
baths the dyes are used in 1: 1000 alcoholic stock solution. 
George's Formula.— 
Pinaverdol 13.75 ccm 105 min. 
Homocol 9ccm 69 min. 
Pinacyanol 11.5 ccm 88 min. 
Ammonia 68.75 ccm 528 min. 
Alcohol, 90% 376 ccm 6 oz. 
Water to 1000 ccm 16 oz. 
This bath is too strong in ammonia. The dyes in the above 
bath should be used in a 1: 2000 alcoholic stock solution. 
Monpillard’s Formula.— 
Pinacyanol or dicyanine 5 ccm 38 min. 
Homocol 5 ccm 38 min. 
Ammonia 0.1 ccm 0.77 min. 
Water 1000 ccm 16 oz. 
With dicyanine the sensitiveness extends to 750, with pina- 
cyanol to 680. Stock dye solution 1: 1000 alcohol. 
DESENSITISING PLATES.—Luppo-Cramer found that by 
bathing plates in certain dye solutions both ordinary and 
colour-sensitive plates could be desensitised after exposure 
and thus be worked in a bright orange or yellow light without 
fog. Phenosafranine in a 0.05 per cent solution may be used 
with one minute’s bathing in the dark, or 10 per cent of a 
0.5 per cent solution may be added to the developer with 
equally good results. Other dyes of this class that act well 
are dimethylsafranine, amethyst violet, giroflé, safranine MN, 
phenosafranine and cresosafranine. Unfortunately, these 
