_ Printing-Out Papers 
GELATINO-CHLORIDE OR PrINTING-OuT Paper. — This 
paper, also called P. O. P. in England, is coated with an 
emulsion of silver chloride with an organic salt of silver and 
excess of silver nitrate in gelatine. The greater the ratio of 
organic salt, the more vigorous the prints. Many formulas 
have been suggested, some of which either give poor results 
or the paper has poor keeping properties, and they are, there- 
fore, omitted. The following will be found reliable. 
Abney.— 
A. Sodium chloride 13.5¢ 104 gr. 
Citric acid 8.5 g 65 gr. 
Potassium citrate 11S)35) 119 gr. 
Water 500 ccm 8 02. 
Gelatine 54g 415 er. 
B. Silver nitrate SL SO ar. 
Water 400 ccm 6Y4 oz. 
C. Chrome alum 0.6 ¢ 4.5 gr. 
Water 100 ccm 1¥4 oz. 
Soak the gelatine in the water for 30 minutes, melt at 50° C. 
(122° F.), and add B at the same temperature, stirring 
slowly; finally, add C. This gives a slow printing paper with 
very long scale of gradation and is most suitable for the 
combined bath. 
Barker.— 
A. Ammonium chloride 29's ZO a ot 
Rochelle salts 59¢ 45.25 gr. 
Citric acid 8.1¢g 62 ger. 
Alum ied 1S) sea 
Gelatine 136 g 1044 gr. 
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