34 PHOTOGRAPHIC FACTS AND FORMULAS 
Erythrosine 10g 77 gr. 
Aurine 8g 61 gr. 
Ivory black 8g 61 gr. 
This will dry in 10 minutes and can be readily removed with 
a, damp sponge. 
QUICK-DRYING Soap BACKING.— 
Soap f 45¢ 346 gr. 
Denatured alcohol (methylated 
spirit ) 1000 ccm 16 oz. 
Erythrosine l4¢ 107 gr. 
Aurine l4¢g 107 gr. 
Scrape the soap into fine powder or shavings, digest in the 
alcohol for a week with occasional shaking, add the dyes, 
and filter. 
BACKING SHEETS.—Black or red paper, gummed or coated 
with dextrine on one side, may be used, but is less efficient 
than any of the others. Sheets that can be repeatedly used 
may be made by coating cloth or paper with: 
Soft gelatine 1 part 
Water 2 parts 
Glycerine 1 part 
Soak the gelatine in the water and melt in a water bath; add 
the glycerine, then add lampblack, nigrosine, water soluble, 
or ared dyetocolour. Or printing-out paper may be exposed 
to light until dark, then washed, dried, soaked in glycerine, 
and squeegeed to the back of the plate. 
OxGALL (Boras) .— 
Oxgall, purified 1 part 
Gum arabic mucilage 4 parts 
Red or black water colour 1 part 
The water colour should be obtained in a tube ground up in 
water. This should be applied with a stiff brush, and a sheet 
of black celluloid or paper applied. 
