6 PHOTOGRAPHIC FACTS AND FORMULAS 
FLEXIBLE LANTERN SCREEN.—TJTake: 
Glycerine 16 parts 
White glue 16 parts 
Zinc oxide 32 parts 
Hot water 10 parts 
All are to be weighed. Dissolve the glue in the hot water and 
add the zinc oxide, ground up with the glycerine. Apply hot 
to the screen. A screen 10 feet square requires about 160 
ounces. 
To BrackEN ALUMINUM.—Clean perfectly free from 
grease by washing in soda solution, wash well, and immerse 
in: 
Ferrous sulphate 1 part 
Arsenious acid 1 part 
Hydrochloric acid 12 parts 
Water 12 parts 
When the colour is deep enough, dry with fine sawdust, and 
lacquer. This solution is intensely poisonous. 
BLACK FOR CAMERAS.—This may be used for wood or 
leather, inside or out: 
Nigrosine, spirit soluble 2.52 37 BF; 
Bismarck brown 0.65 g 10 gr. 
Denatured alcohol or 
methylated spirit 3.0 ccm 50 min. 
Aniline 29 ccm 1 oz. 
Heat the dyes with the alcohol until dissolved, and then add 
the aniline; apply with a brush and dry before the fire or in 
the sun. Or, for a dead matt varnish, lampblack may be 
rubbed up with gold size or shellac varnish, using as little of 
the liquid as possible; then thin down with turpentine. 
INK FoR BottLes.—The following formula gives a water- 
proof ink, and either black or white ink can be made by using 
lampblack or zinc white. 
