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Luminous

paint, calcium and iron

LUMINOUS PAINT.—A phosphorescent luminous paint, consisting of roo parts by weight of carbonate and phosphate of calcium, (obtained by calcining sea shellst) mixed well together, too parts of pure lime and 25 parts of calcined sea salt, both measured by weight. Half the amount of the whole weight of sulphur is then incorporated by sublimation, and from five to eight per cent. of mono-sulphide of calcium or barium.

Balmain's luminous paint is a phosphorescent substance incorporated with a colorless var nish. The following directions for the manufacture of a luminous paint were recently given by a correspondent in Photography : substance is a calcium sulphide, and is easily prepared by cleaning thick oyster shells and then burning them until they are red-hot; when cool, roughly pound them and pick up all the black and dark pieces. When fairly clear, pound fine and place a layer of about half-inch thick in a suitably sized fireclay crucible, and then a layer of same thickness of flour of sulphur, then another of oyster shell ash, then sulphur, and so on until the crucible is filled to within one and a half inches of the top. Fill this space up with well-worked clay, and allow it to dry in a warm place; when dry, place the crucible and contents in the fire, and when a low blood red, endeavor to keep it at that for at least 6o minutes. Two hours would

be better if the clay luting is done well. Allow it to cool slowly and then turn out the contents and pound to a powder. This will give you a very bright luminous paint. If wanted for use as a water-color, by the addition of gum senegal dissolved in water, or if for outside use, copal gum dissolved in turps and one-fifth the bulk of poppy-oil added. The poppy-oil is to prevent it cracking. If it is to be applied to iron, the iron must first be painted with an oxide of iron paint. or the luminous paint will soon lose its luminosity." LuniNous PHOTOGRAPHS.—The late W. B. Woodbury used to make what he termed luminous photographs by exposing a piece of cardboard, coated over with a luminous paint, under a glass positive. The effect in the dark was very striking, a brilliant phosphorescent picture being the result.

Paper coated with luminous paint and exposed to light under a transparency will give a luminous picture in the dark. Of course the effect is not permanent.