Scientific amusements . easily procured by an indiarubber tube,or in a bag supplied for the purpose. Almost any objectscan be used, photographs, etc., etc., and many very comicalarrangements can be made. We have -lately ^een reading a curious method of?obtaining light from oyster-shells in a Trans-Atlanticmagazine. We give an extract wherewith to close thischapter. The compound is luminous paint. It has been known that certain compounds of limeand sulphur had the property of absorbing light, and givingit out again when placed in the dark. A simple way todo this is to expose clean oyster-shells
Scientific amusements . easily procured by an indiarubber tube,or in a bag supplied for the purpose. Almost any objectscan be used, photographs, etc., etc., and many very comicalarrangements can be made. We have -lately ^een reading a curious method of?obtaining light from oyster-shells in a Trans-Atlanticmagazine. We give an extract wherewith to close thischapter. The compound is luminous paint. It has been known that certain compounds of limeand sulphur had the property of absorbing light, and givingit out again when placed in the dark. A simple way todo this is to expose clean oyster-shells to a red heat forhalf an hour. When cold, the best pieces are picked outand packed with alernate layers of sulphur in a crucible,and exposed to a red heat for an hour. When cold, themass is broken up, and the whitest pieces are placed ina clean glass bottle. On exposing the bottle to brightsunshine during the day, it is found that at night itscontents will give out a pale light in the dark. Such a GHOST ILLUSION. 139. 140 OPTICAL APPARATUS. bottle filled more than a hundred years ago still gives outlight when exposed to the sun, proving the persistencyof the property of reproducing light. Very many experi-ments have been more recently made in this direction,and the light-giving property greatly enhanced. Thechemicals, ground to a flour, may now be mixed withoils or water for paints, may be powdered on hot glass,and glass covered with a film of clear glass, or mixedwith celluloid, papier-mache, or other plastic a paint, it may be applied to a divers dress, to cards,clock dials, signboards, and other surfaces exposed tosunlight during the day; the paint gives out a pale violetlight at night sufficient to enable the objects to be readilyseen in the dark. If the object covered with the preparedpaint is not exposed to the sun, or if the light fades inthe dark, a short piece of magnesium wire burned beforeit serves to restore the light-giving property.
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
