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January 19, 2007
Q. At certain college parties, students will smear their bodies with Vaseline petroleum jelly or the cream filling of Twinkies snack food, while sipping tonic water. Can you shed some light on these doings?
A. These “Twinkies and Vaseline” parties use black light (ultraviolet light) from an ultraviolet lamp, says Jearl Walker in “The Flying Circus of Physics.” Some component of the jelly and cream filling, perhaps an aromatic hydrocarbon, fluoresces by absorbing the ultraviolet light and emitting visible blue light; likewise, quinine in the tonic water may help produce the eerie blue glow. Fluorescent paints on walls, t-shirts washed in “whiter-than-white” detergents, and black light posters can similarly captivate the eye.
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