Tonic water contains an ingredient called QUININE. This chemical compound, originally used as a remedy for malaria phosphoresces under a black light dues to its chemical composition.
Tonic water is an aquired taste. However, when it is mixed with other liquors, mixers, and chilled almost anyone can enjoy it. The beauty of this drink is that it is remarkably radiant and will glow even if you mix it with other liquids.
If you are going to use tonic water make sure the cups you buy for your party are see through. SOMETIMES the cups you buy also phosphoresce under a black light. If you really want to get creative try adding tonic water to your test tube shots to make them glow.