Once the entire solution is mixed, place the gelatin mixture into the refrigerator and let it rest for about 4 hours or until firm Then, take out your solid gelatin and place it under a blacklight. You should see it glow!
What is going on?
Why does this gelatin glow? The active ingredient in tonic water is quinine, a fluorescent substance. This means that it becomes excited as it absorbs energy from other light sources and then releases light as it returns back down to its calmer, natural state. In this case, the quinine absorbs the energy from the UV light and emits some of that energy back in the form of visible blue light. This is what gives your gelatin its glow!