* 2 plastic transparent glasses, * Mineral water , * Tap water, * Black paper or cloth, * Marker.
Fill one plastic cup with mineral water and the other with tap water and label them with marker accordingly. Place both the cups in direct sunlight and place the black paper or cloth behind the cups. Just note what you see on the sides of the cup and brim in each cup.
Ultra-violet rays are more readily absorbed by mineral water which is seen as a blue fluorescent light. Tap water does not remit out this light.
The mineral water contains a blue fluorescence on its surface, which is not seen in the cup of tap water. The ultra-violet light is absorbed by the quinine in mineral water and is re-emitted as visible blue fluorescence light.