In this video we show how to make fluorescein, a strongly fluorescent chemical.
Combine 166 mg of phthalic anhydride, 220mg of resorcinol and 3 drops of concentrated sulfuric acid. Heat to 200 degrees celsius for 5 minutes. The crude fluorescein produced is dissolved in dilute sodium hydroxide solution (300mg in 10mL of water). To demonstrate fluorescence a few drops of the solution are dropped into water under ultraviolet light.