I want to perform a demonstration (I used to have it from a kit, but lost it) and I can't remember what the reagents were...can anyone help? The experiment was done safely by kids at room temperature and created a colorless solution that turned blue (though any color is fine) with the addition of a few drops of another colorless solution- Then the blue color could be made to disappear with the addition of another few drops of another chemical- anybody know what the chemicals may be and what would be the best way to go about purchasing them for demonstration?