Color is a result of the interaction of light with matter.
The color that a solution appears to the human eye can change depending on the nature of the light source used to illuminate it. Dilute the fluorescein solution by adding enough distilled or deionized water to reach the 500-mL mark on the beaker. Dilute the eosin Y solution by adding enough ethyl alcohol to reach the 500-mL mark on the beaker. Eosin Y is soluble in water, but the fluorescence is not nearly as strong in water as it is in ethyl alcohol. Dilute the rhodamine B solution by adding enough distilled or deionized water to reach the 500-mL mark on the beaker.