Fluorescein

Fluorescein is an organic compound and dye. It is based on xanthene and belongs to triarylmethine dye family. 

It is available as a dark orange/red powder and used in water and alcohol. It is widely used as a fluorescent tracer. The color of its solutions is green by reflection and orange by transmission. 

References

Category:Aromatic oxygen heterocycles
Category:Carboxylic acids
Category:Ketones
Category:Hydroxyarenes