Many experiments in which surface tension could play a significant role are conducted with Rhodamine B solved in a fluid in order to perform visualization and non-intrusive quantitative techniques. I did a small survey in order to find if someone has never quantified the effect on surface tension of rhodamine B's concentration in water. I know the effect of a concentration of 1.25e-5 mg/l RhB in ethanol, but I couldn't find anything for water.