A critical exponent of an aniseed-based liquor

We present the results of a simple experiment suitable for the undergraduate laboratory in which the onset of turbidity when an aniseed-based liquor is diluted with water is observed. The optical transmission shows the behavior typical of the order parameter in a second-order phase transition. The changes in the transmission are due to the precipitation of terpenes and the amount of precipitated terpenes also shows critical behavior of the form n = k′(c - cc)y, where c is the fraction of water in the solution. The critical exponent is determined to be y = 1.01±0.06. © 1996 American Association of Physics Teachers.