I have my introductory physics students determine the index of refraction of various solids using fairly conventional methods (lining up pins or determining critical angle). I think this experiment would be more interesting if I could vary it more. I would like to find a substance with the following properties: * Inexpensive * Safe * Transparent to most visible wavelengths * An index of refraction outside the range of 1.4 to 1.7 (almost all glasses and clear plastics seem to be in this range) I've considered using big ice cubes (n = 1.31). Jello is about 1.38, so it's not much of a change. Cubic zirconia is over 2, but I can't find slabs of that. Ideas?