Measurement of the temperature of density maximum of water solutions using a convective flow technique

A technique is described which yields an accurate measurement of the temperature of density maximum of fluids which exhibit such anomalous behaviour. The method relies on the detection of changes in convective flow in a rectangular cavity containing the test fluid. The normal single-cell convection which occurs in the presence of a horizontal temperature gradient changes to a double cell configuration in the vicinity of the density maximum, and this transition manifests itself in changes in the horizontal temperature profile across the cavity. The method is applied to a variety of water solutions.