Ultrasonic (us) and dielectric (d) relaxation measurements in 2-butoxyethanol in the temperature range + 25 to −40°C are presented and discussed. It is found that the us spectra consist of a main, exponential relaxation process superimposed on a low-frequency one located in the submegahertz region. The d relaxation exhibits a Cole-Davidson behavior which supports the presence of an additional process in the GHz region. The characteristic times (τu and τd) for the main us and d relaxation bands are of the same order of magnitude and they noticeably increase as temperature decreases following an Arrhenius-type behavior. The overall results, together with specific heat and viscosity data, suggest that the relaxation processes are associated with the aggregation of few alcohol units (dimers or trimers) or to internal motions (rotational and/or bending). The formation of long-living cyclic structures is supported by the low-frequency us spectra as well as by the relative low values of the dielectric constant.

Brillouin scattering spectra in water both in the normal and in the metastable (supercooled) regions are investigated. The experimenal data are extended for the first time in a bulk sample down to -27.0\ifmmode^\circ\else\textdegree\fi{}C. A refined analysis method allows the authors to obtain hypersonic absorption and velocity. The data are briefly analyzed in the frame of both a relaxation process and a heterophase-fluctuation hypothesis.

On looking at the experimental findings on the thermodynamic properties of ordinary liquid water in supercooled state, we find that they can be consistently interpreted if a new contribution due to heterophase fluctuations is superimposed to a «regular» behaviour as given by a reliable extrapolation from the stable region. The «monomer» liquid which transforms into ice nuclei is associated with a «close packed» component of a two-state model interpreting the bulk medium extrapolated properties. By supposing that the amount of ice clusters depends onTM−T, whereTM is the melting temperature, we find a simple relationship between the slope of the liquid-solid equilibrium curve and the heterophase fluctuation contributions to the isothermal compressibility and thermal-expansion coefficient. The consequences are discussed and compared with sound velocity experiments in water and with the behaviour of thermodynamic properties in other supercooled liquids. A substantial agreement is found.