The excess volumes of (hexadecane + propanone) have been measured by dilution dilatometry at the temperatures T = 299.15 K and 305.15 K close to the directly determined upper critical solution temperatures T-UCS = 398.492 K. The isotherm closer to T-UCS displays the characteristically flat portion close to the critical mixture of volume fraction phi = (0.4821 +/- 0.0003) of hexadecane. The orthobaric density of carefully dried and purified propanone has been determined in a capillary pyknometer from T = 288.15 K to 323.12 K with results about 0.001 g . cm(-1) lower than older values but in good agreement with a more recent determination in which care was also taken to reduce the water content. The densities of (hexadecane + propanone) of known composition were determined pyknometrically at six temperatures from T = 294 K to 323 K : the results agree well with those calculated from our measured excess volumes, propanone densities, and dependable literature values of hexadecane density.