Abstract
A pulse technique has been used to measure ultrasonic absorption and velocity in liquid bismuth and mercury at temperatures up to 450 °C and at frequencies of 68 Mc/s and 92 Mc/s. In each of these metals the measured absorption is found to be higher than the absorption deduced solely from considerations of shear viscosity and thermal conductivity. The bulk viscosity which is introduced to account for the excess absorption is attributed to structural relaxation. The ratio bulk/shear viscosity is 4.5 in liquid bismuth and 1.3 in mercury and appears to be independent of temperature.