By means of ultrasonic light-diffraction phenomena the velocity and absorption of sound in some forty transparent liquids were measured in the frequency range of 6 to 30 Mc. Among the list of materials studied are mixtures of liquids in varying proportions, several solutions of solids in liquids, and a nonliquid jell. A novel-construction glass-to-metal-to-quartz cell made possible the study of highly solvent liquids. Velocity values were obtained from measurements of the diffraction spectra spacing. Absorption values were obtained by measurement of the sound radiator voltages required to produce certain color transmission effects at measured distances from the sound radiator. The use of a mercury arc light-source enhanced the necessary color effects. The relation between sound beam width (in the optical direction) and light transmission was studied. In general, the values of velocity obtained were found to be independent of frequency, and the absorption to be proportional to frequency squared and unrelated to calculated viscous and thermal losses. A simple calculation is proposed for estimating absorption errors caused by sound beam diffraction and spreading. These apply as well to absorption measured in other methods than here used.