A technique reported by Barone and Nuovo has been adapted to the measurement of ultrasonic absorption in liquids. The output of an rf transmitter is 100 percent modulated at an audiofrequency and applied to a crystal. This results in a periodic variation of the radiation pressure in the acoustic beam. A condenser microphone has been constructed, employing a front face consisting of a thin sheet of plastic, coated with silver paint. The microphone responds to the audiofrequency variation radiation pressure, and its output is preamplified and then detected on a harmonic analyzer. The apparatus has been tested in water in the frequency range 9 to 30 mc, and the measured values of the absorption coefficient agree with the accepted values within a few percent. Measurements of the absorption coefficient have been carried out in a number of uni‐univalent electrolytic solutions.