Abstract. The speed of sound in mercury, c, for frequencies between 9.5 and 10.5 MHz, has been measured by comparison with a frequency-stabilized infrared laser. For 75 mm diameter mercury columns with lengths L from 50 to 400 mm, temperatures T between 21.5 and 29.2 °C, and pressures P up to 230 kPa, the results are given in mm/s by c = 1449441 [1 - 3.032 × 10^-4 (T-23) + 1.42 × 10^-10 P - 1.8 × 10^-8 (L-400)] with a total uncertainty of 4.3 parts per million. These results have not been corrected for diffraction effects and the length L does not include that of a 10 mm beryllium buffer disk between the mercury and the ultrasonic transducer. The indicated length dependence is expected to decrease as the length increases beyond 400 mm.

The apparatus and techniques used for both the ultrasonic and optical measurements are discussed, along with details of the error analysis.

Print publication: Issue 3 (1987)
Received 22 December 1986