Die Messung kleinster Schallgeschwindigkeitsänderungen in Elektrolytlösungen mit dem Phasenvergleichsinterferometer

The phase-comparison-interferometer developed by Schaaffs and Kalweit has been used in order to examine the forecasts of the electrolytic theory as regards the velocity of sound in very dilute solutions with much more reliability than has been done before. All the possible errors have been considered in detail. The measured small changes of velocity of a few cm/s have not been determined by the usual, time-consuming process of averaging a number of observations but through individual observations in which such changes are indicated practically instantaneously on an oscilloscope. The first results are reported on solutions of NaCl and KCl in the concentration range 0 to 0,06 molar.