Abstract
The assumptions made by Hall and Herzfeld in previous theories of ultrasonic absorption are interpreted on the basis of a new and more general analysis. The formulae given by them are discussed, and it is suggested that the conditions implicit in Herzfeld's formula should be modified. By this modification a new relation is derived, which provides a satisfactory explanation of the observed relaxation effects in those liquids which have been studied.
A method of `curve fitting' is employed to compare experimental results with theoretical requirements. Finally, it is concluded that the ultrasonic behaviour of acetic acid and propionic acid is governed by the excitation of bending vibrations of carbon-hydrogen bonds. Measurements in carbon disulphide indicate that in this case also a bending vibration is responsible. Some incomplete data for toluene suggest that here a stretching vibration of the carbon-hydrogen bonds in the methyl group is involved.