Compressibility of Liquid Sodium—Potassium Alloys

Abstract
The velocity of sound has been measured in the sodium—potassium alloy system as a function of both composition and temperature. For each composition the velocity was found to be a linear function of the temperature. The behavior of the compressibility, because of the volume contraction on alloying, cannot be explained in terms of a free electron model. A possible explanation is that changes in the electronic charge density upon alloying gives rise to both the volume contraction and the slight positive deviation in the compressibility.