When a longitudinal wave moves through a certain medium, the antity which is transmitted through the medium is

When a longitudinal wave propagates through a medium, it transmits energy only, not the material of the medium itself. In longitudinal waves, particles of the medium oscillate back and forth parallel to the direction of wave propagation. While these particles undergo temporary displacement through cycles of compression and rarefaction, they return to their original equilibrium positions after the disturbance passes. This means there is no net transport or permanent transfer of mass. Waves are fundamentally defined as disturbances that transfer energy and momentum from one location to another without the bulk movement of matter. For instance, in sound waves (a common longitudinal wave), energy is passed between molecules, but the air itself does not travel from the source to the listener. Thus, only energy is transmitted through the medium.

Sources

1. [1] https://www.sciencedirect.com/topics/physics-and-astronomy/longitudinal-wave