The first cycle - lower experiment - pertains to a heat engine, which produces work from a temperature difference (steam engine). The fourth, last, movement of the piston (adiabatic expansion, brown, insolated vessel) is on the way, but has been stopped. The lnp-lnV diagram is traversed clockwise and its closed (when finished) surface is the work produced per cycle.- The upper experiment shows the function of a heat pump. Three piston movements have already happened (adiabatic, isothermal compression; adiabatic expansion). The fourth movement will close the cycle, an isothermal expansion (blue walls of the vessel, water bath!). Here the lnp-lnV diagram is registered counter clockwise. Its surface pertains to the work taken up to raise a certain amount of heat from a lower to a higher temperature. The animated experiment shows all these details with the ensemble of molecules.