The kinetic energy of the molecules of these gases must contain two terms in addition to those representing translational energy.
For a rigid body the kinetic energy will, in general, consist of three terms (AW1 2 +BW2 2 +CW3 2) in addition to the translational energy.
In fact the proved tendency for the gas to pass into the " normal state " in which there is equipartition of energy, represents in this case nothing but the tendency for the translational energy to become dissipated into the energy of innumerable small vibrations.
