  The heat capacity of solid Kr-CH4 solutions with 30 and 60 mol.% CH4 has been
studied at 0.8-20 K. The contribution of the rotational subsystem Crot to the
heat capacity of the solutions is separated. The results obtained in this study
and Ref. [4] were used to estimate the difference between the lowest-level
energies of the nuclear spin A and T modifications of CH4 and to find the
characteristic conversion times for the solutions with 5-60 mol.% CH4 at low
temperatures.
