Ž Accurate measurements with acquisition times of . Ž . 1 320 min show that the OD phase Ib of CH CCl 3 3 is isostructural with phase Ib of CCl . According to 4 the unambiguous similarity of the patterns, the phase Ib of methylchloroform was indexed and lattice parameters corresponding to a rhombohedral structure w x R were determined to be a s 14.584 A and a s 89.498 at 232.2 K. The characteristic temperatures and enthalpy changes associated with the II-Ib, Ib-L and Ia-L transitions were found to be in accord with the w x published **data** 4,17 . The transition temperatures are 224.0 " 0.2, 241.9 " 0.2 and 235.8 " 0.3 K, respectively. The associated enthalpy changes are 7.38 " 0.12, 2.31 " 0.03 and 1.55 " 0.03 kJ mol y1 , respectively.