Concerning the transformation temperatures, the values obtained were 225.7 " 0.4, 250.1 " 0.4 and 245.5 " 0.5 K for II-Ib, Ib-L and Ia-L, respectively. The corresponding enthalpy changes were determined to be 4.68 " 0.10, 2.53 " 0.05 and 1.82 " 0.04 kJ mol y1 , respectively. Temperatures as well as enthalpy changes agree with **data** published elsew x where 4,15,16 . 3 3 w x According to Rudman and Post 2 the crystal system of the OD stable phase, solely from X-ray Ž . diffraction evidence of CH CCl for n s 2, 3, 4, 3 4yn n could be indexed as cubic. However, an optical examination of the crystals indicated to Rudman and Ž . Post that ''only CH CCl was optically isotropic''. 3 3 w x Recent measurements 9,10 have shown that birefringence is not zero for this phase. Nevertheless it must be pointed out that such a parameter also has a contribution due to the anisotropy of the polarizabil-Ž . ity of the molecules called molecular birefringence .