We have measured the lattice volume of ice VIII in different pressure-temperature pathways and found that the volume depends on the pathway, implying that deviatoric stress makes the volume larger. Dense ice is in the ice VIII phase with the molar volume of 6.56 cm(3) and in a high-pressure phase with the molar volume of 6.45 cm(3) at 10 K where the pressure can be estimated as 57.0 & PLUSMN; 3.4 and 60.4 & PLUSMN; 3.6 GPa, respectively, based on the third-order Birch-Murnaghan equation with parameters determined in this study (K-0 = 30.8 & PLUSMN; 1.3 GPa and K & PRIME;(0) = 3.7 & PLUSMN; 0.1 with V-0 fixed to 12.030 cm(3)).