5133 ~ -4 -2 0 2 4 (V20. V) / cm3mo1-' Figure 9. Relationship between V : -Y of decahydronaphthalenes and rrof solvents at 298.15 K (0) trans form; (0) cis form; (1) hexane, (2) cyclohexane, (3) carbon tetrachloride, (4) chloroform, (5) benzene, (6) Pd' ioxane.than that of cis form. The values listed in Table I demonstrates that in every case V2(cis) < V:(trans) and that the relative magnitude of the volume difference { V:(cis) -Y:(trans))/ V:(trans) takes the similar values (2.9-3.5%), irrespective of the compressibility of solvent system. This relative magnitude of the volume difference is in fairly good agreement with the result (4.3 -4.5%) shown in Figure 2.In Table 11, it is apparent that the partial molar volumes of hexane and d i o x a n e are independent of the conformation of the solvent decahydronaphthalene. This fact corresponds to the results calculated for the condition of constant pressure and shown by the symbol A in Figure 8.
Relationship between V : and KT of Solvents. It is interestingto examine eq 8 using the experimental results. Instead of V,Owe have plotted in Figure 9 the values of AY = V: -Yof decahydronaphthalene against experimentally determined KT values of the solvents. The correlation between AVand KT is evident.Thus we may say that amount of variation of V: values with solvent is principally determined, at least for nonelectrolyte solute dissolved in nonionic solvents, by the compressibility of the solvent.In conclusion, we have succeeded in predicting the observed Y, O behavior of transand cisdecahydronaphthalene by combining the RISM calculation and the Kirkwood-Buff theory.Registry No. trans-Decalin, 493-02-7; cis-decalin, 493-01 -6; hexane, 110-54-3; p-dioxane, 123-91-1.
References and Notes(1) Nomura, H.; Ohba, M.; J. Phys. Chem. 1989, 93, 8101. (2) Ohba, M.; Nomura, H.; J. Phys. Chem. 1991,95, 1399. ( 3 ) Chandler, D.; Andenen, H. C.In addition to the well-known vitreous but unfreezable water fraction of up to 0.3-0.4 (g of water)/(g of protein), a further water fraction of between ~0 . 4 and 0.7 (g of water)/(g of protein) was vitrified in samples of hydrated methemoglobin by moderate rates of cooling of up to =170 K min-I. The latter type of water started to crystallize at ~2 1 0 K to cubic ice and at =240 K to hexagonal ice as seen by X-ray diffraction. Measurements by differential scanning calorimetry have shown that this vitreous but freezable water fraction undergoes, on reheating at a rate of 30 K min-I, a glass-liquid transition with an onset temperature of 169 f 2 K, with a width of =14O and an increase in heat capacity of =30 J K-' (mol of crystallizable water)-l but that the glass transition disappears upon crystallization of the freezable water. Similar behavior has been reported recently for water imbibed in the pores of a hydrogel. The vitreous but freezable water fraction must be either due to water in sukwquent layers or due to water enclosed in pores and/or loops of the protein's chains. Its similarity in behavior to water in the pores of a hydrogel is suggesti...