Apparent molar volume data for solutions of cellobiose and water are reported for 25, 35, 45, 55 and 65 O C . Osmotic coefficients were determined at 0 and 25 O C . Theories of dilute solutions are applied to solute-solvent and solute-solute interactions, assuming a rigid particle model for the repulsive potential.Sucrose and cellobiose are disaccharides of the same molecular formula but differing ring structures. Cellobiose is 4-0-( P-D-glucopyranosy1)-D-glucopyranose and sucrose is a-D-glucopyranosyl-P-D-fructofuranoside. They apparently have the same number of hydroxyl groups available for bonding in aqueous solution but differ considerably with respect to their solubilities in aqueous solution. Sucrose is ca. 5 times as soluble as cellobiose at 25 OC and dissolves much more quickly. Values for the solute-solvent and solute-solute interactions can be calculated from thermodynamic properties on the basis of rigorous statistical mechanical theories1* Information on the solute-solvent interaction is obtained from the partial molar volume of the solute at infinite dilution; data for the osmotic coefficient of the solvent then give values for the solute-solute interaction. It was decided to obtain these data for cellobiose and compare them with existing data for sucrose to try and throw some light on the problem.

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