Abstract
Concentration-dependent diffusivities of Ficoll and methyl cellulose (M-278) in aqueous solution were measured by a microinterferometric method for solute concentrations ranging from 0.050 to 0.700 g solute/ml of solution for Ficoll and from 0.050 to 0.200 g solute/ml of solution for methyl cellulose. Empirical formulas for the diffusivity and an activity coefficient of each solute are presented as a function of solute concentrations.