The authors conducted experiments on the solution of solid particles in agitated liquids in a series of geometrically similar agitators. A great variety of solid particles, including several kinds of spherical crystals, whose particle size, shape and density varied over a wide range, were used as solid samples. Pure water, dilute hydrogen chloride and aqueous solutions of gelatine, polyvinyl alcohol, sucrose and glycerine of various concentrations were used as liquids. Between the agitator speeds of Nf and Na, all the data were correlated by the following dimensionless equations. For solid particles with an unknown surface shape factor, (13) and for solid particles with a known surface shape factor, (14) where (24) and (10) These equations represent the general correlation of the variables involved in determining the magnitude of the rate of mass transfer in agitated liquid-solid systems, and are used-to estimate the mass transfer rate for any liquid-solid combination in a series of geometrically similar vessels and impellers.