All entirely new method had previously been perfected (1) for the determination of molecular weight of cellulose acetate in solution. The applicability of the dielectric dispersion method to other cellulosics was the next step in the development of this new procedure. Ethyl celluloee fractions were refractionated by a fractional precipitation procedure in order to obtain fractions that were homogeneous with respect to chain length. Ethyl acetate and acetone were used in the ratio of three to one (3:1) as solvents, and water acetone in the ratio of ninety-five to five (9515) was employed as a precipitating agent. The homogeneous ethyl cellulose fractions were investigated in a number of solvents – dioxane, benzene, toluene, carbon tetrachloride and n-butyl acetate. This was done in order that the applicability of different solvents could be observed as well as the relation between the viscosity and the critical frequency. The critical frequency is defined as the frequency at which the dispersion is fifty percent completed. 1. Havkine, M. C., Master of Science Thesis, Virginia Polytechnic Institute, 1956. / Ph. D.