Many of the properties of ethyl cellulose that make it useful in different ways are a result of the varying lengths of the cellulose chains arranged within the chain bundles. This investigation was undertaken in order to find a method of separating these ethyl cellulose chains into more homogeneous groupings and to determine the distribution of chain lengths. The conditions and procedure are to be so determined that the results from one fractionation may be duplicated in succeeding ones. A commercial grade of ethyl cellulose can be fractionated according to length of the chain, degree of polymerization, by the method worked out in this investigation. At the present time is it not known what effect dissolving the ethyl cellulose in 80% acetic acid and the subsequent treatments have had on the ethoxy content. It is possible for the degree of substitution to decrease from the first through the last fraction, but this is not considered likely in view of the distribution curve obtained. / M.S.