A sample of clinic dextran (Mn= 54,000) has been fractionated by precipitation at 25° C in the system water/ethanol. Seven fractions were isolated in the usual way and freezedried. Fitting of the molecular weight distribution to the exponential functions of Tung and Schulz gives a good approximation, but it is improved by using a linear combination of the exponential, logarithmic, and normal functions, according to a method recently developed.