Large amounts of work have been carried out in the study of flow conditions of liquids since the classical work of Poiseuille in 1842. Numerous satisfactory methods of measurement have been used for the truly viscous liquids. In the study of colloidal dispersions these same methods of measurement and similar methods of calculation have been applied. With viscous liquids the shearing stress is directly proportional to the rate of shear, but this is not generally true for colloidal dispersions of the nitrocellulose type (Figures 4 to 8). Hatschek some time ago called attention to this fact. To account for the difference in behavior of viscous liquids and hydrophylic substances in dispersing medium, M. von Smoluchowski has considered the latter as highly solvated masses which enclose dead areas of liquid. When the solution is subjected to shear these particles deform and the liquid in the dead areas acts as a drag on free flow. Similar considerations have been brought forward and extended by R. Hess and W. Ostwald.