Abstract
When soluble matter is introduced into a solvent flowing slowly through a capillary tube it is dispersed longitudinally by a process which involves both the variation in fluid velocity over the cross section of the tube and radial diffusion by molecular agitation. Measurements of longitudinal dispersion provide a new means for measuring diffusion coefficients. Results obtained by this method will be given.
The stability of solutions contained in vertical tubes when the density increases upwards also depends on radial diffusion. Measurements of the equilibrium density gradient can be used as another new method for determining diffusion coefficients.
The mechanics of dispersion in turbulent flow through a pipe can be discussed by a method which is analogous to that used for streamline flow. The results of this calculation are compared with experiments in which brine was injected into water flowing in 3/8 inch and 40 inch pipes, and the subsequent dispersion along the pipe was measured. Similar comparisons are made with American measurements in long pipe lines.