Magnetosedimentation of particles in heterogeneous colloids

When binary mixtures of colloidal particles settle under gravity the structure of the sediment is a function of the relative dimensions and densities of the particles. All this is changed if the colloids are allowed to settle in an attractive vertical field gradient. Here, the particles acquire a contribution to the effective density which results in selective magnetosedimentation. A description is given of exploratory settling experiments of this type, using binary mixtures of paramagnetic materials. In certain of these experiments clear evidence of sediment bands is found.