With the aid of a microscope and a video camera, settling particles have been observed when passing a classical point-plate arrangement and, because of the deflection in the electrical field, impacting on the wall. As the cinematographic studies show, the particles arriving form agglomerate chains orientated along the electrical field lines and increasing to a critical length, dependent on the electrical operation conditions. In the video tapes, it is clearly seen that agglomerate chains of critical length are pulled off by the electrical forces. The observed agglomeration phenomenon is governed decisively by the particle material itself, in particular particle resistivity. Graphite and limestone particles, and glass spheres in the size range around 30 mu m have been investigated. In order to illustrate this electrically stimulated agglomeration the whole process has been video taped. These mainly phenomenological investigations reveal the physical background of a successful electro-mechanical two-stage system for the separation of diesel soot particles.