This thesis describes testing of an electrostatic precipitator that has a portion of the main precipitator flow drawn through a porous (fabric) collecting surface. Tests investigated effects of flow through the collecting surface (side flow) on precipitator turbulence and particulate removal efficiency. Particulate removal tests were conducted at both ambient temperature and boiler slipstream conditions. Side flow was shown to reduce turbulence in the boundary layers of the collecting plates, but to have no significant effect on turbulence in the main gas stream (beyond the boundary layer). Side flow was shown to create a more uniform horizontal velocity profile within the precipitator. Side flow was shown to have little effect on the reentrainment of single particles, but appears to reduce reentrainment of an established dust layer. Reentrainment was shown to be an important concern primarily for particles greater than three micrometers in diameter. This research strongly indicated the advisability of using two stage electrostatic precipitation for the collection of particles less than three micrometers in size. / Master of Science