the type of filter holder, the pore size, poropsity, area, and thick-ness of the filter and the physical nature, particle aize, and amount of material deposited on the filter are the principal factors affecting separation of suspended from dissolved solids. "Dissolved solids" is the portion of solids that passes through a filter of 20 ไมโครเมตร (or smaller) nominal pore size under specified conditions."Suspended solids" is portion retained on the filter.