This study was initiated in an attempt to obtain some information on the behavior of trickling filter stones during and after placement in the filter bed in relation to the clogging of the filters. The standard Los Angeles abrasive test and a modified abrasive test were used to resemble the handling of the stone in the field. During the course of the study methods were developed to obtain the total volume of a sample, the volume of the voids in a sample, and a procedure for measuring the sizes of stones and void spaces. (Modified author abstract)