These experiments were inaugurated by the Louisville Water Company in connection with the manufacturers of certain patented filters. Mr. Charles Hermany, Chief Engineer of the Company, had general charge of the experiments. Mr. George W. Fuller was Chief Chemist and Bacteriologist and had direct charge of the work and has made a most elaborate report upon the same. In these examinations many devices were investigated; but the two which particularly deserve our attention are the filters known as the Warren Filter and the Jewell Filter.

These filters were operated for two periods, namely, from October 18, 1895, to July 30, 1896, and from April 5 to July 24, 1897. The investigations were directed toward the clarification of the river water from the mud, and to the removal of bacteria. The water was substantially free from color. The character of the water at this point was such that in its best condition at least three fourths of a grain of sulphate of alumina were necessary for its coagulation, and with this and with larger quantities of coagulant fair bacterial purification was nearly always obtained. The problem studied therefore was principally that of clarification from mud. The average efficiencies, as shown by the total averages, (page 248,) were as follows: Warren filter, bacterial efficiency, 96.7 per cent; Jewell filter, 96.0 per cent.