REPORT OF EXAMINATION OF SAMPLES OF LAKE MONONA WATER. By E. J. TULLY, Chemist, State Laboratory of Hygiene, Laboratory of the State Board of Health. From examination of samples of Lake Monona water, it appears that the northern part of the lake is more polluted than the southwestern section in the vicinity of Brittingham Parkthe degree of pollution at the northern end decreases rapidly with increasing distance southeast of the outfall; the lake southwest of the bathhouse in Brittingham Park is practically free from pollution. In the vicinity of what may be termed the Bassett street sewer, however, the water is moderately polluted; but as the discharge from this sewer has been shut off, the quality of the water in the immediate vicinity will rapidly improve and soon be restored to its normal quality. The water at the bathing beach is only slightly polluted at this time; it is satisfactory for bathing purposes. It has been stated that the effluent from the septic tank at the bathhouse in Brittingham Park is discharged into the lake without any subsequent treatment. This effluent adds quite a little to the pollution of the water in the immediate vicinity of the bathhouse, and, as it is potentially dangerous, it should be treated with a disinfectant, such as chloride of lime, before discharging it into the water at the bathing beach. The only decided odor along the water front was in the vicinity of the sewage outfall near the mouth of the Yahara River. There will always be more or less odor in this neighborhood, particularly during the warm weather, as long as the practice of discharging the sewage effluent at the surface of the water is continued. The disagreeable odor so often complained of in this vicinity may be entirely eliminated-in so far as it is due to the sewage effluent and the general appearance of the water much improved, too, by discharging the effluent under the surface of the water in Lake Monona. To obtain the best results the effluent discharge pipe should be extended into the lake along the bottom, about 150 feet from shore, and the effluent discharged at such a point that complete intermingling of the effluent with the current from the Yahara River will be effected and the possibility of stagnation of the organic matter prevented. Such a procedure as this would ensure a greater immediate dilution of the septic effluent than obtains at the present time with the discharge taking place at the surface of the Yahara River; the putrescible and odorous compounds would at once be oxidized and dissipated, and the physical nuisance due to foul odors would be eliminated. REPORT OF THE INVESTIGATION OF THE WATER SUPPLY OF MERRILL, WISCONSIN. By E. J. TULLY, Chemist, State Laboratory of Hygiene, Laboratory of the State Board of Health. The analytical data afford ample conclusive evidence of the pollution, moderate in extent, of the Prairie River all along its course; the degree of pollution, of course, varies somewhat; it is always present, however, and to about the same extent a mile or so above the dam as it is in the vicinity of the water works intake pipe. The pollution is mainly of an animal nature and is derived directly, and indirectly through the agency of surface washings. There is, however, one source of human contamination below the dam, namely, bathing. Because of the potentiality by this means of seriously polluting the water within a quarter of a mile or so of the intake, bathing should be at once prohibited, and the prohibition should be strictly enforced. Bathing should be done not above the intake, as has been the practice, but below it. The effluent from the paper mills, discharged into the river below the dam, is not supposed to carry any sewage-only industrial waste is intended to be discharged through the river outlet pipe. It is a source of contamination, however, and the character of it should be closely watched. As the quality of the river water is practically the same above and below the dam, the extension of the intake pipe to some suitable point in the river at a considerable distance above the dam with the hope of obtaining a much more wholesome river water than is obtained at the present intake would be as uneconomical as it would be futile. There is no decided sanitary advantage to be gained by and no material justification for such an extension. A river water of decidedly better quality than that near the present water works intake may only be found miles above the dam, and, of course, extension of the intake pipe to such comparatively remote points is not to be considered as necessary. A potable public water supply of good quality should be sought for along the lines of increased efficiency in filtration rather than by the means of intake extension. Efficiency of the purification system is the essential requisite leading to the production of an acceptable supply. The investigation of the efficiency of the plant indicates that in general the operations are effectively conducted. The company is concerned to effect thorough treatment and to deliver pure and wholesome water; and it appears that in general the quality of the filtering water is satisfactory, although the color reduction accomplished is not all that could be desired. There is evidence, however, of irregularity in the operation of the system. Some of the data are of such a convincing nature as to lead to the conclusion that at times the water is imperfectly purified, and can not be regarded as acceptable. An entirely satisfactory bacterial purification and color removal may always be accomplished by proper treatment, yet, occasionally, effluents are discharged which are unsatisfactory as to color and bacterial content. The possibility of danger lies in this irregularity of operation which results in the delivery of water of fluctuating composition. As the pollution of the river water varies a good deal from time to time-it is contaminated to a higher degree in the spring and summer than in the winter-the necessity for uniformity of treatment is indicated; it is a fact that diseases other than typhoid may be affected by polluted waters, hence the necessity of efficiently purifying the river water, and maintaining a high standard of treatment at all times. In the management of the plant an amount of coagulant should always be added sufficient to remove practically all color from the river water-the color of the effluent should be maintained below 10 parts per million; and no effluent should be passed into the filtered water reservoir after a filter has been washed until its color index is below 10. The color index may be taken as a superficial measure of the efficiency of treatment. REPORT ON USE OF HYPOCHLORITE IN THE By E. J. TULLY, Chemist, State Laboratory of Hygiene, Laboratory of the State Board of Health. In view of the fact that the experimental work in connection with the installation of the hypochlorite process at Fond du Lac is about completed, and that practical treatment of the sewage effluent is now under way, it seems desirable at this time to submit a preliminary report of the investigation in the form of a synopsis. When the work was undertaken considerable difficulty was encountered at the very commencement with the hypochlorite delivery apparatus. It was soon discerned that the delivery apparatus, which was intended to be used with only one sewage pump, would not functionate at all properly and accurately under the influence of three pumps, which now, under the existing pumping conditions, may be automatically thrown into service whenever the demand necessitates their action. As I understand it, the additional pumps were added to the system after specifications for the hypochlorite process had been drawn up. As a result of this condition of affairs it was necessary to design and install a new arm for the delivery device, and adjust it so that the orifice would deliver approximately the required amount of hypochlorite solution. Of course, this delivery device can not be regulated so as to discharge proportionate amounts of hypochlorite over the entire range of flow of the sewage effluent over the weir; the most that may be hoped for with the present arrangement is to secure the proper addition of the disinfectant over the normal range of flow. Accordingly, with this aim in |