318 EXPERIMENT STATION RECORD. 



Infusoria exerts no bactericidal effect. Only living Colpodse are able to clear 

 the emulsions. 



" Direct sunlight does not prevent the clearing of the emulsions by the 

 Infusoria, but temperatures below 10° C. and above 30° C. and absence of oxy- 

 gen (anaerobic culture) are unfavorable to their exerting a bactericidal effect. 



" The polluted water of the canals of Amsterdam slightly delayed the clearage 

 of the emulsions; the sewage of starch factories and gas factories completely 

 prevented this clearage. 



" Consequently under natural conditions Infusoria will only play a part in 

 purifying river water (1) if the temperature is above 10° and under 30° C, 

 (2) if the aquatic vegetation is rich enough to supply the necessary quantity of 

 oxygen, (3) if the water is not highly polluted by adjoining factories." 



Sewage pollution of interstate and international waters with special refer- 

 ence to the spread of typhoid fever, A. J. McLaughlin {Pub. Health and Alar. 

 Hasp. Serv. U. 8., Hyg. Lab. Bui. 83, 1912, pp. 296, charts 91, maps. 39).— This 

 report deals with Lake Superior and St. Marys River; Lake Michigan and the 

 Straits of Mackinac; I^ake Huron, St Lawrence River, Lake St. Clair, and the 

 Detroit River; and Lake Ontario and St. Lawrence River. See also a previous 

 report (E. S. R., 25. p. 720). 



It is shown that " there is an undue prevalence of typhoid fever in many 

 cities and towns in the drainage basin of the Great Lakes. This excessive prev- 

 alence of typhoid fever, especially in the winter and spring months, is due in 

 greatest measure to sewage pollution of interstate and international waters 

 used as a source of public water supplies. Given the sewage pollution of the 

 source of supply, the excessive prevalence is made possible by the use of such 

 water unfiltered and untreated or by the faulty operation or poor efficiency of 

 filter plants. Most of the cities with excessive prevalence of typhoid fever use 

 unfiltered surface water as a public supply, although disjisters have occurred 

 where inefficient filtration was being depended upon to make a polluted water 

 safe." 



The suggested remedy for the conditions described is, therefore, the substi- 

 tution of carefully filtered or treated supplies " for the present polluted or 

 dangerous public supplies where adequate protection of such supplies against 

 pollution is not feasible." Specific advice is given on this point. 



The Berlin sewage farms (43,009 acres), H. A. Roechling (Jour. Roy. 

 Sanit. Inst., 33 (.1912), No. 5, pp. 118-206). — This is a more detailed account of 

 the work of these farms during the year ended March 31, 1910, than that pre- 

 viously noted (E. S. R., 26, p. 317). An important practical fact emphasized 

 in the article is that in addition to efficiently purifying the sewage the farms 

 paid a net profit of $2.66 per million gallons of sewage handled. 



Irrigation with sewage (Engin. Rcc, 65 (1912), No. 3, pp. 82, 83). — ^A plea 

 is made for better utilization of the fertilizing matter of sewage, and the general 

 proposition is advanced that better results from an economic standpoint could 

 bo obtained by quick handling of fresh sewage in a large number of small plants 

 rather than by one large plant involving more or less decomposition and loss of 

 fertilizing matter in the sewage. In an editorial, commenting on this proposal, 

 the practical difficulties in the way of utilization of sewage for fertilizing 

 purposes are concisely stated. 



The struggle with sewage sludge, W. Naylor (Surveyor, J/ 1 (1912). No. 

 106!i, pp. 818-821, fig. 1). — The article reports a number of analyses of sludge 

 and discusses its value as fertilizer, more particularly certain recently pro- 

 posed methods for preparing the sludge in improved form for this purpose. 



The most important improvement brought about by these methods is the 

 reducing of the sludge to a light friable material free from excessive water 



