34 GEORGE W. FULLER 



In Germany numerous experiments have been made upon the 

 sedimentation of sewage for purposes of clarification, and the so- 

 called biological methods have been studied for some years, begin- 

 ning in 1895, when a testing station was established by Professor 

 Dunbar at Hamburg, which station is still in operation. In 1901 

 the Prussian government established a permanent organization 

 for testing water- and sewage-purification methods. This "insti- 

 tute" has gathered together and published the more important 

 data as to experiences in other countries, has conducted several 

 important sewage-testing stations in the suburbs of Berlin, and has 

 collated many useful data as to the sanitary works of the cities of 

 Prussia and neighboring territory. This department has an annual 

 appropriation of about $30,000 for testing, inspecting, analytical, 

 and clerical purposes. The sum devoted to testing purposes varies, 

 but is materially supplemented by the arrangement of conducting 

 investigations for various local authorities, the expense for which 

 is borne in part by the community benefited. The department 

 also established the custom of officially examining proprietary 

 devices, largely at the expense of the owners in cases where the 

 devices seem to possess sufficient merit. In this way a mechanical 

 filter of the Jewell type was recently tested at the Muggelsee plant 

 of the Berlin water-works. The same filter is now being tested 

 on the colored water supply of Konigsberg. 



The relative amounts of suspended matters deposited from sew- 

 age at different velocities have been studied carefully under vary- 

 ing local conditions at Frankfurt, Cassel, Hannover, and Cologne, 

 as shown by the data published in municipal reports and the technical 

 press. In these cities, as in England, it is difficult to ascertain 

 the cost of the tests, because so much of the work was done by the 

 regular staff of the technical authorities of the cities. The scope 

 of the tests has probably been greatest at Frankfurt, including means 

 for most easily removing sludge, its partial drying by centrifugali- 

 zation, and its ultimate disposal by incineration after mixing with 

 the city refuse. About $60,000 has been spent at Frankfurt on 

 these and other sewage tests, including filtration, within the past 

 dozen years or more. 



Professor Dunbar 's activities in the field of sewage purification 



