March 23, 1900.] 



SCIENCE. 



457 



of bacteriology in connection with medi- 

 cine was noted, over the condition as found 

 in the first volume of Minerva (1892). 



(The full details of this investigation 

 will be found in the Jov,rnal of the Boston 

 Society of the Medical Sciences, Vol. IV., p. 67 

 et seq. ) 



On the changes of opinion in England in favor 

 of bacterial 2niriJication of seivage : Profes- 

 sor L. P. KiNNICUTT. 



Professor Kinnicutt described recent ex- 

 periments conducted in England which 

 are producing a change in opinion as 

 to the best method of treating sewage. 

 Whereas, hitherto the chemical method of 

 treatment has been commonly used, the be- 

 lief is now rapidly gaining ground that the 

 purification of sewage by bacterial growth 

 offers the cheapest and -most eflBcient method 

 of purifying it so that it may be discharged 

 into rivers without polluting them. 



Recent work on sewage purification involving 



bacteria: H. W. Clark. 



The paper brought out clearly the fact 

 that the benefit derived from preliminary 

 anserobic bacterial action upon sewage be- 

 fore filtration has been recognized at the 

 Lawrence Experiment Station for several 

 j'ears, and calls attention to statements 

 made, and investigations upon this point 

 recorded in the reports of the Station for 

 1895 and 1896 (see report of Massachusetts 

 State Board of Health for these years). It 

 gives credit to Cameron for first practical 

 use of anaerobic action with his septic tank 

 at Exeter, England. Results of investiga- 

 tions upon production and purification of 

 septic sewage at the Lawrence Experiment 

 Station during 1897 and 1898 were given, 

 with a comparison of intermittent sand 

 filters and bacterial or contact filters. 

 Rates of filtration of septic sewage, equal 

 to 300,000 gallons per acre, have been at- 

 tained with sand filters at Lawrence, and 

 of 800,000 with contact filters, with satis- 



factory purification. Investigations at Law- 

 rence during 1898 have shown that open 

 septic tanks are as successful as those made 

 air-tight, owing to the scum of bacterial 

 growths, fat, etc., formed over the surface 

 of the sewage. Some experiments made at 

 the Station seem to indicate strongly that 

 anaerobic action may be carried to such a 

 point that the resulting sewage is very difS- 

 cult to purifj''. 



The paper also gave the result of an ex- 

 periment in which sewage during 1898 was 

 passed through a filter of broken stone ten 

 feet deep, at the rate of one million nine 

 hundred thousand (1,900,000) gallons per 

 acre daily, with very satisfactory results, 

 nitrification being active, purification satis- 

 factory, and the rate of filtration more than 

 twice as great as ever before attained at 

 Lawrence with crude sewage. 



The significance of the ajjpearance of B. Coli 

 communis in filtered water : H. W. Clark • 

 and S. D. M. Gage. (Read by H. W. 

 Clark.) 



The purification of polluted waters by 

 sand filtration has been studied at the 

 Lawrence Experiment Station for the past 

 thirteen years. Up to the beginning of 

 1897 the efiiciency of the filters in remov- 

 ing bacteria was ascertained by determina- 

 tions of the actual number of bacteria in 

 the water applied to the filters and the 

 efiiuents from them. For the past three 

 years determinations of the number of B. 

 coli C07nmunis in the applied water and 

 efiiuents have been made. Especially has 

 the efiiciency of the Lawrence City Filter 

 in removing this germ from the Merrimac 

 River water been carefully followed. This 

 was done, as it was believed that the sig- 

 nificance of the appearance of the germ in 

 the filtered water could be determined be- 

 cause of the opportunity presented of study- 

 ing its appearance in connection with the 

 occurrence or non-occurrence of cases of 



