94 SEWAGE AND ITS PURIFICATION 



*' when an effluent containing upon an average 800,000 bacteria 

 per c.c. is passed through a depth of 4 feet of soil at a slow 

 rate (150,000 to 400,000 gallons per acre per twenty-four hours) 

 there is a very great reduction in the total numbers and in the 

 J5. coUr 



When the effluent was inoculated at intervals with cultures 

 of B. typhosus or of B. anthracis, tests for these organisms in the 

 filtrate were negative. B. pyocyaneus, similarly added, was 

 observed to die out in the filter. 



