16 



MASS. EXPERIMENT STATION BULLETIN 446 



Table 7. — Summary of Results of Fermentation Tests for Coliform 

 Bacteria in Disposal Field Soils, 1945 and 1946. 



South 

 Tank 



Middle 

 Tank 



North 

 Tank 



Controls 



* False positive tests produced by bacteria not of the coliform group. 



Note: South tank, normal 24 hours retention; middle tank, 12 hours retention; north tank, 8 

 hours retention. Controls were soils from the same area that had not received sewage effluent. 



Table 8. — Analysis of Positive Coliform Tests From Table 7. 



South 

 Tank 



Middle 

 Tank 



North 

 Tank 



Controls 



Note: South tank, normal 24 hours retention; middle tank, 12 hours retention; north tank, 8 

 hours retention. Controls were soils from the same area that had not received sewage effluent. 



