180 Elements of Water Bacteriology. 



found that the bacteriological examination offers a more 

 delicate and a more certain index of the quality than 

 may be obtained by chemical analysis. In a number of 

 instances, springs located in pastures have become slightly 

 polluted by animals, but to so small an extent that the 

 chemical examination gave no indication of trouble. 

 The bacteria, however, increased greatly in number, and 

 colon bacilli could be readily isolated from 75 per 

 cent of the i-c.c. samples of a long series used in 

 making the presumptive test. A single case may suffice 

 as an illustration. This was a spring located on a hill in 

 Hopkinton, Mass. 

 The chemical analysis was as follows: 



Color None 



Turbidity None 



Sediment None 



Odor (hot) None 



Odor (cold) None 



Parts per Million. 



Total solids 33-oooo 



Loss on ignition 7.0000 



Fixed residue 26.0000 



Hardness f 11.0000 



Chlorine * 10.0000 



Nitrogen as 



albuminoid ammonia o.oooo 



free o.oooo 



nitrites o.oooo 



nitrates o.oooo 



The bacteriological examination showed a total count 

 of 375 bacteria per c.c. and a 37-degree count of 350 

 per c.c. 



