12 



The Philippine Journal of Science 



1916 



RELATION BETWEEN CHEMICAL AND BACTERIOLOGICAL DATA 



I have tried without much success to correlate the chemical 

 analyses with the bacteriological data at hand. It is noteworthy 

 that the water was almost constant in composition during the 

 period of observation, in spite of the enormous fluctuations (from 

 120 to 10,000) in the daily colony counts during that time. 



The chlorine content was almost constant, its slight variation 

 showing no traceable connection with the fluctuation in bac- 

 terial content. There was no apparent relation between chlorine 

 content and oxygen consumed. It is, therefore, evident that 

 except for sudden and great contamination the chlorine con- 

 tent of the city water supply is of little significance. 



Barnard ^^ and others have repeatedly pointed out that a, 

 high nitrogen content is not always an indication of contami- 

 nation and have shown the futility of isolated nitrogen deter- 

 minations. This is confirmed by the results obtained in this 

 laboratory and by a critical study of the work on the city water 

 supply previously quoted," in which there is no traceable con- 

 nection between the bacteria counts and nitrogen determinations, 

 though both showed great variations. 



The best indication of the purity of the water was probably 

 furnished by the oxygen-consuming capacity, which showed 

 a number of maxima and minima corresponding fairly well 

 with bacteriological data, but here, too, the agreement was 

 not very good. 



In short, little more than the rather trite statement that 

 in a series of determinations made at short intervals a high 

 bacteria count generally appears to be associated with a high 

 organic content seems to be justified. The truth of this is 

 further indicated by the following analysis of the results of the 

 studies on Manila water : 



Table XI. — Relation between bacterial content and oxygen- 

 consuming capacity. 



Se- 

 ries 

 No. 



Year. 



fl903-4. 



11903-4. 

 1915— 

 1915... 



Source. 



Tap 



do.... 



Reservoir. 

 do — . 



Oxygen 

 , con- 

 sumed. 



>1.5 

 <1.5 

 >1.0 

 <1.0 



Average 

 colony 



count per 

 cubic 

 centi- 

 meter. 



360 



195 



4,300 



3,400 



Determi- 

 nations. 



5 



18 

 10 



7 



■Eng. Rec. (1913), 68, 297. 



' Bliss, Pub. P. I. Bur. Govt. Lab. (1905), No. 20, 10. 



