116 



The Philippine Journal of Science 



1916 



in Manila; and if the water be changed weekly, the danger of 

 contamination is very slight. 



Table X. — Effect of daily additions of 0.5 part of available chlorine per 



million parts of water. 



[Results expressed as parts per million.] 

 TANK I.»^ 



Age of water in days. 



Tur- 

 bidity. 



Qualitative test for free chlorine. 



Chlorine- 

 consum- 

 ing ca- 

 pacity, b 



Chlorides 

 (CD. 



Oxygen 



con- 

 sumed. 



1 







2.5 



5.6 



0.75 



2 .. 



8.4 

 8.5 

 9.5 

 7.0 



8:7 



8.5 



Strong 



3 _ 











4 



Faint 









5 











6 . 











7 



Paint 









8 





2.8 



1.1 



1.05 



0.7 



1.0 



1.0 







9 



8.8 

 8.1 

 8.8 

 8.5 

 9.1 

 8.5 









10 



Faint . . 







11 



do . 



1 



12 



do.... 







13 









14 



do 



13.0 



1.05 



15 







16 . 





























TANK III." 









1 



10.5 



8 

 11.5 



8.9 





2.5 



4.4 



1.42 



2 



Very faint 



3 



do - 









4 











5 . .. 











6 



9.9 

 9.1 





3.0 

 3.0 

 2.1 

 3.1 

 3.5 







7 









8 









9 



8.3 



8.5 









10 



. . 



12.2 



2.36 



11 





12 





Negative _ ' 





















• Tank I was chlorinated daily at 9 o'clock in the forenoon ; tank III at 4 o'clock in the 

 afternoon ; both were sampled at 6 o'clock in the afternoon and analyzed the following day. 



b Two hundred cubic centimeter samples digested two hours at 30° C. with 6.5 milligrams 

 available chlorine. 



It was inadvisable to keep the water in the tanks for more than 

 one week, for the additional reason that the amount of calcium 

 chloride introduced might prove objectionable. In the cases 

 under observation there was not the slightest complaint during 



