XI, A, 1 



Heise: Water Supply of Manila 



rate of addition was employed at two different periods, the two 

 series of tests are recorded independently. 



Table VII. — Effect of 0.625 part available chlorine per million of water.' 



Date. 



1914. 



June 15 



June 16 



June 17 



June 18 



June 19 



June 20= 



June 21 



Reservoir. 



Colony Test for B. 

 count. coli group, b 



18 



55 



95 



240 



90 



450 



450 



Positive . 



do — 



do... 



do ... 



do ... 



do ... 



do ... 



Average reduction in bacteria count . 



San Juan. 



Colony Test for B. 

 count. coli group.*" 



4 

 12 

 42 

 110 

 14 

 170 

 325 



Negative . 



do .... 



do .... 



do .... 



do .... 



Positive — 

 Negative . 



Reduc- 

 tion. 



Per cent. 



78 

 78 

 66 

 54 

 84 

 62 

 28 



* Examination by O. Schobl, bacteriologist. Bureau of Science. 



•> In 2 cubic centimeter samples. Bacillus coli removed six out of seven times = 86 per cent, 



' Typhoon ; muddy v?ater. 



Table VIII. — Effect of 0.625 part available chlorine per million of water.^ 



Date. 



1914. 



June 29. 

 June 30. 

 July 1 .. 

 July 2 .. 

 July 3 .. 

 July 4 .. 

 July 5 .. 

 July 6 .. 

 July 7 .. 

 July 8 .. 

 July 9 .. 



Reservoir. 



Colony 

 count. 



180 



90 



12 



12 



150 



210 



750 



600 



1,900 



120 



130 



Test for B. 

 coli group.b 



Positive — 



do .... 



do .... 



do .... 



do.-.. 



do .... 



Negative . 

 Positive .. 



do — . 



do.... 



do .... 



San Juan. 



Colony 

 count. 



Test for B. 

 coli group. b 



Negative... 



do 



do 



contaminated. 



18 

 10 

 46 

 85 

 1,000 

 95 

 120 



Average reduction in bacteria count . 



Negative ... 



do 



do 



do 



do 



do 



Positive 



Reduc- 

 tion. 



Per cent. 

 69 

 39 

 67 



94 

 94 

 86 

 47 

 21 

 8 

 61 



' Examination by O. Schobl, bacteriologist. Bureau of Science. 



*> In 2 cubic centimeter samples. Bacillus coli removed eight out of nine times = 89 per cent. 



The greatest addition of chloride of lime, representing 0.75 

 part of free chlorine per million of water, was employed for only 

 a short time, because of the complaints against the disagreeable 

 odor of the water.* 



' Recent experiments would indicate that the disagreeable odor was in 

 reality due to irregularities in dosing the water at certain times of the day. 

 There is good reason to believe, however, that during the hours the samples 

 for the series of experiments here enumerated were taken chlorination 

 proceeded with regularity and at the rates recorded. 



