68 The Philippine Journal of Science laie 



of disinfectant necessary for efficient purification, time required 

 for sterilization, or duration of bactericidal effect is due to the 

 influence of one or more of these factors. Quality of water, 

 the amount of disinfectant, decomposition rate of the disinfect- 

 ant, temperature, illumination of the pool, period of time water 

 was in use, extent to which bacteria have gravitated to the 

 bottom, manner of cleaning tank, wind, and other factors modify 

 the biological conditions. Heise ^^ has shown that an addition 

 of calcium hypochlorite equivalent to 1 part of available chlorine 

 per million parts of the water used in the Manila swimming 

 pools is reduced in two hours to about 0.1 part. 



The bactericidal value of chlorine is reduced " by the chlorine- 

 consuming power of various substances with which it may 

 come in contact. Thus Heise " found that on adding bleaching 

 powder equivalent to 32 parts of chlorine per million parts of 

 water and allowing it to act two hours in diffused daylight at 

 28°C. the amount consumed was: 



Parts. 

 In distilled water 0.75 



In city water (unchlorinated) 1 to 2.5 



In 200 cc. distilled water +0.5 cc. saliva 10.0 



In 200 cc. distilled water +0.5 cc. sweat 28.0 



In 200 cc. distilled water +1.0 cc. urine 23.5 



The preceding data show that the contamination of a pool by 

 substances such as the secretions and excretions of the human 

 body should be avoided so far as possible, not only because such 

 materials carry bacterial flora with them and in themselves often 

 furnish food material for microoganisms, but also because they 

 actually reduce the amount of available chlorine. 



POOLS TESTED IN PRESENT WORK 



Tests of the bacterial condition of swimming pools have 

 usually been made in temperate zones. On account of the special 

 conditions met with in the tropics, it seemed advisable to make 

 tests on the three swimming pools of Manila. These pools will 

 be designated by the numerals I, II, and III. Pools I and II 

 were made of concrete and were inclosed on the sides. Pool 

 III was lined with glazed tile and was protected by a roof, but was 

 not inclosed on the sides. The size of these tanks is shown in 

 Table A. 



"This Journal, Sec. A (1916), 11, 112. 

 "Glaser, Arch. f. Hyg. (1913), 77, 165. 

 " This Journal, Sec. A (1916), 11, 114. 



