XI, A. 3 Heise and Aguilar: Purification of Swimming Pools 121 



of the week, as shown in Table XV and fig. 2. The comparison 

 was made only for tank I, as this is the installation on which the 



Table XV. — Variation in quality of water, compared with number of 

 bathers. Tank I. 



Week. 



Series 

 No. a 



Average 

 daily at- 

 tendance. 



Oxygen 



con- 

 sumption 

 (parts 

 per 

 million) . * 



First — — 



Second 



Third . 



4 

 5 

 6 

 2 

 3 

 1 



70 

 37 

 49 

 39 

 43 

 33 



1.34 

 ■ 0.98 

 1.32 

 1.11 

 1.17 

 0.95 



Fourth- ... — - - - 



Fifth 



Sixth 





» As given in Tables II to VII. 



*> Average of readings of last two days. 



most reliable data concerning the number of bathers were 

 obtained. 



Weeks. 



a ^ 



M- 

 0.6- 

 OA- 



os- 



, 





















1 















o. 











^^ 



^-5. 



^--^^ 























~^1 



>^ 



c 



dS"-' 











1 



^ower 







>^ 



-., 







SO 

 40 

 30 







\ 



h 



^ 



^ 



^^ 



-^ 







Undo^ 



1££^ 



^ 





**•< 









^ 



■^ 













y — * 









^^ 



-^ 



► 





































































































" 



Fig. 2. Relation between oxygen consumption and number of bathers. 



Therefore we may conclude that the most significant simple 

 tests on the waters of swimming pools, in addition to the bac- 

 teriological examinations, are the determinations of available 

 chlorine and of chlorine-consuming capacity. Once the quality of 

 the water with respect to its chlorine-binding power has been 

 established, it should be an easy matter properly to regulate the 

 dosage. The qualitative test for chlorine is then enough for 

 control purposes, as it shows whether a sufficient concentra- 

 tion of chlorine is being maintained and indicates any sud- 

 den variations which might be caused by occasional abnormal 

 contaminations. 



