1 84 ADDENDUM 



Pearce and Sutherland 1 studied the bacterial content of the 

 water of the swimming bath at Batley (Yorkshire). The first- 

 class swimming bath examined after being used for three days 

 contained on one occasion 2400 2850 organisms per c.c. and on 

 another 219,000 per c.c. The second class bath water after three 

 days gave 15,000 to 17,000 organisms per c.c. on one occasion 

 (with 767 users) and on another 300,000 per c.c. (with 974 users, 

 mostly elementary school children). 



Atkins 2 carried out a long series of studies of the water in 

 the swimming tank of the University of Chicago. The tank 

 holds about 91,000 gallons The examinations were extended 

 over a period of about two months (November and December), 

 during which time the bath was in daily use (Sundays excepted) 

 by about 100 people. Twice a week the water was completely 

 drawn off and the bath refilled with city water passed first 

 through a Jewel filter, using alum as a coagulant. The water 

 was raised to 76 80 F. by steam. 



The entering water contained 250 700 per c.c. on gelatine 

 plates and about 100 125 organisms per c.c. on agar plates. By 

 the end of the first day the counts were in one series 192,000 (gela- 

 tine), 1 64,000 (agar) and in another series 47,000 (gelatine), 45,000 

 (agar). By the end of the second day in the first series they had 

 risen to 625,000 (gelatine), 500,000 (agar), and in the second to 

 510,000 (gelatine), 300,000 (agar). In the second series counts 

 were also made at the end of the third day and showed 500,000 

 (gelatine) and 200,000 (agar). Atkins remarks that this reduction 

 in numbers on the third day is in accord with other observers. 



The B. coli results showed that the water before use contained 

 about 100 B. coli per litre, at the end of the first day of use about 

 200, and at the end of the second day nearly 1000 per litre 

 and about the same at the end of the third day. 



Atkins found no parallel between the rise in the total 

 number of bacteria and the increase in the number of B. coli. 



A number of experiments have been carried out to test 

 the efficiency of disinfectants to purify the water. Of these 



1 Lancet, Aug. 1910, n, p. 542. 



2 Proceedings of the yd meeting of the Illinois Water Supply Association. Feb. 

 1911. 



