264 
IOWA ACADEMY OF SCIENCE Voi,. XXVII, 1920 
been that, while the filters are running, the use of copper sulphate 
has apparently given the least satisfactory results. Personally I 
am inclined to think that copper sulphate plus chlorine is most 
satisfactory. We have obtained good results with copper sulphate 
plus calcium hypochlorite, however. 
As has been noted by others in other localities we find that the 
numbers of bacteria in the women’s pool tend to be higher than 
in men’s pool. This is probably due in part at least do the suits 
worn. The fact that the women’s pool is kept at a temperature 
about six degrees higher than the men’s pool may also be a factor 
in favoring the tendency to higher 37° C. bacterial counts. Here, 
however, the bathing load at the men’s pool is greater than at the 
women’s pool and the occurence of gas-forming organisms is more 
frequent. 
In conclusion, the writer wishes to acknowledge the work of 
Mr. Deloss H. Barber, Mr. Frank Kennan, Mr. Cecil E. Ewen, 
and Mr. Roy M. Mayne, who have operated the filter plants and 
made most of the examinations of the pool waters. He also 
wishes to acknowledge the work of Miss Zelma Zentmire, who 
supervised the operation of the pools during the period he spent 
in the Army. 
Eaboratoriks for the State Board of Health, 
State University of Iowa. 
