CONTENTS. 



Page. 



Introduction 1 9 



Microscopical examination of drinking water 9 



Wide distribution of trouble caused by algse in water supplies 10 



Methods in use for preventing bad effects due to algse 13 



Desirability of other methods 14 



Determination of a physiological method 15 



Effect of copper sulphate 15 



Method of applying copper sulphate 25 



Practical tests of the method 26 



Water-cress beds 26 



Water reservoirs 27 



Effect of copper upon pathogenic bacteria 28 



Typhoid 28 



Asiatic cholera . '. 34 



Comparison of effect of other disinfectants 36 



Colloidal solutions 36 



Conclusions 40 



Necessity of knowledge of organism and condition in reservoir 40 



Application of method for destruction of pathogenic bacteria not designed 



to replace efficient means of filtration already in use 41 



Medicinal use 42 



Conditions under which the Department of Agriculture can furnish infor- 

 mation and assistance in applying this method 42 



Cost 43 



Summary 43 



7 



