CONTENTS. 



Page. 



Introduction ^ 



MicT()w;opical examination of drinking water 9 



Wide distribution of trouble caused by algie in water supplies 10 



Methods in use for preventing bad effects due to alga^ 1-^ 



Desirability of other methods — 1"^ 



Determination < if a physiological method 15 



Effect of copper sulphate ^'^ 



Method of applying copper sulphate 25 



Practical tests of the method 26 



Water-cress beds 26 



Water reservoirs 2/ 



Effect of copper upon pathogenic bacteria 28 



Typhoid - 28 



Asiatic cholera •^■* 



Comparison of effect of other disinfectants 36 



Colloidal solutions 36 



Conclusions - ^^ 



Necessity of knowledge of organism and condition in reservoir 40 



Application of method for destruction of pathogenii; bacteria not designed 



to replace eflacient means of filtration already in use 41 



Medicinal use ^2 



Conditions under which the Department of Agriculture can furnish infor- 

 mation and assistance in applying this method 42 



Cost 43 



Summary - 43 



7 



