42 METHOD OF DESTROYING ALG.E IK WATER SUPPLIES. 



reservoir which may have ]>ecome infected with some nonspore- 

 forming- disease germ. Its application to barnyard tanks and pools 

 as a preventive of hog cholera may also prove to be of value. Since 

 the selective toxicity of this salt renders it fatal to pathogenic forms 

 peculiar to water, while the common sapro])hytic or l)eneficial bac- 

 teria are unaffected, the method is particularlv well adapted for this 

 purpose. 



MEDICINAL USE. 



While it is not within the province of this ])ulletin to discuss or 

 recommend any line of medical treatment, reference should be made 

 to the fact that certain eminent practitioners, after reviewing the 

 results here published, are of the opinion that the use of copper in 

 cases of typhoid fever and related diseases should be more thoroughly 

 investigated than it has been heretofore. It was the testimony of sev- 

 eral that other intestinal troubles, more recenth' presumed to be due 

 to the presence of certain disease germs in drinking- water and milk, 

 had responded most favorably to copper in one form or another. 



CONDITIONS UNDER WHICH THE DEPARTMENT OF AGRICULTURE CAN 

 FURNISH INFORMATION AND ASSISTANCE IN APPLYING THIS METHOD. 



The prol)lem of destroying or preventing the growth of alga^ b}- the 

 method devised in the laboratory of plant physiology in water reser- 

 voirs, lakes, ponds, water-cress beds, and wherever these plants have 

 become a pest, is one which distinctly comes within the province of 

 the Department of Agriculture. Definite instructions as to the treat- 

 ment to be followed will at all times be furnished to the proper author- 

 ities who may desire assistance, and in so far as the limited facilities 

 of the laboratory permit, determination will be made of the organisms 

 causing the trouble. It is earnestly hoped that no tests of the method 

 described here will be made without tirst consulting with the Depart- 

 ment. Those most intimately connected with this work are constantl}^ 

 gaining information and experience, and this ma}' prove of consider- 

 able value, besides a saving- of expense, to those who have occasion to 

 exterminate algal pests. 



The treatment of water supplies for the destruction of pathogenic 

 bacteria, or any application of the copper-sulphate method which has 

 to do with public health, is not contemplated or indeed possible by this 

 Department. The requests of private individuals or unauthorized 

 bodies for information or assistance can not be granted. When State 

 or local boards of health consider that the disinfection of a water sup- 

 ply is desirable and wish information upon the subject it will be 

 supplied as fully and freely as possible. All experiments of this kind, 

 however, must be conducted by the board of health, and the Depart- 

 ment can serve only in the capacity of an adviser. 



