40 METHOD OF DESTROYING ALGJ3 IN WATER SUPPLIES. 



CONCLUSIONS. 



It is believed that the foregoing experiments demonstrate the possi- 

 bility of the use of copper sulphate for the destruction or prevention 

 of growths of algae in water supplies, and that when used under the 

 direction of a competent authority, it is the only practicable remedy 

 for this trouble capable of universal application which has ever been 

 proposed. It is, of course, probable that with the experience which 

 must come from a wider opportunity for testing this salt, many 

 improvements will be made in the practical application of the treat- 

 ment to large bodies of water. However, it is hoped that the results 

 already obtained, together with trials now under way, will make it 

 possible to begin using this method within a short time upon a large 

 scale throughout the country. 



NECESSITY OF KNOWLEDGE OF ORGANISM AND CONDITION IN 



RESERVOIR. 



It can not be too strongly emphasized, however, that harmless as 

 the method undoubtedly is under proper control, it must always require 

 a certain amount of definite knowledge in regard to the condition of 

 the reservoir before any treatment can be made, even by those 

 thoroughly able to conduct such an experiment. This is regarded as 

 a fortunate requisite, since it will tend to prevent the irresponsible or 

 careless dosing of reservoirs by incompetents, who are occasionally in 

 charge of water supplies. 



Before the amount of copper to be added can possibly be known, it 

 is absolutely necessary to ascertain the exact character of the organ- 

 ism causing the trouble. This will make a microscopical examination 

 of the first importance. Also, the sooner such an examination reveals 

 the presence of the polluting form, the more effective will be the treat- 

 ment. If examinations are made at short intervals during the entire 

 year, it is possible to detect the troublesome forms at their first appear- 

 ance and by prompt treatment to destroy the algae before the consumer 

 is aware of any difficulty. The early detection of the algse will also 

 make a considerable difference in the expense of the treatment, as it 

 may require fifteen or twenty times as much copper to clean a reser- 

 voir after the bad odor and taste are evident than it would could the 

 application have been made before the organism began to rapidly 

 multiply. In all cases the use of copper as a preventive rather than 

 a cure is advocated, and this can not be intelligently applied unless 

 the microscopical examinations are thorough and frequent at the time 

 of year the trouble is to be anticipated. 



On account of the necessity of determining the nature of the organ- 

 ism and the time of its appearance as nearly as possible, it will become 

 as imperative for water companies to employ some one competent to 



