268 PURIFICATION QF PUBLIC WATER SUPPLIES. 



dent of the Poughkeepsie City Water Works, read the 

 followiug paper on the 



PURIFICATION OF PUBLIC WATER SUPPLIES. 



BY CHAS. E. FOWLER. 



When we speak of the purification of public water 

 supplies clarification is to be understood, as a matter of 

 course, but it is intended to go much farther and remove 

 those substances that are prejudicial to the practical 

 operations of domestic and manufacturing interests and 

 to the health of the community, the latter taking prece- 

 dence. 



The opinion of scientists as to the constituents which 

 render water injurious to health, as well as their 

 methods of detection, Imve ube^^ed Lue couunon law and 

 experienced change with the march of years. 



It is not many years since it was the prevailing opinion 

 that the specific substances contained in water and re- 

 vealed by chemical analysis rendered it injurious, regard- 

 less of their source, or the circumstances of their forma- 

 tion ; hence the careful determination of mineral con- 

 stituents. 



At the present time the effort of the sanitary water 

 analyst, ordinarily, is to determine the origin and condi- 

 tion of the organic matter, and judge therefrom as to the 

 probable presence of those germs of disease which may 

 accompany organic matter, but which cannot be detected 

 by chemical examination, and which constitutes the chief 

 source of danger in ordinary surface waters, such as com- 

 prise the much larger portion of the water supplies of 

 this country. 



It is interesting to compare two chemical analyses of 

 the water of the Hudson river. The first, made by Prof. 

 Farrar, of Vassar College, in 1869, and the other by Prof. 

 Drown, of Mass. Inst, of Technology, in 1893. Both 



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