276 puKiFiCATiojsr or public water supplies. 



was said to have been tried at St. Louis, Mo., and to give 

 excellent results. 



Beside being used as above stated, simple a3ration is 

 sometimes used as a method of purification in connection 

 with sedimentation, and sometimes in ordinary distrib^ 

 uting reservoirs. 



Its peculiar function is to drive out the gases arising 

 from the excessive development of certain forms of low 

 plant life, which impart an unpleasant odor or taste to 

 the water, and also to prevent such excessive develop- 

 ment. It is usually accomplished by forcing atmos- 

 pheric air, under pressure, through small openings in 

 pipes laid around, into, or through the reservoir or basin ; 

 and sometimes by means of cascades or other methods of 

 exposure in open air. It has been commonly supposed 

 that the forcible introduction of air into water, or the 

 agitation of water in contact with air, would hasten the 

 oxidation of organic matter contained therein by a pro- 

 cess analogous to combustion. 



Elaborate experiments by both A. R. Leeds and T. M. 

 Drown show conclusively that such is not the case. Dr. 

 Drown sums up the results of a long series of investiga- 

 tions in connection with the Massachusetts State Board 

 of Health as follows: (1) "The oxidation of organic 

 matter in water is not hastened by vigorous agitation 

 with air or air under pressure. (2) The aeration of water 

 may serve a useful purpose by preventing stagnation, by 

 preventing the excessive growth of algae, by removing 

 from water disagreeable gases, and by the oxidation of 

 iron in solution." 



The sewerage of the village of Brewster, N. Y., within 

 the Oroton water shed, discharged into the east branch 

 of the Croton River. There was no land available suit- 

 able for the disposal of this sewage, so a method of 

 electrical treatment, before its discharge into the river, 

 was adopted. This method is known as the"Woolf" 



