278 PURIFICATION OF PUBLIC WATER SUPPLIES. 



and in this country. One, in this conntry, attempted to 

 charge the water with oxide of iron by the electrolysis 

 of that metal. None of these, however, have as yet ad- 

 vanced beyond the experimental stage. 



One effort recently made, however, is so unique as to 

 justify a brief description. The principle of action is the 

 destruction of the bacteria and their subsequent pre- 

 cipitation. The water is made to pass transversely 

 through a small, short cylinder, in the axis of which are 

 two electrodes approaching nearly. A current of high 

 voltage is passed through the electrodes and the water is 

 so directed as to pass between them. Tli§ shock is sup- 

 posed to destroy every atom of bacterial life. After 

 leaving this cylinder the water is passed through three 

 chambers, in each of which are a number of carbon plates 

 connected with a powerful battery located on its top, the 

 carbon plates being placed vertically near the top of the 

 chambers. Electric terminals are connected to each side 

 of each chamber below its center. A powerful current is 

 passed through the battery and at the same time through 

 the sides of the chambers. A magnetic field is thus in- 

 duced in which the vibratory impulses are at right angles 

 to each other and the molecules of water in passing 

 through this field are dissociated and freed from all ex- 

 traneous matter, which is thrown down, the effluent water 

 being purified. I visited this experimental^ plant in 

 Brooklyn, last summer, at the urgent request of the in- 

 ventor and saw it in operation; but there were no appli- 

 ances at hand for even the simplest comparison between 

 the applied and effluent water. The appearance of the 

 former was good enough, and that of the latter was cer- 

 tainly none the worse. The only chemical analysis 

 shown me indicated a slight increase of " organic and 

 volatile matter" by the treatment; the figures in narts 

 per 100,000 being before treatment B.8, after treatment 

 4.0; mineral matter, non-volatile was reduced, being be- 



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