1391.] 35 [Bache. 



we cannot electrolize successfully a large reservoir of water, for in 

 that the electricity would be too diffused to be effective. It is true 

 that, in pipes from which water is flowing into or out of the reser- 

 voir, its germs would not be subjected to attack for more than a 

 second. It is true that the resistance that we should have to over- 

 come in water would be large. But, on the other hand, it is also 

 true that the electric current that we have at our command is 

 capable of indefinite increase. The electro-motive force of a few 

 thousand volts (there are dynamos that generate ten thousand) 

 thrown athwart a pipe of proper dimensions, would probably 

 paralyze every bacterium in its path, more than compensating by 

 force for slight duration in time as compared with the ten min- 

 utes adopted in the experiments of Dr. Griffiths, as to which it 

 is imperative to remember that they did not determine either the 

 amount of current, or of time required, for the destruction of 

 the bacteria experimented upon; and, consequently, it will be 

 observed, both force and time needed are probably very much 

 less than his experiments on their face apparently demonstrate. 

 If lines of water-delivery as well as those of water-supply 

 were subjected to the attack of the electric current, the severity 

 of it would be more than doubled for the organisms. It would 

 be immeasurably increased in severity ; for experiments at the 

 very beginning of bacteriological investigation clearly showed 

 that the best mode of destroying bacteria involves the principle 

 of repeating relatively moderate attacks upon them at intervals 

 such as find them partially recuperated, and assail them in this 

 the period of their least resistant vitality. The method to whieh 

 I allude is that of repeated boiling of slight duration at moderate 

 intervals of time. That they can bear this apparently severe 

 process at all shows the protective influence for them of any 

 fluid immersion within the chemical character that does not 

 wholly ignore the difference of habits among their different 

 species, and water seems to be a medium inclusive of them all, 

 The principle, involved in the mode of attack mentioned is the 

 same as that involved in the mode of destroying bacteria here 

 suggested. Taking it in connection with the facts that a reser- 

 voir represents a large volume of water, only a part or a few 

 parts of which are being momently drawn upon for supply, and 

 that many germs are constantly passing through natural phases 

 of relatively less vitality, infinitely below that in which they, it' 



