126 Drinking- Water and some of its Impurities, 



contaminated with the typhoid poison, after more than a 

 mile of thorough percolation under ground, was still viru- 

 lent enough to carry sickuess and death to a whole com- 

 munity. 



Thus it will be seen that a spurious importance has been 

 assigned to the presence of organic compounds in water, 

 and that the great and all important question is, how to 

 secure absolute safety against any contamination from the 

 excreta of persons suffering from malignant zymotic 

 diseases. So long as sewage is poured into the source of 

 drinking-water there is imminent danger to those using it, 

 unless the conditions are such as to insure the de- 

 struction of the poison. 



It is a matter of very little comparative consequence 

 whether one drinks water containing algales which may 

 look unpleasantly or even smell disagreeably, but water of 

 apparently greatest purity, in which neither chemical 

 analysis nor microscopic examination reveals the presence 

 of danger, may yet be the medium for transmitting a 

 deadly poison. 



