l899-'00 TRANSACTIONS 147 



It is noteworthy that the increase in chlorine corresponds to 

 an increase in depth, if we omit numbers 6, 8 and 9 in this list. 

 No. 6 is in a hotel yard, and the well is not properly protected — 

 No. 8 is 25 years old, has no pump, and shows every sign of 

 neglect in its surroundings, and No. 9 is 18 years old, not pro- 

 tected from soakage, and dug in soil which has been used as a 

 garden and otherwise from immemorable time. 



I have made, at different times, similar collections of well- 

 water samples near Peterboro, near Hamilton, and at several 

 places nearer Ottawa. The analytical data have a special 

 interest for the neighborhood in question ; but for such a general 

 study as we are now making, it seems scarcely worth while to 

 quote them. They emphasize the point to which I have already 

 drawn your attention, viz. — the difficulty of ascertaining the 

 true chlorine value of normal ground-water. If any considerable 

 number of properly protected wells existed in a given locality, 

 there would be no difficulty about this matter, or at least, the 

 difficulty would be much lessened. A moment's thought will 

 shew you why I speak so guardedly. The chlorine of sewage 

 persists, even after the dangerous character of the sewage has 

 disappeared ; so^hat a properly protected well, dug in a soil 

 which is saturated with sewage, may contain water which is safe 

 in domestic use, for,^ although it contain the chlorine which the 

 sewage contained, the truly dangerous organic matter of the 

 sewage has been destroyed by soil filtration, ..and is now harm- 

 less. The chlorine now points to " past sewage pollution." I 

 think that most of us would prefer that the sewage pollution of 

 the water we drink should be a long time past. I am only 

 mentioning this feature of protected wells here for the purpose 

 of pointing out that the chlorine number of such a well may be 

 much higher than that of the normal ground-water of the 

 locality, and that it would be unsafe to deduce the normal 

 number from it. It is quite true that two wells may be dug side 

 b side, and 'heir water give the same chlorine number, yet one 

 of them may be safe and the other unsafe in use. This only 

 shews that a final decision must not be reached from the con- 

 sideration of any single feature ; but that the history of the well 

 should be studied as fully as possible. Every farmer who digs 

 his own well must be in possession of the needed facts ; and the 

 person who uses a well, with whose history and character he is 

 unacquainted, is as foolish as he would be who should pick up a 



