122 Lily Bell Sefton 



Leffman says: ''The popular notion that hard waters conduce 

 to the formation of urinary calcuU is not borne out either by sta- 

 tistics or by surgical experience .... No absolute maxi- 

 mum or minimum can be assigned as the limit of safety."^ The 

 table below shows that the amounts ran from 28 to 807 parts, 

 the difference being due largely to the difference in the deposits 

 through which the waters have come. 



Since chlorides are abundantly distributed in the soil and are 

 in most cases freely soluble, a wide range of amounts may be 

 looked for. But one sample (14) runs higher than 20.12 parts. 

 Phosphates, on the other hand, while just as freely distributed 

 as chlorides, are highly insoluble, so that we may expect, what 

 we really find to be the case in this particular instance, very 

 little, if any traces of phosphates. Both chlorides and phosphates 

 are characteristic of animal excretions, hence an excessive amount 

 of either or both with no apparent reason, is open to suspicion. 



Mention has already been made of the oxygen-consuming 

 power. The estimation of this gave much trouble, until abso- 

 lutely ammonium-free water w^as finally used as a standard. 

 Each sample and the standard was treated with acidified potas- 

 sium permanganate and kept at a temperature of 96° C. for three 

 hours. At the end of this time, by titrating with sodium thio- 

 sulphate, it was found how much oxygen had been consumed 

 by the organic substances in the water. In but three of the sam- 

 ples was an excessive amount consumed. Samples 4 and 22 have 

 already been satisfactorily accounted for, and sample 10 does 

 not exceed the maximum limit according to Leffman.^ 



* Ibid., p. 92. 



* Ibid., p. 99. 



