IOWA ACADEMY OF SCIENCES. 67 



The standards as given by Masonf for chlorine are as 

 follows: 



Rain 8.22 



Upland surface 11.3 



Deep well 51.1 



Spring 24.9 



Wanklyn considers 140 as possibly suspicious. 

 Frankland considers the permissible limit as 50. 

 Leed's standard for American rivers, 3 to 10. 

 Ordinary sewage, about 110 to 160. 

 Human urine (average of 24 samples), 5872. 



It will be noticed that the standard for deep wells, 51.1 

 parts per million cannot be applied to the deep well waters 

 of this section, and any standard is of little value as far as 

 it relates to the chlorine that is present in the water, how- 

 ever useful the standard for this substance may be for 

 shallow wells. 



The solids on evaporation in the examination of shallow 

 wells is a determination of ^reat value, although the loss 

 on ignition has lost much of its supposed value. In con- 

 nection with the examination of deep well water, how- 

 ever, its chief value may be said to serve simply as a guide 

 to the total substances present in the water, the nature of 

 which can only be determined by a mineral analysis. The 

 various standards which have been proposed for the solids on 

 evaporation cannot be applied to the deep well water or 

 to the mineral waters. For example the standards which 

 have been selected by Mason,* are as follows. 



Rain water 29 . 5 



Upland surface 96.7 



Deep well 432 . 8 



Spring 282.0 



To be condemned 1000. 



American rivers 150. to 200. 



Wanklyn regards as permissible 575 . 



Many of the deep well waters will come within the 

 limits for solids as a few of the solids contained less than 

 600 parts per million. On the other hand many of the 

 results show that the solids are in excess of 1,000 parts per 



i-Wator Supply, p. 374. 

 •Water Supply, p. 363. 



