ISSO.] 



Wafer svppJics of Calcutta. 



113 



The following taLle will show the classification of the tank and well waters 

 according to the amounts of chlorine. 



Tank waters, . . . 

 Percentage, ... 



Well waters, . . . 



Percentage of 

 well and tank 

 waters, . . . 



9 < 



66 

 45 



49 

 C4 



flS org 



o y p o 



fe . « 

 £ o/)o d 



,2 a 



38 

 30 



18 

 24 



28 



O a ■ 



:S S -2 



o o 



.2 ^ 



:3 ? 



-t; 'a .t: 1^ 

 o c3 m .rt 1 



14 



11 



o -fi o 



ci . ^ ^ f-H 



> ofi :C CD 



o ^ 



nj O 



^ '^1 . 



C5 



It would of course be quite permissible to consider waters which have 

 been condemned by either of these two methods to be sewages, dilute 

 sewages or unfit for domestic use, etc., but on inspection of the tables 

 it will be seen, that as a general rule a water which is condemned by the 

 total ammonia test is also condemned by the amount of chlorine present. 



The results, however, are sufEciently startling, if we only take the 

 mean of the results of the two determinations ; and at the very lowest esti- 

 mate it must be said, that of the 200 samples of Calcutta tank and well 

 waters examined by me, forty-four per cent, were true sewages, twenty-two 

 per cent, were dilute sewages, twentjr per cent, of the waters were contami- 

 nated with considerable quantities of sewage, nine per cent, were " dirty 

 waters," and about four or five per cent, only were moderately safe waters. 

 These last consisted principally of the well kept tanks on the maidan, and 

 two or three others in the southern part of the town. 



In the next table I have grouped the well and tank waters according 

 to the sections of the town to which they belong ; in this table I have 

 given, first the name of each section and its population per acre according 

 to the census of 1876, then the total number of waters analysed from each 

 section, with their classification according to the i)lan before adopted. 

 There is also given the average composition of all the waters analysed in 

 each section. It will be strikingly seen from this table, how much more 

 impure the tanks and wells of the northern divisions are, than those of the 

 southern sections of the town. 



