1880] 



Wafer supplies of Gahulta. 



93 



as the sewage, unless it has been diluted by subsoil water or concentrated 

 by evaporation. 



As an illustration o£ the quantities of total ammonia and of chlorine 

 as chlorides found in samples of good or fairly good drinking water, I may 

 quote some numbers taken partly from Prof. Wanklyn's work on water 

 analysis, and partly from other sources such as the Rivers Pollution Com- 

 missioners' lieiwrts. The numbers given in the following table show the 

 number of parts of total ammonia and of chlorine in every million parts of 

 the water, and the samples of water it will be seen are selected from a variety 



of sources, such as lakes, rivers, wells, springs, &c. 





Total Ammonia 



Chlorine parts 



Desckiption op Watek. 



parts per 



per million 





million of water. 



of water. 



London water, Kent Company, 



0-03 



23 5 



„ ,, New River Company, 



0-08 



15-7 



Glasgow water from Loch Katrine, 



0-08 



7-6 



Edinbui'gh town water. 



0-07 



14-3 



Manchester town water, 



0-07 



9-0 



Chester (Dee) town water, ... 



0-07 



5-0 



Oxton (Birkenhead) town water, 



02 





Guildford water. 



0-01 



12-6 



Caterham water from deep spring. 



0-04 



16-5 



Deep spring- at Dorking, 

 Deep Well at Chatham, 



0-01 





0-06 





As an additional comparison of the quantities of " Total Ammonia" 

 and of Chlorine, which a good potable water should yield, I will quote the 

 amounts of these substances which have been obtained during the last 

 four years from analyses of the Calcutta Hydrant water made twice in 

 each week. In the following table there are given the average results 

 obtained for each of the last four years, as well as the general average for 

 the whole of this period. 



Calcutta Hydrant Water. 





No. of days 

 of Analysis. 



No. of days 



when 

 transparent 



and 

 colorless.* 



No. of days 

 when not 

 perfectly 

 filtered. 



Total 

 ammonia 

 in parts per 

 million.. 



Chlorine 

 in parts per 

 roillion. 



Average 1876, ... 



1877, 



1878, 



1879, 



155 

 104 

 103 

 103 



137 

 72 

 75 

 91 



18 

 32 

 28 

 12 



0-037 

 0-046 

 0-034 

 0-035 



10-65 

 10-40 

 8-37 

 8-50 



Sums, 



465 



375 



90 



0-152 



37-92 



Average, ... 



116 



94 



22 



0-038' 



9-48 



* When cxamiuod by transmitted light in a tubo three feet in length. 



13 



I 



