1866.] 



with the supply of water to Calcutta. 



233 



Table V. 



For 100,000 fluid 



grains. 





Date of col- 



Solid 



Organic 



Oxygen 



Ammo« 





lecting. 



matter. 



matter. 



reqd. to 



ma. 





1866. 







oxidise. 





General's Tank, 



6 June, 

 14 Aug. 



12.05 



1.35 



.0825 

 .1225 



.235 



Monohur Doss's Tank, 



14 May, 

 6 June, 



24.60 



2.00 



.0913 

 .1000 







14 Aug. 







.1400 



.204 



Dalhousie Square Tank, 



14 May, 



23.85 



1.50 









6 June, 



25.80 





.0750 





Cornwallis Square Tank, 













settled and veg. matter de- 













posited, 



14 May, 



58.00 



4.40 



.1550 





not settled, 



14 Aug. 





5.15 







Dhurrumtollah Tank, 



Aug. 







.2975 



.237 



Barnagore, 



11 May, 

 8 June, 

 17 Aug. 



51.00 



4.25 



.3170 

 .2938 

 .3375 





Dhurrumtollah well, 



Aug. 







.0725 





Barnagore well, 



18 Aug. 







.0900 





Salt Water Lake, 













from Canal at Dhappa Toll 













House, 



13 June, 



908.00 



20.00 



.1250 





Ditch conveying sewerage of 













Calcutta, 



1 June, 



295.80 



33.10 



5.680 





* Ditto, 



8 Sept. 





27.33 







* Ditto, 



13 Sept. 





22.25 







On examining this table, it will be observed that even the best tank 

 water contains more organic matter by weight, and requires more 

 oxygen to oxydise it than does the river water during ebb tide ; even 

 Dalhousie Square water appears to deteriorate by being removed 

 from the running stream into a stagnant reservoir. The excess of 

 organic matter in the bad tanks is also very noticeable. The two 

 well waters require more oxygen than the river water generally. 



* Added since the date of the paper* 



