1867.] 



with the supply of water to Calcutta. 



Bate of collection 

 or preparation. 



14th May, 18GG. 



Bate of E.ipt. 



For 100,000^. grains W. 

 Organic matter. Oxygen reqd. 

 Grains. 



Grains. 



Cornwallis Square Tank W. 



5.15 



4.40 



4.37 



15th Scptemher. 



18th September. 



8th August. 



18th September, 

 cleared by- 

 Acid 



.209 

 .155 



.350 



June 



21st May, 

 20th June, 

 11 th August, 

 6th September, 



Baranagar Tank W, 



15th Sept. 

 17th 

 29th 

 *2nd October, 



Dalhousie Square Tank. 



19th Sept. 

 29th 



River Water. 



17th August, 



2.5th Sept. 



18th 



19th 



29th, more than 



The Mixtures were composed of river water of the hot season three 

 or four months old and of recent river water with a little Salt Lake 

 water, No. 3 containing also Tank water ; with these were mixed the 

 specified proportions of sewage water which had been collected on 8th 

 September, and, as tried on the 9th, contained 27.33 grains organic 

 matter in 100,000 fl. grains. 



It will be observed that in the organic matters oxidised by the per- 

 manganate of potash there is a distinct diminution early, even by the 

 lapse of a single clay, as indicated by the smaller quantity of oxygen 



2.38 





2.16 



.256 



K 



.228 



1.59 



.100 



t 1.89 



.070 



1.08 





1.01 







.085 



1.69 



.044 



t 1.36 



.046 



* Introduced after date of paper. 



f Evidently an error of Expt. The organic matter could not increase. 

 % Exp. faulty. Enough of Carb. Soda had not been used. Eesult could not 

 have been less, but probably would have been greater, had it been correcc. 



