'^2fi 



REPOllT — \S7C>. 



This shows that the total amount of nitrogen in the solid mutt«r contained 

 in a sample of sewage or of effluent water is not altered by keeping, provided 

 the bottle be well filled. It is worthy of 'note that the nitrogen in the 

 effluent water was almost all converted into nitrates*. 



In order to ascertain the effect of keeping sewage in unfilled bottles, the 

 following experiments were made. The remnants of the January sewage 

 and effluent water, which had been left in the bottles, were analyzed again 

 on July loth, 1876, and the sewage again on July 31st, and the following 

 results obtained: — • 



It appears, then, that a large quantity of the nitrogen in the sewage was 

 lost between February 1870 and July loth, 187C, while the nitrogen in the 

 effluent water was only slightly diminished in amount, but was almost all 

 oxidized to the condition of nitrates. 



It appeared desirable to ascertain how much of the nitrogen in the sewage 

 was thus oxidized, and a third analysis was therefore made on July Slst, 

 1876, which showed that a still further loss of nitrogen had taken place, so 

 that the total nitrogen which was at first 6-48 parts had been actually re- 

 duced to only 1-52 part per 100,000; and of this 1-52 no less than 1-05 

 part was in the form of nitrates. It is probable that much of the nitrogen 

 thus lost escaped in the free state. 



The total amount of nitrogen received from the town in the sewage wa.s 

 greater than during any previous year, and shows conclusively that the in- 

 creased amount of sewage does not merely depend on the rainfall, which was 

 considerable, but that new connexions with the sewers are being made in 



* The unusually small amount of nitrogen "not nitrates" in the effluent waters in 

 187-1-75 was doubtless partly owing to the fact that the samples were not analyzed until 

 the end of the year. 



