Chemical and Physical Papers. 67 



in the bottom on the right bank of the Kansas river, a short 

 distance above the city. 



N. in — S. B. point. Middle point. New pipe. City mains. 



Free ammonia 2.22 2.35 2.23 0.162 



Albuminoid ammonia 0.540 0.452 0.540 0.258 



Nitrites trace none none 0.017 



Niti-ates none none none 0.560 



Bacteria * none none trace present 



This water is pumped from the ground to the top of an in- 

 clined platform from which it falls over riffles into a basin. 

 After being allowed to settle, it is run into another basin, 

 from which the water is pumped into the city mains. 



When first pumped the water is clear, but as soon as it is 

 exposed to the air some of the gases escape, and some oxida- 

 tion takes place, so that a large quantity of iron is precipita- 

 ted, and the water becomes very turbid. The process of oxi- 

 dation continues to some extent in the city mains, but even 

 then the iron is not all precipitated, so that it frequently be- 

 comes turbid after being drawn from the faucet. 



The organic matter of the soil has evidently yielded am- 

 monia as a product of reduction. This may have been brought 

 about by some vegetable organisms like the well-known Cren- 

 othrix, F, which contains iron as one of its necessary constit- 

 uents. When the water has a chance to become aerated, most 

 of the free ammonia escapes. The albuminoid ammonia re- 

 tained is also small. There were no nitrates or nitrites in the 

 freshly-drawn water, but it is evident that some of the am- 

 monia has oxidized to these two bodies, hence we find them 

 in the city water. We have noticed that with this particular 

 water the amount of nitrogen as nitrates found can be used 

 an index of the thoroughness of the aeration at the plant. 



There were no indications of bacterial contamination except 

 in the case of the city water, and here during the past summer, 

 and possibly at the present time, some river water has been 

 pumped into the pipes, as the ground supply was not abundant 

 enough. Of course it may be possible that the nitrates and 

 nitrites came from the river water, but that is not probable, 

 as the analysis has usually shown but a very small quantity 

 of these in the river. 



Water from the points does not show the presence of Colon 



bacillus, while the river water and the city supply do show it, 



■ ? 



* Later, tlie city water when obtained entirely from ground-water was free from 

 bacterial contamination. 



