320 



Water and its Impurities, with 



pure in the city. During the summer there are intermis- 

 sions in the bad odors, and they occur at these times. 

 When it becomes clear in the lake the growth again 

 springs up, and the whole derangement is renewed. 

 The sulphur and phosphorus smells intervene, and be- 

 come more or less mixed with the other, for the animalcula 

 grow and die with the alternations of gases in the water. 



I should like to examine more fully some matters which 

 are suggested by what we have been considering, but the 

 urgency of other duties, and the length of this paper, 

 already longer than was originally intended, forbids. The 

 following conclusions present themselves. 



The water would be pure if the organic matters were 

 killed before they entered Bleecker reservoir so that they 

 would assume the character of mechanical impurities in it 

 in a state of decay. This might be done by bringing it 

 through a large number of small iron pipes from one lake 

 to the other. Such a remedy, however interesting in a 

 scientific point of view is not to be considered for a moment 

 as a practical one, for the only practical remedy is to pre- 

 vent any of the contaminations from occurring. 



This will be done when the water is not allowed to 

 become stagnant. 



The plan of introducing a larger supply is agitated 

 by the water authorities; a small addition will not be 

 sufficient ; it must be enough more to keep a constant 

 current in a lake as large as the Rensselaer, and it is the size 

 of this which offers a serious impediment to the plan. "WJien 

 it was smaller, where there was no lake, the natural current 

 of the stream no larger a stream then than it is now was 

 sufficient. But when it was dammed up there was not 

 current enough in it to sufficiently agitate so large a body. 

 If it were possible to reduce the size of the lake in sum- 

 mer, the present supply might keep it pure : but the 

 consumption is so near the amount furnished that this 



