Reference to the Supply of Large Toicns. 319 



bubbles of the gases it generates in decay, rises to the 

 top, and with the most offensive smell makes either the 

 islands of rotting vegetation, that observers have found, 

 or is driven ashore by light winds. A heavy wind dis- 

 turbing the water to auy extent would disengage the 

 buoyant bubbles and leave it to fall to the bottom, now in 

 its decay being heavier than the liquid in which it floats. 



At this time it partakes of the character of any decom- 

 posing material that might be placed in the lake. The 

 action of the air removes the gases almost as soon as 

 - formed, and, unless at the mouth of a supply pipe, a 

 supply of water is furnished the city purer than just 

 before. A dead animal thrown in the middle of the lake 

 would no more make the water impure than the organic 

 matters in the river affect its. purity, after a short distance. 

 Neither does the excrement of the fish, nor the decay of 

 dead fish ; nor, for the same reasons, would the decaying 

 vegetation produce bad tasting or smelling water. The 

 disgusting odors leave .the water, and float away in the 

 air, which, at this time, according to the united testi- 

 mony of all observers who have reported upon it, is in the 

 most intolerable condition. This fetid atmosphere would 

 prove that the purifying of the liquid was going on, 

 if we had not a perfect illustration of it in the river. 

 "We find this principle illustrated in many familiar ways. 

 Good coffee cannot be obtained by a process of making, 

 which fills the house with its aroma ; all of the many 

 complex contrivances, that have within a few years, 

 become so popular for making coffee which is to retain 

 its flavor, are only so many arrangements for performing 

 the necessary operations, while the volatile oil that gives its 

 flavor is retained in the liquid, instead of being dissipated 

 in the air. 



Therefore, it is at these times, when the first growths 

 are rotting in the lake, that the water is comparatively 



