BAD ODORS IN BESERVOIRED WATER. 471 



producing a magnificent fountain, which is visible from all elevated 

 points throughout the city. By this means the whole body of water 

 is thoroughly aerated before it enters the distributing mains." 



The investigation, which consisted of chemical analysis and micro- 

 scopical examination, began December 14th. Samples of water were 

 taken from Hemlock Lake, from the chief storage-reservoir, and from 

 the city mains. The analysis, which was conducted with great care, 

 indicated remarkable purity of the water. It should, however, be 

 noted that earlier experiments might have shown a diiferent result. 

 The microscopical investigation was also conducted with scrupulous 

 care, and with such precautions as to preclude the possibility of the 

 escape of any important organism. The total quantity of foreign 

 matter obtained was in each case surprisingly small " a thousand 

 gallons of water yielding not more than one or two grains of residue, 

 a large proportion of which consisted of minute particles of clay and 

 sand," The facts obtained regarding the fish-like odor were of curious 

 interest. The samples of water taken from the lake and from the 

 reservoirs were found to be entirely free from unpleasant odor, while 

 the fish-like peculiarity was plainly perceptible in the water drawn 

 from the main just before it entered the Mount Hope Reservoir. The 

 odor increased in intensity the farther the water flowed through 

 these mains ; so that, in the northern portions of the city, it was 

 very offensive. It is noteworthy that all the water which reached the 

 city had passed through not less than four wire screens with meslies 

 a quarter of an inch in diameter, and in no case had a service-pipe 

 been known to be obstructed by any portion of the body of a fish. 

 " In filtering many thousands of gallons of water, at different times, 

 and under such conditions as to arrest multitudes of the minutest 

 organisms, not the smallest fragment of a bone, or fin, or scale, of a 

 fish parts which would longest resist decomposition, and float away 

 in the water has ever been detected." 



In answer to the question, " What cause, then, can be assigned for 

 this most peculiar odor?" Prof. Lattimore asserts that it must be 

 due to the decomposition of some form of fresh-water algse. He 

 draws his conclusions partly from the investigations of others, and 

 partly from his own observation and experiment. After the dis- 

 appearance of the odor from the water, he observed that microscopic 

 algae, which had collected on the filters through which water had 

 been flowing for twenty-four hours, exhaled an odor strikingly like 

 that given off by a blade of early spring grass, when crushed by the 

 fingers. A minute quantity of these algoe put into distilled water, and 

 kept covered for a few hours, revealed an odor which was distinctly 

 recognized as that which had recently affected the water from the lake. 



This experiment, with others pointing in the same direction, leads 

 to the conclusion that the fish-like odor must be due to some obscure 

 condition of the algse most likely to their decay and decomposition. 



