58 



and the odor becomes quite strong. This, of course, is what occurs when the 

 water runs into the service pipes. The change of conditions causes the disrup- 

 tion of the colonies, and so we get the smell and taste in the hydrant water, but 

 almost none in the water examined fresh from the reservoir. 



This matter of the cause of such odors and tastes in drinking waters has been 

 the subject of much study by the Massachusetts Stnte Board of Health i, and I 

 had the privilege of doing some work in that line in 1894, while connected with 

 that Board. Most of the experiments were conducted on this Uroglena because 

 it had such a strong and characteristic odor. Large quantities of water contain- 

 ing an abundance of Uroglena were filtered through cotton, and this cotton was 

 immersed in ether and several other solvents of oil, particularly the volatile ones. 

 Then the ether was allowed to evaporate, leaving an oily residue on the watch 

 glasses which in some cases gave the characteristic odor, somewhat intensified. 

 But in nearly all of the experiments trouble was caused by the ether itself leav- 

 ing a noticeable residuary odor after evaporation, which was in some instances 

 quite misleading. The Uroglena oil, however, was collected, and did to a certain 

 extent have the sought for odor. Among the other solvents tried were carbon 

 bisulphide and chloroform, with the same difficulty of the residuary odor. 



The ordinary method of microscopical analysis (Sedgwick-Rafter) is practi- 

 cally useless in determining the numbers of Uroglena colonies in a given quantity 

 of water, because of the readiness with which the organisms break up. The esti- 

 mates consequently in such cases would be far too low. In the analysis of the 

 water supply of Lafayette made last October the water was examined without 

 making any attempt to concentrate the organisms. Cubic centimeter after cubic 

 centimeter Avas examined directly with a small band lens, and in no case were 

 there more than twenty colonies per 100 cubic centimeters. The average was six 

 per 100 c. c, but this was sufficient to give the offensive odor to the water when 

 drawn from the faucet. As was found in other cities, and as we might expect to 

 find in Lafayette, the water drawn from the housetops in the morning, while giving 

 the odor, showed absolutely no Uroglena colonies. 



The question naturally suggests itself, how did the reservoir get planted with 

 this troublesome organism? Of course we can make no definite statement in re- 

 gard to this, but an examination of the reservoir overflow, which forms a more or 

 less stagnant pond just below the reservoir itself, showed a larger number of these 

 Uroglena colonies per 100 cubic centimeters than the reservoir water, and it 



'Odors in Drinking Waters. G. N. Calkins. Mass. State Board of Health, Ann. Re- 

 port, 1892, p.3f.5. 



