Tlie Water of t}ie Mississippi rirer I)()(lge. 41^ 



we cau couveiiieiitly and without threat expenditure of time or 

 complication of a])paratus apply to a sanitary examination of 

 water, \vonld show a verification of the theory of self-purification 

 of river waters. The result seems to me fairly satisfactory. It is 

 the result of but one trial at the present time. A repetition of 

 these comparative tests carried through the several seasons of the 

 year, would be more completely satisfactory. 



I wish now to make some further reference to that other 

 (question connected with this subject which was mentioned at the 

 bej^inning, tlie question as to the completeness of this process of 

 oxidation and destruction of organic matter which we see go- 

 ing on in our rivers. If we were to place an unqualified reliance 

 upon the results of our chemical tests for the sanitary character 

 of water, we should be obliged to say that the water taken from 

 the river at Winona is purer than that taken at any point above, 

 in our series of analyses; and this, in spite of the fact that the 

 river has received on the way the sew^age of Minneapolis and St. 

 Paul. Even within the short distance between Minneapolis and 

 Hastings, the self-purification of the water appears to be such that 

 the water at Hastings is scarcely more contaminated and in some 

 respects less contaminated, than that above Minneapolis, although 

 the river at St. Paul shows itself highly impure by our tests. 

 Shall we then say that the water at Hastings would be as whole- 

 some and safe for drinking as that above Minneapolis? Is the 

 water at Winona better than that above Minneapolis? In seek- 

 ing to give an answer to these questions, [can hardly do better 

 than quote a few ])aragraphs from Professor Frankland of Lon- 

 d(m. one of the leading chemists of the world, and one who has 

 given a great deal of sj)ecial attention to the sanitary analysis of 

 waters. In speaking of the contamination of water by sewage 

 matters, Professor Frankland says: "The excrementitious matters 

 which exii^t in sewage are sometimes possessed of intensely infec- 

 tious proj)erties; and sewage mixing with water, even in the 

 minutest proportion, is likely by such properties to spread epid- 

 emic diseases among populations which drink the Avater. Thus is 

 explained the peculiar power w^hich impure waters have beeji 

 shown to exercise on many occasions, in promoting epidemics of 

 tyjihoid fever and cholera. The existence of an infectious property 

 in water caiwot t>e proivd t>tf chemical analysis, and is only learned, 

 toolat^, from the effects which the water produces on man. Tint 



