202 STATE BOARD OF AGRICULTURE. 



There seems to be no constant relationship between the hydrogen-ion concen- 

 tration of water and its oxygen consuming power. In the case of the well 

 water the hydrogen-ion concentration decreases more than in the river water 

 although the latter has the greater oxygen consuming power. This can be 

 explained upon the basis of the greater buffer action of the river water due 

 to the larger amount of organic matter present. The decomposition of the 

 materials present in the water tested had a tendency to make the water more 

 alkaline. This also might be due to the driving off of CO2 and the breaking 

 down of acid salts into alkaline salts. Previous chemical examination of 

 water from the same sources would indicate that this might be the case (3) . 



Conclusions. — 1. The hydrogen-ion concentration of the water decreases 

 upon standing. 



2. The oxj'gen consuming power first increased then decreased. 



3. The bacterial count first increased then decreased. 



4. There seems to be no relationship between the hydrogen-ion concen- 

 tration and the oxygen consuming power of water. 



5. A relationship does seem to exist between the number of bacteria 

 present and the oxygen consuming power of water. 



References. — (1) Standard Methods of Water Analysis. (1920.) 



(2) Clark and Lubs (1917), The Colorimetric determination of hydro- 

 gen-ion concentration of bacteriological culture media. Journal of Bacteri- 

 ology, Vol. 11, Nos. 1, 2 and 3, pp. 1-34; pp. 109-136; pp. 191-236. 



(3) Fabian and Ruehle (1920), Titration of Culture media. Report of 

 Bacteriologist, Michigan Experim^ent Station. [F. W. Fabian and W. L. 

 Mallmann.] 



Professor Mallmann is not officially on the Station staff but he has for 

 several years assumed certain responsibilities that properly rest on the 

 Station workers. 



REPORT OF MR. W. L. MALLMANN 



Residents of the State have submitted 69 samples of water to this labora- 

 tory for examination during the past year. As in previous years, the greater 

 share of these samples comes from rural districts. The percentage of samples 

 condemned is less than in previous years, but this does not indicate neces- 

 sarily an improvement in rural supplies. The number of samples examined 

 is far too small to permit one to draw any such conclusions. 



The College swimming pool has been examined almost daity, while in use. 

 Seventy-three samples were examined during the school year. The bacterial 

 counts have been somewhat higher during the past year, which I believe is 

 due to the fact that the filter has not been working satisfactorily. 



The method of disinfecting the water is also very unsatisfactory' and should 

 be supplanted by the use of liquid chlorine which, I believe, is a very effective 

 method. The present method of dragging a cheese cloth bag of chlorinated 

 lime through the water keeps the bacterial count down but is a very crude 

 method of treatment. 



