507 



much quicker, however, as it approaches the rapids at the junction 

 with the Des Plaines. The water was more or less yellow with clay 

 silt. The color, odor, and the organisms obtained, were those of a clean 

 and practically uncontaminated stream. The water temperatures at 

 the surface were 69.7° F. July 24, 72.4° July 26, 82.5° August 9, and 

 73° August 21. 



Nine determinations of oxygen were made on different dates, — 

 July 24 and 26, August 10 (forenoon and afternoon), and August 

 21 (forenoon and afternoon), 191 1; and February 19, September 

 26, and November 14, 191 2. Four tests for carbon dioxide were also 

 made — July 26, August 10, and August 21 (forenoon and afternoon), 

 191 1. Six of the nine oxygen determinations showed that the water 

 was supersaturated, percentages ranging from 104.6, September 26, 

 to 133. 1 on the afternoon of August 10. The lowest result was 

 62.2 per cent, of saturation on February 19. The general average 

 of the nine determinations is 103.8. Forenoon and afternoon tests 

 for the same day were made August 10 ( 10 130 a. m. and 2 130 p. m.) 

 and August 21 (10:30 a. m. and 2 p. m.). Those for the forenoon 

 averaged 101.7 per cent., and those for the afternoon 121. 2 per 

 cent. The afternoon increase was doubtless due to the liberation 

 of oxygen by submerged plants under the influence of sunlight. The 

 carbon dioxide found July 26 was 2.1 parts per million; August 10, 

 .7 parts; and August 21, none. 



The biological conditions were those of a clean stream, there be- 

 ing no plants or animals obtained here in either year commoTily 

 classed as saprol:>ic — no blue-green alg?e, no Carchcsium or other fixed 

 forms of Protozoa, no oligochjete worms, and no Sphccrotilus or 

 Bcggiatoa. Green filamentous alg?e — mostly Cladophora gloinerata, 

 with some Microthamniou and J^auchcria — many river mussels — the 

 greater part of w^hich were, however, for some unknown reason 

 dead — and several water snails (Gouiobasis), were among the com- 

 moner clean-water forms. 



Ilunois River at Morris 



The water here was grayish, sloppy, and everywhere clouded with 

 tufts of Sphccrotilus and Carchcsium. The odor was continuously 

 foul, w^ith a distinct privy smell in the hottest weather. Bubbles of 

 gas were continually breaking at the surface from a soft l^ar of 

 sludge formed along the north bank between Kindlespire's landing 

 and the Mazon bridge. On the warmest days putrescent masses of 

 soft, grayish black, mucky matter, from the diameter of a walnut 

 to that of a milkpan, were floating on the surface. These masses. 



