with oxygen on each date. None of the samples taken in the lake showed 

 any evidence of contamination by river water. In each case the water 

 was more than 90 per cent saturated, 



Osburn (1926a) reported data on oxygen and pH at foiar stations 

 in this area of the lake. Oxygen was high at all stations except the 

 one three-eights mile from the river. Here the bottom water was 

 76 per cent saturated. The pH at these stations ranged from 7,8 to 8,2, 



Chloride and nitrogen 



Samples were taken at a number of stations in the River Raisin 

 Section, Station 117, two miles off the mouth of River Raisin, was 

 visited five times, as shown in Table 39. 



One of the outstanding features of the data is the wide range 

 between the lowest and highest values. This is particularly true of the 

 chloride content, which ranged from 11, Ii to 20,0 parts per million. 

 This range is unexpectedly great, in view of the distance of the station 

 from the river, and the small discharge of the river. Some of the 

 forms of nitrogen also showed a wide range, but this is not surprising, 

 because of the biochemical processes vjhich go on continually. The means 

 of the nitrogen determinations were very much like those at Station 2$i;, 

 in the Maumee Bay Section. These two stations also were much alike in 

 the abundance of phyto plank ton. 



In addition to Station 117, several stations nearer River Raisin 

 were visited (Table iiO), The data are arranged by dates in order to 

 facilitate comparison of the results at different stations. The table 

 includes data from Station 117 on three dates. The results in Table UO 

 show some peculiarities for which explanations cannot be made on the 

 basis of available information. Conditions in this area are highly 

 changeable, and it would be necessary to make a much more detailed study 

 in order to gain a knowledge of the situation with any degree of com- 

 pleteness. But inadequate as t he data are, they have some features worthy 

 of attention. 



As at Station 117, there was a wide range in chloride content at 

 the mouth of the river and at nearby points on different dates. On 

 July 30, August 8, and August I6, chloride was low, while on August 30 and 

 September 11 it was high. In itself this is not surprising because of the 

 reversing current of the river, but it is siu-prising that all stations on 

 a single date had about the same chloride content. Thus on August 8 and 

 16 the current was out of the river, yet the differences in chloride con- 

 tent at the different stations were very small. Table 36 shows that the 

 oxygen content of the water at Station 200 was reduced, which indicates 

 that the water was at least in part river water, and not entirely lake 

 water which had recently-entered the river. On August 30 the current was 



117 



