551 



ADDITIONAL DATA UPON THE RIVER SLUDGES 



Since this manuscript was prepared we have received from the 

 chemists of the Water Survey a report on the following series of nine 

 sludge samples collected in March, 191 3, with a view to determining 

 the winter condition of the ri\'er sediments throughout the length of 

 the stream. It will be seen that they agree in the main with the short 

 series on page 00 to the effect that a marked change occurs between 

 Marseilles and Henry, and that they show a gradual improvement in 

 respect to organic contents in the samples obtained below Peoria. 



