Adenky, Leonard, and Richardson — Aeration of Water. 



25 



JExperiviental Besults. 



The conditions obtaining in some experiments with columns of salt solutions 

 and of distilled water are given in the table on opposite page. 



(/urves showing the nitrogen content of cohimns of distilled water, and of salt 

 solutions, at different depths, expressed as percentages of saturation, are given in 

 fig. 2. 



On comparing the curves D, for distilled water (exposed to the air for 

 twenty-sexen days) and Si, for a o'3 per cent, sa't solution (fourteen days), the 

 effect of the salt on the progress of aeration is well illustrated. The curve for the 

 distilled water column shows a fall in nitrogen content from 40 per cent, at the 

 surface to 13 percent, at a depth of 311 cms., whereas the corresponding values 

 for the 3'3 per cent, salt solution ranged fronr 427 to 38o per cent, respectively 

 in about half the time. 



Depth ill centimetron. 

 Fig. 2. — Nitrogen content expressed in percentages of saturation at different depths below tlie snrface. 



Even with a solution containing only 0-0116 per cent, sodium chloride 

 (curve Ss), the effect of the salt in solution is well marked. 



The curves S/, S/, S/, T, and T, are plotted from results obtained from 

 observations with columns of sea and tap water, 3 feet deep and 4 cms. diameter. 

 The columns were exposed to the air at temperatures 14^', 12^, 13'5°, 1-i^ and 

 13-5' 0. for 7, 6'75, 1 1,4, and 7 days respectively. 



Samples of the salt solutions from the top and bottom layers of the columns, 

 after aeration, were carefully examined by means of a Pulfricb refractometer to 

 ascertain whether any difference in concentration of the soilium chloride exis'.ed 

 between the two layers, but no difference could be detected. 



