[lynde-dupré] 



ON OSMOSIS IN SOILS 



77 



Conclusion. (1) The rate of flow increases with increase of tem- 

 perature. (2) The increase is probably proportional to the increase 

 in fluidity of the water and to the increase in osmotic pressure. 



SEVENTH TEST. HOW DOES THE FLOW VARY WITH CHANGES IN THE 

 CONCENTRATION OF THE SOIL SOLUTION ? 



To determine this, two tubes were set up as in Fig. 2. The 

 tubes were first filled with a strong soil solution and the flow was 

 measured. The tubes were then emptied and filled with the soil 

 solution diluted to one-half and the flow was measured. This was con- 

 tinued until the solution had been diluted to one sixty-fourth of its 

 first strength. The last experiment was made with distilled water 

 in the tubes. The electrical resistance of the solution was taken 

 before and after each experiment. The readings are corrected for 

 changes in temperature during the flow. 



Table 8. 



Giving the Flow in linear centimetres per day and the Resistance of the 

 Soil Solution at the beginning and end of each Experiment. 



Elec. res. of •02N. KCl at 23''C. 350 ohms. 



Conclusions. (1) The flow decreases with decrease in concen- 

 tration of the soil solution. (2) The resistance of the soil solutions is 

 always less at the end of an experiment than at the beginning. This 

 indicates that the water moves through the soil towards the solution 

 and in so doing carries soluble salts from the soil to the solution. 



