Section III., 1914 [133] Trans. R.S.C. 



On Osmosis in Soils. 



(By C. J. Lynde, Professor of Physics, and J. V. Duprc, Research Assistai! I under the 

 Dominion Grant for Agriculture. Macdonald College, P.Q., Canada.) 



(Presented by Prof. H. T. Barnes). 

 (Read May 27, 1914). 



For the sake of clearness we have divided this paper into two 

 parts. 



In part one we describe experiments in which we measured the 

 osmotic pressures obtained when we used a column of very fine soil 

 as a semi-permeable membrane and a concentrated soil solution as the 

 active solution. 



In part two we describe an experiment to determine whether 

 or not the pressures observed were due simply to the swelling of the 

 soil column. 



HISTORICAL. 



It is usually stated that soil water is subject to threee types of 

 movement, namely, gravitational, capillary and thermal. In studying 

 the movement of soil moisture I was gradually led to the conclusion 

 that in producing this movement there is some agency at work, other 

 than those given above. 



In considering what this agency might be I was led to the fol- 

 lowing theory. 



Theory That Soils Act as Semi-Permeable Membranes. 



It is possible: (1) that soils act as semi-permeable membranes; 

 (2) that the greater the depth of the soil the greater is its efficiency 

 as a semi-permeable membrane; (3) that a soil solution moves through 

 the soil by osmotic pressure from points where the solution is less 

 concentrated to points where it is more concentrated. 



In 1912 I read two papers 1 before the American Society of Agro- 

 nomy at their Meeting at Lansing, Mich. The results presented 



1 "Osmosis in Soils," Journal of Physical Chemistry, Vol. 16, No. 9, December, 

 p. 759 (1912). 



