Movement of Water and Salt through a Clay‐Water System: Experimental Verification of Onsager Reciprocal Relation

Equations that describe the movement of solution and salt through a soil system in which there are both hydrostatic and osmotic pressure gradients are presented. These equations are: J V = − L P ∇ P + L PD ∇π, J D = L DP ∇ P − L D ∇π, and J S /C S = (− L P + L DP ) ∇ P + (− L D + L PD ) ∇π where J V is the flux of solution, J D the difference in velocity between water and salt, J S is flux of salt, P is pressure, π is osmotic pressure, C S is the average solute concentration, and L is phenomenological coefficients. The Onsager reciprocal relation states that L PD = L DP . This relation was found to be valid for a clay‐water‐salt system.