Porosity and Water Content of Soil
 

Porosity - volume of voids divided by total volume

n = V_v/V

where V_v = volume of void space

V = volume of sample

e = V_v/V_s

where V_s = volume of solids

Note:

V = V_v + V_s

where W_w = mass of water in soil

W_s = mass of solid particles

where V_w = volume of water

R_s = V_w/V_v

Particle Density - weight of solids divided by volume of soilds
 

Capillary Forces

Attraction (surface tension) between liquid and solid causes fluid to be pulled upward against gravity. How high the fluid rises depends on pore throat radius