Define a mixture with volume V containing a certain amount of clay (Vc) and sand (Vs), i.e. V = Vc + Vs. The intrinsic porosity of the clay is φc, defined as the ratio of pore volume in the clay V c p to the volume of clay, i.e. φc = V c p /Vc, and the intrinsic porosity of sand is φs = V s p /Vs. The surface areas of the pores in the clay and in the sand are noted S p and S s p respectively. S...