A Review of:“Crystals in Gels and Liesegang Rings:” H.K. Henlsch,Cambridge University Press,Cambridge, New York, 1988, 197 pages, $54.50.

A physical model for solute dispersion and nonlinear adsorption in media with random variable porosity is considered in the present study. A spectrum of longitudinal random porosities is generated by the random number generator to illustrate the applications and to assess its effect on the characteristics of solute dispersion and nonlinear adsorption. The complex dispersion/adsorption model can be effectively tackled with accuracy by an implicit finite difference method. It is shown that if the random porosity fluctuations do not deviate more than 92, 60 and 30% from its average, a simple dispersion/adsorption model with constant average porosity can predict, respectively, an average solute concentration within IS, 10 and 5% of those predicted by a more complex model with random variable porosity.