title: An Explanation of the Liesegang Phenomenon.
abstract: Periodic band precipitation in porous media is explained by means of the Hirsch effect (specific semipermeability of the precipitate occurring only as long as both the precipitate-forming ions are present). The possibility of getting Liesegang bands in immunological precipitates is underlined, and a suggestion is made how to avoid them.
authors.forename: C J
authors.initials: CJ
authors.lastname: VAN Oss
authors.forename: P
authors.initials: P
authors.lastname: Hirsch-Ayalon