Physics of Finely Divided Matter: Proceedings of the Winter School, Les Houches, France, March 25 April 5, 1985 : Springer : 9783642933035 : 3642933033 : 23 Aug 2014 : The Second Winter School on the "~hysics of Finely Divided Matter" was held at the Centre de Physique des Houches from 25 March to 5 April 1985. This meeting brought together experts from the areas of gels and porous media. People with different backgrounds - chemists, physicists - from university as well as industrial labora­ tories, had the opportunity to compare their most recent experimental and theoreti­ cal results. Although the experimental situations and techniques may seem at first sight unrelated, the theoretical interpretations are very similar and may be divided roughly into two categories: percolation and aggregation. These are present for the description of the synthesis of some gels as well as for a description of the struc­ ture of packings. They are also a precious help for understanding flows in porous