ISEN-ASTC-L is a service of the Association of Science-Technology Centers Incorporated, a worldwide network of science museums and related institutions. ***************************************************************************** Take a look at Kinetic Carnival of Physics - Jearl Walker. In it he talks about Isotropic Fluids - the corn starch and water phenomena. Plus he seems to suggest that all mixtures of solids and fluids (including sand in air), quicksand, beach sand that is water saturated and even solid particles suspended in air exhibit these properties - but to a greater or lesser extent depending on the materials. My rather limited understanding is that essentially, when put under high shearing pressures the particles make contact with one another in a jumbled arrangement acting as a solid (essentially certain angles of the particle make contact with other particles while other spaces are left free (and water goes into those spaces)). However when left alone the water allows the particles to flow into more naturally occurring arrangements and the particles slip over one another with a layer of fluid between them - acting as a fluid. So when not under pressure the fluid aspect takes over the material and particles glide over one another in a more orderly fashion. By varying the degree of pressure you vary the solid/liquid characteristics exhibited. I have also been told that this is more complicated with corn starch because it has long chain molecules (like spaghetti) so exhibits the characteristics even "more so" do to its polymer style nature. Of course, I don't know if that's true or not (but it makes sense to me). William Katzman "The important thing is to never stop questioning." -A. Einstein Director of Exhibits "Are you sure about that Al?" -His wife. Catawba Science Center ph: (828) 322-8169 x307 fax:(828) 322-1585 [log in to unmask] *********************************************************************** More information about the Informal Science Education Network and the Association of Science-Technology Centers may be found at http://www.astc.org. To remove your e-mail address from the ISEN-ASTC-L list, send the message SIGNOFF ISEN-ASTC-L in the BODY of a message to [log in to unmask]