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The Structure of Monodisperse Foam

The foams that we encounter from morning (while shaving or drinking cappucino) to evening (while dishwashing or drinking beer) are random packings of polydipserse gas bubbles in liquid. Bubbles of EQUAL volume are readily produced in the laboratory, so how do these arrange when packed together in a monodisperse foam? Experiments show that both ordered crystalline foam or Bernal random close sphere packings are possible, depending on experimental details (e.g. bubble size, size of container, structure of walls). I will present recent X-ray tomography data for foams and also report on the successful realisation of the so-called Weaire-Phelan structure in liquid foam. Suggested in Dublin in 1994 as the ideal foam structure, it was only produced experimentally in 2011, again in Dublin.