Liquid money or hard cash? Drowning into granular material
  In British English, the term "hard cash" refers to the form of payment using coins or bill, rather than cheques or credit or money transfer. In American English, it is often prefixed by the adjective "cold". On the contrary, in Italian the equivalent expression "denaro liquido" can be literary translated as "liquid money". In French the expression is equivalent with the additional factor, with respect to the rest of this discussion, that money becomes "argent". We have therefore two very different points of view: Is money hard and cold, or rather liquid and "jingling" ("moneta sonante")? As usual, we shall investigate this topic starting from some comics about the duck family. 
Franco Bagnoli
physics.pop-ph