‎PERRIN (Jean)‎
‎MOUVEMENT BROWNIEN et GRANDEURS MOLECULAIRES ---- EDITION ORIGINALE ---- TIRE-A-PART (OFF-PRINT) of Royal Institution of Great Britain weekly evening meeting, Friday, February 24, 1911 -- BEL EXEMPLAIRE‎

‎Londres, Clowers and son, 1911, un volume in 8 relié en cartonnage bradel (reliure postérieure), 19pp., 5 figures dont une planche hors texte‎

Reference : 8636

‎---- EDITION ORIGINALE et TIRE-A-PART (OFF-PRINT) de cette conférence faite en français par Jean PERRIN à la Royal institution of Great Britain le 24 Février 1911 ---- Perrin was awarded the Nobel Prize in physics, 1926 "for his work on discontinuity in the structure of matter, and in particular for his discovery of the equilibrium of sedimentation" --- "The work for which Perrin is best known is his investigation of Brownian motion, the erratic movements performed by microscopic particles in suspension in a fluid, now interpreted as being caused by the continous, irregular bombardment of the particles by the molecules of the surrounding medium. Perrin thought that collodially suspended particles undergoing Brownian motion would distribute themselves vertically in a definite way at equilibrium. By counting small particles of gum resin suspended in water, Perrin found that their number decreased exponentially with increasing height. He proved that this variation follows from kinetic theory and that from it he could calculate a value for Avogadro's number. Since the size of a water molecule appeared in the equation for the vertical distribution of the brownian motion particles, for the first time the sizes of atoms and molecules could be calculated from actual observations. As henri Poincaré wrote: "The brilliant determination of the number of atom (in a mole) made by Perrin has completed the triumph of atomism.... The atom of the chemists is now a reality.' " (Weber - Pioneers of Science. Nobel Prize Winners in Physics)**8636/M2‎