Cathode rays and physical chemistry
Perrin was born in Lille, trained at the École Normale Supérieure and earned his doctorate in 1897 for work on cathode rays and X-rays. He taught physical chemistry at the Sorbonne and became a professor in 1910. His early work included the negative charge of cathode rays and gas conductivity under X-rays.
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Brownian motion and sedimentation
Perrin measured the Brownian motion of suspended particles and their equilibrium distribution at different heights. His 1908 experiments supported Einstein’s account of molecular collisions and gave estimates of Avogadro’s number consistent with other methods. Molecular theory could thus be tested through measurable particle behaviour.
Books and scientific institutions
His 1913 book Les Atomes presented this research to a wider readership. Perrin also promoted research institutions including the organisation that became CNRS and founded the Palais de la Découverte. After the German invasion of France he moved to the United States and died in New York in 1942.