London: Constable & Co., 1916. First edition in English. Text illustrations and diagrams, index. Binding extremities rubbed, some discoloration to cloth near top corner of both covers. Rubberstamp mostly removed from front pastedown. A good, tight copy. Original brown cloth with spine stamped in gilt and front cover in blind. Octavo. xiv, , 211 pp. Item #14256
Jean Baptiste Perrin (1870-1942) was born in Lille, and studied at the École Normale Supérieure, where he began his study of cathode- and X-rays. He later taught at the University of Paris. “His earliest work was on the nature of cathode rays, and their nature was proved by him to be that of negatively charged particles. He also studied the effect of the action of X-rays on the conductivity of gases. In addition, he worked on fluorescence, the disintegration of radium, and the emission and transmission of sound. The work for which he is best known is the study of colloids and, in particular, the so-called Brownian movement. His results in this field were able to confirm Einstein's theoretical studies in which it was shown that colloidal particles should obey the gas laws, and hence to calculate Avogadro's number N, the number of molecules per grammolecule of a gas. The value thus calculated agreed excellently with other values obtained by entirely different methods in connection with other phenomena, such as that found by him as a result of his study of the sedimentation equilibrium in suspensions containing microscopic gamboge particles of uniform size. In this way the discontinuity of matter was proved by him beyond doubt: an achievement rewarded with the 1926 Nobel Prize” (Nobelprize.org biography).
"His most fundamental conclusion - that he had finally uncovered irrefutable proof for the real existence of atoms —contrary to the assertations and expectations of Ostwald, Mach, and others—was soon universally accepted and popularized in his book Les atomes' (1913), which went through many editions and translations” (D.S.B.).