Villard, Paul

Figure 1.1-11 Paul Villard (1860-1934) [97] (photo used with permission from the Acaddmie des Sciences).

Early research on hydrothermal reactions was also carried out by Charles Friedel, an instructor at the Ecole Normale Supdrieure [108], the same institution where Paul Villard received his education. Over many years Charles, and later his son Georges Friedel, published a series of papers on the reaction of minerals in H2O at temperatures and presumably also pressures far above critical, starting with the preparation of quartz in 1879 [109,110]. Charles Friedel is more famous for his discovery of the Friedel-Crafts alkylation of aromatics. The works of de LaTour, Daubr6e and the Friedels together ensured that the first experimental reactions of and in SCFs were those of H2O, as reviewed in great detail by Morey [111]. 

E. Picard, La Vie et L OEuvre de Paul Villard et de Georges Gouy, Academic des Sciences, Gauthier-Villars, Paris, 1937. 

In 1899, Ernest Rutherford began to investigate the nature of the rays emitted from uranium. He found two particles, which he called alpha and beta particles. Soon he realized that uranium, while emitting these particles, was changing into another element. By 1912, over 30 radioactive isotopes were known, and many more are known today. The gamma ray, a third type of emission from radioactive materials similar to an X-ray, was discovered by Paul Villard (1860-1934) in 1900. Rutherford s description of the nuclear atom led scientists to attribute the phenomenon of radioactivity to reactions taking place in the nuclei of atoms. 

Ernest Rutherford (1871-1937) identified two types of radiation from radioactive materials, alpha (a) and beta (j8). Alpha particles carry two fundamental units of positive charge and have essentially the same mass as helium atoms. In fact, alpha particles are identical to He ions. Beta particles are negatively charged particles produced by changes occurring within the nuclei of radioactive atoms and have the same properties as electrons. A third form of radiation, which is not affected by electric or magnetic fields, was discovered in 1900 by Paul Villard. This radiation, called gamma rays (y). 

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