Paul Ulrich Villard

Paul Ulrich Villard ( born September 28, 1860 in Lyon, † January 13, 1934 in Bayonne ) was a French physicist and chemist. He discovered in 1900 while working on the radium γ - radiation as a third component of radiation.

  • 4.1 Literature
  • 4.2 Notes and references

Life

Paul Villard in 1881 began training at the École Normale Supérieure in Paris, where he graduated in 1884 with the Agrégation. As a teacher, he taught in the following years various government Lycéen in Paris, Orléans, Bordeaux, Coutances, Rouen and Montpellier. With the support of Marcelin Berthelot Villard was " Chargé de conférence " at the Science Faculty of the University of Montpellier and was able to do some experimental research there. However, he returned to Paris, so he asked to be relieved of his teaching duties. In Paris Villard turned to the director of the chemistry laboratories of the École normale supérieure Henri Debray (1827-1888) and asked for permission to work in his lab, which was granted. In the chemical sector in the Rue d' Ulm, he spent the rest of his scientific career. 1904 granted him Lespieau Robert ( 1864-1947 ) a small private laboratory.

1904 Villard was awarded the Prix Wild and 1907, the Prix La Caze. On December 28, 1908 he was elected to the Académie des sciences in place of Eleuthère Mascart a member of their section Physique Générale. He held up well ahead of Édouard Branly and other competitors. When performed on November 23, 1908 vote Villard was still inferior Edmond Bouty. Villard was also a member of the Société française de physique, the Société française des électriciens and the Société des amis des sciences, honorary member of the Société de radiology médicale de Paris and corresponding member of the Société industrielle de l' Est.

Towards the end of his life Villard accepted a " Pension d' honneur " of the Caisse nationale des Sciences. Due to his deteriorating health, he was forced to spend much time outside of Paris and died in early 1934 in Bayonne. Villard was an officer of the Légion d' Honneur.

Work

Villard's first research focus was the study of gas hydrates. Together with Robert Hippolyte de Forcrand (1856-1933) he established in 1888 the temperature dependence of hydrogen sulphide and chlorine methane hydrates. In the same year he succeeded hydrates of methane, ethane, ethene, ethyne and nitrous oxide produce, their physicochemical properties, he examined in the following years. 1890 Villard examined the hydrates of propane and 1896 those of argon. Between 1888 and 1896 he published nine articles on the physicochemical properties of these hydrates in the Comptes Rendus de l' Académie des sciences. This work was also the basis of his dissertation.

1897 Villard began using a Crookes tube to examine the X-rays recently discovered. In a first note, he reported on their effects on photographic plates. Villard wanted to find out where the material originates from the cathode rays are formed. He noticed the reducing action of the cathode rays when they met coated with lead sulfate or copper plates. This Villard drew the (wrong) conclusion that the cathode rays stocks of hydrogen, which was adopted at the tube surface. Hydrogen particles bombarding the cathode would, there is negatively charged and subsequently repelled by the cathode, to form the cathode ray tube. Villard revised his view in the second edition of his book Les Rayons cathodiques of 1908 and was followed by Joseph John Thomson representation that the cathode rays consist of electron.

Villard examined in further chemical effects of the X-rays, in particular caused by them glass coloration. When Pierre and Marie Curie reported similar effects of radium rays Villard was awakened interest in radioactivity. He would receive some Millgramm a low-level radioactive salt and began to investigate the reflection and refraction properties of cathode rays and beta rays. Villard directed to the radiation emitted by the radioactive source beta rays with a magnetic field and recorded on them in two successively arranged, by an aluminum foil separated photographic plates. He discovered a new type of radiation penetrating. His results were announced on April 9, 1900 during the meeting of the Académie des sciences. Henri Becquerel, who faced the observations Villard skeptical at first, but this confirmed soon. Villard gave the new radiation no name. The term γ - radiation goes back to Ernest Rutherford, who chose it as a continuation of the 1899 notation introduced α - and β - radiation 1903.

1904 Villard had almost the whole year-long dispute with Henri Pellat ( 1850-1909 ), who believed he had discovered that cathode rays were subjected to a magnetic field by an anisotropic friction during the passage. However, Villard could convincingly argue that a " Magnetofriction " does not exist.

Between 1906 and 1908 Villard developed a theory of the auroral phenomena. He calculated the paths to cover the cathode rays (electrons) under the influence of the geomagnetic field. He tried the look to explain the geographical distribution and the movements of the aurorae on this basis.

1908 Villard presented his " Radiosklerometer " ( radiation hardness meter ) in front of a measuring instrument for determining the penetration capability ( "hardness" ) of X-rays by the electrometer principle. As a new unit he suggested the amount of X-ray radiation ( esu, charge unit in the cgs system 1) is released by ionization in a volume of one cubic centimeter ( 1 cc) of air at standard conditions for temperature and pressure one electrostatic unit before. On a similar definition based the subsequent X-ray unit.

Invented by him Villard circuit, a one-way converter circuit with voltage doubling, which is mainly used to power X-ray tubes, is named after him.

Writings (selection )

  • Les Rayons cathodiques. Scientia, 1st Edition, Gauthier - Villar, Paris 1900 ( gallica, archive.org ).
  • Les Rayons cathodiques. 2nd edition, Gauthier -Villars, Paris, 1908.

Journal articles

Villard wrote, among other things, contributions to Comptes Rendus de l' Académie des sciences, Journal of Physics, Journal le Radium, Annales de chimie et de physique, Bulletin de la Société française des électriciens, Bulletin de la Société d' Encouragement, Revue générale des sciences, Revue scientifique and Bulletin de la Société française de photographie.

  • Sur l' hydrate d' hydrogène sulfurs. In: Comptes Rendus de l' Académie des sciences. Volume 106, 1888, pp. 849-851 ( with Robert Hippolyte de Forcrand; online)
  • Sur la formation of hydrates de gaz. In: Comptes Rendus de l' Académie des sciences. Volume 106, 1888, pp. 939-941 ( with Robert Hippolyte de Forcrand; online)
  • Sur l' hydrate de chlorure de methyls. In: Comptes Rendus de l' Académie des sciences. Volume 106, 1888, pp. 1357-1359 ( with Robert Hippolyte de Forcrand; online)
  • Sur la composition of the hydrates d' hydrogène Sulfure et de chlorure de methyls. In: Comptes Rendus de l' Académie des sciences. Volume 106, 1888, pp. 1402-1405 ( with Robert Hippolyte de Forcrand; online)
  • Sur quelques nouveaux hydrates de gaz. In: Comptes Rendus de l' Académie des sciences. Volume 106, 1888, pp. 1602-1603 (online).
  • Sur quelques nouveaux hydrates de gaz [ Note]. In: Comptes Rendus de l' Académie des sciences. Volume 111, 1890, pp. 302-305 (online).
  • Sur la composition et la chaleur de formation de l' hydrate de protoxides d' azote. In: Comptes Rendus de l' Académie des sciences. Volume 118, 1894, pp. 646-649 (online).
  • Sur les propriétés physiques you protoxides d' pure azote. In: Comptes Rendus de l' Académie des sciences. Volume 118, 1894, pp. 1096-1099 (online).
  • Sur l' hydrate carbonique et la composition of the hydrates de gaz. In: Comptes Rendus de l' Académie des sciences. Volume 119, 1894, pp. 368-371 (online).
  • Sur les propriétés of gaz très purs voisinage au point du critique. In: Journal de Physique théorique et Appliquée. Episode 3, Volume 3, 1894, pp. 441-451 ( doi: 10.1051/jphystap: 018940030044100, PDF).
  • Sur la dissolution of the solid dans les vapeurs. In: Comptes Rendus de l' Académie des sciences. Volume 120, 1895, pp. 182-184 (online).
  • Propertys physiques de l' acetylenes; hydrate d' acetylenes. In: Comptes Rendus de l' Académie des sciences. Volume 120, 1895, pp. 1262-1265 (online).
  • Propertys de l' acide carbonique solid. In: Comptes Rendus de l' Académie des sciences. Volume 120, 1895, pp. 1413-1416 ( with R. Jarry; online).
  • Combinaison de l' argon avec l'eau. In: Comptes Rendus de l' Académie des sciences. Volume 123, 1896, pp. 377-379 (online).
  • Sur les effets de mirage et les différences de Densités qu'on observe dans les tubes de Natterer. In: Journal de Physique théorique et Appliquée. Episode 3, Volume 5, 1896, pp. 257-266 ( doi: 10.1051/jphystap: 018960050025700, PDF).
  • Dissolution of the solid liquides et dans les gaz. In: Journal de Physique théorique et Appliquée. Episode 3, Volume 5, 1896, pp. 453-461 ( doi: 10.1051/jphystap: 018960050045301, PDF).
  • Étude of gaz liquéfiés. In: Annales de chimie et de physique. 7th episode, Volume 10, pp. 387-432 (online). - Part of the dissertation
  • Éttude expérimentale of hydrates de gaz. In: Annales de chimie et de physique. 7th episode, Volume 11, 1897, pp. 289-394 (online). - Part of the dissertation
  • Sur le voile photographique en radiography. In: Comptes Rendus de l' Académie des sciences. Volume 125, 1897, pp. 232-234 (online).
  • Sur la diffusion of rayons cathodiques. In: Comptes Rendus de l' Académie des sciences. Volume 127, 1898, pp. 223-224 (online).
  • Sur les rayons cathodiques. In: Comptes Rendus de l' Académie des sciences. 1898-1900: [ Part 1 ]: Volume 126, 1898, pp. 1339-1341 (online).
  • [ Part 2 ]: Volume 126, 1898, pp. 1564-1566 (online).
  • [ Part 3 ]: Volume 127, 1898, pp. 173-175 (online).
  • [Part 4 ]: Volume 130, 1900, pp. 1614-1616 (online).
  • On the chemical action of the X -rays. In: Philosophical Magazine. Episode 5, Volume 49, Number 297, 1900, p 244 ( doi: 10.1080/14786440009463840 ).
  • [ Part 1 ]: Volume 142, 1906, pp. 1330-1333 (online).
  • [ Part 2 ]: Volume 143, 1906, pp. 143-145 (online).

Evidence

Arrondissement of Lyon France Marcellin Berthelot Pierre Curie Electroscope Henri Abraham Integrated Authority File
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