The radium content of all the working standards at the Bureau are determined by comparison with this. This radium standard is preserved at the National Bureau of Standards at Washington, D.C., and is the primary radium standard of the United States. of radium chloride, equivalent to 15.40 mg. It is designated by the Committee as 'Secondary Radium Standard No. 6,' and is certified to have contained in the autumn of 1913, 20.28 mg. In December, 1913, the United States received its standard. These secondary standards are compared directly both with the International Standard in Paris and with the Vienna Standard. "The International Committee on Radium Standards also arranged for the preparation of standards for those governments that required them. The job of preparing multiple standards for distribution fell to a chemist, Otto Hönigschmid in Vienna, who was expert in gravimetric measurements and a leading authority on measurements of atomic weights. The preparation of a radium standard was assigned to Marie Curie, and in 1911 she prepared 21.99 milligrams of pure radium chloride in a sealed glass tube. The second order of business for the committee was to agree on an international standard that could be used to intercompare radium preparations from the principal laboratories in North America, UK, France, Germany and Austria. Her definition was "la quantité d'émanation en équilibre avec un gramme de radium." That is, that quantity of 222Rn (3.8 day half life) in equilibrium with one gram of its parent 226Ra. (A working amount of radium at the time was of the order of a few milligrams of the element.) Marie Curie felt that it was inappropriate to use the name Curie for an infinitesimal amount of material, so she insisted that a Curie correspond to a larger amount. It was quickly agreed that the unit for radioactivity would be the Curie in memory of Pierre Curie, but there was considerable discussion over the amount of activity that would correspond to 1 Curie. The first order of business of this committee was to agree to the quantity and unit for radioactivity. Marie Curie, who would soon receive a second Nobel prize, this time for chemistry, had strong ideas about the directions to take towards international standards. Eve, a colleague of Rutherford's from McGill Hans Geitel, a German physicist from Wolfenbüttel Otto Hahn, a German chemist who had spent 1905 - 1906 with Rutherford in Montreal Stefan Meyer, an Austrian physicist who was head of the Institute for Radium Research in Vienna Egon von Schweindler, a German physicist and Frederick Soddy, another collaborator of Rutherford's from McGill. Other members of the committee were Bertram Boltwood, a radiochemist from Yale University and close colleague of Rutherford André Debierne, a colleague of Marie Curie's Arthur S. Rutherford had recently moved from McGill University in Montreal to the University of Manchester in the United Kingdom. The two most influential members of this committee were the Nobel prize winners Marie Curie and Ernest Rutherford. The International Radium Standards Committee met in Brussels in September 1910 in connection with the International Congress on Radiology and Electricity.
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