Letter | Published:

Isotopes of Uranium

Naturevolume 130pages475476 (1932) | Download Citation



WE have succeeded in finding evidence of several isotopes of uranium which emit alpha-rays. In the expectation that the proportion of actino-uranium would be larger the younger the mineral, uranium from Colorado carnotite was used, the age of which has been variously estimated at from 170,000 to 7,000,000 years. The half-periods estimated by Wilkins1 and by Rutherford2 for actino-uranium, from quite different methods of reasoning, were 2.5 and 4.2 × 108 years respectively. The corresponding alpha-ray range would be about 3.2 cm.

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  1. 1

    NATURE, 117, 719; 1926.

  2. 2

    NATURE, 128, 313; 1929.

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  1. University of Rochester, Rochester, N.Y.

    • T. R. WILKINS
    •  & W. M. RAYTON


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