Radio-activity / by E. Rutherford.

  • Ernest Rutherford
Date:
1904
Catalogue details

Licence: Public Domain Mark

Credit: Radio-activity / by E. Rutherford. Source: Wellcome Collection.

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    to actinium, the two emanations should have identical rates of Baskerville1, working with thorium minerals, was able to obtain thorium less active to the photographic plate than ordinary thorium. He put forward the view that thorium was a mixture of two elements, one of which was active and the other inactive. These results were probably due to the separation of the active product Th. X from the thorium (see section 119). This process would temporarily greatly reduce the activity as tested by the photographic method. Until thorium is obtained permanently free from activity, the question whether the radio-activity is due to a small trace of very active matter, or to the thorium itself, must remain in doubt2 3. The fact that ordinary commercial thorium and the purest chemical preparation show equal activity supports the view that the effect is not due to a radio-active impurity, but to the element itself. If the activity of thorium is due to a small trace of active matter, this active substance is certainly not radium or actinium or any other known material. Hofmann and Zerban8 obtained a substance from pitchblende similar in radio-active properties to thorium. The activity of this product did not diminish much in four months’ interval. The substance was probably the same as Debierne’s actinium. They also examined the thorium minerals broggerite and clevite, but obtained only some active residues the activity of which decreased rapidly with the time. 23. Radio-active lead. Elster and Geitel4 found that lead sulphate obtained from pitchblende was very active. They con¬ sidered that the activity was due to admixture with radium, and by suitable treatment the lead sulphate was obtained in an inactive state. 1 Jour. Amer. Ghem. Soc. 23, p. 761, 1901. 2 In a recent paper (Ber. deutsch. chem, Ges. p. 3093, 1903) Hofmann and Zerban state that they have obtained a preparation of thorium from gadolinite which was almost inactive when tested by the electric method and conclude that pure thorium is not radio-active. 3 Ber. deutsch. chem. Ges. p. 531, 1902. 4 Wied. Annal. 69, p. 83, 1899.
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