The Becquerel rays and the properties of radium / by R.J. Strutt.

  • Rayleigh, Robert John Strutt, Baron, 1875-1947.
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: The Becquerel rays and the properties of radium / by R.J. Strutt. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    again, and so on indefinitely. The time that the leaves take to diverge and collapse again once depends, of course, on how much radium is used. But with several milligrammes of a pure radium salt it is easy to make an apparatus which will go through its cycle in the course of a minute. This apparatus is probably the nearest ap- proach to perpetual motion that has ever been attain- ed. The divergence and collapse of the leaves is maintained without ceasing, and can only stop when the radium loses its activity. How long this may take, we do not very exactly know; but hundreds of years at least must elapse before the forces which cause the leaves to move have ceased to act. Enough electricity has been accumulated by the self- electrification of radium to even give an electric shock. It happened thus. Herr Horn had sealed up some radium salt hermeti- EarOo Fig. 16.—Ai-vangement for exhibiting the self-electrifioation of radium. A glass cylinder, a, is provided with a stopper, b. From this the tliin glass tube, d, containing radium, is hung by the glass rod, e, which serves as an insulating support, d is covered with a film of phosphoric acid, which makes it a conductoi'. At the other end is a brass cap,/', which carries the gold leaves, g. The whoJe is exhausted through h, which subsequently serves as a means of supporting it. d loses negative electricity, thus acquiring a positive charge, and tiie leaves, y, diverge. The divergence increases until the leaves touch the tinfoil strips, A h, which are connected to the earth through a wire, i-, sealed into the glass. This touching discharges the leaves, but they begin to diverge again immediately, if the radium preparation is active. This oscillation of the leaves goes oa indefinitely. cally in a tube of glass which possessed good insulating power; the negative charge was shot out in the form of yS-rays, while the positive charge remained in the tube, in which