Radium: its physics & therapeutics. / by Dawson Turner.

  • Turner, Dawson, 1857-1928.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Radium: its physics & therapeutics. / by Dawson Turner. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    it with a uranium salt, and placed it outside in the sunlight; he found that the plate was affected just as though it had been exposed to the X rays, for one of the extraordinary properties of the X rays is their power of penetrating opaque bodies and of affecting photographic plates. He thus discovered that uranium when exposed to sunlight gave off a radiation akin to the X radiation. But he went farther, for one day it happened to be raining, and he placed his photographic plate with the uranium upon it inside a cupboard ; on developing this plate he found it as much affected or fogged as the others which had been in the suuHght. He was not slow to see the importance of this, and he repeated the experiment, taking care that the uranium was kept in the dark all the time. The result was the same: the plate was as much affected in the dark as in the light, and neither phosphorescence nor sunhght had anything to do with it. He thus arrived at the epoch-making discovery of radio-activity. The pro- perty is an inherent one of the element uranium; it is found in all its compounds, and the radio-activity of such a compound is proportional to the amount of uranium which it contains. Thus it is an atomic property, and no chemical or ph3^sical processes to which the uranium has been subjected have so far been able in the smallest degree to affect its radio- activity. It remains the same at the heat of the electric furnace and at the cold of Hquid air. Other substances were soon tested for the same propen^ , Shcmidt found that thorium and its compounds, and