A history of chemistry from the earliest times till the present day / by the late James Campbell Brown; with a portrait and one hundred and six illustrations.
- James Campbell Brown
- Date:
- 1913
Licence: In copyright
Credit: A history of chemistry from the earliest times till the present day / by the late James Campbell Brown; with a portrait and one hundred and six illustrations. Source: Wellcome Collection.
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![sparked electrically for the purpose of observing its spectrum. After some days, on observing it again, he saw faintly the spectrum line of helium. The helium line became more marked later, and then disappeared. Subsequent experiments proved that the emanation is not capable of a lasting existence and if kept in a sealed tube for a month becomes almost entirely disintegrated, and the tube then contains helium. The fact is curious, and we shall refer to it later. Radium, according to Rutherford, passes through a series of rapid changes by splitting of particles, and then finally gives rise to two slow-transformation products. The changes are shown by Rutherford diagrammatically, thus : RADIUM, giving off emanation and alpha rays. . 1. Radium einanation, giving off alpha rays. 2. Radium A, giving off a]j:>ha rays. 3. Radium B, giving off no rays. 4. Radium C, giving off alpha, beta and gamma rays. 5. Radium I), giving off no rays. 6. Radium E, giving off beta rays. 7. Radium F, giving off alpha rays, and probably identical with 'polonium. 8. Radium G, giving off no rays, and probably some well- known element, most probably lead. Radio-activity, although most strongly manifested in the group of elements we are now considering, is not confined to these, but as we already mentioned is slightly exhibited by many bodies. J. J. Thomson {Proc. Cambr. Phil. Socy., Vol. 12, p. 391), states that eighteen samples of water of different origin showed the presence in small quantities of a radio- active gas, which behaved like the emanation from radium. Sand, glass and other substances were shaken with inactive water, and the emanation removed by boiling, and tested in the usual manner. The emanation, as in the case of radium, falls in four days to half its value ; the induced radio-activity, in forty minutes. From this it follows that traces of radium are widely distributed in the earth’s crust. Salts and metals were also examined, but with negative results. Although the](https://iiif.wellcomecollection.org/image/b24870614_0577.jp2/full/800%2C/0/default.jpg)
