CHAPTER XIII.
RADIO-ACTIVE PROCESSES.
254. Theories of radio-activity. In previous chapters, a
detailed account has been given of the nature and properties of
the radiations, and of the complex processes taking place in the
radio-active substances. The numerous products arising from the
radio-elements have been closely examined, and have been shown
to result from a transformation of the parent element through a
number of well-marked stages. In this chapter, the application of
the disintegration theory to the explanation of radio-active phenomena
will be considered still further, and the logical deductions
to be drawn from the theory will be discussed briefly.
A review will first be given of the working hypotheses which have served as a guide to the investigators in the field of radio-activity. These working theories have in many cases been modified or extended with the growth of experimental knowledge.
The early experiments of Mme Curie had indicated that radio-activity was an atomic and not a molecular phenomenon. This was still further substantiated by later work, and the detection and isolation of radium from pitchblende was a brilliant verification of the truth of this hypothesis.
The discovery that the β rays of the radio-elements were similar to the cathode rays produced in a vacuum tube was an important advance, and has formed the basis of several subsequent theories. J. Perrin[1], in 1901, following the views of J. J. Thomson and others, suggested that the atoms of bodies consisted of parts and might be likened to a miniature planetary system. In the
- ↑ Perrin, Revue Scientifique, April 13, 1901.
