RADIO-ACTIVITY
We saw at the very beginning of this little book that, from time immemorial, something corresponding to Atoms were regarded as the ultimate “building stones” of the universe—tiny particles, incapable of diversion, beyond which it was impossible to go. Beginning with Epicurus and Democritus, this idea took scientific form; it was held by many philosophers throughout the ages; it formed the basis of Dalton’s atomic theory, and was assumed by the Periodic Law. It was not until the last years of the preceding century that this idea was called into question. The discovery of radium, by the Curies, caused a sensation in the scientific world. How account for the phenomena observed? Radium seemed to give off energy continuously, without losing any; heat was constantly being radiated without lessening the original amount. Had the secret of perpetual motion been discovered? What was happening? The discovery of other radio-active elements only tended to increase the problem, instead of solving it. Here was some new property of matter, hitherto unsuspected, going on before the eyes of chemists, which they could not understand or explain.