but which yet by electrical means can easily be detected, and their boiling-points and other properties investigated. Moreover the investigators of these strange substances are able to dissolve and precipitate, and perform ordinary chemical operations on, these utterly imponderable and hopelessly minute deposits of radio-active substances, because of the powerful means of detection which their ionizing power puts into our hands—even a few stray atoms being able by their ionizing power to discharge an electroscope appreciably.
13. Thus then it would appear that our theoretical conclusion concerning the inevitable radiation and loss of energy from electrically constituted atoms of matter, a loss which must involve them in necessary change and dissolution, meets with quite unexpectedly rapid confirmation; and it is for that reason that I feel willing to accept, tentatively and as a working hypothesis, this explanation of radio-activity. For how is radio-activity to be explained? It looks as if the massive and extremely complex atoms of a radio-active substance were liable to get into an unstable condition, probably reaching this condition whenever any part of it attempts, or is urged, to move with the velocity of light. I have shown elsewhere[1] that the mere fact of radiation will act as a resisting medium and increase the speed of the particles automatically, on the same principle that a comet would be accelerated if it met with resistance; since the inverse square law applies to electrical central forces. Electrical mass is not strictly constant: it is a function of speed, but in such a way that it is practically
- ↑ See Nature for June 11, 1903.
