Page:Popular Science Monthly Volume 76.djvu/282

278 escapes. High temperature or a powerful electrical field may produce the same effect.

If our atom belongs to the group of radioactive elements such as radium, thorium, etc., we shall see from time to time, if we watch attentively, a kind of explosion. Perhaps an electron will be hurled forth with enormous velocity, perhaps one of the sub-atoms, sometimes both. The positively charged sub-atom, after it has given up most of its energy by collisions, will attract to itself a pair of neutralizing electrons and settle down, a staid helium atom. The remainder of the original atom rearranges itself into a new condition of more or less stability, and we have a new atom. It is no longer an atom of radium, for instance, but an atom of something else; another element with an atomic mass some four units less, and differing from radium as gold does from mercury. Its spectrum will be different; its properties will be different. It may perhaps be a gaseous atom instead of an atom of a solid. And we shall see this process continuing at irregular intervals, the atom gradually becoming smaller until a state is reached which is so stable as to seem permanent.—And all these processes are taking place within the bounds of our diminutive tennis ball.

Here we have the transmutation of the elements of which the alchemists dreamed. It is true that these changes now seem to go on "like the stars without haste without rest" uncontrollable by human agencies, but one would be rash to predict the impossibility of such control.

I have pictured a radioactive atom. But need we make that limitation? The intervals at which these transformations occur vary greatly. Thus we are told that the average life of a radium atom is about 2,000 years, that of its first product but four days, and a similar product of another element, actinium, lasts but a few seconds. It is estimated that an atom of uranium or thorium lasts some thousand million years, but still eventually changes into another form. In our imaginary picture we need set no limits to our measurement of time. The 200,000,000 years that we are told the earth has endured may be but a mere incident in the life of an atom; and an element surpassing uranium as much as that does some of the more rapidly disintegrating substances would appear permanent by all known tests.

The atoms would thus appear to be crumbling, perishing—indeed their death-knell has already been sounded. I find it in a recent number of a scientific journal. I do not know the author, but the initials appended to it—W. R.—are those of the foremost chemist of England.

 Old Time is a'flying; the atoms are dying; Come, list to their parting oration: We'll soon disappear to a heavenly sphere On account of our disintegration.