Page:Modern Views on Matter.djvu/16

 8 an inch in diameter, the diameter of an atom of matter on the same scale is a mile and a half. Or if an atom of matter is represented by the size of this theatre, an electron is represented on the same scale by a printer's full stop. It is well to bear this extreme smallness in mind in what follows.

An atom is not a large thing, but if it is composed of electrons, the spaces between them are enormous compared with their size as great relatively as are the spaces between the planets in the solar system.

4. My next thesis is that these electrons or minute charged corpuscles can exist separately, for they can be detached from their atoms of matter at an electrode, not only in electrolytic liquids but also in gases, and when thus released from their thousandfold more massive atom, they fly away from the negative electrode with prodigious speed, because they are acted on by the same electrical propelling force as before, but now have hardly anything to move.

These isolated flying particles travel a long distance in rarefied gas, and are known as cathode rays. They were studied by Varley, Hittorf, Crookes, Lenard, and others, both inside and outside vacuum-tubes, and they are now known to be flung off spontaneously from many substances. When stopped suddenly by a massive obstacle, they give rise to the X-radiation discovered by Röntgen. At first these cathode rays were thought to be atoms of matter, though their extraordinary penetrating power rendered such a hypothesis difficult of belief, and caused Crookes to speak of them as matter in a fourth state. They are, however, certainly energetic