ABSTRACT
The rays are similar in all respects to the cathode rays produced in a vacuum-tube. The rays are probably like Rontgen rays, but of very great penetrating power. The rays are by far the most important. In addition to these rays two of the radio-elements give off radioactive emanations, which are in all respects like gases. The radiations from these emanations are not permanent, but fall off in a geometrical progression with the time. The radiation of the thorium emanation falls to half value in one minute, that from radium in four days. They have all the properties of gaseous matter in infinitesimal quantity. These results find their explanation if it is supposed that the particles projected form integral portions of the atom of the radioactive element. Prof. Everett found it difficult to believe that there was a sufficient store of energy in the atom to account for the effects observed.
