A Volatile Product from Radium

Abstract

IN the course of some recent experiments on the excited radio-activity from the radium emanation, some evidence has been obtained which points to the conclusion that the oemanation X of radium at one stage of the changes which it undergoes after being deposited on a solid body is slightly volatile even at ordinary temperatures. The effect which gives rise to this conclusion was first noticed in some observations on the rate of decay of the part of the excited activity deposited on a plate of copper immersed for a short time in dilute hydrochloric acid, in which the activity from a platinum wire exposed for a time to the radium emanation had been dissolved. When the copper plate with its active deposit had been placed inside a testing vessel and removed after a few minutes, it was noticed that a temporary activity, in some cases equal in amount to one or two percent, of the activity of the plate, was excited on the walls of the vessel. This activity increased to about three times Its original value in the course of thirty minutes after the removal of the active copper, and then decayed regularly to zero.