The property of intrinsic luminosity is characteristic of radon in all states of aggregation and is one of the evidence of the changes in energy that accompany its decay. The intensity of phosphorescence is greatest in a solid – perhaps because of the smaller volume occupied – but both the gas and the liquid flow are strong. The color of light emitted by a solid varies from steel-blue at the melting point to orange-red at lower temperatures. Heat is also released during the disintegration of the emanation.
Continuous energy emission also manifests itself in the slow decomposition of carbon dioxide, carbon monoxide, ammonia, hydrochloric acid and water exposed to radon. It was also pointed out that when solutions of compounds of elements of the carbon group (silicon, titanium, zirconium, thorium, and lead) are exposed to the action of radon, carbon dioxide is always formed. This indicates the possibility that the molecules of these elements can degrade with the formation of carbon, the lowest member of the series. Radon induces the oxidation of wet mercury and turns the ordinary white violet glass.
At one time it was assumed that the replacement of copper by lithium and water with neon was observed, but the reliability of these observations is seriously questioned.
Within one or two days after its release, radon undergoes a slow compression to about half its original volume; later it slowly expands approximately 3 to 3.5 times compared to the original volume. This change corresponds to a change in the spectrum, and radon completely disappears in 3-4 days and gives way to helium.
The reason for the reduction is unclear, but it was observed in every sample that has been prepared so far, and possibly because of impurities. The slow expansion, which occurs later, can be satisfactorily explained on the assumption that the α particles emitted during the radioactive change of radon have such a high rate that they are forced into the walls of the vessel contained therein slowly. It was found that if the radon is enclosed in a glass tube whose walls have a thickness less than the range of its a-particles in the glass, the accumulation of helium can be observed in outer space. This confirms the previous explanation of the slow increase in volume and once again convincingly proves the identity of the helium atom with the α particle. The half-life of radon is 3.75 days.
Here it can be mentioned that the evolution of helium from radium was first proved by Ramsay and Soddy and confirmed by Himstedt and Mayer: the first assertion that radioactive elements are elements that undergo decomposition was first made by Jeffrey Martin. Assuming that the five alpha particles are displaced during the complete decay of one atom of radium, the volume of helium produced per day from 1 gram of radium should be 0.439 cubic meters. Mm. At N.T.P: the experimental determination of the sum were given by numbers that are in good agreement with this result. Since then, its production has been observed in many other radioactive changes.