Abstract
SINCE very active preparations of radium have become available, a steady search has been going on in many quarters for agents which will respond to the radiations and convert them into visible light. The most powerful fluorescer towards the α radiations is Sidot's hexagonal blende, a crystallised form of zinc sulphide, which is especially suited for use with the emanation. The most powerful to the β radiation is willemite, a zinc silicate, which gives a magnificent green fluorescence, and is probably quite free from any phosphorescence after the action of the rays ceases. This if left in the radium emanation steadily increases in brightness as the excited activity, and with it the β radiation, is produced, and reaches its maximum some hours after the emanation has been introduced. The same is true of kunzite, a new variety of spodumene discovered by Dr. Kunz, and supplied by Messrs. Griffin and Sons, Ltd. The colour of the light might be variously described by different observers as salmon-pink, warm orange, or orange-yellow, according to individual opinion. Kunzite is a transparent gem-like crystal, and is one of the most beautiful examples of the fluorescent bodies at present available for demonstrating the luminous effects produced by the radium rays. It is, however, not very powerful compared with willemite or the platinocyanides. Being, like the diamond, transparent, it shines especially well when exposed in a tube to the action of the concentrated radium emanation, as the whole mass of the crystal contributes to the light effect. The growth of the luminosity after the emanation is introduced, owing to gradual production of the excited activity, is more marked than in the case of willemite, as kunzite hardly seems to respond at all to the α radiation. This experiment would be instructive as a lecture illustration to prove that the emanation only gives α rays, and that the β rays are produced only when time has been allowed for some of the emanation to change into the matter causing the excited activity.
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S., F. Fluorescent Bodies Excited by Radium . Nature 69, 523 (1904). https://doi.org/10.1038/069523a0
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DOI: https://doi.org/10.1038/069523a0