We
have here to do with a secondary reaction correlative to the
production of the emanation, after which radium undergoes the
transformations which will be studied later on.
The method of analysis founded by M. and Madame Curie has enabled
other bodies presenting sensible radioactivity to be discovered. The
alkaline metals appear to possess this property in a slight degree.
Recently fallen snow and mineral waters manifest marked action. The
phenomenon may often be due, however, to a radioactivity induced by
radiations already existing in the atmosphere. But this radioactivity
hardly attains the ten-thousandth part of that presented by uranium,
or the ten-millionth of that appertaining to radium.
Two other bodies, polonium and actinium, the one characterised by the
special nature of the radiations it emits and the other by a
particular spectrum, seem likewise to exist in pitchblende. These
chemical properties have not yet been perfectly defined; thus M.
Debierne, who discovered actinium, has been able to note the active
property which seems to belong to it, sometimes in lanthanum,
sometimes in neodynium.
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