Abstract
THE velocity with which helium is cast out by radio-active bodies at the moment of change varies considerably from one element to another. Thus the radiant atoms of radium C possess a far higher velocity than those of uranium or ionium. This fact is apparent in the greater distance to which the “ rays of the former will penetrate in air or in any other substance. The distance traversed in air is known as the “range.” The following table shows the ranges of o rays from the various known radio-active elements. Thus we see that whereas the helium from radium C is projected nearly 7 centimetres, that from uranium only reaches 2-7 centimetres. In the thorium series, one of the elements, thorium C, attains a range of 8'6 centimetres. This is the longest known.
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From a lecture delivered before the Royal Dublin Society on February 3, by Prof. J. Joly, F.R.S.
This might, possibly, be realised by condensing water vapour upon the ions according to the method described by C. T. R. Wilson (Proc. R. S., June, 1911).
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Radiant Matter 1 . Nature 87, 98–100 (1911). https://doi.org/10.1038/087098a0
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DOI: https://doi.org/10.1038/087098a0