File:Radiography, x-ray therapeutics and radium therapy (1915) (14757397412).jpg

Identifier: radiographyxrayt00knoxuoft (find matches)
Title: Radiography, x-ray therapeutics and radium therapy
Year: 1915 (1910s)
Authors: Knox, Robert, 1868-1928
Subjects: Radiography Radiotherapy X-rays
Publisher: London : A. & C. Black
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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ath, obtained by the application ofheat, the original grouping is regained and the colour disappears. Althoughthis refers chiefly to alterations in the physical nature of a substance,many chemical changes are also produced, presumably by upsetting thearrangements of the bonds which unite atoms into definite molecular groups.It should now be clear from the nature of ionisation that an electrifiedwire brought into a mass of ionised gas ^\^ll be diselectrified by attracting _ to it ions of the opposite charge,and A\ill repel theothers. Thus,negatively chargedinitially the wirewill attract posi-tive ions, andgradually becomeneutral. A stripof gold or alu-minium leaf at-tached by one endto such a wire willstand out from itwhen the wire iselectrified, andtherefore a verysimple method ofdetecting the pres-ence of ions in agas consists in ob-serving the movement of the free end of the gold leaf when a radioactive bodyapproaches the wire. It is, in fact, the basis of all measurements of radio-
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FlG. 220.—Special form of gold leaf electroscope.(For description see p. 341.) KADIUM EMANATION 333 activity, and the electroscope sho^^^l iii Fig. 220 is an instrument embodpngthis principle. Its detailed description must, however, be deferred till later. Radium Emanation The residue that remains when a radium atom has expelled an Alphaparticle is no longer radium. It is an atom of a new substance. The pro-perty whereby it clmig originally to adjacent atoms and in the aggregate

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