TRANSFORMATION OF ELEMENTS

Timaru Herald, Volume XIIC, Issue 13649, 17 July 1908, Page 3

TRANSFORMATION OF ELEMENTS

Mr A. T. Cameron gives an inierosfiug summary of recent rcuullb in laUmactivity in the April " ijcknce l'rogreoS." When an okctiic current is passed through a vacuum tube wu finu—(l) particles aii heavy hydrogen projected with enormous velocity in the direction opposite to the- current and .positively charged—tlio t>o-ealltd canal rays of Wein ; (2) u stream of ekctruiib, negatively charged—cathode ray:--; (5) second ary ether vibrations—the Konlgen rays. TJie various radiations from radio-active matter correspond to these effects, 'fne alpha rays correspond to l.he canal rays, and the gamma rays to the Kontgcn rays. Unfortunately they arc ail mixed up together very often; but they can be distinguished—(l) by tlioir power of jR-nelra-tion, and (2) by the clleot of a magnet upon (hem. The velocity of the particies shot off enabkseleetricty to pass through y. gas- (which it docs not ordinarily do), and ill lift gives a. means of measurinc; (he amount of them pm-enl. All forms of radio-active radiation, when I hey fail on any surface, liberate from it elect rom> I ravelling with comparatively low- velocity. \V>iy curious is- the effect, of radiation on precious stones and glass. Rubies become brown or pin!;, a yellow diamond becomes given, soda glass is coloured violet, poturdi-glass a iloep brown, and gold-glass ruby. U. is supposed thai these metallic irons are liberated in the glass and that, the colour is directly U> them. The radiation changes oxygen into ozone, and water into hydrogen p•roxide ; a.s it ehang'S yellow phosphoiin-. into the red variety—tlnte obviously all being cases in which ils energy helps lo build up higher molecular ";.«;;; regit tcs. Radium rays, like X-rays, produce painful burns. Most interest irig is the study of the life history of radio subsl;nur>-. ' ami on this iniirli iiejit, ha., burn thrown. The "half-hfo period'' ranges from a. kw seconds to millions of years in tin- e;isc of so fairly stable an clement »» uranium, which is nevertheli.TS the parent, or grandparent, of radium. No lewer than 2'l new elemeiil.s have been discovered by radioactive methods: and in l hi-.-c we must add uranium and thorium, known before their radio-activity was dtteeted. Of these 26 elements five are inactive; tl.ey represent " restiriji stages.'' Nin • or ten give alpha. p;n-ticl<.« alone, ami the I-, si. more or 1-us of the mixed red iation characteristic of radium. Only nine peisi.-i. for any appreciable liui". but I here is no reason why we should d'-iry liename of "element'' lo lie- remainder, though their iifo may be 100 rdioi I for "s to examine I hem by ordinary chcinic.-d means. They may be classilird into three large groups, ji.ccordiug as I hey are -.nee, ssive disintegration product.-! of uranium, thorium, or actinium. Their atomic weight cannot, of course, be directly calculated: but they are tentatively got at by the theory that each alpha particle is- the equivalent of an helium atom. Thus, every time an element is reduced by the less of one such particle we have to subtract four to get the new

atomic weight.. Thus, in the ease nf uranium there are inclusively twelve, ■stages. . Three are rayless and out; emits mi aljiha. particles. Making the theoretical subtractions in turn the final inactive product lias an atomic weight of 206.5, which agrees closely with that of the known element lead "(207). 'Hie half-life periods of the product* vary from three minutes to many years. The group then represents a definite ewe of " evolution of trie elements." .Similarly, thorium gives rise to eight products, the last of which when isolated should be inactive, and perhaps correspond to bismuth or 1o an unknown heavy element. One of ill* transformation isfag'is only lasts S3 seconds, so actinium given s<tcii products, one of which only lives about four seconds. Actinium is .-in element precipitated with On: cerium group. It its much more active tlian thorium.