DISCOVERY OF THORIUM

Press, Volume LXIII, Issue 12731, 18 February 1907, Page 7

DISCOVERY OF THORIUM

IMPORTANT FIND IN SOUTH AUSTRALIA. United Prcis Association—Br Electrio Telegraph—Copyright. ADELAIDE, February 16. What promises to bo a valuable discovery of monazite, containing thorium, has been mado at Kangaroo Island. Thorium is valued at £1700 per ton. The preciso percentage of thorium is at present not definitely known, but experts say it is high. Ono expert states that the crystals found are the largest in tho world. Tho interest of this discovery lies in tho fact that thorium ia used for tho manufacture of incandescent gas mantles, the increase in tho use of which has been a factor in sending up the price of thorium enormously of lato years. Thorium is also interesting because of its radio-activity. 'I his ia exceedingly small compared with that ot radium, but in somo respects it is eveu more interesting. If ammonia be added to a solution of thorium the thorium is precipitated in tho form of a solid. But tlie water retains the nctivitv of tho thorium, and the precipated thorium has lo«-,t it. On evaporating the water solution down to dryness and igniting it a small residue of intensely active matter remains which turns out, weight for weight, to be over a thousand times more active than tho thorium from which it was extracted. Professor Rutherford has called this active matter thorium N. On exnmining tbe thorium X and the precipitated thorium a month afterwnrds tbe investigator wiw astonished to find that, thorium X had completely lost its activity, while the thorium bad wholly regained it, and it was discovered thnt the rate of decay of the thorium X was exactly equal to the rate of recovery of the thorium. The only conceivable explanation of this fact (writes Professor Duncan in "The "New Knowledge) lies in the somewhat extraordinary proposition that the element thorium is constantly generating from itself another solid element, winch decays at the samo rnte at which it is generated.

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