Science: Thunder at Chalk River

When Swedish Scientist Berzelius in 1828 named his newly discovered element thorium—after Thor, god of thunder—the choice was perhaps more portentous than Berzelius guessed. Last week in Ottawa, Prime Minister William Lyon Mackenzie King told the House of Commons that Canada's huge atomic-energy project at Chalk River, Ont. is exploring the use of thorium as a source of atomic energy. This was the first public hint of large-scale atomic experiments with elements other than uranium.

A close relative of uranium, thorium is another radioactive, heavy element (atomic number 90, atomic weight 232.12) that disintegrates into lower-weight elements and eventually becomes lead. Of the three standard radioactive progressions — uranium-radium, actinium and thorium—those of uranium and thorium are the most alike. According to the Smyth report, thorium was considered as a basic source of atomic power, but uranium was chosen instead.

The earth's crust, scientists estimate, is composed of twelve parts per million of thorium and four parts per million of uranium. British India produced three-quarters of the prewar supply of thorium. Other deposits have been worked in Brazil, Australia, The Netherlands East Indies, and parts of the U.S.

Commercial uses are limited and prosaic—Welsbach gaslight mantles, carbon terminals for projectors, luminous watch dials. Since commercial production has never been reported in Canada, two possibilities are suggested: 1) the materials for Chalk River will be imported; or 2) under the wartime security blackout, a workable deposit of thorium has been discovered in Canada.