Word: protoactinium
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...pinpoint the Pleistocene. Developed at the University of Miami by Dr. John Rosholt of the U.S. Geological Survey and Italian-born Dr. Cesare Emiliani, it depends on the fact that a tiny amount of uranium is dissolved in all sea water. When it slowly decays radioactively, it yields protoactinium 231 and thorium 230, both of which attach themselves to sediment particles and sink slowly to the bottom. There they in turn decay, but protoactinium 231 decays faster than thorium 230. The age of sediment on the ocean floor can therefore be determined by measuring the relative abundance...
Slick-haired young Dr. Aristid von Grosse, research chemist of Chicago's Universal Oil Products Co., created a stir at a chemistry convention summer before last by exhibiting a speck, weighing one-tenth of a gram, of pure protoactinium which he had isolated. It was the first of the 92 elements to be isolated in the U. S. and this crumb constituted the world supply. Last week Dr. von Grosse created another stir by revealing that the world supply of protoactinium had unfortunately disappeared...
Heavier than any other element except uranium, protoactinium is radioactive. It is 25% rarer than radium in pitchblende. One ton of that mother ore was reduced to extract a half gram of protoactinium oxide. In a phosgene chlorinating bath this was transposed to a chloride. Using the method evolved by General Electric's famed Irving Langmuir. Dr. von Grosse spread the chloride on a tungsten filament in a vacuum, heated the filament, boiled off the chlorine, obtained his bit of pure protoactinium...
Last month Dr. von Grosse asked to have the world supply of protoactinium back for a while so that he could make more photographs. He took it into a darkroom illuminated only by the red glow of a photographic lantern, arranged his microscope and camera. In shaping the tungsten thread to which the protoactinium clung, he was a little too rough. The delicate element crumbled to invisible dust...
Dismayed but not losing his presence of mind. Dr. von Grosse laboriously located the crumbs by microscopic search, popped them into a tube of hydrofluoric acid where they disappeared beyond even microscopic view. From the acid. Dr. von Grosse said last week, he hopes eventually to extract the protoactinium in a single lump which may once more be seen under a magnifying glass...
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