Again, again & again the telephone on Professor Harold Clayton Urey's littered desk rang one afternoon last week. "Thank you," said Dr. Urey to friends, students, colleagues. "Thank you....Thank you....Thank you." Someone brought into his office on Columbia University's campus a woodcock captured on a windowsill of the chemistry building. Dr. Urey suggested the bird be taken out of the city and freed in the woods. He was in a jovial mood. Word had just arrived from Stockholm that he had been awarded the 1934 Nobel Prize for Chemistry.

Dr. Urey, 41, is the third U. S. scientist to receive the world's richest prize (about $41,000) in Chemistry.* No award for Chemistry was made last year. The Physics prize will not be awarded this year.

Three short years ago the formula D20 would have been meaningless to chemists because there was no element corresponding to the symbol D. Now every chemist in the land knows that D2O means heavy water, that D is the symbol for the heavy isotope of hydrogen which Dr. Urey identified in the autumn of 1931 (TIME, Dec. 21, 1931) and subsequently named deuterium. Undoubtedly in considering last week's award the Swedish Academy took cognizance of the fact that no discovery in the physical sciences in recent years has stimulated more widespread research than D.

Dr. Urey's heavy hydrogen did not burst entirely unexpectedly upon the world, nor was its discovery in any way an accident. It was rather the result of ingenuity backed by sound logic. There were discrepancies in atomic weights. The oxygen atom should have weighed 16 times as much as the hydrogen atom, but it did not. Then it was found that oxygen had two isotopes* weighing 17 and 18 units respectively. Thus it began to seem more & more probable that hydrogen might also have one or more isotopes of its own. Birge of the University of California and Menzel of Harvard showed that the difference would be erased if one atom of hydrogen in every 4,500 had a nucleus twice the weight of the common nuclei. Allison of Alabama Polytechnic Institute found some curious magneto-optic effects in hydrogen which he chose to explain by the presence of a double-weight isotope.

Like the perturbations in planetary orbits that indicated the existence of a planet beyond Neptune, all this was evidence, not proof. Like the planet Pluto, heavy hydrogen had to be located. Dr. Urey knew that if its atoms had indeed a mass of two units, it would show spectrum lines of a predictable kind and position. The question was how to get the substance in sufficient concentration to show spectrum lines at all. It occurred to him that if liquid hydrogen were allowed to evaporate, the lighter atoms would pass off first, leaving the heavy ones in greater abundance. Hydrogen liquefies at --452DEG F. Dr. Urey had no apparatus for producing that sort of temperature. He asked his friend Ferdinand Brickwedde of the U. S. Bureau of Standards for help. Dr. Brickwedde obtained a gallon of liquid hydrogen, evaporated it to one cubic centimetre, bottled it, sent it to Dr. Urey at Columbia. Dr. Urey and George Murphy, his associate, put the precious drop in a vacuum tube, shot an electric current through it until it glowed brightly, split up the light with a diffraction grating. Three years ago this week, on Thanksgiving Day, they found the spectrum lines of heavy hydrogen exactly where they had predicted.

Since that winter improved methods of making heavy water have been devised at the Bureau of Standards, at University of California, by Dr. Urey himself. It is being made at Penn State, University of Michigan, University of Oregon, scores of other institutions in the U. S. and abroad. Dr. Urey's first cost of $150 per gram has dropped to $15 (about $75,000 per gallon). Princeton makes pure D20, estimates the cost at only $5 per gram. Ninety-five percent pure heavy water is available commercially at $20 per gram.

Heavy water is only 10% heavier than ordinary water, slightly more viscous, boils at 214 1/2DEG F. instead of 212DEG. Guppy fish, tadpoles and flatworms die in it, but mice fed with it seem to get tipsy. It has been found in slightly higher than normal concentration (one part in 4,500) in the Dead Sea, the Great Salt Lake, the sap and wood of willow trees, borax deposits. The hydrogen of honey, coal benzene and kerosene was found comparatively rich in D. But in the Sun's atmosphere only one atom of D in 100,000 of hydrogen appears to be present.

To chemists, according to Dr. Urey, the greatest importance of heavy hydrogen is that exchange reactions involving hydrogen can be traced, since the heavy and light atoms are as distinct as red and green. To physicists, the heavy nucleus, the deuton, has proved an invaluable atom-smashing projectile. To commercial chemists, interaction experiments between hydrogen and heavy hydrogen at low temperatures have offered hope that the cost of synthesizing alcohols and ammonia may be drastically reduced.

Born in Walkerton, Ind., Harold Clayton Urey was left fatherless when he was 6. His mother and later his stepfather helped him through University of Montana, from which he emerged a zoologist. The War shunted him into chemistry. Later he took his Ph. D. at University of California, studied in Copenhagen under Nobel Laureate Niels Bohr. He is married, has two daughters. He is a neat, square, plump-faced man who likes to extemporize on the piano, make charcoal sketches. Once he smoked two packages of cigarets per day. Now he chews gum instead.

* Others: Theodore William Richards (1914), Irving Langmuir (1932).

* Isotopes are varying forms of the same element, chemically alike but differing in density and atomic weight.

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