As Professor Selig Hecht tells the story in his recent book, Explaining the Atom, “Urey interested F. G. Brickweddie at the Bureau of Standards, who proceeded to make a gallon of liquid hydrogen. Brickweddie then allowed the liquid to evaporate slowly until all but a gram (1/25 of an ounce) of liquid hydrogen was left, which he shipped to Urey”. With this specimen and the mass spectrometer, Urey and G. M. Murphy isolated the heavy isotope, and “for this exciting discovery,” says Hecht, ‘”Urey was awarded the Nobel prize in 1934″. (Nota de rodapé 14: Hecht, pp. 98-99.) (White 1949:213)
Now we have no desire to minimize the importance of this discovery as a scientific achievement. And we certainly do not wish to belittle Dr. Urea’s native and inborn abilities. But, we would like to ask. Was intelligence of a high order required for this discovery? What precisely did it involve? No new theory of atomic structure was advanced; on the contrary. Urey had the heritage of generations of workers at his disposal. Urey did not discover isotopes;  they had been found experimentally and explained theoretically by others. Isotopes of many elements had been isolated and identified before Urey. Techniques of isolation had been developed by Thomson, Aston, Bainbridge, and others. He did not invent the mass spectrometer; it is a descendant of the tube invented by Heinrich Geissler about 1862. He did not provide the liquid hydrogen or even manage its gradual evaporation. The idea that a light isotope would diffuse faster than a heavy one was not original; it had been tried out experimentally by Aston with positive results. What then did Urey contribute? (White 1949:213-4)
Again, let us repeat, we are not minimizing the inborn capacities of Dr. Urey. He may have a superlatively fine organization of nerves, glands, and sense organs. We have, however, implied that intelligence of a high order was not essential to the isolation of heavy hydrogen, and we now wish to make this implied conclusion explicit and unequivocal: it could have been achieved by a very ordinary intelligence. As a matter of fact, we believe that many a household problem—such as removing a stain from a dress or opening a recalcitrant jar of pickles—requires as much ingenuity, though perhaps not as much technical information—which is a matter of education, not native ability—as that required in the isolation of heavy hydrogen. Take a person of average intelligence, give him excellent technical training, put him in a well-equipped laboratory, and assuming some interest and enthusiasm on his part, how could he help but make some significant discovery? One cannot adventure very long with an electron microscope or a cyclotron without stumbling upon something new. And “stumbling upon” very aptly characterizes many significant advances in science. The reason that superlatively great advances in science are few is not because “genius” is rare but because great syntheses must be built upon, or grow out of, a multitude of minor ones. (White 1949:214)
WHITE, Leslie. 1949. The science of culture: a study of man and civilization. New York: Grove Press.