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Nonradioactive Materials: Hot-Atom Chemistry.—All the chemical procedures thus far discussed can be used also for nonradioactive materials. There are some techniques, however, which can be used only with radioactive substances. These result from recoil and electronic rearrangement effects, which accompany nuclear reactions and radioactive transformations. Otto Hahn (1879- ) and Lise Meitner (1878- ) in 1909 were the first to show the importance of radioactive recoil effects in chemistry.
The pure radioactive enzyme and the crude nonradioactive one were then separately subjected to centrifugation in a solution of cesium chloride, a simple, inorganic salt. Samples were withdrawn and tested for the presence of the enzyme amylase, either by measuring its radioactivity or by observing the action of the enzyme on a starch solution.
Scientists swarm around the plane—which will not exist until 38 years into the future—and find from manufacturers' nameplates on various parts—General Electric, Bendix, Westinghouse, Western Electric— that the strange craft is clearly an American product.
"But it's also very rapidly clear," Campbell goes on, "that it can't possibly exist. For one thing, it's radioactive all over to some degree—and one of the principal radioactives present is barium." But in the scientific world of 1930, barium is known positively to be nonradioactive. |
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