Number 41 (Story #5), July 17, 1991 by Phillip F. Schewe and Ben Stein PRODUCING CRYSTALS IN HIGH GRAVITY reduces impurities in certain materials, contrary to scientists' original expectations. Using fast-spinning centrifuges which create artificial high-gravity fields, Soviet and French scientists have grown metal alloys with fewer imperfections (and with different microstructures) than those prepared under normal conditions. The pure materials, however, are only produced at certain "magical" values of the gravitational field strength. Scientists believe that high-gravity manufacturing processes may bring about purer semiconductors and alloys and may even rival low-gravity space labs as a means of growing purer crystals. (Science, 5 July.)