Number 156 (Story #1), December 17, 1993 by Phillip F. Schewe and Ben Stein SUPERCONDUCTIVITY AT 250 K (-10 F) has been reported by a group of scientists at the Ecole Superieure de Physique et de Chemie in Paris. Michel Lagues and his colleagues synthesized a BiSrCaCuO compound with a unit cell comprising eight adjacent CuO planes. This development seems to bear out the general idea that high temperature superconductivity happens mostly in copper-oxygen planes and that the more such contiguous planes the better. The French researchers used beam epitaxy to lay down the atomic layers one by one, a cumbersome process that would be difficult to implement on an industrial scale. Reports of superconductivity in complex materials at these temperatures have been made before, only to be withdrawn, so some scientists such as Venky Venkatesan (301-405-7320) of the University of Maryland are skeptical. However, in contrast to these earlier materials, Lagues' sample remained superconducting for weeks. (Science, 17 Dec.)