COMMUXICATIONS TO THE EDITOR
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and Noyes3 have demonstrated a similar reaction. Extensions of these investigations are being continued. (3) G (1921)
11. Coleman and \V
A
Y o y c s , THIS J O U R N A L , 45, 2211
CHEMICAL RESEARCH DEPT. M. E. BROOK? B. RUDNER DAVISON CHEMICAL COMPANY 3, MARYLAND BALTIMORE RECEIVED APRIL 12, 1956
CRYSTAL STRUCTURE AND MAGNETIC SUSCEPTIBILITY OF AMERICIUM METAL'
Sir: We have obtained interpretable X-ray diffraction patterns of several small polycrystalline samples of americium metal of >99% purity, using Cu K a radiation and a 4.3-cm. radius camera. The metal was prepared on a micro scale by reduction of the trifluoride with barium vapor, in a tantalum crucible system and subsequently was annealed by slowly reducing the temperature from 800 to cn. 25" over a period of ten hours. The powder patterns have been indexed as doukle hexagonal close packed, a = 3.642 f 0.005 A., c = 11.76 f 0.01 A. The space group is D&,and the atomic positions are: two -4m in (0, 0, 0), (0, 0 , two -4m in (I/?, :/:
