Various properties of BeH/sub 2/ are predicted, based on the properties of neighboring hydrides. Included are predictions of the stability of the Be-H bond, the stability of an ionic lattice for BeH/sub 2/, polymeric structure, and density.

Neutron detector traverses of the untamped Oy (Godiva) and the Tu- or Ni-tamped Oy (Topsy) metal critical assemblies have been obtained by counting the following types of radiation : 1) y-activity of U 235 and U238 fission products; 2) fission fragments of Np 237 in a spiral chamber; 3) and Beta -activity of Au and S. At a few positions within the assemblies, and for the U235 fission spectrum, cross section ratios of a number of pairs of fissionable isotopes were determined by means of a comparison fission chamber. At the center of Godiva, af(25)\af(28) = 6.2, and this ratio for the Topsy Oy-Tu assembly ranges from 6.8 at the center to 76 at a radius of 8-1/4”. Results of radiochemical analyses for fission and other reaction products, by Group J-11, are listed in an appendix.

The vapor pressure of nickel carbonyl was determined with material obtained by laboratory preparation with CO and Ni powder and by purifying commercial nickel carbonyl. The observed vapor pressure data were used in the derivation of the following equations which express the vapor pressure, P, of liquid nickel carbonyl and the sublimation pressure, P/sub s/, of the solid, respectively, as a function of the absolute temperature, T: log P = 7.88431578/T and log P/sub s/ 10.1897-2173/T. The average heat of vaporization is calculated to be 7.22 plus or minus 0.01 kcal per mole and the molecular heat of sublimation of Ni(CO)/sub 4/ is 9.94 plus or minus 0.11 kcal. Extrapolation to 760 mm Hg gives a boiling point of 42.2 deg C. The melting point of purified nickel carbonyl occurred at -17.2 deg C. The sensitivity of the melting point to the effect of impurities was demonstrated with commercial nickel carbonyl which melted at-19.4 deg C before purification, at --18.3 deg C after distillations at 0 deg C, and at -17.2 deg C after sublimation at -25 deg C. The vapor pressure of liquid nickel carbonyl at 0 deg C is of little value in evaluation of the purity of …