A single-crystal neutron-diffraction investigation of sodium thiosulphate pentahydrate, Na2S203.5H20, has been made with three sets of zonal data. The structure was refined by least-squares techniques, with individual temperature factors, to an R value of 8.2%. The geometry of the $203 group and sodium-oxygen framework agree with those of X-ray studies. The positional parameters of some of the atoms differ from those p3stulated from the X-ray and nuclear magnetic resonance studies. The O-H and H-H bond distances and the H-O-H valence angle of all the five water molecules were found to be normal. The hydrogen-bond scheme falls into four classes: two strong water-thiosulphate oxygen, two weak water-thiosulphate oxygen, two water-water, and three water-sulphur hydrogen bonds. From the geometry of its surroundings one of the hydrogen atoms H(9) may be regarded as not participating in hydrogen bonding.

Einsteinium-253 nuclei were oriented at low temperatures in a neodymium ethylsulfate lattice. From the temperature-dependent a-particle angular distribution a nuclear magnetic moment )pl = {2. 7 +1. 3}p& was deduced. From the values for the angular distribution function at the lowest temperatures it was possible to test the predictions of the Mang shell-model theory for the relative phases and amplitudes of the n-partial waves. As predicted, the waves of angular momentum L =0 and 2 are in phase, and the L, = 0 and 4 waves are out of phase. The predicted wave amplitudes are in error, especially that of the I =4 wave. The predicted relative intensities {which are proportional to the amplitudes squared) for the S, D, and G waves are 1.000:0. 179:0. 0052, whereas the relative intensities that best fit the experimental angular distribution are 1.000:0. 216:0. 0078.

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