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The oxygen content of beryllium metal was found by irradiating samples with 14-5-MeV neutrons and measuring the 7.4-second nitrogen-1 6 activity produced in the reaction 1 6 0 (n,p) 1*N. Oxygen contents in the range 0.01 to 2-0 per cent. have been measured by this method. As little as 0.001 per cent. of oxygen can be detected, provided that the intensity of short-lived reaction products from other impurities is sufficiently low.The identification and determination of other impurities in the metal are discussed.

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Energies of up to 3 kJ g−1 were deposited in thin aluminium foils by means of a pulsed electron beam with a duration of 35 ns. The subsequent expansion of the foils was observed using high-speed photography and compared with that predicted from numerical solutions of the equations of motion. The velocities observed were about double those calculated. The limitations of the expansion equation of state used in the calculations are discussed.The variation of the spall strength of aluminium with temperature was derived from the measured energy deposition thresholds to spall foils of different thicknesses. It was found to fall from 12·5×108 N m−2 (12·5 kbar) at 350°C to about 4×108 N m−2 at 600°C with some evidence for a strength in the solid-liquid phase of a fraction of a kilobar.