Introduction. The compound was prepared by passing dry HC1 gas into an ethereal solution of the lactam. The resulting precipitate was filtered, washed with dry ether and recrystallized from dry acetone. Crystals for X-ray examination were sealed in capillaries to protect them from moisture.Intensities from a crystal of dimensions 0.40 × 0.35 × 0.45 mm were collected on an automated Hilger-Watts Y290 diffractometer with Mo Ks radiation (2 = 0-71069 /~,/z = 4"03 cm-1) monochromatized by reflexion from graphite. In the 0 range out to 25 ° all reflexions were measured, in the range 25°<0<30 ° only those significantly above background. In the course of the measurements intensity variations for some reflexions occurred. Although the more obvious possible sources of fluctuation (movement of crystal, insta-