[1956] Some Aspects of the System Uranium Trioxide-Water. 3531 683. Some Aspects of the System Uranium Trioxide-Water. By J. K. DAWSON, E. WAIT,K. ALCOCK,and D. R. CHILTON. Uranium trioxide in contact with water at about 180' gives an ortho- rhombic hydrate U0,,0.8H2O with the cell dimensions a = 10-23& 0-01 b = 6