1. Department of Physical Sciences, Newcastle College of Advanced Education, P.O. Box 84, Waratah, N.S.W., Australia 2298
2. Department of Chemistry, University of Newcastle, Shortland, N.S. W., Australia 2308
3. Department of Experimental Pathology, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T., Australia 2600