Author to whom questions and requests for reprints should be directed:   present address:  Department of Chemistry and Chemical Engineering,  Royal Military College of Canada   P.O. Box 17000, Station Forces   Kingston, Ontario   Canada     K7K 7B4   Phone: (613) 541-6000 ext. 6360   Fax: (613) 542-9489   E-mail: fischer-f@rmc.ca