1. W. J. Potts, J. Chem. Phys. 20, 810 (1952).JCPSA60021-9606
2. L. B. Clark, doctoral thesis, University of Washington, 1963.
3. E. E. Barnes, doctoral thesis, University of Washington, 1960.
4. We wish to thank Professor A. Novick for his generosity in loaning us this instrument.
5. This is shown to be consistent with the theory developed later in Appendix III.