Professor J. L. B. Smith

between NO, and either the solvent or impurities contained therein. Radicals described as NH 3 -, C,H,+ and allyl alcohol diradicals are without doubt other species than these, and the presence of a hyperfine splitting from 129 Xe in irradiated OF 4 is certainly surprising ! It would scarcely seem nece~:>t-a"'ry to illustrate spectra for polycrystalline diphenylpicrylhydrazyl, or indeed for aqueous Mn2+, but to find both these spectra referenced as "unpublished results" is quite astonishing.