of those estimated for the hydroxymercuration of olefinic compounds by other organomercurial ions from measurements on the rates of exchange of olefins with oxymercurials.9 Also pertinent to the present theme are recent direct observations of the acid-induced cleavage of diacetonylmercury10 and of the methoxymercuration of an aliene by organomercury(II) ions.11 Finally, the results of these studies yield information, not previously available, about the effects of the systematic variation of R in the series of RHg+ ions examined, both on the equilibrium constant (K3) of the oxymercuration reaction 3 and on the rate constant (/c4) of the acid-promoted deoxymercuration reaction 4. The data in Table I reveal a marked parallel between the variations of the two constants, each of which appears (9)