Hickinbottom1,2 finds unsaturated alcohols are formed in the treatment with per-acids of 2:4:4 trimethyl pentene-1 (I) and -2 (II) and also in the acid hydrolysis of the epoxide (IV) derived from the latter olefin. The object of this note is to show that these results do not, as Hickinbottom claims, throw any light on the double-bond shift observed in the air oxidation of some organic compounds, but can readily be accounted for by the formation of ionic intermediates. The action of the per-acids gives initially the epoxides (III and IV) by addition of oxygen to the double bond3.