The ketonic acid, C9H14O3, obtained by the rearrangement of santenonequinone in presence of sulphuric acid has now been definitely identified as 2 : 3-dimethylcyclohexan-1-one-4-carboxylic acid by direct synthesis of this acid, as well as the isomeric 3 : 6-dimethylcyclohexan-1-one-4-carboxylic acid by unambiguous methods. Incidentally it has been shown that the Dieckmarin condensation of ethyl β-methylpentane-\(\beta\gamma\epsilon\)-tricarboxykite leads to the formation of ethyl 3-methyicyclohexan-l-one-4 : 6-dicarboxylate and not the isomeric ester ethyl 3-methyl-cyclohexan-1-one-2 : 4-dicarboxylate.