PROGRESS in instrumental methods of analysis during the past 10 years, particularly in the new field of gas chromatography, has provided the chemist with powerful tools for the separation and identification of complex mixtures. Nevertheless, it is often advantageous to fractionate the mixture prior to gas chromatography analysis in order to simplify the task of isolation and identification of single components. The oil of the hop (Humulus lupulus L. var. Bullion) isolated by the method of Wright and Connery1 has been fractionated as follows: hydrocarbons were selectively separated from oxygenated compounds through alumina or silica-gel columns using light petroleum ether as eluant2. Esters and ketones were separated from alcohols by selective elution from a neutral alumina column using absolute ether as eluant. Esters were subjected to methanolysis using mineral acid as catalyst, and the resulting methyl esters separated from the freed alcohols, as described here. Compounds having a straight chain of seven carbons or more were separated from shorter or branched chain compounds by formation of crystalline adducts with urea in methanol3. Carbonyls were extracted from mixtures containing other oxygenated compounds by the Girard method4,5. Unsaturated compounds were separated from saturated compounds by bromination in carbon tetrachloride6. Unsaturated compounds having a conjugated double-bond system were separated from others by the Diels–Alder reaction7.