At least twice within the last few years it has been reported that pure ethyl ether is not an anesthetic, and that the physiologic action ordinarily attributed to this compound is due to impurities contained in the commercial material. According to Cotton, 1 carbon dioxid may be the active agent in some ethers; but this investigator reported that he had obtained the best results by the use of ether containing ethylene and possibly another gas of unrecognized nature. According to Wallis and Hewer, 2 ketones are the most important impurities, though they state that the anesthetic action of ether is enhanced by treating it with carbon dioxid and ethylene. The lack of chemical details in the papers of Cotton and of Wallis and Hewer is unsatisfactory. The foregoing statements appeared to warrant further investigation. All commercial ether today is manufactured by the Williamson sulphuric acid-alcohol process. The reaction is such