The Determination of Ethyl Alcohol*

Of the various chemical methods described in the literature for the determination of ethyl alcohol (1) the majority are based upon the oxidation of the alcohol to acetic acid by means of potassium dichromate in the presence of a high concentration of sulfuric acid. Typical of these methods are the ones devised by Widmark (2) and by Nicloux (3). Widmark reports that it is not possible to calculate the amount of alcohol from the amount of dichromate used, for the oxidation does not lead exclusively to the formation of acetic acid; varying amounts of carbon dioxide and acetaldehyde are simultaneously produced. With solutions of pure alcohol ranging in concentration from 1.43 to 5.16 mg. per cc., he finds that 1 cc. of 0.01 N sodium thiosulfate solution corresponds to 0.1000 to 0.1241 mg. of alcohol. He adopts 0.113, the average of 54 determinations, as the factor to be used in the calculation of the number of mg. of alcohol present in a sample, but it is evident that considerable error is involved in the use of this factor. Furthermore, Widmark’s method is limited in its application to samples which contain only relatively small amounts of other volatile substances. Nicloux attempts to choose conditions such that a maximum yield of acetic acid and a minimum of carbon dioxide and acetaldehyde are produced. He reports a high degree of accuracy under the conditions which he finds optimum, but his method involves the use of three carefully prepared and standardized solutions and