A method is described for the determination of metallic beryllium and beryllium carbide in beryllium metal. The beryllium metal is dissolved in potassium hydroxide solution at a controlled rate of solution. The liberated hydrogen and methane are burned with copper oxide in an atmosphere of nitrogen. The water and carbon dioxide formed are absorbed in magnesium perchlorate and ascarite, respectively, and determined by weighing. The metallic beryllium is calculated from the water, corrections being made for any calcium or aluminum present as impurities that also liberate hydrogen in caustic solution; in case beryllium carbide is determined, a correction may also be made for the water formed by the combustion of methane. The beryllium carbide is calculated as Be2C from the carbon dioxide formed. No methods were found in the literature for the simultaneous determination of metallic beryllium and beryllium carbide in beryllium metal in the presence of beryllium oxide. The similarity of aluminum and beryllium in a number of their reactions suggested a study of the work published about the determination of both metallic aluminum and metallic beryllium in the presence of the oxides. Metallic aluminum in aluminum metal or powder may be estimated by dissolving the metal in alkali solution [1, 2] 2 or in hydrochloric acid [3], and then measuring the volume of the liberated hydrogen or weighing it as water after combustion, information on gas evolution methods as used for industrial products may be found in the literature [4 to 8]. Two methods of special interest are described, one consisting of reduction of ferric ion to the ferrous state while dissolving the sample in acid, followed by titration [9], and the other involving the passage of hydrochloric acid gas over the metal at an elevated temperature, followed by determination of chloride in the sublimate [10]. A correction for iron is made in both cases. Similar procedures based upon reduction of ferric iron by aluminum metal in the presence of acid or dealing with volatilization of aluminum chloride have been discussed [11 to 17}<. The hydrogen evolution methods for the determination of metallic aluminum cited above do not describe a procedure for the estimation of and correction for aluminum carbide. Yu. A. Klyachko and M. A. Barkov [18], in an effort to establish conditions for the determination of the total free and combined carbon in aluminum, burned the methane that was formed in the reaction of aluminum carbide and an alkali solution. For the estimation of microgram quantities of carbon in aluminum, a conductometric determination of the absorbed carbon dioxide has been developed [19]. Before discussing some attempts to determine metallic beryllium and beryllium carbide by methods