This investigation was undertaken for the purpose of devising a satisfactory method for the determination of sodium in the presence of the other elements usually associated with it, that is, the members of the alkali and alkaline earth groups. It was especially desired to find a method suitable for the determination of small amounts of sodium, since this is the usual problem met with in analytical practice. The writer wishes to acknowledge his indebtedness to Prof. C. W. Foulk for his kindly advice and criticism during the progress of the investigation.