Abstract
A short historical review is given of the work of previous investigators upon the distribution of ammonia between water and chloroform and the influence of ammonium chloride upon this distribution. An experimental procedure is described for the accurate determination of the partition coefficient of ammonia; results are given for its value using chloroform and pure water, chloroform and aqueous solutions of ammonium chloride. from these determinations, the activity coefficient of the undissociated portion of ammonia in aqueous solution and in aqueous ammonium chloride solution, is calculated, The variation of this function with ionic strength is discussed and its behaviour compared with that indicated by recent activity theories.