The Hydrogen-Ion Concentration of Human Fæces

Howe and Hawk (1912) were the first to determine the exact hydrogen-ion concentration of human fjeces. They examined samples of fa}ces from three individuals and found that the reaction of the material examined by them was always alkaline, varying with the different subjects and conditions from pH 7.01 to 8.77. Nelson and Williams (1916) recorded that 29 of the 30 individuals examined by them passed faeces which were acid in reaction and Rettger and Cheplin (1921) reported similar observations. Robinson (1922) found the pH of the human faeces to range between 7.0 and 7.5. The investigations reported in the literature have been scanty, often based on an inadequate number of observations, and the results conflicting. Except for the observations of Knowles, Napier and Das Gupta (1923) who determined the reactions of dysenteric stools no published data are available on the reaction of the feces of healthy individuals living on different diets and exposed to tropical conditions. Freshly-passed stools were collected in sterilized dry bed-pans and care was taken to prevent 'admixture of urine with the specimen. Suspensions of the stool were made in distilled water adjusted to pH 7.0. The suspensions Were standardized to a density which allowed