The fact that one of us was unable to find a medical reference to the volume of a liquid consumed by a patient in the act of swallowing, led us to attempt to obtain this information experimentally. These pilot-study findings are presented in the belief that such information may be of interest to those physicians who have occasion to treat cases of accidental ingestion of poisons. This information may also be of interest to those who have the responsibility for setting standards for labeling of hazardous substances. Most physicians and others interested in poison control agree that materials which are toxic enough to produce serious injury when consumed in an amount equivalent to one swallow are hazardous and should carry a precautionary label. Method The adult subjects consisted of 14 males and 10 females chosen at random. The adults were asked to swallow 175 cc. of cool water from a