The relation between sweat rate and weight loss when sweat is dripping off the body.

1. The relation between the rate of sweat production, S, and the rate of weight loss, W, has been examined under conditions in which the rate of evaporation was small.2. S could be found from W provided that a film of liquid was maintained over the skin surface. This could be achieved initially by immersing the subject in water containing detergent. Thereafter the film was maintained so long as the rate of weight loss exceeded about 10 g/min.3. When the rate of weight loss was changing and the rate of evaporation was constant, S could be calculated as W + 2.5 W.4. When the subject was constantly sprayed with water while being weighed, the correction for W became negligible. In this case there was no lower limit to the sweat rate which could be measured, but spraying considerably reduced the accuracy of the measurement.5. The output of sweat from a ventilated capsule on the forearm correlated well with estimates of central sweating drive based on weight measurements corrected for hidromeiosis.