On periodic sweating from the human skin during rest and exercise

The rhythmic variations in the water evaporation rate (gm ² h ¹1 from the dorsal side of the forearm have heen studied. The evaporaition rate is estimated by calculating the difference between the vapour pressures at two distinet points on a line perpendicular to the evaporative surface. Using autocorrelation technique it is found that the evaporation rate is periodie with a period of around 0.7 s. This value is consistent. al rest as well as prior to profuse sweating in exercise. for all the subjects included in the investigation. During profuse swesting the period becomes slightly longer. It is suggested that the variations in the evaporation rate reflect the periodie activity in the sudomotor nerves.