1911 Encyclopædia Britannica/Perspiration

PERSPIRATION (Lat. per, through, and spirare, to breathe), the excretion of sweat from the sweat-glands of the skin. Sweat is a clear colourless neutral or slightly alkaline fluid containing 2% of solids. Under pathological conditions, sugar urea and other substances are found. The secretion of sweat is constantly going on, the activity of the sweat-glands being under control of the central nervous system. The only function of sweat is the regulation of the heat discharge from the body. The chief morbid conditions of the sweat-glands are excessive sweating (Hyperidrosis) and foetid sweating (Bromidrosis). Excessive sweating is a symptom observed in various diseases, such as tuberculosis and rheumatic fever, but it may exist apart from such conditions, and either be general, affecting the whole body, or confined to a part, such as the axillae, head, hands, feet, or, as in some rare instances, the one half of the body. Excessive perspiration may often be prevented by the cold bath, and by tonics, such as iron, quinine, strychnia, &c. Locally, the use of astringent lotions of vinegar or a weak solution of lead will also be of service. Foetid sweating most frequently affects the feet, specially in those who have much fatigue, and is apparently due to rapid decomposition in the perspiration which has saturated the stockings; these should be frequently changed and the feet washed several times a day, dried carefully, and dusted with some antiseptic powder.