QUANTITY OF THE PERSPIRATION. 793 



these two totals, gave, for the amount of cutaneous and pulmonary 

 exhalation together, fths of the total loss of weight of the body. (San- 

 torini.) By enveloping the body in an impermeable oil-silk bag, so as 

 to condense and retain the water of the cutaneous exhalation, it was 

 found that, in an adult, about 30 oz. are daily exhaled by the skin, 

 whilst at the same time, 15 oz. are given off by the lungs, making a 

 total daily loss, by both skin and lungs, of 45 oz. (Seguin.) The total 

 loss has, however, been estimated at 45J oz. in the autumn, 44 oz. in 

 summer, and 37 oz. in spring, in a person under the average size. (Dr. 

 Dalton.) Other estimates give an average total loss of 57 oz., 51 oz. 

 in the winter, and 63 oz. in the summer. 



The quantity of perspiration exhaled by different parts of the body 

 differs widely. Its general quantity is influenced both by intrinsic and 

 extrinsic conditions ; thus it is augmented by increased vascularity of 

 the skin, by a higher temperature of the body, by a quicker circulation, 

 and therefore by exercise and effort generally. Perspiration may also 

 be induced by additions to the clothing or covering of the body, and 

 likewise by breathing in a confined space; it is also increased by pe- 

 culiar conditions of the nervous system, as by certain depressing emo- 

 tions and syncope, all of which tend to relax the skin and its bloodves- 

 sels. It is, on the other hand, diminished or almost entirely arrested 

 in febrile conditions and certain forms of excitement, and, it is said, 

 also by the use of coffee. It is increased by taking food generally, but 

 more particularly after dinner. The secretion is stated to be most 

 active about noon, and least so in early morning. It is also augmented 

 during sleep. 



Of the external conditions which modify the quantity of the perspi- 

 ration, by far the most important are the temperature and hygrometric 

 condition of the atmosphere. Thus, in warm air, which increases the 

 activity of the cutaneous circulation, the perspiration is increased, 

 whilst cold air has the opposite effect; again, dry air increases the 

 perspiration, whilst damp air diminishes it. Simple warmth acts by 

 increasing the vascular action through the skin ; whilst dry ness oper- 

 ates by maintaining a constant evaporation from the cutaneous sur- 

 face; on the other hand, cold diminishes the vascularity of the skin, 

 and dampness of the air impedes evaporation. The combination of 

 moisture with heat, however, increases the exhalation by the skin, 

 which then appears in large drops. Motion in the air, whether warm 

 or cold, dry or moist, increases the relative amount of perspiration, by 

 carrying it off more quickly. The perspiration is said to be dimin- 

 ished by increased atmospheric pressure. This excretion is also aug- 

 mented by large quantities of drinks, especially when taken warm ; by 

 so-called sudorific medicines, such as nitre, Dover's powder, and vine- 

 gar; by electricity; and also by hot baths, whether water-baths, vapor- 

 baths, or hot-air baths, especially when, as in the Turkish and Roman 

 baths, friction and shampooing are superadded. Certain curious local 

 sweatings have been noticed, affecting the head alone, or the feet and 

 hands, or even one side of the face only, phenomena which probably 

 are due to some loss of power in the vasi-motor nerves of the arteries 

 of those parts, giving rise to dilatation of the vessels, increased vascu- 



