PERSPIRATION. 331 



It is easy to understand, therefore, that a very large quantity of 

 fluid may be supplied from so extensive a glandular apparatus. It 

 results from the researches of Lavoisier and Seguin 1 that the ave- 

 rage quantity of fluid lost by cutaneous perspiration during 24 

 hours is 13,500 grains, or nearly two pounds avoirdupois. A still 

 larger quantity than this may be discharged during a shorter time, 

 when the external temperature is high and the circulation active. 

 Dr. Southwood Smith 2 found that the laborers employed in gas 

 works lost sometimes as much as 3J pounds' weight, by both cuta- 

 neous and pulmonary exhalation, in less than an hour. In these 

 cases, as Seguin has shown, the amount of cutaneous transpiration 

 is about twice as great as that which takes place through the lungs. 



The perspiration is a colorless watery fluid, generally with a 

 distinctly acid reaction, and having a peculiar odor, which varies 

 somewhat according to the part of the body from which the speci- 

 men is obtained. Its chemical constitution, according to Ansel- 

 mino, 3 is as follows : 



COMPOSITION OF THE PERSPIRATION. 



Water 995.00 



Animal matters, with lime ........ .10 



Sulphates, and substances soluble in water .... 1.05 



Chlorides of sodium and potassium, and spirit-extract . . 2.40 



Acetic acid, acetates, lactates, and alcohol-extract . . . 1.45 



1000.00 



The office of the cutaneous perspiration is principally to regulate 

 the temperature of the body. "We have already seen, in a preced- 

 ing chapter, that the living body will maintain the temperature of 

 100 F., though subjected to a much lower temperature by the 

 surrounding atmosphere, in consequence of the continued genera- 

 tion of heat which takes place in its interior ; and that if, by long 

 continued or severe exposure, the blood become cooled down much 

 below its natural standard, death inevitably results. But the body 

 has also the power of resisting an unnaturally high temperature, 

 as well as an unnaturally low one. If exposed to the influence of 

 an atmosphere warmer than 100 F., the body does not become 

 heated up to the temperature of the air, but remains at its natural 

 standard. This is provided for by the action of the cutaneous 

 glands, which are excited to unusual activity, and pour out a large 

 quantity of watery fluid upon the skin. This fluid immediately 



1 Milne Edwards, LeQons sur la Physiologie, &c., vol. ii. p. 623. 



2 Philosophy of Health, London, 1838, chap. xiii. 



3 Simon. Op. cit., p. 374. 



