INSENSIBLE PERSPIRATION. 39 



by subtracting- the loss occasioned by the" lungs, the 

 remainder of course exhibited the amount carried 

 off by the skin. He attended minutely also to the 

 collateral circumstances of diet, temperature, &c. ; 

 and allowance being made for these, the results at 

 which he arrived were the following: 



The largest quantity of insensible perspiration 

 from the lungs and skin together amounted to thirty- 

 two grains per minute ; three ounces and a quarter 

 per hour ; or five pounds per day. Of this the cu- 

 taneous constituted two-thirds, or sixty ounces in 

 twenty-four hours. The smallest quantity observed 

 amounted to eleven grains per minute, or one pound 

 eleven and a half ounces in twenty-four hours, of 

 which the skin furnished about twenty ounces. The 

 medium or average amount was eighteen grains a 

 minute, of which eleven were from the skin, making 

 in twenty-four hours about thirty-three ounces. When 

 the extent of surface which the skin presents is con- 

 sidered, these results do not seem extravagant. But 

 even admitting that there may be some unperceived 

 source of fallacy in the experiments, and that the 

 quantity is not so great as is here stated, still, after 

 making every allowance, enough remains to demon- 

 strate that exhalation is a very important function 

 of the skin. And although the precise amount of 

 perspiration may be disputed, still the greater num- 

 ber of observers agree that the cutaneous exhala- 

 tion is more abundant than the united excretions 

 of both bowels and kidneys ; and that, according as 

 the weather becomes warmer or colder, the skin 

 and kidneys alternate in the proportions of work 

 which they severally perform ; most passing off by 

 the skin in warm weather, and by the kidneys in 

 cold, and vice versa. The quantity exhaled increases 

 after meals, during sleep, in dry warm weather, and 

 by friction or whatever stimulates the skin ; and di- 

 minishes when digestion is impaired, and in a moist 

 atmosphere 



