PERSPIRATION AND SWEAT. 



water trickled down. By keeping his hand thus enclosed for an 

 hour, he collected 30 grains of a liquid which possessed the 

 properties of water. On repeating the same experiment at nine 

 in the evening (thermometer 62), he collected only 12 grains. 

 The mean of these two trials is 21 grains.* But as the hand is 

 more exposed than the trunk of the body, it is reasonable 

 to believe that the perspiration from the trunk is greater than 

 from the hand. Let us therefore take 30 grains per hour as the 

 mean, and let us suppose with Cruikshanks, that the hand is one- 

 sixtieth of the surface of the body. The total perspiration in twenty- 

 four hours would amount to 43,200 grains, or 90 ounces troy. 

 This being much more than the quantity stated by Lavoisier and 

 Seguin, or even than the amount ascertained by Sanctorius, we 

 must conclude that more matter is perspired from the hand than 

 the trunk, provided Cruikshanks' estimate of the ratio between 

 the surface of the hand and the body be not erroneous. 



He repeated the experiment again after hard exercise, and col- 

 lected in an hour 48 grains of water. He found that this aque- 

 ous vapour pervaded his stocking with ease, and that it made its 

 way through a shamoy leather glove, and even through a leather 

 boot, though in much smaller quantity than when the leg want- 

 ed that covering.f 



It is evident from these experiments of Cruikshanks just stat- 

 ed, that the matter perspired consists chiefly of water. But it 

 follows also, from his experiments, that carbonic acid gas is 

 evolved from the skin. The air of a glass vessel in which his 

 hand and foot had been confined for an hour contained carbo- 

 nic acid gas ; for a candle burnt dimly in it, and it rendered 

 lime-water turbid.J M. Jurine found that air which had remain- 

 ed for some time in contact with the skin consisted in a great 

 measure of carbonic acid gas. The same conclusion follows 

 from the experiments of Ingenhousz and Milly.|| Trousset ob- 

 served that gas was separated copiously from the skin of a pa- 

 tient of his while bathing.1I 



Besides water and carbonic acid, the skin emits also an 

 odorous substance. That every animal has a peculiar smell is 

 well known. The dog can discover his master, and even trace 



* On Insensible Perspiration, p. 68. f H>id. ? 82. 



\ On Insensible Perspiration pp. 70 and 81. Encyc. Meth. Med. i. 515. 



U Encyc. Meth. Med. p. 511. ^ Ann. de Cbim. xlv. 73. 



