PERSPIRATION AND SWEAT. 519 



ish. It is not precipitated when supersaturated with acetic acid, 

 and prussiate of potash does not throw down any thing from the 

 acid liquor, but the infusion of nut-galls throws down a copious 

 precipitate. 



The portion insoluble in potash when burnt exhales the smell 

 of burning animal matter, and leaves a very little alkaline ash. 

 Boiled in a very concentrated solution of caustic potash, it gives 

 the liquor a brownish-yellow colour, and emits the smell of horn 

 subjected to the same treatment. A little matter falls, which is 

 a compound of the dissolved substance and potash. It is soluble 

 in water. Thus, the substance in cerumen, which resists the ac- 

 tion of all the reagents except very concentrated caustic potash, 

 possessed many of the properties of horn, though it differs from 

 that substance in several of its characters. 



From these experiments of Berzelius, it appears, that cerumen 

 is composed of, 



Stearin. Yellow matter soluble in water. 



Elain. Albumen (uncoagulated). 



Otin. Albumen (coagulated). 



Lactates of lime and potash or soda. 



CHAPTER XIX. 



OF PERSPIRATION AND SWEAT. 



THAT a quantity of matter is constantly emitted from the skin 

 has been long known, as this matter in most cases is dissipat- 

 ed as fast as it is thrown out of the body, and of course without 

 being perceived, unless peculiar contrivances be used to detect it ; 

 it has got the name of insensible perspiration, 



Many experiments have been made to determine the quantity 

 of matter perspired through the skin. For the first set and not 

 the least remarkable, we are indebted to Sanctorius, who con- 

 tinued them for no less than thirty years. According to him, 

 the average quantity of matter perspired through the skin in a 

 natural day amounts to not less than 50 ounces.* A similar 

 set of experiments was afterwards made in France by Dodart, 

 and in England by Keil. According to Dodart the perspira- 



* See Quincy's Medicina statica, p. 54. 



