TOWARDS THE SKIN AND LUNGS. 75 



sure, which is caused by the evaporation of the 

 fluids of the skin and lungs. 



The juices and fluids of the body distribute them- Effects of 

 selves, according to the thickness of the walls of the moist air, 

 vessels, and their permeability for these fluids, Ration on 6 

 uniformly through the whole body; and the influence 

 which a residence in dry or in moist air, at great 

 elevations or at the level of the sea, may exert on 

 the health, in so far as the evaporation may thus be 

 accelerated or retarded, requires no special explana- 

 tion ; while on the other hand, the suppression of 

 the cutaneous transpiration must be followed by a 

 disturbance of this motion, in consequence of which 

 the normal process is changed where this occurs. 



The pressure, which, in consequence of the eva- The force 

 poration, urges the fluids within the body to move fluids to- 



towards the skin, is, as may readily be understood, 

 equal to the difference of pressure acting on the 

 surface of the skin. 



From the experiment, Fig. 13, it is plain, that the skm * 

 when one of the two surfaces of bladder at the ends 

 of the tube Fig. 12, is exposed to atmospheric evapo- 

 ration, while the other end is moistened with water, 

 brine or oil, these liquids are rapidly absorbed by 

 the membrane, that is, are forced in by the external 

 atmospheric pressure, and it is not less obvious, that 

 the same thing takes place with the liquid with which 

 one of the two evaporating surfaces has been 

 moistened in the middle only ; while the evaporation 

 continues around the moistened spot. 



