64 INFLUENCE OF THE CUTANEOUS 



gradually to rise; and in three or four days it 

 increases by from ^ to ^ of its volume, exactly as 

 the tube had been closed with a very thick 

 membrane. 



Influence of the cutaneous evaporation on the motion 

 of the fluids of the animal body. 



influence of When a tube, about 30 inches long, bent in the 



ous evapor- form of a knee, and widened at one end, is tied over 



motion of e at that end with a piece of moist ox-bladder, the 



fluid's 11 bladder now thoroughly dried, and the tube filled 



with mercury and inverted, so that the open narrow 



end stands in a cup of mercury, the mercury in the 



tube falls to about 27 inches (Hessian), and remains, 



if the bladder have no flow, at that height, rising 



and falling as the mercury does in a barometer. 



No air passes through the dry bladder into the 

 Torricellian vacuum thus produced. When, by 

 proper manipulation, we have allowed to pass out as 

 much as can be removed of the air still contained in 

 the tube, we have, in this arrangement, a barometer, 

 containing no more air than would be found in one 

 made with a similar tube hermetically sealed at the 

 wide end, provided the mercury in the latter had not 

 been boiled in the tube to expel the last traces of 

 air. By the desiccation of the bladder, its pores, 

 which allowed a passage to water, brine, oil, or even 

 mercury, have obviously been closed by the adhesion 

 of the successive layers of membrane, which per- 

 haps cross each other, so that the bladder is not more 



