86 ABSORPTION AND EXHALATION. L.ECT. IV. 



the vein also, with water. I immerse a portion of the vein 

 in water, acidulated with sulphuric or hydrochloric acid. 



Fig. 5. 



Apparatus to illustrate Physical Absorption. 



At first the liquid in the bottle gives no indications of the 

 presence of the acid ; but after a certain time it does. If, 

 instead of waiting some time, and leaving the liquid in re- 

 pose, I open the stop cock, I can immediately detect the 

 presence of the acid in the liquid which flows out ; but in 

 the bottle it is not yet discoverable. That which happens 

 with a portion of vein, will take place in the same way with 

 the arterial trunk, and with tubes of clay, pasteboard and 

 wood. If the acidulated solution be contained in the in- 

 terior of the vein ; and if into the liquid of the basin, in 

 which the vein is immersed, we pour some tincture of lit- 

 mus, the same phenomenon is observed ; that is, the acid 

 will pass out through the coats of the vein, with a facility 

 proportionate to the velocity of the current. The conditions 

 of the phenomenon are always the same : two liquids 

 miscible with each other, and separated by a membrane 

 capable of imbibing them, and the movement of the inter- 



