38 MOLECULAR ATTRACTION. L.ECT. II. 



the rise of the liquid was more rapid in the tube placed in 

 a vacuum than in one which was contained in the air. 



Imbibition limited. It may be asked whether, by the 

 action of imbibition, a liquid can rise to an unlimited height. 

 It would at first sight appear, that a column of sand, of ashes, 

 or other pulverized bodies, one end of which is immersed 

 in a liquid constantly maintained at the same level, should, 

 by the force of imbibition, elevate the liquid to any height 

 till the whole column has imbibed. Indeed, if we con- 

 sider separately the action of each of the layers forming 

 the column, we may suppose that after the imbibition of 

 the first layer in contact with the liquid, the particles of the 

 second layer immediately above will deprive the first of a 

 portion of its water, and the latter will re-obtain from the 

 liquid mass the amount it had lost. By repeating this rea- 

 soning for all the successive layers of the column, we 

 arrive at the conclusion that each takes up the same amount 

 of liquid as if it had acted separately, and thus, if the level 

 of the liquid be kept constantly at the same height, the en- 

 tire column, however long it may be, will imbibe. But 

 experience does not confirm this reasoning ; the liquid 

 rises at first rapidly, then the ascending movement slackens, 

 and at a certain height the liquid remains stationary. This 

 fact cannot be ascribed to the evaporation in the upper 

 layers of the column; for water rises to the same height 

 in a column of sand, whether it be surrounded by the va- 

 pour of water, or by dry air. I can only account for it by 

 admitting the existence of small canals in the whole length 

 of the column of powder, and then, consequently, capillary 

 action, as well as the adhesion of the liquid to the surface 

 of the grains of sand, will intervene. 



Agency of Imbibition in living Beings. It is impossible 

 not to perceive that imbibition plays an important part in 



