56 MECHANISM OF ABSORPTION. 



exterior of that tube will be absorbed ; but as to the 

 relative influence of the stream and the membrane 

 in accomplishing that end, we are left altogether in 

 the dark. He referred the whole of the transmit- 

 ting power to the membrane, but the same experi- 

 ment will, I think, prove equally well the influence 

 of the stream in increasing that power. 



It has long been known that a fluid, while tra- 

 versing any porous vessel, will draw in a consider- 

 able quantity of air, which is liberated when the 

 fluid is again at rest. 



I now proceed to quote an experiment from Sir 

 John Leslie's " Elements of Natural Philosophy," 

 vol. i. p. 364:- 



If a cylinder, "one inch in diameter, and three 

 inches long, be fitted into an orifice at the bottom of 

 a cistern, and on its upper side, at the distance of 

 half an inch from its origin, a narrow arched glass 

 tube inserted, the long end of which is carried down 

 to a basin of water, three feet below the insertion of 

 the other end, when a stream traverses the cylinder 

 with a velocity of nine feet per second, it will raise 

 the water up the glass tube to the height of two 

 feet, and if the tube be shortened within that limit, 

 the basin will in a short time be emptied of the 

 stagnant fluid." I have now several times repeat^ d 

 this experiment, and with a rapid stream the results 

 were always in accordance with the above statement. 

 Having filled a wine-glass with coloured fluid, and 

 having connected its contents (by means of a bent 

 tube twelve inches long) with the interior of a pipe 

 half an inch in diamoter, I found that the glass was 



