FOR DIFFERENT LIQUIDS. 49 



a very thin membrane, saturated with concentrated 

 brine by steeping for 24 hours, and if we dry the 

 outer surface of the membrane carefully with 

 bibulous paper, and now pour a few drops of. pure 

 water into the tube so as just to cover the inner 

 surface of the membrane, the outer surface is seen 

 in a few moments to be covered with minute drops 

 of brine ; that is, brine flows out of the pores of 

 the bladder. 



A thick ox-bladder, saturated with oil, exhibits 

 the same phenomenon in contact with water. The 

 oil is expelled from the pores of the bladder by the 

 water, which occupies its place. 



When the bladder is brought in contact with Explana- 

 tion. 

 pure water, it takes up a certain quantity of that 



liquid. If its pores are previously filled with brine, 

 and if we cover one side of it with pure water, the 

 water mixes with the brine in the pores of the 

 bladder ; and on the side next the water there is 

 formed a diluted brine, which, being in contact 

 with a stratum of pure water, mixes with it, and 

 in this way the successive strata of water receive, 

 from the bladder outwards, a certain quantity of 

 salt. 



In the interior of the bladder, there are formed 

 in like manner, towards the outer surface, mixtures 

 of unequal saline strength. If we suppose the 

 bladder to consist of several strata, all these strata 

 receive, from the surface in contact with the water, 

 a certain quantity of water ; the outer stratum, in 



E 



