MEMBRANES WHEN STREWED WITH SALT. 13 



because the animal tissue has less attraction for the 

 mixture of alcohol and water than for pure water 

 alone. The alcohol without becomes diluted, the 

 water within becomes mixed with a certain propor- 

 tion of alcohol, and this exchange is only arrested 

 when the attraction of the water for the animal 

 tissue, and its attraction for alcohol, come to counter- 

 poise each other. 



If we regard a piece of skin or bladder or fibrine, 

 as formed of a system of capillary tubes, the pores 

 or minute tubes are, in the fresh state, filled with a 

 watery liquid, which is prevented from flowing out 

 by capillary attraction. 



But the liquid contained in these capillary tubes 

 flows out of them as soon as its composition is 

 altered by the addition of salt, alcohol, or other 

 bodies. 



If we lay together, one over the other, two por- 

 tions of bladder, saturated with solution of salt of 

 sp. g. 1*204, and over the upper one another piece 

 of bladder of equal size, saturated with water, and 

 if we allow them to remain thus, without pressure, 

 we find, after some minutes, when the two pieces 

 saturated with solution of salt are separated, that 

 drops of saline solution appear between them, of 

 which no trace could previously be perceived. If 

 the piece of bladder saturated with water contained 

 5 volumes of water, and the next piece 3 volumes 

 of saline solution, there must be produced, by the 

 mixture of both, 8 volumes of diluted saline solu- 



