LIQUIDS MIXING THROUGH A MEMBRANE. 41 



alone, the volume of the liquid would not change. 

 The mixture would take place, but no water would 

 flow out. 



A bladder, saturated with water, when brought 

 in contact with alcohol, shrinks together, a part of 

 the water separates from the animal matter, but 

 there always remains in the bladder a certain 

 amount of water, corresponding to its attraction for 

 the bladder and for the alcohol ; just as the solutions 

 of many salts which have a strong attraction for 

 water (such as metaphosphate and acid phosphate of 

 soda), and are insoluble in alcohol, are separated by 

 the addition of alcohol into two strata of liquid, 

 the heavier of which is a more concentrated solu- 

 tion of the salt in water, containing a little alcohol, 

 while the other, the lighter, is an aqueous liquid 

 containing much alcohol. The alcohol and the salt 

 divide between them the water of the solution. 



When we add, to a mixture of equal parts of Action of 

 acetone and water, a certain quantity of dry frag- 



ments of chloride of calcium, the first fragments 

 which are added deliquesce and dissolve entirely in and water ' 

 the mixture. But if we go on adding the salt, a 

 separation soon occurs, two strata of liquid are 

 formed, of which the upper contains acetone and 

 water, the other is an aqueous solution of the 

 chloride with a little acetone. If we add still more 

 of the chloride, water is abstracted from the acetone 

 of the upper stratum, and when a proper quantity 



