24 MOTION OF THE JUICES OF THE ANIMAL BODY. 



attraction which the animal tissue exerts on the two ingredients of the mixed 

 liquid.* 



It is known from the experiments of SOEMMERING, that spirits of a certain 

 strength, inclosed in a bladder, which is opposed to the air, lose by evaporation 

 only water, and that at last anhydrous, or nearly anhydrous (absolute) alcohol is 

 left in the bladder. When strong spirits of wine are used, the bladder remains dry 

 externally ; when weaker spirits are employed, it becomes moist, and alcohol 

 evaporates with the water. In virtue of the unequal affinity of the bladder for 

 alcohol and for water, a complete separation is here effected. The water of the 

 mixture is absorbed and evaporates from the outside of the bladder ; the alcohol 

 remains in the bladder. As yet, we are acquainted with no substance which can 

 replace the bladder in this operation ; and indeed, the affinity of the gelatinous 

 tissues (membranes, &c.) for water must exceed that of all other animal tissues, 

 since a rise of temperature, of a few degrees only, suffices to enable water to 

 dissolve that tissue perfectly into a jelly. 



MEGNUS assumes, " that the particles of every solution, for example, of a salt in 

 water, adhere more strongly to each other than do those of the solvent, for 

 example, of water; consequently, the solution would be less fluid, and pass with 

 greater difficulty through very narrow openings, than water, if we take for granted 

 that the parietes of the openings act alike towards both. It would follow from 

 this, that, the more concentrated a solution, the less easily would it pass through 

 the same openings."! 



" Let us now try," pursues MAGNUS, " with the aid of these assumptions, 

 (which, as appears from the experiment Fig. 1, are perfectly accurate and 

 demonstrable for many saline solutions, although there are, according to the 

 researches of POISEULLE, a number of exceptions^) ) to explain the phenomena 

 of ENDOSMOSIS." 



" Both the brine and the water will penetrate into the pores of the bladder, and 

 brine will pass *rom the pores to the water, as well as water to the brine, in virtue 

 of their mutual attraction, till a complete equilibrium is established. Further, 

 since the force which attracts the water to the brine is exactly the same as that 

 which attracts the brine to the water, as much water as brine would pass through 

 the bladder, if both liquids could pass with equal facility through the pores. 

 Since, however, this is not the case, unequal forces are required to urge the two 

 liquids through the pores ; or with equal forces, unequal quantities of the two pass 

 through in equal times. There is consequently added more of that which passes 

 most easily, the water to the brine, than of the latter to the water, and the level of 

 both liquids must change, if no other force oppose this change. "( 3 ) 



According to this theory, brine and water exist in the pores of the bladder in a 

 state of motion, and the chemical affinity, which the particles of the brine have 

 for the particles of the pure water, and conversely, which the particles of water 

 have for those of salt, is considered as the cause of this motion. The unequal 

 velocity, which makes more water flow in a given time to the brine than brine or 

 salt to the pure water, is, according to MAGNUS, determined by the unequal 

 resistance which the substance of the bladder opposes to the passage of the two 

 liquids. 



Now, however narrow the tubes may be, in which molecules are set in motion 

 by an external force, it may always be assumed, that that part of the molecules, 

 which is immediately in Contact with the wall of the tube, either is not in motion, 

 or possesses only a snfall velocity, and the velocity of efflux must be a function of 

 the cohesion, and at all events not dependent on the wall of the tube. 



If now the efflux of the water on one side of the bladder is produced by the 

 attraction of the saline particles for the water, and the efflux of the brine on the 

 other side is produced by the attraction of the aqueous particles for the saline 



(*) Ann. de Ch. et de Phys. 3rd series, xxi. pp. 84 et seq. 

 ( 2 ) PoggendorfPs Annales, x. p. 164. 



* Effect of evaporation through a bladder in concentrated alcohol 

 t Views of Magnus on Endosrnosis. 



