On the Physical Cause of Endosmosis. 281 



positively, passes through the membrane to the water electrified 

 negatively, gradually increasing the volume of the latter. 



The exact resemblance of this effect to that of endos- 

 mosis produced by the difference in the density of the 

 liquids, led me to consider the latter phenomenon as the 

 result of an electric impulsion. The electricity appeared to 

 me to be produced by the difference of density in the two 

 liquids separated by the membrane. Further reflection has, 

 however, induced me to abandon this idea: the body of water 

 in contact with the positive pole disengages oxygen in a state 

 of elasticity ; this water, therefore, becomes charged with 

 hydrogen in a state of solution : the body of water in con- 

 tact with the negative pole disengages hydrogen in a state of 

 elasticity ; this water, therefore, becomes charged with oxygen 

 in a state of solution. Thus we have, on one side, water 

 charged with oxygen, and on the other, water charged with 

 hydrogen, or, in other words, two liquids of unequal density. 

 From that moment the phenomenon of endosmosis presents 

 itself, and the water charged with oxygen being necessarily 

 of greater density than that charged with Hydrogen, has its 

 volume increased at the expense of the latter. Electricity 

 here is not the immediate, but the remote cause of the pheno- 

 menon : it is simply the cause of the difference in density of the 

 two portions of water. This difference is undoubtedly very 

 small, and, therefore, the phenomenon of endosmosis is 

 manifested in a very slight degree. 



A very celebrated mathematician (M. Poisson) has sought to 

 explain the phenomena of endosmosis on the principles of 

 capillarity. The following is a summary of the theory which 

 he has recently broached on the subject. The two hetero- 

 geneous liquids being introduced into the same capillary canal 

 by its two extremities, are at first both concave, but as soon as 

 they unite, the one remains concave, while the other becomes 

 convex, adapting itself to the concavity of its antagonist; then, 

 by a mechanism founded on calculations made by the learned 

 mathematician, the liquid which rises the highest, and 

 which has remained concave, passes through the membrane, 

 repelling the liquid opposed to it, and runs out : it thus 

 augments the mass of this opposed liquid, with which it is 

 mingled, U 2 



