EXDOSMOSES PRODUCED ON THESE PRINCIPLES BY SOLUTION. 27 



77. The general result of these considerations proves, that if two different liquids, 

 which can dissolve one another, communicate through a tube which both can wet, 

 both of them will flow through that tube contemporaneously, the one passing in one, 

 and the other in the opposite direction ; and it is plain that all this is nothing more 

 than a simple case of common capillary attraction. 



78. What happens through one will, under similar circumstances, happen through 

 one hundred or any number of tubes. If, therefore, instead of a single tube C, a great 

 number of tubes were made to communicate between A and B, they would all act alike, 

 and through them the two liquids would simultaneously pass in opposite directions. 



79. It is also obvious that the shorter we make the tube C, or the supposed collec- 

 tion of tubes, the more readily will the flow take place, because the vessels A and B 

 are then made to communicate through a shorter obstacle. If, therefore, we take a 

 box, A ~B,Jig. 110, and divide it water-tight by any porous obstacle C, such as a piece 

 of paper, or bladder, or porous earthenware, &c., which substances may be regarded as 

 consisting of a congeries of very short tubes, their pores answering to such short tubes, 

 and in the compartment A place water, and in B alcohol, through the intervening bar- 

 rier interchange will take place ; and if there be no leakage, and one liquid passes more 

 rapidly iu its course than the other, not only will the interchange we have been de- 

 scribing take place, but there will be also an accumulation of liquid on one side of the 

 barrier C, and a diminution of it on the other. 



80. All this is irrespective of the shape or form of the vessels, which may be cubical, 

 or round, or of any other figure. The essential conditions for action are to have two 

 liquids, which have an affinity for one another, placed on opposite sides of a pervious 

 obstacle or porous barrier, which both of them can wet. Movement will then take 

 place in opposite directions ; and, if one liquid flows more rapidly than the other, there 

 will be an accumulation on that side of the barrier to which it goes, and a deficiency 

 on the other. 



81. M. Dt TROCHET took a bladder, and, filling it with alcohol, tied the mouth of it 

 tightly, so that none of the liquid could escape. He then placed it in a vessel of wa- 

 ter, and found that the alcohol came out of the bladder into the water, and the water 

 passed through the bladder into the alcohol, and, inasmuch as the water flowed more 

 rapidly than the alcohol, there was a constant accumulation within the bladder, dis- 

 tending it ; an accumulation taking place with sufficient force to burst it open, provi- 

 ded the experiment was continued long enough. 



82. To these phenomena M. DUTROCHET gave the name of Endosmose and Exos- 

 mose. the former in allusion to the current flowing inward, the latter to that flowing 

 outward. Physiologists were pleased with these sonorous designations, which ever 

 since have been used in the books. Some supposed that the force thus exerted by a 

 bladder was due to the remains of vitality still existing in it, arising from its organization. 

 It is, however, as we have seen, one of the ordinary cases of common capillary attrac- 

 tion, with which the vital force has no more connexion than its kindred principle 

 Phlogiston. 



83. The rise or depression of a liquid in a capillary tube is determined by its quali- 



