Physical Cause of Endosmosis. 287 



produced, but after some time this effect ceases, and the 

 liquid raised above its level has a tendency to fall by filtration 

 through the permeable partition. This occurs when the par- 

 tition is modified by the acid, the alkali, or the salt. Alcohol 

 produces the same effect, which results with extreme prompti- 

 tude from the action of sulphuric and hydro-sulphuric acids, 

 so much so, indeed, as to induce me to believe that these two 

 acids are opposed to the endosmosis. The organic liquids, not 

 having any chemical action on the membranes, or mineral 

 partitions which may be employed to close the endosmometers, 

 produce an endosmosis which would not be liable to any sus- 

 pension if they always remained the same. But these liquids 

 are decomposed and become acid or alkaline, and often be- 

 come charged with sulphuretted hydrogen. From that mo- 

 ment, their endosmosing action becomes liable to be destroyed. 

 Thus a membrane acidified, salified, or alkalised, as much as 

 it can be by the acid, saline, or alkaline liquid with which it is 

 in contact, will no longer produce any endosmosis with the 

 same liquid. In order to obtain an endosmosis, which will not 

 cease spontaneously, a permeable partition must be placed in 

 contact, on one side with pure water, and on the other with 

 a liquid which has no chemical action on it. Thus if we put 

 a solution of muriate of soda into an endosmometer closed 

 with- a plate of clay, an endosmosis will be produced which 

 will not cease. But if the partition of the endosmometer 

 were membranous, the endosmosis would cease as soon as the 

 partition became salified. Sulphuretted hydrogen puts an end 

 to the endosmosis produced with a plate of clay, as well as 

 with a membrane ; because, in both cases, it combines with 

 the elements of the permeable partition. The extreme rapidity 

 of this combination is the cause of the rapid manner in which 

 that substance puts an end to the endosmosis. The same 

 effect is produced by sulphuric acid ; but I repeat, that it will 

 also be produced by all liquid substances, which are susceptible 

 of combination with the elements of the permeable partitions 

 of the endosmometer ; the only difference in that respect is in 

 the rapidity of the combination. It is not easy to determine 

 with exactness the physical causes of these latter phenomena; 

 but it is evident that they depend upon the capillary action 

 which is modified in the permeable partitions by the chemical 



