I prepared a solution of hydrochlorate of soda, the density of which was 1.12, the den sity of the water being one. I took a part of this solution and to it added an equal volume of water, which gave it a density of 1.06. I bad thus two saline solutions, of which the excess of density, above the density of water, was 0.12 and 0.06. The excess was thus in the relation of two to one. From my former experiments, these two excesses ought to serve as measures of the endosmosis produced by well of these saline solutions, put successively into the same endosmometer plunged in pure water. In fact, having submitted both of the saline solutions to experiment, I obtained from the most dense solution an endosmosis exactly double of that which was produced by the least dense solution. I next inquired into the rela tion existing between the known density of these two saline solutions and water, and the power of capillary ascension possessed by the three fluids. I took a glass tube, whose capillary action raised water to the height of 12 lines at a temperature of + 10 degrees R. (50 Fahrenh.) I found that the same tube, at the same tem perature, raised to 61 lines the solution of hydrochlorate of soda, the density of which was 1.12, and that it raised to 91 lines the solution of the same salt, the density of which was 1.06.
1. The capillary ascension of the water being ....... 12 The capillary ascension of the most dense fluid being 61 The excess of the capillary ascension of water is 51 2. The capillary ascension of water being 12 The capillary ascension of the least dense saline solution being 91 The excess of the capillary ascension of water is 21 Thus the two excesses of the capillary ascen sion of water above the capillary ascension of each of these saline solutions are Si and 2Z, or and V. numbers which are in the relation of two to one, as are the two excesses 0.12 and 0.06 of the density of the two saline solutions above the density of water. I fere, then, are two saline solutions which, put separately in relation to pure water, produce endosmosis iu the relation of 2 to 1. Shall we refer this result to the circumstance that the excesses of density of each of these saline solutions over the density of water are in the ratio of 2 to 1, or to this, —that the excesses in the power of capillary ascent of each of these saline solutions over the power of capillary ascent of water are in the ratio of 2 to 1? In other words, is it the re spective density of the two fluids which regu lates or determines their endosmosis, or is it the respective powers of capillary ascension of the fluids severally ? The following experiment will solve this question. We have seen above that a solution of sulphate of soda and a solution of hydro chlorate of soda of equal densities being put in relation to pure water, produce endosmoses which are in the relation of two to one. Here the difference of density does not interfere with the regulation of the endosmosis; we must then see if it be regulated by the power of capillary ascension. I prepared a solution of sulphate
of soda and one of hydrochlorate of soda, having the same density 1.085, and tested their ca pillary ascension in the same tube in which we have seen pure water raised to a height of 12 lines at a temperature of + 10 degrees It. I found that in the same tube and at the same temperature the capillary ascension of the so lution of sulphate of soda was of 8 lines, and that of the solution of hydrochlorate of soda was of 10 lines. The excess of the capil lary ascension of water above that of the solu tion of sulphate of soda is consequently 4 ; the excess of the capillary ascension of water above the solution of hydrochlorate of soda is 2. These two excesses are in the relation of two to one, a relation which also measures the endosmosis produced with the concurrence of water by each of these two solutiOns of equal density. The result of this is that the capillary ascension, or power of capillary ascent, of fluids governs their endosmosis, and that their density only intervenes in this ease as the determining cause of their capillary ascension. But how does the capillary action operate here? This ap pears to be difficult to determine. The capillary action never carries fluids out of the canals in which it takes place; how then apply this action to the phenomenon of double permeation, which takes place in endosmosis and exosmosis ? This double permeation, which carries two he terogeneous fluids towards each other, seems as though it were the result of the reciprocal attraction of the two fluids, of their tendency to associate by admixture. In experiments of endosmosis made with a dense fluid and water, the tendency to mix is favoured by the respec tive positions of the two fluids ; the dense fluid is above and the water below. This dis position may possibly be one cause which fa vours the reciprocal mixture of the two fluids, whose specific gravity would tend to place them in an inverse situation to that given them in the experiment. This does not take place when experiments on endosmosis are made with alcohol and water; then the alcohol, spe cifically lighter than water, is situated above this latter fluid, and, notwithstanding this, the endosmosis is exceedingly energetic ; we must then acknowledge that the specific gravity of two fluids has not here the degree of influence that might be supposed to belong to it at first sight. We have consequently no means left to explain the course of the two fluids towards eaeh other athwart the capillary canals of the parti tion which separates them, but their reciprocal attraction or tendency to admixture. In ad mitting that such is the efficient cause of this double permeation we must also necessarily admit that this efficient cause is governed in its' operation by the capillary action of the par tition.