ENDOSMOSIS. 



103 



in silence all the proofs that seem to establish 

 this theory upon a basis of sufficient solidity; 

 for I cannot but perceive that it is applicable 

 to the most general phenomena of endosmosis, 

 phenomena, too, which the acids, like all other 

 fluid bodies, exhibit, although they also present 

 endosmotic phenomena in addition of a diffe- 

 rent nature, and which belong to them exclu- 

 sively. 



Inequality of density being one cause of en- 

 dosmosis among fluids, it became a point with 

 me first to ascertain what differences in power 

 of capillary ascension resulted from determi- 

 nate differences of density among fluids ; and 

 next, to discover whether the difference in 

 power of capillary ascent of two fluids bore 

 any constant ratio to the difference of endos- 

 mosis as it is proclaimed by experiment. 



The height to which different fluids rise in 

 capillary tubes depends on a variety of causes, 

 in appearance very different, but which must 

 have some fundamental analogy. Of all fluids 

 water is that which rises highest; and sub- 

 stances held dissolved in it which increase its 

 density, lessen its power of capillary ascent, 

 which is also diminished by increase of tempe- 

 rature : hot water ascends a less way in a capil- 

 lary tube than cold water. Combustible fluids, 

 such as alcohol and ether, are like dense fluids 

 in regard to power of capillary ascent ; so that 

 combustibility acts in the same manner as den- 

 sity in this respect. The matter of which ca- 

 pillary tubes are formed is also endowed with 

 the power of modifying the capillary ascent of 

 fluids. Thus water, at the same temperature, 

 will not rise to the same height in a series of 

 equal capillary tubes made of different mate- 

 rials. These multiplied elements, which enter 

 into the determination of the capillary ascend- 

 ing power of different fluids, render it an ex- 

 tremely complicated phenomenon. To simplify 

 the study of this phenomenon in the greatest 

 possible degree, let us confine ourselves to the 

 use of two fluids, namely, water and a solution 

 of the hydrochlorate of soda. It is easy to try 

 the latter fluid of different densities, and to 

 compare the power of capillary ascent pos- 

 sessed by each of these with that of pure water 

 at like temperatures. The same glass tube will 

 answer for these comparative experiments. Be- 

 fore detailing these experiments, however, I 

 have one important remark to make, which is 

 this; that the layer of fluid which moistens, 

 internally, the canal of a tube is one of the 

 elements of the capillary ascension which this 

 tube effects. Thus, water will rise to a de- 

 terminate height, in a tube interiorly moistened 

 with water ; but if the interior of the tube be 

 moistened by a saline solution, or by any other 

 watery fluid, or by alcohol, pure water will not 

 again rise so high in this tube as when it was 

 moistened by water only. It will be in vain 

 to attempt to cleanse the tube by passing water 

 repeatedly through it; water will never detach 

 the stratum of saline or other liquid which ad- 

 heres to it, and which diminishes its power of 

 producing capillary ascension. To detach this 

 stratum of fluid you must pass a filiform body 

 repeatedly through the tube full of water ; it is 



only by the rubbing of this body that the stratum 

 can be detached. It must be evident after this 

 observation, that in making experiments on the 

 power of capillary ascension with various 

 fluids and with the same tube, it is necessary 

 to cleanse this tube with great care before each 

 experiment ; without this we should have de- 

 fective results. We must also take care not 

 to warm the tube by holding it between the 

 fingers, for if the temperature be increased it 

 will no longer exert so strong a capillary attrac- 

 tion. Let us now pass to the detail of these 

 experiments. 



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 

 had 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 

 each 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 6, lines the solution of 

 hydrochlorate of soda, the density of which 

 was 1.12, and that it raised to 9| 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 6 { 



The excess of the capillary ascension 

 of water is 5 $ 



2. The capillary ascension of water 



being 12 



The capillary ascension of the least 

 dense saline solution being 9| 



The excess of the capillary ascension 

 of water is 2 1 



Thus the two excesses of the capillary ascen- 

 sion of water above the capillary ascension of 

 each of these saline solutions are 55 and 2|, or 

 4 f and 2 f. 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. Here, then, are two 

 saline solutions which, put separately in relation 

 to pure water, produce endosmosis intherelation 

 of 2 to 1. Shall we refer this result to the 



