(JO IS THEREFORE NOT DUE TO VITALITY. 



roneous results, through inattention to the conditions of hydrostatic equilibrium. If 

 two fluids be placed in the opposite arms of an inverted siphon, they will have a com- 

 mon level only when their specific gravity coincides ; and, under all other circumstances, 

 the height of their columns will be inversely proportional to their specific gravity re- 

 spectively. If, then, we take a tube, and make its extremity end in a fine capillary termi- 

 nation, or close it with a plug of wood or of stucco, and fill it with some dense solution, 

 such as chloride of sodium, sulphate of potash, or sulphate of copper, and then immerse 

 it to the same level in pure water, the level of the fluid in the tube will descend in 

 obedience to the laws of hydrostatics, and when a position of equilibrium is gained, the 

 heights of the fluid inside and outside of the tube will be inversely proportional to their 

 specific gravities. In all this, endosmosis or capillary attraction has no concern. 



194. In structures the pores of which are of such a diameter that these adjustments of 

 level can freely take place, the mechanical phenomena of endosmose are not visible ; 

 there is no fact that can indicate what is the true action of the porous body. All 

 bodies which exhibit these phenomena have their pores of such a size that, while they 

 offer resistance to change of level by mere leakage, they allow indefinitely small colums of 

 the fluid they are exposed to to interchange through them. 



195. We are not to expect that any of the phenomena of molecular infiltration will be 

 exhibited when the apertures through which transudation occurs are of considerable size. 

 If a piece of coarse linen is made use of as the separator of two fluids, those fluids will 

 commingle without any disturbance of hydrostatic level. Whenever this latter equilibrium 

 can be effected, it takes place, and entirely masks the molecular action of the mass. For 

 this reason, most minerals fail to show the change of level when water passes into alcohol. 

 They do not possess the exact kind of porosity required, either having their interstices 

 of so large a size that derangements of level can be quickly compensated, or, on the 

 other hand, being totally impervious to the liquids. I found that the common white 

 earthenware, when its glaze was removed, allowed water to percolate through it to gum- 

 water, but no disturbance of level was observed, simply because the freedom of commu- 

 nication between the two liquids was so great, that if one of them had a higher level than 

 the other purposely given to it, it soon returned to its original position of equilibrium. 

 A fragment of thick Hessian crucible gave the same result, as also several varieties of 

 slate, iron slate and mica slate, some of which were calcined and others in their ordi- 

 nary condition ; also a fragment of common writing slate, which had undergone semi- 

 vitrification in the forge. This freedom of communication was noticed in some speci- 

 mens of soapstone, both burned and unburned ; and while, in plaster of Paris, the ex- 

 periment failed because the apertures were too large, in the transparent micas it failed 

 for want of communication. To show, therefore, the original experiment of Dutrochet, 

 the interstices of the barrier must be of such a diameter that all mechanical compensa- 

 tions for change of level are hindered, and free molecular infiltration can take place. 



196. If a tube half an inch in diameter and three or four inches long be sealed at one 

 end, and while the glass is yet warm be dipped into water, a number of small cracks 

 will be made in its bottom. This forms a very useful instrument for studying the 

 properties here under discussion. If it be filled to a certain mark with alcohol, and 



