DECOMPOSITIONS BY TERNARY ARRANGEMENTS. 33 



thin, imperceptible film, is instantaneously permeated by almost every substance, under- 

 goes the like action in course of time, even in deep masses. Gases are absorbed by it, 

 and thrown off" by it in its purest state ; how much more complicated, then, must its 

 action be in that impure condition in which it is commonly used. Connected with this 

 point there is another : if a series of bells stand on a pneumatic trough, each will affect 

 all the others, communicating a part of its contents, and receiving from them in return. 

 A jar, containing binoxide of nitrogen, standing by the side of one containing com- 

 mon air, seriously affects it I have noticed two common tumblers, filled with these 

 gases, and so placed, communicate with each other so freely, that in 17 hours the tum- 

 bler originally filled with atmospheric air contained only 9| per cent of oxygen. The 

 habit of collecting gases at the same trough, that is destined to preserve others, is very 

 exceptionable ; we place the disturbing agency in circumstances the most favourable 

 for its action. All operations of washing are liable to the same strictures. 



101. We have assumed it as a law of nature, that any substance, when placed in con- 

 tact with another, has a tendency to diffuse into it 



102. It is to be remarked in reference to this, that no hypothetical cause is assumed ; 

 it is merely taken as one of those ultimate facts which the progress of knowledge has 

 not explained. We do not consider whether it involves the position that two bodies 

 can exist in one place at one time, nor do we deny the impenetrability of matter. 

 But it is required of us by a crowd of facts to admit this law, as the only legitimate 

 position on which they can be explained. We know nothing of the size, or figure, or 

 condition of the ultimate atoms of bodies; there are, indeed, some circumstances which 

 would lead us to suppose that, even in the densest structures, each particle is at an 

 immense distance from those that are next around it, in comparison with its own 

 diameter. In those interstices which must necessarily exist, these phenomena of ab- 

 sorption may take place in accordance with laws which obtain among the molecules 

 of bodies. In the same way that a comet comes down from the regions of space and 

 traverses a planetary system, receiving impressions greater or less from each star that 

 it passes, and emerges back again untouched and unimpaired; so a gaseous particle 

 may pass through the system of atoms that constitute a solid mass, and moving therein 

 unimpeded and without contact with any of them, may emerge without change of 

 physical condition, or only a mark that its motion has been subject to those laws which 

 obtain in the system through which it has gone. 



103. All these observations go to establish the point, that pores of a sensible size 

 have nothing to do with endosmosis that it is a phenomenon depending simply on 

 absorption. No one would aver that water possessed any apertures, or vessels, or tubu- 

 lar arrangement. 



104. The experiment of (80) does not alone prove that endosmosis takes place 

 through liquids and tissues the pores of which have no sensible size; it has a much more 

 interesting application. Physiologists know that the primitive form of all organic bod- 

 ies is an imperforate vesicle or globule, having the power of absorbing those substances 

 which are around it, and decomposing them. The ultimate vesicle yields to analysis 

 carbon, the elements of water, and a few salts. It is a centre of vital activity, a 



E 



