HTDROGENIUM. 
235 
it, through the interstitial spaces of the fluid, up to the point of 
saturation ; when the solution-power ceases, and that it is a case 
of a similar nature to the solution of sulphuretted hydrogen in 
charcoal. Mr. Graham has, long since, beautifully shown the 
power of this surface force in water. Anyone can repeat a 
simple experiment, and greatly interested will he be in watching 
the result. If to a solution of sulphate of copper some liquid 
ammonia is added, we produce that beautiful purple solution 
which marks the shop of a druggist. Fill a small bottle with 
this solution, and, placing a little bit of window-glass over the 
mouth of the bottle, lower it, by means of a string, into a con- 
fectioner’s jar full of water. When it rests steadily at the 
bottom of the jar, carefully, with a rod, strike off the glass cover 
from the bottle. The water and the ammonia-sulphate of copper 
are in contact, but they do not mix. Gradually it will be 
observed that the purple solution loses colour, becoming a pale 
blue. The chemical combination has been overthrown — the 
ammonia has left the sulphate of copper and diffused itself 
through the water. In a similar manner, yet more powerful 
chemical combinations may be broken up. 
We are acquainted with other phenomena, in which modified 
conditions of the force which we have been considering are 
strikingly shown. Exosmose and endosmose — or, as Mr. 
Graham terms it. Osmose Force — exhibits phenomena of a pecu- 
liar character, yet a cautious examination appears to lead to the 
conclusion that there is little essential difference between it 
and the forms of force which have been described. A porous 
tile, a wall of clay, a piece of animal membrane, dividing 
two fluids, differing but slightly in their character — say, for 
example, sugar and water — shall be on one side of the partition, 
and water only on the other. Porosity immediatel}^ begins its 
work : the solid substance in solution (this mode of expression 
can scarcely be avoided, but the substance in solution does not 
exist in the solid state) passes through in one direction while 
a little of the purer fluid passes through in the other direction. 
Flowing in and flowing out goes on until all the sugar, or other 
substance, leaves its own cell and settles itself in the other. 
By this process numerous chemical decompositions can be 
effected, as in the cases already cited. In each and all of these 
phenomena, it is tolerably certain that we are dealing with an 
obscure, but a most energetic force, possessing more resemblance 
to gravitation than to any other known power, but distinguished 
from it by broad lines of difference. In gravitation we discover 
a power acting, irresistibly, amongst the particles of matter, 
drawing all to a mathematical centre, while, at the same time, 
we detect an influence — is it diffusive ? — which binds mass to 
mass in space and regulates the motions of worlds. In the sur- 
