385 
“A. MESSAGE FROM THE STARS.” 
possess affinities which enable them to act on the material 
of the earthenware septum. Lime and alumina were always 
found in solution after osmose, and the corrosion of the septum 
appeared to be a necessary condition of the flow. Septa of 
other materials, such as pure carbonate of lime, gypsum, com- 
pressed charcoal, and tanned sole-leather, although not deficient 
in porosity, gave no osmose, apparently because they are not 
chemically acted on by the saline solutions.” 
Osmose appears to play an important part in the functions of 
life. In osmose there is also a remarkably direct substitution 
of one of the great forces of nature by its equivalent in another 
force, the conversion, namely, of chemical action into mechanical 
power. Viewed in this light, the osmotic injection of fluids 
may, perhaps, supply the deficient link which intervenes be- 
tween chemical decomposition and muscular movement. 
There is yet another set of phenomena which, although not 
generally associated with those which have been considered, 
appear, upon closer consideration, to be intimately related to 
them. These are the phenomena of catalysis , or contact 
action. A sheet of perfectly clean platinum being plunged 
into a mixture of oxygen and hydrogen, compels their union : 
the action of this metal in a spongy state is well known, and 
the action of ferments is familiar to all. Each of these are 
substances which have the power of establishing chemical rela- 
tions by the action of contact with considerable energy. 
We have seen that gases interpenetrate in a very remarkable 
manner, and that the diffusion of fluids into air, or into each 
other, exhibits a force sufficiently powerful to break up strong 
chemical affinities. We have observed the power of porous 
bodies in compelling the passage through them of gases and 
fluids ; capillarity has been briefly noticed, osmose action 
described, and contact action slightly indicated.* 
We have now to advance a step yet farther, and mention the 
surprising passage of gases through the homogeneous substance 
of a plate of fused platinum or of iron at a red heat, the dis- 
covery of H. St. Claire Deville and Troost. The porosity of 
graphite, of earthenware, of marble, and the action of those 
substances on gases and fluids, may be regarded as fairly under- 
stood. A new kind of porosity in metals is imagined, of a 
greater degree of minuteness than the porosity of graphite and 
earthenware ; this is an intermolecular porosity, due entirely to 
dilatation. At low temperatures neither platinum nor iron 
admits any passage of gas; but by the expansive agency of 
* In addition, the striking Memoir by Mr. Graham, 11 On the Absorption 
and Dialytic Separation of Gases by Colloid Septa ” (Phil. Trans, vol. 156, 
part ii. p. 399), should be studied. 
