Penny Blood: Serial Sensation and Working-Class Entertainment — page 108: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

CH. VIII. } FLUID SUBSTRATUM. 9! could possibly find access to the hot interior; and these are, by open fissures, and by capillary absorption. If a fissure were to open at the bottom of the sea, so that water were to gain access to heated rocks, it seems incredible that the steam, if such were formed, should not be formed at once, and the water be forced back again through the same fissure by which it entered. Or if we suppose, as is probable, that the pressure of the water would prevent the formation of steam, still there would be a highly expansive fluid, which would rush upwards at the same place, rather than traverse a long underground journey to find exit at a neighbouring volcanic vent. The more plausible opinion is, that the water gains access by capillary absorption, and slowly accumulates in the supposed “volcanic foci,” until at last it bursts forth in an eruption. Capillary attraction can be made to do great things, as for instance to split blocks of granite, by driving in dry plugs of wood and wetting them. But it cannot cause a liquid to flow con- tinuously through a tube, however short ; for, if it could, 1t would give us perpetual motion. And after all it is a finite force and requires special conditions for its development. The chief of these is that surfaces of three media should meet two and two mn contact. Thus when water rises in a capillary tube of glass, we have the three media of glass and water and air. The tension of the surface separating water and air is greater than that of the surface separating water and glass’. In the present case, there is no third medium present, vapour of water, which might act as such, being prevented from forming by the pressure, so that 1t does not appear how the action can be set up. If there were a cavity filled with vapour, it is possible that the density of that vapour, and therefore its pressure, might be increased to a certain extent, by the evaporation of the water from the ex- tremity of the capillary tubes, and that was what occurred in the experiment of M. Daubrée*. But under the conditions 1 See Maxwell’s ‘‘ Heat,” 2nd ed. p. 286. 2 M. Daubrée (vide ‘“‘ Rapport sur les progras de la Géologie expérimentale,” Paris, 1867) deduced a theory of volcanos from the following experiment. He separated two chambers by a circular plate of rock two centimetres in thickness. The upper chamber communicated freely with the atmosphere, the plate of rock forming its lower face. The second chamber was empty, and communicated GONG oOo SS (CO)