Penny Blood: Serial Sensation and Working-Class Entertainment — page 109: what you’re looking at

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

92 FLUID SUBSTRATUM. [cH. VuII. present the pressure is too great for the formation of vapour, and the temperature too high for capillary attraction to be developed’. : Still further the existence of capillary communication of water from the surface may be doubted. For if there were sup- posed a capillary tube extending from the bottom of the ocean, the pressure at the lower end of this tube would be that of the water contained in it plus that, if any, arising from capillarity, while the pressure of the crust around its mouth would be that due to the weight of the crust. This latter would be the greater of the two, consequently the liquid upon which the crust rested, having a tension equal to the weight of the crust, would force back the water in the tube, and if it were not too viscous would itself occupy the tube. Thus it appears that the waters of the ocean cannot supply the steam emitted from volcanic vents. The conclusion seems inevitable that water substance holding sea salts in solution, is an original constituent of the magma from which these vaporous emanations are de- rived. What is this magma ? with a manometer. The entire apparatus having been raised to 160°, water was poured into the upper chamber; and soon afterwards the manometer was found to indicate two atmospheres of pressure. When a portion of the vapour accu- mulated in the lower chamber had been allowed to escape, the pressure soon recovered its former value. There was then a true feeding across the partition of rock, the cause of which was the desiccation of the lower face of the partition by vaporization of the water in its interstices, and the subsequent replacement of that water by capillary attraction. (Capillary attraction acted the part of the force-pump which feeds a high-pressure boiler.) M. Daubrée conceives that if the layer of rock were of great thickness, and a very high temperature maintained in the cavity, a correspondingly high steam- pressure would result, which would be sufficient to raise lava in the vent of a volcano, and to produce earthquakes; while the force so obtained might after expenditure be again and again renewed. This theory requires the occurrence of cavities at great depths (‘‘ supposons une cavité séparée des eaux de la surface’’) communicating with the volcanic vents. But the only argument in favour of cavities existing seems to be that the requisite mechanical force is supposed obtainable by means of them; but it seems & priori impossible that there should be such cavities, 1 Jn all liquids on which experiments have been made the superficial tension diminishes as the temperature rises, being greatest at the freezing point of the substance, and vanishing altogether at the critical point where the liquid and gaseous states become continuous.”. Maxwell’s ‘‘Heat,”’ 2nd ed., p. 290, COMiCOOokxS.conn