Penny Blood: Serial Sensation and Working-Class Entertainment — page 207: what you’re looking at

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

190 COMPRESSION AND VOLCANIC ACTION |cu. xv. to the volume of the rocky matter. We conceive this associa- tion between the two at an exalted temperature and under great pressure, which has been called igneo-aqueous solution, to be not an ordinary solution of the rock in the water, but rather of the water in the rock, for we cannot suppose that the small relative quantity of water which is present can hold the rock in solution as salt is held in solution in water. And the water perhaps acts in the manner of a flux rendering the rock fluid at a lower temperature than that at which it would be fusible without it. Prof. Judd compares the process with the power, known to be possessed by “various solids and liquids, of absorb- ing many times their volume of certain gases’.” We know from the behaviour of lava in a volcanic vent that when the pressure is diminished the water separates from the rocky matter into vesicles which are at first of microscopic minuteness, but eventually these joi one another, expand, and ascend to the surface, producing ebullition. Since then there is apparent this tendency for the water to separate when the pressure is diminished, and since when it does separate it rises through the lava, it seems a necessary conclusion that under the pressure of the crust the density of the magma is uniform, for if it were not so, the water would rise to the surface of it and form a layer upon it. That there should be a layer of water-substance interca- lated between the crust and the substratum is on many accounts in the highest degree improbable. We must therefore arrive at the conclusion, startling though it may appear, that the water- substance in the magma is reduced by solution under pressure to the same density as the rocky matter with which it is combined. } The fact that the water-substance separates from the lava when the pressure is diminished, leads us to conclude that the quantity of 1t which the magma is able to hold in solution at a given temperature must be dependent on the pressure. If then 1 *Voleanoes,” p. 845. See also a notice by Mr Hannay “On the absorp- tion of gases by solids,” Proc. Royal Soc., Vol. xxxu, p. 407. 1881. His experiments appear to be in accordance with the assumptions here made. COMIC OOOKS.EO rn - —eeeeee, = =8-