Secondly, that even in the superficial lakes of molten or flowing matter, to which, after Mr. Hopkins, as we have seen, we must attri bute volcanoes,—universally distributed below the mere surface of the earth,—as shown by Mr. Darwin,—the result of the deposition on the bed of the ocean of new deposits, causing the rise of the isothermal surfaces, as demonstrated by Babbage and Herschel—in the more heated parts of those lakes water will exist, not as steam or as incandescent or ignited water, but as mixed but uncombined oxygen and hydrogen gases. At the same time the mere effect of heat will be modified by pressure, and the chemical action of the bodies present, so that we have here another great result perfectly in harmony with the thermotic theory on the one hand and the chemical theory on the other. But we are not to expect any evidence of the existence of free oxygen and hydrogen below to arrive at the surface, for as the upper parts of the molten flood will be of inferior temperature in them, or in their ignited solid roof, the gases will reunite into water, and eventually ascend to the surface, as steam, or mingled with the mineral elements of. lava, in some state intermediate between those of liquid and vaporous water, to be disengaged as steam in the volcano, and from the surface of currents of lava.
Thus, all the great powers and forces which govern the material elements of the globe mutually act and react upon each other. Pres
sure and condensation caused by gravity, combination resulting from chemical affinity or attraction, heat, producing alternately rarefaction or condensation, combination or separation, accordingly as it is related to the other forces ; the whole being so held in equilibrium between themselves and the antagonistic action of the sun upon the surface of the earth, that the magnitude, figure, order, and beauty of our planet are perpetually maintainexl.* (The reader may consult Daubeny Os Volcanoes; Poulett Scrope's Comiderations on Volcanoes, and Geotoqy and Volcanoes of Central France; Lyell, Principles and Manual of Geology, and Oa Xtea, in Phil. Trans., 1853; Darwin, Trans. Geol. Sec., Geol. of Volcanic Islands, Geol. of SoatA America ; 'De la Beebe, Geological Manual; Caldeleugh, in Pltil)sophital Tranmetioss; Humboldt, Cosmos, Trards, and Treatise ow Rocks ; Von Buch, Oa the Canary Islands ; Abich, 11., l'cber die Notar, d.c. der Vulkanischen Bildunges in Italics, and I'ucs Illuatra S. von Waltershausen, .4des de VEtria,and tidier die rulkanische Ceiteine, 4:c.; De Beaumont and Dufresnoy, On Auvergne ; Boudant, Ilungary ; D'Aubuisson's Geology; Bisehof, On Mineral Waters ; Rogers, On the Apallachian Chain; in Reports of Brit. Assoc., 1342 ; Prof. John Phillips, Treatise on Geology ; Mitchell, ' On Earthquakes,' Phil. Trans., 1760; Ansted'a Geolo.* Gossip.)