These are all esteemed to have been volcanic productions that have undergone different degrees of heat; it is well known that in Papin's digester water may be made red hot by confinement, and will then dissolve many bodies which otherwise are little or not at all acted upon by it. From hence it may be conceived, that under immense pressure of superincumbent materials, and by great heat, these masses of lava may have undergone a kind of aqueous solution, without any tendency to vitrification, and might thence have a power of crystallization, whence all the varieties above mentioned from the different proportion of the materials, or the different degrees of heat they may have undergone in this aqueous solution. And that the uniformity of the mixture of the original earths, as of lime, argil, silex, magnesia, and barytes, which they contain, was owing to their boiling together a longer or shorter time before their elevation into mountains. See note XIX. art. 8. The seat of volcanos seems to be principally, if not entirely, in these strata of granite; as many of them are situated on granite mountains, and throw up from time to time sheets of lava which run down over the proceeding strata from the same origin; and in this they seem to differ from the heat which has separated the clay, coal, and sand in morasses, which would appear to have risen from a kind of fermentation, and thus to have pervaded the whole mass without any expuition of lava. [Illustration: _Section of the Earth. A sketch of a supposed Section of the Earth in respect to the disposition of the Strata over each other without regard to their proportions or number. London Published Dec'r 1st 1791 by J. Johnson St Paul's Church Yard._] All the lavas from Vesuvius contain one fourth part of iron, (Kirwan's Min.) and all the five primitive earths, viz. calcareous, argillaceous, siliceous, barytic, and magnesian earths, which are also evidently produced now daily from the recrements of animal and vegetable bodies. What is to be thence concluded? Has the granite stratum in very antient times been produced like the present calcareous and siliceous masses, according to the ingenious theory of Dr. Hutton, who says new continents are now forming at the bottom of the sea to rise in their turn, and that thus the terraqueous globe has been, and will be, eternal? Or shall we suppose that this internal heated mass of granite, which forms the nucleus of the earth, was a part of the body of the sun before it was separated by an explosion? Or was the sun originally a planet, inhabited like ours, and a satellite to some other greater sun, which has long been extinguished by diffusion of its light, and around which the present sun continues to revolve, according to a conjecture of the celebrated Mr. Herschell, and which conveys to the mind a most sublime idea of the progressive and increasing excellence of the works of the Creator of all things?