"Where, girt with clouds, the rifted mountain yawns, And chills with length of shade the gelid lawns, Climb the rude steeps, the granite-cliffs surround, Pierce with steel points, with wooden wedges wound; 525 Break into clays the soft volcanic slaggs, Or melt with acid airs the marble craggs; Crown the green summits with adventurous flocks, And charm with novel flowers the wondering rocks. --So when proud Rome the Afric Warrior braved, 530 And high on Alps his crimson banner waved; While rocks on rocks their beetling brows oppose With piny forests, and unfathomed snows; Onward he march'd, to Latium's velvet ground With fires and acids burst the obdurate bound, 535 Wide o'er her weeping vales destruction hurl'd, And shook the rising empire of the world. [_The granite-cliffs._ l. 523. On long exposure to air the granites or porphories of this country exhibit a ferrugenous crust, the iron being calcined by the air first becomes visible, and is then washed away from the external surface, which becomes white or grey, and thus in time seems to decompose. The marbles seem to decompose by loosing their carbonic acid, as the outside, which has been long exposed to the air, does not seem to effervesce so hastily with acids as the parts more recently broken. The immense quantity of carbonic acid, which exists in the many provinces of lime-stone, if it was extricated and decomposed would afford charcoal enough for fuel for ages, or for the production of new vegetable or animal bodies. The volcanic slaggs on Mount Vesuvius are said by M. Ferber to be changed into clay by means of the sulphur- acid, and even pots made of clay and burnt or vitrified are said by him to be again reducible to ductile clay by the volcanic steams. Ferber's Travels through Italy, p. 166.] [_Wooden wedges wound_. l. 524. It is usual in seperating large mill- stones from the siliceous sand-rocks in some parts of Derbyshire to bore horizontal holes under them in a circle, and fill these with pegs made of dry wood, which gradually swell by the moisture of the earth, and in a day or two lift up the mill-stone without breaking it.] [_With fires and acids_. l. 534. Hannibal was said to erode his way over the Alps by fire and vinegar. The latter is supposed to allude to the vinegar and water which was the beverage of his army. In respect to the former it is not improbable, but where wood was to be had in great abundance, that fires made round limestone precipices would calcine them to a considerable depth, the night-dews or mountain-mists would penetrate these calcined parts and pulverize them by the force of the steam which the generated heat would produce, the winds would disperse this lime-powder, and thus by repeated fires a precipice of lime-stone might be destroyed and a passage opened. It should be added, that according to Ferber's observations, these Alps consist of lime-stone. Letters from Italy.]