increasing " The defects of the present government of Egypt, and the discovery of the passage from Europe to India iound the Cape of Good Ilope, are therefore not the only causes of the present state of decline of this coun try. If the sands of the desert had not invaded the bordering lands on the west, if the work of the sea po lypi in the Red Sea had not rendered dangerous the ac cess to its coasts and to its ports, and even filled up some of the latter, the population of Egypt and the ad jacent countries, together with their product, would alone have sufficed to maintain them in a state of pros perity and abundance. But now, though the passage to India by the Cape of Good Hope should cease to exist, though the political advantages which Egypt enjoyed during the brilliant period of Thebes and Memphis should be re-established, she could never again attain the same degree of splendour.
" Thus the reefs of coral which had been raised in the Red Sea on the east of Egypt, and the sands of the desert which invade it on the west, concur in attesting this t uth : That our continents are not of a more re mote antiquity than has been assigned to them by the sacred historian in the book of Genesis, from the great era of the Deluge," Sea-salt affords us examples of the chemical forming effect of water, as is exemplified in the lakes of the Tauride, in Southern Africa, and many other places. We there observe beds of salt formed by precipitation from the waters of the lakes ; and sometimes these beds alternate with others of clay and loam, and vary much in their degree of inclination. Bog iron-ore, which is forming daily, is another example of the same kind of formation. Morass-ore sometimes alternates in beds with peat ; and swamp-oar sometimes occurs in thin beds, covering the more compact kinds of peat. Peat itself may be ranked as one of the substances formed by chemical agency.
The vast accumulations of calc-sinter found in lime stone caves, as in those of Derbyshire, the Hartz, the Fichtelgebirge, Antiparos, Gibraltar, Stc. belong also to the chemical formations. Calc-sinter is found usually in inclosed spaces, whereas calc-tuff is formed in open spaces. This substance is deposited sometimes in caves, and frequently in fissures, forming veins, which are in this manner filled with very compact calc-sinter, and sometimes even with crystallized calc-spar. Calc-tuff
is formed by calcareous brooks emptying themselves into hollows, and thus affording an opportunity for the deposition of their calcareous contents. Near Canstadt in Wurtemberg, streams of this kind incrust every thing in their vicinity with calc-tuff, which approaches more or less to calc-sinter. If such streams flow into situations where the water has repose and time to de visite its calcareous contents, calcareous beds or strata are formed, which are more or less porous. This po rosity is increased on the land, by the tuff mixing with reeds and grass. In beds of this substance skeletons of extinct quadrupeds arc met with.
Des:hying and forming effects of Volcanoes The operation of volcanoes is still more limited and local than that of water. Although we are entirely ig norant of the means employed by nature in producing volcanic fire, we can judge by its effects of the changes it is capable of producing upon the surface of the earth. When a volcano announces itself after some shocks of an earthquake, it forms for itself an opening. Stones and ashes arc thrown to a great distance, and lava is vomited forth. The more fluid part of the lava runs in long streams, while the less fluid portion stops at the edge of the opening, raises it all round, and forms a line terminated by a crater. Thus volcanoes accumu late substances on the surface that were formerly bu ried deep in the bowels of the earth, after having changed or modified their nature or appearances, and raise them into mountains. By these means, they have formerly covered some parts of the continents, and have suddenly produced mountains in the middle of the sea. But these mountains and islands have always been corn posed of lava, and the whole of their materials have undergone the action of fire. Volcanoes have never raised up or overturned the strata, through which their apertures pass, and have in no degree contributed to the elevation the great mountains which are not vol canic.*