Page:The American Cyclopædia (1879) Volume VI.djvu/777

 ETNA 761 Dr. Frankland obtained it by the action of zinc upon iodide of ethyle at a high temperature. Its formula is C 2 H 5 when in combination ; but when free it is regarded as the double of this, C 4 Hio. It is a colorless, inflammable gas, having a slight ethereal odor (of which it would probably be devoid if absolutely pure) and a specific gravity of 2*00394. At a pres- sure of 2-25 atmospheres, and a temperature of 37 F., it becomes a colorless, transparent, mobile liquid. It is nearly insoluble in water, but soluble in absolute alcohol. It enters into the composition of a great number of com- pounds, comporting itself in the manner of a in on atomic basylous radical, analogous to hy- drogen and potassium, the chloride, bromide, nitrate, &c., containing one atom of C 2 H B ; the oxide, sulphide, neutral sulphate, and other neutral ethyle salts of dibasic acids containing two atoms of C 2 H 6 ; and those of tribasic acids, three atoms of C 2 H 6. It also unites with other alcohol radicals, producing com- pound alcohol radicals having a composition analogous to ethyle itself. ETNA (Lat. jfitna, probably from Gr. aZ0wv, to burn), a volcano of Sicily, called by the inhabitants of the island Mongibello, from a combination of the Italian monte with the Sara- cenic jebel, also meaning mountain. It rises from the E. coast of the island, midway be- tween its N. and S. extremities. The port of Catania is on the prolongation of its S. foot, and, as its history shows, is by no means beyond the reach of its devastating lava currents. North of the mountain is the Val di Dernone' watered by the river Alcantara ; and 30 m. s! of it is the N. margin of the Val di Noto, in which the waters of the Giaretta find their way toward the coast amid the ancient scoriae of the great volcano. The country between these rivers is occupied by the mountain with its various ridges, volcanic cones, and deep depressions, which cover altogether an area of about 87 m. in circumference ; yet the lava has spread far beyond these limits. In the midst is the apex of the great conical mass, the high- est summit, as ascertained by Sir J. Herschel in 1824, being 10,872^ ft., or 10,835 according to a measurement adopted by Petermann in his latest maps. The latitude of the point is 37 43' 31" N., the longitude 15 E. The cone, at the summit of which is the great crater, is in the midst of a comparatively level region, 9 m. in circumference, the highest point being 1,100 ft. below the principal apex. Around the mountain, at its base, is a fertile Mount Etna from Catania. and delightful region known as the regione culta. Near Catania this is 11 m. broad, till one reaches in ascending the regione silvosa, or woody district ; but on the N. side the wood skirts the mountain to within half a mile of its foot. This lowest belt is the region of cultiva- tion ; towns and villages are clustered upon it ; and in the rich soil of the decomposed lava and tufa are flourishing plantations of olives, vines, grain, fruits, and aromatic herbs. Though in the frequent eruptions some of these are often swept away, or buried beneath the flow of lava, the attractions of the delicious climate, and of a soil so productive, overcome the fears of a people familiar with the danger, and render them comparatively indifferent to the annoy- ances of the sharp volcanic dust. The woody region encircles the mountain in a belt 6 or 7 m. in width ; but the extensive forests are much broken in upon by the ravages of the lava. Here are fine groves of chestnut and cork trees, and in the higher portions pines of great magni-