410 GENERAL OBSERVATIONS 
between the interior of the globe, which is ina state 
of fusion, and the atmosphere which envelopes the 
hardened and oxidated crust of our planet. Masses 
of lava issue like intermittent springs ; and the su- 
perposition of their layers which takes place un- 
der our eyes bears a resemblance to that of the an- 
cient crystalline rocks. On the crest of the cordil- 
leras of the New World, as well as in the south of 
Europe and the western parts of Asia, an intimate 
connexion is manifested between the chemical action 
of volcanoes, properly so called, or those which pro- 
duce rocks,—their form and position permitting the 
escape of earthy substances in a state of fusion,— 
and the mud-voleanoes of South America, Italy, and 
the Caspian Sea, which at one period eject frag- 
ments of rocks, flames, and acid vapours, and at 
another vomit muddy clay, naphtha, and irrespir- 
able gases. There is even an obvious relation be- 
tween the proper volcano and the formation of beds 
of gypsum and anhydrous rock-salt, containing pe- 
troleum, condensed hydrogen, sulphuret of iron, and, 
occasionally, large masses of galena; the origin of 
hot-springs ; the arrangement of metallic deposites ; 
earthquakes, which are ever and anon accompanied 
by chemical phenomena ; and the sometimes sudden, 
and the sometimes very slow elevations of certain 
parts of the earth’s surface. 
This intimate connexion between these diversi- 
fied appearances has of late years served to eluci- 
date many problems in geology and physics which 
had previously been considered inexplicable. The 
analogies of observed facts, and the strict investi- 
gation of phenomena of recent occurrence, gradually 
lead us to more probable conjectures as to the events 
of those remote periods which preceded historical 
