VOLCANO. 
S 62 
powdered sulphur, and the whole moistened 
with water into a paste, will swell, become 
hot, and if the quantity is considerable, will 
throw out a blue flaraev It is a mixture of 
tiiis kind which is used for making an artifi- 
cial earthquake ; for such a quantity of in- 
flammable gas is produced during the fer- 
mentation, that if the mass is buried in the 
earth, the gas will force a passage for its es- 
cape, and exhibit, on a small scale, the phe- 
nomena of an earthquake. M.Lemery seems 
to have been the first person who illustrated, 
in this manner, the origin of volanic fires and 
earthquakes. He mixed twenty-five pounds 
of iron-tilings with an equal weight of sulphur, 
and having made them into a paste, with the 
addition of water, he put them into a pot, 
covered them with a cloth, and buried them 
a foot under ground. In about eight or nine , 
hours lime the earth swelled, became warm, 
and cracked, and hot sulphureous vapours 
were perceived. Now large beds of martial 
pyrites, sulphu ret of iron, are known to exist 
in different parts of the earth ; the only diffi- 
culty which attends this explanation of the 
origin of volcanoes, as well as of earthquakes, 
is, that the presence of air is in general ne- 
cessary for the production of actual flame. 
It is well known, however, that sulphuret of 
iron, when moistened, acquires heat ; and 
if we suppose it to have been in contact 
with black wad and petroleum, we may sup- 
pose the flame to arise, as we see it produced 
by art, from the desiccation of the former 
substance, and its mixture with mineral oil. 
Many minerals, when heated, afford oxygen 
gas, a very small quantity of which is suffi- 
cient to produce flame ; this flame, once 
produced, may be supported from other 
©res, and the combustion be maintained by 
the presence of bituminous schistus, bitumen, 
and coal. Marl, schistus, horn-stone, schorl, 
with a further addition of iron, are the true 
sources of iava. It seems, however, after all, 
difficult to conceive that such extensive and 
intense fires should be maintained without the 
•access of considerable quantities of air ; that 
fluid may therefore be possibly supplied by 
a communication with some extensive ca- 
verns, which may themselves receive it by 
openings at the distance of many miles from 
tiie crater of the volcano. It does not seem 
! improbable that the volcanoes, which now 
burn, may have a communication with the 
cavities and craters of extinguished volca- 
noes, and thence derive a supply of air suffi- 
f cient to account for the inflammation of large 
beds of pyrites and bituminous matters. M. 
Buffon supposes, that the seat of volcanic 
fires is situated but a very little way below 
the bed of the mountains ; but it appears 
more probable, that it is in general many 
miles below the surface of the earth, for the 
quantity of matter discharged from Etna 
alone is supposed, on a moderate calculation, 
to exceed twenty times the original bulk of 
the mountain, and therefore could not have 
been derived from its contents alone, but 
must come from the deeper recesses of the 
earth. 
M. Condamine asserts, that all the moun- 
tains in the neighbourhood of Naples exhibit 
r undoubted marks of a volcanic origin. He 
says, he could trace the lava, and other pro- 
! cluctions of subterraneous fire, from Naples 
to the very gates of Rome, pervading the 
whole soil, sometimes pure and sometimes 
differently combined. “ Wherever I see,’’ 
says he, “ on an elevated plain, a circular 
bason, surrounded with calcined rocks, I am 
not deceived by the verdure of the adjacent 
fields ; I can discover, beneath the snow it- 
self, the traces of an extinguished fire. If 
there is a breach in the circle, I usually find 
out, by foliowing the declivity of the ground, 
the traces of a rivulet, or tire bed of a torrent, 
which seems as if it was hollowed in the rock, 
and this rock appears frequently to be pure 
lava. It the circumference of the- basen has 
no breach, the rain and spring waters, which 
are collected there, generally form a lake in 
the very mouth of the volcano.” The Ap- 
penines, as well as the Cordilleras of Peru and 
Chili, he supposes to have been a chain of 
volcanoes. The chain, in both instances, is 
interrupted,-and many of the fires either ex- 
tinguished or smothered, but many remain 
still actually burning. This intelligent au- 
thor is, however, far from attributing to all 
mountains the same origin ; and adds, that 
in that part of the Alps, which he travelled 
over, he could observe no such appearances. 
The traces of volcanoes have been observ- 
ed in Ireland by Mr. Whitehurst. Though 
no visible crater is remaining between Port 
Kush Strand and Ballycastle eastward, yet, 
he observes, that whole space, about twenty 
English miles, is one continued mass of lava. 
The cliffs, he says, are truly stupendous, and 
bear every possible mark of having been ori- 
ginally liquid fire. The elevation of that, at 
the foot of which the Giant's Causeway is 
situated, he presumes cannot be less than five 
or six hundred feet perpendicular above the 
level of the Atlantic ocean, and yet com- 
posed entirely of lava ; the same appearances 
extend towards the south upwards of twenty 
miles. 
The most remarkable volcanoes in Europe 
are Etna and Vesuvius; and as these are not 
too far distant, we have the most accurate 
descriptions of them from travellers of the 
first talents and reputation. 
Etna, which is the most striking object in 
Sicily, and indeed one of the most magnifi- 
cent productions of nature, rises from an im- 
mense base, and mounts equally on all sides 
to its summit. The ascent on each side is 
computed at about thirty miles, and the cir- 
cumference of its base, at one hundred and 
thirty-three ; but as it has never been mea- 
sured with any great degree of accuracy, its 
dimensions are but imperfectly known. 
The whole mountain is divided into three 
distinct regions, called La Region Culta, or 
Piedmontese, the fertile region ; La Regiona 
Sylvosa , or Nemorosa, the woody region ; 
and La Regiona Deserta, or Scoperta, the 
barren region. These differ as materially 
both in climate and production as the three 
zones of the earth, and perhaps with equal 
propriety might have been styled the torrid, 
the temperate, and the frigid zone. 
The first region of Etna surrounds the 
base of the mountain, and constitutes the 
most fertile country in the world on all 
sides of it, to the extent of fourteen or 
fifteen miles, where the woody region begins. 
It is composed almost entirely of lava, which, 
in time, becomes the most fertile of ail soils; 
but the roads, which are entirely over old 
lavas, now converted into orchard;, vine- 
yards, and corn-fields, are execrable. The 
lavas, which form this region, arise from a 
number of beautiful little mountains, every 
where scattered over the immense declivities 
ot Etna. These are all either of a conical or 
hemispherical figure, and are in general co- 
vered with beautiful trees, and the most 
luxurious verdure. The formation of them 
is owing to the internal fires of Etna, which, 
raging lor a vent, at so vast distance from the 
great crater, that it cannot possibly be car- 
ried to the height of twelve or thirteen thou- 
sand feet, which is probably the height of the 
summit of Etna, must necessarily be dis- 
charged at some other orifice. After shaking 
the mountain, and its neighbourhood, for 
some time, at length the fire bursts open its 
side, and this is called an eruption. At first 
it emits only a thick smoke and showers of 
ashes. These are followed by red-hot stones, 
and rocks of a great size, which are thrown 
to an . immense height in the air. These 
stones, together with the quantities of ashes 
discharged at the same time, form those 
mountains, which cover all the declivities of 
Etna. 1 he size of them is in p opoilion to 
the duration of the eruption. YVhen it con- 
tinues- a considerable time, it sometimes 
forms an elevation of one thousand feet in 
perpendicular height, which at its base is 
seven or eight miles in circumference. 
After the formation of the new mountain, 
the lava commonly bursts out from its lower 
side, and, sweeping every thing before it, is - 
general!) terminated by-the sea. Sometimes 
it issues from the side of the mountain, with- 
out these attending circumstances, which is 
commonly the case with the eruptions of Ve- 
suvius; in which the elevation being so much 
smaller, the melted matter is carried up into 
the crater, where it is dislodged without 
forming any new mountain, but only adding 
to the height of the old one; till at length the 
lava, rising near the summit, bursts the side 
of the crater. Rut Etna being upon a much 
larger -scale, one crater is not sufficient to 
give vent to such immense oceans of liquid . 
iire..- 
Many striking remains of the great erup* 
tion in 1669 are still to be seen, and will long 
continue as memorials of that dreadful event 
which overwhelmed Catania, and all the ad- 
jacent country. Tremendous earthquakes 
shook the island, and subterraneous bellow- 
ings were heard in the mountain. During 
some weeks, the sun ceased to appear, ancl 
the day seemed changed into night. Borelli, 
who was a witness to these terrible pheno- 
mena, says, that at length a rent, twelve 
miles in length, w as opened in the mountain, 
in some places of which, when they threw 
down stones, they could not hear them reach 
the bottom. Burning rocks, sixty palms in 
length, were thrown to the distance of a mile, 
and lesser stones were carried three miles. 
After the most violent struggles, and a shak- 
ing of the whole island, an immense torrent 
of lava gushed from the rent, and sprung up 
into the air to the height of sixty palms, 
whence it poured down the mountain, and 
overwhelmed every object in its way in one 
promiscuous ruin. 
This destructive torrent, which burst from 
the side of Etna, at a place called Rich.i, 
rushed impetuously against the beautiful 
mountain of Montpelieri, and pierced into 
the ground to a considerable depth ; there ■ 
dividing and surrounding the mountain,- it', 
