> VOL 
naries whose figure is much like that of a 
flask of flanch, only that it doth not bend 
so much. 
V(JLaNT, in heraldry, is when a bird 
in a coat of arms is drawn flying, or having 
its wings spread out. 
VOLCANIC formations. The products 
of volcanoes are ejected stones and ashes ; 
lava and water mixed with ashes, of a slimy 
consistence : the first order comprehends 
the ejected stones and ashes ; the second, 
the difl’erent kinds of lava ; and the third, 
the matter of muddy eruptions. The stony 
ejections are those which are always thrown 
from the summit of the volcano : they ac- 
cumulate and form the crater, whieh is 
a funnel -shaped hollow. Mineralogists have 
enumerated among ejected stones : 1. Gra- 
nular lime-stone, which is said to contain 
tremolite, pistacite, olivine, angite, Vesu- 
vian, melanite, sommite, and hornblende ; 
2. Granite j 5. Mica-slate ; 4. Green-stone j 
and, 5. Sand-stone. Lava consists of two 
sub-species; viz. slag-lava and foam-lava; 
these do not extend far, having in general 
flowed, in streanis of con-siderable height, 
into hollows, and gradually consolidated 
during its course. Matter of muddy erup- 
tions comprehends volcanic- tuff, which is 
composed sometimes of ashes, sometimes 
of vesicular lava, and probably some particu- 
lar chemical formations. See Volcanoes. 
VOLCANOES, mountains which emit 
ignited matter and smoke through aper- 
tures communicating with cavities in the 
depths of the earth, where eternal tires are 
situated that burn with more or less force 
they are influenced by causes which it 
is impossible should ever be explained by 
actual observation, but that may be con- 
jectured with tolerable success from expe- 
riments. Such have been made by many 
naturalists (who deserve every praise for 
their assiduity and research),' though not 
with an accuracy, that distinguishes those 
of the celebrated Abbe Lazarro Spallan- 
zani, professor of natural liistory in the 
university of Pavia : this gentleman, though 
far advanced in life, acted with a vigour 
and hardihood seldom found even in youth 
and braved danger and death, in a thousand 
' horrid forms, in pursuit of his favourite ob- 
ject, the elucidation of the phenomena of 
volcanic fires. To whom, then, can we with 
more propriety have recourse, in our at- 
causes <md effects ? 
Xhe Abbe observed, in the course of his 
various examinations of craters, that vol- 
canoes emit vast quantities of gas ; and he 
VOL 
found that stony substances were invaria- 
bly, when completely heated by the sub- 
terraneous fire, rarified, inflated, and ren- 
dered cellular, by their elasticity; which 
effect is observable in numbers of lavas 
glasses, and enamels, ejected during eriip! 
tions: and he discovered, in addition, that 
their violence continually raised the liqui- 
fied matter from the interior of the craters 
to their very borders, over which it flowed 
at each impulse. 
He was at the same time equally atten- 
tive to the nature and force of the fire 
w'hich acts in the bowels of volcanic moun- 
tains ; and, in the course of his researches, 
discovered that Vesuvius, /Etna, the Eolian 
Islands, and I*hia, are immense mountains 
composed of rocks that have been liquified’ 
and even vitrified, by the violence of the 
subterraneous conflagration. “ What fire ” 
he exclaim^ « can me produce equivalent 
to these eftects!” Humble, however, as 
all experiments appear with our limited 
means, this venerable philosopher justly 
thought imperfect knowledge of volcanoes 
preferable to contented ignorance, and, 
undismayed by tlie magnitude of the object 
proceeded to ascertain, as far as possible! 
what man is permitted to know on this 
terrific subject. « I have,” he observes, 
discovered, that the fire, of the glass-fur- 
nace will completely refuse the vitrifica- 
ti^s, enamels, pumices, scori®, and lavas, 
of these and other volcanic countries. The 
same will, m like manner, vitrify rocks 
congenerous to those from which these 
mountains have originated, by the means 
of subterranean conflagrations. A less in- 
tense ^e, on the contrary, produces no 
^ch effect on any of these substances. 
Hetei mined to exercise the most rigorous 
research, and to ascertain, with the greatest 
possible- precision, the exact degree of heat 
requisite to produce the above effects, he 
had recourse to the pyrometer of Wedg- 
wood, which he compliments and praises 
by saying, nothing could be better adapted 
lor hi3 purpose. 
The terrific appearance of a volcano in 
eruption is so appalling, so grand, and alto- 
gether so wonderful, that it is by no means 
astonishing the world should suppose the 
vast volumes of smoke, ignited matter, and 
stones, hurled into the air with inconceiva- 
ble violence and rapidity, exclusive of the 
torrents of liquified substances which roll 
down its sides in solemn and destructive 
majesty, were caused by more powerful 
fires than those man has been permitted to 
