1807.]: 
producing by various mixtures some of 
the grandest operations of nature. It is 
not a qmescent and torpid, but a busy 
and bustling scene. 
Secondiy, Thatit is not a solid or con- 
tinuous mass of matter, as is also com- 
monly jmagined. By solidity, here is 
not understood -that solidity which be- 
longs to the elementary and original par- 
ticles of matter, which are supposed to 
be unchangeable and incapable of actual 
or physical: divisibility Gf indeed there 
be any such,) but such a firm cohesion of 
parts as is not easily overcome or de- 
stroyed. When itis maintained that the 
nucleus of the earth is not one solid 
inass, solid is taken mm the sense in which 
it stands opposed to fluid- Wherever 
there is heat there 1s expansion in every 
direction; and when violent, fluidity. 
But, that the internal heat of the globe 
is strong or violent, is deducible from 
volcanoes, its eflects. The stupendous 
and terrible scenes of globes of flame, and 
fiery stones, forced toa prodigious height, 
mountains melted, and rivers of burning 
Java, attest the violence of that intestine 
agitation from which they flow. 
Thirdly, The existence, the mighty 
power and violence, of internal fires in 
the earth, being established, it follows 
that they must be fed by an aliment 
adapted to such powerful and violent 
effects; and we know not of any other 
kind of aliment equal to such effects, 
besides oxygenous and other gases, 1 a 
state of liquidity or fusion. i 
Fourthly, The most common materials 
from which such gases are extricated, 
appear to be the oily substance, called 
petroleum or rock-oil and sulphur;ofwhich 
last substance inexhaustible quantities are 
found in all voleanic countries, Petro- 
leum is very often found in the cavities 
of limestone; sulphur is found sometimes 
pure, but more generally in combination 
with metals; in which state it is called 
pyrites or fire-stone ; which is commonly 
detined to be sulphur saturated with me- 
tals. Almost ail metals dug from the 
earth are ‘combined with sulphur, In 
the pale-yellow pyrites, which contain 
chiefly sulphur and iron, so violent a fer- 
mentation is excited amongst the consti- 
tuent parts of these minerals, when the 
guantity of them is considerable, that not 
only a sulphareous vapour and heat may 
be perceived, but that the whole kindles 
and burns intensely, The same pheno- 
mena are observabie, and the same re- 
sults are obtained by mixing well toge- 
ther, and moistening a large quantity of 
4 
The Enquirer.—No. XXIV. aaa 
fuings of iron and powdered sulphur, 
This experiment exhibits, in miniature, 
the work that is going on in the great 
laboratory in the bowels of the earth. 
But Spallanzani is of opinion, that in 
the more terrible eruptions of volcanoes, 
another agent is brought into play more 
energetic than the most powerful gases, 
even the gassification of glass. This is 
water, principally thatof the sea, reduced 
to vapour. The subtilty or penetrating 
power of water seems to be more wou- 
derful than that of air itself. It will 
pass through bodies impervious to the 
rays of light. Tt can subtilize itself in 
such a manner as to penetrate other bo- 
dies equally solid and compact, in which 
our eyes, though assisted by a lens of a 
strong magnifying power, cannot discover 
the smallest fissure, or minutest pore, 
The power of water to feed the flame, 
and increase the fierceness of fire, is 
known even to common blacksmiths ; 
who, when they have occasion to raise 
the heat of their furnaces to the greatest 
intensity, besprinkle their fires copiously 
with water, so that to petroleum and 
sulphur we are to add water. It must 
be admitted, that all the knowledge we 
can obtain concerning the aliment of 
subterraneous fire is extremely imperfect, 
It is reasonable, however, from what we 
do know, to infer that it consists im the 
substances above-mentioned, though we 
do not know the manner in which they 
are brought into a state of ignition. 
Tt is certain that the aliment of central 
fireis, when it burns, in very different cir- 
cumstances trom those of our furnaces, 
which cannot burn without the presence 
of atmospheric air, of which the sub- 
terraneous abysses, where volcanic con- 
flagrations begin, are destitute. The 
islands that have been produced by the 
action of submarine volcanoes are almost 
innumerable; and new ones have been 
thrown up even in our times. We can- 
not reasonably suppose the existence of 
atmosphenie air at so prodigious, a depth 
below the sea, where the stbstances 
productive and elementary of volcanoes 
take fire. Here, however, we may be 
permitted to have recourse tothe extrica- 
tion and  deyelopement of oxygen 
gas. It is known that nitre, mixed with 
sulphur, burns rapidly, even in close 
vessels, Nitre, when heat is applied to 
it, yields a great quantity of oxygen 
gas; and sulphur has a strong attraction 
Jor oxygen. As oxygen is thus supplied, 
which is the only principle necessary to 
Cembustion, communication with the at- 
mosphere 
