an Eruption of Mount Vefuvius. f ~ 
much more difficult and troublefome than when it was 
only covered with minute afhes. The particularity of 
this laft eruption was, that the lava which ufually ran 
out of the flanks of the volcano, forming cafcades, rivers, 
and rivulets of liquid fire, was now chiefly thrown up 
from its crater in the form of a gigantic fountain of 
fire which falling ftill in fome degree of fufion has, in 
a manner, 
(u) sorrentjno mentions, in his Ifloria del Vefuvio, that the volcano in 
1676 vented itfelf in the like manner. <c Non a torrenti modo mando fuori le 
<s fue vifcere, ma tutti in aria menolla.” Such wonderful, violent, arid fud- 
den emiflions of liquid lava mud have been occafioned by fome accidental and 
extraordinary caufe; and I was inclined to think, that a fudden communication 
of water with the lava in fulion might be the occafion of fuch a phenomenon, 
particularly as we know that pools of rain-water have been found formerly in 
caverns within the bowels of Vefuvius ; and that a river, fuppofed to be that 
Anciently called Draco, and which was buried by an ancient eruption, burft out 
fome years ago with fuch force, from under a Jlratum of lava at Torre del 
Greco, as to be fufficient to turn mills there ; but a late curious experiment, 
mentioned by Monf. de faujas, in his Recherches fur les Volcans eteints, 
p. 176. feems to contradict my fuppofition; and that water introduced to the 
furnace of a volcano, finding there a more rarified air,’ would not produce ari 
explofion. Monf. deslaudes, Dire£tor of the Royal Manufacture of Looking- 
glafs at St. Gobin, made the following experiment in 1768, in the prefence of 
the Duke de la rochefoucault, Monf. de faujas, and others. He poured 
fome water upon a quantity of glafs in fufion, and which had been in that ftate 
in the crucible for twelve hours. The water did not occafion the leafl fermen- 
tation ; but, on the contrary, rolled upon its furface, without even producing 
any fmoke, and after having become feemingly red-hot, like the metal in fufion, 
difappeared in about three minutes, without having occafioned the leafi explo- 
fion. If the great emiflions of lava above mentioned were not then occafioned 
by water mixing with the lava, may not they have been produced by violent 
L 2 fubter- 
