78 Defcription of the Lake-Palius. ° 
with foam. It would, no doubt, be important to examine 
accurately the nature of this vapour; but though I was pro- 
vided with the proper apparatus, I could not obtain my ob- 
ject, becaufe I durft not venture to wade into the water in 
order to reach the places where the bubbling appeared, and 
which were at a confiderable diftance from the ban 
The mud at the bottom and on the bank, which has a 
black colour, is tenacious, and fmells like pitch. A little 
petroleum has alfo been fometimes found at the furface of 
the water. The whole foil of the fmall plain confifts of 
black, tough, refinous, inflammable earth. A few years ago 
fome ftraw huts in this neighbourhood having been fet on 
fire, the fire was communicated to the ground, which burnt 
with a whitifh dull flame, like that of the inflammable fprings 
in Dauphiny, during feveral months, and was extinguifhed 
with the greateft difficulty, as the fire, when deftroyed in 
one place, broke out in another. Since that period great 
care is taken not to kindle fire in the neighbourhood. @F rom 
this phenomenon I am induced to think, that the air which 
rifes through the water of the lake, and which probably finds 
a paflage through the ground, may be of an inflammable 
nature alfo; as the air of marfhes, which burns without any 
noife. The fertility of this {mall plain is fo great, that it pro- 
duces a moft abundant crop every year, without requiring 
much agricultural care. In walking over the ground a hollow 
noife is heard; which feems a proof of there being beneath 
the furface fubterranean cavities, like thofe of Solfatara near 
Puzzuolo. From thefe circumfiances there is reafon to think 
that this place has been formed from the remains of a fallen 
erater, a part of which is ftill {een in the furrounding moun- 
tains; and between this lake and that of Agnano near Na- 
ples, ioe is no other difference than the greater quantity of 
water in the one, and the more violent Ae of vapour in 
ihe other. Some affert that the vapour of this lake is mor- 
tal; and that no bird, or other animal, can be expofed to it 
without being killed. The vapour alfo which arifes from 
ihe ground is confidered as of a fuilocating nature, fo that 
people who lie down on the earth, or only bend their bodies 
towards it, are expofed to the greatelt danger; though one 
6 may 
