... - . . c 5° 3 
equilibrium, as if it were a liquor : its furface, mucff 
better terminated than that of other vapours, ba- 
lances vifibly under the air, as if thefe two lubft ances- 
were unwilling to intermix. 
I entered the grotto, and found the ground moifi; 
and I was allured, that that was its ufual flate. This 
moifture is obfervable likewife all around the Tides, 
to the height of ten inches, and no more. Of this 
you may eafily judge by the colour of the earth, 
which in that part is browner and fofter than any- 
where elfe. And yet this moilture never increafes to 
the degree of forming any drainings, or even the 
lead; vifible drops. Nor is there any faline efflo- 
refcence to be perceived, as is Teen on the walls of 
the ftoves above-mentioned. After having flood up- 
right fome minutes, I could remark nothing more 
than a flight earthy fmell, like that which commonly 
prevails in fubterraneous places, which have been kept 
diut. But I felt about my feet a gentle warmth, 
which Teem’d to rife about the Tame height with 
the vapour already mentioned. In order to be cer- 
tain of this, I put down my hand, and had the Tame 
fenfation as if I had thrud: it into the deam of boiling 
water, at eight or ten inches above the evaporating 
velfel. From another immerlion of my hand, which 
laded about a minute, it contracted neither fmell nor 
tafte, that I could perceive by applying it to my 
nofe, or laying my fingers on my tongue. A Tmall 
thermometer, graduated according to M. de Reaumur’s 
Tcale, which I left on the ground in the grotto Tor 
above half an hour, marked 29 degrees above the 
freezing point. It would probably have rifen higher, 
if the door had not been left open. For, when I made 
this 
