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'before, for fome electrical experiments : but either it 
had not changed colour at all, or the difference, if 
any, was not difcernible. 
By thefe experiments, we do not fee pofitively 
what this fluid is, which quenches flame, and kills 
animals in the Grotto de Cani ; but in my opinion 
we learn pretty well what it is not. We may fay 
with great probability, that it is neither fulphureous, 
nor arfenical, nor alcali, nor acid, to the degree of 
being dangerous, or of doing fudden mifchief by any 
of thefe qualities. Befides, it makes no impreflion 
on the fkin of the hand ; which might make one 
believe, that it would make none on the face, eyes, 
tongue, or perhaps on the internal parts of the body, 
if it were convey’d in only by the fame ways with 
the food. But let us not hop at conjectures : here 
are faCts, which anfwer thefe quehions. 
Embolden’d by all the experiments above-recited, 
and by the inferences^ which I drew from them, I 
thought I fhould not commit an imprudent aCtion, 
in plunging myfelf into the vapour, with the pre- 
caution however of not breathing it, and of haying 
but very little time in it. I kneeled down in the 
grotto, and leaning both my hands on the ground, I 
bowed my face forward to within two or three inches 
of the bottom; keeping my eyes open, my tongue a 
little way out of my mouth, and holding my breath 
for a moment. 
In this firh immerflon I felt a touch pretty much 
like that of boiling water containing fome fait; which 
inhantly made me fhut my eyes, by a motion natu- 
ral to that organ, when any thing but quiet pure air 
hrikes it. But it was not attended with any painful 
H impreflion. 
