[ 42 ] 
•pa»’tlcularly in caverns, and once on the Solfaterra, 
I he vapour afTc« 5 ts the noilrils, throat, and ftomach, 
jutl as the I'pirit of hartfliorn, or any drong volatile 
lalts, and would i'oon prove fatal if you did not im- 
mediately remove from it. Under the ancient city 
of .Pompeii, the are very frequent and pow^er- 
ful, fo that the excavations that are carrying on there 
are often interrupted by them ; at all times mofetes 
■are to be met with under ancient lavas of Vefuvius, 
^particularly thofe of the great eruption of 1631. In 
-berao’s account of the eruption of 1737, and in the 
•-chapter upon mofete^y he has recorded I'everal curious 
experiments relative to this pha^nomenon. The 
•Canonico Recupero, wdio, as I mentioned to you in 
a former letter, is watching the operations of mount 
'Etna, has juft informed me, that a very powerful 
inofete has lately manifelled itfelf iu the neighbour- 
hood of Etna ; and that lie found near the fpot from 
•whence it .rifes, animals, birds, and infedts, dead, 
and the dronger fort of Ihrubs blafled, whild; the 
grafs and tenderer plants did not feem to be 
afFedled. The circumftance of this mofetey added to 
.that of the frequent earthquakes felt lately at Rhegio 
and Medina, makes it probable that an eruption of 
>mountEtna is at hand. 
I am alarmed at the length of this letter. By en- 
deavouring to make myfelf clearly underflood, I 
have been led to make, what I thought, necedary di- 
gredions. I mud therefore beg of your goodnefs, 
that, fhould you find this memoir in its prefent flate, 
stoo tedious (which I greatly apprehend) to be pre- 
fented 
