[S3] 
mofeta * or damp, which much refembles that of the 
grotto, excepting that it is not permanent : but while 
it lafts, people obferve, that, after having filled the 
place of its fource, it overflows, runs into lower 
grounds, and flops in places, that have any cavities ; 
as water does, when a bafon is too full -j~. 
After the experiment of the flambeau, that of the 
dog was performed before me. The keeper of the 
grotto took the two fore legs of the creature in one 
hand, and the hind legs in the other. He went into 
the grotto, in the middle of which he laid him upon 
his fide, and held him down : immediately the dog 
ftruggled to get loofe, or at leaft to raife his head out 
of the vapour : he panted, as if his breath failed him ; 
rattled in the throat and fnorted, as if to throw out 
fomething, that he did not care to fwallow. After being 
thus tortured for three minutes, his ftrength failed him, 
and he lay quite motionlefs. He was immediately 
carried into the open air, of which he drew in long 
draughts, as a perfon recovering from a fainting fit. 
In the fpace of two minutes he was able to get upon 
his legs', and feemed to be in his natural ftate. This 
dog was young, vigorous, of a middle fize ; and his 
mafter allured me, that he had ufed him for the like 
experiments almofl: every day for above fix months 
pafl:. 
I took a cock, and having carried him into the 
grotto, I plunged his head into the vapour. Scarce- 
ly was it in, when he ftrained to vomit. And 
indeed, the food, which he had taken fome minutes 
before. 
* Mephitis , a deadly or very dangerous exhalation, 
t Neapol. fcient. acad. d< Vefuvii conflagration t comment arias? 
tap. 6 , 
