[ 2 44 ] 
may hold the phlogifton too fall, to be deprived of it 
by this acid vapour. 
I fhall conclude my account of thefe experiments - 
with obferving, that the ele&ric fpark is vifible in 
the vapour of ipirit of fait, exaftly as it is in common 
air; and though I kept making this fpark a confi- 
derable time in a quantity of it, I did not perceive 
that any fenfible alteration was made in it. A little 
inflammable air was produced, but not more than 
might have come from the two iron nails which I 
made ufe of in taking the fparks. 
X. 
Miscellaneous Observations. 
Many of the preceding obfervations relating to 
the vinous and putrefactive fermentations, I had 
the curioflty to endeavour to afcertain in what 
manner the air would be affe&ed by the acetous 
fermentation. For this purpofe I inclofed a phial 
full of fmall beer in a jar flanding in water, and 
obferved that during the firfl two or three days 
there was an increale of the air in the jar, but 
from that time it gradually decreafed, till at length 
there appeared to be a diminution of about of 
the whole quantity. During this time the whole 
furface of it was gradually covered with a fcum,~ 
beautifully corrugated. After this there was an 
increafe of the air till there was more than the 
original quantity ; but this muft have been fixed 
air, not incorporated with the reft of the mafs ; for, 
withdrawing the beer, which I found to be four," 
after it had flood i 8 or 20 days under the jar, and 
pafiing 
