r r 92 3 
‘Six ounce meafures of air not readily abforbed by 
water, appeared to have been generated from one 
liioufe, which had been putrefying eleven days in con- 
fined air, before it was put into ajar which was quite 
filled with water, for the purpofe of this obfervation. 
Air thus generated from putrid mice {landing in 
water, without any mixture of common air, ex- 
tinguifhes flame, -and is noxious to animals, but 
not more fo than common air only tainted with pu- 
trefadion. It is exceedingly difficult and tedious to 
collect a quantity of this putrid air, not mifcible in 
water, fo very great a proportion of what is collect- 
ed being abforbed by the water, in which it is kept; 
-but what that proportion is, I have not endeavoured 
to afeertain. 
Though a quantity of air be dimmifhed by any 
fubftance putrefying in it, I have not yet found the 
fame effect to be produced by a mixture of putrid air 
with common air; but, in the manner in which I 
have hitherto made the experiment, I was obliged 
to let the putrid air, pais through a body of water ; 
which might inftantly abforb whatever it was in the 
putrid fubftance, that diminifhed the common air. 
Infeds -of various kinds live perfectly well in 
;air tainted with animal or vegetable putrefadion, 
when a Angle infpiration of it would have inftantly 
killed any animal. I have frequently tried the ex- 
periment with flies and butterflies. I have alfo 
obferved, that the aphides will thrive as well upon 
plants growing in this kind of air, as in the open 
air. I have even been frequently obliged to take 
plants out of the putrid air in which they were 
.growing, on purpofe to brufli away -the fwarms of 
5 thefe 
