air which has been lately made noxious. I have 
even fpent feveral hours- in pouring this air from one 
giafs velfel into another, in water, fometimes as cold, 
and fometimes as warm, as my hands could bear it, 
and have fometimes alfo wiped the veflels many 
times, during the courfe of the experiment, in order 
to take off that part of the noxious matter, which 
might adhere to the giafs veffels, and which evi- 
dently gave them an offenfive fmell ; but all thefe 
methods were generally without any fenfible effedl. 
The motion, alfo, which the air received in thefe 
■circumflances, it is very evident, was of no ufe for this 
purpofe. 
This kind of air is not reflored by being expofed to 
die light, or by any other influence to which it is 
expofed, when confined in a thin phial, in the open 
air, for fome months. 
Among other experiments, I tried a great variety 
of different effluvia, which are continually exhaling 
into the air, efpecially of thofe fubflances which are 
known to refill putrefa&ion ; but I could not by thefe 
means effedl any melioration of the noxious quality of 
this kind of air. 
Having read, in the Memoirs of the Imperial So- 
ciety, of a plague not afflidting a particular village, 
in which there was a large fulphur work, I imme- 
diately fumigated a quantity of this kind of air; or 
{(which will hereafter appear to be the very fame 
thing) air tainted with putrefadtion, with the fumes 
of burning brimflone, but without any effedt. 
I once imagined, that the nitrous acid in the air 
might be the general reflorative which I was in 
quell of; and the conjedture was favoured, by find- 
ing 
