[ 92 ] 
fo near at hand as I had there, I negle&ed to 
change it, till it turned black, and became of- 
fenfive, but by no means to fuch a degree, as to 
deter me from making ufe of it. In this ftate of 
the water, I obferved bubbles of air to rife from 
it, and efpecially in one place, to which fome 
Ihelves, that I had in it, directed them ; and having 
let an inverted glafs veflel to catch them, in a few 
days I colledted a confiderable quantity of this air, 
which iflued l'pontaneoufly from the putrid water; 
and, putting nitrous air to it, I found that no 
change of colour or diminution enfued, fo that 
it mult have been, in the higheft degree, noxious. 
I repeated the fame experiment feveral times after- 
wards, and always with the fame refult. 
After this, I had the curiofity to try how 
wholefome air would be affected by agitation in 
this water ; when, to my real furprife, I found, that 
after one minute only, a candle would not burn 
in it ; and, after three or four minutes, it was m 
the fame ftate with the air, which had iffued fpon- 
taneoufly from the fame water. 
I alfo found, that common air, confined in a glafs 
veflel, in contact only with this water, and with- 
out any agitation, would not admit a candle to 
burn in it after two days. 
Thefe fads certainly demonftrate, that air which 
either arifes from ftagnant and putrid water, or 
which has been for fome time in conta£t with it,, 
muft be very unfit for refpiration ; and yet Dr. 
Alexander’s opinion is rendered fo plaufible by 
his experiments, that it is very poflible that many 
perfons may be rendered fecure, and thoughtlefs 
