extinguish flame, they are equally noxious to animals, they are
equally, and in the same way, offensive to the smell, and they are
restored by the same means.

Since air which has passed through the lungs is the same thing with air
tainted with animal putrefaction, it is probable that one use of the
lungs is to carry off a _putrid effluvium_, without which, perhaps, a
living body might putrefy as soon as a dead one.

When a mouse putrefies in any given quantity of air, the bulk of it is
generally increased for a few days; but in a few days more it begins to
shrink up, and in about eight or ten days, if the weather be pretty
warm, it will be found to be diminished 1/6, or 1/5 of its bulk. If it
do not appear to be diminished after this time, it only requires to be
passed through water, and the diminution will not fail to be sensible. I
have sometimes known almost the whole diminution to take place, upon
once or twice passing through the water. The same is the case with air,
in which animals have breathed as long as they could. Also, air in which
candles have burned out may almost always be farther reduced by this
means.

All these processes, as I observed before, seem to dispose the compound
mass of air to part with some constituent part belonging to it (which
appears to be the _fixed air_ that enters into its constitution) and
this being miscible with water, must be brought into contact with it, in
order to mix with it to the most advantage, especially when its union
with the other constituent principles of the air is but partially
broken.

I have put mice into vessels which had their mouths immersed in
quicksilver, and observed that the air was not much contracted after
they were dead or cold; but upon withdrawing the mice, and admitting
lime water to the air, it immediately became turbid, and was contracted
in its dimensions as usual.

I tried the same thing with air tainted with putrefaction, putting a
dead mouse to a quantity of common air, in a vessel which had its mouth
immersed in quicksilver, and after a week I took the mouse out, drawing
it through the quicksilver, and observed that, for some time, there was
an apparent increase of the air perhaps about 1/20. After this, it stood
two days in the quicksilver, without any sensible alteration; and then
admitting water to it, it began to be absorbed, and continued so, till
the original quantity was diminished about 1/6. If, instead of common
water, I had made