[ l6 S I 
is rather lighter than common air, which favours the 
fuppofition of the fixed, or heavier part of the com- 
mon air, having been precipitated. 
An animal will live nearly, if not quite as long, 
in air in which candles have burned out, as in com- 
mon air. This fa£l furprized me very greatly, having 
imagined that what is called the ccnfumpdon of air 
by flame, or refpiration, to have been of the fame 
nature; but I have fince found, that this fact has 
been obferved by many perfons, and even fo early 
as by Mr. Boyle. I have alfo obferved, that air in 
which brimftone has burned, is not in the leaft in- 
jurious to animals, after the fumes, which at fir ft 
make it very cloudy, have intirely fubflded. 
Having read, in the Memoirs of the Society at 
Turin, Vol. I. p. 41. that air in which candles had 
burned out was perfectly reftored, fo that other 
candles would burn in it again as well as ever, after 
having been expofed to a confiderable degree of 
cold, and likewife after having been com prefled in 
bladders (for the cold had been fuppofed to have 
produced this effedt by nothing but condenfation) : 
I repeated thefe experiments, and did, indeed, find, 
that, when I comprefled the air in bladders, as the 
Count de Saluce, who made the c’bfervation, had 
done, the experiment fucceeded : but having had 
fufficient reafon to diftrufl: bladders, I comprefled 
the air in a glafs veflel ftanding in water; and then 
I found, that this procefs is altogether ineffectual for 
the purpofe. I kept the air comprefled much more, 
and much longer, than he had done, but without 
producing any alteration in it. I alfo find, that a 
greater degree of cold than that which he applied, and 
of 
