jo Dr . Aus^in^s Experiments on 
parts we affign are put together, and the fame compound is 
produced from them. The frequent produdlion of fixed air, 
from fubftances generally not iuppofed to contain the heavy 
inflammable air, has lately given rife to a new fyftem in che- 
miftry. The author of this h fern has the merit of pointing 
out the appearance of fixed air in a 1 mo ft all phlogiftic procefies, 
in the combuftion of various fubftances, in the reduction or 
metals, and in the decompofition of acids ; phenomena which 
cannot otherwife be accounted for, than by (hewing that the 
fpecific matter of charcoal is a compound body; that its com- 
ponent parts are prefect in all thefe precedes ; and in fome of 
them nothing elfe, if we except dephlogifticated air. 
1 have already taken notice of the formation of fixed air 
from nitrous ammoniac, which is now well known to contain 
nothing, but the phlogifticated, light inflammable, and dephlo- 
crifticated airs. This fait, heated in clofe veflels, vieids de- 
£> j 
phlogifticated nitrous air in great abundance, mixed with a 
fmall proportion of fixed air. I have often repeated this expe- 
riment with nitrous ammoniac, which indicated no trace of 
fixed air either with lime water, or with acids, before its de- 
compofition ; but, when the fait was decompofed by heat* I 
always found lime water rendered turbid by the generated air; 
and, upon adding an acid to the turbid lime water, have ob- 
ferved air bubbles to be produced in it. 
When the three elementary airs are in a condenfed ftate, and 
are fet free from any combinations, they unite and form fixed 
air without the aftiftance of heat. Thus fixed air is generally 
produced when metals are diflblved in the nitrous acid. In 
thefe folutions, the component parts of nitrous acid and the light 
inflammable air, being extricated at the fame time, unite before 
they have acquired the aeriform ftate ? and conftitute fixed air. 
Objeds 
