on the fpeoific Gravities ,- &c. of -Saline Subfiance a’ 219 
To this it -h as been anfwered, firft, that fixed air in common, 
air is united to forae unknown ball's, which attracts it more 
ftrongly than, quick-lime does; but that it is precipitated from 
that balls by the phlogifton let loofe in phiogiftic procefi.es-, 
which is frill more ftrongly at traded by that balls ; and, fe- 
condly, that the diminution both of the weight and bulk of 
refpirable air in phiogiftic precedes does not arife intirely from 
the .feparation of fixed air, but from fome other caufe. 
But neither of thefe a-nfwers is fatisfadory : for the fuppofi- 
tion of fuch a hafis is evidently gratuitous, being fupported by 
not one experiment. It is alfo contrary to analogy, there 
being no inftance of the feparation of fixed air, nor of any 
other acid, from any fubftance merely by the greater affinity 
of phlogifton to fuch fubftance. It is alfo infufficient for the 
purpole, for which it was framed ; for of dephlogifticated air 
97 parts in 100 are reducible to fixed air by phiogiftic procefies; 
and can it be imagined, that 97 parts in- i.co of it were mere 
fixed air united to lefs than three parts of an unknown balls ? 
I fay, lefs than three -parts ; for, according to the prefent flip- 
pofition, this unknown balls took up the phlogifton of the 
fubftance that feparated the fixed air from it, and yet it, and the 
wffiole quantity of phlogifton it took up, amounted but to three 
parts of an hundred ; can it be fuppofed, that this vaft pro- 
portion of fixed air would not in the leaft affed lime-water, as 
pure dephlogifticated air is known not to do ? Can it be fuppofed, 
that fuch an immenfe quantity of fixed -air, combined with any 
balls, would be fo fuperlatively fitted for all phiogiftic procefies, 
while fixed air, in its difengaged ftate, is totally unfit for 
them ? Befides, this unknown balls, after all, is nothing but 
phlogifticate.d air, with which fixed air is incapable-of contract 
lag any union ; r and if its phlogifton be walked away, it is not 
F f 2 found 
