228 Continuation of the Experiments and Obfirvat Ion's 
mable air and the dephlogifticated part of common air, which 
after this union is abforbed by the calx. It is true, that the 
mercurial calx, and alio the calces of lead, and many others 1 , 
yield dephlogifticated air; but then the mercury is always 
revived, fo that it is evident, it retakes the phlogifton from the 
fixed air y of which nothing then remains but the dephlogifti* 
cated part, which accordingly appears in the form ot dephlo* 
o-ifticated air. Dr. priestley never found the whole of the 
t> 
mercury revived, and accordingly he recovers a little fixed air 
from the mercurial calx. 2 pr. 217. But Mr. lavoisier 
finds the whole of the mercury revived, and for that reafon 
finds no fixed but all dephlogifticated air ; thus their different 
refults are clearly explained, and probably proceed from the 
different degrees of heat they employed, and the different 
phlogiftication of their acids. The dephlogifticated air that is 
extracted from minium proceeds alfo from a partial revivification 
of the lead, which always takes place*: nor is it wonderful^ 
that this calx fhould dephlogifticate fixed air, fince it dephlo- 
gifticates the marine acid alio, as Mr. scheele has oblerved -f. 
To this it will probably be obje&ed, that dephlogifticated 
air muft pre-exift in the minium, fince it is expelled by the ma- 
rine acid ; but this does not follow ; for if manganefe be dil- 
iblved in the common marine acid which is phlogifticated, and 
afterwards expelled from it by the vitriolic, it will alfo be 
found dephlogifticated. 
I fhall now proceed to inveftigate the proportion of phlo- 
gifton and elementary or refpirable air in fixed air. 
Dr. priestley, in the fourth volume of his Obfervations, 
p. 380. has fatisfactorily proved, that nitrous air parts with as 
* eeaume, 7. i Pott. Lithog. 29. 3 Dift. Cliy. 205, 
f Kon. "Vet. Acad, Handling, vol. XXXV, p. 193. 
much 
