2 1) 6 Dr. Pr i est l e y’s Experiments and Obfer vat ions 
lateft difcoveries, fixed air and water appear to confift of the 
fame ingredients, namely dephlogifticated and inflammable air. 
However, in this change of the water we cannot be abfolutely 
lure that the fame proportion of the ingredients is contained, and 
therefore it cannot be abfolutely determined whether the inflam- 
mable air which it contains enters wholly into the fixed air, or 
not. Farther experiments, or a careful comparifon of thefe ex- 
periments with thofe made by Mr. Kirwan and others, may 
perhaps throw fome light upon this fubjedt. Whether the com- 
bined fixed air comes wholly from the charcoal, or whether the 
charcoal only fupplies the phlogifton, and the water its bafis, 
that is, the dephlogifticated air, deferves to be inveftigated. 
Before I conclude my account of the experiments with char* 
coal, I would obferve, that there is another in which I place 
fome dependan.ee, in which, with the lofs of 178 grains of 
charcoal, and 528 grains of water, I procured 1410 ounce 
meafures of air, of which the laft portion (for I did not exa- 
mine the reft) contained one-fixth part of uncombined fixed 
air. This was made in an earthen tube glazed on the outfide. 
The experiments with iron were more fatisfadfory than thofi 2 
with charcoal, being fubjedt to lefs variation ; and it is ftill 
more evident from them, that the inflammable air does not 
come from the water , but only from the iron, as the quantity 
of water expended, added to the weight of the air produced, 
was as nearly as could be expedted in experiments of this kind, 
found in the addition of weight gained by the iron. And 
though the inflammable air procured in this procefs is between 
one-third and one-half more than can be procured from iron by 
a folution in acids, the reafon may be, that mtfch phlogifton 
is retained in the folutions, and therefore much more may be 
expelled from iron, when pure water, without any acid, takes 
the place of it. I would further obferve, that the produce of 
air. 
