I 
308 Dr* Priestley’s Experiments and X)bfervat ions 
tamed the very fame proportion of phlogifton with iron. Since 
when iron that has been faturated with dephlogiflicated air is 
heated in inflammable air (in which procefs an equal weight of 
water is produced, and the lofs of weight in the iron is equal to 
that of fuch a quantity of dephlogiflicated air as would have 
been one-half of the bulk of the inflammable air which difap- 
pears in that procefs) it might have been concluded, that one- 
fifth of any quantity in water had been inflammable air. 
For, neglecting the difference between the weight of dephlo- 
gifticated and common air, which is not confiderable, and efti- 
mating the latter .p^-th part of water, and inflammable air at 
one-tenth of the weight of common air, an ounce meafure of 
dephlogiflicated air will weigh .6 grain, and two ounce mea- 
fures of inflammable air will weigh .12 grain, which num- 
bers are to each other as 5 to 1 
Though, in confequence of the fmall quantity of fixed air 
which is found in the procefs of melting iron in dephlogifli- 
cated air, this conclufion is not accurate, it is pretty nearly 
fo ; and it is remarkable that, upon this fuppofition, about as 
much inflammable air is expelled from iron when water is com- 
* It appears from the profecution af thefe experiments, that the water which 
is found on heating the fcales of iron in inflammable air, is not formed by the 
dephlogiflicated air expelled from them uniting with the inflammable air in the 
veffel, ;but was the water previoufly contained in the fcales, which is made to quit 
its place by the introduction of the phlogiflon from the inflammable air; yet that 
water carries out with it not much lefs phlogifton than was taken in by the iron, 
and a little more muft be allowed for that water which was neceflary to make 
inflammable air, and which could not enter the iron when it was revived ; fo that, 
on the whole, the phlogifton in the water , that is found after the procefs muft be 
very nearly the fame quantity that is imbibed by the iron, and the water is nearly 
the fame that would have been produced, on the fuppofition of its being made 
from dephlogifticated air expelled from the fcales uniting with the inflammable 
air in the veflel. 
billed 
