160 
fubftance is completely diffolved in this 
acid, no fign of oxygenation appears. 
Indeed, fome very flight fign, barely 
perceivable, fometimes appears on the fo- 
lution of fcale of iron, to which (being 
formed in the open air) it is probable 
that a {mall quantity of oxygen may ad- 
here. But if this {mall quantity be de- 
veloped, I afk why is not more dif- 
covered, when more was prefent? ‘The 
agent is the fame, and it has much more 
matter to act upon. 
They fay that this finery cinder is a 
partial oxyde of iron, and common ru/i of 
iron a complete oxyde. But fince iron 
receives a much greater addition to its 
weight by becoming finery cinder, than 
by being converted into rut, and all the 
-addition is allowed to be pure oxygen, 
the former ought to contain more of this 
principle than thelatter. Befides, finery 
cinder is incapable of becoming ruft. 
The contrary, indeed, is afferted; but let 
the obfervation of the fatt decide between 
us. 
I farther obferve, that when any folid 
fubftance, containing oxygen or dephlo- 
gifticated air, is heated in inflammable 
air, a quantity of fixed air is formed, by 
the union of the oxygen from the fub- 
ftance and the inflammable air in the vef- 
fel. This is the cafe when minium is re- 
vived in thefe circumftances, but not fo 
when finery cinder is ufed, nothing but 
water being found in the vefiel. Alfo, 
when iron, or any fubftance containing 
phlogifton, is heated in dephlogifticated 
air, fixed air is produced. ‘This the an- 
tiphlogiftians fay comes from the plumba- 
go intheiron. But the plumbago in the 
iron employed is not one hundredth part 
of the weight of the fixed air produced, 
af the plumbago could be feparated, and 
decompofed, in the procefs, which it can- 
mot. - 
That fixed air may be produced by the 
union ef dephlogifticated and inflamma- 
ble air, I farther prove by heating toge- 
ther red precipitate, which yields only de- 
phlogifticated air, and flings of iron, 
which give only inflammable air; when 
there is a copious production of the pureft 
fixed airs This, however, I am informed 
my opponents deny. With me the expe- 
riment has never failed. Let others judge 
between us. If this be the faét, here is 
@ copious production of what the anti- 
phlogiftians call the carbonic acid without 
any carbone, which they fay is the only 
fource of it. 
But the argument which my opponents 
urge with the greateft confidenee, is 
. tainly of confiderable 
Interefting Chemical Letter from Dr. Priefiley: 
drawn from the fuppofed ‘compofifion oF 
water, viz. from dephlogifticated and ins 
flammable air burned in a certam propor= 
tion to each other. I fay, however, that 
when thefe two kinds of air are fired to= 
gether, they produce either the nitrous 
acid, or phlogifticated air, whichis known 
to be capable, by decompofition, of form- 
ing nitrous acid. When the mflamma- 
ble air is more than fufficient to form 
nitrous acid, the phlogifticated air ‘is 
produced. This I demonftrate, by firmg > 
the two kinds of air in a clofe tube of 
glafs or copper. 
To this my opponents have objected, 
that when I produce any acid, it mut 
have come from the decompofition of the 
phlogifiicated cir, which I had not beetr 
careful to exclude in the procefs. But I 
am confident that, in my laft method of 
making the experiment, there was not the 
leaft fenfible quantity of phlogifticated air 
prefent, and that, in all the cafes, the 
acid produced was a hundred times more 
than the phlogifticated air could have 
formed. Whenever their fame burned: 
firongly, fo as to enfure more dephlo- 
gifticated air than they wifhed, the water 
they produced was not free from acidity, 
and whenever it was, they found a fur- 
plus of phlogifticated air, which agrees 
with my experiments. 
That dephlogifticated and inflammable 
air, uniting in certain circumftances, can 
form phlogifticated air, I have fhewn in 
feveral procefies. Inilammable air, ex- 
poted to ruft of iron confined by mercury, 
becomes in time wholly phlogifticated 
air, and the ruft is converted into a black 
powder, which no doubt is the fame thing 
with plumbago. ‘This fubftance, ‘there- 
fore, is iron fuperfaturated with phlo- 
gifton. 
On the whole,I amas far as ever from fee-+ 
ing any evidenceof either the compofition 
or,decompefitien of water; but en the con- 
trary, much and very fatisfaétory evidence 
againft it. I write, however, with ne 
other view than to promote a fill and fair 
difcuffion of the fubje&t, which is’ cer- 
importance in 
chemiftry. I am, Sir, your’s, &c. 
Northumberland, J. PRIESTLEY. 
Dec. 20, 1797 . 

To the Editor of the Monthly Magazine. 
« {BERS | 
\ HEN I wrote my note of Jan. 1, 
1798, (which you inferted in 
your number for that month) I had not 
indeed feen Mr. Scctt’s third and fourth 
letters; neither had your i 
if 
