r 
262 
Withing the continuance of the’fuccefs 
you fo well deferve, I am, Sir, 
Yours fincerely, J. ParesTLey. 
Northumberland, Dec. 22, 1798. 

AS I have no other view in this difcuf would be attached to it. 
fion, than to difeover the truth with Te- 
fpect to the queftion which I have brought 
before the Public, T thal] communicate with 
the fame freedom any thing that occurs to 
me in favour of the new fyitem, as well as 
faéts that feem to make againft it. I there- 
fore frankly acknowledge, that I have laid 
too much firefs on the argument from 
finery cinder not dephlogifticating (or on- 
ly in the flighteft degree) marie acid; 
having thought this a proof of its contain- 
ing httle or no oxygen... For this effect is 
not always produced by red precipitate, 
which is known to contain a large quan- 
tity of oxygen, or pure@mir, nor by flowers 
ef zinc, which is always taken for granted 
to contain much of it, 
On the firft pouring of, fpirit of falt on 
the red precipitate frefh made, E have had 
anevident {mell of dephlogifticated marine 
acid, but not afterwards. Alfo the blac 
powder of metcury and lead, which gives 
pure air by heat, does not dephiogifficate 
marine acid, though it makes it give an 
offenfive fmell. But then there is other 
evidence of thefe fubftances .containiirg 
oxygen, not only when expofed'to heat; 
but, with refpeét to the red precipitate, 
when it is even diflolved: in the marine 
acid ; and no evidence of any kind‘ that 
finery cinder contains this principle. For 
this folution of the red precipitate, heated 
with a burning lens im atimoipherical air, 
caufes an addition to its quantity, fromthe 
dephlogifiicated air expelled from. it; 
whereas, when the {elution of finery cinder 
is treated in the fame manner, the con- 
trary effect is produced. ‘The quantity of 
air is diminifhed, and it.is lefs pure than 
before. The fame was alfo the confe- 
quence of heating a folution of iron in 
the fame acid in thefe circunmftances. I 
had the fame refult with a folution of 
finery cinder precipitated. by cauftie vola- 
tile alkali. This was alfo the confequence 
of heating a folution of iren in maririe 
acid, treated in the fame manner. Since, 
therefore, finery cinder, both in this folu- 
tion, and without it, has the fame effeét on 
the atmofpherical air in which it is heated 
that iron has; I conclude that. they beth 
contain the fame principle, viz. phlocifton, 
though the Anery-cinder has much lefs.of 
it than the iron. . 
Another proof ofa calx containing pure 
air, or oxygen, is that, when it, is revived 
in inflammable air, a quantity of fixed air 
- 
2 
Dr. Priefiley on the Deéirine of Phlogifton.” 
- > = 
_ [ May. 
is produced. But this is not the cafe- 
when finery cinder is revived in thefe cir- 
cumftances, though I purpofely prepared 
fome by melting iron in the open air, in 
which cafe I imagined that fome pure air 
In making this 
finery cinder, I obferved that fteel gained 
no ferifible addition of weight in the pro- 
cefs, and iron much lefs than when it is 
made by means of fteam; fomething, no 
doubt, being thrown off from it when it is 
heated in the open air, which cannot ef 
cape when it is farrounded. by fieam in a 
clofe veflel. When it was prepared ina 
clofe glafs veff2] with water init, by means 
of a burning lens, it gained weight ; but 
when it was done over mercury, the ad- 
dition to its weight was little or nothing, 
Since an iron tube is diffolved by heat. 
ing manganele in it, I thought it very 
poilible that the fame dephlogifticated air 
from this fubftance might unite with the 
iron, and that the-finery cinder made in 
this manner might be found to contain 
fome. But when I lately heated iron af- 
fe&ted in this manner in inflammable air, % 
I did no®@ find any fixed air in the. tefi- 
duum ;°fo that it appeared to have got 
nothing but water from the manganefe} 
being the very fame thing with the finery 
cinder which is made by means of fteam. 
Though, therefore, finery cinder not 
dephlogifticating marie acid, 1s no proof 
of its not containing oxygelt, no politive 
evidence has yet been produced that it 
does ; and there is every prefumption that 
it does not. And fo important a thing as 
an entire new fyftem of chemiftry cannot 
be admitted on mere poffibilities. 
Whenever inflammable air is procured by 
means ofa metal, fince water is always pre- 
fent, Antiphlogiftians fay, that it comes 
from a decompofition of this water. But 
fince they fay that water confifts of 85 parts _ 
inweight of oxygento: 5 of hydrogen, there 
ought to be fome evidence of the produc- 
tion of this proportion of oxygen at the 
fame time ; and yet this has not been done 
by any proper evidence, which is the pro- 
duction either of fome acid, of dephlogif- 
,ticated air, or of fome fubftance into which _ 
it is acknowledged to enter. ‘ep 
The only reply of the Antiphlogiftians 
has been, that whenever inflammable air 1s 
procured by means of a metal, that metal 
is reduced ‘to a-calx, and this calx weigh- _ 
: vele 
ing more than the metal, auf contain the 
oxyzen tequired.* And becaufe the ealx 
of mercury’ yields dephlogifticated air, 
and its additional weight is ewing. to it, - 
they prefume that: a// metallic calees de- 
tive their additional weight from the fame 
principle, and. therefore they do not hefi- 
: tate, 
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