J 
1799.] 
tate, in thes nomenclature, to denominate 
them all, without exception, oxydes. Thus 
they call finery cinder a black oxyde of tron, 
though they produce no direét evidence of 
its containing any oxygen at all. But it 
by no means follows, that becaufe one 
_ calx ofa metal owes its additional weight 
efent over it in a red heat, though inflam. 
to oxygen, all the reit do fo. 
Indeed the calces of the fame metal are 
in this, and in other refpects, different from 
one another. Finery cinder, for example, 
is a very different thing from the common 
rift of tron, coniilting of different princi- 
ples. From finery cinder nothing can be 
got by mere heat; bue fromruft of iron a 
quantity of fixed air may be extracted. 
From 1277 grains of the common ruft 
of iron, I got 4.5 ounce meafures of air, 
of which ouly about one 30th part was 
not fixed air, the remainder (of the ftand- 
ard of 1, 6) was flightly inflammable, pro- 
bably from the gun barrel in which the 
experiment was made. 
_ The addition that is made to iron by 
rufting in theopen air, I do not find to be 
more than 30 or 40 grains to an ounce; 
whereas the addition made to iron, when 
it is converted into finery cinder, is near 
one half of its original weight. I find, ” 
however, much variety in this refpect. 
When the finery cinder is made by a burn- 
ing lens in the open air, the addition to its 
weight is the leaft, and when it is made in 
clote veflels with fteam, it is the greateft, 
Notwith{tanding this very great difference 
between fiery cinder and the common rife 
girs the Antiphlogiltians {cruple nct to 
ay, but without any examination, that 
finery cinder is an imperfect oxyde of iron, 
and the common ruft a more perfeg one. 
But if finery cinder ever be converted ‘in- 
to ruft, which I have never found to be 
the cafe, it muft, by fome proce{s or other, 
natural or artificial, be firft converted into 
iron, in which cafe it will lofe much of its 
weight. 
The oniy circumftance that gives any 
plaufibility to the finery cinder being an 
oxyde of iron, is the addition that is gained 
to the weight of the iron. © But when zizc 
is treated in the fame manner, fteam being 
mable air is procured, the zinc gains no 
addition of weight; fo that, in this cafe, 
there is no colour for faying that the wa- 
ter is decompofed. The fubftance that 
is produced in thefe circumfances I have 
called fowers of xinc, bécaufe it is a calx 
of zinc; and at that time I prefumed 
that it muft haverall the properties of the 
commion flowers of zinc, which may con- 
fain oxygen. But I have treated this -pe- 
culiaxr calyx of zinc, made without agcei3 
¢ 
Dr. Priefley ou the Doéirine of Phlogifion. 
25 3 
of air, in all the methods that I can think 
of,. without being able to find any fign of 
oxygen init,any mone than in finery cinder. 
When I treated it in-common air, the air 
was not increafed, but diminifhed; the 
fame effect that is preduced by heating 
finery cinder. 
As I could find no oxygen in the pre-. 
cipitate of iron diffolved in acids, I have 
not been able to find any in thofe of zinc. 
The moft unexceptionable that I could 
think of, is that by cauftic volatile alkali. 
This fubftance I heated in atmofpherical 
air both when moift and dry, left expofure 
to the atmofphere fhould make fome difter- 
ence init; but with the fame refult. The 
air in w¥ch. it was treated was rendered 
much worfe than common air, though in 
one cafe the quantity was increafed from 
% to 8 ounce meafures. Half an ounce 
meafure was fixed air, and the reft of the 
ftandard of 1, 8, extinguifhing a candle; 
fo that. it was almoft wholly phlogifticated. 
It therefore feemed to have imbibed part 
of the pure air, and to have given ou 
phlogifticated air. , 
Filings of zinc yield much inflammable 
air in pure water, though I do not find 
that they can by this means be reduced 
to a complete calx, at leaft in a moderate 
time. But the imperfect calx to whieh 
this metal is by this means reduced, does 
“not appear to contain any oxygen. When 
it was heated in common air, the quantity 
of air was not increafed, about one twen- 
ticth part of it was fixed air, and the re- 
mainder of the ftandard of 1, 5. The 
water in which the filings of zinc had been 
immerfed, gave out air much worfe than 
common air, and it was pevfeétly free 
from acidity. Iron filings will yield alfo 
inflammable atr in water, and this water 
gives out air that is worfe than common 
air, as does the water over which tin and 
other metals are calcined. 
That the calces of metals do in-general 
contain oxygen, I have no doubt ;_ becaufe 
the dephlogifticated part of atmofpherical 
air difappears when they, are calcined in it. 
But there is reafon to think that a great 
part of the addition of weight which they 
thereby acquire is mere water, while the 
oxygen will attacn itfelf to other fub- 
ftances in preference to the calx, if they 
be prefent. One evidence of this is, that 
when they are calcined over lime water, 
the lime is precipitated; whereas, if the 
calx had imbibed all the dephlogitticated 
air that difappeared, the lime water would 
not have bren affected by the proceis.; 
this precipitation of the lime coming, no 
doubt, from fixed air, which JT have (uffi- 
ciently proved, confills of dephlogifticated 
air 
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