ai + eS * at bh ir... we 
, oe 
4 5 
1799-] 
To the Editor of the Monthly Magazine. 
SIR, 
OST of the fubftances which have 
been made ufe of to phlogifticate 
air, gain an addition of weight in the pro- 
cefs; in confequence of which, it has been 
taken for granted by the antiphilogiltians, 
that nothing is emitted trom them ; but 
that they only imbibe the dephlogifticated 
air, which is one conftituent part of the at- 
mofphere, leaving the cther part, which 
they call azote, unaltered. It was, there- 
fore, defirable to find fome fubftance which 
would not gain any weight in the procels, 
and yet have the fame effect in phlogifi- 
cating air; for, the dephlogifticated air, 
not uniting with the fubftance expofed to 
it, muft neceflarily form tome other com- 
bination, 
This end was, in fome meafure, an- 
fwered by feel, which contairing, ac- 
cording to the common hypothefis, more 
phlogifton than iron, would, I thought, 
part with more by the application ot heat, 
and receive lefs addition ; and this I found 
to be the cafe. But it was more com- 
pletely anfwered by black bones, which, 
without gaining any thing by the appli- 
cation of heat in any circumftances, be- 
come white in the procefs. If this be 
done in conmmon air, as it cannot imbibe 
the dephlogifticated air, which difappears, 
this air is difpofed of two different ways : 
for, one part of it contributes to torm fixed 
air, and another part forms an union with 
fomething emitted from the bones; and 
makes an addition to the phlogifticated air; 
and accordingly there is more of it found 
after this procefs with the black bones 
than with iron, and many other fubftances 
which receive an addition of weight in 
the procefs. Whence, I afk, cancome this 
addition of phlogiiticated air, but from an 
union of phlogifton emitted from the bones 
and the dephlogifticated air in the atmof- 
pherical air expofed to them ? Confequent- 
ly, phlogifticated air, or axofe, is not a fim- 
ple fubftance,as the antiphlogiltians main- 
tain, but a compound. Alfo, whence can 
come the fixed air procured in the fame pro- 
cefs, but from a different combination of 
the fame principles, and not, as they fay, 
from carbone, which is a fubftance of ve- 
getable origin, and has no place here. 
That the thing which conftitutes the 
blacknefs of the bones is the fame with 
that which has always been called phlo- 
gilton, is evident trom its forming inflam- 
mable air, if there be waiter to fupply it 
with a bafis. For I now find, that if they 
be heated in phlogifticated air, which can- 
not by parting with any thing contribute 
© Mownrury Mac. No. xiv. 
ry ° Dee) ical "ir a ee, ae 
mm 
or": ~- *-/g ‘ 
cr 
Experiments made with Ivory-black and Diamonds. 252 
to: their whitenefs, they neverthelefs be- 
come white, the air is increafed in quan- 
tity, and this increafe is inflammable air. 
For thefe experiments I find zwory-dlack, 
which ts the coal of ivory, ufed by pain- 
ters, more convenient than the bones I 
made ufe of before. To prepare this fub- 
{tance for the experiments, I fill an earthen 
tube with it, and clofing it with clay, 
expofe it a confiderable time, at leafta 
quarter of an hour, to the greateft heat 
of a fmith’s fire, which will expel from it 
every thing that is volatile; fo that no 
heat that I can apply to it afterwards will 
affect it, except by means of fome cther 
fubftance, with which that which cenfti- 
tutes its blacknefs has an afhnity, and 
with which it can combine, _ 
Heating a quantity of ivory-black pre 
pared in this manner, in 6% ounce mea- 
fures, of atmofpherical air, there was no 
fenfible change produced in its quantity ; 
but, on examining it, I found in it one 
ounce meafure ef fixed air, and the re- 
mainder completely phlogifticated, which 
is in the propoition of 84 parts in 1003 
whereas the antiphlogiftians fay, that a 
portion of atmofpherical air contains only 
73 parts of phlogifticated air. It is evi- 
dent, alfo, that both thefe fubftances, viz. 
fixed air and phlogifticated air confift of 
the fame principles, viz. dephlogifiicated 
air and phlogifton. 
The very different proportions in which 
atmofpherical air is diminifhed in differen 
procefles, is a proo: that in fome of them 
there muit be a generation of phlogifticated 
air. Whenair is diminifhed by iron filings 
and fulphur, moiftened with water, the pro- 
portion of phlogifticated air is that which 
Mr. Lavoifier ftates, viz. 73 parts in 100. 
But when I made the mixture without any 
water, I found that 110 meafures were 
in fix days reduced ‘only to 90, completely 
phl gifticated, which ts in the proportion 
of 81.8 in roo. Again, 140 ounce mea- 
fures were, by the fame dry iron filings 
and fulphur, reduced to 113, which isin 
the proportion of 80.6 in 100. But fome 
moitture getting to this mixture the third 
time that it was ufed, 155 ounce mea- 
fures of air were reduced by it to 116, 
which is in the proportion of 74 in 100. 
By the flow burning of phofphorus, 60 
ounce meafures of atmofpherical air were 
reduced to 48, at another time to 483; 
and 50 ounce meafures were reduced to 
40, which is in the proportion of 80.3_ 
of phlogifticated air in 100. But by re- 
peatedly firing the phofphorus with a 
burning lens, 100 ounce meafures were re- 
duced to 89, completely phlogifticated. 
a Ag Waat 
